diff --git a/.bcr/presubmit.yml b/.bcr/presubmit.yml
index a8ed870656..4e1cdff44d 100644
--- a/.bcr/presubmit.yml
+++ b/.bcr/presubmit.yml
@@ -1,10 +1,15 @@
 matrix:
   platform: ["debian10", "macos", "ubuntu2004", "windows"]
+  bazel: [6.x, 7.x]
 
 tasks:
   verify_targets:
     name: "Verify build targets"
     platform: ${{ platform }}
+    bazel: ${{ bazel }}
+    build_flags:
+    - '--host_cxxopt=-std=c++14'
+    - '--cxxopt=-std=c++14'
     build_targets:
     - '@protobuf//:protobuf'
     - '@protobuf//:protobuf_lite'
@@ -17,9 +22,14 @@ bcr_test_module:
   matrix:
 
     platform: ["debian10", "macos", "ubuntu2004", "windows"]
+    bazel: [6.x, 7.x]
   tasks:
     run_test_module:
       name: "Run test module"
       platform: ${{ platform }}
+      bazel: ${{ bazel }}
+      build_flags:
+      - '--host_cxxopt=-std=c++14'
+      - '--cxxopt=-std=c++14'
       build_targets:
       - "//..."
diff --git a/.github/workflows/staleness_check.yml b/.github/workflows/staleness_check.yml
index 4807ac6d7d..40df4d81e1 100644
--- a/.github/workflows/staleness_check.yml
+++ b/.github/workflows/staleness_check.yml
@@ -18,7 +18,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        branch: [main, 22.x, 23.x, 24.x, 25.x, 26.x]
+        branch: [main, 25.x, 27.x]
         os: [{ name: Linux, value: ubuntu-latest}]
 
     name: Test staleness ${{ matrix.os.name }} ${{ github.head_ref && 'PR' || matrix.branch }}
@@ -26,7 +26,7 @@ jobs:
     if: ${{ github.event.repository.full_name == 'protocolbuffers/protobuf' }}
     steps:
       - name: Checkout ${{ github.head_ref && 'PR' || matrix.branch }}
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout || github.head_ref || matrix.branch }}
 
@@ -49,7 +49,7 @@ jobs:
         # In branches where automatic updates work as post-submits, we don't want to run staleness
         # tests along with user changes.  Any stale files will be automatically fixed in a follow-up
         # commit.
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: staleness
diff --git a/.github/workflows/test_bazel.yml b/.github/workflows/test_bazel.yml
index 2ba549a1e6..3a488a1bb4 100644
--- a/.github/workflows/test_bazel.yml
+++ b/.github/workflows/test_bazel.yml
@@ -1,23 +1,54 @@
-name: Bazel
+name: Bazel Tests
 
-# Controls when the action will run.
 on:
-  # Triggers the workflow on push or pull request events but only for the main branch
-  push:
-    branches: [main]
-  pull_request:
-    branches: [main]
-  # Allows you to run this workflow manually from the Actions tab
-  workflow_dispatch:
+  workflow_call:
+    inputs:
+      safe-checkout:
+        required: true
+        description: "The SHA key for the commit we want to run over"
+        type: string
 
-concurrency:
-    # Cancel previous actions from the same PR or branch except 'main' branch.
-    # See https://docs.github.com/en/actions/using-jobs/using-concurrency and https://docs.github.com/en/actions/learn-github-actions/contexts for more info.
-    group: concurrency-group::${{ github.workflow }}::${{ github.event.pull_request.number > 0 && format('pr-{0}', github.event.pull_request.number) || github.ref_name }}${{ github.ref_name == 'main' && format('::{0}', github.run_id) || ''}}
-    cancel-in-progress: ${{ github.ref_name != 'main' }}
+permissions:
+  contents: read
 
 jobs:
-  test:
-    uses: bazel-contrib/.github/.github/workflows/bazel.yaml@v6
-    with:
-      folders: '["examples"]'
+  examples:
+    strategy:
+      fail-fast: false
+      matrix:
+        runner: [ ubuntu, windows, macos ]
+        bazelversion: [ '7.1.1' ]
+        bzlmod: [true, false ]
+        include:
+          - runner: ubuntu
+            bazelversion: '6.4.0'
+            bzlmod: true
+          - runner: ubuntu
+            bazelversion: '6.4.0'
+            bzlmod: false
+    runs-on: ${{ matrix.runner }}-latest
+    name: Examples ${{ matrix.runner }} ${{ matrix.bazelversion }}${{ matrix.bzlmod && ' (bzlmod)' || '' }}
+    steps:
+      - name: Checkout pending changes
+        uses: protocolbuffers/protobuf-ci/checkout@v3
+        with:
+          ref: ${{ inputs.safe-checkout }}
+
+      - name: Windows startup flags
+        if: runner.os == 'Windows'
+        working-directory: examples
+        shell: bash
+        run: echo "startup --output_user_root=C:/ --windows_enable_symlinks" >> .bazelrc
+
+      - name: Configure Bazel version
+        working-directory: examples
+        shell: bash
+        run: echo "${{ matrix.bazelversion }}" > .bazelversion
+
+      - name: Run tests
+        uses: protocolbuffers/protobuf-ci/bazel@v3
+        with:
+          credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
+          bazel-cache: examples
+          version: ${{ matrix.bazelversion }}
+          bash: cd examples && bazel build //... $BAZEL_FLAGS --enable_bzlmod=${{ matrix.bzlmod }}
diff --git a/.github/workflows/test_cpp.yml b/.github/workflows/test_cpp.yml
index 772402f1c7..8ab24bca85 100644
--- a/.github/workflows/test_cpp.yml
+++ b/.github/workflows/test_cpp.yml
@@ -43,11 +43,11 @@ jobs:
     runs-on: ${{ matrix.config.runner || 'ubuntu-latest' }}
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: ${{ matrix.image }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -63,11 +63,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/gcc:${{ matrix.version }}-6.3.0-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -83,24 +83,24 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
           submodules: recursive
       - name: Cross compile protoc for ${{ matrix.arch }}
         id: cross-compile
-        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v2
+        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           architecture: linux-${{ matrix.arch }}
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-release-${{ matrix.arch }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/emulation:${{ matrix.arch }}-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -135,18 +135,18 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-cmake
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/cmake:3.13.3-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -160,19 +160,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
           submodules: recursive
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-cmake-install
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/cmake:3.13.3-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -193,18 +193,18 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-cmake-examples
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/cmake:3.13.3-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -233,19 +233,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
           submodules: recursive
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-cmake-gcc
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/gcc:12.2-6.3.0-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -264,19 +264,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
           submodules: recursive
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-cmake-submodules
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/cmake:3.13.3-63dd26c0c7a808d92673a3e52e848189d4ab0f17
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -289,19 +289,19 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
           submodules: recursive
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: linux-cmake-32-bit
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/32bit@sha256:8275360dc5d676f3470872d79087901c0e4153453976bea908a92c82e8d209ea
           platform: linux/386
@@ -348,11 +348,11 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel: ${{ matrix.bazel }}
@@ -414,7 +414,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
           submodules: recursive
@@ -438,7 +438,7 @@ jobs:
         shell: bash
 
       - name: Setup sccache
-        uses: protocolbuffers/protobuf-ci/sccache@v2
+        uses: protocolbuffers/protobuf-ci/sccache@v3
         with:
           cache-prefix: ${{ matrix.cache-prefix }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -446,7 +446,7 @@ jobs:
       # Install phase.
       - name: Configure CMake for install
         if: matrix.install-flags
-        uses: protocolbuffers/protobuf-ci/bash@v2
+        uses: protocolbuffers/protobuf-ci/bash@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           command: cmake . ${{ matrix.install-flags }} ${{ env.SCCACHE_CMAKE_FLAGS }} -Dprotobuf_ALLOW_CCACHE=ON
@@ -468,7 +468,7 @@ jobs:
         run: cmake --build . --target clean && rm CMakeCache.txt
 
       - name: Configure CMake
-        uses: protocolbuffers/protobuf-ci/bash@v2
+        uses: protocolbuffers/protobuf-ci/bash@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           command: cmake . ${{ matrix.flags }} ${{ env.SCCACHE_CMAKE_FLAGS }} -Dprotobuf_ALLOW_CCACHE=ON 
diff --git a/.github/workflows/test_csharp.yml b/.github/workflows/test_csharp.yml
index 26d974102a..8b04ff4d91 100644
--- a/.github/workflows/test_csharp.yml
+++ b/.github/workflows/test_csharp.yml
@@ -17,13 +17,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       # TODO Run this with Bazel once codegen is handled properly.
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/csharp:3.1.415-6.0.100-66964dc8b07b6d1fc73a5cc14e59e84c1c534cea
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -36,10 +36,10 @@ jobs:
             dotnet test -c Release -f net6.0 src/Google.Protobuf.Test/Google.Protobuf.Test.csproj"
 
       - name: Clear bazel between docker instances
-        run: sudo rm -rf _build
+        run: sudo rm -rf _build .repository-cache
 
       - name: Run conformance tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/csharp:3.1.415-6.0.100-66964dc8b07b6d1fc73a5cc14e59e84c1c534cea
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -51,7 +51,7 @@ jobs:
     runs-on: windows-2019
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
@@ -70,7 +70,7 @@ jobs:
         shell: bash
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bash@v2
+        uses: protocolbuffers/protobuf-ci/bash@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           command: |
@@ -82,14 +82,14 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Build protobuf C# tests under x86_64 docker image
         # Tests are built "dotnet publish" because we want all the dependencies to the copied to the destination directory
         # (we want to avoid references to ~/.nuget that won't be available in the subsequent docker run)
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: mcr.microsoft.com/dotnet/sdk:6.0.100-bullseye-slim
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -106,7 +106,7 @@ jobs:
         #   running under current user's UID and GID. To be able to do that, we need to provide a home directory for the user
         #   otherwise the UID would be homeless under the docker container and pip install wouldn't work. For simplicity,
         #   we just run map the user's home to a throwaway temporary directory
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: mcr.microsoft.com/dotnet/sdk:6.0.100-bullseye-slim-arm64v8
           skip-staleness-check: true
diff --git a/.github/workflows/test_java.yml b/.github/workflows/test_java.yml
index 0c602f3818..a9abfacaec 100644
--- a/.github/workflows/test_java.yml
+++ b/.github/workflows/test_java.yml
@@ -40,11 +40,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: ${{ matrix.image }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -57,11 +57,11 @@ jobs:
   #   runs-on: ubuntu-latest
   #   steps:
   #     - name: Checkout pending changes
-  #       uses: protocolbuffers/protobuf-ci/checkout@v2
+  #       uses: protocolbuffers/protobuf-ci/checkout@v3
   #       with:
   #         ref: ${{ inputs.safe-checkout }}
   #     - name: Run Linkage Monitor test
-  #       uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+  #       uses: protocolbuffers/protobuf-ci/bazel-docker@v3
   #       with:
   #         image: us-docker.pkg.dev/protobuf-build/containers/test/linux/java:8-1fdbb997433cb22c1e49ef75ad374a8d6bb88702
   #         credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -75,12 +75,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout pending changes
-      uses: protocolbuffers/protobuf-ci/checkout@v2
+      uses: protocolbuffers/protobuf-ci/checkout@v3
       with:
         ref: ${{ inputs.safe-checkout }}
     - name: Build protoc
       id: build-protoc
-      uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v2
+      uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v3
       with:
         image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
         credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -94,7 +94,7 @@ jobs:
         mvn -e -B -Dhttps.protocols=TLSv1.2 install -Dmaven.test.skip=true
       working-directory: java
     - name: Generate pom.xml files from the template
-      uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+      uses: protocolbuffers/protobuf-ci/bazel-docker@v3
       with:
         image: us-docker.pkg.dev/protobuf-build/containers/test/linux/java:11-1fdbb997433cb22c1e49ef75ad374a8d6bb88702
         credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
diff --git a/.github/workflows/test_objectivec.yml b/.github/workflows/test_objectivec.yml
index 185f596fd4..1db6c10c88 100644
--- a/.github/workflows/test_objectivec.yml
+++ b/.github/workflows/test_objectivec.yml
@@ -34,18 +34,18 @@ jobs:
       DEVELOPER_DIR: /Applications/Xcode_14.1.app/Contents/Developer
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Setup ccache
-        uses: protocolbuffers/protobuf-ci/ccache@v2
+        uses: protocolbuffers/protobuf-ci/ccache@v3
         with:
           cache-prefix: objectivec_${{ matrix.platform }}_${{ matrix.xc_config }}
           support-modules: true
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bash@v2
+        uses: protocolbuffers/protobuf-ci/bash@v3
         env:
           CC: ${{ github.workspace }}/ci/clang_wrapper
           CXX: ${{ github.workspace }}/ci/clang_wrapper++
@@ -80,13 +80,13 @@ jobs:
     runs-on: ${{ matrix.OS }}
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Xcode version
         run: sudo xcode-select -switch /Applications/Xcode_${{ matrix.XCODE }}.app
       - name: Pod lib lint
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: cocoapods/${{ matrix.XCODE }}
@@ -125,11 +125,11 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: bazel ${{ matrix.config.bazel_action }}
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel: ${{ matrix.config.bazel_action }} ${{ matrix.config.flags }} ${{ matrix.bazel_targets }}
diff --git a/.github/workflows/test_php.yml b/.github/workflows/test_php.yml
index 6909668759..86d24954b2 100644
--- a/.github/workflows/test_php.yml
+++ b/.github/workflows/test_php.yml
@@ -44,16 +44,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Setup composer
-        uses: protocolbuffers/protobuf-ci/composer-setup@v2
+        uses: protocolbuffers/protobuf-ci/composer-setup@v3
         with:
           cache-prefix: php-${{ matrix.version-short }}
           directory: php
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/php:${{ matrix.version }}-66964dc8b07b6d1fc73a5cc14e59e84c1c534cea
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -82,26 +82,26 @@ jobs:
       image: us-docker.pkg.dev/protobuf-build/containers/test/linux/32bit@sha256:836f2cedcfe351d9a30055076630408e61994fc7d783e8333a99570968990eeb
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Cross compile protoc for i386
         id: cross-compile
-        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v2
+        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           architecture: linux-i386
 
       - name: Setup composer
-        uses: protocolbuffers/protobuf-ci/composer-setup@v2
+        uses: protocolbuffers/protobuf-ci/composer-setup@v3
         with:
           cache-prefix: php-${{ matrix.version }}
           directory: php
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: ${{ env.image }}
           platform: linux/386
@@ -119,26 +119,26 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Cross compile protoc for aarch64
         id: cross-compile
-        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v2
+        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           architecture: linux-aarch64
 
       - name: Setup composer
-        uses: protocolbuffers/protobuf-ci/composer-setup@v2
+        uses: protocolbuffers/protobuf-ci/composer-setup@v3
         with:
           cache-prefix: php-8.1
           directory: php
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/php-aarch64@sha256:77ff9fdec867bbfb290ee0b10d8b7a3e5e434155daa5ec93de7341c7592b858d
           platform: linux/arm64
@@ -161,7 +161,7 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
@@ -180,13 +180,13 @@ jobs:
         run: php --version | grep ${{ matrix.version }} || (echo "Invalid PHP version - $(php --version)" && exit 1)
 
       - name: Setup composer
-        uses: protocolbuffers/protobuf-ci/composer-setup@v2
+        uses: protocolbuffers/protobuf-ci/composer-setup@v3
         with:
           cache-prefix: php-${{ matrix.version }}
           directory: php
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bash@v2
+        uses: protocolbuffers/protobuf-ci/bash@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           command: |
@@ -198,7 +198,7 @@ jobs:
             popd
 
       - name: Run conformance tests
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: php_macos/${{ matrix.version }}
diff --git a/.github/workflows/test_php_ext.yml b/.github/workflows/test_php_ext.yml
index cae0241f72..dfe1951b11 100644
--- a/.github/workflows/test_php_ext.yml
+++ b/.github/workflows/test_php_ext.yml
@@ -17,12 +17,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Package extension
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: php_ext/${{ matrix.version }}
@@ -50,7 +50,7 @@ jobs:
           name: protobuf-php-release
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/php-extension:${{ matrix.version }}-a48f26c08d9a803dd0177dda63563f6ea6f7b2d4
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
diff --git a/.github/workflows/test_python.yml b/.github/workflows/test_python.yml
index a5dbe8f85b..b48da36aab 100644
--- a/.github/workflows/test_python.yml
+++ b/.github/workflows/test_python.yml
@@ -37,11 +37,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: ${{ matrix.image || format('us-docker.pkg.dev/protobuf-build/containers/test/linux/python:{0}-63dd26c0c7a808d92673a3e52e848189d4ab0f17', matrix.version) }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -68,7 +68,7 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
@@ -88,7 +88,7 @@ jobs:
           source venv/bin/activate
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         env:
           KOKORO_PYTHON_VERSION: ${{ matrix.version }}
         with:
diff --git a/.github/workflows/test_ruby.yml b/.github/workflows/test_ruby.yml
index b858bbfcda..38cb5ef5b2 100644
--- a/.github/workflows/test_ruby.yml
+++ b/.github/workflows/test_ruby.yml
@@ -34,11 +34,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: ${{ matrix.image || format('us-docker.pkg.dev/protobuf-build/containers/test/linux/ruby:{0}-6.3.0-a6940b1421a71325ef4c7828ec72d404f56bbf30', matrix.ruby) }}
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -50,20 +50,20 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Cross compile protoc for i386
         id: cross-compile
-        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v2
+        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           architecture: linux-i386
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: i386/ruby:3.0.2-buster
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -81,20 +81,20 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
       - name: Cross compile protoc for aarch64
         id: cross-compile
-        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v2
+        uses: protocolbuffers/protobuf-ci/cross-compile-protoc@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           architecture: linux-aarch64
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/docker@v2
+        uses: protocolbuffers/protobuf-ci/docker@v3
         with:
           image: arm64v8/ruby:3.0.2-buster
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -128,7 +128,7 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
 
@@ -141,7 +141,7 @@ jobs:
         run: ruby --version | grep ${{ matrix.version }} || (echo "Invalid Ruby version - $(ruby --version)" && exit 1)
 
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: ruby_macos/${{ matrix.version }}
@@ -166,11 +166,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/ruby:${{ matrix.ruby }}-6.3.0-a6940b1421a71325ef4c7828ec72d404f56bbf30
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
diff --git a/.github/workflows/test_runner.yml b/.github/workflows/test_runner.yml
index 0d4232bf5c..70cfc27a4a 100644
--- a/.github/workflows/test_runner.yml
+++ b/.github/workflows/test_runner.yml
@@ -52,6 +52,10 @@ on:
 permissions:
   contents: read
 
+concurrency:
+  group: ${{ github.event_name }}-${{ github.workflow }}-${{ github.head_ref || github.ref }}
+  cancel-in-progress: ${{ contains(fromJSON('["pull_request", "pull_request_target", "workflow_dispatch"]'), github.event_name) }}
+
 jobs:
   check-tag:
     name: Check for Safety
@@ -105,6 +109,14 @@ jobs:
   # Note: this pattern of passing the head sha is vulnerable to PWN requests for
   # pull_request_target events. We carefully limit those workflows to require a
   # human stamp before continuing.
+  bazel:
+    name: Bazel
+    needs: [check-tag]
+    uses: ./.github/workflows/test_bazel.yml
+    with:
+      safe-checkout: ${{ needs.check-tag.outputs.checkout-sha }}
+    secrets: inherit
+
   cpp:
     name: C++
     needs: [check-tag]
diff --git a/.github/workflows/test_rust.yml b/.github/workflows/test_rust.yml
index 6018eec953..00c2e4b7bb 100644
--- a/.github/workflows/test_rust.yml
+++ b/.github/workflows/test_rust.yml
@@ -17,13 +17,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
-          image: "us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:7.1.1-75f2a85ece6526cc3d54087018c0f1097d78d42b"
+          image: "us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:7.1.1-97f82260fd504923d8af642d567afb2d83a1959d"
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: rust_linux
           bazel: >-
diff --git a/.github/workflows/test_upb.yml b/.github/workflows/test_upb.yml
index 6f9f25c6a9..e0e0d4d128 100644
--- a/.github/workflows/test_upb.yml
+++ b/.github/workflows/test_upb.yml
@@ -31,11 +31,11 @@ jobs:
 
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/test/linux/sanitize:${{ matrix.config.bazel_version || '6.3.0' }}-75f2a85ece6526cc3d54087018c0f1097d78d42b
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -50,11 +50,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: "us-docker.pkg.dev/protobuf-build/containers/test/linux/gcc:12.2-6.3.0-63dd26c0c7a808d92673a3e52e848189d4ab0f17"
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -68,7 +68,7 @@ jobs:
     runs-on: windows-2022
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # v4.7.0
@@ -76,7 +76,7 @@ jobs:
           cache: pip
           cache-dependency-path: 'python/requirements.txt'
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: "upb-bazel-windows"
@@ -95,7 +95,7 @@ jobs:
     runs-on: macos-12
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - uses: actions/setup-python@61a6322f88396a6271a6ee3565807d608ecaddd1 # v4.7.0
@@ -103,7 +103,7 @@ jobs:
           cache: pip
           cache-dependency-path: 'python/requirements.txt'
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel@v2
+        uses: protocolbuffers/protobuf-ci/bazel@v3
         with:
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
           bazel-cache: "upb-bazel-macos"
@@ -117,11 +117,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Run tests
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/containers/common/linux/bazel:6.3.0-91a0ac83e968068672bc6001a4d474cfd9a50f1d
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
@@ -138,11 +138,11 @@ jobs:
     if: ${{ github.event_name != 'pull_request_target' }}
     steps:
       - name: Checkout pending changes
-        uses: protocolbuffers/protobuf-ci/checkout@v2
+        uses: protocolbuffers/protobuf-ci/checkout@v3
         with:
           ref: ${{ inputs.safe-checkout }}
       - name: Build Wheels
-        uses: protocolbuffers/protobuf-ci/bazel-docker@v2
+        uses: protocolbuffers/protobuf-ci/bazel-docker@v3
         with:
           image: us-docker.pkg.dev/protobuf-build/release-containers/linux/apple@sha256:b3dc9b75d8e599b0e95ed245d89f44b5a4231112f975da89dd02006a484a58df
           credentials: ${{ secrets.GAR_SERVICE_ACCOUNT }}
diff --git a/Cargo.bazel.lock b/Cargo.bazel.lock
index a287466e2e..3855576c78 100644
--- a/Cargo.bazel.lock
+++ b/Cargo.bazel.lock
@@ -1,12 +1,12 @@
 {
-  "checksum": "f93f5d1848bc00c6384273f9fb5273cc1b7fc0cb4dbc2afd776d2feb7b37f3ae",
+  "checksum": "8863e5b8f3da7cf4502f68bea0d455dec4834bf25ff070caaa58a8e1c5ea1a3d",
   "crates": {
     "aho-corasick 1.1.2": {
       "name": "aho-corasick",
       "version": "1.1.2",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/aho-corasick/1.1.2/download",
+          "url": "https://static.crates.io/crates/aho-corasick/1.1.2/download",
           "sha256": "b2969dcb958b36655471fc61f7e416fa76033bdd4bfed0678d8fee1e2d07a1f0"
         }
       },
@@ -53,7 +53,7 @@
       "version": "1.1.0",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/autocfg/1.1.0/download",
+          "url": "https://static.crates.io/crates/autocfg/1.1.0/download",
           "sha256": "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
         }
       },
@@ -101,7 +101,7 @@
         "deps": {
           "common": [
             {
-              "id": "googletest 0.10.0",
+              "id": "googletest 0.11.0",
               "target": "googletest"
             }
           ],
@@ -121,13 +121,16 @@
       },
       "license": null
     },
-    "googletest 0.10.0": {
+    "googletest 0.11.0": {
       "name": "googletest",
-      "version": "0.10.0",
+      "version": "0.11.0",
       "repository": {
-        "Http": {
-          "url": "https://crates.io/api/v1/crates/googletest/0.10.0/download",
-          "sha256": "09213705c85aa0e4b4fff44a3a826a556979a34a266df6bcda703a49c69fb61e"
+        "Git": {
+          "remote": "https://github.com/google/googletest-rust",
+          "commitish": {
+            "Rev": "471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f"
+          },
+          "strip_prefix": "googletest"
         }
       },
       "targets": [
@@ -163,7 +166,7 @@
         "proc_macro_deps": {
           "common": [
             {
-              "id": "googletest_macro 0.10.0",
+              "id": "googletest_macro 0.11.0",
               "target": "googletest_macro"
             },
             {
@@ -173,17 +176,20 @@
           ],
           "selects": {}
         },
-        "version": "0.10.0"
+        "version": "0.11.0"
       },
       "license": "Apache-2.0"
     },
-    "googletest_macro 0.10.0": {
+    "googletest_macro 0.11.0": {
       "name": "googletest_macro",
-      "version": "0.10.0",
+      "version": "0.11.0",
       "repository": {
-        "Http": {
-          "url": "https://crates.io/api/v1/crates/googletest_macro/0.10.0/download",
-          "sha256": "005e4cb962c56efd249bdeeb4ac232b11e1c45a2e49793bba2b2982dcc3f2e9d"
+        "Git": {
+          "remote": "https://github.com/google/googletest-rust",
+          "commitish": {
+            "Rev": "471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f"
+          },
+          "strip_prefix": "googletest_macro"
         }
       },
       "targets": [
@@ -209,14 +215,14 @@
               "target": "quote"
             },
             {
-              "id": "syn 2.0.38",
+              "id": "syn 2.0.43",
               "target": "syn"
             }
           ],
           "selects": {}
         },
         "edition": "2021",
-        "version": "0.10.0"
+        "version": "0.11.0"
       },
       "license": "Apache-2.0"
     },
@@ -225,7 +231,7 @@
       "version": "2.6.4",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/memchr/2.6.4/download",
+          "url": "https://static.crates.io/crates/memchr/2.6.4/download",
           "sha256": "f665ee40bc4a3c5590afb1e9677db74a508659dfd71e126420da8274909a0167"
         }
       },
@@ -263,7 +269,7 @@
       "version": "0.2.17",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/num-traits/0.2.17/download",
+          "url": "https://static.crates.io/crates/num-traits/0.2.17/download",
           "sha256": "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
         }
       },
@@ -332,7 +338,7 @@
       "version": "1.0.14",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/paste/1.0.14/download",
+          "url": "https://static.crates.io/crates/paste/1.0.14/download",
           "sha256": "de3145af08024dea9fa9914f381a17b8fc6034dfb00f3a84013f7ff43f29ed4c"
         }
       },
@@ -385,7 +391,7 @@
       "version": "1.0.69",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/proc-macro2/1.0.69/download",
+          "url": "https://static.crates.io/crates/proc-macro2/1.0.69/download",
           "sha256": "134c189feb4956b20f6f547d2cf727d4c0fe06722b20a0eec87ed445a97f92da"
         }
       },
@@ -448,7 +454,7 @@
       "version": "1.0.33",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/quote/1.0.33/download",
+          "url": "https://static.crates.io/crates/quote/1.0.33/download",
           "sha256": "5267fca4496028628a95160fc423a33e8b2e6af8a5302579e322e4b520293cae"
         }
       },
@@ -494,7 +500,7 @@
       "version": "1.10.0",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/regex/1.10.0/download",
+          "url": "https://static.crates.io/crates/regex/1.10.0/download",
           "sha256": "d119d7c7ca818f8a53c300863d4f87566aac09943aef5b355bb83969dae75d87"
         }
       },
@@ -567,7 +573,7 @@
       "version": "0.4.1",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/regex-automata/0.4.1/download",
+          "url": "https://static.crates.io/crates/regex-automata/0.4.1/download",
           "sha256": "465c6fc0621e4abc4187a2bda0937bfd4f722c2730b29562e19689ea796c9a4b"
         }
       },
@@ -641,7 +647,7 @@
       "version": "0.8.1",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/regex-syntax/0.8.1/download",
+          "url": "https://static.crates.io/crates/regex-syntax/0.8.1/download",
           "sha256": "56d84fdd47036b038fc80dd333d10b6aab10d5d31f4a366e20014def75328d33"
         }
       },
@@ -686,7 +692,7 @@
       "version": "1.0.14",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/rustversion/1.0.14/download",
+          "url": "https://static.crates.io/crates/rustversion/1.0.14/download",
           "sha256": "7ffc183a10b4478d04cbbbfc96d0873219d962dd5accaff2ffbd4ceb7df837f4"
         }
       },
@@ -734,13 +740,13 @@
       },
       "license": "MIT OR Apache-2.0"
     },
-    "syn 2.0.38": {
+    "syn 2.0.43": {
       "name": "syn",
-      "version": "2.0.38",
+      "version": "2.0.43",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/syn/2.0.38/download",
-          "sha256": "e96b79aaa137db8f61e26363a0c9b47d8b4ec75da28b7d1d614c2303e232408b"
+          "url": "https://static.crates.io/crates/syn/2.0.43/download",
+          "sha256": "ee659fb5f3d355364e1f3e5bc10fb82068efbf824a1e9d1c9504244a6469ad53"
         }
       },
       "targets": [
@@ -790,7 +796,7 @@
           "selects": {}
         },
         "edition": "2021",
-        "version": "2.0.38"
+        "version": "2.0.43"
       },
       "license": "MIT OR Apache-2.0"
     },
@@ -799,7 +805,7 @@
       "version": "1.0.12",
       "repository": {
         "Http": {
-          "url": "https://crates.io/api/v1/crates/unicode-ident/1.0.12/download",
+          "url": "https://static.crates.io/crates/unicode-ident/1.0.12/download",
           "sha256": "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"
         }
       },
diff --git a/Cargo.lock b/Cargo.lock
index ea70571b3c..be9bb77bad 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -27,9 +27,8 @@ dependencies = [
 
 [[package]]
 name = "googletest"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "09213705c85aa0e4b4fff44a3a826a556979a34a266df6bcda703a49c69fb61e"
+version = "0.11.0"
+source = "git+https://github.com/google/googletest-rust?rev=471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f#471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f"
 dependencies = [
  "googletest_macro",
  "num-traits",
@@ -39,9 +38,8 @@ dependencies = [
 
 [[package]]
 name = "googletest_macro"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "005e4cb962c56efd249bdeeb4ac232b11e1c45a2e49793bba2b2982dcc3f2e9d"
+version = "0.11.0"
+source = "git+https://github.com/google/googletest-rust?rev=471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f#471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f"
 dependencies = [
  "quote",
  "syn",
@@ -123,9 +121,9 @@ checksum = "7ffc183a10b4478d04cbbbfc96d0873219d962dd5accaff2ffbd4ceb7df837f4"
 
 [[package]]
 name = "syn"
-version = "2.0.38"
+version = "2.0.43"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e96b79aaa137db8f61e26363a0c9b47d8b4ec75da28b7d1d614c2303e232408b"
+checksum = "ee659fb5f3d355364e1f3e5bc10fb82068efbf824a1e9d1c9504244a6469ad53"
 dependencies = [
  "proc-macro2",
  "quote",
diff --git a/MODULE.bazel b/MODULE.bazel
index a389538d3c..b91ab82941 100644
--- a/MODULE.bazel
+++ b/MODULE.bazel
@@ -1,10 +1,9 @@
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/protocolbuffers/protobuf/issues/14313
-PROTOBUF_VERSION = "28.0-dev"
 
 module(
     name = "protobuf",
-    version = PROTOBUF_VERSION,
+    version = "28.0-dev", # Automatically updated on release
     compatibility_level = 1,
     repo_name = "com_google_protobuf",
 )
diff --git a/WORKSPACE b/WORKSPACE
index 63785c3f4b..ef112bb548 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -164,13 +164,6 @@ http_archive(
     patch_cmds = ["find google -type f -name BUILD.bazel -delete"],
 )
 
-load("//python/dist:system_python.bzl", "system_python")
-
-system_python(
-    name = "system_python",
-    minimum_python_version = "3.7",
-)
-
 load("@system_python//:pip.bzl", "pip_parse")
 
 pip_parse(
@@ -222,7 +215,8 @@ crates_repository(
     lockfile = "//:Cargo.bazel.lock",
     packages = {
         "googletest": crate.spec(
-            version = ">0.0.0",
+            git = "https://github.com/google/googletest-rust",
+            rev = "471d4a2a8e8bc74f6d7d9c8eecb4d4e3157b2a9f",
         ),
         "paste": crate.spec(
           version = ">=1",
@@ -232,3 +226,18 @@ crates_repository(
 
 load("@crate_index//:defs.bzl", "crate_repositories")
 crate_repositories()
+
+# For testing runtime against old gencode from a previous major version.
+http_archive(
+    name = "com_google_protobuf_v25.0",
+    strip_prefix = "protobuf-25.0",
+    url = "https://github.com/protocolbuffers/protobuf/releases/download/v25.0/protobuf-25.0.tar.gz",
+)
+
+# Needed as a dependency of @com_google_protobuf_v25.x, which was before
+# utf8_range was merged in.
+http_archive(
+    name = "utf8_range",
+    strip_prefix = "utf8_range-d863bc33e15cba6d873c878dcca9e6fe52b2f8cb",
+    url = "https://github.com/protocolbuffers/utf8_range/archive/d863bc33e15cba6d873c878dcca9e6fe52b2f8cb.zip",
+)
diff --git a/bazel/system_python.bzl b/bazel/system_python.bzl
new file mode 100644
index 0000000000..5126b9bce0
--- /dev/null
+++ b/bazel/system_python.bzl
@@ -0,0 +1,17 @@
+# Copyright (c) 2009-2021, Google LLC
+# All rights reserved.
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Temporary alias to repository rule for using Python 3.x headers from the system."""
+
+load(
+    "//python/dist:system_python.bzl",
+    _system_python = "system_python",
+)
+
+# TODO: Temporary alias. This is deprecated and to be removed in a future
+# release. Users should now get system_python from protobuf_deps.bzl.
+system_python = _system_python
diff --git a/build_defs/BUILD.bazel b/build_defs/BUILD.bazel
index a0e0438d6e..8745e1d618 100644
--- a/build_defs/BUILD.bazel
+++ b/build_defs/BUILD.bazel
@@ -14,10 +14,24 @@ package(
 )
 
 create_compiler_config_setting(
-    name = "config_msvc",
+    name = "config_msvc_cl",
     value = "msvc-cl",
 )
 
+# Caveat: clang-cl support in protobuf is only best-effort / untested for now.
+create_compiler_config_setting(
+    name = "config_clang_cl",
+    value = "clang-cl",
+)
+
+selects.config_setting_group(
+    name = "config_msvc",
+    match_any = [
+        ":config_clang_cl",
+        ":config_msvc_cl",
+    ],
+)
+
 config_setting(
     name = "aarch64",
     values = {"cpu": "linux-aarch_64"},
diff --git a/ci/Windows.bazelrc b/ci/Windows.bazelrc
index 427e923213..dd3bb48b10 100644
--- a/ci/Windows.bazelrc
+++ b/ci/Windows.bazelrc
@@ -1,2 +1,5 @@
 import common.bazelrc
 
+# Workaround for maximum path length issues
+startup --output_user_root=C:/tmp --windows_enable_symlinks
+common --enable_runfiles
\ No newline at end of file
diff --git a/ci/macOS.bazelrc b/ci/macOS.bazelrc
index 465bf0957f..8e7eaf0fb3 100644
--- a/ci/macOS.bazelrc
+++ b/ci/macOS.bazelrc
@@ -2,3 +2,4 @@ import common.bazelrc
 
 build --cxxopt=-std=c++14 --host_cxxopt=-std=c++14
 common --repo_env=BAZEL_NO_APPLE_CPP_TOOLCHAIN=1
+common --xcode_version_config=@com_google_protobuf//.github:host_xcodes
\ No newline at end of file
diff --git a/cmake/protobuf-config-version.cmake.in b/cmake/protobuf-config-version.cmake.in
index 3fa01763ee..269236afdc 100644
--- a/cmake/protobuf-config-version.cmake.in
+++ b/cmake/protobuf-config-version.cmake.in
@@ -44,9 +44,12 @@ macro(_check_and_save_build_option OPTION VALUE)
   endif()
   set(${PACKAGE_FIND_NAME}_${OPTION} ${VALUE} PARENT_SCOPE)
 endmacro()
-_check_and_save_build_option(WITH_ZLIB @protobuf_WITH_ZLIB@)
-_check_and_save_build_option(MSVC_STATIC_RUNTIME @protobuf_MSVC_STATIC_RUNTIME@)
-_check_and_save_build_option(BUILD_SHARED_LIBS @protobuf_BUILD_SHARED_LIBS@)
+
+if(PACKAGE_VERSION_COMPATIBLE)
+    _check_and_save_build_option(WITH_ZLIB @protobuf_WITH_ZLIB@)
+    _check_and_save_build_option(MSVC_STATIC_RUNTIME @protobuf_MSVC_STATIC_RUNTIME@)
+    _check_and_save_build_option(BUILD_SHARED_LIBS @protobuf_BUILD_SHARED_LIBS@)
+endif()
 
 # if the installed or the using project don't have CMAKE_SIZEOF_VOID_P set, ignore it:
 if(CMAKE_SIZEOF_VOID_P AND "@CMAKE_SIZEOF_VOID_P@")
diff --git a/compatibility/BUILD.bazel b/compatibility/BUILD.bazel
new file mode 100644
index 0000000000..e62cb5b133
--- /dev/null
+++ b/compatibility/BUILD.bazel
@@ -0,0 +1,20 @@
+# Simple build tests for compatibility of gencode from previous major versions
+# with the current runtime.
+#
+# To add more test cases in Java, use java_runtime_conformance as below, and add
+# the corresponding http_archive in the WORKSPACE file for the version.
+
+load("//compatibility:runtime_conformance.bzl", "java_runtime_conformance")
+
+# main gencode builds with main runtime as a proof of concept.
+java_runtime_conformance(
+    name = "java_conformance_main",
+    gencode_version = "main",
+)
+
+# Generates a build_test named "conformance_v3.25.0"
+java_runtime_conformance(
+    name = "java_conformance_v3.25.0",
+    gencode_version = "3.25.0",
+    tags = ["manual"],
+)
diff --git a/compatibility/runtime_conformance.bzl b/compatibility/runtime_conformance.bzl
new file mode 100644
index 0000000000..7f1d416412
--- /dev/null
+++ b/compatibility/runtime_conformance.bzl
@@ -0,0 +1,53 @@
+"""Provides a rule to generate a conformance test for a given version of the gencode."""
+
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
+
+def java_runtime_conformance(name, gencode_version, tags = []):
+    """Generates a conformance test for the given version of the runtime.
+
+    For example, runtime_conformance("3.19.4") will generate a build test named "conformance_v3.19.4"
+    that will fail if the runtime at that version fails to compile the unittest proto.
+
+    Args:
+        name: The name of the test.
+        gencode_version: The version of the runtime to test.
+        tags: Any tags to apply to the generated test.
+    """
+
+    if gencode_version == "main":
+        protoc = "//:protoc"
+    else:
+        minor = gencode_version[gencode_version.find(".") + 1:]
+        protoc = Label("@com_google_protobuf_v%s//:protoc" % minor)
+
+    gencode = [
+        "v%s/protobuf_unittest/UnittestProto.java" % gencode_version,
+        "v%s/com/google/protobuf/test/UnittestImport.java" % gencode_version,
+        "v%s/com/google/protobuf/test/UnittestImportPublic.java" % gencode_version,
+    ]
+    native.genrule(
+        name = "unittest_proto_gencode_v" + gencode_version,
+        srcs = [
+            "//src/google/protobuf:unittest_proto_srcs",
+        ],
+        outs = gencode,
+        cmd = "$(location %s) " % protoc +
+              "$(locations //src/google/protobuf:unittest_proto_srcs) " +
+              " -Isrc/ --java_out=$(@D)/v%s" % gencode_version,
+        tools = [protoc],
+    )
+
+    conformance_name = "conformance_v" + gencode_version
+    conformance_lib_name = conformance_name + "_lib"
+    native.java_library(
+        name = conformance_lib_name,
+        srcs = gencode,
+        deps = ["//java/core"],
+        tags = tags,
+    )
+
+    build_test(
+        name = name,
+        targets = [":" + conformance_lib_name],
+        tags = tags,
+    )
diff --git a/conformance/BUILD.bazel b/conformance/BUILD.bazel
index 1cca2e9323..ae9c18c0ed 100644
--- a/conformance/BUILD.bazel
+++ b/conformance/BUILD.bazel
@@ -332,13 +332,14 @@ inline_sh_binary(
     ],
     cmd = """
         php -dextension=$(rootpath //php:extension) \\
-            -d include_path=conformance:src/google/protobuf \\
+            -d include_path=conformance:src/google/protobuf:editions/golden \\
             $(rootpath conformance_php.php)
     """,
     visibility = ["//php:__subpackages__"],
     deps = [
         ":conformance_php_proto",
         "//:test_messages_proto3_php_proto",
+        "//editions:test_messages_proto3_editions_php_proto",
     ],
 )
 
diff --git a/conformance/conformance_dart.dart b/conformance/conformance_dart.dart
index 06b19b6e29..87d4359196 100644
--- a/conformance/conformance_dart.dart
+++ b/conformance/conformance_dart.dart
@@ -65,7 +65,7 @@ ConformanceResponse doTest(ConformanceRequest request) {
   switch (request.requestedOutputFormat) {
     case WireFormat.PROTOBUF:
       try {
-        response.protobufPayload = pb.GeneratedMessage.toBuffer(testMessage);
+        response.protobufPayload = pb.GeneratedMessage.toBinary(testMessage);
       } catch (e) {
         response.serializeError = '$e';
       }
@@ -86,7 +86,7 @@ Future<bool> doTestIo() async {
   }
   final request = ConformanceRequest.fromBuffer(serializedMsg);
   final response = doTest(request);
-  final serializedOutput = pb.GeneratedMessage.toBuffer(response);
+  final serializedOutput = pb.GeneratedMessage.toBinary(response);
   writeLittleEndianIntToStdout(serializedOutput.length);
   stdout.add(serializedOutput);
   await stdout.flush();
diff --git a/conformance/conformance_php.php b/conformance/conformance_php.php
index f250ebf138..a753761147 100644
--- a/conformance/conformance_php.php
+++ b/conformance/conformance_php.php
@@ -1,80 +1,134 @@
 <?php
 
-require_once("Conformance/WireFormat.php");
-require_once("Conformance/ConformanceResponse.php");
-require_once("Conformance/ConformanceRequest.php");
-require_once("Conformance/FailureSet.php");
-require_once("Conformance/JspbEncodingConfig.php");
-require_once("Conformance/TestCategory.php");
-require_once("Protobuf_test_messages/Proto3/ForeignMessage.php");
-require_once("Protobuf_test_messages/Proto3/ForeignEnum.php");
-require_once("Protobuf_test_messages/Proto3/TestAllTypesProto3.php");
-require_once("Protobuf_test_messages/Proto3/TestAllTypesProto3/AliasedEnum.php");
-require_once("Protobuf_test_messages/Proto3/TestAllTypesProto3/NestedMessage.php");
-require_once("Protobuf_test_messages/Proto3/TestAllTypesProto3/NestedEnum.php");
-
-require_once("GPBMetadata/Conformance.php");
-require_once("GPBMetadata/TestMessagesProto3.php");
-
-use  \Conformance\TestCategory;
-use  \Conformance\WireFormat;
-
-if (!ini_get("date.timezone")) {
-  ini_set("date.timezone", "UTC");
+require_once('Conformance/WireFormat.php');
+require_once('Conformance/ConformanceResponse.php');
+require_once('Conformance/ConformanceRequest.php');
+require_once('Conformance/FailureSet.php');
+require_once('Conformance/JspbEncodingConfig.php');
+require_once('Conformance/TestCategory.php');
+require_once('Protobuf_test_messages/Proto3/ForeignMessage.php');
+require_once('Protobuf_test_messages/Proto3/ForeignEnum.php');
+require_once('Protobuf_test_messages/Proto3/TestAllTypesProto3.php');
+require_once('Protobuf_test_messages/Proto3/TestAllTypesProto3/AliasedEnum.php');
+require_once('Protobuf_test_messages/Proto3/TestAllTypesProto3/NestedMessage.php');
+require_once('Protobuf_test_messages/Proto3/TestAllTypesProto3/NestedEnum.php');
+require_once('Protobuf_test_messages/Editions/Proto3/EnumOnlyProto3/PBBool.php');
+require_once('Protobuf_test_messages/Editions/Proto3/EnumOnlyProto3.php');
+require_once('Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3/NestedMessage.php');
+require_once('Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3/NestedEnum.php');
+require_once('Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3/AliasedEnum.php');
+require_once('Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3.php');
+require_once('Protobuf_test_messages/Editions/Proto3/NullHypothesisProto3.php');
+require_once('Protobuf_test_messages/Editions/Proto3/ForeignEnum.php');
+require_once('Protobuf_test_messages/Editions/Proto3/ForeignMessage.php');
+require_once('GPBMetadata/Conformance.php');
+require_once('GPBMetadata/TestMessagesProto3.php');
+require_once('GPBMetadata/TestMessagesProto3Editions.php');
+
+use Conformance\ConformanceRequest;
+use Conformance\ConformanceResponse;
+use Conformance\TestCategory;
+use Conformance\WireFormat;
+use Protobuf_test_messages\Proto3\TestAllTypesProto3;
+use Protobuf_test_messages\Editions\Proto3\TestAllTypesProto3 as TestAllTypesProto3Editions;
+
+if (!ini_get('date.timezone')) {
+    ini_set('date.timezone', 'UTC');
 }
 
 $test_count = 0;
 
 function doTest($request)
 {
-    $test_message = new \Protobuf_test_messages\Proto3\TestAllTypesProto3();
-    $response = new \Conformance\ConformanceResponse();
-    if ($request->getPayload() == "protobuf_payload") {
-      if ($request->getMessageType() == "conformance.FailureSet") {
-        $response->setProtobufPayload("");
-        return $response;
-      } elseif ($request->getMessageType() == "protobuf_test_messages.proto3.TestAllTypesProto3") {
-        try {
-          $test_message->mergeFromString($request->getProtobufPayload());
-        } catch (Exception $e) {
-          $response->setParseError($e->getMessage());
-          return $response;
-        }
-      } elseif ($request->getMessageType() == "protobuf_test_messages.proto2.TestAllTypesProto2") {
-        $response->setSkipped("PHP doesn't support proto2");
-        return $response;
-      } else {
-        trigger_error("Protobuf request doesn't have specific payload type", E_USER_ERROR);
-      }
-    } elseif ($request->getPayload() == "json_payload") {
-      $ignore_json_unknown =
-          ($request->getTestCategory() ==
-              TestCategory::JSON_IGNORE_UNKNOWN_PARSING_TEST);
-      try {
-          $test_message->mergeFromJsonString($request->getJsonPayload(),
-                                             $ignore_json_unknown);
-      } catch (Exception $e) {
-          $response->setParseError($e->getMessage());
-          return $response;
-      }
-	} elseif ($request->getPayload() == "text_payload") {
-		$response->setSkipped("PHP doesn't support text format yet");
-        return $response;
-	} else {
-      trigger_error("Request didn't have payload.", E_USER_ERROR);
+    $response = new ConformanceResponse();
+
+    switch ($request->getPayload()) {
+        case 'protobuf_payload':
+            switch ($request->getMessageType()) {
+                case 'protobuf_test_messages.proto3.TestAllTypesProto3':
+                    $test_message = new TestAllTypesProto3();
+                    break;
+                case 'protobuf_test_messages.editions.proto3.TestAllTypesProto3':
+                    $test_message = new TestAllTypesProto3Editions();
+                    break;
+                case 'conformance.FailureSet':
+                    $response->setProtobufPayload('');
+                    return $response;
+                case 'protobuf_test_messages.proto2.TestAllTypesProto2':
+                case 'protobuf_test_messages.editions.proto2.TestAllTypesProto2':
+                    $response->setSkipped('PHP doesn\'t support proto2');
+                    return $response;
+                case 'protobuf_test_messages.editions.TestAllTypesEdition2023':
+                    $response->setSkipped('PHP doesn\'t support editions-specific features yet');
+                    return $response;
+                case '':
+                    trigger_error(
+                        'Protobuf request doesn\'t have specific payload type',
+                        E_USER_ERROR
+                    );
+                default:
+                    trigger_error(sprintf(
+                        'Protobuf request doesn\'t support %s message type',
+                        $request->getMessageType(),
+                    ), E_USER_ERROR);
+            }
+
+            try {
+                $test_message->mergeFromString($request->getProtobufPayload());
+            } catch (Exception $e) {
+                $response->setParseError($e->getMessage());
+                return $response;
+            }
+            break;
+
+        case 'json_payload':
+            switch ($request->getMessageType()) {
+                case 'protobuf_test_messages.editions.proto3.TestAllTypesProto3':
+                    $test_message = new TestAllTypesProto3Editions();
+                    break;
+                case 'protobuf_test_messages.editions.proto2.TestAllTypesProto2':
+                    $response->setSkipped('PHP doesn\'t support proto2');
+                    return $response;
+                default:
+                    $test_message = new TestAllTypesProto3();
+            }
+
+            $ignore_json_unknown =
+                ($request->getTestCategory() == TestCategory::JSON_IGNORE_UNKNOWN_PARSING_TEST);
+            try {
+                $test_message->mergeFromJsonString(
+                    $request->getJsonPayload(),
+                    $ignore_json_unknown
+                );
+            } catch (Exception $e) {
+                $response->setParseError($e->getMessage());
+                return $response;
+            }
+            break;
+
+        case 'text_payload':
+            $response->setSkipped('PHP doesn\'t support text format yet');
+            return $response;
+        default:
+            trigger_error('Request didn\'t have payload.', E_USER_ERROR);
     }
 
-    if ($request->getRequestedOutputFormat() == WireFormat::UNSPECIFIED) {
-      trigger_error("Unspecified output format.", E_USER_ERROR);
-    } elseif ($request->getRequestedOutputFormat() == WireFormat::PROTOBUF) {
-      $response->setProtobufPayload($test_message->serializeToString());
-    } elseif ($request->getRequestedOutputFormat() == WireFormat::JSON) {
-      try {
-          $response->setJsonPayload($test_message->serializeToJsonString());
-      } catch (Exception $e) {
-          $response->setSerializeError($e->getMessage());
-          return $response;
-      }
+    switch ($request->getRequestedOutputFormat()) {
+        case WireFormat::TEXT_FORMAT:
+            $response->setSkipped('PHP doesn\'t support text format yet');
+            return $response;
+        case WireFormat::UNSPECIFIED:
+            trigger_error('Unspecified output format.', E_USER_ERROR);
+        case WireFormat::PROTOBUF:
+            $response->setProtobufPayload($test_message->serializeToString());
+            break;
+        case WireFormat::JSON:
+            try {
+                $response->setJsonPayload($test_message->serializeToJsonString());
+            } catch (Exception $e) {
+                $response->setSerializeError($e->getMessage());
+                return $response;
+            }
     }
 
     return $response;
@@ -84,25 +138,25 @@ function doTestIO()
 {
     $length_bytes = fread(STDIN, 4);
     if (strlen($length_bytes) == 0) {
-      return false;   # EOF
+        return false;   # EOF
     } elseif (strlen($length_bytes) != 4) {
-      fwrite(STDERR, "I/O error\n");
-      return false;
+        fwrite(STDERR, "I/O error\n");
+        return false;
     }
 
-    $length = unpack("V", $length_bytes)[1];
+    $length = unpack('V', $length_bytes)[1];
     $serialized_request = fread(STDIN, $length);
     if (strlen($serialized_request) != $length) {
-      trigger_error("I/O error", E_USER_ERROR);
+        trigger_error('I/O error', E_USER_ERROR);
     }
 
-    $request = new \Conformance\ConformanceRequest();
+    $request = new ConformanceRequest();
     $request->mergeFromString($serialized_request);
 
     $response = doTest($request);
 
     $serialized_response = $response->serializeToString();
-    fwrite(STDOUT, pack("V", strlen($serialized_response)));
+    fwrite(STDOUT, pack('V', strlen($serialized_response)));
     fwrite(STDOUT, $serialized_response);
 
     $GLOBALS['test_count'] += 1;
@@ -111,10 +165,10 @@ function doTestIO()
 }
 
 while(true){
-  if (!doTestIO()) {
-      fprintf(STDERR,
-             "conformance_php: received EOF from test runner " .
-             "after %d tests, exiting\n", $test_count);
-      exit;
-  }
+    if (!doTestIO()) {
+        fprintf(STDERR,
+            'conformance_php: received EOF from test runner ' .
+            "after %d tests, exiting\n", $test_count);
+        exit;
+    }
 }
diff --git a/conformance/test_protos/test_messages_edition2023.proto b/conformance/test_protos/test_messages_edition2023.proto
index 7688c47321..a6e2bcc863 100644
--- a/conformance/test_protos/test_messages_edition2023.proto
+++ b/conformance/test_protos/test_messages_edition2023.proto
@@ -1,3 +1,10 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2024 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
 edition = "2023";
 
 package protobuf_test_messages.editions;
diff --git a/conformance/text_format_conformance_suite.cc b/conformance/text_format_conformance_suite.cc
index d94f3f2f96..b86566fe33 100644
--- a/conformance/text_format_conformance_suite.cc
+++ b/conformance/text_format_conformance_suite.cc
@@ -9,6 +9,7 @@
 
 #include <cstddef>
 #include <string>
+#include <utility>
 #include <vector>
 
 #include "absl/log/absl_log.h"
@@ -321,6 +322,44 @@ void TextFormatConformanceTestSuiteImpl<MessageType>::RunAllTests() {
                          "optional_int64: -9223372036854775808");
   RunValidTextFormatTest("Uint64FieldMaxValue", REQUIRED,
                          "optional_uint64: 18446744073709551615");
+  // Integer fields - Hex
+  RunValidTextFormatTestWithExpected("Int32FieldMaxValueHex", REQUIRED,
+                                     "optional_int32: 0x7FFFFFFF",
+                                     "optional_int32: 2147483647");
+  RunValidTextFormatTestWithExpected("Int32FieldMinValueHex", REQUIRED,
+                                     "optional_int32: -0x80000000",
+                                     "optional_int32: -2147483648");
+  RunValidTextFormatTestWithExpected("Uint32FieldMaxValueHex", REQUIRED,
+                                     "optional_uint32: 0xFFFFFFFF",
+                                     "optional_uint32: 4294967295");
+  RunValidTextFormatTestWithExpected("Int64FieldMaxValueHex", REQUIRED,
+                                     "optional_int64: 0x7FFFFFFFFFFFFFFF",
+                                     "optional_int64: 9223372036854775807");
+  RunValidTextFormatTestWithExpected("Int64FieldMinValueHex", REQUIRED,
+                                     "optional_int64: -0x8000000000000000",
+                                     "optional_int64: -9223372036854775808");
+  RunValidTextFormatTestWithExpected("Uint64FieldMaxValueHex", REQUIRED,
+                                     "optional_uint64: 0xFFFFFFFFFFFFFFFF",
+                                     "optional_uint64: 18446744073709551615");
+  // Integer fields - Octal
+  RunValidTextFormatTestWithExpected("Int32FieldMaxValueOctal", REQUIRED,
+                                     "optional_int32: 017777777777",
+                                     "optional_int32: 2147483647");
+  RunValidTextFormatTestWithExpected("Int32FieldMinValueOctal", REQUIRED,
+                                     "optional_int32: -020000000000",
+                                     "optional_int32: -2147483648");
+  RunValidTextFormatTestWithExpected("Uint32FieldMaxValueOctal", REQUIRED,
+                                     "optional_uint32: 037777777777",
+                                     "optional_uint32: 4294967295");
+  RunValidTextFormatTestWithExpected("Int64FieldMaxValueOctal", REQUIRED,
+                                     "optional_int64: 0777777777777777777777",
+                                     "optional_int64: 9223372036854775807");
+  RunValidTextFormatTestWithExpected("Int64FieldMinValueOctal", REQUIRED,
+                                     "optional_int64: -01000000000000000000000",
+                                     "optional_int64: -9223372036854775808");
+  RunValidTextFormatTestWithExpected("Uint64FieldMaxValueOctal", REQUIRED,
+                                     "optional_uint64: 01777777777777777777777",
+                                     "optional_uint64: 18446744073709551615");
 
   // Parsers reject out-of-bound integer values.
   ExpectParseFailure("Int32FieldTooLarge", REQUIRED,
@@ -335,30 +374,145 @@ void TextFormatConformanceTestSuiteImpl<MessageType>::RunAllTests() {
                      "optional_int64: -9223372036854775809");
   ExpectParseFailure("Uint64FieldTooLarge", REQUIRED,
                      "optional_uint64: 18446744073709551616");
+  // Parsers reject out-of-bound integer values - Hex
+  ExpectParseFailure("Int32FieldTooLargeHex", REQUIRED,
+                     "optional_int32: 0x80000000");
+  ExpectParseFailure("Int32FieldTooSmallHex", REQUIRED,
+                     "optional_int32: -0x80000001");
+  ExpectParseFailure("Uint32FieldTooLargeHex", REQUIRED,
+                     "optional_uint32: 0x100000000");
+  ExpectParseFailure("Int64FieldTooLargeHex", REQUIRED,
+                     "optional_int64: 0x8000000000000000");
+  ExpectParseFailure("Int64FieldTooSmallHex", REQUIRED,
+                     "optional_int64: -0x8000000000000001");
+  ExpectParseFailure("Uint64FieldTooLargeHex", REQUIRED,
+                     "optional_uint64: 0x10000000000000000");
+  // Parsers reject out-of-bound integer values - Octal
+  ExpectParseFailure("Int32FieldTooLargeOctal", REQUIRED,
+                     "optional_int32: 020000000000");
+  ExpectParseFailure("Int32FieldTooSmallOctal", REQUIRED,
+                     "optional_int32: -020000000001");
+  ExpectParseFailure("Uint32FieldTooLargeOctal", REQUIRED,
+                     "optional_uint32: 040000000000");
+  ExpectParseFailure("Int64FieldTooLargeOctal", REQUIRED,
+                     "optional_int64: 01000000000000000000000");
+  ExpectParseFailure("Int64FieldTooSmallOctal", REQUIRED,
+                     "optional_int64: -01000000000000000000001");
+  ExpectParseFailure("Uint64FieldTooLargeOctal", REQUIRED,
+                     "optional_uint64: 02000000000000000000000");
 
   // Floating point fields
-  RunValidTextFormatTest("FloatField", REQUIRED, "optional_float: 3.192837");
-  RunValidTextFormatTest("FloatFieldWithVeryPreciseNumber", REQUIRED,
-                         "optional_float: 3.123456789123456789");
-  RunValidTextFormatTest("FloatFieldMaxValue", REQUIRED,
-                         "optional_float: 3.4028235e+38");
-  RunValidTextFormatTest("FloatFieldMinValue", REQUIRED,
-                         "optional_float: 1.17549e-38");
-  RunValidTextFormatTest("FloatFieldNaNValue", REQUIRED, "optional_float: NaN");
-  RunValidTextFormatTest("FloatFieldPosInfValue", REQUIRED,
-                         "optional_float: inf");
-  RunValidTextFormatTest("FloatFieldNegInfValue", REQUIRED,
-                         "optional_float: -inf");
-  RunValidTextFormatTest("FloatFieldWithInt32Max", REQUIRED,
-                         "optional_float: 4294967296");
-  RunValidTextFormatTest("FloatFieldLargerThanInt64", REQUIRED,
-                         "optional_float: 9223372036854775808");
-  RunValidTextFormatTest("FloatFieldTooLarge", REQUIRED,
-                         "optional_float: 3.4028235e+39");
-  RunValidTextFormatTest("FloatFieldTooSmall", REQUIRED,
-                         "optional_float: 1.17549e-39");
-  RunValidTextFormatTest("FloatFieldLargerThanUint64", REQUIRED,
-                         "optional_float: 18446744073709551616");
+  for (const auto& suffix : std::vector<std::string>{"", "f", "F"}) {
+    const std::string name_suffix =
+        suffix.empty() ? "" : absl::StrCat("_", suffix);
+
+    RunValidTextFormatTest(absl::StrCat("FloatField", name_suffix), REQUIRED,
+                           absl::StrCat("optional_float: 3.192837", suffix));
+    RunValidTextFormatTestWithExpected(
+        absl::StrCat("FloatFieldZero", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: 0", suffix),
+        "" /* implicit presence, so zero means unset*/);
+    RunValidTextFormatTest(absl::StrCat("FloatFieldNegative", name_suffix),
+                           REQUIRED,
+                           absl::StrCat("optional_float: -3.192837", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldWithVeryPreciseNumber", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: 3.123456789123456789", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldMaxValue", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: 3.4028235e+38", suffix));
+    RunValidTextFormatTest(absl::StrCat("FloatFieldMinValue", name_suffix),
+                           REQUIRED,
+                           absl::StrCat("optional_float: 1.17549e-38", suffix));
+    RunValidTextFormatTest(absl::StrCat("FloatFieldWithInt32Max", name_suffix),
+                           REQUIRED,
+                           absl::StrCat("optional_float: 4294967296", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldLargerThanInt64", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: 9223372036854775808", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldTooLarge", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: 3.4028235e+39", suffix));
+    RunValidTextFormatTest(absl::StrCat("FloatFieldTooSmall", name_suffix),
+                           REQUIRED,
+                           absl::StrCat("optional_float: 1.17549e-39", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldLargerThanUint64", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: 18446744073709551616", suffix));
+    // https://protobuf.dev/reference/protobuf/textformat-spec/#literals says
+    // "-0" is a valid float literal. -0 should be considered not the same as 0
+    // when considering implicit presence, and so should round trip.
+    RunValidTextFormatTest(absl::StrCat("FloatFieldNegativeZero", name_suffix),
+                           REQUIRED,
+                           absl::StrCat("optional_float: -0", suffix));
+    // https://protobuf.dev/reference/protobuf/textformat-spec/#literals says
+    // ".123", "-.123", ".123e2" are a valid float literal.
+    RunValidTextFormatTest(absl::StrCat("FloatFieldNoLeadingZero", name_suffix),
+                           REQUIRED,
+                           absl::StrCat("optional_float: .123", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldNegativeNoLeadingZero", name_suffix), REQUIRED,
+        absl::StrCat("optional_float: -.123", suffix));
+    RunValidTextFormatTest(
+        absl::StrCat("FloatFieldNoLeadingZeroWithExponent", name_suffix),
+        REQUIRED, absl::StrCat("optional_float: .123e2", suffix));
+  }
+  // https://protobuf.dev/reference/protobuf/textformat-spec/#value say case
+  // doesn't matter for special values, test a few
+  for (const auto& value : std::vector<std::string>{"nan", "NaN", "nAn"}) {
+    RunValidTextFormatTest(absl::StrCat("FloatFieldValue_", value), REQUIRED,
+                           absl::StrCat("optional_float: ", value));
+  }
+  for (const auto& value : std::vector<std::string>{
+           "inf", "infinity", "INF", "INFINITY", "iNF", "inFINITY"}) {
+    RunValidTextFormatTest(absl::StrCat("FloatFieldValue_Pos", value), REQUIRED,
+                           absl::StrCat("optional_float: ", value));
+    RunValidTextFormatTest(absl::StrCat("FloatFieldValue_Neg", value), REQUIRED,
+                           absl::StrCat("optional_float: -", value));
+  }
+  // https://protobuf.dev/reference/protobuf/textformat-spec/#numeric and
+  // https://protobuf.dev/reference/protobuf/textformat-spec/#value says
+  // hex or octal float literals are invalid.
+  ExpectParseFailure("FloatFieldNoHex", REQUIRED, "optional_float: 0x1");
+  ExpectParseFailure("FloatFieldNoNegativeHex", REQUIRED,
+                     "optional_float: -0x1");
+  ExpectParseFailure("FloatFieldNoOctal", REQUIRED, "optional_float: 012");
+  ExpectParseFailure("FloatFieldNoNegativeOctal", REQUIRED,
+                     "optional_float: -012");
+  // https://protobuf.dev/reference/protobuf/textformat-spec/#value says
+  // overflows are mapped to infinity/-infinity.
+  RunValidTextFormatTestWithExpected("FloatFieldOverflowInfinity", REQUIRED,
+                                     "optional_float: 1e50",
+                                     "optional_float: inf");
+  RunValidTextFormatTestWithExpected("FloatFieldOverflowNegativeInfinity",
+                                     REQUIRED, "optional_float: -1e50",
+                                     "optional_float: -inf");
+  RunValidTextFormatTestWithExpected("DoubleFieldOverflowInfinity", REQUIRED,
+                                     "optional_double: 1e9999",
+                                     "optional_double: inf");
+  RunValidTextFormatTestWithExpected("DoubleFieldOverflowNegativeInfinity",
+                                     REQUIRED, "optional_double: -1e9999",
+                                     "optional_double: -inf");
+  // Exponent is one more than uint64 max.
+  RunValidTextFormatTestWithExpected(
+      "FloatFieldOverflowInfinityHugeExponent", REQUIRED,
+      "optional_float: 1e18446744073709551616", "optional_float: inf");
+  RunValidTextFormatTestWithExpected(
+      "DoubleFieldOverflowInfinityHugeExponent", REQUIRED,
+      "optional_double: 1e18446744073709551616", "optional_double: inf");
+  RunValidTextFormatTestWithExpected(
+      "DoubleFieldLargeNegativeExponentParsesAsZero", REQUIRED,
+      "optional_double: 1e-18446744073709551616", "");
+  RunValidTextFormatTestWithExpected(
+      "NegDoubleFieldLargeNegativeExponentParsesAsNegZero", REQUIRED,
+      "optional_double: -1e-18446744073709551616", "optional_double: -0");
+
+  RunValidTextFormatTestWithExpected(
+      "FloatFieldLargeNegativeExponentParsesAsZero", REQUIRED,
+      "optional_float: 1e-50", "");
+  RunValidTextFormatTestWithExpected(
+      "NegFloatFieldLargeNegativeExponentParsesAsNegZero", REQUIRED,
+      "optional_float: -1e-50", "optional_float: -0");
 
   // String literals x {Strings, Bytes}
   for (const auto& field_type : std::vector<std::string>{"String", "Bytes"}) {
@@ -438,6 +592,95 @@ void TextFormatConformanceTestSuiteImpl<MessageType>::RunAllTests() {
                          absl::StrCat(field_name, ": '\\xc0'"));
   }
 
+  // Separators
+  for (const auto& test_case : std::vector<std::pair<std::string, std::string>>{
+           {"string", "\"abc\""},
+           {"bytes", "\"abc\""},
+           {"int32", "123"},
+           {"bool", "true"},
+           {"double", "1.23"},
+           {"fixed32", "0x123"},
+       }) {
+    // Optional Field Separators
+    for (const auto& field_type :
+         std::vector<std::string>{"Single", "Repeated"}) {
+      std::string field_name, field_value;
+      if (field_type == "Single") {
+        field_name = absl::StrCat("optional_", test_case.first);
+        field_value = test_case.second;
+      } else {
+        field_name = absl::StrCat("repeated_", test_case.first);
+        field_value = absl::StrCat("[", test_case.second, "]");
+      }
+
+      RunValidTextFormatTest(absl::StrCat("FieldSeparatorCommaTopLevel",
+                                          field_type, "_", test_case.first),
+                             REQUIRED,
+                             absl::StrCat(field_name, ": ", field_value, ","));
+      RunValidTextFormatTest(absl::StrCat("FieldSeparatorSemiTopLevelSingle",
+                                          field_type, "_", test_case.first),
+                             REQUIRED,
+                             absl::StrCat(field_name, ": ", field_value, ";"));
+
+      ExpectParseFailure(
+          absl::StrCat("FieldSeparatorCommaTopLevelDuplicatesFails", field_type,
+                       "_", test_case.first),
+          REQUIRED, absl::StrCat(field_name, ": ", field_value, ",,"));
+      ExpectParseFailure(
+          absl::StrCat("FieldSeparatorSemiTopLevelDuplicateFails", field_type,
+                       "_", test_case.first),
+          REQUIRED, absl::StrCat(field_name, ": ", field_value, ";;"));
+    }
+
+    // Required List Separators
+    RunValidTextFormatTest(
+        absl::StrCat("ListSeparator_", test_case.first), REQUIRED,
+        absl::StrCat("repeated_", test_case.first, ": [", test_case.second, ",",
+                     test_case.second, "]"));
+    ExpectParseFailure(
+        absl::StrCat("ListSeparatorSemiFails_", test_case.first), REQUIRED,
+        absl::StrCat("repeated_", test_case.first, ": [", test_case.second, ";",
+                     test_case.second, "]"));
+    // For string and bytes, if we skip the separator, the parser will treat
+    // the two values as a single value.
+    if (test_case.first == "string" || test_case.first == "bytes") {
+      RunValidTextFormatTest(
+          absl::StrCat("ListSeparatorMissingIsOneValue_", test_case.first),
+          REQUIRED,
+          absl::StrCat("repeated_", test_case.first, ": [", test_case.second,
+                       " ", test_case.second, "]"));
+    } else {
+      ExpectParseFailure(
+          absl::StrCat("ListSeparatorMissingFails_", test_case.first), REQUIRED,
+          absl::StrCat("repeated_", test_case.first, ": [", test_case.second,
+                       " ", test_case.second, "]"));
+    }
+    ExpectParseFailure(
+        absl::StrCat("ListSeparatorDuplicateFails_", test_case.first), REQUIRED,
+        absl::StrCat("repeated_", test_case.first, ": [", test_case.second,
+                     ",,", test_case.second, "]"));
+    ExpectParseFailure(
+        absl::StrCat("ListSeparatorSingleTrailingFails_", test_case.first),
+        REQUIRED,
+        absl::StrCat("repeated_", test_case.first, ": [", test_case.second,
+                     ",]"));
+    ExpectParseFailure(
+        absl::StrCat("ListSeparatorTwoValuesTrailingFails_", test_case.first),
+        REQUIRED,
+        absl::StrCat("repeated_", test_case.first, ": [", test_case.second, ",",
+                     test_case.second, ",]"));
+  }
+  // The test message don't really have all types nested, so just check one
+  // data type for the nested field separator support
+  RunValidTextFormatTest("FieldSeparatorCommaNested", REQUIRED,
+                         "optional_nested_message: { a: 123, }");
+  RunValidTextFormatTest("FieldSeparatorSemiNested", REQUIRED,
+                         "optional_nested_message: { a: 123; }");
+  ExpectParseFailure("FieldSeparatorCommaNestedDuplicates", REQUIRED,
+                     "optional_nested_message: { a: 123,, }");
+  ExpectParseFailure("FieldSeparatorSemiNestedDuplicates", REQUIRED,
+                     "optional_nested_message: { a: 123;; }");
+
   // Unknown Fields
   UnknownToTestAllTypes message;
   // Unable to print unknown Fixed32/Fixed64 fields as if they are known.
diff --git a/conformance/text_format_failure_list_java.txt b/conformance/text_format_failure_list_java.txt
index 8dea2862cd..a035453944 100644
--- a/conformance/text_format_failure_list_java.txt
+++ b/conformance/text_format_failure_list_java.txt
@@ -1,17 +1,20 @@
-Recommended.Proto3.ProtobufInput.GroupUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.MessageUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.RepeatedUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.ScalarUnknownFields_Drop.TextFormatOutput
-Required.Proto3.TextFormatInput.AnyField.ProtobufOutput
-Required.Proto3.TextFormatInput.AnyField.TextFormatOutput
 Recommended.Editions_Proto3.ProtobufInput.GroupUnknownFields_Drop.TextFormatOutput
 Recommended.Editions_Proto3.ProtobufInput.MessageUnknownFields_Drop.TextFormatOutput
 Recommended.Editions_Proto3.ProtobufInput.RepeatedUnknownFields_Drop.TextFormatOutput
 Recommended.Editions_Proto3.ProtobufInput.ScalarUnknownFields_Drop.TextFormatOutput
+Recommended.Proto3.ProtobufInput.GroupUnknownFields_Drop.TextFormatOutput
+Recommended.Proto3.ProtobufInput.MessageUnknownFields_Drop.TextFormatOutput
+Recommended.Proto3.ProtobufInput.RepeatedUnknownFields_Drop.TextFormatOutput
+Recommended.Proto3.ProtobufInput.ScalarUnknownFields_Drop.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.AnyField.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.AnyField.TextFormatOutput
-
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Editions_Proto3.TextFormatInput.StringFieldBadUTF8Hex
+Required.Editions_Proto3.TextFormatInput.StringFieldBadUTF8Octal
+Required.Proto3.TextFormatInput.AnyField.ProtobufOutput
+Required.Proto3.TextFormatInput.AnyField.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Proto3.TextFormatInput.FloatFieldNoOctal
 Required.Proto3.TextFormatInput.StringFieldBadUTF8Hex
 Required.Proto3.TextFormatInput.StringFieldBadUTF8Octal
-Required.Editions_Proto3.TextFormatInput.StringFieldBadUTF8Hex
-Required.Editions_Proto3.TextFormatInput.StringFieldBadUTF8Octal
\ No newline at end of file
diff --git a/conformance/text_format_failure_list_php.txt b/conformance/text_format_failure_list_php.txt
index 404b64a584..e69de29bb2 100644
--- a/conformance/text_format_failure_list_php.txt
+++ b/conformance/text_format_failure_list_php.txt
@@ -1,8 +0,0 @@
-Recommended.Proto3.ProtobufInput.GroupUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.GroupUnknownFields_Print.TextFormatOutput
-Recommended.Proto3.ProtobufInput.MessageUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.MessageUnknownFields_Print.TextFormatOutput
-Recommended.Proto3.ProtobufInput.RepeatedUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.RepeatedUnknownFields_Print.TextFormatOutput
-Recommended.Proto3.ProtobufInput.ScalarUnknownFields_Drop.TextFormatOutput
-Recommended.Proto3.ProtobufInput.ScalarUnknownFields_Print.TextFormatOutput
diff --git a/conformance/text_format_failure_list_python.txt b/conformance/text_format_failure_list_python.txt
index 6754aa4c4b..48abf4e55b 100644
--- a/conformance/text_format_failure_list_python.txt
+++ b/conformance/text_format_failure_list_python.txt
@@ -1,15 +1,99 @@
 # This is the list of text format conformance tests that are known to fail right
 # now.
 # TODO: These should be fixed.
-Required.Proto3.TextFormatInput.FloatFieldMaxValue.ProtobufOutput
-Required.Proto3.TextFormatInput.FloatFieldMaxValue.TextFormatOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatField_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatField_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_f.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_f.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_F.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMinValue_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMinValue_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegative_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegative_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooLarge_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooLarge_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooSmall_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooSmall_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithInt32Max_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithInt32Max_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldZero_F.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatField_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatField_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_f.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_f.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMinValue_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMinValue_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegative_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegative_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Proto3.TextFormatInput.FloatFieldTooLarge_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldTooLarge_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldTooSmall_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldTooSmall_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldWithInt32Max_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldWithInt32Max_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_f.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_f.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.NegDoubleFieldLargeNegativeExponentParsesAsNegZero.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.NegDoubleFieldLargeNegativeExponentParsesAsNegZero.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.NegFloatFieldLargeNegativeExponentParsesAsNegZero.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.NegFloatFieldLargeNegativeExponentParsesAsNegZero.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_f.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_f.TextFormatOutput
+Required.Proto3.TextFormatInput.NegDoubleFieldLargeNegativeExponentParsesAsNegZero.ProtobufOutput
+Required.Proto3.TextFormatInput.NegDoubleFieldLargeNegativeExponentParsesAsNegZero.TextFormatOutput
+Required.Proto3.TextFormatInput.NegFloatFieldLargeNegativeExponentParsesAsNegZero.ProtobufOutput
+Required.Proto3.TextFormatInput.NegFloatFieldLargeNegativeExponentParsesAsNegZero.TextFormatOutput
diff --git a/conformance/text_format_failure_list_python_cpp.txt b/conformance/text_format_failure_list_python_cpp.txt
index 037ca00e13..fc233ed286 100644
--- a/conformance/text_format_failure_list_python_cpp.txt
+++ b/conformance/text_format_failure_list_python_cpp.txt
@@ -1,8 +1,72 @@
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatField_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatField_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMinValue_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMinValue_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegative_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegative_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooLarge_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooLarge_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooSmall_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooSmall_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithInt32Max_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithInt32Max_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_F.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatField_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatField_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMinValue_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMinValue_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegative_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegative_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Proto3.TextFormatInput.FloatFieldTooLarge_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldTooLarge_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldTooSmall_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldTooSmall_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldWithInt32Max_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldWithInt32Max_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
diff --git a/conformance/text_format_failure_list_python_upb.txt b/conformance/text_format_failure_list_python_upb.txt
index 377998b448..85da8a1660 100644
--- a/conformance/text_format_failure_list_python_upb.txt
+++ b/conformance/text_format_failure_list_python_upb.txt
@@ -1,11 +1,75 @@
 # This is the list of text format conformance tests that are known to fail right
 # now.
 # TODO: These should be fixed.
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
-Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatField_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatField_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMaxValue_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMinValue_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldMinValue_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegative_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegative_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNegativeZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooLarge_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooLarge_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooSmall_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldTooSmall_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithInt32Max_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithInt32Max_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.TextFormatOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldZero_F.ProtobufOutput
+Required.Editions_Proto3.TextFormatInput.FloatFieldZero_F.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
 Required.Editions_Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatField_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatField_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanInt64_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldLargerThanUint64_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMaxValue_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldMinValue_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldMinValue_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegative_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegative_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeNoLeadingZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNegativeZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldNoLeadingZeroWithExponent_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldNoNegativeOctal
+Required.Proto3.TextFormatInput.FloatFieldNoOctal
+Required.Proto3.TextFormatInput.FloatFieldTooLarge_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldTooLarge_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldTooSmall_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldTooSmall_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldWithInt32Max_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldWithInt32Max_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldWithVeryPreciseNumber_F.TextFormatOutput
+Required.Proto3.TextFormatInput.FloatFieldZero_F.ProtobufOutput
+Required.Proto3.TextFormatInput.FloatFieldZero_F.TextFormatOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.ProtobufOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesBytes.TextFormatOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.ProtobufOutput
+Required.Proto3.TextFormatInput.StringLiteralBasicEscapesString.TextFormatOutput
diff --git a/csharp/src/Google.Protobuf.Test/JsonFormatterTest.cs b/csharp/src/Google.Protobuf.Test/JsonFormatterTest.cs
index 77da66351e..61adc1da78 100644
--- a/csharp/src/Google.Protobuf.Test/JsonFormatterTest.cs
+++ b/csharp/src/Google.Protobuf.Test/JsonFormatterTest.cs
@@ -900,6 +900,42 @@ namespace Google.Protobuf
             AssertWriteValue(value, "[\n  1,\n  2,\n  3\n]", JsonFormatter.Settings.Default.WithIndentation());
         }
 
+        [Test]
+        public void WriteValueWithIndentation_Any()
+        {
+            var registry = TypeRegistry.FromMessages(ForeignMessage.Descriptor);
+            var formatter = JsonFormatter.Settings.Default.WithIndentation().WithTypeRegistry(registry);
+
+            var nestedMessage = new ForeignMessage { C = 1 };
+            var value = Any.Pack(nestedMessage);
+            const string expectedJson = @"
+{
+  '@type': 'type.googleapis.com/protobuf_unittest3.ForeignMessage',
+  'c': 1
+}";
+
+            AssertWriteValue(value, expectedJson, formatter);
+        }
+
+        [Test]
+        public void WriteValueWithIndentation_NestedAny()
+        {
+            var registry = TypeRegistry.FromMessages(ForeignMessage.Descriptor);
+            var formatter = JsonFormatter.Settings.Default.WithIndentation().WithTypeRegistry(registry);
+
+            var nestedMessage = new ForeignMessage { C = 1 };
+            var value = new TestWellKnownTypes { AnyField = Any.Pack(nestedMessage) };
+            const string expectedJson = @"
+{
+  'anyField': {
+    '@type': 'type.googleapis.com/protobuf_unittest3.ForeignMessage',
+    'c': 1
+  }
+}";
+
+            AssertWriteValue(value, expectedJson, formatter);
+        }
+
         [Test]
         public void WriteValueWithIndentation_CustomIndentation()
         {
diff --git a/csharp/src/Google.Protobuf.Test/Reflection/DescriptorDeclarationTest.cs b/csharp/src/Google.Protobuf.Test/Reflection/DescriptorDeclarationTest.cs
index 65a573ae70..c36acf726a 100644
--- a/csharp/src/Google.Protobuf.Test/Reflection/DescriptorDeclarationTest.cs
+++ b/csharp/src/Google.Protobuf.Test/Reflection/DescriptorDeclarationTest.cs
@@ -137,6 +137,16 @@ namespace Google.Protobuf.Test.Reflection
             Assert.AreEqual(" Zero value comment\n", value.Declaration.LeadingComments);
         }
 
+        [Test]
+        public void OneofComments()
+        {
+            // CommentMessage doesn't have an enum, but we can use TestAllTypes.
+            var message = unitTestProto3Descriptor.FindTypeByName<MessageDescriptor>("TestAllTypes");
+            var oneof = message.Oneofs.Single(o => o.Name == "oneof_field");
+            Assert.NotNull(oneof.Declaration);
+            Assert.AreEqual(" For oneof test\n", oneof.Declaration.LeadingComments);
+        }
+
         private static FileDescriptor LoadProtos()
         {
             var type = typeof(DescriptorDeclarationTest);
diff --git a/csharp/src/Google.Protobuf.Test/Reflection/DescriptorsTest.cs b/csharp/src/Google.Protobuf.Test/Reflection/DescriptorsTest.cs
index 4bd857aacb..f908b2815c 100644
--- a/csharp/src/Google.Protobuf.Test/Reflection/DescriptorsTest.cs
+++ b/csharp/src/Google.Protobuf.Test/Reflection/DescriptorsTest.cs
@@ -204,6 +204,14 @@ namespace Google.Protobuf.Reflection
             TestDescriptorToProto(messageType.ToProto, messageType.Proto);
         }
 
+        [Test]
+        public void MessageDescriptor_IsMapEntry()
+        {
+            var testMapMessage = TestMap.Descriptor;
+            Assert.False(testMapMessage.IsMapEntry);
+            Assert.True(testMapMessage.Fields[1].MessageType.IsMapEntry);
+        }
+
         [Test]
         public void FieldDescriptor_GeneratedCode()
         {
diff --git a/csharp/src/Google.Protobuf.Test/testprotos.pb b/csharp/src/Google.Protobuf.Test/testprotos.pb
index 2116b58c00..255dfb472b 100644
Binary files a/csharp/src/Google.Protobuf.Test/testprotos.pb and b/csharp/src/Google.Protobuf.Test/testprotos.pb differ
diff --git a/csharp/src/Google.Protobuf/JsonFormatter.cs b/csharp/src/Google.Protobuf/JsonFormatter.cs
index 77ca26e7cc..fbcc839707 100644
--- a/csharp/src/Google.Protobuf/JsonFormatter.cs
+++ b/csharp/src/Google.Protobuf/JsonFormatter.cs
@@ -481,6 +481,7 @@ namespace Google.Protobuf {
       }
       IMessage message = descriptor.Parser.ParseFrom(data);
       WriteBracketOpen(writer, ObjectOpenBracket);
+      MaybeWriteValueWhitespace(writer, indentationLevel + 1);
       WriteString(writer, AnyTypeUrlField);
       writer.Write(NameValueSeparator);
       WriteString(writer, typeUrl);
@@ -489,9 +490,9 @@ namespace Google.Protobuf {
         writer.Write(ValueSeparator);
         WriteString(writer, AnyWellKnownTypeValueField);
         writer.Write(NameValueSeparator);
-        WriteWellKnownTypeValue(writer, descriptor, message, indentationLevel);
+        WriteWellKnownTypeValue(writer, descriptor, message, indentationLevel + 1);
       } else {
-        WriteMessageFields(writer, message, true, indentationLevel);
+        WriteMessageFields(writer, message, true, indentationLevel + 1);
       }
       WriteBracketClose(writer, ObjectCloseBracket, true, indentationLevel);
     }
diff --git a/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs b/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs
index f46667ed07..d9bf6b373f 100644
--- a/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/FieldDescriptor.cs
@@ -242,7 +242,7 @@ namespace Google.Protobuf.Reflection
         /// <summary>
         /// Returns <c>true</c> if this field is a map field; <c>false</c> otherwise.
         /// </summary>
-        public bool IsMap => FieldType == FieldType.Message && messageType.Proto.Options != null && messageType.Proto.Options.MapEntry;
+        public bool IsMap => FieldType == FieldType.Message && messageType.IsMapEntry;
 
         /// <summary>
         /// Returns <c>true</c> if this field is a packed, repeated field; <c>false</c> otherwise.
@@ -379,7 +379,12 @@ namespace Google.Protobuf.Reflection
                 IDescriptor typeDescriptor =
                     File.DescriptorPool.LookupSymbol(Proto.TypeName, this);
 
-                // TODO: See how much of this is actually required.
+                // In most cases, the type will be specified in the descriptor proto. This may be
+                // guaranteed in descriptor.proto in the future (with respect to spring 2024), but
+                // we may still see older descriptors created by old versions of protoc, and there
+                // may be some code creating descriptor protos directly. This code effectively
+                // maintains backward compatibility, but we don't expect it to be a path taken
+                // often at all.
                 if (!Proto.HasType)
                 {
                     // Choose field type based on symbol.
diff --git a/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs b/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs
index 911bef56ca..b4b69ad6e3 100644
--- a/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs
+++ b/csharp/src/Google.Protobuf/Reflection/MessageDescriptor.cs
@@ -119,6 +119,7 @@ namespace Google.Protobuf.Reflection
                 DescriptorProto.FieldFieldNumber => (IReadOnlyList<DescriptorBase>)fieldsInDeclarationOrder,
                 DescriptorProto.NestedTypeFieldNumber => (IReadOnlyList<DescriptorBase>)NestedTypes,
                 DescriptorProto.EnumTypeFieldNumber => (IReadOnlyList<DescriptorBase>)EnumTypes,
+                DescriptorProto.OneofDeclFieldNumber => (IReadOnlyList<DescriptorBase>)Oneofs,
                 _ => null,
             };
 
@@ -201,6 +202,12 @@ namespace Google.Protobuf.Reflection
         /// </summary>
         internal bool IsWrapperType => File.Package == "google.protobuf" && File.Name == "google/protobuf/wrappers.proto";
 
+        /// <summary>
+        /// Returns whether this message was synthetically-created to store key/value pairs in a
+        /// map field.
+        /// </summary>
+        public bool IsMapEntry => Proto.Options?.MapEntry == true;
+
         /// <value>
         /// If this is a nested type, get the outer descriptor, otherwise null.
         /// </value>
diff --git a/docs/design/editions/README.md b/docs/design/editions/README.md
index 546fed8605..7ad8674677 100644
--- a/docs/design/editions/README.md
+++ b/docs/design/editions/README.md
@@ -37,4 +37,5 @@ The following topics are in this repository:
 *   [Edition Naming](edition-naming.md)
 *   [Editions Feature Visibility](editions-feature-visibility.md)
 *   [Legacy Syntax Editions](legacy-syntax-editions.md)
-*   [Editions: Feature Extension Layout](editions-feature-extension-layout.md)
\ No newline at end of file
+*   [Editions: Feature Extension Layout](editions-feature-extension-layout.md)
+*   [Editions: Group Migration Issues](group-migration-issues.md)
\ No newline at end of file
diff --git a/docs/design/editions/group-migration-issues.md b/docs/design/editions/group-migration-issues.md
new file mode 100644
index 0000000000..c41ffb2066
--- /dev/null
+++ b/docs/design/editions/group-migration-issues.md
@@ -0,0 +1,401 @@
+# Editions: Group Migration Issues
+
+**Authors**: [@mkruskal-google](https://github.com/mkruskal-google)
+
+## Summary
+
+Address some unexpected issues in delimited encoding in edition 2023 before its
+OSS release.
+
+## Background
+
+Joshua Humphries reported some well-timed
+[issues](https://github.com/protocolbuffers/protobuf/issues/16239) discovered
+while experimenting with our early release of Edition 2023. He discovered that
+our new message encoding feature piggybacked a bit too much on the old group
+logic, and actually ended up being virtually useless in general.
+
+None of our testing or migrations caught this because they were heavily focused
+on *preserving* old behavior (which is the primary goal of edition 2023).
+Delimited messages structured exactly like proto2 groups (e.g. message and field
+in the same scope with matching names) continued to work exactly as before,
+making it seem like everything was fine.
+
+All of this is especially problematic in light of *Submessages: In Pursuit of a
+More Perfect Encoding* (not available externally yet), which intends to migrate the
+ecosystem to use delimited encoding everywhere. Releasing a semi-broken feature
+as a migration tool to eliminate a deprecated syntax is one thing, but trying to
+push the ecosystem to it is especially bad.
+
+## Overview
+
+The problems here stem from the fact that before edition 2023, the field and
+type name of group fields was guaranteed to always be unique and intuitive.
+Proto2 splits groups into a synthetic nested message with a type name equivalent
+to the group specification (required to be capitalized), and a field name that's
+fully lowercased. For example,
+
+```
+optional group MyGroup = 1 { ... }
+```
+
+would become:
+
+```
+message MyGroup { ... }
+optional MyGroup mygroup = 1;
+```
+
+The casing here is very important, since the transformation is irreversible. We
+can't recover the group name from the field name in general, only if the group
+is a single word.
+
+The problem under edition 2023 is that we've removed the generation of
+synchronized synthetic messages from the language. Users now explicitly define
+messages, and any message field can be marked `DELIMITED`. This means that
+anyone assuming that the type and field name are synchronized could now be
+broken.
+
+### Codegen
+
+While using the field name for generated APIs required less special-casing in
+the generators, the field name ends up producing slightly-less-readable APIs for
+multi-word camelcased groups. The result is that we see a fairly random-seeming
+mix in different generators. Using protoc-explorer (not available externally),
+we find the following:
+
+<table>
+  <tr>
+   <td><strong>Language</strong>
+   </td>
+   <td><strong>Generated APIs</strong>
+   </td>
+   <td><strong>Example proto2 getter</strong>
+   </td>
+  </tr>
+  <tr>
+   <td>C++
+   </td>
+   <td>field
+   </td>
+   <td><code>MyGroup mygroup()</code>
+   </td>
+  </tr>
+  <tr>
+   <td>Java (all)
+   </td>
+   <td>message
+   </td>
+   <td><code>MyGroup getMyGroup()</code>
+   </td>
+  </tr>
+  <tr>
+   <td>Python
+   </td>
+   <td>field
+   </td>
+   <td><code>mygroup</code>
+   </td>
+  </tr>
+  <tr>
+   <td>Go (all)
+   </td>
+   <td>field
+   </td>
+   <td><code>GetMygroup() *Foo_MyGroup</code>
+   </td>
+  </tr>
+  <tr>
+   <td>Dart V1
+   </td>
+   <td>field/message*
+   </td>
+   <td><code>get mygroup</code>
+   </td>
+  </tr>
+  <tr>
+   <td>upb **
+   </td>
+   <td>field
+   </td>
+   <td><code>Foo_mygroup()</code>
+   </td>
+  </tr>
+  <tr>
+   <td>Objective-c
+   </td>
+   <td>message
+   </td>
+   <td><code>MyGroup* myGroup</code>
+   </td>
+  </tr>
+  <tr>
+   <td>Swift
+   </td>
+   <td>message
+   </td>
+   <td><code>MyGroup myGroup</code>
+   </td>
+  </tr>
+  <tr>
+   <td>C#
+   </td>
+   <td>field/message*
+   </td>
+   <td><code>MyGroup Mygroup</code>
+   </td>
+  </tr>
+</table>
+
+\* This codegen difference was [caught](cl/611144002) during the implementation
+and intentionally "fixed" in Edition 2023. \
+\*\* This includes all upb-based runtimes as well (e.g. Ruby, Rust, etc.) \
+† Extensions use field
+
+In the Dart V1 implementation, we decided to intentionally introduce a behavior
+change on editions upgrades. It was determined that this only affected a handful
+of protos in google3, and could probably be manually fixed as-needed. Java's
+handling changes the story significantly, since over 50% of protos in google3
+produce generated Java code. Objective-C is also noteworthy since we open-source
+it, and Swift because it's widely used in OSS and we don't own it.
+
+While the editions upgrade is still non-breaking, it means that the generated
+APIs could have very surprising spellings and may not be unique. For example,
+using the same type for two delimited fields in the same containing message will
+create two sets of generated APIs with the same name in some languages!
+
+### Text Format
+
+Our "official"
+[draft specification](https://protobuf.dev/reference/protobuf/textformat-spec/)
+of text-format explicitly states that group messages are encoded by the *message
+name*, rather than the lowercases field name. A group `MyGroup` will be
+serialized as:
+
+```
+MyGroup {
+  ...
+}
+```
+
+In C++, we always serialize the message name and have special handling to only
+accept the message name in parsing. We also have conformance tests locking down
+the positive path here (i.e. using the message name round-trip). The negative
+path (i.e. failing to accept the field name) doesn't have a conformance test,
+but C++/Java/Python all agree and there's no known case that doesn't.
+
+To make things even stranger, for *extensions* (group fields extending other
+messages), we always use the field name for groups. So as far as group
+extensions are concerned, there's no problem for editions.
+
+There are a few problems with non-extension group fields in editions:
+
+*   Refactoring the message name will change any text-format output
+*   New delimited fields will have unexpected text-format output, that *could*
+    conflict with other fields
+*   Text parsers will expect the message name, which is surprising and could be
+    impossible to specify uniquely
+
+## Recommendation
+
+Clearly the end-state we want is for the field name to be used in all generated
+APIs, and for text-format serialization/parsing. The only questions are: how do
+we get there and can/should we do it in time for the 2023 release in 27.0 next
+month?
+
+We propose a combination of the alternatives listed below.
+[Smooth Extension](#smooth-extension) seems like the best short-term path
+forward to unblock the delimited migration. It *mostly* solves the problem and
+doesn't require any new features. The necessary changes for this approach have
+already been prepared, along with new conformance tests to lock down the
+behavior changes.
+
+[Global Feature](#global-feature) is a good long-term mitigation for tech debt
+we're leaving behind with *Smooth Extension*. Ultimately we would like to remove
+any labeling of fields by their type, and editions provides a good mechanism to
+do this. Alternatively, we could implement [aliases](#aliases) and use that to
+unify this old behavior and avoid a new feature. Either of these options will be
+the next step after the release of 2023, with aliases being preferred as long as
+the timing works out.
+
+If we hit any unexpected delays, Nerf Delimited Encoding in 2023 (not available
+externally) is the quickest path forward to unblock the release of edition 2023.
+It has a lot of downsides though, and will block any migration towards delimited
+encoding until edition 2024 has started rolling out.
+
+## Alternatives
+
+### Smooth Extension {#smooth-extension}
+
+Instead of trying to change the existing behavior, we could expand the current
+spec to try to cover both proto2 and editions. We would define a "group-like"
+concept, which applies to all fields which:
+
+*   Have `DELIMITED` encoding
+*   Have a type corresponding to a nested message directly under its containing
+    message
+*   Have a name corresponding to its lowercased type name.
+
+Note that proto2 groups will *always* be "group-like."
+
+For any group-like field we will use the old proto2 semantics, whatever they are
+today. Otherwise, we will treat them as regular fields for both codegen and
+text-format. This means that *most* new cases of delimited encoding will have
+the desired behavior, while *all* old groups will continue to function. The main
+exception here is that users will see the unexpected proto2 behavior if they
+have message/field names that *happen* to match.
+
+While the old behavior will result in some unexpected capitalization when it's
+hit, it's mostly safe. Because of 2 and 3 (and the fact that we disallow
+duplicate field names), we can guarantee that in both codegen and text encoding
+there will never be any conflicting symbols. There can never be two delimited
+fields of the same type using the old behavior, and no other messages or fields
+will exist with either spelling.
+
+Additionally, we will update the text parsers to accept **both** the old
+message-based spelling and the new field-based spelling for group-like fields.
+This will at least prevent parsing failures if users hit this unexpected change
+in behavior.
+
+#### Pros
+
+*   Fully supports old proto2 behavior
+*   Treats most new editions fields correctly
+*   Doesn't allow for any of the problematic cases we see today
+*   By updating the parsers to accept both, we have a migration path to change
+    the "wire"-format
+*   Decoupled from editions launch (since it's a non-breaking change w/o a
+    feature)
+
+#### Cons
+
+*   Requires coordinated changes in every editions-compatible runtime (and many
+    generators)
+*   Keeps the old proto2 behavior around indefinitely, with no path to remove it
+*   Plants surprising edge case for users if they happen to name their
+    message/fields a certain way
+
+### Global Feature {#global-feature}
+
+The simplest answer here is to introduce a new global message feature
+`legacy_group_handling` to control all the changes we'd like. This will only be
+applicable to group-like fields (see
+[Smooth Extension](?tab=t.0#heading=h.blnhard1tpyx)). With this feature enabled,
+these fields will always use their message name for text-format. Each
+non-conformant language could also use this feature to gate the codegen rules.
+
+#### Pros
+
+*   Simple boolean to gate all the behavior changes
+*   Doesn't require adding language features to a bunch of languages that don't
+    have them yet
+*   Uses editions to ratchet down the bad behavior
+
+#### Cons
+
+*   It's a little late in the game to be introducing new features to 2023
+    (go/edition-lifetimes)
+*   Requires coordinated changes in every editions-compatible runtime (and many
+    generators)
+*   The migration story for users is unclear. Overriding the value of this
+    feature is both a "wire"-breaking and API-breaking change they may not be
+    able to do easily.
+*   With the feature set, users will still see all of the problems we have today
+
+### Feature Suite
+
+An extension of [Global feature](?tab=t.0#heading=h.mvtf74vplkdg) would be to
+split the codegen changes out into separate per-language features.
+
+#### Pros
+
+*   Simple booleans to gate all the distinct behavior changes
+*   Uses editions to ratchet down the bad behavior
+*   Better migration story for users, since it separates API and "wire" breaking
+    changes
+
+#### Cons
+
+*   Requires a whole slew of new language features, which typically have a
+    difficult first-time setup
+*   Requires coordinated changes in every editions-compatible runtime (and many
+    generators)
+*   Increases the complexity of edition 2023 significantly
+*   With the features set, users will still see all of the problems we have
+    today
+
+### Nerf Delimited Encoding in 2023
+
+A quick fix to avoid releasing a bad feature would be to simply ban the case
+where the message and field names don't match. Adding this validation to protoc
+would cover the majority of cases, although we might want additional checks in
+every language that supports dynamic messages.
+
+This is a good fallback option if we can't implement anything better before 27.0
+is released. It allows us to release editions in a reasonable state, where we
+can fix these issues and release a more functional `DELIMITED` feature in 2024.
+
+#### Pros
+
+*   Unblocks editions rollout
+*   Easy and safe to implement
+*   Avoids rushed implementation of a proper fix
+*   Avoids runtime issues with text format
+*   Avoids unexpected build breakages post-editions (e.g. renaming the nested
+    message)
+
+#### Cons
+
+*   We'd still be releasing a really bad feature. Instead of opening up new
+    possibilities, it's just "like groups but worse"
+*   We couldn't fix this in 2023 without potential version skew from third party
+    plugins. We'd likely have to wait until edition 2024
+*   Might requires coordinated changes in a lot of runtimes
+*   Doesn't unblock our effort to roll out delimited
+
+### Rename Fields in Editions
+
+While it might be tempting to leverage the edition 2023 upgrade as a place we
+can just rename the group field, that doesn't actually work (e.g. rename
+`mygroup` to `my_group`). Because so many runtimes already use the *field name*
+in generated APIs, they would break under this transformation.
+
+#### Pros
+
+*   Works really well for text-format and some languages
+
+#### Cons
+
+*   Turns 2023 upgrade into a breaking change for many languages
+
+### Aliases {#aliases}
+
+We've discussed aliases a lot mostly in the context of `Any`, but they would be
+useful for any encoding scheme that locks down field/message names. If we had a
+fully implemented alias system in place, it would be the perfect mitigation
+here. Unfortunately, we don't yet and the timeline here is probably too tight to
+implement one.
+
+#### Pros
+
+*   Fixes all of the problems mentioned above
+*   Allows us to specify the old behavior using the proto language, which allows
+    it to be handled by Prototiller
+
+#### Cons
+
+*   We want this to be a real fully thought-out feature, not a hack rushed into
+    a tight timeline
+
+### Do Nothing
+
+Doing nothing doesn't actually break anyone, but it is embarrassing.
+
+#### Pros
+
+*   Easy to do
+
+#### Cons
+
+*   Releases a horrible feature full of foot-guns in our first edition
+*   Doesn't unblock our effort to roll out delimited
diff --git a/docs/third_party.md b/docs/third_party.md
index fce383aa48..6076f9aa64 100644
--- a/docs/third_party.md
+++ b/docs/third_party.md
@@ -187,6 +187,7 @@ Inactive:
         [![Maven Central](https://img.shields.io/maven-central/v/org.xolstice.maven.plugins/protobuf-maven-plugin.svg)](https://repo1.maven.org/maven2/org/xolstice/maven/plugins/protobuf-maven-plugin/)
     *   https://code.google.com/p/maven-protoc-plugin/
     *   https://github.com/os72/protoc-jar-maven-plugin
+    *   https://ascopes.github.io/protobuf-maven-plugin
 *   [Protobuf Plugin for Gradle](https://github.com/google/protobuf-gradle-plugin)
 *   [Sbt plugin for Protocol Buffers](https://github.com/Atry/sbt-cppp)
 
diff --git a/editions/BUILD b/editions/BUILD
index 2cfd511e61..09838afc80 100644
--- a/editions/BUILD
+++ b/editions/BUILD
@@ -1,5 +1,5 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
-load("//:protobuf.bzl", "internal_objc_proto_library", "internal_py_proto_library")
+load("//:protobuf.bzl", "internal_objc_proto_library", "internal_php_proto_library", "internal_py_proto_library")
 load("//bazel:cc_proto_library.bzl", "cc_proto_library")
 load("//bazel:upb_proto_library.bzl", "upb_c_proto_library", "upb_proto_reflection_library")
 load(":defaults.bzl", "compile_edition_defaults", "embed_edition_defaults")
@@ -236,6 +236,31 @@ java_lite_proto_library(
     deps = [":test_messages_proto3_editions_proto"],
 )
 
+internal_php_proto_library(
+    name = "test_messages_proto3_editions_php_proto",
+    testonly = 1,
+    srcs = ["golden/test_messages_proto3_editions.proto"],
+    outs = [
+        "GPBMetadata/TestMessagesProto3Editions.php",
+        "Protobuf_test_messages/Editions/Proto3/EnumOnlyProto3.php",
+        "Protobuf_test_messages/Editions/Proto3/EnumOnlyProto3/PBBool.php",
+        "Protobuf_test_messages/Editions/Proto3/ForeignEnum.php",
+        "Protobuf_test_messages/Editions/Proto3/ForeignMessage.php",
+        "Protobuf_test_messages/Editions/Proto3/NullHypothesisProto3.php",
+        "Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3.php",
+        "Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3/AliasedEnum.php",
+        "Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3/NestedEnum.php",
+        "Protobuf_test_messages/Editions/Proto3/TestAllTypesProto3/NestedMessage.php",
+    ],
+    enable_editions = True,
+    includes = [
+        "golden",
+        "src",
+    ],
+    proto_deps = ["//:well_known_protos"],
+    visibility = ["//conformance:__pkg__"],
+)
+
 internal_py_proto_library(
     name = "test_messages_proto3_editions_py_pb2",
     testonly = True,
@@ -260,7 +285,7 @@ upb_proto_reflection_library(
     deps = ["test_messages_proto3_editions_proto"],
 )
 
-# Export these for conformance tests for ruby codegen.
+# Export these for conformance tests for ruby and C# codegen.
 exports_files(
     [
         "golden/test_messages_proto2_editions.proto",
@@ -268,6 +293,7 @@ exports_files(
     ],
     visibility = [
         "//ruby:__pkg__",
+        "//src/google/protobuf/csharp:__pkg__",
     ],
 )
 
diff --git a/editions/golden/compare_cpp_codegen_failure.txt b/editions/golden/compare_cpp_codegen_failure.txt
index 03be36fe32..27ef82e033 100644
--- a/editions/golden/compare_cpp_codegen_failure.txt
+++ b/editions/golden/compare_cpp_codegen_failure.txt
@@ -25,14 +25,14 @@
      target = ::proto2::internal::WireFormatLite::
          WriteInt32ToArrayWithField<1>(
 @@ @@
-   // Prevent compiler warnings about cached_has_bits being unused
-   (void) cached_has_bits;
+   (void)cached_has_bits;
  
--  // optional int32 int32_field = 1;
-+  // int32 int32_field = 1;
-   cached_has_bits = _impl_._has_bits_[0];
-   if (cached_has_bits & 0x00000001u) {
-     total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+    {
+-    // optional int32 int32_field = 1;
++    // int32 int32_field = 1;
+     cached_has_bits = _impl_._has_bits_[0];
+     if (cached_has_bits & 0x00000001u) {
+       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
 [  FAILED  ] third_party/protobuf/editions/golden/simple_proto3.pb.cc
 [ RUN      ] third_party/protobuf/editions/golden/simple_proto3.pb.h
 @@ @@
diff --git a/editions/golden/compare_cpp_codegen_failure.xml b/editions/golden/compare_cpp_codegen_failure.xml
index 5c96f33eea..af8c9d0432 100644
--- a/editions/golden/compare_cpp_codegen_failure.xml
+++ b/editions/golden/compare_cpp_codegen_failure.xml
@@ -2,10 +2,10 @@
 <testsuites tests="1" name="AllTests">
 <testsuite name="EditionsCodegenTests">
 <testcase name="third_party/protobuf/editions/golden/simple_proto3.pb.cc" status="run" result="completed" classname="DiffTest">
-<failure message="Value of: third_party/protobuf/editions/golden/simple_proto3.pb.cc&#x0A;Expected: &#x0A;// Generated by the protocol buffer compiler.  DO NOT EDIT!&#x0A;// NO CHECKED-IN PROTOBUF GENCODE&#x0A;// source: third_party/protobuf/editions/golden/simple_proto3.proto&#x0A;// Protobuf C++ Version: 0.20240410.0&#x0A;&#x0A;#include &quot;third_party/protobuf/editions/golden/simple_proto3.pb.h&quot;&#x0A;&#x0A;#include &lt;algorithm&gt;&#x0A;#include &lt;type_traits&gt;&#x0A;#include &quot;third_party/protobuf/io/coded_stream.h&quot;&#x0A;#include &quot;third_party/protobuf/generated_message_tctable_impl.h&quot;&#x0A;#include &quot;third_party/protobuf/extension_set.h&quot;&#x0A;#include &quot;third_party/protobuf/wire_format_lite.h&quot;&#x0A;#include &quot;third_party/protobuf/io/zero_copy_stream_impl_lite.h&quot;&#x0A;// @@protoc_insertion_point(includes)&#x0A;&#x0A;// Must be included last.&#x0A;, with the difference:&#x0A;@@ @@&#x0A;     ::_pbi::TcParser::GetTable&lt;::protobuf_editions_test::golden::SimpleProto3&gt;(),  // to_prefetch&#x0A;     #endif  // PROTOBUF_PREFETCH_PARSE_TABLE&#x0A;   }, {{&#x0A;-    // optional int32 int32_field = 1;&#x0A;+    // int32 int32_field = 1;&#x0A;     {::_pbi::TcParser::FastV32S1,&#x0A;      {8, 0, 0, PROTOBUF_FIELD_OFFSET(SimpleProto3, _impl_.int32_field_)}},&#x0A;   }}, {{&#x0A;     65535, 65535&#x0A;   }}, {{&#x0A;-    // optional int32 int32_field = 1;&#x0A;+    // int32 int32_field = 1;&#x0A;     {PROTOBUF_FIELD_OFFSET(SimpleProto3, _impl_.int32_field_), _Internal::kHasBitsOffset + 0, 0,&#x0A;     (0 | ::_fl::kFcOptional | ::_fl::kInt32)},&#x0A;   }},&#x0A;@@ @@&#x0A;   (void)cached_has_bits;&#x0A; &#x0A;   cached_has_bits = _impl_._has_bits_[0];&#x0A;-  // optional int32 int32_field = 1;&#x0A;+  // int32 int32_field = 1;&#x0A;   if (cached_has_bits &amp; 0x00000001u) {&#x0A;     target = ::proto2::internal::WireFormatLite::&#x0A;         WriteInt32ToArrayWithField&lt;1&gt;(&#x0A;@@ @@&#x0A;   // Prevent compiler warnings about cached_has_bits being unused&#x0A;   (void) cached_has_bits;&#x0A; &#x0A;-  // optional int32 int32_field = 1;&#x0A;+  // int32 int32_field = 1;&#x0A;   cached_has_bits = _impl_._has_bits_[0];&#x0A;   if (cached_has_bits &amp; 0x00000001u) {&#x0A;     total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(" type=""></failure>
+<failure message="Value of: third_party/protobuf/editions/golden/simple_proto3.pb.cc&#x0A;Expected: &#x0A;// Generated by the protocol buffer compiler.  DO NOT EDIT!&#x0A;// NO CHECKED-IN PROTOBUF GENCODE&#x0A;// source: third_party/protobuf/editions/golden/simple_proto3.proto&#x0A;// Protobuf C++ Version: 0.20240502.0&#x0A;&#x0A;#include &quot;third_party/protobuf/editions/golden/simple_proto3.pb.h&quot;&#x0A;&#x0A;#include &lt;algorithm&gt;&#x0A;#include &lt;type_traits&gt;&#x0A;#include &quot;third_party/protobuf/io/coded_stream.h&quot;&#x0A;#include &quot;third_party/protobuf/generated_message_tctable_impl.h&quot;&#x0A;#include &quot;third_party/protobuf/extension_set.h&quot;&#x0A;#include &quot;third_party/protobuf/wire_format_lite.h&quot;&#x0A;#include &quot;third_party/protobuf/io/zero_copy_stream_impl_lite.h&quot;&#x0A;// @@protoc_insertion_point(includes)&#x0A;&#x0A;// Must be included last.&#x0A;, with the difference:&#x0A;@@ @@&#x0A;     ::_pbi::TcParser::GetTable&lt;::protobuf_editions_test::golden::SimpleProto3&gt;(),  // to_prefetch&#x0A;     #endif  // PROTOBUF_PREFETCH_PARSE_TABLE&#x0A;   }, {{&#x0A;-    // optional int32 int32_field = 1;&#x0A;+    // int32 int32_field = 1;&#x0A;     {::_pbi::TcParser::FastV32S1,&#x0A;      {8, 0, 0, PROTOBUF_FIELD_OFFSET(SimpleProto3, _impl_.int32_field_)}},&#x0A;   }}, {{&#x0A;     65535, 65535&#x0A;   }}, {{&#x0A;-    // optional int32 int32_field = 1;&#x0A;+    // int32 int32_field = 1;&#x0A;     {PROTOBUF_FIELD_OFFSET(SimpleProto3, _impl_.int32_field_), _Internal::kHasBitsOffset + 0, 0,&#x0A;     (0 | ::_fl::kFcOptional | ::_fl::kInt32)},&#x0A;   }},&#x0A;@@ @@&#x0A;   (void)cached_has_bits;&#x0A; &#x0A;   cached_has_bits = _impl_._has_bits_[0];&#x0A;-  // optional int32 int32_field = 1;&#x0A;+  // int32 int32_field = 1;&#x0A;   if (cached_has_bits &amp; 0x00000001u) {&#x0A;     target = ::proto2::internal::WireFormatLite::&#x0A;         WriteInt32ToArrayWithField&lt;1&gt;(&#x0A;@@ @@&#x0A;   (void)cached_has_bits;&#x0A; &#x0A;    {&#x0A;-    // optional int32 int32_field = 1;&#x0A;+    // int32 int32_field = 1;&#x0A;     cached_has_bits = _impl_._has_bits_[0];&#x0A;     if (cached_has_bits &amp; 0x00000001u) {&#x0A;       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(" type=""></failure>
 </testcase>
 <testcase name="third_party/protobuf/editions/golden/simple_proto3.pb.h" status="run" result="completed" classname="DiffTest">
-<failure message="Value of: third_party/protobuf/editions/golden/simple_proto3.pb.h&#x0A;Expected: &#x0A;// Generated by the protocol buffer compiler.  DO NOT EDIT!&#x0A;// NO CHECKED-IN PROTOBUF GENCODE&#x0A;// source: third_party/protobuf/editions/golden/simple_proto3.proto&#x0A;// Protobuf C++ Version: 0.20240410.0&#x0A;&#x0A;#ifndef GOOGLE_PROTOBUF_INCLUDED_third_5fparty_2fprotobuf_2feditions_2fgolden_2fsimple_5fproto3_2eproto_2epb_2eh&#x0A;#define GOOGLE_PROTOBUF_INCLUDED_third_5fparty_2fprotobuf_2feditions_2fgolden_2fsimple_5fproto3_2eproto_2epb_2eh&#x0A;&#x0A;#include &lt;limits&gt;&#x0A;#include &lt;string&gt;&#x0A;#include &lt;type_traits&gt;&#x0A;#include &lt;utility&gt;&#x0A;&#x0A;#include &quot;third_party/protobuf/runtime_version.h&quot;&#x0A;#if PROTOBUF_VERSION != 20240410&#x0A;#error &quot;Protobuf C++ gencode is built with an incompatible version of&quot;&#x0A;#error &quot;Protobuf C++ headers/runtime. See&quot;&#x0A;#error &quot;https://protobuf.dev/support/cross-version-runtime-guarantee/#cpp&quot;&#x0A;#endif&#x0A;#include &quot;third_party/protobuf/io/coded_stream.h&quot;&#x0A;#include &quot;third_party/protobuf/arena.h&quot;&#x0A;#include &quot;third_party/protobuf/arenastring.h&quot;&#x0A;#include &quot;third_party/protobuf/generated_message_tctable_decl.h&quot;&#x0A;#include &quot;third_party/protobuf/generated_message_util.h&quot;&#x0A;#include &quot;third_party/protobuf/metadata_lite.h&quot;&#x0A;#include &quot;third_party/protobuf/message_lite.h&quot;&#x0A;// @@protoc_insertion_point(includes)&#x0A;&#x0A;// Must be included last.&#x0A;&#x0A;#endif  // GOOGLE_PROTOBUF_INCLUDED_third_5fparty_2fprotobuf_2feditions_2fgolden_2fsimple_5fproto3_2eproto_2epb_2eh&#x0A;, with the difference:&#x0A;@@ @@&#x0A;   enum : int {&#x0A;     kInt32FieldFieldNumber = 1,&#x0A;   };&#x0A;-  // optional int32 int32_field = 1;&#x0A;+  // int32 int32_field = 1;&#x0A;   bool has_int32_field() const;&#x0A;   void clear_int32_field() ;&#x0A;   ::int32_t int32_field() const;&#x0A;@@ @@&#x0A; &#x0A; // SimpleProto3&#x0A; &#x0A;-// optional int32 int32_field = 1;&#x0A;+// int32 int32_field = 1;&#x0A; inline bool SimpleProto3::has_int32_field() const {&#x0A;   bool value = (_impl_._has_bits_[0] &amp; 0x00000001u) != 0;&#x0A;   return value;" type=""></failure>
+<failure message="Value of: third_party/protobuf/editions/golden/simple_proto3.pb.h&#x0A;Expected: &#x0A;// Generated by the protocol buffer compiler.  DO NOT EDIT!&#x0A;// NO CHECKED-IN PROTOBUF GENCODE&#x0A;// source: third_party/protobuf/editions/golden/simple_proto3.proto&#x0A;// Protobuf C++ Version: 0.20240502.0&#x0A;&#x0A;#ifndef GOOGLE_PROTOBUF_INCLUDED_third_5fparty_2fprotobuf_2feditions_2fgolden_2fsimple_5fproto3_2eproto_2epb_2eh&#x0A;#define GOOGLE_PROTOBUF_INCLUDED_third_5fparty_2fprotobuf_2feditions_2fgolden_2fsimple_5fproto3_2eproto_2epb_2eh&#x0A;&#x0A;#include &lt;limits&gt;&#x0A;#include &lt;string&gt;&#x0A;#include &lt;type_traits&gt;&#x0A;#include &lt;utility&gt;&#x0A;&#x0A;#include &quot;third_party/protobuf/runtime_version.h&quot;&#x0A;#if PROTOBUF_VERSION != 20240502&#x0A;#error &quot;Protobuf C++ gencode is built with an incompatible version of&quot;&#x0A;#error &quot;Protobuf C++ headers/runtime. See&quot;&#x0A;#error &quot;https://protobuf.dev/support/cross-version-runtime-guarantee/#cpp&quot;&#x0A;#endif&#x0A;#include &quot;third_party/protobuf/io/coded_stream.h&quot;&#x0A;#include &quot;third_party/protobuf/arena.h&quot;&#x0A;#include &quot;third_party/protobuf/arenastring.h&quot;&#x0A;#include &quot;third_party/protobuf/generated_message_tctable_decl.h&quot;&#x0A;#include &quot;third_party/protobuf/generated_message_util.h&quot;&#x0A;#include &quot;third_party/protobuf/metadata_lite.h&quot;&#x0A;#include &quot;third_party/protobuf/message_lite.h&quot;&#x0A;// @@protoc_insertion_point(includes)&#x0A;&#x0A;// Must be included last.&#x0A;&#x0A;#endif  // GOOGLE_PROTOBUF_INCLUDED_third_5fparty_2fprotobuf_2feditions_2fgolden_2fsimple_5fproto3_2eproto_2epb_2eh&#x0A;, with the difference:&#x0A;@@ @@&#x0A;   enum : int {&#x0A;     kInt32FieldFieldNumber = 1,&#x0A;   };&#x0A;-  // optional int32 int32_field = 1;&#x0A;+  // int32 int32_field = 1;&#x0A;   bool has_int32_field() const;&#x0A;   void clear_int32_field() ;&#x0A;   ::int32_t int32_field() const;&#x0A;@@ @@&#x0A; &#x0A; // SimpleProto3&#x0A; &#x0A;-// optional int32 int32_field = 1;&#x0A;+// int32 int32_field = 1;&#x0A; inline bool SimpleProto3::has_int32_field() const {&#x0A;   bool value = (_impl_._has_bits_[0] &amp; 0x00000001u) != 0;&#x0A;   return value;" type=""></failure>
 </testcase>
 <testcase name="third_party/protobuf/editions/golden/simple_proto3.proto.static_reflection.h" status="run" result="completed" classname="DiffTest">
 </testcase>
diff --git a/editions/golden/editions_transform_proto2.proto b/editions/golden/editions_transform_proto2.proto
index 260a8d26ae..84807b6d59 100644
--- a/editions/golden/editions_transform_proto2.proto
+++ b/editions/golden/editions_transform_proto2.proto
@@ -15,7 +15,7 @@ edition = "2023";
 package protobuf_editions_test;
 
 import "net/proto/proto1_features.proto";
-import "third_party/java/protobuf/java_features.proto";
+import "google/protobuf/java_features.proto";
 import "google/protobuf/cpp_features.proto";
 import "google/protobuf/editions/proto/editions_transform_proto3.proto";
 
diff --git a/examples/.bazelrc b/examples/.bazelrc
index 554440cfe3..f37d75bc21 100644
--- a/examples/.bazelrc
+++ b/examples/.bazelrc
@@ -1 +1,9 @@
-build --cxxopt=-std=c++14 --host_cxxopt=-std=c++14
+common --enable_platform_specific_config
+
+build:linux --cxxopt=-std=c++14 --host_cxxopt=-std=c++14
+build:macos --cxxopt=-std=c++14 --host_cxxopt=-std=c++14
+
+common:windows --enable_runfiles
+
+build --experimental_remote_cache_eviction_retries=5
+build --remote_download_outputs=all
diff --git a/java/README.md b/java/README.md
index bedd7a580f..a6d9a6316c 100644
--- a/java/README.md
+++ b/java/README.md
@@ -67,8 +67,36 @@ If you are contributing code to protobuf or want to use a protobuf version
 that hasn't been officially released yet, you can follow the instructions
 below to build protobuf from source code.
 
+### Build from Source
+
+You may follow these instructions to build from source. This does not require
+Maven to be installed. Note that these instructions skip running unit tests and
+only describes how to install the core protobuf library (without the util
+package).
+
+1) Build the C++ code, or obtain a binary distribution of protoc (see
+   the toplevel [README.md](../README.md)). If you install a binary
+   distribution, make sure that it is the same version as this package.
+   If in doubt, run:
+
+     $ protoc --version
+
+   If you built the C++ code without installing, the compiler binary
+   should be located in ../src.
+
+2) Invoke protoc to build DescriptorProtos.java:
+
+     $ protoc --java_out=core/src/main/java -I../src \
+         ../src/google/protobuf/descriptor.proto
+
+3) Compile the code in core/src/main/java using whatever means you prefer.
+
+4) Install the classes wherever you prefer.
+
 ### Build from Source - With Maven
 
+WARNING: Building from source with Maven is deprecated and will be removed in the 4.28.x release.
+
 1) Install Apache Maven if you don't have it:
 
      http://maven.apache.org/
@@ -109,31 +137,6 @@ The above instructions will install 2 maven artifacts:
                         as well as utilities to work with proto3 well-known
                         types.
 
-### Build from Source - Without Maven
-
-If you would rather not install Maven to build the library, you may
-follow these instructions instead.  Note that these instructions skip
-running unit tests and only describes how to install the core protobuf
-library (without the util package).
-
-1) Build the C++ code, or obtain a binary distribution of protoc.  If
-   you install a binary distribution, make sure that it is the same
-   version as this package.  If in doubt, run:
-
-     $ protoc --version
-
-   If you built the C++ code without installing, the compiler binary
-   should be located in ../src.
-
-2) Invoke protoc to build DescriptorProtos.java:
-
-     $ protoc --java_out=core/src/main/java -I../src \
-         ../src/google/protobuf/descriptor.proto
-
-3) Compile the code in core/src/main/java using whatever means you prefer.
-
-4) Install the classes wherever you prefer.
-
 ## Compatibility Notice
 
 * Protobuf minor version releases are backwards-compatible. If your code
diff --git a/java/core/BUILD.bazel b/java/core/BUILD.bazel
index 683b0654ac..bc2b592589 100644
--- a/java/core/BUILD.bazel
+++ b/java/core/BUILD.bazel
@@ -60,6 +60,8 @@ LITE_SRCS = [
     "src/main/java/com/google/protobuf/LazyStringArrayList.java",
     "src/main/java/com/google/protobuf/LazyStringList.java",
     "src/main/java/com/google/protobuf/ListFieldSchema.java",
+    "src/main/java/com/google/protobuf/ListFieldSchemaLite.java",
+    "src/main/java/com/google/protobuf/ListFieldSchemas.java",
     "src/main/java/com/google/protobuf/LongArrayList.java",
     "src/main/java/com/google/protobuf/ManifestSchemaFactory.java",
     "src/main/java/com/google/protobuf/MapEntryLite.java",
@@ -334,6 +336,7 @@ proto_library(
     deps = [
         "//:any_proto",
         "//:descriptor_proto",
+        "//:java_features_proto",
         "//:lite_test_protos",
         "//:wrappers_proto",
         "//src/google/protobuf:generic_test_protos",
@@ -520,6 +523,7 @@ LITE_TEST_EXCLUSIONS = [
     "src/test/java/com/google/protobuf/AnyTest.java",
     "src/test/java/com/google/protobuf/CodedInputStreamTest.java",
     "src/test/java/com/google/protobuf/DeprecatedFieldTest.java",
+    "src/test/java/com/google/protobuf/DebugFormatTest.java",
     "src/test/java/com/google/protobuf/DescriptorsTest.java",
     "src/test/java/com/google/protobuf/DiscardUnknownFieldsTest.java",
     "src/test/java/com/google/protobuf/DynamicMessageTest.java",
diff --git a/java/core/src/main/java/com/google/protobuf/AbstractMessageLite.java b/java/core/src/main/java/com/google/protobuf/AbstractMessageLite.java
index bc643bd15c..dde30c1b7e 100644
--- a/java/core/src/main/java/com/google/protobuf/AbstractMessageLite.java
+++ b/java/core/src/main/java/com/google/protobuf/AbstractMessageLite.java
@@ -397,6 +397,8 @@ public abstract class AbstractMessageLite<
           }
           if (value instanceof ByteString) {
             lazyList.add((ByteString) value);
+          } else if (value instanceof byte[]) {
+            lazyList.add(ByteString.copyFrom((byte[]) value));
           } else {
             lazyList.add((String) value);
           }
diff --git a/java/core/src/main/java/com/google/protobuf/CodedInputStream.java b/java/core/src/main/java/com/google/protobuf/CodedInputStream.java
index 81da417783..6fb96afa4b 100644
--- a/java/core/src/main/java/com/google/protobuf/CodedInputStream.java
+++ b/java/core/src/main/java/com/google/protobuf/CodedInputStream.java
@@ -2690,6 +2690,9 @@ public abstract class CodedInputStream {
         throw InvalidProtocolBufferException.negativeSize();
       }
       byteLimit += totalBytesRetired + pos;
+      if (byteLimit < 0) {
+        throw InvalidProtocolBufferException.parseFailure();
+      }
       final int oldLimit = currentLimit;
       if (byteLimit > oldLimit) {
         throw InvalidProtocolBufferException.truncatedMessage();
diff --git a/java/core/src/main/java/com/google/protobuf/CodedOutputStreamWriter.java b/java/core/src/main/java/com/google/protobuf/CodedOutputStreamWriter.java
index 6c060cc3ab..a20a579e3e 100644
--- a/java/core/src/main/java/com/google/protobuf/CodedOutputStreamWriter.java
+++ b/java/core/src/main/java/com/google/protobuf/CodedOutputStreamWriter.java
@@ -167,6 +167,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeInt32List(int fieldNumber, List<Integer> value, boolean packed)
       throws IOException {
+    if (value instanceof IntArrayList) {
+      writeInt32ListInternal(fieldNumber, (IntArrayList) value, packed);
+    } else {
+      writeInt32ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeInt32ListInternal(int fieldNumber, IntArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeInt32SizeNoTag(value.getInt(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeInt32NoTag(value.getInt(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeInt32(fieldNumber, value.getInt(i));
+      }
+    }
+  }
+
+  private void writeInt32ListInternal(int fieldNumber, List<Integer> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -191,6 +223,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeFixed32List(int fieldNumber, List<Integer> value, boolean packed)
       throws IOException {
+    if (value instanceof IntArrayList) {
+      writeFixed32ListInternal(fieldNumber, (IntArrayList) value, packed);
+    } else {
+      writeFixed32ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeFixed32ListInternal(int fieldNumber, IntArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeFixed32SizeNoTag(value.getInt(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeFixed32NoTag(value.getInt(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeFixed32(fieldNumber, value.getInt(i));
+      }
+    }
+  }
+
+  private void writeFixed32ListInternal(int fieldNumber, List<Integer> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -214,6 +278,38 @@ final class CodedOutputStreamWriter implements Writer {
 
   @Override
   public void writeInt64List(int fieldNumber, List<Long> value, boolean packed) throws IOException {
+    if (value instanceof LongArrayList) {
+      writeInt64ListInternal(fieldNumber, (LongArrayList) value, packed);
+    } else {
+      writeInt64ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeInt64ListInternal(int fieldNumber, LongArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeInt64SizeNoTag(value.getLong(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeInt64NoTag(value.getLong(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeInt64(fieldNumber, value.getLong(i));
+      }
+    }
+  }
+
+  private void writeInt64ListInternal(int fieldNumber, List<Long> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -234,10 +330,41 @@ final class CodedOutputStreamWriter implements Writer {
       }
     }
   }
-
   @Override
   public void writeUInt64List(int fieldNumber, List<Long> value, boolean packed)
       throws IOException {
+    if (value instanceof LongArrayList) {
+      writeUInt64ListInternal(fieldNumber, (LongArrayList) value, packed);
+    } else {
+      writeUInt64ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeUInt64ListInternal(int fieldNumber, LongArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeUInt64SizeNoTag(value.getLong(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeUInt64NoTag(value.getLong(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeUInt64(fieldNumber, value.getLong(i));
+      }
+    }
+  }
+
+  private void writeUInt64ListInternal(int fieldNumber, List<Long> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -262,6 +389,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeFixed64List(int fieldNumber, List<Long> value, boolean packed)
       throws IOException {
+    if (value instanceof LongArrayList) {
+      writeFixed64ListInternal(fieldNumber, (LongArrayList) value, packed);
+    } else {
+      writeFixed64ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeFixed64ListInternal(int fieldNumber, LongArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeFixed64SizeNoTag(value.getLong(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeFixed64NoTag(value.getLong(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeFixed64(fieldNumber, value.getLong(i));
+      }
+    }
+  }
+
+  private void writeFixed64ListInternal(int fieldNumber, List<Long> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -286,6 +445,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeFloatList(int fieldNumber, List<Float> value, boolean packed)
       throws IOException {
+    if (value instanceof FloatArrayList) {
+      writeFloatListInternal(fieldNumber, (FloatArrayList) value, packed);
+    } else {
+      writeFloatListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeFloatListInternal(int fieldNumber, FloatArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeFloatSizeNoTag(value.getFloat(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeFloatNoTag(value.getFloat(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeFloat(fieldNumber, value.getFloat(i));
+      }
+    }
+  }
+
+  private void writeFloatListInternal(int fieldNumber, List<Float> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -310,6 +501,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeDoubleList(int fieldNumber, List<Double> value, boolean packed)
       throws IOException {
+    if (value instanceof DoubleArrayList) {
+      writeDoubleListInternal(fieldNumber, (DoubleArrayList) value, packed);
+    } else {
+      writeDoubleListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeDoubleListInternal(int fieldNumber, DoubleArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeDoubleSizeNoTag(value.getDouble(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeDoubleNoTag(value.getDouble(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeDouble(fieldNumber, value.getDouble(i));
+      }
+    }
+  }
+
+  private void writeDoubleListInternal(int fieldNumber, List<Double> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -334,6 +557,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeEnumList(int fieldNumber, List<Integer> value, boolean packed)
       throws IOException {
+    if (value instanceof IntArrayList) {
+      writeEnumListInternal(fieldNumber, (IntArrayList) value, packed);
+    } else {
+      writeEnumListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeEnumListInternal(int fieldNumber, IntArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeEnumSizeNoTag(value.getInt(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeEnumNoTag(value.getInt(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeEnum(fieldNumber, value.getInt(i));
+      }
+    }
+  }
+
+  private void writeEnumListInternal(int fieldNumber, List<Integer> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -358,6 +613,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeBoolList(int fieldNumber, List<Boolean> value, boolean packed)
       throws IOException {
+    if (value instanceof BooleanArrayList) {
+      writeBoolListInternal(fieldNumber, (BooleanArrayList) value, packed);
+    } else {
+      writeBoolListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeBoolListInternal(int fieldNumber, BooleanArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeBoolSizeNoTag(value.getBoolean(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeBoolNoTag(value.getBoolean(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeBool(fieldNumber, value.getBoolean(i));
+      }
+    }
+  }
+
+  private void writeBoolListInternal(int fieldNumber, List<Boolean> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -411,6 +698,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeUInt32List(int fieldNumber, List<Integer> value, boolean packed)
       throws IOException {
+    if (value instanceof IntArrayList) {
+      writeUInt32ListInternal(fieldNumber, (IntArrayList) value, packed);
+    } else {
+      writeUInt32ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeUInt32ListInternal(int fieldNumber, IntArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeUInt32SizeNoTag(value.getInt(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeUInt32NoTag(value.getInt(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeUInt32(fieldNumber, value.getInt(i));
+      }
+    }
+  }
+
+  public void writeUInt32ListInternal(int fieldNumber, List<Integer> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -435,6 +754,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeSFixed32List(int fieldNumber, List<Integer> value, boolean packed)
       throws IOException {
+    if (value instanceof IntArrayList) {
+      writeSFixed32ListInternal(fieldNumber, (IntArrayList) value, packed);
+    } else {
+      writeSFixed32ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeSFixed32ListInternal(int fieldNumber, IntArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeSFixed32SizeNoTag(value.getInt(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSFixed32NoTag(value.getInt(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSFixed32(fieldNumber, value.getInt(i));
+      }
+    }
+  }
+
+  private void writeSFixed32ListInternal(int fieldNumber, List<Integer> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -459,6 +810,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeSFixed64List(int fieldNumber, List<Long> value, boolean packed)
       throws IOException {
+    if (value instanceof LongArrayList) {
+      writeSFixed64ListInternal(fieldNumber, (LongArrayList) value, packed);
+    } else {
+      writeSFixed64ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeSFixed64ListInternal(int fieldNumber, LongArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeSFixed64SizeNoTag(value.getLong(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSFixed64NoTag(value.getLong(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSFixed64(fieldNumber, value.getLong(i));
+      }
+    }
+  }
+
+  private void writeSFixed64ListInternal(int fieldNumber, List<Long> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -483,6 +866,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeSInt32List(int fieldNumber, List<Integer> value, boolean packed)
       throws IOException {
+    if (value instanceof IntArrayList) {
+      writeSInt32ListInternal(fieldNumber, (IntArrayList) value, packed);
+    } else {
+      writeSInt32ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeSInt32ListInternal(int fieldNumber, IntArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeSInt32SizeNoTag(value.getInt(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSInt32NoTag(value.getInt(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSInt32(fieldNumber, value.getInt(i));
+      }
+    }
+  }
+
+  public void writeSInt32ListInternal(int fieldNumber, List<Integer> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
@@ -507,6 +922,38 @@ final class CodedOutputStreamWriter implements Writer {
   @Override
   public void writeSInt64List(int fieldNumber, List<Long> value, boolean packed)
       throws IOException {
+    if (value instanceof LongArrayList) {
+      writeSInt64ListInternal(fieldNumber, (LongArrayList) value, packed);
+    } else {
+      writeSInt64ListInternal(fieldNumber, value, packed);
+    }
+  }
+
+  private void writeSInt64ListInternal(int fieldNumber, LongArrayList value, boolean packed)
+      throws IOException {
+    if (packed) {
+      output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
+
+      // Compute and write the length of the data.
+      int dataSize = 0;
+      for (int i = 0; i < value.size(); ++i) {
+        dataSize += CodedOutputStream.computeSInt64SizeNoTag(value.getLong(i));
+      }
+      output.writeUInt32NoTag(dataSize);
+
+      // Write the data itself, without any tags.
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSInt64NoTag(value.getLong(i));
+      }
+    } else {
+      for (int i = 0; i < value.size(); ++i) {
+        output.writeSInt64(fieldNumber, value.getLong(i));
+      }
+    }
+  }
+
+  private void writeSInt64ListInternal(int fieldNumber, List<Long> value, boolean packed)
+      throws IOException {
     if (packed) {
       output.writeTag(fieldNumber, WIRETYPE_LENGTH_DELIMITED);
 
diff --git a/java/core/src/main/java/com/google/protobuf/DebugFormat.java b/java/core/src/main/java/com/google/protobuf/DebugFormat.java
new file mode 100644
index 0000000000..2d63ef1719
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/DebugFormat.java
@@ -0,0 +1,79 @@
+package com.google.protobuf;
+
+import com.google.protobuf.Descriptors.FieldDescriptor;
+
+/**
+ * Provides an explicit API for unstable, redacting debug output suitable for debug logging. This
+ * implementation is based on TextFormat, but should not be parsed.
+ */
+public final class DebugFormat {
+
+  private final boolean isSingleLine;
+
+  private DebugFormat(boolean singleLine) {
+    isSingleLine = singleLine;
+  }
+
+  public static DebugFormat singleLine() {
+    return new DebugFormat(true);
+  }
+
+  public static DebugFormat multiline() {
+    return new DebugFormat(false);
+  }
+
+  public String toString(MessageOrBuilder message) {
+    return TextFormat.printer()
+        .emittingSingleLine(this.isSingleLine)
+        .enablingSafeDebugFormat(true)
+        .printToString(message);
+  }
+
+  public String toString(FieldDescriptor field, Object value) {
+    return TextFormat.printer()
+        .emittingSingleLine(this.isSingleLine)
+        .enablingSafeDebugFormat(true)
+        .printFieldToString(field, value);
+  }
+
+  public String toString(UnknownFieldSet fields) {
+    return TextFormat.printer()
+        .emittingSingleLine(this.isSingleLine)
+        .enablingSafeDebugFormat(true)
+        .printToString(fields);
+  }
+
+  public Object lazyToString(MessageOrBuilder message) {
+    return new LazyDebugOutput(message, this);
+  }
+
+  public Object lazyToString(UnknownFieldSet fields) {
+    return new LazyDebugOutput(fields, this);
+  }
+
+  private static class LazyDebugOutput {
+    private final MessageOrBuilder message;
+    private final UnknownFieldSet fields;
+    private final DebugFormat format;
+
+    LazyDebugOutput(MessageOrBuilder message, DebugFormat format) {
+      this.message = message;
+      this.fields = null;
+      this.format = format;
+    }
+
+    LazyDebugOutput(UnknownFieldSet fields, DebugFormat format) {
+      this.message = null;
+      this.fields = fields;
+      this.format = format;
+    }
+
+    @Override
+    public String toString() {
+      if (message != null) {
+        return format.toString(message);
+      }
+      return format.toString(fields);
+    }
+  }
+}
diff --git a/java/core/src/main/java/com/google/protobuf/Descriptors.java b/java/core/src/main/java/com/google/protobuf/Descriptors.java
index f4aa9ca3ba..bba3178614 100644
--- a/java/core/src/main/java/com/google/protobuf/Descriptors.java
+++ b/java/core/src/main/java/com/google/protobuf/Descriptors.java
@@ -94,7 +94,7 @@ public final class Descriptors {
         if (javaEditionDefaults == null) {
           try {
             ExtensionRegistry registry = ExtensionRegistry.newInstance();
-            registry.add(JavaFeaturesProto.java);
+            registry.add(JavaFeaturesProto.java_);
             setTestJavaEditionDefaults(
                 FeatureSetDefaults.parseFrom(
                     JavaEditionDefaults.PROTOBUF_INTERNAL_JAVA_EDITION_DEFAULTS.getBytes(
@@ -679,7 +679,7 @@ public final class Descriptors {
       if (getEdition() == Edition.EDITION_PROTO2) {
         if (proto.getOptions().getJavaStringCheckUtf8()) {
           features.setExtension(
-              JavaFeaturesProto.java,
+              JavaFeaturesProto.java_,
               JavaFeatures.newBuilder()
                   .setUtf8Validation(JavaFeatures.Utf8Validation.VERIFY)
                   .build());
@@ -1320,7 +1320,7 @@ public final class Descriptors {
         return true;
       }
       if (this.features
-          .getExtension(JavaFeaturesProto.java)
+          .getExtension(JavaFeaturesProto.java_)
           .getUtf8Validation()
           .equals(JavaFeatures.Utf8Validation.VERIFY)) {
         return true;
@@ -1577,7 +1577,7 @@ public final class Descriptors {
       }
 
       return getType() == Type.ENUM
-          && (this.features.getExtension(JavaFeaturesProto.java).getLegacyClosedEnum()
+          && (this.features.getExtension(JavaFeaturesProto.java_).getLegacyClosedEnum()
               || enumType.isClosed());
     }
 
diff --git a/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java b/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java
index cd8c852e9e..5f0ce06685 100644
--- a/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java
+++ b/java/core/src/main/java/com/google/protobuf/ExtensionSchemas.java
@@ -31,4 +31,6 @@ final class ExtensionSchemas {
     }
     return FULL_SCHEMA;
   }
+
+  private ExtensionSchemas() {}
 }
diff --git a/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java b/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java
index 115f4288cd..0937114e42 100644
--- a/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java
+++ b/java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java
@@ -1621,10 +1621,17 @@ public abstract class GeneratedMessageLite<
 
   /** A static helper method for parsing a partial from byte array. */
   private static <T extends GeneratedMessageLite<T, ?>> T parsePartialFrom(
-      T instance, byte[] input, int offset, int length, ExtensionRegistryLite extensionRegistry)
+      T defaultInstance,
+      byte[] input,
+      int offset,
+      int length,
+      ExtensionRegistryLite extensionRegistry)
       throws InvalidProtocolBufferException {
+    if (length == 0) {
+      return defaultInstance;
+    }
     @SuppressWarnings("unchecked") // Guaranteed by protoc
-    T result = instance.newMutableInstance();
+    T result = defaultInstance.newMutableInstance();
     try {
       Schema<T> schema = Protobuf.getInstance().schemaFor(result);
       schema.mergeFrom(
diff --git a/java/core/src/main/java/com/google/protobuf/IntArrayList.java b/java/core/src/main/java/com/google/protobuf/IntArrayList.java
index eea507ae8f..e6a1aca1ec 100644
--- a/java/core/src/main/java/com/google/protobuf/IntArrayList.java
+++ b/java/core/src/main/java/com/google/protobuf/IntArrayList.java
@@ -47,7 +47,7 @@ final class IntArrayList extends AbstractProtobufList<Integer>
    */
   private IntArrayList(int[] other, int size, boolean isMutable) {
     super(isMutable);
-    array = other;
+    this.array = other;
     this.size = size;
   }
 
diff --git a/java/core/src/main/java/com/google/protobuf/Internal.java b/java/core/src/main/java/com/google/protobuf/Internal.java
index 3024aa9dfb..07bec5ef29 100644
--- a/java/core/src/main/java/com/google/protobuf/Internal.java
+++ b/java/core/src/main/java/com/google/protobuf/Internal.java
@@ -371,6 +371,36 @@ public final class Internal {
     return ((MessageLite) destination).toBuilder().mergeFrom((MessageLite) source).buildPartial();
   }
 
+  /**
+   * Provides an immutable view of {@code List<T>} around an {@code IntList}.
+   *
+   * <p>Protobuf internal. Used in protobuf generated code only.
+   */
+  public static class IntListAdapter<T> extends AbstractList<T> {
+    /** Convert individual elements of the List from int to T. */
+    public interface IntConverter<T> {
+      T convert(int from);
+    }
+
+    private final IntList fromList;
+    private final IntConverter<T> converter;
+
+    public IntListAdapter(IntList fromList, IntConverter<T> converter) {
+      this.fromList = fromList;
+      this.converter = converter;
+    }
+
+    @Override
+    public T get(int index) {
+      return converter.convert(fromList.getInt(index));
+    }
+
+    @Override
+    public int size() {
+      return fromList.size();
+    }
+  }
+
   /**
    * Provides an immutable view of {@code List<T>} around a {@code List<F>}.
    *
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java
index bc55eb23c7..eaab68b8d3 100644
--- a/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchema.java
@@ -7,162 +7,17 @@
 
 package com.google.protobuf;
 
-import com.google.protobuf.Internal.ProtobufList;
-import java.util.ArrayList;
-import java.util.Collections;
 import java.util.List;
 
 /**
  * Utility class that aids in properly manipulating list fields for either the lite or full runtime.
  */
 @CheckReturnValue
-abstract class ListFieldSchema {
-  // Disallow construction.
-  private ListFieldSchema() {}
+interface ListFieldSchema {
 
-  private static final ListFieldSchema FULL_INSTANCE = new ListFieldSchemaFull();
-  private static final ListFieldSchema LITE_INSTANCE = new ListFieldSchemaLite();
+  <L> List<L> mutableListAt(Object msg, long offset);
 
-  abstract <L> List<L> mutableListAt(Object msg, long offset);
+  void makeImmutableListAt(Object msg, long offset);
 
-  abstract void makeImmutableListAt(Object msg, long offset);
-
-  abstract <L> void mergeListsAt(Object msg, Object otherMsg, long offset);
-
-  static ListFieldSchema full() {
-    return FULL_INSTANCE;
-  }
-
-  static ListFieldSchema lite() {
-    return LITE_INSTANCE;
-  }
-
-  /** Implementation for the full runtime. */
-  private static final class ListFieldSchemaFull extends ListFieldSchema {
-
-    private static final Class<?> UNMODIFIABLE_LIST_CLASS =
-        Collections.unmodifiableList(Collections.emptyList()).getClass();
-
-    @Override
-    <L> List<L> mutableListAt(Object message, long offset) {
-      return mutableListAt(message, offset, AbstractProtobufList.DEFAULT_CAPACITY);
-    }
-
-    @Override
-    void makeImmutableListAt(Object message, long offset) {
-      List<?> list = (List<?>) UnsafeUtil.getObject(message, offset);
-      Object immutable = null;
-      if (list instanceof LazyStringList) {
-        immutable = ((LazyStringList) list).getUnmodifiableView();
-      } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
-        // already immutable
-        return;
-      } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
-        if (((ProtobufList<?>) list).isModifiable()) {
-          ((ProtobufList<?>) list).makeImmutable();
-        }
-        return;
-      } else {
-        immutable = Collections.unmodifiableList((List<?>) list);
-      }
-      UnsafeUtil.putObject(message, offset, immutable);
-    }
-
-    @SuppressWarnings("unchecked")
-    private static <L> List<L> mutableListAt(Object message, long offset, int additionalCapacity) {
-      List<L> list = getList(message, offset);
-      if (list.isEmpty()) {
-        if (list instanceof LazyStringList) {
-          list = (List<L>) new LazyStringArrayList(additionalCapacity);
-        } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
-          list = ((ProtobufList<L>) list).mutableCopyWithCapacity(additionalCapacity);
-        } else {
-          list = new ArrayList<L>(additionalCapacity);
-        }
-        UnsafeUtil.putObject(message, offset, list);
-      } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
-        ArrayList<L> newList = new ArrayList<L>(list.size() + additionalCapacity);
-        newList.addAll(list);
-        list = newList;
-        UnsafeUtil.putObject(message, offset, list);
-      } else if (list instanceof UnmodifiableLazyStringList) {
-        LazyStringArrayList newList = new LazyStringArrayList(list.size() + additionalCapacity);
-        newList.addAll((UnmodifiableLazyStringList) list);
-        list = (List<L>) newList;
-        UnsafeUtil.putObject(message, offset, list);
-      } else if (list instanceof PrimitiveNonBoxingCollection
-          && list instanceof ProtobufList
-          && !((ProtobufList<L>) list).isModifiable()) {
-        list = ((ProtobufList<L>) list).mutableCopyWithCapacity(list.size() + additionalCapacity);
-        UnsafeUtil.putObject(message, offset, list);
-      }
-      return list;
-    }
-
-    @Override
-    <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
-      List<E> other = getList(otherMsg, offset);
-      List<E> mine = mutableListAt(msg, offset, other.size());
-
-      int size = mine.size();
-      int otherSize = other.size();
-      if (size > 0 && otherSize > 0) {
-        mine.addAll(other);
-      }
-
-      List<E> merged = size > 0 ? mine : other;
-      UnsafeUtil.putObject(msg, offset, merged);
-    }
-
-    @SuppressWarnings("unchecked")
-    static <E> List<E> getList(Object message, long offset) {
-      return (List<E>) UnsafeUtil.getObject(message, offset);
-    }
-  }
-
-  /** Implementation for the lite runtime. */
-  private static final class ListFieldSchemaLite extends ListFieldSchema {
-
-    @Override
-    <L> List<L> mutableListAt(Object message, long offset) {
-      ProtobufList<L> list = getProtobufList(message, offset);
-      if (!list.isModifiable()) {
-        int size = list.size();
-        list =
-            list.mutableCopyWithCapacity(
-                size == 0 ? AbstractProtobufList.DEFAULT_CAPACITY : size * 2);
-        UnsafeUtil.putObject(message, offset, list);
-      }
-      return list;
-    }
-
-    @Override
-    void makeImmutableListAt(Object message, long offset) {
-      ProtobufList<?> list = getProtobufList(message, offset);
-      list.makeImmutable();
-    }
-
-    @Override
-    <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
-      ProtobufList<E> mine = getProtobufList(msg, offset);
-      ProtobufList<E> other = getProtobufList(otherMsg, offset);
-
-      int size = mine.size();
-      int otherSize = other.size();
-      if (size > 0 && otherSize > 0) {
-        if (!mine.isModifiable()) {
-          mine = mine.mutableCopyWithCapacity(size + otherSize);
-        }
-        mine.addAll(other);
-      }
-
-      ProtobufList<E> merged = size > 0 ? mine : other;
-      UnsafeUtil.putObject(msg, offset, merged);
-    }
-
-    @SuppressWarnings("unchecked")
-    static <E> ProtobufList<E> getProtobufList(Object message, long offset) {
-      return (ProtobufList<E>) UnsafeUtil.getObject(message, offset);
-    }
-  }
+  <L> void mergeListsAt(Object msg, Object otherMsg, long offset);
 }
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchemaFull.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaFull.java
new file mode 100644
index 0000000000..8f0308ab63
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaFull.java
@@ -0,0 +1,99 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+package com.google.protobuf;
+
+import com.google.protobuf.Internal.ProtobufList;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * Utility class that aids in properly manipulating list fields for either the lite or full runtime.
+ */
+@CheckReturnValue
+final class ListFieldSchemaFull implements ListFieldSchema {
+
+  private static final Class<?> UNMODIFIABLE_LIST_CLASS =
+      Collections.unmodifiableList(Collections.emptyList()).getClass();
+
+  @Override
+  public <L> List<L> mutableListAt(Object message, long offset) {
+    return mutableListAt(message, offset, AbstractProtobufList.DEFAULT_CAPACITY);
+  }
+
+  @SuppressWarnings("unchecked")
+  private static <L> List<L> mutableListAt(Object message, long offset, int additionalCapacity) {
+    List<L> list = getList(message, offset);
+    if (list.isEmpty()) {
+      if (list instanceof LazyStringList) {
+        list = (List<L>) new LazyStringArrayList(additionalCapacity);
+      } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
+        list = ((ProtobufList<L>) list).mutableCopyWithCapacity(additionalCapacity);
+      } else {
+        list = new ArrayList<L>(additionalCapacity);
+      }
+      UnsafeUtil.putObject(message, offset, list);
+    } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
+      ArrayList<L> newList = new ArrayList<L>(list.size() + additionalCapacity);
+      newList.addAll(list);
+      list = newList;
+      UnsafeUtil.putObject(message, offset, list);
+    } else if (list instanceof UnmodifiableLazyStringList) {
+      LazyStringArrayList newList = new LazyStringArrayList(list.size() + additionalCapacity);
+      newList.addAll((UnmodifiableLazyStringList) list);
+      list = (List<L>) newList;
+      UnsafeUtil.putObject(message, offset, list);
+    } else if (list instanceof PrimitiveNonBoxingCollection
+        && list instanceof ProtobufList
+        && !((ProtobufList<L>) list).isModifiable()) {
+      list = ((ProtobufList<L>) list).mutableCopyWithCapacity(list.size() + additionalCapacity);
+      UnsafeUtil.putObject(message, offset, list);
+    }
+    return list;
+  }
+
+  @Override
+  public void makeImmutableListAt(Object message, long offset) {
+    List<?> list = (List<?>) UnsafeUtil.getObject(message, offset);
+    Object immutable = null;
+    if (list instanceof LazyStringList) {
+      immutable = ((LazyStringList) list).getUnmodifiableView();
+    } else if (UNMODIFIABLE_LIST_CLASS.isAssignableFrom(list.getClass())) {
+      // already immutable
+      return;
+    } else if (list instanceof PrimitiveNonBoxingCollection && list instanceof ProtobufList) {
+      if (((ProtobufList<?>) list).isModifiable()) {
+        ((ProtobufList<?>) list).makeImmutable();
+      }
+      return;
+    } else {
+      immutable = Collections.unmodifiableList((List<?>) list);
+    }
+    UnsafeUtil.putObject(message, offset, immutable);
+  }
+
+  @Override
+  public <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
+    List<E> other = getList(otherMsg, offset);
+    List<E> mine = mutableListAt(msg, offset, other.size());
+
+    int size = mine.size();
+    int otherSize = other.size();
+    if (size > 0 && otherSize > 0) {
+      mine.addAll(other);
+    }
+
+    List<E> merged = size > 0 ? mine : other;
+    UnsafeUtil.putObject(msg, offset, merged);
+  }
+
+  @SuppressWarnings("unchecked")
+  static <E> List<E> getList(Object message, long offset) {
+    return (List<E>) UnsafeUtil.getObject(message, offset);
+  }
+}
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchemaLite.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaLite.java
new file mode 100644
index 0000000000..f0cf71ecc0
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchemaLite.java
@@ -0,0 +1,59 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+package com.google.protobuf;
+
+import com.google.protobuf.Internal.ProtobufList;
+import java.util.List;
+
+/**
+ * Utility class that aids in properly manipulating list fields for either the lite or full runtime.
+ */
+final class ListFieldSchemaLite implements ListFieldSchema {
+
+  @Override
+  public <L> List<L> mutableListAt(Object message, long offset) {
+    ProtobufList<L> list = getProtobufList(message, offset);
+    if (!list.isModifiable()) {
+      int size = list.size();
+      list =
+          list.mutableCopyWithCapacity(
+              size == 0 ? AbstractProtobufList.DEFAULT_CAPACITY : size * 2);
+      UnsafeUtil.putObject(message, offset, list);
+    }
+    return list;
+  }
+
+  @Override
+  public void makeImmutableListAt(Object message, long offset) {
+    ProtobufList<?> list = getProtobufList(message, offset);
+    list.makeImmutable();
+  }
+
+  @Override
+  public <E> void mergeListsAt(Object msg, Object otherMsg, long offset) {
+    ProtobufList<E> mine = getProtobufList(msg, offset);
+    ProtobufList<E> other = getProtobufList(otherMsg, offset);
+
+    int size = mine.size();
+    int otherSize = other.size();
+    if (size > 0 && otherSize > 0) {
+      if (!mine.isModifiable()) {
+        mine = mine.mutableCopyWithCapacity(size + otherSize);
+      }
+      mine.addAll(other);
+    }
+
+    ProtobufList<E> merged = size > 0 ? mine : other;
+    UnsafeUtil.putObject(msg, offset, merged);
+  }
+
+  @SuppressWarnings("unchecked")
+  static <E> ProtobufList<E> getProtobufList(Object message, long offset) {
+    return (ProtobufList<E>) UnsafeUtil.getObject(message, offset);
+  }
+}
diff --git a/java/core/src/main/java/com/google/protobuf/ListFieldSchemas.java b/java/core/src/main/java/com/google/protobuf/ListFieldSchemas.java
new file mode 100644
index 0000000000..6250b7a2d7
--- /dev/null
+++ b/java/core/src/main/java/com/google/protobuf/ListFieldSchemas.java
@@ -0,0 +1,33 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+package com.google.protobuf;
+
+@CheckReturnValue
+final class ListFieldSchemas {
+  private static final ListFieldSchema FULL_SCHEMA = loadSchemaForFullRuntime();
+  private static final ListFieldSchema LITE_SCHEMA = new ListFieldSchemaLite();
+
+  static ListFieldSchema full() {
+    return FULL_SCHEMA;
+  }
+
+  static ListFieldSchema lite() {
+    return LITE_SCHEMA;
+  }
+
+  private static ListFieldSchema loadSchemaForFullRuntime() {
+    try {
+      Class<?> clazz = Class.forName("com.google.protobuf.ListFieldSchemaFull");
+      return (ListFieldSchema) clazz.getDeclaredConstructor().newInstance();
+    } catch (Exception e) {
+      return null;
+    }
+  }
+
+  private ListFieldSchemas() {}
+}
diff --git a/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java b/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java
index c923b129db..9b4fd82d47 100644
--- a/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java
+++ b/java/core/src/main/java/com/google/protobuf/ManifestSchemaFactory.java
@@ -34,57 +34,37 @@ final class ManifestSchemaFactory implements SchemaFactory {
 
     // MessageSet has a special schema.
     if (messageInfo.isMessageSetWireFormat()) {
-      if (GeneratedMessageLite.class.isAssignableFrom(messageType)) {
-        return MessageSetSchema.newSchema(
-            SchemaUtil.unknownFieldSetLiteSchema(),
-            ExtensionSchemas.lite(),
-            messageInfo.getDefaultInstance());
-      }
-      return MessageSetSchema.newSchema(
-          SchemaUtil.unknownFieldSetFullSchema(),
-          ExtensionSchemas.full(),
-          messageInfo.getDefaultInstance());
+      return useLiteRuntime(messageType)
+          ? MessageSetSchema.newSchema(
+              SchemaUtil.unknownFieldSetLiteSchema(),
+              ExtensionSchemas.lite(),
+              messageInfo.getDefaultInstance())
+          : MessageSetSchema.newSchema(
+              SchemaUtil.unknownFieldSetFullSchema(),
+              ExtensionSchemas.full(),
+              messageInfo.getDefaultInstance());
     }
 
     return newSchema(messageType, messageInfo);
   }
 
   private static <T> Schema<T> newSchema(Class<T> messageType, MessageInfo messageInfo) {
-    if (GeneratedMessageLite.class.isAssignableFrom(messageType)) {
-      return allowExtensions(messageInfo)
-          ? MessageSchema.newSchema(
-              messageType,
-              messageInfo,
-              NewInstanceSchemas.lite(),
-              ListFieldSchema.lite(),
-              SchemaUtil.unknownFieldSetLiteSchema(),
-              ExtensionSchemas.lite(),
-              MapFieldSchemas.lite())
-          : MessageSchema.newSchema(
-              messageType,
-              messageInfo,
-              NewInstanceSchemas.lite(),
-              ListFieldSchema.lite(),
-              SchemaUtil.unknownFieldSetLiteSchema(),
-              /* extensionSchema= */ null,
-              MapFieldSchemas.lite());
-    }
-    return allowExtensions(messageInfo)
+    return useLiteRuntime(messageType)
         ? MessageSchema.newSchema(
             messageType,
             messageInfo,
-            NewInstanceSchemas.full(),
-            ListFieldSchema.full(),
-            SchemaUtil.unknownFieldSetFullSchema(),
-            ExtensionSchemas.full(),
-            MapFieldSchemas.full())
+            NewInstanceSchemas.lite(),
+            ListFieldSchemas.lite(),
+            SchemaUtil.unknownFieldSetLiteSchema(),
+            allowExtensions(messageInfo) ? ExtensionSchemas.lite() : null,
+            MapFieldSchemas.lite())
         : MessageSchema.newSchema(
             messageType,
             messageInfo,
             NewInstanceSchemas.full(),
-            ListFieldSchema.full(),
+            ListFieldSchemas.full(),
             SchemaUtil.unknownFieldSetFullSchema(),
-            /* extensionSchema= */ null,
+            allowExtensions(messageInfo) ? ExtensionSchemas.full() : null,
             MapFieldSchemas.full());
   }
 
@@ -152,4 +132,8 @@ final class ManifestSchemaFactory implements SchemaFactory {
       return EMPTY_FACTORY;
     }
   }
+
+  private static boolean useLiteRuntime(Class<?> messageType) {
+    return GeneratedMessageLite.class.isAssignableFrom(messageType);
+  }
 }
diff --git a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java
index d411449172..624c258d41 100644
--- a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java
+++ b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaFull.java
@@ -10,7 +10,7 @@ package com.google.protobuf;
 import com.google.protobuf.MapEntryLite.Metadata;
 import java.util.Map;
 
-class MapFieldSchemaFull implements MapFieldSchema {
+final class MapFieldSchemaFull implements MapFieldSchema {
   @Override
   public Map<?, ?> forMutableMapData(Object mapField) {
     return ((MapField<?, ?>) mapField).getMutableMap();
diff --git a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java
index f7c5d85f31..c21678d287 100644
--- a/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java
+++ b/java/core/src/main/java/com/google/protobuf/MapFieldSchemaLite.java
@@ -11,7 +11,7 @@ import com.google.protobuf.MapEntryLite.Metadata;
 import java.util.Map;
 
 @CheckReturnValue
-class MapFieldSchemaLite implements MapFieldSchema {
+final class MapFieldSchemaLite implements MapFieldSchema {
 
   @Override
   public Map<?, ?> forMutableMapData(Object mapField) {
diff --git a/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java b/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java
index d7eeccd8c4..ea419a56c6 100644
--- a/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java
+++ b/java/core/src/main/java/com/google/protobuf/MapFieldSchemas.java
@@ -28,4 +28,6 @@ final class MapFieldSchemas {
       return null;
     }
   }
+
+  private MapFieldSchemas() {}
 }
diff --git a/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java b/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java
index 800f44891c..6fbdd47a38 100644
--- a/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java
+++ b/java/core/src/main/java/com/google/protobuf/NewInstanceSchemas.java
@@ -28,4 +28,6 @@ final class NewInstanceSchemas {
       return null;
     }
   }
+
+  private NewInstanceSchemas() {}
 }
diff --git a/java/core/src/main/java/com/google/protobuf/RuntimeVersion.java b/java/core/src/main/java/com/google/protobuf/RuntimeVersion.java
index 3789a9db7b..5a51706417 100644
--- a/java/core/src/main/java/com/google/protobuf/RuntimeVersion.java
+++ b/java/core/src/main/java/com/google/protobuf/RuntimeVersion.java
@@ -24,12 +24,18 @@ public final class RuntimeVersion {
 
   // The version of this runtime.
   // Automatically updated by Protobuf release process. Do not edit manually.
-
-  public static final RuntimeDomain DOMAIN = RuntimeDomain.PUBLIC;
-  public static final int MAJOR = 4;
-  public static final int MINOR = 28;
-  public static final int PATCH = 0;
-  public static final String SUFFIX = "-dev";
+  // These OSS versions are not stripped to avoid merging conflicts.
+  public static final RuntimeDomain OSS_DOMAIN = RuntimeDomain.PUBLIC;
+  public static final int OSS_MAJOR = 4;
+  public static final int OSS_MINOR = 28;
+  public static final int OSS_PATCH = 0;
+  public static final String OSS_SUFFIX = "-dev";
+
+  public static final RuntimeDomain DOMAIN = OSS_DOMAIN;
+  public static final int MAJOR = OSS_MAJOR;
+  public static final int MINOR = OSS_MINOR;
+  public static final int PATCH = OSS_PATCH;
+  public static final String SUFFIX = OSS_SUFFIX;
 
   private static final String VERSION_STRING = versionString(MAJOR, MINOR, PATCH, SUFFIX);
   private static final Logger logger = Logger.getLogger(RuntimeVersion.class.getName());
@@ -88,7 +94,7 @@ public final class RuntimeVersion {
     }
 
     // Check that runtime version is newer than the gencode version.
-    if (MINOR < minor || (MINOR == minor && PATCH < patch)) {
+    if (MINOR < minor || (minor == MINOR && PATCH < patch)) {
       throw new ProtobufRuntimeVersionException(
           String.format(
               "Detected incompatible Protobuf Gencode/Runtime versions when loading %s: gencode %s,"
diff --git a/java/core/src/main/java/com/google/protobuf/SmallSortedMap.java b/java/core/src/main/java/com/google/protobuf/SmallSortedMap.java
index 17e8d77dba..55934d2187 100644
--- a/java/core/src/main/java/com/google/protobuf/SmallSortedMap.java
+++ b/java/core/src/main/java/com/google/protobuf/SmallSortedMap.java
@@ -14,7 +14,6 @@ import java.util.Collections;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
-import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.SortedMap;
 import java.util.TreeMap;
@@ -169,13 +168,13 @@ class SmallSortedMap<K extends Comparable<K>, V> extends AbstractMap<K, V> {
   /** @return An iterable over the overflow entries. */
   public Iterable<Map.Entry<K, V>> getOverflowEntries() {
     return overflowEntries.isEmpty()
-        ? EmptySet.<Map.Entry<K, V>>iterable()
+        ? Collections.emptySet()
         : overflowEntries.entrySet();
   }
 
   Iterable<Map.Entry<K, V>> getOverflowEntriesDescending() {
     return overflowEntriesDescending.isEmpty()
-        ? EmptySet.<Map.Entry<K, V>>iterable()
+        ? Collections.emptySet()
         : overflowEntriesDescending.entrySet();
   }
 
@@ -597,45 +596,6 @@ class SmallSortedMap<K extends Comparable<K>, V> extends AbstractMap<K, V> {
     }
   }
 
-  /**
-   * Helper class that holds immutable instances of an Iterable/Iterator that we return when the
-   * overflow entries is empty. This eliminates the creation of an Iterator object when there is
-   * nothing to iterate over.
-   */
-  private static class EmptySet {
-
-    private static final Iterator<Object> ITERATOR =
-        new Iterator<Object>() {
-          @Override
-          public boolean hasNext() {
-            return false;
-          }
-
-          @Override
-          public Object next() {
-            throw new NoSuchElementException();
-          }
-
-          @Override
-          public void remove() {
-            throw new UnsupportedOperationException();
-          }
-        };
-
-    private static final Iterable<Object> ITERABLE =
-        new Iterable<Object>() {
-          @Override
-          public Iterator<Object> iterator() {
-            return ITERATOR;
-          }
-        };
-
-    @SuppressWarnings("unchecked")
-    static <T> Iterable<T> iterable() {
-      return (Iterable<T>) ITERABLE;
-    }
-  }
-
   @Override
   public boolean equals(Object o) {
     if (this == o) {
diff --git a/java/core/src/main/java/com/google/protobuf/TextFormat.java b/java/core/src/main/java/com/google/protobuf/TextFormat.java
index eb05fb2f41..bb1237795d 100644
--- a/java/core/src/main/java/com/google/protobuf/TextFormat.java
+++ b/java/core/src/main/java/com/google/protobuf/TextFormat.java
@@ -38,6 +38,8 @@ public final class TextFormat {
 
   private static final String DEBUG_STRING_SILENT_MARKER = "\t ";
 
+  private static final String REDACTED_MARKER = "[REDACTED]";
+
   /**
    * Generates a human readable form of this message, useful for debugging and other purposes, with
    * no newline characters. This is just a trivial wrapper around {@link
@@ -58,11 +60,12 @@ public final class TextFormat {
    */
   public static void printUnknownFieldValue(
       final int tag, final Object value, final Appendable output) throws IOException {
-    printUnknownFieldValue(tag, value, multiLineOutput(output));
+    printUnknownFieldValue(tag, value, setSingleLineOutput(output, false), false);
   }
 
   private static void printUnknownFieldValue(
-      final int tag, final Object value, final TextGenerator generator) throws IOException {
+      final int tag, final Object value, final TextGenerator generator, boolean redact)
+      throws IOException {
     switch (WireFormat.getTagWireType(tag)) {
       case WireFormat.WIRETYPE_VARINT:
         generator.print(unsignedToString((Long) value));
@@ -80,7 +83,7 @@ public final class TextFormat {
           generator.print("{");
           generator.eol();
           generator.indent();
-          Printer.printUnknownFields(message, generator);
+          Printer.printUnknownFields(message, generator, redact);
           generator.outdent();
           generator.print("}");
         } catch (InvalidProtocolBufferException e) {
@@ -91,7 +94,7 @@ public final class TextFormat {
         }
         break;
       case WireFormat.WIRETYPE_START_GROUP:
-        Printer.printUnknownFields((UnknownFieldSet) value, generator);
+        Printer.printUnknownFields((UnknownFieldSet) value, generator, redact);
         break;
       default:
         throw new IllegalArgumentException("Bad tag: " + tag);
@@ -109,7 +112,11 @@ public final class TextFormat {
     // Printer instance which escapes non-ASCII characters.
     private static final Printer DEFAULT =
         new Printer(
-            true, TypeRegistry.getEmptyTypeRegistry(), ExtensionRegistryLite.getEmptyRegistry());
+            true,
+            TypeRegistry.getEmptyTypeRegistry(),
+            ExtensionRegistryLite.getEmptyRegistry(),
+            false,
+            false);
 
     /** Whether to escape non ASCII characters with backslash and octal. */
     private final boolean escapeNonAscii;
@@ -117,13 +124,25 @@ public final class TextFormat {
     private final TypeRegistry typeRegistry;
     private final ExtensionRegistryLite extensionRegistry;
 
+    /**
+     * Whether to enable redaction of sensitive fields and introduce randomization. Note that when
+     * this is enabled, the output will no longer be deserializable.
+     */
+    private final boolean enablingSafeDebugFormat;
+
+    private final boolean singleLine;
+
     private Printer(
         boolean escapeNonAscii,
         TypeRegistry typeRegistry,
-        ExtensionRegistryLite extensionRegistry) {
+        ExtensionRegistryLite extensionRegistry,
+        boolean enablingSafeDebugFormat,
+        boolean singleLine) {
       this.escapeNonAscii = escapeNonAscii;
       this.typeRegistry = typeRegistry;
       this.extensionRegistry = extensionRegistry;
+      this.enablingSafeDebugFormat = enablingSafeDebugFormat;
+      this.singleLine = singleLine;
     }
 
     /**
@@ -136,7 +155,8 @@ public final class TextFormat {
      *     with the escape mode set to the given parameter.
      */
     public Printer escapingNonAscii(boolean escapeNonAscii) {
-      return new Printer(escapeNonAscii, typeRegistry, extensionRegistry);
+      return new Printer(
+          escapeNonAscii, typeRegistry, extensionRegistry, enablingSafeDebugFormat, singleLine);
     }
 
     /**
@@ -149,7 +169,8 @@ public final class TextFormat {
       if (this.typeRegistry != TypeRegistry.getEmptyTypeRegistry()) {
         throw new IllegalArgumentException("Only one typeRegistry is allowed.");
       }
-      return new Printer(escapeNonAscii, typeRegistry, extensionRegistry);
+      return new Printer(
+          escapeNonAscii, typeRegistry, extensionRegistry, enablingSafeDebugFormat, singleLine);
     }
 
     /**
@@ -162,7 +183,34 @@ public final class TextFormat {
       if (this.extensionRegistry != ExtensionRegistryLite.getEmptyRegistry()) {
         throw new IllegalArgumentException("Only one extensionRegistry is allowed.");
       }
-      return new Printer(escapeNonAscii, typeRegistry, extensionRegistry);
+      return new Printer(
+          escapeNonAscii, typeRegistry, extensionRegistry, enablingSafeDebugFormat, singleLine);
+    }
+
+    /**
+     * Return a new Printer instance that outputs a redacted and unstable format suitable for
+     * debugging.
+     *
+     * @param enablingSafeDebugFormat If true, the new Printer will redact all proto fields that are
+     *     marked by a debug_redact=true option, and apply an unstable prefix to the output.
+     * @return a new Printer that clones all other configurations from the current {@link Printer},
+     *     with the enablingSafeDebugFormat mode set to the given parameter.
+     */
+    Printer enablingSafeDebugFormat(boolean enablingSafeDebugFormat) {
+      return new Printer(
+          escapeNonAscii, typeRegistry, extensionRegistry, enablingSafeDebugFormat, singleLine);
+    }
+
+    /**
+     * Return a new Printer instance with the specified line formatting status.
+     *
+     * @param singleLine If true, the new Printer will output no newline characters.
+     * @return a new Printer that clones all other configurations from the current {@link Printer},
+     *     with the singleLine mode set to the given parameter.
+     */
+    public Printer emittingSingleLine(boolean singleLine) {
+      return new Printer(
+          escapeNonAscii, typeRegistry, extensionRegistry, enablingSafeDebugFormat, singleLine);
     }
 
     /**
@@ -171,12 +219,13 @@ public final class TextFormat {
      * original Protocol Buffer system)
      */
     public void print(final MessageOrBuilder message, final Appendable output) throws IOException {
-      print(message, multiLineOutput(output));
+      print(message, setSingleLineOutput(output, this.singleLine));
     }
 
     /** Outputs a textual representation of {@code fields} to {@code output}. */
     public void print(final UnknownFieldSet fields, final Appendable output) throws IOException {
-      printUnknownFields(fields, multiLineOutput(output));
+      printUnknownFields(
+          fields, setSingleLineOutput(output, this.singleLine), this.enablingSafeDebugFormat);
     }
 
     private void print(final MessageOrBuilder message, final TextGenerator generator)
@@ -188,6 +237,14 @@ public final class TextFormat {
       printMessage(message, generator);
     }
 
+    private void applyUnstablePrefix(final Appendable output) {
+      try {
+        output.append("");
+      } catch (IOException e) {
+        throw new IllegalStateException(e);
+      }
+    }
+
     /**
      * Attempt to print the 'google.protobuf.Any' message in a human-friendly format. Returns false
      * if the message isn't a valid 'google.protobuf.Any' message (in which case the message should
@@ -244,6 +301,9 @@ public final class TextFormat {
     public String printFieldToString(final FieldDescriptor field, final Object value) {
       try {
         final StringBuilder text = new StringBuilder();
+        if (enablingSafeDebugFormat) {
+          applyUnstablePrefix(text);
+        }
         printField(field, value, text);
         return text.toString();
       } catch (IOException e) {
@@ -253,7 +313,7 @@ public final class TextFormat {
 
     public void printField(final FieldDescriptor field, final Object value, final Appendable output)
         throws IOException {
-      printField(field, value, multiLineOutput(output));
+      printField(field, value, setSingleLineOutput(output, this.singleLine));
     }
 
     private void printField(
@@ -358,12 +418,19 @@ public final class TextFormat {
     public void printFieldValue(
         final FieldDescriptor field, final Object value, final Appendable output)
         throws IOException {
-      printFieldValue(field, value, multiLineOutput(output));
+      printFieldValue(field, value, setSingleLineOutput(output, this.singleLine));
     }
 
     private void printFieldValue(
         final FieldDescriptor field, final Object value, final TextGenerator generator)
         throws IOException {
+      if (shouldRedact(field)) {
+        generator.print(REDACTED_MARKER);
+        if (field.getJavaType() == FieldDescriptor.JavaType.MESSAGE) {
+          generator.eol();
+        }
+        return;
+      }
       switch (field.getType()) {
         case INT32:
         case SINT32:
@@ -429,10 +496,54 @@ public final class TextFormat {
       }
     }
 
+    private boolean shouldRedactOptionValue(EnumValueDescriptor optionValue) {
+      if (optionValue.getOptions().hasDebugRedact()) {
+        return optionValue.getOptions().getDebugRedact();
+      }
+      return false;
+    }
+
+    // The criteria for redacting a field is as follows: 1) The enablingSafeDebugFormat printer
+    // option
+    // must be on. 2) The field must be marked by a debug_redact=true option, or is marked by an
+    // option with an enum value that is marked by a debug_redact=true option.
+    private boolean shouldRedact(final FieldDescriptor field) {
+      if (!this.enablingSafeDebugFormat) {
+        return false;
+      }
+      if (field.getOptions().hasDebugRedact()) {
+        return field.getOptions().getDebugRedact();
+      }
+      // Iterate through every option; if it's an enum, we check each enum value for debug_redact.
+      for (Map.Entry<Descriptors.FieldDescriptor, Object> entry :
+          field.getOptions().getAllFields().entrySet()) {
+        Descriptors.FieldDescriptor option = entry.getKey();
+        if (option.getType() != Descriptors.FieldDescriptor.Type.ENUM) {
+          continue;
+        }
+        if (option.isRepeated()) {
+          for (EnumValueDescriptor value : (List<EnumValueDescriptor>) entry.getValue()) {
+            if (shouldRedactOptionValue(value)) {
+              return true;
+            }
+          }
+        } else {
+          EnumValueDescriptor optionValue = (EnumValueDescriptor) entry.getValue();
+          if (shouldRedactOptionValue(optionValue)) {
+            return true;
+          }
+        }
+      }
+      return false;
+    }
+
     /** Like {@code print()}, but writes directly to a {@code String} and returns it. */
     public String printToString(final MessageOrBuilder message) {
       try {
         final StringBuilder text = new StringBuilder();
+        if (enablingSafeDebugFormat) {
+          applyUnstablePrefix(text);
+        }
         print(message, text);
         return text.toString();
       } catch (IOException e) {
@@ -443,6 +554,9 @@ public final class TextFormat {
     public String printToString(final UnknownFieldSet fields) {
       try {
         final StringBuilder text = new StringBuilder();
+        if (enablingSafeDebugFormat) {
+          applyUnstablePrefix(text);
+        }
         print(fields, text);
         return text.toString();
       } catch (IOException e) {
@@ -457,7 +571,7 @@ public final class TextFormat {
     public String shortDebugString(final MessageOrBuilder message) {
       try {
         final StringBuilder text = new StringBuilder();
-        print(message, singleLineOutput(text));
+        print(message, setSingleLineOutput(text, true));
         return text.toString();
       } catch (IOException e) {
         throw new IllegalStateException(e);
@@ -471,7 +585,7 @@ public final class TextFormat {
     public String shortDebugString(final FieldDescriptor field, final Object value) {
       try {
         final StringBuilder text = new StringBuilder();
-        printField(field, value, singleLineOutput(text));
+        printField(field, value, setSingleLineOutput(text, true));
         return text.toString();
       } catch (IOException e) {
         throw new IllegalStateException(e);
@@ -485,7 +599,7 @@ public final class TextFormat {
     public String shortDebugString(final UnknownFieldSet fields) {
       try {
         final StringBuilder text = new StringBuilder();
-        printUnknownFields(fields, singleLineOutput(text));
+        printUnknownFields(fields, setSingleLineOutput(text, true), this.enablingSafeDebugFormat);
         return text.toString();
       } catch (IOException e) {
         throw new IllegalStateException(e);
@@ -493,16 +607,26 @@ public final class TextFormat {
     }
 
     private static void printUnknownFieldValue(
-        final int tag, final Object value, final TextGenerator generator) throws IOException {
+        final int tag, final Object value, final TextGenerator generator, boolean redact)
+        throws IOException {
       switch (WireFormat.getTagWireType(tag)) {
         case WireFormat.WIRETYPE_VARINT:
-          generator.print(unsignedToString((Long) value));
+          generator.print(
+              redact
+                  ? String.format("UNKNOWN_VARINT %s", REDACTED_MARKER)
+                  : unsignedToString((Long) value));
           break;
         case WireFormat.WIRETYPE_FIXED32:
-          generator.print(String.format((Locale) null, "0x%08x", (Integer) value));
+          generator.print(
+              redact
+                  ? String.format("UNKNOWN_FIXED32 %s", REDACTED_MARKER)
+                  : String.format((Locale) null, "0x%08x", (Integer) value));
           break;
         case WireFormat.WIRETYPE_FIXED64:
-          generator.print(String.format((Locale) null, "0x%016x", (Long) value));
+          generator.print(
+              redact
+                  ? String.format("UNKNOWN_FIXED64 %s", REDACTED_MARKER)
+                  : String.format((Locale) null, "0x%016x", (Long) value));
           break;
         case WireFormat.WIRETYPE_LENGTH_DELIMITED:
           try {
@@ -511,18 +635,22 @@ public final class TextFormat {
             generator.print("{");
             generator.eol();
             generator.indent();
-            printUnknownFields(message, generator);
+            printUnknownFields(message, generator, redact);
             generator.outdent();
             generator.print("}");
           } catch (InvalidProtocolBufferException e) {
             // If not parseable as a message, print as a String
+            if (redact) {
+              generator.print(String.format("UNKNOWN_STRING %s", REDACTED_MARKER));
+              break;
+            }
             generator.print("\"");
             generator.print(escapeBytes((ByteString) value));
             generator.print("\"");
           }
           break;
         case WireFormat.WIRETYPE_START_GROUP:
-          printUnknownFields((UnknownFieldSet) value, generator);
+          printUnknownFields((UnknownFieldSet) value, generator, redact);
           break;
         default:
           throw new IllegalArgumentException("Bad tag: " + tag);
@@ -534,7 +662,7 @@ public final class TextFormat {
       for (Map.Entry<FieldDescriptor, Object> field : message.getAllFields().entrySet()) {
         printField(field.getKey(), field.getValue(), generator);
       }
-      printUnknownFields(message.getUnknownFields(), generator);
+      printUnknownFields(message.getUnknownFields(), generator, this.enablingSafeDebugFormat);
     }
 
     private void printSingleField(
@@ -580,24 +708,32 @@ public final class TextFormat {
     }
 
     private static void printUnknownFields(
-        final UnknownFieldSet unknownFields, final TextGenerator generator) throws IOException {
+        final UnknownFieldSet unknownFields, final TextGenerator generator, boolean redact)
+        throws IOException {
+      if (unknownFields.isEmpty()) {
+        return;
+      }
       for (Map.Entry<Integer, UnknownFieldSet.Field> entry : unknownFields.asMap().entrySet()) {
         final int number = entry.getKey();
         final UnknownFieldSet.Field field = entry.getValue();
-        printUnknownField(number, WireFormat.WIRETYPE_VARINT, field.getVarintList(), generator);
-        printUnknownField(number, WireFormat.WIRETYPE_FIXED32, field.getFixed32List(), generator);
-        printUnknownField(number, WireFormat.WIRETYPE_FIXED64, field.getFixed64List(), generator);
+        printUnknownField(
+            number, WireFormat.WIRETYPE_VARINT, field.getVarintList(), generator, redact);
+        printUnknownField(
+            number, WireFormat.WIRETYPE_FIXED32, field.getFixed32List(), generator, redact);
+        printUnknownField(
+            number, WireFormat.WIRETYPE_FIXED64, field.getFixed64List(), generator, redact);
         printUnknownField(
             number,
             WireFormat.WIRETYPE_LENGTH_DELIMITED,
             field.getLengthDelimitedList(),
-            generator);
+            generator,
+            redact);
         for (final UnknownFieldSet value : field.getGroupList()) {
           generator.print(entry.getKey().toString());
           generator.print(" {");
           generator.eol();
           generator.indent();
-          printUnknownFields(value, generator);
+          printUnknownFields(value, generator, redact);
           generator.outdent();
           generator.print("}");
           generator.eol();
@@ -606,12 +742,16 @@ public final class TextFormat {
     }
 
     private static void printUnknownField(
-        final int number, final int wireType, final List<?> values, final TextGenerator generator)
+        final int number,
+        final int wireType,
+        final List<?> values,
+        final TextGenerator generator,
+        boolean redact)
         throws IOException {
       for (final Object value : values) {
         generator.print(String.valueOf(number));
         generator.print(": ");
-        printUnknownFieldValue(wireType, value, generator);
+        printUnknownFieldValue(wireType, value, generator, redact);
         generator.eol();
       }
     }
@@ -637,12 +777,8 @@ public final class TextFormat {
     }
   }
 
-  private static TextGenerator multiLineOutput(Appendable output) {
-    return new TextGenerator(output, false);
-  }
-
-  private static TextGenerator singleLineOutput(Appendable output) {
-    return new TextGenerator(output, true);
+  private static TextGenerator setSingleLineOutput(Appendable output, boolean singleLine) {
+    return new TextGenerator(output, singleLine);
   }
 
   /** An inner class for writing text to the output stream. */
diff --git a/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java b/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
index 10fd7a7f62..2c21c54794 100644
--- a/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
+++ b/java/core/src/main/java/com/google/protobuf/UnknownFieldSet.java
@@ -83,8 +83,17 @@ public final class UnknownFieldSet implements MessageLite {
     return fields.hashCode();
   }
 
+  /** Whether the field set has no fields. */
+  public boolean isEmpty() {
+    return fields.isEmpty();
+  }
+
   /** Get a map of fields in the set by number. */
   public Map<Integer, Field> asMap() {
+    // Avoid an allocation for the common case of an empty map.
+    if (fields.isEmpty()) {
+      return Collections.emptyMap();
+    }
     return (Map<Integer, Field>) fields.clone();
   }
 
@@ -102,6 +111,10 @@ public final class UnknownFieldSet implements MessageLite {
   /** Serializes the set and writes it to {@code output}. */
   @Override
   public void writeTo(CodedOutputStream output) throws IOException {
+    if (fields.isEmpty()) {
+      // Avoid allocating an iterator.
+      return;
+    }
     for (Map.Entry<Integer, Field> entry : fields.entrySet()) {
       Field field = entry.getValue();
       field.writeTo(entry.getKey(), output);
@@ -174,16 +187,22 @@ public final class UnknownFieldSet implements MessageLite {
   @Override
   public int getSerializedSize() {
     int result = 0;
-    if (!fields.isEmpty()) {
-      for (Map.Entry<Integer, Field> entry : fields.entrySet()) {
-        result += entry.getValue().getSerializedSize(entry.getKey());
-      }
+    if (fields.isEmpty()) {
+      // Avoid allocating an iterator.
+      return result;
+    }
+    for (Map.Entry<Integer, Field> entry : fields.entrySet()) {
+      result += entry.getValue().getSerializedSize(entry.getKey());
     }
     return result;
   }
 
   /** Serializes the set and writes it to {@code output} using {@code MessageSet} wire format. */
   public void writeAsMessageSetTo(CodedOutputStream output) throws IOException {
+    if (fields.isEmpty()) {
+      // Avoid allocating an iterator.
+      return;
+    }
     for (Map.Entry<Integer, Field> entry : fields.entrySet()) {
       entry.getValue().writeAsMessageSetExtensionTo(entry.getKey(), output);
     }
@@ -191,6 +210,10 @@ public final class UnknownFieldSet implements MessageLite {
 
   /** Serializes the set and writes it to {@code writer}. */
   void writeTo(Writer writer) throws IOException {
+    if (fields.isEmpty()) {
+      // Avoid allocating an iterator.
+      return;
+    }
     if (writer.fieldOrder() == Writer.FieldOrder.DESCENDING) {
       // Write fields in descending order.
       for (Map.Entry<Integer, Field> entry : fields.descendingMap().entrySet()) {
@@ -206,6 +229,10 @@ public final class UnknownFieldSet implements MessageLite {
 
   /** Serializes the set and writes it to {@code writer} using {@code MessageSet} wire format. */
   void writeAsMessageSetTo(Writer writer) throws IOException {
+    if (fields.isEmpty()) {
+      // Avoid allocating an iterator.
+      return;
+    }
     if (writer.fieldOrder() == Writer.FieldOrder.DESCENDING) {
       // Write fields in descending order.
       for (Map.Entry<Integer, Field> entry : fields.descendingMap().entrySet()) {
@@ -222,6 +249,10 @@ public final class UnknownFieldSet implements MessageLite {
   /** Get the number of bytes required to encode this set using {@code MessageSet} wire format. */
   public int getSerializedSizeAsMessageSet() {
     int result = 0;
+    if (fields.isEmpty()) {
+      // Avoid allocating an iterator.
+      return result;
+    }
     for (Map.Entry<Integer, Field> entry : fields.entrySet()) {
       result += entry.getValue().getSerializedSizeAsMessageSetExtension(entry.getKey());
     }
@@ -452,6 +483,11 @@ public final class UnknownFieldSet implements MessageLite {
      * changes may or may not be reflected in this map.
      */
     public Map<Integer, Field> asMap() {
+      // Avoid an allocation for the common case of an empty map.
+      if (fieldBuilders.isEmpty()) {
+        return Collections.emptyMap();
+      }
+
       TreeMap<Integer, Field> fields = new TreeMap<>();
       for (Map.Entry<Integer, Field.Builder> entry : fieldBuilders.entrySet()) {
         fields.put(entry.getKey(), entry.getValue().build());
diff --git a/java/core/src/test/java/com/google/protobuf/DebugFormatTest.java b/java/core/src/test/java/com/google/protobuf/DebugFormatTest.java
new file mode 100644
index 0000000000..daf2924d98
--- /dev/null
+++ b/java/core/src/test/java/com/google/protobuf/DebugFormatTest.java
@@ -0,0 +1,210 @@
+package com.google.protobuf;
+
+import static com.google.common.truth.Truth.assertThat;
+import static protobuf_unittest.UnittestProto.redactedExtension;
+
+import com.google.protobuf.Descriptors.FieldDescriptor;
+import protobuf_unittest.UnittestProto.RedactedFields;
+import protobuf_unittest.UnittestProto.TestEmptyMessage;
+import protobuf_unittest.UnittestProto.TestNestedMessageRedaction;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public final class DebugFormatTest {
+
+  private static final String REDACTED_REGEX = "\\[REDACTED\\]";
+  private static final String UNSTABLE_PREFIX_SINGLE_LINE = getUnstablePrefix(true);
+  private static final String UNSTABLE_PREFIX_MULTILINE = getUnstablePrefix(false);
+
+  private static String getUnstablePrefix(boolean singleLine) {
+    return "";
+  }
+
+  @Test
+  public void multilineMessageFormat_returnsMultiline() {
+    RedactedFields message = RedactedFields.newBuilder().setOptionalUnredactedString("foo").build();
+
+    String result = DebugFormat.multiline().toString(message);
+    assertThat(result)
+        .matches(
+            String.format("%soptional_unredacted_string: \"foo\"\n", UNSTABLE_PREFIX_MULTILINE));
+  }
+
+  @Test
+  public void singleLineMessageFormat_returnsSingleLine() {
+    RedactedFields message = RedactedFields.newBuilder().setOptionalUnredactedString("foo").build();
+
+    String result = DebugFormat.singleLine().toString(message);
+    assertThat(result)
+        .matches(
+            String.format("%soptional_unredacted_string: \"foo\"", UNSTABLE_PREFIX_SINGLE_LINE));
+  }
+
+  @Test
+  public void messageFormat_debugRedactFieldIsRedacted() {
+    RedactedFields message = RedactedFields.newBuilder().setOptionalRedactedString("foo").build();
+
+    String result = DebugFormat.multiline().toString(message);
+
+    assertThat(result)
+        .matches(
+            String.format(
+                "%soptional_redacted_string: %s\n", UNSTABLE_PREFIX_MULTILINE, REDACTED_REGEX));
+  }
+
+  @Test
+  public void messageFormat_debugRedactMessageIsRedacted() {
+    RedactedFields message =
+        RedactedFields.newBuilder()
+            .setOptionalRedactedMessage(
+                TestNestedMessageRedaction.newBuilder().setOptionalUnredactedNestedString("foo"))
+            .build();
+
+    String result = DebugFormat.multiline().toString(message);
+
+    assertThat(result)
+        .matches(
+            String.format(
+                "%soptional_redacted_message \\{\n  %s\n\\}\n",
+                UNSTABLE_PREFIX_MULTILINE, REDACTED_REGEX));
+  }
+
+  @Test
+  public void messageFormat_debugRedactMapIsRedacted() {
+    RedactedFields message = RedactedFields.newBuilder().putMapRedactedString("foo", "bar").build();
+
+    String result = DebugFormat.multiline().toString(message);
+
+    assertThat(result)
+        .matches(
+            String.format(
+                "%smap_redacted_string \\{\\n  %s\n\\}\n",
+                UNSTABLE_PREFIX_MULTILINE, REDACTED_REGEX));
+  }
+
+  @Test
+  public void messageFormat_debugRedactExtensionIsRedacted() {
+    RedactedFields message =
+        RedactedFields.newBuilder().setExtension(redactedExtension, "foo").build();
+
+    String result = DebugFormat.multiline().toString(message);
+
+    assertThat(result)
+        .matches(
+            String.format(
+                "%s\\[protobuf_unittest\\.redacted_extension\\]: %s\n",
+                UNSTABLE_PREFIX_MULTILINE, REDACTED_REGEX));
+  }
+
+  @Test
+  public void messageFormat_redactFalseIsNotRedacted() {
+    RedactedFields message =
+        RedactedFields.newBuilder().setOptionalRedactedFalseString("foo").build();
+
+    String result = DebugFormat.multiline().toString(message);
+    assertThat(result)
+        .matches(
+            String.format(
+                "%soptional_redacted_false_string: \"foo\"\n", UNSTABLE_PREFIX_MULTILINE));
+  }
+
+  @Test
+  public void messageFormat_nonSensitiveFieldIsNotRedacted() {
+    RedactedFields message = RedactedFields.newBuilder().setOptionalUnredactedString("foo").build();
+
+    String result = DebugFormat.multiline().toString(message);
+
+    assertThat(result)
+        .matches(
+            String.format("%soptional_unredacted_string: \"foo\"\n", UNSTABLE_PREFIX_MULTILINE));
+  }
+
+  @Test
+  public void descriptorDebugFormat_returnsExpectedFormat() {
+    FieldDescriptor field =
+        RedactedFields.getDescriptor().findFieldByName("optional_redacted_string");
+    String result = DebugFormat.multiline().toString(field, "foo");
+    assertThat(result)
+        .matches(
+            String.format(
+                "%soptional_redacted_string: %s\n", UNSTABLE_PREFIX_MULTILINE, REDACTED_REGEX));
+  }
+
+  @Test
+  public void unstableFormat_isStablePerProcess() {
+    RedactedFields message1 =
+        RedactedFields.newBuilder().setOptionalUnredactedString("foo").build();
+    RedactedFields message2 =
+        RedactedFields.newBuilder().setOptionalUnredactedString("foo").build();
+    for (int i = 0; i < 5; i++) {
+      String result1 = DebugFormat.multiline().toString(message1);
+      String result2 = DebugFormat.multiline().toString(message2);
+      assertThat(result1).isEqualTo(result2);
+    }
+  }
+
+  @Test
+  public void lazyDebugFormatMessage_supportsImplicitFormatting() {
+    RedactedFields message = RedactedFields.newBuilder().setOptionalUnredactedString("foo").build();
+
+    Object lazyDebug = DebugFormat.singleLine().lazyToString(message);
+
+    assertThat(String.format("%s", lazyDebug))
+        .matches(
+            String.format("%soptional_unredacted_string: \"foo\"", UNSTABLE_PREFIX_SINGLE_LINE));
+  }
+
+  private UnknownFieldSet makeUnknownFieldSet() {
+    return UnknownFieldSet.newBuilder()
+        .addField(
+            5,
+            UnknownFieldSet.Field.newBuilder()
+                .addVarint(1)
+                .addFixed32(2)
+                .addFixed64(3)
+                .addLengthDelimited(ByteString.copyFromUtf8("4"))
+                .addLengthDelimited(
+                    UnknownFieldSet.newBuilder()
+                        .addField(12, UnknownFieldSet.Field.newBuilder().addVarint(6).build())
+                        .build()
+                        .toByteString())
+                .addGroup(
+                    UnknownFieldSet.newBuilder()
+                        .addField(10, UnknownFieldSet.Field.newBuilder().addVarint(5).build())
+                        .build())
+                .build())
+        .addField(
+            8, UnknownFieldSet.Field.newBuilder().addVarint(1).addVarint(2).addVarint(3).build())
+        .addField(
+            15,
+            UnknownFieldSet.Field.newBuilder()
+                .addVarint(0xABCDEF1234567890L)
+                .addFixed32(0xABCD1234)
+                .addFixed64(0xABCDEF1234567890L)
+                .build())
+        .build();
+  }
+
+  @Test
+  public void unknownFieldsDebugFormat_returnsExpectedFormat() {
+    TestEmptyMessage unknownFields =
+        TestEmptyMessage.newBuilder().setUnknownFields(makeUnknownFieldSet()).build();
+
+    assertThat(DebugFormat.multiline().toString(unknownFields))
+        .matches(
+            String.format("%s5: UNKNOWN_VARINT %s\n", UNSTABLE_PREFIX_MULTILINE, REDACTED_REGEX)
+                + String.format("5: UNKNOWN_FIXED32 %s\n", REDACTED_REGEX)
+                + String.format("5: UNKNOWN_FIXED64 %s\n", REDACTED_REGEX)
+                + String.format("5: UNKNOWN_STRING %s\n", REDACTED_REGEX)
+                + String.format("5: \\{\n  12: UNKNOWN_VARINT %s\n\\}\n", REDACTED_REGEX)
+                + String.format("5 \\{\n  10: UNKNOWN_VARINT %s\n\\}\n", REDACTED_REGEX)
+                + String.format("8: UNKNOWN_VARINT %s\n", REDACTED_REGEX)
+                + String.format("8: UNKNOWN_VARINT %s\n", REDACTED_REGEX)
+                + String.format("8: UNKNOWN_VARINT %s\n", REDACTED_REGEX)
+                + String.format("15: UNKNOWN_VARINT %s\n", REDACTED_REGEX)
+                + String.format("15: UNKNOWN_FIXED32 %s\n", REDACTED_REGEX)
+                + String.format("15: UNKNOWN_FIXED64 %s\n", REDACTED_REGEX));
+  }
+}
diff --git a/java/core/src/test/java/com/google/protobuf/DescriptorsTest.java b/java/core/src/test/java/com/google/protobuf/DescriptorsTest.java
index d64186ad7a..2ebdf71e75 100644
--- a/java/core/src/test/java/com/google/protobuf/DescriptorsTest.java
+++ b/java/core/src/test/java/com/google/protobuf/DescriptorsTest.java
@@ -1158,7 +1158,7 @@ public class DescriptorsTest {
                   .setOptions(FileOptions.newBuilder().setJavaStringCheckUtf8(true))
                   .build(),
               new FileDescriptor[0]);
-      assertThat(file.features.getExtension(JavaFeaturesProto.java).getUtf8Validation())
+      assertThat(file.features.getExtension(JavaFeaturesProto.java_).getUtf8Validation())
           .isEqualTo(JavaFeaturesProto.JavaFeatures.Utf8Validation.VERIFY);
     }
 
@@ -1178,8 +1178,8 @@ public class DescriptorsTest {
       assertThat(features.getJsonFormat())
           .isEqualTo(DescriptorProtos.FeatureSet.JsonFormat.LEGACY_BEST_EFFORT);
 
-      assertThat(features.getExtension(JavaFeaturesProto.java).getLegacyClosedEnum()).isTrue();
-      assertThat(features.getExtension(JavaFeaturesProto.java).getUtf8Validation())
+      assertThat(features.getExtension(JavaFeaturesProto.java_).getLegacyClosedEnum()).isTrue();
+      assertThat(features.getExtension(JavaFeaturesProto.java_).getUtf8Validation())
           .isEqualTo(JavaFeaturesProto.JavaFeatures.Utf8Validation.DEFAULT);
     }
 
@@ -1198,8 +1198,8 @@ public class DescriptorsTest {
       assertThat(features.getMessageEncoding())
           .isEqualTo(DescriptorProtos.FeatureSet.MessageEncoding.LENGTH_PREFIXED);
 
-      assertThat(features.getExtension(JavaFeaturesProto.java).getLegacyClosedEnum()).isFalse();
-      assertThat(features.getExtension(JavaFeaturesProto.java).getUtf8Validation())
+      assertThat(features.getExtension(JavaFeaturesProto.java_).getLegacyClosedEnum()).isFalse();
+      assertThat(features.getExtension(JavaFeaturesProto.java_).getUtf8Validation())
           .isEqualTo(JavaFeaturesProto.JavaFeatures.Utf8Validation.DEFAULT);
     }
 
diff --git a/java/core/src/test/proto/com/google/protobuf/test_check_utf8.proto b/java/core/src/test/proto/com/google/protobuf/test_check_utf8.proto
index 3af9831d29..fff2805e78 100644
--- a/java/core/src/test/proto/com/google/protobuf/test_check_utf8.proto
+++ b/java/core/src/test/proto/com/google/protobuf/test_check_utf8.proto
@@ -12,7 +12,10 @@ edition = "2023";
 
 package proto2_test_check_utf8;
 
-option features.utf8_validation = VERIFY;
+import "google/protobuf/java_features.proto";
+
+option features.utf8_validation = NONE;
+option features.(pb.java).utf8_validation = VERIFY;
 option java_outer_classname = "TestCheckUtf8";
 
 message StringWrapper {
diff --git a/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt b/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt
index c9fee8a78f..7c319bfaac 100644
--- a/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt
+++ b/java/kotlin/src/test/kotlin/com/google/protobuf/Proto2Test.kt
@@ -225,7 +225,7 @@ class Proto2Test {
             TestAllTypesKt.repeatedGroup { a = 1 },
             TestAllTypesKt.repeatedGroup { a = 2 },
             TestAllTypesKt.repeatedGroup { a = 3 },
-            TestAllTypesKt.repeatedGroup { a = 4 }
+            TestAllTypesKt.repeatedGroup { a = 4 },
           )
         )
       repeatedGroup[0] = TestAllTypesKt.repeatedGroup { a = 5 }
@@ -235,7 +235,7 @@ class Proto2Test {
             TestAllTypesKt.repeatedGroup { a = 5 },
             TestAllTypesKt.repeatedGroup { a = 2 },
             TestAllTypesKt.repeatedGroup { a = 3 },
-            TestAllTypesKt.repeatedGroup { a = 4 }
+            TestAllTypesKt.repeatedGroup { a = 4 },
           )
         )
 
@@ -249,7 +249,7 @@ class Proto2Test {
             nestedMessage { bb = 1 },
             nestedMessage { bb = 2 },
             nestedMessage { bb = 3 },
-            nestedMessage { bb = 4 }
+            nestedMessage { bb = 4 },
           )
         )
       repeatedNestedMessage[0] = nestedMessage { bb = 5 }
@@ -259,7 +259,7 @@ class Proto2Test {
             nestedMessage { bb = 5 },
             nestedMessage { bb = 2 },
             nestedMessage { bb = 3 },
-            nestedMessage { bb = 4 }
+            nestedMessage { bb = 4 },
           )
         )
 
@@ -548,7 +548,7 @@ class Proto2Test {
             repeatedGroupExtension { a = 1 },
             repeatedGroupExtension { a = 2 },
             repeatedGroupExtension { a = 3 },
-            repeatedGroupExtension { a = 4 }
+            repeatedGroupExtension { a = 4 },
           )
         )
       this[UnittestProto.repeatedGroupExtension][0] = repeatedGroupExtension { a = 5 }
@@ -558,7 +558,7 @@ class Proto2Test {
             repeatedGroupExtension { a = 5 },
             repeatedGroupExtension { a = 2 },
             repeatedGroupExtension { a = 3 },
-            repeatedGroupExtension { a = 4 }
+            repeatedGroupExtension { a = 4 },
           )
         )
 
@@ -575,7 +575,7 @@ class Proto2Test {
             nestedMessage { bb = 1 },
             nestedMessage { bb = 2 },
             nestedMessage { bb = 3 },
-            nestedMessage { bb = 4 }
+            nestedMessage { bb = 4 },
           )
         )
       this[UnittestProto.repeatedNestedMessageExtension][0] = nestedMessage { bb = 5 }
@@ -585,7 +585,7 @@ class Proto2Test {
             nestedMessage { bb = 5 },
             nestedMessage { bb = 2 },
             nestedMessage { bb = 3 },
-            nestedMessage { bb = 4 }
+            nestedMessage { bb = 4 },
           )
         )
 
@@ -757,7 +757,7 @@ class Proto2Test {
             1 to Proto2MapEnum.PROTO2_MAP_ENUM_FOO,
             2 to Proto2MapEnum.PROTO2_MAP_ENUM_BAR,
             3 to Proto2MapEnum.PROTO2_MAP_ENUM_BAZ,
-            4 to Proto2MapEnum.PROTO2_MAP_ENUM_FOO
+            4 to Proto2MapEnum.PROTO2_MAP_ENUM_FOO,
           )
         )
     }
@@ -844,6 +844,11 @@ class Proto2Test {
           cachedSize_ = "foo"
           serializedSize_ = true
           by = "foo"
+          dEPRECATEDFoo = "foo"
+          DEPRECATEDBar = "foo"
+          iD = "foo"
+          aBNotification = "foo"
+          notDEPRECATEDFoo = "foo"
         }
       )
       .isEqualTo(
@@ -869,6 +874,11 @@ class Proto2Test {
           .setCachedSize_("foo")
           .setSerializedSize_(true)
           .setBy("foo")
+          .setDEPRECATEDFoo("foo")
+          .setDEPRECATEDBar("foo")
+          .setID("foo")
+          .setABNotification("foo")
+          .setNotDEPRECATEDFoo("foo")
           .build()
       )
 
diff --git a/java/kotlin/src/test/kotlin/com/google/protobuf/Proto3Test.kt b/java/kotlin/src/test/kotlin/com/google/protobuf/Proto3Test.kt
index 0b270e6e75..72ab8e1f80 100644
--- a/java/kotlin/src/test/kotlin/com/google/protobuf/Proto3Test.kt
+++ b/java/kotlin/src/test/kotlin/com/google/protobuf/Proto3Test.kt
@@ -81,7 +81,7 @@ class Proto3Test {
             nestedMessage { bb = 1 },
             nestedMessage { bb = 2 },
             nestedMessage { bb = 3 },
-            nestedMessage { bb = 4 }
+            nestedMessage { bb = 4 },
           )
         )
       repeatedNestedMessage[0] = nestedMessage { bb = 5 }
@@ -91,7 +91,7 @@ class Proto3Test {
             nestedMessage { bb = 5 },
             nestedMessage { bb = 2 },
             nestedMessage { bb = 3 },
-            nestedMessage { bb = 4 }
+            nestedMessage { bb = 4 },
           )
         )
 
@@ -200,6 +200,11 @@ class Proto3Test {
           pairs["foo"] = 1
           LeadingUnderscore = "foo"
           option = 1
+          dEPRECATEDFoo = "foo"
+          iD = "foo"
+          aBNotification = "foo"
+          DEPRECATEDBar = "foo"
+          notDEPRECATEDFoo = "foo"
         }
       )
       .isEqualTo(
@@ -237,6 +242,11 @@ class Proto3Test {
           .putPairs("foo", 1)
           .setLeadingUnderscore("foo")
           .setOption(1)
+          .setDEPRECATEDFoo("foo")
+          .setID("foo")
+          .setABNotification("foo")
+          .setDEPRECATEDBar("foo")
+          .setNotDEPRECATEDFoo("foo")
           .build()
       )
 
diff --git a/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto2.proto b/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto2.proto
index ba0827422b..f771bf97bf 100644
--- a/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto2.proto
+++ b/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto2.proto
@@ -43,6 +43,15 @@ message EvilNamesProto2 {
   optional string cached_size = 23;
   optional bool serialized_size = 24;
   optional string by = 25;
+
+  optional string DEPRECATED_foo = 26;
+  optional group DEPRECATED_NavigationImageRequested = 27 {
+    optional int32 DEPRECATED_FooBar = 28;
+  }
+  optional string __DEPRECATED_Bar = 29;
+  optional string ID = 30;
+  optional string a_b_notification = 31;
+  optional string not_DEPRECATED_foo = 32;
 }
 
 message List {}
diff --git a/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto3.proto b/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto3.proto
index 2c9b5a2d68..238bebc06b 100644
--- a/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto3.proto
+++ b/java/kotlin/src/test/proto/com/google/protobuf/evil_names_proto3.proto
@@ -56,6 +56,12 @@ message EvilNamesProto3 {
   oneof _leading_underscore_oneof {
     int32 option = 34;
   }
+
+  optional string DEPRECATED_foo = 35;
+  optional string ID = 36;
+  optional string a_b_notification = 37;
+  optional string __DEPRECATED_Bar = 38;
+  optional string not_DEPRECATED_foo = 39;
 }
 
 message HardKeywordsAllTypesProto3 {
diff --git a/java/lite/pom.xml b/java/lite/pom.xml
index 64a69085f3..d2da130846 100644
--- a/java/lite/pom.xml
+++ b/java/lite/pom.xml
@@ -139,6 +139,8 @@
                     <include>LazyStringArrayList.java</include>
                     <include>LazyStringList.java</include>
                     <include>ListFieldSchema.java</include>
+                    <include>ListFieldSchemaLite.java</include>
+                    <include>ListFieldSchemas.java</include>
                     <include>LongArrayList.java</include>
                     <include>ManifestSchemaFactory.java</include>
                     <include>MapEntryLite.java</include>
diff --git a/java/lite/src/test/java/com/google/protobuf/LiteTest.java b/java/lite/src/test/java/com/google/protobuf/LiteTest.java
index 754ed7d5fc..0c7b8b535b 100644
--- a/java/lite/src/test/java/com/google/protobuf/LiteTest.java
+++ b/java/lite/src/test/java/com/google/protobuf/LiteTest.java
@@ -2423,6 +2423,12 @@ public class LiteTest {
     int unused = TestRecursiveOneof.getDefaultInstance().hashCode();
   }
 
+  @Test
+  public void testParseFromEmptyBytes() throws Exception {
+    assertThat(TestAllTypesLite.parseFrom(new byte[] {}))
+        .isSameInstanceAs(TestAllTypesLite.getDefaultInstance());
+  }
+
   @Test
   public void testParseFromByteBuffer() throws Exception {
     TestAllTypesLite message =
@@ -2718,7 +2724,7 @@ public class LiteTest {
   @Test
   public void testNullExtensionRegistry() throws Exception {
     try {
-      TestAllTypesLite.parseFrom(new byte[] {}, null);
+      TestAllTypesLite.parseFrom(TestUtilLite.getAllLiteSetBuilder().build().toByteArray(), null);
       assertWithMessage("expected exception").fail();
     } catch (NullPointerException expected) {
     }
diff --git a/objectivec/Tests/unittest.proto b/objectivec/Tests/unittest.proto
index 2239fe6928..dc9546db76 100644
--- a/objectivec/Tests/unittest.proto
+++ b/objectivec/Tests/unittest.proto
@@ -1109,11 +1109,11 @@ message TestNestedGroupExtensionOuter {
     repeated group Layer2RepeatedGroup = 2 {
       extensions 3
         // NOTE: extension metadata is not supported due to targets such as
-        // `//third_party/protobuf_legacy_opensource/src:shell_scripts_test`,
+        // `//google/protobuf_legacy_opensource/src:shell_scripts_test`,
         // eee https://screenshot.googleplex.com/Axz2QD8nxjdpyFF
         //[metadata = {
         // NOTE: can't write type there due to some clever build gen code at
-        // http://google3/net/proto2/internal/BUILD;l=1247;rcl=411090862
+        // http://google3/google/protobuf/BUILD;l=1247;rcl=411090862
         // type: "objc.protobuf.tests.TestNestedGroupExtensionInnerExtension",
         // name: "inner",
         // }]
diff --git a/php/BUILD.bazel b/php/BUILD.bazel
index 09cc76524f..cc0ba5b174 100644
--- a/php/BUILD.bazel
+++ b/php/BUILD.bazel
@@ -64,6 +64,7 @@ genrule(
 conformance_test(
     name = "conformance_test",
     failure_list = "//conformance:failure_list_php.txt",
+    maximum_edition = "2023",
     target_compatible_with = select({
         "@platforms//os:osx": ["@platforms//:incompatible"],
         "//conditions:default": [],
@@ -75,6 +76,7 @@ conformance_test(
 conformance_test(
     name = "conformance_test_c",
     failure_list = "//conformance:failure_list_php_c.txt",
+    maximum_edition = "2023",
     target_compatible_with = select({
         "@platforms//os:osx": [],
         "//conditions:default": ["@platforms//:incompatible"],
diff --git a/php/ext/google/protobuf/php-upb.c b/php/ext/google/protobuf/php-upb.c
index 9f653e2c3a..03a3298878 100644
--- a/php/ext/google/protobuf/php-upb.c
+++ b/php/ext/google/protobuf/php-upb.c
@@ -404,7 +404,8 @@ void upb_Status_VAppendErrorFormat(upb_Status* status, const char* fmt,
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #include <stddef.h>
 
@@ -1762,7 +1763,8 @@ const upb_MiniTableFile google_protobuf_descriptor_proto_upb_file_layout = {
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 
 static const char descriptor[12155] = {'\n', ' ', 'g', 'o', 'o', 'g', 'l', 'e', '/', 'p', 'r', 'o', 't', 'o', 'b', 'u', 'f', '/', 'd', 'e', 's', 'c', 'r', 'i', 'p', 
@@ -3119,6 +3121,7 @@ static upb_MessageValue jsondec_bool(jsondec* d, const upb_FieldDef* f) {
 /* Composite types (array/message/map) ****************************************/
 
 static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Array* arr = upb_Message_Mutable(msg, f, d->arena).array;
 
   jsondec_arrstart(d);
@@ -3132,6 +3135,7 @@ static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 }
 
 static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Map* map = upb_Message_Mutable(msg, f, d->arena).map;
   const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
   const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumber(entry, 1);
@@ -3153,6 +3157,7 @@ static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 
 static void jsondec_tomsg(jsondec* d, upb_Message* msg,
                           const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (upb_MessageDef_WellKnownType(m) == kUpb_WellKnown_Unspecified) {
     jsondec_object(d, msg, m);
   } else {
@@ -3173,6 +3178,7 @@ static upb_MessageValue jsondec_msg(jsondec* d, const upb_FieldDef* f) {
 
 static void jsondec_field(jsondec* d, upb_Message* msg,
                           const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView name;
   const upb_FieldDef* f;
   const upb_FieldDef* preserved;
@@ -3238,6 +3244,7 @@ static void jsondec_field(jsondec* d, upb_Message* msg,
 
 static void jsondec_object(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   jsondec_objstart(d);
   while (jsondec_objnext(d)) {
     jsondec_field(d, msg, m);
@@ -3338,6 +3345,7 @@ static int64_t jsondec_unixtime(int y, int m, int d, int h, int min, int s) {
 
 static void jsondec_timestamp(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue seconds;
   upb_MessageValue nanos;
   upb_StringView str = jsondec_string(d);
@@ -3403,6 +3411,7 @@ malformed:
 
 static void jsondec_duration(jsondec* d, upb_Message* msg,
                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue seconds;
   upb_MessageValue nanos;
   upb_StringView str = jsondec_string(d);
@@ -3435,6 +3444,7 @@ static void jsondec_duration(jsondec* d, upb_Message* msg,
 
 static void jsondec_listvalue(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* value_m = upb_FieldDef_MessageSubDef(values_f);
   const upb_MiniTable* value_layout = upb_MessageDef_MiniTable(value_m);
@@ -3453,6 +3463,7 @@ static void jsondec_listvalue(jsondec* d, upb_Message* msg,
 
 static void jsondec_struct(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* entry_m = upb_FieldDef_MessageSubDef(fields_f);
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(entry_m, 2);
@@ -3475,6 +3486,7 @@ static void jsondec_struct(jsondec* d, upb_Message* msg,
 
 static void jsondec_wellknownvalue(jsondec* d, upb_Message* msg,
                                    const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue val;
   const upb_FieldDef* f;
   upb_Message* submsg;
@@ -3563,6 +3575,7 @@ static upb_StringView jsondec_mask(jsondec* d, const char* buf,
 
 static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   /* repeated string paths = 1; */
   const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_Array* arr = upb_Message_Mutable(msg, paths_f, d->arena).array;
@@ -3586,6 +3599,7 @@ static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
 
 static void jsondec_anyfield(jsondec* d, upb_Message* msg,
                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (upb_MessageDef_WellKnownType(m) == kUpb_WellKnown_Unspecified) {
     /* For regular types: {"@type": "[user type]", "f1": <V1>, "f2": <V2>}
      * where f1, f2, etc. are the normal fields of this type. */
@@ -3604,6 +3618,7 @@ static void jsondec_anyfield(jsondec* d, upb_Message* msg,
 
 static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
                                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* type_url_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* type_m;
   upb_StringView type_url = jsondec_string(d);
@@ -3633,6 +3648,7 @@ static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
 }
 
 static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   /* string type_url = 1;
    * bytes value = 2; */
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 2);
@@ -3701,6 +3717,7 @@ static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
 
 static void jsondec_wrapper(jsondec* d, upb_Message* msg,
                             const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_JsonMessageValue val = jsondec_value(d, value_f);
   UPB_ASSUME(val.ignore == false);  // Wrapper cannot be an enum.
@@ -3709,6 +3726,7 @@ static void jsondec_wrapper(jsondec* d, upb_Message* msg,
 
 static void jsondec_wellknown(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   switch (upb_MessageDef_WellKnownType(m)) {
     case kUpb_WellKnown_Any:
       jsondec_any(d, msg, m);
@@ -3749,6 +3767,7 @@ static void jsondec_wellknown(jsondec* d, upb_Message* msg,
 
 static bool upb_JsonDecoder_Decode(jsondec* const d, upb_Message* const msg,
                                    const upb_MessageDef* const m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (UPB_SETJMP(d->err)) return false;
 
   jsondec_tomsg(d, msg, m);
@@ -5137,10 +5156,8 @@ bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* m,
                              const upb_MiniTableField* f,
                              upb_Message* map_entry_message, upb_Arena* arena) {
   UPB_ASSERT(!upb_Message_IsFrozen(map_entry_message));
-
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_mini_table = upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  const upb_MiniTable* map_entry_mini_table =
+      upb_MiniTable_MapEntrySubMessage(m, f);
   UPB_ASSERT(map_entry_mini_table);
   const upb_MiniTableField* map_entry_key_field =
       upb_MiniTable_MapKey(map_entry_mini_table);
@@ -6043,9 +6060,9 @@ static upb_Map* upb_Message_Map_DeepClone(const upb_Map* map,
                                           const upb_MiniTableField* f,
                                           upb_Message* clone,
                                           upb_Arena* arena) {
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_table = upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  UPB_ASSERT(!upb_Message_IsFrozen(clone));
+  const upb_MiniTable* map_entry_table =
+      upb_MiniTable_MapEntrySubMessage(mini_table, f);
   UPB_ASSERT(map_entry_table);
 
   const upb_MiniTableField* key_field = upb_MiniTable_MapKey(map_entry_table);
@@ -6087,6 +6104,7 @@ static bool upb_Message_Array_DeepClone(const upb_Array* array,
                                         const upb_MiniTable* mini_table,
                                         const upb_MiniTableField* field,
                                         upb_Message* clone, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(clone));
   UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
   upb_Array* cloned_array = upb_Array_DeepClone(
       array, upb_MiniTableField_CType(field),
@@ -6112,6 +6130,7 @@ static bool upb_Clone_ExtensionValue(
 upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
                                const upb_MiniTable* mini_table,
                                upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   upb_StringView empty_string = upb_StringView_FromDataAndSize(NULL, 0);
   // Only copy message area skipping upb_Message_Internal.
   memcpy(dst + 1, src + 1, mini_table->UPB_PRIVATE(size) - sizeof(upb_Message));
@@ -6138,10 +6157,10 @@ upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
             if (dst_sub_message == NULL) {
               return NULL;
             }
-            _upb_Message_SetTaggedMessagePtr(
-                dst, mini_table, field,
-                UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(dst_sub_message,
-                                                        is_empty));
+            UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
+            (dst, field,
+             UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(dst_sub_message,
+                                                     is_empty));
           }
         } break;
         case kUpb_CType_String:
@@ -6218,6 +6237,7 @@ upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
 
 bool upb_Message_DeepCopy(upb_Message* dst, const upb_Message* src,
                           const upb_MiniTable* mini_table, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   upb_Message_Clear(dst, mini_table);
   return _upb_Message_Copy(dst, src, mini_table, arena) != NULL;
 }
@@ -6234,6 +6254,7 @@ upb_Message* upb_Message_DeepClone(const upb_Message* msg,
 // Performs a shallow copy. TODO: Extend to handle unknown fields.
 void upb_Message_ShallowCopy(upb_Message* dst, const upb_Message* src,
                              const upb_MiniTable* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   memcpy(dst, src, m->UPB_PRIVATE(size));
 }
 
@@ -7284,12 +7305,12 @@ bool upb_MiniTable_SetSubMessage(upb_MiniTable* table,
       return false;
   }
 
-  upb_MiniTableSub* table_sub =
-      (void*)&table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)];
+  int idx = field->UPB_PRIVATE(submsg_index);
+  upb_MiniTableSub* table_subs = (void*)table->UPB_PRIVATE(subs);
   // TODO: Add this assert back once YouTube is updated to not call
   // this function repeatedly.
   // UPB_ASSERT(UPB_PRIVATE(_upb_MiniTable_IsEmpty)(table_sub->submsg));
-  *table_sub = upb_MiniTableSub_FromMessage(sub);
+  table_subs[idx] = upb_MiniTableSub_FromMessage(sub);
   return true;
 }
 
@@ -9854,6 +9875,7 @@ UPB_FORCEINLINE
 void* fastdecode_getfield(upb_Decoder* d, const char* ptr, upb_Message* msg,
                           uint64_t* data, uint64_t* hasbits,
                           fastdecode_arr* farr, int valbytes, upb_card card) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   switch (card) {
     case CARD_s: {
       uint8_t hasbit_index = *data >> 24;
@@ -10229,6 +10251,7 @@ UPB_NOINLINE
 static const char* fastdecode_verifyutf8(upb_Decoder* d, const char* ptr,
                                          upb_Message* msg, intptr_t table,
                                          uint64_t hasbits, uint64_t data) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView* dst = (upb_StringView*)data;
   if (!_upb_Decoder_VerifyUtf8Inline(dst->data, dst->size)) {
     _upb_FastDecoder_ErrorJmp(d, kUpb_DecodeStatus_BadUtf8);
@@ -10274,6 +10297,7 @@ UPB_NOINLINE
 static const char* fastdecode_longstring_noutf8(
     struct upb_Decoder* d, const char* ptr, upb_Message* msg, intptr_t table,
     uint64_t hasbits, uint64_t data) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView* dst = (upb_StringView*)data;
   FASTDECODE_LONGSTRING(d, ptr, msg, table, hasbits, dst, false);
 }
@@ -11974,6 +11998,7 @@ const upb_Extension* UPB_PRIVATE(_upb_Message_Getexts)(
 
 upb_Extension* UPB_PRIVATE(_upb_Message_GetOrCreateExtension)(
     struct upb_Message* msg, const upb_MiniTableExtension* e, upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Extension* ext = (upb_Extension*)UPB_PRIVATE(_upb_Message_Getext)(msg, e);
   if (ext) return ext;
   if (!UPB_PRIVATE(_upb_Message_Realloc)(msg, sizeof(upb_Extension), a))
@@ -11999,6 +12024,7 @@ const double kUpb_NaN = NAN;
 
 bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
                                        upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const size_t overhead = sizeof(upb_Message_Internal);
 
   upb_Message_Internal* in = UPB_PRIVATE(_upb_Message_GetInternal)(msg);
@@ -12035,21 +12061,19 @@ bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
 }
 
 #if UPB_TRACING_ENABLED
-static void (*_new_message_trace_handler)(const upb_MiniTable*,
-                                          const upb_Arena*);
+static void (*_message_trace_handler)(const upb_MiniTable*, const upb_Arena*);
 
-void UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(
-    void (*new_message_trace_handler)(const upb_MiniTable*, const upb_Arena*)) {
-  _new_message_trace_handler = new_message_trace_handler;
+void upb_Message_LogNewMessage(const upb_MiniTable* m, const upb_Arena* arena) {
+  if (_message_trace_handler) {
+    _message_trace_handler(m, arena);
+  }
 }
 
-void UPB_PRIVATE(upb_Message_LogNewMessage)(const upb_MiniTable* mini_table,
-                                            const upb_Arena* arena) {
-  if (_new_message_trace_handler) {
-    _new_message_trace_handler(mini_table, arena);
-  }
+void upb_Message_SetNewMessageTraceHandler(void (*handler)(const upb_MiniTable*,
+                                                           const upb_Arena*)) {
+  _message_trace_handler = handler;
 }
-#endif
+#endif  // UPB_TRACING_ENABLED
 
 
 const char _kUpb_ToBase92[] = {
@@ -13673,11 +13697,11 @@ upb_MessageValue upb_FieldDef_Default(const upb_FieldDef* f) {
 }
 
 const upb_MessageDef* upb_FieldDef_MessageSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_CType(f) == kUpb_CType_Message ? f->sub.msgdef : NULL;
+  return upb_FieldDef_IsSubMessage(f) ? f->sub.msgdef : NULL;
 }
 
 const upb_EnumDef* upb_FieldDef_EnumSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_CType(f) == kUpb_CType_Enum ? f->sub.enumdef : NULL;
+  return upb_FieldDef_IsEnum(f) ? f->sub.enumdef : NULL;
 }
 
 const upb_MiniTableField* upb_FieldDef_MiniTable(const upb_FieldDef* f) {
@@ -13775,8 +13799,11 @@ bool upb_FieldDef_HasDefault(const upb_FieldDef* f) { return f->has_default; }
 bool upb_FieldDef_HasPresence(const upb_FieldDef* f) { return f->has_presence; }
 
 bool upb_FieldDef_HasSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_IsSubMessage(f) ||
-         upb_FieldDef_CType(f) == kUpb_CType_Enum;
+  return upb_FieldDef_IsSubMessage(f) || upb_FieldDef_IsEnum(f);
+}
+
+bool upb_FieldDef_IsEnum(const upb_FieldDef* f) {
+  return upb_FieldDef_CType(f) == kUpb_CType_Enum;
 }
 
 bool upb_FieldDef_IsMap(const upb_FieldDef* f) {
@@ -15401,6 +15428,7 @@ upb_MessageValue upb_Message_GetFieldByDef(const upb_Message* msg,
 upb_MutableMessageValue upb_Message_Mutable(upb_Message* msg,
                                             const upb_FieldDef* f,
                                             upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   UPB_ASSERT(upb_FieldDef_IsSubMessage(f) || upb_FieldDef_IsRepeated(f));
   if (upb_FieldDef_HasPresence(f) && !upb_Message_HasFieldByDef(msg, f)) {
     // We need to skip the upb_Message_GetFieldByDef() call in this case.
@@ -15439,6 +15467,7 @@ make:
 
 bool upb_Message_SetFieldByDef(upb_Message* msg, const upb_FieldDef* f,
                                upb_MessageValue val, upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_MiniTableField* m_f = upb_FieldDef_MiniTable(f);
 
   if (upb_MiniTableField_IsExtension(m_f)) {
@@ -15451,6 +15480,7 @@ bool upb_Message_SetFieldByDef(upb_Message* msg, const upb_FieldDef* f,
 }
 
 void upb_Message_ClearFieldByDef(upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_MiniTableField* m_f = upb_FieldDef_MiniTable(f);
 
   if (upb_MiniTableField_IsExtension(m_f)) {
@@ -15461,6 +15491,7 @@ void upb_Message_ClearFieldByDef(upb_Message* msg, const upb_FieldDef* f) {
 }
 
 void upb_Message_ClearByDef(upb_Message* msg, const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Message_Clear(msg, upb_MessageDef_MiniTable(m));
 }
 
@@ -15522,6 +15553,7 @@ bool upb_Message_Next(const upb_Message* msg, const upb_MessageDef* m,
 
 bool _upb_Message_DiscardUnknown(upb_Message* msg, const upb_MessageDef* m,
                                  int depth) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   size_t iter = kUpb_Message_Begin;
   const upb_FieldDef* f;
   upb_MessageValue val;
diff --git a/php/ext/google/protobuf/php-upb.h b/php/ext/google/protobuf/php-upb.h
index 4462920cb6..26cf6d7616 100644
--- a/php/ext/google/protobuf/php-upb.h
+++ b/php/ext/google/protobuf/php-upb.h
@@ -413,113 +413,6 @@ void upb_Status_VAppendErrorFormat(upb_Status* status, const char* fmt,
 #ifndef UPB_MESSAGE_ACCESSORS_H_
 #define UPB_MESSAGE_ACCESSORS_H_
 
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-
-#ifndef UPB_BASE_DESCRIPTOR_CONSTANTS_H_
-#define UPB_BASE_DESCRIPTOR_CONSTANTS_H_
-
-// Must be last.
-
-// The types a field can have. Note that this list is not identical to the
-// types defined in descriptor.proto, which gives INT32 and SINT32 separate
-// types (we distinguish the two with the "integer encoding" enum below).
-// This enum is an internal convenience only and has no meaning outside of upb.
-typedef enum {
-  kUpb_CType_Bool = 1,
-  kUpb_CType_Float = 2,
-  kUpb_CType_Int32 = 3,
-  kUpb_CType_UInt32 = 4,
-  kUpb_CType_Enum = 5,  // Enum values are int32. TODO: rename
-  kUpb_CType_Message = 6,
-  kUpb_CType_Double = 7,
-  kUpb_CType_Int64 = 8,
-  kUpb_CType_UInt64 = 9,
-  kUpb_CType_String = 10,
-  kUpb_CType_Bytes = 11
-} upb_CType;
-
-// The repeated-ness of each field; this matches descriptor.proto.
-typedef enum {
-  kUpb_Label_Optional = 1,
-  kUpb_Label_Required = 2,
-  kUpb_Label_Repeated = 3
-} upb_Label;
-
-// Descriptor types, as defined in descriptor.proto.
-typedef enum {
-  kUpb_FieldType_Double = 1,
-  kUpb_FieldType_Float = 2,
-  kUpb_FieldType_Int64 = 3,
-  kUpb_FieldType_UInt64 = 4,
-  kUpb_FieldType_Int32 = 5,
-  kUpb_FieldType_Fixed64 = 6,
-  kUpb_FieldType_Fixed32 = 7,
-  kUpb_FieldType_Bool = 8,
-  kUpb_FieldType_String = 9,
-  kUpb_FieldType_Group = 10,
-  kUpb_FieldType_Message = 11,
-  kUpb_FieldType_Bytes = 12,
-  kUpb_FieldType_UInt32 = 13,
-  kUpb_FieldType_Enum = 14,
-  kUpb_FieldType_SFixed32 = 15,
-  kUpb_FieldType_SFixed64 = 16,
-  kUpb_FieldType_SInt32 = 17,
-  kUpb_FieldType_SInt64 = 18,
-} upb_FieldType;
-
-#define kUpb_FieldType_SizeOf 19
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-// Convert from upb_FieldType to upb_CType
-UPB_INLINE upb_CType upb_FieldType_CType(upb_FieldType field_type) {
-  static const upb_CType c_type[] = {
-      kUpb_CType_Double,   // kUpb_FieldType_Double
-      kUpb_CType_Float,    // kUpb_FieldType_Float
-      kUpb_CType_Int64,    // kUpb_FieldType_Int64
-      kUpb_CType_UInt64,   // kUpb_FieldType_UInt64
-      kUpb_CType_Int32,    // kUpb_FieldType_Int32
-      kUpb_CType_UInt64,   // kUpb_FieldType_Fixed64
-      kUpb_CType_UInt32,   // kUpb_FieldType_Fixed32
-      kUpb_CType_Bool,     // kUpb_FieldType_Bool
-      kUpb_CType_String,   // kUpb_FieldType_String
-      kUpb_CType_Message,  // kUpb_FieldType_Group
-      kUpb_CType_Message,  // kUpb_FieldType_Message
-      kUpb_CType_Bytes,    // kUpb_FieldType_Bytes
-      kUpb_CType_UInt32,   // kUpb_FieldType_UInt32
-      kUpb_CType_Enum,     // kUpb_FieldType_Enum
-      kUpb_CType_Int32,    // kUpb_FieldType_SFixed32
-      kUpb_CType_Int64,    // kUpb_FieldType_SFixed64
-      kUpb_CType_Int32,    // kUpb_FieldType_SInt32
-      kUpb_CType_Int64,    // kUpb_FieldType_SInt64
-  };
-
-  // -1 here because the enum is one-based but the table is zero-based.
-  return c_type[field_type - 1];
-}
-
-UPB_INLINE bool upb_FieldType_IsPackable(upb_FieldType field_type) {
-  // clang-format off
-  const unsigned kUnpackableTypes =
-      (1 << kUpb_FieldType_String) |
-      (1 << kUpb_FieldType_Bytes) |
-      (1 << kUpb_FieldType_Message) |
-      (1 << kUpb_FieldType_Group);
-  // clang-format on
-  return (1 << field_type) & ~kUnpackableTypes;
-}
-
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
-
-
-#endif /* UPB_BASE_DESCRIPTOR_CONSTANTS_H_ */
 #ifndef UPB_BASE_STRING_VIEW_H_
 #define UPB_BASE_STRING_VIEW_H_
 
@@ -827,6 +720,109 @@ void upb_Arena_SetTraceHandler(void (*initArenaTraceHandler)(const upb_Arena*,
 #include <stddef.h>
 
 
+#ifndef UPB_BASE_DESCRIPTOR_CONSTANTS_H_
+#define UPB_BASE_DESCRIPTOR_CONSTANTS_H_
+
+// Must be last.
+
+// The types a field can have. Note that this list is not identical to the
+// types defined in descriptor.proto, which gives INT32 and SINT32 separate
+// types (we distinguish the two with the "integer encoding" enum below).
+// This enum is an internal convenience only and has no meaning outside of upb.
+typedef enum {
+  kUpb_CType_Bool = 1,
+  kUpb_CType_Float = 2,
+  kUpb_CType_Int32 = 3,
+  kUpb_CType_UInt32 = 4,
+  kUpb_CType_Enum = 5,  // Enum values are int32. TODO: rename
+  kUpb_CType_Message = 6,
+  kUpb_CType_Double = 7,
+  kUpb_CType_Int64 = 8,
+  kUpb_CType_UInt64 = 9,
+  kUpb_CType_String = 10,
+  kUpb_CType_Bytes = 11
+} upb_CType;
+
+// The repeated-ness of each field; this matches descriptor.proto.
+typedef enum {
+  kUpb_Label_Optional = 1,
+  kUpb_Label_Required = 2,
+  kUpb_Label_Repeated = 3
+} upb_Label;
+
+// Descriptor types, as defined in descriptor.proto.
+typedef enum {
+  kUpb_FieldType_Double = 1,
+  kUpb_FieldType_Float = 2,
+  kUpb_FieldType_Int64 = 3,
+  kUpb_FieldType_UInt64 = 4,
+  kUpb_FieldType_Int32 = 5,
+  kUpb_FieldType_Fixed64 = 6,
+  kUpb_FieldType_Fixed32 = 7,
+  kUpb_FieldType_Bool = 8,
+  kUpb_FieldType_String = 9,
+  kUpb_FieldType_Group = 10,
+  kUpb_FieldType_Message = 11,
+  kUpb_FieldType_Bytes = 12,
+  kUpb_FieldType_UInt32 = 13,
+  kUpb_FieldType_Enum = 14,
+  kUpb_FieldType_SFixed32 = 15,
+  kUpb_FieldType_SFixed64 = 16,
+  kUpb_FieldType_SInt32 = 17,
+  kUpb_FieldType_SInt64 = 18,
+} upb_FieldType;
+
+#define kUpb_FieldType_SizeOf 19
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Convert from upb_FieldType to upb_CType
+UPB_INLINE upb_CType upb_FieldType_CType(upb_FieldType field_type) {
+  static const upb_CType c_type[] = {
+      kUpb_CType_Double,   // kUpb_FieldType_Double
+      kUpb_CType_Float,    // kUpb_FieldType_Float
+      kUpb_CType_Int64,    // kUpb_FieldType_Int64
+      kUpb_CType_UInt64,   // kUpb_FieldType_UInt64
+      kUpb_CType_Int32,    // kUpb_FieldType_Int32
+      kUpb_CType_UInt64,   // kUpb_FieldType_Fixed64
+      kUpb_CType_UInt32,   // kUpb_FieldType_Fixed32
+      kUpb_CType_Bool,     // kUpb_FieldType_Bool
+      kUpb_CType_String,   // kUpb_FieldType_String
+      kUpb_CType_Message,  // kUpb_FieldType_Group
+      kUpb_CType_Message,  // kUpb_FieldType_Message
+      kUpb_CType_Bytes,    // kUpb_FieldType_Bytes
+      kUpb_CType_UInt32,   // kUpb_FieldType_UInt32
+      kUpb_CType_Enum,     // kUpb_FieldType_Enum
+      kUpb_CType_Int32,    // kUpb_FieldType_SFixed32
+      kUpb_CType_Int64,    // kUpb_FieldType_SFixed64
+      kUpb_CType_Int32,    // kUpb_FieldType_SInt32
+      kUpb_CType_Int64,    // kUpb_FieldType_SInt64
+  };
+
+  // -1 here because the enum is one-based but the table is zero-based.
+  return c_type[field_type - 1];
+}
+
+UPB_INLINE bool upb_FieldType_IsPackable(upb_FieldType field_type) {
+  // clang-format off
+  const unsigned kUnpackableTypes =
+      (1 << kUpb_FieldType_String) |
+      (1 << kUpb_FieldType_Bytes) |
+      (1 << kUpb_FieldType_Message) |
+      (1 << kUpb_FieldType_Group);
+  // clang-format on
+  return (1 << field_type) & ~kUnpackableTypes;
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+
+#endif /* UPB_BASE_DESCRIPTOR_CONSTANTS_H_ */
+
 #ifndef UPB_MESSAGE_INTERNAL_ARRAY_H_
 #define UPB_MESSAGE_INTERNAL_ARRAY_H_
 
@@ -1409,6 +1405,7 @@ UPB_API_INLINE bool upb_MiniTableEnum_CheckValue(const upb_MiniTableEnum* e,
 #ifndef UPB_MINI_TABLE_INTERNAL_MESSAGE_H_
 #define UPB_MINI_TABLE_INTERNAL_MESSAGE_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
 
@@ -1540,34 +1537,44 @@ UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_GetFieldByIndex(
   return &m->UPB_ONLYBITS(fields)[i];
 }
 
-UPB_INLINE const union upb_MiniTableSub* UPB_PRIVATE(
+UPB_INLINE const union upb_MiniTableSub UPB_PRIVATE(
     _upb_MiniTable_GetSubByIndex)(const struct upb_MiniTable* m, uint32_t i) {
-  return &m->UPB_PRIVATE(subs)[i];
+  return m->UPB_PRIVATE(subs)[i];
+}
+
+UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_SubMessage(
+    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
+  if (upb_MiniTableField_CType(f) != kUpb_CType_Message) {
+    return NULL;
+  }
+  return m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)].UPB_PRIVATE(submsg);
 }
 
 UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_GetSubMessageTable(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  UPB_ASSERT(upb_MiniTableField_CType(f) == kUpb_CType_Message);
-  const struct upb_MiniTable* ret = upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  const struct upb_MiniTable* ret = upb_MiniTable_SubMessage(m, f);
   UPB_ASSUME(ret);
   return UPB_PRIVATE(_upb_MiniTable_IsEmpty)(ret) ? NULL : ret;
 }
 
-UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_SubMessage(
+UPB_API_INLINE bool upb_MiniTable_FieldIsLinked(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  if (upb_MiniTableField_CType(f) != kUpb_CType_Message) {
-    return NULL;
-  }
-  return upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  return upb_MiniTable_GetSubMessageTable(m, f) != NULL;
+}
+
+UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_MapEntrySubMessage(
+    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
+  UPB_ASSERT(upb_MiniTable_FieldIsLinked(m, f));  // Map entries must be linked.
+  UPB_ASSERT(upb_MiniTableField_IsMap(f));        // Function precondition.
+  return upb_MiniTable_SubMessage(m, f);
 }
 
 UPB_API_INLINE const struct upb_MiniTableEnum* upb_MiniTable_GetSubEnumTable(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
   UPB_ASSERT(upb_MiniTableField_CType(f) == kUpb_CType_Enum);
-  return upb_MiniTableSub_Enum(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  return m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)].UPB_PRIVATE(
+      subenum);
 }
 
 UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_MapKey(
@@ -1586,11 +1593,6 @@ UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_MapValue(
   return f;
 }
 
-UPB_API_INLINE bool upb_MiniTable_FieldIsLinked(
-    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  return upb_MiniTable_GetSubMessageTable(m, f) != NULL;
-}
-
 // Computes a bitmask in which the |m->required_count| lowest bits are set.
 //
 // Sample output:
@@ -1645,10 +1647,20 @@ UPB_API_INLINE int upb_MiniTable_FieldCount(const upb_MiniTable* m);
 UPB_API_INLINE const upb_MiniTable* upb_MiniTable_GetSubMessageTable(
     const upb_MiniTable* m, const upb_MiniTableField* f);
 
-// Returns the MiniTable for a message field if it is a submessage.
+// Returns the MiniTable for a message field if it is a submessage, otherwise
+// returns NULL.
+//
+// WARNING: if dynamic tree shaking is in use, the return value may be the
+// "empty", zero-field placeholder message instead of the real message type.
+// If the message is later linked, this function will begin returning the real
+// message type.
 UPB_API_INLINE const upb_MiniTable* upb_MiniTable_SubMessage(
     const upb_MiniTable* m, const upb_MiniTableField* f);
 
+// Returns the MiniTable for a map field.  The given field must refer to a map.
+UPB_API_INLINE const upb_MiniTable* upb_MiniTable_MapEntrySubMessage(
+    const upb_MiniTable* m, const upb_MiniTableField* f);
+
 // Returns the MiniTableEnum for a message field, NULL if the field is unlinked.
 UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTable_GetSubEnumTable(
     const upb_MiniTable* m, const upb_MiniTableField* f);
@@ -1829,6 +1841,7 @@ UPB_INLINE uint64_t upb_BigEndian64(uint64_t val) {
 #ifndef UPB_MINI_TABLE_INTERNAL_EXTENSION_H_
 #define UPB_MINI_TABLE_INTERNAL_EXTENSION_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
 
@@ -1858,6 +1871,9 @@ upb_MiniTableExtension_Number(const struct upb_MiniTableExtension* e) {
 
 UPB_API_INLINE const struct upb_MiniTable* upb_MiniTableExtension_GetSubMessage(
     const struct upb_MiniTableExtension* e) {
+  if (upb_MiniTableExtension_CType(e) != kUpb_CType_Message) {
+    return NULL;
+  }
   return upb_MiniTableSub_Message(e->UPB_PRIVATE(sub));
 }
 
@@ -1866,6 +1882,11 @@ UPB_API_INLINE void upb_MiniTableExtension_SetSubMessage(
   e->UPB_PRIVATE(sub).UPB_PRIVATE(submsg) = m;
 }
 
+UPB_INLINE upb_FieldRep UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(
+    const struct upb_MiniTableExtension* e) {
+  return UPB_PRIVATE(_upb_MiniTableField_GetRep)(&e->UPB_PRIVATE(field));
+}
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
@@ -2454,18 +2475,19 @@ typedef struct upb_Message_Internal {
 } upb_Message_Internal;
 
 #ifdef UPB_TRACING_ENABLED
-void UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(
-    void (*newMessageTraceHandler)(const upb_MiniTable*, const upb_Arena*));
-void UPB_PRIVATE(upb_Message_LogNewMessage)(const upb_MiniTable* mini_table,
-                                            const upb_Arena* arena);
-#endif
+UPB_API void upb_Message_LogNewMessage(const upb_MiniTable* m,
+                                       const upb_Arena* arena);
+UPB_API void upb_Message_SetNewMessageTraceHandler(
+    void (*handler)(const upb_MiniTable*, const upb_Arena*));
+#endif  // UPB_TRACING_ENABLED
 
 // Inline version upb_Message_New(), for internal use.
 UPB_INLINE struct upb_Message* _upb_Message_New(const upb_MiniTable* m,
                                                 upb_Arena* a) {
 #ifdef UPB_TRACING_ENABLED
-  UPB_PRIVATE(upb_Message_LogNewMessage)(m, a);
-#endif
+  upb_Message_LogNewMessage(m, a);
+#endif  // UPB_TRACING_ENABLED
+
   const int size = m->UPB_PRIVATE(size);
   struct upb_Message* msg = (struct upb_Message*)upb_Arena_Malloc(a, size);
   if (UPB_UNLIKELY(!msg)) return NULL;
@@ -2675,6 +2697,12 @@ UPB_INLINE bool UPB_PRIVATE(_upb_Message_ClearOneofCase)(
   return true;
 }
 
+UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
+    const struct upb_Message* message, const upb_MiniTableField* oneof_field) {
+  UPB_ASSUME(upb_MiniTableField_IsInOneof(oneof_field));
+  return UPB_PRIVATE(_upb_Message_GetOneofCase)(message, oneof_field);
+}
+
 // LINT.ThenChange(GoogleInternalName2)
 
 // Returns false if the message is missing any of its required fields.
@@ -2773,7 +2801,6 @@ UPB_INLINE bool UPB_PRIVATE(_upb_MiniTableField_DataIsZero)(
 //                                       const upb_MiniTableField* field,
 //                                       bool value, upb_Arena* a) {
 //     UPB_ASSUME(field->UPB_PRIVATE(descriptortype) == kUpb_FieldType_Bool);
-//     UPB_ASSUME(upb_MiniTableField_IsScalar(field));
 //     UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
 //                kUpb_FieldRep_1Byte);
 //     upb_Message_SetField(msg, field, &value, a);
@@ -2834,13 +2861,31 @@ UPB_INLINE void _upb_Message_GetExtensionField(
   }
 }
 
-UPB_API_INLINE void upb_Message_SetBaseField(struct upb_Message* msg,
-                                             const upb_MiniTableField* f,
-                                             const void* val) {
-  UPB_ASSERT(!upb_Message_IsFrozen(msg));
-  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
-  UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
-  UPB_PRIVATE(_upb_MiniTableField_DataCopy)
+// NOTE: The default_val is only used for fields that support presence.
+// For repeated/map fields, the resulting upb_Array*/upb_Map* can be NULL if a
+// upb_Array/upb_Map has not been allocated yet. Array/map fields do not have
+// presence, so this is semantically identical to a pointer to an empty
+// array/map, and must be treated the same for all semantic purposes.
+UPB_API_INLINE upb_MessageValue upb_Message_GetField(
+    const struct upb_Message* msg, const upb_MiniTableField* field,
+    upb_MessageValue default_val) {
+  upb_MessageValue ret;
+  if (upb_MiniTableField_IsExtension(field)) {
+    _upb_Message_GetExtensionField(msg, (upb_MiniTableExtension*)field,
+                                   &default_val, &ret);
+  } else {
+    _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
+  }
+  return ret;
+}
+
+UPB_API_INLINE void upb_Message_SetBaseField(struct upb_Message* msg,
+                                             const upb_MiniTableField* f,
+                                             const void* val) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
+  UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
+  UPB_PRIVATE(_upb_MiniTableField_DataCopy)
   (f, UPB_PRIVATE(_upb_Message_MutableDataPtr)(msg, f), val);
 }
 
@@ -2857,6 +2902,516 @@ UPB_API_INLINE bool upb_Message_SetExtension(struct upb_Message* msg,
   return true;
 }
 
+// Sets the value of the given field in the given msg. The return value is true
+// if the operation completed successfully, or false if memory allocation
+// failed.
+UPB_INLINE bool UPB_PRIVATE(_upb_Message_SetField)(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_MessageValue val,
+                                                   upb_Arena* a) {
+  if (upb_MiniTableField_IsExtension(f)) {
+    const upb_MiniTableExtension* ext = (const upb_MiniTableExtension*)f;
+    return upb_Message_SetExtension(msg, ext, &val, a);
+  } else {
+    upb_Message_SetBaseField(msg, f, &val);
+    return true;
+  }
+}
+
+UPB_API_INLINE const upb_Array* upb_Message_GetArray(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* ret;
+  const upb_Array* default_val = NULL;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &ret);
+  return ret;
+}
+
+UPB_API_INLINE bool upb_Message_GetBool(const struct upb_Message* msg,
+                                        const upb_MiniTableField* f,
+                                        bool default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Bool);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_1Byte);
+  upb_MessageValue def;
+  def.bool_val = default_val;
+  return upb_Message_GetField(msg, f, def).bool_val;
+}
+
+UPB_API_INLINE double upb_Message_GetDouble(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            double default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Double);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.double_val = default_val;
+  return upb_Message_GetField(msg, f, def).double_val;
+}
+
+UPB_API_INLINE float upb_Message_GetFloat(const struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          float default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Float);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.float_val = default_val;
+  return upb_Message_GetField(msg, f, def).float_val;
+}
+
+UPB_API_INLINE int32_t upb_Message_GetInt32(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int32_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int32 ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Enum);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.int32_val = default_val;
+  return upb_Message_GetField(msg, f, def).int32_val;
+}
+
+UPB_API_INLINE int64_t upb_Message_GetInt64(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int64_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.int64_val = default_val;
+  return upb_Message_GetField(msg, f, def).int64_val;
+}
+
+UPB_INLINE void UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(
+    const struct upb_Message* msg, const upb_MiniTableField* field) {
+  UPB_UNUSED(msg);
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+#ifndef NDEBUG
+  uintptr_t default_val = 0;
+  uintptr_t tagged;
+  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
+  UPB_ASSERT(!upb_TaggedMessagePtr_IsEmpty(tagged));
+#endif
+}
+
+UPB_API_INLINE const struct upb_Map* upb_Message_GetMap(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(f);
+  UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(msg, f);
+  struct upb_Map* ret;
+  const struct upb_Map* default_val = NULL;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &ret);
+  return ret;
+}
+
+UPB_API_INLINE uintptr_t upb_Message_GetTaggedMessagePtr(
+    const struct upb_Message* msg, const upb_MiniTableField* f,
+    struct upb_Message* default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  uintptr_t tagged;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &tagged);
+  return tagged;
+}
+
+// For internal use only; users cannot set tagged messages because only the
+// parser and the message copier are allowed to directly create an empty
+// message.
+UPB_INLINE void UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)(
+    struct upb_Message* msg, const upb_MiniTableField* f,
+    uintptr_t sub_message) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  upb_Message_SetBaseField(msg, f, &sub_message);
+}
+
+UPB_API_INLINE const struct upb_Message* upb_Message_GetMessage(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  uintptr_t tagged = upb_Message_GetTaggedMessagePtr(msg, f, NULL);
+  return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
+}
+
+UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  return (upb_Array*)upb_Message_GetArray(msg, f);
+}
+
+UPB_API_INLINE struct upb_Map* upb_Message_GetMutableMap(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  return (struct upb_Map*)upb_Message_GetMap(msg, f);
+}
+
+UPB_API_INLINE struct upb_Message* upb_Message_GetMutableMessage(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  return (struct upb_Message*)upb_Message_GetMessage(msg, f);
+}
+
+UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
+    struct upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSERT(arena);
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* array = upb_Message_GetMutableArray(msg, f);
+  if (!array) {
+    array = UPB_PRIVATE(_upb_Array_New)(
+        arena, 4, UPB_PRIVATE(_upb_MiniTableField_ElemSizeLg2)(f));
+    // Check again due to: https://godbolt.org/z/7WfaoKG1r
+    UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+    upb_MessageValue val;
+    val.array_val = array;
+    UPB_PRIVATE(_upb_Message_SetField)(msg, f, val, arena);
+  }
+  return array;
+}
+
+UPB_INLINE struct upb_Map* _upb_Message_GetOrCreateMutableMap(
+    struct upb_Message* msg, const upb_MiniTableField* field, size_t key_size,
+    size_t val_size, upb_Arena* arena) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+  UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(msg, field);
+  struct upb_Map* map = NULL;
+  struct upb_Map* default_map_value = NULL;
+  _upb_Message_GetNonExtensionField(msg, field, &default_map_value, &map);
+  if (!map) {
+    map = _upb_Map_New(arena, key_size, val_size);
+    // Check again due to: https://godbolt.org/z/7WfaoKG1r
+    UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+    upb_Message_SetBaseField(msg, field, &map);
+  }
+  return map;
+}
+
+UPB_API_INLINE struct upb_Map* upb_Message_GetOrCreateMutableMap(
+    struct upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  const upb_MiniTableField* map_entry_key_field =
+      &map_entry_mini_table->UPB_ONLYBITS(fields)[0];
+  const upb_MiniTableField* map_entry_value_field =
+      &map_entry_mini_table->UPB_ONLYBITS(fields)[1];
+  return _upb_Message_GetOrCreateMutableMap(
+      msg, f, _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_key_field)),
+      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_value_field)),
+      arena);
+}
+
+UPB_API_INLINE struct upb_Message* upb_Message_GetOrCreateMutableMessage(
+    struct upb_Message* msg, const upb_MiniTable* mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSERT(arena);
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
+  struct upb_Message* sub_message =
+      *UPB_PTR_AT(msg, f->UPB_ONLYBITS(offset), struct upb_Message*);
+  if (!sub_message) {
+    const upb_MiniTable* sub_mini_table =
+        upb_MiniTable_SubMessage(mini_table, f);
+    UPB_ASSERT(sub_mini_table);
+    sub_message = _upb_Message_New(sub_mini_table, arena);
+    *UPB_PTR_AT(msg, f->UPB_ONLYBITS(offset), struct upb_Message*) =
+        sub_message;
+    UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
+  }
+  return sub_message;
+}
+
+UPB_API_INLINE upb_StringView
+upb_Message_GetString(const struct upb_Message* msg,
+                      const upb_MiniTableField* f, upb_StringView default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_String ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Bytes);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             kUpb_FieldRep_StringView);
+
+  upb_MessageValue def;
+  def.str_val = default_val;
+  return upb_Message_GetField(msg, f, def).str_val;
+}
+
+UPB_API_INLINE uint32_t upb_Message_GetUInt32(const struct upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint32_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt32);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.uint32_val = default_val;
+  return upb_Message_GetField(msg, f, def).uint32_val;
+}
+
+UPB_API_INLINE uint64_t upb_Message_GetUInt64(const struct upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint64_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.uint64_val = default_val;
+  return upb_Message_GetField(msg, f, def).uint64_val;
+}
+
+// BaseField Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE void upb_Message_SetBaseFieldBool(struct upb_Message* msg,
+                                                 const upb_MiniTableField* f,
+                                                 bool value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Bool);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_1Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldDouble(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   double value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Double);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldFloat(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  float value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Float);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldInt32(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int32_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int32 ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Enum);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldInt64(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int64_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldString(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_StringView value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_String ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Bytes);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             kUpb_FieldRep_StringView);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt32(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint32_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt32);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt64(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint64_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetClosedEnum(struct upb_Message* msg,
+                                              const upb_MiniTable* m,
+                                              const upb_MiniTableField* f,
+                                              int32_t value) {
+  UPB_ASSERT(upb_MiniTableField_IsClosedEnum(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  UPB_ASSERT(
+      upb_MiniTableEnum_CheckValue(upb_MiniTable_GetSubEnumTable(m, f), value));
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+// Extension Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetExtensionBool(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, bool value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Bool);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_1Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionDouble(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, double value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Double);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionFloat(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, float value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Float);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int32_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Int32 ||
+             upb_MiniTableExtension_CType(e) == kUpb_CType_Enum);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int64_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Int64);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionString(
+    struct upb_Message* msg, const upb_MiniTableExtension* e,
+    upb_StringView value, upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_String ||
+             upb_MiniTableExtension_CType(e) == kUpb_CType_Bytes);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_StringView);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint32_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_UInt32);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint64_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_UInt64);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+// Universal Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetBool(struct upb_Message* msg,
+                                        const upb_MiniTableField* f, bool value,
+                                        upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionBool(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldBool(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetDouble(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          double value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionDouble(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldDouble(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetFloat(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         float value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionFloat(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldFloat(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt32(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int32_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionInt32(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldInt32(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt64(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int64_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionInt64(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldInt64(msg, f, value), true);
+}
+
+// Sets the value of a message-typed field. The mini_tables of `msg` and
+// `value` must have been linked for this to work correctly.
+UPB_API_INLINE void upb_Message_SetMessage(struct upb_Message* msg,
+                                           const upb_MiniTableField* f,
+                                           struct upb_Message* value) {
+  UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
+  (msg, f, UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(value, false));
+}
+
+// Sets the value of a `string` or `bytes` field. The bytes of the value are not
+// copied, so it is the caller's responsibility to ensure that they remain valid
+// for the lifetime of `msg`. That might be done by copying them into the given
+// arena, or by fusing that arena with the arena the bytes live in, for example.
+UPB_API_INLINE bool upb_Message_SetString(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          upb_StringView value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionString(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldString(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt32(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint32_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionUInt32(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldUInt32(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt64(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint64_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionUInt64(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldUInt64(msg, f, value), true);
+}
+
 UPB_API_INLINE void upb_Message_Clear(struct upb_Message* msg,
                                       const upb_MiniTable* m) {
   UPB_ASSERT(!upb_Message_IsFrozen(msg));
@@ -2898,33 +3453,30 @@ UPB_API_INLINE void upb_Message_ClearExtension(
   }
 }
 
-UPB_INLINE void _upb_Message_AssertMapIsUntagged(
-    const struct upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_UNUSED(msg);
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-#ifndef NDEBUG
-  uintptr_t default_val = 0;
-  uintptr_t tagged;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
-  UPB_ASSERT(!upb_TaggedMessagePtr_IsEmpty(tagged));
-#endif
+UPB_API_INLINE void upb_Message_ClearOneof(struct upb_Message* msg,
+                                           const upb_MiniTable* m,
+                                           const upb_MiniTableField* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+  uint32_t field_number = upb_Message_WhichOneofFieldNumber(msg, f);
+  if (field_number == 0) {
+    // No field in the oneof is set.
+    return;
+  }
+
+  const upb_MiniTableField* field =
+      upb_MiniTable_FindFieldByNumber(m, field_number);
+  upb_Message_ClearBaseField(msg, field);
 }
 
-UPB_INLINE struct upb_Map* _upb_Message_GetOrCreateMutableMap(
-    struct upb_Message* msg, const upb_MiniTableField* field, size_t key_size,
-    size_t val_size, upb_Arena* arena) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-  _upb_Message_AssertMapIsUntagged(msg, field);
-  struct upb_Map* map = NULL;
-  struct upb_Map* default_map_value = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_map_value, &map);
-  if (!map) {
-    map = _upb_Map_New(arena, key_size, val_size);
-    // Check again due to: https://godbolt.org/z/7WfaoKG1r
-    UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-    upb_Message_SetBaseField(msg, field, &map);
+UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
+    struct upb_Message* msg, const upb_MiniTableField* f, size_t size,
+    upb_Arena* arena) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* arr = upb_Message_GetOrCreateMutableArray(msg, f, arena);
+  if (!arr || !UPB_PRIVATE(_upb_Array_ResizeUninitialized)(arr, size, arena)) {
+    return NULL;
   }
-  return map;
+  return upb_Array_MutableDataPtr(arr);
 }
 
 #ifdef __cplusplus
@@ -3047,12 +3599,6 @@ UPB_API_INLINE bool upb_Map_IsFrozen(const upb_Map* map);
 
 #endif /* UPB_MESSAGE_MAP_H_ */
 
-#ifndef UPB_MINI_TABLE_TAGGED_PTR_H_
-#define UPB_MINI_TABLE_TAGGED_PTR_H_
-
-#include <stdint.h>
-
-
 // Public APIs for message operations that do not depend on the schema.
 //
 // MiniTable-based accessors live in accessors.h.
@@ -3090,16 +3636,12 @@ UPB_API void upb_Message_Freeze(upb_Message* msg, const upb_MiniTable* m);
 UPB_API_INLINE bool upb_Message_IsFrozen(const upb_Message* msg);
 
 #ifdef UPB_TRACING_ENABLED
-UPB_INLINE void upb_Message_SetNewMessageTraceHandler(
-    void (*newMessageTraceHandler)(const upb_MiniTable* mini_table,
-                                   const upb_Arena* arena)) {
-  UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(newMessageTraceHandler);
-}
-UPB_INLINE void upb_Message_LogNewMessage(const upb_MiniTable* mini_table,
-                                          const upb_Arena* arena) {
-  UPB_PRIVATE(upb_Message_LogNewMessage)(mini_table, arena);
-}
-#endif
+UPB_API void upb_Message_LogNewMessage(const upb_MiniTable* m,
+                                       const upb_Arena* arena);
+
+UPB_API void upb_Message_SetNewMessageTraceHandler(
+    void (*handler)(const upb_MiniTable* m, const upb_Arena* arena));
+#endif  // UPB_TRACING_ENABLED
 
 #ifdef __cplusplus
 } /* extern "C" */
@@ -3108,6 +3650,12 @@ UPB_INLINE void upb_Message_LogNewMessage(const upb_MiniTable* mini_table,
 
 #endif /* UPB_MESSAGE_MESSAGE_H_ */
 
+#ifndef UPB_MINI_TABLE_TAGGED_PTR_H_
+#define UPB_MINI_TABLE_TAGGED_PTR_H_
+
+#include <stdint.h>
+
+
 // Must be last.
 
 // When a upb_Message* is stored in a message, array, or map, it is stored in a
@@ -3140,474 +3688,231 @@ UPB_API_INLINE upb_Message* upb_TaggedMessagePtr_GetNonEmptyMessage(
 
 #endif /* UPB_MINI_TABLE_TAGGED_PTR_H_ */
 
-#ifndef UPB_MINI_TABLE_SUB_H_
-#define UPB_MINI_TABLE_SUB_H_
-
-
 // Must be last.
 
-typedef union upb_MiniTableSub upb_MiniTableSub;
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-// Constructors
+// Functions ending in BaseField() take a (upb_MiniTableField*) argument
+// and work only on non-extension fields.
+//
+// Functions ending in Extension() take a (upb_MiniTableExtension*) argument
+// and work only on extensions.
 
-UPB_API_INLINE upb_MiniTableSub
-upb_MiniTableSub_FromEnum(const upb_MiniTableEnum* subenum);
+UPB_API_INLINE void upb_Message_Clear(upb_Message* msg, const upb_MiniTable* m);
 
-UPB_API_INLINE upb_MiniTableSub
-upb_MiniTableSub_FromMessage(const upb_MiniTable* submsg);
+UPB_API_INLINE void upb_Message_ClearBaseField(upb_Message* msg,
+                                               const upb_MiniTableField* f);
 
-// Getters
+UPB_API_INLINE void upb_Message_ClearExtension(upb_Message* msg,
+                                               const upb_MiniTableExtension* e);
 
-UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTableSub_Enum(
-    upb_MiniTableSub sub);
+UPB_API_INLINE void upb_Message_ClearOneof(upb_Message* msg,
+                                           const upb_MiniTable* m,
+                                           const upb_MiniTableField* f);
 
-UPB_API_INLINE const upb_MiniTable* upb_MiniTableSub_Message(
-    upb_MiniTableSub sub);
+UPB_API_INLINE bool upb_Message_HasBaseField(const upb_Message* msg,
+                                             const upb_MiniTableField* f);
 
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
+UPB_API_INLINE bool upb_Message_HasExtension(const upb_Message* msg,
+                                             const upb_MiniTableExtension* e);
 
+UPB_API_INLINE upb_MessageValue
+upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* f,
+                     upb_MessageValue default_val);
 
-#endif /* UPB_MINI_TABLE_SUB_H_ */
+UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
+    const upb_Message* msg, const upb_MiniTableField* field,
+    upb_Message* default_val);
 
-// Must be last.
+UPB_API_INLINE const upb_Array* upb_Message_GetArray(
+    const upb_Message* msg, const upb_MiniTableField* f);
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+UPB_API_INLINE bool upb_Message_GetBool(const upb_Message* msg,
+                                        const upb_MiniTableField* f,
+                                        bool default_val);
 
-// Functions ending in BaseField() take a (upb_MiniTableField*) argument
-// and work only on non-extension fields.
-//
-// Functions ending in Extension() take a (upb_MiniTableExtension*) argument
-// and work only on extensions.
+UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
+                                            const upb_MiniTableField* field,
+                                            double default_val);
 
-UPB_API_INLINE void upb_Message_Clear(upb_Message* msg, const upb_MiniTable* m);
+UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          float default_val);
 
-UPB_API_INLINE void upb_Message_ClearBaseField(upb_Message* msg,
-                                               const upb_MiniTableField* f);
+UPB_API_INLINE int32_t upb_Message_GetInt32(const upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int32_t default_val);
 
-UPB_API_INLINE void upb_Message_ClearExtension(upb_Message* msg,
-                                               const upb_MiniTableExtension* e);
+UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int64_t default_val);
+
+UPB_API_INLINE const upb_Map* upb_Message_GetMap(const upb_Message* msg,
+                                                 const upb_MiniTableField* f);
+
+UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
+    const upb_Message* msg, const upb_MiniTableField* f);
+
+UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
+    upb_Message* msg, const upb_MiniTableField* f);
 
-UPB_API_INLINE bool upb_Message_HasBaseField(const upb_Message* msg,
-                                             const upb_MiniTableField* f);
+UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(upb_Message* msg,
+                                                  const upb_MiniTableField* f);
 
-UPB_API_INLINE bool upb_Message_HasExtension(const upb_Message* msg,
-                                             const upb_MiniTableExtension* e);
+UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
+    upb_Message* msg, const upb_MiniTableField* f);
 
-UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
-                                             const upb_MiniTableField* f,
-                                             const void* val);
+UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
+    upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena);
 
-UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
-                                             const upb_MiniTableExtension* e,
-                                             const void* val, upb_Arena* a);
+UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
+    upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena);
 
-UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
-    const upb_Message* message, const upb_MiniTableField* oneof_field) {
-  UPB_ASSUME(upb_MiniTableField_IsInOneof(oneof_field));
-  return UPB_PRIVATE(_upb_Message_GetOneofCase)(message, oneof_field);
-}
+UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
+    upb_Message* msg, const upb_MiniTable* mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena);
 
-// NOTE: The default_val is only used for fields that support presence.
-// For repeated/map fields, the resulting upb_Array*/upb_Map* can be NULL if a
-// upb_Array/upb_Map has not been allocated yet. Array/map fields do not have
-// presence, so this is semantically identical to a pointer to an empty
-// array/map, and must be treated the same for all semantic purposes.
-UPB_INLINE upb_MessageValue
-upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* field,
-                     upb_MessageValue default_val) {
-  upb_MessageValue ret;
-  if (upb_MiniTableField_IsExtension(field)) {
-    _upb_Message_GetExtensionField(msg, (upb_MiniTableExtension*)field,
-                                   &default_val, &ret);
-  } else {
-    _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  }
-  return ret;
-}
+UPB_API_INLINE upb_StringView
+upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
+                      upb_StringView default_val);
 
-// Sets the value of the given field in the given msg. The return value is true
-// if the operation completed successfully, or false if memory allocation
-// failed.
-UPB_INLINE bool UPB_PRIVATE(_upb_Message_SetField)(
-    upb_Message* msg, const upb_MiniTableField* field, upb_MessageValue val,
-    upb_Arena* a) {
-  if (upb_MiniTableField_IsExtension(field)) {
-    const upb_MiniTableExtension* ext = (const upb_MiniTableExtension*)field;
-    return upb_Message_SetExtension(msg, ext, &val, a);
-  } else {
-    upb_Message_SetBaseField(msg, field, &val);
-    return true;
-  }
-}
+UPB_API_INLINE uint32_t upb_Message_GetUInt32(const upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint32_t default_val);
 
-UPB_API_INLINE bool upb_Message_GetBool(const upb_Message* msg,
-                                        const upb_MiniTableField* field,
-                                        bool default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Bool);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_1Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue def;
-  def.bool_val = default_val;
-  return upb_Message_GetField(msg, field, def).bool_val;
-}
+UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint64_t default_val);
 
-UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
-                                        const upb_MiniTableField* field,
-                                        bool value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Bool);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_1Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.bool_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetClosedEnum(
+    upb_Message* msg, const upb_MiniTable* msg_mini_table,
+    const upb_MiniTableField* f, int32_t value);
 
-UPB_API_INLINE int32_t upb_Message_GetInt32(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            int32_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int32 ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Enum);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+// BaseField Setters ///////////////////////////////////////////////////////////
 
-  upb_MessageValue def;
-  def.int32_val = default_val;
-  return upb_Message_GetField(msg, field, def).int32_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
+                                             const upb_MiniTableField* f,
+                                             const void* val);
 
-UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         int32_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int32 ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Enum);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.int32_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldBool(struct upb_Message* msg,
+                                                 const upb_MiniTableField* f,
+                                                 bool value);
 
-UPB_API_INLINE uint32_t upb_Message_GetUInt32(const upb_Message* msg,
-                                              const upb_MiniTableField* field,
-                                              uint32_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt32);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE void upb_Message_SetBaseFieldDouble(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   double value);
 
-  upb_MessageValue def;
-  def.uint32_val = default_val;
-  return upb_Message_GetField(msg, field, def).uint32_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldFloat(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  float value);
 
-UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          uint32_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt32);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.uint32_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldInt32(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int32_t value);
 
-UPB_API_INLINE void upb_Message_SetClosedEnum(
-    upb_Message* msg, const upb_MiniTable* msg_mini_table,
-    const upb_MiniTableField* field, int32_t value) {
-  UPB_ASSERT(upb_MiniTableField_IsClosedEnum(field));
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  UPB_ASSERT(upb_MiniTableEnum_CheckValue(
-      upb_MiniTable_GetSubEnumTable(msg_mini_table, field), value));
-  upb_Message_SetBaseField(msg, field, &value);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldInt64(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int64_t value);
 
-UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            int64_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE void upb_Message_SetBaseFieldString(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_StringView value);
 
-  upb_MessageValue def;
-  def.int64_val = default_val;
-  return upb_Message_GetField(msg, field, def).int64_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt32(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint32_t value);
 
-UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         int64_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.int64_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt64(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint64_t value);
 
-UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
-                                              const upb_MiniTableField* field,
-                                              uint64_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+// Extension Setters ///////////////////////////////////////////////////////////
 
-  upb_MessageValue def;
-  def.uint64_val = default_val;
-  return upb_Message_GetField(msg, field, def).uint64_val;
-}
+UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
+                                             const upb_MiniTableExtension* e,
+                                             const void* value, upb_Arena* a);
 
-UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          uint64_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.uint64_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetExtensionBool(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, bool value,
+    upb_Arena* a);
 
-UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          float default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Float);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE bool upb_Message_SetExtensionDouble(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, double value,
+    upb_Arena* a);
 
-  upb_MessageValue def;
-  def.float_val = default_val;
-  return upb_Message_GetField(msg, field, def).float_val;
-}
+UPB_API_INLINE bool upb_Message_SetExtensionFloat(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, float value,
+    upb_Arena* a);
 
-UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         float value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Float);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.float_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetExtensionInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int32_t value,
+    upb_Arena* a);
 
-UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            double default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Double);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE bool upb_Message_SetExtensionInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int64_t value,
+    upb_Arena* a);
 
-  upb_MessageValue def;
-  def.double_val = default_val;
-  return upb_Message_GetField(msg, field, def).double_val;
-}
+UPB_API_INLINE bool upb_Message_SetExtensionString(
+    struct upb_Message* msg, const upb_MiniTableExtension* e,
+    upb_StringView value, upb_Arena* a);
 
-UPB_API_INLINE bool upb_Message_SetDouble(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          double value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Double);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.double_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetExtensionUInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint32_t value,
+    upb_Arena* a);
 
-UPB_API_INLINE upb_StringView
-upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
-                      upb_StringView default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_String ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Bytes);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_StringView);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE bool upb_Message_SetExtensionUInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint64_t value,
+    upb_Arena* a);
 
-  upb_MessageValue def;
-  def.str_val = default_val;
-  return upb_Message_GetField(msg, field, def).str_val;
-}
+// Universal Setters ///////////////////////////////////////////////////////////
 
-// Sets the value of a `string` or `bytes` field. The bytes of the value are not
-// copied, so it is the caller's responsibility to ensure that they remain valid
-// for the lifetime of `msg`. That might be done by copying them into the given
-// arena, or by fusing that arena with the arena the bytes live in, for example.
-UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          upb_StringView value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_String ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Bytes);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_StringView);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.str_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
+                                        const upb_MiniTableField* f, bool value,
+                                        upb_Arena* a);
 
-UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
-    const upb_Message* msg, const upb_MiniTableField* field,
-    upb_Message* default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_TaggedMessagePtr tagged;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
-  return tagged;
-}
+UPB_API_INLINE bool upb_Message_SetDouble(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          double value, upb_Arena* a);
 
-UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  upb_TaggedMessagePtr tagged =
-      upb_Message_GetTaggedMessagePtr(msg, field, NULL);
-  return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
-}
+UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         float value, upb_Arena* a);
 
-UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  return (upb_Message*)upb_Message_GetMessage(msg, field);
-}
+UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int32_t value, upb_Arena* a);
 
-// For internal use only; users cannot set tagged messages because only the
-// parser and the message copier are allowed to directly create an empty
-// message.
-UPB_API_INLINE void _upb_Message_SetTaggedMessagePtr(
-    upb_Message* msg, const upb_MiniTable* mini_table,
-    const upb_MiniTableField* field, upb_TaggedMessagePtr sub_message) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  UPB_ASSERT(upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]));
-  upb_Message_SetBaseField(msg, field, &sub_message);
-}
+UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int64_t value, upb_Arena* a);
 
-// Sets the value of a message-typed field. The `mini_table` and `field`
-// parameters belong to `msg`, not `sub_message`. The mini_tables of `msg` and
-// `sub_message` must have been linked for this to work correctly.
 UPB_API_INLINE void upb_Message_SetMessage(upb_Message* msg,
-                                           const upb_MiniTable* mini_table,
-                                           const upb_MiniTableField* field,
-                                           upb_Message* sub_message) {
-  _upb_Message_SetTaggedMessagePtr(
-      msg, mini_table, field,
-      UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(sub_message, false));
-}
+                                           const upb_MiniTableField* f,
+                                           upb_Message* value);
 
-UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
-    upb_Message* msg, const upb_MiniTable* mini_table,
-    const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSERT(arena);
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  upb_Message* sub_message =
-      *UPB_PTR_AT(msg, field->UPB_ONLYBITS(offset), upb_Message*);
-  if (!sub_message) {
-    const upb_MiniTable* sub_mini_table = upb_MiniTableSub_Message(
-        mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]);
-    UPB_ASSERT(sub_mini_table);
-    sub_message = _upb_Message_New(sub_mini_table, arena);
-    *UPB_PTR_AT(msg, field->UPB_ONLYBITS(offset), upb_Message*) = sub_message;
-    UPB_PRIVATE(_upb_Message_SetPresence)(msg, field);
-  }
-  return sub_message;
-}
+UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          upb_StringView value, upb_Arena* a);
 
-UPB_API_INLINE const upb_Array* upb_Message_GetArray(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* ret;
-  const upb_Array* default_val = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  return ret;
-}
+UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint32_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  return (upb_Array*)upb_Message_GetArray(msg, field);
-}
+UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint64_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
-    upb_Message* msg, const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSERT(arena);
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* array = upb_Message_GetMutableArray(msg, field);
-  if (!array) {
-    array = UPB_PRIVATE(_upb_Array_New)(
-        arena, 4, UPB_PRIVATE(_upb_MiniTableField_ElemSizeLg2)(field));
-    // Check again due to: https://godbolt.org/z/7WfaoKG1r
-    UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-    upb_MessageValue val;
-    val.array_val = array;
-    UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, arena);
-  }
-  return array;
-}
+////////////////////////////////////////////////////////////////////////////////
 
 UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
-    upb_Message* msg, const upb_MiniTableField* field, size_t size,
-    upb_Arena* arena) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* arr = upb_Message_GetOrCreateMutableArray(msg, field, arena);
-  if (!arr || !UPB_PRIVATE(_upb_Array_ResizeUninitialized)(arr, size, arena)) {
-    return NULL;
-  }
-  return upb_Array_MutableDataPtr(arr);
-}
-
-UPB_API_INLINE const upb_Map* upb_Message_GetMap(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-  _upb_Message_AssertMapIsUntagged(msg, field);
-  upb_Map* ret;
-  const upb_Map* default_val = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  return ret;
-}
-
-UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  return (upb_Map*)upb_Message_GetMap(msg, field);
-}
+    upb_Message* msg, const upb_MiniTableField* f, size_t size,
+    upb_Arena* arena);
 
-UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
-    upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
-    const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  const upb_MiniTableField* map_entry_key_field =
-      &map_entry_mini_table->UPB_ONLYBITS(fields)[0];
-  const upb_MiniTableField* map_entry_value_field =
-      &map_entry_mini_table->UPB_ONLYBITS(fields)[1];
-  return _upb_Message_GetOrCreateMutableMap(
-      msg, field,
-      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_key_field)),
-      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_value_field)),
-      arena);
-}
+UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
+    const upb_Message* message, const upb_MiniTableField* oneof_field);
 
 // Updates a map entry given an entry message.
 bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* mini_table,
@@ -3674,6 +3979,41 @@ UPB_INLINE void _upb_msg_map_set_value(void* msg, const void* val,
 #define UPB_MINI_TABLE_DECODE_H_
 
 
+#ifndef UPB_MINI_TABLE_SUB_H_
+#define UPB_MINI_TABLE_SUB_H_
+
+
+// Must be last.
+
+typedef union upb_MiniTableSub upb_MiniTableSub;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Constructors
+
+UPB_API_INLINE upb_MiniTableSub
+upb_MiniTableSub_FromEnum(const upb_MiniTableEnum* subenum);
+
+UPB_API_INLINE upb_MiniTableSub
+upb_MiniTableSub_FromMessage(const upb_MiniTable* submsg);
+
+// Getters
+
+UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTableSub_Enum(
+    upb_MiniTableSub sub);
+
+UPB_API_INLINE const upb_MiniTable* upb_MiniTableSub_Message(
+    upb_MiniTableSub sub);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+
+#endif /* UPB_MINI_TABLE_SUB_H_ */
+
 // Export the newer headers, for legacy users.  New users should include the
 // more specific headers directly.
 // IWYU pragma: begin_exports
@@ -4390,7 +4730,8 @@ TAGBYTES(r)
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
@@ -4494,7 +4835,8 @@ extern const upb_MiniTableFile google_protobuf_descriptor_proto_upb_file_layout;
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
@@ -11455,6 +11797,7 @@ bool upb_FieldDef_HasOptions(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_HasPresence(const upb_FieldDef* f);
 bool upb_FieldDef_HasSubDef(const upb_FieldDef* f);
 uint32_t upb_FieldDef_Index(const upb_FieldDef* f);
+UPB_API bool upb_FieldDef_IsEnum(const upb_FieldDef* f);
 bool upb_FieldDef_IsExtension(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_IsMap(const upb_FieldDef* f);
 bool upb_FieldDef_IsOptional(const upb_FieldDef* f);
@@ -11810,7 +12153,8 @@ const UPB_DESC(FeatureSet) *
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPBDEFS_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPBDEFS_H_
diff --git a/php/src/Google/Protobuf/Internal/Message.php b/php/src/Google/Protobuf/Internal/Message.php
index 21d9c980e0..31e2f29d30 100644
--- a/php/src/Google/Protobuf/Internal/Message.php
+++ b/php/src/Google/Protobuf/Internal/Message.php
@@ -394,7 +394,8 @@ class Message
                 }
                 break;
             case GPBType::STRING:
-                // TODO: Add utf-8 check.
+                // We don't check UTF-8 here; that will be validated by the
+                // setter later.
                 if (!GPBWire::readString($input, $value)) {
                     throw new GPBDecodeException(
                         "Unexpected EOF inside string field.");
diff --git a/php/tests/EncodeDecodeTest.php b/php/tests/EncodeDecodeTest.php
index 276528d26e..abf95cca00 100644
--- a/php/tests/EncodeDecodeTest.php
+++ b/php/tests/EncodeDecodeTest.php
@@ -683,6 +683,21 @@ class EncodeDecodeTest extends TestBase
         $m->mergeFromString(hex2bin('7201'));
     }
 
+    public function testDecodeInvalidStringDataBadUtf8()
+    {
+        $this->expectException(Exception::class);
+
+        $m = new TestMessage();
+        $m->mergeFromString(hex2bin('720180'));
+    }
+
+    public function testDecodeValidStringData()
+    {
+        $m = new TestMessage();
+        $m->mergeFromString(hex2bin('720161'));
+        $this->assertSame('a', $m->getOptionalString());
+    }
+
     public function testDecodeInvalidBytesLengthMiss()
     {
         $this->expectException(Exception::class);
diff --git a/protobuf.bzl b/protobuf.bzl
index 7db5146a0f..9a05897894 100644
--- a/protobuf.bzl
+++ b/protobuf.bzl
@@ -80,6 +80,7 @@ def _proto_gen_impl(ctx):
     srcs = ctx.files.srcs
     langs = ctx.attr.langs or []
     out_type = ctx.attr.out_type
+    enable_editions = ctx.attr.enable_editions
     deps = depset(direct = ctx.files.srcs)
     source_dir = _SourceDir(ctx)
     gen_dir = _GenDir(ctx).rstrip("/")
@@ -130,6 +131,8 @@ def _proto_gen_impl(ctx):
     generated_files = []
     for src in srcs:
         args = []
+        if enable_editions:
+            args.append("--experimental_editions")
 
         in_gen_dir = src.root.path == gen_dir
         if in_gen_dir:
@@ -231,6 +234,7 @@ Args:
   srcs: Protocol Buffers definition files (.proto) to run the protocol compiler
     against.
   deps: a list of dependency labels; must be other proto libraries.
+  enable_editions: if true, sets the --experimental_editions flag.
   includes: a list of include paths to .proto files.
   protoc: the label of the protocol compiler to generate the sources.
   plugin: the label of the protocol compiler plugin to be passed to the protocol
@@ -247,6 +251,7 @@ _proto_gen = rule(
     attrs = {
         "srcs": attr.label_list(allow_files = True),
         "deps": attr.label_list(providers = [ProtoGenInfo]),
+        "enable_editions": attr.bool(),
         "includes": attr.string_list(),
         "protoc": attr.label(
             cfg = "exec",
@@ -655,6 +660,7 @@ def _source_proto_library(
         protoc = Label("//:protoc"),
         testonly = None,
         visibility = ["//visibility:public"],
+        enable_editions = False,
         **kwargs):
     """Bazel rule to create generated protobuf code from proto source files for
     languages not well supported by Bazel yet.  This will output the generated
@@ -699,6 +705,7 @@ def _source_proto_library(
             srcs = proto_deps,
             protoc = protoc,
             includes = includes,
+            enable_editions = enable_editions,
         )
         full_deps.append(":%s_deps_genproto" % name)
 
@@ -712,6 +719,7 @@ def _source_proto_library(
         protoc = protoc,
         testonly = testonly,
         visibility = visibility,
+        enable_editions = enable_editions,
     )
 
     native.filegroup(
diff --git a/protobuf_deps.bzl b/protobuf_deps.bzl
index 558540cc7f..9fee18a2a6 100644
--- a/protobuf_deps.bzl
+++ b/protobuf_deps.bzl
@@ -2,6 +2,7 @@
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 load("//python/dist:python_downloads.bzl", "python_nuget_package", "python_source_archive")
+load("//python/dist:system_python.bzl", "system_python")
 
 PROTOBUF_MAVEN_ARTIFACTS = [
     "com.google.caliper:caliper:1.0-beta-3",
@@ -43,6 +44,8 @@ def protobuf_deps():
         _github_archive(
             name = "com_google_absl",
             repo = "https://github.com/abseil/abseil-cpp",
+            # TODO: use Layout::WithStaticSizes in SerialArenaChunk when we update
+            # abseil to new release.
             commit = "4a2c63365eff8823a5221db86ef490e828306f9d",  # Abseil LTS 20240116.0
             sha256 = "f49929d22751bf70dd61922fb1fd05eb7aec5e7a7f870beece79a6e28f0a06c1",
         )
@@ -102,6 +105,12 @@ def protobuf_deps():
             url = "https://github.com/bazelbuild/rules_python/releases/download/0.26.0/rules_python-0.26.0.tar.gz",
         )
 
+    if not native.existing_rule("system_python"):
+        system_python(
+            name = "system_python",
+            minimum_python_version = "3.7",
+        )
+
     if not native.existing_rule("rules_jvm_external"):
         _github_archive(
             name = "rules_jvm_external",
diff --git a/protos/protos.h b/protos/protos.h
index 0bac4b683e..87547f9008 100644
--- a/protos/protos.h
+++ b/protos/protos.h
@@ -340,29 +340,28 @@ ABSL_MUST_USE_RESULT bool HasExtension(
   return HasExtension(protos::Ptr(message), id);
 }
 
-template <typename T, typename Extendee, typename Extension,
-          typename = EnableIfProtosClass<T>, typename = EnableIfMutableProto<T>>
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>,
+          typename = EnableIfMutableProto<T>>
 void ClearExtension(
     Ptr<T> message,
-    const ::protos::internal::ExtensionIdentifier<Extendee, Extension>& id) {
+    const ::protos::internal::ExtensionIdentifier<T, Extension>& id) {
   static_assert(!std::is_const_v<T>, "");
   upb_Message_ClearExtension(internal::GetInternalMsg(message),
                              id.mini_table_ext());
 }
 
-template <typename T, typename Extendee, typename Extension,
-          typename = EnableIfProtosClass<T>>
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>>
 void ClearExtension(
     T* message,
-    const ::protos::internal::ExtensionIdentifier<Extendee, Extension>& id) {
+    const ::protos::internal::ExtensionIdentifier<T, Extension>& id) {
   ClearExtension(::protos::Ptr(message), id);
 }
 
-template <typename T, typename Extendee, typename Extension,
-          typename = EnableIfProtosClass<T>, typename = EnableIfMutableProto<T>>
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>,
+          typename = EnableIfMutableProto<T>>
 absl::Status SetExtension(
     Ptr<T> message,
-    const ::protos::internal::ExtensionIdentifier<Extendee, Extension>& id,
+    const ::protos::internal::ExtensionIdentifier<T, Extension>& id,
     const Extension& value) {
   static_assert(!std::is_const_v<T>);
   auto* message_arena = static_cast<upb_Arena*>(message->GetInternalArena());
@@ -371,11 +370,24 @@ absl::Status SetExtension(
                                           internal::GetInternalMsg(&value));
 }
 
-template <typename T, typename Extendee, typename Extension,
-          typename = EnableIfProtosClass<T>, typename = EnableIfMutableProto<T>>
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>,
+          typename = EnableIfMutableProto<T>>
 absl::Status SetExtension(
     Ptr<T> message,
-    const ::protos::internal::ExtensionIdentifier<Extendee, Extension>& id,
+    const ::protos::internal::ExtensionIdentifier<T, Extension>& id,
+    Ptr<Extension> value) {
+  static_assert(!std::is_const_v<T>);
+  auto* message_arena = static_cast<upb_Arena*>(message->GetInternalArena());
+  return ::protos::internal::SetExtension(internal::GetInternalMsg(message),
+                                          message_arena, id.mini_table_ext(),
+                                          internal::GetInternalMsg(value));
+}
+
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>,
+          typename = EnableIfMutableProto<T>>
+absl::Status SetExtension(
+    Ptr<T> message,
+    const ::protos::internal::ExtensionIdentifier<T, Extension>& id,
     Extension&& value) {
   Extension ext = std::move(value);
   static_assert(!std::is_const_v<T>);
@@ -386,25 +398,28 @@ absl::Status SetExtension(
       internal::GetInternalMsg(&ext), extension_arena);
 }
 
-template <typename T, typename Extendee, typename Extension,
-          typename = EnableIfProtosClass<T>>
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>>
 absl::Status SetExtension(
-    T* message,
-    const ::protos::internal::ExtensionIdentifier<Extendee, Extension>& id,
+    T* message, const ::protos::internal::ExtensionIdentifier<T, Extension>& id,
     const Extension& value) {
   return ::protos::SetExtension(::protos::Ptr(message), id, value);
 }
 
-template <typename T, typename Extendee, typename Extension,
-          typename = EnableIfProtosClass<T>>
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>>
 absl::Status SetExtension(
-    T* message,
-    const ::protos::internal::ExtensionIdentifier<Extendee, Extension>& id,
+    T* message, const ::protos::internal::ExtensionIdentifier<T, Extension>& id,
     Extension&& value) {
   return ::protos::SetExtension(::protos::Ptr(message), id,
                                 std::forward<Extension>(value));
 }
 
+template <typename T, typename Extension, typename = EnableIfProtosClass<T>>
+absl::Status SetExtension(
+    T* message, const ::protos::internal::ExtensionIdentifier<T, Extension>& id,
+    Ptr<Extension> value) {
+  return ::protos::SetExtension(::protos::Ptr(message), id, value);
+}
+
 template <typename T, typename Extendee, typename Extension,
           typename = EnableIfProtosClass<T>>
 absl::StatusOr<Ptr<const Extension>> GetExtension(
diff --git a/protos_generator/gen_messages.cc b/protos_generator/gen_messages.cc
index 06a0d8e4b0..c8277a57c5 100644
--- a/protos_generator/gen_messages.cc
+++ b/protos_generator/gen_messages.cc
@@ -7,11 +7,14 @@
 
 #include "protos_generator/gen_messages.h"
 
+#include <cstddef>
 #include <string>
 #include <vector>
 
 #include "google/protobuf/descriptor.pb.h"
+#include "absl/strings/ascii.h"
 #include "absl/strings/str_cat.h"
+#include "absl/strings/string_view.h"
 #include "google/protobuf/descriptor.h"
 #include "protos_generator/gen_accessors.h"
 #include "protos_generator/gen_enums.h"
@@ -120,6 +123,55 @@ void WriteModelAccessDeclaration(const protobuf::Descriptor* descriptor,
   output("};\n");
 }
 
+std::string UnderscoresToCamelCase(absl::string_view input,
+                                   bool cap_next_letter) {
+  std::string result;
+
+  for (size_t i = 0; i < input.size(); i++) {
+    if (absl::ascii_islower(input[i])) {
+      if (cap_next_letter) {
+        result += absl::ascii_toupper(input[i]);
+      } else {
+        result += input[i];
+      }
+      cap_next_letter = false;
+    } else if (absl::ascii_isupper(input[i])) {
+      // Capital letters are left as-is.
+      result += input[i];
+      cap_next_letter = false;
+    } else if (absl::ascii_isdigit(input[i])) {
+      result += input[i];
+      cap_next_letter = true;
+    } else {
+      cap_next_letter = true;
+    }
+  }
+  return result;
+}
+
+std::string FieldConstantName(const protobuf::FieldDescriptor* field) {
+  std::string field_name = UnderscoresToCamelCase(field->name(), true);
+  std::string result = absl::StrCat("k", field_name, "FieldNumber");
+
+  if (!field->is_extension() &&
+      field->containing_type()->FindFieldByCamelcaseName(
+          field->camelcase_name()) != field) {
+    // This field's camelcase name is not unique, add field number to make it
+    // unique.
+    absl::StrAppend(&result, "_", field->number());
+  }
+  return result;
+}
+
+void WriteConstFieldNumbers(Output& output,
+                            const protobuf::Descriptor* descriptor) {
+  for (auto field : FieldRange(descriptor)) {
+    output("static constexpr ::uint32_t $0 = $1;\n", FieldConstantName(field),
+           field->number());
+  }
+  output("\n\n");
+}
+
 void WriteModelPublicDeclaration(
     const protobuf::Descriptor* descriptor,
     const std::vector<const protobuf::FieldDescriptor*>& file_exts,
@@ -178,6 +230,7 @@ void WriteModelPublicDeclaration(
       )cc",
       ClassName(descriptor));
   output("\n");
+  WriteConstFieldNumbers(output, descriptor);
   output(
       R"cc(
         private:
diff --git a/protos_generator/tests/test_generated.cc b/protos_generator/tests/test_generated.cc
index ffa3d5cb8d..208a1be80a 100644
--- a/protos_generator/tests/test_generated.cc
+++ b/protos_generator/tests/test_generated.cc
@@ -5,10 +5,12 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
+#include <cstdint>
 #include <iterator>
 #include <limits>
 #include <memory>
 #include <string>
+#include <type_traits>
 #include <utility>
 #include <vector>
 
@@ -23,10 +25,13 @@
 #include "protos_generator/tests/no_package.upb.proto.h"
 #include "protos_generator/tests/test_model.upb.proto.h"
 #include "upb/mem/arena.h"
+#include "upb/mem/arena.hpp"
 
 namespace {
 
 using ::protos_generator::test::protos::ChildModel1;
+using ::protos_generator::test::protos::container_ext;
+using ::protos_generator::test::protos::ContainerExtension;
 using ::protos_generator::test::protos::other_ext;
 using ::protos_generator::test::protos::RED;
 using ::protos_generator::test::protos::TestEnum;
@@ -38,7 +43,6 @@ using ::protos_generator::test::protos::TestModel_Category_VIDEO;
 using ::protos_generator::test::protos::theme;
 using ::protos_generator::test::protos::ThemeExtension;
 using ::testing::ElementsAre;
-using ::testing::HasSubstr;
 
 // C++17 port of C++20 `requires`
 template <typename... T, typename F>
@@ -441,7 +445,7 @@ TEST(CppGeneratedCode, RepeatedScalarIterator) {
   EXPECT_EQ(sum, 5 + 16 + 27);
   // Access by const reference.
   sum = 0;
-  for (const int& i : *test_model.mutable_value_array()) {
+  for (const auto& i : *test_model.mutable_value_array()) {
     sum += i;
   }
   EXPECT_EQ(sum, 5 + 16 + 27);
@@ -550,7 +554,7 @@ TEST(CppGeneratedCode, RepeatedFieldProxyForMessages) {
   }
 
   i = 0;
-  for (auto child : *test_model.mutable_child_models()) {
+  for (const auto& child : *test_model.mutable_child_models()) {
     if (i++ == 0) {
       EXPECT_EQ(child.child_str1(), kTestStr1);
     } else {
@@ -724,6 +728,70 @@ TEST(CppGeneratedCode, SetExtension) {
   EXPECT_EQ(::protos::internal::GetInternalMsg(*ext), prior_message);
 }
 
+TEST(CppGeneratedCode, SetExtensionWithPtr) {
+  ::protos::Arena arena_model;
+  ::protos::Ptr<TestModel> model =
+      ::protos::CreateMessage<TestModel>(arena_model);
+  void* prior_message;
+  {
+    // Use a nested scope to make sure the arenas are fused correctly.
+    ::protos::Arena arena;
+    ::protos::Ptr<ThemeExtension> extension1 =
+        ::protos::CreateMessage<ThemeExtension>(arena);
+    extension1->set_ext_name("Hello World");
+    prior_message = ::protos::internal::GetInternalMsg(extension1);
+    EXPECT_EQ(false, ::protos::HasExtension(model, theme));
+    auto res = ::protos::SetExtension(model, theme, extension1);
+    EXPECT_EQ(true, res.ok());
+  }
+  EXPECT_EQ(true, ::protos::HasExtension(model, theme));
+  auto ext = ::protos::GetExtension(model, theme);
+  EXPECT_TRUE(ext.ok());
+  EXPECT_NE(::protos::internal::GetInternalMsg(*ext), prior_message);
+}
+
+#ifndef _MSC_VER
+TEST(CppGeneratedCode, SetExtensionShouldNotCompileForWrongType) {
+  ::protos::Arena arena;
+  ::protos::Ptr<TestModel> model = ::protos::CreateMessage<TestModel>(arena);
+  ThemeExtension extension1;
+  ContainerExtension extension2;
+
+  const auto canSetExtension = [&](auto l) {
+    return Requires<decltype(model)>(l);
+  };
+  EXPECT_TRUE(canSetExtension(
+      [](auto p) -> decltype(::protos::SetExtension(p, theme, extension1)) {}));
+  // Wrong extension value type should fail to compile.
+  EXPECT_TRUE(!canSetExtension(
+      [](auto p) -> decltype(::protos::SetExtension(p, theme, extension2)) {}));
+  // Wrong extension id with correct extension type should fail to compile.
+  EXPECT_TRUE(
+      !canSetExtension([](auto p) -> decltype(::protos::SetExtension(
+                                      p, container_ext, extension1)) {}));
+}
+#endif
+
+TEST(CppGeneratedCode, SetExtensionWithPtrSameArena) {
+  ::protos::Arena arena;
+  ::protos::Ptr<TestModel> model = ::protos::CreateMessage<TestModel>(arena);
+  void* prior_message;
+  {
+    // Use a nested scope to make sure the arenas are fused correctly.
+    ::protos::Ptr<ThemeExtension> extension1 =
+        ::protos::CreateMessage<ThemeExtension>(arena);
+    extension1->set_ext_name("Hello World");
+    prior_message = ::protos::internal::GetInternalMsg(extension1);
+    EXPECT_EQ(false, ::protos::HasExtension(model, theme));
+    auto res = ::protos::SetExtension(model, theme, extension1);
+    EXPECT_EQ(true, res.ok());
+  }
+  EXPECT_EQ(true, ::protos::HasExtension(model, theme));
+  auto ext = ::protos::GetExtension(model, theme);
+  EXPECT_TRUE(ext.ok());
+  EXPECT_NE(::protos::internal::GetInternalMsg(*ext), prior_message);
+}
+
 TEST(CppGeneratedCode, SetExtensionFusingFailureShouldCopy) {
   // Use an initial block to disallow fusing.
   char initial_block[1000];
@@ -1134,6 +1202,11 @@ TEST(CppGeneratedCode, HasExtensionAndRegistry) {
   EXPECT_TRUE(::protos::HasExtension(&parsed_model, theme));
 }
 
+TEST(CppGeneratedCode, FieldNumberConstants) {
+  static_assert(TestModel::kChildMapFieldNumber == 225);
+  EXPECT_EQ(225, TestModel::kChildMapFieldNumber);
+}
+
 // TODO : Add BUILD rule to test failures below.
 #ifdef TEST_CLEAR_MESSAGE_FAILURE
 TEST(CppGeneratedCode, ClearConstMessageShouldFail) {
diff --git a/protos_generator/tests/test_model.proto b/protos_generator/tests/test_model.proto
index 24b4406e95..34c875aed4 100644
--- a/protos_generator/tests/test_model.proto
+++ b/protos_generator/tests/test_model.proto
@@ -14,6 +14,8 @@ import "protos_generator/tests/child_model.proto";
 message TestModelContainer {
   repeated TestModel models = 1;
   optional ChildModel3 proto_3_child = 2;
+  extensions 10000 to max
+  [verification = UNVERIFIED];
 }
 
 message TestModel {
@@ -138,6 +140,17 @@ extend TestModel {
   optional ThemeExtension theme = 12001;
 }
 
+message ContainerExtension {
+  extend TestModelContainer {
+    optional ContainerExtension container_extension = 12004;
+  }
+  optional string ext_container_name = 1;
+}
+
+extend TestModelContainer {
+  optional ContainerExtension container_ext = 12005;
+}
+
 message OtherExtension {
   optional string ext2_name = 1;
 }
diff --git a/python/build_targets.bzl b/python/build_targets.bzl
index 0b18fe19b9..1014514a4b 100644
--- a/python/build_targets.bzl
+++ b/python/build_targets.bzl
@@ -416,6 +416,11 @@ def build_targets(name):
         srcs = ["google/protobuf/internal/wire_format_test.py"],
     )
 
+    internal_py_test(
+        name = "proto_test",
+        srcs = ["google/protobuf/internal/proto_test.py"],
+    )
+
     native.cc_library(
         name = "proto_api",
         hdrs = ["google/protobuf/proto_api.h"],
diff --git a/python/google/protobuf/internal/descriptor_test.py b/python/google/protobuf/internal/descriptor_test.py
index ce16d0363a..2c8423efac 100755
--- a/python/google/protobuf/internal/descriptor_test.py
+++ b/python/google/protobuf/internal/descriptor_test.py
@@ -884,6 +884,10 @@ class DescriptorCopyToProtoTest(unittest.TestCase):
         name: 'FOREIGN_BAX'
         number: 32
       >
+      value: <
+        name: 'FOREIGN_LARGE'
+        number: 123456
+      >
       """
 
     self._InternalTestCopyToProto(
diff --git a/python/google/protobuf/internal/enum_type_wrapper.py b/python/google/protobuf/internal/enum_type_wrapper.py
index cc65fc0bc8..1fa6ab9f58 100644
--- a/python/google/protobuf/internal/enum_type_wrapper.py
+++ b/python/google/protobuf/internal/enum_type_wrapper.py
@@ -12,6 +12,8 @@ on proto classes.  For usage, see:
   reflection_test.py
 """
 
+import sys
+
 __author__ = 'rabsatt@google.com (Kevin Rabsatt)'
 
 
@@ -99,3 +101,12 @@ class EnumTypeWrapper(object):
       pass  # fall out to break exception chaining
     raise AttributeError('Enum {} has no value defined for name {!r}'.format(
         self._enum_type.name, name))
+
+  def __or__(self, other):
+    """Returns the union type of self and other."""
+    if sys.version_info >= (3, 10):
+      return type(self) | other
+    else:
+      raise NotImplementedError(
+          'You may not use | on EnumTypes (or classes) below python 3.10'
+      )
diff --git a/python/google/protobuf/internal/json_format_test.py b/python/google/protobuf/internal/json_format_test.py
index 6c5a5e32c8..965557eb1e 100644
--- a/python/google/protobuf/internal/json_format_test.py
+++ b/python/google/protobuf/internal/json_format_test.py
@@ -1439,7 +1439,7 @@ class JsonFormatTest(JsonFormatBase):
   def testInvalidAny(self):
     message = any_pb2.Any()
     text = '{"@type": "type.googleapis.com/google.protobuf.Int32Value"}'
-    self.assertRaisesRegex(KeyError, 'value', json_format.Parse, text, message)
+    self.assertRaisesRegex(json_format.ParseError, 'KeyError: \'value\'', json_format.Parse, text, message)
     text = '{"value": 1234}'
     self.assertRaisesRegex(
         json_format.ParseError,
@@ -1662,6 +1662,12 @@ class JsonFormatTest(JsonFormatBase):
     json_format.Parse(json_string, new_parsed_message)
     self.assertEqual(new_message, new_parsed_message)
 
+  def testOtherParseErrors(self):
+    self.CheckError(
+        '9',
+        "Failed to parse JSON: TypeError: 'int' object is not iterable.",
+    )
+
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/message_test.py b/python/google/protobuf/internal/message_test.py
index 68f1999b16..e42538e1a7 100755
--- a/python/google/protobuf/internal/message_test.py
+++ b/python/google/protobuf/internal/message_test.py
@@ -22,6 +22,7 @@ import operator
 import pickle
 import pydoc
 import sys
+import types
 import unittest
 from unittest import mock
 import warnings
@@ -30,6 +31,7 @@ cmp = lambda x, y: (x > y) - (x < y)
 
 from google.protobuf.internal import api_implementation # pylint: disable=g-import-not-at-top
 from google.protobuf.internal import encoder
+from google.protobuf.internal import enum_type_wrapper
 from google.protobuf.internal import more_extensions_pb2
 from google.protobuf.internal import more_messages_pb2
 from google.protobuf.internal import packed_field_test_pb2
@@ -1314,6 +1316,44 @@ class MessageTest(unittest.TestCase):
     self.assertNotEqual(m, ComparesWithFoo())
     self.assertNotEqual(ComparesWithFoo(), m)
 
+  def testTypeUnion(self, message_module):
+    # Below python 3.10 you cannot create union types with the | operator, so we
+    # skip testing for unions with old versions.
+    if sys.version_info < (3, 10):
+      return
+    enum_type = enum_type_wrapper.EnumTypeWrapper(
+        message_module.TestAllTypes.NestedEnum.DESCRIPTOR
+    )
+    union_type = enum_type | int
+    self.assertIsInstance(union_type, types.UnionType)
+
+    def get_union() -> union_type:
+      return enum_type
+
+    union = get_union()
+    self.assertIsInstance(union, enum_type_wrapper.EnumTypeWrapper)
+    self.assertEqual(
+        union.DESCRIPTOR, message_module.TestAllTypes.NestedEnum.DESCRIPTOR
+    )
+
+  def testIn(self, message_module):
+    m = message_module.TestAllTypes()
+    self.assertNotIn('optional_nested_message', m)
+    self.assertNotIn('oneof_bytes', m)
+    self.assertNotIn('oneof_string', m)
+    with self.assertRaises(ValueError) as e:
+      'repeated_int32' in m
+    with self.assertRaises(ValueError) as e:
+      'repeated_nested_message' in m
+    with self.assertRaises(ValueError) as e:
+      1 in m
+    with self.assertRaises(ValueError) as e:
+      'not_a_field' in m
+    test_util.SetAllFields(m)
+    self.assertIn('optional_nested_message', m)
+    self.assertIn('oneof_bytes', m)
+    self.assertNotIn('oneof_string', m)
+
 
 # Class to test proto2-only features (required, extensions, etc.)
 @testing_refleaks.TestCase
@@ -1345,6 +1385,9 @@ class Proto2Test(unittest.TestCase):
     self.assertTrue(message.HasField('optional_int32'))
     self.assertTrue(message.HasField('optional_bool'))
     self.assertTrue(message.HasField('optional_nested_message'))
+    self.assertIn('optional_int32', message)
+    self.assertIn('optional_bool', message)
+    self.assertIn('optional_nested_message', message)
 
     # Set the fields to non-default values.
     message.optional_int32 = 5
@@ -1363,6 +1406,9 @@ class Proto2Test(unittest.TestCase):
     self.assertFalse(message.HasField('optional_int32'))
     self.assertFalse(message.HasField('optional_bool'))
     self.assertFalse(message.HasField('optional_nested_message'))
+    self.assertNotIn('optional_int32', message)
+    self.assertNotIn('optional_bool', message)
+    self.assertNotIn('optional_nested_message', message)
     self.assertEqual(0, message.optional_int32)
     self.assertEqual(False, message.optional_bool)
     self.assertEqual(0, message.optional_nested_message.bb)
@@ -1689,6 +1735,12 @@ class Proto3Test(unittest.TestCase):
     with self.assertRaises(ValueError):
       message.HasField('repeated_nested_message')
 
+    # Can not test "in" operator.
+    with self.assertRaises(ValueError):
+      'repeated_int32' in message
+    with self.assertRaises(ValueError):
+      'repeated_nested_message' in message
+
     # Fields should default to their type-specific default.
     self.assertEqual(0, message.optional_int32)
     self.assertEqual(0, message.optional_float)
@@ -1699,6 +1751,7 @@ class Proto3Test(unittest.TestCase):
     # Setting a submessage should still return proper presence information.
     message.optional_nested_message.bb = 0
     self.assertTrue(message.HasField('optional_nested_message'))
+    self.assertIn('optional_nested_message', message)
 
     # Set the fields to non-default values.
     message.optional_int32 = 5
diff --git a/python/google/protobuf/internal/proto_test.py b/python/google/protobuf/internal/proto_test.py
new file mode 100644
index 0000000000..6bf5b54471
--- /dev/null
+++ b/python/google/protobuf/internal/proto_test.py
@@ -0,0 +1,34 @@
+# -*- coding: utf-8 -*-
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Tests Nextgen Pythonic protobuf APIs."""
+
+import unittest
+
+from google.protobuf import proto
+
+from google.protobuf.internal import test_util
+from google.protobuf.internal import testing_refleaks
+from google.protobuf.internal import _parameterized
+from google.protobuf import unittest_pb2
+from google.protobuf import unittest_proto3_arena_pb2
+
+@_parameterized.named_parameters(('_proto2', unittest_pb2),
+                                ('_proto3', unittest_proto3_arena_pb2))
+@testing_refleaks.TestCase
+class ProtoTest(unittest.TestCase):
+
+  def testSerializeParse(self, message_module):
+    msg = message_module.TestAllTypes()
+    test_util.SetAllFields(msg)
+    serialized_data = proto.serialize(msg)
+    parsed_msg = proto.parse(message_module.TestAllTypes, serialized_data)
+    self.assertEqual(msg, parsed_msg)
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/python/google/protobuf/internal/python_message.py b/python/google/protobuf/internal/python_message.py
index 34efbfea06..869f2aa731 100755
--- a/python/google/protobuf/internal/python_message.py
+++ b/python/google/protobuf/internal/python_message.py
@@ -1000,6 +1000,21 @@ def _AddUnicodeMethod(unused_message_descriptor, cls):
   cls.__unicode__ = __unicode__
 
 
+def _AddContainsMethod(message_descriptor, cls):
+
+  if message_descriptor.full_name == 'google.protobuf.Struct':
+    def __contains__(self, key):
+      return key in self.fields
+  elif message_descriptor.full_name == 'google.protobuf.ListValue':
+    def __contains__(self, value):
+      return value in self.items()
+  else:
+    def __contains__(self, field):
+      return self.HasField(field)
+
+  cls.__contains__ = __contains__
+
+
 def _BytesForNonRepeatedElement(value, field_number, field_type):
   """Returns the number of bytes needed to serialize a non-repeated element.
   The returned byte count includes space for tag information and any
@@ -1394,6 +1409,7 @@ def _AddMessageMethods(message_descriptor, cls):
   _AddStrMethod(message_descriptor, cls)
   _AddReprMethod(message_descriptor, cls)
   _AddUnicodeMethod(message_descriptor, cls)
+  _AddContainsMethod(message_descriptor, cls)
   _AddByteSizeMethod(message_descriptor, cls)
   _AddSerializeToStringMethod(message_descriptor, cls)
   _AddSerializePartialToStringMethod(message_descriptor, cls)
diff --git a/python/google/protobuf/internal/reflection_test.py b/python/google/protobuf/internal/reflection_test.py
index 459bef345e..171b9cda81 100755
--- a/python/google/protobuf/internal/reflection_test.py
+++ b/python/google/protobuf/internal/reflection_test.py
@@ -594,19 +594,37 @@ class ReflectionTest(unittest.TestCase):
 
   def testEnum_KeysAndValues(self, message_module):
     if message_module == unittest_pb2:
-      keys = ['FOREIGN_FOO', 'FOREIGN_BAR', 'FOREIGN_BAZ', 'FOREIGN_BAX']
-      values = [4, 5, 6, 32]
+      keys = [
+          'FOREIGN_FOO',
+          'FOREIGN_BAR',
+          'FOREIGN_BAZ',
+          'FOREIGN_BAX',
+          'FOREIGN_LARGE',
+      ]
+      values = [4, 5, 6, 32, 123456]
       items = [
           ('FOREIGN_FOO', 4),
           ('FOREIGN_BAR', 5),
           ('FOREIGN_BAZ', 6),
           ('FOREIGN_BAX', 32),
+          ('FOREIGN_LARGE', 123456),
       ]
     else:
-      keys = ['FOREIGN_ZERO', 'FOREIGN_FOO', 'FOREIGN_BAR', 'FOREIGN_BAZ']
-      values = [0, 4, 5, 6]
-      items = [('FOREIGN_ZERO', 0), ('FOREIGN_FOO', 4),
-               ('FOREIGN_BAR', 5), ('FOREIGN_BAZ', 6)]
+      keys = [
+          'FOREIGN_ZERO',
+          'FOREIGN_FOO',
+          'FOREIGN_BAR',
+          'FOREIGN_BAZ',
+          'FOREIGN_LARGE',
+      ]
+      values = [0, 4, 5, 6, 123456]
+      items = [
+          ('FOREIGN_ZERO', 0),
+          ('FOREIGN_FOO', 4),
+          ('FOREIGN_BAR', 5),
+          ('FOREIGN_BAZ', 6),
+          ('FOREIGN_LARGE', 123456),
+      ]
     self.assertEqual(keys,
                      list(message_module.ForeignEnum.keys()))
     self.assertEqual(values,
diff --git a/python/google/protobuf/internal/type_checkers.py b/python/google/protobuf/internal/type_checkers.py
index e152a43f82..04ccc98500 100755
--- a/python/google/protobuf/internal/type_checkers.py
+++ b/python/google/protobuf/internal/type_checkers.py
@@ -22,7 +22,7 @@ TYPE_TO_DESERIALIZE_METHOD: A dictionary with field types and deserialization
 
 __author__ = 'robinson@google.com (Will Robinson)'
 
-import ctypes
+import struct
 import numbers
 
 from google.protobuf.internal import decoder
@@ -34,7 +34,7 @@ _FieldDescriptor = descriptor.FieldDescriptor
 
 
 def TruncateToFourByteFloat(original):
-  return ctypes.c_float(original).value
+  return struct.unpack('<f', struct.pack('<f', original))[0]
 
 
 def ToShortestFloat(original):
diff --git a/python/google/protobuf/internal/well_known_types.py b/python/google/protobuf/internal/well_known_types.py
index 8a0a3b13dd..ea90be3be6 100644
--- a/python/google/protobuf/internal/well_known_types.py
+++ b/python/google/protobuf/internal/well_known_types.py
@@ -497,9 +497,6 @@ class Struct(object):
   def __getitem__(self, key):
     return _GetStructValue(self.fields[key])
 
-  def __contains__(self, item):
-    return item in self.fields
-
   def __setitem__(self, key, value):
     _SetStructValue(self.fields[key], value)
 
diff --git a/python/google/protobuf/internal/well_known_types_test.py b/python/google/protobuf/internal/well_known_types_test.py
index 498d3f28ab..592776634d 100644
--- a/python/google/protobuf/internal/well_known_types_test.py
+++ b/python/google/protobuf/internal/well_known_types_test.py
@@ -515,7 +515,6 @@ class StructTest(unittest.TestCase):
     self.assertEqual(False, struct_list[3])
     self.assertEqual(None, struct_list[4])
     self.assertEqual(inner_struct, struct_list[5])
-    self.assertIn(6, struct_list)
 
     struct_list[1] = 7
     self.assertEqual(7, struct_list[1])
@@ -570,6 +569,36 @@ class StructTest(unittest.TestCase):
     self.assertEqual([6, True, False, None, inner_struct],
                      list(struct['key5'].items()))
 
+  def testInOperator(self):
+    # in operator for Struct
+    struct = struct_pb2.Struct()
+    struct['key'] = 5
+
+    self.assertIn('key', struct)
+    self.assertNotIn('fields', struct)
+    with self.assertRaises(TypeError) as e:
+      1 in struct
+
+    # in operator for ListValue
+    struct_list = struct.get_or_create_list('key2')
+    self.assertIsInstance(struct_list, collections_abc.Sequence)
+    struct_list.extend([6, 'seven', True, False, None])
+    struct_list.add_struct()['subkey'] = 9
+    inner_struct = struct.__class__()
+    inner_struct['subkey'] = 9
+
+    self.assertIn(6, struct_list)
+    self.assertIn('seven', struct_list)
+    self.assertIn(True, struct_list)
+    self.assertIn(False, struct_list)
+    self.assertIn(None, struct_list)
+    self.assertIn(inner_struct, struct_list)
+    self.assertNotIn('values', struct_list)
+    self.assertNotIn(10, struct_list)
+
+    for item in struct_list:
+      self.assertIn(item, struct_list)
+
   def testStructAssignment(self):
     # Tests struct assignment from another struct
     s1 = struct_pb2.Struct()
diff --git a/python/google/protobuf/json_format.py b/python/google/protobuf/json_format.py
index 8a2e24975b..2a6bba9391 100644
--- a/python/google/protobuf/json_format.py
+++ b/python/google/protobuf/json_format.py
@@ -451,13 +451,22 @@ def Parse(
   """
   if not isinstance(text, str):
     text = text.decode('utf-8')
+
   try:
     js = json.loads(text, object_pairs_hook=_DuplicateChecker)
-  except ValueError as e:
+  except Exception as e:
     raise ParseError('Failed to load JSON: {0}.'.format(str(e))) from e
-  return ParseDict(
-      js, message, ignore_unknown_fields, descriptor_pool, max_recursion_depth
-  )
+
+  try:
+    return ParseDict(
+        js, message, ignore_unknown_fields, descriptor_pool, max_recursion_depth
+    )
+  except ParseError as e:
+    raise e
+  except Exception as e:
+    raise ParseError(
+        'Failed to parse JSON: {0}: {1}.'.format(type(e).__name__, str(e))
+    ) from e
 
 
 def ParseDict(
diff --git a/python/google/protobuf/message.py b/python/google/protobuf/message.py
index 3226b6e776..ae9cb147e3 100755
--- a/python/google/protobuf/message.py
+++ b/python/google/protobuf/message.py
@@ -75,6 +75,34 @@ class Message(object):
     """Outputs a human-readable representation of the message."""
     raise NotImplementedError
 
+  def __contains__(self, field_name_or_key):
+    """Checks if a certain field is set for the message.
+
+    Has presence fields return true if the field is set, false if the field is
+    not set. Fields without presence do raise `ValueError` (this includes
+    repeated fields, map fields, and implicit presence fields).
+
+    If field_name is not defined in the message descriptor, `ValueError` will
+    be raised.
+    Note: WKT Struct checks if the key is contained in fields. ListValue checks
+    if the item is contained in the list.
+
+    Args:
+      field_name_or_key: For Struct, the key (str) of the fields map. For
+        ListValue, any type that may be contained in the list. For other
+        messages, name of the field (str) to check for presence.
+
+    Returns:
+      bool: For Struct, whether the item is contained in fields. For ListValue,
+            whether the item is contained in the list. For other message,
+            whether a value has been set for the named field.
+
+    Raises:
+      ValueError: For normal messages,  if the `field_name_or_key` is not a
+                  member of this message or `field_name_or_key` is not a string.
+    """
+    raise NotImplementedError
+
   def MergeFrom(self, other_msg):
     """Merges the contents of the specified message into current message.
 
diff --git a/python/google/protobuf/proto.py b/python/google/protobuf/proto.py
new file mode 100644
index 0000000000..722bbb23fc
--- /dev/null
+++ b/python/google/protobuf/proto.py
@@ -0,0 +1,39 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+"""Contains the Nextgen Pythonic protobuf APIs."""
+
+import typing
+
+from google.protobuf.message import Message
+
+def serialize(message: Message, deterministic: bool=None) -> bytes:
+  """Return the serialized proto.
+
+  Args:
+    message: The proto message to be serialized.
+    deterministic: If true, requests deterministic serialization
+        of the protobuf, with predictable ordering of map keys.
+
+  Returns:
+    A binary bytes representation of the message.
+  """
+  return message.SerializeToString(deterministic=deterministic)
+
+def parse(message_class: typing.Type[Message], payload: bytes) -> Message:
+  """Given a serialized data in binary form, deserialize it into a Message.
+
+  Args:
+    message_class: The message meta class.
+    payload: A serialized bytes in binary form.
+
+  Returns:
+    A new message deserialized from payload.
+  """
+  new_message = message_class()
+  new_message.ParseFromString(payload)
+  return new_message
diff --git a/python/google/protobuf/pyext/message.cc b/python/google/protobuf/pyext/message.cc
index 06f95157c8..39fe35a941 100644
--- a/python/google/protobuf/pyext/message.cc
+++ b/python/google/protobuf/pyext/message.cc
@@ -10,6 +10,7 @@
 
 #include "google/protobuf/pyext/message.h"
 
+#include <Python.h>
 #include <structmember.h>  // A Python header file.
 
 #include <cstdint>
@@ -36,6 +37,7 @@
 #include "google/protobuf/io/coded_stream.h"
 #include "google/protobuf/io/strtod.h"
 #include "google/protobuf/io/zero_copy_stream_impl_lite.h"
+#include "google/protobuf/map_field.h"
 #include "google/protobuf/message.h"
 #include "google/protobuf/text_format.h"
 #include "google/protobuf/unknown_field_set.h"
@@ -85,6 +87,12 @@ class MessageReflectionFriend {
     return reflection->IsLazyField(field) ||
            reflection->IsLazyExtension(message, field);
   }
+  static bool ContainsMapKey(const Reflection* reflection,
+                             const Message& message,
+                             const FieldDescriptor* field,
+                             const MapKey& map_key) {
+    return reflection->ContainsMapKey(message, field, map_key);
+  }
 };
 
 static PyObject* kDESCRIPTOR;
@@ -1293,11 +1301,16 @@ PyObject* HasField(CMessage* self, PyObject* arg) {
   char* field_name;
   Py_ssize_t size;
   field_name = const_cast<char*>(PyUnicode_AsUTF8AndSize(arg, &size));
+  Message* message = self->message;
+
   if (!field_name) {
+    PyErr_Format(PyExc_ValueError,
+                 "The field name passed to message %s"
+                 " is not a str.",
+                 message->GetDescriptor()->name().c_str());
     return nullptr;
   }
 
-  Message* message = self->message;
   bool is_in_oneof;
   const FieldDescriptor* field_descriptor = FindFieldWithOneofs(
       message, absl::string_view(field_name, size), &is_in_oneof);
@@ -2290,6 +2303,48 @@ PyObject* ToUnicode(CMessage* self) {
   return decoded;
 }
 
+PyObject* Contains(CMessage* self, PyObject* arg) {
+  Message* message = self->message;
+  const Descriptor* descriptor = message->GetDescriptor();
+  switch (descriptor->well_known_type()) {
+    case Descriptor::WELLKNOWNTYPE_STRUCT: {
+      // For WKT Struct, check if the key is in the fields.
+      const Reflection* reflection = message->GetReflection();
+      const FieldDescriptor* map_field = descriptor->FindFieldByName("fields");
+      const FieldDescriptor* key_field = map_field->message_type()->map_key();
+      PyObject* py_string = CheckString(arg, key_field);
+      if (!py_string) {
+        PyErr_SetString(PyExc_TypeError,
+                        "The key passed to Struct message must be a str.");
+        return nullptr;
+      }
+      char* value;
+      Py_ssize_t value_len;
+      if (PyBytes_AsStringAndSize(py_string, &value, &value_len) < 0) {
+        Py_DECREF(py_string);
+        Py_RETURN_FALSE;
+      }
+      std::string key_str;
+      key_str.assign(value, value_len);
+      Py_DECREF(py_string);
+
+      MapKey map_key;
+      map_key.SetStringValue(key_str);
+      return PyBool_FromLong(MessageReflectionFriend::ContainsMapKey(
+          reflection, *message, map_field, map_key));
+    }
+    case Descriptor::WELLKNOWNTYPE_LISTVALUE: {
+      // For WKT ListValue, check if the key is in the items.
+      PyObject* items = PyObject_CallMethod(reinterpret_cast<PyObject*>(self),
+                                            "items", nullptr);
+      return PyBool_FromLong(PySequence_Contains(items, arg));
+    }
+    default:
+      // For other messages, check with HasField.
+      return HasField(self, arg);
+  }
+}
+
 // CMessage static methods:
 PyObject* _CheckCalledFromGeneratedFile(PyObject* unused,
                                         PyObject* unused_arg) {
@@ -2338,6 +2393,8 @@ static PyMethodDef Methods[] = {
      "Makes a deep copy of the class."},
     {"__unicode__", (PyCFunction)ToUnicode, METH_NOARGS,
      "Outputs a unicode representation of the message."},
+    {"__contains__", (PyCFunction)Contains, METH_O,
+     "Checks if a message field is set."},
     {"ByteSize", (PyCFunction)ByteSize, METH_NOARGS,
      "Returns the size of the message in bytes."},
     {"Clear", (PyCFunction)Clear, METH_NOARGS, "Clears the message."},
diff --git a/python/google/protobuf/runtime_version.py b/python/google/protobuf/runtime_version.py
index e414e09e9e..7f294b36fb 100644
--- a/python/google/protobuf/runtime_version.py
+++ b/python/google/protobuf/runtime_version.py
@@ -22,17 +22,28 @@ class Domain(Enum):
   PUBLIC = 2
 
 
+# The versions of this Python Protobuf runtime to be changed automatically by
+# the Protobuf release process. Do not edit them manually.
+# These OSS versions are not stripped to avoid merging conflicts.
+OSS_DOMAIN = Domain.PUBLIC
+OSS_MAJOR = 5
+OSS_MINOR = 28
+OSS_PATCH = 0
+OSS_SUFFIX = '-dev'
+
+DOMAIN = OSS_DOMAIN
+MAJOR = OSS_MAJOR
+MINOR = OSS_MINOR
+PATCH = OSS_PATCH
+SUFFIX = OSS_SUFFIX
+
+
 class VersionError(Exception):
   """Exception class for version violation."""
 
 
-# The versions of this Python Protobuf runtime to be changed automatically by
-# the Protobuf release process. Do not edit them manually.
-DOMAIN = Domain.PUBLIC
-MAJOR = 5
-MINOR = 28
-PATCH = 0
-SUFFIX = '-dev'
+def _ReportVersionError(msg):
+  raise VersionError(msg)
 
 
 def ValidateProtobufRuntimeVersion(
@@ -69,28 +80,28 @@ def ValidateProtobufRuntimeVersion(
   )
 
   if gen_domain != DOMAIN:
-    raise VersionError(
+    _ReportVersionError(
         'Detected mismatched Protobuf Gencode/Runtime domains when loading'
         f' {location}: gencode {gen_domain.name} runtime {DOMAIN.name}.'
         ' Cross-domain usage of Protobuf is not supported.'
     )
 
   if gen_major != MAJOR:
-    raise VersionError(
+    _ReportVersionError(
         'Detected mismatched Protobuf Gencode/Runtime major versions when'
         f' loading {location}: gencode {gen_version} runtime {version}.'
         f' Same major version is required. {error_prompt}'
     )
 
   if MINOR < gen_minor or (MINOR == gen_minor and PATCH < gen_patch):
-    raise VersionError(
+    _ReportVersionError(
         'Detected incompatible Protobuf Gencode/Runtime versions when loading'
         f' {location}: gencode {gen_version} runtime {version}. Runtime version'
         f' cannot be older than the linked gencode version. {error_prompt}'
     )
 
   if gen_suffix != SUFFIX:
-    raise VersionError(
+    _ReportVersionError(
         'Detected mismatched Protobuf Gencode/Runtime version suffixes when'
         f' loading {location}: gencode {gen_version} runtime {version}.'
         f' Version suffixes must be the same. {error_prompt}'
diff --git a/python/message.c b/python/message.c
index c0c0882d24..d5213ab1af 100644
--- a/python/message.c
+++ b/python/message.c
@@ -1044,6 +1044,35 @@ static PyObject* PyUpb_Message_HasField(PyObject* _self, PyObject* arg) {
                                      NULL);
 }
 
+static PyObject* PyUpb_Message_Contains(PyObject* _self, PyObject* arg) {
+  const upb_MessageDef* msgdef = PyUpb_Message_GetMsgdef(_self);
+  switch (upb_MessageDef_WellKnownType(msgdef)) {
+    case kUpb_WellKnown_Struct: {
+      // For WKT Struct, check if the key is in the fields.
+      PyUpb_Message* self = (void*)_self;
+      if (PyUpb_Message_IsStub(self)) Py_RETURN_FALSE;
+      upb_Message* msg = PyUpb_Message_GetMsg(self);
+      const upb_FieldDef* f = upb_MessageDef_FindFieldByName(msgdef, "fields");
+      const upb_Map* map = upb_Message_GetFieldByDef(msg, f).map_val;
+      const upb_MessageDef* entry_m = upb_FieldDef_MessageSubDef(f);
+      const upb_FieldDef* key_f = upb_MessageDef_Field(entry_m, 0);
+      upb_MessageValue u_key;
+      if (!PyUpb_PyToUpb(arg, key_f, &u_key, NULL)) return NULL;
+      return PyBool_FromLong(upb_Map_Get(map, u_key, NULL));
+    }
+    case kUpb_WellKnown_ListValue: {
+      // For WKT ListValue, check if the key is in the items.
+      PyUpb_Message* self = (void*)_self;
+      if (PyUpb_Message_IsStub(self)) Py_RETURN_FALSE;
+      PyObject* items = PyObject_CallMethod(_self, "items", NULL);
+      return PyBool_FromLong(PySequence_Contains(items, arg));
+    }
+    default:
+      // For other messages, check with HasField.
+      return PyUpb_Message_HasField(_self, arg);
+  }
+}
+
 static PyObject* PyUpb_Message_FindInitializationErrors(PyObject* _self,
                                                         PyObject* arg);
 
@@ -1642,6 +1671,8 @@ static PyMethodDef PyUpb_Message_Methods[] = {
     // TODO
     //{ "__unicode__", (PyCFunction)ToUnicode, METH_NOARGS,
     //  "Outputs a unicode representation of the message." },
+    {"__contains__", PyUpb_Message_Contains, METH_O,
+     "Checks if a message field is set."},
     {"ByteSize", (PyCFunction)PyUpb_Message_ByteSize, METH_NOARGS,
      "Returns the size of the message in bytes."},
     {"Clear", (PyCFunction)PyUpb_Message_Clear, METH_NOARGS,
diff --git a/python/pb_unit_tests/BUILD b/python/pb_unit_tests/BUILD
index 74b01c8eef..4d6244b0ea 100644
--- a/python/pb_unit_tests/BUILD
+++ b/python/pb_unit_tests/BUILD
@@ -17,8 +17,6 @@ load(":pyproto_test_wrapper.bzl", "pyproto_test_wrapper")
 
 licenses(["notice"])
 
-pyproto_test_wrapper(name = "descriptor_database_test")
-
 pyproto_test_wrapper(name = "descriptor_pool_test")
 
 pyproto_test_wrapper(name = "descriptor_test")
@@ -27,55 +25,14 @@ pyproto_test_wrapper(name = "descriptor_test")
 pyproto_test_wrapper(name = "generator_test")
 # end:github_only
 
-pyproto_test_wrapper(name = "json_format_test")
-
-pyproto_test_wrapper(name = "keywords_test")
-
 pyproto_test_wrapper(name = "message_factory_test")
 
-# begin:github_only
-# This target has different dependencies and fails when using the wrapper
-# TODO: Move this to using pyproto_test_wrapper
-py_test(
-    name = "numpy_test",
-    srcs = ["numpy_test_wrapper.py"],
-    main = "numpy_test_wrapper.py",
-    target_compatible_with = select({
-        "@system_python//:supported": [],
-        "//conditions:default": ["@platforms//:incompatible"],
-    }),
-    deps = [
-        requirement("numpy"),
-        "//python:_message",
-        "//python/google/protobuf/internal/numpy:numpy_test",
-    ],
-)
-# end:github_only
-
-# begin:google_only
-# pyproto_test_wrapper(name = "numpy_test")
-# end:google_only
-
 pyproto_test_wrapper(name = "proto_builder_test")
 
-pyproto_test_wrapper(name = "service_reflection_test")
-
-pyproto_test_wrapper(name = "symbol_database_test")
-
-pyproto_test_wrapper(name = "text_encoding_test")
-
 pyproto_test_wrapper(name = "message_test")
 
 pyproto_test_wrapper(name = "reflection_test")
 
-pyproto_test_wrapper(name = "text_format_test")
-
-pyproto_test_wrapper(name = "unknown_fields_test")
-
-pyproto_test_wrapper(name = "well_known_types_test")
-
-pyproto_test_wrapper(name = "wire_format_test")
-
 filegroup(
     name = "test_files",
     srcs = glob(["*.py"]),
diff --git a/python/pb_unit_tests/descriptor_database_test_wrapper.py b/python/pb_unit_tests/descriptor_database_test_wrapper.py
deleted file mode 100644
index 2e6081fc7c..0000000000
--- a/python/pb_unit_tests/descriptor_database_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.descriptor_database_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/json_format_test_wrapper.py b/python/pb_unit_tests/json_format_test_wrapper.py
deleted file mode 100644
index 27d855cd48..0000000000
--- a/python/pb_unit_tests/json_format_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.json_format_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/keywords_test_wrapper.py b/python/pb_unit_tests/keywords_test_wrapper.py
deleted file mode 100644
index d9401785d0..0000000000
--- a/python/pb_unit_tests/keywords_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.keywords_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/numpy_test_wrapper.py b/python/pb_unit_tests/numpy_test_wrapper.py
deleted file mode 100644
index 62089e9cda..0000000000
--- a/python/pb_unit_tests/numpy_test_wrapper.py
+++ /dev/null
@@ -1,36 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-import unittest
-
-from google.protobuf.internal.numpy.numpy_test import *
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/service_reflection_test_wrapper.py b/python/pb_unit_tests/service_reflection_test_wrapper.py
deleted file mode 100644
index bc0345c217..0000000000
--- a/python/pb_unit_tests/service_reflection_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.service_reflection_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/symbol_database_test_wrapper.py b/python/pb_unit_tests/symbol_database_test_wrapper.py
deleted file mode 100644
index 16ea9656ba..0000000000
--- a/python/pb_unit_tests/symbol_database_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.symbol_database_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/text_encoding_test_wrapper.py b/python/pb_unit_tests/text_encoding_test_wrapper.py
deleted file mode 100644
index 3eb8153baf..0000000000
--- a/python/pb_unit_tests/text_encoding_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.text_encoding_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/text_format_test_wrapper.py b/python/pb_unit_tests/text_format_test_wrapper.py
deleted file mode 100644
index 535561d83c..0000000000
--- a/python/pb_unit_tests/text_format_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.text_format_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/unknown_fields_test_wrapper.py b/python/pb_unit_tests/unknown_fields_test_wrapper.py
deleted file mode 100644
index 1807f6d1ff..0000000000
--- a/python/pb_unit_tests/unknown_fields_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.unknown_fields_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/well_known_types_test_wrapper.py b/python/pb_unit_tests/well_known_types_test_wrapper.py
deleted file mode 100644
index 5006332489..0000000000
--- a/python/pb_unit_tests/well_known_types_test_wrapper.py
+++ /dev/null
@@ -1,36 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.well_known_types_test import *
-import os
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/python/pb_unit_tests/wire_format_test_wrapper.py b/python/pb_unit_tests/wire_format_test_wrapper.py
deleted file mode 100644
index 3b13a2b4b7..0000000000
--- a/python/pb_unit_tests/wire_format_test_wrapper.py
+++ /dev/null
@@ -1,35 +0,0 @@
-# Protocol Buffers - Google's data interchange format
-# Copyright 2023 Google LLC.  All rights reserved.
-# https://developers.google.com/protocol-buffers/
-#
-# Redistribution and use in source and binary forms, with or without
-# modification, are permitted provided that the following conditions are
-# met:
-#
-#     * Redistributions of source code must retain the above copyright
-# notice, this list of conditions and the following disclaimer.
-#     * Redistributions in binary form must reproduce the above
-# copyright notice, this list of conditions and the following disclaimer
-# in the documentation and/or other materials provided with the
-# distribution.
-#     * Neither the name of Google LLC nor the names of its
-# contributors may be used to endorse or promote products derived from
-# this software without specific prior written permission.
-#
-# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-from google.protobuf.internal.wire_format_test import *
-import unittest
-
-if __name__ == '__main__':
-  unittest.main(verbosity=2)
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.c b/ruby/ext/google/protobuf_c/ruby-upb.c
index cc42c374d8..c4cfa69ca9 100644
--- a/ruby/ext/google/protobuf_c/ruby-upb.c
+++ b/ruby/ext/google/protobuf_c/ruby-upb.c
@@ -404,7 +404,8 @@ void upb_Status_VAppendErrorFormat(upb_Status* status, const char* fmt,
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #include <stddef.h>
 
@@ -2612,6 +2613,7 @@ static upb_MessageValue jsondec_bool(jsondec* d, const upb_FieldDef* f) {
 /* Composite types (array/message/map) ****************************************/
 
 static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Array* arr = upb_Message_Mutable(msg, f, d->arena).array;
 
   jsondec_arrstart(d);
@@ -2625,6 +2627,7 @@ static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 }
 
 static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Map* map = upb_Message_Mutable(msg, f, d->arena).map;
   const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
   const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumber(entry, 1);
@@ -2646,6 +2649,7 @@ static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 
 static void jsondec_tomsg(jsondec* d, upb_Message* msg,
                           const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (upb_MessageDef_WellKnownType(m) == kUpb_WellKnown_Unspecified) {
     jsondec_object(d, msg, m);
   } else {
@@ -2666,6 +2670,7 @@ static upb_MessageValue jsondec_msg(jsondec* d, const upb_FieldDef* f) {
 
 static void jsondec_field(jsondec* d, upb_Message* msg,
                           const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView name;
   const upb_FieldDef* f;
   const upb_FieldDef* preserved;
@@ -2731,6 +2736,7 @@ static void jsondec_field(jsondec* d, upb_Message* msg,
 
 static void jsondec_object(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   jsondec_objstart(d);
   while (jsondec_objnext(d)) {
     jsondec_field(d, msg, m);
@@ -2831,6 +2837,7 @@ static int64_t jsondec_unixtime(int y, int m, int d, int h, int min, int s) {
 
 static void jsondec_timestamp(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue seconds;
   upb_MessageValue nanos;
   upb_StringView str = jsondec_string(d);
@@ -2896,6 +2903,7 @@ malformed:
 
 static void jsondec_duration(jsondec* d, upb_Message* msg,
                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue seconds;
   upb_MessageValue nanos;
   upb_StringView str = jsondec_string(d);
@@ -2928,6 +2936,7 @@ static void jsondec_duration(jsondec* d, upb_Message* msg,
 
 static void jsondec_listvalue(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* value_m = upb_FieldDef_MessageSubDef(values_f);
   const upb_MiniTable* value_layout = upb_MessageDef_MiniTable(value_m);
@@ -2946,6 +2955,7 @@ static void jsondec_listvalue(jsondec* d, upb_Message* msg,
 
 static void jsondec_struct(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* entry_m = upb_FieldDef_MessageSubDef(fields_f);
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(entry_m, 2);
@@ -2968,6 +2978,7 @@ static void jsondec_struct(jsondec* d, upb_Message* msg,
 
 static void jsondec_wellknownvalue(jsondec* d, upb_Message* msg,
                                    const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue val;
   const upb_FieldDef* f;
   upb_Message* submsg;
@@ -3056,6 +3067,7 @@ static upb_StringView jsondec_mask(jsondec* d, const char* buf,
 
 static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   /* repeated string paths = 1; */
   const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_Array* arr = upb_Message_Mutable(msg, paths_f, d->arena).array;
@@ -3079,6 +3091,7 @@ static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
 
 static void jsondec_anyfield(jsondec* d, upb_Message* msg,
                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (upb_MessageDef_WellKnownType(m) == kUpb_WellKnown_Unspecified) {
     /* For regular types: {"@type": "[user type]", "f1": <V1>, "f2": <V2>}
      * where f1, f2, etc. are the normal fields of this type. */
@@ -3097,6 +3110,7 @@ static void jsondec_anyfield(jsondec* d, upb_Message* msg,
 
 static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
                                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* type_url_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* type_m;
   upb_StringView type_url = jsondec_string(d);
@@ -3126,6 +3140,7 @@ static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
 }
 
 static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   /* string type_url = 1;
    * bytes value = 2; */
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 2);
@@ -3194,6 +3209,7 @@ static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
 
 static void jsondec_wrapper(jsondec* d, upb_Message* msg,
                             const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_JsonMessageValue val = jsondec_value(d, value_f);
   UPB_ASSUME(val.ignore == false);  // Wrapper cannot be an enum.
@@ -3202,6 +3218,7 @@ static void jsondec_wrapper(jsondec* d, upb_Message* msg,
 
 static void jsondec_wellknown(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   switch (upb_MessageDef_WellKnownType(m)) {
     case kUpb_WellKnown_Any:
       jsondec_any(d, msg, m);
@@ -3242,6 +3259,7 @@ static void jsondec_wellknown(jsondec* d, upb_Message* msg,
 
 static bool upb_JsonDecoder_Decode(jsondec* const d, upb_Message* const msg,
                                    const upb_MessageDef* const m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (UPB_SETJMP(d->err)) return false;
 
   jsondec_tomsg(d, msg, m);
@@ -4630,10 +4648,8 @@ bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* m,
                              const upb_MiniTableField* f,
                              upb_Message* map_entry_message, upb_Arena* arena) {
   UPB_ASSERT(!upb_Message_IsFrozen(map_entry_message));
-
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_mini_table = upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  const upb_MiniTable* map_entry_mini_table =
+      upb_MiniTable_MapEntrySubMessage(m, f);
   UPB_ASSERT(map_entry_mini_table);
   const upb_MiniTableField* map_entry_key_field =
       upb_MiniTable_MapKey(map_entry_mini_table);
@@ -5536,9 +5552,9 @@ static upb_Map* upb_Message_Map_DeepClone(const upb_Map* map,
                                           const upb_MiniTableField* f,
                                           upb_Message* clone,
                                           upb_Arena* arena) {
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_table = upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  UPB_ASSERT(!upb_Message_IsFrozen(clone));
+  const upb_MiniTable* map_entry_table =
+      upb_MiniTable_MapEntrySubMessage(mini_table, f);
   UPB_ASSERT(map_entry_table);
 
   const upb_MiniTableField* key_field = upb_MiniTable_MapKey(map_entry_table);
@@ -5580,6 +5596,7 @@ static bool upb_Message_Array_DeepClone(const upb_Array* array,
                                         const upb_MiniTable* mini_table,
                                         const upb_MiniTableField* field,
                                         upb_Message* clone, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(clone));
   UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
   upb_Array* cloned_array = upb_Array_DeepClone(
       array, upb_MiniTableField_CType(field),
@@ -5605,6 +5622,7 @@ static bool upb_Clone_ExtensionValue(
 upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
                                const upb_MiniTable* mini_table,
                                upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   upb_StringView empty_string = upb_StringView_FromDataAndSize(NULL, 0);
   // Only copy message area skipping upb_Message_Internal.
   memcpy(dst + 1, src + 1, mini_table->UPB_PRIVATE(size) - sizeof(upb_Message));
@@ -5631,10 +5649,10 @@ upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
             if (dst_sub_message == NULL) {
               return NULL;
             }
-            _upb_Message_SetTaggedMessagePtr(
-                dst, mini_table, field,
-                UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(dst_sub_message,
-                                                        is_empty));
+            UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
+            (dst, field,
+             UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(dst_sub_message,
+                                                     is_empty));
           }
         } break;
         case kUpb_CType_String:
@@ -5711,6 +5729,7 @@ upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
 
 bool upb_Message_DeepCopy(upb_Message* dst, const upb_Message* src,
                           const upb_MiniTable* mini_table, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   upb_Message_Clear(dst, mini_table);
   return _upb_Message_Copy(dst, src, mini_table, arena) != NULL;
 }
@@ -5727,6 +5746,7 @@ upb_Message* upb_Message_DeepClone(const upb_Message* msg,
 // Performs a shallow copy. TODO: Extend to handle unknown fields.
 void upb_Message_ShallowCopy(upb_Message* dst, const upb_Message* src,
                              const upb_MiniTable* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   memcpy(dst, src, m->UPB_PRIVATE(size));
 }
 
@@ -6777,12 +6797,12 @@ bool upb_MiniTable_SetSubMessage(upb_MiniTable* table,
       return false;
   }
 
-  upb_MiniTableSub* table_sub =
-      (void*)&table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)];
+  int idx = field->UPB_PRIVATE(submsg_index);
+  upb_MiniTableSub* table_subs = (void*)table->UPB_PRIVATE(subs);
   // TODO: Add this assert back once YouTube is updated to not call
   // this function repeatedly.
   // UPB_ASSERT(UPB_PRIVATE(_upb_MiniTable_IsEmpty)(table_sub->submsg));
-  *table_sub = upb_MiniTableSub_FromMessage(sub);
+  table_subs[idx] = upb_MiniTableSub_FromMessage(sub);
   return true;
 }
 
@@ -9347,6 +9367,7 @@ UPB_FORCEINLINE
 void* fastdecode_getfield(upb_Decoder* d, const char* ptr, upb_Message* msg,
                           uint64_t* data, uint64_t* hasbits,
                           fastdecode_arr* farr, int valbytes, upb_card card) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   switch (card) {
     case CARD_s: {
       uint8_t hasbit_index = *data >> 24;
@@ -9722,6 +9743,7 @@ UPB_NOINLINE
 static const char* fastdecode_verifyutf8(upb_Decoder* d, const char* ptr,
                                          upb_Message* msg, intptr_t table,
                                          uint64_t hasbits, uint64_t data) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView* dst = (upb_StringView*)data;
   if (!_upb_Decoder_VerifyUtf8Inline(dst->data, dst->size)) {
     _upb_FastDecoder_ErrorJmp(d, kUpb_DecodeStatus_BadUtf8);
@@ -9767,6 +9789,7 @@ UPB_NOINLINE
 static const char* fastdecode_longstring_noutf8(
     struct upb_Decoder* d, const char* ptr, upb_Message* msg, intptr_t table,
     uint64_t hasbits, uint64_t data) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView* dst = (upb_StringView*)data;
   FASTDECODE_LONGSTRING(d, ptr, msg, table, hasbits, dst, false);
 }
@@ -11467,6 +11490,7 @@ const upb_Extension* UPB_PRIVATE(_upb_Message_Getexts)(
 
 upb_Extension* UPB_PRIVATE(_upb_Message_GetOrCreateExtension)(
     struct upb_Message* msg, const upb_MiniTableExtension* e, upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Extension* ext = (upb_Extension*)UPB_PRIVATE(_upb_Message_Getext)(msg, e);
   if (ext) return ext;
   if (!UPB_PRIVATE(_upb_Message_Realloc)(msg, sizeof(upb_Extension), a))
@@ -11492,6 +11516,7 @@ const double kUpb_NaN = NAN;
 
 bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
                                        upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const size_t overhead = sizeof(upb_Message_Internal);
 
   upb_Message_Internal* in = UPB_PRIVATE(_upb_Message_GetInternal)(msg);
@@ -11528,21 +11553,19 @@ bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
 }
 
 #if UPB_TRACING_ENABLED
-static void (*_new_message_trace_handler)(const upb_MiniTable*,
-                                          const upb_Arena*);
+static void (*_message_trace_handler)(const upb_MiniTable*, const upb_Arena*);
 
-void UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(
-    void (*new_message_trace_handler)(const upb_MiniTable*, const upb_Arena*)) {
-  _new_message_trace_handler = new_message_trace_handler;
+void upb_Message_LogNewMessage(const upb_MiniTable* m, const upb_Arena* arena) {
+  if (_message_trace_handler) {
+    _message_trace_handler(m, arena);
+  }
 }
 
-void UPB_PRIVATE(upb_Message_LogNewMessage)(const upb_MiniTable* mini_table,
-                                            const upb_Arena* arena) {
-  if (_new_message_trace_handler) {
-    _new_message_trace_handler(mini_table, arena);
-  }
+void upb_Message_SetNewMessageTraceHandler(void (*handler)(const upb_MiniTable*,
+                                                           const upb_Arena*)) {
+  _message_trace_handler = handler;
 }
-#endif
+#endif  // UPB_TRACING_ENABLED
 
 
 const char _kUpb_ToBase92[] = {
@@ -13166,11 +13189,11 @@ upb_MessageValue upb_FieldDef_Default(const upb_FieldDef* f) {
 }
 
 const upb_MessageDef* upb_FieldDef_MessageSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_CType(f) == kUpb_CType_Message ? f->sub.msgdef : NULL;
+  return upb_FieldDef_IsSubMessage(f) ? f->sub.msgdef : NULL;
 }
 
 const upb_EnumDef* upb_FieldDef_EnumSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_CType(f) == kUpb_CType_Enum ? f->sub.enumdef : NULL;
+  return upb_FieldDef_IsEnum(f) ? f->sub.enumdef : NULL;
 }
 
 const upb_MiniTableField* upb_FieldDef_MiniTable(const upb_FieldDef* f) {
@@ -13268,8 +13291,11 @@ bool upb_FieldDef_HasDefault(const upb_FieldDef* f) { return f->has_default; }
 bool upb_FieldDef_HasPresence(const upb_FieldDef* f) { return f->has_presence; }
 
 bool upb_FieldDef_HasSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_IsSubMessage(f) ||
-         upb_FieldDef_CType(f) == kUpb_CType_Enum;
+  return upb_FieldDef_IsSubMessage(f) || upb_FieldDef_IsEnum(f);
+}
+
+bool upb_FieldDef_IsEnum(const upb_FieldDef* f) {
+  return upb_FieldDef_CType(f) == kUpb_CType_Enum;
 }
 
 bool upb_FieldDef_IsMap(const upb_FieldDef* f) {
@@ -14894,6 +14920,7 @@ upb_MessageValue upb_Message_GetFieldByDef(const upb_Message* msg,
 upb_MutableMessageValue upb_Message_Mutable(upb_Message* msg,
                                             const upb_FieldDef* f,
                                             upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   UPB_ASSERT(upb_FieldDef_IsSubMessage(f) || upb_FieldDef_IsRepeated(f));
   if (upb_FieldDef_HasPresence(f) && !upb_Message_HasFieldByDef(msg, f)) {
     // We need to skip the upb_Message_GetFieldByDef() call in this case.
@@ -14932,6 +14959,7 @@ make:
 
 bool upb_Message_SetFieldByDef(upb_Message* msg, const upb_FieldDef* f,
                                upb_MessageValue val, upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_MiniTableField* m_f = upb_FieldDef_MiniTable(f);
 
   if (upb_MiniTableField_IsExtension(m_f)) {
@@ -14944,6 +14972,7 @@ bool upb_Message_SetFieldByDef(upb_Message* msg, const upb_FieldDef* f,
 }
 
 void upb_Message_ClearFieldByDef(upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_MiniTableField* m_f = upb_FieldDef_MiniTable(f);
 
   if (upb_MiniTableField_IsExtension(m_f)) {
@@ -14954,6 +14983,7 @@ void upb_Message_ClearFieldByDef(upb_Message* msg, const upb_FieldDef* f) {
 }
 
 void upb_Message_ClearByDef(upb_Message* msg, const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Message_Clear(msg, upb_MessageDef_MiniTable(m));
 }
 
@@ -15015,6 +15045,7 @@ bool upb_Message_Next(const upb_Message* msg, const upb_MessageDef* m,
 
 bool _upb_Message_DiscardUnknown(upb_Message* msg, const upb_MessageDef* m,
                                  int depth) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   size_t iter = kUpb_Message_Begin;
   const upb_FieldDef* f;
   upb_MessageValue val;
diff --git a/ruby/ext/google/protobuf_c/ruby-upb.h b/ruby/ext/google/protobuf_c/ruby-upb.h
index f88cd1ff86..3d9024c6a9 100755
--- a/ruby/ext/google/protobuf_c/ruby-upb.h
+++ b/ruby/ext/google/protobuf_c/ruby-upb.h
@@ -415,113 +415,6 @@ void upb_Status_VAppendErrorFormat(upb_Status* status, const char* fmt,
 #ifndef UPB_MESSAGE_ACCESSORS_H_
 #define UPB_MESSAGE_ACCESSORS_H_
 
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-
-#ifndef UPB_BASE_DESCRIPTOR_CONSTANTS_H_
-#define UPB_BASE_DESCRIPTOR_CONSTANTS_H_
-
-// Must be last.
-
-// The types a field can have. Note that this list is not identical to the
-// types defined in descriptor.proto, which gives INT32 and SINT32 separate
-// types (we distinguish the two with the "integer encoding" enum below).
-// This enum is an internal convenience only and has no meaning outside of upb.
-typedef enum {
-  kUpb_CType_Bool = 1,
-  kUpb_CType_Float = 2,
-  kUpb_CType_Int32 = 3,
-  kUpb_CType_UInt32 = 4,
-  kUpb_CType_Enum = 5,  // Enum values are int32. TODO: rename
-  kUpb_CType_Message = 6,
-  kUpb_CType_Double = 7,
-  kUpb_CType_Int64 = 8,
-  kUpb_CType_UInt64 = 9,
-  kUpb_CType_String = 10,
-  kUpb_CType_Bytes = 11
-} upb_CType;
-
-// The repeated-ness of each field; this matches descriptor.proto.
-typedef enum {
-  kUpb_Label_Optional = 1,
-  kUpb_Label_Required = 2,
-  kUpb_Label_Repeated = 3
-} upb_Label;
-
-// Descriptor types, as defined in descriptor.proto.
-typedef enum {
-  kUpb_FieldType_Double = 1,
-  kUpb_FieldType_Float = 2,
-  kUpb_FieldType_Int64 = 3,
-  kUpb_FieldType_UInt64 = 4,
-  kUpb_FieldType_Int32 = 5,
-  kUpb_FieldType_Fixed64 = 6,
-  kUpb_FieldType_Fixed32 = 7,
-  kUpb_FieldType_Bool = 8,
-  kUpb_FieldType_String = 9,
-  kUpb_FieldType_Group = 10,
-  kUpb_FieldType_Message = 11,
-  kUpb_FieldType_Bytes = 12,
-  kUpb_FieldType_UInt32 = 13,
-  kUpb_FieldType_Enum = 14,
-  kUpb_FieldType_SFixed32 = 15,
-  kUpb_FieldType_SFixed64 = 16,
-  kUpb_FieldType_SInt32 = 17,
-  kUpb_FieldType_SInt64 = 18,
-} upb_FieldType;
-
-#define kUpb_FieldType_SizeOf 19
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-// Convert from upb_FieldType to upb_CType
-UPB_INLINE upb_CType upb_FieldType_CType(upb_FieldType field_type) {
-  static const upb_CType c_type[] = {
-      kUpb_CType_Double,   // kUpb_FieldType_Double
-      kUpb_CType_Float,    // kUpb_FieldType_Float
-      kUpb_CType_Int64,    // kUpb_FieldType_Int64
-      kUpb_CType_UInt64,   // kUpb_FieldType_UInt64
-      kUpb_CType_Int32,    // kUpb_FieldType_Int32
-      kUpb_CType_UInt64,   // kUpb_FieldType_Fixed64
-      kUpb_CType_UInt32,   // kUpb_FieldType_Fixed32
-      kUpb_CType_Bool,     // kUpb_FieldType_Bool
-      kUpb_CType_String,   // kUpb_FieldType_String
-      kUpb_CType_Message,  // kUpb_FieldType_Group
-      kUpb_CType_Message,  // kUpb_FieldType_Message
-      kUpb_CType_Bytes,    // kUpb_FieldType_Bytes
-      kUpb_CType_UInt32,   // kUpb_FieldType_UInt32
-      kUpb_CType_Enum,     // kUpb_FieldType_Enum
-      kUpb_CType_Int32,    // kUpb_FieldType_SFixed32
-      kUpb_CType_Int64,    // kUpb_FieldType_SFixed64
-      kUpb_CType_Int32,    // kUpb_FieldType_SInt32
-      kUpb_CType_Int64,    // kUpb_FieldType_SInt64
-  };
-
-  // -1 here because the enum is one-based but the table is zero-based.
-  return c_type[field_type - 1];
-}
-
-UPB_INLINE bool upb_FieldType_IsPackable(upb_FieldType field_type) {
-  // clang-format off
-  const unsigned kUnpackableTypes =
-      (1 << kUpb_FieldType_String) |
-      (1 << kUpb_FieldType_Bytes) |
-      (1 << kUpb_FieldType_Message) |
-      (1 << kUpb_FieldType_Group);
-  // clang-format on
-  return (1 << field_type) & ~kUnpackableTypes;
-}
-
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
-
-
-#endif /* UPB_BASE_DESCRIPTOR_CONSTANTS_H_ */
 #ifndef UPB_BASE_STRING_VIEW_H_
 #define UPB_BASE_STRING_VIEW_H_
 
@@ -829,6 +722,109 @@ void upb_Arena_SetTraceHandler(void (*initArenaTraceHandler)(const upb_Arena*,
 #include <stddef.h>
 
 
+#ifndef UPB_BASE_DESCRIPTOR_CONSTANTS_H_
+#define UPB_BASE_DESCRIPTOR_CONSTANTS_H_
+
+// Must be last.
+
+// The types a field can have. Note that this list is not identical to the
+// types defined in descriptor.proto, which gives INT32 and SINT32 separate
+// types (we distinguish the two with the "integer encoding" enum below).
+// This enum is an internal convenience only and has no meaning outside of upb.
+typedef enum {
+  kUpb_CType_Bool = 1,
+  kUpb_CType_Float = 2,
+  kUpb_CType_Int32 = 3,
+  kUpb_CType_UInt32 = 4,
+  kUpb_CType_Enum = 5,  // Enum values are int32. TODO: rename
+  kUpb_CType_Message = 6,
+  kUpb_CType_Double = 7,
+  kUpb_CType_Int64 = 8,
+  kUpb_CType_UInt64 = 9,
+  kUpb_CType_String = 10,
+  kUpb_CType_Bytes = 11
+} upb_CType;
+
+// The repeated-ness of each field; this matches descriptor.proto.
+typedef enum {
+  kUpb_Label_Optional = 1,
+  kUpb_Label_Required = 2,
+  kUpb_Label_Repeated = 3
+} upb_Label;
+
+// Descriptor types, as defined in descriptor.proto.
+typedef enum {
+  kUpb_FieldType_Double = 1,
+  kUpb_FieldType_Float = 2,
+  kUpb_FieldType_Int64 = 3,
+  kUpb_FieldType_UInt64 = 4,
+  kUpb_FieldType_Int32 = 5,
+  kUpb_FieldType_Fixed64 = 6,
+  kUpb_FieldType_Fixed32 = 7,
+  kUpb_FieldType_Bool = 8,
+  kUpb_FieldType_String = 9,
+  kUpb_FieldType_Group = 10,
+  kUpb_FieldType_Message = 11,
+  kUpb_FieldType_Bytes = 12,
+  kUpb_FieldType_UInt32 = 13,
+  kUpb_FieldType_Enum = 14,
+  kUpb_FieldType_SFixed32 = 15,
+  kUpb_FieldType_SFixed64 = 16,
+  kUpb_FieldType_SInt32 = 17,
+  kUpb_FieldType_SInt64 = 18,
+} upb_FieldType;
+
+#define kUpb_FieldType_SizeOf 19
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Convert from upb_FieldType to upb_CType
+UPB_INLINE upb_CType upb_FieldType_CType(upb_FieldType field_type) {
+  static const upb_CType c_type[] = {
+      kUpb_CType_Double,   // kUpb_FieldType_Double
+      kUpb_CType_Float,    // kUpb_FieldType_Float
+      kUpb_CType_Int64,    // kUpb_FieldType_Int64
+      kUpb_CType_UInt64,   // kUpb_FieldType_UInt64
+      kUpb_CType_Int32,    // kUpb_FieldType_Int32
+      kUpb_CType_UInt64,   // kUpb_FieldType_Fixed64
+      kUpb_CType_UInt32,   // kUpb_FieldType_Fixed32
+      kUpb_CType_Bool,     // kUpb_FieldType_Bool
+      kUpb_CType_String,   // kUpb_FieldType_String
+      kUpb_CType_Message,  // kUpb_FieldType_Group
+      kUpb_CType_Message,  // kUpb_FieldType_Message
+      kUpb_CType_Bytes,    // kUpb_FieldType_Bytes
+      kUpb_CType_UInt32,   // kUpb_FieldType_UInt32
+      kUpb_CType_Enum,     // kUpb_FieldType_Enum
+      kUpb_CType_Int32,    // kUpb_FieldType_SFixed32
+      kUpb_CType_Int64,    // kUpb_FieldType_SFixed64
+      kUpb_CType_Int32,    // kUpb_FieldType_SInt32
+      kUpb_CType_Int64,    // kUpb_FieldType_SInt64
+  };
+
+  // -1 here because the enum is one-based but the table is zero-based.
+  return c_type[field_type - 1];
+}
+
+UPB_INLINE bool upb_FieldType_IsPackable(upb_FieldType field_type) {
+  // clang-format off
+  const unsigned kUnpackableTypes =
+      (1 << kUpb_FieldType_String) |
+      (1 << kUpb_FieldType_Bytes) |
+      (1 << kUpb_FieldType_Message) |
+      (1 << kUpb_FieldType_Group);
+  // clang-format on
+  return (1 << field_type) & ~kUnpackableTypes;
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+
+#endif /* UPB_BASE_DESCRIPTOR_CONSTANTS_H_ */
+
 #ifndef UPB_MESSAGE_INTERNAL_ARRAY_H_
 #define UPB_MESSAGE_INTERNAL_ARRAY_H_
 
@@ -1411,6 +1407,7 @@ UPB_API_INLINE bool upb_MiniTableEnum_CheckValue(const upb_MiniTableEnum* e,
 #ifndef UPB_MINI_TABLE_INTERNAL_MESSAGE_H_
 #define UPB_MINI_TABLE_INTERNAL_MESSAGE_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
 
@@ -1542,34 +1539,44 @@ UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_GetFieldByIndex(
   return &m->UPB_ONLYBITS(fields)[i];
 }
 
-UPB_INLINE const union upb_MiniTableSub* UPB_PRIVATE(
+UPB_INLINE const union upb_MiniTableSub UPB_PRIVATE(
     _upb_MiniTable_GetSubByIndex)(const struct upb_MiniTable* m, uint32_t i) {
-  return &m->UPB_PRIVATE(subs)[i];
+  return m->UPB_PRIVATE(subs)[i];
+}
+
+UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_SubMessage(
+    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
+  if (upb_MiniTableField_CType(f) != kUpb_CType_Message) {
+    return NULL;
+  }
+  return m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)].UPB_PRIVATE(submsg);
 }
 
 UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_GetSubMessageTable(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  UPB_ASSERT(upb_MiniTableField_CType(f) == kUpb_CType_Message);
-  const struct upb_MiniTable* ret = upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  const struct upb_MiniTable* ret = upb_MiniTable_SubMessage(m, f);
   UPB_ASSUME(ret);
   return UPB_PRIVATE(_upb_MiniTable_IsEmpty)(ret) ? NULL : ret;
 }
 
-UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_SubMessage(
+UPB_API_INLINE bool upb_MiniTable_FieldIsLinked(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  if (upb_MiniTableField_CType(f) != kUpb_CType_Message) {
-    return NULL;
-  }
-  return upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  return upb_MiniTable_GetSubMessageTable(m, f) != NULL;
+}
+
+UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_MapEntrySubMessage(
+    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
+  UPB_ASSERT(upb_MiniTable_FieldIsLinked(m, f));  // Map entries must be linked.
+  UPB_ASSERT(upb_MiniTableField_IsMap(f));        // Function precondition.
+  return upb_MiniTable_SubMessage(m, f);
 }
 
 UPB_API_INLINE const struct upb_MiniTableEnum* upb_MiniTable_GetSubEnumTable(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
   UPB_ASSERT(upb_MiniTableField_CType(f) == kUpb_CType_Enum);
-  return upb_MiniTableSub_Enum(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  return m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)].UPB_PRIVATE(
+      subenum);
 }
 
 UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_MapKey(
@@ -1588,11 +1595,6 @@ UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_MapValue(
   return f;
 }
 
-UPB_API_INLINE bool upb_MiniTable_FieldIsLinked(
-    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  return upb_MiniTable_GetSubMessageTable(m, f) != NULL;
-}
-
 // Computes a bitmask in which the |m->required_count| lowest bits are set.
 //
 // Sample output:
@@ -1647,10 +1649,20 @@ UPB_API_INLINE int upb_MiniTable_FieldCount(const upb_MiniTable* m);
 UPB_API_INLINE const upb_MiniTable* upb_MiniTable_GetSubMessageTable(
     const upb_MiniTable* m, const upb_MiniTableField* f);
 
-// Returns the MiniTable for a message field if it is a submessage.
+// Returns the MiniTable for a message field if it is a submessage, otherwise
+// returns NULL.
+//
+// WARNING: if dynamic tree shaking is in use, the return value may be the
+// "empty", zero-field placeholder message instead of the real message type.
+// If the message is later linked, this function will begin returning the real
+// message type.
 UPB_API_INLINE const upb_MiniTable* upb_MiniTable_SubMessage(
     const upb_MiniTable* m, const upb_MiniTableField* f);
 
+// Returns the MiniTable for a map field.  The given field must refer to a map.
+UPB_API_INLINE const upb_MiniTable* upb_MiniTable_MapEntrySubMessage(
+    const upb_MiniTable* m, const upb_MiniTableField* f);
+
 // Returns the MiniTableEnum for a message field, NULL if the field is unlinked.
 UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTable_GetSubEnumTable(
     const upb_MiniTable* m, const upb_MiniTableField* f);
@@ -1831,6 +1843,7 @@ UPB_INLINE uint64_t upb_BigEndian64(uint64_t val) {
 #ifndef UPB_MINI_TABLE_INTERNAL_EXTENSION_H_
 #define UPB_MINI_TABLE_INTERNAL_EXTENSION_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
 
@@ -1860,6 +1873,9 @@ upb_MiniTableExtension_Number(const struct upb_MiniTableExtension* e) {
 
 UPB_API_INLINE const struct upb_MiniTable* upb_MiniTableExtension_GetSubMessage(
     const struct upb_MiniTableExtension* e) {
+  if (upb_MiniTableExtension_CType(e) != kUpb_CType_Message) {
+    return NULL;
+  }
   return upb_MiniTableSub_Message(e->UPB_PRIVATE(sub));
 }
 
@@ -1868,6 +1884,11 @@ UPB_API_INLINE void upb_MiniTableExtension_SetSubMessage(
   e->UPB_PRIVATE(sub).UPB_PRIVATE(submsg) = m;
 }
 
+UPB_INLINE upb_FieldRep UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(
+    const struct upb_MiniTableExtension* e) {
+  return UPB_PRIVATE(_upb_MiniTableField_GetRep)(&e->UPB_PRIVATE(field));
+}
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
@@ -2456,18 +2477,19 @@ typedef struct upb_Message_Internal {
 } upb_Message_Internal;
 
 #ifdef UPB_TRACING_ENABLED
-void UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(
-    void (*newMessageTraceHandler)(const upb_MiniTable*, const upb_Arena*));
-void UPB_PRIVATE(upb_Message_LogNewMessage)(const upb_MiniTable* mini_table,
-                                            const upb_Arena* arena);
-#endif
+UPB_API void upb_Message_LogNewMessage(const upb_MiniTable* m,
+                                       const upb_Arena* arena);
+UPB_API void upb_Message_SetNewMessageTraceHandler(
+    void (*handler)(const upb_MiniTable*, const upb_Arena*));
+#endif  // UPB_TRACING_ENABLED
 
 // Inline version upb_Message_New(), for internal use.
 UPB_INLINE struct upb_Message* _upb_Message_New(const upb_MiniTable* m,
                                                 upb_Arena* a) {
 #ifdef UPB_TRACING_ENABLED
-  UPB_PRIVATE(upb_Message_LogNewMessage)(m, a);
-#endif
+  upb_Message_LogNewMessage(m, a);
+#endif  // UPB_TRACING_ENABLED
+
   const int size = m->UPB_PRIVATE(size);
   struct upb_Message* msg = (struct upb_Message*)upb_Arena_Malloc(a, size);
   if (UPB_UNLIKELY(!msg)) return NULL;
@@ -2677,6 +2699,12 @@ UPB_INLINE bool UPB_PRIVATE(_upb_Message_ClearOneofCase)(
   return true;
 }
 
+UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
+    const struct upb_Message* message, const upb_MiniTableField* oneof_field) {
+  UPB_ASSUME(upb_MiniTableField_IsInOneof(oneof_field));
+  return UPB_PRIVATE(_upb_Message_GetOneofCase)(message, oneof_field);
+}
+
 // LINT.ThenChange(GoogleInternalName2)
 
 // Returns false if the message is missing any of its required fields.
@@ -2775,7 +2803,6 @@ UPB_INLINE bool UPB_PRIVATE(_upb_MiniTableField_DataIsZero)(
 //                                       const upb_MiniTableField* field,
 //                                       bool value, upb_Arena* a) {
 //     UPB_ASSUME(field->UPB_PRIVATE(descriptortype) == kUpb_FieldType_Bool);
-//     UPB_ASSUME(upb_MiniTableField_IsScalar(field));
 //     UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
 //                kUpb_FieldRep_1Byte);
 //     upb_Message_SetField(msg, field, &value, a);
@@ -2836,13 +2863,31 @@ UPB_INLINE void _upb_Message_GetExtensionField(
   }
 }
 
-UPB_API_INLINE void upb_Message_SetBaseField(struct upb_Message* msg,
-                                             const upb_MiniTableField* f,
-                                             const void* val) {
-  UPB_ASSERT(!upb_Message_IsFrozen(msg));
-  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
-  UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
-  UPB_PRIVATE(_upb_MiniTableField_DataCopy)
+// NOTE: The default_val is only used for fields that support presence.
+// For repeated/map fields, the resulting upb_Array*/upb_Map* can be NULL if a
+// upb_Array/upb_Map has not been allocated yet. Array/map fields do not have
+// presence, so this is semantically identical to a pointer to an empty
+// array/map, and must be treated the same for all semantic purposes.
+UPB_API_INLINE upb_MessageValue upb_Message_GetField(
+    const struct upb_Message* msg, const upb_MiniTableField* field,
+    upb_MessageValue default_val) {
+  upb_MessageValue ret;
+  if (upb_MiniTableField_IsExtension(field)) {
+    _upb_Message_GetExtensionField(msg, (upb_MiniTableExtension*)field,
+                                   &default_val, &ret);
+  } else {
+    _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
+  }
+  return ret;
+}
+
+UPB_API_INLINE void upb_Message_SetBaseField(struct upb_Message* msg,
+                                             const upb_MiniTableField* f,
+                                             const void* val) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
+  UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
+  UPB_PRIVATE(_upb_MiniTableField_DataCopy)
   (f, UPB_PRIVATE(_upb_Message_MutableDataPtr)(msg, f), val);
 }
 
@@ -2859,6 +2904,516 @@ UPB_API_INLINE bool upb_Message_SetExtension(struct upb_Message* msg,
   return true;
 }
 
+// Sets the value of the given field in the given msg. The return value is true
+// if the operation completed successfully, or false if memory allocation
+// failed.
+UPB_INLINE bool UPB_PRIVATE(_upb_Message_SetField)(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_MessageValue val,
+                                                   upb_Arena* a) {
+  if (upb_MiniTableField_IsExtension(f)) {
+    const upb_MiniTableExtension* ext = (const upb_MiniTableExtension*)f;
+    return upb_Message_SetExtension(msg, ext, &val, a);
+  } else {
+    upb_Message_SetBaseField(msg, f, &val);
+    return true;
+  }
+}
+
+UPB_API_INLINE const upb_Array* upb_Message_GetArray(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* ret;
+  const upb_Array* default_val = NULL;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &ret);
+  return ret;
+}
+
+UPB_API_INLINE bool upb_Message_GetBool(const struct upb_Message* msg,
+                                        const upb_MiniTableField* f,
+                                        bool default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Bool);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_1Byte);
+  upb_MessageValue def;
+  def.bool_val = default_val;
+  return upb_Message_GetField(msg, f, def).bool_val;
+}
+
+UPB_API_INLINE double upb_Message_GetDouble(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            double default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Double);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.double_val = default_val;
+  return upb_Message_GetField(msg, f, def).double_val;
+}
+
+UPB_API_INLINE float upb_Message_GetFloat(const struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          float default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Float);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.float_val = default_val;
+  return upb_Message_GetField(msg, f, def).float_val;
+}
+
+UPB_API_INLINE int32_t upb_Message_GetInt32(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int32_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int32 ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Enum);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.int32_val = default_val;
+  return upb_Message_GetField(msg, f, def).int32_val;
+}
+
+UPB_API_INLINE int64_t upb_Message_GetInt64(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int64_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.int64_val = default_val;
+  return upb_Message_GetField(msg, f, def).int64_val;
+}
+
+UPB_INLINE void UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(
+    const struct upb_Message* msg, const upb_MiniTableField* field) {
+  UPB_UNUSED(msg);
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+#ifndef NDEBUG
+  uintptr_t default_val = 0;
+  uintptr_t tagged;
+  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
+  UPB_ASSERT(!upb_TaggedMessagePtr_IsEmpty(tagged));
+#endif
+}
+
+UPB_API_INLINE const struct upb_Map* upb_Message_GetMap(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(f);
+  UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(msg, f);
+  struct upb_Map* ret;
+  const struct upb_Map* default_val = NULL;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &ret);
+  return ret;
+}
+
+UPB_API_INLINE uintptr_t upb_Message_GetTaggedMessagePtr(
+    const struct upb_Message* msg, const upb_MiniTableField* f,
+    struct upb_Message* default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  uintptr_t tagged;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &tagged);
+  return tagged;
+}
+
+// For internal use only; users cannot set tagged messages because only the
+// parser and the message copier are allowed to directly create an empty
+// message.
+UPB_INLINE void UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)(
+    struct upb_Message* msg, const upb_MiniTableField* f,
+    uintptr_t sub_message) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  upb_Message_SetBaseField(msg, f, &sub_message);
+}
+
+UPB_API_INLINE const struct upb_Message* upb_Message_GetMessage(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  uintptr_t tagged = upb_Message_GetTaggedMessagePtr(msg, f, NULL);
+  return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
+}
+
+UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  return (upb_Array*)upb_Message_GetArray(msg, f);
+}
+
+UPB_API_INLINE struct upb_Map* upb_Message_GetMutableMap(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  return (struct upb_Map*)upb_Message_GetMap(msg, f);
+}
+
+UPB_API_INLINE struct upb_Message* upb_Message_GetMutableMessage(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  return (struct upb_Message*)upb_Message_GetMessage(msg, f);
+}
+
+UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
+    struct upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSERT(arena);
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* array = upb_Message_GetMutableArray(msg, f);
+  if (!array) {
+    array = UPB_PRIVATE(_upb_Array_New)(
+        arena, 4, UPB_PRIVATE(_upb_MiniTableField_ElemSizeLg2)(f));
+    // Check again due to: https://godbolt.org/z/7WfaoKG1r
+    UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+    upb_MessageValue val;
+    val.array_val = array;
+    UPB_PRIVATE(_upb_Message_SetField)(msg, f, val, arena);
+  }
+  return array;
+}
+
+UPB_INLINE struct upb_Map* _upb_Message_GetOrCreateMutableMap(
+    struct upb_Message* msg, const upb_MiniTableField* field, size_t key_size,
+    size_t val_size, upb_Arena* arena) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+  UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(msg, field);
+  struct upb_Map* map = NULL;
+  struct upb_Map* default_map_value = NULL;
+  _upb_Message_GetNonExtensionField(msg, field, &default_map_value, &map);
+  if (!map) {
+    map = _upb_Map_New(arena, key_size, val_size);
+    // Check again due to: https://godbolt.org/z/7WfaoKG1r
+    UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+    upb_Message_SetBaseField(msg, field, &map);
+  }
+  return map;
+}
+
+UPB_API_INLINE struct upb_Map* upb_Message_GetOrCreateMutableMap(
+    struct upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  const upb_MiniTableField* map_entry_key_field =
+      &map_entry_mini_table->UPB_ONLYBITS(fields)[0];
+  const upb_MiniTableField* map_entry_value_field =
+      &map_entry_mini_table->UPB_ONLYBITS(fields)[1];
+  return _upb_Message_GetOrCreateMutableMap(
+      msg, f, _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_key_field)),
+      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_value_field)),
+      arena);
+}
+
+UPB_API_INLINE struct upb_Message* upb_Message_GetOrCreateMutableMessage(
+    struct upb_Message* msg, const upb_MiniTable* mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSERT(arena);
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
+  struct upb_Message* sub_message =
+      *UPB_PTR_AT(msg, f->UPB_ONLYBITS(offset), struct upb_Message*);
+  if (!sub_message) {
+    const upb_MiniTable* sub_mini_table =
+        upb_MiniTable_SubMessage(mini_table, f);
+    UPB_ASSERT(sub_mini_table);
+    sub_message = _upb_Message_New(sub_mini_table, arena);
+    *UPB_PTR_AT(msg, f->UPB_ONLYBITS(offset), struct upb_Message*) =
+        sub_message;
+    UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
+  }
+  return sub_message;
+}
+
+UPB_API_INLINE upb_StringView
+upb_Message_GetString(const struct upb_Message* msg,
+                      const upb_MiniTableField* f, upb_StringView default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_String ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Bytes);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             kUpb_FieldRep_StringView);
+
+  upb_MessageValue def;
+  def.str_val = default_val;
+  return upb_Message_GetField(msg, f, def).str_val;
+}
+
+UPB_API_INLINE uint32_t upb_Message_GetUInt32(const struct upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint32_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt32);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.uint32_val = default_val;
+  return upb_Message_GetField(msg, f, def).uint32_val;
+}
+
+UPB_API_INLINE uint64_t upb_Message_GetUInt64(const struct upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint64_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.uint64_val = default_val;
+  return upb_Message_GetField(msg, f, def).uint64_val;
+}
+
+// BaseField Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE void upb_Message_SetBaseFieldBool(struct upb_Message* msg,
+                                                 const upb_MiniTableField* f,
+                                                 bool value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Bool);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_1Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldDouble(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   double value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Double);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldFloat(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  float value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Float);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldInt32(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int32_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int32 ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Enum);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldInt64(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int64_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldString(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_StringView value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_String ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Bytes);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             kUpb_FieldRep_StringView);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt32(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint32_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt32);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt64(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint64_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetClosedEnum(struct upb_Message* msg,
+                                              const upb_MiniTable* m,
+                                              const upb_MiniTableField* f,
+                                              int32_t value) {
+  UPB_ASSERT(upb_MiniTableField_IsClosedEnum(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  UPB_ASSERT(
+      upb_MiniTableEnum_CheckValue(upb_MiniTable_GetSubEnumTable(m, f), value));
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+// Extension Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetExtensionBool(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, bool value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Bool);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_1Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionDouble(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, double value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Double);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionFloat(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, float value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Float);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int32_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Int32 ||
+             upb_MiniTableExtension_CType(e) == kUpb_CType_Enum);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int64_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Int64);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionString(
+    struct upb_Message* msg, const upb_MiniTableExtension* e,
+    upb_StringView value, upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_String ||
+             upb_MiniTableExtension_CType(e) == kUpb_CType_Bytes);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_StringView);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint32_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_UInt32);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint64_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_UInt64);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+// Universal Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetBool(struct upb_Message* msg,
+                                        const upb_MiniTableField* f, bool value,
+                                        upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionBool(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldBool(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetDouble(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          double value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionDouble(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldDouble(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetFloat(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         float value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionFloat(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldFloat(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt32(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int32_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionInt32(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldInt32(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt64(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int64_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionInt64(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldInt64(msg, f, value), true);
+}
+
+// Sets the value of a message-typed field. The mini_tables of `msg` and
+// `value` must have been linked for this to work correctly.
+UPB_API_INLINE void upb_Message_SetMessage(struct upb_Message* msg,
+                                           const upb_MiniTableField* f,
+                                           struct upb_Message* value) {
+  UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
+  (msg, f, UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(value, false));
+}
+
+// Sets the value of a `string` or `bytes` field. The bytes of the value are not
+// copied, so it is the caller's responsibility to ensure that they remain valid
+// for the lifetime of `msg`. That might be done by copying them into the given
+// arena, or by fusing that arena with the arena the bytes live in, for example.
+UPB_API_INLINE bool upb_Message_SetString(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          upb_StringView value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionString(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldString(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt32(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint32_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionUInt32(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldUInt32(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt64(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint64_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionUInt64(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldUInt64(msg, f, value), true);
+}
+
 UPB_API_INLINE void upb_Message_Clear(struct upb_Message* msg,
                                       const upb_MiniTable* m) {
   UPB_ASSERT(!upb_Message_IsFrozen(msg));
@@ -2900,33 +3455,30 @@ UPB_API_INLINE void upb_Message_ClearExtension(
   }
 }
 
-UPB_INLINE void _upb_Message_AssertMapIsUntagged(
-    const struct upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_UNUSED(msg);
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-#ifndef NDEBUG
-  uintptr_t default_val = 0;
-  uintptr_t tagged;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
-  UPB_ASSERT(!upb_TaggedMessagePtr_IsEmpty(tagged));
-#endif
+UPB_API_INLINE void upb_Message_ClearOneof(struct upb_Message* msg,
+                                           const upb_MiniTable* m,
+                                           const upb_MiniTableField* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+  uint32_t field_number = upb_Message_WhichOneofFieldNumber(msg, f);
+  if (field_number == 0) {
+    // No field in the oneof is set.
+    return;
+  }
+
+  const upb_MiniTableField* field =
+      upb_MiniTable_FindFieldByNumber(m, field_number);
+  upb_Message_ClearBaseField(msg, field);
 }
 
-UPB_INLINE struct upb_Map* _upb_Message_GetOrCreateMutableMap(
-    struct upb_Message* msg, const upb_MiniTableField* field, size_t key_size,
-    size_t val_size, upb_Arena* arena) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-  _upb_Message_AssertMapIsUntagged(msg, field);
-  struct upb_Map* map = NULL;
-  struct upb_Map* default_map_value = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_map_value, &map);
-  if (!map) {
-    map = _upb_Map_New(arena, key_size, val_size);
-    // Check again due to: https://godbolt.org/z/7WfaoKG1r
-    UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-    upb_Message_SetBaseField(msg, field, &map);
+UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
+    struct upb_Message* msg, const upb_MiniTableField* f, size_t size,
+    upb_Arena* arena) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* arr = upb_Message_GetOrCreateMutableArray(msg, f, arena);
+  if (!arr || !UPB_PRIVATE(_upb_Array_ResizeUninitialized)(arr, size, arena)) {
+    return NULL;
   }
-  return map;
+  return upb_Array_MutableDataPtr(arr);
 }
 
 #ifdef __cplusplus
@@ -3049,12 +3601,6 @@ UPB_API_INLINE bool upb_Map_IsFrozen(const upb_Map* map);
 
 #endif /* UPB_MESSAGE_MAP_H_ */
 
-#ifndef UPB_MINI_TABLE_TAGGED_PTR_H_
-#define UPB_MINI_TABLE_TAGGED_PTR_H_
-
-#include <stdint.h>
-
-
 // Public APIs for message operations that do not depend on the schema.
 //
 // MiniTable-based accessors live in accessors.h.
@@ -3092,16 +3638,12 @@ UPB_API void upb_Message_Freeze(upb_Message* msg, const upb_MiniTable* m);
 UPB_API_INLINE bool upb_Message_IsFrozen(const upb_Message* msg);
 
 #ifdef UPB_TRACING_ENABLED
-UPB_INLINE void upb_Message_SetNewMessageTraceHandler(
-    void (*newMessageTraceHandler)(const upb_MiniTable* mini_table,
-                                   const upb_Arena* arena)) {
-  UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(newMessageTraceHandler);
-}
-UPB_INLINE void upb_Message_LogNewMessage(const upb_MiniTable* mini_table,
-                                          const upb_Arena* arena) {
-  UPB_PRIVATE(upb_Message_LogNewMessage)(mini_table, arena);
-}
-#endif
+UPB_API void upb_Message_LogNewMessage(const upb_MiniTable* m,
+                                       const upb_Arena* arena);
+
+UPB_API void upb_Message_SetNewMessageTraceHandler(
+    void (*handler)(const upb_MiniTable* m, const upb_Arena* arena));
+#endif  // UPB_TRACING_ENABLED
 
 #ifdef __cplusplus
 } /* extern "C" */
@@ -3110,6 +3652,12 @@ UPB_INLINE void upb_Message_LogNewMessage(const upb_MiniTable* mini_table,
 
 #endif /* UPB_MESSAGE_MESSAGE_H_ */
 
+#ifndef UPB_MINI_TABLE_TAGGED_PTR_H_
+#define UPB_MINI_TABLE_TAGGED_PTR_H_
+
+#include <stdint.h>
+
+
 // Must be last.
 
 // When a upb_Message* is stored in a message, array, or map, it is stored in a
@@ -3142,474 +3690,231 @@ UPB_API_INLINE upb_Message* upb_TaggedMessagePtr_GetNonEmptyMessage(
 
 #endif /* UPB_MINI_TABLE_TAGGED_PTR_H_ */
 
-#ifndef UPB_MINI_TABLE_SUB_H_
-#define UPB_MINI_TABLE_SUB_H_
-
-
 // Must be last.
 
-typedef union upb_MiniTableSub upb_MiniTableSub;
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-// Constructors
+// Functions ending in BaseField() take a (upb_MiniTableField*) argument
+// and work only on non-extension fields.
+//
+// Functions ending in Extension() take a (upb_MiniTableExtension*) argument
+// and work only on extensions.
 
-UPB_API_INLINE upb_MiniTableSub
-upb_MiniTableSub_FromEnum(const upb_MiniTableEnum* subenum);
+UPB_API_INLINE void upb_Message_Clear(upb_Message* msg, const upb_MiniTable* m);
 
-UPB_API_INLINE upb_MiniTableSub
-upb_MiniTableSub_FromMessage(const upb_MiniTable* submsg);
+UPB_API_INLINE void upb_Message_ClearBaseField(upb_Message* msg,
+                                               const upb_MiniTableField* f);
 
-// Getters
+UPB_API_INLINE void upb_Message_ClearExtension(upb_Message* msg,
+                                               const upb_MiniTableExtension* e);
 
-UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTableSub_Enum(
-    upb_MiniTableSub sub);
+UPB_API_INLINE void upb_Message_ClearOneof(upb_Message* msg,
+                                           const upb_MiniTable* m,
+                                           const upb_MiniTableField* f);
 
-UPB_API_INLINE const upb_MiniTable* upb_MiniTableSub_Message(
-    upb_MiniTableSub sub);
+UPB_API_INLINE bool upb_Message_HasBaseField(const upb_Message* msg,
+                                             const upb_MiniTableField* f);
 
-#ifdef __cplusplus
-} /* extern "C" */
-#endif
+UPB_API_INLINE bool upb_Message_HasExtension(const upb_Message* msg,
+                                             const upb_MiniTableExtension* e);
 
+UPB_API_INLINE upb_MessageValue
+upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* f,
+                     upb_MessageValue default_val);
 
-#endif /* UPB_MINI_TABLE_SUB_H_ */
+UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
+    const upb_Message* msg, const upb_MiniTableField* field,
+    upb_Message* default_val);
 
-// Must be last.
+UPB_API_INLINE const upb_Array* upb_Message_GetArray(
+    const upb_Message* msg, const upb_MiniTableField* f);
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+UPB_API_INLINE bool upb_Message_GetBool(const upb_Message* msg,
+                                        const upb_MiniTableField* f,
+                                        bool default_val);
 
-// Functions ending in BaseField() take a (upb_MiniTableField*) argument
-// and work only on non-extension fields.
-//
-// Functions ending in Extension() take a (upb_MiniTableExtension*) argument
-// and work only on extensions.
+UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
+                                            const upb_MiniTableField* field,
+                                            double default_val);
 
-UPB_API_INLINE void upb_Message_Clear(upb_Message* msg, const upb_MiniTable* m);
+UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          float default_val);
 
-UPB_API_INLINE void upb_Message_ClearBaseField(upb_Message* msg,
-                                               const upb_MiniTableField* f);
+UPB_API_INLINE int32_t upb_Message_GetInt32(const upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int32_t default_val);
 
-UPB_API_INLINE void upb_Message_ClearExtension(upb_Message* msg,
-                                               const upb_MiniTableExtension* e);
+UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int64_t default_val);
+
+UPB_API_INLINE const upb_Map* upb_Message_GetMap(const upb_Message* msg,
+                                                 const upb_MiniTableField* f);
+
+UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
+    const upb_Message* msg, const upb_MiniTableField* f);
+
+UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
+    upb_Message* msg, const upb_MiniTableField* f);
 
-UPB_API_INLINE bool upb_Message_HasBaseField(const upb_Message* msg,
-                                             const upb_MiniTableField* f);
+UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(upb_Message* msg,
+                                                  const upb_MiniTableField* f);
 
-UPB_API_INLINE bool upb_Message_HasExtension(const upb_Message* msg,
-                                             const upb_MiniTableExtension* e);
+UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
+    upb_Message* msg, const upb_MiniTableField* f);
 
-UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
-                                             const upb_MiniTableField* f,
-                                             const void* val);
+UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
+    upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena);
 
-UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
-                                             const upb_MiniTableExtension* e,
-                                             const void* val, upb_Arena* a);
+UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
+    upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena);
 
-UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
-    const upb_Message* message, const upb_MiniTableField* oneof_field) {
-  UPB_ASSUME(upb_MiniTableField_IsInOneof(oneof_field));
-  return UPB_PRIVATE(_upb_Message_GetOneofCase)(message, oneof_field);
-}
+UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
+    upb_Message* msg, const upb_MiniTable* mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena);
 
-// NOTE: The default_val is only used for fields that support presence.
-// For repeated/map fields, the resulting upb_Array*/upb_Map* can be NULL if a
-// upb_Array/upb_Map has not been allocated yet. Array/map fields do not have
-// presence, so this is semantically identical to a pointer to an empty
-// array/map, and must be treated the same for all semantic purposes.
-UPB_INLINE upb_MessageValue
-upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* field,
-                     upb_MessageValue default_val) {
-  upb_MessageValue ret;
-  if (upb_MiniTableField_IsExtension(field)) {
-    _upb_Message_GetExtensionField(msg, (upb_MiniTableExtension*)field,
-                                   &default_val, &ret);
-  } else {
-    _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  }
-  return ret;
-}
+UPB_API_INLINE upb_StringView
+upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
+                      upb_StringView default_val);
 
-// Sets the value of the given field in the given msg. The return value is true
-// if the operation completed successfully, or false if memory allocation
-// failed.
-UPB_INLINE bool UPB_PRIVATE(_upb_Message_SetField)(
-    upb_Message* msg, const upb_MiniTableField* field, upb_MessageValue val,
-    upb_Arena* a) {
-  if (upb_MiniTableField_IsExtension(field)) {
-    const upb_MiniTableExtension* ext = (const upb_MiniTableExtension*)field;
-    return upb_Message_SetExtension(msg, ext, &val, a);
-  } else {
-    upb_Message_SetBaseField(msg, field, &val);
-    return true;
-  }
-}
+UPB_API_INLINE uint32_t upb_Message_GetUInt32(const upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint32_t default_val);
 
-UPB_API_INLINE bool upb_Message_GetBool(const upb_Message* msg,
-                                        const upb_MiniTableField* field,
-                                        bool default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Bool);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_1Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue def;
-  def.bool_val = default_val;
-  return upb_Message_GetField(msg, field, def).bool_val;
-}
+UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint64_t default_val);
 
-UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
-                                        const upb_MiniTableField* field,
-                                        bool value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Bool);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_1Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.bool_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetClosedEnum(
+    upb_Message* msg, const upb_MiniTable* msg_mini_table,
+    const upb_MiniTableField* f, int32_t value);
 
-UPB_API_INLINE int32_t upb_Message_GetInt32(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            int32_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int32 ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Enum);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+// BaseField Setters ///////////////////////////////////////////////////////////
 
-  upb_MessageValue def;
-  def.int32_val = default_val;
-  return upb_Message_GetField(msg, field, def).int32_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
+                                             const upb_MiniTableField* f,
+                                             const void* val);
 
-UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         int32_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int32 ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Enum);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.int32_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldBool(struct upb_Message* msg,
+                                                 const upb_MiniTableField* f,
+                                                 bool value);
 
-UPB_API_INLINE uint32_t upb_Message_GetUInt32(const upb_Message* msg,
-                                              const upb_MiniTableField* field,
-                                              uint32_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt32);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE void upb_Message_SetBaseFieldDouble(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   double value);
 
-  upb_MessageValue def;
-  def.uint32_val = default_val;
-  return upb_Message_GetField(msg, field, def).uint32_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldFloat(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  float value);
 
-UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          uint32_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt32);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.uint32_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldInt32(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int32_t value);
 
-UPB_API_INLINE void upb_Message_SetClosedEnum(
-    upb_Message* msg, const upb_MiniTable* msg_mini_table,
-    const upb_MiniTableField* field, int32_t value) {
-  UPB_ASSERT(upb_MiniTableField_IsClosedEnum(field));
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  UPB_ASSERT(upb_MiniTableEnum_CheckValue(
-      upb_MiniTable_GetSubEnumTable(msg_mini_table, field), value));
-  upb_Message_SetBaseField(msg, field, &value);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldInt64(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int64_t value);
 
-UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            int64_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE void upb_Message_SetBaseFieldString(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_StringView value);
 
-  upb_MessageValue def;
-  def.int64_val = default_val;
-  return upb_Message_GetField(msg, field, def).int64_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt32(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint32_t value);
 
-UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         int64_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.int64_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt64(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint64_t value);
 
-UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
-                                              const upb_MiniTableField* field,
-                                              uint64_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+// Extension Setters ///////////////////////////////////////////////////////////
 
-  upb_MessageValue def;
-  def.uint64_val = default_val;
-  return upb_Message_GetField(msg, field, def).uint64_val;
-}
+UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
+                                             const upb_MiniTableExtension* e,
+                                             const void* value, upb_Arena* a);
 
-UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          uint64_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.uint64_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetExtensionBool(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, bool value,
+    upb_Arena* a);
 
-UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          float default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Float);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE bool upb_Message_SetExtensionDouble(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, double value,
+    upb_Arena* a);
 
-  upb_MessageValue def;
-  def.float_val = default_val;
-  return upb_Message_GetField(msg, field, def).float_val;
-}
+UPB_API_INLINE bool upb_Message_SetExtensionFloat(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, float value,
+    upb_Arena* a);
 
-UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         float value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Float);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.float_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetExtensionInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int32_t value,
+    upb_Arena* a);
 
-UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            double default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Double);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE bool upb_Message_SetExtensionInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int64_t value,
+    upb_Arena* a);
 
-  upb_MessageValue def;
-  def.double_val = default_val;
-  return upb_Message_GetField(msg, field, def).double_val;
-}
+UPB_API_INLINE bool upb_Message_SetExtensionString(
+    struct upb_Message* msg, const upb_MiniTableExtension* e,
+    upb_StringView value, upb_Arena* a);
 
-UPB_API_INLINE bool upb_Message_SetDouble(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          double value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Double);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.double_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetExtensionUInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint32_t value,
+    upb_Arena* a);
 
-UPB_API_INLINE upb_StringView
-upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
-                      upb_StringView default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_String ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Bytes);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_StringView);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE bool upb_Message_SetExtensionUInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint64_t value,
+    upb_Arena* a);
 
-  upb_MessageValue def;
-  def.str_val = default_val;
-  return upb_Message_GetField(msg, field, def).str_val;
-}
+// Universal Setters ///////////////////////////////////////////////////////////
 
-// Sets the value of a `string` or `bytes` field. The bytes of the value are not
-// copied, so it is the caller's responsibility to ensure that they remain valid
-// for the lifetime of `msg`. That might be done by copying them into the given
-// arena, or by fusing that arena with the arena the bytes live in, for example.
-UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          upb_StringView value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_String ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Bytes);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_StringView);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.str_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
+                                        const upb_MiniTableField* f, bool value,
+                                        upb_Arena* a);
 
-UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
-    const upb_Message* msg, const upb_MiniTableField* field,
-    upb_Message* default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_TaggedMessagePtr tagged;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
-  return tagged;
-}
+UPB_API_INLINE bool upb_Message_SetDouble(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          double value, upb_Arena* a);
 
-UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  upb_TaggedMessagePtr tagged =
-      upb_Message_GetTaggedMessagePtr(msg, field, NULL);
-  return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
-}
+UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         float value, upb_Arena* a);
 
-UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  return (upb_Message*)upb_Message_GetMessage(msg, field);
-}
+UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int32_t value, upb_Arena* a);
 
-// For internal use only; users cannot set tagged messages because only the
-// parser and the message copier are allowed to directly create an empty
-// message.
-UPB_API_INLINE void _upb_Message_SetTaggedMessagePtr(
-    upb_Message* msg, const upb_MiniTable* mini_table,
-    const upb_MiniTableField* field, upb_TaggedMessagePtr sub_message) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  UPB_ASSERT(upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]));
-  upb_Message_SetBaseField(msg, field, &sub_message);
-}
+UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int64_t value, upb_Arena* a);
 
-// Sets the value of a message-typed field. The `mini_table` and `field`
-// parameters belong to `msg`, not `sub_message`. The mini_tables of `msg` and
-// `sub_message` must have been linked for this to work correctly.
 UPB_API_INLINE void upb_Message_SetMessage(upb_Message* msg,
-                                           const upb_MiniTable* mini_table,
-                                           const upb_MiniTableField* field,
-                                           upb_Message* sub_message) {
-  _upb_Message_SetTaggedMessagePtr(
-      msg, mini_table, field,
-      UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(sub_message, false));
-}
+                                           const upb_MiniTableField* f,
+                                           upb_Message* value);
 
-UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
-    upb_Message* msg, const upb_MiniTable* mini_table,
-    const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSERT(arena);
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  upb_Message* sub_message =
-      *UPB_PTR_AT(msg, field->UPB_ONLYBITS(offset), upb_Message*);
-  if (!sub_message) {
-    const upb_MiniTable* sub_mini_table = upb_MiniTableSub_Message(
-        mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]);
-    UPB_ASSERT(sub_mini_table);
-    sub_message = _upb_Message_New(sub_mini_table, arena);
-    *UPB_PTR_AT(msg, field->UPB_ONLYBITS(offset), upb_Message*) = sub_message;
-    UPB_PRIVATE(_upb_Message_SetPresence)(msg, field);
-  }
-  return sub_message;
-}
+UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          upb_StringView value, upb_Arena* a);
 
-UPB_API_INLINE const upb_Array* upb_Message_GetArray(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* ret;
-  const upb_Array* default_val = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  return ret;
-}
+UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint32_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  return (upb_Array*)upb_Message_GetArray(msg, field);
-}
+UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint64_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
-    upb_Message* msg, const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSERT(arena);
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* array = upb_Message_GetMutableArray(msg, field);
-  if (!array) {
-    array = UPB_PRIVATE(_upb_Array_New)(
-        arena, 4, UPB_PRIVATE(_upb_MiniTableField_ElemSizeLg2)(field));
-    // Check again due to: https://godbolt.org/z/7WfaoKG1r
-    UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-    upb_MessageValue val;
-    val.array_val = array;
-    UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, arena);
-  }
-  return array;
-}
+////////////////////////////////////////////////////////////////////////////////
 
 UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
-    upb_Message* msg, const upb_MiniTableField* field, size_t size,
-    upb_Arena* arena) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* arr = upb_Message_GetOrCreateMutableArray(msg, field, arena);
-  if (!arr || !UPB_PRIVATE(_upb_Array_ResizeUninitialized)(arr, size, arena)) {
-    return NULL;
-  }
-  return upb_Array_MutableDataPtr(arr);
-}
-
-UPB_API_INLINE const upb_Map* upb_Message_GetMap(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-  _upb_Message_AssertMapIsUntagged(msg, field);
-  upb_Map* ret;
-  const upb_Map* default_val = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  return ret;
-}
-
-UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  return (upb_Map*)upb_Message_GetMap(msg, field);
-}
+    upb_Message* msg, const upb_MiniTableField* f, size_t size,
+    upb_Arena* arena);
 
-UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
-    upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
-    const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  const upb_MiniTableField* map_entry_key_field =
-      &map_entry_mini_table->UPB_ONLYBITS(fields)[0];
-  const upb_MiniTableField* map_entry_value_field =
-      &map_entry_mini_table->UPB_ONLYBITS(fields)[1];
-  return _upb_Message_GetOrCreateMutableMap(
-      msg, field,
-      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_key_field)),
-      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_value_field)),
-      arena);
-}
+UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
+    const upb_Message* message, const upb_MiniTableField* oneof_field);
 
 // Updates a map entry given an entry message.
 bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* mini_table,
@@ -3676,6 +3981,41 @@ UPB_INLINE void _upb_msg_map_set_value(void* msg, const void* val,
 #define UPB_MINI_TABLE_DECODE_H_
 
 
+#ifndef UPB_MINI_TABLE_SUB_H_
+#define UPB_MINI_TABLE_SUB_H_
+
+
+// Must be last.
+
+typedef union upb_MiniTableSub upb_MiniTableSub;
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Constructors
+
+UPB_API_INLINE upb_MiniTableSub
+upb_MiniTableSub_FromEnum(const upb_MiniTableEnum* subenum);
+
+UPB_API_INLINE upb_MiniTableSub
+upb_MiniTableSub_FromMessage(const upb_MiniTable* submsg);
+
+// Getters
+
+UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTableSub_Enum(
+    upb_MiniTableSub sub);
+
+UPB_API_INLINE const upb_MiniTable* upb_MiniTableSub_Message(
+    upb_MiniTableSub sub);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+
+#endif /* UPB_MINI_TABLE_SUB_H_ */
+
 // Export the newer headers, for legacy users.  New users should include the
 // more specific headers directly.
 // IWYU pragma: begin_exports
@@ -4392,7 +4732,8 @@ TAGBYTES(r)
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
@@ -4896,7 +5237,8 @@ UPB_FORCEINLINE bool upb_EpsCopyInputStream_TryParseDelimitedFast(
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
@@ -11857,6 +12199,7 @@ bool upb_FieldDef_HasOptions(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_HasPresence(const upb_FieldDef* f);
 bool upb_FieldDef_HasSubDef(const upb_FieldDef* f);
 uint32_t upb_FieldDef_Index(const upb_FieldDef* f);
+UPB_API bool upb_FieldDef_IsEnum(const upb_FieldDef* f);
 bool upb_FieldDef_IsExtension(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_IsMap(const upb_FieldDef* f);
 bool upb_FieldDef_IsOptional(const upb_FieldDef* f);
diff --git a/rust/BUILD b/rust/BUILD
index 4aa9cb0280..aff4d2bec1 100644
--- a/rust/BUILD
+++ b/rust/BUILD
@@ -48,14 +48,12 @@ rust_library(
 PROTOBUF_SHARED = [
     "enum.rs",
     "internal.rs",
-    "macros.rs",
-    "optional.rs",
     "primitive.rs",
+    "optional.rs",
     "proxied.rs",
     "repeated.rs",
     "shared.rs",
     "string.rs",
-    "vtable.rs",
     "map.rs",
     "proto_macro.rs",
 ]
@@ -172,6 +170,11 @@ proto_lang_toolchain(
     visibility = ["//visibility:public"],
 )
 
+package_group(
+    name = "rust_proto_library_allowed_in_different_package",
+    packages = ["//rust/test"],  # for unittest proto_libraries
+)
+
 # This flag controls what kernel all Rust Protobufs are using in the current build.
 string_flag(
     name = "rust_proto_library_kernel",
diff --git a/rust/aspects.bzl b/rust/aspects.bzl
index 7a714ea6b8..bd5f1ca74f 100644
--- a/rust/aspects.bzl
+++ b/rust/aspects.bzl
@@ -4,6 +4,7 @@ Disclaimer: This project is experimental, under heavy development, and should no
 be used yet."""
 
 load("@bazel_tools//tools/cpp:toolchain_utils.bzl", "find_cpp_toolchain")
+load("@rules_proto//proto:defs.bzl", "ProtoInfo", "proto_common")
 
 # buildifier: disable=bzl-visibility
 load("@rules_rust//rust/private:providers.bzl", "CrateInfo", "DepInfo", "DepVariantInfo")
@@ -12,8 +13,6 @@ load("@rules_rust//rust/private:providers.bzl", "CrateInfo", "DepInfo", "DepVari
 load("@rules_rust//rust/private:rustc.bzl", "rustc_compile_action")
 load("//bazel:upb_proto_library.bzl", "UpbWrappedCcInfo", "upb_proto_library_aspect")
 
-proto_common = proto_common_do_not_use
-
 visibility(["//rust/..."])
 
 CrateMappingInfo = provider(
@@ -34,6 +33,12 @@ RustProtoInfo = provider(
     },
 )
 
+def proto_rust_toolchain_label(is_upb):
+    if is_upb:
+        return "//rust:proto_rust_upb_toolchain"
+    else:
+        return "//rust:proto_rust_cpp_toolchain"
+
 def _register_crate_mapping_write_action(name, actions, crate_mappings):
     """Registers an action that generates a crate mapping for a proto_library.
 
@@ -266,10 +271,6 @@ def _compile_rust(ctx, attr, src, extra_srcs, deps):
         build_info = None,
     )
 
-def _is_cc_proto_library(rule):
-    """Detects if the current rule is a cc_proto_library."""
-    return rule.kind == "cc_proto_library"
-
 def _rust_upb_proto_aspect_impl(target, ctx):
     """Implements the Rust protobuf aspect logic for UPB kernel."""
     return _rust_proto_aspect_common(target, ctx, is_upb = True)
@@ -288,12 +289,6 @@ def _rust_proto_aspect_common(target, ctx, is_upb):
     if RustProtoInfo in target:
         return []
 
-    if _is_cc_proto_library(ctx.rule):
-        # This is cc_proto_library, but we need the RustProtoInfo provider of the proto_library that
-        # this aspect provides. Luckily this aspect has already been attached on the proto_library
-        # so we can just read the provider.
-        return [ctx.rule.attr.deps[0][RustProtoInfo]]
-
     proto_lang_toolchain = ctx.attr._proto_lang_toolchain[proto_common.ProtoLangToolchainInfo]
     cc_toolchain = find_cpp_toolchain(ctx)
 
@@ -329,13 +324,17 @@ def _rust_proto_aspect_common(target, ctx, is_upb):
     if is_upb:
         thunks_cc_info = target[UpbWrappedCcInfo].cc_info_with_thunks
     else:
+        dep_cc_infos = []
+        for dep in proto_deps:
+            dep_cc_infos.append(dep[CcInfo])
+
         thunks_cc_info = cc_common.merge_cc_infos(cc_infos = [_compile_cc(
             feature_configuration = feature_configuration,
             src = thunk,
             ctx = ctx,
             attr = attr,
             cc_toolchain = cc_toolchain,
-            cc_infos = [target[CcInfo], ctx.attr._cpp_thunks_deps[CcInfo]],
+            cc_infos = [target[CcInfo], ctx.attr._cpp_thunks_deps[CcInfo]] + dep_cc_infos,
         ) for thunk in thunks])
 
     runtime = proto_lang_toolchain.runtime
@@ -372,7 +371,6 @@ def _make_proto_library_aspect(is_upb):
         implementation = (_rust_upb_proto_aspect_impl if is_upb else _rust_cc_proto_aspect_impl),
         attr_aspects = ["deps"],
         requires = ([upb_proto_library_aspect] if is_upb else [cc_proto_aspect]),
-        required_aspect_providers = ([] if is_upb else [CcInfo]),
         attrs = {
             "_cc_toolchain": attr.label(
                 doc = (
@@ -413,9 +411,7 @@ def _make_proto_library_aspect(is_upb):
                 cfg = "exec",
             ),
             "_proto_lang_toolchain": attr.label(
-                default = Label(
-                    "//rust:proto_rust_upb_toolchain" if is_upb else "//rust:proto_rust_cpp_toolchain",
-                ),
+                default = Label(proto_rust_toolchain_label(is_upb)),
             ),
         },
         fragments = ["cpp"],
diff --git a/rust/cpp.rs b/rust/cpp.rs
index 225c97e519..2a199dcc61 100644
--- a/rust/cpp.rs
+++ b/rust/cpp.rs
@@ -10,7 +10,7 @@
 use crate::__internal::{Enum, Private};
 use crate::{
     Map, MapIter, Mut, ProtoStr, Proxied, ProxiedInMapValue, ProxiedInRepeated, Repeated,
-    RepeatedMut, RepeatedView, SettableValue, View,
+    RepeatedMut, RepeatedView, View,
 };
 use core::fmt::Debug;
 use paste::paste;
@@ -171,6 +171,13 @@ impl Deref for SerializedData {
     }
 }
 
+// TODO: remove after IntoProxied has been implemented for bytes.
+impl AsRef<[u8]> for SerializedData {
+    fn as_ref(&self) -> &[u8] {
+        self
+    }
+}
+
 impl Drop for SerializedData {
     fn drop(&mut self) {
         // SAFETY: `data` was allocated by the Rust global allocator with a
@@ -185,15 +192,6 @@ impl fmt::Debug for SerializedData {
     }
 }
 
-impl SettableValue<[u8]> for SerializedData {
-    fn set_on<'msg>(self, _private: Private, mut mutator: Mut<'msg, [u8]>)
-    where
-        [u8]: 'msg,
-    {
-        mutator.set(self.as_ref())
-    }
-}
-
 /// A type to transfer an owned Rust string across the FFI boundary:
 ///   * This struct is ABI-compatible with the equivalent C struct.
 ///   * It owns its data but does not drop it. Immediately turn it into a
@@ -235,32 +233,8 @@ pub fn debug_string(_private: Private, msg: RawMessage, f: &mut fmt::Formatter<'
     write!(f, "{dbg_str}")
 }
 
-pub type MessagePresentMutData<'msg, T> = crate::vtable::RawVTableOptionalMutatorData<'msg, T>;
-pub type MessageAbsentMutData<'msg, T> = crate::vtable::RawVTableOptionalMutatorData<'msg, T>;
-pub type BytesPresentMutData<'msg> = crate::vtable::RawVTableOptionalMutatorData<'msg, [u8]>;
-pub type BytesAbsentMutData<'msg> = crate::vtable::RawVTableOptionalMutatorData<'msg, [u8]>;
-pub type InnerBytesMut<'msg> = crate::vtable::RawVTableMutator<'msg, [u8]>;
-pub type InnerPrimitiveMut<'msg, T> = crate::vtable::RawVTableMutator<'msg, T>;
 pub type RawMapIter = UntypedMapIterator;
 
-#[derive(Debug)]
-pub struct MessageVTable {
-    pub getter: unsafe extern "C" fn(msg: RawMessage) -> RawMessage,
-    pub mut_getter: unsafe extern "C" fn(msg: RawMessage) -> RawMessage,
-    pub clearer: unsafe extern "C" fn(msg: RawMessage),
-}
-
-impl MessageVTable {
-    pub const fn new(
-        _private: Private,
-        getter: unsafe extern "C" fn(msg: RawMessage) -> RawMessage,
-        mut_getter: unsafe extern "C" fn(msg: RawMessage) -> RawMessage,
-        clearer: unsafe extern "C" fn(msg: RawMessage),
-    ) -> Self {
-        MessageVTable { getter, mut_getter, clearer }
-    }
-}
-
 /// The raw contents of every generated message.
 #[derive(Debug)]
 pub struct MessageInner {
@@ -327,6 +301,10 @@ impl InnerRepeated {
     pub fn as_mut(&mut self) -> InnerRepeatedMut<'_> {
         InnerRepeatedMut::new(Private, self.raw)
     }
+
+    pub fn raw(&self) -> RawRepeatedField {
+        self.raw
+    }
 }
 
 /// The raw type-erased pointer version of `RepeatedMut`.
@@ -396,7 +374,8 @@ macro_rules! impl_repeated_primitives {
         $get_thunk:ident,
         $set_thunk:ident,
         $clear_thunk:ident,
-        $copy_from_thunk:ident $(,)?
+        $copy_from_thunk:ident,
+        $reserve_thunk:ident $(,)?
     ]),* $(,)?) => {
         $(
             extern "C" {
@@ -413,38 +392,53 @@ macro_rules! impl_repeated_primitives {
                     v: <$t as CppTypeConversions>::ElemType);
                 fn $clear_thunk(f: RawRepeatedField);
                 fn $copy_from_thunk(src: RawRepeatedField, dst: RawRepeatedField);
+                fn $reserve_thunk(
+                    f: RawRepeatedField,
+                    additional: usize);
             }
 
             unsafe impl ProxiedInRepeated for $t {
                 #[allow(dead_code)]
+                #[inline]
                 fn repeated_new(_: Private) -> Repeated<$t> {
                     Repeated::from_inner(InnerRepeated {
                         raw: unsafe { $new_thunk() }
                     })
                 }
                 #[allow(dead_code)]
+                #[inline]
                 unsafe fn repeated_free(_: Private, f: &mut Repeated<$t>) {
                     unsafe { $free_thunk(f.as_mut().as_raw(Private)) }
                 }
+                #[inline]
                 fn repeated_len(f: View<Repeated<$t>>) -> usize {
                     unsafe { $size_thunk(f.as_raw(Private)) }
                 }
+                #[inline]
                 fn repeated_push(mut f: Mut<Repeated<$t>>, v: View<$t>) {
                     unsafe { $add_thunk(f.as_raw(Private), v.into()) }
                 }
+                #[inline]
                 fn repeated_clear(mut f: Mut<Repeated<$t>>) {
                     unsafe { $clear_thunk(f.as_raw(Private)) }
                 }
+                #[inline]
                 unsafe fn repeated_get_unchecked(f: View<Repeated<$t>>, i: usize) -> View<$t> {
                     <$t as CppTypeConversions>::elem_to_view(
                         unsafe { $get_thunk(f.as_raw(Private), i) })
                 }
+                #[inline]
                 unsafe fn repeated_set_unchecked(mut f: Mut<Repeated<$t>>, i: usize, v: View<$t>) {
                     unsafe { $set_thunk(f.as_raw(Private), i, v.into()) }
                 }
+                #[inline]
                 fn repeated_copy_from(src: View<Repeated<$t>>, mut dest: Mut<Repeated<$t>>) {
                     unsafe { $copy_from_thunk(src.as_raw(Private), dest.as_raw(Private)) }
                 }
+                #[inline]
+                fn repeated_reserve(mut f: Mut<Repeated<$t>>, additional: usize) {
+                    unsafe { $reserve_thunk(f.as_raw(Private), additional) }
+                }
             }
         )*
     };
@@ -460,6 +454,7 @@ macro_rules! impl_repeated_primitives {
                     [< __pb_rust_RepeatedField_ $t _set >],
                     [< __pb_rust_RepeatedField_ $t _clear >],
                     [< __pb_rust_RepeatedField_ $t _copy_from >],
+                    [< __pb_rust_RepeatedField_ $t _reserve >],
                 ],
             )*);
         }
@@ -496,6 +491,17 @@ pub fn cast_enum_repeated_mut<E: Enum + ProxiedInRepeated>(
     }
 }
 
+/// Cast a `RepeatedMut<SomeEnum>` to `RepeatedMut<c_int>` and call
+/// repeated_reserve.
+pub fn reserve_enum_repeated_mut<E: Enum + ProxiedInRepeated>(
+    private: Private,
+    repeated: RepeatedMut<E>,
+    additional: usize,
+) {
+    let int_repeated = cast_enum_repeated_mut(private, repeated);
+    ProxiedInRepeated::repeated_reserve(int_repeated, additional);
+}
+
 #[derive(Debug)]
 pub struct InnerMap {
     pub(crate) raw: RawMap,
diff --git a/rust/cpp_kernel/cpp_api.cc b/rust/cpp_kernel/cpp_api.cc
index f37a1c7e5a..753331c287 100644
--- a/rust/cpp_kernel/cpp_api.cc
+++ b/rust/cpp_kernel/cpp_api.cc
@@ -42,6 +42,10 @@ extern "C" {
   void __pb_rust_RepeatedField_##rust_ty##_clear(                             \
       google::protobuf::RepeatedField<ty>* r) {                                         \
     r->Clear();                                                               \
+  }                                                                           \
+  void __pb_rust_RepeatedField_##rust_ty##_reserve(                           \
+      google::protobuf::RepeatedField<ty>* r, size_t additional) {                      \
+    r->Reserve(r->size() + additional);                                       \
   }
 
 expose_repeated_field_methods(int32_t, i32);
@@ -89,6 +93,10 @@ expose_repeated_field_methods(int64_t, i64);
   void __pb_rust_RepeatedField_##ty##_clear(                           \
       google::protobuf::RepeatedPtrField<std::string>* r) {                      \
     r->Clear();                                                        \
+  }                                                                    \
+  void __pb_rust_RepeatedField_##ty##_reserve(                         \
+      google::protobuf::RepeatedPtrField<std::string>* r, size_t additional) {   \
+    r->Reserve(r->size() + additional);                                \
   }
 
 expose_repeated_ptr_field_methods(ProtoStr);
diff --git a/rust/defs.bzl b/rust/defs.bzl
index 64c4022ed0..da65623139 100644
--- a/rust/defs.bzl
+++ b/rust/defs.bzl
@@ -3,9 +3,11 @@
 Disclaimer: This project is experimental, under heavy development, and should not
 be used yet."""
 
+load("@rules_proto//proto:defs.bzl", "ProtoInfo", "proto_common")
 load(
     "//rust:aspects.bzl",
     "RustProtoInfo",
+    "proto_rust_toolchain_label",
     "rust_cc_proto_library_aspect",
     "rust_upb_proto_library_aspect",
 )
@@ -65,6 +67,7 @@ def _rust_proto_library_impl(ctx):
 
     dep = deps[0]
     rust_proto_info = dep[RustProtoInfo]
+
     dep_variant_info = rust_proto_info.dep_variant_info
     return [
         dep_variant_info.crate_info,
@@ -79,9 +82,12 @@ def _make_rust_proto_library(is_upb):
         attrs = {
             "deps": attr.label_list(
                 mandatory = True,
-                providers = [ProtoInfo] if is_upb else [CcInfo],
+                providers = [ProtoInfo],
                 aspects = [rust_upb_proto_library_aspect if is_upb else rust_cc_proto_library_aspect],
             ),
+            "_proto_lang_toolchain": attr.label(
+                default = Label(proto_rust_toolchain_label(is_upb)),
+            ),
         },
     )
 
diff --git a/rust/enum.rs b/rust/enum.rs
index 847ef41df5..d9b2394e81 100644
--- a/rust/enum.rs
+++ b/rust/enum.rs
@@ -19,9 +19,16 @@ use std::{
 ///   representation as erased enums in the runtime.
 ///   - For C++, this is `proto2::RepeatedField<c_int>`
 ///   - For UPB, this is an array compatible with `int32`
-pub unsafe trait Enum {
+pub unsafe trait Enum: TryFrom<i32> {
     /// The name of the enum.
     const NAME: &'static str;
+
+    /// Returns `true` if the given numeric value matches one of the `Self`'s
+    /// defined values.
+    ///
+    /// If `Self` is a closed enum, then `TryFrom<i32>` for `value` succeeds if
+    /// and only if this function returns `true`.
+    fn is_known(value: i32) -> bool;
 }
 
 /// An integer value wasn't known for an enum while converting.
diff --git a/rust/internal.rs b/rust/internal.rs
index 4a9486e91a..f8118c88d6 100644
--- a/rust/internal.rs
+++ b/rust/internal.rs
@@ -13,11 +13,6 @@
 pub use paste::paste;
 
 pub use crate::r#enum::Enum;
-pub use crate::vtable::{
-    new_vtable_field_entry, BytesMutVTable, BytesOptionalMutVTable, PrimitiveOptionalMutVTable,
-    PrimitiveVTable, PrimitiveWithRawVTable, ProxiedWithRawOptionalVTable, ProxiedWithRawVTable,
-    RawVTableMutator, RawVTableOptionalMutatorData,
-};
 pub use crate::ProtoStr;
 
 // TODO: Temporarily re-export these symbols which are now under
diff --git a/rust/macros.rs b/rust/macros.rs
deleted file mode 100644
index 4f8334933e..0000000000
--- a/rust/macros.rs
+++ /dev/null
@@ -1,47 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2023 Google LLC.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-//! Runtime-internal macros
-
-/// Defines a `impl SettableValue<$proxied> for SomeType` body that forwards to
-/// another implementation.
-///
-/// # Example
-/// ```ignore
-/// impl<'a, const N: usize> SettableValue<[u8]> for &'a [u8; N] {
-///     // Use the `SettableValue<[u8]>` implementation for `&[u8]`:
-///     impl_forwarding_settable_value!([u8], self => &self[..]);
-/// }
-/// ```
-macro_rules! impl_forwarding_settable_value {
-    ($proxied:ty, $self:ident => $self_forwarding_expr:expr) => {
-        fn set_on<'b>(
-            $self,
-            _private: $crate::__internal::Private,
-            mutator: $crate::Mut<'b, $proxied>,
-        ) where $proxied: 'b {
-            ($self_forwarding_expr).set_on(Private, mutator)
-        }
-
-        fn set_on_absent(
-            $self,
-            _private: $crate::__internal::Private,
-            absent_mutator: <$proxied as $crate::ProxiedWithPresence>::AbsentMutData<'_>,
-        ) -> <$proxied as $crate::ProxiedWithPresence>::PresentMutData<'_> {
-            ($self_forwarding_expr).set_on_absent($crate::__internal::Private, absent_mutator)
-        }
-
-        fn set_on_present(
-            $self,
-            _private: $crate::__internal::Private,
-            present_mutator: <$proxied as $crate::ProxiedWithPresence>::PresentMutData<'_>,
-        ) {
-            ($self_forwarding_expr).set_on_present($crate::__internal::Private, present_mutator)
-        }
-    };
-}
-pub(crate) use impl_forwarding_settable_value;
diff --git a/rust/map.rs b/rust/map.rs
index 5ce74047b6..948e5bae52 100644
--- a/rust/map.rs
+++ b/rust/map.rs
@@ -6,7 +6,7 @@
 // https://developers.google.com/open-source/licenses/bsd
 
 use crate::{
-    Mut, MutProxy, Proxied, SettableValue, View, ViewProxy,
+    Mut, MutProxied, MutProxy, Proxied, View, ViewProxy,
     __internal::Private,
     __runtime::{InnerMap, InnerMapMut, RawMap, RawMapIter},
 };
@@ -95,18 +95,10 @@ where
 
 impl<K: Proxied + ?Sized, V: ProxiedInMapValue<K> + ?Sized> Proxied for Map<K, V> {
     type View<'msg> = MapView<'msg, K, V> where K: 'msg, V: 'msg;
-    type Mut<'msg> = MapMut<'msg, K, V> where K: 'msg, V: 'msg;
 }
 
-impl<'msg, K: Proxied + ?Sized, V: ProxiedInMapValue<K> + ?Sized> SettableValue<Map<K, V>>
-    for MapView<'msg, K, V>
-{
-    fn set_on<'b>(self, _private: Private, mut mutator: Mut<'b, Map<K, V>>)
-    where
-        Map<K, V>: 'b,
-    {
-        mutator.copy_from(self);
-    }
+impl<K: Proxied + ?Sized, V: ProxiedInMapValue<K> + ?Sized> MutProxied for Map<K, V> {
+    type Mut<'msg> = MapMut<'msg, K, V> where K: 'msg, V: 'msg;
 }
 
 impl<'msg, K: Proxied + ?Sized, V: ProxiedInMapValue<K> + ?Sized> ViewProxy<'msg>
@@ -529,13 +521,13 @@ mod tests {
         assert_that!(
             map.as_view().iter().collect::<Vec<_>>(),
             unordered_elements_are![
-                eq((3, ProtoStr::from_str("fizz"))),
-                eq((5, ProtoStr::from_str("buzz"))),
-                eq((15, ProtoStr::from_str("fizzbuzz")))
+                eq(&(3, ProtoStr::from_str("fizz"))),
+                eq(&(5, ProtoStr::from_str("buzz"))),
+                eq(&(15, ProtoStr::from_str("fizzbuzz")))
             ]
         );
         assert_that!(
-            map.as_view().into_iter().collect::<Vec<_>>(),
+            map.as_view(),
             unordered_elements_are![
                 eq((3, ProtoStr::from_str("fizz"))),
                 eq((5, ProtoStr::from_str("buzz"))),
@@ -543,7 +535,15 @@ mod tests {
             ]
         );
         assert_that!(
-            map.as_view().into_iter().collect::<Vec<_>>(),
+            map.as_mut().iter().collect::<Vec<_>>(),
+            unordered_elements_are![
+                eq(&(3, ProtoStr::from_str("fizz"))),
+                eq(&(5, ProtoStr::from_str("buzz"))),
+                eq(&(15, ProtoStr::from_str("fizzbuzz")))
+            ]
+        );
+        assert_that!(
+            map.as_mut(),
             unordered_elements_are![
                 eq((3, ProtoStr::from_str("fizz"))),
                 eq((5, ProtoStr::from_str("buzz"))),
@@ -559,10 +559,7 @@ mod tests {
         assert!(map_mut.insert(0, "fizz"));
         // insert should return false when the key is already present
         assert!(!map_mut.insert(0, "buzz"));
-        assert_that!(
-            map.as_mut().iter().collect::<Vec<_>>(),
-            unordered_elements_are![eq((0, ProtoStr::from_str("buzz"))),]
-        );
+        assert_that!(map.as_mut(), unordered_elements_are![eq((0, ProtoStr::from_str("buzz"))),]);
     }
 
     #[test]
@@ -576,7 +573,7 @@ mod tests {
         map_mut.extend([(0, "fizz"), (1, "buzz"), (2, "fizzbuzz")]);
 
         assert_that!(
-            map.as_view().into_iter().collect::<Vec<_>>(),
+            map.as_view(),
             unordered_elements_are![
                 eq((0, ProtoStr::from_str("fizz"))),
                 eq((1, ProtoStr::from_str("buzz"))),
@@ -592,7 +589,7 @@ mod tests {
         map_mut.extend(&map_2);
 
         assert_that!(
-            map.as_view().into_iter().collect::<Vec<_>>(),
+            map.as_view(),
             unordered_elements_are![
                 eq((0, ProtoStr::from_str("fizz"))),
                 eq((1, ProtoStr::from_str("buzz"))),
@@ -609,7 +606,7 @@ mod tests {
         map_mut.copy_from([(0, "fizz"), (1, "buzz"), (2, "fizzbuzz")]);
 
         assert_that!(
-            map.as_view().into_iter().collect::<Vec<_>>(),
+            map.as_view(),
             unordered_elements_are![
                 eq((0, ProtoStr::from_str("fizz"))),
                 eq((1, ProtoStr::from_str("buzz"))),
@@ -625,7 +622,7 @@ mod tests {
         map_mut.copy_from(&map_2);
 
         assert_that!(
-            map.as_view().into_iter().collect::<Vec<_>>(),
+            map.as_view(),
             unordered_elements_are![
                 eq((2, ProtoStr::from_str("bing"))),
                 eq((3, ProtoStr::from_str("bong")))
diff --git a/rust/optional.rs b/rust/optional.rs
index 0268c61bfd..1f5cb9ad46 100644
--- a/rust/optional.rs
+++ b/rust/optional.rs
@@ -10,7 +10,7 @@
 #![allow(unused)]
 
 use crate::__internal::Private;
-use crate::{Mut, MutProxy, Proxied, ProxiedWithPresence, SettableValue, View, ViewProxy};
+use crate::{Mut, MutProxied, MutProxy, Proxied, View, ViewProxy};
 use std::convert::{AsMut, AsRef};
 use std::fmt::{self, Debug};
 use std::panic;
@@ -21,9 +21,6 @@ use std::ptr;
 /// This can be pattern matched with `match` or `if let` to determine if the
 /// field is set and access the field data.
 ///
-/// [`FieldEntry`], a specific type alias for `Optional`, provides much of the
-/// functionality for this type.
-///
 /// Two `Optional`s are equal if they match both presence and the field values.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum Optional<SetVal, UnsetVal = SetVal> {
@@ -80,670 +77,3 @@ impl<T> From<Optional<T>> for Option<T> {
         x.into_option()
     }
 }
-
-/// A mutable view into the value of an optional field, which may be set or
-/// unset.
-pub type FieldEntry<'msg, T> = Optional<PresentField<'msg, T>, AbsentField<'msg, T>>;
-
-/// Methods for `_mut()` accessors of optional types.
-///
-/// The most common methods are [`set`] and [`or_default`].
-impl<'msg, T: ProxiedWithPresence + ?Sized + 'msg> FieldEntry<'msg, T> {
-    // is_set() is provided by `impl<T, A> Optional<T, A>`
-
-    /// Gets a mutator for this field. Sets to the default value if not set.
-    pub fn or_default(self) -> Mut<'msg, T> {
-        match self {
-            Optional::Set(x) => x.into_mut(),
-            Optional::Unset(x) => x.set_default().into_mut(),
-        }
-    }
-
-    /// Gets a mutator for this field. Sets to the given `val` if not set.
-    ///
-    /// If the field is already set, `val` is ignored.
-    pub fn or_set(self, val: impl SettableValue<T>) -> Mut<'msg, T> {
-        self.or_set_with(move || val)
-    }
-
-    /// Gets a mutator for this field. Sets using the given `val` function if
-    /// not set.
-    ///
-    /// If the field is already set, `val` is not invoked.
-    pub fn or_set_with<S>(self, val: impl FnOnce() -> S) -> Mut<'msg, T>
-    where
-        S: SettableValue<T>,
-    {
-        match self {
-            Optional::Set(x) => x.into_mut(),
-            Optional::Unset(x) => x.set(val()).into_mut(),
-        }
-    }
-
-    /// Sets the value of this field to `val`.
-    ///
-    /// Equivalent to `self.or_default().set(val)`, but does not consume `self`.
-    ///
-    /// `set` has the same parameters as in [`MutProxy`], so making a field
-    /// `optional` will switch to using this method. This makes transitioning
-    /// from implicit to explicit presence easier.
-    pub fn set(&mut self, val: impl SettableValue<T>) {
-        transform_mut(self, |mut self_| match self_ {
-            Optional::Set(ref mut present) => {
-                present.set(val);
-                self_
-            }
-            Optional::Unset(absent) => Optional::Set(absent.set(val)),
-        })
-    }
-
-    /// Clears the field; `is_set()` will return `false`.
-    pub fn clear(&mut self) {
-        transform_mut(self, |self_| match self_ {
-            Optional::Set(present) => Optional::Unset(present.clear()),
-            absent => absent,
-        })
-    }
-
-    /// Gets an immutable view of this field, using its default value if not
-    /// set. This is shorthand for `as_view`.
-    ///
-    /// This provides a shorter lifetime than `into_view` but can also be called
-    /// multiple times - if the result of `get` is not living long enough
-    /// for your use, use that instead.
-    ///
-    /// `get` has the same parameters as in [`MutProxy`], so making a field
-    /// `optional` will switch to using this method. This makes transitioning
-    /// from implicit to explicit presence easier.
-    pub fn get(&self) -> View<'_, T> {
-        self.as_view()
-    }
-
-    /// Converts to an immutable view of this optional field, preserving the
-    /// field's presence.
-    pub fn into_optional_view(self) -> Optional<View<'msg, T>> {
-        let is_set = self.is_set();
-        Optional::new(self.into_view(), is_set)
-    }
-
-    /// Returns a field mutator if the field is set.
-    ///
-    /// Returns `None` if the field is not set. This does not affect `is_set()`.
-    ///
-    /// This returns `Option` and _not_ `Optional` since returning a defaulted
-    /// `Mut` would require mutating the presence of the field - for that
-    /// behavior, use `or_default()`.
-    pub fn try_into_mut(self) -> Option<Mut<'msg, T>> {
-        match self {
-            Optional::Set(x) => Some(x.into_mut()),
-            Optional::Unset(_) => None,
-        }
-    }
-}
-
-impl<'msg, T: ProxiedWithPresence + ?Sized + 'msg> ViewProxy<'msg> for FieldEntry<'msg, T> {
-    type Proxied = T;
-
-    fn as_view(&self) -> View<'_, T> {
-        match self {
-            Optional::Set(x) => x.as_view(),
-            Optional::Unset(x) => x.as_view(),
-        }
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, T>
-    where
-        'msg: 'shorter,
-    {
-        match self {
-            Optional::Set(x) => x.into_view(),
-            Optional::Unset(x) => x.into_view(),
-        }
-    }
-}
-
-// `MutProxy` not implemented for `FieldEntry` since the field may not be set,
-// and `as_mut`/`into_mut` should not insert.
-
-/// A field mutator capable of clearing that is statically known to point to a
-/// set field.
-pub struct PresentField<'msg, T>
-where
-    T: ProxiedWithPresence + ?Sized + 'msg,
-{
-    pub(crate) inner: T::PresentMutData<'msg>,
-}
-
-impl<'msg, T: ProxiedWithPresence + ?Sized + 'msg> Debug for PresentField<'msg, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.inner.fmt(f)
-    }
-}
-
-impl<'msg, T: ProxiedWithPresence + ?Sized + 'msg> PresentField<'msg, T> {
-    #[doc(hidden)]
-    pub fn from_inner(_private: Private, inner: T::PresentMutData<'msg>) -> Self {
-        Self { inner }
-    }
-
-    /// Gets an immutable view of this present field. This is shorthand for
-    /// `as_view`.
-    ///
-    /// This provides a shorter lifetime than `into_view` but can also be called
-    /// multiple times - if the result of `get` is not living long enough
-    /// for your use, use that instead.
-    pub fn get(&self) -> View<'_, T> {
-        self.as_view()
-    }
-
-    pub fn set(&mut self, val: impl SettableValue<T>) {
-        val.set_on(Private, self.as_mut())
-    }
-
-    /// See [`FieldEntry::clear`].
-    pub fn clear(mut self) -> AbsentField<'msg, T> {
-        AbsentField { inner: T::clear_present_field(self.inner) }
-    }
-
-    // This cannot provide `reborrow` - `clear` consumes after setting the field
-    // because it would violate a condition of `PresentField` - the field being set.
-}
-
-impl<'msg, T> ViewProxy<'msg> for PresentField<'msg, T>
-where
-    T: ProxiedWithPresence + ?Sized + 'msg,
-{
-    type Proxied = T;
-
-    fn as_view(&self) -> View<'_, T> {
-        self.inner.as_view()
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, T>
-    where
-        'msg: 'shorter,
-    {
-        self.inner.into_view()
-    }
-}
-
-impl<'msg, T> MutProxy<'msg> for PresentField<'msg, T>
-where
-    T: ProxiedWithPresence + ?Sized + 'msg,
-{
-    fn as_mut(&mut self) -> Mut<'_, T> {
-        self.inner.as_mut()
-    }
-
-    fn into_mut<'shorter>(self) -> Mut<'shorter, T>
-    where
-        'msg: 'shorter,
-    {
-        self.inner.into_mut()
-    }
-}
-
-/// A field mutator capable of setting that is statically known to point to a
-/// non-set field.
-pub struct AbsentField<'msg, T>
-where
-    T: ProxiedWithPresence + ?Sized + 'msg,
-{
-    pub(crate) inner: T::AbsentMutData<'msg>,
-}
-
-impl<'msg, T: ProxiedWithPresence + ?Sized + 'msg> Debug for AbsentField<'msg, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.inner.fmt(f)
-    }
-}
-
-impl<'msg, T: ProxiedWithPresence + ?Sized> AbsentField<'msg, T> {
-    #[doc(hidden)]
-    pub fn from_inner(_private: Private, inner: T::AbsentMutData<'msg>) -> Self {
-        Self { inner }
-    }
-
-    /// Gets the default value for this unset field.
-    ///
-    /// This is the same value that the primitive accessor would provide, though
-    /// with the shorter lifetime of `as_view`.
-    pub fn default_value(&self) -> View<'_, T> {
-        self.as_view()
-    }
-
-    /// See [`FieldEntry::set`]. Note that this consumes and returns a
-    /// `PresentField`.
-    pub fn set(self, val: impl SettableValue<T>) -> PresentField<'msg, T> {
-        PresentField { inner: val.set_on_absent(Private, self.inner) }
-    }
-
-    /// Sets this absent field to its default value.
-    pub fn set_default(self) -> PresentField<'msg, T> {
-        PresentField { inner: T::set_absent_to_default(self.inner) }
-    }
-
-    // This cannot provide `reborrow` - `set` consumes after setting the field
-    // because it would violate a condition of `AbsentField` - the field being
-    // unset.
-}
-
-impl<'msg, T> ViewProxy<'msg> for AbsentField<'msg, T>
-where
-    T: ProxiedWithPresence + ?Sized + 'msg,
-{
-    type Proxied = T;
-
-    fn as_view(&self) -> View<'_, T> {
-        self.inner.as_view()
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, T>
-    where
-        'msg: 'shorter,
-    {
-        self.inner.into_view()
-    }
-}
-
-/// Transforms a mutable reference in-place, treating it as if it were owned.
-///
-/// The program will abort if `transform` panics.
-///
-/// This is the same operation as provided by [`take_mut::take`].
-///
-/// [`take_mut::take`]: https://docs.rs/take_mut/latest/take_mut/fn.take.html
-fn transform_mut<T>(mut_ref: &mut T, transform: impl FnOnce(T) -> T) {
-    #[cold]
-    #[inline(never)]
-    fn panicked_in_transform_mut() -> ! {
-        use std::io::Write as _;
-        let backtrace = std::backtrace::Backtrace::force_capture();
-        let stderr = std::io::stderr();
-        let mut stderr = stderr.lock();
-        let _ = write!(&mut stderr, "BUG: A protobuf mutator panicked! Backtrace:\n{backtrace}\n");
-        let _ = stderr.flush();
-        std::process::abort()
-    }
-
-    // https://play.rust-lang.org/?edition=2021&gist=f3014e1f209013f0a38352e211f4a240
-    // provides a sample test to confirm this operation is sound in Miri.
-    // SAFETY:
-    // - `old_t` is not dropped without also replacing `*mut_ref`, preventing a
-    //   double-free.
-    // - If `transform` panics, the process aborts since `*mut_ref` has no possible
-    //   valid value.
-    // - After `ptr::write`, a valid `T` is located at `*mut_ref`
-    unsafe {
-        let p: *mut T = mut_ref;
-        let old_t = p.read();
-        let new_t = panic::catch_unwind(panic::AssertUnwindSafe(move || transform(old_t)))
-            .unwrap_or_else(|_| panicked_in_transform_mut());
-        p.write(new_t);
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use std::borrow::Cow;
-
-    /// A sample message with custom presence bits, meant to mirror a C++
-    /// message.
-    #[derive(Default, Debug)]
-    struct MyMessage {
-        /// has a default of `0`
-        a: i32,
-
-        /// has a default of `5`
-        b: i32,
-
-        /// Packed presence bitfield for `a` and `b`
-        presence: u8,
-    }
-
-    impl MyMessage {
-        fn a(&self) -> View<'_, VtableProxied> {
-            VtableProxiedView { val: get_a(self) }
-        }
-
-        fn a_opt(&self) -> Optional<View<'_, VtableProxied>> {
-            Optional::new(self.a(), has_a(self))
-        }
-
-        fn a_mut(&mut self) -> FieldEntry<'_, VtableProxied> {
-            static A_VTABLE: ProxyVtable =
-                ProxyVtable { get: get_a, set: set_a, clear: clear_a, has: has_a };
-            make_field_entry(self, &A_VTABLE)
-        }
-
-        fn b(&self) -> View<'_, VtableProxied> {
-            VtableProxiedView { val: get_b(self) }
-        }
-
-        fn b_opt(&self) -> Optional<View<'_, VtableProxied>> {
-            Optional::new(self.b(), has_b(self))
-        }
-
-        fn b_mut(&mut self) -> FieldEntry<'_, VtableProxied> {
-            static B_VTABLE: ProxyVtable =
-                ProxyVtable { get: get_b, set: set_b, clear: clear_b, has: has_b };
-            make_field_entry(self, &B_VTABLE)
-        }
-    }
-
-    fn make_field_entry<'msg>(
-        msg: &'msg mut MyMessage,
-        vtable: &'msg ProxyVtable,
-    ) -> FieldEntry<'msg, VtableProxied> {
-        if (vtable.has)(&*msg) {
-            Optional::Set(PresentField::from_inner(Private, VtableProxiedMut { msg, vtable }))
-        } else {
-            Optional::Unset(AbsentField::from_inner(Private, VtableProxiedMut { msg, vtable }))
-        }
-    }
-
-    // Thunks used for the vtable. For a C++ message these would be defined in C++
-    // and exported via a C API
-    const A_BIT: u8 = 0;
-    const B_BIT: u8 = 1;
-
-    fn get_a(msg: &MyMessage) -> i32 {
-        if has_a(msg) { msg.a } else { 0 }
-    }
-
-    fn get_b(msg: &MyMessage) -> i32 {
-        if has_b(msg) { msg.b } else { 5 }
-    }
-
-    fn set_a(msg: &mut MyMessage, val: i32) {
-        msg.presence |= (1 << A_BIT);
-        msg.a = val;
-    }
-
-    fn set_b(msg: &mut MyMessage, val: i32) {
-        msg.presence |= (1 << B_BIT);
-        msg.b = val;
-    }
-
-    fn clear_a(msg: &mut MyMessage) {
-        msg.presence &= !(1 << A_BIT);
-    }
-
-    fn clear_b(msg: &mut MyMessage) {
-        msg.presence &= !(1 << B_BIT);
-    }
-
-    fn has_a(msg: &MyMessage) -> bool {
-        msg.presence & (1 << A_BIT) != 0
-    }
-
-    fn has_b(msg: &MyMessage) -> bool {
-        msg.presence & (1 << B_BIT) != 0
-    }
-
-    #[derive(Debug)]
-    struct ProxyVtable {
-        get: fn(&MyMessage) -> i32,
-        set: fn(&mut MyMessage, val: i32),
-        clear: fn(&mut MyMessage),
-        has: fn(&MyMessage) -> bool,
-    }
-
-    /// A proxy for a `i32` that is accessed through methods on a vtable.
-    struct VtableProxied;
-
-    impl Proxied for VtableProxied {
-        type View<'msg> = VtableProxiedView;
-        type Mut<'msg> = VtableProxiedMut<'msg>;
-    }
-
-    impl ProxiedWithPresence for VtableProxied {
-        // In this case, the `PresentMutData` and `AbsentMutData` are identical to the
-        // `Mut` in layout. Other types/runtimes could require otherwise, e.g. `Mut`
-        // could be defined to only have get/set functions in its vtable, and not
-        // has/clear.
-        type PresentMutData<'msg> = VtableProxiedMut<'msg>;
-        type AbsentMutData<'msg> = VtableProxiedMut<'msg>;
-
-        fn clear_present_field<'msg>(
-            present_mutator: Self::PresentMutData<'msg>,
-        ) -> Self::AbsentMutData<'msg> {
-            (present_mutator.vtable.clear)(&mut *present_mutator.msg);
-            present_mutator
-        }
-
-        fn set_absent_to_default<'msg>(
-            absent_mutator: Self::AbsentMutData<'msg>,
-        ) -> Self::PresentMutData<'msg> {
-            SettableValue::<VtableProxied>::set_on_absent(
-                absent_mutator.as_view().val(),
-                Private,
-                absent_mutator,
-            )
-        }
-    }
-
-    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
-    struct VtableProxiedView {
-        val: i32,
-    }
-
-    impl VtableProxiedView {
-        fn val(&self) -> i32 {
-            self.val
-        }
-
-        fn read(msg: &MyMessage, vtable: &ProxyVtable) -> Self {
-            VtableProxiedView { val: (vtable.get)(msg) }
-        }
-    }
-
-    impl<'msg> ViewProxy<'msg> for VtableProxiedView {
-        type Proxied = VtableProxied;
-
-        fn as_view(&self) -> View<'msg, VtableProxied> {
-            *self
-        }
-
-        fn into_view<'shorter>(self) -> View<'shorter, VtableProxied>
-        where
-            'msg: 'shorter,
-        {
-            self
-        }
-    }
-
-    #[derive(Debug)]
-    struct VtableProxiedMut<'msg> {
-        msg: &'msg mut MyMessage,
-        vtable: &'msg ProxyVtable,
-    }
-
-    impl<'msg> ViewProxy<'msg> for VtableProxiedMut<'msg> {
-        type Proxied = VtableProxied;
-
-        fn as_view(&self) -> View<'_, VtableProxied> {
-            VtableProxiedView::read(self.msg, self.vtable)
-        }
-
-        fn into_view<'shorter>(self) -> View<'shorter, VtableProxied>
-        where
-            'msg: 'shorter,
-        {
-            VtableProxiedView::read(self.msg, self.vtable)
-        }
-    }
-
-    impl<'msg> MutProxy<'msg> for VtableProxiedMut<'msg> {
-        fn as_mut(&mut self) -> Mut<'_, VtableProxied> {
-            VtableProxiedMut { msg: self.msg, vtable: self.vtable }
-        }
-
-        fn into_mut<'shorter>(self) -> Mut<'shorter, VtableProxied>
-        where
-            'msg: 'shorter,
-        {
-            self
-        }
-    }
-
-    impl SettableValue<VtableProxied> for View<'_, VtableProxied> {
-        fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, VtableProxied>)
-        where
-            VtableProxied: 'msg,
-        {
-            SettableValue::<VtableProxied>::set_on(self.val(), Private, mutator)
-        }
-
-        fn set_on_absent<'msg>(
-            self,
-            _private: Private,
-            absent_mutator: <VtableProxied as ProxiedWithPresence>::AbsentMutData<'msg>,
-        ) -> <VtableProxied as ProxiedWithPresence>::PresentMutData<'msg> {
-            SettableValue::<VtableProxied>::set_on_absent(self.val(), Private, absent_mutator)
-        }
-    }
-
-    impl SettableValue<VtableProxied> for i32 {
-        fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, VtableProxied>)
-        where
-            VtableProxied: 'msg,
-        {
-            (mutator.vtable.set)(mutator.msg, self)
-        }
-
-        fn set_on_absent<'msg>(
-            self,
-            _private: Private,
-            absent_mutator: <VtableProxied as ProxiedWithPresence>::AbsentMutData<'msg>,
-        ) -> <VtableProxied as ProxiedWithPresence>::PresentMutData<'msg> {
-            (absent_mutator.vtable.set)(absent_mutator.msg, self);
-            absent_mutator
-        }
-    }
-
-    #[test]
-    fn test_field_entry() {
-        use googletest::prelude::*;
-        let mut m1 = MyMessage::default();
-        let mut m2 = MyMessage::default();
-
-        let mut m1_a = m1.a_mut();
-        assert_that!(m1_a, matches_pattern!(Optional::Unset(_)));
-
-        assert_that!(m1_a.as_view().val(), eq(0));
-
-        assert_that!(m2.b().val(), eq(5));
-
-        let mut m2_b = m2.b_mut();
-        assert_that!(m2_b.is_unset(), eq(true));
-        assert_that!(m2_b.as_view().val(), eq(5));
-
-        m2_b.set(10);
-        assert_that!(m2_b.is_set(), eq(true));
-        assert_that!(m2_b, matches_pattern!(Optional::Set(_)));
-        assert_that!(m2_b.as_view().val(), eq(10));
-
-        assert_that!(m1_a.or_default().as_view().val(), eq(0));
-        assert_that!(m1.a_opt(), eq(Optional::Set(VtableProxiedView { val: 0 })));
-        m1.a_mut().clear();
-
-        assert_that!(m1.a().val(), eq(0));
-        assert_that!(m1.b().val(), eq(5));
-        assert_that!(m2.a().val(), eq(0));
-        assert_that!(m2.b().val(), eq(10));
-    }
-
-    #[test]
-    fn test_or_set() {
-        use googletest::prelude::*;
-        let mut m1 = MyMessage::default();
-        let mut m2 = MyMessage::default();
-
-        assert_that!(m1.a_mut().or_set(10).get().val(), eq(10));
-        assert_that!(m1.a_opt(), eq(Optional::Set(VtableProxiedView { val: 10 })));
-        assert_that!(m1.a_mut().or_set(20).get().val(), eq(10));
-        assert_that!(m1.a_opt(), eq(Optional::Set(VtableProxiedView { val: 10 })));
-
-        assert_that!(m2.a_mut().or_set_with(|| m1.a().val() + m1.b().val()).get().val(), eq(15));
-        assert_that!(m2.a_opt(), eq(Optional::Set(VtableProxiedView { val: 15 })));
-        assert_that!(m2.a_mut().or_set_with(|| None::<i32>.unwrap()).get().val(), eq(15));
-        assert_that!(m2.a_opt(), eq(Optional::Set(VtableProxiedView { val: 15 })));
-    }
-
-    #[test]
-    fn test_into_optional_view() {
-        use googletest::prelude::*;
-        let mut m1 = MyMessage::default();
-        assert_that!(
-            m1.a_mut().into_optional_view(),
-            eq(Optional::Unset(VtableProxiedView { val: 0 }))
-        );
-        m1.a_mut().set(10);
-        assert_that!(
-            m1.a_mut().into_optional_view(),
-            eq(Optional::Set(VtableProxiedView { val: 10 }))
-        );
-        assert_that!(
-            m1.b_mut().into_optional_view(),
-            eq(Optional::Unset(VtableProxiedView { val: 5 }))
-        );
-    }
-
-    #[test]
-    fn test_try_into_mut() {
-        use googletest::prelude::*;
-        let mut m1 = MyMessage::default();
-        assert_that!(m1.a_mut().try_into_mut().is_none(), eq(true));
-        m1.a_mut().set(10);
-        let mut a_mut = m1.a_mut().try_into_mut().expect("field to be set");
-        a_mut.set(20);
-        assert_that!(m1.a().val(), eq(20));
-    }
-
-    #[test]
-    fn test_present_field() {
-        use googletest::prelude::*;
-        let mut m = MyMessage::default();
-        m.a_mut().set(10);
-        match m.a_mut() {
-            Optional::Set(mut present) => {
-                assert_that!(present.as_view().val(), eq(10));
-                present.set(20);
-                assert_that!(present.as_view().val(), eq(20));
-                present.into_mut().set(30);
-            }
-            Optional::Unset(_) => unreachable!(),
-        }
-        assert_that!(m.a_opt(), eq(Optional::Set(VtableProxiedView { val: 30 })));
-        m.b_mut().set(20);
-        match m.b_mut() {
-            Optional::Set(present) => present.clear(),
-            Optional::Unset(_) => unreachable!(),
-        };
-        assert_that!(m.b_opt(), eq(Optional::Unset(VtableProxiedView { val: 5 })));
-    }
-
-    #[test]
-    fn test_absent_field() {
-        use googletest::prelude::*;
-        let mut m = MyMessage::default();
-        match m.a_mut() {
-            Optional::Set(_) => unreachable!(),
-            Optional::Unset(absent) => {
-                assert_that!(absent.as_view().val(), eq(0));
-                absent.set(20);
-            }
-        }
-        assert_that!(m.a_opt(), eq(Optional::Set(VtableProxiedView { val: 20 })));
-        match m.b_mut() {
-            Optional::Set(_) => unreachable!(),
-            Optional::Unset(absent) => {
-                assert_that!(absent.as_view().val(), eq(5));
-                absent.set_default();
-            }
-        }
-        assert_that!(m.b_opt(), eq(Optional::Set(VtableProxiedView { val: 5 })));
-    }
-}
diff --git a/rust/primitive.rs b/rust/primitive.rs
index 7c34795c9a..75665eca2b 100644
--- a/rust/primitive.rs
+++ b/rust/primitive.rs
@@ -4,101 +4,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
-
-use std::fmt::Debug;
-
-use crate::__internal::Private;
-use crate::__runtime::InnerPrimitiveMut;
-use crate::vtable::{PrimitiveWithRawVTable, ProxiedWithRawVTable, RawVTableOptionalMutatorData};
-use crate::{Mut, MutProxy, Proxied, ProxiedWithPresence, SettableValue, View, ViewProxy};
-
-/// A mutator for a primitive (numeric or enum) value of `T`.
-///
-/// This type is `protobuf::Mut<'msg, T>`.
-pub struct PrimitiveMut<'msg, T> {
-    inner: InnerPrimitiveMut<'msg, T>,
-}
-
-impl<'msg, T> Debug for PrimitiveMut<'msg, T>
-where
-    T: PrimitiveWithRawVTable,
-{
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        f.debug_struct("PrimitiveMut").field("inner", &self.inner).finish()
-    }
-}
-
-impl<'msg, T> PrimitiveMut<'msg, T> {
-    /// # Safety
-    /// `inner` must be valid and non-aliased for `T` for `'msg`
-    #[doc(hidden)]
-    pub unsafe fn from_inner(_private: Private, inner: InnerPrimitiveMut<'msg, T>) -> Self {
-        Self { inner }
-    }
-}
-
-// SAFETY: all `T` that can perform mutations don't mutate through a shared
-// reference.
-unsafe impl<'msg, T> Sync for PrimitiveMut<'msg, T> {}
-
-impl<'msg, T> PrimitiveMut<'msg, T>
-where
-    T: PrimitiveWithRawVTable,
-{
-    /// Gets the current value of the field.
-    pub fn get(&self) -> View<'_, T> {
-        T::make_view(Private, self.inner)
-    }
-
-    /// Sets a new value for the field.
-    pub fn set(&mut self, val: impl SettableValue<T>) {
-        val.set_on(Private, self.as_mut())
-    }
-
-    #[doc(hidden)]
-    pub fn set_primitive(&mut self, _private: Private, value: T) {
-        // SAFETY: the raw mutator is valid for `'msg` as enforced by `Mut`
-        unsafe { self.inner.set(value) }
-    }
-}
-
-impl<'msg, T> ViewProxy<'msg> for PrimitiveMut<'msg, T>
-where
-    T: PrimitiveWithRawVTable,
-{
-    type Proxied = T;
-
-    fn as_view(&self) -> View<'_, Self::Proxied> {
-        self.get()
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, Self::Proxied> {
-        self.get()
-    }
-}
-
-impl<'msg, T> MutProxy<'msg> for PrimitiveMut<'msg, T>
-where
-    T: PrimitiveWithRawVTable,
-{
-    fn as_mut(&mut self) -> Mut<'_, Self::Proxied> {
-        PrimitiveMut { inner: self.inner }
-    }
-
-    fn into_mut<'shorter>(self) -> Mut<'shorter, Self::Proxied>
-    where
-        'msg: 'shorter,
-    {
-        self
-    }
-}
+use crate::{Proxied, View, ViewProxy};
 
 macro_rules! impl_singular_primitives {
   ($($t:ty),*) => {
       $(
         impl Proxied for $t {
             type View<'msg> = $t;
-            type Mut<'msg> = PrimitiveMut<'msg, $t>;
         }
 
         impl<'msg> ViewProxy<'msg> for $t {
@@ -113,40 +25,6 @@ macro_rules! impl_singular_primitives {
             }
         }
 
-        impl SettableValue<$t> for $t {
-            fn set_on<'msg>(self, private: Private, mut mutator: Mut<'msg, $t>) where $t: 'msg {
-                mutator.set_primitive(private, self)
-            }
-
-            fn set_on_absent(
-                self,
-                _private: Private,
-                absent_mutator: <$t as ProxiedWithPresence>::PresentMutData<'_>,
-            ) -> <$t as ProxiedWithPresence>::AbsentMutData<'_>
-            {
-                absent_mutator.set(Private, self)
-            }
-        }
-
-        impl ProxiedWithPresence for $t {
-            type PresentMutData<'msg> = RawVTableOptionalMutatorData<'msg, $t>;
-            type AbsentMutData<'msg> = RawVTableOptionalMutatorData<'msg, $t>;
-
-            fn clear_present_field(
-                present_mutator: Self::PresentMutData<'_>,
-            ) -> Self::AbsentMutData<'_> {
-                present_mutator.clear(Private)
-            }
-
-            fn set_absent_to_default(
-                absent_mutator: Self::AbsentMutData<'_>,
-            ) -> Self::PresentMutData<'_> {
-                absent_mutator.set_absent_to_default(Private)
-            }
-        }
-
-        impl PrimitiveWithRawVTable for $t {}
-
         // ProxiedInRepeated is implemented in {cpp,upb}.rs
       )*
   }
diff --git a/rust/proto_macro.rs b/rust/proto_macro.rs
index d3da607664..95b14232bf 100644
--- a/rust/proto_macro.rs
+++ b/rust/proto_macro.rs
@@ -53,13 +53,13 @@ macro_rules! proto_internal {
     // nested message
     (@msg $msg:ident $submsg:ident : $($msgtype:ident)::+ { $field:ident : $($value:tt)* }) => {
         {
-            let mut $msg: <$($msgtype)::+ as $crate::Proxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
+            let mut $msg: <$($msgtype)::+ as $crate::MutProxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
             proto_internal!(@msg $msg $field : $($value)*);
         }
     };
     (@msg $msg:ident $submsg:ident : ::$($msgtype:ident)::+ { $field:ident : $($value:tt)* }) => {
         {
-            let mut $msg: <::$($msgtype)::+ as $crate::Proxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
+            let mut $msg: <::$($msgtype)::+ as $crate::MutProxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
             proto_internal!(@msg $msg $field : $($value)*);
         }
     };
@@ -77,12 +77,12 @@ macro_rules! proto_internal {
     // empty nested message
     (@msg $msg:ident $submsg:ident : $($msgtype:ident)::+ { }) => {
         {
-            let mut $msg: <$($msgtype)::+ as $crate::Proxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
+            let mut $msg: <$($msgtype)::+ as $crate::MutProxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
         }
     };
     (@msg $msg:ident $submsg:ident : ::$($msgtype:ident)::+ { }) => {
         {
-            let mut $msg: <::$($msgtype)::+ as $crate::Proxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
+            let mut $msg: <::$($msgtype)::+ as $crate::MutProxied>::Mut<'_> = $crate::__internal::paste!($msg.[<$submsg _mut>]());
         }
     };
 
diff --git a/rust/proxied.rs b/rust/proxied.rs
index 8d9214d28e..3d7124813e 100644
--- a/rust/proxied.rs
+++ b/rust/proxied.rs
@@ -44,25 +44,30 @@
 //! implemented the concept of "proxy" types. Proxy types are a reference-like
 //! indirection between the user and the internal memory representation.
 
-use crate::RepeatedMut;
 use crate::__internal::Private;
-use crate::repeated::ProxiedInRepeated;
 use std::fmt::Debug;
 
 /// A type that can be accessed through a reference-like proxy.
 ///
-/// An instance of a `Proxied` can be accessed
-/// immutably via `Proxied::View` and mutably via `Proxied::Mut`.
+/// An instance of a `Proxied` can be accessed immutably via `Proxied::View`.
 ///
 /// All Protobuf field types implement `Proxied`.
 pub trait Proxied {
     /// The proxy type that provides shared access to a `T`, like a `&'msg T`.
     ///
     /// Most code should use the type alias [`View`].
-    type View<'msg>: ViewProxy<'msg, Proxied = Self> + Copy + Send + SettableValue<Self>
+    type View<'msg>: ViewProxy<'msg, Proxied = Self> + Copy + Send
     where
         Self: 'msg;
+}
 
+/// A type that can be be accessed through a reference-like proxy.
+///
+/// An instance of a `MutProxied` can be accessed mutably via `MutProxied::Mut`
+/// and immutably via `MutProxied::View`.
+///
+/// `MutProxied` is implemented by message, map and repeated field types.
+pub trait MutProxied: Proxied {
     /// The proxy type that provides exclusive mutable access to a `T`, like a
     /// `&'msg mut T`.
     ///
@@ -83,7 +88,7 @@ pub type View<'msg, T> = <T as Proxied>::View<'msg>;
 ///
 /// This is more concise than fully spelling the associated type.
 #[allow(dead_code)]
-pub type Mut<'msg, T> = <T as Proxied>::Mut<'msg>;
+pub type Mut<'msg, T> = <T as MutProxied>::Mut<'msg>;
 
 /// Declares conversion operations common to all views.
 ///
@@ -127,7 +132,7 @@ pub trait ViewProxy<'msg>: 'msg + Sync + Unpin + Sized + Debug {
     ///     y: View<'b, T>,
     /// ) -> [View<'b, T>; 2]
     /// where
-    ///     T: Proxied,
+    ///     T: MutProxied,
     ///     'a: 'b,
     /// {
     ///     // `[x, y]` fails to compile because `'a` is not the same as `'b` and the `View`
@@ -147,7 +152,10 @@ pub trait ViewProxy<'msg>: 'msg + Sync + Unpin + Sized + Debug {
 ///
 /// This trait is intentionally made non-object-safe to prevent a potential
 /// future incompatible change.
-pub trait MutProxy<'msg>: ViewProxy<'msg> {
+pub trait MutProxy<'msg>: ViewProxy<'msg>
+where
+    Self::Proxied: MutProxied,
+{
     /// Gets an immutable view of this field. This is shorthand for `as_view`.
     ///
     /// This provides a shorter lifetime than `into_view` but can also be called
@@ -157,13 +165,6 @@ pub trait MutProxy<'msg>: ViewProxy<'msg> {
         self.as_view()
     }
 
-    /// Sets this field to the given `val`.
-    ///
-    /// Any borrowed data from `val` will be cloned.
-    fn set(&mut self, val: impl SettableValue<Self::Proxied>) {
-        val.set_on(Private, self.as_mut())
-    }
-
     /// Converts a borrow into a `Mut` with the lifetime of that borrow.
     ///
     /// This function enables calling multiple methods consuming `self`, for
@@ -206,83 +207,17 @@ pub trait MutProxy<'msg>: ViewProxy<'msg> {
         'msg: 'shorter;
 }
 
-// TODO: move this to `optional.rs` as it's only used for optionals
-/// `Proxied` types that can be optionally set or unset.
+/// A value to `Proxied`-value conversion that consumes the input value.
 ///
-/// All scalar and message types implement `ProxiedWithPresence`, while repeated
-/// types don't.
-pub trait ProxiedWithPresence: Proxied {
-    /// The data necessary to store a present field mutator proxying `Self`.
-    /// This is the contents of `PresentField<'msg, Self>`.
-    type PresentMutData<'msg>: MutProxy<'msg, Proxied = Self>;
-
-    /// The data necessary to store an absent field mutator proxying `Self`.
-    /// This is the contents of `AbsentField<'msg, Self>`.
-    type AbsentMutData<'msg>: ViewProxy<'msg, Proxied = Self>;
-
-    /// Clears a present field.
-    fn clear_present_field(present_mutator: Self::PresentMutData<'_>) -> Self::AbsentMutData<'_>;
-
-    /// Sets an absent field to its default value.
-    ///
-    /// This can be more efficient than setting with a default value, e.g.
-    /// a default submessage could share resources with the parent message.
-    fn set_absent_to_default(absent_mutator: Self::AbsentMutData<'_>) -> Self::PresentMutData<'_>;
-}
-
-/// Values that can be used to set a field of `T`.
-pub trait SettableValue<T>: Sized
-where
-    T: Proxied + ?Sized,
-{
-    /// Consumes `self` to set the given mutator to the value of `self`.
-    #[doc(hidden)]
-    fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, T>)
-    where
-        T: 'msg;
-
-    /// Consumes `self` and `absent_mutator` to set the given empty field to
-    /// the value of `self`.
-    #[doc(hidden)]
-    fn set_on_absent(
-        self,
-        _private: Private,
-        absent_mutator: T::AbsentMutData<'_>,
-    ) -> T::PresentMutData<'_>
-    where
-        T: ProxiedWithPresence,
-    {
-        let mut present = T::set_absent_to_default(absent_mutator);
-        self.set_on(Private, present.as_mut());
-        present
-    }
-
-    /// Consumes `self` and `present_mutator` to set the given present field
-    /// to the value of `self`.
-    #[doc(hidden)]
-    fn set_on_present(self, _private: Private, mut present_mutator: T::PresentMutData<'_>)
-    where
-        T: ProxiedWithPresence,
-    {
-        self.set_on(Private, present_mutator.as_mut())
-    }
-
-    /// Consumes `self` and `repeated_mutator` to set the value at the
-    /// given index to the value of `self`.
-    ///
-    /// # Safety
-    /// `index` must be less than `repeated_mutator.len()`
-    #[doc(hidden)]
-    unsafe fn set_on_repeated_unchecked(
-        self,
-        _private: Private,
-        mut _repeated_mutator: RepeatedMut<T>,
-        _index: usize,
-    ) where
-        T: ProxiedInRepeated,
-    {
-        unimplemented!()
-    }
+/// All setter functions accept types that implement `IntoProxied`. The purpose
+/// of `IntoProxied` is to allow setting arbitrary values on Protobuf fields
+/// with the minimal number of copies.
+///
+/// This trait must not be implemented on types outside the Protobuf codegen and
+/// runtime. We expect it to change in backwards incompatible ways in the
+/// future.
+pub trait IntoProxied<T: Proxied> {
+    fn into(self, _private: Private) -> T;
 }
 
 #[cfg(test)]
@@ -308,6 +243,9 @@ mod tests {
 
     impl Proxied for MyProxied {
         type View<'msg> = MyProxiedView<'msg>;
+    }
+
+    impl MutProxied for MyProxied {
         type Mut<'msg> = MyProxiedMut<'msg>;
     }
 
@@ -369,45 +307,6 @@ mod tests {
         }
     }
 
-    impl SettableValue<MyProxied> for MyProxiedView<'_> {
-        fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, MyProxied>)
-        where
-            MyProxied: 'msg,
-        {
-            mutator.my_proxied_ref.val = self.my_proxied_ref.val.clone();
-        }
-    }
-
-    impl SettableValue<MyProxied> for String {
-        fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, MyProxied>)
-        where
-            MyProxied: 'msg,
-        {
-            mutator.my_proxied_ref.val = self;
-        }
-    }
-
-    impl SettableValue<MyProxied> for &'_ str {
-        fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, MyProxied>)
-        where
-            MyProxied: 'msg,
-        {
-            mutator.my_proxied_ref.val.replace_range(.., self);
-        }
-    }
-
-    impl SettableValue<MyProxied> for Cow<'_, str> {
-        fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, MyProxied>)
-        where
-            MyProxied: 'msg,
-        {
-            match self {
-                Cow::Owned(x) => <String as SettableValue<MyProxied>>::set_on(x, Private, mutator),
-                Cow::Borrowed(x) => <&str as SettableValue<MyProxied>>::set_on(x, Private, mutator),
-            }
-        }
-    }
-
     #[test]
     fn test_as_view() {
         let my_proxied = MyProxied { val: "Hello World".to_string() };
@@ -417,18 +316,6 @@ mod tests {
         assert_that!(my_view.val(), eq(&my_proxied.val));
     }
 
-    #[test]
-    fn test_as_mut() {
-        let mut my_proxied = MyProxied { val: "Hello World".to_string() };
-
-        let mut my_mut = my_proxied.as_mut();
-        my_mut.set("Hello indeed".to_string());
-
-        let val_after_set = my_mut.as_view().val().to_string();
-        assert_that!(my_proxied.val, eq(val_after_set));
-        assert_that!(my_proxied.val, eq("Hello indeed"));
-    }
-
     fn reborrow_mut_into_view<'msg>(x: Mut<'msg, MyProxied>) -> View<'msg, MyProxied> {
         // x.as_view() fails to compile with:
         //   `ERROR: attempt to return function-local borrowed content`
@@ -460,7 +347,7 @@ mod tests {
         y: &'b View<'a, T>,
     ) -> [View<'b, T>; 2]
     where
-        T: Proxied,
+        T: MutProxied,
         'a: 'b,
     {
         // `[x, y]` fails to compile because `'a` is not the same as `'b` and the `View`
@@ -509,7 +396,7 @@ mod tests {
 
     fn reborrow_generic_mut_into_view<'a, 'b, T>(x: Mut<'a, T>, y: View<'b, T>) -> [View<'b, T>; 2]
     where
-        T: Proxied,
+        T: MutProxied,
         'a: 'b,
     {
         [x.into_view(), y]
@@ -529,7 +416,7 @@ mod tests {
 
     fn reborrow_generic_mut_into_mut<'a, 'b, T>(x: Mut<'a, T>, y: Mut<'b, T>) -> [Mut<'b, T>; 2]
     where
-        T: Proxied,
+        T: MutProxied,
         'a: 'b,
     {
         // `[x, y]` fails to compile because `'a` is not the same as `'b` and the `Mut`
@@ -552,17 +439,4 @@ mod tests {
             reborrow_generic_mut_into_mut::<MyProxied>(my_mut, other_mut);
         }
     }
-
-    #[test]
-    fn test_set() {
-        let mut my_proxied = MyProxied::default();
-        my_proxied.as_mut().set("hello");
-        assert_that!(my_proxied.as_view().val(), eq("hello"));
-
-        my_proxied.as_mut().set(String::from("hello2"));
-        assert_that!(my_proxied.as_view().val(), eq("hello2"));
-
-        my_proxied.as_mut().set(Cow::Borrowed("hello3"));
-        assert_that!(my_proxied.as_view().val(), eq("hello3"));
-    }
 }
diff --git a/rust/repeated.rs b/rust/repeated.rs
index 068dd9a5ec..679e279e6b 100644
--- a/rust/repeated.rs
+++ b/rust/repeated.rs
@@ -15,7 +15,7 @@ use std::iter::FusedIterator;
 use std::marker::PhantomData;
 
 use crate::{
-    Mut, MutProxy, Proxied, SettableValue, View, ViewProxy,
+    IntoProxied, Mut, MutProxied, MutProxy, Proxied, View, ViewProxy,
     __internal::Private,
     __runtime::{InnerRepeated, InnerRepeatedMut, RawRepeatedField},
 };
@@ -61,6 +61,7 @@ impl<'msg, T: ?Sized> Debug for RepeatedMut<'msg, T> {
 #[doc(hidden)]
 impl<'msg, T: ?Sized> RepeatedView<'msg, T> {
     #[doc(hidden)]
+    #[inline]
     pub fn as_raw(&self, _private: Private) -> RawRepeatedField {
         self.raw
     }
@@ -68,6 +69,7 @@ impl<'msg, T: ?Sized> RepeatedView<'msg, T> {
     /// # Safety
     /// - `inner` must be valid to read from for `'msg`
     #[doc(hidden)]
+    #[inline]
     pub unsafe fn from_raw(_private: Private, raw: RawRepeatedField) -> Self {
         Self { raw, _phantom: PhantomData }
     }
@@ -78,11 +80,13 @@ where
     T: ProxiedInRepeated + ?Sized + 'msg,
 {
     /// Gets the length of the repeated field.
+    #[inline]
     pub fn len(&self) -> usize {
         T::repeated_len(*self)
     }
 
     /// Returns true if the repeated field has no values.
+    #[inline]
     pub fn is_empty(&self) -> bool {
         self.len() == 0
     }
@@ -90,6 +94,7 @@ where
     /// Gets the value at `index`.
     ///
     /// Returns `None` if `index > len`.
+    #[inline]
     pub fn get(self, index: usize) -> Option<View<'msg, T>> {
         if index >= self.len() {
             return None;
@@ -102,6 +107,7 @@ where
     ///
     /// # Safety
     /// Undefined behavior if `index >= len`
+    #[inline]
     pub unsafe fn get_unchecked(self, index: usize) -> View<'msg, T> {
         // SAFETY: in-bounds as promised
         unsafe { T::repeated_get_unchecked(self, index) }
@@ -120,11 +126,13 @@ impl<'msg, T: ?Sized> RepeatedMut<'msg, T> {
     /// - There must be no aliasing references or mutations on the same
     ///   underlying object.
     #[doc(hidden)]
+    #[inline]
     pub unsafe fn from_inner(_private: Private, inner: InnerRepeatedMut<'msg>) -> Self {
         Self { inner, _phantom: PhantomData }
     }
 
     #[doc(hidden)]
+    #[inline]
     pub fn as_raw(&mut self, _private: Private) -> RawRepeatedField {
         self.inner.raw
     }
@@ -135,11 +143,13 @@ where
     T: ProxiedInRepeated + ?Sized + 'msg,
 {
     /// Gets the length of the repeated field.
+    #[inline]
     pub fn len(&self) -> usize {
         self.as_view().len()
     }
 
     /// Returns true if the repeated field has no values.
+    #[inline]
     pub fn is_empty(&self) -> bool {
         self.len() == 0
     }
@@ -147,6 +157,7 @@ where
     /// Gets the value at `index`.
     ///
     /// Returns `None` if `index > len`.
+    #[inline]
     pub fn get(&self, index: usize) -> Option<View<T>> {
         self.as_view().get(index)
     }
@@ -155,12 +166,14 @@ where
     ///
     /// # Safety
     /// Undefined behavior if `index >= len`
+    #[inline]
     pub unsafe fn get_unchecked(&self, index: usize) -> View<T> {
         // SAFETY: in-bounds as promised
         unsafe { self.as_view().get_unchecked(index) }
     }
 
     /// Appends `val` to the end of the repeated field.
+    #[inline]
     pub fn push(&mut self, val: View<T>) {
         // TODO: b/320936046 - Use SettableValue instead of View for added ergonomics.
         T::repeated_push(self.as_mut(), val);
@@ -170,6 +183,7 @@ where
     ///
     /// # Panics
     /// Panics if `index >= len`
+    #[inline]
     pub fn set(&mut self, index: usize, val: View<T>) {
         let len = self.len();
         if index >= len {
@@ -184,6 +198,7 @@ where
     ///
     /// # Safety
     /// Undefined behavior if `index >= len`
+    #[inline]
     pub unsafe fn set_unchecked(&mut self, index: usize, val: View<T>) {
         // TODO: b/320936046 - Use SettableValue instead of View for added ergonomics.
         // SAFETY: `index` is in-bounds as promised by the caller.
@@ -208,6 +223,49 @@ where
     }
 }
 
+impl<T> Repeated<T>
+where
+    T: ?Sized + ProxiedInRepeated,
+{
+    pub fn as_view(&self) -> View<Repeated<T>> {
+        RepeatedView { raw: self.inner.raw(), _phantom: PhantomData }
+    }
+
+    #[doc(hidden)]
+    pub fn inner(&self, _private: Private) -> &InnerRepeated {
+        &self.inner
+    }
+}
+
+impl<T> IntoProxied<Repeated<T>> for Repeated<T>
+where
+    T: ?Sized + ProxiedInRepeated,
+{
+    fn into(self, _private: Private) -> Repeated<T> {
+        self
+    }
+}
+
+impl<'msg, T> IntoProxied<Repeated<T>> for RepeatedView<'msg, T>
+where
+    T: 'msg + ?Sized + ProxiedInRepeated,
+{
+    fn into(self, _private: Private) -> Repeated<T> {
+        let mut repeated: Repeated<T> = Repeated::new();
+        T::repeated_copy_from(self, repeated.as_mut());
+        repeated
+    }
+}
+
+impl<'msg, T> IntoProxied<Repeated<T>> for RepeatedMut<'msg, T>
+where
+    T: 'msg + ?Sized + ProxiedInRepeated,
+{
+    fn into(self, _private: Private) -> Repeated<T> {
+        IntoProxied::into(self.as_view(), _private)
+    }
+}
+
 /// Types that can appear in a `Repeated<T>`.
 ///
 /// This trait is implemented by generated code to communicate how the proxied
@@ -253,6 +311,10 @@ pub unsafe trait ProxiedInRepeated: Proxied {
 
     /// Copies the values in the `src` repeated field into `dest`.
     fn repeated_copy_from(src: View<Repeated<Self>>, dest: Mut<Repeated<Self>>);
+
+    /// Ensures that the repeated field has enough space allocated to insert at
+    /// least `additional` values without an allocation.
+    fn repeated_reserve(repeated: Mut<Repeated<Self>>, additional: usize);
 }
 
 /// An iterator over the values inside of a [`View<Repeated<T>>`](RepeatedView).
@@ -275,7 +337,7 @@ impl<'msg, T: ?Sized> Debug for RepeatedIter<'msg, T> {
 /// Users will generally write [`View<Repeated<T>>`](RepeatedView) or
 /// [`Mut<Repeated<T>>`](RepeatedMut) to access the repeated elements
 pub struct Repeated<T: ?Sized + ProxiedInRepeated> {
-    inner: InnerRepeated,
+    pub(crate) inner: InnerRepeated,
     _phantom: PhantomData<T>,
 }
 
@@ -314,6 +376,12 @@ where
     T: ProxiedInRepeated + ?Sized,
 {
     type View<'msg> = RepeatedView<'msg, T> where Repeated<T>: 'msg;
+}
+
+impl<T> MutProxied for Repeated<T>
+where
+    T: ProxiedInRepeated + ?Sized,
+{
     type Mut<'msg> = RepeatedMut<'msg, T> where Repeated<T>: 'msg;
 }
 
@@ -323,10 +391,12 @@ where
 {
     type Proxied = Repeated<T>;
 
+    #[inline]
     fn as_view(&self) -> View<'_, Self::Proxied> {
         *self
     }
 
+    #[inline]
     fn into_view<'shorter>(self) -> View<'shorter, Self::Proxied>
     where
         'msg: 'shorter,
@@ -341,10 +411,12 @@ where
 {
     type Proxied = Repeated<T>;
 
+    #[inline]
     fn as_view(&self) -> View<'_, Self::Proxied> {
         RepeatedView { raw: self.inner.raw, _phantom: PhantomData }
     }
 
+    #[inline]
     fn into_view<'shorter>(self) -> View<'shorter, Self::Proxied>
     where
         'msg: 'shorter,
@@ -357,10 +429,12 @@ impl<'msg, T> MutProxy<'msg> for RepeatedMut<'msg, T>
 where
     T: ProxiedInRepeated + ?Sized + 'msg,
 {
+    #[inline]
     fn as_mut(&mut self) -> Mut<'_, Self::Proxied> {
         RepeatedMut { inner: self.inner, _phantom: PhantomData }
     }
 
+    #[inline]
     fn into_mut<'shorter>(self) -> Mut<'shorter, Self::Proxied>
     where
         'msg: 'shorter,
@@ -369,24 +443,13 @@ where
     }
 }
 
-impl<'msg, T> SettableValue<Repeated<T>> for RepeatedView<'msg, T>
-where
-    T: ProxiedInRepeated + ?Sized + 'msg,
-{
-    fn set_on<'b>(self, _private: Private, mutator: Mut<'b, Repeated<T>>)
-    where
-        Repeated<T>: 'b,
-    {
-        T::repeated_copy_from(self, mutator)
-    }
-}
-
 impl<'msg, T> iter::Iterator for RepeatedIter<'msg, T>
 where
     T: ProxiedInRepeated + ?Sized + 'msg,
 {
     type Item = View<'msg, T>;
 
+    #[inline]
     fn next(&mut self) -> Option<Self::Item> {
         let val = self.view.get(self.current_index);
         if val.is_some() {
@@ -452,6 +515,8 @@ where
     ViewT: Into<View<'view, T>>,
 {
     fn extend<I: IntoIterator<Item = ViewT>>(&mut self, iter: I) {
+        let iter = iter.into_iter();
+        T::repeated_reserve(self.as_mut(), iter.size_hint().0);
         for item in iter {
             self.push(item.into());
         }
@@ -485,8 +550,7 @@ mod tests {
                     assert_that!(r.len(), eq(expected_len));
 
                 )*
-                assert_that!(
-                    r.iter().collect::<Vec<$t>>(), elements_are![$(eq($vals)),*]);
+                assert_that!(r, elements_are![$(eq($vals)),*]);
                 r.set(0, <$t as Default>::default());
                 assert_that!(r.get(0).expect("elem 0"), eq(<$t as Default>::default()));
 
@@ -513,15 +577,12 @@ mod tests {
         assert_that!(r.as_mut().len(), eq(0));
 
         r.as_mut().extend([0, 1]);
-        assert_that!(r.as_mut().iter().collect::<Vec<_>>(), elements_are![eq(0), eq(1)]);
+        assert_that!(r.as_mut(), elements_are![eq(0), eq(1)]);
         let mut x = Repeated::<i32>::new();
         x.as_mut().extend([2, 3]);
 
         r.as_mut().extend(&x.as_mut());
 
-        assert_that!(
-            r.as_mut().iter().collect::<Vec<_>>(),
-            elements_are![eq(0), eq(1), eq(2), eq(3)]
-        );
+        assert_that!(r.as_mut(), elements_are![eq(0), eq(1), eq(2), eq(3)]);
     }
 }
diff --git a/rust/shared.rs b/rust/shared.rs
index 531d4d4e82..9c839fa47a 100644
--- a/rust/shared.rs
+++ b/rust/shared.rs
@@ -22,18 +22,15 @@ use std::fmt;
 /// These are the items protobuf users can access directly.
 #[doc(hidden)]
 pub mod __public {
-    pub use crate::r#enum::UnknownEnumValue;
+    pub use crate::r#enum::{Enum, UnknownEnumValue};
     pub use crate::map::{Map, MapIter, MapMut, MapView, ProxiedInMapValue};
-    pub use crate::optional::{AbsentField, FieldEntry, Optional, PresentField};
-    pub use crate::primitive::PrimitiveMut;
+    pub use crate::optional::Optional;
     pub use crate::proto;
-    pub use crate::proxied::{
-        Mut, MutProxy, Proxied, ProxiedWithPresence, SettableValue, View, ViewProxy,
-    };
+    pub use crate::proxied::{IntoProxied, Mut, MutProxied, MutProxy, Proxied, View, ViewProxy};
     pub use crate::repeated::{
         ProxiedInRepeated, Repeated, RepeatedIter, RepeatedMut, RepeatedView,
     };
-    pub use crate::string::{BytesMut, ProtoStr, ProtoStrMut};
+    pub use crate::string::ProtoStr;
     pub use crate::ParseError;
 }
 pub use __public::*;
@@ -56,7 +53,6 @@ pub mod __runtime;
 
 #[path = "enum.rs"]
 mod r#enum;
-mod macros;
 mod map;
 mod optional;
 mod primitive;
@@ -64,7 +60,6 @@ mod proto_macro;
 mod proxied;
 mod repeated;
 mod string;
-mod vtable;
 
 /// An error that happened during deserialization.
 #[derive(Debug, Clone)]
diff --git a/rust/string.rs b/rust/string.rs
index a6277d4b79..9272c8d0f0 100644
--- a/rust/string.rs
+++ b/rust/string.rs
@@ -10,14 +10,8 @@
 #![allow(unused)]
 
 use crate::__internal::Private;
-use crate::__runtime::{
-    BytesAbsentMutData, BytesPresentMutData, InnerBytesMut, PtrAndLen, RawMessage,
-};
-use crate::macros::impl_forwarding_settable_value;
-use crate::{
-    AbsentField, FieldEntry, Mut, MutProxy, Optional, PresentField, Proxied, ProxiedWithPresence,
-    SettableValue, View, ViewProxy,
-};
+use crate::__runtime::{PtrAndLen, RawMessage};
+use crate::{Mut, MutProxied, MutProxy, Optional, Proxied, View, ViewProxy};
 use std::borrow::Cow;
 use std::cmp::{Eq, Ord, Ordering, PartialEq, PartialOrd};
 use std::convert::{AsMut, AsRef};
@@ -27,116 +21,8 @@ use std::iter;
 use std::ops::{Deref, DerefMut};
 use utf8::Utf8Chunks;
 
-/// A mutator for `bytes` fields - this type is `protobuf::Mut<'msg, [u8]>`.
-///
-/// This type implements `Deref<Target = [u8]>`, so many operations are
-/// provided through that, including indexing and slicing.
-///
-/// Conceptually, this type is like a `&'msg mut &'msg str`, though the actual
-/// implementation is dependent on runtime and `'msg` is covariant.
-///
-/// Unlike `Vec<u8>`, this type has no in-place concatenation functions like
-/// `extend_from_slice`.
-///
-/// `BytesMut` is not intended to be grown and reallocated like a `Vec`. It's
-/// recommended to instead build a `Vec<u8>` or `String` and pass that directly
-/// to `set`, which will reuse the allocation if supported by the runtime.
-#[derive(Debug)]
-pub struct BytesMut<'msg> {
-    inner: InnerBytesMut<'msg>,
-}
-
-// SAFETY:
-// - Protobuf Rust messages don't allow shared mutation across threads.
-// - Protobuf Rust messages don't share arenas.
-// - All access that touches an arena occurs behind a `&mut`.
-// - All mutators that store an arena are `!Send`.
-unsafe impl Sync for BytesMut<'_> {}
-
-impl<'msg> BytesMut<'msg> {
-    /// Constructs a new `BytesMut` from its internal, runtime-dependent part.
-    #[doc(hidden)]
-    pub fn from_inner(_private: Private, inner: InnerBytesMut<'msg>) -> Self {
-        Self { inner }
-    }
-
-    /// Gets the current value of the field.
-    pub fn get(&self) -> &[u8] {
-        self.as_view()
-    }
-
-    /// Sets the byte string to the given `val`, cloning any borrowed data.
-    ///
-    /// This method accepts both owned and borrowed byte strings; if the runtime
-    /// supports it, an owned value will not reallocate when setting the
-    /// string.
-    pub fn set(&mut self, val: impl SettableValue<[u8]>) {
-        val.set_on(Private, MutProxy::as_mut(self))
-    }
-
-    /// Truncates the byte string.
-    ///
-    /// Has no effect if `new_len` is larger than the current `len`.
-    pub fn truncate(&mut self, new_len: usize) {
-        self.inner.truncate(new_len)
-    }
-
-    /// Clears the byte string to the empty string.
-    ///
-    /// # Compared with `FieldEntry::clear`
-    ///
-    /// Note that this is different than marking an `optional bytes` field as
-    /// absent; if these `bytes` are in an `optional`, `FieldEntry::is_set`
-    /// will still return `true` after this method is invoked.
-    ///
-    /// This also means that if the field has a non-empty default,
-    /// `BytesMut::clear` results in the accessor returning an empty string
-    /// while `FieldEntry::clear` results in the non-empty default.
-    ///
-    /// However, for a proto3 `bytes` that has implicit presence, there is no
-    /// distinction between these states: unset `bytes` is the same as empty
-    /// `bytes` and the default is always the empty string.
-    ///
-    /// In the C++ API, this is the difference between `msg.clear_bytes_field()`
-    /// and `msg.mutable_bytes_field()->clear()`.
-    ///
-    /// Having the same name and signature as `FieldEntry::clear` makes code
-    /// that calls `field_mut().clear()` easier to migrate from implicit
-    /// to explicit presence.
-    pub fn clear(&mut self) {
-        self.truncate(0);
-    }
-}
-
-impl Deref for BytesMut<'_> {
-    type Target = [u8];
-    fn deref(&self) -> &[u8] {
-        self.as_ref()
-    }
-}
-
-impl AsRef<[u8]> for BytesMut<'_> {
-    fn as_ref(&self) -> &[u8] {
-        unsafe { self.inner.get() }
-    }
-}
-
 impl Proxied for [u8] {
     type View<'msg> = &'msg [u8];
-    type Mut<'msg> = BytesMut<'msg>;
-}
-
-impl ProxiedWithPresence for [u8] {
-    type PresentMutData<'msg> = BytesPresentMutData<'msg>;
-    type AbsentMutData<'msg> = BytesAbsentMutData<'msg>;
-
-    fn clear_present_field(present_mutator: Self::PresentMutData<'_>) -> Self::AbsentMutData<'_> {
-        present_mutator.clear()
-    }
-
-    fn set_absent_to_default(absent_mutator: Self::AbsentMutData<'_>) -> Self::PresentMutData<'_> {
-        absent_mutator.set_absent_to_default()
-    }
 }
 
 impl<'msg> ViewProxy<'msg> for &'msg [u8] {
@@ -154,94 +40,6 @@ impl<'msg> ViewProxy<'msg> for &'msg [u8] {
     }
 }
 
-impl<'msg> ViewProxy<'msg> for BytesMut<'msg> {
-    type Proxied = [u8];
-
-    fn as_view(&self) -> &[u8] {
-        self.as_ref()
-    }
-
-    fn into_view<'shorter>(self) -> &'shorter [u8]
-    where
-        'msg: 'shorter,
-    {
-        self.inner.get()
-    }
-}
-
-impl<'msg> MutProxy<'msg> for BytesMut<'msg> {
-    fn as_mut(&mut self) -> BytesMut<'_> {
-        BytesMut { inner: self.inner }
-    }
-
-    fn into_mut<'shorter>(self) -> BytesMut<'shorter>
-    where
-        'msg: 'shorter,
-    {
-        BytesMut { inner: self.inner }
-    }
-}
-
-impl SettableValue<[u8]> for &'_ [u8] {
-    fn set_on<'msg>(self, _private: Private, mutator: Mut<'msg, [u8]>)
-    where
-        [u8]: 'msg,
-    {
-        // SAFETY: this is a `bytes` field with no restriction on UTF-8.
-        unsafe { mutator.inner.set(self) }
-    }
-
-    fn set_on_absent(
-        self,
-        _private: Private,
-        absent_mutator: <[u8] as ProxiedWithPresence>::AbsentMutData<'_>,
-    ) -> <[u8] as ProxiedWithPresence>::PresentMutData<'_> {
-        // SAFETY: this is a `bytes` field with no restriction on UTF-8.
-        unsafe { absent_mutator.set(self) }
-    }
-
-    fn set_on_present(
-        self,
-        _private: Private,
-        present_mutator: <[u8] as ProxiedWithPresence>::PresentMutData<'_>,
-    ) {
-        // SAFETY: this is a `bytes` field with no restriction on UTF-8.
-        unsafe {
-            present_mutator.set(self);
-        }
-    }
-}
-
-impl<const N: usize> SettableValue<[u8]> for &'_ [u8; N] {
-    // forward to `self[..]`
-    impl_forwarding_settable_value!([u8], self => &self[..]);
-}
-
-impl SettableValue<[u8]> for Vec<u8> {
-    // TODO: Investigate taking ownership of this when allowed by the
-    // runtime.
-    impl_forwarding_settable_value!([u8], self => &self[..]);
-}
-
-impl SettableValue<[u8]> for Cow<'_, [u8]> {
-    // TODO: Investigate taking ownership of this when allowed by the
-    // runtime.
-    impl_forwarding_settable_value!([u8], self => &self[..]);
-}
-
-impl Hash for BytesMut<'_> {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.deref().hash(state)
-    }
-}
-
-impl Eq for BytesMut<'_> {}
-impl<'msg> Ord for BytesMut<'msg> {
-    fn cmp(&self, other: &BytesMut<'msg>) -> Ordering {
-        self.deref().cmp(other.deref())
-    }
-}
-
 /// The bytes were not valid UTF-8.
 #[derive(Debug, PartialEq)]
 pub struct Utf8Error(pub(crate) ());
@@ -465,20 +263,6 @@ impl Ord for ProtoStr {
 
 impl Proxied for ProtoStr {
     type View<'msg> = &'msg ProtoStr;
-    type Mut<'msg> = ProtoStrMut<'msg>;
-}
-
-impl ProxiedWithPresence for ProtoStr {
-    type PresentMutData<'msg> = StrPresentMutData<'msg>;
-    type AbsentMutData<'msg> = StrAbsentMutData<'msg>;
-
-    fn clear_present_field(present_mutator: Self::PresentMutData<'_>) -> Self::AbsentMutData<'_> {
-        StrAbsentMutData(present_mutator.0.clear())
-    }
-
-    fn set_absent_to_default(absent_mutator: Self::AbsentMutData<'_>) -> Self::PresentMutData<'_> {
-        StrPresentMutData(absent_mutator.0.set_absent_to_default())
-    }
 }
 
 impl<'msg> ViewProxy<'msg> for &'msg ProtoStr {
@@ -496,261 +280,27 @@ impl<'msg> ViewProxy<'msg> for &'msg ProtoStr {
     }
 }
 
-/// Non-exported newtype for `ProxiedWithPresence::PresentData`
-#[derive(Debug)]
-pub struct StrPresentMutData<'msg>(BytesPresentMutData<'msg>);
-
-impl<'msg> ViewProxy<'msg> for StrPresentMutData<'msg> {
-    type Proxied = ProtoStr;
-
-    fn as_view(&self) -> View<'_, ProtoStr> {
-        // SAFETY: The `ProtoStr` API guards against non-UTF-8 data. The runtime does
-        // not require `ProtoStr` to be UTF-8 if it could be mutated outside of these
-        // guards, such as through FFI.
-        unsafe { ProtoStr::from_utf8_unchecked(self.0.as_view()) }
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, ProtoStr>
-    where
-        'msg: 'shorter,
-    {
-        // SAFETY: The `ProtoStr` API guards against non-UTF-8 data. The runtime does
-        // not require `ProtoStr` to be UTF-8 if it could be mutated outside of these
-        // guards, such as through FFI.
-        unsafe { ProtoStr::from_utf8_unchecked(self.0.into_view()) }
-    }
-}
-
-impl<'msg> MutProxy<'msg> for StrPresentMutData<'msg> {
-    fn as_mut(&mut self) -> Mut<'_, ProtoStr> {
-        ProtoStrMut { bytes: self.0.as_mut() }
-    }
-
-    fn into_mut<'shorter>(self) -> Mut<'shorter, ProtoStr>
-    where
-        'msg: 'shorter,
-    {
-        ProtoStrMut { bytes: self.0.into_mut() }
-    }
-}
-
-/// Non-exported newtype for `ProxiedWithPresence::AbsentData`
-#[derive(Debug)]
-pub struct StrAbsentMutData<'msg>(BytesAbsentMutData<'msg>);
-
-impl<'msg> ViewProxy<'msg> for StrAbsentMutData<'msg> {
-    type Proxied = ProtoStr;
-
-    fn as_view(&self) -> View<'_, ProtoStr> {
-        // SAFETY: The `ProtoStr` API guards against non-UTF-8 data. The runtime does
-        // not require `ProtoStr` to be UTF-8 if it could be mutated outside of these
-        // guards, such as through FFI.
-        unsafe { ProtoStr::from_utf8_unchecked(self.0.as_view()) }
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, ProtoStr>
-    where
-        'msg: 'shorter,
-    {
-        // SAFETY: The `ProtoStr` API guards against non-UTF-8 data. The runtime does
-        // not require `ProtoStr` to be UTF-8 if it could be mutated outside of these
-        // guards, such as through FFI.
-        unsafe { ProtoStr::from_utf8_unchecked(self.0.into_view()) }
-    }
-}
-
-#[derive(Debug)]
-pub struct ProtoStrMut<'msg> {
-    bytes: BytesMut<'msg>,
-}
-
-impl<'msg> ProtoStrMut<'msg> {
-    /// Constructs a new `ProtoStrMut` from its internal, runtime-dependent
-    /// part.
-    #[doc(hidden)]
-    pub fn from_inner(_private: Private, inner: InnerBytesMut<'msg>) -> Self {
-        Self { bytes: BytesMut { inner } }
-    }
-
-    /// Converts a `bytes` `FieldEntry` into a `string` one. Used by gencode.
-    #[doc(hidden)]
-    pub fn field_entry_from_bytes(
-        _private: Private,
-        field_entry: FieldEntry<'_, [u8]>,
-    ) -> FieldEntry<ProtoStr> {
-        match field_entry {
-            Optional::Set(present) => {
-                Optional::Set(PresentField::from_inner(Private, StrPresentMutData(present.inner)))
-            }
-            Optional::Unset(absent) => {
-                Optional::Unset(AbsentField::from_inner(Private, StrAbsentMutData(absent.inner)))
-            }
-        }
-    }
-
-    /// Gets the current value of the field.
-    pub fn get(&self) -> &ProtoStr {
-        self.as_view()
-    }
-
-    /// Sets the string to the given `val`, cloning any borrowed data.
-    ///
-    /// This method accepts both owned and borrowed strings; if the runtime
-    /// supports it, an owned value will not reallocate when setting the
-    /// string.
-    pub fn set(&mut self, val: impl SettableValue<ProtoStr>) {
-        val.set_on(Private, MutProxy::as_mut(self))
-    }
-
-    /// Truncates the string.
-    ///
-    /// Has no effect if `new_len` is larger than the current `len`.
-    ///
-    /// If `new_len` does not lie on a UTF-8 `char` boundary, behavior is
-    /// runtime-dependent. If this occurs, the runtime may:
-    ///
-    /// - Panic
-    /// - Truncate the string further to be on a `char` boundary.
-    /// - Truncate to `new_len`, resulting in a `ProtoStr` with a non-UTF8 tail.
-    pub fn truncate(&mut self, new_len: usize) {
-        self.bytes.truncate(new_len)
-    }
-
-    /// Clears the string, setting it to the empty string.
-    ///
-    /// # Compared with `FieldEntry::clear`
-    ///
-    /// Note that this is different than marking an `optional string` field as
-    /// absent; if this cleared `string` is in an `optional`,
-    /// `FieldEntry::is_set` will still return `true` after this method is
-    /// invoked.
-    ///
-    /// This also means that if the field has a non-empty default,
-    /// `ProtoStrMut::clear` results in the accessor returning an empty string
-    /// while `FieldEntry::clear` results in the non-empty default.
-    ///
-    /// However, for a proto3 `string` that has implicit presence, there is no
-    /// distinction between these states: unset `string` is the same as empty
-    /// `string` and the default is always the empty string.
-    ///
-    /// In the C++ API, this is the difference between
-    /// `msg.clear_string_field()`
-    /// and `msg.mutable_string_field()->clear()`.
-    ///
-    /// Having the same name and signature as `FieldEntry::clear` makes code
-    /// that calls `field_mut().clear()` easier to migrate from implicit
-    /// to explicit presence.
-    pub fn clear(&mut self) {
-        self.truncate(0);
-    }
-}
-
-impl Deref for ProtoStrMut<'_> {
-    type Target = ProtoStr;
-    fn deref(&self) -> &ProtoStr {
-        self.as_view()
-    }
-}
-
-impl AsRef<ProtoStr> for ProtoStrMut<'_> {
+// TODO: remove after IntoProxied has been implemented for
+// ProtoStr.
+impl AsRef<ProtoStr> for String {
     fn as_ref(&self) -> &ProtoStr {
-        self.as_view()
-    }
-}
-
-impl AsRef<[u8]> for ProtoStrMut<'_> {
-    fn as_ref(&self) -> &[u8] {
-        self.as_view().as_bytes()
-    }
-}
-
-impl<'msg> ViewProxy<'msg> for ProtoStrMut<'msg> {
-    type Proxied = ProtoStr;
-
-    fn as_view(&self) -> &ProtoStr {
-        // SAFETY: The `ProtoStr` API guards against non-UTF-8 data. The runtime does
-        // not require `ProtoStr` to be UTF-8 if it could be mutated outside of these
-        // guards, such as through FFI.
-        unsafe { ProtoStr::from_utf8_unchecked(self.bytes.as_view()) }
-    }
-
-    fn into_view<'shorter>(self) -> &'shorter ProtoStr
-    where
-        'msg: 'shorter,
-    {
-        unsafe { ProtoStr::from_utf8_unchecked(self.bytes.into_view()) }
+        ProtoStr::from_str(self.as_str())
     }
 }
 
-impl<'msg> MutProxy<'msg> for ProtoStrMut<'msg> {
-    fn as_mut(&mut self) -> ProtoStrMut<'_> {
-        ProtoStrMut { bytes: BytesMut { inner: self.bytes.inner } }
-    }
-
-    fn into_mut<'shorter>(self) -> ProtoStrMut<'shorter>
-    where
-        'msg: 'shorter,
-    {
-        ProtoStrMut { bytes: BytesMut { inner: self.bytes.inner } }
-    }
-}
-
-impl SettableValue<ProtoStr> for &'_ ProtoStr {
-    fn set_on<'b>(self, _private: Private, mutator: Mut<'b, ProtoStr>)
-    where
-        ProtoStr: 'b,
-    {
-        // SAFETY: A `ProtoStr` has the same UTF-8 validity requirement as the runtime.
-        unsafe { mutator.bytes.inner.set(self.as_bytes()) }
-    }
-
-    fn set_on_absent(
-        self,
-        _private: Private,
-        absent_mutator: <ProtoStr as ProxiedWithPresence>::AbsentMutData<'_>,
-    ) -> <ProtoStr as ProxiedWithPresence>::PresentMutData<'_> {
-        // SAFETY: A `ProtoStr` has the same UTF-8 validity requirement as the runtime.
-        StrPresentMutData(unsafe { absent_mutator.0.set(self.as_bytes()) })
-    }
-
-    fn set_on_present(
-        self,
-        _private: Private,
-        present_mutator: <ProtoStr as ProxiedWithPresence>::PresentMutData<'_>,
-    ) {
-        // SAFETY: A `ProtoStr` has the same UTF-8 validity requirement as the runtime.
-        unsafe {
-            present_mutator.0.set(self.as_bytes());
-        }
-    }
-}
-
-impl SettableValue<ProtoStr> for &'_ str {
-    impl_forwarding_settable_value!(ProtoStr, self => ProtoStr::from_str(self));
-}
-
-impl SettableValue<ProtoStr> for String {
-    // TODO: Investigate taking ownership of this when allowed by the
-    // runtime.
-    impl_forwarding_settable_value!(ProtoStr, self => ProtoStr::from_str(&self));
-}
-
-impl SettableValue<ProtoStr> for Cow<'_, str> {
-    // TODO: Investigate taking ownership of this when allowed by the
-    // runtime.
-    impl_forwarding_settable_value!(ProtoStr, self => ProtoStr::from_str(&self));
-}
-
-impl Hash for ProtoStrMut<'_> {
-    fn hash<H: Hasher>(&self, state: &mut H) {
-        self.deref().hash(state)
+// TODO: remove after IntoProxied has been implemented for
+// ProtoStr.
+impl AsRef<ProtoStr> for &str {
+    fn as_ref(&self) -> &ProtoStr {
+        ProtoStr::from_str(self)
     }
 }
 
-impl Eq for ProtoStrMut<'_> {}
-impl<'msg> Ord for ProtoStrMut<'msg> {
-    fn cmp(&self, other: &ProtoStrMut<'msg>) -> Ordering {
-        self.deref().cmp(other.deref())
+// TODO: remove after IntoProxied has been implemented for
+// ProtoStr.
+impl AsRef<ProtoStr> for &ProtoStr {
+    fn as_ref(&self) -> &ProtoStr {
+        self
     }
 }
 
@@ -776,33 +326,12 @@ macro_rules! impl_bytes_partial_cmp {
 }
 
 impl_bytes_partial_cmp!(
-    // Should `BytesMut` compare with `str` and `ProtoStr[Mut]` with `[u8]`?
-    // `[u8]` and `str` do not compare with each other in the stdlib.
-
-    // `BytesMut` against protobuf types
-    <('a, 'b)> BytesMut<'a> => BytesMut<'b>,
-
-    // `BytesMut` against foreign types
-    <('a)> BytesMut<'a> => [u8],
-    <('a)> [u8] => BytesMut<'a>,
-    <('a, const N: usize)> BytesMut<'a> => [u8; N],
-    <('a, const N: usize)> [u8; N] => BytesMut<'a>,
-
     // `ProtoStr` against protobuf types
     <()> ProtoStr => ProtoStr,
-    <('a)> ProtoStr => ProtoStrMut<'a>,
 
     // `ProtoStr` against foreign types
     <()> ProtoStr => str,
     <()> str => ProtoStr,
-
-    // `ProtoStrMut` against protobuf types
-    <('a, 'b)> ProtoStrMut<'a> => ProtoStrMut<'b>,
-    <('a)> ProtoStrMut<'a> => ProtoStr,
-
-    // `ProtoStrMut` against foreign types
-    <('a)> ProtoStrMut<'a> => str,
-    <('a)> str => ProtoStrMut<'a>,
 );
 
 #[cfg(test)]
diff --git a/rust/test/BUILD b/rust/test/BUILD
index d0e86bb03f..898bb075bc 100644
--- a/rust/test/BUILD
+++ b/rust/test/BUILD
@@ -1,4 +1,3 @@
-load("//bazel:cc_proto_library.bzl", "cc_proto_library")
 load(
     "//rust:defs.bzl",
     "rust_cc_proto_library",
@@ -224,17 +223,11 @@ proto_library(
     ],
 )
 
-cc_proto_library(
-    name = "import_public_cc_proto",
-    testonly = True,
-    deps = [":import_public_proto"],
-)
-
 rust_cc_proto_library(
     name = "import_public_cc_rust_proto",
     testonly = True,
     visibility = ["//rust/test/shared:__subpackages__"],
-    deps = [":import_public_cc_proto"],
+    deps = [":import_public_proto"],
 )
 
 rust_upb_proto_library(
@@ -328,37 +321,31 @@ rust_upb_proto_library(
     deps = [":package_disabiguation_proto"],
 )
 
-cc_proto_library(
-    name = "package_disabiguation_cc_proto",
-    testonly = True,
-    deps = [":package_disabiguation_proto"],
-)
-
 rust_cc_proto_library(
     name = "package_disabiguation_cc_rust_proto",
     testonly = True,
     visibility = ["//rust/test/shared:__subpackages__"],
-    deps = [":package_disabiguation_cc_proto"],
+    deps = [":package_disabiguation_proto"],
 )
 
 proto_library(
-    name = "reserved_proto",
+    name = "bad_names_proto",
     testonly = True,
-    srcs = ["reserved.proto"],
+    srcs = ["bad_names.proto"],
 )
 
 rust_cc_proto_library(
-    name = "reserved_cc_rust_proto",
+    name = "bad_names_cc_rust_proto",
     testonly = True,
     visibility = ["//rust/test/shared:__subpackages__"],
-    deps = [":reserved_proto"],
+    deps = [":bad_names_proto"],
 )
 
 rust_upb_proto_library(
-    name = "reserved_upb_rust_proto",
+    name = "bad_names_upb_rust_proto",
     testonly = True,
     visibility = ["//rust/test/shared:__subpackages__"],
-    deps = [":reserved_proto"],
+    deps = [":bad_names_proto"],
 )
 
 proto_library(
@@ -411,19 +398,13 @@ proto_library(
     srcs = ["struct.proto"],
 )
 
-cc_proto_library(
-    name = "struct_cc_proto",
-    testonly = True,
-    deps = [":struct"],
-)
-
 rust_cc_proto_library(
     name = "struct_cc_rust_proto",
     testonly = True,
     visibility = [
         "//rust/test/shared:__subpackages__",
     ],
-    deps = [":struct_cc_proto"],
+    deps = [":struct"],
 )
 
 rust_upb_proto_library(
@@ -441,19 +422,13 @@ proto_library(
     srcs = ["imported_types.proto"],
 )
 
-cc_proto_library(
-    name = "imported_types_cc_proto",
-    testonly = True,
-    deps = [":imported_types_proto"],
-)
-
 rust_cc_proto_library(
     name = "imported_types_cc_rust_proto",
     testonly = True,
     visibility = [
         "//rust/test/shared:__subpackages__",
     ],
-    deps = [":imported_types_cc_proto"],
+    deps = [":imported_types_proto"],
 )
 
 rust_upb_proto_library(
@@ -473,19 +448,13 @@ proto_library(
     deps = [":imported_types_proto"],
 )
 
-cc_proto_library(
-    name = "fields_with_imported_types_cc_proto",
-    testonly = True,
-    deps = [":fields-with-imported-types_proto"],
-)
-
 rust_cc_proto_library(
     name = "fields_with_imported_types_cc_rust_proto",
     testonly = True,
     visibility = [
         "//rust/test/shared:__subpackages__",
     ],
-    deps = [":fields_with_imported_types_cc_proto"],
+    deps = [":fields-with-imported-types_proto"],
 )
 
 rust_upb_proto_library(
diff --git a/rust/test/reserved.proto b/rust/test/bad_names.proto
similarity index 53%
rename from rust/test/reserved.proto
rename to rust/test/bad_names.proto
index 1f8c2a937d..21fbf3b7cb 100644
--- a/rust/test/reserved.proto
+++ b/rust/test/bad_names.proto
@@ -6,8 +6,10 @@
 // https://developers.google.com/open-source/licenses/bsd
 
 // LINT: LEGACY_NAMES
-// The purpose of this file is to be as hostile as possible to reserved words
-// to the Rust language and ensure it still works.
+
+// The purpose of this file is to be hostile on field/message/enum naming and
+// ensure that it works (e.g. collisions between names and language keywords,
+// collisions between two different field's accessor's names).
 
 syntax = "proto2";
 
@@ -36,3 +38,17 @@ message Ref {
     .type.type.Pub.Self const = 3;
   }
 }
+
+// A message where the accessors would collide that should still work. Note that
+// not all collisions problems are avoided, not least because C++ Proto does not
+// avoid all possible collisions (eg a field `x` and `clear_x` will often not
+// compile on C++).
+message AccessorsCollide {
+  message X {}
+  message SetX {}
+  optional SetX set_x = 2;
+  optional X x = 3;
+  oneof o {
+    bool x_mut = 5;
+  }
+}
diff --git a/rust/test/rust_proto_library_unit_test/defs.bzl b/rust/test/rust_proto_library_unit_test/defs.bzl
index 9c4c1ec838..aed8ef4cb3 100644
--- a/rust/test/rust_proto_library_unit_test/defs.bzl
+++ b/rust/test/rust_proto_library_unit_test/defs.bzl
@@ -23,36 +23,12 @@ attach_upb_aspect = rule(
     },
 )
 
-CcAspectHelperInfo = provider(
-    fields = {
-        "rust_proto_info": "RustProtoInfo from the proto_library",
-        "actions_info": "Actions of the proto_library",
-    },
-    doc = "A provider passing data from proto_library through cc_proto_library",
-)
-
-def _cc_aspect_helper_impl(_target, ctx):
-    if ctx.rule.kind == "cc_proto_library":
-        return CcAspectHelperInfo(
-            rust_proto_info = ctx.rule.attr.deps[0][RustProtoInfo],
-            actions_info = ActionsInfo(actions = ctx.rule.attr.deps[0].actions),
-        )
-
-    return []
-
-_cc_aspect_helper = aspect(
-    implementation = _cc_aspect_helper_impl,
-    requires = [rust_cc_proto_library_aspect],
-    attr_aspects = ["deps"],
-)
-
 def _attach_cc_aspect_impl(ctx):
-    helper = ctx.attr.dep[CcAspectHelperInfo]
-    return [helper.rust_proto_info, helper.actions_info]
+    return [ctx.attr.dep[RustProtoInfo], ActionsInfo(actions = ctx.attr.dep.actions)]
 
 attach_cc_aspect = rule(
     implementation = _attach_cc_aspect_impl,
     attrs = {
-        "dep": attr.label(aspects = [_cc_aspect_helper]),
+        "dep": attr.label(aspects = [rust_cc_proto_library_aspect]),
     },
 )
diff --git a/rust/test/rust_proto_library_unit_test/rust_proto_library_unit_test.bzl b/rust/test/rust_proto_library_unit_test/rust_proto_library_unit_test.bzl
index 15e72fd613..610747666b 100644
--- a/rust/test/rust_proto_library_unit_test/rust_proto_library_unit_test.bzl
+++ b/rust/test/rust_proto_library_unit_test/rust_proto_library_unit_test.bzl
@@ -1,7 +1,6 @@
 """This module contains unit tests for rust_proto_library and its aspect."""
 
 load("@bazel_skylib//lib:unittest.bzl", "analysistest", "asserts")
-load("//bazel:cc_proto_library.bzl", "cc_proto_library")
 load("//rust:aspects.bzl", "RustProtoInfo")
 load("//rust:defs.bzl", "rust_cc_proto_library", "rust_upb_proto_library")
 load(":defs.bzl", "ActionsInfo", "attach_cc_aspect", "attach_upb_aspect")
@@ -160,7 +159,7 @@ def _rust_cc_aspect_test_impl(ctx):
 rust_cc_aspect_test = analysistest.make(_rust_cc_aspect_test_impl)
 
 def _test_cc_aspect():
-    attach_cc_aspect(name = "child_proto_with_cc_aspect", dep = ":child_cc_proto")
+    attach_cc_aspect(name = "child_proto_with_cc_aspect", dep = ":child_proto")
 
     rust_cc_aspect_test(
         name = "rust_cc_aspect_test",
@@ -230,7 +229,6 @@ def rust_proto_library_unit_test(name):
         srcs = ["child.proto"],
         deps = [":parent_proto", ":parent2_proto"],
     )
-    cc_proto_library(name = "child_cc_proto", deps = [":child_proto"])
 
     _test_upb_aspect()
     _test_cc_aspect()
diff --git a/rust/test/shared/BUILD b/rust/test/shared/BUILD
index 7210cc2374..fe7eae45dc 100644
--- a/rust/test/shared/BUILD
+++ b/rust/test/shared/BUILD
@@ -14,35 +14,7 @@
 # Once we have a couple of these tests we will investigate ways to remove boilerplate (for example
 # by introducing a build macro that registers 2 rust_test targets).
 
-load("@rules_rust//rust:defs.bzl", "rust_library", "rust_test")
-
-rust_library(
-    name = "matchers_upb",
-    testonly = True,
-    srcs = ["matchers.rs"],
-    aliases = {
-        "//rust:protobuf_upb_export": "protobuf",
-    },
-    visibility = ["//rust/test/shared:__subpackages__"],
-    deps = [
-        "//rust:protobuf_upb_export",
-        "@crate_index//:googletest",
-    ],
-)
-
-rust_library(
-    name = "matchers_cpp",
-    testonly = True,
-    srcs = ["matchers.rs"],
-    aliases = {
-        "//rust:protobuf_cpp_export": "protobuf",
-    },
-    visibility = ["//rust/test/shared:__subpackages__"],
-    deps = [
-        "//rust:protobuf_cpp_export",
-        "@crate_index//:googletest",
-    ],
-)
+load("@rules_rust//rust:defs.bzl", "rust_test")
 
 rust_test(
     name = "child_parent_upb_test",
@@ -159,24 +131,26 @@ rust_test(
 )
 
 rust_test(
-    name = "reserved_cpp_test",
-    srcs = ["reserved_test.rs"],
+    name = "bad_names_cpp_test",
+    srcs = ["bad_names_test.rs"],
     deps = [
-        "//rust/test:reserved_cc_rust_proto",
+        "//rust/test:bad_names_cc_rust_proto",
         "//rust/test:unittest_cc_rust_proto",
         "@crate_index//:googletest",
     ],
 )
 
-rust_test(
-    name = "reserved_upb_test",
-    srcs = ["reserved_test.rs"],
-    deps = [
-        "//rust/test:reserved_upb_rust_proto",
-        "//rust/test:unittest_upb_rust_proto",
-        "@crate_index//:googletest",
-    ],
-)
+# TODO: This test currently fails on upb due to the thunk names not correctly matching
+# the upb C codegen collision avoidance.
+# rust_test(
+#     name = "bad_names_upb_test",
+#     srcs = ["bad_names_test.rs"],
+#     deps = [
+#         "@crate_index//:googletest",
+#         "//rust/test:bad_names_upb_rust_proto",
+#         "//rust/test:unittest_upb_rust_proto",
+#     ],
+# )
 
 rust_test(
     name = "nested_types_cpp_test",
@@ -195,7 +169,6 @@ rust_test(
     srcs = ["accessors_test.rs"],
     aliases = {
         "//rust:protobuf_cpp_export": "protobuf",
-        "//rust/test/shared:matchers_cpp": "matchers",
     },
     proc_macro_deps = [
         "@crate_index//:paste",
@@ -203,7 +176,6 @@ rust_test(
     deps = [
         "//rust:protobuf_cpp_export",
         "//rust/test:unittest_cc_rust_proto",
-        "//rust/test/shared:matchers_cpp",
         "@crate_index//:googletest",
     ],
 )
@@ -213,7 +185,6 @@ rust_test(
     srcs = ["accessors_test.rs"],
     aliases = {
         "//rust:protobuf_upb_export": "protobuf",
-        "//rust/test/shared:matchers_upb": "matchers",
     },
     proc_macro_deps = [
         "@crate_index//:paste",
@@ -221,7 +192,6 @@ rust_test(
     deps = [
         "//rust:protobuf_upb_export",
         "//rust/test:unittest_upb_rust_proto",
-        "//rust/test/shared:matchers_upb",
         "@crate_index//:googletest",
     ],
 )
@@ -231,13 +201,11 @@ rust_test(
     srcs = ["accessors_proto3_test.rs"],
     aliases = {
         "//rust:protobuf_cpp_export": "protobuf",
-        "//rust/test/shared:matchers_cpp": "matchers",
     },
     deps = [
         "//rust:protobuf_cpp_export",
         "//rust/test:unittest_proto3_cc_rust_proto",
         "//rust/test:unittest_proto3_optional_cc_rust_proto",
-        "//rust/test/shared:matchers_cpp",
         "@crate_index//:googletest",
     ],
 )
@@ -247,13 +215,11 @@ rust_test(
     srcs = ["accessors_proto3_test.rs"],
     aliases = {
         "//rust:protobuf_upb_export": "protobuf",
-        "//rust/test/shared:matchers_upb": "matchers",
     },
     deps = [
         "//rust:protobuf_upb_export",
         "//rust/test:unittest_proto3_optional_upb_rust_proto",
         "//rust/test:unittest_proto3_upb_rust_proto",
-        "//rust/test/shared:matchers_upb",
         "@crate_index//:googletest",
     ],
 )
@@ -405,12 +371,10 @@ rust_test(
     srcs = ["proto_macro_test.rs"],
     aliases = {
         "//rust:protobuf_cpp": "protobuf",
-        "//rust/test/shared:matchers_cpp": "matchers",
     },
     deps = [
         "//rust:protobuf_cpp",
         "//rust/test:unittest_cc_rust_proto",
-        "//rust/test/shared:matchers_cpp",
         "@crate_index//:googletest",
     ],
 )
@@ -420,12 +384,10 @@ rust_test(
     srcs = ["proto_macro_test.rs"],
     aliases = {
         "//rust:protobuf_upb": "protobuf",
-        "//rust/test/shared:matchers_upb": "matchers",
     },
     deps = [
         "//rust:protobuf_upb",
         "//rust/test:unittest_upb_rust_proto",
-        "//rust/test/shared:matchers_upb",
         "@crate_index//:googletest",
     ],
 )
diff --git a/rust/test/shared/accessors_map_test.rs b/rust/test/shared/accessors_map_test.rs
index 0fc153f63b..3120bd8f42 100644
--- a/rust/test/shared/accessors_map_test.rs
+++ b/rust/test/shared/accessors_map_test.rs
@@ -24,7 +24,7 @@ macro_rules! generate_map_primitives_tests {
                 let mut msg = TestMap::new();
                 assert_that!(msg.[< map_ $k_field _ $v_field >]().len(), eq(0));
                 assert_that!(
-                    msg.[< map_ $k_field _ $v_field >]().iter().collect::<Vec<_>>(),
+                    msg.[< map_ $k_field _ $v_field >](),
                     elements_are![]
                 );
                 assert_that!(
@@ -41,24 +41,24 @@ macro_rules! generate_map_primitives_tests {
                 assert_that!(msg.[< map_ $k_field _ $v_field _mut>]().insert(k, v), eq(false));
                 assert_that!(msg.[< map_ $k_field _ $v_field >]().len(), eq(1));
                 assert_that!(
-                    msg.[< map_ $k_field _ $v_field >]().iter().collect::<Vec<_>>(),
+                    msg.[< map_ $k_field _ $v_field >](),
                     elements_are![eq((k, v))]
                 );
                 assert_that!(
                     msg.[< map_ $k_field _ $v_field >]().keys().collect::<Vec<_>>(),
-                    elements_are![eq(k)]
+                    elements_are![eq(&k)]
                 );
                 assert_that!(
                     msg.[< map_ $k_field _ $v_field >]().values().collect::<Vec<_>>(),
-                    elements_are![eq(v)]
+                    elements_are![eq(&v)]
                 );
 
                 let k2: $k_type = $k_nonzero;
                 let v2: $v_type = $v_nonzero;
                 assert_that!(msg.[< map_ $k_field _ $v_field _mut>]().insert(k2, v2), eq(true));
-                assert_that!(msg.[< map_ $k_field _ $v_field >]().len(), eq(2));
+                assert_that!(msg.[< map_ $k_field _ $v_field >](), len(eq(2)));
                 assert_that!(
-                    msg.[< map_ $k_field _ $v_field >]().iter().collect::<Vec<_>>(),
+                    msg.[< map_ $k_field _ $v_field >](),
                     unordered_elements_are![
                         eq((k, v)),
                         eq((k2, v2)),
@@ -66,11 +66,11 @@ macro_rules! generate_map_primitives_tests {
                 );
                 assert_that!(
                     msg.[< map_ $k_field _ $v_field >]().keys().collect::<Vec<_>>(),
-                    unordered_elements_are![eq(k), eq(k2)]
+                    unordered_elements_are![eq(&k), eq(&k2)]
                 );
                 assert_that!(
                     msg.[< map_ $k_field _ $v_field >]().values().collect::<Vec<_>>(),
-                    unordered_elements_are![eq(v), eq(v2)]
+                    unordered_elements_are![eq(&v), eq(&v2)]
                 );
             }
         )* }
@@ -105,11 +105,11 @@ fn collect_as_hashmap() {
     let hashmap: HashMap<String, String> =
         msg.map_string_string().iter().map(|(k, v)| (k.to_string(), v.to_string())).collect();
     assert_that!(
-        hashmap.into_iter().collect::<Vec<_>>(),
+        hashmap,
         unordered_elements_are![
-            eq(("hello".to_owned(), "world".to_owned())),
-            eq(("fizz".to_owned(), "buzz".to_owned())),
-            eq(("boo".to_owned(), "blah".to_owned())),
+            (eq("hello"), eq("world")),
+            (eq("fizz"), eq("buzz")),
+            (eq("boo"), eq("blah")),
         ]
     );
 }
@@ -150,11 +150,25 @@ fn test_bytes_and_string_copied() {
     }
 
     assert_that!(msg.map_string_string_mut().get("hello").unwrap(), eq("world"));
+    assert_that!(msg.map_string_string(), unordered_elements_are![(eq("hello"), eq("world"))]);
+    assert_that!(msg.map_int32_bytes_mut().get(1).unwrap(), eq(b"world"));
+}
+
+#[test]
+fn test_map_setter() {
+    let mut msg = TestMap::new();
+    msg.map_string_string_mut().insert("hello", "world");
+    msg.map_string_string_mut().insert("fizz", "buzz");
+
+    let mut msg2 = TestMap::new();
+    msg2.set_map_string_string(msg.map_string_string());
     assert_that!(
-        msg.map_string_string().iter().collect::<Vec<_>>(),
-        unordered_elements_are![eq(("hello".into(), "world".into()))]
+        msg2.map_string_string(),
+        unordered_elements_are![
+            eq(("hello".into(), "world".into())),
+            eq(("fizz".into(), "buzz".into()))
+        ]
     );
-    assert_that!(msg.map_int32_bytes_mut().get(1).unwrap(), eq(b"world"));
 }
 
 macro_rules! generate_map_with_msg_values_tests {
@@ -225,7 +239,7 @@ macro_rules! generate_map_with_msg_values_tests {
                     msg.[< map_ $k_field _all_types_mut >]().remove($k_nonzero),
                     eq(true),
                     "`remove` should return true when key was present.");
-                assert_that!(msg.[< map_ $k_field _all_types >]().len(), eq(0));
+                assert_that!(msg.[< map_ $k_field _all_types >](), empty());
                 assert_that!(
                     msg.[< map_ $k_field _all_types_mut >]().remove($k_nonzero),
                     eq(false),
@@ -238,13 +252,13 @@ macro_rules! generate_map_with_msg_values_tests {
                 //     "`iter` should work when empty."
                 // );
                 assert_that!(
-                    msg.[< map_ $k_field _all_types_mut >]().keys().collect::<Vec<_>>(),
-                    elements_are![],
+                    msg.[< map_ $k_field _all_types_mut >]().keys().count(),
+                    eq(0),
                     "`iter` should work when empty."
                 );
                 assert_that!(
-                    msg.[< map_ $k_field _all_types_mut >]().values().collect::<Vec<_>>(),
-                    elements_are![],
+                    msg.[< map_ $k_field _all_types_mut >]().values().count(),
+                    eq(0),
                     "`iter` should work when empty."
                 );
 
@@ -260,10 +274,10 @@ macro_rules! generate_map_with_msg_values_tests {
                 // );
                 assert_that!(
                     msg.[< map_ $k_field _all_types >]().keys().collect::<Vec<_>>(),
-                    unordered_elements_are![eq($k_nonzero)]
+                    unordered_elements_are![eq(&$k_nonzero)]
                 );
                 assert_that!(
-                    msg.[< map_ $k_field _all_types >]().values().collect::<Vec<_>>().len(),
+                    msg.[< map_ $k_field _all_types >]().values().count(),
                     eq(1));
 
 
@@ -275,15 +289,15 @@ macro_rules! generate_map_with_msg_values_tests {
                     eq(true));
 
                 assert_that!(
-                    msg.[< map_ $k_field _all_types >]().iter().collect::<Vec<_>>().len(),
-                    eq(2)
+                    msg.[< map_ $k_field _all_types >](),
+                    len(eq(2))
                 );
                 assert_that!(
                     msg.[< map_ $k_field _all_types >]().keys().collect::<Vec<_>>(),
-                    unordered_elements_are![eq($k_nonzero), eq($k_other)]
+                    unordered_elements_are![eq(&$k_nonzero), eq(&$k_other)]
                 );
                 assert_that!(
-                    msg.[< map_ $k_field _all_types >]().values().collect::<Vec<_>>().len(),
+                    msg.[< map_ $k_field _all_types >]().values().count(),
                     eq(2)
                 );
             }
diff --git a/rust/test/shared/accessors_repeated_test.rs b/rust/test/shared/accessors_repeated_test.rs
index 9aee4907ea..4c5356a86a 100644
--- a/rust/test/shared/accessors_repeated_test.rs
+++ b/rust/test/shared/accessors_repeated_test.rs
@@ -35,37 +35,38 @@ macro_rules! generate_repeated_numeric_test {
               mutator.set(2, 0 as $t);
 
               assert_that!(
-                  mutator.iter().collect::<Vec<_>>(),
-                  elements_are![eq(2 as $t), eq(1 as $t), eq(0 as $t)]
+                mutator,
+                elements_are![eq(2 as $t), eq(1 as $t), eq(0 as $t)]
               );
               assert_that!(
-                  mutator.as_view().into_iter().collect::<Vec<_>>(),
-                  elements_are![eq(2 as $t), eq(1 as $t), eq(0 as $t)]
+                mutator.as_view(),
+                elements_are![eq(2 as $t), eq(1 as $t), eq(0 as $t)]
               );
 
               for i in 0..mutator.len() {
                   mutator.set(i, 0 as $t);
               }
               assert_that!(
-                  msg.[<repeated_ $field _mut >]().iter().collect::<Vec<_>>(),
-                  each(eq(0 as $t))
+                msg.[<repeated_ $field _mut >](),
+                each(eq(0 as $t))
               );
           }
 
           #[test]
           fn [< test_repeated_ $field _set >]() {
               let mut msg = TestAllTypes::new();
-              let mut mutator = msg.[<repeated_ $field _mut>]();
               let mut msg2 = TestAllTypes::new();
               let mut mutator2 = msg2.[<repeated_ $field _mut>]();
               for i in 0..5 {
                   mutator2.push(i as $t);
               }
-              protobuf::MutProxy::set(&mut mutator, mutator2.as_view());
 
+              msg.[<set_repeated_ $field >](mutator2.as_view());
+
+              let view = msg.[<repeated_ $field>]();
               assert_that!(
-                  mutator.iter().collect::<Vec<_>>(),
-                  eq(mutator2.iter().collect::<Vec<_>>())
+                view.iter().collect::<Vec<_>>(),
+                eq(&mutator2.iter().collect::<Vec<_>>())
               );
           }
 
@@ -124,16 +125,13 @@ fn test_repeated_bool_accessors() {
     mutator.set(2, false);
     assert_that!(mutator.get(2), some(eq(false)));
 
-    assert_that!(mutator.iter().collect::<Vec<_>>(), elements_are![eq(false), eq(true), eq(false)]);
-    assert_that!(
-        mutator.as_view().into_iter().collect::<Vec<_>>(),
-        elements_are![eq(false), eq(true), eq(false)]
-    );
+    assert_that!(mutator, elements_are![eq(false), eq(true), eq(false)]);
+    assert_that!(mutator.as_view(), elements_are![eq(false), eq(true), eq(false)]);
 
     for i in 0..mutator.len() {
         mutator.set(i, false);
     }
-    assert_that!(msg.repeated_bool().iter().collect::<Vec<_>>(), each(eq(false)));
+    assert_that!(msg.repeated_bool(), each(eq(false)));
 }
 
 #[test]
@@ -160,32 +158,33 @@ fn test_repeated_enum_accessors() {
     assert_that!(mutator.get(2), some(eq(NestedEnum::Foo)));
 
     assert_that!(
-        mutator.iter().collect::<Vec<_>>(),
+        mutator,
         elements_are![eq(NestedEnum::Bar), eq(NestedEnum::Baz), eq(NestedEnum::Foo)]
     );
     assert_that!(
-        mutator.as_view().into_iter().collect::<Vec<_>>(),
+        mutator.as_view(),
         elements_are![eq(NestedEnum::Bar), eq(NestedEnum::Baz), eq(NestedEnum::Foo)]
     );
 
     for i in 0..mutator.len() {
         mutator.set(i, NestedEnum::Foo);
     }
-    assert_that!(msg.repeated_nested_enum().iter().collect::<Vec<_>>(), each(eq(NestedEnum::Foo)));
+    assert_that!(msg.repeated_nested_enum(), each(eq(NestedEnum::Foo)));
 }
 
 #[test]
 fn test_repeated_bool_set() {
     let mut msg = TestAllTypes::new();
-    let mut mutator = msg.repeated_bool_mut();
     let mut msg2 = TestAllTypes::new();
     let mut mutator2 = msg2.repeated_bool_mut();
     for _ in 0..5 {
         mutator2.push(true);
     }
-    protobuf::MutProxy::set(&mut mutator, mutator2.as_view());
 
-    assert_that!(mutator.iter().collect::<Vec<_>>(), eq(mutator2.iter().collect::<Vec<_>>()));
+    msg.set_repeated_bool(mutator2.as_view());
+
+    let view = msg.repeated_bool();
+    assert_that!(&view.iter().collect::<Vec<_>>(), eq(&mutator2.iter().collect::<Vec<_>>()));
 }
 
 #[test]
@@ -209,8 +208,8 @@ fn test_repeated_message() {
     assert_that!(msg.repeated_nested_message().get(0).unwrap().bb(), eq(2));
 
     assert_that!(
-        msg.repeated_nested_message().iter().map(|m| m.bb()).collect::<Vec<_>>(),
-        eq(vec![2]),
+        msg.repeated_nested_message(),
+        elements_are![predicate(|m: protobuf::View<NestedMessage>| m.bb() == 2)],
     );
 
     drop(msg);
@@ -241,7 +240,7 @@ fn test_repeated_strings() {
         assert_that!(msg.repeated_string().get(0).unwrap(), eq("set from Mut"));
         assert_that!(msg.repeated_string().get(1).unwrap(), eq("set second str"));
         assert_that!(
-            msg.repeated_string().iter().collect::<Vec<_>>(),
+            msg.repeated_string(),
             elements_are![eq("set from Mut"), eq("set second str")]
         );
         older_msg.repeated_string_mut().copy_from(msg.repeated_string());
@@ -249,7 +248,7 @@ fn test_repeated_strings() {
 
     assert_that!(older_msg.repeated_string().len(), eq(2));
     assert_that!(
-        older_msg.repeated_string().iter().collect::<Vec<_>>(),
+        older_msg.repeated_string(),
         elements_are![eq("set from Mut"), eq("set second str")]
     );
 
diff --git a/rust/test/shared/accessors_test.rs b/rust/test/shared/accessors_test.rs
index fa11b86d07..2c324515be 100644
--- a/rust/test/shared/accessors_test.rs
+++ b/rust/test/shared/accessors_test.rs
@@ -8,7 +8,7 @@
 //! Tests covering accessors for singular bool, int32, int64, and bytes fields.
 
 use googletest::prelude::*;
-use protobuf::{MutProxy, Optional};
+use protobuf::Optional;
 use unittest_proto::{test_all_types, TestAllTypes};
 
 #[test]
@@ -16,7 +16,7 @@ fn test_default_accessors() {
     let msg: TestAllTypes = Default::default();
     assert_that!(
         msg,
-        matches_pattern!(TestAllTypes{
+        matches_pattern!(&TestAllTypes{
             default_int32(): eq(41),
             default_int64(): eq(42),
             default_uint32(): eq(43),
@@ -498,25 +498,16 @@ fn test_nonempty_default_string_accessors() {
 
 #[test]
 fn test_singular_msg_field() {
-    use test_all_types::*;
-
     let mut msg = TestAllTypes::new();
     let msg_view = msg.optional_nested_message();
     // testing reading an int inside a view
     assert_that!(msg_view.bb(), eq(0));
 
     assert_that!(msg.has_optional_nested_message(), eq(false));
-    let mut nested_msg_mut = msg.optional_nested_message_mut();
-
+    let nested_msg_mut = msg.optional_nested_message_mut();
     // test reading an int inside a mut
     assert_that!(nested_msg_mut.bb(), eq(0));
 
-    // Test setting an owned NestedMessage onto another message.
-    let mut new_nested = NestedMessage::new();
-    new_nested.set_bb(7);
-    nested_msg_mut.set(new_nested);
-    assert_that!(nested_msg_mut.bb(), eq(7));
-
     assert_that!(msg.has_optional_nested_message(), eq(true));
 }
 
@@ -762,18 +753,6 @@ fn test_msg_oneof_default_accessors() {
     // TODO: Add tests covering a message-type field in a oneof.
 }
 
-#[test]
-fn test_set_message_from_view() {
-    use protobuf::MutProxy;
-
-    let mut m1 = TestAllTypes::new();
-    m1.set_optional_int32(1);
-    let mut m2 = TestAllTypes::new();
-    m2.as_mut().set(m1.as_view());
-
-    assert_that!(m2.optional_int32(), eq(1i32));
-}
-
 #[test]
 fn test_group() {
     let mut m = TestAllTypes::new();
@@ -799,3 +778,39 @@ fn test_submsg_setter() {
 
     assert_that!(parent.optional_nested_message().bb(), eq(7));
 }
+
+#[test]
+fn test_clone() {
+    let mut m = TestAllTypes::new();
+    m.set_optional_int32(42);
+    let clone = m.clone();
+    assert_that!(clone.optional_int32(), eq(42));
+    m.clear_optional_int32();
+    assert_that!(m.has_optional_int32(), eq(false));
+    assert_that!(clone.has_optional_int32(), eq(true));
+    assert_that!(clone.optional_int32(), eq(42));
+}
+
+#[test]
+fn test_to_owned() {
+    let mut m = TestAllTypes::new();
+    m.set_optional_int32(42);
+    let clone = m.as_view().to_owned();
+    assert_that!(clone.optional_int32(), eq(42));
+
+    // to_owned should create a new message (modifying the original shouldn't affect
+    // the to_owned).
+    m.clear_optional_int32();
+    assert_that!(m.has_optional_int32(), eq(false));
+    assert_that!(clone.has_optional_int32(), eq(true));
+    assert_that!(clone.optional_int32(), eq(42));
+
+    let mut submsg_mut = m.optional_nested_message_mut();
+    submsg_mut.set_bb(7);
+    let submsg_clone = submsg_mut.to_owned();
+    assert_that!(submsg_clone.bb(), eq(7));
+    assert_that!(submsg_mut.bb(), eq(7));
+    submsg_mut.set_bb(8);
+    assert_that!(submsg_clone.bb(), eq(7));
+    assert_that!(submsg_mut.bb(), eq(8));
+}
diff --git a/rust/test/shared/reserved_test.rs b/rust/test/shared/bad_names_test.rs
similarity index 68%
rename from rust/test/shared/reserved_test.rs
rename to rust/test/shared/bad_names_test.rs
index 0d2cb52bb6..a4b133b92f 100644
--- a/rust/test/shared/reserved_test.rs
+++ b/rust/test/shared/bad_names_test.rs
@@ -5,10 +5,8 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-/// Test covering proto compilation with reserved words.
+use bad_names_proto::*;
 use googletest::prelude::*;
-use reserved_proto::Self__mangled_because_ident_isnt_a_legal_raw_identifier;
-use reserved_proto::{r#enum, Ref};
 
 #[test]
 fn test_reserved_keyword_in_accessors() {
@@ -22,3 +20,13 @@ fn test_reserved_keyword_in_messages() {
     let _ = r#enum::new();
     let _ = Ref::new().r#const();
 }
+
+#[test]
+fn test_collision_in_accessors() {
+    let mut m = AccessorsCollide::new();
+    m.set_x_mut_5(false);
+    assert_that!(m.x_mut_5(), eq(false));
+    assert_that!(m.has_x_mut_5(), eq(true));
+    assert_that!(m.has_x(), eq(false));
+    assert_that!(m.has_set_x_2(), eq(false));
+}
diff --git a/rust/test/shared/enum_test.rs b/rust/test/shared/enum_test.rs
index c11a4906c0..1c8e7fda84 100644
--- a/rust/test/shared/enum_test.rs
+++ b/rust/test/shared/enum_test.rs
@@ -9,6 +9,7 @@
 
 use enums_proto::*;
 use googletest::prelude::*;
+use protobuf::Enum;
 use unittest_proto::*;
 
 #[test]
@@ -60,12 +61,12 @@ fn test_closed_enum_is_nonexhaustive() {
 #[test]
 fn test_closed_enum_conversion() {
     assert_that!(i32::from(TestSparseEnum::SparseA), eq(123));
-    assert_that!(TestSparseEnum::try_from(123), ok(eq(TestSparseEnum::SparseA)));
+    assert_that!(TestSparseEnum::try_from(123), ok(eq(&TestSparseEnum::SparseA)));
 
     assert_that!(i32::from(TestSparseEnum::SparseD), eq(-15));
-    assert_that!(TestSparseEnum::try_from(-15), ok(eq(TestSparseEnum::SparseD)));
+    assert_that!(TestSparseEnum::try_from(-15), ok(eq(&TestSparseEnum::SparseD)));
 
-    assert_that!(TestSparseEnum::try_from(0), ok(eq(TestSparseEnum::SparseF)));
+    assert_that!(TestSparseEnum::try_from(0), ok(eq(&TestSparseEnum::SparseF)));
     assert_that!(TestSparseEnum::try_from(1), err(anything()));
 }
 
@@ -77,9 +78,9 @@ fn test_closed_aliased_enum_conversion() {
     assert_that!(i32::from(TestEnumWithDupValue::Bar2), eq(2));
     assert_that!(i32::from(TestEnumWithDupValue::Baz), eq(3));
 
-    assert_that!(TestEnumWithDupValue::try_from(1), ok(eq(TestEnumWithDupValue::Foo1)));
-    assert_that!(TestEnumWithDupValue::try_from(2), ok(eq(TestEnumWithDupValue::Bar1)));
-    assert_that!(TestEnumWithDupValue::try_from(3), ok(eq(TestEnumWithDupValue::Baz)));
+    assert_that!(TestEnumWithDupValue::try_from(1), ok(eq(&TestEnumWithDupValue::Foo1)));
+    assert_that!(TestEnumWithDupValue::try_from(2), ok(eq(&TestEnumWithDupValue::Bar1)));
+    assert_that!(TestEnumWithDupValue::try_from(3), ok(eq(&TestEnumWithDupValue::Baz)));
     assert_that!(TestEnumWithDupValue::try_from(0), err(anything()));
     assert_that!(TestEnumWithDupValue::try_from(4), err(anything()));
 
@@ -167,3 +168,24 @@ fn test_enum_conversion_failure_impls_std_error() {
     let err = TestSparseEnum::try_from(1).unwrap_err();
     let _test_compiles: &dyn std::error::Error = &err;
 }
+
+#[test]
+fn test_is_known_for_closed_enum() {
+    assert_that!(test_all_types::NestedEnum::is_known(-2), eq(false));
+    assert_that!(test_all_types::NestedEnum::is_known(-1), eq(true));
+    assert_that!(test_all_types::NestedEnum::is_known(0), eq(false));
+    assert_that!(test_all_types::NestedEnum::is_known(1), eq(true));
+    assert_that!(test_all_types::NestedEnum::is_known(2), eq(true));
+    assert_that!(test_all_types::NestedEnum::is_known(3), eq(true));
+    assert_that!(test_all_types::NestedEnum::is_known(4), eq(false));
+}
+
+#[test]
+fn test_is_known_for_open_enum() {
+    assert_that!(TestEnumWithNumericNames::is_known(-1), eq(false));
+    assert_that!(TestEnumWithNumericNames::is_known(0), eq(true));
+    assert_that!(TestEnumWithNumericNames::is_known(1), eq(true));
+    assert_that!(TestEnumWithNumericNames::is_known(2), eq(true));
+    assert_that!(TestEnumWithNumericNames::is_known(3), eq(true));
+    assert_that!(TestEnumWithNumericNames::is_known(4), eq(false));
+}
diff --git a/rust/test/shared/matchers.rs b/rust/test/shared/matchers.rs
deleted file mode 100644
index 70bea18464..0000000000
--- a/rust/test/shared/matchers.rs
+++ /dev/null
@@ -1,59 +0,0 @@
-use googletest::description::Description;
-use googletest::matcher::MatcherResult;
-use googletest::prelude::*;
-use protobuf::{AbsentField, Optional, PresentField, ProxiedWithPresence};
-use std::marker::PhantomData;
-
-/// ===============================
-///               IS_UNSET
-/// ===============================
-pub fn is_unset<'a, T: std::fmt::Debug + ProxiedWithPresence + ?Sized + 'a>()
--> impl Matcher<ActualT = Optional<PresentField<'a, T>, AbsentField<'a, T>>> {
-    UnsetMatcher::<T> { _phantom: PhantomData }
-}
-
-struct UnsetMatcher<'a, T: ProxiedWithPresence + ?Sized> {
-    _phantom: PhantomData<PresentField<'a, T>>,
-}
-
-impl<'a, T: std::fmt::Debug + ProxiedWithPresence + ?Sized> Matcher for UnsetMatcher<'a, T> {
-    type ActualT = Optional<PresentField<'a, T>, AbsentField<'a, T>>;
-
-    fn matches(&self, actual: &Self::ActualT) -> MatcherResult {
-        actual.is_unset().into()
-    }
-
-    fn describe(&self, matcher_result: MatcherResult) -> Description {
-        match matcher_result {
-            MatcherResult::Match => "is not set".into(),
-            MatcherResult::NoMatch => "is set".into(),
-        }
-    }
-}
-
-/// ===============================
-///               IS_SET
-/// ===============================
-pub fn is_set<'a, T: std::fmt::Debug + ProxiedWithPresence + ?Sized + 'a>()
--> impl Matcher<ActualT = Optional<PresentField<'a, T>, AbsentField<'a, T>>> {
-    SetMatcher::<T> { _phantom: PhantomData }
-}
-
-struct SetMatcher<'a, T: ProxiedWithPresence + ?Sized> {
-    _phantom: PhantomData<PresentField<'a, T>>,
-}
-
-impl<'a, T: std::fmt::Debug + ProxiedWithPresence + ?Sized> Matcher for SetMatcher<'a, T> {
-    type ActualT = Optional<PresentField<'a, T>, AbsentField<'a, T>>;
-
-    fn matches(&self, actual: &Self::ActualT) -> MatcherResult {
-        actual.is_set().into()
-    }
-
-    fn describe(&self, matcher_result: MatcherResult) -> Description {
-        match matcher_result {
-            MatcherResult::Match => "is set".into(),
-            MatcherResult::NoMatch => "is not set".into(),
-        }
-    }
-}
diff --git a/rust/test/shared/utf8/BUILD b/rust/test/shared/utf8/BUILD
index a0ffd15f51..7ff155158e 100644
--- a/rust/test/shared/utf8/BUILD
+++ b/rust/test/shared/utf8/BUILD
@@ -9,14 +9,12 @@ rust_test(
     srcs = ["utf8_test.rs"],
     aliases = {
         "//rust:protobuf_cpp": "protobuf",
-        "//rust/test/shared:matchers_cpp": "matchers",
     },
     deps = [
         ":feature_verify_cc_rust_proto",
         ":no_features_proto2_cc_rust_proto",
         ":no_features_proto3_cc_rust_proto",
         "//rust:protobuf_cpp",
-        "//rust/test/shared:matchers_cpp",
         "@crate_index//:googletest",
     ],
 )
@@ -26,14 +24,12 @@ rust_test(
     srcs = ["utf8_test.rs"],
     aliases = {
         "//rust:protobuf_upb": "protobuf",
-        "//rust/test/shared:matchers_upb": "matchers",
     },
     deps = [
         ":feature_verify_upb_rust_proto",
         ":no_features_proto2_upb_rust_proto",
         ":no_features_proto3_upb_rust_proto",
         "//rust:protobuf_upb",
-        "//rust/test/shared:matchers_upb",
         "@crate_index//:googletest",
     ],
 )
diff --git a/rust/upb.rs b/rust/upb.rs
index 5a0c07e471..554af66bc3 100644
--- a/rust/upb.rs
+++ b/rust/upb.rs
@@ -10,13 +10,11 @@
 use crate::__internal::{Enum, Private};
 use crate::{
     Map, MapIter, MapMut, MapView, Mut, ProtoStr, Proxied, ProxiedInMapValue, ProxiedInRepeated,
-    Repeated, RepeatedMut, RepeatedView, SettableValue, View, ViewProxy,
+    Repeated, RepeatedMut, RepeatedView, View, ViewProxy,
 };
 use core::fmt::Debug;
 use std::alloc::Layout;
-use std::fmt;
 use std::mem::{size_of, ManuallyDrop, MaybeUninit};
-use std::ops::Deref;
 use std::ptr::{self, NonNull};
 use std::slice;
 use std::sync::OnceLock;
@@ -60,83 +58,7 @@ impl ScratchSpace {
     }
 }
 
-/// Serialized Protobuf wire format data.
-///
-/// It's typically produced by `<Message>::serialize()`.
-pub struct SerializedData {
-    data: NonNull<u8>,
-    len: usize,
-
-    // The arena that owns `data`.
-    _arena: Arena,
-}
-
-impl SerializedData {
-    /// Construct `SerializedData` from raw pointers and its owning arena.
-    ///
-    /// # Safety
-    /// - `arena` must be have allocated `data`
-    /// - `data` must be readable for `len` bytes and not mutate while this
-    ///   struct exists
-    pub unsafe fn from_raw_parts(arena: Arena, data: NonNull<u8>, len: usize) -> Self {
-        SerializedData { _arena: arena, data, len }
-    }
-
-    /// Gets a raw slice pointer.
-    pub fn as_ptr(&self) -> *const [u8] {
-        ptr::slice_from_raw_parts(self.data.as_ptr(), self.len)
-    }
-}
-
-impl Deref for SerializedData {
-    type Target = [u8];
-    fn deref(&self) -> &Self::Target {
-        // SAFETY: `data` is valid for `len` bytes as promised by
-        //         the caller of `SerializedData::from_raw_parts`.
-        unsafe { slice::from_raw_parts(self.data.as_ptr(), self.len) }
-    }
-}
-
-impl fmt::Debug for SerializedData {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        fmt::Debug::fmt(self.deref(), f)
-    }
-}
-
-impl SettableValue<[u8]> for SerializedData {
-    fn set_on<'msg>(self, _private: Private, mut mutator: Mut<'msg, [u8]>)
-    where
-        [u8]: 'msg,
-    {
-        mutator.set(self.as_ref())
-    }
-}
-
-// TODO: Investigate replacing this with direct access to UPB bits.
-pub type MessagePresentMutData<'msg, T> = crate::vtable::RawVTableOptionalMutatorData<'msg, T>;
-pub type MessageAbsentMutData<'msg, T> = crate::vtable::RawVTableOptionalMutatorData<'msg, T>;
-pub type BytesPresentMutData<'msg> = crate::vtable::RawVTableOptionalMutatorData<'msg, [u8]>;
-pub type BytesAbsentMutData<'msg> = crate::vtable::RawVTableOptionalMutatorData<'msg, [u8]>;
-pub type InnerBytesMut<'msg> = crate::vtable::RawVTableMutator<'msg, [u8]>;
-pub type InnerPrimitiveMut<'msg, T> = crate::vtable::RawVTableMutator<'msg, T>;
-
-#[derive(Debug)]
-pub struct MessageVTable {
-    pub getter: unsafe extern "C" fn(msg: RawMessage) -> Option<RawMessage>,
-    pub mut_getter: unsafe extern "C" fn(msg: RawMessage, arena: RawArena) -> RawMessage,
-    pub clearer: unsafe extern "C" fn(msg: RawMessage),
-}
-
-impl MessageVTable {
-    pub const fn new(
-        _private: Private,
-        getter: unsafe extern "C" fn(msg: RawMessage) -> Option<RawMessage>,
-        mut_getter: unsafe extern "C" fn(msg: RawMessage, arena: RawArena) -> RawMessage,
-        clearer: unsafe extern "C" fn(msg: RawMessage),
-    ) -> Self {
-        MessageVTable { getter, mut_getter, clearer }
-    }
-}
+pub type SerializedData = upb::OwnedArenaBox<[u8]>;
 
 /// The raw contents of every generated message.
 #[derive(Debug)]
@@ -233,6 +155,14 @@ impl InnerRepeated {
     pub fn as_mut(&mut self) -> InnerRepeatedMut<'_> {
         InnerRepeatedMut::new(Private, self.raw, &self.arena)
     }
+
+    pub fn raw(&self) -> RawRepeatedField {
+        self.raw
+    }
+
+    pub fn arena(&self) -> &Arena {
+        &self.arena
+    }
 }
 
 /// The raw type-erased pointer version of `RepeatedMut`.
@@ -252,6 +182,7 @@ impl<'msg> InnerRepeatedMut<'msg> {
 macro_rules! impl_repeated_base {
     ($t:ty, $elem_t:ty, $ufield:ident, $upb_tag:expr) => {
         #[allow(dead_code)]
+        #[inline]
         fn repeated_new(_: Private) -> Repeated<$t> {
             let arena = Arena::new();
             Repeated::from_inner(InnerRepeated {
@@ -263,9 +194,11 @@ macro_rules! impl_repeated_base {
         unsafe fn repeated_free(_: Private, _f: &mut Repeated<$t>) {
             // No-op: the memory will be dropped by the arena.
         }
+        #[inline]
         fn repeated_len(f: View<Repeated<$t>>) -> usize {
             unsafe { upb_Array_Size(f.as_raw(Private)) }
         }
+        #[inline]
         fn repeated_push(mut f: Mut<Repeated<$t>>, v: View<$t>) {
             let arena = f.raw_arena(Private);
             unsafe {
@@ -276,16 +209,19 @@ macro_rules! impl_repeated_base {
                 ));
             }
         }
+        #[inline]
         fn repeated_clear(mut f: Mut<Repeated<$t>>) {
             unsafe {
                 upb_Array_Resize(f.as_raw(Private), 0, f.raw_arena(Private));
             }
         }
+        #[inline]
         unsafe fn repeated_get_unchecked(f: View<Repeated<$t>>, i: usize) -> View<$t> {
             unsafe {
                 <$t as UpbTypeConversions>::from_message_value(upb_Array_Get(f.as_raw(Private), i))
             }
         }
+        #[inline]
         unsafe fn repeated_set_unchecked(mut f: Mut<Repeated<$t>>, i: usize, v: View<$t>) {
             let arena = f.raw_arena(Private);
             unsafe {
@@ -296,6 +232,17 @@ macro_rules! impl_repeated_base {
                 )
             }
         }
+        #[inline]
+        fn repeated_reserve(mut f: Mut<Repeated<$t>>, additional: usize) {
+            // SAFETY:
+            // - `upb_Array_Reserve` is unsafe but assumed to be sound when called on a
+            //   valid array.
+            unsafe {
+                let arena = f.raw_arena(Private);
+                let size = upb_Array_Size(f.as_raw(Private));
+                assert!(upb_Array_Reserve(f.as_raw(Private), size + additional, arena));
+            }
+        }
     };
 }
 
@@ -332,6 +279,7 @@ macro_rules! impl_repeated_bytes {
             unsafe impl ProxiedInRepeated for $t {
                 impl_repeated_base!($t, PtrAndLen, str_val, $upb_tag);
 
+                #[inline]
                 fn repeated_copy_from(src: View<Repeated<$t>>, mut dest: Mut<Repeated<$t>>) {
                     let len = src.len();
                     // SAFETY:
@@ -443,6 +391,17 @@ pub fn cast_enum_repeated_mut<E: Enum + ProxiedInRepeated>(
     }
 }
 
+/// Cast a `RepeatedMut<SomeEnum>` to `RepeatedMut<i32>` and call
+/// repeated_reserve.
+pub fn reserve_enum_repeated_mut<E: Enum + ProxiedInRepeated>(
+    private: Private,
+    repeated: RepeatedMut<E>,
+    additional: usize,
+) {
+    let int_repeated = cast_enum_repeated_mut(private, repeated);
+    ProxiedInRepeated::repeated_reserve(int_repeated, additional);
+}
+
 /// Returns a static empty RepeatedView.
 pub fn empty_array<T: ?Sized + ProxiedInRepeated>() -> RepeatedView<'static, T> {
     // TODO: Consider creating a static empty array in C.
@@ -814,22 +773,6 @@ mod tests {
     use super::*;
     use googletest::prelude::*;
 
-    #[test]
-    fn test_serialized_data_roundtrip() {
-        let arena = Arena::new();
-        let original_data = b"Hello world";
-        let len = original_data.len();
-
-        let serialized_data = unsafe {
-            SerializedData::from_raw_parts(
-                arena,
-                NonNull::new(original_data as *const _ as *mut _).unwrap(),
-                len,
-            )
-        };
-        assert_that!(&*serialized_data, eq(b"Hello world"));
-    }
-
     #[test]
     fn assert_c_type_sizes() {
         // TODO: add these same asserts in C++.
diff --git a/rust/upb/BUILD b/rust/upb/BUILD
index 894d4950e0..563794994b 100644
--- a/rust/upb/BUILD
+++ b/rust/upb/BUILD
@@ -23,6 +23,7 @@ rust_library(
         "message_value.rs",
         "mini_table.rs",
         "opaque_pointee.rs",
+        "owned_arena_box.rs",
         "string_view.rs",
         "wire.rs",
     ],
@@ -45,5 +46,6 @@ cc_library(
         "//upb:mem",
         "//upb:message",
         "//upb:message_copy",
+        "//upb/mini_table",
     ],
 )
diff --git a/rust/upb/arena.rs b/rust/upb/arena.rs
index 51e8958e4e..76bb9e1ca0 100644
--- a/rust/upb/arena.rs
+++ b/rust/upb/arena.rs
@@ -3,7 +3,7 @@ use std::alloc::{self, Layout};
 use std::cell::UnsafeCell;
 use std::marker::PhantomData;
 use std::mem::{align_of, MaybeUninit};
-use std::ptr::NonNull;
+use std::ptr::{self, NonNull};
 use std::slice;
 
 opaque_pointee!(upb_Arena);
@@ -22,11 +22,11 @@ const _CHECK_UPB_MALLOC_ALIGN_AT_LEAST_POINTER_ALIGNED: () =
 /// This is an owning type and will automatically free the arena when
 /// dropped.
 ///
-/// Note that this type is neither `Sync` nor `Send`. The upb_Arena C object
-/// could be understood as being Sync (at least vacuously, as there are no
-/// const-ptr functions on upb_Arena's API), but the Rust Arena is
-/// necessarily expressed as interior mutability (&self rather than &mut self
-/// receivers) See https://doc.rust-lang.org/nomicon/lifetime-mismatch.html and
+/// Note that this type is not `Sync` as it implements unsynchronized interior
+/// mutability. The upb_Arena C object could be understood as being Sync (at
+/// least vacuously under current API since there are not any const upb_Arena*
+/// API functions), but the Rust Arena is necessarily expressed as interior
+/// mutability (&self rather than &mut self receivers) See https://doc.rust-lang.org/nomicon/lifetime-mismatch.html and
 /// https://blog.reverberate.org/2021/12/19/arenas-and-rust.html, and the
 /// 'known problems' section of https://rust-lang.github.io/rust-clippy/master/index.html#/mut_from_ref.
 #[derive(Debug)]
@@ -36,6 +36,10 @@ pub struct Arena {
     _not_sync: PhantomData<UnsafeCell<()>>,
 }
 
+// SAFETY: `Arena` uniquely holds the underlying RawArena and has no
+// thread-local data.
+unsafe impl Send for Arena {}
+
 impl Arena {
     /// Allocates a fresh arena.
     #[inline]
@@ -91,6 +95,72 @@ impl Arena {
         //   `UPB_MALLOC_ALIGN` boundary.
         unsafe { slice::from_raw_parts_mut(ptr.cast(), layout.size()) }
     }
+
+    /// Same as alloc() but panics if `layout.align() > UPB_MALLOC_ALIGN`.
+    #[allow(clippy::mut_from_ref)]
+    #[inline]
+    pub fn checked_alloc(&self, layout: Layout) -> &mut [MaybeUninit<u8>] {
+        assert!(layout.align() <= UPB_MALLOC_ALIGN);
+        // SAFETY: layout.align() <= UPB_MALLOC_ALIGN asserted.
+        unsafe { self.alloc(layout) }
+    }
+
+    /// Copies the T into this arena and returns a pointer to the T data inside
+    /// the arena.
+    pub fn copy_in<'a, T: Copy>(&'a self, data: &T) -> &'a T {
+        let layout = Layout::for_value(data);
+        let alloc = self.checked_alloc(layout);
+
+        // SAFETY:
+        // - alloc is valid for `layout.len()` bytes and is the uninit bytes are written
+        //   to not read from until written.
+        // - T is copy so copying the bytes of the value is sound.
+        unsafe {
+            let alloc = alloc.as_mut_ptr().cast::<MaybeUninit<T>>();
+            // let data = (data as *const T).cast::<MaybeUninit<T>>();
+            (*alloc).write(*data)
+        }
+    }
+
+    pub fn copy_str_in<'a>(&'a self, s: &str) -> &'a str {
+        let copied_bytes = self.copy_slice_in(s.as_bytes());
+        // SAFETY: `copied_bytes` has same contents as `s` and so must meet &str
+        // criteria.
+        unsafe { std::str::from_utf8_unchecked(copied_bytes) }
+    }
+
+    pub fn copy_slice_in<'a, T: Copy>(&'a self, data: &[T]) -> &'a [T] {
+        let layout = Layout::for_value(data);
+        let alloc: *mut T = self.checked_alloc(layout).as_mut_ptr().cast();
+
+        // SAFETY:
+        // - uninit_alloc is valid for `layout.len()` bytes and is the uninit bytes are
+        //   written to not read from until written.
+        // - T is copy so copying the bytes of the values is sound.
+        unsafe {
+            ptr::copy_nonoverlapping(data.as_ptr(), alloc, data.len());
+            slice::from_raw_parts_mut(alloc, data.len())
+        }
+    }
+
+    /// Fuse two arenas so they share the same lifetime.
+    ///
+    /// `fuse` will make it so that the memory allocated by `self` or `other` is
+    /// guaranteed to last until both `self` and `other` have been dropped.
+    /// The pointers returned by `Arena::alloc` will continue to be valid so
+    /// long as either `self` or `other` has not been dropped.
+    ///
+    pub fn fuse(&self, other: &Arena) {
+        // SAFETY: `self.raw()` and `other.raw()` are both valid UPB arenas.
+        let success = unsafe { upb_Arena_Fuse(self.raw(), other.raw()) };
+        if !success {
+            // Fusing can fail if any of the arenas has an initial block i.e. the arena is
+            // backed by a preallocated chunk of memory that it doesn't own and thus cannot
+            // lifetime extend. This function panics because this is typically not a
+            // recoverable error but a logic bug in a program.
+            panic!("Could not fuse two UPB arenas.");
+        }
+    }
 }
 
 impl Default for Arena {
@@ -113,6 +183,7 @@ extern "C" {
     fn upb_Arena_New() -> Option<RawArena>;
     fn upb_Arena_Free(arena: RawArena);
     fn upb_Arena_Malloc(arena: RawArena, size: usize) -> *mut u8;
+    fn upb_Arena_Fuse(arena1: RawArena, arena2: RawArena) -> bool;
 }
 
 #[cfg(test)]
diff --git a/rust/upb/array.rs b/rust/upb/array.rs
index 8c0abf8c81..a8b2fb1ef7 100644
--- a/rust/upb/array.rs
+++ b/rust/upb/array.rs
@@ -12,6 +12,7 @@ extern "C" {
     pub fn upb_Array_Get(arr: RawArray, i: usize) -> upb_MessageValue;
     pub fn upb_Array_Append(arr: RawArray, val: upb_MessageValue, arena: RawArena) -> bool;
     pub fn upb_Array_Resize(arr: RawArray, size: usize, arena: RawArena) -> bool;
+    pub fn upb_Array_Reserve(arr: RawArray, size: usize, arena: RawArena) -> bool;
     pub fn upb_Array_MutableDataPtr(arr: RawArray) -> *mut std::ffi::c_void;
     pub fn upb_Array_DataPtr(arr: RawArray) -> *const std::ffi::c_void;
     pub fn upb_Array_GetMutable(arr: RawArray, i: usize) -> upb_MutableMessageValue;
diff --git a/rust/upb/lib.rs b/rust/upb/lib.rs
index f557d1b024..643018afe0 100644
--- a/rust/upb/lib.rs
+++ b/rust/upb/lib.rs
@@ -4,8 +4,8 @@ pub use arena::{upb_Arena, Arena, RawArena};
 mod array;
 pub use array::{
     upb_Array, upb_Array_Append, upb_Array_DataPtr, upb_Array_Get, upb_Array_GetMutable,
-    upb_Array_MutableDataPtr, upb_Array_New, upb_Array_Resize, upb_Array_Set, upb_Array_Size,
-    RawArray,
+    upb_Array_MutableDataPtr, upb_Array_New, upb_Array_Reserve, upb_Array_Resize, upb_Array_Set,
+    upb_Array_Size, RawArray,
 };
 
 mod ctype;
@@ -21,18 +21,27 @@ pub use map::{
 };
 
 mod message;
-pub use message::{upb_Message, upb_Message_DeepClone, upb_Message_DeepCopy, RawMessage};
+pub use message::{
+    upb_Message, upb_Message_DeepClone, upb_Message_DeepCopy, upb_Message_New,
+    upb_Message_SetBaseField, RawMessage,
+};
 
 mod message_value;
 pub use message_value::{upb_MessageValue, upb_MutableMessageValue};
 
 mod mini_table;
-pub use mini_table::{upb_MiniTable, RawMiniTable};
+pub use mini_table::{
+    upb_MiniTable, upb_MiniTableField, upb_MiniTable_FindFieldByNumber, RawMiniTable,
+    RawMiniTableField,
+};
 
 mod opaque_pointee;
 
+mod owned_arena_box;
+pub use owned_arena_box::OwnedArenaBox;
+
 mod string_view;
 pub use string_view::StringView;
 
-mod wire;
-pub use wire::{upb_Decode, upb_Encode, DecodeStatus, EncodeStatus};
+pub mod wire;
+pub use wire::{upb_Decode, DecodeStatus, EncodeStatus};
diff --git a/rust/upb/message.rs b/rust/upb/message.rs
index 2a9fe91e30..a4159a1fb6 100644
--- a/rust/upb/message.rs
+++ b/rust/upb/message.rs
@@ -1,11 +1,15 @@
 use crate::opaque_pointee::opaque_pointee;
-use crate::{upb_MiniTable, RawArena};
+use crate::{upb_MiniTable, upb_MiniTableField, RawArena};
 use std::ptr::NonNull;
 
 opaque_pointee!(upb_Message);
 pub type RawMessage = NonNull<upb_Message>;
 
 extern "C" {
+    /// SAFETY: No constraints.
+    pub fn upb_Message_New(mini_table: *const upb_MiniTable, arena: RawArena)
+    -> Option<RawMessage>;
+
     pub fn upb_Message_DeepCopy(
         dst: RawMessage,
         src: RawMessage,
@@ -18,4 +22,10 @@ extern "C" {
         mini_table: *const upb_MiniTable,
         arena: RawArena,
     ) -> Option<RawMessage>;
+
+    pub fn upb_Message_SetBaseField(
+        m: RawMessage,
+        mini_table: *const upb_MiniTableField,
+        val: *const std::ffi::c_void,
+    );
 }
diff --git a/rust/upb/mini_table.rs b/rust/upb/mini_table.rs
index dc704caf0e..9aeca3e63a 100644
--- a/rust/upb/mini_table.rs
+++ b/rust/upb/mini_table.rs
@@ -3,3 +3,13 @@ use std::ptr::NonNull;
 
 opaque_pointee!(upb_MiniTable);
 pub type RawMiniTable = NonNull<upb_MiniTable>;
+
+opaque_pointee!(upb_MiniTableField);
+pub type RawMiniTableField = NonNull<upb_MiniTableField>;
+
+extern "C" {
+    pub fn upb_MiniTable_FindFieldByNumber(
+        m: *const upb_MiniTable,
+        number: u32,
+    ) -> *const upb_MiniTableField;
+}
diff --git a/rust/upb/owned_arena_box.rs b/rust/upb/owned_arena_box.rs
new file mode 100644
index 0000000000..9f10accc49
--- /dev/null
+++ b/rust/upb/owned_arena_box.rs
@@ -0,0 +1,111 @@
+use crate::Arena;
+use std::fmt::{self, Debug};
+use std::ops::{Deref, DerefMut};
+use std::ptr::NonNull;
+
+/// An 'owned' T, similar to a Box<T> where the T is data
+/// held in a upb Arena. By holding the data pointer and a corresponding arena
+/// together the data liveness is be maintained.
+///
+/// This struct is conceptually self-referential, where `data` points at memory
+/// inside `arena`. This avoids typical concerns of self-referential data
+/// structures because `arena` modifications (other than drop) will never
+/// invalidate `data`, and `data` and `arena` are both behind indirections which
+/// avoids any concern with std::mem::swap.
+pub struct OwnedArenaBox<T: ?Sized + 'static> {
+    data: NonNull<T>,
+    arena: Arena,
+}
+
+impl<T: ?Sized + 'static> OwnedArenaBox<T> {
+    /// Construct `OwnedArenaBox` from raw pointers and its owning arena.
+    ///
+    /// # Safety
+    /// - `data` must satisfy the safety constraints of pointer::as_mut::<'a>()
+    ///   where 'a is the passed arena's lifetime (`data` should be valid and
+    ///   not mutated while this struct is live).
+    /// - `data` should be a pointer into a block from a previous allocation on
+    ///   `arena`, or to another arena fused to it, or should be pointing at
+    ///   'static data (and if it is pointing at any struct like upb_Message,
+    ///   all data transitively reachable should similarly be kept live by
+    ///   `arena` or be 'static).
+    pub unsafe fn new(data: NonNull<T>, arena: Arena) -> Self {
+        OwnedArenaBox { arena, data }
+    }
+
+    pub fn data(&self) -> *const T {
+        self.data.as_ptr()
+    }
+
+    pub fn into_parts(self) -> (NonNull<T>, Arena) {
+        (self.data, self.arena)
+    }
+}
+
+impl<T: ?Sized + 'static> Deref for OwnedArenaBox<T> {
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        self.as_ref()
+    }
+}
+
+impl<T: ?Sized + 'static> DerefMut for OwnedArenaBox<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        self.as_mut()
+    }
+}
+
+impl<T: ?Sized + 'static> AsRef<T> for OwnedArenaBox<T> {
+    fn as_ref(&self) -> &T {
+        // SAFETY:
+        // - `data` is valid under the conditions set on ::new().
+        unsafe { self.data.as_ref() }
+    }
+}
+
+impl<T: ?Sized + 'static> AsMut<T> for OwnedArenaBox<T> {
+    fn as_mut(&mut self) -> &mut T {
+        // SAFETY:
+        // - `data` is valid under the conditions set on ::new().
+        unsafe { self.data.as_mut() }
+    }
+}
+
+impl<T: Debug + 'static> Debug for OwnedArenaBox<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_tuple("OwnedArenaBox").field(self.deref()).finish()
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::str;
+
+    #[test]
+    fn test_byte_slice_pointer_roundtrip() {
+        let arena = Arena::new();
+        let original_data: &'static [u8] = b"Hello world";
+        let owned_data = unsafe { OwnedArenaBox::new(original_data.into(), arena) };
+        assert_eq!(&*owned_data, b"Hello world");
+    }
+
+    #[test]
+    fn test_alloc_str_roundtrip() {
+        let arena = Arena::new();
+        let s: &str = "Hello";
+        let arena_alloc_str: NonNull<str> = arena.copy_str_in(s).into();
+        let owned_data = unsafe { OwnedArenaBox::new(arena_alloc_str, arena) };
+        assert_eq!(&*owned_data, s);
+    }
+
+    #[test]
+    fn test_sized_type_roundtrip() {
+        let arena = Arena::new();
+        let arena_alloc_u32: NonNull<u32> = arena.copy_in(&7u32).into();
+        let mut owned_data = unsafe { OwnedArenaBox::new(arena_alloc_u32, arena) };
+        assert_eq!(*owned_data, 7);
+        *owned_data = 8;
+        assert_eq!(*owned_data, 8);
+    }
+}
diff --git a/rust/upb/upb_api.c b/rust/upb/upb_api.c
index 6208be2464..e6d508db1d 100644
--- a/rust/upb/upb_api.c
+++ b/rust/upb/upb_api.c
@@ -10,9 +10,11 @@
 
 #define UPB_BUILD_API
 
-#include "upb/mem/arena.h"      // IWYU pragma: keep
-#include "upb/message/array.h"  // IWYU pragma: keep
-#include "upb/message/copy.h"   // IWYU pragma: keep
-#include "upb/message/map.h"    // IWYU pragma: keep
+#include "upb/mem/arena.h"          // IWYU pragma: keep
+#include "upb/message/array.h"      // IWYU pragma: keep
+#include "upb/message/copy.h"       // IWYU pragma: keep
+#include "upb/message/map.h"        // IWYU pragma: keep
+#include "upb/message/accessors.h"  // IWYU pragma: keep
+#include "upb/mini_table/message.h" // IWYU pragma: keep
 
 const size_t __rust_proto_kUpb_Map_Begin = kUpb_Map_Begin;
diff --git a/rust/upb/wire.rs b/rust/upb/wire.rs
index 2b68145cc2..aa335cc020 100644
--- a/rust/upb/wire.rs
+++ b/rust/upb/wire.rs
@@ -1,8 +1,9 @@
-use crate::{upb_ExtensionRegistry, upb_MiniTable, RawArena, RawMessage};
+use crate::{upb_ExtensionRegistry, upb_MiniTable, Arena, OwnedArenaBox, RawArena, RawMessage};
+use std::ptr::NonNull;
 
 // LINT.IfChange(encode_status)
 #[repr(C)]
-#[derive(PartialEq, Eq, Copy, Clone)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
 pub enum EncodeStatus {
     Ok = 0,
     OutOfMemory = 1,
@@ -13,7 +14,7 @@ pub enum EncodeStatus {
 
 // LINT.IfChange(decode_status)
 #[repr(C)]
-#[derive(PartialEq, Eq, Copy, Clone)]
+#[derive(PartialEq, Eq, Copy, Clone, Debug)]
 pub enum DecodeStatus {
     Ok = 0,
     Malformed = 1,
@@ -25,7 +26,62 @@ pub enum DecodeStatus {
 }
 // LINT.ThenChange()
 
+/// If Err, then EncodeStatus != Ok.
+///
+/// SAFETY:
+/// - `msg` must be associated with `mini_table`.
+pub unsafe fn encode(
+    msg: RawMessage,
+    mini_table: *const upb_MiniTable,
+) -> Result<OwnedArenaBox<[u8]>, EncodeStatus> {
+    let arena = Arena::new();
+    let mut buf: *mut u8 = std::ptr::null_mut();
+    let mut len = 0usize;
+
+    // SAFETY:
+    // - `mini_table` is the one associated with `msg`.
+    // - `buf` and `buf_size` are legally writable.
+    let status = upb_Encode(msg, mini_table, 0, arena.raw(), &mut buf, &mut len);
+
+    if status == EncodeStatus::Ok {
+        assert!(!buf.is_null()); // EncodeStatus Ok should never return NULL data, even for len=0.
+        // SAFETY: upb guarantees that `buf` is valid to read for `len`.
+        let slice = NonNull::new_unchecked(std::ptr::slice_from_raw_parts_mut(buf, len));
+        Ok(OwnedArenaBox::new(slice, arena))
+    } else {
+        Err(status)
+    }
+}
+
+/// Decodes into the provided message (merge semantics). If Err, then
+/// DecodeStatus != Ok.
+///
+/// SAFETY:
+/// - `msg` must be mutable.
+/// - `msg` must be associated with `mini_table`.
+pub unsafe fn decode(
+    buf: &[u8],
+    msg: RawMessage,
+    mini_table: *const upb_MiniTable,
+    arena: &Arena,
+) -> Result<(), DecodeStatus> {
+    let len = buf.len();
+    let buf = buf.as_ptr();
+    // SAFETY:
+    // - `mini_table` is the one associated with `msg`
+    // - `buf` is legally readable for at least `buf_size` bytes.
+    // - `extreg` is null.
+    let status = upb_Decode(buf, len, msg, mini_table, std::ptr::null(), 0, arena.raw());
+    match status {
+        DecodeStatus::Ok => Ok(()),
+        _ => Err(status),
+    }
+}
+
 extern "C" {
+    // SAFETY:
+    // - `mini_table` is the one associated with `msg`
+    // - `buf` and `buf_size` are legally writable.
     pub fn upb_Encode(
         msg: RawMessage,
         mini_table: *const upb_MiniTable,
@@ -35,6 +91,10 @@ extern "C" {
         buf_size: *mut usize,
     ) -> EncodeStatus;
 
+    // SAFETY:
+    // - `mini_table` is the one associated with `msg`
+    // - `buf` is legally readable for at least `buf_size` bytes.
+    // - `extreg` is either null or points at a valid upb_ExtensionRegistry.
     pub fn upb_Decode(
         buf: *const u8,
         buf_size: usize,
diff --git a/rust/vtable.rs b/rust/vtable.rs
deleted file mode 100644
index 52a0d87bc2..0000000000
--- a/rust/vtable.rs
+++ /dev/null
@@ -1,516 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2023 Google LLC.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-use crate::__internal::Private;
-use crate::__runtime::{
-    copy_bytes_in_arena_if_needed_by_runtime, InnerPrimitiveMut, MutatorMessageRef, PtrAndLen,
-    RawMessage,
-};
-use crate::{
-    AbsentField, FieldEntry, Mut, MutProxy, Optional, PresentField, PrimitiveMut, Proxied,
-    ProxiedWithPresence, View, ViewProxy,
-};
-use std::fmt::{self, Debug};
-use std::marker::PhantomData;
-use std::ptr::NonNull;
-
-/// A proxied type that can use a vtable to provide get/set access for a
-/// present field.
-///
-/// This vtable should consist of `unsafe fn`s that call thunks that operate on
-/// `RawMessage`. The structure of this vtable is different per proxied type.
-pub trait ProxiedWithRawVTable: Proxied {
-    /// The vtable for get/set access, stored in static memory.
-    type VTable: Debug + 'static;
-
-    fn make_view(_private: Private, mut_inner: RawVTableMutator<'_, Self>) -> View<'_, Self>;
-    fn make_mut(_private: Private, inner: RawVTableMutator<'_, Self>) -> Mut<'_, Self>;
-}
-
-/// A proxied type that can use a vtable to provide get/set/clear access for
-/// an optional field.
-///
-/// This vtable should consist of `unsafe fn`s that call thunks that operate on
-/// `RawMessage`. The structure of this vtable is different per-proxied type.
-pub trait ProxiedWithRawOptionalVTable: ProxiedWithRawVTable + ProxiedWithPresence {
-    /// The vtable for get/set/clear, must contain `Self::VTable`.
-    type OptionalVTable: Debug + 'static;
-
-    /// Cast from a static reference of `OptionalVTable` to `VTable`.
-    /// This should mean `OptionalVTable` contains a `VTable`.
-    fn upcast_vtable(
-        _private: Private,
-        optional_vtable: &'static Self::OptionalVTable,
-    ) -> &'static Self::VTable;
-}
-
-/// Constructs a new field entry from a raw message, a vtable for manipulation,
-/// and an eager check for whether the value is present or not.
-///
-/// # Safety
-/// - `msg_ref` must be valid to provide as an argument for `vtable`'s methods
-///   for `'msg`.
-/// - If given `msg_ref` as an argument, any values returned by `vtable` methods
-///   must be valid for `'msg`.
-/// - Operations on the vtable must be thread-compatible.
-#[doc(hidden)]
-pub unsafe fn new_vtable_field_entry<'msg, T: ProxiedWithRawOptionalVTable + ?Sized>(
-    _private: Private,
-    msg_ref: MutatorMessageRef<'msg>,
-    optional_vtable: &'static T::OptionalVTable,
-    is_set: bool,
-) -> FieldEntry<'msg, T>
-where
-    T: ProxiedWithPresence<
-            PresentMutData<'msg> = RawVTableOptionalMutatorData<'msg, T>,
-            AbsentMutData<'msg> = RawVTableOptionalMutatorData<'msg, T>,
-        >,
-{
-    // SAFETY: safe as promised by the caller of the function
-    let data = unsafe { RawVTableOptionalMutatorData::new(Private, msg_ref, optional_vtable) };
-    if is_set {
-        Optional::Set(PresentField::from_inner(Private, data))
-    } else {
-        Optional::Unset(AbsentField::from_inner(Private, data))
-    }
-}
-
-/// The internal implementation type for a vtable-based `protobuf::Mut<T>`.
-///
-/// This stores the two components necessary to mutate the field:
-/// borrowed message data and a vtable reference.
-///
-/// The borrowed message data varies per runtime: C++ needs a message pointer,
-/// while UPB needs a message pointer and an `&Arena`.
-///
-/// Implementations of `ProxiedWithRawVTable` implement get/set
-/// on top of `RawVTableMutator<T>`, and the top-level mutator (e.g.
-/// `BytesMut`) calls these methods.
-///
-/// [`RawVTableOptionalMutatorData`] is similar, but also includes the
-/// capability to has/clear.
-pub struct RawVTableMutator<'msg, T: ?Sized> {
-    msg_ref: MutatorMessageRef<'msg>,
-    /// Stores `&'static <T as ProxiedWithRawVTable>::Vtable`
-    /// as a type-erased pointer to avoid a bound on the struct.
-    vtable: NonNull<()>,
-    _phantom: PhantomData<&'msg T>,
-}
-
-// These use manual impls instead of derives to avoid unnecessary bounds on `T`.
-// This problem is referred to as "perfect derive".
-// https://smallcultfollowing.com/babysteps/blog/2022/04/12/implied-bounds-and-perfect-derive/
-impl<'msg, T: ?Sized> Clone for RawVTableMutator<'msg, T> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'msg, T: ?Sized> Copy for RawVTableMutator<'msg, T> {}
-
-impl<'msg, T: ProxiedWithRawVTable + ?Sized> Debug for RawVTableMutator<'msg, T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RawVTableMutator")
-            .field("msg_ref", &self.msg_ref)
-            .field("vtable", self.vtable())
-            .finish()
-    }
-}
-
-impl<'msg, T: ProxiedWithRawVTable + ?Sized> RawVTableMutator<'msg, T> {
-    /// # Safety
-    /// - `msg_ref` must be valid to provide as an argument for `vtable`'s
-    ///   methods for `'msg`.
-    /// - If given `msg_ref` as an argument, any values returned by `vtable`
-    ///   methods must be valid for `'msg`.
-    #[doc(hidden)]
-    pub unsafe fn new(
-        _private: Private,
-        msg_ref: MutatorMessageRef<'msg>,
-        vtable: &'static T::VTable,
-    ) -> Self {
-        RawVTableMutator { msg_ref, vtable: NonNull::from(vtable).cast(), _phantom: PhantomData }
-    }
-
-    pub fn vtable(self) -> &'static T::VTable {
-        // SAFETY: This was cast from `&'static T::VTable`.
-        unsafe { self.vtable.cast().as_ref() }
-    }
-
-    pub fn msg_ref(self) -> MutatorMessageRef<'msg> {
-        self.msg_ref
-    }
-}
-
-/// [`RawVTableMutator`], but also includes has/clear.
-///
-/// This is used as the `PresentData` and `AbsentData` for `impl
-/// ProxiedWithPresence for T`. In that implementation, `clear_present_field`
-/// and `set_absent_to_default` will use methods implemented on
-/// `RawVTableOptionalMutatorData<T>` to do the setting and clearing.
-///
-/// This has the same representation for "present" and "absent" data;
-/// differences like default values are obviated by the vtable.
-pub struct RawVTableOptionalMutatorData<'msg, T: ?Sized> {
-    msg_ref: MutatorMessageRef<'msg>,
-    /// Stores `&'static <T as ProxiedWithRawOptionalVTable>::Vtable`
-    /// as a type-erased pointer to avoid a bound on the struct.
-    optional_vtable: NonNull<()>,
-    _phantom: PhantomData<&'msg T>,
-}
-
-// SAFETY: all `T` that can perform mutations don't mutate through a shared
-// reference.
-unsafe impl<'msg, T: ?Sized> Sync for RawVTableOptionalMutatorData<'msg, T> {}
-
-// These use manual impls instead of derives to avoid unnecessary bounds on `T`.
-// This problem is referred to as "perfect derive".
-// https://smallcultfollowing.com/babysteps/blog/2022/04/12/implied-bounds-and-perfect-derive/
-impl<'msg, T: ?Sized> Clone for RawVTableOptionalMutatorData<'msg, T> {
-    fn clone(&self) -> Self {
-        *self
-    }
-}
-impl<'msg, T: ?Sized> Copy for RawVTableOptionalMutatorData<'msg, T> {}
-
-impl<'msg, T: ProxiedWithRawOptionalVTable + ?Sized> Debug
-    for RawVTableOptionalMutatorData<'msg, T>
-{
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_struct("RawVTableOptionalMutatorData")
-            .field("msg_ref", &self.msg_ref)
-            .field("vtable", self.optional_vtable())
-            .finish()
-    }
-}
-
-impl<'msg, T: ProxiedWithRawOptionalVTable + ?Sized> RawVTableOptionalMutatorData<'msg, T> {
-    /// # Safety
-    /// - `msg_ref` must be valid to provide as an argument for `vtable`'s
-    ///   methods for `'msg`.
-    /// - If given `msg_ref` as an argument, any values returned by `vtable`
-    ///   methods must be valid for `'msg`.
-    #[doc(hidden)]
-    pub unsafe fn new(
-        _private: Private,
-        msg_ref: MutatorMessageRef<'msg>,
-        vtable: &'static T::OptionalVTable,
-    ) -> Self {
-        Self { msg_ref, optional_vtable: NonNull::from(vtable).cast(), _phantom: PhantomData }
-    }
-
-    pub fn msg_ref(self) -> MutatorMessageRef<'msg> {
-        self.msg_ref
-    }
-
-    pub fn optional_vtable(self) -> &'static T::OptionalVTable {
-        // SAFETY: This was cast from `&'static T::OptionalVTable` in `new`.
-        unsafe { self.optional_vtable.cast().as_ref() }
-    }
-
-    fn into_raw_mut(self) -> RawVTableMutator<'msg, T> {
-        // SAFETY: the safety requirements have been met by the caller of `new`.
-        unsafe {
-            RawVTableMutator::new(
-                Private,
-                self.msg_ref,
-                T::upcast_vtable(Private, self.optional_vtable()),
-            )
-        }
-    }
-}
-
-impl<'msg, T: ProxiedWithRawOptionalVTable + ?Sized + 'msg> ViewProxy<'msg>
-    for RawVTableOptionalMutatorData<'msg, T>
-{
-    type Proxied = T;
-
-    fn as_view(&self) -> View<'_, T> {
-        T::make_view(Private, self.into_raw_mut())
-    }
-
-    fn into_view<'shorter>(self) -> View<'shorter, T>
-    where
-        'msg: 'shorter,
-    {
-        T::make_view(Private, self.into_raw_mut())
-    }
-}
-
-// Note: though this raw value implements `MutProxy`, the `as_mut` is only valid
-// when the field is known to be present. `FieldEntry` enforces this in its
-// design: `AbsentField { inner: RawVTableOptionalMutatorData<T> }` does not
-// implement `MutProxy`.
-impl<'msg, T: ProxiedWithRawOptionalVTable + ?Sized + 'msg> MutProxy<'msg>
-    for RawVTableOptionalMutatorData<'msg, T>
-{
-    fn as_mut(&mut self) -> Mut<'_, T> {
-        T::make_mut(Private, self.into_raw_mut())
-    }
-
-    fn into_mut<'shorter>(self) -> Mut<'shorter, T>
-    where
-        'msg: 'shorter,
-    {
-        T::make_mut(Private, self.into_raw_mut())
-    }
-}
-
-impl ProxiedWithRawVTable for [u8] {
-    type VTable = BytesMutVTable;
-
-    fn make_view(_private: Private, mut_inner: RawVTableMutator<'_, Self>) -> View<'_, Self> {
-        mut_inner.get()
-    }
-
-    fn make_mut(_private: Private, inner: RawVTableMutator<'_, Self>) -> Mut<'_, Self> {
-        crate::string::BytesMut::from_inner(Private, inner)
-    }
-}
-
-impl ProxiedWithRawOptionalVTable for [u8] {
-    type OptionalVTable = BytesOptionalMutVTable;
-    fn upcast_vtable(
-        _private: Private,
-        optional_vtable: &'static Self::OptionalVTable,
-    ) -> &'static Self::VTable {
-        &optional_vtable.base
-    }
-}
-
-/// A generic thunk vtable for mutating a present primitive field.
-#[doc(hidden)]
-#[derive(Debug)]
-pub struct PrimitiveVTable<T> {
-    pub(crate) setter: unsafe extern "C" fn(msg: RawMessage, val: T),
-    pub(crate) getter: unsafe extern "C" fn(msg: RawMessage) -> T,
-}
-
-#[doc(hidden)]
-#[derive(Debug)]
-/// A generic thunk vtable for mutating an `optional` primitive field.
-pub struct PrimitiveOptionalMutVTable<T> {
-    pub(crate) base: PrimitiveVTable<T>,
-    pub(crate) clearer: unsafe extern "C" fn(msg: RawMessage),
-    pub(crate) default: T,
-}
-
-impl<T> PrimitiveVTable<T> {
-    #[doc(hidden)]
-    pub const fn new(
-        _private: Private,
-        getter: unsafe extern "C" fn(msg: RawMessage) -> T,
-        setter: unsafe extern "C" fn(msg: RawMessage, val: T),
-    ) -> Self {
-        Self { getter, setter }
-    }
-}
-
-impl<T> PrimitiveOptionalMutVTable<T> {
-    #[doc(hidden)]
-    pub const fn new(
-        _private: Private,
-        getter: unsafe extern "C" fn(msg: RawMessage) -> T,
-        setter: unsafe extern "C" fn(msg: RawMessage, val: T),
-        clearer: unsafe extern "C" fn(msg: RawMessage),
-        default: T,
-    ) -> Self {
-        Self { base: PrimitiveVTable { getter, setter }, clearer, default }
-    }
-}
-
-/// A generic thunk vtable for mutating a present `bytes` or `string` field.
-#[doc(hidden)]
-#[derive(Debug)]
-pub struct BytesMutVTable {
-    pub(crate) setter: unsafe extern "C" fn(msg: RawMessage, val: PtrAndLen),
-    pub(crate) getter: unsafe extern "C" fn(msg: RawMessage) -> PtrAndLen,
-}
-
-/// A generic thunk vtable for mutating an `optional` `bytes` or `string` field.
-#[derive(Debug)]
-pub struct BytesOptionalMutVTable {
-    pub(crate) base: BytesMutVTable,
-    pub(crate) clearer: unsafe extern "C" fn(msg: RawMessage),
-    pub(crate) default: &'static [u8],
-}
-
-impl BytesMutVTable {
-    #[doc(hidden)]
-    pub const fn new(
-        _private: Private,
-        getter: unsafe extern "C" fn(msg: RawMessage) -> PtrAndLen,
-        setter: unsafe extern "C" fn(msg: RawMessage, val: PtrAndLen),
-    ) -> Self {
-        Self { getter, setter }
-    }
-}
-
-impl BytesOptionalMutVTable {
-    /// # Safety
-    /// The `default` value must be UTF-8 if required by
-    /// the runtime and this is for a `string` field.
-    #[doc(hidden)]
-    pub const unsafe fn new(
-        _private: Private,
-        getter: unsafe extern "C" fn(msg: RawMessage) -> PtrAndLen,
-        setter: unsafe extern "C" fn(msg: RawMessage, val: PtrAndLen),
-        clearer: unsafe extern "C" fn(msg: RawMessage),
-        default: &'static [u8],
-    ) -> Self {
-        Self { base: BytesMutVTable { getter, setter }, clearer, default }
-    }
-}
-
-impl<'msg> RawVTableMutator<'msg, [u8]> {
-    pub(crate) fn get(self) -> &'msg [u8] {
-        // SAFETY:
-        // - `msg_ref` is valid for `'msg` as promised by the caller of `new`.
-        // - The caller of `BytesMutVTable` promised that the returned `PtrAndLen` is
-        //   valid for `'msg`.
-        unsafe { (self.vtable().getter)(self.msg_ref.msg()).as_ref() }
-    }
-
-    /// # Safety
-    /// - `msg_ref` must be valid for `'msg`
-    /// - If this is for a `string` field, `val` must be valid UTF-8 if the
-    ///   runtime requires it.
-    pub(crate) unsafe fn set(self, val: &[u8]) {
-        let val = copy_bytes_in_arena_if_needed_by_runtime(self.msg_ref, val);
-        // SAFETY:
-        // - `msg_ref` is valid for `'msg` as promised by the caller of `new`.
-        unsafe { (self.vtable().setter)(self.msg_ref.msg(), val.into()) }
-    }
-
-    pub(crate) fn truncate(&self, len: usize) {
-        if len == 0 {
-            // SAFETY: The empty string is valid UTF-8.
-            unsafe {
-                self.set(b"");
-            }
-            return;
-        }
-        todo!("b/294252563")
-    }
-}
-
-impl<'msg> RawVTableOptionalMutatorData<'msg, [u8]> {
-    /// Sets an absent `bytes`/`string` field to its default value.
-    pub(crate) fn set_absent_to_default(self) -> Self {
-        // SAFETY: The default value is UTF-8 if required by the
-        // runtime as promised by the caller of `BytesOptionalMutVTable::new`.
-        unsafe { self.set(self.optional_vtable().default) }
-    }
-
-    /// # Safety
-    /// - If this is a `string` field, `val` must be valid UTF-8 if required by
-    ///   the runtime.
-    pub(crate) unsafe fn set(self, val: &[u8]) -> Self {
-        let val = copy_bytes_in_arena_if_needed_by_runtime(self.msg_ref, val);
-        // SAFETY:
-        // - `msg_ref` is valid for `'msg` as promised by the caller.
-        unsafe { (self.optional_vtable().base.setter)(self.msg_ref.msg(), val.into()) }
-        self
-    }
-
-    pub(crate) fn clear(self) -> Self {
-        // SAFETY:
-        // - `msg_ref` is valid for `'msg` as promised by the caller.
-        // - The caller of `new` promised that the returned `PtrAndLen` is valid for
-        //   `'msg`.
-        unsafe { (self.optional_vtable().clearer)(self.msg_ref.msg()) }
-        self
-    }
-}
-
-/// Primitive types using a vtable for message access that are trivial to copy
-/// and have a `'static` lifetime.
-///
-/// Implementing this trait automatically implements `ProxiedWithRawVTable`,
-/// `ProxiedWithRawOptionalVTable`, and get/set/clear methods on
-/// `RawVTableMutator` and `RawVTableOptionalMutatorData` that use the vtable.
-///
-/// It doesn't implement `Proxied`, `ViewProxy`, `SettableValue` or
-/// `ProxiedWithPresence` for `Self` to avoid future conflicting blanket impls
-/// on those traits.
-pub trait PrimitiveWithRawVTable:
-    Copy
-    + Debug
-    + 'static
-    + ProxiedWithPresence
-    + Sync
-    + Send
-    + for<'msg> Proxied<View<'msg> = Self, Mut<'msg> = PrimitiveMut<'msg, Self>>
-{
-}
-
-impl<T: PrimitiveWithRawVTable> ProxiedWithRawVTable for T {
-    type VTable = PrimitiveVTable<T>;
-
-    fn make_view(_private: Private, mut_inner: InnerPrimitiveMut<'_, Self>) -> Self {
-        mut_inner.get()
-    }
-
-    fn make_mut(_private: Private, inner: InnerPrimitiveMut<'_, Self>) -> PrimitiveMut<'_, Self> {
-        // SAFETY: `inner` is valid for the necessary lifetime and `T` as promised by
-        // the caller of `InnerPrimitiveMut::new`.
-        unsafe { PrimitiveMut::from_inner(Private, inner) }
-    }
-}
-
-impl<T: PrimitiveWithRawVTable> ProxiedWithRawOptionalVTable for T {
-    type OptionalVTable = PrimitiveOptionalMutVTable<T>;
-
-    fn upcast_vtable(
-        _private: Private,
-        optional_vtable: &'static Self::OptionalVTable,
-    ) -> &'static Self::VTable {
-        &optional_vtable.base
-    }
-}
-
-impl<T: PrimitiveWithRawVTable> RawVTableMutator<'_, T> {
-    pub(crate) fn get(self) -> T {
-        // SAFETY:
-        // - `msg_ref` is valid for the lifetime of `RawVTableMutator` as promised by
-        //   the caller of `new`.
-        unsafe { (self.vtable().getter)(self.msg_ref.msg()) }
-    }
-
-    /// # Safety
-    /// - `msg_ref` must be valid for the lifetime of `RawVTableMutator`.
-    pub(crate) unsafe fn set(self, val: T) {
-        // SAFETY:
-        // - `msg_ref` is valid for the lifetime of `RawVTableMutator` as promised by
-        //   the caller of `new`.
-        unsafe { (self.vtable().setter)(self.msg_ref.msg(), val) }
-    }
-}
-
-impl<'msg, T: PrimitiveWithRawVTable> RawVTableOptionalMutatorData<'msg, T> {
-    pub fn set_absent_to_default(self, private: Private) -> Self {
-        // SAFETY:
-        // - `msg_ref` is valid for the lifetime of `RawVTableOptionalMutatorData` as
-        //   promised by the caller of `new`.
-        self.set(private, self.optional_vtable().default)
-    }
-
-    pub fn set(self, _private: Private, val: T) -> Self {
-        // SAFETY:
-        // - `msg_ref` is valid for the lifetime of `RawVTableOptionalMutatorData` as
-        //   promised by the caller of `new`.
-        unsafe { (self.optional_vtable().base.setter)(self.msg_ref.msg(), val) }
-        self
-    }
-
-    pub fn clear(self, _private: Private) -> Self {
-        // SAFETY:
-        // - `msg_ref` is valid for the lifetime of `RawVTableOptionalMutatorData` as
-        //   promised by the caller of `new`.
-        unsafe { (self.optional_vtable().clearer)(self.msg_ref.msg()) }
-        self
-    }
-}
diff --git a/src/file_lists.cmake b/src/file_lists.cmake
index 345d44bf5e..b69fcef7e4 100644
--- a/src/file_lists.cmake
+++ b/src/file_lists.cmake
@@ -332,27 +332,28 @@ set(libprotoc_srcs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/doc_comment.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/field_common.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/file.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/enum.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/enum_field.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/extension.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/generator_factory.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/make_field_gens.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/map_field.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/message.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/message_builder.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/message_field.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/primitive_field.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/service.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/string_field.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/generator.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/helpers.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/enum.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/enum_field.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/extension.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/generator_factory.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/make_field_generators.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/map_field.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/message.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/message_builder.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/message_field.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/primitive_field.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/service.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/string_field.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/internal_helpers.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/java_features.pb.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/kotlin_generator.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/enum.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/enum_field.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/extension.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/generator_factory.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/make_field_generators.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/make_field_gens.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/map_field.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/message.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/message_builder.cc
@@ -378,7 +379,7 @@ set(libprotoc_srcs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/names.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/oneof.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/primitive_field.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/text_format_decode_data.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/tf_decode_data.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/php/names.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/php/php_generator.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/plugin.cc
@@ -390,7 +391,7 @@ set(libprotoc_srcs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/ruby/ruby_generator.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/accessor_case.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/accessors.cc
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/helpers.cc
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/default_value.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/map.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/repeated_field.cc
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/singular_message.cc
@@ -457,23 +458,24 @@ set(libprotoc_hdrs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/doc_comment.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/field_common.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/file.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/enum.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/enum_field.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/extension.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/field_generator.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/generator_factory.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/make_field_gens.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/map_field.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/message.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/message_builder.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/message_field.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/primitive_field.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/service.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/full/string_field.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/generator_common.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/generator_factory.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/helpers.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/enum.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/enum_field.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/extension.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/field_generator.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/generator_factory.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/make_field_generators.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/map_field.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/message.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/message_builder.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/message_field.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/primitive_field.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/service.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/immutable/string_field.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/internal_helpers.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/java_features.pb.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/kotlin_generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/enum.h
@@ -481,7 +483,7 @@ set(libprotoc_hdrs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/extension.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/field_generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/generator_factory.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/make_field_generators.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/make_field_gens.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/map_field.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/message.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/java/lite/message_builder.h
@@ -510,7 +512,7 @@ set(libprotoc_hdrs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/oneof.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/options.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/primitive_field.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/text_format_decode_data.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/objectivec/tf_decode_data.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/php/names.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/php/php_generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/plugin.h
@@ -521,9 +523,9 @@ set(libprotoc_hdrs
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/retention.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/ruby/ruby_generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/accessor_case.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/accessor_generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/accessors.h
-  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/helpers.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/default_value.h
+  ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/accessors/generator.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/context.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/crate_mapping.h
   ${protobuf_SOURCE_DIR}/src/google/protobuf/compiler/rust/enum.h
diff --git a/src/google/protobuf/BUILD.bazel b/src/google/protobuf/BUILD.bazel
index 917d9d35d0..56d25c309b 100644
--- a/src/google/protobuf/BUILD.bazel
+++ b/src/google/protobuf/BUILD.bazel
@@ -840,6 +840,16 @@ filegroup(
     visibility = ["//:__subpackages__"],
 )
 
+filegroup(
+    name = "unittest_proto_srcs",
+    srcs = [
+        "unittest.proto",
+        "unittest_import.proto",
+        "unittest_import_public.proto",
+    ],
+    visibility = ["//:__subpackages__"],
+)
+
 filegroup(
     name = "test_proto_editions_srcs",
     srcs = [
@@ -1185,6 +1195,7 @@ cc_test(
     }),
     deps = [
         ":arena",
+        ":arena_cleanup",
         ":cc_test_protos",
         ":lite_test_util",
         ":port",
diff --git a/src/google/protobuf/any.pb.cc b/src/google/protobuf/any.pb.cc
index c9b4ba0b23..1d70e242ad 100644
--- a/src/google/protobuf/any.pb.cc
+++ b/src/google/protobuf/any.pb.cc
@@ -280,26 +280,27 @@ PROTOBUF_NOINLINE void Any::Clear() {
 }
 
 ::size_t Any::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Any)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Any)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
-
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // string type_url = 1;
-  if (!this->_internal_type_url().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_type_url());
-  }
+  (void)cached_has_bits;
 
-  // bytes value = 2;
-  if (!this->_internal_value().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::BytesSize(
-                                    this->_internal_value());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // string type_url = 1;
+    if (!this->_internal_type_url().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_type_url());
+    }
+    // bytes value = 2;
+    if (!this->_internal_value().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::BytesSize(
+                                      this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/src/google/protobuf/api.pb.cc b/src/google/protobuf/api.pb.cc
index d24dd96095..1d572b11d1 100644
--- a/src/google/protobuf/api.pb.cc
+++ b/src/google/protobuf/api.pb.cc
@@ -508,54 +508,65 @@ PROTOBUF_NOINLINE void Api::Clear() {
 }
 
 ::size_t Api::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Api)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Api)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.Method methods = 2;
-  total_size += 1UL * this->_internal_methods_size();
-  for (const auto& msg : this->_internal_methods()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.Option options = 3;
-  total_size += 1UL * this->_internal_options_size();
-  for (const auto& msg : this->_internal_options()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.Mixin mixins = 6;
-  total_size += 1UL * this->_internal_mixins_size();
-  for (const auto& msg : this->_internal_mixins()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.Method methods = 2;
+     {
+      total_size += 1UL * this->_internal_methods_size();
+      for (const auto& msg : this->_internal_methods()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.Option options = 3;
+     {
+      total_size += 1UL * this->_internal_options_size();
+      for (const auto& msg : this->_internal_options()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.Mixin mixins = 6;
+     {
+      total_size += 1UL * this->_internal_mixins_size();
+      for (const auto& msg : this->_internal_mixins()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-
-  // string version = 4;
-  if (!this->_internal_version().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_version());
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // string version = 4;
+    if (!this->_internal_version().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_version());
+    }
   }
-
-  // .google.protobuf.SourceContext source_context = 5;
-  cached_has_bits = _impl_._has_bits_[0];
-  if (cached_has_bits & 0x00000001u) {
-    total_size +=
-        1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_context_);
+   {
+    // .google.protobuf.SourceContext source_context = 5;
+    cached_has_bits = _impl_._has_bits_[0];
+    if (cached_has_bits & 0x00000001u) {
+      total_size +=
+          1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_context_);
+    }
   }
-
-  // .google.protobuf.Syntax syntax = 7;
-  if (this->_internal_syntax() != 0) {
-    total_size += 1 +
-                  ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+   {
+    // .google.protobuf.Syntax syntax = 7;
+    if (this->_internal_syntax() != 0) {
+      total_size += 1 +
+                    ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -888,53 +899,54 @@ PROTOBUF_NOINLINE void Method::Clear() {
 }
 
 ::size_t Method::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Method)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Method)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
-
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.Option options = 6;
-  total_size += 1UL * this->_internal_options_size();
-  for (const auto& msg : this->_internal_options()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
-  }
-
-  // string request_type_url = 2;
-  if (!this->_internal_request_type_url().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_request_type_url());
-  }
-
-  // string response_type_url = 4;
-  if (!this->_internal_response_type_url().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_response_type_url());
-  }
-
-  // bool request_streaming = 3;
-  if (this->_internal_request_streaming() != 0) {
-    total_size += 2;
-  }
+  (void)cached_has_bits;
 
-  // bool response_streaming = 5;
-  if (this->_internal_response_streaming() != 0) {
-    total_size += 2;
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.Option options = 6;
+     {
+      total_size += 1UL * this->_internal_options_size();
+      for (const auto& msg : this->_internal_options()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-
-  // .google.protobuf.Syntax syntax = 7;
-  if (this->_internal_syntax() != 0) {
-    total_size += 1 +
-                  ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // string request_type_url = 2;
+    if (!this->_internal_request_type_url().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_request_type_url());
+    }
+    // string response_type_url = 4;
+    if (!this->_internal_response_type_url().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_response_type_url());
+    }
+    // bool request_streaming = 3;
+    if (this->_internal_request_streaming() != 0) {
+      total_size += 2;
+    }
+    // bool response_streaming = 5;
+    if (this->_internal_response_streaming() != 0) {
+      total_size += 2;
+    }
+    // .google.protobuf.Syntax syntax = 7;
+    if (this->_internal_syntax() != 0) {
+      total_size += 1 +
+                    ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1159,26 +1171,27 @@ PROTOBUF_NOINLINE void Mixin::Clear() {
 }
 
 ::size_t Mixin::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Mixin)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Mixin)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
-
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
-  }
+  (void)cached_has_bits;
 
-  // string root = 2;
-  if (!this->_internal_root().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_root());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // string root = 2;
+    if (!this->_internal_root().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_root());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/src/google/protobuf/arena.cc b/src/google/protobuf/arena.cc
index e4fa0cea45..55d87ab6bb 100644
--- a/src/google/protobuf/arena.cc
+++ b/src/google/protobuf/arena.cc
@@ -60,34 +60,49 @@ ArenaBlock* SentryArenaBlock() {
 }
 #endif
 
-SizedPtr AllocateMemory(const AllocationPolicy* policy_ptr, size_t last_size,
-                        size_t min_bytes) {
+inline size_t AllocationSize(size_t last_size, size_t start_size,
+                             size_t max_size) {
+  if (last_size == 0) return start_size;
+  // Double the current block size, up to a limit.
+  return std::min(2 * last_size, max_size);
+}
+
+SizedPtr AllocateMemory(const AllocationPolicy& policy, size_t size) {
+  if (policy.block_alloc == nullptr) {
+    return AllocateAtLeast(size);
+  }
+  return {policy.block_alloc(size), size};
+}
+
+SizedPtr AllocateBlock(const AllocationPolicy* policy_ptr, size_t last_size,
+                       size_t min_bytes) {
   AllocationPolicy policy;  // default policy
   if (policy_ptr) policy = *policy_ptr;
-  size_t size;
-  if (last_size != 0) {
-    // Double the current block size, up to a limit.
-    auto max_size = policy.max_block_size;
-    size = std::min(2 * last_size, max_size);
-  } else {
-    size = policy.start_block_size;
-  }
+  size_t size =
+      AllocationSize(last_size, policy.start_block_size, policy.max_block_size);
   // Verify that min_bytes + kBlockHeaderSize won't overflow.
   ABSL_CHECK_LE(min_bytes, std::numeric_limits<size_t>::max() -
                                SerialArena::kBlockHeaderSize);
   size = std::max(size, SerialArena::kBlockHeaderSize + min_bytes);
 
-  if (policy.block_alloc == nullptr) {
-    return AllocateAtLeast(size);
-  }
-  return {policy.block_alloc(size), size};
+  return AllocateMemory(policy, size);
+}
+
+SizedPtr AllocateCleanupChunk(const AllocationPolicy* policy_ptr,
+                              size_t last_size) {
+  constexpr size_t kStartSize = 64;
+  constexpr size_t kMaxSize = 4 << 10;
+  static_assert(kStartSize % sizeof(cleanup::CleanupNode) == 0, "");
+
+  const size_t size = AllocationSize(last_size, kStartSize, kMaxSize);
+  if (policy_ptr == nullptr) return AllocateAtLeast(size);
+  return AllocateMemory(*policy_ptr, size);
 }
 
 class GetDeallocator {
  public:
-  GetDeallocator(const AllocationPolicy* policy, size_t* space_allocated)
-      : dealloc_(policy ? policy->block_dealloc : nullptr),
-        space_allocated_(space_allocated) {}
+  explicit GetDeallocator(const AllocationPolicy* policy)
+      : dealloc_(policy ? policy->block_dealloc : nullptr) {}
 
   void operator()(SizedPtr mem) const {
     if (dealloc_) {
@@ -95,18 +110,96 @@ class GetDeallocator {
     } else {
       internal::SizedDelete(mem.p, mem.n);
     }
-    AddSpaceAllocated(mem.n);
   }
 
-  void AddSpaceAllocated(size_t n) const { *space_allocated_ += n; }
-
  private:
   void (*dealloc_)(void*, size_t);
-  size_t* space_allocated_;
 };
 
 }  // namespace
 
+namespace cleanup {
+struct ChunkList::Chunk {
+  CleanupNode* First() { return reinterpret_cast<CleanupNode*>(this + 1); }
+  CleanupNode* Last() { return First() + Capacity() - 1; }
+  static size_t Capacity(size_t size) {
+    return (size - sizeof(Chunk)) / sizeof(CleanupNode);
+  }
+  size_t Capacity() const { return Capacity(size); }
+
+  Chunk* next;
+  size_t size;
+  // Cleanup nodes follow.
+};
+
+void ChunkList::AddFallback(void* elem, void (*destructor)(void*),
+                            SerialArena& arena) {
+  ABSL_DCHECK_EQ(next_, limit_);
+  SizedPtr mem = AllocateCleanupChunk(arena.parent_.AllocPolicy(),
+                                      head_ == nullptr ? 0 : head_->size);
+  arena.AddSpaceAllocated(mem.n);
+  head_ = new (mem.p) Chunk{head_, mem.n};
+  next_ = head_->First();
+  prefetch_ptr_ = reinterpret_cast<char*>(next_);
+  limit_ = next_ + Chunk::Capacity(mem.n);
+  AddFromExisting(elem, destructor);
+}
+
+void ChunkList::Cleanup(const SerialArena& arena) {
+  Chunk* c = head_;
+  if (c == nullptr) return;
+  GetDeallocator deallocator(arena.parent_.AllocPolicy());
+
+  // Iterate backwards in order to destroy in the right order.
+  CleanupNode* it = next_ - 1;
+  while (true) {
+    CleanupNode* first = c->First();
+    // A prefetch distance of 8 here was chosen arbitrarily.
+    constexpr int kPrefetchDistance = 8;
+    CleanupNode* prefetch = it;
+    // Prefetch the first kPrefetchDistance nodes.
+    for (int i = 0; prefetch >= first && i < kPrefetchDistance;
+         --prefetch, ++i) {
+      prefetch->Prefetch();
+    }
+    // For the middle nodes, run destructor and prefetch the node
+    // kPrefetchDistance after the current one.
+    for (; prefetch >= first; --it, --prefetch) {
+      it->Destroy();
+      prefetch->Prefetch();
+    }
+    // Note: we could consider prefetching `next` chunk earlier.
+    absl::PrefetchToLocalCacheNta(c->next);
+    // Destroy the rest without prefetching.
+    for (; it >= first; --it) {
+      it->Destroy();
+    }
+    Chunk* next = c->next;
+    deallocator({c, c->size});
+    if (next == nullptr) return;
+    c = next;
+    it = c->Last();
+  };
+}
+
+std::vector<void*> ChunkList::PeekForTesting() {
+  std::vector<void*> ret;
+  Chunk* c = head_;
+  if (c == nullptr) return ret;
+  // Iterate backwards to match destruction order.
+  CleanupNode* it = next_ - 1;
+  while (true) {
+    CleanupNode* first = c->First();
+    for (; it >= first; --it) {
+      ret.push_back(it->elem);
+    }
+    c = c->next;
+    if (c == nullptr) return ret;
+    it = c->Last();
+  };
+}
+}  // namespace cleanup
+
 // It is guaranteed that this is constructed in `b`. IOW, this is not the first
 // arena and `b` cannot be sentry.
 SerialArena::SerialArena(ArenaBlock* b, ThreadSafeArena& parent)
@@ -114,7 +207,6 @@ SerialArena::SerialArena(ArenaBlock* b, ThreadSafeArena& parent)
       limit_{b->Limit()},
       prefetch_ptr_(
           b->Pointer(kBlockHeaderSize + ThreadSafeArena::kSerialArenaSize)),
-      prefetch_limit_(b->Limit()),
       head_{b},
       space_allocated_{b->size},
       parent_{parent} {
@@ -135,22 +227,7 @@ SerialArena::SerialArena(FirstSerialArena, ArenaBlock* b,
 }
 
 std::vector<void*> SerialArena::PeekCleanupListForTesting() {
-  std::vector<void*> res;
-
-  ArenaBlock* b = head();
-  if (b->IsSentry()) return res;
-
-  const auto peek_list = [&](char* pos, char* end) {
-    for (; pos != end; pos += cleanup::Size()) {
-      cleanup::PeekNode(pos, res);
-    }
-  };
-
-  peek_list(limit_, b->Limit());
-  for (b = b->next; b; b = b->next) {
-    peek_list(reinterpret_cast<char*>(b->cleanup_nodes), b->Limit());
-  }
-  return res;
+  return cleanup_list_.PeekForTesting();
 }
 
 std::vector<void*> ThreadSafeArena::PeekCleanupListForTesting() {
@@ -179,7 +256,7 @@ SerialArena* SerialArena::New(SizedPtr mem, ThreadSafeArena& parent) {
 
 template <typename Deallocator>
 SizedPtr SerialArena::Free(Deallocator deallocator) {
-  deallocator.AddSpaceAllocated(FreeStringBlocks());
+  FreeStringBlocks();
 
   ArenaBlock* b = head();
   SizedPtr mem = {b, b->size};
@@ -228,25 +305,16 @@ void* SerialArena::AllocateFromStringBlockFallback() {
 PROTOBUF_NOINLINE
 void* SerialArena::AllocateAlignedWithCleanupFallback(
     size_t n, size_t align, void (*destructor)(void*)) {
-  size_t required = AlignUpTo(n, align) + cleanup::Size();
+  size_t required = AlignUpTo(n, align);
   AllocateNewBlock(required);
   return AllocateAlignedWithCleanup(n, align, destructor);
 }
 
-PROTOBUF_NOINLINE
-void SerialArena::AddCleanupFallback(void* elem, void (*destructor)(void*)) {
-  AllocateNewBlock(cleanup::Size());
-  AddCleanupFromExisting(elem, destructor);
-}
-
 void SerialArena::AllocateNewBlock(size_t n) {
   size_t used = 0;
   size_t wasted = 0;
   ArenaBlock* old_head = head();
   if (!old_head->IsSentry()) {
-    // Sync limit to block
-    old_head->cleanup_nodes = limit_;
-
     // Record how much used in this block.
     used = static_cast<size_t>(ptr() - old_head->Pointer(kBlockHeaderSize));
     wasted = old_head->size - used - kBlockHeaderSize;
@@ -258,7 +326,7 @@ void SerialArena::AllocateNewBlock(size_t n) {
   // but with a CPU regression. The regression might have been an artifact of
   // the microbenchmark.
 
-  auto mem = AllocateMemory(parent_.AllocPolicy(), old_head->size, n);
+  auto mem = AllocateBlock(parent_.AllocPolicy(), old_head->size, n);
   AddSpaceAllocated(mem.n);
   ThreadSafeArenaStats::RecordAllocateStats(parent_.arena_stats_.MutableStats(),
                                             /*used=*/used,
@@ -319,34 +387,6 @@ size_t SerialArena::FreeStringBlocks(StringBlock* string_block,
   return deallocated;
 }
 
-void SerialArena::CleanupList() {
-  ArenaBlock* b = head();
-  if (b->IsSentry()) return;
-
-  b->cleanup_nodes = limit_;
-  do {
-    char* limit = b->Limit();
-    char* it = reinterpret_cast<char*>(b->cleanup_nodes);
-    ABSL_DCHECK(!b->IsSentry() || it == limit);
-    // A prefetch distance of 8 here was chosen arbitrarily.
-    char* prefetch = it;
-    int prefetch_dist = 8;
-    for (; prefetch < limit && --prefetch_dist; prefetch += cleanup::Size()) {
-      cleanup::PrefetchNode(prefetch);
-    }
-    for (; prefetch < limit;
-         it += cleanup::Size(), prefetch += cleanup::Size()) {
-      cleanup::DestroyNode(it);
-      cleanup::PrefetchNode(prefetch);
-    }
-    absl::PrefetchToLocalCacheNta(b->next);
-    for (; it < limit; it += cleanup::Size()) {
-      cleanup::DestroyNode(it);
-    }
-    b = b->next;
-  } while (b);
-}
-
 // Stores arrays of void* and SerialArena* instead of linked list of
 // SerialArena* to speed up traversing all SerialArena. The cost of walk is non
 // trivial when there are many nodes. Separately storing "ids" minimizes cache
@@ -378,16 +418,21 @@ struct SerialArenaChunkHeader {
 class ThreadSafeArena::SerialArenaChunk {
  public:
   SerialArenaChunk(uint32_t capacity, void* me, SerialArena* serial) {
-    new (&header()) SerialArenaChunkHeader{capacity, 1};
+    // We use `layout`/`ids`/`arenas` local variables to avoid recomputing
+    // offsets if we were to call id(i)/arena(i) repeatedly.
+    const layout_type layout = Layout(capacity);
+    new (layout.Pointer<kHeader>(ptr())) SerialArenaChunkHeader{capacity, 1};
 
-    new (&id(0)) std::atomic<void*>{me};
+    std::atomic<void*>* ids = layout.Pointer<kIds>(ptr());
+    new (&ids[0]) std::atomic<void*>{me};
     for (uint32_t i = 1; i < capacity; ++i) {
-      new (&id(i)) std::atomic<void*>{nullptr};
+      new (&ids[i]) std::atomic<void*>{nullptr};
     }
 
-    new (&arena(0)) std::atomic<SerialArena*>{serial};
+    std::atomic<SerialArena*>* arenas = layout.Pointer<kArenas>(ptr());
+    new (&arenas[0]) std::atomic<SerialArena*>{serial};
     for (uint32_t i = 1; i < capacity; ++i) {
-      new (&arena(i)) std::atomic<void*>{nullptr};
+      new (&arenas[i]) std::atomic<SerialArena*>{nullptr};
     }
   }
 
@@ -406,30 +451,30 @@ class ThreadSafeArena::SerialArenaChunk {
 
   // ids: returns up to size().
   absl::Span<const std::atomic<void*>> ids() const {
-    return Layout(capacity()).Slice<kIds>(ptr()).first(safe_size());
+    return Layout().Slice<kIds>(ptr()).first(safe_size());
   }
   absl::Span<std::atomic<void*>> ids() {
-    return Layout(capacity()).Slice<kIds>(ptr()).first(safe_size());
+    return Layout().Slice<kIds>(ptr()).first(safe_size());
   }
   std::atomic<void*>& id(uint32_t i) {
     ABSL_DCHECK_LT(i, capacity());
-    return Layout(capacity()).Pointer<kIds>(ptr())[i];
+    return Layout().Pointer<kIds>(ptr())[i];
   }
 
   // arenas: returns up to size().
   absl::Span<const std::atomic<SerialArena*>> arenas() const {
-    return Layout(capacity()).Slice<kArenas>(ptr()).first(safe_size());
+    return Layout().Slice<kArenas>(ptr()).first(safe_size());
   }
   absl::Span<std::atomic<SerialArena*>> arenas() {
-    return Layout(capacity()).Slice<kArenas>(ptr()).first(safe_size());
+    return Layout().Slice<kArenas>(ptr()).first(safe_size());
   }
   const std::atomic<SerialArena*>& arena(uint32_t i) const {
     ABSL_DCHECK_LT(i, capacity());
-    return Layout(capacity()).Pointer<kArenas>(ptr())[i];
+    return Layout().Pointer<kArenas>(ptr())[i];
   }
   std::atomic<SerialArena*>& arena(uint32_t i) {
     ABSL_DCHECK_LT(i, capacity());
-    return Layout(capacity()).Pointer<kArenas>(ptr())[i];
+    return Layout().Pointer<kArenas>(ptr())[i];
   }
 
   // Tries to insert {id, serial} to head chunk. Returns false if the head is
@@ -486,6 +531,7 @@ class ThreadSafeArena::SerialArenaChunk {
   constexpr static layout_type Layout(size_t n) {
     return layout_type(/*header*/ 1, /*ids*/ n, /*arenas*/ n);
   }
+  layout_type Layout() const { return Layout(capacity()); }
 };
 
 constexpr SerialArenaChunkHeader kSentryArenaChunk = {0, 0};
@@ -549,7 +595,7 @@ ArenaBlock* ThreadSafeArena::FirstBlock(void* buf, size_t size,
 
   SizedPtr mem;
   if (buf == nullptr || size < kBlockHeaderSize + kAllocPolicySize) {
-    mem = AllocateMemory(&policy, 0, kAllocPolicySize);
+    mem = AllocateBlock(&policy, 0, kAllocPolicySize);
   } else {
     mem = {buf, size};
     // Record user-owned block.
@@ -692,19 +738,17 @@ ThreadSafeArena::~ThreadSafeArena() {
   // refer to memory in other blocks.
   CleanupList();
 
-  size_t space_allocated = 0;
-  auto mem = Free(&space_allocated);
+  auto mem = Free();
   if (alloc_policy_.is_user_owned_initial_block()) {
     // Unpoison the initial block, now that it's going back to the user.
     PROTOBUF_UNPOISON_MEMORY_REGION(mem.p, mem.n);
-    space_allocated += mem.n;
   } else if (mem.n > 0) {
-    GetDeallocator(alloc_policy_.get(), &space_allocated)(mem);
+    GetDeallocator(alloc_policy_.get())(mem);
   }
 }
 
-SizedPtr ThreadSafeArena::Free(size_t* space_allocated) {
-  auto deallocator = GetDeallocator(alloc_policy_.get(), space_allocated);
+SizedPtr ThreadSafeArena::Free() {
+  auto deallocator = GetDeallocator(alloc_policy_.get());
 
   WalkSerialArenaChunk([&](SerialArenaChunk* chunk) {
     absl::Span<std::atomic<SerialArena*>> span = chunk->arenas();
@@ -730,15 +774,17 @@ SizedPtr ThreadSafeArena::Free(size_t* space_allocated) {
 }
 
 uint64_t ThreadSafeArena::Reset() {
+  const size_t space_allocated = SpaceAllocated();
+
   // Have to do this in a first pass, because some of the destructors might
   // refer to memory in other blocks.
   CleanupList();
+  // Reset the first arena's cleanup list.
+  first_arena_.cleanup_list_ = cleanup::ChunkList();
 
   // Discard all blocks except the first one. Whether it is user-provided or
   // allocated, always reuse the first block for the first arena.
-  size_t space_allocated = 0;
-  auto mem = Free(&space_allocated);
-  space_allocated += mem.n;
+  auto mem = Free();
 
   // Reset the first arena with the first block. This avoids redundant
   // free / allocation and re-allocating for AllocationPolicy. Adjust offset if
@@ -914,7 +960,7 @@ SerialArena* ThreadSafeArena::GetSerialArenaFallback(size_t n) {
     // have any blocks yet.  So we'll allocate its first block now. It must be
     // big enough to host SerialArena and the pending request.
     serial = SerialArena::New(
-        AllocateMemory(alloc_policy_.get(), 0, n + kSerialArenaSize), *this);
+        AllocateBlock(alloc_policy_.get(), 0, n + kSerialArenaSize), *this);
 
     AddSerialArena(id, serial);
   }
diff --git a/src/google/protobuf/arena.h b/src/google/protobuf/arena.h
index c8ccfe24a1..f32f6d8c18 100644
--- a/src/google/protobuf/arena.h
+++ b/src/google/protobuf/arena.h
@@ -142,7 +142,7 @@ struct ArenaOptions {
 // This is a thread-safe implementation: multiple threads may allocate from the
 // arena concurrently. Destruction is not thread-safe and the destructing
 // thread must synchronize with users of the arena first.
-class PROTOBUF_EXPORT PROTOBUF_ALIGNAS(8) Arena final {
+class PROTOBUF_EXPORT alignas(8) Arena final {
  public:
   // Default constructor with sensible default options, tuned for average
   // use-cases.
diff --git a/src/google/protobuf/arena_cleanup.h b/src/google/protobuf/arena_cleanup.h
index abd2b73349..a153e36667 100644
--- a/src/google/protobuf/arena_cleanup.h
+++ b/src/google/protobuf/arena_cleanup.h
@@ -21,6 +21,9 @@
 namespace google {
 namespace protobuf {
 namespace internal {
+
+class SerialArena;
+
 namespace cleanup {
 
 // Helper function invoking the destructor of `object`
@@ -33,44 +36,61 @@ void arena_destruct_object(void* object) {
 // destroyed, and the function to destroy it (`destructor`)
 // elem must be aligned at minimum on a 4 byte boundary.
 struct CleanupNode {
+  // Optimization: performs a prefetch on the elem for the cleanup node. We
+  // explicitly use NTA prefetch here to avoid polluting remote caches: we are
+  // destroying these instances, there is no purpose for these cache lines to
+  // linger around in remote caches.
+  ABSL_ATTRIBUTE_ALWAYS_INLINE void Prefetch() {
+    // TODO: we should also prefetch the destructor code once
+    // processors support code prefetching.
+    absl::PrefetchToLocalCacheNta(elem);
+  }
+
+  // Destroys the object referenced by the cleanup node.
+  ABSL_ATTRIBUTE_ALWAYS_INLINE void Destroy() { destructor(elem); }
+
   void* elem;
   void (*destructor)(void*);
 };
 
-inline ABSL_ATTRIBUTE_ALWAYS_INLINE CleanupNode* ToCleanup(void* pos) {
-  return reinterpret_cast<CleanupNode*>(pos);
-}
-
-// Adds a cleanup entry at memory location `pos`.
-inline ABSL_ATTRIBUTE_ALWAYS_INLINE void CreateNode(void* pos, void* elem,
+// Manages the list of cleanup nodes in a chunked linked list. Chunks grow by
+// factors of two up to a limit. Trivially destructible, but Cleanup() must be
+// called before destruction.
+class ChunkList {
+ public:
+  PROTOBUF_ALWAYS_INLINE void Add(void* elem, void (*destructor)(void*),
+                                  SerialArena& arena) {
+    if (PROTOBUF_PREDICT_TRUE(next_ < limit_)) {
+      AddFromExisting(elem, destructor);
+      return;
+    }
+    AddFallback(elem, destructor, arena);
+  }
+
+  // Runs all inserted cleanups and frees allocated chunks. Must be called
+  // before destruction.
+  void Cleanup(const SerialArena& arena);
+
+ private:
+  struct Chunk;
+  friend class internal::SerialArena;
+
+  void AddFallback(void* elem, void (*destructor)(void*), SerialArena& arena);
+  ABSL_ATTRIBUTE_ALWAYS_INLINE void AddFromExisting(void* elem,
                                                     void (*destructor)(void*)) {
-  CleanupNode n = {elem, destructor};
-  memcpy(pos, &n, sizeof(n));
-}
-
-// Optimization: performs a prefetch on the elem for the cleanup node at `pos`.
-inline ABSL_ATTRIBUTE_ALWAYS_INLINE void PrefetchNode(void* pos) {
-  // We explicitly use NTA prefetch here to avoid polluting remote caches: we
-  // are destroying these instances, there is no purpose for these cache lines
-  // to linger around in remote caches.
-  absl::PrefetchToLocalCacheNta(ToCleanup(pos)->elem);
-}
-
-// Destroys the object referenced by the cleanup node.
-inline ABSL_ATTRIBUTE_ALWAYS_INLINE void DestroyNode(void* pos) {
-  CleanupNode* cleanup = ToCleanup(pos);
-  cleanup->destructor(cleanup->elem);
-}
-
-// Append in `out` the pointer to the to-be-cleaned object in `pos`.
-inline void PeekNode(void* pos, std::vector<void*>& out) {
-  out.push_back(ToCleanup(pos)->elem);
-}
-
-// Returns the required size for a cleanup node.
-constexpr ABSL_ATTRIBUTE_ALWAYS_INLINE size_t Size() {
-  return sizeof(CleanupNode);
-}
+    *next_++ = CleanupNode{elem, destructor};
+  }
+
+  // Returns the pointers to the to-be-cleaned objects.
+  std::vector<void*> PeekForTesting();
+
+  Chunk* head_ = nullptr;
+  CleanupNode* next_ = nullptr;
+  CleanupNode* limit_ = nullptr;
+  // Current prefetch position. Data from `next_` up to but not including
+  // `prefetch_ptr_` is software prefetched. Used in SerialArena prefetching.
+  const char* prefetch_ptr_ = nullptr;
+};
 
 }  // namespace cleanup
 }  // namespace internal
diff --git a/src/google/protobuf/arena_unittest.cc b/src/google/protobuf/arena_unittest.cc
index 0752735a48..3cc55c93b0 100644
--- a/src/google/protobuf/arena_unittest.cc
+++ b/src/google/protobuf/arena_unittest.cc
@@ -31,6 +31,7 @@
 #include "absl/strings/string_view.h"
 #include "absl/synchronization/barrier.h"
 #include "absl/utility/utility.h"
+#include "google/protobuf/arena_cleanup.h"
 #include "google/protobuf/arena_test_util.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/extension_set.h"
@@ -1406,12 +1407,12 @@ TEST(ArenaTest, RepeatedFieldOnArena) {
   // Preallocate an initial arena block to avoid mallocs during hooked region.
   std::vector<char> arena_block(1024 * 1024);
   Arena arena(arena_block.data(), arena_block.size());
+  const size_t initial_allocated_size = arena.SpaceAllocated();
 
   {
-    internal::NoHeapChecker no_heap;
-
-    // Fill some repeated fields on the arena to test for leaks. Also verify no
-    // memory allocations.
+    // Fill some repeated fields on the arena to test for leaks. Also that the
+    // newly allocated memory is approximately the size of the cleanups for the
+    // repeated messages.
     RepeatedField<int32_t> repeated_int32(&arena);
     RepeatedPtrField<TestAllTypes> repeated_message(&arena);
     for (int i = 0; i < 100; i++) {
@@ -1432,10 +1433,14 @@ TEST(ArenaTest, RepeatedFieldOnArena) {
     repeated_message.UnsafeArenaExtractSubrange(0, 5, extracted_messages);
     EXPECT_EQ(&arena, repeated_message.Get(0).GetArena());
     EXPECT_EQ(5, repeated_message.size());
+    // Upper bound of the size of the cleanups of new repeated messages.
+    const size_t upperbound_cleanup_size =
+        2 * 110 * sizeof(internal::cleanup::CleanupNode);
+    EXPECT_GT(initial_allocated_size + upperbound_cleanup_size,
+              arena.SpaceAllocated());
   }
 
-  // Now, outside the scope of the NoHeapChecker, test ExtractSubrange's copying
-  // semantics.
+  // Now test ExtractSubrange's copying semantics.
   {
     RepeatedPtrField<TestAllTypes> repeated_message(&arena);
     for (int i = 0; i < 100; i++) {
@@ -1577,8 +1582,11 @@ TEST(ArenaTest, NoHeapAllocationsTest) {
   Arena arena(options);
 
   {
-
+    // We need to call Arena::Create before NoHeapChecker because the ArenaDtor
+    // allocates a new cleanup chunk.
     TestAllTypes* message = Arena::Create<TestAllTypes>(&arena);
+
+
     FillArenaAwareFields(message);
   }
 
@@ -1610,8 +1618,9 @@ TEST(ArenaTest, MessageLiteOnArena) {
   initial_message.SerializeToString(&serialized);
 
   {
-
     MessageLite* generic_message = prototype->New(&arena);
+
+
     EXPECT_TRUE(generic_message != nullptr);
     EXPECT_EQ(&arena, generic_message->GetArena());
     EXPECT_TRUE(generic_message->ParseFromString(serialized));
@@ -1679,6 +1688,23 @@ TEST(ArenaTest, FirstArenaOverhead) {
 }
 
 
+TEST(ArenaTest, StartingBlockSize) {
+  Arena default_arena;
+  EXPECT_EQ(0, default_arena.SpaceAllocated());
+
+  // Allocate something to get starting block size.
+  Arena::CreateArray<char>(&default_arena, 1);
+  ArenaOptions options;
+  // First block size should be the default starting block size.
+  EXPECT_EQ(default_arena.SpaceAllocated(), options.start_block_size);
+
+  // Use a custom starting block size.
+  options.start_block_size *= 2;
+  Arena custom_arena(options);
+  Arena::CreateArray<char>(&custom_arena, 1);
+  EXPECT_EQ(custom_arena.SpaceAllocated(), options.start_block_size);
+}
+
 TEST(ArenaTest, BlockSizeDoubling) {
   Arena arena;
   EXPECT_EQ(0, arena.SpaceUsed());
diff --git a/src/google/protobuf/compiler/command_line_interface.h b/src/google/protobuf/compiler/command_line_interface.h
index 43ab8eee1d..9dec6c998d 100644
--- a/src/google/protobuf/compiler/command_line_interface.h
+++ b/src/google/protobuf/compiler/command_line_interface.h
@@ -469,7 +469,8 @@ class PROTOC_EXPORT CommandLineInterface {
   // When using --encode, this will be passed to SetSerializationDeterministic.
   bool deterministic_output_ = false;
 
-  bool opensource_runtime_ = PROTO2_IS_OSS;
+  bool opensource_runtime_ = google::protobuf::internal::IsOss();
+
 };
 
 }  // namespace compiler
diff --git a/src/google/protobuf/compiler/cpp/field_generators/enum_field.cc b/src/google/protobuf/compiler/cpp/field_generators/enum_field.cc
index 529014ea89..9e83ad2f50 100644
--- a/src/google/protobuf/compiler/cpp/field_generators/enum_field.cc
+++ b/src/google/protobuf/compiler/cpp/field_generators/enum_field.cc
@@ -544,17 +544,15 @@ void RepeatedEnum::GenerateByteSize(io::Printer* p) const {
            }},
       },
       R"cc(
-        {
-          std::size_t data_size = 0;
-          auto count = static_cast<std::size_t>(this->_internal_$name$_size());
+        std::size_t data_size = 0;
+        auto count = static_cast<std::size_t>(this->_internal_$name$_size());
 
-          for (std::size_t i = 0; i < count; ++i) {
-            data_size += ::_pbi::WireFormatLite::EnumSize(
-                this->_internal_$name$().Get(static_cast<int>(i)));
-          }
-          total_size += data_size;
-          $add_to_size$;
+        for (std::size_t i = 0; i < count; ++i) {
+          data_size += ::_pbi::WireFormatLite::EnumSize(
+              this->_internal_$name$().Get(static_cast<int>(i)));
         }
+        total_size += data_size;
+        $add_to_size$;
       )cc");
 }
 }  // namespace
diff --git a/src/google/protobuf/compiler/cpp/field_generators/primitive_field.cc b/src/google/protobuf/compiler/cpp/field_generators/primitive_field.cc
index 607fe10aad..22279db2bf 100644
--- a/src/google/protobuf/compiler/cpp/field_generators/primitive_field.cc
+++ b/src/google/protobuf/compiler/cpp/field_generators/primitive_field.cc
@@ -635,12 +635,10 @@ void RepeatedPrimitive::GenerateByteSize(io::Printer* p) const {
               .WithSuffix(""),
       },
       R"cc(
-        {
-          std::size_t data_size = $data_size$;
-          $maybe_cache_data_size$;
-          std::size_t tag_size = $tag_size$;
-          total_size += tag_size + data_size;
-        }
+        std::size_t data_size = $data_size$;
+        $maybe_cache_data_size$;
+        std::size_t tag_size = $tag_size$;
+        total_size += tag_size + data_size;
       )cc");
 }
 }  // namespace
diff --git a/src/google/protobuf/compiler/cpp/generator.h b/src/google/protobuf/compiler/cpp/generator.h
index 20d037e843..c200b51078 100644
--- a/src/google/protobuf/compiler/cpp/generator.h
+++ b/src/google/protobuf/compiler/cpp/generator.h
@@ -24,6 +24,7 @@
 #include "google/protobuf/compiler/code_generator.h"
 #include "google/protobuf/cpp_features.pb.h"
 #include "google/protobuf/descriptor.pb.h"
+#include "google/protobuf/port.h"
 
 // Must be included last.
 #include "google/protobuf/port_def.inc"
@@ -85,7 +86,7 @@ class PROTOC_EXPORT CppGenerator : public CodeGenerator {
   using CodeGenerator::GetResolvedSourceFeatures;
 
  private:
-  bool opensource_runtime_ = PROTO2_IS_OSS;
+  bool opensource_runtime_ = google::protobuf::internal::IsOss();
   std::string runtime_include_base_;
 
   absl::Status ValidateFeatures(const FileDescriptor* file) const;
diff --git a/src/google/protobuf/compiler/cpp/message.cc b/src/google/protobuf/compiler/cpp/message.cc
index 647f804d20..e9e0ae2e37 100644
--- a/src/google/protobuf/compiler/cpp/message.cc
+++ b/src/google/protobuf/compiler/cpp/message.cc
@@ -183,60 +183,55 @@ RunMap FindRuns(const std::vector<const FieldDescriptor*>& fields,
   return runs;
 }
 
-// Emits an if-statement with a condition that evaluates to true if |field| is
-// considered non-default (will be sent over the wire), for message types
-// without true field presence. Should only be called if
-// !HasHasbit(field).
-bool EmitFieldNonDefaultCondition(io::Printer* p, const std::string& prefix,
-                                  const FieldDescriptor* field) {
+void EmitNonDefaultCheck(io::Printer* p, const std::string& prefix,
+                         const FieldDescriptor* field) {
   ABSL_CHECK(!HasHasbit(field));
+  ABSL_CHECK(!field->is_repeated());
+  ABSL_CHECK(!field->containing_oneof() || field->real_containing_oneof());
+
   auto v = p->WithVars({{
       {"prefix", prefix},
       {"name", FieldName(field)},
   }});
   // Merge and serialize semantics: primitive fields are merged/serialized only
   // if non-zero (numeric) or non-empty (string).
-  if (!field->is_repeated() && !field->containing_oneof()) {
+  if (!field->containing_oneof()) {
     if (field->cpp_type() == FieldDescriptor::CPPTYPE_STRING) {
-      p->Emit(R"cc(
-        if (!$prefix$_internal_$name$().empty()) {
-      )cc");
+      p->Emit("!$prefix$_internal_$name$().empty()");
     } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_MESSAGE) {
       // Message fields still have has_$name$() methods.
-      p->Emit(R"cc(
-        if ($prefix$_internal_has_$name$()) {
-      )cc");
+      p->Emit("$prefix$_internal_has_$name$()");
     } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_FLOAT) {
-      p->Emit(R"cc(
-        static_assert(sizeof(::uint32_t) == sizeof(float),
-                      "Code assumes ::uint32_t and float are the same size.");
-        float tmp_$name$ = $prefix$_internal_$name$();
-        ::uint32_t raw_$name$;
-        memcpy(&raw_$name$, &tmp_$name$, sizeof(tmp_$name$));
-        if (raw_$name$ != 0) {
-      )cc");
+      p->Emit("::absl::bit_cast<::uint32_t>($prefix$_internal_$name$()) != 0");
     } else if (field->cpp_type() == FieldDescriptor::CPPTYPE_DOUBLE) {
-      p->Emit(R"cc(
-        static_assert(sizeof(::uint64_t) == sizeof(double),
-                      "Code assumes ::uint64_t and double are the same size.");
-        double tmp_$name$ = $prefix$_internal_$name$();
-        ::uint64_t raw_$name$;
-        memcpy(&raw_$name$, &tmp_$name$, sizeof(tmp_$name$));
-        if (raw_$name$ != 0) {
-      )cc");
+      p->Emit("::absl::bit_cast<::uint64_t>($prefix$_internal_$name$()) != 0");
     } else {
-      p->Emit(R"cc(
-        if ($prefix$_internal_$name$() != 0) {
-      )cc");
+      p->Emit("$prefix$_internal_$name$() != 0");
     }
-    return true;
   } else if (field->real_containing_oneof()) {
-    p->Emit(R"cc(
-      if ($has_field$) {
-    )cc");
-    return true;
+    p->Emit("$has_field$");
   }
-  return false;
+}
+
+bool ShouldEmitNonDefaultCheck(const FieldDescriptor* field) {
+  return (!field->is_repeated() && !field->containing_oneof()) ||
+         field->real_containing_oneof();
+}
+
+// Emits an if-statement with a condition that evaluates to true if |field| is
+// considered non-default (will be sent over the wire), for message types
+// without true field presence. Should only be called if
+// !HasHasbit(field).
+bool MayEmitIfNonDefaultCheck(io::Printer* p, const std::string& prefix,
+                              const FieldDescriptor* field) {
+  ABSL_CHECK(!HasHasbit(field));
+  if (!ShouldEmitNonDefaultCheck(field)) return false;
+
+  p->Emit({{"condition", [&] { EmitNonDefaultCheck(p, prefix, field); }}},
+          R"cc(
+            if ($condition$) {
+          )cc");
+  return true;
 }
 
 bool HasInternalHasMethod(const FieldDescriptor* field) {
@@ -3752,8 +3747,7 @@ void MessageGenerator::GenerateMergeFrom(io::Printer* p) {
     format(
         "void $classname$::CheckTypeAndMergeFrom(\n"
         "    const ::$proto_ns$::MessageLite& from) {\n"
-        "  MergeFrom(*::_pbi::DownCast<const $classname$*>(\n"
-        "      &from));\n"
+        "  MergeFrom(::$proto_ns$::DownCastToGenerated<$classname$>(from));\n"
         "}\n");
   }
 }
@@ -3867,8 +3861,7 @@ void MessageGenerator::GenerateClassSpecificMergeImpl(io::Printer* p) {
         } else if (field->is_optional() && !HasHasbit(field)) {
           // Merge semantics without true field presence: primitive fields are
           // merged only if non-zero (numeric) or non-empty (string).
-          bool have_enclosing_if =
-              EmitFieldNonDefaultCondition(p, "from.", field);
+          bool have_enclosing_if = MayEmitIfNonDefaultCheck(p, "from.", field);
           if (have_enclosing_if) format.Indent();
           generator.GenerateMergingCode(p);
           if (have_enclosing_if) {
@@ -4140,7 +4133,7 @@ void MessageGenerator::GenerateSerializeOneField(io::Printer* p,
           }
         )cc");
   } else if (field->is_optional()) {
-    bool have_enclosing_if = EmitFieldNonDefaultCondition(p, "this->", field);
+    bool have_enclosing_if = MayEmitIfNonDefaultCheck(p, "this->", field);
     if (have_enclosing_if) p->Indent();
     emit_body();
     if (have_enclosing_if) {
@@ -4561,23 +4554,6 @@ void MessageGenerator::GenerateByteSize(io::Printer* p) {
     return;
   }
 
-  Formatter format(p);
-  format(
-      "::size_t $classname$::ByteSizeLong() const {\n"
-      "$WeakDescriptorSelfPin$"
-      "$annotate_bytesize$"
-      "// @@protoc_insertion_point(message_byte_size_start:$full_name$)\n");
-  format.Indent();
-  format(
-      "::size_t total_size = 0;\n"
-      "\n");
-
-  if (descriptor_->extension_range_count() > 0) {
-    format(
-        "total_size += $extensions$.ByteSize();\n"
-        "\n");
-  }
-
   std::vector<FieldChunk> chunks = CollectFields(
       optimized_order_, options_,
       [&](const FieldDescriptor* a, const FieldDescriptor* b) -> bool {
@@ -4586,177 +4562,278 @@ void MessageGenerator::GenerateByteSize(io::Printer* p) {
                ShouldSplit(a, options_) == ShouldSplit(b, options_);
       });
 
-  auto it = chunks.begin();
-  auto end = chunks.end();
-  int cached_has_word_index = -1;
-
-  format(
-      "$uint32$ cached_has_bits = 0;\n"
-      "// Prevent compiler warnings about cached_has_bits being unused\n"
-      "(void) cached_has_bits;\n\n");
-
-  // See comment in third_party/protobuf/port.h for details,
-  // on how much we are prefetching. Only insert prefetch once per
-  // function, since advancing is actually slower. We sometimes
-  // prefetch more than sizeof(message), because it helps with
-  // next message on arena.
-  bool generate_prefetch = false;
-  // Skip trivial messages with 0 or 1 fields, unless they are repeated,
-  // to reduce codesize.
-  switch (optimized_order_.size()) {
-    case 1:
-      generate_prefetch = optimized_order_[0]->is_repeated();
-      break;
-    case 0:
-      break;
-    default:
-      generate_prefetch = true;
-  }
-  if (!IsPresentMessage(descriptor_, options_)) {
-    generate_prefetch = false;
-  }
-  if (generate_prefetch) {
-    p->Emit(R"cc(
-      ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-    )cc");
-  }
-
-  while (it != end) {
-    auto next = FindNextUnequalChunk(it, end, MayGroupChunksForHaswordsCheck);
-    bool has_haswords_check = MaybeEmitHaswordsCheck(
-        it, next, options_, has_bit_indices_, cached_has_word_index, "", p);
-
-    while (it != next) {
-      const std::vector<const FieldDescriptor*>& fields = it->fields;
-      const bool check_has_byte = fields.size() > 1 &&
-                                  HasWordIndex(fields[0]) != kNoHasbit &&
-                                  !IsLikelyPresent(fields.back(), options_);
-
-      if (check_has_byte) {
-        // Emit an if() that will let us skip the whole chunk if none are set.
-        uint32_t chunk_mask = GenChunkMask(fields, has_bit_indices_);
-        std::string chunk_mask_str =
-            absl::StrCat(absl::Hex(chunk_mask, absl::kZeroPad8));
-
-        // Check (up to) 8 has_bits at a time if we have more than one field in
-        // this chunk.  Due to field layout ordering, we may check
-        // _has_bits_[last_chunk * 8 / 32] multiple times.
-        ABSL_DCHECK_LE(2, popcnt(chunk_mask));
-        ABSL_DCHECK_GE(8, popcnt(chunk_mask));
-
-        if (cached_has_word_index != HasWordIndex(fields.front())) {
-          cached_has_word_index = HasWordIndex(fields.front());
-          format("cached_has_bits = $has_bits$[$1$];\n", cached_has_word_index);
-        }
-        format("if (cached_has_bits & 0x$1$u) {\n", chunk_mask_str);
-        format.Indent();
-      }
-
-      // Go back and emit checks for each of the fields we processed.
-      for (const auto* field : fields) {
-        bool have_enclosing_if = false;
-
-        PrintFieldComment(format, field, options_);
-
-        if (field->is_repeated()) {
-          // No presence check is required.
-        } else if (HasHasbit(field)) {
-          PrintPresenceCheck(field, has_bit_indices_, p,
-                             &cached_has_word_index);
-          have_enclosing_if = true;
-        } else {
-          // Without field presence: field is serialized only if it has a
-          // non-default value.
-          have_enclosing_if = EmitFieldNonDefaultCondition(p, "this->", field);
-        }
+  p->Emit(
+      {{"handle_extension_set",
+        [&] {
+          if (descriptor_->extension_range_count() == 0) return;
+          p->Emit(R"cc(
+            total_size += $extensions$.ByteSize();
+          )cc");
+        }},
+       {"prefetch",
+        [&] {
+          // See comment in third_party/protobuf/port.h for details,
+          // on how much we are prefetching. Only insert prefetch once per
+          // function, since advancing is actually slower. We sometimes
+          // prefetch more than sizeof(message), because it helps with
+          // next message on arena.
+          bool generate_prefetch = false;
+          // Skip trivial messages with 0 or 1 fields, unless they are
+          // repeated, to reduce codesize.
+          switch (optimized_order_.size()) {
+            case 1:
+              generate_prefetch = optimized_order_[0]->is_repeated();
+              break;
+            case 0:
+              break;
+            default:
+              generate_prefetch = true;
+          }
+          if (!generate_prefetch || !IsPresentMessage(descriptor_, options_)) {
+            return;
+          }
+          p->Emit(R"cc(
+            ::_pbi::Prefetch5LinesFrom7Lines(
+                reinterpret_cast<const void*>(this));
+          )cc");
+        }},
+       {"handle_fields",
+        [&] {
+          auto it = chunks.begin();
+          auto end = chunks.end();
+          int cached_has_word_index = -1;
+
+          while (it != end) {
+            auto next =
+                FindNextUnequalChunk(it, end, MayGroupChunksForHaswordsCheck);
+            bool has_haswords_check =
+                MaybeEmitHaswordsCheck(it, next, options_, has_bit_indices_,
+                                       cached_has_word_index, "", p);
+
+            while (it != next) {
+              const auto& fields = it->fields;
+              const bool check_has_byte =
+                  fields.size() > 1 && HasWordIndex(fields[0]) != kNoHasbit &&
+                  !IsLikelyPresent(fields.back(), options_);
+              p->Emit(
+                  {{"update_byte_size_for_chunk",
+                    [&] {
+                      // Go back and emit checks for each of the fields we
+                      // processed.
+                      for (const auto* field : fields) {
+                        p->Emit(
+                            {{"comment",
+                              [&] {
+                                PrintFieldComment(Formatter{p}, field,
+                                                  options_);
+                              }},
+                             {"update_byte_size_for_field",
+                              [&] {
+                                field_generators_.get(field).GenerateByteSize(
+                                    p);
+                              }},
+                             {"update_cached_has_bits",
+                              [&] {
+                                if (!HasHasbit(field) ||
+                                    field->options().weak())
+                                  return;
+                                int has_bit_index =
+                                    has_bit_indices_[field->index()];
+                                if (cached_has_word_index ==
+                                    (has_bit_index / 32))
+                                  return;
+                                cached_has_word_index = (has_bit_index / 32);
+                                p->Emit({{"index", cached_has_word_index}},
+                                        R"cc(
+                                          cached_has_bits = $has_bits$[$index$];
+                                        )cc");
+                              }},
+                             {"check_if_field_present",
+                              [&] {
+                                if (HasHasbit(field)) {
+                                  if (field->options().weak()) {
+                                    p->Emit("if (has_$name$())");
+                                    return;
+                                  }
+
+                                  int has_bit_index =
+                                      has_bit_indices_[field->index()];
+                                  p->Emit({{"mask",
+                                            absl::StrFormat(
+                                                "0x%08xu",
+                                                1u << (has_bit_index % 32))}},
+                                          "if (cached_has_bits & $mask$)");
+                                } else if (ShouldEmitNonDefaultCheck(field)) {
+                                  // Without field presence: field is
+                                  // serialized only if it has a non-default
+                                  // value.
+                                  p->Emit({{"non_default_check",
+                                            [&] {
+                                              EmitNonDefaultCheck(p, "this->",
+                                                                  field);
+                                            }}},
+                                          "if ($non_default_check$)");
+                                }
+                              }}},
+                            R"cc(
+                              $comment$;
+                              $update_cached_has_bits$;
+                              $check_if_field_present$ {
+                                //~ Force newline.
+                                $update_byte_size_for_field$;
+                              }
+                            )cc");
+                      }
+                    }},
+                   {"may_update_cached_has_word_index",
+                    [&] {
+                      if (!check_has_byte) return;
+                      if (cached_has_word_index == HasWordIndex(fields.front()))
+                        return;
+
+                      cached_has_word_index = HasWordIndex(fields.front());
+                      p->Emit({{"index", cached_has_word_index}},
+                              R"cc(
+                                cached_has_bits = $has_bits$[$index$];
+                              )cc");
+                    }},
+                   {"check_if_chunk_present",
+                    [&] {
+                      if (!check_has_byte) {
+                        return;
+                      }
 
-        if (have_enclosing_if) format.Indent();
+                      // Emit an if() that will let us skip the whole chunk
+                      // if none are set.
+                      uint32_t chunk_mask =
+                          GenChunkMask(fields, has_bit_indices_);
 
-        field_generators_.get(field).GenerateByteSize(p);
+                      // Check (up to) 8 has_bits at a time if we have more
+                      // than one field in this chunk.  Due to field layout
+                      // ordering, we may check _has_bits_[last_chunk * 8 /
+                      // 32] multiple times.
+                      ABSL_DCHECK_LE(2, popcnt(chunk_mask));
+                      ABSL_DCHECK_GE(8, popcnt(chunk_mask));
 
-        if (have_enclosing_if) {
-          format.Outdent();
-          format(
-              "}\n"
-              "\n");
-        }
-      }
+                      p->Emit(
+                          {{"mask", absl::StrFormat("0x%08xu", chunk_mask)}},
+                          "if (cached_has_bits & $mask$)");
+                    }}},
+                  R"cc(
+                    $may_update_cached_has_word_index$;
+                    $check_if_chunk_present$ {
+                      //~ Force newline.
+                      $update_byte_size_for_chunk$;
+                    }
+                  )cc");
 
-      if (check_has_byte) {
-        format.Outdent();
-        format("}\n");
-      }
+              // To next chunk.
+              ++it;
+            }
 
-      // To next chunk.
-      ++it;
-    }
+            if (has_haswords_check) {
+              p->Emit(R"cc(
+                }
+              )cc");
 
-    if (has_haswords_check) {
-      p->Outdent();
-      p->Emit(R"cc(
+              // Reset here as it may have been updated in just closed if
+              // statement.
+              cached_has_word_index = -1;
+            }
+          }
+        }},
+       {"handle_oneof_fields",
+        [&] {
+          // Fields inside a oneof don't use _has_bits_ so we count them in a
+          // separate pass.
+          for (auto oneof : OneOfRange(descriptor_)) {
+            p->Emit(
+                {{"oneof_name", oneof->name()},
+                 {"oneof_case_name", absl::AsciiStrToUpper(oneof->name())},
+                 {"case_per_field",
+                  [&] {
+                    for (auto field : FieldRange(oneof)) {
+                      PrintFieldComment(Formatter{p}, field, options_);
+                      p->Emit(
+                          {{"field_name",
+                            UnderscoresToCamelCase(field->name(), true)},
+                           {"field_byte_size",
+                            [&] {
+                              field_generators_.get(field).GenerateByteSize(p);
+                            }}},
+                          R"cc(
+                            case k$field_name$: {
+                              $field_byte_size$;
+                              break;
+                            }
+                          )cc");
+                    }
+                  }}},
+                R"cc(
+                  switch ($oneof_name$_case()) {
+                    $case_per_field$;
+                    case $oneof_case_name$_NOT_SET: {
+                      break;
+                    }
+                  }
+                )cc");
+          }
+        }},
+       {"handle_weak_fields",
+        [&] {
+          if (num_weak_fields_ == 0) return;
+          // TagSize + MessageSize
+          p->Emit(R"cc(
+            total_size += $weak_field_map$.ByteSizeLong();
+          )cc");
+        }},
+       {"handle_unknown_fields",
+        [&] {
+          if (UseUnknownFieldSet(descriptor_->file(), options_)) {
+            // We go out of our way to put the computation of the uncommon
+            // path of unknown fields in tail position. This allows for
+            // better code generation of this function for simple protos.
+            p->Emit(R"cc(
+              return MaybeComputeUnknownFieldsSize(total_size, &$cached_size$);
+            )cc");
+          } else {
+            // We update _cached_size_ even though this is a const method.
+            // Because const methods might be called concurrently this needs
+            // to be atomic operations or the program is undefined.  In
+            // practice, since any concurrent writes will be writing the
+            // exact same value, normal writes will work on all common
+            // processors. We use a dedicated wrapper class to abstract away
+            // the underlying atomic. This makes it easier on platforms where
+            // even relaxed memory order might have perf impact to replace it
+            // with ordinary loads and stores.
+            p->Emit(R"cc(
+              if (PROTOBUF_PREDICT_FALSE($have_unknown_fields$)) {
+                total_size += $unknown_fields$.size();
+              }
+              $cached_size$.Set(::_pbi::ToCachedSize(total_size));
+              return total_size;
+            )cc");
+          }
+        }}},
+      R"cc(
+        ::size_t $classname$::ByteSizeLong() const {
+          $WeakDescriptorSelfPin$;
+          $annotate_bytesize$;
+          // @@protoc_insertion_point(message_byte_size_start:$full_name$)
+          ::size_t total_size = 0;
+          $handle_extension_set$;
+
+          $uint32$ cached_has_bits = 0;
+          // Prevent compiler warnings about cached_has_bits being unused
+          (void)cached_has_bits;
+
+          $prefetch$;
+          $handle_fields$;
+          $handle_oneof_fields$;
+          $handle_weak_fields$;
+          $handle_unknown_fields$;
         }
       )cc");
-
-      // Reset here as it may have been updated in just closed if statement.
-      cached_has_word_index = -1;
-    }
-  }
-
-  // Fields inside a oneof don't use _has_bits_ so we count them in a separate
-  // pass.
-  for (auto oneof : OneOfRange(descriptor_)) {
-    format("switch ($1$_case()) {\n", oneof->name());
-    format.Indent();
-    for (auto field : FieldRange(oneof)) {
-      PrintFieldComment(format, field, options_);
-      format("case k$1$: {\n", UnderscoresToCamelCase(field->name(), true));
-      format.Indent();
-      field_generators_.get(field).GenerateByteSize(p);
-      format("break;\n");
-      format.Outdent();
-      format("}\n");
-    }
-    format(
-        "case $1$_NOT_SET: {\n"
-        "  break;\n"
-        "}\n",
-        absl::AsciiStrToUpper(oneof->name()));
-    format.Outdent();
-    format("}\n");
-  }
-
-  if (num_weak_fields_) {
-    // TagSize + MessageSize
-    format("total_size += $weak_field_map$.ByteSizeLong();\n");
-  }
-
-  if (UseUnknownFieldSet(descriptor_->file(), options_)) {
-    // We go out of our way to put the computation of the uncommon path of
-    // unknown fields in tail position. This allows for better code generation
-    // of this function for simple protos.
-    format(
-        "return MaybeComputeUnknownFieldsSize(total_size, &$cached_size$);\n");
-  } else {
-    format("if (PROTOBUF_PREDICT_FALSE($have_unknown_fields$)) {\n");
-    format("  total_size += $unknown_fields$.size();\n");
-    format("}\n");
-
-    // We update _cached_size_ even though this is a const method.  Because
-    // const methods might be called concurrently this needs to be atomic
-    // operations or the program is undefined.  In practice, since any
-    // concurrent writes will be writing the exact same value, normal writes
-    // will work on all common processors. We use a dedicated wrapper class to
-    // abstract away the underlying atomic. This makes it easier on platforms
-    // where even relaxed memory order might have perf impact to replace it with
-    // ordinary loads and stores.
-    p->Emit(R"cc(
-      $cached_size$.Set(::_pbi::ToCachedSize(total_size));
-      return total_size;
-    )cc");
-  }
-
-  format.Outdent();
-  format("}\n");
 }
 
 bool MessageGenerator::NeedsIsInitialized() {
diff --git a/src/google/protobuf/compiler/cpp/service.cc b/src/google/protobuf/compiler/cpp/service.cc
index 88527c119e..9da41c198a 100644
--- a/src/google/protobuf/compiler/cpp/service.cc
+++ b/src/google/protobuf/compiler/cpp/service.cc
@@ -256,8 +256,8 @@ void ServiceGenerator::GenerateCallMethodCases(io::Printer* printer) {
         R"cc(
           case $index$:
             $name$(controller,
-                   ::$proto_ns$::internal::DownCast<const $input$*>(request),
-                   ::$proto_ns$::internal::DownCast<$output$*>(response), done);
+                   ::$proto_ns$::DownCastToGenerated<$input$>(request),
+                   ::$proto_ns$::DownCastToGenerated<$output$>(response), done);
             break;
         )cc");
   }
diff --git a/src/google/protobuf/compiler/cpp/unittest.inc b/src/google/protobuf/compiler/cpp/unittest.inc
index c4b27ae94a..6c1fe420e0 100644
--- a/src/google/protobuf/compiler/cpp/unittest.inc
+++ b/src/google/protobuf/compiler/cpp/unittest.inc
@@ -1022,8 +1022,8 @@ TEST(GENERATED_ENUM_TEST_NAME, MinAndMax) {
   EXPECT_EQ(4, UNITTEST::TestAllTypes::NestedEnum_ARRAYSIZE);
 
   EXPECT_EQ(UNITTEST::FOREIGN_FOO, UNITTEST::ForeignEnum_MIN);
-  EXPECT_EQ(UNITTEST::FOREIGN_BAX, UNITTEST::ForeignEnum_MAX);
-  EXPECT_EQ(33, UNITTEST::ForeignEnum_ARRAYSIZE);
+  EXPECT_EQ(UNITTEST::FOREIGN_LARGE, UNITTEST::ForeignEnum_MAX);
+  EXPECT_EQ(123457, UNITTEST::ForeignEnum_ARRAYSIZE);
 
   EXPECT_EQ(1, UNITTEST::TestEnumWithDupValue_MIN);
   EXPECT_EQ(3, UNITTEST::TestEnumWithDupValue_MAX);
@@ -1314,13 +1314,13 @@ TEST_F(GENERATED_SERVICE_TEST_NAME, CallMethodTypeFailure) {
   EXPECT_DEBUG_DEATH(
     mock_service_.CallMethod(foo_, &mock_controller_,
                              &foo_request_, &bar_response_, done_.get()),
-    "dynamic_cast");
+    "DynamicCastToGenerated");
 
   mock_service_.Reset();
   EXPECT_DEBUG_DEATH(
     mock_service_.CallMethod(foo_, &mock_controller_,
                              &bar_request_, &foo_response_, done_.get()),
-    "dynamic_cast");
+    "DynamicCastToGenerated");
 #endif  // GTEST_HAS_DEATH_TEST
 }
 
diff --git a/src/google/protobuf/compiler/java/BUILD.bazel b/src/google/protobuf/compiler/java/BUILD.bazel
index 39f862f6cc..40cd4a5fd8 100644
--- a/src/google/protobuf/compiler/java/BUILD.bazel
+++ b/src/google/protobuf/compiler/java/BUILD.bazel
@@ -35,7 +35,6 @@ cc_library(
     hdrs = [
         "context.h",
         "doc_comment.h",
-        "generator.h",
         "helpers.h",
         "name_resolver.h",
         "names.h",
@@ -48,7 +47,6 @@ cc_library(
         "//src/google/protobuf/compiler/java:__subpackages__",
     ],
     deps = [
-        ":java_features_bootstrap",
         "//src/google/protobuf",
         "//src/google/protobuf:port",
         "//src/google/protobuf/compiler:code_generator",
@@ -64,6 +62,25 @@ cc_library(
     ],
 )
 
+cc_library(
+    name = "internal_helpers",
+    srcs = ["internal_helpers.cc"],
+    hdrs = [
+        "generator.h",
+        "internal_helpers.h",
+    ],
+    strip_include_prefix = "/src",
+    visibility = ["//src/google/protobuf/compiler/java:__subpackages__"],
+    deps = [
+        ":helpers",
+        ":java_features_bootstrap",
+        "//src/google/protobuf",
+        "//src/google/protobuf:port",
+        "//src/google/protobuf/compiler:code_generator",
+        "@com_google_absl//absl/log:absl_log",
+    ],
+)
+
 cc_library(
     name = "java_features_bootstrap",
     srcs = ["java_features.pb.cc"],
@@ -111,7 +128,7 @@ cc_library(
         "//src/google/protobuf/compiler:code_generator",
         "//src/google/protobuf/compiler:retention",
         "//src/google/protobuf/compiler:versions",
-        "//src/google/protobuf/compiler/java/immutable",
+        "//src/google/protobuf/compiler/java/full",
         "//src/google/protobuf/compiler/java/lite",
         "//src/google/protobuf/io",
         "//src/google/protobuf/io:printer",
@@ -144,6 +161,7 @@ cc_library(
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/log:absl_check",
         "@com_google_absl//absl/log:absl_log",
+        "@com_google_absl//absl/strings",
         "@com_google_absl//absl/strings:string_view",
     ],
 )
diff --git a/src/google/protobuf/compiler/java/field_common.cc b/src/google/protobuf/compiler/java/field_common.cc
index 4acafabe36..cf5cdcbf0a 100644
--- a/src/google/protobuf/compiler/java/field_common.cc
+++ b/src/google/protobuf/compiler/java/field_common.cc
@@ -1,8 +1,11 @@
 #include "google/protobuf/compiler/java/field_common.h"
 
+#include <cstddef>
 #include <string>
 
+#include "absl/strings/str_cat.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/names.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
@@ -10,6 +13,8 @@ namespace protobuf {
 namespace compiler {
 namespace java {
 
+std::string GetKotlinPropertyName(std::string capitalized_name);
+
 void SetCommonFieldVariables(
     const FieldDescriptor* descriptor, const FieldGeneratorInfo* info,
     absl::flat_hash_map<absl::string_view, std::string>* variables) {
@@ -30,6 +35,11 @@ void SetCommonFieldVariables(
   (*variables)["kt_name"] = IsForbiddenKotlin(info->name)
                                 ? absl::StrCat(info->name, "_")
                                 : info->name;
+  auto kt_property_name = GetKotlinPropertyName(info->capitalized_name);
+  (*variables)["kt_property_name"] = kt_property_name;
+  (*variables)["kt_safe_name"] = IsForbiddenKotlin(kt_property_name)
+                                     ? absl::StrCat("`", kt_property_name, "`")
+                                     : kt_property_name;
   (*variables)["kt_capitalized_name"] =
       IsForbiddenKotlin(info->name) ? absl::StrCat(info->capitalized_name, "_")
                                     : info->capitalized_name;
@@ -51,6 +61,51 @@ void SetCommonFieldVariables(
   }
 }
 
+// Locale-independent ASCII upper and lower case munging.
+static bool IsUpper(char c) {
+  return static_cast<unsigned int>(c - 'A') <= 'Z' - 'A';
+}
+
+static char ToLower(char c) { return IsUpper(c) ? c - 'A' + 'a' : c; }
+
+// Returns the name by which the generated Java getters and setters should be
+// referenced from Kotlin as properties. In the simplest case, the original name
+// is something like `foo_bar`, which gets translated into `getFooBar()` etc,
+// and that in turn can be referenced from Kotlin as `fooBar`.
+//
+// The algorithm for translating proto names into Java getters and setters is
+// straightforward. The first letter of each underscore-separated word gets
+// uppercased and the underscores are deleted. There are no other changes, so in
+// particular if the proto name has a string of capitals then those remain
+// as-is.
+//
+// The algorithm that the Kotlin compiler uses to derive the property name is
+// slightly more complicated. If the first character after `get` (etc) is a
+// capital and the second isn't, then the property name is just that string with
+// its first letter lowercased. So `getFoo` becomes `foo` and `getX` becomes
+// `x`. But if there is more than one capital, then all but the last get
+// lowercased. So `getHTMLPage` becomes `htmlPage`. If there are only capitals
+// then they all get lowercased, so `getID` becomes `id`.
+// TODO: move this to a Kotlin-specific location
+std::string GetKotlinPropertyName(std::string capitalized_name) {
+  // Find the first non-capital. If it is the second character, then we just
+  // need to lowercase the first one. Otherwise we need to lowercase everything
+  // up to but not including the last capital, except that if everything is
+  // capitals then everything must be lowercased.
+  std::string kt_property_name = capitalized_name;
+  size_t first_non_capital;
+  for (first_non_capital = 0; first_non_capital < capitalized_name.length() &&
+                              IsUpper(capitalized_name[first_non_capital]);
+       first_non_capital++) {
+  }
+  size_t stop = first_non_capital;
+  if (stop > 1 && stop < capitalized_name.length()) stop--;
+  for (size_t i = 0; i < stop; i++) {
+    kt_property_name[i] = ToLower(kt_property_name[i]);
+  }
+  return kt_property_name;
+}
+
 void SetCommonOneofVariables(
     const FieldDescriptor* descriptor, const OneofGeneratorInfo* info,
     absl::flat_hash_map<absl::string_view, std::string>* variables) {
diff --git a/src/google/protobuf/compiler/java/file.cc b/src/google/protobuf/compiler/java/file.cc
index 2ce6e8978e..6995513bd1 100644
--- a/src/google/protobuf/compiler/java/file.cc
+++ b/src/google/protobuf/compiler/java/file.cc
@@ -25,7 +25,7 @@
 #include "google/protobuf/compiler/java/generator_common.h"
 #include "google/protobuf/compiler/java/generator_factory.h"
 #include "google/protobuf/compiler/java/helpers.h"
-#include "google/protobuf/compiler/java/immutable/generator_factory.h"
+#include "google/protobuf/compiler/java/full/generator_factory.h"
 #include "google/protobuf/compiler/java/lite/generator_factory.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/compiler/java/options.h"
diff --git a/src/google/protobuf/compiler/java/immutable/BUILD.bazel b/src/google/protobuf/compiler/java/full/BUILD.bazel
similarity index 93%
rename from src/google/protobuf/compiler/java/immutable/BUILD.bazel
rename to src/google/protobuf/compiler/java/full/BUILD.bazel
index a65a03acbd..1a7f874326 100644
--- a/src/google/protobuf/compiler/java/immutable/BUILD.bazel
+++ b/src/google/protobuf/compiler/java/full/BUILD.bazel
@@ -35,6 +35,7 @@ cc_library(
         "//src/google/protobuf:port",
         "//src/google/protobuf/compiler/java:generator_common",
         "//src/google/protobuf/compiler/java:helpers",
+        "//src/google/protobuf/compiler/java:internal_helpers",
         "//src/google/protobuf/io:printer",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/log:absl_check",
@@ -45,8 +46,8 @@ cc_library(
 
 cc_library(
     name = "mfg",
-    srcs = ["make_field_generators.cc"],
-    hdrs = ["make_field_generators.h"],
+    srcs = ["make_field_gens.cc"],
+    hdrs = ["make_field_gens.h"],
     strip_include_prefix = "/src",
     deps = [
         ":fg",
@@ -84,14 +85,16 @@ cc_library(
         "//src/google/protobuf:port",
         "//src/google/protobuf/compiler/java:generator_common",
         "//src/google/protobuf/compiler/java:helpers",
+        "//src/google/protobuf/compiler/java:internal_helpers",
         "//src/google/protobuf/io:printer",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:str_format",
     ],
 )
 
 cc_library(
-    name = "immutable",
+    name = "full",
     srcs = [
         "extension.cc",
         "generator_factory.cc",
diff --git a/src/google/protobuf/compiler/java/immutable/enum.cc b/src/google/protobuf/compiler/java/full/enum.cc
similarity index 97%
rename from src/google/protobuf/compiler/java/immutable/enum.cc
rename to src/google/protobuf/compiler/java/full/enum.cc
index 61b307914c..c321c08f31 100644
--- a/src/google/protobuf/compiler/java/immutable/enum.cc
+++ b/src/google/protobuf/compiler/java/full/enum.cc
@@ -9,15 +9,22 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/enum.h"
+#include "google/protobuf/compiler/java/full/enum.h"
 
+#include <algorithm>
+#include <cmath>
 #include <string>
+#include <vector>
 
 #include "absl/container/flat_hash_map.h"
 #include "absl/strings/str_cat.h"
+#include "absl/strings/str_format.h"
+#include "absl/strings/str_join.h"
+#include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/java/context.h"
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/io/printer.h"
@@ -30,6 +37,7 @@ namespace protobuf {
 namespace compiler {
 namespace java {
 
+
 EnumNonLiteGenerator::EnumNonLiteGenerator(const EnumDescriptor* descriptor,
                                            bool immutable_api, Context* context)
     : descriptor_(descriptor),
@@ -56,6 +64,7 @@ void EnumNonLiteGenerator::Generate(io::Printer* printer) {
   WriteEnumDocComment(printer, descriptor_, context_->options());
   MaybePrintGeneratedAnnotation(context_, printer, descriptor_, immutable_api_);
 
+
   if (!context_->options().opensource_runtime) {
     printer->Print("@com.google.protobuf.Internal.ProtoNonnullApi\n");
   }
@@ -374,6 +383,7 @@ void EnumNonLiteGenerator::Generate(io::Printer* printer) {
   printer->Print("}\n\n");
 }
 
+
 bool EnumNonLiteGenerator::CanUseEnumValues() {
   if (canonical_values_.size() != descriptor_->value_count()) {
     return false;
diff --git a/src/google/protobuf/compiler/java/immutable/enum.h b/src/google/protobuf/compiler/java/full/enum.h
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/enum.h
rename to src/google/protobuf/compiler/java/full/enum.h
index 18ccc01e95..8528d7f81f 100644
--- a/src/google/protobuf/compiler/java/immutable/enum.h
+++ b/src/google/protobuf/compiler/java/full/enum.h
@@ -71,6 +71,7 @@ class EnumNonLiteGenerator : public EnumGenerator {
   ClassNameResolver* name_resolver_;
 
   bool CanUseEnumValues();
+
 };
 
 }  // namespace java
diff --git a/src/google/protobuf/compiler/java/immutable/enum_field.cc b/src/google/protobuf/compiler/java/full/enum_field.cc
similarity index 93%
rename from src/google/protobuf/compiler/java/immutable/enum_field.cc
rename to src/google/protobuf/compiler/java/full/enum_field.cc
index 2cb734f498..e0ea6eea65 100644
--- a/src/google/protobuf/compiler/java/immutable/enum_field.cc
+++ b/src/google/protobuf/compiler/java/full/enum_field.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/enum_field.h"
+#include "google/protobuf/compiler/java/full/enum_field.h"
 
 #include <cstdint>
 #include <string>
@@ -22,6 +22,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/wire_format.h"
@@ -273,10 +274,10 @@ void ImmutableEnumFieldGenerator::GenerateKotlinDslMembers(
   printer->Print(variables_,
                  "$kt_deprecation$public var $kt_name$: $kt_type$\n"
                  "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
+                 "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
                  "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
                  "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
+                 "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
                  "  }\n");
 
   if (SupportUnknownEnumValue(descriptor_)) {
@@ -284,10 +285,10 @@ void ImmutableEnumFieldGenerator::GenerateKotlinDslMembers(
         variables_,
         "$kt_deprecation$public var $kt_name$Value: kotlin.Int\n"
         "  @JvmName(\"${$get$kt_capitalized_name$Value$}$\")\n"
-        "  get() = $kt_dsl_builder$.${$get$capitalized_name$Value$}$()\n"
+        "  get() = $kt_dsl_builder$.${$$kt_property_name$Value$}$\n"
         "  @JvmName(\"${$set$kt_capitalized_name$Value$}$\")\n"
         "  set(value) {\n"
-        "    $kt_dsl_builder$.${$set$capitalized_name$Value$}$(value)\n"
+        "    $kt_dsl_builder$.${$$kt_property_name$Value$}$ = value\n"
         "  }\n");
   }
 
@@ -686,13 +687,13 @@ void RepeatedImmutableEnumFieldGenerator::GenerateMembers(
   printer->Print(
       variables_,
       "@SuppressWarnings(\"serial\")\n"
-      "private java.util.List<java.lang.Integer> $name$_;\n"
+      "private com.google.protobuf.Internal.IntList $name$_;\n"
       "private static final "
-      "com.google.protobuf.Internal.ListAdapter.Converter<\n"
-      "    java.lang.Integer, $type$> $name$_converter_ =\n"
-      "        new com.google.protobuf.Internal.ListAdapter.Converter<\n"
-      "            java.lang.Integer, $type$>() {\n"
-      "          public $type$ convert(java.lang.Integer from) {\n"
+      "com.google.protobuf.Internal.IntListAdapter.IntConverter<\n"
+      "    $type$> $name$_converter_ =\n"
+      "        new com.google.protobuf.Internal.IntListAdapter.IntConverter<\n"
+      "            $type$>() {\n"
+      "          public $type$ convert(int from) {\n"
       "            $type$ result = $type$.forNumber(from);\n"
       "            return result == null ? $unknown$ : result;\n"
       "          }\n"
@@ -700,14 +701,13 @@ void RepeatedImmutableEnumFieldGenerator::GenerateMembers(
   PrintExtraFieldInfo(variables_, printer);
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_GETTER,
                                context_->options());
-  printer->Print(
-      variables_,
-      "@java.lang.Override\n"
-      "$deprecation$public java.util.List<$type$> "
-      "${$get$capitalized_name$List$}$() {\n"
-      "  return new com.google.protobuf.Internal.ListAdapter<\n"
-      "      java.lang.Integer, $type$>($name$_, $name$_converter_);\n"
-      "}\n");
+  printer->Print(variables_,
+                 "@java.lang.Override\n"
+                 "$deprecation$public java.util.List<$type$> "
+                 "${$get$capitalized_name$List$}$() {\n"
+                 "  return new com.google.protobuf.Internal.IntListAdapter<\n"
+                 "      $type$>($name$_, $name$_converter_);\n"
+                 "}\n");
   printer->Annotate("{", "}", descriptor_);
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_COUNT,
                                context_->options());
@@ -724,7 +724,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateMembers(
       variables_,
       "@java.lang.Override\n"
       "$deprecation$public $type$ ${$get$capitalized_name$$}$(int index) {\n"
-      "  return $name$_converter_.convert($name$_.get(index));\n"
+      "  return $name$_converter_.convert($name$_.getInt(index));\n"
       "}\n");
   printer->Annotate("{", "}", descriptor_);
   if (SupportUnknownEnumValue(descriptor_)) {
@@ -743,7 +743,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateMembers(
                    "@java.lang.Override\n"
                    "$deprecation$public int "
                    "${$get$capitalized_name$Value$}$(int index) {\n"
-                   "  return $name$_.get(index);\n"
+                   "  return $name$_.getInt(index);\n"
                    "}\n");
     printer->Annotate("{", "}", descriptor_);
   }
@@ -759,19 +759,18 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
       variables_,
       // One field is the list and the other field keeps track of whether the
       // list is immutable. If it's immutable, the invariant is that it must
-      // either an instance of Collections.emptyList() or it's an ArrayList
-      // wrapped in a Collections.unmodifiableList() wrapper and nobody else has
-      // a reference to the underlying ArrayList. This invariant allows us to
-      // share instances of lists between protocol buffers avoiding expensive
-      // memory allocations. Note, immutable is a strong guarantee here -- not
-      // just that the list cannot be modified via the reference but that the
-      // list can never be modified.
-      "private java.util.List<java.lang.Integer> $name$_ =\n"
-      "  java.util.Collections.emptyList();\n"
+      // either an instance of emptyIntList() or it's an immutable IntArrayList
+      // and nobody else has a reference to the underlying ArrayList. This
+      // invariant allows us to share instances of lists between protocol
+      // buffers avoiding expensive memory allocations. Note, immutable is a
+      // strong guarantee here -- not just that the list cannot be modified via
+      // the reference but that the list can never be modified.
+      "private com.google.protobuf.Internal.IntList $name$_ =\n"
+      "  emptyIntList();\n"
 
       "private void ensure$capitalized_name$IsMutable() {\n"
       "  if (!$get_mutable_bit_builder$) {\n"
-      "    $name$_ = new java.util.ArrayList<java.lang.Integer>($name$_);\n"
+      "    $name$_ = makeMutableCopy($name$_);\n"
       "    $set_mutable_bit_builder$;\n"
       "  }\n"
       "}\n");
@@ -786,8 +785,8 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
       //   immutable.
       "$deprecation$public java.util.List<$type$> "
       "${$get$capitalized_name$List$}$() {\n"
-      "  return new com.google.protobuf.Internal.ListAdapter<\n"
-      "      java.lang.Integer, $type$>($name$_, $name$_converter_);\n"
+      "  return new com.google.protobuf.Internal.IntListAdapter<\n"
+      "      $type$>($name$_, $name$_converter_);\n"
       "}\n");
   printer->Annotate("{", "}", descriptor_);
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_COUNT,
@@ -803,7 +802,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
   printer->Print(
       variables_,
       "$deprecation$public $type$ ${$get$capitalized_name$$}$(int index) {\n"
-      "  return $name$_converter_.convert($name$_.get(index));\n"
+      "  return $name$_converter_.convert($name$_.getInt(index));\n"
       "}\n");
   printer->Annotate("{", "}", descriptor_);
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_INDEXED_SETTER,
@@ -816,7 +815,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
                  "    throw new NullPointerException();\n"
                  "  }\n"
                  "  ensure$capitalized_name$IsMutable();\n"
-                 "  $name$_.set(index, value.getNumber());\n"
+                 "  $name$_.setInt(index, value.getNumber());\n"
                  "  onChanged();\n"
                  "  return this;\n"
                  "}\n");
@@ -831,7 +830,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
                  "    throw new NullPointerException();\n"
                  "  }\n"
                  "  ensure$capitalized_name$IsMutable();\n"
-                 "  $name$_.add(value.getNumber());\n"
+                 "  $name$_.addInt(value.getNumber());\n"
                  "  onChanged();\n"
                  "  return this;\n"
                  "}\n");
@@ -844,7 +843,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
                  "    java.lang.Iterable<? extends $type$> values) {\n"
                  "  ensure$capitalized_name$IsMutable();\n"
                  "  for ($type$ value : values) {\n"
-                 "    $name$_.add(value.getNumber());\n"
+                 "    $name$_.addInt(value.getNumber());\n"
                  "  }\n"
                  "  onChanged();\n"
                  "  return this;\n"
@@ -856,7 +855,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
   printer->Print(
       variables_,
       "$deprecation$public Builder ${$clear$capitalized_name$$}$() {\n"
-      "  $name$_ = java.util.Collections.emptyList();\n"
+      "  $name$_ = emptyIntList();\n"
       "  $clear_mutable_bit_builder$;\n"
       "  onChanged();\n"
       "  return this;\n"
@@ -877,7 +876,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
     printer->Print(variables_,
                    "$deprecation$public int "
                    "${$get$capitalized_name$Value$}$(int index) {\n"
-                   "  return $name$_.get(index);\n"
+                   "  return $name$_.getInt(index);\n"
                    "}\n");
     printer->Annotate("{", "}", descriptor_);
     WriteFieldEnumValueAccessorDocComment(
@@ -888,7 +887,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
         "$deprecation$public Builder ${$set$capitalized_name$Value$}$(\n"
         "    int index, int value) {\n"
         "  ensure$capitalized_name$IsMutable();\n"
-        "  $name$_.set(index, value);\n"
+        "  $name$_.setInt(index, value);\n"
         "  onChanged();\n"
         "  return this;\n"
         "}\n");
@@ -900,7 +899,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
                    "$deprecation$public Builder "
                    "${$add$capitalized_name$Value$}$(int value) {\n"
                    "  ensure$capitalized_name$IsMutable();\n"
-                   "  $name$_.add(value);\n"
+                   "  $name$_.addInt(value);\n"
                    "  onChanged();\n"
                    "  return this;\n"
                    "}\n");
@@ -914,7 +913,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderMembers(
         "    java.lang.Iterable<java.lang.Integer> values) {\n"
         "  ensure$capitalized_name$IsMutable();\n"
         "  for (int value : values) {\n"
-        "    $name$_.add(value);\n"
+        "    $name$_.addInt(value);\n"
         "  }\n"
         "  onChanged();\n"
         "  return this;\n"
@@ -930,13 +929,13 @@ void RepeatedImmutableEnumFieldGenerator::
 
 void RepeatedImmutableEnumFieldGenerator::GenerateInitializationCode(
     io::Printer* printer) const {
-  printer->Print(variables_, "$name$_ = java.util.Collections.emptyList();\n");
+  printer->Print(variables_, "$name$_ = emptyIntList();\n");
 }
 
 void RepeatedImmutableEnumFieldGenerator::GenerateBuilderClearCode(
     io::Printer* printer) const {
   printer->Print(variables_,
-                 "$name$_ = java.util.Collections.emptyList();\n"
+                 "$name$_ = emptyIntList();\n"
                  "$clear_mutable_bit_builder$;\n");
 }
 
@@ -964,13 +963,12 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuildingCode(
     io::Printer* printer) const {
   // The code below ensures that the result has an immutable list. If our
   // list is immutable, we can just reuse it. If not, we make it immutable.
-  printer->Print(
-      variables_,
-      "if ($get_mutable_bit_builder$) {\n"
-      "  $name$_ = java.util.Collections.unmodifiableList($name$_);\n"
-      "  $clear_mutable_bit_builder$;\n"
-      "}\n"
-      "result.$name$_ = $name$_;\n");
+  printer->Print(variables_,
+                 "if ($get_mutable_bit_builder$) {\n"
+                 "  $name$_.makeImmutable();\n"
+                 "  $clear_mutable_bit_builder$;\n"
+                 "}\n"
+                 "result.$name$_ = $name$_;\n");
 }
 
 void RepeatedImmutableEnumFieldGenerator::GenerateBuilderParsingCode(
@@ -980,7 +978,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderParsingCode(
     printer->Print(variables_,
                    "int tmpRaw = input.readEnum();\n"
                    "ensure$capitalized_name$IsMutable();\n"
-                   "$name$_.add(tmpRaw);\n");
+                   "$name$_.addInt(tmpRaw);\n");
   } else {
     printer->Print(variables_,
                    "int tmpRaw = input.readEnum();\n"
@@ -990,7 +988,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateBuilderParsingCode(
                    "  mergeUnknownVarintField($number$, tmpRaw);\n"
                    "} else {\n"
                    "  ensure$capitalized_name$IsMutable();\n"
-                   "  $name$_.add(tmpRaw);\n"
+                   "  $name$_.addInt(tmpRaw);\n"
                    "}\n");
   }
 }
@@ -1021,12 +1019,12 @@ void RepeatedImmutableEnumFieldGenerator::GenerateSerializationCode(
                    "  output.writeUInt32NoTag($name$MemoizedSerializedSize);\n"
                    "}\n"
                    "for (int i = 0; i < $name$_.size(); i++) {\n"
-                   "  output.writeEnumNoTag($name$_.get(i));\n"
+                   "  output.writeEnumNoTag($name$_.getInt(i));\n"
                    "}\n");
   } else {
     printer->Print(variables_,
                    "for (int i = 0; i < $name$_.size(); i++) {\n"
-                   "  output.writeEnum($number$, $name$_.get(i));\n"
+                   "  output.writeEnum($number$, $name$_.getInt(i));\n"
                    "}\n");
   }
 }
@@ -1041,7 +1039,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateSerializedSizeCode(
   printer->Print(variables_,
                  "for (int i = 0; i < $name$_.size(); i++) {\n"
                  "  dataSize += com.google.protobuf.CodedOutputStream\n"
-                 "    .computeEnumSizeNoTag($name$_.get(i));\n"
+                 "    .computeEnumSizeNoTag($name$_.getInt(i));\n"
                  "}\n");
   printer->Print("size += dataSize;\n");
   if (descriptor_->is_packed()) {
@@ -1100,7 +1098,7 @@ void RepeatedImmutableEnumFieldGenerator::GenerateKotlinDslMembers(
                  "<$kt_type$, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_ADDER,
diff --git a/src/google/protobuf/compiler/java/immutable/enum_field.h b/src/google/protobuf/compiler/java/full/enum_field.h
similarity index 98%
rename from src/google/protobuf/compiler/java/immutable/enum_field.h
rename to src/google/protobuf/compiler/java/full/enum_field.h
index 625b7c21af..c238fad42c 100644
--- a/src/google/protobuf/compiler/java/immutable/enum_field.h
+++ b/src/google/protobuf/compiler/java/full/enum_field.h
@@ -15,7 +15,7 @@
 #include <string>
 
 #include "absl/container/flat_hash_map.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/io/printer.h"
 
diff --git a/src/google/protobuf/compiler/java/immutable/extension.cc b/src/google/protobuf/compiler/java/full/extension.cc
similarity index 98%
rename from src/google/protobuf/compiler/java/immutable/extension.cc
rename to src/google/protobuf/compiler/java/full/extension.cc
index d731d82400..03fd9d8524 100644
--- a/src/google/protobuf/compiler/java/immutable/extension.cc
+++ b/src/google/protobuf/compiler/java/full/extension.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/extension.h"
+#include "google/protobuf/compiler/java/full/extension.h"
 
 #include "google/protobuf/compiler/java/context.h"
 #include "google/protobuf/compiler/java/doc_comment.h"
diff --git a/src/google/protobuf/compiler/java/immutable/extension.h b/src/google/protobuf/compiler/java/full/extension.h
similarity index 100%
rename from src/google/protobuf/compiler/java/immutable/extension.h
rename to src/google/protobuf/compiler/java/full/extension.h
diff --git a/src/google/protobuf/compiler/java/immutable/field_generator.h b/src/google/protobuf/compiler/java/full/field_generator.h
similarity index 100%
rename from src/google/protobuf/compiler/java/immutable/field_generator.h
rename to src/google/protobuf/compiler/java/full/field_generator.h
diff --git a/src/google/protobuf/compiler/java/immutable/generator_factory.cc b/src/google/protobuf/compiler/java/full/generator_factory.cc
similarity index 89%
rename from src/google/protobuf/compiler/java/immutable/generator_factory.cc
rename to src/google/protobuf/compiler/java/full/generator_factory.cc
index f1b9989449..280987f345 100644
--- a/src/google/protobuf/compiler/java/immutable/generator_factory.cc
+++ b/src/google/protobuf/compiler/java/full/generator_factory.cc
@@ -12,10 +12,10 @@
 #include <memory>
 
 #include "google/protobuf/compiler/java/context.h"
-#include "google/protobuf/compiler/java/immutable/enum.h"
-#include "google/protobuf/compiler/java/immutable/extension.h"
-#include "google/protobuf/compiler/java/immutable/message.h"
-#include "google/protobuf/compiler/java/immutable/service.h"
+#include "google/protobuf/compiler/java/full/enum.h"
+#include "google/protobuf/compiler/java/full/extension.h"
+#include "google/protobuf/compiler/java/full/message.h"
+#include "google/protobuf/compiler/java/full/service.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
diff --git a/src/google/protobuf/compiler/java/immutable/generator_factory.h b/src/google/protobuf/compiler/java/full/generator_factory.h
similarity index 100%
rename from src/google/protobuf/compiler/java/immutable/generator_factory.h
rename to src/google/protobuf/compiler/java/full/generator_factory.h
diff --git a/src/google/protobuf/compiler/java/immutable/make_field_generators.cc b/src/google/protobuf/compiler/java/full/make_field_gens.cc
similarity index 91%
rename from src/google/protobuf/compiler/java/immutable/make_field_generators.cc
rename to src/google/protobuf/compiler/java/full/make_field_gens.cc
index 7636c493bb..08400a68ec 100644
--- a/src/google/protobuf/compiler/java/immutable/make_field_generators.cc
+++ b/src/google/protobuf/compiler/java/full/make_field_gens.cc
@@ -15,12 +15,12 @@
 #include "google/protobuf/compiler/java/context.h"
 #include "google/protobuf/compiler/java/generator_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
-#include "google/protobuf/compiler/java/immutable/enum_field.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
-#include "google/protobuf/compiler/java/immutable/map_field.h"
-#include "google/protobuf/compiler/java/immutable/message_field.h"
-#include "google/protobuf/compiler/java/immutable/primitive_field.h"
-#include "google/protobuf/compiler/java/immutable/string_field.h"
+#include "google/protobuf/compiler/java/full/enum_field.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
+#include "google/protobuf/compiler/java/full/map_field.h"
+#include "google/protobuf/compiler/java/full/message_field.h"
+#include "google/protobuf/compiler/java/full/primitive_field.h"
+#include "google/protobuf/compiler/java/full/string_field.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
diff --git a/src/google/protobuf/compiler/java/immutable/make_field_generators.h b/src/google/protobuf/compiler/java/full/make_field_gens.h
similarity index 77%
rename from src/google/protobuf/compiler/java/immutable/make_field_generators.h
rename to src/google/protobuf/compiler/java/full/make_field_gens.h
index a5dab5dbec..0c02f97823 100644
--- a/src/google/protobuf/compiler/java/immutable/make_field_generators.h
+++ b/src/google/protobuf/compiler/java/full/make_field_gens.h
@@ -5,12 +5,12 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#ifndef GOOGLE_PROTOBUF_COMPILER_JAVA_IMMUTABLE_MAKE_FIELD_GENERATORS_H__
-#define GOOGLE_PROTOBUF_COMPILER_JAVA_IMMUTABLE_MAKE_FIELD_GENERATORS_H__
+#ifndef GOOGLE_PROTOBUF_COMPILER_JAVA_IMMUTABLE_MAKE_FIELD_GENS_H__
+#define GOOGLE_PROTOBUF_COMPILER_JAVA_IMMUTABLE_MAKE_FIELD_GENS_H__
 
 #include "google/protobuf/compiler/java/context.h"
 #include "google/protobuf/compiler/java/generator_common.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
@@ -26,4 +26,4 @@ FieldGeneratorMap<ImmutableFieldGenerator> MakeImmutableFieldGenerators(
 }  // namespace protobuf
 }  // namespace google
 
-#endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_IMMUTABLE_MAKE_FIELD_GENERATORS_H__
+#endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_IMMUTABLE_MAKE_FIELD_GENS_H__
diff --git a/src/google/protobuf/compiler/java/immutable/map_field.cc b/src/google/protobuf/compiler/java/full/map_field.cc
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/map_field.cc
rename to src/google/protobuf/compiler/java/full/map_field.cc
index 02e85874c0..be36f7dc16 100644
--- a/src/google/protobuf/compiler/java/immutable/map_field.cc
+++ b/src/google/protobuf/compiler/java/full/map_field.cc
@@ -5,7 +5,7 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#include "google/protobuf/compiler/java/immutable/map_field.h"
+#include "google/protobuf/compiler/java/full/map_field.h"
 
 #include <string>
 
@@ -15,6 +15,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/io/printer.h"
 
@@ -981,7 +982,7 @@ void ImmutableMapFieldGenerator::GenerateKotlinDslMembers(
       "  @kotlin.jvm.JvmSynthetic\n"
       "  @JvmName(\"get$kt_capitalized_name$Map\")\n"
       "  get() = com.google.protobuf.kotlin.DslMap(\n"
-      "    $kt_dsl_builder$.${$get$capitalized_name$Map$}$()\n"
+      "    $kt_dsl_builder$.${$$kt_property_name$Map$}$\n"
       "  )\n");
 
   WriteFieldDocComment(printer, descriptor_, context_->options(),
diff --git a/src/google/protobuf/compiler/java/immutable/map_field.h b/src/google/protobuf/compiler/java/full/map_field.h
similarity index 97%
rename from src/google/protobuf/compiler/java/immutable/map_field.h
rename to src/google/protobuf/compiler/java/full/map_field.h
index 72613f8659..c41205c4cb 100644
--- a/src/google/protobuf/compiler/java/immutable/map_field.h
+++ b/src/google/protobuf/compiler/java/full/map_field.h
@@ -9,7 +9,7 @@
 #define GOOGLE_PROTOBUF_COMPILER_JAVA_MAP_FIELD_H__
 
 #include "google/protobuf/compiler/java/context.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/io/printer.h"
 
diff --git a/src/google/protobuf/compiler/java/immutable/message.cc b/src/google/protobuf/compiler/java/full/message.cc
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/message.cc
rename to src/google/protobuf/compiler/java/full/message.cc
index 0d75c69efb..10abbb90e8 100644
--- a/src/google/protobuf/compiler/java/immutable/message.cc
+++ b/src/google/protobuf/compiler/java/full/message.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/message.h"
+#include "google/protobuf/compiler/java/full/message.h"
 
 #include <algorithm>
 #include <cstdint>
@@ -28,10 +28,10 @@
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/generator_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
-#include "google/protobuf/compiler/java/immutable/enum.h"
-#include "google/protobuf/compiler/java/immutable/extension.h"
-#include "google/protobuf/compiler/java/immutable/make_field_generators.h"
-#include "google/protobuf/compiler/java/immutable/message_builder.h"
+#include "google/protobuf/compiler/java/full/enum.h"
+#include "google/protobuf/compiler/java/full/extension.h"
+#include "google/protobuf/compiler/java/full/make_field_gens.h"
+#include "google/protobuf/compiler/java/full/message_builder.h"
 #include "google/protobuf/compiler/java/message_serialization.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/descriptor.h"
diff --git a/src/google/protobuf/compiler/java/immutable/message.h b/src/google/protobuf/compiler/java/full/message.h
similarity index 97%
rename from src/google/protobuf/compiler/java/immutable/message.h
rename to src/google/protobuf/compiler/java/full/message.h
index 268f191fcd..3b929b8d3f 100644
--- a/src/google/protobuf/compiler/java/immutable/message.h
+++ b/src/google/protobuf/compiler/java/full/message.h
@@ -17,7 +17,7 @@
 #include <vector>
 
 #include "google/protobuf/compiler/java/generator_factory.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
diff --git a/src/google/protobuf/compiler/java/immutable/message_builder.cc b/src/google/protobuf/compiler/java/full/message_builder.cc
similarity index 98%
rename from src/google/protobuf/compiler/java/immutable/message_builder.cc
rename to src/google/protobuf/compiler/java/full/message_builder.cc
index 3bc0900c16..53de5d3246 100644
--- a/src/google/protobuf/compiler/java/immutable/message_builder.cc
+++ b/src/google/protobuf/compiler/java/full/message_builder.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/message_builder.h"
+#include "google/protobuf/compiler/java/full/message_builder.h"
 
 #include <cstdint>
 #include <memory>
@@ -27,10 +27,10 @@
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/generator_factory.h"
 #include "google/protobuf/compiler/java/helpers.h"
-#include "google/protobuf/compiler/java/immutable/enum.h"
-#include "google/protobuf/compiler/java/immutable/extension.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
-#include "google/protobuf/compiler/java/immutable/make_field_generators.h"
+#include "google/protobuf/compiler/java/full/enum.h"
+#include "google/protobuf/compiler/java/full/extension.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
+#include "google/protobuf/compiler/java/full/make_field_gens.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/io/printer.h"
diff --git a/src/google/protobuf/compiler/java/immutable/message_builder.h b/src/google/protobuf/compiler/java/full/message_builder.h
similarity index 97%
rename from src/google/protobuf/compiler/java/immutable/message_builder.h
rename to src/google/protobuf/compiler/java/full/message_builder.h
index ad2b378721..f63f8f4b0a 100644
--- a/src/google/protobuf/compiler/java/immutable/message_builder.h
+++ b/src/google/protobuf/compiler/java/full/message_builder.h
@@ -17,7 +17,7 @@
 #include <vector>
 
 #include "absl/container/btree_map.h"
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
diff --git a/src/google/protobuf/compiler/java/immutable/message_field.cc b/src/google/protobuf/compiler/java/full/message_field.cc
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/message_field.cc
rename to src/google/protobuf/compiler/java/full/message_field.cc
index 1b76fc2f63..54ae8dea17 100644
--- a/src/google/protobuf/compiler/java/immutable/message_field.cc
+++ b/src/google/protobuf/compiler/java/full/message_field.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/message_field.h"
+#include "google/protobuf/compiler/java/full/message_field.h"
 
 #include <string>
 
@@ -378,10 +378,10 @@ void ImmutableMessageFieldGenerator::GenerateKotlinDslMembers(
   printer->Print(variables_,
                  "$kt_deprecation$public var $kt_name$: $kt_type$\n"
                  "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
+                 "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
                  "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
                  "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
+                 "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
                  "  }\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, CLEARER,
@@ -1376,7 +1376,7 @@ void RepeatedImmutableMessageFieldGenerator::GenerateKotlinDslMembers(
                  "<$kt_type$, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_ADDER,
diff --git a/src/google/protobuf/compiler/java/immutable/message_field.h b/src/google/protobuf/compiler/java/full/message_field.h
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/message_field.h
rename to src/google/protobuf/compiler/java/full/message_field.h
index ee3c4e5289..709ea4309d 100644
--- a/src/google/protobuf/compiler/java/immutable/message_field.h
+++ b/src/google/protobuf/compiler/java/full/message_field.h
@@ -14,7 +14,7 @@
 
 #include <string>
 
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/io/printer.h"
 
diff --git a/src/google/protobuf/compiler/java/immutable/primitive_field.cc b/src/google/protobuf/compiler/java/full/primitive_field.cc
similarity index 97%
rename from src/google/protobuf/compiler/java/immutable/primitive_field.cc
rename to src/google/protobuf/compiler/java/full/primitive_field.cc
index eb31a7b756..b9fe799f4d 100644
--- a/src/google/protobuf/compiler/java/immutable/primitive_field.cc
+++ b/src/google/protobuf/compiler/java/full/primitive_field.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/primitive_field.h"
+#include "google/protobuf/compiler/java/full/primitive_field.h"
 
 #include <cstdint>
 #include <string>
@@ -291,14 +291,27 @@ void ImmutablePrimitiveFieldGenerator::GenerateKotlinDslMembers(
     io::Printer* printer) const {
   WriteFieldDocComment(printer, descriptor_, context_->options(),
                        /* kdoc */ true);
-  printer->Print(variables_,
-                 "$kt_deprecation$public var $kt_name$: $kt_type$\n"
-                 "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
-                 "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
-                 "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
-                 "  }\n");
+  if (descriptor_->name() == "is_initialized") {
+    printer->Print(
+        variables_,
+        "// TODO: remove this hack; we should access properties\n"
+        "$kt_deprecation$public var $kt_name$: $kt_type$\n"
+        "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
+        "  get() = $kt_dsl_builder$.${$get$kt_capitalized_name$$}$()\n"
+        "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
+        "  set(value) {\n"
+        "    $kt_dsl_builder$.${$set$kt_capitalized_name$$}$(value)\n"
+        "  }\n");
+  } else {
+    printer->Print(variables_,
+                   "$kt_deprecation$public var $kt_name$: $kt_type$\n"
+                   "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
+                   "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
+                   "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
+                   "  set(value) {\n"
+                   "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
+                   "  }\n");
+  }
 
   WriteFieldAccessorDocComment(printer, descriptor_, CLEARER,
                                context_->options(),
@@ -848,7 +861,7 @@ void RepeatedImmutablePrimitiveFieldGenerator::GenerateKotlinDslMembers(
                  "<$kt_type$, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_ADDER,
diff --git a/src/google/protobuf/compiler/java/immutable/primitive_field.h b/src/google/protobuf/compiler/java/full/primitive_field.h
similarity index 98%
rename from src/google/protobuf/compiler/java/immutable/primitive_field.h
rename to src/google/protobuf/compiler/java/full/primitive_field.h
index 9aa52bfb8e..6533228ce3 100644
--- a/src/google/protobuf/compiler/java/immutable/primitive_field.h
+++ b/src/google/protobuf/compiler/java/full/primitive_field.h
@@ -14,7 +14,7 @@
 
 #include <string>
 
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
diff --git a/src/google/protobuf/compiler/java/immutable/service.cc b/src/google/protobuf/compiler/java/full/service.cc
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/service.cc
rename to src/google/protobuf/compiler/java/full/service.cc
index f93f9136d7..97d70966b4 100644
--- a/src/google/protobuf/compiler/java/immutable/service.cc
+++ b/src/google/protobuf/compiler/java/full/service.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/service.h"
+#include "google/protobuf/compiler/java/full/service.h"
 
 #include "absl/log/absl_log.h"
 #include "absl/strings/str_cat.h"
diff --git a/src/google/protobuf/compiler/java/immutable/service.h b/src/google/protobuf/compiler/java/full/service.h
similarity index 100%
rename from src/google/protobuf/compiler/java/immutable/service.h
rename to src/google/protobuf/compiler/java/full/service.h
diff --git a/src/google/protobuf/compiler/java/immutable/string_field.cc b/src/google/protobuf/compiler/java/full/string_field.cc
similarity index 99%
rename from src/google/protobuf/compiler/java/immutable/string_field.cc
rename to src/google/protobuf/compiler/java/full/string_field.cc
index c9ac5f4e7c..d5b5d582bc 100644
--- a/src/google/protobuf/compiler/java/immutable/string_field.cc
+++ b/src/google/protobuf/compiler/java/full/string_field.cc
@@ -10,7 +10,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/immutable/string_field.h"
+#include "google/protobuf/compiler/java/full/string_field.h"
 
 #include <cstdint>
 #include <string>
@@ -22,6 +22,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/wire_format.h"
@@ -372,10 +373,10 @@ void ImmutableStringFieldGenerator::GenerateKotlinDslMembers(
   printer->Print(variables_,
                  "$kt_deprecation$public var $kt_name$: kotlin.String\n"
                  "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
+                 "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
                  "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
                  "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
+                 "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
                  "  }\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, CLEARER,
@@ -992,7 +993,7 @@ void RepeatedImmutableStringFieldGenerator::GenerateKotlinDslMembers(
                  "<kotlin.String, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   // List<String>.add(String)
diff --git a/src/google/protobuf/compiler/java/immutable/string_field.h b/src/google/protobuf/compiler/java/full/string_field.h
similarity index 98%
rename from src/google/protobuf/compiler/java/immutable/string_field.h
rename to src/google/protobuf/compiler/java/full/string_field.h
index cf95be0da8..1d2d1b76b5 100644
--- a/src/google/protobuf/compiler/java/immutable/string_field.h
+++ b/src/google/protobuf/compiler/java/full/string_field.h
@@ -15,7 +15,7 @@
 
 #include <string>
 
-#include "google/protobuf/compiler/java/immutable/field_generator.h"
+#include "google/protobuf/compiler/java/full/field_generator.h"
 #include "google/protobuf/descriptor.h"
 
 namespace google {
diff --git a/src/google/protobuf/compiler/java/generator.h b/src/google/protobuf/compiler/java/generator.h
index bd510c6995..53cb616072 100644
--- a/src/google/protobuf/compiler/java/generator.h
+++ b/src/google/protobuf/compiler/java/generator.h
@@ -21,6 +21,7 @@
 #include "google/protobuf/compiler/code_generator.h"
 #include "google/protobuf/compiler/java/java_features.pb.h"
 #include "google/protobuf/descriptor.pb.h"
+#include "google/protobuf/port.h"
 
 // Must be included last.
 #include "google/protobuf/port_def.inc"
@@ -62,7 +63,7 @@ class PROTOC_EXPORT JavaGenerator : public CodeGenerator {
   using CodeGenerator::GetResolvedSourceFeatures;
 
  private:
-  bool opensource_runtime_ = PROTO2_IS_OSS;
+  bool opensource_runtime_ = google::protobuf::internal::IsOss();
 };
 
 }  // namespace java
diff --git a/src/google/protobuf/compiler/java/helpers.cc b/src/google/protobuf/compiler/java/helpers.cc
index 826d9f8344..8deb2dcec3 100644
--- a/src/google/protobuf/compiler/java/helpers.cc
+++ b/src/google/protobuf/compiler/java/helpers.cc
@@ -878,86 +878,6 @@ void WriteUInt32ToUtf16CharSequence(uint32_t number,
   output->push_back(static_cast<uint16_t>(number));
 }
 
-int GetExperimentalJavaFieldTypeForSingular(const FieldDescriptor* field) {
-  // j/c/g/protobuf/FieldType.java lists field types in a slightly different
-  // order from FieldDescriptor::Type so we can't do a simple cast.
-  //
-  // TODO: Make j/c/g/protobuf/FieldType.java follow the same order.
-  int result = field->type();
-  if (result == FieldDescriptor::TYPE_GROUP) {
-    return 17;
-  } else if (result < FieldDescriptor::TYPE_GROUP) {
-    return result - 1;
-  } else {
-    return result - 2;
-  }
-}
-
-int GetExperimentalJavaFieldTypeForRepeated(const FieldDescriptor* field) {
-  if (field->type() == FieldDescriptor::TYPE_GROUP) {
-    return 49;
-  } else {
-    return GetExperimentalJavaFieldTypeForSingular(field) + 18;
-  }
-}
-
-int GetExperimentalJavaFieldTypeForPacked(const FieldDescriptor* field) {
-  int result = field->type();
-  if (result < FieldDescriptor::TYPE_STRING) {
-    return result + 34;
-  } else if (result > FieldDescriptor::TYPE_BYTES) {
-    return result + 30;
-  } else {
-    ABSL_LOG(FATAL) << field->full_name() << " can't be packed.";
-    return 0;
-  }
-}
-
-int GetExperimentalJavaFieldType(const FieldDescriptor* field) {
-  static const int kMapFieldType = 50;
-  static const int kOneofFieldTypeOffset = 51;
-
-  static const int kRequiredBit = 0x100;
-  static const int kUtf8CheckBit = 0x200;
-  static const int kCheckInitialized = 0x400;
-  static const int kLegacyEnumIsClosedBit = 0x800;
-  static const int kHasHasBit = 0x1000;
-  int extra_bits = field->is_required() ? kRequiredBit : 0;
-  if (field->type() == FieldDescriptor::TYPE_STRING && CheckUtf8(field)) {
-    extra_bits |= kUtf8CheckBit;
-  }
-  if (field->is_required() || (GetJavaType(field) == JAVATYPE_MESSAGE &&
-                               HasRequiredFields(field->message_type()))) {
-    extra_bits |= kCheckInitialized;
-  }
-  if (HasHasbit(field)) {
-    extra_bits |= kHasHasBit;
-  }
-  if (GetJavaType(field) == JAVATYPE_ENUM && !SupportUnknownEnumValue(field)) {
-    extra_bits |= kLegacyEnumIsClosedBit;
-  }
-
-  if (field->is_map()) {
-    if (!SupportUnknownEnumValue(MapValueField(field))) {
-      const FieldDescriptor* value = field->message_type()->map_value();
-      if (GetJavaType(value) == JAVATYPE_ENUM) {
-        extra_bits |= kLegacyEnumIsClosedBit;
-      }
-    }
-    return kMapFieldType | extra_bits;
-  } else if (field->is_packed()) {
-    return GetExperimentalJavaFieldTypeForPacked(field) | extra_bits;
-  } else if (field->is_repeated()) {
-    return GetExperimentalJavaFieldTypeForRepeated(field) | extra_bits;
-  } else if (IsRealOneof(field)) {
-    return (GetExperimentalJavaFieldTypeForSingular(field) +
-            kOneofFieldTypeOffset) |
-           extra_bits;
-  } else {
-    return GetExperimentalJavaFieldTypeForSingular(field) | extra_bits;
-  }
-}
-
 // Escape a UTF-16 character to be embedded in a Java string.
 void EscapeUtf16ToString(uint16_t code, std::string* output) {
   if (code == '\t') {
diff --git a/src/google/protobuf/compiler/java/helpers.h b/src/google/protobuf/compiler/java/helpers.h
index ed27eae1d5..d99e085a65 100644
--- a/src/google/protobuf/compiler/java/helpers.h
+++ b/src/google/protobuf/compiler/java/helpers.h
@@ -16,8 +16,6 @@
 #include <string>
 
 #include "absl/strings/string_view.h"
-#include "google/protobuf/compiler/java/generator.h"
-#include "google/protobuf/compiler/java/java_features.pb.h"
 #include "google/protobuf/compiler/java/names.h"
 #include "google/protobuf/compiler/java/options.h"
 #include "google/protobuf/descriptor.h"
@@ -80,8 +78,7 @@ std::string UniqueFileScopeIdentifier(const Descriptor* descriptor);
 // Gets the unqualified class name for the file.  For each .proto file, there
 // will be one Java class containing all the immutable messages and another
 // Java class containing all the mutable messages.
-// TODO: remove the default value after updating client code.
-std::string FileClassName(const FileDescriptor* file, bool immutable = true);
+std::string FileClassName(const FileDescriptor* file, bool immutable);
 
 // Returns the file's Java package name.
 std::string FileJavaPackage(const FileDescriptor* file, bool immutable,
@@ -344,18 +341,6 @@ inline bool HasHasbit(const FieldDescriptor* descriptor) {
   return internal::cpp::HasHasbit(descriptor);
 }
 
-// Whether unknown enum values are kept (i.e., not stored in UnknownFieldSet
-// but in the message and can be queried using additional getters that return
-// ints.
-inline bool SupportUnknownEnumValue(const FieldDescriptor* field) {
-  if (JavaGenerator::GetResolvedSourceFeatures(*field)
-          .GetExtension(pb::java)
-          .legacy_closed_enum()) {
-    return false;
-  }
-  return field->enum_type() != nullptr && !field->enum_type()->is_closed();
-}
-
 // Check whether a message has repeated fields.
 bool HasRepeatedFields(const Descriptor* descriptor);
 
@@ -375,18 +360,6 @@ inline bool IsWrappersProtoFile(const FileDescriptor* descriptor) {
   return descriptor->name() == "google/protobuf/wrappers.proto";
 }
 
-inline bool CheckUtf8(const FieldDescriptor* descriptor) {
-  if (JavaGenerator::GetResolvedSourceFeatures(*descriptor)
-          .GetExtension(pb::java)
-          .utf8_validation() == pb::JavaFeatures::VERIFY) {
-    return true;
-  }
-  return JavaGenerator::GetResolvedSourceFeatures(*descriptor)
-                 .utf8_validation() == FeatureSet::VERIFY ||
-         // For legacy syntax. This is not allowed under Editions.
-         descriptor->file()->options().java_string_check_utf8();
-}
-
 void WriteUInt32ToUtf16CharSequence(uint32_t number,
                                     std::vector<uint16_t>* output);
 
@@ -398,16 +371,6 @@ inline void WriteIntToUtf16CharSequence(int value,
 // Escape a UTF-16 character so it can be embedded in a Java string literal.
 void EscapeUtf16ToString(uint16_t code, std::string* output);
 
-// Only the lowest two bytes of the return value are used. The lowest byte
-// is the integer value of a j/c/g/protobuf/FieldType enum. For the other
-// byte:
-//    bit 0: whether the field is required.
-//    bit 1: whether the field requires UTF-8 validation.
-//    bit 2: whether the field needs isInitialized check.
-//    bit 3: whether the field is a map field with proto2 enum value.
-//    bits 4-7: unused
-int GetExperimentalJavaFieldType(const FieldDescriptor* field);
-
 // To get the total number of entries need to be built for experimental runtime
 // and the first field number that are not in the table part
 std::pair<int, int> GetTableDrivenNumberOfEntriesAndLookUpStartFieldNumber(
diff --git a/src/google/protobuf/compiler/java/internal_helpers.cc b/src/google/protobuf/compiler/java/internal_helpers.cc
new file mode 100644
index 0000000000..06dae866c4
--- /dev/null
+++ b/src/google/protobuf/compiler/java/internal_helpers.cc
@@ -0,0 +1,114 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+
+#include "google/protobuf/compiler/java/internal_helpers.h"
+
+#include "absl/log/absl_log.h"
+#include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/name_resolver.h"
+#include "google/protobuf/descriptor.pb.h"
+
+// Must be last.
+#include "google/protobuf/port_def.inc"
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace java {
+namespace {
+
+int GetExperimentalJavaFieldTypeForSingular(const FieldDescriptor* field) {
+  // j/c/g/protobuf/FieldType.java lists field types in a slightly different
+  // order from FieldDescriptor::Type so we can't do a simple cast.
+  //
+  // TODO: Make j/c/g/protobuf/FieldType.java follow the same order.
+  int result = field->type();
+  if (result == FieldDescriptor::TYPE_GROUP) {
+    return 17;
+  } else if (result < FieldDescriptor::TYPE_GROUP) {
+    return result - 1;
+  } else {
+    return result - 2;
+  }
+}
+
+int GetExperimentalJavaFieldTypeForRepeated(const FieldDescriptor* field) {
+  if (field->type() == FieldDescriptor::TYPE_GROUP) {
+    return 49;
+  } else {
+    return GetExperimentalJavaFieldTypeForSingular(field) + 18;
+  }
+}
+
+int GetExperimentalJavaFieldTypeForPacked(const FieldDescriptor* field) {
+  int result = field->type();
+  if (result < FieldDescriptor::TYPE_STRING) {
+    return result + 34;
+  } else if (result > FieldDescriptor::TYPE_BYTES) {
+    return result + 30;
+  } else {
+    ABSL_LOG(FATAL) << field->full_name() << " can't be packed.";
+    return 0;
+  }
+}
+}  // namespace
+
+int GetExperimentalJavaFieldType(const FieldDescriptor* field) {
+  static const int kMapFieldType = 50;
+  static const int kOneofFieldTypeOffset = 51;
+
+  static const int kRequiredBit = 0x100;
+  static const int kUtf8CheckBit = 0x200;
+  static const int kCheckInitialized = 0x400;
+  static const int kLegacyEnumIsClosedBit = 0x800;
+  static const int kHasHasBit = 0x1000;
+  int extra_bits = field->is_required() ? kRequiredBit : 0;
+  if (field->type() == FieldDescriptor::TYPE_STRING && CheckUtf8(field)) {
+    extra_bits |= kUtf8CheckBit;
+  }
+  if (field->is_required() || (GetJavaType(field) == JAVATYPE_MESSAGE &&
+                               HasRequiredFields(field->message_type()))) {
+    extra_bits |= kCheckInitialized;
+  }
+  if (HasHasbit(field)) {
+    extra_bits |= kHasHasBit;
+  }
+  if (GetJavaType(field) == JAVATYPE_ENUM && !SupportUnknownEnumValue(field)) {
+    extra_bits |= kLegacyEnumIsClosedBit;
+  }
+
+  if (field->is_map()) {
+    if (!SupportUnknownEnumValue(MapValueField(field))) {
+      const FieldDescriptor* value = field->message_type()->map_value();
+      if (GetJavaType(value) == JAVATYPE_ENUM) {
+        extra_bits |= kLegacyEnumIsClosedBit;
+      }
+    }
+    return kMapFieldType | extra_bits;
+  } else if (field->is_packed()) {
+    return GetExperimentalJavaFieldTypeForPacked(field) | extra_bits;
+  } else if (field->is_repeated()) {
+    return GetExperimentalJavaFieldTypeForRepeated(field) | extra_bits;
+  } else if (IsRealOneof(field)) {
+    return (GetExperimentalJavaFieldTypeForSingular(field) +
+            kOneofFieldTypeOffset) |
+           extra_bits;
+  } else {
+    return GetExperimentalJavaFieldTypeForSingular(field) | extra_bits;
+  }
+}
+
+}  // namespace java
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
+
+#include "google/protobuf/port_undef.inc"
diff --git a/src/google/protobuf/compiler/java/internal_helpers.h b/src/google/protobuf/compiler/java/internal_helpers.h
new file mode 100644
index 0000000000..607669b26a
--- /dev/null
+++ b/src/google/protobuf/compiler/java/internal_helpers.h
@@ -0,0 +1,70 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+// Author: kenton@google.com (Kenton Varda)
+//  Based on original Protocol Buffers design by
+//  Sanjay Ghemawat, Jeff Dean, and others.
+
+#ifndef GOOGLE_PROTOBUF_COMPILER_JAVA_INTERNAL_HELPERS_H__
+#define GOOGLE_PROTOBUF_COMPILER_JAVA_INTERNAL_HELPERS_H__
+
+#include "google/protobuf/compiler/java/generator.h"
+#include "google/protobuf/compiler/java/java_features.pb.h"
+#include "google/protobuf/compiler/java/names.h"
+#include "google/protobuf/descriptor.h"
+#include "google/protobuf/descriptor.pb.h"
+
+// Must be last.
+#include "google/protobuf/port_def.inc"
+
+namespace google {
+namespace protobuf {
+namespace compiler {
+namespace java {
+
+// Whether unknown enum values are kept (i.e., not stored in UnknownFieldSet
+// but in the message and can be queried using additional getters that return
+// ints.
+inline bool SupportUnknownEnumValue(const FieldDescriptor* field) {
+  if (JavaGenerator::GetResolvedSourceFeatures(*field)
+          .GetExtension(pb::java)
+          .legacy_closed_enum()) {
+    return false;
+  }
+  return field->enum_type() != nullptr && !field->enum_type()->is_closed();
+}
+
+inline bool CheckUtf8(const FieldDescriptor* descriptor) {
+  if (JavaGenerator::GetResolvedSourceFeatures(*descriptor)
+          .GetExtension(pb::java)
+          .utf8_validation() == pb::JavaFeatures::VERIFY) {
+    return true;
+  }
+  return JavaGenerator::GetResolvedSourceFeatures(*descriptor)
+                 .utf8_validation() == FeatureSet::VERIFY ||
+         // For legacy syntax. This is not allowed under Editions.
+         descriptor->file()->options().java_string_check_utf8();
+}
+
+
+// Only the lowest two bytes of the return value are used. The lowest byte
+// is the integer value of a j/c/g/protobuf/FieldType enum. For the other
+// byte:
+//    bit 0: whether the field is required.
+//    bit 1: whether the field requires UTF-8 validation.
+//    bit 2: whether the field needs isInitialized check.
+//    bit 3: whether the field is a map field with proto2 enum value.
+//    bits 4-7: unused
+int GetExperimentalJavaFieldType(const FieldDescriptor* field);
+
+}  // namespace java
+}  // namespace compiler
+}  // namespace protobuf
+}  // namespace google
+
+#include "google/protobuf/port_undef.inc"
+#endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_INTERNAL_HELPERS_H__
diff --git a/src/google/protobuf/compiler/java/java_features.pb.cc b/src/google/protobuf/compiler/java/java_features.pb.cc
index 799299210b..d6b304f1b2 100644
--- a/src/google/protobuf/compiler/java/java_features.pb.cc
+++ b/src/google/protobuf/compiler/java/java_features.pb.cc
@@ -292,27 +292,26 @@ PROTOBUF_NOINLINE void JavaFeatures::Clear() {
 }
 
 ::size_t JavaFeatures::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:pb.JavaFeatures)
+  // @@protoc_insertion_point(message_byte_size_start:pb.JavaFeatures)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // optional bool legacy_closed_enum = 1 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000001u) {
       total_size += 2;
     }
-
     // optional .pb.JavaFeatures.Utf8Validation utf8_validation = 2 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_utf8_validation());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
diff --git a/src/google/protobuf/compiler/java/lite/BUILD.bazel b/src/google/protobuf/compiler/java/lite/BUILD.bazel
index 7904d4b42e..ec4b222aa6 100644
--- a/src/google/protobuf/compiler/java/lite/BUILD.bazel
+++ b/src/google/protobuf/compiler/java/lite/BUILD.bazel
@@ -3,7 +3,7 @@ cc_library(
     srcs = [
         "enum_field.cc",
         "extension.cc",
-        "make_field_generators.cc",
+        "make_field_gens.cc",
         "map_field.cc",
         "message_field.cc",
         "primitive_field.cc",
@@ -11,7 +11,7 @@ cc_library(
     ],
     hdrs = [
         "field_generator.h",
-        "make_field_generators.h",
+        "make_field_gens.h",
         # We don't actually want to put the remaining headers in `hdrs`.
         # They are logically private, and should be in srcs=[], but
         # unfortunately `strip_include_prefix` doesn't have any effect
@@ -30,6 +30,7 @@ cc_library(
         "//src/google/protobuf:port",
         "//src/google/protobuf/compiler/java:generator_common",
         "//src/google/protobuf/compiler/java:helpers",
+        "//src/google/protobuf/compiler/java:internal_helpers",
         "//src/google/protobuf/io:printer",
         "@com_google_absl//absl/container:flat_hash_map",
         "@com_google_absl//absl/log:absl_check",
@@ -66,7 +67,8 @@ cc_library(
         "//src/google/protobuf:port",
         "//src/google/protobuf/compiler/java:generator_common",
         "//src/google/protobuf/compiler/java:helpers",
-        "//src/google/protobuf/compiler/java/immutable:service",
+        "//src/google/protobuf/compiler/java:internal_helpers",
+        "//src/google/protobuf/compiler/java/full:service",
         "//src/google/protobuf/io",
         "//src/google/protobuf/io:printer",
         "@com_google_absl//absl/container:btree",
diff --git a/src/google/protobuf/compiler/java/lite/enum_field.cc b/src/google/protobuf/compiler/java/lite/enum_field.cc
index f2fb340b1b..bffec06347 100644
--- a/src/google/protobuf/compiler/java/lite/enum_field.cc
+++ b/src/google/protobuf/compiler/java/lite/enum_field.cc
@@ -17,11 +17,11 @@
 #include "absl/container/flat_hash_map.h"
 #include "absl/log/absl_check.h"
 #include "absl/strings/str_cat.h"
-#include "absl/strings/str_join.h"
 #include "google/protobuf/compiler/java/context.h"
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/wire_format.h"
@@ -308,10 +308,10 @@ void ImmutableEnumFieldLiteGenerator::GenerateKotlinDslMembers(
   printer->Print(variables_,
                  "$kt_deprecation$public var $kt_name$: $kt_type$\n"
                  "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
+                 "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
                  "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
                  "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
+                 "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
                  "  }\n");
 
   if (SupportUnknownEnumValue(descriptor_)) {
@@ -319,10 +319,10 @@ void ImmutableEnumFieldLiteGenerator::GenerateKotlinDslMembers(
         variables_,
         "$kt_deprecation$public var $kt_name$Value: kotlin.Int\n"
         "  @JvmName(\"${$get$kt_capitalized_name$Value$}$\")\n"
-        "  get() = $kt_dsl_builder$.${$get$capitalized_name$Value$}$()\n"
+        "  get() = $kt_dsl_builder$.${$$kt_property_name$Value$}$\n"
         "  @JvmName(\"${$set$kt_capitalized_name$Value$}$\")\n"
         "  set(value) {\n"
-        "    $kt_dsl_builder$.${$set$capitalized_name$Value$}$(value)\n"
+        "    $kt_dsl_builder$.${$$kt_property_name$Value$}$ = value\n"
         "  }\n");
   }
 
@@ -597,12 +597,12 @@ void RepeatedImmutableEnumFieldLiteGenerator::GenerateMembers(
       variables_,
       "private com.google.protobuf.Internal.IntList $name$_;\n"
       "private static final "
-      "com.google.protobuf.Internal.ListAdapter.Converter<\n"
-      "    java.lang.Integer, $type$> $name$_converter_ =\n"
-      "        new com.google.protobuf.Internal.ListAdapter.Converter<\n"
-      "            java.lang.Integer, $type$>() {\n"
+      "com.google.protobuf.Internal.IntListAdapter.IntConverter<\n"
+      "    $type$> $name$_converter_ =\n"
+      "        new com.google.protobuf.Internal.IntListAdapter.IntConverter<\n"
+      "            $type$>() {\n"
       "          @java.lang.Override\n"
-      "          public $type$ convert(java.lang.Integer from) {\n"
+      "          public $type$ convert(int from) {\n"
       "            $type$ result = $type$.forNumber(from);\n"
       "            return result == null ? $unknown$ : result;\n"
       "          }\n"
@@ -610,14 +610,13 @@ void RepeatedImmutableEnumFieldLiteGenerator::GenerateMembers(
   PrintExtraFieldInfo(variables_, printer);
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_GETTER,
                                context_->options());
-  printer->Print(
-      variables_,
-      "@java.lang.Override\n"
-      "$deprecation$public java.util.List<$type$> "
-      "${$get$capitalized_name$List$}$() {\n"
-      "  return new com.google.protobuf.Internal.ListAdapter<\n"
-      "      java.lang.Integer, $type$>($name$_, $name$_converter_);\n"
-      "}\n");
+  printer->Print(variables_,
+                 "@java.lang.Override\n"
+                 "$deprecation$public java.util.List<$type$> "
+                 "${$get$capitalized_name$List$}$() {\n"
+                 "  return new com.google.protobuf.Internal.IntListAdapter<\n"
+                 "      $type$>($name$_, $name$_converter_);\n"
+                 "}\n");
   printer->Annotate("{", "}", descriptor_);
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_COUNT,
                                context_->options());
@@ -914,7 +913,7 @@ void RepeatedImmutableEnumFieldLiteGenerator::GenerateKotlinDslMembers(
                  "<$kt_type$, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_ADDER,
diff --git a/src/google/protobuf/compiler/java/lite/generator_factory.cc b/src/google/protobuf/compiler/java/lite/generator_factory.cc
index c3f52fe92a..8b9ddb4518 100644
--- a/src/google/protobuf/compiler/java/lite/generator_factory.cc
+++ b/src/google/protobuf/compiler/java/lite/generator_factory.cc
@@ -12,7 +12,7 @@
 #include <memory>
 
 #include "google/protobuf/compiler/java/context.h"
-#include "google/protobuf/compiler/java/immutable/service.h"
+#include "google/protobuf/compiler/java/full/service.h"
 #include "google/protobuf/compiler/java/lite/enum.h"
 #include "google/protobuf/compiler/java/lite/extension.h"
 #include "google/protobuf/compiler/java/lite/message.h"
diff --git a/src/google/protobuf/compiler/java/lite/make_field_generators.cc b/src/google/protobuf/compiler/java/lite/make_field_gens.cc
similarity index 98%
rename from src/google/protobuf/compiler/java/lite/make_field_generators.cc
rename to src/google/protobuf/compiler/java/lite/make_field_gens.cc
index 6071662c58..c4b92deac3 100644
--- a/src/google/protobuf/compiler/java/lite/make_field_generators.cc
+++ b/src/google/protobuf/compiler/java/lite/make_field_gens.cc
@@ -9,7 +9,7 @@
 //  Based on original Protocol Buffers design by
 //  Sanjay Ghemawat, Jeff Dean, and others.
 
-#include "google/protobuf/compiler/java/lite/make_field_generators.h"
+#include "google/protobuf/compiler/java/lite/make_field_gens.h"
 
 #include <memory>
 #include <utility>
diff --git a/src/google/protobuf/compiler/java/lite/make_field_generators.h b/src/google/protobuf/compiler/java/lite/make_field_gens.h
similarity index 80%
rename from src/google/protobuf/compiler/java/lite/make_field_generators.h
rename to src/google/protobuf/compiler/java/lite/make_field_gens.h
index 436c3f896e..ebc9f22e05 100644
--- a/src/google/protobuf/compiler/java/lite/make_field_generators.h
+++ b/src/google/protobuf/compiler/java/lite/make_field_gens.h
@@ -5,8 +5,8 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#ifndef GOOGLE_PROTOBUF_COMPILER_JAVA_LITE_MAKE_FIELD_GENERATORS_H__
-#define GOOGLE_PROTOBUF_COMPILER_JAVA_LITE_MAKE_FIELD_GENERATORS_H__
+#ifndef GOOGLE_PROTOBUF_COMPILER_JAVA_LITE_MAKE_FIELD_GENS_H__
+#define GOOGLE_PROTOBUF_COMPILER_JAVA_LITE_MAKE_FIELD_GENS_H__
 
 #include <memory>
 #include <vector>
@@ -29,4 +29,4 @@ FieldGeneratorMap<ImmutableFieldLiteGenerator> MakeImmutableFieldLiteGenerators(
 }  // namespace protobuf
 }  // namespace google
 
-#endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_LITE_MAKE_FIELD_GENERATORS_H__
+#endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_LITE_MAKE_FIELD_GENS_H__
diff --git a/src/google/protobuf/compiler/java/lite/map_field.cc b/src/google/protobuf/compiler/java/lite/map_field.cc
index 74fc93f347..7ab58c50ba 100644
--- a/src/google/protobuf/compiler/java/lite/map_field.cc
+++ b/src/google/protobuf/compiler/java/lite/map_field.cc
@@ -14,6 +14,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/io/printer.h"
 
@@ -857,7 +858,7 @@ void ImmutableMapFieldLiteGenerator::GenerateKotlinDslMembers(
       "  @kotlin.jvm.JvmSynthetic\n"
       "  @JvmName(\"get$kt_capitalized_name$Map\")\n"
       "  get() = com.google.protobuf.kotlin.DslMap(\n"
-      "    $kt_dsl_builder$.${$get$capitalized_name$Map$}$()\n"
+      "    $kt_dsl_builder$.${$$kt_property_name$Map$}$\n"
       "  )\n");
 
   WriteFieldDocComment(printer, descriptor_, context_->options(),
diff --git a/src/google/protobuf/compiler/java/lite/message.cc b/src/google/protobuf/compiler/java/lite/message.cc
index 3363162dc1..81e95242aa 100644
--- a/src/google/protobuf/compiler/java/lite/message.cc
+++ b/src/google/protobuf/compiler/java/lite/message.cc
@@ -33,7 +33,7 @@
 #include "google/protobuf/compiler/java/helpers.h"
 #include "google/protobuf/compiler/java/lite/enum.h"
 #include "google/protobuf/compiler/java/lite/extension.h"
-#include "google/protobuf/compiler/java/lite/make_field_generators.h"
+#include "google/protobuf/compiler/java/lite/make_field_gens.h"
 #include "google/protobuf/compiler/java/lite/message_builder.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/descriptor.pb.h"
diff --git a/src/google/protobuf/compiler/java/lite/message_builder.cc b/src/google/protobuf/compiler/java/lite/message_builder.cc
index 9ae4081555..c5dac22bb5 100644
--- a/src/google/protobuf/compiler/java/lite/message_builder.cc
+++ b/src/google/protobuf/compiler/java/lite/message_builder.cc
@@ -20,7 +20,7 @@
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
 #include "google/protobuf/compiler/java/lite/enum.h"
-#include "google/protobuf/compiler/java/lite/make_field_generators.h"
+#include "google/protobuf/compiler/java/lite/make_field_gens.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/io/printer.h"
diff --git a/src/google/protobuf/compiler/java/lite/message_field.cc b/src/google/protobuf/compiler/java/lite/message_field.cc
index 7c5cc3cf77..84a10b9888 100644
--- a/src/google/protobuf/compiler/java/lite/message_field.cc
+++ b/src/google/protobuf/compiler/java/lite/message_field.cc
@@ -19,6 +19,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/io/printer.h"
 #include "google/protobuf/wire_format.h"
@@ -283,10 +284,10 @@ void ImmutableMessageFieldLiteGenerator::GenerateKotlinDslMembers(
   printer->Print(variables_,
                  "$kt_deprecation$public var $kt_name$: $kt_type$\n"
                  "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
+                 "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
                  "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
                  "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
+                 "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
                  "  }\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, CLEARER,
@@ -818,7 +819,7 @@ void RepeatedImmutableMessageFieldLiteGenerator::GenerateKotlinDslMembers(
                  "<$kt_type$, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_ADDER,
diff --git a/src/google/protobuf/compiler/java/lite/primitive_field.cc b/src/google/protobuf/compiler/java/lite/primitive_field.cc
index 69924c9c83..838df002ce 100644
--- a/src/google/protobuf/compiler/java/lite/primitive_field.cc
+++ b/src/google/protobuf/compiler/java/lite/primitive_field.cc
@@ -21,6 +21,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/wire_format.h"
 
@@ -217,10 +218,9 @@ void ImmutablePrimitiveFieldLiteGenerator::GenerateMembers(
         "private static final $field_type$ $bytes_default$ = $default$;\n");
   }
   if (!context_->options().opensource_runtime) {
-    printer->Print(
-        variables_,
-        "@com.google.protobuf.ProtoField(\n"
-        "  isRequired=$required$)\n");
+    printer->Print(variables_,
+                   "@com.google.protobuf.ProtoField(\n"
+                   "  isRequired=$required$)\n");
     if (HasHasbit(descriptor_)) {
       printer->Print(variables_,
                      "@com.google.protobuf.ProtoPresenceCheckedField(\n"
@@ -329,14 +329,27 @@ void ImmutablePrimitiveFieldLiteGenerator::GenerateBuilderMembers(
 void ImmutablePrimitiveFieldLiteGenerator::GenerateKotlinDslMembers(
     io::Printer* printer) const {
   WriteFieldDocComment(printer, descriptor_, context_->options());
-  printer->Print(variables_,
-                 "$kt_deprecation$public var $kt_name$: $kt_type$\n"
-                 "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
-                 "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
-                 "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
-                 "  }\n");
+  if (descriptor_->name() == "is_initialized") {
+    printer->Print(
+        variables_,
+        "// TODO: b/336400327 - remove this hack; we should access properties\n"
+        "$kt_deprecation$public var $kt_name$: $kt_type$\n"
+        "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
+        "  get() = $kt_dsl_builder$.get${$$kt_capitalized_name$$}$()\n"
+        "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
+        "  set(value) {\n"
+        "    $kt_dsl_builder$.${$set$kt_capitalized_name$$}$(value)\n"
+        "  }\n");
+  } else {
+    printer->Print(variables_,
+                   "$kt_deprecation$public var $kt_name$: $kt_type$\n"
+                   "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
+                   "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
+                   "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
+                   "  set(value) {\n"
+                   "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
+                   "  }\n");
+  }
 
   WriteFieldAccessorDocComment(printer, descriptor_, CLEARER,
                                context_->options(),
@@ -718,7 +731,7 @@ void RepeatedImmutablePrimitiveFieldLiteGenerator::GenerateKotlinDslMembers(
                  "<$kt_type$, ${$$kt_capitalized_name$Proxy$}$>\n"
                  "  @kotlin.jvm.JvmSynthetic\n"
                  "  get() = com.google.protobuf.kotlin.DslList(\n"
-                 "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+                 "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
                  "  )\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, LIST_ADDER,
diff --git a/src/google/protobuf/compiler/java/lite/string_field.cc b/src/google/protobuf/compiler/java/lite/string_field.cc
index 833f415585..5e926422bc 100644
--- a/src/google/protobuf/compiler/java/lite/string_field.cc
+++ b/src/google/protobuf/compiler/java/lite/string_field.cc
@@ -22,6 +22,7 @@
 #include "google/protobuf/compiler/java/doc_comment.h"
 #include "google/protobuf/compiler/java/field_common.h"
 #include "google/protobuf/compiler/java/helpers.h"
+#include "google/protobuf/compiler/java/internal_helpers.h"
 #include "google/protobuf/compiler/java/name_resolver.h"
 #include "google/protobuf/wire_format.h"
 
@@ -336,10 +337,10 @@ void ImmutableStringFieldLiteGenerator::GenerateKotlinDslMembers(
   printer->Print(variables_,
                  "$kt_deprecation$public var $kt_name$: kotlin.String\n"
                  "  @JvmName(\"${$get$kt_capitalized_name$$}$\")\n"
-                 "  get() = $kt_dsl_builder$.${$get$capitalized_name$$}$()\n"
+                 "  get() = $kt_dsl_builder$.${$$kt_safe_name$$}$\n"
                  "  @JvmName(\"${$set$kt_capitalized_name$$}$\")\n"
                  "  set(value) {\n"
-                 "    $kt_dsl_builder$.${$set$capitalized_name$$}$(value)\n"
+                 "    $kt_dsl_builder$.${$$kt_safe_name$$}$ = value\n"
                  "  }\n");
 
   WriteFieldAccessorDocComment(printer, descriptor_, CLEARER,
@@ -825,7 +826,7 @@ void RepeatedImmutableStringFieldLiteGenerator::GenerateKotlinDslMembers(
       "@kotlin.OptIn"
       "(com.google.protobuf.kotlin.OnlyForUseByGeneratedProtoCode::class)\n"
       "  get() = com.google.protobuf.kotlin.DslList(\n"
-      "    $kt_dsl_builder$.${$get$capitalized_name$List$}$()\n"
+      "    $kt_dsl_builder$.${$$kt_property_name$List$}$\n"
       "  )\n");
 
   // List<String>.add(String)
diff --git a/src/google/protobuf/compiler/java/names.cc b/src/google/protobuf/compiler/java/names.cc
index 2c47db1942..e1381c78ca 100644
--- a/src/google/protobuf/compiler/java/names.cc
+++ b/src/google/protobuf/compiler/java/names.cc
@@ -39,16 +39,17 @@ const char* DefaultPackage(Options options) {
 bool IsReservedName(absl::string_view name) {
   static const auto& kReservedNames =
       *new absl::flat_hash_set<absl::string_view>({
-          "abstract",   "assert",       "boolean",   "break",      "byte",
-          "case",       "catch",        "char",      "class",      "const",
-          "continue",   "default",      "do",        "double",     "else",
-          "enum",       "extends",      "final",     "finally",    "float",
-          "for",        "goto",         "if",        "implements", "import",
-          "instanceof", "int",          "interface", "long",       "native",
-          "new",        "package",      "private",   "protected",  "public",
-          "return",     "short",        "static",    "strictfp",   "super",
-          "switch",     "synchronized", "this",      "throw",      "throws",
-          "transient",  "try",          "void",      "volatile",   "while",
+          "abstract", "assert",     "boolean",  "break",     "byte",
+          "case",     "catch",      "char",     "class",     "const",
+          "continue", "default",    "do",       "double",    "else",
+          "enum",     "extends",    "false",    "final",     "finally",
+          "float",    "for",        "goto",     "if",        "implements",
+          "import",   "instanceof", "int",      "interface", "java",
+          "long",     "native",     "new",      "null",      "package",
+          "private",  "protected",  "public",   "return",    "short",
+          "static",   "strictfp",   "super",    "switch",    "synchronized",
+          "this",     "throw",      "throws",   "transient", "true",
+          "try",      "void",       "volatile", "while",
       });
   return kReservedNames.contains(name);
 }
@@ -140,6 +141,14 @@ std::string FileJavaPackage(const FileDescriptor* file, Options options) {
   return FileJavaPackage(file, true /* immutable */, options);
 }
 
+std::string JavaPackageDirectory(const FileDescriptor* file) {
+  return JavaPackageToDir(FileJavaPackage(file));
+}
+
+std::string FileClassName(const FileDescriptor* file) {
+  return FileClassName(file, /*immutable=*/true);
+}
+
 std::string CapitalizedFieldName(const FieldDescriptor* field) {
   return UnderscoresToCamelCase(FieldName(field), true);
 }
diff --git a/src/google/protobuf/compiler/java/names.h b/src/google/protobuf/compiler/java/names.h
index d6402fc5d3..c2eb34cb37 100644
--- a/src/google/protobuf/compiler/java/names.h
+++ b/src/google/protobuf/compiler/java/names.h
@@ -72,6 +72,20 @@ std::string ClassName(const ServiceDescriptor* descriptor);
 std::string FileJavaPackage(const FileDescriptor* descriptor,
                             Options options = {});
 
+// Requires:
+//   descriptor != NULL
+//
+// Returns:
+//   Java package directory.
+std::string JavaPackageDirectory(const FileDescriptor* file);
+
+// Requires:
+//   descriptor != NULL
+//
+// Returns:
+//   The unqualified Java class name.
+std::string FileClassName(const FileDescriptor* file);
+
 // Requires:
 //   descriptor != NULL
 // Returns:
diff --git a/src/google/protobuf/compiler/java/options.h b/src/google/protobuf/compiler/java/options.h
index f10b699c68..fbf116bdc6 100644
--- a/src/google/protobuf/compiler/java/options.h
+++ b/src/google/protobuf/compiler/java/options.h
@@ -10,7 +10,7 @@
 
 #include <string>
 
-#include "google/protobuf/port_def.inc"
+#include "google/protobuf/port.h"
 
 namespace google {
 namespace protobuf {
@@ -34,7 +34,7 @@ struct Options {
   // When set, the protoc will generate the current files and all the transitive
   // dependencies as lite runtime.
   bool enforce_lite;
-  bool opensource_runtime = PROTO2_IS_OSS;
+  bool opensource_runtime = google::protobuf::internal::IsOss();
   // If true, we should build .meta files and emit @Generated annotations into
   // generated code.
   bool annotate_code;
@@ -53,5 +53,4 @@ struct Options {
 }  // namespace protobuf
 }  // namespace google
 
-#include "google/protobuf/port_undef.inc"
 #endif  // GOOGLE_PROTOBUF_COMPILER_JAVA_OPTIONS_H__
diff --git a/src/google/protobuf/compiler/objectivec/BUILD.bazel b/src/google/protobuf/compiler/objectivec/BUILD.bazel
index b608b0b0f5..3152976102 100644
--- a/src/google/protobuf/compiler/objectivec/BUILD.bazel
+++ b/src/google/protobuf/compiler/objectivec/BUILD.bazel
@@ -73,7 +73,7 @@ cc_library(
         "message_field.cc",
         "oneof.cc",
         "primitive_field.cc",
-        "text_format_decode_data.cc",
+        "tf_decode_data.cc",
     ],
     hdrs = [
         "enum.h",
@@ -90,7 +90,7 @@ cc_library(
         "oneof.h",
         "options.h",
         "primitive_field.h",
-        "text_format_decode_data.h",
+        "tf_decode_data.h",
     ],
     copts = COPTS,
     strip_include_prefix = "/src",
diff --git a/src/google/protobuf/compiler/objectivec/enum.cc b/src/google/protobuf/compiler/objectivec/enum.cc
index fae53a2606..c8bfcbc3df 100644
--- a/src/google/protobuf/compiler/objectivec/enum.cc
+++ b/src/google/protobuf/compiler/objectivec/enum.cc
@@ -17,7 +17,7 @@
 #include "google/protobuf/compiler/objectivec/helpers.h"
 #include "google/protobuf/compiler/objectivec/names.h"
 #include "google/protobuf/compiler/objectivec/options.h"
-#include "google/protobuf/compiler/objectivec/text_format_decode_data.h"
+#include "google/protobuf/compiler/objectivec/tf_decode_data.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/io/printer.h"
 
diff --git a/src/google/protobuf/compiler/objectivec/message.cc b/src/google/protobuf/compiler/objectivec/message.cc
index c3f2ef6d3a..cde92f60d0 100644
--- a/src/google/protobuf/compiler/objectivec/message.cc
+++ b/src/google/protobuf/compiler/objectivec/message.cc
@@ -26,7 +26,7 @@
 #include "google/protobuf/compiler/objectivec/names.h"
 #include "google/protobuf/compiler/objectivec/oneof.h"
 #include "google/protobuf/compiler/objectivec/options.h"
-#include "google/protobuf/compiler/objectivec/text_format_decode_data.h"
+#include "google/protobuf/compiler/objectivec/tf_decode_data.h"
 #include "google/protobuf/descriptor.h"
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/io/printer.h"
diff --git a/src/google/protobuf/compiler/objectivec/text_format_decode_data_unittest.cc b/src/google/protobuf/compiler/objectivec/text_format_decode_data_unittest.cc
index c373128163..d730948934 100644
--- a/src/google/protobuf/compiler/objectivec/text_format_decode_data_unittest.cc
+++ b/src/google/protobuf/compiler/objectivec/text_format_decode_data_unittest.cc
@@ -5,12 +5,12 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#include "google/protobuf/compiler/objectivec/text_format_decode_data.h"
 
 #include <cstdint>
 #include <string>
 
 #include <gtest/gtest.h>
+#include "google/protobuf/compiler/objectivec/tf_decode_data.h"
 
 // Must be included last
 #include "google/protobuf/port_def.inc"
diff --git a/src/google/protobuf/compiler/objectivec/text_format_decode_data.cc b/src/google/protobuf/compiler/objectivec/tf_decode_data.cc
similarity index 98%
rename from src/google/protobuf/compiler/objectivec/text_format_decode_data.cc
rename to src/google/protobuf/compiler/objectivec/tf_decode_data.cc
index fe48f8d157..8eade5d17a 100644
--- a/src/google/protobuf/compiler/objectivec/text_format_decode_data.cc
+++ b/src/google/protobuf/compiler/objectivec/tf_decode_data.cc
@@ -5,7 +5,7 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#include "google/protobuf/compiler/objectivec/text_format_decode_data.h"
+#include "google/protobuf/compiler/objectivec/tf_decode_data.h"
 
 #include <cstdint>
 #include <sstream>
diff --git a/src/google/protobuf/compiler/objectivec/text_format_decode_data.h b/src/google/protobuf/compiler/objectivec/tf_decode_data.h
similarity index 88%
rename from src/google/protobuf/compiler/objectivec/text_format_decode_data.h
rename to src/google/protobuf/compiler/objectivec/tf_decode_data.h
index f562d32542..1e7932afa2 100644
--- a/src/google/protobuf/compiler/objectivec/text_format_decode_data.h
+++ b/src/google/protobuf/compiler/objectivec/tf_decode_data.h
@@ -5,8 +5,8 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#ifndef GOOGLE_PROTOBUF_COMPILER_OBJECTIVEC_TEXT_FORMAT_DECODE_DATA_H__
-#define GOOGLE_PROTOBUF_COMPILER_OBJECTIVEC_TEXT_FORMAT_DECODE_DATA_H__
+#ifndef GOOGLE_PROTOBUF_COMPILER_OBJECTIVEC_TF_DECODE_DATA_H__
+#define GOOGLE_PROTOBUF_COMPILER_OBJECTIVEC_TF_DECODE_DATA_H__
 
 #include <cstddef>
 #include <cstdint>
@@ -55,4 +55,4 @@ class PROTOC_EXPORT TextFormatDecodeData {
 
 #include "google/protobuf/port_undef.inc"
 
-#endif  // GOOGLE_PROTOBUF_COMPILER_OBJECTIVEC_TEXT_FORMAT_DECODE_DATA_H__
+#endif  // GOOGLE_PROTOBUF_COMPILER_OBJECTIVEC_TF_DECODE_DATA_H__
diff --git a/src/google/protobuf/compiler/parser.cc b/src/google/protobuf/compiler/parser.cc
index f6f7d1d509..c2595fe74a 100644
--- a/src/google/protobuf/compiler/parser.cc
+++ b/src/google/protobuf/compiler/parser.cc
@@ -38,6 +38,7 @@
 #include "google/protobuf/descriptor.pb.h"
 #include "google/protobuf/io/strtod.h"
 #include "google/protobuf/io/tokenizer.h"
+#include "google/protobuf/message_lite.h"
 #include "google/protobuf/port.h"
 #include "google/protobuf/wire_format.h"
 
@@ -49,8 +50,6 @@ namespace protobuf {
 namespace compiler {
 namespace {
 
-using ::google::protobuf::internal::DownCast;
-
 using TypeNameMap =
     absl::flat_hash_map<absl::string_view, FieldDescriptorProto::Type>;
 
@@ -1566,8 +1565,9 @@ bool Parser::ParseOption(Message* options,
   }
 
   UninterpretedOption* uninterpreted_option =
-      DownCast<UninterpretedOption*>(options->GetReflection()->AddMessage(
-          options, uninterpreted_option_field));
+      DownCastToGenerated<UninterpretedOption>(
+          options->GetReflection()->AddMessage(options,
+                                               uninterpreted_option_field));
 
   // Parse dot-separated name.
   {
@@ -1623,12 +1623,21 @@ bool Parser::ParseOption(Message* options,
       case io::Tokenizer::TYPE_IDENTIFIER: {
         value_location.AddPath(
             UninterpretedOption::kIdentifierValueFieldNumber);
-        if (is_negative) {
-          RecordError("Invalid '-' symbol before identifier.");
-          return false;
-        }
         std::string value;
         DO(ConsumeIdentifier(&value, "Expected identifier."));
+        if (is_negative) {
+          if (value == "inf") {
+            uninterpreted_option->set_double_value(
+                -std::numeric_limits<double>::infinity());
+          } else if (value == "nan") {
+            uninterpreted_option->set_double_value(
+                std::numeric_limits<double>::quiet_NaN());
+          } else {
+            RecordError("Identifier after '-' symbol must be inf or nan.");
+            return false;
+          }
+          break;
+        }
         uninterpreted_option->set_identifier_value(value);
         break;
       }
diff --git a/src/google/protobuf/compiler/parser_unittest.cc b/src/google/protobuf/compiler/parser_unittest.cc
index 46c1e2e5ff..f9b8f32317 100644
--- a/src/google/protobuf/compiler/parser_unittest.cc
+++ b/src/google/protobuf/compiler/parser_unittest.cc
@@ -12,6 +12,7 @@
 #include "google/protobuf/compiler/parser.h"
 
 #include <algorithm>
+#include <cmath>
 #include <memory>
 #include <string>
 #include <utility>
@@ -460,6 +461,7 @@ TEST_F(ParseMessageTest, FieldDefaults) {
       "  required double foo = 1 [default= inf ];\n"
       "  required double foo = 1 [default=-inf ];\n"
       "  required double foo = 1 [default= nan ];\n"
+      "  required double foo = 1 [default= -nan ];\n"
       "  required string foo = 1 [default='13\\001'];\n"
       "  required string foo = 1 [default='a' \"b\" \n \"c\"];\n"
       "  required bytes  foo = 1 [default='14\\002'];\n"
@@ -509,6 +511,8 @@ TEST_F(ParseMessageTest, FieldDefaults) {
       " }"
       "  field { type:TYPE_DOUBLE  default_value:\"nan\"       " ETC
       " }"
+      "  field { type:TYPE_DOUBLE  default_value:\"-nan\"      " ETC
+      " }"
       "  field { type:TYPE_STRING  default_value:\"13\\001\"   " ETC
       " }"
       "  field { type:TYPE_STRING  default_value:\"abc\"       " ETC
@@ -658,6 +662,65 @@ TEST_F(ParseMessageTest, FieldOptionsSupportLargeDecimalLiteral) {
       "}");
 }
 
+TEST_F(ParseMessageTest, FieldOptionsSupportInfAndNan) {
+  ExpectParsesTo(
+      "import \"google/protobuf/descriptor.proto\";\n"
+      "extend google.protobuf.FieldOptions {\n"
+      "  optional double f = 10101;\n"
+      "}\n"
+      "message TestMessage {\n"
+      "  optional double a = 1 [(f) = inf];\n"
+      "  optional double b = 2 [(f) = -inf];\n"
+      "  optional double c = 3 [(f) = nan];\n"
+      "  optional double d = 4 [(f) = -nan];\n"
+      "}\n",
+
+      "dependency: \"google/protobuf/descriptor.proto\""
+      "extension {"
+      "  name: \"f\" label: LABEL_OPTIONAL type: TYPE_DOUBLE number: 10101"
+      "  extendee: \"google.protobuf.FieldOptions\""
+      "}"
+      "message_type {"
+      "  name: \"TestMessage\""
+      "  field {"
+      "    name: \"a\" label: LABEL_OPTIONAL type: TYPE_DOUBLE number: 1"
+      "    options{"
+      "      uninterpreted_option{"
+      "        name{ name_part: \"f\" is_extension: true }"
+      "        identifier_value: \"inf\""
+      "      }"
+      "    }"
+      "  }"
+      "  field {"
+      "    name: \"b\" label: LABEL_OPTIONAL type: TYPE_DOUBLE number: 2"
+      "    options{"
+      "      uninterpreted_option{"
+      "        name{ name_part: \"f\" is_extension: true }"
+      "        double_value: -infinity"
+      "      }"
+      "    }"
+      "  }"
+      "  field {"
+      "    name: \"c\" label: LABEL_OPTIONAL type: TYPE_DOUBLE number: 3"
+      "    options{"
+      "      uninterpreted_option{"
+      "        name{ name_part: \"f\" is_extension: true }"
+      "        identifier_value: \"nan\""
+      "      }"
+      "    }"
+      "  }"
+      "  field {"
+      "    name: \"d\" label: LABEL_OPTIONAL type: TYPE_DOUBLE number: 4"
+      "    options{"
+      "      uninterpreted_option{"
+      "        name{ name_part: \"f\" is_extension: true }"
+      "        double_value: nan"
+      "      }"
+      "    }"
+      "  }"
+      "}");
+}
+
 TEST_F(ParseMessageTest, Oneof) {
   ExpectParsesTo(
       "message TestMessage {\n"
@@ -1396,6 +1459,48 @@ TEST_F(ParseMiscTest, ParseFileOptions) {
       "}");
 }
 
+TEST_F(ParseMiscTest, InterpretedOptions) {
+  // Since we're importing the generated code from parsing/compiling
+  // unittest_custom_options.proto, we can just look at the option
+  // values from that file's descriptor in the generated code.
+  {
+    const MessageOptions& options =
+        protobuf_unittest::SettingRealsFromInf ::descriptor()->options();
+    float float_val = options.GetExtension(protobuf_unittest::float_opt);
+    ASSERT_TRUE(std::isinf(float_val));
+    ASSERT_GT(float_val, 0);
+    double double_val = options.GetExtension(protobuf_unittest::double_opt);
+    ASSERT_TRUE(std::isinf(double_val));
+    ASSERT_GT(double_val, 0);
+  }
+  {
+    const MessageOptions& options =
+        protobuf_unittest::SettingRealsFromNegativeInf ::descriptor()->options();
+    float float_val = options.GetExtension(protobuf_unittest::float_opt);
+    ASSERT_TRUE(std::isinf(float_val));
+    ASSERT_LT(float_val, 0);
+    double double_val = options.GetExtension(protobuf_unittest::double_opt);
+    ASSERT_TRUE(std::isinf(double_val));
+    ASSERT_LT(double_val, 0);
+  }
+  {
+    const MessageOptions& options =
+        protobuf_unittest::SettingRealsFromNan ::descriptor()->options();
+    float float_val = options.GetExtension(protobuf_unittest::float_opt);
+    ASSERT_TRUE(std::isnan(float_val));
+    double double_val = options.GetExtension(protobuf_unittest::double_opt);
+    ASSERT_TRUE(std::isnan(double_val));
+  }
+  {
+    const MessageOptions& options =
+        protobuf_unittest::SettingRealsFromNegativeNan ::descriptor()->options();
+    float float_val = options.GetExtension(protobuf_unittest::float_opt);
+    ASSERT_TRUE(std::isnan(float_val));
+    double double_val = options.GetExtension(protobuf_unittest::double_opt);
+    ASSERT_TRUE(std::isnan(double_val));
+  }
+}
+
 // ===================================================================
 // Error tests
 //
diff --git a/src/google/protobuf/compiler/php/php_generator.h b/src/google/protobuf/compiler/php/php_generator.h
index a270b2004f..10d3f0e09c 100644
--- a/src/google/protobuf/compiler/php/php_generator.h
+++ b/src/google/protobuf/compiler/php/php_generator.h
@@ -37,7 +37,13 @@ class PROTOC_EXPORT Generator : public CodeGenerator {
                    std::string* error) const override;
 
   uint64_t GetSupportedFeatures() const override {
-    return FEATURE_PROTO3_OPTIONAL;
+    return Feature::FEATURE_PROTO3_OPTIONAL;
+  }
+
+  Edition GetMinimumEdition() const override { return Edition::EDITION_PROTO2; }
+  Edition GetMaximumEdition() const override { return Edition::EDITION_2023; }
+  std::vector<const FieldDescriptor*> GetFeatureExtensions() const override {
+    return {};
   }
 
  private:
diff --git a/src/google/protobuf/compiler/plugin.pb.cc b/src/google/protobuf/compiler/plugin.pb.cc
index 61d8c33097..b10c89f7f9 100644
--- a/src/google/protobuf/compiler/plugin.pb.cc
+++ b/src/google/protobuf/compiler/plugin.pb.cc
@@ -501,14 +501,15 @@ PROTOBUF_NOINLINE void Version::Clear() {
 }
 
 ::size_t Version::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.Version)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.Version)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000000fu) {
     // optional string suffix = 4;
@@ -516,25 +517,21 @@ PROTOBUF_NOINLINE void Version::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_suffix());
     }
-
     // optional int32 major = 1;
     if (cached_has_bits & 0x00000002u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_major());
     }
-
     // optional int32 minor = 2;
     if (cached_has_bits & 0x00000004u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_minor());
     }
-
     // optional int32 patch = 3;
     if (cached_has_bits & 0x00000008u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_patch());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -838,29 +835,38 @@ PROTOBUF_NOINLINE void CodeGeneratorRequest::Clear() {
 }
 
 ::size_t CodeGeneratorRequest::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.CodeGeneratorRequest)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.CodeGeneratorRequest)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated string file_to_generate = 1;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_file_to_generate().size());
-  for (int i = 0, n = _internal_file_to_generate().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_file_to_generate().Get(i));
-  }
-  // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
-  total_size += 1UL * this->_internal_proto_file_size();
-  for (const auto& msg : this->_internal_proto_file()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.FileDescriptorProto source_file_descriptors = 17;
-  total_size += 2UL * this->_internal_source_file_descriptors_size();
-  for (const auto& msg : this->_internal_source_file_descriptors()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated string file_to_generate = 1;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_file_to_generate().size());
+      for (int i = 0, n = _internal_file_to_generate().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_file_to_generate().Get(i));
+      }
+    }
+    // repeated .google.protobuf.FileDescriptorProto proto_file = 15;
+     {
+      total_size += 1UL * this->_internal_proto_file_size();
+      for (const auto& msg : this->_internal_proto_file()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.FileDescriptorProto source_file_descriptors = 17;
+     {
+      total_size += 2UL * this->_internal_source_file_descriptors_size();
+      for (const auto& msg : this->_internal_source_file_descriptors()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -869,13 +875,11 @@ PROTOBUF_NOINLINE void CodeGeneratorRequest::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_parameter());
     }
-
     // optional .google.protobuf.compiler.Version compiler_version = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.compiler_version_);
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -1170,14 +1174,15 @@ PROTOBUF_NOINLINE void CodeGeneratorResponse_File::Clear() {
 }
 
 ::size_t CodeGeneratorResponse_File::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.CodeGeneratorResponse.File)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.CodeGeneratorResponse.File)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000000fu) {
     // optional string name = 1;
@@ -1185,25 +1190,21 @@ PROTOBUF_NOINLINE void CodeGeneratorResponse_File::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional string insertion_point = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_insertion_point());
     }
-
     // optional string content = 15;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_content());
     }
-
     // optional .google.protobuf.GeneratedCodeInfo generated_code_info = 16;
     if (cached_has_bits & 0x00000008u) {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.generated_code_info_);
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -1498,18 +1499,23 @@ PROTOBUF_NOINLINE void CodeGeneratorResponse::Clear() {
 }
 
 ::size_t CodeGeneratorResponse::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.CodeGeneratorResponse)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.compiler.CodeGeneratorResponse)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
-  total_size += 1UL * this->_internal_file_size();
-  for (const auto& msg : this->_internal_file()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.compiler.CodeGeneratorResponse.File file = 15;
+     {
+      total_size += 1UL * this->_internal_file_size();
+      for (const auto& msg : this->_internal_file()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000000fu) {
@@ -1518,25 +1524,21 @@ PROTOBUF_NOINLINE void CodeGeneratorResponse::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_error());
     }
-
     // optional uint64 supported_features = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += ::_pbi::WireFormatLite::UInt64SizePlusOne(
           this->_internal_supported_features());
     }
-
     // optional int32 minimum_edition = 3;
     if (cached_has_bits & 0x00000004u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_minimum_edition());
     }
-
     // optional int32 maximum_edition = 4;
     if (cached_has_bits & 0x00000008u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_maximum_edition());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
diff --git a/src/google/protobuf/compiler/rust/BUILD.bazel b/src/google/protobuf/compiler/rust/BUILD.bazel
index 6b6f98754c..5ff8f510ac 100644
--- a/src/google/protobuf/compiler/rust/BUILD.bazel
+++ b/src/google/protobuf/compiler/rust/BUILD.bazel
@@ -82,7 +82,6 @@ cc_library(
     copts = COPTS,
     strip_include_prefix = "/src",
     deps = [
-        ":accessors",
         ":context",
         ":enum",
         ":naming",
@@ -90,6 +89,7 @@ cc_library(
         "//src/google/protobuf",
         "//src/google/protobuf/compiler/cpp:names",
         "//src/google/protobuf/compiler/cpp:names_internal",
+        "//src/google/protobuf/compiler/rust/accessors",
         "//upb_generator:mangle",
         "@com_google_absl//absl/log:absl_check",
         "@com_google_absl//absl/log:absl_log",
@@ -98,46 +98,15 @@ cc_library(
     ],
 )
 
-cc_library(
-    name = "accessors",
-    srcs = [
-        "accessors/accessor_case.cc",
-        "accessors/accessors.cc",
-        "accessors/map.cc",
-        "accessors/repeated_field.cc",
-        "accessors/singular_message.cc",
-        "accessors/singular_scalar.cc",
-        "accessors/singular_string.cc",
-        "accessors/unsupported_field.cc",
-    ],
-    hdrs = [
-        "accessors/accessor_case.h",
-        "accessors/accessor_generator.h",
-        "accessors/accessors.h",
-    ],
-    copts = COPTS,
-    strip_include_prefix = "/src",
-    deps = [
-        ":context",
-        ":helpers",
-        ":naming",
-        ":rust_field_type",
-        "//src/google/protobuf",
-        "//src/google/protobuf/compiler/cpp:names_internal",
-        "//src/google/protobuf/io:tokenizer",
-        "@com_google_absl//absl/log:absl_check",
-        "@com_google_absl//absl/log:absl_log",
-        "@com_google_absl//absl/strings",
-        "@com_google_absl//absl/strings:str_format",
-    ],
-)
-
 cc_library(
     name = "context",
     srcs = ["context.cc"],
     hdrs = ["context.h"],
     copts = COPTS,
     strip_include_prefix = "/src",
+    visibility = [
+        "//src/google/protobuf/compiler/rust:__subpackages__",
+    ],
     deps = [
         "//src/google/protobuf",
         "//src/google/protobuf/compiler:code_generator",
@@ -195,6 +164,9 @@ cc_library(
     ],
     copts = COPTS,
     strip_include_prefix = "/src",
+    visibility = [
+        "//src/google/protobuf/compiler/rust:__subpackages__",
+    ],
     deps = [
         ":context",
         ":rust_field_type",
@@ -216,13 +188,13 @@ cc_library(
     copts = COPTS,
     strip_include_prefix = "/src",
     deps = [
-        ":accessors",
         ":context",
         ":naming",
         ":rust_field_type",
         "//src/google/protobuf",
         "//src/google/protobuf/compiler/cpp:names",
         "//src/google/protobuf/compiler/cpp:names_internal",
+        "//src/google/protobuf/compiler/rust/accessors",
         "@com_google_absl//absl/log:absl_log",
         "@com_google_absl//absl/strings",
     ],
@@ -250,29 +222,14 @@ cc_test(
     ],
 )
 
-cc_library(
-    name = "helpers",
-    srcs = ["accessors/helpers.cc"],
-    hdrs = ["accessors/helpers.h"],
-    strip_include_prefix = "/src",
-    deps = [
-        ":context",
-        ":naming",
-        ":rust_field_type",
-        "//src/google/protobuf",
-        "//src/google/protobuf/io:tokenizer",
-        "@com_google_absl//absl/log:absl_check",
-        "@com_google_absl//absl/log:absl_log",
-        "@com_google_absl//absl/strings",
-        "@com_google_absl//absl/strings:str_format",
-    ],
-)
-
 cc_library(
     name = "rust_field_type",
     srcs = ["rust_field_type.cc"],
     hdrs = ["rust_field_type.h"],
     strip_include_prefix = "/src",
+    visibility = [
+        "//src/google/protobuf/compiler/rust:__subpackages__",
+    ],
     deps = [
         "//src/google/protobuf",
         "@com_google_absl//absl/log:absl_log",
diff --git a/src/google/protobuf/compiler/rust/accessors/BUILD.bazel b/src/google/protobuf/compiler/rust/accessors/BUILD.bazel
new file mode 100644
index 0000000000..d7bf99e34e
--- /dev/null
+++ b/src/google/protobuf/compiler/rust/accessors/BUILD.bazel
@@ -0,0 +1,45 @@
+################################################################################
+# Protocol Buffers Compiler - Generation of accessors for individual fields.
+################################################################################
+
+load("@rules_cc//cc:defs.bzl", "cc_library")
+load("//build_defs:cpp_opts.bzl", "COPTS")
+
+cc_library(
+    name = "accessors",
+    srcs = [
+        "accessor_case.cc",
+        "accessors.cc",
+        "default_value.cc",
+        "map.cc",
+        "repeated_field.cc",
+        "singular_message.cc",
+        "singular_scalar.cc",
+        "singular_string.cc",
+        "unsupported_field.cc",
+    ],
+    hdrs = [
+        "accessor_case.h",
+        "accessors.h",
+        "default_value.h",
+        "generator.h",
+    ],
+    copts = COPTS,
+    strip_include_prefix = "/src",
+    visibility = [
+        "//pkg:__pkg__",
+        "//src/google/protobuf/compiler:__subpackages__",
+    ],
+    deps = [
+        "//src/google/protobuf",
+        "//src/google/protobuf/compiler/cpp:names_internal",
+        "//src/google/protobuf/compiler/rust:context",
+        "//src/google/protobuf/compiler/rust:naming",
+        "//src/google/protobuf/compiler/rust:rust_field_type",
+        "//src/google/protobuf/io:tokenizer",
+        "@com_google_absl//absl/log:absl_check",
+        "@com_google_absl//absl/log:absl_log",
+        "@com_google_absl//absl/strings",
+        "@com_google_absl//absl/strings:str_format",
+    ],
+)
diff --git a/src/google/protobuf/compiler/rust/accessors/accessors.cc b/src/google/protobuf/compiler/rust/accessors/accessors.cc
index 9aa654577f..30984c9dcf 100644
--- a/src/google/protobuf/compiler/rust/accessors/accessors.cc
+++ b/src/google/protobuf/compiler/rust/accessors/accessors.cc
@@ -11,7 +11,7 @@
 
 #include "absl/log/absl_log.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/compiler/rust/rust_field_type.h"
 #include "google/protobuf/descriptor.h"
diff --git a/src/google/protobuf/compiler/rust/accessors/helpers.cc b/src/google/protobuf/compiler/rust/accessors/default_value.cc
similarity index 98%
rename from src/google/protobuf/compiler/rust/accessors/helpers.cc
rename to src/google/protobuf/compiler/rust/accessors/default_value.cc
index 71c6b280f6..27594b3c1f 100644
--- a/src/google/protobuf/compiler/rust/accessors/helpers.cc
+++ b/src/google/protobuf/compiler/rust/accessors/default_value.cc
@@ -5,7 +5,7 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-#include "google/protobuf/compiler/rust/accessors/helpers.h"
+#include "google/protobuf/compiler/rust/accessors/default_value.h"
 
 #include <cmath>
 #include <limits>
diff --git a/src/google/protobuf/compiler/rust/accessors/helpers.h b/src/google/protobuf/compiler/rust/accessors/default_value.h
similarity index 100%
rename from src/google/protobuf/compiler/rust/accessors/helpers.h
rename to src/google/protobuf/compiler/rust/accessors/default_value.h
diff --git a/src/google/protobuf/compiler/rust/accessors/accessor_generator.h b/src/google/protobuf/compiler/rust/accessors/generator.h
similarity index 100%
rename from src/google/protobuf/compiler/rust/accessors/accessor_generator.h
rename to src/google/protobuf/compiler/rust/accessors/generator.h
diff --git a/src/google/protobuf/compiler/rust/accessors/map.cc b/src/google/protobuf/compiler/rust/accessors/map.cc
index ee0d089784..e38f03da5b 100644
--- a/src/google/protobuf/compiler/rust/accessors/map.cc
+++ b/src/google/protobuf/compiler/rust/accessors/map.cc
@@ -9,7 +9,7 @@
 
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/compiler/rust/naming.h"
 #include "google/protobuf/descriptor.h"
@@ -39,8 +39,10 @@ void Map::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                     AccessorCase accessor_case) const {
   auto& key_type = *field.message_type()->map_key();
   auto& value_type = *field.message_type()->map_value();
+  std::string field_name = FieldNameWithCollisionAvoidance(field);
 
-  ctx.Emit({{"field", RsSafeName(field.name())},
+  ctx.Emit({{"field", RsSafeName(field_name)},
+            {"raw_field_name", field_name},  // Never r# prefixed
             {"Key", RsTypePath(ctx, key_type)},
             {"Value", RsTypePath(ctx, value_type)},
             {"view_lifetime", ViewLifetime(accessor_case)},
@@ -98,10 +100,23 @@ void Map::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                       unsafe { $pb$::MapMut::from_inner($pbi$::Private, inner) }
                     })rs");
                }
+             }},
+            {"setter",
+             [&] {
+               if (accessor_case == AccessorCase::VIEW) {
+                 return;
+               }
+               ctx.Emit({}, R"rs(
+                pub fn set_$raw_field_name$(&mut self, src: $pb$::MapView<'_, $Key$, $Value$>) {
+                  // TODO: Implement IntoProxied and avoid copying.
+                  self.$field$_mut().copy_from(src);
+                }
+              )rs");
              }}},
            R"rs(
     $getter$
     $getter_mut$
+    $setter$
     )rs");
 }
 
diff --git a/src/google/protobuf/compiler/rust/accessors/repeated_field.cc b/src/google/protobuf/compiler/rust/accessors/repeated_field.cc
index c48b437847..8f5ee25d45 100644
--- a/src/google/protobuf/compiler/rust/accessors/repeated_field.cc
+++ b/src/google/protobuf/compiler/rust/accessors/repeated_field.cc
@@ -10,7 +10,7 @@
 #include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/compiler/rust/naming.h"
 #include "google/protobuf/descriptor.h"
@@ -22,16 +22,20 @@ namespace rust {
 
 void RepeatedField::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                               AccessorCase accessor_case) const {
-  ctx.Emit({{"field", RsSafeName(field.name())},
-            {"RsType", RsTypePath(ctx, field)},
-            {"view_lifetime", ViewLifetime(accessor_case)},
-            {"view_self", ViewReceiver(accessor_case)},
-            {"getter_thunk", ThunkName(ctx, field, "get")},
-            {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
-            {"getter",
-             [&] {
-               if (ctx.is_upb()) {
-                 ctx.Emit({}, R"rs(
+  std::string field_name = FieldNameWithCollisionAvoidance(field);
+  ctx.Emit(
+      {
+          {"field", RsSafeName(field_name)},
+          {"raw_field_name", field_name},  // Never r# prefixed
+          {"RsType", RsTypePath(ctx, field)},
+          {"view_lifetime", ViewLifetime(accessor_case)},
+          {"view_self", ViewReceiver(accessor_case)},
+          {"getter_thunk", ThunkName(ctx, field, "get")},
+          {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
+          {"getter",
+           [&] {
+             if (ctx.is_upb()) {
+               ctx.Emit({}, R"rs(
                     pub fn $field$($view_self$) -> $pb$::RepeatedView<$view_lifetime$, $RsType$> {
                       unsafe {
                         $getter_thunk$(
@@ -46,8 +50,8 @@ void RepeatedField::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                         )
                     }
                   )rs");
-               } else {
-                 ctx.Emit({}, R"rs(
+             } else {
+               ctx.Emit({}, R"rs(
                     pub fn $field$($view_self$) -> $pb$::RepeatedView<$view_lifetime$, $RsType$> {
                       unsafe {
                         $pb$::RepeatedView::from_raw(
@@ -57,16 +61,16 @@ void RepeatedField::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                       }
                     }
                   )rs");
-               }
-             }},
-            {"clearer_thunk", ThunkName(ctx, field, "clear")},
-            {"getter_mut",
-             [&] {
-               if (accessor_case == AccessorCase::VIEW) {
-                 return;
-               }
-               if (ctx.is_upb()) {
-                 ctx.Emit({}, R"rs(
+             }
+           }},
+          {"clearer_thunk", ThunkName(ctx, field, "clear")},
+          {"getter_mut",
+           [&] {
+             if (accessor_case == AccessorCase::VIEW) {
+               return;
+             }
+             if (ctx.is_upb()) {
+               ctx.Emit({}, R"rs(
                     pub fn $field$_mut(&mut self) -> $pb$::RepeatedMut<'_, $RsType$> {
                       unsafe {
                         $pb$::RepeatedMut::from_inner(
@@ -84,8 +88,8 @@ void RepeatedField::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                       }
                     }
                   )rs");
-               } else {
-                 ctx.Emit({}, R"rs(
+             } else {
+               ctx.Emit({}, R"rs(
                       pub fn $field$_mut(&mut self) -> $pb$::RepeatedMut<'_, $RsType$> {
                         unsafe {
                           $pb$::RepeatedMut::from_inner(
@@ -98,11 +102,55 @@ void RepeatedField::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                         }
                       }
                     )rs");
-               }
-             }}},
-           R"rs(
+             }
+           }},
+          {"move_setter_thunk", ThunkName(ctx, field, "move_set")},
+          {"setter",
+           [&] {
+             if (accessor_case == AccessorCase::VIEW) {
+               return;
+             }
+             if (ctx.is_upb()) {
+               ctx.Emit({{"field_number", field.number()}}, R"rs(
+                    pub fn set_$raw_field_name$(&mut self, src: impl $pb$::IntoProxied<$pb$::Repeated<$RsType$>>) {
+                      let minitable_field = unsafe {
+                        $pbr$::upb_MiniTable_FindFieldByNumber(
+                          Self::raw_minitable($pbi$::Private),
+                          $field_number$
+                        )
+                      };
+                      let val = src.into($pbi$::Private);
+                      let inner = val.inner($pbi$::Private);
+
+                      self.arena().fuse(inner.arena());
+                      unsafe {
+                          let value_ptr: *const *const std::ffi::c_void =
+                              &(inner.raw().as_ptr() as *const std::ffi::c_void);
+                          $pbr$::upb_Message_SetBaseField(self.raw_msg(),
+                            minitable_field,
+                            value_ptr as *const std::ffi::c_void);
+                      }
+                    }
+                  )rs");
+             } else {
+               ctx.Emit({}, R"rs(
+                      pub fn set_$raw_field_name$(&mut self, src: impl $pb$::IntoProxied<$pb$::Repeated<$RsType$>>) {
+                        // Prevent the memory from being deallocated. The setter
+                        // transfers ownership of the memory to the parent message.
+                        let val = std::mem::ManuallyDrop::new(src.into($pbi$::Private));
+                        unsafe {
+                          $move_setter_thunk$(self.raw_msg(),
+                            val.inner($pbi$::Private).raw());
+                        }
+                      }
+                    )rs");
+             }
+           }},
+      },
+      R"rs(
           $getter$
           $getter_mut$
+          $setter$
         )rs");
 }
 
@@ -110,6 +158,7 @@ void RepeatedField::InExternC(Context& ctx,
                               const FieldDescriptor& field) const {
   ctx.Emit({{"getter_thunk", ThunkName(ctx, field, "get")},
             {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
+            {"move_setter_thunk", ThunkName(ctx, field, "move_set")},
             {"getter",
              [&] {
                if (ctx.is_upb()) {
@@ -129,6 +178,7 @@ void RepeatedField::InExternC(Context& ctx,
                  ctx.Emit(R"rs(
                     fn $getter_mut_thunk$(raw_msg: $pbr$::RawMessage) -> $pbr$::RawRepeatedField;
                     fn $getter_thunk$(raw_msg: $pbr$::RawMessage) -> $pbr$::RawRepeatedField;
+                    fn $move_setter_thunk$(raw_msg: $pbr$::RawMessage, value: $pbr$::RawRepeatedField);
                   )rs");
                }
              }},
@@ -179,6 +229,9 @@ void RepeatedField::InThunkCc(Context& ctx,
             {"clearer_thunk", ThunkName(ctx, field, "clear")},
             {"getter_thunk", ThunkName(ctx, field, "get")},
             {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
+            {"repeated_copy_from_thunk",
+             ThunkName(ctx, field, "repeated_copy_from")},
+            {"move_setter_thunk", ThunkName(ctx, field, "move_set")},
             {"impls",
              [&] {
                ctx.Emit(
@@ -193,6 +246,11 @@ void RepeatedField::InThunkCc(Context& ctx,
                          const $QualifiedMsg$* msg) {
                        return &msg->$field$();
                      }
+                     void $move_setter_thunk$(
+                         $QualifiedMsg$* msg,
+                         $ContainerType$<$ElementType$>* value) {
+                       *msg->mutable_$field$() = std::move(*value);
+                     }
                    )cc");
              }}},
            "$impls$");
diff --git a/src/google/protobuf/compiler/rust/accessors/singular_message.cc b/src/google/protobuf/compiler/rust/accessors/singular_message.cc
index 8f3ea9bfe0..01f44fad36 100644
--- a/src/google/protobuf/compiler/rust/accessors/singular_message.cc
+++ b/src/google/protobuf/compiler/rust/accessors/singular_message.cc
@@ -10,7 +10,7 @@
 #include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/compiler/rust/naming.h"
 #include "google/protobuf/descriptor.h"
@@ -24,15 +24,17 @@ void SingularMessage::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                                 AccessorCase accessor_case) const {
   // fully qualified message name with modules prefixed
   std::string msg_type = RsTypePath(ctx, field);
+  std::string field_name = FieldNameWithCollisionAvoidance(field);
   ctx.Emit({{"msg_type", msg_type},
-            {"field", RsSafeName(field.name())},
-            {"raw_field_name", field.name()},
+            {"field", RsSafeName(field_name)},
+            {"raw_field_name", field_name},
             {"view_lifetime", ViewLifetime(accessor_case)},
             {"view_self", ViewReceiver(accessor_case)},
             {"getter_thunk", ThunkName(ctx, field, "get")},
             {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
             {"clearer_thunk", ThunkName(ctx, field, "clear")},
             {"hazzer_thunk", ThunkName(ctx, field, "has")},
+            {"set_allocated_thunk", ThunkName(ctx, field, "set")},
             {
                 "getter_body",
                 [&] {
@@ -67,39 +69,34 @@ void SingularMessage::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                 }
               )rs");
              }},
-            {"getter_mut",
+            {"getter_mut_body",
              [&] {
-               if (accessor_case == AccessorCase::VIEW) {
-                 return;
-               }
-               ctx.Emit({}, R"rs(
-                  pub fn $raw_field_name$_mut(&mut self) -> $msg_type$Mut<'_> {
-                    self.$raw_field_name$_entry().or_default()
-                  }
+               if (ctx.is_cpp()) {
+                 ctx.Emit({}, R"rs(
+                  let raw_msg = unsafe { $getter_mut_thunk$(self.raw_msg()) };
+                  $msg_type$Mut::from_parent($pbi$::Private,
+                  self.as_mutator_message_ref($pbi$::Private), raw_msg)
+                 )rs");
+               } else {
+                 ctx.Emit({}, R"rs(
+                  let raw_msg = unsafe { 
+                    $getter_mut_thunk$(self.raw_msg(), self.arena().raw())
+                  };
+                  $msg_type$Mut::from_parent($pbi$::Private,
+                    self.as_mutator_message_ref($pbi$::Private), raw_msg)
                 )rs");
+               }
              }},
-            {"private_getter_entry",
+            {"getter_mut",
              [&] {
                if (accessor_case == AccessorCase::VIEW) {
                  return;
                }
+
                ctx.Emit({}, R"rs(
-                fn $raw_field_name$_entry(&mut self)
-                    -> $pb$::FieldEntry<'_, $msg_type$> {
-                  static VTABLE: $pbr$::MessageVTable =
-                    $pbr$::MessageVTable::new($pbi$::Private,
-                                              $getter_thunk$,
-                                              $getter_mut_thunk$,
-                                              $clearer_thunk$);
-                  unsafe {
-                    let has = self.has_$raw_field_name$();
-                    $pbi$::new_vtable_field_entry($pbi$::Private,
-                      self.as_mutator_message_ref(),
-                      &VTABLE,
-                      has)
-                  }
-                }
-                )rs");
+                 pub fn $raw_field_name$_mut(&mut self) -> $msg_type$Mut<'_> {
+                    $getter_mut_body$
+               })rs");
              }},
             {"getter_opt",
              [&] {
@@ -111,14 +108,44 @@ void SingularMessage::InMsgImpl(Context& ctx, const FieldDescriptor& field,
             }
             )rs");
              }},
+            {"setter_body",
+             [&] {
+               if (accessor_case == AccessorCase::VIEW) return;
+               if (ctx.is_upb()) {
+                 ctx.Emit({}, R"rs(
+                  // The message and arena are dropped after the setter. The
+                  // memory remains allocated as we fuse the arena with the
+                  // parent message's arena.
+                  let mut msg = val.into($pbi$::Private);
+                  self.as_mutator_message_ref($pbi$::Private)
+                    .arena($pbi$::Private)
+                    .fuse(msg.as_mutator_message_ref($pbi$::Private).arena($pbi$::Private));
+
+                  unsafe {
+                    $set_allocated_thunk$(self.as_mutator_message_ref($pbi$::Private).msg(),
+                      msg.as_mutator_message_ref($pbi$::Private).msg());
+                  }
+                )rs");
+               } else {
+                 ctx.Emit({}, R"rs(
+                  // Prevent the memory from being deallocated. The setter
+                  // transfers ownership of the memory to the parent message.
+                  let mut msg = std::mem::ManuallyDrop::new(val.into($pbi$::Private));
+                  unsafe {
+                    $set_allocated_thunk$(self.as_mutator_message_ref($pbi$::Private).msg(),
+                      msg.as_mutator_message_ref($pbi$::Private).msg());
+                  }
+                )rs");
+               }
+             }},
             {"setter",
              [&] {
                if (accessor_case == AccessorCase::VIEW) return;
                ctx.Emit(R"rs(
-                pub fn set_$raw_field_name$(&mut self, val: impl $pb$::SettableValue<$msg_type$>) {
-                  //~ TODO: Optimize this to not go through the
-                  //~ FieldEntry.
-                  self.$raw_field_name$_entry().set(val);
+                pub fn set_$raw_field_name$(&mut self,
+                  val: impl $pb$::IntoProxied<$msg_type$>) {
+
+                  $setter_body$
                 }
               )rs");
              }},
@@ -140,7 +167,6 @@ void SingularMessage::InMsgImpl(Context& ctx, const FieldDescriptor& field,
            R"rs(
             $getter$
             $getter_mut$
-            $private_getter_entry$
             $getter_opt$
             $setter$
             $hazzer$
@@ -156,6 +182,7 @@ void SingularMessage::InExternC(Context& ctx,
           {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
           {"clearer_thunk", ThunkName(ctx, field, "clear")},
           {"hazzer_thunk", ThunkName(ctx, field, "has")},
+          {"set_allocated_thunk", ThunkName(ctx, field, "set")},
           {"getter_mut",
            [&] {
              if (ctx.is_cpp()) {
@@ -187,12 +214,16 @@ void SingularMessage::InExternC(Context& ctx,
                   $getter_mut$
                   fn $clearer_thunk$(raw_msg: $pbr$::RawMessage);
                   fn $hazzer_thunk$(raw_msg: $pbr$::RawMessage) -> bool;
+                  fn $set_allocated_thunk$(raw_msg: $pbr$::RawMessage,
+                                    field_msg: $pbr$::RawMessage);
                )rs");
 }
 
 void SingularMessage::InThunkCc(Context& ctx,
                                 const FieldDescriptor& field) const {
   ctx.Emit({{"QualifiedMsg", cpp::QualifiedClassName(field.containing_type())},
+            {"FieldMsg", cpp::QualifiedClassName(field.message_type())},
+            {"set_allocated_thunk", ThunkName(ctx, field, "set")},
             {"getter_thunk", ThunkName(ctx, field, "get")},
             {"getter_mut_thunk", ThunkName(ctx, field, "get_mut")},
             {"clearer_thunk", ThunkName(ctx, field, "clear")},
@@ -207,6 +238,9 @@ void SingularMessage::InThunkCc(Context& ctx,
              }
              void $clearer_thunk$($QualifiedMsg$* msg) { msg->clear_$field$(); }
              bool $hazzer_thunk$($QualifiedMsg$* msg) { return msg->has_$field$(); }
+             void $set_allocated_thunk$($QualifiedMsg$* msg, $FieldMsg$* sub_msg) {
+               msg->set_allocated_$field$(sub_msg);
+             }
            )cc");
 }
 
diff --git a/src/google/protobuf/compiler/rust/accessors/singular_scalar.cc b/src/google/protobuf/compiler/rust/accessors/singular_scalar.cc
index bf8bf622d3..a3d5c62ddd 100644
--- a/src/google/protobuf/compiler/rust/accessors/singular_scalar.cc
+++ b/src/google/protobuf/compiler/rust/accessors/singular_scalar.cc
@@ -10,8 +10,8 @@
 #include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
-#include "google/protobuf/compiler/rust/accessors/helpers.h"
+#include "google/protobuf/compiler/rust/accessors/default_value.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/compiler/rust/naming.h"
 #include "google/protobuf/descriptor.h"
@@ -23,10 +23,11 @@ namespace rust {
 
 void SingularScalar::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                                AccessorCase accessor_case) const {
+  std::string field_name = FieldNameWithCollisionAvoidance(field);
   ctx.Emit(
       {
-          {"field", RsSafeName(field.name())},
-          {"raw_field_name", field.name()},  // Never r# prefixed
+          {"field", RsSafeName(field_name)},
+          {"raw_field_name", field_name},  // Never r# prefixed
           {"view_self", ViewReceiver(accessor_case)},
           {"Scalar", RsTypePath(ctx, field)},
           {"hazzer_thunk", ThunkName(ctx, field, "has")},
diff --git a/src/google/protobuf/compiler/rust/accessors/singular_string.cc b/src/google/protobuf/compiler/rust/accessors/singular_string.cc
index afb3592e75..0962229bdc 100644
--- a/src/google/protobuf/compiler/rust/accessors/singular_string.cc
+++ b/src/google/protobuf/compiler/rust/accessors/singular_string.cc
@@ -5,11 +5,12 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
+#include <string>
+
 #include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/cpp/helpers.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
-#include "google/protobuf/compiler/rust/accessors/helpers.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/compiler/rust/naming.h"
 #include "google/protobuf/descriptor.h"
@@ -21,10 +22,11 @@ namespace rust {
 
 void SingularString::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                                AccessorCase accessor_case) const {
+  std::string field_name = FieldNameWithCollisionAvoidance(field);
   ctx.Emit(
       {
-          {"field", RsSafeName(field.name())},
-          {"raw_field_name", field.name()},
+          {"field", RsSafeName(field_name)},
+          {"raw_field_name", field_name},
           {"hazzer_thunk", ThunkName(ctx, field, "has")},
           {"getter_thunk", ThunkName(ctx, field, "get")},
           {"setter_thunk", ThunkName(ctx, field, "set")},
@@ -42,18 +44,6 @@ void SingularString::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                              }
                            })
               .WithSuffix(""),  // This lets `$transform_view$,` work.
-          {"transform_field_entry",
-           [&] {
-             if (field.type() == FieldDescriptor::TYPE_STRING) {
-               ctx.Emit(R"rs(
-                $pb$::ProtoStrMut::field_entry_from_bytes(
-                  $pbi$::Private, out
-                )
-              )rs");
-             } else {
-               ctx.Emit("out");
-             }
-           }},
           {"view_lifetime", ViewLifetime(accessor_case)},
           {"view_self", ViewReceiver(accessor_case)},
           {"getter",
@@ -80,12 +70,22 @@ void SingularString::InMsgImpl(Context& ctx, const FieldDescriptor& field,
            [&] {
              if (accessor_case == AccessorCase::VIEW) return;
              ctx.Emit(R"rs(
-                pub fn set_$raw_field_name$(&mut self, val: impl $pb$::SettableValue<$proxied_type$>) {
-                  //~ TODO: Optimize this to not go through the
-                  //~ FieldEntry.
-                  self.$raw_field_name$_mut().set(val);
+              // TODO: Use IntoProxied once string/bytes types support it.
+              pub fn set_$raw_field_name$(&mut self, val: impl std::convert::AsRef<$proxied_type$>) {
+                let string_view: $pbr$::PtrAndLen =
+                  $pbr$::copy_bytes_in_arena_if_needed_by_runtime(
+                    self.as_mutator_message_ref($pbi$::Private),
+                    val.as_ref().into()
+                  ).into();
+
+                unsafe {
+                  $setter_thunk$(
+                    self.as_mutator_message_ref($pbi$::Private).msg(),
+                    string_view
+                  );
                 }
-              )rs");
+              }
+            )rs");
            }},
           {"hazzer",
            [&] {
@@ -104,74 +104,6 @@ void SingularString::InMsgImpl(Context& ctx, const FieldDescriptor& field,
                   unsafe { $clearer_thunk$(self.raw_msg()) }
                 })rs");
            }},
-          {"vtable_name", VTableName(field)},
-          {"vtable",
-           [&] {
-             if (accessor_case != AccessorCase::OWNED) {
-               return;
-             }
-             if (field.has_presence()) {
-               ctx.Emit({{"default_value", DefaultValue(ctx, field)}},
-                        R"rs(
-                // SAFETY: for `string` fields, the default value is verified as valid UTF-8
-                const $vtable_name$: &'static $pbi$::BytesOptionalMutVTable = &unsafe {
-                    $pbi$::BytesOptionalMutVTable::new(
-                      $pbi$::Private,
-                      $getter_thunk$,
-                      $setter_thunk$,
-                      $clearer_thunk$,
-                      $default_value$,
-                    )
-                  };
-              )rs");
-             } else {
-               ctx.Emit(R"rs(
-                const $vtable_name$: &'static $pbi$::BytesMutVTable =
-                  &$pbi$::BytesMutVTable::new(
-                    $pbi$::Private,
-                    $getter_thunk$,
-                    $setter_thunk$,
-                  );
-              )rs");
-             }
-           }},
-          {"field_mutator_getter",
-           [&] {
-             if (accessor_case == AccessorCase::VIEW) {
-               return;
-             }
-             if (field.has_presence()) {
-               ctx.Emit(R"rs(
-            fn $raw_field_name$_mut(&mut self) -> $pb$::FieldEntry<'_, $proxied_type$> {
-              let out = unsafe {
-                let has = $hazzer_thunk$(self.raw_msg());
-                $pbi$::new_vtable_field_entry(
-                  $pbi$::Private,
-                  self.as_mutator_message_ref(),
-                  $Msg$::$vtable_name$,
-                  has,
-                )
-              };
-              $transform_field_entry$
-            }
-          )rs");
-             } else {
-               ctx.Emit(R"rs(
-              fn $raw_field_name$_mut(&mut self) -> $pb$::Mut<'_, $proxied_type$> {
-                unsafe {
-                  <$pb$::Mut<$proxied_type$>>::from_inner(
-                    $pbi$::Private,
-                    $pbi$::RawVTableMutator::new(
-                      $pbi$::Private,
-                      self.as_mutator_message_ref(),
-                      $Msg$::$vtable_name$,
-                    )
-                  )
-                }
-              }
-            )rs");
-             }
-           }},
       },
       R"rs(
         $getter$
@@ -179,8 +111,6 @@ void SingularString::InMsgImpl(Context& ctx, const FieldDescriptor& field,
         $setter$
         $hazzer$
         $clearer$
-        $vtable$
-        $field_mutator_getter$
       )rs");
 }
 
diff --git a/src/google/protobuf/compiler/rust/accessors/unsupported_field.cc b/src/google/protobuf/compiler/rust/accessors/unsupported_field.cc
index a04e778cd0..1ca66f63ef 100644
--- a/src/google/protobuf/compiler/rust/accessors/unsupported_field.cc
+++ b/src/google/protobuf/compiler/rust/accessors/unsupported_field.cc
@@ -7,7 +7,7 @@
 
 #include "absl/strings/string_view.h"
 #include "google/protobuf/compiler/rust/accessors/accessor_case.h"
-#include "google/protobuf/compiler/rust/accessors/accessor_generator.h"
+#include "google/protobuf/compiler/rust/accessors/generator.h"
 #include "google/protobuf/compiler/rust/context.h"
 #include "google/protobuf/descriptor.h"
 
diff --git a/src/google/protobuf/compiler/rust/enum.cc b/src/google/protobuf/compiler/rust/enum.cc
index 4184ed0975..0ed50e98f0 100644
--- a/src/google/protobuf/compiler/rust/enum.cc
+++ b/src/google/protobuf/compiler/rust/enum.cc
@@ -325,23 +325,21 @@ void GenerateEnumDefinition(Context& ctx, const EnumDescriptor& desc) {
           // The default value of an enum is the first listed value.
           // The compiler checks that this is equal to 0 for open enums.
           {"default_int_value", absl::StrCat(desc.value(0)->number())},
+          {"known_values_pattern",
+           // TODO: Check validity in UPB/C++.
+           absl::StrJoin(values, "|",
+                         [](std::string* o, const RustEnumValue& val) {
+                           absl::StrAppend(o, val.number);
+                         })},
           {"impl_from_i32",
            [&] {
              if (desc.is_closed()) {
-               ctx.Emit({{"name", name},
-                         {"known_values_pattern",
-                          // TODO: Check validity in UPB/C++.
-                          absl::StrJoin(
-                              values, "|",
-                              [](std::string* o, const RustEnumValue& val) {
-                                absl::StrAppend(o, val.number);
-                              })}},
-                        R"rs(
+               ctx.Emit(R"rs(
               impl $std$::convert::TryFrom<i32> for $name$ {
                 type Error = $pb$::UnknownEnumValue<Self>;
 
                 fn try_from(val: i32) -> Result<$name$, Self::Error> {
-                  if matches!(val, $known_values_pattern$) {
+                  if <Self as $pbi$::Enum>::is_known(val) {
                     Ok(Self(val))
                   } else {
                     Err($pb$::UnknownEnumValue::new($pbi$::Private, val))
@@ -350,7 +348,7 @@ void GenerateEnumDefinition(Context& ctx, const EnumDescriptor& desc) {
               }
             )rs");
              } else {
-               ctx.Emit({{"name", name}}, R"rs(
+               ctx.Emit(R"rs(
               impl $std$::convert::From<i32> for $name$ {
                 fn from(val: i32) -> $name$ {
                   Self(val)
@@ -393,7 +391,6 @@ void GenerateEnumDefinition(Context& ctx, const EnumDescriptor& desc) {
 
       impl $pb$::Proxied for $name$ {
         type View<'a> = $name$;
-        type Mut<'a> = $pb$::PrimitiveMut<'a, $name$>;
       }
 
       impl $pb$::ViewProxy<'_> for $name$ {
@@ -408,33 +405,6 @@ void GenerateEnumDefinition(Context& ctx, const EnumDescriptor& desc) {
         }
       }
 
-      impl $pb$::SettableValue<$name$> for $name$ {
-        fn set_on<'msg>(
-            self,
-            private: $pbi$::Private,
-            mut mutator: $pb$::Mut<'msg, $name$>
-        ) where $name$: 'msg {
-          mutator.set_primitive(private, self)
-        }
-      }
-
-      impl $pb$::ProxiedWithPresence for $name$ {
-        type PresentMutData<'a> = $pbi$::RawVTableOptionalMutatorData<'a, $name$>;
-        type AbsentMutData<'a> = $pbi$::RawVTableOptionalMutatorData<'a, $name$>;
-
-        fn clear_present_field(
-          present_mutator: Self::PresentMutData<'_>,
-        ) -> Self::AbsentMutData<'_> {
-          present_mutator.clear($pbi$::Private)
-        }
-
-        fn set_absent_to_default(
-          absent_mutator: Self::AbsentMutData<'_>,
-        ) -> Self::PresentMutData<'_> {
-          absent_mutator.set_absent_to_default($pbi$::Private)
-        }
-      }
-
       unsafe impl $pb$::ProxiedInRepeated for $name$ {
         fn repeated_len(r: $pb$::View<$pb$::Repeated<Self>>) -> usize {
           $pbr$::cast_enum_repeated_view($pbi$::Private, r).len()
@@ -480,13 +450,24 @@ void GenerateEnumDefinition(Context& ctx, const EnumDescriptor& desc) {
           $pbr$::cast_enum_repeated_mut($pbi$::Private, dest)
             .copy_from($pbr$::cast_enum_repeated_view($pbi$::Private, src))
         }
-      }
 
-      impl $pbi$::PrimitiveWithRawVTable for $name$ {}
+        fn repeated_reserve(
+            mut r: $pb$::Mut<$pb$::Repeated<Self>>,
+            additional: usize,
+        ) {
+            // SAFETY:
+            // - `f.as_raw()` is valid.
+            $pbr$::reserve_enum_repeated_mut($pbi$::Private, r, additional);
+        }
+      }
 
       // SAFETY: this is an enum type
       unsafe impl $pbi$::Enum for $name$ {
         const NAME: &'static str = "$name$";
+
+        fn is_known(value: i32) -> bool {
+          matches!(value, $known_values_pattern$)
+        }
       }
 
       $impl_proxied_in_map$
diff --git a/src/google/protobuf/compiler/rust/generator.cc b/src/google/protobuf/compiler/rust/generator.cc
index 71a8c1b107..49f1e65897 100644
--- a/src/google/protobuf/compiler/rust/generator.cc
+++ b/src/google/protobuf/compiler/rust/generator.cc
@@ -202,11 +202,23 @@ bool RustGenerator::Generate(const FileDescriptor* file,
     thunks_cc.reset(generator_context->Open(GetThunkCcFile(ctx, *file)));
     thunks_printer = std::make_unique<io::Printer>(thunks_cc.get());
 
-    thunks_printer->Emit({{"proto_h", GetHeaderFile(ctx, *file)}},
-                         R"cc(
+    thunks_printer->Emit(
+        {{"proto_h", GetHeaderFile(ctx, *file)},
+         {"proto_deps_h",
+          [&] {
+            for (int i = 0; i < file->dependency_count(); i++) {
+              thunks_printer->Emit(
+                  {{"proto_dep_h", GetHeaderFile(ctx, *file->dependency(i))}},
+                  R"cc(
+#include "$proto_dep_h$"
+                  )cc");
+            }
+          }}},
+        R"cc(
 #include "$proto_h$"
+          $proto_deps_h$
 #include "google/protobuf/rust/cpp_kernel/cpp_api.h"
-                         )cc");
+        )cc");
   }
 
   for (int i = 0; i < file->message_type_count(); ++i) {
diff --git a/src/google/protobuf/compiler/rust/message.cc b/src/google/protobuf/compiler/rust/message.cc
index 6ee718fc18..69d6f3ff06 100644
--- a/src/google/protobuf/compiler/rust/message.cc
+++ b/src/google/protobuf/compiler/rust/message.cc
@@ -68,35 +68,17 @@ void MessageSerialize(Context& ctx, const Descriptor& msg) {
     case Kernel::kUpb:
       ctx.Emit({{"minitable", UpbMinitableName(msg)}},
                R"rs(
-        let arena = $pbr$::Arena::new();
         // SAFETY: $minitable$ is a static of a const object.
         let mini_table = unsafe { $std$::ptr::addr_of!($minitable$) };
-        let options = 0;
-        let mut buf: *mut u8 = std::ptr::null_mut();
-        let mut len = 0;
-
-        // SAFETY: `mini_table` is the corresponding one that was used to
-        // construct `self.raw_msg()`.
-        let status = unsafe {
-          $pbr$::upb_Encode(self.raw_msg(), mini_table, options, arena.raw(),
-              &mut buf, &mut len)
+        // SAFETY: $minitable$ is the one associated with raw_msg().
+        let encoded = unsafe {
+          $pbr$::wire::encode(self.raw_msg(), mini_table)
         };
 
         //~ TODO: Currently serialize() on the Rust API is an
         //~ infallible fn, so if upb signals an error here we can only panic.
-        assert!(status == $pbr$::EncodeStatus::Ok);
-        let data = if len == 0 {
-          std::ptr::NonNull::dangling()
-        } else {
-          std::ptr::NonNull::new(buf).unwrap()
-        };
-
-        // SAFETY:
-        // - `arena` allocated `data`.
-        // - `data` is valid for reads up to `len` and will not be mutated.
-        unsafe {
-          $pbr$::SerializedData::from_raw_parts(arena, data, len)
-        }
+        let serialized = encoded.expect("serialize is not allowed to fail");
+        serialized
       )rs");
       return;
   }
@@ -131,27 +113,25 @@ void MessageClearAndParse(Context& ctx, const Descriptor& msg) {
         let mut msg = Self::new();
         // SAFETY: $minitable$ is a static of a const object.
         let mini_table = unsafe { $std$::ptr::addr_of!($minitable$) };
-        let ext_reg = std::ptr::null();
-        let options = 0;
 
         // SAFETY:
         // - `data.as_ptr()` is valid to read for `data.len()`
         // - `mini_table` is the one used to construct `msg.raw_msg()`
         // - `msg.arena().raw()` is held for the same lifetime as `msg`.
         let status = unsafe {
-          $pbr$::upb_Decode(
-              data.as_ptr(), data.len(), msg.raw_msg(),
-              mini_table, ext_reg, options, msg.arena().raw())
+          $pbr$::wire::decode(
+              data, msg.raw_msg(),
+              mini_table, msg.arena())
         };
         match status {
-          $pbr$::DecodeStatus::Ok => {
+          Ok(_) => {
             //~ This swap causes the old self.inner.arena to be moved into `msg`
             //~ which we immediately drop, which will release any previous
             //~ message that was held here.
             std::mem::swap(self, &mut msg);
             Ok(())
           }
-          _ => Err($pb$::ParseError)
+          Err(_) => Err($pb$::ParseError)
         }
       )rs");
       return;
@@ -200,6 +180,8 @@ void MessageExterns(Context& ctx, const Descriptor& msg) {
               {"repeated_clear_thunk", ThunkName(ctx, msg, "repeated_clear")},
               {"repeated_copy_from_thunk",
                ThunkName(ctx, msg, "repeated_copy_from")},
+              {"repeated_reserve_thunk",
+               ThunkName(ctx, msg, "repeated_reserve")},
           },
           R"rs(
           fn $new_thunk$() -> $pbr$::RawMessage;
@@ -213,6 +195,7 @@ void MessageExterns(Context& ctx, const Descriptor& msg) {
           fn $repeated_get_mut_thunk$(raw: $pbr$::RawRepeatedField, index: usize) -> $pbr$::RawMessage;
           fn $repeated_clear_thunk$(raw: $pbr$::RawRepeatedField);
           fn $repeated_copy_from_thunk$(dst: $pbr$::RawRepeatedField, src: $pbr$::RawRepeatedField);
+          fn $repeated_reserve_thunk$(raw: $pbr$::RawRepeatedField, additional: usize);
         )rs");
       return;
 
@@ -246,33 +229,56 @@ void MessageDrop(Context& ctx, const Descriptor& msg) {
   )rs");
 }
 
-void MessageSettableValueForView(Context& ctx, const Descriptor& msg) {
+void IntoProxiedForMessage(Context& ctx, const Descriptor& msg) {
   switch (ctx.opts().kernel) {
     case Kernel::kCpp:
       ctx.Emit({{"copy_from_thunk", ThunkName(ctx, msg, "copy_from")}}, R"rs(
-        impl<'msg> $pb$::SettableValue<$Msg$> for $Msg$View<'msg> {
-          fn set_on<'dst>(
-            self, _private: $pbi$::Private, mutator: $pb$::Mut<'dst, $Msg$>)
-            where $Msg$: 'dst {
-            unsafe { $copy_from_thunk$(mutator.inner.msg(), self.msg) };
+        impl<'msg> $pb$::IntoProxied<$Msg$> for $Msg$View<'msg> {
+          fn into(self, _private: $pbi$::Private) -> $Msg$ {
+            let dst = $Msg$::new();
+            unsafe { $copy_from_thunk$(dst.inner.msg, self.msg) };
+            dst
+          }
+        }
+
+        impl<'msg> $pb$::IntoProxied<$Msg$> for $Msg$Mut<'msg> {
+          fn into(self, _private: $pbi$::Private) -> $Msg$ {
+            $pb$::IntoProxied::into($pb$::ViewProxy::into_view(self), _private)
+          }
+        }
+
+        impl $pb$::IntoProxied<$Msg$> for $Msg$ {
+          fn into(self, _private: $pbi$::Private) -> $Msg$ {
+            self
           }
         }
       )rs");
       return;
 
     case Kernel::kUpb:
-      // TODO: Add owned SettableValue impl for upb messages.
       ctx.Emit({{"minitable", UpbMinitableName(msg)}}, R"rs(
-        impl<'msg> $pb$::SettableValue<$Msg$> for $Msg$View<'msg> {
-          fn set_on<'dst>(
-            self, _private: $pbi$::Private, mutator: $pb$::Mut<'dst, $Msg$>)
-            where $Msg$: 'dst {
+        impl<'msg> $pb$::IntoProxied<$Msg$> for $Msg$View<'msg> {
+          fn into(self, _private: $pbi$::Private) -> $Msg$ {
+            let dst = $Msg$::new();
             unsafe { $pbr$::upb_Message_DeepCopy(
-              mutator.inner.msg(),
+              dst.inner.msg,
               self.msg,
               $std$::ptr::addr_of!($minitable$),
-              mutator.inner.arena($pbi$::Private).raw(),
+              dst.inner.arena.raw(),
             ) };
+            dst
+          }
+        }
+
+        impl<'msg> $pb$::IntoProxied<$Msg$> for $Msg$Mut<'msg> {
+          fn into(self, _private: $pbi$::Private) -> $Msg$ {
+            $pb$::IntoProxied::into($pb$::ViewProxy::into_view(self), _private)
+          }
+        }
+
+        impl $pb$::IntoProxied<$Msg$> for $Msg$ {
+          fn into(self, _private: $pbi$::Private) -> $Msg$ {
+            self
           }
         }
       )rs");
@@ -282,6 +288,16 @@ void MessageSettableValueForView(Context& ctx, const Descriptor& msg) {
   ABSL_LOG(FATAL) << "unreachable";
 }
 
+void MessageGetMinitable(Context& ctx, const Descriptor& msg) {
+  if (ctx.opts().kernel == Kernel::kUpb) {
+    ctx.Emit({{"minitable", UpbMinitableName(msg)}}, R"rs(
+      pub fn raw_minitable(_private: $pbi$::Private) -> *const $pbr$::upb_MiniTable {
+        unsafe { $std$::ptr::addr_of!($minitable$) }
+      }
+    )rs");
+  }
+}
+
 void MessageProxiedInRepeated(Context& ctx, const Descriptor& msg) {
   switch (ctx.opts().kernel) {
     case Kernel::kCpp:
@@ -297,6 +313,8 @@ void MessageProxiedInRepeated(Context& ctx, const Descriptor& msg) {
               {"repeated_clear_thunk", ThunkName(ctx, msg, "repeated_clear")},
               {"repeated_copy_from_thunk",
                ThunkName(ctx, msg, "repeated_copy_from")},
+              {"repeated_reserve_thunk",
+               ThunkName(ctx, msg, "repeated_reserve")},
           },
           R"rs(
         unsafe impl $pb$::ProxiedInRepeated for $Msg$ {
@@ -359,8 +377,16 @@ void MessageProxiedInRepeated(Context& ctx, const Descriptor& msg) {
               $repeated_copy_from_thunk$(dest.as_raw($pbi$::Private), src.as_raw($pbi$::Private));
             }
           }
-        }
 
+          fn repeated_reserve(
+            mut f: $pb$::Mut<$pb$::Repeated<Self>>,
+            additional: usize,
+          ) {
+            // SAFETY:
+            // - `f.as_raw()` is a valid `RepeatedPtrField*`.
+            unsafe { $repeated_reserve_thunk$(f.as_raw($pbi$::Private), additional) }
+          }
+        }
       )rs");
       return;
     case Kernel::kUpb:
@@ -453,6 +479,18 @@ void MessageProxiedInRepeated(Context& ctx, const Descriptor& msg) {
                 $pbr$::repeated_message_copy_from(src, dest, $std$::ptr::addr_of!($minitable$));
               }
           }
+
+          fn repeated_reserve(
+            mut f: $pb$::Mut<$pb$::Repeated<Self>>,
+            additional: usize,
+          ) {
+            // SAFETY:
+            // - `f.as_raw()` is a valid `upb_Array*`.
+            unsafe {
+              let size = $pbr$::upb_Array_Size(f.as_raw($pbi$::Private));
+              $pbr$::upb_Array_Reserve(f.as_raw($pbi$::Private), size + additional, f.raw_arena($pbi$::Private));
+            }
+          }
         }
       )rs");
       return;
@@ -817,8 +855,8 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
                                    AccessorCase::MUT);
           }
         }},
-       {"settable_impl_for_view",
-        [&] { MessageSettableValueForView(ctx, msg); }},
+       {"into_proxied_impl", [&] { IntoProxiedForMessage(ctx, msg); }},
+       {"get_upb_minitable", [&] { MessageGetMinitable(ctx, msg); }},
        {"repeated_impl", [&] { MessageProxiedInRepeated(ctx, msg); }},
        {"map_value_impl", [&] { MessageProxiedInMapValue(ctx, msg); }},
        {"unwrap_upb",
@@ -865,6 +903,9 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
 
         impl $pb$::Proxied for $Msg$ {
           type View<'msg> = $Msg$View<'msg>;
+        }
+
+        impl $pb$::MutProxied for $Msg$ {
           type Mut<'msg> = $Msg$Mut<'msg>;
         }
 
@@ -896,6 +937,10 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             $Msg::serialize$
           }
 
+          pub fn to_owned(&self) -> $Msg$ {
+            $pb$::IntoProxied::into(*self, $pbi$::Private)
+          }
+
           $accessor_fns_for_views$
         }
 
@@ -919,75 +964,7 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
           }
         }
 
-        impl $pbi$::ProxiedWithRawVTable for $Msg$ {
-          type VTable = $pbr$::MessageVTable;
-
-          fn make_view(_private: $pbi$::Private,
-                      mut_inner: $pbi$::RawVTableMutator<'_, Self>)
-                      -> $pb$::View<'_, Self> {
-            let msg = unsafe {
-              (mut_inner.vtable().getter)(mut_inner.msg_ref().msg())
-            };
-            $Msg$View::new($pbi$::Private, msg$unwrap_upb$)
-          }
-
-          fn make_mut(_private: $pbi$::Private,
-                      inner: $pbi$::RawVTableMutator<'_, Self>)
-                      -> $pb$::Mut<'_, Self> {
-            let raw_submsg = unsafe {
-              (inner.vtable().mut_getter)(inner.msg_ref().msg()$upb_arena$)
-            };
-            $Msg$Mut::from_parent($pbi$::Private, inner.msg_ref(), raw_submsg)
-          }
-        }
-
-        impl $pbi$::ProxiedWithRawOptionalVTable for $Msg$ {
-          type OptionalVTable = $pbr$::MessageVTable;
-
-          fn upcast_vtable(_private: $pbi$::Private,
-                           optional_vtable: &'static Self::OptionalVTable)
-                          -> &'static Self::VTable {
-            &optional_vtable
-          }
-        }
-
-        impl $pb$::ProxiedWithPresence for $Msg$ {
-          type PresentMutData<'a> = $pbr$::MessagePresentMutData<'a, $Msg$>;
-          type AbsentMutData<'a> = $pbr$::MessageAbsentMutData<'a, $Msg$>;
-
-          fn clear_present_field(present_mutator: Self::PresentMutData<'_>)
-             -> Self::AbsentMutData<'_> {
-             // SAFETY: The raw ptr msg_ref is valid
-            unsafe {
-              (present_mutator.optional_vtable().clearer)(present_mutator.msg_ref().msg());
-
-             $pbi$::RawVTableOptionalMutatorData::new($pbi$::Private,
-               present_mutator.msg_ref(),
-               present_mutator.optional_vtable())
-            }
-          }
-
-          fn set_absent_to_default(absent_mutator: Self::AbsentMutData<'_>)
-             -> Self::PresentMutData<'_> {
-           unsafe {
-             $pbi$::RawVTableOptionalMutatorData::new($pbi$::Private,
-               absent_mutator.msg_ref(),
-               absent_mutator.optional_vtable())
-           }
-          }
-        }
-
-        $settable_impl_for_view$
-
-        impl $pb$::SettableValue<$Msg$> for $Msg$ {
-          fn set_on<'dst>(
-            self, _private: $pbi$::Private, mutator: $pb$::Mut<'dst, $Msg$>)
-            where $Msg$: 'dst {
-            //~ TODO: b/320701507 - This current will copy the message and then
-            //~ drop it, this copy would be avoided on upb kernel.
-            self.as_view().set_on($pbi$::Private, mutator);
-          }
-        }
+        $into_proxied_impl$
 
         $repeated_impl$
         $map_value_impl$
@@ -1030,7 +1007,8 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             self.inner.msg()
           }
 
-          fn as_mutator_message_ref(&mut self) -> $pbr$::MutatorMessageRef<'msg> {
+          pub fn as_mutator_message_ref(&mut self, _private: $pbi$::Private)
+            -> $pbr$::MutatorMessageRef<'msg> {
             self.inner
           }
 
@@ -1038,6 +1016,12 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             $pb$::ViewProxy::as_view(self).serialize()
           }
 
+          pub fn to_owned(&self) -> $Msg$ {
+            $pb$::ViewProxy::as_view(self).to_owned()
+          }
+
+          $get_upb_minitable$
+
           $raw_arena_getter_for_msgmut$
 
           $accessor_fns_for_muts$
@@ -1076,7 +1060,7 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             self.inner.msg
           }
 
-          fn as_mutator_message_ref(&mut self) -> $pbr$::MutatorMessageRef {
+          pub fn as_mutator_message_ref(&mut self, _private: $pbi$::Private) -> $pbr$::MutatorMessageRef {
             $pbr$::MutatorMessageRef::new($pbi$::Private, &mut self.inner)
           }
 
@@ -1105,6 +1089,8 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
             $Msg$Mut::new($pbi$::Private, &mut self.inner)
           }
 
+          $get_upb_minitable$
+
           $accessor_fns$
         }  // impl $Msg$
 
@@ -1116,6 +1102,12 @@ void GenerateRs(Context& ctx, const Descriptor& msg) {
           }
         }
 
+        impl $std$::clone::Clone for $Msg$ {
+          fn clone(&self) -> Self {
+            self.as_view().to_owned()
+          }
+        }
+
         extern "C" {
           $Msg_externs$
 
@@ -1192,6 +1184,7 @@ void GenerateThunksCc(Context& ctx, const Descriptor& msg) {
        {"repeated_add_thunk", ThunkName(ctx, msg, "repeated_add")},
        {"repeated_clear_thunk", ThunkName(ctx, msg, "repeated_clear")},
        {"repeated_copy_from_thunk", ThunkName(ctx, msg, "repeated_copy_from")},
+       {"repeated_reserve_thunk", ThunkName(ctx, msg, "repeated_reserve")},
        {"nested_msg_thunks",
         [&] {
           for (int i = 0; i < msg.nested_type_count(); ++i) {
@@ -1257,6 +1250,11 @@ void GenerateThunksCc(Context& ctx, const Descriptor& msg) {
           const google::protobuf::RepeatedPtrField<$QualifiedMsg$>& src) {
           dst = src;
         }
+        void $repeated_reserve_thunk$(
+          google::protobuf::RepeatedPtrField<$QualifiedMsg$>* field,
+          size_t additional) {
+          field->Reserve(field->size() + additional);
+        }
 
         $accessor_thunks$
 
diff --git a/src/google/protobuf/compiler/rust/naming.cc b/src/google/protobuf/compiler/rust/naming.cc
index 6879e4ae45..78d96b8393 100644
--- a/src/google/protobuf/compiler/rust/naming.cc
+++ b/src/google/protobuf/compiler/rust/naming.cc
@@ -270,6 +270,40 @@ std::string FieldInfoComment(Context& ctx, const FieldDescriptor& field) {
   return comment;
 }
 
+static constexpr absl::string_view kAccessorPrefixes[] = {"clear_", "has_",
+                                                          "set_"};
+
+static constexpr absl::string_view kAccessorSuffixes[] = {"_mut", "_opt"};
+
+std::string FieldNameWithCollisionAvoidance(const FieldDescriptor& field) {
+  absl::string_view name = field.name();
+  const Descriptor& msg = *field.containing_type();
+
+  for (absl::string_view prefix : kAccessorPrefixes) {
+    if (absl::StartsWith(name, prefix)) {
+      absl::string_view without_prefix = name;
+      without_prefix.remove_prefix(prefix.size());
+
+      if (msg.FindFieldByName(without_prefix) != nullptr) {
+        return absl::StrCat(name, "_", field.number());
+      }
+    }
+  }
+
+  for (absl::string_view suffix : kAccessorSuffixes) {
+    if (absl::EndsWith(name, suffix)) {
+      absl::string_view without_suffix = name;
+      without_suffix.remove_suffix(suffix.size());
+
+      if (msg.FindFieldByName(without_suffix) != nullptr) {
+        return absl::StrCat(name, "_", field.number());
+      }
+    }
+  }
+
+  return std::string(name);
+}
+
 std::string RsSafeName(absl::string_view name) {
   if (!IsLegalRawIdentifierName(name)) {
     return absl::StrCat(name,
diff --git a/src/google/protobuf/compiler/rust/naming.h b/src/google/protobuf/compiler/rust/naming.h
index f3d7af797e..70eebe1b64 100644
--- a/src/google/protobuf/compiler/rust/naming.h
+++ b/src/google/protobuf/compiler/rust/naming.h
@@ -55,6 +55,25 @@ std::string OneofCaseRsName(const FieldDescriptor& oneof_field);
 
 std::string FieldInfoComment(Context& ctx, const FieldDescriptor& field);
 
+// Return how to name a field with 'collision avoidance'. This adds a suffix
+// of the field number to the field name if it appears that it will collide with
+// another field's non-getter accessor.
+//
+// For example, for the message:
+// message M { bool set_x = 1; int32 x = 2; string x_mut = 8; }
+// All accessors for the field `set_x` will be constructed as though the field
+// was instead named `set_x_1`, and all accessors for `x_mut` will be as though
+// the field was instead named `x_mut_8`.
+//
+// This is a best-effort heuristic to avoid realistic accidental
+// collisions. It is still possible to create a message definition that will
+// have a collision, and it may rename a field even if there's no collision (as
+// in the case of x_mut in the example).
+//
+// Note the returned name may still be a rust keyword: RsSafeName() should
+// additionally be used if there is no prefix/suffix being appended to the name.
+std::string FieldNameWithCollisionAvoidance(const FieldDescriptor& field);
+
 // Returns how to 'spell' the provided name in Rust, which is the provided name
 // verbatim unless it is a Rust keyword that isn't a legal symbol name.
 std::string RsSafeName(absl::string_view name);
diff --git a/src/google/protobuf/compiler/rust/oneof.cc b/src/google/protobuf/compiler/rust/oneof.cc
index 8453af898b..fc8cef2f18 100644
--- a/src/google/protobuf/compiler/rust/oneof.cc
+++ b/src/google/protobuf/compiler/rust/oneof.cc
@@ -193,10 +193,11 @@ void GenerateOneofAccessors(Context& ctx, const OneofDescriptor& oneof,
                if (rs_type.empty()) {
                  continue;
                }
+               std::string field_name = FieldNameWithCollisionAvoidance(field);
                ctx.Emit(
                    {
                        {"case", OneofCaseRsName(field)},
-                       {"rs_getter", RsSafeName(field.name())},
+                       {"rs_getter", RsSafeName(field_name)},
                        {"type", rs_type},
                    },
                    R"rs(
diff --git a/src/google/protobuf/cpp_features.pb.cc b/src/google/protobuf/cpp_features.pb.cc
index 0e82110847..71f69b9793 100644
--- a/src/google/protobuf/cpp_features.pb.cc
+++ b/src/google/protobuf/cpp_features.pb.cc
@@ -287,27 +287,26 @@ PROTOBUF_NOINLINE void CppFeatures::Clear() {
 }
 
 ::size_t CppFeatures::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:pb.CppFeatures)
+  // @@protoc_insertion_point(message_byte_size_start:pb.CppFeatures)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // optional bool legacy_closed_enum = 1 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000001u) {
       total_size += 2;
     }
-
     // optional .pb.CppFeatures.StringType string_type = 2 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_string_type());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
diff --git a/src/google/protobuf/descriptor.cc b/src/google/protobuf/descriptor.cc
index db45ca90ca..7264daff6a 100644
--- a/src/google/protobuf/descriptor.cc
+++ b/src/google/protobuf/descriptor.cc
@@ -2808,7 +2808,7 @@ bool DescriptorPool::TryFindExtensionInFallbackDatabase(
 // ===================================================================
 
 bool FieldDescriptor::is_map_message_type() const {
-  return type_descriptor_.message_type->options().map_entry();
+  return message_type()->options().map_entry();
 }
 
 std::string FieldDescriptor::DefaultValueAsString(
@@ -4362,7 +4362,8 @@ class DescriptorBuilder {
       DescriptorPool::ErrorCollector::ErrorLocation error_location,
       bool force_merge = false);
 
-  void PostProcessFieldFeatures(FieldDescriptor& field);
+  void PostProcessFieldFeatures(FieldDescriptor& field,
+                                const FieldDescriptorProto& proto);
 
   // Allocates an array of two strings, the first one is a copy of
   // `proto_name`, and the second one is the full name. Full proto name is
@@ -5542,7 +5543,8 @@ void DescriptorBuilder::ResolveFeatures(const FileDescriptorProto& proto,
                       /*force_merge=*/true);
 }
 
-void DescriptorBuilder::PostProcessFieldFeatures(FieldDescriptor& field) {
+void DescriptorBuilder::PostProcessFieldFeatures(
+    FieldDescriptor& field, const FieldDescriptorProto& proto) {
   // TODO This can be replace by a runtime check in `is_required`
   // once the `label` getter is hidden.
   if (field.features().field_presence() == FeatureSet::LEGACY_REQUIRED &&
@@ -5552,8 +5554,15 @@ void DescriptorBuilder::PostProcessFieldFeatures(FieldDescriptor& field) {
   // TODO This can be replace by a runtime check of `is_delimited`
   // once the `TYPE_GROUP` value is removed.
   if (field.type_ == FieldDescriptor::TYPE_MESSAGE &&
+      !field.containing_type()->options().map_entry() &&
       field.features().message_encoding() == FeatureSet::DELIMITED) {
-    field.type_ = FieldDescriptor::TYPE_GROUP;
+    Symbol type =
+        LookupSymbol(proto.type_name(), field.full_name(),
+                     DescriptorPool::PLACEHOLDER_MESSAGE, LOOKUP_TYPES, false);
+    if (type.descriptor() == nullptr ||
+        !type.descriptor()->options().map_entry()) {
+      field.type_ = FieldDescriptor::TYPE_GROUP;
+    }
   }
 }
 
@@ -6099,9 +6108,11 @@ FileDescriptor* DescriptorBuilder::BuildFileImpl(
         });
 
     // Post-process cleanup for field features.
-    internal::VisitDescriptors(*result, [&](const FieldDescriptor& field) {
-      PostProcessFieldFeatures(const_cast<FieldDescriptor&>(field));
-    });
+    internal::VisitDescriptors(
+        *result, proto,
+        [&](const FieldDescriptor& field, const FieldDescriptorProto& proto) {
+          PostProcessFieldFeatures(const_cast<FieldDescriptor&>(field), proto);
+        });
 
     // Interpret any remaining uninterpreted options gathered into
     // options_to_interpret_ during descriptor building.  Cross-linking has made
@@ -6503,12 +6514,8 @@ void DescriptorBuilder::BuildFieldOrExtension(const FieldDescriptorProto& proto,
 
   result->has_json_name_ = proto.has_json_name();
 
-  // Some compilers do not allow static_cast directly between two enum types,
-  // so we must cast to int first.
-  result->type_ = static_cast<FieldDescriptor::Type>(
-      absl::implicit_cast<int>(proto.type()));
-  result->label_ = static_cast<FieldDescriptor::Label>(
-      absl::implicit_cast<int>(proto.label()));
+  result->type_ = proto.type();
+  result->label_ = proto.label();
   result->is_repeated_ = result->label_ == FieldDescriptor::LABEL_REPEATED;
 
   if (result->label() == FieldDescriptor::LABEL_REQUIRED) {
@@ -7388,6 +7395,10 @@ void DescriptorBuilder::CrossLinkField(FieldDescriptor* field,
 
     if (type.IsNull()) {
       if (is_lazy) {
+        ABSL_CHECK(field->type_ == FieldDescriptor::TYPE_MESSAGE ||
+                   field->type_ == FieldDescriptor::TYPE_GROUP ||
+                   field->type_ == FieldDescriptor::TYPE_ENUM)
+            << proto;
         // Save the symbol names for later for lookup, and allocate the once
         // object needed for the accessors.
         const std::string& name = proto.type_name();
@@ -8073,16 +8084,16 @@ void DescriptorBuilder::ValidateFieldFeatures(
   }
 
   // Validate fully resolved features.
-  if (field->has_default_value() &&
-      field->features().field_presence() == FeatureSet::IMPLICIT) {
-    AddError(field->full_name(), proto, DescriptorPool::ErrorCollector::NAME,
-             "Implicit presence fields can't specify defaults.");
-  }
-  if (field->enum_type() != nullptr &&
-      field->enum_type()->features().enum_type() != FeatureSet::OPEN &&
-      field->features().field_presence() == FeatureSet::IMPLICIT) {
-    AddError(field->full_name(), proto, DescriptorPool::ErrorCollector::NAME,
-             "Implicit presence enum fields must always be open.");
+  if (!field->is_repeated() && !field->has_presence()) {
+    if (field->has_default_value()) {
+      AddError(field->full_name(), proto, DescriptorPool::ErrorCollector::NAME,
+               "Implicit presence fields can't specify defaults.");
+    }
+    if (field->enum_type() != nullptr &&
+        field->enum_type()->features().enum_type() != FeatureSet::OPEN) {
+      AddError(field->full_name(), proto, DescriptorPool::ErrorCollector::NAME,
+               "Implicit presence enum fields must always be open.");
+    }
   }
   if (field->is_extension() &&
       field->features().field_presence() == FeatureSet::LEGACY_REQUIRED) {
@@ -8579,7 +8590,7 @@ bool DescriptorBuilder::OptionInterpreter::InterpretOptionsImpl(
           *original_options, original_uninterpreted_options_field);
   for (int i = 0; i < num_uninterpreted_options; ++i) {
     src_path.push_back(i);
-    uninterpreted_option_ = DownCast<const UninterpretedOption*>(
+    uninterpreted_option_ = DownCastToGenerated<UninterpretedOption>(
         &original_options->GetReflection()->GetRepeatedMessage(
             *original_options, original_uninterpreted_options_field, i));
     if (!InterpretSingleOption(options, src_path,
@@ -9149,6 +9160,10 @@ bool DescriptorBuilder::OptionInterpreter::SetOptionValue(
         value = uninterpreted_option_->positive_int_value();
       } else if (uninterpreted_option_->has_negative_int_value()) {
         value = uninterpreted_option_->negative_int_value();
+      } else if (uninterpreted_option_->identifier_value() == "inf") {
+        value = std::numeric_limits<float>::infinity();
+      } else if (uninterpreted_option_->identifier_value() == "nan") {
+        value = std::numeric_limits<float>::quiet_NaN();
       } else {
         return AddValueError([&] {
           return absl::StrCat("Value must be number for float option \"",
@@ -9168,6 +9183,10 @@ bool DescriptorBuilder::OptionInterpreter::SetOptionValue(
         value = uninterpreted_option_->positive_int_value();
       } else if (uninterpreted_option_->has_negative_int_value()) {
         value = uninterpreted_option_->negative_int_value();
+      } else if (uninterpreted_option_->identifier_value() == "inf") {
+        value = std::numeric_limits<double>::infinity();
+      } else if (uninterpreted_option_->identifier_value() == "nan") {
+        value = std::numeric_limits<double>::quiet_NaN();
       } else {
         return AddValueError([&] {
           return absl::StrCat("Value must be number for double option \"",
@@ -9576,19 +9595,23 @@ void FieldDescriptor::TypeOnceInit(const FieldDescriptor* to_init) {
 // all share the same absl::call_once init path to do lazy
 // import building and cross linking of a field of a message.
 const Descriptor* FieldDescriptor::message_type() const {
-  if (type_once_) {
-    absl::call_once(*type_once_, FieldDescriptor::TypeOnceInit, this);
+  if (type_ == TYPE_MESSAGE || type_ == TYPE_GROUP) {
+    if (type_once_) {
+      absl::call_once(*type_once_, FieldDescriptor::TypeOnceInit, this);
+    }
+    return type_descriptor_.message_type;
   }
-  return type_ == TYPE_MESSAGE || type_ == TYPE_GROUP
-             ? type_descriptor_.message_type
-             : nullptr;
+  return nullptr;
 }
 
 const EnumDescriptor* FieldDescriptor::enum_type() const {
-  if (type_once_) {
-    absl::call_once(*type_once_, FieldDescriptor::TypeOnceInit, this);
+  if (type_ == TYPE_ENUM) {
+    if (type_once_) {
+      absl::call_once(*type_once_, FieldDescriptor::TypeOnceInit, this);
+    }
+    return type_descriptor_.enum_type;
   }
-  return type_ == TYPE_ENUM ? type_descriptor_.enum_type : nullptr;
+  return nullptr;
 }
 
 const EnumValueDescriptor* FieldDescriptor::default_value_enum() const {
diff --git a/src/google/protobuf/descriptor.h b/src/google/protobuf/descriptor.h
index 443454543d..e4898950b2 100644
--- a/src/google/protobuf/descriptor.h
+++ b/src/google/protobuf/descriptor.h
@@ -1090,7 +1090,7 @@ class PROTOBUF_EXPORT FieldDescriptor : private internal::SymbolBase,
   uint8_t label_ : 2;
 
   // Actually a `Type`, but stored as uint8_t to save space.
-  mutable uint8_t type_;
+  uint8_t type_;
 
   // Logically:
   //   all_names_ = [name, full_name, lower, camel, json]
@@ -2676,9 +2676,6 @@ inline FieldDescriptor::Label FieldDescriptor::label() const {
 }
 
 inline FieldDescriptor::Type FieldDescriptor::type() const {
-  if (type_once_) {
-    absl::call_once(*type_once_, &FieldDescriptor::TypeOnceInit, this);
-  }
   return static_cast<Type>(type_);
 }
 
@@ -2896,7 +2893,7 @@ typename FieldOpts::CType EffectiveStringCType(const FieldDesc* field) {
 }
 
 #ifndef SWIG
-enum class Utf8CheckMode {
+enum class Utf8CheckMode : uint8_t {
   kStrict = 0,  // Parsing will fail if non UTF-8 data is in string fields.
   kVerify = 1,  // Only log an error but parsing will succeed.
   kNone = 2,    // No UTF-8 check.
diff --git a/src/google/protobuf/descriptor.pb.cc b/src/google/protobuf/descriptor.pb.cc
index ef5e9900ba..f5985f0056 100644
--- a/src/google/protobuf/descriptor.pb.cc
+++ b/src/google/protobuf/descriptor.pb.cc
@@ -1897,7 +1897,7 @@ const char descriptor_table_protodef_google_2fprotobuf_2fdescriptor_2eproto[] AB
     "ive_int_value\030\005 \001(\003\022\024\n\014double_value\030\006 \001("
     "\001\022\024\n\014string_value\030\007 \001(\014\022\027\n\017aggregate_val"
     "ue\030\010 \001(\t\0323\n\010NamePart\022\021\n\tname_part\030\001 \002(\t\022"
-    "\024\n\014is_extension\030\002 \002(\010\"\333\t\n\nFeatureSet\022\202\001\n"
+    "\024\n\014is_extension\030\002 \002(\010\"\303\t\n\nFeatureSet\022\202\001\n"
     "\016field_presence\030\001 \001(\0162).google.protobuf."
     "FeatureSet.FieldPresenceB\?\210\001\001\230\001\004\230\001\001\242\001\r\022\010"
     "EXPLICIT\030\346\007\242\001\r\022\010IMPLICIT\030\347\007\242\001\r\022\010EXPLICIT"
@@ -1927,47 +1927,47 @@ const char descriptor_table_protodef_google_2fprotobuf_2fdescriptor_2eproto[] AB
     "GE_ENCODING_UNKNOWN\020\000\022\023\n\017LENGTH_PREFIXED"
     "\020\001\022\r\n\tDELIMITED\020\002\"H\n\nJsonFormat\022\027\n\023JSON_"
     "FORMAT_UNKNOWN\020\000\022\t\n\005ALLOW\020\001\022\026\n\022LEGACY_BE"
-    "ST_EFFORT\020\002*\006\010\350\007\020\351\007*\006\010\351\007\020\352\007*\006\010\352\007\020\353\007*\006\010\206N"
-    "\020\207N*\006\010\213N\020\220N*\006\010\220N\020\221NJ\006\010\347\007\020\350\007\"\202\003\n\022FeatureS"
-    "etDefaults\022N\n\010defaults\030\001 \003(\0132<.google.pr"
-    "otobuf.FeatureSetDefaults.FeatureSetEdit"
-    "ionDefault\0221\n\017minimum_edition\030\004 \001(\0162\030.go"
-    "ogle.protobuf.Edition\0221\n\017maximum_edition"
-    "\030\005 \001(\0162\030.google.protobuf.Edition\032\265\001\n\030Fea"
-    "tureSetEditionDefault\022)\n\007edition\030\003 \001(\0162\030"
-    ".google.protobuf.Edition\0229\n\024overridable_"
-    "features\030\004 \001(\0132\033.google.protobuf.Feature"
-    "Set\0223\n\016fixed_features\030\005 \001(\0132\033.google.pro"
-    "tobuf.FeatureSet\"\325\001\n\016SourceCodeInfo\022:\n\010l"
-    "ocation\030\001 \003(\0132(.google.protobuf.SourceCo"
-    "deInfo.Location\032\206\001\n\010Location\022\020\n\004path\030\001 \003"
-    "(\005B\002\020\001\022\020\n\004span\030\002 \003(\005B\002\020\001\022\030\n\020leading_comm"
-    "ents\030\003 \001(\t\022\031\n\021trailing_comments\030\004 \001(\t\022!\n"
-    "\031leading_detached_comments\030\006 \003(\t\"\234\002\n\021Gen"
-    "eratedCodeInfo\022A\n\nannotation\030\001 \003(\0132-.goo"
-    "gle.protobuf.GeneratedCodeInfo.Annotatio"
-    "n\032\303\001\n\nAnnotation\022\020\n\004path\030\001 \003(\005B\002\020\001\022\023\n\013so"
-    "urce_file\030\002 \001(\t\022\r\n\005begin\030\003 \001(\005\022\013\n\003end\030\004 "
-    "\001(\005\022H\n\010semantic\030\005 \001(\01626.google.protobuf."
-    "GeneratedCodeInfo.Annotation.Semantic\"(\n"
-    "\010Semantic\022\010\n\004NONE\020\000\022\007\n\003SET\020\001\022\t\n\005ALIAS\020\002*"
-    "\247\002\n\007Edition\022\023\n\017EDITION_UNKNOWN\020\000\022\023\n\016EDIT"
-    "ION_LEGACY\020\204\007\022\023\n\016EDITION_PROTO2\020\346\007\022\023\n\016ED"
-    "ITION_PROTO3\020\347\007\022\021\n\014EDITION_2023\020\350\007\022\021\n\014ED"
-    "ITION_2024\020\351\007\022\027\n\023EDITION_1_TEST_ONLY\020\001\022\027"
-    "\n\023EDITION_2_TEST_ONLY\020\002\022\035\n\027EDITION_99997"
-    "_TEST_ONLY\020\235\215\006\022\035\n\027EDITION_99998_TEST_ONL"
-    "Y\020\236\215\006\022\035\n\027EDITION_99999_TEST_ONLY\020\237\215\006\022\023\n\013"
-    "EDITION_MAX\020\377\377\377\377\007B~\n\023com.google.protobuf"
-    "B\020DescriptorProtosH\001Z-google.golang.org/"
-    "protobuf/types/descriptorpb\370\001\001\242\002\003GPB\252\002\032G"
-    "oogle.Protobuf.Reflection"
+    "ST_EFFORT\020\002*\006\010\350\007\020\213N*\006\010\213N\020\220N*\006\010\220N\020\221NJ\006\010\347\007"
+    "\020\350\007\"\202\003\n\022FeatureSetDefaults\022N\n\010defaults\030\001"
+    " \003(\0132<.google.protobuf.FeatureSetDefault"
+    "s.FeatureSetEditionDefault\0221\n\017minimum_ed"
+    "ition\030\004 \001(\0162\030.google.protobuf.Edition\0221\n"
+    "\017maximum_edition\030\005 \001(\0162\030.google.protobuf"
+    ".Edition\032\265\001\n\030FeatureSetEditionDefault\022)\n"
+    "\007edition\030\003 \001(\0162\030.google.protobuf.Edition"
+    "\0229\n\024overridable_features\030\004 \001(\0132\033.google."
+    "protobuf.FeatureSet\0223\n\016fixed_features\030\005 "
+    "\001(\0132\033.google.protobuf.FeatureSet\"\325\001\n\016Sou"
+    "rceCodeInfo\022:\n\010location\030\001 \003(\0132(.google.p"
+    "rotobuf.SourceCodeInfo.Location\032\206\001\n\010Loca"
+    "tion\022\020\n\004path\030\001 \003(\005B\002\020\001\022\020\n\004span\030\002 \003(\005B\002\020\001"
+    "\022\030\n\020leading_comments\030\003 \001(\t\022\031\n\021trailing_c"
+    "omments\030\004 \001(\t\022!\n\031leading_detached_commen"
+    "ts\030\006 \003(\t\"\234\002\n\021GeneratedCodeInfo\022A\n\nannota"
+    "tion\030\001 \003(\0132-.google.protobuf.GeneratedCo"
+    "deInfo.Annotation\032\303\001\n\nAnnotation\022\020\n\004path"
+    "\030\001 \003(\005B\002\020\001\022\023\n\013source_file\030\002 \001(\t\022\r\n\005begin"
+    "\030\003 \001(\005\022\013\n\003end\030\004 \001(\005\022H\n\010semantic\030\005 \001(\01626."
+    "google.protobuf.GeneratedCodeInfo.Annota"
+    "tion.Semantic\"(\n\010Semantic\022\010\n\004NONE\020\000\022\007\n\003S"
+    "ET\020\001\022\t\n\005ALIAS\020\002*\247\002\n\007Edition\022\023\n\017EDITION_U"
+    "NKNOWN\020\000\022\023\n\016EDITION_LEGACY\020\204\007\022\023\n\016EDITION"
+    "_PROTO2\020\346\007\022\023\n\016EDITION_PROTO3\020\347\007\022\021\n\014EDITI"
+    "ON_2023\020\350\007\022\021\n\014EDITION_2024\020\351\007\022\027\n\023EDITION"
+    "_1_TEST_ONLY\020\001\022\027\n\023EDITION_2_TEST_ONLY\020\002\022"
+    "\035\n\027EDITION_99997_TEST_ONLY\020\235\215\006\022\035\n\027EDITIO"
+    "N_99998_TEST_ONLY\020\236\215\006\022\035\n\027EDITION_99999_T"
+    "EST_ONLY\020\237\215\006\022\023\n\013EDITION_MAX\020\377\377\377\377\007B~\n\023com"
+    ".google.protobufB\020DescriptorProtosH\001Z-go"
+    "ogle.golang.org/protobuf/types/descripto"
+    "rpb\370\001\001\242\002\003GPB\252\002\032Google.Protobuf.Reflectio"
+    "n"
 };
 static ::absl::once_flag descriptor_table_google_2fprotobuf_2fdescriptor_2eproto_once;
 PROTOBUF_CONSTINIT const ::_pbi::DescriptorTable descriptor_table_google_2fprotobuf_2fdescriptor_2eproto = {
     false,
     false,
-    9985,
+    9961,
     descriptor_table_protodef_google_2fprotobuf_2fdescriptor_2eproto,
     "google/protobuf/descriptor.proto",
     &descriptor_table_google_2fprotobuf_2fdescriptor_2eproto_once,
@@ -2535,18 +2535,23 @@ PROTOBUF_NOINLINE void FileDescriptorSet::Clear() {
 }
 
 ::size_t FileDescriptorSet::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FileDescriptorSet)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FileDescriptorSet)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.FileDescriptorProto file = 1;
-  total_size += 1UL * this->_internal_file_size();
-  for (const auto& msg : this->_internal_file()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.FileDescriptorProto file = 1;
+     {
+      total_size += 1UL * this->_internal_file_size();
+      for (const auto& msg : this->_internal_file()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -2985,59 +2990,72 @@ PROTOBUF_NOINLINE void FileDescriptorProto::Clear() {
 }
 
 ::size_t FileDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FileDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FileDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated string dependency = 3;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_dependency().size());
-  for (int i = 0, n = _internal_dependency().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_dependency().Get(i));
-  }
-  // repeated .google.protobuf.DescriptorProto message_type = 4;
-  total_size += 1UL * this->_internal_message_type_size();
-  for (const auto& msg : this->_internal_message_type()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
-  total_size += 1UL * this->_internal_enum_type_size();
-  for (const auto& msg : this->_internal_enum_type()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.ServiceDescriptorProto service = 6;
-  total_size += 1UL * this->_internal_service_size();
-  for (const auto& msg : this->_internal_service()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.FieldDescriptorProto extension = 7;
-  total_size += 1UL * this->_internal_extension_size();
-  for (const auto& msg : this->_internal_extension()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated int32 public_dependency = 10;
-  {
-    std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
-        this->_internal_public_dependency())
-    ;
-    std::size_t tag_size = std::size_t{1} *
-        ::_pbi::FromIntSize(this->_internal_public_dependency_size());
-    ;
-    total_size += tag_size + data_size;
-  }
-  // repeated int32 weak_dependency = 11;
-  {
-    std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
-        this->_internal_weak_dependency())
-    ;
-    std::size_t tag_size = std::size_t{1} *
-        ::_pbi::FromIntSize(this->_internal_weak_dependency_size());
-    ;
-    total_size += tag_size + data_size;
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated string dependency = 3;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_dependency().size());
+      for (int i = 0, n = _internal_dependency().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_dependency().Get(i));
+      }
+    }
+    // repeated .google.protobuf.DescriptorProto message_type = 4;
+     {
+      total_size += 1UL * this->_internal_message_type_size();
+      for (const auto& msg : this->_internal_message_type()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.EnumDescriptorProto enum_type = 5;
+     {
+      total_size += 1UL * this->_internal_enum_type_size();
+      for (const auto& msg : this->_internal_enum_type()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.ServiceDescriptorProto service = 6;
+     {
+      total_size += 1UL * this->_internal_service_size();
+      for (const auto& msg : this->_internal_service()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.FieldDescriptorProto extension = 7;
+     {
+      total_size += 1UL * this->_internal_extension_size();
+      for (const auto& msg : this->_internal_extension()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated int32 public_dependency = 10;
+     {
+      std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
+          this->_internal_public_dependency())
+      ;
+      std::size_t tag_size = std::size_t{1} *
+          ::_pbi::FromIntSize(this->_internal_public_dependency_size());
+      ;
+      total_size += tag_size + data_size;
+    }
+    // repeated int32 weak_dependency = 11;
+     {
+      std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
+          this->_internal_weak_dependency())
+      ;
+      std::size_t tag_size = std::size_t{1} *
+          ::_pbi::FromIntSize(this->_internal_weak_dependency_size());
+      ;
+      total_size += tag_size + data_size;
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000003fu) {
@@ -3046,37 +3064,31 @@ PROTOBUF_NOINLINE void FileDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional string package = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_package());
     }
-
     // optional string syntax = 12;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_syntax());
     }
-
     // optional .google.protobuf.FileOptions options = 8;
     if (cached_has_bits & 0x00000008u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
     // optional .google.protobuf.SourceCodeInfo source_code_info = 9;
     if (cached_has_bits & 0x00000010u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_code_info_);
     }
-
     // optional .google.protobuf.Edition edition = 14;
     if (cached_has_bits & 0x00000020u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_edition());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -3384,14 +3396,15 @@ PROTOBUF_NOINLINE void DescriptorProto_ExtensionRange::Clear() {
 }
 
 ::size_t DescriptorProto_ExtensionRange::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.DescriptorProto.ExtensionRange)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.DescriptorProto.ExtensionRange)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000007u) {
     // optional .google.protobuf.ExtensionRangeOptions options = 3;
@@ -3399,19 +3412,16 @@ PROTOBUF_NOINLINE void DescriptorProto_ExtensionRange::Clear() {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
     // optional int32 start = 1;
     if (cached_has_bits & 0x00000002u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_start());
     }
-
     // optional int32 end = 2;
     if (cached_has_bits & 0x00000004u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_end());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -3631,14 +3641,15 @@ PROTOBUF_NOINLINE void DescriptorProto_ReservedRange::Clear() {
 }
 
 ::size_t DescriptorProto_ReservedRange::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.DescriptorProto.ReservedRange)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.DescriptorProto.ReservedRange)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // optional int32 start = 1;
@@ -3646,13 +3657,11 @@ PROTOBUF_NOINLINE void DescriptorProto_ReservedRange::Clear() {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_start());
     }
-
     // optional int32 end = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_end());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -4048,54 +4057,73 @@ PROTOBUF_NOINLINE void DescriptorProto::Clear() {
 }
 
 ::size_t DescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.DescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.DescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.FieldDescriptorProto field = 2;
-  total_size += 1UL * this->_internal_field_size();
-  for (const auto& msg : this->_internal_field()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.DescriptorProto nested_type = 3;
-  total_size += 1UL * this->_internal_nested_type_size();
-  for (const auto& msg : this->_internal_nested_type()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
-  total_size += 1UL * this->_internal_enum_type_size();
-  for (const auto& msg : this->_internal_enum_type()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
-  total_size += 1UL * this->_internal_extension_range_size();
-  for (const auto& msg : this->_internal_extension_range()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.FieldDescriptorProto extension = 6;
-  total_size += 1UL * this->_internal_extension_size();
-  for (const auto& msg : this->_internal_extension()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.OneofDescriptorProto oneof_decl = 8;
-  total_size += 1UL * this->_internal_oneof_decl_size();
-  for (const auto& msg : this->_internal_oneof_decl()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.DescriptorProto.ReservedRange reserved_range = 9;
-  total_size += 1UL * this->_internal_reserved_range_size();
-  for (const auto& msg : this->_internal_reserved_range()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated string reserved_name = 10;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_reserved_name().size());
-  for (int i = 0, n = _internal_reserved_name().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_reserved_name().Get(i));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.FieldDescriptorProto field = 2;
+     {
+      total_size += 1UL * this->_internal_field_size();
+      for (const auto& msg : this->_internal_field()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.DescriptorProto nested_type = 3;
+     {
+      total_size += 1UL * this->_internal_nested_type_size();
+      for (const auto& msg : this->_internal_nested_type()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.EnumDescriptorProto enum_type = 4;
+     {
+      total_size += 1UL * this->_internal_enum_type_size();
+      for (const auto& msg : this->_internal_enum_type()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.DescriptorProto.ExtensionRange extension_range = 5;
+     {
+      total_size += 1UL * this->_internal_extension_range_size();
+      for (const auto& msg : this->_internal_extension_range()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.FieldDescriptorProto extension = 6;
+     {
+      total_size += 1UL * this->_internal_extension_size();
+      for (const auto& msg : this->_internal_extension()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.OneofDescriptorProto oneof_decl = 8;
+     {
+      total_size += 1UL * this->_internal_oneof_decl_size();
+      for (const auto& msg : this->_internal_oneof_decl()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.DescriptorProto.ReservedRange reserved_range = 9;
+     {
+      total_size += 1UL * this->_internal_reserved_range_size();
+      for (const auto& msg : this->_internal_reserved_range()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated string reserved_name = 10;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_reserved_name().size());
+      for (int i = 0, n = _internal_reserved_name().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_reserved_name().Get(i));
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -4104,13 +4132,11 @@ PROTOBUF_NOINLINE void DescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional .google.protobuf.MessageOptions options = 7;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -4442,14 +4468,15 @@ PROTOBUF_NOINLINE void ExtensionRangeOptions_Declaration::Clear() {
 }
 
 ::size_t ExtensionRangeOptions_Declaration::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.ExtensionRangeOptions.Declaration)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.ExtensionRangeOptions.Declaration)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000001fu) {
     // optional string full_name = 2;
@@ -4457,29 +4484,24 @@ PROTOBUF_NOINLINE void ExtensionRangeOptions_Declaration::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_full_name());
     }
-
     // optional string type = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_type());
     }
-
     // optional int32 number = 1;
     if (cached_has_bits & 0x00000004u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_number());
     }
-
     // optional bool reserved = 5;
     if (cached_has_bits & 0x00000008u) {
       total_size += 2;
     }
-
     // optional bool repeated = 6;
     if (cached_has_bits & 0x00000010u) {
       total_size += 2;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -4765,25 +4787,31 @@ PROTOBUF_NOINLINE void ExtensionRangeOptions::Clear() {
 }
 
 ::size_t ExtensionRangeOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.ExtensionRangeOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.ExtensionRangeOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.ExtensionRangeOptions.Declaration declaration = 2 [retention = RETENTION_SOURCE];
-  total_size += 1UL * this->_internal_declaration_size();
-  for (const auto& msg : this->_internal_declaration()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.ExtensionRangeOptions.Declaration declaration = 2 [retention = RETENTION_SOURCE];
+     {
+      total_size += 1UL * this->_internal_declaration_size();
+      for (const auto& msg : this->_internal_declaration()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -4792,13 +4820,11 @@ PROTOBUF_NOINLINE void ExtensionRangeOptions::Clear() {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional .google.protobuf.ExtensionRangeOptions.VerificationState verification = 3 [default = UNVERIFIED, retention = RETENTION_SOURCE];
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_verification());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -5230,14 +5256,15 @@ PROTOBUF_NOINLINE void FieldDescriptorProto::Clear() {
 }
 
 ::size_t FieldDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x000000ffu) {
     // optional string name = 1;
@@ -5245,68 +5272,57 @@ PROTOBUF_NOINLINE void FieldDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional string extendee = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_extendee());
     }
-
     // optional string type_name = 6;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_type_name());
     }
-
     // optional string default_value = 7;
     if (cached_has_bits & 0x00000008u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_default_value());
     }
-
     // optional string json_name = 10;
     if (cached_has_bits & 0x00000010u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_json_name());
     }
-
     // optional .google.protobuf.FieldOptions options = 8;
     if (cached_has_bits & 0x00000020u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
     // optional int32 number = 3;
     if (cached_has_bits & 0x00000040u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_number());
     }
-
     // optional int32 oneof_index = 9;
     if (cached_has_bits & 0x00000080u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_oneof_index());
     }
-
   }
   if (cached_has_bits & 0x00000700u) {
     // optional bool proto3_optional = 17;
     if (cached_has_bits & 0x00000100u) {
       total_size += 3;
     }
-
     // optional .google.protobuf.FieldDescriptorProto.Label label = 4;
     if (cached_has_bits & 0x00000200u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_label());
     }
-
     // optional .google.protobuf.FieldDescriptorProto.Type type = 5;
     if (cached_has_bits & 0x00000400u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_type());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -5582,14 +5598,15 @@ PROTOBUF_NOINLINE void OneofDescriptorProto::Clear() {
 }
 
 ::size_t OneofDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.OneofDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.OneofDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // optional string name = 1;
@@ -5597,13 +5614,11 @@ PROTOBUF_NOINLINE void OneofDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional .google.protobuf.OneofOptions options = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -5818,14 +5833,15 @@ PROTOBUF_NOINLINE void EnumDescriptorProto_EnumReservedRange::Clear() {
 }
 
 ::size_t EnumDescriptorProto_EnumReservedRange::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumDescriptorProto.EnumReservedRange)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumDescriptorProto.EnumReservedRange)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // optional int32 start = 1;
@@ -5833,13 +5849,11 @@ PROTOBUF_NOINLINE void EnumDescriptorProto_EnumReservedRange::Clear() {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_start());
     }
-
     // optional int32 end = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_end());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -6127,29 +6141,38 @@ PROTOBUF_NOINLINE void EnumDescriptorProto::Clear() {
 }
 
 ::size_t EnumDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
-  total_size += 1UL * this->_internal_value_size();
-  for (const auto& msg : this->_internal_value()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.EnumDescriptorProto.EnumReservedRange reserved_range = 4;
-  total_size += 1UL * this->_internal_reserved_range_size();
-  for (const auto& msg : this->_internal_reserved_range()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated string reserved_name = 5;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_reserved_name().size());
-  for (int i = 0, n = _internal_reserved_name().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_reserved_name().Get(i));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.EnumValueDescriptorProto value = 2;
+     {
+      total_size += 1UL * this->_internal_value_size();
+      for (const auto& msg : this->_internal_value()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.EnumDescriptorProto.EnumReservedRange reserved_range = 4;
+     {
+      total_size += 1UL * this->_internal_reserved_range_size();
+      for (const auto& msg : this->_internal_reserved_range()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated string reserved_name = 5;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_reserved_name().size());
+      for (int i = 0, n = _internal_reserved_name().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_reserved_name().Get(i));
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -6158,13 +6181,11 @@ PROTOBUF_NOINLINE void EnumDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional .google.protobuf.EnumOptions options = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -6433,14 +6454,15 @@ PROTOBUF_NOINLINE void EnumValueDescriptorProto::Clear() {
 }
 
 ::size_t EnumValueDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumValueDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumValueDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000007u) {
     // optional string name = 1;
@@ -6448,19 +6470,16 @@ PROTOBUF_NOINLINE void EnumValueDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional .google.protobuf.EnumValueOptions options = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
     // optional int32 number = 2;
     if (cached_has_bits & 0x00000004u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_number());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -6728,18 +6747,23 @@ PROTOBUF_NOINLINE void ServiceDescriptorProto::Clear() {
 }
 
 ::size_t ServiceDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.ServiceDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.ServiceDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.MethodDescriptorProto method = 2;
-  total_size += 1UL * this->_internal_method_size();
-  for (const auto& msg : this->_internal_method()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.MethodDescriptorProto method = 2;
+     {
+      total_size += 1UL * this->_internal_method_size();
+      for (const auto& msg : this->_internal_method()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -6748,13 +6772,11 @@ PROTOBUF_NOINLINE void ServiceDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional .google.protobuf.ServiceOptions options = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -7082,14 +7104,15 @@ PROTOBUF_NOINLINE void MethodDescriptorProto::Clear() {
 }
 
 ::size_t MethodDescriptorProto::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.MethodDescriptorProto)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.MethodDescriptorProto)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000003fu) {
     // optional string name = 1;
@@ -7097,35 +7120,29 @@ PROTOBUF_NOINLINE void MethodDescriptorProto::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name());
     }
-
     // optional string input_type = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_input_type());
     }
-
     // optional string output_type = 3;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_output_type());
     }
-
     // optional .google.protobuf.MethodOptions options = 4;
     if (cached_has_bits & 0x00000008u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.options_);
     }
-
     // optional bool client_streaming = 5 [default = false];
     if (cached_has_bits & 0x00000010u) {
       total_size += 2;
     }
-
     // optional bool server_streaming = 6 [default = false];
     if (cached_has_bits & 0x00000020u) {
       total_size += 2;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -7751,20 +7768,24 @@ PROTOBUF_NOINLINE void FileOptions::Clear() {
 }
 
 ::size_t FileOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FileOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FileOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x000000ffu) {
@@ -7773,49 +7794,41 @@ PROTOBUF_NOINLINE void FileOptions::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_java_package());
     }
-
     // optional string java_outer_classname = 8;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_java_outer_classname());
     }
-
     // optional string go_package = 11;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_go_package());
     }
-
     // optional string objc_class_prefix = 36;
     if (cached_has_bits & 0x00000008u) {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_objc_class_prefix());
     }
-
     // optional string csharp_namespace = 37;
     if (cached_has_bits & 0x00000010u) {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_csharp_namespace());
     }
-
     // optional string swift_prefix = 39;
     if (cached_has_bits & 0x00000020u) {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_swift_prefix());
     }
-
     // optional string php_class_prefix = 40;
     if (cached_has_bits & 0x00000040u) {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_php_class_prefix());
     }
-
     // optional string php_namespace = 41;
     if (cached_has_bits & 0x00000080u) {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_php_namespace());
     }
-
   }
   if (cached_has_bits & 0x0000ff00u) {
     // optional string php_metadata_namespace = 44;
@@ -7823,67 +7836,55 @@ PROTOBUF_NOINLINE void FileOptions::Clear() {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_php_metadata_namespace());
     }
-
     // optional string ruby_package = 45;
     if (cached_has_bits & 0x00000200u) {
       total_size += 2 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_ruby_package());
     }
-
     // optional .google.protobuf.FeatureSet features = 50;
     if (cached_has_bits & 0x00000400u) {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional bool java_multiple_files = 10 [default = false];
     if (cached_has_bits & 0x00000800u) {
       total_size += 2;
     }
-
     // optional bool java_generate_equals_and_hash = 20 [deprecated = true];
     if (cached_has_bits & 0x00001000u) {
       total_size += 3;
     }
-
     // optional bool java_string_check_utf8 = 27 [default = false];
     if (cached_has_bits & 0x00002000u) {
       total_size += 3;
     }
-
     // optional bool cc_generic_services = 16 [default = false];
     if (cached_has_bits & 0x00004000u) {
       total_size += 3;
     }
-
     // optional bool java_generic_services = 17 [default = false];
     if (cached_has_bits & 0x00008000u) {
       total_size += 3;
     }
-
   }
   if (cached_has_bits & 0x000f0000u) {
     // optional bool py_generic_services = 18 [default = false];
     if (cached_has_bits & 0x00010000u) {
       total_size += 3;
     }
-
     // optional bool deprecated = 23 [default = false];
     if (cached_has_bits & 0x00020000u) {
       total_size += 3;
     }
-
     // optional .google.protobuf.FileOptions.OptimizeMode optimize_for = 9 [default = SPEED];
     if (cached_has_bits & 0x00040000u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_optimize_for());
     }
-
     // optional bool cc_enable_arenas = 31 [default = true];
     if (cached_has_bits & 0x00080000u) {
       total_size += 3;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -8288,20 +8289,24 @@ PROTOBUF_NOINLINE void MessageOptions::Clear() {
 }
 
 ::size_t MessageOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.MessageOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.MessageOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000003fu) {
@@ -8310,32 +8315,26 @@ PROTOBUF_NOINLINE void MessageOptions::Clear() {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional bool message_set_wire_format = 1 [default = false];
     if (cached_has_bits & 0x00000002u) {
       total_size += 2;
     }
-
     // optional bool no_standard_descriptor_accessor = 2 [default = false];
     if (cached_has_bits & 0x00000004u) {
       total_size += 2;
     }
-
     // optional bool deprecated = 3 [default = false];
     if (cached_has_bits & 0x00000008u) {
       total_size += 2;
     }
-
     // optional bool map_entry = 7;
     if (cached_has_bits & 0x00000010u) {
       total_size += 2;
     }
-
     // optional bool deprecated_legacy_json_field_conflicts = 11 [deprecated = true];
     if (cached_has_bits & 0x00000020u) {
       total_size += 2;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -8590,14 +8589,15 @@ PROTOBUF_NOINLINE void FieldOptions_EditionDefault::Clear() {
 }
 
 ::size_t FieldOptions_EditionDefault::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldOptions.EditionDefault)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldOptions.EditionDefault)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // optional string value = 2;
@@ -8605,13 +8605,11 @@ PROTOBUF_NOINLINE void FieldOptions_EditionDefault::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_value());
     }
-
     // optional .google.protobuf.Edition edition = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_edition());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -8869,14 +8867,15 @@ PROTOBUF_NOINLINE void FieldOptions_FeatureSupport::Clear() {
 }
 
 ::size_t FieldOptions_FeatureSupport::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldOptions.FeatureSupport)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldOptions.FeatureSupport)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000000fu) {
     // optional string deprecation_warning = 3;
@@ -8884,25 +8883,21 @@ PROTOBUF_NOINLINE void FieldOptions_FeatureSupport::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_deprecation_warning());
     }
-
     // optional .google.protobuf.Edition edition_introduced = 1;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_edition_introduced());
     }
-
     // optional .google.protobuf.Edition edition_deprecated = 2;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_edition_deprecated());
     }
-
     // optional .google.protobuf.Edition edition_removed = 4;
     if (cached_has_bits & 0x00000008u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_edition_removed());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -9339,37 +9334,43 @@ PROTOBUF_NOINLINE void FieldOptions::Clear() {
 }
 
 ::size_t FieldOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.FieldOptions.OptionTargetType targets = 19;
-  {
-    std::size_t data_size = 0;
-    auto count = static_cast<std::size_t>(this->_internal_targets_size());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.FieldOptions.OptionTargetType targets = 19;
+     {
+      std::size_t data_size = 0;
+      auto count = static_cast<std::size_t>(this->_internal_targets_size());
 
-    for (std::size_t i = 0; i < count; ++i) {
-      data_size += ::_pbi::WireFormatLite::EnumSize(
-          this->_internal_targets().Get(static_cast<int>(i)));
+      for (std::size_t i = 0; i < count; ++i) {
+        data_size += ::_pbi::WireFormatLite::EnumSize(
+            this->_internal_targets().Get(static_cast<int>(i)));
+      }
+      total_size += data_size;
+      total_size += std::size_t{2} * count;
+    }
+    // repeated .google.protobuf.FieldOptions.EditionDefault edition_defaults = 20;
+     {
+      total_size += 2UL * this->_internal_edition_defaults_size();
+      for (const auto& msg : this->_internal_edition_defaults()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
     }
-    total_size += data_size;
-    total_size += std::size_t{2} * count;
-  }
-  // repeated .google.protobuf.FieldOptions.EditionDefault edition_defaults = 20;
-  total_size += 2UL * this->_internal_edition_defaults_size();
-  for (const auto& msg : this->_internal_edition_defaults()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x000000ffu) {
@@ -9378,63 +9379,52 @@ PROTOBUF_NOINLINE void FieldOptions::Clear() {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional .google.protobuf.FieldOptions.FeatureSupport feature_support = 22;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.feature_support_);
     }
-
     // optional .google.protobuf.FieldOptions.CType ctype = 1 [default = STRING];
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_ctype());
     }
-
     // optional .google.protobuf.FieldOptions.JSType jstype = 6 [default = JS_NORMAL];
     if (cached_has_bits & 0x00000008u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_jstype());
     }
-
     // optional bool packed = 2;
     if (cached_has_bits & 0x00000010u) {
       total_size += 2;
     }
-
     // optional bool lazy = 5 [default = false];
     if (cached_has_bits & 0x00000020u) {
       total_size += 2;
     }
-
     // optional bool unverified_lazy = 15 [default = false];
     if (cached_has_bits & 0x00000040u) {
       total_size += 2;
     }
-
     // optional bool deprecated = 3 [default = false];
     if (cached_has_bits & 0x00000080u) {
       total_size += 2;
     }
-
   }
   if (cached_has_bits & 0x00000700u) {
     // optional bool weak = 10 [default = false];
     if (cached_has_bits & 0x00000100u) {
       total_size += 2;
     }
-
     // optional bool debug_redact = 16 [default = false];
     if (cached_has_bits & 0x00000200u) {
       total_size += 3;
     }
-
     // optional .google.protobuf.FieldOptions.OptionRetention retention = 17;
     if (cached_has_bits & 0x00000400u) {
       total_size += 2 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_retention());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -9732,28 +9722,33 @@ PROTOBUF_NOINLINE void OneofOptions::Clear() {
 }
 
 ::size_t OneofOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.OneofOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.OneofOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-  // optional .google.protobuf.FeatureSet features = 1;
-  cached_has_bits = _impl_._has_bits_[0];
-  if (cached_has_bits & 0x00000001u) {
-    total_size +=
-        1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
+   {
+    // optional .google.protobuf.FeatureSet features = 1;
+    cached_has_bits = _impl_._has_bits_[0];
+    if (cached_has_bits & 0x00000001u) {
+      total_size +=
+          1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -10053,20 +10048,24 @@ PROTOBUF_NOINLINE void EnumOptions::Clear() {
 }
 
 ::size_t EnumOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000000fu) {
@@ -10075,22 +10074,18 @@ PROTOBUF_NOINLINE void EnumOptions::Clear() {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional bool allow_alias = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += 2;
     }
-
     // optional bool deprecated = 3 [default = false];
     if (cached_has_bits & 0x00000004u) {
       total_size += 2;
     }
-
     // optional bool deprecated_legacy_json_field_conflicts = 6 [deprecated = true];
     if (cached_has_bits & 0x00000008u) {
       total_size += 2;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -10397,20 +10392,24 @@ PROTOBUF_NOINLINE void EnumValueOptions::Clear() {
 }
 
 ::size_t EnumValueOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumValueOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumValueOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000007u) {
@@ -10419,17 +10418,14 @@ PROTOBUF_NOINLINE void EnumValueOptions::Clear() {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional bool deprecated = 1 [default = false];
     if (cached_has_bits & 0x00000002u) {
       total_size += 2;
     }
-
     // optional bool debug_redact = 3 [default = false];
     if (cached_has_bits & 0x00000004u) {
       total_size += 2;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -10710,20 +10706,24 @@ PROTOBUF_NOINLINE void ServiceOptions::Clear() {
 }
 
 ::size_t ServiceOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.ServiceOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.ServiceOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -10732,12 +10732,10 @@ PROTOBUF_NOINLINE void ServiceOptions::Clear() {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional bool deprecated = 33 [default = false];
     if (cached_has_bits & 0x00000002u) {
       total_size += 3;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -11042,20 +11040,24 @@ PROTOBUF_NOINLINE void MethodOptions::Clear() {
 }
 
 ::size_t MethodOptions::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.MethodOptions)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.MethodOptions)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
-  total_size += 2UL * this->_internal_uninterpreted_option_size();
-  for (const auto& msg : this->_internal_uninterpreted_option()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption uninterpreted_option = 999;
+     {
+      total_size += 2UL * this->_internal_uninterpreted_option_size();
+      for (const auto& msg : this->_internal_uninterpreted_option()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000007u) {
@@ -11064,18 +11066,15 @@ PROTOBUF_NOINLINE void MethodOptions::Clear() {
       total_size +=
           2 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.features_);
     }
-
     // optional bool deprecated = 33 [default = false];
     if (cached_has_bits & 0x00000002u) {
       total_size += 3;
     }
-
     // optional .google.protobuf.MethodOptions.IdempotencyLevel idempotency_level = 34 [default = IDEMPOTENCY_UNKNOWN];
     if (cached_has_bits & 0x00000004u) {
       total_size += 2 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_idempotency_level());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -11324,14 +11323,15 @@ PROTOBUF_NOINLINE void UninterpretedOption_NamePart::Clear() {
 }
 
 ::size_t UninterpretedOption_NamePart::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.UninterpretedOption.NamePart)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.UninterpretedOption.NamePart)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
     // required string name_part = 1;
@@ -11339,12 +11339,10 @@ PROTOBUF_NOINLINE void UninterpretedOption_NamePart::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_name_part());
     }
-
     // required bool is_extension = 2;
     if (cached_has_bits & 0x00000002u) {
       total_size += 2;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -11670,18 +11668,23 @@ PROTOBUF_NOINLINE void UninterpretedOption::Clear() {
 }
 
 ::size_t UninterpretedOption::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.UninterpretedOption)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.UninterpretedOption)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.UninterpretedOption.NamePart name = 2;
-  total_size += 1UL * this->_internal_name_size();
-  for (const auto& msg : this->_internal_name()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.UninterpretedOption.NamePart name = 2;
+     {
+      total_size += 1UL * this->_internal_name_size();
+      for (const auto& msg : this->_internal_name()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000003fu) {
@@ -11690,36 +11693,30 @@ PROTOBUF_NOINLINE void UninterpretedOption::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_identifier_value());
     }
-
     // optional bytes string_value = 7;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::BytesSize(
                                       this->_internal_string_value());
     }
-
     // optional string aggregate_value = 8;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_aggregate_value());
     }
-
     // optional uint64 positive_int_value = 4;
     if (cached_has_bits & 0x00000008u) {
       total_size += ::_pbi::WireFormatLite::UInt64SizePlusOne(
           this->_internal_positive_int_value());
     }
-
     // optional int64 negative_int_value = 5;
     if (cached_has_bits & 0x00000010u) {
       total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
           this->_internal_negative_int_value());
     }
-
     // optional double double_value = 6;
     if (cached_has_bits & 0x00000020u) {
       total_size += 9;
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -12034,16 +12031,16 @@ PROTOBUF_NOINLINE void FeatureSet::Clear() {
 }
 
 ::size_t FeatureSet::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FeatureSet)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FeatureSet)
   ::size_t total_size = 0;
-
   total_size += _impl_._extensions_.ByteSize();
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000003fu) {
     // optional .google.protobuf.FeatureSet.FieldPresence field_presence = 1 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
@@ -12051,37 +12048,31 @@ PROTOBUF_NOINLINE void FeatureSet::Clear() {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_field_presence());
     }
-
     // optional .google.protobuf.FeatureSet.EnumType enum_type = 2 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_ENUM, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_enum_type());
     }
-
     // optional .google.protobuf.FeatureSet.RepeatedFieldEncoding repeated_field_encoding = 3 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_repeated_field_encoding());
     }
-
     // optional .google.protobuf.FeatureSet.Utf8Validation utf8_validation = 4 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000008u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_utf8_validation());
     }
-
     // optional .google.protobuf.FeatureSet.MessageEncoding message_encoding = 5 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_FIELD, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000010u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_message_encoding());
     }
-
     // optional .google.protobuf.FeatureSet.JsonFormat json_format = 6 [retention = RETENTION_RUNTIME, targets = TARGET_TYPE_MESSAGE, targets = TARGET_TYPE_ENUM, targets = TARGET_TYPE_FILE, edition_defaults = {
     if (cached_has_bits & 0x00000020u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_json_format());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -12349,14 +12340,15 @@ PROTOBUF_NOINLINE void FeatureSetDefaults_FeatureSetEditionDefault::Clear() {
 }
 
 ::size_t FeatureSetDefaults_FeatureSetEditionDefault::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FeatureSetDefaults.FeatureSetEditionDefault)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FeatureSetDefaults.FeatureSetEditionDefault)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000007u) {
     // optional .google.protobuf.FeatureSet overridable_features = 4;
@@ -12364,19 +12356,16 @@ PROTOBUF_NOINLINE void FeatureSetDefaults_FeatureSetEditionDefault::Clear() {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.overridable_features_);
     }
-
     // optional .google.protobuf.FeatureSet fixed_features = 5;
     if (cached_has_bits & 0x00000002u) {
       total_size +=
           1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.fixed_features_);
     }
-
     // optional .google.protobuf.Edition edition = 3;
     if (cached_has_bits & 0x00000004u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_edition());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -12644,18 +12633,23 @@ PROTOBUF_NOINLINE void FeatureSetDefaults::Clear() {
 }
 
 ::size_t FeatureSetDefaults::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FeatureSetDefaults)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FeatureSetDefaults)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.FeatureSetDefaults.FeatureSetEditionDefault defaults = 1;
-  total_size += 1UL * this->_internal_defaults_size();
-  for (const auto& msg : this->_internal_defaults()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.FeatureSetDefaults.FeatureSetEditionDefault defaults = 1;
+     {
+      total_size += 1UL * this->_internal_defaults_size();
+      for (const auto& msg : this->_internal_defaults()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -12664,13 +12658,11 @@ PROTOBUF_NOINLINE void FeatureSetDefaults::Clear() {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_minimum_edition());
     }
-
     // optional .google.protobuf.Edition maximum_edition = 5;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_maximum_edition());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -12965,45 +12957,50 @@ PROTOBUF_NOINLINE void SourceCodeInfo_Location::Clear() {
 }
 
 ::size_t SourceCodeInfo_Location::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.SourceCodeInfo.Location)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.SourceCodeInfo.Location)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated int32 path = 1 [packed = true];
-  {
-    std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
-        this->_internal_path())
-    ;
-    _impl_._path_cached_byte_size_.Set(::_pbi::ToCachedSize(data_size));
-    std::size_t tag_size = data_size == 0
-        ? 0
-        : 1 + ::_pbi::WireFormatLite::Int32Size(
-                            static_cast<int32_t>(data_size))
-    ;
-    total_size += tag_size + data_size;
-  }
-  // repeated int32 span = 2 [packed = true];
-  {
-    std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
-        this->_internal_span())
-    ;
-    _impl_._span_cached_byte_size_.Set(::_pbi::ToCachedSize(data_size));
-    std::size_t tag_size = data_size == 0
-        ? 0
-        : 1 + ::_pbi::WireFormatLite::Int32Size(
-                            static_cast<int32_t>(data_size))
-    ;
-    total_size += tag_size + data_size;
-  }
-  // repeated string leading_detached_comments = 6;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_leading_detached_comments().size());
-  for (int i = 0, n = _internal_leading_detached_comments().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_leading_detached_comments().Get(i));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated int32 path = 1 [packed = true];
+     {
+      std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
+          this->_internal_path())
+      ;
+      _impl_._path_cached_byte_size_.Set(::_pbi::ToCachedSize(data_size));
+      std::size_t tag_size = data_size == 0
+          ? 0
+          : 1 + ::_pbi::WireFormatLite::Int32Size(
+                              static_cast<int32_t>(data_size))
+      ;
+      total_size += tag_size + data_size;
+    }
+    // repeated int32 span = 2 [packed = true];
+     {
+      std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
+          this->_internal_span())
+      ;
+      _impl_._span_cached_byte_size_.Set(::_pbi::ToCachedSize(data_size));
+      std::size_t tag_size = data_size == 0
+          ? 0
+          : 1 + ::_pbi::WireFormatLite::Int32Size(
+                              static_cast<int32_t>(data_size))
+      ;
+      total_size += tag_size + data_size;
+    }
+    // repeated string leading_detached_comments = 6;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_leading_detached_comments().size());
+      for (int i = 0, n = _internal_leading_detached_comments().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_leading_detached_comments().Get(i));
+      }
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x00000003u) {
@@ -13012,13 +13009,11 @@ PROTOBUF_NOINLINE void SourceCodeInfo_Location::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_leading_comments());
     }
-
     // optional string trailing_comments = 4;
     if (cached_has_bits & 0x00000002u) {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_trailing_comments());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -13212,18 +13207,23 @@ PROTOBUF_NOINLINE void SourceCodeInfo::Clear() {
 }
 
 ::size_t SourceCodeInfo::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.SourceCodeInfo)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.SourceCodeInfo)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.SourceCodeInfo.Location location = 1;
-  total_size += 1UL * this->_internal_location_size();
-  for (const auto& msg : this->_internal_location()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.SourceCodeInfo.Location location = 1;
+     {
+      total_size += 1UL * this->_internal_location_size();
+      for (const auto& msg : this->_internal_location()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -13490,26 +13490,29 @@ PROTOBUF_NOINLINE void GeneratedCodeInfo_Annotation::Clear() {
 }
 
 ::size_t GeneratedCodeInfo_Annotation::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.GeneratedCodeInfo.Annotation)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.GeneratedCodeInfo.Annotation)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated int32 path = 1 [packed = true];
-  {
-    std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
-        this->_internal_path())
-    ;
-    _impl_._path_cached_byte_size_.Set(::_pbi::ToCachedSize(data_size));
-    std::size_t tag_size = data_size == 0
-        ? 0
-        : 1 + ::_pbi::WireFormatLite::Int32Size(
-                            static_cast<int32_t>(data_size))
-    ;
-    total_size += tag_size + data_size;
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated int32 path = 1 [packed = true];
+     {
+      std::size_t data_size = ::_pbi::WireFormatLite::Int32Size(
+          this->_internal_path())
+      ;
+      _impl_._path_cached_byte_size_.Set(::_pbi::ToCachedSize(data_size));
+      std::size_t tag_size = data_size == 0
+          ? 0
+          : 1 + ::_pbi::WireFormatLite::Int32Size(
+                              static_cast<int32_t>(data_size))
+      ;
+      total_size += tag_size + data_size;
+    }
   }
   cached_has_bits = _impl_._has_bits_[0];
   if (cached_has_bits & 0x0000000fu) {
@@ -13518,25 +13521,21 @@ PROTOBUF_NOINLINE void GeneratedCodeInfo_Annotation::Clear() {
       total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
                                       this->_internal_source_file());
     }
-
     // optional int32 begin = 3;
     if (cached_has_bits & 0x00000002u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_begin());
     }
-
     // optional int32 end = 4;
     if (cached_has_bits & 0x00000004u) {
       total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
           this->_internal_end());
     }
-
     // optional .google.protobuf.GeneratedCodeInfo.Annotation.Semantic semantic = 5;
     if (cached_has_bits & 0x00000008u) {
       total_size += 1 +
                     ::_pbi::WireFormatLite::EnumSize(this->_internal_semantic());
     }
-
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -13737,18 +13736,23 @@ PROTOBUF_NOINLINE void GeneratedCodeInfo::Clear() {
 }
 
 ::size_t GeneratedCodeInfo::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.GeneratedCodeInfo)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.GeneratedCodeInfo)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.GeneratedCodeInfo.Annotation annotation = 1;
-  total_size += 1UL * this->_internal_annotation_size();
-  for (const auto& msg : this->_internal_annotation()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.GeneratedCodeInfo.Annotation annotation = 1;
+     {
+      total_size += 1UL * this->_internal_annotation_size();
+      for (const auto& msg : this->_internal_annotation()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
diff --git a/src/google/protobuf/descriptor.proto b/src/google/protobuf/descriptor.proto
index 8e5e21480a..b4a62d3efa 100644
--- a/src/google/protobuf/descriptor.proto
+++ b/src/google/protobuf/descriptor.proto
@@ -1066,11 +1066,24 @@ message FeatureSet {
 
   reserved 999;
 
-  extensions 1000;  // for Protobuf C++
-  extensions 1001;  // for Protobuf Java
-  extensions 1002;  // for Protobuf Go
-
-  extensions 9990;  // for deprecated Java Proto1
+  extensions 1000 to 9994 [
+    declaration = {
+      number: 1000,
+      full_name: ".pb.cpp",
+      type: ".pb.CppFeatures"
+    },
+    declaration = {
+      number: 1001,
+      full_name: ".pb.java",
+      type: ".pb.JavaFeatures"
+    },
+    declaration = { number: 1002, full_name: ".pb.go", type: ".pb.GoFeatures" },
+    declaration = {
+      number: 9990,
+      full_name: ".pb.proto1",
+      type: ".pb.Proto1Features"
+    }
+  ];
 
   extensions 9995 to 9999;  // For internal testing
   extensions 10000;         // for https://github.com/bufbuild/protobuf-es
diff --git a/src/google/protobuf/descriptor_unittest.cc b/src/google/protobuf/descriptor_unittest.cc
index ad37a443bc..0c173c97d3 100644
--- a/src/google/protobuf/descriptor_unittest.cc
+++ b/src/google/protobuf/descriptor_unittest.cc
@@ -4059,6 +4059,22 @@ class ValidationErrorTest : public testing::Test {
     return ABSL_DIE_IF_NULL(pool_.BuildFile(file_proto));
   }
 
+  const FileDescriptor* ParseAndBuildFile(absl::string_view file_name,
+                                          absl::string_view file_text) {
+    io::ArrayInputStream input_stream(file_text.data(), file_text.size());
+    SimpleErrorCollector error_collector;
+    io::Tokenizer tokenizer(&input_stream, &error_collector);
+    compiler::Parser parser;
+    parser.RecordErrorsTo(&error_collector);
+    FileDescriptorProto proto;
+    ABSL_CHECK(parser.Parse(&tokenizer, &proto))
+        << error_collector.last_error() << "\n"
+        << file_text;
+    ABSL_CHECK_EQ("", error_collector.last_error());
+    proto.set_name(file_name);
+    return pool_.BuildFile(proto);
+  }
+
 
   // Add file_proto to the DescriptorPool. Expect errors to be produced which
   // match the given error text.
@@ -8684,7 +8700,9 @@ TEST_F(FeaturesTest, OneofFieldFeaturesOverride) {
 }
 
 TEST_F(FeaturesTest, MapFieldFeaturesOverride) {
-  constexpr absl::string_view kProtoFile = R"schema(
+  BuildDescriptorMessagesInTestPool();
+  BuildFileInTestPool(pb::TestFeatures::descriptor()->file());
+  const FileDescriptor* file = ParseAndBuildFile("foo.proto", R"schema(
     edition = "2023";
 
     import "google/protobuf/unittest_features.proto";
@@ -8701,22 +8719,7 @@ TEST_F(FeaturesTest, MapFieldFeaturesOverride) {
         features.(pb.test).multiple_feature = VALUE3
       ];
     }
-  )schema";
-  io::ArrayInputStream input_stream(kProtoFile.data(), kProtoFile.size());
-  SimpleErrorCollector error_collector;
-  io::Tokenizer tokenizer(&input_stream, &error_collector);
-  compiler::Parser parser;
-  parser.RecordErrorsTo(&error_collector);
-  FileDescriptorProto proto;
-  ASSERT_TRUE(parser.Parse(&tokenizer, &proto))
-      << error_collector.last_error() << "\n"
-      << kProtoFile;
-  ASSERT_EQ("", error_collector.last_error());
-  proto.set_name("foo.proto");
-
-  BuildDescriptorMessagesInTestPool();
-  BuildFileInTestPool(pb::TestFeatures::descriptor()->file());
-  const FileDescriptor* file = pool_.BuildFile(proto);
+  )schema");
   ASSERT_THAT(file, NotNull());
 
   const FieldDescriptor* map_field = file->message_type(0)->field(0);
@@ -8744,7 +8747,8 @@ TEST_F(FeaturesTest, MapFieldFeaturesOverride) {
 }
 
 TEST_F(FeaturesTest, MapFieldFeaturesStringValidation) {
-  constexpr absl::string_view kProtoFile = R"schema(
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = ParseAndBuildFile("foo.proto", R"schema(
     edition = "2023";
 
     message Foo {
@@ -8758,21 +8762,7 @@ TEST_F(FeaturesTest, MapFieldFeaturesStringValidation) {
         features.utf8_validation = NONE
       ];
     }
-  )schema";
-  io::ArrayInputStream input_stream(kProtoFile.data(), kProtoFile.size());
-  SimpleErrorCollector error_collector;
-  io::Tokenizer tokenizer(&input_stream, &error_collector);
-  compiler::Parser parser;
-  parser.RecordErrorsTo(&error_collector);
-  FileDescriptorProto proto;
-  ASSERT_TRUE(parser.Parse(&tokenizer, &proto))
-      << error_collector.last_error() << "\n"
-      << kProtoFile;
-  ASSERT_EQ("", error_collector.last_error());
-  proto.set_name("foo.proto");
-
-  BuildDescriptorMessagesInTestPool();
-  const FileDescriptor* file = pool_.BuildFile(proto);
+  )schema");
   ASSERT_THAT(file, NotNull());
 
   auto validate_map_field = [](const FieldDescriptor* field) {
@@ -8789,6 +8779,109 @@ TEST_F(FeaturesTest, MapFieldFeaturesStringValidation) {
   validate_map_field(file->message_type(0)->field(2));
 }
 
+TEST_F(FeaturesTest, MapFieldFeaturesImplicitPresence) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* editions = ParseAndBuildFile("editions.proto", R"schema(
+    edition = "2023";
+
+    option features.field_presence = IMPLICIT;
+
+    message Foo {
+      map<string, Foo> message_map = 1;
+      map<string, string> string_map = 2;
+    }
+  )schema");
+  ASSERT_THAT(editions, NotNull());
+  const FileDescriptor* proto3 = ParseAndBuildFile("proto3.proto", R"schema(
+    syntax = "proto3";
+
+    message Bar {
+      map<string, Bar> message_map = 1;
+      map<string, string> string_map = 2;
+    }
+  )schema");
+  ASSERT_THAT(proto3, NotNull());
+
+  auto validate_maps = [](const FileDescriptor* file) {
+    const FieldDescriptor* message_map = file->message_type(0)->field(0);
+    EXPECT_FALSE(message_map->has_presence());
+    EXPECT_FALSE(message_map->message_type()->field(0)->has_presence());
+    EXPECT_TRUE(message_map->message_type()->field(1)->has_presence());
+
+    const FieldDescriptor* string_map = file->message_type(0)->field(1);
+    EXPECT_FALSE(string_map->has_presence());
+    EXPECT_FALSE(string_map->message_type()->field(0)->has_presence());
+    EXPECT_FALSE(string_map->message_type()->field(1)->has_presence());
+  };
+  validate_maps(editions);
+  validate_maps(proto3);
+}
+
+TEST_F(FeaturesTest, MapFieldFeaturesExplicitPresence) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* editions = ParseAndBuildFile("editions.proto", R"schema(
+    edition = "2023";
+
+    message Foo {
+      map<string, Foo> message_map = 1;
+      map<string, string> string_map = 2;
+    }
+  )schema");
+  ASSERT_THAT(editions, NotNull());
+  const FileDescriptor* proto2 = ParseAndBuildFile("google.protobuf.proto", R"schema(
+    syntax = "proto2";
+
+    message Bar {
+      map<string, Bar> message_map = 1;
+      map<string, string> string_map = 2;
+    }
+  )schema");
+  ASSERT_THAT(proto2, NotNull());
+
+  auto validate_maps = [](const FileDescriptor* file) {
+    const FieldDescriptor* message_map = file->message_type(0)->field(0);
+    EXPECT_FALSE(message_map->has_presence());
+    EXPECT_TRUE(message_map->message_type()->field(0)->has_presence());
+    EXPECT_TRUE(message_map->message_type()->field(1)->has_presence());
+
+    const FieldDescriptor* string_map = file->message_type(0)->field(1);
+    EXPECT_FALSE(string_map->has_presence());
+    EXPECT_TRUE(string_map->message_type()->field(0)->has_presence());
+    EXPECT_TRUE(string_map->message_type()->field(1)->has_presence());
+  };
+  validate_maps(editions);
+  validate_maps(proto2);
+}
+
+TEST_F(FeaturesTest, MapFieldFeaturesInheritedMessageEncoding) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = ParseAndBuildFile("foo.proto", R"schema(
+    edition = "2023";
+    
+    option features.message_encoding = DELIMITED;
+
+    message Foo {
+      map<int32, Foo> message_map = 1;
+      map<string, string> string_map = 2;
+    }
+  )schema");
+  ASSERT_THAT(file, NotNull());
+
+  const FieldDescriptor* message_map = file->message_type(0)->field(0);
+  EXPECT_EQ(message_map->type(), FieldDescriptor::TYPE_MESSAGE);
+  EXPECT_EQ(message_map->message_type()->field(0)->type(),
+            FieldDescriptor::TYPE_INT32);
+  EXPECT_EQ(message_map->message_type()->field(1)->type(),
+            FieldDescriptor::TYPE_MESSAGE);
+
+  const FieldDescriptor* string_map = file->message_type(0)->field(1);
+  EXPECT_EQ(string_map->type(), FieldDescriptor::TYPE_MESSAGE);
+  EXPECT_EQ(string_map->message_type()->field(0)->type(),
+            FieldDescriptor::TYPE_STRING);
+  EXPECT_EQ(string_map->message_type()->field(1)->type(),
+            FieldDescriptor::TYPE_STRING);
+}
+
 TEST_F(FeaturesTest, RootExtensionFeaturesOverride) {
   BuildDescriptorMessagesInTestPool();
   BuildFileInTestPool(pb::TestFeatures::descriptor()->file());
@@ -9737,7 +9830,62 @@ TEST_F(FeaturesTest, InvalidFieldImplicitDefault) {
       "defaults.\n");
 }
 
-TEST_F(FeaturesTest, InvalidFieldImplicitOpen) {
+TEST_F(FeaturesTest, ValidExtensionFieldImplicitDefault) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = BuildFile(
+      R"pb(
+        name: "foo.proto"
+        syntax: "editions"
+        edition: EDITION_2023
+        options { features { field_presence: IMPLICIT } }
+        message_type {
+          name: "Foo"
+          extension_range { start: 1 end: 100 }
+        }
+        extension {
+          name: "bar"
+          number: 1
+          label: LABEL_OPTIONAL
+          type: TYPE_STRING
+          default_value: "Hello world"
+          extendee: "Foo"
+        }
+      )pb");
+  ASSERT_THAT(file, NotNull());
+
+  EXPECT_TRUE(file->extension(0)->has_presence());
+  EXPECT_EQ(file->extension(0)->default_value_string(), "Hello world");
+}
+
+TEST_F(FeaturesTest, ValidOneofFieldImplicitDefault) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = BuildFile(
+      R"pb(
+        name: "foo.proto"
+        syntax: "editions"
+        edition: EDITION_2023
+        options { features { field_presence: IMPLICIT } }
+        message_type {
+          name: "Foo"
+          field {
+            name: "bar"
+            number: 1
+            label: LABEL_OPTIONAL
+            type: TYPE_STRING
+            default_value: "Hello world"
+            oneof_index: 0
+          }
+          oneof_decl { name: "_foo" }
+        }
+      )pb");
+  ASSERT_THAT(file, NotNull());
+
+  EXPECT_TRUE(file->message_type(0)->field(0)->has_presence());
+  EXPECT_EQ(file->message_type(0)->field(0)->default_value_string(),
+            "Hello world");
+}
+
+TEST_F(FeaturesTest, InvalidFieldImplicitClosed) {
   BuildDescriptorMessagesInTestPool();
   BuildFileWithErrors(
       R"pb(
@@ -9765,6 +9913,68 @@ TEST_F(FeaturesTest, InvalidFieldImplicitOpen) {
       "be open.\n");
 }
 
+TEST_F(FeaturesTest, ValidRepeatedFieldImplicitClosed) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = BuildFile(
+      R"pb(
+        name: "foo.proto"
+        syntax: "editions"
+        edition: EDITION_2023
+        options { features { field_presence: IMPLICIT } }
+        message_type {
+          name: "Foo"
+          field {
+            name: "bar"
+            number: 1
+            label: LABEL_REPEATED
+            type: TYPE_ENUM
+            type_name: "Enum"
+          }
+        }
+        enum_type {
+          name: "Enum"
+          value { name: "BAR" number: 0 }
+          options { features { enum_type: CLOSED } }
+        }
+      )pb");
+  ASSERT_THAT(file, NotNull());
+
+  EXPECT_FALSE(file->message_type(0)->field(0)->has_presence());
+  EXPECT_TRUE(file->enum_type(0)->is_closed());
+}
+
+TEST_F(FeaturesTest, ValidOneofFieldImplicitClosed) {
+  BuildDescriptorMessagesInTestPool();
+  const FileDescriptor* file = BuildFile(
+      R"pb(
+        name: "foo.proto"
+        syntax: "editions"
+        edition: EDITION_2023
+        options { features { field_presence: IMPLICIT } }
+        message_type {
+          name: "Foo"
+          field {
+            name: "bar"
+            number: 1
+            label: LABEL_OPTIONAL
+            type: TYPE_ENUM
+            type_name: "Enum"
+            oneof_index: 0
+          }
+          oneof_decl { name: "_foo" }
+        }
+        enum_type {
+          name: "Enum"
+          value { name: "BAR" number: 0 }
+          options { features { enum_type: CLOSED } }
+        }
+      )pb");
+  ASSERT_THAT(file, NotNull());
+
+  EXPECT_TRUE(file->message_type(0)->field(0)->has_presence());
+  EXPECT_TRUE(file->enum_type(0)->is_closed());
+}
+
 TEST_F(FeaturesTest, InvalidFieldRequiredExtension) {
   BuildDescriptorMessagesInTestPool();
   BuildFileWithErrors(
@@ -13035,7 +13245,7 @@ TEST_F(LazilyBuildDependenciesTest, Type) {
 
   const FileDescriptor* file = pool_.FindFileByName("foo.proto");
 
-  // Verify calling type() on a field that is a message type will
+  // Verify calling type() on a field that is a message type will _not_
   // build the type defined in another file.
   EXPECT_FALSE(pool_.InternalIsFileLoaded("message1.proto"));
   const Descriptor* desc = file->FindMessageTypeByName("Lazy");
@@ -13043,31 +13253,31 @@ TEST_F(LazilyBuildDependenciesTest, Type) {
   const FieldDescriptor* field = desc->FindFieldByName("message1");
   EXPECT_TRUE(field != nullptr);
   EXPECT_EQ(field->type(), FieldDescriptor::TYPE_MESSAGE);
-  EXPECT_TRUE(pool_.InternalIsFileLoaded("message1.proto"));
+  EXPECT_FALSE(pool_.InternalIsFileLoaded("message1.proto"));
 
-  // Verify calling cpp_type() on a field that is a message type will
+  // Verify calling cpp_type() on a field that is a message type will _not_
   // build the type defined in another file.
   EXPECT_FALSE(pool_.InternalIsFileLoaded("message2.proto"));
   field = desc->FindFieldByName("message2");
   EXPECT_TRUE(field != nullptr);
   EXPECT_EQ(field->cpp_type(), FieldDescriptor::CPPTYPE_MESSAGE);
-  EXPECT_TRUE(pool_.InternalIsFileLoaded("message2.proto"));
+  EXPECT_FALSE(pool_.InternalIsFileLoaded("message2.proto"));
 
-  // Verify calling type() on a field that is an enum type will
+  // Verify calling type() on a field that is an enum type will _not_
   // build the type defined in another file.
   EXPECT_FALSE(pool_.InternalIsFileLoaded("enum1.proto"));
   field = desc->FindFieldByName("enum1");
   EXPECT_TRUE(field != nullptr);
   EXPECT_EQ(field->type(), FieldDescriptor::TYPE_ENUM);
-  EXPECT_TRUE(pool_.InternalIsFileLoaded("enum1.proto"));
+  EXPECT_FALSE(pool_.InternalIsFileLoaded("enum1.proto"));
 
-  // Verify calling cpp_type() on a field that is an enum type will
+  // Verify calling cpp_type() on a field that is an enum type will _not_
   // build the type defined in another file.
   EXPECT_FALSE(pool_.InternalIsFileLoaded("enum2.proto"));
   field = desc->FindFieldByName("enum2");
   EXPECT_TRUE(field != nullptr);
   EXPECT_EQ(field->cpp_type(), FieldDescriptor::CPPTYPE_ENUM);
-  EXPECT_TRUE(pool_.InternalIsFileLoaded("enum2.proto"));
+  EXPECT_FALSE(pool_.InternalIsFileLoaded("enum2.proto"));
 }
 
 TEST_F(LazilyBuildDependenciesTest, Extension) {
diff --git a/src/google/protobuf/duration.pb.cc b/src/google/protobuf/duration.pb.cc
index d15b7b08f0..76073738be 100644
--- a/src/google/protobuf/duration.pb.cc
+++ b/src/google/protobuf/duration.pb.cc
@@ -245,26 +245,27 @@ PROTOBUF_NOINLINE void Duration::Clear() {
 }
 
 ::size_t Duration::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Duration)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Duration)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
-
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // int64 seconds = 1;
-  if (this->_internal_seconds() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
-        this->_internal_seconds());
-  }
+  (void)cached_has_bits;
 
-  // int32 nanos = 2;
-  if (this->_internal_nanos() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
-        this->_internal_nanos());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // int64 seconds = 1;
+    if (this->_internal_seconds() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
+          this->_internal_seconds());
+    }
+    // int32 nanos = 2;
+    if (this->_internal_nanos() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+          this->_internal_nanos());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/src/google/protobuf/dynamic_message.cc b/src/google/protobuf/dynamic_message.cc
index 7927107815..c4448d51a0 100644
--- a/src/google/protobuf/dynamic_message.cc
+++ b/src/google/protobuf/dynamic_message.cc
@@ -620,6 +620,7 @@ DynamicMessageFactory::~DynamicMessageFactory() {
 }
 
 const Message* DynamicMessageFactory::GetPrototype(const Descriptor* type) {
+  ABSL_CHECK(type != nullptr);
   absl::MutexLock lock(&prototypes_mutex_);
   return GetPrototypeNoLock(type);
 }
diff --git a/src/google/protobuf/dynamic_message.h b/src/google/protobuf/dynamic_message.h
index 8d53e28cbc..0af9d441b5 100644
--- a/src/google/protobuf/dynamic_message.h
+++ b/src/google/protobuf/dynamic_message.h
@@ -108,8 +108,8 @@ class PROTOBUF_EXPORT DynamicMessageFactory : public MessageFactory {
   // prototype, so these must be destroyed before the DynamicMessageFactory
   // is destroyed.
   //
-  // The given descriptor must outlive the returned message, and hence must
-  // outlive the DynamicMessageFactory.
+  // The given descriptor must be non-null and outlive the returned message, and
+  // hence must outlive the DynamicMessageFactory.
   //
   // The method is thread-safe.
   const Message* GetPrototype(const Descriptor* type) override;
diff --git a/src/google/protobuf/edition_unittest.proto b/src/google/protobuf/edition_unittest.proto
index fadde47d29..81848b87e4 100644
--- a/src/google/protobuf/edition_unittest.proto
+++ b/src/google/protobuf/edition_unittest.proto
@@ -1254,11 +1254,11 @@ message TestNestedGroupExtensionOuter {
     message Layer2RepeatedGroup {
       extensions 3
         // NOTE: extension metadata is not supported due to targets such as
-        // `//third_party/protobuf_legacy_opensource/src:shell_scripts_test`,
+        // `//google/protobuf_legacy_opensource/src:shell_scripts_test`,
         // eee https://screenshot.googleplex.com/Axz2QD8nxjdpyFF
         //[metadata = {
         // NOTE: can't write type there due to some clever build gen code at
-        // http://google3/net/proto2/internal/BUILD;l=1247;rcl=411090862
+        // http://google3/google/protobuf/BUILD;l=1247;rcl=411090862
         // type: "edition_unittest.TestNestedGroupExtensionInnerExtension",
         // name: "inner",
         // }]
diff --git a/src/google/protobuf/endian.h b/src/google/protobuf/endian.h
index 781954e499..6bc90c0dce 100644
--- a/src/google/protobuf/endian.h
+++ b/src/google/protobuf/endian.h
@@ -14,6 +14,8 @@
 
 #include <cstdint>
 
+#include "absl/base/config.h"
+
 // Must be included last.
 #include "google/protobuf/port_def.inc"
 
@@ -22,8 +24,8 @@ namespace protobuf {
 namespace internal {
 
 inline uint64_t BSwap64(uint64_t host_int) {
-#if defined(PROTOBUF_BUILTIN_BSWAP64)
-  return PROTOBUF_BUILTIN_BSWAP64(host_int);
+#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap64)
+  return __builtin_bswap64(host_int);
 #elif defined(_MSC_VER)
   return _byteswap_uint64(host_int);
 #else
@@ -39,8 +41,8 @@ inline uint64_t BSwap64(uint64_t host_int) {
 }
 
 inline uint32_t BSwap32(uint32_t host_int) {
-#if defined(PROTOBUF_BUILTIN_BSWAP32)
-  return PROTOBUF_BUILTIN_BSWAP32(host_int);
+#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap32)
+  return __builtin_bswap32(host_int);
 #elif defined(_MSC_VER)
   return _byteswap_ulong(host_int);
 #else
@@ -52,8 +54,8 @@ inline uint32_t BSwap32(uint32_t host_int) {
 }
 
 inline uint16_t BSwap16(uint16_t host_int) {
-#if defined(PROTOBUF_BUILTIN_BSWAP16)
-  return PROTOBUF_BUILTIN_BSWAP16(host_int);
+#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap16)
+  return __builtin_bswap16(host_int);
 #elif defined(_MSC_VER)
   return _byteswap_ushort(host_int);
 #else
diff --git a/src/google/protobuf/extension_set_heavy.cc b/src/google/protobuf/extension_set_heavy.cc
index 06a6a7f7f7..60ad7b9e83 100644
--- a/src/google/protobuf/extension_set_heavy.cc
+++ b/src/google/protobuf/extension_set_heavy.cc
@@ -406,7 +406,7 @@ size_t ExtensionSet::Extension::SpaceUsedExcludingSelfLong() const {
         if (is_lazy) {
           total_size += lazymessage_value->SpaceUsedLong();
         } else {
-          total_size += DownCast<Message*>(message_value)->SpaceUsedLong();
+          total_size += DownCastToMessage(message_value)->SpaceUsedLong();
         }
         break;
       default:
diff --git a/src/google/protobuf/extension_set_unittest.cc b/src/google/protobuf/extension_set_unittest.cc
index 019eec6da3..f983f3ca49 100644
--- a/src/google/protobuf/extension_set_unittest.cc
+++ b/src/google/protobuf/extension_set_unittest.cc
@@ -26,6 +26,7 @@
 #include "google/protobuf/dynamic_message.h"
 #include "google/protobuf/io/coded_stream.h"
 #include "google/protobuf/io/zero_copy_stream_impl.h"
+#include "google/protobuf/message_lite.h"
 #include "google/protobuf/test_util.h"
 #include "google/protobuf/test_util2.h"
 #include "google/protobuf/text_format.h"
diff --git a/src/google/protobuf/field_mask.pb.cc b/src/google/protobuf/field_mask.pb.cc
index 85e3639111..52e4183374 100644
--- a/src/google/protobuf/field_mask.pb.cc
+++ b/src/google/protobuf/field_mask.pb.cc
@@ -240,19 +240,24 @@ PROTOBUF_NOINLINE void FieldMask::Clear() {
 }
 
 ::size_t FieldMask::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldMask)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FieldMask)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated string paths = 1;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_paths().size());
-  for (int i = 0, n = _internal_paths().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_paths().Get(i));
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated string paths = 1;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_paths().size());
+      for (int i = 0, n = _internal_paths().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_paths().Get(i));
+      }
+    }
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
diff --git a/src/google/protobuf/generated_message_reflection.cc b/src/google/protobuf/generated_message_reflection.cc
index 4d7d748105..92045dabec 100644
--- a/src/google/protobuf/generated_message_reflection.cc
+++ b/src/google/protobuf/generated_message_reflection.cc
@@ -1265,10 +1265,9 @@ void Reflection::InternalSwap(Message* lhs, Message* rhs) const {
     int fields_with_has_bits = 0;
     for (int i = 0; i < descriptor_->field_count(); i++) {
       const FieldDescriptor* field = descriptor_->field(i);
-      if (field->is_repeated() || schema_.InRealOneof(field)) {
-        continue;
+      if (internal::cpp::HasHasbit(field)) {
+        ++fields_with_has_bits;
       }
-      fields_with_has_bits++;
     }
 
     int has_bits_size = (fields_with_has_bits + 31) / 32;
diff --git a/src/google/protobuf/generated_message_reflection_unittest.cc b/src/google/protobuf/generated_message_reflection_unittest.cc
index 94a7c15c35..a432d74d67 100644
--- a/src/google/protobuf/generated_message_reflection_unittest.cc
+++ b/src/google/protobuf/generated_message_reflection_unittest.cc
@@ -41,6 +41,7 @@
 #include "google/protobuf/unittest.pb.h"
 #include "google/protobuf/unittest_mset.pb.h"
 #include "google/protobuf/unittest_mset_wire_format.pb.h"
+#include "google/protobuf/unittest_proto3.pb.h"
 
 // Must be included last.
 #include "google/protobuf/port_def.inc"
@@ -1756,6 +1757,13 @@ TEST(GeneratedMessageReflection, ListFieldsSorted) {
                           Pointee(Property(&FieldDescriptor::number, 101))));
 }
 
+TEST(GeneratedMessageReflection, SwapImplicitPresenceShouldWork) {
+  proto3_unittest::TestHasbits lhs, rhs;
+  rhs.mutable_child()->set_optional_int32(-1);
+  lhs.GetReflection()->Swap(&lhs, &rhs);
+  EXPECT_EQ(lhs.child().optional_int32(), -1);
+}
+
 }  // namespace
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/generated_message_tctable_full.cc b/src/google/protobuf/generated_message_tctable_full.cc
index 75b86d8971..430d375da0 100644
--- a/src/google/protobuf/generated_message_tctable_full.cc
+++ b/src/google/protobuf/generated_message_tctable_full.cc
@@ -44,7 +44,6 @@
 namespace google {
 namespace protobuf {
 namespace internal {
-using ::google::protobuf::internal::DownCast;
 
 const char* TcParser::GenericFallback(PROTOBUF_TC_PARAM_DECL) {
   PROTOBUF_MUSTTAIL return GenericFallbackImpl<Message, UnknownFieldSet>(
@@ -64,7 +63,7 @@ const char* TcParser::ReflectionFallback(PROTOBUF_TC_PARAM_DECL) {
     return ptr;
   }
 
-  auto* full_msg = DownCast<Message*>(msg);
+  auto* full_msg = DownCastToMessage(msg);
   auto* descriptor = full_msg->GetDescriptor();
   auto* reflection = full_msg->GetReflection();
   int field_number = WireFormatLite::GetTagFieldNumber(tag);
@@ -88,7 +87,7 @@ const char* TcParser::ReflectionParseLoop(PROTOBUF_TC_PARAM_DECL) {
   (void)table;
   (void)hasbits;
   // Call into the wire format reflective parse loop.
-  return WireFormat::_InternalParse(DownCast<Message*>(msg), ptr, ctx);
+  return WireFormat::_InternalParse(DownCastToMessage(msg), ptr, ctx);
 }
 
 const char* TcParser::MessageSetWireFormatParseLoop(
diff --git a/src/google/protobuf/generated_message_tctable_gen.h b/src/google/protobuf/generated_message_tctable_gen.h
index 7dbcd8e1b3..a42de2b479 100644
--- a/src/google/protobuf/generated_message_tctable_gen.h
+++ b/src/google/protobuf/generated_message_tctable_gen.h
@@ -96,7 +96,7 @@ struct PROTOBUF_EXPORT TailCallTableInfo {
     uint16_t type_card;
 
     // For internal caching.
-    cpp::Utf8CheckMode utf8_check_mode : 8;
+    cpp::Utf8CheckMode utf8_check_mode;
   };
   std::vector<FieldEntryInfo> field_entries;
 
diff --git a/src/google/protobuf/generated_message_tctable_impl.h b/src/google/protobuf/generated_message_tctable_impl.h
index 4cd6e9582b..1a214be1bb 100644
--- a/src/google/protobuf/generated_message_tctable_impl.h
+++ b/src/google/protobuf/generated_message_tctable_impl.h
@@ -1002,7 +1002,7 @@ inline PROTOBUF_ALWAYS_INLINE const char* TcParser::ParseLoop(
   while (!ctx->Done(&ptr)) {
 #if defined(__GNUC__)
     // Note: this asm prevents the compiler (clang, specifically) from
-    // believing (thanks to CSE) that it needs to dedicate a registeer both
+    // believing (thanks to CSE) that it needs to dedicate a register both
     // to "table" and "&table->fast_entries".
     // TODO: remove this asm
     asm("" : "+r"(table));
diff --git a/src/google/protobuf/lite_unittest.cc b/src/google/protobuf/lite_unittest.cc
index 978307528a..f9f0135501 100644
--- a/src/google/protobuf/lite_unittest.cc
+++ b/src/google/protobuf/lite_unittest.cc
@@ -27,6 +27,7 @@
 #include "google/protobuf/io/zero_copy_stream_impl_lite.h"
 #include "google/protobuf/map_lite_test_util.h"
 #include "google/protobuf/map_lite_unittest.pb.h"
+#include "google/protobuf/message_lite.h"
 #include "google/protobuf/parse_context.h"
 #include "google/protobuf/test_util_lite.h"
 #include "google/protobuf/unittest_lite.pb.h"
@@ -1325,6 +1326,92 @@ TEST(LiteBasicTest, CodedInputStreamRollback) {
   }
 }
 
+// Two arbitary types
+using CastType1 = protobuf_unittest::TestAllTypesLite;
+using CastType2 = protobuf_unittest::TestPackedTypesLite;
+
+TEST(LiteTest, DynamicCastToGenerated) {
+  CastType1 test_type_1;
+
+  MessageLite* test_type_1_pointer = &test_type_1;
+  EXPECT_EQ(&test_type_1,
+            DynamicCastToGenerated<CastType1>(test_type_1_pointer));
+  EXPECT_EQ(nullptr, DynamicCastToGenerated<CastType2>(test_type_1_pointer));
+
+  const MessageLite* test_type_1_pointer_const = &test_type_1;
+  EXPECT_EQ(&test_type_1,
+            DynamicCastToGenerated<const CastType1>(test_type_1_pointer_const));
+  EXPECT_EQ(nullptr,
+            DynamicCastToGenerated<const CastType2>(test_type_1_pointer_const));
+
+  MessageLite* test_type_1_pointer_nullptr = nullptr;
+  EXPECT_EQ(nullptr,
+            DynamicCastToGenerated<CastType1>(test_type_1_pointer_nullptr));
+
+  MessageLite& test_type_1_pointer_ref = test_type_1;
+  EXPECT_EQ(&test_type_1,
+            &DynamicCastToGenerated<CastType1>(test_type_1_pointer_ref));
+
+  const MessageLite& test_type_1_pointer_const_ref = test_type_1;
+  EXPECT_EQ(&test_type_1,
+            &DynamicCastToGenerated<CastType1>(test_type_1_pointer_const_ref));
+}
+
+#if GTEST_HAS_DEATH_TEST
+TEST(LiteTest, DynamicCastToGeneratedInvalidReferenceType) {
+  CastType1 test_type_1;
+  const MessageLite& test_type_1_pointer_const_ref = test_type_1;
+  ASSERT_DEATH(DynamicCastToGenerated<CastType2>(test_type_1_pointer_const_ref),
+               "Cannot downcast " + test_type_1.GetTypeName() + " to " +
+                   CastType2::default_instance().GetTypeName());
+}
+#endif  // GTEST_HAS_DEATH_TEST
+
+TEST(LiteTest, DownCastToGeneratedValidType) {
+  CastType1 test_type_1;
+
+  MessageLite* test_type_1_pointer = &test_type_1;
+  EXPECT_EQ(&test_type_1, DownCastToGenerated<CastType1>(test_type_1_pointer));
+
+  const MessageLite* test_type_1_pointer_const = &test_type_1;
+  EXPECT_EQ(&test_type_1,
+            DownCastToGenerated<const CastType1>(test_type_1_pointer_const));
+
+  MessageLite* test_type_1_pointer_nullptr = nullptr;
+  EXPECT_EQ(nullptr,
+            DownCastToGenerated<CastType1>(test_type_1_pointer_nullptr));
+
+  MessageLite& test_type_1_pointer_ref = test_type_1;
+  EXPECT_EQ(&test_type_1,
+            &DownCastToGenerated<CastType1>(test_type_1_pointer_ref));
+
+  const MessageLite& test_type_1_pointer_const_ref = test_type_1;
+  EXPECT_EQ(&test_type_1,
+            &DownCastToGenerated<CastType1>(test_type_1_pointer_const_ref));
+}
+
+#if GTEST_HAS_DEATH_TEST
+TEST(LiteTest, DownCastToGeneratedInvalidPointerType) {
+  CastType1 test_type_1;
+
+  MessageLite* test_type_1_pointer = &test_type_1;
+
+  ASSERT_DEBUG_DEATH(DownCastToGenerated<CastType2>(test_type_1_pointer),
+                     "Cannot downcast " + test_type_1.GetTypeName() + " to " +
+                         CastType2::default_instance().GetTypeName());
+}
+
+TEST(LiteTest, DownCastToGeneratedInvalidReferenceType) {
+  CastType1 test_type_1;
+
+  MessageLite& test_type_1_pointer = test_type_1;
+
+  ASSERT_DEBUG_DEATH(DownCastToGenerated<CastType2>(test_type_1_pointer),
+                     "Cannot downcast " + test_type_1.GetTypeName() + " to " +
+                         CastType2::default_instance().GetTypeName());
+}
+#endif  // GTEST_HAS_DEATH_TEST
+
 }  // namespace
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/map_field.cc b/src/google/protobuf/map_field.cc
index 6496d715f8..3045730932 100644
--- a/src/google/protobuf/map_field.cc
+++ b/src/google/protobuf/map_field.cc
@@ -21,7 +21,6 @@
 namespace google {
 namespace protobuf {
 namespace internal {
-using ::google::protobuf::internal::DownCast;
 
 VariantKey RealKeyToVariantKey<MapKey>::operator()(const MapKey& value) const {
   switch (value.type()) {
diff --git a/src/google/protobuf/map_test.inc b/src/google/protobuf/map_test.inc
index cb396b79e0..c67cd586c3 100644
--- a/src/google/protobuf/map_test.inc
+++ b/src/google/protobuf/map_test.inc
@@ -1578,7 +1578,7 @@ TEST_F(MapFieldReflectionTest, RegularFields) {
           message_int32_message.GetReflection()->GetInt32(
               message_int32_message, fd_map_int32_foreign_message_key);
       const ForeignMessage& value_int32_message =
-          DownCast<const ForeignMessage&>(
+          DownCastToGenerated<ForeignMessage>(
               message_int32_message.GetReflection()->GetMessage(
                   message_int32_message, fd_map_int32_foreign_message_value));
       EXPECT_EQ(value_int32_message.c(), Func(key_int32_message, 6));
@@ -1615,7 +1615,7 @@ TEST_F(MapFieldReflectionTest, RegularFields) {
           message_int32_message.GetReflection()->GetInt32(
               message_int32_message, fd_map_int32_foreign_message_key);
       const ForeignMessage& value_int32_message =
-          DownCast<const ForeignMessage&>(
+          DownCastToGenerated<ForeignMessage>(
               message_int32_message.GetReflection()->GetMessage(
                   message_int32_message, fd_map_int32_foreign_message_value));
       EXPECT_EQ(value_int32_message.c(), Func(key_int32_message, 6));
@@ -1652,7 +1652,7 @@ TEST_F(MapFieldReflectionTest, RegularFields) {
       int32_t key_int32_message =
           message_int32_message->GetReflection()->GetInt32(
               *message_int32_message, fd_map_int32_foreign_message_key);
-      ForeignMessage* value_int32_message = DownCast<ForeignMessage*>(
+      ForeignMessage* value_int32_message = DownCastToGenerated<ForeignMessage>(
           message_int32_message->GetReflection()->MutableMessage(
               message_int32_message, fd_map_int32_foreign_message_value));
       value_int32_message->set_c(Func(key_int32_message, -6));
@@ -1808,7 +1808,7 @@ TEST_F(MapFieldReflectionTest, RepeatedFieldRefForRegularFields) {
           message_int32_message.GetReflection()->GetInt32(
               message_int32_message, fd_map_int32_foreign_message_key);
       const ForeignMessage& value_int32_message =
-          DownCast<const ForeignMessage&>(
+          DownCastToGenerated<ForeignMessage>(
               message_int32_message.GetReflection()->GetMessage(
                   message_int32_message, fd_map_int32_foreign_message_value));
       EXPECT_EQ(value_int32_message.c(), Func(key_int32_message, 6));
@@ -1849,7 +1849,7 @@ TEST_F(MapFieldReflectionTest, RepeatedFieldRefForRegularFields) {
           message_int32_message.GetReflection()->GetInt32(
               message_int32_message, fd_map_int32_foreign_message_key);
       const ForeignMessage& value_int32_message =
-          DownCast<const ForeignMessage&>(
+          DownCastToGenerated<ForeignMessage>(
               message_int32_message.GetReflection()->GetMessage(
                   message_int32_message, fd_map_int32_foreign_message_value));
       EXPECT_EQ(value_int32_message.c(), Func(key_int32_message, 6));
@@ -1966,8 +1966,8 @@ TEST_F(MapFieldReflectionTest, RepeatedFieldRefForRegularFields) {
       const Message& message = *it;
       int32_t key = message.GetReflection()->GetInt32(
           message, fd_map_int32_foreign_message_key);
-      const ForeignMessage& sub_message =
-          DownCast<const ForeignMessage&>(message.GetReflection()->GetMessage(
+      const ForeignMessage& sub_message = DownCastToGenerated<ForeignMessage>(
+          message.GetReflection()->GetMessage(
               message, fd_map_int32_foreign_message_value));
       result[key].MergeFrom(sub_message);
       ++index;
@@ -2120,14 +2120,14 @@ TEST_F(MapFieldReflectionTest, RepeatedFieldRefForRegularFields) {
   {
     const Message& message0a =
         mmf_int32_foreign_message.Get(0, entry_int32_foreign_message.get());
-    const ForeignMessage& sub_message0a =
-        DownCast<const ForeignMessage&>(message0a.GetReflection()->GetMessage(
+    const ForeignMessage& sub_message0a = DownCastToGenerated<ForeignMessage>(
+        message0a.GetReflection()->GetMessage(
             message0a, fd_map_int32_foreign_message_value));
     int32_t int32_value0a = sub_message0a.c();
     const Message& message9a =
         mmf_int32_foreign_message.Get(9, entry_int32_foreign_message.get());
-    const ForeignMessage& sub_message9a =
-        DownCast<const ForeignMessage&>(message9a.GetReflection()->GetMessage(
+    const ForeignMessage& sub_message9a = DownCastToGenerated<ForeignMessage>(
+        message9a.GetReflection()->GetMessage(
             message9a, fd_map_int32_foreign_message_value));
     int32_t int32_value9a = sub_message9a.c();
 
@@ -2135,14 +2135,14 @@ TEST_F(MapFieldReflectionTest, RepeatedFieldRefForRegularFields) {
 
     const Message& message0b =
         mmf_int32_foreign_message.Get(0, entry_int32_foreign_message.get());
-    const ForeignMessage& sub_message0b =
-        DownCast<const ForeignMessage&>(message0b.GetReflection()->GetMessage(
+    const ForeignMessage& sub_message0b = DownCastToGenerated<ForeignMessage>(
+        message0b.GetReflection()->GetMessage(
             message0b, fd_map_int32_foreign_message_value));
     int32_t int32_value0b = sub_message0b.c();
     const Message& message9b =
         mmf_int32_foreign_message.Get(9, entry_int32_foreign_message.get());
-    const ForeignMessage& sub_message9b =
-        DownCast<const ForeignMessage&>(message9b.GetReflection()->GetMessage(
+    const ForeignMessage& sub_message9b = DownCastToGenerated<ForeignMessage>(
+        message9b.GetReflection()->GetMessage(
             message9b, fd_map_int32_foreign_message_value));
     int32_t int32_value9b = sub_message9b.c();
 
diff --git a/src/google/protobuf/message.cc b/src/google/protobuf/message.cc
index caf941ad5b..2f4f84e4fd 100644
--- a/src/google/protobuf/message.cc
+++ b/src/google/protobuf/message.cc
@@ -63,12 +63,11 @@ void RegisterFileLevelMetadata(const DescriptorTable* descriptor_table);
 
 }  // namespace internal
 
-using internal::DownCast;
 using internal::ReflectionOps;
 using internal::WireFormat;
 
 void Message::MergeImpl(MessageLite& to, const MessageLite& from) {
-  ReflectionOps::Merge(DownCast<const Message&>(from), DownCast<Message*>(&to));
+  ReflectionOps::Merge(DownCastToMessage(from), DownCastToMessage(&to));
 }
 
 void Message::MergeFrom(const Message& from) {
@@ -82,7 +81,7 @@ void Message::MergeFrom(const Message& from) {
 }
 
 void Message::CheckTypeAndMergeFrom(const MessageLite& other) {
-  MergeFrom(*DownCast<const Message*>(&other));
+  MergeFrom(DownCastToMessage(other));
 }
 
 void Message::CopyFrom(const Message& from) {
@@ -113,7 +112,7 @@ void Message::CopyFrom(const Message& from) {
 void Message::Clear() { ReflectionOps::Clear(this); }
 
 bool Message::IsInitializedImpl(const MessageLite& msg) {
-  return ReflectionOps::IsInitialized(DownCast<const Message&>(msg));
+  return ReflectionOps::IsInitialized(DownCastToMessage(msg));
 }
 
 void Message::FindInitializationErrors(std::vector<std::string>* errors) const {
@@ -189,20 +188,20 @@ size_t Message::SpaceUsedLong() const {
 }
 
 static std::string GetTypeNameImpl(const MessageLite& msg) {
-  return DownCast<const Message&>(msg).GetDescriptor()->full_name();
+  return DownCastToMessage(msg).GetDescriptor()->full_name();
 }
 
 static std::string InitializationErrorStringImpl(const MessageLite& msg) {
-  return DownCast<const Message&>(msg).InitializationErrorString();
+  return DownCastToMessage(msg).InitializationErrorString();
 }
 
 const internal::TcParseTableBase* Message::GetTcParseTableImpl(
     const MessageLite& msg) {
-  return DownCast<const Message&>(msg).GetReflection()->GetTcParseTable();
+  return DownCastToMessage(msg).GetReflection()->GetTcParseTable();
 }
 
 size_t Message::SpaceUsedLongImpl(const MessageLite& msg_lite) {
-  auto& msg = DownCast<const Message&>(msg_lite);
+  auto& msg = DownCastToMessage(msg_lite);
   return msg.GetReflection()->SpaceUsedLong(msg);
 }
 
diff --git a/src/google/protobuf/message.h b/src/google/protobuf/message.h
index 0354c9e9d7..38249d1e51 100644
--- a/src/google/protobuf/message.h
+++ b/src/google/protobuf/message.h
@@ -1424,90 +1424,6 @@ DECLARE_GET_REPEATED_FIELD(bool)
 
 #undef DECLARE_GET_REPEATED_FIELD
 
-// Tries to downcast this message to a generated message type.  Returns nullptr
-// if this class is not an instance of T.  This works even if RTTI is disabled.
-//
-// This also has the effect of creating a strong reference to T that will
-// prevent the linker from stripping it out at link time.  This can be important
-// if you are using a DynamicMessageFactory that delegates to the generated
-// factory.
-template <typename T>
-const T* DynamicCastToGenerated(const Message* from) {
-  // Compile-time assert that T is a generated type that has a
-  // default_instance() accessor, but avoid actually calling it.
-  const T& (*get_default_instance)() = &T::default_instance;
-  (void)get_default_instance;
-
-  // Compile-time assert that T is a subclass of google::protobuf::Message.
-  const Message* unused = static_cast<T*>(nullptr);
-  (void)unused;
-
-#if PROTOBUF_RTTI
-  internal::StrongReferenceToType<T>();
-  return dynamic_cast<const T*>(from);
-#else
-  bool ok = from != nullptr &&
-            T::default_instance().GetReflection() == from->GetReflection();
-  return ok ? internal::DownCast<const T*>(from) : nullptr;
-#endif
-}
-
-template <typename T>
-T* DynamicCastToGenerated(Message* from) {
-  const Message* message_const = from;
-  return const_cast<T*>(DynamicCastToGenerated<T>(message_const));
-}
-
-// An overloaded version of DynamicCastToGenerated for downcasting references to
-// base Message class. If the destination type T if the argument is not an
-// instance of T and dynamic_cast returns nullptr, it terminates with an error.
-template <typename T>
-const T& DynamicCastToGenerated(const Message& from) {
-  const T* destination_message = DynamicCastToGenerated<T>(&from);
-  ABSL_CHECK(destination_message != nullptr)
-      << "Cannot downcast " << from.GetTypeName() << " to "
-      << T::default_instance().GetTypeName();
-  return *destination_message;
-}
-
-template <typename T>
-T& DynamicCastToGenerated(Message& from) {
-  const Message& message_const = from;
-  const T& destination_message = DynamicCastToGenerated<T>(message_const);
-  return const_cast<T&>(destination_message);
-}
-
-// A lightweight function for downcasting base Message pointer to derived type.
-// It should only be used when the caller is certain that the argument is of
-// instance T and T is a type derived from base Message class.
-template <typename T>
-const T* DownCastToGenerated(const Message* from) {
-  internal::StrongReferenceToType<T>();
-  ABSL_DCHECK(DynamicCastToGenerated<T>(from) == from)
-      << "Cannot downcast " << from->GetTypeName() << " to "
-      << T::default_instance().GetTypeName();
-
-  return static_cast<const T*>(from);
-}
-
-template <typename T>
-T* DownCastToGenerated(Message* from) {
-  const Message* message_const = from;
-  return const_cast<T*>(DownCastToGenerated<T>(message_const));
-}
-
-template <typename T>
-const T& DownCastToGenerated(const Message& from) {
-  return *DownCastToGenerated<T>(&from);
-}
-
-template <typename T>
-T& DownCastToGenerated(Message& from) {
-  const Message& message_const = from;
-  const T& destination_message = DownCastToGenerated<T>(message_const);
-  return const_cast<T&>(destination_message);
-}
-
 // Call this function to ensure that this message's reflection is linked into
 // the binary:
 //
@@ -1533,6 +1449,47 @@ void LinkMessageReflection() {
   internal::StrongReferenceToType<T>();
 }
 
+// Tries to downcast this message from MessageLite to Message.  Returns nullptr
+// if this class is not an instance of Message. eg if the message was defined
+// with optimized_for=LITE_RUNTIME. This works even if RTTI is disabled.
+inline const Message* DynamicCastToMessage(const MessageLite* lite) {
+  return lite == nullptr || internal::GetClassData(*lite)->is_lite
+             ? nullptr
+             : static_cast<const Message*>(lite);
+}
+inline Message* DynamicCastToMessage(MessageLite* lite) {
+  return const_cast<Message*>(
+      DynamicCastToMessage(static_cast<const MessageLite*>(lite)));
+}
+inline const Message& DynamicCastToMessage(const MessageLite& lite) {
+  auto* res = DynamicCastToMessage(&lite);
+  ABSL_CHECK(res != nullptr)
+      << "Cannot to `Message` type " << lite.GetTypeName();
+  return *res;
+}
+inline Message& DynamicCastToMessage(MessageLite& lite) {
+  return const_cast<Message&>(
+      DynamicCastToMessage(static_cast<const MessageLite&>(lite)));
+}
+
+// A lightweight function for downcasting a MessageLite to Message. It should
+// only be used when the caller is certain that the argument is a Message
+// object.
+inline const Message* DownCastToMessage(const MessageLite* lite) {
+  ABSL_CHECK(lite == nullptr || DynamicCastToMessage(lite) != nullptr);
+  return static_cast<const Message*>(lite);
+}
+inline Message* DownCastToMessage(MessageLite* lite) {
+  return const_cast<Message*>(
+      DownCastToMessage(static_cast<const MessageLite*>(lite)));
+}
+inline const Message& DownCastToMessage(const MessageLite& lite) {
+  return *DownCastToMessage(&lite);
+}
+inline Message& DownCastToMessage(MessageLite& lite) {
+  return *DownCastToMessage(&lite);
+}
+
 // =============================================================================
 // Implementation details for {Get,Mutable}RawRepeatedPtrField.  We provide
 // specializations for <std::string>, <StringPieceField> and <Message> and
diff --git a/src/google/protobuf/message_lite.h b/src/google/protobuf/message_lite.h
index 1b85aa0c65..a625c20059 100644
--- a/src/google/protobuf/message_lite.h
+++ b/src/google/protobuf/message_lite.h
@@ -21,6 +21,7 @@
 #include <cstdint>
 #include <iosfwd>
 #include <string>
+#include <type_traits>
 
 #include "absl/base/attributes.h"
 #include "absl/log/absl_check.h"
@@ -53,6 +54,7 @@ class FastReflectionStringSetter;
 class Reflection;
 class Descriptor;
 class AssignDescriptorsHelper;
+class MessageLite;
 
 namespace io {
 
@@ -120,6 +122,10 @@ class PROTOBUF_EXPORT CachedSize {
 #endif
 };
 
+// For MessageLite to friend.
+class TypeId;
+auto GetClassData(const MessageLite& msg);
+
 class SwapFieldHelper;
 
 // See parse_context.h for explanation
@@ -638,6 +644,15 @@ class PROTOBUF_EXPORT MessageLite {
   // return a default table instead of a unique one.
   virtual const ClassData* GetClassData() const = 0;
 
+  template <typename T>
+  static auto GetClassDataGenerated() {
+    // We could speed this up if needed by avoiding the function call.
+    // In LTO this is likely inlined, so it might not matter.
+    static_assert(
+        std::is_same<const T&, decltype(T::default_instance())>::value, "");
+    return T::default_instance().T::GetClassData();
+  }
+
   internal::InternalMetadata _internal_metadata_;
 
   // Return the cached size object as described by
@@ -682,6 +697,7 @@ class PROTOBUF_EXPORT MessageLite {
   friend class internal::LazyField;
   friend class internal::SwapFieldHelper;
   friend class internal::TcParser;
+  friend class internal::TypeId;
   friend class internal::WeakFieldMap;
   friend class internal::WireFormatLite;
 
@@ -690,6 +706,8 @@ class PROTOBUF_EXPORT MessageLite {
   template <typename Type>
   friend class internal::GenericTypeHandler;
 
+  friend auto internal::GetClassData(const MessageLite& msg);
+
   void LogInitializationErrorMessage() const;
 
   bool MergeFromImpl(io::CodedInputStream* input, ParseFlags parse_flags);
@@ -717,6 +735,34 @@ class PROTOBUF_EXPORT MessageLite {
 
 namespace internal {
 
+// A typeinfo equivalent for protobuf message types. Used for
+// DynamicCastToGenerated.
+// We might make this class public later on to have an alternative to
+// `std::type_info` that works when RTTI is disabled.
+class TypeId {
+ public:
+  constexpr explicit TypeId(const MessageLite::ClassData* data) : data_(data) {}
+
+  friend constexpr bool operator==(TypeId a, TypeId b) {
+    return a.data_ == b.data_;
+  }
+  friend constexpr bool operator!=(TypeId a, TypeId b) { return !(a == b); }
+
+  static TypeId Get(const MessageLite& msg) {
+    return TypeId(msg.GetClassData());
+  }
+
+  template <typename T>
+  static TypeId Get() {
+    return TypeId(MessageLite::GetClassDataGenerated<T>());
+  }
+
+ private:
+  const MessageLite::ClassData* data_;
+};
+
+inline auto GetClassData(const MessageLite& msg) { return msg.GetClassData(); }
+
 template <bool alias>
 bool MergeFromImpl(absl::string_view input, MessageLite* msg,
                    const internal::TcParseTableBase* tc_table,
@@ -820,6 +866,83 @@ T* OnShutdownDelete(T* p) {
 std::string ShortFormat(const MessageLite& message_lite);
 std::string Utf8Format(const MessageLite& message_lite);
 
+// Tries to downcast this message to a generated message type.  Returns nullptr
+// if this class is not an instance of T.  This works even if RTTI is disabled.
+//
+// This also has the effect of creating a strong reference to T that will
+// prevent the linker from stripping it out at link time.  This can be important
+// if you are using a DynamicMessageFactory that delegates to the generated
+// factory.
+template <typename T>
+const T* DynamicCastToGenerated(const MessageLite* from) {
+  static_assert(std::is_base_of<MessageLite, T>::value, "");
+
+  internal::StrongReferenceToType<T>();
+  // We might avoid the call to T::GetClassData() altogether if T were to
+  // expose the class data pointer.
+  if (from == nullptr ||
+      internal::TypeId::Get<T>() != internal::TypeId::Get(*from)) {
+    return nullptr;
+  }
+
+  return static_cast<const T*>(from);
+}
+
+template <typename T>
+const T* DynamicCastToGenerated(const MessageLite* from);
+
+template <typename T>
+T* DynamicCastToGenerated(MessageLite* from) {
+  return const_cast<T*>(
+      DynamicCastToGenerated<T>(static_cast<const MessageLite*>(from)));
+}
+
+// An overloaded version of DynamicCastToGenerated for downcasting references to
+// base Message class. If the argument is not an instance of T, it terminates
+// with an error.
+template <typename T>
+const T& DynamicCastToGenerated(const MessageLite& from) {
+  const T* destination_message = DynamicCastToGenerated<T>(&from);
+  ABSL_CHECK(destination_message != nullptr)
+      << "Cannot downcast " << from.GetTypeName() << " to "
+      << T::default_instance().GetTypeName();
+  return *destination_message;
+}
+
+template <typename T>
+T& DynamicCastToGenerated(MessageLite& from) {
+  return const_cast<T&>(
+      DynamicCastToGenerated<T>(static_cast<const MessageLite&>(from)));
+}
+
+// A lightweight function for downcasting base MessageLite pointer to derived
+// type. It should only be used when the caller is certain that the argument is
+// of instance T and T is a generated message type.
+template <typename T>
+const T* DownCastToGenerated(const MessageLite* from) {
+  internal::StrongReferenceToType<T>();
+  ABSL_DCHECK(DynamicCastToGenerated<T>(from) == from)
+      << "Cannot downcast " << from->GetTypeName() << " to "
+      << T::default_instance().GetTypeName();
+  return static_cast<const T*>(from);
+}
+
+template <typename T>
+T* DownCastToGenerated(MessageLite* from) {
+  return const_cast<T*>(
+      DownCastToGenerated<T>(static_cast<const MessageLite*>(from)));
+}
+
+template <typename T>
+const T& DownCastToGenerated(const MessageLite& from) {
+  return *DownCastToGenerated<T>(&from);
+}
+
+template <typename T>
+T& DownCastToGenerated(MessageLite& from) {
+  return *DownCastToGenerated<T>(&from);
+}
+
 }  // namespace protobuf
 }  // namespace google
 
diff --git a/src/google/protobuf/message_unittest.inc b/src/google/protobuf/message_unittest.inc
index 08b00a482f..2f647fbf4a 100644
--- a/src/google/protobuf/message_unittest.inc
+++ b/src/google/protobuf/message_unittest.inc
@@ -753,35 +753,35 @@ TEST(MESSAGE_TEST_NAME, InitializationErrorString) {
 TEST(MESSAGE_TEST_NAME, DynamicCastToGenerated) {
   UNITTEST::TestAllTypes test_all_types;
 
-  Message* test_all_types_pointer = &test_all_types;
+  MessageLite* test_all_types_pointer = &test_all_types;
   EXPECT_EQ(&test_all_types, DynamicCastToGenerated<UNITTEST::TestAllTypes>(
                                  test_all_types_pointer));
   EXPECT_EQ(nullptr, DynamicCastToGenerated<UNITTEST::TestRequired>(
                          test_all_types_pointer));
 
-  const Message* test_all_types_pointer_const = &test_all_types;
+  const MessageLite* test_all_types_pointer_const = &test_all_types;
   EXPECT_EQ(&test_all_types,
             DynamicCastToGenerated<const UNITTEST::TestAllTypes>(
                 test_all_types_pointer_const));
   EXPECT_EQ(nullptr, DynamicCastToGenerated<const UNITTEST::TestRequired>(
                          test_all_types_pointer_const));
 
-  Message* test_all_types_pointer_nullptr = nullptr;
+  MessageLite* test_all_types_pointer_nullptr = nullptr;
   EXPECT_EQ(nullptr, DynamicCastToGenerated<UNITTEST::TestAllTypes>(
                          test_all_types_pointer_nullptr));
 
-  Message& test_all_types_pointer_ref = test_all_types;
+  MessageLite& test_all_types_pointer_ref = test_all_types;
   EXPECT_EQ(&test_all_types, &DynamicCastToGenerated<UNITTEST::TestAllTypes>(
                                  test_all_types_pointer_ref));
 
-  const Message& test_all_types_pointer_const_ref = test_all_types;
+  const MessageLite& test_all_types_pointer_const_ref = test_all_types;
   EXPECT_EQ(&test_all_types, &DynamicCastToGenerated<UNITTEST::TestAllTypes>(
                                  test_all_types_pointer_const_ref));
 }
 
 TEST(MESSAGE_TEST_NAME, DynamicCastToGeneratedInvalidReferenceType) {
   UNITTEST::TestAllTypes test_all_types;
-  const Message& test_all_types_pointer_const_ref = test_all_types;
+  const MessageLite& test_all_types_pointer_const_ref = test_all_types;
   ASSERT_DEATH(DynamicCastToGenerated<UNITTEST::TestRequired>(
                    test_all_types_pointer_const_ref),
                "Cannot downcast " + test_all_types.GetTypeName() + " to " +
@@ -791,23 +791,23 @@ TEST(MESSAGE_TEST_NAME, DynamicCastToGeneratedInvalidReferenceType) {
 TEST(MESSAGE_TEST_NAME, DownCastToGeneratedValidType) {
   UNITTEST::TestAllTypes test_all_types;
 
-  Message* test_all_types_pointer = &test_all_types;
+  MessageLite* test_all_types_pointer = &test_all_types;
   EXPECT_EQ(&test_all_types, DownCastToGenerated<UNITTEST::TestAllTypes>(
                                  test_all_types_pointer));
 
-  const Message* test_all_types_pointer_const = &test_all_types;
+  const MessageLite* test_all_types_pointer_const = &test_all_types;
   EXPECT_EQ(&test_all_types, DownCastToGenerated<const UNITTEST::TestAllTypes>(
                                  test_all_types_pointer_const));
 
-  Message* test_all_types_pointer_nullptr = nullptr;
+  MessageLite* test_all_types_pointer_nullptr = nullptr;
   EXPECT_EQ(nullptr, DownCastToGenerated<UNITTEST::TestAllTypes>(
                          test_all_types_pointer_nullptr));
 
-  Message& test_all_types_pointer_ref = test_all_types;
+  MessageLite& test_all_types_pointer_ref = test_all_types;
   EXPECT_EQ(&test_all_types, &DownCastToGenerated<UNITTEST::TestAllTypes>(
                                  test_all_types_pointer_ref));
 
-  const Message& test_all_types_pointer_const_ref = test_all_types;
+  const MessageLite& test_all_types_pointer_const_ref = test_all_types;
   EXPECT_EQ(&test_all_types, &DownCastToGenerated<UNITTEST::TestAllTypes>(
                                  test_all_types_pointer_const_ref));
 }
@@ -815,7 +815,7 @@ TEST(MESSAGE_TEST_NAME, DownCastToGeneratedValidType) {
 TEST(MESSAGE_TEST_NAME, DownCastToGeneratedInvalidPointerType) {
   UNITTEST::TestAllTypes test_all_types;
 
-  Message* test_all_types_pointer = &test_all_types;
+  MessageLite* test_all_types_pointer = &test_all_types;
 
   ASSERT_DEBUG_DEATH(
       DownCastToGenerated<UNITTEST::TestRequired>(test_all_types_pointer),
@@ -826,7 +826,7 @@ TEST(MESSAGE_TEST_NAME, DownCastToGeneratedInvalidPointerType) {
 TEST(MESSAGE_TEST_NAME, DownCastToGeneratedInvalidReferenceType) {
   UNITTEST::TestAllTypes test_all_types;
 
-  Message& test_all_types_pointer = test_all_types;
+  MessageLite& test_all_types_pointer = test_all_types;
 
   ASSERT_DEBUG_DEATH(
       DownCastToGenerated<UNITTEST::TestRequired>(test_all_types_pointer),
diff --git a/src/google/protobuf/port.h b/src/google/protobuf/port.h
index 4fec7dc138..a31722cd4d 100644
--- a/src/google/protobuf/port.h
+++ b/src/google/protobuf/port.h
@@ -159,28 +159,34 @@ struct ArenaInitialized {
 };
 
 template <typename To, typename From>
-inline To DownCast(From* f) {
-  static_assert(
-      std::is_base_of<From, typename std::remove_pointer<To>::type>::value,
-      "illegal DownCast");
+void AssertDownCast(From* from) {
+  static_assert(std::is_base_of<From, To>::value, "illegal DownCast");
+
+#if defined(__cpp_concepts)
+  // Check that this function is not used to downcast message types.
+  // For those we should use {Down,Dynamic}CastTo{Message,Generated}.
+  static_assert(!requires {
+    std::derived_from<std::remove_pointer_t<To>,
+                      typename std::remove_pointer_t<To>::MessageLite>;
+  });
+#endif
 
 #if PROTOBUF_RTTI
   // RTTI: debug mode only!
-  assert(f == nullptr || dynamic_cast<To>(f) != nullptr);
+  assert(from == nullptr || dynamic_cast<To*>(from) != nullptr);
 #endif
+}
+
+template <typename To, typename From>
+inline To DownCast(From* f) {
+  AssertDownCast<std::remove_pointer_t<To>>(f);
   return static_cast<To>(f);
 }
 
 template <typename ToRef, typename From>
 inline ToRef DownCast(From& f) {
-  using To = typename std::remove_reference<ToRef>::type;
-  static_assert(std::is_base_of<From, To>::value, "illegal DownCast");
-
-#if PROTOBUF_RTTI
-  // RTTI: debug mode only!
-  assert(dynamic_cast<To*>(&f) != nullptr);
-#endif
-  return *static_cast<To*>(&f);
+  AssertDownCast<std::remove_reference_t<ToRef>>(&f);
+  return static_cast<ToRef>(f);
 }
 
 // Looks up the name of `T` via RTTI, if RTTI is available.
@@ -314,6 +320,8 @@ inline void PrefetchToLocalCache(const void* ptr) {
   absl::PrefetchToLocalCache(ptr);
 }
 
+constexpr bool IsOss() { return true; }
+
 }  // namespace internal
 }  // namespace protobuf
 }  // namespace google
diff --git a/src/google/protobuf/port_def.inc b/src/google/protobuf/port_def.inc
index 2b1371865e..1e05aad179 100644
--- a/src/google/protobuf/port_def.inc
+++ b/src/google/protobuf/port_def.inc
@@ -67,27 +67,6 @@
 // - MSVC: https://docs.microsoft.com/en-us/visualstudio/releases/2019/release-notes-history
 //         https://docs.microsoft.com/en-us/visualstudio/releasenotes/vs2017-relnotes-history
 
-// Portable PROTOBUF_BUILTIN_BSWAPxx definitions
-// Code must check for availability, e.g.: `defined(PROTOBUF_BUILTIN_BSWAP32)`
-#ifdef PROTOBUF_BUILTIN_BSWAP16
-#error PROTOBUF_BUILTIN_BSWAP16 was previously defined
-#endif
-#ifdef PROTOBUF_BUILTIN_BSWAP32
-#error PROTOBUF_BUILTIN_BSWAP32 was previously defined
-#endif
-#ifdef PROTOBUF_BUILTIN_BSWAP64
-#error PROTOBUF_BUILTIN_BSWAP64 was previously defined
-#endif
-#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap16)
-#define PROTOBUF_BUILTIN_BSWAP16(x) __builtin_bswap16(x)
-#endif
-#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap32)
-#define PROTOBUF_BUILTIN_BSWAP32(x) __builtin_bswap32(x)
-#endif
-#if defined(__GNUC__) || ABSL_HAVE_BUILTIN(__builtin_bswap64)
-#define PROTOBUF_BUILTIN_BSWAP64(x) __builtin_bswap64(x)
-#endif
-
 // Portable check for gcc-style atomic built-ins
 #if ABSL_HAVE_BUILTIN(__atomic_load_n)
 #define PROTOBUF_BUILTIN_ATOMIC 1
@@ -424,39 +403,6 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #error PROTOBUF_FORCE_ALLOCATION_ON_CONSTRUCTION was previously defined
 #endif
 
-// Specify memory alignment for structs, classes, etc.
-// Use like:
-//   class PROTOBUF_ALIGNAS(16) MyClass { ... }
-//   PROTOBUF_ALIGNAS(16) int array[4];
-//
-// In most places you can use the C++11 keyword "alignas", which is preferred.
-//
-// But compilers have trouble mixing __attribute__((...)) syntax with
-// alignas(...) syntax.
-//
-// Doesn't work in clang or gcc:
-//   struct alignas(16) __attribute__((packed)) S { char c; };
-// Works in clang but not gcc:
-//   struct __attribute__((packed)) alignas(16) S2 { char c; };
-// Works in clang and gcc:
-//   struct alignas(16) S3 { char c; } __attribute__((packed));
-//
-// There are also some attributes that must be specified *before* a class
-// definition: visibility (used for exporting functions/classes) is one of
-// these attributes. This means that it is not possible to use alignas() with a
-// class that is marked as exported.
-#ifdef PROTOBUF_ALIGNAS
-#error PROTOBUF_ALIGNAS was previously defined
-#endif
-#if defined(_MSC_VER)
-#define PROTOBUF_ALIGNAS(byte_alignment) __declspec(align(byte_alignment))
-#elif defined(__GNUC__)
-#define PROTOBUF_ALIGNAS(byte_alignment) \
-  __attribute__((aligned(byte_alignment)))
-#else
-#define PROTOBUF_ALIGNAS(byte_alignment) alignas(byte_alignment)
-#endif
-
 #ifdef PROTOBUF_THREAD_LOCAL
 #error PROTOBUF_THREAD_LOCAL was previously defined
 #endif
@@ -618,13 +564,6 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #define PROTOBUF_TSAN_DECLARE_MEMBER
 #endif
 
-#ifdef PROTOBUF_USE_TABLE_PARSER_ON_REFLECTION
-#error PROTOBUF_USE_TABLE_PARSER_ON_REFLECTION was previously defined
-#endif
-#if !defined(PROTOBUF_TEMPORARY_DISABLE_TABLE_PARSER_ON_REFLECTION)
-#define PROTOBUF_USE_TABLE_PARSER_ON_REFLECTION 1
-#endif  // PROTOBUF_ENABLE_FORCE_ALLOCATION_ON_CONSTRUCTION
-
 // Note that this is performance sensitive: changing the parameters will change
 // the registers used by the ABI calling convention, which subsequently affects
 // register selection logic inside the function.
@@ -940,8 +879,6 @@ static_assert(PROTOBUF_ABSL_MIN(20230125, 3),
 #define PROTOBUF_DEBUG false
 #endif
 
-#define PROTO2_IS_OSS true
-
 #ifdef PROTOBUF_NO_THREADLOCAL
 #error PROTOBUF_NO_THREADLOCAL was previously defined
 #endif
diff --git a/src/google/protobuf/port_undef.inc b/src/google/protobuf/port_undef.inc
index 93c13dfdbf..9d72db2f52 100644
--- a/src/google/protobuf/port_undef.inc
+++ b/src/google/protobuf/port_undef.inc
@@ -16,9 +16,6 @@
 
 #undef PROTOBUF_POISON_MEMORY_REGION
 #undef PROTOBUF_UNPOISON_MEMORY_REGION
-#undef PROTOBUF_BUILTIN_BSWAP16
-#undef PROTOBUF_BUILTIN_BSWAP32
-#undef PROTOBUF_BUILTIN_BSWAP64
 #undef PROTOBUF_BUILTIN_ATOMIC
 #undef PROTOBUF_GNUC_MIN
 #undef PROTOBUF_CLANG_MIN
@@ -53,7 +50,6 @@
 #undef PROTOBUF_ASSUME
 #undef PROTOBUF_EXPORT_TEMPLATE_DECLARE
 #undef PROTOBUF_EXPORT_TEMPLATE_DEFINE
-#undef PROTOBUF_ALIGNAS
 #undef PROTOBUF_THREAD_LOCAL
 #undef PROTOBUF_CONSTINIT
 #undef PROTOBUF_CONSTEXPR
@@ -68,14 +64,12 @@
 #undef PROTOBUF_MSAN
 #undef PROTOBUF_TSAN
 #undef PROTOBUF_TSAN_DECLARE_MEMBER
-#undef PROTOBUF_USE_TABLE_PARSER_ON_REFLECTION
 #undef PROTOBUF_BUILTIN_CONSTANT_P
 #undef PROTOBUF_DESCRIPTOR_WEAK_MESSAGES_ALLOWED
 #undef PROTOBUF_PREFETCH_PARSE_TABLE
 #undef PROTOBUF_PREFETCH_WITH_OFFSET
 #undef PROTOBUF_TC_PARAM_DECL
 #undef PROTOBUF_DEBUG
-#undef PROTO2_IS_OSS
 #undef PROTOBUF_NO_THREADLOCAL
 
 #ifdef PROTOBUF_FUTURE_BREAKING_CHANGES
diff --git a/src/google/protobuf/reflection_visit_field_info.h b/src/google/protobuf/reflection_visit_field_info.h
index bca311a4f8..29056bc9da 100644
--- a/src/google/protobuf/reflection_visit_field_info.h
+++ b/src/google/protobuf/reflection_visit_field_info.h
@@ -200,10 +200,10 @@ struct DynamicExtensionInfoHelper {
   }
 
   static const Message& GetMessage(const Extension& ext) {
-    return DownCast<const Message&>(*ext.message_value);
+    return DownCastToMessage(*ext.message_value);
   }
   static Message& MutableMessage(Extension& ext) {
-    return DownCast<Message&>(*ext.message_value);
+    return DownCastToMessage(*ext.message_value);
   }
   static void ClearMessage(Extension& ext) {
     ext.is_cleared = true;
@@ -212,18 +212,18 @@ struct DynamicExtensionInfoHelper {
 
   static const Message& GetLazyMessage(const Extension& ext,
                                        const Message& prototype, Arena* arena) {
-    return DownCast<const Message&>(
+    return DownCastToMessage(
         ext.lazymessage_value->GetMessage(prototype, arena));
   }
   static const Message& GetLazyMessageIgnoreUnparsed(const Extension& ext,
                                                      const Message& prototype,
                                                      Arena* arena) {
-    return DownCast<const Message&>(
+    return DownCastToMessage(
         ext.lazymessage_value->GetMessageIgnoreUnparsed(prototype, arena));
   }
   static Message& MutableLazyMessage(Extension& ext, const Message& prototype,
                                      Arena* arena) {
-    return DownCast<Message&>(
+    return DownCastToMessage(
         *ext.lazymessage_value->MutableMessage(prototype, arena));
   }
   static void ClearLazyMessage(Extension& ext) {
diff --git a/src/google/protobuf/reflection_visit_fields.h b/src/google/protobuf/reflection_visit_fields.h
index 0e3acb0e75..e554a76ef9 100644
--- a/src/google/protobuf/reflection_visit_fields.h
+++ b/src/google/protobuf/reflection_visit_fields.h
@@ -422,7 +422,7 @@ void ReflectionVisit::VisitMessageFields(const Message& message,
                              FieldDescriptor::CPPTYPE_MESSAGE) {
           if constexpr (info.is_repeated) {
             for (const auto& it : info.Get()) {
-              func(DownCast<const Message&>(it));
+              func(DownCastToMessage(it));
             }
           } else {
             func(info.Get());
@@ -452,7 +452,7 @@ void ReflectionVisit::VisitMessageFields(Message& message, CallbackFn&& func) {
                              FieldDescriptor::CPPTYPE_MESSAGE) {
           if constexpr (info.is_repeated) {
             for (auto& it : info.Mutable()) {
-              func(DownCast<Message&>(it));
+              func(DownCastToMessage(it));
             }
           } else {
             func(info.Mutable());
diff --git a/src/google/protobuf/repeated_field_reflection_unittest.inc b/src/google/protobuf/repeated_field_reflection_unittest.inc
index 97d5c4128e..8e561adbe1 100644
--- a/src/google/protobuf/repeated_field_reflection_unittest.inc
+++ b/src/google/protobuf/repeated_field_reflection_unittest.inc
@@ -91,7 +91,7 @@ TEST(REFLECTION_TEST, RegularFields) {
     EXPECT_EQ(rf_double.Get(i), Func(i, 2));
     EXPECT_EQ(rpf_string.Get(i), StrFunc(i, 5));
     EXPECT_EQ(rpf_foreign_message.Get(i).c(), Func(i, 6));
-    EXPECT_EQ(DownCast<const ForeignMessage*>(&rpf_message.Get(i))->c(),
+    EXPECT_EQ(DownCastToGenerated<ForeignMessage>(&rpf_message.Get(i))->c(),
               Func(i, 6));
 
     // Check gets through mutable objects.
@@ -99,7 +99,7 @@ TEST(REFLECTION_TEST, RegularFields) {
     EXPECT_EQ(mrf_double->Get(i), Func(i, 2));
     EXPECT_EQ(mrpf_string->Get(i), StrFunc(i, 5));
     EXPECT_EQ(mrpf_foreign_message->Get(i).c(), Func(i, 6));
-    EXPECT_EQ(DownCast<const ForeignMessage*>(&mrpf_message->Get(i))->c(),
+    EXPECT_EQ(DownCastToGenerated<ForeignMessage>(&mrpf_message->Get(i))->c(),
               Func(i, 6));
 
     // Check sets through mutable objects.
@@ -111,7 +111,8 @@ TEST(REFLECTION_TEST, RegularFields) {
     EXPECT_EQ(message.repeated_double(i), Func(i, -2));
     EXPECT_EQ(message.repeated_string(i), StrFunc(i, -5));
     EXPECT_EQ(message.repeated_foreign_message(i).c(), Func(i, -6));
-    DownCast<ForeignMessage*>(mrpf_message->Mutable(i))->set_c(Func(i, 7));
+    DownCastToGenerated<ForeignMessage>(mrpf_message->Mutable(i))
+        ->set_c(Func(i, 7));
     EXPECT_EQ(message.repeated_foreign_message(i).c(), Func(i, 7));
   }
 
@@ -271,7 +272,8 @@ TEST(REFLECTION_TEST, RepeatedFieldRefForRegularFields) {
     ForeignMessage scratch_space;
     EXPECT_EQ(rf_foreign_message.Get(i, &scratch_space).c(), Func(i, 6));
     EXPECT_EQ(
-        DownCast<const ForeignMessage&>(rf_message.Get(i, &scratch_space)).c(),
+        DownCastToGenerated<ForeignMessage>(rf_message.Get(i, &scratch_space))
+            .c(),
         Func(i, 6));
 
     // Check gets through mutable objects.
@@ -280,7 +282,8 @@ TEST(REFLECTION_TEST, RepeatedFieldRefForRegularFields) {
     EXPECT_EQ(mrf_string.Get(i), StrFunc(i, 5));
     EXPECT_EQ(mrf_foreign_message.Get(i, &scratch_space).c(), Func(i, 6));
     EXPECT_EQ(
-        DownCast<const ForeignMessage&>(mrf_message.Get(i, &scratch_space)).c(),
+        DownCastToGenerated<ForeignMessage>(mrf_message.Get(i, &scratch_space))
+            .c(),
         Func(i, 6));
 
     // Check sets through mutable objects.
diff --git a/src/google/protobuf/runtime_version.h b/src/google/protobuf/runtime_version.h
index 50dd313c1f..9244839623 100644
--- a/src/google/protobuf/runtime_version.h
+++ b/src/google/protobuf/runtime_version.h
@@ -9,7 +9,19 @@
 #error PROTOBUF_VERSION_SUFFIX was previously defined
 #endif  // PROTOBUF_VERSION_SUFFIX
 
-#define PROTOBUF_VERSION 5028000
-#define PROTOBUF_VERSION_SUFFIX "-dev"
+#ifdef PROTOBUF_OSS_VERSION
+#error PROTOBUF_OSS_VERSION was previously defined
+#endif  // PROTOBUF_OSS_VERSION
+
+#ifdef PROTOBUF_OSS_VERSION_SUFFIX
+#error PROTOBUF_OSS_VERSION_SUFFIX was previously defined
+#endif  // PROTOBUF_OSS_VERSION_SUFFIX
+
+// The OSS versions are not stripped to avoid merging conflicts.
+#define PROTOBUF_OSS_VERSION 5028000
+#define PROTOBUF_OSS_VERSION_SUFFIX "-dev"
+
+#define PROTOBUF_VERSION PROTOBUF_OSS_VERSION
+#define PROTOBUF_VERSION_SUFFIX PROTOBUF_OSS_VERSION_SUFFIX
 
 #endif  // GOOGLE_PROTOBUF_RUNTIME_VERSION_H__
diff --git a/src/google/protobuf/serial_arena.h b/src/google/protobuf/serial_arena.h
index 0ccc410a76..84472df189 100644
--- a/src/google/protobuf/serial_arena.h
+++ b/src/google/protobuf/serial_arena.h
@@ -37,13 +37,10 @@ namespace internal {
 // Arena blocks are variable length malloc-ed objects.  The following structure
 // describes the common header for all blocks.
 struct ArenaBlock {
-  // For the sentry block with zero-size where ptr_, limit_, cleanup_nodes all
-  // point to "this".
-  constexpr ArenaBlock()
-      : next(nullptr), cleanup_nodes(this), size(0) {}
+  // For the sentry block with zero-size where ptr_/limit_ both point to `this`.
+  constexpr ArenaBlock() : next(nullptr), size(0) {}
 
-  ArenaBlock(ArenaBlock* next, size_t size)
-      : next(next), cleanup_nodes(nullptr), size(size) {
+  ArenaBlock(ArenaBlock* next, size_t size) : next(next), size(size) {
     ABSL_DCHECK_GT(size, sizeof(ArenaBlock));
   }
 
@@ -56,7 +53,6 @@ struct ArenaBlock {
   bool IsSentry() const { return size == 0; }
 
   ArenaBlock* const next;
-  void* cleanup_nodes;
   const size_t size;
   // data follows
 };
@@ -86,7 +82,7 @@ class PROTOBUF_EXPORT SerialArena {
   static constexpr size_t kBlockHeaderSize =
       ArenaAlignDefault::Ceil(sizeof(ArenaBlock));
 
-  void CleanupList();
+  void CleanupList() { cleanup_list_.Cleanup(*this); }
   uint64_t SpaceAllocated() const {
     return space_allocated_.load(std::memory_order_relaxed);
   }
@@ -218,7 +214,7 @@ class PROTOBUF_EXPORT SerialArena {
     *out = ret;
     char* next = ret + n;
     set_ptr(next);
-    MaybePrefetchForwards(next);
+    MaybePrefetchData(next);
     return true;
   }
 
@@ -236,27 +232,23 @@ class PROTOBUF_EXPORT SerialArena {
     n = ArenaAlignDefault::Ceil(n);
     char* ret = ArenaAlignAs(align).CeilDefaultAligned(ptr());
     // See the comment in MaybeAllocateAligned re uintptr_t.
-    if (PROTOBUF_PREDICT_FALSE(reinterpret_cast<uintptr_t>(ret) + n +
-                                   cleanup::Size() >
+    if (PROTOBUF_PREDICT_FALSE(reinterpret_cast<uintptr_t>(ret) + n >
                                reinterpret_cast<uintptr_t>(limit_))) {
       return AllocateAlignedWithCleanupFallback(n, align, destructor);
     }
     PROTOBUF_UNPOISON_MEMORY_REGION(ret, n);
     char* next = ret + n;
     set_ptr(next);
-    AddCleanupFromExisting(ret, destructor);
+    AddCleanup(ret, destructor);
     ABSL_DCHECK_GE(limit_, ptr());
-    MaybePrefetchForwards(next);
+    MaybePrefetchData(next);
     return ret;
   }
 
   PROTOBUF_ALWAYS_INLINE
   void AddCleanup(void* elem, void (*destructor)(void*)) {
-    size_t has = static_cast<size_t>(limit_ - ptr());
-    if (PROTOBUF_PREDICT_FALSE(cleanup::Size() > has)) {
-      return AddCleanupFallback(elem, destructor);
-    }
-    AddCleanupFromExisting(elem, destructor);
+    cleanup_list_.Add(elem, destructor, *this);
+    MaybePrefetchCleanup();
   }
 
   ABSL_ATTRIBUTE_RETURNS_NONNULL void* AllocateFromStringBlock();
@@ -265,6 +257,7 @@ class PROTOBUF_EXPORT SerialArena {
 
  private:
   friend class ThreadSafeArena;
+  friend class cleanup::ChunkList;
 
   // See comments for cached_blocks_.
   struct CachedBlock {
@@ -272,8 +265,8 @@ class PROTOBUF_EXPORT SerialArena {
     CachedBlock* next;
   };
 
-  static constexpr ptrdiff_t kPrefetchForwardsDegree = ABSL_CACHELINE_SIZE * 16;
-  static constexpr ptrdiff_t kPrefetchBackwardsDegree = ABSL_CACHELINE_SIZE * 6;
+  static constexpr ptrdiff_t kPrefetchDataDegree = ABSL_CACHELINE_SIZE * 16;
+  static constexpr ptrdiff_t kPrefetchCleanupDegree = ABSL_CACHELINE_SIZE * 6;
 
   // Constructor is private as only New() should be used.
   inline SerialArena(ArenaBlock* b, ThreadSafeArena& parent);
@@ -285,59 +278,41 @@ class PROTOBUF_EXPORT SerialArena {
   bool MaybeAllocateString(void*& p);
   ABSL_ATTRIBUTE_RETURNS_NONNULL void* AllocateFromStringBlockFallback();
 
+  // Prefetch the next prefetch_degree bytes after `prefetch_ptr` and
+  // up to `limit`, if `next` is within prefetch_degree bytes of `prefetch_ptr`.
   PROTOBUF_ALWAYS_INLINE
-  void AddCleanupFromExisting(void* elem, void (*destructor)(void*)) {
-    const size_t cleanup_size = cleanup::Size();
-
-    PROTOBUF_UNPOISON_MEMORY_REGION(limit_ - cleanup_size, cleanup_size);
-    limit_ -= cleanup_size;
-    MaybePrefetchBackwards(limit_);
-    ABSL_DCHECK_GE(limit_, ptr());
-    cleanup::CreateNode(limit_, elem, destructor);
-  }
-
-  // Prefetch the next kPrefetchForwardsDegree bytes after `prefetch_ptr_` and
-  // up to `prefetch_limit_`, if `next` is within kPrefetchForwardsDegree bytes
-  // of `prefetch_ptr_`.
-  PROTOBUF_ALWAYS_INLINE
-  void MaybePrefetchForwards(const char* next) {
-    ABSL_DCHECK(static_cast<const void*>(prefetch_ptr_) == nullptr ||
-                static_cast<const void*>(prefetch_ptr_) >= head());
-    if (PROTOBUF_PREDICT_TRUE(prefetch_ptr_ - next > kPrefetchForwardsDegree))
-      return;
-    if (PROTOBUF_PREDICT_TRUE(prefetch_ptr_ < prefetch_limit_)) {
-      const char* prefetch_ptr = std::max(next, prefetch_ptr_);
+  static const char* MaybePrefetchImpl(const ptrdiff_t prefetch_degree,
+                                       const char* next, const char* limit,
+                                       const char* prefetch_ptr) {
+    if (PROTOBUF_PREDICT_TRUE(prefetch_ptr - next > prefetch_degree))
+      return prefetch_ptr;
+    if (PROTOBUF_PREDICT_TRUE(prefetch_ptr < limit)) {
+      prefetch_ptr = std::max(next, prefetch_ptr);
       ABSL_DCHECK(prefetch_ptr != nullptr);
-      const char* end =
-          std::min(prefetch_limit_, prefetch_ptr + ABSL_CACHELINE_SIZE * 16);
+      const char* end = std::min(limit, prefetch_ptr + prefetch_degree);
       for (; prefetch_ptr < end; prefetch_ptr += ABSL_CACHELINE_SIZE) {
         absl::PrefetchToLocalCacheForWrite(prefetch_ptr);
       }
-      prefetch_ptr_ = prefetch_ptr;
     }
+    return prefetch_ptr;
   }
-
   PROTOBUF_ALWAYS_INLINE
-  // Prefetch up to kPrefetchBackwardsDegree before `prefetch_limit_` and after
-  // `prefetch_ptr_`, if `limit` is within  kPrefetchBackwardsDegree of
-  // `prefetch_limit_`.
-  void MaybePrefetchBackwards(const char* limit) {
-    ABSL_DCHECK(prefetch_limit_ == nullptr ||
-                static_cast<const void*>(prefetch_limit_) <=
-                    static_cast<const void*>(head()->Limit()));
-    if (PROTOBUF_PREDICT_TRUE(limit - prefetch_limit_ >
-                              kPrefetchBackwardsDegree))
-      return;
-    if (PROTOBUF_PREDICT_TRUE(prefetch_limit_ > prefetch_ptr_)) {
-      const char* prefetch_limit = std::min(limit, prefetch_limit_);
-      ABSL_DCHECK_NE(prefetch_limit, nullptr);
-      const char* end =
-          std::max(prefetch_ptr_, prefetch_limit - kPrefetchBackwardsDegree);
-      for (; prefetch_limit > end; prefetch_limit -= ABSL_CACHELINE_SIZE) {
-        absl::PrefetchToLocalCacheForWrite(prefetch_limit);
-      }
-      prefetch_limit_ = prefetch_limit;
-    }
+  void MaybePrefetchData(const char* next) {
+    ABSL_DCHECK(static_cast<const void*>(prefetch_ptr_) == nullptr ||
+                static_cast<const void*>(prefetch_ptr_) >= head());
+    prefetch_ptr_ =
+        MaybePrefetchImpl(kPrefetchDataDegree, next, limit_, prefetch_ptr_);
+  }
+  PROTOBUF_ALWAYS_INLINE
+  void MaybePrefetchCleanup() {
+    ABSL_DCHECK(static_cast<const void*>(cleanup_list_.prefetch_ptr_) ==
+                    nullptr ||
+                static_cast<const void*>(cleanup_list_.prefetch_ptr_) >=
+                    cleanup_list_.head_);
+    cleanup_list_.prefetch_ptr_ = MaybePrefetchImpl(
+        kPrefetchCleanupDegree, reinterpret_cast<char*>(cleanup_list_.next_),
+        reinterpret_cast<char*>(cleanup_list_.limit_),
+        cleanup_list_.prefetch_ptr_);
   }
 
   // Creates a new SerialArena inside mem using the remaining memory as for
@@ -385,7 +360,6 @@ class PROTOBUF_EXPORT SerialArena {
     set_ptr(ptr);
     prefetch_ptr_ = ptr;
     limit_ = limit;
-    prefetch_limit_ = limit;
   }
 
   void* AllocateAlignedFallback(size_t n);
@@ -405,10 +379,11 @@ class PROTOBUF_EXPORT SerialArena {
   // Limiting address up to which memory can be allocated from the head block.
   char* limit_ = nullptr;
   // Current prefetch positions. Data from `ptr_` up to but not including
-  // `prefetch_ptr_` is software prefetched. Similarly, data from `limit_` down
-  // to but not including `prefetch_limit_` is software prefetched.
+  // `prefetch_ptr_` is software prefetched.
   const char* prefetch_ptr_ = nullptr;
-  const char* prefetch_limit_ = nullptr;
+
+  // Chunked linked list for managing cleanup for arena elements.
+  cleanup::ChunkList cleanup_list_;
 
   // The active string block.
   std::atomic<StringBlock*> string_block_{nullptr};
diff --git a/src/google/protobuf/source_context.pb.cc b/src/google/protobuf/source_context.pb.cc
index 3820c034d3..3d129e5b1a 100644
--- a/src/google/protobuf/source_context.pb.cc
+++ b/src/google/protobuf/source_context.pb.cc
@@ -243,19 +243,20 @@ PROTOBUF_NOINLINE void SourceContext::Clear() {
 }
 
 ::size_t SourceContext::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.SourceContext)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.SourceContext)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // string file_name = 1;
-  if (!this->_internal_file_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_file_name());
+   {
+    // string file_name = 1;
+    if (!this->_internal_file_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_file_name());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/src/google/protobuf/struct.pb.cc b/src/google/protobuf/struct.pb.cc
index cefa306e1c..f03af5772c 100644
--- a/src/google/protobuf/struct.pb.cc
+++ b/src/google/protobuf/struct.pb.cc
@@ -396,20 +396,25 @@ PROTOBUF_NOINLINE void Struct::Clear() {
 }
 
 ::size_t Struct::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Struct)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Struct)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // map<string, .google.protobuf.Value> fields = 1;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_fields_size());
-  for (const auto& entry : _internal_fields()) {
-    total_size += _pbi::MapEntryFuncs<std::string, ::google::protobuf::Value,
-                                   _pbi::WireFormatLite::TYPE_STRING,
-                                   _pbi::WireFormatLite::TYPE_MESSAGE>::ByteSizeLong(entry.first, entry.second);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // map<string, .google.protobuf.Value> fields = 1;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_fields_size());
+      for (const auto& entry : _internal_fields()) {
+        total_size += _pbi::MapEntryFuncs<std::string, ::google::protobuf::Value,
+                                       _pbi::WireFormatLite::TYPE_STRING,
+                                       _pbi::WireFormatLite::TYPE_MESSAGE>::ByteSizeLong(entry.first, entry.second);
+      }
+    }
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
@@ -729,12 +734,12 @@ PROTOBUF_NOINLINE void Value::Clear() {
 }
 
 ::size_t Value::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Value)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Value)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
   switch (kind_case()) {
     // .google.protobuf.NullValue null_value = 1;
@@ -1002,18 +1007,23 @@ PROTOBUF_NOINLINE void ListValue::Clear() {
 }
 
 ::size_t ListValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.ListValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.ListValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.Value values = 1;
-  total_size += 1UL * this->_internal_values_size();
-  for (const auto& msg : this->_internal_values()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.Value values = 1;
+     {
+      total_size += 1UL * this->_internal_values_size();
+      for (const auto& msg : this->_internal_values()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
diff --git a/src/google/protobuf/text_format.cc b/src/google/protobuf/text_format.cc
index 3f4d3ba260..71b7ed6d03 100644
--- a/src/google/protobuf/text_format.cc
+++ b/src/google/protobuf/text_format.cc
@@ -94,27 +94,68 @@ namespace internal {
 const char kDebugStringSilentMarker[] = "";
 const char kDebugStringSilentMarkerForDetection[] = "\t ";
 
-// Controls insertion of kDebugStringSilentMarker into DebugString() output.
-PROTOBUF_EXPORT std::atomic<bool> enable_debug_text_format_marker;
-
 // Controls insertion of a marker making debug strings non-parseable, and
-// redacting annotated fields.
-PROTOBUF_EXPORT std::atomic<bool> enable_debug_text_redaction{true};
+// redacting annotated fields in Protobuf's DebugString APIs.
+PROTOBUF_EXPORT std::atomic<bool> enable_debug_string_safe_format{false};
 
 int64_t GetRedactedFieldCount() {
   return num_redacted_field.load(std::memory_order_relaxed);
 }
+
+enum class Option { kNone, kShort, kUTF8 };
+
+std::string StringifyMessage(const Message& message, Option option,
+                             FieldReporterLevel reporter_level,
+                             bool enable_safe_format) {
+  // Indicate all scoped reflection calls are from DebugString function.
+  ScopedReflectionMode scope(ReflectionMode::kDebugString);
+
+  TextFormat::Printer printer;
+  internal::FieldReporterLevel reporter = reporter_level;
+  switch (option) {
+    case Option::kShort:
+      printer.SetSingleLineMode(true);
+      break;
+    case Option::kUTF8:
+      printer.SetUseUtf8StringEscaping(true);
+      break;
+    case Option::kNone:
+      break;
+  }
+  printer.SetExpandAny(true);
+  printer.SetRedactDebugString(enable_safe_format);
+  printer.SetRandomizeDebugString(enable_safe_format);
+  printer.SetReportSensitiveFields(reporter);
+  std::string result;
+  printer.PrintToString(message, &result);
+
+  if (option == Option::kShort) {
+    TrimTrailingSpace(result);
+  }
+
+  return result;
+}
+
+PROTOBUF_EXPORT std::string StringifyMessage(const Message& message) {
+  return StringifyMessage(message, Option::kNone,
+                          FieldReporterLevel::kAbslStringify, true);
+}
 }  // namespace internal
 
 std::string Message::DebugString() const {
+  bool enable_safe_format =
+      internal::enable_debug_string_safe_format.load(std::memory_order_relaxed);
+  if (enable_safe_format) {
+    return StringifyMessage(*this, internal::Option::kNone,
+                            FieldReporterLevel::kDebugString, true);
+  }
   // Indicate all scoped reflection calls are from DebugString function.
   ScopedReflectionMode scope(ReflectionMode::kDebugString);
   std::string debug_string;
 
   TextFormat::Printer printer;
   printer.SetExpandAny(true);
-  printer.SetInsertSilentMarker(internal::enable_debug_text_format_marker.load(
-      std::memory_order_relaxed));
+  printer.SetInsertSilentMarker(true);
   printer.SetReportSensitiveFields(FieldReporterLevel::kDebugString);
 
   printer.PrintToString(*this, &debug_string);
@@ -123,6 +164,12 @@ std::string Message::DebugString() const {
 }
 
 std::string Message::ShortDebugString() const {
+  bool enable_safe_format =
+      internal::enable_debug_string_safe_format.load(std::memory_order_relaxed);
+  if (enable_safe_format) {
+    return StringifyMessage(*this, internal::Option::kShort,
+                            FieldReporterLevel::kShortDebugString, true);
+  }
   // Indicate all scoped reflection calls are from DebugString function.
   ScopedReflectionMode scope(ReflectionMode::kDebugString);
   std::string debug_string;
@@ -130,8 +177,7 @@ std::string Message::ShortDebugString() const {
   TextFormat::Printer printer;
   printer.SetSingleLineMode(true);
   printer.SetExpandAny(true);
-  printer.SetInsertSilentMarker(internal::enable_debug_text_format_marker.load(
-      std::memory_order_relaxed));
+  printer.SetInsertSilentMarker(true);
   printer.SetReportSensitiveFields(FieldReporterLevel::kShortDebugString);
 
   printer.PrintToString(*this, &debug_string);
@@ -141,6 +187,12 @@ std::string Message::ShortDebugString() const {
 }
 
 std::string Message::Utf8DebugString() const {
+  bool enable_safe_format =
+      internal::enable_debug_string_safe_format.load(std::memory_order_relaxed);
+  if (enable_safe_format) {
+    return StringifyMessage(*this, internal::Option::kUTF8,
+                            FieldReporterLevel::kUtf8DebugString, true);
+  }
   // Indicate all scoped reflection calls are from DebugString function.
   ScopedReflectionMode scope(ReflectionMode::kDebugString);
   std::string debug_string;
@@ -148,8 +200,7 @@ std::string Message::Utf8DebugString() const {
   TextFormat::Printer printer;
   printer.SetUseUtf8StringEscaping(true);
   printer.SetExpandAny(true);
-  printer.SetInsertSilentMarker(internal::enable_debug_text_format_marker.load(
-      std::memory_order_relaxed));
+  printer.SetInsertSilentMarker(true);
   printer.SetReportSensitiveFields(FieldReporterLevel::kUtf8DebugString);
 
   printer.PrintToString(*this, &debug_string);
@@ -159,55 +210,14 @@ std::string Message::Utf8DebugString() const {
 
 void Message::PrintDebugString() const { printf("%s", DebugString().c_str()); }
 
-namespace internal {
-
-enum class Option { kNone, kShort, kUTF8 };
-
-std::string StringifyMessage(const Message& message, Option option) {
-  // Indicate all scoped reflection calls are from DebugString function.
-  ScopedReflectionMode scope(ReflectionMode::kDebugString);
-
-  TextFormat::Printer printer;
-  internal::FieldReporterLevel reporter = FieldReporterLevel::kAbslStringify;
-  switch (option) {
-    case Option::kShort:
-      printer.SetSingleLineMode(true);
-      reporter = FieldReporterLevel::kShortFormat;
-      break;
-    case Option::kUTF8:
-      printer.SetUseUtf8StringEscaping(true);
-      reporter = FieldReporterLevel::kUtf8Format;
-      break;
-    case Option::kNone:
-      break;
-  }
-  printer.SetExpandAny(true);
-  printer.SetRedactDebugString(
-      internal::enable_debug_text_redaction.load(std::memory_order_relaxed));
-  printer.SetRandomizeDebugString(true);
-  printer.SetReportSensitiveFields(reporter);
-  std::string result;
-  printer.PrintToString(message, &result);
-
-  if (option == Option::kShort) {
-    TrimTrailingSpace(result);
-  }
-
-  return result;
-}
-
-PROTOBUF_EXPORT std::string StringifyMessage(const Message& message) {
-  return StringifyMessage(message, Option::kNone);
-}
-
-}  // namespace internal
-
 PROTOBUF_EXPORT std::string ShortFormat(const Message& message) {
-  return internal::StringifyMessage(message, internal::Option::kShort);
+  return internal::StringifyMessage(message, internal::Option::kShort,
+                                    FieldReporterLevel::kShortFormat, true);
 }
 
 PROTOBUF_EXPORT std::string Utf8Format(const Message& message) {
-  return internal::StringifyMessage(message, internal::Option::kUTF8);
+  return internal::StringifyMessage(message, internal::Option::kUTF8,
+                                    FieldReporterLevel::kUtf8Format, true);
 }
 
 
@@ -1358,8 +1368,8 @@ class TextFormat::Parser::ParserImpl {
     return result;
   }
 
-  // Attempts to consume the supplied value. Returns false if a the
-  // token found does not match the value specified.
+  // Attempts to consume the supplied value. Returns false if the token found
+  // does not match the value specified.
   bool TryConsume(const std::string& value) {
     if (tokenizer_.current().text == value) {
       tokenizer_.Next();
diff --git a/src/google/protobuf/text_format.h b/src/google/protobuf/text_format.h
index 05ae3508a2..da891beb97 100644
--- a/src/google/protobuf/text_format.h
+++ b/src/google/protobuf/text_format.h
@@ -44,9 +44,7 @@ namespace internal {
 PROTOBUF_EXPORT extern const char kDebugStringSilentMarker[1];
 PROTOBUF_EXPORT extern const char kDebugStringSilentMarkerForDetection[3];
 
-PROTOBUF_EXPORT extern std::atomic<bool> enable_debug_text_format_marker;
-PROTOBUF_EXPORT extern std::atomic<bool> enable_debug_text_detection;
-PROTOBUF_EXPORT extern std::atomic<bool> enable_debug_text_redaction;
+PROTOBUF_EXPORT extern std::atomic<bool> enable_debug_string_safe_format;
 PROTOBUF_EXPORT int64_t GetRedactedFieldCount();
 PROTOBUF_EXPORT bool ShouldRedactField(const FieldDescriptor* field);
 
@@ -88,9 +86,13 @@ namespace internal {
 // Enum used to set printing options for StringifyMessage.
 PROTOBUF_EXPORT enum class Option;
 
-// Converts a protobuf message to a string with redaction enabled.
+// Converts a protobuf message to a string. If enable_safe_format is true,
+// sensitive fields are redacted, and a per-process randomized prefix is
+// inserted.
 PROTOBUF_EXPORT std::string StringifyMessage(const Message& message,
-                                             Option option);
+                                             Option option,
+                                             FieldReporterLevel reporter_level,
+                                             bool enable_safe_format);
 
 class UnsetFieldsMetadataTextFormatTestUtil;
 class UnsetFieldsMetadataMessageDifferencerTestUtil;
@@ -453,8 +455,9 @@ class PROTOBUF_EXPORT TextFormat {
     friend std::string Message::DebugString() const;
     friend std::string Message::ShortDebugString() const;
     friend std::string Message::Utf8DebugString() const;
-    friend std::string internal::StringifyMessage(const Message& message,
-                                                  internal::Option option);
+    friend std::string internal::StringifyMessage(
+        const Message& message, internal::Option option,
+        internal::FieldReporterLevel reporter_level, bool enable_safe_format);
 
     // Sets whether silent markers will be inserted.
     void SetInsertSilentMarker(bool v) { insert_silent_marker_ = v; }
diff --git a/src/google/protobuf/text_format_unittest.cc b/src/google/protobuf/text_format_unittest.cc
index 02b1d38167..886d65695a 100644
--- a/src/google/protobuf/text_format_unittest.cc
+++ b/src/google/protobuf/text_format_unittest.cc
@@ -93,7 +93,20 @@ constexpr absl::string_view kEscapeTestStringEscaped =
 
 constexpr absl::string_view value_replacement = "\\[REDACTED\\]";
 
-class TextFormatTest : public testing::Test {
+class TextFormatTestBase : public testing::Test {
+ public:
+  void SetUp() override {
+    single_line_debug_format_prefix_ = "";
+    multi_line_debug_format_prefix_ = proto_.DebugString();
+  }
+
+ protected:
+  unittest::TestAllTypes proto_;
+  std::string single_line_debug_format_prefix_;
+  std::string multi_line_debug_format_prefix_;
+};
+
+class TextFormatTest : public TextFormatTestBase {
  public:
   static void SetUpTestSuite() {
     ABSL_CHECK_OK(File::GetContents(
@@ -108,8 +121,6 @@ class TextFormatTest : public testing::Test {
  protected:
   // Text format read from text_format_unittest_data.txt.
   const std::string proto_text_format_;
-  unittest::TestAllTypes proto_;
-
  private:
   static std::string static_proto_text_format_;
 };
@@ -157,8 +168,8 @@ TEST_F(TextFormatTest, ShortDebugString) {
   proto_.mutable_optional_foreign_message();
 
   EXPECT_EQ(proto_.ShortDebugString(),
-            absl::StrCat("optional_int32: ", kDebugStringSilentMarker,
-                         "1 "
+            absl::StrCat(single_line_debug_format_prefix_,
+                         "optional_int32: 1 "
                          "optional_string: \"hello\" "
                          "optional_nested_message { bb: 2 } "
                          "optional_foreign_message { }"));
@@ -337,8 +348,8 @@ TEST_F(TextFormatTest, StringEscape) {
 
   // Hardcode a correct value to test against.
   std::string correct_string =
-      absl::StrCat("optional_string: ", kDebugStringSilentMarker,
-                   kEscapeTestStringEscaped, "\n");
+      absl::StrCat(multi_line_debug_format_prefix_,
+                   "optional_string: ", kEscapeTestStringEscaped, "\n");
 
   // Compare.
   EXPECT_EQ(correct_string, debug_string);
@@ -346,8 +357,9 @@ TEST_F(TextFormatTest, StringEscape) {
   // the protocol buffer contains no UTF-8 text.
   EXPECT_EQ(correct_string, utf8_debug_string);
 
-  std::string expected_short_debug_string = absl::StrCat(
-      "optional_string: ", kDebugStringSilentMarker, kEscapeTestStringEscaped);
+  std::string expected_short_debug_string =
+      absl::StrCat(single_line_debug_format_prefix_,
+                   "optional_string: ", kEscapeTestStringEscaped);
   EXPECT_EQ(expected_short_debug_string, proto_.ShortDebugString());
 }
 
@@ -362,12 +374,12 @@ TEST_F(TextFormatTest, Utf8DebugString) {
 
   // Hardcode a correct value to test against.
   std::string correct_utf8_string =
-      absl::StrCat("optional_string: ", kDebugStringSilentMarker,
-                   "\"\350\260\267\346\255\214\"\n"
+      absl::StrCat(multi_line_debug_format_prefix_,
+                   "optional_string: \"\350\260\267\346\255\214\"\n"
                    "optional_bytes: \"\\350\\260\\267\\346\\255\\214\"\n");
   std::string correct_string =
-      absl::StrCat("optional_string: ", kDebugStringSilentMarker,
-                   "\"\\350\\260\\267\\346\\255\\214\"\n"
+      absl::StrCat(multi_line_debug_format_prefix_,
+                   "optional_string: \"\\350\\260\\267\\346\\255\\214\"\n"
                    "optional_bytes: \"\\350\\260\\267\\346\\255\\214\"\n");
 
   // Compare.
@@ -404,8 +416,9 @@ TEST_F(TextFormatTest, PrintUnknownFields) {
   unknown_fields->AddVarint(8, 2);
   unknown_fields->AddVarint(8, 3);
 
-  EXPECT_EQ(absl::StrCat("5: ", kDebugStringSilentMarker,
-                         "1\n"
+  std::string message_text;
+  TextFormat::PrintToString(message, &message_text);
+  EXPECT_EQ(absl::StrCat("5: 1\n"
                          "5: 0x00000002\n"
                          "5: 0x0000000000000003\n"
                          "5: \"4\"\n"
@@ -415,7 +428,7 @@ TEST_F(TextFormatTest, PrintUnknownFields) {
                          "8: 1\n"
                          "8: 2\n"
                          "8: 3\n"),
-            message.DebugString());
+            message_text);
 
   EXPECT_THAT(absl::StrCat(message), testing::MatchesRegex(absl::Substitute(
                                          "5: UNKNOWN_VARINT $0\n"
@@ -1012,8 +1025,8 @@ TEST_F(TextFormatTest, PrintUnknownEnumFieldProto3) {
   proto.add_repeated_nested_enum(
       static_cast<proto3_unittest::TestAllTypes::NestedEnum>(-2147483648));
 
-  EXPECT_EQ(absl::StrCat("repeated_nested_enum: ", kDebugStringSilentMarker,
-                         "10\n"
+  EXPECT_EQ(absl::StrCat(multi_line_debug_format_prefix_,
+                         "repeated_nested_enum: 10\n"
                          "repeated_nested_enum: -10\n"
                          "repeated_nested_enum: 2147483647\n"
                          "repeated_nested_enum: -2147483648\n"),
@@ -1464,8 +1477,8 @@ TEST_F(TextFormatTest, PrintExotic) {
   //   have this problem, so we switched to that instead.
 
   EXPECT_EQ(
-      absl::StrCat("repeated_int64: ", kDebugStringSilentMarker,
-                   "-9223372036854775808\n"
+      absl::StrCat(multi_line_debug_format_prefix_,
+                   "repeated_int64: -9223372036854775808\n"
                    "repeated_uint64: 18446744073709551615\n"
                    "repeated_double: 123.456\n"
                    "repeated_double: 1.23e+21\n"
@@ -1524,8 +1537,8 @@ TEST_F(TextFormatTest, PrintFloatPrecision) {
   message.add_repeated_double(1.2345678987654e100);
   message.add_repeated_double(1.23456789876543e100);
 
-  EXPECT_EQ(absl::StrCat("repeated_float: ", kDebugStringSilentMarker,
-                         "1\n"
+  EXPECT_EQ(absl::StrCat(multi_line_debug_format_prefix_,
+                         "repeated_float: 1\n"
                          "repeated_float: 1.2\n"
                          "repeated_float: 1.23\n"
                          "repeated_float: 1.234\n"
diff --git a/src/google/protobuf/thread_safe_arena.h b/src/google/protobuf/thread_safe_arena.h
index 93dc6a7cfa..2065ee98e8 100644
--- a/src/google/protobuf/thread_safe_arena.h
+++ b/src/google/protobuf/thread_safe_arena.h
@@ -20,6 +20,7 @@
 #include "absl/synchronization/mutex.h"
 #include "google/protobuf/arena_align.h"
 #include "google/protobuf/arena_allocation_policy.h"
+#include "google/protobuf/arena_cleanup.h"
 #include "google/protobuf/arenaz_sampler.h"
 #include "google/protobuf/port.h"
 #include "google/protobuf/serial_arena.h"
@@ -109,6 +110,7 @@ class PROTOBUF_EXPORT ThreadSafeArena {
   friend class TcParser;
   friend class SerialArena;
   friend struct SerialArenaChunkHeader;
+  friend class cleanup::ChunkList;
   static uint64_t GetNextLifeCycleId();
 
   class SerialArenaChunk;
@@ -207,7 +209,7 @@ class PROTOBUF_EXPORT ThreadSafeArena {
   // Releases all memory except the first block which it returns. The first
   // block might be owned by the user and thus need some extra checks before
   // deleting.
-  SizedPtr Free(size_t* space_allocated);
+  SizedPtr Free();
 
   // ThreadCache is accessed very frequently, so we align it such that it's
   // located within a single cache line.
diff --git a/src/google/protobuf/timestamp.pb.cc b/src/google/protobuf/timestamp.pb.cc
index 188c3e9c73..ab1e8af510 100644
--- a/src/google/protobuf/timestamp.pb.cc
+++ b/src/google/protobuf/timestamp.pb.cc
@@ -245,26 +245,27 @@ PROTOBUF_NOINLINE void Timestamp::Clear() {
 }
 
 ::size_t Timestamp::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Timestamp)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Timestamp)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
-
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // int64 seconds = 1;
-  if (this->_internal_seconds() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
-        this->_internal_seconds());
-  }
+  (void)cached_has_bits;
 
-  // int32 nanos = 2;
-  if (this->_internal_nanos() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
-        this->_internal_nanos());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // int64 seconds = 1;
+    if (this->_internal_seconds() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
+          this->_internal_seconds());
+    }
+    // int32 nanos = 2;
+    if (this->_internal_nanos() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+          this->_internal_nanos());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/src/google/protobuf/type.pb.cc b/src/google/protobuf/type.pb.cc
index eaf4384bc2..a6a22cf368 100644
--- a/src/google/protobuf/type.pb.cc
+++ b/src/google/protobuf/type.pb.cc
@@ -685,55 +685,66 @@ PROTOBUF_NOINLINE void Type::Clear() {
 }
 
 ::size_t Type::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Type)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Type)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.Field fields = 2;
-  total_size += 1UL * this->_internal_fields_size();
-  for (const auto& msg : this->_internal_fields()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated string oneofs = 3;
-  total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_oneofs().size());
-  for (int i = 0, n = _internal_oneofs().size(); i < n; ++i) {
-    total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
-        _internal_oneofs().Get(i));
-  }
-  // repeated .google.protobuf.Option options = 4;
-  total_size += 1UL * this->_internal_options_size();
-  for (const auto& msg : this->_internal_options()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.Field fields = 2;
+     {
+      total_size += 1UL * this->_internal_fields_size();
+      for (const auto& msg : this->_internal_fields()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated string oneofs = 3;
+     {
+      total_size += 1 * ::google::protobuf::internal::FromIntSize(_internal_oneofs().size());
+      for (int i = 0, n = _internal_oneofs().size(); i < n; ++i) {
+        total_size += ::google::protobuf::internal::WireFormatLite::StringSize(
+            _internal_oneofs().Get(i));
+      }
+    }
+    // repeated .google.protobuf.Option options = 4;
+     {
+      total_size += 1UL * this->_internal_options_size();
+      for (const auto& msg : this->_internal_options()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-
-  // string edition = 7;
-  if (!this->_internal_edition().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_edition());
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // string edition = 7;
+    if (!this->_internal_edition().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_edition());
+    }
   }
-
-  // .google.protobuf.SourceContext source_context = 5;
-  cached_has_bits = _impl_._has_bits_[0];
-  if (cached_has_bits & 0x00000001u) {
-    total_size +=
-        1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_context_);
+   {
+    // .google.protobuf.SourceContext source_context = 5;
+    cached_has_bits = _impl_._has_bits_[0];
+    if (cached_has_bits & 0x00000001u) {
+      total_size +=
+          1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_context_);
+    }
   }
-
-  // .google.protobuf.Syntax syntax = 6;
-  if (this->_internal_syntax() != 0) {
-    total_size += 1 +
-                  ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+   {
+    // .google.protobuf.Syntax syntax = 6;
+    if (this->_internal_syntax() != 0) {
+      total_size += 1 +
+                    ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1111,72 +1122,70 @@ PROTOBUF_NOINLINE void Field::Clear() {
 }
 
 ::size_t Field::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Field)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Field)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
-
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.Option options = 9;
-  total_size += 1UL * this->_internal_options_size();
-  for (const auto& msg : this->_internal_options()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // string name = 4;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
-  }
-
-  // string type_url = 6;
-  if (!this->_internal_type_url().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_type_url());
-  }
-
-  // string json_name = 10;
-  if (!this->_internal_json_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_json_name());
-  }
-
-  // string default_value = 11;
-  if (!this->_internal_default_value().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_default_value());
-  }
-
-  // .google.protobuf.Field.Kind kind = 1;
-  if (this->_internal_kind() != 0) {
-    total_size += 1 +
-                  ::_pbi::WireFormatLite::EnumSize(this->_internal_kind());
-  }
-
-  // .google.protobuf.Field.Cardinality cardinality = 2;
-  if (this->_internal_cardinality() != 0) {
-    total_size += 1 +
-                  ::_pbi::WireFormatLite::EnumSize(this->_internal_cardinality());
-  }
-
-  // int32 number = 3;
-  if (this->_internal_number() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
-        this->_internal_number());
-  }
+  (void)cached_has_bits;
 
-  // int32 oneof_index = 7;
-  if (this->_internal_oneof_index() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
-        this->_internal_oneof_index());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.Option options = 9;
+     {
+      total_size += 1UL * this->_internal_options_size();
+      for (const auto& msg : this->_internal_options()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-
-  // bool packed = 8;
-  if (this->_internal_packed() != 0) {
-    total_size += 2;
+   {
+    // string name = 4;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // string type_url = 6;
+    if (!this->_internal_type_url().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_type_url());
+    }
+    // string json_name = 10;
+    if (!this->_internal_json_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_json_name());
+    }
+    // string default_value = 11;
+    if (!this->_internal_default_value().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_default_value());
+    }
+    // .google.protobuf.Field.Kind kind = 1;
+    if (this->_internal_kind() != 0) {
+      total_size += 1 +
+                    ::_pbi::WireFormatLite::EnumSize(this->_internal_kind());
+    }
+    // .google.protobuf.Field.Cardinality cardinality = 2;
+    if (this->_internal_cardinality() != 0) {
+      total_size += 1 +
+                    ::_pbi::WireFormatLite::EnumSize(this->_internal_cardinality());
+    }
+    // int32 number = 3;
+    if (this->_internal_number() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+          this->_internal_number());
+    }
+    // int32 oneof_index = 7;
+    if (this->_internal_oneof_index() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+          this->_internal_oneof_index());
+    }
+    // bool packed = 8;
+    if (this->_internal_packed() != 0) {
+      total_size += 2;
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1510,49 +1519,58 @@ PROTOBUF_NOINLINE void Enum::Clear() {
 }
 
 ::size_t Enum::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Enum)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Enum)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.EnumValue enumvalue = 2;
-  total_size += 1UL * this->_internal_enumvalue_size();
-  for (const auto& msg : this->_internal_enumvalue()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // repeated .google.protobuf.Option options = 3;
-  total_size += 1UL * this->_internal_options_size();
-  for (const auto& msg : this->_internal_options()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.EnumValue enumvalue = 2;
+     {
+      total_size += 1UL * this->_internal_enumvalue_size();
+      for (const auto& msg : this->_internal_enumvalue()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
+    // repeated .google.protobuf.Option options = 3;
+     {
+      total_size += 1UL * this->_internal_options_size();
+      for (const auto& msg : this->_internal_options()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-
-  // string edition = 6;
-  if (!this->_internal_edition().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_edition());
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // string edition = 6;
+    if (!this->_internal_edition().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_edition());
+    }
   }
-
-  // .google.protobuf.SourceContext source_context = 4;
-  cached_has_bits = _impl_._has_bits_[0];
-  if (cached_has_bits & 0x00000001u) {
-    total_size +=
-        1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_context_);
+   {
+    // .google.protobuf.SourceContext source_context = 4;
+    cached_has_bits = _impl_._has_bits_[0];
+    if (cached_has_bits & 0x00000001u) {
+      total_size +=
+          1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.source_context_);
+    }
   }
-
-  // .google.protobuf.Syntax syntax = 5;
-  if (this->_internal_syntax() != 0) {
-    total_size += 1 +
-                  ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+   {
+    // .google.protobuf.Syntax syntax = 5;
+    if (this->_internal_syntax() != 0) {
+      total_size += 1 +
+                    ::_pbi::WireFormatLite::EnumSize(this->_internal_syntax());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1801,31 +1819,36 @@ PROTOBUF_NOINLINE void EnumValue::Clear() {
 }
 
 ::size_t EnumValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.EnumValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // repeated .google.protobuf.Option options = 3;
-  total_size += 1UL * this->_internal_options_size();
-  for (const auto& msg : this->_internal_options()) {
-    total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
-  }
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // repeated .google.protobuf.Option options = 3;
+     {
+      total_size += 1UL * this->_internal_options_size();
+      for (const auto& msg : this->_internal_options()) {
+        total_size += ::google::protobuf::internal::WireFormatLite::MessageSize(msg);
+      }
+    }
   }
-
-  // int32 number = 2;
-  if (this->_internal_number() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
-        this->_internal_number());
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
+    // int32 number = 2;
+    if (this->_internal_number() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+          this->_internal_number());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -2047,27 +2070,30 @@ PROTOBUF_NOINLINE void Option::Clear() {
 }
 
 ::size_t Option::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Option)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Option)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  ::_pbi::Prefetch5LinesFrom7Lines(reinterpret_cast<const void*>(this));
-  // string name = 1;
-  if (!this->_internal_name().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_name());
+  ::_pbi::Prefetch5LinesFrom7Lines(
+      reinterpret_cast<const void*>(this));
+   {
+    // string name = 1;
+    if (!this->_internal_name().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_name());
+    }
   }
-
-  // .google.protobuf.Any value = 2;
-  cached_has_bits = _impl_._has_bits_[0];
-  if (cached_has_bits & 0x00000001u) {
-    total_size +=
-        1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.value_);
+   {
+    // .google.protobuf.Any value = 2;
+    cached_has_bits = _impl_._has_bits_[0];
+    if (cached_has_bits & 0x00000001u) {
+      total_size +=
+          1 + ::google::protobuf::internal::WireFormatLite::MessageSize(*_impl_.value_);
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/src/google/protobuf/unittest.proto b/src/google/protobuf/unittest.proto
index 434325f4d1..cb46956d31 100644
--- a/src/google/protobuf/unittest.proto
+++ b/src/google/protobuf/unittest.proto
@@ -198,6 +198,7 @@ enum ForeignEnum {
   FOREIGN_BAR = 5;
   FOREIGN_BAZ = 6;
   FOREIGN_BAX = 32;  // (1 << 32) to generate a 64b bitmask would be incorrect.
+  FOREIGN_LARGE = 123456;  // Large enough to escape the Boxed Integer cache.
 }
 
 message TestReservedFields {
@@ -1225,11 +1226,11 @@ message TestNestedGroupExtensionOuter {
     repeated group Layer2RepeatedGroup = 2 {
       extensions 3
         // NOTE: extension metadata is not supported due to targets such as
-        // `//third_party/protobuf_legacy_opensource/src:shell_scripts_test`,
+        // `//google/protobuf_legacy_opensource/src:shell_scripts_test`,
         // eee https://screenshot.googleplex.com/Axz2QD8nxjdpyFF
         //[metadata = {
         // NOTE: can't write type there due to some clever build gen code at
-        // http://google3/net/proto2/internal/BUILD;l=1247;rcl=411090862
+        // http://google3/google/protobuf/BUILD;l=1247;rcl=411090862
         // type: "protobuf_unittest.TestNestedGroupExtensionInnerExtension",
         // name: "inner",
         // }]
@@ -1737,6 +1738,12 @@ message RedactedFields {
   repeated TestNestedMessageRedaction repeated_unredacted_message = 8;
   map<string, string> map_redacted_string = 9 [debug_redact = true];
   map<string, string> map_unredacted_string = 10;
+  optional string optional_redacted_false_string = 11 [debug_redact = false];
+  extensions 20 to 30;
+}
+
+extend RedactedFields {
+  optional string redacted_extension = 20 [debug_redact = true];
 }
 
 message TestCord{
diff --git a/src/google/protobuf/unittest_custom_options.proto b/src/google/protobuf/unittest_custom_options.proto
index ca6bec7a60..7075012778 100644
--- a/src/google/protobuf/unittest_custom_options.proto
+++ b/src/google/protobuf/unittest_custom_options.proto
@@ -191,6 +191,26 @@ message SettingRealsFromNegativeInts {
   option (double_opt) = -154;
 }
 
+message SettingRealsFromInf {
+  option (float_opt) = inf;
+  option (double_opt) = inf;
+}
+
+message SettingRealsFromNegativeInf {
+  option (float_opt) = -inf;
+  option (double_opt) = -inf;
+}
+
+message SettingRealsFromNan {
+  option (float_opt) = nan;
+  option (double_opt) = nan;
+}
+
+message SettingRealsFromNegativeNan {
+  option (float_opt) = -nan;
+  option (double_opt) = -nan;
+}
+
 // Options of complex message types, themselves combined and extended in
 // various ways.
 
diff --git a/src/google/protobuf/unittest_proto3.proto b/src/google/protobuf/unittest_proto3.proto
index 1c0f65bc9a..d88521afea 100644
--- a/src/google/protobuf/unittest_proto3.proto
+++ b/src/google/protobuf/unittest_proto3.proto
@@ -114,7 +114,7 @@ message TestAllTypes {
   repeated string repeated_string_piece = 54 [ctype = STRING_PIECE];
   repeated string repeated_cord = 55 [ctype = CORD];
 
-  repeated NestedMessage repeated_lazy_message = 57 ;
+  repeated NestedMessage repeated_lazy_message = 57;
 
   oneof oneof_field {
     uint32 oneof_uint32 = 111;
@@ -178,6 +178,7 @@ enum ForeignEnum {
   FOREIGN_FOO = 4;
   FOREIGN_BAR = 5;
   FOREIGN_BAZ = 6;
+  FOREIGN_LARGE = 123456;  // Large enough to escape the Boxed Integer cache.
 }
 
 // TestEmptyMessage is used to test behavior of unknown fields.
@@ -204,3 +205,79 @@ message TestOneof2 {
     BAZ = 3;
   }
 }
+
+// If bool fields are incorrectly assumed to have hasbits, InternalSwap would
+// result in swapping N more 32bit hasbits incorrectly. Considering padding, we
+// need many bool fields to stress this.
+message TestHasbits {
+  bool b1 = 1;
+  bool b2 = 2;
+  bool b3 = 3;
+  bool b4 = 4;
+  bool b5 = 5;
+  bool b6 = 6;
+  bool b7 = 7;
+  bool b8 = 8;
+  bool b9 = 9;
+  bool b10 = 10;
+  bool b11 = 11;
+  bool b12 = 12;
+  bool b13 = 13;
+  bool b14 = 14;
+  bool b15 = 15;
+  bool b16 = 16;
+  bool b17 = 17;
+  bool b18 = 18;
+  bool b19 = 19;
+  bool b20 = 20;
+  bool b21 = 21;
+  bool b22 = 22;
+  bool b23 = 23;
+  bool b24 = 24;
+  bool b25 = 25;
+  bool b26 = 26;
+  bool b27 = 27;
+  bool b28 = 28;
+  bool b29 = 29;
+  bool b30 = 30;
+  bool b31 = 31;
+  bool b32 = 32;
+  bool b33 = 33;
+  bool b34 = 34;
+  bool b35 = 35;
+  bool b36 = 36;
+  bool b37 = 37;
+  bool b38 = 38;
+  bool b39 = 39;
+  bool b40 = 40;
+  bool b41 = 41;
+  bool b42 = 42;
+  bool b43 = 43;
+  bool b44 = 44;
+  bool b45 = 45;
+  bool b46 = 46;
+  bool b47 = 47;
+  bool b48 = 48;
+  bool b49 = 49;
+  bool b50 = 50;
+  bool b51 = 51;
+  bool b52 = 52;
+  bool b53 = 53;
+  bool b54 = 54;
+  bool b55 = 55;
+  bool b56 = 56;
+  bool b57 = 57;
+  bool b58 = 58;
+  bool b59 = 59;
+  bool b60 = 60;
+  bool b61 = 61;
+  bool b62 = 62;
+  bool b63 = 63;
+  bool b64 = 64;
+  bool b65 = 65;
+  bool b66 = 66;
+  bool b67 = 67;
+  bool b68 = 68;
+  bool b69 = 69;
+  TestAllTypes child = 100;
+}
diff --git a/src/google/protobuf/unittest_proto3_arena.proto b/src/google/protobuf/unittest_proto3_arena.proto
index 032ce6ff67..96a9ea85e2 100644
--- a/src/google/protobuf/unittest_proto3_arena.proto
+++ b/src/google/protobuf/unittest_proto3_arena.proto
@@ -197,6 +197,7 @@ enum ForeignEnum {
   FOREIGN_FOO = 4;
   FOREIGN_BAR = 5;
   FOREIGN_BAZ = 6;
+  FOREIGN_LARGE = 123456;  // Large enough to escape the Boxed Integer cache.
 }
 
 // TestEmptyMessage is used to test behavior of unknown fields.
diff --git a/src/google/protobuf/wire_format.cc b/src/google/protobuf/wire_format.cc
index 72e13c4ba7..99db63f76e 100644
--- a/src/google/protobuf/wire_format.cc
+++ b/src/google/protobuf/wire_format.cc
@@ -766,6 +766,44 @@ struct WireFormat::MessageSetParser {
   const Reflection* reflection;
 };
 
+static const char* HandleMessage(Message* msg, const char* ptr,
+                                 internal::ParseContext* ctx, uint64_t tag,
+                                 const Reflection* reflection,
+                                 const FieldDescriptor* field) {
+  Message* sub_message;
+  if (field->is_repeated()) {
+    sub_message = reflection->AddMessage(msg, field, ctx->data().factory);
+  } else {
+    sub_message = reflection->MutableMessage(msg, field, ctx->data().factory);
+  }
+
+  if (WireFormatLite::GetTagWireType(tag) ==
+      WireFormatLite::WIRETYPE_START_GROUP) {
+    return ctx->ParseGroup(sub_message, ptr, tag);
+  } else {
+    ABSL_DCHECK(WireFormatLite::GetTagWireType(tag) ==
+                WireFormatLite::WIRETYPE_LENGTH_DELIMITED);
+  }
+
+  ptr = ctx->ParseMessage(sub_message, ptr);
+
+  // For map entries, if the value is an unknown enum we have to push it
+  // into the unknown field set and remove it from the list.
+  if (ptr != nullptr && field->is_map()) {
+    auto* value_field = field->message_type()->map_value();
+    auto* enum_type = value_field->enum_type();
+    if (enum_type != nullptr &&
+        !internal::cpp::HasPreservingUnknownEnumSemantics(value_field) &&
+        enum_type->FindValueByNumber(sub_message->GetReflection()->GetEnumValue(
+            *sub_message, value_field)) == nullptr) {
+      reflection->MutableUnknownFields(msg)->AddLengthDelimited(
+          field->number(), sub_message->SerializeAsString());
+      reflection->RemoveLast(msg, field);
+    }
+  }
+  return ptr;
+}
+
 const char* WireFormat::_InternalParse(Message* msg, const char* ptr,
                                        internal::ParseContext* ctx) {
   const Descriptor* descriptor = msg->GetDescriptor();
@@ -995,46 +1033,9 @@ const char* WireFormat::_InternalParseAndMergeField(
       return ptr;
     }
 
-    case FieldDescriptor::TYPE_GROUP: {
-      Message* sub_message;
-      if (field->is_repeated()) {
-        sub_message = reflection->AddMessage(msg, field, ctx->data().factory);
-      } else {
-        sub_message =
-            reflection->MutableMessage(msg, field, ctx->data().factory);
-      }
-
-      return ctx->ParseGroup(sub_message, ptr, tag);
-    }
-
-    case FieldDescriptor::TYPE_MESSAGE: {
-      Message* sub_message;
-      if (field->is_repeated()) {
-        sub_message = reflection->AddMessage(msg, field, ctx->data().factory);
-      } else {
-        sub_message =
-            reflection->MutableMessage(msg, field, ctx->data().factory);
-      }
-      ptr = ctx->ParseMessage(sub_message, ptr);
-
-      // For map entries, if the value is an unknown enum we have to push it
-      // into the unknown field set and remove it from the list.
-      if (ptr != nullptr && field->is_map()) {
-        auto* value_field = field->message_type()->map_value();
-        auto* enum_type = value_field->enum_type();
-        if (enum_type != nullptr &&
-            !internal::cpp::HasPreservingUnknownEnumSemantics(value_field) &&
-            enum_type->FindValueByNumber(
-                sub_message->GetReflection()->GetEnumValue(
-                    *sub_message, value_field)) == nullptr) {
-          reflection->MutableUnknownFields(msg)->AddLengthDelimited(
-              field->number(), sub_message->SerializeAsString());
-          reflection->RemoveLast(msg, field);
-        }
-      }
-
-      return ptr;
-    }
+    case FieldDescriptor::TYPE_MESSAGE:
+    case FieldDescriptor::TYPE_GROUP:
+      return HandleMessage(msg, ptr, ctx, tag, reflection, field);
   }
 
   // GCC 8 complains about control reaching end of non-void function here.
diff --git a/src/google/protobuf/wrappers.pb.cc b/src/google/protobuf/wrappers.pb.cc
index ee019eacfe..bae35ba17f 100644
--- a/src/google/protobuf/wrappers.pb.cc
+++ b/src/google/protobuf/wrappers.pb.cc
@@ -457,12 +457,7 @@ PROTOBUF_NOINLINE void DoubleValue::Clear() {
   (void)cached_has_bits;
 
   // double value = 1;
-  static_assert(sizeof(::uint64_t) == sizeof(double),
-                "Code assumes ::uint64_t and double are the same size.");
-  double tmp_value = this->_internal_value();
-  ::uint64_t raw_value;
-  memcpy(&raw_value, &tmp_value, sizeof(tmp_value));
-  if (raw_value != 0) {
+  if (::absl::bit_cast<::uint64_t>(this->_internal_value()) != 0) {
     target = stream->EnsureSpace(target);
     target = ::_pbi::WireFormatLite::WriteDoubleToArray(
         1, this->_internal_value(), target);
@@ -478,23 +473,19 @@ PROTOBUF_NOINLINE void DoubleValue::Clear() {
 }
 
 ::size_t DoubleValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.DoubleValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.DoubleValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // double value = 1;
-  static_assert(sizeof(::uint64_t) == sizeof(double),
-                "Code assumes ::uint64_t and double are the same size.");
-  double tmp_value = this->_internal_value();
-  ::uint64_t raw_value;
-  memcpy(&raw_value, &tmp_value, sizeof(tmp_value));
-  if (raw_value != 0) {
-    total_size += 9;
+   {
+    // double value = 1;
+    if (::absl::bit_cast<::uint64_t>(this->_internal_value()) != 0) {
+      total_size += 9;
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -507,12 +498,7 @@ void DoubleValue::MergeImpl(::google::protobuf::MessageLite& to_msg, const ::goo
   ::uint32_t cached_has_bits = 0;
   (void) cached_has_bits;
 
-  static_assert(sizeof(::uint64_t) == sizeof(double),
-                "Code assumes ::uint64_t and double are the same size.");
-  double tmp_value = from._internal_value();
-  ::uint64_t raw_value;
-  memcpy(&raw_value, &tmp_value, sizeof(tmp_value));
-  if (raw_value != 0) {
+  if (::absl::bit_cast<::uint64_t>(from._internal_value()) != 0) {
     _this->_impl_.value_ = from._impl_.value_;
   }
   _this->_internal_metadata_.MergeFrom<::google::protobuf::UnknownFieldSet>(from._internal_metadata_);
@@ -643,12 +629,7 @@ PROTOBUF_NOINLINE void FloatValue::Clear() {
   (void)cached_has_bits;
 
   // float value = 1;
-  static_assert(sizeof(::uint32_t) == sizeof(float),
-                "Code assumes ::uint32_t and float are the same size.");
-  float tmp_value = this->_internal_value();
-  ::uint32_t raw_value;
-  memcpy(&raw_value, &tmp_value, sizeof(tmp_value));
-  if (raw_value != 0) {
+  if (::absl::bit_cast<::uint32_t>(this->_internal_value()) != 0) {
     target = stream->EnsureSpace(target);
     target = ::_pbi::WireFormatLite::WriteFloatToArray(
         1, this->_internal_value(), target);
@@ -664,23 +645,19 @@ PROTOBUF_NOINLINE void FloatValue::Clear() {
 }
 
 ::size_t FloatValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.FloatValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.FloatValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // float value = 1;
-  static_assert(sizeof(::uint32_t) == sizeof(float),
-                "Code assumes ::uint32_t and float are the same size.");
-  float tmp_value = this->_internal_value();
-  ::uint32_t raw_value;
-  memcpy(&raw_value, &tmp_value, sizeof(tmp_value));
-  if (raw_value != 0) {
-    total_size += 5;
+   {
+    // float value = 1;
+    if (::absl::bit_cast<::uint32_t>(this->_internal_value()) != 0) {
+      total_size += 5;
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -693,12 +670,7 @@ void FloatValue::MergeImpl(::google::protobuf::MessageLite& to_msg, const ::goog
   ::uint32_t cached_has_bits = 0;
   (void) cached_has_bits;
 
-  static_assert(sizeof(::uint32_t) == sizeof(float),
-                "Code assumes ::uint32_t and float are the same size.");
-  float tmp_value = from._internal_value();
-  ::uint32_t raw_value;
-  memcpy(&raw_value, &tmp_value, sizeof(tmp_value));
-  if (raw_value != 0) {
+  if (::absl::bit_cast<::uint32_t>(from._internal_value()) != 0) {
     _this->_impl_.value_ = from._impl_.value_;
   }
   _this->_internal_metadata_.MergeFrom<::google::protobuf::UnknownFieldSet>(from._internal_metadata_);
@@ -845,19 +817,20 @@ PROTOBUF_NOINLINE void Int64Value::Clear() {
 }
 
 ::size_t Int64Value::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Int64Value)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Int64Value)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // int64 value = 1;
-  if (this->_internal_value() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
-        this->_internal_value());
+   {
+    // int64 value = 1;
+    if (this->_internal_value() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int64SizePlusOne(
+          this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1017,19 +990,20 @@ PROTOBUF_NOINLINE void UInt64Value::Clear() {
 }
 
 ::size_t UInt64Value::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.UInt64Value)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.UInt64Value)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // uint64 value = 1;
-  if (this->_internal_value() != 0) {
-    total_size += ::_pbi::WireFormatLite::UInt64SizePlusOne(
-        this->_internal_value());
+   {
+    // uint64 value = 1;
+    if (this->_internal_value() != 0) {
+      total_size += ::_pbi::WireFormatLite::UInt64SizePlusOne(
+          this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1189,19 +1163,20 @@ PROTOBUF_NOINLINE void Int32Value::Clear() {
 }
 
 ::size_t Int32Value::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.Int32Value)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.Int32Value)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // int32 value = 1;
-  if (this->_internal_value() != 0) {
-    total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
-        this->_internal_value());
+   {
+    // int32 value = 1;
+    if (this->_internal_value() != 0) {
+      total_size += ::_pbi::WireFormatLite::Int32SizePlusOne(
+          this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1361,19 +1336,20 @@ PROTOBUF_NOINLINE void UInt32Value::Clear() {
 }
 
 ::size_t UInt32Value::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.UInt32Value)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.UInt32Value)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // uint32 value = 1;
-  if (this->_internal_value() != 0) {
-    total_size += ::_pbi::WireFormatLite::UInt32SizePlusOne(
-        this->_internal_value());
+   {
+    // uint32 value = 1;
+    if (this->_internal_value() != 0) {
+      total_size += ::_pbi::WireFormatLite::UInt32SizePlusOne(
+          this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1533,18 +1509,19 @@ PROTOBUF_NOINLINE void BoolValue::Clear() {
 }
 
 ::size_t BoolValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.BoolValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.BoolValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // bool value = 1;
-  if (this->_internal_value() != 0) {
-    total_size += 2;
+   {
+    // bool value = 1;
+    if (this->_internal_value() != 0) {
+      total_size += 2;
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1722,19 +1699,20 @@ PROTOBUF_NOINLINE void StringValue::Clear() {
 }
 
 ::size_t StringValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.StringValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.StringValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // string value = 1;
-  if (!this->_internal_value().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
-                                    this->_internal_value());
+   {
+    // string value = 1;
+    if (!this->_internal_value().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::StringSize(
+                                      this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
@@ -1909,19 +1887,20 @@ PROTOBUF_NOINLINE void BytesValue::Clear() {
 }
 
 ::size_t BytesValue::ByteSizeLong() const {
-// @@protoc_insertion_point(message_byte_size_start:google.protobuf.BytesValue)
+  // @@protoc_insertion_point(message_byte_size_start:google.protobuf.BytesValue)
   ::size_t total_size = 0;
 
   ::uint32_t cached_has_bits = 0;
   // Prevent compiler warnings about cached_has_bits being unused
-  (void) cached_has_bits;
+  (void)cached_has_bits;
 
-  // bytes value = 1;
-  if (!this->_internal_value().empty()) {
-    total_size += 1 + ::google::protobuf::internal::WireFormatLite::BytesSize(
-                                    this->_internal_value());
+   {
+    // bytes value = 1;
+    if (!this->_internal_value().empty()) {
+      total_size += 1 + ::google::protobuf::internal::WireFormatLite::BytesSize(
+                                      this->_internal_value());
+    }
   }
-
   return MaybeComputeUnknownFieldsSize(total_size, &_impl_._cached_size_);
 }
 
diff --git a/third_party/utf8_range/CMakeLists.txt b/third_party/utf8_range/CMakeLists.txt
index 8d7a6e15c6..4276b97290 100644
--- a/third_party/utf8_range/CMakeLists.txt
+++ b/third_party/utf8_range/CMakeLists.txt
@@ -11,13 +11,13 @@ option (utf8_range_ENABLE_INSTALL "Configure installation" ON)
 
 ##
 # Create the lightweight C library
-add_library (utf8_range STATIC
+add_library (utf8_range
   utf8_range.c
 )
 
 ##
 # A heavier-weight C++ wrapper that supports Abseil.
-add_library (utf8_validity STATIC utf8_validity.cc utf8_range.c)
+add_library (utf8_validity utf8_validity.cc utf8_range.c)
 
 # Load Abseil dependency.
 if (NOT TARGET absl::strings)
diff --git a/upb/README.md b/upb/README.md
index a0c6849eca..61eaddd554 100644
--- a/upb/README.md
+++ b/upb/README.md
@@ -8,7 +8,7 @@ in C.
 upb is the core runtime for protobuf languages extensions in
 [Ruby](https://github.com/protocolbuffers/protobuf/tree/main/ruby),
 [PHP](https://github.com/protocolbuffers/protobuf/tree/main/php), and
-[Python](https://github.com/protocolbuffers/protobuf/tree/main/upb/python).
+[Python](https://github.com/protocolbuffers/protobuf/tree/main/python).
 
 While upb offers a C API, the C API & ABI **are not stable**. For this reason,
 upb is not generally offered as a C library for direct consumption, and there
diff --git a/upb/cmake/google/protobuf/descriptor.upb.h b/upb/cmake/google/protobuf/descriptor.upb.h
index fdedcbbab7..bdb3b5f6e0 100644
--- a/upb/cmake/google/protobuf/descriptor.upb.h
+++ b/upb/cmake/google/protobuf/descriptor.upb.h
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
diff --git a/upb/cmake/google/protobuf/descriptor.upb_minitable.c b/upb/cmake/google/protobuf/descriptor.upb_minitable.c
index eba76e82eb..80d12682e5 100644
--- a/upb/cmake/google/protobuf/descriptor.upb_minitable.c
+++ b/upb/cmake/google/protobuf/descriptor.upb_minitable.c
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #include <stddef.h>
 #include "upb/generated_code_support.h"
diff --git a/upb/cmake/google/protobuf/descriptor.upb_minitable.h b/upb/cmake/google/protobuf/descriptor.upb_minitable.h
index f48a64df65..4fc7176c59 100644
--- a/upb/cmake/google/protobuf/descriptor.upb_minitable.h
+++ b/upb/cmake/google/protobuf/descriptor.upb_minitable.h
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
diff --git a/upb/json/decode.c b/upb/json/decode.c
index 46a122efe3..c578451836 100644
--- a/upb/json/decode.c
+++ b/upb/json/decode.c
@@ -861,6 +861,7 @@ static upb_MessageValue jsondec_bool(jsondec* d, const upb_FieldDef* f) {
 /* Composite types (array/message/map) ****************************************/
 
 static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Array* arr = upb_Message_Mutable(msg, f, d->arena).array;
 
   jsondec_arrstart(d);
@@ -874,6 +875,7 @@ static void jsondec_array(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 }
 
 static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Map* map = upb_Message_Mutable(msg, f, d->arena).map;
   const upb_MessageDef* entry = upb_FieldDef_MessageSubDef(f);
   const upb_FieldDef* key_f = upb_MessageDef_FindFieldByNumber(entry, 1);
@@ -895,6 +897,7 @@ static void jsondec_map(jsondec* d, upb_Message* msg, const upb_FieldDef* f) {
 
 static void jsondec_tomsg(jsondec* d, upb_Message* msg,
                           const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (upb_MessageDef_WellKnownType(m) == kUpb_WellKnown_Unspecified) {
     jsondec_object(d, msg, m);
   } else {
@@ -915,6 +918,7 @@ static upb_MessageValue jsondec_msg(jsondec* d, const upb_FieldDef* f) {
 
 static void jsondec_field(jsondec* d, upb_Message* msg,
                           const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView name;
   const upb_FieldDef* f;
   const upb_FieldDef* preserved;
@@ -980,6 +984,7 @@ static void jsondec_field(jsondec* d, upb_Message* msg,
 
 static void jsondec_object(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   jsondec_objstart(d);
   while (jsondec_objnext(d)) {
     jsondec_field(d, msg, m);
@@ -1080,6 +1085,7 @@ static int64_t jsondec_unixtime(int y, int m, int d, int h, int min, int s) {
 
 static void jsondec_timestamp(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue seconds;
   upb_MessageValue nanos;
   upb_StringView str = jsondec_string(d);
@@ -1145,6 +1151,7 @@ malformed:
 
 static void jsondec_duration(jsondec* d, upb_Message* msg,
                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue seconds;
   upb_MessageValue nanos;
   upb_StringView str = jsondec_string(d);
@@ -1177,6 +1184,7 @@ static void jsondec_duration(jsondec* d, upb_Message* msg,
 
 static void jsondec_listvalue(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* values_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* value_m = upb_FieldDef_MessageSubDef(values_f);
   const upb_MiniTable* value_layout = upb_MessageDef_MiniTable(value_m);
@@ -1195,6 +1203,7 @@ static void jsondec_listvalue(jsondec* d, upb_Message* msg,
 
 static void jsondec_struct(jsondec* d, upb_Message* msg,
                            const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* fields_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* entry_m = upb_FieldDef_MessageSubDef(fields_f);
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(entry_m, 2);
@@ -1217,6 +1226,7 @@ static void jsondec_struct(jsondec* d, upb_Message* msg,
 
 static void jsondec_wellknownvalue(jsondec* d, upb_Message* msg,
                                    const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_MessageValue val;
   const upb_FieldDef* f;
   upb_Message* submsg;
@@ -1305,6 +1315,7 @@ static upb_StringView jsondec_mask(jsondec* d, const char* buf,
 
 static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   /* repeated string paths = 1; */
   const upb_FieldDef* paths_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_Array* arr = upb_Message_Mutable(msg, paths_f, d->arena).array;
@@ -1328,6 +1339,7 @@ static void jsondec_fieldmask(jsondec* d, upb_Message* msg,
 
 static void jsondec_anyfield(jsondec* d, upb_Message* msg,
                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (upb_MessageDef_WellKnownType(m) == kUpb_WellKnown_Unspecified) {
     /* For regular types: {"@type": "[user type]", "f1": <V1>, "f2": <V2>}
      * where f1, f2, etc. are the normal fields of this type. */
@@ -1346,6 +1358,7 @@ static void jsondec_anyfield(jsondec* d, upb_Message* msg,
 
 static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
                                              const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* type_url_f = upb_MessageDef_FindFieldByNumber(m, 1);
   const upb_MessageDef* type_m;
   upb_StringView type_url = jsondec_string(d);
@@ -1375,6 +1388,7 @@ static const upb_MessageDef* jsondec_typeurl(jsondec* d, upb_Message* msg,
 }
 
 static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   /* string type_url = 1;
    * bytes value = 2; */
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 2);
@@ -1443,6 +1457,7 @@ static void jsondec_any(jsondec* d, upb_Message* msg, const upb_MessageDef* m) {
 
 static void jsondec_wrapper(jsondec* d, upb_Message* msg,
                             const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_FieldDef* value_f = upb_MessageDef_FindFieldByNumber(m, 1);
   upb_JsonMessageValue val = jsondec_value(d, value_f);
   UPB_ASSUME(val.ignore == false);  // Wrapper cannot be an enum.
@@ -1451,6 +1466,7 @@ static void jsondec_wrapper(jsondec* d, upb_Message* msg,
 
 static void jsondec_wellknown(jsondec* d, upb_Message* msg,
                               const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   switch (upb_MessageDef_WellKnownType(m)) {
     case kUpb_WellKnown_Any:
       jsondec_any(d, msg, m);
@@ -1491,6 +1507,7 @@ static void jsondec_wellknown(jsondec* d, upb_Message* msg,
 
 static bool upb_JsonDecoder_Decode(jsondec* const d, upb_Message* const msg,
                                    const upb_MessageDef* const m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   if (UPB_SETJMP(d->err)) return false;
 
   jsondec_tomsg(d, msg, m);
diff --git a/upb/mem/arena.hpp b/upb/mem/arena.hpp
index e552ceb167..420adfa463 100644
--- a/upb/mem/arena.hpp
+++ b/upb/mem/arena.hpp
@@ -26,7 +26,11 @@ class Arena {
 
   upb_Arena* ptr() const { return ptr_.get(); }
 
-  void Fuse(Arena& other) { upb_Arena_Fuse(ptr(), other.ptr()); }
+  // Fuses the arenas together.
+  // This operation can only be performed on arenas with no initial blocks. Will
+  // return false if the fuse failed due to either arena having an initial
+  // block.
+  bool Fuse(Arena& other) { return upb_Arena_Fuse(ptr(), other.ptr()); }
 
  protected:
   std::unique_ptr<upb_Arena, decltype(&upb_Arena_Free)> ptr_;
diff --git a/upb/message/accessors.c b/upb/message/accessors.c
index a3184a5a21..de142d90d4 100644
--- a/upb/message/accessors.c
+++ b/upb/message/accessors.c
@@ -24,10 +24,8 @@ bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* m,
                              const upb_MiniTableField* f,
                              upb_Message* map_entry_message, upb_Arena* arena) {
   UPB_ASSERT(!upb_Message_IsFrozen(map_entry_message));
-
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_mini_table = upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  const upb_MiniTable* map_entry_mini_table =
+      upb_MiniTable_MapEntrySubMessage(m, f);
   UPB_ASSERT(map_entry_mini_table);
   const upb_MiniTableField* map_entry_key_field =
       upb_MiniTable_MapKey(map_entry_mini_table);
diff --git a/upb/message/accessors.h b/upb/message/accessors.h
index 59ec925d79..9e9b54b127 100644
--- a/upb/message/accessors.h
+++ b/upb/message/accessors.h
@@ -8,24 +8,17 @@
 #ifndef UPB_MESSAGE_ACCESSORS_H_
 #define UPB_MESSAGE_ACCESSORS_H_
 
-#include <stddef.h>
-#include <stdint.h>
-#include <string.h>
-
-#include "upb/base/descriptor_constants.h"
 #include "upb/base/string_view.h"
 #include "upb/mem/arena.h"
 #include "upb/message/array.h"
 #include "upb/message/internal/accessors.h"
-#include "upb/message/internal/array.h"
-#include "upb/message/internal/map.h"
-#include "upb/message/internal/message.h"
-#include "upb/message/internal/tagged_ptr.h"
 #include "upb/message/map.h"
+#include "upb/message/message.h"
 #include "upb/message/tagged_ptr.h"
 #include "upb/message/value.h"
-#include "upb/mini_table/enum.h"
-#include "upb/mini_table/sub.h"
+#include "upb/mini_table/extension.h"
+#include "upb/mini_table/field.h"
+#include "upb/mini_table/message.h"
 
 // Must be last.
 #include "upb/port/def.inc"
@@ -48,419 +41,211 @@ UPB_API_INLINE void upb_Message_ClearBaseField(upb_Message* msg,
 UPB_API_INLINE void upb_Message_ClearExtension(upb_Message* msg,
                                                const upb_MiniTableExtension* e);
 
+UPB_API_INLINE void upb_Message_ClearOneof(upb_Message* msg,
+                                           const upb_MiniTable* m,
+                                           const upb_MiniTableField* f);
+
 UPB_API_INLINE bool upb_Message_HasBaseField(const upb_Message* msg,
                                              const upb_MiniTableField* f);
 
 UPB_API_INLINE bool upb_Message_HasExtension(const upb_Message* msg,
                                              const upb_MiniTableExtension* e);
 
-UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
-                                             const upb_MiniTableField* f,
-                                             const void* val);
+UPB_API_INLINE upb_MessageValue
+upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* f,
+                     upb_MessageValue default_val);
 
-UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
-                                             const upb_MiniTableExtension* e,
-                                             const void* val, upb_Arena* a);
+UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
+    const upb_Message* msg, const upb_MiniTableField* field,
+    upb_Message* default_val);
 
-UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
-    const upb_Message* message, const upb_MiniTableField* oneof_field) {
-  UPB_ASSUME(upb_MiniTableField_IsInOneof(oneof_field));
-  return UPB_PRIVATE(_upb_Message_GetOneofCase)(message, oneof_field);
-}
-
-// NOTE: The default_val is only used for fields that support presence.
-// For repeated/map fields, the resulting upb_Array*/upb_Map* can be NULL if a
-// upb_Array/upb_Map has not been allocated yet. Array/map fields do not have
-// presence, so this is semantically identical to a pointer to an empty
-// array/map, and must be treated the same for all semantic purposes.
-UPB_INLINE upb_MessageValue
-upb_Message_GetField(const upb_Message* msg, const upb_MiniTableField* field,
-                     upb_MessageValue default_val) {
-  upb_MessageValue ret;
-  if (upb_MiniTableField_IsExtension(field)) {
-    _upb_Message_GetExtensionField(msg, (upb_MiniTableExtension*)field,
-                                   &default_val, &ret);
-  } else {
-    _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  }
-  return ret;
-}
-
-// Sets the value of the given field in the given msg. The return value is true
-// if the operation completed successfully, or false if memory allocation
-// failed.
-UPB_INLINE bool UPB_PRIVATE(_upb_Message_SetField)(
-    upb_Message* msg, const upb_MiniTableField* field, upb_MessageValue val,
-    upb_Arena* a) {
-  if (upb_MiniTableField_IsExtension(field)) {
-    const upb_MiniTableExtension* ext = (const upb_MiniTableExtension*)field;
-    return upb_Message_SetExtension(msg, ext, &val, a);
-  } else {
-    upb_Message_SetBaseField(msg, field, &val);
-    return true;
-  }
-}
+UPB_API_INLINE const upb_Array* upb_Message_GetArray(
+    const upb_Message* msg, const upb_MiniTableField* f);
 
 UPB_API_INLINE bool upb_Message_GetBool(const upb_Message* msg,
-                                        const upb_MiniTableField* field,
-                                        bool default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Bool);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_1Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue def;
-  def.bool_val = default_val;
-  return upb_Message_GetField(msg, field, def).bool_val;
-}
+                                        const upb_MiniTableField* f,
+                                        bool default_val);
 
-UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
-                                        const upb_MiniTableField* field,
-                                        bool value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Bool);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_1Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.bool_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
+                                            const upb_MiniTableField* field,
+                                            double default_val);
+
+UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          float default_val);
 
 UPB_API_INLINE int32_t upb_Message_GetInt32(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            int32_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int32 ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Enum);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-
-  upb_MessageValue def;
-  def.int32_val = default_val;
-  return upb_Message_GetField(msg, field, def).int32_val;
-}
+                                            const upb_MiniTableField* f,
+                                            int32_t default_val);
 
-UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         int32_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int32 ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Enum);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.int32_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int64_t default_val);
+
+UPB_API_INLINE const upb_Map* upb_Message_GetMap(const upb_Message* msg,
+                                                 const upb_MiniTableField* f);
+
+UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
+    const upb_Message* msg, const upb_MiniTableField* f);
+
+UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
+    upb_Message* msg, const upb_MiniTableField* f);
+
+UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(upb_Message* msg,
+                                                  const upb_MiniTableField* f);
+
+UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
+    upb_Message* msg, const upb_MiniTableField* f);
+
+UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
+    upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena);
+
+UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
+    upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena);
+
+UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
+    upb_Message* msg, const upb_MiniTable* mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena);
+
+UPB_API_INLINE upb_StringView
+upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
+                      upb_StringView default_val);
 
 UPB_API_INLINE uint32_t upb_Message_GetUInt32(const upb_Message* msg,
-                                              const upb_MiniTableField* field,
-                                              uint32_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt32);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-
-  upb_MessageValue def;
-  def.uint32_val = default_val;
-  return upb_Message_GetField(msg, field, def).uint32_val;
-}
+                                              const upb_MiniTableField* f,
+                                              uint32_t default_val);
 
-UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          uint32_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt32);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.uint32_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint64_t default_val);
 
 UPB_API_INLINE void upb_Message_SetClosedEnum(
     upb_Message* msg, const upb_MiniTable* msg_mini_table,
-    const upb_MiniTableField* field, int32_t value) {
-  UPB_ASSERT(upb_MiniTableField_IsClosedEnum(field));
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  UPB_ASSERT(upb_MiniTableEnum_CheckValue(
-      upb_MiniTable_GetSubEnumTable(msg_mini_table, field), value));
-  upb_Message_SetBaseField(msg, field, &value);
-}
+    const upb_MiniTableField* f, int32_t value);
 
-UPB_API_INLINE int64_t upb_Message_GetInt64(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            int64_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+// BaseField Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE void upb_Message_SetBaseField(upb_Message* msg,
+                                             const upb_MiniTableField* f,
+                                             const void* val);
 
-  upb_MessageValue def;
-  def.int64_val = default_val;
-  return upb_Message_GetField(msg, field, def).int64_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldBool(struct upb_Message* msg,
+                                                 const upb_MiniTableField* f,
+                                                 bool value);
 
-UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         int64_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Int64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.int64_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldDouble(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   double value);
 
-UPB_API_INLINE uint64_t upb_Message_GetUInt64(const upb_Message* msg,
-                                              const upb_MiniTableField* field,
-                                              uint64_t default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-
-  upb_MessageValue def;
-  def.uint64_val = default_val;
-  return upb_Message_GetField(msg, field, def).uint64_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldFloat(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  float value);
 
-UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          uint64_t value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_UInt64);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.uint64_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldInt32(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int32_t value);
 
-UPB_API_INLINE float upb_Message_GetFloat(const upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          float default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Float);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-
-  upb_MessageValue def;
-  def.float_val = default_val;
-  return upb_Message_GetField(msg, field, def).float_val;
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldInt64(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int64_t value);
 
-UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
-                                         const upb_MiniTableField* field,
-                                         float value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Float);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_4Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.float_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE void upb_Message_SetBaseFieldString(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_StringView value);
 
-UPB_API_INLINE double upb_Message_GetDouble(const upb_Message* msg,
-                                            const upb_MiniTableField* field,
-                                            double default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Double);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt32(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint32_t value);
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt64(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint64_t value);
 
-  upb_MessageValue def;
-  def.double_val = default_val;
-  return upb_Message_GetField(msg, field, def).double_val;
-}
+// Extension Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetExtension(upb_Message* msg,
+                                             const upb_MiniTableExtension* e,
+                                             const void* value, upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionBool(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, bool value,
+    upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionDouble(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, double value,
+    upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionFloat(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, float value,
+    upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int32_t value,
+    upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int64_t value,
+    upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionString(
+    struct upb_Message* msg, const upb_MiniTableExtension* e,
+    upb_StringView value, upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint32_t value,
+    upb_Arena* a);
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint64_t value,
+    upb_Arena* a);
+
+// Universal Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetBool(upb_Message* msg,
+                                        const upb_MiniTableField* f, bool value,
+                                        upb_Arena* a);
 
 UPB_API_INLINE bool upb_Message_SetDouble(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          double value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Double);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_8Byte);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.double_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+                                          const upb_MiniTableField* f,
+                                          double value, upb_Arena* a);
 
-UPB_API_INLINE upb_StringView
-upb_Message_GetString(const upb_Message* msg, const upb_MiniTableField* field,
-                      upb_StringView default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_String ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Bytes);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_StringView);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-
-  upb_MessageValue def;
-  def.str_val = default_val;
-  return upb_Message_GetField(msg, field, def).str_val;
-}
-
-// Sets the value of a `string` or `bytes` field. The bytes of the value are not
-// copied, so it is the caller's responsibility to ensure that they remain valid
-// for the lifetime of `msg`. That might be done by copying them into the given
-// arena, or by fusing that arena with the arena the bytes live in, for example.
-UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
-                                          const upb_MiniTableField* field,
-                                          upb_StringView value, upb_Arena* a) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_String ||
-             upb_MiniTableField_CType(field) == kUpb_CType_Bytes);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             kUpb_FieldRep_StringView);
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_MessageValue val;
-  val.str_val = value;
-  return UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, a);
-}
+UPB_API_INLINE bool upb_Message_SetFloat(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         float value, upb_Arena* a);
 
-UPB_API_INLINE upb_TaggedMessagePtr upb_Message_GetTaggedMessagePtr(
-    const upb_Message* msg, const upb_MiniTableField* field,
-    upb_Message* default_val) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  upb_TaggedMessagePtr tagged;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
-  return tagged;
-}
+UPB_API_INLINE bool upb_Message_SetInt32(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int32_t value, upb_Arena* a);
 
-UPB_API_INLINE const upb_Message* upb_Message_GetMessage(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  upb_TaggedMessagePtr tagged =
-      upb_Message_GetTaggedMessagePtr(msg, field, NULL);
-  return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
-}
+UPB_API_INLINE bool upb_Message_SetInt64(upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int64_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Message* upb_Message_GetMutableMessage(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  return (upb_Message*)upb_Message_GetMessage(msg, field);
-}
-
-// For internal use only; users cannot set tagged messages because only the
-// parser and the message copier are allowed to directly create an empty
-// message.
-UPB_API_INLINE void _upb_Message_SetTaggedMessagePtr(
-    upb_Message* msg, const upb_MiniTable* mini_table,
-    const upb_MiniTableField* field, upb_TaggedMessagePtr sub_message) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
-             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
-  UPB_ASSUME(upb_MiniTableField_IsScalar(field));
-  UPB_ASSERT(upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]));
-  upb_Message_SetBaseField(msg, field, &sub_message);
-}
-
-// Sets the value of a message-typed field. The `mini_table` and `field`
-// parameters belong to `msg`, not `sub_message`. The mini_tables of `msg` and
-// `sub_message` must have been linked for this to work correctly.
 UPB_API_INLINE void upb_Message_SetMessage(upb_Message* msg,
-                                           const upb_MiniTable* mini_table,
-                                           const upb_MiniTableField* field,
-                                           upb_Message* sub_message) {
-  _upb_Message_SetTaggedMessagePtr(
-      msg, mini_table, field,
-      UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(sub_message, false));
-}
+                                           const upb_MiniTableField* f,
+                                           upb_Message* value);
 
-UPB_API_INLINE upb_Message* upb_Message_GetOrCreateMutableMessage(
-    upb_Message* msg, const upb_MiniTable* mini_table,
-    const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSERT(arena);
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  upb_Message* sub_message =
-      *UPB_PTR_AT(msg, field->UPB_ONLYBITS(offset), upb_Message*);
-  if (!sub_message) {
-    const upb_MiniTable* sub_mini_table = upb_MiniTableSub_Message(
-        mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]);
-    UPB_ASSERT(sub_mini_table);
-    sub_message = _upb_Message_New(sub_mini_table, arena);
-    *UPB_PTR_AT(msg, field->UPB_ONLYBITS(offset), upb_Message*) = sub_message;
-    UPB_PRIVATE(_upb_Message_SetPresence)(msg, field);
-  }
-  return sub_message;
-}
+UPB_API_INLINE bool upb_Message_SetString(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          upb_StringView value, upb_Arena* a);
 
-UPB_API_INLINE const upb_Array* upb_Message_GetArray(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* ret;
-  const upb_Array* default_val = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  return ret;
-}
+UPB_API_INLINE bool upb_Message_SetUInt32(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint32_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  return (upb_Array*)upb_Message_GetArray(msg, field);
-}
+UPB_API_INLINE bool upb_Message_SetUInt64(upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint64_t value, upb_Arena* a);
 
-UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
-    upb_Message* msg, const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSERT(arena);
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* array = upb_Message_GetMutableArray(msg, field);
-  if (!array) {
-    array = UPB_PRIVATE(_upb_Array_New)(
-        arena, 4, UPB_PRIVATE(_upb_MiniTableField_ElemSizeLg2)(field));
-    // Check again due to: https://godbolt.org/z/7WfaoKG1r
-    UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-    upb_MessageValue val;
-    val.array_val = array;
-    UPB_PRIVATE(_upb_Message_SetField)(msg, field, val, arena);
-  }
-  return array;
-}
+////////////////////////////////////////////////////////////////////////////////
 
 UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
-    upb_Message* msg, const upb_MiniTableField* field, size_t size,
-    upb_Arena* arena) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
-  upb_Array* arr = upb_Message_GetOrCreateMutableArray(msg, field, arena);
-  if (!arr || !UPB_PRIVATE(_upb_Array_ResizeUninitialized)(arr, size, arena)) {
-    return NULL;
-  }
-  return upb_Array_MutableDataPtr(arr);
-}
-
-UPB_API_INLINE const upb_Map* upb_Message_GetMap(
-    const upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-  _upb_Message_AssertMapIsUntagged(msg, field);
-  upb_Map* ret;
-  const upb_Map* default_val = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
-  return ret;
-}
-
-UPB_API_INLINE upb_Map* upb_Message_GetMutableMap(
-    upb_Message* msg, const upb_MiniTableField* field) {
-  return (upb_Map*)upb_Message_GetMap(msg, field);
-}
+    upb_Message* msg, const upb_MiniTableField* f, size_t size,
+    upb_Arena* arena);
 
-UPB_API_INLINE upb_Map* upb_Message_GetOrCreateMutableMap(
-    upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
-    const upb_MiniTableField* field, upb_Arena* arena) {
-  UPB_ASSUME(upb_MiniTableField_CType(field) == kUpb_CType_Message);
-  const upb_MiniTableField* map_entry_key_field =
-      &map_entry_mini_table->UPB_ONLYBITS(fields)[0];
-  const upb_MiniTableField* map_entry_value_field =
-      &map_entry_mini_table->UPB_ONLYBITS(fields)[1];
-  return _upb_Message_GetOrCreateMutableMap(
-      msg, field,
-      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_key_field)),
-      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_value_field)),
-      arena);
-}
+UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
+    const upb_Message* message, const upb_MiniTableField* oneof_field);
 
 // Updates a map entry given an entry message.
 bool upb_Message_SetMapEntry(upb_Map* map, const upb_MiniTable* mini_table,
diff --git a/upb/message/accessors_test.cc b/upb/message/accessors_test.cc
index 5b0dd3638c..76248578b3 100644
--- a/upb/message/accessors_test.cc
+++ b/upb/message/accessors_test.cc
@@ -179,8 +179,8 @@ TEST(GeneratedCode, ScalarsProto2) {
       0, protobuf_test_messages_proto2_TestAllTypesProto2_optional_int32(msg));
 
   EXPECT_EQ(0, upb_Message_GetInt32(UPB_UPCAST(msg), optional_int32_field, 0));
-  upb_Message_SetInt32(UPB_UPCAST(msg), optional_int32_field, kTestInt32,
-                       nullptr);
+  upb_Message_SetBaseFieldInt32(UPB_UPCAST(msg), optional_int32_field,
+                                kTestInt32);
   EXPECT_EQ(true,
             upb_Message_HasBaseField(UPB_UPCAST(msg), optional_int32_field));
   EXPECT_EQ(kTestInt32,
@@ -196,8 +196,8 @@ TEST(GeneratedCode, ScalarsProto2) {
       0, protobuf_test_messages_proto2_TestAllTypesProto2_optional_uint32(msg));
   EXPECT_EQ(0,
             upb_Message_GetUInt32(UPB_UPCAST(msg), optional_uint32_field, 0));
-  upb_Message_SetUInt32(UPB_UPCAST(msg), optional_uint32_field, kTestUInt32,
-                        nullptr);
+  upb_Message_SetBaseFieldUInt32(UPB_UPCAST(msg), optional_uint32_field,
+                                 kTestUInt32);
   EXPECT_EQ(kTestUInt32,
             upb_Message_GetUInt32(UPB_UPCAST(msg), optional_uint32_field, 0));
   EXPECT_EQ(
@@ -219,15 +219,15 @@ TEST(GeneratedCode, ScalarProto3) {
 
   EXPECT_EQ(
       0, protobuf_test_messages_proto3_TestAllTypesProto3_optional_int64(msg));
-  upb_Message_SetInt64(UPB_UPCAST(msg), optional_int64_field, -1, nullptr);
+  upb_Message_SetBaseFieldInt64(UPB_UPCAST(msg), optional_int64_field, -1);
   EXPECT_EQ(
       -1, protobuf_test_messages_proto3_TestAllTypesProto3_optional_int64(msg));
   EXPECT_EQ(-1, upb_Message_GetInt64(UPB_UPCAST(msg), optional_int64_field, 0));
 
   EXPECT_EQ(
       0, protobuf_test_messages_proto3_TestAllTypesProto3_optional_uint64(msg));
-  upb_Message_SetUInt64(UPB_UPCAST(msg), optional_uint64_field, kTestUInt64,
-                        nullptr);
+  upb_Message_SetBaseFieldUInt64(UPB_UPCAST(msg), optional_uint64_field,
+                                 kTestUInt64);
   EXPECT_EQ(
       kTestUInt64,
       protobuf_test_messages_proto3_TestAllTypesProto3_optional_uint64(msg));
@@ -265,8 +265,8 @@ TEST(GeneratedCode, Strings) {
       false,
       protobuf_test_messages_proto2_TestAllTypesProto2_has_optional_string(
           msg));
-  upb_Message_SetString(UPB_UPCAST(msg), optional_string_field,
-                        upb_StringView_FromString(kTestStr2), nullptr);
+  upb_Message_SetBaseFieldString(UPB_UPCAST(msg), optional_string_field,
+                                 upb_StringView_FromString(kTestStr2));
   EXPECT_EQ(true,
             upb_Message_HasBaseField(UPB_UPCAST(msg), optional_string_field));
   EXPECT_EQ(
@@ -327,12 +327,10 @@ TEST(GeneratedCode, SubMessage) {
   upb_Message* new_nested_message = UPB_UPCAST(
       protobuf_test_messages_proto2_TestAllTypesProto2_NestedMessage_new(
           arena));
-  upb_Message_SetInt32(new_nested_message, nested_message_a_field, 123,
-                       nullptr);
-  upb_Message_SetMessage(
-      UPB_UPCAST(msg),
-      &protobuf_0test_0messages__proto2__TestAllTypesProto2_msg_init,
-      optional_message_field, new_nested_message);
+  upb_Message_SetBaseFieldInt32(new_nested_message, nested_message_a_field,
+                                123);
+  upb_Message_SetMessage(UPB_UPCAST(msg), optional_message_field,
+                         new_nested_message);
 
   upb_Message* mutable_message = upb_Message_GetOrCreateMutableMessage(
       UPB_UPCAST(msg),
@@ -478,4 +476,28 @@ TEST(GeneratedCode, EnumClosedCheck) {
   upb_Arena_Free(arena);
 }
 
+TEST(GeneratedCode, OneofClear) {
+  upb_Arena* arena = upb_Arena_New();
+
+  protobuf_test_messages_proto2_TestAllTypesProto2* msg =
+      protobuf_test_messages_proto2_TestAllTypesProto2_new(arena);
+
+  const upb_MiniTable* table =
+      &protobuf_0test_0messages__proto2__TestAllTypesProto2_msg_init;
+
+  // oneof_uint32
+  const upb_MiniTableField* oneofField =
+      upb_MiniTable_FindFieldByNumber(table, 111);
+  EXPECT_TRUE(upb_MiniTableField_IsInOneof(oneofField));
+  protobuf_test_messages_proto2_TestAllTypesProto2_set_oneof_uint32(msg, 522);
+  EXPECT_TRUE(
+      protobuf_test_messages_proto2_TestAllTypesProto2_has_oneof_uint32(msg));
+
+  upb_Message_ClearOneof((upb_Message*)msg, table, oneofField);
+  EXPECT_FALSE(
+      protobuf_test_messages_proto2_TestAllTypesProto2_has_oneof_uint32(msg));
+
+  upb_Arena_Free(arena);
+}
+
 }  // namespace
diff --git a/upb/message/copy.c b/upb/message/copy.c
index 114b92e018..67e1b5b503 100644
--- a/upb/message/copy.c
+++ b/upb/message/copy.c
@@ -117,9 +117,9 @@ static upb_Map* upb_Message_Map_DeepClone(const upb_Map* map,
                                           const upb_MiniTableField* f,
                                           upb_Message* clone,
                                           upb_Arena* arena) {
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_table = upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  UPB_ASSERT(!upb_Message_IsFrozen(clone));
+  const upb_MiniTable* map_entry_table =
+      upb_MiniTable_MapEntrySubMessage(mini_table, f);
   UPB_ASSERT(map_entry_table);
 
   const upb_MiniTableField* key_field = upb_MiniTable_MapKey(map_entry_table);
@@ -161,6 +161,7 @@ static bool upb_Message_Array_DeepClone(const upb_Array* array,
                                         const upb_MiniTable* mini_table,
                                         const upb_MiniTableField* field,
                                         upb_Message* clone, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(clone));
   UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(field);
   upb_Array* cloned_array = upb_Array_DeepClone(
       array, upb_MiniTableField_CType(field),
@@ -186,6 +187,7 @@ static bool upb_Clone_ExtensionValue(
 upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
                                const upb_MiniTable* mini_table,
                                upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   upb_StringView empty_string = upb_StringView_FromDataAndSize(NULL, 0);
   // Only copy message area skipping upb_Message_Internal.
   memcpy(dst + 1, src + 1, mini_table->UPB_PRIVATE(size) - sizeof(upb_Message));
@@ -212,10 +214,10 @@ upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
             if (dst_sub_message == NULL) {
               return NULL;
             }
-            _upb_Message_SetTaggedMessagePtr(
-                dst, mini_table, field,
-                UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(dst_sub_message,
-                                                        is_empty));
+            UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
+            (dst, field,
+             UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(dst_sub_message,
+                                                     is_empty));
           }
         } break;
         case kUpb_CType_String:
@@ -292,6 +294,7 @@ upb_Message* _upb_Message_Copy(upb_Message* dst, const upb_Message* src,
 
 bool upb_Message_DeepCopy(upb_Message* dst, const upb_Message* src,
                           const upb_MiniTable* mini_table, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   upb_Message_Clear(dst, mini_table);
   return _upb_Message_Copy(dst, src, mini_table, arena) != NULL;
 }
@@ -308,6 +311,7 @@ upb_Message* upb_Message_DeepClone(const upb_Message* msg,
 // Performs a shallow copy. TODO: Extend to handle unknown fields.
 void upb_Message_ShallowCopy(upb_Message* dst, const upb_Message* src,
                              const upb_MiniTable* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(dst));
   memcpy(dst, src, m->UPB_PRIVATE(size));
 }
 
diff --git a/upb/message/copy_test.cc b/upb/message/copy_test.cc
index 8434258cb2..1bdb3a3099 100644
--- a/upb/message/copy_test.cc
+++ b/upb/message/copy_test.cc
@@ -108,10 +108,8 @@ TEST(GeneratedCode, DeepCloneMessageSubMessage) {
           source_arena);
   protobuf_test_messages_proto2_TestAllTypesProto2_NestedMessage_set_a(
       nested, kTestNestedInt32);
-  upb_Message_SetMessage(
-      UPB_UPCAST(msg),
-      &protobuf_0test_0messages__proto2__TestAllTypesProto2_msg_init,
-      nested_message_field, UPB_UPCAST(nested));
+  upb_Message_SetMessage(UPB_UPCAST(msg), nested_message_field,
+                         UPB_UPCAST(nested));
   upb_Arena* arena = upb_Arena_New();
   protobuf_test_messages_proto2_TestAllTypesProto2* clone =
       (protobuf_test_messages_proto2_TestAllTypesProto2*)upb_Message_DeepClone(
diff --git a/upb/message/internal/accessors.h b/upb/message/internal/accessors.h
index bfae12e601..6e5e43ec62 100644
--- a/upb/message/internal/accessors.h
+++ b/upb/message/internal/accessors.h
@@ -12,14 +12,18 @@
 #include <stdint.h>
 #include <string.h>
 
+#include "upb/base/descriptor_constants.h"
 #include "upb/base/internal/endian.h"
 #include "upb/base/string_view.h"
 #include "upb/mem/arena.h"
+#include "upb/message/internal/array.h"
 #include "upb/message/internal/extension.h"
 #include "upb/message/internal/map.h"
 #include "upb/message/internal/message.h"
 #include "upb/message/internal/tagged_ptr.h"
 #include "upb/message/internal/types.h"
+#include "upb/message/value.h"
+#include "upb/mini_table/enum.h"
 #include "upb/mini_table/extension.h"
 #include "upb/mini_table/field.h"
 #include "upb/mini_table/internal/field.h"
@@ -112,6 +116,12 @@ UPB_INLINE bool UPB_PRIVATE(_upb_Message_ClearOneofCase)(
   return true;
 }
 
+UPB_API_INLINE uint32_t upb_Message_WhichOneofFieldNumber(
+    const struct upb_Message* message, const upb_MiniTableField* oneof_field) {
+  UPB_ASSUME(upb_MiniTableField_IsInOneof(oneof_field));
+  return UPB_PRIVATE(_upb_Message_GetOneofCase)(message, oneof_field);
+}
+
 // LINT.ThenChange(GoogleInternalName2)
 
 // Returns false if the message is missing any of its required fields.
@@ -210,7 +220,6 @@ UPB_INLINE bool UPB_PRIVATE(_upb_MiniTableField_DataIsZero)(
 //                                       const upb_MiniTableField* field,
 //                                       bool value, upb_Arena* a) {
 //     UPB_ASSUME(field->UPB_PRIVATE(descriptortype) == kUpb_FieldType_Bool);
-//     UPB_ASSUME(upb_MiniTableField_IsScalar(field));
 //     UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(field) ==
 //                kUpb_FieldRep_1Byte);
 //     upb_Message_SetField(msg, field, &value, a);
@@ -271,6 +280,24 @@ UPB_INLINE void _upb_Message_GetExtensionField(
   }
 }
 
+// NOTE: The default_val is only used for fields that support presence.
+// For repeated/map fields, the resulting upb_Array*/upb_Map* can be NULL if a
+// upb_Array/upb_Map has not been allocated yet. Array/map fields do not have
+// presence, so this is semantically identical to a pointer to an empty
+// array/map, and must be treated the same for all semantic purposes.
+UPB_API_INLINE upb_MessageValue upb_Message_GetField(
+    const struct upb_Message* msg, const upb_MiniTableField* field,
+    upb_MessageValue default_val) {
+  upb_MessageValue ret;
+  if (upb_MiniTableField_IsExtension(field)) {
+    _upb_Message_GetExtensionField(msg, (upb_MiniTableExtension*)field,
+                                   &default_val, &ret);
+  } else {
+    _upb_Message_GetNonExtensionField(msg, field, &default_val, &ret);
+  }
+  return ret;
+}
+
 UPB_API_INLINE void upb_Message_SetBaseField(struct upb_Message* msg,
                                              const upb_MiniTableField* f,
                                              const void* val) {
@@ -294,6 +321,516 @@ UPB_API_INLINE bool upb_Message_SetExtension(struct upb_Message* msg,
   return true;
 }
 
+// Sets the value of the given field in the given msg. The return value is true
+// if the operation completed successfully, or false if memory allocation
+// failed.
+UPB_INLINE bool UPB_PRIVATE(_upb_Message_SetField)(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_MessageValue val,
+                                                   upb_Arena* a) {
+  if (upb_MiniTableField_IsExtension(f)) {
+    const upb_MiniTableExtension* ext = (const upb_MiniTableExtension*)f;
+    return upb_Message_SetExtension(msg, ext, &val, a);
+  } else {
+    upb_Message_SetBaseField(msg, f, &val);
+    return true;
+  }
+}
+
+UPB_API_INLINE const upb_Array* upb_Message_GetArray(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* ret;
+  const upb_Array* default_val = NULL;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &ret);
+  return ret;
+}
+
+UPB_API_INLINE bool upb_Message_GetBool(const struct upb_Message* msg,
+                                        const upb_MiniTableField* f,
+                                        bool default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Bool);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_1Byte);
+  upb_MessageValue def;
+  def.bool_val = default_val;
+  return upb_Message_GetField(msg, f, def).bool_val;
+}
+
+UPB_API_INLINE double upb_Message_GetDouble(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            double default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Double);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.double_val = default_val;
+  return upb_Message_GetField(msg, f, def).double_val;
+}
+
+UPB_API_INLINE float upb_Message_GetFloat(const struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          float default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Float);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.float_val = default_val;
+  return upb_Message_GetField(msg, f, def).float_val;
+}
+
+UPB_API_INLINE int32_t upb_Message_GetInt32(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int32_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int32 ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Enum);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.int32_val = default_val;
+  return upb_Message_GetField(msg, f, def).int32_val;
+}
+
+UPB_API_INLINE int64_t upb_Message_GetInt64(const struct upb_Message* msg,
+                                            const upb_MiniTableField* f,
+                                            int64_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.int64_val = default_val;
+  return upb_Message_GetField(msg, f, def).int64_val;
+}
+
+UPB_INLINE void UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(
+    const struct upb_Message* msg, const upb_MiniTableField* field) {
+  UPB_UNUSED(msg);
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+#ifndef NDEBUG
+  uintptr_t default_val = 0;
+  uintptr_t tagged;
+  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
+  UPB_ASSERT(!upb_TaggedMessagePtr_IsEmpty(tagged));
+#endif
+}
+
+UPB_API_INLINE const struct upb_Map* upb_Message_GetMap(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(f);
+  UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(msg, f);
+  struct upb_Map* ret;
+  const struct upb_Map* default_val = NULL;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &ret);
+  return ret;
+}
+
+UPB_API_INLINE uintptr_t upb_Message_GetTaggedMessagePtr(
+    const struct upb_Message* msg, const upb_MiniTableField* f,
+    struct upb_Message* default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  uintptr_t tagged;
+  _upb_Message_GetNonExtensionField(msg, f, &default_val, &tagged);
+  return tagged;
+}
+
+// For internal use only; users cannot set tagged messages because only the
+// parser and the message copier are allowed to directly create an empty
+// message.
+UPB_INLINE void UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)(
+    struct upb_Message* msg, const upb_MiniTableField* f,
+    uintptr_t sub_message) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             UPB_SIZE(kUpb_FieldRep_4Byte, kUpb_FieldRep_8Byte));
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  upb_Message_SetBaseField(msg, f, &sub_message);
+}
+
+UPB_API_INLINE const struct upb_Message* upb_Message_GetMessage(
+    const struct upb_Message* msg, const upb_MiniTableField* f) {
+  uintptr_t tagged = upb_Message_GetTaggedMessagePtr(msg, f, NULL);
+  return upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
+}
+
+UPB_API_INLINE upb_Array* upb_Message_GetMutableArray(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  return (upb_Array*)upb_Message_GetArray(msg, f);
+}
+
+UPB_API_INLINE struct upb_Map* upb_Message_GetMutableMap(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  return (struct upb_Map*)upb_Message_GetMap(msg, f);
+}
+
+UPB_API_INLINE struct upb_Message* upb_Message_GetMutableMessage(
+    struct upb_Message* msg, const upb_MiniTableField* f) {
+  return (struct upb_Message*)upb_Message_GetMessage(msg, f);
+}
+
+UPB_API_INLINE upb_Array* upb_Message_GetOrCreateMutableArray(
+    struct upb_Message* msg, const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSERT(arena);
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* array = upb_Message_GetMutableArray(msg, f);
+  if (!array) {
+    array = UPB_PRIVATE(_upb_Array_New)(
+        arena, 4, UPB_PRIVATE(_upb_MiniTableField_ElemSizeLg2)(f));
+    // Check again due to: https://godbolt.org/z/7WfaoKG1r
+    UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+    upb_MessageValue val;
+    val.array_val = array;
+    UPB_PRIVATE(_upb_Message_SetField)(msg, f, val, arena);
+  }
+  return array;
+}
+
+UPB_INLINE struct upb_Map* _upb_Message_GetOrCreateMutableMap(
+    struct upb_Message* msg, const upb_MiniTableField* field, size_t key_size,
+    size_t val_size, upb_Arena* arena) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+  UPB_PRIVATE(_upb_Message_AssertMapIsUntagged)(msg, field);
+  struct upb_Map* map = NULL;
+  struct upb_Map* default_map_value = NULL;
+  _upb_Message_GetNonExtensionField(msg, field, &default_map_value, &map);
+  if (!map) {
+    map = _upb_Map_New(arena, key_size, val_size);
+    // Check again due to: https://godbolt.org/z/7WfaoKG1r
+    UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
+    upb_Message_SetBaseField(msg, field, &map);
+  }
+  return map;
+}
+
+UPB_API_INLINE struct upb_Map* upb_Message_GetOrCreateMutableMap(
+    struct upb_Message* msg, const upb_MiniTable* map_entry_mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  const upb_MiniTableField* map_entry_key_field =
+      &map_entry_mini_table->UPB_ONLYBITS(fields)[0];
+  const upb_MiniTableField* map_entry_value_field =
+      &map_entry_mini_table->UPB_ONLYBITS(fields)[1];
+  return _upb_Message_GetOrCreateMutableMap(
+      msg, f, _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_key_field)),
+      _upb_Map_CTypeSize(upb_MiniTableField_CType(map_entry_value_field)),
+      arena);
+}
+
+UPB_API_INLINE struct upb_Message* upb_Message_GetOrCreateMutableMessage(
+    struct upb_Message* msg, const upb_MiniTable* mini_table,
+    const upb_MiniTableField* f, upb_Arena* arena) {
+  UPB_ASSERT(arena);
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  UPB_ASSUME(!upb_MiniTableField_IsExtension(f));
+  struct upb_Message* sub_message =
+      *UPB_PTR_AT(msg, f->UPB_ONLYBITS(offset), struct upb_Message*);
+  if (!sub_message) {
+    const upb_MiniTable* sub_mini_table =
+        upb_MiniTable_SubMessage(mini_table, f);
+    UPB_ASSERT(sub_mini_table);
+    sub_message = _upb_Message_New(sub_mini_table, arena);
+    *UPB_PTR_AT(msg, f->UPB_ONLYBITS(offset), struct upb_Message*) =
+        sub_message;
+    UPB_PRIVATE(_upb_Message_SetPresence)(msg, f);
+  }
+  return sub_message;
+}
+
+UPB_API_INLINE upb_StringView
+upb_Message_GetString(const struct upb_Message* msg,
+                      const upb_MiniTableField* f, upb_StringView default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_String ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Bytes);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             kUpb_FieldRep_StringView);
+
+  upb_MessageValue def;
+  def.str_val = default_val;
+  return upb_Message_GetField(msg, f, def).str_val;
+}
+
+UPB_API_INLINE uint32_t upb_Message_GetUInt32(const struct upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint32_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt32);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+
+  upb_MessageValue def;
+  def.uint32_val = default_val;
+  return upb_Message_GetField(msg, f, def).uint32_val;
+}
+
+UPB_API_INLINE uint64_t upb_Message_GetUInt64(const struct upb_Message* msg,
+                                              const upb_MiniTableField* f,
+                                              uint64_t default_val) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+
+  upb_MessageValue def;
+  def.uint64_val = default_val;
+  return upb_Message_GetField(msg, f, def).uint64_val;
+}
+
+// BaseField Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE void upb_Message_SetBaseFieldBool(struct upb_Message* msg,
+                                                 const upb_MiniTableField* f,
+                                                 bool value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Bool);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_1Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldDouble(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   double value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Double);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldFloat(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  float value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Float);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldInt32(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int32_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int32 ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Enum);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldInt64(struct upb_Message* msg,
+                                                  const upb_MiniTableField* f,
+                                                  int64_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Int64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldString(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   upb_StringView value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_String ||
+             upb_MiniTableField_CType(f) == kUpb_CType_Bytes);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) ==
+             kUpb_FieldRep_StringView);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt32(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint32_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt32);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetBaseFieldUInt64(struct upb_Message* msg,
+                                                   const upb_MiniTableField* f,
+                                                   uint64_t value) {
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_UInt64);
+  UPB_ASSUME(upb_MiniTableField_IsScalar(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_8Byte);
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+UPB_API_INLINE void upb_Message_SetClosedEnum(struct upb_Message* msg,
+                                              const upb_MiniTable* m,
+                                              const upb_MiniTableField* f,
+                                              int32_t value) {
+  UPB_ASSERT(upb_MiniTableField_IsClosedEnum(f));
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableField_GetRep)(f) == kUpb_FieldRep_4Byte);
+  UPB_ASSERT(
+      upb_MiniTableEnum_CheckValue(upb_MiniTable_GetSubEnumTable(m, f), value));
+  upb_Message_SetBaseField(msg, f, &value);
+}
+
+// Extension Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetExtensionBool(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, bool value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Bool);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_1Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionDouble(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, double value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Double);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionFloat(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, float value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Float);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int32_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Int32 ||
+             upb_MiniTableExtension_CType(e) == kUpb_CType_Enum);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, int64_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_Int64);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionString(
+    struct upb_Message* msg, const upb_MiniTableExtension* e,
+    upb_StringView value, upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_String ||
+             upb_MiniTableExtension_CType(e) == kUpb_CType_Bytes);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_StringView);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt32(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint32_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_UInt32);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_4Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+UPB_API_INLINE bool upb_Message_SetExtensionUInt64(
+    struct upb_Message* msg, const upb_MiniTableExtension* e, uint64_t value,
+    upb_Arena* a) {
+  UPB_ASSUME(upb_MiniTableExtension_CType(e) == kUpb_CType_UInt64);
+  UPB_ASSUME(UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(e) ==
+             kUpb_FieldRep_8Byte);
+  return upb_Message_SetExtension(msg, e, &value, a);
+}
+
+// Universal Setters ///////////////////////////////////////////////////////////
+
+UPB_API_INLINE bool upb_Message_SetBool(struct upb_Message* msg,
+                                        const upb_MiniTableField* f, bool value,
+                                        upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionBool(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldBool(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetDouble(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          double value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionDouble(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldDouble(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetFloat(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         float value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionFloat(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldFloat(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt32(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int32_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionInt32(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldInt32(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetInt64(struct upb_Message* msg,
+                                         const upb_MiniTableField* f,
+                                         int64_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionInt64(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldInt64(msg, f, value), true);
+}
+
+// Sets the value of a message-typed field. The mini_tables of `msg` and
+// `value` must have been linked for this to work correctly.
+UPB_API_INLINE void upb_Message_SetMessage(struct upb_Message* msg,
+                                           const upb_MiniTableField* f,
+                                           struct upb_Message* value) {
+  UPB_PRIVATE(_upb_Message_SetTaggedMessagePtr)
+  (msg, f, UPB_PRIVATE(_upb_TaggedMessagePtr_Pack)(value, false));
+}
+
+// Sets the value of a `string` or `bytes` field. The bytes of the value are not
+// copied, so it is the caller's responsibility to ensure that they remain valid
+// for the lifetime of `msg`. That might be done by copying them into the given
+// arena, or by fusing that arena with the arena the bytes live in, for example.
+UPB_API_INLINE bool upb_Message_SetString(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          upb_StringView value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionString(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldString(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt32(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint32_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionUInt32(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldUInt32(msg, f, value), true);
+}
+
+UPB_API_INLINE bool upb_Message_SetUInt64(struct upb_Message* msg,
+                                          const upb_MiniTableField* f,
+                                          uint64_t value, upb_Arena* a) {
+  return upb_MiniTableField_IsExtension(f)
+             ? upb_Message_SetExtensionUInt64(
+                   msg, (const upb_MiniTableExtension*)f, value, a)
+             : (upb_Message_SetBaseFieldUInt64(msg, f, value), true);
+}
+
 UPB_API_INLINE void upb_Message_Clear(struct upb_Message* msg,
                                       const upb_MiniTable* m) {
   UPB_ASSERT(!upb_Message_IsFrozen(msg));
@@ -335,33 +872,30 @@ UPB_API_INLINE void upb_Message_ClearExtension(
   }
 }
 
-UPB_INLINE void _upb_Message_AssertMapIsUntagged(
-    const struct upb_Message* msg, const upb_MiniTableField* field) {
-  UPB_UNUSED(msg);
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-#ifndef NDEBUG
-  uintptr_t default_val = 0;
-  uintptr_t tagged;
-  _upb_Message_GetNonExtensionField(msg, field, &default_val, &tagged);
-  UPB_ASSERT(!upb_TaggedMessagePtr_IsEmpty(tagged));
-#endif
+UPB_API_INLINE void upb_Message_ClearOneof(struct upb_Message* msg,
+                                           const upb_MiniTable* m,
+                                           const upb_MiniTableField* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+  uint32_t field_number = upb_Message_WhichOneofFieldNumber(msg, f);
+  if (field_number == 0) {
+    // No field in the oneof is set.
+    return;
+  }
+
+  const upb_MiniTableField* field =
+      upb_MiniTable_FindFieldByNumber(m, field_number);
+  upb_Message_ClearBaseField(msg, field);
 }
 
-UPB_INLINE struct upb_Map* _upb_Message_GetOrCreateMutableMap(
-    struct upb_Message* msg, const upb_MiniTableField* field, size_t key_size,
-    size_t val_size, upb_Arena* arena) {
-  UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-  _upb_Message_AssertMapIsUntagged(msg, field);
-  struct upb_Map* map = NULL;
-  struct upb_Map* default_map_value = NULL;
-  _upb_Message_GetNonExtensionField(msg, field, &default_map_value, &map);
-  if (!map) {
-    map = _upb_Map_New(arena, key_size, val_size);
-    // Check again due to: https://godbolt.org/z/7WfaoKG1r
-    UPB_PRIVATE(_upb_MiniTableField_CheckIsMap)(field);
-    upb_Message_SetBaseField(msg, field, &map);
+UPB_API_INLINE void* upb_Message_ResizeArrayUninitialized(
+    struct upb_Message* msg, const upb_MiniTableField* f, size_t size,
+    upb_Arena* arena) {
+  UPB_PRIVATE(_upb_MiniTableField_CheckIsArray)(f);
+  upb_Array* arr = upb_Message_GetOrCreateMutableArray(msg, f, arena);
+  if (!arr || !UPB_PRIVATE(_upb_Array_ResizeUninitialized)(arr, size, arena)) {
+    return NULL;
   }
-  return map;
+  return upb_Array_MutableDataPtr(arr);
 }
 
 #ifdef __cplusplus
diff --git a/upb/message/internal/extension.c b/upb/message/internal/extension.c
index 85a09fd2d0..f55253d495 100644
--- a/upb/message/internal/extension.c
+++ b/upb/message/internal/extension.c
@@ -49,6 +49,7 @@ const upb_Extension* UPB_PRIVATE(_upb_Message_Getexts)(
 
 upb_Extension* UPB_PRIVATE(_upb_Message_GetOrCreateExtension)(
     struct upb_Message* msg, const upb_MiniTableExtension* e, upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Extension* ext = (upb_Extension*)UPB_PRIVATE(_upb_Message_Getext)(msg, e);
   if (ext) return ext;
   if (!UPB_PRIVATE(_upb_Message_Realloc)(msg, sizeof(upb_Extension), a))
diff --git a/upb/message/internal/message.c b/upb/message/internal/message.c
index 856fc97016..57ab2d7371 100644
--- a/upb/message/internal/message.c
+++ b/upb/message/internal/message.c
@@ -23,6 +23,7 @@ const double kUpb_NaN = NAN;
 
 bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
                                        upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const size_t overhead = sizeof(upb_Message_Internal);
 
   upb_Message_Internal* in = UPB_PRIVATE(_upb_Message_GetInternal)(msg);
@@ -59,18 +60,16 @@ bool UPB_PRIVATE(_upb_Message_Realloc)(struct upb_Message* msg, size_t need,
 }
 
 #if UPB_TRACING_ENABLED
-static void (*_new_message_trace_handler)(const upb_MiniTable*,
-                                          const upb_Arena*);
+static void (*_message_trace_handler)(const upb_MiniTable*, const upb_Arena*);
 
-void UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(
-    void (*new_message_trace_handler)(const upb_MiniTable*, const upb_Arena*)) {
-  _new_message_trace_handler = new_message_trace_handler;
+void upb_Message_LogNewMessage(const upb_MiniTable* m, const upb_Arena* arena) {
+  if (_message_trace_handler) {
+    _message_trace_handler(m, arena);
+  }
 }
 
-void UPB_PRIVATE(upb_Message_LogNewMessage)(const upb_MiniTable* mini_table,
-                                            const upb_Arena* arena) {
-  if (_new_message_trace_handler) {
-    _new_message_trace_handler(mini_table, arena);
-  }
+void upb_Message_SetNewMessageTraceHandler(void (*handler)(const upb_MiniTable*,
+                                                           const upb_Arena*)) {
+  _message_trace_handler = handler;
 }
-#endif
+#endif  // UPB_TRACING_ENABLED
diff --git a/upb/message/internal/message.h b/upb/message/internal/message.h
index a81bb4f0b0..b371bbe0c8 100644
--- a/upb/message/internal/message.h
+++ b/upb/message/internal/message.h
@@ -60,18 +60,19 @@ typedef struct upb_Message_Internal {
 } upb_Message_Internal;
 
 #ifdef UPB_TRACING_ENABLED
-void UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(
-    void (*newMessageTraceHandler)(const upb_MiniTable*, const upb_Arena*));
-void UPB_PRIVATE(upb_Message_LogNewMessage)(const upb_MiniTable* mini_table,
-                                            const upb_Arena* arena);
-#endif
+UPB_API void upb_Message_LogNewMessage(const upb_MiniTable* m,
+                                       const upb_Arena* arena);
+UPB_API void upb_Message_SetNewMessageTraceHandler(
+    void (*handler)(const upb_MiniTable*, const upb_Arena*));
+#endif  // UPB_TRACING_ENABLED
 
 // Inline version upb_Message_New(), for internal use.
 UPB_INLINE struct upb_Message* _upb_Message_New(const upb_MiniTable* m,
                                                 upb_Arena* a) {
 #ifdef UPB_TRACING_ENABLED
-  UPB_PRIVATE(upb_Message_LogNewMessage)(m, a);
-#endif
+  upb_Message_LogNewMessage(m, a);
+#endif  // UPB_TRACING_ENABLED
+
   const int size = m->UPB_PRIVATE(size);
   struct upb_Message* msg = (struct upb_Message*)upb_Arena_Malloc(a, size);
   if (UPB_UNLIKELY(!msg)) return NULL;
diff --git a/upb/message/message.h b/upb/message/message.h
index cbcca84a72..50388fcb43 100644
--- a/upb/message/message.h
+++ b/upb/message/message.h
@@ -47,16 +47,12 @@ UPB_API void upb_Message_Freeze(upb_Message* msg, const upb_MiniTable* m);
 UPB_API_INLINE bool upb_Message_IsFrozen(const upb_Message* msg);
 
 #ifdef UPB_TRACING_ENABLED
-UPB_INLINE void upb_Message_SetNewMessageTraceHandler(
-    void (*newMessageTraceHandler)(const upb_MiniTable* mini_table,
-                                   const upb_Arena* arena)) {
-  UPB_PRIVATE(upb_Message_SetNewMessageTraceHandler)(newMessageTraceHandler);
-}
-UPB_INLINE void upb_Message_LogNewMessage(const upb_MiniTable* mini_table,
-                                          const upb_Arena* arena) {
-  UPB_PRIVATE(upb_Message_LogNewMessage)(mini_table, arena);
-}
-#endif
+UPB_API void upb_Message_LogNewMessage(const upb_MiniTable* m,
+                                       const upb_Arena* arena);
+
+UPB_API void upb_Message_SetNewMessageTraceHandler(
+    void (*handler)(const upb_MiniTable* m, const upb_Arena* arena));
+#endif  // UPB_TRACING_ENABLED
 
 #ifdef __cplusplus
 } /* extern "C" */
diff --git a/upb/message/promote.c b/upb/message/promote.c
index 51412e1781..566049245a 100644
--- a/upb/message/promote.c
+++ b/upb/message/promote.c
@@ -67,6 +67,7 @@ static upb_UnknownToMessageRet upb_MiniTable_ParseUnknownMessage(
 upb_GetExtension_Status upb_Message_GetOrPromoteExtension(
     upb_Message* msg, const upb_MiniTableExtension* ext_table,
     int decode_options, upb_Arena* arena, upb_MessageValue* value) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   UPB_ASSERT(upb_MiniTableExtension_CType(ext_table) == kUpb_CType_Message);
   const upb_Extension* extension =
       UPB_PRIVATE(_upb_Message_Getext)(msg, ext_table);
@@ -177,6 +178,7 @@ upb_DecodeStatus upb_Message_PromoteMessage(upb_Message* parent,
                                             int decode_options,
                                             upb_Arena* arena,
                                             upb_Message** promoted) {
+  UPB_ASSERT(!upb_Message_IsFrozen(parent));
   const upb_MiniTable* sub_table =
       upb_MiniTable_GetSubMessageTable(mini_table, field);
   UPB_ASSERT(sub_table);
@@ -186,7 +188,7 @@ upb_DecodeStatus upb_Message_PromoteMessage(upb_Message* parent,
       upb_Message_PromoteOne(&tagged, sub_table, decode_options, arena);
   if (ret == kUpb_DecodeStatus_Ok) {
     *promoted = upb_TaggedMessagePtr_GetNonEmptyMessage(tagged);
-    upb_Message_SetMessage(parent, mini_table, field, *promoted);
+    upb_Message_SetMessage(parent, field, *promoted);
   }
   return ret;
 }
@@ -233,6 +235,7 @@ upb_UnknownToMessageRet upb_MiniTable_PromoteUnknownToMessage(
     upb_Message* msg, const upb_MiniTable* mini_table,
     const upb_MiniTableField* field, const upb_MiniTable* sub_mini_table,
     int decode_options, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_FindUnknownRet unknown;
   // We need to loop and merge unknowns that have matching tag field->number.
   upb_Message* message = NULL;
@@ -277,7 +280,7 @@ upb_UnknownToMessageRet upb_MiniTable_PromoteUnknownToMessage(
     if (is_oneof) {
       UPB_PRIVATE(_upb_Message_SetOneofCase)(msg, field);
     }
-    upb_Message_SetMessage(msg, mini_table, field, message);
+    upb_Message_SetMessage(msg, field, message);
     ret.message = message;
   }
   return ret;
@@ -292,6 +295,8 @@ upb_UnknownToMessageRet upb_MiniTable_PromoteUnknownToMessage(
 upb_UnknownToMessage_Status upb_MiniTable_PromoteUnknownToMessageArray(
     upb_Message* msg, const upb_MiniTableField* field,
     const upb_MiniTable* mini_table, int decode_options, upb_Arena* arena) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+
   upb_Array* repeated_messages = upb_Message_GetMutableArray(msg, field);
   // Find all unknowns with given field number and parse.
   upb_FindUnknownRet unknown;
@@ -327,12 +332,11 @@ upb_UnknownToMessage_Status upb_MiniTable_PromoteUnknownToMessageArray(
 upb_UnknownToMessage_Status upb_MiniTable_PromoteUnknownToMap(
     upb_Message* msg, const upb_MiniTable* mini_table,
     const upb_MiniTableField* field, int decode_options, upb_Arena* arena) {
-  // TODO: use a variant of upb_MiniTable_GetSubMessageTable() here.
-  const upb_MiniTable* map_entry_mini_table = upb_MiniTableSub_Message(
-      mini_table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)]);
-  UPB_ASSERT(map_entry_mini_table);
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
+
+  const upb_MiniTable* map_entry_mini_table =
+      upb_MiniTable_MapEntrySubMessage(mini_table, field);
   UPB_ASSERT(upb_MiniTable_FieldCount(map_entry_mini_table) == 2);
-  UPB_ASSERT(upb_MiniTableField_IsMap(field));
   // Find all unknowns with given field number and parse.
   upb_FindUnknownRet unknown;
   while (1) {
diff --git a/upb/mini_descriptor/internal/encode_test.cc b/upb/mini_descriptor/internal/encode_test.cc
index 3ae2f6f56c..a84c739bbc 100644
--- a/upb/mini_descriptor/internal/encode_test.cc
+++ b/upb/mini_descriptor/internal/encode_test.cc
@@ -45,7 +45,7 @@ TEST_P(MiniTableTest, Empty) {
   upb_MiniTable* table =
       _upb_MiniTable_Build(nullptr, 0, GetParam(), arena.ptr(), status.ptr());
   ASSERT_NE(nullptr, table);
-  EXPECT_EQ(0, table->UPB_PRIVATE(field_count));
+  EXPECT_EQ(0, upb_MiniTable_FieldCount(table));
   EXPECT_EQ(0, table->UPB_PRIVATE(required_count));
 }
 
@@ -242,11 +242,11 @@ TEST_P(MiniTableTest, SubsInitializedToEmpty) {
   upb_MiniTable* table = _upb_MiniTable_Build(
       e.data().data(), e.data().size(), GetParam(), arena.ptr(), status.ptr());
   ASSERT_NE(nullptr, table);
-  EXPECT_EQ(table->UPB_PRIVATE(field_count), 2);
-  EXPECT_TRUE(UPB_PRIVATE(_upb_MiniTable_IsEmpty)(
-      upb_MiniTableSub_Message(table->UPB_PRIVATE(subs)[0])));
-  EXPECT_TRUE(UPB_PRIVATE(_upb_MiniTable_IsEmpty)(
-      upb_MiniTableSub_Message(table->UPB_PRIVATE(subs)[1])));
+  EXPECT_EQ(upb_MiniTable_FieldCount(table), 2);
+  EXPECT_FALSE(upb_MiniTable_FieldIsLinked(
+      table, upb_MiniTable_GetFieldByIndex(table, 0)));
+  EXPECT_FALSE(upb_MiniTable_FieldIsLinked(
+      table, upb_MiniTable_GetFieldByIndex(table, 1)));
 }
 
 TEST(MiniTableEnumTest, PositiveAndNegative) {
diff --git a/upb/mini_descriptor/link.c b/upb/mini_descriptor/link.c
index bc5fa2f65b..093150b623 100644
--- a/upb/mini_descriptor/link.c
+++ b/upb/mini_descriptor/link.c
@@ -50,12 +50,12 @@ bool upb_MiniTable_SetSubMessage(upb_MiniTable* table,
       return false;
   }
 
-  upb_MiniTableSub* table_sub =
-      (void*)&table->UPB_PRIVATE(subs)[field->UPB_PRIVATE(submsg_index)];
+  int idx = field->UPB_PRIVATE(submsg_index);
+  upb_MiniTableSub* table_subs = (void*)table->UPB_PRIVATE(subs);
   // TODO: Add this assert back once YouTube is updated to not call
   // this function repeatedly.
   // UPB_ASSERT(UPB_PRIVATE(_upb_MiniTable_IsEmpty)(table_sub->submsg));
-  *table_sub = upb_MiniTableSub_FromMessage(sub);
+  table_subs[idx] = upb_MiniTableSub_FromMessage(sub);
   return true;
 }
 
diff --git a/upb/mini_table/internal/extension.h b/upb/mini_table/internal/extension.h
index e326f99997..7220c5c6e0 100644
--- a/upb/mini_table/internal/extension.h
+++ b/upb/mini_table/internal/extension.h
@@ -8,6 +8,7 @@
 #ifndef UPB_MINI_TABLE_INTERNAL_EXTENSION_H_
 #define UPB_MINI_TABLE_INTERNAL_EXTENSION_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
 #include "upb/base/descriptor_constants.h"
@@ -41,6 +42,9 @@ upb_MiniTableExtension_Number(const struct upb_MiniTableExtension* e) {
 
 UPB_API_INLINE const struct upb_MiniTable* upb_MiniTableExtension_GetSubMessage(
     const struct upb_MiniTableExtension* e) {
+  if (upb_MiniTableExtension_CType(e) != kUpb_CType_Message) {
+    return NULL;
+  }
   return upb_MiniTableSub_Message(e->UPB_PRIVATE(sub));
 }
 
@@ -49,6 +53,11 @@ UPB_API_INLINE void upb_MiniTableExtension_SetSubMessage(
   e->UPB_PRIVATE(sub).UPB_PRIVATE(submsg) = m;
 }
 
+UPB_INLINE upb_FieldRep UPB_PRIVATE(_upb_MiniTableExtension_GetRep)(
+    const struct upb_MiniTableExtension* e) {
+  return UPB_PRIVATE(_upb_MiniTableField_GetRep)(&e->UPB_PRIVATE(field));
+}
+
 #ifdef __cplusplus
 } /* extern "C" */
 #endif
diff --git a/upb/mini_table/internal/message.h b/upb/mini_table/internal/message.h
index e044c0e48c..d5b1ae4e0b 100644
--- a/upb/mini_table/internal/message.h
+++ b/upb/mini_table/internal/message.h
@@ -8,8 +8,10 @@
 #ifndef UPB_MINI_TABLE_INTERNAL_MESSAGE_H_
 #define UPB_MINI_TABLE_INTERNAL_MESSAGE_H_
 
+#include <stddef.h>
 #include <stdint.h>
 
+#include "upb/base/descriptor_constants.h"
 #include "upb/mini_table/internal/field.h"
 #include "upb/mini_table/internal/sub.h"
 
@@ -97,34 +99,44 @@ UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_GetFieldByIndex(
   return &m->UPB_ONLYBITS(fields)[i];
 }
 
-UPB_INLINE const union upb_MiniTableSub* UPB_PRIVATE(
+UPB_INLINE const union upb_MiniTableSub UPB_PRIVATE(
     _upb_MiniTable_GetSubByIndex)(const struct upb_MiniTable* m, uint32_t i) {
-  return &m->UPB_PRIVATE(subs)[i];
+  return m->UPB_PRIVATE(subs)[i];
+}
+
+UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_SubMessage(
+    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
+  if (upb_MiniTableField_CType(f) != kUpb_CType_Message) {
+    return NULL;
+  }
+  return m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)].UPB_PRIVATE(submsg);
 }
 
 UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_GetSubMessageTable(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  UPB_ASSERT(upb_MiniTableField_CType(f) == kUpb_CType_Message);
-  const struct upb_MiniTable* ret = upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  UPB_ASSUME(upb_MiniTableField_CType(f) == kUpb_CType_Message);
+  const struct upb_MiniTable* ret = upb_MiniTable_SubMessage(m, f);
   UPB_ASSUME(ret);
   return UPB_PRIVATE(_upb_MiniTable_IsEmpty)(ret) ? NULL : ret;
 }
 
-UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_SubMessage(
+UPB_API_INLINE bool upb_MiniTable_FieldIsLinked(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  if (upb_MiniTableField_CType(f) != kUpb_CType_Message) {
-    return NULL;
-  }
-  return upb_MiniTableSub_Message(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  return upb_MiniTable_GetSubMessageTable(m, f) != NULL;
+}
+
+UPB_API_INLINE const struct upb_MiniTable* upb_MiniTable_MapEntrySubMessage(
+    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
+  UPB_ASSERT(upb_MiniTable_FieldIsLinked(m, f));  // Map entries must be linked.
+  UPB_ASSERT(upb_MiniTableField_IsMap(f));        // Function precondition.
+  return upb_MiniTable_SubMessage(m, f);
 }
 
 UPB_API_INLINE const struct upb_MiniTableEnum* upb_MiniTable_GetSubEnumTable(
     const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
   UPB_ASSERT(upb_MiniTableField_CType(f) == kUpb_CType_Enum);
-  return upb_MiniTableSub_Enum(
-      m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)]);
+  return m->UPB_PRIVATE(subs)[f->UPB_PRIVATE(submsg_index)].UPB_PRIVATE(
+      subenum);
 }
 
 UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_MapKey(
@@ -143,11 +155,6 @@ UPB_API_INLINE const struct upb_MiniTableField* upb_MiniTable_MapValue(
   return f;
 }
 
-UPB_API_INLINE bool upb_MiniTable_FieldIsLinked(
-    const struct upb_MiniTable* m, const struct upb_MiniTableField* f) {
-  return upb_MiniTable_GetSubMessageTable(m, f) != NULL;
-}
-
 // Computes a bitmask in which the |m->required_count| lowest bits are set.
 //
 // Sample output:
diff --git a/upb/mini_table/message.h b/upb/mini_table/message.h
index 1ce9087b0a..6589762f4e 100644
--- a/upb/mini_table/message.h
+++ b/upb/mini_table/message.h
@@ -34,10 +34,20 @@ UPB_API_INLINE int upb_MiniTable_FieldCount(const upb_MiniTable* m);
 UPB_API_INLINE const upb_MiniTable* upb_MiniTable_GetSubMessageTable(
     const upb_MiniTable* m, const upb_MiniTableField* f);
 
-// Returns the MiniTable for a message field if it is a submessage.
+// Returns the MiniTable for a message field if it is a submessage, otherwise
+// returns NULL.
+//
+// WARNING: if dynamic tree shaking is in use, the return value may be the
+// "empty", zero-field placeholder message instead of the real message type.
+// If the message is later linked, this function will begin returning the real
+// message type.
 UPB_API_INLINE const upb_MiniTable* upb_MiniTable_SubMessage(
     const upb_MiniTable* m, const upb_MiniTableField* f);
 
+// Returns the MiniTable for a map field.  The given field must refer to a map.
+UPB_API_INLINE const upb_MiniTable* upb_MiniTable_MapEntrySubMessage(
+    const upb_MiniTable* m, const upb_MiniTableField* f);
+
 // Returns the MiniTableEnum for a message field, NULL if the field is unlinked.
 UPB_API_INLINE const upb_MiniTableEnum* upb_MiniTable_GetSubEnumTable(
     const upb_MiniTable* m, const upb_MiniTableField* f);
diff --git a/upb/reflection/cmake/google/protobuf/descriptor.upb.h b/upb/reflection/cmake/google/protobuf/descriptor.upb.h
index fdedcbbab7..bdb3b5f6e0 100644
--- a/upb/reflection/cmake/google/protobuf/descriptor.upb.h
+++ b/upb/reflection/cmake/google/protobuf/descriptor.upb.h
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
diff --git a/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.c b/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.c
index eba76e82eb..80d12682e5 100644
--- a/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.c
+++ b/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.c
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #include <stddef.h>
 #include "upb/generated_code_support.h"
diff --git a/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.h b/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.h
index f48a64df65..4fc7176c59 100644
--- a/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.h
+++ b/upb/reflection/cmake/google/protobuf/descriptor.upb_minitable.h
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_MINITABLE_H_
diff --git a/upb/reflection/def.hpp b/upb/reflection/def.hpp
index 206f5db744..452ddc6e32 100644
--- a/upb/reflection/def.hpp
+++ b/upb/reflection/def.hpp
@@ -61,6 +61,13 @@ class FieldDefPtr {
     return upb_FieldDef_MiniTable(ptr_);
   }
 
+  std::string MiniDescriptorEncode() const {
+    upb::Arena arena;
+    upb_StringView md;
+    upb_FieldDef_MiniDescriptorEncode(ptr_, arena.ptr(), &md);
+    return std::string(md.data, md.size);
+  }
+
   const UPB_DESC(FieldOptions) * options() const {
     return upb_FieldDef_Options(ptr_);
   }
@@ -105,6 +112,7 @@ class FieldDefPtr {
   OneofDefPtr real_containing_oneof() const;
 
   // Convenient field type tests.
+  bool IsEnum() const { return upb_FieldDef_IsEnum(ptr_); }
   bool IsSubMessage() const { return upb_FieldDef_IsSubMessage(ptr_); }
   bool IsString() const { return upb_FieldDef_IsString(ptr_); }
   bool IsSequence() const { return upb_FieldDef_IsRepeated(ptr_); }
diff --git a/upb/reflection/field_def.c b/upb/reflection/field_def.c
index 98fa37092b..d5597f4b2e 100644
--- a/upb/reflection/field_def.c
+++ b/upb/reflection/field_def.c
@@ -208,11 +208,11 @@ upb_MessageValue upb_FieldDef_Default(const upb_FieldDef* f) {
 }
 
 const upb_MessageDef* upb_FieldDef_MessageSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_CType(f) == kUpb_CType_Message ? f->sub.msgdef : NULL;
+  return upb_FieldDef_IsSubMessage(f) ? f->sub.msgdef : NULL;
 }
 
 const upb_EnumDef* upb_FieldDef_EnumSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_CType(f) == kUpb_CType_Enum ? f->sub.enumdef : NULL;
+  return upb_FieldDef_IsEnum(f) ? f->sub.enumdef : NULL;
 }
 
 const upb_MiniTableField* upb_FieldDef_MiniTable(const upb_FieldDef* f) {
@@ -310,8 +310,11 @@ bool upb_FieldDef_HasDefault(const upb_FieldDef* f) { return f->has_default; }
 bool upb_FieldDef_HasPresence(const upb_FieldDef* f) { return f->has_presence; }
 
 bool upb_FieldDef_HasSubDef(const upb_FieldDef* f) {
-  return upb_FieldDef_IsSubMessage(f) ||
-         upb_FieldDef_CType(f) == kUpb_CType_Enum;
+  return upb_FieldDef_IsSubMessage(f) || upb_FieldDef_IsEnum(f);
+}
+
+bool upb_FieldDef_IsEnum(const upb_FieldDef* f) {
+  return upb_FieldDef_CType(f) == kUpb_CType_Enum;
 }
 
 bool upb_FieldDef_IsMap(const upb_FieldDef* f) {
diff --git a/upb/reflection/field_def.h b/upb/reflection/field_def.h
index a4019a0aa0..98f4a875d0 100644
--- a/upb/reflection/field_def.h
+++ b/upb/reflection/field_def.h
@@ -45,6 +45,7 @@ bool upb_FieldDef_HasOptions(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_HasPresence(const upb_FieldDef* f);
 bool upb_FieldDef_HasSubDef(const upb_FieldDef* f);
 uint32_t upb_FieldDef_Index(const upb_FieldDef* f);
+UPB_API bool upb_FieldDef_IsEnum(const upb_FieldDef* f);
 bool upb_FieldDef_IsExtension(const upb_FieldDef* f);
 UPB_API bool upb_FieldDef_IsMap(const upb_FieldDef* f);
 bool upb_FieldDef_IsOptional(const upb_FieldDef* f);
diff --git a/upb/reflection/message.c b/upb/reflection/message.c
index b0c4a401c3..9211738c33 100644
--- a/upb/reflection/message.c
+++ b/upb/reflection/message.c
@@ -65,6 +65,7 @@ upb_MessageValue upb_Message_GetFieldByDef(const upb_Message* msg,
 upb_MutableMessageValue upb_Message_Mutable(upb_Message* msg,
                                             const upb_FieldDef* f,
                                             upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   UPB_ASSERT(upb_FieldDef_IsSubMessage(f) || upb_FieldDef_IsRepeated(f));
   if (upb_FieldDef_HasPresence(f) && !upb_Message_HasFieldByDef(msg, f)) {
     // We need to skip the upb_Message_GetFieldByDef() call in this case.
@@ -103,6 +104,7 @@ make:
 
 bool upb_Message_SetFieldByDef(upb_Message* msg, const upb_FieldDef* f,
                                upb_MessageValue val, upb_Arena* a) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_MiniTableField* m_f = upb_FieldDef_MiniTable(f);
 
   if (upb_MiniTableField_IsExtension(m_f)) {
@@ -115,6 +117,7 @@ bool upb_Message_SetFieldByDef(upb_Message* msg, const upb_FieldDef* f,
 }
 
 void upb_Message_ClearFieldByDef(upb_Message* msg, const upb_FieldDef* f) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   const upb_MiniTableField* m_f = upb_FieldDef_MiniTable(f);
 
   if (upb_MiniTableField_IsExtension(m_f)) {
@@ -125,6 +128,7 @@ void upb_Message_ClearFieldByDef(upb_Message* msg, const upb_FieldDef* f) {
 }
 
 void upb_Message_ClearByDef(upb_Message* msg, const upb_MessageDef* m) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_Message_Clear(msg, upb_MessageDef_MiniTable(m));
 }
 
@@ -186,6 +190,7 @@ bool upb_Message_Next(const upb_Message* msg, const upb_MessageDef* m,
 
 bool _upb_Message_DiscardUnknown(upb_Message* msg, const upb_MessageDef* m,
                                  int depth) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   size_t iter = kUpb_Message_Begin;
   const upb_FieldDef* f;
   upb_MessageValue val;
diff --git a/upb/reflection/stage0/google/protobuf/descriptor.upb.h b/upb/reflection/stage0/google/protobuf/descriptor.upb.h
index 33287809bf..9bc4bbbb14 100644
--- a/upb/reflection/stage0/google/protobuf/descriptor.upb.h
+++ b/upb/reflection/stage0/google/protobuf/descriptor.upb.h
@@ -3,7 +3,8 @@
  *     google/protobuf/descriptor.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_DESCRIPTOR_PROTO_UPB_H_
diff --git a/upb/wire/internal/decode_fast.c b/upb/wire/internal/decode_fast.c
index 67be4135c4..726f65ad24 100644
--- a/upb/wire/internal/decode_fast.c
+++ b/upb/wire/internal/decode_fast.c
@@ -231,6 +231,7 @@ UPB_FORCEINLINE
 void* fastdecode_getfield(upb_Decoder* d, const char* ptr, upb_Message* msg,
                           uint64_t* data, uint64_t* hasbits,
                           fastdecode_arr* farr, int valbytes, upb_card card) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   switch (card) {
     case CARD_s: {
       uint8_t hasbit_index = *data >> 24;
@@ -606,6 +607,7 @@ UPB_NOINLINE
 static const char* fastdecode_verifyutf8(upb_Decoder* d, const char* ptr,
                                          upb_Message* msg, intptr_t table,
                                          uint64_t hasbits, uint64_t data) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView* dst = (upb_StringView*)data;
   if (!_upb_Decoder_VerifyUtf8Inline(dst->data, dst->size)) {
     _upb_FastDecoder_ErrorJmp(d, kUpb_DecodeStatus_BadUtf8);
@@ -651,6 +653,7 @@ UPB_NOINLINE
 static const char* fastdecode_longstring_noutf8(
     struct upb_Decoder* d, const char* ptr, upb_Message* msg, intptr_t table,
     uint64_t hasbits, uint64_t data) {
+  UPB_ASSERT(!upb_Message_IsFrozen(msg));
   upb_StringView* dst = (upb_StringView*)data;
   FASTDECODE_LONGSTRING(d, ptr, msg, table, hasbits, dst, false);
 }
diff --git a/upb_generator/BUILD b/upb_generator/BUILD
index 56b211d748..757d840af5 100644
--- a/upb_generator/BUILD
+++ b/upb_generator/BUILD
@@ -409,27 +409,3 @@ proto_lang_toolchain(
     runtime = "//upb:generated_reflection_support__only_for_generated_code_do_not_use__i_give_permission_to_break_me",
     visibility = ["//visibility:public"],
 )
-
-cc_binary(
-    name = "protoc-gen-upbdev",
-    srcs = [
-        "protoc-gen-upbdev.cc",
-        "subprocess.cc",
-        "subprocess.h",
-    ],
-    copts = UPB_DEFAULT_CPPOPTS,
-    target_compatible_with = select({
-        "@platforms//os:windows": ["@platforms//:incompatible"],
-        "//conditions:default": [],
-    }),
-    visibility = ["//visibility:public"],
-    deps = [
-        ":plugin_upb_proto",
-        ":upbdev",
-        "//upb:base",
-        "//upb:mem",
-        "//upb:port",
-        "@com_google_absl//absl/log:absl_log",
-        "@com_google_absl//absl/strings",
-    ],
-)
diff --git a/upb_generator/cmake/google/protobuf/compiler/plugin.upb.h b/upb_generator/cmake/google/protobuf/compiler/plugin.upb.h
index 364bc2e2e5..ee7ad4f82d 100644
--- a/upb_generator/cmake/google/protobuf/compiler/plugin.upb.h
+++ b/upb_generator/cmake/google/protobuf/compiler/plugin.upb.h
@@ -3,7 +3,8 @@
  *     google/protobuf/compiler/plugin.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_COMPILER_PLUGIN_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_COMPILER_PLUGIN_PROTO_UPB_H_
diff --git a/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.c b/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.c
index 3f24240c57..9fc1582433 100644
--- a/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.c
+++ b/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.c
@@ -3,7 +3,8 @@
  *     google/protobuf/compiler/plugin.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #include <stddef.h>
 #include "upb/generated_code_support.h"
diff --git a/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.h b/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.h
index f66ce47047..b9d777cb46 100644
--- a/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.h
+++ b/upb_generator/cmake/google/protobuf/compiler/plugin.upb_minitable.h
@@ -3,7 +3,8 @@
  *     google/protobuf/compiler/plugin.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_COMPILER_PLUGIN_PROTO_UPB_MINITABLE_H_
 #define GOOGLE_PROTOBUF_COMPILER_PLUGIN_PROTO_UPB_MINITABLE_H_
diff --git a/upb_generator/common.cc b/upb_generator/common.cc
index 3bda1a3cab..f7f408128e 100644
--- a/upb_generator/common.cc
+++ b/upb_generator/common.cc
@@ -51,7 +51,11 @@ void EmitFileWarning(absl::string_view name, Output& output) {
       " *     $0\n"
       " *\n"
       " * Do not edit -- your changes will be discarded when the file is\n"
-      " * regenerated. */\n\n",
+      " * regenerated.\n"
+      " * NO CHECKED-IN "
+      // Intentional line break.
+      "PROTOBUF GENCODE */\n"
+      "\n",
       name);
 }
 
diff --git a/upb_generator/protoc-gen-upbdev.cc b/upb_generator/protoc-gen-upbdev.cc
deleted file mode 100644
index 801a2c8438..0000000000
--- a/upb_generator/protoc-gen-upbdev.cc
+++ /dev/null
@@ -1,71 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2023 Google LLC.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-#include <iostream>
-#include <string>
-
-#include "google/protobuf/compiler/plugin.upb.h"
-#include "upb/base/status.h"
-#include "upb/base/string_view.h"
-#include "upb/mem/arena.h"
-#include "upb_generator/subprocess.h"
-#include "upb_generator/upbdev.h"
-
-static constexpr char kDefaultPlugin[] = "protoc_dart_plugin";
-
-int main() {
-  upb_Arena* a = upb_Arena_New();
-  upb_Status status;
-  upb_Status_Clear(&status);
-
-  // Read (binary) stdin into a string.
-  const std::string input = {std::istreambuf_iterator<char>(std::cin),
-                             std::istreambuf_iterator<char>()};
-
-  // Parse the request.
-  auto inner_request = google_protobuf_compiler_CodeGeneratorRequest_parse(
-      input.c_str(), input.size(), a);
-
-  // Check the request for a plugin name.
-  std::string plugin = kDefaultPlugin;
-  if (google_protobuf_compiler_CodeGeneratorRequest_has_parameter(inner_request)) {
-    auto param = google_protobuf_compiler_CodeGeneratorRequest_parameter(inner_request);
-    plugin = std::string(param.data, param.size);
-  }
-
-  // Wrap the request inside a upb_CodeGeneratorRequest and JSON-encode it.
-  const upb_StringView sv =
-      upbdev_ProcessInput(input.data(), input.size(), a, &status);
-  if (!upb_Status_IsOk(&status)) {
-    std::cerr << status.msg << '\n';
-    return -1;
-  }
-
-  // Launch the subprocess.
-  upb::generator::Subprocess subprocess;
-  subprocess.Start(plugin, upb::generator::Subprocess::SEARCH_PATH);
-
-  // Exchange JSON strings with the subprocess.
-  const std::string json_request = std::string(sv.data, sv.size);
-  std::string json_response, error;
-  const bool ok = subprocess.Communicate(json_request, &json_response, &error);
-  if (!ok) {
-    // Dump the JSON request to stderr if we can't launch the next plugin.
-    std::cerr << json_request << '\n';
-    return -1;
-  }
-
-  // Decode, serialize, and write the JSON response.
-  upbdev_ProcessOutput(json_response.data(), json_response.size(), a, &status);
-  if (!upb_Status_IsOk(&status)) {
-    std::cerr << status.msg << '\n';
-    return -1;
-  }
-
-  upb_Arena_Free(a);
-  return 0;
-}
diff --git a/upb_generator/stage0/google/protobuf/compiler/plugin.upb.h b/upb_generator/stage0/google/protobuf/compiler/plugin.upb.h
index 1ccffa7b7e..50c2d24823 100644
--- a/upb_generator/stage0/google/protobuf/compiler/plugin.upb.h
+++ b/upb_generator/stage0/google/protobuf/compiler/plugin.upb.h
@@ -3,7 +3,8 @@
  *     google/protobuf/compiler/plugin.proto
  *
  * Do not edit -- your changes will be discarded when the file is
- * regenerated. */
+ * regenerated.
+ * NO CHECKED-IN PROTOBUF GENCODE */
 
 #ifndef GOOGLE_PROTOBUF_COMPILER_PLUGIN_PROTO_UPB_H_
 #define GOOGLE_PROTOBUF_COMPILER_PLUGIN_PROTO_UPB_H_
diff --git a/upb_generator/subprocess.cc b/upb_generator/subprocess.cc
deleted file mode 100644
index 6831f656b7..0000000000
--- a/upb_generator/subprocess.cc
+++ /dev/null
@@ -1,444 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2023 Google LLC.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-// Shamelessly copied from the protobuf compiler's subprocess.cc
-// except this version passes strings instead of Messages.
-
-#include "upb_generator/subprocess.h"
-
-#include <algorithm>
-#include <cstring>
-#include <iostream>
-
-#ifndef _MSVC_LANG
-#include <errno.h>
-#include <signal.h>
-#include <sys/select.h>
-#include <sys/wait.h>
-#endif
-
-#include "absl/log/absl_log.h"
-#include "absl/strings/substitute.h"
-
-// Must be last.
-#include "upb/port/def.inc"
-
-namespace upb {
-namespace generator {
-
-namespace {
-char* portable_strdup(const char* s) {
-  char* ns = (char*)malloc(strlen(s) + 1);
-  if (ns != nullptr) {
-    strcpy(ns, s);
-  }
-  return ns;
-}
-}  // namespace
-
-#ifdef _WIN32
-
-static void CloseHandleOrDie(HANDLE handle) {
-  if (!CloseHandle(handle)) {
-    ABSL_LOG(FATAL) << "CloseHandle: "
-                    << Subprocess::Win32ErrorMessage(GetLastError());
-  }
-}
-
-Subprocess::Subprocess()
-    : process_start_error_(ERROR_SUCCESS),
-      child_handle_(nullptr),
-      child_stdin_(nullptr),
-      child_stdout_(nullptr) {}
-
-Subprocess::~Subprocess() {
-  if (child_stdin_ != nullptr) {
-    CloseHandleOrDie(child_stdin_);
-  }
-  if (child_stdout_ != nullptr) {
-    CloseHandleOrDie(child_stdout_);
-  }
-}
-
-void Subprocess::Start(const std::string& program, SearchMode search_mode) {
-  // Create the pipes.
-  HANDLE stdin_pipe_read;
-  HANDLE stdin_pipe_write;
-  HANDLE stdout_pipe_read;
-  HANDLE stdout_pipe_write;
-
-  if (!CreatePipe(&stdin_pipe_read, &stdin_pipe_write, nullptr, 0)) {
-    ABSL_LOG(FATAL) << "CreatePipe: " << Win32ErrorMessage(GetLastError());
-  }
-  if (!CreatePipe(&stdout_pipe_read, &stdout_pipe_write, nullptr, 0)) {
-    ABSL_LOG(FATAL) << "CreatePipe: " << Win32ErrorMessage(GetLastError());
-  }
-
-  // Make child side of the pipes inheritable.
-  if (!SetHandleInformation(stdin_pipe_read, HANDLE_FLAG_INHERIT,
-                            HANDLE_FLAG_INHERIT)) {
-    ABSL_LOG(FATAL) << "SetHandleInformation: "
-                    << Win32ErrorMessage(GetLastError());
-  }
-  if (!SetHandleInformation(stdout_pipe_write, HANDLE_FLAG_INHERIT,
-                            HANDLE_FLAG_INHERIT)) {
-    ABSL_LOG(FATAL) << "SetHandleInformation: "
-                    << Win32ErrorMessage(GetLastError());
-  }
-
-  // Setup STARTUPINFO to redirect handles.
-  STARTUPINFOA startup_info;
-  ZeroMemory(&startup_info, sizeof(startup_info));
-  startup_info.cb = sizeof(startup_info);
-  startup_info.dwFlags = STARTF_USESTDHANDLES;
-  startup_info.hStdInput = stdin_pipe_read;
-  startup_info.hStdOutput = stdout_pipe_write;
-  startup_info.hStdError = GetStdHandle(STD_ERROR_HANDLE);
-
-  if (startup_info.hStdError == INVALID_HANDLE_VALUE) {
-    ABSL_LOG(FATAL) << "GetStdHandle: " << Win32ErrorMessage(GetLastError());
-  }
-
-  // Invoking cmd.exe allows for '.bat' files from the path as well as '.exe'.
-  // Using a malloc'ed string because CreateProcess() can mutate its second
-  // parameter.
-  char* command_line =
-      portable_strdup(("cmd.exe /c \"" + program + "\"").c_str());
-
-  // Create the process.
-  PROCESS_INFORMATION process_info;
-
-  if (CreateProcessA((search_mode == SEARCH_PATH) ? nullptr : program.c_str(),
-                     (search_mode == SEARCH_PATH) ? command_line : nullptr,
-                     nullptr,  // process security attributes
-                     nullptr,  // thread security attributes
-                     TRUE,     // inherit handles?
-                     0,        // obscure creation flags
-                     nullptr,  // environment (inherit from parent)
-                     nullptr,  // current directory (inherit from parent)
-                     &startup_info, &process_info)) {
-    child_handle_ = process_info.hProcess;
-    CloseHandleOrDie(process_info.hThread);
-    child_stdin_ = stdin_pipe_write;
-    child_stdout_ = stdout_pipe_read;
-  } else {
-    process_start_error_ = GetLastError();
-    CloseHandleOrDie(stdin_pipe_write);
-    CloseHandleOrDie(stdout_pipe_read);
-  }
-
-  CloseHandleOrDie(stdin_pipe_read);
-  CloseHandleOrDie(stdout_pipe_write);
-  free(command_line);
-}
-
-bool Subprocess::Communicate(const std::string& input_data,
-                             std::string* output_data, std::string* error) {
-  if (process_start_error_ != ERROR_SUCCESS) {
-    *error = Win32ErrorMessage(process_start_error_);
-    return false;
-  }
-
-  GOOGLE_CHECK(child_handle_ != nullptr) << "Must call Start() first.";
-
-  int input_pos = 0;
-
-  while (child_stdout_ != nullptr) {
-    HANDLE handles[2];
-    int handle_count = 0;
-
-    if (child_stdin_ != nullptr) {
-      handles[handle_count++] = child_stdin_;
-    }
-    if (child_stdout_ != nullptr) {
-      handles[handle_count++] = child_stdout_;
-    }
-
-    DWORD wait_result =
-        WaitForMultipleObjects(handle_count, handles, FALSE, INFINITE);
-
-    HANDLE signaled_handle = nullptr;
-    if (wait_result >= WAIT_OBJECT_0 &&
-        wait_result < WAIT_OBJECT_0 + handle_count) {
-      signaled_handle = handles[wait_result - WAIT_OBJECT_0];
-    } else if (wait_result == WAIT_FAILED) {
-      ABSL_LOG(FATAL) << "WaitForMultipleObjects: "
-                      << Win32ErrorMessage(GetLastError());
-    } else {
-      ABSL_LOG(FATAL) << "WaitForMultipleObjects: Unexpected return code: "
-                      << wait_result;
-    }
-
-    if (signaled_handle == child_stdin_) {
-      DWORD n;
-      if (!WriteFile(child_stdin_, input_data.data() + input_pos,
-                     input_data.size() - input_pos, &n, nullptr)) {
-        // Child closed pipe.  Presumably it will report an error later.
-        // Pretend we're done for now.
-        input_pos = input_data.size();
-      } else {
-        input_pos += n;
-      }
-
-      if (input_pos == input_data.size()) {
-        // We're done writing.  Close.
-        CloseHandleOrDie(child_stdin_);
-        child_stdin_ = nullptr;
-      }
-    } else if (signaled_handle == child_stdout_) {
-      char buffer[4096];
-      DWORD n;
-
-      if (!ReadFile(child_stdout_, buffer, sizeof(buffer), &n, nullptr)) {
-        // We're done reading.  Close.
-        CloseHandleOrDie(child_stdout_);
-        child_stdout_ = nullptr;
-      } else {
-        output_data->append(buffer, n);
-      }
-    }
-  }
-
-  if (child_stdin_ != nullptr) {
-    // Child did not finish reading input before it closed the output.
-    // Presumably it exited with an error.
-    CloseHandleOrDie(child_stdin_);
-    child_stdin_ = nullptr;
-  }
-
-  DWORD wait_result = WaitForSingleObject(child_handle_, INFINITE);
-
-  if (wait_result == WAIT_FAILED) {
-    ABSL_LOG(FATAL) << "WaitForSingleObject: "
-                    << Win32ErrorMessage(GetLastError());
-  } else if (wait_result != WAIT_OBJECT_0) {
-    ABSL_LOG(FATAL) << "WaitForSingleObject: Unexpected return code: "
-                    << wait_result;
-  }
-
-  DWORD exit_code;
-  if (!GetExitCodeProcess(child_handle_, &exit_code)) {
-    ABSL_LOG(FATAL) << "GetExitCodeProcess: "
-                    << Win32ErrorMessage(GetLastError());
-  }
-
-  CloseHandleOrDie(child_handle_);
-  child_handle_ = nullptr;
-
-  if (exit_code != 0) {
-    *error = absl::Substitute("Plugin failed with status code $0.", exit_code);
-    return false;
-  }
-
-  return true;
-}
-
-std::string Subprocess::Win32ErrorMessage(DWORD error_code) {
-  char* message;
-
-  // WTF?
-  FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
-                     FORMAT_MESSAGE_IGNORE_INSERTS,
-                 nullptr, error_code,
-                 MAKELANGID(LANG_ENGLISH, SUBLANG_ENGLISH_US),
-                 (LPSTR)&message,  // NOT A BUG!
-                 0, nullptr);
-
-  std::string result = message;
-  LocalFree(message);
-  return result;
-}
-
-// ===================================================================
-
-#else  // _WIN32
-
-Subprocess::Subprocess()
-    : child_pid_(-1), child_stdin_(-1), child_stdout_(-1) {}
-
-Subprocess::~Subprocess() {
-  if (child_stdin_ != -1) {
-    close(child_stdin_);
-  }
-  if (child_stdout_ != -1) {
-    close(child_stdout_);
-  }
-}
-
-void Subprocess::Start(const std::string& program, SearchMode search_mode) {
-  // Note that we assume that there are no other threads, thus we don't have to
-  // do crazy stuff like using socket pairs or avoiding libc locks.
-
-  // [0] is read end, [1] is write end.
-  int stdin_pipe[2];
-  int stdout_pipe[2];
-
-  int p0 = pipe(stdin_pipe);
-  int p1 = pipe(stdout_pipe);
-  UPB_ASSERT(p0 != -1);
-  UPB_ASSERT(p1 != -1);
-
-  char* argv[2] = {portable_strdup(program.c_str()), nullptr};
-
-  child_pid_ = fork();
-  if (child_pid_ == -1) {
-    std::cerr << "fork: " << strerror(errno);
-  } else if (child_pid_ == 0) {
-    // We are the child.
-    dup2(stdin_pipe[0], STDIN_FILENO);
-    dup2(stdout_pipe[1], STDOUT_FILENO);
-
-    close(stdin_pipe[0]);
-    close(stdin_pipe[1]);
-    close(stdout_pipe[0]);
-    close(stdout_pipe[1]);
-
-    switch (search_mode) {
-      case SEARCH_PATH:
-        execvp(argv[0], argv);
-        break;
-      case EXACT_NAME:
-        execv(argv[0], argv);
-        break;
-    }
-
-    // Write directly to STDERR_FILENO to avoid stdio code paths that may do
-    // stuff that is unsafe here.
-    int ignored;
-    ignored = write(STDERR_FILENO, argv[0], strlen(argv[0]));
-    const char* message =
-        ": program not found or is not executable\n"
-        "Please specify a program using absolute path or make sure "
-        "the program is available in your PATH system variable\n";
-    ignored = write(STDERR_FILENO, message, strlen(message));
-    (void)ignored;
-
-    // Must use _exit() rather than exit() to avoid flushing output buffers
-    // that will also be flushed by the parent.
-    _exit(1);
-  } else {
-    free(argv[0]);
-
-    close(stdin_pipe[0]);
-    close(stdout_pipe[1]);
-
-    child_stdin_ = stdin_pipe[1];
-    child_stdout_ = stdout_pipe[0];
-  }
-}
-
-bool Subprocess::Communicate(const std::string& input_data,
-                             std::string* output_data, std::string* error) {
-  if (child_stdin_ == -1) {
-    std::cerr << "Must call Start() first." << '\n';
-    UPB_ASSERT(child_stdin_ != -1);
-  }
-
-  // The "sighandler_t" typedef is GNU-specific, so define our own.
-  typedef void SignalHandler(int);
-
-  // Make sure SIGPIPE is disabled so that if the child dies it doesn't kill us.
-  SignalHandler* old_pipe_handler = signal(SIGPIPE, SIG_IGN);
-
-  int input_pos = 0;
-  int max_fd = std::max(child_stdin_, child_stdout_);
-
-  while (child_stdout_ != -1) {
-    fd_set read_fds;
-    fd_set write_fds;
-    FD_ZERO(&read_fds);
-    FD_ZERO(&write_fds);
-    if (child_stdout_ != -1) {
-      FD_SET(child_stdout_, &read_fds);
-    }
-    if (child_stdin_ != -1) {
-      FD_SET(child_stdin_, &write_fds);
-    }
-
-    if (select(max_fd + 1, &read_fds, &write_fds, nullptr, nullptr) < 0) {
-      if (errno == EINTR) {
-        // Interrupted by signal.  Try again.
-        continue;
-      } else {
-        std::cerr << "select: " << strerror(errno) << '\n';
-        UPB_ASSERT(0);
-      }
-    }
-
-    if (child_stdin_ != -1 && FD_ISSET(child_stdin_, &write_fds)) {
-      int n = write(child_stdin_, input_data.data() + input_pos,
-                    input_data.size() - input_pos);
-      if (n < 0) {
-        // Child closed pipe.  Presumably it will report an error later.
-        // Pretend we're done for now.
-        input_pos = input_data.size();
-      } else {
-        input_pos += n;
-      }
-
-      if (input_pos == (int)input_data.size()) {
-        // We're done writing.  Close.
-        close(child_stdin_);
-        child_stdin_ = -1;
-      }
-    }
-
-    if (child_stdout_ != -1 && FD_ISSET(child_stdout_, &read_fds)) {
-      char buffer[4096];
-      int n = read(child_stdout_, buffer, sizeof(buffer));
-
-      if (n > 0) {
-        output_data->append(buffer, (size_t)n);
-      } else {
-        // We're done reading.  Close.
-        close(child_stdout_);
-        child_stdout_ = -1;
-      }
-    }
-  }
-
-  if (child_stdin_ != -1) {
-    // Child did not finish reading input before it closed the output.
-    // Presumably it exited with an error.
-    close(child_stdin_);
-    child_stdin_ = -1;
-  }
-
-  int status;
-  while (waitpid(child_pid_, &status, 0) == -1) {
-    if (errno != EINTR) {
-      std::cerr << "waitpid: " << strerror(errno) << '\n';
-      UPB_ASSERT(0);
-    }
-  }
-
-  // Restore SIGPIPE handling.
-  signal(SIGPIPE, old_pipe_handler);
-
-  if (WIFEXITED(status)) {
-    if (WEXITSTATUS(status) != 0) {
-      int error_code = WEXITSTATUS(status);
-      *error =
-          absl::Substitute("Plugin failed with status code $0.", error_code);
-      return false;
-    }
-  } else if (WIFSIGNALED(status)) {
-    int signal = WTERMSIG(status);
-    *error = absl::Substitute("Plugin killed by signal $0.", signal);
-    return false;
-  } else {
-    *error = "Neither WEXITSTATUS nor WTERMSIG is true?";
-    return false;
-  }
-
-  return true;
-}
-
-#endif  // !_WIN32
-
-}  // namespace generator
-}  // namespace upb
diff --git a/upb_generator/subprocess.h b/upb_generator/subprocess.h
deleted file mode 100644
index 731969083f..0000000000
--- a/upb_generator/subprocess.h
+++ /dev/null
@@ -1,81 +0,0 @@
-// Protocol Buffers - Google's data interchange format
-// Copyright 2023 Google LLC.  All rights reserved.
-//
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file or at
-// https://developers.google.com/open-source/licenses/bsd
-
-// Shamelessly copied from the protobuf compiler's subprocess.h
-// except this version passes strings instead of Messages.
-
-#ifndef THIRD_PARTY_UPB_UPB_GENERATOR_H_
-#define THIRD_PARTY_UPB_UPB_GENERATOR_H_
-
-#ifdef _WIN32
-#ifndef WIN32_LEAN_AND_MEAN
-#define WIN32_LEAN_AND_MEAN  // right...
-#endif
-#include <windows.h>
-#else  // _WIN32
-#include <sys/types.h>
-#include <unistd.h>
-#endif  // !_WIN32
-#include <string>
-
-namespace upb {
-namespace generator {
-
-// Utility class for launching sub-processes.
-class Subprocess {
- public:
-  Subprocess();
-  ~Subprocess();
-
-  enum SearchMode {
-    SEARCH_PATH,  // Use PATH environment variable.
-    EXACT_NAME    // Program is an exact file name; don't use the PATH.
-  };
-
-  // Start the subprocess.  Currently we don't provide a way to specify
-  // arguments as protoc plugins don't have any.
-  void Start(const std::string& program, SearchMode search_mode);
-
-  // Pipe the input message to the subprocess's stdin, then close the pipe.
-  // Meanwhile, read from the subprocess's stdout and copy into *output.
-  // All this is done carefully to avoid deadlocks.
-  // Returns true if successful.  On any sort of error, returns false and sets
-  // *error to a description of the problem.
-  bool Communicate(const std::string& input_data, std::string* output_data,
-                   std::string* error);
-
-#ifdef _WIN32
-  // Given an error code, returns a human-readable error message.  This is
-  // defined here so that CommandLineInterface can share it.
-  static std::string Win32ErrorMessage(DWORD error_code);
-#endif
-
- private:
-#ifdef _WIN32
-  DWORD process_start_error_;
-  HANDLE child_handle_;
-
-  // The file handles for our end of the child's pipes.  We close each and
-  // set it to NULL when no longer needed.
-  HANDLE child_stdin_;
-  HANDLE child_stdout_;
-
-#else  // _WIN32
-  pid_t child_pid_;
-
-  // The file descriptors for our end of the child's pipes.  We close each and
-  // set it to -1 when no longer needed.
-  int child_stdin_;
-  int child_stdout_;
-
-#endif  // !_WIN32
-};
-
-}  // namespace generator
-}  // namespace upb
-
-#endif  // THIRD_PARTY_UPB_UPB_GENERATOR_H_
diff --git a/upb_generator/upbdev.c b/upb_generator/upbdev.c
index 1a48621a9b..4246919564 100644
--- a/upb_generator/upbdev.c
+++ b/upb_generator/upbdev.c
@@ -83,8 +83,9 @@ upb_StringView upbdev_ProcessInput(const char* buf, size_t size,
   return upbc_JsonEncode(outer_request, arena, status);
 }
 
-upb_StringView upbdev_ProcessOutput(const char* buf, size_t size,
-                                    upb_Arena* arena, upb_Status* status) {
+static upb_StringView upbdev_ProcessOutput(const char* buf, size_t size,
+                                           upb_Arena* arena,
+                                           upb_Status* status) {
   upb_StringView out = {.data = NULL, .size = 0};
 
   const google_protobuf_compiler_CodeGeneratorResponse* response =
diff --git a/upb_generator/upbdev.h b/upb_generator/upbdev.h
index ee5b0a8aa9..a5fd0f12aa 100644
--- a/upb_generator/upbdev.h
+++ b/upb_generator/upbdev.h
@@ -25,11 +25,6 @@ UPB_API upb_StringView upbdev_ProcessInput(const char* buf, size_t size,
                                            upb_Arena* arena,
                                            upb_Status* status);
 
-// Decode |buf| from JSON, serialize to wire format, and return it.
-UPB_API upb_StringView upbdev_ProcessOutput(const char* buf, size_t size,
-                                            upb_Arena* arena,
-                                            upb_Status* status);
-
 // Decode |buf| from JSON, serialize to wire format, and write it to stdout.
 UPB_API void upbdev_ProcessStdout(const char* buf, size_t size,
                                   upb_Arena* arena, upb_Status* status);