Rust: set up a new crate for the well-known types

It's not yet possible to import any of the well-known types from a proto file
in another crate. To enable this I think we'll need to generate a function that
dependent crates can call to determine the directory that contains the
well-known types.

PiperOrigin-RevId: 706745114

rust/release_crates/BUILD

@@ -8,6 +8,7 @@ sh_binary(
         "//rust/release_crates/protobuf:protobuf_crate",
         "//rust/release_crates/protobuf_codegen:protobuf_codegen_crate",
         "//rust/release_crates/protobuf_example:protobuf_example_crate",
+        "//rust/release_crates/protobuf_well_known_types:crate",
         "//src/google/protobuf/compiler:protoc",
         "//upb_generator/minitable:protoc-gen-upb_minitable",
     ],

rust/release_crates/cargo_test.sh

@@ -40,15 +40,15 @@ mkdir $CRATE_ROOT
 PROTOBUF_TAR=$(rlocation com_google_protobuf/rust/release_crates/protobuf/protobuf_crate.tar)
 
 echo "Expanding protobuf crate tar"
-tar -xvf $PROTOBUF_TAR -C $CRATE_ROOT 
+tar -xvf $PROTOBUF_TAR -C $CRATE_ROOT
 
 CODEGEN_ROOT=$TMP_DIR/protobuf_codegen
 mkdir $CODEGEN_ROOT
 
 CODEGEN_TAR=$(rlocation com_google_protobuf/rust/release_crates/protobuf_codegen/protobuf_codegen_crate.tar)
 
-echo "Expanding protbuf_codegen crate tar"
-tar -xvf $CODEGEN_TAR -C $CODEGEN_ROOT 
+echo "Expanding protobuf_codegen crate tar"
+tar -xvf $CODEGEN_TAR -C $CODEGEN_ROOT
 
 EXAMPLE_ROOT=$TMP_DIR/protobuf_example
 mkdir $EXAMPLE_ROOT
@@ -58,6 +58,14 @@ EXAMPLE_TAR=$(rlocation com_google_protobuf/rust/release_crates/protobuf_example
 echo "Expanding protobuf_example crate tar"
 tar -xvf $EXAMPLE_TAR -C $EXAMPLE_ROOT
 
+WELL_KNOWN_TYPES_ROOT=$TMP_DIR/protobuf_well_known_types
+mkdir $WELL_KNOWN_TYPES_ROOT
+
+WELL_KNOWN_TYPES_TAR=$(rlocation com_google_protobuf/rust/release_crates/protobuf_well_known_types/crate.tar)
+
+echo "Expanding protobuf_well_known_types crate tar"
+tar -xvf $WELL_KNOWN_TYPES_TAR -C $WELL_KNOWN_TYPES_ROOT
+
 # Put the Bazel-built protoc and plugin at the beginning of $PATH
 PATH=$(dirname $(rlocation com_google_protobuf/protoc)):$PATH
 PATH=$(dirname $(rlocation com_google_protobuf/upb_generator/minitable/protoc-gen-upb_minitable)):$PATH
@@ -72,6 +80,10 @@ CARGO_HOME=$CARGO_HOME cargo publish --dry-run
 
 cd $EXAMPLE_ROOT
 CARGO_HOME=$CARGO_HOME cargo test
+
+cd $WELL_KNOWN_TYPES_ROOT
+CARGO_HOME=$CARGO_HOME cargo test
+
 # TODO: Cannot enable this dry-run yet because it checks that the versions of
 # its dependencies are published on crates.io, which they are definitely not
 # in this case.

rust/release_crates/protobuf_well_known_types/BUILD.bazel

@@ -0,0 +1,38 @@
+load("@rules_pkg//pkg:mappings.bzl", "pkg_files", "strip_prefix")
+load("@rules_pkg//pkg:tar.bzl", "pkg_tar")
+load("//:protobuf_version.bzl", "PROTOBUF_RUST_VERSION")
+
+pkg_tar(
+    name = "crate",
+    srcs = [
+        ":crate_root_files",
+        ":well_known_types",
+        "//:LICENSE",
+    ],
+    visibility = ["//rust:__subpackages__"],
+)
+
+pkg_files(
+    name = "crate_root_files",
+    srcs = [":srcs"],
+    strip_prefix = strip_prefix.from_root("rust/release_crates/protobuf_well_known_types"),
+)
+
+genrule(
+    name = "gen_cargo_toml",
+    srcs = ["Cargo-template.toml"],
+    outs = ["Cargo.toml"],
+    cmd = "cat $(SRCS) | sed -e 's/{{VERSION}}/{0}-beta/g' > $(OUTS)".format(PROTOBUF_RUST_VERSION),
+)
+
+filegroup(
+    name = "srcs",
+    srcs = [":gen_cargo_toml"] + glob(["**/*"]),
+    visibility = ["//rust:__subpackages__"],
+)
+
+pkg_files(
+    name = "well_known_types",
+    srcs = ["//src/google/protobuf:well_known_type_protos"],
+    prefix = "proto/google/protobuf",
+)

rust/release_crates/protobuf_well_known_types/Cargo-template.toml

@@ -0,0 +1,12 @@
+[package]
+name = "staging-protobuf-well-known-types"
+version = "{VERSION}"
+edition = "2021"
+description = "Protobuf Well-Known Types"
+license = "BSD-3-Clause"
+
+[dependencies]
+protobuf = { version = "{VERSION}", path = "../protobuf", package = "staging-protobuf" }
+
+[build-dependencies]
+protobuf-codegen = { version = "{VERSION}", path = "../protobuf_codegen", package = "staging-protobuf-codegen" }

rust/release_crates/protobuf_well_known_types/README.md

@@ -0,0 +1,2 @@
+This crate contains the protobuf
+[well-known types](https://protobuf.dev/reference/protobuf/google.protobuf/).

rust/release_crates/protobuf_well_known_types/build.rs

@@ -0,0 +1,20 @@
+use protobuf_codegen::CodeGen;
+
+fn main() {
+    CodeGen::new()
+        .inputs([
+            "google/protobuf/any.proto",
+            "google/protobuf/api.proto",
+            "google/protobuf/duration.proto",
+            "google/protobuf/empty.proto",
+            "google/protobuf/field_mask.proto",
+            "google/protobuf/source_context.proto",
+            "google/protobuf/struct.proto",
+            "google/protobuf/timestamp.proto",
+            "google/protobuf/type.proto",
+            "google/protobuf/wrappers.proto",
+        ])
+        .include("proto")
+        .generate_and_compile()
+        .unwrap();
+}

rust/release_crates/protobuf_well_known_types/src/lib.rs

@@ -0,0 +1 @@
+include!(concat!(env!("OUT_DIR"), "/protobuf_generated/google/protobuf/any.u.pb.rs"));

src/google/protobuf/compiler/rust/enum.cc

@@ -176,7 +176,7 @@ void GenerateEnumDefinition(Context& ctx, const EnumDescriptor& desc) {
                           }
                         }}},
                       R"rs(
-                fn constant_name(&self) -> Option<&'static str> {
+                fn constant_name(&self) -> $Option$<&'static str> {
                   #[allow(unreachable_patterns)] // In the case of aliases, just emit them all and let the first one match.
                   Some(match self.0 {
                     $name_cases$