Internal changes

PiperOrigin-RevId: 541035586

src/google/protobuf/BUILD.bazel

@@ -398,8 +398,10 @@ cc_library(
         ":varint_shuffle",
         "//src/google/protobuf/io",
         "//src/google/protobuf/stubs:lite",
+        "@com_google_absl//absl/base",
         "@com_google_absl//absl/container:btree",
         "@com_google_absl//absl/container:flat_hash_set",
+        "@com_google_absl//absl/functional:any_invocable",
         "@com_google_absl//absl/hash",
         "@com_google_absl//absl/log:absl_check",
         "@com_google_absl//absl/log:absl_log",

src/google/protobuf/compiler/cpp/extension.cc

@@ -44,6 +44,13 @@ namespace google {
 namespace protobuf {
 namespace compiler {
 namespace cpp {
+namespace {
+
+bool RequiresLazyInitialization(const FieldDescriptor* descriptor) {
+  return false;
+}
+
+}  // namespace
 
 ExtensionGenerator::ExtensionGenerator(const FieldDescriptor* descriptor,
                                        const Options& options,
@@ -172,12 +179,20 @@ void ExtensionGenerator::GenerateDefinition(io::Printer* printer) {
         "#endif\n");
   }
 
-  format(
-      "PROTOBUF_ATTRIBUTE_INIT_PRIORITY2 "
-      "::$proto_ns$::internal::ExtensionIdentifier< $extendee$,\n"
-      "    ::$proto_ns$::internal::$type_traits$, $field_type$, $packed$>\n"
-      "  $scoped_name$($constant_name$, $1$, $verify_fn$);\n",
-      default_str);
+  if (RequiresLazyInitialization(descriptor_)) {
+    format(
+        "PROTOBUF_CONSTINIT PROTOBUF_ATTRIBUTE_INIT_PRIORITY2\n"
+        "::$proto_ns$::internal::ExtensionIdentifier< $extendee$,\n"
+        "    ::$proto_ns$::internal::$type_traits$, $field_type$, $packed$>\n"
+        "  $scoped_name$($constant_name$);\n");
+  } else {
+    format(
+        "PROTOBUF_ATTRIBUTE_INIT_PRIORITY2 "
+        "::$proto_ns$::internal::ExtensionIdentifier< $extendee$,\n"
+        "    ::$proto_ns$::internal::$type_traits$, $field_type$, $packed$>\n"
+        "  $scoped_name$($constant_name$, $1$, $verify_fn$);\n",
+        default_str);
+  }
 }
 
 }  // namespace cpp

src/google/protobuf/compiler/cpp/file.cc

@@ -1137,11 +1137,12 @@ void FileGenerator::GenerateReflectionInitializationCode(io::Printer* p) {
         }
       )cc");
 
-  // For descriptor.proto we want to avoid doing any dynamic initialization,
-  // because in some situations that would otherwise pull in a lot of
-  // unnecessary code that can't be stripped by --gc-sections. Descriptor
-  // initialization will still be performed lazily when it's needed.
-  if (file_->name() != "net/proto2/proto/descriptor.proto") {
+  // For descriptor.proto and cpp_features.proto we want to avoid doing any
+  // dynamic initialization, because in some situations that would otherwise
+  // pull in a lot of unnecessary code that can't be stripped by --gc-sections.
+  // Descriptor initialization will still be performed lazily when it's needed.
+  if (file_->name() != "net/proto2/proto/descriptor.proto"
+  ) {
     p->Emit({{"dummy", UniqueName("dynamic_init_dummy", file_, options_)}},
             R"cc(
               // Force running AddDescriptors() at dynamic initialization time.

src/google/protobuf/descriptor.cc

@@ -1964,10 +1964,11 @@ DescriptorPool* DescriptorPool::internal_generated_pool() {
 
 const DescriptorPool* DescriptorPool::generated_pool() {
   const DescriptorPool* pool = internal_generated_pool();
-  // Ensure that descriptor.proto gets registered in the generated pool. It is a
-  // special case because it is included in the full runtime. We have to avoid
-  // registering it pre-main, because we need to ensure that the linker
-  // --gc-sections step can strip out the full runtime if it is unused.
+  // Ensure that descriptor.proto and cpp_features.proto get registered in the
+  // generated pool. They're special cases because they're included in the full
+  // runtime. We have to avoid registering it pre-main, because we need to
+  // ensure that the linker --gc-sections step can strip out the full runtime if
+  // it is unused.
   DescriptorProto::descriptor();
   return pool;
 }

src/google/protobuf/extension_set.h

@@ -41,11 +41,14 @@
 #include <algorithm>
 #include <cassert>
 #include <string>
+#include <type_traits>
 #include <utility>
 #include <vector>
 
 #include "google/protobuf/stubs/common.h"
+#include "absl/base/call_once.h"
 #include "absl/container/btree_map.h"
+#include "absl/functional/any_invocable.h"
 #include "absl/log/absl_check.h"
 #include "google/protobuf/port.h"
 #include "google/protobuf/port.h"
@@ -1535,6 +1538,7 @@ class ExtensionIdentifier {
 extern PROTOBUF_ATTRIBUTE_WEAK ExtensionSet::LazyMessageExtension*
 MaybeCreateLazyExtension(Arena* arena);
 
+
 }  // namespace internal
 
 // Call this function to ensure that this extensions's reflection is linked into