Collect extensions with the descriptor pool where the file descriptor…

… was built from, instead of with the generated pool.

PiperOrigin-RevId: 705635053

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

@@ -102,44 +102,34 @@ bool CollectExtensions(const Message& message, FieldDescriptorSet* extensions) {
   return true;
 }
 
-// Finds all extensions in the given message and its sub-messages.  If the
-// message contains unknown fields (which could be extensions), then those
-// extensions are defined in alternate_pool.
-// The message will be converted to a DynamicMessage backed by alternate_pool
-// in order to handle this case.
-void CollectExtensions(const FileDescriptorProto& file_proto,
-                       const DescriptorPool& alternate_pool,
-                       FieldDescriptorSet* extensions,
-                       const std::string& file_data) {
-  if (!CollectExtensions(file_proto, extensions)) {
-    // There are unknown fields in the file_proto, which are probably
-    // extensions. We need to parse the data into a dynamic message based on the
-    // builder-pool to find out all extensions.
-    const Descriptor* file_proto_desc = alternate_pool.FindMessageTypeByName(
-        file_proto.GetDescriptor()->full_name());
-    ABSL_CHECK(file_proto_desc)
-        << "Find unknown fields in FileDescriptorProto when building "
-        << file_proto.name()
-        << ". It's likely that those fields are custom options, however, "
-           "descriptor.proto is not in the transitive dependencies. "
-           "This normally should not happen. Please report a bug.";
-    DynamicMessageFactory factory;
-    std::unique_ptr<Message> dynamic_file_proto(
-        factory.GetPrototype(file_proto_desc)->New());
-    ABSL_CHECK(dynamic_file_proto.get() != nullptr);
-    ABSL_CHECK(dynamic_file_proto->ParseFromString(file_data));
-
-    // Collect the extensions again from the dynamic message. There should be no
-    // more unknown fields this time, i.e. all the custom options should be
-    // parsed as extensions now.
-    extensions->clear();
-    ABSL_CHECK(CollectExtensions(*dynamic_file_proto, extensions))
-        << "Find unknown fields in FileDescriptorProto when building "
-        << file_proto.name()
-        << ". It's likely that those fields are custom options, however, "
-           "those options cannot be recognized in the builder pool. "
-           "This normally should not happen. Please report a bug.";
-  }
+// Finds all extensions for custom options in the given file descriptor with the
+// builder pool which resolves Java features instead of the generated pool.
+void CollectExtensions(const FileDescriptor& file,
+                       FieldDescriptorSet* extensions) {
+  FileDescriptorProto file_proto = StripSourceRetentionOptions(file);
+  std::string file_data;
+  file_proto.SerializeToString(&file_data);
+  const Descriptor* file_proto_desc = file.pool()->FindMessageTypeByName(
+      file_proto.GetDescriptor()->full_name());
+
+  // descriptor.proto is not found in the builder pool, meaning there are no
+  // custom options.
+  if (file_proto_desc == nullptr) return;
+
+  DynamicMessageFactory factory;
+  std::unique_ptr<Message> dynamic_file_proto(
+      factory.GetPrototype(file_proto_desc)->New());
+  ABSL_CHECK(dynamic_file_proto.get() != nullptr);
+  ABSL_CHECK(dynamic_file_proto->ParseFromString(file_data));
+
+  // Collect the extensions again from the dynamic message.
+  extensions->clear();
+  ABSL_CHECK(CollectExtensions(*dynamic_file_proto, extensions))
+      << "Found unknown fields in FileDescriptorProto when building "
+      << file_proto.name()
+      << ". It's likely that those fields are custom options, however, "
+         "those options cannot be recognized in the builder pool. "
+         "This normally should not happen. Please report a bug.";
 }
 
 // Our static initialization methods can become very, very large.
@@ -474,11 +464,8 @@ void FileGenerator::GenerateDescriptorInitializationCodeForImmutable(
   // To find those extensions, we need to parse the data into a dynamic message
   // of the FileDescriptor based on the builder-pool, then we can use
   // reflections to find all extension fields
-  FileDescriptorProto file_proto = StripSourceRetentionOptions(*file_);
-  std::string file_data;
-  file_proto.SerializeToString(&file_data);
   FieldDescriptorSet extensions;
-  CollectExtensions(file_proto, *file_->pool(), &extensions, file_data);
+  CollectExtensions(*file_, &extensions);
 
   if (options_.strip_nonfunctional_codegen) {
     // Skip feature extensions, which are a visible (but non-functional)