Allow string_type for Edition 2023.

PiperOrigin-RevId: 621050370

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

@@ -356,7 +356,6 @@ static bool IsEnumMapType(const FieldDescriptor& field) {
 absl::Status CppGenerator::ValidateFeatures(const FileDescriptor* file) const {
   absl::Status status = absl::OkStatus();
   auto edition = GetEdition(*file);
-  absl::string_view filename = file->name();
 
   google::protobuf::internal::VisitDescriptors(*file, [&](const FieldDescriptor& field) {
     const FeatureSet& resolved_features = GetResolvedSourceFeatures(field);
@@ -387,11 +386,7 @@ absl::Status CppGenerator::ValidateFeatures(const FileDescriptor* file) const {
     }
 
     if (unresolved_features.has_string_type()) {
-      if (!CanSkipEditionCheck(filename) && edition < Edition::EDITION_2024) {
-        status = absl::FailedPreconditionError(absl::StrCat(
-            "Field ", field.full_name(),
-            " specifies string_type which is not currently allowed."));
-      } else if (field.cpp_type() != FieldDescriptor::CPPTYPE_STRING) {
+      if (field.cpp_type() != FieldDescriptor::CPPTYPE_STRING) {
         status = absl::FailedPreconditionError(absl::StrCat(
             "Field ", field.full_name(),
             " specifies string_type, but is not a string nor bytes field."));

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

@@ -144,7 +144,7 @@ TEST_F(CppGeneratorTest, LegacyClosedEnumImplicit) {
       "Field Foo.bar has a closed enum type with implicit presence.");
 }
 
-TEST_F(CppGeneratorTest, NoStringTypeTillEdition2024) {
+TEST_F(CppGeneratorTest, AllowStringTypeForEdition2023) {
   CreateTempFile("foo.proto", R"schema(
     edition = "2023";
     import "google/protobuf/cpp_features.proto";
@@ -155,11 +155,28 @@ TEST_F(CppGeneratorTest, NoStringTypeTillEdition2024) {
     }
   )schema");
 
+  RunProtoc(
+      "protocol_compiler --proto_path=$tmpdir --cpp_out=$tmpdir foo.proto");
+
+  ExpectNoErrors();
+}
+
+TEST_F(CppGeneratorTest, ErrorsOnBothStringTypeAndCtype) {
+  CreateTempFile("foo.proto", R"schema(
+    edition = "2023";
+    import "google/protobuf/cpp_features.proto";
+
+    message Foo {
+      int32 bar = 1;
+      bytes baz = 2 [ctype = CORD, features.(pb.cpp).string_type = VIEW];
+    }
+  )schema");
+
   RunProtoc(
       "protocol_compiler --proto_path=$tmpdir --cpp_out=$tmpdir foo.proto");
 
   ExpectErrorSubstring(
-      "Field Foo.baz specifies string_type which is not currently allowed.");
+      "Foo.baz specifies both string_type and ctype which is not supported.");
 }
 
 TEST_F(CppGeneratorTest, StringTypeForCord) {