Fix cord extension check to apply to all editions.

This was mistakenly gated on edition and only applied to proto2/proto3 and edition 2023.

This also cleans up some of our validation logic for ctype/string_type.  Similar to other language features, ctype will only be validated by the C++ generator.  This means that protos that aren't used in C++ may end up with ctype incorrectly specified, but our Prototiller transformation for 2024 will strip those anyway (since we ban ctype in 2024).

PiperOrigin-RevId: 676893004

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

@@ -355,8 +355,6 @@ static bool IsEnumMapType(const FieldDescriptor& field) {
 
 absl::Status CppGenerator::ValidateFeatures(const FileDescriptor* file) const {
   absl::Status status = absl::OkStatus();
-  auto edition = GetEdition(*file);
-
   google::protobuf::internal::VisitDescriptors(*file, [&](const FieldDescriptor& field) {
     const FeatureSet& resolved_features = GetResolvedSourceFeatures(field);
     const pb::CppFeatures& unresolved_features =
@@ -413,8 +411,7 @@ absl::Status CppGenerator::ValidateFeatures(const FileDescriptor* file) const {
       }
     }
 
-    // 'ctype' check has moved to DescriptorBuilder for Edition 2023 and above.
-    if (edition < Edition::EDITION_2023 && field.options().has_ctype()) {
+    if (field.options().has_ctype()) {
       if (field.cpp_type() != FieldDescriptor::CPPTYPE_STRING) {
         status = absl::FailedPreconditionError(absl::StrCat(
             "Field ", field.full_name(),
@@ -424,10 +421,18 @@ absl::Status CppGenerator::ValidateFeatures(const FileDescriptor* file) const {
         if (field.is_extension()) {
           status = absl::FailedPreconditionError(absl::StrCat(
               "Extension ", field.full_name(),
-              " specifies ctype=CORD which is not supported for extensions."));
+              " specifies Cord type which is not supported for extensions."));
         }
       }
     }
+
+    if (field.cpp_type() == FieldDescriptor::CPPTYPE_STRING &&
+        field.cpp_string_type() == FieldDescriptor::CppStringType::kCord &&
+        field.is_extension()) {
+      status = absl::FailedPreconditionError(absl::StrCat(
+          "Extension ", field.full_name(),
+          " specifies Cord type which is not supported for extensions."));
+    }
   });
   return status;
 }

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

@@ -255,10 +255,31 @@ TEST_F(CppGeneratorTest, StringTypeCordNotForExtension) {
       "--experimental_editions foo.proto");
 
   ExpectErrorSubstring(
-      "Extension bar specifies string_type=CORD which is not supported for "
+      "Extension bar specifies Cord type which is not supported for "
       "extensions.");
 }
 
+TEST_F(CppGeneratorTest, InheritedStringTypeCordNotForExtension) {
+  CreateTempFile("foo.proto", R"schema(
+    edition = "2024";
+    import "google/protobuf/cpp_features.proto";
+    option features.(pb.cpp).string_type = CORD;
+
+    message Foo {
+      extensions 1 to max;
+    }
+    extend Foo {
+      bytes bar = 1;
+    }
+  )schema");
+
+  RunProtoc(
+      "protocol_compiler --proto_path=$tmpdir --cpp_out=$tmpdir "
+      "--experimental_editions foo.proto");
+
+  ExpectNoErrors();
+}
+
 TEST_F(CppGeneratorTest, CtypeOnNoneStringFieldTest) {
   CreateTempFile("foo.proto",
                  R"schema(
@@ -286,7 +307,7 @@ TEST_F(CppGeneratorTest, CtypeOnExtensionTest) {
   RunProtoc(
       "protocol_compiler --proto_path=$tmpdir --cpp_out=$tmpdir foo.proto");
   ExpectErrorSubstring(
-      "Extension bar specifies ctype=CORD which is "
+      "Extension bar specifies Cord type which is "
       "not supported for extensions.");
 }
 }  // namespace

src/google/protobuf/descriptor.cc

@@ -7952,32 +7952,6 @@ void DescriptorBuilder::ValidateOptions(const FieldDescriptor* field,
 
   ValidateFieldFeatures(field, proto);
 
-  auto edition = field->file()->edition();
-  auto& field_options = field->options();
-
-  if (field_options.has_ctype()) {
-    if (edition == Edition::EDITION_2023) {
-      if (field->cpp_type() != FieldDescriptor::CPPTYPE_STRING) {
-        AddError(field->full_name(), proto,
-                 DescriptorPool::ErrorCollector::TYPE,
-                 absl::StrFormat("Field %s specifies ctype, but is not a "
-                                 "string nor bytes field.",
-                                 field->full_name())
-                     .c_str());
-      }
-      if (field_options.ctype() == FieldOptions::CORD) {
-        if (field->is_extension()) {
-          AddError(field->full_name(), proto,
-                   DescriptorPool::ErrorCollector::TYPE,
-                   absl::StrFormat("Extension %s specifies ctype=CORD which is "
-                                   "not supported for extensions.",
-                                   field->full_name())
-                       .c_str());
-        }
-      }
-    }
-  }
-
   // Only message type fields may be lazy.
   if (field->options().lazy() || field->options().unverified_lazy()) {
     if (field->type() != FieldDescriptor::TYPE_MESSAGE) {

src/google/protobuf/descriptor_unittest.cc

@@ -2957,29 +2957,6 @@ TEST_F(MiscTest, DefaultValues) {
   EXPECT_EQ(enum_value_a, message->field(22)->default_value_enum());
 }
 
-TEST_F(MiscTest, InvalidFieldOptions) {
-  FileDescriptorProto file_proto;
-  file_proto.set_name("foo.proto");
-
-  file_proto.set_syntax("editions");
-  file_proto.set_edition(Edition::EDITION_2023);
-
-  DescriptorProto* message_proto = AddMessage(&file_proto, "TestMessage");
-  AddField(message_proto, "foo", 1, FieldDescriptorProto::LABEL_OPTIONAL,
-           FieldDescriptorProto::TYPE_INT32);
-  FieldDescriptorProto* bar_proto =
-      AddField(message_proto, "bar", 2, FieldDescriptorProto::LABEL_OPTIONAL,
-               FieldDescriptorProto::TYPE_INT32);
-
-  FieldOptions* options = bar_proto->mutable_options();
-  options->set_ctype(FieldOptions::CORD);
-
-  // Expects it to fail as int32 fields cannot have ctype.
-  DescriptorPool pool;
-  const FileDescriptor* file = pool.BuildFile(file_proto);
-  EXPECT_EQ(file, nullptr);
-}
-
 TEST_F(MiscTest, FieldOptions) {
   // Try setting field options.