Merge pull request #527 from haberman/fix-proto3-enum

Fix for proto2 files that use proto3 enums.

upb/def.c

@@ -1555,7 +1555,7 @@ static void make_layout(symtab_addctx* ctx, const upb_MessageDef* m) {
       field->submsg_index = sublayout_count++;
       subs[field->submsg_index].submsg = upb_FieldDef_MessageSubDef(f)->layout;
     } else if (upb_FieldDef_CType(f) == kUpb_CType_Enum &&
-               f->file->syntax == kUpb_Syntax_Proto2) {
+               f->sub.enumdef->file->syntax == kUpb_Syntax_Proto2) {
       field->submsg_index = sublayout_count++;
       subs[field->submsg_index].subenum = upb_FieldDef_EnumSubDef(f)->layout;
       UPB_ASSERT(subs[field->submsg_index].subenum);

upb/util/def_to_proto_regular_import_test.proto

@@ -30,3 +30,7 @@ syntax = "proto3";
 package pkg;
 
 message RegularImportMessage {}
+
+enum Proto3Enum {
+    PROTO3_ENUM_ZERO = 0;
+}

upb/util/def_to_proto_test.proto

@@ -50,6 +50,7 @@ message Message {
   }
   optional pkg.RegularImportMessage regular_import_message = 6;
   optional pkg.PublicImportMessage public_import_message = 7;
+  optional pkg.Proto3Enum proto3_enum = 8;
   extensions 1000 to max;
   extend Message {
     optional int32 ext = 1000;

upbc/protoc-gen-upb.cc

@@ -935,7 +935,8 @@ SubLayoutArray::SubLayoutArray(const protobuf::Descriptor* message) {
   std::vector<const protobuf::FieldDescriptor*> sorted_subenums =
       SortedSubEnums(message);
   for (const auto* field : sorted_subenums) {
-    if (field->file()->syntax() != protobuf::FileDescriptor::SYNTAX_PROTO2) {
+    if (field->enum_type()->file()->syntax() !=
+        protobuf::FileDescriptor::SYNTAX_PROTO2) {
       continue;
     }
     if (!indexes_.try_emplace(field->enum_type(), i).second) {
@@ -983,7 +984,8 @@ bool TryFillTableEntry(const protobuf::Descriptor* message,
       type = "b1";
       break;
     case protobuf::FieldDescriptor::TYPE_ENUM:
-      if (field->file()->syntax() == protobuf::FileDescriptor::SYNTAX_PROTO2) {
+      if (field->enum_type()->file()->syntax() ==
+          protobuf::FileDescriptor::SYNTAX_PROTO2) {
         // We don't have the means to test proto2 enum fields for valid values.
         return false;
       }