Protobuf repeated uint, fixed and enum serialization not working

[Dogacel]

Describe the bug

Any field in the following message is not being able to serialize:

syntax = "proto3";

package repeateds;

message RepeatedsMessage {
  repeated uint32 repeated_uint32 = 3;
  repeated uint64 repeated_uint64 = 4;
  repeated fixed32 repeated_fixed32 = 7;
  repeated fixed64 repeated_fixed64 = 8;
  repeated sfixed32 repeated_sfixed32 = 9;
  repeated sfixed64 repeated_sfixed64 = 10;

  repeated NestedEnum repeated_nested_enum = 18;
  repeated ForeignEnum repeated_foreign_enum = 19;

  enum NestedEnum {
    FOO = 0;
    BAR = 1;
    BAZ = 2;
    NEG = -1;  // Intentionally negative.
  }
}

enum ForeignEnum {
  FOREIGN_FOO = 0;
  FOREIGN_BAR = 1;
  FOREIGN_BAZ = 2;
}

I think the documentation has some conflicting into, according to my tests uints and sfixed's work fine.

I just added SIGNED to sfixed and it turned out OK. But when it comes to repeated values, I think just writing

  @ProtoNumber(number = 5)
  @ProtoPacked
  @ProtoType(type = SIGNED)
  public val repeatedSint32: List<Int> = emptyList(),

does not work. I haven't tested Map completely yet but I think there is gonna be a similar issue there too.

To Reproduce

As I am running conformance tests from my public project and it contains lots of lines, here is the link to tests, you can find every offender in tests as commented in source code.

Link to project tests

Expected behavior

All types should serialize / deserialize correctly.

Environment

• Kotlin version: 1.9.0
• Library version: 1.9.0
• Kotlin platforms: JVM
• Gradle version: 7

[sandwwraith]

I guess it's because

@ProtoType(type = SIGNED)
public val repeatedSint32: List<Int> = emptyList()

makes @prototype applied to List and not Int. Correct way to use it would be val repeatedSint32: List<@ProtoType(SIGNED) Int> = emptyList(), but current annotations target make it impossible.

[Dogacel]

I guess it's because

@ProtoType(type = SIGNED)
public val repeatedSint32: List<Int> = emptyList()

makes @prototype applied to List and not Int. Correct way to use it would be val repeatedSint32: List<@ProtoType(SIGNED) Int> = emptyList(), but current annotations target make it impossible.

OK it makes sense, but it seems like that @ProtoType is just ignored when used against a List according to my tests.

For UintXX and Enum repeateds, I see this error for some reason.

Expected wire type 0, but found 2

I think sint is deserialized but incorrectly due to format (value = 2*value + 1).

Is there anything I can do to help? What is the preferred way to fix this? Maybe we can create a custom serializer for those types temporarily?

[sandwwraith]

I'm not sure custom serializer would help, because it doesn't have a place to pass @ProtoType annotation. It should be fixed in the runtime somehow.

[Dogacel]

I'm not sure custom serializer would help, because it doesn't have a place to pass @ProtoType annotation. It should be fixed in the runtime somehow.

I don't have much context on how to resolve those issues but I am able to successfully reproduce them so I opened a PR here:

• Add protobuf conformance tests v1 #2404

This PR should include a very extensive test suite that can be run. I hope solutions to the bugs can be written on top of this suite so we can verify them as they are fixed.

I also think having those conformance tests is a great way to track the completeness and maturity of the library. What are your thoughts @sandwwraith ? I am hoping that this is useful.

[Dogacel]

I opened three sub issues, closing this one

• Protobuf - uintXX packed array can't be serialized / deserialized #2418
• Protobuf - sintXX, fixedXX and sfixedXX array can't be serialized / deserialized #2419
• Protobuf - sintXX, fixedXX and sfixedXX map keys and values not serialized / deserialized correctly. #2417