Panic: reflect: Elem of invalid type

[abaruchi]

Hi,

I'm using the following versions:

• github.com/gogo/protobuf v1.3.2
• github.com/golang/protobuf v1.4.3
• go version 1.17.1
• macOS Catalina 10.15.7

The .proto file:

message ServiceAttestation {
  string field1 = 1;
  string field2 = 2;
}

message ServiceAttestationRequest {
    repeated ServiceAttestation request = 1 [(gogoproto.nullable) = false];
}

The request (PUT) to the service was a json like this:

{
    "request": [
        {
            "field1": "some_string",
            "field2": "aother_string"
        }
    ]
}

Panic message:

2022/06/06 14:57:13 http: panic serving [::1]:64968: reflect: Elem of invalid type packagepb.ServiceAttestation
goroutine 148 [running]:
net/http.(*conn).serve.func1()
        GOROOT/src/net/http/server.go:1802 +0xb9
panic({0x27de9c0, 0xc003abc760})
        GOROOT/src/runtime/panic.go:1047 +0x266
reflect.(*rtype).Elem(0xc00013a7e0)
        GOROOT/src/reflect/type.go:954 +0x134
google.golang.org/protobuf/internal/impl.(*messageConverter).New(0xc00149a6b0)
        external/org_golang_google_protobuf/internal/impl/convert.go:462 +0x29
google.golang.org/protobuf/internal/impl.(*listReflect).NewElement(0x2a360e0)
        external/org_golang_google_protobuf/internal/impl/convert_list.go:134 +0x22
github.com/golang/protobuf/jsonpb.(*Unmarshaler).unmarshalValue(0x286e820, {{}, 0x2a360e0, 0xc0035e9230, 0x7}, {0xc0001a61e0, 0xea, 0xf0}, {0x2f01c20, 0xc0009262a0})
        external/com_github_golang_protobuf/jsonpb/decode.go:402 +0x6ef
github.com/golang/protobuf/jsonpb.(*Unmarshaler).unmarshalMessage(0xc003ab62b8, {0x2ef11b0, 0xc003abc740}, {0xc00062a800, 0x0, 0x100})
        external/com_github_golang_protobuf/jsonpb/decode.go:339 +0x1c8c
github.com/golang/protobuf/jsonpb.(*Unmarshaler).UnmarshalNext(0xc000189180, 0x2a53ac0, {0xc79e7c0, 0xc003abee80})
        external/com_github_golang_protobuf/jsonpb/decode.go:127 +0x14e
github.com/grpc-ecosystem/grpc-gateway/runtime.decodeJSONPb(0xfd, {0x2a53ac0, 0xc003abee80})
        external/com_github_grpc_ecosystem_grpc_gateway/runtime/marshal_jsonpb.go:176 +0x70
github.com/grpc-ecosystem/grpc-gateway/runtime.DecoderWrapper.Decode({0xc79e7a0}, {0x2a53ac0, 0xc003abee80})
        external/com_github_grpc_ecosystem_grpc_gateway/runtime/marshal_jsonpb.go:149 +0x25
gitlab.gs.com/sre/sre/slo-repo/proto/manualattestation.local_request_ManualAttestationService_Insert_0({0x2ea34b0, 0xc0035e91a0}, {0x2ec1f60, 0xc0014920f0}, {0x2e96a08, 0xc001492180}, 0xc0035e4f00, 0x16)
        bazel-out/darwin-fastbuild-ST-3891b650e255/bin/proto/manualattestation/manualattestationpb_go_proto_/gitlab.gs.com/sre/sre/slo-repo/proto/manualattestation/manualattestation.pb.gw.go:61 +0x112
gitlab.gs.com/sre/sre/slo-repo/proto/manualattestation.RegisterManualAttestationServiceHandlerServer.func1({0x2e962e8, 0xc0009922a0}, 0xc0035e4f00, 0xc000191680)

Thanks,

[abaruchi]

Additional information:

When removing the gogoproto.nullable option (therefore, the struct created is a list of pointers []*somestruct) the code worked. I'm not sure, but looks like this nullabe option is hitting a bug.