question: any way to prevent copying lock fields in proto comparison?

[OliverCardoza]

I'm comparing protos from the github.com/google/fhir library. For example:
https://raw.githubusercontent.com/google/fhir/master/go/proto/google/fhir/proto/r4/core/datatypes_go_proto/datatypes.pb.go

These protos include a MessageState field with the DoNotCopy pragma (context).

I have unit test code comparing protos similar to the following:

import (
  "testing"

  dtpb "github.com/google/fhir/go/proto/google/fhir/proto/r4/core/datatypes_go_proto"
  "github.com/google/go-cmp/cmp"
  "google.golang.org/protobuf/testing/protocmp"
)

func TestMyFunc(t *testing.T) {
  expected := &dtpb.DateTime{...}
  actual := MyFunc(inputs...)
  if diff := cmp.Diff(*expected, *actual, protocmp.Transform()); diff != "" {
    t.Errorf("unexpected proto diff:\n%v", diff)
  } 
}

This builds and tests successfully but go vet complains:

[$CALLSITE] call of cmp.Diff copies lock value:
github.com/google/fhir/go/proto/google/fhir/proto/r4/core/datatypes_go_proto.DateTime
contains google.golang.org/protobuf/internal/impl.MessageState contains sync.Mutex

I've tried adding ignore/filter options to cmp.Diff but it appears that the copy may always occur and ignore just silences the field/message diff in the output.

I feel like I'm missing something. Any tips appreciated!

[dsnet]

Hi, I suspect that the problem is to pass the reference to the protobuf, rather than a shallow copy of it:

- if diff := cmp.Diff(*expected, *actual, protocmp.Transform()); diff != "" {
+ if diff := cmp.Diff(expected, actual, protocmp.Transform()); diff != "" {

[OliverCardoza]

🤦‍♂️ I did not make the connection that pointer dereferencing creates shallow copies. thank you!