lfolger

This sounds reasonable to us. Could a prepare a contribution via gerrit following the steps outlined in https://github.com/protocolbuffers/protobuf-go/blob/master/CONTRIBUTING.md?

Could you clarify which version you are using? In the "What version of protobuf and what language are you using?" section you state that you are using [protov1](https://pkg.go.dev/github.com/golang/protobuf). However the...

In general, I like the feature. However, as we had issue in the past with consistency with the protobuf spec, we should make sure we align on the input format...

cc: @adonovan @timothy-king @findleyr

I might be missing something but is there a reason this needs to be part of the analysis.Pass at all? Is this to support files that are not part of...

>If types.Package provided this information that would be solution, but all existing creators of types.Package---that is, all clients of types.Checker, plus cmd/compiler + gcimporter, do not provide it. Maybe I...

Sorry I misread @timothy-king comment. It refers to packages.Package. I somehow read this as types.Package. Sorry for the confusion. I think a analysis only solution is appropriate here.

It is not entirely clear to me if TestOnly would be set to true for tests themselves. If so, it wouldn't work because tests might consist of test and non-test...

This would work for our use case.

Improving the error message seems reasonasble to use and we are happy to accept a contribution.