Ambiguous import paths with mypy 0.780?

[roitk]

Hi!

We currently use mypy-protobuf in a typechecking CI step for buildgrid. With the release of mypy 0.780, we began to see the following error in the CI.

buildgrid/_protos/build/bazel/semver/semver_pb2.pyi: error: Source file found twice under different module names: 'buildgrid._protos.build.bazel.semver.semver_pb2' and 'build.bazel.semver.semver_pb2'
Found 1 error in 1 file (checked 144 source files)

We tried regenerating the .pyi files with the newer version of mypy, but the issue persisted, so we've had to roll back our mypy version.

Some additional information:

• We noticed that the new version of mypy shipped with a change in its import following logic. The blogpost says this was for the mypy daemon, but perhaps it's relevant for the CLI tool as well?
• Our mypy.ini. Notably, buildgrid/_protos is in the import path.
• Our type-checking CI step is pretty simple; it just installs some dependencies and runs mypy on the main source folder: https://gitlab.com/BuildGrid/buildgrid/-/blob/master/.gitlab-ci.yml#L62-63

I'm not sure if this is an issue with mypy, mypy-protobuf, or our configuration, so please let us know if we should post this elsewhere!

[roitk]

It looks like another user has run into this problem, so this may not be caused by mypy-protobuf. python/mypy#8944