I am seeing some unstable behavior when running

pants check ::

. Every now and then, mypy complains for multiple files that it cannot find torch and other packages:

path/to/file.py:1: error: Library stubs not installed for "PIL.Image"  [import-untyped]
path/to/file.py:1: error: Cannot find implementation or library stub for module named "torch"  [import-not-found]
path/to/file.py:1: error: Cannot find implementation or library stub for module named "torch.distributed.distributed_c10d"  [import-not-found]
path/to/file.py:1: error: Cannot find implementation or library stub for module named "torch.nn"  [import-not-found]

The error always gets reported for line

1

and on multiple files at the same time. Just running

pants check ::

again makes it go away. So it’s not reproducible reliably but also not just a one-time thing. Some days happens, some days not. Has anyone seen this before?

Sounds similar to https://github.com/pantsbuild/pants/issues/18519 / https://github.com/python/mypy/issues/17049 Are you on mypy >= 1.10.1 ?

Oh yes, the first link looks very related, thanks.

hmm, I have also had some reports internally that suggest the upstream mypy fix is not working. I have not been able to debug further. Disabling the incremental cache would still be the work around.