mypy 0.990 shows no errors when passing source directory as absolute path

[intgr]

Bug Report

I noticed that after upgrading to 0.990, mypy in djangorestframework-stubs CI no longer finds any errors.

It seems this happens when the source folder is passed as a full path, instead of relative path. $PWD is the full path of the current working directory:

% mypy --config-file $PWD/mypy.ini --show-traceback --hide-error-context ./drf_source/tests |tail -n1
Found 569 errors in 48 files (checked 83 source files)
% mypy --config-file $PWD/mypy.ini --show-traceback --hide-error-context $PWD/drf_source/tests |tail -n1
Success: no issues found in 83 source files

Maybe, just maybe, this is related to #13768? EDIT: seems not to be, various --follow-imports= options have no effect.

To Reproduce

1. Check out https://github.com/intgr/djangorestframework-stubs branch update-to-mypy-0.990
2. Install dependencies from requirements.txt in a virtualenv
3. Upgrade to mypy 0.990
4. Run python scripts/typecheck_tests.py, which populates the drf_source directory
5. Try running the commands above

Your Environment

• Mypy version used: 0.990
• Mypy configuration options from mypy.ini (and other config files): https://github.com/typeddjango/djangorestframework-stubs/blob/06a2f2f9f6c05a07f03bc1bd7f1b54ecfd7a3c43/mypy.ini
• Python version used: 3.10.8

[intgr]

I can also reproduce this when I comment out mypy plugins in mypy.ini

[intgr]

Also reproduced this in another project of mine.

[hauntsaninja]

Does it reproduce with --no-namespace-packages?

[intgr]

Yes. Adding --no-namespace-packages does not solve the issue, still getting "no issues found".

[ilevkivskyi]

Also do you have $PWD in your PYTHONPATH maybe? What was the last mypy version that didn't have this issue? Around 0.970 mypy started interpreting everything in PYTHONPATH as third party packages and silencing them. You can try --no-silence-site-packages

[intgr]

This issue does not occur with 0.982

% mypy --version
mypy 0.982 (compiled: yes)
% mypy --config-file $PWD/mypy.ini --show-traceback --hide-error-context --no-namespace-packages $PWD/drf_source/tests |tail -n1
.../djangorestframework-stubs/mypy.ini: [mypy]: disable_error_code: Invalid error code(s): empty-body
Found 575 errors in 49 files (checked 83 source files)

PYTHONPATH is unset in the shell I'm testing this from. The typecheck_tests.py script does indeed add $PWD to PYTHONPATH, but it doesn't seem to affect this issue.

[ilevkivskyi]

Hm, probably the easiest way is to bisect mypy commits. Since the problem looks really bizzare.

[intgr]

Adding --no-silence-site-packages with mypy 0.990 and using $PWD only mostly prints errors from site-packages modules, not the project itself.

Are you unable to reproduce this in any of your own projects?

I can give bisecting a try.

[ilevkivskyi]

Are you unable to reproduce this in any of your own projects?

No, but I also don't have many.

I can give bisecting a try.

That would be great, since I will not have much time today/tomorrow.

[intgr]

Git bisected it to:

00ca6bf is the first bad commit

Which is #13768 as I initially suspected.

[ilevkivskyi]

@JukkaL could you please take a look?

[intgr]

I was wrong before. --no-silence-site-packages does have an effect on the output but it's really weird.

• mypy --no-silence-site-packages $PWD/drf_source/tests 142 errors in 18 files (checked 83 source files) -- most of these are site-pacakges errors, but 6 are from project itself!
• mypy --no-silence-site-packages ./drf_source/tests 142 errors in 18 files (checked 83 source files), same as above
• mypy $PWD/drf_source/tests no issues found in 83 source files
• mypy ./drf_source/tests 569 errors in 48 files (checked 83 source files) -- expected behavior