Python 3.11 ModuleNotFoundError: No module named 'tomllib'

[PerchunPak]

Describe the bug

In Python 3.11 it is raising exception with ModuleNotFoundError.

To Reproduce

Install Python 3.11

$ black .

The resulting error is:

Traceback (most recent call last):
  File "/home/runner/work/autodonate/autodonate/.venv/bin/black", line 5, in <module>
    from black import patched_main
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/work/autodonate/autodonate/.venv/lib/python3.11/site-packages/black/__init__.py", line 52, in <module>
    from black.files import (
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/runner/work/autodonate/autodonate/.venv/lib/python3.11/site-packages/black/files.py", line 25, in <module>
    import tomllib
    ^^^^^^^^^^^^^^
ModuleNotFoundError: No module named 'tomllib'

Environment

• Black's version: 22.3.0
• OS and Python version: Github Actions Ubuntu, Python 3.11

Additional context

Logs from my CI.
Also, why you haven't did any CI on 3.11?

[JelleZijlstra]

Python 3.11 is still in alpha. The released version will have tomllib available, but whatever alpha version you're running might not have it yet. We'll run 3.11 in CI once we're closer to the release date for 3.11.

[ichard26]

I will also note that I have tried testing 3.11-dev in GHA CI, but last time I tried our dependencies weren't 3.11 ready: 0505c8f and https://github.com/psf/black/runs/5504048923?check_suite_focus=true

I did actually schedule a reminder to try again when the first beta comes out, but I'd be open to trying again soon.

[SamuelMarks]

Also this did work on 3.11.0-alpha.5 with black-22.1.0-py3-none-any.whl just not 3.11.0-alpha.6 with black-22.3.0-py3-none-any.whl.

[pawamoy]

Would it be possible to change to a try/except (and put back tomli as dep without marker) instead of a condition on the Python version, at least until tomllib is available in Python 3.11 (alpha or not)? I understand 3.11 is still alpha, but I believe many users want to test their code and run their CI tools (i.e. Black) on Python 3.11. Of course I can pin Black to <22.3 for Python 3.11 only (with markers), but that's a bit cumbersome to do in every project 😕

[JelleZijlstra]

@pawamoy that's fair, opened #2987