Bump packaging to 22.0

[mgorny]

Could you please consider updating vendored packaging to 22.0, and either fixing setuptools to work with it or reporting issues upstream? We're unbundling dependencies in Gentoo and noticed setuptools isn't compatible with the new version:

  File "/tmp/portage/dev-python/setuptools-65.6.3/work/setuptools-65.6.3/./setuptools/msvc.py", line 24, in <module>
    from packaging.version import LegacyVersion
ImportError: cannot import name 'LegacyVersion' from 'packaging.version' (/usr/lib/pypy3.9/site-packages/packaging/version.py)

[mgorny]

Ok, maybe I'll give it a shot myself and make a PR if I succeed.

[mgorny]

Ok, this is going to be hard. @jaraco, @abravalheri FWICS the first problem is that packaging-22 removes LegacyVersion entirely. Do you think setuptools should ban non-PEP compliant versions at this point, or perhaps… inline LegacyVersion?

[mgorny]

Update: I think the only remaining blocker is that test_warn_accidental_env_marker_misconfig tests fail because the stray "env markers" now cause an exception in packaging. Not sure if we want to try to recover from it or just promote it from warning to an error.

[abravalheri]

I created a PR for that in #3790.

[jaraco]

The plan is to drop support for non-compliant versions. At one point, the deprecation was masked because Setuptools had vendored an older copy of packaging without the deprecation. I believe the deprecation has been in place for some time now, so it should be viable to drop support. I definitely am averse to supporting LegacyVersion. My preference at the time was that the packaging ecosystem should adopt Setuptools lenient versioning semantics, but we chose to go another direction, so Setuptools should follow and align.

[abravalheri]

Hi @jaraco, I am considering an update for packging==23.0 (#3790) in the next version of setuptools.

Please let me know if think we should hold back a little longer.

[jaraco]

No concerns.

[abravalheri]

This change probably has a dependence on #2822

[mgorny]

Oh, nice, I see @jaraco's already been working on it.