Type-check on all Python versions

[Avasam]

Summary of changes

Actually type-check targeting all Python versions in CI, including 3.12 & 3.13
This is important validation for #2345

I'd rather if it was possible for the CI to tell mypy which python version to target to override python_version config.

Pull Request Checklist

• Changes have tests (these are the test changes)
• News fragment added in newsfragments/. (not public-facing)
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[Avasam]

Alternatively:

Suggested change

	# Can't disable on the exact line because distutils doesn't exists on Python 3.12
	# and mypy isn't aware of distutils_hack, causing distutils.core.Command to be Any,
	# and a [unused-ignore] to be raised on 3.12+
	# See comment in mypy.ini about distutils on Python 3.12

[Avasam]

Would love if there was a way to tell the CI to pass the --python-version argument to override this config so that IDEs and maybe default local runs can test against the oldest supported Python version.

[abravalheri]

pytest-mypy mentions the following:

Mypy supports reading configuration settings from a mypy.ini file. Alternatively, the plugin can be configured in a conftest.py to invoke mypy with extra options:

def pytest_configure(config):
    plugin = config.pluginmanager.getplugin('mypy')
    plugin.mypy_argv.append('--check-untyped-defs')

Not sure if that is useful to achieve what you want via conftest.py.

[Avasam]

I think it would, something like:

import sys

def pytest_configure(config):
    plugin = config.pluginmanager.getplugin('mypy')
    plugin.mypy_argv.append(f'--python-version={sys.version_info.major}.{sys.version_info.minor}')

Since you approved, mind if I tackle your comments in a follow-up ?

[abravalheri]

Since you approved, mind if I tackle your comments in a follow-up ?

Sure!

---

plugin.mypy_argv.append(f'--python-version={sys.version_info.major}.{sys.version_info.minor}')

Is that going to behave differently than just omitting python_version in mypy.ini?

pytest-mypy would force the contributor to check on the current version anyway, right?

[Avasam]

Honestly, I never run pytest-mypy locally. But yes that would mean that the mypy-test commands would always check for the executed Python. A more complete snippet of code would probably check if this is being run on the CI (check for GitHub env var) and whether the dev already passed --python-version as to not overwrite it (let's say they run pytest-mypy directly w/o tox)

[Avasam]

This includes potentially moving _distutils to a path where the last folder ends in distutils so it can be added to the MYPY_PATH. (although that only helps setuptool's own development, not its downstream Python 3.12+ users)

Or typeshed accepting to publish a non-stdlib types-distutils

Until then, Python 3.12+ users won't be able to have complete typing without types-setuptools (which already provides distutils-stubs https://github.com/python/typeshed/tree/main/stubs/setuptools/distutils) since anything inheriting or re-exported from distutils will be typed as Any.

Anyway, not a huge concern just yet, but something to start thinking about.

[Avasam]

python/typeshed@ac8720b#diff-d648cd8f6aa0211e1f3e96439ba4a67ec8b7474fbf0aba2459b894cb5022a0bcR16

[abravalheri]

pytest-mypy mentions the following:

Mypy supports reading configuration settings from a mypy.ini file. Alternatively, the plugin can be configured in a conftest.py to invoke mypy with extra options:

def pytest_configure(config):
    plugin = config.pluginmanager.getplugin('mypy')
    plugin.mypy_argv.append('--check-untyped-defs')

Not sure if that is useful to achieve what you want via conftest.py.

[abravalheri]

I think this one we can do:

Suggested change

	_Distribution: TypeAlias = distutils.core.Distribution
	from distutils.core import Distribution as _Distribution

and remove the import for TypeAlias.

(errors.py should be fine using the TypeAlias though - I am indifferent on the approach for that file).

[Avasam]

Since you already approved and these are changed in #4504 , I'll keep it as-is for this PR

[abravalheri]

Suggested change

	_Extension: TypeAlias = distutils.core.Extension
	from distutils.core import Extension as _Extension

And then we can drop the TypeAlias.

[abravalheri]

Thank you very much, @Avasam.