fix: Ensure importlib_metadata runtime dependency installed with Python < 3.10

[jcfr]

Fixes a regression introduced in 5f068d5 ("chore(build): move to scikitbuild-core (#455)", 2024-03-01)

[jcfr]

cc: @mayeut @henryiii

[jcfr]

Thanks @agriyakhetarpal, @braindevices, @mloubout and @roastduck for the issue reports and pull requests 🙏

[jcfr]

Once the fix has been reviewed, approved and integrated, suggested path forward:

• Yank CMake 3.29.0
• Release 3.29.0.1

[mudit2812]

importlib_metadata is only needed for python 3.7. Versions 3.8 or greater can use importlib.metadata, which ships with python afaik

[mloubout]

Still needs to fix from #473 for correct version checking

[agriyakhetarpal]

@mudit2812 and @mloubout, Python 3.7 support was recently dropped with 3.29.0. Do we even need the conditional import for importlib_metadata at all, then? We can just use importlib.metadata and that should work? i.e., I don't think adding importlib_metadata as a required dependency is required at all, now – it would be better to drop the conditional import from src/cmake/__init__.py.

[mloubout]

Didn't see Python 3.8 was the minimum version now, should be able to completely drop importlib_metadata then as you pointed out.

[agriyakhetarpal]

docs/conf.py seems to have been using the correct Python version check, as reported by @mloubout:

cmake-python-distributions/docs/conf.py

Lines 20 to 25 in 85a457b

	if sys.version_info < (3, 8):
	import importlib_metadata as metadata
	else:
	from importlib import metadata

[henryiii]

Python 3.7 is the minimum version, not 3.8. We just dropped 2.7 and 3.6.

[agriyakhetarpal]

Oops, thanks! Updated my review to mark that change

[henryiii]

You are correct about this working in 3.8+ though, I just checked. There are bugs in importlib.metadata before 3.10.2, but this shouldn't hit those.

[henryiii]

@jcfr I don't have permission to yank cmake 3.29.0, let's go ahead and do that, since it's breaking people and people probably aren't requiring it yet after a few hours, and if they did, it would still work (due to yanks resolving if they can't resolve to a non-yanked version). CI will take ~20-30 mins here, then the release will take ~3 hours.

[jcfr]

re: yanked

[jcfr]

Thanks @henryiii for further tweaking the patch 🙏 and @mloubout for testing.

🚀 ✅

[mloubout]

Great, thanks for the quick resolution 🔥