gh-125783: Add tests to prevent regressions with the combination of `ctypes` and metaclasses.

[junkmd]

I would like to backport this to 3.12 and 3.13 as well.

• Issue: gh-125783

[bedevere-app[bot]]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[ZeroIntensity]

This is an internal-only change, I don't think it needs a NEWS entry.

[junkmd]

comtypes has been using _pointer_type_cache since the first commit (an impressive 18 years ago!). https://github.com/enthought/comtypes/blob/938fbd50d2077c6bd524790a9ed798c3990cdfc0/comtypes/init.py#L230-L231

This was also discussed in #125783, and it seems that these implementations were made with careful consideration, as the originator of both comtypes and ctypes is the same person.

[encukou]

I plan to commit the suggestions and merge next week, if there are no objections.

[junkmd]

Can we apply needs backport to 3.12 and needs backport to 3.13 labels to this PR?

[ZeroIntensity]

I'm not sure if we backport increased test coverage.

[encukou]

We generally do, mostly to make it easier to backport later changes that need tests.

[miss-islington-app[bot]]

Thanks @junkmd for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.12, 3.13. 🐍🍒⛏🤖

[bedevere-app[bot]]

GH-125987 is a backport of this pull request to the 3.13 branch.

[bedevere-app[bot]]

GH-125988 is a backport of this pull request to the 3.12 branch.