[CI] Run tests on ARM

[moi15moi]

It might be a good idea to run the test on the windows-11-arm github action runner to catch potential issues that only occurs in that architecture.
I don't have an example for windows arm, but I had already had an issue that was only happening on linux arm cpu (due to using ctypes), so I believe we might catch some bugs.

[junkmd]

Thank you!
I think this is a really good suggestion.

Actually, I also haven’t encountered any specific issues on arm architecture yet, so I’m not entirely sure what might happen.
But precisely because of that, I believe it’s very important to try it early and identify any potential problems ahead of time.

It would be great if you could either create a draft pull request adding windows-11-arm to the workflow, or try it first in your fork and share the results — especially if you notice anything strange or unexpected.

If any tests fail or odd behavior appears, we can review it together and discuss with the community how to address it.

For the slow coverage issue with Python 3.12, we can probably handle it by adding conditional logic in the workflow if needed.

[moi15moi]

From what I can see, the unit tests fails on ARM.
To be exact, this test "seg fault".

It happen because addressof(ptr.contents) seems to access an invalid address.
If I comment self.assertEqual(addressof(ptr.contents), addressof(sc)) and and add addressof(ptr.contents), the test will still fail.
If I comment addressof(ptr.contents), the test will pass.

I believe it happen because comtypes.util.byref_at doesn't work properly, but i'm not sure what it does. It seems pretty complicated.

[junkmd]

Thank you for your investigation.

util.py has been left broken for a long time and was only recently revived, so such problems would occur.
This is an area involving many low-level details.

The followings are believed to be related to this problem:
python/cpython#136847
#445
python/cpython#130410
python/cpython#131747
python/cpython#133205

To address the problems you've reported, please try the following points:

1. Applying if sys.version_info >= (3, 14): _layout_ = "ms"

Currently, the util.PyCArgObject class has a _pack_ setting placed under a sys.version_info >= (3, 14) version bridge. However, starting from Python 3.14, using _pack_ is deprecated. The comment I added was probably a remnant from some trial-and-error session where adding _pack_ happened to make it work at the time.
In the Python versions and Windows environments currently supported by comtypes, this should work fine even without setting _pack_ at all. Instead, please try specifying the newly introduced _layout_ attribute.

2. Changing ("size", c_int) to ("size", c_ssize_t)

In CPython's implementation of PyCArgObject, the size field has been assigned Py_ssize_t since long ago.
On the other hand, when this project started (earlier than Python 3.2 and Python 2.7), c_ssize_t did not yet exist in ctypes, so c_int was likely used as a substitute. Please update it to the proper type.

[moi15moi]

I tried both suggestions on (3.11 to 3.14) and it still return an invalid adress.