Non-exact stub file preventing mypyc modules from running

[rianhunter]

The class hierarchy in the _ctypes stub don't mirror the real module exactly. This doesn't prevent mypy from type-checking but it may prevent modules compiled with mypyc from running. Here is a test file

import _ctypes

class c_timespec(_ctypes.Structure):
    pass

Now if I try to import the built module:

$ python3
Python 3.11.2 (main, Mar 13 2023, 12:18:29) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import test
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "test.py", line 7, in <module>
    class c_win_timespec(ctypes.Structure):
AttributeError: module '_ctypes' has no attribute '_StructUnionBase'

This is because there is no _StructUnionBase in the real _ctypes module but there is one in the stub.

Who is at fault here? Is the stub file broken? Or does mypyc need to be extended to handle this case?

[rianhunter]

Note: I am happy to put all the effort into fixing this issue if someone can clarify what component is at fault here.