gh-104533: Fix @ctypes.util.struct with string annotations

[vstinner]

Fix @ctypes.util.struct on structures declared in a module which uses from __future__ import annotations. The decorator now calls get_annotations() with eval_str=True.

• Issue: Annotation-based syntax for ctypes structs #104533

[vstinner]

With this change, the following example:

from ctypes.util import struct

@struct
class Point:
    x: 'invalid_name'

now fails with NameError:

Traceback (most recent call last):
  File "/home/vstinner/python/main/ann.py", line 3, in <module>
    @struct
     ^^^^^^
  File "/home/vstinner/python/main/Lib/ctypes/util.py", line 576, in struct
    return process_the_struct(class_or_none)
  File "/home/vstinner/python/main/Lib/ctypes/util.py", line 515, in _process_struct
    annotations = annotationlib.get_annotations(decorated_class, eval_str=True)
  File "/home/vstinner/python/main/Lib/annotationlib.py", line 1078, in get_annotations
    else eval(_rewrite_star_unpack(value), globals, locals)
         ~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 1, in <module>
NameError: name 'invalid_name' is not defined

The traceback starts on line 3 of ann.py, which is where the bug occurs: the traceback is correct and useful.

[vstinner]

This line should be updated if PR gh-154038 is merged first.

[vstinner]

Crap. I missed my own comment when I merged this PR, and now the pre-commit CI fails on the main branch :-( I wrote #154091 to fix the CI.

[vstinner]

cc @ZeroIntensity

[vstinner]

I found this bug while trying to convert ctypes.Structure structures to @ctypes.util.struct in Lib/_pyrepl/windows_console.py which uses from __future__ import annotations.

[vstinner]

@ctypes.util.wrap_dll_function() has the same bug: see PR gh-154042 which fixes it.