typing.get_type_hints fails when passed a class with PEP 695 type parameters and PEP 563 is enabled

[mjog]

Bug report

Bug description:

from __future__ import annotations

import typing

class Test[M]:
    attr: M

print(typing.get_type_hints(Test))

This fails with a NameError:

$ poetry run python3 pep_695_get_type_hints.py
Traceback (most recent call last):
  File "/home/mjog/pep_695_get_type_hints.py", line 8, in <module>
    print(typing.get_type_hints(Test))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/typing.py", line 2197, in get_type_hints
    value = _eval_type(value, base_globals, base_locals)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/typing.py", line 393, in _eval_type
    return t._evaluate(globalns, localns, recursive_guard)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/typing.py", line 900, in _evaluate
    eval(self.__forward_code__, globalns, localns),
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 1, in <module>
NameError: name 'M' is not defined

Although get_type_hints does not work with imported imported type aliases, this is not imported, so I would expect it to work. Further, the documentation for the function indicates using PEP 563 should /help/, but in this case it actually causes an error.

FWIW, removing the PEP 563 import works fine, giving:

{'attr': M}

Python version:

$ poetry run python3 --version
Python 3.12.0

CPython versions tested on:

3.12

Operating systems tested on:

Linux

Linked PRs

• gh-114053: Fix bad interaction of PEP-695, PEP-563 and get_type_hints #118009
• [3.12] gh-114053: Fix bad interaction of PEP-695, PEP-563 and get_type_hints (#118009) #118104
• gh-114053: Fix bad interaction of PEP 695, PEP 563 and inspect.get_annotations #120270
• gh-114053: Fix another edge case involving get_type_hints, PEP 695 and PEP 563 #120272
• [3.13] gh-114053: Fix bad interaction of PEP 695, PEP 563 and inspect.get_annotations (GH-120270) #120474
• [3.12] gh-114053: Fix bad interaction of PEP 695, PEP 563 and inspect.get_annotations (GH-120270) #120475
• [3.13] gh-114053: Fix another edge case involving get_type_hints, PEP 695 and PEP 563 (GH-120272) #121003
• [3.12] gh-114053: Fix another edge case involving get_type_hints, PEP 695 and PEP 563 (GH-120272) #121004

[mjog]

Sorry, my now-hidden comment above is incorrect - it does work fine with pre-695 generic classes, I just had a typo in the code.

This is only an issue with PEP 695 type parameters in conjunction with PEP 563.

[treykeown]

+1, just ran into this as well.

[AlexWaygood]

I suppose the problem is probably that get_type_hints looks things up in the global scope but doesn't look things up in the new annotation scopes introduced by PEP-695. The old way of defining TypeVars doesn't suffer from this because TypeVars were defined in the global scope; now they aren't.

[treykeown]

I created a temporary workaround based off the fix by @AlexWaygood if anyone needs a hack around this in the meantime: https://gist.github.com/treykeown/65c45b3da330d2293c7fb9d2a46520ed

[AlexWaygood]

The bug was fixed in typing.get_type_hints, but the same bug also exists in inspect.get_annotations when eval_str=True is passed:

Python 3.14.0a0 (heads/main:eeb8f67f837, Jun  6 2024, 12:03:13) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from __future__ import annotations
>>> class test[M]:
...     attr: M
...     
>>> import inspect
>>> inspect.get_annotations(test, eval_str=True)
Traceback (most recent call last):
  File "<python-input-4>", line 1, in <module>
    inspect.get_annotations(test, eval_str=True)
    ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
  File "/Users/alexw/dev/cpython/Lib/inspect.py", line 286, in get_annotations
    value if not isinstance(value, str) else eval(value, globals, locals)
                                             ~~~~^^^^^^^^^^^^^^^^^^^^^^^^
  File "<string>", line 1, in <module>
NameError: name 'M' is not defined