functools.wraps does not work on class methods

We recently hit an error using @wraps on a class method in Trio: https://github.com/python-trio/trio/issues/2775#issuecomment-1702892474 when checked with pyright. It works fine on mypy, but I'm guessing they might be special-casing wraps usage while pyright doesn't.

Minimal repro (python 3.11):

from functools import wraps
from typing import assert_type


def foo(param: int) -> str:
    """docstring"""
    return ""

@wraps(foo)
def my_function(blah: int) -> str:
    return 'foo'

# works fine
assert_type(my_function(5), str)

class MyOtherClass:
    def bar(self, param: int) -> str:
        """docstring"""
        return ""

class MyClass:
    @wraps(MyOtherClass.bar)
    def my_method(self, blah: int) -> str:
        return 'foo'

instance = MyClass()
# works in mypy, but not pyright
assert_type(instance.my_method(5), str)

mypy 1.5.1 works without any issue, pyright 1.1.325 gives

./test.py
  ./test.py:26:13 - error: Argument missing for parameter "blah" (reportGeneralTypeIssues)
  ./test.py:26:13 - error: "assert_type" mismatch: expected "str" but received "Unknown" (reportGeneralTypeIssues)
2 errors, 0 warnings, 0 informations 

This smells a lot like the problem with getting functools.cache to work both with methods and functions, see e.g. https://github.com/python/typeshed/issues/6347

Commencez par exécuter la reproduction minimale en Python 3.11 avec pyright et comparez-la avec mypy. Examinez ensuite le stub typeshed de functools.wraps, en vous concentrant sur la manière dont il représente les fonctions et méthodes décorées. C’est terminé lorsque l’exemple de méthode de classe passe la vérification de types et que assert_type(instance.my_method(5), str) ne signale aucune erreur.