(🐞) `staticmethod` special-casing causes error to not be reported

If we copy the implementation of staticmethod from typeshed, mypy correctly reports the error here.

So it seems that mypys dedicated special-casing of staticmethod is causing this issue to be incorrectly not reported.

from collections.abc import Callable
from typing import Generic, ParamSpec, TypeVar, overload

P = ParamSpec("P")
T = TypeVar("T")
R_co = TypeVar("R_co", covariant=True)


def contextmanager(fn: Callable[P, R_co]) -> Callable[P, R_co]:
    def func(*args: P.args, **kwargs: P.kwargs) -> R_co:
        return fn(*args, **kwargs)
    return func


class staticmethod_copy(Generic[P, R_co]):
    @property
    def __func__(self) -> Callable[P, R_co]: ...
    @property
    def __isabstractmethod__(self) -> bool: ...
    def __init__(self, __f: Callable[P, R_co]) -> None: ...
    @overload
    def __get__(self, __instance: None, __owner: type) -> Callable[P, R_co]: ...
    @overload
    def __get__(self, __instance: T, __owner: type[T] | None = None) -> Callable[P, R_co]: ...
    __name__: str
    __qualname__: str
    @property
    def __wrapped__(self) -> Callable[P, R_co]: ...
    def __call__(self, *args: P.args, **kwargs: P.kwargs) -> R_co: ...

# Just the relevant part of staticmethod definition that is needed
#class staticmethod(Generic[P, R_co]):
#    def __init__(self, __f: Callable[P, R_co]) -> None: ...
#    def __call__(self, *args: P.args, **kwargs: P.kwargs) -> R_co: ...

class Foo:
    @contextmanager
    @staticmethod_copy
    def copy() -> None: ...

    @contextmanager
    @staticmethod
    def native() -> None: ...


Foo().copy()   # ✅ error: Attribute function "copy" with type "Callable[[], None]" does not accept self argument  [misc]
Foo().native()  # ❌no error

• from https://github.com/python/mypy/issues/15911#issuecomment-1716790989

提供された例を再現し、mypy の staticmethod 専用の特別扱いと、コピーした typeshed の実装を比較する。デコレータと descriptor 型がどのように解析されるかを追跡する。完了条件は、Foo().copy() の場合と同様に、mypy が Foo().native() に対して missing-self エラーを報告することである。