Generic class with ParamSpec isn't callable as far as partial is concerned

[NeilGirdhar]

from collections.abc import Callable
from functools import partial
from typing import Generic, TypeVar

from typing_extensions import ParamSpec

R_co = TypeVar('R_co', covariant=True)
P = ParamSpec('P')

class X(Generic[P, R_co]):
 def __init__(self, f: Callable[P, R_co]):
 super().__init__()
 self.f = f

 def __call__(self, /, *args: P.args, **kwargs: P.kwargs) -> R_co:
 return self.f(*args, **kwargs)

@partial(X) # error: Argument 1 to "partial" has incompatible type "Type[X[Any, Any]]"; expected "Callable[..., X[P, R_co]]" [arg-type]
def f() -> int:
 return 2

print(f())

[gschaffner]

oddly, Mypy accepts X as a Callable[P, T_co] here—it's specifically Callable[..., T_co] that it's rejecting:

class X(Generic[P, T_co]):
 def __init__(self, func: Callable[P, T_co], /) -> None:
 self._func = func

 def __call__(self, *args: P.args, **kwargs: P.kwargs) -> T_co:
 return self._func(*args, **kwargs)


class badX(Generic[T_co]):
 # the same wrapper thing, but "typed" (really, half-typed) like :class:`~functools.partial`.
 def __init__(self, func: Callable[..., T_co], /) -> None:
 self._func = func

 def __call__(self, *args: Any, **kwargs: Any) -> T_co:
 return self._func(*args, **kwargs)


X(X)
badX(X) # error: Argument 1 to "badX" has incompatible type "Type[X[Any, Any]]"; expected "Callable[..., X[P, T_co]]" [arg-type]

(https://mypy-play.net/?mypy=1.1.1&python=3.11&gist=75162691fee56d70787ee7a94896a081)

[ilevkivskyi]

The original example works on master, likely fixed by #15837