[1.12, 1.13 regression] typing.overload and ParamSpec #18027

from __future__ import annotations

from types import TracebackType
from typing import Any, AsyncContextManager, Callable, TypeVar, overload

from typing_extensions import ParamSpec, Self

T = TypeVar("T")
P = ParamSpec("P")


class Animal:
    async def __aenter__(self) -> Self:
        return self

    async def __aexit__(
        self,
        typ: type[BaseException] | None,
        exc: BaseException | None,
        tb: TracebackType | None,
    ) -> None:
        return None

    def __call__(self) -> str:
        return "name"


@overload
def name(animal: AsyncContextManager[T]) -> T: ...


@overload
def name(
    animal: Callable[P, T],
    *_args: P.args,
    **_kwargs: P.kwargs,
) -> T: ...


# BUT!
# if replace the second overload with
# @overload
# def name(animal: Callable[[], T]) -> T: ...
# or even
# def name(animal: Callable[[int], T]) -> T: ...
# everything works fine


def name(
    animal: Any,
    *_args: Any,
    **_kwargs: Any,
) -> Any:
    return animal


dog = Animal()
dog2: Animal = name(dog)