Invalid type inferred when overloading __call__ with generic self-type

[unmade]

Seems like mypy uses the first overloaded __call__ signature when using self-type. There is no problem with overloading another dunder method (I tried __get__) or with regular overload (__call__ but without self-type). If use another method name, for example call, then everything works fine.

Below is snippet to illustrate the problem:

from typing import Awaitable, Callable, Generic, TypeVar, overload

T = TypeVar("T", "Handler", "AsyncHandler")

Handler = Callable[[], "Result"]
AsyncHandler = Callable[[], Awaitable["Result"]]


class Result:
    pass


class Middleware(Generic[T]):
    def __init__(self, handler: T):
        self.handler: T = handler 

    @overload
    def __call__(self: "Middleware[Handler]") -> Result:
        ...
    @overload
    def __call__(self: "Middleware[AsyncHandler]") -> Awaitable[Result]:
        ...

    def __call__(self):
        return self.handler()

    @overload
    def call(self: "Middleware[Handler]") -> Result:
        ...
    @overload
    def call(self: "Middleware[AsyncHandler]") -> Awaitable[Result]:
        ...

    def call(self):
        return self.handler()


def handler() -> Result:
    return Result()


async def async_handler() -> Result:
    return Result()


reveal_type(Middleware(handler))  # OK, type is 'Middleware[def () -> Result]'
reveal_type(Middleware(async_handler))  # OK, type is 'Middleware[def () -> Awaitable[Result]]'
reveal_type(Middleware(handler)())  # OK, type is 'Result'
reveal_type(Middleware(handler).call())  # OK, type is 'Result'
reveal_type(Middleware(async_handler)())  # WRONG, type is 'Result', expected 'Awaitable[Result]'
reveal_type(Middleware(async_handler).call())  # OK, type is 'Awaitable[Result]'

[JukkaL]

Yeah, this looks like a bug.

@ilevkivskyi Any idea if this would be hard to fix?

[ilevkivskyi]

__call__ is special-cased in checkmember.py, it may be not easy to fix. I don't remember why, but last time I tried it, I didn't find a quick solution.

[arvidfm]

Just confirming that this is still an issue as I lost a lot of time to it today: https://mypy-play.net/?mypy=master&python=3.11&gist=c248b6ab66c0b004249f229971f7ae2f

Any idea if this might get looked at anytime soon?