Generic type alias with param spec

[bersbersbers]

Bug Report

In the code below, decorator_pass works fine while decorator_fail fails. The only difference between the two is that I extracted Callable[[Method[C, P, T]], Method[C, P, T]] into its own variable (a generic type alias, if I am not mistaken).

I had expected this to be a duplicate of #11855, but that one is presumably fixed now.

To Reproduce

https://mypy-play.net/?mypy=latest&python=3.11&gist=077268582efbbbc19e671b7477cdadda

from typing import Any, Callable, Concatenate, ParamSpec, TypeVar

C = TypeVar("C")
P = ParamSpec("P")
T = TypeVar("T")
Method = Callable[Concatenate[C, P], T | None]

def decorator_pass() -> Callable[[Method[C, P, T]], Method[C, P, T]]:
    def decorator(func: Method[C, P, T]) -> Method[C, P, T]:
        def wrapper(self: C, /, *args: Any, **kwargs: Any) -> T | None:  # noqa: ANN401
            return func(self, *args, **kwargs)
        return wrapper
    return decorator

Wrapper = Callable[[Method[C, P, T]], Method[C, P, T]]
def decorator_fail() -> Wrapper[C, P, T]:
    def decorator(func: Method[C, P, T]) -> Method[C, P, T]:
        def wrapper(self: C, /, *args: Any, **kwargs: Any) -> T | None:  # noqa: ANN401
            return func(self, *args, **kwargs)
        return wrapper
    return decorator

class Class:
    @decorator_pass()
    def fun_pass(self, /) -> None:
        pass

    @decorator_fail()
    def fun_fail(self, /) -> None:
        pass

Expected Behavior

No error

Actual Behavior

main.py:28: error: Argument 1 has incompatible type "Callable[[Class], None]"; expected "Callable[[, VarArg(), KwArg()], | None]" [arg-type]

Your Environment

• Mypy version used: 1.4.0
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.11.4

[ilevkivskyi]

This is a duplicate of #3924

[hauntsaninja]

@bersbersbers is the project you were running into this on open source?

[bersbersbers]

@bersbersbers is the project you were running into this on open source?

It may be one day, but if so, that day will be far out. So unfortunately, no.