Incompatible generic types with asynccontextmanager

[NicholasJohnstone]

Bug Report
Mypy reports an incompatible type error when using a generic asynccontextmanager. When using the non-async equivalent there is no error.

To Reproduce

from typing import Type, TypeVar, AsyncIterator, Iterator, Generic
import contextlib

T = TypeVar("T")


@contextlib.contextmanager
def create(my_type: Type[T]) -> Iterator[T]:
    yield my_type()


@contextlib.asynccontextmanager
async def async_create(my_type: Type[T]) -> AsyncIterator[T]:
    yield my_type()


class Foo(Generic[T]):
    def do_something(self, t: T) -> None:
        pass

    def example(self, my_type: Type[T]) -> None:
        with create(my_type) as value1:
            self.do_something(value1)

    async def async_example(self, my_type: Type[T]) -> None:
        async with async_create(my_type) as value2:
            self.do_something(value2)

Mypy reports error: Incompatible types in assignment (expression has type "T", variable has type "T") for the self.do_something(value2) line.

Expected Behavior
No error for the above example

Your Environment

• Mypy version used: 0.910
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.9.7
• Operating system and version: Ubuntu 20.04

[hauntsaninja]

I think fixed on master by #11352