[1.4] Regression with AsyncGenerator

[Dreamsorcerer]

Bug Report

I can't seem to find a minimal reproducer, but whenever using watchfiles.awatch(), mypy produces the error:
error: "Coroutine[Any, Any, AsyncGenerator[set[tuple[Change, str]], None]]" has no attribute "__aiter__" (not async iterable) [attr-defined]

As can be seen in the aiohttp-devtools repo:
https://github.com/aio-libs/aiohttp-devtools/actions/runs/5328161994/jobs/9652470528?pr=572

To Reproduce

from watchfiles import awatch

async def main() -> None:
    async for i in awatch("/foo"):
        print(i)

Expected Behavior

No error, as in mypy<1.4.
Not sure what exactly triggers the error, as writing another async iterator function myself does not trigger it.

[Dreamsorcerer]

Source code is just annotated with AsyncGenerator:
https://github.com/samuelcolvin/watchfiles/blob/main/watchfiles/main.py#L137

[hauntsaninja]

Hmmm I wonder if related to #14150

[hauntsaninja]

Yeah, I think so, cc @JukkaL (btw, thanks again for the change, it's a huge perf win for various codebases at work)

λ cat main.py
from third_party import awatch

async def main() -> None:
    async for i in awatch("/foo"):
        reveal_type(i)

λ cat third_party.py 
# mypy: ignore-errors
from typing import AsyncGenerator

async def awatch(path: str) -> AsyncGenerator[int, None]:
    if False:
        yield

Reminder to self: add aiohttp-devtools to mypy_primer

[hauntsaninja]

Okay, I have the fix

[Dreamsorcerer]

Reminder to self: add aiohttp-devtools to mypy_primer

If you'd like some other aio-libs candidates, I'd suggest any of aiohttp-security, aiohttp-admin, aiohttp-jinja2, aiohttp-session and multidict.
I also noticed aioredis is in there, but that project has migrated to upstream redis now, so is no longer maintained.

[hauntsaninja]

Fixed and released in mypy 1.4.1