Bug Report

It apprears that mypy is not aware that starting with Python 3.10 async context managers created using contextlib.asynccontextmanager can be used as decorators.

To Reproduce

The following is example code from the Python docs for contextlib.asynccontextmanager. Running mypy against it results in the error included below the code.

import time
from contextlib import asynccontextmanager


@asynccontextmanager
async def timeit():
    now = time.monotonic()
    try:
        yield
    finally:
        print(f"it took {time.monotonic() - now}s to run")


@timeit()
async def main():
    pass

$ mypy example.py
example.py:14: error: "AsyncContextManager[Any]" not callable
Found 1 error in 1 file (checked 1 source file)

Expected Behavior

The example code should type check without problems on Python 3.10+

Actual Behavior

Mypy complains that the context manager is not callable.

Your Environment

• Mypy version used: 0.920
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.10.1
• Operating system and version: macOS 10.15.7