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AsyncGenerator/AsyncIterable do not work with overloaded async def #14996
Description
Bug Report
When using typing.overload with an async function that returns an AsyncGenerator or AsyncIterable, the overloads fail with Overloaded function implementation cannot produce return type of signature # when defined using async def
To Reproduce
Failure case: https://mypy-play.net/?mypy=latest&python=3.11&gist=f9b64edbf09acd4b1952f5753669c2e7
from typing import AsyncGenerator, overload
@overload
async def foo(*, a: int) -> AsyncGenerator[int, None]:
...
@overload
async def foo(*, b: int) -> AsyncGenerator[int, None]:
...
async def foo(*, a: int | None = None, b: int | None = None) -> AsyncGenerator[int, None]:
if a is not None:
for i in range(a):
yield i
elif b is not None:
for i in range(b):
yield i
else:
yield -1Unexpected success case: https://mypy-play.net/?mypy=latest&python=3.11&gist=2fcc9c2372664f4ce257a9cec2849698
from typing import AsyncGenerator, overload
@overload
def foo(*, a: int) -> AsyncGenerator[int, None]:
...
@overload
def foo(*, b: int) -> AsyncGenerator[int, None]:
...
async def foo(*, a: int | None = None, b: int | None = None) -> AsyncGenerator[int, None]:
if a is not None:
for i in range(a):
yield i
elif b is not None:
for i in range(b):
yield i
else:
yield -1Expected Behavior
no errors when overloads are also defined with async def and error when overloads are defined with def
Actual Behavior
when overloads are defined with async def:
main.py:11: error: Overloaded function implementation cannot produce return type of signature 1 [misc]
main.py:11: error: Overloaded function implementation cannot produce return type of signature 2 [misc]
Found 2 errors in 1 file (checked 1 source file)
when overloads are defined with def: no errors
Your Environment
- Mypy version used: 1.1.1 (mypy-play)
- Python version used: 3.11 (mypy-play)
Activity
hauntsaninja commentedon Apr 2, 2023
Your success case is expected and is the recommend thing to do. I just added some more documentation for this last week in #14973, see https://mypy.readthedocs.io/en/latest/more_types.html#asynchronous-iterators
Also mention overloads in async iterator documentation
Also mention overloads in async iterator documentation (#14998)