async with usage with asynccontextmanager-decorated function results in Unknown #1804
Description
Consider the following example, where the usage of a asynccontextmanager-decorated function in an async with statement results in an Unknown type:
from contextlib import asynccontextmanager
from typing import AsyncGenerator
class Session: ...
@asynccontextmanager
async def connect() -> AsyncGenerator[Session]:
yield Session()
async def main():
async with connect() as session:
# TODO: should be `Session`
reveal_type(session) # revealed: UnknownThe problem is that we currently infer () -> _AsyncGeneratorContextManager[Unknown, None] for connect. The signature of asynccontextmanager is:
def asynccontextmanager(func: Callable[_P, AsyncIterator[_T_co]]) -> Callable[_P, _AsyncGeneratorContextManager[_T_co]]so this requires generics-solver support for Callable and generic protocols.
Note that we have a test for this here: https://github.com/astral-sh/ruff/blob/a364195335eb920ff429c43832c4ee464051ea9a/crates/ty_python_semantic/resources/mdtest/with/async.md?plain=1#L203-L222