Derived method completions use incorrect return type annotations when differing by `async` modifier.

[DanielRosenwasser]

Possibly related to #4831?

Environment data

• Language Server version: v2024.2.104
• OS and version: Windows
• Python version (& distribution if applicable, e.g. Anaconda): 3.12

Code Snippet

Minimal example:

from typing import Awaitable

class Base:
    def yadda(self) -> Awaitable[int]:
        ...

class Derived(Base):
    async def ya$

Repro Steps

Assume $ is the cursor. Request completions at the cursor. Commit to the completion entry for __aenter__.

Expected behavior

For minimal example:

class Base:
    def yadda(self) -> Awaitable[int]:
        ...

class Derived(Base):
    async def yadda(self) -> int:
        return super().yadda()

Actual behavior

Pylance annotates uses the type that works for the non-async base, but one that does not work for the async derived type. The derived method is marked as async, so the method shouldn't declare it returns an Awaitable, a Coroutine, or whatever.

class Base:
    def yadda(self) -> Awaitable[int]:
        ...

class Derived(Base):
    async def yadda(self) -> Awaitable[int]:
        return super().yadda()

---

Here's something closer to what I actually ran into:

from typing import AsyncContextManager

class Yadda(AsyncContextManager):
    async def _$

Expected

class Yadda(AsyncContextManager):
    async def __aenter__(self) -> Self:
        return await super().__aenter__()

Actual

class Yadda(AsyncContextManager):
    async def __aenter__(self) -> Coroutine[Any, Any, _T_co]:
        return await super().__aenter__()

[DanielRosenwasser]

(generator functions might not have this issue since I don't think they become generators unless they have a yield statement)

[DanielRosenwasser]

also, it's not entirely about whether the modifiers differ - in the second example I gave, __aenter__ is declared as async but has no explicit return type annotation.

[debonte]

@DanielRosenwasser, can you check your "minimal example" above? It is missing the $ and seems like it might be a copy of the "actual behavior" code.

[DanielRosenwasser]

My apologies - I started out with the bottom example, figured it should be more minimal, but got sloppy. Fixed now.

Also, here's the same example on the Pyright playground if you want an easy repro.