error: Return type of <functionName> incompatible with supertype <ClassName>

[YuvalPruss]

I got a code that looks like this:

from typing import NamedTuple, Dict, Optional, List, Any


class Object1(object, metaclass=ABCMeta):
    def __init__(self) -> None:
        pass

    @abstractmethod
    def get_logo(self) -> Optional[str]:
        pass


class Object2(Object1):
    def __init__(self) -> None:
        super().__init__()

    async def get_logo(self) -> Optional[str]:
        return ''


class Object3(Object1):
    def __init__(self) -> None:
        super().__init__()

    async def get_logo(self) -> Optional[str]:
        return None

And the mypy alerts me that:

test.py:19: error: Return type of "get_logo" incompatible with supertype "Object1"
test.py:27: error: Return type of "get_logo" incompatible with supertype "Object1"

But it's look OK to me, because they return the same type...
I run it with: mypy --strict-optional --ignore-missing-imports <file>

[JukkaL]

Object doesn't use async def but subclasses use it, so the actual return types are different, though the annotations look the same.

[YuvalPruss]

Great! It's corrects my errors, but let me get that straight- what is the difference in the type annotations between async def and def? Should I wrote something differently? Maybe use the typing.Coroutine as the returned type from the async defs?

[JukkaL]

Mypy internally uses typing.Awaitable[x] as the return type for async def, but this wrapping happens automatically so your signatures are fine. You can use reveal_type(obj.method) to display the signature of a method as mypy sees it.