super() erroneously flagged as incorrect when cls function parameter is generic

[wadetregaskis-linkedin]

from typing import Type, TypeVar

T = TypeVar('T', bound='BaseClass')

class BaseClass:
    pass

class SubClass(BaseClass):
    @classmethod
    def foo(cls: Type[T]) -> None:
        super().bar()

mypy 0.730 newly (vs 0.720) reports the false error:

error: Argument 2 for "super" not an instance of argument 1

[wadetregaskis-linkedin]

(ignoring that in this contrived, condensed example there is no bar - in my real code there's no such issues and it definitely works as intended at runtime irrespective of mypy's opinions)

[JukkaL]

The error message is confusing, but I think that mypy is technically correct. The bound for T should be SubClass, not BaseClass.

[wadetregaskis-linkedin]

Hmm, perhaps my example is missing some pertinent details. In my actual use, bar is a method defined in BaseClass, and foo is overriding the implementation from BaseClass. As such it needs to preserve the method signature of the original method, which is to return an instance of the generic T.

[AlexWaygood]

I'm closing this issue in favour of #9282 (a newer issue, but it has a lot more discussion attached to it, and it's the same behaviour on display)