annotating type instance

[tumb1er]

I'm trying to annotate simple class factory, but constantly getting "Invalid base class" error. Only annotating the result of factory() call with Any return type removes errors, but there is an interesting thing at line 26.
Revealed type for class A is a function that returns A instance, but you can't inherit from real function.
So, two questions:

• how to annotate factory to return something that is "valid base class"?
• may be mypy should distinguish type instance and class instance "constructor"?

from typing import Any


class A:
    pass


def factory() -> Any:
    return A


base = factory()  # type: Any
# removing forced Any leads to invalid base class error

reveal_type(base)
# factory.py:15: error: Revealed type is 'Any'


class B(base):
    pass


var = A


reveal_type(var)
# factory.py:26: error: Revealed type is 'def () -> factory.A'


class C(var):
    pass

[ilevkivskyi]

Normally you would annotate a function that returns a class as

def factory() -> Type[A]:
    return A

a = factory()() # a is correctly inferred to have type A

I think the problem is that mypy currently does not support expressions in base classes or other dynamic features see e.g. #1764

[tumb1er]

Found dynamic base classes in unsupported features, so my questions are now about these features only. Without dynamic base classes, all annotations look reasonable.