a Type is not recognized properly for subclassing

Bug Report

I'm explicitly typing a variable with Type (or type) and mypy thinks I should not subclass it.

To Reproduce

from typing import Type

class Base:
    ...

def get_base() -> Type[Base]:
    return Base

BaseAlias: Type[Base] = get_base()

class Derived(BaseAlias):
    ...

Expected Behavior

There should be no error. I'm subclassing a type, which is ok. Furthermore, mypy has the information that it's a type so subclassing should not be questioned.

Actual Behavior

footypes.py:11: error: Variable "footypes.BaseAlias" is not valid as a type
footypes.py:11: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#variables-vs-type-aliases
footypes.py:11: error: Invalid base class "BaseAlias"
Found 2 errors in 1 file (checked 1 source file)

Same behavior if specifying BaseAlias: type = get_base() instead.

Your Environment

• Mypy version used: 0.910
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: 3.9.0
• Operating system and version: python:3.9 docker image

Comienza con el reproductor mínimo mostrado en footypes.py y ejecuta mypy sobre él para confirmar los dos diagnósticos de BaseAlias. Traza cómo se analizan las anotaciones de variables y las clases base, y después añade cobertura de regresión que demuestre que el ejemplo no produce errores.