Mypy disallows overriding a generic type attribute with a property

[mmdanggg2]

Bug Report

If I have a generic class with an attribute of a generic type, when creating a concrete subclass, overriding that attribute with a correctly typed property raises an error. Similar to #4125

To Reproduce

from typing import TypeVar, Generic

T = TypeVar("T")

class A(Generic[T]):
 def __init__(self, val: T):
 self.member: T = val

class B(A[str]):
 @property
 def member(self) -> str:
 return "bar"
 
 @member.setter
 def member(self, val: str):
 pass

Actual Behavior

property_issue.py:10: error: Signature of "member" incompatible with supertype "A" [override]
property_issue.py:10: note: Superclass:
property_issue.py:10: note: T
property_issue.py:10: note: Subclass:
property_issue.py:10: note: str

Your Environment

• Mypy version used: 1.9.0
• Mypy command-line flags: -
• Mypy configuration options from mypy.ini (and other config files): -
• Python version used: 3.9.13