False negative when narrowing attribute type in subclass

[LeeeeT]

Bug Report

Mypy doesn't complain about redefining an attribute in a subclass with a narrower type. I expect the following code to produce a static type checking error:

class A:
    f: object

class B(A):
    f: float

Since this will fail:

b = B()

a: A = b
a.f = "abc"

b.f.is_integer()

Your Environment

• Mypy version used: 0.960
• Mypy configuration options: strict=true
• Python version used: 3.10

[hauntsaninja]

Thanks, duplicate of #3208