Type override for attributes is not checked

[dmoisset]

from what I see, overriding an attribute with an incompatible type (which can lead to unsoundness) does not produce any kind of warning with mypy:

class Base:
    attr = "foo"

    def f(self) -> str:
        return self.attr

class Derived(Base):
    attr = 42

d = Derived()

reveal_type(d.f())

The code above shows that mypy thinks that the d.f() expression is a string, while it's actually an int. Shouldn't this kind of redefinitions be forbidden?

[gvanrossum]

IIRC there's an issue for this already. It's definitely a bug.

…

--Guido (mobile)

[dmoisset]

I have looked before opening but couldn't find one... After a second look, there's a mention to this in #1338 , but they seem to be two related but distinct issues.

[gvanrossum]

Still I suspect that they can be fixed with one PR. Shouldn't even be that hard.

[gvanrossum]

Fixed by #2510.