__set_name__ isn't checked

[natedogith1]

from typing import Type

class Foo:
	def __set_name__(self, owner: Type['Bar'], name: str) -> None:
		...

class Bar:
	foo_bar = Foo() # correctly passes

class Baz:
	foo_baz = Foo() # should fail

mypy correctly accepts Bar.foo_var, but incorrectly accepts Baz.foo_baz

[ethanhs]

I believe mypy isn't aware of __set_name__, this should be implemented.

I believe the generic definition of this is:

def __set_name__(self, owner: Type[Any], name: str) -> None: ...

We perhaps might be able to specialize based on the type of owner.