Property setter and getter types can't differ

[JukkaL]

This was reported by @srittau in #220 (comment):

It also seems that the getter and setter need to have the same type at the moment:

class Foo:
    @property
    def bar(self) -> str: ...
    @bar.setter
    def bar(self, v: int) -> None: ...

Foo().bar = 3

This will cause mypy 0.550 to complain:

foo.py:7: error: Incompatible types in assignment (expression has type "int", variable has type "str")

While this example is a bit silly, I have a real-world example involving setting arbitrary Mappings and getting a custom Mapping subtype.

[ilevkivskyi]

Closing as duplicate of #3004 that has more discussion and typical use cases (non-optional getters and container normalization).