isinstance + generator results in unexpected error

[JukkaL]

This code doesn't generate errors:

class A:
    y = False
a = None # type: object
(a.y for a in [A()])

However, this generates (just added isinstance):

class A:
    y = False
a = None # type: object
if isinstance(a, int): pass   # only difference
(a.y for a in [A()])

Output is like this:

program.py:7: error: "object" has no attribute "y"

The latter program shouldn't generate any error. There seems to be some weird interaction between isinstance and generator scoping.

[JukkaL]

Ah, the type in the conditional type binder probably gets propagated to the generator even though that variable there is in a different scope.

[emmatyping]

The second example works fine at least in 0.510, so Im closing this.