mypy not catching needing to specify a forward declaration.

[asincero]

Steps to reproduce

mypy doesn't detect the need for a forward declaration. For example:

class Foo:
    def bar(o: Foo) -> None:
        print('bar called')
        
o = Foo()
o.bar()

Current behavior

mypy doesn't detect anything wrong with the above code.

Expected behavior

mypy should flag the reference to "Foo" on line 2 as being undefined.

mypy --version output

mypy 0.570

[gvanrossum]

True. Alternatively, in Python 3.7 you will be able to write from __future__ import annotations and then annotations will no longer be evaluated when encountered at runtime.

[ilevkivskyi]

Duplicate of #948