`typing.get_type_hints` cannot resolve forward references in `cls.__init__` annotations

[mwchase]

The is related to #593/#760. Because #760 populates the generated __init__ method's globals at the time that the class is created, new globals aren't visible to get_type_hints by default.

Example code demonstrating this:

import attrs
import typing

@attrs.define
class HasForwardRef:
    ref: "ClassDefinedLater"

class ClassDefinedLater:
    pass

typing.get_type_hints(HasForwardRef.__init__)

This last call raises an error.

I've got a workaround for this in the code where I hit this, but it really wasn't obvious at first what was going on.

[hynek]

I'm not sure what to do about this – is it fixable yet at all?