"SupportsInt" doesn't work with Union types

[sangsta]

The following shouldn't be an error:
error: Argument 1 to "int" has incompatible type "Union[unicode, int]"; expected "SupportsInt"

[ddfisher]

In particular, you can repro this for Python 2 with:

from typing import Union
x = 0  # type: Union[int, unicode]
int(x)

[elazarg]

I would guess it is another example of #2128 and the general overloading/Union problem.

[nolanlum]

FYI this is still an issue in Python 3.6:

error: Argument 1 to "int" has incompatible type "Union[int, str]"; expected "SupportsInt"

[emmatyping]

Yes, this is an issue in mypy's union deduction checks, and is independent of Python version.

[ilevkivskyi]

This issue is now fixed (example correctly passes).