@total_ordering support

[srittau]

Please consider the following code:

from functools import total_ordering
from typing import Any


@total_ordering
class Ord:

    def __eq__(self, other: Any) -> bool:
        return False

    def __lt__(self, other: "Ord") -> bool:
        return False


Ord() <= Ord()

mypy 0.560 (using Python 3.6.4, default flags) complains:

test.py:15: error: Unsupported left operand type for <= ("Ord")

It would be helpful if mypy would support @total_ordering.

[gvanrossum]

Perhaps the implementation of this could be a plugin. There are likely ideas to copy from the attrs plugin that David Euresti recently contributed (though that one has a wider scope).

[chadrik]

+1. Just got hit by this one.

[gvanrossum]

Maybe someone can submit a PR.

[aldanor]

Can the implementation like pantsbuild/pants#9525 be utilized in base mypy?

[JelleZijlstra]

@aldanor that seems reasonable, since this is a standard library function.