I'm actually struggling to think of situations where typing.SupportsInt would be useful in its current form: if I'm writing a function that wants to do a duck-typed acceptance of integer-like things (for example because I want my function to work with NumPy integers as well as plain old Python ints) then I want an __index__ check rather than an __int__ check. If I'm writing a function that allows general numeric inputs, then I'm not sure why I'd be calling 'int' on those inputs.

As another data point, complex supporting __int__ is a little bit of an oddity, since all that __int__ method does is raise a TypeError.

@Michael: are you in a position to share the use-case that motivated opening the issue? I'd be interested to see any concrete uses of typing.SupportsInt.

Maybe typing.SupportsIndex (or typing.UsableAsInt, or ... --- naming things is hard) is what we actually need?

On this particular issue: I'm not opposed to adding __int__ to fractions.Fraction purely for the sake of consistency, but it's not yet clear to me that it solves any real issue.