Unsupported Base

What it does

Checks for class definitions that have bases which are unsupported by ty.

Why is this bad?

If a class has a base that is an instance of a complex type such as a union type, ty will not be able to resolve the method resolution order (MRO) for the class. This will lead to an inferior understanding of your codebase and unpredictable type-checking behavior.

Examples

import datetime


class A: ...


class B: ...


if datetime.date.today().weekday() != 6:
    C = A
else:
    C = B


class D(C): ...  # error: [unsupported-base]