update allowlist comment for SupportsAbs and SupportsRound

[tungol]

The answer to the question is that mypy infers it just fine, but stubtest doesn't check for attributes inherited from the metaclass because that's almost never what we want. In this case, the runtime implementation doesn't get __type_params__ from builtins.type either. It's actually defined for the class due to the use of PEP-695 syntax.

We can see the difference between inheriting from type and having it on the class:

class Foo(SupportsAbs):
    def __abs__(self):
        return 1

class Bar(SupportsIndex):
    def __index__(self):
        return 1

Given these classes:

>>> Foo.__type_params__
()
>>> Foo().__type_params__
(T,)
>>> Bar.__type_params__
()
>>> Bar().__type_params__
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Bar' object has no attribute '__type_params__'

or alternatively:

>>> getattr_static(SupportsAbs, '__type_params__')
(T,)
>>> getattr_static(SupportsIndex, '__type_params__')
<attribute '__type_params__' of 'type' objects>

This might go away eventually when typeshed adopts PEP-695 syntax for it's type variables? I'm not sure.

[github-actions]

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉

[hauntsaninja]

Thank you!