PyNumber_InPlacePower can now just mirror the other PyNumber_InPlace* functions, right?

So this is the only line that's needed here.

Ah yes, thank you.

It looks like we're also lacking a test for when A doesn't define __ipow__. Do you mind adding one?

Sure, added the test

Could you add a test for the two fallbacks and ensure the same class is returning NotImplemented and implementing the regular power methods i.e something like:

class A:
    def __ipow__(self, other):
        return NotImplemented

class B(A):
    def __pow__(self, other):
        return 1
class C(A):
    def __rpow__(self, other):
        return 2

The linked bug is only exhibited when a class has an ipow slot but when called it returns NotImplemented.

Not sure I understood correctly what you meant, but I updated the test to also test the __pow__ fallback.

Thank you, what you have now looks good. What I meant was that to catch the original bug/properly be a regression test, the class has to look like:

class A:
    def __ipow__(self, _):
        return NotImplemented
    def __pow__(self, other):
        ...

if the class looks like

class A:
    def __pow__(self, other):
        ...

then the old logic returns a false here and correctly goes to the non-inplace version of power anyway:

Ah yes, you are right. Thanks!

This can just be:

Then you don't need the class definition above!

Done.

Could you add a test for the two fallbacks and ensure the same class is returning NotImplemented and implementing the regular power methods i.e something like:

class A:
    def __ipow__(self, other):
        return NotImplemented

class B(A):
    def __pow__(self, other):
        return 1
class C(A):
    def __rpow__(self, other):
        return 2

The linked bug is only exhibited when a class has an ipow slot but when called it returns NotImplemented.

Just fyi, @brettcannon posted on the original bug pointing out that this would not call __pow__ either. I'd recommend changing this to

If :func:`object.__ipow__` returns :const:`NotImplemented`, the operator will correctly
fall back to :func:`object.__pow__` and :func:`object.__rpow__` as expected.

It might also be worth mentioning this in whatsnew, even though it's obscure it is potentially a change in behavior that people should be informed about.

Updated the news entry, and also added a line to What's New

Thanks for fixing this! Really weird that op_name went unused so long. Would you mind adding a test for this like:

        x = None
        with self.assertRaises(TypeError) as cm:
            x **= 2
        self.assertIn('unsupported operand type(s) for **=', str(cm.exception))

Thanks, added a new test

Thank you, what you have now looks good. What I meant was that to catch the original bug/properly be a regression test, the class has to look like:

class A:
    def __ipow__(self, _):
        return NotImplemented
    def __pow__(self, other):
        ...

if the class looks like

class A:
    def __pow__(self, other):
        ...

then the old logic returns a false here and correctly goes to the non-inplace version of power anyway: