`Borrowed<PyType>::name` is not consistent

[wyfo]

With #[cfg(not(any(Py_LIMITED_API, PyPy)))], Borrowed<'a, '_, PyType>::name implementation delegates to tp_name.
However, tp_name is not consistent.
For pure Python types Borrowed<'a, '_, PyType>::name returns different result if compiled with or without abi3 feature.

Solution

Make Borrowed<'a, '_, PyType>::name follow __name__ behavior, and expose Borrowed<'a, '_, PyType>::module.

I will open a PR.

[adamreichold]

Make Borrowed<'a, ', PyType>::name follow name behavior, and expose Borrowed<'a, ', PyType>::module.

IIRC, we made the concicous decision to expose tp_name and not follow __name__. However, they should match when using the abi3 feature as we access __module__ and __name__ in that case to "emulate" tp_name.

[wyfo]

The issue is that it's hard (if not impossible) to emulate tp_name, because it's not consistent across types: for list, it's "list", for datetime.date, it's "datetime.date", for asyncio.CancelledError, it's "CancelledError", etc.

With abi3 enabled, so without access to tp_name, I can't find a simple rule to determine how it behaves. That's the point of PEP 737.

That's why I think we cannot expose tp_name like that, as consistency with abi3 is way more important to me.
Do you have another solution?

[adamreichold]

Do you have another solution?

Isn't using what you implemented as full_name for name basically a solution which fixes the inconsistencies between the builds? Why not just use that for name?

[wyfo]

Isn't using what you implemented as full_name for name basically a solution which fixes the inconsistencies between the builds? Why not just use that for name?

I feel a little stupid 😅 However, we have to consider that most of the calls to this new PyType::name implementation may have to retrieve __module__, making it not so efficient.
That's an argument in favor of my proposal, with an efficient PyType::name implementation, and a less efficient PyType::full_name.

Anyway, I can modify my PR if you judge that it is worth it.

[davidhewitt]

This got resolved in #4196