Namespace change for Enum pickling in 0.28

[mikelync]

Bug Description

In versions <0.28 we have found ways to pickle complex enums of any form (see discussion #5226). The one thing necessary in Python was to monkey-patch the namespace (otherwise Python's native pickling functionality would not generate the right objects). E.g. I required:

mymodule.rs.MyEnum_A = mymodule.rs.MyEnum.A
mymodule.rs.MyEnum_B = mymodule.rs.MyEnum.B
mymodule.rs.MyEnum_C = mymodule.rs.MyEnum.C

0.28 broke many of the pickling tests. The solution was to adjust the above to:

mymodule.rs.A = mymodule.rs.MyEnum.A
mymodule.rs.B = mymodule.rs.MyEnum.B
mymodule.rs.C = mymodule.rs.MyEnum.C

But this doesn't seem like a very good idea because of a potential name overlap with two different Enums. Fortunately we had no overlap and our code can update to 0.28 as is but if we were to have had: MyEnum.A and MyEnum2.A then we cannot do the above because mymodule.rs.A cannot be dual assigned.

You can see our 0.28 upgrade PR here: attack68/rateslib#1212

Steps to Reproduce

Create a complex enum as pyclass and examine the namespace constructed in Python for your module.

Backtrace

Your operating system and version

windows

Your Python version (python --version)

3.10+

Your Rust version (rustc --version)

1.87

Your PyO3 version

0.28

How did you install python? Did you use a virtualenv?

python -m venv

Additional Info

No response

[ngoldbaum]

Any chance you can bisect to find which PyO3 change broke you?

[mikelync]

I don't understand a lot of PyO3 mechanics. But if I were to guess #5708 might be a breaking candidate.
Maybe its author @Tpt can make a comment?

[davidhewitt]

It looks to me like the __qualname__ of the complex enum members is set incorrectly (think it should be ComplexEnum.A):

>>> import pyo3_scratch
>>> pyo3_scratch.ComplexEnum.A
<class 'pyo3_scratch.A'>
>>> pyo3_scratch.ComplexEnum.A.__name__
'A'
>>> pyo3_scratch.ComplexEnum.A.__qualname__
'A'

>>> pyo3_scratch.ComplexEnum.A.__qualname__ = 'ComplexEnum.A'
>>> pyo3_scratch.ComplexEnum.A.__qualname__
'ComplexEnum.A'
>>> pyo3_scratch.ComplexEnum.A
<class 'pyo3_scratch.ComplexEnum.A'>

... will see if I can find a way to fix.

[ravenexp]

I wonder if this will also fix an issue with pdoc dying in infinite recursion trying to generate documentation for v0.28 complex enums. It used to work with v0.27 complex enums. If someone wants to reproduce it, a (possibly empty) .pyi stub file is also required to trigger this bug in pdoc.

I'll try to test the fix in #5796 tomorrow.