Remove support for `__cached__` and `__package__` if missing corresponding `__spec__` attributes

[picnixz]

Feature or enhancement

Setting __cached__ or __package__ on a module while failing to set the corresponding __spec__ attributes is deprecated since Python 3.12 (see #97879).

cc @brettcannon

[mkaraev]

@picnixz is this issue good for a first-time contribution? If so, maybe I could try to help with it?

[picnixz]

No it's not good for a first-time contribution. For first-time contribution, please look at "easy" labels

[xuantengh]

Hi I'd like to work on this. Does it mean for modules without __spec__, we do not set __cached__ nor __package__ for them?

[picnixz]

No my bad, the title is misleading :') it's only if setting the attribute on __spec__ failed that we would not allow setting it otherwise. The exact description is in pending-removal-in-315 but I would like the feedback from an importlib expert.

[brettcannon]

FYI __package__ and __cached__ are slated for removal in 3.15 (although being slated for removal doesn't mean Barry and I will get to it at the core dev sprints which is our traditional time to try and remove those attributes 😅).

[serhiy-storchaka]

It cannot be done now, because the deprecation was not complete. The warnings were emitted not in all cases. See #122255.

We first need to start emitting deprecation warnings in all cases, this will restart the deprecation period.

[picnixz]

Oh. So let's first remove the different mentions to this removal (I haven't worked at all on this one because I didn't know what to do and how to do it as well) maybe?