[pylint] Implement assigning-non-slot (E0237)

[tsugumi-sys]

Summary

Implement assigning-non-slot / E0237

related #970

Test Plan

cargo test

[github-actions]

ruff-ecosystem results

Linter (stable)

ℹ️ ecosystem check detected linter changes. (+2 -0 violations, +0 -0 fixes in 1 projects; 42 projects unchanged)

DisnakeDev/disnake (+2 -0 violations, +0 -0 fixes)

+ disnake/embeds.py:206:9: PLE0237 Attribute `timestamp` is not defined in class's `__slots__`
+ disnake/embeds.py:214:9: PLE0237 Attribute `colour` is not defined in class's `__slots__`

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
PLE0237	2	2	0	0	0

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+2 -0 violations, +0 -0 fixes in 1 projects; 42 projects unchanged)

DisnakeDev/disnake (+2 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --preview

+ disnake/embeds.py:206:9: PLE0237 Attribute `timestamp` is not defined in class's `__slots__`
+ disnake/embeds.py:214:9: PLE0237 Attribute `colour` is not defined in class's `__slots__`

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
PLE0237	2	2	0	0	0

[charliermarsh]

How does Pylint handle this for subclasses? E.g., does it allow items in __slots__ that are attributes on superclasses?

[tsugumi-sys]

@charliermarsh

If subclasses define slots, pylint checks not redefining the same slots as its superclass in redefined-slots-in-subclass / W0244.

Also we can set new slots in the superclass and pylint checks it in assigning-non-slot / E0237.

[charliermarsh]

Thanks @tsugumi-sys, I limited the rule to classes that don't inherit from "unknown" parent classes for now.

We actually have support for resolving parent classes within the same file, so we could extend the rule to check that.