Fix a crash for Enum class decorated with dataclass

[mbyrnepr2]

Type of Changes

	Type
✓	🐛 Bug fix
	✨ New feature
	🔨 Refactoring
	📜 Docs

Description

Fix a crash when an enum class which is also decorated with a dataclasses.dataclass decorator is defined.

Closes #9100

[codecov]

Codecov Report

Merging #9104 (fc62a9d) into main (f74200d) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9104   +/-   ##
=======================================
  Coverage   95.75%   95.75%           
=======================================
  Files         173      173           
  Lines       18663    18665    +2     
=======================================
+ Hits        17871    17873    +2     
  Misses        792      792           

Files	Coverage Δ
pylint/checkers/utils.py	95.94% <100.00%> (+<0.01%)	⬆️

[Pierre-Sassoulas]

Maybe we could add the functional test for the false negative we create (something that should return true ?) and a todo that we'll fix in 3.1 ?

[mbyrnepr2]

Ok once I create the astroid issue I'll update the doc-string of the test class with the issue number.

[DanielNoord]

Thanks for picking this up!

[DanielNoord]

Shall we do a check if the get returns None? In the future I think we will ask ourselves what kind of error we are catching here whereas seeing an is not None check is very explicit.

[mbyrnepr2]

I went for try/except since in the majority of cases this code is run, there should be a __members__ present; the only case I know of where it breaks currently, is when the dataclass decorator is used.
You make a good point though - at first glance it would be a bit difficult to see where the cause of the exception is. We could simplify it:

+    members = frame.locals.get("__members__")
     try:
-        enum_member_objects = frame.locals.get("__members__")[0].items
+        enum_member_objects = members[0].items
     except TypeError:
         return False
     return node.name in [name_obj.name for value, name_obj in enum_member_objects]

Or your suggestion:

 
-    try:
-        enum_member_objects = frame.locals.get("__members__")[0].items
-    except TypeError:
-        return False
-    return node.name in [name_obj.name for value, name_obj in enum_member_objects]
+    members = frame.locals.get("__members__")
+    if members is not None:
+        enum_member_objects = members[0].items
+        return node.name in [name_obj.name for value, name_obj in enum_member_objects]
+    return False

[DanielNoord]

I prefer the second diff, but perhaps with an early exit for if members is None and then doing the rest of the checks.

We can just add a comment saying that "due to unforeseen circumstances members is not always present" 😄

[github-actions]

🤖 According to the primer, this change has no effect on the checked open source code. 🤖🎉

This comment was generated for commit fc62a9d

[Pierre-Sassoulas]

Great PR !