Fix used-before-assignment false positive for walrus operators in ifs

[zenlyj]

Type of Changes

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

Description

After investigation, there seems to be two main cases that trigger used-before-assignment false positives:

1. Ternary expression with walrus operator within attribute calls. Eg. (foo if (foo:='foo') else 'bar').upper()
2. Ternary expression with walrus operator nested in function calls. Eg. str(str(foo if (foo:='foo') else 'bar'))

This fix enforces a stricter check on whether a name may be assigned and used in the same statement.

Closes #7779

[Pierre-Sassoulas]

Maybe a simplification with early return ?

[mbyrnepr2]

@zenlyj the changelog file is required. There are a number here if you need to check how that is done

[mbyrnepr2]

@zenlyj The Python 3.7 test in the CI is failing because Walrus is a syntax-error. It's possible to run this test for Python versions greater than 3.7. There are many examples in the existing functional tests where a .rc file, similar to this one, is added with the same file-name as the functional test module, for the tests to be run for the specification in the .rc file.

[codecov]

Codecov Report

Merging #8029 (cad42be) into main (89a20e2) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #8029   +/-   ##
=======================================
  Coverage   95.42%   95.42%           
=======================================
  Files         176      176           
  Lines       18525    18527    +2     
=======================================
+ Hits        17678    17680    +2     
  Misses        847      847           

Impacted Files	Coverage Δ
pylint/checkers/variables.py	97.38% <100.00%> (+<0.01%)	⬆️

[zenlyj]

@mbyrnepr2 Thank you for helping with the CI fails, very helpful advice.

[github-actions]

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

This comment was generated for commit cad42be

[Pierre-Sassoulas]

Thank you for the fix, the test cases are pretty nice too. This will be available in 2.15.10 :)