Fix false-negative for used-before-assignment with postponed evaluation in function defs

[cdce8p]

Description

used-before-assignment errors should still be emitted for function arg defaults even with postponed evaluation of type annotations enabled.

from __future__ import annotations

def func(var = A):  # should emit 'used-before-assignment'
    ...

class A: ...

Didn't add a test case for it since the test suite already includes examples for it. These will be tested with Python 3.14 where the deferred evaluation of type annotations will be the default.

pylint/tests/functional/u/undefined/undefined_variable.py

Lines 91 to 96 in 9e72867

	def test_arguments(arg=TestClass): # [used-before-assignment]
	""" TestClass isn't defined yet. """
	return arg
	class TestClass(Ancestor): # [used-before-assignment]
	""" contains another class, which uses an undefined ancestor. """

pylint/tests/functional/u/undefined/undefined_variable.py

Lines 142 to 147 in 9e72867

	enable = True
	def test(self, is_enabled=enable):
	"""do nothing."""
	def test1(self, is_enabled=enabled): # [used-before-assignment]
	"""enabled is undefined at this point, but it is used before assignment."""

--
This does address some of the issues in #10467. In particular

FAILED tests/test_functional.py::test_functional[undefined_variable]
    - AssertionError: Wrong message(s) raised for "undefined_variable.py":

Expected in testdata:
  91: used-before-assignment (times 1)
 146: used-before-assignment (times 1)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.86%. Comparing base (44740e5) to head (aaf9192).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #10482   +/-   ##
=======================================
  Coverage   95.86%   95.86%           
=======================================
  Files         176      176           
  Lines       19164    19168    +4     
=======================================
+ Hits        18372    18376    +4     
  Misses        792      792           

Files with missing lines	Coverage Δ
pylint/checkers/variables.py	97.30% <ø> (+<0.01%)	⬆️

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[github-actions]

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

This comment was generated for commit aaf9192

[Pierre-Sassoulas]

I was generating the release note for 3.3.8 and realized that there is this false negative we backported. Not a candidate for a backport normally. I missed that during review (on mobile labels are not shown by default) and I'm feeling like not reverting. Thoughts ?

[cdce8p]

I was generating the release note for 3.3.8 and realized that there is this false negative we backported. Not a candidate for a backport normally. I missed that during review (on mobile labels are not shown by default) and I'm feeling like not reverting. Thoughts ?

Missed that as well. The impact from the change here should be fairly minimal. All errors uncovered here would crash during normal execution so it should probably be fine. It also only applies to files which have the from __future__ import annotation import in the first place.