False positive undefined-variable when a function attribute of same name is set

[Lucas-C]

Steps to reproduce

CONDITION = None
FUNC = lambda: CONDITION
FUNC.CONDITION = 42

Pylint output:

pylint_bug_repro.py:2:15: E0602: Undefined variable 'CONDITION' (undefined-variable)

Current behavior

An "undefined variable" is incorrectly reported.

Expected behavior

Zero issue detected when defining a function attribute
with the same name of a local variable in the current scope.

pylint --version output

$ pylint --version
pylint 2.6.0
astroid 2.4.2
Python 3.7.7 (default, Apr 10 2020, 07:59:19)
[GCC 9.3.0]

Additional notes

There are a few other existing issues related to "false positive undefined-variable" errors:

• Undefined variable false report in list/dict comprehension in formatstr #2491
• False positive for undefined variable with assignment expression #3688
• False positive undefined-variable when variable name in decoration matches function argument #3791

[hippo91]

@Lucas-C thanks for this clear report!

[Lucas-C]

Thanks for the fix @Pierre-Sassoulas !

[Pierre-Sassoulas]

I just reviewed ; @DanielNoord did the actual work 😉