False-positive I0021: Useless suppression of 'line-too-long' (useless-suppression)

[bersbersbers]

Steps to reproduce

Given a file a.py:

"""False-positive I0021: Useless suppression of 'line-too-long' (useless-suppression)"""
VAR = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"  # pylint:disable=line-too-long

Current behavior

Result of pylint --enable=useless-suppression a.py:

************* Module a
a.py:2:0: I0021: Useless suppression of 'line-too-long' (useless-suppression)

--------------------------------------------------------------------
Your code has been rated at 10.00/10 (previous run: 10.00/10, +0.00)

Expected behavior

No output.

pylint --version output

Result of pylint --version output:

pylint 2.7.2
astroid 2.5.1
Python 3.8.8 (default, Feb 22 2021, 14:04:38) 
[GCC 7.5.0]

[Pierre-Sassoulas]

I can reproduce this, thank you.

[bersbersbers]

Here's another example:

"""False-positive ungrouped-imports or useless-suppression."""
from re import sub

if 2 > 1:
    from pathlib import Path

    if 3 > 1:
        from re import match  # pylint:disable=ungrouped-imports


print(Path(), sub("", "", ""), match("", ""))

Assuming that ungrouped-imports, there is a false-positive useless-suppression. (Otherwise, there is a false-positive ungrouped-imports.)

[Pierre-Sassoulas]

Hi @bersbersbers in your example the import are grouped each in their own scope (isort would not change the file) so there should not be an ungrouped-imports and the useles suppression is not a false positive.

[bersbersbers]

Agreed. I found #2366 which is another false-positive of useless-suppression, but I also filed #4360 for the false-positive ungrouped-imports.

[Pierre-Sassoulas]

Another example I just encountered in astroid:

************* Module astroid.node_classes
astroid/node_classes.py:864:0: I0021: Useless suppression of 'unused-variable' (useless-suppression)

        # pylint: disable=unused-variable; doesn't understand singledispatch
        @_repr_tree.register(NodeNG)
        def _repr_node(node, result, done, cur_indent="", depth=1):
            """Outputs a strings representation of an astroid node."""

If you remove the disable you then get astroid/node_classes.py:864:8: W0612: Unused variable '_repr_node' (unused-variable)

[DanielNoord]

Another example I just encountered in astroid:

************* Module astroid.node_classes
astroid/node_classes.py:864:0: I0021: Useless suppression of 'unused-variable' (useless-suppression)

       # pylint: disable=unused-variable; doesn't understand singledispatch
       @_repr_tree.register(NodeNG)
       def _repr_node(node, result, done, cur_indent="", depth=1):
           """Outputs a strings representation of an astroid node."""

If you remove the disable you then get astroid/node_classes.py:864:8: W0612: Unused variable '_repr_node' (unused-variable)

This is a different issue and a different issue should be opened to track it. If you can give me a minimal working example to include in the tests I can work on fixing the false positive!