regex for ignoring hidden directories doesn't work as expected

[tbennett0]

Bug description

In running pylint --recursive y . to ignore hidden directories using 2.14.4, I discovered the following pattern works:

[tool.pylint.MASTER]
ignore-paths = [
  "^.local/.*$"
]

but this one doesn't:

[tool.pylint.MASTER]
ignore-paths = [
  "^\\.local/.*$"
]

I would expect that the regex would see . as any character, so it matches the first, but explicitly using an escaped period that should also match doesn't cause that path to be ignored.

Configuration

% cat .local/test.py
import blam

Command used

% pylint --recursive=y .

Pylint output

************* Module test
.local/test.py:1:0: C0114: Missing module docstring (missing-module-docstring)
.local/test.py:1:0: E0401: Unable to import 'blam' (import-error)
.local/test.py:1:0: W0611: Unused import blam (unused-import)

Expected behavior

No output on both examples.

Pylint version

pylint 2.14.4
astroid 2.11.6
Python 3.9.12 (main, Jun 27 2022, 13:42:07)
[Clang 13.1.6 (clang-1316.0.21.2.5)]

OS / Environment

No response

Additional dependencies

No response

[tbennett0]

@matusvalo this is possibly related to #6964. Thanks!

[matusvalo]

@tbennett0 could you verify the issue with the main branch whether it fixes the issue?

[DanielNoord]

@matusvalo 2.14.4 was just released, which included your fix for #6964. So this seems to be a regression after that fix was applied.

[matusvalo]

OK I have misread the issue. So I need to fix the fix of the fix :-/. OK I am sorry for that. Doing recursive linting seems to be not so trivial as looked in the first place :-/

[matusvalo]

OK, I have investigated issue. It seems that the issue has root cause in parameter parsing rather then in recursive logic:

1. fix of False positive no-value-for-parameter for Qt methods #6464 is already fixing first case ("^.local/.*$") - can be easily checked, 2.14.3 version of pylint ignores the regex
2. For the case "^\\.local/.*$", I put breakpoint in the line https://github.com/PyCQA/pylint/blob/018176d48b5608bdbc2ef9a8d09b0cae7a83da33/pylint/lint/expand_modules.py#L57 which gives me following:

(Pdb) p element
'.local/test.py'
(Pdb) p ignore_list_paths_re
[re.compile('^\\\\.local\\\\.*$|^/.local/.*$')]
(Pdb) ignore_list_paths_re[0].match(element)

ignore_list_paths_re is not matched due \\\\ part which does not match the input. The cause of different patterns seems following portion of the code:
https://github.com/PyCQA/pylint/blob/018176d48b5608bdbc2ef9a8d09b0cae7a83da33/pylint/config/argument.py#L110-L121

It seems like managing path delimiter in windows, but I am not 100% confident with this part of pylint. @DanielNoord could you give me a hint?

[DanielNoord]

Ah yeah. This is a duplicate of #5398.

[matusvalo]

OK so I am closing it as duplicate.