Warning filter message/module documentation is misleading

[kevinoid]

BPO	42272
Nosy	@kevinoid
PRs	bpo-42272: fix misleading warning filter message/module docs #23172

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2020-11-05.20:06:37.165>
labels = ['type-feature', '3.10', 'docs']
title = 'Warning filter message/module documentation is misleading'
updated_at = <Date 2021-08-28.08:27:10.953>
user = 'https://github.com/kevinoid'

bugs.python.org fields:

activity = <Date 2021-08-28.08:27:10.953>
actor = 'ananyadatta88'
assignee = 'docs@python'
closed = False
closed_date = None
closer = None
components = ['Documentation']
creation = <Date 2020-11-05.20:06:37.165>
creator = 'kevinoid'
dependencies = []
files = ['50238']
hgrepos = []
issue_num = 42272
keywords = ['patch']
message_count = 2.0
messages = ['380429', '400464']
nosy_count = 3.0
nosy_names = ['docs@python', 'kevinoid', 'ananyadatta88']
pr_nums = ['23172']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue42272'
versions = ['Python 3.10']

[kevinoid]

"The Warnings Filter" section of the documentation for the warnings module describes the message and module filters as "a string containing a regular expression". While that is true when they are arguments to the filterwarnings function, it is not true when they appear in -W or $PYTHONWARNINGS where they are matched literally (after stripping any starting/ending whitespace).

Additionally, in the "Describing Warning Filters" section, the example "error:::mymodule[.*]" does not behave as described. If it were used as an argument to filterwarnings, where it would be treated as a regular expression, it would match the (invalid) module names mymodule. or mymodule* while it would match mymodule[.*] literally if passed via -W or $PYTHONWARNINGS.

[ananyadatta88]

No comments

[ezio-melotti]

Fixed in GH-23172, backported in GH-93342 and GH-93341. Thanks for the report and the PR!

[kevinoid]

Thanks for reviewing and merging it @ezio-melotti!