PyCQA/flake8-bugbear

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A plugin for Flake8 finding likely bugs and design problems in your program. Contains warnings that don't belong in pyflakes and pycodestyle.

Stars: 1.1k
Forks: 123
Open beginner issues: 0
Indexed issues: 52
Avg merge: 2d 5h
Merged PRs (30d): 5

Dominant language: Python
License: MIT
Last GitHub push: Sep 9, 2026
Latest indexed: Sep 19, 2026
Contributing guide: No contributing guide
Code of conduct: No code of conduct
Beginner labels: help wanted

Beginner friendly Everything

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52 open issues indexed

B042 has naive definition of exception Open

Difficulty 3/5 1-2 days Newbie friendliness 42/100

PyCQA/flake8-bugbear#538 · 2 comments · Opened Feb 13, 2026
Proposed rules: encourage use of `re.compile` on constants in module scope, forbid it in function scope Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

PyCQA/flake8-bugbear#536 · Opened Jan 7, 2026
Proposed warning: `assert <generator_expression>` Open

Difficulty 4/5 3-5 days Newbie friendliness 50/100

PyCQA/flake8-bugbear#534 · 3 comments · 2 reactions · Opened Dec 17, 2025
B020 false positives with iterable attribute acess Open

bug help wanted

Difficulty 3/5 1-2 days Newbie friendliness 42/100

PyCQA/flake8-bugbear#521 · Opened Sep 24, 2025
Warn on unnecessary use of `global` Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

PyCQA/flake8-bugbear#492 · 3 comments · Opened Sep 17, 2024
Type annotate code via mypy (strict) typechecking all flake8-bugbear code Open

enhancement help wanted

Difficulty 5/5 Over a week Newbie friendliness 25/100

PyCQA/flake8-bugbear#478 · 4 comments · Opened Jun 24, 2024
B909 has several false positives on black codebase Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#467 · 7 comments · 1 reaction · Opened Apr 22, 2024
How to handle B015 within pytest.raises blocks Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

PyCQA/flake8-bugbear#462 · 3 comments · Opened Feb 22, 2024
B909 improvements Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

PyCQA/flake8-bugbear#454 · 4 comments · 1 reaction · Opened Jan 17, 2024
B018 doesn't trigger for useless expressions involving multiple variables Open

bug help wanted

Difficulty 3/5 1-2 days Newbie friendliness 45/100

PyCQA/flake8-bugbear#452 · 3 comments · 1 reaction · Opened Jan 16, 2024
Couple new rule suggestions Open

enhancement help wanted

Difficulty 5/5 Over a week Newbie friendliness 25/100

PyCQA/flake8-bugbear#440 · 2 comments · Opened Dec 17, 2023
Feature request: a rule for detecting calls to mutate all-caps "constants" Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

PyCQA/flake8-bugbear#423 · 1 comment · 2 reactions · Opened Nov 22, 2023
Policy on bugbears in usage of popular third party libraries Open

help wanted question

Difficulty 5/5 Over a week Newbie friendliness 25/100

PyCQA/flake8-bugbear#414 · 2 comments · Opened Sep 19, 2023
False positive `B023` with loop's local variable Open

Difficulty 3/5 1-2 days Newbie friendliness 48/100

PyCQA/flake8-bugbear#402 · 3 comments · Opened Jul 18, 2023
B023: Why flake8 returns error only for a temporal variable for for loop? Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#396 · 8 comments · Opened Jun 29, 2023
Warn about `dict.fromkeys(keys, mutable)` Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#387 · 3 reactions · Opened May 28, 2023
New check: duplicate types in type hint, or duplicate literals in set Open

enhancement help wanted

Difficulty 4/5 3-5 days Newbie friendliness 42/100

PyCQA/flake8-bugbear#371 · 5 comments · Opened Mar 21, 2023
B006: ignore when type hints suggests immutability. Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

PyCQA/flake8-bugbear#362 · 4 comments · Opened Mar 2, 2023
Proposed warning: reuse of loop variable in nested loop Open

Difficulty 4/5 3-5 days Newbie friendliness 52/100

PyCQA/flake8-bugbear#360 · 4 comments · 1 reaction · Opened Feb 16, 2023
B906 checks all classes, not just AST visitors Open

Difficulty 3/5 1-2 days Newbie friendliness 45/100

PyCQA/flake8-bugbear#359 · Opened Feb 16, 2023
Implement import tracking Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

PyCQA/flake8-bugbear#357 · 4 comments · Opened Feb 15, 2023
B031 flagged on non-itertools groupby Open

enhancement help wanted

Difficulty 3/5 1-2 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#356 · 3 comments · Opened Feb 15, 2023
Report on uncatchable exception handlers (?) Open

enhancement help wanted

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#349 · 3 comments · Opened Feb 7, 2023
Question: B027 empty method in an abstract base class Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

PyCQA/flake8-bugbear#301 · 3 comments · 3 reactions · Opened Oct 25, 2022
`B950` ignores `max-doc-length` flake8 configuration option Open

enhancement help wanted

Difficulty 3/5 1-2 days Newbie friendliness 42/100

PyCQA/flake8-bugbear#285 · 3 comments · Opened Sep 18, 2022
Enforce order of decorators combined with `@abstractmethod` Open

enhancement help wanted

Difficulty 3/5 1-2 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#279 · 1 comment · Opened Aug 26, 2022
New rule to catch multidimensional array multiplication Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#271 · 1 comment · Opened Jul 13, 2022
B950 does not give warnings when --extend-ignore'ing E501 Open

bug help wanted terrible_maintainer

Difficulty 4/5 3-5 days Newbie friendliness 32/100

PyCQA/flake8-bugbear#266 · 6 comments · Opened Jun 23, 2022
Tech Debt: Cleanup `should_warn` and rely on extend-select (+ maybe delete load_file) Open

bug enhancement help wanted

Difficulty 3/5 1-2 days Newbie friendliness 28/100

PyCQA/flake8-bugbear#260 · 2 comments · 1 reaction · Opened Jun 10, 2022
B006: Case where mutable default arguments are not detected Open

bug help wanted

Difficulty 4/5 3-5 days Newbie friendliness 30/100

PyCQA/flake8-bugbear#253 · 5 comments · Opened Apr 10, 2022
B008: extend-immutable-calls does not work with imported function Open

bug enhancement help wanted

Difficulty 4/5 3-5 days Newbie friendliness 58/100

PyCQA/flake8-bugbear#252 · 10 comments · 1 reaction · Opened Apr 4, 2022
Detect: 'variable_name' in the try block with 'except ImportError' should also be defined in the except block Open

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#224 · 2 comments · Opened Mar 1, 2022
`extend-ignore` and `extend-select` options seem to be ignored Open

bug help wanted

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#221 · 8 comments · 2 reactions · Opened Jan 30, 2022
Loop variable use in closure not considered Open

enhancement help wanted

Difficulty 3/5 1-2 days Newbie friendliness 42/100

PyCQA/flake8-bugbear#175 · 1 comment · Opened Jul 11, 2021
Proposed Check: Flag Improper Use of string.find() Open

enhancement help wanted

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#170 · 3 comments · Opened May 22, 2021
Proposed Check: Unintentional str concat Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

PyCQA/flake8-bugbear#156 · 2 comments · Opened Feb 4, 2021
Possible false positive for B015 Open

Difficulty 4/5 3-5 days Newbie friendliness 25/100

PyCQA/flake8-bugbear#152 · 4 comments · 5 reactions · Opened Dec 18, 2020
raise RunetimeError check Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#143 · 4 comments · Opened Oct 17, 2020
How about checking that you're not using a list for an in? Open

enhancement

Difficulty 4/5 3-5 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#139 · 2 comments · Opened Oct 6, 2020
Assertion check fails on syntactically-valid Python code Open

help wanted

Difficulty 3/5 1-2 days Newbie friendliness 42/100

PyCQA/flake8-bugbear#138 · 4 comments · Opened Oct 5, 2020
Suggestion: Ignore B006 if the variable in question is immediately copied Open

Difficulty 5/5 Over a week Newbie friendliness 35/100

PyCQA/flake8-bugbear#137 · 14 comments · 2 reactions · Opened Sep 15, 2020
Proposed opinionated warning against re.match Open

help wanted question

Difficulty 4/5 3-5 days Newbie friendliness 25/100

PyCQA/flake8-bugbear#132 · 1 comment · Opened Aug 13, 2020
B306 should ignore cases where BaseException subclass defines message property Open

Difficulty 3/5 1-2 days Newbie friendliness 38/100

PyCQA/flake8-bugbear#131 · 1 comment · 4 reactions · Opened Jul 16, 2020
Proposed check: ambiguous variable names Open

Difficulty 5/5 Over a week Newbie friendliness 28/100

PyCQA/flake8-bugbear#123 · Opened Jun 11, 2020
Mutable module level variables Open

Difficulty 5/5 Over a week Newbie friendliness 30/100

PyCQA/flake8-bugbear#118 · 2 comments · 1 reaction · Opened Feb 24, 2020
Error message for B005 is not precise enough Open

Difficulty 2/5 1-3 hours Newbie friendliness 35/100

PyCQA/flake8-bugbear#91 · 1 comment · 5 reactions · Opened Oct 2, 2019
Proposed Check: variable used outside of for-loop scope Open

Difficulty 5/5 Over a week Newbie friendliness 25/100

PyCQA/flake8-bugbear#79 · 2 comments · 13 reactions · Opened Jul 8, 2019
B011 is misleading, and the advice doesn't sound good Open

Difficulty 3/5 1-2 days Newbie friendliness 35/100

PyCQA/flake8-bugbear#66 · 17 comments · 8 reactions · Opened Mar 31, 2019
B903 reword message when a subclass is involved Open

Difficulty 2/5 1-3 hours Newbie friendliness 45/100

PyCQA/flake8-bugbear#63 · 7 comments · 6 reactions · Opened Mar 19, 2019
B305 triggered for methods in regular objects Open

Difficulty 3/5 1-2 days Newbie friendliness 38/100

PyCQA/flake8-bugbear#59 · 4 comments · Opened Feb 13, 2019

PyCQA/flake8-bugbear

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