[`flake8-bugbear`] Implement `delattr-with-constant` (`B043`) by Bortlesboat · Pull Request #23737 · astral-sh/ruff

Bortlesboat · 2026-03-05T12:39:25Z

Summary

Implements B043 from flake8-bugbear, which flags delattr() calls where the attribute name is a constant string literal (e.g., delattr(obj, "foo")). These should use del obj.foo instead.

The implementation follows the same pattern as the existing B009 (getattr) and B010 (setattr) rules:

Checks that the attribute name is a valid Python identifier
Skips __debug__ (deleting it is a SyntaxError)
Skips mangled private names
Marks fixes as unsafe for non-NFKC attribute names and expressions containing comments
Only applies the fix when the delattr call is used as a standalone statement

Partially addresses #3758.

Test plan

Added test fixture B043.py covering valid usage, invalid usage, starred args, NFKC safety, comments, and builtins.delattr.

Implement B043 from flake8-bugbear, which flags `delattr()` calls with constant string attribute arguments. These can be replaced with `del` statements for better readability. The implementation mirrors the existing B009 (getattr) and B010 (setattr) rules, including NFKC normalization safety checks and __debug__ handling. Closes #3758 (partially)

ntBre · 2026-03-05T13:45:10Z

Thanks! I'll leave the review to Amy but I was curious about historical issues, and this will close #18338, which links to the upstream implementation: PyCQA/flake8-bugbear#514. So I think it seems okay for us to add it too.

crates/ruff_linter/src/rules/flake8_bugbear/rules/delattr_with_constant.rs

astral-sh-bot · 2026-03-05T13:53:32Z

`ruff-ecosystem` results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+21 -0 violations, +0 -0 fixes in 6 projects; 50 projects unchanged)

apache/airflow (+11 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview --select ALL

+ providers/common/io/tests/unit/common/io/operators/test_file_transfer.py:78:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ providers/common/io/tests/unit/common/io/operators/test_file_transfer.py:80:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ providers/openlineage/tests/unit/openlineage/plugins/test_listener.py:1665:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ providers/openlineage/tests/unit/openlineage/plugins/test_listener.py:1872:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ providers/yandex/tests/unit/yandex/hooks/test_yandex.py:146:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ shared/configuration/tests/configuration/test_parser.py:388:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ shared/configuration/tests/configuration/test_parser.py:390:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ task-sdk/src/airflow/sdk/execution_time/supervisor.py:1762:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ task-sdk/src/airflow/sdk/execution_time/supervisor.py:1769:17: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ task-sdk/tests/task_sdk/execution_time/test_supervisor.py:2681:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ task-sdk/tests/task_sdk/execution_time/test_supervisor.py:2684:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.

apache/superset (+5 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview --select ALL

+ superset/commands/chart/warm_up_cache.py:76:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ superset/utils/core.py:1505:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ tests/integration_tests/dao/base_dao_test.py:87:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ tests/integration_tests/utils_tests.py:344:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ tests/unit_tests/common/test_query_context_processor.py:515:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.

bokeh/bokeh (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview --select ALL

+ src/bokeh/core/has_props.py:723:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.

model-bakers/model_bakery (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview

+ tests/test_filling_fields.py:62:9: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.

rotki/rotki (+2 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview

+ rotkehlchen/tests/conftest.py:116:13: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.
+ rotkehlchen/tests/unit/test_utils.py:220:5: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.

zulip/zulip (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --no-fix --output-format concise --preview --select ALL

+ confirmation/migrations/0016_realmcreationkey_to_realmcreationstatus.py:92:17: B043 [*] Do not call `delattr` with a constant attribute value. It is not any safer than normal property deletion.

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
B043	21	21	0	0	0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

amyreese

Thank you for working on this

crates/ruff_linter/src/rules/flake8_bugbear/rules/delattr_with_constant.rs

- Move semantic builtin check to top for early exit - Combine args destructuring into single let - Extract attr_name earlier and use throughout - Merge guard conditions into single conditional - Use Fix::applicable_edit with Applicability enum - Rename helper to generate_del_statement and move below rule

astral-sh-bot bot assigned amyreese Mar 5, 2026

astral-sh-bot bot requested a review from amyreese March 5, 2026 12:39

ntBre added rule Implementing or modifying a lint rule preview Related to preview mode features labels Mar 5, 2026

ntBre reviewed Mar 5, 2026

View reviewed changes

crates/ruff_linter/src/rules/flake8_bugbear/rules/delattr_with_constant.rs Outdated Show resolved Hide resolved

ntBre linked an issue Mar 5, 2026 that may be closed by this pull request

New rule del-attr-with-constant #18338

Closed

fix: use preview_since annotation per review

df601e5

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

amyreese requested changes Mar 6, 2026

View reviewed changes

amyreese approved these changes Mar 7, 2026

View reviewed changes

Bortlesboat and others added 2 commits March 7, 2026 10:20

Fix cargo fmt formatting

6234133

Add snapshot

6c00b6f

amyreese changed the title ~~[flake8-bugbear] Implement delattr-with-constant (B043)~~ [flake8-bugbear] Implement delattr-with-constant (B043) Mar 9, 2026

amyreese enabled auto-merge (squash) March 9, 2026 19:37

Update schema

5dc1b7f

amyreese merged commit be5db3c into astral-sh:main Mar 9, 2026
42 checks passed

BrewTestBot mentioned this pull request Mar 12, 2026

ruff 0.15.6 Homebrew/homebrew-core#272048

Merged

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[`flake8-bugbear`] Implement `delattr-with-constant` (`B043`)#23737

[`flake8-bugbear`] Implement `delattr-with-constant` (`B043`)#23737
amyreese merged 6 commits intoastral-sh:mainfrom
Bortlesboat:implement-b043-delattr-with-constant

Bortlesboat commented Mar 5, 2026

Uh oh!

ntBre commented Mar 5, 2026

Uh oh!

Uh oh!

astral-sh-bot bot commented Mar 5, 2026 •

edited

Loading

Uh oh!

amyreese left a comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

Conversation

Bortlesboat commented Mar 5, 2026

Summary

Test plan

Uh oh!

ntBre commented Mar 5, 2026

Uh oh!

Uh oh!

astral-sh-bot bot commented Mar 5, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

ruff-ecosystem results

Linter (stable)

Linter (preview)

Uh oh!

amyreese left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

3 participants

astral-sh-bot bot commented Mar 5, 2026 •

edited

Loading

`ruff-ecosystem` results