Flag useless string expressions in preview

[MichaReiser]

Summary

• Flag standalone string literals and f-strings as B018 in preview mode.
• Preserve attribute docstrings after module/class assignments, PEP 695 type statements, and instance attribute assignments directly in a class-defined __init__.

Closes #11292.

The open question from #11292 is whether this should be a separate rule so that projects using string literals as section separators can enable the remaining B018 checks:

...

"""MAIN"""

if __name__ == "__main__":
    block()

"""AFTER MAIN"""

more()

Test Plan

• Added mdtests for useless string expressions and the relevant docstring exclusions.
• Added focused coverage for PEP 695 type alias docstrings at module and class scope.
• Added focused coverage for __init__ instance attributes, annotated attributes, custom instance-parameter names, rebound receivers, locals, nested assignments, and other methods.
• cargo nextest run -p ruff_linter -p ruff_mdtest (2,837 passed)
• cargo clippy -p ruff_linter --all-targets --all-features -- -D warnings
• cargo dev generate-all
• Repository hooks for the changed files

[astral-sh-bot]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+4357 -1 violations, +0 -0 fixes in 26 projects; 33 projects unchanged)

PostHog/HouseWatch (+2 -0 violations, +0 -0 fixes)

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

+ housewatch/async_migrations/runner.py:19:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ housewatch/clickhouse/backups.py:32:5: useless-expression Found useless expression. Either assign it to a variable or remove it.

PlasmaPy/PlasmaPy (+10 -0 violations, +0 -0 fixes)

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

+ docs/_author_list_from_cff.py:199:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ docs/_global_substitutions.py:223:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ src/plasmapy/formulary/dielectric.py:31:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/diagnostics/charged_particle_radiography/test_synthetic_radiography.py:1008:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/diagnostics/charged_particle_radiography/test_synthetic_radiography.py:883:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/simulation/test_particle_tracker.py:1070:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/simulation/test_particle_tracker.py:837:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/simulation/test_particle_tracker.py:868:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/simulation/test_particle_tracker.py:964:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/simulation/test_particle_tracker.py:996:9: useless-expression Found useless expression. Either assign it to a variable or remove it.

apache/airflow (+71 -0 violations, +0 -0 fixes)

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

+ airflow-core/src/airflow/dag_processing/manager.py:1175:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:146:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:167:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:188:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:214:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:272:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:329:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:362:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:393:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ airflow-core/src/airflow/example_dags/example_asset_partition.py:426:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
... 61 additional changes omitted for project

apache/superset (+37 -0 violations, +0 -0 fixes)

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

+ tests/integration_tests/db_engine_specs/base_engine_spec_tests.py:118:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/integration_tests/db_engine_specs/postgres_tests.py:41:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/integration_tests/query_context_tests.py:1296:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/integration_tests/query_context_tests.py:1348:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/integration_tests/query_context_tests.py:1407:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/integration_tests/query_context_tests.py:1424:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/integration_tests/sqla_models_tests.py:756:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/unit_tests/common/test_process_time_range.py:27:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/unit_tests/common/test_process_time_range.py:36:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/unit_tests/pandas_postprocessing/test_compare.py:121:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
... 27 additional changes omitted for project

binary-husky/gpt_academic (+27 -0 violations, +0 -0 fixes)

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

+ config.py:22:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functional.py:745:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/Document_Conversation.py:199:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/Paper_Reading.py:70:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/game_fns/game_interactive_story.py:125:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/game_fns/game_interactive_story.py:129:13: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/game_fns/game_interactive_story.py:159:13: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/game_fns/game_interactive_story.py:194:13: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/latex_fns/latex_toolbox.py:146:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ crazy_functions/latex_fns/latex_toolbox.py:278:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
... 17 additional changes omitted for project

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

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

+ tests/unit/bokeh/core/test_serialization.py:1056:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ tests/unit/bokeh/embed/test_notebook__embed.py:42:1: useless-expression Found useless expression. Either assign it to a variable or remove it.

demisto/content (+4093 -0 violations, +0 -0 fixes)

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

+ Packs/AHA/Integrations/AHA/AHA.py:103:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AHA/Integrations/AHA/AHA.py:11:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AHA/Integrations/AHA/AHA.py:155:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AHA/Integrations/AHA/AHA.py:228:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AHA/Integrations/AHA/AHA.py:271:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AHA/Integrations/AHA/AHA.py:51:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/AMPv2/AMPv2.py:1162:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/AMPv2/AMPv2.py:16:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/AMPv2/AMPv2.py:3184:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/AMPv2/AMPv2.py:3649:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/AMPv2/AMPv2.py:4:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/CiscoAMPEventCollector/CiscoAMPEventCollector.py:10:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/CiscoAMPEventCollector/CiscoAMPEventCollector.py:197:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/AMP/Integrations/CiscoAMPEventCollector/CiscoAMPEventCollector.py:238:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ANYRUN/Integrations/ANYRUN/ANYRUN.py:16:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ANYRUN/Integrations/ANYRUN/ANYRUN.py:52:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ANYRUN/Integrations/ANYRUN/ANYRUN.py:684:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ANYRUN/Integrations/ANYRUN/ANYRUN.py:6:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ANYRUN/Integrations/ANYRUN/ANYRUN.py:871:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/APIVoid/Integrations/APIVoid/APIVoid.py:13:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/APIVoid/Integrations/APIVoid/APIVoid.py:5:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:115:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:1274:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:139:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:159:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:15:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:2176:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:2208:1: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:222:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:238:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:295:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:32:9: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:353:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:37:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:44:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:521:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:572:13: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:622:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:67:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:698:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:748:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:766:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:774:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:790:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:803:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
+ Packs/ARIAPacketIntelligence/Integrations/ARIAPacketIntelligence/ARIAPacketIntelligence.py:821:5: useless-expression Found useless expression. Either assign it to a variable or remove it.
... 4047 additional changes omitted for project

... Truncated remaining completed project reports due to GitHub comment length restrictions

Changes by rule (2 rules affected)

code	total	+ violation	- violation	+ fix	- fix
useless-expression	4357	4357	0	0	0
unused-noqa	1	0	1	0	0