[ruff] Empty branches (RUF050)

[InSyncWithFoo]

Summary

Resolves #13929 and #9472.

Test Plan

cargo nextest run and cargo insta test.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+286 -0 violations, +0 -0 fixes in 18 projects; 37 projects unchanged)

RasaHQ/rasa (+4 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ rasa/shared/core/generator.py:244:13: RUF050 Empty code branch
+ rasa/shared/core/training_data/story_reader/yaml_story_reader.py:294:9: RUF050 Empty code branch
+ tests/nlu/extractors/test_mitie_entity_extractor.py:102:9: RUF050 Empty code branch
+ tests/shared/nlu/training_data/test_features.py:432:9: RUF050 Empty code branch

apache/airflow (+30 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ airflow/api_connexion/endpoints/pool_endpoint.py:104:9: RUF050 Empty code branch
+ airflow/api_fastapi/core_api/routes/public/pools.py:131:9: RUF050 Empty code branch
+ airflow/models/dag.py:1187:9: RUF050 Empty code branch
+ airflow/models/dag.py:1761:9: RUF050 Empty code branch
+ airflow/models/dagrun.py:1353:17: RUF050 Empty code branch
+ airflow/serialization/serialized_objects.py:1393:13: RUF050 Empty code branch
+ airflow/serialization/serialized_objects.py:1757:13: RUF050 Empty code branch
+ dev/chart/build_changelog_annotations.py:94:9: RUF050 Empty code branch
+ providers/src/airflow/providers/amazon/aws/executors/ecs/ecs_executor.py:161:13: RUF050 Empty code branch
+ providers/src/airflow/providers/amazon/aws/triggers/eks.py:151:17: RUF050 Empty code branch
... 20 additional changes omitted for project

apache/superset (+6 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ superset/commands/dataset/importers/v0.py:282:13: RUF050 Empty code branch
+ superset/daos/chart.py:30:1: RUF050 Empty code branch
+ superset/db_engine_specs/gsheets.py:358:13: RUF050 Empty code branch
+ superset/models/helpers.py:1764:17: RUF050 Empty code branch
+ superset/utils/log.py:37:1: RUF050 Empty code branch
+ tests/integration_tests/datasource_tests.py:119:9: RUF050 Empty code branch

bokeh/bokeh (+5 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ src/bokeh/command/subcommands/serve.py:884:9: RUF050 Empty code branch
+ src/bokeh/plotting/_renderer.py:282:17: RUF050 Empty code branch
+ src/bokeh/plotting/_renderer.py:284:17: RUF050 Empty code branch
+ src/bokeh/plotting/_renderer.py:286:17: RUF050 Empty code branch
+ src/bokeh/plotting/_renderer.py:288:17: RUF050 Empty code branch

ibis-project/ibis (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ ibis/common/deferred.py:393:9: RUF050 Empty code branch

lnbits/lnbits (+6 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ lnbits/core/crud.py:783:5: RUF050 Empty code branch
+ lnbits/core/crud.py:791:5: RUF050 [*] Empty code branch
+ lnbits/core/crud.py:794:5: RUF050 Empty code branch
+ lnbits/core/crud.py:800:5: RUF050 [*] Empty code branch
+ lnbits/wallets/nwc.py:579:13: RUF050 Empty code branch
+ tests/helpers.py:52:5: RUF050 Empty code branch

pandas-dev/pandas (+109 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ asv_bench/benchmarks/frame_methods.py:162:9: RUF050 Empty code branch
+ asv_bench/benchmarks/frame_methods.py:176:9: RUF050 Empty code branch
+ asv_bench/benchmarks/frame_methods.py:192:9: RUF050 Empty code branch
+ asv_bench/benchmarks/frame_methods.py:208:9: RUF050 Empty code branch
+ asv_bench/benchmarks/frame_methods.py:224:9: RUF050 Empty code branch
+ asv_bench/benchmarks/frame_methods.py:234:9: RUF050 Empty code branch
+ asv_bench/benchmarks/index_object.py:101:9: RUF050 Empty code branch
+ asv_bench/benchmarks/index_object.py:97:9: RUF050 Empty code branch
+ asv_bench/benchmarks/io/csv.py:497:9: RUF050 Empty code branch
+ asv_bench/benchmarks/series_methods.py:370:9: RUF050 Empty code branch
+ asv_bench/benchmarks/strings.py:283:9: RUF050 Empty code branch
+ asv_bench/benchmarks/timeseries.py:138:9: RUF050 Empty code branch
+ pandas/_testing/asserters.py:1009:9: RUF050 Empty code branch
+ pandas/_testing/asserters.py:129:13: RUF050 Empty code branch
+ pandas/_testing/asserters.py:132:13: RUF050 Empty code branch
+ pandas/_testing/asserters.py:1406:5: RUF050 Empty code branch
+ pandas/core/arrays/arrow/array.py:616:13: RUF050 Empty code branch
+ pandas/core/arrays/datetimelike.py:2002:9: RUF050 Empty code branch
+ pandas/core/arrays/datetimelike.py:2269:9: RUF050 Empty code branch
... 90 additional changes omitted for project

pypa/cibuildwheel (+2 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ cibuildwheel/pyodide.py:406:5: RUF050 [*] Empty code branch
+ test/utils.py:29:1: RUF050 Empty code branch

python-poetry/poetry (+2 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ src/poetry/puzzle/provider.py:240:9: RUF050 Empty code branch
+ src/poetry/utils/shell.py:129:9: RUF050 Empty code branch

reflex-dev/reflex (+4 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ reflex/base.py:35:13: RUF050 Empty code branch
+ reflex/utils/processes.py:298:5: RUF050 Empty code branch
+ tests/units/test_app.py:1195:5: RUF050 Empty code branch
+ tests/units/test_state.py:2076:9: RUF050 Empty code branch

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

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ rotkehlchen/data_import/importers/nexo.py:155:9: RUF050 Empty code branch
+ rotkehlchen/icons.py:32:1: RUF050 Empty code branch

scikit-build/scikit-build-core (+1 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ tests/test_cmake_ast.py:137:5: RUF050 Empty code branch

zulip/zulip (+35 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview --select ALL

+ analytics/views/stats.py:67:9: RUF050 Empty code branch
+ tools/lib/provision_inner.py:291:13: RUF050 Empty code branch
+ zerver/data_import/slack_message_conversion.py:241:5: RUF050 Empty code branch
+ zerver/decorator.py:80:5: RUF050 Empty code branch
+ zerver/lib/event_schema.py:270:5: RUF050 Empty code branch
+ zerver/lib/events.py:1375:9: RUF050 Empty code branch
+ zerver/lib/events.py:1517:5: RUF050 Empty code branch
+ zerver/lib/events.py:1520:5: RUF050 Empty code branch
+ zerver/lib/events.py:1523:5: RUF050 Empty code branch
+ zerver/lib/events.py:1526:5: RUF050 Empty code branch
... 25 additional changes omitted for project

indico/indico (+9 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ indico/cli/devserver.py:231:9: RUF050 Empty code branch
+ indico/core/celery/controllers.py:25:13: RUF050 Empty code branch
+ indico/modules/designer/pdf.py:155:17: RUF050 Empty code branch
+ indico/modules/events/api.py:620:13: RUF050 Empty code branch
+ indico/modules/events/export.py:384:17: RUF050 Empty code branch
+ indico/modules/logs/util.py:54:9: RUF050 Empty code branch
+ indico/testing/util.py:99:5: RUF050 Empty code branch
+ indico/util/string.py:87:13: RUF050 Empty code branch
+ indico/web/flask/app.py:171:5: RUF050 Empty code branch

python-trio/trio (+10 -0 violations, +0 -0 fixes)

ruff check --no-cache --exit-zero --ignore RUF9 --output-format concise --preview

+ src/trio/_core/_io_kqueue.py:198:17: RUF050 Empty code branch
+ src/trio/_core/_io_windows.py:570:17: RUF050 Empty code branch
+ src/trio/_core/_io_windows.py:632:13: RUF050 Empty code branch
+ src/trio/_core/_run.py:601:13: RUF050 Empty code branch
+ src/trio/_core/_tests/test_ki.py:107:5: RUF050 Empty code branch
+ src/trio/_core/_tests/test_ki.py:99:5: RUF050 Empty code branch
+ src/trio/_dtls.py:793:17: RUF050 Empty code branch
+ src/trio/_subprocess_platform/__init__.py:82:5: RUF050 Empty code branch
+ src/trio/_tests/test_tracing.py:36:5: RUF050 Empty code branch
+ src/trio/testing/_fake_net.py:202:9: RUF050 Empty code branch

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

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
RUF050	286	286	0	0	0

Formatter (stable)

✅ ecosystem check detected no format changes.

Formatter (preview)

✅ ecosystem check detected no format changes.

[InSyncWithFoo]

Currently this rule is a bit too overzealous. It will also flag empty if/elif followed by non-empty elif/else.

Personally, I'm in favor of keeping this behaviour, as it enforces refactoring/denesting. I understand that I'm exceedingly likely to be in the minority, however.

[MichaReiser]

From a first skim through the ecosystem checks:

We should exclude branches with comments because it expresses that the branch is intentional:

• https://github.com/zulip/zulip/blob/7e92c2ad16c7f93a031227477c7d7e241482ac83/tools/lib/provision_inner.py#L291-L299
• https://github.com/indico/indico/blob/a111b446a3fda1a126df765df27562eec6e0a828/indico/cli/devserver.py#L231

I know this is quiet the opposite of what I said in the issue, but I just realised that clippy intentionally has multiple rules:

• empty-loop There are cases where an empty loop is intentional (e.g. a spin loop)
• empty-enum
• needless-else
• https://rust-lang.github.io/rust-clippy/master/index.html#needless_if

Thinking this through more, this makes sense to me because a needless-if is just useless where an empty loop can be correct sometimes.

Currently this rule is a bit too overzealous. It will also flag empty if/elif followed by non-empty elif/else.

I like using if or elif branches to skip early. It can help to avoid repeating the same condition in negated form for all following branches.

[InSyncWithFoo]

I like using if or elif branches to skip early. It can help to avoid repeating the same condition in negated form for all following branches.

In such cases, I would move the conditions to another function to take advantage of early returns, but that's just me.

---

As for splitting, I would like to use and reserve the RUF06* block, if that's alright with you. That way, it would be easier to select all of these closely related rules using a single selector.

[MichaReiser]

In such cases, I would move the conditions to another function to take advantage of early returns, but that's just me.

That's fair. I just think it's too opinionated for this rule. Such a branch isn't needless; it's more of a stylistic choice; you don't want any empty branches.

As for splitting, I would like to use and reserve the RUF06* block, if that's alright with you. That way, it would be easier to select all of these closely related rules using a single selector.

I don't think we want to block off an entire range for just a few rules.

Let's also hear from @AlexWaygood to ensure we're aligned to avoid changing our approach mroe than once

[gpauloski]

That's fair. I just think it's too opinionated for this rule. Such a branch isn't needless; it's more of a stylistic choice; you don't want any empty branches.

I agree. My intention when I opened the issue was just to detect what is most likely unintentional dead code (e.g., empty conditionals from other auto-fixes/formatters). I would not want deliberate style choices to get flagged, especially the empty branches with comments.

[MichaReiser]

Thanks for keeping this PR up to date. I talked to @AlexWaygood, and we agree that we should split this rule into multiple smaller rules. I'll comment on the issue with a suggestion. I'm sorry to have lead you in the wrong direction :(