[perflint] Extend PERF102 to comprehensions and generators

[anishgirianish]

Summary

Extends PERF102 to catch .items() misuse in comprehensions and generators, not just for loops.

Extracted the core detection into a shared helper (check_dict_items_usage) so both the for loop and comprehension paths can reuse it. The comprehension check runs between Step 2 and Step 3 in visit_expr since is_unused() needs the generator scope to still be active.

now flagged
_ = [k for k, _ in d.items()] # use .keys()
_ = {v for _, v in d.items()} # use .values()
_ = (v for _, v in d.items()) # use .values()

still fine
_ = [(k, v) for k, v in d.items()] # both used
_ = [k for k, v in d.items() if v] # v used in condition

Test Plan

• Added error and no-error cases for list/set/dict comps, generators, and nested generators
• Tests, clippy, and prek all pass

Closes #6638

[astral-sh-bot]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

ℹ️ ecosystem check detected linter changes. (+39 -0 violations, +0 -0 fixes in 11 projects; 45 projects unchanged)

apache/airflow (+7 -0 violations, +0 -0 fixes)

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

+ airflow-core/src/airflow/models/deadline.py:289:40: PERF102 When using only the values of a dict use the `values()` method
+ airflow-core/src/airflow/serialization/definitions/deadline.py:75:40: PERF102 When using only the values of a dict use the `values()` method
+ airflow-core/src/airflow/serialization/serialized_objects.py:1699:75: PERF102 When using only the values of a dict use the `values()` method
+ airflow-core/src/airflow/utils/sqlalchemy.py:189:28: PERF102 When using only the keys of a dict use the `keys()` method
+ providers/databricks/src/airflow/providers/databricks/operators/databricks_workflow.py:179:34: PERF102 When using only the values of a dict use the `values()` method
+ providers/teradata/src/airflow/providers/teradata/hooks/teradata.py:302:57: PERF102 When using only the values of a dict use the `values()` method
+ task-sdk/src/airflow/sdk/definitions/_internal/expandinput.py:267:44: PERF102 When using only the values of a dict use the `values()` method

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:546:50: PERF102 When using only the keys of a dict use the `keys()` method

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

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

+ ibis/expr/sql.py:263:59: PERF102 When using only the values of a dict use the `values()` method

langchain-ai/langchain (+1 -0 violations, +0 -0 fixes)

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

+ libs/core/tests/unit_tests/prompts/test_structured.py:24:57: PERF102 When using only the keys of a dict use the `keys()` method

latchbio/latch (+1 -0 violations, +0 -0 fixes)

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

+ src/latch_cli/snakemake/workflow.py:1568:32: PERF102 When using only the keys of a dict use the `keys()` method

qdrant/qdrant-client (+3 -0 violations, +0 -0 fixes)

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

+ qdrant_client/local/async_qdrant_local.py:661:34: PERF102 When using only the keys of a dict use the `keys()` method
+ qdrant_client/local/local_collection.py:122:43: PERF102 When using only the keys of a dict use the `keys()` method
+ qdrant_client/local/qdrant_local.py:718:32: PERF102 When using only the keys of a dict use the `keys()` method

rotki/rotki (+4 -0 violations, +0 -0 fixes)

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

+ rotkehlchen/api/services/external_services.py:16:84: PERF102 When using only the values of a dict use the `values()` method
+ rotkehlchen/chain/evm/decoding/hop/decoder.py:80:29: PERF102 When using only the values of a dict use the `values()` method
+ rotkehlchen/rotkehlchen.py:1222:58: PERF102 When using only the values of a dict use the `values()` method
+ rotkehlchen/rotkehlchen.py:1223:76: PERF102 When using only the values of a dict use the `values()` method

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

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

+ zerver/lib/events.py:2283:46: PERF102 When using only the values of a dict use the `values()` method

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

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

+ indico/core/permissions.py:122:35: PERF102 [*] When using only the values of a dict use the `values()` method
+ indico/core/permissions.py:236:55: PERF102 [*] When using only the values of a dict use the `values()` method
+ indico/modules/events/layout/util.py:190:34: PERF102 [*] When using only the values of a dict use the `values()` method
+ indico/modules/events/layout/util.py:269:31: PERF102 [*] When using only the values of a dict use the `values()` method
+ indico/modules/vc/models/vc_rooms.py:43:73: PERF102 [*] When using only the values of a dict use the `values()` method

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

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

+ src/pdm/installers/base.py:209:28: PERF102 When using only the keys of a dict use the `keys()` method

home-assistant/core (+14 -0 violations, +0 -0 fixes)

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

+ homeassistant/components/apcupsd/sensor.py:474:60: PERF102 When using only the keys of a dict use the `keys()` method
+ homeassistant/components/blink/diagnostics.py:25:26: PERF102 When using only the values of a dict use the `values()` method
+ homeassistant/components/canary/alarm_control_panel.py:31:38: PERF102 When using only the values of a dict use the `values()` method
+ homeassistant/components/fritz/diagnostics.py:48:34: PERF102 When using only the values of a dict use the `values()` method
+ homeassistant/components/hvv_departures/binary_sensor.py:123:27: PERF102 When using only the keys of a dict use the `keys()` method
+ homeassistant/components/insteon/api/aldb.py:66:67: PERF102 When using only the values of a dict use the `values()` method
+ homeassistant/components/rympro/sensor.py:71:32: PERF102 When using only the keys of a dict use the `keys()` method
+ homeassistant/components/schluter/climate.py:74:42: PERF102 When using only the keys of a dict use the `keys()` method
+ homeassistant/components/seventeentrack/sensor.py:28:37: PERF102 When using only the keys of a dict use the `keys()` method
+ homeassistant/components/vodafone_station/diagnostics.py:42:39: PERF102 When using only the values of a dict use the `values()` method
+ homeassistant/components/weatherflow_cloud/weather.py:38:37: PERF102 When using only the keys of a dict use the `keys()` method
+ script/hassfest/config_flow.py:150:36: PERF102 When using only the keys of a dict use the `keys()` method
+ tests/components/keenetic_ndms2/test_config_flow.py:241:21: PERF102 When using only the keys of a dict use the `keys()` method
+ tests/components/kostal_plenticore/test_switch.py:107:24: PERF102 When using only the keys of a dict use the `keys()` method

Changes by rule (1 rules affected)

code	total	+ violation	- violation	+ fix	- fix
PERF102	39	39	0	0	0

[ntBre]

Thanks! This looks reasonable to me overall, I mostly just had a couple of nits and then a larger suggestion about where to put this check.

We should also make this a preview change since it's a significant expansion to a stable rule.

[amyreese]

I really like the ecosystem hits here, didn't realize how common it was to use items() without using both key and value. 😅

That said, when giving advice to use keys(), would it be better to simply recommend iterating over the dictionary itself (which defaults to iterating over keys)? Or does PERF102 already suggest keys() for a specific reason?

[ntBre]

That said, when giving advice to use keys(), would it be better to simply recommend iterating over the dictionary itself (which defaults to iterating over keys)? Or does PERF102 already suggest keys() for a specific reason?

Let's not change too much about PERF102 in this PR 😄 I don't know the full history of recommending keys, but I'm happy to reuse the rule's normal fix for loops here.

[ntBre]

Based on the ecosystem check, we still need to preview gate this change.

[anishgirianish]

@ntBre Addressed all feedback with latest commits:

• Preview gated comprehension checks.
• Removed &'a Comprehension from Analyze.

Would like to request you for your review whenever you get a chance. Thank you

[ntBre]

Thank you! This makes sense to me.

I'll just apply my one suggestion adding a debug assertion to make it slightly more like the other deferred checks.

[anishgirianish]

Thank you! This makes sense to me.

I'll just apply my one suggestion adding a debug assertion to make it slightly more like the other deferred checks.

Thank you very much for the latest push. I really appreciate it.