Lang item cleanups

[oli-obk]

a grab bag of cleanups around lang item collection and various documentation things I found while poking around that area

r? @JonathanBrouwer

[rustbot]

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

[rustbot]

JonathanBrouwer is currently at their maximum review capacity.
They may take a while to respond.

[oli-obk]

@bors try @rust-timer queue

[bjorn3]

Another minor cleanup: WEAK_ONLY_LANG_ITEMS doesn't look to be used anywhere. Only LangItem::is_weak_only is used.

[rust-bors]

☀️ Try build successful (CI)
Build commit: 80e7599 (80e75997d7b5e008b36315517f09f1b92496d928)
Base parent: 07074cf (07074cfe1d991fe06b7fc613bbbd1dd9d0d37c80)

[rust-timer]

Finished benchmarking commit (80e7599): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.2%]	39
Improvements ✅ (secondary)	-0.3%	[-0.5%, -0.1%]	42
All ❌✅ (primary)	-0.3%	[-0.5%, -0.2%]	39

Max RSS (memory usage)

This perf run didn't have relevant results for this metric.

Cycles

Results (secondary 0.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.4%	[1.9%, 2.8%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	-	-	0

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 489.352s -> 489.442s (0.02%)
Artifact size: 388.43 MiB -> 388.34 MiB (-0.02%)

[JonathanBrouwer]

@bors r+

View changes since this review

[rust-bors]

📌 Commit 9dcde56 has been approved by JonathanBrouwer

It is now in the queue for this repository.

[rust-bors]

☀️ Test successful - CI
Approved by: JonathanBrouwer
Duration: 3h 6m 55s
Pushing 48e8ec6 to main...

[github-actions]

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 375b143 (parent) -> 48e8ec6 (this PR)

Test differences

Show 6 test diffs

6 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 48e8ec6f05057f942a97187dde770a118e05f42c --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

1. dist-android: 28m 48s -> 18m 38s (-35.3%)
2. i686-gnu-nopt-2: 1h 43m -> 2h 20m (+35.3%)
3. dist-i686-linux: 1h 23m -> 1h 51m (+32.9%)
4. test-various: 1h 40m -> 2h 12m (+32.1%)
5. x86_64-gnu-llvm-21: 1h 20m -> 59m 32s (-26.0%)
6. dist-ohos-x86_64: 1h 2m -> 1h 16m (+22.0%)
7. x86_64-gnu-llvm-22-1: 1h 14m -> 58m 31s (-21.6%)
8. x86_64-gnu-gcc: 1h 7m -> 54m 6s (-20.1%)
9. x86_64-gnu-llvm-22-3: 1h 23m -> 1h 39m (+19.1%)
10. dist-arm-linux-musl: 1h 32m -> 1h 16m (-17.1%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

[rust-timer]

Finished benchmarking commit (48e8ec6): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.3%	[-0.5%, -0.1%]	48
Improvements ✅ (secondary)	-0.3%	[-0.6%, -0.2%]	38
All ❌✅ (primary)	-0.3%	[-0.5%, -0.1%]	48

Max RSS (memory usage)

Results (primary -2.8%, secondary 4.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	4.1%	[4.1%, 4.1%]	1
Improvements ✅ (primary)	-2.8%	[-2.8%, -2.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.8%	[-2.8%, -2.8%]	1

Cycles

Results (primary -0.5%, secondary -1.2%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.2%	[2.2%, 2.2%]	1
Regressions ❌ (secondary)	2.4%	[2.4%, 2.4%]	1
Improvements ✅ (primary)	-1.8%	[-2.2%, -1.5%]	2
Improvements ✅ (secondary)	-3.0%	[-3.7%, -2.4%]	2
All ❌✅ (primary)	-0.5%	[-2.2%, 2.2%]	3

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 490.777s -> 490.729s (-0.01%)
Artifact size: 389.74 MiB -> 389.29 MiB (-0.11%)