Propagate `#[allow(dead_code)]` on adts to their inherent impls by mu001999 · Pull Request #157885 · rust-lang/rust

mu001999 · 2026-06-14T10:44:36Z

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This PR does:

propagate #[allow(dead_code)] on adts to their inherent impls and impl items
refactor the previous implementation for impl items of traits, and improve the performance

After the above, there is still some slight perf regressions because we indeed do more things (for inherent impls).

Fixes #149142

mu001999 · 2026-06-15T00:41:31Z

@bors try @rust-timer queue

Propagate `#[allow(dead_code)]` on adts to their inherent impls

rust-bors · 2026-06-15T02:53:19Z

☀️ Try build successful (CI)
Build commit: 25aedf1 (25aedf1c569cd8fb010ed559082eacf12d56aaa2, parent: 3daae5e42ec9ba435212987331af1b7b8634fa90)

rust-timer · 2026-06-15T03:34:20Z

Finished benchmarking commit (25aedf1): comparison URL.

Overall result: ❌ regressions - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.5%	[0.1%, 0.9%]	52
Regressions ❌ (secondary)	0.4%	[0.2%, 0.7%]	16
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[-0.2%, 0.9%]	53

Max RSS (memory usage)

Results (primary -2.3%, secondary -1.0%)

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

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.9%	[-6.9%, -0.9%]	3
Improvements ✅ (secondary)	-1.0%	[-1.0%, -1.0%]	1
All ❌✅ (primary)	-2.3%	[-6.9%, 2.3%]	4

Cycles

Results (secondary 21.3%)

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)	21.3%	[20.3%, 22.4%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 519.503s -> 518.599s (-0.17%)
Artifact size: 401.51 MiB -> 401.51 MiB (-0.00%)

mu001999 · 2026-06-16T16:18:49Z

@bors try @rust-timer queue

Propagate `#[allow(dead_code)]` on adts to their inherent impls

rust-bors · 2026-06-16T18:30:21Z

☀️ Try build successful (CI)
Build commit: 848b0fa (848b0fabbf422f36bd3435a5abda617bf5da7395, parent: 89a99936d9e76a50e8df622e7242190841fd871b)

rust-timer · 2026-06-16T19:11:13Z

Finished benchmarking commit (848b0fa): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.2%	[0.2%, 0.2%]	3
Regressions ❌ (secondary)	0.3%	[0.2%, 0.4%]	12
Improvements ✅ (primary)	-0.3%	[-0.7%, -0.2%]	14
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	2
All ❌✅ (primary)	-0.2%	[-0.7%, 0.2%]	17

Max RSS (memory usage)

Results (primary -5.4%, secondary 1.7%)

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)	3.3%	[1.6%, 5.8%]	3
Improvements ✅ (primary)	-5.4%	[-5.4%, -5.4%]	1
Improvements ✅ (secondary)	-3.2%	[-3.2%, -3.2%]	1
All ❌✅ (primary)	-5.4%	[-5.4%, -5.4%]	1

Cycles

Results (secondary 1.4%)

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)	4.4%	[4.4%, 4.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.7%	[-1.7%, -1.7%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 522.035s -> 522.314s (0.05%)
Artifact size: 401.81 MiB -> 401.26 MiB (-0.14%)

mu001999 · 2026-06-17T01:16:45Z

@bors try @rust-timer queue

rust-bors · 2026-06-17T03:33:24Z

☀️ Try build successful (CI)
Build commit: ed5706a (ed5706a69a8b278c09e17ef108bbf5a831a23316, parent: 9e2abe0c6ab27fcbb95c30695188a75776e2feb1)

rust-timer · 2026-06-17T04:44:43Z

Finished benchmarking commit (ed5706a): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.3%	[0.2%, 0.3%]	7
Regressions ❌ (secondary)	0.3%	[0.1%, 0.4%]	14
Improvements ✅ (primary)	-0.6%	[-1.4%, -0.2%]	23
Improvements ✅ (secondary)	-0.2%	[-0.2%, -0.2%]	1
All ❌✅ (primary)	-0.4%	[-1.4%, 0.3%]	30

Max RSS (memory usage)

Results (primary 0.9%, secondary 4.7%)

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

	mean	range	count
Regressions ❌ (primary)	1.8%	[1.2%, 2.3%]	2
Regressions ❌ (secondary)	4.7%	[2.1%, 7.3%]	2
Improvements ✅ (primary)	-0.9%	[-0.9%, -0.9%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[-0.9%, 2.3%]	3

Cycles

Results (secondary 3.8%)

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)	3.8%	[3.8%, 3.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 522.871s -> 521.923s (-0.18%)
Artifact size: 401.31 MiB -> 401.34 MiB (0.01%)

mu001999 · 2026-06-17T07:59:20Z

@bors try @rust-timer queue

Propagate `#[allow(dead_code)]` on adts to their inherent impls

rust-bors · 2026-06-17T10:15:14Z

☀️ Try build successful (CI)
Build commit: 4d34c0f (4d34c0f5d692d92842d17a23bb004c9a68935c62)
Base parent: 98594f4 (98594f404ee741f97fefbae4aca049cde911bc94)

rust-timer · 2026-06-17T11:31:55Z

Finished benchmarking commit (4d34c0f): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.3%	[0.2%, 0.3%]	7
Regressions ❌ (secondary)	0.4%	[0.4%, 0.4%]	6
Improvements ✅ (primary)	-0.6%	[-1.4%, -0.2%]	25
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	-0.4%	[-1.4%, 0.3%]	32

Max RSS (memory usage)

Results (primary 3.9%, secondary 3.8%)

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

	mean	range	count
Regressions ❌ (primary)	3.9%	[3.9%, 3.9%]	1
Regressions ❌ (secondary)	3.8%	[3.8%, 3.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	3.9%	[3.9%, 3.9%]	1

Cycles

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

Binary size

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

Bootstrap: 523.739s -> 522.828s (-0.17%)
Artifact size: 401.37 MiB -> 401.86 MiB (0.12%)

mu001999 · 2026-06-18T07:12:39Z

@bors try @rust-timer queue

Propagate `#[allow(dead_code)]` on adts to their inherent impls

rust-bors · 2026-06-18T09:24:04Z

☀️ Try build successful (CI)
Build commit: ac3f172 (ac3f1720b43fdf1c580ee653c1a9db9b9e07b739)
Base parent: 3768ec0 (3768ec06c826ef667b65a7d084610a11baf10776)

rust-timer · 2026-06-18T10:28:14Z

Finished benchmarking commit (ac3f172): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.2%	[0.2%, 0.3%]	3
Regressions ❌ (secondary)	0.4%	[0.4%, 0.4%]	6
Improvements ✅ (primary)	-0.6%	[-1.4%, -0.2%]	29
Improvements ✅ (secondary)	-0.4%	[-0.4%, -0.3%]	2
All ❌✅ (primary)	-0.5%	[-1.4%, 0.3%]	32

Max RSS (memory usage)

Results (primary -1.0%)

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

	mean	range	count
Regressions ❌ (primary)	1.3%	[1.3%, 1.3%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.2%	[-2.8%, -1.5%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.0%	[-2.8%, 1.3%]	3

Cycles

Results (primary 2.9%, secondary -0.1%)

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

	mean	range	count
Regressions ❌ (primary)	2.9%	[2.2%, 4.0%]	5
Regressions ❌ (secondary)	2.8%	[2.8%, 2.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.1%	[-3.1%, -3.1%]	1
All ❌✅ (primary)	2.9%	[2.2%, 4.0%]	5

Binary size

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

Bootstrap: 522.822s -> 523.673s (0.16%)
Artifact size: 401.33 MiB -> 401.44 MiB (0.03%)

rustbot · 2026-06-18T14:44:05Z

r? @dingxiangfei2009

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 14, 2026

qaijuang reviewed Jun 14, 2026

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Comment thread compiler/rustc_passes/src/dead.rs Outdated

qaijuang reviewed Jun 14, 2026

View reviewed changes

Comment thread compiler/rustc_passes/src/dead.rs Outdated

mu001999 force-pushed the dead-code/improve branch from 0ff50d6 to 93cdd71 Compare June 14, 2026 14:43