remove incorrect fast path #146919

lcnr · 2025-09-23T06:30:14Z

Using tcx.is_copy_modulo_regions drops information from the current typing_env. Writing a regression test for this is really hard. We need to prove Copy of something that doesn't directly reference a coroutine or an opaque, but does so indirectly.

cc #146813.

rustbot · 2025-09-23T06:30:19Z

r? @fee1-dead

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lcnr · 2025-09-23T06:30:23Z

@bors try @rust-timer queue

yeet fast path

rust-bors · 2025-09-23T08:44:08Z

☀️ Try build successful (CI)
Build commit: 42c94cb (42c94cb36404561f642158badaaff2df4e506686, parent: f6092f224d2b1774b31033f12d0bee626943b02f)

rust-timer · 2025-09-23T12:13:54Z

Finished benchmarking commit (42c94cb): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

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

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: missing data
Artifact size: 389.94 MiB -> 387.92 MiB (-0.52%)

fee1-dead · 2025-09-23T14:49:19Z

r=me, but I've removed "Fixes" in the PR desc. That issue will need a test

rustbot · 2025-09-23T15:08:38Z

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

lcnr · 2025-09-23T15:38:52Z

removed one of the #[no_core] lang item tests. I don't think they're useful and we promise anything about the behavior

@bors r=fee1-dead rollup=never

bors · 2025-09-23T15:38:56Z

📌 Commit 83532f8 has been approved by fee1-dead

It is now in the queue for this repository.

lqd · 2025-09-24T11:55:56Z

This rollup=never PR has some time until it reaches the top of the queue, enough to add the MCVE from #146813 (comment)

lcnr · 2025-09-24T13:03:07Z

@bors r=fee1-dead rollup=never

bors · 2025-09-24T13:03:10Z

📌 Commit 7a0adc0 has been approved by fee1-dead

It is now in the queue for this repository.

wesleywiser · 2025-09-25T14:07:13Z

@bors p=1

Fix for P-high, stable-to-stable regression

bors · 2025-09-25T23:50:43Z

⌛ Testing commit 7a0adc0 with merge b733736...

bors · 2025-09-26T03:09:42Z

☀️ Test successful - checks-actions
Approved by: fee1-dead
Pushing b733736 to master...

github-actions · 2025-09-26T03:12:58Z

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 7ac0330 (parent) -> b733736 (this PR)

Test differences

Show 14 test diffs

Stage 1

[ui] tests/ui/coroutine/copy-fast-path-query-cycle.rs#current: [missing] -> pass (J1)
[ui] tests/ui/coroutine/copy-fast-path-query-cycle.rs#next: [missing] -> pass (J1)
[ui] tests/ui/lang-items/missing-copy-lang-item-issue-19660.rs: pass -> [missing] (J1)

Stage 2

[ui] tests/ui/coroutine/copy-fast-path-query-cycle.rs#current: [missing] -> pass (J0)
[ui] tests/ui/coroutine/copy-fast-path-query-cycle.rs#next: [missing] -> pass (J0)
[ui] tests/ui/lang-items/missing-copy-lang-item-issue-19660.rs: pass -> [missing] (J0)

Additionally, 8 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard b733736ea2feb7798c99cbb9a769bce74be108df --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

dist-aarch64-apple: 7712.4s -> 6149.5s (-20.3%)
x86_64-gnu-nopt: 6700.2s -> 7477.3s (11.6%)
x86_64-rust-for-linux: 2576.4s -> 2853.8s (10.8%)
x86_64-gnu-llvm-20: 2415.5s -> 2673.6s (10.7%)
i686-msvc-2: 7983.8s -> 7161.3s (-10.3%)
aarch64-apple: 6305.0s -> 5665.9s (-10.1%)
dist-i686-msvc: 7784.1s -> 8510.5s (9.3%)
aarch64-gnu-llvm-20-1: 3275.2s -> 3537.4s (8.0%)
x86_64-gnu-debug: 6553.3s -> 7072.0s (7.9%)
arm-android: 5615.8s -> 6036.7s (7.5%)

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 · 2025-09-26T04:21:16Z

Finished benchmarking commit (b733736): comparison URL.

Overall result: ❌ regressions - please read the text below

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.5%	[0.1%, 0.8%]	15
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.7%, secondary -2.6%)

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

	mean	range	count
Regressions ❌ (primary)	2.0%	[1.5%, 2.4%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-1.3%	[-1.5%, -1.1%]	2
Improvements ✅ (secondary)	-2.6%	[-2.8%, -2.4%]	2
All ❌✅ (primary)	0.7%	[-1.5%, 2.4%]	5

Cycles

Results (primary -0.7%, secondary 0.2%)

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

	mean	range	count
Regressions ❌ (primary)	2.8%	[2.8%, 2.8%]	1
Regressions ❌ (secondary)	2.6%	[2.6%, 2.6%]	1
Improvements ✅ (primary)	-2.5%	[-2.5%, -2.5%]	2
Improvements ✅ (secondary)	-2.3%	[-2.3%, -2.3%]	1
All ❌✅ (primary)	-0.7%	[-2.5%, 2.8%]	3

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 471.374s -> 472.685s (0.28%)
Artifact size: 388.15 MiB -> 388.17 MiB (0.00%)

apiraino · 2025-10-02T15:15:03Z

Backports accepted as per compiler team on Zulip. This stable backport alone does not necessarily justify a dot release. A backport PR will be authored by the release team at the end of the current development cycle. Backport labels handled by them.

@rustbot label +beta-accepted +stable-accepted

…inations, r=apiraino,Urgau Disable triagebot auto stable-regression compiler backport nominations pending redesign Current auto compiler stable-regression backport nominations seem to be too aggressive, and seems to unfortunately lower signal-to-noise ratio of the compiler backport channel. So this PR disables the triagebot compiler auto stable-regression backport nominations pending a redesign. Beta-regression auto backport nominations are not modified, we might want to gather some more experience with it. No prejudice against re-enabling them if the nominations include a bit more context on _why_ it's automatically nominated and _which_ regression(s) are being addressed. Or as proposed, it could also simply become a reminder-to-nominate _comment_. cf. [#t-compiler/backports > rust-lang#146919: stable-nominated @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/474880-t-compiler.2Fbackports/topic/.23146919.3A.20stable-nominated/near/540979327) > I like the idea of rustbot just posting a message that suggests adding the label. That seems like a good compromise between avoiding forgotten nominations and avoiding spurious nominations. In any case, this was very much worth experimenting! r? `@apiraino` (or triagebot)

Rollup merge of #147263 - jieyouxu:disable-auto-backport-nominations, r=apiraino,Urgau Disable triagebot auto stable-regression compiler backport nominations pending redesign Current auto compiler stable-regression backport nominations seem to be too aggressive, and seems to unfortunately lower signal-to-noise ratio of the compiler backport channel. So this PR disables the triagebot compiler auto stable-regression backport nominations pending a redesign. Beta-regression auto backport nominations are not modified, we might want to gather some more experience with it. No prejudice against re-enabling them if the nominations include a bit more context on _why_ it's automatically nominated and _which_ regression(s) are being addressed. Or as proposed, it could also simply become a reminder-to-nominate _comment_. cf. [#t-compiler/backports > #146919: stable-nominated @ 💬](https://rust-lang.zulipchat.com/#narrow/channel/474880-t-compiler.2Fbackports/topic/.23146919.3A.20stable-nominated/near/540979327) > I like the idea of rustbot just posting a message that suggests adding the label. That seems like a good compromise between avoiding forgotten nominations and avoiding spurious nominations. In any case, this was very much worth experimenting! r? `@apiraino` (or triagebot)

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 r? cuviper

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 - Make #[link="dl"] an FCW rather than an error #147262 r? cuviper

rustbot assigned fee1-dead Sep 23, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Sep 23, 2025

rustbot added the stable-nominated Nominated for backporting to the compiler in the stable channel. label Sep 23, 2025

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rust-bors bot added a commit that referenced this pull request Sep 23, 2025

Auto merge of #146919 - lcnr:yeet-fast-path, r=<try>

42c94cb

yeet fast path

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rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 23, 2025

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jieyouxu removed the stable-nominated Nominated for backporting to the compiler in the stable channel. label Sep 23, 2025

rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Sep 23, 2025

lcnr changed the title ~~yeet fast path~~ remove incorrect fast path Sep 23, 2025

rustbot added the stable-nominated Nominated for backporting to the compiler in the stable channel. label Sep 23, 2025

lcnr added 2 commits September 23, 2025 17:02

yeet fastpath

4fcafc9

remove test for no_core

83532f8

lcnr force-pushed the yeet-fast-path branch from 79ec372 to 83532f8 Compare September 23, 2025 15:08

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 23, 2025

cyrgani added the beta-nominated Nominated for backporting to the compiler in the beta channel. label Sep 24, 2025

add test

7a0adc0

bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 26, 2025

bors merged commit b733736 into rust-lang:master Sep 26, 2025
11 checks passed

rustbot added this to the 1.92.0 milestone Sep 26, 2025

rustbot added the perf-regression Performance regression. label Sep 26, 2025

Mark-Simulacrum added the perf-regression-triaged The performance regression has been triaged. label Sep 29, 2025

rustbot added beta-accepted Accepted for backporting to the compiler in the beta channel. stable-accepted Accepted for backporting to the compiler in the stable channel. labels Oct 2, 2025

cuviper mentioned this pull request Oct 2, 2025

[beta] backports #147284

Open

cuviper removed the beta-nominated Nominated for backporting to the compiler in the beta channel. label Oct 2, 2025

cuviper modified the milestones: 1.92.0, 1.91.0 Oct 2, 2025

bors added a commit that referenced this pull request Oct 3, 2025

Auto merge of #147284 - cuviper:beta-next, r=cuviper

93b26c2

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 r? cuviper

bors added a commit that referenced this pull request Oct 3, 2025

Auto merge of #147284 - cuviper:beta-next, r=cuviper

12b7c51

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 r? cuviper

bors added a commit that referenced this pull request Oct 4, 2025

Auto merge of #147284 - cuviper:beta-next, r=cuviper

4195364

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 r? cuviper

bors added a commit that referenced this pull request Oct 5, 2025

Auto merge of #147284 - cuviper:beta-next, r=cuviper

e76bb13

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 r? cuviper

bors added a commit that referenced this pull request Oct 5, 2025

Auto merge of #147284 - cuviper:beta-next, r=cuviper

c04b0d1

[beta] backports - remove incorrect fast path #146919 - Update LLVM to 21.1.2 #146953 - Fix infinite recursion in Path::eq with String #146958 r? cuviper

remove incorrect fast path #146919

remove incorrect fast path #146919

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rust-timer commented Sep 23, 2025

Overall result: no relevant changes - no action needed

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lcnr commented Sep 23, 2025

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github-actions bot commented Sep 26, 2025

Test differences

Stage 1

Stage 2

Job duration changes

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rust-timer commented Sep 26, 2025

Overall result: ❌ regressions - please read the text below

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apiraino commented Oct 2, 2025

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lcnr commented Sep 23, 2025 •

edited by fee1-dead

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