Migration of `LintDiagnostic` - part 5 by GuillaumeGomez · Pull Request #153152 · rust-lang/rust

GuillaumeGomez · 2026-02-26T20:40:42Z

With this, rust_lint is finally done, although the change of API of decorate_builtin_lint impacted a few other crates, although minimal, still needed to be mentioned.

r? @JonathanBrouwer

rustbot · 2026-02-26T20:40:47Z

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

JonathanBrouwer · 2026-02-26T21:38:36Z

@bors try @rust-timer queue

Migration of LintDiagnostic - part 5

compiler/rustc_lint/src/early/diagnostics.rs

src/librustdoc/lib.rs

compiler/rustc_lint/src/context.rs

compiler/rustc_lint/src/early/diagnostics.rs

GuillaumeGomez · 2026-02-26T23:18:42Z

Simplified EmitDiag and removed duplicated code. Keeping the last item for after this PR is merged as it's already big enough.

rust-bors · 2026-02-26T23:50:31Z

☀️ Try build successful (CI)
Build commit: 0c55ed2 (0c55ed2450ed4df93bd1cbfbca3f3e31a391a171, parent: 25396cf54981afd1fa5a7406658b45033106a0d3)

rust-timer · 2026-02-27T03:22:37Z

Finished benchmarking commit (0c55ed2): comparison URL.

Overall result: ❌ regressions - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@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)	2.3%	[0.5%, 3.8%]	13
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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

Cycles

Results (primary -6.1%, secondary 2.3%)

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)	4.0%	[3.7%, 4.7%]	3
Improvements ✅ (primary)	-6.1%	[-6.1%, -6.1%]	1
Improvements ✅ (secondary)	-3.0%	[-3.0%, -3.0%]	1
All ❌✅ (primary)	-6.1%	[-6.1%, -6.1%]	1

Binary size

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

Bootstrap: 481.72s -> 480.975s (-0.15%)
Artifact size: 395.60 MiB -> 395.80 MiB (0.05%)

JonathanBrouwer · 2026-02-27T09:24:36Z

If not too annoying I'd like to see the perf regression fixed as well

JonathanBrouwer · 2026-03-02T19:21:20Z

@bors r+ rollup=never
I've spent a few hours locally debugging this perf regression, it seems to be caused by decorate_builtin_lint being called if the lint level is Allow, whereas previously it would quick-exit before this already. I think this is hard to prevent, and the regression is small enough (2% on a secondary test that literally does nothing other than emit allowed lints) that it's fine to accept it.

I've added taking a further look at this to the TODO list of the tracking issue, I have some ideas but don't have time right away to try those out

rust-bors · 2026-03-02T19:21:24Z

📌 Commit 3bc1950 has been approved by JonathanBrouwer

It is now in the queue for this repository.

fmease · 2026-03-02T19:37:47Z

IIUC this PR basically undoes my PR #125410 (its perf vs this PR's perf). It's very intentional that these were decorated lazily.

Why can't the decorating keep happening lazily for decorate_builtin_lint under the new API you're working towards?

JonathanBrouwer · 2026-03-02T19:58:09Z

That PR's perf had effect on primary benchmarks, while this one only regresses the secondary benchmark, so it's definitely not fully undoing your work.

It's not easy because the new API we're working towards making lint_level take a impl Diagnostic for consistency with errors & warnings, which is harder to properly make lazy. I still think it's possible, one of my ideas is a custom implementation of Diagnostic for BuiltinDiag, but I'd prefer to do that in a separate PR since this one is already on the larger size.

I like perf just as much as you, and I do want to fix this, just don't think the perf regression is bad enough that it has to be done now

… and `rustdoc`

rustbot · 2026-03-02T22:48:04Z

This PR was rebased onto a different main 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.

JonathanBrouwer · 2026-03-02T22:48:51Z

^ Rebased to solve merge conflicts

JonathanBrouwer · 2026-03-02T22:49:01Z

@bors try cancel
@bors try

rust-bors · 2026-03-02T22:49:04Z

Try build cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/22598721349

Migration of LintDiagnostic - part 5

GuillaumeGomez

Github doesn't allow to approve your own PR but your changes look good to me, thanks!

View changes since this review

rust-bors · 2026-03-03T00:58:41Z

☀️ Try build successful (CI)
Build commit: e2bd8b9 (e2bd8b9142745e8d99284919273adec4edb2d3a9, parent: 8ddf4ef064fb702fed0f3d239ec8d0bac607484e)

rust-timer · 2026-03-03T01:39:09Z

Finished benchmarking commit (e2bd8b9): comparison URL.

Overall result: ❌✅ regressions and improvements - 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

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)	0.0%	[0.0%, 0.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 1.9%, 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)	2.5%	[1.7%, 3.4%]	4
Regressions ❌ (secondary)	3.2%	[3.2%, 3.2%]	1
Improvements ✅ (primary)	-0.7%	[-0.7%, -0.7%]	1
Improvements ✅ (secondary)	-1.8%	[-2.3%, -1.2%]	2
All ❌✅ (primary)	1.9%	[-0.7%, 3.4%]	5

Cycles

Results (secondary 4.9%)

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)	4.9%	[3.4%, 6.4%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 480.113s -> 479.022s (-0.23%)
Artifact size: 396.96 MiB -> 394.98 MiB (-0.50%)

JonathanBrouwer · 2026-03-03T06:07:26Z

@bors r+ rollup

rust-bors · 2026-03-03T06:07:28Z

📌 Commit 8a824ee has been approved by JonathanBrouwer

It is now in the queue for this repository.

…uwer Rollup of 12 pull requests Successful merges: - #152941 (prefer actual ABI-controling fields over target.abi when making ABI decisions) - #153227 (Don’t report missing fields in struct exprs with syntax errors.) - #153265 (Clarified doc comments + added tests confirming current behavior for intersperse/intersperse_with) - #152966 (Migrate 11 tests from tests/ui/issues to specific directories) - #153003 (rustdoc: make `--emit` and `--out-dir` mimic rustc) - #153034 (Remove unhelpful hint from trivial bound errors) - #153152 (Migration of LintDiagnostic - part 5) - #153177 (disable the ptr_fragment_in_final test on s390x) - #153221 (Add release notes for 1.94.0) - #153279 (feat: Provide an '.item_kind()' method on ItemEnum) - #153297 (Update the name of the Hermit operating system) - #153309 (Cleanup of c-variadic link test)

@JonathanBrouwer

Rollup merge of #153152 - GuillaumeGomez:migrate-diag, r=JonathanBrouwer Migration of LintDiagnostic - part 5 Part of #153099. With this, `rust_lint` is finally done, although the change of API of `decorate_builtin_lint` impacted a few other crates, although minimal, still needed to be mentioned. r? @JonathanBrouwer

fmease · 2026-03-03T10:55:21Z

Thanks a bunch for addressing the perf regression, @JonathanBrouwer 🙏❤️

rustbot assigned JonathanBrouwer Feb 26, 2026

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. T-rustdoc Relevant to the rustdoc team, which will review and decide on the PR/issue. labels Feb 26, 2026

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rust-bors bot pushed a commit that referenced this pull request Feb 26, 2026

Auto merge of #153152 - GuillaumeGomez:migrate-diag, r=<try>

0c55ed2

Migration of LintDiagnostic - part 5

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Feb 26, 2026

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rustbot added perf-regression Performance regression. and removed S-waiting-on-perf Status: Waiting on a perf run to be completed. labels Feb 27, 2026

GuillaumeGomez force-pushed the migrate-diag branch from d39a00a to f3d639f Compare February 27, 2026 17:23

GuillaumeGomez mentioned this pull request Feb 27, 2026

Perf check for Diag migration #153193

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rust-bors bot 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 2, 2026

GuillaumeGomez and others added 4 commits March 2, 2026 23:46

Simplify rustc_lint::EmitDiag by removing Lint from its API

71e2ecd

Remove duplicated code for delayed lints between rustc_hir_analysis…

62cb683

… and `rustdoc`

Make DiagEmitter::emit take self by value

2be5835

Fix performance of early lints

8a824ee

JonathanBrouwer force-pushed the migrate-diag branch from 7597288 to 8a824ee Compare March 2, 2026 22:48

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Auto merge of #153152 - GuillaumeGomez:migrate-diag, r=<try>

e2bd8b9

Migration of LintDiagnostic - part 5

GuillaumeGomez commented Mar 3, 2026

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rustbot removed S-waiting-on-perf Status: Waiting on a perf run to be completed. perf-regression Performance regression. labels Mar 3, 2026

rust-bors bot 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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 3, 2026

JonathanBrouwer mentioned this pull request Mar 3, 2026

Rollup of 12 pull requests #153331

Merged

rust-bors bot merged commit 4a56a45 into rust-lang:main Mar 3, 2026
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rustbot added this to the 1.96.0 milestone Mar 3, 2026

GuillaumeGomez deleted the migrate-diag branch March 3, 2026 13:34

GuillaumeGomez mentioned this pull request Mar 3, 2026

Tracking Issue for LintDiagnostic migration #153099

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GuillaumeGomez changed the title ~~Migration of LintDiagnostic - part 5~~ Migration of LintDiagnostic - part 5 Mar 3, 2026

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rust-timer commented Feb 27, 2026

Overall result: ❌ regressions - please read the text below

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Overall result: ❌✅ regressions and improvements - no action needed

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