Rollup of 5 pull requests by JonathanBrouwer · Pull Request #155611 · rust-lang/rust

JonathanBrouwer · 2026-04-21T18:42:54Z

Successful merges:

Improve E0308 error message for impl Trait return mismatches #155546 (Improve E0308 error message for impl Trait return mismatches)
Fix incorrect let to const suggestion for pattern bindings #152834 (Fix incorrect let to const suggestion for pattern bindings)
Remove duplicated Flags methods. #155425 (Remove duplicated Flags methods.)
Use per-parent disambiguators everywhere #155547 (Use per-parent disambiguators everywhere)
Remove AttributeLintKind variants - part 5 #155590 (Remove AttributeLintKind variants - part 5)

The `Flags` trait has two methods: `flags` and `outer_exclusive_binder`. Multiple types impl this trait and then also have duplicate inherent methods with the same names; these are all marked with "Think about removing this" comments. This is left over from things being moved into `rustc_type_ir`. This commit removes those inherent methods. This requires adding `use Flags` to a number of files.

When a function returns `impl Trait`, all branches must return the same concrete type. Previously, the compiler showed: expected `First` because of return type This was misleading, as it suggested the return type was `First`, rather than any single type implementing the trait. Update the diagnostic to: expected a single type implementing `Value` because of return type Also highlight the first return expression to make it clearer why subsequent returns do not match. Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>

…and not the old one

…ebank Improve E0308 error message for `impl Trait` return mismatches When a function returns `impl Trait`, all branches must return the same concrete type. Previously, the compiler showed: expected `First` because of return type This was misleading, as it suggested the return type was `First`, rather than any single type implementing the trait. Update the diagnostic to: expected a single type implementing `Value` because of return type Also highlight the first return expression to make it clearer why subsequent returns do not match.

Fix incorrect `let` to `const` suggestion for pattern bindings When a variable from a pattern binding was referenced inside a `const {}` block, the compiler incorrectly suggested replacing `let` with `const`. This was reported in rust-lang#152831 for `if let`, but also applies to `while let` and `let ... else`.

@lcnr

…r=nikomatsakis Remove duplicated `Flags` methods. The `Flags` trait has two methods: `flags` and `outer_exclusive_binder`. Multiple types impl this trait and then also have duplicate inherent methods with the same names; these are all marked with "Think about removing this" comments. This is left over from things being moved into `rustc_type_ir`. This commit removes those inherent methods. This requires adding `use Flags` to a number of files. r? @lcnr

@petrochenkov

…=oli-obk Use per-parent disambiguators everywhere This PR addressing the following concerns about per-parent disambiguators (rust-lang#153955): - DisambiguatorState is removed, PerParentDisambiguatorState is now used everywhere, - Steals were removed from every per-parent disambiguator in resolver, - It adds `parent` field in `PerParentDisambiguatorState` in `#[cfg(debug_assertions)]` for asserting that per-parent disambiguator corresponds to the same `LocalDefId` which is passed into `create_def`, - ~Removes `Disambiguator` trait replacing it with `Disambiguator` enum, with this change we no longer expose `next` method (as trait should be public otherwise the warning will be emitted). It may affect perf in a negative way though.~ ~Those changes should not fix perf issues that were [reported](rust-lang#153955 (comment)), perf run that was attempted [before](rust-lang#153955 (comment)) showed much better results. Performance can be probably fixed by removing per-parent disambiguators replacing them with a single one as it was before, then it will be passed to AST -> HIR lowering and modified. For delayed owners we can store ~followup disambiguators as it was in the beginning of the rust-lang#153955~ per-parent disambiguators. This solution should save achievements from rust-lang#153955 (removed `DefPathData` variants). However, I would prefer to keep per-parent disambiguators as it seems a better architectural solution for me.~ r? @petrochenkov cc @oli-obk

@JonathanBrouwer

…d, r=JonathanBrouwer Remove AttributeLintKind variants - part 5 Part of rust-lang#153099. r? @JonathanBrouwer

JonathanBrouwer · 2026-04-21T18:43:00Z

@bors r+ rollup=never p=5

rust-bors · 2026-04-21T18:43:03Z

📌 Commit 79e2ff7 has been approved by JonathanBrouwer

It is now in the queue for this repository.

rust-bors · 2026-04-22T02:57:12Z

☀️ Test successful - CI
Approved by: JonathanBrouwer
Duration: 3h 22m 15s
Pushing f9988fe to main...

rust-timer · 2026-04-22T02:58:42Z

📌 Perf builds for each rolled up PR:

PR#	Message	Perf Build Sha
#152834	Fix incorrect `let` to `const` suggestion for pattern bindi…	`1fb0491c4fc5bd7691750b58fcf4a3ad87624339` (link)
#155425	Remove duplicated `Flags` methods.	`3c5e7aaddbef8c84ec10d4b0ccc62b740dcc6ad9` (link)
#155546	Improve E0308 error message for `impl Trait` return mismatc…	`d5e6622e4a64fc0abc61eed355a9c6e35de38b02` (link)
#155547	Use per-parent disambiguators everywhere	`64e60df1d6538c86802b895acccf8afa852ba29b` (link)
#155590	Remove AttributeLintKind variants - part 5	`d9317ef68569b1e43b1ebb365037bd1c72032367` (link)

previous master: 9ec5d5f32e

In the case of a perf regression, run the following command for each PR you suspect might be the cause: @rust-timer build $SHA

github-actions · 2026-04-22T03:00:24Z

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 9ec5d5f (parent) -> f9988fe (this PR)

Test differences

Show 60 test diffs

Stage 1

[ui] tests/ui/consts/non-const-value-in-const-irrefutable-pat-binding.rs: [missing] -> pass (J1)
[ui] tests/ui/consts/non-const-value-in-const-pat-binding.rs: [missing] -> pass (J1)

Stage 2

[ui] tests/ui/consts/non-const-value-in-const-irrefutable-pat-binding.rs: [missing] -> pass (J0)
[ui] tests/ui/consts/non-const-value-in-const-pat-binding.rs: [missing] -> pass (J0)

Additionally, 56 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 f9988fefd3add01f414f52b414308e7872622fee --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

x86_64-gnu-llvm-22-1: 53m 22s -> 1h 16m (+42.5%)
i686-msvc-1: 2h 18m -> 3h 10m (+37.8%)
dist-ohos-x86_64: 1h 2m -> 1h 20m (+29.9%)
dist-powerpc64le-linux-gnu: 1h 17m -> 1h 36m (+25.1%)
x86_64-rust-for-linux: 43m 35s -> 53m 27s (+22.6%)
aarch64-gnu-llvm-21-1: 53m 38s -> 1h 4m (+20.4%)
dist-armv7-linux: 1h 30m -> 1h 11m (-20.4%)
pr-check-1: 26m 33s -> 31m 33s (+18.8%)
dist-powerpc64-linux-gnu: 1h 16m -> 1h 30m (+18.0%)
dist-x86_64-llvm-mingw: 1h 47m -> 1h 29m (-17.3%)

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 · 2026-04-22T03:38:10Z

Finished benchmarking commit (f9988fe): 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
Improvements ✅ (secondary)	-0.0%	[-0.0%, -0.0%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 1.5%, secondary 1.3%)

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

	mean	range	count
Regressions ❌ (primary)	1.5%	[1.5%, 1.5%]	1
Regressions ❌ (secondary)	1.3%	[1.1%, 1.5%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	1.5%	[1.5%, 1.5%]	1

Cycles

Results (primary -2.1%, secondary -0.4%)

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)	3.6%	[3.6%, 3.6%]	1
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-4.4%	[-4.4%, -4.4%]	1
All ❌✅ (primary)	-2.1%	[-2.1%, -2.1%]	1

Binary size

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

Bootstrap: 489.594s -> 490.294s (0.14%)
Artifact size: 394.45 MiB -> 394.43 MiB (-0.00%)

nnethercote and others added 17 commits April 20, 2026 10:13

Use per-parent disambiguators

2e6a082

Fix incorrect let to const suggestion for pattern bindings

a687f0b

Flatten nested tuple destructuring

90c03d8

Remove AttributeLintKind::DocTestTakesList variant

2ccad45

Remove AttributeLintKind::DocTestUnknown variant

b1cc9a6

Remove AttributeLintKind::DocTestLiteral variant

33b896a

Remove AttributeLintKind::AttrCrateLevelOnly variant

a9f16fa

Remove AttributeLintKind::DoNotRecommendDoesNotExpectArgs variant

6b78288

Remove AttributeLintKind::UnknownCrateTypesSuggestion variant

940d0f8

Reorder emails of Guillaume Gomez so it appears as its primary email …

80777dd

…and not the old one

Rollup merge of rust-lang#155590 - GuillaumeGomez:rm-attributelintkin…

79e2ff7

…d, r=JonathanBrouwer Remove AttributeLintKind variants - part 5 Part of rust-lang#153099. r? @JonathanBrouwer

rust-bors Bot added the rollup A PR which is a rollup label Apr 21, 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-review Status: Awaiting review from the assignee but also interested parties. labels Apr 21, 2026

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rust-bors Bot added merged-by-bors This PR was explicitly merged by bors. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Apr 22, 2026

rust-bors Bot merged commit f9988fe into rust-lang:main Apr 22, 2026
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rustbot added this to the 1.97.0 milestone Apr 22, 2026

This was referenced Apr 22, 2026

Make lowering incremental, take 3/N #142830

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Do not modify resolver outputs during lowering #155460

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Rollup of 5 pull requests#155611

Rollup of 5 pull requests#155611
rust-bors[bot] merged 17 commits intorust-lang:mainfrom
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rust-timer commented Apr 22, 2026

Overall result: ✅ improvements - no action needed

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