Unify two `for_each_relevant_impl` methods by adwinwhite · Pull Request #159836 · rust-lang/rust

adwinwhite · 2026-07-24T13:04:21Z

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We have two similar methods on tcx with the same name. It's confusing.

r? lcnr

lcnr · 2026-07-29T08:00:33Z

fun divergence here 🤔

@rustbot author

rustbot · 2026-07-29T08:00:37Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

lcnr · 2026-07-29T08:01:59Z

+            | ty::Never
+            | ty::Tuple(_)
+            | ty::UnsafeBinder(_) => {
+                if let Some(simp) = ty::fast_reject::simplify_type(


oh, that's existing, but we should really make this an unwrap. We shouldn't allow not having a simplified type here as that indicates a bug 🤔

View changes since the review

lcnr · 2026-07-29T08:03:13Z

+            ty::Alias(ty::IsRigid::Yes, _) | ty::Placeholder(..) | ty::Error(_) => (),
+            // FIXME(-Znext-solver=no): Need to support aliases not marked as
+            // rigid for the old solver.
+            ty::Alias(ty::IsRigid::No, _) | ty::Param(_) | ty::Infer(ty::TyVar(_)) => (),


and that's why old and new impl diverge, we should never call for_each_relevant_impl for infer vars 🤔 would be good to keep TyVar as an ICE and handle it at its call sites

View changes since the review

for_each_relevant_impl is used a lot in diagnostics. Denying ty var would complicate them a bit.

hmm, I do feel like listing applicable impls for ty vars is kind of meh 🤷 I guess we can actually just iterate all impls when used for a ty var and say how that should never be done in the happy path or sth?

you mean an early return? we currently iterate all impls at the end, after matching self_ty.

ChayimFriedman2

You reverted #156295, please revert that.

View changes since this review

lcnr · 2026-07-30T08:32:11Z

@bors try @rust-timer queue

Unify two `for_each_relevant_impl` methods

lcnr · 2026-07-30T08:32:23Z

@bors cancel

rust-bors · 2026-07-30T08:32:26Z

❗ There is currently no auto build in progress on this PR.

Hint: There is a pending try build on this PR. Maybe you meant to cancel it? You can do that using @bors try cancel.

rust-bors · 2026-07-30T08:47:55Z

💔 Test for 7017c2c failed: CI. Failed job:

try - dist-x86_64-linux-quick (web logs, enhanced plaintext logs)

adwinwhite · 2026-07-31T04:02:04Z

@bors try @rust-timer queue

Unify two `for_each_relevant_impl` methods

rust-bors · 2026-07-31T06:12:26Z

☀️ Try build successful (CI)
Build commit: 9951eb3 (9951eb3792e6ea9f7cd97c90f0371d5a62024a14)
Base parent: 8ab9fdf (8ab9fdff5a91b9f2b5ed57fb0275452d9a0d0280)

rust-timer · 2026-07-31T06:54:24Z

Finished benchmarking commit (9951eb3): 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 rustc-perf
@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)	0.2%	[0.2%, 0.3%]	10
Improvements ✅ (primary)	-4.0%	[-20.7%, -0.2%]	11
Improvements ✅ (secondary)	-0.6%	[-0.8%, -0.3%]	5
All ❌✅ (primary)	-3.1%	[-20.7%, 0.2%]	14

Max RSS (memory usage)

Results (primary -1.4%, secondary 0.5%)

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)	5.8%	[5.8%, 5.8%]	1
Improvements ✅ (primary)	-1.4%	[-2.4%, -0.5%]	8
Improvements ✅ (secondary)	-0.5%	[-0.7%, -0.4%]	5
All ❌✅ (primary)	-1.4%	[-2.4%, -0.5%]	8

Cycles

Results (primary -2.3%, 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)	1.1%	[0.4%, 1.6%]	7
Regressions ❌ (secondary)	0.6%	[0.5%, 0.7%]	3
Improvements ✅ (primary)	-6.2%	[-15.6%, -0.9%]	6
Improvements ✅ (secondary)	-1.9%	[-5.9%, -0.4%]	8
All ❌✅ (primary)	-2.3%	[-15.6%, 1.6%]	13

Binary size

Results (primary -0.0%, secondary -0.0%)

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)	-	-	0
Improvements ✅ (primary)	-0.0%	[-0.1%, -0.0%]	23
Improvements ✅ (secondary)	-0.0%	[-0.1%, -0.0%]	5
All ❌✅ (primary)	-0.0%	[-0.1%, -0.0%]	23

Bootstrap: 492.09s -> 490.67s (-0.29%)
Artifact size: 390.63 MiB -> 390.44 MiB (-0.05%)

lcnr · 2026-07-31T12:11:20Z

@bors r+ rollup=never

rust-bors · 2026-07-31T12:11:22Z

📌 Commit a070b70 has been approved by lcnr

It is now in the queue for this repository.

rust-bors · 2026-07-31T17:23:08Z

☀️ Test successful - CI
Approved by: lcnr
Duration: 3h 22m 6s
Pushing 64af19d to main...

github-actions · 2026-07-31T17:26:25Z

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 fc0f51f (parent) -> 64af19d (this PR)

Test differences

No test diffs found

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 64af19d44c63587455c76f484ce76261a9971e96 --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-gcc-core-tests: 7m 34s -> 14m 9s (+86.9%)
x86_64-gnu-llvm-21-1: 38m 50s -> 57m 41s (+48.5%)
x86_64-gnu-gcc: 49m 24s -> 1h 7m (+36.1%)
dist-arm-linux-musl: 1h 20m -> 1h 47m (+34.7%)
x86_64-gnu-aux: 1h 47m -> 2h 25m (+34.5%)
x86_64-msvc-2: 2h 36m -> 1h 47m (-31.2%)
dist-x86_64-msvc-alt: 2h 13m -> 2h 50m (+27.2%)
pr-check-1: 26m 21s -> 33m 20s (+26.5%)
dist-various-2: 33m 50s -> 42m 30s (+25.6%)
dist-arm-linux-gnueabi: 1h 11m -> 1h 29m (+24.8%)

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 · 2026-07-31T18:05:53Z

Finished benchmarking commit (64af19d): comparison URL.

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

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)	0.2%	[0.2%, 0.2%]	4
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	9
Improvements ✅ (primary)	-2.8%	[-20.6%, -0.2%]	16
Improvements ✅ (secondary)	-0.5%	[-0.8%, -0.3%]	7
All ❌✅ (primary)	-2.2%	[-20.6%, 0.2%]	20

Max RSS (memory usage)

Results (primary -1.0%, 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)	2.7%	[2.4%, 2.9%]	2
Regressions ❌ (secondary)	1.5%	[0.7%, 2.2%]	2
Improvements ✅ (primary)	-1.5%	[-3.4%, -0.4%]	16
Improvements ✅ (secondary)	-2.9%	[-5.8%, -0.4%]	5
All ❌✅ (primary)	-1.0%	[-3.4%, 2.9%]	18

Cycles

Results (primary -3.1%, 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)	0.7%	[0.6%, 0.8%]	2
Regressions ❌ (secondary)	2.1%	[0.9%, 3.8%]	4
Improvements ✅ (primary)	-3.8%	[-16.0%, -0.6%]	11
Improvements ✅ (secondary)	-0.8%	[-1.7%, -0.5%]	10
All ❌✅ (primary)	-3.1%	[-16.0%, 0.8%]	13

Binary size

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

Bootstrap: 491.246s -> 492.106s (0.18%)
Artifact size: 390.66 MiB -> 390.46 MiB (-0.05%)

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 24, 2026

rustbot assigned lcnr Jul 24, 2026

rustbot added T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. WG-trait-system-refactor The Rustc Trait System Refactor Initiative (-Znext-solver) labels Jul 24, 2026