consider item bounds for non-yet-defined opaque types

[lcnr]

Based on #140405.

fixes rust-lang/trait-system-refactor-initiative#182
fixes rust-lang/trait-system-refactor-initiative#196
fixes rust-lang/trait-system-refactor-initiative#205

there's some jank here, see rust-lang/trait-system-refactor-initiative#229

Design

If the self type is an inference variable which has been sub-unified with am opaque type, we need to incompletely guide inference to avoid breakage.

In this case, we

• look at the item bounds of all sub-unified opaque types, and
• blanket impls which do not constrain the self type

Even if there are applicable candidates, we always force their certainty to be Maybe, so they will always have to be reproven once we've constrained the inference variable.

This is a bit iffy, see the added tests.

r? @BoxyUwU

[bors]

☔ The latest upstream changes (presumably #146333) made this pull request unmergeable. Please resolve the merge conflicts.

[lcnr]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 86e299c (86e299c4ac5f5f35d68e41729747c56e53dc5001, parent: 7ad23f43a225546c095123de52cc07d8719f8e2b)

[rust-timer]

Finished benchmarking commit (86e299c): 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)	0.4%	[0.1%, 0.8%]	10
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.4%)

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

	mean	range	count
Regressions ❌ (primary)	2.4%	[2.4%, 2.4%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	1

Cycles

Results (secondary 3.2%)

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)	3.2%	[3.1%, 3.3%]	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: 469.26s -> 469.264s (0.00%)
Artifact size: 387.51 MiB -> 387.71 MiB (0.05%)

[lcnr]

damn, these regressions are tiny. gamer!

[lcnr]

@bors r=BoxyUwU

[bors]

📌 Commit fba7203 has been approved by BoxyUwU

It is now in the queue for this repository.

[BoxyUwU]

gamer!

[rustbot]

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]

@bors r=BoxyUwU

[bors]

📌 Commit cf224ea has been approved by BoxyUwU

It is now in the queue for this repository.

[Zalathar]

Giving this a priority bump over the rollup=iffy PR in case the rollup fails.

@bors p=1

[bors]

⌛ Testing commit cf224ea with merge a171994...

[bors]

☀️ Test successful - checks-actions
Approved by: BoxyUwU
Pushing a171994 to master...

[github-actions]

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 408eacf (parent) -> a171994 (this PR)

Test differences

Show 63 test diffs

Stage 1

• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket-2.rs#current: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket-2.rs#next: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket-3.rs: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket.rs#current: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket.rs#next: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/multiple-opaques-ambig.rs: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/multiple-opaques-ok.rs: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/no-rigid-alias.rs: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/use-blanket-impl.rs#current: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/use-blanket-impl.rs#next: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound-over-blanket-impl.rs#current: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound-over-blanket-impl.rs#next: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound.rs#current: [missing] -> pass (J0)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound.rs#next: [missing] -> pass (J0)

Stage 2

• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket-2.rs#current: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket-2.rs#next: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket-3.rs: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket.rs#current: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/avoid-inference-constraints-from-blanket.rs#next: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/multiple-opaques-ambig.rs: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/multiple-opaques-ok.rs: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/no-rigid-alias.rs: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/use-blanket-impl.rs#current: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/use-blanket-impl.rs#next: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound-over-blanket-impl.rs#current: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound-over-blanket-impl.rs#next: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound.rs#current: [missing] -> pass (J1)
• [ui] tests/ui/impl-trait/non-defining-uses/use-item-bound.rs#next: [missing] -> pass (J1)

Additionally, 35 doctest diffs were found. These are ignored, as they are noisy.

Job group index

• J0: x86_64-gnu-llvm-19-3, x86_64-gnu-llvm-20-3
• J1: aarch64-apple, aarch64-gnu, aarch64-gnu-llvm-19-1, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, test-various, x86_64-gnu, x86_64-gnu-debug, x86_64-gnu-llvm-19, x86_64-gnu-llvm-19-2, x86_64-gnu-llvm-20-2, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard a171994070dc18c3a32fc1aa2d98cf03ae96b63e --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

1. x86_64-gnu-llvm-19-1: 3411.4s -> 3977.3s (16.6%)
2. i686-gnu-nopt-1: 7333.0s -> 8168.3s (11.4%)
3. aarch64-gnu-debug: 3781.4s -> 4183.8s (10.6%)
4. x86_64-rust-for-linux: 2621.1s -> 2870.0s (9.5%)
5. i686-gnu-2: 5538.9s -> 5975.8s (7.9%)
6. x86_64-gnu-llvm-20-2: 5479.7s -> 5895.7s (7.6%)
7. dist-powerpc64le-linux-musl: 5091.8s -> 5461.9s (7.3%)
8. pr-check-1: 1362.7s -> 1458.6s (7.0%)
9. x86_64-gnu-miri: 4508.8s -> 4825.9s (7.0%)
10. dist-armhf-linux: 5083.2s -> 4734.4s (-6.9%)

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]

Finished benchmarking commit (a171994): 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%	[0.2%, 0.8%]	11
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.4%	[-0.4%, -0.4%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (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)	1.0%	[1.0%, 1.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-4.0%	[-4.5%, -3.4%]	2
All ❌✅ (primary)	-	-	0

Cycles

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

Binary size

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

Bootstrap: 468.519s -> 469.518s (0.21%)
Artifact size: 387.84 MiB -> 388.08 MiB (0.06%)

[panstromek]

perf triage:

tt-muncher, ucd and tuple-stress all look like noise to me. The rest is in new-solver, which is still WIP and not enabled by default.

@rustbot label: +perf-regression-triaged