Fast path for stalled obligations on self ty

[compiler-errors]

If we see that the self type of a goal is an infer var, then don't try to compute the goal at all, since we know that it'll be forced ambiguous.

This is currently only implemented when there are no opaques in the environment. We could extend it to check that the self type is not related to any already defined opaques via subtyping, but I'll leave that as a follow-up.

---

Also stall coerce and subtype predicates if both of their vars are not resolved to concrete types.

---

Also, we don't care if the goal is higher-ranked for the sized and copy/clone fast path. pulling this out into another PR.

r? lcnr

[compiler-errors]

@bors try @rust-timer queue

[bors]

⌛ Trying commit fb285af with merge fa369e6...

[bors]

☀️ Try build successful - checks-actions
Build commit: fa369e6 (fa369e6ddc2f81c31d5ded57f79518262940b5d6)

[rust-timer]

Finished benchmarking commit (fa369e6): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.5%	[0.5%, 0.5%]	1
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	6
Improvements ✅ (secondary)	-7.8%	[-29.0%, -0.1%]	15
All ❌✅ (primary)	-0.2%	[-0.3%, -0.1%]	6

Max RSS (memory usage)

Results (primary -1.0%, secondary -3.8%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.8%	[1.3%, 2.3%]	2
Improvements ✅ (primary)	-1.0%	[-1.0%, -1.0%]	1
Improvements ✅ (secondary)	-5.7%	[-8.7%, -4.7%]	6
All ❌✅ (primary)	-1.0%	[-1.0%, -1.0%]	1

Cycles

Results (secondary -12.3%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-12.3%	[-25.0%, -2.1%]	7
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 778.889s -> 779.678s (0.10%)
Artifact size: 368.42 MiB -> 366.35 MiB (-0.56%)

[rustbot]

Some changes occurred to the core trait solver

cc @rust-lang/initiative-trait-system-refactor

[bors]

☔ The latest upstream changes (presumably #141731) made this pull request unmergeable. Please resolve the merge conflicts.

[compiler-errors]

@bors2 try @rust-timer queue

[rust-bors]

⌛ Trying commit 9899464 with merge 039888f…

[rust-bors]

☀️ Try build successful (CI)
Build commit: 039888f (039888fc2fe51ca95ed23c75d554793192d536e0)

[rust-timer]

Finished benchmarking commit (039888f): comparison URL.

Overall result: ❌✅ regressions and improvements - please read the text below

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please fix the regressions and do another perf run. If the next run shows neutral or positive results, the label will be automatically removed.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.3%	[0.3%, 0.3%]	3
Improvements ✅ (primary)	-0.2%	[-0.2%, -0.2%]	3
Improvements ✅ (secondary)	-9.0%	[-50.3%, -0.2%]	20
All ❌✅ (primary)	-0.2%	[-0.2%, -0.2%]	3

Max RSS (memory usage)

Results (secondary 0.7%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.9%	[0.4%, 1.6%]	13
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.4%	[-0.5%, -0.4%]	3
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -7.9%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.2%	[0.7%, 1.7%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-9.1%	[-43.1%, -0.4%]	16
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 743.192s -> 742.766s (-0.06%)
Artifact size: 372.27 MiB -> 372.37 MiB (0.03%)

[lcnr]

@bors r+

[bors]

📌 Commit 9899464 has been approved by lcnr

It is now in the queue for this repository.

[bors]

⌛ Testing commit 9899464 with merge 9f0e5d9...

[bors]

☀️ Test successful - checks-actions
Approved by: lcnr
Pushing 9f0e5d9 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 f315e61 (parent) -> 9f0e5d9 (this PR)

Test differences

No test diffs found

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 9f0e5d963d05ebcf7ae1ca1f4bda3668c702acda --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-apple-1: 9670.2s -> 6827.2s (-29.4%)
2. dist-apple-various: 7761.4s -> 6565.9s (-15.4%)
3. dist-ohos-armv7: 3890.2s -> 4314.7s (10.9%)
4. dist-ohos-aarch64: 4158.8s -> 4557.0s (9.6%)
5. armhf-gnu: 4403.7s -> 4791.3s (8.8%)
6. dist-s390x-linux: 4735.5s -> 5132.6s (8.4%)
7. dist-powerpc64le-linux-musl: 4958.4s -> 5360.9s (8.1%)
8. dist-x86_64-apple: 8356.1s -> 9021.1s (8.0%)
9. i686-gnu-2: 5370.9s -> 5779.0s (7.6%)
10. i686-gnu-nopt-1: 7161.2s -> 7676.4s (7.2%)

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 (9f0e5d9): comparison URL.

Overall result: ❌✅ regressions and improvements - 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

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	0.2%	[0.2%, 0.2%]	1
Regressions ❌ (secondary)	0.6%	[0.1%, 1.3%]	14
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.1%]	25
Improvements ✅ (secondary)	-4.3%	[-50.3%, -0.0%]	43
All ❌✅ (primary)	-0.2%	[-0.3%, 0.2%]	26

Max RSS (memory usage)

Results (primary -2.5%, secondary 3.2%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	5.1%	[4.7%, 5.9%]	3
Improvements ✅ (primary)	-2.5%	[-2.5%, -2.5%]	1
Improvements ✅ (secondary)	-2.5%	[-2.5%, -2.5%]	1
All ❌✅ (primary)	-2.5%	[-2.5%, -2.5%]	1

Cycles

Results (secondary -14.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-15.9%	[-42.9%, -0.9%]	9
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 751.682s -> 751.346s (-0.04%)
Artifact size: 371.84 MiB -> 372.49 MiB (0.17%)

[panstromek]

perf triage:

Improvements outweigh regressions, those are mostly on stress tests. Some regressions also don't seem to be related, they just return back to state before #141652.

@rustbot label: +perf-regression-triaged