Don't normalize higher-ranked assumptions if they're not used

[compiler-errors]

See the comment in the code.

Normalizing these assumptions may cause us to register things like new placeholder outlives obligations that cause higher-ranked lifetime errors, and this is problematic if we're not even using these assumptions in borrowck.

Fixes #147244
Fixes #147285

[rustbot]

r? @fee1-dead

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[jackh726]

@bors r+ rollup=never

[bors]

📌 Commit e3f1046 has been approved by jackh726

It is now in the queue for this repository.

[bors]

⌛ Testing commit e3f1046 with merge 7950f24...

[bors]

☀️ Test successful - checks-actions
Approved by: jackh726
Pushing 7950f24 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 595b9a4 (parent) -> 7950f24 (this PR)

Test differences

Show 16 test diffs

Stage 1

• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions-2.rs#hr: [missing] -> pass (J0)
• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions-2.rs#stock: [missing] -> pass (J0)
• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions.rs#hr: [missing] -> pass (J0)
• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions.rs#stock: [missing] -> pass (J0)

Stage 2

• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions-2.rs#hr: [missing] -> pass (J1)
• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions-2.rs#stock: [missing] -> pass (J1)
• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions.rs#hr: [missing] -> pass (J1)
• [ui] tests/ui/async-await/higher-ranked-normalize-assumptions.rs#stock: [missing] -> pass (J1)

Additionally, 8 doctest diffs were found. These are ignored, as they are noisy.

Job group index

• J0: x86_64-gnu-llvm-20-3
• J1: aarch64-apple, aarch64-gnu, aarch64-gnu-llvm-20-1, 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-20, 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 7950f244e7ef55b61a83d12f4662be643cd182d6 --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. dist-aarch64-msvc: 5274.6s -> 6397.1s (21.3%)
2. test-various: 4011.5s -> 4749.2s (18.4%)
3. i686-gnu-nopt-1: 7051.7s -> 8138.1s (15.4%)
4. dist-aarch64-apple: 5608.3s -> 6359.8s (13.4%)
5. aarch64-msvc-2: 4604.2s -> 5220.5s (13.4%)
6. aarch64-apple: 9620.4s -> 8432.2s (-12.4%)
7. pr-check-1: 1400.5s -> 1571.3s (12.2%)
8. aarch64-gnu-llvm-20-2: 2153.3s -> 2375.8s (10.3%)
9. x86_64-gnu-tools: 3368.6s -> 3712.1s (10.2%)
10. x86_64-gnu: 6808.1s -> 7455.1s (9.5%)

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 (7950f24): 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)	-0.4%	[-0.6%, -0.3%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary -1.0%)

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
Improvements ✅ (secondary)	-1.0%	[-1.0%, -1.0%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (primary -2.4%, secondary 1.8%)

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)	1.8%	[1.1%, 2.5%]	2
Improvements ✅ (primary)	-2.4%	[-2.4%, -2.4%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.4%	[-2.4%, -2.4%]	1

Binary size

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

Bootstrap: 470.682s -> 473.406s (0.58%)
Artifact size: 388.33 MiB -> 388.33 MiB (-0.00%)