std: fix SplitPaths regression

[joboet]

Fixes #146045 by defining the TAIT more precisely, ensuring that 'a does not need to be live on drop.

[rustbot]

r? @tgross35

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[Mark-Simulacrum]

r=me

[joboet]

@bors r=@Mark-Simulacrum

[bors]

📌 Commit 6d8d952 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bors]

⌛ Testing commit 6d8d952 with merge f73bcd5...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing f73bcd5 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 564ee21 (parent) -> f73bcd5 (this PR)

Test differences

Show 4 test diffs

Stage 1

• [ui] tests/ui/type-alias-impl-trait/split-paths-may-dangle.rs: [missing] -> pass (J1)

Stage 2

• [ui] tests/ui/type-alias-impl-trait/split-paths-may-dangle.rs: [missing] -> pass (J0)

Additionally, 2 doctest diffs were found. These are ignored, as they are noisy.

Job group index

• J0: 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
• J1: x86_64-gnu-llvm-19-3, x86_64-gnu-llvm-20-3

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard f73bcd50a433b7c17225ca98b44064236e7e84b3 --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-linux: 8400.8s -> 5712.7s (-32.0%)
2. dist-apple-various: 4008.5s -> 3214.0s (-19.8%)
3. x86_64-rust-for-linux: 3212.9s -> 2628.1s (-18.2%)
4. x86_64-gnu-llvm-19: 2767.5s -> 2366.6s (-14.5%)
5. aarch64-gnu-debug: 4999.9s -> 4301.9s (-14.0%)
6. i686-gnu-2: 6228.5s -> 5401.6s (-13.3%)
7. pr-check-2: 2423.7s -> 2130.8s (-12.1%)
8. i686-gnu-nopt-1: 8383.5s -> 7372.9s (-12.1%)
9. test-various: 5124.2s -> 4536.0s (-11.5%)
10. arm-android: 6392.0s -> 5750.3s (-10.0%)

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 (f73bcd5): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (primary 7.7%)

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

	mean	range	count
Regressions ❌ (primary)	7.7%	[7.7%, 7.7%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	7.7%	[7.7%, 7.7%]	1

Cycles

Results (primary -2.0%)

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)	-2.0%	[-2.0%, -2.0%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.0%	[-2.0%, -2.0%]	1

Binary size

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

Bootstrap: 468.632s -> 468.46s (-0.04%)
Artifact size: 388.55 MiB -> 388.57 MiB (0.01%)