Consider errors in MIR as impossible predicates to empty the body.

[cjgillot]

The ICEs come from elaborating drops or performing state transform in MIR bodies that fail typeck or borrowck.

If the body is tainted, replace it with unreachable.

Fixes #122630
Fixes #122904
Fixes #125185
Fixes #139556

[rustbot]

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

This PR changes a file inside tests/crashes. If a crash was fixed, please move into the corresponding ui subdir and add 'Fixes #' to the PR description to autoclose the issue upon merge.

[rustbot]

r? @BoxyUwU

rustbot has assigned @BoxyUwU.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[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.

[oli-obk]

r? @oli-obk

@bors try @rust-timer queue

r=me (with rollup if perf is clean)

[rust-bors]

☀️ Try build successful (CI)
Build commit: 9a1f375 (9a1f3754dbbdb47b7ee951aa0595d8d436ec5146, parent: dd7fda570040e8a736f7d8bc28ddd1b444aabc82)

[rust-timer]

Finished benchmarking commit (9a1f375): comparison URL.

Overall result: no relevant changes - no action needed

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.

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

Instruction count

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

Max RSS (memory usage)

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

Cycles

Results (secondary -2.8%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.8%	[-2.8%, -2.8%]	1
All ❌✅ (primary)	-	-	0

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

Bootstrap: 472.936s -> 471.976s (-0.20%)
Artifact size: 389.95 MiB -> 389.98 MiB (0.01%)

[cjgillot]

@bors r=oli-obk rollup

[bors]

📌 Commit 3934fc9 has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3934fc9 with merge 7e4b8d7...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 7e4b8d7 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 6710835 (parent) -> 7e4b8d7 (this PR)

Test differences

Show 18 test diffs

Stage 1

• [crashes] tests/crashes/122630.rs: pass -> [missing] (J1)
• [crashes] tests/crashes/122904-2.rs: pass -> [missing] (J1)
• [crashes] tests/crashes/125185.rs: pass -> [missing] (J1)
• [crashes] tests/crashes/139556.rs: pass -> [missing] (J1)
• [ui] tests/ui/coroutine/moved-twice.rs: [missing] -> pass (J1)
• [ui] tests/ui/type-alias-impl-trait/recursive-drop-elaboration-2.rs: [missing] -> pass (J1)
• [ui] tests/ui/type-alias-impl-trait/recursive-drop-elaboration.rs: [missing] -> pass (J1)
• [ui] tests/ui/type-alias-impl-trait/type-error-drop-elaboration.rs: [missing] -> pass (J1)

Stage 2

• [ui] tests/ui/coroutine/moved-twice.rs: [missing] -> pass (J0)
• [ui] tests/ui/type-alias-impl-trait/recursive-drop-elaboration-2.rs: [missing] -> pass (J0)
• [ui] tests/ui/type-alias-impl-trait/recursive-drop-elaboration.rs: [missing] -> pass (J0)
• [ui] tests/ui/type-alias-impl-trait/type-error-drop-elaboration.rs: [missing] -> pass (J0)
• [crashes] tests/crashes/122630.rs: pass -> [missing] (J2)
• [crashes] tests/crashes/122904-2.rs: pass -> [missing] (J2)
• [crashes] tests/crashes/125185.rs: pass -> [missing] (J2)
• [crashes] tests/crashes/139556.rs: pass -> [missing] (J2)

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

Job group index

• J0: 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
• J1: x86_64-gnu-llvm-20-3
• J2: 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-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 7e4b8d702fedccc9c7803773a22c2e053ac3b004 --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. aarch64-apple: 5586.2s -> 4910.0s (-12.1%)
2. dist-x86_64-apple: 6636.1s -> 7372.4s (11.1%)
3. x86_64-gnu-nopt: 7768.2s -> 7102.4s (-8.6%)
4. dist-aarch64-msvc: 5478.2s -> 5850.5s (6.8%)
5. i686-gnu-nopt-1: 7636.1s -> 7181.6s (-6.0%)
6. dist-i686-mingw: 10003.3s -> 9482.8s (-5.2%)
7. tidy: 191.8s -> 182.8s (-4.7%)
8. dist-loongarch64-linux: 5170.0s -> 5410.1s (4.6%)
9. dist-armv7-linux: 5185.7s -> 4955.8s (-4.4%)
10. aarch64-gnu-llvm-20-2: 2250.2s -> 2348.1s (4.4%)

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 (7e4b8d7): 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 6.0%)

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

	mean	range	count
Regressions ❌ (primary)	6.0%	[3.7%, 8.4%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	6.0%	[3.7%, 8.4%]	2

Cycles

Results (primary -4.8%, secondary 2.9%)

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)	2.9%	[2.2%, 4.2%]	3
Improvements ✅ (primary)	-4.8%	[-4.8%, -4.8%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-4.8%	[-4.8%, -4.8%]	1

Binary size

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

Bootstrap: 470.892s -> 471.863s (0.21%)
Artifact size: 387.92 MiB -> 387.93 MiB (0.00%)