Rollup of 6 pull requests #150798

matthiaskrgr · 2026-01-08T06:27:57Z

Successful merges:

MGCA: Support tuple expressions as direct const arguments #150675 (MGCA: Support tuple expressions as direct const arguments)
enrich error info when tries to dlopen Enzyme #150696 (enrich error info when tries to dlopen Enzyme)
tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: Not needed so remove #150747 (tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: Not needed so remove)
Fix alloc_error_handler signature mismatch #150757 (Fix alloc_error_handler signature mismatch)
Stabilize slice::element_offset #150777 (Stabilize slice::element_offset)
Remove out of date FIXME comment. #150791 (Remove out of date FIXME comment.)

It was added in ddee45e when SIGPIPE was controlled with an attribute on `fn main()` which meant it could also be combined with `#[rustc_main]`: #[unix_sigpipe = "sig_dfl"] #[rustc_main] fn rustc_main() { It stopped being needed cde0cde when `#[unix_sigpipe = "..."]` was replaced by `-Zon-broken-pipe=...`. And it will not be needed when `-Zon-broken-pipe=...` is replaced by an Externally Implementable Item. Let's remove this test.

In rust-lang#127273 I added a test and a FIXME comment pointing out how it does the wrong thing. In the next commit I fixed the problem but forgot to remove the FIXME comment, whoops.

@BoxyUwU

MGCA: Support tuple expressions as direct const arguments Tracking issue: rust-lang#132980 Fixes rust-lang#133965 Fixes rust-lang#150613 r? @BoxyUwU

enrich error info when tries to dlopen Enzyme In rust-lang#127273 I added a test and a FIXME comment pointing out how it does the wrong thing. In the next commit I fixed the problem but forgot to remove the FIXME comment, whoops.

@ZuseZ4

tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: Not needed so remove related: rust-lang#145899 (comment) print error from EnzymeWrapper::get_or_init(sysroot) as a note r? @ZuseZ4 e.g. 1. when libEnzyme not found ```shell $ rustc +stage1 -Z autodiff=Enable -C lto=fat src/main.rs error: autodiff backend not found in the sysroot: failed to find a `libEnzyme-21` folder in the sysroot candidates: * /Volumes/WD_BLACK_SN850X_HS_1TB/rust-lang/rust/build/aarch64-apple-darwin/stage1/lib | = note: it will be distributed via rustup in the future ``` 2. when could not load libEnzyme successfully ```shell rustc +stage1 -Z autodiff=Enable -C lto=fat src/main.rs error: failed to load our autodiff backend: DlOpen { source: "dlopen(/Volumes/WD_BLACK_SN850X_HS_1TB/rust-lang/rust/build/aarch64-apple-darwin/stage1/lib/rustlib/aarch64-apple-darwin/lib/libEnzyme-21.dylib, 0x0005): tried: \'/Volumes/WD_BLACK_SN850X_HS_1TB/rust-lang/rust/build/aarch64-apple-darwin/stage1/lib/rustlib/aarch64-apple-darwin/lib/libEnzyme-21.dylib\' (slice is not valid mach-o file), \'/System/Volumes/Preboot/Cryptexes/OS/Volumes/WD_BLACK_SN850X_HS_1TB/rust-lang/rust/build/aarch64-apple-darwin/stage1/lib/rustlib/aarch64-apple-darwin/lib/libEnzyme-21.dylib\' (no such file), \'/Volumes/WD_BLACK_SN850X_HS_1TB/rust-lang/rust/build/aarch64-apple-darwin/stage1/lib/rustlib/aarch64-apple-darwin/lib/libEnzyme-21.dylib\' (slice is not valid mach-o file)" } ```

Fix `alloc_error_handler` signature mismatch It was added in ddee45e ([here](https://github.com/rust-lang/rust/pull/97802/changes#diff-85dc642a7bdad363a9e37d2491230280fcd977391ba7a242bda2da9ddb55f654) to be specific) when SIGPIPE was controlled with an attribute on `fn main()` which meant it could also be combined with `#[rustc_main]`: #[unix_sigpipe = "sig_dfl"] #[rustc_main] fn rustc_main() { The test stopped being needed in cde0cde when `#[unix_sigpipe = "..."]` was replaced by `-Zon-broken-pipe=...`. And it will not be needed when `-Zon-broken-pipe=...` is replaced by an Externally Implementable Item (see rust-lang#150591). Let's remove this test. Tracking issue: - rust-lang#150588

Stabilize `slice::element_offset` [slice::element_offset](https://doc.rust-lang.org/std/primitive.slice.html#method.element_offset) Partially stabilizes rust-lang#126769 (substr_range). [FCP completed](rust-lang#126769 (comment)) The other methods are [stalled because of the new range types](rust-lang#126769 (comment)), but this method doesn't use ranges.

Remove out of date FIXME comment. Commit rust-lang#147526 removed the following code and replaced it with the `AllocatorMethod`. However, its input is empty, resulting in behavior inconsistent with the previous code. ```rust create_wrapper_function( tcx, &cx, &mangle_internal_symbol(tcx, "__rust_alloc_error_handler"), Some(&mangle_internal_symbol(tcx, alloc_error_handler_name(alloc_error_handler_kind))), &[usize, usize], // size, align None, true, &CodegenFnAttrs::new(), ); ``` resolves rust-lang#150755

matthiaskrgr · 2026-01-08T06:28:09Z

@bors r+ rollup=never p=5

rust-bors · 2026-01-08T06:28:13Z

📌 Commit bfec56b has been approved by matthiaskrgr

It is now in the queue for this repository.

rust-bors · 2026-01-08T09:52:47Z

☀️ Test successful - CI
Approved by: matthiaskrgr
Pushing bca37a2 to main...

rust-timer · 2026-01-08T09:54:30Z

📌 Perf builds for each rolled up PR:

PR#	Message	Perf Build Sha
#150675	MGCA: Support tuple expressions as direct const arguments	`114ddb120d3b825abcf563a0e1fd8289e3c11231` (link)
#150696	enrich error info when tries to dlopen Enzyme	`223f2d17533921240d0fcf949345d88fd6635a50` (link)
#150747	tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: Not nee…	`076205a64463663589df78200b73d1ac8073add2` (link)
#150757	Fix `alloc_error_handler` signature mismatch	`6c5495b3e3f532e80840d40f1e7a8cafc6a7779a` (link)
#150777	Stabilize `slice::element_offset`	`62ed8eb16d07b8cc2286b6d7b87366e3bc8d0416` (link)
#150791	Remove out of date FIXME comment.	`74fc1a09129d95938190a8d23947093b55a782f8` (link)

previous master: 598c7bde38

In the case of a perf regression, run the following command for each PR you suspect might be the cause: @rust-timer build $SHA

github-actions · 2026-01-08T09:55:23Z

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 598c7bd (parent) -> bca37a2 (this PR)

Test differences

Show 69 test diffs

Stage 1

[crashes] tests/crashes/133965.rs: pass -> [missing] (J0)
[ui] tests/ui/const-generics/mgca/adt_expr_arg_tuple_expr_complex.rs: [missing] -> pass (J0)
[ui] tests/ui/const-generics/mgca/adt_expr_arg_tuple_expr_simple.rs: [missing] -> pass (J0)
[ui] tests/ui/duplicate/multiple-types-with-same-name-and-derive-default-133965.rs: [missing] -> pass (J0)
[ui] tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: pass -> [missing] (J0)

Stage 2

[ui] tests/ui/const-generics/mgca/adt_expr_arg_tuple_expr_complex.rs: [missing] -> pass (J1)
[ui] tests/ui/const-generics/mgca/adt_expr_arg_tuple_expr_simple.rs: [missing] -> pass (J1)
[crashes] tests/crashes/133965.rs: pass -> [missing] (J2)
[ui] tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: ignore (only executed when the target family is unix (because SIGPIPE is a unix thing)) -> [missing] (J3)
[crashes] tests/crashes/133965.rs: ignore (ignored if rustc wasn't built with debug assertions) -> [missing] (J4)
[ui] tests/ui/duplicate/multiple-types-with-same-name-and-derive-default-133965.rs: [missing] -> ignore (ignored if rustc wasn't built with debug assertions) (J4)
[ui] tests/ui/duplicate/multiple-types-with-same-name-and-derive-default-133965.rs: [missing] -> pass (J5)
[ui] tests/ui/runtime/on-broken-pipe/with-rustc_main.rs: pass -> [missing] (J6)

Additionally, 56 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard bca37a20bd376ce3fd138e7cdee7fe704e0f8814 --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

dist-apple-various: 4053.6s -> 3524.1s (-13.1%)
x86_64-gnu-miri: 5366.8s -> 4798.5s (-10.6%)
aarch64-apple: 10709.4s -> 9577.3s (-10.6%)
dist-powerpc-linux: 5559.5s -> 4993.8s (-10.2%)
x86_64-msvc-ext2: 6028.7s -> 5424.6s (-10.0%)
dist-aarch64-msvc: 5827.0s -> 6344.1s (+8.9%)
x86_64-gnu: 8421.7s -> 7760.7s (-7.8%)
x86_64-gnu-llvm-21-3: 7152.8s -> 6603.3s (-7.7%)
pr-check-1: 1920.6s -> 1785.4s (-7.0%)
i686-gnu-1: 8198.8s -> 8773.0s (+7.0%)

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 · 2026-01-08T10:35:32Z

Finished benchmarking commit (bca37a2): 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)	-0.3%	[-0.6%, -0.1%]	4
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -1.7%)

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)	-1.7%	[-1.7%, -1.7%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.7%	[-1.7%, -1.7%]	1

Cycles

Results (primary -2.3%, secondary -3.0%)

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)	-2.3%	[-2.8%, -1.7%]	3
Improvements ✅ (secondary)	-3.0%	[-3.0%, -3.0%]	1
All ❌✅ (primary)	-2.3%	[-2.8%, -1.7%]	3

Binary size

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

Bootstrap: 474.717s -> 475.924s (0.25%)
Artifact size: 390.81 MiB -> 390.87 MiB (0.01%)

sgasho and others added 16 commits January 4, 2026 22:56

enrich error info when tries to dlopen Enzyme

d7fa6e5

Modified to output error messages appropriate to the situation

14ac6a1

MGCA: Support tuple expressions as direct const arguments

af76a24

Add span field for ConstArg

d572e6d

Use parent's identity_args to instantiate the type of const param

cb1de29

Bless other tests

6c2dc40

Fix alloc_error_handler signature mismatch

f02ed7b

Stabilize slice::element_offset

5548a84

Remove out of date FIXME comment.

65756be

In rust-lang#127273 I added a test and a FIXME comment pointing out how it does the wrong thing. In the next commit I fixed the problem but forgot to remove the FIXME comment, whoops.

Rollup merge of rust-lang#150675 - mgca/tuple-expr, r=BoxyUwU

db2ab90

MGCA: Support tuple expressions as direct const arguments Tracking issue: rust-lang#132980 Fixes rust-lang#133965 Fixes rust-lang#150613 r? @BoxyUwU

Rollup merge of rust-lang#150696 - rm-FIXME, r=ZuseZ4

bb27147

enrich error info when tries to dlopen Enzyme In rust-lang#127273 I added a test and a FIXME comment pointing out how it does the wrong thing. In the next commit I fixed the problem but forgot to remove the FIXME comment, whoops.

rust-bors bot added the rollup A PR which is a rollup label Jan 8, 2026

rust-bors bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jan 8, 2026

rust-bors bot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 8, 2026

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rust-bors bot added the merged-by-bors This PR was explicitly merged by bors. label Jan 8, 2026

rust-bors bot merged commit bca37a2 into rust-lang:main Jan 8, 2026
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rustbot added this to the 1.94.0 milestone Jan 8, 2026

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Test differences

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Overall result: ✅ improvements - no action needed

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