Rollup of 10 pull requests by Zalathar · Pull Request #162853 · rust-lang/rust

Zalathar · 2026-09-16T13:42:02Z

Successful merges:

implement const Iterator for Range #156216 (implement const Iterator for Range)
rustc: Tweak the effect of --jobs on frontend parallelism #160697 (rustc: Tweak the effect of --jobs on frontend parallelism)
Enable LLVM Thin LTO for LoongArch64 #162748 (Enable LLVM Thin LTO for LoongArch64)
Yeet the DeepRegionResolver (earlier called OpportunisticRegionResolver) #162769 (Yeet the DeepRegionResolver (earlier called OpportunisticRegionResolver))
Simplify ast::UseTreeKind #162794 (Simplify ast::UseTreeKind)
Cleanups related to RefDecodable #162800 (Cleanups related to RefDecodable)
wasm: fix ABI for enums with integer layout and ZST fields #162826 (wasm: fix ABI for enums with integer layout and ZST fields)
[rustc_public] Enhance PassMode API #159359 ([rustc_public] Enhance PassMode API)
Offload cmake cleanups #162196 (Offload cmake cleanups)
Add regression test for malformed RPITIT bound ICE with the new solver #162818 (Add regression test for malformed RPITIT bound ICE with the new solver)

It makes sense to put the top-level item first, before the use tree within the item. And it makes sense to have a single function-level comment explaining this rather than inline comments at the definition and every call site.

`is_public` is not relevant here.

changes in later commits need this case out of the way

Originally introduced in the Enzyme build and coppied around since, but without effect for a few years by now.

Replace the opaque representation of `PassMode::Cast` with a structured `CastTarget` type that exposes the register layout used by the platform ABI. Add `Uniform`, `Reg`, and `RegKind` types so tools can inspect how arguments are mapped to registers. Add `CastTarget::size()` and `Uniform::reg_count()` helpers. Add a test covering cast on args, returns, mixed register kinds, multiple arguments, and register exhaustion causing stack spill.

Expose argument ABI attributes through a structured type instead of opaque debug strings. ArgAttributes provides accessors for the extension mode (zero/sign-extend) and pointee alignment, which are needed by tools doing their own code generation. This removes all uses of Opaque from the abi module.

BREAKING CHANGE: `ValueAbi` is renamed to `ValueRepr` and the `LayoutShape::abi` field is renamed to `LayoutShape::value_repr`. The old name was misleading: this type does not describe how values are passed in function calls (that is `PassMode`), it is a hint for how backends should represent values (as scalars, vectors, or aggregates). This aligns with the internal rename from `Abi` to `BackendRepr`. Also fixes several doc comments that incorrectly claimed layout fields define calling behavior.

For !needs_drop types, this should allow decoding directly into the arena-allocated slice. For needs_drop types, the arena already collects into a SmallVec<T>, so this avoids an intermediate conversion from Vec<T> to SmallVec<T>.

These impls all match the impl provided by the into-arena macro.

The existing `codec` module contains a sea of impls that is hard to navigate. Extracting the RefDecodable parts into another file should make it easier to keep track of what is where. This commit tries to move everything as-is, so that `git diff --color-moved` can verify that nothing was changed. Subsequent commits will modify the moved code.

- Added and expanded comments - Renamed and clarified the impl-decodable macro - Sorted the macro list of Decodable impls

This commit replaces the existing boilerplate impls and the existing macro with a less confusing macro. Some unused impls have been removed.

It's simpler to make the `decode` method generic over `impl TyDecoder`.

Currently a `NodeId` is stored in a pair with each nested use tree. This commit changes the pair to a named type `UseTreeAndId`. In most places this doesn't make much difference but in the AST visitor it gets rid of several weird special cases.

Zalathar · 2026-09-16T13:42:18Z

Rollup of everything.

@bors r+ rollup=never p=5

rust-bors · 2026-09-16T13:42:20Z

📌 Commit 6f81ec1 has been approved by Zalathar

It is now in the queue for this repository.

JonathanBrouwer · 2026-09-16T13:47:44Z

Trying commonly failed jobs
@bors try jobs=dist-various-1,test-various,test-x86_64-gnu-aux,test-x86_64-gnu-llvm-21-3,test-x86_64-msvc-1,test-aarch64-apple-1,test-aarch64-apple-2,test-x86_64-mingw-1,test-i686-msvc,test-armhf-gnu

Rollup of 10 pull requests try-job: dist-various-1 try-job: test-various try-job: test-x86_64-gnu-aux try-job: test-x86_64-gnu-llvm-21-3 try-job: test-x86_64-msvc-1 try-job: test-aarch64-apple-1 try-job: test-aarch64-apple-2 try-job: test-x86_64-mingw-1 try-job: test-i686-msvc try-job: test-armhf-gnu

rust-bors · 2026-09-16T13:48:41Z

💔 Test for a5309a3 failed: CI, CI

JonathanBrouwer · 2026-09-16T13:51:04Z

???

rust-log-analyzer · 2026-09-16T14:38:50Z

The job test-x86_64-gnu-next-trait-solver-polonius failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

test [ui] tests/ui/test-attrs/tests-listing-format-json.rs ... ok
test [ui] tests/ui/thir-print/thir-flat-const-variant.rs ... ok
test [ui] tests/ui/test-attrs/tests-listing-format-terse.rs ... ok

Session terminated, killing shell...::group::Clock drift check
  local time: test [ui] tests/ui/thir-print/thir-tree-array-index.rs ... ok
##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
Wed Sep 16 14:32:43 UTC 2026
  network time: test [ui] tests/ui/thir-print/thir-flat.rs ... ok
test [ui] tests/ui/thir-print/thir-tree-field-expr-index.rs ... ok

Important

For more information how to resolve CI failures of this job, visit this link.

rust-bors · 2026-09-16T17:29:02Z

☀️ Test successful - CI
Approved by: Zalathar
Duration: 3h 3m 28s
Pushing 92801ed to main...

github-actions · 2026-09-16T17:32:11Z

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 e15cecc (parent) -> 92801ed (this PR)

Test differences

Show 604 test diffs

Stage 1

[ui] tests/ui/consts/const-for.rs: pass -> [missing] (J0)
[ui] tests/ui/traits/next-solver/rpit-in-trait-malformed-bound-globally-156100.rs: [missing] -> pass (J0)
[ui] tests/ui-fulldeps/rustc_public/check_abi_cast.rs: [missing] -> ignore (ignored when the bootstrapping stage is stage1) (J2)
[ui (polonius)] tests/ui/consts/const-for.rs: pass -> [missing] (J3)
[ui (polonius)] tests/ui/traits/next-solver/rpit-in-trait-malformed-bound-globally-156100.rs: [missing] -> pass (J3)

Stage 2

[ui] tests/ui-fulldeps/rustc_public/check_abi_cast.rs: [missing] -> pass (J1)
[ui] tests/ui/consts/const-for.rs: pass -> [missing] (J4)
[ui] tests/ui/traits/next-solver/rpit-in-trait-malformed-bound-globally-156100.rs: [missing] -> pass (J4)
[ui] tests/ui-fulldeps/rustc_public/check_abi_cast.rs: [missing] -> ignore (only executed when the target is x86_64-unknown-linux-gnu) (J5)

Additionally, 595 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 92801ede88f6c10e34df6976a4cfde40142585f2 --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

test-x86_64-msvc-ext3: 1h 14m -> 2h (+61.5%)
test-x86_64-gnu-distcheck: 1h 32m -> 2h 24m (+56.7%)
dist-riscv64-linux-musl: 59m 21s -> 1h 31m (+55.0%)
test-various: 1h 29m -> 2h 18m (+54.9%)
dist-ohos-x86_64: 1h 23m -> 54m 23s (-34.5%)
test-x86_64-gnu-stable: 2h 42m -> 1h 49m (-32.3%)
dist-sparcv9-solaris: 1h 45m -> 1h 13m (-30.0%)
dist-i586-gnu-i586-i686-musl: 21m 42s -> 27m 46s (+28.0%)
test-aarch64-apple-macos-26-1: 1h 57m -> 2h 30m (+27.3%)
test-pr-check-1: 32m 44s -> 41m 35s (+27.0%)

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 · 2026-09-16T18:14:09Z

Finished benchmarking commit (92801ed): comparison URL.

Overall result: ❌ regressions - 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)	0.5%	[0.5%, 0.5%]	1
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[0.5%, 0.5%]	1

Max RSS (memory usage)

Results (primary 0.3%, 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)	2.6%	[0.6%, 3.8%]	5
Regressions ❌ (secondary)	3.4%	[3.0%, 4.0%]	3
Improvements ✅ (primary)	-3.6%	[-5.8%, -2.2%]	3
Improvements ✅ (secondary)	-4.4%	[-4.9%, -4.0%]	6
All ❌✅ (primary)	0.3%	[-5.8%, 3.8%]	8

Cycles

Results (primary -2.6%)

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)	-2.6%	[-2.6%, -2.6%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.6%	[-2.6%, -2.6%]	1

Binary size

Results (primary 0.1%)

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

	mean	range	count
Regressions ❌ (primary)	0.1%	[0.1%, 0.8%]	12
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.1%, 0.8%]	12

Bootstrap: 494.504s -> 496.571s (0.42%)
Artifact size: 406.72 MiB -> 408.84 MiB (0.52%)

rust-bors · 2026-09-16T18:36:02Z

📌 Perf builds for each rolled up PR:

PR#	Message	Perf Build Sha
#156216	implement const Iterator for Range	`d590e758c24013648ce05cc7f5cff237acf44971` (link)
#160697	rustc: Tweak the effect of `--jobs` on frontend parallelism	`6efd7e690559249ec4ffdce2c098164f299d327a` (link)
#162748	Enable LLVM Thin LTO for LoongArch64	`91790d27e32b77d9d8f553c6e4a119e8765c740e` (link)
#162769	Yeet the `DeepRegionResolver` (earlier called `Opportunisti…	`6fd08ec252167b4dc0beaaa02a791bd5ad39e548` (link)
#162794	Simplify `ast::UseTreeKind`	`22a7d451e1d5da830e84404c99323ac7f913b3dc` (link)
#162800	Cleanups related to RefDecodable	`e15a3f8b0598500b5e8e308cc03528aaeebdd804` (link)
#162826	wasm: fix ABI for enums with integer layout and ZST fields	`1606c5f150d1438a62e88173ee4b44fe722a82ec` (link)
#159359	[rustc_public] Enhance PassMode API	`e82400817b4f43bae4011899333520a9f06194db` (link)
#162196	Offload cmake cleanups	`55279b973eb2df57f12e06a6578e2c667a47333d` (link)
#162818	Add regression test for malformed RPITIT bound ICE with the…	`9f5a85dab61b5de3ad826250d3f13e1864fdb3c2` (link)

parent commit: e15ceccfc6

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

Zalathar · 2026-09-17T01:14:24Z

@rust-timer triage 22a7d45 e15a3f8

rust-timer · 2026-09-17T01:14:27Z

Running triage with 2 benchmarks

Triage only executes the benchmarks on rollup members, that were changed significantly on the rollup.
For this rollup, these benchmarks are:

nalgebra-0.33.0-new-solver
unicode-normalization-0.1.24