Remove `[T]::array_chunks(_mut)` #143289

scottmcm · 2025-07-01T16:36:05Z

Since libs-api is proposing as much in #74985 (comment)

try-job: dist-various-1
try-job: dist-various-2

rustbot · 2025-07-01T16:36:09Z

rustbot has assigned @jhpratt.
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

scottmcm · 2025-07-01T16:39:25Z

library/alloc/src/string.rs

-        if v.len() % 2 != 0 {
+        let (chunks, []) = v.as_chunks::<2>() else {
            return Err(FromUtf16Error(()));
-        }
+        };
        match (cfg!(target_endian = "little"), unsafe { v.align_to::<u16>() }) {
            (true, ([], v, [])) => Self::from_utf16(v),
-            _ => char::decode_utf16(v.array_chunks::<2>().copied().map(u16::from_le_bytes))
+            _ => char::decode_utf16(chunks.iter().copied().map(u16::from_le_bytes))
                .collect::<Result<_, _>>()
                .map_err(|_| FromUtf16Error(())),
        }


Hooray for let-else and slice patterns meaning this can write "the chunks with no tail", rather than needing to have an explicit % 2.

Amanieu · 2025-07-01T17:26:52Z

From #74985 (comment):

We discussed this again the @rust-lang/libs-api meeting and concluded that there is little use for an array_chunks iterator when we already have as_chunks. As such we would like to remove this unstable API.

@rfcbot merge

rfcbot · 2025-07-01T17:26:54Z

Team member @Amanieu has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

jhpratt · 2025-07-01T23:25:49Z

Let me know when CI is passing an I can take a look.

rustbot · 2025-07-02T03:25:40Z

Some changes occurred in compiler/rustc_codegen_cranelift

cc @bjorn3

scottmcm · 2025-07-02T03:46:26Z

compiler/rustc_codegen_cranelift/patches/0027-sysroot_tests-128bit-atomic-operations.patch

@@ -19,7 +19,7 @@ index 1e336bf..35e6f54 100644
 -#![cfg_attr(target_has_atomic = "128", feature(integer_atomics))]
 #![cfg_attr(test, feature(cfg_select))]
 #![feature(alloc_layout_extra)]
- #![feature(array_chunks)]
+ #![feature(array_ptr_get)]


Achievement Acquired: first CI failure from a .patch file.

scottmcm · 2025-07-02T04:49:24Z

@jhpratt This is passing CI now, if you want to take a look, but no rush since it can't land in less than 10 days anyway.

jhpratt · 2025-07-02T22:59:08Z

LGTM! r=me if/when FCP is complete.

scottmcm · 2025-07-17T06:31:24Z

Friendly reminder for the p-FCP here (#143289 (comment)), @joshtriplett @m-ou-se @BurntSushi

rfcbot · 2025-07-17T12:28:02Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rfcbot · 2025-07-27T12:33:41Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

Rollup of 7 pull requests Successful merges: - #143289 (Remove `[T]::array_chunks(_mut)`) - #143607 (Port the proc macro attributes to the new attribute parsing infrastructure) - #144471 (Remove `compiler-builtins-{no-asm,mangled-names}`) - #144495 (bump cargo_metadata) - #144523 (rustdoc: save target modifiers) - #144534 (check_static_item: explain should_check_for_sync choices) - #144535 (miri: for ABI mismatch errors, say which argument is the problem) Failed merges: - #144536 (miri subtree update) r? `@ghost` `@rustbot` modify labels: rollup

matthiaskrgr · 2025-07-27T23:15:59Z

@bors r-
#144546 (comment)

scottmcm · 2025-07-28T06:10:51Z

Trying the weird platforms that failed in the rollup...
@bors try

rust-bors · 2025-07-28T06:10:55Z

⌛ Trying commit 173926d with merge 653efc4…

To cancel the try build, run the command @bors try cancel.

Remove `[T]::array_chunks(_mut)` try-job: dist-various-1 try-job: dist-various-2

rust-bors · 2025-07-28T07:32:08Z

☀️ Try build successful (CI)
Build commit: 653efc4 (653efc42453b365d6cb04f21b38f4017de2dc3fa, parent: 733dab558992d902d6d17576de1da768094e2cf3)

scottmcm · 2025-07-28T08:33:42Z

Well the job that failed in the rollup passed, so let's give it another shot
@bors r=jhpratt rollup=maybe (failed before in platform-specific library code)

bors · 2025-07-28T08:33:45Z

📌 Commit 173926d has been approved by jhpratt

It is now in the queue for this repository.

…pratt Remove `[T]::array_chunks(_mut)` Since libs-api is proposing as much in rust-lang#74985 (comment) Closes rust-lang#74985 Closes rust-lang#76354 try-job: dist-various-1 try-job: dist-various-2

Rollup of 11 pull requests Successful merges: - #143289 (Remove `[T]::array_chunks(_mut)`) - #143883 (Add `--link-targets-dir` argument to linkchecker) - #144034 (tests: Test line number in debuginfo for diverging function calls) - #144236 (Add `core::mem::DropGuard`) - #144268 (Add method `find_ancestor_not_from_macro` and `find_ancestor_not_from_extern_macro` to supersede `find_oldest_ancestor_in_same_ctxt`) - #144303 (Consolidate staging for `rustc_private` tools) - #144539 (constify with_exposed_provenance) - #144569 (rustc-dev-guide subtree update) - #144573 (Raw Pointers are Constant PatKinds too) - #144578 (Ensure correct aligement of rustc_hir::Lifetime on platforms with lower default alignments.) - #144582 (fix `Atomic*::as_ptr` wording) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-07-29T02:27:55Z

⌛ Testing commit 173926d with merge cb6785f...

bors · 2025-07-29T05:29:03Z

☀️ Test successful - checks-actions
Approved by: jhpratt
Pushing cb6785f to master...

github-actions · 2025-07-29T05:31:34Z

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 cdccba8 (parent) -> cb6785f (this PR)

Test differences

Show 347 test diffs

Stage 1

slice::test_array_chunks_count: pass -> [missing] (J0)
slice::test_array_chunks_infer: pass -> [missing] (J0)
slice::test_array_chunks_last: pass -> [missing] (J0)
slice::test_array_chunks_mut_count: pass -> [missing] (J0)
slice::test_array_chunks_mut_infer: pass -> [missing] (J0)
slice::test_array_chunks_mut_last: pass -> [missing] (J0)
slice::test_array_chunks_mut_nth: pass -> [missing] (J0)
slice::test_array_chunks_mut_nth_back: pass -> [missing] (J0)
slice::test_array_chunks_mut_remainder: pass -> [missing] (J0)
slice::test_array_chunks_mut_zip: pass -> [missing] (J0)
slice::test_array_chunks_nth: pass -> [missing] (J0)
slice::test_array_chunks_nth_back: pass -> [missing] (J0)
slice::test_array_chunks_remainder: pass -> [missing] (J0)
slice::test_array_chunks_zip: pass -> [missing] (J0)

Additionally, 333 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, pr-check-2, test-various, x86_64-apple-1, x86_64-gnu, x86_64-gnu-aux, x86_64-gnu-llvm-19-2, x86_64-gnu-llvm-19-3, x86_64-gnu-llvm-20-2, x86_64-gnu-llvm-20-3, 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 cb6785f73df1aa3f558796a22a4ab9652cf38e26 --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-aarch64-apple: 5347.9s -> 9929.5s (85.7%)
dist-powerpc64-linux: 8091.2s -> 5215.4s (-35.5%)
x86_64-apple-2: 6410.1s -> 4707.0s (-26.6%)
dist-aarch64-linux: 8121.4s -> 5994.6s (-26.2%)
dist-x86_64-apple: 8685.0s -> 9855.1s (13.5%)
x86_64-apple-1: 8932.5s -> 8218.8s (-8.0%)
dist-apple-various: 7454.4s -> 8029.6s (7.7%)
x86_64-gnu-llvm-19-2: 5781.0s -> 6212.3s (7.5%)
x86_64-msvc-ext1: 6971.5s -> 7398.4s (6.1%)
x86_64-gnu-llvm-19-1: 3396.6s -> 3603.3s (6.1%)

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 · 2025-07-29T06:40:16Z

Finished benchmarking commit (cb6785f): 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)	-0.1%	[-0.1%, -0.1%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.5%)

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

	mean	range	count
Regressions ❌ (primary)	1.4%	[1.4%, 1.4%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.5%	[-2.3%, 1.4%]	2

Cycles

Results (secondary -3.7%)

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)	-	-	0
Improvements ✅ (secondary)	-3.7%	[-4.8%, -2.7%]	2
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 469.046s -> 467.912s (-0.24%)
Artifact size: 376.81 MiB -> 376.82 MiB (0.00%)

Remove `[T]::array_chunks(_mut)` Since libs-api is proposing as much in rust-lang#74985 (comment) Closes rust-lang#74985 Closes rust-lang#76354 try-job: dist-various-1 try-job: dist-various-2

rustbot assigned jhpratt Jul 1, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 1, 2025

scottmcm added the S-waiting-on-fcp Status: PR is in FCP and is awaiting for FCP to complete. label Jul 1, 2025

scottmcm mentioned this pull request Jul 1, 2025

Tracking Issue for slice::array_chunks #74985

Closed

7 tasks

scottmcm removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 1, 2025

scottmcm commented Jul 1, 2025

View reviewed changes

dtolnay added T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. and removed T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jul 1, 2025

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rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Jul 1, 2025

scottmcm force-pushed the remove-array-chunks branch from 9c9725c to 4814b93 Compare July 2, 2025 02:52

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scottmcm force-pushed the remove-array-chunks branch from 4814b93 to bc6d1c2 Compare July 2, 2025 03:25

scottmcm commented Jul 2, 2025

View reviewed changes

rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Jul 17, 2025

rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Jul 27, 2025

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 27, 2025

scottmcm force-pushed the remove-array-chunks branch from bc6d1c2 to 84919a4 Compare July 28, 2025 05:58

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Remove [T]::array_chunks(_mut)

173926d

scottmcm force-pushed the remove-array-chunks branch from 84919a4 to 173926d Compare July 28, 2025 06:04

rust-bors bot added a commit that referenced this pull request Jul 28, 2025

Auto merge of #143289 - scottmcm:remove-array-chunks, r=<try>

653efc4

Remove `[T]::array_chunks(_mut)` try-job: dist-various-1 try-job: dist-various-2

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jul 28, 2025

samueltardieu mentioned this pull request Jul 28, 2025

Rollup of 11 pull requests #144611

Closed

bors added the merged-by-bors This PR was explicitly merged by bors. label Jul 29, 2025

bors merged commit cb6785f into rust-lang:master Jul 29, 2025
12 checks passed

rustbot added this to the 1.90.0 milestone Jul 29, 2025

bors mentioned this pull request Jul 29, 2025

Implement split_pattern on slices #131340

Open

scottmcm deleted the remove-array-chunks branch July 29, 2025 06:00

jessefaler mentioned this pull request Jul 30, 2025

array_chunks feature was removed from Rust nightly. Fails to compile on latest nightly builds. azalea-rs/simdnbt#19

Closed

Remove [T]::array_chunks(_mut) #143289

Remove [T]::array_chunks(_mut) #143289

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Test differences

Stage 1

Job duration changes

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rust-timer commented Jul 29, 2025

Overall result: ✅ improvements - no action needed

Instruction count

Max RSS (memory usage)

Cycles

Binary size

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Remove `[T]::array_chunks(_mut)` #143289

Remove `[T]::array_chunks(_mut)` #143289

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