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Tracking Issue for slice::array_chunks #74985

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#143289
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Tracking Issue for slice::array_chunks#74985
#143289
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A-arrayArea: `[T; N]`A-const-genericsArea: const generics (parameters and arguments)A-sliceArea: `[T]`C-tracking-issueCategory: An issue tracking the progress of sth. like the implementation of an RFCF-generic_const_exprs`#![feature(generic_const_exprs)]`Libs-TrackedLibs issues that are tracked on the team's project board.P-lowLow priorityT-libs-apiRelevant to the library API team, which will review and decide on the PR/issue.
@lcnr

Description

@lcnr
lcnr
opened on Jul 31, 2020 · edited by scottmcm
Contributor

The feature gate for the issue is #![feature(array_chunks)].

Also tracks as_(r)chunks(_mut) in #![feature(slice_as_chunks)] -- these were FCPed starting at #74985 (comment) below.

About tracking issues

Tracking issues are used to record the overall progress of implementation.
They are also uses as hubs connecting to other relevant issues, e.g., bugs or open design questions.
A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature.
Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

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lcnr
added
C-tracking-issueCategory: An issue tracking the progress of sth. like the implementation of an RFC
A-const-genericsArea: const generics (parameters and arguments)
F-const_generics`#![feature(const_generics)]`
T-libs-apiRelevant to the library API team, which will review and decide on the PR/issue.
on Jul 31, 2020
cuviper
mentioned this on Aug 1, 2020
JulianKnodt
mentioned this on Aug 1, 2020
KodrAus
added
Libs-TrackedLibs issues that are tracked on the team's project board.
A-sliceArea: `[T]`
on Aug 6, 2020
scottmcm
mentioned this on Sep 5, 2020
bors
added a commit that references this issue on Sep 12, 2020

Auto merge of rust-lang#75021 - cuviper:array_chunks_mut, r=scottmcm

8b6838b
scottmcm
mentioned this on Sep 12, 2020
tmandry
added a commit that references this issue on Sep 16, 2020

Rollup merge of rust-lang#75026 - JulianKnodt:array_windows, r=Amanieu

23a6777
JohnTitor
added a commit that references this issue on Oct 26, 2020

Rollup merge of rust-lang#76635 - scottmcm:slice-as-chunks, r=LukasKa…

13e88d6
joshlf

joshlf commented on Feb 10, 2021

@joshlf
joshlf
on Feb 10, 2021
Contributor

Is there any intention of providing the reverse versions of these functions?

194 remaining items

scottmcm

scottmcm commented on Jul 2, 2025

@scottmcm
scottmcm
on Jul 2, 2025
Member

There's a nice version of that in the "remove array_chunks" PR above too:

-        if v.len() % 2 != 0 {
+        let (chunks, []) = v.as_chunks::<2>() else {
             return Err(FromUtf16Error(()));
-        }
+        };

So if there's no tail expected -- there's a bug somewhere if it happens -- then something like

let (rgba, []) = data.as_chunks() else { unreachable!() };

might be a nice (and fuzzable!) way to communicate and catch that expectation.

(And yes, this is a fine place for this conversation because it's in context of whether there's sufficient value in the array_chunks iterator in addition to the already-stable stuff.)

fintelia

fintelia commented on Jul 2, 2025

@fintelia
fintelia
on Jul 2, 2025
Contributor

There's a case to be made that as_chuncks_exact should be added as shorthand for that. But I could also see not wanting to add all the combinations

briansmith

briansmith commented on Jul 2, 2025

@briansmith
briansmith
on Jul 2, 2025
Contributor

let (rgba, []) = data.as_chunks() else { unreachable!() };

This doesn't work well with coverage reporting, currently: #143149.

There's a case to be made that as_chuncks_exact should be added as shorthand for that.

This is what I do, having as_chunks_exact return an Option<&[[T; N]]> until the coverage stuff is fixed, so that I can use .unwrap_or_else(|| unreachable!()) instead of else { unreachable!() }.

But I could also see not wanting to add all the combinations

As well as maybe a long debate on whether it should return Option<> or panic.

Kixunil

Kixunil commented on Jul 3, 2025

@Kixunil
Kixunil
on Jul 3, 2025
Contributor

as_chunks_exact would be nice to have if it returned Result where the error type contains the length of the trailing slice (preferably as NonZeroUsize). Because Option has the concise alternative @scottmcm suggested but if one wants to return Result with the information it requires one more line of code.

jferrant
mentioned this on Jul 9, 2025
jhpratt
added a commit that references this issue on Jul 27, 2025

Rollup merge of rust-lang#143289 - scottmcm:remove-array-chunks, r=jh…

5eb49b3
illicitonion
mentioned this on Jul 28, 2025
samueltardieu
added a commit that references this issue on Jul 28, 2025

Rollup merge of rust-lang#143289 - scottmcm:remove-array-chunks, r=jh…

b7c9530
bors
added a commit that references this issue on Jul 29, 2025

Auto merge of #143289 - scottmcm:remove-array-chunks, r=jhpratt

cb6785f
bors
closed this as completedin cb6785fon Jul 29, 2025
tgross35
closed this as not plannedon Jul 29, 2025
github-actions
added a commit that references this issue on Jul 30, 2025

Auto merge of rust-lang#143289 - scottmcm:remove-array-chunks, r=jhpratt

bfe154b
github-actions
added a commit that references this issue on Aug 11, 2025

Auto merge of #143289 - scottmcm:remove-array-chunks, r=jhpratt

bbdc24a
bluisblu
mentioned this on Aug 31, 2025
immersum
mentioned this on Sep 9, 2025
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    A-arrayArea: `[T; N]`A-const-genericsArea: const generics (parameters and arguments)A-sliceArea: `[T]`C-tracking-issueCategory: An issue tracking the progress of sth. like the implementation of an RFCF-generic_const_exprs`#![feature(generic_const_exprs)]`Libs-TrackedLibs issues that are tracked on the team's project board.P-lowLow priorityT-libs-apiRelevant to the library API team, which will review and decide on the PR/issue.

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        Tracking Issue for slice::array_chunks · Issue #74985 · rust-lang/rust