feat: implement DoubleEndedSearcher for CharArray[Ref]Searcher

[vaporoxx]

This PR implements DoubleEndedSearcher for both CharArraySearcher and CharArrayRefSearcher. I'm not sure whether this was just overlooked or if there is a reason for it, but since it behaves exactly like CharSliceSearcher, I think the implementations should be appropriate.

[rustbot]

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[scottmcm]

I'm going to flip this to libs-api, on the assumption that this implies more stuff from Pattern on stable.

r? rust-lang/libs-api

[workingjubilee]

This may be made more relevant by #100806

[dtolnay]

@rust-lang/libs-api:
@rfcbot fcp merge

This PR makes iterators from split_inclusive([char; N]) and split_inclusive(&[char; N]) usable as a DoubleEndedIterator. The searcher when a slice is used as the pattern, split_inclusive(&[char]), already has the impl for this. All 3 of these iterators perform the same behavior so it makes no sense to have DoubleEndedIterator for some but not all.

fn main() {
    let mut iter = "x86_64-unknown-none".split_inclusive(['-', '_']);
    let _ = iter.next_back();
}

Be aware that the above code already compiles without this PR, but that is a bug. #100806

[rfcbot]

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

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @m-ou-se

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.

[rfcbot]

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

[rfcbot]

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.

[dtolnay]

Thanks!

[dtolnay]

@bors r+

[bors]

📌 Commit c6ed532 has been approved by dtolnay

It is now in the queue for this repository.

[bors]

⌛ Testing commit c6ed532 with merge f6dcaee...

[bors]

☀️ Test successful - checks-actions
Approved by: dtolnay
Pushing f6dcaee to master...

[rust-timer]

Finished benchmarking commit (f6dcaee): 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

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.3%	[0.5%, 4.1%]	4
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.4%	[-0.4%, -0.4%]	1
Improvements ✅ (secondary)	-1.6%	[-1.8%, -1.5%]	2
All ❌✅ (primary)	1.8%	[-0.4%, 4.1%]	5

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.9%	[0.9%, 0.9%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.9%	[0.9%, 0.9%]	1

Binary size

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

Bootstrap: 674.246s -> 675.186s (0.14%)
Artifact size: 313.61 MiB -> 313.59 MiB (-0.01%)

[dtolnay]

Nominating for backport into 1.75.0 to put this into the same release as #100806. It would be needlessly annoying to break "...".split_inclusive([...]).rev() in one release and unbreak it in the next release, when we can just not break it.