Correct the const stabilization of last_chunk for slices

[tgross35]

<[T]>::last_chunk should have become const stable as part of #117561. Update the const stability gate to reflect this.

[rustbot]

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[tgross35]

This was included in the stabilization report at #117561 and split_last_chunk became const stable, I just didn't correctly update the const gate for last_chunk at that time.

@rustbot label +T-libs-api -T-libs
r? libs-api

[BurntSushi]

@bors r+

[bors]

📌 Commit 3488679 has been approved by BurntSushi

It is now in the queue for this repository.

[bors]

⌛ Testing commit 3488679 with merge cc8d9b6...

[bors]

☀️ Test successful - checks-actions
Approved by: BurntSushi
Pushing cc8d9b6 to master...

[rust-timer]

Finished benchmarking commit (cc8d9b6): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.4%	[1.4%, 1.4%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.2%	[-1.2%, -1.2%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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

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)	1.0%	[1.0%, 1.0%]	1
Regressions ❌ (secondary)	3.9%	[3.9%, 3.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-6.0%	[-6.7%, -5.5%]	4
All ❌✅ (primary)	1.0%	[1.0%, 1.0%]	1

Binary size

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

Bootstrap: 675.464s -> 676.002s (0.08%)
Artifact size: 315.71 MiB -> 315.77 MiB (0.02%)

[glandium]

<[T]>::last_chunk should have become const stable as part of #117561. Update the const stability gate to reflect this.

Except now the doc says it was stabilized const in 1.77, but using it as const with a version < 1.80 fails with

error: `core::slice::<impl [T]>::last_chunk` is not yet stable as a const fn

[glandium]

Opened #128619