Stabilize Utf8Chunks

[dtolnay]

Pending FCP in #99543.

This PR includes the proposed modification in rust-lang/libs-team#190 as agreed in #99543 (comment).

[rustbot]

r? @joboet

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[dtolnay]

@bors try

I'd like to try crater to find out whether anything is using bstr's Utf8Chunk::incomplete (#99543 (comment)). If it is, this PR would break it by making libcore's utf8_chunks() take precedence over bstr's ByteSlice extension trait. If there is widespread breakage, we need to discuss adding incomplete before stabilizing this feature, and finding out about so many uses would help justify doing so. If there is no breakage, then it's a signal we do not need to add incomplete because nobody has real-world uses for it.

[bors]

⌛ Trying commit 47ca0ce with merge 3b6ef52...

[bors]

☀️ Try build successful - checks-actions
Build commit: 3b6ef52 (3b6ef522ec6da5b39fa0cf004b820c15884319db)

[dtolnay]

@craterbot check

[craterbot]

👌 Experiment pr-123909 created and queued.
🤖 Automatically detected try build 3b6ef52
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-123909 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🎉 Experiment pr-123909 is completed!
📊 6 regressed and 0 fixed (438478 total)
📰 Open the full report.

⚠️ If you notice any spurious failure please add them to the blacklist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[joboet]

That doesn't look too bad! As far as I can tell, janetrs is the only regression, the other ones are spurious or use it as a dependency. I opened GrayJack/janetrs#10 to make it resilient against this.

[dtolnay]

@rustbot ready

[joboet]

Looks good!
@bors r+

[dtolnay]

@bors r=joboet

[bors]

📌 Commit 61cf004 has been approved by joboet

It is now in the queue for this repository.

[bors]

⌛ Testing commit 61cf004 with merge 4d570ee...

[bors]

☀️ Test successful - checks-actions
Approved by: joboet
Pushing 4d570ee to master...

[rust-timer]

Finished benchmarking commit (4d570ee): comparison URL.

Overall result: ❌ regressions - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.5%	[0.2%, 1.1%]	11
Regressions ❌ (secondary)	0.8%	[0.3%, 1.2%]	19
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.5%	[0.2%, 1.1%]	11

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)	-	-	0
Regressions ❌ (secondary)	3.3%	[3.3%, 3.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

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)	2.2%	[2.2%, 2.2%]	1
Regressions ❌ (secondary)	2.0%	[2.0%, 2.1%]	3
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.2%	[2.2%, 2.2%]	1

Binary size

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

Bootstrap: 671.828s -> 673.336s (0.22%)
Artifact size: 315.91 MiB -> 315.94 MiB (0.01%)

[lqd]

These are all doc regressions, which seems fine for perf triage purposes imo.

[Mark-Simulacrum]

I'm not so convinced. This should be a much more minor change IMO -- it might be exposing some bad performance in rustdoc (maybe some bad behavior with inherent impls?) and could be worth digging into further. Not marking as triaged yet, will try to spend some time here this week.