Avoid overflow in IoSlice::advance_slices

[eduardosm]

Noticed in #62726 (comment).

[rustbot]

r? @Mark-Simulacrum

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[Mark-Simulacrum]

@bors r+

[bors]

📌 Commit 9386338 has been approved by Mark-Simulacrum

It is now in the queue for this repository.

[bors]

⌛ Testing commit 9386338 with merge 6971227...

[bors]

💔 Test failed - checks-actions

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

[compiler-errors]

@bors retry spurious

[bors]

⌛ Testing commit 9386338 with merge 8e30726...

[rust-log-analyzer]

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

 "NO_DEBUG_ASSERTIONS": 1,
 "NO_OVERFLOW_CHECKS": 1
}
##[endgroup]
jq: error: Top-level program not given (try ".")
jq: 1 compile error
##[error]Process completed with exit code 3.
[command]/usr/local/bin/git version
git version 2.42.0
Copying '/Users/runner/.gitconfig' to '/Users/runner/work/_temp/6874a12a-f302-47c7-b413-2c480d9e224a/.gitconfig'
Temporarily overriding HOME='/Users/runner/work/_temp/6874a12a-f302-47c7-b413-2c480d9e224a' before making global git config changes

[bors]

💔 Test failed - checks-actions

[compiler-errors]

@bors retry

[bors]

⌛ Testing commit 9386338 with merge 7bf47a4...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 7bf47a4 to master...

[bors]

☀️ Test successful - checks-actions
Approved by: Mark-Simulacrum
Pushing 7bf47a4 to master...

[rust-timer]

Finished benchmarking commit (7bf47a4): 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)	5.5%	[1.3%, 9.7%]	5
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.5%	[-2.5%, -2.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	4.2%	[-2.5%, 9.7%]	6

Cycles

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

Binary size

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)	0.0%	[0.0%, 0.0%]	3
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.1%	[-0.1%, -0.0%]	2
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.0%	[-0.1%, 0.0%]	5

Bootstrap: 631.251s -> 630.824s (-0.07%)
Artifact size: 317.22 MiB -> 317.29 MiB (0.02%)