r? @jhpratt

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Has this been approved by T-libs-api? The panic message clearly says unspecified, so adding this documentation would overrule that.

If T-libs doesn't want to guarantee this, I can change the wording to "currently panics, may not panic in the future". Or even "may panic".

#155394

ping @tbu-, CI is failing. You need to add #![feature(new_range_api_legacy)] to the doc tests or import the old range types from core::ops instead.

Thanks for the ping, @Amanieu. I somehow forgot about this PR.

Note: The current status of the PR adds a new stable guarantee that the conversion will panic for an exhausted iterator.

Nominating given the implicit stability guarantee.

@rfcbot merge libs-api

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

• @Amanieu
• @BurntSushi
• @dtolnay
• @joshtriplett
• @the8472

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!

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This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

@bors r+ rollup

📌 Commit 4ff75dc has been approved by jhpratt

It is now in the queue for this repository.

@bors r-

@bors delegate+

This pull request was unapproved.

View changes since this unapproval

✌️ @tbu-, you can now approve this pull request!

If @jhpratt told you to "r=me" after making some further change, then please make that change and post @bors r=jhpratt.

View changes since this delegation.

@bors r=jhpratt

📌 Commit 48d2671 has been approved by jhpratt

It is now in the queue for this repository.

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

  IMAGE: x86_64-gnu-miri
##[endgroup]
    Updating crates.io index
error: failed to get `simd-adler32` as a dependency of package `miniz_oxide v0.8.8`
    ... which satisfies dependency `miniz_oxide = "^0.8.5"` of package `flate2 v1.1.9`
    ... which satisfies dependency `flate2 = "^1.1.9"` of package `citool v0.1.0 (/home/runner/work/rust/rust/src/ci/citool)`

Caused by:
  failed to load source for dependency `simd-adler32`

Caused by:

@bors retry

❗ You can only retry pull requests that are approved and have a previously failed auto build.

Hint: There is currently a pending auto build on this PR. To cancel it, run @bors cancel.

☀️ Test successful - CI
Approved by: jhpratt
Duration: 3h 9m 28s
Pushing 40f92b3 to main...

Comparing a774017 (parent) -> 40f92b3 (this PR)

Test differences

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 40f92b37c4f7566de7348cec4d4c2a350da598d5 --output-dir test-dashboard

Job duration changes

1. i686-gnu-nopt-2: 2h 18m -> 1h 26m (-37.6%)
2. x86_64-msvc-ext1: 2h 11m -> 1h 23m (-36.9%)
3. x86_64-gnu-llvm-21-2: 1h 33m -> 1h (-35.0%)
4. dist-i686-mingw: 2h 1m -> 2h 37m (+30.3%)
5. x86_64-gnu-gcc: 1h 5m -> 47m 6s (-28.4%)
6. dist-arm-linux-musl: 1h 19m -> 1h 37m (+23.2%)
7. dist-i686-linux: 1h 46m -> 1h 28m (-16.6%)
8. dist-android: 24m 1s -> 27m 57s (+16.4%)
9. aarch64-apple-macos-26: 2h 25m -> 2h 45m (+14.1%)
10. dist-apple-various: 1h 46m -> 1h 59m (+11.5%)

Finished benchmarking commit (40f92b3): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Cycles

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 482.353s -> 479.892s (-0.51%)
Artifact size: 390.76 MiB -> 390.75 MiB (-0.00%)