Document Repeat::last panic behavior by majiayu000 · Pull Request #157323 · rust-lang/rust

majiayu000 · 2026-06-02T16:16:39Z

Documents that Repeat::last always panics because Repeat is infinite.

Tests:

./x fmt --check
./x doc library/core
./x test library/core

rustbot · 2026-06-02T16:16:46Z

Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @Mark-Simulacrum (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

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Random selection from LawnGnome, Mark-Simulacrum, jhpratt

jhpratt · 2026-06-07T02:34:40Z

Can you do the same for count, which has identical behavior?

r? jhpratt

@rustbot author

rustbot · 2026-06-07T02:34:46Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

majiayu000 · 2026-06-07T04:44:22Z

Added the same panic documentation for Repeat::count.

Tests:

./x fmt --check

@rustbot ready

jhpratt · 2026-06-07T04:45:58Z

In the future, please disclose LLM usage.

jhpratt · 2026-06-07T04:51:24Z

@bors r+ rollup

rust-bors · 2026-06-07T04:51:26Z

📌 Commit a23630f has been approved by jhpratt

It is now in the queue for this repository.

… r=jhpratt Document Repeat::last panic behavior Fixes rust-lang#149707 Documents that `Repeat::last` always panics because `Repeat` is infinite. Tests: - `./x fmt --check` - `./x doc library/core` - `./x test library/core`

…uwer Rollup of 10 pull requests Successful merges: - #157447 (Move cross crate tests into the appropriate folder) - #145108 (Resolver: Batched Import Resolution) - #156119 (Further optimize `SliceIndex<str>` impl for `Range<usize>`) - #157289 (Add infallible primitive type lookups to template arg resolver) - #157540 (Cleanup and optimize `render_impls`) - #157543 (Reorganize `tests/ui/issues` [5/N]) - #156188 (riscv: promote d, e, and f target_features to CfgStableToggleUnstable) - #157323 (Document Repeat::last panic behavior) - #157545 (Suggest using comma to separate valid attribute list items) - #157559 (chore: Update annotate-snippets to 0.12.16)

… r=jhpratt Document Repeat::last panic behavior Fixes rust-lang#149707 Documents that `Repeat::last` always panics because `Repeat` is infinite. Tests: - `./x fmt --check` - `./x doc library/core` - `./x test library/core`

Rollup of 25 pull requests Successful merges: - #157447 (Move cross crate tests into the appropriate folder) - #145108 (Resolver: Batched Import Resolution) - #156119 (Further optimize `SliceIndex<str>` impl for `Range<usize>`) - #157224 (Manually unroll loop in `str::floor_char_boundary`) - #157289 (Add infallible primitive type lookups to template arg resolver) - #157540 (Cleanup and optimize `render_impls`) - #157444 (Couple of work product cleanups) - #157543 (Reorganize `tests/ui/issues` [5/N]) - #153513 (Syntactically reject equality predicates) - #155797 (LineWriter: cap write_vectored newline scan to avoid quadratic write_all_vectored) - #156155 (macros: report unbound metavariables directly) - #156188 (riscv: promote d, e, and f target_features to CfgStableToggleUnstable) - #156666 (Clarify meaning of ranges in pointer offset docs) - #157078 (Document equivalence of `highest_one` and `ilog2` methods on integers) - #157129 (ci: update download-artifact action to v8) - #157169 (triagebot: Update messages to direct changes to appropriate repositories) - #157323 (Document Repeat::last panic behavior) - #157370 (Clarify MaybeUninit::zeroed padding docs) - #157399 (Silence llbc's output by default to prevent rustc's linker output warning) - #157500 (Improve documentation of `align_of` and `Alignment`.) - #157545 (Suggest using comma to separate valid attribute list items) - #157559 (chore: Update annotate-snippets to 0.12.16) - #157560 (In `copy_nonoverlapping`, use `mul nuw nsw` to compute the byte size) - #157580 (Importing suggestion reported twice when reporting privacy error) - #157581 (Test fixup)

Rollup merge of #157323 - majiayu000:docs-repeat-last-panic, r=jhpratt Document Repeat::last panic behavior Fixes #149707 Documents that `Repeat::last` always panics because `Repeat` is infinite. Tests: - `./x fmt --check` - `./x doc library/core` - `./x test library/core`

Rollup of 25 pull requests Successful merges: - rust-lang/rust#157447 (Move cross crate tests into the appropriate folder) - rust-lang/rust#145108 (Resolver: Batched Import Resolution) - rust-lang/rust#156119 (Further optimize `SliceIndex<str>` impl for `Range<usize>`) - rust-lang/rust#157224 (Manually unroll loop in `str::floor_char_boundary`) - rust-lang/rust#157289 (Add infallible primitive type lookups to template arg resolver) - rust-lang/rust#157540 (Cleanup and optimize `render_impls`) - rust-lang/rust#157444 (Couple of work product cleanups) - rust-lang/rust#157543 (Reorganize `tests/ui/issues` [5/N]) - rust-lang/rust#153513 (Syntactically reject equality predicates) - rust-lang/rust#155797 (LineWriter: cap write_vectored newline scan to avoid quadratic write_all_vectored) - rust-lang/rust#156155 (macros: report unbound metavariables directly) - rust-lang/rust#156188 (riscv: promote d, e, and f target_features to CfgStableToggleUnstable) - rust-lang/rust#156666 (Clarify meaning of ranges in pointer offset docs) - rust-lang/rust#157078 (Document equivalence of `highest_one` and `ilog2` methods on integers) - rust-lang/rust#157129 (ci: update download-artifact action to v8) - rust-lang/rust#157169 (triagebot: Update messages to direct changes to appropriate repositories) - rust-lang/rust#157323 (Document Repeat::last panic behavior) - rust-lang/rust#157370 (Clarify MaybeUninit::zeroed padding docs) - rust-lang/rust#157399 (Silence llbc's output by default to prevent rustc's linker output warning) - rust-lang/rust#157500 (Improve documentation of `align_of` and `Alignment`.) - rust-lang/rust#157545 (Suggest using comma to separate valid attribute list items) - rust-lang/rust#157559 (chore: Update annotate-snippets to 0.12.16) - rust-lang/rust#157560 (In `copy_nonoverlapping`, use `mul nuw nsw` to compute the byte size) - rust-lang/rust#157580 (Importing suggestion reported twice when reporting privacy error) - rust-lang/rust#157581 (Test fixup)

Document Repeat::last panic behavior

355b501

rustbot assigned Mark-Simulacrum Jun 2, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 2, 2026

rustbot assigned jhpratt and unassigned Mark-Simulacrum Jun 7, 2026

rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 7, 2026

Document Repeat::count panic behavior

a23630f

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 7, 2026

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 7, 2026

JonathanBrouwer mentioned this pull request Jun 7, 2026

Rollup of 6 pull requests #157564

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JonathanBrouwer mentioned this pull request Jun 7, 2026

Rollup of 11 pull requests #157569

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JonathanBrouwer mentioned this pull request Jun 7, 2026

Rollup of 10 pull requests #157570

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JonathanBrouwer mentioned this pull request Jun 7, 2026

Rollup of 21 pull requests #157582

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This was referenced Jun 7, 2026

Rollup of 21 pull requests #157583

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Rollup of 25 pull requests #157586

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rust-bors Bot merged commit 1fcc354 into rust-lang:main Jun 8, 2026
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rustbot added this to the 1.98.0 milestone Jun 8, 2026

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Document Repeat::last panic behavior#157323

Document Repeat::last panic behavior#157323
rust-bors[bot] merged 2 commits into
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majiayu000:docs-repeat-last-panic

majiayu000 commented Jun 2, 2026 •

edited by rustbot

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majiayu000 commented Jun 2, 2026 •

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