Add `String::replace_first` and `String::replace_last` #134316

zachs18 · 2024-12-14T21:15:39Z

Convenience methods that use match_indices and replace_range to efficiently replace a substring in a string without reallocating, if capacity (and the implementation of Vec::splice) allows.

The intra-doc link to str::replacen is a direct url-based link to str::replacen in std's docs to work around #98941. This means that when building only alloc's docs (and not std's), it will be a broken link. There is precedent for this e.g. in core::hint::spin_loop which links to std::thread::yield_now using a url-based link and thus is a dead link when only building core's docs.

ACP: rust-lang/libs-team#506

rustbot · 2024-12-14T21:15:48Z

r? @tgross35

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tgross35 · 2024-12-14T21:20:56Z

I don't think I see any libs-api feedback on the other thread, and that is from a while back anyway. Could you file an ACP for this at https://github.com/rust-lang/libs-team/issues?

tgross35 · 2024-12-14T21:44:56Z

These methods would be convenient but I feel like they should probably come with an in-place replace alternative.

zachs18 · 2024-12-15T03:00:43Z

ACP opened: rust-lang/libs-team#506

@rustbot label S-waiting-on-ACP

I added String::replace_in_place (doing str::replace in-place) as a possible alternative/addition in the ACP, but I'll hold off on adding it if/until the ACP is approved with it.

bors · 2025-01-09T19:53:23Z

☔ The latest upstream changes (presumably #135286) made this pull request unmergeable. Please resolve the merge conflicts.

alex-semenyuk · 2025-02-21T20:21:01Z

@zachs18
Thanks for your contribution
Could you please rebase

tgross35 · 2025-02-21T20:23:06Z

@zachs18 Thanks for your contribution Could you please rebase

This is still waiting on the ACP

joshtriplett · 2025-10-21T15:19:44Z

@bors r+ rollup

ACP approved, PR approved.

Might be interested in the proposed replace_in_place in the future, but these seem clearly valuable and worth adding.

bors · 2025-10-21T15:19:48Z

📌 Commit 0243f5c has been approved by joshtriplett

It is now in the queue for this repository.

joshtriplett · 2025-10-21T15:20:03Z

@bors r-

r=me when the conflicts are fixed.

library/alloc/src/string.rs

tgross35 · 2025-10-21T20:30:07Z

Please also squash when you rebase, this PR has fixup commits

Rebased and modified by zachs18. Co-authored-by: zachs18 <8355914+zachs18@users.noreply.github.com>

rustbot · 2025-10-21T21:14:19Z

This PR was rebased onto a different master 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.

tgross35 · 2025-10-22T17:59:48Z

@bors rollup

…base, r=joshtriplett Add `String::replace_first` and `String::replace_last` Rebase of rust-lang#97977 (cc `@WilliamVenner)` > Convenience methods that use `match_indices` and `replace_range` to efficiently replace a substring in a string without reallocating, if capacity (and the implementation of `Vec::splice`) allows. The intra-doc link to `str::replacen` is a direct url-based link to `str::replacen` in `std`'s docs to work around rust-lang#98941. This means that when building only `alloc`'s docs (and not `std`'s), it will be a broken link. There is precedent for this e.g. in [`core::hint::spin_loop`](https://doc.rust-lang.org/nightly/src/core/hint.rs.html#214) which links to `std::thread::yield_now` using a [url-based link](https://github.com/rust-lang/rust/blob/master/library/core/src/hint.rs#L265) and thus is a dead link when only building `core`'s docs. ACP: rust-lang/libs-team#506

Zalathar · 2025-10-23T01:04:44Z

The GCC job failed again in rollup: #148010 (comment)

@bors r-

tgross35 · 2025-10-23T05:08:10Z

@bors r=joshtriplett ,tgross35

bors · 2025-10-23T05:08:12Z

📌 Commit 8ed7fca has been approved by joshtriplett

It is now in the queue for this repository.

Rollup of 3 pull requests Successful merges: - #134316 (Add `String::replace_first` and `String::replace_last`) - #147713 (Retire ast::TyAliasWhereClauses.) - #148011 (Revert constification of `AsRef for Cow` due to inference failure ) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #134316 - zachs18:string_replace_in_place_rebase, r=joshtriplett Add `String::replace_first` and `String::replace_last` Rebase of #97977 (cc `@WilliamVenner)` > Convenience methods that use `match_indices` and `replace_range` to efficiently replace a substring in a string without reallocating, if capacity (and the implementation of `Vec::splice`) allows. The intra-doc link to `str::replacen` is a direct url-based link to `str::replacen` in `std`'s docs to work around #98941. This means that when building only `alloc`'s docs (and not `std`'s), it will be a broken link. There is precedent for this e.g. in [`core::hint::spin_loop`](https://doc.rust-lang.org/nightly/src/core/hint.rs.html#214) which links to `std::thread::yield_now` using a [url-based link](https://github.com/rust-lang/rust/blob/master/library/core/src/hint.rs#L265) and thus is a dead link when only building `core`'s docs. ACP: rust-lang/libs-team#506

Rollup of 3 pull requests Successful merges: - rust-lang/rust#134316 (Add `String::replace_first` and `String::replace_last`) - rust-lang/rust#147713 (Retire ast::TyAliasWhereClauses.) - rust-lang/rust#148011 (Revert constification of `AsRef for Cow` due to inference failure ) r? `@ghost` `@rustbot` modify labels: rollup

…base, r=joshtriplett Add `String::replace_first` and `String::replace_last` Rebase of rust-lang#97977 (cc `@WilliamVenner)` > Convenience methods that use `match_indices` and `replace_range` to efficiently replace a substring in a string without reallocating, if capacity (and the implementation of `Vec::splice`) allows. The intra-doc link to `str::replacen` is a direct url-based link to `str::replacen` in `std`'s docs to work around rust-lang#98941. This means that when building only `alloc`'s docs (and not `std`'s), it will be a broken link. There is precedent for this e.g. in [`core::hint::spin_loop`](https://doc.rust-lang.org/nightly/src/core/hint.rs.html#214) which links to `std::thread::yield_now` using a [url-based link](https://github.com/rust-lang/rust/blob/master/library/core/src/hint.rs#L265) and thus is a dead link when only building `core`'s docs. ACP: rust-lang/libs-team#506

Rollup of 3 pull requests Successful merges: - rust-lang#134316 (Add `String::replace_first` and `String::replace_last`) - rust-lang#147713 (Retire ast::TyAliasWhereClauses.) - rust-lang#148011 (Revert constification of `AsRef for Cow` due to inference failure ) r? `@ghost` `@rustbot` modify labels: rollup

…base, r=joshtriplett Add `String::replace_first` and `String::replace_last` Rebase of rust-lang#97977 (cc `@WilliamVenner)` > Convenience methods that use `match_indices` and `replace_range` to efficiently replace a substring in a string without reallocating, if capacity (and the implementation of `Vec::splice`) allows. The intra-doc link to `str::replacen` is a direct url-based link to `str::replacen` in `std`'s docs to work around rust-lang#98941. This means that when building only `alloc`'s docs (and not `std`'s), it will be a broken link. There is precedent for this e.g. in [`core::hint::spin_loop`](https://doc.rust-lang.org/nightly/src/core/hint.rs.html#214) which links to `std::thread::yield_now` using a [url-based link](https://github.com/rust-lang/rust/blob/master/library/core/src/hint.rs#L265) and thus is a dead link when only building `core`'s docs. ACP: rust-lang/libs-team#506

Rollup of 3 pull requests Successful merges: - rust-lang#134316 (Add `String::replace_first` and `String::replace_last`) - rust-lang#147713 (Retire ast::TyAliasWhereClauses.) - rust-lang#148011 (Revert constification of `AsRef for Cow` due to inference failure ) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned tgross35 Dec 14, 2024

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zachs18 mentioned this pull request Dec 15, 2024

In-place String::replace_first and String::replace_last rust-lang/libs-team#506

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programmerjake suggested changes Oct 21, 2025

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zachs18 mentioned this pull request Oct 21, 2025

Tracking Issue for string_replace_in_place #147949

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Add String::replace_first and String::replace_last

8ed7fca

Rebased and modified by zachs18. Co-authored-by: zachs18 <8355914+zachs18@users.noreply.github.com>

zachs18 force-pushed the string_replace_in_place_rebase branch from 0243f5c to 8ed7fca Compare October 21, 2025 21:14

bors 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 Oct 22, 2025

Zalathar mentioned this pull request Oct 22, 2025

Rollup of 5 pull requests #148010

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bors 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Oct 23, 2025

zachs18 force-pushed the string_replace_in_place_rebase branch from 271b10c to 8ed7fca Compare October 23, 2025 03:37

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 Oct 23, 2025

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jhpratt mentioned this pull request Oct 23, 2025

Rollup of 3 pull requests #148014

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bors merged commit 4491efb into rust-lang:master Oct 23, 2025
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github-actions bot mentioned this pull request Oct 30, 2025

Toolchain upgrade to nightly-2025-11-12 flux-rs/flux#1345

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zachs18 deleted the string_replace_in_place_rebase branch November 10, 2025 17:49

Add String::replace_first and String::replace_last #134316

Add String::replace_first and String::replace_last #134316

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Add `String::replace_first` and `String::replace_last` #134316

Add `String::replace_first` and `String::replace_last` #134316

zachs18 commented Dec 14, 2024 •

edited by Dylan-DPC

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