Move `std::io::Write` to `core::io` by bushrat011899 · Pull Request #158541 · rust-lang/rust

bushrat011899 · 2026-06-29T04:46:53Z

ACP: rust-lang/libs-team#755
Tracking issue: #154046
Split From: #156527
~~Blocked On: #158537~~
~~Blocked On: #158540~~

Description

Moves std::io::Write to core::io. This is effectively a direct cut and paste, but with a large diff due to how many implementations need to be moved into alloc and core. Blocked on #158537 and #158540.

Notes

No AI tooling of any kind was used during the creation of this PR.
Please see Tracking Issue for alloc::io and core::io #154046 (comment) for a review order and broader context for this PR.

rustbot · 2026-06-29T04:46:58Z

r? @Darksonn

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bushrat011899 · 2026-06-29T04:47:03Z

@rustbot blocked

bushrat011899 · 2026-07-06T21:55:36Z

@rustbot ready
@clarfonthey This is the next PR in my chain if you're interested in reviewing this one too! I'm not assigning you just in case you don't want to take it on.

clarfonthey · 2026-07-07T01:02:04Z

r? clarfonthey

rust-bors · 2026-07-08T07:31:54Z

This pull request was unapproved.

This PR was contained in a rollup (#158941), which was unapproved.

View changes since this unapproval

bushrat011899

@rustbot author
Need to fix this sometimes-used import, unfortunately it picked up in normal CI.

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rustbot · 2026-07-08T08:06:49Z

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

Co-Authored-By: Clar Fon <15850505+clarfonthey@users.noreply.github.com>

Moves unsafe code from `alloc::io` into `alloc::vec`. A more general `try_extend_from_slice` may be useful in the future, but that requires changing how specialization is done for `SpecExtend` and that's a lot for an internal-only function.

rustbot · 2026-07-08T08:38:54Z

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.

bushrat011899 · 2026-07-08T09:16:47Z

@rustbot ready

A handful of pub(crate) functions that were previously always used in std become conditionally used once Read/Write/etc. are moved to core/alloc. I've marked those functions as #[allow(unused_imports)] to avoid changing the various callsites or adding a brittle cfg(...) to their reexport.

bushrat011899 · 2026-07-08T09:20:07Z

auto - dist-various-2 was the CI task that failed during the merge. So it might be worth a "bors try dist-various-2"?

clarfonthey · 2026-07-08T14:11:39Z

@bors try jobs=dist-various-2

Move `std::io::Write` to `core::io` try-job: dist-various-2

rust-bors · 2026-07-08T15:06:49Z

☀️ Try build successful (CI)
Build commit: f09a32d (f09a32d2764485e529832b5fd3cb8c1d59e99bd9)
Base parent: c290daa (c290daa1e5274a52e54a0f49e31bd70192abc606)

clarfonthey · 2026-07-08T15:14:50Z

@bors r+ rollup=iffy

For previous reasons of modifying a lot of I/O code and also having failed once, despite passing try now.

rust-bors · 2026-07-08T15:14:53Z

📌 Commit cb09bff has been approved by clarfonthey

It is now in the queue for this repository.

…rfonthey Move `std::io::Write` to `core::io` ACP: rust-lang/libs-team#755 Tracking issue: rust-lang#154046 Split From: rust-lang#156527 ~~Blocked On: rust-lang#158537 ~~Blocked On: rust-lang#158540 ## Description Moves `std::io::Write` to `core::io`. This is effectively a direct cut and paste, but with a large diff due to how many implementations need to be moved into `alloc` and `core`. Blocked on rust-lang#158537 and rust-lang#158540. --- ## Notes * No AI tooling of any kind was used during the creation of this PR. * Please see rust-lang#154046 (comment) for a review order and broader context for this PR.

rustbot assigned Darksonn Jun 29, 2026

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Jun 29, 2026

rustbot added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jun 29, 2026

bushrat011899 mentioned this pull request Jun 29, 2026

Tracking Issue for alloc::io and core::io #154046

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4 tasks

bushrat011899 force-pushed the core_io_write branch from 22e4295 to 802f7d5 Compare June 29, 2026 05:09

bushrat011899 mentioned this pull request Jun 29, 2026

Move std::io::Read to alloc::io #158544

Open

clarfonthey mentioned this pull request Jul 2, 2026

Add std::io::cursor::WriteThroughCursor #158537

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bushrat011899 force-pushed the core_io_write branch 2 times, most recently from ec21a69 to c806329 Compare July 3, 2026 01:49

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bushrat011899 force-pushed the core_io_write branch from c806329 to a4969f5 Compare July 6, 2026 09:35

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bushrat011899 force-pushed the core_io_write branch from a4969f5 to 9dc5fd5 Compare July 6, 2026 21:54

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rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels Jul 6, 2026

rustbot assigned clarfonthey and unassigned Darksonn Jul 7, 2026

clarfonthey reviewed Jul 7, 2026

View reviewed changes

Comment thread library/core/src/io/write.rs

clarfonthey reviewed Jul 7, 2026

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Comment thread library/core/src/io/cursor.rs Outdated

bushrat011899 requested a review from clarfonthey July 7, 2026 01:25

clarfonthey reviewed Jul 7, 2026

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Comment thread library/alloc/src/io/impls.rs Outdated

rust-bors Bot removed the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jul 8, 2026

bushrat011899 commented Jul 8, 2026

View reviewed changes

Comment thread library/std/src/io/mod.rs Outdated

bushrat011899 and others added 8 commits July 8, 2026 18:38

Move std::io::default_write_vectored to core::io

abc324c

Move std::io::cursorinternals to core::io

55585ea

Move WriteThroughCursor internals to alloc::io

66f79f1

Move std::io::Write to core::io

ec0534f

Fix documentation links to Write

4ecb0cd

Add documentation to core::io internal methods

53727e6

Co-Authored-By: Clar Fon <15850505+clarfonthey@users.noreply.github.com>

Reduce visibility of core::io::write::default_write_fmt

0e61812

Co-Authored-By: Clar Fon <15850505+clarfonthey@users.noreply.github.com>

Add Vec::try_extend_from_slice_of_bytes

cb09bff

Moves unsafe code from `alloc::io` into `alloc::vec`. A more general `try_extend_from_slice` may be useful in the future, but that requires changing how specialization is done for `SpecExtend` and that's a lot for an internal-only function.

bushrat011899 force-pushed the core_io_write branch from 65f6190 to cb09bff Compare July 8, 2026 08:38

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 Jul 8, 2026

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rust-bors Bot pushed a commit that referenced this pull request Jul 8, 2026

Auto merge of #158541 - bushrat011899:core_io_write, r=<try>

f09a32d

Move `std::io::Write` to `core::io` try-job: dist-various-2

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 Jul 8, 2026

JonathanBrouwer mentioned this pull request Jul 8, 2026

Rollup of 12 pull requests #158963

Closed

JonathanBrouwer mentioned this pull request Jul 8, 2026

Rollup of 14 pull requests #158971

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