Move `SizeHint` and `IoHandle` to `core::io` by bushrat011899 · Pull Request #158539 · rust-lang/rust

bushrat011899 · 2026-06-29T04:25:30Z

ACP: rust-lang/libs-team#755
Tracking issue: #154046
Split From: #156527

Description

Move both of these internal IO traits to core::io. Since these are already unstable this is just a simple move with no observable changes.

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 · 2026-06-29T04:25:36Z

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clarfonthey · 2026-07-02T18:29:43Z

Appreciate the split PRs, thinking of offering up reviewing all of them since I'm not sure they benefit from multiple reviewers (and I already got two of them, which appear two of the latest in the chain).

But, will take a closer look today when I'm at my computer.

(Right now, replying to this one since it appears to be the "first" in the sequence.)

clarfonthey · 2026-07-02T19:40:24Z

LGTM minus the docs I mentioned. Some things look a bit weird since they're organised for future PRs but that's fine.

clarfonthey · 2026-07-02T19:49:09Z

r? @clarfonthey

This enforces the invariant that `size_hint` should always return `(lower_bound(), upper_bound())`.

Leaving the trait in a better state than it previously was. Co-Authored-By: Clar Fon <15850505+clarfonthey@users.noreply.github.com>

clarfonthey · 2026-07-03T01:38:18Z

@bors r+ rollup

Should be relatively safe to merge, just had wanted to wait for the tests to pass again. Going to just wait for this to be present in a rollup before dependent PRs get merged.

rust-bors · 2026-07-03T01:38:21Z

📌 Commit c2f51ae has been approved by clarfonthey

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 10. This pull request will be tested once the tree is reopened.

…its, r=clarfonthey Move `SizeHint` and `IoHandle` to `core::io` ACP: rust-lang/libs-team#755 Tracking issue: rust-lang#154046 Split From: rust-lang#156527 ## Description Move both of these internal IO traits to `core::io`. Since these are already unstable this is just a simple move with no observable changes. --- ## 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.

Rollup of 18 pull requests Successful merges: - #158692 (Add release notes for 1.96.1) - #134021 (Implement `IntoIterator` for `[&[mut]] Box<[T; N], A>`) - #152860 (Port the `without_debuginfo` test from `backtrace-rs` to the testsuite) - #155932 (MIR Call terminator: evaluate destination place before arguments) - #156777 (Add -Zautodiff_post_passes flag to limit which llvm passes to run after enzyme to make autodiff tests more robust) - #157151 (JSON target specs: remove 'x86-softfloat' compatibility alias) - #157835 (expand free alias types in the auto-trait orphan check) - #158377 (add `-Zforce-intrinsic-fallback` flag) - #158434 (delegation: refactor AST -> HIR lowering) - #158552 (make some tidy errors around python easier to understand) - #158624 (borrowck: Introduce BlameConstraint::to_obligation_cause_from_path()) - #158704 (Optimize `ArrayChunks::try_rfold` with `DoubleEndedIterator::next_chunk_back`) - #158711 (library: Comment on libtest's dicey internal soundness) - #158539 (Move `SizeHint` and `IoHandle` to `core::io`) - #158659 (refactor the normalization in `coerce_shared_info`) - #158689 (resolver: don't use `Finalize` when resolving visibilities during AST expansion) - #158698 (Update TypeVisitable implementation) - #158706 (Tweaks to MIR building scope API)

…its, r=clarfonthey Move `SizeHint` and `IoHandle` to `core::io` ACP: rust-lang/libs-team#755 Tracking issue: rust-lang#154046 Split From: rust-lang#156527 ## Description Move both of these internal IO traits to `core::io`. Since these are already unstable this is just a simple move with no observable changes. --- ## 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.

…uwer Rollup of 20 pull requests Successful merges: - #158692 (Add release notes for 1.96.1) - #134021 (Implement `IntoIterator` for `[&[mut]] Box<[T; N], A>`) - #155932 (MIR Call terminator: evaluate destination place before arguments) - #155989 (Update `transmute_copy` to ub_checks and `?Sized`) - #156777 (Add -Zautodiff_post_passes flag to limit which llvm passes to run after enzyme to make autodiff tests more robust) - #157151 (JSON target specs: remove 'x86-softfloat' compatibility alias) - #157835 (expand free alias types in the auto-trait orphan check) - #157857 (Stabilize `#[my_macro] mod foo;` (part of `proc_macro_hygiene`)) - #158377 (add `-Zforce-intrinsic-fallback` flag) - #158434 (delegation: refactor AST -> HIR lowering) - #158552 (make some tidy errors around python easier to understand) - #158624 (borrowck: Introduce BlameConstraint::to_obligation_cause_from_path()) - #158704 (Optimize `ArrayChunks::try_rfold` with `DoubleEndedIterator::next_chunk_back`) - #158711 (library: Comment on libtest's dicey internal soundness) - #158751 (rustdoc: Fix crash when trying to inline foreign item which cannot have attributes) - #158539 (Move `SizeHint` and `IoHandle` to `core::io`) - #158659 (refactor the normalization in `coerce_shared_info`) - #158689 (resolver: don't use `Finalize` when resolving visibilities during AST expansion) - #158698 (Update TypeVisitable implementation) - #158706 (Tweaks to MIR building scope API)

…its, r=clarfonthey Move `SizeHint` and `IoHandle` to `core::io` ACP: rust-lang/libs-team#755 Tracking issue: rust-lang#154046 Split From: rust-lang#156527 ## Description Move both of these internal IO traits to `core::io`. Since these are already unstable this is just a simple move with no observable changes. --- ## 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 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 29, 2026

rustbot assigned Mark-Simulacrum Jun 29, 2026

This was referenced Jun 29, 2026

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

Open

Move std::io::Seek to core::io #158540

Open

bushrat011899 added 2 commits June 29, 2026 15:07

Move std::io::IoHandle to core::io

cdac740

Move std::io::SizeHint to core::io

4746813

bushrat011899 force-pushed the core_io_internal_traits branch from 9d4811b to 4746813 Compare June 29, 2026 05:07

clarfonthey reviewed Jul 2, 2026

View reviewed changes

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

rustbot assigned clarfonthey and unassigned Mark-Simulacrum Jul 2, 2026

bushrat011899 and others added 2 commits July 3, 2026 10:08

Mark SizeHint::size_hint as a final method

5e19794

This enforces the invariant that `size_hint` should always return `(lower_bound(), upper_bound())`.

Add documentation to SizeHint

c2f51ae

Leaving the trait in a better state than it previously was. Co-Authored-By: Clar Fon <15850505+clarfonthey@users.noreply.github.com>

bushrat011899 requested a review from clarfonthey July 3, 2026 00:12

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 3, 2026

jhpratt mentioned this pull request Jul 3, 2026

Rollup of 18 pull requests #158753

Closed

JonathanBrouwer mentioned this pull request Jul 5, 2026

Rollup of 20 pull requests #158798

Closed

JonathanBrouwer mentioned this pull request Jul 5, 2026

Rollup of 19 pull requests #158811

Open

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Move `SizeHint` and `IoHandle` to `core::io`#158539

Move `SizeHint` and `IoHandle` to `core::io`#158539
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