Guarantee that `char` has the same size and alignment as `u32` #116894

joshlf · 2023-10-18T16:15:41Z

No description provided.

rustbot · 2023-10-18T16:15:49Z

r? @m-ou-se

(rustbot has picked a reviewer for you, use r? to override)

joshlf · 2023-10-18T16:18:08Z

A change to add the same text to the Reference is here: rust-lang/reference#1401

traviscross · 2023-10-24T18:00:32Z

@rustbot labels +T-lang -T-libs +I-lang-nominated

This seems entirely a T-lang question, so I'll adjust the labels that way, but if there is some residual T-libs interest here, please relabel of course.

traviscross · 2023-10-24T18:05:21Z

r? @joshtriplett

joshtriplett · 2023-10-25T14:34:19Z

@rfcbot merge

rfcbot · 2023-10-25T14:34:24Z

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

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!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

nikomatsakis · 2023-10-25T14:38:32Z

@rfcbot reviewed

rfcbot · 2023-10-25T14:38:37Z

🔔 This is now entering its final comment period, as per the review above. 🔔

RalfJung · 2023-10-25T15:10:41Z

Note that this does *not* imply that char and u32 are ABI compatible (i.e., they are passed between functions the same way). That would probably make sense to guarantee by extending the list in the "fn" ptr type docs. (Needs a new PR since FCP already started here.)

library/core/src/primitive_docs.rs

Co-authored-by: scottmcm <[email protected]>

traviscross · 2023-10-25T19:11:07Z

@rustbot labels -I-lang-nominated

This was discussed and is now in FCP.

rfcbot · 2023-11-04T14:38:38Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

RalfJung · 2023-11-04T14:52:22Z

@bors r+ rollup

bors · 2023-11-04T14:52:25Z

📌 Commit c278bc1 has been approved by RalfJung

It is now in the queue for this repository.

…iaskrgr Rollup of 6 pull requests Successful merges: - rust-lang#110340 (Deref docs: expand and remove "smart pointer" qualifier) - rust-lang#116894 (Guarantee that `char` has the same size and alignment as `u32`) - rust-lang#117534 (clarify that the str invariant is a safety, not validity, invariant) - rust-lang#117562 (triagebot no-merges: exclude different case) - rust-lang#117570 (fallback for `construct_generic_bound_failure`) - rust-lang#117583 (Remove `'tcx` lifetime on `PlaceholderConst`) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#116894 - joshlf:patch-12, r=RalfJung Guarantee that `char` has the same size and alignment as `u32`

RalfJung · 2023-11-18T07:26:58Z

Note that this does not imply that char and u32 are ABI compatible (i.e., they are passed between functions the same way). That would probably make sense to guarantee by extending the list in the "fn" ptr type docs. (Needs a new PR since FCP already started here.)

I opened a PR for that: #118032.

guarantee that char and u32 are ABI-compatible In rust-lang#116894 we added a guarantee that `char` has the same alignment as `u32`, but there is still one axis where these types could differ: function call ABI. So let's nail that down as well: in a function signature, `char` and `u32` are completely equivalent. This is a new stable guarantee, so it will need t-lang approval.

guarantee that char and u32 are ABI-compatible In rust-lang/rust#116894 we added a guarantee that `char` has the same alignment as `u32`, but there is still one axis where these types could differ: function call ABI. So let's nail that down as well: in a function signature, `char` and `u32` are completely equivalent. This is a new stable guarantee, so it will need t-lang approval.

Pkgsrc changes: * Adjust patches and cargo checksums to new versions. * For an external LLVM, set dependency of llvm >= 16, in accordance with the upstream changes. * Mark that on NetBSD we now need >= 9.0, so 8.x is no longer supported. * On NetBSD/sparc64 10.x, we now need GCC 12 to build the embedded LLVM, which is version 17; apparently GCC 10.4 or 10.5 mis-compiles it, resulting in an illegal instruction fault during the build. Ref. rust-lang/rust#117231 Upstream changes: Version 1.75.0 (2023-12-28) ========================== - [Stabilize `async fn` and return-position `impl Trait` in traits.] (rust-lang/rust#115822) - [Allow function pointer signatures containing `&mut T` in `const` contexts.] (rust-lang/rust#116015) - [Match `usize`/`isize` exhaustively with half-open ranges.] (rust-lang/rust#116692) - [Guarantee that `char` has the same size and alignment as `u32`.] (rust-lang/rust#116894) - [Document that the null pointer has the 0 address.] (rust-lang/rust#116988) - [Allow partially moved values in `match`.] (rust-lang/rust#103208) - [Add notes about non-compliant FP behavior on 32bit x86 targets.] (rust-lang/rust#113053) - [Stabilize ratified RISC-V target features.] (rust-lang/rust#116485) Compiler -------- - [Rework negative coherence to properly consider impls that only partly overlap.] (rust-lang/rust#112875) - [Bump `COINDUCTIVE_OVERLAP_IN_COHERENCE` to deny, and warn in dependencies.] (rust-lang/rust#116493) - [Consider alias bounds when computing liveness in NLL.] (rust-lang/rust#116733) - [Add the V (vector) extension to the `riscv64-linux-android` target spec.] (rust-lang/rust#116618) - [Automatically enable cross-crate inlining for small functions] (rust-lang/rust#116505) - Add several new tier 3 targets: - [`csky-unknown-linux-gnuabiv2hf`] (rust-lang/rust#117049) - [`i586-unknown-netbsd`] (rust-lang/rust#117170) - [`mipsel-unknown-netbsd`] (rust-lang/rust#117356) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Override `Waker::clone_from` to avoid cloning `Waker`s unnecessarily.] (rust-lang/rust#96979) - [Implement `BufRead` for `VecDeque<u8>`.] (rust-lang/rust#110604) - [Implement `FusedIterator` for `DecodeUtf16` when the inner iterator does.] (rust-lang/rust#110729) - [Implement `Not, Bit{And,Or}{,Assign}` for IP addresses.] (rust-lang/rust#113747) - [Implement `Default` for `ExitCode`.] (rust-lang/rust#114589) - [Guarantee representation of None in NPO] (rust-lang/rust#115333) - [Document when atomic loads are guaranteed read-only.] (rust-lang/rust#115577) - [Broaden the consequences of recursive TLS initialization.] (rust-lang/rust#116172) - [Windows: Support sub-millisecond sleep.] (rust-lang/rust#116461) - [Fix generic bound of `str::SplitInclusive`'s `DoubleEndedIterator` impl] (rust-lang/rust#100806) - [Fix exit status / wait status on non-Unix `cfg(unix)` platforms.] (rust-lang/rust#115108) Stabilized APIs --------------- - [`Atomic*::from_ptr`] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicUsize.html#method.from_ptr) - [`FileTimes`] (https://doc.rust-lang.org/stable/std/fs/struct.FileTimes.html) - [`FileTimesExt`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTimesExt.html) - [`File::set_modified`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_modified) - [`File::set_times`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_times) - [`IpAddr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/enum.IpAddr.html#method.to_canonical) - [`Ipv6Addr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_canonical) - [`Option::as_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_slice) - [`Option::as_mut_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_mut_slice) - [`pointer::byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_add) - [`pointer::byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset) - [`pointer::byte_offset_from`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset_from) - [`pointer::byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_sub) - [`pointer::wrapping_byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_add) - [`pointer::wrapping_byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_offset) - [`pointer::wrapping_byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_sub) These APIs are now stable in const contexts: - [`Ipv6Addr::to_ipv4_mapped`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_ipv4_mapped) - [`MaybeUninit::assume_init_read`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.assume_init_read) - [`MaybeUninit::zeroed`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.zeroed) - [`mem::discriminant`] (https://doc.rust-lang.org/stable/core/mem/fn.discriminant.html) - [`mem::zeroed`] (https://doc.rust-lang.org/stable/core/mem/fn.zeroed.html) Cargo ----- - [Add new packages to `[workspace.members]` automatically.] (rust-lang/cargo#12779) - [Allow version-less `Cargo.toml` manifests.] (rust-lang/cargo#12786) - [Make browser links out of HTML file paths.] (rust-lang/cargo#12889) Rustdoc ------- - [Accept less invalid Rust in rustdoc.] (rust-lang/rust#117450) - [Document lack of object safety on affected traits.] (rust-lang/rust#113241) - [Hide `#[repr(transparent)]` if it isn't part of the public ABI.] (rust-lang/rust#115439) - [Show enum discriminant if it is a C-like variant.] (rust-lang/rust#116142) Compatibility Notes ------------------- - [FreeBSD targets now require at least version 12.] (rust-lang/rust#114521) - [Formally demote tier 2 MIPS targets to tier 3.] (rust-lang/rust#115238) - [Make misalignment a hard error in `const` contexts.] (rust-lang/rust#115524) - [Fix detecting references to packed unsized fields.] (rust-lang/rust#115583) - [Remove support for compiler plugins.] (rust-lang/rust#116412)

guarantee that char and u32 are ABI-compatible In rust-lang/rust#116894 we added a guarantee that `char` has the same alignment as `u32`, but there is still one axis where these types could differ: function call ABI. So let's nail that down as well: in a function signature, `char` and `u32` are completely equivalent. This is a new stable guarantee, so it will need t-lang approval.

Guarantee that char has the same size and alignment as u32

3fea7cc

rustbot assigned m-ou-se Oct 18, 2023

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 Oct 18, 2023

joshlf mentioned this pull request Oct 18, 2023

Guarantee char layout rust-lang/reference#1401

Merged

rustbot added I-lang-nominated Nominated for discussion during a lang team meeting. T-lang Relevant to the language team, which will review and decide on the PR/issue. and removed T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Oct 24, 2023

rustbot assigned joshtriplett and unassigned m-ou-se Oct 24, 2023

rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Oct 25, 2023

nikomatsakis approved these changes Oct 25, 2023

View reviewed changes

rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Oct 25, 2023

scottmcm reviewed Oct 25, 2023

View reviewed changes

library/core/src/primitive_docs.rs Show resolved Hide resolved

Update library/core/src/primitive_docs.rs

c278bc1

Co-authored-by: scottmcm <[email protected]>

rustbot removed the I-lang-nominated Nominated for discussion during a lang team meeting. label Oct 25, 2023

rfcbot added finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Nov 4, 2023

rfcbot added the to-announce Announce this issue on triage meeting label Nov 4, 2023

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 Nov 4, 2023

matthiaskrgr mentioned this pull request Nov 4, 2023

Rollup of 6 pull requests #117590

Merged

bors merged commit 805a56f into rust-lang:master Nov 4, 2023
11 checks passed

rustbot added this to the 1.75.0 milestone Nov 4, 2023

rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Nov 4, 2023

Unrolled build for rust-lang#116894

57a5319

Rollup merge of rust-lang#116894 - joshlf:patch-12, r=RalfJung Guarantee that `char` has the same size and alignment as `u32`

github-actions bot mentioned this pull request Nov 6, 2023

Automated pull from upstream master ferrocene/ferrocene#84

Merged

apiraino removed the to-announce Announce this issue on triage meeting label Nov 9, 2023

RalfJung mentioned this pull request Nov 18, 2023

guarantee that char and u32 are ABI-compatible #118032

Merged

zachs18 mentioned this pull request Apr 1, 2024

Should char have the same layout as u32? rust-lang/unsafe-code-guidelines#462

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Guarantee that `char` has the same size and alignment as `u32` #116894

Guarantee that `char` has the same size and alignment as `u32` #116894

joshlf commented Oct 18, 2023

rustbot commented Oct 18, 2023

joshlf commented Oct 18, 2023

traviscross commented Oct 24, 2023

traviscross commented Oct 24, 2023

joshtriplett commented Oct 25, 2023

rfcbot commented Oct 25, 2023 •

edited

Loading

nikomatsakis commented Oct 25, 2023

rfcbot commented Oct 25, 2023

RalfJung commented Oct 25, 2023 via email

traviscross commented Oct 25, 2023

rfcbot commented Nov 4, 2023

RalfJung commented Nov 4, 2023

bors commented Nov 4, 2023

RalfJung commented Nov 18, 2023

Guarantee that char has the same size and alignment as u32 #116894

Guarantee that char has the same size and alignment as u32 #116894

Conversation

joshlf commented Oct 18, 2023

rustbot commented Oct 18, 2023

joshlf commented Oct 18, 2023

traviscross commented Oct 24, 2023

traviscross commented Oct 24, 2023

joshtriplett commented Oct 25, 2023

rfcbot commented Oct 25, 2023 • edited Loading

nikomatsakis commented Oct 25, 2023

rfcbot commented Oct 25, 2023

RalfJung commented Oct 25, 2023 via email

traviscross commented Oct 25, 2023

rfcbot commented Nov 4, 2023

RalfJung commented Nov 4, 2023

bors commented Nov 4, 2023

RalfJung commented Nov 18, 2023

Guarantee that `char` has the same size and alignment as `u32` #116894

Guarantee that `char` has the same size and alignment as `u32` #116894

rfcbot commented Oct 25, 2023 •

edited

Loading