bytemuck

chore: Release bytemuck version 1.25.0

chore: Release bytemuck version 1.24.0

• bump derive minimum version.

• Added a windows-only ZeroableInOption impl for "stdcall" functions.

• Adds #[repr(C)] to the union Transmute<A, B> type that's used internally for most of the transmutations.

• Makes the must_cast versions of the by-value and by-ref casts be const. The mut ref cast is unaffected for now (mut references aren't yet stable in const fn). This increases the MSRV of using that particular feature from 1.57 to 1.64.

• Fully described in https://github.com/Lokathor/bytemuck/pull/256, This makes casting slices to/from ZST elements more consistent between the crate's core module and other modules.

• Fixes potential UB where BoxBytes could attempt to free a dangling pointer if the Layout is zero sized. This type was introduced in 1.14.1, so that version and the others up to and including 1.16.1 are now yanked for safety.

• NOT SEMVER SUPPORTED: Adds the nightly_float Cargo feature. This activates the f16 and f128 nightly features, and then provides Zeroable and Pod impls for those types.

• Adds a const_zeroed feature (MSRV 1.75) which puts a zeroed fn at the crate root. This is just like the Zeroable::zeroed method, but as a const fn.

This primarily relaxes the bounds on a From impl.

Previously:

impl<T: NoUninit> From<Box<T>> for BoxBytes

Now:

impl<T: ?Sized + sealed::BoxBytesOf> From<Box<T>> for BoxBytes

All related functions and methods are similarly updated.

We believe this to be backwards compatible with all previous uses, and now BoxBytes can be converted to/from more types than before.

• The new std simd nightly features are apparently arch-specific. This adjusts the feature activation to be x86/ x86_64 only.

• Changes the name of the Nightly feature activated by the crate's nightly_stdsimd feature. This is needed as of (approximately) Nightly 2024-02-06 and later, because the Nightly feature was changed.

• docs clarifications.

• Remove the requirement for the source data type to be AnyBitPattern on pod_collect_to_vec, allowing you to pod collect vecs of char into vecs of u32, or whatever.

• This has additional impls for existing traits and cleans up some internal code, but there's no new functions so I guess it counts as just a patch release.

• This bugfix makes the crate do stuff with Arc or not based on the target_has_atomic config. Previously, some targets that have allocation but not atomics were getting errors. This raises the MSRV of the extern_crate_alloc feature to 1.60, but opt-in features are not considered to be hard locked to 1.34 like the basic build of the crate is.

• Fixes try_pod_read_unaligned bug that made it always fail unless the target type was exactly pointer sized in which case UB could happen. The CheckedBitPattern::is_valid_bit_pattern was being asked to check that a reference to the pod value was a valid bit pattern, rather than the actual bit pattern itself, and so the check could in some cases be illegally bypassed.

• Patch bumped the required bytemuck_derive version because of a regression in how it handled align(N) attributes.

• Bumped the minimum bytemuck_derive dependency version from 1.0 to 1.1. The fact that bytemuck and bytemuck_derive are separate crates at all is an unfortunate technical limit of current Rust, woe and calamity.

• fu5ha added the NoUninit, AnyBitPattern, and CheckedBitPattern traits. This allows for a more fine-grained level of detail in what casting operations are allowed for a type. Types that already implement Zeroable and Pod will have a blanket impl for these new traits. This is a "preview" of the direction that the crate will probably go in the eventual 2.0 version. We're still waiting on Project Safe Transmute for an actual 2.0 version of the crate, but until then please enjoy this preview.
• Also Fusha added better support for union types in the derive macros. I still don't know how any of the proc-macro stuff works at all, so please direct questions to her.

• try_pod_read_unaligned and pod_read_unaligned let you go from &[u8] to T:Pod without worrying about alignment.

• Experimental support for the portable_simd language extension under the nightly_portable_simd cargo feature. As the name implies, this is an experimental crate feature and it's not part of the semver contract. All it does is add the appropriate Zeroable and Pod impls.

• Why does this repo keep being hit with publishing problems? What did I do to deserve this curse, Ferris? This doesn't ever happen with tinyvec or fermium, only bytemuck.

• Soundness Fix: The wrap/peel methods for owned value conversion, added to TransparentWrapper in 1.6, can cause a double-drop if used with types that impl Drop. The fix was simply to add a ManuallyDrop layer around the value before doing the transmute_copy that is used to wrap/peel. While this fix could technically be backported to the 1.6 series, since 1.7 is semver compatible anyway the 1.6 series has simply been yanked.

• Small goof with an errant ;, so PR 69 actually got things working on SPIR-V.

cargo upload goof! ignore this one.

• DJMcNab did a fix so that the crate can build for SPIR-V PR 67

• Fix bytes_of failing on zero sized types. PR 53

• thomcc fixed up the CI and patched over a soundness hole in offset_of!. PR 38

• The entire crate is now available under the Apache-2.0 OR MIT license as well as the previous Zlib license #24.
• HeroicKatora added the try_zeroed_slice_box function #10. zeroed_slice_box is also available.
• The offset_of! macro now supports a 2-arg version. For types that impl Default, it'll just make an instance using default and then call over to the 3-arg version.
• The PodCastError type now supports Hash and Display. Also if you enable the extern_crate_std feature then it will support std::error::Error.
• We now provide a TransparentWrapper<T> impl for core::num::Wrapper<T>.
• The error type of try_from_bytes and try_from_bytes_mut when the input isn't aligned has been corrected from being AlignmentMismatch (intended for allocation casting only) to TargetAlignmentGreaterAndInputNotAligned.

• Had a bug because the CI was messed up! It wasn't soundness related, because it prevented the crate from building entirely if the extern_crate_alloc feature was used. Still, this is yanked, sorry.

• thomcc added many things:
  • A fully sound offset_of! macro #10
  • A Contiguous trait for when you've got enums with declared values all in a row #12
  • A TransparentWrapper marker trait for when you want to more clearly enable adding and removing a wrapper struct to its inner value #15
  • Now MIRI is run on CI in every single push! #16

• SimonSapin added from_bytes, from_bytes_mut, try_from_bytes, and try_from_bytes_mut (PR Link)

• Changed to the zlib license.
• Added much more proper documentation.
• Reduced the minimum Rust version to 1.34