Upgrade Rust toolchain to nightly-2026-01-29 - #4651
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Pull request overview
This PR updates Kani to build against Rust nightly-2026-01-29 by adapting to recent rustc layout API changes for enums and by adding support for the simd_splat intrinsic introduced in the new SwissTable lowering path.
Changes:
- Bump pinned Rust toolchain from
nightly-2026-01-27tonightly-2026-01-29. - Update enum-layout walkers to use per-variant field offsets (
variant.offsets) forVariantsShape::Multiple. - Add
simd_splatintrinsic recognition plus CPROVER codegen support, and classify it alongside other SIMD intrinsics for analyses.
Reviewed changes
Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
| rust-toolchain.toml | Advances pinned Rust nightly toolchain version. |
| kani-compiler/src/kani_middle/transform/check_values.rs | Fixes enum field offset walking for multi-variant layouts using per-variant offsets. |
| kani-compiler/src/kani_middle/transform/check_uninit/ty_layout.rs | Fixes enum field offset walking for uninit checks using per-variant offsets. |
| kani-compiler/src/kani_middle/transform/check_uninit/ptr_uninit/uninit_visitor.rs | Treats SimdSplat as a SIMD intrinsic in uninit visitor skip logic. |
| kani-compiler/src/kani_middle/points_to/points_to_analysis.rs | Treats SimdSplat as a SIMD intrinsic in identity-aliasing classification. |
| kani-compiler/src/intrinsics.rs | Adds SimdSplat to intrinsic enum and matches "simd_splat". |
| kani-compiler/src/codegen_cprover_gotoc/codegen/intrinsic.rs | Implements codegen for SimdSplat by broadcasting scalar to all lanes. |
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feliperodri
approved these changes
Jul 17, 2026
Advance from nightly-2026-01-27 to nightly-2026-01-29. Two source changes are required (both first needed at nightly-2026-01-28); 01-29 then also passes with no further changes. - rust-lang/rust#151040 ("public-variant-layout") reworked `VariantsShape::Multiple`: its `variants` are now `VariantFields` values that expose `offsets` and `fields_by_offset_order()` directly, instead of `LayoutShape`s whose `fields: FieldsShape` had to be destructured. Update the two enum-layout walkers (check_uninit/ty_layout.rs and check_values.rs) to use the per-variant `offsets` directly (the latter previously indexed the enum's top-level offsets, which only cover the tag). - nightly-2026-01-28's HashMap/SwissTable lowers `Simd::splat` through the `simd_splat` intrinsic, which Kani did not model (unsupported construct). Add `simd_splat` support: broadcast the scalar argument to every lane of the result vector. Since `simd_splat<T, U>(value: U) -> T` has independent generic parameters, an instantiation where `U` is not `T`'s element type can reach codegen; reject it with a type-mismatch error like rustc's backends (and like Kani's `simd_extract`/`simd_insert`) instead of silently casting, and add the `simd-splat-wrong-type` expected test for it. Co-authored-by: Kiro <kiro-agent@users.noreply.github.com>
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Advance from nightly-2026-01-27 to nightly-2026-01-29. Two source changes are required (both first needed at nightly-2026-01-28); 01-29 then also passes with no further changes.
Don't expose redundant information in
rustc_public'sLayoutShaperust-lang/rust#151040 ("public-variant-layout") reworkedVariantsShape::Multiple: itsvariantsare nowVariantFieldsvalues that exposeoffsetsandfields_by_offset_order()directly, instead ofLayoutShapes whosefields: FieldsShapehad to be destructured. Update the two enum-layout walkers (check_uninit/ty_layout.rs and check_values.rs) to use the per-variantoffsetsdirectly (the latter previously indexed the enum's top-level offsets, which only cover the tag).nightly-2026-01-28's HashMap/SwissTable lowers
Simd::splatthrough thesimd_splatintrinsic, which Kani did not model (unsupported construct). Addsimd_splatsupport: broadcast the scalar argument to every lane of the result vector.By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 and MIT licenses.