[jvdd]

AVX-512 target features and intrinsics are stable since Rust 1.89 (stdarch_x86_avx512, rust#138940, tracking issue rust#111137 closed). So the AVX512 code no longer needs the nightly_simd feature.

Changes

• Removed the nightly_simd gate from all AVX512 code: the avx512 modules in simd_*.rs, the AVX512 struct in config.rs, the runtime dispatch in lib.rs (avx512_supported, from fix: only dispatch 8 and 16-bit data to AVX512 when AVX512BW is available #84) and the AVX512 test cases.
• The crate-level #![feature(...)] attributes now apply only to 32-bit ARM (stdarch_arm_neon_intrinsics, stdarch_arm_feature_detection, arm_target_feature). Removed cfg_version, stdsimd, stdarch_x86_avx512 and avx512_target_feature; they are not necessary with an MSRV of 1.89.
• Added rust-version = "1.89" to Cargo.toml.
• README and crate docs: nightly_simd is only necessary for NEON on 32-bit ARM. NEON on aarch64 is stable since Rust 1.59 and was already not gated.
• CI:
  • Check_Stable now also checks the default features, on x86_64 and aarch64.
  • New Check_MSRV job: checks all features with the rust-version from Cargo.toml. There is no Cargo.lock, so the job uses CARGO_RESOLVER_INCOMPATIBLE_RUST_VERSIONS=fallback.

Side effect: on x86 and aarch64, nightly_simd now has no effect. Thus, the default features build on stable Rust for these targets. On 32-bit ARM, the default features still need nightly, as before (rust#111800 is still open). The nightly_simd feature stays, because dependents enable it (e.g. Polars: simd = ["argminmax/nightly_simd"]).

Checked

• Native on an i7-1185G7 (AVX512) with stable 1.95: cargo test --features half (the AVX512 implementations run)
• Intel SDE (Sapphire Rapids, and AVX512F without AVX512BW) with stable 1.95: all tests pass
• Rust 1.89 with the fallback resolver: cargo check --all-features
• macOS arm64: cargo test --features half on stable and nightly
• armv7: nightly with nightly_simd and stable without it build

[codspeed]

Merging this PR will not alter performance

✅ 168 untouched benchmarks

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_{Comparing feat/stable-avx512 (96a2f93) with main (4464d8e)}