Rust 1.54.0 Release Highlights: Attribute Macros and wasm32 Intrinsics Stabilization

Attributes can invoke function‑like macros

Rust 1.54 adds the ability to call function‑like macros inside attributes. Both macro_rules! macros and procedural macros invoked as macro!(...) are supported, allowing use cases such as embedding external documentation directly into Rust doc comments, e.g., using #![doc = include_str!("README.md")] .

Macros can also be nested in attributes, for example to include content generated by a build script:

#[path = concat!(env!("OUT_DIR"), "/generated.rs")]
mod generated;

Read the official release notes for more details.

wasm32 intrinsics stabilization

Many intrinsics for the wasm32 target have been stabilized, providing access to SIMD instructions in WebAssembly.

Unlike previously stabilized x86/x86_64 intrinsics, these have no safety requirements and can only be called when the appropriate target feature is enabled, reflecting WebAssembly's design for safe pre‑execution verification.

This enables some intrinsics to be exposed as fully safe functions, such as v128_bitselect , though others remain unsafe when they involve raw pointers, like v128_load .