Rust 1.87 also brings more safety to architecture intrinsics. Most std::arch intrinsics that are unsafe due to requiring target features to be enabled now are callable in safe code that has those features enabled, the Rust team said. The team provided an example of a toy program that implements summing an array using manual intrinsics that now can use safe code for the core loop.
Also in Rust 1.87, inline assembly (asm!) now can jump to labeled blocks within Rust code. This enables low-level programming such as implementing optimized control flow in operating system kernels or more efficient interaction with hardware.
Rust 1.87 also stabilizes specifying the specific captured generic types and lifetimes in trait definitions using impl Trait return types, thus allowing the use of this feature in trait definitions. This feature expands on the stabilization of non-trait functions in Rust 1.82, from October 2024.
