Rust 1.99.0 has been released, introducing stable C-ABI variadic functions, a long-awaited feature for systems programmers that allows developers to define variadic functions without relying on inline assembly. This update also includes improvements such as memory layout access through raw pointers, updated guidance for Box::leak, and various standard-library stabilizations. Additionally, Cargo 1.99.0 accompanies this release with a new debug profile and enhancements for workspace dependency management. The release signifies Rust's ongoing efforts to enhance its capabilities for systems programming and maintain compatibility with existing C code

Rust 1.99.0 Ships with Stable C-Variadic Functions

Rust 1.99.0 has been released today, landing in the language's usual six-month release cycle with a feature systems programmers have wanted for years. The headline change lets you finally define C-ABI variadic functions in stable Rust, closing a gap that previously forced developers to rely on inline-assembly shims. Alongside it arrives a batch of upgrades, including raw-pointer memory layout access, a fresh Box::leak recommendation, dozens of standard-library stabilizations, a new Cargo debug profile, and RISC-V Tier 2 support powered by LLVM 23.

Rust 1.99.0 Ships with Stable C-Variadic Functions @ Linux Compatible