Announcing Rust 1.93.0

The various *-linux-musl targets now all ship with musl 1.2.5. This primarily affects static musl builds for x86_64, aarch64, and powerpc64le which bundled musl 1.2.3. This update comes with several fixes and improvements, and a breaking change that affects the Rust ecosystem.

For the Rust ecosystem, the primary motivation for this update is to receive major improvements to musl’s DNS resolver which shipped in 1.2.4 and received bug fixes in 1.2.5. When using musl targets for static linking, this should make portable Linux binaries that do networking more reliable, particularly in the face of large DNS records and recursive nameservers.

However, 1.2.4 also comes with a breaking change: the removal of several legacy compatibility symbols that the Rust libc crate was using. A fix for this was shipped in libc 0.2.146 in June 2023 (2.5 years ago), and we believe has sufficiently widely propagated that we’re ready to make the change in Rust targets.

See our previous announcement for more details.

Rust 1.93 adjusts the internals of the standard library to permit global allocators written in Rust to use std’s thread_local! and std::thread::current without re-entrancy concerns by using the system allocator instead.

See docs for details.

Previously, if individual parts of a section of inline assembly needed to be cfg’d, the full asm! block would need to be repeated with and without that section. In 1.93, cfg can now be applied to individual statements within the asm! block.

asm!( // or global_asm! or naked_asm!
    "nop",
    #[cfg(target_feature = "sse2")]
    "nop",
    // ...
    #[cfg(target_feature = "sse2")]
    a = const 123, // only used on sse2
);