The Rust language development team plans to reduce the level of support for 32-bit Apple targets. Rust 1.41.0, due January 30, 2020, will be the last version of the language with full support for these targets, according to a bulletin published January 3, 2020.
Starting with Rust 1.42.0, 32-bit Apple targets will be reduced to “Tier 3” status, which means they won’t be available for download via the rustup installer and they will be ignored during automated builds. The main target affected by the team’s declaration is
i686 apple darwin, which is being demoted from Tier 1 to Tier 3. This affects use of the compiler on 32-bit Mac hardware as well as cross-compiling 32-bit MacOS binaries from another platform. Other targets to be demoted include
Apple has dropped support for running 32-bit binaries beginning with MacOS 10.15 and iOS 11, and prevented developers from cross-compiling 32-bit programs from Xcode 10. Thus these targets are no longer useful to Rust users, the Rust team said.
Rust developers can continue to use Rust 1.41.0 to build 32-bit binaries. Critical bug fixes and security patches will be provided until the next stable version is released on March 12, 2020. The Rust team will soon demote the targets on the nightly channel, though no exact date has been set.