The Rust team provides different levels of support for different targets as described below.
- Tier 3 targets are technically supported by the compiler, but we don’t check whether their code builds or passes the tests, and we don’t provide any prebuilt binaries as part of our releases.
- Tier 2 targets are guaranteed to build and we provide prebuilt binaries, but we don’t execute the test suite on those platforms: the produced binaries might not work or might have bugs.
- Tier 1 targets provide the highest support guarantee, and we run the full suite on those platforms for every change merged in the compiler. Prebuilt binaries are also available.
For these and other changes in Rust 1.49.0 stable release please check out the official release notes here.