In Rust 1.90.0, the target x86_64-apple-darwin will be demoted to Tier 2 with host tools. The standard library and the compiler will continue to be built and distributed, but automated tests of these components are no longer guaranteed to be run.

Background

Rust has supported macOS for a long time, with some amount of support dating back to Rust 0.1 and likely before that. During that time period, Apple has changed CPU architectures from x86 to x86_64 and now to Apple silicon, ultimately announcing the end of support for the x86_64 architecture.

Similarly, GitHub has announced that they will no longer provide free macOS x86_64 runners for public repositories. The Rust Project uses these runners to execute automated tests for the x86_64-apple-darwin target. Since the target tier policy requires that Tier 1 platforms must run tests in CI, the x86_64-apple-darwin target must be demoted to Tier 2.

What changes?

Starting with Rust 1.90.0, x86_64-apple-darwin will be Tier 2 with host tools. For users, nothing will change immediately; builds of both the standard library and the compiler will still be distributed by the Rust Project for use via rustup or alternative installation methods.

Over time, this target will likely accumulate bugs faster due to reduced testing.

Future

If the x86_64-apple-darwin target causes concrete problems, it may be demoted further. No plans for further demotion have been made yet.

For more details on the motivation of the demotion, see RFC 3841.