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Recipes

This section contains some recipes for common tasks that you may want to perform when contributing to rustup.

Supporting a new tier 2 target with host tools

In principle, all target tuples with host tools should be recognized by rustup and have its official rustup builds. Thus, once a new target has been promoted to tier 2 with host tools, it should also be explicitly supported by rustup through the following steps:

  1. Informing rustup of the new target:

    At the moment of writing, GitHub Actions’ runners natively support Linux, Windows, and macOS. Tier 2 builds are mostly cross-compiled from Linux (except for Windows and macOS targets, which are directly compiled from the target platform), and thus we will be focusing on the Linux case below.

    You can refer to rustup#4688 for a practical example for adding a new tier 2 target via cross-builds from Linux, where you can find nearly all places where you would need to mention your new target in the rustup codebase.

    Notably, you would need to add a line in ci/actions-templates/linux-builds-template.yaml to include it in rustup’s CI, while disabling the build for this target in all scenarios. At the moment of writing, this is done by appending the YAML comment # skip-pr skip-master skip-stable at the end of the line when mentioning your target in that file.

    On the other hand, if you need to support new Windows or macOS targets, please don’t hesitate to discuss this with the team in a dedicated rustup issue.

  2. Stabilizing the target:

    When your new target reaches stable Rust, you can then enable the target in certain CI scenarios, depending on the popularity of the target. At the moment of writing, this is done by removing certain occurrences of skip-* in the aforementioned YAML comment. In most cases, you would only need to enable the target for the stable CI scenario by removing skip-stable.

    You can refer to rustup#4816 for a practical example for this step.

    Do note that when creating the PR for this step, you will need to prove that the target’s CI is indeed working by removing skip-pr in a separate commit to temporarily enable this target in this PR’s CI. Once the CI is green, you can send the link (example) to that CI run in the PR thread for verification. After that, you can safely drop the temporary commit to get the PR ready for merging.