.github/actions/setup-rust-toolchain/action.yml

name: Setup Rust toolchain
description: >-
  Install a Rust toolchain (and optional cross-compilation targets) using the
  rustup that ships on GitHub-hosted runners. This is a local replacement for
  dtolnay/rust-toolchain, which the apache org GitHub Actions allowlist blocks.

inputs:
  toolchain:
    description: Toolchain to install and set as the default (e.g. stable, 1.79.0).
    required: false
    default: stable
  targets:
    description: Space-separated list of additional compilation targets to add.
    required: false
    default: ""

runs:
  using: composite
  steps:
    # `shell: bash` is available on every GitHub-hosted runner.
    - shell: bash
      env:
        TOOLCHAIN: ${{ inputs.toolchain }}
        TARGETS: ${{ inputs.targets }}
      run: |
        set -eux
        rustup toolchain install "${TOOLCHAIN}" --profile minimal --no-self-update
        rustup default "${TOOLCHAIN}"
        if [ -n "${TARGETS}" ]; then
          # Unquoted on purpose: allow a space-separated list of targets.
          rustup target add ${TARGETS}
        fi