name: Setup Rust
description: Install the Rust toolchain (+ optional targets) and restore the build cache.
inputs:
  target:
    description: Comma-separated extra target triples to install
    required: false
    default: ''
  save-cache:
    description: Whether to save the Rust cache
    required: false
    default: 'false'
  restore-cache:
    description: Whether to restore the Rust cache
    required: false
    default: 'true'
  cache-namespace:
    description: >
      Cache namespace. Workflows that compile with different profile settings
      MUST use different namespaces - cargo fingerprints every dependency by its
      profile, so sharing one would mean each workflow evicts artifacts the other
      cannot use.
    required: false
    default: release-cache
runs:
  using: composite
  steps:
    - name: Install Rust (stable)
      uses: dtolnay/rust-toolchain@4cda84d5c5c54efe2404f9d843567869ab1699d4 # stable branch @ 2026-07-16
      with:
        toolchain: stable
        targets: ${{ inputs.target }}
        components: cargo, clippy, rustc, rustfmt

    - name: Cache Rust
      if: ${{ inputs.restore-cache == 'true' }}
      uses: Swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32 # v2
      with:
        key: ${{ inputs.target }}
        save-if: ${{ inputs.save-cache }}
        shared-key: ${{ inputs.cache-namespace }}
        # Release builds are long and can fail late (signing, notarization,
        # upload). Without this the whole compile is thrown away on those runs.
        cache-on-failure: true