Setup mold linker (#6)

Sets up the [mold](https://github.com/rui314/mold) linker, defaulting to
v2.31.0 (latest at time of writing).

Author: akrantz01

.github/workflows/test.yml

@@ -13,7 +13,7 @@ permissions:
   contents: read
 
 jobs:
-  test:
+  registry:
     name: Rust ${{ matrix.rust }} using ${{ matrix.registry }}
     runs-on: ubuntu-latest
     strategy:
@@ -43,3 +43,34 @@ jobs:
       - run: cargo init . --bin --name ci
       - run: cargo add logging --registry ${{ matrix.registry }}
       - run: cargo check
+
+  linker:
+    name: Rust ${{ matrix.rust }} with mold linker
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        rust:
+          - stable
+          - beta
+          - nightly
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set registry name
+        run: sed -i "s/REGISTRY/wafflehacks/g" .cargo/config.toml
+
+      - name: TheHackerApp/setup-rust@main
+        uses: ./
+        with:
+          ssh-private-key: ${{ secrets.SHIPYARD_SSH_KEY }}
+          token: ${{ secrets.SHIPYARD_TOKEN }}
+          toolchain: ${{ matrix.rust }}
+          with-mold: true
+
+      - run: cargo init . --bin --name ci
+      - run: cargo add rand
+      - run: cargo check
+        env:
+          CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_LINKER: clang
+          CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUSTFLAGS: -C link-args=-fuse-ld=mold

action.yml

@@ -23,6 +23,14 @@ inputs:
   components:
     description: Comma-separated list of components to be additionally installed
     required: false
+  with-mold:
+    description: Whether to install the mold linker
+    required: false
+    default: true
+  mold-version:
+    description: Version of the mold linker to install
+    required: false
+    default: "2.31.0"
 
 runs:
   using: composite
@@ -52,3 +60,16 @@ runs:
       run: |
         echo "CARGO_NET_GIT_FETCH_WITH_CLI=true" >> $GITHUB_ENV
         echo "CARGO_REGISTRY_GLOBAL_CREDENTIAL_PROVIDERS=cargo:token" >> $GITHUB_ENV
+
+    - name: Install mold linker
+      shell: bash
+      if: inputs.with-mold == 'true'
+      run: |
+        wget -qO /tmp/mold.tar.gz https://github.com/rui314/mold/releases/download/v${{ inputs.mold-version }}/mold-${{ inputs.mold-version }}-x86_64-linux.tar.gz; \
+        sudo tar -xf /tmp/mold.tar.gz -C /usr/local --strip-components 1; \
+        rm /tmp/mold.tar.gz
+
+    - name: Install clang
+      shell: bash
+      if: inputs.with-mold == 'true'
+      run: sudo apt-get install -y clang libclang-dev