Merge pull request #238 from ScriptedAlchemy/codex/linux-ci-mold-linker

ci: use mold for Linux Rust builds

Author: ScriptedAlchemy

.github/actions/setup-linux-mold/action.yml

@@ -0,0 +1,25 @@
+name: Setup Linux mold linker
+description: Install mold and make it the default linker for Linux Rust builds.
+
+runs:
+  using: composite
+  steps:
+    # make-default symlinks /usr/bin/ld to mold, which works on any GCC.
+    # Passing -fuse-ld=mold via RUSTFLAGS instead would break on the
+    # ubuntu-22.04 release runners: GCC only accepts that value from
+    # GCC 12 onward. It also leaves RUSTFLAGS (and rust-cache keys)
+    # untouched.
+    - name: Install mold
+      if: runner.os == 'Linux'
+      uses: rui314/setup-mold@v1
+      with:
+        mold-version: 2.41.0
+        make-default: true
+
+    - name: Verify mold is the default linker
+      if: runner.os == 'Linux'
+      shell: bash
+      run: |
+        set -euo pipefail
+        mold --version
+        ld --version | head -n 1 | grep -i mold

.github/workflows/ci.yml

@@ -72,6 +72,8 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - uses: ./.github/actions/setup-linux-mold
+
       - uses: actions/setup-node@v4
         with:
           node-version: 22
@@ -303,6 +305,9 @@ jobs:
       - uses: dtolnay/rust-toolchain@stable
         with:
           components: clippy
+
+      - uses: ./.github/actions/setup-linux-mold
+
       - name: Cache Rust build outputs
         uses: Swatinem/rust-cache@v2
         with:
@@ -377,6 +382,8 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - uses: ./.github/actions/setup-linux-mold
+
       - name: Install ast-grep
         run: |
           npm install --global "@ast-grep/cli@${AST_GREP_VERSION}"
@@ -456,6 +463,8 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - uses: ./.github/actions/setup-linux-mold
+
       - name: Install ast-grep
         run: |
           npm install --global "@ast-grep/cli@${AST_GREP_VERSION}"

.github/workflows/release-beta.yml

@@ -64,6 +64,8 @@ jobs:
         with:
           targets: ${{ matrix.target }}
 
+      - uses: ./.github/actions/setup-linux-mold
+
       - name: Use lld-link
         if: runner.os == 'Windows'
         shell: pwsh

.github/workflows/release-plz.yml

@@ -43,6 +43,8 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - uses: ./.github/actions/setup-linux-mold
+
       - name: Cache Cargo
         uses: actions/cache@v4
         with:
@@ -83,6 +85,8 @@ jobs:
 
       - uses: dtolnay/rust-toolchain@stable
 
+      - uses: ./.github/actions/setup-linux-mold
+
       - name: Cache Cargo
         uses: actions/cache@v4
         with:

.github/workflows/release.yml

@@ -73,6 +73,26 @@ jobs:
         with:
           targets: ${{ matrix.target }}
 
+      # Inline instead of ./.github/actions/setup-linux-mold: this workflow
+      # can be dispatched with an old release_tag, and the checkout above
+      # replaces the workspace with that tag, which may predate the local
+      # action. make-default symlinks ld to mold, which works on this
+      # runner's GCC 11 (unlike -fuse-ld=mold, which needs GCC 12+).
+      - name: Install mold
+        if: runner.os == 'Linux'
+        uses: rui314/setup-mold@v1
+        with:
+          mold-version: 2.41.0
+          make-default: true
+
+      - name: Verify mold is the default linker
+        if: runner.os == 'Linux'
+        shell: bash
+        run: |
+          set -euo pipefail
+          mold --version
+          ld --version | head -n 1 | grep -i mold
+
       - name: Use lld-link
         if: runner.os == 'Windows'
         shell: pwsh