Cache libc++ build.

.github/workflows/clang.yml

@@ -34,19 +34,28 @@ jobs:
           echo "CC=$(brew --prefix llvm)/bin/clang" >> "$GITHUB_ENV"
           echo "CXX=$(brew --prefix llvm)/bin/clang++" >> "$GITHUB_ENV"
 
-      - name: Make local build of libc++ with module enabled
+      - name: Cache libc++ build
+        id: cache-libcxx
+        uses: actions/cache@v4
+        with:
+          path: llvm-project/build
+          key: ${{ runner.os }}-libcxx
+
+      - name: Make local build of libc++ with Standard Library Module (when cache miss)
+        if: steps.cache-libcxx.outputs.cache-hit != 'true'
         run: |
           git clone https://github.com/llvm/llvm-project.git
           cd llvm-project
           mkdir build
           cmake -G Ninja -S runtimes -B build                   \
-            -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind"
+            -DLLVM_ENABLE_RUNTIMES="libcxx;libcxxabi;libunwind" \
+            -DLLVM_INCLUDE_TESTS=OFF
           ninja -C build
 
       - name: Configure
         run: |
           mkdir build
-          cmake -S . -G Ninja -B build                              \
+          cmake -S . -G Ninja -B build                                \
             -DCMAKE_CXX_STANDARD=${{ matrix.std_version }}            \
             -DLIBCXX_BUILD=${{ github.workspace }}/llvm-project/build
 

.github/workflows/msvc.yml

@@ -28,8 +28,8 @@ jobs:
       - name: Configure
         run: |
           mkdir build
-          cmake -S . -B build `
-            -G "Visual Studio 17 2022" -T v143 `
+          cmake -S . -B build                              `
+            -G "Visual Studio 17 2022" -T v143             `
             -DCMAKE_CXX_STANDARD=${{ matrix.std_version }} `
             -DVCTOOLS_INSTALL_DIR="$env:VCToolsInstallDir"