Fixed clang windows tests; more clang linux tests.

.github/workflows/test_clang_linux.yml

@@ -17,21 +17,34 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        clang_version: [13, 15]
+        clang_version: [13, 15, 18]
         cpp_version: [c++17, c++20]
         stdlib: [libc++, libstdc++] # llvm library and gcc library
         arch: [m64, m32] # 64 and 32 bit
         buildmode: [~ ,  -O3 -DNDEBUG,  -O3 -DNDEBUG -ffast-math]
-
+
+        # For simplicity, exclude 32-Bit builds for manually installed clang versions.
+        exclude:
+          - clang_version: 18
+            cpp_version: m32
+
     runs-on: ubuntu-22.04
     timeout-minutes: 10
 
     steps:
     - uses: actions/checkout@v4
 
+    - name: Install clang if required
+      # ubuntu-22.04 has at most clang 15 pre-installed. So install newer ones manually.
+      if: ${{ matrix.clang_version > 15 }}
+      uses: KyleMayes/install-llvm-action@v1.9.0
+      with:
+        version: ${{ matrix.clang_version }}
+
     - name: Install libc++ if required
       # libc++ is not installed for all clang versions by default.
-      if: ${{ matrix.stdlib == 'libc++' && matrix.arch == 'm64' }}
+      # But only do this if we are not manually installing clang.
+      if: ${{ matrix.stdlib == 'libc++' && matrix.arch == 'm64' && matrix.clang_version <= 15 }}
       run: |
         sudo apt update
         sudo apt install ${{ format('libc++-{0}-dev libc++abi-{0}-dev', matrix.clang_version) }} -y 

.github/workflows/test_clang_win.yml

@@ -29,7 +29,7 @@ jobs:
     - name: Install clang
       uses: KyleMayes/install-llvm-action@v1.9.0
       with:
-        version: matrix.clang_version
+        version: ${{ matrix.clang_version }}
     - name: Build and run tests
       working-directory: ${{env.TEST_DIR}}
       env: