CI: install LLVM using apt.llvm.org/llvm.sh script on Ubuntu

Author: emillaine

.github/workflows/build.yml

@@ -19,35 +19,34 @@ jobs:
         with:
           python-version: 3.9
 
-      - name: Install Dependencies
-        shell: bash
+      - name: Download LLVM (Ubuntu)
+        if: matrix.os == 'ubuntu-latest'
         run: |
-          if [ "$RUNNER_OS" == "Linux" ]; then
-            wget --no-verbose https://github.com/llvm/llvm-project/releases/download/llvmorg-20.1.6/LLVM-20.1.6-Linux-X64.tar.xz
-            tar -xf LLVM-20.1.6-Linux-X64.tar.xz
-            echo LLVMDIR="$PWD/LLVM-20.1.6-Linux-X64" >> $GITHUB_ENV
-          fi
-          
-          if [ "$RUNNER_OS" == "macOS" ]; then
-             brew install llvm@20
-             echo LLVMDIR=$(brew --prefix llvm@20) >> $GITHUB_ENV
-          fi
-          
-          if [ "$RUNNER_OS" == "Windows" ]; then
-            curl -L "https://github.com/llvm/llvm-project/releases/download/llvmorg-20.1.6/clang+llvm-20.1.6-x86_64-pc-windows-msvc.tar.xz" --output llvm.tar.xz && 7z x llvm.tar.xz && 7z x llvm.tar
-            # The sed below converts the path to a Windows-style path
-            echo LLVMDIR="$(echo "$PWD/clang+llvm-20.1.6-x86_64-pc-windows-msvc" | sed -e 's/^\///' -e 's/\//\\/g' -e 's/^./\0:/')" >> $GITHUB_ENV
-          fi
+          wget https://apt.llvm.org/llvm.sh
+          chmod +x llvm.sh
+          sudo ./llvm.sh 20
+          echo "/usr/lib/llvm-20/bin" >> $GITHUB_PATH
+
+      - name: Download LLVM (macOS)
+        if: matrix.os == 'macos-latest'
+        run: |
+          brew install llvm@20
+          echo LLVMDIR=$(brew --prefix llvm@20) >> $GITHUB_ENV
+
+      - name: Download LLVM (Windows)
+        if: matrix.os == 'windows-latest'
+        run: |
+          curl -L "https://github.com/llvm/llvm-project/releases/download/llvmorg-20.1.6/clang+llvm-20.1.6-x86_64-pc-windows-msvc.tar.xz" --output llvm.tar.xz && 7z x llvm.tar.xz && 7z x llvm.tar
+          # The sed below converts the path to a Windows-style path
+          echo LLVMDIR="$(echo "$PWD/clang+llvm-20.1.6-x86_64-pc-windows-msvc" | sed -e 's/^\///' -e 's/\//\\/g' -e 's/^./\0:/')" >> $GITHUB_ENV
 
       - name: Create Build Environment
         run: cmake -E make_directory ${{runner.workspace}}/build
 
       - name: Configure CMake
         shell: bash
         working-directory: ${{runner.workspace}}/build
-        run: |
-          export CMAKE_BUILD_PARALLEL_LEVEL=""
-          cmake $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_PREFIX_PATH="$LLVMDIR" -DCMAKE_UNITY_BUILD=OFF
+        run: cmake $GITHUB_WORKSPACE -DCMAKE_BUILD_TYPE=$BUILD_TYPE -DCMAKE_PREFIX_PATH="$LLVMDIR" -DCMAKE_UNITY_BUILD=OFF
 
       - name: install DIA SDK # Workaround for https://github.com/llvm/llvm-project/issues/86250
         if: runner.os == 'Windows'