CI: Bump llvm version

Author: yamt

.github/workflows/main.yml

@@ -9,7 +9,7 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
         # oldest and newest supported LLVM version
-        clang_version: [10.0.0, 15.0.7]
+        clang_version: [10.0.0, 15.0.0]
     steps:
     - uses: actions/checkout@v1
       with:
@@ -62,7 +62,20 @@ jobs:
         echo "CC=$CLANG_DIR/clang" >> $GITHUB_ENV
         echo "AR=$CLANG_DIR/llvm-ar" >> $GITHUB_ENV
         echo "NM=$CLANG_DIR/llvm-nm" >> $GITHUB_ENV
-      if: matrix.os == 'ubuntu-latest'
+      if: matrix.os == 'ubuntu-latest' && matrix.clang_version == '10.0.0'
+
+    # use rhel-8.4 asset as ubuntu asset is not available for this release
+    - name: Install LLVM tools (Linux)
+      shell: bash
+      run: |
+        curl -sSfL https://github.com/llvm/llvm-project/releases/download/llvmorg-${{ matrix.clang_version }}/clang+llvm-${{ matrix.clang_version }}-x86_64-linux-gnu-rhel-8.4.tar.xz | tar xJf -
+        export CLANG_DIR=`pwd`/clang+llvm-${{ matrix.clang_version }}-x86_64-linux-gnu-rhel-8.4/bin
+        echo "$CLANG_DIR" >> $GITHUB_PATH
+        echo "CLANG_DIR=$CLANG_DIR" >> $GITHUB_ENV
+        echo "CC=$CLANG_DIR/clang" >> $GITHUB_ENV
+        echo "AR=$CLANG_DIR/llvm-ar" >> $GITHUB_ENV
+        echo "NM=$CLANG_DIR/llvm-nm" >> $GITHUB_ENV
+      if: matrix.os == 'ubuntu-latest' && matrix.clang_version == '15.0.0'
 
     - name: Build libc
       shell: bash