Meta: Bump CI LLVM version to 20

Author: alimpfard

.github/actions/clang-windows/action.yml

@@ -6,11 +6,11 @@ inputs:
   llvm_version:
     description: 'Version of LLVM to build and cache'
     required: false
-    default: 16.0.6
+    default: 20.1.8
   llvm_branch:
     description: 'Specific LLVM branch to build'
     required: false
-    default: "llvmorg-16.0.6"
+    default: "llvmorg-20.1.8"
 
 runs:
   using: composite

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
       fail-fast: true
       matrix:
         platform: [ubuntu-22.04]
-        cxx_compiler: [clang++-18]
+        cxx_compiler: [clang++-20]
         include:
           - platform: macos-latest
             cxx_compiler: "$(brew --prefix llvm@18)/bin/clang++"
@@ -51,7 +51,7 @@ jobs:
           sudo echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg.key] http://apt.llvm.org/${DISTRIB_CODENAME}/ llvm-toolchain-${DISTRIB_CODENAME} main" | sudo tee -a /etc/apt/sources.list.d/llvm.list
           sudo echo "deb [signed-by=/usr/share/keyrings/llvm-snapshot.gpg.key] http://apt.llvm.org/${DISTRIB_CODENAME}/ llvm-toolchain-${DISTRIB_CODENAME}-18 main" | sudo tee -a /etc/apt/sources.list.d/llvm.list
           sudo apt-get update
-          sudo apt-get install -y clang-18 libclang-18-dev
+          sudo apt-get install -y clang-20 libclang-20-dev
 
       - name: Install macOS dependencies
         if: ${{ matrix.platform == 'macos-latest' }}
@@ -107,7 +107,7 @@ jobs:
 
   selfhost-windows:
     env:
-      LLVM_VER: 18.1.6
+      LLVM_VER: 20.1.8
 
     strategy:
       fail-fast: true
@@ -125,6 +125,20 @@ jobs:
          version: 1.10.0
          dest: ${{ github.workspace }}/ninja_bin
 
+     - name: Cache Clang
+       uses: actions/cache@v3
+       id: cache-clang
+       with:
+         path: 'llvm-install-${{ env.LLVM_VER }}/'
+         key: 'libclang-${{ runner.os }}-${{ env.LLVM_VER }}'
+
+     - name: Build clang if cache miss
+       uses: ./.github/actions/clang-windows
+       if: steps.cache-clang.outputs.cache-hit != 'true'
+       with:
+         llvm_version: "${{ env.LLVM_VER }}"
+         llvm_branch: "llvmorg-${{ env.LLVM_VER }}"
+
      - name: Configure CMake
        env:
          CMAKE_PREFIX_PATH: ${{ github.workspace }}/llvm-install-${{ env.LLVM_VER }}

.github/workflows/populate-windows-clang.yml

@@ -3,7 +3,7 @@ on:
   workflow_dispatch:
 
 env:
-  LLVM_VER: 16.0.6
+  LLVM_VER: 20.1.8
 
 jobs:
   build: