Bump LDC-LLVM to v21.1.5

Author: kinke

.github/actions/1-setup/action.yml

@@ -37,30 +37,30 @@ runs:
         # Make sure to link libzstd statically
         sudo rm /usr/lib/$arch-linux-gnu/libzstd.so
 
-    - name: 'Linux: Install clang 20 from apt.llvm.org'
+    - name: 'Linux: Install clang 21 from apt.llvm.org'
       if: runner.os == 'Linux'
       shell: bash
       run: |
         set -eux
         cd ..
         curl -fL --retry 3 --max-time 30 -O https://apt.llvm.org/llvm.sh
-        sudo bash llvm.sh 20
+        sudo bash llvm.sh 21
         for tool in clang clang++ ld.lld; do
-          sudo ln -sf $tool-20 /usr/bin/$tool
+          sudo ln -sf $tool-21 /usr/bin/$tool
           $tool --version
         done
-    - name: 'macOS arm64: Install Homebrew clang 20' # see mimalloc comment in ../3-build-native/action.yml
+    - name: 'macOS arm64: Install Homebrew clang 21' # see mimalloc comment in ../3-build-native/action.yml
       if: runner.os == 'macOS' && inputs.arch == 'arm64'
       shell: bash
-      run: brew install llvm@20
-    - name: 'Windows: Install clang v20.1.3 from GitHub'
+      run: brew install llvm@21
+    - name: 'Windows: Install clang v21.1.5 from GitHub'
       if: runner.os == 'Windows'
       shell: bash
       run: |
         set -eux
         cd ..
         curl -fL --retry 3 --max-time 300 -o clang.exe \
-          https://github.com/llvm/llvm-project/releases/download/llvmorg-20.1.3/LLVM-20.1.3-win64.exe
+          https://github.com/llvm/llvm-project/releases/download/llvmorg-21.1.5/LLVM-21.1.5-win64.exe
         ./clang.exe //S # double-slash for bash
         rm clang.exe
         # C:\Program Files\LLVM\bin should already be in PATH

.github/workflows/main.yml

@@ -14,7 +14,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  LLVM_VERSION: 20.1.5
+  LLVM_VERSION: c922a5f9
 
 jobs:
   build-native:
@@ -85,8 +85,8 @@ jobs:
             os: macos-15
             arch: arm64
             extra_cmake_flags: >-
-              -DCMAKE_C_COMPILER=/opt/homebrew/opt/llvm@20/bin/clang
-              -DCMAKE_CXX_COMPILER=/opt/homebrew/opt/llvm@20/bin/clang++
+              -DCMAKE_C_COMPILER=/opt/homebrew/opt/llvm@21/bin/clang
+              -DCMAKE_CXX_COMPILER=/opt/homebrew/opt/llvm@21/bin/clang++
               -DD_COMPILER_FLAGS="-O -flto=full -defaultlib=phobos2-ldc-lto,druntime-ldc-lto -L-exported_symbol '-L__*' -L-w"
               -DEXTRA_CXXFLAGS=-flto=full
             with_pgo: true