[macOS: Switch to clang 21 for x86_64 job too, incl. image bump to macos-15-intel, and try clang 21 fixes]

Author: kinke

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

@@ -49,10 +49,19 @@ runs:
           sudo ln -sf $tool-21 /usr/bin/$tool
           $tool --version
         done
-    - name: 'macOS arm64: Install Homebrew clang 21' # see mimalloc comment in ../3-build-native/action.yml
-      if: runner.os == 'macOS' && inputs.arch == 'arm64'
+    - name: 'macOS: Install Homebrew clang and lld 21' # see mimalloc comment in ../3-build-native/action.yml
+      if: runner.os == 'macOS'
       shell: bash
-      run: brew install llvm@21
+      run: |
+        set -eux
+        brew install llvm@21 lld@21
+        # https://github.com/llvm/llvm-project/issues/155531#issuecomment-3229499205
+        if [[ '${{ inputs.arch }}' == arm64 ]]; then
+          prefix="/opt/homebrew/opt/llvm"
+        else
+          prefix="/usr/local/opt/llvm"
+        fi
+        rm -rf "$prefix/include/c++/v1"
     - name: 'Windows: Install clang v21.1.5 from GitHub'
       if: runner.os == 'Windows'
       shell: bash

.github/workflows/main.yml

@@ -14,7 +14,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  LLVM_VERSION: c922a5f9
+  LLVM_VERSION: 0b762af9
 
 jobs:
   build-native:
@@ -71,12 +71,15 @@ jobs:
             with_pgo: true
 
           - job_name: macOS x86_64
-            os: macos-13
+            os: macos-15-intel
             arch: x86_64
             # https://github.com/ldc-developers/ldc/issues/4462:
             # When using LTO, we need to explicitly export ~all symbols for plugin support via `ld64 -exported_symbol '__*'`.
             # Additionally `-w` to suppress resulting linker warnings.
             extra_cmake_flags: >-
+              -DCMAKE_OSX_SYSROOT=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
+              -DCMAKE_C_COMPILER=/usr/local/opt/llvm/bin/clang
+              -DCMAKE_CXX_COMPILER=/usr/local/opt/llvm/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
@@ -85,8 +88,9 @@ jobs:
             os: macos-15
             arch: arm64
             extra_cmake_flags: >-
-              -DCMAKE_C_COMPILER=/opt/homebrew/opt/llvm@21/bin/clang
-              -DCMAKE_CXX_COMPILER=/opt/homebrew/opt/llvm@21/bin/clang++
+              -DCMAKE_OSX_SYSROOT=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk
+              -DCMAKE_C_COMPILER=/opt/homebrew/opt/llvm/bin/clang
+              -DCMAKE_CXX_COMPILER=/opt/homebrew/opt/llvm/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