Fix x86 build with clang-18 (#101650)

* Fix x86 build with clang-18

* Suppress Wsync-alignment

* Update x86 pipeline to use clang-18

Author: am11

eng/pipelines/common/templates/pipeline-with-resources.yml

@@ -61,7 +61,7 @@ extends:
           ROOTFS_DIR: /crossrootfs/x64
 
       linux_x86:
-        image: mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-cross-x86-net8.0
+        image: mcr.microsoft.com/dotnet-buildtools/prereqs:azurelinux-3.0-cross-x86-net9.0
         env:
           ROOTFS_DIR: /crossrootfs/x86
 

src/coreclr/CMakeLists.txt

@@ -206,6 +206,7 @@ if(CLR_CMAKE_HOST_UNIX)
   # warnings and errors to be suppressed.
   # Suppress these warnings here to avoid breaking the build.
   add_compile_options($<$<COMPILE_LANG_AND_ID:CXX,Clang,AppleClang>:-Wno-null-arithmetic>)
+  add_compile_options($<$<COMPILE_LANG_AND_ID:CXX,Clang>:-Wno-sync-alignment>)
   add_compile_options($<$<COMPILE_LANG_AND_ID:CXX,GNU>:-Wno-conversion-null>)
   add_compile_options($<$<COMPILE_LANG_AND_ID:CXX,GNU>:-Wno-pointer-arith>)