Fix OpenMP for MacOS

Author: howetuft

.github/workflows/wheel-builder.yml

@@ -207,7 +207,6 @@ jobs:
             # actually we use recent version of llvm, to get full compatibility
             # with C++20
             brew install llvm@20
-
             LLVM_PREFIX=$(brew --prefix llvm@20)
             echo "PATH=$LLVM_PREFIX/bin:$PATH" >> $GITHUB_ENV
             echo "CC=clang" >> $GITHUB_ENV
@@ -217,13 +216,16 @@ jobs:
             echo "LD=ld.lld" >> $GITHUB_ENV
             echo "DYLD_LIBRARY_PATH=$LLVM_PREFIX/lib:$DYLD_LIBRARY_PATH" >> $GITHUB_ENV
 
+            brew install lld@20
+            LLD_PREFIX=$(brew --prefix lld@20)
 
             brew install libomp
             OMP_PREFIX=$(brew --prefix libomp)
-            echo "LIBOMP=$OMP_PREFIX/lib/libomp.dylib" >> $GITHUB_ENV
-            echo "LDFLAGS=-L/usr/local/opt/libomp/lib:LDFLAGS" >> $GITHUB_ENV
-            echo "CPPFLAGS=-I/usr/local/opt/libomp/include" >> $GITHUB_ENV
-            #echo "LDFLAGS=-fuse-ld=ld.lld" >> $GITHUB_ENV
+            echo "LIBOMP=${OMP_PREFIX}/lib/libomp.dylib" >> $GITHUB_ENV
+            echo "OpenMP_CXX_INCLUDE_DIR=${OMP_PREFIX}/include" >> $GITHUB_ENV
+
+            echo "LDFLAGS=-L${OMP_PREFIX}/lib:-L${LLD_PREFIX}/lib:-L${LLVM_PREFIX}/lib" >> $GITHUB_ENV
+            echo "CPPFLAGS=-I${OMP_PREFIX}/include:-I${LLD_PREFIX}/include:-I${LLVM_PREFIX}/include" >> $GITHUB_ENV
 
 
       # TODO: The following block is an ugly hack but, at the moment (2025-02-25),

CMakeLists.txt

@@ -163,7 +163,6 @@ INCLUDE(CheckCompilerVersion)
 
 # Nota: please keep all 'find_package' gathered here (for maintenance reasons)
 message(STATUS "LuxCore - Add dependency targets")
-find_package(OpenMP REQUIRED)
 find_package(TBB REQUIRED)
 find_package(minizip REQUIRED)
 find_package(spdlog REQUIRED)
@@ -182,8 +181,12 @@ find_package(OpenSubdiv REQUIRED)
 find_package(nlohmann_json REQUIRED)
 find_package(robin_hood REQUIRED)
 if (WIN32 OR LINUX)
+  find_package(OpenMP REQUIRED)
   find_package(nvrtc REQUIRED)
 endif()
+if (APPLE)
+  find_package(OpenMP COMPONENTS CXX)
+endif()
 
 # Bison/Flex
 find_package(BISON REQUIRED)