Fix OpenMP for MacOS

Author: howetuft

.github/workflows/wheel-builder.yml

@@ -207,8 +207,9 @@ jobs:
             # actually we use recent version of llvm, to get full compatibility
             # with C++20
             brew install llvm@20
-
             LLVM_PREFIX=$(brew --prefix llvm@20)
+            echo "LDFLAGS=-L${LLVM_PREFIX}/lib:$LDFLAGS" >> $GITHUB_ENV
+            echo "CPPFLAGS=-I${LLVM_PREFIX}/include" >> $GITHUB_ENV
             echo "PATH=$LLVM_PREFIX/bin:$PATH" >> $GITHUB_ENV
             echo "CC=clang" >> $GITHUB_ENV
             echo "CXX=clang++" >> $GITHUB_ENV
@@ -217,13 +218,16 @@ 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=$(brew --prefix lld@20)
+            echo "LDFLAGS=-L${LLD_PREFIX}/lib:$LDFLAGS" >> $GITHUB_ENV
+            echo "CPPFLAGS=-I${LLD_PREFIX}/include" >> $GITHUB_ENV
 
             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" >> $GITHUB_ENV
+            echo "LDFLAGS=-L${OMP_PREFIX}/lib:$LDFLAGS" >> $GITHUB_ENV
+            echo "CPPFLAGS=-I${OMP_PREFIX}/include" >> $GITHUB_ENV
 
 
       # TODO: The following block is an ugly hack but, at the moment (2025-02-25),