Merge topic 'FindBLAS-default-OpenMP' into release-3.20

9ef82d95 FindBLAS: Fix detection of OpenMP as dependency of BLA_STATIC

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !5993

Modules/FindBLAS.cmake

@@ -619,8 +619,17 @@ if(BLA_VENDOR STREQUAL "OpenBLAS" OR BLA_VENDOR STREQUAL "All")
     endif()
     set(_threadlibs "${CMAKE_THREAD_LIBS_INIT}")
     if(BLA_STATIC)
-      find_package(OpenMP COMPONENTS C)
-      list(PREPEND _threadlibs "${OpenMP_C_LIBRARIES}")
+      set(_blas_STATIC_CMAKE_FIND_LIBRARY_SUFFIXES "${CMAKE_FIND_LIBRARY_SUFFIXES}")
+      set(CMAKE_FIND_LIBRARY_SUFFIXES "${_blas_ORIG_CMAKE_FIND_LIBRARY_SUFFIXES}")
+      if (CMAKE_C_COMPILER_LOADED)
+        find_package(OpenMP COMPONENTS C)
+        list(PREPEND _threadlibs "${OpenMP_C_LIBRARIES}")
+      elseif(CMAKE_CXX_COMPILER_LOADED)
+        find_package(OpenMP COMPONENTS CXX)
+        list(PREPEND _threadlibs "${OpenMP_CXX_LIBRARIES}")
+      endif()
+      set(CMAKE_FIND_LIBRARY_SUFFIXES "${_blas_STATIC_CMAKE_FIND_LIBRARY_SUFFIXES}")
+      unset(_blas_STATIC_CMAKE_FIND_LIBRARY_SUFFIXES)
     endif()
     check_blas_libraries(
       BLAS_LIBRARIES