CMake cannot find OpenMP

Question

I am trying to compile with OpenMP. My CMakeLists.txt contains the line

find_package(OpenMP REQUIRED)

and CMake errors out with

Answer 1

CMake has a FindOpenMP module even in 2.x versions. See http://www.cmake.org/cmake/help/v3.0/module/FindOpenMP.html

So I'll do this:

OPTION (USE_OpenMP "Use OpenMP" ON)
IF(USE_OpenMP)
  FIND_PACKAGE(OpenMP)
  IF(OPENMP_FOUND)
    SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${OpenMP_C_FLAGS}")
    SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${OpenMP_CXX_FLAGS}")
  ENDIF()
ENDIF()