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

iNFINITEi's answer doesn't work for me. I use Ubuntu, trying to compile some code with OpenCV static library. After linking, I got this:

'"/usr/bin/ld: /usr/local/lib/libopencv_core.a(parallel.cpp.o): undefined reference to symbol 'omp_set_dynamic@@OMP_1.0'"'

So I tried iNFINITEi's approach, then I have:

'CMake Error at /usr/local/share/cmake-3.13/Modules/FindPackageHandleStandardArgs.cmake:211 (message): No REQUIRED_VARS specified for FIND_PACKAGE_HANDLE_STANDARD_ARGS() Call Stack (most recent call first): /usr/local/share/cmake-3.13/Modules/FindOpenMP.cmake:513 (find_package_handle_standard_args) CMakeLists.txt:8 (FIND_PACKAGE)'

At last, I add "-fopenmp=libomp" to CMAKE_CXX_FLAGS, solved my problem.