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I am trying to include the omp.h library into my project, but after looking for several answers, I still don't get success. I must warn that I'm a newbie at CMake.

Using this answer, I created the following CMakeLists.txt:

cmake_minimum_required(VERSION 3.15)
project(BRKGA_FF_Best)

set(CMAKE_CXX_STANDARD 14)

include_directories(.)

if(APPLE)
  set(CMAKE_C_COMPILER clang)
  set(CMAKE_CXX_COMPILER clang++)

  if(CMAKE_C_COMPILER_ID MATCHES "Clang\$")
    set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp")
    set(OpenMP_C_LIB_NAMES "omp")
    set(OpenMP_omp_LIBRARY omp)
  endif()

  if(CMAKE_CXX_COMPILER_ID MATCHES "Clang\$")
    set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp")
    set(OpenMP_CXX_LIB_NAMES "omp")
    set(OpenMP_omp_LIBRARY omp)
  endif()
endif()

add_executable(BRKGA_FF_Best
    BRKGA.h
    main.cpp
    MTRand.h
    Population.h
    SampleDecoder.cpp
    SampleDecoder.h
    Structures.h
    Utility.cpp
    Utility.h JJSampleDecoder.h JJSampleDecoder.cpp JJmain.cpp)

target_link_libraries(BRKGA_FF_Best PRIVATE OpenMP::OpenMP_CXX)

But this generated the error fatal error: 'omp.h' file not found.

Then, I created a new file, inspired by this answer and this answer:

cmake_minimum_required(VERSION 3.15)
project(BRKGA_FF_Best)

set(CMAKE_CXX_STANDARD 14)

include_directories(.)

find_package(OpenMP REQUIRED)
set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp")
set(OpenMP_C_LIB_NAMES "omp")
set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp")
set(OpenMP_CXX_LIB_NAMES "omp")

add_executable(BRKGA_FF_Best
BRKGA.h
main.cpp
MTRand.h
Population.h
SampleDecoder.cpp
SampleDecoder.h
Structures.h
Utility.cpp
Utility.h JJSampleDecoder.h JJSampleDecoder.cpp JJmain.cpp)

target_link_libraries(BRKGA_FF_Best PRIVATE OpenMP::OpenMP_CXX)

The above file generates an error with the following message:

CMake Error at /Applications/CLion.app/Contents/bin/cmake/mac/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS OpenMP_C_LIB_NAMES)
Call Stack (most recent call first):
  /Applications/CLion.app/Contents/bin/cmake/mac/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  /Applications/CLion.app/Contents/bin/cmake/mac/share/cmake-3.15/Modules/FindOpenMP.cmake:477 (find_package_handle_standard_args)
  CMakeLists.txt:25 (find_package)

Can anyone help me with this problem? Thanks in advance.

EDIT:

As pointed by @squareskittles, I corrected the set() placing, but now another error came out. The new CMakeLists.txt is:

cmake_minimum_required(VERSION 3.15)
project(BRKGA_FF_Best)

set(CMAKE_CXX_STANDARD 14)

include_directories(.)

set(OpenMP_C_FLAGS "-Xpreprocessor -fopenmp")
set(OpenMP_C_LIB_NAMES "omp")
set(OpenMP_CXX_FLAGS "-Xpreprocessor -fopenmp")
set(OpenMP_CXX_LIB_NAMES "omp")
find_package(OpenMP REQUIRED)

add_executable(BRKGA_FF_Best
BRKGA.h
main.cpp
MTRand.h
Population.h
SampleDecoder.cpp
SampleDecoder.h
Structures.h
Utility.cpp
Utility.h JJSampleDecoder.h JJSampleDecoder.cpp JJmain.cpp)

target_link_libraries(BRKGA_FF_Best PRIVATE OpenMP::OpenMP_CXX)

And now the new error is: 

CMake Error at /Applications/CLion.app/Contents/bin/cmake/mac/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find OpenMP_C (missing: OpenMP_omp_LIBRARY)
Call Stack (most recent call first):
  /Applications/CLion.app/Contents/bin/cmake/mac/share/cmake-3.15/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  /Applications/CLion.app/Contents/bin/cmake/mac/share/cmake-3.15/Modules/FindOpenMP.cmake:477 (find_package_handle_standard_args)
  CMakeLists.txt:12 (find_package)
José Joaquim
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  • You should set the `OpenMP_` variables **before** calling `find_package()`. – Kevin Feb 27 '20 at 16:08
  • @squareskittles unfortunately, the link that you sent did not help me :( – José Joaquim Feb 27 '20 at 18:08
  • 1
    That's because you have not set *all* of the `OpenMP_` variables required for `find_package()` to work successfully. Please see the answers in the link I provided (specifically, [this](https://stackoverflow.com/a/50313962/3987854) answer). – Kevin Feb 27 '20 at 18:13
  • @squareskittles sorry, I was right looking into the accepted answer. The answer that you marked solved my problem. I had to install llvm on my mac OS. Big Thanks! – José Joaquim Feb 27 '20 at 19:14

0 Answers0