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I'm trying to run this cmake file on windows 

cmake_minimum_required(VERSION 3.8)


set(CMAKE_C_COMPILER "C:/Program Files/LLVM/bin/clang")
set(CMAKE_CXX_COMPILER "C:/Program Files/LLVM/bin/clang++")
set(OPENMP_LIBRARIES "C:/Program Files/LLVM/lib")
set(OPENMP_INCLUDES "C:/Program Files/LLVM/include")


set(OpenMP_C "${CMAKE_C_COMPILER}")
set(OpenMP_C_FLAGS "-fopenmp=libomp -Wno-unused-command-line-argument")
set(OpenMP_C_LIB_NAMES "libomp" "libgomp" "libiomp5")
set(OpenMP_libomp_LIBRARY ${OpenMP_C_LIB_NAMES})
set(OpenMP_libgomp_LIBRARY ${OpenMP_C_LIB_NAMES})
set(OpenMP_libiomp5_LIBRARY ${OpenMP_C_LIB_NAMES})
set(OpenMP_CXX "${CMAKE_CXX_COMPILER}")
set(OpenMP_CXX_FLAGS "-fopenmp=libomp -Wno-unused-command-line-argument")
set(OpenMP_CXX_LIB_NAMES "libomp" "libgomp" "libiomp5")
set(OpenMP_libomp_LIBRARY ${OpenMP_CXX_LIB_NAMES})
set(OpenMP_libgomp_LIBRARY ${OpenMP_CXX_LIB_NAMES})
set(OpenMP_libiomp5_LIBRARY ${OpenMP_CXX_LIB_NAMES})


message("!!!!!!!!!!!!!!!! "  ${OpenMP_C_FLAGS} )
find_package(OpenMP REQUIRED)

With this command line parameters:

cmake -G"Visual Studio 15 2017" -T LLVM ..

It is strange that I get the fallowing error even if OpenMP_C_FLAGS is defined according to the output:

-- The C compiler identification is Clang 9.0.0
-- The CXX compiler identification is Clang 9.0.0
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe
-- Check for working CXX compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
!!!!!!!!!!!!!!!! -fopenmp=libomp -Wno-unused-command-line-argument
CMake Error at C:/Program Files/CMake/share/cmake-3.13/Modules/FindPackageHandleStandardArgs.cmake:137 (message):
  Could NOT find OpenMP_C (missing: OpenMP_C_FLAGS)
Call Stack (most recent call first):
  C:/Program Files/CMake/share/cmake-3.13/Modules/FindPackageHandleStandardArgs.cmake:378 (_FPHSA_FAILURE_MESSAGE)
  C:/Program Files/CMake/share/cmake-3.13/Modules/FindOpenMP.cmake:473 (find_package_handle_standard_args)
  CMakeLists.txt:25 (find_package)


-- Configuring incomplete, errors occurred!

If I run cmake without -T LLVM flag, then cmake FindOpenMP.cmake runs fine (uses windows compiler). clang doesn't support openmp on windows ?

user1934513
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  • Explanation of `missing: OpenMP_C_FLAGS` in CMake output: This phrase means that corresponded `FindXXX.cmake` script (`FindOpenMP.cmake` in your case) has been failed to assign the variable an appropriate value. This message does **not imply** that a user may set the variable for help the script. (Well, sometimes a user-specified variable works, but not in the given case). – Tsyvarev Feb 18 '19 at 22:22
  • There is a similar question on SO that I answered [here](https://stackoverflow.com/a/58356719/3987854). It looks like this may help in your situation. – Kevin Oct 12 '19 at 17:33

0 Answers0