How to set linker flags for OpenMP in CMake's try_compile function

Question

I would like to verify that the current compiler can build with openmp support. The application has do deploy across a wide variety of unix systems, some of which might hav

Answer 1

As of CMake 3.9 there are imported OpenMP targets per language. I consider this to be a much more elegant solution. Here's an example in C++:

cmake_minimum_required(VERSION 3.9)
project(solver LANGUAGES CXX)

find_package(OpenMP REQUIRED)
add_executable(solver solver.cc)
target_link_libraries(solver PRIVATE OpenMP::OpenMP_CXX)

This is more convenient since it is less typing, and this way you don't have to adjust with compile flags, libraries, etc which are error-prone. This is the direction that modern CMake is going.

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If you are working with something older than CMake 3.9 I still don't recommend the currently accepted answer. I believe setting the flags per-target is better:

add_executable(solver solver.cc)
target_link_libraries(solver PRIVATE "${OpenMP_CXX_FLAGS}")
target_compile_options(solver PRIVATE "${OpenMP_CXX_FLAGS}")

This may not work with some compilers; this is partly why CMake revamped its OpenMP support in CMake 3.9.