Use add_compile_options() instead of setting CMAKE_CXX_FLAGS.
Use add_compile_options() instead of setting CMAKE_CXX_FLAGS.

Also, specify the required C++ standard via

    set(CMAKE_CXX_STANDARD 14)
    set(CMAKE_CXX_STANDARD_REQUIRED ON)
    set(CMAKE_CXX_EXTENSIONS OFF)

instead of forcing it via compiler parameters as using the above variables is
more universal.

s3rvac/ar-cpp