# -fvisibility=hidden
# ---------------------
# change the default visibility of symbols

# check if the compiler supports it
check_cxx_compiler_flag( "-fvisibility=hidden" HAS_VISIBILITY_HIDDEN )
# define a set of files to be compiled with the -fvisibility=hidden flag
function( set_visibility_flag )
    if ( HAS_VISIBILITY_HIDDEN )
    set_property( SOURCE ${ARGN} APPEND PROPERTY
         COMPILE_FLAGS "-fvisibility=hidden -fvisibility-inlines-hidden" )
    endif()
endfunction( set_visibility_flag )