check_c_source_compiles([=[
#include <sys/types.h>
int main(int argc, char *argv[]) {
  mode_t mode;
}
]=] HAVE_MODE_T)

add_compile_definitions(HAVE_MODE_T)

check_type_size (mode_t HAVE_MODE_T LANGUAGE CXX)

ENDIF(NOT HAVE_MODE_T)