static PointerHolder<QPDF> process_file(char const* filename,
                                        char const* password,
                                        Options& o)
{
    return do_process(&QPDF::processFile, filename, password, o,
                      strcmp(filename, "") == 0);
}
static PointerHolder<QPDF> process_file(char const* filename,
                                        char const* password,
                                        Options& o)
{
    return do_process(&QPDF::processFile, filename, password, o,
                      strcmp(filename, "") == 0);
}