w_printf
w_printf("humanize_number(\"%s\", %zu, %" PRId64 ",",
w_printf("\"%s\",", ho->ho_suffix);
w_printf("%s,", formatflags(fbuf, sizeof(fbuf), scale_flags,
w_printf("%s)", formatflags(fbuf, sizeof(fbuf), normal_flags,
w_printf("= %d,", ho->ho_retval);
w_printf("but got");
w_printf("%d/[%s]", rv, rv == -1 ? "" : buf);