expanded_location xloc = expand_location (loc);
if (xloc.file == NULL || strncmp (xloc.file, "\1", 2) == 0
|| xloc.file == '\0' || xloc.file[0] == '\xff'
|| xloc.file[0] == '\0' || xloc.file[0] == '\xff'
|| xloc.file[1] == '\xff')
return false;