struct die_info *extension_die; unsigned int ref;
dwarf2_extension (struct die_info *die, struct dwarf2_cu *cu){  struct attribute *attr;  struct die_info *extension_die;  unsigned int ref;  attr = dwarf2_attr (die, DW_AT_extension, cu);  if (attr == NULL)    return NULL;  ref = dwarf2_get_ref_die_offset (attr, cu);  extension_die = follow_die_ref (ref);  if (!extension_die)    {      error ("Dwarf Error: Cannot find referent at offset %d.", ref);    }  return extension_die;}