static l_noret undefgoto (LexState *ls, Labeldesc *gt) {
  const char *msg;
  if (eqstr(gt->name, luaS_newliteral(ls->L, "break"))) {
    msg = "break outside loop at line %d";
    msg = luaO_pushfstring(ls->L, msg, gt->line);
  }
  else {
    msg = "no visible label '%s' for <goto> at line %d";
    msg = luaO_pushfstring(ls->L, msg, getstr(gt->name), gt->line);
  }
  luaK_semerror(ls, msg);
}