Function luaF_newtbcupval

3rd/lua-5.4.3/src/lfunc.c:169–180

** Insert a variable in the list of to-be-closed variables. */

** Insert a variable in the list of to-be-closed variables.
*/
void luaF_newtbcupval (lua_State *L, StkId level) {
  lua_assert(level > L->tbclist);
  if (l_isfalse(s2v(level)))
    return;  /* false doesn't need to be closed */
  checkclosemth(L, level);  /* value must have a close method */
  while (cast_uint(level - L->tbclist) > MAXDELTA) {
    L->tbclist += MAXDELTA;  /* create a dummy node at maximum delta */
    L->tbclist->tbclist.delta = 0;
  }
  level->tbclist.delta = cast(unsigned short, level - L->tbclist);
  L->tbclist = level;
}


void luaF_unlinkupval (UpVal *uv) {