Nice, very nice... Looks like fun to me :)

looks_like_fun.c

typedef struct
{
  size_t size;
  void**  list;
} List;

int add(List** li, void* obj)
{
  List* list = *li ? *li : malloc(sizeof *list);
  if (list == NULL) {
    return 0;
  }
  *li = list;
  
  size_t old_size = *li ? *li->size : 0, new_size = old_size + 1;
  
  if ((old_size & new_size) == 0)
  {
    void **new_list = realloc(list->list, 2 * new_size * sizeof *list->list);
    if (new_list == NULL) {
      return 0;
    }
    list->list = new_list;
  }
  
  list->list[old_size] = obj;
  list->size = new_size;
}

void destroy_list(List** li)
{
  free(*li->list);
  free(*li);
  *li = NULL;
}

int main(void)
{
  List *l = NULL;
  add(&l, (int[]) { 25 });
  add(&l, (int[]) { 56 });
  printf("%d", ((int *) l->list[1])[0]);
  destroy(&l);
  return 0;
}