void my_coll_agg_error(Item** args, uint count, const char *fname,
                       int item_sep)
{
  if (count == 2)
    my_coll_agg_error(args[0]->collation, args[item_sep]->collation, fname);
  else if (count == 3)
    my_coll_agg_error(args[0]->collation, args[item_sep]->collation,
                      args[2*item_sep]->collation, fname);
  else
    my_error(ER_CANT_AGGREGATE_NCOLLATIONS,MYF(0),fname);
}
void my_coll_agg_error(Item** args, uint count, const char *fname,
                       int item_sep)
{
  if (count == 2)
    my_coll_agg_error(args[0]->collation, args[item_sep]->collation, fname);
  else if (count == 3)
    my_coll_agg_error(args[0]->collation, args[item_sep]->collation,
                      args[2*item_sep]->collation, fname);
  else
    my_error(ER_CANT_AGGREGATE_NCOLLATIONS,MYF(0),fname);
}