MDEV-14520: Custom aggregate functions work incorrectly with WITH ROLLUP clause

Queries involving rollup need all aggregate function to have copy_or_same function where we create a copy
of item_sum items for each sum level.
Implemented copy_or_same function for the custom aggregate function class (Item_sum_sp)

mysql-test/main/custom_aggregate_functions.result

@@ -1123,3 +1123,33 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
 DROP FUNCTION f1;
+#
+# MDEV-14520: Custom aggregate functions work incorrectly with WITH ROLLUP clause
+#
+create aggregate function agg_sum(x INT) returns INT
+begin
+declare z int default 0;
+declare continue handler for not found return z;
+loop
+fetch group next row;
+set z= z+x;
+end loop;
+end|
+create table t1 (i int);
+insert into t1 values (1),(2),(2),(3);
+select i, agg_sum(i) from t1 group by i with rollup;
+i	agg_sum(i)
+1	1
+2	4
+3	3
+NULL	8
+#
+# Compare with
+select i, sum(i) from t1 group by i with rollup;
+i	sum(i)
+1	1
+2	4
+3	3
+NULL	8
+drop function agg_sum;
+drop table t1;

mysql-test/main/custom_aggregate_functions.test

@@ -939,3 +939,29 @@ SHOW CREATE TABLE t1;
 DROP TABLE t1;
 DROP FUNCTION f1;
 
+--echo #
+--echo # MDEV-14520: Custom aggregate functions work incorrectly with WITH ROLLUP clause
+--echo #
+
+--delimiter |
+create aggregate function agg_sum(x INT) returns INT
+begin
+declare z int default 0;
+declare continue handler for not found return z;
+loop
+fetch group next row;
+set z= z+x;
+end loop;
+end|
+--delimiter ;
+
+create table t1 (i int);
+insert into t1 values (1),(2),(2),(3);
+select i, agg_sum(i) from t1 group by i with rollup;
+--echo #
+--echo # Compare with
+select i, sum(i) from t1 group by i with rollup;
+
+# Cleanup
+drop function agg_sum;
+drop table t1;

sql/item.cc

@@ -2802,6 +2802,17 @@ Item_sp::Item_sp(THD *thd, Name_resolution_context *context_arg,
   memset(&sp_mem_root, 0, sizeof(sp_mem_root));
 }
 
+Item_sp::Item_sp(THD *thd, Item_sp *item):
+         context(item->context), m_name(item->m_name),
+         m_sp(item->m_sp), func_ctx(NULL), sp_result_field(NULL)
+{
+  dummy_table= (TABLE*) thd->calloc(sizeof(TABLE)+ sizeof(TABLE_SHARE) +
+                                    sizeof(Query_arena));
+  dummy_table->s= (TABLE_SHARE*) (dummy_table+1);
+  sp_query_arena= (Query_arena *) (dummy_table->s + 1);
+  memset(&sp_mem_root, 0, sizeof(sp_mem_root));
+}
+
 const char *
 Item_sp::func_name(THD *thd) const
 {

sql/item.h

@@ -4658,6 +4658,7 @@ public:
   */
   Field *sp_result_field;
   Item_sp(THD *thd, Name_resolution_context *context_arg, sp_name *name_arg);
+  Item_sp(THD *thd, Item_sp *item);
   const char *func_name(THD *thd) const;
   void cleanup();
   bool sp_check_access(THD *thd);

sql/item_sum.cc

@@ -1269,6 +1269,12 @@ Item_sum_sp::Item_sum_sp(THD *thd, Name_resolution_context *context_arg,
   m_sp= sp;
 }
 
+Item_sum_sp::Item_sum_sp(THD *thd, Item_sum_sp *item):
+             Item_sum(thd, item), Item_sp(thd, item)
+{
+  maybe_null= item->maybe_null;
+  quick_group= item->quick_group;
+}
 
 bool
 Item_sum_sp::fix_fields(THD *thd, Item **ref)
@@ -1400,6 +1406,14 @@ Item_sum_sp::func_name() const
   return Item_sp::func_name(thd);
 }
 
+Item* Item_sum_sp::copy_or_same(THD *thd)
+{
+  Item_sum_sp *copy_item= new (thd->mem_root) Item_sum_sp(thd, this);
+  copy_item->init_result_field(thd, max_length, maybe_null, 
+                               &copy_item->null_value, &copy_item->name);
+  return copy_item;
+}
+
 /***********************************************************************
 ** reset and add of sum_func
 ***********************************************************************/

sql/item_sum.h

@@ -1292,6 +1292,7 @@ public:
 
   Item_sum_sp(THD *thd, Name_resolution_context *context_arg, sp_name *name,
               sp_head *sp, List<Item> &list);
+  Item_sum_sp(THD *thd, Item_sum_sp *item);
 
   enum Sumfunctype sum_func () const
   {
@@ -1361,6 +1362,7 @@ public:
   }
   Item *get_copy(THD *thd)
   { return get_item_copy<Item_sum_sp>(thd, this); }
+  Item *copy_or_same(THD *thd);
 };
 
 /* Items to get the value of a stored sum function */