olap.result:

  Fixed bug #10982.
item.cc:
  Fixed bug #10982. In the function Item_ref::val_decimal
  by mistake the method Item_ref::val_decimal was used
  instead of Item_ref::val_decimal_result.

mysql-test/r/olap.result

@@ -503,7 +503,7 @@ a+1
 NULL
 SELECT a+SUM(a) FROM t1 GROUP BY a WITH ROLLUP;
 a+SUM(a)
-3
+2
 4
 NULL
 SELECT a, a+1 as b FROM t1 GROUP BY a WITH ROLLUP HAVING b > 2;

sql/item.cc

@@ -4358,7 +4358,7 @@ bool Item_ref::get_date(TIME *ltime,uint fuzzydate)
 
 my_decimal *Item_ref::val_decimal(my_decimal *decimal_value)
 {
-  my_decimal *val= (*ref)->val_decimal(decimal_value);
+  my_decimal *val= (*ref)->val_decimal_result(decimal_value);
   null_value= (*ref)->null_value;
   return val;
 }