Fixed BUG#8937: Stored Procedure: AVG() works as SUM() in SELECT ... INTO statement

mysql-test/r/sp.result:
  New test case for BUG#8937.
mysql-test/t/sp.test:
  New test case for BUG#8937.
sql/item_sum.h:
  Added val_int() method for Item_sum_avg for forced int types (in SPs for instance),
  otherwise Item_sum_sum::val_int() is used.

mysql-test/r/sp.result

@@ -2736,4 +2736,23 @@ call bug8849()|
 call bug8849()|
 drop procedure bug8849|
 drop tables t3,t4,t5|
+drop procedure if exists bug8937|
+create procedure bug8937()
+begin
+declare s,x,y,z int;
+declare a float;
+select sum(data),avg(data),min(data),max(data) into s,x,y,z from t1;
+select s,x,y,z;
+select avg(data) into a from t1;
+select a;
+end|
+delete from t1|
+insert into t1 (data) values (1), (2), (3), (4), (6)|
+call bug8937()|
+s	x	y	z
+16	3	1	6
+a
+3.2000
+drop procedure bug8937|
+delete from t1|
 drop table t1,t2;

mysql-test/t/sp.test

@@ -3330,8 +3330,32 @@ call bug8849()|
 drop procedure bug8849|
 drop tables t3,t4,t5|
 
+#
+# BUG#8937: Stored Procedure: AVG() works as SUM() in SELECT ... INTO statement
+#
+--disable_warnings
+drop procedure if exists bug8937|
+--enable_warnings
+create procedure bug8937()
+begin
+  declare s,x,y,z int;
+  declare a float;
+
+  select sum(data),avg(data),min(data),max(data) into s,x,y,z from t1;
+  select s,x,y,z;
+  select avg(data) into a from t1;
+  select a;
+end|
+
+delete from t1|
+insert into t1 (data) values (1), (2), (3), (4), (6)|
+call bug8937()|
+
+drop procedure bug8937|
+delete from t1|
+
 
-# Add bug above this line. Use existing tables t1 and t2 when
+# Add bugs above this line. Use existing tables t1 and t2 when
 # practical, or create table t3, t3 etc temporarily (and drop them).
 delimiter ;|
 drop table t1,t2;

sql/item_sum.h

@@ -356,6 +356,8 @@ public:
   void clear();
   bool add();
   double val_real();
+  // In SPs we might force the "wrong" type with select into a declare variable
+  longlong val_int() { return (longlong)val_real(); }
   my_decimal *val_decimal(my_decimal *);
   String *val_str(String *str);
   void reset_field();