Fix bug lp:782305

Analysis:
Both the wrong result and the valgrind warning were a result
of incomplete cleanup of the MIN/MAX subquery rewrite. At the
first execution of the query, the non-aggregate subquery is
transformed into an aggregate MIN/MAX subquery. During the
fix_fields phase of the MIN/MAX function, it sets the property
st_select_lex::with_sum_func to true.

The second execution of the query finds this flag to be ON.
When optimization reaches the same MIN/MAX subquery
transformation, it tests if the subquery is an aggregate or not.
Since select_lex->with_sum_func == true from the previous
execution, the transformation executes the second branch that
handles aggregate subqueries. This substitutes the subquery
Item into a Item_maxmin_subselect. At the same time elsewhere
it is assumed that the subquery Item is of type
Item_allany_subselect. Ultimately this results in casting the
actual object to the wrong class, and calling the wrong
any_value() method from empty_underlying_subquery().

Solution:
Cleanup the st_select_lex::with_sum_func property in the case
when the MIN/MAX transformation was performed for a non-aggregate
subquery, so that the transformation can be repeated.

1 files changed, 30 insertions, 0 deletions

diff --git a/mysql-test/r/subselect4.result b/mysql-test/r/subselect4.result
index 9ea790ac800..bfd5872acf2 100644
--- a/mysql-test/r/subselect4.result
+++ b/mysql-test/r/subselect4.result
@@ -2060,4 +2060,34 @@ WHERE t1.f4 IN ( SELECT f4 FROM t2 ) ;
 f4
 set @@optimizer_switch = @old_optimizer_switch;
 drop table t1, t2, t3;
+#
+# LP BUG#782305: Wrong result/valgrind warning in Item_sum_hybrid::any_value()
+#
+CREATE TABLE t1 ( f1 int) ;
+INSERT INTO t1 VALUES (2),(3);
+CREATE TABLE t2 (f2 int) ;
+INSERT INTO t2 VALUES (2),(3);
+PREPARE st1 FROM '
+SELECT * FROM t2
+WHERE f2 <= SOME ( SELECT f1 FROM t1 );
+';
+EXECUTE st1;
+f2
+2
+3
+EXECUTE st1;
+f2
+2
+3
+PREPARE st2 FROM '
+SELECT * FROM t2
+WHERE f2 <= SOME (SELECT f1-2 FROM t1 UNION SELECT f1-1 FROM t1);
+';
+EXECUTE st2;
+f2
+2
+EXECUTE st2;
+f2
+2
+drop table t1, t2;
 set optimizer_switch=@subselect4_tmp;