BUG#21477 "memory overruns for certain kinds of subqueries":

make st_select_lex::setup_ref_array() take into account that 
Item_sum-descendant objects located within descendant SELECTs
may be added into ref_pointer_array.


sql/item_sum.cc:
  BUG#21477 "memory overruns for certain kinds of subqueries":
  Make SELECT_LEX::n_sum_items contain # of Item_sum-derived objects
  that exist within this SELECT.
sql/sql_lex.h:
  BUG#21477 "memory overruns for certain kinds of subqueries":
  Add SELECT_LEX::n_sum_items and SELECT_LEXT::n_child_sum_items.
sql/sql_yacc.yy:
  BUG#21477 "memory overruns for certain kinds of subqueries":
  Make SELECT_LEX::n_sum_items contain # of Item_sum-derived objects
  that exist within this SELECT.

1 files changed, 7 insertions, 1 deletions

diff --git a/sql/sql_lex.h b/sql/sql_lex.h
index 220d928ccf7..fe6d60a218d 100644
--- a/sql/sql_lex.h
+++ b/sql/sql_lex.h
@@ -548,6 +548,12 @@ public:
   bool  braces;   	/* SELECT ... UNION (SELECT ... ) <- this braces */
   /* TRUE when having fix field called in processing of this SELECT */
   bool having_fix_field;
+
+  /* Number of Item_sum-derived objects in this SELECT */
+  uint n_sum_items;
+  /* Number of Item_sum-derived objects in children and descendant SELECTs */
+  uint n_child_sum_items;
+
   /* explicit LIMIT clause was used */
   bool explicit_limit;
   /*
@@ -640,7 +646,7 @@ public:
   bool test_limit();
 
   friend void lex_start(THD *thd, uchar *buf, uint length);
-  st_select_lex() {}
+  st_select_lex() : n_sum_items(0), n_child_sum_items(0) {}
   void make_empty_select()
   {
     init_query();