keep old engine & JOIN if we changed subquery Item (Bug #3646)

mysql-test/r/subselect.result:
  ALL/ANY test
mysql-test/t/subselect.test:
  ALL/ANY test
sql/item_subselect.cc:
  keep old engine & JOIN if we changed subquery Item, which allow avoid second all SELECT items fix_fields call with pervios clean up (because of second setup_tables which remove table->key_use and maybe something else)
  keep list when we change Item in SELECT list
  processing inserted max/min function (now JOIN::prepare will be called only once)
  methods of changing item for subselect engines
sql/item_subselect.h:
  change item & results procedure
sql/item_sum.cc:
  Item_sum_hybrid::clear moved to .cc file (to keep .h clean and to make inserving/removing debug info easy)
sql/item_sum.h:
  Item_sum_hybrid::clear moved to .cc file (to keep .h clean and to make inserving/removing debug info easy)
sql/sql_lex.cc:
  note about new method
sql/sql_lex.h:
  method for changing result of UNION JOINs
sql/sql_select.cc:
  method for changing result in JOIN
sql/sql_select.h:
  method for changing result in JOIN
sql/sql_union.cc:
  method for changing result in JOIN

1 files changed, 29 insertions, 0 deletions

diff --git a/sql/sql_union.cc b/sql/sql_union.cc
index 63638b618d9..de3eeec0db0 100644
--- a/sql/sql_union.cc
+++ b/sql/sql_union.cc
@@ -555,3 +555,32 @@ void st_select_lex_unit::reinit_exec_mechanism()
   }
 #endif
 }
+
+
+/*
+  change select_result object of unit
+
+  SYNOPSIS
+    st_select_lex_unit::change_result()
+    result	new select_result object
+    old_result	old select_result object
+
+  RETURN
+    0 - OK
+    -1 - error
+*/
+
+int st_select_lex_unit::change_result(select_subselect *result,
+				      select_subselect *old_result)
+{
+  int res= 0;
+  for (SELECT_LEX *sl= first_select_in_union(); sl; sl= sl->next_select())
+  {
+    if (sl->join && sl->join->result == old_result)
+      if ((res= sl->join->change_result(result)))
+	return (res);
+  }
+  if (fake_select_lex && fake_select_lex->join)
+    res= fake_select_lex->join->change_result(result);
+  return (res);
+}