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, 25 insertions, 2 deletions

diff --git a/sql/sql_select.cc b/sql/sql_select.cc
index 5db4a0042ea..aeab7a9719c 100644
--- a/sql/sql_select.cc
+++ b/sql/sql_select.cc
@@ -1585,8 +1585,7 @@ mysql_select(THD *thd, Item ***rref_pointer_array,
       if (select_lex->linkage != GLOBAL_OPTIONS_TYPE)
       {
 	//here is EXPLAIN of subselect or derived table
-	join->result= result;
-	if (!join->procedure && result->prepare(join->fields_list, unit))
+	if (join->change_result(result))
 	{
 	  DBUG_RETURN(-1);
 	}
@@ -9514,3 +9513,27 @@ void st_select_lex::print(THD *thd, String *str)
 
   // PROCEDURE unsupported here
 }
+
+
+/*
+  change select_result object of JOIN
+
+  SYNOPSIS
+    JOIN::change_result()
+    res		new select_result object
+
+  RETURN
+    0 - OK
+    -1 - error
+*/
+
+int JOIN::change_result(select_result *res)
+{
+  DBUG_ENTER("JOIN::change_result");
+  result= res;
+  if (!procedure && result->prepare(fields_list, select_lex->master_unit()))
+  {
+    DBUG_RETURN(-1);
+  }
+  DBUG_RETURN(0);
+}