Stage 2 of MDEV-6152:

- Added mem_root to all calls to new Item
- Added private method operator new(size_t size) to Item to ensure that
  we always use a mem_root when creating an item.

This saves use once call to current_thd per Item creation

1 files changed, 2 insertions, 1 deletions

diff --git a/sql/sql_expression_cache.cc b/sql/sql_expression_cache.cc
index f9d2f599804..3ed33d97094 100644
--- a/sql/sql_expression_cache.cc
+++ b/sql/sql_expression_cache.cc
@@ -161,7 +161,8 @@ void Expression_cache_tmptable::init()
     goto error;
   }
 
-  if (!(cached_result= new Item_field(table_thd, cache_table->field[0])))
+  if (!(cached_result= new (table_thd->mem_root)
+        Item_field(table_thd, cache_table->field[0])))
   {
     DBUG_PRINT("error", ("Creating Item_field failed"));
     goto error;