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, 21 insertions, 0 deletions

diff --git a/sql/set_var.cc b/sql/set_var.cc
index 53a7d2ad39a..24e4e63e9cf 100644
--- a/sql/set_var.cc
+++ b/sql/set_var.cc
@@ -788,12 +788,33 @@ int set_var::light_check(THD *thd)
   Consider set_var::check() method if there is a need to return
   an error due to logics.
 */
+
 int set_var::update(THD *thd)
 {
   return value ? var->update(thd, this) : var->set_default(thd, this);
 }
 
 
+set_var::set_var(THD *thd, enum_var_type type_arg, sys_var *var_arg,
+                 const LEX_STRING *base_name_arg, Item *value_arg)
+  :var(var_arg), type(type_arg), base(*base_name_arg)
+{
+  /*
+    If the set value is a field, change it to a string to allow things like
+    SET table_type=MYISAM;
+  */
+  if (value_arg && value_arg->type() == Item::FIELD_ITEM)
+  {
+    Item_field *item= (Item_field*) value_arg;
+    // names are utf8
+    if (!(value= new (thd->mem_root) Item_string_sys(thd, item->field_name)))
+      value=value_arg;                        /* Give error message later */
+  }
+  else
+    value=value_arg;
+}
+
+
 /*****************************************************************************
   Functions to handle SET @user_variable=const_expr
 *****************************************************************************/