Removing the "thd" argument from Item::create_field_for_create_select().

"thd" is available through the "table" argument, as table->in_use.

Backporting (partially) from 10.2.

sql/item.h

@@ -1023,7 +1023,7 @@ class Item: public Value_source,
   virtual Field *get_tmp_table_field() { return 0; }
   /* This is also used to create fields in CREATE ... SELECT: */
   virtual Field *tmp_table_field(TABLE *t_arg) { return 0; }
-  virtual Field *create_field_for_create_select(THD *thd, TABLE *table);
+  virtual Field *create_field_for_create_select(TABLE *table);
   virtual Field *create_field_for_schema(THD *thd, TABLE *table);
   virtual const char *full_name() const { return name ? name : "???"; }
   const char *field_name_or_null()

sql/item_func.h

@@ -175,7 +175,7 @@ class Item_func :public Item_func_or_sum
   friend class udf_handler;
   Field *tmp_table_field() { return result_field; }
   Field *tmp_table_field(TABLE *t_arg);
-  Field *create_field_for_create_select(THD *thd, TABLE *table)
+  Field *create_field_for_create_select(TABLE *table)
   {
     return result_type() != STRING_RESULT ?
            tmp_table_field(table) :
@@ -1762,7 +1762,7 @@ class Item_func_set_user_var :public Item_func_user_var
   bool update();
   bool fix_fields(THD *thd, Item **ref);
   void fix_length_and_dec();
-  Field *create_field_for_create_select(THD *thd, TABLE *table)
+  Field *create_field_for_create_select(TABLE *table)
   {
     return result_type() != STRING_RESULT ?
            tmp_table_field(table) :

sql/sql_insert.cc

@@ -3924,10 +3924,10 @@ void select_insert::abort_result_set() {
   CREATE TABLE (SELECT) ...
 ***************************************************************************/
 
-Field *Item::create_field_for_create_select(THD *thd, TABLE *table)
+Field *Item::create_field_for_create_select(TABLE *table)
 {
   Field *def_field, *tmp_field;
-  return create_tmp_field(thd, table, this, type(),
+  return create_tmp_field(table->in_use, table, this, type(),
                           (Item ***) 0, &tmp_field, &def_field, 0, 0, 0, 0);
 }
 
@@ -4002,7 +4002,7 @@ static TABLE *create_table_from_items(THD *thd,
 
   while ((item=it++))
   {
-    Field *tmp_field= item->create_field_for_create_select(thd, &tmp_table);
+    Field *tmp_field= item->create_field_for_create_select(&tmp_table);
 
     if (!tmp_field)
       DBUG_RETURN(NULL);