Bug #7498 User variable SET saves SIGNED BIGINT as UNSIGNED BIGINT

- Add unsigned flag to user_var_entry, used when 'type' is INT_RESULT
- Propagate unsigned flag from the query executed by Item_single_row_subselect


mysql-test/r/user_var.result:
  Update test results
mysql-test/t/user_var.test:
  Add test case
sql/item_func.cc:
  Add unsigned_flag to user_var_entry. Used when 'type' is INT_RESULT
  Pass unsigned_flag to 'update_hash' if type is INT_RESULT
sql/item_func.h:
  Removed unused variable save_buff
  Add parameter unsigned_arg to 'update_hash'
sql/item_subselect.cc:
  Propagate unsigned_flag to Item_singlerow_subselect from the items in the select to the cached items.
sql/sql_class.h:
  Add unsigned_flag to user_var_entry. Used when 'type' is INT_RESULT

1 files changed, 2 insertions, 4 deletions

diff --git a/sql/item_func.h b/sql/item_func.h
index a91d93be8c6..8f90626ad26 100644
--- a/sql/item_func.h
+++ b/sql/item_func.h
@@ -1154,8 +1154,6 @@ class Item_func_set_user_var :public Item_func
     String *vstr;
     my_decimal *vdec;
   } save_result;
-  String save_buff;
-  
 
 public:
   LEX_STRING name; // keep it public
@@ -1166,8 +1164,8 @@ public:
   longlong val_int();
   String *val_str(String *str);
   my_decimal *val_decimal(my_decimal *);
-  bool update_hash(void *ptr, uint length, enum Item_result type, 
-  		   CHARSET_INFO *cs, Derivation dv);
+  bool update_hash(void *ptr, uint length, enum Item_result type,
+  		   CHARSET_INFO *cs, Derivation dv, bool unsigned_arg= 0);
   bool check();
   bool update();
   enum Item_result result_type () const { return cached_result_type; }