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, 1 insertions, 0 deletions

diff --git a/sql/item_subselect.cc b/sql/item_subselect.cc
index d93f6501ebb..4e6b168c9e9 100644
--- a/sql/item_subselect.cc
+++ b/sql/item_subselect.cc
@@ -1497,6 +1497,7 @@ static Item_result set_row(List<Item> &item_list, Item *item,
     item->max_length= sel_item->max_length;
     res_type= sel_item->result_type();
     item->decimals= sel_item->decimals;
+    item->unsigned_flag= sel_item->unsigned_flag;
     *maybe_null= sel_item->maybe_null;
     if (!(row[i]= Item_cache::get_cache(res_type)))
       return STRING_RESULT; // we should return something