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, 36 insertions, 0 deletions

diff --git a/mysql-test/r/user_var.result b/mysql-test/r/user_var.result
index 7439f9132fb..3a197cd2a47 100644
--- a/mysql-test/r/user_var.result
+++ b/mysql-test/r/user_var.result
@@ -256,3 +256,39 @@ t1	CREATE TABLE `t1` (
   `@first_var` longtext
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
+set @a=18446744071710965857;
+select @a;
+@a
+18446744071710965857
+CREATE TABLE `bigfailure` (
+`afield` BIGINT UNSIGNED NOT NULL
+);
+INSERT INTO `bigfailure` VALUES (18446744071710965857);
+SELECT * FROM bigfailure;
+afield
+18446744071710965857
+select * from (SELECT afield FROM bigfailure) as b;
+afield
+18446744071710965857
+select * from bigfailure where afield = (SELECT afield FROM bigfailure);
+afield
+18446744071710965857
+select * from bigfailure where afield = 18446744071710965857;
+afield
+18446744071710965857
+select * from bigfailure where afield = 18446744071710965856+1;
+afield
+18446744071710965857
+SET @a := (SELECT afield FROM bigfailure);
+SELECT @a;
+@a
+18446744071710965857
+SET @a := (select afield from (SELECT afield FROM bigfailure) as b);
+SELECT @a;
+@a
+18446744071710965857
+SET @a := (select * from bigfailure where afield = (SELECT afield FROM bigfailure));
+SELECT @a;
+@a
+18446744071710965857
+drop table bigfailure;