a fix (bug #11215: BIGINT: can't set DEFAULT to minimum end-range)

sql/item.cc:
  a fix (bug #11215: BIGINT: can't set DEFAULT to minimum end-range)
  Pass unsig=1 to the constructor.

mysql-test/r/type_newdecimal.result

@@ -928,3 +928,9 @@ select * from t1 where a = -0.00;
 a
 0.00
 drop table t1;
+create table t1 (col1 bigint default -9223372036854775808);
+insert into t1 values (default);
+select * from t1;
+col1
+-9223372036854775808
+drop table t1;

mysql-test/t/type_newdecimal.test

@@ -964,3 +964,12 @@ insert into t1 values (0.00);
 select * from t1 where a > -0.00;
 select * from t1 where a = -0.00;
 drop table t1;
+
+#
+# Bug #11215: a problem with LONGLONG_MIN
+#
+
+create table t1 (col1 bigint default -9223372036854775808);
+insert into t1 values (default);
+select * from t1;
+drop table t1;

sql/item.cc

@@ -3573,7 +3573,7 @@ Item *Item_int_with_ref::new_item()
 
 Item_num *Item_uint::neg()
 {
-  Item_decimal *item= new Item_decimal(value, 0);
+  Item_decimal *item= new Item_decimal(value, 1);
   return item->neg();
 }