Fix for bug #1271: Undefined variable in PASSWORD() function is not

handled correctly

mysql-test/r/func_crypt.result

@@ -7,3 +7,13 @@ old_password('test')	password('test')
 select length(encrypt('test')), encrypt('test','aa');
 length(encrypt('test'))	encrypt('test','aa')
 13	aaqPiZY5xR5l.
+drop table if exists t1;
+create table t1 (name varchar(50), pw varchar(16));
+insert into t1 values ('tom', password('my_pass'));
+set @pass='my_pass';
+select name from t1 where name='tom' and pw=password(@pass);
+name
+tom
+select name from t1 where name='tom' and pw=password(@undefined);
+name
+drop table t1;

mysql-test/t/func_crypt.test

@@ -4,3 +4,12 @@ select length(encrypt('foo', 'ff')) <> 0;
 --replace_result $1$aa$4OSUA5cjdx0RUQ08opV27/ aaqPiZY5xR5l.
 select old_password('test'), password('test');
 select length(encrypt('test')), encrypt('test','aa');
+
+drop table if exists t1;
+create table t1 (name varchar(50), pw varchar(16));
+insert into t1 values ('tom', password('my_pass'));
+set @pass='my_pass';
+select name from t1 where name='tom' and pw=password(@pass);
+select name from t1 where name='tom' and pw=password(@undefined);
+drop table t1;
+

sql/item_func.cc

@@ -2087,7 +2087,7 @@ void Item_func_get_user_var::fix_length_and_dec()
 
 bool Item_func_get_user_var::const_item() const
 {
-  return var_entry && current_thd->query_id != var_entry->update_query_id;
+  return (!var_entry || current_thd->query_id != var_entry->update_query_id);
 }