BUG #18758: Incorrect query result caused by ROLLUP operation

The following bug has been logged on the website:

Bug reference:      18758
Logged by:          Pisces Mar.
Email address:      vectorplanck@gmail.com
PostgreSQL version: 17.2
Operating system:   window10
Description:

create table t1 (c1 char(50));
create table t2 (c1 integer);
select  t1.c1 from t2, t1 group by rollup(t1.c1); -- actual: {null},
expected: {}