BUG #13391: when use in/= & subquery, non exists column can elected.

The following bug has been logged on the website:

Bug reference: 13391
Logged by: digoal
Email address: digoal(at)126(dot)com
PostgreSQL version: 9.4.2
Operating system: CentOS 6.x x64
Description:

when use in/= & subquery, non exists column can elected.
for exp:
postgres=# create table table1 (c1 int, c2 int, c3 int, c4 text);
CREATE TABLE
postgres=# create table table2 (id int);
CREATE TABLE
postgres=# insert into table1 values (1,2,3,'test');
INSERT 0 1
postgres=# insert into table1 values (2,3,4,'test');
INSERT 0 1
postgres=# insert into table2 values (100);
INSERT 0 1

c1 column not exists in table2, but when table2 in subquery, it can
elected?
postgres=# explain (analyze,verbose) select * from table1 where c1 = (select
c1 from table2 limit 1);
QUERY PLAN

---------------------------------------------------------------------------------------------------------------------------
Seq Scan on public.table1 (cost=0.00..116.59 rows=23 width=44) (actual
time=0.020..0.023 rows=2 loops=1)
Output: table1.c1, table1.c2, table1.c3, table1.c4
Filter: (table1.c1 = (SubPlan 1))
SubPlan 1
-> Limit (cost=0.00..0.01 rows=1 width=0) (actual time=0.003..0.003
rows=1 loops=2)
Output: (table1.c1)
-> Seq Scan on public.table2 (cost=0.00..112.30 rows=10230
width=0) (actual time=0.002..0.002 rows=1 loops=2)
Output: table1.c1
Planning time: 0.169 ms
Execution time: 0.070 ms
(10 rows)

postgres=# explain (analyze,verbose) select * from table1 where c1 in
(select c1 from table2 limit 1);
QUERY PLAN

---------------------------------------------------------------------------------------------------------------------------
Seq Scan on public.table1 (cost=0.00..97.34 rows=2270 width=44) (actual
time=0.018..0.022 rows=2 loops=1)
Output: table1.c1, table1.c2, table1.c3, table1.c4
Filter: (SubPlan 1)
SubPlan 1
-> Limit (cost=0.00..0.01 rows=1 width=0) (actual time=0.003..0.003
rows=1 loops=2)
Output: (table1.c1)
-> Seq Scan on public.table2 (cost=0.00..112.30 rows=10230
width=0) (actual time=0.002..0.002 rows=1 loops=2)
Output: table1.c1
Planning time: 0.102 ms
Execution time: 0.069 ms
(10 rows)

postgres=# select * from table1 where c1 in (select c1 from table2 limit
1);
c1 | c2 | c3 | c4
----+----+----+------
1 | 2 | 3 | test
2 | 3 | 4 | test
(2 rows)

postgres=# select * from table1 where c1 = (select c1 from table2 limit 1);
c1 | c2 | c3 | c4
----+----+----+------
1 | 2 | 3 | test
2 | 3 | 4 | test
(2 rows)
postgres=# explain select c1 from table2 limit 1;
ERROR: column "c1" does not exist
LINE 1: explain select c1 from table2 limit 1;

and there is also can execute with catalog.
postgres=# explain select * from pg_tables where tablename in (select
tablename from tt);
QUERY PLAN

----------------------------------------------------------------------------------
Nested Loop Left Join (cost=0.00..32052.66 rows=51 width=199)
Join Filter: (t.oid = c.reltablespace)
-> Nested Loop Left Join (cost=0.00..32049.20 rows=51 width=139)
Join Filter: (n.oid = c.relnamespace)
-> Seq Scan on pg_class c (cost=0.00..32040.43 rows=51 width=79)
Filter: ((relkind = 'r'::"char") AND (SubPlan 1))
SubPlan 1
-> Seq Scan on tt (cost=0.00..106.30 rows=9630 width=0)
-> Materialize (cost=0.00..1.15 rows=10 width=68)
-> Seq Scan on pg_namespace n (cost=0.00..1.10 rows=10
width=68)
-> Materialize (cost=0.00..1.04 rows=3 width=68)
-> Seq Scan on pg_tablespace t (cost=0.00..1.03 rows=3 width=68)
(12 rows)

postgres=# explain select tablename from tt;
ERROR: column "tablename" does not exist
LINE 1: explain select tablename from tt;
^
postgres=# \d tt
Table "public.tt"
Column | Type | Modifiers
--------+---------+-----------
id | integer |

^