bug: Can not generate plan

[iwanttobepowerful]

postgres=# CREATE TABLE t1(a INT, b INT);
CREATE TABLE
postgres=# CREATE TABLE t2(c INT, d INT);;
CREATE TABLE
postgres=# SELECT * FROM t1 left JOIN t2 ON t2.c <= t1.a;  -- segment fault
postgres=# SELECT * FROM t1 right JOIN t2 ON t2.c = t1.a;  -- segment fault
postgres=# SELECT count(*) FROM t1 right JOIN t2 ON t2.c <= t1.a;  -- infinite loop
postgres=# SELECT count(*) FROM t1 left JOIN t2 ON t2.c <= t1.a;  -- infinite loop
postgres=# SELECT * FROM t1 left JOIN t2 ON t2.c = t1.a; -- ok

Actual Behavior

Can not generate plan.