[GENERAL] incomplete CTE declaration and "column reference x is ambiguous"

[Marc Mamin]

Hello,

I've lost some time to debug a large Query with many CTE.
I couldn't  really believe the error message.

it was correct after all , though surprising.
 a short version to illustrate my error:

WITH t1 (a,b) AS (
         SELECT
                        1 as x,
                2 as a,
                3 as b
        )
select * from t1 WHERE b =0

ERROR: column reference "b" is ambiguous.


It would be nice, if extra undeclared columns would not be visible outside the 
CTE.

regards,

Marc Mamin