BUG #8512: Can't use columns I can't read in the where clause of a select

The following bug has been logged on the website:

Bug reference: 8512
Logged by: Kurt Roeckx
Email address: kurt(at)roeckx(dot)be
PostgreSQL version: 9.0.6
Operating system: Linux
Description:

Hi,

When I read the documentation for GRANT, I see:
SELECT

Allows SELECT from any column, or the specific columns listed, of the
specified table, view, or sequence. Also allows the use of COPY TO. This
privilege is also needed to reference existing column values in UPDATE or
DELETE.

I read that as "SELECT field1 from table where field2 = 1" should work if I
have grant select(field1), but not on field2. I'm getting a "permission
denied". If I remove the where clause it of course works.

I'm not sure if the behaviour is expected or not. Maybe I'm reading the
documentation wrong, or maybe the documentation is just wrong. Could
someone please clarify?

Kurt