Re: REVOKE FROM warning on grantor

Hi,

> https://dev.mysql.com/doc/refman/8.0/en/revoke.html documents an "IF
> EXISTS" option whose documentation reads, in relevant part,
> "Otherwise, REVOKE executes normally; if the user does not exist, the
> statement raises an error."
>
> https://community.snowflake.com/s/article/Access-Control-Error-Message-When-Revoking-a-Non-existent-Role-Grant-From-a-Role-or-User
> is kind of interesting. It says that such commands used to fail with
> an error but that's been changed; now they don't.

It's not about inexistant user. It's not about inexistant membership.
It's about membership you are not allowed to revoke.

ldap2pg goals is to revoke spurious privileges. If ldap2pg find a
spurious membership, it revokes it. Postgres 16 does not revoke some
membership revoked before, and does not fail.

The usual case is: a superuser grants writers role to alice. In
directory, alice is degraded to readers. ldap2pg is not superuser but
has CREATEROLE. ldap2pg applies the changes. In Postgres 15, revocation
is completed. In Postgres 16, alice still has writers privileges and
ldap2pg is not aware of this without clunky checks.

Do you see a security concern here ?

Regards,
Étienne