roles question

After months of being unable to keep up with what's going on here, I'm
trying to educate myself on some of the latest developments. I was
playing with roles a bit, and I don't know if I'm doing something wrong,
or if I found a hole:

works fine:
regression=# create role testrole2 with user testuser;
CREATE ROLE

doesn't work:
regression=# alter role testrole with user testuser;
ERROR: option "rolemembers" not recognized

works fine:
regression=# alter group testrole add user testuser;
ALTER ROLE

doesn't work (no surprise, is a syntax error):
regression=# alter role testrole add user testuser;
ERROR: syntax error at or near "add" at character 21
LINE 1: alter role testrole add user testuser;

It seems I can create a role with a user, and I can use ALTER GROUP
syntax to add a user to a role, but I can't figure out how to add a user
to a role using ALTER ROLE.

Similarly, these might be just plain abuse of the new syntax, but appear
to be allowed by gram.y:

regression=# alter user testuser in role testrole;
ERROR: option "addroleto" not recognized
regression=# alter user testuser in group testrole;
ERROR: option "addroleto" not recognized

Thanks,

Joe