Reserved words and named function parameters

I've been reviewing Dennis Bjorklund's patch to support named
function parameters:
http://archives.postgresql.org/pgsql-patches/2003-12/msg00176.php

One thing I didn't like about it was that the grammar declared
param_name as plain IDENT, meaning that you could not use even
"unreserved" keywords as param names. One would prefer ColId, but
naturally that causes a truckload of shift and reduce conflicts :-(

After some fooling around I find that these combinations work:

1. Make param_name equate to type_name (allowing IDENT or
unreserved_keyword), and move the following keywords from
"unreserved" to "col_name_keyword" status:
DOUBLE INOUT NATIONAL OUT

2. Make param_name equate to function_name (allowing IDENT,
unreserved_keyword, or func_name_keyword). This requires the
above changes plus moving "IN" from func_name_keyword to fully
reserved status.

Any opinions which to do, or alternate proposals? I'm leaning
slightly to #2, since I doubt anyone is trying to use "IN" as
a function name, but ...

regards, tom lane