Function make_agg_arg

src/backend/parser/parse_agg.c:2227–2239

* Convenience function to build dummy argument expressions for aggregates. * * We really only care that an aggregate support function can discover its * actual argument types at runtime using get_fn_expr_argtype(), so it's okay * to use Param nodes that don't correspond to any real Param. */

 * to use Param nodes that don't correspond to any real Param.
 */
static Node *
make_agg_arg(Oid argtype, Oid argcollation)
{
	Param	   *argp = makeNode(Param);

	argp->paramkind = PARAM_EXEC;
	argp->paramid = -1;
	argp->paramtype = argtype;
	argp->paramtypmod = -1;
	argp->paramcollid = argcollation;
	argp->location = -1;
	return (Node *) argp;
}