{"ast_node_type":"other","tokens":[{"end":85,"kind":"keyword","start":0,"text":"//"}]}
                // Create a placeholder argument for proper arg count (issue #34264).
                p.eat_to_tokens(&[exp!(Comma), exp!(CloseParen)]);
                Ok(dummy_arg(Ident::new(sym::dummy, lo.to(p.prev_token.span)), guar))