extern crate peg; peg::parser!(grammar foo() for str { rule foo(x: i32, y: rule<()>) = "foo" rule ok() = foo(1, <[_] {}>) rule too_few() = foo(1) //~ ERROR rule too_many() = foo(1, <[_] {}>, 2) //~ ERROR pub rule pub_rule_arg(x: rule<()>) = "foo" //~ ERROR }); fn main() {}