#![feature(rustc_attrs)] macro_rules! check { ($expr: expr) => ( #[rustc_dummy = $expr] //~ ERROR unexpected token: `-0` //~| ERROR unexpected token: `0 + 0` use main as _; ); } check!("0"); // OK check!(0); // OK check!(0u8); //~ ERROR suffixed literals are not allowed in attributes check!(-0); // ERROR, see above check!(0 + 0); // ERROR, see above fn main() {}