``` rust fn main() { match Some(1) { None @ _ => { } }; //let None = 1; } ``` ``` <anon>:2:19: 2:27 warning: unused variable: `None`, #[warn(unused_variables)] on by default <anon>:2 match Some(1) { None @ _ => { } }; ^~~~~~~~ ``` This is accepted, but probably shouldn't be. (A normal declaration of a variable named None is rejected.)