#![allow(dead_code)] enum Foo { A, B, C, } macro_rules! test_hash { ($foo:expr, $($t:ident => $ord:expr),+ ) => { use self::Foo::*; match $foo { $ ( & $t => $ord, )* }; }; } fn main() { let a = Foo::A; test_hash!(&a, A => 0, B => 1, C => 2); }