Macro tyflags 

macro_rules! tyflags {
    ($expr: expr $(,)?) => { ... };
    ($first: expr $(,$expr: expr)* $(,)?) => { ... };
}

Join bitflags at the type level.

let flags = tyflags!(Red|Blue);
assert!(flags.contains(Color::Red));
assert!(flags.contains(Color::Blue));
assert!(!flags.contains(Color::Green));