Macro polymorphic_constant 

macro_rules! polymorphic_constant {
    ($(#[$attr:meta])* ($($vis:tt)*) const $name:ident : $( $numeric_type:ident )|* = $lit:literal; $($nextLine:tt)*) => { ... };
    ($(#[$attr:meta])* const $($t:tt)*) => { ... };
    ($(#[$attr:meta])* pub const $($t:tt)*) => { ... };
    ($(#[$attr:meta])* pub ($($vis:tt)+) const $($t:tt)*) => { ... };
    () => { ... };
}

Define one or more polymorphic numerical constants. A constant X of value 10, available in i32 and u32 will read:

polymorphic_constant! {
    const X: i32 | u32 = 10;
}

and be used like:

let x_i32 = X.i32;