Macro protocol

macro_rules! protocol {
    (
        $( $( #[ doc = $sdoc:literal ] )*
            struct $name:ident <$lt:lifetime> $(: $super:ident)? { $($struct:tt)+ }
        )+
        $(  #[repr($repr:ty)] $( #[ doc = $edoc:literal ] )*
            enum $ename:ident { $($(#[$default:meta])? $emname:ident = $emvalue:literal),+ $(,)? }
        )*
    ) => { ... };
}

Generates a protocol definition from a Rust-like DSL.

LIMITATION: Enums must appear after structs.

struct Foo {
    bar: u8,
    baz: u16 = 123,
}

#[repr(u8)]
enum MyEnum {
    A = 1,
    B = 2,
}