Macro reverse_decode

macro_rules! reverse_decode {
    ($reader:ident, $s:ident;) => { ... };
    ($reader:ident, $s:ident; $first:ident: $first_ty:ty $(, $rest:ident: $rest_ty:ty)*) => { ... };
}

🔬This is a nightly-only experimental API. (proc_macro_internals #27812)