Macro impl_opaque_unique_facade 

macro_rules! impl_opaque_unique_facade {
    (
        $(#[$meta:meta])*
        $vis:vis struct $name:ident,
        $destroy_fn:path $(,)?
    ) => { ... };
}

Declares a zero-sized facade struct for an opaque ktl::unique_ptr-owned C++ object and implements Recyclable for it so it can be held by fbl::UniquePtr.