Macro defn_impl_entry_wrapper

macro_rules! defn_impl_entry_wrapper {
    ($type:ty, $vis:vis $wrapper:ident) => { ... };
}

Creates a struct named $wrapper which wraps ImplEntry<dyn $trait> for the given $trait. This is useful because it allows implementing traits on the ImplEntry<dyn $trait> from external modules. This is an implementation detail of traitcast_to_trait!.