Server code appears when using only client features

[akonradi-signal]

I have a library that depends on h2 transitively via hyper. The hyper/client feature is enabled but hyper/server is not. My compiled binary contains <h2::server::Peer as h2::proto::Peer>::convert_poll_message which doesn't seem like it should ever be used.

I suspect, but haven't been able to confirm, that this is due to proto::Dyn::convert_poll_message. Since the Rust compiler doesn't know that the Dyn::Server variant is never constructed, it must generate the handling code for it.

Would it be possible to introduce features for "client" and "server" code generation, and then only define the Dyn variant when the respective feature is enabled?