feat(gossipsub): deprecate Rpc in preparation for making it private

[thomaseizinger]

Description

Notes & open questions

Change checklist

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• A changelog entry has been made in the appropriate crates

[mxinden]

Is Rpc used outside of the communication between the NetworkBehaviour and the ConnectionHandler implementation? In other words, is Rpc even used by any user code? If not, I suggest we don't treat removal of Rpc as a breaking change.

[thomaseizinger]

Is Rpc used outside of the communication between the NetworkBehaviour and the ConnectionHandler implementation? In other words, is Rpc even used by any user code? If not, I suggest we don't treat removal of Rpc as a breaking change.

It is not but we don't necessarily know that :)

Is there much harm in deprecating it first?

[jxs]

Thanks Thomas!

[mxinden]

Is Rpc used outside of the communication between the NetworkBehaviour and the ConnectionHandler implementation? In other words, is Rpc even used by any user code? If not, I suggest we don't treat removal of Rpc as a breaking change.

It is not but we don't necessarily know that :)

Is there much harm in deprecating it first?

No harm in deprecating first. Just trying to find consensus for when we make a "breaking" change to it.

[thomaseizinger]

The rule of thumb I often apply is: If somebody does depend on it, can they fix it easily? Activating a feature that used to be default? Yes. Access a now private type, no.