Create automated mechanism for C/Rust types to stay in sync
In transitioning parts of tor to Rust, some parts of the code will either need to temporarily exist in both C and Rust (such as protover), or will be highly coupled (such as enums that are passed between the FFI boundary).
It would be good to automatically verify these areas of the code don't get out of sync. This could either be a post-hoc verifier, or a generator that takes a higher-level specification and generates both C and Rust types.
Ideally, the coupling between C and Rust will be as minimal as possible, so this probably does not need to be a heavyweight solution.