For any larger project I would recommend working with a cargo workspace to compile as little as possible on each check/test/run/build.

Then you can build a DAG of crates and stick e.g. the Protobuf stuff in its own separate corner where it only needs to be recompiled on full rebuilds or when you work on it.

Feels a bit shitty to have to resort to managing crates instead of modules simply due to the compile times, but it is what it is.

https://doc.rust-lang.org/cargo/reference/workspaces.html

Yeah, second that. This is just release management best practice.

And it makes total sense to me, it’s a way of organizing your dependency graph by the lifetimes of your components.

This will also simplify testing, development, and audit. You won’t need to recompile autogen schemas as often as the business logic implementation anyway. Depending on artifacts pushed through a release pipeline is even more reliable. You can QA everything in guaranteed isolation while keeping it conveniently a workspace monorepo.

If only someone had a way of automating this! Say perhaps using some kind of digital computer...

I wish rustc could automatically build a DAG of “smallest group of modules with cyclic references” and use that as a compilation unit, but that's unfortunately not the case so far and it won't until someone steps up to build such a system.