Use a published version of the rust-proto branch

[nrc]

This uses the same code as before, but uses it via crates.io, rather than Git.

PTAL @BusyJay @breeswish

[BusyJay]

I feel worried about it, especially when using protobuf-build in grpc-rs. What's the problem of keeping using a branch?

[nrc]

It means we can't publish kvproto, which blocks us publishing the Rust client.

I think I must make it a feature in any case because of grpcio-compiler.

[siddontang]

oh, what is "nrc-protobuf" 😭

[nrc]

it's a minor fork of rust-proto to use Prost naming conventions and adding support for some TiKV-specific pretty printing

[BusyJay]

I don't feel it right to let rust client to depend on a forked version of rust-proto either.

For "TiKV-specific thing", we can leave it inside TiKV project. For naming conventions, we better discussing with rust-protobuf project and get it merged into the project instead of creating a new one.

[nrc]

I don't think they will accept the naming changes - it would be a big breaking change. OTOH, not using those changes makes supporting both Prost and rust-proto very messy.

I agree it is sub-optimal to use a forked version, but we are already doing that, the only change here is to use a published version of the fork.

And to clarify, if we want to publish KvProto, then we can't depend on Git repos - it is not allowed by crates.io. Whereas depending on a fork is sub-optimal, but not impossible (and we already use a forked version of GRPC among other things, which seems worse to me).

[BusyJay]

rust-protobuf supports customization, I don't think it has to be a breaking change.

https://github.com/stepancheg/rust-protobuf/blob/53dc4ae8b2d20b3e6cb971c68042968a45d23882/protobuf-codegen/src/customize.rs#L10-L44

Forked version of gRPC is not the same use case here. Almost all changes to the forked are just bugfix cherry-picks, we don't mean to introduce any custom features to the forked version. And it will not introduce a different crate or make different types.