Implementing service in another file

[theo-m]

Hello,
I'm a rust beginner - went through the rustlings exercises and I'm working on my first rust project!
I went through the tutorial, and since I'm working on a well specified project I wanted to start doing things "right". For me that meant implementing my UserService in a dedicated file (hence module (?)).
So I'd have this setup:

# main.rs
use tonic::transport::Server;

use pb::user_service_server::UserServiceServer;
use pb::user_service_server::UserService;
use user::UserServiceImpl;

mod user;

mod pb {
    tonic::include_proto!("app");
}


#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let addr = "[::1]:50051".parse()?;
    let user_service = UserServiceImpl::default();

    Server::builder()
        .add_service(UserServiceServer::new(user_service))
        .serve(addr)
        .await?;

    Ok(())
}

and next to it another file responsible for the implementation of the pb::user_service_server::UserServiceServer:

# user.rs
use tonic::{Request, Response, Status};

mod pb {
    tonic::include_proto!("app");
}

#[derive(Debug, Default)]
pub struct UserServiceImpl {}


#[tonic::async_trait]
impl pb::user_service_server::UserService for UserServiceImpl {
    async fn sync_contacts(
        &self,
        request: Request<pb::SyncContactsInput>,
    ) -> Result<Response<pb::SyncContactsOutput>, Status> {
        unimplemented!()
    }

    async fn onboarding(
        &self,
        request: Request<pb::OnboardingInput>,
    ) -> Result<Response<pb::MeUser>, Status> {
        unimplemented!()
    }

    async fn me(
        &self,
        request: Request<pb::Empty>,
    ) -> Result<Response<pb::MeUser>, Status> {
        unimplemented!()
    }

    async fn get(
        &self,
        request: Request<pb::UserGetInput>,
    ) -> Result<Response<pb::User>, Status> {
        unimplemented!()
    }
}

But compiling fails with:

the trait pb::user_service_server::UserService is not implemented for UserServiceImpl

I've been looking around and saw different solutions on stackoverflow but none made my program compile. In the current state concatening the content of the two files is a compiling program.
Quite randomly stumbled onto this article about the "orphan rule" and it seems like this is the problem I'm hitting?

Could not find examples of tonic use with services split across different modules and files - maybe it's a good addition to the docs?

[theo-m]

I've received pointers from elsewhere:
The solution is to include_proto! only once, e.g. for me

// main.rs
use tonic::transport::Server;

use pb::user_service_server::UserServiceServer;
use pb::user_service_server::UserService;
use user::UserServiceImpl;

mod user;
use user::pb;

// don't do this!
// mod pb {
//    tonic::include_proto!("app");
// }

// user.rs
use tonic::{Request, Response, Status};

// v--- make the thing public! ---v
pub mod pb {
    tonic::include_proto!("app");
}

#[derive(Debug, Default)]
pub struct UserServiceImpl {}

[Ben2146053]

Thanks for this post, I had the same problem.