Criei um projeto simples para fins educacionais, por isso tenho uma função principal e três característicasBattery, Display eGSM e implementações para eles. Quero que a função principal esteja no arquivo main.rs e as 3 características em outro arquivo chamado phone.rs:

phone.rs

mod phone{
    pub struct Battery{
        model : String,
        hours_idle : i16,
        hours_talk : i16
    }

    pub struct Display{
        size : i16,
        number_of_colors : i32
    }

    pub struct GSM{
        model : String,
        manufactor : String,
        price : f32,
        owner : String,
        battery: Battery,
        display : Display
    }

     impl Battery {
        pub fn new(model : String, hours_idle : i16, hours_talk : i16) -> Battery{
            Battery {model : model, hours_idle : hours_idle ,hours_talk : hours_talk}
        }
        pub fn print(&self){
            println!("Battery model: {}", self.model);
            println!("Hours idle: {}", self.hours_idle);
            println!("hours talk: {}", self.hours_talk);
        }
    }

    impl Display {
        pub fn new(size: i16, number_of_colors : i32) -> Display{
            Display{size : size, number_of_colors : number_of_colors}
        }
        pub fn print(&self){
            println!("size: {}", self.size);
            println!("number_of_colors: {}", self.number_of_colors);
        }
    }

     impl GSM {
        pub fn new(model : String, manufactor : String, price : f32, owner : String, battery : Battery, display : Display) -> GSM{
            GSM{model : model, manufactor : manufactor, price : price, owner : owner, battery : battery, display : display }
        }
        pub fn print(&self){
            println!("Model: {}, Manufactor: {}", self.model, self.manufactor);
            println!("price: {}", self.price);
            println!("owner: {}", self.owner);
            self.battery.print();
            self.display.print();
        }
    }
}

main.rs

pub mod phone;
fn main(){
    let battey = phone::Battery::new("modelBattery".to_string(), 1,2);
    let display =  phone::Display::new(10,20);
    //model : String, manufactor : String, price : f32, owner : String, baterry : Battery, display : Display
    let gsm =  phone::GSM::new("modelPhone".to_string(), "manufactor".to_string(), 100.0, "owner".to_string(), battey, display);
    gsm.print();
}

No começo, tudo estava em um arquivo (main.rs) e tudo funcionava bem (havia alguma diferença, por exemplo, adicioneiphone:: em frente deDisplay, GSM eBattery em main.rs), quando mudei as características e adicioneimod phone{} em phone.rs epub mod phone em main.rs, obtive os seguintes erros do compilador:

src\main.rs:3:18: 3:37 error: failed to resolve. Could not find `Battery` in `phone` [E0433]
src\main.rs:3     let battey = phone::Battery::new("modelBattery".to_string(), 1,2);
                               ^~~~~~~~~~~~~~~~~~~
src\main.rs:3:18: 3:37 help: run `rustc --explain E0433` to see a detailed explanation
src\main.rs:3:18: 3:37 error: unresolved name `phone::Battery::new` [E0425]
src\main.rs:3     let battey = phone::Battery::new("modelBattery".to_string(), 1,2);
                               ^~~~~~~~~~~~~~~~~~~
src\main.rs:3:18: 3:37 help: run `rustc --explain E0425` to see a detailed explanation
src\main.rs:4:20: 4:39 error: failed to resolve. Could not find `Display` in `phone` [E0433]
src\main.rs:4     let display =  phone::Display::new(10,20);
                                 ^~~~~~~~~~~~~~~~~~~
src\main.rs:4:20: 4:39 help: run `rustc --explain E0433` to see a detailed explanation
src\main.rs:4:20: 4:39 error: unresolved name `phone::Display::new` [E0425]
src\main.rs:4     let display =  phone::Display::new(10,20);
                                 ^~~~~~~~~~~~~~~~~~~
src\main.rs:4:20: 4:39 help: run `rustc --explain E0425` to see a detailed explanation
src\main.rs:6:16: 6:31 error: failed to resolve. Could not find `GSM` in `phone` [E0433]
src\main.rs:6     let gsm =  phone::GSM::new("modelPhone".to_string(), "manufactor".to_string(), 100.0, "owner".to_string(), battey, display);
                             ^~~~~~~~~~~~~~~
src\main.rs:6:16: 6:31 help: run `rustc --explain E0433` to see a detailed explanation
src\main.rs:6:16: 6:31 error: unresolved name `phone::GSM::new` [E0425]
src\main.rs:6     let gsm =  phone::GSM::new("modelPhone".to_string(), "manufactor".to_string(), 100.0, "owner".to_string(), battey, display);
                             ^~~~~~~~~~~~~~~
src\main.rs:6:16: 6:31 help: run `rustc --explain E0425` to see a detailed explanation
src\main.rs:7:5: 7:16 error: the type of this value must be known in this context
src\main.rs:7     gsm.print();

Não entendo, pesquisei aqui e no Google, mas não consegui encontrar uma solução. Também recebo muitos avisos de que os métodos phone.rs nunca são usados#[warn(dead_code)], qualquer ajuda é apreciada.