//#![feature(specialization)]
extern crate serde; // 1.0.78
extern crate serde_json; // 1.0.27
#[macro_use] extern crate serde_derive; // 1.0.78

// #[derive(Debug, Serialize)]
struct X {
    foo: String,
}

trait AlwaysDebug {
    fn always_debug(&self) -> Option<String>;
}

impl<T: std::fmt::Debug> AlwaysDebug for T {
    fn always_debug(&self) -> Option<String> {
        None
    }
}

fn main() {
    let x = X{foo: "Foo Bar".to_string()};
    println!("{:?}", x.always_debug());
    // println!("{:?}", x);
    // println!("{:?}", serde_json::to_string(&x).unwrap());
}