#![allow(dead_code, deprecated, unused_variables, unused_mut)]
use std::fmt;
use std::net::Ipv4Addr;
struct Foo {
    bar: i32,
    baz: String,
    addr: Ipv4Addr,
}
impl fmt::Debug for Foo {
    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
        fmt.debug_struct("Foo")
            .field("bar", &self.bar)
            .field("baz", &self.baz)
            .field("addr", &format_args!("{}", self.addr))
            .finish()
    }
}
fn main() {
    assert_eq!(
        "Foo { bar: 10, baz: \"Hello World\", addr: 127.0.0.1 }", format!("{:?}", Foo {
        bar : 10, baz : "Hello World".to_string(), addr : Ipv4Addr::new(127, 0, 0, 1), })
    );
}