struct Backtrace;

trait Fail {

}

struct Error {
    pub(crate) inner: Box<Inner<Fail>>,
}

struct Inner<F: ?Sized + Fail> {
    backtrace: Backtrace,
    failure: F,
}

struct Ha(u32);

impl Fail for Ha {

}

fn main() {
    let ha = Ha(12);

    let er = Error {
    inner: Box::new(Inner{backtrace: Backtrace,failure:ha })

    };
}