rust/src/test/compile-fail/E0038.rs

// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

trait Trait {
    fn foo(&self) -> Self;
}

fn call_foo(x: Box<Trait>) {
    //~^ ERROR E0038
    //~| NOTE the trait `Trait` cannot be made into an object
    //~| NOTE method `foo` references the `Self` type in its arguments or return type
    let y = x.foo();
}

fn main() {
}