rust/src/test/ui/issue-35976.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.

mod private {
    pub trait Future {
        fn wait(&self) where Self: Sized;
    }

    impl Future for Box<Future> {
        fn wait(&self) { }
    }
}

//use private::Future;

fn bar(arg: Box<private::Future>) {
    arg.wait();
    //~^ ERROR the `wait` method cannot be invoked on a trait object
    //~| another candidate was found in the following trait, perhaps add a `use` for it:
}

fn main() {

}