rust/src/test/run-pass/impl-trait/issue-42479.rs

// Copyright 2017 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.

// run-pass

use std::iter::once;

struct Foo {
    x: i32,
}

impl Foo {
    fn inside(&self) -> impl Iterator<Item = &i32> {
        once(&self.x)
    }
}

fn main() {
    println!("hi");
}