rust/src/test/run-pass/trait-inheritance-call-bound-inherited.rs

// Copyright 2012 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 Foo { fn f(&self) -> isize; }
trait Bar : Foo { fn g(&self) -> isize; }

struct A { x: isize }

impl Foo for A { fn f(&self) -> isize { 10 } }
impl Bar for A { fn g(&self) -> isize { 20 } }

// Call a function on Foo, given a T: Bar
fn gg<T:Bar>(a: &T) -> isize {
    a.f()
}

pub fn main() {
    let a = &A { x: 3 };
    assert_eq!(gg(a), 10);
}