rust/src/test/run-pass/method-recursive-blanket-impl.rs

// Copyright 2014 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.

// Test that we don't trigger on the blanket impl for all `&'a T` but
// rather keep autoderefing and trigger on the underlying impl.  To
// know not to stop at the blanket, we have to recursively evaluate
// the `T:Foo` bound.

use std::markers::Sized;

// Note: this must be generic for the problem to show up
trait Foo<A> {
    fn foo(&self);
}

impl Foo<u8> for [u8] {
    fn foo(&self) {}
}

impl<'a, A, T> Foo<A> for &'a T where T: Foo<A> {
    fn foo(&self) {
        Foo::foo(*self)
    }
}

trait Bar {
    fn foo(&self);
}

struct MyType;

impl Bar for MyType {
    fn foo(&self) {}
}

fn main() {
    let mut m = MyType;
    (&mut m).foo()
}