src/test/compile-fail/associated-types-eq-3.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 equality constraints on associated types. Check we get type errors
// where we should.

pub trait Foo {
    type A;
    fn boo(&self) -> <Self as Foo>::A;
}

struct Bar;

impl Foo for isize {
    type A = usize;
    fn boo(&self) -> usize {
        42
    }
}

fn foo1<I: Foo<A=Bar>>(x: I) {
    let _: Bar = x.boo();
}

fn foo2<I: Foo>(x: I) {
    let _: Bar = x.boo();
    //~^ ERROR mismatched types
    //~| expected type `Bar`
    //~| found type `<I as Foo>::A`
    //~| expected struct `Bar`, found associated type
}


pub fn baz(x: &Foo<A=Bar>) {
    let _: Bar = x.boo();
}


pub fn main() {
    let a = 42;
    foo1(a);
    //~^ ERROR type mismatch resolving
    //~| expected usize
    //~| found struct `Bar`
    baz(&a);
    //~^ ERROR type mismatch resolving
    //~| expected usize
    //~| found struct `Bar`
}