src/test/run-pass/dst-trait-tuple.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.


#![allow(unused_features)]
#![feature(box_syntax)]
#![feature(unsized_tuple_coercion)]

type Fat<T: ?Sized> = (isize, &'static str, T);

#[derive(Copy, Clone, PartialEq, Eq, Debug)]
struct Bar;

#[derive(Copy, Clone, PartialEq, Eq)]
struct Bar1 {
    f: isize
}

trait ToBar {
    fn to_bar(&self) -> Bar;
    fn to_val(&self) -> isize;
}

impl ToBar for Bar {
    fn to_bar(&self) -> Bar {
        *self
    }
    fn to_val(&self) -> isize {
        0
    }
}
impl ToBar for Bar1 {
    fn to_bar(&self) -> Bar {
        Bar
    }
    fn to_val(&self) -> isize {
        self.f
    }
}

// x is a fat pointer
fn foo(x: &Fat<ToBar>) {
    assert_eq!(x.0, 5);
    assert_eq!(x.1, "some str");
    assert_eq!(x.2.to_bar(), Bar);
    assert_eq!(x.2.to_val(), 42);

    let y = &x.2;
    assert_eq!(y.to_bar(), Bar);
    assert_eq!(y.to_val(), 42);
}

fn bar(x: &ToBar) {
    assert_eq!(x.to_bar(), Bar);
    assert_eq!(x.to_val(), 42);
}

fn baz(x: &Fat<Fat<ToBar>>) {
    assert_eq!(x.0, 5);
    assert_eq!(x.1, "some str");
    assert_eq!((x.2).0, 8);
    assert_eq!((x.2).1, "deep str");
    assert_eq!((x.2).2.to_bar(), Bar);
    assert_eq!((x.2).2.to_val(), 42);

    let y = &(x.2).2;
    assert_eq!(y.to_bar(), Bar);
    assert_eq!(y.to_val(), 42);

}

pub fn main() {
    let f1 = (5, "some str", Bar1 {f :42});
    foo(&f1);
    let f2 = &f1;
    foo(f2);
    let f3: &Fat<ToBar> = f2;
    foo(f3);
    let f4: &Fat<ToBar> = &f1;
    foo(f4);
    let f5: &Fat<ToBar> = &(5, "some str", Bar1 {f :42});
    foo(f5);

    // Zero size object.
    let f6: &Fat<ToBar> = &(5, "some str", Bar);
    assert_eq!(f6.2.to_bar(), Bar);

    // &*
    //
    let f7: Box<ToBar> = Box::new(Bar1 {f :42});
    bar(&*f7);

    // Deep nesting
    let f1 = (5, "some str", (8, "deep str", Bar1 {f :42}));
    baz(&f1);
    let f2 = &f1;
    baz(f2);
    let f3: &Fat<Fat<ToBar>> = f2;
    baz(f3);
    let f4: &Fat<Fat<ToBar>> = &f1;
    baz(f4);
    let f5: &Fat<Fat<ToBar>> = &(5, "some str", (8, "deep str", Bar1 {f :42}));
    baz(f5);
}