src/test/run-pass/union/union-basic.rs

// Copyright 2016 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.

// aux-build:union.rs

extern crate union;
use std::mem::{size_of, align_of, zeroed};

union U {
    a: u8,
    b: u16
}

fn local() {
    assert_eq!(size_of::<U>(), 2);
    assert_eq!(align_of::<U>(), 2);

    let u = U { a: 10 };
    unsafe {
        assert_eq!(u.a, 10);
        let U { a } = u;
        assert_eq!(a, 10);
    }

    let mut w = U { b: 0 };
    unsafe {
        assert_eq!(w.a, 0);
        assert_eq!(w.b, 0);
        w.a = 1;
        assert_eq!(w.a, 1);
        assert_eq!(w.b.to_le(), 1);
    }
}

fn xcrate() {
    assert_eq!(size_of::<union::U>(), 2);
    assert_eq!(align_of::<union::U>(), 2);

    let u = union::U { a: 10 };
    unsafe {
        assert_eq!(u.a, 10);
        let union::U { a } = u;
        assert_eq!(a, 10);
    }

    let mut w = union::U { b: 0 };
    unsafe {
        assert_eq!(w.a, 0);
        assert_eq!(w.b, 0);
        w.a = 1;
        assert_eq!(w.a, 1);
        assert_eq!(w.b.to_le(), 1);
    }
}

fn main() {
    local();
    xcrate();
}