src/test/run-pass/tag-align-u64.rs

// Copyright 2012-2014 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.


use std::mem;

enum Tag {
    TagInner(u64)
}

struct Rec {
    c8: u8,
    t: Tag
}

fn mk_rec() -> Rec {
    return Rec { c8:0, t:Tag::TagInner(0) };
}

fn is_u64_aligned(u: &Tag) -> bool {
    let p: usize = unsafe { mem::transmute(u) };
    let u64_align = std::mem::min_align_of::<u64>();
    return (p & (u64_align - 1)) == 0;
}

pub fn main() {
    let x = mk_rec();
    assert!(is_u64_aligned(&x.t));
}