rust/src/test/ui/run-pass/deriving/deriving-with-repr-packed.rs

// Copyright 2017 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.

// check that derive on a packed struct does not call field
// methods with a misaligned field.

use std::mem;

#[derive(Copy, Clone)]
struct Aligned(usize);

#[inline(never)]
fn check_align(ptr: *const Aligned) {
    assert_eq!(ptr as usize % mem::align_of::<Aligned>(),
               0);
}

impl PartialEq for Aligned {
    fn eq(&self, other: &Self) -> bool {
        check_align(self);
        check_align(other);
        self.0 == other.0
    }
}

#[repr(packed)]
#[derive(Copy, Clone, PartialEq)]
struct Packed(Aligned, Aligned);

#[derive(PartialEq)]
#[repr(C)]
struct Dealigned<T>(u8, T);

fn main() {
    let d1 = Dealigned(0, Packed(Aligned(1), Aligned(2)));
    let ck = d1 == d1;
    assert!(ck);
}