src/test/ui/union/union-derive-eq.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.

#![feature(untagged_unions)]

#[derive(Eq)] // OK
union U1 {
    a: u8,
}

impl PartialEq for U1 { fn eq(&self, rhs: &Self) -> bool { true } }

#[derive(PartialEq)]
struct PartialEqNotEq;

#[derive(Eq)]
union U2 {
    a: PartialEqNotEq, //~ ERROR the trait bound `PartialEqNotEq: std::cmp::Eq` is not satisfied
}

impl PartialEq for U2 { fn eq(&self, rhs: &Self) -> bool { true } }

fn main() {}