odr.h

// Copyright (c) Microsoft. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
#pragma once
 
#include <bond/core/config.h>
 
#include <boost/assert.hpp>
 
namespace bond
{
 
namespace detail
{
 
template <typename T>
struct counter
{
    counter()
    {
        // This assert indicates violation of One Definition Rule for T.
        BOOST_ASSERT(!value++);
    }
 
    static int value;
};
 
 
template <typename T>
int counter<T>::value;
 
}
 
 
template <typename One, typename Variant>
struct one_definition
{
    static detail::counter<One> value;
};
 
 
template <typename One, typename Variant>
detail::counter<One> one_definition<One, Variant>::value;
 
 
}