Missing initializer for member

[mattyclarkson@…]

I have the following error when compiling with my built boost 1.63:

/usr/include/boost/atomic/detail/bitwise_cast.hpp: In instantiation of 'To boost::atomics::detail::bitwise_cast(const From&) [with To = long unsigned int; From = void*]':
/usr/include/boost/atomic/detail/atomic_template.hpp:556:139:   required from here
/usr/include/boost/atomic/detail/bitwise_cast.hpp:39:14: error: missing initializer for member 'boost::atomics::detail::bitwise_cast(const From&) [with To = long unsigned int; From = void*]::<anonymous struct>::to' [-Werror=missing-field-initializers]
     value = {};

The code looks like:

template< typename To, typename From >
BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT
{
    struct
    {
        To to;
    }
    value = {};
    BOOST_ATOMIC_DETAIL_MEMCPY
    (
        &reinterpret_cast< char& >(value.to),
        &reinterpret_cast< const char& >(from),
        (sizeof(From) < sizeof(To) ? sizeof(From) : sizeof(To))
    );
    return value.to;
}

My proposed fix is:

template< typename To, typename From >
BOOST_FORCEINLINE To bitwise_cast(From const& from) BOOST_NOEXCEPT
{
    struct Value
    {
        To to;
        Value() : to() {}
    }
    struct Value value;
    BOOST_ATOMIC_DETAIL_MEMCPY
    (
        &reinterpret_cast< char& >(value.to),
        &reinterpret_cast< const char& >(from),
        (sizeof(From) < sizeof(To) ? sizeof(From) : sizeof(To))
    );
    return value.to;
}

[mattyclarkson@…]

Proposed git format-patch for downloaded source

[Andrey Semashev]

Not all compilers support value initialization properly, so the proposed solution is not quite portable.

The warning should be fixed in ​https://github.com/boostorg/atomic/commit/078639812015b96f64eb88a67a857d12201aab17.