Re: [boost] Boost.Endian - endian_buffer requirements

Subject: Re: [boost] Boost.Endian - endian_buffer requirements
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2017-01-25 19:05:22

Le 26/01/2017 à 00:04, Vicente J. Botet Escriba a écrit :
>
> Hi,
>
> I wanted to put an Int wrapper inside a endian_buffer and I have some 
> compiler errors depending on whether it is aligned ort not.
>
> http://melpon.org/wandbox/permlink/k52wH2A7yagL2vMP
>
> I was expecting that the endian_buffer would make abstraction of the 
> wrapped type and consider it just as a sequence of bytes, but it seems 
> that it instead works only for some builtin integral.
>
> Am I missing something?
> Was this restriction intended?
> Could this restriction be removed and if yes, how?
>
>
>
I have reached to fix the aligned case adding the customization

Int endian_reverse(Int x)
{
     using boost::endian::endian_reverse;
     return Int {endian_reverse(x.value)};
}

However for the unaligned case there is yet the shift error

prog.cc:30:28:   required from here
/usr/local/boost-1.61.0/include/boost/endian/buffers.hpp:231:26: error: invalid static_cast from type 'Int' to type 'char'
            *(bytes - 1) = static_cast<char>(value);
                           ^~~~~~~~~~~~~~~~~~~~~~~~
/usr/local/boost-1.61.0/include/boost/endian/buffers.hpp:232:59: error: no match for 'operator>>' (operand types are 'Int' and 'int')
            next::store_big(bytes - 1, static_cast<T>(value >> 8));
                                                      ~~~~~~^~~~
/usr/local/boost-1.61.0/include/boost/endian/buffers.hpp:202:5: note: candidate: template<class charT, class traits, boost::endian::order Order, class T, long unsigned int n_bits, boost::endian::align A> std::basic_istream<charT, traits>& boost::endian::operator>>(std::basic_istream<charT, traits>&, boost::endian::endian_buffer<Order, T, n_bits, A>&)
      operator>>(std::basic_istream<charT, traits>& is,
      ^~~~~~~~

http://melpon.org/wandbox/permlink/iPwgdVBV91wsRxeC

Vicente