[Boost-users] [integer_traits problem

Subject: [Boost-users] [integer_traits problem
From: Robert Ramey (ramey_at_[hidden])
Date: 2012-05-29 19:26:12

I'm having problems with integer traits when passed an __int64 type data 
type under Visual C++.

I run the following test:

boost::mpl::print<
  boost::mpl::integral_c<
    boost::intmax_t,
    boost::integer_traits<boost::intmax_t>::const_min
  >
> x13;
boost::mpl::print<
  boost::mpl::integral_c<
    boost::intmax_t,
    boost::integer_traits<boost::intmax_t>::const_max
  >
> x8;

What I expect to get for const_min  is:
...
1> T=boost::mpl::integral_c<boost::intmax_t,0x8000000000000000>
...

What I get is:

1>test_fixed_type.cpp
1>c:\boostrelease\boost\mpl\print.hpp(51) : warning C4308: negative integral 
constant converted to unsigned type
1> c:\projects\boost projects\safe_numerics\include\test_fixed_type.cpp(13) 
: see reference to class template instantiation 'boost::mpl::print<T>' being 
compiled
1> with
1> [
1> T=boost::mpl::integral_c<boost::intmax_t,0x800000000>
1> ]
1>c:\boostrelease\boost\mpl\print.hpp(51) : warning C4308: negative integral 
constant converted to unsigned type
1> c:\projects\boost projects\safe_numerics\include\test_fixed_type.cpp(20) 
: see reference to class template instantiation 'boost::mpl::print<T>' being 
compiled
1> with
1> [
1> T=boost::mpl::integral_c<boost::intmax_t,0x7fffffffffffffff>
1> ]

That is the value for const_min is not correct !!.  Note I've tried various 
different types such as using __int64 and also changed the rendering of he 
real vale to _I64_MIN.  None of this seems to fix things.

I've also tried making my own specialzation of integral_c for this type:

template<boost::intmax_t C >
struct integral_c<boost::intmax_t, C>
{
  BOOST_STATIC_CONSTANT(boost::intmax_t, value = C);
  typedef integral_c_tag tag;
  typedef integral_c type;
  typedef boost::intmax_t value_type;
  operator boost::intmax_t() const { return this->value; }
};

Hmmm now I'm wondering about BOOST_STATIC_CONSTANT. and looking at the 
documenation of BOOST_STATIC_CONSTANT shows it's not really expected to work 
on anything wider than an int.

What should one do in a case like this?

Robert Ramey