[Boost-users] [Spirit][Math] karma: regression in 1.54 due to argument promotion in math?

Subject: [Boost-users] [Spirit][Math] karma: regression in 1.54 due to argument promotion in math?
From: Igor R (boost.lists_at_[hidden])
Date: 2013-07-30 05:13:56

Hello,

The following code compiles with 1.53, but fails with 1.54 (FreeBSD
9.1, gcc4.2.1):

#include <boost/spirit/include/karma.hpp>
#include <string>
#include <iterator>

int main()
{
  using namespace boost::spirit::karma;
  std::string result;
  std::back_insert_iterator sink(result);
  unsigned short a;
  generate(sink, auto_, a);
}

The error is:
boost/boost/math/tools/promotion.hpp: In instantiation of
'boost::math::tools::promote_args<long double, float, float, float,
float, float>':
boost/boost/math/special_functions/sign.hpp:114:   instantiated from
'int boost::math::signbit(T) [with T = long double]'
boost/boost/spirit/home/support/detail/sign.hpp:47:   instantiated
from 'bool boost::spirit::detail::signbit(T) [with T = long double]'
boost/boost/spirit/home/karma/numeric/detail/numeric_utils.hpp:130:
instantiated from here
boost/boost/math/tools/promotion.hpp:141: error: invalid application
of 'sizeof' to incomplete type
'boost::STATIC_ASSERTION_FAILURE<false>'

I.e., the compilation fails because FreeBSD doesn't supprt "long double" type.
This happens now due to the following changes in
boost/math/special_functions/sign.hpp :

123   template<class T> int (signbit)(T x)
124   {
125      typedef typename detail::fp_traits<T>::type traits;
126      typedef typename traits::method method;
127  -    typedef typename boost::is_floating_point<T>::type fp_tag;
128  -    return detail::signbit_impl(x, method());
127 +    // typedef typename boost::is_floating_point<T>::type fp_tag;
128 +    typedef typename tools::promote_args<T>::type result_type;
129 +    return detail::signbit_impl(static_cast<result_type>(x), method());
130   }

So, what would be the right way to reconcile karma and math?

Thanks,

Igor'.