text: 
  //  (C) Copyright John Maddock 2015.
  //  Use, modification and distribution are subject to the Boost Software License,
  //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
  //  http://www.boost.org/LICENSE_1_0.txt).
  //
  //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
  
  #ifndef BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
  #define BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
  
  #include <cstddef> // size_t
  #include <boost/type_traits/integral_constant.hpp>
  #include <boost/detail/workaround.hpp>
  
  #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
  #include <boost/type_traits/is_abstract.hpp>
  #endif
  
  #if !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1800) && !BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40500)
  
  #include <boost/type_traits/detail/yes_no_type.hpp>
  
  namespace boost{
  
     namespace detail{
  
        struct is_default_constructible_imp
        {
           template<typename _Tp, typename = decltype(_Tp())>
           static boost::type_traits::yes_type test(int);
  
           template<typename>
           static boost::type_traits::no_type test(...);
        };
  #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
        template<class T, bool b>
        struct is_default_constructible_abstract_filter
        {
            static const bool value = sizeof(is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type);
        };
        template<class T>
        struct is_default_constructible_abstract_filter<T, true>
        {
            static const bool value = false;
        };
  #endif
     }
  
  #if BOOST_WORKAROUND(BOOST_GCC_VERSION, < 40700)
     template <class T> struct is_default_constructible : public integral_constant<bool, detail::is_default_constructible_abstract_filter<T, boost::is_abstract<T>::value>::value>{};
  #else
     template <class T> struct is_default_constructible : public integral_constant<bool, sizeof(detail::is_default_constructible_imp::test<T>(0)) == sizeof(boost::type_traits::yes_type)>{};
  #endif
     template <class T, std::size_t N> struct is_default_constructible<T[N]> : public is_default_constructible<T>{};
     template <class T> struct is_default_constructible<T[]> : public is_default_constructible<T>{};
     template <class T> struct is_default_constructible<T&> : public integral_constant<bool, false>{};
  #if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
     template <class T> struct is_default_constructible<T&&> : public integral_constant<bool, false>{};
  #endif
     template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
     template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
     template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
     template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
  
  #else
  
  #include <boost/type_traits/is_pod.hpp>
  
  namespace boost{
  
     // We don't know how to implement this, note we can not use has_trivial_constructor here
     // because the correct implementation of that trait requires this one:
     template <class T> struct is_default_constructible : public is_pod<T>{};
     template <> struct is_default_constructible<void> : public integral_constant<bool, false>{};
     template <> struct is_default_constructible<void const> : public integral_constant<bool, false>{};
     template <> struct is_default_constructible<void volatile> : public integral_constant<bool, false>{};
     template <> struct is_default_constructible<void const volatile> : public integral_constant<bool, false>{};
  
  #endif
  
  } // namespace boost
  
  #endif // BOOST_TT_IS_DEFAULT_CONSTRUCTIBLE_HPP_INCLUDED
  