text: /*=============================================================================
      Copyright (c) 2014 Eric Niebler
      Copyright (c) 2014,2015,2018 Kohei Takahashi
  
      Distributed under 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)
  ==============================================================================*/
  #if !defined(FUSION_SUPPORT_CONFIG_01092014_1718)
  #define FUSION_SUPPORT_CONFIG_01092014_1718
  
  #include <boost/config.hpp>
  #include <boost/detail/workaround.hpp>
  #include <utility>
  
  #ifndef BOOST_FUSION_GPU_ENABLED
  #define BOOST_FUSION_GPU_ENABLED BOOST_GPU_ENABLED
  #endif
  
  // Enclose with inline namespace because unqualified lookup of GCC < 4.5 is broken.
  //
  //      namespace detail {
  //          struct foo;
  //          struct X { };
  //      }
  //
  //      template <typename T> void foo(T) { }
  //
  //      int main()
  //      {
  //            foo(detail::X());
  //            // prog.cc: In function 'int main()':
  //            // prog.cc:2: error: 'struct detail::foo' is not a function,
  //            // prog.cc:6: error: conflict with 'template<class T> void foo(T)'
  //            // prog.cc:10: error: in call to 'foo'
  //      }
  namespace boost { namespace fusion { namespace detail
  {
      namespace barrier { }
      using namespace barrier;
  }}}
  #define BOOST_FUSION_BARRIER_BEGIN namespace barrier {
  #define BOOST_FUSION_BARRIER_END   }
  
  
  #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1900))
  // All of rvalue-reference ready MSVC don't perform implicit conversion from
  // fundamental type to rvalue-reference of another fundamental type [1].
  //
  // Following example doesn't compile
  //
  //   int i;
  //   long &&l = i; // sigh..., std::forward<long&&>(i) also fail.
  //
  // however, following one will work.
  //
  //   int i;
  //   long &&l = static_cast<long &&>(i);
  //
  // OK, now can we replace all usage of std::forward to static_cast? -- I say NO!
  // All of rvalue-reference ready Clang doesn't compile above static_cast usage [2], sigh...
  //
  // References:
  // 1. https://connect.microsoft.com/VisualStudio/feedback/details/1037806/implicit-conversion-doesnt-perform-for-fund
  // 2. http://llvm.org/bugs/show_bug.cgi?id=19917
  //
  // Tentatively, we use static_cast to forward if run under MSVC.
  #   define BOOST_FUSION_FWD_ELEM(type, value) static_cast<type&&>(value)
  #else
  #   define BOOST_FUSION_FWD_ELEM(type, value) std::forward<type>(value)
  #endif
  
  
  // Workaround for LWG 2408: C++17 SFINAE-friendly std::iterator_traits.
  // http://cplusplus.github.io/LWG/lwg-defects.html#2408
  //
  // - GCC 4.5 enables the feature under C++11.
  //   https://gcc.gnu.org/ml/gcc-patches/2014-11/msg01105.html
  //
  // - MSVC 10.0 implements iterator intrinsics; MSVC 13.0 implements LWG2408.
  #if (defined(BOOST_LIBSTDCXX_VERSION) && (BOOST_LIBSTDCXX_VERSION < 40500) && \
       defined(BOOST_LIBSTDCXX11)) || \
      (defined(BOOST_MSVC) && (1600 <= BOOST_MSVC && BOOST_MSVC < 1900))
  #   define BOOST_FUSION_WORKAROUND_FOR_LWG_2408
  namespace std
  {
      template <typename>
      struct iterator_traits;
  }
  #endif
  
  
  // Workaround for older GCC that doesn't accept `this` in constexpr.
  #if BOOST_WORKAROUND(BOOST_GCC, < 40700)
  #define BOOST_FUSION_CONSTEXPR_THIS
  #else
  #define BOOST_FUSION_CONSTEXPR_THIS BOOST_CONSTEXPR
  #endif
  
  
  // Workaround for compiler which doesn't compile decltype(expr)::type.
  // It expects decltype(expr) deduced as mpl::identity<T>.
  #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1913)) || BOOST_WORKAROUND(BOOST_GCC, < 40700)
  #   include <boost/mpl/identity.hpp>
  #   define BOOST_FUSION_IDENTIFIED_TYPE(parenthesized_expr) \
          boost::mpl::identity<decltype parenthesized_expr>::type::type
  #else
  #   define BOOST_FUSION_IDENTIFIED_TYPE(parenthesized_expr) \
          decltype parenthesized_expr ::type
  #endif
  
  
  // Workaround for GCC 4.6 that rejects defaulted function with noexcept.
  #if BOOST_WORKAROUND(BOOST_GCC, / 100 == 406)
  #   define BOOST_FUSION_NOEXCEPT_ON_DEFAULTED
  #else
  #   define BOOST_FUSION_NOEXCEPT_ON_DEFAULTED BOOST_NOEXCEPT
  #endif
  
  #endif
  