From f91ab7005581d43c34760b2184b5de8f0e906073 Mon Sep 17 00:00:00 2001
From: jzmaddock <jzmaddock@gmail.com>
Date: Wed, 23 Apr 2014 12:50:53 +0100
Subject: [PATCH] Apply fix for issue
 https://svn.boost.org/trac/boost/ticket/9910 which provides a C++11
 conforming version of is_convertible.

---
 include/boost/type_traits/is_convertible.hpp | 42 +++++++++++++++++++-
 test/is_convertible_test.cpp                 | 21 ++++++++++
 2 files changed, 61 insertions(+), 2 deletions(-)

diff --git a/include/boost/type_traits/is_convertible.hpp b/include/boost/type_traits/is_convertible.hpp
index 4ae675d..1f083a7 100644
--- a/include/boost/type_traits/is_convertible.hpp
+++ b/include/boost/type_traits/is_convertible.hpp
@@ -30,7 +30,9 @@
 #if defined(__MWERKS__)
 #include <boost/type_traits/remove_reference.hpp>
 #endif
-
+#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+#  include <boost/utility/declval.hpp>
+#endif
 #endif // BOOST_IS_CONVERTIBLE
 
 // should be always the last #include directive
@@ -52,7 +54,43 @@ namespace boost {
 
 namespace detail {
 
-#if defined(__BORLANDC__) && (__BORLANDC__ < 0x560)
+#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+
+   // This is a C++11 conforming version:
+
+   template <class A, class B, class C>
+   struct or_helper
+   {
+      static const bool value = (A::value || B::value || C::value);
+   };
+
+   template<typename From, typename To, bool b = or_helper<boost::is_void<From>, boost::is_function<To>, boost::is_array<To> >::value>
+   struct is_convertible_basic_impl
+   {
+      // Nothing converts to function or array, but void converts to void:
+      static const bool value = is_void<To>::value; 
+   };
+
+   template<typename From, typename To>
+   class is_convertible_basic_impl<From, To, false>
+   {
+      typedef char one;
+      typedef int  two;
+
+      template<typename To1>
+      static void test_aux(To1);
+
+      template<typename From1, typename To1>
+      static decltype(test_aux<To1>(boost::declval<From1>()), one()) test(int);
+
+      template<typename, typename>
+      static two test(...);
+
+   public:
+      static const bool value = sizeof(test<From, To>(0)) == 1;
+   };
+
+#elif defined(__BORLANDC__) && (__BORLANDC__ < 0x560)
 //
 // special version for Borland compilers
 // this version breaks when used for some
diff --git a/test/is_convertible_test.cpp b/test/is_convertible_test.cpp
index 6378a18..9bcc3e0 100644
--- a/test/is_convertible_test.cpp
+++ b/test/is_convertible_test.cpp
@@ -56,6 +56,20 @@ struct bug_5271b
 
 #endif
 
+#if ((!defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)) || defined(BOOST_IS_CONVERTIBLE)) && !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
+struct bug9910
+{
+   bug9910() = default;
+   bug9910(const bug9910&) = delete; // or private: A(const A&) = default;
+};
+struct Ref_bug9910 
+{ 
+   // proxy reference to bug9910
+   operator bug9910& () { return *_ptr; }
+   bug9910* _ptr;
+};
+#endif
+
 TT_TEST_BEGIN(is_convertible)
 
 BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<Derived,Base>::value), true);
@@ -192,5 +206,12 @@ BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<int, bug_5271a>::value), fal
 BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<int, bug_5271b>::value), true);
 #endif
 
+#if ((!defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)) || defined(BOOST_IS_CONVERTIBLE)) && !defined(BOOST_NO_CXX11_DELETED_FUNCTIONS)
+#ifndef _MSC_VER
+// MSVC gives the wrong answer here, see https://connect.microsoft.com/VisualStudio/feedback/details/858956/std-is-convertible-returns-incorrect-value
+BOOST_CHECK_INTEGRAL_CONSTANT((::tt::is_convertible<Ref_bug9910, bug9910>::value), false);
+#endif
+#endif
+
 TT_TEST_END