From e4d3cba6dd65d54e40751ed1e336cdd761620682 Mon Sep 17 00:00:00 2001
From: jzmaddock <john@johnmaddock.co.uk>
Date: Wed, 7 Feb 2018 19:14:50 +0000
Subject: [PATCH] Binary Operators: switch to the "detection idiom" if the
 compiler supports it. This gives us almost perfect fidelity in the detection
 and solves the known issues for binary operators. Also fixes:
 https://svn.boost.org/trac10/ticket/13012.

---
 .../detail/has_binary_operator.hpp            | 84 +++++++++++++---
 include/boost/type_traits/has_minus.hpp       | 93 ++++++++++++++++++
 .../boost/type_traits/has_minus_assign.hpp    | 95 ++++++++++++++++++-
 3 files changed, 256 insertions(+), 16 deletions(-)

diff --git a/include/boost/type_traits/detail/has_binary_operator.hpp b/include/boost/type_traits/detail/has_binary_operator.hpp
index 039a6bb..3af3657 100644
--- a/include/boost/type_traits/detail/has_binary_operator.hpp
+++ b/include/boost/type_traits/detail/has_binary_operator.hpp
@@ -7,19 +7,7 @@
 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
 
 #include <boost/config.hpp>
-#include <boost/type_traits/detail/yes_no_type.hpp>
-#include <boost/type_traits/integral_constant.hpp>
-#include <boost/type_traits/is_base_of.hpp>
-#include <boost/type_traits/is_const.hpp>
-#include <boost/type_traits/is_convertible.hpp>
-#include <boost/type_traits/is_fundamental.hpp>
-#include <boost/type_traits/is_integral.hpp>
-#include <boost/type_traits/is_pointer.hpp>
-#include <boost/type_traits/is_same.hpp>
-#include <boost/type_traits/is_void.hpp>
-#include <boost/type_traits/remove_cv.hpp>
-#include <boost/type_traits/remove_pointer.hpp>
-#include <boost/type_traits/remove_reference.hpp>
+#include <boost/config/workaround.hpp>
 
 // cannot include this header without getting warnings of the kind:
 // gcc:
@@ -37,12 +25,77 @@
 #   pragma GCC system_header
 #elif defined(BOOST_MSVC)
 #   pragma warning ( push )
-#   pragma warning ( disable : 4018 4244 4547 4800 4804 4805 4913)
+#   pragma warning ( disable : 4018 4244 4547 4800 4804 4805 4913 4133)
 #   if BOOST_WORKAROUND(BOOST_MSVC_FULL_VER, >= 140050000)
 #       pragma warning ( disable : 6334)
 #   endif
 #endif
 
+#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1900)
+
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/type_traits/make_void.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/is_void.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <utility>
+
+namespace boost
+{
+
+   namespace binary_op_detail {
+
+      struct dont_care;
+
+      template <class T, class U, class Ret, class = boost::void_t<>>
+      struct BOOST_JOIN(BOOST_TT_TRAIT_NAME, _ret_imp) : public boost::false_type {};
+
+      template <class T, class U, class Ret>
+      struct BOOST_JOIN(BOOST_TT_TRAIT_NAME, _ret_imp)<T, U, Ret, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() BOOST_TT_TRAIT_OP std::declval<typename add_reference<U>::type>())> >
+         : public boost::integral_constant<bool, ::boost::is_convertible<decltype(std::declval<typename add_reference<T>::type>() BOOST_TT_TRAIT_OP std::declval<typename add_reference<U>::type>()), Ret>::value> {};
+
+      template <class T, class U, class = boost::void_t<> >
+      struct BOOST_JOIN(BOOST_TT_TRAIT_NAME, _void_imp) : public boost::false_type {};
+
+      template <class T, class U>
+      struct BOOST_JOIN(BOOST_TT_TRAIT_NAME, _void_imp)<T, U, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() BOOST_TT_TRAIT_OP std::declval<typename add_reference<U>::type>())> >
+         : public boost::integral_constant<bool, ::boost::is_void<decltype(std::declval<typename add_reference<T>::type>() BOOST_TT_TRAIT_OP std::declval<typename add_reference<U>::type>())>::value> {};
+
+      template <class T, class U, class = boost::void_t<>>
+      struct BOOST_JOIN(BOOST_TT_TRAIT_NAME, _dc_imp) : public boost::false_type {};
+
+      template <class T, class U>
+      struct BOOST_JOIN(BOOST_TT_TRAIT_NAME, _dc_imp)<T, U, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() BOOST_TT_TRAIT_OP std::declval<typename add_reference<U>::type>())> >
+         : public boost::true_type {};
+
+   }
+
+   template <class T, class U = T, class Ret = boost::binary_op_detail::dont_care>
+   struct BOOST_TT_TRAIT_NAME : public boost::binary_op_detail:: BOOST_JOIN(BOOST_TT_TRAIT_NAME, _ret_imp) <T, U, Ret> {};
+   template <class T, class U>
+   struct BOOST_TT_TRAIT_NAME<T, U, void> : public boost::binary_op_detail:: BOOST_JOIN(BOOST_TT_TRAIT_NAME, _void_imp) <T, U> {};
+   template <class T, class U>
+   struct BOOST_TT_TRAIT_NAME<T, U, boost::binary_op_detail::dont_care> : public boost::binary_op_detail:: BOOST_JOIN(BOOST_TT_TRAIT_NAME, _dc_imp) <T, U> {};
+
+
+}
+
+#else
+
+#include <boost/type_traits/detail/yes_no_type.hpp>
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/type_traits/is_base_of.hpp>
+#include <boost/type_traits/is_const.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/is_fundamental.hpp>
+#include <boost/type_traits/is_integral.hpp>
+#include <boost/type_traits/is_pointer.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/type_traits/is_void.hpp>
+#include <boost/type_traits/remove_cv.hpp>
+#include <boost/type_traits/remove_pointer.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
 namespace boost {
 namespace detail {
 
@@ -217,6 +270,9 @@ struct BOOST_TT_TRAIT_NAME : public integral_constant<bool, (::boost::detail::BO
 
 } // namespace boost
 
+#endif
+
 #if defined(BOOST_MSVC)
 #   pragma warning ( pop )
 #endif
+
diff --git a/include/boost/type_traits/has_minus.hpp b/include/boost/type_traits/has_minus.hpp
index 5e13c16..a82618f 100644
--- a/include/boost/type_traits/has_minus.hpp
+++ b/include/boost/type_traits/has_minus.hpp
@@ -9,6 +9,97 @@
 #ifndef BOOST_TT_HAS_MINUS_HPP_INCLUDED
 #define BOOST_TT_HAS_MINUS_HPP_INCLUDED
 
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+// cannot include this header without getting warnings of the kind:
+// gcc:
+//    warning: value computed is not used
+//    warning: comparison between signed and unsigned integer expressions
+// msvc:
+//    warning C4018: '<' : signed/unsigned mismatch
+//    warning C4244: '+=' : conversion from 'double' to 'char', possible loss of data
+//    warning C4547: '*' : operator before comma has no effect; expected operator with side-effect
+//    warning C4800: 'int' : forcing value to bool 'true' or 'false' (performance warning)
+//    warning C4804: '<' : unsafe use of type 'bool' in operation
+//    warning C4805: '==' : unsafe mix of type 'bool' and type 'char' in operation
+// cannot find another implementation -> declared as system header to suppress these warnings.
+#if defined(__GNUC__)
+#   pragma GCC system_header
+#elif defined(BOOST_MSVC)
+#   pragma warning ( push )
+#   pragma warning ( disable : 4018 4244 4547 4800 4804 4805 4913 4133)
+#   if BOOST_WORKAROUND(BOOST_MSVC_FULL_VER, >= 140050000)
+#       pragma warning ( disable : 6334)
+#   endif
+#endif
+
+#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1900)
+
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/type_traits/make_void.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/is_void.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <boost/type_traits/remove_pointer.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <utility>
+
+namespace boost
+{
+
+   namespace binary_op_detail {
+
+      struct dont_care;
+
+      template <class T, class U, class Ret, class = boost::void_t<>>
+      struct has_minus_ret_imp : public boost::false_type {};
+
+      template <class T, class U, class Ret>
+      struct has_minus_ret_imp<T, U, Ret, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() - std::declval<typename add_reference<U>::type>())> >
+         : public boost::integral_constant<bool, ::boost::is_convertible<decltype(std::declval<typename add_reference<T>::type>() - std::declval<typename add_reference<U>::type>()), Ret>::value> {};
+
+      template <class T, class U, class = boost::void_t<> >
+      struct has_minus_void_imp : public boost::false_type {};
+
+      template <class T, class U>
+      struct has_minus_void_imp<T, U, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() - std::declval<typename add_reference<U>::type>())> >
+         : public boost::integral_constant<bool, ::boost::is_void<decltype(std::declval<typename add_reference<T>::type>() - std::declval<typename add_reference<U>::type>())>::value> {};
+
+      template <class T, class U, class = boost::void_t<>>
+      struct has_minus_dc_imp : public boost::false_type {};
+
+      template <class T, class U>
+      struct has_minus_dc_imp<T, U, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() - std::declval<typename add_reference<U>::type>())> >
+         : public boost::true_type {};
+
+      template <class T, class U, class Ret>
+      struct has_minus_ret_filter : public boost::binary_op_detail::has_minus_ret_imp <T, U, Ret> {};
+      template <class T, class U>
+      struct has_minus_ret_filter<T, U, void> : public boost::binary_op_detail::has_minus_void_imp <T, U> {};
+      template <class T, class U>
+      struct has_minus_ret_filter<T, U, boost::binary_op_detail::dont_care> : public boost::binary_op_detail::has_minus_dc_imp <T, U> {};
+
+      template <class T, class U, class Ret, bool b>
+      struct has_minus_void_ptr_filter : public boost::binary_op_detail::has_minus_ret_filter <T, U, Ret> {};
+      template <class T, class U, class Ret>
+      struct has_minus_void_ptr_filter<T, U, Ret, true> : public boost::false_type {};
+
+   }
+
+   template <class T, class U = T, class Ret = boost::binary_op_detail::dont_care>
+   struct has_minus : 
+      public boost::binary_op_detail::has_minus_void_ptr_filter<
+         T, U, Ret, 
+         boost::is_void<typename remove_pointer<typename remove_reference<T>::type>::type>::value 
+         || boost::is_void<typename remove_pointer<typename remove_reference<U>::type>::type>::value> {};
+
+
+}
+
+#else
+
+
 #define BOOST_TT_TRAIT_NAME has_minus
 #define BOOST_TT_TRAIT_OP -
 #define BOOST_TT_FORBIDDEN_IF\
@@ -50,6 +141,7 @@
       )\
       )
 
+#define BOOST_TT_FORBIDDEN_IF_NEW (boost::is_void<typename remove_pointer<typename boost::remove_reference<T>::type>::type>::value || boost::is_void<typename remove_pointer<typename boost::remove_reference<U>::type>::type>::value)
 
 #include <boost/type_traits/detail/has_binary_operator.hpp>
 
@@ -58,3 +150,4 @@
 #undef BOOST_TT_FORBIDDEN_IF
 
 #endif
+#endif
diff --git a/include/boost/type_traits/has_minus_assign.hpp b/include/boost/type_traits/has_minus_assign.hpp
index b53474e..2f89163 100644
--- a/include/boost/type_traits/has_minus_assign.hpp
+++ b/include/boost/type_traits/has_minus_assign.hpp
@@ -6,8 +6,98 @@
 //
 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
 
-#ifndef BOOST_TT_HAS_MINUS_ASSIGN_HPP_INCLUDED
-#define BOOST_TT_HAS_MINUS_ASSIGN_HPP_INCLUDED
+#ifndef BOOST_TT_has_minus_assign_ASSIGN_HPP_INCLUDED
+#define BOOST_TT_has_minus_assign_ASSIGN_HPP_INCLUDED
+
+#include <boost/config.hpp>
+#include <boost/config/workaround.hpp>
+
+// cannot include this header without getting warnings of the kind:
+// gcc:
+//    warning: value computed is not used
+//    warning: comparison between signed and unsigned integer expressions
+// msvc:
+//    warning C4018: '<' : signed/unsigned mismatch
+//    warning C4244: '+=' : conversion from 'double' to 'char', possible loss of data
+//    warning C4547: '*' : operator before comma has no effect; expected operator with side-effect
+//    warning C4800: 'int' : forcing value to bool 'true' or 'false' (performance warning)
+//    warning C4804: '<' : unsafe use of type 'bool' in operation
+//    warning C4805: '==' : unsafe mix of type 'bool' and type 'char' in operation
+// cannot find another implementation -> declared as system header to suppress these warnings.
+#if defined(__GNUC__)
+#   pragma GCC system_header
+#elif defined(BOOST_MSVC)
+#   pragma warning ( push )
+#   pragma warning ( disable : 4018 4244 4547 4800 4804 4805 4913 4133)
+#   if BOOST_WORKAROUND(BOOST_MSVC_FULL_VER, >= 140050000)
+#       pragma warning ( disable : 6334)
+#   endif
+#endif
+
+#if !defined(BOOST_NO_SFINAE_EXPR) && !defined(BOOST_NO_CXX11_DECLTYPE) && !BOOST_WORKAROUND(BOOST_MSVC, < 1900)
+
+#include <boost/type_traits/integral_constant.hpp>
+#include <boost/type_traits/make_void.hpp>
+#include <boost/type_traits/is_convertible.hpp>
+#include <boost/type_traits/is_void.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <boost/type_traits/remove_pointer.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <utility>
+
+namespace boost
+{
+
+   namespace binary_op_detail {
+
+      struct dont_care;
+
+      template <class T, class U, class Ret, class = boost::void_t<>>
+      struct has_minus_assign_ret_imp : public boost::false_type {};
+
+      template <class T, class U, class Ret>
+      struct has_minus_assign_ret_imp<T, U, Ret, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() -= std::declval<typename add_reference<U>::type>())> >
+         : public boost::integral_constant<bool, ::boost::is_convertible<decltype(std::declval<typename add_reference<T>::type>() -= std::declval<typename add_reference<U>::type>()), Ret>::value> {};
+
+      template <class T, class U, class = boost::void_t<> >
+      struct has_minus_assign_void_imp : public boost::false_type {};
+
+      template <class T, class U>
+      struct has_minus_assign_void_imp<T, U, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() -= std::declval<typename add_reference<U>::type>())> >
+         : public boost::integral_constant<bool, ::boost::is_void<decltype(std::declval<typename add_reference<T>::type>() -= std::declval<typename add_reference<U>::type>())>::value> {};
+
+      template <class T, class U, class = boost::void_t<>>
+      struct has_minus_assign_dc_imp : public boost::false_type {};
+
+      template <class T, class U>
+      struct has_minus_assign_dc_imp<T, U, boost::void_t<decltype(std::declval<typename add_reference<T>::type>() -= std::declval<typename add_reference<U>::type>())> >
+         : public boost::true_type {};
+
+      template <class T, class U, class Ret>
+      struct has_minus_assign_ret_filter : public boost::binary_op_detail::has_minus_assign_ret_imp <T, U, Ret> {};
+      template <class T, class U>
+      struct has_minus_assign_ret_filter<T, U, void> : public boost::binary_op_detail::has_minus_assign_void_imp <T, U> {};
+      template <class T, class U>
+      struct has_minus_assign_ret_filter<T, U, boost::binary_op_detail::dont_care> : public boost::binary_op_detail::has_minus_assign_dc_imp <T, U> {};
+
+      template <class T, class U, class Ret, bool b>
+      struct has_minus_assign_void_ptr_filter : public boost::binary_op_detail::has_minus_assign_ret_filter <T, U, Ret> {};
+      template <class T, class U, class Ret>
+      struct has_minus_assign_void_ptr_filter<T, U, Ret, true> : public boost::false_type {};
+
+   }
+
+   template <class T, class U = T, class Ret = boost::binary_op_detail::dont_care>
+   struct has_minus_assign :
+      public boost::binary_op_detail::has_minus_assign_void_ptr_filter<
+      T, U, Ret,
+      boost::is_void<typename remove_pointer<typename remove_reference<T>::type>::type>::value
+      || boost::is_void<typename remove_pointer<typename remove_reference<U>::type>::type>::value> {};
+
+
+}
+
+#else
 
 #define BOOST_TT_TRAIT_NAME has_minus_assign
 #define BOOST_TT_TRAIT_OP -=
@@ -63,3 +153,4 @@
 #undef BOOST_TT_FORBIDDEN_IF
 
 #endif
+#endif