From fb4430512d26681a7b06c434c793f98567a8ad4a Mon Sep 17 00:00:00 2001
From: John Maddock <john@johnmaddock.co.uk>
Date: Fri, 9 Feb 2018 18:20:23 +0000
Subject: [PATCH] Fix up -= and += detection for clang.

---
 .../boost/type_traits/has_minus_assign.hpp    |  4 +-
 include/boost/type_traits/has_plus_assign.hpp | 90 +++++++++++++++++++
 2 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/include/boost/type_traits/has_minus_assign.hpp b/include/boost/type_traits/has_minus_assign.hpp
index fcca10e..0ae6720 100644
--- a/include/boost/type_traits/has_minus_assign.hpp
+++ b/include/boost/type_traits/has_minus_assign.hpp
@@ -40,6 +40,7 @@
 #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/is_pointer.hpp>
 #include <boost/type_traits/add_reference.hpp>
 #include <boost/type_traits/remove_pointer.hpp>
 #include <boost/type_traits/remove_reference.hpp>
@@ -92,7 +93,8 @@ namespace boost
       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> {};
+      || boost::is_void<typename remove_pointer<typename remove_reference<U>::type>::type>::value
+      || (boost::is_pointer<typename remove_reference<T>::type>::value && boost::is_pointer<typename remove_reference<U>::type>::value)> {};
 
 
 }
diff --git a/include/boost/type_traits/has_plus_assign.hpp b/include/boost/type_traits/has_plus_assign.hpp
index 5ef6f23..faeb220 100644
--- a/include/boost/type_traits/has_plus_assign.hpp
+++ b/include/boost/type_traits/has_plus_assign.hpp
@@ -9,6 +9,95 @@
 #ifndef BOOST_TT_HAS_PLUS_ASSIGN_HPP_INCLUDED
 #define BOOST_TT_HAS_PLUS_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) && !BOOST_WORKAROUND(BOOST_GCC, < 40900)
+
+#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/is_same.hpp>
+#include <boost/type_traits/is_pointer.hpp>
+#include <boost/type_traits/is_arithmetic.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <boost/type_traits/remove_pointer.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <boost/type_traits/remove_cv.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_plus_assign_ret_imp : public boost::false_type {};
+
+      template <class T, class U, class Ret>
+      struct has_plus_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_plus_assign_void_imp : public boost::false_type {};
+
+      template <class T, class U>
+      struct has_plus_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_plus_assign_dc_imp : public boost::false_type {};
+
+      template <class T, class U>
+      struct has_plus_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_plus_assign_filter_ret : public boost::binary_op_detail:: has_plus_assign_ret_imp <T, U, Ret> {};
+      template <class T, class U>
+      struct has_plus_assign_filter_ret<T, U, void> : public boost::binary_op_detail:: has_plus_assign_void_imp <T, U> {};
+      template <class T, class U>
+      struct has_plus_assign_filter_ret<T, U, boost::binary_op_detail::dont_care> : public boost::binary_op_detail:: has_plus_assign_dc_imp <T, U> {};
+
+      template <class T, class U, class Ret, bool f>
+      struct has_plus_assign_filter_impossible : public boost::binary_op_detail:: has_plus_assign_filter_ret <T, U, Ret> {};
+      template <class T, class U, class Ret>
+      struct has_plus_assign_filter_impossible<T, U, Ret, true> : public boost::false_type {};
+
+   }
+
+   template <class T, class U = T, class Ret = boost::binary_op_detail::dont_care>
+   struct has_plus_assign : public boost::binary_op_detail:: has_plus_assign_filter_impossible <T, U, Ret, boost::is_arithmetic<typename boost::remove_reference<T>::type>::value && boost::is_pointer<typename remove_reference<U>::type>::value && !boost::is_same<bool, typename boost::remove_cv<typename remove_reference<T>::type>::type>::value> {};
+
+}
+
+#else
+
 #define BOOST_TT_TRAIT_NAME has_plus_assign
 #define BOOST_TT_TRAIT_OP +=
 #define BOOST_TT_FORBIDDEN_IF\
@@ -64,3 +153,4 @@
 #undef BOOST_TT_FORBIDDEN_IF
 
 #endif
+#endif