Avoid allocator::pointer removed in C++20 in Boost

diff --git a/bundled/boost-1.70.0/include/boost/signals2/detail/auto_buffer.hpp b/bundled/boost-1.70.0/include/boost/signals2/detail/auto_buffer.hpp
index 5ff8dd2c630ed2a003a74b4bbf9ec24b4f0d6b23..5f2664a8abb50662241dcb3783e88ab20acf1638 100644 (file)
--- a/bundled/boost-1.70.0/include/boost/signals2/detail/auto_buffer.hpp
+++ b/bundled/boost-1.70.0/include/boost/signals2/detail/auto_buffer.hpp
@@ -142,7 +142,11 @@ namespace detail
         typedef typename Allocator::size_type            size_type;
         typedef typename Allocator::difference_type      difference_type;
         typedef T*                                       pointer;
+#ifdef BOOST_NO_CXX11_ALLOCATOR
         typedef typename Allocator::pointer              allocator_pointer;
+#else
+        typedef typename std::allocator_traits<Allocator>::pointer allocator_pointer;
+#endif
         typedef const T*                                 const_pointer;
         typedef T&                                       reference;
         typedef const T&                                 const_reference;