Fix using signals2 with gcc 10 and --std=gnu++20: deprecated std::allocator member access.

Romain-Geissler-1A · Romain-Geissler-1A · commit 15fcf2135637 · 2020-03-09T16:53:04.000Z
diff --git a/include/boost/signals2/detail/auto_buffer.hpp b/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;
