Fixes #312

Author: igaztanaga

doc/container.qbk

@@ -1455,6 +1455,7 @@ use [*Boost.Container]? There are several reasons for that:
    * [@https://github.com/boostorg/container/issues/309 GitHub #309: ['"Performance regression of boost::container::static_vector introduced in boost v1.86"]].
    * [@https://github.com/boostorg/container/issues/306 GitHub #306: ['"new_allocator.hpp error: '__cpp_sized_deallocation' is not defined, evaluates to 0 [-Werror,-Wundef]"]].
    * [@https://github.com/boostorg/container/issues/310 GitHub #310: ['"flat_map: Mention correct type in documentation of emplace and emplace_hint"]].
+   * [@https://github.com/boostorg/container/issues/312 GitHub #312: ['"flat_map std::allocator::is_always_equal is deprecated"]].
    * [@https://github.com/boostorg/container/pull/317/ GitHub #317: ['"Partial revert of changes for Issue #209 - compiler warnings"]].
 
 [endsect]

include/boost/container/allocator_traits.hpp

@@ -227,6 +227,11 @@ template<class Allocator>
 struct is_not_std_allocator
 {  BOOST_STATIC_CONSTEXPR bool value = !is_std_allocator<Allocator>::value; };
 
+#if defined(BOOST_CONTAINER_GCC_COMPATIBLE_HAS_DIAGNOSTIC_IGNORED)
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+#endif
+
 BOOST_INTRUSIVE_INSTANTIATE_DEFAULT_TYPE_TMPLT(pointer)
 BOOST_INTRUSIVE_INSTANTIATE_EVAL_DEFAULT_TYPE_TMPLT(const_pointer)
 BOOST_INTRUSIVE_INSTANTIATE_DEFAULT_TYPE_TMPLT(reference)
@@ -241,6 +246,10 @@ BOOST_INTRUSIVE_INSTANTIATE_DEFAULT_TYPE_TMPLT(is_always_equal)
 BOOST_INTRUSIVE_INSTANTIATE_DEFAULT_TYPE_TMPLT(difference_type)
 BOOST_INTRUSIVE_INSTANTIATE_DEFAULT_TYPE_TMPLT(is_partially_propagable)
 
+#if defined(BOOST_CONTAINER_GCC_COMPATIBLE_HAS_DIAGNOSTIC_IGNORED)
+#pragma GCC diagnostic pop
+#endif
+
 }  //namespace dtl {
 
 #endif   //#ifndef BOOST_CONTAINER_DOXYGEN_INVOKED