Add compile-time check to make sure allocator_type::value_type and container's value_type are the same type.

include/boost/container/devector.hpp

@@ -173,6 +173,11 @@ class devector
 
    #ifndef BOOST_CONTAINER_DOXYGEN_INVOKED
    private:
+
+   //`allocator_type::value_type` must match container's `value type`. If this
+   //assertion fails, please review your allocator definition. 
+   BOOST_CONTAINER_STATIC_ASSERT((dtl::is_same<value_type, typename allocator_traits<allocator_type>::value_type>::value));
+
    BOOST_COPYABLE_AND_MOVABLE(devector)
 
    // Guard to deallocate buffer on exception