LWG-3170 is_always_equal added to std::allocator makes the standard library treat derived types as always equal

[StephanTLavavej]

LWG-3170 is_always_equal added to std::allocator makes the standard library treat derived types as always equal

[futuarmo]

using is_always_equal = true_type; now presents in _Default_allocator_traits, so according to this part of LWG:

Add a new subclause in Annex D after D.13 [depr.str.strstreams]:

D.? The default allocator [depr.default.allocator]

-?- The following member is defined in addition to those specified in 20.10.10 [default.allocator]:

namespace std {
  template <class T> class allocator {
  public:
    using is_always_equal = true_type;
  };
}

we should just mark is_always_equal member of std::allocator as deprecated, am I right?