Hello SG-featuretestmacros,

See the forwarded mail below. We didn't add a macro for P0591R4. Should we? Any objection to my proposed name?

---------- Forwarded message ---------
From: Jonathan Wakely <cxx@kayari.org>
Date: Thu, 22 Oct 2020 at 10:21
Subject: Re: [isocpp-lib] P0591R4 Utility functions to implement uses-allocator construction
To: Library Working Group <lib@lists.isocpp.org>

On Sat, 17 Nov 2018 at 23:53, Jonathan Wakely <cxx@kayari.org> wrote:

On Fri, 16 Nov 2018 at 22:03, Jens Maurer <Jens.Maurer@gmx.net> wrote:

Seems to be missing a feature-test macro, although it adds a couple of
functions to the standard library.

Is the omission intentional?

I don't believe so, I think we just overlooked it.
If not, let's have an LWG issue to add one in Kona.


Resurrecting an old thread, I don't think we ever added an issue about the missing feature test macro for P0591R4. Does anybody remember if we discussed it and decided it wasn't needed?

I'm going to define __cpp_lib_make_obj_using_allocator 201811L in libstdc++, because I want to use it in <scoped_allocator> and <memory_resource> to know when <memory> provides these new functions (without having to repeat the same preprocessor conditions that <memory> uses).