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<title>Issue 3887: Version macro for allocate_at_least</title>
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<p><em>This page is a snapshot from the LWG issues list, see the <a href="lwg-active.html">Library Active Issues List</a> for more information and the meaning of <a href="lwg-active.html#WP">WP</a> status.</em></p>
<h3 id="3887"><a href="lwg-defects.html#3887">3887</a>. Version macro for <code>allocate_at_least</code></h3>
<p><b>Section:</b> 17.3.2 <a href="https://wg21.link/version.syn">[version.syn]</a> <b>Status:</b> <a href="lwg-active.html#WP">WP</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2023-02-14 <b>Last modified:</b> 2023-11-22</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#version.syn">active issues</a> in [version.syn].</p>
<p><b>View all other</b> <a href="lwg-index.html#version.syn">issues</a> in [version.syn].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#WP">WP</a> status.</p>
<p><b>Discussion:</b></p>
<p>
In Issaquah, we just adopted <a href="https://wg21.link/P2652R0" title=" Disallow user specialization of allocator_traits">P2652R0</a>, forbidding user specialization of <code>allocator_traits</code>. 
<p/>
It looks like we did not deem that worthy of a feature macro.
<p/>
However, it also changed the interface of the C++23 addition, <code>allocate_at_least</code>, which is covered by the macro 
<code>__cpp_lib_allocate_at_least</code>.
<p/>
I believe we should have updated that macro for this significant change in how that function is accessed 
(from free function to a member of <code>allocator_traits</code>). Unfortunately, there are no more meetings 
to process a comment to that effect, and I suspect this rises beyond the purview of an editorial change, 
although I live in hope (as the original paper left the value of the macro to the editor, although we 
approved existing working papers where that macro does have a value, i.e., status quo).
</p>

<p><i>[2023-03-22; Reflector poll]</i></p>

<p>
Set status to Tentatively Ready after seven votes in favour during reflector poll.
But "if we don’t get the editors to do it for C++23 there doesn’t seem to be
any point doing it."
</p>

<p><i>[2023-06-17 Approved at June 2023 meeting in Varna. Status changed: Voting &rarr; WP.]</i></p>



<p id="res-3887"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/N4928" title=" Working Draft, Standard for Programming Language C++">N4928</a>.
</p>

<ol>
<li><p>Modify 17.3.2 <a href="https://wg21.link/version.syn">[version.syn]</a>, header <code>&lt;version&gt;</code> synopsis, as indicated and replace
the placeholder <code>YYYYMM</code> by the year and month of adoption of <a href="https://wg21.link/P2652R0" title=" Disallow user specialization of allocator_traits">P2652R0</a>:</p>

<blockquote>
<pre>
[&hellip;]
#define __cpp_lib_algorithm_iterator_requirements  202207L
  // <i>also in &lt;algorithm&gt;, &lt;numeric&gt;, &lt;memory&gt;</i>
#define __cpp_lib_allocate_at_least                <del>202106</del><ins>YYYYMM</ins>L // <i>also in &lt;memory&gt;</i>
#define __cpp_lib_allocator_traits_is_always_equal 201411L
  // <i>also in [&hellip;]</i>
[&hellip;]
</pre>
</blockquote>

</li>

</ol>





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