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<title>Issue 3510: Customization point objects should be invocable as non-const too</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#Resolved">Resolved</a> status.</em></p>
<h3 id="3510"><a href="lwg-defects.html#3510">3510</a>. Customization point objects should be invocable as non-<code>const</code> too</h3>
<p><b>Section:</b> 16.3.3.3.5 <a href="https://wg21.link/customization.point.object">[customization.point.object]</a> <b>Status:</b> <a href="lwg-active.html#Resolved">Resolved</a>
 <b>Submitter:</b> Tim Song <b>Opened:</b> 2020-12-15 <b>Last modified:</b> 2021-06-14</p>
<p><b>Priority: </b>3
</p>
<p><b>View all other</b> <a href="lwg-index.html#customization.point.object">issues</a> in [customization.point.object].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#Resolved">Resolved</a> status.</p>
<p><b>Discussion:</b></p>
<p>
16.3.3.3.5 <a href="https://wg21.link/customization.point.object">[customization.point.object]</a> promises that customization point objects
are semiregular and that all copies are equal, which permits copies to
be freely made. In C++, making copies tends to drop <i>cv</i>-qualification,
but there does not appear to be anything that guarantees that you can
invoke these objects as non-<code>const</code> (or as rvalues, for that matter).
<p/>
It is possible that the use of <code>invocable&lt;const F&amp;, Args...&gt;</code> here was
meant to bring in implicit expression variations, but <a href="https://wg21.link/p2102r0">P2102R0</a> 
has since clarified that this formulation doesn't do that.
</p>

<p><i>[2021-01-15; Telecon prioritization]</i></p>

<p>
Set priority to 3 following reflector and telecon discussions.
</p>

<p><i>[2021-06-13 Resolved by the adoption of <a href="https://wg21.link/P2281R1" title=" Clarifying range adaptor objects">P2281R1</a> at the June 2021 plenary. Status changed: New &rarr; Resolved.]</i></p>



<p id="res-3510"><b>Proposed resolution:</b></p>





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