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51 changes: 51 additions & 0 deletions xml/issue4341.xml
Original file line number Diff line number Diff line change
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<?xml version='1.0' encoding='utf-8' standalone='no'?>
<!DOCTYPE issue SYSTEM "lwg-issue.dtd">

<issue num="4341" status="New">
<title>>Missing rvalue reference qualification for <code>task::connect()</code></title>
<section><sref ref="[task.class]"/></section>
<submitter>Dietmar Kühl</submitter>
<date>31 Aug 2025</date>
<priority>99</priority>

<discussion>
<p>
Coroutines can't be copied. Thus, a <code>task</code> can be
<code>connect()</code> just once. To represent that
<code>task::connect()</code> should be rvalue reference qualified
but currently it isn't.
</p>
</discussion>

<resolution>
<p>
In the synopsis in <a href="https://wg21.link/task.class">[task.class]</a> add rvalue
reference qualification to <code>task::connect()</code>:
<blockquote><pre>
namespace std::execution {
template&lt;class T, class Environment&gt;
class task {
...
template&lt;receiver Rcvr&gt;
<i>state</i>&lt;Rcvr&gt; connect(Rcvr&amp;&amp; rcvr) <ins>&amp;&amp;</ins>;
...
}
}
</pre></blockquote>
</p>
<p>
In the specification in <a href="https://wg21.link/task.members">[task.members]</a> paragraph 3 add rvalue
reference qualification to <code>task::connect()</code>:
<blockquote>
<pre>
template&lt;receiver Rcvr&gt;
<i>state</i>&lt;Rcvr&gt; connect(Rcvr&amp;&amp; rcvr) <ins>&amp;&amp;</ins>;
</pre>
<p>-3- <i>Precondition</i>: <code>bool(handle)</code> is <code>true</code>.</p>
<p>-4- <i>Effects</i>: Equivalent to:</p>
<pre> return state&lt;Rcvr&gt;(exchange(handle, {}), std::forward&lt;Rcvr&gt;(recv));</pre>
</blockquote>
</p>
</resolution>

</issue>