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<title>Issue 4341: Missing rvalue reference qualification for task::connect()</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#New">New</a> status.</em></p>
<h3 id="4341"><a href="lwg-active.html#4341">4341</a>. Missing rvalue reference qualification for <code>task::connect()</code></h3>
<p><b>Section:</b> 33.13.6.2 <a href="https://wg21.link/task.class">[task.class]</a> <b>Status:</b> <a href="lwg-active.html#New">New</a>
 <b>Submitter:</b> Dietmar Kühl <b>Opened:</b> 2025-08-31 <b>Last modified:</b> 2025-09-01</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#task.class">active issues</a> in [task.class].</p>
<p><b>View all other</b> <a href="lwg-index.html#task.class">issues</a> in [task.class].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<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>


<p id="res-4341"><b>Proposed resolution:</b></p>
<p>
In the synopsis in 33.13.6.2 <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 33.13.6.3 <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>





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