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<title>Issue 2971: variant should require Destructible types</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#NAD">NAD</a> status.</em></p>
<h3 id="2971"><a href="lwg-closed.html#2971">2971</a>. <code>variant</code> should require <code>Destructible</code> types</h3>
<p><b>Section:</b> 22.6.3 <a href="https://wg21.link/variant.variant">[variant.variant]</a> <b>Status:</b> <a href="lwg-active.html#NAD">NAD</a>
 <b>Submitter:</b> Agust&iacute;n K-ballo Berg&eacute; <b>Opened:</b> 2017-05-31 <b>Last modified:</b> 2020-09-06</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#variant.variant">issues</a> in [variant.variant].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#NAD">NAD</a> status.</p>
<p><b>Discussion:</b></p>
<p>
The state of a <code>variant</code> is not specified if an exception is thrown during
the destruction of the active alternative. Exceptions should not be
allowed to escape during destruction of an object used as a <code>variant</code>
alternative. Otherwise, it should be specified that the <code>variant</code> object
might not hold a value.
</p>

<p><i>[2017-07 Toronto Monday issue prioritization]</i></p>

<p>NAD; [res.on.functions]/2 already gives us this guarantee.</p>


<p id="res-2971"><b>Proposed resolution:</b></p>
<p>This wording is relative to <a href="https://wg21.link/n4659">N4659</a>.</p>

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<p>Edit 22.6.3 <a href="https://wg21.link/variant.variant">[variant.variant]</a> as indicated:</p>

<blockquote>
<p>
-2- All types in <code>Types...</code> shall be (possibly cv-qualified) object types that are not arrays<ins>, and 
shall satisfy the requirements of <code>Destructible</code> (Table 27)</ins>.
</p>
</blockquote>
</li>
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