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<title>Issue 1379: pair copy-assignment not consistent for references</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="1379"><a href="lwg-defects.html#1379">1379</a>. <code>pair</code> copy-assignment not consistent for references</h3>
<p><b>Section:</b> 22.3.2 <a href="https://wg21.link/pairs.pair">[pairs.pair]</a> <b>Status:</b> <a href="lwg-active.html#Resolved">Resolved</a>
 <b>Submitter:</b> INCITS <b>Opened:</b> 2010-08-25 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View other</b> <a href="lwg-index-open.html#pairs.pair">active issues</a> in [pairs.pair].</p>
<p><b>View all other</b> <a href="lwg-index.html#pairs.pair">issues</a> in [pairs.pair].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#Resolved">Resolved</a> status.</p>
<p><b>Discussion:</b></p>
<p><b>Addresses US-95</b></p>
<p>
Copy-assignment for <code>pair</code> is defaulted and does not work
for pairs with reference members. This is inconsistent with
conversion-assignment, which deliberately succeeds even
if one or both elements are reference types, just as for
<code>tuple</code>. The copy-assignment operator should be
consistent with the conversion-assignment operator and
with <code>tuple</code>'s assignment operators.
</p>

<p><i>[
2010-10-24 Daniel adds:
]</i></p>


<blockquote><p>
Accepting <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3140.html">n3140</a> would provide a superior resolution,
because <code>pair</code> does not depend on the semantic requirements of <code>CopyAssignable</code>.
</p></blockquote>

<p><i>[
2010-11 Batavia
]</i></p>

<p>
Resolved by adopting <a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3140.html">n3140</a>.
</p>



<p id="res-1379"><b>Proposed resolution:</b></p>
<p>Add to <code>pair</code> synopsis:</p>
<blockquote><p>
<code>pair&amp; operator=(const pair&amp; p);</code>
</p></blockquote>
<p>
Add before paragraph 9:
</p>
<blockquote><p>
<code>pair&amp; operator=(const pair&amp; p);</code>
</p><blockquote>
<p>
<i>Requires</i>: <code>T1</code> and <code>T2</code> shall satisfy the
requirements of <code>CopyAssignable</code>.
</p>
<p>
<i>Effects</i>: Assigns <code>p.first</code> to <code>first</code> and <code>p.second</code> to
<code>second</code>.
<i>Returns</i>: <code>*this</code>.
</p>
</blockquote>
</blockquote>





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