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<title>Issue 1021: Allow nullptr_t assignments to unique_ptr</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#C++11">C++11</a> status.</em></p>
<h3 id="1021"><a href="lwg-defects.html#1021">1021</a>. Allow <code>nullptr_t</code> assignments to <code>unique_ptr</code></h3>
<p><b>Section:</b> 20.3.1.3.4 <a href="https://wg21.link/unique.ptr.single.asgn">[unique.ptr.single.asgn]</a> <b>Status:</b> <a href="lwg-active.html#C++11">C++11</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2009-03-11 <b>Last modified:</b> 2016-01-28</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#unique.ptr.single.asgn">issues</a> in [unique.ptr.single.asgn].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++11">C++11</a> status.</p>
<p><b>Discussion:</b></p>

<p><b>Addresses UK 211 [CD1]</b></p>

<p>
The <code>nullptr_t</code> type was introduced to resolve the null pointer literal
problem. It should be used for the assignment operator, as with the
constructor and elsewhere through the library.
</p>

<p><i>[
Batavia (2009-05):
]</i></p>

<blockquote><p>
We agree with the proposed resolution.
Move to Tentatively Ready.
</p></blockquote>


<p id="res-1021"><b>Proposed resolution:</b></p>
<p>
Change the synopsis in 20.3.1.3 <a href="https://wg21.link/unique.ptr.single">[unique.ptr.single]</a>:
</p>

<blockquote><pre>
unique_ptr&amp; operator=(<del><i>unspecified-pointer-type</i></del> <ins>nullptr_t</ins>);
</pre></blockquote>

<p>
Change 20.3.1.3.4 <a href="https://wg21.link/unique.ptr.single.asgn">[unique.ptr.single.asgn]</a>:
</p>

<blockquote><pre>
unique_ptr&amp; operator=(<del><i>unspecified-pointer-type</i></del> <ins>nullptr_t</ins>);
</pre>
<blockquote><p>
<del>Assigns from the literal 0 or <code>NULL</code>. [<i>Note:</i> The
<i>unspecified-pointer-type</i> is often implemented as a pointer to a
private data member, avoiding many of the implicit conversion pitfalls.
&mdash; <i>end note</i>]</del>
</p></blockquote>
</blockquote>





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