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<title>Issue 2726: [recursive_]directory_iterator::increment(error_code&amp;) is underspecified</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++17">C++17</a> status.</em></p>
<h3 id="2726"><a href="lwg-defects.html#2726">2726</a>. <code>[recursive_]directory_iterator::increment(error_code&amp;)</code> is underspecified</h3>
<p><b>Section:</b> 31.12.11.2 <a href="https://wg21.link/fs.dir.itr.members">[fs.dir.itr.members]</a>, 31.12.12.2 <a href="https://wg21.link/fs.rec.dir.itr.members">[fs.rec.dir.itr.members]</a> <b>Status:</b> <a href="lwg-active.html#C++17">C++17</a>
 <b>Submitter:</b> Daniel Kr&uuml;gler <b>Opened:</b> 2016-06-20 <b>Last modified:</b> 2017-07-30</p>
<p><b>Priority: </b>0
</p>
<p><b>View all other</b> <a href="lwg-index.html#fs.dir.itr.members">issues</a> in [fs.dir.itr.members].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++17">C++17</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Setting <code>X</code> as being either <code>directory_iterator</code> or <code>recursive_directory_iterator</code> there exists a member function
in <code>X</code>,
</p>
<blockquote>
<pre>
X&amp; increment(error_code&amp; ec) noexcept;
</pre>
</blockquote>
<p>
whose effects are described as:
</p>
<blockquote><p>
As specified by Input iterators (24.2.3).
</p></blockquote>
<p>
which is somewhat surprising, because for input iterators there is no call expression naming <code>increment</code> specified.
<p/>
The intention here is to consider <code>increment</code> as a another name for the prefix increment operator of iterators, but that 
needs to be expressed somewhere.
</p>
<p><i>[2016-06 Oulu]</i></p>

<p>Moved to P0/Ready during issues prioritization.</p>
<p>Friday: status to Immediate</p>


<p id="res-2726"><b>Proposed resolution:</b></p>
<p>This wording is relative to N4594.</p>
<p>
<blockquote class="note">
<p>
[<i>Drafting note:</i> The suggested wording for this issue also repairs the information loss that had been caused by the
third bullet of the proposed resolution of <a href="lwg-defects.html#2704" title="recursive_directory_iterator's members should require '*this is dereferenceable' (Status: C++17)">2704</a><sup><a href="https://cplusplus.github.io/LWG/issue2704" title="Latest snapshot">(i)</a></sup>]
</p>
</blockquote>
</p>
<ol>
<li><p>Change 31.12.11.2 <a href="https://wg21.link/fs.dir.itr.members">[fs.dir.itr.members]</a> as indicated:</p>

<blockquote>
<pre>
directory_iterator&amp; operator++();
directory_iterator&amp; increment(error_code&amp; ec) noexcept;
</pre>
<blockquote>
<p>
-10- <i>Effects:</i> As specified <del>by</del> <ins>for the prefix increment operation of</ins> Input 
iterators (24.3.5.3 <a href="https://wg21.link/input.iterators">[input.iterators]</a>).
</p>
</blockquote>
</blockquote>
</li>

<li><p>Change 31.12.12.2 <a href="https://wg21.link/fs.rec.dir.itr.members">[fs.rec.dir.itr.members]</a> as indicated:</p>

<blockquote>
<pre>
recursive_directory_iterator&amp; operator++();
recursive_directory_iterator&amp; increment(error_code&amp; ec) noexcept;
</pre>
<blockquote>
<p>
[&hellip;]
<p/>
-27- <i>Effects:</i> As specified <del>by</del> <ins>for the prefix increment operation of</ins> Input iterators 
(24.3.5.3 <a href="https://wg21.link/input.iterators">[input.iterators]</a>), except that: [&hellip;]
</p>
</blockquote>
</blockquote>
</li>
</ol>





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