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<title>Issue 3434: ios_base never reclaims memory for iarray and parray</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++23">C++23</a> status.</em></p>
<h3 id="3434"><a href="lwg-defects.html#3434">3434</a>. <code>ios_base</code> never reclaims memory for <code>iarray</code> and <code>parray</code></h3>
<p><b>Section:</b> 31.5.2.8 <a href="https://wg21.link/ios.base.cons">[ios.base.cons]</a> <b>Status:</b> <a href="lwg-active.html#C++23">C++23</a>
 <b>Submitter:</b> Alisdair Meredith <b>Opened:</b> 2020-04-26 <b>Last modified:</b> 2023-11-22</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all other</b> <a href="lwg-index.html#ios.base.cons">issues</a> in [ios.base.cons].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#C++23">C++23</a> status.</p>
<p><b>Discussion:</b></p>
<p>
According to 31.5.2.6 <a href="https://wg21.link/ios.base.storage">[ios.base.storage]</a> the class <code>ios_base</code> allocates memory,
represented by two exposition-only pointers, <code>iarray</code> and <code>parray</code> in response
to calls to <code>iword</code> and <code>pword</code>. However, the specification for the destructor
in 31.5.2.8 <a href="https://wg21.link/ios.base.cons">[ios.base.cons]</a> says nothing about reclaiming any allocated memory.
</p>

<p><i>[2020-07-17; Reflector prioritization]</i></p>

<p>
Set priority to 0 and status to Tentatively Ready after six votes in favour during reflector discussions.
</p>
<p><i>[2020-11-09 Approved In November virtual meeting. Status changed: Tentatively Ready &rarr; WP.]</i></p>



<p id="res-3434"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/n4861">N4861</a>.
</p>

<ol>
<li><p>Modify 31.5.2.8 <a href="https://wg21.link/ios.base.cons">[ios.base.cons]</a> as indicated:</p>

<blockquote class="note">
<p>
[<i>Drafting note:</i> Wording modeled on container requirements]
</p>
</blockquote>

<blockquote>
<pre>
~ios_base();
</pre>
<blockquote>
<p>
-2- <i>Effects:</i> Calls each registered callback pair <code>(fn, idx)</code> 
(31.5.2.7 <a href="https://wg21.link/ios.base.callback">[ios.base.callback]</a>) as <code>(*fn)(erase_event, *this, idx)</code> 
at such time that any <code>ios_base</code> member function called from within 
<code>fn</code> has well-defined results. <ins>Then, any memory obtained is deallocated.</ins>
</p>
</blockquote>
</blockquote>
</li>
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