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<title>Issue 3675: std::ios_base::iword/pword might be misspecified</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#New">New</a> status.</em></p>
<h3 id="3675"><a href="lwg-active.html#3675">3675</a>. <code>std::ios_base::iword/pword</code> might be misspecified</h3>
<p><b>Section:</b> 31.5.2.6 <a href="https://wg21.link/ios.base.storage">[ios.base.storage]</a> <b>Status:</b> <a href="lwg-active.html#New">New</a>
 <b>Submitter:</b> Jiang An <b>Opened:</b> 2022-02-14 <b>Last modified:</b> 2022-03-04</p>
<p><b>Priority: </b>4
</p>
<p><b>View all other</b> <a href="lwg-index.html#ios.base.storage">issues</a> in [ios.base.storage].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Currently 31.5.2.6 <a href="https://wg21.link/ios.base.storage">[ios.base.storage]</a> p5 and p8 say "On failure, a valid <code>long&amp;/void*&amp;</code> 
initialized to <code>0</code>". Such wording seems wrong, because a <code>long&amp;/void*&amp;</code> variable or 
return value can't be initialized with <code>0</code>. And the values of referenced objects may be underspecified, 
because an implementation may reuse the same <code>long/void*</code> objects on failure, and thus it's insufficient 
to specify the initial values of these objects only.
</p>

<p><i>[2022-03-04; Reflector poll]</i></p>

<p>
Set priority to 4 after reflector poll.
</p>



<p id="res-3675"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/N4901" title=" Working Draft, Standard for Programming Language C++">N4901</a>.
</p>

<ol>
<li><p>Modify 31.5.2.6 <a href="https://wg21.link/ios.base.storage">[ios.base.storage]</a> as indicated:</p>

<blockquote>
<pre>
long&amp; iword(int idx);
</pre>
<blockquote>
<p>
-3- [&hellip;]
<p/>
-4- [&hellip;]
<p/>
-5- <i>Returns:</i> On success <code>iarray[idx]</code>. On failure, a<ins>n</ins> <del>valid</del> <ins>lvalue of type</ins> 
<code>long<del>&amp;</del></code> <ins>with value <code>0L</code></ins><del>initialized to <code>0</code></del>.
</p>
</blockquote>
<pre>
void*&amp; pword(int idx);
</pre>
<blockquote>
<p>
-6- [&hellip;]
<p/>
-7- [&hellip;]
<p/>
-8- <i>Returns:</i> On success <code>parray[idx]</code>. On failure<ins>,</ins> a<ins>n</ins> <del>valid</del> 
<ins>lvalue of type</ins> <code>void*<del>&amp;</del></code> <ins>with a null pointer value</ins><del>initialized 
to <code>0</code></del>.
<p/>
-9- <i>Remarks:</i> After a subsequent call to <code>pword(int)</code> for the same object, the earlier return value may no
longer be valid.
</p>
</blockquote>
</blockquote>
</li>
</ol>





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