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<title>Issue 3309: Is &lt;ios&gt; implicitly #included by &lt;sstream&gt;, &lt;fstream&gt; etc.?</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="3309"><a href="lwg-active.html#3309">3309</a>. Is <code>&lt;ios&gt;</code> implicitly <code>#include</code>d by <code>&lt;sstream&gt;</code>, <code>&lt;fstream&gt;</code> etc.?</h3>
<p><b>Section:</b> 31.8 <a href="https://wg21.link/string.streams">[string.streams]</a>, 31.10 <a href="https://wg21.link/file.streams">[file.streams]</a> <b>Status:</b> <a href="lwg-active.html#New">New</a>
 <b>Submitter:</b> Jens Maurer <b>Opened:</b> 2019-11-01 <b>Last modified:</b> 2019-11-04</p>
<p><b>Priority: </b>3
</p>
<p><b>View all other</b> <a href="lwg-index.html#string.streams">issues</a> in [string.streams].</p>
<p><b>View all issues with</b> <a href="lwg-status.html#New">New</a> status.</p>
<p><b>Discussion:</b></p>
<p>
It is unclear whether the streams headers implicitly <code>#include &lt;ios&gt;</code> and make (for example) 
the name <code>std::basic_ios</code> available after including <code>&lt;sstream&gt;</code>.
<p/>
This question becomes more important as header units arrive with modules, where there is an explicit 
choice whether to re-export names from subordinate headers.
</p>

<p><i>[2019-11 Priority to 3 during Monday issue prioritization in Belfast]</i></p>



<p id="res-3309"><b>Proposed resolution:</b></p>




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