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<title>Issue 4247: Header &lt;stdbit.h&gt; is not yet freestanding</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#WP">WP</a> status.</em></p>
<h3 id="4247"><a href="lwg-defects.html#4247">4247</a>. Header <code>&lt;stdbit.h&gt;</code> is not yet freestanding</h3>
<p><b>Section:</b> 22.12 <a href="https://wg21.link/stdbit.h.syn">[stdbit.h.syn]</a> <b>Status:</b> <a href="lwg-active.html#WP">WP</a>
 <b>Submitter:</b> Jiang An <b>Opened:</b> 2025-04-24 <b>Last modified:</b> 2025-06-23</p>
<p><b>Priority: </b>Not Prioritized
</p>
<p><b>View all issues with</b> <a href="lwg-status.html#WP">WP</a> status.</p>
<p><b>Discussion:</b></p>
<p>
Per C23/WG14 <a href="https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3220.pdf#page=22">N3220</a> 4 p7, <code>&lt;stdbit.h&gt;</code> 
is freestanding in C23, but C++ hasn't required it for a freestanding implementation. 
LWG <a href="lwg-active.html#4049" title="C &lt;foo.h&gt; headers not in freestanding (Status: New)">4049</a><sup><a href="https://cplusplus.github.io/LWG/issue4049" title="Latest snapshot">(i)</a></sup> is related but doesn't cover this, because there's no <code>&lt;cstdbit&gt;</code> standard header.
</p>

<p><i>[2025-06-12; Reflector poll]</i></p>

<p>
Set status to Tentatively Ready after six votes in favour during reflector poll.
</p>

<p><i>[Sofia 2025-06-21; Status changed: Voting &rarr; WP.]</i></p>



<p id="res-4247"><b>Proposed resolution:</b></p>
<p>
This wording is relative to <a href="https://wg21.link/N5008" title=" Working Draft, Programming Languages — C++">N5008</a>.
</p>

<ol>

<li><p>Modify Table 27 [tab:headers.cpp.fs] as indicated:</p>

<blockquote>
<table border="1">
<caption>Table 27: C++ headers for freestanding implementations [tab:headers.cpp.fs]</caption>
<tr align="center">
<th></th>
<th>Subclause</th>
<th>Header</th>
</tr> 

<tr>
<td colspan="3" align="center">
<code>[&hellip;]</code>
</td>
</tr>

<tr>
<td>
22.11 <a href="https://wg21.link/bit">[bit]</a>
</td>
<td>
Bit manipulation
</td>
<td>
<code>&lt;bit&gt;</code>
</td>
</tr>

<tr>
<td>
<ins>22.12 <a href="https://wg21.link/stdbit.h.syn">[stdbit.h.syn]</a></ins>
</td>
<td>
<ins>C-compatible bit manipulation</ins>
</td>
<td>
<ins><code>&lt;stdbit.h&gt;</code></ins>
</td>
</tr>

<tr>
<td>
23.3.3 <a href="https://wg21.link/array">[array]</a>
</td>
<td>
Class template <code class='backtick'>array</code>
</td>
<td>
<code>&lt;array&gt;</code>
</td>
</tr>

<tr>
<td colspan="3" align="center">
<code>[&hellip;]</code>
</td>
</tr>

</table>

</blockquote>

</li>

<li><p>Modify 22.12 <a href="https://wg21.link/stdbit.h.syn">[stdbit.h.syn]</a>, header <code>&lt;stdbit.h&gt;</code> synopsis, as indicated:</p>

<blockquote>
<pre>
<ins><i>// all freestanding</i></ins>
#define __STDC_VERSION_STDBIT_H__ 202311L

#define __STDC_ENDIAN_BIG__    <i>see below</i>
#define __STDC_ENDIAN_LITTLE__ <i>see below</i>
#define __STDC_ENDIAN_NATIVE__ <i>see below</i>

[&hellip;]
</pre>
</blockquote>

</li>

</ol>





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