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    CWG Issue 741</TITLE>
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<P><EM>This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21
  Core Issues List revision 118b.
  See http://www.open-std.org/jtc1/sc22/wg21/ for the official
  list.</EM></P>
<P>2025-09-28</P>
<HR>
<A NAME="741"></A><H4>741.
  
&#8220;plain&#8221; <TT>long long</TT> bit-fields
</H4>
<B>Section: </B>11.4.10&#160; [<A href="https://wg21.link/class.bit">class.bit</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++11
 &#160;&#160;&#160;

 <B>Submitter: </B>Mike Miller
 &#160;&#160;&#160;

 <B>Date: </B>7 November, 2008<BR>


<P>[Voted into WP at August, 2010 meeting.]</P>

<P>The type <TT>long long</TT> is missing from the list of bit-field
types in 11.4.10 [<A href="https://wg21.link/class.bit#3">class.bit</A>] paragraph 3 for which the
implementation can choose the signedness.  This was presumably an
oversight.  (If that is the case, we may want to reconsider the
handling of 7.3.7 [<A href="https://wg21.link/conv.prom#3">conv.prom</A>] paragraph 3: a <TT>long long</TT>
bit-field that the implementation treats as unsigned will &#8212;
pending the outcome of <A HREF="739.html">issue 739</A> &#8212;
still promote to <TT>signed long long</TT>, which can lead to
unexpected results for bit-fields with the same number of bits as
<TT>long long</TT>.)</P>

<P><B>Proposed resolution (February, 2010):</B></P>

<P>Change 11.4.10 [<A href="https://wg21.link/class.bit#3">class.bit</A>] paragraph 3 as follows:</P>

<BLOCKQUOTE>

...It is implementation-defined whether a plain (neither
explicitly signed nor unsigned) <TT>char</TT>, <TT>short</TT>,
<TT>int</TT><DEL> or</DEL><INS>,</INS> <TT>long</TT><INS>, or
<TT>long long</TT></INS> bit-field is signed or unsigned...

</BLOCKQUOTE>

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