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    CWG Issue 1858</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="1858"></A><H4>1858.
  
Comparing pointers to union members
</H4>
<B>Section: </B>7.6.10&#160; [<A href="https://wg21.link/expr.eq">expr.eq</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD4
 &#160;&#160;&#160;

 <B>Submitter: </B>Richard Smith
 &#160;&#160;&#160;

 <B>Date: </B>2014-02-12<BR>


<P>[Moved to DR at the November, 2014 meeting.]</P>

<P>Comparison of pointers to members is currently specified in
7.6.10 [<A href="https://wg21.link/expr.eq#3">expr.eq</A>] paragraph 3 as,</P>

<BLOCKQUOTE>

two pointers to members compare equal if they would refer to the same
member of the same most derived object (6.8.2 [<A href="https://wg21.link/intro.object">intro.object</A>]) or the
same subobject if indirection with a hypothetical object of the associated
class type were performed, otherwise they compare unequal.

</BLOCKQUOTE>

<P>The &#8220;same member&#8221; requirement could be interpreted as
incorrect for union members.  The wording should be clarified in this
regard.</P>

<P><B>Proposed Resolution (July, 2014):</B></P>

<P>Insert the following before bullet 5 of 7.6.10 [<A href="https://wg21.link/expr.eq#3">expr.eq</A>] paragraph 3:
</P>

<UL>
<LI><P>...</P></LI>

<LI><P><INS>If both refer to (possibly different) members of the same
union (11.5 [<A href="https://wg21.link/class.union">class.union</A>]), they compare equal.</INS></P></LI>

<LI><P>Otherwise, two pointers to members compare equal if...</P></LI>

</UL>

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