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    CWG Issue 1193</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="1193"></A><H4>1193.
  
Use of address-constant pointers in constant expressions
</H4>
<B>Section: </B>7.7&#160; [<A href="https://wg21.link/expr.const">expr.const</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Daniel Kr&#252;gler
 &#160;&#160;&#160;

 <B>Date: </B>2010-09-02<BR>


<P>[Voted into the WP at the March, 2011 meeting.]</P>



<P>It's not clear whether the current rules for constant expressions
allow indirect calls of constexpr functions and constexpr member
functions; for example,</P>

<PRE>
    constexpr bool is_negative(int x) { return x &lt; 0; }
    constexpr bool check(int x, bool (*p)(int)) { return p(x); }
    static_assert(check(-2, is_negative), "Error");
</PRE>

<P>If this is to be permitted, there does not seem to be a reason to
prohibit equality comparison of pointers to functions or pointers to
objects of static storage duration -- these can be tracked as is
already done for non-type template parameters.</P>

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

<P>Change 7.7 [<A href="https://wg21.link/expr.const#2.19">expr.const</A>] bullet 2.19 as follows:</P>

<UL><LI><P>a relational (7.6.9 [<A href="https://wg21.link/expr.rel">expr.rel</A>]) or equality
(7.6.10 [<A href="https://wg21.link/expr.eq">expr.eq</A>]) operator where <DEL>at least one of the
operands is a pointer</DEL> <INS>the result is
unspecified</INS>;</P></LI></UL>

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