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    CWG Issue 2647</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="2647"></A><H4>2647.
  
Fix for "needed for constant evaluation"
</H4>
<B>Section: </B>7.7&#160; [<A href="https://wg21.link/expr.const">expr.const</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++23
 &#160;&#160;&#160;

 <B>Submitter: </B>US
 &#160;&#160;&#160;

 <B>Date: </B>2022-11-03<BR><BR>


<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2720r0.pdf#US17-047">P2720R0 comment
  US&#160;17-047<BR></A>

<P>[Accepted as a DR at the November, 2022 meeting.]</P>

<P>The criteria for a variable to be needed for constant evaluation
are inconsistent with those for it to be usable in constant
expressions (/4).</P>

<P><B>Proposed resolution (approved by CWG 2022-11-08):</B></P>

<OL>

<LI>
<P>Change in 7.7 [<A href="https://wg21.link/expr.const#3">expr.const</A>] paragraph 3 as follows:</P>

<BLOCKQUOTE>

A variable is <I>potentially-constant</I> if it is constexpr or it has
reference or <INS>non-volatile</INS> const-qualified integral or
enumeration type.

</BLOCKQUOTE>

</LI>

<LI>
<P>Change in 7.7 [<A href="https://wg21.link/expr.const#16.7">expr.const</A>] paragraph 16.7 as follows:</P>

<BLOCKQUOTE>

A function or variable is needed for constant evaluation if it is:
<UL>
<LI>
a constexpr function that is named by an expression (6.3) that is
potentially constant evaluated, or
</LI>

<LI>
a <INS>potentially-constant</INS> variable named by a potentially
constant evaluated expression <DEL>that is either a constexpr variable
or is of non-volatile const-qualified integral type or of reference
type</DEL>.

</LI>
</UL>

</BLOCKQUOTE>

</LI>

</OL>

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