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    CWG Issue 1060</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="1060"></A><H4>1060.
  
Scoped enumerators in integral 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>Jonathan Caves
 &#160;&#160;&#160;

 <B>Date: </B>2010-03-21<BR>


<P>[Voted into the WP at the March, 2011 meeting as part of paper N3260.]</P>



<P>According to 7.7 [<A href="https://wg21.link/expr.const#3">expr.const</A>] paragraph 3,</P>

<BLOCKQUOTE>

A constant expression is an <I>integral constant expression</I>
if it is of integral or enumeration type. [<I>Note:</I> such
expressions may be used as array bounds (9.3.4.5 [<A href="https://wg21.link/dcl.array">dcl.array</A>], 7.6.2.8 [<A href="https://wg21.link/expr.new">expr.new</A>]), as case expressions
(8.5.3 [<A href="https://wg21.link/stmt.switch">stmt.switch</A>]), as bit-field lengths (11.4.10 [<A href="https://wg21.link/class.bit">class.bit</A>]), as enumerator initializers (9.8.1 [<A href="https://wg21.link/dcl.enum">dcl.enum</A>]), and as integral or enumeration non-type template
arguments (13.4 [<A href="https://wg21.link/temp.arg">temp.arg</A>]). &#8212;<I>end note</I>]

</BLOCKQUOTE>

<P>Although there is conceptually a conversion from enumeration
type to integral type involved in using an enumerator as an array
bound or bit-field length, the normative wording for those uses
does not explicitly mention it and simply requires an integral
constant expression.  Consequently, the current wording permits
uses like the following:</P>

<PRE>
    enum class E { e = 10; };
    struct S {
        int arr[E::e];
        int i: E::e;
    };
</PRE>

<P>This seems surprising.</P>

<P><B>Proposed resolution (February, 2011):</B></P>

<P>This issue is resolved by the resolution of
<A HREF="1197.html">issue 1197</A>.</P>

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