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    CWG Issue 1638</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="1638"></A><H4>1638.
  
Declaring an explicit specialization of a scoped enumeration
</H4>
<B>Section: </B>9.8.1&#160; [<A href="https://wg21.link/dcl.enum">dcl.enum</A>]
 &#160;&#160;&#160;

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

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

 <B>Date: </B>2013-03-12<BR>


<P>[Adopted at the February, 2016 meeting.]</P>



<P>There is no syntax currently for declaring an explicit specialization of
a member scoped enumeration.  A declaration (not a definition) of such an
explicit specialization most resembles an <I>opaque-enum-declaration</I>,
but the grammar for that requires that the name be a simple identifier,
which will not be the case for an explicit specialization of a member
enumeration.  This could be remedied by adding
a <I>nested-name-specifier</I> to the grammar with a restriction that
a <I>nested-name-specifier</I> only appear in an explicit
specialization.</P>

<P><B>Proposed resolution (October, 2015):</B></P>

<OL>
<LI><P>Change the grammar in 9.8.1 [<A href="https://wg21.link/dcl.enum">dcl.enum</A>] paragraph
1 as follows:</P></LI>

<UL>
<I>opaque-enum-declaration:</I>
<UL>
<I>enum-key attribute-specifier-seq<SUB>opt</SUB> <INS>nested-name-specifier<SUB>opt</SUB></INS> identifier enum-base<SUB>opt</SUB></I> <TT>;</TT>
</UL>
</UL>

<LI><P>Add the following at the end of 9.8.1 [<A href="https://wg21.link/dcl.enum#1">dcl.enum</A>] paragraph 1:
</P></LI>

<BLOCKQUOTE>

<INS>If an <I>opaque-enum-declaration</I> contains a
<I>nested-name-specifier</I>, the declaration shall be an
explicit specialization (13.9.4 [<A href="https://wg21.link/temp.expl.spec">temp.expl.spec</A>]).</INS>

</BLOCKQUOTE>

</OL>

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