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    CWG Issue 2156</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="2156"></A><H4>2156.
  
Definition of enumeration declared by <I>using-declaration</I>
</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>2015-07-06<BR>


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



<P>The description of enumeration declarations in 9.8.1 [<A href="https://wg21.link/dcl.enum">dcl.enum</A>]
does not, but should, contain similar wording to that preventing
a class definition from defining a class type named by a
<I>using-declaration</I>:</P>

<BLOCKQUOTE>

If a <I>class-head-name</I> contains
a <I>nested-name-specifier</I>, the <I>class-specifier</I>
shall refer to a class that was previously declared directly
in the class or namespace to which
the <I>nested-name-specifier</I> refers, or in an element of
the inline namespace set (9.9.2 [<A href="https://wg21.link/namespace.def">namespace.def</A>]) of
that namespace (i.e., not merely inherited or introduced by
a <I>using-declaration</I>), and the <I>class-specifier</I>
shall appear in a namespace enclosing the previous
declaration.  In such cases,
the <I>nested-name-specifier</I> of
the <I>class-head-name</I> of the definition shall not begin
with a <I>decltype-specifier</I>.

</BLOCKQUOTE>

<P><B>Proposed resolution (February, 2016):</B></P>

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

<BLOCKQUOTE>

<INS>If an <I>enum-head</I> contains a <I>nested-name-specifier</I>,
the <I>enum-specifier</I> shall refer to an enumeration that was
previously declared directly in the class or namespace to which the
<I>nested-name-specifier</I> refers, or in an element of the
inline namespace set (9.9.2 [<A href="https://wg21.link/namespace.def">namespace.def</A>]) of that
namespace (i.e., not merely inherited or introduced by
a <I>using-declaration</I>), and the <I>enum-specifier</I>
shall appear in a namespace enclosing the previous
declaration.  In such cases,
the <I>nested-name-specifier</I> of the <I>enum-head</I> of the
definition shall not begin with a <I>decltype-specifier</I>.</INS>

</BLOCKQUOTE>

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