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    CWG Issue 355</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="355"></A><H4>355.
  
Global-scope <TT>::</TT> in <I>nested-name-specifier</I>
</H4>
<B>Section: </B>Clause 11&#160; [<A href="https://wg21.link/class">class</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Clark Nelson
 &#160;&#160;&#160;

 <B>Date: </B>16 May 2002<BR>


<P>[Voted into the WP at the March, 2011 meeting as paper N3259.]</P>



<P>
In looking at a large handful of core issues related to
<I>elaborated-type-specifier</I>s and the naming of classes in general, I
discovered an odd fact. It turns out that there is exactly one place in the
grammar where <I>nested-name-specifier</I>
is not immediately preceded by "<TT>::</TT><SUB><I>opt</I></SUB>":
in <I>class-head</I>, which is used only for class definitions. So technically,
this example is ill-formed, and should evoke a syntax error:
</P>
<PRE>
  struct A;
  struct ::A { };
</PRE>
<P>
However, all of EDG, GCC and Microsoft's compiler accept it without a qualm.
In fact, I couldn't get any of them to even warn about it.</P>

<P><B>Suggested resolution:</B></P>

<P>It would simplify the grammar, and apparently better reflect existing
practice, to factor the global-scope operator into the rule for
<I>nested-name-specifier</I>.</P>

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

<P>The proposed resolution will be submitted as a separate document.</P>

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