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    CWG Issue 743</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="743"></A><H4>743.
  
Use of <TT>decltype</TT> in a <I>nested-name-specifier</I>
</H4>
<B>Section: </B>_N4567_.5.1.1&#160; [<A href="https://wg21.link/expr.prim.general">expr.prim.general</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD2
 &#160;&#160;&#160;

 <B>Submitter: </B>Jaakko J&#228;rvi
 &#160;&#160;&#160;

 <B>Date: </B>12 November, 2008<BR><BR>


<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3086.html#JP8">N2800 comment
  JP&#160;8<BR></A>

<P>[Voted into WP at March, 2010 meeting as document N3049.]</P>



<P>The grammar for <I>nested-name-specifier</I> in _N4567_.5.1.1 [<A href="https://wg21.link/expr.prim.general#7">expr.prim.general</A>] paragraph 7
does not allow <TT>decltype</TT> to be used in a
<I>qualified-id</I>.  This could be useful for cases like:</P>

<PRE>
   auto vec = get_vec();
   decltype(vec)::value_type v = vec.first();
</PRE>

(See also <A HREF="950.html">issue 950</A>.)

<P><B>Proposed resolution (September, 2009):</B></P>

<P>See paper PL22.16/09-0181 = WG21 N2991.</P>

<P><B>Proposed resolution (February, 2010):</B></P>

<P>See paper PL22.16/10-0021 = WG21 N3031.</P>

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