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    CWG Issue 1780</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="1780"></A><H4>1780.
  
Explicit instantiation/specialization of generic lambda <TT>operator()</TT>
</H4>
<B>Section: </B>7.5.6.2&#160; [<A href="https://wg21.link/expr.prim.lambda.closure">expr.prim.lambda.closure</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Hubert Tong
 &#160;&#160;&#160;

 <B>Date: </B>2013-09-26<BR>


<P>[Moved to DR at the November, 2014 meeting.]</P>

<P>Similarly to <A HREF="1738.html">issue 1738</A>, it is not clear
whether it is permitted to explicitly instantiate or specialize the
call operator of a polymorphic lambda (via <TT>decltype</TT>).</P>

<P><B>Proposed resolution (February, 2014):</B></P>

<P>Add the following as a new paragraph following 7.5.6 [<A href="https://wg21.link/expr.prim.lambda#21">expr.prim.lambda</A>] paragraph 21:
</P>

<BLOCKQUOTE>

<P>The closure type associated with a <I>lambda-expression</I> has an
implicitly-declared destructor (11.4.7 [<A href="https://wg21.link/class.dtor">class.dtor</A>]).</P>

<P><INS>A member of a closure type shall not be explicitly instantiated
(13.9.2 [<A href="https://wg21.link/temp.inst">temp.inst</A>]), explicitly specialized
(13.9.3 [<A href="https://wg21.link/temp.explicit">temp.explicit</A>]), or named in a <TT>friend</TT>
declaration (11.8.4 [<A href="https://wg21.link/class.friend">class.friend</A>]).</INS></P>

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