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    CWG Issue 945</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="945"></A><H4>945.
  
Use of <TT>this</TT> in a late-specified return type
</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>C++11
 &#160;&#160;&#160;

 <B>Submitter: </B>Alisdair Meredith
 &#160;&#160;&#160;

 <B>Date: </B>18 July, 2009<BR>


<P>(Moved from <A HREF="760.html">issue 760</A>.)</P>

<P>Although it was considered and rejected as part of
<A HREF="643.html">issue 643</A>, more recent developments
may argue in favor of allowing the use of <TT>this</TT> in a
late-specified return type.  In particular, declaring the return
type for a forwarding function in a derived class template that invokes
a member function of a dependent base class is difficult without
this facility.  For example:</P>

<PRE>
    template &lt;typename T&gt; struct derived: base&lt;T&gt; {
      auto invoke() -&gt; decltype(this-&gt;base_func()) {
        return this-&gt;base_func();
      }
    };
</PRE>

<P>(See also <A HREF="1207.html">issue 1207</A> for another
potential motivation for a change to this rule.)</P>

<P><B>Additional note (October, 2010):</B></P>



<P>The question should also be considered for parameter types; for
example,</P>

<PRE>
class comparable {
public:
   bool is_equal(decltype(*this) other) { // should be X&amp;
       return /*...*/;
   }
};
</PRE>

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

<P>This issue is resolved by the resolution of issues
<A HREF="1017.html">1017</A> and <A HREF="1207.html">1207</A>
in document N3282.</P>

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