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    CWG Issue 1815</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="1815"></A><H4>1815.
  
Lifetime extension in aggregate initialization
</H4>
<B>Section: </B>9.5.2&#160; [<A href="https://wg21.link/dcl.init.aggr">dcl.init.aggr</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Dinka Ranns
 &#160;&#160;&#160;

 <B>Date: </B>2013-11-22<BR>


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



<P>With the recent addition of <I>brace-or-equal-initializer</I>s to
aggregates and the presumed resolution for
<A HREF="1696.html">issue 1696</A>, it is not clear how
lifetime extension of temporaries should work in aggregate
initialization.  For example:</P>

<PRE>
  struct A { };
  struct B { A&amp;&amp; a { A{} } };
  B b;         //<SPAN CLASS="cmnt"> #1</SPAN>
  B b{ A{} };  //<SPAN CLASS="cmnt"> #2</SPAN>
  B b{};       //<SPAN CLASS="cmnt"> #3</SPAN>
</PRE>

<P>#1 is default initialization, so (presumably) the lifetime of the
temporary persists only until <TT>B</TT>'s default constructor
exits.  #2 is aggregate initialization, which binds <TT>B::a</TT> to
the temporary in the initializer for <TT>b</TT> and thus extends its
lifetime to that of <TT>b</TT>.  #3 is aggregate initialization, but
it is not clear whether the lifetime of the temporary in the
non-static data member initializer for <TT>B::a</TT> should be
lifetime-extended like #2 or not, like #1.</P>

<P>One possibility might be to extend the lifetime in #3 but to give
<TT>B</TT> a deleted default constructor since it would extend the
lifetime of a temporary.</P>

<P>See also <A HREF="1696.html">issue 1696</A>.</P>

<P><B>Notes from the February, 2014 meeting:</B></P>

<P>CWG agreed with the suggested direction, which would treat #3 in the
example like #2 and make the default constructor deleted, resulting
in #1 being ill-formed.</P>

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

<P>This issue is resolved by the resolution of
<A HREF="1696.html">issue 1696</A>.</P>

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