<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 2605</TITLE>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<STYLE TYPE="text/css">
  INS { text-decoration:none; font-weight:bold; background-color:#A0FFA0 }
  .INS { text-decoration:none; background-color:#D0FFD0 }
  DEL { text-decoration:line-through; background-color:#FFA0A0 }
  .DEL { text-decoration:line-through; background-color: #FFD0D0 }
  @media (prefers-color-scheme: dark) {
    HTML { background-color:#202020; color:#f0f0f0; }
    A { color:#5bc0ff; }
    A:visited { color:#c6a8ff; }
    A:hover, a:focus { color:#afd7ff; }
    INS { background-color:#033a16; color:#aff5b4; }
    .INS { background-color: #033a16; }
    DEL { background-color:#67060c; color:#ffdcd7; }
    .DEL { background-color:#67060c; }
  }
  SPAN.cmnt { font-family:Times; font-style:italic }
</STYLE>
</HEAD>
<BODY>
<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="2605"></A><H4>2605.
  
Implicit-lifetime aggregates
</H4>
<B>Section: </B>11.2&#160; [<A href="https://wg21.link/class.prop">class.prop</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++23
 &#160;&#160;&#160;

 <B>Submitter: </B>Davis Herring
 &#160;&#160;&#160;

 <B>Date: </B>2022-06-27<BR>


<P>[Accepted as a DR at the November, 2022 meeting.]</P>

<P>Subclause 11.2 [<A href="https://wg21.link/class.prop#9">class.prop</A>] paragraph 9 specifies:</P>

<BLOCKQUOTE>

A class S is an <I>implicit-lifetime class</I> if
<UL>
<LI>it is an aggregate or</LI>
<LI>it has at least one trivial eligible constructor and a trivial,
non-deleted destructor.</LI>
</UL>

</BLOCKQUOTE>

<P>However, an aggregate may have a non-deleted non-trivial destructor:</P>

<PRE>
  struct X {
    Y i;
    ~X();
  };
</PRE>

<P>This class is an aggregate, but destroying X itself (ignoring the
subobjects) does not satisfy "destroying an instance of the type runs
no code"; see P0593R6 "Implicit creation of objects for low-level
object manipulation" section 3.1.</P>

<P><B>Additional notes (September, 2022):</B></P>

<P>From a thread starting
<A HREF="http://lists.isocpp.org/core/2022/09/13217.php">here</A>:
What if <TT>X</TT> had a deleted destructor (either explicitly or
implicitly)?</P>

<P><B>CWG 2022-11-09:</B></P>

<P>A deleted destructor does not prevent an aggregate from being an
implicit-lifetime class.</P>

<P><B>Proposed resolution (approved by CWG 2022-11-09):</B></P>

<P>Change in 11.2 [<A href="https://wg21.link/class.prop#9">class.prop</A>] paragraph 9 as follows:</P>

<BLOCKQUOTE>

A class S is an <I>implicit-lifetime class</I> if
<UL>
<LI>it is an aggregate <INS>whose destructor is not user-provided</INS> or</LI>
<LI>it has at least one trivial eligible constructor and a trivial,
non-deleted destructor.</LI>
</UL>

</BLOCKQUOTE>

<BR><BR>
</BODY>
</HTML>
