<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 1224</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="1224"></A><H4>1224.
  
<TT>constexpr</TT> defaulted copy constructors
</H4>
<B>Section: </B>11.4.5.3&#160; [<A href="https://wg21.link/class.copy.ctor">class.copy.ctor</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++11
 &#160;&#160;&#160;

 <B>Submitter: </B>Jason Merrill
 &#160;&#160;&#160;

 <B>Date: </B>2010-10-25<BR>


<P>[Voted into the WP at the March, 2011 meeting as part of paper N3262.]</P>



<P>11.4.5 [<A href="https://wg21.link/class.ctor">class.ctor</A>] allows for a defaulted default
constructor to be <TT>constexpr</TT>, but 11.4.5.3 [<A href="https://wg21.link/class.copy.ctor">class.copy.ctor</A>]
does not do the same for a defaulted copy constructor.  This seems
wrong.</P>

<P><B>Proposed resolution (November, 2010) [SUPERSEDED]:</B></P>

<P>Change 11.4.5.3 [<A href="https://wg21.link/class.copy.ctor#14">class.copy.ctor</A>] paragraph 14 as follows:</P>

<BLOCKQUOTE>

A copy/move constructor that is defaulted and not defined as deleted
is <I>implicitly defined</I> if it is odr-used (6.3 [<A href="https://wg21.link/basic.def.odr">basic.def.odr</A>]) to initialize an object of its class type from a copy of
an object of its class type or of a class type derived from its class
type<SUP>123</SUP> or when it is explicitly defaulted after its first
declaration.  [<I>Note:</I> the copy/move constructor is implicitly
defined even if the implementation elided its odr-use (6.3 [<A href="https://wg21.link/basic.def.odr">basic.def.odr</A>], 6.8.7 [<A href="https://wg21.link/class.temporary">class.temporary</A>]). &#8212;<I>end note</I>]
<INS>If the implicitly-defined constructor would satisfy the
requirements of a <TT>constexpr</TT> constructor (9.2.6 [<A href="https://wg21.link/dcl.constexpr">dcl.constexpr</A>]), the implicitly-defined constructor is
<TT>constexpr</TT>.</INS>

</BLOCKQUOTE>

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