<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 858</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="858"></A><H4>858.
  
Example binding an rvalue reference to an lvalue
</H4>
<B>Section: </B>Clause 7&#160; [<A href="https://wg21.link/expr">expr</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD2
 &#160;&#160;&#160;

 <B>Submitter: </B>Daniel Kr&#252;gler
 &#160;&#160;&#160;

 <B>Date: </B>6 April, 2009<BR>


<P>[Voted into WP at March, 2010 meeting as part of document N3055.]</P>



<P>The adoption of paper N2844 made it ill-formed to attempt to bind
an rvalue reference to an lvalue, but the example in Clause 7 [<A href="https://wg21.link/expr#6">expr</A>] paragraph 6
was overlooked in making this change:</P>

<PRE>
    struct A { };
    A&amp;&amp; operator+(A, A);
    A&amp;&amp; f();

    A a;
    A&amp;&amp; ar = a;
</PRE>

<P>The last line should be changed to use something like
<TT>static_cast&lt;A&amp;&amp;&gt;(a)</TT>.</P>

<P>(See also <A HREF="847.html">issue 847</A>.)</P>

<P><B>Proposed resolution (July, 2009):</B></P>

<P>Change the example in Clause 7 [<A href="https://wg21.link/expr#6">expr</A>] paragraph 6 as follows:</P>

<BLOCKQUOTE>

<P>[<I>Example:</I>
</P>

<PRE>
  struct A { };
  A&amp;&amp; operator+(A, A);
  A&amp;&amp; f();

  A a;
  A&amp;&amp; ar = <INS>static_cast&lt;A&amp;&amp;&gt;(</INS>a<INS>)</INS>;
</PRE>

<P>The expressions <TT>f()</TT> and <TT>a + a</TT> are rvalues of type
<TT>A</TT>. The expression <TT>ar</TT> is an lvalue of type
<TT>A</TT>. &#8212;<I>end example</I>]</P>

</BLOCKQUOTE>

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