<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 2031</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="2031"></A><H4>2031.
  
Missing incompatibility for <TT>&amp;&amp;</TT>
</H4>
<B>Section: </B>C.6.3&#160; [<A href="https://wg21.link/diff.cpp03.expr">diff.cpp03.expr</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Melissa Mears
 &#160;&#160;&#160;

 <B>Date: </B>2014-10-31<BR>


<P>[Moved to DR at the October, 2015 meeting.]</P>

<P>The introduction of rvalue references in C++11 changed the
interpretation of some previously well-formed examples such as
the following:</P>

<PRE>
  struct Struct { template &lt;typename T&gt; operator T(); };
  bool example_1 = new int &amp;&amp; false;               //<SPAN CLASS="cmnt"> #1</SPAN>
  bool example_2 = &amp;Struct::operator int &amp;&amp; false; //<SPAN CLASS="cmnt"> #2</SPAN>
</PRE>

<P>Previously the <TT>&amp;&amp;</TT> was interpreted as an operator,
while it is now part of a <I>type-name</I>.  However, this change is
not mentioned in Annex Clause Annex C [<A href="https://wg21.link/diff">diff</A>].</P>

<P><B>Proposed resolution (May, 2015):</B></P>

<P>Add the following as a new subsection in C.6.3 [<A href="https://wg21.link/diff.cpp03.expr">diff.cpp03.expr</A>]:</P>

<BLOCKQUOTE>

<P>7.6.15 [<A href="https://wg21.link/expr.log.or">expr.log.or</A>]<BR>
<B>Change:</B> <TT>&amp;&amp;</TT> is valid in a <I>type-name</I><BR>
<B>Rationale:</B> Required for new features<BR>
<B>Effect on original feature:</B> Valid C++ 2003 code may fail to
compile or produce different results in this International
Standard, as the following example illustrates:</P>

<PRE>
  bool b1 = new int &amp;&amp; false;           //<SPAN CLASS="cmnt"> previously </SPAN>false<SPAN CLASS="cmnt">, now ill-formed</SPAN>
  struct S { operator int(); };
  bool b2 = &amp;S::operator int &amp;&amp; false;  //<SPAN CLASS="cmnt"> previously </SPAN>false<SPAN CLASS="cmnt">, now ill-formed</SPAN>
</PRE>

</BLOCKQUOTE>

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