<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 1250</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="1250"></A><H4>1250.
  
Cv-qualification of incomplete virtual function return types
</H4>
<B>Section: </B>11.7.3&#160; [<A href="https://wg21.link/class.virtual">class.virtual</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD3
 &#160;&#160;&#160;

 <B>Submitter: </B>Jonathan Wakely
 &#160;&#160;&#160;

 <B>Date: </B>2011-03-03<BR>


<P>[Voted into the WP at the February, 2012 meeting;
moved to DR at the October, 2012 meeting.]</P>

<P>According to 11.7.3 [<A href="https://wg21.link/class.virtual#8">class.virtual</A>] paragraph 8,</P>

<BLOCKQUOTE>

If the return type of <TT>D::f</TT> differs from the return type of
<TT>B::f</TT>, the class type in the return type of <TT>D::f</TT>
shall be complete at the point of declaration of <TT>D::f</TT> or
shall be the class type <TT>D</TT>.

</BLOCKQUOTE>

<P>This provision was intended to deal with covariant return
types but inadvertently affects types that vary only in
cv-qualification:</P>

<PRE>
    struct A;
    struct B {
        virtual const A* f();
    };
    struct D : B {
        A* f();    // ill-formed
    };
</PRE>

<P><B>Proposed resolution (August, 2011):</B></P>

<P>Change 11.7.3 [<A href="https://wg21.link/class.virtual#8">class.virtual</A>] paragraph 8 as follows:</P>

<BLOCKQUOTE>

If the <INS>class type in the covariant</INS> return type of
<TT>D::f</TT> differs from <DEL>the return type</DEL> <INS>that</INS>
of <TT>B::f</TT>, the class type in the return type of <TT>D::f</TT>
shall be complete at the point of declaration of <TT>D::f</TT> or
shall be the class type <TT>D</TT>. When the overriding function...

</BLOCKQUOTE>

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