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    CWG Issue 477</TITLE>
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<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="477"></A><H4>477.
  
Can <TT>virtual</TT> appear in a <TT>friend</TT> declaration?
</H4>
<B>Section: </B>9.2.3&#160; [<A href="https://wg21.link/dcl.fct.spec">dcl.fct.spec</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD1
 &#160;&#160;&#160;

 <B>Submitter: </B>Daveed Vandevoorde
 &#160;&#160;&#160;

 <B>Date: </B>23 Sep 2004<BR>


<P>[Voted into WP at the October, 2006 meeting.]</P>

<P>I couldn't find wording that makes it invalid to say
<TT>friend&#160;virtual...</TT>  The closest seems to be
9.2.3 [<A href="https://wg21.link/dcl.fct.spec#5">dcl.fct.spec</A>] paragraph 5, which says:</P>

<BLOCKQUOTE>

The <TT>virtual</TT> specifier shall only be used in declarations
of nonstatic class member functions that appear within a
<I>member-specification</I> of a class definition; see
11.7.3 [<A href="https://wg21.link/class.virtual">class.virtual</A>].

</BLOCKQUOTE>

<P>I don't think that excludes a friend declaration (which is a
valid <I>member-specification</I> by 11.4 [<A href="https://wg21.link/class.mem">class.mem</A>]).</P>

<P>
<U>John Spicer</U>: I agree that virtual should not be allowed
on friend declarations.  I think the wording in 9.2.3 [<A href="https://wg21.link/dcl.fct.spec">dcl.fct.spec</A>] is intended to be <I>the</I> declaration of a
function within its class, although I think the wording should be
improved to make it clearer.</P>

<P><B>Proposed resolution (October, 2005):</B></P>

<P>Change 9.2.3 [<A href="https://wg21.link/dcl.fct.spec">dcl.fct.spec</A>] paragraphs 5-6 as indicated:</P>

<BLOCKQUOTE>

<P>The <TT>virtual</TT> specifier shall <DEL>only</DEL> be
used <INS>only</INS> in <DEL>declarations</DEL> <INS>the initial declaration</INS>
of <INS>a</INS> non-static class member <DEL>functions that appear within a
<I>member-specification</I> of a class definition</DEL> <INS>function</INS>;
see 11.7.3 [<A href="https://wg21.link/class.virtual">class.virtual</A>].</P>

<P>The <TT>explicit</TT> specifier shall be used only
in <DEL>declarations</DEL> <INS>the declaration</INS> of <DEL>constructors</DEL>
<INS>a constructor</INS> within <DEL>a</DEL> <INS>its</INS> class definition; see
11.4.8.2 [<A href="https://wg21.link/class.conv.ctor">class.conv.ctor</A>].</P>

</BLOCKQUOTE>

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