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    CWG Issue 816</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="816"></A><H4>816.
  
Diagnosing violations of <TT>[[final]]</TT>
</H4>
<B>Section: </B>_N3225_.7.6.4&#160; [<A href="https://wg21.link/dcl.attr.final">dcl.attr.final</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>UK
 &#160;&#160;&#160;

 <B>Date: </B>3 March, 2009<BR><BR>


<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2010/n3086.html#UK108">N2800 comment
  UK&#160;108<BR></A>

<P>[Voted into WP at July, 2009 meeting.]</P>

<P>According to _N3225_.7.6.4 [<A href="https://wg21.link/dcl.attr.final#2">dcl.attr.final</A>] paragraph 2, overriding a
virtual function with the <TT>[[final]]</TT> attribute renders a program
ill-formed, but no diagnostic is required.  This is easily diagnosable
and a diagnostic should be required in this case.</P>

<P><B>Notes from the March, 2009 meeting:</B></P>

<P>This specification was a deliberate decision on the part of the
EWG; the general rule was that it should be possible to ignore
attributes without changing the meaning of a program.  However, the
consensus of the CWG was that violation of the <TT>[[final]]</TT>
attribute should require a diagnostic.</P>

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

<P>Change _N3225_.7.6.4 [<A href="https://wg21.link/dcl.attr.final#2">dcl.attr.final</A>] paragraph 2 as follows:</P>

<BLOCKQUOTE>

If a virtual member function <TT>f</TT> in some class <TT>B</TT> is
marked <TT>final</TT> and in a class <TT>D</TT> derived from
<TT>B</TT> a function <TT>D::f</TT> overrides <TT>B::f</TT>, the
program is ill-formed<DEL>; no diagnostic
required</DEL>. <DEL>[<I>Footnote:</I> If an implementation does not emit
a diagnostic it should execute the program as if final were not
present. &#8212;<I>end footnote</I>]</DEL>

</BLOCKQUOTE>

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