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    CWG Issue 518</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="518"></A><H4>518.
  
Trailing comma following <I>enumerator-list</I>
</H4>
<B>Section: </B>9.8.1&#160; [<A href="https://wg21.link/dcl.enum">dcl.enum</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Charles Bryant
 &#160;&#160;&#160;

 <B>Date: </B>10 May 2005<BR>


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

<P>The C language (since C99), and some C++ compilers, accept:</P>

<PRE>
    enum { FOO, };
</PRE>

<P>as syntactically valid. It would be useful</P>

<UL>

<LI><P>for machine generated code</P></LI>

<LI><P>for minimising changes when editing</P></LI>

<LI><P>to allow a distinction between the final item being intended as
an ordinary item or as a limit:</P></LI>

<PRE>
  enum { red, green, blue, num_colours };  // note no comma
  enum { fred, jim, sheila, };             // last is not special
</PRE>

</UL>

<P>This proposed change is to permit a trailing comma in enum by adding:</P>

<BLOCKQUOTE>

<TT>enum</TT> <I>identifier<SUB>opt</SUB></I> <TT>{</TT> <I>enumerator-list</I> <TT>,</TT> <TT>}</TT>

</BLOCKQUOTE>

<P>as an alternative definition for the <I>enum-specifier</I> nonterminal
in 9.8.1 [<A href="https://wg21.link/dcl.enum#1">dcl.enum</A>] paragraph 1.</P>

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

<P>Change the grammar in 9.8.1 [<A href="https://wg21.link/dcl.enum#1">dcl.enum</A>] paragraph 1 as
indicated:</P>

<BLOCKQUOTE>

<I>enum-specifier:</I>
<UL>
<TT>enum</TT> <I>identifier<SUB>opt</SUB> </I><TT>{</TT><I> enumerator-list<SUB>opt</SUB> </I><TT>}</TT>
</UL>
<INS><UL>
<TT>enum</TT> <I>identifier<SUB>opt</SUB> </I><TT>{</TT><I> enumerator-list </I><TT>,</TT> <TT>}</TT>
</UL></INS>

</BLOCKQUOTE>

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