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    CWG Issue 1018</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="1018"></A><H4>1018.
  
Ambiguity between <I>simple-declaration</I> and <I>attribute-declaration</I>
</H4>
<B>Section: </B>9.1&#160; [<A href="https://wg21.link/dcl.pre">dcl.pre</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++11
 &#160;&#160;&#160;

 <B>Submitter: </B>Mike Miller
 &#160;&#160;&#160;

 <B>Date: </B>2010-01-04<BR>


<P>[Voted into the WP at the March, 2011 meeting as part of paper N3262.]</P>

<P>The grammar for declarations includes the following two nonterminals:</P>

<UL>
<I>simple-declaration:</I>
<UL>
<I>attribute-specifier<SUB>opt</SUB> decl-specifier-seq<SUB>opt</SUB> init-declarator-list<SUB>opt</SUB></I> <TT>;</TT>
</UL>
</UL>

<UL>
<I>attribute-declaration:</I>
<UL>
<I>attribute-specifier</I> <TT>;</TT>
</UL>
</UL>

<P>An <I>attribute-specifier</I> followed by a semicolon could thus
be parsed as either an <I>attribute-declaration</I> or as a
<I>simple-declaration</I> that omits the optional
<I>decl-specifier-seq</I> and <I>init-declarator-list</I>, and the
current wording does not disambiguate the two.  (There doesn't seem
to be a compelling need for <I>attribute-declaration</I> as a
separate nonterminal, given that <I>simple-declaration</I> can
accommodate that form.)</P>

<P><B>Proposed resolution (February, 2011) [SUPERSEDED]:</B></P>

<P>Change 9.1 [<A href="https://wg21.link/dcl.pre#1">dcl.pre</A>] paragraph 1 as follows:</P>

<UL>
<I>simple-declaration:</I>
<UL>
<I><DEL>attribute-specifier-seq<SUB>opt</SUB></DEL> decl-specifier-seq<SUB>opt</SUB> init-declarator-list<SUB>opt</SUB></I> <TT>;</TT><BR>
<INS><I>attribute-specifier-seq decl-specifier-seq init-declarator-list</I> <TT>;</TT></INS>
</UL>

</UL>

<BLOCKQUOTE>

...The <DEL>optional</DEL> <I>attribute-specifier-seq</I> in a
<I>simple-declaration</I> appertains to each of the entities declared
by the <I>declarator</I>s<DEL>; it shall not appear if the optional</DEL>
<INS>of the</INS> <I>init-declarator-list</I> <DEL>is omitted</DEL>...

</BLOCKQUOTE>

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