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    CWG Issue 2040</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="2040"></A><H4>2040.
  
<I>trailing-return-type</I> no longer ambiguous
</H4>
<B>Section: </B>9.3&#160; [<A href="https://wg21.link/dcl.decl">dcl.decl</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD4
 &#160;&#160;&#160;

 <B>Submitter: </B>Jens Maurer
 &#160;&#160;&#160;

 <B>Date: </B>2014-11-09<BR>


<P>[Adopted at the February, 2016 meeting.]</P>

<P>According to 9.3 [<A href="https://wg21.link/dcl.decl#5">dcl.decl</A>] paragraph 5,</P>

<BLOCKQUOTE>

<P>The <I>type-id</I> in a <I>trailing-return-type</I> includes the longest
possible sequence of <I>abstract-declarator</I>s. [<I>Note:</I> This
resolves the ambiguous binding of array and function
declarators. [<I>Example:</I>
</P>

<PRE>
  auto f()-&gt;int(*)[4]; //<SPAN CLASS="cmnt"> function returning a pointer to array[4] of </SPAN>int
                       //<SPAN CLASS="cmnt"> not function returning array[4] of pointer to </SPAN>int
</PRE>

<P>&#8212;<I>end example</I>] &#8212;<I>end note</I>]</P>

</BLOCKQUOTE>

<P>However, the grammar has changed since that rule and example were
added; because <I>trailing-return-type</I> can only appear at the top
level, there is no longer any potential ambiguity.</P>

<P><B>Proposed resolution (September, 2015):</B></P>

<P>Delete 9.3 [<A href="https://wg21.link/dcl.decl#5">dcl.decl</A>] paragraph 5:</P>

<BLOCKQUOTE>

<P><DEL>The optional <I>attribute-specifier-seq</I> in
a <I>trailing-return-type</I> appertains to the indicated return
type. The <I>type-id</I> in a <I>trailing-return-type</I> includes the
longest possible sequence of <I>abstract-declarator</I>s. [<I>Note:</I>
This resolves the ambiguous binding of array and function
declarators. [<I>Example:</I></DEL></P>

<PRE>
<DEL>  auto f()-&gt;int(*)[4]; //<SPAN CLASS="cmnt"> function returning a pointer to array[4] of </SPAN>int
                       //<SPAN CLASS="cmnt"> not function returning array[4] of pointer to </SPAN>int</DEL>
</PRE>

<P><DEL>&#8212;<I>end example</I>] &#8212;<I>end note</I>]</DEL></P>

</BLOCKQUOTE>

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