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    CWG Issue 2099</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="2099"></A><H4>2099.
  
Inferring the bound of an array static data member
</H4>
<B>Section: </B>9.3.4.5&#160; [<A href="https://wg21.link/dcl.array">dcl.array</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Richard Smith
 &#160;&#160;&#160;

 <B>Date: </B>2015-03-15<BR>


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



<P>According to 9.3.4.5 [<A href="https://wg21.link/dcl.array#3">dcl.array</A>] paragraph 3,</P>

<BLOCKQUOTE>

An array bound may also be omitted when the declarator is
followed by an <I>initializer</I> (9.5 [<A href="https://wg21.link/dcl.init">dcl.init</A>]). In
this case the bound is calculated from the number of initial
elements...

</BLOCKQUOTE>

<P>However, the grammar for <I>member-declarator</I> uses
<I>brace-or-equal-initializer</I>, not <I>initializer</I>, so
the following is ill-formed:</P>

<PRE>
  struct X {
    static constexpr int arr[] = { 1, 2, 3 };
  };
</PRE>

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

<P>Change 9.3.4.5 [<A href="https://wg21.link/dcl.array#3">dcl.array</A>] paragraph 3 as follows:</P>

<BLOCKQUOTE>

...An array bound may also be omitted when the declarator is followed by an
<I>initializer</I> (9.5 [<A href="https://wg21.link/dcl.init">dcl.init</A>]) <INS>or when a declarator for
a static data member is followed by a <I>brace-or-equal-initializer</I>
(11.4 [<A href="https://wg21.link/class.mem">class.mem</A>])</INS>. In <DEL>this case</DEL> <INS>both
cases</INS> the bound is calculated from the number of initial elements...

</BLOCKQUOTE>

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