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    CWG Issue 491</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="491"></A><H4>491.
  
Initializers for empty-class aggregrate members
</H4>
<B>Section: </B>9.5.2&#160; [<A href="https://wg21.link/dcl.init.aggr">dcl.init.aggr</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Nathan Sidwell
 &#160;&#160;&#160;

 <B>Date: </B>15 Dec 2004<BR>


<P>[Voted into WP at April, 2007 meeting.]</P>

<P>The current wording of 9.5.2 [<A href="https://wg21.link/dcl.init.aggr">dcl.init.aggr</A>] paragraph
8 requires that</P>

<BLOCKQUOTE>

An <I>initializer</I> for an aggregate member that is an empty class
shall have the form of an empty initializer-list <TT>{}</TT>.

</BLOCKQUOTE>

<P>This is overly constraining.  There is no reason that the
following should be ill-formed:</P>

<PRE>
    struct S { };
    S s;
    S arr[1] = { s };
</PRE>

<P>
<U>Mike Miller</U>: The wording of 9.5.2 [<A href="https://wg21.link/dcl.init.aggr#8">dcl.init.aggr</A>] paragraph 8 is unclear.  &#8220;An aggregate
member&#8221; would most naturally mean &#8220;a member of an
aggregate.&#8221; In context, however, I think it must mean
&#8220;a member [of an aggregate] that is an aggregate&#8221;,
that is, a subaggregate.  Members of aggregates need not
themselves be aggregates (cf paragraph 13 and 11.9.2 [<A href="https://wg21.link/class.expl.init">class.expl.init</A>]); it cannot be the case that an object of an
empty class with a user-declared constructor must be initialized
with <TT>{}</TT> when it is a member of an aggregate.  This
wording should be clarified, regardless of the decision on
Nathan's point.</P>

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

<P>This issue is resolved by the resolution of
<A HREF="413.html">issue 413</A>.</P>

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