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    CWG Issue 1561</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="1561"></A><H4>1561.
  
Aggregates with empty base classes
</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>CD4
 &#160;&#160;&#160;

 <B>Submitter: </B>Gabriel Dos Reis
 &#160;&#160;&#160;

 <B>Date: </B>2012-09-29<BR>


<P>[Accepted at the February, 2016 meeting as part of paper P0017R1.]</P>



<P>The definition of an aggregate class 9.5.2 [<A href="https://wg21.link/dcl.init.aggr">dcl.init.aggr</A>]
was originally intended to include only C-like classes because proper
C++ classes were expected to encapsulate data members and use
constructors for initialization.  Consequently, classes with bases
were excluded from being aggregates.</P>

<P>With the inclusion of aggregate initialization in list-initialization,
the consequence of this decision could be surprising, so it should be
reexamined.  For example,</P>

<PRE>
  struct A {
    int&amp; val;
  };

  struct B { };

  struct C : B {
    int&amp; val;
  };

  int main() {
    int i = 0;
    A a { i } ;         //<SPAN CLASS="cmnt"> #1</SPAN>
    C c { i } ;         //<SPAN CLASS="cmnt"> #2</SPAN>
    return 0;
  }
</PRE>

<P>it is not clear that there is a good rationale for #1 being
well-formed but #2 being ill-formed.</P>

<P><B>Rationale (October, 2012):</B></P>

<P>CWG felt that this language design question would be better
considered by EWG.</P>

<BR><BR>
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