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    CWG Issue 1397</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="1397"></A><H4>1397.
  
Class completeness in non-static data member initializers
</H4>
<B>Section: </B>11.4&#160; [<A href="https://wg21.link/class.mem">class.mem</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Jason Merrill
 &#160;&#160;&#160;

 <B>Date: </B>2011-09-23<BR>


<P>[Moved to DR at the November, 2014 meeting.]</P>



<P>In Bloomington there was general agreement that given a class
that uses non-static data member initializers, the
exception-specification for the default constructor depends on
whether those initializers are noexcept.  However, according to
11.4 [<A href="https://wg21.link/class.mem#2">class.mem</A>] paragraph 2, the class is regarded as
complete within the <I>brace-or-equal-initializer</I>s for
non-static data members.</P>

<P>This suggests that we need to finish processing the class
before parsing the NSDMI, but our direction on <A HREF="1351.html">issue 1351</A> suggests that we need to parse the
NSDMI in order to finish processing the class.  Can't have
both...</P>

<P><B>Additional note (March, 2013):</B></P>

<P>A specific example:</P>

<PRE>
  struct A {
    void *p = A{};
    operator void*() const { return nullptr; }
  };
</PRE>

<P>Perhaps the best way of addressing this would be to make it ill-formed
for a non-static data member initializer to use a defaulted constructor
of its class.</P>

<P>See also <A HREF="1360.html">issue 1360</A>.</P>

<P><B>Notes from the September, 2013 meeting:</B></P>

<P>One approach that might be considered would be to parse deferred
portions lazily, on demand, and then issue an error if this results in
a cycle.</P>

<P><B>Proposed resolution (February, 2014):</B></P>

<P>Change 11.4 [<A href="https://wg21.link/class.mem#4">class.mem</A>] paragraph 4 as follows:</P>

<BLOCKQUOTE>

A <I>brace-or-equal-initializer</I> shall appear only in the declaration of
a data member. (For static data members, see 11.4.9.3 [<A href="https://wg21.link/class.static.data">class.static.data</A>];
for non-static data members, see 11.9.3 [<A href="https://wg21.link/class.base.init">class.base.init</A>]). <INS>A
<I>brace-or-equal-initializer</I> for a non-static data member shall not
directly or indirectly cause the implicit definition of a defaulted
default constructor for the enclosing class or the
<I>exception-specification</I> of that constructor.</INS>

</BLOCKQUOTE>



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