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    CWG Issue 497</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="497"></A><H4>497.
  
Missing required initialization in example
</H4>
<B>Section: </B>7.6.4&#160; [<A href="https://wg21.link/expr.mptr.oper">expr.mptr.oper</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Giovanni Bajo
 &#160;&#160;&#160;

 <B>Date: </B>03 Jan 2005<BR>


<P>[Voted into WP at October 2005 meeting.]</P>

<P>7.6.4 [<A href="https://wg21.link/expr.mptr.oper#5">expr.mptr.oper</A>] paragraph 5 contains the following
example:</P>

<PRE>
    struct S {
        mutable int i;
    };
    const S cs;
    int S::* pm = &amp;S::i;   // pm<SPAN CLASS="cmnt"> refers to mutable member </SPAN>S::i
    cs.*pm = 88;           // <SPAN CLASS="cmnt">ill-formed: </SPAN>cs<SPAN CLASS="cmnt"> is a const object</SPAN>
</PRE>

<P>The const object <TT>cs</TT> is not explicitly initialized,
and class <TT>S</TT> does not have a user-declared default
constructor.  This makes the code ill-formed as per
9.5 [<A href="https://wg21.link/dcl.init#9">dcl.init</A>] paragraph 9.</P>

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

<P>Change the example in 7.6.4 [<A href="https://wg21.link/expr.mptr.oper#5">expr.mptr.oper</A>] paragraph 5 to read
as follows:</P>

<PRE>
    struct S {
        <INS>S() : i(0) { }</INS>
        mutable int i;
    };
    <INS>void f()
    {</INS>
        const S cs;
        int S::* pm = &amp;S::i;   // pm<SPAN CLASS="cmnt"> refers to mutable member </SPAN>S::i
        cs.*pm = 88;           // <SPAN CLASS="cmnt">ill-formed: </SPAN>cs<SPAN CLASS="cmnt"> is a const object</SPAN>
    <INS>}</INS>
</PRE>

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