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    CWG Issue 2242</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="2242"></A><H4>2242.
  
ODR violation with constant initialization possibly omitted
</H4>
<B>Section: </B>6.3&#160; [<A href="https://wg21.link/basic.def.odr">basic.def.odr</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++23
 &#160;&#160;&#160;

 <B>Submitter: </B>Hubert Tong
 &#160;&#160;&#160;

 <B>Date: </B>2016-03-05<BR><BR>


<A href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2720r0.pdf#US5-033">P2720R0 comment
  US&#160;5-033<BR></A>

<P>[Accepted as a DR at the November, 2022 meeting.]</P>

<P>Consider the following example:</P>

<PRE>
  //<SPAN CLASS="cmnt"> tu1.cpp</SPAN>
  extern const int a = 1;
  inline auto f() {
    static const int b = a;
    struct A { auto operator()() { return &amp;b; } } a;
    return a;
  }

  //<SPAN CLASS="cmnt"> tu2.cpp</SPAN>
  extern const int a;
  inline auto f() {
    static const int b = a;
    struct A { auto operator()() { return &amp;b; } } a;
    return a;
  }
  int main() {
    return *decltype(f())()();
  }
</PRE>

<P>Here, <TT>b</TT> may or may not have constant initialization.
This example should be an ODR violation.</P>

<P>(Split off from <A HREF="2123.html">issue 2123</A>.)</P>

<P><B>Proposed resolution (approved by CWG 2022-11-11):</B></P>

<P>Insert after 6.3 [<A href="https://wg21.link/basic.def.odr#14.7">basic.def.odr</A>] bullet 14.7 as follows:</P>

<UL>

<LI>...</LI>

<LI>In each such definition, corresponding entities shall
have the same language linkage.
</LI>

<LI><INS>In each such definition, const objects with static or thread
storage duration shall be constant-initialized if the object is
constant-initialized in any such definition.</INS></LI>

<LI>...</LI>

</UL>

<BR><BR>
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