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    CWG Issue 1712</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="1712"></A><H4>1712.
  
<TT>constexpr</TT> variable template declarations
</H4>
<B>Section: </B>9.2.6&#160; [<A href="https://wg21.link/dcl.constexpr">dcl.constexpr</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Richard Smith
 &#160;&#160;&#160;

 <B>Date: </B>2013-07-08<BR>


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



<P>According to 9.2.6 [<A href="https://wg21.link/dcl.constexpr#1">dcl.constexpr</A>] paragraph 1,</P>

<BLOCKQUOTE>

If any declaration of a function, function template, or variable template
has a <TT>constexpr</TT> specifier, then all its declarations shall contain
the <TT>constexpr</TT> specifier.

</BLOCKQUOTE>

<P>This requirement does not make sense applied to variable templates.
The <TT>constexpr</TT> specifier requires that there be an initializer,
and a variable template declaration with an initializer is a definition,
so there cannot be more than one declaration of a variable template
with the <TT>constexpr</TT> specifier.</P>

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

<P>Change 9.2.6 [<A href="https://wg21.link/dcl.constexpr#1">dcl.constexpr</A>] paragraph 1 as follows:</P>

<BLOCKQUOTE>

...If any declaration of a function<DEL>,</DEL> <INS>or</INS> function
template<DEL>, or variable template</DEL> has a <TT>constexpr</TT>
specifier, then all its declarations shall contain the <TT>constexpr</TT>
specifier. [<I>Note:</I>...

</BLOCKQUOTE>

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