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    CWG Issue 738</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="738"></A><H4>738.
  
<TT>constexpr</TT> not permitted by the syntax of constructor declarations
</H4>
<B>Section: </B>11.4.5&#160; [<A href="https://wg21.link/class.ctor">class.ctor</A>]
 &#160;&#160;&#160;

 <B>Status: </B>C++11
 &#160;&#160;&#160;

 <B>Submitter: </B>James Widman
 &#160;&#160;&#160;

 <B>Date: </B>27 October, 2008<BR>


<P>[Voted into WP at August, 2010 meeting.]</P>



<P>According to 11.4.5 [<A href="https://wg21.link/class.ctor#1">class.ctor</A>] paragraph 1, only
<I>function-specifier</I>s are permitted in the declaration of a
constructor, and <TT>constexpr</TT> is not a <I>function-specifier</I>.
(See also <A HREF="263.html">issue 263</A>, in which the resolution
of a similar concern regarding the <TT>friend</TT> specifier did not
change 11.4.5 [<A href="https://wg21.link/class.ctor#1">class.ctor</A>] paragraph 1 but perhaps should have
done so.)</P>



<P><B>Proposed resolution (February, 2010):</B></P>

<P>Change 11.4.5 [<A href="https://wg21.link/class.ctor#1">class.ctor</A>] paragraph 1 as follows:</P>

<BLOCKQUOTE>

<P>Constructors do not have names.  A special declarator syntax
<DEL>using an optional sequence of <I>function-specifier</I>s
(9.2.3 [<A href="https://wg21.link/dcl.fct.spec">dcl.fct.spec</A>]) followed by the constructor's class
name followed by a parameter list</DEL> is used to declare or define
the constructor. <INS>The syntax uses</INS>
</P>

<UL>
<LI><P><INS>an optional <I>decl-specifier-seq</I> in which each
<I>decl-specifier</I> is either a <I>function-specifier</I> or
<TT>constexpr</TT>,</INS></P></LI>

<LI><P><INS>the constructor's class name, and</INS></P></LI>

<LI><P><INS>a parameter list</INS></P></LI>

</UL>

<P>
<INS>in that order.</INS> In such a declaration, optional
parentheses around the constructor class name are
ignored. [<I>Example:</I>...</P>

</BLOCKQUOTE>

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