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    CWG Issue 1199</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="1199"></A><H4>1199.
  
Deleted constexpr functions
</H4>
<B>Section: </B>9.2.6&#160; [<A href="https://wg21.link/dcl.constexpr">dcl.constexpr</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Daniel Kr&#252;gler
 &#160;&#160;&#160;

 <B>Date: </B>2010-09-17<BR>


<P>[Voted into the WP at the March, 2011 meeting as part of paper N3277.]</P>



<P>The current requirements for constexpr functions do not permit a
deleted constexpr function because the definition does not consist of
a <I>compound-statement</I> containing just a <TT>return</TT>
statement.  However, it could be useful to allow this form in a
case where a single piece of code is used in multiple configurations,
in some of which the function is constexpr and others deleted;
having to update all declarations of the function to remove the
<TT>constexpr</TT> specifier is unnecessarily onerous.</P>

<P><B>Proposed resolution (January, 2011):</B></P>

<OL>
<LI><P>Change 9.2.6 [<A href="https://wg21.link/dcl.constexpr#3">dcl.constexpr</A>] paragraph 3 as follows:</P></LI>

<BLOCKQUOTE>

<UL>
<LI><P>...</P></LI>

<LI>
<P>its <I>function-body</I> shall be <INS><TT>= delete</TT>
or</INS> a <I>compound-statement</I> of the form</P>

<PRE>
  { return <I>expression</I> ; }
</PRE>

</LI>

<LI><P>...</P></LI>

</UL>

</BLOCKQUOTE>

<LI><P>Change 9.2.6 [<A href="https://wg21.link/dcl.constexpr#4">dcl.constexpr</A>] paragraph 4 as follows:</P></LI>

<BLOCKQUOTE>

<P>
<DEL>The definition of a <TT>constexpr</TT> constructor</DEL>
<INS>In the definition of a <TT>constexpr</TT> constructor, each of
the parameter types shall be a literal type or a reference to a
literal type.  In addition, either its <I>function-body</I> shall be
<TT>= delete</TT> or it</INS> shall satisfy the following
constraints:</P>

<UL>
<LI><P><DEL>each of its parameter types shall be a literal type or
a reference to literal type;</DEL></P></LI>

<LI><P>...</P></LI>

</UL>

</BLOCKQUOTE>

</OL>

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