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    CWG Issue 2379</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="2379"></A><H4>2379.
  
Missing prohibition against <TT>constexpr</TT> in <TT>friend</TT> declaration
</H4>
<B>Section: </B>13.7.5&#160; [<A href="https://wg21.link/temp.friend">temp.friend</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD5
 &#160;&#160;&#160;

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

 <B>Date: </B>2018-06-14<BR>


<P>[Accepted as a DR at the February, 2019 meeting.]</P>

<P>According to 13.7.5 [<A href="https://wg21.link/temp.friend#8">temp.friend</A>] paragraph 8,</P>

<BLOCKQUOTE>

When a friend declaration refers to a specialization of a function
template, the function parameter declarations shall not include default
arguments, nor shall the inline specifier be used in such a declaration.

</BLOCKQUOTE>

<P>Presumably this should also include the <TT>constexpr</TT>
specifier.</P>

<P><B>Notes from the December, 2018 teleconference:</B></P>

<P>This should also cover the newly-added <TT>consteval</TT>
specifier.</P>

<P><B>Proposed resolution (February, 2019):</B></P>

<P>Change 13.7.5 [<A href="https://wg21.link/temp.friend#8">temp.friend</A>] paragraph 8 as follows:</P>

<BLOCKQUOTE>

When a friend declaration refers to a specialization of a
function template, the function parameter declarations shall
not include default arguments, nor shall the <DEL>inline
specifier</DEL> <INS><TT>inline</TT>, <TT>constexpr</TT>,
or <TT>consteval</TT> specifiers</INS> be used in such a
declaration.

</BLOCKQUOTE>

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