<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<TITLE>
    CWG Issue 1006</TITLE>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<STYLE TYPE="text/css">
  INS { text-decoration:none; font-weight:bold; background-color:#A0FFA0 }
  .INS { text-decoration:none; background-color:#D0FFD0 }
  DEL { text-decoration:line-through; background-color:#FFA0A0 }
  .DEL { text-decoration:line-through; background-color: #FFD0D0 }
  @media (prefers-color-scheme: dark) {
    HTML { background-color:#202020; color:#f0f0f0; }
    A { color:#5bc0ff; }
    A:visited { color:#c6a8ff; }
    A:hover, a:focus { color:#afd7ff; }
    INS { background-color:#033a16; color:#aff5b4; }
    .INS { background-color: #033a16; }
    DEL { background-color:#67060c; color:#ffdcd7; }
    .DEL { background-color:#67060c; }
  }
  SPAN.cmnt { font-family:Times; font-style:italic }
</STYLE>
</HEAD>
<BODY>
<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="1006"></A><H4>1006.
  
<TT>std::nullptr_t</TT> as a non-type template parameter
</H4>
<B>Section: </B>13.2&#160; [<A href="https://wg21.link/temp.param">temp.param</A>]
 &#160;&#160;&#160;

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

 <B>Submitter: </B>Mike Miller
 &#160;&#160;&#160;

 <B>Date: </B>2009-11-20<BR>


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



<P>
<TT>std::nullptr_t</TT> is not currently allowed by
13.2 [<A href="https://wg21.link/temp.param#4">temp.param</A>] paragraph 4 to be used as the type of a
non-type template parameter.  However, this could arise for a
template with a non-type template parameter with a dependent type
in a template intended for use with pointers, e.g.,</P>

<PRE>
    template&lt;typename T, T t&gt; void f();
    ...
    f&lt;std::nullptr_t, nullptr&gt;();
</PRE>

<P>or in a case of delegation.</P>

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

<P>Change 13.2 [<A href="https://wg21.link/temp.param#4">temp.param</A>] paragraph 4 as follows:</P>

<BLOCKQUOTE>

<P>A non-type <I>template-parameter</I> shall have one of the following
(optionally <I>cv-qualified</I>) types:</P>

<UL>
<LI><P>integral or enumeration type,</P></LI>

<LI><P>pointer to object or pointer to function,</P></LI>

<LI><P>lvalue reference to object or lvalue reference to function,</P></LI>

<LI><P>pointer to member<DEL>.</DEL><INS>,</INS>
</P></LI>

<LI><P><INS><TT>std::nullptr_t</TT>.</INS></P></LI>

</UL>

</BLOCKQUOTE>

<BR><BR>
</BODY>
</HTML>
