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    CWG Issue 460</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="460"></A><H4>460.
  
Can a <I>using-declaration</I> name a namespace?
</H4>
<B>Section: </B>9.10&#160; [<A href="https://wg21.link/namespace.udecl">namespace.udecl</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD1
 &#160;&#160;&#160;

 <B>Submitter: </B>John Spicer
 &#160;&#160;&#160;

 <B>Date: </B>12 Feb 2004<BR>


<P>[Voted into WP at April 2005 meeting.]</P>

<P>Can a using-declaration be used to import a namespace?</P>
<PRE>
namespace my_namespace{
  namespace my_namespace2 {
    int function_of_my_name_space(){ return 2;}
  }
}

int main (){
  using  ::my_namespace::my_namespace2;
  return my_namespace2::function_of_my_name_space();
}
</PRE>
<P>Several popular compilers give an error on this, but there
doesn't seem to be anything in 9.10 [<A href="https://wg21.link/namespace.udecl">namespace.udecl</A>] that
prohibits it.  It should be noted that the user can get the same
effect by using a namespace alias:</P>
<PRE>
  namespace my_namespace2 = ::my_namespace::my_namespace2;
</PRE>

<P><B>Notes from the March 2004 meeting:</B></P>

<P>We agree that it should be an error.</P>

<P><B>Proposed resolution (October, 2004):</B></P>

<P>Add the following as a new paragraph after 9.10 [<A href="https://wg21.link/namespace.udecl#5">namespace.udecl</A>] paragraph 5:</P>

<BLOCKQUOTE>

A <I>using-declaration</I> shall not name a namespace;

</BLOCKQUOTE>

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