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    CWG Issue 1477</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="1477"></A><H4>1477.
  
Definition of a <TT>friend</TT> outside its namespace
</H4>
<B>Section: </B>_N4868_.9.8.2.3&#160; [<A href="https://wg21.link/namespace.memdef">namespace.memdef</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD3
 &#160;&#160;&#160;

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

 <B>Date: </B>2012-03-09<BR>


<P>[Moved to DR at the April, 2013 meeting.]</P>

<P>According to _N4868_.9.8.2.3 [<A href="https://wg21.link/namespace.memdef#3">namespace.memdef</A>] paragraph 3,</P>

<BLOCKQUOTE>

Every name first declared in a namespace is a member of that
namespace. If a <TT>friend</TT> declaration in a non-local class first
declares a class or function<SUP>95</SUP> the friend class or function
is a member of the innermost enclosing namespace. The name of the
friend is not found by unqualified lookup (6.5.3 [<A href="https://wg21.link/basic.lookup.unqual">basic.lookup.unqual</A>])
or by qualified lookup (6.5.5 [<A href="https://wg21.link/basic.lookup.qual">basic.lookup.qual</A>]) until a matching
declaration is provided in that namespace scope (either before or
after the class definition granting friendship).

</BLOCKQUOTE>

<P>Taken literally, that would mean the following example is
ill-formed:</P>

<PRE>
  namespace N {
    struct A {
      friend int f();
    };
  }
  int N::f() { return 0; }
  int i = N::f();    //<SPAN CLASS="cmnt"> ill-formed: </SPAN>N::f<SPAN CLASS="cmnt"> not found</SPAN>
</PRE>

<P>because the definition of <TT>N::f</TT> appears in global scope
rather than in namespace scope.</P>

<P><B>Proposed resolution (October, 2012):</B></P>

<P>Change _N4868_.9.8.2.3 [<A href="https://wg21.link/namespace.memdef#3">namespace.memdef</A>] paragraph 3 as follows:</P>

<BLOCKQUOTE>

Every name first declared in a namespace is a member of that
namespace. If a <TT>friend</TT> declaration in a non-local class first
declares a class or function<SUP>95</SUP> the friend class or function
is a member of the innermost enclosing namespace. <DEL>The name of the
friend is not found by</DEL> <INS>The <TT>friend</TT> declaration does
not by itself make the name visible to</INS> unqualified lookup
(6.5.3 [<A href="https://wg21.link/basic.lookup.unqual">basic.lookup.unqual</A>]) or <DEL>by</DEL> qualified lookup
(6.5.5 [<A href="https://wg21.link/basic.lookup.qual">basic.lookup.qual</A>])<INS>. [<I>Note:</I> The name of the
friend will be visible in its namespace if</INS> <DEL>until</DEL> a
matching declaration is provided <DEL>in that</DEL> <INS>at</INS>
namespace scope (either before or after the class definition granting
friendship). <INS>&#8212;<I>end note</I>]</INS> If a friend function
is called...

</BLOCKQUOTE>

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