From 7760556420902752457 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,5e0145d162a6d1d6 X-Google-Attributes: gidf78e5,public From: "Walter W. Karas" Subject: Re: Why is granting friendship to a templ. parameter ill-formed? Date: 1998/03/11 Message-ID: <3505D38F.723F@ibm.net>#1/1 X-Deja-AN: 333017456 Content-Transfer-Encoding: 7bit References: <6dop9s$kq6$1@news.utu.fi> X-Original-Date: Tue, 10 Mar 1998 23:58:07 +0000 X-Notice: should be forwarded in their entirety to postmaster@ibm.net Content-Type: text/plain; charset=us-ascii X-Trace: 11 Mar 1998 04:14:31 GMT, 129.37.129.34 Organization: IBM.NET X-Auth: PGPMoose V1.1 PGP comp.std.c++ iQBFAgUANQa93OEDnX0m9pzZAQGFzwF/eaRTnfjdplMRX07wcJPgmiLYpYQlC/Do KtoFEbd10/xNrfL2a8Ba7H9Dhm5i77GM =OhJU MIME-Version: 1.0 Reply-To: wkaras@ibm.net Newsgroups: comp.std.c++ Isn't this one of those chicken-and-egg kind of things? Consider this code: template class X { ... }; class A { X xa; // error! can only use refs./ptrs to A }; // before done declaring A If the parameter T is a friend of X, wouldn't this lead to a forward reference like the one above? I guess you could only refer to X in non-inline member functions. That's getting into some pretty fine distinctions though. Jaakko =?UNKNOWN-8BIT?Q?J=E4rvi?= wrote: > > Hi, > > Why is this ill-formed? > > template class X { friend class T; ... > > It is clearly stated in the standard (below a clip from CD2), but what is > the reason behind it. > > /Jaakko > > 7.1.5.3 Elaborated type specifiers [dcl.type.elab] > ... > 2 ... > If the identifier (my addition: in friend class identifier) resolves to a > typedef-name or a tem- > plate type-parameter, the elaborated-type-specifier is ill-formed. > [Note: this implies that, within a class template with a template > type-parameter T, the declaration friend class T; > is ill-formed. ] > --- [ comp.std.c++ is moderated. To submit articles, try just posting with ] [ your news-reader. If that fails, use mailto:std-c++@ncar.ucar.edu ] [ --- Please see the FAQ before posting. --- ] [ FAQ: http://reality.sgi.com/austern_mti/std-c++/faq.html ]