From 5157416585490161697 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,c42fc9ad8a4a8a45 X-Google-Attributes: gidf78e5,public X-Google-ArrivalTime: 2003-01-21 22:54:45 PST Path: archiver1.google.com!news1.google.com!newsfeed.stanford.edu!logbridge.uoregon.edu!kibo.news.demon.net!mutlu.news.demon.net!demon!mail2news.demon.co.uk!devnull From: rani_sharoni@hotmail.com ("Rani Sharoni") Newsgroups: comp.std.c++ Subject: Re: Lookup for operators in expressions 13.3.1.2 Date: Wed, 22 Jan 2003 06:54:42 +0000 (UTC) Lines: 60 Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: <3e2db167@news.microsoft.com> References: <86fzrnl8yj.fsf@Zorthluthik.foo> X-Trace: mail2news.demon.co.uk 1043218482 8520 10.0.0.1 (22 Jan 2003 06:54:42 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Wed, 22 Jan 2003 06:54:42 +0000 (UTC) X-Received: from mulga.cs.mu.oz.au ([128.250.1.22]) by news.demon.co.uk with esmtp (Exim 4.05) id 18bEmW-0002DH-00 for mail2news@news.news.demon.net; Wed, 22 Jan 2003 06:54:41 +0000 X-Received: by mulga.cs.mu.OZ.AU id RAA04729; Wed, 22 Jan 2003 17:54:35 +1100 (EST) X-Authentication-Warning: mulga.cs.mu.OZ.AU: fjh set sender to devnull@stump.algebra.com using -f X-Path: comp-std-cpp-robomod!not-for-mail X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-Delivered-To: std-c++@ncar.ucar.edu X-Newsgroups: comp.std.c++ X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 6.00.2800.1106 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Original-NNTP-Posting-Host: 172.27.67.48 X-OriginalArrivalTime: 21 Jan 2003 20:45:51.0288 (UTC) FILETIME=[15AB9B80:01C2C18E] X-Spam-Status: No, hits=-2.4 required=5.0 tests=FORGED_HOTMAIL_RCVD,PRIORITY_NO_NAME,QUOTED_EMAIL_TEXT, REFERENCES,SPAM_PHRASE_00_01 version=2.41 Xref: archiver1.google.com comp.std.c++:17375 "Graeme Prentice" wrote in message news:fbtp2vg13aabiknfdlstg23ed932dv0hfu@4ax.com... > [...] > I'm not sure I understand you. If the class definition is not visible > then it's an incomplete type so can't be looked up in the scope of the > class. For the following code, the Borland compiler gives a compile > time error (undefined structure c1), Comeau 4.3.0.1 gives a > catastrophic failure (seems to be a problem in the Borland backend, so > the "front end" probably thinks it's valid) and GCC 3.2 compiles with no > errors. If this code is intended to be valid, I think 13.3.1.2 should > say that if the class T1 is an incomplete type then the set of member > candidates is empty - or else it should say that T1 must be a complete > type. The way 13.3.1.2 is currently written leaves it open to > interpretation IMO. Since some compilers treat it as valid code, it's > probably best to allow an incomplete type, to avoid breaking existing > code, if nothing else. > > class c1; > extern c1 o1; > void operator<<( c1&, int ); > > int main() > { > o1 << 23; > } > I thought that the C++ standard should say that in contexts in which incomplete type is involved the program should not change its meaning if the type was complete but I found no evidence for such rule although it seems to be in the spirit of the ODR. For example: struct B {}; struct D; int f(void *); int f(B*); D *dp; int x1 = f(dp); // selects f(void*) struct D : B {}; int x2 = f(dp); // oops - selects f(B*); In general, lookup might be change when type becomes complete. I found few places where the rule I mentioned is explicitly specified, For example: 5.3.1/4 - classes that declares operator&() 14.3.3/2 - visibility of partial specialization (another form of completeness) Rani --- [ 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://www.jamesd.demon.co.uk/csc/faq.html ]