From 8313011565058386141 X-Google-Thread: f78e5,1e6093a60facd084 X-Google-Attributes: gidf78e5,public X-Google-Language: ENGLISH,ASCII Path: g2news2.google.com!news4.google.com!border1.nntp.dca.giganews.com!nntp.giganews.com!newsfeed00.sul.t-online.de!t-online.de!newsfeed.icl.net!news-lond.gip.net!news-raspail.gip.net!news.gsl.net!gip.net!grolier!skynet.be!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!stump.algebra.com!devnull From: tommi.hoynalanmaa@iki.fi (=?ISO-8859-1?Q?Tommi_H=F6yn=E4l=E4nmaa?=) Newsgroups: comp.std.c++ Subject: Re: [Proposal] noreturn_t Date: Sun, 29 Oct 2006 01:06:49 GMT Organization: Saunalahti Customer Lines: 54 Sender: mail2news@demon.net Approved: fjh@cs.mu.oz.au (Fergus Henderson , moderator of comp.std.c++) Message-ID: References: <1161490402.699940.293180@b28g2000cwb.googlegroups.com> NNTP-Posting-Host: news.news.demon.net Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-Trace: news.demon.co.uk 1162084024 21239 158.152.254.254 (29 Oct 2006 01:07:04 GMT) X-Complaints-To: abuse@demon.net NNTP-Posting-Date: Sun, 29 Oct 2006 01:07:04 +0000 (UTC) X-Original-To: std-c++@mailman.ucar.edu X-Robomod: STUMP, ichudov@algebra.com (Igor Chudov) X-User-Agent: Thunderbird 1.5.0.7 (X11/20060922) X-MIME-Autoconverted: from 8bit to quoted-printable by mulga.csse.unimelb.edu.au id k9T16xM6014922 X-Virus-Scanned: amavisd-new at csse.unimelb.edu.au X-Path: comp-std-cpp-robomod!not-for-mail X-Received: (from fjh@localhost) by mulga.csse.unimelb.edu.au (8.13.6+Sun/8.13.6/Submit) id k9T16nQl014858; Sun, 29 Oct 2006 12:06:49 +1100 (EST) X-NNTP-Posting-Date: Sat, 28 Oct 2006 22:49:04 EEST X-Delivered-To: std-c++@mailman.ucar.edu X-Authentication-Warning: mulga.csse.unimelb.edu.au: fjh set sender to devnull@stump.algebra.com using -f X-Newsgroups: comp.std.c++ Xref: g2news2.google.com comp.std.c++:4235 Andrei Polushin kirjoitti: > I propose to add a special type, std::noreturn_t, to indicate that > function does never return. >=20 > Actually, some compilers have the similar feature, known as either > __declspec(noreturn) or __attribute__ ((noreturn)), but it is used > primarily for optimization purposes and does not affect language. This is a question about the execution flow and not about the result=20 type of a function. There would be no values whose type is noreturn_t. So "noreturn" should be an attribute of a function like the throw=20 specifications. "noreturn" and other attributes should be part of the type of the=20 function (i.e. function pointer type), not the type of the result value. BTW, there should also be attribute "pure" to indicate that a function=20 has no side effects. A pure function would not be allowed to call any=20 non-pure functions or to change global variables. GCC implements "pure"=20 and "const" attributes for pure functions. C++ should also have a standardized syntax for the (standard) function=20 attributes. Perhaps something like void myfunc(int a, char b) attributes(noreturn) A function with the pure attribute would be compatible with the=20 corresponding function type with or without the pure attribute. A=20 function without the pure attribute would not be compatible with the corresponding function type with the pure attribute. There could be another attribute "mustreturn" to indicate that a=20 function has to return. "mustreturn" and "noreturn" would be mutually=20 exclusive. Then - A function with neither of the return attributes would be compatible=20 with the corresponding function type with or without "noreturn" or=20 "mustreturn" attributes. - A function with "noreturn" attribute would not be compatible with the=20 corresponding function type with the "mustreturn" attribute. - A function with "mustreturn" attribute would not be compatible with=20 the corresponding function type with the "noreturn" attribute. --=20 Tommi H=F6yn=E4l=E4nmaa s=E4hk=F6posti / e-mail: tommi.hoynalanmaa@iki.fi kotisivu / homepage: http://www.iki.fi/tohoyn/ --- [ 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.comeaucomputing.com/csc/faq.html ]