From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=0.2 required=5.0 tests=AC_FROM_MANY_DOTS,BAYES_00, XPRIO_SHORT_SUBJ autolearn=no autolearn_force=no version=3.4.4 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: 103376,78b2880bc7e78e39 X-Google-Attributes: gid103376,public X-Google-ArrivalTime: 2001-03-20 15:26:09 PST Path: supernews.google.com!sn-xit-03!supernews.com!freenix!isdnet!psinet-france!psiuk-f4!psiuk-p4!uknet!psiuk-n!news.pace.co.uk!nh.pace.co.uk!not-for-mail From: "Marin David Condic" Newsgroups: comp.lang.ada Subject: Re: RISC Date: Tue, 20 Mar 2001 18:10:56 -0500 Organization: Posted on a server owned by Pace Micro Technology plc Message-ID: <998o2h$sa2$1@nh.pace.co.uk> References: <98qumf$5sf$1@nh.pace.co.uk> <98r4g1$7r1$1@nh.pace.co.uk> <3ab1d090$1@pull.gecm.com><98t8la$rc$1@nh.pace.co.uk> <3ab72c8f$1@pull.gecm.com><997pq4$i35$1@nh.pace.co.uk> <3ab79ade$1@pull.gecm.com><998ctp$ond$1@nh.pace.co.uk> NNTP-Posting-Host: 136.170.200.133 X-Trace: nh.pace.co.uk 985129873 28994 136.170.200.133 (20 Mar 2001 23:11:13 GMT) X-Complaints-To: newsmaster@pace.co.uk NNTP-Posting-Date: 20 Mar 2001 23:11:13 GMT X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.50.4522.1200 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4522.1200 Xref: supernews.google.com comp.lang.ada:5945 Date: 2001-03-20T23:11:13+00:00 List-Id: Sounds reasonable to me. I'd assume that the minute the standard says "erroneous" I could safely expect that the compiler might make monkeys fly from my serial port and this would be "legal" behavior. Hence I'd have to "Boldly Go Where No Man Has Gone Before" and figure out what behavior I get from *my* specific compiler in *my* environment and decide how far to trust it. I don't believe that every program has to be 100% portable, safe or bug-free. If I *know* I'm stepping outside the bounds of normally acceptable programmer conduct and totally beyond the walls of any LRM/ARM protection rules, then from that point on, I'm working closely with my compiler documentation, the vendor, the assembly output, etc., and isolating that to some narrow part of the system. Overlays would fall in that category - they ought to be sufficiently painful to remind you that what you are doing is dangerous, but should remain possible in an implementation dependent manner. (There really aren't many excuses for it - but there are a few...:-) In other words: Never get out of the boat. Not unless you're ready to go all the way. MDC -- Marin David Condic Senior Software Engineer Pace Micro Technology Americas www.pacemicro.com Enabling the digital revolution e-Mail: marin.condic@pacemicro.com Web: http://www.mcondic.com/ "Robert A Duff" wrote in message news:wcck85koyz5.fsf@world.std.com... > Erroneous means that, but it also means that your program can do > absolutely anything, including wipe out your disk or (much worse) work > properly until you port it or turn on the optimizer or upgrade your > compiler. > > The "erroneous" rule about overlays was removed from Ada 95 quite > deliberately, because it was recognized that there are (rare) > circumstances where it makes sense to use overlays. And because we > weren't entirely sure what "overlay" means in a formal sense. > > Most of the remaining rules about "erroneous" are there for good reason: > eg, an optimizing compiler really might do something very surprising, > causing subtle bugs that occur only rarely. > > And note that rare bugs are the ones that matter. A bug that occurs the > first time you run the program will be found right away, and fixed. A > rare bug might escape to customers. > > - Bob