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=-1.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM autolearn=unavailable autolearn_force=no version=3.4.4 X-Received: by 10.66.66.66 with SMTP id d2mr30513433pat.5.1434286129705; Sun, 14 Jun 2015 05:48:49 -0700 (PDT) X-Received: by 10.140.23.50 with SMTP id 47mr326375qgo.24.1434286129442; Sun, 14 Jun 2015 05:48:49 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!feeder.eternal-september.org!news.glorb.com!h15no2625318igd.0!news-out.google.com!k20ni1696qgd.0!nntp.google.com!z60no1152180qgd.1!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Sun, 14 Jun 2015 05:48:49 -0700 (PDT) In-Reply-To: <87k2v6oe6q.fsf@adaheads.sparre-andersen.dk> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=50.111.130.209; posting-account=Ies7ywoAAACcdHZMiIRy0M84lcJvfxwg NNTP-Posting-Host: 50.111.130.209 References: <4f4cd4b1-0a6d-441b-a4f7-98add70e4e1e@googlegroups.com> <87k2v6oe6q.fsf@adaheads.sparre-andersen.dk> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: <33d878fa-5997-4631-b9d6-97d15f2f53c0@googlegroups.com> Subject: Re: Is this a bug in my code or the compiler? From: brbarkstrom@gmail.com Injection-Date: Sun, 14 Jun 2015 12:48:49 +0000 Content-Type: text/plain; charset=ISO-8859-1 Xref: news.eternal-september.org comp.lang.ada:26320 Date: 2015-06-14T05:48:49-07:00 List-Id: Oddly, the June 2015 issue of the Comm. ACM showed up on the same day I noted this thread. That issue contains Leslie Lamport's 2013 Turing Prize lecture Lamport, L., 2015: The Computer Science of Concurrency: The Early Years, CACM, Vol. 58, No. 6, pp. 71-76. The paper is reasonably readable if you don't mind a bit of math. It seems to me that David's program has instances that fall into problems that require mutual exclusion, which Lamport discusses in a fair amount of detail. As he comments concurrency problems are subtle and complex - and hard to solve correctly. I'm not sure whether it's fair to expect the compiler to be able to deal by itself with a problem that might involve an underspecified set of preconditions. Lamport might suggest that it needs a mathematical specification of the type he sets up in his TLA+ language (see ). In the Ada world, this might be one of the targets of SPARK. Bruce B.