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=-0.9 required=5.0 tests=BAYES_00,FORGED_GMAIL_RCVD, FREEMAIL_FROM autolearn=no autolearn_force=no version=3.4.4 X-Received: by 2002:a6b:e503:: with SMTP id y3-v6mr8578522ioc.32.1538417350712; Mon, 01 Oct 2018 11:09:10 -0700 (PDT) X-Received: by 2002:aca:fc85:: with SMTP id a127-v6mr191248oii.6.1538417350433; Mon, 01 Oct 2018 11:09:10 -0700 (PDT) Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!news.gegeweb.eu!gegeweb.org!usenet-fr.net!proxad.net!feeder1-2.proxad.net!209.85.166.216.MISMATCH!x98-v6no64326ita.0!news-out.google.com!n199-v6ni37itn.0!nntp.google.com!x188-v6no63842ite.0!postnews.google.com!glegroupsg2000goo.googlegroups.com!not-for-mail Newsgroups: comp.lang.ada Date: Mon, 1 Oct 2018 11:09:10 -0700 (PDT) In-Reply-To: <584564c2-9f64-4965-b045-535cdaf899c0@googlegroups.com> Complaints-To: groups-abuse@google.com Injection-Info: glegroupsg2000goo.googlegroups.com; posting-host=100.0.197.169; posting-account=PvmV9AoAAAD6m3XXwubwsbGwa7cDXv1N NNTP-Posting-Host: 100.0.197.169 References: <584564c2-9f64-4965-b045-535cdaf899c0@googlegroups.com> User-Agent: G2/1.0 MIME-Version: 1.0 Message-ID: Subject: Re: Why are Ada compilers difficult to write ? From: Tucker Taft Injection-Date: Mon, 01 Oct 2018 18:09:10 +0000 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Xref: reader02.eternal-september.org comp.lang.ada:54464 Date: 2018-10-01T11:09:10-07:00 List-Id: Perhaps the hardest aspect of getting an Ada compiler to pass all of the AC= ATS conformance tests is to correctly diagnose all errors, which includes b= oth compile-time error detection (the so-called "B" tests of the ACATS test= suite) and the run-time checks, which raise exceptions when some dynamic s= emantics rule of the language is violated (the so-called "C" tests of the A= CATS test suite). One of the great strengths of Ada compared to other languages is the strict= ness of the conformance test suite, and its attention to both correctly exe= cuting "good" tests but also correctly detecting compile-time or run-time p= roblems in "bad" tests. I remember many times when an implementor of an Ad= a compiler would announce that they were "almost done," only to discover th= at passing all of the B tests took another five person years of effort. I would presume that correctly implementing C++ is harder than Ada these da= ys, given that C++ seems to contain the union of all language features ever= invented for any language. But relative to C or Pascal, Ada and C++ are a= t least one order of magnitude harder, with exceptions, generic templates, = object-oriented programming, and finalization/destructors, as just a few of= the sources of compiler complexity.=20