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 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: Limited type in generic package causes double free or corruption Date: Wed, 28 Sep 2016 18:06:02 +0200 Organization: Aioe.org NNTP Server Message-ID: References: <374b0d79-541d-44d2-886e-dd41f8815914@googlegroups.com> NNTP-Posting-Host: 1YuCPr00zqg9zND3Lb27jw.user.gioia.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.3.0 X-Notice: Filtered by postfilter v. 0.8.2 Xref: news.eternal-september.org comp.lang.ada:31919 Date: 2016-09-28T18:06:02+02:00 List-Id: On 2016-09-28 15:25, onox wrote: > Shouldn't the compiler (GNAT GPL 2015) check that the type in the > generic formal parameter (package) is limited and forbid the copying > operation? No, limited return kludge (bug IMO) was introduced to Ada. > If I remove the "limited" keyword from the type, then the > program terminates without any errors. Limited return does not work well (and has no sense anyway). And you must decide about the semantics of "returning" a tree. It can be deep copy or shallow copy. In the latter case there should be a node reference counting schema deployed to clone updated nodes visible through several references. Either would prevent "corruption". -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de