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=ham
	autolearn_force=no version=3.4.4
X-Google-Thread: a07f3367d7,5d4ade2fd8fd67c6
X-Google-Attributes: gida07f3367d7,public,usenet
X-Google-NewGroupId: yes
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news3.google.com!feeder.news-service.com!easy.in-chemnitz.de!feeder.erje.net!nuzba.szn.dk!news.jacob-sparre.dk!pnx.dk!jacob-sparre.dk!ada-dk.org!.POSTED!not-for-mail
From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Legit Warnings or not
Date: Fri, 22 Jul 2011 19:31:08 -0500
Organization: Jacob Sparre Andersen Research & Innovation
Message-ID: <j0d4og$qdh$1@munin.nbi.dk>
References: 
 <531193e0-3305-4292-9ed8-0176226c1d00@x12g2000yql.googlegroups.com>
 <j086nn$aau$1@tornado.tornevall.net> <j08sp2$8qi$2@dont-email.me>
 <3e8384ce-e18a-4d84-95d7-f4eb750b16c9@u6g2000prc.googlegroups.com>
 <wcc4o2fbpzs.fsf@shell01.TheWorld.com>
 <b760b2c4-b774-43b6-b29e-4882470be1f4@a2g2000prf.googlegroups.com>
NNTP-Posting-Host: static-69-95-181-76.mad.choiceone.net
X-Trace: munin.nbi.dk 1311381072 27057 69.95.181.76 (23 Jul 2011 00:31:12 GMT)
X-Complaints-To: news@jacob-sparre.dk
NNTP-Posting-Date: Sat, 23 Jul 2011 00:31:12 +0000 (UTC)
X-Priority: 3
X-MSMail-Priority: Normal
X-Newsreader: Microsoft Outlook Express 6.00.2900.5931
X-RFC2646: Format=Flowed; Original
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6109
Xref: g2news2.google.com comp.lang.ada:21278
Date: 2011-07-22T19:31:08-05:00
List-Id: <comp.lang.ada>

"Adam Beneschan" <adam@irvine.com> wrote in message 
news:b760b2c4-b774-43b6-b29e-4882470be1f4@a2g2000prf.googlegroups.com...
>On Jul 21, 8:41 am, Robert A Duff <bobd...@shell01.TheWorld.com>
>wrote:
>> Adam Beneschan <a...@irvine.com> writes:
>> > You don't have to allocate a whole new Warned_Person, just a new Name.
>>
>> Right. If you allocate a whole new Warned_Person, you can get
>> dangling pointers and dangling renamings. If I remember correctly,
>> the rules prevent renaming or 'Access of parts of Name (assuming
>> it has aliased parts).
>
>3.10.2(26), 8.5.1(5).  However, I think the language now says that
>'Access and rename of a component are OK if the discriminated object
>is known to be constrained; that means that the implementation has to
>be smart enough to know that it can't allocate a new Name in that case
>(when the entire record is assigned) but keep the same pointer and
>just copy over the data that it points to.

That's a good idea anyway, just because allocating and deallocating memory 
is expensive. We do that any time the component does not change size - which 
has the side-effect of working in any case that would be allowed by the 
mentioned rules.

                          Randy.


                                 -- Adam