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: 
 border1.nntp.dca3.giganews.com!border3.nntp.dca.giganews.com!border1.nntp.dca.giganews.com!nntp.giganews.com!goblin1!goblin.stu.neva.ru!eternal-september.org!feeder.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: GNAT GPL 2013 bug?
Date: Fri, 09 Aug 2013 19:25:57 +0100
Organization: A noiseless patient Spider
Message-ID: <lyli4araa2.fsf@pushface.org>
References: <19fr4wmxmen$.gjbias2fj461$.dlg@40tude.net>
 <b89f7b9a-1437-4e46-ace1-1355cc2a16c5@googlegroups.com>
 <hrkm713gcc7n$.mep6a9ijq09k.dlg@40tude.net>
 <72539e4c-dddd-40e4-82e8-14c4f2016ccc@googlegroups.com>
 <lypptmrgi0.fsf@pushface.org>
 <fe9f4149-1552-427a-96ed-a92d7ef679d5@googlegroups.com>
Mime-Version: 1.0
Content-Type: text/plain
Injection-Info: mx05.eternal-september.org;
 posting-host="ab63a21f76991e88ee5b3b5ea015b144";
 logging-data="18890"; mail-complaints-to="abuse@eternal-september.org";
 posting-account="U2FsdGVkX1/CVahxAiu+JKc5xTVUB3LEDGZ2DjI+Crs="
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (darwin)
Cancel-Lock: sha1:+FVUwWlwL5DFnBoM+9g1wqQeKKY=
 sha1:3YjcvW4X6LaMeplb/aRe6zI7TS0=
X-Original-Bytes: 2766
Xref: number.nntp.dca.giganews.com comp.lang.ada:182886
Date: 2013-08-09T19:25:57+01:00
List-Id: <comp.lang.ada>

Adam Beneschan <adambeneschan@aol.com> writes:

> On Friday, August 9, 2013 9:11:35 AM UTC-7, Simon Wright wrote:
>   
>> > In some of the examples in your later post (like the one where Q is
>> > private and the full type is a tagged record), there isn't a problem
>> > either, since the procedure isn't dispatching.
>> 
>> So when GNAT says, at the procedure call, that a null value isn't
>> allowed and that CE will be raised, it's wrong?
>
> I just tried it on a case with "type Q is private" [not tagged] and a
> full definition "type Q is tagged null record", and I didn't get a
> warning.  In the example you posted, GNAT is correct to display a
> warning, but your procedure *is* dispatching, and this situation isn't
> the same as the part of my post that you quoted.

I was talking about a slightly different case, corresponding to yours I
think:

   package Dmitry is
      type Q is private;
      procedure P (X : access Q) is null;
   private
      type Q is tagged null record;
   end Dmitry;
   with Dmitry; use Dmitry;
   procedure Test_Dmitry is
      Y : access Q;
   begin
      P (Y);                  ------ dmitry.ada:11
   end Test_Dmitry;

and get (GCC 4.8.1 and GNAT GPL 2013):

gnatmake test_dmitry.adb  -gnat12 -f
gcc -c -gnat12 test_dmitry.adb
dmitry.ada:9:04: warning: variable "Y" is read but never assigned
dmitry.ada:11:07: warning: null value not allowed here
dmitry.ada:11:07: warning: "Constraint_Error" will be raised at run time
gcc -c -gnat12 dmitry.ads
gnatbind -x test_dmitry.ali
gnatlink test_dmitry.ali