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=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Thread: 103376,a9026b81108642ee
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news2.google.com!news.germany.com!newsfeed.utanet.at!newsfeed01.chello.at!newsfeed.arcor.de!newsspool3.arcor-online.net!news.arcor.de.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Address of an object
Newsgroups: comp.lang.ada
User-Agent: 40tude_Dialog/2.0.15.1
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Reply-To: mailbox@dmitry-kazakov.de
Organization: cbb software GmbH
References: <382nx7mt637x$.6hjqgb4zxzss.dlg@40tude.net>
 <u8xkkosk0.fsf@stephe-leake.org>
Date: Sat, 16 Sep 2006 19:06:18 +0200
Message-ID: <n03kqae9v6ah$.hjxa120hu8oq$.dlg@40tude.net>
NNTP-Posting-Date: 16 Sep 2006 19:06:02 CEST
NNTP-Posting-Host: 2aeb0b0d.newsspool4.arcor-online.net
X-Trace: 
 DXC=j]K:6FRn>kYE47KDAk81NW4IUK<Cl32<Q4Fo<]lROoRQFl8W>\BH3YROVf4a_6cY_UDNcfSJ;bb[UIRnRBaCd<M^3jnE^_h?^;XDUB0<hJn`j[
X-Complaints-To: usenet-abuse@arcor.de
Xref: g2news2.google.com comp.lang.ada:6616
Date: 2006-09-16T19:06:02+02:00
List-Id: <comp.lang.ada>

On Sat, 16 Sep 2006 09:21:51 -0400, Stephen Leake wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
> 
>> Both X'Address and Unchecked_Conversion of a pointer to X would not give
>> the true address of X (i.e. the address returned by Allocate of the
>> corresponding storage pool). For an array type, X'Address is the address of
>> the first element, the dope is out.
>>
>> Is there any better way 
> 
> A better way to do what?
> 
> What are you doing, that either X'Address or X'Access is wrong?

Both are. Do the following under GNAT:

type P is access String;
for P'Storage_Pool use My_Pool;

procedure Allocate (Pool : My_Pool; Addr : out Storage_Address; ...) is
begin
   ...
   Addr := A;
end Allocate;

P := new String'("abc");

Then compare A with P.all'Address. They will differ. A = P.all'Address - 8,
I guess. [ It is not yet another bug of GNAT, it is a proper behavior. ARM
explicitly requires this.]

See also my response to Adam.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de