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From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Rules for Representation of Subtypes
Date: 1996/10/02
Message-ID: <DyntAq.6MK@world.std.com>#1/1
X-Deja-AN: 186736869
references: <mheaney-ya023080002209961353500001@news.ni.net>
 <1996Sep29.082143.1@eisner> <DyKCDB.IrI@world.std.com>
 <325155A5.2E50@lmtas.lmco.com>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-10-02T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <325155A5.2E50@lmtas.lmco.com>,
Ken Garlington  <garlingtonke@lmtas.lmco.com> wrote:
>I seem to remember some AI about using unchecked_conversion when the
>sizes of X and Y are different. Maybe it's compiler dependent, but I
>thought you were at least guaranteed that the unchecked_conversion of Y
>would _fit_ into the space allocated for X, although of course Y might
>be outside the range of X. In that case, X'Valid should work, shouldn't
>it?

No.  See 13.9.1(12).  Nothing, not even 'Valid, can be assumed to work,
if the execution is erroneous.

- Bob