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=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,45a9122ddf5fcf5
X-Google-Attributes: gid103376,public
From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Rules for Representation of Subtypes
Date: 1996/09/30
Message-ID: <DyKCDB.IrI@world.std.com>#1/1
X-Deja-AN: 186300607
references: <mheaney-ya023080002209961353500001@news.ni.net>
 <1996Sep28.155354.1@eisner> <DyGwtp.Bs1@world.std.com>
 <1996Sep29.082143.1@eisner>
organization: The World Public Access UNIX, Brookline, MA
newsgroups: comp.lang.ada
Date: 1996-09-30T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <1996Sep29.082143.1@eisner>,
Larry Kilgallen <kilgallen@eisner.decus.org> wrote:
>But my X'valid should still work.  And compilers are not allowed to
>change the flow of a program.
>
>	X := my_unchecked_conversion(Y);
>
>	if X'valid

It depends on how you instantiated my_unchecked_conversion.  If you used
a constrained integer, such that some values of Y will produce
out-of-range results, then it's erroneous, and the 'Valid will *not*
work.  Hence, my advice to always unchecked_convert to types that match
the hardware.

- Bob