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From: Bill Findlay <yaldnif.w@blueyonder.co.uk>
Newsgroups: comp.lang.ada
Subject: Re: Can't set executable stack size during compilation
Date: Thu, 05 Jan 2012 04:35:43 +0000
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Date: 2012-01-05T04:35:43+00:00
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On 05/01/2012 01:06, in article je2t32$20h$1@munin.nbi.dk, "Randy Brukardt"
<randy@rrsoftware.com> wrote:

> "Georg Bauhaus" <rm-host.bauhaus@maps.futureapps.de> wrote in message
> news:4f04c66c$0$6625$9b4e6d93@newsspool2.arcor-online.net...
>> On 1/4/12 6:22 PM, Bill Findlay wrote:
>>> On 04/01/2012 16:27, in article
>>> 4f047e0f$0$6582$9b4e6d93@newsspool3.arcor-online.net, "Georg Bauhaus"
>>> <rm.dash-bauhaus@futureapps.de>  wrote:
>>>> 
>>>> FWIW, I made a little test program; I think it is legal
>>> 
>>> It's not legal, of course: it fetches unassigned variables,
>> 
>> I had though that variables not assigned (uninitialized?)
>> won't be the subject of legality rules (and would otherwise
>> have to be rejected during compilation or post-compilation)?
>> 
>> If the program did perform I/O, its executions is likely
>> to have error, yes.
> 
> Formally, an "illegal" program is one that fails a Legality Rule, and those
> are checked at compile-time.
> 
> I suspect that Bill has being more informal ...

Yes, I wasn't being legalistic, just pragmatic. 8-)

> ... but even then, an Ada program can use an uninitialized value without the
> program being bad (erroneous); doing so might only be a bounded error and
> may not raise any exception at all depending on what is actually done.
> ("Invalid" values are allowed so long as they are not used to do array
> indexing and some other things.)

As it happens, when I ran it I got:

> /Users/wf/KDF9/emulation/Build: ./onstack
> 
> raised CONSTRAINT_ERROR : onstack.adb:19 range check failed

because my default GNAT switches ask it to (attempt to) check for uses of
uninitialized variables.

-- 
Bill Findlay
with blueyonder.co.uk;
use  surname & forename;