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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: Contracted exceptions for Ada
Newsgroups: comp.lang.ada
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Date: Sun, 9 Dec 2007 18:36:54 +0100
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Date: 2007-12-09T18:36:57+01:00
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On Sun, 09 Dec 2007 16:11:13 +0100, Martin Krischik wrote:

> Dmitry A. Kazakov wrote:
> 
>> (Maybe a wild guess, but this could save Ariane V. A program assumed
>> Constraint_Error exception free was recompiled for the hardware where that
>> was not the case.)
> 
> My understanding is that the system was brought down by an unexpected
> hardware exception - i.E. one which the CPU's floating point unit
> generated.

Yes, and that would be detected by the compiler:

   function Integer (X : Float) return Integer;

which was contracted as exception-free on one platform will not be on
another. So the compiler would reject either its implementation that raises
Constraint_Error or else its use contracted as Constraint_Error-free. So
the idea.

(Contracted exceptions would mean a damn LOT of work for the compiler
vendors.)

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