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From: Robert A Duff <bobduff@world.std.com>
Subject: Re: Constraint checking of actuals passed to Attributes
Date: 2000/05/12
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Sender: bobduff@world.std.com (Robert A Duff)
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Date: 2000-05-12T00:00:00+00:00
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Ted Dennison <dennison@telepath.com> writes:

> But I still don't understand the logic behind making misuse of an
> overlay an "invalid" case rather than an "abonormal" (and thus
> erronious) case. Couldn't it cause the same -4 billion value to get
> placed into Y? The compiler would have no easy way to detect that the
> state has changed to "invalid". How do you enforce that the program
> "survives" this?

I'm not sure what you mean, here.  Could you post a specific example?
(Maybe you already did, but I've long since forgotten about it. ;-))

Certainly you can cause abnormal objects, and erroneousness, by certain
misuses of address clauses and unchecked conversions of access values,
both of which can be used to make overlays.

- Bob