From: bobduff@world.std.com (Robert A Duff)
Subject: Re: Finalization and Garbage Collection: a hole in the RM?
Date: 1996/09/06
Date: 1996-09-06T00:00:00+00:00 [thread overview]
Message-ID: <DxBJ4C.FJy@world.std.com> (raw)
In-Reply-To: mazzanti-0609960944120001@mac-mazz.iei.pi.cnr.it
In article <mazzanti-0609960944120001@mac-mazz.iei.pi.cnr.it>,
Franco Mazzanti <mazzanti@iei.pi.cnr.it> wrote:
>Other aspects, instead, give to implementations the freedom the change
>or extend the normal semantic model, or the freedom to complete some
>unspecified aspects of the normal semantic model with erroneousness.
>And these are the best candidates for potential erroneous executions.
>(e.g. M(14): The operations on "nonstandard integer types" or
Highly unlikely to be defined as erroneous.
> M(38): The consequences of violating limitations on Restrictions
> pragmas.)
Very well might be defined as erroneous.
>They are not many, I counted only 13 of them.
>[ M(4,10,14,15,21,38,42,44,52,58,77,81,85) ]
>
>A third group, finally, allows a function call to return an
>"implementation-defined" result [M(20,40,86,87,123,124,127,128,131)].
>(e.g. M(123): The result of a floating point arithmetic operation in
> overflow situations, when the Machine_Overflows attribute
> of the result type is False.
> or M(86) The result of the Task_Identification.Image attribute.)
>
>The erroneousness of the program might be affected if the implementation
>were allowed to return an "abnormal result".
>Is this possibility allowed by the RM, or the fact that some value
>MUST be returned, even if implementation-defined, can be seen as
>automatically ruling out the possibility or returning an abnormal
>value (which would probably be erroneous by itself).?
I think the impl-def result has to be a valid, non-abnormal value of the
type.
>In other words: can a function required to return a (implementation
>defined) result, directly cause an erroneous execution?
No, I don't think so.
- Bob
next prev parent reply other threads:[~1996-09-06 0:00 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
1996-09-06 0:00 Finalization and Garbage Collection: a hole in the RM? Franco Mazzanti
1996-09-06 0:00 ` Robert A Duff [this message]
1996-09-07 0:00 ` Robert Dewar
-- strict thread matches above, loose matches on Subject: below --
1996-09-09 0:00 Franco Mazzanti
1996-09-04 0:00 Franco Mazzanti
1996-09-08 0:00 ` Robert Dewar
1996-09-02 0:00 Franco Mazzanti
1996-09-03 0:00 ` Robert A Duff
1996-09-03 0:00 ` Robert Dewar
1996-08-30 0:00 Franco Mazzanti
1996-08-30 0:00 ` Robert A Duff
1996-08-26 0:00 Franco Mazzanti
1996-08-29 0:00 ` Robert A Duff
1996-08-29 0:00 ` Robert A Duff
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