Re: Static vs dynamic evaluation anomaly?

[Simon Wright <simon.j.wright@mac.com>]

"Adam Beneschan" <adam@irvine.com> writes:

> On Feb 7, 10:27 am, "Jeffrey R. Carter" <jrcar...@acm.org> wrote:
>> Adam Beneschan wrote:
>>
>> > Yes, it does make a difference.  It appears that I'm using version
>> > 4.0.0.  When I use -gnato, I get the correct results; when I use -
>> > gnatp, or no flag, I get incorrect results (Text_IO displays values
>> > greater than 63, same as what Matt was seeing).
>>
>> This is a known issue. GNAT is not Ada without -gnato and -fstack-check.
>
> Seems like a pretty lame excuse, though.  Ada does have a Suppress
> pragma to suppress checks; as I understand the documentation, omitting
> -gnato causes certain checks not to be performed, and using -gnatp
> causes even more checks not to be performed, so the result should be
> more or less equivalent to using Suppress.  So it probably isn't
> accurate to say that GNAT isn't Ada in that case, but that's perhaps a
> matter of semantics.  In any case, though, using Suppress, or not
> using -gnato, or using -gnatp, shouldn't produce *different* results.
> The most I would expect is that the behavior would be different in
> cases where an exception would be raised if the check were performed---
> but I would not expect different behavior in a case where *no*
> exception is raised.  And in this case, no exception is raised---the
> Put is outputting different values.  So I still think this is a bug
> that needs to be fixed.  The current behavior (assuming that 4.1.1-22
> behaves the same as 4.0.0) isn't reasonable.

-gnato makes GNAT check for integer overflow, so it is at least in the
 right area!

I must say that I would have expected to get unsigned behaviour
independent of -gnato, though (and don't forget the RTL isn't getting
recompiled).

Similar results with GNAT-GPL-2006 on G4 Mac, BTW.