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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Simple loop with a strange output
Date: Fri, 24 May 2013 08:21:59 +0100
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Date: 2013-05-24T08:21:59+01:00
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"Randy Brukardt" <randy@rrsoftware.com> writes:

> "Simon Wright" <simon@pushface.org> wrote in message 
> news:lyppwh8x9y.fsf@pushface.org...
>> Luca Cappelletti <luca.cappelletti@gmail.com> writes:
>>
>>> do you know why the overflow checking is off by default?
>>
>> The explanation is here:
>> http://gcc.gnu.org/onlinedocs/gnat_ugn_unw/Controlling-Run_002dTime-Checks.html#index-g_t_0040option_007b_002dgnato_007d-_0028_0040command_007bgcc_007d_0029-595
>>
>> or here, if that link got broken: http://goo.gl/ffIjp
>
> That's the official line, but I think if you asked most people at
> AdaCore today, they'd tell you that it was a mistake.
>
> But mistakes like this one aren't really fixable, because of all of
> the existing code that would be at risk of breaking if they changed
> the default.  (That code would technically be wrong, but I doubt that
> would be much consolation if it meant that the train refused to stop.)
>
> This sort of thing is going to happen in any compiler that's been
> around a while. There are certainly defaults in Janus/Ada that I
> wouldn't make the default today, but breaking existing projects isn't
> really an option, so such changes hardly ever are made.

And most of us would agree that it was a mistake, too.

All my projects (free, and the ones I used to be paid for) use -gnato by
default. They don't use -fstack-check, because it wasn't reliable when I
was working out the project settings (and I could have really used it
when I needed a 500K stack to process some XML!).

I seriously doubt that any project where there was a possibility of a
train failing to stop would do something as risky as changing the
compiler without a thorough risk analysis. I wasn't allowed to, and
there were no trains involved (just point-defence missiles!)