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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: How to compile Barnes' examples from his book using GNAT
Date: Mon, 7 Dec 2015 20:01:22 -0600
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Xref: news.eternal-september.org comp.lang.ada:28697
Date: 2015-12-07T20:01:22-06:00
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"Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message 
news:n42cuc$nqs$1@dont-email.me...
> On 12/06/2015 02:21 PM, Pascal Obry wrote:
>>
>>> Almost. However, with no options, GNAT is not an Ada compiler. It
>>> doesn't insert
>>> integer-overflow checks,
>>
>> Recent GNAT versions have overflow on by default.
>
> That's good. When I had checked not too long ago, it was still off by 
> default.
>
>>> stack-overflow checks, assertion checks, pre- and
>>> post-condition checks, predicate checks, or invariant checks.
>>
>> The assertions and aspects checks are optional for an Ada compiler and
>> can be turned on and off.
>
> True, but examples from the book intended to demonstrate the use of these
> features may not behave as described if they are not turned on.

I would guess that most people starting out would expect that the default 
would be for them to be on. I got caught by it writing ACATS tests. The main 
reason the language doesn't say is that we didn't want to change the 
behavior of existing compilers (many of which had pragma Assert when it was 
added to the language). But that probably is the wrong choice for 
preconditions, predicates, and so on.

                            Randy.