From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail
From: Natasha Kerensikova <lithiumcat@instinctive.eu>
Newsgroups: comp.lang.ada
Subject: Re: How to get nice traceback with GNAT?
Date: Sat, 22 Nov 2014 09:45:16 +0000 (UTC)
Organization: A noiseless patient Spider
Message-ID: <slrnm70mph.nrc.lithiumcat@nat.rebma.instinctive.eu>
References: <slrnm6u97f.nrc.lithiumcat@nat.rebma.instinctive.eu>
 <m4ofsd$ans$1@loke.gir.dk>
Injection-Date: Sat, 22 Nov 2014 09:45:16 +0000 (UTC)
Injection-Info: mx02.eternal-september.org;
 posting-host="76a49b86bc3e16725b7cfca3d85cb4c8";
	logging-data="30559"; mail-complaints-to="abuse@eternal-september.org";
	posting-account="U2FsdGVkX1/5en27F2WHA48aDNtpe7Nf"
User-Agent: slrn/1.0.1 (FreeBSD)
Cancel-Lock: sha1:hv5nYcx2pwIEiknEFeiaMNm+FE8=
Xref: news.eternal-september.org comp.lang.ada:23635
Date: 2014-11-22T09:45:16+00:00
List-Id: <comp.lang.ada>

On 2014-11-21, Randy Brukardt <randy@rrsoftware.com> wrote:
> "Natasha Kerensikova" <lithiumcat@instinctive.eu> wrote in message 
> news:slrnm6u97f.nrc.lithiumcat@nat.rebma.instinctive.eu...
>> Hello,
>>
>> I happen to have found a situation in which symbolic traceback is a
>> great help, but I have been a bit surprise by the (lack of) support in
>> the platform to which I have access.
>
> There is no standard for traceback, you are totally at the mercy of your 
> compiler vendor.

Indeed I am, but I don't think portability in debugging is that
important: I only need a set of tools that work on the platform where
debugging is performed. So when dealing with portable/fundamental bugs,
I'm free to choose the platform where the best tools for that task are
available.

>>In Debian/kFreeBSD, with GNAT 4.6, it looks like the following, which is
>>what I consider as perfect:
>>> 0x7fa993 in asis.ada_environments.open at asis-ada_environments.adb:241
>>> 0x481a57 in adactl at adactl.adb:90
>>> 0x417029 in main at b~adactl.adb:817
>>> 0x8015a4347 in ?? at ??:0
>>> 0x41706e in <_start> at ??:0
>
> No, perfect is:
> ** Unhandled CONSTRAINT_ERROR
>    Index or Subtype out of bounds - Pos of Error Value = -1
> On Line Number 484 In J2TYPE_PROFILE_CHECKING.END_SPEC_AND_DO_DELAYED_THUNKS
> Called from line number 1914 In J2SEMANTIC_ROUTINES.SEMANTICS
> Called from line number 466 In JANUS2.SEMDRIVER
> Called from line number 527 In JANUS2

It might be nitpicking, but as far as the traceback (word I
unfortunately missed in the subject) you actually provide less
information: GNAT has function name, file name, line number, while yours
lacks the file name (might be easy to find out, but that's still a
mental overhead nonetheless).

As far as the exception message goes, I agree that yours is quite
impressive. I didn't mention it in the OP because I'm actually chasing
user exceptions (explicit raise statements), so I have the power to
improve the exception message. Compare to the traceback, which is to
tied to the compiler internals that a mere user has no power to improve
anything. I can't even guess what is going in GNAT to get so wildly
different outputs on different platforms.



Natasha