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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: A smaller self contained test case. Was: Compiler Bug or what I'm
 doing wrong?
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Date: Sat, 24 Jun 2006 13:46:42 +0200
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Date: 2006-06-24T13:46:42+02:00
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On 23 Jun 2006 11:55:23 +0200, M E Leypold wrote:

> I'm attaching a smaller (and now self contained test case!) for the
> SIGSEGV whil reading/writing varaint records which I wrote about
> earlier.
> 
> Some data:
> 
>  1. Gnat 3.15p on Debian Sarge.
>  2. Running the attached program wil result in a SIGSEGV in a finalizer.
> 
> I'm also attaching a short backtrace.

Well, it looks like a bug to me.

ARM 13.13.2 (9) reads:

   "If T is a discriminated type, discriminants are included only if they
have defaults."

which assumes that if they have, then 'Write/'Read should handle them
properly. When the discriminant is set to false before making 'Read, the
program works as expected.

The problem is essentially:

type Foo (C : Boolean := True) is ...;

X : Foo (False);
...
Foo'Write (S, X);


Y : Foo (True);
...
Foo'Read (S, Y); -- Boom

Any language lawyers, here?

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de