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Newsgroups: comp.lang.ada
Subject: Re: Is this definition legal?
References: <Vx33d.3580$d5.27722@newsb.telia.net>
From: Ludovic Brenta <ludovic.brenta@insalien.org>
Date: Sun, 19 Sep 2004 01:44:40 +0200
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Date: 2004-09-19T01:47:11+02:00
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Björn Persson writes:
> GCC-Gnat 3.4.0 is having serious problems with the definition of
> Character_Encoding below:

[elided]

> Gnat often crashes with a bug box on a reference to
> Character_Encoding. For example, when I declare a variable of this
> type I have to initialize it at the declaration to avoid a bug
> box. Also, the predefined "=" for Character_Encoding sometimes
> returns False for values that should be equal.
>
> Once when I converted a Character_Encoding to a
> Unified_Encoding_Record, the field OS was set to NT, even though
> This_OS = Linux. The next conversion raised Constraint_Error with
> the message "invalid data".

Whether or not your code is legal, a bug box is a bug.  I would be
interested in a short test case for each of your issues (one for the
bug box upon declaring a Character_Encoding without an initialiser;
one for the conversion that alters OS, and one where the conversions
raises Constraint_Error.

> My first question is: Is this definition of Character_Encoding legal
> and I should work around the problems until Gnat gets fixed, or is
> it illegal code that Gnat fails to reject, and I should find another
> way to do it?

Sorry, I don't know.  It seems okay to me at first glance, but I've
been wrong about such things before :)

-- 
Ludovic Brenta.