From mboxrd@z Thu Jan  1 00:00:00 1970
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From: bcf@ssd.ray.com (Felaco)
Subject: Renaming record discriminants.
Date: 1996/04/01
Message-ID: <Dp75Aq.B1o@ssd.ray.com>#1/1
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sender: news@ssd.ray.com (Administrator)
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references: <w4ka0es7pi.fsf@cln46ac.der.edfgdf.fr>
 <3152FC34.648B@nl.cis.philips.com>
organization: Raytheon Electronic Systems, Portsmouth RI Facility
newsgroups: comp.lang.ada
Date: 1996-04-01T00:00:00+00:00
List-Id: <comp.lang.ada>

I just tried do something like the following:

   type Record_Type(Has_Value : Boolean) is
       record
         case Has_Value is
            when True =>
	        Value : Integer;
            when False =>
                null;
         end case;

   Object : Record_Type := (Has_Value => True, Value => 1);

   Discriminant : Boolean renames Object.Has_Value; -- error
   Component : Integer renames Object.Value; -- error

(there may be a typo or something in there, this is off the top of my head)

The Intermetrics compiler I am using complains that:
Object.Has_Value depends on discriminants of an unconstrained formal 
parameter with default discriminants [RM_95 8.5.1(5)]

RM_95 8.5.1(5) reads:
   The renamed entity shall not be a subcomponent that depends on
   discriminants of a variable whose nominal subtype is unconstrained,
   unless this subtype is indefinite, or the variable is aliased. A
   slice of an array shall not be renamed if this restriction
   disallows renaming of the array. 

This says to me that the second renames I have is illegal.  I am not sure 
why the first renames is illegal.  Why can't I rename the discriminant?

Note that in the real code, the Object is an 'in' parameter.

I'm not sure if this is a language issue, a compiler problem, or just a 
lack of understanding on my part.  Could anyone help clarify?

Thanks...

--
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Chris Felaco                               Phone: x4631 (Raynet 444, Local 842)
Raytheon Company                                         Email: bcf@ssd.ray.com
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