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From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Possible GNAT bug,
 but wanted to see if it was a violtion of the RM
Date: Sun, 25 Feb 2018 11:55:11 +0000
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Date: 2018-02-25T11:55:11+00:00
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Jere <jhb.chat@gmail.com> writes:

> Thanks!  That confirms my initial suspicion of it being related to
> tamper checks, but I can't figure out how.  I looked through the GNAT
> code and saw how they locked it in the Constant_Reference function,
> but I can't for the life of me figure out how calling it using:
>
>    Package.Operation(Object,Params).Discriminant
>
> would work differently than
>
>    Object.Operation(Params).Discriminant 
>
> for that function call.

Compiling with -gnatG (to list an Ada-like representation of what the
compiler has transformed your code into before it starts
optimisation/code generation) shows that the Package.Operation version
includes some finalization in Operation that's missing in the
Object.Operation version. Looks very like a bug!