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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: Re: Deallocating an object twice
References: <lr1142$log$1@speranza.aioe.org> <85bnsarfad.fsf@stephe-leake.org>
 	<lr3658$e1g$1@speranza.aioe.org>
Date: Mon, 28 Jul 2014 10:15:27 -0500
Message-ID: <8538dlqzu8.fsf@stephe-leake.org>
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Date: 2014-07-28T10:15:27-05:00
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Victor Porton <porton@narod.ru> writes:

> Stephen Leake wrote:
>
>> Victor Porton <porton@narod.ru> writes:
>> 
>>> If I understand correctly, it is an undefined behavior (or is it called
>>> unbounded error?) if a pool access is deallocated twice with
>>> Unchecked_Deallocation.
>> 
>> You misunderstand.
>> 
>> ARM 2012 13.11.3
>> 
>> Procedure Free has the following effect:
>> 
>> 7
>>      1.  After executing Free(X), the value of X is null.
>> 
>> 8
>>      2.  Free(X), when X is already equal to null, has no effect.
>
> No, it is that you misunderstand me:
>
> Second free may be executed not as Free(X) but as Free(Y) where Y was a copy 
> of X (and so Free(X) sets only X to null, it does not set Y to null; and 
> Free(Y) would be erroneous).

Ok, that makes sense. 

Don't copy pointers! It is the copy of the pointer that is bad, not the
behavior of Unchecked_Deallocation.

-- 
-- Stephe