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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: access check failure in "adjust" of a controlled type in
 aggregate assignement but not with normal variable assignement
Date: Thu, 17 May 2018 21:48:40 +0300
Organization: Tidorum Ltd
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Xref: reader02.eternal-september.org comp.lang.ada:52403
Date: 2018-05-17T21:48:40+03:00
List-Id: <comp.lang.ada>

On 18-05-17 20:21 , Mehdi Saada wrote:
> I used controlled type to implement deep copy of lists, but I get
> raised PROGRAM_ERROR : adjust/finalize raised CONSTRAINT_ERROR: essai2.adb:61 access check failed
>
> The definitions:
> type Matrice_Creuse is new Ada.Finalization.Controlled with record
> 	 First       : Node_Access;
> 	 Number      : Natural := 0;
> 	 Max_Indices : T_INDICE := (0, 0);
>       end record;
> type t_indice is record
>  	Column, Line : natural ;
> end record;
>  procedure Adjust (Matrice : in out Matrice_Creuse) is
>       begin
> 	 if Matrice.First = null then return;
> 	 else
> 	    declare
> 	       Iter   : Node_Access := Matrice.First;
> 	       Iter_R : Node_Access := new Node'(Iter.all);
> 	    begin
> 	       for I in 2 .. Matrice.Number loop
> 		  pragma Assert (Iter /= null); -- useless
> 		  Iter_R.Next := new Node'(Iter.Next.all);
> 		  Iter := Iter.Next; -- LINE 61 HEEEEREEE
> 		  Iter_R := Iter_R.Next;
> 	       end loop;
> 	    end;
> 	 end if;
>       end Adjust;

Your Adjust never reassigns Matrice.First, so it continues to refer to 
the original list, not to the new deep copy.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
       .      @       .