Re: unexpected behaviour of finalize

[stefan-lucks@see-the.signature]

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> This looks like a pretty clear compiler bug, especially since by the
> time Finalize is called by the outermost Do_Something, it's using, for
> the value of I, the parameter from a Do_Something call that is no
> longer active.  It shouldn't be hard to modify this slightly, using
> (say) a string or record as a parameter to Do_Something, to create a
> test where utter garbage is displayed; then it would be clearer that
> this is a compiler bug.

Good idea! Yes, the following change makes the program output a bit of 
garbage, as you guessed:

procedure Strong_Fin_Test_Case is

   type Fin is new Ada.Finalization.Limited_Controlled with null record;

   procedure Do_Something (I: Natural) is

      A: String(1 .. 5); -- this is new

      type My_Fin is new Fin with null record;
      overriding procedure Finalize(Self: in out My_Fin) is
      begin
         Ada.Text_IO.Put_Line("  Do_Something Finalization " & A);
      end Finalize;
      Singleton: My_Fin;

   begin -- Do_Something
      Ada.Text_IO.Put_Line("  I = " & Natural'Image(I));
      if I>0 then
         Do_Something(I-1);
         Do_Something(I-1);
      end if;
      A(1 .. 5) := ("ABCDE"); -- always the same
   end Do_Something;

begin
   Ada.Text_IO.Put_Line("Start Do_Something (2)");
   Do_Something(2);
   Ada.Text_IO.Put_Line("Stop Do_Something (2)");
end Strong_Fin_Test_Case;


The putput:


Start Do_Something (2)
  I =  2
  I =  1
  I =  0
  Do_Something Finalization ABCDE
  I =  0
  Do_Something Finalization ABCDE
  Do_Something Finalization ABCDE
  I =  1
  I =  0
  Do_Something Finalization ABCDE
  I =  0
  Do_Something Finalization ABCDE
  Do_Something Finalization ABCDE
  Do_Something Finalization �l
Stop Do_Something (2)

The last line before "Stop Do_Something (2)" contains some strange 
characters instead of the constant "ABCDE" it should output. Furthermore, 
this output is not always the same. 

So long

Stefan



-- 
------ Stefan Lucks   --  Bauhaus-University Weimar  --   Germany  ------
               Stefan dot Lucks at uni minus weimar dot de
------  I  love  the  taste  of  Cryptanalysis  in  the  morning!  ------