using package GNAT.Traceback

["Christophe Gouiran" <christophe@e-motive.com>]

Hi everyone, do you know how to use package GNAT.Traceback ?

In my source i write :

procedure IExplore is
   dummy : natural;
begin

   dummy := -1; -- will raise constraint_error

   exception when e: others =>
      declare
         tarray : Tracebacks_Array(1 .. 100);
         len : integer;
      begin
         Call_Chain(tarray, len);

         put_line("Callback number : " & integer'image(len));


      end;

end IExplore;


But i have the output :
Callback number :  0

I have gnat 3.12p under Win 2000 .
If someone knows the answer ...