Re: Bug in Ada (SuSe 10.2) ?

[billjones6789@yahoo.com]

On Feb 22, 11:52 am, "Randy Brukardt" <ra...@rrsoftware.com> wrote:
> These aren't "dangling pointer" checks (which would occur on the
> dereference). If you wanted to talk about them informally, I'd call them
> "lifetime" checks, but it is best to call them by their real name (which you
> finally did above). I thought you were talking about something completely
> different.

Sorry to confuse you.  Maybe my English is not so good.
I was referring to this language-defined check by its high-level
purpose
rather than its low-level implementation model, the same way it is
introduced in RM 3.10.2 paragraph 1, "The accessibility rules prevent
dangling references ...".

> Anyway, accessibility checks contain both a static and dynamic part, and it
> is fairly difficult to write an interesting program that passes the static
> check and fails the dynamic check.

I provided what I thought to be a rather simple example program that
demonstrated the dynamic case.  Do you mean to say that this example
is
fairly difficult to use in an interesting program?  It did include
an
access discriminant, which may be confusing, but that can be easily
removed, as follows:

with Ada.Text_IO;
procedure Dangling_Pointer2 is
   type Int_Access is access all integer;

   Save : Int_Access;

   type AirSpeed is record
      Altitude : aliased integer := 9;
   end record;

   function WoW (Slats: access AirSpeed) return Int_Access is
   begin
      return Slats.Altitude'Access;
   end WoW;

   procedure Calculate is
      Heading : aliased AirSpeed;
   begin
      Save := WoW (Heading'access);
      Ada.Text_IO.Put_Line (integer'image(Save.all));
   end Calculate;

   procedure Mess_with_stack is
      Dummy: array(1..10) of integer := (others => 17);
   begin
      null;
   end Mess_with_stack;

begin
   Calculate;
   Mess_with_stack;
   Ada.Text_IO.Put_Line (integer'image(Save.all));
end Dangling_Pointer2;