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From: Maciej Sobczak <see.my.homepage@gmail.com>
Newsgroups: comp.lang.ada
Subject: How many Ada compiler bugs are here?
Date: Thu, 12 Jan 2012 15:20:22 -0800 (PST)
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Date: 2012-01-12T15:20:22-08:00
List-Id: <comp.lang.ada>

Consider:

with Ada.Finalization;
with Ada.Text_IO;

procedure Test is

   package P is
      Some_Error : exception;
      type T (<>) is limited private;
      function Make_T return T;
   private
      type T is new Ada.Finalization.Limited_Controlled with
         record
            Initialized : Boolean := False;
         end record;

      overriding procedure Adjust (V : in out T);
      overriding procedure Finalize (V : in out T);
   end P;

   package body P is
      function Make_T return T is
      begin
         raise Some_Error;

         --  needed to please the compiler:
         return (Ada.Finalization.Limited_Controlled
                   with others => <>);
      end Make_T;

      procedure Adjust (V : in out T) is
      begin
         Ada.Text_IO.Put_Line ("adjusting");
      end Adjust;

      procedure Finalize (V : in out T) is
      begin
         Ada.Text_IO.Put_Line
           ("finalizing with Initialized =" &
              Boolean'Image (V.Initialized));
      end Finalize;
   end P;

begin
   declare
      Tmp : P.T := P.Make_T;
   begin
      null;
   end;
exception
   when others =>
      Ada.Text_IO.Put_Line ("exception handled");
end Test;

This program prints (GNAT 2011):

$ ./test
finalizing with Initialized =TRUE
exception handled
$

Above:

1. Adjust should not be allowed to be declared (it is a *limited*
type). But I have defined it to trace the remaining bugs:
2. The return statement in Make_T should not be required, because it
is unreachable anyway.
3. Logically, Tmp is never created, because Make_T raises an
exception. Somehow some object is finalized. Apparently it is Tmp,
which should not exist.
4. Somehow Tmp.initialized = True, even though its default value is
defined to be False.

Guess how I found that out. It's past midnight here...

Are there any known workarounds?

--
Maciej Sobczak * http://www.msobczak.com * http://www.inspirel.com