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-- C3A2003.A

--

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--     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,

--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained

--     unlimited rights in the software and documentation contained herein.

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--     recipients unlimited rights  equal to those held by the Government.

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--     released technical data and computer software in whole or in part, in

--     any manner and for any purpose whatsoever, and to have or permit others

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--

--                                    DISCLAIMER

--

--     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR

--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED

--     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE

--     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE

--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A

--     PARTICULAR PURPOSE OF SAID MATERIAL.

--*

--

-- OBJECTIVE:

--      Check that, for X'Access of a general access type A, Program_Error is

--      raised if the accessibility level of X is deeper than that of A.

--      Check for the case where X denotes a view that is a dereference of an

--      access parameter, or a rename thereof. Check for the case where X is

--      an access parameter and the corresponding actual is another access

--      parameter.

--

-- TEST DESCRIPTION:

--      In order to satisfy accessibility requirements, the designated

--      object X must be at the same or a less deep nesting level than the

--      general access type A -- X must "live" as long as A. Nesting

--      levels are the run-time nestings of masters: block statements;

--      subprogram, task, and entry bodies; and accept statements. Packages

--      are invisible to accessibility rules.

--

--      This test declares subprograms with access parameters, within which

--      'Access is attempted on a dereference of an access parameter, and

--      assigned to an access object whose type A is declared at some nesting

--      level. The test verifies that Program_Error is raised if the actual

--      corresponding to the access parameter is another access parameter,

--      and the actual corresponding to this second access parameter is:

--

--         (1) an expression of a named access type, and the accessibility

--             level of the named access type is deeper than that of the

--             access type A.

--

--         (2) a reference to the Access attribute (e.g., X'Access), and

--             the accessibility level of X is deeper than that of the

--             access type A.

--

--      Note that the static nesting level of the actual corresponding to the

--      access parameter can be deeper than that of the type A -- it is

--      the run-time nesting that matters for accessibility rules. Consider

--      the case where the access type A is declared within the called

--      subprogram. The accessibility check will never fail, even if the

--      actual happens to have a deeper static nesting level:

--

--         procedure P (X: access T) is

--            type A is access all T;   -- Static level = 2, e.g.

--            Acc : A := X.all'Access;  -- Check should never fail.

--         begin null; end;

--         . . .

--         procedure Q (Y: access T) is

--         begin

--            P(Y);

--         end;

--         . . .

--         declare

--            Actual : aliased T;       -- Static level = 3, e.g.

--         begin

--            Q (Actual'Access);

--         end;

--

--         For the execution of Q (and hence P), the accessibility level of

--         type A will always be deeper than that of Actual, so there is no

--         danger of a dangling reference arising from the assignment to

--         Acc. Thus, X.all'Access is safe, even though the static nesting

--         level of Actual is deeper than that of A.

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC   ACVC 2.0

--      15 Jul 98   EDS    Avoid optimization.

--      28 Jun 02   RLB    Added pragma Elaborate_All (Report);.

--!

with report; use report; pragma Elaborate_All (report);

package C3A2003_0 is

   type Desig is array (1 .. 10) of Integer;

   X0 : aliased Desig := (Desig'Range => Ident_Int(3));           -- Level = 0.

   type Acc_L0 is access all Desig;                               -- Level = 0.

   A0 : Acc_L0;

   type Result_Kind is (OK, P_E, O_E);

   procedure Target_Is_Level_0_Nest (Y: access Desig; S: out Result_Kind);

   procedure Never_Fails_Nest       (Y: access Desig; S: out Result_Kind);

   procedure Never_Fails_Same       (Y: access Desig; S: out Result_Kind);

end C3A2003_0;

     --==================================================================--

package body C3A2003_0 is

   procedure Target_Is_Level_0_Nest (Y: access Desig; S: out Result_Kind) is

      -- This procedure utilizes 'Access on a dereference of an access

      -- parameter, and assigned to an access object whose type A is

      -- declared at some nesting level.  Program_Error is raised if

      -- the accessibility level of the operand type is deeper than that

      -- of the target type.

      procedure Nested (X: access Desig; R: out Result_Kind) is

         -- Dereference of an access_to_object value is aliased.

         Ren : Desig renames X.all;                -- Renaming of a dereference

      begin                                        -- of an access parameter.

         -- The accessibility level of type A0 is 0.

         A0 := Ren'Access;

         R  := OK;

      exception

         when Program_Error =>

            R := P_E;

         when others        =>

            R := O_E;

      end Nested;

   begin   -- Target_Is_Level_0_Nest

      Nested (Y, S);

   end Target_Is_Level_0_Nest;

   ------------------------------------------------------------------

   procedure Never_Fails_Nest (Y: access Desig; S: out Result_Kind) is

      type Acc_Deeper is access all Desig;

      AD : Acc_Deeper;

      function Nested (X: access Desig) return Result_Kind is

      begin

         -- X.all'Access below will always be safe, since the accessibility

         -- level (although not necessarily the static nesting depth) of the

         -- type of AD will always be deeper than or the same as that of the

         -- actual corresponding to Y.

         AD := X.all'Access;

         if Ident_Int (AD(4)) /= 3 then            --Avoid Optimization of AD

           FAILED ("Initial Values not correct.");

         end if;

         return OK;

      exception

         when Program_Error =>

            return P_E;

         when others        =>

            return O_E;

      end Nested;

   begin  -- Never_Fails_Nest

      S := Nested (Y);

   end Never_Fails_Nest;

   ------------------------------------------------------------------

   procedure Called_By_Never_Fails_Same

     (X: access Desig; R: out Result_Kind) is

      type Acc_Local is access all Desig;

      AL : Acc_Local;

      -- Dereference of an access_to_object value is aliased.

      Ren : Desig renames X.all;                   -- Renaming of a dereference

   begin                                           -- of an access parameter.

      -- Ren'Access below will always be safe, since the accessibility

      -- level (although not necessarily the static nesting depth) of

      -- type of AL will always be deeper than or the same as that of the

      -- actual corresponding to Y.

      AL := Ren'Access;

      if Ident_Int (AL(4)) /= 3 then       --Avoid Optimization of AL

        FAILED ("Initial Values not correct.");

      end if;

      R  := OK;

   exception

      when Program_Error =>

         R := P_E;

      when others        =>

         R := O_E;

   end Called_By_Never_Fails_Same;

   ------------------------------------------------------------------

   procedure Never_Fails_Same (Y: access Desig; S: out Result_Kind) is

   begin

      Called_By_Never_Fails_Same (Y, S);

   end Never_Fails_Same;

end C3A2003_0;

     --==================================================================--

with C3A2003_0;

use  C3A2003_0;

with Report; use report;

procedure C3A2003 is

   type Acc_L1 is access all Desig;                               -- Level = 1.

   A1  : Acc_L1;

   X1 : aliased Desig := (Desig'Range => Ident_Int(3));

   Res : Result_Kind;

   procedure Called_By_Target_L1 (X: access Desig; R: out Result_Kind) is

   begin

      -- The accessibility level of the type of A1 is 1.

      A1 := X.all'Access;

      if IDENT_INT (A1(4)) /= 3 then       --Avoid optimization of A1

        FAILED ("Initial values not correct.");

      end if;

      R  := OK;

   exception

      when Program_Error =>

         R := P_E;

      when others        =>

         R := O_E;

   end Called_By_Target_L1;

   ------------------------------------------------------------------

   function Target_Is_Level_1_Same (Y: access Desig) return Result_Kind is

      S : Result_Kind;

   begin

      Called_By_Target_L1 (Y, S);

      return S;

   end Target_Is_Level_1_Same;

   ------------------------------------------------------------------

   procedure Display_Results (Result  : in Result_Kind;

                              Expected: in Result_Kind;

                              Msg     : in String) is

   begin

      if Result /= Expected then

         case Result is

            when OK  => Report.Failed ("No exception raised: "         & Msg);

            when P_E => Report.Failed ("Program_Error raised: "        & Msg);

            when O_E => Report.Failed ("Unexpected exception raised: " & Msg);

         end case;

      end if;

   end Display_Results;

begin -- C3A2003

   Report.Test ("C3A2003", "Check that, for X'Access of general access "   &

                "type A, Program_Error is raised if the accessibility "    &

                "level of X is deeper than that of A: X is an access "     &

                "parameter; corresponding actual is another access "       &

                "parameter");

   -- Accessibility level of actual is 0 (actual is X'Access):

   Never_Fails_Same (X0'Access, Res);

   Display_Results (Res, OK, "Never_Fails_Same, level 0 actual");

   Never_Fails_Nest (X0'Access, Res);

   Display_Results (Res, OK, "Target_L1_Nest, level 0 actual");

   Target_Is_Level_0_Nest (X0'Access, Res);

   Display_Results (Res, OK, "Target_L0_Nest, level 0 actual");

   Res := Target_Is_Level_1_Same (X0'Access);

   Display_Results (Res, OK, "Target_L1_Same, level 0 actual");

   -- Accessibility level of actual is 1 (actual is X'Access):

   Never_Fails_Same (X1'Access, Res);

   Display_Results (Res, OK, "Never_Fails_Same, level 1 actual");

   Never_Fails_Nest (X1'Access, Res);

   Display_Results (Res, OK, "Target_L1_Nest, level 1 actual");

   Target_Is_Level_0_Nest (X1'Access, Res);

   Display_Results (Res, P_E, "Target_L0_Nest, level 1 actual");

   Res := Target_Is_Level_1_Same (X1'Access);

   Display_Results (Res, OK, "Target_L1_Same, level 1 actual");

   Block_L2:

   declare

      X2 : aliased Desig := (Desig'Range => Ident_Int(3));

      type Acc_L2 is access all Desig;                            -- Level = 2.

      Expr_L2 : Acc_L2 := X2'Access;

   begin

      -- Accessibility level of actual is 2 (actual is expression of named

      -- access type):

      Never_Fails_Same (Expr_L2, Res);

      Display_Results (Res, OK, "Never_Fails_Same, level 2 actual");

      Never_Fails_Nest (Expr_L2, Res);

      Display_Results (Res, OK, "Target_L1_Nest, level 2 actual");

      Target_Is_Level_0_Nest (Expr_L2, Res);

      Display_Results (Res, P_E, "Target_L0_Nest, level 2 actual");

      Res := Target_Is_Level_1_Same (Expr_L2);

      Display_Results (Res, P_E, "Target_L1_Same, level 2 actual");

   end Block_L2;

   Report.Result;

end C3A2003;