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-- C460002.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.

--     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making

--     this public release, the Government intends to confer upon all

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

--     These rights include rights to use, duplicate, release or disclose the

--     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

--     to do so.

--

--                                    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 if the target type of a type conversion is a general

--      access type, Program_Error is raised if the accessibility level

--      of the operand type is deeper than that of the target type.

--      Check for the case where the operand is an access parameter,

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

--      access parameter.

--

-- TEST DESCRIPTION:

--      In order to satisfy accessibility requirements, the operand type

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

--      type -- the operand type must "live" as long as the target type.

--      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

--      a type conversion is attempted on the access parameter to an access

--      type A 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 target type -- 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 := A(X);          -- 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, the type conversion 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

--      19 Dec 94   SAIC    Changed maintenance documentation.

--      15 Jul 98   EDS     Avoid Optimization

--      28 Jun 02   RLB     Added pragma Elaborate_All.

--!

with Report; use Report; pragma Elaborate_All (Report);

package C460002_0 is

   type Component is array (1 .. 10) of Natural;

   type Desig is record

      C: Component;

   end record;

   X0 : aliased Desig := (C=>(others => 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 C460002_0;

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

package body C460002_0 is

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

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

      -- This procedure attempts a type conversion on the access parameter to

      -- an access type 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.

      begin

         -- The accessibility level of type Acc_L0 is 0.

         A0 := Acc_L0(X);

         R  := OK;

      exception

         when Program_Error =>

            R := P_E;

         when others        =>

            R := O_E;

      end Nested;

   begin

      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

         -- The type conversion below will always be safe, since the

         -- accessibility level (although not necessarily the static nesting

         -- depth) of Acc_Deeper will always be deeper than or the same as that

         -- of the actual corresponding to Y.

         AD := Acc_Deeper(X);

         if Natural(Ident_Int(AD.C(1))) /= 3 then            --Avoid Optimization of AD

           Report.Failed ("Initial Values not correct.");

         end if;

         return OK;

      exception

         when Program_Error =>

            return P_E;

         when others        =>

            return O_E;

      end Nested;

   begin

      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;

   begin

      -- The type conversion below will always be safe, since the

      -- accessibility level (although not necessarily the static nesting

      -- depth) of Acc_Local will always be deeper than or the same as that

      -- of the actual corresponding to X.

      AL := Acc_Local(X);

      if Natural(Ident_Int(AL.C(1))) /= 3 then       --Avoid Optimization of AL

        Report.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 C460002_0;

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

with C460002_0;

use  C460002_0;

with Report; use Report;

procedure C460002 is

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

   A1 : Acc_L1;

   X1 : aliased Desig := (C=>(others => Ident_Int(3)));

   Res : Result_Kind;

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

   begin

      -- The accessibility level of type Acc_L1 is 1.

      A1 := Acc_L1(X);

      if Natural(Ident_Int(A1.C(1))) /= 3 then       --Avoid Optimization of A1

        Report.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 -- C460002.

   Report.Test ("C460002", "Check that if the target type of a type "      &

                "conversion is a general access type, Program_Error is "   &

                "raised if the accessibility level of the operand type "   &

                "is deeper than that of the target type: operand 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 := (C=>(others => 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 C460002;