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-- C460001.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.

--

--      Check for cases where the actual corresponding to the access

--      parameter is:

--         (a) An allocator.

--         (b) An expression of a named access type.

--         (c) Obj'Access.

--

-- 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:

--

--         (1) an allocator, and the accessibility level of the execution

--             of the called subprogram is deeper than that of the access

--             type A.

--

--         (2) 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.

--

--         (3) 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;

--         . . .

--         declare

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

--         begin

--            P (Actual'Access);

--         end;

--

--         For the execution of 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

--

--!

package C460001_0 is

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

   X0 : aliased Desig;                                            -- 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 (X: access Desig; R : out Result_Kind);

   procedure Never_Fails       (X: access Desig; R : out Result_Kind);

end C460001_0;

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

package body C460001_0 is

   procedure Target_Is_Level_0 (X : access Desig;

                                R : out Result_Kind) is

   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 Target_Is_Level_0;

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

   procedure Never_Fails (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);

      R  := OK;

   exception

      when Program_Error =>

         R := P_E;

      when others        =>

         R := O_E;

   end Never_Fails;

end C460001_0;

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

with C460001_0;

with Report;

procedure C460001 is

   X1 : aliased C460001_0.Desig;                                  -- Level = 1.

   type Acc_L1 is access all C460001_0.Desig;                     -- Level = 1.

   A1 : Acc_L1;

   Expr_L0 : C460001_0.Acc_L0 := C460001_0.X0'Access;

   Expr_L1 : Acc_L1           := X1'Access;

   Res : C460001_0.Result_Kind;

   use type C460001_0.Result_Kind;

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

   procedure Target_Is_Level_1 (X : access C460001_0.Desig;

                                R : out C460001_0.Result_Kind) is

   begin

      -- The accessibility level of type Acc_L1 is 1.

      A1 := Acc_L1(X);

      R  := C460001_0.OK;

   exception

      when Program_Error =>

         R := C460001_0.P_E;

      when others        =>

         R := C460001_0.O_E;

   end Target_Is_Level_1;

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

   procedure Display_Results (Result  : in C460001_0.Result_Kind;

                              Expected: in C460001_0.Result_Kind;

                              Message : in String) is

   begin

      if Result /= Expected then

         case Result is

            when C460001_0.OK  => Report.Failed ("No exception raised: "  &

                                                 Message);

            when C460001_0.P_E => Report.Failed ("Program_Error raised: " &

                                                 Message);

            when C460001_0.O_E => Report.Failed ("Unexpected exception "  &

                                                 "raised: " & Message);

         end case;

      end if;

   end Display_Results;

begin -- C460001

   Report.Test ("C460001", "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 an allocator, " &

                "expression of a named access type, Obj'Access");

   -- Actual is X'Access:

   C460001_0.Never_Fails (X1'Access, Res);

   Display_Results (Res, C460001_0.OK, "X1'Access, local access type");

   C460001_0.Target_Is_Level_0 (X1'Access, Res);

   Display_Results (Res, C460001_0.P_E, "X1'Access, level 0 access type");

   Target_Is_Level_1 (C460001_0.X0'Access, Res);

   Display_Results (Res, C460001_0.OK, "X0'Access, level 1 access type");

   Target_Is_Level_1 (X1'Access, Res);

   Display_Results (Res, C460001_0.OK, "X1'Access, level 1 access type");

   C460001_0.Target_Is_Level_0 (C460001_0.X0'Access, Res);

   Display_Results (Res, C460001_0.OK, "X0'Access, level 0 access type");

   -- Actual is expression of a named access type:

   C460001_0.Never_Fails (Expr_L0, Res);

   Display_Results (Res, C460001_0.OK, "Expr_L0, local access type");

   C460001_0.Target_Is_Level_0 (Expr_L0, Res);

   Display_Results (Res, C460001_0.OK, "Expr_L0, level 0 access type");

   C460001_0.Target_Is_Level_0 (Expr_L1, Res);

   Display_Results (Res, C460001_0.P_E, "Expr_L1, level 0 access type");

   Target_Is_Level_1 (Expr_L1, Res);

   Display_Results (Res, C460001_0.OK, "Expr_L1, level 1 access type");

   Target_Is_Level_1 (Expr_L0, Res);

   Display_Results (Res, C460001_0.OK, "Expr_L0, level 1 access type");

   -- Actual is allocator (level of execution = 2):

   C460001_0.Never_Fails (new C460001_0.Desig, Res);

   Display_Results (Res, C460001_0.OK, "Allocator level 2, " &

                                       "local access type");

   C460001_0.Target_Is_Level_0 (new C460001_0.Desig, Res);

   Display_Results (Res, C460001_0.P_E, "Allocator level 2, " &

                                        "level 0 access type");

   Target_Is_Level_1 (new C460001_0.Desig, Res);

   Display_Results (Res, C460001_0.P_E, "Allocator level 2, " &

                                        "level 1 access type");

   Block_L2:

   declare

      X2 : aliased C460001_0.Desig;                               -- Level = 2.

      type Acc_L2 is access all C460001_0.Desig;                  -- Level = 2.

      Expr_L2 : Acc_L2 := X1'Access;

   begin

      -- Actual is X'Access:

      C460001_0.Never_Fails (X2'Access, Res);

      Display_Results (Res, C460001_0.OK, "X2'Access, local access type");

      Target_Is_Level_1 (X2'Access, Res);

      Display_Results (Res, C460001_0.P_E, "X2'Access, level 1 access type");

      -- Actual is expression of a named access type:

      C460001_0.Never_Fails (Expr_L2, Res);

      Display_Results (Res, C460001_0.OK, "Expr_L2, local access type");

      C460001_0.Target_Is_Level_0 (Expr_L2, Res);

      Display_Results (Res, C460001_0.P_E, "Expr_L2, level 0 access type");

      -- Actual is allocator (level of execution = 3):

      C460001_0.Never_Fails (new C460001_0.Desig, Res);

      Display_Results (Res, C460001_0.OK, "Allocator level 3, " &

                                          "local access type");

      Target_Is_Level_1 (new C460001_0.Desig, Res);

      Display_Results (Res, C460001_0.P_E, "Allocator level 3, " &

                                           "level 1 access type");

   end Block_L2;

   Report.Result;

end C460001;