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-- C3A2002.A
--
-- Grant of Unlimited Rights
--
-- 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, 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 cases where the actual corresponding to X is:
-- (a) An allocator.
-- (b) An expression of a named access type.
-- (c) Obj'Access.
--
-- 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 the 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:
--
-- (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 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;
-- . . .
-- 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,
-- 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
--
--!
package C3A2002_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 A_Is_Level_0 (X: access Desig; R : out Result_Kind);
procedure Never_Fails (X: access Desig; R : out Result_Kind);
end C3A2002_0;
--==================================================================--
package body C3A2002_0 is
procedure A_Is_Level_0 (X : access Desig;
R : out Result_Kind) is
begin
-- The accessibility level of the type of A0 is 0.
A0 := X.all'Access;
R := OK;
exception
when Program_Error =>
R := P_E;
when others =>
R := O_E;
end A_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
-- X.all'Access below will always be safe, since the accessibility
-- level (although not necessarily the static nesting depth) of the
-- type of AL will always be deeper than or the same as that of the
-- actual corresponding to Y.
AL := X.all'Access;
R := OK;
exception
when Program_Error =>
R := P_E;
when others =>
R := O_E;
end Never_Fails;
end C3A2002_0;
--==================================================================--
with C3A2002_0;
with Report;
procedure C3A2002 is
X1 : aliased C3A2002_0.Desig; -- Level = 1.
type Acc_L1 is access all C3A2002_0.Desig; -- Level = 1.
A1 : Acc_L1;
Expr_L0 : C3A2002_0.Acc_L0 := C3A2002_0.X0'Access;
Expr_L1 : Acc_L1 := X1'Access;
Res : C3A2002_0.Result_Kind;
use type C3A2002_0.Result_Kind;
-----------------------------------------------
procedure A_Is_Level_1 (X : access C3A2002_0.Desig;
R : out C3A2002_0.Result_Kind) is
-- Dereference of an access_to_object value is aliased.
Ren : C3A2002_0.Desig renames X.all; -- Renaming of a dereference
begin -- of an access parameter.
-- The accessibility level of the type of A1 is 1.
A1 := Ren'Access;
R := C3A2002_0.OK;
exception
when Program_Error =>
R := C3A2002_0.P_E;
when others =>
R := C3A2002_0.O_E;
end A_Is_Level_1;
-----------------------------------------------
procedure Display_Results (Result : in C3A2002_0.Result_Kind;
Expected: in C3A2002_0.Result_Kind;
Message : in String) is
begin
if Result /= Expected then
case Result is
when C3A2002_0.OK => Report.Failed ("No exception raised: " &
Message);
when C3A2002_0.P_E => Report.Failed ("Program_Error raised: " &
Message);
when C3A2002_0.O_E => Report.Failed ("Unexpected exception " &
"raised: " & Message);
end case;
end if;
end Display_Results;
begin -- C3A2002
Report.Test ("C3A2002", "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 an allocator, " &
"expression of a named access type, Obj'Access, or a " &
"rename thereof");
-- Actual is X'Access:
C3A2002_0.Never_Fails (C3A2002_0.X0'Access, Res);
Display_Results (Res, C3A2002_0.OK, "X0'Access, local access type");
C3A2002_0.A_Is_Level_0 (C3A2002_0.X0'Access, Res);
Display_Results (Res, C3A2002_0.OK, "X0'Access, level 0 access type");
C3A2002_0.A_Is_Level_0 (X1'Access, Res);
Display_Results (Res, C3A2002_0.P_E, "X1'Access, level 0 access type");
A_Is_Level_1 (X1'Access, Res);
Display_Results (Res, C3A2002_0.OK, "X1'Access, level 1 access type");
-- Actual is expression of a named access type:
C3A2002_0.Never_Fails (Expr_L1, Res);
Display_Results (Res, C3A2002_0.OK, "Expr_L1, local access type");
C3A2002_0.A_Is_Level_0 (Expr_L1, Res);
Display_Results (Res, C3A2002_0.P_E, "Expr_L1, level 0 access type");
A_Is_Level_1 (Expr_L0, Res);
Display_Results (Res, C3A2002_0.OK, "Expr_L0, level 1 access type");
A_Is_Level_1 (Expr_L1, Res);
Display_Results (Res, C3A2002_0.OK, "Expr_L1, level 1 access type");
-- Actual is allocator (level of execution = 2):
C3A2002_0.Never_Fails (new C3A2002_0.Desig, Res);
Display_Results (Res, C3A2002_0.OK, "Allocator level 2, " &
"local access type");
-- Since actual is an allocator, its accessibility level is that of
-- the execution of the called subprogram, i.e., level 2.
C3A2002_0.A_Is_Level_0 (new C3A2002_0.Desig, Res);
Display_Results (Res, C3A2002_0.P_E, "Allocator level 2, " &
"level 0 access type");
A_Is_Level_1 (new C3A2002_0.Desig, Res);
Display_Results (Res, C3A2002_0.P_E, "Allocator level 2, " &
"level 1 access type");
Block_L2:
declare
X2 : aliased C3A2002_0.Desig; -- Level = 2.
type Acc_L2 is access all C3A2002_0.Desig; -- Level = 2.
Expr_L2 : Acc_L2 := X1'Access;
begin
-- Actual is X'Access:
C3A2002_0.Never_Fails (X2'Access, Res);
Display_Results (Res, C3A2002_0.OK, "X2'Access, local access type");
C3A2002_0.A_Is_Level_0 (X2'Access, Res);
Display_Results (Res, C3A2002_0.P_E, "X2'Access, level 0 access type");
-- Actual is expression of a named access type:
A_Is_Level_1 (Expr_L2, Res);
Display_Results (Res, C3A2002_0.P_E, "Expr_L2, level 1 access type");
-- Actual is allocator (level of execution = 3):
C3A2002_0.Never_Fails (new C3A2002_0.Desig, Res);
Display_Results (Res, C3A2002_0.OK, "Allocator level 3, " &
"local access type");
A_Is_Level_1 (new C3A2002_0.Desig, Res);
Display_Results (Res, C3A2002_0.P_E, "Allocator level 3, " &
"level 1 access type");
end Block_L2;
Report.Result;
end C3A2002;
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