-- C460002.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 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;