1-- C460001.A 2-- 3-- Grant of Unlimited Rights 4-- 5-- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687, 6-- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 7-- unlimited rights in the software and documentation contained herein. 8-- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making 9-- this public release, the Government intends to confer upon all 10-- recipients unlimited rights equal to those held by the Government. 11-- These rights include rights to use, duplicate, release or disclose the 12-- released technical data and computer software in whole or in part, in 13-- any manner and for any purpose whatsoever, and to have or permit others 14-- to do so. 15-- 16-- DISCLAIMER 17-- 18-- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR 19-- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED 20-- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE 21-- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE 22-- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A 23-- PARTICULAR PURPOSE OF SAID MATERIAL. 24--* 25-- 26-- OBJECTIVE: 27-- Check that if the target type of a type conversion is a general 28-- access type, Program_Error is raised if the accessibility level 29-- of the operand type is deeper than that of the target type. 30-- Check for the case where the operand is an access parameter. 31-- 32-- Check for cases where the actual corresponding to the access 33-- parameter is: 34-- (a) An allocator. 35-- (b) An expression of a named access type. 36-- (c) Obj'Access. 37-- 38-- TEST DESCRIPTION: 39-- In order to satisfy accessibility requirements, the operand type 40-- must be at the same or a less deep nesting level than the target 41-- type -- the operand type must "live" as long as the target type. 42-- Nesting levels are the run-time nestings of masters: block statements; 43-- subprogram, task, and entry bodies; and accept statements. Packages 44-- are invisible to accessibility rules. 45-- 46-- This test declares subprograms with access parameters, within which 47-- a type conversion is attempted on the access parameter to an access 48-- type A declared at some nesting level. The test verifies that 49-- Program_Error is raised if the actual corresponding to the access 50-- parameter is: 51-- 52-- (1) an allocator, and the accessibility level of the execution 53-- of the called subprogram is deeper than that of the access 54-- type A. 55-- 56-- (2) an expression of a named access type, and the accessibility 57-- level of the named access type is deeper than that of the 58-- access type A. 59-- 60-- (3) a reference to the Access attribute (e.g., X'Access), and 61-- the accessibility level of X is deeper than that of the 62-- access type A. 63-- 64-- Note that the static nesting level of the actual corresponding to the 65-- access parameter can be deeper than that of the target type -- it is 66-- the run-time nesting that matters for accessibility rules. Consider 67-- the case where the access type A is declared within the called 68-- subprogram. The accessibility check will never fail, even if the 69-- actual happens to have a deeper static nesting level: 70-- 71-- procedure P (X: access T) is 72-- type A is access all T; -- Static level = 2, e.g. 73-- Acc : A := A(X); -- Check should never fail. 74-- begin null; end; 75-- . . . 76-- declare 77-- Actual : aliased T; -- Static level = 3, e.g. 78-- begin 79-- P (Actual'Access); 80-- end; 81-- 82-- For the execution of P, the accessibility level of type A will 83-- always be deeper than that of Actual, so there is no danger of a 84-- dangling reference arising from the assignment to Acc. Thus, the 85-- type conversion is safe, even though the static nesting level of 86-- Actual is deeper than that of A. 87-- 88-- 89-- CHANGE HISTORY: 90-- 06 Dec 94 SAIC ACVC 2.0 91-- 92--! 93 94package C460001_0 is 95 96 type Desig is array (1 .. 10) of Integer; 97 98 X0 : aliased Desig; -- Level = 0. 99 100 type Acc_L0 is access all Desig; -- Level = 0. 101 A0 : Acc_L0; 102 103 type Result_Kind is (OK, P_E, O_E); 104 105 procedure Target_Is_Level_0 (X: access Desig; R : out Result_Kind); 106 procedure Never_Fails (X: access Desig; R : out Result_Kind); 107 108end C460001_0; 109 110 111 --==================================================================-- 112 113 114package body C460001_0 is 115 116 procedure Target_Is_Level_0 (X : access Desig; 117 R : out Result_Kind) is 118 begin 119 -- The accessibility level of type Acc_L0 is 0. 120 A0 := Acc_L0(X); 121 R := OK; 122 exception 123 when Program_Error => 124 R := P_E; 125 when others => 126 R := O_E; 127 end Target_Is_Level_0; 128 129 ----------------------------------------------- 130 procedure Never_Fails (X: access Desig; 131 R : out Result_Kind) is 132 type Acc_Local is access all Desig; 133 AL : Acc_Local; 134 begin 135 -- The type conversion below will always be safe, since the 136 -- accessibility level (although not necessarily the static nesting 137 -- depth) of Acc_Local will always be deeper than or the same as that 138 -- of the actual corresponding to X. 139 AL := Acc_Local(X); 140 R := OK; 141 exception 142 when Program_Error => 143 R := P_E; 144 when others => 145 R := O_E; 146 end Never_Fails; 147 148end C460001_0; 149 150 151 --==================================================================-- 152 153 154with C460001_0; 155with Report; 156 157procedure C460001 is 158 159 X1 : aliased C460001_0.Desig; -- Level = 1. 160 161 type Acc_L1 is access all C460001_0.Desig; -- Level = 1. 162 A1 : Acc_L1; 163 164 Expr_L0 : C460001_0.Acc_L0 := C460001_0.X0'Access; 165 Expr_L1 : Acc_L1 := X1'Access; 166 167 Res : C460001_0.Result_Kind; 168 169 use type C460001_0.Result_Kind; 170 171 ----------------------------------------------- 172 procedure Target_Is_Level_1 (X : access C460001_0.Desig; 173 R : out C460001_0.Result_Kind) is 174 begin 175 -- The accessibility level of type Acc_L1 is 1. 176 A1 := Acc_L1(X); 177 R := C460001_0.OK; 178 exception 179 when Program_Error => 180 R := C460001_0.P_E; 181 when others => 182 R := C460001_0.O_E; 183 end Target_Is_Level_1; 184 185 ----------------------------------------------- 186 procedure Display_Results (Result : in C460001_0.Result_Kind; 187 Expected: in C460001_0.Result_Kind; 188 Message : in String) is 189 begin 190 if Result /= Expected then 191 case Result is 192 when C460001_0.OK => Report.Failed ("No exception raised: " & 193 Message); 194 when C460001_0.P_E => Report.Failed ("Program_Error raised: " & 195 Message); 196 when C460001_0.O_E => Report.Failed ("Unexpected exception " & 197 "raised: " & Message); 198 end case; 199 end if; 200 end Display_Results; 201 202begin -- C460001 203 204 Report.Test ("C460001", "Check that if the target type of a type " & 205 "conversion is a general access type, Program_Error is " & 206 "raised if the accessibility level of the operand type " & 207 "is deeper than that of the target type: operand is an " & 208 "access parameter; corresponding actual is an allocator, " & 209 "expression of a named access type, Obj'Access"); 210 211 212 -- Actual is X'Access: 213 214 C460001_0.Never_Fails (X1'Access, Res); 215 Display_Results (Res, C460001_0.OK, "X1'Access, local access type"); 216 217 C460001_0.Target_Is_Level_0 (X1'Access, Res); 218 Display_Results (Res, C460001_0.P_E, "X1'Access, level 0 access type"); 219 220 Target_Is_Level_1 (C460001_0.X0'Access, Res); 221 Display_Results (Res, C460001_0.OK, "X0'Access, level 1 access type"); 222 223 Target_Is_Level_1 (X1'Access, Res); 224 Display_Results (Res, C460001_0.OK, "X1'Access, level 1 access type"); 225 226 C460001_0.Target_Is_Level_0 (C460001_0.X0'Access, Res); 227 Display_Results (Res, C460001_0.OK, "X0'Access, level 0 access type"); 228 229 230 -- Actual is expression of a named access type: 231 232 C460001_0.Never_Fails (Expr_L0, Res); 233 Display_Results (Res, C460001_0.OK, "Expr_L0, local access type"); 234 235 C460001_0.Target_Is_Level_0 (Expr_L0, Res); 236 Display_Results (Res, C460001_0.OK, "Expr_L0, level 0 access type"); 237 238 C460001_0.Target_Is_Level_0 (Expr_L1, Res); 239 Display_Results (Res, C460001_0.P_E, "Expr_L1, level 0 access type"); 240 241 Target_Is_Level_1 (Expr_L1, Res); 242 Display_Results (Res, C460001_0.OK, "Expr_L1, level 1 access type"); 243 244 Target_Is_Level_1 (Expr_L0, Res); 245 Display_Results (Res, C460001_0.OK, "Expr_L0, level 1 access type"); 246 247 -- Actual is allocator (level of execution = 2): 248 249 C460001_0.Never_Fails (new C460001_0.Desig, Res); 250 Display_Results (Res, C460001_0.OK, "Allocator level 2, " & 251 "local access type"); 252 253 C460001_0.Target_Is_Level_0 (new C460001_0.Desig, Res); 254 Display_Results (Res, C460001_0.P_E, "Allocator level 2, " & 255 "level 0 access type"); 256 257 Target_Is_Level_1 (new C460001_0.Desig, Res); 258 Display_Results (Res, C460001_0.P_E, "Allocator level 2, " & 259 "level 1 access type"); 260 261 262 Block_L2: 263 declare 264 X2 : aliased C460001_0.Desig; -- Level = 2. 265 type Acc_L2 is access all C460001_0.Desig; -- Level = 2. 266 Expr_L2 : Acc_L2 := X1'Access; 267 begin 268 269 -- Actual is X'Access: 270 271 C460001_0.Never_Fails (X2'Access, Res); 272 Display_Results (Res, C460001_0.OK, "X2'Access, local access type"); 273 274 Target_Is_Level_1 (X2'Access, Res); 275 Display_Results (Res, C460001_0.P_E, "X2'Access, level 1 access type"); 276 277 -- Actual is expression of a named access type: 278 279 C460001_0.Never_Fails (Expr_L2, Res); 280 Display_Results (Res, C460001_0.OK, "Expr_L2, local access type"); 281 282 C460001_0.Target_Is_Level_0 (Expr_L2, Res); 283 Display_Results (Res, C460001_0.P_E, "Expr_L2, level 0 access type"); 284 285 286 -- Actual is allocator (level of execution = 3): 287 288 C460001_0.Never_Fails (new C460001_0.Desig, Res); 289 Display_Results (Res, C460001_0.OK, "Allocator level 3, " & 290 "local access type"); 291 292 Target_Is_Level_1 (new C460001_0.Desig, Res); 293 Display_Results (Res, C460001_0.P_E, "Allocator level 3, " & 294 "level 1 access type"); 295 296 end Block_L2; 297 298 Report.Result; 299 300end C460001; 301