1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
|
-- C460001.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.
--
-- 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;
|
