1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--              S Y S T E M . S T A N D A R D _ L I B R A R Y               --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2020, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- GNAT was originally developed  by the GNAT team at  New York University. --
28-- Extensive contributions were provided by Ada Core Technologies Inc.      --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This package is included in all programs. It contains declarations that
33--  are required to be part of every Ada program. A special mechanism is
34--  required to ensure that these are loaded, since it may be the case in
35--  some programs that the only references to these required packages are
36--  from C code or from code generated directly by Gigi, and in both cases
37--  the binder is not aware of such references.
38
39--  System.Standard_Library also includes data that must be present in every
40--  program, in particular data for all the standard exceptions, and also some
41--  subprograms that must be present in every program.
42
43--  The binder unconditionally includes s-stalib.ali, which ensures that this
44--  package and the packages it references are included in all Ada programs,
45--  together with the included data.
46
47pragma Compiler_Unit_Warning;
48
49with Ada.Unchecked_Conversion;
50
51package System.Standard_Library is
52
53   --  Historical note: pragma Preelaborate was surrounded by a pair of pragma
54   --  Warnings (Off/On) to circumvent a bootstrap issue.
55
56   pragma Preelaborate;
57
58   subtype Big_String is String (1 .. Positive'Last);
59   pragma Suppress_Initialization (Big_String);
60   --  Type used to obtain string access to given address. Initialization is
61   --  suppressed, since we never want to have variables of this type, and
62   --  we never want to attempt initialiazation of virtual variables of this
63   --  type (e.g. when pragma Normalize_Scalars is used).
64
65   type Big_String_Ptr is access all Big_String;
66   for Big_String_Ptr'Storage_Size use 0;
67   --  We use this access type to pass a pointer to an area of storage to be
68   --  accessed as a string. Of course when this pointer is used, it is the
69   --  responsibility of the accessor to ensure proper bounds. The storage
70   --  size clause ensures we do not allocate variables of this type.
71
72   function To_Ptr is
73     new Ada.Unchecked_Conversion (System.Address, Big_String_Ptr);
74
75   -------------------------------------
76   -- Exception Declarations and Data --
77   -------------------------------------
78
79   type Raise_Action is access procedure;
80   pragma Favor_Top_Level (Raise_Action);
81   --  A pointer to a procedure used in the Raise_Hook field
82
83   type Exception_Data;
84   type Exception_Data_Ptr is access all Exception_Data;
85   --  An equivalent of Exception_Id that is public
86
87   --  The following record defines the underlying representation of exceptions
88
89   --  WARNING: Any changes to this may need to be reflected in the following
90   --  locations in the compiler and runtime code:
91
92   --    1. The Internal_Exception routine in s-exctab.adb
93   --    2. The processing in gigi that tests Not_Handled_By_Others
94   --    3. Expand_N_Exception_Declaration in Exp_Ch11
95   --    4. The construction of the exception type in Cstand
96
97   type Exception_Data is record
98      Not_Handled_By_Others : Boolean;
99      --  Normally set False, indicating that the exception is handled in the
100      --  usual way by others (i.e. an others handler handles the exception).
101      --  Set True to indicate that this exception is not caught by others
102      --  handlers, but must be explicitly named in a handler. This latter
103      --  setting is currently used by the Abort_Signal.
104
105      Lang : Character;
106      --  A character indicating the language raising the exception.
107      --  Set to "A" for exceptions defined by an Ada program.
108      --  Set to "C" for imported C++ exceptions.
109
110      Name_Length : Natural;
111      --  Length of fully expanded name of exception
112
113      Full_Name : System.Address;
114      --  Fully expanded name of exception, null terminated
115      --  You can use To_Ptr to convert this to a string.
116
117      HTable_Ptr : Exception_Data_Ptr;
118      --  Hash table pointer used to link entries together in the hash table
119      --  built (by Register_Exception in s-exctab.adb) for converting between
120      --  identities and names.
121
122      Foreign_Data : Address;
123      --  Data for imported exceptions. Not used in the Ada case. This
124      --  represents the address of the RTTI for the C++ case.
125
126      Raise_Hook : Raise_Action;
127      --  This field can be used to place a "hook" on an exception. If the
128      --  value is non-null, then it points to a procedure which is called
129      --  whenever the exception is raised. This call occurs immediately,
130      --  before any other actions taken by the raise (and in particular
131      --  before any unwinding of the stack occurs).
132   end record;
133
134   --  Definitions for standard predefined exceptions defined in Standard,
135
136   --  Why are the NULs necessary here, seems like they should not be
137   --  required, since Gigi is supposed to add a Nul to each name ???
138
139   Constraint_Error_Name : constant String := "CONSTRAINT_ERROR" & ASCII.NUL;
140   Program_Error_Name    : constant String := "PROGRAM_ERROR"    & ASCII.NUL;
141   Storage_Error_Name    : constant String := "STORAGE_ERROR"    & ASCII.NUL;
142   Tasking_Error_Name    : constant String := "TASKING_ERROR"    & ASCII.NUL;
143   Abort_Signal_Name     : constant String := "_ABORT_SIGNAL"    & ASCII.NUL;
144
145   Numeric_Error_Name    : constant String := "NUMERIC_ERROR"    & ASCII.NUL;
146   --  This is used only in the Ada 83 case, but it is not worth having a
147   --  separate version of s-stalib.ads for use in Ada 83 mode.
148
149   Constraint_Error_Def : aliased Exception_Data :=
150     (Not_Handled_By_Others => False,
151      Lang                  => 'A',
152      Name_Length           => Constraint_Error_Name'Length,
153      Full_Name             => Constraint_Error_Name'Address,
154      HTable_Ptr            => null,
155      Foreign_Data          => Null_Address,
156      Raise_Hook            => null);
157
158   Numeric_Error_Def : aliased Exception_Data :=
159     (Not_Handled_By_Others => False,
160      Lang                  => 'A',
161      Name_Length           => Numeric_Error_Name'Length,
162      Full_Name             => Numeric_Error_Name'Address,
163      HTable_Ptr            => null,
164      Foreign_Data          => Null_Address,
165      Raise_Hook            => null);
166
167   Program_Error_Def : aliased Exception_Data :=
168     (Not_Handled_By_Others => False,
169      Lang                  => 'A',
170      Name_Length           => Program_Error_Name'Length,
171      Full_Name             => Program_Error_Name'Address,
172      HTable_Ptr            => null,
173      Foreign_Data          => Null_Address,
174      Raise_Hook            => null);
175
176   Storage_Error_Def : aliased Exception_Data :=
177     (Not_Handled_By_Others => False,
178      Lang                  => 'A',
179      Name_Length           => Storage_Error_Name'Length,
180      Full_Name             => Storage_Error_Name'Address,
181      HTable_Ptr            => null,
182      Foreign_Data          => Null_Address,
183      Raise_Hook            => null);
184
185   Tasking_Error_Def : aliased Exception_Data :=
186     (Not_Handled_By_Others => False,
187      Lang                  => 'A',
188      Name_Length           => Tasking_Error_Name'Length,
189      Full_Name             => Tasking_Error_Name'Address,
190      HTable_Ptr            => null,
191      Foreign_Data          => Null_Address,
192      Raise_Hook            => null);
193
194   Abort_Signal_Def : aliased Exception_Data :=
195     (Not_Handled_By_Others => True,
196      Lang                  => 'A',
197      Name_Length           => Abort_Signal_Name'Length,
198      Full_Name             => Abort_Signal_Name'Address,
199      HTable_Ptr            => null,
200      Foreign_Data          => Null_Address,
201      Raise_Hook            => null);
202
203   pragma Export (C, Constraint_Error_Def, "constraint_error");
204   pragma Export (C, Numeric_Error_Def,    "numeric_error");
205   pragma Export (C, Program_Error_Def,    "program_error");
206   pragma Export (C, Storage_Error_Def,    "storage_error");
207   pragma Export (C, Tasking_Error_Def,    "tasking_error");
208   pragma Export (C, Abort_Signal_Def,     "_abort_signal");
209
210   Local_Partition_ID : Natural := 0;
211   --  This variable contains the local Partition_ID that will be used when
212   --  building exception occurrences. In distributed mode, it will be
213   --  set by each partition to the correct value during the elaboration.
214
215   type Exception_Trace_Kind is
216     (RM_Convention,
217      --  No particular trace is requested, only unhandled exceptions
218      --  in the environment task (following the RM) will be printed.
219      --  This is the default behavior.
220
221      Every_Raise,
222      --  Denotes the initial raise event for any exception occurrence, either
223      --  explicit or due to a specific language rule, within the context of a
224      --  task or not.
225
226      Unhandled_Raise,
227      --  Denotes the raise events corresponding to exceptions for which there
228      --  is no user defined handler. This includes unhandled exceptions in
229      --  task bodies.
230
231      Unhandled_Raise_In_Main
232      --  Same as Unhandled_Raise, except exceptions in task bodies are not
233      --  included. Same as RM_Convention, except (1) the message is printed as
234      --  soon as the environment task completes due to an unhandled exception
235      --  (before awaiting the termination of dependent tasks, and before
236      --  library-level finalization), and (2) a symbolic traceback is given
237      --  if possible. This is the default behavior if the binder switch -E is
238      --  used.
239     );
240   --  Provide a way to denote different kinds of automatic traces related
241   --  to exceptions that can be requested.
242
243   Exception_Trace : Exception_Trace_Kind := RM_Convention;
244   pragma Atomic (Exception_Trace);
245   --  By default, follow the RM convention
246
247   -----------------
248   -- Subprograms --
249   -----------------
250
251   procedure Abort_Undefer_Direct;
252   pragma Inline (Abort_Undefer_Direct);
253   --  A little procedure that just calls Abort_Undefer.all, for use in
254   --  clean up procedures, which only permit a simple subprogram name.
255
256   procedure Adafinal;
257   --  Performs the Ada Runtime finalization the first time it is invoked.
258   --  All subsequent calls are ignored.
259
260end System.Standard_Library;
261