1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT COMPILER COMPONENTS                         --
4--                                                                          --
5--                                T Y P E S                                 --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 1992-2021, 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.  See the GNU General Public License --
17-- for  more details.  You should have  received  a copy of the GNU General --
18-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
19-- http://www.gnu.org/licenses for a complete copy of the license.          --
20--                                                                          --
21-- GNAT was originally developed  by the GNAT team at  New York University. --
22-- Extensive contributions were provided by Ada Core Technologies Inc.      --
23--                                                                          --
24------------------------------------------------------------------------------
25
26--  This package contains host independent type definitions which are used
27--  in more than one unit in the compiler. They are gathered here for easy
28--  reference, although in some cases the full description is found in the
29--  relevant module which implements the definition. The main reason that they
30--  are not in their "natural" specs is that this would cause a lot of inter-
31--  spec dependencies, and in particular some awkward circular dependencies
32--  would have to be dealt with.
33
34--  WARNING: There is a C version of this package. Any changes to this source
35--  file must be properly reflected in the C header file types.h
36
37--  Note: the declarations in this package reflect an expectation that the host
38--  machine has an efficient integer base type with a range at least 32 bits
39--  2s-complement. If there are any machines for which this is not a correct
40--  assumption, a significant number of changes will be required.
41
42with System;
43with Unchecked_Conversion;
44with Unchecked_Deallocation;
45
46package Types is
47   pragma Preelaborate;
48
49   -------------------------------
50   -- General Use Integer Types --
51   -------------------------------
52
53   type Int is range -2 ** 31 .. +2 ** 31 - 1;
54   --  Signed 32-bit integer
55
56   subtype Nat is Int range 0 .. Int'Last;
57   --  Non-negative Int values
58
59   subtype Pos is Int range 1 .. Int'Last;
60   --  Positive Int values
61
62   subtype Nonzero_Int is Int with Predicate => Nonzero_Int /= 0;
63
64   type Int_64 is range -2 ** 63 .. +2 ** 63 - 1;
65   --  Signed 64-bit integer
66
67   subtype Nat_64 is Int_64 range 0 .. Int_64'Last;
68   subtype Pos_64 is Int_64 range 1 .. Int_64'Last;
69   subtype Nonzero_Int_64 is Int_64 with Predicate => Nonzero_Int_64 /= 0;
70
71   type Word is mod 2 ** 32;
72   --  Unsigned 32-bit integer
73
74   type Short is range -32768 .. +32767;
75   for Short'Size use 16;
76   --  16-bit signed integer
77
78   type Byte is mod 2 ** 8;
79   for Byte'Size use 8;
80   --  8-bit unsigned integer
81
82   type size_t is mod 2 ** Standard'Address_Size;
83   --  Memory size value, for use in calls to C routines
84
85   --------------------------------------
86   -- 8-Bit Character and String Types --
87   --------------------------------------
88
89   --  We use Standard.Character and Standard.String freely, since we are
90   --  compiling ourselves, and we properly implement the required 8-bit
91   --  character code as required in Ada 95. This section defines a few
92   --  general use constants and subtypes.
93
94   EOF : constant Character := ASCII.SUB;
95   --  The character SUB (16#1A#) is used in DOS and other systems derived
96   --  from DOS (XP, NT etc) to signal the end of a text file. Internally
97   --  all source files are ended by an EOF character, even on Unix systems.
98   --  An EOF character acts as the end of file only as the last character
99   --  of a source buffer, in any other position, it is treated as a blank
100   --  if it appears between tokens, and as an illegal character otherwise.
101   --  This makes life easier dealing with files that originated from DOS,
102   --  including concatenated files with interspersed EOF characters.
103
104   subtype Graphic_Character is Character range ' ' .. '~';
105   --  Graphic characters, as defined in ARM
106
107   subtype Line_Terminator is Character range ASCII.LF .. ASCII.CR;
108   --  Line terminator characters (LF, VT, FF, CR). For further details, see
109   --  the extensive discussion of line termination in the Sinput spec.
110
111   subtype Upper_Half_Character is
112     Character range Character'Val (16#80#) .. Character'Val (16#FF#);
113   --  8-bit Characters with the upper bit set
114
115   type Character_Ptr    is access all Character;
116   type String_Ptr       is access all String;
117   type String_Ptr_Const is access constant String;
118   --  Standard character and string pointers
119
120   procedure Free is new Unchecked_Deallocation (String, String_Ptr);
121   --  Procedure for freeing dynamically allocated String values
122
123   subtype Big_String is String (Positive);
124   type Big_String_Ptr is access all Big_String;
125   --  Virtual type for handling imported big strings. Note that we should
126   --  never have any allocators for this type, but we don't give a storage
127   --  size of zero, since there are legitimate deallocations going on.
128
129   function To_Big_String_Ptr is
130     new Unchecked_Conversion (System.Address, Big_String_Ptr);
131   --  Used to obtain Big_String_Ptr values from external addresses
132
133   subtype Word_Hex_String is String (1 .. 8);
134   --  Type used to represent Word value as 8 hex digits, with lower case
135   --  letters for the alphabetic cases.
136
137   function Get_Hex_String (W : Word) return Word_Hex_String;
138   --  Convert word value to 8-character hex string
139
140   -----------------------------------------
141   -- Types Used for Text Buffer Handling --
142   -----------------------------------------
143
144   --  We cannot use type String for text buffers, since we must use the
145   --  standard 32-bit integer as an index value, since we count on all index
146   --  values being the same size.
147
148   type Text_Ptr is new Int;
149   --  Type used for subscripts in text buffer
150
151   type Text_Buffer is array (Text_Ptr range <>) of Character;
152   --  Text buffer used to hold source file or library information file
153
154   type Text_Buffer_Ptr is access all Text_Buffer;
155   --  Text buffers for input files are allocated dynamically and this type
156   --  is used to reference these text buffers.
157
158   procedure Free is new Unchecked_Deallocation (Text_Buffer, Text_Buffer_Ptr);
159   --  Procedure for freeing dynamically allocated text buffers
160
161   ------------------------------------------
162   -- Types Used for Source Input Handling --
163   ------------------------------------------
164
165   type Logical_Line_Number is range 0 .. Int'Last;
166   for Logical_Line_Number'Size use 32;
167   --  Line number type, used for storing logical line numbers (i.e. line
168   --  numbers that include effects of any Source_Reference pragmas in the
169   --  source file). The value zero indicates a line containing a source
170   --  reference pragma.
171
172   No_Line_Number : constant Logical_Line_Number := 0;
173   --  Special value used to indicate no line number
174
175   type Physical_Line_Number is range 1 .. Int'Last;
176   for Physical_Line_Number'Size use 32;
177   --  Line number type, used for storing physical line numbers (i.e. line
178   --  numbers in the physical file being compiled, unaffected by the presence
179   --  of source reference pragmas).
180
181   type Column_Number is range 0 .. 32767;
182   for Column_Number'Size use 16;
183   --  Column number (assume that 2**15 - 1 is large enough). The range for
184   --  this type is used to compute Hostparm.Max_Line_Length. See also the
185   --  processing for -gnatyM in Stylesw).
186
187   No_Column_Number : constant Column_Number := 0;
188   --  Special value used to indicate no column number
189
190   Source_Align : constant := 2 ** 12;
191   --  Alignment requirement for source buffers (by keeping source buffers
192   --  aligned, we can optimize the implementation of Get_Source_File_Index.
193   --  See this routine in Sinput for details.
194
195   subtype Source_Buffer is Text_Buffer;
196   --  Type used to store text of a source file. The buffer for the main
197   --  source (the source specified on the command line) has a lower bound
198   --  starting at zero. Subsequent subsidiary sources have lower bounds
199   --  which are one greater than the previous upper bound, rounded up to
200   --  a multiple of Source_Align.
201
202   type Source_Buffer_Ptr_Var is access all Source_Buffer;
203   type Source_Buffer_Ptr is access constant Source_Buffer;
204   --  Pointer to source buffer. Source_Buffer_Ptr_Var is used for allocation
205   --  and deallocation; Source_Buffer_Ptr is used for all other uses of source
206   --  buffers.
207
208   function Null_Source_Buffer_Ptr (X : Source_Buffer_Ptr) return Boolean;
209   --  True if X = null
210
211   function Source_Buffer_Ptr_Equal (X, Y : Source_Buffer_Ptr) return Boolean
212     renames "=";
213   --  Squirrel away the predefined "=", for use in Null_Source_Buffer_Ptr.
214   --  Do not call this elsewhere.
215
216   function "=" (X, Y : Source_Buffer_Ptr) return Boolean is abstract;
217   --  Make "=" abstract. Note that this makes "/=" abstract as well. This is a
218   --  vestige of the zero-origin array indexing we used to use, where "=" is
219   --  always wrong (including the one in Null_Source_Buffer_Ptr). We keep this
220   --  just because we never need to compare Source_Buffer_Ptrs other than to
221   --  null.
222
223   subtype Source_Ptr is Text_Ptr;
224   --  Type used to represent a source location, which is a subscript of a
225   --  character in the source buffer. As noted above, different source buffers
226   --  have different ranges, so it is possible to tell from a Source_Ptr value
227   --  which source it refers to. Note that negative numbers are allowed to
228   --  accommodate the following special values.
229
230   type Source_Span is record
231      Ptr, First, Last : Source_Ptr;
232   end record;
233   --  Type used to represent a source span, consisting in a main location Ptr,
234   --  with a First and Last location, such that Ptr in First .. Last
235
236   function To_Span (Loc : Source_Ptr) return Source_Span is ((others => Loc));
237   function To_Span (Ptr, First, Last : Source_Ptr) return Source_Span is
238     ((Ptr, First, Last));
239
240   No_Location : constant Source_Ptr := -1;
241   --  Value used to indicate no source position set in a node. A test for a
242   --  Source_Ptr value being > No_Location is the approved way to test for a
243   --  standard value that does not include No_Location or any of the following
244   --  special definitions. One important use of No_Location is to label
245   --  generated nodes that we don't want the debugger to see in normal mode
246   --  (very often we conditionalize so that we set No_Location in normal mode
247   --  and the corresponding source line in -gnatD mode).
248
249   Standard_Location : constant Source_Ptr := -2;
250   --  Used for all nodes in the representation of package Standard other than
251   --  nodes representing the contents of Standard.ASCII. Note that testing for
252   --  a value being <= Standard_Location tests for both Standard_Location and
253   --  for Standard_ASCII_Location.
254
255   Standard_ASCII_Location : constant Source_Ptr := -3;
256   --  Used for all nodes in the presentation of package Standard.ASCII
257
258   System_Location : constant Source_Ptr := -4;
259   --  Used to identify locations of pragmas scanned by Targparm, where we know
260   --  the location is in System, but we don't know exactly what line.
261
262   First_Source_Ptr : constant Source_Ptr := 0;
263   --  Starting source pointer index value for first source program
264
265   -------------------------------------
266   -- Range Definitions for Tree Data --
267   -------------------------------------
268
269   --  The tree has fields that can hold any of the following types:
270
271   --    Pointers to other tree nodes (type Node_Id)
272   --    List pointers (type List_Id)
273   --    Element list pointers (type Elist_Id)
274   --    Names (type Name_Id)
275   --    Strings (type String_Id)
276   --    Universal integers (type Uint)
277   --    Universal reals (type Ureal)
278
279   --  These types are represented as integer indices into various tables.
280   --  However, they should be treated as private, except in a few documented
281   --  cases. In particular it is usually inappropriate to perform arithmetic
282   --  operations using these types. One exception is in computing hash
283   --  functions of these types.
284
285   --  In most contexts, the strongly typed interface determines which of these
286   --  types is present. However, there are some situations (involving untyped
287   --  traversals of the tree), where it is convenient to be easily able to
288   --  distinguish these values. The underlying representation in all cases is
289   --  an integer type Union_Id, and we ensure that the range of the various
290   --  possible values for each of the above types is disjoint (except that
291   --  List_Id and Node_Id overlap at Empty) so that this distinction is
292   --  possible.
293
294   --  Note: it is also helpful for debugging purposes to make these ranges
295   --  distinct. If a bug leads to misidentification of a value, then it will
296   --  typically result in an out of range value and a Constraint_Error.
297
298   --  The range of Node_Id is most of the nonnegative integers. The other
299   --  ranges are negative. Uint has a very large range, because a substantial
300   --  part of this range is used to store direct values; see Uintp for
301   --  details. The other types have 100 million values, which should be
302   --  plenty.
303
304   type Union_Id is new Int;
305   --  The type in the tree for a union of possible ID values
306
307   --  Following are the Low and High bounds of the various ranges.
308
309   List_Low_Bound : constant := -099_999_999;
310   --  The List_Id values are subscripts into an array of list headers which
311   --  has List_Low_Bound as its lower bound.
312
313   List_High_Bound : constant := 0;
314   --  Maximum List_Id subscript value. The ranges of List_Id and Node_Id
315   --  overlap by one element (with value zero), which is used both for the
316   --  Empty node, and for No_List. The fact that the same value is used is
317   --  convenient because it means that the default value of Empty applies to
318   --  both nodes and lists, and also is more efficient to test for.
319
320   Node_Low_Bound : constant := 0;
321   --  The tree Id values start at zero, because we use zero for Empty (to
322   --  allow a zero test for Empty).
323
324   Node_High_Bound : constant := 1_999_999_999;
325
326   Elist_Low_Bound : constant := -199_999_999;
327   --  The Elist_Id values are subscripts into an array of elist headers which
328   --  has Elist_Low_Bound as its lower bound.
329
330   Elist_High_Bound : constant := -100_000_000;
331
332   Elmt_Low_Bound : constant := -299_999_999;
333   --  Low bound of element Id values. The use of these values is internal to
334   --  the Elists package, but the definition of the range is included here
335   --  since it must be disjoint from other Id values. The Elmt_Id values are
336   --  subscripts into an array of list elements which has this as lower bound.
337
338   Elmt_High_Bound : constant := -200_000_000;
339
340   Names_Low_Bound : constant := -399_999_999;
341
342   Names_High_Bound : constant := -300_000_000;
343
344   Strings_Low_Bound : constant := -499_999_999;
345
346   Strings_High_Bound : constant := -400_000_000;
347
348   Ureal_Low_Bound : constant := -599_999_999;
349
350   Ureal_High_Bound : constant := -500_000_000;
351
352   Uint_Low_Bound : constant := -2_100_000_000;
353   --  Low bound for Uint values
354
355   Uint_Table_Start : constant := -699_999_999;
356   --  Location where table entries for universal integers start (see
357   --  Uintp spec for details of the representation of Uint values).
358
359   Uint_High_Bound : constant := -600_000_000;
360
361   --  The following subtype definitions are used to provide convenient names
362   --  for membership tests on Int values to see what data type range they
363   --  lie in. Such tests appear only in the lowest level packages.
364
365   subtype List_Range      is Union_Id
366     range List_Low_Bound    .. List_High_Bound;
367
368   subtype Node_Range      is Union_Id
369     range Node_Low_Bound    .. Node_High_Bound;
370
371   subtype Elist_Range     is Union_Id
372     range Elist_Low_Bound   .. Elist_High_Bound;
373
374   subtype Elmt_Range      is Union_Id
375     range Elmt_Low_Bound    .. Elmt_High_Bound;
376
377   subtype Names_Range     is Union_Id
378     range Names_Low_Bound   .. Names_High_Bound;
379
380   subtype Strings_Range   is Union_Id
381     range Strings_Low_Bound .. Strings_High_Bound;
382
383   subtype Uint_Range      is Union_Id
384     range Uint_Low_Bound    .. Uint_High_Bound;
385
386   subtype Ureal_Range     is Union_Id
387     range Ureal_Low_Bound   .. Ureal_High_Bound;
388
389   -----------------------------
390   -- Types for Atree Package --
391   -----------------------------
392
393   --  Node_Id values are used to identify nodes in the tree. They are
394   --  subscripts into the Nodes table declared in package Atree. Note that
395   --  the special values Empty and Error are subscripts into this table.
396   --  See package Atree for further details.
397
398   type Node_Id is range Node_Low_Bound .. Node_High_Bound with Size => 32;
399   --  Type used to identify nodes in the tree
400
401   subtype Entity_Id is Node_Id;
402   --  A synonym for node types, used in the Einfo package to refer to nodes
403   --  that are entities (i.e. nodes with an Nkind of N_Defining_xxx). All such
404   --  nodes are extended nodes and these are the only extended nodes, so that
405   --  in practice entity and extended nodes are synonymous.
406
407   subtype Node_Or_Entity_Id is Node_Id;
408   --  A synonym for node types, used in cases where a given value may be used
409   --  to represent either a node or an entity. We like to minimize such uses
410   --  for obvious reasons of logical type consistency, but where such uses
411   --  occur, they should be documented by use of this type.
412
413   Empty : constant Node_Id := Node_Low_Bound;
414   --  Used to indicate null node. A node is actually allocated with this
415   --  Id value, so that Nkind (Empty) = N_Empty. Note that Node_Low_Bound
416   --  is zero, so Empty = No_List = zero.
417
418   Empty_List_Or_Node : constant := 0;
419   --  This constant is used in situations (e.g. initializing empty fields)
420   --  where the value set will be used to represent either an empty node or
421   --  a non-existent list, depending on the context.
422
423   Error : constant Node_Id := Node_Low_Bound + 1;
424   --  Used to indicate an error in the source program. A node is actually
425   --  allocated with this Id value, so that Nkind (Error) = N_Error.
426
427   Empty_Or_Error : constant Node_Id := Error;
428   --  Since Empty and Error are the first two Node_Id values, the test for
429   --  N <= Empty_Or_Error tests to see if N is Empty or Error. This definition
430   --  provides convenient self-documentation for such tests.
431
432   First_Node_Id  : constant Node_Id := Node_Low_Bound;
433   --  Subscript of first allocated node. Note that Empty and Error are both
434   --  allocated nodes, whose Nkind fields can be accessed without error.
435
436   ------------------------------
437   -- Types for Nlists Package --
438   ------------------------------
439
440   --  List_Id values are used to identify node lists stored in the tree, so
441   --  that each node can be on at most one such list (see package Nlists for
442   --  further details). Note that the special value Error_List is a subscript
443   --  in this table, but the value No_List is *not* a valid subscript, and any
444   --  attempt to apply list operations to No_List will cause a (detected)
445   --  error.
446
447   type List_Id is range List_Low_Bound .. List_High_Bound with Size => 32;
448   --  Type used to identify a node list
449
450   No_List : constant List_Id := List_High_Bound;
451   --  Used to indicate absence of a list. Note that the value is zero, which
452   --  is the same as Empty, which is helpful in initializing nodes where a
453   --  value of zero can represent either an empty node or an empty list.
454
455   Error_List : constant List_Id := List_Low_Bound;
456   --  Used to indicate that there was an error in the source program in a
457   --  context which would normally require a list. This node appears to be
458   --  an empty list to the list operations (a null list is actually allocated
459   --  which has this Id value).
460
461   First_List_Id : constant List_Id := Error_List;
462   --  Subscript of first allocated list header
463
464   ------------------------------
465   -- Types for Elists Package --
466   ------------------------------
467
468   --  Element list Id values are used to identify element lists stored outside
469   --  of the tree, allowing nodes to be members of more than one such list
470   --  (see package Elists for further details).
471
472   type Elist_Id is range Elist_Low_Bound .. Elist_High_Bound with Size => 32;
473   --  Type used to identify an element list (Elist header table subscript)
474
475   No_Elist : constant Elist_Id := Elist_Low_Bound;
476   --  Used to indicate absence of an element list. Note that this is not an
477   --  actual Elist header, so element list operations on this value are not
478   --  valid.
479
480   First_Elist_Id : constant Elist_Id := No_Elist + 1;
481   --  Subscript of first allocated Elist header
482
483   --  Element Id values are used to identify individual elements of an element
484   --  list (see package Elists for further details).
485
486   type Elmt_Id is range Elmt_Low_Bound .. Elmt_High_Bound;
487   --  Type used to identify an element list
488
489   No_Elmt : constant Elmt_Id := Elmt_Low_Bound;
490   --  Used to represent empty element
491
492   First_Elmt_Id : constant Elmt_Id := No_Elmt + 1;
493   --  Subscript of first allocated Elmt table entry
494
495   -------------------------------
496   -- Types for Stringt Package --
497   -------------------------------
498
499   --  String_Id values are used to identify entries in the strings table. They
500   --  are subscripts into the Strings table defined in package Stringt.
501
502   type String_Id is range Strings_Low_Bound .. Strings_High_Bound
503     with Size => 32;
504   --  Type used to identify entries in the strings table
505
506   No_String : constant String_Id := Strings_Low_Bound;
507   --  Used to indicate missing string Id. Note that the value zero is used
508   --  to indicate a missing data value for all the Int types in this section.
509
510   First_String_Id : constant String_Id := No_String + 1;
511   --  First subscript allocated in string table
512
513   -------------------------
514   -- Character Code Type --
515   -------------------------
516
517   --  The type Char is used for character data internally in the compiler, but
518   --  character codes in the source are represented by the Char_Code type.
519   --  Each character literal in the source is interpreted as being one of the
520   --  16#7FFF_FFFF# possible Wide_Wide_Character codes, and a unique Integer
521   --  value is assigned, corresponding to the UTF-32 value, which also
522   --  corresponds to the Pos value in the Wide_Wide_Character type, and also
523   --  corresponds to the Pos value in the Wide_Character and Character types
524   --  for values that are in appropriate range. String literals are similarly
525   --  interpreted as a sequence of such codes.
526
527   type Char_Code_Base is mod 2 ** 32;
528   for Char_Code_Base'Size use 32;
529
530   subtype Char_Code is Char_Code_Base range 0 .. 16#7FFF_FFFF#;
531   for Char_Code'Value_Size use 32;
532   for Char_Code'Object_Size use 32;
533
534   function Get_Char_Code (C : Character) return Char_Code;
535   pragma Inline (Get_Char_Code);
536   --  Function to obtain internal character code from source character. For
537   --  the moment, the internal character code is simply the Pos value of the
538   --  input source character, but we provide this interface for possible
539   --  later support of alternative character sets.
540
541   function In_Character_Range (C : Char_Code) return Boolean;
542   pragma Inline (In_Character_Range);
543   --  Determines if the given character code is in range of type Character,
544   --  and if so, returns True. If not, returns False.
545
546   function In_Wide_Character_Range (C : Char_Code) return Boolean;
547   pragma Inline (In_Wide_Character_Range);
548   --  Determines if the given character code is in range of the type
549   --  Wide_Character, and if so, returns True. If not, returns False.
550
551   function Get_Character (C : Char_Code) return Character;
552   pragma Inline (Get_Character);
553   --  For a character C that is in Character range (see above function), this
554   --  function returns the corresponding Character value. It is an error to
555   --  call Get_Character if C is not in Character range.
556
557   function Get_Wide_Character (C : Char_Code) return Wide_Character;
558   --  For a character C that is in Wide_Character range (see above function),
559   --  this function returns the corresponding Wide_Character value. It is an
560   --  error to call Get_Wide_Character if C is not in Wide_Character range.
561
562   ---------------------------------------
563   -- Types used for Library Management --
564   ---------------------------------------
565
566   type Unit_Number_Type is new Int range -1 .. Int'Last;
567   --  Unit number. The main source is unit 0, and subsidiary sources have
568   --  non-zero numbers starting with 1. Unit numbers are used to index the
569   --  Units table in package Lib.
570
571   Main_Unit : constant Unit_Number_Type := 0;
572   --  Unit number value for main unit
573
574   No_Unit : constant Unit_Number_Type := -1;
575   --  Special value used to signal no unit
576
577   type Source_File_Index is new Int range -1 .. Int'Last;
578   --  Type used to index the source file table (see package Sinput)
579
580   No_Source_File : constant Source_File_Index := 0;
581   --  Value used to indicate no source file present
582
583   No_Access_To_Source_File : constant Source_File_Index := -1;
584   --  Value used to indicate a source file is present but unreadable
585
586   -----------------------------------
587   -- Representation of Time Stamps --
588   -----------------------------------
589
590   --  All compiled units are marked with a time stamp which is derived from
591   --  the source file (we assume that the host system has the concept of a
592   --  file time stamp which is modified when a file is modified). These
593   --  time stamps are used to ensure consistency of the set of units that
594   --  constitutes a library. Time stamps are 14-character strings with
595   --  with the following format:
596
597   --     YYYYMMDDHHMMSS
598
599   --       YYYY   year
600   --       MM     month (2 digits 01-12)
601   --       DD     day (2 digits 01-31)
602   --       HH     hour (2 digits 00-23)
603   --       MM     minutes (2 digits 00-59)
604   --       SS     seconds (2 digits 00-59)
605
606   --  In the case of Unix systems (and other systems which keep the time in
607   --  GMT), the time stamp is the GMT time of the file, not the local time.
608   --  This solves problems in using libraries across networks with clients
609   --  spread across multiple time-zones.
610
611   Time_Stamp_Length : constant := 14;
612   --  Length of time stamp value
613
614   subtype Time_Stamp_Index is Natural range 1 .. Time_Stamp_Length;
615   type Time_Stamp_Type is new String (Time_Stamp_Index);
616   --  Type used to represent time stamp
617
618   Empty_Time_Stamp : constant Time_Stamp_Type := (others => ' ');
619   --  Value representing an empty or missing time stamp. Looks less than any
620   --  real time stamp if two time stamps are compared. Note that although this
621   --  is not private, clients should not rely on the exact way in which this
622   --  string is represented, and instead should use the subprograms below.
623
624   Dummy_Time_Stamp : constant Time_Stamp_Type := (others => '0');
625   --  This is used for dummy time stamp values used in the D lines for
626   --  non-existent files, and is intended to be an impossible value.
627
628   function "="  (Left, Right : Time_Stamp_Type) return Boolean;
629   function "<=" (Left, Right : Time_Stamp_Type) return Boolean;
630   function ">=" (Left, Right : Time_Stamp_Type) return Boolean;
631   function "<"  (Left, Right : Time_Stamp_Type) return Boolean;
632   function ">"  (Left, Right : Time_Stamp_Type) return Boolean;
633   --  Comparison functions on time stamps. Note that two time stamps are
634   --  defined as being equal if they have the same day/month/year and the
635   --  hour/minutes/seconds values are within 2 seconds of one another. This
636   --  deals with rounding effects in library file time stamps caused by
637   --  copying operations during installation. We have particularly noticed
638   --  that WinNT seems susceptible to such changes.
639   --
640   --  Note: the Empty_Time_Stamp value looks equal to itself, and less than
641   --  any non-empty time stamp value.
642
643   procedure Split_Time_Stamp
644     (TS      : Time_Stamp_Type;
645      Year    : out Nat;
646      Month   : out Nat;
647      Day     : out Nat;
648      Hour    : out Nat;
649      Minutes : out Nat;
650      Seconds : out Nat);
651   --  Given a time stamp, decompose it into its components
652
653   procedure Make_Time_Stamp
654     (Year    : Nat;
655      Month   : Nat;
656      Day     : Nat;
657      Hour    : Nat;
658      Minutes : Nat;
659      Seconds : Nat;
660      TS      : out Time_Stamp_Type);
661   --  Given the components of a time stamp, initialize the value
662
663   -------------------------------------
664   -- Types used for Check Management --
665   -------------------------------------
666
667   type Check_Id is new Nat;
668   --  Type used to represent a check id
669
670   No_Check_Id : constant := 0;
671   --  Check_Id value used to indicate no check
672
673   Access_Check               : constant :=  1;
674   Accessibility_Check        : constant :=  2;
675   Alignment_Check            : constant :=  3;
676   Allocation_Check           : constant :=  4;
677   Atomic_Synchronization     : constant :=  5;
678   Characters_Assertion_Check : constant :=  6;
679   Containers_Assertion_Check : constant :=  7;
680   Discriminant_Check         : constant :=  8;
681   Division_Check             : constant :=  9;
682   Duplicated_Tag_Check       : constant := 10;
683   Elaboration_Check          : constant := 11;
684   Index_Check                : constant := 12;
685   Interfaces_Assertion_Check : constant := 13;
686   IO_Assertion_Check         : constant := 14;
687   Length_Check               : constant := 15;
688   Numerics_Assertion_Check   : constant := 16;
689   Overflow_Check             : constant := 17;
690   Predicate_Check            : constant := 18;
691   Program_Error_Check        : constant := 19;
692   Range_Check                : constant := 20;
693   Storage_Check              : constant := 21;
694   Strings_Assertion_Check    : constant := 22;
695   System_Assertion_Check     : constant := 23;
696   Tag_Check                  : constant := 24;
697   Validity_Check             : constant := 25;
698   Container_Checks           : constant := 26;
699   Tampering_Check            : constant := 27;
700   Tasking_Check              : constant := 28;
701   --  Values used to represent individual predefined checks (including the
702   --  setting of Atomic_Synchronization, which is implemented internally using
703   --  a "check" whose name is Atomic_Synchronization).
704
705   All_Checks : constant := 29;
706   --  Value used to represent All_Checks value
707
708   subtype Predefined_Check_Id is Check_Id range 1 .. All_Checks;
709   --  Subtype for predefined checks, including All_Checks
710
711   --  The following array contains an entry for each recognized check name
712   --  for pragma Suppress. It is used to represent current settings of scope
713   --  based suppress actions from pragma Suppress or command line settings.
714
715   --  Note: when Suppress_Array (All_Checks) is True, then generally all other
716   --  specific check entries are set True, except for the Elaboration_Check
717   --  entry which is set only if an explicit Suppress for this check is given.
718   --  The reason for this non-uniformity is that we do not want All_Checks to
719   --  suppress elaboration checking when using the static elaboration model.
720   --  We recognize only an explicit suppress of Elaboration_Check as a signal
721   --  that the static elaboration checking should skip a compile time check.
722
723   type Suppress_Array is array (Predefined_Check_Id) of Boolean;
724   pragma Pack (Suppress_Array);
725
726   --  To add a new check type to GNAT, the following steps are required:
727
728   --    1.  Add an entry to Snames spec for the new name
729   --    2.  Add an entry to the definition of Check_Id above (very important:
730   --        these definitions should be in the same order in Snames and here)
731   --    3.  Add a new function to Checks to handle the new check test
732   --    4.  Add a new Do_xxx_Check flag to Sinfo (if required)
733   --    5.  Add appropriate checks for the new test
734
735   --  The following provides precise details on the mode used to generate
736   --  code for intermediate operations in expressions for signed integer
737   --  arithmetic (and how to generate overflow checks if enabled). Note
738   --  that this only affects handling of intermediate results. The final
739   --  result must always fit within the target range, and if overflow
740   --  checking is enabled, the check on the final result is against this
741   --  target range.
742
743   type Overflow_Mode_Type is (
744      Not_Set,
745      --  Dummy value used during initialization process to show that the
746      --  corresponding value has not yet been initialized.
747
748      Strict,
749      --  Operations are done in the base type of the subexpression. If
750      --  overflow checks are enabled, then the check is against the range
751      --  of this base type.
752
753      Minimized,
754      --  Where appropriate, intermediate arithmetic operations are performed
755      --  with an extended range, using Long_Long_Integer if necessary. If
756      --  overflow checking is enabled, then the check is against the range
757      --  of Long_Long_Integer.
758
759      Eliminated);
760      --  In this mode arbitrary precision arithmetic is used as needed to
761      --  ensure that it is impossible for intermediate arithmetic to cause an
762      --  overflow. In this mode, intermediate expressions are not affected by
763      --  the overflow checking mode, since overflows are eliminated.
764
765   subtype Minimized_Or_Eliminated is
766     Overflow_Mode_Type range Minimized .. Eliminated;
767   --  Define subtype so that clients don't need to know ordering. Note that
768   --  Overflow_Mode_Type is not marked as an ordered enumeration type.
769
770   --  The following structure captures the state of check suppression or
771   --  activation at a particular point in the program execution.
772
773   type Suppress_Record is record
774      Suppress : Suppress_Array;
775      --  Indicates suppression status of each possible check
776
777      Overflow_Mode_General : Overflow_Mode_Type;
778      --  This field indicates the mode for handling code generation and
779      --  overflow checking (if enabled) for intermediate expression values.
780      --  This applies to general expressions outside assertions.
781
782      Overflow_Mode_Assertions : Overflow_Mode_Type;
783      --  This field indicates the mode for handling code generation and
784      --  overflow checking (if enabled) for intermediate expression values.
785      --  This applies to any expression occurring inside assertions.
786   end record;
787
788   -----------------------------------
789   -- Global Exception Declarations --
790   -----------------------------------
791
792   --  This section contains declarations of exceptions that are used
793   --  throughout the compiler or in other GNAT tools.
794
795   Unrecoverable_Error : exception;
796   --  This exception is raised to immediately terminate the compilation of the
797   --  current source program. Used in situations where things are bad enough
798   --  that it doesn't seem worth continuing (e.g. max errors reached, or a
799   --  required file is not found). Also raised when the compiler finds itself
800   --  in trouble after an error (see Comperr).
801
802   Terminate_Program : exception;
803   --  This exception is raised to immediately terminate the tool being
804   --  executed. Each tool where this exception may be raised must have a
805   --  single exception handler that contains only a null statement and that is
806   --  the last statement of the program. If needed, procedure Set_Exit_Status
807   --  is called with the appropriate exit status before raising
808   --  Terminate_Program.
809
810   ---------------------------------
811   -- Parameter Mechanism Control --
812   ---------------------------------
813
814   --  Function and parameter entities have a field that records the passing
815   --  mechanism. See specification of Sem_Mech for full details. The following
816   --  subtype is used to represent values of this type:
817
818   subtype Mechanism_Type is Int range -2 .. Int'Last;
819   --  Type used to represent a mechanism value. This is a subtype rather than
820   --  a type to avoid some annoying processing problems with certain routines
821   --  in Einfo (processing them to create the corresponding C). The values in
822   --  the range -2 .. 0 are used to represent mechanism types declared as
823   --  named constants in the spec of Sem_Mech. Positive values are used for
824   --  the case of a pragma C_Pass_By_Copy that sets a threshold value for the
825   --  mechanism to be used. For example if pragma C_Pass_By_Copy (32) is given
826   --  then Default_C_Record_Mechanism is set to 32, and the meaning is to use
827   --  By_Reference if the size is greater than 32, and By_Copy otherwise.
828
829   ---------------------------------
830   -- Component_Alignment Control --
831   ---------------------------------
832
833   --  There are four types of alignment possible for array and record
834   --  types, and a field in the type entities contains a value of the
835   --  following type indicating which alignment choice applies. For full
836   --  details of the meaning of these alignment types, see description
837   --  of the Component_Alignment pragma.
838
839   type Component_Alignment_Kind is (
840      Calign_Default,          -- default alignment
841      Calign_Component_Size,   -- natural alignment for component size
842      Calign_Component_Size_4, -- natural for size <= 4, 4 for size >= 4
843      Calign_Storage_Unit);    -- all components byte aligned
844
845   -----------------------------------
846   -- Floating Point Representation --
847   -----------------------------------
848
849   type Float_Rep_Kind is (IEEE_Binary);
850   --  The only one supported now is IEEE 754p conforming binary format, but
851   --  other formats were supported in the past, and could conceivably be
852   --  supported in the future, so we keep this singleton enumeration type.
853
854   ----------------------------
855   -- Small_Paren_Count_Type --
856   ----------------------------
857
858   --  See Paren_Count in Atree for documentation
859
860   subtype Small_Paren_Count_Type is Nat range 0 .. 3;
861
862   ------------------------------
863   -- Run-Time Exception Codes --
864   ------------------------------
865
866   --  When the code generator generates a run-time exception, it provides a
867   --  reason code which is one of the following. This reason code is used to
868   --  select the appropriate run-time routine to be called, determining both
869   --  the exception to be raised, and the message text to be added.
870
871   --  The prefix CE/PE/SE indicates the exception to be raised
872   --    CE = Constraint_Error
873   --    PE = Program_Error
874   --    SE = Storage_Error
875
876   --  The remaining part of the name indicates the message text to be added,
877   --  where all letters are lower case, and underscores are converted to
878   --  spaces (for example CE_Invalid_Data adds the text "invalid data").
879
880   --  To add a new code, you need to do the following:
881
882   --    1. Assign a new number to the reason. Do not renumber existing codes,
883   --       since this causes compatibility/bootstrap issues, so always add the
884   --       new code at the end of the list.
885
886   --    2. Update the contents of the array Kind
887
888   --    3. Modify the corresponding definitions in types.h, including the
889   --       definition of last_reason_code.
890
891   --    4. Add the name of the routines in exp_ch11.Get_RT_Exception_Name
892
893   --    5. Add a new routine in Ada.Exceptions with the appropriate call and
894   --       static string constant. Note that there is more than one version
895   --       of a-except.adb which must be modified.
896
897   --  Note on ordering of references. For the tables in Ada.Exceptions units,
898   --  usually the ordering does not matter, and we use the same ordering as
899   --  is used here.
900
901   type RT_Exception_Code is
902     (CE_Access_Check_Failed,            -- 00
903      CE_Access_Parameter_Is_Null,       -- 01
904      CE_Discriminant_Check_Failed,      -- 02
905      CE_Divide_By_Zero,                 -- 03
906      CE_Explicit_Raise,                 -- 04
907      CE_Index_Check_Failed,             -- 05
908      CE_Invalid_Data,                   -- 06
909      CE_Length_Check_Failed,            -- 07
910      CE_Null_Exception_Id,              -- 08
911      CE_Null_Not_Allowed,               -- 09
912
913      CE_Overflow_Check_Failed,          -- 10
914      CE_Partition_Check_Failed,         -- 11
915      CE_Range_Check_Failed,             -- 12
916      CE_Tag_Check_Failed,               -- 13
917      PE_Access_Before_Elaboration,      -- 14
918      PE_Accessibility_Check_Failed,     -- 15
919      PE_Address_Of_Intrinsic,           -- 16
920      PE_Aliased_Parameters,             -- 17
921      PE_All_Guards_Closed,              -- 18
922      PE_Bad_Predicated_Generic_Type,    -- 19
923
924      PE_Current_Task_In_Entry_Body,     -- 20
925      PE_Duplicated_Entry_Address,       -- 21
926      PE_Explicit_Raise,                 -- 22
927      PE_Finalize_Raised_Exception,      -- 23
928      PE_Implicit_Return,                -- 24
929      PE_Misaligned_Address_Value,       -- 25
930      PE_Missing_Return,                 -- 26
931      PE_Overlaid_Controlled_Object,     -- 27
932      PE_Potentially_Blocking_Operation, -- 28
933      PE_Stubbed_Subprogram_Called,      -- 29
934
935      PE_Unchecked_Union_Restriction,    -- 30
936      PE_Non_Transportable_Actual,       -- 31
937      SE_Empty_Storage_Pool,             -- 32
938      SE_Explicit_Raise,                 -- 33
939      SE_Infinite_Recursion,             -- 34
940      SE_Object_Too_Large,               -- 35
941      PE_Stream_Operation_Not_Allowed,   -- 36
942      PE_Build_In_Place_Mismatch);       -- 37
943   pragma Convention (C, RT_Exception_Code);
944
945   Last_Reason_Code : constant :=
946     RT_Exception_Code'Pos (RT_Exception_Code'Last);
947   --  Last reason code
948
949   type Reason_Kind is (CE_Reason, PE_Reason, SE_Reason);
950   --  Categorization of reason codes by exception raised
951
952   Rkind : constant array (RT_Exception_Code range <>) of Reason_Kind :=
953             (CE_Access_Check_Failed            => CE_Reason,
954              CE_Access_Parameter_Is_Null       => CE_Reason,
955              CE_Discriminant_Check_Failed      => CE_Reason,
956              CE_Divide_By_Zero                 => CE_Reason,
957              CE_Explicit_Raise                 => CE_Reason,
958              CE_Index_Check_Failed             => CE_Reason,
959              CE_Invalid_Data                   => CE_Reason,
960              CE_Length_Check_Failed            => CE_Reason,
961              CE_Null_Exception_Id              => CE_Reason,
962              CE_Null_Not_Allowed               => CE_Reason,
963              CE_Overflow_Check_Failed          => CE_Reason,
964              CE_Partition_Check_Failed         => CE_Reason,
965              CE_Range_Check_Failed             => CE_Reason,
966              CE_Tag_Check_Failed               => CE_Reason,
967
968              PE_Access_Before_Elaboration      => PE_Reason,
969              PE_Accessibility_Check_Failed     => PE_Reason,
970              PE_Address_Of_Intrinsic           => PE_Reason,
971              PE_Aliased_Parameters             => PE_Reason,
972              PE_All_Guards_Closed              => PE_Reason,
973              PE_Bad_Predicated_Generic_Type    => PE_Reason,
974              PE_Current_Task_In_Entry_Body     => PE_Reason,
975              PE_Duplicated_Entry_Address       => PE_Reason,
976              PE_Explicit_Raise                 => PE_Reason,
977              PE_Finalize_Raised_Exception      => PE_Reason,
978              PE_Implicit_Return                => PE_Reason,
979              PE_Misaligned_Address_Value       => PE_Reason,
980              PE_Missing_Return                 => PE_Reason,
981              PE_Overlaid_Controlled_Object     => PE_Reason,
982              PE_Potentially_Blocking_Operation => PE_Reason,
983              PE_Stubbed_Subprogram_Called      => PE_Reason,
984              PE_Unchecked_Union_Restriction    => PE_Reason,
985              PE_Non_Transportable_Actual       => PE_Reason,
986              PE_Stream_Operation_Not_Allowed   => PE_Reason,
987              PE_Build_In_Place_Mismatch        => PE_Reason,
988
989              SE_Empty_Storage_Pool             => SE_Reason,
990              SE_Explicit_Raise                 => SE_Reason,
991              SE_Infinite_Recursion             => SE_Reason,
992              SE_Object_Too_Large               => SE_Reason);
993
994   --  Types for field offsets/sizes used in Seinfo, Sinfo.Nodes and
995   --  Einfo.Entities:
996
997   type Field_Offset is new Nat;
998   --  Offset of a node field, in units of the size of the field, which is
999   --  always a power of 2.
1000
1001   subtype Node_Offset is Field_Offset'Base range 1 .. Field_Offset'Base'Last;
1002
1003   subtype Slot_Count is Field_Offset;
1004   --  Count of number of slots. Same type as Field_Offset to avoid
1005   --  proliferation of type conversions.
1006
1007   subtype Field_Size_In_Bits is Field_Offset with Predicate =>
1008     Field_Size_In_Bits in 1 | 2 | 4 | 8 | 32;
1009
1010   subtype Opt_Field_Offset is Field_Offset'Base range -1 .. Field_Offset'Last;
1011   No_Field_Offset : constant Opt_Field_Offset := Opt_Field_Offset'First;
1012
1013   type Offset_Array_Index is new Nat;
1014   type Offset_Array is
1015     array (Offset_Array_Index range <>) of Opt_Field_Offset;
1016
1017end Types;
1018