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1 706 jeremybenn
------------------------------------------------------------------------------
2
--                                                                          --
3
--                         GNAT COMPILER COMPONENTS                         --
4
--                                                                          --
5
--                             S E M _ A T T R                              --
6
--                                                                          --
7
--                                 S p e c                                  --
8
--                                                                          --
9
--          Copyright (C) 1992-2011, 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
-- You should have received a copy of the GNU General Public License along  --
19
-- with this program; see file COPYING3.  If not see                        --
20
-- <http://www.gnu.org/licenses/>.                                          --
21
--                                                                          --
22
-- GNAT was originally developed  by the GNAT team at  New York University. --
23
-- Extensive contributions were provided by Ada Core Technologies Inc.      --
24
--                                                                          --
25
------------------------------------------------------------------------------
26
 
27
--  Attribute handling is isolated in a separate package to ease the addition
28
--  of implementation defined attributes. Logically this processing belongs
29
--  in chapter 4. See Sem_Ch4 for a description of the relation of the
30
--  Analyze and Resolve routines for expression components.
31
 
32
--  This spec also documents all GNAT implementation defined pragmas
33
 
34
with Exp_Tss; use Exp_Tss;
35
with Namet;   use Namet;
36
with Snames;  use Snames;
37
with Types;   use Types;
38
 
39
package Sem_Attr is
40
 
41
   -----------------------------------------
42
   -- Implementation Dependent Attributes --
43
   -----------------------------------------
44
 
45
   --  This section describes the implementation dependent attributes
46
   --  provided in GNAT, as well as constructing an array of flags
47
   --  indicating which attributes these are.
48
 
49
   Attribute_Impl_Def : Attribute_Class_Array := Attribute_Class_Array'(
50
 
51
      ------------------
52
      -- Abort_Signal --
53
      ------------------
54
 
55
      Attribute_Abort_Signal => True,
56
      --  Standard'Abort_Signal (Standard is the only allowed prefix) provides
57
      --  the entity for the special exception used to signal task abort or
58
      --  asynchronous transfer of control. Normally this attribute should only
59
      --  be used in the tasking runtime (it is highly peculiar, and completely
60
      --  outside the normal semantics of Ada, for a user program to intercept
61
      --  the abort exception).
62
 
63
      ------------------
64
      -- Address_Size --
65
      ------------------
66
 
67
      Attribute_Address_Size => True,
68
      --  Standard'Address_Size (Standard is the only allowed prefix) is
69
      --  a static constant giving the number of bits in an Address. It
70
      --  is used primarily for constructing the definition of Memory_Size
71
      --  in package Standard, but may be freely used in user programs.
72
      --  This is a static attribute.
73
 
74
      ---------------
75
      -- Asm_Input --
76
      ---------------
77
 
78
      Attribute_Asm_Input => True,
79
      --  Used only in conjunction with the Asm subprograms in package
80
      --  Machine_Code to construct machine instructions. See documentation
81
      --  in package Machine_Code in file s-maccod.ads.
82
 
83
      ----------------
84
      -- Asm_Output --
85
      ----------------
86
 
87
      Attribute_Asm_Output => True,
88
      --  Used only in conjunction with the Asm subprograms in package
89
      --  Machine_Code to construct machine instructions. See documentation
90
      --  in package Machine_Code in file s-maccod.ads.
91
 
92
      ---------------
93
      -- AST_Entry --
94
      ---------------
95
 
96
      Attribute_AST_Entry => True,
97
      --  E'Ast_Entry, where E is a task entry, yields a value of the
98
      --  predefined type System.DEC.AST_Handler, that enables the given
99
      --  entry to be called when an AST occurs. If the name to which the
100
      --  attribute applies has not been specified with the pragma AST_Entry,
101
      --  the attribute returns the value No_Ast_Handler, and no AST occurs.
102
      --  If the entry is for a task that is not callable (T'Callable False),
103
      --  the exception program error is raised. If an AST occurs for an
104
      --  entry of a task that is terminated, the program is erroneous.
105
      --
106
      --  The attribute AST_Entry is supported only in OpenVMS versions
107
      --  of GNAT. It will be rejected as illegal in other GNAT versions.
108
 
109
      ---------
110
      -- Bit --
111
      ---------
112
 
113
      Attribute_Bit => True,
114
      --  Obj'Bit, where Obj is any object, yields the bit offset within the
115
      --  storage unit (byte) that contains the first bit of storage allocated
116
      --  for the object. The attribute value is of type Universal_Integer,
117
      --  and is always a non-negative number not exceeding the value of
118
      --  System.Storage_Unit.
119
      --
120
      --  For an object that is a variable or a constant allocated in a
121
      --  register, the value is zero. (The use of this attribute does not
122
      --  force the allocation of a variable to memory).
123
      --
124
      --  For an object that is a formal parameter, this attribute applies to
125
      --  either the matching actual parameter or to a copy of the matching
126
      --  actual parameter.
127
      --
128
      --  For an access object the value is zero. Note that Obj.all'Bit is
129
      --  subject to an Access_Check for the designated object. Similarly
130
      --  for a record component X.C'Bit is subject to a discriminant check
131
      --  and X(I).Bit and X(I1..I2)'Bit are subject to index checks.
132
      --
133
      --  This attribute is designed to be compatible with the DEC Ada
134
      --  definition and implementation of the Bit attribute.
135
 
136
      ------------------
137
      -- Code_Address --
138
      ------------------
139
 
140
      Attribute_Code_Address => True,
141
      --  The reference subp'Code_Address, where subp is a subprogram entity,
142
      --  gives the address of the first generated instruction for the sub-
143
      --  program. This is often, but not always the same as the 'Address
144
      --  value, which is the address to be used in a call. The differences
145
      --  occur in the case of a nested procedure (where Address yields the
146
      --  address of the trampoline code used to load the static link), and on
147
      --  some systems which use procedure descriptors (in which case Address
148
      --  yields the address of the descriptor).
149
 
150
      -----------------------
151
      -- Default_Bit_Order --
152
      -----------------------
153
 
154
      Attribute_Default_Bit_Order => True,
155
      --  Standard'Default_Bit_Order (Standard is the only permissible prefix),
156
      --  provides the value System.Default_Bit_Order as a Pos value (0 for
157
      --  High_Order_First, 1 for Low_Order_First). This is used to construct
158
      --  the definition of Default_Bit_Order in package System. This is a
159
      --  static attribute.
160
 
161
      ---------------
162
      -- Elab_Body --
163
      ---------------
164
 
165
      Attribute_Elab_Body => True,
166
      --  This attribute can only be applied to a program unit name. It returns
167
      --  the entity for the corresponding elaboration procedure for elabor-
168
      --  ating the body of the referenced unit. This is used in the main
169
      --  generated elaboration procedure by the binder, and is not normally
170
      --  used in any other context, but there may be specialized situations in
171
      --  which it is useful to be able to call this elaboration procedure from
172
      --  Ada code, e.g. if it is necessary to do selective reelaboration to
173
      --  fix some error.
174
 
175
      --------------------
176
      -- Elab_Subp_Body --
177
      --------------------
178
 
179
      Attribute_Elab_Subp_Body => True,
180
      --  This attribute can only be applied to a library level subprogram
181
      --  name and is only relevant in CodePeer mode. It returns the entity
182
      --  for the corresponding elaboration procedure for elaborating the body
183
      --  of the referenced subprogram unit. This is used in the main generated
184
      --  elaboration procedure by the binder in CodePeer mode only.
185
 
186
      ---------------
187
      -- Elab_Spec --
188
      ---------------
189
 
190
      Attribute_Elab_Spec => True,
191
      --  This attribute can only be applied to a program unit name. It
192
      --  returns the entity for the corresponding elaboration procedure
193
      --  for elaborating the spec of the referenced unit. This is used
194
      --  in the main generated elaboration procedure by the binder, and
195
      --  is not normally used in any other context, but there may be
196
      --  specialized situations in which it is useful to be able to
197
      --  call this elaboration procedure from Ada code, e.g. if it
198
      --  is necessary to do selective reelaboration to fix some error.
199
 
200
      ----------------
201
      -- Elaborated --
202
      ----------------
203
 
204
      Attribute_Elaborated => True,
205
      --  Lunit'Elaborated, where Lunit is a library unit, yields a boolean
206
      --  value indicating whether or not the body of the designated library
207
      --  unit has been elaborated yet.
208
 
209
      --------------
210
      -- Enum_Rep --
211
      --------------
212
 
213
      Attribute_Enum_Rep => True,
214
      --  For every enumeration subtype S, S'Enum_Rep denotes a function
215
      --  with the following specification:
216
      --
217
      --    function S'Enum_Rep (Arg : S'Base) return universal_integer;
218
      --
219
      --  The function returns the representation value for the given
220
      --  enumeration value. This will be equal to the 'Pos value in the
221
      --  absence of an enumeration representation clause. This is a static
222
      --  attribute (i.e. the result is static if the argument is static).
223
 
224
      --------------
225
      -- Enum_Val --
226
      --------------
227
 
228
      Attribute_Enum_Val => True,
229
      --  For every enumeration subtype S, S'Enum_Val denotes a function
230
      --  with the following specification:
231
      --
232
      --    function S'Enum_Val (Arg : universal_integer) return S'Base;
233
      --
234
      --  This function performs the inverse transformation to Enum_Rep. Given
235
      --  a representation value for the type, it returns the corresponding
236
      --  enumeration value. Constraint_Error is raised if no value of the
237
      --  enumeration type corresponds to the given integer value.
238
 
239
      -----------------
240
      -- Fixed_Value --
241
      -----------------
242
 
243
      Attribute_Fixed_Value => True,
244
      --  For every fixed-point type S, S'Fixed_Value denotes a function
245
      --  with the following specification:
246
      --
247
      --    function S'Fixed_Value (Arg : universal_integer) return S;
248
      --
249
      --  The value returned is the fixed-point value V such that
250
      --
251
      --    V = Arg * S'Small
252
      --
253
      --  The effect is thus equivalent to first converting the argument to
254
      --  the integer type used to represent S, and then doing an unchecked
255
      --  conversion to the fixed-point type. This attribute is primarily
256
      --  intended for use in implementation of the input-output functions for
257
      --  fixed-point values.
258
 
259
      -----------------------
260
      -- Has_Discriminants --
261
      -----------------------
262
 
263
      Attribute_Has_Discriminants => True,
264
      --  Gtyp'Has_Discriminants, where Gtyp is a generic formal type, yields
265
      --  a Boolean value indicating whether or not the actual instantiation
266
      --  type has discriminants.
267
 
268
      ---------
269
      -- Img --
270
      ---------
271
 
272
      Attribute_Img => True,
273
      --  The 'Img function is defined for any prefix, P, that denotes an
274
      --  object of scalar type T. P'Img is equivalent to T'Image (P). This
275
      --  is convenient for debugging. For example:
276
      --
277
      --     Put_Line ("X = " & X'Img);
278
      --
279
      --  has the same meaning as the more verbose:
280
      --
281
      --     Put_Line ("X = " & Temperature_Type'Image (X));
282
      --
283
      --  where Temperature_Type is the subtype of the object X.
284
 
285
      -------------------
286
      -- Integer_Value --
287
      -------------------
288
 
289
      Attribute_Integer_Value => True,
290
      --  For every integer type S, S'Integer_Value denotes a function
291
      --  with the following specification:
292
      --
293
      --    function S'Integer_Value (Arg : universal_fixed) return S;
294
      --
295
      --  The value returned is the integer value V, such that
296
      --
297
      --    Arg = V * fixed-type'Small
298
      --
299
      --  The effect is thus equivalent to first doing an unchecked convert
300
      --  from the fixed-point type to its corresponding implementation type,
301
      --  and then converting the result to the target integer type. This
302
      --  attribute is primarily intended for use in implementation of the
303
      --  standard input-output functions for fixed-point values.
304
 
305
      Attribute_Invalid_Value => True,
306
      --  For every scalar type, S'Invalid_Value designates an undefined value
307
      --  of the type. If possible this value is an invalid value, and in fact
308
      --  is identical to the value that would be set if Initialize_Scalars
309
      --  mode were in effect (including the behavior of its value on
310
      --  environment variables or binder switches). The intended use is
311
      --  to set a value where initialization is required (e.g. as a result of
312
      --  the coding standards in use), but logically no initialization is
313
      --  needed, and the value should never be accessed.
314
 
315
      ------------------
316
      -- Machine_Size --
317
      ------------------
318
 
319
      Attribute_Machine_Size => True,
320
      --  This attribute is identical to the Object_Size attribute. It is
321
      --  provided for compatibility with the DEC attribute of this name.
322
 
323
      -----------------------
324
      -- Maximum_Alignment --
325
      -----------------------
326
 
327
      Attribute_Maximum_Alignment => True,
328
      --  Standard'Maximum_Alignment (Standard is the only permissible prefix)
329
      --  provides the maximum useful alignment value for the target. This
330
      --  is a static value that can be used to specify the alignment for an
331
      --  object, guaranteeing that it is properly aligned in all cases. The
332
      --  time this is useful is when an external object is imported and its
333
      --  alignment requirements are unknown. This is a static attribute.
334
 
335
      --------------------
336
      -- Mechanism_Code --
337
      --------------------
338
 
339
      Attribute_Mechanism_Code => True,
340
      --  function'Mechanism_Code yields an integer code for the mechanism
341
      --  used for the result of function, and subprogram'Mechanism_Code (n)
342
      --  yields the mechanism used for formal parameter number n (a static
343
      --  integer value, 1 = first parameter). The code returned is:
344
      --
345
      --     1 = by copy (value)
346
      --     2 = by reference
347
      --     3 = by descriptor (default descriptor type)
348
      --     4 = by descriptor (UBS  unaligned bit string)
349
      --     5 = by descriptor (UBSB aligned bit string with arbitrary bounds)
350
      --     6 = by descriptor (UBA  unaligned bit array)
351
      --     7 = by descriptor (S    string, also scalar access type parameter)
352
      --     8 = by descriptor (SB   string with arbitrary bounds)
353
      --     9 = by descriptor (A    contiguous array)
354
      --    10 = by descriptor (NCA  non-contiguous array)
355
 
356
      --------------------
357
      -- Null_Parameter --
358
      --------------------
359
 
360
      Attribute_Null_Parameter => True,
361
      --  A reference T'Null_Parameter denotes an (imaginary) object of type or
362
      --  subtype T allocated at (machine) address zero. The attribute is
363
      --  allowed only as the default expression of a formal parameter, or as
364
      --  an actual expression of a subprogram call. In either case, the
365
      --  subprogram must be imported.
366
      --
367
      --  The identity of the object is represented by the address zero in the
368
      --  argument list, independent of the passing mechanism (explicit or
369
      --  default).
370
      --
371
      --  The reason that this capability is needed is that for a record or
372
      --  other composite object passed by reference, there is no other way of
373
      --  specifying that a zero address should be passed.
374
 
375
      -----------------
376
      -- Object_Size --
377
      -----------------
378
 
379
      Attribute_Object_Size => True,
380
      --  Type'Object_Size is the same as Type'Size for all types except
381
      --  fixed-point types and discrete types. For fixed-point types and
382
      --  discrete types, this attribute gives the size used for default
383
      --  allocation of objects and components of the size. See section in
384
      --  Einfo ("Handling of type'Size values") for further details.
385
 
386
      -------------------------
387
      -- Passed_By_Reference --
388
      -------------------------
389
 
390
      Attribute_Passed_By_Reference => True,
391
      --  T'Passed_By_Reference for any subtype T returns a boolean value that
392
      --  is true if the type is normally passed by reference and false if the
393
      --  type is normally passed by copy in calls. For scalar types, the
394
      --  result is always False and is static. For non-scalar types, the
395
      --  result is non-static (since it is computed by Gigi).
396
 
397
      ------------------
398
      -- Range_Length --
399
      ------------------
400
 
401
      Attribute_Range_Length => True,
402
      --  T'Range_Length for any discrete type T yields the number of values
403
      --  represented by the subtype (zero for a null range). The result is
404
      --  static for static subtypes. Note that Range_Length applied to the
405
      --  index subtype of a one dimensional array always gives the same result
406
      --  as Range applied to the array itself. The result is of type universal
407
      --  integer.
408
 
409
      ---------
410
      -- Ref --
411
      ---------
412
 
413
      Attribute_Ref => True,
414
      --  System.Address'Ref (Address is the only permissible prefix) is
415
      --  equivalent to System'To_Address, provided for compatibility with
416
      --  other compilers.
417
 
418
      ------------------
419
      -- Storage_Unit --
420
      ------------------
421
 
422
      Attribute_Storage_Unit => True,
423
      --  Standard'Storage_Unit (Standard is the only permissible prefix)
424
      --  provides the value System.Storage_Unit, and is intended primarily
425
      --  for constructing this definition in package System (see note above
426
      --  in Default_Bit_Order description). The is a static attribute.
427
 
428
      ---------------
429
      -- Stub_Type --
430
      ---------------
431
 
432
      Attribute_Stub_Type => True,
433
      --  The GNAT implementation of remote access-to-classwide types is
434
      --  organised as described in AARM E.4(20.t): a value of an RACW type
435
      --  (designating a remote object) is represented as a normal access
436
      --  value, pointing to a "stub" object which in turn contains the
437
      --  necessary information to contact the designated remote object. A
438
      --  call on any dispatching operation of such a stub object does the
439
      --  remote call, if necessary, using the information in the stub object
440
      --  to locate the target partition, etc.
441
      --
442
      --  For a prefix T that denotes a remote access-to-classwide type,
443
      --  T'Stub_Type denotes the type of the corresponding stub objects.
444
      --
445
      --  By construction, the layout of T'Stub_Type is identical to that of
446
      --  System.Partition_Interface.RACW_Stub_Type (see implementation notes
447
      --  in body of Exp_Dist).
448
 
449
      -----------------
450
      -- Target_Name --
451
      -----------------
452
 
453
      Attribute_Target_Name => True,
454
      --  Standard'Target_Name yields the string identifying the target for the
455
      --  compilation, taken from Sdefault.Target_Name.
456
 
457
      ----------------
458
      -- To_Address --
459
      ----------------
460
 
461
      Attribute_To_Address => True,
462
      --  System'To_Address (System is the only permissible prefix) is a
463
      --  function that takes any integer value, and converts it into an
464
      --  address value. The semantics is to first convert the integer value to
465
      --  type Integer_Address according to normal conversion rules, and then
466
      --  to convert this to an address using the same semantics as the
467
      --  System.Storage_Elements.To_Address function. The important difference
468
      --  is that this is a static attribute so it can be used in
469
      --  initializations in preelaborate packages.
470
 
471
      ----------------
472
      -- Type_Class --
473
      ----------------
474
 
475
      Attribute_Type_Class => True,
476
      --  T'Type_Class for any type or subtype T yields the value of the type
477
      --  class for the full type of T. If T is a generic formal type, then the
478
      --  value is the value for the corresponding actual subtype. The value of
479
      --  this attribute is of type System.Aux_DEC.Type_Class, which has the
480
      --  following definition:
481
      --
482
      --    type Type_Class is
483
      --      (Type_Class_Enumeration,
484
      --       Type_Class_Integer,
485
      --       Type_Class_Fixed_Point,
486
      --       Type_Class_Floating_Point,
487
      --       Type_Class_Array,
488
      --       Type_Class_Record,
489
      --       Type_Class_Access,
490
      --       Type_Class_Task,
491
      --       Type_Class_Address);
492
      --
493
      --  Protected types yield the value Type_Class_Task, which thus applies
494
      --  to all concurrent types. This attribute is designed to be compatible
495
      --  with the DEC Ada attribute of the same name.
496
      --
497
      --  Note: if pragma Extend_System is used to merge the definitions of
498
      --  Aux_DEC into System, then the type Type_Class can be referenced
499
      --  as an entity within System, as can its enumeration literals.
500
 
501
      -----------------
502
      -- UET_Address --
503
      -----------------
504
 
505
      Attribute_UET_Address => True,
506
      --  Unit'UET_Address, where Unit is a program unit, yields the address
507
      --  of the unit exception table for the specified unit. This is only
508
      --  used in the internal implementation of exception handling. See the
509
      --  implementation of unit Ada.Exceptions for details on its use.
510
 
511
      ------------------------------
512
      -- Universal_Literal_String --
513
      ------------------------------
514
 
515
      Attribute_Universal_Literal_String => True,
516
      --  The prefix of 'Universal_Literal_String must be a named number.
517
      --  The static result is the string consisting of the characters of
518
      --  the number as defined in the original source. This allows the
519
      --  user program to access the actual text of named numbers without
520
      --  intermediate conversions and without the need to enclose the
521
      --  strings in quotes (which would preclude their use as numbers).
522
 
523
      -------------------------
524
      -- Unrestricted_Access --
525
      -------------------------
526
 
527
      Attribute_Unrestricted_Access => True,
528
      --  The Unrestricted_Access attribute is similar to Access except that
529
      --  all accessibility and aliased view checks are omitted. This is very
530
      --  much a user-beware attribute. Basically its status is very similar
531
      --  to Address, for which it is a desirable replacement where the value
532
      --  desired is an access type. In other words, its effect is identical
533
      --  to first taking 'Address and then doing an unchecked conversion to
534
      --  a desired access type. Note that in GNAT, but not necessarily in
535
      --  other implementations, the use of static chains for inner level
536
      --  subprograms means that Unrestricted_Access applied to a subprogram
537
      --  yields a value that can be called as long as the subprogram is in
538
      --  scope (normal Ada 95 accessibility rules restrict this usage).
539
 
540
      ---------------
541
      -- VADS_Size --
542
      ---------------
543
 
544
      Attribute_VADS_Size => True,
545
      --  Typ'VADS_Size yields the Size value typically yielded by some Ada 83
546
      --  compilers. The differences between VADS_Size and Size is that for
547
      --  scalar types for which no Size has been specified, VADS_Size yields
548
      --  the Object_Size rather than the Value_Size. For example, while
549
      --  Natural'Size is typically 31, the value of Natural'VADS_Size is 32.
550
      --  For all other types, Size and VADS_Size yield the same value.
551
 
552
      ----------------
553
      -- Value_Size --
554
      ----------------
555
 
556
      Attribute_Value_Size => True,
557
      --  Type'Value_Size is the number of bits required to represent value of
558
      --  the given subtype. It is the same as Type'Size, but, unlike Size, may
559
      --  be set for non-first subtypes. See section in Einfo ("Handling of
560
      --  type'Size values") for further details.
561
 
562
      ---------------
563
      -- Word_Size --
564
      ---------------
565
 
566
      Attribute_Word_Size => True,
567
      --  Standard'Word_Size (Standard is the only permissible prefix)
568
      --  provides the value System.Word_Size, and is intended primarily
569
      --  for constructing this definition in package System (see note above
570
      --  in Default_Bit_Order description). This is a static attribute.
571
 
572
      others => False);
573
 
574
   -----------------
575
   -- Subprograms --
576
   -----------------
577
 
578
   procedure Analyze_Attribute (N : Node_Id);
579
   --  Performs bottom up semantic analysis of an attribute. Note that the
580
   --  parser has already checked that type returning attributes appear only
581
   --  in appropriate contexts (i.e. in subtype marks, or as prefixes for
582
   --  other attributes).
583
 
584
   function Name_Implies_Lvalue_Prefix (Nam : Name_Id) return Boolean;
585
   --  Determine whether the name of an attribute reference categorizes its
586
   --  prefix as an lvalue. The following attributes fall under this bracket
587
   --  by directly or indirectly modifying their prefixes.
588
   --     Access
589
   --     Address
590
   --     Input
591
   --     Read
592
   --     Unchecked_Access
593
   --     Unrestricted_Access
594
 
595
   procedure Resolve_Attribute (N : Node_Id; Typ : Entity_Id);
596
   --  Performs type resolution of attribute. If the attribute yields a
597
   --  universal value, mark its type as that of the context. On the other
598
   --  hand, if the context itself is universal (as in T'Val (T'Pos (X)), mark
599
   --  the type as being the largest type of that class that can be used at
600
   --  run-time. This is correct since either the value gets folded (in which
601
   --  case it doesn't matter what type of the class we give if, since the
602
   --  folding uses universal arithmetic anyway) or it doesn't get folded (in
603
   --  which case it is going to be dealt with at runtime, and the largest type
604
   --  is right).
605
 
606
   function Stream_Attribute_Available
607
     (Typ          : Entity_Id;
608
      Nam          : TSS_Name_Type;
609
      Partial_View : Entity_Id := Empty) return Boolean;
610
   --  For a limited type Typ, return True if and only if the given attribute
611
   --  is available. For Ada 2005, availability is defined by 13.13.2(36/1).
612
   --  For Ada 95, an attribute is considered to be available if it has been
613
   --  specified using an attribute definition clause for the type, or for its
614
   --  full view, or for an ancestor of either. Parameter Partial_View is used
615
   --  only internally, when checking for an attribute definition clause that
616
   --  is not visible (Ada 95 only).
617
 
618
end Sem_Attr;

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