1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ A T T R -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2015, 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 34with Exp_Tss; use Exp_Tss; 35with Namet; use Namet; 36with Snames; use Snames; 37with Types; use Types; 38 39package Sem_Attr is 40 41 ----------------------------------------- 42 -- Implementation Dependent Attributes -- 43 ----------------------------------------- 44 45 -- This section describes the implementation dependent attributes provided 46 -- in GNAT, as well as constructing an array of flags indicating which 47 -- attributes these are. 48 49 Attribute_Impl_Def : constant Attribute_Class_Array := 50 Attribute_Class_Array'( 51 52 ------------------ 53 -- Abort_Signal -- 54 ------------------ 55 56 Attribute_Abort_Signal => True, 57 -- Standard'Abort_Signal (Standard is the only allowed prefix) provides 58 -- the entity for the special exception used to signal task abort or 59 -- asynchronous transfer of control. Normally this attribute should only 60 -- be used in the tasking runtime (it is highly peculiar, and completely 61 -- outside the normal semantics of Ada, for a user program to intercept 62 -- the abort exception). 63 64 ------------------ 65 -- Address_Size -- 66 ------------------ 67 68 Attribute_Address_Size => True, 69 -- Standard'Address_Size (Standard is the only allowed prefix) is 70 -- a static constant giving the number of bits in an Address. It 71 -- is used primarily for constructing the definition of Memory_Size 72 -- in package Standard, but may be freely used in user programs. 73 -- This is a static attribute. 74 75 --------------- 76 -- Asm_Input -- 77 --------------- 78 79 Attribute_Asm_Input => True, 80 -- Used only in conjunction with the Asm subprograms in package 81 -- Machine_Code to construct machine instructions. See documentation 82 -- in package Machine_Code in file s-maccod.ads. 83 84 ---------------- 85 -- Asm_Output -- 86 ---------------- 87 88 Attribute_Asm_Output => True, 89 -- Used only in conjunction with the Asm subprograms in package 90 -- Machine_Code to construct machine instructions. See documentation 91 -- in package Machine_Code in file s-maccod.ads. 92 93 --------- 94 -- Bit -- 95 --------- 96 97 Attribute_Bit => True, 98 -- Obj'Bit, where Obj is any object, yields the bit offset within the 99 -- storage unit (byte) that contains the first bit of storage allocated 100 -- for the object. The attribute value is of type Universal_Integer, 101 -- and is always a non-negative number not exceeding the value of 102 -- System.Storage_Unit. 103 -- 104 -- For an object that is a variable or a constant allocated in a 105 -- register, the value is zero. (The use of this attribute does not 106 -- force the allocation of a variable to memory). 107 -- 108 -- For an object that is a formal parameter, this attribute applies to 109 -- either the matching actual parameter or to a copy of the matching 110 -- actual parameter. 111 -- 112 -- For an access object the value is zero. Note that Obj.all'Bit is 113 -- subject to an Access_Check for the designated object. Similarly 114 -- for a record component X.C'Bit is subject to a discriminant check 115 -- and X(I).Bit and X(I1..I2)'Bit are subject to index checks. 116 -- 117 -- This attribute is designed to be compatible with the DEC Ada 118 -- definition and implementation of the Bit attribute. 119 120 ------------------ 121 -- Code_Address -- 122 ------------------ 123 124 Attribute_Code_Address => True, 125 -- The reference subp'Code_Address, where subp is a subprogram entity, 126 -- gives the address of the first generated instruction for the sub- 127 -- program. This is often, but not always the same as the 'Address 128 -- value, which is the address to be used in a call. The differences 129 -- occur in the case of a nested procedure (where Address yields the 130 -- address of the trampoline code used to load the static link), and on 131 -- some systems which use procedure descriptors (in which case Address 132 -- yields the address of the descriptor). 133 134 ----------------------- 135 -- Default_Bit_Order -- 136 ----------------------- 137 138 Attribute_Default_Bit_Order => True, 139 -- Standard'Default_Bit_Order (Standard is the only permissible prefix) 140 -- provides the value System.Default_Bit_Order as a Pos value (0 for 141 -- High_Order_First, 1 for Low_Order_First). This is used to construct 142 -- the definition of Default_Bit_Order in package System. This is a 143 -- static attribute. 144 145 ---------------------------------- 146 -- Default_Scalar_Storage_Order -- 147 ---------------------------------- 148 149 Attribute_Default_Scalar_Storage_Order => True, 150 -- Standard'Default_Scalar_Storage_Order (Standard is the 151 -- only permissible prefix) provides the current value of the 152 -- default scalar storage order (as specified using pragma 153 -- Default_Scalar_Storage_Order, or equal to Default_Bit_Order if 154 -- unspecified) as a System.Bit_Order value. This is a static attribute. 155 156 ----------- 157 -- Deref -- 158 ----------- 159 160 Attribute_Deref => True, 161 -- typ'Deref (expr) is valid only if expr is of type System'Address. 162 -- The result is an object of type typ that is obtained by treating the 163 -- address as an access-to-typ value that points to the result. It is 164 -- basically equivalent to (atyp!expr).all where atyp is an access type 165 -- for the type. 166 167 --------------- 168 -- Elab_Body -- 169 --------------- 170 171 Attribute_Elab_Body => True, 172 -- This attribute can only be applied to a program unit name. It 173 -- returns the entity for the corresponding elaboration procedure for 174 -- elaborating the body of the referenced unit. This is used in the main 175 -- generated elaboration procedure by the binder, and is not normally 176 -- used in any other context, but there may be specialized situations in 177 -- which it is useful to be able to call this elaboration procedure from 178 -- Ada code, e.g. if it is necessary to do selective reelaboration to 179 -- fix some error. 180 181 -------------------- 182 -- Elab_Subp_Body -- 183 -------------------- 184 185 Attribute_Elab_Subp_Body => True, 186 -- This attribute can only be applied to a library level subprogram 187 -- name and is only relevant in CodePeer mode. It returns the entity 188 -- for the corresponding elaboration procedure for elaborating the body 189 -- of the referenced subprogram unit. This is used in the main generated 190 -- elaboration procedure by the binder in CodePeer mode only. 191 192 --------------- 193 -- Elab_Spec -- 194 --------------- 195 196 Attribute_Elab_Spec => True, 197 -- This attribute can only be applied to a program unit name. It 198 -- returns the entity for the corresponding elaboration procedure for 199 -- elaborating the spec of the referenced unit. This is used in the main 200 -- generated elaboration procedure by the binder, and is not normally 201 -- used in any other context, but there may be specialized situations in 202 -- which it is useful to be able to call this elaboration procedure from 203 -- Ada code, e.g. if it is necessary to do selective reelaboration to 204 -- fix some error. 205 206 ---------------- 207 -- Elaborated -- 208 ---------------- 209 210 Attribute_Elaborated => True, 211 -- Lunit'Elaborated, where Lunit is a library unit, yields a boolean 212 -- value indicating whether or not the body of the designated library 213 -- unit has been elaborated yet. 214 215 -------------- 216 -- Enum_Rep -- 217 -------------- 218 219 Attribute_Enum_Rep => True, 220 -- For every enumeration subtype S, S'Enum_Rep denotes a function 221 -- with the following specification: 222 -- 223 -- function S'Enum_Rep (Arg : S'Base) return universal_integer; 224 -- 225 -- The function returns the representation value for the given 226 -- enumeration value. This will be equal to the 'Pos value in the 227 -- absence of an enumeration representation clause. This is a static 228 -- attribute (i.e. the result is static if the argument is static). 229 230 -------------- 231 -- Enum_Val -- 232 -------------- 233 234 Attribute_Enum_Val => True, 235 -- For every enumeration subtype S, S'Enum_Val denotes a function with 236 -- the following specification: 237 -- 238 -- function S'Enum_Val (Arg : universal_integer) return S'Base; 239 -- 240 -- This function performs the inverse transformation to Enum_Rep. Given 241 -- a representation value for the type, it returns the corresponding 242 -- enumeration value. Constraint_Error is raised if no value of the 243 -- enumeration type corresponds to the given integer value. 244 245 ----------------- 246 -- Fixed_Value -- 247 ----------------- 248 249 Attribute_Fixed_Value => True, 250 -- For every fixed-point type S, S'Fixed_Value denotes a function 251 -- with the following specification: 252 -- 253 -- function S'Fixed_Value (Arg : universal_integer) return S; 254 -- 255 -- The value returned is the fixed-point value V such that 256 -- 257 -- V = Arg * S'Small 258 -- 259 -- The effect is thus equivalent to first converting the argument to 260 -- the integer type used to represent S, and then doing an unchecked 261 -- conversion to the fixed-point type. This attribute is primarily 262 -- intended for use in implementation of the input-output functions 263 -- for fixed-point values. 264 265 ----------------------- 266 -- Has_Discriminants -- 267 ----------------------- 268 269 Attribute_Has_Discriminants => True, 270 -- Gtyp'Has_Discriminants, where Gtyp is a generic formal type, yields 271 -- a Boolean value indicating whether or not the actual instantiation 272 -- type has discriminants. 273 274 --------- 275 -- Img -- 276 --------- 277 278 Attribute_Img => True, 279 -- The 'Img function is defined for any prefix, P, that denotes an 280 -- object of scalar type T. P'Img is equivalent to T'Image (P). This 281 -- is convenient for debugging. For example: 282 -- 283 -- Put_Line ("X = " & X'Img); 284 -- 285 -- has the same meaning as the more verbose: 286 -- 287 -- Put_Line ("X = " & Temperature_Type'Image (X)); 288 -- 289 -- where Temperature_Type is the subtype of the object X. 290 291 ------------------- 292 -- Integer_Value -- 293 ------------------- 294 295 Attribute_Integer_Value => True, 296 -- For every integer type S, S'Integer_Value denotes a function 297 -- with the following specification: 298 -- 299 -- function S'Integer_Value (Arg : universal_fixed) return S; 300 -- 301 -- The value returned is the integer value V, such that 302 -- 303 -- Arg = V * fixed-type'Small 304 -- 305 -- The effect is thus equivalent to first doing an unchecked convert 306 -- from the fixed-point type to its corresponding implementation type, 307 -- and then converting the result to the target integer type. This 308 -- attribute is primarily intended for use in implementation of the 309 -- standard input-output functions for fixed-point values. 310 311 Attribute_Invalid_Value => True, 312 -- For every scalar type, S'Invalid_Value designates an undefined value 313 -- of the type. If possible this value is an invalid value, and in fact 314 -- is identical to the value that would be set if Initialize_Scalars 315 -- mode were in effect (including the behavior of its value on 316 -- environment variables or binder switches). The intended use is to 317 -- set a value where initialization is required (e.g. as a result of the 318 -- coding standards in use), but logically no initialization is needed, 319 -- and the value should never be accessed. 320 321 Attribute_Loop_Entry => True, 322 -- For every object of a non-limited type, S'Loop_Entry [(Loop_Name)] 323 -- denotes the constant value of prefix S at the point of entry into the 324 -- related loop. The type of the attribute is the type of the prefix. 325 326 ------------------ 327 -- Machine_Size -- 328 ------------------ 329 330 Attribute_Machine_Size => True, 331 -- This attribute is identical to the Object_Size attribute. It is 332 -- provided for compatibility with the DEC attribute of this name. 333 334 ----------------------- 335 -- Maximum_Alignment -- 336 ----------------------- 337 338 Attribute_Maximum_Alignment => True, 339 -- Standard'Maximum_Alignment (Standard is the only permissible prefix) 340 -- provides the maximum useful alignment value for the target. This is a 341 -- static value that can be used to specify the alignment for an object, 342 -- guaranteeing that it is properly aligned in all cases. The time this 343 -- is useful is when an external object is imported and its alignment 344 -- requirements are unknown. This is a static attribute. 345 346 -------------------- 347 -- Mechanism_Code -- 348 -------------------- 349 350 Attribute_Mechanism_Code => True, 351 -- function'Mechanism_Code yields an integer code for the mechanism 352 -- used for the result of function, and subprogram'Mechanism_Code (n) 353 -- yields the mechanism used for formal parameter number n (a static 354 -- integer value, 1 = first parameter). The code returned is: 355 -- 356 -- 1 = by copy (value) 357 -- 2 = by reference 358 -- 3 = by descriptor (default descriptor type) 359 -- 4 = by descriptor (UBS unaligned bit string) 360 -- 5 = by descriptor (UBSB aligned bit string with arbitrary bounds) 361 -- 6 = by descriptor (UBA unaligned bit array) 362 -- 7 = by descriptor (S string, also scalar access type parameter) 363 -- 8 = by descriptor (SB string with arbitrary bounds) 364 -- 9 = by descriptor (A contiguous array) 365 -- 10 = by descriptor (NCA non-contiguous array) 366 367 -------------------- 368 -- Null_Parameter -- 369 -------------------- 370 371 Attribute_Null_Parameter => True, 372 -- A reference T'Null_Parameter denotes an (imaginary) object of type 373 -- or subtype T allocated at (machine) address zero. The attribute is 374 -- allowed only as the default expression of a formal parameter, or 375 -- as an actual expression of a subprogram call. In either case, the 376 -- subprogram must be imported. 377 -- 378 -- The identity of the object is represented by the address zero in 379 -- the argument list, independent of the passing mechanism (explicit 380 -- or default). 381 -- 382 -- The reason that this capability is needed is that for a record or 383 -- other composite object passed by reference, there is no other way 384 -- of specifying that a zero address should be passed. 385 386 ----------------- 387 -- Object_Size -- 388 ----------------- 389 390 Attribute_Object_Size => True, 391 -- Type'Object_Size is the same as Type'Size for all types except 392 -- fixed-point types and discrete types. For fixed-point types and 393 -- discrete types, this attribute gives the size used for default 394 -- allocation of objects and components of the size. See section in 395 -- Einfo ("Handling of type'Size values") for further details. 396 397 ------------------------- 398 -- Passed_By_Reference -- 399 ------------------------- 400 401 Attribute_Passed_By_Reference => True, 402 -- T'Passed_By_Reference for any subtype T returns a boolean value that 403 -- is true if the type is normally passed by reference and false if the 404 -- type is normally passed by copy in calls. For scalar types, the 405 -- result is always False and is static. For non-scalar types, the 406 -- result is non-static (since it is computed by Gigi). 407 408 ------------------ 409 -- Range_Length -- 410 ------------------ 411 412 Attribute_Range_Length => True, 413 -- T'Range_Length for any discrete type T yields the number of values 414 -- represented by the subtype (zero for a null range). The result is 415 -- static for static subtypes. Note that Range_Length applied to the 416 -- index subtype of a one dimensional array always gives the same result 417 -- as Range applied to the array itself. The result is of type universal 418 -- integer. 419 420 --------- 421 -- Ref -- 422 --------- 423 424 Attribute_Ref => True, 425 -- System.Address'Ref (Address is the only permissible prefix) is 426 -- equivalent to System'To_Address, provided for compatibility with 427 -- other compilers. 428 429 ------------------ 430 -- Storage_Unit -- 431 ------------------ 432 433 Attribute_Storage_Unit => True, 434 -- Standard'Storage_Unit (Standard is the only permissible prefix) 435 -- provides the value System.Storage_Unit, and is intended primarily 436 -- for constructing this definition in package System (see note above 437 -- in Default_Bit_Order description). The is a static attribute. 438 439 --------------- 440 -- Stub_Type -- 441 --------------- 442 443 Attribute_Stub_Type => True, 444 -- The GNAT implementation of remote access-to-classwide types is 445 -- organised as described in AARM E.4(20.t): a value of an RACW type 446 -- (designating a remote object) is represented as a normal access 447 -- value, pointing to a "stub" object which in turn contains the 448 -- necessary information to contact the designated remote object. A 449 -- call on any dispatching operation of such a stub object does the 450 -- remote call, if necessary, using the information in the stub object 451 -- to locate the target partition, etc. 452 -- 453 -- For a prefix T that denotes a remote access-to-classwide type, 454 -- T'Stub_Type denotes the type of the corresponding stub objects. 455 -- 456 -- By construction, the layout of T'Stub_Type is identical to that of 457 -- System.Partition_Interface.RACW_Stub_Type (see implementation notes 458 -- in body of Exp_Dist). 459 460 ----------------- 461 -- Target_Name -- 462 ----------------- 463 464 Attribute_Target_Name => True, 465 -- Standard'Target_Name yields the string identifying the target for the 466 -- compilation, taken from Sdefault.Target_Name. 467 468 ---------------- 469 -- To_Address -- 470 ---------------- 471 472 Attribute_To_Address => True, 473 -- System'To_Address (System is the only permissible prefix) is a 474 -- function that takes any integer value, and converts it into an 475 -- address value. The semantics is to first convert the integer value to 476 -- type Integer_Address according to normal conversion rules, and then 477 -- to convert this to an address using the same semantics as the 478 -- System.Storage_Elements.To_Address function. The important difference 479 -- is that this is a static attribute so it can be used in 480 -- initializations in preelaborate packages. 481 482 ---------------- 483 -- Type_Class -- 484 ---------------- 485 486 Attribute_Type_Class => True, 487 -- T'Type_Class for any type or subtype T yields the value of the type 488 -- class for the full type of T. If T is a generic formal type, then the 489 -- value is the value for the corresponding actual subtype. The value of 490 -- this attribute is of type System.Aux_DEC.Type_Class, which has the 491 -- following definition: 492 -- 493 -- type Type_Class is 494 -- (Type_Class_Enumeration, 495 -- Type_Class_Integer, 496 -- Type_Class_Fixed_Point, 497 -- Type_Class_Floating_Point, 498 -- Type_Class_Array, 499 -- Type_Class_Record, 500 -- Type_Class_Access, 501 -- Type_Class_Task, 502 -- Type_Class_Address); 503 -- 504 -- Protected types yield the value Type_Class_Task, which thus applies 505 -- to all concurrent types. This attribute is designed to be compatible 506 -- with the DEC Ada attribute of the same name. 507 -- 508 -- Note: if pragma Extend_System is used to merge the definitions of 509 -- Aux_DEC into System, then the type Type_Class can be referenced 510 -- as an entity within System, as can its enumeration literals. 511 512 ------------------------------ 513 -- Universal_Literal_String -- 514 ------------------------------ 515 516 Attribute_Universal_Literal_String => True, 517 -- The prefix of 'Universal_Literal_String must be a named number. 518 -- The static result is the string consisting of the characters of 519 -- the number as defined in the original source. This allows the 520 -- user program to access the actual text of named numbers without 521 -- intermediate conversions and without the need to enclose the 522 -- strings in quotes (which would preclude their use as numbers). 523 524 ------------------------- 525 -- Unrestricted_Access -- 526 ------------------------- 527 528 Attribute_Unrestricted_Access => True, 529 -- The Unrestricted_Access attribute is similar to Access except that 530 -- all accessibility and aliased view checks are omitted. This is very 531 -- much a user-beware attribute. Basically its status is very similar 532 -- to Address, for which it is a desirable replacement where the value 533 -- desired is an access type. In other words, its effect is identical 534 -- to first taking 'Address and then doing an unchecked conversion to 535 -- a desired access type. Note that in GNAT, but not necessarily in 536 -- other implementations, the use of static chains for inner level 537 -- subprograms means that Unrestricted_Access applied to a subprogram 538 -- yields a value that can be called as long as the subprogram is in 539 -- scope (normal Ada 95 accessibility rules restrict this usage). 540 541 --------------- 542 -- VADS_Size -- 543 --------------- 544 545 Attribute_VADS_Size => True, 546 -- Typ'VADS_Size yields the Size value typically yielded by some Ada 83 547 -- compilers. The differences between VADS_Size and Size is that for 548 -- scalar types for which no Size has been specified, VADS_Size yields 549 -- the Object_Size rather than the Value_Size. For example, while 550 -- Natural'Size is typically 31, the value of Natural'VADS_Size is 32. 551 -- For all other types, Size and VADS_Size yield the same value. 552 553 ------------------- 554 -- Valid_Scalars -- 555 ------------------- 556 557 Attribute_Valid_Scalars => True, 558 -- Obj'Valid_Scalars can be applied to any object. The result depends 559 -- on the type of the object: 560 -- 561 -- For a scalar type, the result is the same as obj'Valid 562 -- 563 -- For an array object, the result is True if the result of applying 564 -- Valid_Scalars to every component is True. For an empty array the 565 -- result is True. 566 -- 567 -- For a record object, the result is True if the result of applying 568 -- Valid_Scalars to every component is True. For class-wide types, 569 -- only the components of the base type are checked. For variant 570 -- records, only the components actually present are checked. The 571 -- discriminants, if any, are also checked. If there are no components 572 -- or discriminants, the result is True. 573 -- 574 -- For any other type that has discriminants, the result is True if 575 -- the result of applying Valid_Scalars to each discriminant is True. 576 -- 577 -- For all other types, the result is always True 578 -- 579 -- A warning is given for a trivially True result, when the attribute 580 -- is applied to an object that is not of scalar, array, or record 581 -- type, or in the composite case if no scalar subcomponents exist. For 582 -- a variant record, the warning is given only if none of the variants 583 -- have scalar subcomponents. In addition, the warning is suppressed 584 -- for private types, or generic formal types in an instance. 585 586 ---------------- 587 -- Value_Size -- 588 ---------------- 589 590 Attribute_Value_Size => True, 591 -- Type'Value_Size is the number of bits required to represent value of 592 -- the given subtype. It is the same as Type'Size, but, unlike Size, may 593 -- be set for non-first subtypes. See section in Einfo ("Handling of 594 -- type'Size values") for further details. 595 596 --------------- 597 -- Word_Size -- 598 --------------- 599 600 Attribute_Word_Size => True, 601 -- Standard'Word_Size (Standard is the only permissible prefix) 602 -- provides the value System.Word_Size, and is intended primarily 603 -- for constructing this definition in package System (see note above 604 -- in Default_Bit_Order description). This is a static attribute. 605 606 others => False); 607 608 ----------------- 609 -- Subprograms -- 610 ----------------- 611 612 procedure Analyze_Attribute (N : Node_Id); 613 -- Performs bottom up semantic analysis of an attribute. Note that the 614 -- parser has already checked that type returning attributes appear only 615 -- in appropriate contexts (i.e. in subtype marks, or as prefixes for 616 -- other attributes). 617 618 function Name_Implies_Lvalue_Prefix (Nam : Name_Id) return Boolean; 619 -- Determine whether the name of an attribute reference categorizes its 620 -- prefix as an lvalue. The following attributes fall under this bracket 621 -- by directly or indirectly modifying their prefixes. 622 -- Access 623 -- Address 624 -- Input 625 -- Read 626 -- Unchecked_Access 627 -- Unrestricted_Access 628 629 procedure Resolve_Attribute (N : Node_Id; Typ : Entity_Id); 630 -- Performs type resolution of attribute. If the attribute yields a 631 -- universal value, mark its type as that of the context. On the other 632 -- hand, if the context itself is universal (as in T'Val (T'Pos (X)), mark 633 -- the type as being the largest type of that class that can be used at 634 -- run-time. This is correct since either the value gets folded (in which 635 -- case it doesn't matter what type of the class we give if, since the 636 -- folding uses universal arithmetic anyway) or it doesn't get folded (in 637 -- which case it is going to be dealt with at runtime, and the largest type 638 -- is right). 639 640 function Stream_Attribute_Available 641 (Typ : Entity_Id; 642 Nam : TSS_Name_Type; 643 Partial_View : Entity_Id := Empty) return Boolean; 644 -- For a limited type Typ, return True if and only if the given attribute 645 -- is available. For Ada 2005, availability is defined by 13.13.2(36/1). 646 -- For Ada 95, an attribute is considered to be available if it has been 647 -- specified using an attribute definition clause for the type, or for its 648 -- full view, or for an ancestor of either. Parameter Partial_View is used 649 -- only internally, when checking for an attribute definition clause that 650 -- is not visible (Ada 95 only). 651 652end Sem_Attr; 653