gcc/ada/aspects.ads

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  30 ------------------------------------------------------------------------------
  31
  32 --  This package defines the aspects that are recognized by GNAT in aspect
  33 --  specifications. It also contains the subprograms for storing/retrieving
  34 --  aspect specifications from the tree. The semantic processing for aspect
  35 --  specifications is found in Sem_Ch13.Analyze_Aspect_Specifications.
  36
  37 ------------------------
  38 -- Adding New Aspects --
  39 ------------------------
  40
  41 --  In general, each aspect should have a corresponding pragma, so that the
  42 --  newly developed functionality is available for Ada versions < Ada 2012.
  43 --  When both are defined, it is convenient to first transform the aspect into
  44 --  an equivalent pragma in Sem_Ch13.Analyze_Aspect_Specifications, and then
  45 --  analyze the pragma in Sem_Prag.Analyze_Pragma.
  46
  47 --  To add a new aspect, you need to do the following
  48
  49 --    1. Create a name in snames.ads-tmpl
  50
  51 --    2. Create a value in type Aspect_Id in this unit
  52
  53 --    3. Add a value for the aspect in the global arrays defined in this unit
  54
  55 --    4. Add code for the aspect in Sem_Ch13.Analyze_Aspect_Specifications.
  56 --       This may involve adding some nodes to the tree to perform additional
  57 --       treatments later.
  58
  59 --    5. If the semantic analysis of expressions/names in the aspect should not
  60 --       occur at the point the aspect is defined, add code in the adequate
  61 --       semantic analysis procedure for the aspect. For example, this is the
  62 --       case for aspects Pre and Post on subprograms, which are pre-analyzed
  63 --       at the end of the declaration list to which the subprogram belongs,
  64 --       and fully analyzed (possibly with expansion) during the semantic
  65 --       analysis of subprogram bodies.
  66
  67 with Namet;  use Namet;
  68 with Snames; use Snames;
  69 with Types;  use Types;
  70
  71 package Aspects is
  72
  73    --  Type defining recognized aspects
  74
  75    type Aspect_Id is
  76      (No_Aspect,                            -- Dummy entry for no aspect
  77       Aspect_Abstract_State,                -- GNAT
  78       Aspect_Address,
  79       Aspect_Alignment,
  80       Aspect_Attach_Handler,
  81       Aspect_Bit_Order,
  82       Aspect_Component_Size,
  83       Aspect_Constant_Indexing,
  84       Aspect_Contract_Case,                 -- GNAT
  85       Aspect_Contract_Cases,                -- GNAT
  86       Aspect_Convention,
  87       Aspect_CPU,
  88       Aspect_Default_Component_Value,
  89       Aspect_Default_Iterator,
  90       Aspect_Default_Value,
  91       Aspect_Dimension,                     -- GNAT
  92       Aspect_Dimension_System,              -- GNAT
  93       Aspect_Dispatching_Domain,
  94       Aspect_Dynamic_Predicate,
  95       Aspect_External_Name,
  96       Aspect_External_Tag,
  97       Aspect_Global,                        -- GNAT
  98       Aspect_Implicit_Dereference,
  99       Aspect_Input,
 100       Aspect_Interrupt_Priority,
 101       Aspect_Invariant,                     -- GNAT
 102       Aspect_Iterator_Element,
 103       Aspect_Link_Name,
 104       Aspect_Machine_Radix,
 105       Aspect_Object_Size,                   -- GNAT
 106       Aspect_Output,
 107       Aspect_Post,
 108       Aspect_Postcondition,
 109       Aspect_Pre,
 110       Aspect_Precondition,
 111       Aspect_Predicate,                     -- GNAT
 112       Aspect_Priority,
 113       Aspect_Read,
 114       Aspect_Relative_Deadline,
 115       Aspect_Scalar_Storage_Order,          -- GNAT
 116       Aspect_Simple_Storage_Pool,           -- GNAT
 117       Aspect_Size,
 118       Aspect_Small,
 119       Aspect_Static_Predicate,
 120       Aspect_Storage_Pool,
 121       Aspect_Storage_Size,
 122       Aspect_Stream_Size,
 123       Aspect_Suppress,
 124       Aspect_Synchronization,
 125       Aspect_Test_Case,                     -- GNAT
 126       Aspect_Type_Invariant,
 127       Aspect_Unsuppress,
 128       Aspect_Value_Size,                    -- GNAT
 129       Aspect_Variable_Indexing,
 130       Aspect_Warnings,                      -- GNAT
 131       Aspect_Write,
 132
 133       --  The following aspects correspond to library unit pragmas
 134
 135       Aspect_All_Calls_Remote,
 136       Aspect_Compiler_Unit,                 -- GNAT
 137       Aspect_Elaborate_Body,
 138       Aspect_Preelaborate,
 139       Aspect_Preelaborate_05,               -- GNAT
 140       Aspect_Pure,
 141       Aspect_Pure_05,                       -- GNAT
 142       Aspect_Pure_12,                       -- GNAT
 143       Aspect_Remote_Call_Interface,
 144       Aspect_Remote_Types,
 145       Aspect_Shared_Passive,
 146       Aspect_Universal_Data,                -- GNAT
 147
 148       --  Remaining aspects have a static boolean value that turns the aspect
 149       --  on or off. They all correspond to pragmas, but are only converted to
 150       --  the pragmas where the value is True. A value of False normally means
 151       --  that the aspect is ignored, except in the case of derived types where
 152       --  the aspect value is inherited from the parent, in which case, we do
 153       --  not allow False if we inherit a True value from the parent.
 154
 155       Aspect_Ada_2005,                      -- GNAT
 156       Aspect_Ada_2012,                      -- GNAT
 157       Aspect_Asynchronous,
 158       Aspect_Atomic,
 159       Aspect_Atomic_Components,
 160       Aspect_Discard_Names,
 161       Aspect_Export,
 162       Aspect_Favor_Top_Level,               -- GNAT
 163       Aspect_Independent,
 164       Aspect_Independent_Components,
 165       Aspect_Import,
 166       Aspect_Inline,
 167       Aspect_Inline_Always,                 -- GNAT
 168       Aspect_Interrupt_Handler,
 169       Aspect_No_Return,
 170       Aspect_Pack,
 171       Aspect_Persistent_BSS,                -- GNAT
 172       Aspect_Preelaborable_Initialization,
 173       Aspect_Pure_Function,                 -- GNAT
 174       Aspect_Remote_Access_Type,            -- GNAT
 175       Aspect_Shared,                        -- GNAT (equivalent to Atomic)
 176       Aspect_Simple_Storage_Pool_Type,      -- GNAT
 177       Aspect_Suppress_Debug_Info,           -- GNAT
 178       Aspect_Unchecked_Union,
 179       Aspect_Universal_Aliasing,            -- GNAT
 180       Aspect_Unmodified,                    -- GNAT
 181       Aspect_Unreferenced,                  -- GNAT
 182       Aspect_Unreferenced_Objects,          -- GNAT
 183       Aspect_Volatile,
 184       Aspect_Volatile_Components,
 185
 186       --  Aspects that have a static boolean value but don't correspond to
 187       --  pragmas
 188
 189       Aspect_Lock_Free);
 190
 191    subtype Aspect_Id_Exclude_No_Aspect is
 192      Aspect_Id range Aspect_Id'Succ (No_Aspect) .. Aspect_Id'Last;
 193    --  Aspect_Id's excluding No_Aspect
 194
 195    --  The following array indicates aspects that accept 'Class
 196
 197    Class_Aspect_OK : constant array (Aspect_Id) of Boolean :=
 198                        (Aspect_Invariant      => True,
 199                         Aspect_Pre            => True,
 200                         Aspect_Predicate      => True,
 201                         Aspect_Post           => True,
 202                         Aspect_Type_Invariant => True,
 203                         others                => False);
 204
 205    --  The following array indicates aspects that a subtype inherits from
 206    --  its base type. True means that the subtype inherits the aspect from
 207    --  its base type. False means it is not inherited.
 208
 209    Base_Aspect : constant array (Aspect_Id) of Boolean :=
 210                    (Aspect_Atomic                  => True,
 211                     Aspect_Atomic_Components       => True,
 212                     Aspect_Discard_Names           => True,
 213                     Aspect_Independent_Components  => True,
 214                     Aspect_Iterator_Element        => True,
 215                     Aspect_Constant_Indexing       => True,
 216                     Aspect_Default_Iterator        => True,
 217                     Aspect_Type_Invariant          => True,
 218                     Aspect_Unchecked_Union         => True,
 219                     Aspect_Variable_Indexing       => True,
 220                     Aspect_Volatile                => True,
 221                     others                         => False);
 222
 223    --  The following array identifies all implementation defined aspects
 224
 225    Impl_Defined_Aspects : constant array (Aspect_Id) of Boolean :=
 226                             (Aspect_Abstract_State           => True,
 227                              Aspect_Ada_2005                 => True,
 228                              Aspect_Ada_2012                 => True,
 229                              Aspect_Compiler_Unit            => True,
 230                              Aspect_Contract_Case            => True,
 231                              Aspect_Contract_Cases           => True,
 232                              Aspect_Dimension                => True,
 233                              Aspect_Dimension_System         => True,
 234                              Aspect_Favor_Top_Level          => True,
 235                              Aspect_Global                   => True,
 236                              Aspect_Inline_Always            => True,
 237                              Aspect_Invariant                => True,
 238                              Aspect_Lock_Free                => True,
 239                              Aspect_Object_Size              => True,
 240                              Aspect_Persistent_BSS           => True,
 241                              Aspect_Predicate                => True,
 242                              Aspect_Preelaborate_05          => True,
 243                              Aspect_Pure_05                  => True,
 244                              Aspect_Pure_12                  => True,
 245                              Aspect_Pure_Function            => True,
 246                              Aspect_Remote_Access_Type       => True,
 247                              Aspect_Scalar_Storage_Order     => True,
 248                              Aspect_Shared                   => True,
 249                              Aspect_Simple_Storage_Pool      => True,
 250                              Aspect_Simple_Storage_Pool_Type => True,
 251                              Aspect_Suppress_Debug_Info      => True,
 252                              Aspect_Test_Case                => True,
 253                              Aspect_Universal_Aliasing       => True,
 254                              Aspect_Universal_Data           => True,
 255                              Aspect_Unmodified               => True,
 256                              Aspect_Unreferenced             => True,
 257                              Aspect_Unreferenced_Objects     => True,
 258                              Aspect_Value_Size               => True,
 259                              Aspect_Warnings                 => True,
 260                              others                          => False);
 261
 262    --  The following array indicates aspects for which multiple occurrences of
 263    --  the same aspect attached to the same declaration are allowed.
 264
 265    No_Duplicates_Allowed : constant array (Aspect_Id) of Boolean :=
 266                              (Aspect_Contract_Case  => False,
 267                               Aspect_Test_Case      => False,
 268                               others                => True);
 269
 270    --  The following array indicates type aspects that are inherited and apply
 271    --  to the class-wide type as well.
 272
 273    Inherited_Aspect : constant array (Aspect_Id) of Boolean :=
 274                         (Aspect_Constant_Indexing    => True,
 275                          Aspect_Default_Iterator     => True,
 276                          Aspect_Implicit_Dereference => True,
 277                          Aspect_Iterator_Element     => True,
 278                          Aspect_Remote_Types         => True,
 279                          Aspect_Variable_Indexing    => True,
 280                          others                      => False);
 281
 282    --  The following subtype defines aspects corresponding to library unit
 283    --  pragmas, these can only validly appear as aspects for library units,
 284    --  and result in a corresponding pragma being inserted immediately after
 285    --  the occurrence of the aspect.
 286
 287    subtype Library_Unit_Aspects is
 288      Aspect_Id range Aspect_All_Calls_Remote .. Aspect_Universal_Data;
 289
 290    --  The following subtype defines aspects accepting an optional static
 291    --  boolean parameter indicating if the aspect should be active or
 292    --  cancelling. If the parameter is missing the effective value is True,
 293    --  enabling the aspect. If the parameter is present it must be a static
 294    --  expression of type Standard.Boolean. If the value is True, then the
 295    --  aspect is enabled. If it is False, the aspect is disabled.
 296
 297    subtype Boolean_Aspects is
 298      Aspect_Id range Aspect_Ada_2005 .. Aspect_Id'Last;
 299
 300    subtype Pre_Post_Aspects is
 301      Aspect_Id range Aspect_Post .. Aspect_Precondition;
 302
 303    --  The following type is used for indicating allowed expression forms
 304
 305    type Aspect_Expression is
 306      (Optional,               -- Optional boolean expression
 307       Expression,             -- Required expression
 308       Name);                  -- Required name
 309
 310    --  The following array indicates what argument type is required
 311
 312    Aspect_Argument : constant array (Aspect_Id) of Aspect_Expression :=
 313                        (No_Aspect                      => Optional,
 314                         Aspect_Abstract_State          => Expression,
 315                         Aspect_Address                 => Expression,
 316                         Aspect_Alignment               => Expression,
 317                         Aspect_Attach_Handler          => Expression,
 318                         Aspect_Bit_Order               => Expression,
 319                         Aspect_Component_Size          => Expression,
 320                         Aspect_Constant_Indexing       => Name,
 321                         Aspect_Contract_Case           => Expression,
 322                         Aspect_Contract_Cases          => Expression,
 323                         Aspect_Convention              => Name,
 324                         Aspect_CPU                     => Expression,
 325                         Aspect_Default_Component_Value => Expression,
 326                         Aspect_Default_Iterator        => Name,
 327                         Aspect_Default_Value           => Expression,
 328                         Aspect_Dimension               => Expression,
 329                         Aspect_Dimension_System        => Expression,
 330                         Aspect_Dispatching_Domain      => Expression,
 331                         Aspect_Dynamic_Predicate       => Expression,
 332                         Aspect_External_Name           => Expression,
 333                         Aspect_External_Tag            => Expression,
 334                         Aspect_Global                  => Expression,
 335                         Aspect_Implicit_Dereference    => Name,
 336                         Aspect_Input                   => Name,
 337                         Aspect_Interrupt_Priority      => Expression,
 338                         Aspect_Invariant               => Expression,
 339                         Aspect_Iterator_Element        => Name,
 340                         Aspect_Link_Name               => Expression,
 341                         Aspect_Machine_Radix           => Expression,
 342                         Aspect_Object_Size             => Expression,
 343                         Aspect_Output                  => Name,
 344                         Aspect_Post                    => Expression,
 345                         Aspect_Postcondition           => Expression,
 346                         Aspect_Pre                     => Expression,
 347                         Aspect_Precondition            => Expression,
 348                         Aspect_Predicate               => Expression,
 349                         Aspect_Priority                => Expression,
 350                         Aspect_Read                    => Name,
 351                         Aspect_Relative_Deadline       => Expression,
 352                         Aspect_Scalar_Storage_Order    => Expression,
 353                         Aspect_Simple_Storage_Pool     => Name,
 354                         Aspect_Size                    => Expression,
 355                         Aspect_Small                   => Expression,
 356                         Aspect_Static_Predicate        => Expression,
 357                         Aspect_Storage_Pool            => Name,
 358                         Aspect_Storage_Size            => Expression,
 359                         Aspect_Stream_Size             => Expression,
 360                         Aspect_Suppress                => Name,
 361                         Aspect_Synchronization         => Name,
 362                         Aspect_Test_Case               => Expression,
 363                         Aspect_Type_Invariant          => Expression,
 364                         Aspect_Unsuppress              => Name,
 365                         Aspect_Value_Size              => Expression,
 366                         Aspect_Variable_Indexing       => Name,
 367                         Aspect_Warnings                => Name,
 368                         Aspect_Write                   => Name,
 369
 370                         Library_Unit_Aspects           => Optional,
 371                         Boolean_Aspects                => Optional);
 372
 373    -----------------------------------------
 374    -- Table Linking Names and Aspect_Id's --
 375    -----------------------------------------
 376
 377    --  Table linking aspect names and id's
 378
 379    Aspect_Names : constant array (Aspect_Id) of Name_Id := (
 380      No_Aspect                           => No_Name,
 381      Aspect_Abstract_State               => Name_Abstract_State,
 382      Aspect_Ada_2005                     => Name_Ada_2005,
 383      Aspect_Ada_2012                     => Name_Ada_2012,
 384      Aspect_Address                      => Name_Address,
 385      Aspect_Alignment                    => Name_Alignment,
 386      Aspect_All_Calls_Remote             => Name_All_Calls_Remote,
 387      Aspect_Asynchronous                 => Name_Asynchronous,
 388      Aspect_Atomic                       => Name_Atomic,
 389      Aspect_Atomic_Components            => Name_Atomic_Components,
 390      Aspect_Attach_Handler               => Name_Attach_Handler,
 391      Aspect_Bit_Order                    => Name_Bit_Order,
 392      Aspect_Compiler_Unit                => Name_Compiler_Unit,
 393      Aspect_Component_Size               => Name_Component_Size,
 394      Aspect_Constant_Indexing            => Name_Constant_Indexing,
 395      Aspect_Contract_Case                => Name_Contract_Case,
 396      Aspect_Contract_Cases               => Name_Contract_Cases,
 397      Aspect_Convention                   => Name_Convention,
 398      Aspect_CPU                          => Name_CPU,
 399      Aspect_Default_Iterator             => Name_Default_Iterator,
 400      Aspect_Default_Value                => Name_Default_Value,
 401      Aspect_Default_Component_Value      => Name_Default_Component_Value,
 402      Aspect_Dimension                    => Name_Dimension,
 403      Aspect_Dimension_System             => Name_Dimension_System,
 404      Aspect_Discard_Names                => Name_Discard_Names,
 405      Aspect_Dispatching_Domain           => Name_Dispatching_Domain,
 406      Aspect_Dynamic_Predicate            => Name_Dynamic_Predicate,
 407      Aspect_Elaborate_Body               => Name_Elaborate_Body,
 408      Aspect_External_Name                => Name_External_Name,
 409      Aspect_External_Tag                 => Name_External_Tag,
 410      Aspect_Export                       => Name_Export,
 411      Aspect_Favor_Top_Level              => Name_Favor_Top_Level,
 412      Aspect_Global                       => Name_Global,
 413      Aspect_Implicit_Dereference         => Name_Implicit_Dereference,
 414      Aspect_Import                       => Name_Import,
 415      Aspect_Independent                  => Name_Independent,
 416      Aspect_Independent_Components       => Name_Independent_Components,
 417      Aspect_Inline                       => Name_Inline,
 418      Aspect_Inline_Always                => Name_Inline_Always,
 419      Aspect_Input                        => Name_Input,
 420      Aspect_Interrupt_Handler            => Name_Interrupt_Handler,
 421      Aspect_Interrupt_Priority           => Name_Interrupt_Priority,
 422      Aspect_Invariant                    => Name_Invariant,
 423      Aspect_Iterator_Element             => Name_Iterator_Element,
 424      Aspect_Link_Name                    => Name_Link_Name,
 425      Aspect_Lock_Free                    => Name_Lock_Free,
 426      Aspect_Machine_Radix                => Name_Machine_Radix,
 427      Aspect_No_Return                    => Name_No_Return,
 428      Aspect_Object_Size                  => Name_Object_Size,
 429      Aspect_Output                       => Name_Output,
 430      Aspect_Pack                         => Name_Pack,
 431      Aspect_Persistent_BSS               => Name_Persistent_BSS,
 432      Aspect_Post                         => Name_Post,
 433      Aspect_Postcondition                => Name_Postcondition,
 434      Aspect_Pre                          => Name_Pre,
 435      Aspect_Precondition                 => Name_Precondition,
 436      Aspect_Predicate                    => Name_Predicate,
 437      Aspect_Preelaborable_Initialization => Name_Preelaborable_Initialization,
 438      Aspect_Preelaborate                 => Name_Preelaborate,
 439      Aspect_Preelaborate_05              => Name_Preelaborate_05,
 440      Aspect_Priority                     => Name_Priority,
 441      Aspect_Pure                         => Name_Pure,
 442      Aspect_Pure_05                      => Name_Pure_05,
 443      Aspect_Pure_12                      => Name_Pure_12,
 444      Aspect_Pure_Function                => Name_Pure_Function,
 445      Aspect_Read                         => Name_Read,
 446      Aspect_Relative_Deadline            => Name_Relative_Deadline,
 447      Aspect_Remote_Access_Type           => Name_Remote_Access_Type,
 448      Aspect_Remote_Call_Interface        => Name_Remote_Call_Interface,
 449      Aspect_Remote_Types                 => Name_Remote_Types,
 450      Aspect_Scalar_Storage_Order         => Name_Scalar_Storage_Order,
 451      Aspect_Shared                       => Name_Shared,
 452      Aspect_Shared_Passive               => Name_Shared_Passive,
 453      Aspect_Simple_Storage_Pool          => Name_Simple_Storage_Pool,
 454      Aspect_Simple_Storage_Pool_Type     => Name_Simple_Storage_Pool_Type,
 455      Aspect_Size                         => Name_Size,
 456      Aspect_Small                        => Name_Small,
 457      Aspect_Static_Predicate             => Name_Static_Predicate,
 458      Aspect_Storage_Pool                 => Name_Storage_Pool,
 459      Aspect_Storage_Size                 => Name_Storage_Size,
 460      Aspect_Stream_Size                  => Name_Stream_Size,
 461      Aspect_Suppress                     => Name_Suppress,
 462      Aspect_Suppress_Debug_Info          => Name_Suppress_Debug_Info,
 463      Aspect_Synchronization              => Name_Synchronization,
 464      Aspect_Test_Case                    => Name_Test_Case,
 465      Aspect_Type_Invariant               => Name_Type_Invariant,
 466      Aspect_Unchecked_Union              => Name_Unchecked_Union,
 467      Aspect_Universal_Aliasing           => Name_Universal_Aliasing,
 468      Aspect_Universal_Data               => Name_Universal_Data,
 469      Aspect_Unmodified                   => Name_Unmodified,
 470      Aspect_Unreferenced                 => Name_Unreferenced,
 471      Aspect_Unreferenced_Objects         => Name_Unreferenced_Objects,
 472      Aspect_Unsuppress                   => Name_Unsuppress,
 473      Aspect_Value_Size                   => Name_Value_Size,
 474      Aspect_Variable_Indexing            => Name_Variable_Indexing,
 475      Aspect_Volatile                     => Name_Volatile,
 476      Aspect_Volatile_Components          => Name_Volatile_Components,
 477      Aspect_Warnings                     => Name_Warnings,
 478      Aspect_Write                        => Name_Write);
 479
 480    function Get_Aspect_Id (Name : Name_Id) return Aspect_Id;
 481    pragma Inline (Get_Aspect_Id);
 482    --  Given a name Nam, returns the corresponding aspect id value. If the name
 483    --  does not match any aspect, then No_Aspect is returned as the result.
 484
 485    ---------------------------------------------------
 486    -- Handling of Aspect Specifications in the Tree --
 487    ---------------------------------------------------
 488
 489    --  Several kinds of declaration node permit aspect specifications in Ada
 490    --  2012 mode. If there was room in all the corresponding declaration nodes,
 491    --  we could just have a field Aspect_Specifications pointing to a list of
 492    --  nodes for the aspects (N_Aspect_Specification nodes). But there isn't
 493    --  room, so we adopt a different approach.
 494
 495    --  The following subprograms provide access to a specialized interface
 496    --  implemented internally with a hash table in the body, that provides
 497    --  access to aspect specifications.
 498
 499    function Permits_Aspect_Specifications (N : Node_Id) return Boolean;
 500    --  Returns True if the node N is a declaration node that permits aspect
 501    --  specifications in the grammar. It is possible for other nodes to have
 502    --  aspect specifications as a result of Rewrite or Replace calls.
 503
 504    function Aspect_Specifications (N : Node_Id) return List_Id;
 505    --  Given a node N, returns the list of N_Aspect_Specification nodes that
 506    --  are attached to this declaration node. If the node is in the class of
 507    --  declaration nodes that permit aspect specifications, as defined by the
 508    --  predicate above, and if their Has_Aspects flag is set to True, then this
 509    --  will always be a non-empty list. If this flag is set to False, then
 510    --  No_List is returned. Normally, the only nodes that have Has_Aspects set
 511    --  True are the nodes for which Permits_Aspect_Specifications would return
 512    --  True (i.e. the declaration nodes defined in the RM as permitting the
 513    --  presence of Aspect_Specifications). However, it is possible for the
 514    --  flag Has_Aspects to be set on other nodes as a result of Rewrite and
 515    --  Replace calls, and this function may be used to retrieve the aspect
 516    --  specifications for the original rewritten node in such cases.
 517
 518    procedure Set_Aspect_Specifications (N : Node_Id; L : List_Id);
 519    --  The node N must be in the class of declaration nodes that permit aspect
 520    --  specifications and the Has_Aspects flag must be False on entry. L must
 521    --  be a non-empty list of N_Aspect_Specification nodes. This procedure sets
 522    --  the Has_Aspects flag to True, and makes an entry that can be retrieved
 523    --  by a subsequent Aspect_Specifications call. It is an error to call this
 524    --  procedure with a node that does not permit aspect specifications, or a
 525    --  node that has its Has_Aspects flag set True on entry, or with L being an
 526    --  empty list or No_List.
 527
 528    function Find_Aspect (Ent : Entity_Id; A : Aspect_Id) return Node_Id;
 529    --  Find value of a given aspect from aspect list of entity
 530
 531    procedure Move_Aspects (From : Node_Id; To : Node_Id);
 532    --  Moves aspects from 'From' node to 'To' node. Has_Aspects (To) must be
 533    --  False on entry. If Has_Aspects (From) is False, the call has no effect.
 534    --  Otherwise the aspects are moved and on return Has_Aspects (To) is True,
 535    --  and Has_Aspects (From) is False.
 536
 537    function Same_Aspect (A1 : Aspect_Id; A2 : Aspect_Id) return Boolean;
 538    --  Returns True if A1 and A2 are (essentially) the same aspect. This is not
 539    --  a simple equality test because e.g. Post and Postcondition are the same.
 540    --  This is used for detecting duplicate aspects.
 541
 542    procedure Tree_Write;
 543    --  Writes contents of Aspect_Specifications hash table to the tree file
 544
 545    procedure Tree_Read;
 546    --  Reads contents of Aspect_Specifications hash table from the tree file
 547
 548 end Aspects;