gcc/ada/sem_prag.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             S E M _ P R A G                              --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2023, 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- --
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  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 --  Pragma handling is isolated in a separate package
  27 --  (logically this processing belongs in chapter 4)
  28
  29 with Namet;  use Namet;
  30 with Opt;    use Opt;
  31 with Snames; use Snames;
  32 with Types;  use Types;
  33
  34 package Sem_Prag is
  35
  36    --  The following table lists all pragmas that emulate an Ada 2012 aspect
  37
  38    Aspect_Specifying_Pragma : constant array (Pragma_Id) of Boolean :=
  39      (Pragma_Abstract_State               => True,
  40       Pragma_All_Calls_Remote             => True,
  41       Pragma_Annotate                     => True,
  42       Pragma_Async_Readers                => True,
  43       Pragma_Async_Writers                => True,
  44       Pragma_Asynchronous                 => True,
  45       Pragma_Atomic                       => True,
  46       Pragma_Atomic_Components            => True,
  47       Pragma_Attach_Handler               => True,
  48       Pragma_Constant_After_Elaboration   => True,
  49       Pragma_Contract_Cases               => True,
  50       Pragma_Convention                   => True,
  51       Pragma_CPU                          => True,
  52       Pragma_CUDA_Device                  => True,
  53       Pragma_CUDA_Global                  => True,
  54       Pragma_Default_Initial_Condition    => True,
  55       Pragma_Default_Storage_Pool         => True,
  56       Pragma_Depends                      => True,
  57       Pragma_Discard_Names                => True,
  58       Pragma_Dispatching_Domain           => True,
  59       Pragma_Effective_Reads              => True,
  60       Pragma_Effective_Writes             => True,
  61       Pragma_Elaborate_Body               => True,
  62       Pragma_Export                       => True,
  63       Pragma_Extensions_Visible           => True,
  64       Pragma_Favor_Top_Level              => True,
  65       Pragma_Ghost                        => True,
  66       Pragma_Global                       => True,
  67       Pragma_GNAT_Annotate                => True,
  68       Pragma_Import                       => True,
  69       Pragma_Independent                  => True,
  70       Pragma_Independent_Components       => True,
  71       Pragma_Initial_Condition            => True,
  72       Pragma_Initializes                  => True,
  73       Pragma_Inline                       => True,
  74       Pragma_Inline_Always                => True,
  75       Pragma_Interrupt_Handler            => True,
  76       Pragma_Interrupt_Priority           => True,
  77       Pragma_Invariant                    => True,
  78       Pragma_Linker_Section               => True,
  79       Pragma_Lock_Free                    => True,
  80       Pragma_No_Elaboration_Code_All      => True,
  81       Pragma_No_Return                    => True,
  82       Pragma_Obsolescent                  => True,
  83       Pragma_Pack                         => True,
  84       Pragma_Part_Of                      => True,
  85       Pragma_Persistent_BSS               => True,
  86       Pragma_Post                         => True,
  87       Pragma_Post_Class                   => True,
  88       Pragma_Postcondition                => True,
  89       Pragma_Pre                          => True,
  90       Pragma_Pre_Class                    => True,
  91       Pragma_Precondition                 => True,
  92       Pragma_Predicate                    => True,
  93       Pragma_Preelaborable_Initialization => True,
  94       Pragma_Preelaborate                 => True,
  95       Pragma_Priority                     => True,
  96       Pragma_Pure                         => True,
  97       Pragma_Pure_Function                => True,
  98       Pragma_Refined_Depends              => True,
  99       Pragma_Refined_Global               => True,
 100       Pragma_Refined_Post                 => True,
 101       Pragma_Refined_State                => True,
 102       Pragma_Relative_Deadline            => True,
 103       Pragma_Remote_Access_Type           => True,
 104       Pragma_Remote_Call_Interface        => True,
 105       Pragma_Remote_Types                 => True,
 106       Pragma_Secondary_Stack_Size         => True,
 107       Pragma_Shared                       => True,
 108       Pragma_Shared_Passive               => True,
 109       Pragma_Simple_Storage_Pool_Type     => True,
 110       Pragma_SPARK_Mode                   => True,
 111       Pragma_Storage_Size                 => True,
 112       Pragma_Suppress                     => True,
 113       Pragma_Suppress_Debug_Info          => True,
 114       Pragma_Suppress_Initialization      => True,
 115       Pragma_Test_Case                    => True,
 116       Pragma_Thread_Local_Storage         => True,
 117       Pragma_Type_Invariant               => True,
 118       Pragma_Unchecked_Union              => True,
 119       Pragma_Universal_Aliasing           => True,
 120       Pragma_Unmodified                   => True,
 121       Pragma_Unreferenced                 => True,
 122       Pragma_Unreferenced_Objects         => True,
 123       Pragma_Unsuppress                   => True,
 124       Pragma_Volatile                     => True,
 125       Pragma_Volatile_Components          => True,
 126       Pragma_Volatile_Full_Access         => True,
 127       Pragma_Warnings                     => True,
 128       others                              => False);
 129
 130    --  The following table lists all pragmas that act as an assertion
 131    --  expression.
 132
 133    Assertion_Expression_Pragma : constant array (Pragma_Id) of Boolean :=
 134      (Pragma_Assert                    => True,
 135       Pragma_Assert_And_Cut            => True,
 136       Pragma_Assume                    => True,
 137       Pragma_Check                     => True,
 138       Pragma_Compile_Time_Error        => True,
 139       Pragma_Contract_Cases            => True,
 140       Pragma_Default_Initial_Condition => True,
 141       Pragma_Initial_Condition         => True,
 142       Pragma_Invariant                 => True,
 143       Pragma_Loop_Invariant            => True,
 144       Pragma_Loop_Variant              => True,
 145       Pragma_Post                      => True,
 146       Pragma_Post_Class                => True,
 147       Pragma_Postcondition             => True,
 148       Pragma_Pre                       => True,
 149       Pragma_Pre_Class                 => True,
 150       Pragma_Precondition              => True,
 151       Pragma_Predicate                 => True,
 152       Pragma_Refined_Post              => True,
 153       Pragma_Subprogram_Variant        => True,
 154       Pragma_Test_Case                 => True,
 155       Pragma_Type_Invariant            => True,
 156       Pragma_Type_Invariant_Class      => True,
 157       others                           => False);
 158
 159    --  Should to following constant arrays be renamed to better suit their
 160    --  use as a predicate (e.g. Is_Pragma_*) ???
 161
 162    --  The following table lists all the implementation-defined pragmas that
 163    --  should apply to the anonymous object produced by the analysis of a
 164    --  single protected or task type. The table should be synchronized with
 165    --  Aspect_On_Anonymous_Object_OK in unit Aspects.
 166
 167    Pragma_On_Anonymous_Object_OK : constant array (Pragma_Id) of Boolean :=
 168      (Pragma_Depends => True,
 169       Pragma_Global  => True,
 170       Pragma_Part_Of => True,
 171       others         => False);
 172
 173    --  The following table lists all the implementation-defined pragmas that
 174    --  may apply to a body stub (no language defined pragmas apply). The table
 175    --  should be synchronized with Aspect_On_Body_Or_Stub_OK in unit Aspects.
 176
 177    Pragma_On_Body_Or_Stub_OK : constant array (Pragma_Id) of Boolean :=
 178      (Pragma_Refined_Depends => True,
 179       Pragma_Refined_Global  => True,
 180       Pragma_Refined_Post    => True,
 181       Pragma_SPARK_Mode      => True,
 182       Pragma_Warnings        => True,
 183       others                 => False);
 184
 185    --  The following table lists all pragmas which are significant in SPARK and
 186    --  as a result get translated into verification conditions. The table is an
 187    --  amalgamation of the pragmas listed in SPARK RM 16.1 and internally added
 188    --  entries.
 189
 190    Pragma_Significant_In_SPARK : constant array (Pragma_Id) of Boolean :=
 191      (Pragma_All_Calls_Remote              => False,
 192       Pragma_Asynchronous                  => False,
 193       Pragma_Default_Storage_Pool          => False,
 194       Pragma_Discard_Names                 => False,
 195       Pragma_Dispatching_Domain            => False,
 196       Pragma_Priority_Specific_Dispatching => False,
 197       Pragma_Remote_Call_Interface         => False,
 198       Pragma_Remote_Types                  => False,
 199       Pragma_Shared_Passive                => False,
 200       Pragma_Task_Dispatching_Policy       => False,
 201       Pragma_Unmodified                    => False,
 202       Pragma_Unreferenced                  => False,
 203       Pragma_Warnings                      => False,
 204       others                               => True);
 205
 206    --  The following table lists all pragmas which are relevant to the analysis
 207    --  of subprogram bodies.
 208
 209    Pragma_Significant_To_Subprograms : constant array (Pragma_Id) of Boolean :=
 210      (Pragma_Contract_Cases    => True,
 211       Pragma_Depends           => True,
 212       Pragma_Ghost             => True,
 213       Pragma_Global            => True,
 214       Pragma_Inline            => True,
 215       Pragma_Inline_Always     => True,
 216       Pragma_Post              => True,
 217       Pragma_Post_Class        => True,
 218       Pragma_Postcondition     => True,
 219       Pragma_Pre               => True,
 220       Pragma_Pre_Class         => True,
 221       Pragma_Precondition      => True,
 222       Pragma_Pure              => True,
 223       Pragma_Pure_Function     => True,
 224       Pragma_Refined_Depends   => True,
 225       Pragma_Refined_Global    => True,
 226       Pragma_Refined_Post      => True,
 227       Pragma_Refined_State     => True,
 228       Pragma_Volatile          => True,
 229       Pragma_Volatile_Function => True,
 230       others                   => False);
 231
 232    -----------------
 233    -- Subprograms --
 234    -----------------
 235
 236    procedure Analyze_Pragma (N : Node_Id);
 237    --  Analyze procedure for pragma reference node N
 238
 239    procedure Analyze_Contract_Cases_In_Decl_Part
 240      (N         : Node_Id;
 241       Freeze_Id : Entity_Id := Empty);
 242    --  Perform full analysis of delayed pragma Contract_Cases. Freeze_Id is the
 243    --  entity of [generic] package body or [generic] subprogram body which
 244    --  caused "freezing" of the related contract where the pragma resides.
 245
 246    procedure Analyze_Depends_In_Decl_Part (N : Node_Id);
 247    --  Perform full analysis of delayed pragma Depends. This routine is also
 248    --  capable of performing basic analysis of pragma Refined_Depends.
 249
 250    procedure Analyze_External_Property_In_Decl_Part
 251      (N        : Node_Id;
 252       Expr_Val : out Boolean);
 253    --  Perform full analysis of delayed pragmas Async_Readers, Async_Writers,
 254    --  Effective_Reads, Effective_Writes and No_Caching. Flag Expr_Val contains
 255    --  the Boolean argument of the pragma or a default True if no argument
 256    --  is present.
 257
 258    procedure Analyze_Global_In_Decl_Part (N : Node_Id);
 259    --  Perform full analysis of delayed pragma Global. This routine is also
 260    --  capable of performing basic analysis of pragma Refined_Global.
 261
 262    procedure Analyze_Initial_Condition_In_Decl_Part (N : Node_Id);
 263    --  Perform full analysis of delayed pragma Initial_Condition
 264
 265    procedure Analyze_Initializes_In_Decl_Part (N : Node_Id);
 266    --  Perform full analysis of delayed pragma Initializes
 267
 268    procedure Analyze_Part_Of_In_Decl_Part
 269      (N         : Node_Id;
 270       Freeze_Id : Entity_Id := Empty);
 271    --  Perform full analysis of delayed pragma Part_Of. Freeze_Id is the entity
 272    --  of [generic] package body or [generic] subprogram body which caused the
 273    --  "freezing" of the related contract where the pragma resides.
 274
 275    procedure Analyze_Pre_Post_Condition_In_Decl_Part
 276      (N         : Node_Id;
 277       Freeze_Id : Entity_Id := Empty);
 278    --  Perform full analysis of pragmas Precondition and Postcondition.
 279    --  Freeze_Id denotes the entity of [generic] package body or [generic]
 280    --  subprogram body which caused "freezing" of the related contract where
 281    --  the pragma resides.
 282
 283    procedure Analyze_Refined_Depends_In_Decl_Part (N : Node_Id);
 284    --  Preform full analysis of delayed pragma Refined_Depends. This routine
 285    --  uses Analyze_Depends_In_Decl_Part as a starting point, then performs
 286    --  various consistency checks between Depends and Refined_Depends.
 287
 288    procedure Analyze_Refined_Global_In_Decl_Part (N : Node_Id);
 289    --  Perform full analysis of delayed pragma Refined_Global. This routine
 290    --  uses Analyze_Global_In_Decl_Part as a starting point, then performs
 291    --  various consistency checks between Global and Refined_Global.
 292
 293    procedure Analyze_Refined_State_In_Decl_Part
 294      (N         : Node_Id;
 295       Freeze_Id : Entity_Id := Empty);
 296    --  Perform full analysis of delayed pragma Refined_State. Freeze_Id denotes
 297    --  the entity of [generic] package body or [generic] subprogram body which
 298    --  caused "freezing" of the related contract where the pragma resides.
 299
 300    procedure Analyze_Subprogram_Variant_In_Decl_Part
 301      (N         : Node_Id;
 302       Freeze_Id : Entity_Id := Empty);
 303    --  Perform full analysis of delayed pragma Subprogram_Variant. Freeze_Id is
 304    --  the entity of [generic] package body or [generic] subprogram body which
 305    --  caused "freezing" of the related contract where the pragma resides.
 306
 307    procedure Analyze_Test_Case_In_Decl_Part (N : Node_Id);
 308    --  Perform preanalysis of pragma Test_Case
 309
 310    function Build_Pragma_Check_Equivalent
 311      (Prag           : Node_Id;
 312       Subp_Id        : Entity_Id := Empty;
 313       Inher_Id       : Entity_Id := Empty;
 314       Keep_Pragma_Id : Boolean := False) return Node_Id;
 315    --  Transform a pre- or [refined] postcondition denoted by Prag into an
 316    --  equivalent pragma Check. When the pre- or postcondition is inherited,
 317    --  the routine replaces the references of all formals of Inher_Id
 318    --  and primitive operations of its controlling type by references
 319    --  to the corresponding entities of Subp_Id and the descendant type.
 320    --  Keep_Pragma_Id is True when the newly created pragma should be
 321    --  in fact of the same kind as the source pragma Prag. This is used
 322    --  in GNATprove_Mode to generate the inherited pre- and postconditions.
 323
 324    procedure Check_Applicable_Policy (N : Node_Id);
 325    --  N is either an N_Aspect or an N_Pragma node. There are two cases. If
 326    --  the name of the aspect or pragma is not one of those recognized as
 327    --  an assertion kind by an Assertion_Policy pragma, then the call has
 328    --  no effect. Note that in the case of a pragma derived from an aspect,
 329    --  the name we use for the purpose of this procedure is the aspect name,
 330    --  which may be different from the pragma name (e.g. Precondition for
 331    --  Pre aspect). In addition, 'Class aspects are recognized (and the
 332    --  corresponding special names used in the processing).
 333    --
 334    --  If the name is a valid assertion kind name, then the Check_Policy pragma
 335    --  chain is checked for a matching entry (or for an Assertion entry which
 336    --  matches all possibilities). If a matching entry is found then the policy
 337    --  is checked. If it is On or Check, then the Is_Checked flag is set in
 338    --  the aspect or pragma node. If it is Off, Ignore, or Disable, then the
 339    --  Is_Ignored flag is set in the aspect or pragma node. Additionally for
 340    --  policy Disable, the Is_Disabled flag is set.
 341    --
 342    --  If no matching Check_Policy pragma is found then the effect depends on
 343    --  whether -gnata was used, if so, then the call has no effect, otherwise
 344    --  Is_Ignored (but not Is_Disabled) is set True.
 345
 346    procedure Check_External_Properties
 347      (Item : Node_Id;
 348       AR   : Boolean;
 349       AW   : Boolean;
 350       ER   : Boolean;
 351       EW   : Boolean);
 352    --  Flags AR, AW, ER and EW denote the static values of external properties
 353    --  Async_Readers, Async_Writers, Effective_Reads and Effective_Writes. Item
 354    --  is the related variable or state. Ensure legality of the combination and
 355    --  issue an error for an illegal combination.
 356
 357    function Check_Kind (Nam : Name_Id) return Name_Id;
 358    --  This function is used in connection with pragmas Assert, Check,
 359    --  and assertion aspects and pragmas, to determine if Check pragmas
 360    --  (or corresponding assertion aspects or pragmas) are currently active
 361    --  as determined by the presence of -gnata on the command line (which
 362    --  sets the default), and the appearance of pragmas Check_Policy and
 363    --  Assertion_Policy as configuration pragmas either in a configuration
 364    --  pragma file, or at the start of the current unit, or locally given
 365    --  Check_Policy and Assertion_Policy pragmas that are currently active.
 366    --
 367    --  The value returned is one of the names Check, Ignore, Disable (On
 368    --  returns Check, and Off returns Ignore).
 369    --
 370    --  Note: for assertion kinds Pre'Class, Post'Class, Invariant'Class,
 371    --  and Type_Invariant'Class, the name passed is Name_uPre, Name_uPost,
 372    --  Name_uInvariant, or Name_uType_Invariant, which corresponds to _Pre,
 373    --  _Post, _Invariant, or _Type_Invariant, which are special names used
 374    --  in identifiers to represent these attribute references.
 375
 376    procedure Check_Missing_Part_Of (Item_Id : Entity_Id);
 377    --  Determine whether the placement within the state space of an abstract
 378    --  state, variable or package instantiation denoted by Item_Id requires the
 379    --  use of indicator/option Part_Of. If this is the case, emit an error.
 380
 381    procedure Collect_Inherited_Class_Wide_Conditions (Subp : Entity_Id);
 382    --  In GNATprove mode, when analyzing an overriding subprogram, check
 383    --  whether the overridden operations have class-wide pre/postconditions,
 384    --  and generate the corresponding pragmas. The pragmas are inserted after
 385    --  the subprogram declaration, together with those generated for other
 386    --  aspects of the subprogram.
 387
 388    procedure Collect_Subprogram_Inputs_Outputs
 389      (Subp_Id      : Entity_Id;
 390       Synthesize   : Boolean := False;
 391       Subp_Inputs  : in out Elist_Id;
 392       Subp_Outputs : in out Elist_Id;
 393       Global_Seen  : out Boolean);
 394    --  Subsidiary to the analysis of pragmas Depends, Global, Refined_Depends
 395    --  and Refined_Global. Collect all inputs and outputs of subprogram Subp_Id
 396    --  in lists Subp_Inputs (inputs) and Subp_Outputs (outputs). The inputs and
 397    --  outputs are gathered from:
 398    --    1) The formal parameters of the subprogram
 399    --    2) The generic formal parameters of the generic subprogram
 400    --    3) The current instance of a concurrent type
 401    --    4) The items of pragma [Refined_]Global
 402    --         or
 403    --    5) The items of pragma [Refined_]Depends if there is no pragma
 404    --       [Refined_]Global present and flag Synthesize is set to True.
 405    --  If the subprogram has no inputs and/or outputs, then the returned list
 406    --  is No_Elist. Flag Global_Seen is set when the related subprogram has
 407    --  pragma [Refined_]Global.
 408
 409    function Delay_Config_Pragma_Analyze (N : Node_Id) return Boolean;
 410    --  N is a pragma appearing in a configuration pragma file. Most such
 411    --  pragmas are analyzed when the file is read, before parsing and analyzing
 412    --  the main unit. However, the analysis of certain pragmas results in
 413    --  adding information to the compiled main unit, and this cannot be done
 414    --  till the main unit is processed. Such pragmas return True from this
 415    --  function and in Frontend pragmas where Delay_Config_Pragma_Analyze is
 416    --  True have their analysis delayed until after the main program is parsed
 417    --  and analyzed.
 418
 419    function Find_Related_Package_Or_Body
 420      (Prag      : Node_Id;
 421       Do_Checks : Boolean := False) return Node_Id;
 422    --  Subsidiary to the analysis of pragmas
 423    --    Abstract_State
 424    --    Initial_Condition
 425    --    Initializes
 426    --    Refined_State
 427    --  Find the declaration of the related package [body] subject to pragma
 428    --  Prag. The return value is either N_Package_Declaration, N_Package_Body,
 429    --  or Empty if the placement of the pragma is illegal. If flag Do_Checks is
 430    --  set, the routine reports duplicate pragmas.
 431
 432    function Find_Related_Declaration_Or_Body
 433      (Prag      : Node_Id;
 434       Do_Checks : Boolean := False) return Node_Id;
 435    --  Subsidiary to the analysis of pragmas
 436    --    Contract_Cases
 437    --    Depends
 438    --    Extensions_Visible
 439    --    Global
 440    --    Initializes
 441    --    Max_Entry_Queue_Depth
 442    --    Max_Entry_Queue_Length
 443    --    Max_Queue_Length
 444    --    Post
 445    --    Post_Class
 446    --    Postcondition
 447    --    Pre
 448    --    Pre_Class
 449    --    Precondition
 450    --    Refined_Depends
 451    --    Refined_Global
 452    --    Refined_Post
 453    --    Refined_State
 454    --    Test_Case
 455    --    Volatile_Function
 456    --  as well as attributes 'Old and 'Result. Find the declaration of the
 457    --  related entry, subprogram or task type [body] subject to pragma Prag.
 458    --  If flag Do_Checks is set, the routine reports duplicate pragmas and
 459    --  detects improper use of refinement pragmas in stand alone expression
 460    --  functions.
 461
 462    function Get_Argument
 463      (Prag       : Node_Id;
 464       Context_Id : Entity_Id := Empty) return Node_Id;
 465    --  Obtain the argument of pragma Prag depending on context and the nature
 466    --  of the pragma. The argument is extracted in the following manner:
 467    --
 468    --    When the pragma is generated from an aspect, return the corresponding
 469    --    aspect when Context_Id denotes a generic unit.
 470    --
 471    --    Otherwise return the first argument of Prag
 472    --
 473    --  Context denotes the entity of the function, package or procedure where
 474    --  Prag resides.
 475
 476    function Get_SPARK_Mode_From_Annotation
 477      (N : Node_Id) return SPARK_Mode_Type;
 478    --  Given an aspect or pragma SPARK_Mode node, return corresponding mode id
 479
 480    procedure Initialize;
 481    --  Initializes data structures used for pragma processing. Must be called
 482    --  before analyzing each new main source program.
 483
 484    function Is_Config_Static_String (Arg : Node_Id) return Boolean;
 485    --  This is called for a configuration pragma that requires either string
 486    --  literal or a concatenation of string literals. We cannot use normal
 487    --  static string processing because it is too early in the case of the
 488    --  pragma appearing in a configuration pragmas file. If Arg is of an
 489    --  appropriate form, then this call obtains the string (doing any necessary
 490    --  concatenations) and places it in Name_Buffer, setting Name_Len to its
 491    --  length, and then returns True. If it is not of the correct form, then an
 492    --  appropriate error message is posted, and False is returned.
 493
 494    function Is_Elaboration_SPARK_Mode (N : Node_Id) return Boolean;
 495    --  Determine whether pragma SPARK_Mode appears in the statement part of a
 496    --  package body.
 497
 498    function Is_Enabled_Pragma (Prag : Node_Id) return Boolean;
 499    --  Determine whether a Boolean-like SPARK pragma Prag is enabled. To be
 500    --  considered enabled, the pragma must either:
 501    --    * Appear without its Boolean expression
 502    --    * The Boolean expression evaluates to "True"
 503    --
 504    --  Boolean-like SPARK pragmas differ from pure Boolean Ada pragmas in that
 505    --  their optional Boolean expression must be static and cannot benefit from
 506    --  forward references. The following are Boolean-like SPARK pragmas:
 507    --    Async_Readers
 508    --    Async_Writers
 509    --    Constant_After_Elaboration
 510    --    Effective_Reads
 511    --    Effective_Writes
 512    --    Extensions_Visible
 513    --    Volatile_Function
 514
 515    function Is_Non_Significant_Pragma_Reference (N : Node_Id) return Boolean;
 516    --  The node N is a node for an entity and the issue is whether the
 517    --  occurrence is a reference for the purposes of giving warnings about
 518    --  unreferenced variables. This function returns True if the reference is
 519    --  not a reference from this point of view (e.g. the occurrence in a pragma
 520    --  Pack) and False if it is a real reference (e.g. the occurrence in a
 521    --  pragma Export);
 522
 523    function Is_Pragma_String_Literal (Par : Node_Id) return Boolean;
 524    --  Given an N_Pragma_Argument_Association node, Par, which has the form of
 525    --  an operator symbol, determines whether or not it should be treated as an
 526    --  string literal. This is called by Sem_Ch6.Analyze_Operator_Symbol. If
 527    --  True is returned, the argument is converted to a string literal. If
 528    --  False is returned, then the argument is treated as an entity reference
 529    --  to the operator.
 530
 531    function Is_Private_SPARK_Mode (N : Node_Id) return Boolean;
 532    --  Determine whether pragma SPARK_Mode appears in the private part of a
 533    --  package.
 534
 535    function Is_Valid_Assertion_Kind (Nam : Name_Id) return Boolean;
 536    --  Returns True if Nam is one of the names recognized as a valid assertion
 537    --  kind by the Assertion_Policy pragma. Note that the 'Class cases are
 538    --  represented by the corresponding special names Name_uPre, Name_uPost,
 539    --  Name_uInvariant, and Name_uType_Invariant (_Pre, _Post, _Invariant,
 540    --  and _Type_Invariant).
 541
 542    procedure Process_Compilation_Unit_Pragmas (N : Node_Id);
 543    --  Called at the start of processing compilation unit N to deal with any
 544    --  special issues regarding pragmas. In particular, we have to deal with
 545    --  Suppress_All at this stage, since it can appear after the unit instead
 546    --  of before (actually we allow it to appear anywhere).
 547
 548    procedure Relocate_Pragmas_To_Anonymous_Object
 549      (Typ_Decl : Node_Id;
 550       Obj_Decl : Node_Id);
 551    --  Relocate all pragmas that appear in the visible declarations of task or
 552    --  protected type declaration Typ_Decl after the declaration of anonymous
 553    --  object Obj_Decl. Table Pragmas_On_Anonymous_Object_OK contains the list
 554    --  of candidate pragmas.
 555
 556    procedure Relocate_Pragmas_To_Body
 557      (Subp_Body   : Node_Id;
 558       Target_Body : Node_Id := Empty);
 559    --  Resocate all pragmas that follow and apply to subprogram body Subp_Body
 560    --  to its own declaration list. Candidate pragmas are classified in table
 561    --  Pragma_On_Body_Or_Stub_OK. If Target_Body is set, the pragma are moved
 562    --  to the declarations of Target_Body. This formal should be set when
 563    --  dealing with subprogram body stubs or expression functions.
 564
 565    procedure Set_Encoded_Interface_Name (E : Entity_Id; S : Node_Id);
 566    --  This routine is used to set an encoded interface name. The node S is
 567    --  an N_String_Literal node for the external name to be set, and E is an
 568    --  entity whose Interface_Name field is to be set. In the normal case where
 569    --  S contains a name that is a valid C identifier, then S is simply set as
 570    --  the value of the Interface_Name. Otherwise it is encoded as needed by
 571    --  particular operating systems. See the body for details of the encoding.
 572
 573    procedure Set_Overflow_Mode (N : Node_Id);
 574    --  Sets Sem.Scope_Suppress according to the overflow modes specified in
 575    --  the pragma Overflow_Mode passed in argument. This should only be called
 576    --  after N has been successfully analyzed.
 577
 578    function Test_Case_Arg
 579      (Prag        : Node_Id;
 580       Arg_Nam     : Name_Id;
 581       From_Aspect : Boolean := False) return Node_Id;
 582    --  Obtain argument "Name", "Mode", "Ensures" or "Requires" from Test_Case
 583    --  pragma Prag as denoted by Arg_Nam. When From_Aspect is set, an attempt
 584    --  is made to retrieve the argument from the corresponding aspect if there
 585    --  is one. The returned argument has several formats:
 586    --
 587    --    N_Pragma_Argument_Association if retrieved directly from the pragma
 588    --
 589    --    N_Component_Association if retrieved from the corresponding aspect and
 590    --    the argument appears in a named association form.
 591    --
 592    --    An arbitrary expression if retrieved from the corresponding aspect and
 593    --    the argument appears in positional form.
 594    --
 595    --    Empty if there is no such argument
 596
 597    procedure Validate_Compile_Time_Warning_Errors;
 598    --  This routine is called after calling the back end to validate pragmas
 599    --  Compile_Time_Error and Compile_Time_Warning for size and alignment
 600    --  appropriateness. The reason it is called that late is to take advantage
 601    --  of any back-annotation of size and alignment performed by the back end.
 602
 603 end Sem_Prag;