gcc/ada/restrict.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             R E S T R I C T                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2007, Free Software Foundation, Inc.         --
  10 --                                                                          --
  11 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  12 -- terms of the  GNU General Public License as published  by the Free Soft- --
  13 -- ware  Foundation;  either version 3,  or (at your option) any later ver- --
  14 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  15 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  16 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  17 -- for  more details.  You should have  received  a copy of the GNU General --
  18 -- Public License  distributed with GNAT; see file COPYING3.  If not, go to --
  19 -- http://www.gnu.org/licenses for a complete copy of the license.          --
  20 --                                                                          --
  21 -- GNAT was originally developed  by the GNAT team at  New York University. --
  22 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  23 --                                                                          --
  24 ------------------------------------------------------------------------------
  25
  26 with Atree;    use Atree;
  27 with Casing;   use Casing;
  28 with Errout;   use Errout;
  29 with Fname;    use Fname;
  30 with Fname.UF; use Fname.UF;
  31 with Lib;      use Lib;
  32 with Opt;      use Opt;
  33 with Sinfo;    use Sinfo;
  34 with Sinput;   use Sinput;
  35 with Snames;   use Snames;
  36 with Uname;    use Uname;
  37
  38 package body Restrict is
  39
  40    Restricted_Profile_Result : Boolean := False;
  41    --  This switch memoizes the result of Restricted_Profile function
  42    --  calls for improved efficiency. Its setting is valid only if
  43    --  Restricted_Profile_Cached is True. Note that if this switch
  44    --  is ever set True, it need never be turned off again.
  45
  46    Restricted_Profile_Cached : Boolean := False;
  47    --  This flag is set to True if the Restricted_Profile_Result
  48    --  contains the correct cached result of Restricted_Profile calls.
  49
  50    -----------------------
  51    -- Local Subprograms --
  52    -----------------------
  53
  54    procedure Restriction_Msg (Msg : String; R : String; N : Node_Id);
  55    --  Output error message at node N with given text, replacing the
  56    --  '%' in the message with the name of the restriction given as R,
  57    --  cased according to the current identifier casing. We do not use
  58    --  the normal insertion mechanism, since this requires an entry
  59    --  in the Names table, and this table will be locked if we are
  60    --  generating a message from gigi.
  61
  62    function Same_Unit (U1, U2 : Node_Id) return Boolean;
  63    --  Returns True iff U1 and U2 represent the same library unit. Used for
  64    --  handling of No_Dependence => Unit restriction case.
  65
  66    function Suppress_Restriction_Message (N : Node_Id) return Boolean;
  67    --  N is the node for a possible restriction violation message, but
  68    --  the message is to be suppressed if this is an internal file and
  69    --  this file is not the main unit.
  70
  71    -------------------
  72    -- Abort_Allowed --
  73    -------------------
  74
  75    function Abort_Allowed return Boolean is
  76    begin
  77       if Restrictions.Set (No_Abort_Statements)
  78         and then Restrictions.Set (Max_Asynchronous_Select_Nesting)
  79         and then Restrictions.Value (Max_Asynchronous_Select_Nesting) = 0
  80       then
  81          return False;
  82       else
  83          return True;
  84       end if;
  85    end Abort_Allowed;
  86
  87    -------------------------
  88    -- Check_Compiler_Unit --
  89    -------------------------
  90
  91    procedure Check_Compiler_Unit (N : Node_Id) is
  92    begin
  93       if Is_Compiler_Unit (Get_Source_Unit (N)) then
  94          Error_Msg_N ("use of construct not allowed in compiler", N);
  95       end if;
  96    end Check_Compiler_Unit;
  97
  98    ------------------------------------
  99    -- Check_Elaboration_Code_Allowed --
 100    ------------------------------------
 101
 102    procedure Check_Elaboration_Code_Allowed (N : Node_Id) is
 103    begin
 104       --  Avoid calling Namet.Unlock/Lock except when there is an error.
 105       --  Even in the error case it is a bit dubious, either gigi needs
 106       --  the table locked or it does not! ???
 107
 108       if Restrictions.Set (No_Elaboration_Code)
 109         and then not Suppress_Restriction_Message (N)
 110       then
 111          Namet.Unlock;
 112          Check_Restriction (No_Elaboration_Code, N);
 113          Namet.Lock;
 114       end if;
 115    end Check_Elaboration_Code_Allowed;
 116
 117    ----------------------------------
 118    -- Check_No_Implicit_Heap_Alloc --
 119    ----------------------------------
 120
 121    procedure Check_No_Implicit_Heap_Alloc (N : Node_Id) is
 122    begin
 123       Check_Restriction (No_Implicit_Heap_Allocations, N);
 124    end Check_No_Implicit_Heap_Alloc;
 125
 126    ---------------------------
 127    -- Check_Restricted_Unit --
 128    ---------------------------
 129
 130    procedure Check_Restricted_Unit (U : Unit_Name_Type; N : Node_Id) is
 131    begin
 132       if Suppress_Restriction_Message (N) then
 133          return;
 134
 135       elsif Is_Spec_Name (U) then
 136          declare
 137             Fnam : constant File_Name_Type :=
 138                      Get_File_Name (U, Subunit => False);
 139
 140          begin
 141             --  Get file name
 142
 143             Get_Name_String (Fnam);
 144
 145             --  Nothing to do if name not at least 5 characters long ending
 146             --  in .ads or .adb extension, which we strip.
 147
 148             if Name_Len < 5
 149               or else (Name_Buffer (Name_Len - 3 .. Name_Len) /= ".ads"
 150                          and then
 151                        Name_Buffer (Name_Len - 4 .. Name_Len) /= ".adb")
 152             then
 153                return;
 154             end if;
 155
 156             --  Strip extension and pad to eight characters
 157
 158             Name_Len := Name_Len - 4;
 159             while Name_Len < 8 loop
 160                Name_Len := Name_Len + 1;
 161                Name_Buffer (Name_Len) := ' ';
 162             end loop;
 163
 164             --  If predefined unit, check the list of restricted units
 165
 166             if Is_Predefined_File_Name (Fnam) then
 167                for J in Unit_Array'Range loop
 168                   if Name_Len = 8
 169                     and then Name_Buffer (1 .. 8) = Unit_Array (J).Filenm
 170                   then
 171                      Check_Restriction (Unit_Array (J).Res_Id, N);
 172                   end if;
 173                end loop;
 174
 175                --  If not predefied unit, then one special check still remains.
 176                --  GNAT.Current_Exception is not allowed if we have restriction
 177                --  No_Exception_Propagation active.
 178
 179             else
 180                if Name_Buffer (1 .. 8) = "g-curexc" then
 181                   Check_Restriction (No_Exception_Propagation, N);
 182                end if;
 183             end if;
 184          end;
 185       end if;
 186    end Check_Restricted_Unit;
 187
 188    -----------------------
 189    -- Check_Restriction --
 190    -----------------------
 191
 192    procedure Check_Restriction
 193      (R : Restriction_Id;
 194       N : Node_Id;
 195       V : Uint := Uint_Minus_1)
 196    is
 197       Rimage : constant String := Restriction_Id'Image (R);
 198
 199       VV : Integer;
 200       --  V converted to integer form. If V is greater than Integer'Last,
 201       --  it is reset to minus 1 (unknown value).
 202
 203       procedure Update_Restrictions (Info : in out Restrictions_Info);
 204       --  Update violation information in Info.Violated and Info.Count
 205
 206       -------------------------
 207       -- Update_Restrictions --
 208       -------------------------
 209
 210       procedure Update_Restrictions (Info : in out Restrictions_Info) is
 211       begin
 212          --  If not violated, set as violated now
 213
 214          if not Info.Violated (R) then
 215             Info.Violated (R) := True;
 216
 217             if R in All_Parameter_Restrictions then
 218                if VV < 0 then
 219                   Info.Unknown (R) := True;
 220                   Info.Count (R) := 1;
 221                else
 222                   Info.Count (R) := VV;
 223                end if;
 224             end if;
 225
 226          --  Otherwise if violated already and a parameter restriction,
 227          --  update count by maximizing or summing depending on restriction.
 228
 229          elsif R in All_Parameter_Restrictions then
 230
 231             --  If new value is unknown, result is unknown
 232
 233             if VV < 0 then
 234                Info.Unknown (R) := True;
 235
 236             --  If checked by maximization, do maximization
 237
 238             elsif R in Checked_Max_Parameter_Restrictions then
 239                Info.Count (R) := Integer'Max (Info.Count (R), VV);
 240
 241             --  If checked by adding, do add, checking for overflow
 242
 243             elsif R in Checked_Add_Parameter_Restrictions then
 244                declare
 245                   pragma Unsuppress (Overflow_Check);
 246                begin
 247                   Info.Count (R) := Info.Count (R) + VV;
 248                exception
 249                   when Constraint_Error =>
 250                      Info.Count (R) := Integer'Last;
 251                      Info.Unknown (R) := True;
 252                end;
 253
 254             --  Should not be able to come here, known counts should only
 255             --  occur for restrictions that are Checked_max or Checked_Sum.
 256
 257             else
 258                raise Program_Error;
 259             end if;
 260          end if;
 261       end Update_Restrictions;
 262
 263    --  Start of processing for Check_Restriction
 264
 265    begin
 266       if UI_Is_In_Int_Range (V) then
 267          VV := Integer (UI_To_Int (V));
 268       else
 269          VV := -1;
 270       end if;
 271
 272       --  Count can only be specified in the checked val parameter case
 273
 274       pragma Assert (VV < 0 or else R in Checked_Val_Parameter_Restrictions);
 275
 276       --  Nothing to do if value of zero specified for parameter restriction
 277
 278       if VV = 0 then
 279          return;
 280       end if;
 281
 282       --  Update current restrictions
 283
 284       Update_Restrictions (Restrictions);
 285
 286       --  If in main extended unit, update main restrictions as well
 287
 288       if Current_Sem_Unit = Main_Unit
 289         or else In_Extended_Main_Source_Unit (N)
 290       then
 291          Update_Restrictions (Main_Restrictions);
 292       end if;
 293
 294       --  Nothing to do if restriction message suppressed
 295
 296       if Suppress_Restriction_Message (N) then
 297          null;
 298
 299       --  If restriction not set, nothing to do
 300
 301       elsif not Restrictions.Set (R) then
 302          null;
 303
 304       --  Here if restriction set, check for violation (either this is a
 305       --  Boolean restriction, or a parameter restriction with a value of
 306       --  zero and an unknown count, or a parameter restriction with a
 307       --  known value that exceeds the restriction count).
 308
 309       elsif R in All_Boolean_Restrictions
 310         or else (Restrictions.Unknown (R)
 311                    and then Restrictions.Value (R) = 0)
 312         or else Restrictions.Count (R) > Restrictions.Value (R)
 313       then
 314          Error_Msg_Sloc := Restrictions_Loc (R);
 315
 316          --  If we have a location for the Restrictions pragma, output it
 317
 318          if Error_Msg_Sloc > No_Location
 319            or else Error_Msg_Sloc = System_Location
 320          then
 321             if Restriction_Warnings (R) then
 322                Restriction_Msg ("|violation of restriction %#?", Rimage, N);
 323             else
 324                Restriction_Msg ("|violation of restriction %#", Rimage, N);
 325             end if;
 326
 327          --  Otherwise we have the case of an implicit restriction
 328          --  (e.g. a restriction implicitly set by another pragma)
 329
 330          else
 331             Restriction_Msg
 332               ("|violation of implicit restriction %", Rimage, N);
 333          end if;
 334       end if;
 335    end Check_Restriction;
 336
 337    -------------------------------------
 338    -- Check_Restriction_No_Dependence --
 339    -------------------------------------
 340
 341    procedure Check_Restriction_No_Dependence (U : Node_Id; Err : Node_Id) is
 342       DU : Node_Id;
 343
 344    begin
 345       for J in No_Dependence.First .. No_Dependence.Last loop
 346          DU := No_Dependence.Table (J).Unit;
 347
 348          if Same_Unit (U, DU) then
 349             Error_Msg_Sloc := Sloc (DU);
 350             Error_Msg_Node_1 := DU;
 351
 352             if No_Dependence.Table (J).Warn then
 353                Error_Msg
 354                  ("?violation of restriction `No_Dependence '='> &`#",
 355                   Sloc (Err));
 356             else
 357                Error_Msg
 358                  ("|violation of restriction `No_Dependence '='> &`#",
 359                   Sloc (Err));
 360             end if;
 361
 362             return;
 363          end if;
 364       end loop;
 365    end Check_Restriction_No_Dependence;
 366
 367    ----------------------------------------
 368    -- Cunit_Boolean_Restrictions_Restore --
 369    ----------------------------------------
 370
 371    procedure Cunit_Boolean_Restrictions_Restore
 372      (R : Save_Cunit_Boolean_Restrictions)
 373    is
 374    begin
 375       for J in Cunit_Boolean_Restrictions loop
 376          Restrictions.Set (J) := R (J);
 377       end loop;
 378    end Cunit_Boolean_Restrictions_Restore;
 379
 380    -------------------------------------
 381    -- Cunit_Boolean_Restrictions_Save --
 382    -------------------------------------
 383
 384    function Cunit_Boolean_Restrictions_Save
 385      return Save_Cunit_Boolean_Restrictions
 386    is
 387       R : Save_Cunit_Boolean_Restrictions;
 388
 389    begin
 390       for J in Cunit_Boolean_Restrictions loop
 391          R (J) := Restrictions.Set (J);
 392          Restrictions.Set (J) := False;
 393       end loop;
 394
 395       return R;
 396    end Cunit_Boolean_Restrictions_Save;
 397
 398    ------------------------
 399    -- Get_Restriction_Id --
 400    ------------------------
 401
 402    function Get_Restriction_Id
 403      (N : Name_Id) return Restriction_Id
 404    is
 405    begin
 406       Get_Name_String (N);
 407       Set_Casing (All_Upper_Case);
 408
 409       for J in All_Restrictions loop
 410          declare
 411             S : constant String := Restriction_Id'Image (J);
 412          begin
 413             if S = Name_Buffer (1 .. Name_Len) then
 414                return J;
 415             end if;
 416          end;
 417       end loop;
 418
 419       return Not_A_Restriction_Id;
 420    end Get_Restriction_Id;
 421
 422    -------------------------------
 423    -- No_Exception_Handlers_Set --
 424    -------------------------------
 425
 426    function No_Exception_Handlers_Set return Boolean is
 427    begin
 428       return (No_Run_Time_Mode or else Configurable_Run_Time_Mode)
 429         and then (Restrictions.Set (No_Exception_Handlers)
 430                     or else
 431                   Restrictions.Set (No_Exception_Propagation));
 432    end No_Exception_Handlers_Set;
 433
 434    ----------------------------------
 435    -- Process_Restriction_Synonyms --
 436    ----------------------------------
 437
 438    --  Note: body of this function must be coordinated with list of
 439    --  renaming declarations in System.Rident.
 440
 441    function Process_Restriction_Synonyms (N : Node_Id) return Name_Id
 442    is
 443       Old_Name : constant Name_Id := Chars (N);
 444       New_Name : Name_Id;
 445
 446    begin
 447       case Old_Name is
 448          when Name_Boolean_Entry_Barriers =>
 449             New_Name := Name_Simple_Barriers;
 450
 451          when Name_Max_Entry_Queue_Depth =>
 452             New_Name := Name_Max_Entry_Queue_Length;
 453
 454          when Name_No_Dynamic_Interrupts =>
 455             New_Name := Name_No_Dynamic_Attachment;
 456
 457          when Name_No_Requeue =>
 458             New_Name := Name_No_Requeue_Statements;
 459
 460          when Name_No_Task_Attributes =>
 461             New_Name := Name_No_Task_Attributes_Package;
 462
 463          when others =>
 464             return Old_Name;
 465       end case;
 466
 467       if Warn_On_Obsolescent_Feature then
 468          Error_Msg_Name_1 := Old_Name;
 469          Error_Msg_N ("restriction identifier % is obsolescent?", N);
 470          Error_Msg_Name_1 := New_Name;
 471          Error_Msg_N ("|use restriction identifier % instead", N);
 472       end if;
 473
 474       return New_Name;
 475    end Process_Restriction_Synonyms;
 476
 477    ------------------------
 478    -- Restricted_Profile --
 479    ------------------------
 480
 481    function Restricted_Profile return Boolean is
 482    begin
 483       if Restricted_Profile_Cached then
 484          return Restricted_Profile_Result;
 485
 486       else
 487          Restricted_Profile_Result := True;
 488          Restricted_Profile_Cached := True;
 489
 490          declare
 491             R : Restriction_Flags  renames Profile_Info (Restricted).Set;
 492             V : Restriction_Values renames Profile_Info (Restricted).Value;
 493          begin
 494             for J in R'Range loop
 495                if R (J)
 496                  and then (Restrictions.Set (J) = False
 497                              or else Restriction_Warnings (J)
 498                              or else
 499                                (J in All_Parameter_Restrictions
 500                                   and then Restrictions.Value (J) > V (J)))
 501                then
 502                   Restricted_Profile_Result := False;
 503                   exit;
 504                end if;
 505             end loop;
 506
 507             return Restricted_Profile_Result;
 508          end;
 509       end if;
 510    end Restricted_Profile;
 511
 512    ------------------------
 513    -- Restriction_Active --
 514    ------------------------
 515
 516    function Restriction_Active (R : All_Restrictions) return Boolean is
 517    begin
 518       return Restrictions.Set (R) and then not Restriction_Warnings (R);
 519    end Restriction_Active;
 520
 521    ---------------------
 522    -- Restriction_Msg --
 523    ---------------------
 524
 525    procedure Restriction_Msg (Msg : String; R : String; N : Node_Id) is
 526       B : String (1 .. Msg'Length + 2 * R'Length + 1);
 527       P : Natural := 1;
 528
 529    begin
 530       Name_Buffer (1 .. R'Last) := R;
 531       Name_Len := R'Length;
 532       Set_Casing (Identifier_Casing (Get_Source_File_Index (Sloc (N))));
 533
 534       P := 0;
 535       for J in Msg'Range loop
 536          if Msg (J) = '%' then
 537             P := P + 1;
 538             B (P) := '`';
 539
 540             --  Put characters of image in message, quoting upper case letters
 541
 542             for J in 1 .. Name_Len loop
 543                if Name_Buffer (J) in 'A' .. 'Z' then
 544                   P := P + 1;
 545                   B (P) := ''';
 546                end if;
 547
 548                P := P + 1;
 549                B (P) := Name_Buffer (J);
 550             end loop;
 551
 552             P := P + 1;
 553             B (P) := '`';
 554
 555          else
 556             P := P + 1;
 557             B (P) := Msg (J);
 558          end if;
 559       end loop;
 560
 561       Error_Msg_N (B (1 .. P), N);
 562    end Restriction_Msg;
 563
 564    ---------------
 565    -- Same_Unit --
 566    ---------------
 567
 568    function Same_Unit (U1, U2 : Node_Id) return Boolean is
 569    begin
 570       if Nkind (U1) = N_Identifier then
 571          return Nkind (U2) = N_Identifier and then Chars (U1) = Chars (U2);
 572
 573       elsif Nkind (U2) = N_Identifier then
 574          return False;
 575
 576       elsif (Nkind (U1) = N_Selected_Component
 577              or else Nkind (U1) = N_Expanded_Name)
 578         and then
 579           (Nkind (U2) = N_Selected_Component
 580            or else Nkind (U2) = N_Expanded_Name)
 581       then
 582          return Same_Unit (Prefix (U1), Prefix (U2))
 583            and then Same_Unit (Selector_Name (U1), Selector_Name (U2));
 584       else
 585          return False;
 586       end if;
 587    end Same_Unit;
 588
 589    ------------------------------
 590    -- Set_Profile_Restrictions --
 591    ------------------------------
 592
 593    procedure Set_Profile_Restrictions
 594      (P    : Profile_Name;
 595       N    : Node_Id;
 596       Warn : Boolean)
 597    is
 598       R : Restriction_Flags  renames Profile_Info (P).Set;
 599       V : Restriction_Values renames Profile_Info (P).Value;
 600
 601    begin
 602       for J in R'Range loop
 603          if R (J) then
 604             declare
 605                Already_Restricted : constant Boolean := Restriction_Active (J);
 606
 607             begin
 608                --  Set the restriction
 609
 610                if J in All_Boolean_Restrictions then
 611                   Set_Restriction (J, N);
 612                else
 613                   Set_Restriction (J, N, V (J));
 614                end if;
 615
 616                --  Set warning flag, except that we do not set the warning
 617                --  flag if the restriction was already active and this is
 618                --  the warning case. That avoids a warning overriding a real
 619                --  restriction, which should never happen.
 620
 621                if not (Warn and Already_Restricted) then
 622                   Restriction_Warnings (J) := Warn;
 623                end if;
 624             end;
 625          end if;
 626       end loop;
 627    end Set_Profile_Restrictions;
 628
 629    ---------------------
 630    -- Set_Restriction --
 631    ---------------------
 632
 633    --  Case of Boolean restriction
 634
 635    procedure Set_Restriction
 636      (R : All_Boolean_Restrictions;
 637       N : Node_Id)
 638    is
 639    begin
 640       --  Restriction No_Elaboration_Code must be enforced on a unit by unit
 641       --  basis. Hence, we avoid setting the restriction when processing an
 642       --  unit which is not the main one being compiled (or its corresponding
 643       --  spec). It can happen, for example, when processing an inlined body
 644       --  (the package containing the inlined subprogram is analyzed,
 645       --  including its pragma Restrictions).
 646
 647       --  This seems like a very nasty kludge??? This is not the only per unit
 648       --  restriction why is this treated specially ???
 649
 650       if R = No_Elaboration_Code
 651         and then Current_Sem_Unit /= Main_Unit
 652         and then Cunit (Current_Sem_Unit) /= Library_Unit (Cunit (Main_Unit))
 653       then
 654          return;
 655       end if;
 656
 657       Restrictions.Set (R) := True;
 658
 659       if Restricted_Profile_Cached and Restricted_Profile_Result then
 660          null;
 661       else
 662          Restricted_Profile_Cached := False;
 663       end if;
 664
 665       --  Set location, but preserve location of system
 666       --  restriction for nice error msg with run time name
 667
 668       if Restrictions_Loc (R) /= System_Location then
 669          Restrictions_Loc (R) := Sloc (N);
 670       end if;
 671
 672       --  Record the restriction if we are in the main unit, or in the extended
 673       --  main unit. The reason that we test separately for Main_Unit is that
 674       --  gnat.adc is processed with Current_Sem_Unit = Main_Unit, but nodes in
 675       --  gnat.adc do not appear to be in the extended main source unit (they
 676       --  probably should do ???)
 677
 678       if Current_Sem_Unit = Main_Unit
 679         or else In_Extended_Main_Source_Unit (N)
 680       then
 681          if not Restriction_Warnings (R) then
 682             Main_Restrictions.Set (R) := True;
 683          end if;
 684       end if;
 685    end Set_Restriction;
 686
 687    --  Case of parameter restriction
 688
 689    procedure Set_Restriction
 690      (R : All_Parameter_Restrictions;
 691       N : Node_Id;
 692       V : Integer)
 693    is
 694    begin
 695       if Restricted_Profile_Cached and Restricted_Profile_Result then
 696          null;
 697       else
 698          Restricted_Profile_Cached := False;
 699       end if;
 700
 701       if Restrictions.Set (R) then
 702          if V < Restrictions.Value (R) then
 703             Restrictions.Value (R) := V;
 704             Restrictions_Loc (R) := Sloc (N);
 705          end if;
 706
 707       else
 708          Restrictions.Set (R) := True;
 709          Restrictions.Value (R) := V;
 710          Restrictions_Loc (R) := Sloc (N);
 711       end if;
 712
 713       --  Record the restriction if we are in the main unit,
 714       --  or in the extended main unit. The reason that we
 715       --  test separately for Main_Unit is that gnat.adc is
 716       --  processed with Current_Sem_Unit = Main_Unit, but
 717       --  nodes in gnat.adc do not appear to be the extended
 718       --  main source unit (they probably should do ???)
 719
 720       if Current_Sem_Unit = Main_Unit
 721         or else In_Extended_Main_Source_Unit (N)
 722       then
 723          if Main_Restrictions.Set (R) then
 724             if V < Main_Restrictions.Value (R) then
 725                Main_Restrictions.Value (R) := V;
 726             end if;
 727
 728          elsif not Restriction_Warnings (R) then
 729             Main_Restrictions.Set (R) := True;
 730             Main_Restrictions.Value (R) := V;
 731          end if;
 732       end if;
 733    end Set_Restriction;
 734
 735    -----------------------------------
 736    -- Set_Restriction_No_Dependence --
 737    -----------------------------------
 738
 739    procedure Set_Restriction_No_Dependence
 740      (Unit : Node_Id;
 741       Warn : Boolean)
 742    is
 743    begin
 744       --  Loop to check for duplicate entry
 745
 746       for J in No_Dependence.First .. No_Dependence.Last loop
 747
 748          --  Case of entry already in table
 749
 750          if Same_Unit (Unit, No_Dependence.Table (J).Unit) then
 751
 752             --  Error has precedence over warning
 753
 754             if not Warn then
 755                No_Dependence.Table (J).Warn := False;
 756             end if;
 757
 758             return;
 759          end if;
 760       end loop;
 761
 762       --  Entry is not currently in table
 763
 764       No_Dependence.Append ((Unit, Warn));
 765    end Set_Restriction_No_Dependence;
 766
 767    ----------------------------------
 768    -- Suppress_Restriction_Message --
 769    ----------------------------------
 770
 771    function Suppress_Restriction_Message (N : Node_Id) return Boolean is
 772    begin
 773       --  We only output messages for the extended main source unit
 774
 775       if In_Extended_Main_Source_Unit (N) then
 776          return False;
 777
 778       --  If loaded by rtsfind, then suppress message
 779
 780       elsif Sloc (N) <= No_Location then
 781          return True;
 782
 783       --  Otherwise suppress message if internal file
 784
 785       else
 786          return Is_Internal_File_Name (Unit_File_Name (Get_Source_Unit (N)));
 787       end if;
 788    end Suppress_Restriction_Message;
 789
 790    ---------------------
 791    -- Tasking_Allowed --
 792    ---------------------
 793
 794    function Tasking_Allowed return Boolean is
 795    begin
 796       return not Restrictions.Set (No_Tasking)
 797         and then (not Restrictions.Set (Max_Tasks)
 798                     or else Restrictions.Value (Max_Tasks) > 0);
 799    end Tasking_Allowed;
 800
 801 end Restrict;