gcc/ada/sem_util.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             S E M _ U T I L                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2009, 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 Checks;   use Checks;
  29 with Debug;    use Debug;
  30 with Errout;   use Errout;
  31 with Elists;   use Elists;
  32 with Exp_Ch11; use Exp_Ch11;
  33 with Exp_Disp; use Exp_Disp;
  34 with Exp_Tss;  use Exp_Tss;
  35 with Exp_Util; use Exp_Util;
  36 with Fname;    use Fname;
  37 with Freeze;   use Freeze;
  38 with Lib;      use Lib;
  39 with Lib.Xref; use Lib.Xref;
  40 with Nlists;   use Nlists;
  41 with Output;   use Output;
  42 with Opt;      use Opt;
  43 with Rtsfind;  use Rtsfind;
  44 with Scans;    use Scans;
  45 with Scn;      use Scn;
  46 with Sem;      use Sem;
  47 with Sem_Aux;  use Sem_Aux;
  48 with Sem_Attr; use Sem_Attr;
  49 with Sem_Ch8;  use Sem_Ch8;
  50 with Sem_Disp; use Sem_Disp;
  51 with Sem_Eval; use Sem_Eval;
  52 with Sem_Res;  use Sem_Res;
  53 with Sem_SCIL; use Sem_SCIL;
  54 with Sem_Type; use Sem_Type;
  55 with Sinfo;    use Sinfo;
  56 with Sinput;   use Sinput;
  57 with Stand;    use Stand;
  58 with Style;
  59 with Stringt;  use Stringt;
  60 with Targparm; use Targparm;
  61 with Tbuild;   use Tbuild;
  62 with Ttypes;   use Ttypes;
  63 with Uname;    use Uname;
  64
  65 with GNAT.HTable; use GNAT.HTable;
  66 package body Sem_Util is
  67
  68    ----------------------------------------
  69    -- Global_Variables for New_Copy_Tree --
  70    ----------------------------------------
  71
  72    --  These global variables are used by New_Copy_Tree. See description
  73    --  of the body of this subprogram for details. Global variables can be
  74    --  safely used by New_Copy_Tree, since there is no case of a recursive
  75    --  call from the processing inside New_Copy_Tree.
  76
  77    NCT_Hash_Threshhold : constant := 20;
  78    --  If there are more than this number of pairs of entries in the
  79    --  map, then Hash_Tables_Used will be set, and the hash tables will
  80    --  be initialized and used for the searches.
  81
  82    NCT_Hash_Tables_Used : Boolean := False;
  83    --  Set to True if hash tables are in use
  84
  85    NCT_Table_Entries : Nat;
  86    --  Count entries in table to see if threshhold is reached
  87
  88    NCT_Hash_Table_Setup : Boolean := False;
  89    --  Set to True if hash table contains data. We set this True if we
  90    --  setup the hash table with data, and leave it set permanently
  91    --  from then on, this is a signal that second and subsequent users
  92    --  of the hash table must clear the old entries before reuse.
  93
  94    subtype NCT_Header_Num is Int range 0 .. 511;
  95    --  Defines range of headers in hash tables (512 headers)
  96
  97    -----------------------
  98    -- Local Subprograms --
  99    -----------------------
 100
 101    function Build_Component_Subtype
 102      (C   : List_Id;
 103       Loc : Source_Ptr;
 104       T   : Entity_Id) return Node_Id;
 105    --  This function builds the subtype for Build_Actual_Subtype_Of_Component
 106    --  and Build_Discriminal_Subtype_Of_Component. C is a list of constraints,
 107    --  Loc is the source location, T is the original subtype.
 108
 109    function Is_Fully_Initialized_Variant (Typ : Entity_Id) return Boolean;
 110    --  Subsidiary to Is_Fully_Initialized_Type. For an unconstrained type
 111    --  with discriminants whose default values are static, examine only the
 112    --  components in the selected variant to determine whether all of them
 113    --  have a default.
 114
 115    function Has_Null_Extension (T : Entity_Id) return Boolean;
 116    --  T is a derived tagged type. Check whether the type extension is null.
 117    --  If the parent type is fully initialized, T can be treated as such.
 118
 119    ------------------------------
 120    --  Abstract_Interface_List --
 121    ------------------------------
 122
 123    function Abstract_Interface_List (Typ : Entity_Id) return List_Id is
 124       Nod : Node_Id;
 125
 126    begin
 127       if Is_Concurrent_Type (Typ) then
 128
 129          --  If we are dealing with a synchronized subtype, go to the base
 130          --  type, whose declaration has the interface list.
 131
 132          --  Shouldn't this be Declaration_Node???
 133
 134          Nod := Parent (Base_Type (Typ));
 135
 136          if Nkind (Nod) = N_Full_Type_Declaration then
 137             return Empty_List;
 138          end if;
 139
 140       elsif Ekind (Typ) = E_Record_Type_With_Private then
 141          if Nkind (Parent (Typ)) = N_Full_Type_Declaration then
 142             Nod := Type_Definition (Parent (Typ));
 143
 144          elsif Nkind (Parent (Typ)) = N_Private_Type_Declaration then
 145             if Present (Full_View (Typ)) then
 146                Nod := Type_Definition (Parent (Full_View (Typ)));
 147
 148             --  If the full-view is not available we cannot do anything else
 149             --  here (the source has errors).
 150
 151             else
 152                return Empty_List;
 153             end if;
 154
 155          --  Support for generic formals with interfaces is still missing ???
 156
 157          elsif Nkind (Parent (Typ)) = N_Formal_Type_Declaration then
 158             return Empty_List;
 159
 160          else
 161             pragma Assert
 162               (Nkind (Parent (Typ)) = N_Private_Extension_Declaration);
 163             Nod := Parent (Typ);
 164          end if;
 165
 166       elsif Ekind (Typ) = E_Record_Subtype then
 167          Nod := Type_Definition (Parent (Etype (Typ)));
 168
 169       elsif Ekind (Typ) = E_Record_Subtype_With_Private then
 170
 171          --  Recurse, because parent may still be a private extension. Also
 172          --  note that the full view of the subtype or the full view of its
 173          --  base type may (both) be unavailable.
 174
 175          return Abstract_Interface_List (Etype (Typ));
 176
 177       else pragma Assert ((Ekind (Typ)) = E_Record_Type);
 178          if Nkind (Parent (Typ)) = N_Formal_Type_Declaration then
 179             Nod := Formal_Type_Definition (Parent (Typ));
 180          else
 181             Nod := Type_Definition (Parent (Typ));
 182          end if;
 183       end if;
 184
 185       return Interface_List (Nod);
 186    end Abstract_Interface_List;
 187
 188    --------------------------------
 189    -- Add_Access_Type_To_Process --
 190    --------------------------------
 191
 192    procedure Add_Access_Type_To_Process (E : Entity_Id; A : Entity_Id) is
 193       L : Elist_Id;
 194
 195    begin
 196       Ensure_Freeze_Node (E);
 197       L := Access_Types_To_Process (Freeze_Node (E));
 198
 199       if No (L) then
 200          L := New_Elmt_List;
 201          Set_Access_Types_To_Process (Freeze_Node (E), L);
 202       end if;
 203
 204       Append_Elmt (A, L);
 205    end Add_Access_Type_To_Process;
 206
 207    ----------------------------
 208    -- Add_Global_Declaration --
 209    ----------------------------
 210
 211    procedure Add_Global_Declaration (N : Node_Id) is
 212       Aux_Node : constant Node_Id := Aux_Decls_Node (Cunit (Current_Sem_Unit));
 213
 214    begin
 215       if No (Declarations (Aux_Node)) then
 216          Set_Declarations (Aux_Node, New_List);
 217       end if;
 218
 219       Append_To (Declarations (Aux_Node), N);
 220       Analyze (N);
 221    end Add_Global_Declaration;
 222
 223    -----------------------
 224    -- Alignment_In_Bits --
 225    -----------------------
 226
 227    function Alignment_In_Bits (E : Entity_Id) return Uint is
 228    begin
 229       return Alignment (E) * System_Storage_Unit;
 230    end Alignment_In_Bits;
 231
 232    -----------------------------------------
 233    -- Apply_Compile_Time_Constraint_Error --
 234    -----------------------------------------
 235
 236    procedure Apply_Compile_Time_Constraint_Error
 237      (N      : Node_Id;
 238       Msg    : String;
 239       Reason : RT_Exception_Code;
 240       Ent    : Entity_Id  := Empty;
 241       Typ    : Entity_Id  := Empty;
 242       Loc    : Source_Ptr := No_Location;
 243       Rep    : Boolean    := True;
 244       Warn   : Boolean    := False)
 245    is
 246       Stat   : constant Boolean := Is_Static_Expression (N);
 247       R_Stat : constant Node_Id :=
 248                  Make_Raise_Constraint_Error (Sloc (N), Reason => Reason);
 249       Rtyp   : Entity_Id;
 250
 251    begin
 252       if No (Typ) then
 253          Rtyp := Etype (N);
 254       else
 255          Rtyp := Typ;
 256       end if;
 257
 258       Discard_Node
 259         (Compile_Time_Constraint_Error (N, Msg, Ent, Loc, Warn => Warn));
 260
 261       if not Rep then
 262          return;
 263       end if;
 264
 265       --  Now we replace the node by an N_Raise_Constraint_Error node
 266       --  This does not need reanalyzing, so set it as analyzed now.
 267
 268       Rewrite (N, R_Stat);
 269       Set_Analyzed (N, True);
 270
 271       Set_Etype (N, Rtyp);
 272       Set_Raises_Constraint_Error (N);
 273
 274       --  Now deal with possible local raise handling
 275
 276       Possible_Local_Raise (N, Standard_Constraint_Error);
 277
 278       --  If the original expression was marked as static, the result is
 279       --  still marked as static, but the Raises_Constraint_Error flag is
 280       --  always set so that further static evaluation is not attempted.
 281
 282       if Stat then
 283          Set_Is_Static_Expression (N);
 284       end if;
 285    end Apply_Compile_Time_Constraint_Error;
 286
 287    --------------------------
 288    -- Build_Actual_Subtype --
 289    --------------------------
 290
 291    function Build_Actual_Subtype
 292      (T : Entity_Id;
 293       N : Node_Or_Entity_Id) return Node_Id
 294    is
 295       Loc : Source_Ptr;
 296       --  Normally Sloc (N), but may point to corresponding body in some cases
 297
 298       Constraints : List_Id;
 299       Decl        : Node_Id;
 300       Discr       : Entity_Id;
 301       Hi          : Node_Id;
 302       Lo          : Node_Id;
 303       Subt        : Entity_Id;
 304       Disc_Type   : Entity_Id;
 305       Obj         : Node_Id;
 306
 307    begin
 308       Loc := Sloc (N);
 309
 310       if Nkind (N) = N_Defining_Identifier then
 311          Obj := New_Reference_To (N, Loc);
 312
 313          --  If this is a formal parameter of a subprogram declaration, and
 314          --  we are compiling the body, we want the declaration for the
 315          --  actual subtype to carry the source position of the body, to
 316          --  prevent anomalies in gdb when stepping through the code.
 317
 318          if Is_Formal (N) then
 319             declare
 320                Decl : constant Node_Id := Unit_Declaration_Node (Scope (N));
 321             begin
 322                if Nkind (Decl) = N_Subprogram_Declaration
 323                  and then Present (Corresponding_Body (Decl))
 324                then
 325                   Loc := Sloc (Corresponding_Body (Decl));
 326                end if;
 327             end;
 328          end if;
 329
 330       else
 331          Obj := N;
 332       end if;
 333
 334       if Is_Array_Type (T) then
 335          Constraints := New_List;
 336          for J in 1 .. Number_Dimensions (T) loop
 337
 338             --  Build an array subtype declaration with the nominal subtype and
 339             --  the bounds of the actual. Add the declaration in front of the
 340             --  local declarations for the subprogram, for analysis before any
 341             --  reference to the formal in the body.
 342
 343             Lo :=
 344               Make_Attribute_Reference (Loc,
 345                 Prefix         =>
 346                   Duplicate_Subexpr_No_Checks (Obj, Name_Req => True),
 347                 Attribute_Name => Name_First,
 348                 Expressions    => New_List (
 349                   Make_Integer_Literal (Loc, J)));
 350
 351             Hi :=
 352               Make_Attribute_Reference (Loc,
 353                 Prefix         =>
 354                   Duplicate_Subexpr_No_Checks (Obj, Name_Req => True),
 355                 Attribute_Name => Name_Last,
 356                 Expressions    => New_List (
 357                   Make_Integer_Literal (Loc, J)));
 358
 359             Append (Make_Range (Loc, Lo, Hi), Constraints);
 360          end loop;
 361
 362       --  If the type has unknown discriminants there is no constrained
 363       --  subtype to build. This is never called for a formal or for a
 364       --  lhs, so returning the type is ok ???
 365
 366       elsif Has_Unknown_Discriminants (T) then
 367          return T;
 368
 369       else
 370          Constraints := New_List;
 371
 372          --  Type T is a generic derived type, inherit the discriminants from
 373          --  the parent type.
 374
 375          if Is_Private_Type (T)
 376            and then No (Full_View (T))
 377
 378             --  T was flagged as an error if it was declared as a formal
 379             --  derived type with known discriminants. In this case there
 380             --  is no need to look at the parent type since T already carries
 381             --  its own discriminants.
 382
 383            and then not Error_Posted (T)
 384          then
 385             Disc_Type := Etype (Base_Type (T));
 386          else
 387             Disc_Type := T;
 388          end if;
 389
 390          Discr := First_Discriminant (Disc_Type);
 391          while Present (Discr) loop
 392             Append_To (Constraints,
 393               Make_Selected_Component (Loc,
 394                 Prefix =>
 395                   Duplicate_Subexpr_No_Checks (Obj),
 396                 Selector_Name => New_Occurrence_Of (Discr, Loc)));
 397             Next_Discriminant (Discr);
 398          end loop;
 399       end if;
 400
 401       Subt :=
 402         Make_Defining_Identifier (Loc,
 403           Chars => New_Internal_Name ('S'));
 404       Set_Is_Internal (Subt);
 405
 406       Decl :=
 407         Make_Subtype_Declaration (Loc,
 408           Defining_Identifier => Subt,
 409           Subtype_Indication =>
 410             Make_Subtype_Indication (Loc,
 411               Subtype_Mark => New_Reference_To (T,  Loc),
 412               Constraint  =>
 413                 Make_Index_Or_Discriminant_Constraint (Loc,
 414                   Constraints => Constraints)));
 415
 416       Mark_Rewrite_Insertion (Decl);
 417       return Decl;
 418    end Build_Actual_Subtype;
 419
 420    ---------------------------------------
 421    -- Build_Actual_Subtype_Of_Component --
 422    ---------------------------------------
 423
 424    function Build_Actual_Subtype_Of_Component
 425      (T : Entity_Id;
 426       N : Node_Id) return Node_Id
 427    is
 428       Loc       : constant Source_Ptr := Sloc (N);
 429       P         : constant Node_Id    := Prefix (N);
 430       D         : Elmt_Id;
 431       Id        : Node_Id;
 432       Indx_Type : Entity_Id;
 433
 434       Deaccessed_T : Entity_Id;
 435       --  This is either a copy of T, or if T is an access type, then it is
 436       --  the directly designated type of this access type.
 437
 438       function Build_Actual_Array_Constraint return List_Id;
 439       --  If one or more of the bounds of the component depends on
 440       --  discriminants, build  actual constraint using the discriminants
 441       --  of the prefix.
 442
 443       function Build_Actual_Record_Constraint return List_Id;
 444       --  Similar to previous one, for discriminated components constrained
 445       --  by the discriminant of the enclosing object.
 446
 447       -----------------------------------
 448       -- Build_Actual_Array_Constraint --
 449       -----------------------------------
 450
 451       function Build_Actual_Array_Constraint return List_Id is
 452          Constraints : constant List_Id := New_List;
 453          Indx        : Node_Id;
 454          Hi          : Node_Id;
 455          Lo          : Node_Id;
 456          Old_Hi      : Node_Id;
 457          Old_Lo      : Node_Id;
 458
 459       begin
 460          Indx := First_Index (Deaccessed_T);
 461          while Present (Indx) loop
 462             Old_Lo := Type_Low_Bound  (Etype (Indx));
 463             Old_Hi := Type_High_Bound (Etype (Indx));
 464
 465             if Denotes_Discriminant (Old_Lo) then
 466                Lo :=
 467                  Make_Selected_Component (Loc,
 468                    Prefix => New_Copy_Tree (P),
 469                    Selector_Name => New_Occurrence_Of (Entity (Old_Lo), Loc));
 470
 471             else
 472                Lo := New_Copy_Tree (Old_Lo);
 473
 474                --  The new bound will be reanalyzed in the enclosing
 475                --  declaration. For literal bounds that come from a type
 476                --  declaration, the type of the context must be imposed, so
 477                --  insure that analysis will take place. For non-universal
 478                --  types this is not strictly necessary.
 479
 480                Set_Analyzed (Lo, False);
 481             end if;
 482
 483             if Denotes_Discriminant (Old_Hi) then
 484                Hi :=
 485                  Make_Selected_Component (Loc,
 486                    Prefix => New_Copy_Tree (P),
 487                    Selector_Name => New_Occurrence_Of (Entity (Old_Hi), Loc));
 488
 489             else
 490                Hi := New_Copy_Tree (Old_Hi);
 491                Set_Analyzed (Hi, False);
 492             end if;
 493
 494             Append (Make_Range (Loc, Lo, Hi), Constraints);
 495             Next_Index (Indx);
 496          end loop;
 497
 498          return Constraints;
 499       end Build_Actual_Array_Constraint;
 500
 501       ------------------------------------
 502       -- Build_Actual_Record_Constraint --
 503       ------------------------------------
 504
 505       function Build_Actual_Record_Constraint return List_Id is
 506          Constraints : constant List_Id := New_List;
 507          D           : Elmt_Id;
 508          D_Val       : Node_Id;
 509
 510       begin
 511          D := First_Elmt (Discriminant_Constraint (Deaccessed_T));
 512          while Present (D) loop
 513             if Denotes_Discriminant (Node (D)) then
 514                D_Val :=  Make_Selected_Component (Loc,
 515                  Prefix => New_Copy_Tree (P),
 516                 Selector_Name => New_Occurrence_Of (Entity (Node (D)), Loc));
 517
 518             else
 519                D_Val := New_Copy_Tree (Node (D));
 520             end if;
 521
 522             Append (D_Val, Constraints);
 523             Next_Elmt (D);
 524          end loop;
 525
 526          return Constraints;
 527       end Build_Actual_Record_Constraint;
 528
 529    --  Start of processing for Build_Actual_Subtype_Of_Component
 530
 531    begin
 532       --  Why the test for Spec_Expression mode here???
 533
 534       if In_Spec_Expression then
 535          return Empty;
 536
 537       --  More comments for the rest of this body would be good ???
 538
 539       elsif Nkind (N) = N_Explicit_Dereference then
 540          if Is_Composite_Type (T)
 541            and then not Is_Constrained (T)
 542            and then not (Is_Class_Wide_Type (T)
 543                           and then Is_Constrained (Root_Type (T)))
 544            and then not Has_Unknown_Discriminants (T)
 545          then
 546             --  If the type of the dereference is already constrained, it is an
 547             --  actual subtype.
 548
 549             if Is_Array_Type (Etype (N))
 550               and then Is_Constrained (Etype (N))
 551             then
 552                return Empty;
 553             else
 554                Remove_Side_Effects (P);
 555                return Build_Actual_Subtype (T, N);
 556             end if;
 557          else
 558             return Empty;
 559          end if;
 560       end if;
 561
 562       if Ekind (T) = E_Access_Subtype then
 563          Deaccessed_T := Designated_Type (T);
 564       else
 565          Deaccessed_T := T;
 566       end if;
 567
 568       if Ekind (Deaccessed_T) = E_Array_Subtype then
 569          Id := First_Index (Deaccessed_T);
 570          while Present (Id) loop
 571             Indx_Type := Underlying_Type (Etype (Id));
 572
 573             if Denotes_Discriminant (Type_Low_Bound  (Indx_Type))
 574                  or else
 575                Denotes_Discriminant (Type_High_Bound (Indx_Type))
 576             then
 577                Remove_Side_Effects (P);
 578                return
 579                  Build_Component_Subtype
 580                    (Build_Actual_Array_Constraint, Loc, Base_Type (T));
 581             end if;
 582
 583             Next_Index (Id);
 584          end loop;
 585
 586       elsif Is_Composite_Type (Deaccessed_T)
 587         and then Has_Discriminants (Deaccessed_T)
 588         and then not Has_Unknown_Discriminants (Deaccessed_T)
 589       then
 590          D := First_Elmt (Discriminant_Constraint (Deaccessed_T));
 591          while Present (D) loop
 592             if Denotes_Discriminant (Node (D)) then
 593                Remove_Side_Effects (P);
 594                return
 595                  Build_Component_Subtype (
 596                    Build_Actual_Record_Constraint, Loc, Base_Type (T));
 597             end if;
 598
 599             Next_Elmt (D);
 600          end loop;
 601       end if;
 602
 603       --  If none of the above, the actual and nominal subtypes are the same
 604
 605       return Empty;
 606    end Build_Actual_Subtype_Of_Component;
 607
 608    -----------------------------
 609    -- Build_Component_Subtype --
 610    -----------------------------
 611
 612    function Build_Component_Subtype
 613      (C   : List_Id;
 614       Loc : Source_Ptr;
 615       T   : Entity_Id) return Node_Id
 616    is
 617       Subt : Entity_Id;
 618       Decl : Node_Id;
 619
 620    begin
 621       --  Unchecked_Union components do not require component subtypes
 622
 623       if Is_Unchecked_Union (T) then
 624          return Empty;
 625       end if;
 626
 627       Subt :=
 628         Make_Defining_Identifier (Loc,
 629           Chars => New_Internal_Name ('S'));
 630       Set_Is_Internal (Subt);
 631
 632       Decl :=
 633         Make_Subtype_Declaration (Loc,
 634           Defining_Identifier => Subt,
 635           Subtype_Indication =>
 636             Make_Subtype_Indication (Loc,
 637               Subtype_Mark => New_Reference_To (Base_Type (T),  Loc),
 638               Constraint  =>
 639                 Make_Index_Or_Discriminant_Constraint (Loc,
 640                   Constraints => C)));
 641
 642       Mark_Rewrite_Insertion (Decl);
 643       return Decl;
 644    end Build_Component_Subtype;
 645
 646    ---------------------------
 647    -- Build_Default_Subtype --
 648    ---------------------------
 649
 650    function Build_Default_Subtype
 651      (T : Entity_Id;
 652       N : Node_Id) return Entity_Id
 653    is
 654       Loc  : constant Source_Ptr := Sloc (N);
 655       Disc : Entity_Id;
 656
 657    begin
 658       if not Has_Discriminants (T) or else Is_Constrained (T) then
 659          return T;
 660       end if;
 661
 662       Disc := First_Discriminant (T);
 663
 664       if No (Discriminant_Default_Value (Disc)) then
 665          return T;
 666       end if;
 667
 668       declare
 669          Act : constant Entity_Id :=
 670                  Make_Defining_Identifier (Loc,
 671                    Chars => New_Internal_Name ('S'));
 672
 673          Constraints : constant List_Id := New_List;
 674          Decl        : Node_Id;
 675
 676       begin
 677          while Present (Disc) loop
 678             Append_To (Constraints,
 679               New_Copy_Tree (Discriminant_Default_Value (Disc)));
 680             Next_Discriminant (Disc);
 681          end loop;
 682
 683          Decl :=
 684            Make_Subtype_Declaration (Loc,
 685              Defining_Identifier => Act,
 686              Subtype_Indication =>
 687                Make_Subtype_Indication (Loc,
 688                  Subtype_Mark => New_Occurrence_Of (T, Loc),
 689                  Constraint =>
 690                    Make_Index_Or_Discriminant_Constraint (Loc,
 691                      Constraints => Constraints)));
 692
 693          Insert_Action (N, Decl);
 694          Analyze (Decl);
 695          return Act;
 696       end;
 697    end Build_Default_Subtype;
 698
 699    --------------------------------------------
 700    -- Build_Discriminal_Subtype_Of_Component --
 701    --------------------------------------------
 702
 703    function Build_Discriminal_Subtype_Of_Component
 704      (T : Entity_Id) return Node_Id
 705    is
 706       Loc : constant Source_Ptr := Sloc (T);
 707       D   : Elmt_Id;
 708       Id  : Node_Id;
 709
 710       function Build_Discriminal_Array_Constraint return List_Id;
 711       --  If one or more of the bounds of the component depends on
 712       --  discriminants, build  actual constraint using the discriminants
 713       --  of the prefix.
 714
 715       function Build_Discriminal_Record_Constraint return List_Id;
 716       --  Similar to previous one, for discriminated components constrained
 717       --  by the discriminant of the enclosing object.
 718
 719       ----------------------------------------
 720       -- Build_Discriminal_Array_Constraint --
 721       ----------------------------------------
 722
 723       function Build_Discriminal_Array_Constraint return List_Id is
 724          Constraints : constant List_Id := New_List;
 725          Indx        : Node_Id;
 726          Hi          : Node_Id;
 727          Lo          : Node_Id;
 728          Old_Hi      : Node_Id;
 729          Old_Lo      : Node_Id;
 730
 731       begin
 732          Indx := First_Index (T);
 733          while Present (Indx) loop
 734             Old_Lo := Type_Low_Bound  (Etype (Indx));
 735             Old_Hi := Type_High_Bound (Etype (Indx));
 736
 737             if Denotes_Discriminant (Old_Lo) then
 738                Lo := New_Occurrence_Of (Discriminal (Entity (Old_Lo)), Loc);
 739
 740             else
 741                Lo := New_Copy_Tree (Old_Lo);
 742             end if;
 743
 744             if Denotes_Discriminant (Old_Hi) then
 745                Hi := New_Occurrence_Of (Discriminal (Entity (Old_Hi)), Loc);
 746
 747             else
 748                Hi := New_Copy_Tree (Old_Hi);
 749             end if;
 750
 751             Append (Make_Range (Loc, Lo, Hi), Constraints);
 752             Next_Index (Indx);
 753          end loop;
 754
 755          return Constraints;
 756       end Build_Discriminal_Array_Constraint;
 757
 758       -----------------------------------------
 759       -- Build_Discriminal_Record_Constraint --
 760       -----------------------------------------
 761
 762       function Build_Discriminal_Record_Constraint return List_Id is
 763          Constraints : constant List_Id := New_List;
 764          D           : Elmt_Id;
 765          D_Val       : Node_Id;
 766
 767       begin
 768          D := First_Elmt (Discriminant_Constraint (T));
 769          while Present (D) loop
 770             if Denotes_Discriminant (Node (D)) then
 771                D_Val :=
 772                  New_Occurrence_Of (Discriminal (Entity (Node (D))), Loc);
 773
 774             else
 775                D_Val := New_Copy_Tree (Node (D));
 776             end if;
 777
 778             Append (D_Val, Constraints);
 779             Next_Elmt (D);
 780          end loop;
 781
 782          return Constraints;
 783       end Build_Discriminal_Record_Constraint;
 784
 785    --  Start of processing for Build_Discriminal_Subtype_Of_Component
 786
 787    begin
 788       if Ekind (T) = E_Array_Subtype then
 789          Id := First_Index (T);
 790          while Present (Id) loop
 791             if Denotes_Discriminant (Type_Low_Bound  (Etype (Id))) or else
 792                Denotes_Discriminant (Type_High_Bound (Etype (Id)))
 793             then
 794                return Build_Component_Subtype
 795                  (Build_Discriminal_Array_Constraint, Loc, T);
 796             end if;
 797
 798             Next_Index (Id);
 799          end loop;
 800
 801       elsif Ekind (T) = E_Record_Subtype
 802         and then Has_Discriminants (T)
 803         and then not Has_Unknown_Discriminants (T)
 804       then
 805          D := First_Elmt (Discriminant_Constraint (T));
 806          while Present (D) loop
 807             if Denotes_Discriminant (Node (D)) then
 808                return Build_Component_Subtype
 809                  (Build_Discriminal_Record_Constraint, Loc, T);
 810             end if;
 811
 812             Next_Elmt (D);
 813          end loop;
 814       end if;
 815
 816       --  If none of the above, the actual and nominal subtypes are the same
 817
 818       return Empty;
 819    end Build_Discriminal_Subtype_Of_Component;
 820
 821    ------------------------------
 822    -- Build_Elaboration_Entity --
 823    ------------------------------
 824
 825    procedure Build_Elaboration_Entity (N : Node_Id; Spec_Id : Entity_Id) is
 826       Loc      : constant Source_Ptr := Sloc (N);
 827       Decl     : Node_Id;
 828       Elab_Ent : Entity_Id;
 829
 830       procedure Set_Package_Name (Ent : Entity_Id);
 831       --  Given an entity, sets the fully qualified name of the entity in
 832       --  Name_Buffer, with components separated by double underscores. This
 833       --  is a recursive routine that climbs the scope chain to Standard.
 834
 835       ----------------------
 836       -- Set_Package_Name --
 837       ----------------------
 838
 839       procedure Set_Package_Name (Ent : Entity_Id) is
 840       begin
 841          if Scope (Ent) /= Standard_Standard then
 842             Set_Package_Name (Scope (Ent));
 843
 844             declare
 845                Nam : constant String := Get_Name_String (Chars (Ent));
 846             begin
 847                Name_Buffer (Name_Len + 1) := '_';
 848                Name_Buffer (Name_Len + 2) := '_';
 849                Name_Buffer (Name_Len + 3 .. Name_Len + Nam'Length + 2) := Nam;
 850                Name_Len := Name_Len + Nam'Length + 2;
 851             end;
 852
 853          else
 854             Get_Name_String (Chars (Ent));
 855          end if;
 856       end Set_Package_Name;
 857
 858    --  Start of processing for Build_Elaboration_Entity
 859
 860    begin
 861       --  Ignore if already constructed
 862
 863       if Present (Elaboration_Entity (Spec_Id)) then
 864          return;
 865       end if;
 866
 867       --  Construct name of elaboration entity as xxx_E, where xxx is the unit
 868       --  name with dots replaced by double underscore. We have to manually
 869       --  construct this name, since it will be elaborated in the outer scope,
 870       --  and thus will not have the unit name automatically prepended.
 871
 872       Set_Package_Name (Spec_Id);
 873
 874       --  Append _E
 875
 876       Name_Buffer (Name_Len + 1) := '_';
 877       Name_Buffer (Name_Len + 2) := 'E';
 878       Name_Len := Name_Len + 2;
 879
 880       --  Create elaboration flag
 881
 882       Elab_Ent :=
 883         Make_Defining_Identifier (Loc, Chars => Name_Find);
 884       Set_Elaboration_Entity (Spec_Id, Elab_Ent);
 885
 886       Decl :=
 887          Make_Object_Declaration (Loc,
 888            Defining_Identifier => Elab_Ent,
 889            Object_Definition   =>
 890              New_Occurrence_Of (Standard_Boolean, Loc),
 891            Expression          =>
 892              New_Occurrence_Of (Standard_False, Loc));
 893
 894       Push_Scope (Standard_Standard);
 895       Add_Global_Declaration (Decl);
 896       Pop_Scope;
 897
 898       --  Reset True_Constant indication, since we will indeed assign a value
 899       --  to the variable in the binder main. We also kill the Current_Value
 900       --  and Last_Assignment fields for the same reason.
 901
 902       Set_Is_True_Constant (Elab_Ent, False);
 903       Set_Current_Value    (Elab_Ent, Empty);
 904       Set_Last_Assignment  (Elab_Ent, Empty);
 905
 906       --  We do not want any further qualification of the name (if we did
 907       --  not do this, we would pick up the name of the generic package
 908       --  in the case of a library level generic instantiation).
 909
 910       Set_Has_Qualified_Name       (Elab_Ent);
 911       Set_Has_Fully_Qualified_Name (Elab_Ent);
 912    end Build_Elaboration_Entity;
 913
 914    -----------------------------------
 915    -- Cannot_Raise_Constraint_Error --
 916    -----------------------------------
 917
 918    function Cannot_Raise_Constraint_Error (Expr : Node_Id) return Boolean is
 919    begin
 920       if Compile_Time_Known_Value (Expr) then
 921          return True;
 922
 923       elsif Do_Range_Check (Expr) then
 924          return False;
 925
 926       elsif Raises_Constraint_Error (Expr) then
 927          return False;
 928
 929       else
 930          case Nkind (Expr) is
 931             when N_Identifier =>
 932                return True;
 933
 934             when N_Expanded_Name =>
 935                return True;
 936
 937             when N_Selected_Component =>
 938                return not Do_Discriminant_Check (Expr);
 939
 940             when N_Attribute_Reference =>
 941                if Do_Overflow_Check (Expr) then
 942                   return False;
 943
 944                elsif No (Expressions (Expr)) then
 945                   return True;
 946
 947                else
 948                   declare
 949                      N : Node_Id;
 950
 951                   begin
 952                      N := First (Expressions (Expr));
 953                      while Present (N) loop
 954                         if Cannot_Raise_Constraint_Error (N) then
 955                            Next (N);
 956                         else
 957                            return False;
 958                         end if;
 959                      end loop;
 960
 961                      return True;
 962                   end;
 963                end if;
 964
 965             when N_Type_Conversion =>
 966                if Do_Overflow_Check (Expr)
 967                  or else Do_Length_Check (Expr)
 968                  or else Do_Tag_Check (Expr)
 969                then
 970                   return False;
 971                else
 972                   return
 973                     Cannot_Raise_Constraint_Error (Expression (Expr));
 974                end if;
 975
 976             when N_Unchecked_Type_Conversion =>
 977                return Cannot_Raise_Constraint_Error (Expression (Expr));
 978
 979             when N_Unary_Op =>
 980                if Do_Overflow_Check (Expr) then
 981                   return False;
 982                else
 983                   return
 984                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
 985                end if;
 986
 987             when N_Op_Divide |
 988                  N_Op_Mod    |
 989                  N_Op_Rem
 990             =>
 991                if Do_Division_Check (Expr)
 992                  or else Do_Overflow_Check (Expr)
 993                then
 994                   return False;
 995                else
 996                   return
 997                     Cannot_Raise_Constraint_Error (Left_Opnd (Expr))
 998                       and then
 999                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
1000                end if;
1001
1002             when N_Op_Add                    |
1003                  N_Op_And                    |
1004                  N_Op_Concat                 |
1005                  N_Op_Eq                     |
1006                  N_Op_Expon                  |
1007                  N_Op_Ge                     |
1008                  N_Op_Gt                     |
1009                  N_Op_Le                     |
1010                  N_Op_Lt                     |
1011                  N_Op_Multiply               |
1012                  N_Op_Ne                     |
1013                  N_Op_Or                     |
1014                  N_Op_Rotate_Left            |
1015                  N_Op_Rotate_Right           |
1016                  N_Op_Shift_Left             |
1017                  N_Op_Shift_Right            |
1018                  N_Op_Shift_Right_Arithmetic |
1019                  N_Op_Subtract               |
1020                  N_Op_Xor
1021             =>
1022                if Do_Overflow_Check (Expr) then
1023                   return False;
1024                else
1025                   return
1026                     Cannot_Raise_Constraint_Error (Left_Opnd (Expr))
1027                       and then
1028                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
1029                end if;
1030
1031             when others =>
1032                return False;
1033          end case;
1034       end if;
1035    end Cannot_Raise_Constraint_Error;
1036
1037    -----------------------------------------
1038    -- Check_Dynamically_Tagged_Expression --
1039    -----------------------------------------
1040
1041    procedure Check_Dynamically_Tagged_Expression
1042      (Expr        : Node_Id;
1043       Typ         : Entity_Id;
1044       Related_Nod : Node_Id)
1045    is
1046    begin
1047       pragma Assert (Is_Tagged_Type (Typ));
1048
1049       --  In order to avoid spurious errors when analyzing the expanded code,
1050       --  this check is done only for nodes that come from source and for
1051       --  actuals of generic instantiations.
1052
1053       if (Comes_From_Source (Related_Nod)
1054            or else In_Generic_Actual (Expr))
1055         and then (Is_Class_Wide_Type (Etype (Expr))
1056                    or else Is_Dynamically_Tagged (Expr))
1057         and then Is_Tagged_Type (Typ)
1058         and then not Is_Class_Wide_Type (Typ)
1059       then
1060          Error_Msg_N ("dynamically tagged expression not allowed!", Expr);
1061       end if;
1062    end Check_Dynamically_Tagged_Expression;
1063
1064    --------------------------
1065    -- Check_Fully_Declared --
1066    --------------------------
1067
1068    procedure Check_Fully_Declared (T : Entity_Id; N : Node_Id) is
1069    begin
1070       if Ekind (T) = E_Incomplete_Type then
1071
1072          --  Ada 2005 (AI-50217): If the type is available through a limited
1073          --  with_clause, verify that its full view has been analyzed.
1074
1075          if From_With_Type (T)
1076            and then Present (Non_Limited_View (T))
1077            and then Ekind (Non_Limited_View (T)) /= E_Incomplete_Type
1078          then
1079             --  The non-limited view is fully declared
1080             null;
1081
1082          else
1083             Error_Msg_NE
1084               ("premature usage of incomplete}", N, First_Subtype (T));
1085          end if;
1086
1087       --  Need comments for these tests ???
1088
1089       elsif Has_Private_Component (T)
1090         and then not Is_Generic_Type (Root_Type (T))
1091         and then not In_Spec_Expression
1092       then
1093          --  Special case: if T is the anonymous type created for a single
1094          --  task or protected object, use the name of the source object.
1095
1096          if Is_Concurrent_Type (T)
1097            and then not Comes_From_Source (T)
1098            and then Nkind (N) = N_Object_Declaration
1099          then
1100             Error_Msg_NE ("type of& has incomplete component", N,
1101               Defining_Identifier (N));
1102
1103          else
1104             Error_Msg_NE
1105               ("premature usage of incomplete}", N, First_Subtype (T));
1106          end if;
1107       end if;
1108    end Check_Fully_Declared;
1109
1110    -------------------------
1111    -- Check_Nested_Access --
1112    -------------------------
1113
1114    procedure Check_Nested_Access (Ent : Entity_Id) is
1115       Scop         : constant Entity_Id := Current_Scope;
1116       Current_Subp : Entity_Id;
1117       Enclosing    : Entity_Id;
1118
1119    begin
1120       --  Currently only enabled for VM back-ends for efficiency, should we
1121       --  enable it more systematically ???
1122
1123       --  Check for Is_Imported needs commenting below ???
1124
1125       if VM_Target /= No_VM
1126         and then (Ekind (Ent) = E_Variable
1127                     or else
1128                   Ekind (Ent) = E_Constant
1129                     or else
1130                   Ekind (Ent) = E_Loop_Parameter)
1131         and then Scope (Ent) /= Empty
1132         and then not Is_Library_Level_Entity (Ent)
1133         and then not Is_Imported (Ent)
1134       then
1135          if Is_Subprogram (Scop)
1136            or else Is_Generic_Subprogram (Scop)
1137            or else Is_Entry (Scop)
1138          then
1139             Current_Subp := Scop;
1140          else
1141             Current_Subp := Current_Subprogram;
1142          end if;
1143
1144          Enclosing := Enclosing_Subprogram (Ent);
1145
1146          if Enclosing /= Empty
1147            and then Enclosing /= Current_Subp
1148          then
1149             Set_Has_Up_Level_Access (Ent, True);
1150          end if;
1151       end if;
1152    end Check_Nested_Access;
1153
1154    ------------------------------------------
1155    -- Check_Potentially_Blocking_Operation --
1156    ------------------------------------------
1157
1158    procedure Check_Potentially_Blocking_Operation (N : Node_Id) is
1159       S : Entity_Id;
1160    begin
1161       --  N is one of the potentially blocking operations listed in 9.5.1(8).
1162       --  When pragma Detect_Blocking is active, the run time will raise
1163       --  Program_Error. Here we only issue a warning, since we generally
1164       --  support the use of potentially blocking operations in the absence
1165       --  of the pragma.
1166
1167       --  Indirect blocking through a subprogram call cannot be diagnosed
1168       --  statically without interprocedural analysis, so we do not attempt
1169       --  to do it here.
1170
1171       S := Scope (Current_Scope);
1172       while Present (S) and then S /= Standard_Standard loop
1173          if Is_Protected_Type (S) then
1174             Error_Msg_N
1175               ("potentially blocking operation in protected operation?", N);
1176
1177             return;
1178          end if;
1179
1180          S := Scope (S);
1181       end loop;
1182    end Check_Potentially_Blocking_Operation;
1183
1184    ------------------------------
1185    -- Check_Unprotected_Access --
1186    ------------------------------
1187
1188    procedure Check_Unprotected_Access
1189      (Context : Node_Id;
1190       Expr    : Node_Id)
1191    is
1192       Cont_Encl_Typ : Entity_Id;
1193       Pref_Encl_Typ : Entity_Id;
1194
1195       function Enclosing_Protected_Type (Obj : Node_Id) return Entity_Id;
1196       --  Check whether Obj is a private component of a protected object.
1197       --  Return the protected type where the component resides, Empty
1198       --  otherwise.
1199
1200       function Is_Public_Operation return Boolean;
1201       --  Verify that the enclosing operation is callable from outside the
1202       --  protected object, to minimize false positives.
1203
1204       ------------------------------
1205       -- Enclosing_Protected_Type --
1206       ------------------------------
1207
1208       function Enclosing_Protected_Type (Obj : Node_Id) return Entity_Id is
1209       begin
1210          if Is_Entity_Name (Obj) then
1211             declare
1212                Ent : Entity_Id := Entity (Obj);
1213
1214             begin
1215                --  The object can be a renaming of a private component, use
1216                --  the original record component.
1217
1218                if Is_Prival (Ent) then
1219                   Ent := Prival_Link (Ent);
1220                end if;
1221
1222                if Is_Protected_Type (Scope (Ent)) then
1223                   return Scope (Ent);
1224                end if;
1225             end;
1226          end if;
1227
1228          --  For indexed and selected components, recursively check the prefix
1229
1230          if Nkind_In (Obj, N_Indexed_Component, N_Selected_Component) then
1231             return Enclosing_Protected_Type (Prefix (Obj));
1232
1233          --  The object does not denote a protected component
1234
1235          else
1236             return Empty;
1237          end if;
1238       end Enclosing_Protected_Type;
1239
1240       -------------------------
1241       -- Is_Public_Operation --
1242       -------------------------
1243
1244       function Is_Public_Operation return Boolean is
1245          S : Entity_Id;
1246          E : Entity_Id;
1247
1248       begin
1249          S := Current_Scope;
1250          while Present (S)
1251            and then S /= Pref_Encl_Typ
1252          loop
1253             if Scope (S) = Pref_Encl_Typ then
1254                E := First_Entity (Pref_Encl_Typ);
1255                while Present (E)
1256                  and then E /= First_Private_Entity (Pref_Encl_Typ)
1257                loop
1258                   if E = S then
1259                      return True;
1260                   end if;
1261                   Next_Entity (E);
1262                end loop;
1263             end if;
1264
1265             S := Scope (S);
1266          end loop;
1267
1268          return False;
1269       end Is_Public_Operation;
1270
1271    --  Start of processing for Check_Unprotected_Access
1272
1273    begin
1274       if Nkind (Expr) = N_Attribute_Reference
1275         and then Attribute_Name (Expr) = Name_Unchecked_Access
1276       then
1277          Cont_Encl_Typ := Enclosing_Protected_Type (Context);
1278          Pref_Encl_Typ := Enclosing_Protected_Type (Prefix (Expr));
1279
1280          --  Check whether we are trying to export a protected component to a
1281          --  context with an equal or lower access level.
1282
1283          if Present (Pref_Encl_Typ)
1284            and then No (Cont_Encl_Typ)
1285            and then Is_Public_Operation
1286            and then Scope_Depth (Pref_Encl_Typ) >=
1287                       Object_Access_Level (Context)
1288          then
1289             Error_Msg_N
1290               ("?possible unprotected access to protected data", Expr);
1291          end if;
1292       end if;
1293    end Check_Unprotected_Access;
1294
1295    ---------------
1296    -- Check_VMS --
1297    ---------------
1298
1299    procedure Check_VMS (Construct : Node_Id) is
1300    begin
1301       if not OpenVMS_On_Target then
1302          Error_Msg_N
1303            ("this construct is allowed only in Open'V'M'S", Construct);
1304       end if;
1305    end Check_VMS;
1306
1307    ------------------------
1308    -- Collect_Interfaces --
1309    ------------------------
1310
1311    procedure Collect_Interfaces
1312      (T               : Entity_Id;
1313       Ifaces_List     : out Elist_Id;
1314       Exclude_Parents : Boolean := False;
1315       Use_Full_View   : Boolean := True)
1316    is
1317       procedure Collect (Typ : Entity_Id);
1318       --  Subsidiary subprogram used to traverse the whole list
1319       --  of directly and indirectly implemented interfaces
1320
1321       -------------
1322       -- Collect --
1323       -------------
1324
1325       procedure Collect (Typ : Entity_Id) is
1326          Ancestor   : Entity_Id;
1327          Full_T     : Entity_Id;
1328          Id         : Node_Id;
1329          Iface      : Entity_Id;
1330
1331       begin
1332          Full_T := Typ;
1333
1334          --  Handle private types
1335
1336          if Use_Full_View
1337            and then Is_Private_Type (Typ)
1338            and then Present (Full_View (Typ))
1339          then
1340             Full_T := Full_View (Typ);
1341          end if;
1342
1343          --  Include the ancestor if we are generating the whole list of
1344          --  abstract interfaces.
1345
1346          if Etype (Full_T) /= Typ
1347
1348             --  Protect the frontend against wrong sources. For example:
1349
1350             --    package P is
1351             --      type A is tagged null record;
1352             --      type B is new A with private;
1353             --      type C is new A with private;
1354             --    private
1355             --      type B is new C with null record;
1356             --      type C is new B with null record;
1357             --    end P;
1358
1359            and then Etype (Full_T) /= T
1360          then
1361             Ancestor := Etype (Full_T);
1362             Collect (Ancestor);
1363
1364             if Is_Interface (Ancestor)
1365               and then not Exclude_Parents
1366             then
1367                Append_Unique_Elmt (Ancestor, Ifaces_List);
1368             end if;
1369          end if;
1370
1371          --  Traverse the graph of ancestor interfaces
1372
1373          if Is_Non_Empty_List (Abstract_Interface_List (Full_T)) then
1374             Id := First (Abstract_Interface_List (Full_T));
1375             while Present (Id) loop
1376                Iface := Etype (Id);
1377
1378                --  Protect against wrong uses. For example:
1379                --    type I is interface;
1380                --    type O is tagged null record;
1381                --    type Wrong is new I and O with null record; -- ERROR
1382
1383                if Is_Interface (Iface) then
1384                   if Exclude_Parents
1385                     and then Etype (T) /= T
1386                     and then Interface_Present_In_Ancestor (Etype (T), Iface)
1387                   then
1388                      null;
1389                   else
1390                      Collect (Iface);
1391                      Append_Unique_Elmt (Iface, Ifaces_List);
1392                   end if;
1393                end if;
1394
1395                Next (Id);
1396             end loop;
1397          end if;
1398       end Collect;
1399
1400    --  Start of processing for Collect_Interfaces
1401
1402    begin
1403       pragma Assert (Is_Tagged_Type (T) or else Is_Concurrent_Type (T));
1404       Ifaces_List := New_Elmt_List;
1405       Collect (T);
1406    end Collect_Interfaces;
1407
1408    ----------------------------------
1409    -- Collect_Interface_Components --
1410    ----------------------------------
1411
1412    procedure Collect_Interface_Components
1413      (Tagged_Type     : Entity_Id;
1414       Components_List : out Elist_Id)
1415    is
1416       procedure Collect (Typ : Entity_Id);
1417       --  Subsidiary subprogram used to climb to the parents
1418
1419       -------------
1420       -- Collect --
1421       -------------
1422
1423       procedure Collect (Typ : Entity_Id) is
1424          Tag_Comp   : Entity_Id;
1425          Parent_Typ : Entity_Id;
1426
1427       begin
1428          --  Handle private types
1429
1430          if Present (Full_View (Etype (Typ))) then
1431             Parent_Typ := Full_View (Etype (Typ));
1432          else
1433             Parent_Typ := Etype (Typ);
1434          end if;
1435
1436          if Parent_Typ /= Typ
1437
1438             --  Protect the frontend against wrong sources. For example:
1439
1440             --    package P is
1441             --      type A is tagged null record;
1442             --      type B is new A with private;
1443             --      type C is new A with private;
1444             --    private
1445             --      type B is new C with null record;
1446             --      type C is new B with null record;
1447             --    end P;
1448
1449            and then Parent_Typ /= Tagged_Type
1450          then
1451             Collect (Parent_Typ);
1452          end if;
1453
1454          --  Collect the components containing tags of secondary dispatch
1455          --  tables.
1456
1457          Tag_Comp := Next_Tag_Component (First_Tag_Component (Typ));
1458          while Present (Tag_Comp) loop
1459             pragma Assert (Present (Related_Type (Tag_Comp)));
1460             Append_Elmt (Tag_Comp, Components_List);
1461
1462             Tag_Comp := Next_Tag_Component (Tag_Comp);
1463          end loop;
1464       end Collect;
1465
1466    --  Start of processing for Collect_Interface_Components
1467
1468    begin
1469       pragma Assert (Ekind (Tagged_Type) = E_Record_Type
1470         and then Is_Tagged_Type (Tagged_Type));
1471
1472       Components_List := New_Elmt_List;
1473       Collect (Tagged_Type);
1474    end Collect_Interface_Components;
1475
1476    -----------------------------
1477    -- Collect_Interfaces_Info --
1478    -----------------------------
1479
1480    procedure Collect_Interfaces_Info
1481      (T               : Entity_Id;
1482       Ifaces_List     : out Elist_Id;
1483       Components_List : out Elist_Id;
1484       Tags_List       : out Elist_Id)
1485    is
1486       Comps_List : Elist_Id;
1487       Comp_Elmt  : Elmt_Id;
1488       Comp_Iface : Entity_Id;
1489       Iface_Elmt : Elmt_Id;
1490       Iface      : Entity_Id;
1491
1492       function Search_Tag (Iface : Entity_Id) return Entity_Id;
1493       --  Search for the secondary tag associated with the interface type
1494       --  Iface that is implemented by T.
1495
1496       ----------------
1497       -- Search_Tag --
1498       ----------------
1499
1500       function Search_Tag (Iface : Entity_Id) return Entity_Id is
1501          ADT : Elmt_Id;
1502
1503       begin
1504          ADT := Next_Elmt (Next_Elmt (First_Elmt (Access_Disp_Table (T))));
1505          while Present (ADT)
1506             and then Ekind (Node (ADT)) = E_Constant
1507             and then Related_Type (Node (ADT)) /= Iface
1508          loop
1509             --  Skip the secondary dispatch tables of Iface
1510
1511             Next_Elmt (ADT);
1512             Next_Elmt (ADT);
1513             Next_Elmt (ADT);
1514             Next_Elmt (ADT);
1515          end loop;
1516
1517          pragma Assert (Ekind (Node (ADT)) = E_Constant);
1518          return Node (ADT);
1519       end Search_Tag;
1520
1521    --  Start of processing for Collect_Interfaces_Info
1522
1523    begin
1524       Collect_Interfaces (T, Ifaces_List);
1525       Collect_Interface_Components (T, Comps_List);
1526
1527       --  Search for the record component and tag associated with each
1528       --  interface type of T.
1529
1530       Components_List := New_Elmt_List;
1531       Tags_List       := New_Elmt_List;
1532
1533       Iface_Elmt := First_Elmt (Ifaces_List);
1534       while Present (Iface_Elmt) loop
1535          Iface := Node (Iface_Elmt);
1536
1537          --  Associate the primary tag component and the primary dispatch table
1538          --  with all the interfaces that are parents of T
1539
1540          if Is_Ancestor (Iface, T) then
1541             Append_Elmt (First_Tag_Component (T), Components_List);
1542             Append_Elmt (Node (First_Elmt (Access_Disp_Table (T))), Tags_List);
1543
1544          --  Otherwise search for the tag component and secondary dispatch
1545          --  table of Iface
1546
1547          else
1548             Comp_Elmt := First_Elmt (Comps_List);
1549             while Present (Comp_Elmt) loop
1550                Comp_Iface := Related_Type (Node (Comp_Elmt));
1551
1552                if Comp_Iface = Iface
1553                  or else Is_Ancestor (Iface, Comp_Iface)
1554                then
1555                   Append_Elmt (Node (Comp_Elmt), Components_List);
1556                   Append_Elmt (Search_Tag (Comp_Iface), Tags_List);
1557                   exit;
1558                end if;
1559
1560                Next_Elmt (Comp_Elmt);
1561             end loop;
1562             pragma Assert (Present (Comp_Elmt));
1563          end if;
1564
1565          Next_Elmt (Iface_Elmt);
1566       end loop;
1567    end Collect_Interfaces_Info;
1568
1569    ----------------------------------
1570    -- Collect_Primitive_Operations --
1571    ----------------------------------
1572
1573    function Collect_Primitive_Operations (T : Entity_Id) return Elist_Id is
1574       B_Type         : constant Entity_Id := Base_Type (T);
1575       B_Decl         : constant Node_Id   := Original_Node (Parent (B_Type));
1576       B_Scope        : Entity_Id          := Scope (B_Type);
1577       Op_List        : Elist_Id;
1578       Formal         : Entity_Id;
1579       Is_Prim        : Boolean;
1580       Formal_Derived : Boolean := False;
1581       Id             : Entity_Id;
1582
1583    begin
1584       --  For tagged types, the primitive operations are collected as they
1585       --  are declared, and held in an explicit list which is simply returned.
1586
1587       if Is_Tagged_Type (B_Type) then
1588          return Primitive_Operations (B_Type);
1589
1590       --  An untagged generic type that is a derived type inherits the
1591       --  primitive operations of its parent type. Other formal types only
1592       --  have predefined operators, which are not explicitly represented.
1593
1594       elsif Is_Generic_Type (B_Type) then
1595          if Nkind (B_Decl) = N_Formal_Type_Declaration
1596            and then Nkind (Formal_Type_Definition (B_Decl))
1597              = N_Formal_Derived_Type_Definition
1598          then
1599             Formal_Derived := True;
1600          else
1601             return New_Elmt_List;
1602          end if;
1603       end if;
1604
1605       Op_List := New_Elmt_List;
1606
1607       if B_Scope = Standard_Standard then
1608          if B_Type = Standard_String then
1609             Append_Elmt (Standard_Op_Concat, Op_List);
1610
1611          elsif B_Type = Standard_Wide_String then
1612             Append_Elmt (Standard_Op_Concatw, Op_List);
1613
1614          else
1615             null;
1616          end if;
1617
1618       elsif (Is_Package_Or_Generic_Package (B_Scope)
1619               and then
1620                 Nkind (Parent (Declaration_Node (First_Subtype (T)))) /=
1621                                                             N_Package_Body)
1622         or else Is_Derived_Type (B_Type)
1623       then
1624          --  The primitive operations appear after the base type, except
1625          --  if the derivation happens within the private part of B_Scope
1626          --  and the type is a private type, in which case both the type
1627          --  and some primitive operations may appear before the base
1628          --  type, and the list of candidates starts after the type.
1629
1630          if In_Open_Scopes (B_Scope)
1631            and then Scope (T) = B_Scope
1632            and then In_Private_Part (B_Scope)
1633          then
1634             Id := Next_Entity (T);
1635          else
1636             Id := Next_Entity (B_Type);
1637          end if;
1638
1639          while Present (Id) loop
1640
1641             --  Note that generic formal subprograms are not
1642             --  considered to be primitive operations and thus
1643             --  are never inherited.
1644
1645             if Is_Overloadable (Id)
1646               and then Nkind (Parent (Parent (Id)))
1647                          not in N_Formal_Subprogram_Declaration
1648             then
1649                Is_Prim := False;
1650
1651                if Base_Type (Etype (Id)) = B_Type then
1652                   Is_Prim := True;
1653                else
1654                   Formal := First_Formal (Id);
1655                   while Present (Formal) loop
1656                      if Base_Type (Etype (Formal)) = B_Type then
1657                         Is_Prim := True;
1658                         exit;
1659
1660                      elsif Ekind (Etype (Formal)) = E_Anonymous_Access_Type
1661                        and then Base_Type
1662                          (Designated_Type (Etype (Formal))) = B_Type
1663                      then
1664                         Is_Prim := True;
1665                         exit;
1666                      end if;
1667
1668                      Next_Formal (Formal);
1669                   end loop;
1670                end if;
1671
1672                --  For a formal derived type, the only primitives are the
1673                --  ones inherited from the parent type. Operations appearing
1674                --  in the package declaration are not primitive for it.
1675
1676                if Is_Prim
1677                  and then (not Formal_Derived
1678                             or else Present (Alias (Id)))
1679                then
1680                   Append_Elmt (Id, Op_List);
1681                end if;
1682             end if;
1683
1684             Next_Entity (Id);
1685
1686             --  For a type declared in System, some of its operations
1687             --  may appear in  the target-specific extension to System.
1688
1689             if No (Id)
1690               and then Chars (B_Scope) = Name_System
1691               and then Scope (B_Scope) = Standard_Standard
1692               and then Present_System_Aux
1693             then
1694                B_Scope := System_Aux_Id;
1695                Id := First_Entity (System_Aux_Id);
1696             end if;
1697          end loop;
1698       end if;
1699
1700       return Op_List;
1701    end Collect_Primitive_Operations;
1702
1703    -----------------------------------
1704    -- Compile_Time_Constraint_Error --
1705    -----------------------------------
1706
1707    function Compile_Time_Constraint_Error
1708      (N    : Node_Id;
1709       Msg  : String;
1710       Ent  : Entity_Id  := Empty;
1711       Loc  : Source_Ptr := No_Location;
1712       Warn : Boolean    := False) return Node_Id
1713    is
1714       Msgc : String (1 .. Msg'Length + 2);
1715       --  Copy of message, with room for possible ? and ! at end
1716
1717       Msgl : Natural;
1718       Wmsg : Boolean;
1719       P    : Node_Id;
1720       OldP : Node_Id;
1721       Msgs : Boolean;
1722       Eloc : Source_Ptr;
1723
1724    begin
1725       --  A static constraint error in an instance body is not a fatal error.
1726       --  we choose to inhibit the message altogether, because there is no
1727       --  obvious node (for now) on which to post it. On the other hand the
1728       --  offending node must be replaced with a constraint_error in any case.
1729
1730       --  No messages are generated if we already posted an error on this node
1731
1732       if not Error_Posted (N) then
1733          if Loc /= No_Location then
1734             Eloc := Loc;
1735          else
1736             Eloc := Sloc (N);
1737          end if;
1738
1739          Msgc (1 .. Msg'Length) := Msg;
1740          Msgl := Msg'Length;
1741
1742          --  Message is a warning, even in Ada 95 case
1743
1744          if Msg (Msg'Last) = '?' then
1745             Wmsg := True;
1746
1747          --  In Ada 83, all messages are warnings. In the private part and
1748          --  the body of an instance, constraint_checks are only warnings.
1749          --  We also make this a warning if the Warn parameter is set.
1750
1751          elsif Warn
1752            or else (Ada_Version = Ada_83 and then Comes_From_Source (N))
1753          then
1754             Msgl := Msgl + 1;
1755             Msgc (Msgl) := '?';
1756             Wmsg := True;
1757
1758          elsif In_Instance_Not_Visible then
1759             Msgl := Msgl + 1;
1760             Msgc (Msgl) := '?';
1761             Wmsg := True;
1762
1763          --  Otherwise we have a real error message (Ada 95 static case)
1764          --  and we make this an unconditional message. Note that in the
1765          --  warning case we do not make the message unconditional, it seems
1766          --  quite reasonable to delete messages like this (about exceptions
1767          --  that will be raised) in dead code.
1768
1769          else
1770             Wmsg := False;
1771             Msgl := Msgl + 1;
1772             Msgc (Msgl) := '!';
1773          end if;
1774
1775          --  Should we generate a warning? The answer is not quite yes. The
1776          --  very annoying exception occurs in the case of a short circuit
1777          --  operator where the left operand is static and decisive. Climb
1778          --  parents to see if that is the case we have here. Conditional
1779          --  expressions with decisive conditions are a similar situation.
1780
1781          Msgs := True;
1782          P := N;
1783          loop
1784             OldP := P;
1785             P := Parent (P);
1786
1787             --  And then with False as left operand
1788
1789             if Nkind (P) = N_And_Then
1790               and then Compile_Time_Known_Value (Left_Opnd (P))
1791               and then Is_False (Expr_Value (Left_Opnd (P)))
1792             then
1793                Msgs := False;
1794                exit;
1795
1796             --  OR ELSE with True as left operand
1797
1798             elsif Nkind (P) = N_Or_Else
1799               and then Compile_Time_Known_Value (Left_Opnd (P))
1800               and then Is_True (Expr_Value (Left_Opnd (P)))
1801             then
1802                Msgs := False;
1803                exit;
1804
1805             --  Conditional expression
1806
1807             elsif Nkind (P) = N_Conditional_Expression then
1808                declare
1809                   Cond : constant Node_Id := First (Expressions (P));
1810                   Texp : constant Node_Id := Next (Cond);
1811                   Fexp : constant Node_Id := Next (Texp);
1812
1813                begin
1814                   if Compile_Time_Known_Value (Cond) then
1815
1816                      --  Condition is True and we are in the right operand
1817
1818                      if Is_True (Expr_Value (Cond))
1819                        and then OldP = Fexp
1820                      then
1821                         Msgs := False;
1822                         exit;
1823
1824                      --  Condition is False and we are in the left operand
1825
1826                      elsif Is_False (Expr_Value (Cond))
1827                        and then OldP = Texp
1828                      then
1829                         Msgs := False;
1830                         exit;
1831                      end if;
1832                   end if;
1833                end;
1834
1835             --  Special case for component association in aggregates, where
1836             --  we want to keep climbing up to the parent aggregate.
1837
1838             elsif Nkind (P) = N_Component_Association
1839               and then Nkind (Parent (P)) = N_Aggregate
1840             then
1841                null;
1842
1843             --  Keep going if within subexpression
1844
1845             else
1846                exit when Nkind (P) not in N_Subexpr;
1847             end if;
1848          end loop;
1849
1850          if Msgs then
1851             if Present (Ent) then
1852                Error_Msg_NEL (Msgc (1 .. Msgl), N, Ent, Eloc);
1853             else
1854                Error_Msg_NEL (Msgc (1 .. Msgl), N, Etype (N), Eloc);
1855             end if;
1856
1857             if Wmsg then
1858                if Inside_Init_Proc then
1859                   Error_Msg_NEL
1860                     ("\?& will be raised for objects of this type",
1861                      N, Standard_Constraint_Error, Eloc);
1862                else
1863                   Error_Msg_NEL
1864                     ("\?& will be raised at run time",
1865                      N, Standard_Constraint_Error, Eloc);
1866                end if;
1867
1868             else
1869                Error_Msg
1870                  ("\static expression fails Constraint_Check", Eloc);
1871                Set_Error_Posted (N);
1872             end if;
1873          end if;
1874       end if;
1875
1876       return N;
1877    end Compile_Time_Constraint_Error;
1878
1879    -----------------------
1880    -- Conditional_Delay --
1881    -----------------------
1882
1883    procedure Conditional_Delay (New_Ent, Old_Ent : Entity_Id) is
1884    begin
1885       if Has_Delayed_Freeze (Old_Ent) and then not Is_Frozen (Old_Ent) then
1886          Set_Has_Delayed_Freeze (New_Ent);
1887       end if;
1888    end Conditional_Delay;
1889
1890    -------------------------
1891    -- Copy_Parameter_List --
1892    -------------------------
1893
1894    function Copy_Parameter_List (Subp_Id : Entity_Id) return List_Id is
1895       Loc    : constant Source_Ptr := Sloc (Subp_Id);
1896       Plist  : List_Id;
1897       Formal : Entity_Id;
1898
1899    begin
1900       if No (First_Formal (Subp_Id)) then
1901          return No_List;
1902       else
1903          Plist := New_List;
1904          Formal := First_Formal (Subp_Id);
1905          while Present (Formal) loop
1906             Append
1907               (Make_Parameter_Specification (Loc,
1908                 Defining_Identifier =>
1909                   Make_Defining_Identifier (Sloc (Formal),
1910                     Chars => Chars (Formal)),
1911                 In_Present  => In_Present (Parent (Formal)),
1912                 Out_Present => Out_Present (Parent (Formal)),
1913              Parameter_Type =>
1914                   New_Reference_To (Etype (Formal), Loc),
1915                 Expression =>
1916                   New_Copy_Tree (Expression (Parent (Formal)))),
1917               Plist);
1918
1919             Next_Formal (Formal);
1920          end loop;
1921       end if;
1922
1923       return Plist;
1924    end Copy_Parameter_List;
1925
1926    --------------------
1927    -- Current_Entity --
1928    --------------------
1929
1930    --  The currently visible definition for a given identifier is the
1931    --  one most chained at the start of the visibility chain, i.e. the
1932    --  one that is referenced by the Node_Id value of the name of the
1933    --  given identifier.
1934
1935    function Current_Entity (N : Node_Id) return Entity_Id is
1936    begin
1937       return Get_Name_Entity_Id (Chars (N));
1938    end Current_Entity;
1939
1940    -----------------------------
1941    -- Current_Entity_In_Scope --
1942    -----------------------------
1943
1944    function Current_Entity_In_Scope (N : Node_Id) return Entity_Id is
1945       E  : Entity_Id;
1946       CS : constant Entity_Id := Current_Scope;
1947
1948       Transient_Case : constant Boolean := Scope_Is_Transient;
1949
1950    begin
1951       E := Get_Name_Entity_Id (Chars (N));
1952       while Present (E)
1953         and then Scope (E) /= CS
1954         and then (not Transient_Case or else Scope (E) /= Scope (CS))
1955       loop
1956          E := Homonym (E);
1957       end loop;
1958
1959       return E;
1960    end Current_Entity_In_Scope;
1961
1962    -------------------
1963    -- Current_Scope --
1964    -------------------
1965
1966    function Current_Scope return Entity_Id is
1967    begin
1968       if Scope_Stack.Last = -1 then
1969          return Standard_Standard;
1970       else
1971          declare
1972             C : constant Entity_Id :=
1973                   Scope_Stack.Table (Scope_Stack.Last).Entity;
1974          begin
1975             if Present (C) then
1976                return C;
1977             else
1978                return Standard_Standard;
1979             end if;
1980          end;
1981       end if;
1982    end Current_Scope;
1983
1984    ------------------------
1985    -- Current_Subprogram --
1986    ------------------------
1987
1988    function Current_Subprogram return Entity_Id is
1989       Scop : constant Entity_Id := Current_Scope;
1990    begin
1991       if Is_Subprogram (Scop) or else Is_Generic_Subprogram (Scop) then
1992          return Scop;
1993       else
1994          return Enclosing_Subprogram (Scop);
1995       end if;
1996    end Current_Subprogram;
1997
1998    ---------------------
1999    -- Defining_Entity --
2000    ---------------------
2001
2002    function Defining_Entity (N : Node_Id) return Entity_Id is
2003       K   : constant Node_Kind := Nkind (N);
2004       Err : Entity_Id := Empty;
2005
2006    begin
2007       case K is
2008          when
2009            N_Subprogram_Declaration                 |
2010            N_Abstract_Subprogram_Declaration        |
2011            N_Subprogram_Body                        |
2012            N_Package_Declaration                    |
2013            N_Subprogram_Renaming_Declaration        |
2014            N_Subprogram_Body_Stub                   |
2015            N_Generic_Subprogram_Declaration         |
2016            N_Generic_Package_Declaration            |
2017            N_Formal_Subprogram_Declaration
2018          =>
2019             return Defining_Entity (Specification (N));
2020
2021          when
2022            N_Component_Declaration                  |
2023            N_Defining_Program_Unit_Name             |
2024            N_Discriminant_Specification             |
2025            N_Entry_Body                             |
2026            N_Entry_Declaration                      |
2027            N_Entry_Index_Specification              |
2028            N_Exception_Declaration                  |
2029            N_Exception_Renaming_Declaration         |
2030            N_Formal_Object_Declaration              |
2031            N_Formal_Package_Declaration             |
2032            N_Formal_Type_Declaration                |
2033            N_Full_Type_Declaration                  |
2034            N_Implicit_Label_Declaration             |
2035            N_Incomplete_Type_Declaration            |
2036            N_Loop_Parameter_Specification           |
2037            N_Number_Declaration                     |
2038            N_Object_Declaration                     |
2039            N_Object_Renaming_Declaration            |
2040            N_Package_Body_Stub                      |
2041            N_Parameter_Specification                |
2042            N_Private_Extension_Declaration          |
2043            N_Private_Type_Declaration               |
2044            N_Protected_Body                         |
2045            N_Protected_Body_Stub                    |
2046            N_Protected_Type_Declaration             |
2047            N_Single_Protected_Declaration           |
2048            N_Single_Task_Declaration                |
2049            N_Subtype_Declaration                    |
2050            N_Task_Body                              |
2051            N_Task_Body_Stub                         |
2052            N_Task_Type_Declaration
2053          =>
2054             return Defining_Identifier (N);
2055
2056          when N_Subunit =>
2057             return Defining_Entity (Proper_Body (N));
2058
2059          when
2060            N_Function_Instantiation                 |
2061            N_Function_Specification                 |
2062            N_Generic_Function_Renaming_Declaration  |
2063            N_Generic_Package_Renaming_Declaration   |
2064            N_Generic_Procedure_Renaming_Declaration |
2065            N_Package_Body                           |
2066            N_Package_Instantiation                  |
2067            N_Package_Renaming_Declaration           |
2068            N_Package_Specification                  |
2069            N_Procedure_Instantiation                |
2070            N_Procedure_Specification
2071          =>
2072             declare
2073                Nam : constant Node_Id := Defining_Unit_Name (N);
2074
2075             begin
2076                if Nkind (Nam) in N_Entity then
2077                   return Nam;
2078
2079                --  For Error, make up a name and attach to declaration
2080                --  so we can continue semantic analysis
2081
2082                elsif Nam = Error then
2083                   Err :=
2084                     Make_Defining_Identifier (Sloc (N),
2085                       Chars => New_Internal_Name ('T'));
2086                   Set_Defining_Unit_Name (N, Err);
2087
2088                   return Err;
2089                --  If not an entity, get defining identifier
2090
2091                else
2092                   return Defining_Identifier (Nam);
2093                end if;
2094             end;
2095
2096          when N_Block_Statement =>
2097             return Entity (Identifier (N));
2098
2099          when others =>
2100             raise Program_Error;
2101
2102       end case;
2103    end Defining_Entity;
2104
2105    --------------------------
2106    -- Denotes_Discriminant --
2107    --------------------------
2108
2109    function Denotes_Discriminant
2110      (N                : Node_Id;
2111       Check_Concurrent : Boolean := False) return Boolean
2112    is
2113       E : Entity_Id;
2114    begin
2115       if not Is_Entity_Name (N)
2116         or else No (Entity (N))
2117       then
2118          return False;
2119       else
2120          E := Entity (N);
2121       end if;
2122
2123       --  If we are checking for a protected type, the discriminant may have
2124       --  been rewritten as the corresponding discriminal of the original type
2125       --  or of the corresponding concurrent record, depending on whether we
2126       --  are in the spec or body of the protected type.
2127
2128       return Ekind (E) = E_Discriminant
2129         or else
2130           (Check_Concurrent
2131             and then Ekind (E) = E_In_Parameter
2132             and then Present (Discriminal_Link (E))
2133             and then
2134               (Is_Concurrent_Type (Scope (Discriminal_Link (E)))
2135                 or else
2136                   Is_Concurrent_Record_Type (Scope (Discriminal_Link (E)))));
2137
2138    end Denotes_Discriminant;
2139
2140    -------------------------
2141    -- Denotes_Same_Object --
2142    -------------------------
2143
2144    function Denotes_Same_Object (A1, A2 : Node_Id) return Boolean is
2145    begin
2146       --  If we have entity names, then must be same entity
2147
2148       if Is_Entity_Name (A1) then
2149          if Is_Entity_Name (A2) then
2150             return Entity (A1) = Entity (A2);
2151          else
2152             return False;
2153          end if;
2154
2155       --  No match if not same node kind
2156
2157       elsif Nkind (A1) /= Nkind (A2) then
2158          return False;
2159
2160       --  For selected components, must have same prefix and selector
2161
2162       elsif Nkind (A1) = N_Selected_Component then
2163          return Denotes_Same_Object (Prefix (A1), Prefix (A2))
2164            and then
2165          Entity (Selector_Name (A1)) = Entity (Selector_Name (A2));
2166
2167       --  For explicit dereferences, prefixes must be same
2168
2169       elsif Nkind (A1) = N_Explicit_Dereference then
2170          return Denotes_Same_Object (Prefix (A1), Prefix (A2));
2171
2172       --  For indexed components, prefixes and all subscripts must be the same
2173
2174       elsif Nkind (A1) = N_Indexed_Component then
2175          if Denotes_Same_Object (Prefix (A1), Prefix (A2)) then
2176             declare
2177                Indx1 : Node_Id;
2178                Indx2 : Node_Id;
2179
2180             begin
2181                Indx1 := First (Expressions (A1));
2182                Indx2 := First (Expressions (A2));
2183                while Present (Indx1) loop
2184
2185                   --  Shouldn't we be checking that values are the same???
2186
2187                   if not Denotes_Same_Object (Indx1, Indx2) then
2188                      return False;
2189                   end if;
2190
2191                   Next (Indx1);
2192                   Next (Indx2);
2193                end loop;
2194
2195                return True;
2196             end;
2197          else
2198             return False;
2199          end if;
2200
2201       --  For slices, prefixes must match and bounds must match
2202
2203       elsif Nkind (A1) = N_Slice
2204         and then Denotes_Same_Object (Prefix (A1), Prefix (A2))
2205       then
2206          declare
2207             Lo1, Lo2, Hi1, Hi2 : Node_Id;
2208
2209          begin
2210             Get_Index_Bounds (Etype (A1), Lo1, Hi1);
2211             Get_Index_Bounds (Etype (A2), Lo2, Hi2);
2212
2213             --  Check whether bounds are statically identical. There is no
2214             --  attempt to detect partial overlap of slices.
2215
2216             --  What about an array and a slice of an array???
2217
2218             return Denotes_Same_Object (Lo1, Lo2)
2219               and then Denotes_Same_Object (Hi1, Hi2);
2220          end;
2221
2222          --  Literals will appear as indices. Isn't this where we should check
2223          --  Known_At_Compile_Time at least if we are generating warnings ???
2224
2225       elsif Nkind (A1) = N_Integer_Literal then
2226          return Intval (A1) = Intval (A2);
2227
2228       else
2229          return False;
2230       end if;
2231    end Denotes_Same_Object;
2232
2233    -------------------------
2234    -- Denotes_Same_Prefix --
2235    -------------------------
2236
2237    function Denotes_Same_Prefix (A1, A2 : Node_Id) return Boolean is
2238
2239    begin
2240       if Is_Entity_Name (A1) then
2241          if Nkind_In (A2, N_Selected_Component, N_Indexed_Component) then
2242             return Denotes_Same_Object (A1, Prefix (A2))
2243               or else Denotes_Same_Prefix (A1, Prefix (A2));
2244          else
2245             return False;
2246          end if;
2247
2248       elsif Is_Entity_Name (A2) then
2249          return Denotes_Same_Prefix (A2, A1);
2250
2251       elsif Nkind_In (A1, N_Selected_Component, N_Indexed_Component, N_Slice)
2252               and then
2253             Nkind_In (A2, N_Selected_Component, N_Indexed_Component, N_Slice)
2254       then
2255          declare
2256             Root1, Root2 : Node_Id;
2257             Depth1, Depth2 : Int := 0;
2258
2259          begin
2260             Root1 := Prefix (A1);
2261             while not Is_Entity_Name (Root1) loop
2262                if not Nkind_In
2263                  (Root1, N_Selected_Component, N_Indexed_Component)
2264                then
2265                   return False;
2266                else
2267                   Root1 := Prefix (Root1);
2268                end if;
2269
2270                Depth1 := Depth1 + 1;
2271             end loop;
2272
2273             Root2 := Prefix (A2);
2274             while not Is_Entity_Name (Root2) loop
2275                if not Nkind_In
2276                  (Root2, N_Selected_Component, N_Indexed_Component)
2277                then
2278                   return False;
2279                else
2280                   Root2 := Prefix (Root2);
2281                end if;
2282
2283                Depth2 := Depth2 + 1;
2284             end loop;
2285
2286             --  If both have the same depth and they do not denote the same
2287             --  object, they are disjoint and not warning is needed.
2288
2289             if Depth1 = Depth2 then
2290                return False;
2291
2292             elsif Depth1 > Depth2 then
2293                Root1 := Prefix (A1);
2294                for I in 1 .. Depth1 - Depth2 - 1 loop
2295                   Root1 := Prefix (Root1);
2296                end loop;
2297
2298                return Denotes_Same_Object (Root1, A2);
2299
2300             else
2301                Root2 := Prefix (A2);
2302                for I in 1 .. Depth2 - Depth1 - 1 loop
2303                   Root2 := Prefix (Root2);
2304                end loop;
2305
2306                return Denotes_Same_Object (A1, Root2);
2307             end if;
2308          end;
2309
2310       else
2311          return False;
2312       end if;
2313    end Denotes_Same_Prefix;
2314
2315    ----------------------
2316    -- Denotes_Variable --
2317    ----------------------
2318
2319    function Denotes_Variable (N : Node_Id) return Boolean is
2320    begin
2321       return Is_Variable (N) and then Paren_Count (N) = 0;
2322    end Denotes_Variable;
2323
2324    -----------------------------
2325    -- Depends_On_Discriminant --
2326    -----------------------------
2327
2328    function Depends_On_Discriminant (N : Node_Id) return Boolean is
2329       L : Node_Id;
2330       H : Node_Id;
2331
2332    begin
2333       Get_Index_Bounds (N, L, H);
2334       return Denotes_Discriminant (L) or else Denotes_Discriminant (H);
2335    end Depends_On_Discriminant;
2336
2337    -------------------------
2338    -- Designate_Same_Unit --
2339    -------------------------
2340
2341    function Designate_Same_Unit
2342      (Name1 : Node_Id;
2343       Name2 : Node_Id) return Boolean
2344    is
2345       K1 : constant Node_Kind := Nkind (Name1);
2346       K2 : constant Node_Kind := Nkind (Name2);
2347
2348       function Prefix_Node (N : Node_Id) return Node_Id;
2349       --  Returns the parent unit name node of a defining program unit name
2350       --  or the prefix if N is a selected component or an expanded name.
2351
2352       function Select_Node (N : Node_Id) return Node_Id;
2353       --  Returns the defining identifier node of a defining program unit
2354       --  name or  the selector node if N is a selected component or an
2355       --  expanded name.
2356
2357       -----------------
2358       -- Prefix_Node --
2359       -----------------
2360
2361       function Prefix_Node (N : Node_Id) return Node_Id is
2362       begin
2363          if Nkind (N) = N_Defining_Program_Unit_Name then
2364             return Name (N);
2365
2366          else
2367             return Prefix (N);
2368          end if;
2369       end Prefix_Node;
2370
2371       -----------------
2372       -- Select_Node --
2373       -----------------
2374
2375       function Select_Node (N : Node_Id) return Node_Id is
2376       begin
2377          if Nkind (N) = N_Defining_Program_Unit_Name then
2378             return Defining_Identifier (N);
2379
2380          else
2381             return Selector_Name (N);
2382          end if;
2383       end Select_Node;
2384
2385    --  Start of processing for Designate_Next_Unit
2386
2387    begin
2388       if (K1 = N_Identifier or else
2389           K1 = N_Defining_Identifier)
2390         and then
2391          (K2 = N_Identifier or else
2392           K2 = N_Defining_Identifier)
2393       then
2394          return Chars (Name1) = Chars (Name2);
2395
2396       elsif
2397          (K1 = N_Expanded_Name      or else
2398           K1 = N_Selected_Component or else
2399           K1 = N_Defining_Program_Unit_Name)
2400         and then
2401          (K2 = N_Expanded_Name      or else
2402           K2 = N_Selected_Component or else
2403           K2 = N_Defining_Program_Unit_Name)
2404       then
2405          return
2406            (Chars (Select_Node (Name1)) = Chars (Select_Node (Name2)))
2407              and then
2408                Designate_Same_Unit (Prefix_Node (Name1), Prefix_Node (Name2));
2409
2410       else
2411          return False;
2412       end if;
2413    end Designate_Same_Unit;
2414
2415    ----------------------------
2416    -- Enclosing_Generic_Body --
2417    ----------------------------
2418
2419    function Enclosing_Generic_Body
2420      (N : Node_Id) return Node_Id
2421    is
2422       P    : Node_Id;
2423       Decl : Node_Id;
2424       Spec : Node_Id;
2425
2426    begin
2427       P := Parent (N);
2428       while Present (P) loop
2429          if Nkind (P) = N_Package_Body
2430            or else Nkind (P) = N_Subprogram_Body
2431          then
2432             Spec := Corresponding_Spec (P);
2433
2434             if Present (Spec) then
2435                Decl := Unit_Declaration_Node (Spec);
2436
2437                if Nkind (Decl) = N_Generic_Package_Declaration
2438                  or else Nkind (Decl) = N_Generic_Subprogram_Declaration
2439                then
2440                   return P;
2441                end if;
2442             end if;
2443          end if;
2444
2445          P := Parent (P);
2446       end loop;
2447
2448       return Empty;
2449    end Enclosing_Generic_Body;
2450
2451    ----------------------------
2452    -- Enclosing_Generic_Unit --
2453    ----------------------------
2454
2455    function Enclosing_Generic_Unit
2456      (N : Node_Id) return Node_Id
2457    is
2458       P    : Node_Id;
2459       Decl : Node_Id;
2460       Spec : Node_Id;
2461
2462    begin
2463       P := Parent (N);
2464       while Present (P) loop
2465          if Nkind (P) = N_Generic_Package_Declaration
2466            or else Nkind (P) = N_Generic_Subprogram_Declaration
2467          then
2468             return P;
2469
2470          elsif Nkind (P) = N_Package_Body
2471            or else Nkind (P) = N_Subprogram_Body
2472          then
2473             Spec := Corresponding_Spec (P);
2474
2475             if Present (Spec) then
2476                Decl := Unit_Declaration_Node (Spec);
2477
2478                if Nkind (Decl) = N_Generic_Package_Declaration
2479                  or else Nkind (Decl) = N_Generic_Subprogram_Declaration
2480                then
2481                   return Decl;
2482                end if;
2483             end if;
2484          end if;
2485
2486          P := Parent (P);
2487       end loop;
2488
2489       return Empty;
2490    end Enclosing_Generic_Unit;
2491
2492    -------------------------------
2493    -- Enclosing_Lib_Unit_Entity --
2494    -------------------------------
2495
2496    function Enclosing_Lib_Unit_Entity return Entity_Id is
2497       Unit_Entity : Entity_Id;
2498
2499    begin
2500       --  Look for enclosing library unit entity by following scope links.
2501       --  Equivalent to, but faster than indexing through the scope stack.
2502
2503       Unit_Entity := Current_Scope;
2504       while (Present (Scope (Unit_Entity))
2505         and then Scope (Unit_Entity) /= Standard_Standard)
2506         and not Is_Child_Unit (Unit_Entity)
2507       loop
2508          Unit_Entity := Scope (Unit_Entity);
2509       end loop;
2510
2511       return Unit_Entity;
2512    end Enclosing_Lib_Unit_Entity;
2513
2514    -----------------------------
2515    -- Enclosing_Lib_Unit_Node --
2516    -----------------------------
2517
2518    function Enclosing_Lib_Unit_Node (N : Node_Id) return Node_Id is
2519       Current_Node : Node_Id;
2520
2521    begin
2522       Current_Node := N;
2523       while Present (Current_Node)
2524         and then Nkind (Current_Node) /= N_Compilation_Unit
2525       loop
2526          Current_Node := Parent (Current_Node);
2527       end loop;
2528
2529       if Nkind (Current_Node) /= N_Compilation_Unit then
2530          return Empty;
2531       end if;
2532
2533       return Current_Node;
2534    end Enclosing_Lib_Unit_Node;
2535
2536    --------------------------
2537    -- Enclosing_Subprogram --
2538    --------------------------
2539
2540    function Enclosing_Subprogram (E : Entity_Id) return Entity_Id is
2541       Dynamic_Scope : constant Entity_Id := Enclosing_Dynamic_Scope (E);
2542
2543    begin
2544       if Dynamic_Scope = Standard_Standard then
2545          return Empty;
2546
2547       elsif Dynamic_Scope = Empty then
2548          return Empty;
2549
2550       elsif Ekind (Dynamic_Scope) = E_Subprogram_Body then
2551          return Corresponding_Spec (Parent (Parent (Dynamic_Scope)));
2552
2553       elsif Ekind (Dynamic_Scope) = E_Block
2554         or else Ekind (Dynamic_Scope) = E_Return_Statement
2555       then
2556          return Enclosing_Subprogram (Dynamic_Scope);
2557
2558       elsif Ekind (Dynamic_Scope) = E_Task_Type then
2559          return Get_Task_Body_Procedure (Dynamic_Scope);
2560
2561       elsif Convention (Dynamic_Scope) = Convention_Protected then
2562          return Protected_Body_Subprogram (Dynamic_Scope);
2563
2564       else
2565          return Dynamic_Scope;
2566       end if;
2567    end Enclosing_Subprogram;
2568
2569    ------------------------
2570    -- Ensure_Freeze_Node --
2571    ------------------------
2572
2573    procedure Ensure_Freeze_Node (E : Entity_Id) is
2574       FN : Node_Id;
2575
2576    begin
2577       if No (Freeze_Node (E)) then
2578          FN := Make_Freeze_Entity (Sloc (E));
2579          Set_Has_Delayed_Freeze (E);
2580          Set_Freeze_Node (E, FN);
2581          Set_Access_Types_To_Process (FN, No_Elist);
2582          Set_TSS_Elist (FN, No_Elist);
2583          Set_Entity (FN, E);
2584       end if;
2585    end Ensure_Freeze_Node;
2586
2587    ----------------
2588    -- Enter_Name --
2589    ----------------
2590
2591    procedure Enter_Name (Def_Id : Entity_Id) is
2592       C : constant Entity_Id := Current_Entity (Def_Id);
2593       E : constant Entity_Id := Current_Entity_In_Scope (Def_Id);
2594       S : constant Entity_Id := Current_Scope;
2595
2596    begin
2597       Generate_Definition (Def_Id);
2598
2599       --  Add new name to current scope declarations. Check for duplicate
2600       --  declaration, which may or may not be a genuine error.
2601
2602       if Present (E) then
2603
2604          --  Case of previous entity entered because of a missing declaration
2605          --  or else a bad subtype indication. Best is to use the new entity,
2606          --  and make the previous one invisible.
2607
2608          if Etype (E) = Any_Type then
2609             Set_Is_Immediately_Visible (E, False);
2610
2611          --  Case of renaming declaration constructed for package instances.
2612          --  if there is an explicit declaration with the same identifier,
2613          --  the renaming is not immediately visible any longer, but remains
2614          --  visible through selected component notation.
2615
2616          elsif Nkind (Parent (E)) = N_Package_Renaming_Declaration
2617            and then not Comes_From_Source (E)
2618          then
2619             Set_Is_Immediately_Visible (E, False);
2620
2621          --  The new entity may be the package renaming, which has the same
2622          --  same name as a generic formal which has been seen already.
2623
2624          elsif Nkind (Parent (Def_Id)) = N_Package_Renaming_Declaration
2625             and then not Comes_From_Source (Def_Id)
2626          then
2627             Set_Is_Immediately_Visible (E, False);
2628
2629          --  For a fat pointer corresponding to a remote access to subprogram,
2630          --  we use the same identifier as the RAS type, so that the proper
2631          --  name appears in the stub. This type is only retrieved through
2632          --  the RAS type and never by visibility, and is not added to the
2633          --  visibility list (see below).
2634
2635          elsif Nkind (Parent (Def_Id)) = N_Full_Type_Declaration
2636            and then Present (Corresponding_Remote_Type (Def_Id))
2637          then
2638             null;
2639
2640          --  A controller component for a type extension overrides the
2641          --  inherited component.
2642
2643          elsif Chars (E) = Name_uController then
2644             null;
2645
2646          --  Case of an implicit operation or derived literal. The new entity
2647          --  hides the implicit one,  which is removed from all visibility,
2648          --  i.e. the entity list of its scope, and homonym chain of its name.
2649
2650          elsif (Is_Overloadable (E) and then Is_Inherited_Operation (E))
2651            or else Is_Internal (E)
2652          then
2653             declare
2654                Prev     : Entity_Id;
2655                Prev_Vis : Entity_Id;
2656                Decl     : constant Node_Id := Parent (E);
2657
2658             begin
2659                --  If E is an implicit declaration, it cannot be the first
2660                --  entity in the scope.
2661
2662                Prev := First_Entity (Current_Scope);
2663                while Present (Prev)
2664                  and then Next_Entity (Prev) /= E
2665                loop
2666                   Next_Entity (Prev);
2667                end loop;
2668
2669                if No (Prev) then
2670
2671                   --  If E is not on the entity chain of the current scope,
2672                   --  it is an implicit declaration in the generic formal
2673                   --  part of a generic subprogram. When analyzing the body,
2674                   --  the generic formals are visible but not on the entity
2675                   --  chain of the subprogram. The new entity will become
2676                   --  the visible one in the body.
2677
2678                   pragma Assert
2679                     (Nkind (Parent (Decl)) = N_Generic_Subprogram_Declaration);
2680                   null;
2681
2682                else
2683                   Set_Next_Entity (Prev, Next_Entity (E));
2684
2685                   if No (Next_Entity (Prev)) then
2686                      Set_Last_Entity (Current_Scope, Prev);
2687                   end if;
2688
2689                   if E = Current_Entity (E) then
2690                      Prev_Vis := Empty;
2691
2692                   else
2693                      Prev_Vis := Current_Entity (E);
2694                      while Homonym (Prev_Vis) /= E loop
2695                         Prev_Vis := Homonym (Prev_Vis);
2696                      end loop;
2697                   end if;
2698
2699                   if Present (Prev_Vis)  then
2700
2701                      --  Skip E in the visibility chain
2702
2703                      Set_Homonym (Prev_Vis, Homonym (E));
2704
2705                   else
2706                      Set_Name_Entity_Id (Chars (E), Homonym (E));
2707                   end if;
2708                end if;
2709             end;
2710
2711          --  This section of code could use a comment ???
2712
2713          elsif Present (Etype (E))
2714            and then Is_Concurrent_Type (Etype (E))
2715            and then E = Def_Id
2716          then
2717             return;
2718
2719          --  If the homograph is a protected component renaming, it should not
2720          --  be hiding the current entity. Such renamings are treated as weak
2721          --  declarations.
2722
2723          elsif Is_Prival (E) then
2724             Set_Is_Immediately_Visible (E, False);
2725
2726          --  In this case the current entity is a protected component renaming.
2727          --  Perform minimal decoration by setting the scope and return since
2728          --  the prival should not be hiding other visible entities.
2729
2730          elsif Is_Prival (Def_Id) then
2731             Set_Scope (Def_Id, Current_Scope);
2732             return;
2733
2734          --  Analogous to privals, the discriminal generated for an entry
2735          --  index parameter acts as a weak declaration. Perform minimal
2736          --  decoration to avoid bogus errors.
2737
2738          elsif Is_Discriminal (Def_Id)
2739            and then Ekind (Discriminal_Link (Def_Id)) = E_Entry_Index_Parameter
2740          then
2741             Set_Scope (Def_Id, Current_Scope);
2742             return;
2743
2744          --  In the body or private part of an instance, a type extension
2745          --  may introduce a component with the same name as that of an
2746          --  actual. The legality rule is not enforced, but the semantics
2747          --  of the full type with two components of the same name are not
2748          --  clear at this point ???
2749
2750          elsif In_Instance_Not_Visible then
2751             null;
2752
2753          --  When compiling a package body, some child units may have become
2754          --  visible. They cannot conflict with local entities that hide them.
2755
2756          elsif Is_Child_Unit (E)
2757            and then In_Open_Scopes (Scope (E))
2758            and then not Is_Immediately_Visible (E)
2759          then
2760             null;
2761
2762          --  Conversely, with front-end inlining we may compile the parent
2763          --  body first, and a child unit subsequently. The context is now
2764          --  the parent spec, and body entities are not visible.
2765
2766          elsif Is_Child_Unit (Def_Id)
2767            and then Is_Package_Body_Entity (E)
2768            and then not In_Package_Body (Current_Scope)
2769          then
2770             null;
2771
2772          --  Case of genuine duplicate declaration
2773
2774          else
2775             Error_Msg_Sloc := Sloc (E);
2776
2777             --  If the previous declaration is an incomplete type declaration
2778             --  this may be an attempt to complete it with a private type.
2779             --  The following avoids confusing cascaded errors.
2780
2781             if Nkind (Parent (E)) = N_Incomplete_Type_Declaration
2782               and then Nkind (Parent (Def_Id)) = N_Private_Type_Declaration
2783             then
2784                Error_Msg_N
2785                  ("incomplete type cannot be completed with a private " &
2786                   "declaration", Parent (Def_Id));
2787                Set_Is_Immediately_Visible (E, False);
2788                Set_Full_View (E, Def_Id);
2789
2790             --  An inherited component of a record conflicts with a new
2791             --  discriminant. The discriminant is inserted first in the scope,
2792             --  but the error should be posted on it, not on the component.
2793
2794             elsif Ekind (E) = E_Discriminant
2795               and then Present (Scope (Def_Id))
2796               and then Scope (Def_Id) /= Current_Scope
2797             then
2798                Error_Msg_Sloc := Sloc (Def_Id);
2799                Error_Msg_N ("& conflicts with declaration#", E);
2800                return;
2801
2802             --  If the name of the unit appears in its own context clause,
2803             --  a dummy package with the name has already been created, and
2804             --  the error emitted. Try to continue quietly.
2805
2806             elsif Error_Posted (E)
2807               and then Sloc (E) = No_Location
2808               and then Nkind (Parent (E)) = N_Package_Specification
2809               and then Current_Scope = Standard_Standard
2810             then
2811                Set_Scope (Def_Id, Current_Scope);
2812                return;
2813
2814             else
2815                Error_Msg_N ("& conflicts with declaration#", Def_Id);
2816
2817                --  Avoid cascaded messages with duplicate components in
2818                --  derived types.
2819
2820                if Ekind (E) = E_Component
2821                  or else Ekind (E) = E_Discriminant
2822                then
2823                   return;
2824                end if;
2825             end if;
2826
2827             if Nkind (Parent (Parent (Def_Id))) =
2828                 N_Generic_Subprogram_Declaration
2829               and then Def_Id =
2830                 Defining_Entity (Specification (Parent (Parent (Def_Id))))
2831             then
2832                Error_Msg_N ("\generic units cannot be overloaded", Def_Id);
2833             end if;
2834
2835             --  If entity is in standard, then we are in trouble, because
2836             --  it means that we have a library package with a duplicated
2837             --  name. That's hard to recover from, so abort!
2838
2839             if S = Standard_Standard then
2840                raise Unrecoverable_Error;
2841
2842             --  Otherwise we continue with the declaration. Having two
2843             --  identical declarations should not cause us too much trouble!
2844
2845             else
2846                null;
2847             end if;
2848          end if;
2849       end if;
2850
2851       --  If we fall through, declaration is OK , or OK enough to continue
2852
2853       --  If Def_Id is a discriminant or a record component we are in the
2854       --  midst of inheriting components in a derived record definition.
2855       --  Preserve their Ekind and Etype.
2856
2857       if Ekind (Def_Id) = E_Discriminant
2858         or else Ekind (Def_Id) = E_Component
2859       then
2860          null;
2861
2862       --  If a type is already set, leave it alone (happens whey a type
2863       --  declaration is reanalyzed following a call to the optimizer)
2864
2865       elsif Present (Etype (Def_Id)) then
2866          null;
2867
2868       --  Otherwise, the kind E_Void insures that premature uses of the entity
2869       --  will be detected. Any_Type insures that no cascaded errors will occur
2870
2871       else
2872          Set_Ekind (Def_Id, E_Void);
2873          Set_Etype (Def_Id, Any_Type);
2874       end if;
2875
2876       --  Inherited discriminants and components in derived record types are
2877       --  immediately visible. Itypes are not.
2878
2879       if Ekind (Def_Id) = E_Discriminant
2880         or else Ekind (Def_Id) = E_Component
2881         or else (No (Corresponding_Remote_Type (Def_Id))
2882                  and then not Is_Itype (Def_Id))
2883       then
2884          Set_Is_Immediately_Visible (Def_Id);
2885          Set_Current_Entity         (Def_Id);
2886       end if;
2887
2888       Set_Homonym       (Def_Id, C);
2889       Append_Entity     (Def_Id, S);
2890       Set_Public_Status (Def_Id);
2891
2892       --  Warn if new entity hides an old one
2893
2894       if Warn_On_Hiding and then Present (C)
2895
2896          --  Don't warn for record components since they always have a well
2897          --  defined scope which does not confuse other uses. Note that in
2898          --  some cases, Ekind has not been set yet.
2899
2900          and then Ekind (C) /= E_Component
2901          and then Ekind (C) /= E_Discriminant
2902          and then Nkind (Parent (C)) /= N_Component_Declaration
2903          and then Ekind (Def_Id) /= E_Component
2904          and then Ekind (Def_Id) /= E_Discriminant
2905          and then Nkind (Parent (Def_Id)) /= N_Component_Declaration
2906
2907          --  Don't warn for one character variables. It is too common to use
2908          --  such variables as locals and will just cause too many false hits.
2909
2910          and then Length_Of_Name (Chars (C)) /= 1
2911
2912          --  Don't warn for non-source entities
2913
2914          and then Comes_From_Source (C)
2915          and then Comes_From_Source (Def_Id)
2916
2917          --  Don't warn unless entity in question is in extended main source
2918
2919          and then In_Extended_Main_Source_Unit (Def_Id)
2920
2921          --  Finally, the hidden entity must be either immediately visible
2922          --  or use visible (from a used package)
2923
2924          and then
2925            (Is_Immediately_Visible (C)
2926               or else
2927             Is_Potentially_Use_Visible (C))
2928       then
2929          Error_Msg_Sloc := Sloc (C);
2930          Error_Msg_N ("declaration hides &#?", Def_Id);
2931       end if;
2932    end Enter_Name;
2933
2934    --------------------------
2935    -- Explain_Limited_Type --
2936    --------------------------
2937
2938    procedure Explain_Limited_Type (T : Entity_Id; N : Node_Id) is
2939       C : Entity_Id;
2940
2941    begin
2942       --  For array, component type must be limited
2943
2944       if Is_Array_Type (T) then
2945          Error_Msg_Node_2 := T;
2946          Error_Msg_NE
2947            ("\component type& of type& is limited", N, Component_Type (T));
2948          Explain_Limited_Type (Component_Type (T), N);
2949
2950       elsif Is_Record_Type (T) then
2951
2952          --  No need for extra messages if explicit limited record
2953
2954          if Is_Limited_Record (Base_Type (T)) then
2955             return;
2956          end if;
2957
2958          --  Otherwise find a limited component. Check only components that
2959          --  come from source, or inherited components that appear in the
2960          --  source of the ancestor.
2961
2962          C := First_Component (T);
2963          while Present (C) loop
2964             if Is_Limited_Type (Etype (C))
2965               and then
2966                 (Comes_From_Source (C)
2967                    or else
2968                      (Present (Original_Record_Component (C))
2969                        and then
2970                          Comes_From_Source (Original_Record_Component (C))))
2971             then
2972                Error_Msg_Node_2 := T;
2973                Error_Msg_NE ("\component& of type& has limited type", N, C);
2974                Explain_Limited_Type (Etype (C), N);
2975                return;
2976             end if;
2977
2978             Next_Component (C);
2979          end loop;
2980
2981          --  The type may be declared explicitly limited, even if no component
2982          --  of it is limited, in which case we fall out of the loop.
2983          return;
2984       end if;
2985    end Explain_Limited_Type;
2986
2987    -----------------
2988    -- Find_Actual --
2989    -----------------
2990
2991    procedure Find_Actual
2992      (N        : Node_Id;
2993       Formal   : out Entity_Id;
2994       Call     : out Node_Id)
2995    is
2996       Parnt  : constant Node_Id := Parent (N);
2997       Actual : Node_Id;
2998
2999    begin
3000       if (Nkind (Parnt) = N_Indexed_Component
3001             or else
3002           Nkind (Parnt) = N_Selected_Component)
3003         and then N = Prefix (Parnt)
3004       then
3005          Find_Actual (Parnt, Formal, Call);
3006          return;
3007
3008       elsif Nkind (Parnt) = N_Parameter_Association
3009         and then N = Explicit_Actual_Parameter (Parnt)
3010       then
3011          Call := Parent (Parnt);
3012
3013       elsif Nkind (Parnt) = N_Procedure_Call_Statement then
3014          Call := Parnt;
3015
3016       else
3017          Formal := Empty;
3018          Call   := Empty;
3019          return;
3020       end if;
3021
3022       --  If we have a call to a subprogram look for the parameter. Note that
3023       --  we exclude overloaded calls, since we don't know enough to be sure
3024       --  of giving the right answer in this case.
3025
3026       if Is_Entity_Name (Name (Call))
3027         and then Present (Entity (Name (Call)))
3028         and then Is_Overloadable (Entity (Name (Call)))
3029         and then not Is_Overloaded (Name (Call))
3030       then
3031          --  Fall here if we are definitely a parameter
3032
3033          Actual := First_Actual (Call);
3034          Formal := First_Formal (Entity (Name (Call)));
3035          while Present (Formal) and then Present (Actual) loop
3036             if Actual = N then
3037                return;
3038             else
3039                Actual := Next_Actual (Actual);
3040                Formal := Next_Formal (Formal);
3041             end if;
3042          end loop;
3043       end if;
3044
3045       --  Fall through here if we did not find matching actual
3046
3047       Formal := Empty;
3048       Call   := Empty;
3049    end Find_Actual;
3050
3051    -------------------------------------
3052    -- Find_Corresponding_Discriminant --
3053    -------------------------------------
3054
3055    function Find_Corresponding_Discriminant
3056      (Id  : Node_Id;
3057       Typ : Entity_Id) return Entity_Id
3058    is
3059       Par_Disc : Entity_Id;
3060       Old_Disc : Entity_Id;
3061       New_Disc : Entity_Id;
3062
3063    begin
3064       Par_Disc := Original_Record_Component (Original_Discriminant (Id));
3065
3066       --  The original type may currently be private, and the discriminant
3067       --  only appear on its full view.
3068
3069       if Is_Private_Type (Scope (Par_Disc))
3070         and then not Has_Discriminants (Scope (Par_Disc))
3071         and then Present (Full_View (Scope (Par_Disc)))
3072       then
3073          Old_Disc := First_Discriminant (Full_View (Scope (Par_Disc)));
3074       else
3075          Old_Disc := First_Discriminant (Scope (Par_Disc));
3076       end if;
3077
3078       if Is_Class_Wide_Type (Typ) then
3079          New_Disc := First_Discriminant (Root_Type (Typ));
3080       else
3081          New_Disc := First_Discriminant (Typ);
3082       end if;
3083
3084       while Present (Old_Disc) and then Present (New_Disc) loop
3085          if Old_Disc = Par_Disc  then
3086             return New_Disc;
3087          else
3088             Next_Discriminant (Old_Disc);
3089             Next_Discriminant (New_Disc);
3090          end if;
3091       end loop;
3092
3093       --  Should always find it
3094
3095       raise Program_Error;
3096    end Find_Corresponding_Discriminant;
3097
3098    --------------------------
3099    -- Find_Overlaid_Entity --
3100    --------------------------
3101
3102    procedure Find_Overlaid_Entity
3103      (N   : Node_Id;
3104       Ent : out Entity_Id;
3105       Off : out Boolean)
3106    is
3107       Expr : Node_Id;
3108
3109    begin
3110       --  We are looking for one of the two following forms:
3111
3112       --    for X'Address use Y'Address
3113
3114       --  or
3115
3116       --    Const : constant Address := expr;
3117       --    ...
3118       --    for X'Address use Const;
3119
3120       --  In the second case, the expr is either Y'Address, or recursively a
3121       --  constant that eventually references Y'Address.
3122
3123       Ent := Empty;
3124       Off := False;
3125
3126       if Nkind (N) = N_Attribute_Definition_Clause
3127         and then Chars (N) = Name_Address
3128       then
3129          Expr := Expression (N);
3130
3131          --  This loop checks the form of the expression for Y'Address,
3132          --  using recursion to deal with intermediate constants.
3133
3134          loop
3135             --  Check for Y'Address
3136
3137             if Nkind (Expr) = N_Attribute_Reference
3138               and then Attribute_Name (Expr) = Name_Address
3139             then
3140                Expr := Prefix (Expr);
3141                exit;
3142
3143                --  Check for Const where Const is a constant entity
3144
3145             elsif Is_Entity_Name (Expr)
3146               and then Ekind (Entity (Expr)) = E_Constant
3147             then
3148                Expr := Constant_Value (Entity (Expr));
3149
3150             --  Anything else does not need checking
3151
3152             else
3153                return;
3154             end if;
3155          end loop;
3156
3157          --  This loop checks the form of the prefix for an entity,
3158          --  using recursion to deal with intermediate components.
3159
3160          loop
3161             --  Check for Y where Y is an entity
3162
3163             if Is_Entity_Name (Expr) then
3164                Ent := Entity (Expr);
3165                return;
3166
3167             --  Check for components
3168
3169             elsif
3170                Nkind_In (Expr, N_Selected_Component, N_Indexed_Component) then
3171
3172                Expr := Prefix (Expr);
3173                Off := True;
3174
3175             --  Anything else does not need checking
3176
3177             else
3178                return;
3179             end if;
3180          end loop;
3181       end if;
3182    end Find_Overlaid_Entity;
3183
3184    -------------------------
3185    -- Find_Parameter_Type --
3186    -------------------------
3187
3188    function Find_Parameter_Type (Param : Node_Id) return Entity_Id is
3189    begin
3190       if Nkind (Param) /= N_Parameter_Specification then
3191          return Empty;
3192
3193       --  For an access parameter, obtain the type from the formal entity
3194       --  itself, because access to subprogram nodes do not carry a type.
3195       --  Shouldn't we always use the formal entity ???
3196
3197       elsif Nkind (Parameter_Type (Param)) = N_Access_Definition then
3198          return Etype (Defining_Identifier (Param));
3199
3200       else
3201          return Etype (Parameter_Type (Param));
3202       end if;
3203    end Find_Parameter_Type;
3204
3205    -----------------------------
3206    -- Find_Static_Alternative --
3207    -----------------------------
3208
3209    function Find_Static_Alternative (N : Node_Id) return Node_Id is
3210       Expr   : constant Node_Id := Expression (N);
3211       Val    : constant Uint    := Expr_Value (Expr);
3212       Alt    : Node_Id;
3213       Choice : Node_Id;
3214
3215    begin
3216       Alt := First (Alternatives (N));
3217
3218       Search : loop
3219          if Nkind (Alt) /= N_Pragma then
3220             Choice := First (Discrete_Choices (Alt));
3221             while Present (Choice) loop
3222
3223                --  Others choice, always matches
3224
3225                if Nkind (Choice) = N_Others_Choice then
3226                   exit Search;
3227
3228                --  Range, check if value is in the range
3229
3230                elsif Nkind (Choice) = N_Range then
3231                   exit Search when
3232                     Val >= Expr_Value (Low_Bound (Choice))
3233                       and then
3234                     Val <= Expr_Value (High_Bound (Choice));
3235
3236                --  Choice is a subtype name. Note that we know it must
3237                --  be a static subtype, since otherwise it would have
3238                --  been diagnosed as illegal.
3239
3240                elsif Is_Entity_Name (Choice)
3241                  and then Is_Type (Entity (Choice))
3242                then
3243                   exit Search when Is_In_Range (Expr, Etype (Choice),
3244                                                 Assume_Valid => False);
3245
3246                --  Choice is a subtype indication
3247
3248                elsif Nkind (Choice) = N_Subtype_Indication then
3249                   declare
3250                      C : constant Node_Id := Constraint (Choice);
3251                      R : constant Node_Id := Range_Expression (C);
3252
3253                   begin
3254                      exit Search when
3255                        Val >= Expr_Value (Low_Bound (R))
3256                          and then
3257                        Val <= Expr_Value (High_Bound (R));
3258                   end;
3259
3260                --  Choice is a simple expression
3261
3262                else
3263                   exit Search when Val = Expr_Value (Choice);
3264                end if;
3265
3266                Next (Choice);
3267             end loop;
3268          end if;
3269
3270          Next (Alt);
3271          pragma Assert (Present (Alt));
3272       end loop Search;
3273
3274       --  The above loop *must* terminate by finding a match, since
3275       --  we know the case statement is valid, and the value of the
3276       --  expression is known at compile time. When we fall out of
3277       --  the loop, Alt points to the alternative that we know will
3278       --  be selected at run time.
3279
3280       return Alt;
3281    end Find_Static_Alternative;
3282
3283    ------------------
3284    -- First_Actual --
3285    ------------------
3286
3287    function First_Actual (Node : Node_Id) return Node_Id is
3288       N : Node_Id;
3289
3290    begin
3291       if No (Parameter_Associations (Node)) then
3292          return Empty;
3293       end if;
3294
3295       N := First (Parameter_Associations (Node));
3296
3297       if Nkind (N) = N_Parameter_Association then
3298          return First_Named_Actual (Node);
3299       else
3300          return N;
3301       end if;
3302    end First_Actual;
3303
3304    -------------------------
3305    -- Full_Qualified_Name --
3306    -------------------------
3307
3308    function Full_Qualified_Name (E : Entity_Id) return String_Id is
3309       Res : String_Id;
3310       pragma Warnings (Off, Res);
3311
3312       function Internal_Full_Qualified_Name (E : Entity_Id) return String_Id;
3313       --  Compute recursively the qualified name without NUL at the end
3314
3315       ----------------------------------
3316       -- Internal_Full_Qualified_Name --
3317       ----------------------------------
3318
3319       function Internal_Full_Qualified_Name (E : Entity_Id) return String_Id is
3320          Ent         : Entity_Id := E;
3321          Parent_Name : String_Id := No_String;
3322
3323       begin
3324          --  Deals properly with child units
3325
3326          if Nkind (Ent) = N_Defining_Program_Unit_Name then
3327             Ent := Defining_Identifier (Ent);
3328          end if;
3329
3330          --  Compute qualification recursively (only "Standard" has no scope)
3331
3332          if Present (Scope (Scope (Ent))) then
3333             Parent_Name := Internal_Full_Qualified_Name (Scope (Ent));
3334          end if;
3335
3336          --  Every entity should have a name except some expanded blocks
3337          --  don't bother about those.
3338
3339          if Chars (Ent) = No_Name then
3340             return Parent_Name;
3341          end if;
3342
3343          --  Add a period between Name and qualification
3344
3345          if Parent_Name /= No_String then
3346             Start_String (Parent_Name);
3347             Store_String_Char (Get_Char_Code ('.'));
3348
3349          else
3350             Start_String;
3351          end if;
3352
3353          --  Generates the entity name in upper case
3354
3355          Get_Decoded_Name_String (Chars (Ent));
3356          Set_All_Upper_Case;
3357          Store_String_Chars (Name_Buffer (1 .. Name_Len));
3358          return End_String;
3359       end Internal_Full_Qualified_Name;
3360
3361    --  Start of processing for Full_Qualified_Name
3362
3363    begin
3364       Res := Internal_Full_Qualified_Name (E);
3365       Store_String_Char (Get_Char_Code (ASCII.NUL));
3366       return End_String;
3367    end Full_Qualified_Name;
3368
3369    -----------------------
3370    -- Gather_Components --
3371    -----------------------
3372
3373    procedure Gather_Components
3374      (Typ           : Entity_Id;
3375       Comp_List     : Node_Id;
3376       Governed_By   : List_Id;
3377       Into          : Elist_Id;
3378       Report_Errors : out Boolean)
3379    is
3380       Assoc           : Node_Id;
3381       Variant         : Node_Id;
3382       Discrete_Choice : Node_Id;
3383       Comp_Item       : Node_Id;
3384
3385       Discrim       : Entity_Id;
3386       Discrim_Name  : Node_Id;
3387       Discrim_Value : Node_Id;
3388
3389    begin
3390       Report_Errors := False;
3391
3392       if No (Comp_List) or else Null_Present (Comp_List) then
3393          return;
3394
3395       elsif Present (Component_Items (Comp_List)) then
3396          Comp_Item := First (Component_Items (Comp_List));
3397
3398       else
3399          Comp_Item := Empty;
3400       end if;
3401
3402       while Present (Comp_Item) loop
3403
3404          --  Skip the tag of a tagged record, the interface tags, as well
3405          --  as all items that are not user components (anonymous types,
3406          --  rep clauses, Parent field, controller field).
3407
3408          if Nkind (Comp_Item) = N_Component_Declaration then
3409             declare
3410                Comp : constant Entity_Id := Defining_Identifier (Comp_Item);
3411             begin
3412                if not Is_Tag (Comp)
3413                  and then Chars (Comp) /= Name_uParent
3414                  and then Chars (Comp) /= Name_uController
3415                then
3416                   Append_Elmt (Comp, Into);
3417                end if;
3418             end;
3419          end if;
3420
3421          Next (Comp_Item);
3422       end loop;
3423
3424       if No (Variant_Part (Comp_List)) then
3425          return;
3426       else
3427          Discrim_Name := Name (Variant_Part (Comp_List));
3428          Variant := First_Non_Pragma (Variants (Variant_Part (Comp_List)));
3429       end if;
3430
3431       --  Look for the discriminant that governs this variant part.
3432       --  The discriminant *must* be in the Governed_By List
3433
3434       Assoc := First (Governed_By);
3435       Find_Constraint : loop
3436          Discrim := First (Choices (Assoc));
3437          exit Find_Constraint when Chars (Discrim_Name) = Chars (Discrim)
3438            or else (Present (Corresponding_Discriminant (Entity (Discrim)))
3439                       and then
3440                     Chars (Corresponding_Discriminant (Entity (Discrim)))
3441                          = Chars  (Discrim_Name))
3442            or else Chars (Original_Record_Component (Entity (Discrim)))
3443                          = Chars (Discrim_Name);
3444
3445          if No (Next (Assoc)) then
3446             if not Is_Constrained (Typ)
3447               and then Is_Derived_Type (Typ)
3448               and then Present (Stored_Constraint (Typ))
3449             then
3450                --  If the type is a tagged type with inherited discriminants,
3451                --  use the stored constraint on the parent in order to find
3452                --  the values of discriminants that are otherwise hidden by an
3453                --  explicit constraint. Renamed discriminants are handled in
3454                --  the code above.
3455
3456                --  If several parent discriminants are renamed by a single
3457                --  discriminant of the derived type, the call to obtain the
3458                --  Corresponding_Discriminant field only retrieves the last
3459                --  of them. We recover the constraint on the others from the
3460                --  Stored_Constraint as well.
3461
3462                declare
3463                   D : Entity_Id;
3464                   C : Elmt_Id;
3465
3466                begin
3467                   D := First_Discriminant (Etype (Typ));
3468                   C := First_Elmt (Stored_Constraint (Typ));
3469                   while Present (D) and then Present (C) loop
3470                      if Chars (Discrim_Name) = Chars (D) then
3471                         if Is_Entity_Name (Node (C))
3472                           and then Entity (Node (C)) = Entity (Discrim)
3473                         then
3474                            --  D is renamed by Discrim, whose value is given in
3475                            --  Assoc.
3476
3477                            null;
3478
3479                         else
3480                            Assoc :=
3481                              Make_Component_Association (Sloc (Typ),
3482                                New_List
3483                                  (New_Occurrence_Of (D, Sloc (Typ))),
3484                                   Duplicate_Subexpr_No_Checks (Node (C)));
3485                         end if;
3486                         exit Find_Constraint;
3487                      end if;
3488
3489                      Next_Discriminant (D);
3490                      Next_Elmt (C);
3491                   end loop;
3492                end;
3493             end if;
3494          end if;
3495
3496          if No (Next (Assoc)) then
3497             Error_Msg_NE (" missing value for discriminant&",
3498               First (Governed_By), Discrim_Name);
3499             Report_Errors := True;
3500             return;
3501          end if;
3502
3503          Next (Assoc);
3504       end loop Find_Constraint;
3505
3506       Discrim_Value := Expression (Assoc);
3507
3508       if not Is_OK_Static_Expression (Discrim_Value) then
3509          Error_Msg_FE
3510            ("value for discriminant & must be static!",
3511             Discrim_Value, Discrim);
3512          Why_Not_Static (Discrim_Value);
3513          Report_Errors := True;
3514          return;
3515       end if;
3516
3517       Search_For_Discriminant_Value : declare
3518          Low  : Node_Id;
3519          High : Node_Id;
3520
3521          UI_High          : Uint;
3522          UI_Low           : Uint;
3523          UI_Discrim_Value : constant Uint := Expr_Value (Discrim_Value);
3524
3525       begin
3526          Find_Discrete_Value : while Present (Variant) loop
3527             Discrete_Choice := First (Discrete_Choices (Variant));
3528             while Present (Discrete_Choice) loop
3529
3530                exit Find_Discrete_Value when
3531                  Nkind (Discrete_Choice) = N_Others_Choice;
3532
3533                Get_Index_Bounds (Discrete_Choice, Low, High);
3534
3535                UI_Low  := Expr_Value (Low);
3536                UI_High := Expr_Value (High);
3537
3538                exit Find_Discrete_Value when
3539                  UI_Low <= UI_Discrim_Value
3540                    and then
3541                  UI_High >= UI_Discrim_Value;
3542
3543                Next (Discrete_Choice);
3544             end loop;
3545
3546             Next_Non_Pragma (Variant);
3547          end loop Find_Discrete_Value;
3548       end Search_For_Discriminant_Value;
3549
3550       if No (Variant) then
3551          Error_Msg_NE
3552            ("value of discriminant & is out of range", Discrim_Value, Discrim);
3553          Report_Errors := True;
3554          return;
3555       end  if;
3556
3557       --  If we have found the corresponding choice, recursively add its
3558       --  components to the Into list.
3559
3560       Gather_Components (Empty,
3561         Component_List (Variant), Governed_By, Into, Report_Errors);
3562    end Gather_Components;
3563
3564    ------------------------
3565    -- Get_Actual_Subtype --
3566    ------------------------
3567
3568    function Get_Actual_Subtype (N : Node_Id) return Entity_Id is
3569       Typ  : constant Entity_Id := Etype (N);
3570       Utyp : Entity_Id := Underlying_Type (Typ);
3571       Decl : Node_Id;
3572       Atyp : Entity_Id;
3573
3574    begin
3575       if No (Utyp) then
3576          Utyp := Typ;
3577       end if;
3578
3579       --  If what we have is an identifier that references a subprogram
3580       --  formal, or a variable or constant object, then we get the actual
3581       --  subtype from the referenced entity if one has been built.
3582
3583       if Nkind (N) = N_Identifier
3584         and then
3585           (Is_Formal (Entity (N))
3586             or else Ekind (Entity (N)) = E_Constant
3587             or else Ekind (Entity (N)) = E_Variable)
3588         and then Present (Actual_Subtype (Entity (N)))
3589       then
3590          return Actual_Subtype (Entity (N));
3591
3592       --  Actual subtype of unchecked union is always itself. We never need
3593       --  the "real" actual subtype. If we did, we couldn't get it anyway
3594       --  because the discriminant is not available. The restrictions on
3595       --  Unchecked_Union are designed to make sure that this is OK.
3596
3597       elsif Is_Unchecked_Union (Base_Type (Utyp)) then
3598          return Typ;
3599
3600       --  Here for the unconstrained case, we must find actual subtype
3601       --  No actual subtype is available, so we must build it on the fly.
3602
3603       --  Checking the type, not the underlying type, for constrainedness
3604       --  seems to be necessary. Maybe all the tests should be on the type???
3605
3606       elsif (not Is_Constrained (Typ))
3607            and then (Is_Array_Type (Utyp)
3608                       or else (Is_Record_Type (Utyp)
3609                                 and then Has_Discriminants (Utyp)))
3610            and then not Has_Unknown_Discriminants (Utyp)
3611            and then not (Ekind (Utyp) = E_String_Literal_Subtype)
3612       then
3613          --  Nothing to do if in spec expression (why not???)
3614
3615          if In_Spec_Expression then
3616             return Typ;
3617
3618          elsif Is_Private_Type (Typ)
3619            and then not Has_Discriminants (Typ)
3620          then
3621             --  If the type has no discriminants, there is no subtype to
3622             --  build, even if the underlying type is discriminated.
3623
3624             return Typ;
3625
3626          --  Else build the actual subtype
3627
3628          else
3629             Decl := Build_Actual_Subtype (Typ, N);
3630             Atyp := Defining_Identifier (Decl);
3631
3632             --  If Build_Actual_Subtype generated a new declaration then use it
3633
3634             if Atyp /= Typ then
3635
3636                --  The actual subtype is an Itype, so analyze the declaration,
3637                --  but do not attach it to the tree, to get the type defined.
3638
3639                Set_Parent (Decl, N);
3640                Set_Is_Itype (Atyp);
3641                Analyze (Decl, Suppress => All_Checks);
3642                Set_Associated_Node_For_Itype (Atyp, N);
3643                Set_Has_Delayed_Freeze (Atyp, False);
3644
3645                --  We need to freeze the actual subtype immediately. This is
3646                --  needed, because otherwise this Itype will not get frozen
3647                --  at all, and it is always safe to freeze on creation because
3648                --  any associated types must be frozen at this point.
3649
3650                Freeze_Itype (Atyp, N);
3651                return Atyp;
3652
3653             --  Otherwise we did not build a declaration, so return original
3654
3655             else
3656                return Typ;
3657             end if;
3658          end if;
3659
3660       --  For all remaining cases, the actual subtype is the same as
3661       --  the nominal type.
3662
3663       else
3664          return Typ;
3665       end if;
3666    end Get_Actual_Subtype;
3667
3668    -------------------------------------
3669    -- Get_Actual_Subtype_If_Available --
3670    -------------------------------------
3671
3672    function Get_Actual_Subtype_If_Available (N : Node_Id) return Entity_Id is
3673       Typ  : constant Entity_Id := Etype (N);
3674
3675    begin
3676       --  If what we have is an identifier that references a subprogram
3677       --  formal, or a variable or constant object, then we get the actual
3678       --  subtype from the referenced entity if one has been built.
3679
3680       if Nkind (N) = N_Identifier
3681         and then
3682           (Is_Formal (Entity (N))
3683             or else Ekind (Entity (N)) = E_Constant
3684             or else Ekind (Entity (N)) = E_Variable)
3685         and then Present (Actual_Subtype (Entity (N)))
3686       then
3687          return Actual_Subtype (Entity (N));
3688
3689       --  Otherwise the Etype of N is returned unchanged
3690
3691       else
3692          return Typ;
3693       end if;
3694    end Get_Actual_Subtype_If_Available;
3695
3696    -------------------------------
3697    -- Get_Default_External_Name --
3698    -------------------------------
3699
3700    function Get_Default_External_Name (E : Node_Or_Entity_Id) return Node_Id is
3701    begin
3702       Get_Decoded_Name_String (Chars (E));
3703
3704       if Opt.External_Name_Imp_Casing = Uppercase then
3705          Set_Casing (All_Upper_Case);
3706       else
3707          Set_Casing (All_Lower_Case);
3708       end if;
3709
3710       return
3711         Make_String_Literal (Sloc (E),
3712           Strval => String_From_Name_Buffer);
3713    end Get_Default_External_Name;
3714
3715    ---------------------------
3716    -- Get_Enum_Lit_From_Pos --
3717    ---------------------------
3718
3719    function Get_Enum_Lit_From_Pos
3720      (T   : Entity_Id;
3721       Pos : Uint;
3722       Loc : Source_Ptr) return Node_Id
3723    is
3724       Lit : Node_Id;
3725
3726    begin
3727       --  In the case where the literal is of type Character, Wide_Character
3728       --  or Wide_Wide_Character or of a type derived from them, there needs
3729       --  to be some special handling since there is no explicit chain of
3730       --  literals to search. Instead, an N_Character_Literal node is created
3731       --  with the appropriate Char_Code and Chars fields.
3732
3733       if Is_Standard_Character_Type (T) then
3734          Set_Character_Literal_Name (UI_To_CC (Pos));
3735          return
3736            Make_Character_Literal (Loc,
3737              Chars              => Name_Find,
3738              Char_Literal_Value => Pos);
3739
3740       --  For all other cases, we have a complete table of literals, and
3741       --  we simply iterate through the chain of literal until the one
3742       --  with the desired position value is found.
3743       --
3744
3745       else
3746          Lit := First_Literal (Base_Type (T));
3747          for J in 1 .. UI_To_Int (Pos) loop
3748             Next_Literal (Lit);
3749          end loop;
3750
3751          return New_Occurrence_Of (Lit, Loc);
3752       end if;
3753    end Get_Enum_Lit_From_Pos;
3754
3755    ------------------------
3756    -- Get_Generic_Entity --
3757    ------------------------
3758
3759    function Get_Generic_Entity (N : Node_Id) return Entity_Id is
3760       Ent : constant Entity_Id := Entity (Name (N));
3761    begin
3762       if Present (Renamed_Object (Ent)) then
3763          return Renamed_Object (Ent);
3764       else
3765          return Ent;
3766       end if;
3767    end Get_Generic_Entity;
3768
3769    ----------------------
3770    -- Get_Index_Bounds --
3771    ----------------------
3772
3773    procedure Get_Index_Bounds (N : Node_Id; L, H : out Node_Id) is
3774       Kind : constant Node_Kind := Nkind (N);
3775       R    : Node_Id;
3776
3777    begin
3778       if Kind = N_Range then
3779          L := Low_Bound (N);
3780          H := High_Bound (N);
3781
3782       elsif Kind = N_Subtype_Indication then
3783          R := Range_Expression (Constraint (N));
3784
3785          if R = Error then
3786             L := Error;
3787             H := Error;
3788             return;
3789
3790          else
3791             L := Low_Bound  (Range_Expression (Constraint (N)));
3792             H := High_Bound (Range_Expression (Constraint (N)));
3793          end if;
3794
3795       elsif Is_Entity_Name (N) and then Is_Type (Entity (N)) then
3796          if Error_Posted (Scalar_Range (Entity (N))) then
3797             L := Error;
3798             H := Error;
3799
3800          elsif Nkind (Scalar_Range (Entity (N))) = N_Subtype_Indication then
3801             Get_Index_Bounds (Scalar_Range (Entity (N)), L, H);
3802
3803          else
3804             L := Low_Bound  (Scalar_Range (Entity (N)));
3805             H := High_Bound (Scalar_Range (Entity (N)));
3806          end if;
3807
3808       else
3809          --  N is an expression, indicating a range with one value
3810
3811          L := N;
3812          H := N;
3813       end if;
3814    end Get_Index_Bounds;
3815
3816    ----------------------------------
3817    -- Get_Library_Unit_Name_string --
3818    ----------------------------------
3819
3820    procedure Get_Library_Unit_Name_String (Decl_Node : Node_Id) is
3821       Unit_Name_Id : constant Unit_Name_Type := Get_Unit_Name (Decl_Node);
3822
3823    begin
3824       Get_Unit_Name_String (Unit_Name_Id);
3825
3826       --  Remove seven last character (" (spec)" or " (body)")
3827
3828       Name_Len := Name_Len - 7;
3829       pragma Assert (Name_Buffer (Name_Len + 1) = ' ');
3830    end Get_Library_Unit_Name_String;
3831
3832    ------------------------
3833    -- Get_Name_Entity_Id --
3834    ------------------------
3835
3836    function Get_Name_Entity_Id (Id : Name_Id) return Entity_Id is
3837    begin
3838       return Entity_Id (Get_Name_Table_Info (Id));
3839    end Get_Name_Entity_Id;
3840
3841    -------------------
3842    -- Get_Pragma_Id --
3843    -------------------
3844
3845    function Get_Pragma_Id (N : Node_Id) return Pragma_Id is
3846    begin
3847       return Get_Pragma_Id (Pragma_Name (N));
3848    end Get_Pragma_Id;
3849
3850    ---------------------------
3851    -- Get_Referenced_Object --
3852    ---------------------------
3853
3854    function Get_Referenced_Object (N : Node_Id) return Node_Id is
3855       R : Node_Id;
3856
3857    begin
3858       R := N;
3859       while Is_Entity_Name (R)
3860         and then Present (Renamed_Object (Entity (R)))
3861       loop
3862          R := Renamed_Object (Entity (R));
3863       end loop;
3864
3865       return R;
3866    end Get_Referenced_Object;
3867
3868    ------------------------
3869    -- Get_Renamed_Entity --
3870    ------------------------
3871
3872    function Get_Renamed_Entity (E : Entity_Id) return Entity_Id is
3873       R : Entity_Id;
3874
3875    begin
3876       R := E;
3877       while Present (Renamed_Entity (R)) loop
3878          R := Renamed_Entity (R);
3879       end loop;
3880
3881       return R;
3882    end Get_Renamed_Entity;
3883
3884    -------------------------
3885    -- Get_Subprogram_Body --
3886    -------------------------
3887
3888    function Get_Subprogram_Body (E : Entity_Id) return Node_Id is
3889       Decl : Node_Id;
3890
3891    begin
3892       Decl := Unit_Declaration_Node (E);
3893
3894       if Nkind (Decl) = N_Subprogram_Body then
3895          return Decl;
3896
3897       --  The below comment is bad, because it is possible for
3898       --  Nkind (Decl) to be an N_Subprogram_Body_Stub ???
3899
3900       else           --  Nkind (Decl) = N_Subprogram_Declaration
3901
3902          if Present (Corresponding_Body (Decl)) then
3903             return Unit_Declaration_Node (Corresponding_Body (Decl));
3904
3905          --  Imported subprogram case
3906
3907          else
3908             return Empty;
3909          end if;
3910       end if;
3911    end Get_Subprogram_Body;
3912
3913    ---------------------------
3914    -- Get_Subprogram_Entity --
3915    ---------------------------
3916
3917    function Get_Subprogram_Entity (Nod : Node_Id) return Entity_Id is
3918       Nam  : Node_Id;
3919       Proc : Entity_Id;
3920
3921    begin
3922       if Nkind (Nod) = N_Accept_Statement then
3923          Nam := Entry_Direct_Name (Nod);
3924
3925       --  For an entry call, the prefix of the call is a selected component.
3926       --  Need additional code for internal calls ???
3927
3928       elsif Nkind (Nod) = N_Entry_Call_Statement then
3929          if Nkind (Name (Nod)) = N_Selected_Component then
3930             Nam := Entity (Selector_Name (Name (Nod)));
3931          else
3932             Nam := Empty;
3933          end if;
3934
3935       else
3936          Nam := Name (Nod);
3937       end if;
3938
3939       if Nkind (Nam) = N_Explicit_Dereference then
3940          Proc := Etype (Prefix (Nam));
3941       elsif Is_Entity_Name (Nam) then
3942          Proc := Entity (Nam);
3943       else
3944          return Empty;
3945       end if;
3946
3947       if Is_Object (Proc) then
3948          Proc := Etype (Proc);
3949       end if;
3950
3951       if Ekind (Proc) = E_Access_Subprogram_Type then
3952          Proc := Directly_Designated_Type (Proc);
3953       end if;
3954
3955       if not Is_Subprogram (Proc)
3956         and then Ekind (Proc) /= E_Subprogram_Type
3957       then
3958          return Empty;
3959       else
3960          return Proc;
3961       end if;
3962    end Get_Subprogram_Entity;
3963
3964    -----------------------------
3965    -- Get_Task_Body_Procedure --
3966    -----------------------------
3967
3968    function Get_Task_Body_Procedure (E : Entity_Id) return Node_Id is
3969    begin
3970       --  Note: A task type may be the completion of a private type with
3971       --  discriminants. When performing elaboration checks on a task
3972       --  declaration, the current view of the type may be the private one,
3973       --  and the procedure that holds the body of the task is held in its
3974       --  underlying type.
3975
3976       --  This is an odd function, why not have Task_Body_Procedure do
3977       --  the following digging???
3978
3979       return Task_Body_Procedure (Underlying_Type (Root_Type (E)));
3980    end Get_Task_Body_Procedure;
3981
3982    -----------------------
3983    -- Has_Access_Values --
3984    -----------------------
3985
3986    function Has_Access_Values (T : Entity_Id) return Boolean is
3987       Typ : constant Entity_Id := Underlying_Type (T);
3988
3989    begin
3990       --  Case of a private type which is not completed yet. This can only
3991       --  happen in the case of a generic format type appearing directly, or
3992       --  as a component of the type to which this function is being applied
3993       --  at the top level. Return False in this case, since we certainly do
3994       --  not know that the type contains access types.
3995
3996       if No (Typ) then
3997          return False;
3998
3999       elsif Is_Access_Type (Typ) then
4000          return True;
4001
4002       elsif Is_Array_Type (Typ) then
4003          return Has_Access_Values (Component_Type (Typ));
4004
4005       elsif Is_Record_Type (Typ) then
4006          declare
4007             Comp : Entity_Id;
4008
4009          begin
4010             --  Loop to Check components
4011
4012             Comp := First_Component_Or_Discriminant (Typ);
4013             while Present (Comp) loop
4014
4015                --  Check for access component, tag field does not count, even
4016                --  though it is implemented internally using an access type.
4017
4018                if Has_Access_Values (Etype (Comp))
4019                  and then Chars (Comp) /= Name_uTag
4020                then
4021                   return True;
4022                end if;
4023
4024                Next_Component_Or_Discriminant (Comp);
4025             end loop;
4026          end;
4027
4028          return False;
4029
4030       else
4031          return False;
4032       end if;
4033    end Has_Access_Values;
4034
4035    ------------------------------
4036    -- Has_Compatible_Alignment --
4037    ------------------------------
4038
4039    function Has_Compatible_Alignment
4040      (Obj  : Entity_Id;
4041       Expr : Node_Id) return Alignment_Result
4042    is
4043       function Has_Compatible_Alignment_Internal
4044         (Obj     : Entity_Id;
4045          Expr    : Node_Id;
4046          Default : Alignment_Result) return Alignment_Result;
4047       --  This is the internal recursive function that actually does the work.
4048       --  There is one additional parameter, which says what the result should
4049       --  be if no alignment information is found, and there is no definite
4050       --  indication of compatible alignments. At the outer level, this is set
4051       --  to Unknown, but for internal recursive calls in the case where types
4052       --  are known to be correct, it is set to Known_Compatible.
4053
4054       ---------------------------------------
4055       -- Has_Compatible_Alignment_Internal --
4056       ---------------------------------------
4057
4058       function Has_Compatible_Alignment_Internal
4059         (Obj     : Entity_Id;
4060          Expr    : Node_Id;
4061          Default : Alignment_Result) return Alignment_Result
4062       is
4063          Result : Alignment_Result := Known_Compatible;
4064          --  Holds the current status of the result. Note that once a value of
4065          --  Known_Incompatible is set, it is sticky and does not get changed
4066          --  to Unknown (the value in Result only gets worse as we go along,
4067          --  never better).
4068
4069          Offs : Uint := No_Uint;
4070          --  Set to a factor of the offset from the base object when Expr is a
4071          --  selected or indexed component, based on Component_Bit_Offset and
4072          --  Component_Size respectively. A negative value is used to represent
4073          --  a value which is not known at compile time.
4074
4075          procedure Check_Prefix;
4076          --  Checks the prefix recursively in the case where the expression
4077          --  is an indexed or selected component.
4078
4079          procedure Set_Result (R : Alignment_Result);
4080          --  If R represents a worse outcome (unknown instead of known
4081          --  compatible, or known incompatible), then set Result to R.
4082
4083          ------------------
4084          -- Check_Prefix --
4085          ------------------
4086
4087          procedure Check_Prefix is
4088          begin
4089             --  The subtlety here is that in doing a recursive call to check
4090             --  the prefix, we have to decide what to do in the case where we
4091             --  don't find any specific indication of an alignment problem.
4092
4093             --  At the outer level, we normally set Unknown as the result in
4094             --  this case, since we can only set Known_Compatible if we really
4095             --  know that the alignment value is OK, but for the recursive
4096             --  call, in the case where the types match, and we have not
4097             --  specified a peculiar alignment for the object, we are only
4098             --  concerned about suspicious rep clauses, the default case does
4099             --  not affect us, since the compiler will, in the absence of such
4100             --  rep clauses, ensure that the alignment is correct.
4101
4102             if Default = Known_Compatible
4103               or else
4104                 (Etype (Obj) = Etype (Expr)
4105                   and then (Unknown_Alignment (Obj)
4106                              or else
4107                                Alignment (Obj) = Alignment (Etype (Obj))))
4108             then
4109                Set_Result
4110                  (Has_Compatible_Alignment_Internal
4111                     (Obj, Prefix (Expr), Known_Compatible));
4112
4113             --  In all other cases, we need a full check on the prefix
4114
4115             else
4116                Set_Result
4117                  (Has_Compatible_Alignment_Internal
4118                     (Obj, Prefix (Expr), Unknown));
4119             end if;
4120          end Check_Prefix;
4121
4122          ----------------
4123          -- Set_Result --
4124          ----------------
4125
4126          procedure Set_Result (R : Alignment_Result) is
4127          begin
4128             if R > Result then
4129                Result := R;
4130             end if;
4131          end Set_Result;
4132
4133       --  Start of processing for Has_Compatible_Alignment_Internal
4134
4135       begin
4136          --  If Expr is a selected component, we must make sure there is no
4137          --  potentially troublesome component clause, and that the record is
4138          --  not packed.
4139
4140          if Nkind (Expr) = N_Selected_Component then
4141
4142             --  Packed record always generate unknown alignment
4143
4144             if Is_Packed (Etype (Prefix (Expr))) then
4145                Set_Result (Unknown);
4146             end if;
4147
4148             --  Check prefix and component offset
4149
4150             Check_Prefix;
4151             Offs := Component_Bit_Offset (Entity (Selector_Name (Expr)));
4152
4153          --  If Expr is an indexed component, we must make sure there is no
4154          --  potentially troublesome Component_Size clause and that the array
4155          --  is not bit-packed.
4156
4157          elsif Nkind (Expr) = N_Indexed_Component then
4158             declare
4159                Typ : constant Entity_Id := Etype (Prefix (Expr));
4160                Ind : constant Node_Id   := First_Index (Typ);
4161
4162             begin
4163                --  Bit packed array always generates unknown alignment
4164
4165                if Is_Bit_Packed_Array (Typ) then
4166                   Set_Result (Unknown);
4167                end if;
4168
4169                --  Check prefix and component offset
4170
4171                Check_Prefix;
4172                Offs := Component_Size (Typ);
4173
4174                --  Small optimization: compute the full offset when possible
4175
4176                if Offs /= No_Uint
4177                  and then Offs > Uint_0
4178                  and then Present (Ind)
4179                  and then Nkind (Ind) = N_Range
4180                  and then Compile_Time_Known_Value (Low_Bound (Ind))
4181                  and then Compile_Time_Known_Value (First (Expressions (Expr)))
4182                then
4183                   Offs := Offs * (Expr_Value (First (Expressions (Expr)))
4184                                     - Expr_Value (Low_Bound ((Ind))));
4185                end if;
4186             end;
4187          end if;
4188
4189          --  If we have a null offset, the result is entirely determined by
4190          --  the base object and has already been computed recursively.
4191
4192          if Offs = Uint_0 then
4193             null;
4194
4195          --  Case where we know the alignment of the object
4196
4197          elsif Known_Alignment (Obj) then
4198             declare
4199                ObjA : constant Uint := Alignment (Obj);
4200                ExpA : Uint          := No_Uint;
4201                SizA : Uint          := No_Uint;
4202
4203             begin
4204                --  If alignment of Obj is 1, then we are always OK
4205
4206                if ObjA = 1 then
4207                   Set_Result (Known_Compatible);
4208
4209                --  Alignment of Obj is greater than 1, so we need to check
4210
4211                else
4212                   --  If we have an offset, see if it is compatible
4213
4214                   if Offs /= No_Uint and Offs > Uint_0 then
4215                      if Offs mod (System_Storage_Unit * ObjA) /= 0 then
4216                         Set_Result (Known_Incompatible);
4217                      end if;
4218
4219                      --  See if Expr is an object with known alignment
4220
4221                   elsif Is_Entity_Name (Expr)
4222                     and then Known_Alignment (Entity (Expr))
4223                   then
4224                      ExpA := Alignment (Entity (Expr));
4225
4226                      --  Otherwise, we can use the alignment of the type of
4227                      --  Expr given that we already checked for
4228                      --  discombobulating rep clauses for the cases of indexed
4229                      --  and selected components above.
4230
4231                   elsif Known_Alignment (Etype (Expr)) then
4232                      ExpA := Alignment (Etype (Expr));
4233
4234                      --  Otherwise the alignment is unknown
4235
4236                   else
4237                      Set_Result (Default);
4238                   end if;
4239
4240                   --  If we got an alignment, see if it is acceptable
4241
4242                   if ExpA /= No_Uint and then ExpA < ObjA then
4243                      Set_Result (Known_Incompatible);
4244                   end if;
4245
4246                   --  If Expr is not a piece of a larger object, see if size
4247                   --  is given. If so, check that it is not too small for the
4248                   --  required alignment.
4249
4250                   if Offs /= No_Uint then
4251                      null;
4252
4253                      --  See if Expr is an object with known size
4254
4255                   elsif Is_Entity_Name (Expr)
4256                     and then Known_Static_Esize (Entity (Expr))
4257                   then
4258                      SizA := Esize (Entity (Expr));
4259
4260                      --  Otherwise, we check the object size of the Expr type
4261
4262                   elsif Known_Static_Esize (Etype (Expr)) then
4263                      SizA := Esize (Etype (Expr));
4264                   end if;
4265
4266                   --  If we got a size, see if it is a multiple of the Obj
4267                   --  alignment, if not, then the alignment cannot be
4268                   --  acceptable, since the size is always a multiple of the
4269                   --  alignment.
4270
4271                   if SizA /= No_Uint then
4272                      if SizA mod (ObjA * Ttypes.System_Storage_Unit) /= 0 then
4273                         Set_Result (Known_Incompatible);
4274                      end if;
4275                   end if;
4276                end if;
4277             end;
4278
4279          --  If we do not know required alignment, any non-zero offset is a
4280          --  potential problem (but certainly may be OK, so result is unknown).
4281
4282          elsif Offs /= No_Uint then
4283             Set_Result (Unknown);
4284
4285          --  If we can't find the result by direct comparison of alignment
4286          --  values, then there is still one case that we can determine known
4287          --  result, and that is when we can determine that the types are the
4288          --  same, and no alignments are specified. Then we known that the
4289          --  alignments are compatible, even if we don't know the alignment
4290          --  value in the front end.
4291
4292          elsif Etype (Obj) = Etype (Expr) then
4293
4294             --  Types are the same, but we have to check for possible size
4295             --  and alignments on the Expr object that may make the alignment
4296             --  different, even though the types are the same.
4297
4298             if Is_Entity_Name (Expr) then
4299
4300                --  First check alignment of the Expr object. Any alignment less
4301                --  than Maximum_Alignment is worrisome since this is the case
4302                --  where we do not know the alignment of Obj.
4303
4304                if Known_Alignment (Entity (Expr))
4305                  and then
4306                    UI_To_Int (Alignment (Entity (Expr))) <
4307                                                     Ttypes.Maximum_Alignment
4308                then
4309                   Set_Result (Unknown);
4310
4311                   --  Now check size of Expr object. Any size that is not an
4312                   --  even multiple of Maximum_Alignment is also worrisome
4313                   --  since it may cause the alignment of the object to be less
4314                   --  than the alignment of the type.
4315
4316                elsif Known_Static_Esize (Entity (Expr))
4317                  and then
4318                    (UI_To_Int (Esize (Entity (Expr))) mod
4319                      (Ttypes.Maximum_Alignment * Ttypes.System_Storage_Unit))
4320                                                                         /= 0
4321                then
4322                   Set_Result (Unknown);
4323
4324                   --  Otherwise same type is decisive
4325
4326                else
4327                   Set_Result (Known_Compatible);
4328                end if;
4329             end if;
4330
4331          --  Another case to deal with is when there is an explicit size or
4332          --  alignment clause when the types are not the same. If so, then the
4333          --  result is Unknown. We don't need to do this test if the Default is
4334          --  Unknown, since that result will be set in any case.
4335
4336          elsif Default /= Unknown
4337            and then (Has_Size_Clause      (Etype (Expr))
4338                       or else
4339                      Has_Alignment_Clause (Etype (Expr)))
4340          then
4341             Set_Result (Unknown);
4342
4343          --  If no indication found, set default
4344
4345          else
4346             Set_Result (Default);
4347          end if;
4348
4349          --  Return worst result found
4350
4351          return Result;
4352       end Has_Compatible_Alignment_Internal;
4353
4354    --  Start of processing for Has_Compatible_Alignment
4355
4356    begin
4357       --  If Obj has no specified alignment, then set alignment from the type
4358       --  alignment. Perhaps we should always do this, but for sure we should
4359       --  do it when there is an address clause since we can do more if the
4360       --  alignment is known.
4361
4362       if Unknown_Alignment (Obj) then
4363          Set_Alignment (Obj, Alignment (Etype (Obj)));
4364       end if;
4365
4366       --  Now do the internal call that does all the work
4367
4368       return Has_Compatible_Alignment_Internal (Obj, Expr, Unknown);
4369    end Has_Compatible_Alignment;
4370
4371    ----------------------
4372    -- Has_Declarations --
4373    ----------------------
4374
4375    function Has_Declarations (N : Node_Id) return Boolean is
4376    begin
4377       return Nkind_In (Nkind (N), N_Accept_Statement,
4378                                   N_Block_Statement,
4379                                   N_Compilation_Unit_Aux,
4380                                   N_Entry_Body,
4381                                   N_Package_Body,
4382                                   N_Protected_Body,
4383                                   N_Subprogram_Body,
4384                                   N_Task_Body,
4385                                   N_Package_Specification);
4386    end Has_Declarations;
4387
4388    -------------------------------------------
4389    -- Has_Discriminant_Dependent_Constraint --
4390    -------------------------------------------
4391
4392    function Has_Discriminant_Dependent_Constraint
4393      (Comp : Entity_Id) return Boolean
4394    is
4395       Comp_Decl  : constant Node_Id := Parent (Comp);
4396       Subt_Indic : constant Node_Id :=
4397                      Subtype_Indication (Component_Definition (Comp_Decl));
4398       Constr     : Node_Id;
4399       Assn       : Node_Id;
4400
4401    begin
4402       if Nkind (Subt_Indic) = N_Subtype_Indication then
4403          Constr := Constraint (Subt_Indic);
4404
4405          if Nkind (Constr) = N_Index_Or_Discriminant_Constraint then
4406             Assn := First (Constraints (Constr));
4407             while Present (Assn) loop
4408                case Nkind (Assn) is
4409                   when N_Subtype_Indication |
4410                        N_Range              |
4411                        N_Identifier
4412                   =>
4413                      if Depends_On_Discriminant (Assn) then
4414                         return True;
4415                      end if;
4416
4417                   when N_Discriminant_Association =>
4418                      if Depends_On_Discriminant (Expression (Assn)) then
4419                         return True;
4420                      end if;
4421
4422                   when others =>
4423                      null;
4424
4425                end case;
4426
4427                Next (Assn);
4428             end loop;
4429          end if;
4430       end if;
4431
4432       return False;
4433    end Has_Discriminant_Dependent_Constraint;
4434
4435    --------------------
4436    -- Has_Infinities --
4437    --------------------
4438
4439    function Has_Infinities (E : Entity_Id) return Boolean is
4440    begin
4441       return
4442         Is_Floating_Point_Type (E)
4443           and then Nkind (Scalar_Range (E)) = N_Range
4444           and then Includes_Infinities (Scalar_Range (E));
4445    end Has_Infinities;
4446
4447    --------------------
4448    -- Has_Interfaces --
4449    --------------------
4450
4451    function Has_Interfaces
4452      (T             : Entity_Id;
4453       Use_Full_View : Boolean := True) return Boolean
4454    is
4455       Typ : Entity_Id;
4456
4457    begin
4458       --  Handle concurrent types
4459
4460       if Is_Concurrent_Type (T) then
4461          Typ := Corresponding_Record_Type (T);
4462       else
4463          Typ := T;
4464       end if;
4465
4466       if not Present (Typ)
4467         or else not Is_Record_Type (Typ)
4468         or else not Is_Tagged_Type (Typ)
4469       then
4470          return False;
4471       end if;
4472
4473       --  Handle private types
4474
4475       if Use_Full_View
4476         and then Present (Full_View (Typ))
4477       then
4478          Typ := Full_View (Typ);
4479       end if;
4480
4481       --  Handle concurrent record types
4482
4483       if Is_Concurrent_Record_Type (Typ)
4484         and then Is_Non_Empty_List (Abstract_Interface_List (Typ))
4485       then
4486          return True;
4487       end if;
4488
4489       loop
4490          if Is_Interface (Typ)
4491            or else
4492              (Is_Record_Type (Typ)
4493                and then Present (Interfaces (Typ))
4494                and then not Is_Empty_Elmt_List (Interfaces (Typ)))
4495          then
4496             return True;
4497          end if;
4498
4499          exit when Etype (Typ) = Typ
4500
4501             --  Handle private types
4502
4503             or else (Present (Full_View (Etype (Typ)))
4504                        and then Full_View (Etype (Typ)) = Typ)
4505
4506             --  Protect the frontend against wrong source with cyclic
4507             --  derivations
4508
4509             or else Etype (Typ) = T;
4510
4511          --  Climb to the ancestor type handling private types
4512
4513          if Present (Full_View (Etype (Typ))) then
4514             Typ := Full_View (Etype (Typ));
4515          else
4516             Typ := Etype (Typ);
4517          end if;
4518       end loop;
4519
4520       return False;
4521    end Has_Interfaces;
4522
4523    ------------------------
4524    -- Has_Null_Exclusion --
4525    ------------------------
4526
4527    function Has_Null_Exclusion (N : Node_Id) return Boolean is
4528    begin
4529       case Nkind (N) is
4530          when N_Access_Definition               |
4531               N_Access_Function_Definition      |
4532               N_Access_Procedure_Definition     |
4533               N_Access_To_Object_Definition     |
4534               N_Allocator                       |
4535               N_Derived_Type_Definition         |
4536               N_Function_Specification          |
4537               N_Subtype_Declaration             =>
4538             return Null_Exclusion_Present (N);
4539
4540          when N_Component_Definition            |
4541               N_Formal_Object_Declaration       |
4542               N_Object_Renaming_Declaration     =>
4543             if Present (Subtype_Mark (N)) then
4544                return Null_Exclusion_Present (N);
4545             else pragma Assert (Present (Access_Definition (N)));
4546                return Null_Exclusion_Present (Access_Definition (N));
4547             end if;
4548
4549          when N_Discriminant_Specification =>
4550             if Nkind (Discriminant_Type (N)) = N_Access_Definition then
4551                return Null_Exclusion_Present (Discriminant_Type (N));
4552             else
4553                return Null_Exclusion_Present (N);
4554             end if;
4555
4556          when N_Object_Declaration =>
4557             if Nkind (Object_Definition (N)) = N_Access_Definition then
4558                return Null_Exclusion_Present (Object_Definition (N));
4559             else
4560                return Null_Exclusion_Present (N);
4561             end if;
4562
4563          when N_Parameter_Specification =>
4564             if Nkind (Parameter_Type (N)) = N_Access_Definition then
4565                return Null_Exclusion_Present (Parameter_Type (N));
4566             else
4567                return Null_Exclusion_Present (N);
4568             end if;
4569
4570          when others =>
4571             return False;
4572
4573       end case;
4574    end Has_Null_Exclusion;
4575
4576    ------------------------
4577    -- Has_Null_Extension --
4578    ------------------------
4579
4580    function Has_Null_Extension (T : Entity_Id) return Boolean is
4581       B     : constant Entity_Id := Base_Type (T);
4582       Comps : Node_Id;
4583       Ext   : Node_Id;
4584
4585    begin
4586       if Nkind (Parent (B)) = N_Full_Type_Declaration
4587         and then Present (Record_Extension_Part (Type_Definition (Parent (B))))
4588       then
4589          Ext := Record_Extension_Part (Type_Definition (Parent (B)));
4590
4591          if Present (Ext) then
4592             if Null_Present (Ext) then
4593                return True;
4594             else
4595                Comps := Component_List (Ext);
4596
4597                --  The null component list is rewritten during analysis to
4598                --  include the parent component. Any other component indicates
4599                --  that the extension was not originally null.
4600
4601                return Null_Present (Comps)
4602                  or else No (Next (First (Component_Items (Comps))));
4603             end if;
4604          else
4605             return False;
4606          end if;
4607
4608       else
4609          return False;
4610       end if;
4611    end Has_Null_Extension;
4612
4613    -------------------------------
4614    -- Has_Overriding_Initialize --
4615    -------------------------------
4616
4617    function Has_Overriding_Initialize (T : Entity_Id) return Boolean is
4618       BT   : constant Entity_Id := Base_Type (T);
4619       Comp : Entity_Id;
4620       P    : Elmt_Id;
4621
4622    begin
4623       if Is_Controlled (BT) then
4624
4625          --  For derived types, check immediate ancestor, excluding
4626          --  Controlled itself.
4627
4628          if Is_Derived_Type (BT)
4629            and then not In_Predefined_Unit (Etype (BT))
4630            and then Has_Overriding_Initialize (Etype (BT))
4631          then
4632             return True;
4633
4634          elsif Present (Primitive_Operations (BT)) then
4635             P := First_Elmt (Primitive_Operations (BT));
4636             while Present (P) loop
4637                if Chars (Node (P)) = Name_Initialize
4638                  and then Comes_From_Source (Node (P))
4639                then
4640                   return True;
4641                end if;
4642
4643                Next_Elmt (P);
4644             end loop;
4645          end if;
4646
4647          return False;
4648
4649       elsif Has_Controlled_Component (BT) then
4650          Comp := First_Component (BT);
4651          while Present (Comp) loop
4652             if Has_Overriding_Initialize (Etype (Comp)) then
4653                return True;
4654             end if;
4655
4656             Next_Component (Comp);
4657          end loop;
4658
4659          return False;
4660
4661       else
4662          return False;
4663       end if;
4664    end Has_Overriding_Initialize;
4665
4666    --------------------------------------
4667    -- Has_Preelaborable_Initialization --
4668    --------------------------------------
4669
4670    function Has_Preelaborable_Initialization (E : Entity_Id) return Boolean is
4671       Has_PE : Boolean;
4672
4673       procedure Check_Components (E : Entity_Id);
4674       --  Check component/discriminant chain, sets Has_PE False if a component
4675       --  or discriminant does not meet the preelaborable initialization rules.
4676
4677       ----------------------
4678       -- Check_Components --
4679       ----------------------
4680
4681       procedure Check_Components (E : Entity_Id) is
4682          Ent : Entity_Id;
4683          Exp : Node_Id;
4684
4685          function Is_Preelaborable_Expression (N : Node_Id) return Boolean;
4686          --  Returns True if and only if the expression denoted by N does not
4687          --  violate restrictions on preelaborable constructs (RM-10.2.1(5-9)).
4688
4689          ---------------------------------
4690          -- Is_Preelaborable_Expression --
4691          ---------------------------------
4692
4693          function Is_Preelaborable_Expression (N : Node_Id) return Boolean is
4694             Exp           : Node_Id;
4695             Assn          : Node_Id;
4696             Choice        : Node_Id;
4697             Comp_Type     : Entity_Id;
4698             Is_Array_Aggr : Boolean;
4699
4700          begin
4701             if Is_Static_Expression (N) then
4702                return True;
4703
4704             elsif Nkind (N) = N_Null then
4705                return True;
4706
4707             --  Attributes are allowed in general, even if their prefix is a
4708             --  formal type. (It seems that certain attributes known not to be
4709             --  static might not be allowed, but there are no rules to prevent
4710             --  them.)
4711
4712             elsif Nkind (N) = N_Attribute_Reference then
4713                return True;
4714
4715             --  The name of a discriminant evaluated within its parent type is
4716             --  defined to be preelaborable (10.2.1(8)). Note that we test for
4717             --  names that denote discriminals as well as discriminants to
4718             --  catch references occurring within init procs.
4719
4720             elsif Is_Entity_Name (N)
4721               and then
4722                 (Ekind (Entity (N)) = E_Discriminant
4723                   or else
4724                     ((Ekind (Entity (N)) = E_Constant
4725                        or else Ekind (Entity (N)) = E_In_Parameter)
4726                      and then Present (Discriminal_Link (Entity (N)))))
4727             then
4728                return True;
4729
4730             elsif Nkind (N) = N_Qualified_Expression then
4731                return Is_Preelaborable_Expression (Expression (N));
4732
4733             --  For aggregates we have to check that each of the associations
4734             --  is preelaborable.
4735
4736             elsif Nkind (N) = N_Aggregate
4737               or else Nkind (N) = N_Extension_Aggregate
4738             then
4739                Is_Array_Aggr := Is_Array_Type (Etype (N));
4740
4741                if Is_Array_Aggr then
4742                   Comp_Type := Component_Type (Etype (N));
4743                end if;
4744
4745                --  Check the ancestor part of extension aggregates, which must
4746                --  be either the name of a type that has preelaborable init or
4747                --  an expression that is preelaborable.
4748
4749                if Nkind (N) = N_Extension_Aggregate then
4750                   declare
4751                      Anc_Part : constant Node_Id := Ancestor_Part (N);
4752
4753                   begin
4754                      if Is_Entity_Name (Anc_Part)
4755                        and then Is_Type (Entity (Anc_Part))
4756                      then
4757                         if not Has_Preelaborable_Initialization
4758                                  (Entity (Anc_Part))
4759                         then
4760                            return False;
4761                         end if;
4762
4763                      elsif not Is_Preelaborable_Expression (Anc_Part) then
4764                         return False;
4765                      end if;
4766                   end;
4767                end if;
4768
4769                --  Check positional associations
4770
4771                Exp := First (Expressions (N));
4772                while Present (Exp) loop
4773                   if not Is_Preelaborable_Expression (Exp) then
4774                      return False;
4775                   end if;
4776
4777                   Next (Exp);
4778                end loop;
4779
4780                --  Check named associations
4781
4782                Assn := First (Component_Associations (N));
4783                while Present (Assn) loop
4784                   Choice := First (Choices (Assn));
4785                   while Present (Choice) loop
4786                      if Is_Array_Aggr then
4787                         if Nkind (Choice) = N_Others_Choice then
4788                            null;
4789
4790                         elsif Nkind (Choice) = N_Range then
4791                            if not Is_Static_Range (Choice) then
4792                               return False;
4793                            end if;
4794
4795                         elsif not Is_Static_Expression (Choice) then
4796                            return False;
4797                         end if;
4798
4799                      else
4800                         Comp_Type := Etype (Choice);
4801                      end if;
4802
4803                      Next (Choice);
4804                   end loop;
4805
4806                   --  If the association has a <> at this point, then we have
4807                   --  to check whether the component's type has preelaborable
4808                   --  initialization. Note that this only occurs when the
4809                   --  association's corresponding component does not have a
4810                   --  default expression, the latter case having already been
4811                   --  expanded as an expression for the association.
4812
4813                   if Box_Present (Assn) then
4814                      if not Has_Preelaborable_Initialization (Comp_Type) then
4815                         return False;
4816                      end if;
4817
4818                   --  In the expression case we check whether the expression
4819                   --  is preelaborable.
4820
4821                   elsif
4822                     not Is_Preelaborable_Expression (Expression (Assn))
4823                   then
4824                      return False;
4825                   end if;
4826
4827                   Next (Assn);
4828                end loop;
4829
4830                --  If we get here then aggregate as a whole is preelaborable
4831
4832                return True;
4833
4834             --  All other cases are not preelaborable
4835
4836             else
4837                return False;
4838             end if;
4839          end Is_Preelaborable_Expression;
4840
4841       --  Start of processing for Check_Components
4842
4843       begin
4844          --  Loop through entities of record or protected type
4845
4846          Ent := E;
4847          while Present (Ent) loop
4848
4849             --  We are interested only in components and discriminants
4850
4851             if Ekind (Ent) = E_Component
4852                 or else
4853                Ekind (Ent) = E_Discriminant
4854             then
4855                --  Get default expression if any. If there is no declaration
4856                --  node, it means we have an internal entity. The parent and
4857                --  tag fields are examples of such entities. For these cases,
4858                --  we just test the type of the entity.
4859
4860                if Present (Declaration_Node (Ent)) then
4861                   Exp := Expression (Declaration_Node (Ent));
4862                else
4863                   Exp := Empty;
4864                end if;
4865
4866                --  A component has PI if it has no default expression and the
4867                --  component type has PI.
4868
4869                if No (Exp) then
4870                   if not Has_Preelaborable_Initialization (Etype (Ent)) then
4871                      Has_PE := False;
4872                      exit;
4873                   end if;
4874
4875                --  Require the default expression to be preelaborable
4876
4877                elsif not Is_Preelaborable_Expression (Exp) then
4878                   Has_PE := False;
4879                   exit;
4880                end if;
4881             end if;
4882
4883             Next_Entity (Ent);
4884          end loop;
4885       end Check_Components;
4886
4887    --  Start of processing for Has_Preelaborable_Initialization
4888
4889    begin
4890       --  Immediate return if already marked as known preelaborable init. This
4891       --  covers types for which this function has already been called once
4892       --  and returned True (in which case the result is cached), and also
4893       --  types to which a pragma Preelaborable_Initialization applies.
4894
4895       if Known_To_Have_Preelab_Init (E) then
4896          return True;
4897       end if;
4898
4899       --  If the type is a subtype representing a generic actual type, then
4900       --  test whether its base type has preelaborable initialization since
4901       --  the subtype representing the actual does not inherit this attribute
4902       --  from the actual or formal. (but maybe it should???)
4903
4904       if Is_Generic_Actual_Type (E) then
4905          return Has_Preelaborable_Initialization (Base_Type (E));
4906       end if;
4907
4908       --  All elementary types have preelaborable initialization
4909
4910       if Is_Elementary_Type (E) then
4911          Has_PE := True;
4912
4913       --  Array types have PI if the component type has PI
4914
4915       elsif Is_Array_Type (E) then
4916          Has_PE := Has_Preelaborable_Initialization (Component_Type (E));
4917
4918       --  A derived type has preelaborable initialization if its parent type
4919       --  has preelaborable initialization and (in the case of a derived record
4920       --  extension) if the non-inherited components all have preelaborable
4921       --  initialization. However, a user-defined controlled type with an
4922       --  overriding Initialize procedure does not have preelaborable
4923       --  initialization.
4924
4925       elsif Is_Derived_Type (E) then
4926
4927          --  If the derived type is a private extension then it doesn't have
4928          --  preelaborable initialization.
4929
4930          if Ekind (Base_Type (E)) = E_Record_Type_With_Private then
4931             return False;
4932          end if;
4933
4934          --  First check whether ancestor type has preelaborable initialization
4935
4936          Has_PE := Has_Preelaborable_Initialization (Etype (Base_Type (E)));
4937
4938          --  If OK, check extension components (if any)
4939
4940          if Has_PE and then Is_Record_Type (E) then
4941             Check_Components (First_Entity (E));
4942          end if;
4943
4944          --  Check specifically for 10.2.1(11.4/2) exception: a controlled type
4945          --  with a user defined Initialize procedure does not have PI.
4946
4947          if Has_PE
4948            and then Is_Controlled (E)
4949            and then Has_Overriding_Initialize (E)
4950          then
4951             Has_PE := False;
4952          end if;
4953
4954       --  Private types not derived from a type having preelaborable init and
4955       --  that are not marked with pragma Preelaborable_Initialization do not
4956       --  have preelaborable initialization.
4957
4958       elsif Is_Private_Type (E) then
4959          return False;
4960
4961       --  Record type has PI if it is non private and all components have PI
4962
4963       elsif Is_Record_Type (E) then
4964          Has_PE := True;
4965          Check_Components (First_Entity (E));
4966
4967       --  Protected types must not have entries, and components must meet
4968       --  same set of rules as for record components.
4969
4970       elsif Is_Protected_Type (E) then
4971          if Has_Entries (E) then
4972             Has_PE := False;
4973          else
4974             Has_PE := True;
4975             Check_Components (First_Entity (E));
4976             Check_Components (First_Private_Entity (E));
4977          end if;
4978
4979       --  Type System.Address always has preelaborable initialization
4980
4981       elsif Is_RTE (E, RE_Address) then
4982          Has_PE := True;
4983
4984       --  In all other cases, type does not have preelaborable initialization
4985
4986       else
4987          return False;
4988       end if;
4989
4990       --  If type has preelaborable initialization, cache result
4991
4992       if Has_PE then
4993          Set_Known_To_Have_Preelab_Init (E);
4994       end if;
4995
4996       return Has_PE;
4997    end Has_Preelaborable_Initialization;
4998
4999    ---------------------------
5000    -- Has_Private_Component --
5001    ---------------------------
5002
5003    function Has_Private_Component (Type_Id : Entity_Id) return Boolean is
5004       Btype     : Entity_Id := Base_Type (Type_Id);
5005       Component : Entity_Id;
5006
5007    begin
5008       if Error_Posted (Type_Id)
5009         or else Error_Posted (Btype)
5010       then
5011          return False;
5012       end if;
5013
5014       if Is_Class_Wide_Type (Btype) then
5015          Btype := Root_Type (Btype);
5016       end if;
5017
5018       if Is_Private_Type (Btype) then
5019          declare
5020             UT : constant Entity_Id := Underlying_Type (Btype);
5021          begin
5022             if No (UT) then
5023                if No (Full_View (Btype)) then
5024                   return not Is_Generic_Type (Btype)
5025                     and then not Is_Generic_Type (Root_Type (Btype));
5026                else
5027                   return not Is_Generic_Type (Root_Type (Full_View (Btype)));
5028                end if;
5029             else
5030                return not Is_Frozen (UT) and then Has_Private_Component (UT);
5031             end if;
5032          end;
5033
5034       elsif Is_Array_Type (Btype) then
5035          return Has_Private_Component (Component_Type (Btype));
5036
5037       elsif Is_Record_Type (Btype) then
5038          Component := First_Component (Btype);
5039          while Present (Component) loop
5040             if Has_Private_Component (Etype (Component)) then
5041                return True;
5042             end if;
5043
5044             Next_Component (Component);
5045          end loop;
5046
5047          return False;
5048
5049       elsif Is_Protected_Type (Btype)
5050         and then Present (Corresponding_Record_Type (Btype))
5051       then
5052          return Has_Private_Component (Corresponding_Record_Type (Btype));
5053
5054       else
5055          return False;
5056       end if;
5057    end Has_Private_Component;
5058
5059    ----------------
5060    -- Has_Stream --
5061    ----------------
5062
5063    function Has_Stream (T : Entity_Id) return Boolean is
5064       E : Entity_Id;
5065
5066    begin
5067       if No (T) then
5068          return False;
5069
5070       elsif Is_RTE (Root_Type (T), RE_Root_Stream_Type) then
5071          return True;
5072
5073       elsif Is_Array_Type (T) then
5074          return Has_Stream (Component_Type (T));
5075
5076       elsif Is_Record_Type (T) then
5077          E := First_Component (T);
5078          while Present (E) loop
5079             if Has_Stream (Etype (E)) then
5080                return True;
5081             else
5082                Next_Component (E);
5083             end if;
5084          end loop;
5085
5086          return False;
5087
5088       elsif Is_Private_Type (T) then
5089          return Has_Stream (Underlying_Type (T));
5090
5091       else
5092          return False;
5093       end if;
5094    end Has_Stream;
5095
5096    --------------------------
5097    -- Has_Tagged_Component --
5098    --------------------------
5099
5100    function Has_Tagged_Component (Typ : Entity_Id) return Boolean is
5101       Comp : Entity_Id;
5102
5103    begin
5104       if Is_Private_Type (Typ)
5105         and then Present (Underlying_Type (Typ))
5106       then
5107          return Has_Tagged_Component (Underlying_Type (Typ));
5108
5109       elsif Is_Array_Type (Typ) then
5110          return Has_Tagged_Component (Component_Type (Typ));
5111
5112       elsif Is_Tagged_Type (Typ) then
5113          return True;
5114
5115       elsif Is_Record_Type (Typ) then
5116          Comp := First_Component (Typ);
5117          while Present (Comp) loop
5118             if Has_Tagged_Component (Etype (Comp)) then
5119                return True;
5120             end if;
5121
5122             Next_Component (Comp);
5123          end loop;
5124
5125          return False;
5126
5127       else
5128          return False;
5129       end if;
5130    end Has_Tagged_Component;
5131
5132    --------------------------
5133    -- Implements_Interface --
5134    --------------------------
5135
5136    function Implements_Interface
5137      (Typ_Ent         : Entity_Id;
5138       Iface_Ent       : Entity_Id;
5139       Exclude_Parents : Boolean := False) return Boolean
5140    is
5141       Ifaces_List : Elist_Id;
5142       Elmt        : Elmt_Id;
5143       Iface       : Entity_Id := Base_Type (Iface_Ent);
5144       Typ         : Entity_Id := Base_Type (Typ_Ent);
5145
5146    begin
5147       if Is_Class_Wide_Type (Typ) then
5148          Typ := Root_Type (Typ);
5149       end if;
5150
5151       if not Has_Interfaces (Typ) then
5152          return False;
5153       end if;
5154
5155       if Is_Class_Wide_Type (Iface) then
5156          Iface := Root_Type (Iface);
5157       end if;
5158
5159       Collect_Interfaces (Typ, Ifaces_List);
5160
5161       Elmt := First_Elmt (Ifaces_List);
5162       while Present (Elmt) loop
5163          if Is_Ancestor (Node (Elmt), Typ)
5164            and then Exclude_Parents
5165          then
5166             null;
5167
5168          elsif Node (Elmt) = Iface then
5169             return True;
5170          end if;
5171
5172          Next_Elmt (Elmt);
5173       end loop;
5174
5175       return False;
5176    end Implements_Interface;
5177
5178    -----------------
5179    -- In_Instance --
5180    -----------------
5181
5182    function In_Instance return Boolean is
5183       Curr_Unit : constant Entity_Id := Cunit_Entity (Current_Sem_Unit);
5184       S         : Entity_Id;
5185
5186    begin
5187       S := Current_Scope;
5188       while Present (S)
5189         and then S /= Standard_Standard
5190       loop
5191          if (Ekind (S) = E_Function
5192               or else Ekind (S) = E_Package
5193               or else Ekind (S) = E_Procedure)
5194            and then Is_Generic_Instance (S)
5195          then
5196             --  A child instance is always compiled in the context of a parent
5197             --  instance. Nevertheless, the actuals are not analyzed in an
5198             --  instance context. We detect this case by examining the current
5199             --  compilation unit, which must be a child instance, and checking
5200             --  that it is not currently on the scope stack.
5201
5202             if Is_Child_Unit (Curr_Unit)
5203               and then
5204                 Nkind (Unit (Cunit (Current_Sem_Unit)))
5205                   = N_Package_Instantiation
5206               and then not In_Open_Scopes (Curr_Unit)
5207             then
5208                return False;
5209             else
5210                return True;
5211             end if;
5212          end if;
5213
5214          S := Scope (S);
5215       end loop;
5216
5217       return False;
5218    end In_Instance;
5219
5220    ----------------------
5221    -- In_Instance_Body --
5222    ----------------------
5223
5224    function In_Instance_Body return Boolean is
5225       S : Entity_Id;
5226
5227    begin
5228       S := Current_Scope;
5229       while Present (S)
5230         and then S /= Standard_Standard
5231       loop
5232          if (Ekind (S) = E_Function
5233               or else Ekind (S) = E_Procedure)
5234            and then Is_Generic_Instance (S)
5235          then
5236             return True;
5237
5238          elsif Ekind (S) = E_Package
5239            and then In_Package_Body (S)
5240            and then Is_Generic_Instance (S)
5241          then
5242             return True;
5243          end if;
5244
5245          S := Scope (S);
5246       end loop;
5247
5248       return False;
5249    end In_Instance_Body;
5250
5251    -----------------------------
5252    -- In_Instance_Not_Visible --
5253    -----------------------------
5254
5255    function In_Instance_Not_Visible return Boolean is
5256       S : Entity_Id;
5257
5258    begin
5259       S := Current_Scope;
5260       while Present (S)
5261         and then S /= Standard_Standard
5262       loop
5263          if (Ekind (S) = E_Function
5264               or else Ekind (S) = E_Procedure)
5265            and then Is_Generic_Instance (S)
5266          then
5267             return True;
5268
5269          elsif Ekind (S) = E_Package
5270            and then (In_Package_Body (S) or else In_Private_Part (S))
5271            and then Is_Generic_Instance (S)
5272          then
5273             return True;
5274          end if;
5275
5276          S := Scope (S);
5277       end loop;
5278
5279       return False;
5280    end In_Instance_Not_Visible;
5281
5282    ------------------------------
5283    -- In_Instance_Visible_Part --
5284    ------------------------------
5285
5286    function In_Instance_Visible_Part return Boolean is
5287       S : Entity_Id;
5288
5289    begin
5290       S := Current_Scope;
5291       while Present (S)
5292         and then S /= Standard_Standard
5293       loop
5294          if Ekind (S) = E_Package
5295            and then Is_Generic_Instance (S)
5296            and then not In_Package_Body (S)
5297            and then not In_Private_Part (S)
5298          then
5299             return True;
5300          end if;
5301
5302          S := Scope (S);
5303       end loop;
5304
5305       return False;
5306    end In_Instance_Visible_Part;
5307
5308    ---------------------
5309    -- In_Package_Body --
5310    ---------------------
5311
5312    function In_Package_Body return Boolean is
5313       S : Entity_Id;
5314
5315    begin
5316       S := Current_Scope;
5317       while Present (S)
5318         and then S /= Standard_Standard
5319       loop
5320          if Ekind (S) = E_Package
5321            and then In_Package_Body (S)
5322          then
5323             return True;
5324          else
5325             S := Scope (S);
5326          end if;
5327       end loop;
5328
5329       return False;
5330    end In_Package_Body;
5331
5332    --------------------------------
5333    -- In_Parameter_Specification --
5334    --------------------------------
5335
5336    function In_Parameter_Specification (N : Node_Id) return Boolean is
5337       PN : Node_Id;
5338
5339    begin
5340       PN := Parent (N);
5341       while Present (PN) loop
5342          if Nkind (PN) = N_Parameter_Specification then
5343             return True;
5344          end if;
5345
5346          PN := Parent (PN);
5347       end loop;
5348
5349       return False;
5350    end In_Parameter_Specification;
5351
5352    --------------------------------------
5353    -- In_Subprogram_Or_Concurrent_Unit --
5354    --------------------------------------
5355
5356    function In_Subprogram_Or_Concurrent_Unit return Boolean is
5357       E : Entity_Id;
5358       K : Entity_Kind;
5359
5360    begin
5361       --  Use scope chain to check successively outer scopes
5362
5363       E := Current_Scope;
5364       loop
5365          K := Ekind (E);
5366
5367          if K in Subprogram_Kind
5368            or else K in Concurrent_Kind
5369            or else K in Generic_Subprogram_Kind
5370          then
5371             return True;
5372
5373          elsif E = Standard_Standard then
5374             return False;
5375          end if;
5376
5377          E := Scope (E);
5378       end loop;
5379    end In_Subprogram_Or_Concurrent_Unit;
5380
5381    ---------------------
5382    -- In_Visible_Part --
5383    ---------------------
5384
5385    function In_Visible_Part (Scope_Id : Entity_Id) return Boolean is
5386    begin
5387       return
5388         Is_Package_Or_Generic_Package (Scope_Id)
5389           and then In_Open_Scopes (Scope_Id)
5390           and then not In_Package_Body (Scope_Id)
5391           and then not In_Private_Part (Scope_Id);
5392    end In_Visible_Part;
5393
5394    ---------------------------------
5395    -- Insert_Explicit_Dereference --
5396    ---------------------------------
5397
5398    procedure Insert_Explicit_Dereference (N : Node_Id) is
5399       New_Prefix : constant Node_Id := Relocate_Node (N);
5400       Ent        : Entity_Id := Empty;
5401       Pref       : Node_Id;
5402       I          : Interp_Index;
5403       It         : Interp;
5404       T          : Entity_Id;
5405
5406    begin
5407       Save_Interps (N, New_Prefix);
5408
5409       --  Check if the node relocation requires readjustment of some SCIL
5410       --  dispatching node.
5411
5412       if Generate_SCIL
5413         and then Nkind (N) = N_Function_Call
5414       then
5415          Adjust_SCIL_Node (N, New_Prefix);
5416       end if;
5417
5418       Rewrite (N, Make_Explicit_Dereference (Sloc (N), Prefix => New_Prefix));
5419
5420       Set_Etype (N, Designated_Type (Etype (New_Prefix)));
5421
5422       if Is_Overloaded (New_Prefix) then
5423
5424          --  The dereference is also overloaded, and its interpretations are
5425          --  the designated types of the interpretations of the original node.
5426
5427          Set_Etype (N, Any_Type);
5428
5429          Get_First_Interp (New_Prefix, I, It);
5430          while Present (It.Nam) loop
5431             T := It.Typ;
5432
5433             if Is_Access_Type (T) then
5434                Add_One_Interp (N, Designated_Type (T), Designated_Type (T));
5435             end if;
5436
5437             Get_Next_Interp (I, It);
5438          end loop;
5439
5440          End_Interp_List;
5441
5442       else
5443          --  Prefix is unambiguous: mark the original prefix (which might
5444          --  Come_From_Source) as a reference, since the new (relocated) one
5445          --  won't be taken into account.
5446
5447          if Is_Entity_Name (New_Prefix) then
5448             Ent := Entity (New_Prefix);
5449
5450          --  For a retrieval of a subcomponent of some composite object,
5451          --  retrieve the ultimate entity if there is one.
5452
5453          elsif Nkind (New_Prefix) = N_Selected_Component
5454            or else Nkind (New_Prefix) = N_Indexed_Component
5455          then
5456             Pref := Prefix (New_Prefix);
5457             while Present (Pref)
5458               and then
5459                 (Nkind (Pref) = N_Selected_Component
5460                   or else Nkind (Pref) = N_Indexed_Component)
5461             loop
5462                Pref := Prefix (Pref);
5463             end loop;
5464
5465             if Present (Pref) and then Is_Entity_Name (Pref) then
5466                Ent := Entity (Pref);
5467             end if;
5468          end if;
5469
5470          if Present (Ent) then
5471             Generate_Reference (Ent, New_Prefix);
5472          end if;
5473       end if;
5474    end Insert_Explicit_Dereference;
5475
5476    ------------------------------------------
5477    -- Inspect_Deferred_Constant_Completion --
5478    ------------------------------------------
5479
5480    procedure Inspect_Deferred_Constant_Completion (Decls : List_Id) is
5481       Decl   : Node_Id;
5482
5483    begin
5484       Decl := First (Decls);
5485       while Present (Decl) loop
5486
5487          --  Deferred constant signature
5488
5489          if Nkind (Decl) = N_Object_Declaration
5490            and then Constant_Present (Decl)
5491            and then No (Expression (Decl))
5492
5493             --  No need to check internally generated constants
5494
5495            and then Comes_From_Source (Decl)
5496
5497             --  The constant is not completed. A full object declaration
5498             --  or a pragma Import complete a deferred constant.
5499
5500            and then not Has_Completion (Defining_Identifier (Decl))
5501          then
5502             Error_Msg_N
5503               ("constant declaration requires initialization expression",
5504               Defining_Identifier (Decl));
5505          end if;
5506
5507          Decl := Next (Decl);
5508       end loop;
5509    end Inspect_Deferred_Constant_Completion;
5510
5511    -------------------
5512    -- Is_AAMP_Float --
5513    -------------------
5514
5515    function Is_AAMP_Float (E : Entity_Id) return Boolean is
5516       pragma Assert (Is_Type (E));
5517    begin
5518       return AAMP_On_Target
5519          and then Is_Floating_Point_Type (E)
5520          and then E = Base_Type (E);
5521    end Is_AAMP_Float;
5522
5523    -----------------------------
5524    -- Is_Actual_Out_Parameter --
5525    -----------------------------
5526
5527    function Is_Actual_Out_Parameter (N : Node_Id) return Boolean is
5528       Formal : Entity_Id;
5529       Call   : Node_Id;
5530    begin
5531       Find_Actual (N, Formal, Call);
5532       return Present (Formal)
5533         and then Ekind (Formal) = E_Out_Parameter;
5534    end Is_Actual_Out_Parameter;
5535
5536    -------------------------
5537    -- Is_Actual_Parameter --
5538    -------------------------
5539
5540    function Is_Actual_Parameter (N : Node_Id) return Boolean is
5541       PK : constant Node_Kind := Nkind (Parent (N));
5542
5543    begin
5544       case PK is
5545          when N_Parameter_Association =>
5546             return N = Explicit_Actual_Parameter (Parent (N));
5547
5548          when N_Function_Call | N_Procedure_Call_Statement =>
5549             return Is_List_Member (N)
5550               and then
5551                 List_Containing (N) = Parameter_Associations (Parent (N));
5552
5553          when others =>
5554             return False;
5555       end case;
5556    end Is_Actual_Parameter;
5557
5558    ---------------------
5559    -- Is_Aliased_View --
5560    ---------------------
5561
5562    function Is_Aliased_View (Obj : Node_Id) return Boolean is
5563       E : Entity_Id;
5564
5565    begin
5566       if Is_Entity_Name (Obj) then
5567
5568          E := Entity (Obj);
5569
5570          return
5571            (Is_Object (E)
5572              and then
5573                (Is_Aliased (E)
5574                   or else (Present (Renamed_Object (E))
5575                              and then Is_Aliased_View (Renamed_Object (E)))))
5576
5577            or else ((Is_Formal (E)
5578                       or else Ekind (E) = E_Generic_In_Out_Parameter
5579                       or else Ekind (E) = E_Generic_In_Parameter)
5580                     and then Is_Tagged_Type (Etype (E)))
5581
5582            or else (Is_Concurrent_Type (E)
5583                      and then In_Open_Scopes (E))
5584
5585             --  Current instance of type, either directly or as rewritten
5586             --  reference to the current object.
5587
5588            or else (Is_Entity_Name (Original_Node (Obj))
5589                      and then Present (Entity (Original_Node (Obj)))
5590                      and then Is_Type (Entity (Original_Node (Obj))))
5591
5592            or else (Is_Type (E) and then E = Current_Scope)
5593
5594            or else (Is_Incomplete_Or_Private_Type (E)
5595                      and then Full_View (E) = Current_Scope);
5596
5597       elsif Nkind (Obj) = N_Selected_Component then
5598          return Is_Aliased (Entity (Selector_Name (Obj)));
5599
5600       elsif Nkind (Obj) = N_Indexed_Component then
5601          return Has_Aliased_Components (Etype (Prefix (Obj)))
5602            or else
5603              (Is_Access_Type (Etype (Prefix (Obj)))
5604                and then
5605               Has_Aliased_Components
5606                 (Designated_Type (Etype (Prefix (Obj)))));
5607
5608       elsif Nkind (Obj) = N_Unchecked_Type_Conversion
5609         or else Nkind (Obj) = N_Type_Conversion
5610       then
5611          return Is_Tagged_Type (Etype (Obj))
5612            and then Is_Aliased_View (Expression (Obj));
5613
5614       elsif Nkind (Obj) = N_Explicit_Dereference then
5615          return Nkind (Original_Node (Obj)) /= N_Function_Call;
5616
5617       else
5618          return False;
5619       end if;
5620    end Is_Aliased_View;
5621
5622    -------------------------
5623    -- Is_Ancestor_Package --
5624    -------------------------
5625
5626    function Is_Ancestor_Package
5627      (E1 : Entity_Id;
5628       E2 : Entity_Id) return Boolean
5629    is
5630       Par : Entity_Id;
5631
5632    begin
5633       Par := E2;
5634       while Present (Par)
5635         and then Par /= Standard_Standard
5636       loop
5637          if Par = E1 then
5638             return True;
5639          end if;
5640
5641          Par := Scope (Par);
5642       end loop;
5643
5644       return False;
5645    end Is_Ancestor_Package;
5646
5647    ----------------------
5648    -- Is_Atomic_Object --
5649    ----------------------
5650
5651    function Is_Atomic_Object (N : Node_Id) return Boolean is
5652
5653       function Object_Has_Atomic_Components (N : Node_Id) return Boolean;
5654       --  Determines if given object has atomic components
5655
5656       function Is_Atomic_Prefix (N : Node_Id) return Boolean;
5657       --  If prefix is an implicit dereference, examine designated type
5658
5659       ----------------------
5660       -- Is_Atomic_Prefix --
5661       ----------------------
5662
5663       function Is_Atomic_Prefix (N : Node_Id) return Boolean is
5664       begin
5665          if Is_Access_Type (Etype (N)) then
5666             return
5667               Has_Atomic_Components (Designated_Type (Etype (N)));
5668          else
5669             return Object_Has_Atomic_Components (N);
5670          end if;
5671       end Is_Atomic_Prefix;
5672
5673       ----------------------------------
5674       -- Object_Has_Atomic_Components --
5675       ----------------------------------
5676
5677       function Object_Has_Atomic_Components (N : Node_Id) return Boolean is
5678       begin
5679          if Has_Atomic_Components (Etype (N))
5680            or else Is_Atomic (Etype (N))
5681          then
5682             return True;
5683
5684          elsif Is_Entity_Name (N)
5685            and then (Has_Atomic_Components (Entity (N))
5686                       or else Is_Atomic (Entity (N)))
5687          then
5688             return True;
5689
5690          elsif Nkind (N) = N_Indexed_Component
5691            or else Nkind (N) = N_Selected_Component
5692          then
5693             return Is_Atomic_Prefix (Prefix (N));
5694
5695          else
5696             return False;
5697          end if;
5698       end Object_Has_Atomic_Components;
5699
5700    --  Start of processing for Is_Atomic_Object
5701
5702    begin
5703       if Is_Atomic (Etype (N))
5704         or else (Is_Entity_Name (N) and then Is_Atomic (Entity (N)))
5705       then
5706          return True;
5707
5708       elsif Nkind (N) = N_Indexed_Component
5709         or else Nkind (N) = N_Selected_Component
5710       then
5711          return Is_Atomic_Prefix (Prefix (N));
5712
5713       else
5714          return False;
5715       end if;
5716    end Is_Atomic_Object;
5717
5718    -------------------------
5719    -- Is_Coextension_Root --
5720    -------------------------
5721
5722    function Is_Coextension_Root (N : Node_Id) return Boolean is
5723    begin
5724       return
5725         Nkind (N) = N_Allocator
5726           and then Present (Coextensions (N))
5727
5728          --  Anonymous access discriminants carry a list of all nested
5729          --  controlled coextensions.
5730
5731           and then not Is_Dynamic_Coextension (N)
5732           and then not Is_Static_Coextension (N);
5733    end Is_Coextension_Root;
5734
5735    -----------------------------
5736    -- Is_Concurrent_Interface --
5737    -----------------------------
5738
5739    function Is_Concurrent_Interface (T : Entity_Id) return Boolean is
5740    begin
5741       return
5742         Is_Interface (T)
5743           and then
5744             (Is_Protected_Interface (T)
5745                or else Is_Synchronized_Interface (T)
5746                or else Is_Task_Interface (T));
5747    end Is_Concurrent_Interface;
5748
5749    --------------------------------------
5750    -- Is_Controlling_Limited_Procedure --
5751    --------------------------------------
5752
5753    function Is_Controlling_Limited_Procedure
5754      (Proc_Nam : Entity_Id) return Boolean
5755    is
5756       Param_Typ : Entity_Id := Empty;
5757
5758    begin
5759       if Ekind (Proc_Nam) = E_Procedure
5760         and then Present (Parameter_Specifications (Parent (Proc_Nam)))
5761       then
5762          Param_Typ := Etype (Parameter_Type (First (
5763                         Parameter_Specifications (Parent (Proc_Nam)))));
5764
5765       --  In this case where an Itype was created, the procedure call has been
5766       --  rewritten.
5767
5768       elsif Present (Associated_Node_For_Itype (Proc_Nam))
5769         and then Present (Original_Node (Associated_Node_For_Itype (Proc_Nam)))
5770         and then
5771           Present (Parameter_Associations
5772                      (Associated_Node_For_Itype (Proc_Nam)))
5773       then
5774          Param_Typ :=
5775            Etype (First (Parameter_Associations
5776                           (Associated_Node_For_Itype (Proc_Nam))));
5777       end if;
5778
5779       if Present (Param_Typ) then
5780          return
5781            Is_Interface (Param_Typ)
5782              and then Is_Limited_Record (Param_Typ);
5783       end if;
5784
5785       return False;
5786    end Is_Controlling_Limited_Procedure;
5787
5788    -----------------------------
5789    -- Is_CPP_Constructor_Call --
5790    -----------------------------
5791
5792    function Is_CPP_Constructor_Call (N : Node_Id) return Boolean is
5793    begin
5794       return Nkind (N) = N_Function_Call
5795         and then Is_CPP_Class (Etype (Etype (N)))
5796         and then Is_Constructor (Entity (Name (N)))
5797         and then Is_Imported (Entity (Name (N)));
5798    end Is_CPP_Constructor_Call;
5799
5800    ----------------------------------------------
5801    -- Is_Dependent_Component_Of_Mutable_Object --
5802    ----------------------------------------------
5803
5804    function Is_Dependent_Component_Of_Mutable_Object
5805      (Object : Node_Id) return   Boolean
5806    is
5807       P           : Node_Id;
5808       Prefix_Type : Entity_Id;
5809       P_Aliased   : Boolean := False;
5810       Comp        : Entity_Id;
5811
5812       function Is_Declared_Within_Variant (Comp : Entity_Id) return Boolean;
5813       --  Returns True if and only if Comp is declared within a variant part
5814
5815       --------------------------------
5816       -- Is_Declared_Within_Variant --
5817       --------------------------------
5818
5819       function Is_Declared_Within_Variant (Comp : Entity_Id) return Boolean is
5820          Comp_Decl : constant Node_Id   := Parent (Comp);
5821          Comp_List : constant Node_Id   := Parent (Comp_Decl);
5822       begin
5823          return Nkind (Parent (Comp_List)) = N_Variant;
5824       end Is_Declared_Within_Variant;
5825
5826    --  Start of processing for Is_Dependent_Component_Of_Mutable_Object
5827
5828    begin
5829       if Is_Variable (Object) then
5830
5831          if Nkind (Object) = N_Selected_Component then
5832             P := Prefix (Object);
5833             Prefix_Type := Etype (P);
5834
5835             if Is_Entity_Name (P) then
5836
5837                if Ekind (Entity (P)) = E_Generic_In_Out_Parameter then
5838                   Prefix_Type := Base_Type (Prefix_Type);
5839                end if;
5840
5841                if Is_Aliased (Entity (P)) then
5842                   P_Aliased := True;
5843                end if;
5844
5845             --  A discriminant check on a selected component may be
5846             --  expanded into a dereference when removing side-effects.
5847             --  Recover the original node and its type, which may be
5848             --  unconstrained.
5849
5850             elsif Nkind (P) = N_Explicit_Dereference
5851               and then not (Comes_From_Source (P))
5852             then
5853                P := Original_Node (P);
5854                Prefix_Type := Etype (P);
5855
5856             else
5857                --  Check for prefix being an aliased component ???
5858                null;
5859
5860             end if;
5861
5862             --  A heap object is constrained by its initial value
5863
5864             --  Ada 2005 (AI-363): Always assume the object could be mutable in
5865             --  the dereferenced case, since the access value might denote an
5866             --  unconstrained aliased object, whereas in Ada 95 the designated
5867             --  object is guaranteed to be constrained. A worst-case assumption
5868             --  has to apply in Ada 2005 because we can't tell at compile time
5869             --  whether the object is "constrained by its initial value"
5870             --  (despite the fact that 3.10.2(26/2) and 8.5.1(5/2) are
5871             --  semantic rules -- these rules are acknowledged to need fixing).
5872
5873             if Ada_Version < Ada_05 then
5874                if Is_Access_Type (Prefix_Type)
5875                  or else Nkind (P) = N_Explicit_Dereference
5876                then
5877                   return False;
5878                end if;
5879
5880             elsif Ada_Version >= Ada_05 then
5881                if Is_Access_Type (Prefix_Type) then
5882
5883                   --  If the access type is pool-specific, and there is no
5884                   --  constrained partial view of the designated type, then the
5885                   --  designated object is known to be constrained.
5886
5887                   if Ekind (Prefix_Type) = E_Access_Type
5888                     and then not Has_Constrained_Partial_View
5889                                    (Designated_Type (Prefix_Type))
5890                   then
5891                      return False;
5892
5893                   --  Otherwise (general access type, or there is a constrained
5894                   --  partial view of the designated type), we need to check
5895                   --  based on the designated type.
5896
5897                   else
5898                      Prefix_Type := Designated_Type (Prefix_Type);
5899                   end if;
5900                end if;
5901             end if;
5902
5903             Comp :=
5904               Original_Record_Component (Entity (Selector_Name (Object)));
5905
5906             --  As per AI-0017, the renaming is illegal in a generic body,
5907             --  even if the subtype is indefinite.
5908
5909             --  Ada 2005 (AI-363): In Ada 2005 an aliased object can be mutable
5910
5911             if not Is_Constrained (Prefix_Type)
5912               and then (not Is_Indefinite_Subtype (Prefix_Type)
5913                          or else
5914                           (Is_Generic_Type (Prefix_Type)
5915                             and then Ekind (Current_Scope) = E_Generic_Package
5916                             and then In_Package_Body (Current_Scope)))
5917
5918               and then (Is_Declared_Within_Variant (Comp)
5919                           or else Has_Discriminant_Dependent_Constraint (Comp))
5920               and then (not P_Aliased or else Ada_Version >= Ada_05)
5921             then
5922                return True;
5923
5924             else
5925                return
5926                  Is_Dependent_Component_Of_Mutable_Object (Prefix (Object));
5927
5928             end if;
5929
5930          elsif Nkind (Object) = N_Indexed_Component
5931            or else Nkind (Object) = N_Slice
5932          then
5933             return Is_Dependent_Component_Of_Mutable_Object (Prefix (Object));
5934
5935          --  A type conversion that Is_Variable is a view conversion:
5936          --  go back to the denoted object.
5937
5938          elsif Nkind (Object) = N_Type_Conversion then
5939             return
5940               Is_Dependent_Component_Of_Mutable_Object (Expression (Object));
5941          end if;
5942       end if;
5943
5944       return False;
5945    end Is_Dependent_Component_Of_Mutable_Object;
5946
5947    ---------------------
5948    -- Is_Dereferenced --
5949    ---------------------
5950
5951    function Is_Dereferenced (N : Node_Id) return Boolean is
5952       P : constant Node_Id := Parent (N);
5953    begin
5954       return
5955          (Nkind (P) = N_Selected_Component
5956             or else
5957           Nkind (P) = N_Explicit_Dereference
5958             or else
5959           Nkind (P) = N_Indexed_Component
5960             or else
5961           Nkind (P) = N_Slice)
5962         and then Prefix (P) = N;
5963    end Is_Dereferenced;
5964
5965    ----------------------
5966    -- Is_Descendent_Of --
5967    ----------------------
5968
5969    function Is_Descendent_Of (T1 : Entity_Id; T2 : Entity_Id) return Boolean is
5970       T    : Entity_Id;
5971       Etyp : Entity_Id;
5972
5973    begin
5974       pragma Assert (Nkind (T1) in N_Entity);
5975       pragma Assert (Nkind (T2) in N_Entity);
5976
5977       T := Base_Type (T1);
5978
5979       --  Immediate return if the types match
5980
5981       if T = T2 then
5982          return True;
5983
5984       --  Comment needed here ???
5985
5986       elsif Ekind (T) = E_Class_Wide_Type then
5987          return Etype (T) = T2;
5988
5989       --  All other cases
5990
5991       else
5992          loop
5993             Etyp := Etype (T);
5994
5995             --  Done if we found the type we are looking for
5996
5997             if Etyp = T2 then
5998                return True;
5999
6000             --  Done if no more derivations to check
6001
6002             elsif T = T1
6003               or else T = Etyp
6004             then
6005                return False;
6006
6007             --  Following test catches error cases resulting from prev errors
6008
6009             elsif No (Etyp) then
6010                return False;
6011
6012             elsif Is_Private_Type (T) and then Etyp = Full_View (T) then
6013                return False;
6014
6015             elsif Is_Private_Type (Etyp) and then Full_View (Etyp) = T then
6016                return False;
6017             end if;
6018
6019             T := Base_Type (Etyp);
6020          end loop;
6021       end if;
6022    end Is_Descendent_Of;
6023
6024    --------------
6025    -- Is_False --
6026    --------------
6027
6028    function Is_False (U : Uint) return Boolean is
6029    begin
6030       return (U = 0);
6031    end Is_False;
6032
6033    ---------------------------
6034    -- Is_Fixed_Model_Number --
6035    ---------------------------
6036
6037    function Is_Fixed_Model_Number (U : Ureal; T : Entity_Id) return Boolean is
6038       S : constant Ureal := Small_Value (T);
6039       M : Urealp.Save_Mark;
6040       R : Boolean;
6041    begin
6042       M := Urealp.Mark;
6043       R := (U = UR_Trunc (U / S) * S);
6044       Urealp.Release (M);
6045       return R;
6046    end Is_Fixed_Model_Number;
6047
6048    -------------------------------
6049    -- Is_Fully_Initialized_Type --
6050    -------------------------------
6051
6052    function Is_Fully_Initialized_Type (Typ : Entity_Id) return Boolean is
6053    begin
6054       if Is_Scalar_Type (Typ) then
6055          return False;
6056
6057       elsif Is_Access_Type (Typ) then
6058          return True;
6059
6060       elsif Is_Array_Type (Typ) then
6061          if Is_Fully_Initialized_Type (Component_Type (Typ)) then
6062             return True;
6063          end if;
6064
6065          --  An interesting case, if we have a constrained type one of whose
6066          --  bounds is known to be null, then there are no elements to be
6067          --  initialized, so all the elements are initialized!
6068
6069          if Is_Constrained (Typ) then
6070             declare
6071                Indx     : Node_Id;
6072                Indx_Typ : Entity_Id;
6073                Lbd, Hbd : Node_Id;
6074
6075             begin
6076                Indx := First_Index (Typ);
6077                while Present (Indx) loop
6078                   if Etype (Indx) = Any_Type then
6079                      return False;
6080
6081                   --  If index is a range, use directly
6082
6083                   elsif Nkind (Indx) = N_Range then
6084                      Lbd := Low_Bound  (Indx);
6085                      Hbd := High_Bound (Indx);
6086
6087                   else
6088                      Indx_Typ := Etype (Indx);
6089
6090                      if Is_Private_Type (Indx_Typ)  then
6091                         Indx_Typ := Full_View (Indx_Typ);
6092                      end if;
6093
6094                      if No (Indx_Typ) or else Etype (Indx_Typ) = Any_Type then
6095                         return False;
6096                      else
6097                         Lbd := Type_Low_Bound  (Indx_Typ);
6098                         Hbd := Type_High_Bound (Indx_Typ);
6099                      end if;
6100                   end if;
6101
6102                   if Compile_Time_Known_Value (Lbd)
6103                     and then Compile_Time_Known_Value (Hbd)
6104                   then
6105                      if Expr_Value (Hbd) < Expr_Value (Lbd) then
6106                         return True;
6107                      end if;
6108                   end if;
6109
6110                   Next_Index (Indx);
6111                end loop;
6112             end;
6113          end if;
6114
6115          --  If no null indexes, then type is not fully initialized
6116
6117          return False;
6118
6119       --  Record types
6120
6121       elsif Is_Record_Type (Typ) then
6122          if Has_Discriminants (Typ)
6123            and then
6124              Present (Discriminant_Default_Value (First_Discriminant (Typ)))
6125            and then Is_Fully_Initialized_Variant (Typ)
6126          then
6127             return True;
6128          end if;
6129
6130          --  Controlled records are considered to be fully initialized if
6131          --  there is a user defined Initialize routine. This may not be
6132          --  entirely correct, but as the spec notes, we are guessing here
6133          --  what is best from the point of view of issuing warnings.
6134
6135          if Is_Controlled (Typ) then
6136             declare
6137                Utyp : constant Entity_Id := Underlying_Type (Typ);
6138
6139             begin
6140                if Present (Utyp) then
6141                   declare
6142                      Init : constant Entity_Id :=
6143                               (Find_Prim_Op
6144                                  (Underlying_Type (Typ), Name_Initialize));
6145
6146                   begin
6147                      if Present (Init)
6148                        and then Comes_From_Source (Init)
6149                        and then not
6150                          Is_Predefined_File_Name
6151                            (File_Name (Get_Source_File_Index (Sloc (Init))))
6152                      then
6153                         return True;
6154
6155                      elsif Has_Null_Extension (Typ)
6156                         and then
6157                           Is_Fully_Initialized_Type
6158                             (Etype (Base_Type (Typ)))
6159                      then
6160                         return True;
6161                      end if;
6162                   end;
6163                end if;
6164             end;
6165          end if;
6166
6167          --  Otherwise see if all record components are initialized
6168
6169          declare
6170             Ent : Entity_Id;
6171
6172          begin
6173             Ent := First_Entity (Typ);
6174             while Present (Ent) loop
6175                if Chars (Ent) = Name_uController then
6176                   null;
6177
6178                elsif Ekind (Ent) = E_Component
6179                  and then (No (Parent (Ent))
6180                              or else No (Expression (Parent (Ent))))
6181                  and then not Is_Fully_Initialized_Type (Etype (Ent))
6182
6183                   --  Special VM case for tag components, which need to be
6184                   --  defined in this case, but are never initialized as VMs
6185                   --  are using other dispatching mechanisms. Ignore this
6186                   --  uninitialized case. Note that this applies both to the
6187                   --  uTag entry and the main vtable pointer (CPP_Class case).
6188
6189                  and then (Tagged_Type_Expansion or else not Is_Tag (Ent))
6190                then
6191                   return False;
6192                end if;
6193
6194                Next_Entity (Ent);
6195             end loop;
6196          end;
6197
6198          --  No uninitialized components, so type is fully initialized.
6199          --  Note that this catches the case of no components as well.
6200
6201          return True;
6202
6203       elsif Is_Concurrent_Type (Typ) then
6204          return True;
6205
6206       elsif Is_Private_Type (Typ) then
6207          declare
6208             U : constant Entity_Id := Underlying_Type (Typ);
6209
6210          begin
6211             if No (U) then
6212                return False;
6213             else
6214                return Is_Fully_Initialized_Type (U);
6215             end if;
6216          end;
6217
6218       else
6219          return False;
6220       end if;
6221    end Is_Fully_Initialized_Type;
6222
6223    ----------------------------------
6224    -- Is_Fully_Initialized_Variant --
6225    ----------------------------------
6226
6227    function Is_Fully_Initialized_Variant (Typ : Entity_Id) return Boolean is
6228       Loc           : constant Source_Ptr := Sloc (Typ);
6229       Constraints   : constant List_Id    := New_List;
6230       Components    : constant Elist_Id   := New_Elmt_List;
6231       Comp_Elmt     : Elmt_Id;
6232       Comp_Id       : Node_Id;
6233       Comp_List     : Node_Id;
6234       Discr         : Entity_Id;
6235       Discr_Val     : Node_Id;
6236
6237       Report_Errors : Boolean;
6238       pragma Warnings (Off, Report_Errors);
6239
6240    begin
6241       if Serious_Errors_Detected > 0 then
6242          return False;
6243       end if;
6244
6245       if Is_Record_Type (Typ)
6246         and then Nkind (Parent (Typ)) = N_Full_Type_Declaration
6247         and then Nkind (Type_Definition (Parent (Typ))) = N_Record_Definition
6248       then
6249          Comp_List := Component_List (Type_Definition (Parent (Typ)));
6250
6251          Discr := First_Discriminant (Typ);
6252          while Present (Discr) loop
6253             if Nkind (Parent (Discr)) = N_Discriminant_Specification then
6254                Discr_Val := Expression (Parent (Discr));
6255
6256                if Present (Discr_Val)
6257                  and then Is_OK_Static_Expression (Discr_Val)
6258                then
6259                   Append_To (Constraints,
6260                     Make_Component_Association (Loc,
6261                       Choices    => New_List (New_Occurrence_Of (Discr, Loc)),
6262                       Expression => New_Copy (Discr_Val)));
6263                else
6264                   return False;
6265                end if;
6266             else
6267                return False;
6268             end if;
6269
6270             Next_Discriminant (Discr);
6271          end loop;
6272
6273          Gather_Components
6274            (Typ           => Typ,
6275             Comp_List     => Comp_List,
6276             Governed_By   => Constraints,
6277             Into          => Components,
6278             Report_Errors => Report_Errors);
6279
6280          --  Check that each component present is fully initialized
6281
6282          Comp_Elmt := First_Elmt (Components);
6283          while Present (Comp_Elmt) loop
6284             Comp_Id := Node (Comp_Elmt);
6285
6286             if Ekind (Comp_Id) = E_Component
6287               and then (No (Parent (Comp_Id))
6288                          or else No (Expression (Parent (Comp_Id))))
6289               and then not Is_Fully_Initialized_Type (Etype (Comp_Id))
6290             then
6291                return False;
6292             end if;
6293
6294             Next_Elmt (Comp_Elmt);
6295          end loop;
6296
6297          return True;
6298
6299       elsif Is_Private_Type (Typ) then
6300          declare
6301             U : constant Entity_Id := Underlying_Type (Typ);
6302
6303          begin
6304             if No (U) then
6305                return False;
6306             else
6307                return Is_Fully_Initialized_Variant (U);
6308             end if;
6309          end;
6310       else
6311          return False;
6312       end if;
6313    end Is_Fully_Initialized_Variant;
6314
6315    ------------
6316    -- Is_LHS --
6317    ------------
6318
6319    --  We seem to have a lot of overlapping functions that do similar things
6320    --  (testing for left hand sides or lvalues???). Anyway, since this one is
6321    --  purely syntactic, it should be in Sem_Aux I would think???
6322
6323    function Is_LHS (N : Node_Id) return Boolean is
6324       P : constant Node_Id := Parent (N);
6325    begin
6326       return Nkind (P) = N_Assignment_Statement
6327         and then Name (P) = N;
6328    end Is_LHS;
6329
6330    ----------------------------
6331    -- Is_Inherited_Operation --
6332    ----------------------------
6333
6334    function Is_Inherited_Operation (E : Entity_Id) return Boolean is
6335       Kind : constant Node_Kind := Nkind (Parent (E));
6336    begin
6337       pragma Assert (Is_Overloadable (E));
6338       return Kind = N_Full_Type_Declaration
6339         or else Kind = N_Private_Extension_Declaration
6340         or else Kind = N_Subtype_Declaration
6341         or else (Ekind (E) = E_Enumeration_Literal
6342                   and then Is_Derived_Type (Etype (E)));
6343    end Is_Inherited_Operation;
6344
6345    -----------------------------
6346    -- Is_Library_Level_Entity --
6347    -----------------------------
6348
6349    function Is_Library_Level_Entity (E : Entity_Id) return Boolean is
6350    begin
6351       --  The following is a small optimization, and it also properly handles
6352       --  discriminals, which in task bodies might appear in expressions before
6353       --  the corresponding procedure has been created, and which therefore do
6354       --  not have an assigned scope.
6355
6356       if Ekind (E) in Formal_Kind then
6357          return False;
6358       end if;
6359
6360       --  Normal test is simply that the enclosing dynamic scope is Standard
6361
6362       return Enclosing_Dynamic_Scope (E) = Standard_Standard;
6363    end Is_Library_Level_Entity;
6364
6365    ---------------------------------
6366    -- Is_Local_Variable_Reference --
6367    ---------------------------------
6368
6369    function Is_Local_Variable_Reference (Expr : Node_Id) return Boolean is
6370    begin
6371       if not Is_Entity_Name (Expr) then
6372          return False;
6373
6374       else
6375          declare
6376             Ent : constant Entity_Id := Entity (Expr);
6377             Sub : constant Entity_Id := Enclosing_Subprogram (Ent);
6378          begin
6379             if Ekind (Ent) /= E_Variable
6380                  and then
6381                Ekind (Ent) /= E_In_Out_Parameter
6382             then
6383                return False;
6384             else
6385                return Present (Sub) and then Sub = Current_Subprogram;
6386             end if;
6387          end;
6388       end if;
6389    end Is_Local_Variable_Reference;
6390
6391    -------------------------
6392    -- Is_Object_Reference --
6393    -------------------------
6394
6395    function Is_Object_Reference (N : Node_Id) return Boolean is
6396    begin
6397       if Is_Entity_Name (N) then
6398          return Present (Entity (N)) and then Is_Object (Entity (N));
6399
6400       else
6401          case Nkind (N) is
6402             when N_Indexed_Component | N_Slice =>
6403                return
6404                  Is_Object_Reference (Prefix (N))
6405                    or else Is_Access_Type (Etype (Prefix (N)));
6406
6407             --  In Ada95, a function call is a constant object; a procedure
6408             --  call is not.
6409
6410             when N_Function_Call =>
6411                return Etype (N) /= Standard_Void_Type;
6412
6413             --  A reference to the stream attribute Input is a function call
6414
6415             when N_Attribute_Reference =>
6416                return Attribute_Name (N) = Name_Input;
6417
6418             when N_Selected_Component =>
6419                return
6420                  Is_Object_Reference (Selector_Name (N))
6421                    and then
6422                      (Is_Object_Reference (Prefix (N))
6423                         or else Is_Access_Type (Etype (Prefix (N))));
6424
6425             when N_Explicit_Dereference =>
6426                return True;
6427
6428             --  A view conversion of a tagged object is an object reference
6429
6430             when N_Type_Conversion =>
6431                return Is_Tagged_Type (Etype (Subtype_Mark (N)))
6432                  and then Is_Tagged_Type (Etype (Expression (N)))
6433                  and then Is_Object_Reference (Expression (N));
6434
6435             --  An unchecked type conversion is considered to be an object if
6436             --  the operand is an object (this construction arises only as a
6437             --  result of expansion activities).
6438
6439             when N_Unchecked_Type_Conversion =>
6440                return True;
6441
6442             when others =>
6443                return False;
6444          end case;
6445       end if;
6446    end Is_Object_Reference;
6447
6448    -----------------------------------
6449    -- Is_OK_Variable_For_Out_Formal --
6450    -----------------------------------
6451
6452    function Is_OK_Variable_For_Out_Formal (AV : Node_Id) return Boolean is
6453    begin
6454       Note_Possible_Modification (AV, Sure => True);
6455
6456       --  We must reject parenthesized variable names. The check for
6457       --  Comes_From_Source is present because there are currently
6458       --  cases where the compiler violates this rule (e.g. passing
6459       --  a task object to its controlled Initialize routine).
6460
6461       if Paren_Count (AV) > 0 and then Comes_From_Source (AV) then
6462          return False;
6463
6464       --  A variable is always allowed
6465
6466       elsif Is_Variable (AV) then
6467          return True;
6468
6469       --  Unchecked conversions are allowed only if they come from the
6470       --  generated code, which sometimes uses unchecked conversions for out
6471       --  parameters in cases where code generation is unaffected. We tell
6472       --  source unchecked conversions by seeing if they are rewrites of an
6473       --  original Unchecked_Conversion function call, or of an explicit
6474       --  conversion of a function call.
6475
6476       elsif Nkind (AV) = N_Unchecked_Type_Conversion then
6477          if Nkind (Original_Node (AV)) = N_Function_Call then
6478             return False;
6479
6480          elsif Comes_From_Source (AV)
6481            and then Nkind (Original_Node (Expression (AV))) = N_Function_Call
6482          then
6483             return False;
6484
6485          elsif Nkind (Original_Node (AV)) = N_Type_Conversion then
6486             return Is_OK_Variable_For_Out_Formal (Expression (AV));
6487
6488          else
6489             return True;
6490          end if;
6491
6492       --  Normal type conversions are allowed if argument is a variable
6493
6494       elsif Nkind (AV) = N_Type_Conversion then
6495          if Is_Variable (Expression (AV))
6496            and then Paren_Count (Expression (AV)) = 0
6497          then
6498             Note_Possible_Modification (Expression (AV), Sure => True);
6499             return True;
6500
6501          --  We also allow a non-parenthesized expression that raises
6502          --  constraint error if it rewrites what used to be a variable
6503
6504          elsif Raises_Constraint_Error (Expression (AV))
6505             and then Paren_Count (Expression (AV)) = 0
6506             and then Is_Variable (Original_Node (Expression (AV)))
6507          then
6508             return True;
6509
6510          --  Type conversion of something other than a variable
6511
6512          else
6513             return False;
6514          end if;
6515
6516       --  If this node is rewritten, then test the original form, if that is
6517       --  OK, then we consider the rewritten node OK (for example, if the
6518       --  original node is a conversion, then Is_Variable will not be true
6519       --  but we still want to allow the conversion if it converts a variable).
6520
6521       elsif Original_Node (AV) /= AV then
6522          return Is_OK_Variable_For_Out_Formal (Original_Node (AV));
6523
6524       --  All other non-variables are rejected
6525
6526       else
6527          return False;
6528       end if;
6529    end Is_OK_Variable_For_Out_Formal;
6530
6531    -----------------------------------
6532    -- Is_Partially_Initialized_Type --
6533    -----------------------------------
6534
6535    function Is_Partially_Initialized_Type (Typ : Entity_Id) return Boolean is
6536    begin
6537       if Is_Scalar_Type (Typ) then
6538          return False;
6539
6540       elsif Is_Access_Type (Typ) then
6541          return True;
6542
6543       elsif Is_Array_Type (Typ) then
6544
6545          --  If component type is partially initialized, so is array type
6546
6547          if Is_Partially_Initialized_Type (Component_Type (Typ)) then
6548             return True;
6549
6550          --  Otherwise we are only partially initialized if we are fully
6551          --  initialized (this is the empty array case, no point in us
6552          --  duplicating that code here).
6553
6554          else
6555             return Is_Fully_Initialized_Type (Typ);
6556          end if;
6557
6558       elsif Is_Record_Type (Typ) then
6559
6560          --  A discriminated type is always partially initialized
6561
6562          if Has_Discriminants (Typ) then
6563             return True;
6564
6565          --  A tagged type is always partially initialized
6566
6567          elsif Is_Tagged_Type (Typ) then
6568             return True;
6569
6570          --  Case of non-discriminated record
6571
6572          else
6573             declare
6574                Ent : Entity_Id;
6575
6576                Component_Present : Boolean := False;
6577                --  Set True if at least one component is present. If no
6578                --  components are present, then record type is fully
6579                --  initialized (another odd case, like the null array).
6580
6581             begin
6582                --  Loop through components
6583
6584                Ent := First_Entity (Typ);
6585                while Present (Ent) loop
6586                   if Ekind (Ent) = E_Component then
6587                      Component_Present := True;
6588
6589                      --  If a component has an initialization expression then
6590                      --  the enclosing record type is partially initialized
6591
6592                      if Present (Parent (Ent))
6593                        and then Present (Expression (Parent (Ent)))
6594                      then
6595                         return True;
6596
6597                      --  If a component is of a type which is itself partially
6598                      --  initialized, then the enclosing record type is also.
6599
6600                      elsif Is_Partially_Initialized_Type (Etype (Ent)) then
6601                         return True;
6602                      end if;
6603                   end if;
6604
6605                   Next_Entity (Ent);
6606                end loop;
6607
6608                --  No initialized components found. If we found any components
6609                --  they were all uninitialized so the result is false.
6610
6611                if Component_Present then
6612                   return False;
6613
6614                --  But if we found no components, then all the components are
6615                --  initialized so we consider the type to be initialized.
6616
6617                else
6618                   return True;
6619                end if;
6620             end;
6621          end if;
6622
6623       --  Concurrent types are always fully initialized
6624
6625       elsif Is_Concurrent_Type (Typ) then
6626          return True;
6627
6628       --  For a private type, go to underlying type. If there is no underlying
6629       --  type then just assume this partially initialized. Not clear if this
6630       --  can happen in a non-error case, but no harm in testing for this.
6631
6632       elsif Is_Private_Type (Typ) then
6633          declare
6634             U : constant Entity_Id := Underlying_Type (Typ);
6635          begin
6636             if No (U) then
6637                return True;
6638             else
6639                return Is_Partially_Initialized_Type (U);
6640             end if;
6641          end;
6642
6643       --  For any other type (are there any?) assume partially initialized
6644
6645       else
6646          return True;
6647       end if;
6648    end Is_Partially_Initialized_Type;
6649
6650    ------------------------------------
6651    -- Is_Potentially_Persistent_Type --
6652    ------------------------------------
6653
6654    function Is_Potentially_Persistent_Type (T : Entity_Id) return Boolean is
6655       Comp : Entity_Id;
6656       Indx : Node_Id;
6657
6658    begin
6659       --  For private type, test corresponding full type
6660
6661       if Is_Private_Type (T) then
6662          return Is_Potentially_Persistent_Type (Full_View (T));
6663
6664       --  Scalar types are potentially persistent
6665
6666       elsif Is_Scalar_Type (T) then
6667          return True;
6668
6669       --  Record type is potentially persistent if not tagged and the types of
6670       --  all it components are potentially persistent, and no component has
6671       --  an initialization expression.
6672
6673       elsif Is_Record_Type (T)
6674         and then not Is_Tagged_Type (T)
6675         and then not Is_Partially_Initialized_Type (T)
6676       then
6677          Comp := First_Component (T);
6678          while Present (Comp) loop
6679             if not Is_Potentially_Persistent_Type (Etype (Comp)) then
6680                return False;
6681             else
6682                Next_Entity (Comp);
6683             end if;
6684          end loop;
6685
6686          return True;
6687
6688       --  Array type is potentially persistent if its component type is
6689       --  potentially persistent and if all its constraints are static.
6690
6691       elsif Is_Array_Type (T) then
6692          if not Is_Potentially_Persistent_Type (Component_Type (T)) then
6693             return False;
6694          end if;
6695
6696          Indx := First_Index (T);
6697          while Present (Indx) loop
6698             if not Is_OK_Static_Subtype (Etype (Indx)) then
6699                return False;
6700             else
6701                Next_Index (Indx);
6702             end if;
6703          end loop;
6704
6705          return True;
6706
6707       --  All other types are not potentially persistent
6708
6709       else
6710          return False;
6711       end if;
6712    end Is_Potentially_Persistent_Type;
6713
6714    ---------------------------------
6715    -- Is_Protected_Self_Reference --
6716    ---------------------------------
6717
6718    function Is_Protected_Self_Reference (N : Node_Id) return Boolean is
6719
6720       function In_Access_Definition (N : Node_Id) return Boolean;
6721       --  Returns true if N belongs to an access definition
6722
6723       --------------------------
6724       -- In_Access_Definition --
6725       --------------------------
6726
6727       function In_Access_Definition (N : Node_Id) return Boolean is
6728          P : Node_Id;
6729
6730       begin
6731          P := Parent (N);
6732          while Present (P) loop
6733             if Nkind (P) = N_Access_Definition then
6734                return True;
6735             end if;
6736
6737             P := Parent (P);
6738          end loop;
6739
6740          return False;
6741       end In_Access_Definition;
6742
6743    --  Start of processing for Is_Protected_Self_Reference
6744
6745    begin
6746       --  Verify that prefix is analyzed and has the proper form. Note that
6747       --  the attributes Elab_Spec, Elab_Body, and UET_Address, which also
6748       --  produce the address of an entity, do not analyze their prefix
6749       --  because they denote entities that are not necessarily visible.
6750       --  Neither of them can apply to a protected type.
6751
6752       return Ada_Version >= Ada_05
6753         and then Is_Entity_Name (N)
6754         and then Present (Entity (N))
6755         and then Is_Protected_Type (Entity (N))
6756         and then In_Open_Scopes (Entity (N))
6757         and then not In_Access_Definition (N);
6758    end Is_Protected_Self_Reference;
6759
6760    -----------------------------
6761    -- Is_RCI_Pkg_Spec_Or_Body --
6762    -----------------------------
6763
6764    function Is_RCI_Pkg_Spec_Or_Body (Cunit : Node_Id) return Boolean is
6765
6766       function Is_RCI_Pkg_Decl_Cunit (Cunit : Node_Id) return Boolean;
6767       --  Return True if the unit of Cunit is an RCI package declaration
6768
6769       ---------------------------
6770       -- Is_RCI_Pkg_Decl_Cunit --
6771       ---------------------------
6772
6773       function Is_RCI_Pkg_Decl_Cunit (Cunit : Node_Id) return Boolean is
6774          The_Unit : constant Node_Id := Unit (Cunit);
6775
6776       begin
6777          if Nkind (The_Unit) /= N_Package_Declaration then
6778             return False;
6779          end if;
6780
6781          return Is_Remote_Call_Interface (Defining_Entity (The_Unit));
6782       end Is_RCI_Pkg_Decl_Cunit;
6783
6784    --  Start of processing for Is_RCI_Pkg_Spec_Or_Body
6785
6786    begin
6787       return Is_RCI_Pkg_Decl_Cunit (Cunit)
6788         or else
6789          (Nkind (Unit (Cunit)) = N_Package_Body
6790            and then Is_RCI_Pkg_Decl_Cunit (Library_Unit (Cunit)));
6791    end Is_RCI_Pkg_Spec_Or_Body;
6792
6793    -----------------------------------------
6794    -- Is_Remote_Access_To_Class_Wide_Type --
6795    -----------------------------------------
6796
6797    function Is_Remote_Access_To_Class_Wide_Type
6798      (E : Entity_Id) return Boolean
6799    is
6800    begin
6801       --  A remote access to class-wide type is a general access to object type
6802       --  declared in the visible part of a Remote_Types or Remote_Call_
6803       --  Interface unit.
6804
6805       return Ekind (E) = E_General_Access_Type
6806         and then (Is_Remote_Call_Interface (E) or else Is_Remote_Types (E));
6807    end Is_Remote_Access_To_Class_Wide_Type;
6808
6809    -----------------------------------------
6810    -- Is_Remote_Access_To_Subprogram_Type --
6811    -----------------------------------------
6812
6813    function Is_Remote_Access_To_Subprogram_Type
6814      (E : Entity_Id) return Boolean
6815    is
6816    begin
6817       return (Ekind (E) = E_Access_Subprogram_Type
6818                 or else (Ekind (E) = E_Record_Type
6819                            and then Present (Corresponding_Remote_Type (E))))
6820         and then (Is_Remote_Call_Interface (E) or else Is_Remote_Types (E));
6821    end Is_Remote_Access_To_Subprogram_Type;
6822
6823    --------------------
6824    -- Is_Remote_Call --
6825    --------------------
6826
6827    function Is_Remote_Call (N : Node_Id) return Boolean is
6828    begin
6829       if Nkind (N) /= N_Procedure_Call_Statement
6830         and then Nkind (N) /= N_Function_Call
6831       then
6832          --  An entry call cannot be remote
6833
6834          return False;
6835
6836       elsif Nkind (Name (N)) in N_Has_Entity
6837         and then Is_Remote_Call_Interface (Entity (Name (N)))
6838       then
6839          --  A subprogram declared in the spec of a RCI package is remote
6840
6841          return True;
6842
6843       elsif Nkind (Name (N)) = N_Explicit_Dereference
6844         and then Is_Remote_Access_To_Subprogram_Type
6845                    (Etype (Prefix (Name (N))))
6846       then
6847          --  The dereference of a RAS is a remote call
6848
6849          return True;
6850
6851       elsif Present (Controlling_Argument (N))
6852         and then Is_Remote_Access_To_Class_Wide_Type
6853           (Etype (Controlling_Argument (N)))
6854       then
6855          --  Any primitive operation call with a controlling argument of
6856          --  a RACW type is a remote call.
6857
6858          return True;
6859       end if;
6860
6861       --  All other calls are local calls
6862
6863       return False;
6864    end Is_Remote_Call;
6865
6866    ----------------------
6867    -- Is_Renamed_Entry --
6868    ----------------------
6869
6870    function Is_Renamed_Entry (Proc_Nam : Entity_Id) return Boolean is
6871       Orig_Node : Node_Id := Empty;
6872       Subp_Decl : Node_Id := Parent (Parent (Proc_Nam));
6873
6874       function Is_Entry (Nam : Node_Id) return Boolean;
6875       --  Determine whether Nam is an entry. Traverse selectors if there are
6876       --  nested selected components.
6877
6878       --------------
6879       -- Is_Entry --
6880       --------------
6881
6882       function Is_Entry (Nam : Node_Id) return Boolean is
6883       begin
6884          if Nkind (Nam) = N_Selected_Component then
6885             return Is_Entry (Selector_Name (Nam));
6886          end if;
6887
6888          return Ekind (Entity (Nam)) = E_Entry;
6889       end Is_Entry;
6890
6891    --  Start of processing for Is_Renamed_Entry
6892
6893    begin
6894       if Present (Alias (Proc_Nam)) then
6895          Subp_Decl := Parent (Parent (Alias (Proc_Nam)));
6896       end if;
6897
6898       --  Look for a rewritten subprogram renaming declaration
6899
6900       if Nkind (Subp_Decl) = N_Subprogram_Declaration
6901         and then Present (Original_Node (Subp_Decl))
6902       then
6903          Orig_Node := Original_Node (Subp_Decl);
6904       end if;
6905
6906       --  The rewritten subprogram is actually an entry
6907
6908       if Present (Orig_Node)
6909         and then Nkind (Orig_Node) = N_Subprogram_Renaming_Declaration
6910         and then Is_Entry (Name (Orig_Node))
6911       then
6912          return True;
6913       end if;
6914
6915       return False;
6916    end Is_Renamed_Entry;
6917
6918    ----------------------
6919    -- Is_Selector_Name --
6920    ----------------------
6921
6922    function Is_Selector_Name (N : Node_Id) return Boolean is
6923    begin
6924       if not Is_List_Member (N) then
6925          declare
6926             P : constant Node_Id   := Parent (N);
6927             K : constant Node_Kind := Nkind (P);
6928          begin
6929             return
6930               (K = N_Expanded_Name          or else
6931                K = N_Generic_Association    or else
6932                K = N_Parameter_Association  or else
6933                K = N_Selected_Component)
6934               and then Selector_Name (P) = N;
6935          end;
6936
6937       else
6938          declare
6939             L : constant List_Id := List_Containing (N);
6940             P : constant Node_Id := Parent (L);
6941          begin
6942             return (Nkind (P) = N_Discriminant_Association
6943                      and then Selector_Names (P) = L)
6944               or else
6945                    (Nkind (P) = N_Component_Association
6946                      and then Choices (P) = L);
6947          end;
6948       end if;
6949    end Is_Selector_Name;
6950
6951    ------------------
6952    -- Is_Statement --
6953    ------------------
6954
6955    function Is_Statement (N : Node_Id) return Boolean is
6956    begin
6957       return
6958         Nkind (N) in N_Statement_Other_Than_Procedure_Call
6959           or else Nkind (N) = N_Procedure_Call_Statement;
6960    end Is_Statement;
6961
6962    ---------------------------------
6963    -- Is_Synchronized_Tagged_Type --
6964    ---------------------------------
6965
6966    function Is_Synchronized_Tagged_Type (E : Entity_Id) return Boolean is
6967       Kind : constant Entity_Kind := Ekind (Base_Type (E));
6968
6969    begin
6970       --  A task or protected type derived from an interface is a tagged type.
6971       --  Such a tagged type is called a synchronized tagged type, as are
6972       --  synchronized interfaces and private extensions whose declaration
6973       --  includes the reserved word synchronized.
6974
6975       return (Is_Tagged_Type (E)
6976                 and then (Kind = E_Task_Type
6977                            or else Kind = E_Protected_Type))
6978             or else
6979              (Is_Interface (E)
6980                 and then Is_Synchronized_Interface (E))
6981             or else
6982              (Ekind (E) = E_Record_Type_With_Private
6983                 and then (Synchronized_Present (Parent (E))
6984                            or else Is_Synchronized_Interface (Etype (E))));
6985    end Is_Synchronized_Tagged_Type;
6986
6987    -----------------
6988    -- Is_Transfer --
6989    -----------------
6990
6991    function Is_Transfer (N : Node_Id) return Boolean is
6992       Kind : constant Node_Kind := Nkind (N);
6993
6994    begin
6995       if Kind = N_Simple_Return_Statement
6996            or else
6997          Kind = N_Extended_Return_Statement
6998            or else
6999          Kind = N_Goto_Statement
7000            or else
7001          Kind = N_Raise_Statement
7002            or else
7003          Kind = N_Requeue_Statement
7004       then
7005          return True;
7006
7007       elsif (Kind = N_Exit_Statement or else Kind in N_Raise_xxx_Error)
7008         and then No (Condition (N))
7009       then
7010          return True;
7011
7012       elsif Kind = N_Procedure_Call_Statement
7013         and then Is_Entity_Name (Name (N))
7014         and then Present (Entity (Name (N)))
7015         and then No_Return (Entity (Name (N)))
7016       then
7017          return True;
7018
7019       elsif Nkind (Original_Node (N)) = N_Raise_Statement then
7020          return True;
7021
7022       else
7023          return False;
7024       end if;
7025    end Is_Transfer;
7026
7027    -------------
7028    -- Is_True --
7029    -------------
7030
7031    function Is_True (U : Uint) return Boolean is
7032    begin
7033       return (U /= 0);
7034    end Is_True;
7035
7036    -------------------
7037    -- Is_Value_Type --
7038    -------------------
7039
7040    function Is_Value_Type (T : Entity_Id) return Boolean is
7041    begin
7042       return VM_Target = CLI_Target
7043         and then Nkind (T) in N_Has_Chars
7044         and then Chars (T) /= No_Name
7045         and then Get_Name_String (Chars (T)) = "valuetype";
7046    end Is_Value_Type;
7047
7048    ---------------------
7049    -- Is_VMS_Operator --
7050    ---------------------
7051
7052    function Is_VMS_Operator (Op : Entity_Id) return Boolean is
7053    begin
7054       return Ekind (Op) = E_Function
7055         and then Is_Intrinsic_Subprogram (Op)
7056         and then Scope (Op) = System_Aux_Id;
7057    end Is_VMS_Operator;
7058
7059    -----------------
7060    -- Is_Delegate --
7061    -----------------
7062
7063    function Is_Delegate (T : Entity_Id) return Boolean is
7064       Desig_Type : Entity_Id;
7065
7066    begin
7067       if VM_Target /= CLI_Target then
7068          return False;
7069       end if;
7070
7071       --  Access-to-subprograms are delegates in CIL
7072
7073       if Ekind (T) = E_Access_Subprogram_Type then
7074          return True;
7075       end if;
7076
7077       if Ekind (T) not in Access_Kind then
7078
7079          --  A delegate is a managed pointer. If no designated type is defined
7080          --  it means that it's not a delegate.
7081
7082          return False;
7083       end if;
7084
7085       Desig_Type := Etype (Directly_Designated_Type (T));
7086
7087       if not Is_Tagged_Type (Desig_Type) then
7088          return False;
7089       end if;
7090
7091       --  Test if the type is inherited from [mscorlib]System.Delegate
7092
7093       while Etype (Desig_Type) /= Desig_Type loop
7094          if Chars (Scope (Desig_Type)) /= No_Name
7095            and then Is_Imported (Scope (Desig_Type))
7096            and then Get_Name_String (Chars (Scope (Desig_Type))) = "delegate"
7097          then
7098             return True;
7099          end if;
7100
7101          Desig_Type := Etype (Desig_Type);
7102       end loop;
7103
7104       return False;
7105    end Is_Delegate;
7106
7107    -----------------
7108    -- Is_Variable --
7109    -----------------
7110
7111    function Is_Variable (N : Node_Id) return Boolean is
7112
7113       Orig_Node : constant Node_Id := Original_Node (N);
7114       --  We do the test on the original node, since this is basically a test
7115       --  of syntactic categories, so it must not be disturbed by whatever
7116       --  rewriting might have occurred. For example, an aggregate, which is
7117       --  certainly NOT a variable, could be turned into a variable by
7118       --  expansion.
7119
7120       function In_Protected_Function (E : Entity_Id) return Boolean;
7121       --  Within a protected function, the private components of the
7122       --  enclosing protected type are constants. A function nested within
7123       --  a (protected) procedure is not itself protected.
7124
7125       function Is_Variable_Prefix (P : Node_Id) return Boolean;
7126       --  Prefixes can involve implicit dereferences, in which case we
7127       --  must test for the case of a reference of a constant access
7128       --  type, which can never be a variable.
7129
7130       ---------------------------
7131       -- In_Protected_Function --
7132       ---------------------------
7133
7134       function In_Protected_Function (E : Entity_Id) return Boolean is
7135          Prot : constant Entity_Id := Scope (E);
7136          S    : Entity_Id;
7137
7138       begin
7139          if not Is_Protected_Type (Prot) then
7140             return False;
7141          else
7142             S := Current_Scope;
7143             while Present (S) and then S /= Prot loop
7144                if Ekind (S) = E_Function
7145                  and then Scope (S) = Prot
7146                then
7147                   return True;
7148                end if;
7149
7150                S := Scope (S);
7151             end loop;
7152
7153             return False;
7154          end if;
7155       end In_Protected_Function;
7156
7157       ------------------------
7158       -- Is_Variable_Prefix --
7159       ------------------------
7160
7161       function Is_Variable_Prefix (P : Node_Id) return Boolean is
7162       begin
7163          if Is_Access_Type (Etype (P)) then
7164             return not Is_Access_Constant (Root_Type (Etype (P)));
7165
7166          --  For the case of an indexed component whose prefix has a packed
7167          --  array type, the prefix has been rewritten into a type conversion.
7168          --  Determine variable-ness from the converted expression.
7169
7170          elsif Nkind (P) = N_Type_Conversion
7171            and then not Comes_From_Source (P)
7172            and then Is_Array_Type (Etype (P))
7173            and then Is_Packed (Etype (P))
7174          then
7175             return Is_Variable (Expression (P));
7176
7177          else
7178             return Is_Variable (P);
7179          end if;
7180       end Is_Variable_Prefix;
7181
7182    --  Start of processing for Is_Variable
7183
7184    begin
7185       --  Definitely OK if Assignment_OK is set. Since this is something that
7186       --  only gets set for expanded nodes, the test is on N, not Orig_Node.
7187
7188       if Nkind (N) in N_Subexpr and then Assignment_OK (N) then
7189          return True;
7190
7191       --  Normally we go to the original node, but there is one exception
7192       --  where we use the rewritten node, namely when it is an explicit
7193       --  dereference. The generated code may rewrite a prefix which is an
7194       --  access type with an explicit dereference. The dereference is a
7195       --  variable, even though the original node may not be (since it could
7196       --  be a constant of the access type).
7197
7198       --  In Ada 2005 we have a further case to consider: the prefix may be
7199       --  a function call given in prefix notation. The original node appears
7200       --  to be a selected component, but we need to examine the call.
7201
7202       elsif Nkind (N) = N_Explicit_Dereference
7203         and then Nkind (Orig_Node) /= N_Explicit_Dereference
7204         and then Present (Etype (Orig_Node))
7205         and then Is_Access_Type (Etype (Orig_Node))
7206       then
7207          --  Note that if the prefix is an explicit dereference that does not
7208          --  come from source, we must check for a rewritten function call in
7209          --  prefixed notation before other forms of rewriting, to prevent a
7210          --  compiler crash.
7211
7212          return
7213            (Nkind (Orig_Node) = N_Function_Call
7214              and then not Is_Access_Constant (Etype (Prefix (N))))
7215            or else
7216              Is_Variable_Prefix (Original_Node (Prefix (N)));
7217
7218       --  A function call is never a variable
7219
7220       elsif Nkind (N) = N_Function_Call then
7221          return False;
7222
7223       --  All remaining checks use the original node
7224
7225       elsif Is_Entity_Name (Orig_Node)
7226         and then Present (Entity (Orig_Node))
7227       then
7228          declare
7229             E : constant Entity_Id := Entity (Orig_Node);
7230             K : constant Entity_Kind := Ekind (E);
7231
7232          begin
7233             return (K = E_Variable
7234                       and then Nkind (Parent (E)) /= N_Exception_Handler)
7235               or else  (K = E_Component
7236                           and then not In_Protected_Function (E))
7237               or else  K = E_Out_Parameter
7238               or else  K = E_In_Out_Parameter
7239               or else  K = E_Generic_In_Out_Parameter
7240
7241                --  Current instance of type:
7242
7243               or else (Is_Type (E) and then In_Open_Scopes (E))
7244               or else (Is_Incomplete_Or_Private_Type (E)
7245                         and then In_Open_Scopes (Full_View (E)));
7246          end;
7247
7248       else
7249          case Nkind (Orig_Node) is
7250             when N_Indexed_Component | N_Slice =>
7251                return Is_Variable_Prefix (Prefix (Orig_Node));
7252
7253             when N_Selected_Component =>
7254                return Is_Variable_Prefix (Prefix (Orig_Node))
7255                  and then Is_Variable (Selector_Name (Orig_Node));
7256
7257             --  For an explicit dereference, the type of the prefix cannot
7258             --  be an access to constant or an access to subprogram.
7259
7260             when N_Explicit_Dereference =>
7261                declare
7262                   Typ : constant Entity_Id := Etype (Prefix (Orig_Node));
7263                begin
7264                   return Is_Access_Type (Typ)
7265                     and then not Is_Access_Constant (Root_Type (Typ))
7266                     and then Ekind (Typ) /= E_Access_Subprogram_Type;
7267                end;
7268
7269             --  The type conversion is the case where we do not deal with the
7270             --  context dependent special case of an actual parameter. Thus
7271             --  the type conversion is only considered a variable for the
7272             --  purposes of this routine if the target type is tagged. However,
7273             --  a type conversion is considered to be a variable if it does not
7274             --  come from source (this deals for example with the conversions
7275             --  of expressions to their actual subtypes).
7276
7277             when N_Type_Conversion =>
7278                return Is_Variable (Expression (Orig_Node))
7279                  and then
7280                    (not Comes_From_Source (Orig_Node)
7281                       or else
7282                         (Is_Tagged_Type (Etype (Subtype_Mark (Orig_Node)))
7283                           and then
7284                          Is_Tagged_Type (Etype (Expression (Orig_Node)))));
7285
7286             --  GNAT allows an unchecked type conversion as a variable. This
7287             --  only affects the generation of internal expanded code, since
7288             --  calls to instantiations of Unchecked_Conversion are never
7289             --  considered variables (since they are function calls).
7290             --  This is also true for expression actions.
7291
7292             when N_Unchecked_Type_Conversion =>
7293                return Is_Variable (Expression (Orig_Node));
7294
7295             when others =>
7296                return False;
7297          end case;
7298       end if;
7299    end Is_Variable;
7300
7301    ---------------------------
7302    -- Is_Visibly_Controlled --
7303    ---------------------------
7304
7305    function Is_Visibly_Controlled (T : Entity_Id) return Boolean is
7306       Root : constant Entity_Id := Root_Type (T);
7307    begin
7308       return Chars (Scope (Root)) = Name_Finalization
7309         and then Chars (Scope (Scope (Root))) = Name_Ada
7310         and then Scope (Scope (Scope (Root))) = Standard_Standard;
7311    end Is_Visibly_Controlled;
7312
7313    ------------------------
7314    -- Is_Volatile_Object --
7315    ------------------------
7316
7317    function Is_Volatile_Object (N : Node_Id) return Boolean is
7318
7319       function Object_Has_Volatile_Components (N : Node_Id) return Boolean;
7320       --  Determines if given object has volatile components
7321
7322       function Is_Volatile_Prefix (N : Node_Id) return Boolean;
7323       --  If prefix is an implicit dereference, examine designated type
7324
7325       ------------------------
7326       -- Is_Volatile_Prefix --
7327       ------------------------
7328
7329       function Is_Volatile_Prefix (N : Node_Id) return Boolean is
7330          Typ  : constant Entity_Id := Etype (N);
7331
7332       begin
7333          if Is_Access_Type (Typ) then
7334             declare
7335                Dtyp : constant Entity_Id := Designated_Type (Typ);
7336
7337             begin
7338                return Is_Volatile (Dtyp)
7339                  or else Has_Volatile_Components (Dtyp);
7340             end;
7341
7342          else
7343             return Object_Has_Volatile_Components (N);
7344          end if;
7345       end Is_Volatile_Prefix;
7346
7347       ------------------------------------
7348       -- Object_Has_Volatile_Components --
7349       ------------------------------------
7350
7351       function Object_Has_Volatile_Components (N : Node_Id) return Boolean is
7352          Typ : constant Entity_Id := Etype (N);
7353
7354       begin
7355          if Is_Volatile (Typ)
7356            or else Has_Volatile_Components (Typ)
7357          then
7358             return True;
7359
7360          elsif Is_Entity_Name (N)
7361            and then (Has_Volatile_Components (Entity (N))
7362                       or else Is_Volatile (Entity (N)))
7363          then
7364             return True;
7365
7366          elsif Nkind (N) = N_Indexed_Component
7367            or else Nkind (N) = N_Selected_Component
7368          then
7369             return Is_Volatile_Prefix (Prefix (N));
7370
7371          else
7372             return False;
7373          end if;
7374       end Object_Has_Volatile_Components;
7375
7376    --  Start of processing for Is_Volatile_Object
7377
7378    begin
7379       if Is_Volatile (Etype (N))
7380         or else (Is_Entity_Name (N) and then Is_Volatile (Entity (N)))
7381       then
7382          return True;
7383
7384       elsif Nkind (N) = N_Indexed_Component
7385         or else Nkind (N) = N_Selected_Component
7386       then
7387          return Is_Volatile_Prefix (Prefix (N));
7388
7389       else
7390          return False;
7391       end if;
7392    end Is_Volatile_Object;
7393
7394    -------------------------
7395    -- Kill_Current_Values --
7396    -------------------------
7397
7398    procedure Kill_Current_Values
7399      (Ent                  : Entity_Id;
7400       Last_Assignment_Only : Boolean := False)
7401    is
7402    begin
7403       --  ??? do we have to worry about clearing cached checks?
7404
7405       if Is_Assignable (Ent) then
7406          Set_Last_Assignment (Ent, Empty);
7407       end if;
7408
7409       if Is_Object (Ent) then
7410          if not Last_Assignment_Only then
7411             Kill_Checks (Ent);
7412             Set_Current_Value (Ent, Empty);
7413
7414             if not Can_Never_Be_Null (Ent) then
7415                Set_Is_Known_Non_Null (Ent, False);
7416             end if;
7417
7418             Set_Is_Known_Null (Ent, False);
7419
7420             --  Reset Is_Known_Valid unless type is always valid, or if we have
7421             --  a loop parameter (loop parameters are always valid, since their
7422             --  bounds are defined by the bounds given in the loop header).
7423
7424             if not Is_Known_Valid (Etype (Ent))
7425               and then Ekind (Ent) /= E_Loop_Parameter
7426             then
7427                Set_Is_Known_Valid (Ent, False);
7428             end if;
7429          end if;
7430       end if;
7431    end Kill_Current_Values;
7432
7433    procedure Kill_Current_Values (Last_Assignment_Only : Boolean := False) is
7434       S : Entity_Id;
7435
7436       procedure Kill_Current_Values_For_Entity_Chain (E : Entity_Id);
7437       --  Clear current value for entity E and all entities chained to E
7438
7439       ------------------------------------------
7440       -- Kill_Current_Values_For_Entity_Chain --
7441       ------------------------------------------
7442
7443       procedure Kill_Current_Values_For_Entity_Chain (E : Entity_Id) is
7444          Ent : Entity_Id;
7445       begin
7446          Ent := E;
7447          while Present (Ent) loop
7448             Kill_Current_Values (Ent, Last_Assignment_Only);
7449             Next_Entity (Ent);
7450          end loop;
7451       end Kill_Current_Values_For_Entity_Chain;
7452
7453    --  Start of processing for Kill_Current_Values
7454
7455    begin
7456       --  Kill all saved checks, a special case of killing saved values
7457
7458       if not Last_Assignment_Only then
7459          Kill_All_Checks;
7460       end if;
7461
7462       --  Loop through relevant scopes, which includes the current scope and
7463       --  any parent scopes if the current scope is a block or a package.
7464
7465       S := Current_Scope;
7466       Scope_Loop : loop
7467
7468          --  Clear current values of all entities in current scope
7469
7470          Kill_Current_Values_For_Entity_Chain (First_Entity (S));
7471
7472          --  If scope is a package, also clear current values of all
7473          --  private entities in the scope.
7474
7475          if Is_Package_Or_Generic_Package (S)
7476            or else Is_Concurrent_Type (S)
7477          then
7478             Kill_Current_Values_For_Entity_Chain (First_Private_Entity (S));
7479          end if;
7480
7481          --  If this is a not a subprogram, deal with parents
7482
7483          if not Is_Subprogram (S) then
7484             S := Scope (S);
7485             exit Scope_Loop when S = Standard_Standard;
7486          else
7487             exit Scope_Loop;
7488          end if;
7489       end loop Scope_Loop;
7490    end Kill_Current_Values;
7491
7492    --------------------------
7493    -- Kill_Size_Check_Code --
7494    --------------------------
7495
7496    procedure Kill_Size_Check_Code (E : Entity_Id) is
7497    begin
7498       if (Ekind (E) = E_Constant or else Ekind (E) = E_Variable)
7499         and then Present (Size_Check_Code (E))
7500       then
7501          Remove (Size_Check_Code (E));
7502          Set_Size_Check_Code (E, Empty);
7503       end if;
7504    end Kill_Size_Check_Code;
7505
7506    --------------------------
7507    -- Known_To_Be_Assigned --
7508    --------------------------
7509
7510    function Known_To_Be_Assigned (N : Node_Id) return Boolean is
7511       P : constant Node_Id := Parent (N);
7512
7513    begin
7514       case Nkind (P) is
7515
7516          --  Test left side of assignment
7517
7518          when N_Assignment_Statement =>
7519             return N = Name (P);
7520
7521             --  Function call arguments are never lvalues
7522
7523          when N_Function_Call =>
7524             return False;
7525
7526          --  Positional parameter for procedure or accept call
7527
7528          when N_Procedure_Call_Statement |
7529               N_Accept_Statement
7530           =>
7531             declare
7532                Proc : Entity_Id;
7533                Form : Entity_Id;
7534                Act  : Node_Id;
7535
7536             begin
7537                Proc := Get_Subprogram_Entity (P);
7538
7539                if No (Proc) then
7540                   return False;
7541                end if;
7542
7543                --  If we are not a list member, something is strange, so
7544                --  be conservative and return False.
7545
7546                if not Is_List_Member (N) then
7547                   return False;
7548                end if;
7549
7550                --  We are going to find the right formal by stepping forward
7551                --  through the formals, as we step backwards in the actuals.
7552
7553                Form := First_Formal (Proc);
7554                Act  := N;
7555                loop
7556                   --  If no formal, something is weird, so be conservative
7557                   --  and return False.
7558
7559                   if No (Form) then
7560                      return False;
7561                   end if;
7562
7563                   Prev (Act);
7564                   exit when No (Act);
7565                   Next_Formal (Form);
7566                end loop;
7567
7568                return Ekind (Form) /= E_In_Parameter;
7569             end;
7570
7571          --  Named parameter for procedure or accept call
7572
7573          when N_Parameter_Association =>
7574             declare
7575                Proc : Entity_Id;
7576                Form : Entity_Id;
7577
7578             begin
7579                Proc := Get_Subprogram_Entity (Parent (P));
7580
7581                if No (Proc) then
7582                   return False;
7583                end if;
7584
7585                --  Loop through formals to find the one that matches
7586
7587                Form := First_Formal (Proc);
7588                loop
7589                   --  If no matching formal, that's peculiar, some kind of
7590                   --  previous error, so return False to be conservative.
7591
7592                   if No (Form) then
7593                      return False;
7594                   end if;
7595
7596                   --  Else test for match
7597
7598                   if Chars (Form) = Chars (Selector_Name (P)) then
7599                      return Ekind (Form) /= E_In_Parameter;
7600                   end if;
7601
7602                   Next_Formal (Form);
7603                end loop;
7604             end;
7605
7606          --  Test for appearing in a conversion that itself appears
7607          --  in an lvalue context, since this should be an lvalue.
7608
7609          when N_Type_Conversion =>
7610             return Known_To_Be_Assigned (P);
7611
7612          --  All other references are definitely not known to be modifications
7613
7614          when others =>
7615             return False;
7616
7617       end case;
7618    end Known_To_Be_Assigned;
7619
7620    -------------------
7621    -- May_Be_Lvalue --
7622    -------------------
7623
7624    function May_Be_Lvalue (N : Node_Id) return Boolean is
7625       P : constant Node_Id := Parent (N);
7626
7627    begin
7628       case Nkind (P) is
7629
7630          --  Test left side of assignment
7631
7632          when N_Assignment_Statement =>
7633             return N = Name (P);
7634
7635          --  Test prefix of component or attribute. Note that the prefix of an
7636          --  explicit or implicit dereference cannot be an l-value.
7637
7638          when N_Attribute_Reference =>
7639             return N = Prefix (P)
7640               and then Name_Implies_Lvalue_Prefix (Attribute_Name (P));
7641
7642          --  For an expanded name, the name is an lvalue if the expanded name
7643          --  is an lvalue, but the prefix is never an lvalue, since it is just
7644          --  the scope where the name is found.
7645
7646          when N_Expanded_Name        =>
7647             if N = Prefix (P) then
7648                return May_Be_Lvalue (P);
7649             else
7650                return False;
7651             end if;
7652
7653          --  For a selected component A.B, A is certainly an lvalue if A.B is.
7654          --  B is a little interesting, if we have A.B := 3, there is some
7655          --  discussion as to whether B is an lvalue or not, we choose to say
7656          --  it is. Note however that A is not an lvalue if it is of an access
7657          --  type since this is an implicit dereference.
7658
7659          when N_Selected_Component   =>
7660             if N = Prefix (P)
7661               and then Present (Etype (N))
7662               and then Is_Access_Type (Etype (N))
7663             then
7664                return False;
7665             else
7666                return May_Be_Lvalue (P);
7667             end if;
7668
7669          --  For an indexed component or slice, the index or slice bounds is
7670          --  never an lvalue. The prefix is an lvalue if the indexed component
7671          --  or slice is an lvalue, except if it is an access type, where we
7672          --  have an implicit dereference.
7673
7674          when N_Indexed_Component    =>
7675             if N /= Prefix (P)
7676               or else (Present (Etype (N)) and then Is_Access_Type (Etype (N)))
7677             then
7678                return False;
7679             else
7680                return May_Be_Lvalue (P);
7681             end if;
7682
7683          --  Prefix of a reference is an lvalue if the reference is an lvalue
7684
7685          when N_Reference            =>
7686             return May_Be_Lvalue (P);
7687
7688          --  Prefix of explicit dereference is never an lvalue
7689
7690          when N_Explicit_Dereference =>
7691             return False;
7692
7693          --  Function call arguments are never lvalues
7694
7695          when N_Function_Call =>
7696             return False;
7697
7698          --  Positional parameter for procedure, entry,  or accept call
7699
7700          when N_Procedure_Call_Statement |
7701               N_Entry_Call_Statement     |
7702               N_Accept_Statement
7703          =>
7704             declare
7705                Proc : Entity_Id;
7706                Form : Entity_Id;
7707                Act  : Node_Id;
7708
7709             begin
7710                Proc := Get_Subprogram_Entity (P);
7711
7712                if No (Proc) then
7713                   return True;
7714                end if;
7715
7716                --  If we are not a list member, something is strange, so
7717                --  be conservative and return True.
7718
7719                if not Is_List_Member (N) then
7720                   return True;
7721                end if;
7722
7723                --  We are going to find the right formal by stepping forward
7724                --  through the formals, as we step backwards in the actuals.
7725
7726                Form := First_Formal (Proc);
7727                Act  := N;
7728                loop
7729                   --  If no formal, something is weird, so be conservative
7730                   --  and return True.
7731
7732                   if No (Form) then
7733                      return True;
7734                   end if;
7735
7736                   Prev (Act);
7737                   exit when No (Act);
7738                   Next_Formal (Form);
7739                end loop;
7740
7741                return Ekind (Form) /= E_In_Parameter;
7742             end;
7743
7744          --  Named parameter for procedure or accept call
7745
7746          when N_Parameter_Association =>
7747             declare
7748                Proc : Entity_Id;
7749                Form : Entity_Id;
7750
7751             begin
7752                Proc := Get_Subprogram_Entity (Parent (P));
7753
7754                if No (Proc) then
7755                   return True;
7756                end if;
7757
7758                --  Loop through formals to find the one that matches
7759
7760                Form := First_Formal (Proc);
7761                loop
7762                   --  If no matching formal, that's peculiar, some kind of
7763                   --  previous error, so return True to be conservative.
7764
7765                   if No (Form) then
7766                      return True;
7767                   end if;
7768
7769                   --  Else test for match
7770
7771                   if Chars (Form) = Chars (Selector_Name (P)) then
7772                      return Ekind (Form) /= E_In_Parameter;
7773                   end if;
7774
7775                   Next_Formal (Form);
7776                end loop;
7777             end;
7778
7779          --  Test for appearing in a conversion that itself appears in an
7780          --  lvalue context, since this should be an lvalue.
7781
7782          when N_Type_Conversion =>
7783             return May_Be_Lvalue (P);
7784
7785          --  Test for appearance in object renaming declaration
7786
7787          when N_Object_Renaming_Declaration =>
7788             return True;
7789
7790          --  All other references are definitely not lvalues
7791
7792          when others =>
7793             return False;
7794
7795       end case;
7796    end May_Be_Lvalue;
7797
7798    -----------------------
7799    -- Mark_Coextensions --
7800    -----------------------
7801
7802    procedure Mark_Coextensions (Context_Nod : Node_Id; Root_Nod : Node_Id) is
7803       Is_Dynamic : Boolean;
7804       --  Indicates whether the context causes nested coextensions to be
7805       --  dynamic or static
7806
7807       function Mark_Allocator (N : Node_Id) return Traverse_Result;
7808       --  Recognize an allocator node and label it as a dynamic coextension
7809
7810       --------------------
7811       -- Mark_Allocator --
7812       --------------------
7813
7814       function Mark_Allocator (N : Node_Id) return Traverse_Result is
7815       begin
7816          if Nkind (N) = N_Allocator then
7817             if Is_Dynamic then
7818                Set_Is_Dynamic_Coextension (N);
7819             else
7820                Set_Is_Static_Coextension (N);
7821             end if;
7822          end if;
7823
7824          return OK;
7825       end Mark_Allocator;
7826
7827       procedure Mark_Allocators is new Traverse_Proc (Mark_Allocator);
7828
7829    --  Start of processing Mark_Coextensions
7830
7831    begin
7832       case Nkind (Context_Nod) is
7833          when N_Assignment_Statement    |
7834               N_Simple_Return_Statement =>
7835             Is_Dynamic := Nkind (Expression (Context_Nod)) = N_Allocator;
7836
7837          when N_Object_Declaration =>
7838             Is_Dynamic := Nkind (Root_Nod) = N_Allocator;
7839
7840          --  This routine should not be called for constructs which may not
7841          --  contain coextensions.
7842
7843          when others =>
7844             raise Program_Error;
7845       end case;
7846
7847       Mark_Allocators (Root_Nod);
7848    end Mark_Coextensions;
7849
7850    ----------------------
7851    -- Needs_One_Actual --
7852    ----------------------
7853
7854    function Needs_One_Actual (E : Entity_Id) return Boolean is
7855       Formal : Entity_Id;
7856
7857    begin
7858       if Ada_Version >= Ada_05
7859         and then Present (First_Formal (E))
7860       then
7861          Formal := Next_Formal (First_Formal (E));
7862          while Present (Formal) loop
7863             if No (Default_Value (Formal)) then
7864                return False;
7865             end if;
7866
7867             Next_Formal (Formal);
7868          end loop;
7869
7870          return True;
7871
7872       else
7873          return False;
7874       end if;
7875    end Needs_One_Actual;
7876
7877    ------------------------
7878    -- New_Copy_List_Tree --
7879    ------------------------
7880
7881    function New_Copy_List_Tree (List : List_Id) return List_Id is
7882       NL : List_Id;
7883       E  : Node_Id;
7884
7885    begin
7886       if List = No_List then
7887          return No_List;
7888
7889       else
7890          NL := New_List;
7891          E := First (List);
7892
7893          while Present (E) loop
7894             Append (New_Copy_Tree (E), NL);
7895             E := Next (E);
7896          end loop;
7897
7898          return NL;
7899       end if;
7900    end New_Copy_List_Tree;
7901
7902    -------------------
7903    -- New_Copy_Tree --
7904    -------------------
7905
7906    use Atree.Unchecked_Access;
7907    use Atree_Private_Part;
7908
7909    --  Our approach here requires a two pass traversal of the tree. The
7910    --  first pass visits all nodes that eventually will be copied looking
7911    --  for defining Itypes. If any defining Itypes are found, then they are
7912    --  copied, and an entry is added to the replacement map. In the second
7913    --  phase, the tree is copied, using the replacement map to replace any
7914    --  Itype references within the copied tree.
7915
7916    --  The following hash tables are used if the Map supplied has more
7917    --  than hash threshhold entries to speed up access to the map. If
7918    --  there are fewer entries, then the map is searched sequentially
7919    --  (because setting up a hash table for only a few entries takes
7920    --  more time than it saves.
7921
7922    function New_Copy_Hash (E : Entity_Id) return NCT_Header_Num;
7923    --  Hash function used for hash operations
7924
7925    -------------------
7926    -- New_Copy_Hash --
7927    -------------------
7928
7929    function New_Copy_Hash (E : Entity_Id) return NCT_Header_Num is
7930    begin
7931       return Nat (E) mod (NCT_Header_Num'Last + 1);
7932    end New_Copy_Hash;
7933
7934    ---------------
7935    -- NCT_Assoc --
7936    ---------------
7937
7938    --  The hash table NCT_Assoc associates old entities in the table
7939    --  with their corresponding new entities (i.e. the pairs of entries
7940    --  presented in the original Map argument are Key-Element pairs).
7941
7942    package NCT_Assoc is new Simple_HTable (
7943      Header_Num => NCT_Header_Num,
7944      Element    => Entity_Id,
7945      No_Element => Empty,
7946      Key        => Entity_Id,
7947      Hash       => New_Copy_Hash,
7948      Equal      => Types."=");
7949
7950    ---------------------
7951    -- NCT_Itype_Assoc --
7952    ---------------------
7953
7954    --  The hash table NCT_Itype_Assoc contains entries only for those
7955    --  old nodes which have a non-empty Associated_Node_For_Itype set.
7956    --  The key is the associated node, and the element is the new node
7957    --  itself (NOT the associated node for the new node).
7958
7959    package NCT_Itype_Assoc is new Simple_HTable (
7960      Header_Num => NCT_Header_Num,
7961      Element    => Entity_Id,
7962      No_Element => Empty,
7963      Key        => Entity_Id,
7964      Hash       => New_Copy_Hash,
7965      Equal      => Types."=");
7966
7967    --  Start of processing for New_Copy_Tree function
7968
7969    function New_Copy_Tree
7970      (Source    : Node_Id;
7971       Map       : Elist_Id := No_Elist;
7972       New_Sloc  : Source_Ptr := No_Location;
7973       New_Scope : Entity_Id := Empty) return Node_Id
7974    is
7975       Actual_Map : Elist_Id := Map;
7976       --  This is the actual map for the copy. It is initialized with the
7977       --  given elements, and then enlarged as required for Itypes that are
7978       --  copied during the first phase of the copy operation. The visit
7979       --  procedures add elements to this map as Itypes are encountered.
7980       --  The reason we cannot use Map directly, is that it may well be
7981       --  (and normally is) initialized to No_Elist, and if we have mapped
7982       --  entities, we have to reset it to point to a real Elist.
7983
7984       function Assoc (N : Node_Or_Entity_Id) return Node_Id;
7985       --  Called during second phase to map entities into their corresponding
7986       --  copies using Actual_Map. If the argument is not an entity, or is not
7987       --  in Actual_Map, then it is returned unchanged.
7988
7989       procedure Build_NCT_Hash_Tables;
7990       --  Builds hash tables (number of elements >= threshold value)
7991
7992       function Copy_Elist_With_Replacement
7993         (Old_Elist : Elist_Id) return Elist_Id;
7994       --  Called during second phase to copy element list doing replacements
7995
7996       procedure Copy_Itype_With_Replacement (New_Itype : Entity_Id);
7997       --  Called during the second phase to process a copied Itype. The actual
7998       --  copy happened during the first phase (so that we could make the entry
7999       --  in the mapping), but we still have to deal with the descendents of
8000       --  the copied Itype and copy them where necessary.
8001
8002       function Copy_List_With_Replacement (Old_List : List_Id) return List_Id;
8003       --  Called during second phase to copy list doing replacements
8004
8005       function Copy_Node_With_Replacement (Old_Node : Node_Id) return Node_Id;
8006       --  Called during second phase to copy node doing replacements
8007
8008       procedure Visit_Elist (E : Elist_Id);
8009       --  Called during first phase to visit all elements of an Elist
8010
8011       procedure Visit_Field (F : Union_Id; N : Node_Id);
8012       --  Visit a single field, recursing to call Visit_Node or Visit_List
8013       --  if the field is a syntactic descendent of the current node (i.e.
8014       --  its parent is Node N).
8015
8016       procedure Visit_Itype (Old_Itype : Entity_Id);
8017       --  Called during first phase to visit subsidiary fields of a defining
8018       --  Itype, and also create a copy and make an entry in the replacement
8019       --  map for the new copy.
8020
8021       procedure Visit_List (L : List_Id);
8022       --  Called during first phase to visit all elements of a List
8023
8024       procedure Visit_Node (N : Node_Or_Entity_Id);
8025       --  Called during first phase to visit a node and all its subtrees
8026
8027       -----------
8028       -- Assoc --
8029       -----------
8030
8031       function Assoc (N : Node_Or_Entity_Id) return Node_Id is
8032          E   : Elmt_Id;
8033          Ent : Entity_Id;
8034
8035       begin
8036          if not Has_Extension (N) or else No (Actual_Map) then
8037             return N;
8038
8039          elsif NCT_Hash_Tables_Used then
8040             Ent := NCT_Assoc.Get (Entity_Id (N));
8041
8042             if Present (Ent) then
8043                return Ent;
8044             else
8045                return N;
8046             end if;
8047
8048          --  No hash table used, do serial search
8049
8050          else
8051             E := First_Elmt (Actual_Map);
8052             while Present (E) loop
8053                if Node (E) = N then
8054                   return Node (Next_Elmt (E));
8055                else
8056                   E := Next_Elmt (Next_Elmt (E));
8057                end if;
8058             end loop;
8059          end if;
8060
8061          return N;
8062       end Assoc;
8063
8064       ---------------------------
8065       -- Build_NCT_Hash_Tables --
8066       ---------------------------
8067
8068       procedure Build_NCT_Hash_Tables is
8069          Elmt : Elmt_Id;
8070          Ent  : Entity_Id;
8071       begin
8072          if NCT_Hash_Table_Setup then
8073             NCT_Assoc.Reset;
8074             NCT_Itype_Assoc.Reset;
8075          end if;
8076
8077          Elmt := First_Elmt (Actual_Map);
8078          while Present (Elmt) loop
8079             Ent := Node (Elmt);
8080
8081             --  Get new entity, and associate old and new
8082
8083             Next_Elmt (Elmt);
8084             NCT_Assoc.Set (Ent, Node (Elmt));
8085
8086             if Is_Type (Ent) then
8087                declare
8088                   Anode : constant Entity_Id :=
8089                             Associated_Node_For_Itype (Ent);
8090
8091                begin
8092                   if Present (Anode) then
8093
8094                      --  Enter a link between the associated node of the
8095                      --  old Itype and the new Itype, for updating later
8096                      --  when node is copied.
8097
8098                      NCT_Itype_Assoc.Set (Anode, Node (Elmt));
8099                   end if;
8100                end;
8101             end if;
8102
8103             Next_Elmt (Elmt);
8104          end loop;
8105
8106          NCT_Hash_Tables_Used := True;
8107          NCT_Hash_Table_Setup := True;
8108       end Build_NCT_Hash_Tables;
8109
8110       ---------------------------------
8111       -- Copy_Elist_With_Replacement --
8112       ---------------------------------
8113
8114       function Copy_Elist_With_Replacement
8115         (Old_Elist : Elist_Id) return Elist_Id
8116       is
8117          M         : Elmt_Id;
8118          New_Elist : Elist_Id;
8119
8120       begin
8121          if No (Old_Elist) then
8122             return No_Elist;
8123
8124          else
8125             New_Elist := New_Elmt_List;
8126
8127             M := First_Elmt (Old_Elist);
8128             while Present (M) loop
8129                Append_Elmt (Copy_Node_With_Replacement (Node (M)), New_Elist);
8130                Next_Elmt (M);
8131             end loop;
8132          end if;
8133
8134          return New_Elist;
8135       end Copy_Elist_With_Replacement;
8136
8137       ---------------------------------
8138       -- Copy_Itype_With_Replacement --
8139       ---------------------------------
8140
8141       --  This routine exactly parallels its phase one analog Visit_Itype,
8142
8143       procedure Copy_Itype_With_Replacement (New_Itype : Entity_Id) is
8144       begin
8145          --  Translate Next_Entity, Scope and Etype fields, in case they
8146          --  reference entities that have been mapped into copies.
8147
8148          Set_Next_Entity (New_Itype, Assoc (Next_Entity (New_Itype)));
8149          Set_Etype       (New_Itype, Assoc (Etype       (New_Itype)));
8150
8151          if Present (New_Scope) then
8152             Set_Scope    (New_Itype, New_Scope);
8153          else
8154             Set_Scope    (New_Itype, Assoc (Scope       (New_Itype)));
8155          end if;
8156
8157          --  Copy referenced fields
8158
8159          if Is_Discrete_Type (New_Itype) then
8160             Set_Scalar_Range (New_Itype,
8161               Copy_Node_With_Replacement (Scalar_Range (New_Itype)));
8162
8163          elsif Has_Discriminants (Base_Type (New_Itype)) then
8164             Set_Discriminant_Constraint (New_Itype,
8165               Copy_Elist_With_Replacement
8166                 (Discriminant_Constraint (New_Itype)));
8167
8168          elsif Is_Array_Type (New_Itype) then
8169             if Present (First_Index (New_Itype)) then
8170                Set_First_Index (New_Itype,
8171                  First (Copy_List_With_Replacement
8172                          (List_Containing (First_Index (New_Itype)))));
8173             end if;
8174
8175             if Is_Packed (New_Itype) then
8176                Set_Packed_Array_Type (New_Itype,
8177                  Copy_Node_With_Replacement
8178                    (Packed_Array_Type (New_Itype)));
8179             end if;
8180          end if;
8181       end Copy_Itype_With_Replacement;
8182
8183       --------------------------------
8184       -- Copy_List_With_Replacement --
8185       --------------------------------
8186
8187       function Copy_List_With_Replacement
8188         (Old_List : List_Id) return List_Id
8189       is
8190          New_List : List_Id;
8191          E        : Node_Id;
8192
8193       begin
8194          if Old_List = No_List then
8195             return No_List;
8196
8197          else
8198             New_List := Empty_List;
8199
8200             E := First (Old_List);
8201             while Present (E) loop
8202                Append (Copy_Node_With_Replacement (E), New_List);
8203                Next (E);
8204             end loop;
8205
8206             return New_List;
8207          end if;
8208       end Copy_List_With_Replacement;
8209
8210       --------------------------------
8211       -- Copy_Node_With_Replacement --
8212       --------------------------------
8213
8214       function Copy_Node_With_Replacement
8215         (Old_Node : Node_Id) return Node_Id
8216       is
8217          New_Node : Node_Id;
8218
8219          procedure Adjust_Named_Associations
8220            (Old_Node : Node_Id;
8221             New_Node : Node_Id);
8222          --  If a call node has named associations, these are chained through
8223          --  the First_Named_Actual, Next_Named_Actual links. These must be
8224          --  propagated separately to the new parameter list, because these
8225          --  are not syntactic fields.
8226
8227          function Copy_Field_With_Replacement
8228            (Field : Union_Id) return Union_Id;
8229          --  Given Field, which is a field of Old_Node, return a copy of it
8230          --  if it is a syntactic field (i.e. its parent is Node), setting
8231          --  the parent of the copy to poit to New_Node. Otherwise returns
8232          --  the field (possibly mapped if it is an entity).
8233
8234          -------------------------------
8235          -- Adjust_Named_Associations --
8236          -------------------------------
8237
8238          procedure Adjust_Named_Associations
8239            (Old_Node : Node_Id;
8240             New_Node : Node_Id)
8241          is
8242             Old_E : Node_Id;
8243             New_E : Node_Id;
8244
8245             Old_Next : Node_Id;
8246             New_Next : Node_Id;
8247
8248          begin
8249             Old_E := First (Parameter_Associations (Old_Node));
8250             New_E := First (Parameter_Associations (New_Node));
8251             while Present (Old_E) loop
8252                if Nkind (Old_E) = N_Parameter_Association
8253                  and then Present (Next_Named_Actual (Old_E))
8254                then
8255                   if First_Named_Actual (Old_Node)
8256                     =  Explicit_Actual_Parameter (Old_E)
8257                   then
8258                      Set_First_Named_Actual
8259                        (New_Node, Explicit_Actual_Parameter (New_E));
8260                   end if;
8261
8262                   --  Now scan parameter list from the beginning,to locate
8263                   --  next named actual, which can be out of order.
8264
8265                   Old_Next := First (Parameter_Associations (Old_Node));
8266                   New_Next := First (Parameter_Associations (New_Node));
8267
8268                   while Nkind (Old_Next) /= N_Parameter_Association
8269                     or else  Explicit_Actual_Parameter (Old_Next)
8270                       /= Next_Named_Actual (Old_E)
8271                   loop
8272                      Next (Old_Next);
8273                      Next (New_Next);
8274                   end loop;
8275
8276                   Set_Next_Named_Actual
8277                     (New_E, Explicit_Actual_Parameter (New_Next));
8278                end if;
8279
8280                Next (Old_E);
8281                Next (New_E);
8282             end loop;
8283          end Adjust_Named_Associations;
8284
8285          ---------------------------------
8286          -- Copy_Field_With_Replacement --
8287          ---------------------------------
8288
8289          function Copy_Field_With_Replacement
8290            (Field : Union_Id) return Union_Id
8291          is
8292          begin
8293             if Field = Union_Id (Empty) then
8294                return Field;
8295
8296             elsif Field in Node_Range then
8297                declare
8298                   Old_N : constant Node_Id := Node_Id (Field);
8299                   New_N : Node_Id;
8300
8301                begin
8302                   --  If syntactic field, as indicated by the parent pointer
8303                   --  being set, then copy the referenced node recursively.
8304
8305                   if Parent (Old_N) = Old_Node then
8306                      New_N := Copy_Node_With_Replacement (Old_N);
8307
8308                      if New_N /= Old_N then
8309                         Set_Parent (New_N, New_Node);
8310                      end if;
8311
8312                   --  For semantic fields, update possible entity reference
8313                   --  from the replacement map.
8314
8315                   else
8316                      New_N := Assoc (Old_N);
8317                   end if;
8318
8319                   return Union_Id (New_N);
8320                end;
8321
8322             elsif Field in List_Range then
8323                declare
8324                   Old_L : constant List_Id := List_Id (Field);
8325                   New_L : List_Id;
8326
8327                begin
8328                   --  If syntactic field, as indicated by the parent pointer,
8329                   --  then recursively copy the entire referenced list.
8330
8331                   if Parent (Old_L) = Old_Node then
8332                      New_L := Copy_List_With_Replacement (Old_L);
8333                      Set_Parent (New_L, New_Node);
8334
8335                   --  For semantic list, just returned unchanged
8336
8337                   else
8338                      New_L := Old_L;
8339                   end if;
8340
8341                   return Union_Id (New_L);
8342                end;
8343
8344             --  Anything other than a list or a node is returned unchanged
8345
8346             else
8347                return Field;
8348             end if;
8349          end Copy_Field_With_Replacement;
8350
8351       --  Start of processing for Copy_Node_With_Replacement
8352
8353       begin
8354          if Old_Node <= Empty_Or_Error then
8355             return Old_Node;
8356
8357          elsif Has_Extension (Old_Node) then
8358             return Assoc (Old_Node);
8359
8360          else
8361             New_Node := New_Copy (Old_Node);
8362
8363             --  If the node we are copying is the associated node of a
8364             --  previously copied Itype, then adjust the associated node
8365             --  of the copy of that Itype accordingly.
8366
8367             if Present (Actual_Map) then
8368                declare
8369                   E   : Elmt_Id;
8370                   Ent : Entity_Id;
8371
8372                begin
8373                   --  Case of hash table used
8374
8375                   if NCT_Hash_Tables_Used then
8376                      Ent := NCT_Itype_Assoc.Get (Old_Node);
8377
8378                      if Present (Ent) then
8379                         Set_Associated_Node_For_Itype (Ent, New_Node);
8380                      end if;
8381
8382                   --  Case of no hash table used
8383
8384                   else
8385                      E := First_Elmt (Actual_Map);
8386                      while Present (E) loop
8387                         if Is_Itype (Node (E))
8388                           and then
8389                             Old_Node = Associated_Node_For_Itype (Node (E))
8390                         then
8391                            Set_Associated_Node_For_Itype
8392                              (Node (Next_Elmt (E)), New_Node);
8393                         end if;
8394
8395                         E := Next_Elmt (Next_Elmt (E));
8396                      end loop;
8397                   end if;
8398                end;
8399             end if;
8400
8401             --  Recursively copy descendents
8402
8403             Set_Field1
8404               (New_Node, Copy_Field_With_Replacement (Field1 (New_Node)));
8405             Set_Field2
8406               (New_Node, Copy_Field_With_Replacement (Field2 (New_Node)));
8407             Set_Field3
8408               (New_Node, Copy_Field_With_Replacement (Field3 (New_Node)));
8409             Set_Field4
8410               (New_Node, Copy_Field_With_Replacement (Field4 (New_Node)));
8411             Set_Field5
8412               (New_Node, Copy_Field_With_Replacement (Field5 (New_Node)));
8413
8414             --  Adjust Sloc of new node if necessary
8415
8416             if New_Sloc /= No_Location then
8417                Set_Sloc (New_Node, New_Sloc);
8418
8419                --  If we adjust the Sloc, then we are essentially making
8420                --  a completely new node, so the Comes_From_Source flag
8421                --  should be reset to the proper default value.
8422
8423                Nodes.Table (New_Node).Comes_From_Source :=
8424                  Default_Node.Comes_From_Source;
8425             end if;
8426
8427             --  If the node is call and has named associations,
8428             --  set the corresponding links in the copy.
8429
8430             if (Nkind (Old_Node) = N_Function_Call
8431                  or else Nkind (Old_Node) = N_Entry_Call_Statement
8432                  or else
8433                    Nkind (Old_Node) = N_Procedure_Call_Statement)
8434               and then Present (First_Named_Actual (Old_Node))
8435             then
8436                Adjust_Named_Associations (Old_Node, New_Node);
8437             end if;
8438
8439             --  Reset First_Real_Statement for Handled_Sequence_Of_Statements.
8440             --  The replacement mechanism applies to entities, and is not used
8441             --  here. Eventually we may need a more general graph-copying
8442             --  routine. For now, do a sequential search to find desired node.
8443
8444             if Nkind (Old_Node) = N_Handled_Sequence_Of_Statements
8445               and then Present (First_Real_Statement (Old_Node))
8446             then
8447                declare
8448                   Old_F  : constant Node_Id := First_Real_Statement (Old_Node);
8449                   N1, N2 : Node_Id;
8450
8451                begin
8452                   N1 := First (Statements (Old_Node));
8453                   N2 := First (Statements (New_Node));
8454
8455                   while N1 /= Old_F loop
8456                      Next (N1);
8457                      Next (N2);
8458                   end loop;
8459
8460                   Set_First_Real_Statement (New_Node, N2);
8461                end;
8462             end if;
8463          end if;
8464
8465          --  All done, return copied node
8466
8467          return New_Node;
8468       end Copy_Node_With_Replacement;
8469
8470       -----------------
8471       -- Visit_Elist --
8472       -----------------
8473
8474       procedure Visit_Elist (E : Elist_Id) is
8475          Elmt : Elmt_Id;
8476       begin
8477          if Present (E) then
8478             Elmt := First_Elmt (E);
8479
8480             while Elmt /= No_Elmt loop
8481                Visit_Node (Node (Elmt));
8482                Next_Elmt (Elmt);
8483             end loop;
8484          end if;
8485       end Visit_Elist;
8486
8487       -----------------
8488       -- Visit_Field --
8489       -----------------
8490
8491       procedure Visit_Field (F : Union_Id; N : Node_Id) is
8492       begin
8493          if F = Union_Id (Empty) then
8494             return;
8495
8496          elsif F in Node_Range then
8497
8498             --  Copy node if it is syntactic, i.e. its parent pointer is
8499             --  set to point to the field that referenced it (certain
8500             --  Itypes will also meet this criterion, which is fine, since
8501             --  these are clearly Itypes that do need to be copied, since
8502             --  we are copying their parent.)
8503
8504             if Parent (Node_Id (F)) = N then
8505                Visit_Node (Node_Id (F));
8506                return;
8507
8508             --  Another case, if we are pointing to an Itype, then we want
8509             --  to copy it if its associated node is somewhere in the tree
8510             --  being copied.
8511
8512             --  Note: the exclusion of self-referential copies is just an
8513             --  optimization, since the search of the already copied list
8514             --  would catch it, but it is a common case (Etype pointing
8515             --  to itself for an Itype that is a base type).
8516
8517             elsif Has_Extension (Node_Id (F))
8518               and then Is_Itype (Entity_Id (F))
8519               and then Node_Id (F) /= N
8520             then
8521                declare
8522                   P : Node_Id;
8523
8524                begin
8525                   P := Associated_Node_For_Itype (Node_Id (F));
8526                   while Present (P) loop
8527                      if P = Source then
8528                         Visit_Node (Node_Id (F));
8529                         return;
8530                      else
8531                         P := Parent (P);
8532                      end if;
8533                   end loop;
8534
8535                   --  An Itype whose parent is not being copied definitely
8536                   --  should NOT be copied, since it does not belong in any
8537                   --  sense to the copied subtree.
8538
8539                   return;
8540                end;
8541             end if;
8542
8543          elsif F in List_Range
8544            and then Parent (List_Id (F)) = N
8545          then
8546             Visit_List (List_Id (F));
8547             return;
8548          end if;
8549       end Visit_Field;
8550
8551       -----------------
8552       -- Visit_Itype --
8553       -----------------
8554
8555       procedure Visit_Itype (Old_Itype : Entity_Id) is
8556          New_Itype : Entity_Id;
8557          E         : Elmt_Id;
8558          Ent       : Entity_Id;
8559
8560       begin
8561          --  Itypes that describe the designated type of access to subprograms
8562          --  have the structure of subprogram declarations, with signatures,
8563          --  etc. Either we duplicate the signatures completely, or choose to
8564          --  share such itypes, which is fine because their elaboration will
8565          --  have no side effects.
8566
8567          if Ekind (Old_Itype) = E_Subprogram_Type then
8568             return;
8569          end if;
8570
8571          New_Itype := New_Copy (Old_Itype);
8572
8573          --  The new Itype has all the attributes of the old one, and
8574          --  we just copy the contents of the entity. However, the back-end
8575          --  needs different names for debugging purposes, so we create a
8576          --  new internal name for it in all cases.
8577
8578          Set_Chars (New_Itype, New_Internal_Name ('T'));
8579
8580          --  If our associated node is an entity that has already been copied,
8581          --  then set the associated node of the copy to point to the right
8582          --  copy. If we have copied an Itype that is itself the associated
8583          --  node of some previously copied Itype, then we set the right
8584          --  pointer in the other direction.
8585
8586          if Present (Actual_Map) then
8587
8588             --  Case of hash tables used
8589
8590             if NCT_Hash_Tables_Used then
8591
8592                Ent := NCT_Assoc.Get (Associated_Node_For_Itype (Old_Itype));
8593
8594                if Present (Ent) then
8595                   Set_Associated_Node_For_Itype (New_Itype, Ent);
8596                end if;
8597
8598                Ent := NCT_Itype_Assoc.Get (Old_Itype);
8599                if Present (Ent) then
8600                   Set_Associated_Node_For_Itype (Ent, New_Itype);
8601
8602                --  If the hash table has no association for this Itype and
8603                --  its associated node, enter one now.
8604
8605                else
8606                   NCT_Itype_Assoc.Set
8607                     (Associated_Node_For_Itype (Old_Itype), New_Itype);
8608                end if;
8609
8610             --  Case of hash tables not used
8611
8612             else
8613                E := First_Elmt (Actual_Map);
8614                while Present (E) loop
8615                   if Associated_Node_For_Itype (Old_Itype) = Node (E) then
8616                      Set_Associated_Node_For_Itype
8617                        (New_Itype, Node (Next_Elmt (E)));
8618                   end if;
8619
8620                   if Is_Type (Node (E))
8621                     and then
8622                       Old_Itype = Associated_Node_For_Itype (Node (E))
8623                   then
8624                      Set_Associated_Node_For_Itype
8625                        (Node (Next_Elmt (E)), New_Itype);
8626                   end if;
8627
8628                   E := Next_Elmt (Next_Elmt (E));
8629                end loop;
8630             end if;
8631          end if;
8632
8633          if Present (Freeze_Node (New_Itype)) then
8634             Set_Is_Frozen (New_Itype, False);
8635             Set_Freeze_Node (New_Itype, Empty);
8636          end if;
8637
8638          --  Add new association to map
8639
8640          if No (Actual_Map) then
8641             Actual_Map := New_Elmt_List;
8642          end if;
8643
8644          Append_Elmt (Old_Itype, Actual_Map);
8645          Append_Elmt (New_Itype, Actual_Map);
8646
8647          if NCT_Hash_Tables_Used then
8648             NCT_Assoc.Set (Old_Itype, New_Itype);
8649
8650          else
8651             NCT_Table_Entries := NCT_Table_Entries + 1;
8652
8653             if NCT_Table_Entries > NCT_Hash_Threshhold then
8654                Build_NCT_Hash_Tables;
8655             end if;
8656          end if;
8657
8658          --  If a record subtype is simply copied, the entity list will be
8659          --  shared. Thus cloned_Subtype must be set to indicate the sharing.
8660
8661          if Ekind (Old_Itype) = E_Record_Subtype
8662            or else Ekind (Old_Itype) = E_Class_Wide_Subtype
8663          then
8664             Set_Cloned_Subtype (New_Itype, Old_Itype);
8665          end if;
8666
8667          --  Visit descendents that eventually get copied
8668
8669          Visit_Field (Union_Id (Etype (Old_Itype)), Old_Itype);
8670
8671          if Is_Discrete_Type (Old_Itype) then
8672             Visit_Field (Union_Id (Scalar_Range (Old_Itype)), Old_Itype);
8673
8674          elsif Has_Discriminants (Base_Type (Old_Itype)) then
8675             --  ??? This should involve call to Visit_Field
8676             Visit_Elist (Discriminant_Constraint (Old_Itype));
8677
8678          elsif Is_Array_Type (Old_Itype) then
8679             if Present (First_Index (Old_Itype)) then
8680                Visit_Field (Union_Id (List_Containing
8681                                 (First_Index (Old_Itype))),
8682                             Old_Itype);
8683             end if;
8684
8685             if Is_Packed (Old_Itype) then
8686                Visit_Field (Union_Id (Packed_Array_Type (Old_Itype)),
8687                             Old_Itype);
8688             end if;
8689          end if;
8690       end Visit_Itype;
8691
8692       ----------------
8693       -- Visit_List --
8694       ----------------
8695
8696       procedure Visit_List (L : List_Id) is
8697          N : Node_Id;
8698       begin
8699          if L /= No_List then
8700             N := First (L);
8701
8702             while Present (N) loop
8703                Visit_Node (N);
8704                Next (N);
8705             end loop;
8706          end if;
8707       end Visit_List;
8708
8709       ----------------
8710       -- Visit_Node --
8711       ----------------
8712
8713       procedure Visit_Node (N : Node_Or_Entity_Id) is
8714
8715       --  Start of processing for Visit_Node
8716
8717       begin
8718          --  Handle case of an Itype, which must be copied
8719
8720          if Has_Extension (N)
8721            and then Is_Itype (N)
8722          then
8723             --  Nothing to do if already in the list. This can happen with an
8724             --  Itype entity that appears more than once in the tree.
8725             --  Note that we do not want to visit descendents in this case.
8726
8727             --  Test for already in list when hash table is used
8728
8729             if NCT_Hash_Tables_Used then
8730                if Present (NCT_Assoc.Get (Entity_Id (N))) then
8731                   return;
8732                end if;
8733
8734             --  Test for already in list when hash table not used
8735
8736             else
8737                declare
8738                   E : Elmt_Id;
8739                begin
8740                   if Present (Actual_Map) then
8741                      E := First_Elmt (Actual_Map);
8742                      while Present (E) loop
8743                         if Node (E) = N then
8744                            return;
8745                         else
8746                            E := Next_Elmt (Next_Elmt (E));
8747                         end if;
8748                      end loop;
8749                   end if;
8750                end;
8751             end if;
8752
8753             Visit_Itype (N);
8754          end if;
8755
8756          --  Visit descendents
8757
8758          Visit_Field (Field1 (N), N);
8759          Visit_Field (Field2 (N), N);
8760          Visit_Field (Field3 (N), N);
8761          Visit_Field (Field4 (N), N);
8762          Visit_Field (Field5 (N), N);
8763       end Visit_Node;
8764
8765    --  Start of processing for New_Copy_Tree
8766
8767    begin
8768       Actual_Map := Map;
8769
8770       --  See if we should use hash table
8771
8772       if No (Actual_Map) then
8773          NCT_Hash_Tables_Used := False;
8774
8775       else
8776          declare
8777             Elmt : Elmt_Id;
8778
8779          begin
8780             NCT_Table_Entries := 0;
8781
8782             Elmt := First_Elmt (Actual_Map);
8783             while Present (Elmt) loop
8784                NCT_Table_Entries := NCT_Table_Entries + 1;
8785                Next_Elmt (Elmt);
8786                Next_Elmt (Elmt);
8787             end loop;
8788
8789             if NCT_Table_Entries > NCT_Hash_Threshhold then
8790                Build_NCT_Hash_Tables;
8791             else
8792                NCT_Hash_Tables_Used := False;
8793             end if;
8794          end;
8795       end if;
8796
8797       --  Hash table set up if required, now start phase one by visiting
8798       --  top node (we will recursively visit the descendents).
8799
8800       Visit_Node (Source);
8801
8802       --  Now the second phase of the copy can start. First we process
8803       --  all the mapped entities, copying their descendents.
8804
8805       if Present (Actual_Map) then
8806          declare
8807             Elmt      : Elmt_Id;
8808             New_Itype : Entity_Id;
8809          begin
8810             Elmt := First_Elmt (Actual_Map);
8811             while Present (Elmt) loop
8812                Next_Elmt (Elmt);
8813                New_Itype := Node (Elmt);
8814                Copy_Itype_With_Replacement (New_Itype);
8815                Next_Elmt (Elmt);
8816             end loop;
8817          end;
8818       end if;
8819
8820       --  Now we can copy the actual tree
8821
8822       return Copy_Node_With_Replacement (Source);
8823    end New_Copy_Tree;
8824
8825    -------------------------
8826    -- New_External_Entity --
8827    -------------------------
8828
8829    function New_External_Entity
8830      (Kind         : Entity_Kind;
8831       Scope_Id     : Entity_Id;
8832       Sloc_Value   : Source_Ptr;
8833       Related_Id   : Entity_Id;
8834       Suffix       : Character;
8835       Suffix_Index : Nat := 0;
8836       Prefix       : Character := ' ') return Entity_Id
8837    is
8838       N : constant Entity_Id :=
8839             Make_Defining_Identifier (Sloc_Value,
8840               New_External_Name
8841                 (Chars (Related_Id), Suffix, Suffix_Index, Prefix));
8842
8843    begin
8844       Set_Ekind          (N, Kind);
8845       Set_Is_Internal    (N, True);
8846       Append_Entity      (N, Scope_Id);
8847       Set_Public_Status  (N);
8848
8849       if Kind in Type_Kind then
8850          Init_Size_Align (N);
8851       end if;
8852
8853       return N;
8854    end New_External_Entity;
8855
8856    -------------------------
8857    -- New_Internal_Entity --
8858    -------------------------
8859
8860    function New_Internal_Entity
8861      (Kind       : Entity_Kind;
8862       Scope_Id   : Entity_Id;
8863       Sloc_Value : Source_Ptr;
8864       Id_Char    : Character) return Entity_Id
8865    is
8866       N : constant Entity_Id :=
8867             Make_Defining_Identifier (Sloc_Value, New_Internal_Name (Id_Char));
8868
8869    begin
8870       Set_Ekind          (N, Kind);
8871       Set_Is_Internal    (N, True);
8872       Append_Entity      (N, Scope_Id);
8873
8874       if Kind in Type_Kind then
8875          Init_Size_Align (N);
8876       end if;
8877
8878       return N;
8879    end New_Internal_Entity;
8880
8881    -----------------
8882    -- Next_Actual --
8883    -----------------
8884
8885    function Next_Actual (Actual_Id : Node_Id) return Node_Id is
8886       N  : Node_Id;
8887
8888    begin
8889       --  If we are pointing at a positional parameter, it is a member of a
8890       --  node list (the list of parameters), and the next parameter is the
8891       --  next node on the list, unless we hit a parameter association, then
8892       --  we shift to using the chain whose head is the First_Named_Actual in
8893       --  the parent, and then is threaded using the Next_Named_Actual of the
8894       --  Parameter_Association. All this fiddling is because the original node
8895       --  list is in the textual call order, and what we need is the
8896       --  declaration order.
8897
8898       if Is_List_Member (Actual_Id) then
8899          N := Next (Actual_Id);
8900
8901          if Nkind (N) = N_Parameter_Association then
8902             return First_Named_Actual (Parent (Actual_Id));
8903          else
8904             return N;
8905          end if;
8906
8907       else
8908          return Next_Named_Actual (Parent (Actual_Id));
8909       end if;
8910    end Next_Actual;
8911
8912    procedure Next_Actual (Actual_Id : in out Node_Id) is
8913    begin
8914       Actual_Id := Next_Actual (Actual_Id);
8915    end Next_Actual;
8916
8917    -----------------------
8918    -- Normalize_Actuals --
8919    -----------------------
8920
8921    --  Chain actuals according to formals of subprogram. If there are no named
8922    --  associations, the chain is simply the list of Parameter Associations,
8923    --  since the order is the same as the declaration order. If there are named
8924    --  associations, then the First_Named_Actual field in the N_Function_Call
8925    --  or N_Procedure_Call_Statement node points to the Parameter_Association
8926    --  node for the parameter that comes first in declaration order. The
8927    --  remaining named parameters are then chained in declaration order using
8928    --  Next_Named_Actual.
8929
8930    --  This routine also verifies that the number of actuals is compatible with
8931    --  the number and default values of formals, but performs no type checking
8932    --  (type checking is done by the caller).
8933
8934    --  If the matching succeeds, Success is set to True and the caller proceeds
8935    --  with type-checking. If the match is unsuccessful, then Success is set to
8936    --  False, and the caller attempts a different interpretation, if there is
8937    --  one.
8938
8939    --  If the flag Report is on, the call is not overloaded, and a failure to
8940    --  match can be reported here, rather than in the caller.
8941
8942    procedure Normalize_Actuals
8943      (N       : Node_Id;
8944       S       : Entity_Id;
8945       Report  : Boolean;
8946       Success : out Boolean)
8947    is
8948       Actuals     : constant List_Id := Parameter_Associations (N);
8949       Actual      : Node_Id := Empty;
8950       Formal      : Entity_Id;
8951       Last        : Node_Id := Empty;
8952       First_Named : Node_Id := Empty;
8953       Found       : Boolean;
8954
8955       Formals_To_Match : Integer := 0;
8956       Actuals_To_Match : Integer := 0;
8957
8958       procedure Chain (A : Node_Id);
8959       --  Add named actual at the proper place in the list, using the
8960       --  Next_Named_Actual link.
8961
8962       function Reporting return Boolean;
8963       --  Determines if an error is to be reported. To report an error, we
8964       --  need Report to be True, and also we do not report errors caused
8965       --  by calls to init procs that occur within other init procs. Such
8966       --  errors must always be cascaded errors, since if all the types are
8967       --  declared correctly, the compiler will certainly build decent calls!
8968
8969       -----------
8970       -- Chain --
8971       -----------
8972
8973       procedure Chain (A : Node_Id) is
8974       begin
8975          if No (Last) then
8976
8977             --  Call node points to first actual in list
8978
8979             Set_First_Named_Actual (N, Explicit_Actual_Parameter (A));
8980
8981          else
8982             Set_Next_Named_Actual (Last, Explicit_Actual_Parameter (A));
8983          end if;
8984
8985          Last := A;
8986          Set_Next_Named_Actual (Last, Empty);
8987       end Chain;
8988
8989       ---------------
8990       -- Reporting --
8991       ---------------
8992
8993       function Reporting return Boolean is
8994       begin
8995          if not Report then
8996             return False;
8997
8998          elsif not Within_Init_Proc then
8999             return True;
9000
9001          elsif Is_Init_Proc (Entity (Name (N))) then
9002             return False;
9003
9004          else
9005             return True;
9006          end if;
9007       end Reporting;
9008
9009    --  Start of processing for Normalize_Actuals
9010
9011    begin
9012       if Is_Access_Type (S) then
9013
9014          --  The name in the call is a function call that returns an access
9015          --  to subprogram. The designated type has the list of formals.
9016
9017          Formal := First_Formal (Designated_Type (S));
9018       else
9019          Formal := First_Formal (S);
9020       end if;
9021
9022       while Present (Formal) loop
9023          Formals_To_Match := Formals_To_Match + 1;
9024          Next_Formal (Formal);
9025       end loop;
9026
9027       --  Find if there is a named association, and verify that no positional
9028       --  associations appear after named ones.
9029
9030       if Present (Actuals) then
9031          Actual := First (Actuals);
9032       end if;
9033
9034       while Present (Actual)
9035         and then Nkind (Actual) /= N_Parameter_Association
9036       loop
9037          Actuals_To_Match := Actuals_To_Match + 1;
9038          Next (Actual);
9039       end loop;
9040
9041       if No (Actual) and Actuals_To_Match = Formals_To_Match then
9042
9043          --  Most common case: positional notation, no defaults
9044
9045          Success := True;
9046          return;
9047
9048       elsif Actuals_To_Match > Formals_To_Match then
9049
9050          --  Too many actuals: will not work
9051
9052          if Reporting then
9053             if Is_Entity_Name (Name (N)) then
9054                Error_Msg_N ("too many arguments in call to&", Name (N));
9055             else
9056                Error_Msg_N ("too many arguments in call", N);
9057             end if;
9058          end if;
9059
9060          Success := False;
9061          return;
9062       end if;
9063
9064       First_Named := Actual;
9065
9066       while Present (Actual) loop
9067          if Nkind (Actual) /= N_Parameter_Association then
9068             Error_Msg_N
9069               ("positional parameters not allowed after named ones", Actual);
9070             Success := False;
9071             return;
9072
9073          else
9074             Actuals_To_Match := Actuals_To_Match + 1;
9075          end if;
9076
9077          Next (Actual);
9078       end loop;
9079
9080       if Present (Actuals) then
9081          Actual := First (Actuals);
9082       end if;
9083
9084       Formal := First_Formal (S);
9085       while Present (Formal) loop
9086
9087          --  Match the formals in order. If the corresponding actual is
9088          --  positional, nothing to do. Else scan the list of named actuals
9089          --  to find the one with the right name.
9090
9091          if Present (Actual)
9092            and then Nkind (Actual) /= N_Parameter_Association
9093          then
9094             Next (Actual);
9095             Actuals_To_Match := Actuals_To_Match - 1;
9096             Formals_To_Match := Formals_To_Match - 1;
9097
9098          else
9099             --  For named parameters, search the list of actuals to find
9100             --  one that matches the next formal name.
9101
9102             Actual := First_Named;
9103             Found  := False;
9104             while Present (Actual) loop
9105                if Chars (Selector_Name (Actual)) = Chars (Formal) then
9106                   Found := True;
9107                   Chain (Actual);
9108                   Actuals_To_Match := Actuals_To_Match - 1;
9109                   Formals_To_Match := Formals_To_Match - 1;
9110                   exit;
9111                end if;
9112
9113                Next (Actual);
9114             end loop;
9115
9116             if not Found then
9117                if Ekind (Formal) /= E_In_Parameter
9118                  or else No (Default_Value (Formal))
9119                then
9120                   if Reporting then
9121                      if (Comes_From_Source (S)
9122                           or else Sloc (S) = Standard_Location)
9123                        and then Is_Overloadable (S)
9124                      then
9125                         if No (Actuals)
9126                           and then
9127                            (Nkind (Parent (N)) = N_Procedure_Call_Statement
9128                              or else
9129                            (Nkind (Parent (N)) = N_Function_Call
9130                              or else
9131                             Nkind (Parent (N)) = N_Parameter_Association))
9132                           and then Ekind (S) /= E_Function
9133                         then
9134                            Set_Etype (N, Etype (S));
9135                         else
9136                            Error_Msg_Name_1 := Chars (S);
9137                            Error_Msg_Sloc := Sloc (S);
9138                            Error_Msg_NE
9139                              ("missing argument for parameter & " &
9140                                 "in call to % declared #", N, Formal);
9141                         end if;
9142
9143                      elsif Is_Overloadable (S) then
9144                         Error_Msg_Name_1 := Chars (S);
9145
9146                         --  Point to type derivation that generated the
9147                         --  operation.
9148
9149                         Error_Msg_Sloc := Sloc (Parent (S));
9150
9151                         Error_Msg_NE
9152                           ("missing argument for parameter & " &
9153                              "in call to % (inherited) #", N, Formal);
9154
9155                      else
9156                         Error_Msg_NE
9157                           ("missing argument for parameter &", N, Formal);
9158                      end if;
9159                   end if;
9160
9161                   Success := False;
9162                   return;
9163
9164                else
9165                   Formals_To_Match := Formals_To_Match - 1;
9166                end if;
9167             end if;
9168          end if;
9169
9170          Next_Formal (Formal);
9171       end loop;
9172
9173       if Formals_To_Match = 0 and then Actuals_To_Match = 0 then
9174          Success := True;
9175          return;
9176
9177       else
9178          if Reporting then
9179
9180             --  Find some superfluous named actual that did not get
9181             --  attached to the list of associations.
9182
9183             Actual := First (Actuals);
9184             while Present (Actual) loop
9185                if Nkind (Actual) = N_Parameter_Association
9186                  and then Actual /= Last
9187                  and then No (Next_Named_Actual (Actual))
9188                then
9189                   Error_Msg_N ("unmatched actual & in call",
9190                     Selector_Name (Actual));
9191                   exit;
9192                end if;
9193
9194                Next (Actual);
9195             end loop;
9196          end if;
9197
9198          Success := False;
9199          return;
9200       end if;
9201    end Normalize_Actuals;
9202
9203    --------------------------------
9204    -- Note_Possible_Modification --
9205    --------------------------------
9206
9207    procedure Note_Possible_Modification (N : Node_Id; Sure : Boolean) is
9208       Modification_Comes_From_Source : constant Boolean :=
9209                                          Comes_From_Source (Parent (N));
9210
9211       Ent : Entity_Id;
9212       Exp : Node_Id;
9213
9214    begin
9215       --  Loop to find referenced entity, if there is one
9216
9217       Exp := N;
9218       loop
9219          <<Continue>>
9220          Ent := Empty;
9221
9222          if Is_Entity_Name (Exp) then
9223             Ent := Entity (Exp);
9224
9225             --  If the entity is missing, it is an undeclared identifier,
9226             --  and there is nothing to annotate.
9227
9228             if No (Ent) then
9229                return;
9230             end if;
9231
9232          elsif Nkind (Exp) = N_Explicit_Dereference then
9233             declare
9234                P : constant Node_Id := Prefix (Exp);
9235
9236             begin
9237                if Nkind (P) = N_Selected_Component
9238                  and then Present (
9239                    Entry_Formal (Entity (Selector_Name (P))))
9240                then
9241                   --  Case of a reference to an entry formal
9242
9243                   Ent := Entry_Formal (Entity (Selector_Name (P)));
9244
9245                elsif Nkind (P) = N_Identifier
9246                  and then Nkind (Parent (Entity (P))) = N_Object_Declaration
9247                  and then Present (Expression (Parent (Entity (P))))
9248                  and then Nkind (Expression (Parent (Entity (P))))
9249                    = N_Reference
9250                then
9251                   --  Case of a reference to a value on which side effects have
9252                   --  been removed.
9253
9254                   Exp := Prefix (Expression (Parent (Entity (P))));
9255                   goto Continue;
9256
9257                else
9258                   return;
9259
9260                end if;
9261             end;
9262
9263          elsif     Nkind (Exp) = N_Type_Conversion
9264            or else Nkind (Exp) = N_Unchecked_Type_Conversion
9265          then
9266             Exp := Expression (Exp);
9267             goto Continue;
9268
9269          elsif     Nkind (Exp) = N_Slice
9270            or else Nkind (Exp) = N_Indexed_Component
9271            or else Nkind (Exp) = N_Selected_Component
9272          then
9273             Exp := Prefix (Exp);
9274             goto Continue;
9275
9276          else
9277             return;
9278          end if;
9279
9280          --  Now look for entity being referenced
9281
9282          if Present (Ent) then
9283             if Is_Object (Ent) then
9284                if Comes_From_Source (Exp)
9285                  or else Modification_Comes_From_Source
9286                then
9287                   if Has_Pragma_Unmodified (Ent) then
9288                      Error_Msg_NE ("?pragma Unmodified given for &!", N, Ent);
9289                   end if;
9290
9291                   Set_Never_Set_In_Source (Ent, False);
9292                end if;
9293
9294                Set_Is_True_Constant (Ent, False);
9295                Set_Current_Value    (Ent, Empty);
9296                Set_Is_Known_Null    (Ent, False);
9297
9298                if not Can_Never_Be_Null (Ent) then
9299                   Set_Is_Known_Non_Null (Ent, False);
9300                end if;
9301
9302                --  Follow renaming chain
9303
9304                if (Ekind (Ent) = E_Variable or else Ekind (Ent) = E_Constant)
9305                  and then Present (Renamed_Object (Ent))
9306                then
9307                   Exp := Renamed_Object (Ent);
9308                   goto Continue;
9309                end if;
9310
9311                --  Generate a reference only if the assignment comes from
9312                --  source. This excludes, for example, calls to a dispatching
9313                --  assignment operation when the left-hand side is tagged.
9314
9315                if Modification_Comes_From_Source then
9316                   Generate_Reference (Ent, Exp, 'm');
9317                end if;
9318
9319                Check_Nested_Access (Ent);
9320             end if;
9321
9322             Kill_Checks (Ent);
9323
9324             --  If we are sure this is a modification from source, and we know
9325             --  this modifies a constant, then give an appropriate warning.
9326
9327             if Overlays_Constant (Ent)
9328               and then Modification_Comes_From_Source
9329               and then Sure
9330             then
9331                declare
9332                   A : constant Node_Id := Address_Clause (Ent);
9333                begin
9334                   if Present (A) then
9335                      declare
9336                         Exp : constant Node_Id := Expression (A);
9337                      begin
9338                         if Nkind (Exp) = N_Attribute_Reference
9339                           and then Attribute_Name (Exp) = Name_Address
9340                           and then Is_Entity_Name (Prefix (Exp))
9341                         then
9342                            Error_Msg_Sloc := Sloc (A);
9343                            Error_Msg_NE
9344                              ("constant& may be modified via address clause#?",
9345                               N, Entity (Prefix (Exp)));
9346                         end if;
9347                      end;
9348                   end if;
9349                end;
9350             end if;
9351
9352             return;
9353          end if;
9354       end loop;
9355    end Note_Possible_Modification;
9356
9357    -------------------------
9358    -- Object_Access_Level --
9359    -------------------------
9360
9361    function Object_Access_Level (Obj : Node_Id) return Uint is
9362       E : Entity_Id;
9363
9364    --  Returns the static accessibility level of the view denoted by Obj. Note
9365    --  that the value returned is the result of a call to Scope_Depth. Only
9366    --  scope depths associated with dynamic scopes can actually be returned.
9367    --  Since only relative levels matter for accessibility checking, the fact
9368    --  that the distance between successive levels of accessibility is not
9369    --  always one is immaterial (invariant: if level(E2) is deeper than
9370    --  level(E1), then Scope_Depth(E1) < Scope_Depth(E2)).
9371
9372       function Reference_To (Obj : Node_Id) return Node_Id;
9373       --  An explicit dereference is created when removing side-effects from
9374       --  expressions for constraint checking purposes. In this case a local
9375       --  access type is created for it. The correct access level is that of
9376       --  the original source node. We detect this case by noting that the
9377       --  prefix of the dereference is created by an object declaration whose
9378       --  initial expression is a reference.
9379
9380       ------------------
9381       -- Reference_To --
9382       ------------------
9383
9384       function Reference_To (Obj : Node_Id) return Node_Id is
9385          Pref : constant Node_Id := Prefix (Obj);
9386       begin
9387          if Is_Entity_Name (Pref)
9388            and then Nkind (Parent (Entity (Pref))) = N_Object_Declaration
9389            and then Present (Expression (Parent (Entity (Pref))))
9390            and then Nkind (Expression (Parent (Entity (Pref)))) = N_Reference
9391          then
9392             return (Prefix (Expression (Parent (Entity (Pref)))));
9393          else
9394             return Empty;
9395          end if;
9396       end Reference_To;
9397
9398    --  Start of processing for Object_Access_Level
9399
9400    begin
9401       if Is_Entity_Name (Obj) then
9402          E := Entity (Obj);
9403
9404          if Is_Prival (E) then
9405             E := Prival_Link (E);
9406          end if;
9407
9408          --  If E is a type then it denotes a current instance. For this case
9409          --  we add one to the normal accessibility level of the type to ensure
9410          --  that current instances are treated as always being deeper than
9411          --  than the level of any visible named access type (see 3.10.2(21)).
9412
9413          if Is_Type (E) then
9414             return Type_Access_Level (E) +  1;
9415
9416          elsif Present (Renamed_Object (E)) then
9417             return Object_Access_Level (Renamed_Object (E));
9418
9419          --  Similarly, if E is a component of the current instance of a
9420          --  protected type, any instance of it is assumed to be at a deeper
9421          --  level than the type. For a protected object (whose type is an
9422          --  anonymous protected type) its components are at the same level
9423          --  as the type itself.
9424
9425          elsif not Is_Overloadable (E)
9426            and then Ekind (Scope (E)) = E_Protected_Type
9427            and then Comes_From_Source (Scope (E))
9428          then
9429             return Type_Access_Level (Scope (E)) + 1;
9430
9431          else
9432             return Scope_Depth (Enclosing_Dynamic_Scope (E));
9433          end if;
9434
9435       elsif Nkind (Obj) = N_Selected_Component then
9436          if Is_Access_Type (Etype (Prefix (Obj))) then
9437             return Type_Access_Level (Etype (Prefix (Obj)));
9438          else
9439             return Object_Access_Level (Prefix (Obj));
9440          end if;
9441
9442       elsif Nkind (Obj) = N_Indexed_Component then
9443          if Is_Access_Type (Etype (Prefix (Obj))) then
9444             return Type_Access_Level (Etype (Prefix (Obj)));
9445          else
9446             return Object_Access_Level (Prefix (Obj));
9447          end if;
9448
9449       elsif Nkind (Obj) = N_Explicit_Dereference then
9450
9451          --  If the prefix is a selected access discriminant then we make a
9452          --  recursive call on the prefix, which will in turn check the level
9453          --  of the prefix object of the selected discriminant.
9454
9455          if Nkind (Prefix (Obj)) = N_Selected_Component
9456            and then Ekind (Etype (Prefix (Obj))) = E_Anonymous_Access_Type
9457            and then
9458              Ekind (Entity (Selector_Name (Prefix (Obj)))) = E_Discriminant
9459          then
9460             return Object_Access_Level (Prefix (Obj));
9461
9462          elsif not (Comes_From_Source (Obj)) then
9463             declare
9464                Ref : constant Node_Id := Reference_To (Obj);
9465             begin
9466                if Present (Ref) then
9467                   return Object_Access_Level (Ref);
9468                else
9469                   return Type_Access_Level (Etype (Prefix (Obj)));
9470                end if;
9471             end;
9472
9473          else
9474             return Type_Access_Level (Etype (Prefix (Obj)));
9475          end if;
9476
9477       elsif Nkind (Obj) = N_Type_Conversion
9478         or else Nkind (Obj) = N_Unchecked_Type_Conversion
9479       then
9480          return Object_Access_Level (Expression (Obj));
9481
9482       --  Function results are objects, so we get either the access level of
9483       --  the function or, in the case of an indirect call, the level of the
9484       --  access-to-subprogram type.
9485
9486       elsif Nkind (Obj) = N_Function_Call then
9487          if Is_Entity_Name (Name (Obj)) then
9488             return Subprogram_Access_Level (Entity (Name (Obj)));
9489          else
9490             return Type_Access_Level (Etype (Prefix (Name (Obj))));
9491          end if;
9492
9493       --  For convenience we handle qualified expressions, even though
9494       --  they aren't technically object names.
9495
9496       elsif Nkind (Obj) = N_Qualified_Expression then
9497          return Object_Access_Level (Expression (Obj));
9498
9499       --  Otherwise return the scope level of Standard.
9500       --  (If there are cases that fall through
9501       --  to this point they will be treated as
9502       --  having global accessibility for now. ???)
9503
9504       else
9505          return Scope_Depth (Standard_Standard);
9506       end if;
9507    end Object_Access_Level;
9508
9509    -----------------------
9510    -- Private_Component --
9511    -----------------------
9512
9513    function Private_Component (Type_Id : Entity_Id) return Entity_Id is
9514       Ancestor  : constant Entity_Id := Base_Type (Type_Id);
9515
9516       function Trace_Components
9517         (T     : Entity_Id;
9518          Check : Boolean) return Entity_Id;
9519       --  Recursive function that does the work, and checks against circular
9520       --  definition for each subcomponent type.
9521
9522       ----------------------
9523       -- Trace_Components --
9524       ----------------------
9525
9526       function Trace_Components
9527          (T     : Entity_Id;
9528           Check : Boolean) return Entity_Id
9529        is
9530          Btype     : constant Entity_Id := Base_Type (T);
9531          Component : Entity_Id;
9532          P         : Entity_Id;
9533          Candidate : Entity_Id := Empty;
9534
9535       begin
9536          if Check and then Btype = Ancestor then
9537             Error_Msg_N ("circular type definition", Type_Id);
9538             return Any_Type;
9539          end if;
9540
9541          if Is_Private_Type (Btype)
9542            and then not Is_Generic_Type (Btype)
9543          then
9544             if Present (Full_View (Btype))
9545               and then Is_Record_Type (Full_View (Btype))
9546               and then not Is_Frozen (Btype)
9547             then
9548                --  To indicate that the ancestor depends on a private type, the
9549                --  current Btype is sufficient. However, to check for circular
9550                --  definition we must recurse on the full view.
9551
9552                Candidate := Trace_Components (Full_View (Btype), True);
9553
9554                if Candidate = Any_Type then
9555                   return Any_Type;
9556                else
9557                   return Btype;
9558                end if;
9559
9560             else
9561                return Btype;
9562             end if;
9563
9564          elsif Is_Array_Type (Btype) then
9565             return Trace_Components (Component_Type (Btype), True);
9566
9567          elsif Is_Record_Type (Btype) then
9568             Component := First_Entity (Btype);
9569             while Present (Component) loop
9570
9571                --  Skip anonymous types generated by constrained components
9572
9573                if not Is_Type (Component) then
9574                   P := Trace_Components (Etype (Component), True);
9575
9576                   if Present (P) then
9577                      if P = Any_Type then
9578                         return P;
9579                      else
9580                         Candidate := P;
9581                      end if;
9582                   end if;
9583                end if;
9584
9585                Next_Entity (Component);
9586             end loop;
9587
9588             return Candidate;
9589
9590          else
9591             return Empty;
9592          end if;
9593       end Trace_Components;
9594
9595    --  Start of processing for Private_Component
9596
9597    begin
9598       return Trace_Components (Type_Id, False);
9599    end Private_Component;
9600
9601    ---------------------------
9602    -- Primitive_Names_Match --
9603    ---------------------------
9604
9605    function Primitive_Names_Match (E1, E2 : Entity_Id) return Boolean is
9606
9607       function Non_Internal_Name (E : Entity_Id) return Name_Id;
9608       --  Given an internal name, returns the corresponding non-internal name
9609
9610       ------------------------
9611       --  Non_Internal_Name --
9612       ------------------------
9613
9614       function Non_Internal_Name (E : Entity_Id) return Name_Id is
9615       begin
9616          Get_Name_String (Chars (E));
9617          Name_Len := Name_Len - 1;
9618          return Name_Find;
9619       end Non_Internal_Name;
9620
9621    --  Start of processing for Primitive_Names_Match
9622
9623    begin
9624       pragma Assert (Present (E1) and then Present (E2));
9625
9626       return Chars (E1) = Chars (E2)
9627         or else
9628            (not Is_Internal_Name (Chars (E1))
9629               and then Is_Internal_Name (Chars (E2))
9630               and then Non_Internal_Name (E2) = Chars (E1))
9631         or else
9632            (not Is_Internal_Name (Chars (E2))
9633               and then Is_Internal_Name (Chars (E1))
9634               and then Non_Internal_Name (E1) = Chars (E2))
9635         or else
9636            (Is_Predefined_Dispatching_Operation (E1)
9637               and then Is_Predefined_Dispatching_Operation (E2)
9638               and then Same_TSS (E1, E2))
9639         or else
9640            (Is_Init_Proc (E1) and then Is_Init_Proc (E2));
9641    end Primitive_Names_Match;
9642
9643    -----------------------
9644    -- Process_End_Label --
9645    -----------------------
9646
9647    procedure Process_End_Label
9648      (N   : Node_Id;
9649       Typ : Character;
9650       Ent  : Entity_Id)
9651    is
9652       Loc  : Source_Ptr;
9653       Nam  : Node_Id;
9654       Scop : Entity_Id;
9655
9656       Label_Ref : Boolean;
9657       --  Set True if reference to end label itself is required
9658
9659       Endl : Node_Id;
9660       --  Gets set to the operator symbol or identifier that references the
9661       --  entity Ent. For the child unit case, this is the identifier from the
9662       --  designator. For other cases, this is simply Endl.
9663
9664       procedure Generate_Parent_Ref (N : Node_Id; E : Entity_Id);
9665       --  N is an identifier node that appears as a parent unit reference in
9666       --  the case where Ent is a child unit. This procedure generates an
9667       --  appropriate cross-reference entry. E is the corresponding entity.
9668
9669       -------------------------
9670       -- Generate_Parent_Ref --
9671       -------------------------
9672
9673       procedure Generate_Parent_Ref (N : Node_Id; E : Entity_Id) is
9674       begin
9675          --  If names do not match, something weird, skip reference
9676
9677          if Chars (E) = Chars (N) then
9678
9679             --  Generate the reference. We do NOT consider this as a reference
9680             --  for unreferenced symbol purposes.
9681
9682             Generate_Reference (E, N, 'r', Set_Ref => False, Force => True);
9683
9684             if Style_Check then
9685                Style.Check_Identifier (N, E);
9686             end if;
9687          end if;
9688       end Generate_Parent_Ref;
9689
9690    --  Start of processing for Process_End_Label
9691
9692    begin
9693       --  If no node, ignore. This happens in some error situations, and
9694       --  also for some internally generated structures where no end label
9695       --  references are required in any case.
9696
9697       if No (N) then
9698          return;
9699       end if;
9700
9701       --  Nothing to do if no End_Label, happens for internally generated
9702       --  constructs where we don't want an end label reference anyway. Also
9703       --  nothing to do if Endl is a string literal, which means there was
9704       --  some prior error (bad operator symbol)
9705
9706       Endl := End_Label (N);
9707
9708       if No (Endl) or else Nkind (Endl) = N_String_Literal then
9709          return;
9710       end if;
9711
9712       --  Reference node is not in extended main source unit
9713
9714       if not In_Extended_Main_Source_Unit (N) then
9715
9716          --  Generally we do not collect references except for the extended
9717          --  main source unit. The one exception is the 'e' entry for a
9718          --  package spec, where it is useful for a client to have the
9719          --  ending information to define scopes.
9720
9721          if Typ /= 'e' then
9722             return;
9723
9724          else
9725             Label_Ref := False;
9726
9727             --  For this case, we can ignore any parent references, but we
9728             --  need the package name itself for the 'e' entry.
9729
9730             if Nkind (Endl) = N_Designator then
9731                Endl := Identifier (Endl);
9732             end if;
9733          end if;
9734
9735       --  Reference is in extended main source unit
9736
9737       else
9738          Label_Ref := True;
9739
9740          --  For designator, generate references for the parent entries
9741
9742          if Nkind (Endl) = N_Designator then
9743
9744             --  Generate references for the prefix if the END line comes from
9745             --  source (otherwise we do not need these references) We climb the
9746             --  scope stack to find the expected entities.
9747
9748             if Comes_From_Source (Endl) then
9749                Nam  := Name (Endl);
9750                Scop := Current_Scope;
9751                while Nkind (Nam) = N_Selected_Component loop
9752                   Scop := Scope (Scop);
9753                   exit when No (Scop);
9754                   Generate_Parent_Ref (Selector_Name (Nam), Scop);
9755                   Nam := Prefix (Nam);
9756                end loop;
9757
9758                if Present (Scop) then
9759                   Generate_Parent_Ref (Nam, Scope (Scop));
9760                end if;
9761             end if;
9762
9763             Endl := Identifier (Endl);
9764          end if;
9765       end if;
9766
9767       --  If the end label is not for the given entity, then either we have
9768       --  some previous error, or this is a generic instantiation for which
9769       --  we do not need to make a cross-reference in this case anyway. In
9770       --  either case we simply ignore the call.
9771
9772       if Chars (Ent) /= Chars (Endl) then
9773          return;
9774       end if;
9775
9776       --  If label was really there, then generate a normal reference and then
9777       --  adjust the location in the end label to point past the name (which
9778       --  should almost always be the semicolon).
9779
9780       Loc := Sloc (Endl);
9781
9782       if Comes_From_Source (Endl) then
9783
9784          --  If a label reference is required, then do the style check and
9785          --  generate an l-type cross-reference entry for the label
9786
9787          if Label_Ref then
9788             if Style_Check then
9789                Style.Check_Identifier (Endl, Ent);
9790             end if;
9791
9792             Generate_Reference (Ent, Endl, 'l', Set_Ref => False);
9793          end if;
9794
9795          --  Set the location to point past the label (normally this will
9796          --  mean the semicolon immediately following the label). This is
9797          --  done for the sake of the 'e' or 't' entry generated below.
9798
9799          Get_Decoded_Name_String (Chars (Endl));
9800          Set_Sloc (Endl, Sloc (Endl) + Source_Ptr (Name_Len));
9801       end if;
9802
9803       --  Now generate the e/t reference
9804
9805       Generate_Reference (Ent, Endl, Typ, Set_Ref => False, Force => True);
9806
9807       --  Restore Sloc, in case modified above, since we have an identifier
9808       --  and the normal Sloc should be left set in the tree.
9809
9810       Set_Sloc (Endl, Loc);
9811    end Process_End_Label;
9812
9813    ------------------
9814    -- Real_Convert --
9815    ------------------
9816
9817    --  We do the conversion to get the value of the real string by using
9818    --  the scanner, see Sinput for details on use of the internal source
9819    --  buffer for scanning internal strings.
9820
9821    function Real_Convert (S : String) return Node_Id is
9822       Save_Src : constant Source_Buffer_Ptr := Source;
9823       Negative : Boolean;
9824
9825    begin
9826       Source := Internal_Source_Ptr;
9827       Scan_Ptr := 1;
9828
9829       for J in S'Range loop
9830          Source (Source_Ptr (J)) := S (J);
9831       end loop;
9832
9833       Source (S'Length + 1) := EOF;
9834
9835       if Source (Scan_Ptr) = '-' then
9836          Negative := True;
9837          Scan_Ptr := Scan_Ptr + 1;
9838       else
9839          Negative := False;
9840       end if;
9841
9842       Scan;
9843
9844       if Negative then
9845          Set_Realval (Token_Node, UR_Negate (Realval (Token_Node)));
9846       end if;
9847
9848       Source := Save_Src;
9849       return Token_Node;
9850    end Real_Convert;
9851
9852    ------------------------------------
9853    -- References_Generic_Formal_Type --
9854    ------------------------------------
9855
9856    function References_Generic_Formal_Type (N : Node_Id) return Boolean is
9857
9858       function Process (N : Node_Id) return Traverse_Result;
9859       --  Process one node in search for generic formal type
9860
9861       -------------
9862       -- Process --
9863       -------------
9864
9865       function Process (N : Node_Id) return Traverse_Result is
9866       begin
9867          if Nkind (N) in N_Has_Entity then
9868             declare
9869                E : constant Entity_Id := Entity (N);
9870             begin
9871                if Present (E) then
9872                   if Is_Generic_Type (E) then
9873                      return Abandon;
9874                   elsif Present (Etype (E))
9875                     and then Is_Generic_Type (Etype (E))
9876                   then
9877                      return Abandon;
9878                   end if;
9879                end if;
9880             end;
9881          end if;
9882
9883          return Atree.OK;
9884       end Process;
9885
9886       function Traverse is new Traverse_Func (Process);
9887       --  Traverse tree to look for generic type
9888
9889    begin
9890       if Inside_A_Generic then
9891          return Traverse (N) = Abandon;
9892       else
9893          return False;
9894       end if;
9895    end References_Generic_Formal_Type;
9896
9897    --------------------
9898    -- Remove_Homonym --
9899    --------------------
9900
9901    procedure Remove_Homonym (E : Entity_Id) is
9902       Prev  : Entity_Id := Empty;
9903       H     : Entity_Id;
9904
9905    begin
9906       if E = Current_Entity (E) then
9907          if Present (Homonym (E)) then
9908             Set_Current_Entity (Homonym (E));
9909          else
9910             Set_Name_Entity_Id (Chars (E), Empty);
9911          end if;
9912       else
9913          H := Current_Entity (E);
9914          while Present (H) and then H /= E loop
9915             Prev := H;
9916             H    := Homonym (H);
9917          end loop;
9918
9919          Set_Homonym (Prev, Homonym (E));
9920       end if;
9921    end Remove_Homonym;
9922
9923    ---------------------
9924    -- Rep_To_Pos_Flag --
9925    ---------------------
9926
9927    function Rep_To_Pos_Flag (E : Entity_Id; Loc : Source_Ptr) return Node_Id is
9928    begin
9929       return New_Occurrence_Of
9930                (Boolean_Literals (not Range_Checks_Suppressed (E)), Loc);
9931    end Rep_To_Pos_Flag;
9932
9933    --------------------
9934    -- Require_Entity --
9935    --------------------
9936
9937    procedure Require_Entity (N : Node_Id) is
9938    begin
9939       if Is_Entity_Name (N) and then No (Entity (N)) then
9940          if Total_Errors_Detected /= 0 then
9941             Set_Entity (N, Any_Id);
9942          else
9943             raise Program_Error;
9944          end if;
9945       end if;
9946    end Require_Entity;
9947
9948    ------------------------------
9949    -- Requires_Transient_Scope --
9950    ------------------------------
9951
9952    --  A transient scope is required when variable-sized temporaries are
9953    --  allocated in the primary or secondary stack, or when finalization
9954    --  actions must be generated before the next instruction.
9955
9956    function Requires_Transient_Scope (Id : Entity_Id) return Boolean is
9957       Typ : constant Entity_Id := Underlying_Type (Id);
9958
9959    --  Start of processing for Requires_Transient_Scope
9960
9961    begin
9962       --  This is a private type which is not completed yet. This can only
9963       --  happen in a default expression (of a formal parameter or of a
9964       --  record component). Do not expand transient scope in this case
9965
9966       if No (Typ) then
9967          return False;
9968
9969       --  Do not expand transient scope for non-existent procedure return
9970
9971       elsif Typ = Standard_Void_Type then
9972          return False;
9973
9974       --  Elementary types do not require a transient scope
9975
9976       elsif Is_Elementary_Type (Typ) then
9977          return False;
9978
9979       --  Generally, indefinite subtypes require a transient scope, since the
9980       --  back end cannot generate temporaries, since this is not a valid type
9981       --  for declaring an object. It might be possible to relax this in the
9982       --  future, e.g. by declaring the maximum possible space for the type.
9983
9984       elsif Is_Indefinite_Subtype (Typ) then
9985          return True;
9986
9987       --  Functions returning tagged types may dispatch on result so their
9988       --  returned value is allocated on the secondary stack. Controlled
9989       --  type temporaries need finalization.
9990
9991       elsif Is_Tagged_Type (Typ)
9992         or else Has_Controlled_Component (Typ)
9993       then
9994          return not Is_Value_Type (Typ);
9995
9996       --  Record type
9997
9998       elsif Is_Record_Type (Typ) then
9999          declare
10000             Comp : Entity_Id;
10001          begin
10002             Comp := First_Entity (Typ);
10003             while Present (Comp) loop
10004                if Ekind (Comp) = E_Component
10005                   and then Requires_Transient_Scope (Etype (Comp))
10006                then
10007                   return True;
10008                else
10009                   Next_Entity (Comp);
10010                end if;
10011             end loop;
10012          end;
10013
10014          return False;
10015
10016       --  String literal types never require transient scope
10017
10018       elsif Ekind (Typ) = E_String_Literal_Subtype then
10019          return False;
10020
10021       --  Array type. Note that we already know that this is a constrained
10022       --  array, since unconstrained arrays will fail the indefinite test.
10023
10024       elsif Is_Array_Type (Typ) then
10025
10026          --  If component type requires a transient scope, the array does too
10027
10028          if Requires_Transient_Scope (Component_Type (Typ)) then
10029             return True;
10030
10031          --  Otherwise, we only need a transient scope if the size is not
10032          --  known at compile time.
10033
10034          else
10035             return not Size_Known_At_Compile_Time (Typ);
10036          end if;
10037
10038       --  All other cases do not require a transient scope
10039
10040       else
10041          return False;
10042       end if;
10043    end Requires_Transient_Scope;
10044
10045    --------------------------
10046    -- Reset_Analyzed_Flags --
10047    --------------------------
10048
10049    procedure Reset_Analyzed_Flags (N : Node_Id) is
10050
10051       function Clear_Analyzed (N : Node_Id) return Traverse_Result;
10052       --  Function used to reset Analyzed flags in tree. Note that we do
10053       --  not reset Analyzed flags in entities, since there is no need to
10054       --  reanalyze entities, and indeed, it is wrong to do so, since it
10055       --  can result in generating auxiliary stuff more than once.
10056
10057       --------------------
10058       -- Clear_Analyzed --
10059       --------------------
10060
10061       function Clear_Analyzed (N : Node_Id) return Traverse_Result is
10062       begin
10063          if not Has_Extension (N) then
10064             Set_Analyzed (N, False);
10065          end if;
10066
10067          return OK;
10068       end Clear_Analyzed;
10069
10070       procedure Reset_Analyzed is new Traverse_Proc (Clear_Analyzed);
10071
10072    --  Start of processing for Reset_Analyzed_Flags
10073
10074    begin
10075       Reset_Analyzed (N);
10076    end Reset_Analyzed_Flags;
10077
10078    ---------------------------
10079    -- Safe_To_Capture_Value --
10080    ---------------------------
10081
10082    function Safe_To_Capture_Value
10083      (N    : Node_Id;
10084       Ent  : Entity_Id;
10085       Cond : Boolean := False) return Boolean
10086    is
10087    begin
10088       --  The only entities for which we track constant values are variables
10089       --  which are not renamings, constants, out parameters, and in out
10090       --  parameters, so check if we have this case.
10091
10092       --  Note: it may seem odd to track constant values for constants, but in
10093       --  fact this routine is used for other purposes than simply capturing
10094       --  the value. In particular, the setting of Known[_Non]_Null.
10095
10096       if (Ekind (Ent) = E_Variable and then No (Renamed_Object (Ent)))
10097             or else
10098           Ekind (Ent) = E_Constant
10099             or else
10100           Ekind (Ent) = E_Out_Parameter
10101             or else
10102           Ekind (Ent) = E_In_Out_Parameter
10103       then
10104          null;
10105
10106       --  For conditionals, we also allow loop parameters and all formals,
10107       --  including in parameters.
10108
10109       elsif Cond
10110         and then
10111           (Ekind (Ent) = E_Loop_Parameter
10112              or else
10113            Ekind (Ent) = E_In_Parameter)
10114       then
10115          null;
10116
10117       --  For all other cases, not just unsafe, but impossible to capture
10118       --  Current_Value, since the above are the only entities which have
10119       --  Current_Value fields.
10120
10121       else
10122          return False;
10123       end if;
10124
10125       --  Skip if volatile or aliased, since funny things might be going on in
10126       --  these cases which we cannot necessarily track. Also skip any variable
10127       --  for which an address clause is given, or whose address is taken. Also
10128       --  never capture value of library level variables (an attempt to do so
10129       --  can occur in the case of package elaboration code).
10130
10131       if Treat_As_Volatile (Ent)
10132         or else Is_Aliased (Ent)
10133         or else Present (Address_Clause (Ent))
10134         or else Address_Taken (Ent)
10135         or else (Is_Library_Level_Entity (Ent)
10136                    and then Ekind (Ent) = E_Variable)
10137       then
10138          return False;
10139       end if;
10140
10141       --  OK, all above conditions are met. We also require that the scope of
10142       --  the reference be the same as the scope of the entity, not counting
10143       --  packages and blocks and loops.
10144
10145       declare
10146          E_Scope : constant Entity_Id := Scope (Ent);
10147          R_Scope : Entity_Id;
10148
10149       begin
10150          R_Scope := Current_Scope;
10151          while R_Scope /= Standard_Standard loop
10152             exit when R_Scope = E_Scope;
10153
10154             if Ekind (R_Scope) /= E_Package
10155                   and then
10156                 Ekind (R_Scope) /= E_Block
10157                   and then
10158                 Ekind (R_Scope) /= E_Loop
10159             then
10160                return False;
10161             else
10162                R_Scope := Scope (R_Scope);
10163             end if;
10164          end loop;
10165       end;
10166
10167       --  We also require that the reference does not appear in a context
10168       --  where it is not sure to be executed (i.e. a conditional context
10169       --  or an exception handler). We skip this if Cond is True, since the
10170       --  capturing of values from conditional tests handles this ok.
10171
10172       if Cond then
10173          return True;
10174       end if;
10175
10176       declare
10177          Desc : Node_Id;
10178          P    : Node_Id;
10179
10180       begin
10181          Desc := N;
10182
10183          P := Parent (N);
10184          while Present (P) loop
10185             if         Nkind (P) = N_If_Statement
10186               or else  Nkind (P) = N_Case_Statement
10187               or else (Nkind (P) in N_Short_Circuit
10188                          and then Desc = Right_Opnd (P))
10189               or else (Nkind (P) = N_Conditional_Expression
10190                          and then Desc /= First (Expressions (P)))
10191               or else  Nkind (P) = N_Exception_Handler
10192               or else  Nkind (P) = N_Selective_Accept
10193               or else  Nkind (P) = N_Conditional_Entry_Call
10194               or else  Nkind (P) = N_Timed_Entry_Call
10195               or else  Nkind (P) = N_Asynchronous_Select
10196             then
10197                return False;
10198             else
10199                Desc := P;
10200                P    := Parent (P);
10201             end if;
10202          end loop;
10203       end;
10204
10205       --  OK, looks safe to set value
10206
10207       return True;
10208    end Safe_To_Capture_Value;
10209
10210    ---------------
10211    -- Same_Name --
10212    ---------------
10213
10214    function Same_Name (N1, N2 : Node_Id) return Boolean is
10215       K1 : constant Node_Kind := Nkind (N1);
10216       K2 : constant Node_Kind := Nkind (N2);
10217
10218    begin
10219       if (K1 = N_Identifier or else K1 = N_Defining_Identifier)
10220         and then (K2 = N_Identifier or else K2 = N_Defining_Identifier)
10221       then
10222          return Chars (N1) = Chars (N2);
10223
10224       elsif (K1 = N_Selected_Component or else K1 = N_Expanded_Name)
10225         and then (K2 = N_Selected_Component or else K2 = N_Expanded_Name)
10226       then
10227          return Same_Name (Selector_Name (N1), Selector_Name (N2))
10228            and then Same_Name (Prefix (N1), Prefix (N2));
10229
10230       else
10231          return False;
10232       end if;
10233    end Same_Name;
10234
10235    -----------------
10236    -- Same_Object --
10237    -----------------
10238
10239    function Same_Object (Node1, Node2 : Node_Id) return Boolean is
10240       N1 : constant Node_Id := Original_Node (Node1);
10241       N2 : constant Node_Id := Original_Node (Node2);
10242       --  We do the tests on original nodes, since we are most interested
10243       --  in the original source, not any expansion that got in the way.
10244
10245       K1 : constant Node_Kind := Nkind (N1);
10246       K2 : constant Node_Kind := Nkind (N2);
10247
10248    begin
10249       --  First case, both are entities with same entity
10250
10251       if K1 in N_Has_Entity
10252         and then K2 in N_Has_Entity
10253         and then Present (Entity (N1))
10254         and then Present (Entity (N2))
10255         and then (Ekind (Entity (N1)) = E_Variable
10256                     or else
10257                   Ekind (Entity (N1)) = E_Constant)
10258         and then Entity (N1) = Entity (N2)
10259       then
10260          return True;
10261
10262       --  Second case, selected component with same selector, same record
10263
10264       elsif K1 = N_Selected_Component
10265         and then K2 = N_Selected_Component
10266         and then Chars (Selector_Name (N1)) = Chars (Selector_Name (N2))
10267       then
10268          return Same_Object (Prefix (N1), Prefix (N2));
10269
10270       --  Third case, indexed component with same subscripts, same array
10271
10272       elsif K1 = N_Indexed_Component
10273         and then K2 = N_Indexed_Component
10274         and then Same_Object (Prefix (N1), Prefix (N2))
10275       then
10276          declare
10277             E1, E2 : Node_Id;
10278          begin
10279             E1 := First (Expressions (N1));
10280             E2 := First (Expressions (N2));
10281             while Present (E1) loop
10282                if not Same_Value (E1, E2) then
10283                   return False;
10284                else
10285                   Next (E1);
10286                   Next (E2);
10287                end if;
10288             end loop;
10289
10290             return True;
10291          end;
10292
10293       --  Fourth case, slice of same array with same bounds
10294
10295       elsif K1 = N_Slice
10296         and then K2 = N_Slice
10297         and then Nkind (Discrete_Range (N1)) = N_Range
10298         and then Nkind (Discrete_Range (N2)) = N_Range
10299         and then Same_Value (Low_Bound (Discrete_Range (N1)),
10300                              Low_Bound (Discrete_Range (N2)))
10301         and then Same_Value (High_Bound (Discrete_Range (N1)),
10302                              High_Bound (Discrete_Range (N2)))
10303       then
10304          return Same_Name (Prefix (N1), Prefix (N2));
10305
10306       --  All other cases, not clearly the same object
10307
10308       else
10309          return False;
10310       end if;
10311    end Same_Object;
10312
10313    ---------------
10314    -- Same_Type --
10315    ---------------
10316
10317    function Same_Type (T1, T2 : Entity_Id) return Boolean is
10318    begin
10319       if T1 = T2 then
10320          return True;
10321
10322       elsif not Is_Constrained (T1)
10323         and then not Is_Constrained (T2)
10324         and then Base_Type (T1) = Base_Type (T2)
10325       then
10326          return True;
10327
10328       --  For now don't bother with case of identical constraints, to be
10329       --  fiddled with later on perhaps (this is only used for optimization
10330       --  purposes, so it is not critical to do a best possible job)
10331
10332       else
10333          return False;
10334       end if;
10335    end Same_Type;
10336
10337    ----------------
10338    -- Same_Value --
10339    ----------------
10340
10341    function Same_Value (Node1, Node2 : Node_Id) return Boolean is
10342    begin
10343       if Compile_Time_Known_Value (Node1)
10344         and then Compile_Time_Known_Value (Node2)
10345         and then Expr_Value (Node1) = Expr_Value (Node2)
10346       then
10347          return True;
10348       elsif Same_Object (Node1, Node2) then
10349          return True;
10350       else
10351          return False;
10352       end if;
10353    end Same_Value;
10354
10355    ------------------------
10356    -- Scope_Is_Transient --
10357    ------------------------
10358
10359    function Scope_Is_Transient return Boolean is
10360    begin
10361       return Scope_Stack.Table (Scope_Stack.Last).Is_Transient;
10362    end Scope_Is_Transient;
10363
10364    ------------------
10365    -- Scope_Within --
10366    ------------------
10367
10368    function Scope_Within (Scope1, Scope2 : Entity_Id) return Boolean is
10369       Scop : Entity_Id;
10370
10371    begin
10372       Scop := Scope1;
10373       while Scop /= Standard_Standard loop
10374          Scop := Scope (Scop);
10375
10376          if Scop = Scope2 then
10377             return True;
10378          end if;
10379       end loop;
10380
10381       return False;
10382    end Scope_Within;
10383
10384    --------------------------
10385    -- Scope_Within_Or_Same --
10386    --------------------------
10387
10388    function Scope_Within_Or_Same (Scope1, Scope2 : Entity_Id) return Boolean is
10389       Scop : Entity_Id;
10390
10391    begin
10392       Scop := Scope1;
10393       while Scop /= Standard_Standard loop
10394          if Scop = Scope2 then
10395             return True;
10396          else
10397             Scop := Scope (Scop);
10398          end if;
10399       end loop;
10400
10401       return False;
10402    end Scope_Within_Or_Same;
10403
10404    --------------------
10405    -- Set_Convention --
10406    --------------------
10407
10408    procedure Set_Convention (E : Entity_Id; Val : Snames.Convention_Id) is
10409    begin
10410       Basic_Set_Convention (E, Val);
10411
10412       if Is_Type (E)
10413         and then Is_Access_Subprogram_Type (Base_Type (E))
10414         and then Has_Foreign_Convention (E)
10415       then
10416          Set_Can_Use_Internal_Rep (E, False);
10417       end if;
10418    end Set_Convention;
10419
10420    ------------------------
10421    -- Set_Current_Entity --
10422    ------------------------
10423
10424    --  The given entity is to be set as the currently visible definition
10425    --  of its associated name (i.e. the Node_Id associated with its name).
10426    --  All we have to do is to get the name from the identifier, and
10427    --  then set the associated Node_Id to point to the given entity.
10428
10429    procedure Set_Current_Entity (E : Entity_Id) is
10430    begin
10431       Set_Name_Entity_Id (Chars (E), E);
10432    end Set_Current_Entity;
10433
10434    ---------------------------
10435    -- Set_Debug_Info_Needed --
10436    ---------------------------
10437
10438    procedure Set_Debug_Info_Needed (T : Entity_Id) is
10439
10440       procedure Set_Debug_Info_Needed_If_Not_Set (E : Entity_Id);
10441       pragma Inline (Set_Debug_Info_Needed_If_Not_Set);
10442       --  Used to set debug info in a related node if not set already
10443
10444       --------------------------------------
10445       -- Set_Debug_Info_Needed_If_Not_Set --
10446       --------------------------------------
10447
10448       procedure Set_Debug_Info_Needed_If_Not_Set (E : Entity_Id) is
10449       begin
10450          if Present (E)
10451            and then not Needs_Debug_Info (E)
10452          then
10453             Set_Debug_Info_Needed (E);
10454
10455             --  For a private type, indicate that the full view also needs
10456             --  debug information.
10457
10458             if Is_Type (E)
10459               and then Is_Private_Type (E)
10460               and then Present (Full_View (E))
10461             then
10462                Set_Debug_Info_Needed (Full_View (E));
10463             end if;
10464          end if;
10465       end Set_Debug_Info_Needed_If_Not_Set;
10466
10467    --  Start of processing for Set_Debug_Info_Needed
10468
10469    begin
10470       --  Nothing to do if argument is Empty or has Debug_Info_Off set, which
10471       --  indicates that Debug_Info_Needed is never required for the entity.
10472
10473       if No (T)
10474         or else Debug_Info_Off (T)
10475       then
10476          return;
10477       end if;
10478
10479       --  Set flag in entity itself. Note that we will go through the following
10480       --  circuitry even if the flag is already set on T. That's intentional,
10481       --  it makes sure that the flag will be set in subsidiary entities.
10482
10483       Set_Needs_Debug_Info (T);
10484
10485       --  Set flag on subsidiary entities if not set already
10486
10487       if Is_Object (T) then
10488          Set_Debug_Info_Needed_If_Not_Set (Etype (T));
10489
10490       elsif Is_Type (T) then
10491          Set_Debug_Info_Needed_If_Not_Set (Etype (T));
10492
10493          if Is_Record_Type (T) then
10494             declare
10495                Ent : Entity_Id := First_Entity (T);
10496             begin
10497                while Present (Ent) loop
10498                   Set_Debug_Info_Needed_If_Not_Set (Ent);
10499                   Next_Entity (Ent);
10500                end loop;
10501             end;
10502
10503             --  For a class wide subtype, we also need debug information
10504             --  for the equivalent type.
10505
10506             if Ekind (T) = E_Class_Wide_Subtype then
10507                Set_Debug_Info_Needed_If_Not_Set (Equivalent_Type (T));
10508             end if;
10509
10510          elsif Is_Array_Type (T) then
10511             Set_Debug_Info_Needed_If_Not_Set (Component_Type (T));
10512
10513             declare
10514                Indx : Node_Id := First_Index (T);
10515             begin
10516                while Present (Indx) loop
10517                   Set_Debug_Info_Needed_If_Not_Set (Etype (Indx));
10518                   Indx := Next_Index (Indx);
10519                end loop;
10520             end;
10521
10522             if Is_Packed (T) then
10523                Set_Debug_Info_Needed_If_Not_Set (Packed_Array_Type (T));
10524             end if;
10525
10526          elsif Is_Access_Type (T) then
10527             Set_Debug_Info_Needed_If_Not_Set (Directly_Designated_Type (T));
10528
10529          elsif Is_Private_Type (T) then
10530             Set_Debug_Info_Needed_If_Not_Set (Full_View (T));
10531
10532          elsif Is_Protected_Type (T) then
10533             Set_Debug_Info_Needed_If_Not_Set (Corresponding_Record_Type (T));
10534          end if;
10535       end if;
10536    end Set_Debug_Info_Needed;
10537
10538    ---------------------------------
10539    -- Set_Entity_With_Style_Check --
10540    ---------------------------------
10541
10542    procedure Set_Entity_With_Style_Check (N : Node_Id; Val : Entity_Id) is
10543       Val_Actual : Entity_Id;
10544       Nod        : Node_Id;
10545
10546    begin
10547       Set_Entity (N, Val);
10548
10549       if Style_Check
10550         and then not Suppress_Style_Checks (Val)
10551         and then not In_Instance
10552       then
10553          if Nkind (N) = N_Identifier then
10554             Nod := N;
10555          elsif Nkind (N) = N_Expanded_Name then
10556             Nod := Selector_Name (N);
10557          else
10558             return;
10559          end if;
10560
10561          --  A special situation arises for derived operations, where we want
10562          --  to do the check against the parent (since the Sloc of the derived
10563          --  operation points to the derived type declaration itself).
10564
10565          Val_Actual := Val;
10566          while not Comes_From_Source (Val_Actual)
10567            and then Nkind (Val_Actual) in N_Entity
10568            and then (Ekind (Val_Actual) = E_Enumeration_Literal
10569                       or else Is_Subprogram (Val_Actual)
10570                       or else Is_Generic_Subprogram (Val_Actual))
10571            and then Present (Alias (Val_Actual))
10572          loop
10573             Val_Actual := Alias (Val_Actual);
10574          end loop;
10575
10576          --  Renaming declarations for generic actuals do not come from source,
10577          --  and have a different name from that of the entity they rename, so
10578          --  there is no style check to perform here.
10579
10580          if Chars (Nod) = Chars (Val_Actual) then
10581             Style.Check_Identifier (Nod, Val_Actual);
10582          end if;
10583       end if;
10584
10585       Set_Entity (N, Val);
10586    end Set_Entity_With_Style_Check;
10587
10588    ------------------------
10589    -- Set_Name_Entity_Id --
10590    ------------------------
10591
10592    procedure Set_Name_Entity_Id (Id : Name_Id; Val : Entity_Id) is
10593    begin
10594       Set_Name_Table_Info (Id, Int (Val));
10595    end Set_Name_Entity_Id;
10596
10597    ---------------------
10598    -- Set_Next_Actual --
10599    ---------------------
10600
10601    procedure Set_Next_Actual (Ass1_Id : Node_Id; Ass2_Id : Node_Id) is
10602    begin
10603       if Nkind (Parent (Ass1_Id)) = N_Parameter_Association then
10604          Set_First_Named_Actual (Parent (Ass1_Id), Ass2_Id);
10605       end if;
10606    end Set_Next_Actual;
10607
10608    ----------------------------------
10609    -- Set_Optimize_Alignment_Flags --
10610    ----------------------------------
10611
10612    procedure Set_Optimize_Alignment_Flags (E : Entity_Id) is
10613    begin
10614       if Optimize_Alignment = 'S' then
10615          Set_Optimize_Alignment_Space (E);
10616       elsif Optimize_Alignment = 'T' then
10617          Set_Optimize_Alignment_Time (E);
10618       end if;
10619    end Set_Optimize_Alignment_Flags;
10620
10621    -----------------------
10622    -- Set_Public_Status --
10623    -----------------------
10624
10625    procedure Set_Public_Status (Id : Entity_Id) is
10626       S : constant Entity_Id := Current_Scope;
10627
10628       function Within_HSS_Or_If (E : Entity_Id) return Boolean;
10629       --  Determines if E is defined within handled statement sequence or
10630       --  an if statement, returns True if so, False otherwise.
10631
10632       ----------------------
10633       -- Within_HSS_Or_If --
10634       ----------------------
10635
10636       function Within_HSS_Or_If (E : Entity_Id) return Boolean is
10637          N : Node_Id;
10638       begin
10639          N := Declaration_Node (E);
10640          loop
10641             N := Parent (N);
10642
10643             if No (N) then
10644                return False;
10645
10646             elsif Nkind_In (N, N_Handled_Sequence_Of_Statements,
10647                                N_If_Statement)
10648             then
10649                return True;
10650             end if;
10651          end loop;
10652       end Within_HSS_Or_If;
10653
10654    --  Start of processing for Set_Public_Status
10655
10656    begin
10657       --  Everything in the scope of Standard is public
10658
10659       if S = Standard_Standard then
10660          Set_Is_Public (Id);
10661
10662       --  Entity is definitely not public if enclosing scope is not public
10663
10664       elsif not Is_Public (S) then
10665          return;
10666
10667       --  An object or function declaration that occurs in a handled sequence
10668       --  of statements or within an if statement is the declaration for a
10669       --  temporary object or local subprogram generated by the expander. It
10670       --  never needs to be made public and furthermore, making it public can
10671       --  cause back end problems.
10672
10673       elsif Nkind_In (Parent (Id), N_Object_Declaration,
10674                                    N_Function_Specification)
10675         and then Within_HSS_Or_If (Id)
10676       then
10677          return;
10678
10679       --  Entities in public packages or records are public
10680
10681       elsif Ekind (S) = E_Package or Is_Record_Type (S) then
10682          Set_Is_Public (Id);
10683
10684       --  The bounds of an entry family declaration can generate object
10685       --  declarations that are visible to the back-end, e.g. in the
10686       --  the declaration of a composite type that contains tasks.
10687
10688       elsif Is_Concurrent_Type (S)
10689         and then not Has_Completion (S)
10690         and then Nkind (Parent (Id)) = N_Object_Declaration
10691       then
10692          Set_Is_Public (Id);
10693       end if;
10694    end Set_Public_Status;
10695
10696    -----------------------------
10697    -- Set_Referenced_Modified --
10698    -----------------------------
10699
10700    procedure Set_Referenced_Modified (N : Node_Id; Out_Param : Boolean) is
10701       Pref : Node_Id;
10702
10703    begin
10704       --  Deal with indexed or selected component where prefix is modified
10705
10706       if Nkind_In (N, N_Indexed_Component, N_Selected_Component) then
10707          Pref := Prefix (N);
10708
10709          --  If prefix is access type, then it is the designated object that is
10710          --  being modified, which means we have no entity to set the flag on.
10711
10712          if No (Etype (Pref)) or else Is_Access_Type (Etype (Pref)) then
10713             return;
10714
10715             --  Otherwise chase the prefix
10716
10717          else
10718             Set_Referenced_Modified (Pref, Out_Param);
10719          end if;
10720
10721       --  Otherwise see if we have an entity name (only other case to process)
10722
10723       elsif Is_Entity_Name (N) and then Present (Entity (N)) then
10724          Set_Referenced_As_LHS           (Entity (N), not Out_Param);
10725          Set_Referenced_As_Out_Parameter (Entity (N), Out_Param);
10726       end if;
10727    end Set_Referenced_Modified;
10728
10729    ----------------------------
10730    -- Set_Scope_Is_Transient --
10731    ----------------------------
10732
10733    procedure Set_Scope_Is_Transient (V : Boolean := True) is
10734    begin
10735       Scope_Stack.Table (Scope_Stack.Last).Is_Transient := V;
10736    end Set_Scope_Is_Transient;
10737
10738    -------------------
10739    -- Set_Size_Info --
10740    -------------------
10741
10742    procedure Set_Size_Info (T1, T2 : Entity_Id) is
10743    begin
10744       --  We copy Esize, but not RM_Size, since in general RM_Size is
10745       --  subtype specific and does not get inherited by all subtypes.
10746
10747       Set_Esize                     (T1, Esize                     (T2));
10748       Set_Has_Biased_Representation (T1, Has_Biased_Representation (T2));
10749
10750       if Is_Discrete_Or_Fixed_Point_Type (T1)
10751            and then
10752          Is_Discrete_Or_Fixed_Point_Type (T2)
10753       then
10754          Set_Is_Unsigned_Type       (T1, Is_Unsigned_Type          (T2));
10755       end if;
10756
10757       Set_Alignment                 (T1, Alignment                 (T2));
10758    end Set_Size_Info;
10759
10760    --------------------
10761    -- Static_Integer --
10762    --------------------
10763
10764    function Static_Integer (N : Node_Id) return Uint is
10765    begin
10766       Analyze_And_Resolve (N, Any_Integer);
10767
10768       if N = Error
10769         or else Error_Posted (N)
10770         or else Etype (N) = Any_Type
10771       then
10772          return No_Uint;
10773       end if;
10774
10775       if Is_Static_Expression (N) then
10776          if not Raises_Constraint_Error (N) then
10777             return Expr_Value (N);
10778          else
10779             return No_Uint;
10780          end if;
10781
10782       elsif Etype (N) = Any_Type then
10783          return No_Uint;
10784
10785       else
10786          Flag_Non_Static_Expr
10787            ("static integer expression required here", N);
10788          return No_Uint;
10789       end if;
10790    end Static_Integer;
10791
10792    --------------------------
10793    -- Statically_Different --
10794    --------------------------
10795
10796    function Statically_Different (E1, E2 : Node_Id) return Boolean is
10797       R1 : constant Node_Id := Get_Referenced_Object (E1);
10798       R2 : constant Node_Id := Get_Referenced_Object (E2);
10799    begin
10800       return     Is_Entity_Name (R1)
10801         and then Is_Entity_Name (R2)
10802         and then Entity (R1) /= Entity (R2)
10803         and then not Is_Formal (Entity (R1))
10804         and then not Is_Formal (Entity (R2));
10805    end Statically_Different;
10806
10807    -----------------------------
10808    -- Subprogram_Access_Level --
10809    -----------------------------
10810
10811    function Subprogram_Access_Level (Subp : Entity_Id) return Uint is
10812    begin
10813       if Present (Alias (Subp)) then
10814          return Subprogram_Access_Level (Alias (Subp));
10815       else
10816          return Scope_Depth (Enclosing_Dynamic_Scope (Subp));
10817       end if;
10818    end Subprogram_Access_Level;
10819
10820    -----------------
10821    -- Trace_Scope --
10822    -----------------
10823
10824    procedure Trace_Scope (N : Node_Id; E : Entity_Id; Msg : String) is
10825    begin
10826       if Debug_Flag_W then
10827          for J in 0 .. Scope_Stack.Last loop
10828             Write_Str ("  ");
10829          end loop;
10830
10831          Write_Str (Msg);
10832          Write_Name (Chars (E));
10833          Write_Str (" from ");
10834          Write_Location (Sloc (N));
10835          Write_Eol;
10836       end if;
10837    end Trace_Scope;
10838
10839    -----------------------
10840    -- Transfer_Entities --
10841    -----------------------
10842
10843    procedure Transfer_Entities (From : Entity_Id; To : Entity_Id) is
10844       Ent : Entity_Id := First_Entity (From);
10845
10846    begin
10847       if No (Ent) then
10848          return;
10849       end if;
10850
10851       if (Last_Entity (To)) = Empty then
10852          Set_First_Entity (To, Ent);
10853       else
10854          Set_Next_Entity (Last_Entity (To), Ent);
10855       end if;
10856
10857       Set_Last_Entity (To, Last_Entity (From));
10858
10859       while Present (Ent) loop
10860          Set_Scope (Ent, To);
10861
10862          if not Is_Public (Ent) then
10863             Set_Public_Status (Ent);
10864
10865             if Is_Public (Ent)
10866               and then Ekind (Ent) = E_Record_Subtype
10867
10868             then
10869                --  The components of the propagated Itype must be public
10870                --  as well.
10871
10872                declare
10873                   Comp : Entity_Id;
10874                begin
10875                   Comp := First_Entity (Ent);
10876                   while Present (Comp) loop
10877                      Set_Is_Public (Comp);
10878                      Next_Entity (Comp);
10879                   end loop;
10880                end;
10881             end if;
10882          end if;
10883
10884          Next_Entity (Ent);
10885       end loop;
10886
10887       Set_First_Entity (From, Empty);
10888       Set_Last_Entity (From, Empty);
10889    end Transfer_Entities;
10890
10891    -----------------------
10892    -- Type_Access_Level --
10893    -----------------------
10894
10895    function Type_Access_Level (Typ : Entity_Id) return Uint is
10896       Btyp : Entity_Id;
10897
10898    begin
10899       Btyp := Base_Type (Typ);
10900
10901       --  Ada 2005 (AI-230): For most cases of anonymous access types, we
10902       --  simply use the level where the type is declared. This is true for
10903       --  stand-alone object declarations, and for anonymous access types
10904       --  associated with components the level is the same as that of the
10905       --  enclosing composite type. However, special treatment is needed for
10906       --  the cases of access parameters, return objects of an anonymous access
10907       --  type, and, in Ada 95, access discriminants of limited types.
10908
10909       if Ekind (Btyp) in Access_Kind then
10910          if Ekind (Btyp) = E_Anonymous_Access_Type then
10911
10912             --  If the type is a nonlocal anonymous access type (such as for
10913             --  an access parameter) we treat it as being declared at the
10914             --  library level to ensure that names such as X.all'access don't
10915             --  fail static accessibility checks.
10916
10917             if not Is_Local_Anonymous_Access (Typ) then
10918                return Scope_Depth (Standard_Standard);
10919
10920             --  If this is a return object, the accessibility level is that of
10921             --  the result subtype of the enclosing function. The test here is
10922             --  little complicated, because we have to account for extended
10923             --  return statements that have been rewritten as blocks, in which
10924             --  case we have to find and the Is_Return_Object attribute of the
10925             --  itype's associated object. It would be nice to find a way to
10926             --  simplify this test, but it doesn't seem worthwhile to add a new
10927             --  flag just for purposes of this test. ???
10928
10929             elsif Ekind (Scope (Btyp)) = E_Return_Statement
10930               or else
10931                 (Is_Itype (Btyp)
10932                   and then Nkind (Associated_Node_For_Itype (Btyp)) =
10933                              N_Object_Declaration
10934                   and then Is_Return_Object
10935                              (Defining_Identifier
10936                                 (Associated_Node_For_Itype (Btyp))))
10937             then
10938                declare
10939                   Scop : Entity_Id;
10940
10941                begin
10942                   Scop := Scope (Scope (Btyp));
10943                   while Present (Scop) loop
10944                      exit when Ekind (Scop) = E_Function;
10945                      Scop := Scope (Scop);
10946                   end loop;
10947
10948                   --  Treat the return object's type as having the level of the
10949                   --  function's result subtype (as per RM05-6.5(5.3/2)).
10950
10951                   return Type_Access_Level (Etype (Scop));
10952                end;
10953             end if;
10954          end if;
10955
10956          Btyp := Root_Type (Btyp);
10957
10958          --  The accessibility level of anonymous access types associated with
10959          --  discriminants is that of the current instance of the type, and
10960          --  that's deeper than the type itself (AARM 3.10.2 (12.3.21)).
10961
10962          --  AI-402: access discriminants have accessibility based on the
10963          --  object rather than the type in Ada 2005, so the above paragraph
10964          --  doesn't apply.
10965
10966          --  ??? Needs completion with rules from AI-416
10967
10968          if Ada_Version <= Ada_95
10969            and then Ekind (Typ) = E_Anonymous_Access_Type
10970            and then Present (Associated_Node_For_Itype (Typ))
10971            and then Nkind (Associated_Node_For_Itype (Typ)) =
10972                                                  N_Discriminant_Specification
10973          then
10974             return Scope_Depth (Enclosing_Dynamic_Scope (Btyp)) + 1;
10975          end if;
10976       end if;
10977
10978       return Scope_Depth (Enclosing_Dynamic_Scope (Btyp));
10979    end Type_Access_Level;
10980
10981    --------------------
10982    -- Ultimate_Alias --
10983    --------------------
10984    --  To do: add occurrences calling this new subprogram
10985
10986    function Ultimate_Alias (Prim : Entity_Id) return Entity_Id is
10987       E : Entity_Id := Prim;
10988
10989    begin
10990       while Present (Alias (E)) loop
10991          E := Alias (E);
10992       end loop;
10993
10994       return E;
10995    end Ultimate_Alias;
10996
10997    --------------------------
10998    -- Unit_Declaration_Node --
10999    --------------------------
11000
11001    function Unit_Declaration_Node (Unit_Id : Entity_Id) return Node_Id is
11002       N : Node_Id := Parent (Unit_Id);
11003
11004    begin
11005       --  Predefined operators do not have a full function declaration
11006
11007       if Ekind (Unit_Id) = E_Operator then
11008          return N;
11009       end if;
11010
11011       --  Isn't there some better way to express the following ???
11012
11013       while Nkind (N) /= N_Abstract_Subprogram_Declaration
11014         and then Nkind (N) /= N_Formal_Package_Declaration
11015         and then Nkind (N) /= N_Function_Instantiation
11016         and then Nkind (N) /= N_Generic_Package_Declaration
11017         and then Nkind (N) /= N_Generic_Subprogram_Declaration
11018         and then Nkind (N) /= N_Package_Declaration
11019         and then Nkind (N) /= N_Package_Body
11020         and then Nkind (N) /= N_Package_Instantiation
11021         and then Nkind (N) /= N_Package_Renaming_Declaration
11022         and then Nkind (N) /= N_Procedure_Instantiation
11023         and then Nkind (N) /= N_Protected_Body
11024         and then Nkind (N) /= N_Subprogram_Declaration
11025         and then Nkind (N) /= N_Subprogram_Body
11026         and then Nkind (N) /= N_Subprogram_Body_Stub
11027         and then Nkind (N) /= N_Subprogram_Renaming_Declaration
11028         and then Nkind (N) /= N_Task_Body
11029         and then Nkind (N) /= N_Task_Type_Declaration
11030         and then Nkind (N) not in N_Formal_Subprogram_Declaration
11031         and then Nkind (N) not in N_Generic_Renaming_Declaration
11032       loop
11033          N := Parent (N);
11034          pragma Assert (Present (N));
11035       end loop;
11036
11037       return N;
11038    end Unit_Declaration_Node;
11039
11040    ------------------------------
11041    -- Universal_Interpretation --
11042    ------------------------------
11043
11044    function Universal_Interpretation (Opnd : Node_Id) return Entity_Id is
11045       Index : Interp_Index;
11046       It    : Interp;
11047
11048    begin
11049       --  The argument may be a formal parameter of an operator or subprogram
11050       --  with multiple interpretations, or else an expression for an actual.
11051
11052       if Nkind (Opnd) = N_Defining_Identifier
11053         or else not Is_Overloaded (Opnd)
11054       then
11055          if Etype (Opnd) = Universal_Integer
11056            or else Etype (Opnd) = Universal_Real
11057          then
11058             return Etype (Opnd);
11059          else
11060             return Empty;
11061          end if;
11062
11063       else
11064          Get_First_Interp (Opnd, Index, It);
11065          while Present (It.Typ) loop
11066             if It.Typ = Universal_Integer
11067               or else It.Typ = Universal_Real
11068             then
11069                return It.Typ;
11070             end if;
11071
11072             Get_Next_Interp (Index, It);
11073          end loop;
11074
11075          return Empty;
11076       end if;
11077    end Universal_Interpretation;
11078
11079    ---------------
11080    -- Unqualify --
11081    ---------------
11082
11083    function Unqualify (Expr : Node_Id) return Node_Id is
11084    begin
11085       --  Recurse to handle unlikely case of multiple levels of qualification
11086
11087       if Nkind (Expr) = N_Qualified_Expression then
11088          return Unqualify (Expression (Expr));
11089
11090       --  Normal case, not a qualified expression
11091
11092       else
11093          return Expr;
11094       end if;
11095    end Unqualify;
11096
11097    ----------------------
11098    -- Within_Init_Proc --
11099    ----------------------
11100
11101    function Within_Init_Proc return Boolean is
11102       S : Entity_Id;
11103
11104    begin
11105       S := Current_Scope;
11106       while not Is_Overloadable (S) loop
11107          if S = Standard_Standard then
11108             return False;
11109          else
11110             S := Scope (S);
11111          end if;
11112       end loop;
11113
11114       return Is_Init_Proc (S);
11115    end Within_Init_Proc;
11116
11117    ----------------
11118    -- Wrong_Type --
11119    ----------------
11120
11121    procedure Wrong_Type (Expr : Node_Id; Expected_Type : Entity_Id) is
11122       Found_Type : constant Entity_Id := First_Subtype (Etype (Expr));
11123       Expec_Type : constant Entity_Id := First_Subtype (Expected_Type);
11124
11125       function Has_One_Matching_Field return Boolean;
11126       --  Determines if Expec_Type is a record type with a single component or
11127       --  discriminant whose type matches the found type or is one dimensional
11128       --  array whose component type matches the found type.
11129
11130       ----------------------------
11131       -- Has_One_Matching_Field --
11132       ----------------------------
11133
11134       function Has_One_Matching_Field return Boolean is
11135          E : Entity_Id;
11136
11137       begin
11138          if Is_Array_Type (Expec_Type)
11139            and then Number_Dimensions (Expec_Type) = 1
11140            and then
11141              Covers (Etype (Component_Type (Expec_Type)), Found_Type)
11142          then
11143             return True;
11144
11145          elsif not Is_Record_Type (Expec_Type) then
11146             return False;
11147
11148          else
11149             E := First_Entity (Expec_Type);
11150             loop
11151                if No (E) then
11152                   return False;
11153
11154                elsif (Ekind (E) /= E_Discriminant
11155                        and then Ekind (E) /= E_Component)
11156                  or else (Chars (E) = Name_uTag
11157                            or else Chars (E) = Name_uParent)
11158                then
11159                   Next_Entity (E);
11160
11161                else
11162                   exit;
11163                end if;
11164             end loop;
11165
11166             if not Covers (Etype (E), Found_Type) then
11167                return False;
11168
11169             elsif Present (Next_Entity (E)) then
11170                return False;
11171
11172             else
11173                return True;
11174             end if;
11175          end if;
11176       end Has_One_Matching_Field;
11177
11178    --  Start of processing for Wrong_Type
11179
11180    begin
11181       --  Don't output message if either type is Any_Type, or if a message
11182       --  has already been posted for this node. We need to do the latter
11183       --  check explicitly (it is ordinarily done in Errout), because we
11184       --  are using ! to force the output of the error messages.
11185
11186       if Expec_Type = Any_Type
11187         or else Found_Type = Any_Type
11188         or else Error_Posted (Expr)
11189       then
11190          return;
11191
11192       --  In  an instance, there is an ongoing problem with completion of
11193       --  type derived from private types. Their structure is what Gigi
11194       --  expects, but the  Etype is the parent type rather than the
11195       --  derived private type itself. Do not flag error in this case. The
11196       --  private completion is an entity without a parent, like an Itype.
11197       --  Similarly, full and partial views may be incorrect in the instance.
11198       --  There is no simple way to insure that it is consistent ???
11199
11200       elsif In_Instance then
11201          if Etype (Etype (Expr)) = Etype (Expected_Type)
11202            and then
11203              (Has_Private_Declaration (Expected_Type)
11204                or else Has_Private_Declaration (Etype (Expr)))
11205            and then No (Parent (Expected_Type))
11206          then
11207             return;
11208          end if;
11209       end if;
11210
11211       --  An interesting special check. If the expression is parenthesized
11212       --  and its type corresponds to the type of the sole component of the
11213       --  expected record type, or to the component type of the expected one
11214       --  dimensional array type, then assume we have a bad aggregate attempt.
11215
11216       if Nkind (Expr) in N_Subexpr
11217         and then Paren_Count (Expr) /= 0
11218         and then Has_One_Matching_Field
11219       then
11220          Error_Msg_N ("positional aggregate cannot have one component", Expr);
11221
11222       --  Another special check, if we are looking for a pool-specific access
11223       --  type and we found an E_Access_Attribute_Type, then we have the case
11224       --  of an Access attribute being used in a context which needs a pool-
11225       --  specific type, which is never allowed. The one extra check we make
11226       --  is that the expected designated type covers the Found_Type.
11227
11228       elsif Is_Access_Type (Expec_Type)
11229         and then Ekind (Found_Type) = E_Access_Attribute_Type
11230         and then Ekind (Base_Type (Expec_Type)) /= E_General_Access_Type
11231         and then Ekind (Base_Type (Expec_Type)) /= E_Anonymous_Access_Type
11232         and then Covers
11233           (Designated_Type (Expec_Type), Designated_Type (Found_Type))
11234       then
11235          Error_Msg_N ("result must be general access type!", Expr);
11236          Error_Msg_NE ("add ALL to }!", Expr, Expec_Type);
11237
11238       --  Another special check, if the expected type is an integer type,
11239       --  but the expression is of type System.Address, and the parent is
11240       --  an addition or subtraction operation whose left operand is the
11241       --  expression in question and whose right operand is of an integral
11242       --  type, then this is an attempt at address arithmetic, so give
11243       --  appropriate message.
11244
11245       elsif Is_Integer_Type (Expec_Type)
11246         and then Is_RTE (Found_Type, RE_Address)
11247         and then (Nkind (Parent (Expr)) = N_Op_Add
11248                     or else
11249                   Nkind (Parent (Expr)) = N_Op_Subtract)
11250         and then Expr = Left_Opnd (Parent (Expr))
11251         and then Is_Integer_Type (Etype (Right_Opnd (Parent (Expr))))
11252       then
11253          Error_Msg_N
11254            ("address arithmetic not predefined in package System",
11255             Parent (Expr));
11256          Error_Msg_N
11257            ("\possible missing with/use of System.Storage_Elements",
11258             Parent (Expr));
11259          return;
11260
11261       --  If the expected type is an anonymous access type, as for access
11262       --  parameters and discriminants, the error is on the designated types.
11263
11264       elsif Ekind (Expec_Type) = E_Anonymous_Access_Type then
11265          if Comes_From_Source (Expec_Type) then
11266             Error_Msg_NE ("expected}!", Expr, Expec_Type);
11267          else
11268             Error_Msg_NE
11269               ("expected an access type with designated}",
11270                  Expr, Designated_Type (Expec_Type));
11271          end if;
11272
11273          if Is_Access_Type (Found_Type)
11274            and then not Comes_From_Source (Found_Type)
11275          then
11276             Error_Msg_NE
11277               ("\\found an access type with designated}!",
11278                 Expr, Designated_Type (Found_Type));
11279          else
11280             if From_With_Type (Found_Type) then
11281                Error_Msg_NE ("\\found incomplete}!", Expr, Found_Type);
11282                Error_Msg_Qual_Level := 99;
11283                Error_Msg_NE ("\\missing `WITH &;", Expr, Scope (Found_Type));
11284                Error_Msg_Qual_Level := 0;
11285             else
11286                Error_Msg_NE ("found}!", Expr, Found_Type);
11287             end if;
11288          end if;
11289
11290       --  Normal case of one type found, some other type expected
11291
11292       else
11293          --  If the names of the two types are the same, see if some number
11294          --  of levels of qualification will help. Don't try more than three
11295          --  levels, and if we get to standard, it's no use (and probably
11296          --  represents an error in the compiler) Also do not bother with
11297          --  internal scope names.
11298
11299          declare
11300             Expec_Scope : Entity_Id;
11301             Found_Scope : Entity_Id;
11302
11303          begin
11304             Expec_Scope := Expec_Type;
11305             Found_Scope := Found_Type;
11306
11307             for Levels in Int range 0 .. 3 loop
11308                if Chars (Expec_Scope) /= Chars (Found_Scope) then
11309                   Error_Msg_Qual_Level := Levels;
11310                   exit;
11311                end if;
11312
11313                Expec_Scope := Scope (Expec_Scope);
11314                Found_Scope := Scope (Found_Scope);
11315
11316                exit when Expec_Scope = Standard_Standard
11317                  or else Found_Scope = Standard_Standard
11318                  or else not Comes_From_Source (Expec_Scope)
11319                  or else not Comes_From_Source (Found_Scope);
11320             end loop;
11321          end;
11322
11323          if Is_Record_Type (Expec_Type)
11324            and then Present (Corresponding_Remote_Type (Expec_Type))
11325          then
11326             Error_Msg_NE ("expected}!", Expr,
11327                           Corresponding_Remote_Type (Expec_Type));
11328          else
11329             Error_Msg_NE ("expected}!", Expr, Expec_Type);
11330          end if;
11331
11332          if Is_Entity_Name (Expr)
11333            and then Is_Package_Or_Generic_Package (Entity (Expr))
11334          then
11335             Error_Msg_N ("\\found package name!", Expr);
11336
11337          elsif Is_Entity_Name (Expr)
11338            and then
11339              (Ekind (Entity (Expr)) = E_Procedure
11340                 or else
11341               Ekind (Entity (Expr)) = E_Generic_Procedure)
11342          then
11343             if Ekind (Expec_Type) = E_Access_Subprogram_Type then
11344                Error_Msg_N
11345                  ("found procedure name, possibly missing Access attribute!",
11346                    Expr);
11347             else
11348                Error_Msg_N
11349                  ("\\found procedure name instead of function!", Expr);
11350             end if;
11351
11352          elsif Nkind (Expr) = N_Function_Call
11353            and then Ekind (Expec_Type) = E_Access_Subprogram_Type
11354            and then Etype (Designated_Type (Expec_Type)) = Etype (Expr)
11355            and then No (Parameter_Associations (Expr))
11356          then
11357             Error_Msg_N
11358               ("found function name, possibly missing Access attribute!",
11359                Expr);
11360
11361          --  Catch common error: a prefix or infix operator which is not
11362          --  directly visible because the type isn't.
11363
11364          elsif Nkind (Expr) in N_Op
11365             and then Is_Overloaded (Expr)
11366             and then not Is_Immediately_Visible (Expec_Type)
11367             and then not Is_Potentially_Use_Visible (Expec_Type)
11368             and then not In_Use (Expec_Type)
11369             and then Has_Compatible_Type (Right_Opnd (Expr), Expec_Type)
11370          then
11371             Error_Msg_N
11372               ("operator of the type is not directly visible!", Expr);
11373
11374          elsif Ekind (Found_Type) = E_Void
11375            and then Present (Parent (Found_Type))
11376            and then Nkind (Parent (Found_Type)) = N_Full_Type_Declaration
11377          then
11378             Error_Msg_NE ("\\found premature usage of}!", Expr, Found_Type);
11379
11380          else
11381             Error_Msg_NE ("\\found}!", Expr, Found_Type);
11382          end if;
11383
11384          --  A special check for cases like M1 and M2 = 0 where M1 and M2 are
11385          --  of the same modular type, and (M1 and M2) = 0 was intended.
11386
11387          if Expec_Type = Standard_Boolean
11388            and then Is_Modular_Integer_Type (Found_Type)
11389            and then Nkind_In (Parent (Expr), N_Op_And, N_Op_Or, N_Op_Xor)
11390            and then Nkind (Right_Opnd (Parent (Expr))) in N_Op_Compare
11391          then
11392             declare
11393                Op : constant Node_Id := Right_Opnd (Parent (Expr));
11394                L  : constant Node_Id := Left_Opnd (Op);
11395                R  : constant Node_Id := Right_Opnd (Op);
11396             begin
11397                --  The case for the message is when the left operand of the
11398                --  comparison is the same modular type, or when it is an
11399                --  integer literal (or other universal integer expression),
11400                --  which would have been typed as the modular type if the
11401                --  parens had been there.
11402
11403                if (Etype (L) = Found_Type
11404                      or else
11405                    Etype (L) = Universal_Integer)
11406                  and then Is_Integer_Type (Etype (R))
11407                then
11408                   Error_Msg_N
11409                     ("\\possible missing parens for modular operation", Expr);
11410                end if;
11411             end;
11412          end if;
11413
11414          --  Reset error message qualification indication
11415
11416          Error_Msg_Qual_Level := 0;
11417       end if;
11418    end Wrong_Type;
11419
11420 end Sem_Util;