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 := Make_Temporary (Loc, 'S');
 402       Set_Is_Internal (Subt);
 403
 404       Decl :=
 405         Make_Subtype_Declaration (Loc,
 406           Defining_Identifier => Subt,
 407           Subtype_Indication =>
 408             Make_Subtype_Indication (Loc,
 409               Subtype_Mark => New_Reference_To (T,  Loc),
 410               Constraint  =>
 411                 Make_Index_Or_Discriminant_Constraint (Loc,
 412                   Constraints => Constraints)));
 413
 414       Mark_Rewrite_Insertion (Decl);
 415       return Decl;
 416    end Build_Actual_Subtype;
 417
 418    ---------------------------------------
 419    -- Build_Actual_Subtype_Of_Component --
 420    ---------------------------------------
 421
 422    function Build_Actual_Subtype_Of_Component
 423      (T : Entity_Id;
 424       N : Node_Id) return Node_Id
 425    is
 426       Loc       : constant Source_Ptr := Sloc (N);
 427       P         : constant Node_Id    := Prefix (N);
 428       D         : Elmt_Id;
 429       Id        : Node_Id;
 430       Indx_Type : Entity_Id;
 431
 432       Deaccessed_T : Entity_Id;
 433       --  This is either a copy of T, or if T is an access type, then it is
 434       --  the directly designated type of this access type.
 435
 436       function Build_Actual_Array_Constraint return List_Id;
 437       --  If one or more of the bounds of the component depends on
 438       --  discriminants, build  actual constraint using the discriminants
 439       --  of the prefix.
 440
 441       function Build_Actual_Record_Constraint return List_Id;
 442       --  Similar to previous one, for discriminated components constrained
 443       --  by the discriminant of the enclosing object.
 444
 445       -----------------------------------
 446       -- Build_Actual_Array_Constraint --
 447       -----------------------------------
 448
 449       function Build_Actual_Array_Constraint return List_Id is
 450          Constraints : constant List_Id := New_List;
 451          Indx        : Node_Id;
 452          Hi          : Node_Id;
 453          Lo          : Node_Id;
 454          Old_Hi      : Node_Id;
 455          Old_Lo      : Node_Id;
 456
 457       begin
 458          Indx := First_Index (Deaccessed_T);
 459          while Present (Indx) loop
 460             Old_Lo := Type_Low_Bound  (Etype (Indx));
 461             Old_Hi := Type_High_Bound (Etype (Indx));
 462
 463             if Denotes_Discriminant (Old_Lo) then
 464                Lo :=
 465                  Make_Selected_Component (Loc,
 466                    Prefix => New_Copy_Tree (P),
 467                    Selector_Name => New_Occurrence_Of (Entity (Old_Lo), Loc));
 468
 469             else
 470                Lo := New_Copy_Tree (Old_Lo);
 471
 472                --  The new bound will be reanalyzed in the enclosing
 473                --  declaration. For literal bounds that come from a type
 474                --  declaration, the type of the context must be imposed, so
 475                --  insure that analysis will take place. For non-universal
 476                --  types this is not strictly necessary.
 477
 478                Set_Analyzed (Lo, False);
 479             end if;
 480
 481             if Denotes_Discriminant (Old_Hi) then
 482                Hi :=
 483                  Make_Selected_Component (Loc,
 484                    Prefix => New_Copy_Tree (P),
 485                    Selector_Name => New_Occurrence_Of (Entity (Old_Hi), Loc));
 486
 487             else
 488                Hi := New_Copy_Tree (Old_Hi);
 489                Set_Analyzed (Hi, False);
 490             end if;
 491
 492             Append (Make_Range (Loc, Lo, Hi), Constraints);
 493             Next_Index (Indx);
 494          end loop;
 495
 496          return Constraints;
 497       end Build_Actual_Array_Constraint;
 498
 499       ------------------------------------
 500       -- Build_Actual_Record_Constraint --
 501       ------------------------------------
 502
 503       function Build_Actual_Record_Constraint return List_Id is
 504          Constraints : constant List_Id := New_List;
 505          D           : Elmt_Id;
 506          D_Val       : Node_Id;
 507
 508       begin
 509          D := First_Elmt (Discriminant_Constraint (Deaccessed_T));
 510          while Present (D) loop
 511             if Denotes_Discriminant (Node (D)) then
 512                D_Val :=  Make_Selected_Component (Loc,
 513                  Prefix => New_Copy_Tree (P),
 514                 Selector_Name => New_Occurrence_Of (Entity (Node (D)), Loc));
 515
 516             else
 517                D_Val := New_Copy_Tree (Node (D));
 518             end if;
 519
 520             Append (D_Val, Constraints);
 521             Next_Elmt (D);
 522          end loop;
 523
 524          return Constraints;
 525       end Build_Actual_Record_Constraint;
 526
 527    --  Start of processing for Build_Actual_Subtype_Of_Component
 528
 529    begin
 530       --  Why the test for Spec_Expression mode here???
 531
 532       if In_Spec_Expression then
 533          return Empty;
 534
 535       --  More comments for the rest of this body would be good ???
 536
 537       elsif Nkind (N) = N_Explicit_Dereference then
 538          if Is_Composite_Type (T)
 539            and then not Is_Constrained (T)
 540            and then not (Is_Class_Wide_Type (T)
 541                           and then Is_Constrained (Root_Type (T)))
 542            and then not Has_Unknown_Discriminants (T)
 543          then
 544             --  If the type of the dereference is already constrained, it is an
 545             --  actual subtype.
 546
 547             if Is_Array_Type (Etype (N))
 548               and then Is_Constrained (Etype (N))
 549             then
 550                return Empty;
 551             else
 552                Remove_Side_Effects (P);
 553                return Build_Actual_Subtype (T, N);
 554             end if;
 555          else
 556             return Empty;
 557          end if;
 558       end if;
 559
 560       if Ekind (T) = E_Access_Subtype then
 561          Deaccessed_T := Designated_Type (T);
 562       else
 563          Deaccessed_T := T;
 564       end if;
 565
 566       if Ekind (Deaccessed_T) = E_Array_Subtype then
 567          Id := First_Index (Deaccessed_T);
 568          while Present (Id) loop
 569             Indx_Type := Underlying_Type (Etype (Id));
 570
 571             if Denotes_Discriminant (Type_Low_Bound  (Indx_Type))
 572                  or else
 573                Denotes_Discriminant (Type_High_Bound (Indx_Type))
 574             then
 575                Remove_Side_Effects (P);
 576                return
 577                  Build_Component_Subtype
 578                    (Build_Actual_Array_Constraint, Loc, Base_Type (T));
 579             end if;
 580
 581             Next_Index (Id);
 582          end loop;
 583
 584       elsif Is_Composite_Type (Deaccessed_T)
 585         and then Has_Discriminants (Deaccessed_T)
 586         and then not Has_Unknown_Discriminants (Deaccessed_T)
 587       then
 588          D := First_Elmt (Discriminant_Constraint (Deaccessed_T));
 589          while Present (D) loop
 590             if Denotes_Discriminant (Node (D)) then
 591                Remove_Side_Effects (P);
 592                return
 593                  Build_Component_Subtype (
 594                    Build_Actual_Record_Constraint, Loc, Base_Type (T));
 595             end if;
 596
 597             Next_Elmt (D);
 598          end loop;
 599       end if;
 600
 601       --  If none of the above, the actual and nominal subtypes are the same
 602
 603       return Empty;
 604    end Build_Actual_Subtype_Of_Component;
 605
 606    -----------------------------
 607    -- Build_Component_Subtype --
 608    -----------------------------
 609
 610    function Build_Component_Subtype
 611      (C   : List_Id;
 612       Loc : Source_Ptr;
 613       T   : Entity_Id) return Node_Id
 614    is
 615       Subt : Entity_Id;
 616       Decl : Node_Id;
 617
 618    begin
 619       --  Unchecked_Union components do not require component subtypes
 620
 621       if Is_Unchecked_Union (T) then
 622          return Empty;
 623       end if;
 624
 625       Subt := Make_Temporary (Loc, 'S');
 626       Set_Is_Internal (Subt);
 627
 628       Decl :=
 629         Make_Subtype_Declaration (Loc,
 630           Defining_Identifier => Subt,
 631           Subtype_Indication =>
 632             Make_Subtype_Indication (Loc,
 633               Subtype_Mark => New_Reference_To (Base_Type (T),  Loc),
 634               Constraint  =>
 635                 Make_Index_Or_Discriminant_Constraint (Loc,
 636                   Constraints => C)));
 637
 638       Mark_Rewrite_Insertion (Decl);
 639       return Decl;
 640    end Build_Component_Subtype;
 641
 642    ---------------------------
 643    -- Build_Default_Subtype --
 644    ---------------------------
 645
 646    function Build_Default_Subtype
 647      (T : Entity_Id;
 648       N : Node_Id) return Entity_Id
 649    is
 650       Loc  : constant Source_Ptr := Sloc (N);
 651       Disc : Entity_Id;
 652
 653    begin
 654       if not Has_Discriminants (T) or else Is_Constrained (T) then
 655          return T;
 656       end if;
 657
 658       Disc := First_Discriminant (T);
 659
 660       if No (Discriminant_Default_Value (Disc)) then
 661          return T;
 662       end if;
 663
 664       declare
 665          Act         : constant Entity_Id := Make_Temporary (Loc, 'S');
 666          Constraints : constant List_Id := New_List;
 667          Decl        : Node_Id;
 668
 669       begin
 670          while Present (Disc) loop
 671             Append_To (Constraints,
 672               New_Copy_Tree (Discriminant_Default_Value (Disc)));
 673             Next_Discriminant (Disc);
 674          end loop;
 675
 676          Decl :=
 677            Make_Subtype_Declaration (Loc,
 678              Defining_Identifier => Act,
 679              Subtype_Indication =>
 680                Make_Subtype_Indication (Loc,
 681                  Subtype_Mark => New_Occurrence_Of (T, Loc),
 682                  Constraint =>
 683                    Make_Index_Or_Discriminant_Constraint (Loc,
 684                      Constraints => Constraints)));
 685
 686          Insert_Action (N, Decl);
 687          Analyze (Decl);
 688          return Act;
 689       end;
 690    end Build_Default_Subtype;
 691
 692    --------------------------------------------
 693    -- Build_Discriminal_Subtype_Of_Component --
 694    --------------------------------------------
 695
 696    function Build_Discriminal_Subtype_Of_Component
 697      (T : Entity_Id) return Node_Id
 698    is
 699       Loc : constant Source_Ptr := Sloc (T);
 700       D   : Elmt_Id;
 701       Id  : Node_Id;
 702
 703       function Build_Discriminal_Array_Constraint return List_Id;
 704       --  If one or more of the bounds of the component depends on
 705       --  discriminants, build  actual constraint using the discriminants
 706       --  of the prefix.
 707
 708       function Build_Discriminal_Record_Constraint return List_Id;
 709       --  Similar to previous one, for discriminated components constrained
 710       --  by the discriminant of the enclosing object.
 711
 712       ----------------------------------------
 713       -- Build_Discriminal_Array_Constraint --
 714       ----------------------------------------
 715
 716       function Build_Discriminal_Array_Constraint return List_Id is
 717          Constraints : constant List_Id := New_List;
 718          Indx        : Node_Id;
 719          Hi          : Node_Id;
 720          Lo          : Node_Id;
 721          Old_Hi      : Node_Id;
 722          Old_Lo      : Node_Id;
 723
 724       begin
 725          Indx := First_Index (T);
 726          while Present (Indx) loop
 727             Old_Lo := Type_Low_Bound  (Etype (Indx));
 728             Old_Hi := Type_High_Bound (Etype (Indx));
 729
 730             if Denotes_Discriminant (Old_Lo) then
 731                Lo := New_Occurrence_Of (Discriminal (Entity (Old_Lo)), Loc);
 732
 733             else
 734                Lo := New_Copy_Tree (Old_Lo);
 735             end if;
 736
 737             if Denotes_Discriminant (Old_Hi) then
 738                Hi := New_Occurrence_Of (Discriminal (Entity (Old_Hi)), Loc);
 739
 740             else
 741                Hi := New_Copy_Tree (Old_Hi);
 742             end if;
 743
 744             Append (Make_Range (Loc, Lo, Hi), Constraints);
 745             Next_Index (Indx);
 746          end loop;
 747
 748          return Constraints;
 749       end Build_Discriminal_Array_Constraint;
 750
 751       -----------------------------------------
 752       -- Build_Discriminal_Record_Constraint --
 753       -----------------------------------------
 754
 755       function Build_Discriminal_Record_Constraint return List_Id is
 756          Constraints : constant List_Id := New_List;
 757          D           : Elmt_Id;
 758          D_Val       : Node_Id;
 759
 760       begin
 761          D := First_Elmt (Discriminant_Constraint (T));
 762          while Present (D) loop
 763             if Denotes_Discriminant (Node (D)) then
 764                D_Val :=
 765                  New_Occurrence_Of (Discriminal (Entity (Node (D))), Loc);
 766
 767             else
 768                D_Val := New_Copy_Tree (Node (D));
 769             end if;
 770
 771             Append (D_Val, Constraints);
 772             Next_Elmt (D);
 773          end loop;
 774
 775          return Constraints;
 776       end Build_Discriminal_Record_Constraint;
 777
 778    --  Start of processing for Build_Discriminal_Subtype_Of_Component
 779
 780    begin
 781       if Ekind (T) = E_Array_Subtype then
 782          Id := First_Index (T);
 783          while Present (Id) loop
 784             if Denotes_Discriminant (Type_Low_Bound  (Etype (Id))) or else
 785                Denotes_Discriminant (Type_High_Bound (Etype (Id)))
 786             then
 787                return Build_Component_Subtype
 788                  (Build_Discriminal_Array_Constraint, Loc, T);
 789             end if;
 790
 791             Next_Index (Id);
 792          end loop;
 793
 794       elsif Ekind (T) = E_Record_Subtype
 795         and then Has_Discriminants (T)
 796         and then not Has_Unknown_Discriminants (T)
 797       then
 798          D := First_Elmt (Discriminant_Constraint (T));
 799          while Present (D) loop
 800             if Denotes_Discriminant (Node (D)) then
 801                return Build_Component_Subtype
 802                  (Build_Discriminal_Record_Constraint, Loc, T);
 803             end if;
 804
 805             Next_Elmt (D);
 806          end loop;
 807       end if;
 808
 809       --  If none of the above, the actual and nominal subtypes are the same
 810
 811       return Empty;
 812    end Build_Discriminal_Subtype_Of_Component;
 813
 814    ------------------------------
 815    -- Build_Elaboration_Entity --
 816    ------------------------------
 817
 818    procedure Build_Elaboration_Entity (N : Node_Id; Spec_Id : Entity_Id) is
 819       Loc      : constant Source_Ptr := Sloc (N);
 820       Decl     : Node_Id;
 821       Elab_Ent : Entity_Id;
 822
 823       procedure Set_Package_Name (Ent : Entity_Id);
 824       --  Given an entity, sets the fully qualified name of the entity in
 825       --  Name_Buffer, with components separated by double underscores. This
 826       --  is a recursive routine that climbs the scope chain to Standard.
 827
 828       ----------------------
 829       -- Set_Package_Name --
 830       ----------------------
 831
 832       procedure Set_Package_Name (Ent : Entity_Id) is
 833       begin
 834          if Scope (Ent) /= Standard_Standard then
 835             Set_Package_Name (Scope (Ent));
 836
 837             declare
 838                Nam : constant String := Get_Name_String (Chars (Ent));
 839             begin
 840                Name_Buffer (Name_Len + 1) := '_';
 841                Name_Buffer (Name_Len + 2) := '_';
 842                Name_Buffer (Name_Len + 3 .. Name_Len + Nam'Length + 2) := Nam;
 843                Name_Len := Name_Len + Nam'Length + 2;
 844             end;
 845
 846          else
 847             Get_Name_String (Chars (Ent));
 848          end if;
 849       end Set_Package_Name;
 850
 851    --  Start of processing for Build_Elaboration_Entity
 852
 853    begin
 854       --  Ignore if already constructed
 855
 856       if Present (Elaboration_Entity (Spec_Id)) then
 857          return;
 858       end if;
 859
 860       --  Construct name of elaboration entity as xxx_E, where xxx is the unit
 861       --  name with dots replaced by double underscore. We have to manually
 862       --  construct this name, since it will be elaborated in the outer scope,
 863       --  and thus will not have the unit name automatically prepended.
 864
 865       Set_Package_Name (Spec_Id);
 866
 867       --  Append _E
 868
 869       Name_Buffer (Name_Len + 1) := '_';
 870       Name_Buffer (Name_Len + 2) := 'E';
 871       Name_Len := Name_Len + 2;
 872
 873       --  Create elaboration flag
 874
 875       Elab_Ent :=
 876         Make_Defining_Identifier (Loc, Chars => Name_Find);
 877       Set_Elaboration_Entity (Spec_Id, Elab_Ent);
 878
 879       Decl :=
 880          Make_Object_Declaration (Loc,
 881            Defining_Identifier => Elab_Ent,
 882            Object_Definition   =>
 883              New_Occurrence_Of (Standard_Boolean, Loc),
 884            Expression          =>
 885              New_Occurrence_Of (Standard_False, Loc));
 886
 887       Push_Scope (Standard_Standard);
 888       Add_Global_Declaration (Decl);
 889       Pop_Scope;
 890
 891       --  Reset True_Constant indication, since we will indeed assign a value
 892       --  to the variable in the binder main. We also kill the Current_Value
 893       --  and Last_Assignment fields for the same reason.
 894
 895       Set_Is_True_Constant (Elab_Ent, False);
 896       Set_Current_Value    (Elab_Ent, Empty);
 897       Set_Last_Assignment  (Elab_Ent, Empty);
 898
 899       --  We do not want any further qualification of the name (if we did
 900       --  not do this, we would pick up the name of the generic package
 901       --  in the case of a library level generic instantiation).
 902
 903       Set_Has_Qualified_Name       (Elab_Ent);
 904       Set_Has_Fully_Qualified_Name (Elab_Ent);
 905    end Build_Elaboration_Entity;
 906
 907    -----------------------------------
 908    -- Cannot_Raise_Constraint_Error --
 909    -----------------------------------
 910
 911    function Cannot_Raise_Constraint_Error (Expr : Node_Id) return Boolean is
 912    begin
 913       if Compile_Time_Known_Value (Expr) then
 914          return True;
 915
 916       elsif Do_Range_Check (Expr) then
 917          return False;
 918
 919       elsif Raises_Constraint_Error (Expr) then
 920          return False;
 921
 922       else
 923          case Nkind (Expr) is
 924             when N_Identifier =>
 925                return True;
 926
 927             when N_Expanded_Name =>
 928                return True;
 929
 930             when N_Selected_Component =>
 931                return not Do_Discriminant_Check (Expr);
 932
 933             when N_Attribute_Reference =>
 934                if Do_Overflow_Check (Expr) then
 935                   return False;
 936
 937                elsif No (Expressions (Expr)) then
 938                   return True;
 939
 940                else
 941                   declare
 942                      N : Node_Id;
 943
 944                   begin
 945                      N := First (Expressions (Expr));
 946                      while Present (N) loop
 947                         if Cannot_Raise_Constraint_Error (N) then
 948                            Next (N);
 949                         else
 950                            return False;
 951                         end if;
 952                      end loop;
 953
 954                      return True;
 955                   end;
 956                end if;
 957
 958             when N_Type_Conversion =>
 959                if Do_Overflow_Check (Expr)
 960                  or else Do_Length_Check (Expr)
 961                  or else Do_Tag_Check (Expr)
 962                then
 963                   return False;
 964                else
 965                   return
 966                     Cannot_Raise_Constraint_Error (Expression (Expr));
 967                end if;
 968
 969             when N_Unchecked_Type_Conversion =>
 970                return Cannot_Raise_Constraint_Error (Expression (Expr));
 971
 972             when N_Unary_Op =>
 973                if Do_Overflow_Check (Expr) then
 974                   return False;
 975                else
 976                   return
 977                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
 978                end if;
 979
 980             when N_Op_Divide |
 981                  N_Op_Mod    |
 982                  N_Op_Rem
 983             =>
 984                if Do_Division_Check (Expr)
 985                  or else Do_Overflow_Check (Expr)
 986                then
 987                   return False;
 988                else
 989                   return
 990                     Cannot_Raise_Constraint_Error (Left_Opnd (Expr))
 991                       and then
 992                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
 993                end if;
 994
 995             when N_Op_Add                    |
 996                  N_Op_And                    |
 997                  N_Op_Concat                 |
 998                  N_Op_Eq                     |
 999                  N_Op_Expon                  |
1000                  N_Op_Ge                     |
1001                  N_Op_Gt                     |
1002                  N_Op_Le                     |
1003                  N_Op_Lt                     |
1004                  N_Op_Multiply               |
1005                  N_Op_Ne                     |
1006                  N_Op_Or                     |
1007                  N_Op_Rotate_Left            |
1008                  N_Op_Rotate_Right           |
1009                  N_Op_Shift_Left             |
1010                  N_Op_Shift_Right            |
1011                  N_Op_Shift_Right_Arithmetic |
1012                  N_Op_Subtract               |
1013                  N_Op_Xor
1014             =>
1015                if Do_Overflow_Check (Expr) then
1016                   return False;
1017                else
1018                   return
1019                     Cannot_Raise_Constraint_Error (Left_Opnd (Expr))
1020                       and then
1021                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
1022                end if;
1023
1024             when others =>
1025                return False;
1026          end case;
1027       end if;
1028    end Cannot_Raise_Constraint_Error;
1029
1030    -----------------------------------------
1031    -- Check_Dynamically_Tagged_Expression --
1032    -----------------------------------------
1033
1034    procedure Check_Dynamically_Tagged_Expression
1035      (Expr        : Node_Id;
1036       Typ         : Entity_Id;
1037       Related_Nod : Node_Id)
1038    is
1039    begin
1040       pragma Assert (Is_Tagged_Type (Typ));
1041
1042       --  In order to avoid spurious errors when analyzing the expanded code,
1043       --  this check is done only for nodes that come from source and for
1044       --  actuals of generic instantiations.
1045
1046       if (Comes_From_Source (Related_Nod)
1047            or else In_Generic_Actual (Expr))
1048         and then (Is_Class_Wide_Type (Etype (Expr))
1049                    or else Is_Dynamically_Tagged (Expr))
1050         and then Is_Tagged_Type (Typ)
1051         and then not Is_Class_Wide_Type (Typ)
1052       then
1053          Error_Msg_N ("dynamically tagged expression not allowed!", Expr);
1054       end if;
1055    end Check_Dynamically_Tagged_Expression;
1056
1057    --------------------------
1058    -- Check_Fully_Declared --
1059    --------------------------
1060
1061    procedure Check_Fully_Declared (T : Entity_Id; N : Node_Id) is
1062    begin
1063       if Ekind (T) = E_Incomplete_Type then
1064
1065          --  Ada 2005 (AI-50217): If the type is available through a limited
1066          --  with_clause, verify that its full view has been analyzed.
1067
1068          if From_With_Type (T)
1069            and then Present (Non_Limited_View (T))
1070            and then Ekind (Non_Limited_View (T)) /= E_Incomplete_Type
1071          then
1072             --  The non-limited view is fully declared
1073             null;
1074
1075          else
1076             Error_Msg_NE
1077               ("premature usage of incomplete}", N, First_Subtype (T));
1078          end if;
1079
1080       --  Need comments for these tests ???
1081
1082       elsif Has_Private_Component (T)
1083         and then not Is_Generic_Type (Root_Type (T))
1084         and then not In_Spec_Expression
1085       then
1086          --  Special case: if T is the anonymous type created for a single
1087          --  task or protected object, use the name of the source object.
1088
1089          if Is_Concurrent_Type (T)
1090            and then not Comes_From_Source (T)
1091            and then Nkind (N) = N_Object_Declaration
1092          then
1093             Error_Msg_NE ("type of& has incomplete component", N,
1094               Defining_Identifier (N));
1095
1096          else
1097             Error_Msg_NE
1098               ("premature usage of incomplete}", N, First_Subtype (T));
1099          end if;
1100       end if;
1101    end Check_Fully_Declared;
1102
1103    -------------------------
1104    -- Check_Nested_Access --
1105    -------------------------
1106
1107    procedure Check_Nested_Access (Ent : Entity_Id) is
1108       Scop         : constant Entity_Id := Current_Scope;
1109       Current_Subp : Entity_Id;
1110       Enclosing    : Entity_Id;
1111
1112    begin
1113       --  Currently only enabled for VM back-ends for efficiency, should we
1114       --  enable it more systematically ???
1115
1116       --  Check for Is_Imported needs commenting below ???
1117
1118       if VM_Target /= No_VM
1119         and then (Ekind (Ent) = E_Variable
1120                     or else
1121                   Ekind (Ent) = E_Constant
1122                     or else
1123                   Ekind (Ent) = E_Loop_Parameter)
1124         and then Scope (Ent) /= Empty
1125         and then not Is_Library_Level_Entity (Ent)
1126         and then not Is_Imported (Ent)
1127       then
1128          if Is_Subprogram (Scop)
1129            or else Is_Generic_Subprogram (Scop)
1130            or else Is_Entry (Scop)
1131          then
1132             Current_Subp := Scop;
1133          else
1134             Current_Subp := Current_Subprogram;
1135          end if;
1136
1137          Enclosing := Enclosing_Subprogram (Ent);
1138
1139          if Enclosing /= Empty
1140            and then Enclosing /= Current_Subp
1141          then
1142             Set_Has_Up_Level_Access (Ent, True);
1143          end if;
1144       end if;
1145    end Check_Nested_Access;
1146
1147    ------------------------------------------
1148    -- Check_Potentially_Blocking_Operation --
1149    ------------------------------------------
1150
1151    procedure Check_Potentially_Blocking_Operation (N : Node_Id) is
1152       S : Entity_Id;
1153    begin
1154       --  N is one of the potentially blocking operations listed in 9.5.1(8).
1155       --  When pragma Detect_Blocking is active, the run time will raise
1156       --  Program_Error. Here we only issue a warning, since we generally
1157       --  support the use of potentially blocking operations in the absence
1158       --  of the pragma.
1159
1160       --  Indirect blocking through a subprogram call cannot be diagnosed
1161       --  statically without interprocedural analysis, so we do not attempt
1162       --  to do it here.
1163
1164       S := Scope (Current_Scope);
1165       while Present (S) and then S /= Standard_Standard loop
1166          if Is_Protected_Type (S) then
1167             Error_Msg_N
1168               ("potentially blocking operation in protected operation?", N);
1169
1170             return;
1171          end if;
1172
1173          S := Scope (S);
1174       end loop;
1175    end Check_Potentially_Blocking_Operation;
1176
1177    ------------------------------
1178    -- Check_Unprotected_Access --
1179    ------------------------------
1180
1181    procedure Check_Unprotected_Access
1182      (Context : Node_Id;
1183       Expr    : Node_Id)
1184    is
1185       Cont_Encl_Typ : Entity_Id;
1186       Pref_Encl_Typ : Entity_Id;
1187
1188       function Enclosing_Protected_Type (Obj : Node_Id) return Entity_Id;
1189       --  Check whether Obj is a private component of a protected object.
1190       --  Return the protected type where the component resides, Empty
1191       --  otherwise.
1192
1193       function Is_Public_Operation return Boolean;
1194       --  Verify that the enclosing operation is callable from outside the
1195       --  protected object, to minimize false positives.
1196
1197       ------------------------------
1198       -- Enclosing_Protected_Type --
1199       ------------------------------
1200
1201       function Enclosing_Protected_Type (Obj : Node_Id) return Entity_Id is
1202       begin
1203          if Is_Entity_Name (Obj) then
1204             declare
1205                Ent : Entity_Id := Entity (Obj);
1206
1207             begin
1208                --  The object can be a renaming of a private component, use
1209                --  the original record component.
1210
1211                if Is_Prival (Ent) then
1212                   Ent := Prival_Link (Ent);
1213                end if;
1214
1215                if Is_Protected_Type (Scope (Ent)) then
1216                   return Scope (Ent);
1217                end if;
1218             end;
1219          end if;
1220
1221          --  For indexed and selected components, recursively check the prefix
1222
1223          if Nkind_In (Obj, N_Indexed_Component, N_Selected_Component) then
1224             return Enclosing_Protected_Type (Prefix (Obj));
1225
1226          --  The object does not denote a protected component
1227
1228          else
1229             return Empty;
1230          end if;
1231       end Enclosing_Protected_Type;
1232
1233       -------------------------
1234       -- Is_Public_Operation --
1235       -------------------------
1236
1237       function Is_Public_Operation return Boolean is
1238          S : Entity_Id;
1239          E : Entity_Id;
1240
1241       begin
1242          S := Current_Scope;
1243          while Present (S)
1244            and then S /= Pref_Encl_Typ
1245          loop
1246             if Scope (S) = Pref_Encl_Typ then
1247                E := First_Entity (Pref_Encl_Typ);
1248                while Present (E)
1249                  and then E /= First_Private_Entity (Pref_Encl_Typ)
1250                loop
1251                   if E = S then
1252                      return True;
1253                   end if;
1254                   Next_Entity (E);
1255                end loop;
1256             end if;
1257
1258             S := Scope (S);
1259          end loop;
1260
1261          return False;
1262       end Is_Public_Operation;
1263
1264    --  Start of processing for Check_Unprotected_Access
1265
1266    begin
1267       if Nkind (Expr) = N_Attribute_Reference
1268         and then Attribute_Name (Expr) = Name_Unchecked_Access
1269       then
1270          Cont_Encl_Typ := Enclosing_Protected_Type (Context);
1271          Pref_Encl_Typ := Enclosing_Protected_Type (Prefix (Expr));
1272
1273          --  Check whether we are trying to export a protected component to a
1274          --  context with an equal or lower access level.
1275
1276          if Present (Pref_Encl_Typ)
1277            and then No (Cont_Encl_Typ)
1278            and then Is_Public_Operation
1279            and then Scope_Depth (Pref_Encl_Typ) >=
1280                       Object_Access_Level (Context)
1281          then
1282             Error_Msg_N
1283               ("?possible unprotected access to protected data", Expr);
1284          end if;
1285       end if;
1286    end Check_Unprotected_Access;
1287
1288    ---------------
1289    -- Check_VMS --
1290    ---------------
1291
1292    procedure Check_VMS (Construct : Node_Id) is
1293    begin
1294       if not OpenVMS_On_Target then
1295          Error_Msg_N
1296            ("this construct is allowed only in Open'V'M'S", Construct);
1297       end if;
1298    end Check_VMS;
1299
1300    ------------------------
1301    -- Collect_Interfaces --
1302    ------------------------
1303
1304    procedure Collect_Interfaces
1305      (T               : Entity_Id;
1306       Ifaces_List     : out Elist_Id;
1307       Exclude_Parents : Boolean := False;
1308       Use_Full_View   : Boolean := True)
1309    is
1310       procedure Collect (Typ : Entity_Id);
1311       --  Subsidiary subprogram used to traverse the whole list
1312       --  of directly and indirectly implemented interfaces
1313
1314       -------------
1315       -- Collect --
1316       -------------
1317
1318       procedure Collect (Typ : Entity_Id) is
1319          Ancestor   : Entity_Id;
1320          Full_T     : Entity_Id;
1321          Id         : Node_Id;
1322          Iface      : Entity_Id;
1323
1324       begin
1325          Full_T := Typ;
1326
1327          --  Handle private types
1328
1329          if Use_Full_View
1330            and then Is_Private_Type (Typ)
1331            and then Present (Full_View (Typ))
1332          then
1333             Full_T := Full_View (Typ);
1334          end if;
1335
1336          --  Include the ancestor if we are generating the whole list of
1337          --  abstract interfaces.
1338
1339          if Etype (Full_T) /= Typ
1340
1341             --  Protect the frontend against wrong sources. For example:
1342
1343             --    package P is
1344             --      type A is tagged null record;
1345             --      type B is new A with private;
1346             --      type C is new A with private;
1347             --    private
1348             --      type B is new C with null record;
1349             --      type C is new B with null record;
1350             --    end P;
1351
1352            and then Etype (Full_T) /= T
1353          then
1354             Ancestor := Etype (Full_T);
1355             Collect (Ancestor);
1356
1357             if Is_Interface (Ancestor)
1358               and then not Exclude_Parents
1359             then
1360                Append_Unique_Elmt (Ancestor, Ifaces_List);
1361             end if;
1362          end if;
1363
1364          --  Traverse the graph of ancestor interfaces
1365
1366          if Is_Non_Empty_List (Abstract_Interface_List (Full_T)) then
1367             Id := First (Abstract_Interface_List (Full_T));
1368             while Present (Id) loop
1369                Iface := Etype (Id);
1370
1371                --  Protect against wrong uses. For example:
1372                --    type I is interface;
1373                --    type O is tagged null record;
1374                --    type Wrong is new I and O with null record; -- ERROR
1375
1376                if Is_Interface (Iface) then
1377                   if Exclude_Parents
1378                     and then Etype (T) /= T
1379                     and then Interface_Present_In_Ancestor (Etype (T), Iface)
1380                   then
1381                      null;
1382                   else
1383                      Collect (Iface);
1384                      Append_Unique_Elmt (Iface, Ifaces_List);
1385                   end if;
1386                end if;
1387
1388                Next (Id);
1389             end loop;
1390          end if;
1391       end Collect;
1392
1393    --  Start of processing for Collect_Interfaces
1394
1395    begin
1396       pragma Assert (Is_Tagged_Type (T) or else Is_Concurrent_Type (T));
1397       Ifaces_List := New_Elmt_List;
1398       Collect (T);
1399    end Collect_Interfaces;
1400
1401    ----------------------------------
1402    -- Collect_Interface_Components --
1403    ----------------------------------
1404
1405    procedure Collect_Interface_Components
1406      (Tagged_Type     : Entity_Id;
1407       Components_List : out Elist_Id)
1408    is
1409       procedure Collect (Typ : Entity_Id);
1410       --  Subsidiary subprogram used to climb to the parents
1411
1412       -------------
1413       -- Collect --
1414       -------------
1415
1416       procedure Collect (Typ : Entity_Id) is
1417          Tag_Comp   : Entity_Id;
1418          Parent_Typ : Entity_Id;
1419
1420       begin
1421          --  Handle private types
1422
1423          if Present (Full_View (Etype (Typ))) then
1424             Parent_Typ := Full_View (Etype (Typ));
1425          else
1426             Parent_Typ := Etype (Typ);
1427          end if;
1428
1429          if Parent_Typ /= Typ
1430
1431             --  Protect the frontend against wrong sources. For example:
1432
1433             --    package P is
1434             --      type A is tagged null record;
1435             --      type B is new A with private;
1436             --      type C is new A with private;
1437             --    private
1438             --      type B is new C with null record;
1439             --      type C is new B with null record;
1440             --    end P;
1441
1442            and then Parent_Typ /= Tagged_Type
1443          then
1444             Collect (Parent_Typ);
1445          end if;
1446
1447          --  Collect the components containing tags of secondary dispatch
1448          --  tables.
1449
1450          Tag_Comp := Next_Tag_Component (First_Tag_Component (Typ));
1451          while Present (Tag_Comp) loop
1452             pragma Assert (Present (Related_Type (Tag_Comp)));
1453             Append_Elmt (Tag_Comp, Components_List);
1454
1455             Tag_Comp := Next_Tag_Component (Tag_Comp);
1456          end loop;
1457       end Collect;
1458
1459    --  Start of processing for Collect_Interface_Components
1460
1461    begin
1462       pragma Assert (Ekind (Tagged_Type) = E_Record_Type
1463         and then Is_Tagged_Type (Tagged_Type));
1464
1465       Components_List := New_Elmt_List;
1466       Collect (Tagged_Type);
1467    end Collect_Interface_Components;
1468
1469    -----------------------------
1470    -- Collect_Interfaces_Info --
1471    -----------------------------
1472
1473    procedure Collect_Interfaces_Info
1474      (T               : Entity_Id;
1475       Ifaces_List     : out Elist_Id;
1476       Components_List : out Elist_Id;
1477       Tags_List       : out Elist_Id)
1478    is
1479       Comps_List : Elist_Id;
1480       Comp_Elmt  : Elmt_Id;
1481       Comp_Iface : Entity_Id;
1482       Iface_Elmt : Elmt_Id;
1483       Iface      : Entity_Id;
1484
1485       function Search_Tag (Iface : Entity_Id) return Entity_Id;
1486       --  Search for the secondary tag associated with the interface type
1487       --  Iface that is implemented by T.
1488
1489       ----------------
1490       -- Search_Tag --
1491       ----------------
1492
1493       function Search_Tag (Iface : Entity_Id) return Entity_Id is
1494          ADT : Elmt_Id;
1495
1496       begin
1497          ADT := Next_Elmt (Next_Elmt (First_Elmt (Access_Disp_Table (T))));
1498          while Present (ADT)
1499             and then Ekind (Node (ADT)) = E_Constant
1500             and then Related_Type (Node (ADT)) /= Iface
1501          loop
1502             --  Skip the secondary dispatch tables of Iface
1503
1504             Next_Elmt (ADT);
1505             Next_Elmt (ADT);
1506             Next_Elmt (ADT);
1507             Next_Elmt (ADT);
1508          end loop;
1509
1510          pragma Assert (Ekind (Node (ADT)) = E_Constant);
1511          return Node (ADT);
1512       end Search_Tag;
1513
1514    --  Start of processing for Collect_Interfaces_Info
1515
1516    begin
1517       Collect_Interfaces (T, Ifaces_List);
1518       Collect_Interface_Components (T, Comps_List);
1519
1520       --  Search for the record component and tag associated with each
1521       --  interface type of T.
1522
1523       Components_List := New_Elmt_List;
1524       Tags_List       := New_Elmt_List;
1525
1526       Iface_Elmt := First_Elmt (Ifaces_List);
1527       while Present (Iface_Elmt) loop
1528          Iface := Node (Iface_Elmt);
1529
1530          --  Associate the primary tag component and the primary dispatch table
1531          --  with all the interfaces that are parents of T
1532
1533          if Is_Ancestor (Iface, T) then
1534             Append_Elmt (First_Tag_Component (T), Components_List);
1535             Append_Elmt (Node (First_Elmt (Access_Disp_Table (T))), Tags_List);
1536
1537          --  Otherwise search for the tag component and secondary dispatch
1538          --  table of Iface
1539
1540          else
1541             Comp_Elmt := First_Elmt (Comps_List);
1542             while Present (Comp_Elmt) loop
1543                Comp_Iface := Related_Type (Node (Comp_Elmt));
1544
1545                if Comp_Iface = Iface
1546                  or else Is_Ancestor (Iface, Comp_Iface)
1547                then
1548                   Append_Elmt (Node (Comp_Elmt), Components_List);
1549                   Append_Elmt (Search_Tag (Comp_Iface), Tags_List);
1550                   exit;
1551                end if;
1552
1553                Next_Elmt (Comp_Elmt);
1554             end loop;
1555             pragma Assert (Present (Comp_Elmt));
1556          end if;
1557
1558          Next_Elmt (Iface_Elmt);
1559       end loop;
1560    end Collect_Interfaces_Info;
1561
1562    ----------------------------------
1563    -- Collect_Primitive_Operations --
1564    ----------------------------------
1565
1566    function Collect_Primitive_Operations (T : Entity_Id) return Elist_Id is
1567       B_Type         : constant Entity_Id := Base_Type (T);
1568       B_Decl         : constant Node_Id   := Original_Node (Parent (B_Type));
1569       B_Scope        : Entity_Id          := Scope (B_Type);
1570       Op_List        : Elist_Id;
1571       Formal         : Entity_Id;
1572       Is_Prim        : Boolean;
1573       Formal_Derived : Boolean := False;
1574       Id             : Entity_Id;
1575
1576    begin
1577       --  For tagged types, the primitive operations are collected as they
1578       --  are declared, and held in an explicit list which is simply returned.
1579
1580       if Is_Tagged_Type (B_Type) then
1581          return Primitive_Operations (B_Type);
1582
1583       --  An untagged generic type that is a derived type inherits the
1584       --  primitive operations of its parent type. Other formal types only
1585       --  have predefined operators, which are not explicitly represented.
1586
1587       elsif Is_Generic_Type (B_Type) then
1588          if Nkind (B_Decl) = N_Formal_Type_Declaration
1589            and then Nkind (Formal_Type_Definition (B_Decl))
1590              = N_Formal_Derived_Type_Definition
1591          then
1592             Formal_Derived := True;
1593          else
1594             return New_Elmt_List;
1595          end if;
1596       end if;
1597
1598       Op_List := New_Elmt_List;
1599
1600       if B_Scope = Standard_Standard then
1601          if B_Type = Standard_String then
1602             Append_Elmt (Standard_Op_Concat, Op_List);
1603
1604          elsif B_Type = Standard_Wide_String then
1605             Append_Elmt (Standard_Op_Concatw, Op_List);
1606
1607          else
1608             null;
1609          end if;
1610
1611       elsif (Is_Package_Or_Generic_Package (B_Scope)
1612               and then
1613                 Nkind (Parent (Declaration_Node (First_Subtype (T)))) /=
1614                                                             N_Package_Body)
1615         or else Is_Derived_Type (B_Type)
1616       then
1617          --  The primitive operations appear after the base type, except
1618          --  if the derivation happens within the private part of B_Scope
1619          --  and the type is a private type, in which case both the type
1620          --  and some primitive operations may appear before the base
1621          --  type, and the list of candidates starts after the type.
1622
1623          if In_Open_Scopes (B_Scope)
1624            and then Scope (T) = B_Scope
1625            and then In_Private_Part (B_Scope)
1626          then
1627             Id := Next_Entity (T);
1628          else
1629             Id := Next_Entity (B_Type);
1630          end if;
1631
1632          while Present (Id) loop
1633
1634             --  Note that generic formal subprograms are not
1635             --  considered to be primitive operations and thus
1636             --  are never inherited.
1637
1638             if Is_Overloadable (Id)
1639               and then Nkind (Parent (Parent (Id)))
1640                          not in N_Formal_Subprogram_Declaration
1641             then
1642                Is_Prim := False;
1643
1644                if Base_Type (Etype (Id)) = B_Type then
1645                   Is_Prim := True;
1646                else
1647                   Formal := First_Formal (Id);
1648                   while Present (Formal) loop
1649                      if Base_Type (Etype (Formal)) = B_Type then
1650                         Is_Prim := True;
1651                         exit;
1652
1653                      elsif Ekind (Etype (Formal)) = E_Anonymous_Access_Type
1654                        and then Base_Type
1655                          (Designated_Type (Etype (Formal))) = B_Type
1656                      then
1657                         Is_Prim := True;
1658                         exit;
1659                      end if;
1660
1661                      Next_Formal (Formal);
1662                   end loop;
1663                end if;
1664
1665                --  For a formal derived type, the only primitives are the
1666                --  ones inherited from the parent type. Operations appearing
1667                --  in the package declaration are not primitive for it.
1668
1669                if Is_Prim
1670                  and then (not Formal_Derived
1671                             or else Present (Alias (Id)))
1672                then
1673                   --  In the special case of an equality operator aliased to
1674                   --  an overriding dispatching equality belonging to the same
1675                   --  type, we don't include it in the list of primitives.
1676                   --  This avoids inheriting multiple equality operators when
1677                   --  deriving from untagged private types whose full type is
1678                   --  tagged, which can otherwise cause ambiguities. Note that
1679                   --  this should only happen for this kind of untagged parent
1680                   --  type, since normally dispatching operations are inherited
1681                   --  using the type's Primitive_Operations list.
1682
1683                   if Chars (Id) = Name_Op_Eq
1684                     and then Is_Dispatching_Operation (Id)
1685                     and then Present (Alias (Id))
1686                     and then Is_Overriding_Operation (Alias (Id))
1687                     and then Base_Type (Etype (First_Entity (Id))) =
1688                                Base_Type (Etype (First_Entity (Alias (Id))))
1689                   then
1690                      null;
1691
1692                   --  Include the subprogram in the list of primitives
1693
1694                   else
1695                      Append_Elmt (Id, Op_List);
1696                   end if;
1697                end if;
1698             end if;
1699
1700             Next_Entity (Id);
1701
1702             --  For a type declared in System, some of its operations
1703             --  may appear in  the target-specific extension to System.
1704
1705             if No (Id)
1706               and then Chars (B_Scope) = Name_System
1707               and then Scope (B_Scope) = Standard_Standard
1708               and then Present_System_Aux
1709             then
1710                B_Scope := System_Aux_Id;
1711                Id := First_Entity (System_Aux_Id);
1712             end if;
1713          end loop;
1714       end if;
1715
1716       return Op_List;
1717    end Collect_Primitive_Operations;
1718
1719    -----------------------------------
1720    -- Compile_Time_Constraint_Error --
1721    -----------------------------------
1722
1723    function Compile_Time_Constraint_Error
1724      (N    : Node_Id;
1725       Msg  : String;
1726       Ent  : Entity_Id  := Empty;
1727       Loc  : Source_Ptr := No_Location;
1728       Warn : Boolean    := False) return Node_Id
1729    is
1730       Msgc : String (1 .. Msg'Length + 2);
1731       --  Copy of message, with room for possible ? and ! at end
1732
1733       Msgl : Natural;
1734       Wmsg : Boolean;
1735       P    : Node_Id;
1736       OldP : Node_Id;
1737       Msgs : Boolean;
1738       Eloc : Source_Ptr;
1739
1740    begin
1741       --  A static constraint error in an instance body is not a fatal error.
1742       --  we choose to inhibit the message altogether, because there is no
1743       --  obvious node (for now) on which to post it. On the other hand the
1744       --  offending node must be replaced with a constraint_error in any case.
1745
1746       --  No messages are generated if we already posted an error on this node
1747
1748       if not Error_Posted (N) then
1749          if Loc /= No_Location then
1750             Eloc := Loc;
1751          else
1752             Eloc := Sloc (N);
1753          end if;
1754
1755          Msgc (1 .. Msg'Length) := Msg;
1756          Msgl := Msg'Length;
1757
1758          --  Message is a warning, even in Ada 95 case
1759
1760          if Msg (Msg'Last) = '?' then
1761             Wmsg := True;
1762
1763          --  In Ada 83, all messages are warnings. In the private part and
1764          --  the body of an instance, constraint_checks are only warnings.
1765          --  We also make this a warning if the Warn parameter is set.
1766
1767          elsif Warn
1768            or else (Ada_Version = Ada_83 and then Comes_From_Source (N))
1769          then
1770             Msgl := Msgl + 1;
1771             Msgc (Msgl) := '?';
1772             Wmsg := True;
1773
1774          elsif In_Instance_Not_Visible then
1775             Msgl := Msgl + 1;
1776             Msgc (Msgl) := '?';
1777             Wmsg := True;
1778
1779          --  Otherwise we have a real error message (Ada 95 static case)
1780          --  and we make this an unconditional message. Note that in the
1781          --  warning case we do not make the message unconditional, it seems
1782          --  quite reasonable to delete messages like this (about exceptions
1783          --  that will be raised) in dead code.
1784
1785          else
1786             Wmsg := False;
1787             Msgl := Msgl + 1;
1788             Msgc (Msgl) := '!';
1789          end if;
1790
1791          --  Should we generate a warning? The answer is not quite yes. The
1792          --  very annoying exception occurs in the case of a short circuit
1793          --  operator where the left operand is static and decisive. Climb
1794          --  parents to see if that is the case we have here. Conditional
1795          --  expressions with decisive conditions are a similar situation.
1796
1797          Msgs := True;
1798          P := N;
1799          loop
1800             OldP := P;
1801             P := Parent (P);
1802
1803             --  And then with False as left operand
1804
1805             if Nkind (P) = N_And_Then
1806               and then Compile_Time_Known_Value (Left_Opnd (P))
1807               and then Is_False (Expr_Value (Left_Opnd (P)))
1808             then
1809                Msgs := False;
1810                exit;
1811
1812             --  OR ELSE with True as left operand
1813
1814             elsif Nkind (P) = N_Or_Else
1815               and then Compile_Time_Known_Value (Left_Opnd (P))
1816               and then Is_True (Expr_Value (Left_Opnd (P)))
1817             then
1818                Msgs := False;
1819                exit;
1820
1821             --  Conditional expression
1822
1823             elsif Nkind (P) = N_Conditional_Expression then
1824                declare
1825                   Cond : constant Node_Id := First (Expressions (P));
1826                   Texp : constant Node_Id := Next (Cond);
1827                   Fexp : constant Node_Id := Next (Texp);
1828
1829                begin
1830                   if Compile_Time_Known_Value (Cond) then
1831
1832                      --  Condition is True and we are in the right operand
1833
1834                      if Is_True (Expr_Value (Cond))
1835                        and then OldP = Fexp
1836                      then
1837                         Msgs := False;
1838                         exit;
1839
1840                      --  Condition is False and we are in the left operand
1841
1842                      elsif Is_False (Expr_Value (Cond))
1843                        and then OldP = Texp
1844                      then
1845                         Msgs := False;
1846                         exit;
1847                      end if;
1848                   end if;
1849                end;
1850
1851             --  Special case for component association in aggregates, where
1852             --  we want to keep climbing up to the parent aggregate.
1853
1854             elsif Nkind (P) = N_Component_Association
1855               and then Nkind (Parent (P)) = N_Aggregate
1856             then
1857                null;
1858
1859             --  Keep going if within subexpression
1860
1861             else
1862                exit when Nkind (P) not in N_Subexpr;
1863             end if;
1864          end loop;
1865
1866          if Msgs then
1867             if Present (Ent) then
1868                Error_Msg_NEL (Msgc (1 .. Msgl), N, Ent, Eloc);
1869             else
1870                Error_Msg_NEL (Msgc (1 .. Msgl), N, Etype (N), Eloc);
1871             end if;
1872
1873             if Wmsg then
1874                if Inside_Init_Proc then
1875                   Error_Msg_NEL
1876                     ("\?& will be raised for objects of this type",
1877                      N, Standard_Constraint_Error, Eloc);
1878                else
1879                   Error_Msg_NEL
1880                     ("\?& will be raised at run time",
1881                      N, Standard_Constraint_Error, Eloc);
1882                end if;
1883
1884             else
1885                Error_Msg
1886                  ("\static expression fails Constraint_Check", Eloc);
1887                Set_Error_Posted (N);
1888             end if;
1889          end if;
1890       end if;
1891
1892       return N;
1893    end Compile_Time_Constraint_Error;
1894
1895    -----------------------
1896    -- Conditional_Delay --
1897    -----------------------
1898
1899    procedure Conditional_Delay (New_Ent, Old_Ent : Entity_Id) is
1900    begin
1901       if Has_Delayed_Freeze (Old_Ent) and then not Is_Frozen (Old_Ent) then
1902          Set_Has_Delayed_Freeze (New_Ent);
1903       end if;
1904    end Conditional_Delay;
1905
1906    -------------------------
1907    -- Copy_Parameter_List --
1908    -------------------------
1909
1910    function Copy_Parameter_List (Subp_Id : Entity_Id) return List_Id is
1911       Loc    : constant Source_Ptr := Sloc (Subp_Id);
1912       Plist  : List_Id;
1913       Formal : Entity_Id;
1914
1915    begin
1916       if No (First_Formal (Subp_Id)) then
1917          return No_List;
1918       else
1919          Plist := New_List;
1920          Formal := First_Formal (Subp_Id);
1921          while Present (Formal) loop
1922             Append
1923               (Make_Parameter_Specification (Loc,
1924                 Defining_Identifier =>
1925                   Make_Defining_Identifier (Sloc (Formal),
1926                     Chars => Chars (Formal)),
1927                 In_Present  => In_Present (Parent (Formal)),
1928                 Out_Present => Out_Present (Parent (Formal)),
1929              Parameter_Type =>
1930                   New_Reference_To (Etype (Formal), Loc),
1931                 Expression =>
1932                   New_Copy_Tree (Expression (Parent (Formal)))),
1933               Plist);
1934
1935             Next_Formal (Formal);
1936          end loop;
1937       end if;
1938
1939       return Plist;
1940    end Copy_Parameter_List;
1941
1942    --------------------
1943    -- Current_Entity --
1944    --------------------
1945
1946    --  The currently visible definition for a given identifier is the
1947    --  one most chained at the start of the visibility chain, i.e. the
1948    --  one that is referenced by the Node_Id value of the name of the
1949    --  given identifier.
1950
1951    function Current_Entity (N : Node_Id) return Entity_Id is
1952    begin
1953       return Get_Name_Entity_Id (Chars (N));
1954    end Current_Entity;
1955
1956    -----------------------------
1957    -- Current_Entity_In_Scope --
1958    -----------------------------
1959
1960    function Current_Entity_In_Scope (N : Node_Id) return Entity_Id is
1961       E  : Entity_Id;
1962       CS : constant Entity_Id := Current_Scope;
1963
1964       Transient_Case : constant Boolean := Scope_Is_Transient;
1965
1966    begin
1967       E := Get_Name_Entity_Id (Chars (N));
1968       while Present (E)
1969         and then Scope (E) /= CS
1970         and then (not Transient_Case or else Scope (E) /= Scope (CS))
1971       loop
1972          E := Homonym (E);
1973       end loop;
1974
1975       return E;
1976    end Current_Entity_In_Scope;
1977
1978    -------------------
1979    -- Current_Scope --
1980    -------------------
1981
1982    function Current_Scope return Entity_Id is
1983    begin
1984       if Scope_Stack.Last = -1 then
1985          return Standard_Standard;
1986       else
1987          declare
1988             C : constant Entity_Id :=
1989                   Scope_Stack.Table (Scope_Stack.Last).Entity;
1990          begin
1991             if Present (C) then
1992                return C;
1993             else
1994                return Standard_Standard;
1995             end if;
1996          end;
1997       end if;
1998    end Current_Scope;
1999
2000    ------------------------
2001    -- Current_Subprogram --
2002    ------------------------
2003
2004    function Current_Subprogram return Entity_Id is
2005       Scop : constant Entity_Id := Current_Scope;
2006    begin
2007       if Is_Subprogram (Scop) or else Is_Generic_Subprogram (Scop) then
2008          return Scop;
2009       else
2010          return Enclosing_Subprogram (Scop);
2011       end if;
2012    end Current_Subprogram;
2013
2014    ---------------------
2015    -- Defining_Entity --
2016    ---------------------
2017
2018    function Defining_Entity (N : Node_Id) return Entity_Id is
2019       K   : constant Node_Kind := Nkind (N);
2020       Err : Entity_Id := Empty;
2021
2022    begin
2023       case K is
2024          when
2025            N_Subprogram_Declaration                 |
2026            N_Abstract_Subprogram_Declaration        |
2027            N_Subprogram_Body                        |
2028            N_Package_Declaration                    |
2029            N_Subprogram_Renaming_Declaration        |
2030            N_Subprogram_Body_Stub                   |
2031            N_Generic_Subprogram_Declaration         |
2032            N_Generic_Package_Declaration            |
2033            N_Formal_Subprogram_Declaration
2034          =>
2035             return Defining_Entity (Specification (N));
2036
2037          when
2038            N_Component_Declaration                  |
2039            N_Defining_Program_Unit_Name             |
2040            N_Discriminant_Specification             |
2041            N_Entry_Body                             |
2042            N_Entry_Declaration                      |
2043            N_Entry_Index_Specification              |
2044            N_Exception_Declaration                  |
2045            N_Exception_Renaming_Declaration         |
2046            N_Formal_Object_Declaration              |
2047            N_Formal_Package_Declaration             |
2048            N_Formal_Type_Declaration                |
2049            N_Full_Type_Declaration                  |
2050            N_Implicit_Label_Declaration             |
2051            N_Incomplete_Type_Declaration            |
2052            N_Loop_Parameter_Specification           |
2053            N_Number_Declaration                     |
2054            N_Object_Declaration                     |
2055            N_Object_Renaming_Declaration            |
2056            N_Package_Body_Stub                      |
2057            N_Parameter_Specification                |
2058            N_Private_Extension_Declaration          |
2059            N_Private_Type_Declaration               |
2060            N_Protected_Body                         |
2061            N_Protected_Body_Stub                    |
2062            N_Protected_Type_Declaration             |
2063            N_Single_Protected_Declaration           |
2064            N_Single_Task_Declaration                |
2065            N_Subtype_Declaration                    |
2066            N_Task_Body                              |
2067            N_Task_Body_Stub                         |
2068            N_Task_Type_Declaration
2069          =>
2070             return Defining_Identifier (N);
2071
2072          when N_Subunit =>
2073             return Defining_Entity (Proper_Body (N));
2074
2075          when
2076            N_Function_Instantiation                 |
2077            N_Function_Specification                 |
2078            N_Generic_Function_Renaming_Declaration  |
2079            N_Generic_Package_Renaming_Declaration   |
2080            N_Generic_Procedure_Renaming_Declaration |
2081            N_Package_Body                           |
2082            N_Package_Instantiation                  |
2083            N_Package_Renaming_Declaration           |
2084            N_Package_Specification                  |
2085            N_Procedure_Instantiation                |
2086            N_Procedure_Specification
2087          =>
2088             declare
2089                Nam : constant Node_Id := Defining_Unit_Name (N);
2090
2091             begin
2092                if Nkind (Nam) in N_Entity then
2093                   return Nam;
2094
2095                --  For Error, make up a name and attach to declaration
2096                --  so we can continue semantic analysis
2097
2098                elsif Nam = Error then
2099                   Err := Make_Temporary (Sloc (N), 'T');
2100                   Set_Defining_Unit_Name (N, Err);
2101
2102                   return Err;
2103                --  If not an entity, get defining identifier
2104
2105                else
2106                   return Defining_Identifier (Nam);
2107                end if;
2108             end;
2109
2110          when N_Block_Statement =>
2111             return Entity (Identifier (N));
2112
2113          when others =>
2114             raise Program_Error;
2115
2116       end case;
2117    end Defining_Entity;
2118
2119    --------------------------
2120    -- Denotes_Discriminant --
2121    --------------------------
2122
2123    function Denotes_Discriminant
2124      (N                : Node_Id;
2125       Check_Concurrent : Boolean := False) return Boolean
2126    is
2127       E : Entity_Id;
2128    begin
2129       if not Is_Entity_Name (N)
2130         or else No (Entity (N))
2131       then
2132          return False;
2133       else
2134          E := Entity (N);
2135       end if;
2136
2137       --  If we are checking for a protected type, the discriminant may have
2138       --  been rewritten as the corresponding discriminal of the original type
2139       --  or of the corresponding concurrent record, depending on whether we
2140       --  are in the spec or body of the protected type.
2141
2142       return Ekind (E) = E_Discriminant
2143         or else
2144           (Check_Concurrent
2145             and then Ekind (E) = E_In_Parameter
2146             and then Present (Discriminal_Link (E))
2147             and then
2148               (Is_Concurrent_Type (Scope (Discriminal_Link (E)))
2149                 or else
2150                   Is_Concurrent_Record_Type (Scope (Discriminal_Link (E)))));
2151
2152    end Denotes_Discriminant;
2153
2154    -------------------------
2155    -- Denotes_Same_Object --
2156    -------------------------
2157
2158    function Denotes_Same_Object (A1, A2 : Node_Id) return Boolean is
2159    begin
2160       --  If we have entity names, then must be same entity
2161
2162       if Is_Entity_Name (A1) then
2163          if Is_Entity_Name (A2) then
2164             return Entity (A1) = Entity (A2);
2165          else
2166             return False;
2167          end if;
2168
2169       --  No match if not same node kind
2170
2171       elsif Nkind (A1) /= Nkind (A2) then
2172          return False;
2173
2174       --  For selected components, must have same prefix and selector
2175
2176       elsif Nkind (A1) = N_Selected_Component then
2177          return Denotes_Same_Object (Prefix (A1), Prefix (A2))
2178            and then
2179          Entity (Selector_Name (A1)) = Entity (Selector_Name (A2));
2180
2181       --  For explicit dereferences, prefixes must be same
2182
2183       elsif Nkind (A1) = N_Explicit_Dereference then
2184          return Denotes_Same_Object (Prefix (A1), Prefix (A2));
2185
2186       --  For indexed components, prefixes and all subscripts must be the same
2187
2188       elsif Nkind (A1) = N_Indexed_Component then
2189          if Denotes_Same_Object (Prefix (A1), Prefix (A2)) then
2190             declare
2191                Indx1 : Node_Id;
2192                Indx2 : Node_Id;
2193
2194             begin
2195                Indx1 := First (Expressions (A1));
2196                Indx2 := First (Expressions (A2));
2197                while Present (Indx1) loop
2198
2199                   --  Shouldn't we be checking that values are the same???
2200
2201                   if not Denotes_Same_Object (Indx1, Indx2) then
2202                      return False;
2203                   end if;
2204
2205                   Next (Indx1);
2206                   Next (Indx2);
2207                end loop;
2208
2209                return True;
2210             end;
2211          else
2212             return False;
2213          end if;
2214
2215       --  For slices, prefixes must match and bounds must match
2216
2217       elsif Nkind (A1) = N_Slice
2218         and then Denotes_Same_Object (Prefix (A1), Prefix (A2))
2219       then
2220          declare
2221             Lo1, Lo2, Hi1, Hi2 : Node_Id;
2222
2223          begin
2224             Get_Index_Bounds (Etype (A1), Lo1, Hi1);
2225             Get_Index_Bounds (Etype (A2), Lo2, Hi2);
2226
2227             --  Check whether bounds are statically identical. There is no
2228             --  attempt to detect partial overlap of slices.
2229
2230             --  What about an array and a slice of an array???
2231
2232             return Denotes_Same_Object (Lo1, Lo2)
2233               and then Denotes_Same_Object (Hi1, Hi2);
2234          end;
2235
2236          --  Literals will appear as indices. Isn't this where we should check
2237          --  Known_At_Compile_Time at least if we are generating warnings ???
2238
2239       elsif Nkind (A1) = N_Integer_Literal then
2240          return Intval (A1) = Intval (A2);
2241
2242       else
2243          return False;
2244       end if;
2245    end Denotes_Same_Object;
2246
2247    -------------------------
2248    -- Denotes_Same_Prefix --
2249    -------------------------
2250
2251    function Denotes_Same_Prefix (A1, A2 : Node_Id) return Boolean is
2252
2253    begin
2254       if Is_Entity_Name (A1) then
2255          if Nkind_In (A2, N_Selected_Component, N_Indexed_Component) then
2256             return Denotes_Same_Object (A1, Prefix (A2))
2257               or else Denotes_Same_Prefix (A1, Prefix (A2));
2258          else
2259             return False;
2260          end if;
2261
2262       elsif Is_Entity_Name (A2) then
2263          return Denotes_Same_Prefix (A2, A1);
2264
2265       elsif Nkind_In (A1, N_Selected_Component, N_Indexed_Component, N_Slice)
2266               and then
2267             Nkind_In (A2, N_Selected_Component, N_Indexed_Component, N_Slice)
2268       then
2269          declare
2270             Root1, Root2 : Node_Id;
2271             Depth1, Depth2 : Int := 0;
2272
2273          begin
2274             Root1 := Prefix (A1);
2275             while not Is_Entity_Name (Root1) loop
2276                if not Nkind_In
2277                  (Root1, N_Selected_Component, N_Indexed_Component)
2278                then
2279                   return False;
2280                else
2281                   Root1 := Prefix (Root1);
2282                end if;
2283
2284                Depth1 := Depth1 + 1;
2285             end loop;
2286
2287             Root2 := Prefix (A2);
2288             while not Is_Entity_Name (Root2) loop
2289                if not Nkind_In
2290                  (Root2, N_Selected_Component, N_Indexed_Component)
2291                then
2292                   return False;
2293                else
2294                   Root2 := Prefix (Root2);
2295                end if;
2296
2297                Depth2 := Depth2 + 1;
2298             end loop;
2299
2300             --  If both have the same depth and they do not denote the same
2301             --  object, they are disjoint and not warning is needed.
2302
2303             if Depth1 = Depth2 then
2304                return False;
2305
2306             elsif Depth1 > Depth2 then
2307                Root1 := Prefix (A1);
2308                for I in 1 .. Depth1 - Depth2 - 1 loop
2309                   Root1 := Prefix (Root1);
2310                end loop;
2311
2312                return Denotes_Same_Object (Root1, A2);
2313
2314             else
2315                Root2 := Prefix (A2);
2316                for I in 1 .. Depth2 - Depth1 - 1 loop
2317                   Root2 := Prefix (Root2);
2318                end loop;
2319
2320                return Denotes_Same_Object (A1, Root2);
2321             end if;
2322          end;
2323
2324       else
2325          return False;
2326       end if;
2327    end Denotes_Same_Prefix;
2328
2329    ----------------------
2330    -- Denotes_Variable --
2331    ----------------------
2332
2333    function Denotes_Variable (N : Node_Id) return Boolean is
2334    begin
2335       return Is_Variable (N) and then Paren_Count (N) = 0;
2336    end Denotes_Variable;
2337
2338    -----------------------------
2339    -- Depends_On_Discriminant --
2340    -----------------------------
2341
2342    function Depends_On_Discriminant (N : Node_Id) return Boolean is
2343       L : Node_Id;
2344       H : Node_Id;
2345
2346    begin
2347       Get_Index_Bounds (N, L, H);
2348       return Denotes_Discriminant (L) or else Denotes_Discriminant (H);
2349    end Depends_On_Discriminant;
2350
2351    -------------------------
2352    -- Designate_Same_Unit --
2353    -------------------------
2354
2355    function Designate_Same_Unit
2356      (Name1 : Node_Id;
2357       Name2 : Node_Id) return Boolean
2358    is
2359       K1 : constant Node_Kind := Nkind (Name1);
2360       K2 : constant Node_Kind := Nkind (Name2);
2361
2362       function Prefix_Node (N : Node_Id) return Node_Id;
2363       --  Returns the parent unit name node of a defining program unit name
2364       --  or the prefix if N is a selected component or an expanded name.
2365
2366       function Select_Node (N : Node_Id) return Node_Id;
2367       --  Returns the defining identifier node of a defining program unit
2368       --  name or  the selector node if N is a selected component or an
2369       --  expanded name.
2370
2371       -----------------
2372       -- Prefix_Node --
2373       -----------------
2374
2375       function Prefix_Node (N : Node_Id) return Node_Id is
2376       begin
2377          if Nkind (N) = N_Defining_Program_Unit_Name then
2378             return Name (N);
2379
2380          else
2381             return Prefix (N);
2382          end if;
2383       end Prefix_Node;
2384
2385       -----------------
2386       -- Select_Node --
2387       -----------------
2388
2389       function Select_Node (N : Node_Id) return Node_Id is
2390       begin
2391          if Nkind (N) = N_Defining_Program_Unit_Name then
2392             return Defining_Identifier (N);
2393
2394          else
2395             return Selector_Name (N);
2396          end if;
2397       end Select_Node;
2398
2399    --  Start of processing for Designate_Next_Unit
2400
2401    begin
2402       if (K1 = N_Identifier or else
2403           K1 = N_Defining_Identifier)
2404         and then
2405          (K2 = N_Identifier or else
2406           K2 = N_Defining_Identifier)
2407       then
2408          return Chars (Name1) = Chars (Name2);
2409
2410       elsif
2411          (K1 = N_Expanded_Name      or else
2412           K1 = N_Selected_Component or else
2413           K1 = N_Defining_Program_Unit_Name)
2414         and then
2415          (K2 = N_Expanded_Name      or else
2416           K2 = N_Selected_Component or else
2417           K2 = N_Defining_Program_Unit_Name)
2418       then
2419          return
2420            (Chars (Select_Node (Name1)) = Chars (Select_Node (Name2)))
2421              and then
2422                Designate_Same_Unit (Prefix_Node (Name1), Prefix_Node (Name2));
2423
2424       else
2425          return False;
2426       end if;
2427    end Designate_Same_Unit;
2428
2429    ----------------------------
2430    -- Enclosing_Generic_Body --
2431    ----------------------------
2432
2433    function Enclosing_Generic_Body
2434      (N : Node_Id) return Node_Id
2435    is
2436       P    : Node_Id;
2437       Decl : Node_Id;
2438       Spec : Node_Id;
2439
2440    begin
2441       P := Parent (N);
2442       while Present (P) loop
2443          if Nkind (P) = N_Package_Body
2444            or else Nkind (P) = N_Subprogram_Body
2445          then
2446             Spec := Corresponding_Spec (P);
2447
2448             if Present (Spec) then
2449                Decl := Unit_Declaration_Node (Spec);
2450
2451                if Nkind (Decl) = N_Generic_Package_Declaration
2452                  or else Nkind (Decl) = N_Generic_Subprogram_Declaration
2453                then
2454                   return P;
2455                end if;
2456             end if;
2457          end if;
2458
2459          P := Parent (P);
2460       end loop;
2461
2462       return Empty;
2463    end Enclosing_Generic_Body;
2464
2465    ----------------------------
2466    -- Enclosing_Generic_Unit --
2467    ----------------------------
2468
2469    function Enclosing_Generic_Unit
2470      (N : Node_Id) return Node_Id
2471    is
2472       P    : Node_Id;
2473       Decl : Node_Id;
2474       Spec : Node_Id;
2475
2476    begin
2477       P := Parent (N);
2478       while Present (P) loop
2479          if Nkind (P) = N_Generic_Package_Declaration
2480            or else Nkind (P) = N_Generic_Subprogram_Declaration
2481          then
2482             return P;
2483
2484          elsif Nkind (P) = N_Package_Body
2485            or else Nkind (P) = N_Subprogram_Body
2486          then
2487             Spec := Corresponding_Spec (P);
2488
2489             if Present (Spec) then
2490                Decl := Unit_Declaration_Node (Spec);
2491
2492                if Nkind (Decl) = N_Generic_Package_Declaration
2493                  or else Nkind (Decl) = N_Generic_Subprogram_Declaration
2494                then
2495                   return Decl;
2496                end if;
2497             end if;
2498          end if;
2499
2500          P := Parent (P);
2501       end loop;
2502
2503       return Empty;
2504    end Enclosing_Generic_Unit;
2505
2506    -------------------------------
2507    -- Enclosing_Lib_Unit_Entity --
2508    -------------------------------
2509
2510    function Enclosing_Lib_Unit_Entity return Entity_Id is
2511       Unit_Entity : Entity_Id;
2512
2513    begin
2514       --  Look for enclosing library unit entity by following scope links.
2515       --  Equivalent to, but faster than indexing through the scope stack.
2516
2517       Unit_Entity := Current_Scope;
2518       while (Present (Scope (Unit_Entity))
2519         and then Scope (Unit_Entity) /= Standard_Standard)
2520         and not Is_Child_Unit (Unit_Entity)
2521       loop
2522          Unit_Entity := Scope (Unit_Entity);
2523       end loop;
2524
2525       return Unit_Entity;
2526    end Enclosing_Lib_Unit_Entity;
2527
2528    -----------------------------
2529    -- Enclosing_Lib_Unit_Node --
2530    -----------------------------
2531
2532    function Enclosing_Lib_Unit_Node (N : Node_Id) return Node_Id is
2533       Current_Node : Node_Id;
2534
2535    begin
2536       Current_Node := N;
2537       while Present (Current_Node)
2538         and then Nkind (Current_Node) /= N_Compilation_Unit
2539       loop
2540          Current_Node := Parent (Current_Node);
2541       end loop;
2542
2543       if Nkind (Current_Node) /= N_Compilation_Unit then
2544          return Empty;
2545       end if;
2546
2547       return Current_Node;
2548    end Enclosing_Lib_Unit_Node;
2549
2550    --------------------------
2551    -- Enclosing_Subprogram --
2552    --------------------------
2553
2554    function Enclosing_Subprogram (E : Entity_Id) return Entity_Id is
2555       Dynamic_Scope : constant Entity_Id := Enclosing_Dynamic_Scope (E);
2556
2557    begin
2558       if Dynamic_Scope = Standard_Standard then
2559          return Empty;
2560
2561       elsif Dynamic_Scope = Empty then
2562          return Empty;
2563
2564       elsif Ekind (Dynamic_Scope) = E_Subprogram_Body then
2565          return Corresponding_Spec (Parent (Parent (Dynamic_Scope)));
2566
2567       elsif Ekind (Dynamic_Scope) = E_Block
2568         or else Ekind (Dynamic_Scope) = E_Return_Statement
2569       then
2570          return Enclosing_Subprogram (Dynamic_Scope);
2571
2572       elsif Ekind (Dynamic_Scope) = E_Task_Type then
2573          return Get_Task_Body_Procedure (Dynamic_Scope);
2574
2575       --  No body is generated if the protected operation is eliminated
2576
2577       elsif Convention (Dynamic_Scope) = Convention_Protected
2578         and then not Is_Eliminated (Dynamic_Scope)
2579         and then Present (Protected_Body_Subprogram (Dynamic_Scope))
2580       then
2581          return Protected_Body_Subprogram (Dynamic_Scope);
2582
2583       else
2584          return Dynamic_Scope;
2585       end if;
2586    end Enclosing_Subprogram;
2587
2588    ------------------------
2589    -- Ensure_Freeze_Node --
2590    ------------------------
2591
2592    procedure Ensure_Freeze_Node (E : Entity_Id) is
2593       FN : Node_Id;
2594
2595    begin
2596       if No (Freeze_Node (E)) then
2597          FN := Make_Freeze_Entity (Sloc (E));
2598          Set_Has_Delayed_Freeze (E);
2599          Set_Freeze_Node (E, FN);
2600          Set_Access_Types_To_Process (FN, No_Elist);
2601          Set_TSS_Elist (FN, No_Elist);
2602          Set_Entity (FN, E);
2603       end if;
2604    end Ensure_Freeze_Node;
2605
2606    ----------------
2607    -- Enter_Name --
2608    ----------------
2609
2610    procedure Enter_Name (Def_Id : Entity_Id) is
2611       C : constant Entity_Id := Current_Entity (Def_Id);
2612       E : constant Entity_Id := Current_Entity_In_Scope (Def_Id);
2613       S : constant Entity_Id := Current_Scope;
2614
2615    begin
2616       Generate_Definition (Def_Id);
2617
2618       --  Add new name to current scope declarations. Check for duplicate
2619       --  declaration, which may or may not be a genuine error.
2620
2621       if Present (E) then
2622
2623          --  Case of previous entity entered because of a missing declaration
2624          --  or else a bad subtype indication. Best is to use the new entity,
2625          --  and make the previous one invisible.
2626
2627          if Etype (E) = Any_Type then
2628             Set_Is_Immediately_Visible (E, False);
2629
2630          --  Case of renaming declaration constructed for package instances.
2631          --  if there is an explicit declaration with the same identifier,
2632          --  the renaming is not immediately visible any longer, but remains
2633          --  visible through selected component notation.
2634
2635          elsif Nkind (Parent (E)) = N_Package_Renaming_Declaration
2636            and then not Comes_From_Source (E)
2637          then
2638             Set_Is_Immediately_Visible (E, False);
2639
2640          --  The new entity may be the package renaming, which has the same
2641          --  same name as a generic formal which has been seen already.
2642
2643          elsif Nkind (Parent (Def_Id)) = N_Package_Renaming_Declaration
2644             and then not Comes_From_Source (Def_Id)
2645          then
2646             Set_Is_Immediately_Visible (E, False);
2647
2648          --  For a fat pointer corresponding to a remote access to subprogram,
2649          --  we use the same identifier as the RAS type, so that the proper
2650          --  name appears in the stub. This type is only retrieved through
2651          --  the RAS type and never by visibility, and is not added to the
2652          --  visibility list (see below).
2653
2654          elsif Nkind (Parent (Def_Id)) = N_Full_Type_Declaration
2655            and then Present (Corresponding_Remote_Type (Def_Id))
2656          then
2657             null;
2658
2659          --  A controller component for a type extension overrides the
2660          --  inherited component.
2661
2662          elsif Chars (E) = Name_uController then
2663             null;
2664
2665          --  Case of an implicit operation or derived literal. The new entity
2666          --  hides the implicit one,  which is removed from all visibility,
2667          --  i.e. the entity list of its scope, and homonym chain of its name.
2668
2669          elsif (Is_Overloadable (E) and then Is_Inherited_Operation (E))
2670            or else Is_Internal (E)
2671          then
2672             declare
2673                Prev     : Entity_Id;
2674                Prev_Vis : Entity_Id;
2675                Decl     : constant Node_Id := Parent (E);
2676
2677             begin
2678                --  If E is an implicit declaration, it cannot be the first
2679                --  entity in the scope.
2680
2681                Prev := First_Entity (Current_Scope);
2682                while Present (Prev)
2683                  and then Next_Entity (Prev) /= E
2684                loop
2685                   Next_Entity (Prev);
2686                end loop;
2687
2688                if No (Prev) then
2689
2690                   --  If E is not on the entity chain of the current scope,
2691                   --  it is an implicit declaration in the generic formal
2692                   --  part of a generic subprogram. When analyzing the body,
2693                   --  the generic formals are visible but not on the entity
2694                   --  chain of the subprogram. The new entity will become
2695                   --  the visible one in the body.
2696
2697                   pragma Assert
2698                     (Nkind (Parent (Decl)) = N_Generic_Subprogram_Declaration);
2699                   null;
2700
2701                else
2702                   Set_Next_Entity (Prev, Next_Entity (E));
2703
2704                   if No (Next_Entity (Prev)) then
2705                      Set_Last_Entity (Current_Scope, Prev);
2706                   end if;
2707
2708                   if E = Current_Entity (E) then
2709                      Prev_Vis := Empty;
2710
2711                   else
2712                      Prev_Vis := Current_Entity (E);
2713                      while Homonym (Prev_Vis) /= E loop
2714                         Prev_Vis := Homonym (Prev_Vis);
2715                      end loop;
2716                   end if;
2717
2718                   if Present (Prev_Vis)  then
2719
2720                      --  Skip E in the visibility chain
2721
2722                      Set_Homonym (Prev_Vis, Homonym (E));
2723
2724                   else
2725                      Set_Name_Entity_Id (Chars (E), Homonym (E));
2726                   end if;
2727                end if;
2728             end;
2729
2730          --  This section of code could use a comment ???
2731
2732          elsif Present (Etype (E))
2733            and then Is_Concurrent_Type (Etype (E))
2734            and then E = Def_Id
2735          then
2736             return;
2737
2738          --  If the homograph is a protected component renaming, it should not
2739          --  be hiding the current entity. Such renamings are treated as weak
2740          --  declarations.
2741
2742          elsif Is_Prival (E) then
2743             Set_Is_Immediately_Visible (E, False);
2744
2745          --  In this case the current entity is a protected component renaming.
2746          --  Perform minimal decoration by setting the scope and return since
2747          --  the prival should not be hiding other visible entities.
2748
2749          elsif Is_Prival (Def_Id) then
2750             Set_Scope (Def_Id, Current_Scope);
2751             return;
2752
2753          --  Analogous to privals, the discriminal generated for an entry
2754          --  index parameter acts as a weak declaration. Perform minimal
2755          --  decoration to avoid bogus errors.
2756
2757          elsif Is_Discriminal (Def_Id)
2758            and then Ekind (Discriminal_Link (Def_Id)) = E_Entry_Index_Parameter
2759          then
2760             Set_Scope (Def_Id, Current_Scope);
2761             return;
2762
2763          --  In the body or private part of an instance, a type extension
2764          --  may introduce a component with the same name as that of an
2765          --  actual. The legality rule is not enforced, but the semantics
2766          --  of the full type with two components of the same name are not
2767          --  clear at this point ???
2768
2769          elsif In_Instance_Not_Visible then
2770             null;
2771
2772          --  When compiling a package body, some child units may have become
2773          --  visible. They cannot conflict with local entities that hide them.
2774
2775          elsif Is_Child_Unit (E)
2776            and then In_Open_Scopes (Scope (E))
2777            and then not Is_Immediately_Visible (E)
2778          then
2779             null;
2780
2781          --  Conversely, with front-end inlining we may compile the parent
2782          --  body first, and a child unit subsequently. The context is now
2783          --  the parent spec, and body entities are not visible.
2784
2785          elsif Is_Child_Unit (Def_Id)
2786            and then Is_Package_Body_Entity (E)
2787            and then not In_Package_Body (Current_Scope)
2788          then
2789             null;
2790
2791          --  Case of genuine duplicate declaration
2792
2793          else
2794             Error_Msg_Sloc := Sloc (E);
2795
2796             --  If the previous declaration is an incomplete type declaration
2797             --  this may be an attempt to complete it with a private type.
2798             --  The following avoids confusing cascaded errors.
2799
2800             if Nkind (Parent (E)) = N_Incomplete_Type_Declaration
2801               and then Nkind (Parent (Def_Id)) = N_Private_Type_Declaration
2802             then
2803                Error_Msg_N
2804                  ("incomplete type cannot be completed with a private " &
2805                   "declaration", Parent (Def_Id));
2806                Set_Is_Immediately_Visible (E, False);
2807                Set_Full_View (E, Def_Id);
2808
2809             --  An inherited component of a record conflicts with a new
2810             --  discriminant. The discriminant is inserted first in the scope,
2811             --  but the error should be posted on it, not on the component.
2812
2813             elsif Ekind (E) = E_Discriminant
2814               and then Present (Scope (Def_Id))
2815               and then Scope (Def_Id) /= Current_Scope
2816             then
2817                Error_Msg_Sloc := Sloc (Def_Id);
2818                Error_Msg_N ("& conflicts with declaration#", E);
2819                return;
2820
2821             --  If the name of the unit appears in its own context clause,
2822             --  a dummy package with the name has already been created, and
2823             --  the error emitted. Try to continue quietly.
2824
2825             elsif Error_Posted (E)
2826               and then Sloc (E) = No_Location
2827               and then Nkind (Parent (E)) = N_Package_Specification
2828               and then Current_Scope = Standard_Standard
2829             then
2830                Set_Scope (Def_Id, Current_Scope);
2831                return;
2832
2833             else
2834                Error_Msg_N ("& conflicts with declaration#", Def_Id);
2835
2836                --  Avoid cascaded messages with duplicate components in
2837                --  derived types.
2838
2839                if Ekind_In (E, E_Component, E_Discriminant) then
2840                   return;
2841                end if;
2842             end if;
2843
2844             if Nkind (Parent (Parent (Def_Id))) =
2845                 N_Generic_Subprogram_Declaration
2846               and then Def_Id =
2847                 Defining_Entity (Specification (Parent (Parent (Def_Id))))
2848             then
2849                Error_Msg_N ("\generic units cannot be overloaded", Def_Id);
2850             end if;
2851
2852             --  If entity is in standard, then we are in trouble, because
2853             --  it means that we have a library package with a duplicated
2854             --  name. That's hard to recover from, so abort!
2855
2856             if S = Standard_Standard then
2857                raise Unrecoverable_Error;
2858
2859             --  Otherwise we continue with the declaration. Having two
2860             --  identical declarations should not cause us too much trouble!
2861
2862             else
2863                null;
2864             end if;
2865          end if;
2866       end if;
2867
2868       --  If we fall through, declaration is OK , or OK enough to continue
2869
2870       --  If Def_Id is a discriminant or a record component we are in the
2871       --  midst of inheriting components in a derived record definition.
2872       --  Preserve their Ekind and Etype.
2873
2874       if Ekind_In (Def_Id, E_Discriminant, E_Component) then
2875          null;
2876
2877       --  If a type is already set, leave it alone (happens whey a type
2878       --  declaration is reanalyzed following a call to the optimizer)
2879
2880       elsif Present (Etype (Def_Id)) then
2881          null;
2882
2883       --  Otherwise, the kind E_Void insures that premature uses of the entity
2884       --  will be detected. Any_Type insures that no cascaded errors will occur
2885
2886       else
2887          Set_Ekind (Def_Id, E_Void);
2888          Set_Etype (Def_Id, Any_Type);
2889       end if;
2890
2891       --  Inherited discriminants and components in derived record types are
2892       --  immediately visible. Itypes are not.
2893
2894       if Ekind_In (Def_Id, E_Discriminant, E_Component)
2895         or else (No (Corresponding_Remote_Type (Def_Id))
2896                  and then not Is_Itype (Def_Id))
2897       then
2898          Set_Is_Immediately_Visible (Def_Id);
2899          Set_Current_Entity         (Def_Id);
2900       end if;
2901
2902       Set_Homonym       (Def_Id, C);
2903       Append_Entity     (Def_Id, S);
2904       Set_Public_Status (Def_Id);
2905
2906       --  Warn if new entity hides an old one
2907
2908       if Warn_On_Hiding and then Present (C)
2909
2910          --  Don't warn for record components since they always have a well
2911          --  defined scope which does not confuse other uses. Note that in
2912          --  some cases, Ekind has not been set yet.
2913
2914          and then Ekind (C) /= E_Component
2915          and then Ekind (C) /= E_Discriminant
2916          and then Nkind (Parent (C)) /= N_Component_Declaration
2917          and then Ekind (Def_Id) /= E_Component
2918          and then Ekind (Def_Id) /= E_Discriminant
2919          and then Nkind (Parent (Def_Id)) /= N_Component_Declaration
2920
2921          --  Don't warn for one character variables. It is too common to use
2922          --  such variables as locals and will just cause too many false hits.
2923
2924          and then Length_Of_Name (Chars (C)) /= 1
2925
2926          --  Don't warn for non-source entities
2927
2928          and then Comes_From_Source (C)
2929          and then Comes_From_Source (Def_Id)
2930
2931          --  Don't warn unless entity in question is in extended main source
2932
2933          and then In_Extended_Main_Source_Unit (Def_Id)
2934
2935          --  Finally, the hidden entity must be either immediately visible
2936          --  or use visible (from a used package)
2937
2938          and then
2939            (Is_Immediately_Visible (C)
2940               or else
2941             Is_Potentially_Use_Visible (C))
2942       then
2943          Error_Msg_Sloc := Sloc (C);
2944          Error_Msg_N ("declaration hides &#?", Def_Id);
2945       end if;
2946    end Enter_Name;
2947
2948    --------------------------
2949    -- Explain_Limited_Type --
2950    --------------------------
2951
2952    procedure Explain_Limited_Type (T : Entity_Id; N : Node_Id) is
2953       C : Entity_Id;
2954
2955    begin
2956       --  For array, component type must be limited
2957
2958       if Is_Array_Type (T) then
2959          Error_Msg_Node_2 := T;
2960          Error_Msg_NE
2961            ("\component type& of type& is limited", N, Component_Type (T));
2962          Explain_Limited_Type (Component_Type (T), N);
2963
2964       elsif Is_Record_Type (T) then
2965
2966          --  No need for extra messages if explicit limited record
2967
2968          if Is_Limited_Record (Base_Type (T)) then
2969             return;
2970          end if;
2971
2972          --  Otherwise find a limited component. Check only components that
2973          --  come from source, or inherited components that appear in the
2974          --  source of the ancestor.
2975
2976          C := First_Component (T);
2977          while Present (C) loop
2978             if Is_Limited_Type (Etype (C))
2979               and then
2980                 (Comes_From_Source (C)
2981                    or else
2982                      (Present (Original_Record_Component (C))
2983                        and then
2984                          Comes_From_Source (Original_Record_Component (C))))
2985             then
2986                Error_Msg_Node_2 := T;
2987                Error_Msg_NE ("\component& of type& has limited type", N, C);
2988                Explain_Limited_Type (Etype (C), N);
2989                return;
2990             end if;
2991
2992             Next_Component (C);
2993          end loop;
2994
2995          --  The type may be declared explicitly limited, even if no component
2996          --  of it is limited, in which case we fall out of the loop.
2997          return;
2998       end if;
2999    end Explain_Limited_Type;
3000
3001    -----------------
3002    -- Find_Actual --
3003    -----------------
3004
3005    procedure Find_Actual
3006      (N        : Node_Id;
3007       Formal   : out Entity_Id;
3008       Call     : out Node_Id)
3009    is
3010       Parnt  : constant Node_Id := Parent (N);
3011       Actual : Node_Id;
3012
3013    begin
3014       if (Nkind (Parnt) = N_Indexed_Component
3015             or else
3016           Nkind (Parnt) = N_Selected_Component)
3017         and then N = Prefix (Parnt)
3018       then
3019          Find_Actual (Parnt, Formal, Call);
3020          return;
3021
3022       elsif Nkind (Parnt) = N_Parameter_Association
3023         and then N = Explicit_Actual_Parameter (Parnt)
3024       then
3025          Call := Parent (Parnt);
3026
3027       elsif Nkind (Parnt) = N_Procedure_Call_Statement then
3028          Call := Parnt;
3029
3030       else
3031          Formal := Empty;
3032          Call   := Empty;
3033          return;
3034       end if;
3035
3036       --  If we have a call to a subprogram look for the parameter. Note that
3037       --  we exclude overloaded calls, since we don't know enough to be sure
3038       --  of giving the right answer in this case.
3039
3040       if Is_Entity_Name (Name (Call))
3041         and then Present (Entity (Name (Call)))
3042         and then Is_Overloadable (Entity (Name (Call)))
3043         and then not Is_Overloaded (Name (Call))
3044       then
3045          --  Fall here if we are definitely a parameter
3046
3047          Actual := First_Actual (Call);
3048          Formal := First_Formal (Entity (Name (Call)));
3049          while Present (Formal) and then Present (Actual) loop
3050             if Actual = N then
3051                return;
3052             else
3053                Actual := Next_Actual (Actual);
3054                Formal := Next_Formal (Formal);
3055             end if;
3056          end loop;
3057       end if;
3058
3059       --  Fall through here if we did not find matching actual
3060
3061       Formal := Empty;
3062       Call   := Empty;
3063    end Find_Actual;
3064
3065    -------------------------------------
3066    -- Find_Corresponding_Discriminant --
3067    -------------------------------------
3068
3069    function Find_Corresponding_Discriminant
3070      (Id  : Node_Id;
3071       Typ : Entity_Id) return Entity_Id
3072    is
3073       Par_Disc : Entity_Id;
3074       Old_Disc : Entity_Id;
3075       New_Disc : Entity_Id;
3076
3077    begin
3078       Par_Disc := Original_Record_Component (Original_Discriminant (Id));
3079
3080       --  The original type may currently be private, and the discriminant
3081       --  only appear on its full view.
3082
3083       if Is_Private_Type (Scope (Par_Disc))
3084         and then not Has_Discriminants (Scope (Par_Disc))
3085         and then Present (Full_View (Scope (Par_Disc)))
3086       then
3087          Old_Disc := First_Discriminant (Full_View (Scope (Par_Disc)));
3088       else
3089          Old_Disc := First_Discriminant (Scope (Par_Disc));
3090       end if;
3091
3092       if Is_Class_Wide_Type (Typ) then
3093          New_Disc := First_Discriminant (Root_Type (Typ));
3094       else
3095          New_Disc := First_Discriminant (Typ);
3096       end if;
3097
3098       while Present (Old_Disc) and then Present (New_Disc) loop
3099          if Old_Disc = Par_Disc  then
3100             return New_Disc;
3101          else
3102             Next_Discriminant (Old_Disc);
3103             Next_Discriminant (New_Disc);
3104          end if;
3105       end loop;
3106
3107       --  Should always find it
3108
3109       raise Program_Error;
3110    end Find_Corresponding_Discriminant;
3111
3112    --------------------------
3113    -- Find_Overlaid_Entity --
3114    --------------------------
3115
3116    procedure Find_Overlaid_Entity
3117      (N   : Node_Id;
3118       Ent : out Entity_Id;
3119       Off : out Boolean)
3120    is
3121       Expr : Node_Id;
3122
3123    begin
3124       --  We are looking for one of the two following forms:
3125
3126       --    for X'Address use Y'Address
3127
3128       --  or
3129
3130       --    Const : constant Address := expr;
3131       --    ...
3132       --    for X'Address use Const;
3133
3134       --  In the second case, the expr is either Y'Address, or recursively a
3135       --  constant that eventually references Y'Address.
3136
3137       Ent := Empty;
3138       Off := False;
3139
3140       if Nkind (N) = N_Attribute_Definition_Clause
3141         and then Chars (N) = Name_Address
3142       then
3143          Expr := Expression (N);
3144
3145          --  This loop checks the form of the expression for Y'Address,
3146          --  using recursion to deal with intermediate constants.
3147
3148          loop
3149             --  Check for Y'Address
3150
3151             if Nkind (Expr) = N_Attribute_Reference
3152               and then Attribute_Name (Expr) = Name_Address
3153             then
3154                Expr := Prefix (Expr);
3155                exit;
3156
3157                --  Check for Const where Const is a constant entity
3158
3159             elsif Is_Entity_Name (Expr)
3160               and then Ekind (Entity (Expr)) = E_Constant
3161             then
3162                Expr := Constant_Value (Entity (Expr));
3163
3164             --  Anything else does not need checking
3165
3166             else
3167                return;
3168             end if;
3169          end loop;
3170
3171          --  This loop checks the form of the prefix for an entity,
3172          --  using recursion to deal with intermediate components.
3173
3174          loop
3175             --  Check for Y where Y is an entity
3176
3177             if Is_Entity_Name (Expr) then
3178                Ent := Entity (Expr);
3179                return;
3180
3181             --  Check for components
3182
3183             elsif
3184                Nkind_In (Expr, N_Selected_Component, N_Indexed_Component) then
3185
3186                Expr := Prefix (Expr);
3187                Off := True;
3188
3189             --  Anything else does not need checking
3190
3191             else
3192                return;
3193             end if;
3194          end loop;
3195       end if;
3196    end Find_Overlaid_Entity;
3197
3198    -------------------------
3199    -- Find_Parameter_Type --
3200    -------------------------
3201
3202    function Find_Parameter_Type (Param : Node_Id) return Entity_Id is
3203    begin
3204       if Nkind (Param) /= N_Parameter_Specification then
3205          return Empty;
3206
3207       --  For an access parameter, obtain the type from the formal entity
3208       --  itself, because access to subprogram nodes do not carry a type.
3209       --  Shouldn't we always use the formal entity ???
3210
3211       elsif Nkind (Parameter_Type (Param)) = N_Access_Definition then
3212          return Etype (Defining_Identifier (Param));
3213
3214       else
3215          return Etype (Parameter_Type (Param));
3216       end if;
3217    end Find_Parameter_Type;
3218
3219    -----------------------------
3220    -- Find_Static_Alternative --
3221    -----------------------------
3222
3223    function Find_Static_Alternative (N : Node_Id) return Node_Id is
3224       Expr   : constant Node_Id := Expression (N);
3225       Val    : constant Uint    := Expr_Value (Expr);
3226       Alt    : Node_Id;
3227       Choice : Node_Id;
3228
3229    begin
3230       Alt := First (Alternatives (N));
3231
3232       Search : loop
3233          if Nkind (Alt) /= N_Pragma then
3234             Choice := First (Discrete_Choices (Alt));
3235             while Present (Choice) loop
3236
3237                --  Others choice, always matches
3238
3239                if Nkind (Choice) = N_Others_Choice then
3240                   exit Search;
3241
3242                --  Range, check if value is in the range
3243
3244                elsif Nkind (Choice) = N_Range then
3245                   exit Search when
3246                     Val >= Expr_Value (Low_Bound (Choice))
3247                       and then
3248                     Val <= Expr_Value (High_Bound (Choice));
3249
3250                --  Choice is a subtype name. Note that we know it must
3251                --  be a static subtype, since otherwise it would have
3252                --  been diagnosed as illegal.
3253
3254                elsif Is_Entity_Name (Choice)
3255                  and then Is_Type (Entity (Choice))
3256                then
3257                   exit Search when Is_In_Range (Expr, Etype (Choice),
3258                                                 Assume_Valid => False);
3259
3260                --  Choice is a subtype indication
3261
3262                elsif Nkind (Choice) = N_Subtype_Indication then
3263                   declare
3264                      C : constant Node_Id := Constraint (Choice);
3265                      R : constant Node_Id := Range_Expression (C);
3266
3267                   begin
3268                      exit Search when
3269                        Val >= Expr_Value (Low_Bound (R))
3270                          and then
3271                        Val <= Expr_Value (High_Bound (R));
3272                   end;
3273
3274                --  Choice is a simple expression
3275
3276                else
3277                   exit Search when Val = Expr_Value (Choice);
3278                end if;
3279
3280                Next (Choice);
3281             end loop;
3282          end if;
3283
3284          Next (Alt);
3285          pragma Assert (Present (Alt));
3286       end loop Search;
3287
3288       --  The above loop *must* terminate by finding a match, since
3289       --  we know the case statement is valid, and the value of the
3290       --  expression is known at compile time. When we fall out of
3291       --  the loop, Alt points to the alternative that we know will
3292       --  be selected at run time.
3293
3294       return Alt;
3295    end Find_Static_Alternative;
3296
3297    ------------------
3298    -- First_Actual --
3299    ------------------
3300
3301    function First_Actual (Node : Node_Id) return Node_Id is
3302       N : Node_Id;
3303
3304    begin
3305       if No (Parameter_Associations (Node)) then
3306          return Empty;
3307       end if;
3308
3309       N := First (Parameter_Associations (Node));
3310
3311       if Nkind (N) = N_Parameter_Association then
3312          return First_Named_Actual (Node);
3313       else
3314          return N;
3315       end if;
3316    end First_Actual;
3317
3318    -------------------------
3319    -- Full_Qualified_Name --
3320    -------------------------
3321
3322    function Full_Qualified_Name (E : Entity_Id) return String_Id is
3323       Res : String_Id;
3324       pragma Warnings (Off, Res);
3325
3326       function Internal_Full_Qualified_Name (E : Entity_Id) return String_Id;
3327       --  Compute recursively the qualified name without NUL at the end
3328
3329       ----------------------------------
3330       -- Internal_Full_Qualified_Name --
3331       ----------------------------------
3332
3333       function Internal_Full_Qualified_Name (E : Entity_Id) return String_Id is
3334          Ent         : Entity_Id := E;
3335          Parent_Name : String_Id := No_String;
3336
3337       begin
3338          --  Deals properly with child units
3339
3340          if Nkind (Ent) = N_Defining_Program_Unit_Name then
3341             Ent := Defining_Identifier (Ent);
3342          end if;
3343
3344          --  Compute qualification recursively (only "Standard" has no scope)
3345
3346          if Present (Scope (Scope (Ent))) then
3347             Parent_Name := Internal_Full_Qualified_Name (Scope (Ent));
3348          end if;
3349
3350          --  Every entity should have a name except some expanded blocks
3351          --  don't bother about those.
3352
3353          if Chars (Ent) = No_Name then
3354             return Parent_Name;
3355          end if;
3356
3357          --  Add a period between Name and qualification
3358
3359          if Parent_Name /= No_String then
3360             Start_String (Parent_Name);
3361             Store_String_Char (Get_Char_Code ('.'));
3362
3363          else
3364             Start_String;
3365          end if;
3366
3367          --  Generates the entity name in upper case
3368
3369          Get_Decoded_Name_String (Chars (Ent));
3370          Set_All_Upper_Case;
3371          Store_String_Chars (Name_Buffer (1 .. Name_Len));
3372          return End_String;
3373       end Internal_Full_Qualified_Name;
3374
3375    --  Start of processing for Full_Qualified_Name
3376
3377    begin
3378       Res := Internal_Full_Qualified_Name (E);
3379       Store_String_Char (Get_Char_Code (ASCII.NUL));
3380       return End_String;
3381    end Full_Qualified_Name;
3382
3383    -----------------------
3384    -- Gather_Components --
3385    -----------------------
3386
3387    procedure Gather_Components
3388      (Typ           : Entity_Id;
3389       Comp_List     : Node_Id;
3390       Governed_By   : List_Id;
3391       Into          : Elist_Id;
3392       Report_Errors : out Boolean)
3393    is
3394       Assoc           : Node_Id;
3395       Variant         : Node_Id;
3396       Discrete_Choice : Node_Id;
3397       Comp_Item       : Node_Id;
3398
3399       Discrim       : Entity_Id;
3400       Discrim_Name  : Node_Id;
3401       Discrim_Value : Node_Id;
3402
3403    begin
3404       Report_Errors := False;
3405
3406       if No (Comp_List) or else Null_Present (Comp_List) then
3407          return;
3408
3409       elsif Present (Component_Items (Comp_List)) then
3410          Comp_Item := First (Component_Items (Comp_List));
3411
3412       else
3413          Comp_Item := Empty;
3414       end if;
3415
3416       while Present (Comp_Item) loop
3417
3418          --  Skip the tag of a tagged record, the interface tags, as well
3419          --  as all items that are not user components (anonymous types,
3420          --  rep clauses, Parent field, controller field).
3421
3422          if Nkind (Comp_Item) = N_Component_Declaration then
3423             declare
3424                Comp : constant Entity_Id := Defining_Identifier (Comp_Item);
3425             begin
3426                if not Is_Tag (Comp)
3427                  and then Chars (Comp) /= Name_uParent
3428                  and then Chars (Comp) /= Name_uController
3429                then
3430                   Append_Elmt (Comp, Into);
3431                end if;
3432             end;
3433          end if;
3434
3435          Next (Comp_Item);
3436       end loop;
3437
3438       if No (Variant_Part (Comp_List)) then
3439          return;
3440       else
3441          Discrim_Name := Name (Variant_Part (Comp_List));
3442          Variant := First_Non_Pragma (Variants (Variant_Part (Comp_List)));
3443       end if;
3444
3445       --  Look for the discriminant that governs this variant part.
3446       --  The discriminant *must* be in the Governed_By List
3447
3448       Assoc := First (Governed_By);
3449       Find_Constraint : loop
3450          Discrim := First (Choices (Assoc));
3451          exit Find_Constraint when Chars (Discrim_Name) = Chars (Discrim)
3452            or else (Present (Corresponding_Discriminant (Entity (Discrim)))
3453                       and then
3454                     Chars (Corresponding_Discriminant (Entity (Discrim)))
3455                          = Chars  (Discrim_Name))
3456            or else Chars (Original_Record_Component (Entity (Discrim)))
3457                          = Chars (Discrim_Name);
3458
3459          if No (Next (Assoc)) then
3460             if not Is_Constrained (Typ)
3461               and then Is_Derived_Type (Typ)
3462               and then Present (Stored_Constraint (Typ))
3463             then
3464                --  If the type is a tagged type with inherited discriminants,
3465                --  use the stored constraint on the parent in order to find
3466                --  the values of discriminants that are otherwise hidden by an
3467                --  explicit constraint. Renamed discriminants are handled in
3468                --  the code above.
3469
3470                --  If several parent discriminants are renamed by a single
3471                --  discriminant of the derived type, the call to obtain the
3472                --  Corresponding_Discriminant field only retrieves the last
3473                --  of them. We recover the constraint on the others from the
3474                --  Stored_Constraint as well.
3475
3476                declare
3477                   D : Entity_Id;
3478                   C : Elmt_Id;
3479
3480                begin
3481                   D := First_Discriminant (Etype (Typ));
3482                   C := First_Elmt (Stored_Constraint (Typ));
3483                   while Present (D) and then Present (C) loop
3484                      if Chars (Discrim_Name) = Chars (D) then
3485                         if Is_Entity_Name (Node (C))
3486                           and then Entity (Node (C)) = Entity (Discrim)
3487                         then
3488                            --  D is renamed by Discrim, whose value is given in
3489                            --  Assoc.
3490
3491                            null;
3492
3493                         else
3494                            Assoc :=
3495                              Make_Component_Association (Sloc (Typ),
3496                                New_List
3497                                  (New_Occurrence_Of (D, Sloc (Typ))),
3498                                   Duplicate_Subexpr_No_Checks (Node (C)));
3499                         end if;
3500                         exit Find_Constraint;
3501                      end if;
3502
3503                      Next_Discriminant (D);
3504                      Next_Elmt (C);
3505                   end loop;
3506                end;
3507             end if;
3508          end if;
3509
3510          if No (Next (Assoc)) then
3511             Error_Msg_NE (" missing value for discriminant&",
3512               First (Governed_By), Discrim_Name);
3513             Report_Errors := True;
3514             return;
3515          end if;
3516
3517          Next (Assoc);
3518       end loop Find_Constraint;
3519
3520       Discrim_Value := Expression (Assoc);
3521
3522       if not Is_OK_Static_Expression (Discrim_Value) then
3523          Error_Msg_FE
3524            ("value for discriminant & must be static!",
3525             Discrim_Value, Discrim);
3526          Why_Not_Static (Discrim_Value);
3527          Report_Errors := True;
3528          return;
3529       end if;
3530
3531       Search_For_Discriminant_Value : declare
3532          Low  : Node_Id;
3533          High : Node_Id;
3534
3535          UI_High          : Uint;
3536          UI_Low           : Uint;
3537          UI_Discrim_Value : constant Uint := Expr_Value (Discrim_Value);
3538
3539       begin
3540          Find_Discrete_Value : while Present (Variant) loop
3541             Discrete_Choice := First (Discrete_Choices (Variant));
3542             while Present (Discrete_Choice) loop
3543
3544                exit Find_Discrete_Value when
3545                  Nkind (Discrete_Choice) = N_Others_Choice;
3546
3547                Get_Index_Bounds (Discrete_Choice, Low, High);
3548
3549                UI_Low  := Expr_Value (Low);
3550                UI_High := Expr_Value (High);
3551
3552                exit Find_Discrete_Value when
3553                  UI_Low <= UI_Discrim_Value
3554                    and then
3555                  UI_High >= UI_Discrim_Value;
3556
3557                Next (Discrete_Choice);
3558             end loop;
3559
3560             Next_Non_Pragma (Variant);
3561          end loop Find_Discrete_Value;
3562       end Search_For_Discriminant_Value;
3563
3564       if No (Variant) then
3565          Error_Msg_NE
3566            ("value of discriminant & is out of range", Discrim_Value, Discrim);
3567          Report_Errors := True;
3568          return;
3569       end  if;
3570
3571       --  If we have found the corresponding choice, recursively add its
3572       --  components to the Into list.
3573
3574       Gather_Components (Empty,
3575         Component_List (Variant), Governed_By, Into, Report_Errors);
3576    end Gather_Components;
3577
3578    ------------------------
3579    -- Get_Actual_Subtype --
3580    ------------------------
3581
3582    function Get_Actual_Subtype (N : Node_Id) return Entity_Id is
3583       Typ  : constant Entity_Id := Etype (N);
3584       Utyp : Entity_Id := Underlying_Type (Typ);
3585       Decl : Node_Id;
3586       Atyp : Entity_Id;
3587
3588    begin
3589       if No (Utyp) then
3590          Utyp := Typ;
3591       end if;
3592
3593       --  If what we have is an identifier that references a subprogram
3594       --  formal, or a variable or constant object, then we get the actual
3595       --  subtype from the referenced entity if one has been built.
3596
3597       if Nkind (N) = N_Identifier
3598         and then
3599           (Is_Formal (Entity (N))
3600             or else Ekind (Entity (N)) = E_Constant
3601             or else Ekind (Entity (N)) = E_Variable)
3602         and then Present (Actual_Subtype (Entity (N)))
3603       then
3604          return Actual_Subtype (Entity (N));
3605
3606       --  Actual subtype of unchecked union is always itself. We never need
3607       --  the "real" actual subtype. If we did, we couldn't get it anyway
3608       --  because the discriminant is not available. The restrictions on
3609       --  Unchecked_Union are designed to make sure that this is OK.
3610
3611       elsif Is_Unchecked_Union (Base_Type (Utyp)) then
3612          return Typ;
3613
3614       --  Here for the unconstrained case, we must find actual subtype
3615       --  No actual subtype is available, so we must build it on the fly.
3616
3617       --  Checking the type, not the underlying type, for constrainedness
3618       --  seems to be necessary. Maybe all the tests should be on the type???
3619
3620       elsif (not Is_Constrained (Typ))
3621            and then (Is_Array_Type (Utyp)
3622                       or else (Is_Record_Type (Utyp)
3623                                 and then Has_Discriminants (Utyp)))
3624            and then not Has_Unknown_Discriminants (Utyp)
3625            and then not (Ekind (Utyp) = E_String_Literal_Subtype)
3626       then
3627          --  Nothing to do if in spec expression (why not???)
3628
3629          if In_Spec_Expression then
3630             return Typ;
3631
3632          elsif Is_Private_Type (Typ)
3633            and then not Has_Discriminants (Typ)
3634          then
3635             --  If the type has no discriminants, there is no subtype to
3636             --  build, even if the underlying type is discriminated.
3637
3638             return Typ;
3639
3640          --  Else build the actual subtype
3641
3642          else
3643             Decl := Build_Actual_Subtype (Typ, N);
3644             Atyp := Defining_Identifier (Decl);
3645
3646             --  If Build_Actual_Subtype generated a new declaration then use it
3647
3648             if Atyp /= Typ then
3649
3650                --  The actual subtype is an Itype, so analyze the declaration,
3651                --  but do not attach it to the tree, to get the type defined.
3652
3653                Set_Parent (Decl, N);
3654                Set_Is_Itype (Atyp);
3655                Analyze (Decl, Suppress => All_Checks);
3656                Set_Associated_Node_For_Itype (Atyp, N);
3657                Set_Has_Delayed_Freeze (Atyp, False);
3658
3659                --  We need to freeze the actual subtype immediately. This is
3660                --  needed, because otherwise this Itype will not get frozen
3661                --  at all, and it is always safe to freeze on creation because
3662                --  any associated types must be frozen at this point.
3663
3664                Freeze_Itype (Atyp, N);
3665                return Atyp;
3666
3667             --  Otherwise we did not build a declaration, so return original
3668
3669             else
3670                return Typ;
3671             end if;
3672          end if;
3673
3674       --  For all remaining cases, the actual subtype is the same as
3675       --  the nominal type.
3676
3677       else
3678          return Typ;
3679       end if;
3680    end Get_Actual_Subtype;
3681
3682    -------------------------------------
3683    -- Get_Actual_Subtype_If_Available --
3684    -------------------------------------
3685
3686    function Get_Actual_Subtype_If_Available (N : Node_Id) return Entity_Id is
3687       Typ  : constant Entity_Id := Etype (N);
3688
3689    begin
3690       --  If what we have is an identifier that references a subprogram
3691       --  formal, or a variable or constant object, then we get the actual
3692       --  subtype from the referenced entity if one has been built.
3693
3694       if Nkind (N) = N_Identifier
3695         and then
3696           (Is_Formal (Entity (N))
3697             or else Ekind (Entity (N)) = E_Constant
3698             or else Ekind (Entity (N)) = E_Variable)
3699         and then Present (Actual_Subtype (Entity (N)))
3700       then
3701          return Actual_Subtype (Entity (N));
3702
3703       --  Otherwise the Etype of N is returned unchanged
3704
3705       else
3706          return Typ;
3707       end if;
3708    end Get_Actual_Subtype_If_Available;
3709
3710    -------------------------------
3711    -- Get_Default_External_Name --
3712    -------------------------------
3713
3714    function Get_Default_External_Name (E : Node_Or_Entity_Id) return Node_Id is
3715    begin
3716       Get_Decoded_Name_String (Chars (E));
3717
3718       if Opt.External_Name_Imp_Casing = Uppercase then
3719          Set_Casing (All_Upper_Case);
3720       else
3721          Set_Casing (All_Lower_Case);
3722       end if;
3723
3724       return
3725         Make_String_Literal (Sloc (E),
3726           Strval => String_From_Name_Buffer);
3727    end Get_Default_External_Name;
3728
3729    ---------------------------
3730    -- Get_Enum_Lit_From_Pos --
3731    ---------------------------
3732
3733    function Get_Enum_Lit_From_Pos
3734      (T   : Entity_Id;
3735       Pos : Uint;
3736       Loc : Source_Ptr) return Node_Id
3737    is
3738       Lit : Node_Id;
3739
3740    begin
3741       --  In the case where the literal is of type Character, Wide_Character
3742       --  or Wide_Wide_Character or of a type derived from them, there needs
3743       --  to be some special handling since there is no explicit chain of
3744       --  literals to search. Instead, an N_Character_Literal node is created
3745       --  with the appropriate Char_Code and Chars fields.
3746
3747       if Is_Standard_Character_Type (T) then
3748          Set_Character_Literal_Name (UI_To_CC (Pos));
3749          return
3750            Make_Character_Literal (Loc,
3751              Chars              => Name_Find,
3752              Char_Literal_Value => Pos);
3753
3754       --  For all other cases, we have a complete table of literals, and
3755       --  we simply iterate through the chain of literal until the one
3756       --  with the desired position value is found.
3757       --
3758
3759       else
3760          Lit := First_Literal (Base_Type (T));
3761          for J in 1 .. UI_To_Int (Pos) loop
3762             Next_Literal (Lit);
3763          end loop;
3764
3765          return New_Occurrence_Of (Lit, Loc);
3766       end if;
3767    end Get_Enum_Lit_From_Pos;
3768
3769    ------------------------
3770    -- Get_Generic_Entity --
3771    ------------------------
3772
3773    function Get_Generic_Entity (N : Node_Id) return Entity_Id is
3774       Ent : constant Entity_Id := Entity (Name (N));
3775    begin
3776       if Present (Renamed_Object (Ent)) then
3777          return Renamed_Object (Ent);
3778       else
3779          return Ent;
3780       end if;
3781    end Get_Generic_Entity;
3782
3783    ----------------------
3784    -- Get_Index_Bounds --
3785    ----------------------
3786
3787    procedure Get_Index_Bounds (N : Node_Id; L, H : out Node_Id) is
3788       Kind : constant Node_Kind := Nkind (N);
3789       R    : Node_Id;
3790
3791    begin
3792       if Kind = N_Range then
3793          L := Low_Bound (N);
3794          H := High_Bound (N);
3795
3796       elsif Kind = N_Subtype_Indication then
3797          R := Range_Expression (Constraint (N));
3798
3799          if R = Error then
3800             L := Error;
3801             H := Error;
3802             return;
3803
3804          else
3805             L := Low_Bound  (Range_Expression (Constraint (N)));
3806             H := High_Bound (Range_Expression (Constraint (N)));
3807          end if;
3808
3809       elsif Is_Entity_Name (N) and then Is_Type (Entity (N)) then
3810          if Error_Posted (Scalar_Range (Entity (N))) then
3811             L := Error;
3812             H := Error;
3813
3814          elsif Nkind (Scalar_Range (Entity (N))) = N_Subtype_Indication then
3815             Get_Index_Bounds (Scalar_Range (Entity (N)), L, H);
3816
3817          else
3818             L := Low_Bound  (Scalar_Range (Entity (N)));
3819             H := High_Bound (Scalar_Range (Entity (N)));
3820          end if;
3821
3822       else
3823          --  N is an expression, indicating a range with one value
3824
3825          L := N;
3826          H := N;
3827       end if;
3828    end Get_Index_Bounds;
3829
3830    ----------------------------------
3831    -- Get_Library_Unit_Name_string --
3832    ----------------------------------
3833
3834    procedure Get_Library_Unit_Name_String (Decl_Node : Node_Id) is
3835       Unit_Name_Id : constant Unit_Name_Type := Get_Unit_Name (Decl_Node);
3836
3837    begin
3838       Get_Unit_Name_String (Unit_Name_Id);
3839
3840       --  Remove seven last character (" (spec)" or " (body)")
3841
3842       Name_Len := Name_Len - 7;
3843       pragma Assert (Name_Buffer (Name_Len + 1) = ' ');
3844    end Get_Library_Unit_Name_String;
3845
3846    ------------------------
3847    -- Get_Name_Entity_Id --
3848    ------------------------
3849
3850    function Get_Name_Entity_Id (Id : Name_Id) return Entity_Id is
3851    begin
3852       return Entity_Id (Get_Name_Table_Info (Id));
3853    end Get_Name_Entity_Id;
3854
3855    -------------------
3856    -- Get_Pragma_Id --
3857    -------------------
3858
3859    function Get_Pragma_Id (N : Node_Id) return Pragma_Id is
3860    begin
3861       return Get_Pragma_Id (Pragma_Name (N));
3862    end Get_Pragma_Id;
3863
3864    ---------------------------
3865    -- Get_Referenced_Object --
3866    ---------------------------
3867
3868    function Get_Referenced_Object (N : Node_Id) return Node_Id is
3869       R : Node_Id;
3870
3871    begin
3872       R := N;
3873       while Is_Entity_Name (R)
3874         and then Present (Renamed_Object (Entity (R)))
3875       loop
3876          R := Renamed_Object (Entity (R));
3877       end loop;
3878
3879       return R;
3880    end Get_Referenced_Object;
3881
3882    ------------------------
3883    -- Get_Renamed_Entity --
3884    ------------------------
3885
3886    function Get_Renamed_Entity (E : Entity_Id) return Entity_Id is
3887       R : Entity_Id;
3888
3889    begin
3890       R := E;
3891       while Present (Renamed_Entity (R)) loop
3892          R := Renamed_Entity (R);
3893       end loop;
3894
3895       return R;
3896    end Get_Renamed_Entity;
3897
3898    -------------------------
3899    -- Get_Subprogram_Body --
3900    -------------------------
3901
3902    function Get_Subprogram_Body (E : Entity_Id) return Node_Id is
3903       Decl : Node_Id;
3904
3905    begin
3906       Decl := Unit_Declaration_Node (E);
3907
3908       if Nkind (Decl) = N_Subprogram_Body then
3909          return Decl;
3910
3911       --  The below comment is bad, because it is possible for
3912       --  Nkind (Decl) to be an N_Subprogram_Body_Stub ???
3913
3914       else           --  Nkind (Decl) = N_Subprogram_Declaration
3915
3916          if Present (Corresponding_Body (Decl)) then
3917             return Unit_Declaration_Node (Corresponding_Body (Decl));
3918
3919          --  Imported subprogram case
3920
3921          else
3922             return Empty;
3923          end if;
3924       end if;
3925    end Get_Subprogram_Body;
3926
3927    ---------------------------
3928    -- Get_Subprogram_Entity --
3929    ---------------------------
3930
3931    function Get_Subprogram_Entity (Nod : Node_Id) return Entity_Id is
3932       Nam  : Node_Id;
3933       Proc : Entity_Id;
3934
3935    begin
3936       if Nkind (Nod) = N_Accept_Statement then
3937          Nam := Entry_Direct_Name (Nod);
3938
3939       --  For an entry call, the prefix of the call is a selected component.
3940       --  Need additional code for internal calls ???
3941
3942       elsif Nkind (Nod) = N_Entry_Call_Statement then
3943          if Nkind (Name (Nod)) = N_Selected_Component then
3944             Nam := Entity (Selector_Name (Name (Nod)));
3945          else
3946             Nam := Empty;
3947          end if;
3948
3949       else
3950          Nam := Name (Nod);
3951       end if;
3952
3953       if Nkind (Nam) = N_Explicit_Dereference then
3954          Proc := Etype (Prefix (Nam));
3955       elsif Is_Entity_Name (Nam) then
3956          Proc := Entity (Nam);
3957       else
3958          return Empty;
3959       end if;
3960
3961       if Is_Object (Proc) then
3962          Proc := Etype (Proc);
3963       end if;
3964
3965       if Ekind (Proc) = E_Access_Subprogram_Type then
3966          Proc := Directly_Designated_Type (Proc);
3967       end if;
3968
3969       if not Is_Subprogram (Proc)
3970         and then Ekind (Proc) /= E_Subprogram_Type
3971       then
3972          return Empty;
3973       else
3974          return Proc;
3975       end if;
3976    end Get_Subprogram_Entity;
3977
3978    -----------------------------
3979    -- Get_Task_Body_Procedure --
3980    -----------------------------
3981
3982    function Get_Task_Body_Procedure (E : Entity_Id) return Node_Id is
3983    begin
3984       --  Note: A task type may be the completion of a private type with
3985       --  discriminants. When performing elaboration checks on a task
3986       --  declaration, the current view of the type may be the private one,
3987       --  and the procedure that holds the body of the task is held in its
3988       --  underlying type.
3989
3990       --  This is an odd function, why not have Task_Body_Procedure do
3991       --  the following digging???
3992
3993       return Task_Body_Procedure (Underlying_Type (Root_Type (E)));
3994    end Get_Task_Body_Procedure;
3995
3996    -----------------------
3997    -- Has_Access_Values --
3998    -----------------------
3999
4000    function Has_Access_Values (T : Entity_Id) return Boolean is
4001       Typ : constant Entity_Id := Underlying_Type (T);
4002
4003    begin
4004       --  Case of a private type which is not completed yet. This can only
4005       --  happen in the case of a generic format type appearing directly, or
4006       --  as a component of the type to which this function is being applied
4007       --  at the top level. Return False in this case, since we certainly do
4008       --  not know that the type contains access types.
4009
4010       if No (Typ) then
4011          return False;
4012
4013       elsif Is_Access_Type (Typ) then
4014          return True;
4015
4016       elsif Is_Array_Type (Typ) then
4017          return Has_Access_Values (Component_Type (Typ));
4018
4019       elsif Is_Record_Type (Typ) then
4020          declare
4021             Comp : Entity_Id;
4022
4023          begin
4024             --  Loop to Check components
4025
4026             Comp := First_Component_Or_Discriminant (Typ);
4027             while Present (Comp) loop
4028
4029                --  Check for access component, tag field does not count, even
4030                --  though it is implemented internally using an access type.
4031
4032                if Has_Access_Values (Etype (Comp))
4033                  and then Chars (Comp) /= Name_uTag
4034                then
4035                   return True;
4036                end if;
4037
4038                Next_Component_Or_Discriminant (Comp);
4039             end loop;
4040          end;
4041
4042          return False;
4043
4044       else
4045          return False;
4046       end if;
4047    end Has_Access_Values;
4048
4049    ------------------------------
4050    -- Has_Compatible_Alignment --
4051    ------------------------------
4052
4053    function Has_Compatible_Alignment
4054      (Obj  : Entity_Id;
4055       Expr : Node_Id) return Alignment_Result
4056    is
4057       function Has_Compatible_Alignment_Internal
4058         (Obj     : Entity_Id;
4059          Expr    : Node_Id;
4060          Default : Alignment_Result) return Alignment_Result;
4061       --  This is the internal recursive function that actually does the work.
4062       --  There is one additional parameter, which says what the result should
4063       --  be if no alignment information is found, and there is no definite
4064       --  indication of compatible alignments. At the outer level, this is set
4065       --  to Unknown, but for internal recursive calls in the case where types
4066       --  are known to be correct, it is set to Known_Compatible.
4067
4068       ---------------------------------------
4069       -- Has_Compatible_Alignment_Internal --
4070       ---------------------------------------
4071
4072       function Has_Compatible_Alignment_Internal
4073         (Obj     : Entity_Id;
4074          Expr    : Node_Id;
4075          Default : Alignment_Result) return Alignment_Result
4076       is
4077          Result : Alignment_Result := Known_Compatible;
4078          --  Holds the current status of the result. Note that once a value of
4079          --  Known_Incompatible is set, it is sticky and does not get changed
4080          --  to Unknown (the value in Result only gets worse as we go along,
4081          --  never better).
4082
4083          Offs : Uint := No_Uint;
4084          --  Set to a factor of the offset from the base object when Expr is a
4085          --  selected or indexed component, based on Component_Bit_Offset and
4086          --  Component_Size respectively. A negative value is used to represent
4087          --  a value which is not known at compile time.
4088
4089          procedure Check_Prefix;
4090          --  Checks the prefix recursively in the case where the expression
4091          --  is an indexed or selected component.
4092
4093          procedure Set_Result (R : Alignment_Result);
4094          --  If R represents a worse outcome (unknown instead of known
4095          --  compatible, or known incompatible), then set Result to R.
4096
4097          ------------------
4098          -- Check_Prefix --
4099          ------------------
4100
4101          procedure Check_Prefix is
4102          begin
4103             --  The subtlety here is that in doing a recursive call to check
4104             --  the prefix, we have to decide what to do in the case where we
4105             --  don't find any specific indication of an alignment problem.
4106
4107             --  At the outer level, we normally set Unknown as the result in
4108             --  this case, since we can only set Known_Compatible if we really
4109             --  know that the alignment value is OK, but for the recursive
4110             --  call, in the case where the types match, and we have not
4111             --  specified a peculiar alignment for the object, we are only
4112             --  concerned about suspicious rep clauses, the default case does
4113             --  not affect us, since the compiler will, in the absence of such
4114             --  rep clauses, ensure that the alignment is correct.
4115
4116             if Default = Known_Compatible
4117               or else
4118                 (Etype (Obj) = Etype (Expr)
4119                   and then (Unknown_Alignment (Obj)
4120                              or else
4121                                Alignment (Obj) = Alignment (Etype (Obj))))
4122             then
4123                Set_Result
4124                  (Has_Compatible_Alignment_Internal
4125                     (Obj, Prefix (Expr), Known_Compatible));
4126
4127             --  In all other cases, we need a full check on the prefix
4128
4129             else
4130                Set_Result
4131                  (Has_Compatible_Alignment_Internal
4132                     (Obj, Prefix (Expr), Unknown));
4133             end if;
4134          end Check_Prefix;
4135
4136          ----------------
4137          -- Set_Result --
4138          ----------------
4139
4140          procedure Set_Result (R : Alignment_Result) is
4141          begin
4142             if R > Result then
4143                Result := R;
4144             end if;
4145          end Set_Result;
4146
4147       --  Start of processing for Has_Compatible_Alignment_Internal
4148
4149       begin
4150          --  If Expr is a selected component, we must make sure there is no
4151          --  potentially troublesome component clause, and that the record is
4152          --  not packed.
4153
4154          if Nkind (Expr) = N_Selected_Component then
4155
4156             --  Packed record always generate unknown alignment
4157
4158             if Is_Packed (Etype (Prefix (Expr))) then
4159                Set_Result (Unknown);
4160             end if;
4161
4162             --  Check prefix and component offset
4163
4164             Check_Prefix;
4165             Offs := Component_Bit_Offset (Entity (Selector_Name (Expr)));
4166
4167          --  If Expr is an indexed component, we must make sure there is no
4168          --  potentially troublesome Component_Size clause and that the array
4169          --  is not bit-packed.
4170
4171          elsif Nkind (Expr) = N_Indexed_Component then
4172             declare
4173                Typ : constant Entity_Id := Etype (Prefix (Expr));
4174                Ind : constant Node_Id   := First_Index (Typ);
4175
4176             begin
4177                --  Bit packed array always generates unknown alignment
4178
4179                if Is_Bit_Packed_Array (Typ) then
4180                   Set_Result (Unknown);
4181                end if;
4182
4183                --  Check prefix and component offset
4184
4185                Check_Prefix;
4186                Offs := Component_Size (Typ);
4187
4188                --  Small optimization: compute the full offset when possible
4189
4190                if Offs /= No_Uint
4191                  and then Offs > Uint_0
4192                  and then Present (Ind)
4193                  and then Nkind (Ind) = N_Range
4194                  and then Compile_Time_Known_Value (Low_Bound (Ind))
4195                  and then Compile_Time_Known_Value (First (Expressions (Expr)))
4196                then
4197                   Offs := Offs * (Expr_Value (First (Expressions (Expr)))
4198                                     - Expr_Value (Low_Bound ((Ind))));
4199                end if;
4200             end;
4201          end if;
4202
4203          --  If we have a null offset, the result is entirely determined by
4204          --  the base object and has already been computed recursively.
4205
4206          if Offs = Uint_0 then
4207             null;
4208
4209          --  Case where we know the alignment of the object
4210
4211          elsif Known_Alignment (Obj) then
4212             declare
4213                ObjA : constant Uint := Alignment (Obj);
4214                ExpA : Uint          := No_Uint;
4215                SizA : Uint          := No_Uint;
4216
4217             begin
4218                --  If alignment of Obj is 1, then we are always OK
4219
4220                if ObjA = 1 then
4221                   Set_Result (Known_Compatible);
4222
4223                --  Alignment of Obj is greater than 1, so we need to check
4224
4225                else
4226                   --  If we have an offset, see if it is compatible
4227
4228                   if Offs /= No_Uint and Offs > Uint_0 then
4229                      if Offs mod (System_Storage_Unit * ObjA) /= 0 then
4230                         Set_Result (Known_Incompatible);
4231                      end if;
4232
4233                      --  See if Expr is an object with known alignment
4234
4235                   elsif Is_Entity_Name (Expr)
4236                     and then Known_Alignment (Entity (Expr))
4237                   then
4238                      ExpA := Alignment (Entity (Expr));
4239
4240                      --  Otherwise, we can use the alignment of the type of
4241                      --  Expr given that we already checked for
4242                      --  discombobulating rep clauses for the cases of indexed
4243                      --  and selected components above.
4244
4245                   elsif Known_Alignment (Etype (Expr)) then
4246                      ExpA := Alignment (Etype (Expr));
4247
4248                      --  Otherwise the alignment is unknown
4249
4250                   else
4251                      Set_Result (Default);
4252                   end if;
4253
4254                   --  If we got an alignment, see if it is acceptable
4255
4256                   if ExpA /= No_Uint and then ExpA < ObjA then
4257                      Set_Result (Known_Incompatible);
4258                   end if;
4259
4260                   --  If Expr is not a piece of a larger object, see if size
4261                   --  is given. If so, check that it is not too small for the
4262                   --  required alignment.
4263
4264                   if Offs /= No_Uint then
4265                      null;
4266
4267                      --  See if Expr is an object with known size
4268
4269                   elsif Is_Entity_Name (Expr)
4270                     and then Known_Static_Esize (Entity (Expr))
4271                   then
4272                      SizA := Esize (Entity (Expr));
4273
4274                      --  Otherwise, we check the object size of the Expr type
4275
4276                   elsif Known_Static_Esize (Etype (Expr)) then
4277                      SizA := Esize (Etype (Expr));
4278                   end if;
4279
4280                   --  If we got a size, see if it is a multiple of the Obj
4281                   --  alignment, if not, then the alignment cannot be
4282                   --  acceptable, since the size is always a multiple of the
4283                   --  alignment.
4284
4285                   if SizA /= No_Uint then
4286                      if SizA mod (ObjA * Ttypes.System_Storage_Unit) /= 0 then
4287                         Set_Result (Known_Incompatible);
4288                      end if;
4289                   end if;
4290                end if;
4291             end;
4292
4293          --  If we do not know required alignment, any non-zero offset is a
4294          --  potential problem (but certainly may be OK, so result is unknown).
4295
4296          elsif Offs /= No_Uint then
4297             Set_Result (Unknown);
4298
4299          --  If we can't find the result by direct comparison of alignment
4300          --  values, then there is still one case that we can determine known
4301          --  result, and that is when we can determine that the types are the
4302          --  same, and no alignments are specified. Then we known that the
4303          --  alignments are compatible, even if we don't know the alignment
4304          --  value in the front end.
4305
4306          elsif Etype (Obj) = Etype (Expr) then
4307
4308             --  Types are the same, but we have to check for possible size
4309             --  and alignments on the Expr object that may make the alignment
4310             --  different, even though the types are the same.
4311
4312             if Is_Entity_Name (Expr) then
4313
4314                --  First check alignment of the Expr object. Any alignment less
4315                --  than Maximum_Alignment is worrisome since this is the case
4316                --  where we do not know the alignment of Obj.
4317
4318                if Known_Alignment (Entity (Expr))
4319                  and then
4320                    UI_To_Int (Alignment (Entity (Expr))) <
4321                                                     Ttypes.Maximum_Alignment
4322                then
4323                   Set_Result (Unknown);
4324
4325                   --  Now check size of Expr object. Any size that is not an
4326                   --  even multiple of Maximum_Alignment is also worrisome
4327                   --  since it may cause the alignment of the object to be less
4328                   --  than the alignment of the type.
4329
4330                elsif Known_Static_Esize (Entity (Expr))
4331                  and then
4332                    (UI_To_Int (Esize (Entity (Expr))) mod
4333                      (Ttypes.Maximum_Alignment * Ttypes.System_Storage_Unit))
4334                                                                         /= 0
4335                then
4336                   Set_Result (Unknown);
4337
4338                   --  Otherwise same type is decisive
4339
4340                else
4341                   Set_Result (Known_Compatible);
4342                end if;
4343             end if;
4344
4345          --  Another case to deal with is when there is an explicit size or
4346          --  alignment clause when the types are not the same. If so, then the
4347          --  result is Unknown. We don't need to do this test if the Default is
4348          --  Unknown, since that result will be set in any case.
4349
4350          elsif Default /= Unknown
4351            and then (Has_Size_Clause      (Etype (Expr))
4352                       or else
4353                      Has_Alignment_Clause (Etype (Expr)))
4354          then
4355             Set_Result (Unknown);
4356
4357          --  If no indication found, set default
4358
4359          else
4360             Set_Result (Default);
4361          end if;
4362
4363          --  Return worst result found
4364
4365          return Result;
4366       end Has_Compatible_Alignment_Internal;
4367
4368    --  Start of processing for Has_Compatible_Alignment
4369
4370    begin
4371       --  If Obj has no specified alignment, then set alignment from the type
4372       --  alignment. Perhaps we should always do this, but for sure we should
4373       --  do it when there is an address clause since we can do more if the
4374       --  alignment is known.
4375
4376       if Unknown_Alignment (Obj) then
4377          Set_Alignment (Obj, Alignment (Etype (Obj)));
4378       end if;
4379
4380       --  Now do the internal call that does all the work
4381
4382       return Has_Compatible_Alignment_Internal (Obj, Expr, Unknown);
4383    end Has_Compatible_Alignment;
4384
4385    ----------------------
4386    -- Has_Declarations --
4387    ----------------------
4388
4389    function Has_Declarations (N : Node_Id) return Boolean is
4390    begin
4391       return Nkind_In (Nkind (N), N_Accept_Statement,
4392                                   N_Block_Statement,
4393                                   N_Compilation_Unit_Aux,
4394                                   N_Entry_Body,
4395                                   N_Package_Body,
4396                                   N_Protected_Body,
4397                                   N_Subprogram_Body,
4398                                   N_Task_Body,
4399                                   N_Package_Specification);
4400    end Has_Declarations;
4401
4402    -------------------------------------------
4403    -- Has_Discriminant_Dependent_Constraint --
4404    -------------------------------------------
4405
4406    function Has_Discriminant_Dependent_Constraint
4407      (Comp : Entity_Id) return Boolean
4408    is
4409       Comp_Decl  : constant Node_Id := Parent (Comp);
4410       Subt_Indic : constant Node_Id :=
4411                      Subtype_Indication (Component_Definition (Comp_Decl));
4412       Constr     : Node_Id;
4413       Assn       : Node_Id;
4414
4415    begin
4416       if Nkind (Subt_Indic) = N_Subtype_Indication then
4417          Constr := Constraint (Subt_Indic);
4418
4419          if Nkind (Constr) = N_Index_Or_Discriminant_Constraint then
4420             Assn := First (Constraints (Constr));
4421             while Present (Assn) loop
4422                case Nkind (Assn) is
4423                   when N_Subtype_Indication |
4424                        N_Range              |
4425                        N_Identifier
4426                   =>
4427                      if Depends_On_Discriminant (Assn) then
4428                         return True;
4429                      end if;
4430
4431                   when N_Discriminant_Association =>
4432                      if Depends_On_Discriminant (Expression (Assn)) then
4433                         return True;
4434                      end if;
4435
4436                   when others =>
4437                      null;
4438
4439                end case;
4440
4441                Next (Assn);
4442             end loop;
4443          end if;
4444       end if;
4445
4446       return False;
4447    end Has_Discriminant_Dependent_Constraint;
4448
4449    --------------------
4450    -- Has_Infinities --
4451    --------------------
4452
4453    function Has_Infinities (E : Entity_Id) return Boolean is
4454    begin
4455       return
4456         Is_Floating_Point_Type (E)
4457           and then Nkind (Scalar_Range (E)) = N_Range
4458           and then Includes_Infinities (Scalar_Range (E));
4459    end Has_Infinities;
4460
4461    --------------------
4462    -- Has_Interfaces --
4463    --------------------
4464
4465    function Has_Interfaces
4466      (T             : Entity_Id;
4467       Use_Full_View : Boolean := True) return Boolean
4468    is
4469       Typ : Entity_Id;
4470
4471    begin
4472       --  Handle concurrent types
4473
4474       if Is_Concurrent_Type (T) then
4475          Typ := Corresponding_Record_Type (T);
4476       else
4477          Typ := T;
4478       end if;
4479
4480       if not Present (Typ)
4481         or else not Is_Record_Type (Typ)
4482         or else not Is_Tagged_Type (Typ)
4483       then
4484          return False;
4485       end if;
4486
4487       --  Handle private types
4488
4489       if Use_Full_View
4490         and then Present (Full_View (Typ))
4491       then
4492          Typ := Full_View (Typ);
4493       end if;
4494
4495       --  Handle concurrent record types
4496
4497       if Is_Concurrent_Record_Type (Typ)
4498         and then Is_Non_Empty_List (Abstract_Interface_List (Typ))
4499       then
4500          return True;
4501       end if;
4502
4503       loop
4504          if Is_Interface (Typ)
4505            or else
4506              (Is_Record_Type (Typ)
4507                and then Present (Interfaces (Typ))
4508                and then not Is_Empty_Elmt_List (Interfaces (Typ)))
4509          then
4510             return True;
4511          end if;
4512
4513          exit when Etype (Typ) = Typ
4514
4515             --  Handle private types
4516
4517             or else (Present (Full_View (Etype (Typ)))
4518                        and then Full_View (Etype (Typ)) = Typ)
4519
4520             --  Protect the frontend against wrong source with cyclic
4521             --  derivations
4522
4523             or else Etype (Typ) = T;
4524
4525          --  Climb to the ancestor type handling private types
4526
4527          if Present (Full_View (Etype (Typ))) then
4528             Typ := Full_View (Etype (Typ));
4529          else
4530             Typ := Etype (Typ);
4531          end if;
4532       end loop;
4533
4534       return False;
4535    end Has_Interfaces;
4536
4537    ------------------------
4538    -- Has_Null_Exclusion --
4539    ------------------------
4540
4541    function Has_Null_Exclusion (N : Node_Id) return Boolean is
4542    begin
4543       case Nkind (N) is
4544          when N_Access_Definition               |
4545               N_Access_Function_Definition      |
4546               N_Access_Procedure_Definition     |
4547               N_Access_To_Object_Definition     |
4548               N_Allocator                       |
4549               N_Derived_Type_Definition         |
4550               N_Function_Specification          |
4551               N_Subtype_Declaration             =>
4552             return Null_Exclusion_Present (N);
4553
4554          when N_Component_Definition            |
4555               N_Formal_Object_Declaration       |
4556               N_Object_Renaming_Declaration     =>
4557             if Present (Subtype_Mark (N)) then
4558                return Null_Exclusion_Present (N);
4559             else pragma Assert (Present (Access_Definition (N)));
4560                return Null_Exclusion_Present (Access_Definition (N));
4561             end if;
4562
4563          when N_Discriminant_Specification =>
4564             if Nkind (Discriminant_Type (N)) = N_Access_Definition then
4565                return Null_Exclusion_Present (Discriminant_Type (N));
4566             else
4567                return Null_Exclusion_Present (N);
4568             end if;
4569
4570          when N_Object_Declaration =>
4571             if Nkind (Object_Definition (N)) = N_Access_Definition then
4572                return Null_Exclusion_Present (Object_Definition (N));
4573             else
4574                return Null_Exclusion_Present (N);
4575             end if;
4576
4577          when N_Parameter_Specification =>
4578             if Nkind (Parameter_Type (N)) = N_Access_Definition then
4579                return Null_Exclusion_Present (Parameter_Type (N));
4580             else
4581                return Null_Exclusion_Present (N);
4582             end if;
4583
4584          when others =>
4585             return False;
4586
4587       end case;
4588    end Has_Null_Exclusion;
4589
4590    ------------------------
4591    -- Has_Null_Extension --
4592    ------------------------
4593
4594    function Has_Null_Extension (T : Entity_Id) return Boolean is
4595       B     : constant Entity_Id := Base_Type (T);
4596       Comps : Node_Id;
4597       Ext   : Node_Id;
4598
4599    begin
4600       if Nkind (Parent (B)) = N_Full_Type_Declaration
4601         and then Present (Record_Extension_Part (Type_Definition (Parent (B))))
4602       then
4603          Ext := Record_Extension_Part (Type_Definition (Parent (B)));
4604
4605          if Present (Ext) then
4606             if Null_Present (Ext) then
4607                return True;
4608             else
4609                Comps := Component_List (Ext);
4610
4611                --  The null component list is rewritten during analysis to
4612                --  include the parent component. Any other component indicates
4613                --  that the extension was not originally null.
4614
4615                return Null_Present (Comps)
4616                  or else No (Next (First (Component_Items (Comps))));
4617             end if;
4618          else
4619             return False;
4620          end if;
4621
4622       else
4623          return False;
4624       end if;
4625    end Has_Null_Extension;
4626
4627    -------------------------------
4628    -- Has_Overriding_Initialize --
4629    -------------------------------
4630
4631    function Has_Overriding_Initialize (T : Entity_Id) return Boolean is
4632       BT   : constant Entity_Id := Base_Type (T);
4633       Comp : Entity_Id;
4634       P    : Elmt_Id;
4635
4636    begin
4637       if Is_Controlled (BT) then
4638
4639          --  For derived types, check immediate ancestor, excluding
4640          --  Controlled itself.
4641
4642          if Is_Derived_Type (BT)
4643            and then not In_Predefined_Unit (Etype (BT))
4644            and then Has_Overriding_Initialize (Etype (BT))
4645          then
4646             return True;
4647
4648          elsif Present (Primitive_Operations (BT)) then
4649             P := First_Elmt (Primitive_Operations (BT));
4650             while Present (P) loop
4651                if Chars (Node (P)) = Name_Initialize
4652                  and then Comes_From_Source (Node (P))
4653                then
4654                   return True;
4655                end if;
4656
4657                Next_Elmt (P);
4658             end loop;
4659          end if;
4660
4661          return False;
4662
4663       elsif Has_Controlled_Component (BT) then
4664          Comp := First_Component (BT);
4665          while Present (Comp) loop
4666             if Has_Overriding_Initialize (Etype (Comp)) then
4667                return True;
4668             end if;
4669
4670             Next_Component (Comp);
4671          end loop;
4672
4673          return False;
4674
4675       else
4676          return False;
4677       end if;
4678    end Has_Overriding_Initialize;
4679
4680    --------------------------------------
4681    -- Has_Preelaborable_Initialization --
4682    --------------------------------------
4683
4684    function Has_Preelaborable_Initialization (E : Entity_Id) return Boolean is
4685       Has_PE : Boolean;
4686
4687       procedure Check_Components (E : Entity_Id);
4688       --  Check component/discriminant chain, sets Has_PE False if a component
4689       --  or discriminant does not meet the preelaborable initialization rules.
4690
4691       ----------------------
4692       -- Check_Components --
4693       ----------------------
4694
4695       procedure Check_Components (E : Entity_Id) is
4696          Ent : Entity_Id;
4697          Exp : Node_Id;
4698
4699          function Is_Preelaborable_Expression (N : Node_Id) return Boolean;
4700          --  Returns True if and only if the expression denoted by N does not
4701          --  violate restrictions on preelaborable constructs (RM-10.2.1(5-9)).
4702
4703          ---------------------------------
4704          -- Is_Preelaborable_Expression --
4705          ---------------------------------
4706
4707          function Is_Preelaborable_Expression (N : Node_Id) return Boolean is
4708             Exp           : Node_Id;
4709             Assn          : Node_Id;
4710             Choice        : Node_Id;
4711             Comp_Type     : Entity_Id;
4712             Is_Array_Aggr : Boolean;
4713
4714          begin
4715             if Is_Static_Expression (N) then
4716                return True;
4717
4718             elsif Nkind (N) = N_Null then
4719                return True;
4720
4721             --  Attributes are allowed in general, even if their prefix is a
4722             --  formal type. (It seems that certain attributes known not to be
4723             --  static might not be allowed, but there are no rules to prevent
4724             --  them.)
4725
4726             elsif Nkind (N) = N_Attribute_Reference then
4727                return True;
4728
4729             --  The name of a discriminant evaluated within its parent type is
4730             --  defined to be preelaborable (10.2.1(8)). Note that we test for
4731             --  names that denote discriminals as well as discriminants to
4732             --  catch references occurring within init procs.
4733
4734             elsif Is_Entity_Name (N)
4735               and then
4736                 (Ekind (Entity (N)) = E_Discriminant
4737                   or else
4738                     ((Ekind (Entity (N)) = E_Constant
4739                        or else Ekind (Entity (N)) = E_In_Parameter)
4740                      and then Present (Discriminal_Link (Entity (N)))))
4741             then
4742                return True;
4743
4744             elsif Nkind (N) = N_Qualified_Expression then
4745                return Is_Preelaborable_Expression (Expression (N));
4746
4747             --  For aggregates we have to check that each of the associations
4748             --  is preelaborable.
4749
4750             elsif Nkind (N) = N_Aggregate
4751               or else Nkind (N) = N_Extension_Aggregate
4752             then
4753                Is_Array_Aggr := Is_Array_Type (Etype (N));
4754
4755                if Is_Array_Aggr then
4756                   Comp_Type := Component_Type (Etype (N));
4757                end if;
4758
4759                --  Check the ancestor part of extension aggregates, which must
4760                --  be either the name of a type that has preelaborable init or
4761                --  an expression that is preelaborable.
4762
4763                if Nkind (N) = N_Extension_Aggregate then
4764                   declare
4765                      Anc_Part : constant Node_Id := Ancestor_Part (N);
4766
4767                   begin
4768                      if Is_Entity_Name (Anc_Part)
4769                        and then Is_Type (Entity (Anc_Part))
4770                      then
4771                         if not Has_Preelaborable_Initialization
4772                                  (Entity (Anc_Part))
4773                         then
4774                            return False;
4775                         end if;
4776
4777                      elsif not Is_Preelaborable_Expression (Anc_Part) then
4778                         return False;
4779                      end if;
4780                   end;
4781                end if;
4782
4783                --  Check positional associations
4784
4785                Exp := First (Expressions (N));
4786                while Present (Exp) loop
4787                   if not Is_Preelaborable_Expression (Exp) then
4788                      return False;
4789                   end if;
4790
4791                   Next (Exp);
4792                end loop;
4793
4794                --  Check named associations
4795
4796                Assn := First (Component_Associations (N));
4797                while Present (Assn) loop
4798                   Choice := First (Choices (Assn));
4799                   while Present (Choice) loop
4800                      if Is_Array_Aggr then
4801                         if Nkind (Choice) = N_Others_Choice then
4802                            null;
4803
4804                         elsif Nkind (Choice) = N_Range then
4805                            if not Is_Static_Range (Choice) then
4806                               return False;
4807                            end if;
4808
4809                         elsif not Is_Static_Expression (Choice) then
4810                            return False;
4811                         end if;
4812
4813                      else
4814                         Comp_Type := Etype (Choice);
4815                      end if;
4816
4817                      Next (Choice);
4818                   end loop;
4819
4820                   --  If the association has a <> at this point, then we have
4821                   --  to check whether the component's type has preelaborable
4822                   --  initialization. Note that this only occurs when the
4823                   --  association's corresponding component does not have a
4824                   --  default expression, the latter case having already been
4825                   --  expanded as an expression for the association.
4826
4827                   if Box_Present (Assn) then
4828                      if not Has_Preelaborable_Initialization (Comp_Type) then
4829                         return False;
4830                      end if;
4831
4832                   --  In the expression case we check whether the expression
4833                   --  is preelaborable.
4834
4835                   elsif
4836                     not Is_Preelaborable_Expression (Expression (Assn))
4837                   then
4838                      return False;
4839                   end if;
4840
4841                   Next (Assn);
4842                end loop;
4843
4844                --  If we get here then aggregate as a whole is preelaborable
4845
4846                return True;
4847
4848             --  All other cases are not preelaborable
4849
4850             else
4851                return False;
4852             end if;
4853          end Is_Preelaborable_Expression;
4854
4855       --  Start of processing for Check_Components
4856
4857       begin
4858          --  Loop through entities of record or protected type
4859
4860          Ent := E;
4861          while Present (Ent) loop
4862
4863             --  We are interested only in components and discriminants
4864
4865             if Ekind_In (Ent, E_Component, E_Discriminant) then
4866
4867                --  Get default expression if any. If there is no declaration
4868                --  node, it means we have an internal entity. The parent and
4869                --  tag fields are examples of such entities. For these cases,
4870                --  we just test the type of the entity.
4871
4872                if Present (Declaration_Node (Ent)) then
4873                   Exp := Expression (Declaration_Node (Ent));
4874                else
4875                   Exp := Empty;
4876                end if;
4877
4878                --  A component has PI if it has no default expression and the
4879                --  component type has PI.
4880
4881                if No (Exp) then
4882                   if not Has_Preelaborable_Initialization (Etype (Ent)) then
4883                      Has_PE := False;
4884                      exit;
4885                   end if;
4886
4887                --  Require the default expression to be preelaborable
4888
4889                elsif not Is_Preelaborable_Expression (Exp) then
4890                   Has_PE := False;
4891                   exit;
4892                end if;
4893             end if;
4894
4895             Next_Entity (Ent);
4896          end loop;
4897       end Check_Components;
4898
4899    --  Start of processing for Has_Preelaborable_Initialization
4900
4901    begin
4902       --  Immediate return if already marked as known preelaborable init. This
4903       --  covers types for which this function has already been called once
4904       --  and returned True (in which case the result is cached), and also
4905       --  types to which a pragma Preelaborable_Initialization applies.
4906
4907       if Known_To_Have_Preelab_Init (E) then
4908          return True;
4909       end if;
4910
4911       --  If the type is a subtype representing a generic actual type, then
4912       --  test whether its base type has preelaborable initialization since
4913       --  the subtype representing the actual does not inherit this attribute
4914       --  from the actual or formal. (but maybe it should???)
4915
4916       if Is_Generic_Actual_Type (E) then
4917          return Has_Preelaborable_Initialization (Base_Type (E));
4918       end if;
4919
4920       --  All elementary types have preelaborable initialization
4921
4922       if Is_Elementary_Type (E) then
4923          Has_PE := True;
4924
4925       --  Array types have PI if the component type has PI
4926
4927       elsif Is_Array_Type (E) then
4928          Has_PE := Has_Preelaborable_Initialization (Component_Type (E));
4929
4930       --  A derived type has preelaborable initialization if its parent type
4931       --  has preelaborable initialization and (in the case of a derived record
4932       --  extension) if the non-inherited components all have preelaborable
4933       --  initialization. However, a user-defined controlled type with an
4934       --  overriding Initialize procedure does not have preelaborable
4935       --  initialization.
4936
4937       elsif Is_Derived_Type (E) then
4938
4939          --  If the derived type is a private extension then it doesn't have
4940          --  preelaborable initialization.
4941
4942          if Ekind (Base_Type (E)) = E_Record_Type_With_Private then
4943             return False;
4944          end if;
4945
4946          --  First check whether ancestor type has preelaborable initialization
4947
4948          Has_PE := Has_Preelaborable_Initialization (Etype (Base_Type (E)));
4949
4950          --  If OK, check extension components (if any)
4951
4952          if Has_PE and then Is_Record_Type (E) then
4953             Check_Components (First_Entity (E));
4954          end if;
4955
4956          --  Check specifically for 10.2.1(11.4/2) exception: a controlled type
4957          --  with a user defined Initialize procedure does not have PI.
4958
4959          if Has_PE
4960            and then Is_Controlled (E)
4961            and then Has_Overriding_Initialize (E)
4962          then
4963             Has_PE := False;
4964          end if;
4965
4966       --  Private types not derived from a type having preelaborable init and
4967       --  that are not marked with pragma Preelaborable_Initialization do not
4968       --  have preelaborable initialization.
4969
4970       elsif Is_Private_Type (E) then
4971          return False;
4972
4973       --  Record type has PI if it is non private and all components have PI
4974
4975       elsif Is_Record_Type (E) then
4976          Has_PE := True;
4977          Check_Components (First_Entity (E));
4978
4979       --  Protected types must not have entries, and components must meet
4980       --  same set of rules as for record components.
4981
4982       elsif Is_Protected_Type (E) then
4983          if Has_Entries (E) then
4984             Has_PE := False;
4985          else
4986             Has_PE := True;
4987             Check_Components (First_Entity (E));
4988             Check_Components (First_Private_Entity (E));
4989          end if;
4990
4991       --  Type System.Address always has preelaborable initialization
4992
4993       elsif Is_RTE (E, RE_Address) then
4994          Has_PE := True;
4995
4996       --  In all other cases, type does not have preelaborable initialization
4997
4998       else
4999          return False;
5000       end if;
5001
5002       --  If type has preelaborable initialization, cache result
5003
5004       if Has_PE then
5005          Set_Known_To_Have_Preelab_Init (E);
5006       end if;
5007
5008       return Has_PE;
5009    end Has_Preelaborable_Initialization;
5010
5011    ---------------------------
5012    -- Has_Private_Component --
5013    ---------------------------
5014
5015    function Has_Private_Component (Type_Id : Entity_Id) return Boolean is
5016       Btype     : Entity_Id := Base_Type (Type_Id);
5017       Component : Entity_Id;
5018
5019    begin
5020       if Error_Posted (Type_Id)
5021         or else Error_Posted (Btype)
5022       then
5023          return False;
5024       end if;
5025
5026       if Is_Class_Wide_Type (Btype) then
5027          Btype := Root_Type (Btype);
5028       end if;
5029
5030       if Is_Private_Type (Btype) then
5031          declare
5032             UT : constant Entity_Id := Underlying_Type (Btype);
5033          begin
5034             if No (UT) then
5035                if No (Full_View (Btype)) then
5036                   return not Is_Generic_Type (Btype)
5037                     and then not Is_Generic_Type (Root_Type (Btype));
5038                else
5039                   return not Is_Generic_Type (Root_Type (Full_View (Btype)));
5040                end if;
5041             else
5042                return not Is_Frozen (UT) and then Has_Private_Component (UT);
5043             end if;
5044          end;
5045
5046       elsif Is_Array_Type (Btype) then
5047          return Has_Private_Component (Component_Type (Btype));
5048
5049       elsif Is_Record_Type (Btype) then
5050          Component := First_Component (Btype);
5051          while Present (Component) loop
5052             if Has_Private_Component (Etype (Component)) then
5053                return True;
5054             end if;
5055
5056             Next_Component (Component);
5057          end loop;
5058
5059          return False;
5060
5061       elsif Is_Protected_Type (Btype)
5062         and then Present (Corresponding_Record_Type (Btype))
5063       then
5064          return Has_Private_Component (Corresponding_Record_Type (Btype));
5065
5066       else
5067          return False;
5068       end if;
5069    end Has_Private_Component;
5070
5071    ----------------
5072    -- Has_Stream --
5073    ----------------
5074
5075    function Has_Stream (T : Entity_Id) return Boolean is
5076       E : Entity_Id;
5077
5078    begin
5079       if No (T) then
5080          return False;
5081
5082       elsif Is_RTE (Root_Type (T), RE_Root_Stream_Type) then
5083          return True;
5084
5085       elsif Is_Array_Type (T) then
5086          return Has_Stream (Component_Type (T));
5087
5088       elsif Is_Record_Type (T) then
5089          E := First_Component (T);
5090          while Present (E) loop
5091             if Has_Stream (Etype (E)) then
5092                return True;
5093             else
5094                Next_Component (E);
5095             end if;
5096          end loop;
5097
5098          return False;
5099
5100       elsif Is_Private_Type (T) then
5101          return Has_Stream (Underlying_Type (T));
5102
5103       else
5104          return False;
5105       end if;
5106    end Has_Stream;
5107
5108    --------------------------
5109    -- Has_Tagged_Component --
5110    --------------------------
5111
5112    function Has_Tagged_Component (Typ : Entity_Id) return Boolean is
5113       Comp : Entity_Id;
5114
5115    begin
5116       if Is_Private_Type (Typ)
5117         and then Present (Underlying_Type (Typ))
5118       then
5119          return Has_Tagged_Component (Underlying_Type (Typ));
5120
5121       elsif Is_Array_Type (Typ) then
5122          return Has_Tagged_Component (Component_Type (Typ));
5123
5124       elsif Is_Tagged_Type (Typ) then
5125          return True;
5126
5127       elsif Is_Record_Type (Typ) then
5128          Comp := First_Component (Typ);
5129          while Present (Comp) loop
5130             if Has_Tagged_Component (Etype (Comp)) then
5131                return True;
5132             end if;
5133
5134             Next_Component (Comp);
5135          end loop;
5136
5137          return False;
5138
5139       else
5140          return False;
5141       end if;
5142    end Has_Tagged_Component;
5143
5144    --------------------------
5145    -- Implements_Interface --
5146    --------------------------
5147
5148    function Implements_Interface
5149      (Typ_Ent         : Entity_Id;
5150       Iface_Ent       : Entity_Id;
5151       Exclude_Parents : Boolean := False) return Boolean
5152    is
5153       Ifaces_List : Elist_Id;
5154       Elmt        : Elmt_Id;
5155       Iface       : Entity_Id := Base_Type (Iface_Ent);
5156       Typ         : Entity_Id := Base_Type (Typ_Ent);
5157
5158    begin
5159       if Is_Class_Wide_Type (Typ) then
5160          Typ := Root_Type (Typ);
5161       end if;
5162
5163       if not Has_Interfaces (Typ) then
5164          return False;
5165       end if;
5166
5167       if Is_Class_Wide_Type (Iface) then
5168          Iface := Root_Type (Iface);
5169       end if;
5170
5171       Collect_Interfaces (Typ, Ifaces_List);
5172
5173       Elmt := First_Elmt (Ifaces_List);
5174       while Present (Elmt) loop
5175          if Is_Ancestor (Node (Elmt), Typ)
5176            and then Exclude_Parents
5177          then
5178             null;
5179
5180          elsif Node (Elmt) = Iface then
5181             return True;
5182          end if;
5183
5184          Next_Elmt (Elmt);
5185       end loop;
5186
5187       return False;
5188    end Implements_Interface;
5189
5190    -----------------
5191    -- In_Instance --
5192    -----------------
5193
5194    function In_Instance return Boolean is
5195       Curr_Unit : constant Entity_Id := Cunit_Entity (Current_Sem_Unit);
5196       S         : Entity_Id;
5197
5198    begin
5199       S := Current_Scope;
5200       while Present (S)
5201         and then S /= Standard_Standard
5202       loop
5203          if (Ekind (S) = E_Function
5204               or else Ekind (S) = E_Package
5205               or else Ekind (S) = E_Procedure)
5206            and then Is_Generic_Instance (S)
5207          then
5208             --  A child instance is always compiled in the context of a parent
5209             --  instance. Nevertheless, the actuals are not analyzed in an
5210             --  instance context. We detect this case by examining the current
5211             --  compilation unit, which must be a child instance, and checking
5212             --  that it is not currently on the scope stack.
5213
5214             if Is_Child_Unit (Curr_Unit)
5215               and then
5216                 Nkind (Unit (Cunit (Current_Sem_Unit)))
5217                   = N_Package_Instantiation
5218               and then not In_Open_Scopes (Curr_Unit)
5219             then
5220                return False;
5221             else
5222                return True;
5223             end if;
5224          end if;
5225
5226          S := Scope (S);
5227       end loop;
5228
5229       return False;
5230    end In_Instance;
5231
5232    ----------------------
5233    -- In_Instance_Body --
5234    ----------------------
5235
5236    function In_Instance_Body return Boolean is
5237       S : Entity_Id;
5238
5239    begin
5240       S := Current_Scope;
5241       while Present (S)
5242         and then S /= Standard_Standard
5243       loop
5244          if (Ekind (S) = E_Function
5245               or else Ekind (S) = E_Procedure)
5246            and then Is_Generic_Instance (S)
5247          then
5248             return True;
5249
5250          elsif Ekind (S) = E_Package
5251            and then In_Package_Body (S)
5252            and then Is_Generic_Instance (S)
5253          then
5254             return True;
5255          end if;
5256
5257          S := Scope (S);
5258       end loop;
5259
5260       return False;
5261    end In_Instance_Body;
5262
5263    -----------------------------
5264    -- In_Instance_Not_Visible --
5265    -----------------------------
5266
5267    function In_Instance_Not_Visible return Boolean is
5268       S : Entity_Id;
5269
5270    begin
5271       S := Current_Scope;
5272       while Present (S)
5273         and then S /= Standard_Standard
5274       loop
5275          if (Ekind (S) = E_Function
5276               or else Ekind (S) = E_Procedure)
5277            and then Is_Generic_Instance (S)
5278          then
5279             return True;
5280
5281          elsif Ekind (S) = E_Package
5282            and then (In_Package_Body (S) or else In_Private_Part (S))
5283            and then Is_Generic_Instance (S)
5284          then
5285             return True;
5286          end if;
5287
5288          S := Scope (S);
5289       end loop;
5290
5291       return False;
5292    end In_Instance_Not_Visible;
5293
5294    ------------------------------
5295    -- In_Instance_Visible_Part --
5296    ------------------------------
5297
5298    function In_Instance_Visible_Part return Boolean is
5299       S : Entity_Id;
5300
5301    begin
5302       S := Current_Scope;
5303       while Present (S)
5304         and then S /= Standard_Standard
5305       loop
5306          if Ekind (S) = E_Package
5307            and then Is_Generic_Instance (S)
5308            and then not In_Package_Body (S)
5309            and then not In_Private_Part (S)
5310          then
5311             return True;
5312          end if;
5313
5314          S := Scope (S);
5315       end loop;
5316
5317       return False;
5318    end In_Instance_Visible_Part;
5319
5320    ---------------------
5321    -- In_Package_Body --
5322    ---------------------
5323
5324    function In_Package_Body return Boolean is
5325       S : Entity_Id;
5326
5327    begin
5328       S := Current_Scope;
5329       while Present (S)
5330         and then S /= Standard_Standard
5331       loop
5332          if Ekind (S) = E_Package
5333            and then In_Package_Body (S)
5334          then
5335             return True;
5336          else
5337             S := Scope (S);
5338          end if;
5339       end loop;
5340
5341       return False;
5342    end In_Package_Body;
5343
5344    --------------------------------
5345    -- In_Parameter_Specification --
5346    --------------------------------
5347
5348    function In_Parameter_Specification (N : Node_Id) return Boolean is
5349       PN : Node_Id;
5350
5351    begin
5352       PN := Parent (N);
5353       while Present (PN) loop
5354          if Nkind (PN) = N_Parameter_Specification then
5355             return True;
5356          end if;
5357
5358          PN := Parent (PN);
5359       end loop;
5360
5361       return False;
5362    end In_Parameter_Specification;
5363
5364    --------------------------------------
5365    -- In_Subprogram_Or_Concurrent_Unit --
5366    --------------------------------------
5367
5368    function In_Subprogram_Or_Concurrent_Unit return Boolean is
5369       E : Entity_Id;
5370       K : Entity_Kind;
5371
5372    begin
5373       --  Use scope chain to check successively outer scopes
5374
5375       E := Current_Scope;
5376       loop
5377          K := Ekind (E);
5378
5379          if K in Subprogram_Kind
5380            or else K in Concurrent_Kind
5381            or else K in Generic_Subprogram_Kind
5382          then
5383             return True;
5384
5385          elsif E = Standard_Standard then
5386             return False;
5387          end if;
5388
5389          E := Scope (E);
5390       end loop;
5391    end In_Subprogram_Or_Concurrent_Unit;
5392
5393    ---------------------
5394    -- In_Visible_Part --
5395    ---------------------
5396
5397    function In_Visible_Part (Scope_Id : Entity_Id) return Boolean is
5398    begin
5399       return
5400         Is_Package_Or_Generic_Package (Scope_Id)
5401           and then In_Open_Scopes (Scope_Id)
5402           and then not In_Package_Body (Scope_Id)
5403           and then not In_Private_Part (Scope_Id);
5404    end In_Visible_Part;
5405
5406    ---------------------------------
5407    -- Insert_Explicit_Dereference --
5408    ---------------------------------
5409
5410    procedure Insert_Explicit_Dereference (N : Node_Id) is
5411       New_Prefix : constant Node_Id := Relocate_Node (N);
5412       Ent        : Entity_Id := Empty;
5413       Pref       : Node_Id;
5414       I          : Interp_Index;
5415       It         : Interp;
5416       T          : Entity_Id;
5417
5418    begin
5419       Save_Interps (N, New_Prefix);
5420
5421       --  Check if the node relocation requires readjustment of some SCIL
5422       --  dispatching node.
5423
5424       if Generate_SCIL
5425         and then Nkind (N) = N_Function_Call
5426       then
5427          Adjust_SCIL_Node (N, New_Prefix);
5428       end if;
5429
5430       Rewrite (N, Make_Explicit_Dereference (Sloc (N), Prefix => New_Prefix));
5431
5432       Set_Etype (N, Designated_Type (Etype (New_Prefix)));
5433
5434       if Is_Overloaded (New_Prefix) then
5435
5436          --  The dereference is also overloaded, and its interpretations are
5437          --  the designated types of the interpretations of the original node.
5438
5439          Set_Etype (N, Any_Type);
5440
5441          Get_First_Interp (New_Prefix, I, It);
5442          while Present (It.Nam) loop
5443             T := It.Typ;
5444
5445             if Is_Access_Type (T) then
5446                Add_One_Interp (N, Designated_Type (T), Designated_Type (T));
5447             end if;
5448
5449             Get_Next_Interp (I, It);
5450          end loop;
5451
5452          End_Interp_List;
5453
5454       else
5455          --  Prefix is unambiguous: mark the original prefix (which might
5456          --  Come_From_Source) as a reference, since the new (relocated) one
5457          --  won't be taken into account.
5458
5459          if Is_Entity_Name (New_Prefix) then
5460             Ent := Entity (New_Prefix);
5461
5462          --  For a retrieval of a subcomponent of some composite object,
5463          --  retrieve the ultimate entity if there is one.
5464
5465          elsif Nkind (New_Prefix) = N_Selected_Component
5466            or else Nkind (New_Prefix) = N_Indexed_Component
5467          then
5468             Pref := Prefix (New_Prefix);
5469             while Present (Pref)
5470               and then
5471                 (Nkind (Pref) = N_Selected_Component
5472                   or else Nkind (Pref) = N_Indexed_Component)
5473             loop
5474                Pref := Prefix (Pref);
5475             end loop;
5476
5477             if Present (Pref) and then Is_Entity_Name (Pref) then
5478                Ent := Entity (Pref);
5479             end if;
5480          end if;
5481
5482          if Present (Ent) then
5483             Generate_Reference (Ent, New_Prefix);
5484          end if;
5485       end if;
5486    end Insert_Explicit_Dereference;
5487
5488    ------------------------------------------
5489    -- Inspect_Deferred_Constant_Completion --
5490    ------------------------------------------
5491
5492    procedure Inspect_Deferred_Constant_Completion (Decls : List_Id) is
5493       Decl   : Node_Id;
5494
5495    begin
5496       Decl := First (Decls);
5497       while Present (Decl) loop
5498
5499          --  Deferred constant signature
5500
5501          if Nkind (Decl) = N_Object_Declaration
5502            and then Constant_Present (Decl)
5503            and then No (Expression (Decl))
5504
5505             --  No need to check internally generated constants
5506
5507            and then Comes_From_Source (Decl)
5508
5509             --  The constant is not completed. A full object declaration
5510             --  or a pragma Import complete a deferred constant.
5511
5512            and then not Has_Completion (Defining_Identifier (Decl))
5513          then
5514             Error_Msg_N
5515               ("constant declaration requires initialization expression",
5516               Defining_Identifier (Decl));
5517          end if;
5518
5519          Decl := Next (Decl);
5520       end loop;
5521    end Inspect_Deferred_Constant_Completion;
5522
5523    -------------------
5524    -- Is_AAMP_Float --
5525    -------------------
5526
5527    function Is_AAMP_Float (E : Entity_Id) return Boolean is
5528       pragma Assert (Is_Type (E));
5529    begin
5530       return AAMP_On_Target
5531          and then Is_Floating_Point_Type (E)
5532          and then E = Base_Type (E);
5533    end Is_AAMP_Float;
5534
5535    -----------------------------
5536    -- Is_Actual_Out_Parameter --
5537    -----------------------------
5538
5539    function Is_Actual_Out_Parameter (N : Node_Id) return Boolean is
5540       Formal : Entity_Id;
5541       Call   : Node_Id;
5542    begin
5543       Find_Actual (N, Formal, Call);
5544       return Present (Formal)
5545         and then Ekind (Formal) = E_Out_Parameter;
5546    end Is_Actual_Out_Parameter;
5547
5548    -------------------------
5549    -- Is_Actual_Parameter --
5550    -------------------------
5551
5552    function Is_Actual_Parameter (N : Node_Id) return Boolean is
5553       PK : constant Node_Kind := Nkind (Parent (N));
5554
5555    begin
5556       case PK is
5557          when N_Parameter_Association =>
5558             return N = Explicit_Actual_Parameter (Parent (N));
5559
5560          when N_Function_Call | N_Procedure_Call_Statement =>
5561             return Is_List_Member (N)
5562               and then
5563                 List_Containing (N) = Parameter_Associations (Parent (N));
5564
5565          when others =>
5566             return False;
5567       end case;
5568    end Is_Actual_Parameter;
5569
5570    ---------------------
5571    -- Is_Aliased_View --
5572    ---------------------
5573
5574    function Is_Aliased_View (Obj : Node_Id) return Boolean is
5575       E : Entity_Id;
5576
5577    begin
5578       if Is_Entity_Name (Obj) then
5579
5580          E := Entity (Obj);
5581
5582          return
5583            (Is_Object (E)
5584              and then
5585                (Is_Aliased (E)
5586                   or else (Present (Renamed_Object (E))
5587                              and then Is_Aliased_View (Renamed_Object (E)))))
5588
5589            or else ((Is_Formal (E)
5590                       or else Ekind (E) = E_Generic_In_Out_Parameter
5591                       or else Ekind (E) = E_Generic_In_Parameter)
5592                     and then Is_Tagged_Type (Etype (E)))
5593
5594            or else (Is_Concurrent_Type (E)
5595                      and then In_Open_Scopes (E))
5596
5597             --  Current instance of type, either directly or as rewritten
5598             --  reference to the current object.
5599
5600            or else (Is_Entity_Name (Original_Node (Obj))
5601                      and then Present (Entity (Original_Node (Obj)))
5602                      and then Is_Type (Entity (Original_Node (Obj))))
5603
5604            or else (Is_Type (E) and then E = Current_Scope)
5605
5606            or else (Is_Incomplete_Or_Private_Type (E)
5607                      and then Full_View (E) = Current_Scope);
5608
5609       elsif Nkind (Obj) = N_Selected_Component then
5610          return Is_Aliased (Entity (Selector_Name (Obj)));
5611
5612       elsif Nkind (Obj) = N_Indexed_Component then
5613          return Has_Aliased_Components (Etype (Prefix (Obj)))
5614            or else
5615              (Is_Access_Type (Etype (Prefix (Obj)))
5616                and then
5617               Has_Aliased_Components
5618                 (Designated_Type (Etype (Prefix (Obj)))));
5619
5620       elsif Nkind (Obj) = N_Unchecked_Type_Conversion
5621         or else Nkind (Obj) = N_Type_Conversion
5622       then
5623          return Is_Tagged_Type (Etype (Obj))
5624            and then Is_Aliased_View (Expression (Obj));
5625
5626       elsif Nkind (Obj) = N_Explicit_Dereference then
5627          return Nkind (Original_Node (Obj)) /= N_Function_Call;
5628
5629       else
5630          return False;
5631       end if;
5632    end Is_Aliased_View;
5633
5634    -------------------------
5635    -- Is_Ancestor_Package --
5636    -------------------------
5637
5638    function Is_Ancestor_Package
5639      (E1 : Entity_Id;
5640       E2 : Entity_Id) return Boolean
5641    is
5642       Par : Entity_Id;
5643
5644    begin
5645       Par := E2;
5646       while Present (Par)
5647         and then Par /= Standard_Standard
5648       loop
5649          if Par = E1 then
5650             return True;
5651          end if;
5652
5653          Par := Scope (Par);
5654       end loop;
5655
5656       return False;
5657    end Is_Ancestor_Package;
5658
5659    ----------------------
5660    -- Is_Atomic_Object --
5661    ----------------------
5662
5663    function Is_Atomic_Object (N : Node_Id) return Boolean is
5664
5665       function Object_Has_Atomic_Components (N : Node_Id) return Boolean;
5666       --  Determines if given object has atomic components
5667
5668       function Is_Atomic_Prefix (N : Node_Id) return Boolean;
5669       --  If prefix is an implicit dereference, examine designated type
5670
5671       ----------------------
5672       -- Is_Atomic_Prefix --
5673       ----------------------
5674
5675       function Is_Atomic_Prefix (N : Node_Id) return Boolean is
5676       begin
5677          if Is_Access_Type (Etype (N)) then
5678             return
5679               Has_Atomic_Components (Designated_Type (Etype (N)));
5680          else
5681             return Object_Has_Atomic_Components (N);
5682          end if;
5683       end Is_Atomic_Prefix;
5684
5685       ----------------------------------
5686       -- Object_Has_Atomic_Components --
5687       ----------------------------------
5688
5689       function Object_Has_Atomic_Components (N : Node_Id) return Boolean is
5690       begin
5691          if Has_Atomic_Components (Etype (N))
5692            or else Is_Atomic (Etype (N))
5693          then
5694             return True;
5695
5696          elsif Is_Entity_Name (N)
5697            and then (Has_Atomic_Components (Entity (N))
5698                       or else Is_Atomic (Entity (N)))
5699          then
5700             return True;
5701
5702          elsif Nkind (N) = N_Indexed_Component
5703            or else Nkind (N) = N_Selected_Component
5704          then
5705             return Is_Atomic_Prefix (Prefix (N));
5706
5707          else
5708             return False;
5709          end if;
5710       end Object_Has_Atomic_Components;
5711
5712    --  Start of processing for Is_Atomic_Object
5713
5714    begin
5715       if Is_Atomic (Etype (N))
5716         or else (Is_Entity_Name (N) and then Is_Atomic (Entity (N)))
5717       then
5718          return True;
5719
5720       elsif Nkind (N) = N_Indexed_Component
5721         or else Nkind (N) = N_Selected_Component
5722       then
5723          return Is_Atomic_Prefix (Prefix (N));
5724
5725       else
5726          return False;
5727       end if;
5728    end Is_Atomic_Object;
5729
5730    -------------------------
5731    -- Is_Coextension_Root --
5732    -------------------------
5733
5734    function Is_Coextension_Root (N : Node_Id) return Boolean is
5735    begin
5736       return
5737         Nkind (N) = N_Allocator
5738           and then Present (Coextensions (N))
5739
5740          --  Anonymous access discriminants carry a list of all nested
5741          --  controlled coextensions.
5742
5743           and then not Is_Dynamic_Coextension (N)
5744           and then not Is_Static_Coextension (N);
5745    end Is_Coextension_Root;
5746
5747    -----------------------------
5748    -- Is_Concurrent_Interface --
5749    -----------------------------
5750
5751    function Is_Concurrent_Interface (T : Entity_Id) return Boolean is
5752    begin
5753       return
5754         Is_Interface (T)
5755           and then
5756             (Is_Protected_Interface (T)
5757                or else Is_Synchronized_Interface (T)
5758                or else Is_Task_Interface (T));
5759    end Is_Concurrent_Interface;
5760
5761    --------------------------------------
5762    -- Is_Controlling_Limited_Procedure --
5763    --------------------------------------
5764
5765    function Is_Controlling_Limited_Procedure
5766      (Proc_Nam : Entity_Id) return Boolean
5767    is
5768       Param_Typ : Entity_Id := Empty;
5769
5770    begin
5771       if Ekind (Proc_Nam) = E_Procedure
5772         and then Present (Parameter_Specifications (Parent (Proc_Nam)))
5773       then
5774          Param_Typ := Etype (Parameter_Type (First (
5775                         Parameter_Specifications (Parent (Proc_Nam)))));
5776
5777       --  In this case where an Itype was created, the procedure call has been
5778       --  rewritten.
5779
5780       elsif Present (Associated_Node_For_Itype (Proc_Nam))
5781         and then Present (Original_Node (Associated_Node_For_Itype (Proc_Nam)))
5782         and then
5783           Present (Parameter_Associations
5784                      (Associated_Node_For_Itype (Proc_Nam)))
5785       then
5786          Param_Typ :=
5787            Etype (First (Parameter_Associations
5788                           (Associated_Node_For_Itype (Proc_Nam))));
5789       end if;
5790
5791       if Present (Param_Typ) then
5792          return
5793            Is_Interface (Param_Typ)
5794              and then Is_Limited_Record (Param_Typ);
5795       end if;
5796
5797       return False;
5798    end Is_Controlling_Limited_Procedure;
5799
5800    -----------------------------
5801    -- Is_CPP_Constructor_Call --
5802    -----------------------------
5803
5804    function Is_CPP_Constructor_Call (N : Node_Id) return Boolean is
5805    begin
5806       return Nkind (N) = N_Function_Call
5807         and then Is_CPP_Class (Etype (Etype (N)))
5808         and then Is_Constructor (Entity (Name (N)))
5809         and then Is_Imported (Entity (Name (N)));
5810    end Is_CPP_Constructor_Call;
5811
5812    ----------------------------------------------
5813    -- Is_Dependent_Component_Of_Mutable_Object --
5814    ----------------------------------------------
5815
5816    function Is_Dependent_Component_Of_Mutable_Object
5817      (Object : Node_Id) return   Boolean
5818    is
5819       P           : Node_Id;
5820       Prefix_Type : Entity_Id;
5821       P_Aliased   : Boolean := False;
5822       Comp        : Entity_Id;
5823
5824       function Is_Declared_Within_Variant (Comp : Entity_Id) return Boolean;
5825       --  Returns True if and only if Comp is declared within a variant part
5826
5827       --------------------------------
5828       -- Is_Declared_Within_Variant --
5829       --------------------------------
5830
5831       function Is_Declared_Within_Variant (Comp : Entity_Id) return Boolean is
5832          Comp_Decl : constant Node_Id   := Parent (Comp);
5833          Comp_List : constant Node_Id   := Parent (Comp_Decl);
5834       begin
5835          return Nkind (Parent (Comp_List)) = N_Variant;
5836       end Is_Declared_Within_Variant;
5837
5838    --  Start of processing for Is_Dependent_Component_Of_Mutable_Object
5839
5840    begin
5841       if Is_Variable (Object) then
5842
5843          if Nkind (Object) = N_Selected_Component then
5844             P := Prefix (Object);
5845             Prefix_Type := Etype (P);
5846
5847             if Is_Entity_Name (P) then
5848
5849                if Ekind (Entity (P)) = E_Generic_In_Out_Parameter then
5850                   Prefix_Type := Base_Type (Prefix_Type);
5851                end if;
5852
5853                if Is_Aliased (Entity (P)) then
5854                   P_Aliased := True;
5855                end if;
5856
5857             --  A discriminant check on a selected component may be
5858             --  expanded into a dereference when removing side-effects.
5859             --  Recover the original node and its type, which may be
5860             --  unconstrained.
5861
5862             elsif Nkind (P) = N_Explicit_Dereference
5863               and then not (Comes_From_Source (P))
5864             then
5865                P := Original_Node (P);
5866                Prefix_Type := Etype (P);
5867
5868             else
5869                --  Check for prefix being an aliased component ???
5870                null;
5871
5872             end if;
5873
5874             --  A heap object is constrained by its initial value
5875
5876             --  Ada 2005 (AI-363): Always assume the object could be mutable in
5877             --  the dereferenced case, since the access value might denote an
5878             --  unconstrained aliased object, whereas in Ada 95 the designated
5879             --  object is guaranteed to be constrained. A worst-case assumption
5880             --  has to apply in Ada 2005 because we can't tell at compile time
5881             --  whether the object is "constrained by its initial value"
5882             --  (despite the fact that 3.10.2(26/2) and 8.5.1(5/2) are
5883             --  semantic rules -- these rules are acknowledged to need fixing).
5884
5885             if Ada_Version < Ada_05 then
5886                if Is_Access_Type (Prefix_Type)
5887                  or else Nkind (P) = N_Explicit_Dereference
5888                then
5889                   return False;
5890                end if;
5891
5892             elsif Ada_Version >= Ada_05 then
5893                if Is_Access_Type (Prefix_Type) then
5894
5895                   --  If the access type is pool-specific, and there is no
5896                   --  constrained partial view of the designated type, then the
5897                   --  designated object is known to be constrained.
5898
5899                   if Ekind (Prefix_Type) = E_Access_Type
5900                     and then not Has_Constrained_Partial_View
5901                                    (Designated_Type (Prefix_Type))
5902                   then
5903                      return False;
5904
5905                   --  Otherwise (general access type, or there is a constrained
5906                   --  partial view of the designated type), we need to check
5907                   --  based on the designated type.
5908
5909                   else
5910                      Prefix_Type := Designated_Type (Prefix_Type);
5911                   end if;
5912                end if;
5913             end if;
5914
5915             Comp :=
5916               Original_Record_Component (Entity (Selector_Name (Object)));
5917
5918             --  As per AI-0017, the renaming is illegal in a generic body,
5919             --  even if the subtype is indefinite.
5920
5921             --  Ada 2005 (AI-363): In Ada 2005 an aliased object can be mutable
5922
5923             if not Is_Constrained (Prefix_Type)
5924               and then (not Is_Indefinite_Subtype (Prefix_Type)
5925                          or else
5926                           (Is_Generic_Type (Prefix_Type)
5927                             and then Ekind (Current_Scope) = E_Generic_Package
5928                             and then In_Package_Body (Current_Scope)))
5929
5930               and then (Is_Declared_Within_Variant (Comp)
5931                           or else Has_Discriminant_Dependent_Constraint (Comp))
5932               and then (not P_Aliased or else Ada_Version >= Ada_05)
5933             then
5934                return True;
5935
5936             else
5937                return
5938                  Is_Dependent_Component_Of_Mutable_Object (Prefix (Object));
5939
5940             end if;
5941
5942          elsif Nkind (Object) = N_Indexed_Component
5943            or else Nkind (Object) = N_Slice
5944          then
5945             return Is_Dependent_Component_Of_Mutable_Object (Prefix (Object));
5946
5947          --  A type conversion that Is_Variable is a view conversion:
5948          --  go back to the denoted object.
5949
5950          elsif Nkind (Object) = N_Type_Conversion then
5951             return
5952               Is_Dependent_Component_Of_Mutable_Object (Expression (Object));
5953          end if;
5954       end if;
5955
5956       return False;
5957    end Is_Dependent_Component_Of_Mutable_Object;
5958
5959    ---------------------
5960    -- Is_Dereferenced --
5961    ---------------------
5962
5963    function Is_Dereferenced (N : Node_Id) return Boolean is
5964       P : constant Node_Id := Parent (N);
5965    begin
5966       return
5967          (Nkind (P) = N_Selected_Component
5968             or else
5969           Nkind (P) = N_Explicit_Dereference
5970             or else
5971           Nkind (P) = N_Indexed_Component
5972             or else
5973           Nkind (P) = N_Slice)
5974         and then Prefix (P) = N;
5975    end Is_Dereferenced;
5976
5977    ----------------------
5978    -- Is_Descendent_Of --
5979    ----------------------
5980
5981    function Is_Descendent_Of (T1 : Entity_Id; T2 : Entity_Id) return Boolean is
5982       T    : Entity_Id;
5983       Etyp : Entity_Id;
5984
5985    begin
5986       pragma Assert (Nkind (T1) in N_Entity);
5987       pragma Assert (Nkind (T2) in N_Entity);
5988
5989       T := Base_Type (T1);
5990
5991       --  Immediate return if the types match
5992
5993       if T = T2 then
5994          return True;
5995
5996       --  Comment needed here ???
5997
5998       elsif Ekind (T) = E_Class_Wide_Type then
5999          return Etype (T) = T2;
6000
6001       --  All other cases
6002
6003       else
6004          loop
6005             Etyp := Etype (T);
6006
6007             --  Done if we found the type we are looking for
6008
6009             if Etyp = T2 then
6010                return True;
6011
6012             --  Done if no more derivations to check
6013
6014             elsif T = T1
6015               or else T = Etyp
6016             then
6017                return False;
6018
6019             --  Following test catches error cases resulting from prev errors
6020
6021             elsif No (Etyp) then
6022                return False;
6023
6024             elsif Is_Private_Type (T) and then Etyp = Full_View (T) then
6025                return False;
6026
6027             elsif Is_Private_Type (Etyp) and then Full_View (Etyp) = T then
6028                return False;
6029             end if;
6030
6031             T := Base_Type (Etyp);
6032          end loop;
6033       end if;
6034    end Is_Descendent_Of;
6035
6036    --------------
6037    -- Is_False --
6038    --------------
6039
6040    function Is_False (U : Uint) return Boolean is
6041    begin
6042       return (U = 0);
6043    end Is_False;
6044
6045    ---------------------------
6046    -- Is_Fixed_Model_Number --
6047    ---------------------------
6048
6049    function Is_Fixed_Model_Number (U : Ureal; T : Entity_Id) return Boolean is
6050       S : constant Ureal := Small_Value (T);
6051       M : Urealp.Save_Mark;
6052       R : Boolean;
6053    begin
6054       M := Urealp.Mark;
6055       R := (U = UR_Trunc (U / S) * S);
6056       Urealp.Release (M);
6057       return R;
6058    end Is_Fixed_Model_Number;
6059
6060    -------------------------------
6061    -- Is_Fully_Initialized_Type --
6062    -------------------------------
6063
6064    function Is_Fully_Initialized_Type (Typ : Entity_Id) return Boolean is
6065    begin
6066       if Is_Scalar_Type (Typ) then
6067          return False;
6068
6069       elsif Is_Access_Type (Typ) then
6070          return True;
6071
6072       elsif Is_Array_Type (Typ) then
6073          if Is_Fully_Initialized_Type (Component_Type (Typ)) then
6074             return True;
6075          end if;
6076
6077          --  An interesting case, if we have a constrained type one of whose
6078          --  bounds is known to be null, then there are no elements to be
6079          --  initialized, so all the elements are initialized!
6080
6081          if Is_Constrained (Typ) then
6082             declare
6083                Indx     : Node_Id;
6084                Indx_Typ : Entity_Id;
6085                Lbd, Hbd : Node_Id;
6086
6087             begin
6088                Indx := First_Index (Typ);
6089                while Present (Indx) loop
6090                   if Etype (Indx) = Any_Type then
6091                      return False;
6092
6093                   --  If index is a range, use directly
6094
6095                   elsif Nkind (Indx) = N_Range then
6096                      Lbd := Low_Bound  (Indx);
6097                      Hbd := High_Bound (Indx);
6098
6099                   else
6100                      Indx_Typ := Etype (Indx);
6101
6102                      if Is_Private_Type (Indx_Typ)  then
6103                         Indx_Typ := Full_View (Indx_Typ);
6104                      end if;
6105
6106                      if No (Indx_Typ) or else Etype (Indx_Typ) = Any_Type then
6107                         return False;
6108                      else
6109                         Lbd := Type_Low_Bound  (Indx_Typ);
6110                         Hbd := Type_High_Bound (Indx_Typ);
6111                      end if;
6112                   end if;
6113
6114                   if Compile_Time_Known_Value (Lbd)
6115                     and then Compile_Time_Known_Value (Hbd)
6116                   then
6117                      if Expr_Value (Hbd) < Expr_Value (Lbd) then
6118                         return True;
6119                      end if;
6120                   end if;
6121
6122                   Next_Index (Indx);
6123                end loop;
6124             end;
6125          end if;
6126
6127          --  If no null indexes, then type is not fully initialized
6128
6129          return False;
6130
6131       --  Record types
6132
6133       elsif Is_Record_Type (Typ) then
6134          if Has_Discriminants (Typ)
6135            and then
6136              Present (Discriminant_Default_Value (First_Discriminant (Typ)))
6137            and then Is_Fully_Initialized_Variant (Typ)
6138          then
6139             return True;
6140          end if;
6141
6142          --  Controlled records are considered to be fully initialized if
6143          --  there is a user defined Initialize routine. This may not be
6144          --  entirely correct, but as the spec notes, we are guessing here
6145          --  what is best from the point of view of issuing warnings.
6146
6147          if Is_Controlled (Typ) then
6148             declare
6149                Utyp : constant Entity_Id := Underlying_Type (Typ);
6150
6151             begin
6152                if Present (Utyp) then
6153                   declare
6154                      Init : constant Entity_Id :=
6155                               (Find_Prim_Op
6156                                  (Underlying_Type (Typ), Name_Initialize));
6157
6158                   begin
6159                      if Present (Init)
6160                        and then Comes_From_Source (Init)
6161                        and then not
6162                          Is_Predefined_File_Name
6163                            (File_Name (Get_Source_File_Index (Sloc (Init))))
6164                      then
6165                         return True;
6166
6167                      elsif Has_Null_Extension (Typ)
6168                         and then
6169                           Is_Fully_Initialized_Type
6170                             (Etype (Base_Type (Typ)))
6171                      then
6172                         return True;
6173                      end if;
6174                   end;
6175                end if;
6176             end;
6177          end if;
6178
6179          --  Otherwise see if all record components are initialized
6180
6181          declare
6182             Ent : Entity_Id;
6183
6184          begin
6185             Ent := First_Entity (Typ);
6186             while Present (Ent) loop
6187                if Chars (Ent) = Name_uController then
6188                   null;
6189
6190                elsif Ekind (Ent) = E_Component
6191                  and then (No (Parent (Ent))
6192                              or else No (Expression (Parent (Ent))))
6193                  and then not Is_Fully_Initialized_Type (Etype (Ent))
6194
6195                   --  Special VM case for tag components, which need to be
6196                   --  defined in this case, but are never initialized as VMs
6197                   --  are using other dispatching mechanisms. Ignore this
6198                   --  uninitialized case. Note that this applies both to the
6199                   --  uTag entry and the main vtable pointer (CPP_Class case).
6200
6201                  and then (Tagged_Type_Expansion or else not Is_Tag (Ent))
6202                then
6203                   return False;
6204                end if;
6205
6206                Next_Entity (Ent);
6207             end loop;
6208          end;
6209
6210          --  No uninitialized components, so type is fully initialized.
6211          --  Note that this catches the case of no components as well.
6212
6213          return True;
6214
6215       elsif Is_Concurrent_Type (Typ) then
6216          return True;
6217
6218       elsif Is_Private_Type (Typ) then
6219          declare
6220             U : constant Entity_Id := Underlying_Type (Typ);
6221
6222          begin
6223             if No (U) then
6224                return False;
6225             else
6226                return Is_Fully_Initialized_Type (U);
6227             end if;
6228          end;
6229
6230       else
6231          return False;
6232       end if;
6233    end Is_Fully_Initialized_Type;
6234
6235    ----------------------------------
6236    -- Is_Fully_Initialized_Variant --
6237    ----------------------------------
6238
6239    function Is_Fully_Initialized_Variant (Typ : Entity_Id) return Boolean is
6240       Loc           : constant Source_Ptr := Sloc (Typ);
6241       Constraints   : constant List_Id    := New_List;
6242       Components    : constant Elist_Id   := New_Elmt_List;
6243       Comp_Elmt     : Elmt_Id;
6244       Comp_Id       : Node_Id;
6245       Comp_List     : Node_Id;
6246       Discr         : Entity_Id;
6247       Discr_Val     : Node_Id;
6248
6249       Report_Errors : Boolean;
6250       pragma Warnings (Off, Report_Errors);
6251
6252    begin
6253       if Serious_Errors_Detected > 0 then
6254          return False;
6255       end if;
6256
6257       if Is_Record_Type (Typ)
6258         and then Nkind (Parent (Typ)) = N_Full_Type_Declaration
6259         and then Nkind (Type_Definition (Parent (Typ))) = N_Record_Definition
6260       then
6261          Comp_List := Component_List (Type_Definition (Parent (Typ)));
6262
6263          Discr := First_Discriminant (Typ);
6264          while Present (Discr) loop
6265             if Nkind (Parent (Discr)) = N_Discriminant_Specification then
6266                Discr_Val := Expression (Parent (Discr));
6267
6268                if Present (Discr_Val)
6269                  and then Is_OK_Static_Expression (Discr_Val)
6270                then
6271                   Append_To (Constraints,
6272                     Make_Component_Association (Loc,
6273                       Choices    => New_List (New_Occurrence_Of (Discr, Loc)),
6274                       Expression => New_Copy (Discr_Val)));
6275                else
6276                   return False;
6277                end if;
6278             else
6279                return False;
6280             end if;
6281
6282             Next_Discriminant (Discr);
6283          end loop;
6284
6285          Gather_Components
6286            (Typ           => Typ,
6287             Comp_List     => Comp_List,
6288             Governed_By   => Constraints,
6289             Into          => Components,
6290             Report_Errors => Report_Errors);
6291
6292          --  Check that each component present is fully initialized
6293
6294          Comp_Elmt := First_Elmt (Components);
6295          while Present (Comp_Elmt) loop
6296             Comp_Id := Node (Comp_Elmt);
6297
6298             if Ekind (Comp_Id) = E_Component
6299               and then (No (Parent (Comp_Id))
6300                          or else No (Expression (Parent (Comp_Id))))
6301               and then not Is_Fully_Initialized_Type (Etype (Comp_Id))
6302             then
6303                return False;
6304             end if;
6305
6306             Next_Elmt (Comp_Elmt);
6307          end loop;
6308
6309          return True;
6310
6311       elsif Is_Private_Type (Typ) then
6312          declare
6313             U : constant Entity_Id := Underlying_Type (Typ);
6314
6315          begin
6316             if No (U) then
6317                return False;
6318             else
6319                return Is_Fully_Initialized_Variant (U);
6320             end if;
6321          end;
6322       else
6323          return False;
6324       end if;
6325    end Is_Fully_Initialized_Variant;
6326
6327    ------------
6328    -- Is_LHS --
6329    ------------
6330
6331    --  We seem to have a lot of overlapping functions that do similar things
6332    --  (testing for left hand sides or lvalues???). Anyway, since this one is
6333    --  purely syntactic, it should be in Sem_Aux I would think???
6334
6335    function Is_LHS (N : Node_Id) return Boolean is
6336       P : constant Node_Id := Parent (N);
6337    begin
6338       return Nkind (P) = N_Assignment_Statement
6339         and then Name (P) = N;
6340    end Is_LHS;
6341
6342    ----------------------------
6343    -- Is_Inherited_Operation --
6344    ----------------------------
6345
6346    function Is_Inherited_Operation (E : Entity_Id) return Boolean is
6347       Kind : constant Node_Kind := Nkind (Parent (E));
6348    begin
6349       pragma Assert (Is_Overloadable (E));
6350       return Kind = N_Full_Type_Declaration
6351         or else Kind = N_Private_Extension_Declaration
6352         or else Kind = N_Subtype_Declaration
6353         or else (Ekind (E) = E_Enumeration_Literal
6354                   and then Is_Derived_Type (Etype (E)));
6355    end Is_Inherited_Operation;
6356
6357    -----------------------------
6358    -- Is_Library_Level_Entity --
6359    -----------------------------
6360
6361    function Is_Library_Level_Entity (E : Entity_Id) return Boolean is
6362    begin
6363       --  The following is a small optimization, and it also properly handles
6364       --  discriminals, which in task bodies might appear in expressions before
6365       --  the corresponding procedure has been created, and which therefore do
6366       --  not have an assigned scope.
6367
6368       if Ekind (E) in Formal_Kind then
6369          return False;
6370       end if;
6371
6372       --  Normal test is simply that the enclosing dynamic scope is Standard
6373
6374       return Enclosing_Dynamic_Scope (E) = Standard_Standard;
6375    end Is_Library_Level_Entity;
6376
6377    ---------------------------------
6378    -- Is_Local_Variable_Reference --
6379    ---------------------------------
6380
6381    function Is_Local_Variable_Reference (Expr : Node_Id) return Boolean is
6382    begin
6383       if not Is_Entity_Name (Expr) then
6384          return False;
6385
6386       else
6387          declare
6388             Ent : constant Entity_Id := Entity (Expr);
6389             Sub : constant Entity_Id := Enclosing_Subprogram (Ent);
6390          begin
6391             if not Ekind_In (Ent, E_Variable, E_In_Out_Parameter) then
6392                return False;
6393             else
6394                return Present (Sub) and then Sub = Current_Subprogram;
6395             end if;
6396          end;
6397       end if;
6398    end Is_Local_Variable_Reference;
6399
6400    -------------------------
6401    -- Is_Object_Reference --
6402    -------------------------
6403
6404    function Is_Object_Reference (N : Node_Id) return Boolean is
6405    begin
6406       if Is_Entity_Name (N) then
6407          return Present (Entity (N)) and then Is_Object (Entity (N));
6408
6409       else
6410          case Nkind (N) is
6411             when N_Indexed_Component | N_Slice =>
6412                return
6413                  Is_Object_Reference (Prefix (N))
6414                    or else Is_Access_Type (Etype (Prefix (N)));
6415
6416             --  In Ada95, a function call is a constant object; a procedure
6417             --  call is not.
6418
6419             when N_Function_Call =>
6420                return Etype (N) /= Standard_Void_Type;
6421
6422             --  A reference to the stream attribute Input is a function call
6423
6424             when N_Attribute_Reference =>
6425                return Attribute_Name (N) = Name_Input;
6426
6427             when N_Selected_Component =>
6428                return
6429                  Is_Object_Reference (Selector_Name (N))
6430                    and then
6431                      (Is_Object_Reference (Prefix (N))
6432                         or else Is_Access_Type (Etype (Prefix (N))));
6433
6434             when N_Explicit_Dereference =>
6435                return True;
6436
6437             --  A view conversion of a tagged object is an object reference
6438
6439             when N_Type_Conversion =>
6440                return Is_Tagged_Type (Etype (Subtype_Mark (N)))
6441                  and then Is_Tagged_Type (Etype (Expression (N)))
6442                  and then Is_Object_Reference (Expression (N));
6443
6444             --  An unchecked type conversion is considered to be an object if
6445             --  the operand is an object (this construction arises only as a
6446             --  result of expansion activities).
6447
6448             when N_Unchecked_Type_Conversion =>
6449                return True;
6450
6451             when others =>
6452                return False;
6453          end case;
6454       end if;
6455    end Is_Object_Reference;
6456
6457    -----------------------------------
6458    -- Is_OK_Variable_For_Out_Formal --
6459    -----------------------------------
6460
6461    function Is_OK_Variable_For_Out_Formal (AV : Node_Id) return Boolean is
6462    begin
6463       Note_Possible_Modification (AV, Sure => True);
6464
6465       --  We must reject parenthesized variable names. The check for
6466       --  Comes_From_Source is present because there are currently
6467       --  cases where the compiler violates this rule (e.g. passing
6468       --  a task object to its controlled Initialize routine).
6469
6470       if Paren_Count (AV) > 0 and then Comes_From_Source (AV) then
6471          return False;
6472
6473       --  A variable is always allowed
6474
6475       elsif Is_Variable (AV) then
6476          return True;
6477
6478       --  Unchecked conversions are allowed only if they come from the
6479       --  generated code, which sometimes uses unchecked conversions for out
6480       --  parameters in cases where code generation is unaffected. We tell
6481       --  source unchecked conversions by seeing if they are rewrites of an
6482       --  original Unchecked_Conversion function call, or of an explicit
6483       --  conversion of a function call.
6484
6485       elsif Nkind (AV) = N_Unchecked_Type_Conversion then
6486          if Nkind (Original_Node (AV)) = N_Function_Call then
6487             return False;
6488
6489          elsif Comes_From_Source (AV)
6490            and then Nkind (Original_Node (Expression (AV))) = N_Function_Call
6491          then
6492             return False;
6493
6494          elsif Nkind (Original_Node (AV)) = N_Type_Conversion then
6495             return Is_OK_Variable_For_Out_Formal (Expression (AV));
6496
6497          else
6498             return True;
6499          end if;
6500
6501       --  Normal type conversions are allowed if argument is a variable
6502
6503       elsif Nkind (AV) = N_Type_Conversion then
6504          if Is_Variable (Expression (AV))
6505            and then Paren_Count (Expression (AV)) = 0
6506          then
6507             Note_Possible_Modification (Expression (AV), Sure => True);
6508             return True;
6509
6510          --  We also allow a non-parenthesized expression that raises
6511          --  constraint error if it rewrites what used to be a variable
6512
6513          elsif Raises_Constraint_Error (Expression (AV))
6514             and then Paren_Count (Expression (AV)) = 0
6515             and then Is_Variable (Original_Node (Expression (AV)))
6516          then
6517             return True;
6518
6519          --  Type conversion of something other than a variable
6520
6521          else
6522             return False;
6523          end if;
6524
6525       --  If this node is rewritten, then test the original form, if that is
6526       --  OK, then we consider the rewritten node OK (for example, if the
6527       --  original node is a conversion, then Is_Variable will not be true
6528       --  but we still want to allow the conversion if it converts a variable).
6529
6530       elsif Original_Node (AV) /= AV then
6531          return Is_OK_Variable_For_Out_Formal (Original_Node (AV));
6532
6533       --  All other non-variables are rejected
6534
6535       else
6536          return False;
6537       end if;
6538    end Is_OK_Variable_For_Out_Formal;
6539
6540    -----------------------------------
6541    -- Is_Partially_Initialized_Type --
6542    -----------------------------------
6543
6544    function Is_Partially_Initialized_Type (Typ : Entity_Id) return Boolean is
6545    begin
6546       if Is_Scalar_Type (Typ) then
6547          return False;
6548
6549       elsif Is_Access_Type (Typ) then
6550          return True;
6551
6552       elsif Is_Array_Type (Typ) then
6553
6554          --  If component type is partially initialized, so is array type
6555
6556          if Is_Partially_Initialized_Type (Component_Type (Typ)) then
6557             return True;
6558
6559          --  Otherwise we are only partially initialized if we are fully
6560          --  initialized (this is the empty array case, no point in us
6561          --  duplicating that code here).
6562
6563          else
6564             return Is_Fully_Initialized_Type (Typ);
6565          end if;
6566
6567       elsif Is_Record_Type (Typ) then
6568
6569          --  A discriminated type is always partially initialized
6570
6571          if Has_Discriminants (Typ) then
6572             return True;
6573
6574          --  A tagged type is always partially initialized
6575
6576          elsif Is_Tagged_Type (Typ) then
6577             return True;
6578
6579          --  Case of non-discriminated record
6580
6581          else
6582             declare
6583                Ent : Entity_Id;
6584
6585                Component_Present : Boolean := False;
6586                --  Set True if at least one component is present. If no
6587                --  components are present, then record type is fully
6588                --  initialized (another odd case, like the null array).
6589
6590             begin
6591                --  Loop through components
6592
6593                Ent := First_Entity (Typ);
6594                while Present (Ent) loop
6595                   if Ekind (Ent) = E_Component then
6596                      Component_Present := True;
6597
6598                      --  If a component has an initialization expression then
6599                      --  the enclosing record type is partially initialized
6600
6601                      if Present (Parent (Ent))
6602                        and then Present (Expression (Parent (Ent)))
6603                      then
6604                         return True;
6605
6606                      --  If a component is of a type which is itself partially
6607                      --  initialized, then the enclosing record type is also.
6608
6609                      elsif Is_Partially_Initialized_Type (Etype (Ent)) then
6610                         return True;
6611                      end if;
6612                   end if;
6613
6614                   Next_Entity (Ent);
6615                end loop;
6616
6617                --  No initialized components found. If we found any components
6618                --  they were all uninitialized so the result is false.
6619
6620                if Component_Present then
6621                   return False;
6622
6623                --  But if we found no components, then all the components are
6624                --  initialized so we consider the type to be initialized.
6625
6626                else
6627                   return True;
6628                end if;
6629             end;
6630          end if;
6631
6632       --  Concurrent types are always fully initialized
6633
6634       elsif Is_Concurrent_Type (Typ) then
6635          return True;
6636
6637       --  For a private type, go to underlying type. If there is no underlying
6638       --  type then just assume this partially initialized. Not clear if this
6639       --  can happen in a non-error case, but no harm in testing for this.
6640
6641       elsif Is_Private_Type (Typ) then
6642          declare
6643             U : constant Entity_Id := Underlying_Type (Typ);
6644          begin
6645             if No (U) then
6646                return True;
6647             else
6648                return Is_Partially_Initialized_Type (U);
6649             end if;
6650          end;
6651
6652       --  For any other type (are there any?) assume partially initialized
6653
6654       else
6655          return True;
6656       end if;
6657    end Is_Partially_Initialized_Type;
6658
6659    ------------------------------------
6660    -- Is_Potentially_Persistent_Type --
6661    ------------------------------------
6662
6663    function Is_Potentially_Persistent_Type (T : Entity_Id) return Boolean is
6664       Comp : Entity_Id;
6665       Indx : Node_Id;
6666
6667    begin
6668       --  For private type, test corresponding full type
6669
6670       if Is_Private_Type (T) then
6671          return Is_Potentially_Persistent_Type (Full_View (T));
6672
6673       --  Scalar types are potentially persistent
6674
6675       elsif Is_Scalar_Type (T) then
6676          return True;
6677
6678       --  Record type is potentially persistent if not tagged and the types of
6679       --  all it components are potentially persistent, and no component has
6680       --  an initialization expression.
6681
6682       elsif Is_Record_Type (T)
6683         and then not Is_Tagged_Type (T)
6684         and then not Is_Partially_Initialized_Type (T)
6685       then
6686          Comp := First_Component (T);
6687          while Present (Comp) loop
6688             if not Is_Potentially_Persistent_Type (Etype (Comp)) then
6689                return False;
6690             else
6691                Next_Entity (Comp);
6692             end if;
6693          end loop;
6694
6695          return True;
6696
6697       --  Array type is potentially persistent if its component type is
6698       --  potentially persistent and if all its constraints are static.
6699
6700       elsif Is_Array_Type (T) then
6701          if not Is_Potentially_Persistent_Type (Component_Type (T)) then
6702             return False;
6703          end if;
6704
6705          Indx := First_Index (T);
6706          while Present (Indx) loop
6707             if not Is_OK_Static_Subtype (Etype (Indx)) then
6708                return False;
6709             else
6710                Next_Index (Indx);
6711             end if;
6712          end loop;
6713
6714          return True;
6715
6716       --  All other types are not potentially persistent
6717
6718       else
6719          return False;
6720       end if;
6721    end Is_Potentially_Persistent_Type;
6722
6723    ---------------------------------
6724    -- Is_Protected_Self_Reference --
6725    ---------------------------------
6726
6727    function Is_Protected_Self_Reference (N : Node_Id) return Boolean is
6728
6729       function In_Access_Definition (N : Node_Id) return Boolean;
6730       --  Returns true if N belongs to an access definition
6731
6732       --------------------------
6733       -- In_Access_Definition --
6734       --------------------------
6735
6736       function In_Access_Definition (N : Node_Id) return Boolean is
6737          P : Node_Id;
6738
6739       begin
6740          P := Parent (N);
6741          while Present (P) loop
6742             if Nkind (P) = N_Access_Definition then
6743                return True;
6744             end if;
6745
6746             P := Parent (P);
6747          end loop;
6748
6749          return False;
6750       end In_Access_Definition;
6751
6752    --  Start of processing for Is_Protected_Self_Reference
6753
6754    begin
6755       --  Verify that prefix is analyzed and has the proper form. Note that
6756       --  the attributes Elab_Spec, Elab_Body, and UET_Address, which also
6757       --  produce the address of an entity, do not analyze their prefix
6758       --  because they denote entities that are not necessarily visible.
6759       --  Neither of them can apply to a protected type.
6760
6761       return Ada_Version >= Ada_05
6762         and then Is_Entity_Name (N)
6763         and then Present (Entity (N))
6764         and then Is_Protected_Type (Entity (N))
6765         and then In_Open_Scopes (Entity (N))
6766         and then not In_Access_Definition (N);
6767    end Is_Protected_Self_Reference;
6768
6769    -----------------------------
6770    -- Is_RCI_Pkg_Spec_Or_Body --
6771    -----------------------------
6772
6773    function Is_RCI_Pkg_Spec_Or_Body (Cunit : Node_Id) return Boolean is
6774
6775       function Is_RCI_Pkg_Decl_Cunit (Cunit : Node_Id) return Boolean;
6776       --  Return True if the unit of Cunit is an RCI package declaration
6777
6778       ---------------------------
6779       -- Is_RCI_Pkg_Decl_Cunit --
6780       ---------------------------
6781
6782       function Is_RCI_Pkg_Decl_Cunit (Cunit : Node_Id) return Boolean is
6783          The_Unit : constant Node_Id := Unit (Cunit);
6784
6785       begin
6786          if Nkind (The_Unit) /= N_Package_Declaration then
6787             return False;
6788          end if;
6789
6790          return Is_Remote_Call_Interface (Defining_Entity (The_Unit));
6791       end Is_RCI_Pkg_Decl_Cunit;
6792
6793    --  Start of processing for Is_RCI_Pkg_Spec_Or_Body
6794
6795    begin
6796       return Is_RCI_Pkg_Decl_Cunit (Cunit)
6797         or else
6798          (Nkind (Unit (Cunit)) = N_Package_Body
6799            and then Is_RCI_Pkg_Decl_Cunit (Library_Unit (Cunit)));
6800    end Is_RCI_Pkg_Spec_Or_Body;
6801
6802    -----------------------------------------
6803    -- Is_Remote_Access_To_Class_Wide_Type --
6804    -----------------------------------------
6805
6806    function Is_Remote_Access_To_Class_Wide_Type
6807      (E : Entity_Id) return Boolean
6808    is
6809    begin
6810       --  A remote access to class-wide type is a general access to object type
6811       --  declared in the visible part of a Remote_Types or Remote_Call_
6812       --  Interface unit.
6813
6814       return Ekind (E) = E_General_Access_Type
6815         and then (Is_Remote_Call_Interface (E) or else Is_Remote_Types (E));
6816    end Is_Remote_Access_To_Class_Wide_Type;
6817
6818    -----------------------------------------
6819    -- Is_Remote_Access_To_Subprogram_Type --
6820    -----------------------------------------
6821
6822    function Is_Remote_Access_To_Subprogram_Type
6823      (E : Entity_Id) return Boolean
6824    is
6825    begin
6826       return (Ekind (E) = E_Access_Subprogram_Type
6827                 or else (Ekind (E) = E_Record_Type
6828                            and then Present (Corresponding_Remote_Type (E))))
6829         and then (Is_Remote_Call_Interface (E) or else Is_Remote_Types (E));
6830    end Is_Remote_Access_To_Subprogram_Type;
6831
6832    --------------------
6833    -- Is_Remote_Call --
6834    --------------------
6835
6836    function Is_Remote_Call (N : Node_Id) return Boolean is
6837    begin
6838       if Nkind (N) /= N_Procedure_Call_Statement
6839         and then Nkind (N) /= N_Function_Call
6840       then
6841          --  An entry call cannot be remote
6842
6843          return False;
6844
6845       elsif Nkind (Name (N)) in N_Has_Entity
6846         and then Is_Remote_Call_Interface (Entity (Name (N)))
6847       then
6848          --  A subprogram declared in the spec of a RCI package is remote
6849
6850          return True;
6851
6852       elsif Nkind (Name (N)) = N_Explicit_Dereference
6853         and then Is_Remote_Access_To_Subprogram_Type
6854                    (Etype (Prefix (Name (N))))
6855       then
6856          --  The dereference of a RAS is a remote call
6857
6858          return True;
6859
6860       elsif Present (Controlling_Argument (N))
6861         and then Is_Remote_Access_To_Class_Wide_Type
6862           (Etype (Controlling_Argument (N)))
6863       then
6864          --  Any primitive operation call with a controlling argument of
6865          --  a RACW type is a remote call.
6866
6867          return True;
6868       end if;
6869
6870       --  All other calls are local calls
6871
6872       return False;
6873    end Is_Remote_Call;
6874
6875    ----------------------
6876    -- Is_Renamed_Entry --
6877    ----------------------
6878
6879    function Is_Renamed_Entry (Proc_Nam : Entity_Id) return Boolean is
6880       Orig_Node : Node_Id := Empty;
6881       Subp_Decl : Node_Id := Parent (Parent (Proc_Nam));
6882
6883       function Is_Entry (Nam : Node_Id) return Boolean;
6884       --  Determine whether Nam is an entry. Traverse selectors if there are
6885       --  nested selected components.
6886
6887       --------------
6888       -- Is_Entry --
6889       --------------
6890
6891       function Is_Entry (Nam : Node_Id) return Boolean is
6892       begin
6893          if Nkind (Nam) = N_Selected_Component then
6894             return Is_Entry (Selector_Name (Nam));
6895          end if;
6896
6897          return Ekind (Entity (Nam)) = E_Entry;
6898       end Is_Entry;
6899
6900    --  Start of processing for Is_Renamed_Entry
6901
6902    begin
6903       if Present (Alias (Proc_Nam)) then
6904          Subp_Decl := Parent (Parent (Alias (Proc_Nam)));
6905       end if;
6906
6907       --  Look for a rewritten subprogram renaming declaration
6908
6909       if Nkind (Subp_Decl) = N_Subprogram_Declaration
6910         and then Present (Original_Node (Subp_Decl))
6911       then
6912          Orig_Node := Original_Node (Subp_Decl);
6913       end if;
6914
6915       --  The rewritten subprogram is actually an entry
6916
6917       if Present (Orig_Node)
6918         and then Nkind (Orig_Node) = N_Subprogram_Renaming_Declaration
6919         and then Is_Entry (Name (Orig_Node))
6920       then
6921          return True;
6922       end if;
6923
6924       return False;
6925    end Is_Renamed_Entry;
6926
6927    ----------------------
6928    -- Is_Selector_Name --
6929    ----------------------
6930
6931    function Is_Selector_Name (N : Node_Id) return Boolean is
6932    begin
6933       if not Is_List_Member (N) then
6934          declare
6935             P : constant Node_Id   := Parent (N);
6936             K : constant Node_Kind := Nkind (P);
6937          begin
6938             return
6939               (K = N_Expanded_Name          or else
6940                K = N_Generic_Association    or else
6941                K = N_Parameter_Association  or else
6942                K = N_Selected_Component)
6943               and then Selector_Name (P) = N;
6944          end;
6945
6946       else
6947          declare
6948             L : constant List_Id := List_Containing (N);
6949             P : constant Node_Id := Parent (L);
6950          begin
6951             return (Nkind (P) = N_Discriminant_Association
6952                      and then Selector_Names (P) = L)
6953               or else
6954                    (Nkind (P) = N_Component_Association
6955                      and then Choices (P) = L);
6956          end;
6957       end if;
6958    end Is_Selector_Name;
6959
6960    ------------------
6961    -- Is_Statement --
6962    ------------------
6963
6964    function Is_Statement (N : Node_Id) return Boolean is
6965    begin
6966       return
6967         Nkind (N) in N_Statement_Other_Than_Procedure_Call
6968           or else Nkind (N) = N_Procedure_Call_Statement;
6969    end Is_Statement;
6970
6971    ---------------------------------
6972    -- Is_Synchronized_Tagged_Type --
6973    ---------------------------------
6974
6975    function Is_Synchronized_Tagged_Type (E : Entity_Id) return Boolean is
6976       Kind : constant Entity_Kind := Ekind (Base_Type (E));
6977
6978    begin
6979       --  A task or protected type derived from an interface is a tagged type.
6980       --  Such a tagged type is called a synchronized tagged type, as are
6981       --  synchronized interfaces and private extensions whose declaration
6982       --  includes the reserved word synchronized.
6983
6984       return (Is_Tagged_Type (E)
6985                 and then (Kind = E_Task_Type
6986                            or else Kind = E_Protected_Type))
6987             or else
6988              (Is_Interface (E)
6989                 and then Is_Synchronized_Interface (E))
6990             or else
6991              (Ekind (E) = E_Record_Type_With_Private
6992                 and then (Synchronized_Present (Parent (E))
6993                            or else Is_Synchronized_Interface (Etype (E))));
6994    end Is_Synchronized_Tagged_Type;
6995
6996    -----------------
6997    -- Is_Transfer --
6998    -----------------
6999
7000    function Is_Transfer (N : Node_Id) return Boolean is
7001       Kind : constant Node_Kind := Nkind (N);
7002
7003    begin
7004       if Kind = N_Simple_Return_Statement
7005            or else
7006          Kind = N_Extended_Return_Statement
7007            or else
7008          Kind = N_Goto_Statement
7009            or else
7010          Kind = N_Raise_Statement
7011            or else
7012          Kind = N_Requeue_Statement
7013       then
7014          return True;
7015
7016       elsif (Kind = N_Exit_Statement or else Kind in N_Raise_xxx_Error)
7017         and then No (Condition (N))
7018       then
7019          return True;
7020
7021       elsif Kind = N_Procedure_Call_Statement
7022         and then Is_Entity_Name (Name (N))
7023         and then Present (Entity (Name (N)))
7024         and then No_Return (Entity (Name (N)))
7025       then
7026          return True;
7027
7028       elsif Nkind (Original_Node (N)) = N_Raise_Statement then
7029          return True;
7030
7031       else
7032          return False;
7033       end if;
7034    end Is_Transfer;
7035
7036    -------------
7037    -- Is_True --
7038    -------------
7039
7040    function Is_True (U : Uint) return Boolean is
7041    begin
7042       return (U /= 0);
7043    end Is_True;
7044
7045    -------------------
7046    -- Is_Value_Type --
7047    -------------------
7048
7049    function Is_Value_Type (T : Entity_Id) return Boolean is
7050    begin
7051       return VM_Target = CLI_Target
7052         and then Nkind (T) in N_Has_Chars
7053         and then Chars (T) /= No_Name
7054         and then Get_Name_String (Chars (T)) = "valuetype";
7055    end Is_Value_Type;
7056
7057    ---------------------
7058    -- Is_VMS_Operator --
7059    ---------------------
7060
7061    function Is_VMS_Operator (Op : Entity_Id) return Boolean is
7062    begin
7063       return Ekind (Op) = E_Function
7064         and then Is_Intrinsic_Subprogram (Op)
7065         and then Chars (Scope (Scope (Op))) = Name_System
7066         and then OpenVMS_On_Target;
7067    end Is_VMS_Operator;
7068
7069    -----------------
7070    -- Is_Delegate --
7071    -----------------
7072
7073    function Is_Delegate (T : Entity_Id) return Boolean is
7074       Desig_Type : Entity_Id;
7075
7076    begin
7077       if VM_Target /= CLI_Target then
7078          return False;
7079       end if;
7080
7081       --  Access-to-subprograms are delegates in CIL
7082
7083       if Ekind (T) = E_Access_Subprogram_Type then
7084          return True;
7085       end if;
7086
7087       if Ekind (T) not in Access_Kind then
7088
7089          --  A delegate is a managed pointer. If no designated type is defined
7090          --  it means that it's not a delegate.
7091
7092          return False;
7093       end if;
7094
7095       Desig_Type := Etype (Directly_Designated_Type (T));
7096
7097       if not Is_Tagged_Type (Desig_Type) then
7098          return False;
7099       end if;
7100
7101       --  Test if the type is inherited from [mscorlib]System.Delegate
7102
7103       while Etype (Desig_Type) /= Desig_Type loop
7104          if Chars (Scope (Desig_Type)) /= No_Name
7105            and then Is_Imported (Scope (Desig_Type))
7106            and then Get_Name_String (Chars (Scope (Desig_Type))) = "delegate"
7107          then
7108             return True;
7109          end if;
7110
7111          Desig_Type := Etype (Desig_Type);
7112       end loop;
7113
7114       return False;
7115    end Is_Delegate;
7116
7117    -----------------
7118    -- Is_Variable --
7119    -----------------
7120
7121    function Is_Variable (N : Node_Id) return Boolean is
7122
7123       Orig_Node : constant Node_Id := Original_Node (N);
7124       --  We do the test on the original node, since this is basically a test
7125       --  of syntactic categories, so it must not be disturbed by whatever
7126       --  rewriting might have occurred. For example, an aggregate, which is
7127       --  certainly NOT a variable, could be turned into a variable by
7128       --  expansion.
7129
7130       function In_Protected_Function (E : Entity_Id) return Boolean;
7131       --  Within a protected function, the private components of the
7132       --  enclosing protected type are constants. A function nested within
7133       --  a (protected) procedure is not itself protected.
7134
7135       function Is_Variable_Prefix (P : Node_Id) return Boolean;
7136       --  Prefixes can involve implicit dereferences, in which case we
7137       --  must test for the case of a reference of a constant access
7138       --  type, which can never be a variable.
7139
7140       ---------------------------
7141       -- In_Protected_Function --
7142       ---------------------------
7143
7144       function In_Protected_Function (E : Entity_Id) return Boolean is
7145          Prot : constant Entity_Id := Scope (E);
7146          S    : Entity_Id;
7147
7148       begin
7149          if not Is_Protected_Type (Prot) then
7150             return False;
7151          else
7152             S := Current_Scope;
7153             while Present (S) and then S /= Prot loop
7154                if Ekind (S) = E_Function
7155                  and then Scope (S) = Prot
7156                then
7157                   return True;
7158                end if;
7159
7160                S := Scope (S);
7161             end loop;
7162
7163             return False;
7164          end if;
7165       end In_Protected_Function;
7166
7167       ------------------------
7168       -- Is_Variable_Prefix --
7169       ------------------------
7170
7171       function Is_Variable_Prefix (P : Node_Id) return Boolean is
7172       begin
7173          if Is_Access_Type (Etype (P)) then
7174             return not Is_Access_Constant (Root_Type (Etype (P)));
7175
7176          --  For the case of an indexed component whose prefix has a packed
7177          --  array type, the prefix has been rewritten into a type conversion.
7178          --  Determine variable-ness from the converted expression.
7179
7180          elsif Nkind (P) = N_Type_Conversion
7181            and then not Comes_From_Source (P)
7182            and then Is_Array_Type (Etype (P))
7183            and then Is_Packed (Etype (P))
7184          then
7185             return Is_Variable (Expression (P));
7186
7187          else
7188             return Is_Variable (P);
7189          end if;
7190       end Is_Variable_Prefix;
7191
7192    --  Start of processing for Is_Variable
7193
7194    begin
7195       --  Definitely OK if Assignment_OK is set. Since this is something that
7196       --  only gets set for expanded nodes, the test is on N, not Orig_Node.
7197
7198       if Nkind (N) in N_Subexpr and then Assignment_OK (N) then
7199          return True;
7200
7201       --  Normally we go to the original node, but there is one exception
7202       --  where we use the rewritten node, namely when it is an explicit
7203       --  dereference. The generated code may rewrite a prefix which is an
7204       --  access type with an explicit dereference. The dereference is a
7205       --  variable, even though the original node may not be (since it could
7206       --  be a constant of the access type).
7207
7208       --  In Ada 2005 we have a further case to consider: the prefix may be
7209       --  a function call given in prefix notation. The original node appears
7210       --  to be a selected component, but we need to examine the call.
7211
7212       elsif Nkind (N) = N_Explicit_Dereference
7213         and then Nkind (Orig_Node) /= N_Explicit_Dereference
7214         and then Present (Etype (Orig_Node))
7215         and then Is_Access_Type (Etype (Orig_Node))
7216       then
7217          --  Note that if the prefix is an explicit dereference that does not
7218          --  come from source, we must check for a rewritten function call in
7219          --  prefixed notation before other forms of rewriting, to prevent a
7220          --  compiler crash.
7221
7222          return
7223            (Nkind (Orig_Node) = N_Function_Call
7224              and then not Is_Access_Constant (Etype (Prefix (N))))
7225            or else
7226              Is_Variable_Prefix (Original_Node (Prefix (N)));
7227
7228       --  A function call is never a variable
7229
7230       elsif Nkind (N) = N_Function_Call then
7231          return False;
7232
7233       --  All remaining checks use the original node
7234
7235       elsif Is_Entity_Name (Orig_Node)
7236         and then Present (Entity (Orig_Node))
7237       then
7238          declare
7239             E : constant Entity_Id := Entity (Orig_Node);
7240             K : constant Entity_Kind := Ekind (E);
7241
7242          begin
7243             return (K = E_Variable
7244                       and then Nkind (Parent (E)) /= N_Exception_Handler)
7245               or else  (K = E_Component
7246                           and then not In_Protected_Function (E))
7247               or else  K = E_Out_Parameter
7248               or else  K = E_In_Out_Parameter
7249               or else  K = E_Generic_In_Out_Parameter
7250
7251                --  Current instance of type:
7252
7253               or else (Is_Type (E) and then In_Open_Scopes (E))
7254               or else (Is_Incomplete_Or_Private_Type (E)
7255                         and then In_Open_Scopes (Full_View (E)));
7256          end;
7257
7258       else
7259          case Nkind (Orig_Node) is
7260             when N_Indexed_Component | N_Slice =>
7261                return Is_Variable_Prefix (Prefix (Orig_Node));
7262
7263             when N_Selected_Component =>
7264                return Is_Variable_Prefix (Prefix (Orig_Node))
7265                  and then Is_Variable (Selector_Name (Orig_Node));
7266
7267             --  For an explicit dereference, the type of the prefix cannot
7268             --  be an access to constant or an access to subprogram.
7269
7270             when N_Explicit_Dereference =>
7271                declare
7272                   Typ : constant Entity_Id := Etype (Prefix (Orig_Node));
7273                begin
7274                   return Is_Access_Type (Typ)
7275                     and then not Is_Access_Constant (Root_Type (Typ))
7276                     and then Ekind (Typ) /= E_Access_Subprogram_Type;
7277                end;
7278
7279             --  The type conversion is the case where we do not deal with the
7280             --  context dependent special case of an actual parameter. Thus
7281             --  the type conversion is only considered a variable for the
7282             --  purposes of this routine if the target type is tagged. However,
7283             --  a type conversion is considered to be a variable if it does not
7284             --  come from source (this deals for example with the conversions
7285             --  of expressions to their actual subtypes).
7286
7287             when N_Type_Conversion =>
7288                return Is_Variable (Expression (Orig_Node))
7289                  and then
7290                    (not Comes_From_Source (Orig_Node)
7291                       or else
7292                         (Is_Tagged_Type (Etype (Subtype_Mark (Orig_Node)))
7293                           and then
7294                          Is_Tagged_Type (Etype (Expression (Orig_Node)))));
7295
7296             --  GNAT allows an unchecked type conversion as a variable. This
7297             --  only affects the generation of internal expanded code, since
7298             --  calls to instantiations of Unchecked_Conversion are never
7299             --  considered variables (since they are function calls).
7300             --  This is also true for expression actions.
7301
7302             when N_Unchecked_Type_Conversion =>
7303                return Is_Variable (Expression (Orig_Node));
7304
7305             when others =>
7306                return False;
7307          end case;
7308       end if;
7309    end Is_Variable;
7310
7311    ---------------------------
7312    -- Is_Visibly_Controlled --
7313    ---------------------------
7314
7315    function Is_Visibly_Controlled (T : Entity_Id) return Boolean is
7316       Root : constant Entity_Id := Root_Type (T);
7317    begin
7318       return Chars (Scope (Root)) = Name_Finalization
7319         and then Chars (Scope (Scope (Root))) = Name_Ada
7320         and then Scope (Scope (Scope (Root))) = Standard_Standard;
7321    end Is_Visibly_Controlled;
7322
7323    ------------------------
7324    -- Is_Volatile_Object --
7325    ------------------------
7326
7327    function Is_Volatile_Object (N : Node_Id) return Boolean is
7328
7329       function Object_Has_Volatile_Components (N : Node_Id) return Boolean;
7330       --  Determines if given object has volatile components
7331
7332       function Is_Volatile_Prefix (N : Node_Id) return Boolean;
7333       --  If prefix is an implicit dereference, examine designated type
7334
7335       ------------------------
7336       -- Is_Volatile_Prefix --
7337       ------------------------
7338
7339       function Is_Volatile_Prefix (N : Node_Id) return Boolean is
7340          Typ  : constant Entity_Id := Etype (N);
7341
7342       begin
7343          if Is_Access_Type (Typ) then
7344             declare
7345                Dtyp : constant Entity_Id := Designated_Type (Typ);
7346
7347             begin
7348                return Is_Volatile (Dtyp)
7349                  or else Has_Volatile_Components (Dtyp);
7350             end;
7351
7352          else
7353             return Object_Has_Volatile_Components (N);
7354          end if;
7355       end Is_Volatile_Prefix;
7356
7357       ------------------------------------
7358       -- Object_Has_Volatile_Components --
7359       ------------------------------------
7360
7361       function Object_Has_Volatile_Components (N : Node_Id) return Boolean is
7362          Typ : constant Entity_Id := Etype (N);
7363
7364       begin
7365          if Is_Volatile (Typ)
7366            or else Has_Volatile_Components (Typ)
7367          then
7368             return True;
7369
7370          elsif Is_Entity_Name (N)
7371            and then (Has_Volatile_Components (Entity (N))
7372                       or else Is_Volatile (Entity (N)))
7373          then
7374             return True;
7375
7376          elsif Nkind (N) = N_Indexed_Component
7377            or else Nkind (N) = N_Selected_Component
7378          then
7379             return Is_Volatile_Prefix (Prefix (N));
7380
7381          else
7382             return False;
7383          end if;
7384       end Object_Has_Volatile_Components;
7385
7386    --  Start of processing for Is_Volatile_Object
7387
7388    begin
7389       if Is_Volatile (Etype (N))
7390         or else (Is_Entity_Name (N) and then Is_Volatile (Entity (N)))
7391       then
7392          return True;
7393
7394       elsif Nkind (N) = N_Indexed_Component
7395         or else Nkind (N) = N_Selected_Component
7396       then
7397          return Is_Volatile_Prefix (Prefix (N));
7398
7399       else
7400          return False;
7401       end if;
7402    end Is_Volatile_Object;
7403
7404    -------------------------
7405    -- Kill_Current_Values --
7406    -------------------------
7407
7408    procedure Kill_Current_Values
7409      (Ent                  : Entity_Id;
7410       Last_Assignment_Only : Boolean := False)
7411    is
7412    begin
7413       --  ??? do we have to worry about clearing cached checks?
7414
7415       if Is_Assignable (Ent) then
7416          Set_Last_Assignment (Ent, Empty);
7417       end if;
7418
7419       if Is_Object (Ent) then
7420          if not Last_Assignment_Only then
7421             Kill_Checks (Ent);
7422             Set_Current_Value (Ent, Empty);
7423
7424             if not Can_Never_Be_Null (Ent) then
7425                Set_Is_Known_Non_Null (Ent, False);
7426             end if;
7427
7428             Set_Is_Known_Null (Ent, False);
7429
7430             --  Reset Is_Known_Valid unless type is always valid, or if we have
7431             --  a loop parameter (loop parameters are always valid, since their
7432             --  bounds are defined by the bounds given in the loop header).
7433
7434             if not Is_Known_Valid (Etype (Ent))
7435               and then Ekind (Ent) /= E_Loop_Parameter
7436             then
7437                Set_Is_Known_Valid (Ent, False);
7438             end if;
7439          end if;
7440       end if;
7441    end Kill_Current_Values;
7442
7443    procedure Kill_Current_Values (Last_Assignment_Only : Boolean := False) is
7444       S : Entity_Id;
7445
7446       procedure Kill_Current_Values_For_Entity_Chain (E : Entity_Id);
7447       --  Clear current value for entity E and all entities chained to E
7448
7449       ------------------------------------------
7450       -- Kill_Current_Values_For_Entity_Chain --
7451       ------------------------------------------
7452
7453       procedure Kill_Current_Values_For_Entity_Chain (E : Entity_Id) is
7454          Ent : Entity_Id;
7455       begin
7456          Ent := E;
7457          while Present (Ent) loop
7458             Kill_Current_Values (Ent, Last_Assignment_Only);
7459             Next_Entity (Ent);
7460          end loop;
7461       end Kill_Current_Values_For_Entity_Chain;
7462
7463    --  Start of processing for Kill_Current_Values
7464
7465    begin
7466       --  Kill all saved checks, a special case of killing saved values
7467
7468       if not Last_Assignment_Only then
7469          Kill_All_Checks;
7470       end if;
7471
7472       --  Loop through relevant scopes, which includes the current scope and
7473       --  any parent scopes if the current scope is a block or a package.
7474
7475       S := Current_Scope;
7476       Scope_Loop : loop
7477
7478          --  Clear current values of all entities in current scope
7479
7480          Kill_Current_Values_For_Entity_Chain (First_Entity (S));
7481
7482          --  If scope is a package, also clear current values of all
7483          --  private entities in the scope.
7484
7485          if Is_Package_Or_Generic_Package (S)
7486            or else Is_Concurrent_Type (S)
7487          then
7488             Kill_Current_Values_For_Entity_Chain (First_Private_Entity (S));
7489          end if;
7490
7491          --  If this is a not a subprogram, deal with parents
7492
7493          if not Is_Subprogram (S) then
7494             S := Scope (S);
7495             exit Scope_Loop when S = Standard_Standard;
7496          else
7497             exit Scope_Loop;
7498          end if;
7499       end loop Scope_Loop;
7500    end Kill_Current_Values;
7501
7502    --------------------------
7503    -- Kill_Size_Check_Code --
7504    --------------------------
7505
7506    procedure Kill_Size_Check_Code (E : Entity_Id) is
7507    begin
7508       if (Ekind (E) = E_Constant or else Ekind (E) = E_Variable)
7509         and then Present (Size_Check_Code (E))
7510       then
7511          Remove (Size_Check_Code (E));
7512          Set_Size_Check_Code (E, Empty);
7513       end if;
7514    end Kill_Size_Check_Code;
7515
7516    --------------------------
7517    -- Known_To_Be_Assigned --
7518    --------------------------
7519
7520    function Known_To_Be_Assigned (N : Node_Id) return Boolean is
7521       P : constant Node_Id := Parent (N);
7522
7523    begin
7524       case Nkind (P) is
7525
7526          --  Test left side of assignment
7527
7528          when N_Assignment_Statement =>
7529             return N = Name (P);
7530
7531             --  Function call arguments are never lvalues
7532
7533          when N_Function_Call =>
7534             return False;
7535
7536          --  Positional parameter for procedure or accept call
7537
7538          when N_Procedure_Call_Statement |
7539               N_Accept_Statement
7540           =>
7541             declare
7542                Proc : Entity_Id;
7543                Form : Entity_Id;
7544                Act  : Node_Id;
7545
7546             begin
7547                Proc := Get_Subprogram_Entity (P);
7548
7549                if No (Proc) then
7550                   return False;
7551                end if;
7552
7553                --  If we are not a list member, something is strange, so
7554                --  be conservative and return False.
7555
7556                if not Is_List_Member (N) then
7557                   return False;
7558                end if;
7559
7560                --  We are going to find the right formal by stepping forward
7561                --  through the formals, as we step backwards in the actuals.
7562
7563                Form := First_Formal (Proc);
7564                Act  := N;
7565                loop
7566                   --  If no formal, something is weird, so be conservative
7567                   --  and return False.
7568
7569                   if No (Form) then
7570                      return False;
7571                   end if;
7572
7573                   Prev (Act);
7574                   exit when No (Act);
7575                   Next_Formal (Form);
7576                end loop;
7577
7578                return Ekind (Form) /= E_In_Parameter;
7579             end;
7580
7581          --  Named parameter for procedure or accept call
7582
7583          when N_Parameter_Association =>
7584             declare
7585                Proc : Entity_Id;
7586                Form : Entity_Id;
7587
7588             begin
7589                Proc := Get_Subprogram_Entity (Parent (P));
7590
7591                if No (Proc) then
7592                   return False;
7593                end if;
7594
7595                --  Loop through formals to find the one that matches
7596
7597                Form := First_Formal (Proc);
7598                loop
7599                   --  If no matching formal, that's peculiar, some kind of
7600                   --  previous error, so return False to be conservative.
7601
7602                   if No (Form) then
7603                      return False;
7604                   end if;
7605
7606                   --  Else test for match
7607
7608                   if Chars (Form) = Chars (Selector_Name (P)) then
7609                      return Ekind (Form) /= E_In_Parameter;
7610                   end if;
7611
7612                   Next_Formal (Form);
7613                end loop;
7614             end;
7615
7616          --  Test for appearing in a conversion that itself appears
7617          --  in an lvalue context, since this should be an lvalue.
7618
7619          when N_Type_Conversion =>
7620             return Known_To_Be_Assigned (P);
7621
7622          --  All other references are definitely not known to be modifications
7623
7624          when others =>
7625             return False;
7626
7627       end case;
7628    end Known_To_Be_Assigned;
7629
7630    -------------------
7631    -- May_Be_Lvalue --
7632    -------------------
7633
7634    function May_Be_Lvalue (N : Node_Id) return Boolean is
7635       P : constant Node_Id := Parent (N);
7636
7637    begin
7638       case Nkind (P) is
7639
7640          --  Test left side of assignment
7641
7642          when N_Assignment_Statement =>
7643             return N = Name (P);
7644
7645          --  Test prefix of component or attribute. Note that the prefix of an
7646          --  explicit or implicit dereference cannot be an l-value.
7647
7648          when N_Attribute_Reference =>
7649             return N = Prefix (P)
7650               and then Name_Implies_Lvalue_Prefix (Attribute_Name (P));
7651
7652          --  For an expanded name, the name is an lvalue if the expanded name
7653          --  is an lvalue, but the prefix is never an lvalue, since it is just
7654          --  the scope where the name is found.
7655
7656          when N_Expanded_Name        =>
7657             if N = Prefix (P) then
7658                return May_Be_Lvalue (P);
7659             else
7660                return False;
7661             end if;
7662
7663          --  For a selected component A.B, A is certainly an lvalue if A.B is.
7664          --  B is a little interesting, if we have A.B := 3, there is some
7665          --  discussion as to whether B is an lvalue or not, we choose to say
7666          --  it is. Note however that A is not an lvalue if it is of an access
7667          --  type since this is an implicit dereference.
7668
7669          when N_Selected_Component   =>
7670             if N = Prefix (P)
7671               and then Present (Etype (N))
7672               and then Is_Access_Type (Etype (N))
7673             then
7674                return False;
7675             else
7676                return May_Be_Lvalue (P);
7677             end if;
7678
7679          --  For an indexed component or slice, the index or slice bounds is
7680          --  never an lvalue. The prefix is an lvalue if the indexed component
7681          --  or slice is an lvalue, except if it is an access type, where we
7682          --  have an implicit dereference.
7683
7684          when N_Indexed_Component    =>
7685             if N /= Prefix (P)
7686               or else (Present (Etype (N)) and then Is_Access_Type (Etype (N)))
7687             then
7688                return False;
7689             else
7690                return May_Be_Lvalue (P);
7691             end if;
7692
7693          --  Prefix of a reference is an lvalue if the reference is an lvalue
7694
7695          when N_Reference            =>
7696             return May_Be_Lvalue (P);
7697
7698          --  Prefix of explicit dereference is never an lvalue
7699
7700          when N_Explicit_Dereference =>
7701             return False;
7702
7703          --  Function call arguments are never lvalues
7704
7705          when N_Function_Call =>
7706             return False;
7707
7708          --  Positional parameter for procedure, entry,  or accept call
7709
7710          when N_Procedure_Call_Statement |
7711               N_Entry_Call_Statement     |
7712               N_Accept_Statement
7713          =>
7714             declare
7715                Proc : Entity_Id;
7716                Form : Entity_Id;
7717                Act  : Node_Id;
7718
7719             begin
7720                Proc := Get_Subprogram_Entity (P);
7721
7722                if No (Proc) then
7723                   return True;
7724                end if;
7725
7726                --  If we are not a list member, something is strange, so
7727                --  be conservative and return True.
7728
7729                if not Is_List_Member (N) then
7730                   return True;
7731                end if;
7732
7733                --  We are going to find the right formal by stepping forward
7734                --  through the formals, as we step backwards in the actuals.
7735
7736                Form := First_Formal (Proc);
7737                Act  := N;
7738                loop
7739                   --  If no formal, something is weird, so be conservative
7740                   --  and return True.
7741
7742                   if No (Form) then
7743                      return True;
7744                   end if;
7745
7746                   Prev (Act);
7747                   exit when No (Act);
7748                   Next_Formal (Form);
7749                end loop;
7750
7751                return Ekind (Form) /= E_In_Parameter;
7752             end;
7753
7754          --  Named parameter for procedure or accept call
7755
7756          when N_Parameter_Association =>
7757             declare
7758                Proc : Entity_Id;
7759                Form : Entity_Id;
7760
7761             begin
7762                Proc := Get_Subprogram_Entity (Parent (P));
7763
7764                if No (Proc) then
7765                   return True;
7766                end if;
7767
7768                --  Loop through formals to find the one that matches
7769
7770                Form := First_Formal (Proc);
7771                loop
7772                   --  If no matching formal, that's peculiar, some kind of
7773                   --  previous error, so return True to be conservative.
7774
7775                   if No (Form) then
7776                      return True;
7777                   end if;
7778
7779                   --  Else test for match
7780
7781                   if Chars (Form) = Chars (Selector_Name (P)) then
7782                      return Ekind (Form) /= E_In_Parameter;
7783                   end if;
7784
7785                   Next_Formal (Form);
7786                end loop;
7787             end;
7788
7789          --  Test for appearing in a conversion that itself appears in an
7790          --  lvalue context, since this should be an lvalue.
7791
7792          when N_Type_Conversion =>
7793             return May_Be_Lvalue (P);
7794
7795          --  Test for appearance in object renaming declaration
7796
7797          when N_Object_Renaming_Declaration =>
7798             return True;
7799
7800          --  All other references are definitely not lvalues
7801
7802          when others =>
7803             return False;
7804
7805       end case;
7806    end May_Be_Lvalue;
7807
7808    -----------------------
7809    -- Mark_Coextensions --
7810    -----------------------
7811
7812    procedure Mark_Coextensions (Context_Nod : Node_Id; Root_Nod : Node_Id) is
7813       Is_Dynamic : Boolean;
7814       --  Indicates whether the context causes nested coextensions to be
7815       --  dynamic or static
7816
7817       function Mark_Allocator (N : Node_Id) return Traverse_Result;
7818       --  Recognize an allocator node and label it as a dynamic coextension
7819
7820       --------------------
7821       -- Mark_Allocator --
7822       --------------------
7823
7824       function Mark_Allocator (N : Node_Id) return Traverse_Result is
7825       begin
7826          if Nkind (N) = N_Allocator then
7827             if Is_Dynamic then
7828                Set_Is_Dynamic_Coextension (N);
7829             else
7830                Set_Is_Static_Coextension (N);
7831             end if;
7832          end if;
7833
7834          return OK;
7835       end Mark_Allocator;
7836
7837       procedure Mark_Allocators is new Traverse_Proc (Mark_Allocator);
7838
7839    --  Start of processing Mark_Coextensions
7840
7841    begin
7842       case Nkind (Context_Nod) is
7843          when N_Assignment_Statement    |
7844               N_Simple_Return_Statement =>
7845             Is_Dynamic := Nkind (Expression (Context_Nod)) = N_Allocator;
7846
7847          when N_Object_Declaration =>
7848             Is_Dynamic := Nkind (Root_Nod) = N_Allocator;
7849
7850          --  This routine should not be called for constructs which may not
7851          --  contain coextensions.
7852
7853          when others =>
7854             raise Program_Error;
7855       end case;
7856
7857       Mark_Allocators (Root_Nod);
7858    end Mark_Coextensions;
7859
7860    ----------------------
7861    -- Needs_One_Actual --
7862    ----------------------
7863
7864    function Needs_One_Actual (E : Entity_Id) return Boolean is
7865       Formal : Entity_Id;
7866
7867    begin
7868       if Ada_Version >= Ada_05
7869         and then Present (First_Formal (E))
7870       then
7871          Formal := Next_Formal (First_Formal (E));
7872          while Present (Formal) loop
7873             if No (Default_Value (Formal)) then
7874                return False;
7875             end if;
7876
7877             Next_Formal (Formal);
7878          end loop;
7879
7880          return True;
7881
7882       else
7883          return False;
7884       end if;
7885    end Needs_One_Actual;
7886
7887    ------------------------
7888    -- New_Copy_List_Tree --
7889    ------------------------
7890
7891    function New_Copy_List_Tree (List : List_Id) return List_Id is
7892       NL : List_Id;
7893       E  : Node_Id;
7894
7895    begin
7896       if List = No_List then
7897          return No_List;
7898
7899       else
7900          NL := New_List;
7901          E := First (List);
7902
7903          while Present (E) loop
7904             Append (New_Copy_Tree (E), NL);
7905             E := Next (E);
7906          end loop;
7907
7908          return NL;
7909       end if;
7910    end New_Copy_List_Tree;
7911
7912    -------------------
7913    -- New_Copy_Tree --
7914    -------------------
7915
7916    use Atree.Unchecked_Access;
7917    use Atree_Private_Part;
7918
7919    --  Our approach here requires a two pass traversal of the tree. The
7920    --  first pass visits all nodes that eventually will be copied looking
7921    --  for defining Itypes. If any defining Itypes are found, then they are
7922    --  copied, and an entry is added to the replacement map. In the second
7923    --  phase, the tree is copied, using the replacement map to replace any
7924    --  Itype references within the copied tree.
7925
7926    --  The following hash tables are used if the Map supplied has more
7927    --  than hash threshhold entries to speed up access to the map. If
7928    --  there are fewer entries, then the map is searched sequentially
7929    --  (because setting up a hash table for only a few entries takes
7930    --  more time than it saves.
7931
7932    function New_Copy_Hash (E : Entity_Id) return NCT_Header_Num;
7933    --  Hash function used for hash operations
7934
7935    -------------------
7936    -- New_Copy_Hash --
7937    -------------------
7938
7939    function New_Copy_Hash (E : Entity_Id) return NCT_Header_Num is
7940    begin
7941       return Nat (E) mod (NCT_Header_Num'Last + 1);
7942    end New_Copy_Hash;
7943
7944    ---------------
7945    -- NCT_Assoc --
7946    ---------------
7947
7948    --  The hash table NCT_Assoc associates old entities in the table
7949    --  with their corresponding new entities (i.e. the pairs of entries
7950    --  presented in the original Map argument are Key-Element pairs).
7951
7952    package NCT_Assoc is new Simple_HTable (
7953      Header_Num => NCT_Header_Num,
7954      Element    => Entity_Id,
7955      No_Element => Empty,
7956      Key        => Entity_Id,
7957      Hash       => New_Copy_Hash,
7958      Equal      => Types."=");
7959
7960    ---------------------
7961    -- NCT_Itype_Assoc --
7962    ---------------------
7963
7964    --  The hash table NCT_Itype_Assoc contains entries only for those
7965    --  old nodes which have a non-empty Associated_Node_For_Itype set.
7966    --  The key is the associated node, and the element is the new node
7967    --  itself (NOT the associated node for the new node).
7968
7969    package NCT_Itype_Assoc is new Simple_HTable (
7970      Header_Num => NCT_Header_Num,
7971      Element    => Entity_Id,
7972      No_Element => Empty,
7973      Key        => Entity_Id,
7974      Hash       => New_Copy_Hash,
7975      Equal      => Types."=");
7976
7977    --  Start of processing for New_Copy_Tree function
7978
7979    function New_Copy_Tree
7980      (Source    : Node_Id;
7981       Map       : Elist_Id := No_Elist;
7982       New_Sloc  : Source_Ptr := No_Location;
7983       New_Scope : Entity_Id := Empty) return Node_Id
7984    is
7985       Actual_Map : Elist_Id := Map;
7986       --  This is the actual map for the copy. It is initialized with the
7987       --  given elements, and then enlarged as required for Itypes that are
7988       --  copied during the first phase of the copy operation. The visit
7989       --  procedures add elements to this map as Itypes are encountered.
7990       --  The reason we cannot use Map directly, is that it may well be
7991       --  (and normally is) initialized to No_Elist, and if we have mapped
7992       --  entities, we have to reset it to point to a real Elist.
7993
7994       function Assoc (N : Node_Or_Entity_Id) return Node_Id;
7995       --  Called during second phase to map entities into their corresponding
7996       --  copies using Actual_Map. If the argument is not an entity, or is not
7997       --  in Actual_Map, then it is returned unchanged.
7998
7999       procedure Build_NCT_Hash_Tables;
8000       --  Builds hash tables (number of elements >= threshold value)
8001
8002       function Copy_Elist_With_Replacement
8003         (Old_Elist : Elist_Id) return Elist_Id;
8004       --  Called during second phase to copy element list doing replacements
8005
8006       procedure Copy_Itype_With_Replacement (New_Itype : Entity_Id);
8007       --  Called during the second phase to process a copied Itype. The actual
8008       --  copy happened during the first phase (so that we could make the entry
8009       --  in the mapping), but we still have to deal with the descendents of
8010       --  the copied Itype and copy them where necessary.
8011
8012       function Copy_List_With_Replacement (Old_List : List_Id) return List_Id;
8013       --  Called during second phase to copy list doing replacements
8014
8015       function Copy_Node_With_Replacement (Old_Node : Node_Id) return Node_Id;
8016       --  Called during second phase to copy node doing replacements
8017
8018       procedure Visit_Elist (E : Elist_Id);
8019       --  Called during first phase to visit all elements of an Elist
8020
8021       procedure Visit_Field (F : Union_Id; N : Node_Id);
8022       --  Visit a single field, recursing to call Visit_Node or Visit_List
8023       --  if the field is a syntactic descendent of the current node (i.e.
8024       --  its parent is Node N).
8025
8026       procedure Visit_Itype (Old_Itype : Entity_Id);
8027       --  Called during first phase to visit subsidiary fields of a defining
8028       --  Itype, and also create a copy and make an entry in the replacement
8029       --  map for the new copy.
8030
8031       procedure Visit_List (L : List_Id);
8032       --  Called during first phase to visit all elements of a List
8033
8034       procedure Visit_Node (N : Node_Or_Entity_Id);
8035       --  Called during first phase to visit a node and all its subtrees
8036
8037       -----------
8038       -- Assoc --
8039       -----------
8040
8041       function Assoc (N : Node_Or_Entity_Id) return Node_Id is
8042          E   : Elmt_Id;
8043          Ent : Entity_Id;
8044
8045       begin
8046          if not Has_Extension (N) or else No (Actual_Map) then
8047             return N;
8048
8049          elsif NCT_Hash_Tables_Used then
8050             Ent := NCT_Assoc.Get (Entity_Id (N));
8051
8052             if Present (Ent) then
8053                return Ent;
8054             else
8055                return N;
8056             end if;
8057
8058          --  No hash table used, do serial search
8059
8060          else
8061             E := First_Elmt (Actual_Map);
8062             while Present (E) loop
8063                if Node (E) = N then
8064                   return Node (Next_Elmt (E));
8065                else
8066                   E := Next_Elmt (Next_Elmt (E));
8067                end if;
8068             end loop;
8069          end if;
8070
8071          return N;
8072       end Assoc;
8073
8074       ---------------------------
8075       -- Build_NCT_Hash_Tables --
8076       ---------------------------
8077
8078       procedure Build_NCT_Hash_Tables is
8079          Elmt : Elmt_Id;
8080          Ent  : Entity_Id;
8081       begin
8082          if NCT_Hash_Table_Setup then
8083             NCT_Assoc.Reset;
8084             NCT_Itype_Assoc.Reset;
8085          end if;
8086
8087          Elmt := First_Elmt (Actual_Map);
8088          while Present (Elmt) loop
8089             Ent := Node (Elmt);
8090
8091             --  Get new entity, and associate old and new
8092
8093             Next_Elmt (Elmt);
8094             NCT_Assoc.Set (Ent, Node (Elmt));
8095
8096             if Is_Type (Ent) then
8097                declare
8098                   Anode : constant Entity_Id :=
8099                             Associated_Node_For_Itype (Ent);
8100
8101                begin
8102                   if Present (Anode) then
8103
8104                      --  Enter a link between the associated node of the
8105                      --  old Itype and the new Itype, for updating later
8106                      --  when node is copied.
8107
8108                      NCT_Itype_Assoc.Set (Anode, Node (Elmt));
8109                   end if;
8110                end;
8111             end if;
8112
8113             Next_Elmt (Elmt);
8114          end loop;
8115
8116          NCT_Hash_Tables_Used := True;
8117          NCT_Hash_Table_Setup := True;
8118       end Build_NCT_Hash_Tables;
8119
8120       ---------------------------------
8121       -- Copy_Elist_With_Replacement --
8122       ---------------------------------
8123
8124       function Copy_Elist_With_Replacement
8125         (Old_Elist : Elist_Id) return Elist_Id
8126       is
8127          M         : Elmt_Id;
8128          New_Elist : Elist_Id;
8129
8130       begin
8131          if No (Old_Elist) then
8132             return No_Elist;
8133
8134          else
8135             New_Elist := New_Elmt_List;
8136
8137             M := First_Elmt (Old_Elist);
8138             while Present (M) loop
8139                Append_Elmt (Copy_Node_With_Replacement (Node (M)), New_Elist);
8140                Next_Elmt (M);
8141             end loop;
8142          end if;
8143
8144          return New_Elist;
8145       end Copy_Elist_With_Replacement;
8146
8147       ---------------------------------
8148       -- Copy_Itype_With_Replacement --
8149       ---------------------------------
8150
8151       --  This routine exactly parallels its phase one analog Visit_Itype,
8152
8153       procedure Copy_Itype_With_Replacement (New_Itype : Entity_Id) is
8154       begin
8155          --  Translate Next_Entity, Scope and Etype fields, in case they
8156          --  reference entities that have been mapped into copies.
8157
8158          Set_Next_Entity (New_Itype, Assoc (Next_Entity (New_Itype)));
8159          Set_Etype       (New_Itype, Assoc (Etype       (New_Itype)));
8160
8161          if Present (New_Scope) then
8162             Set_Scope    (New_Itype, New_Scope);
8163          else
8164             Set_Scope    (New_Itype, Assoc (Scope       (New_Itype)));
8165          end if;
8166
8167          --  Copy referenced fields
8168
8169          if Is_Discrete_Type (New_Itype) then
8170             Set_Scalar_Range (New_Itype,
8171               Copy_Node_With_Replacement (Scalar_Range (New_Itype)));
8172
8173          elsif Has_Discriminants (Base_Type (New_Itype)) then
8174             Set_Discriminant_Constraint (New_Itype,
8175               Copy_Elist_With_Replacement
8176                 (Discriminant_Constraint (New_Itype)));
8177
8178          elsif Is_Array_Type (New_Itype) then
8179             if Present (First_Index (New_Itype)) then
8180                Set_First_Index (New_Itype,
8181                  First (Copy_List_With_Replacement
8182                          (List_Containing (First_Index (New_Itype)))));
8183             end if;
8184
8185             if Is_Packed (New_Itype) then
8186                Set_Packed_Array_Type (New_Itype,
8187                  Copy_Node_With_Replacement
8188                    (Packed_Array_Type (New_Itype)));
8189             end if;
8190          end if;
8191       end Copy_Itype_With_Replacement;
8192
8193       --------------------------------
8194       -- Copy_List_With_Replacement --
8195       --------------------------------
8196
8197       function Copy_List_With_Replacement
8198         (Old_List : List_Id) return List_Id
8199       is
8200          New_List : List_Id;
8201          E        : Node_Id;
8202
8203       begin
8204          if Old_List = No_List then
8205             return No_List;
8206
8207          else
8208             New_List := Empty_List;
8209
8210             E := First (Old_List);
8211             while Present (E) loop
8212                Append (Copy_Node_With_Replacement (E), New_List);
8213                Next (E);
8214             end loop;
8215
8216             return New_List;
8217          end if;
8218       end Copy_List_With_Replacement;
8219
8220       --------------------------------
8221       -- Copy_Node_With_Replacement --
8222       --------------------------------
8223
8224       function Copy_Node_With_Replacement
8225         (Old_Node : Node_Id) return Node_Id
8226       is
8227          New_Node : Node_Id;
8228
8229          procedure Adjust_Named_Associations
8230            (Old_Node : Node_Id;
8231             New_Node : Node_Id);
8232          --  If a call node has named associations, these are chained through
8233          --  the First_Named_Actual, Next_Named_Actual links. These must be
8234          --  propagated separately to the new parameter list, because these
8235          --  are not syntactic fields.
8236
8237          function Copy_Field_With_Replacement
8238            (Field : Union_Id) return Union_Id;
8239          --  Given Field, which is a field of Old_Node, return a copy of it
8240          --  if it is a syntactic field (i.e. its parent is Node), setting
8241          --  the parent of the copy to poit to New_Node. Otherwise returns
8242          --  the field (possibly mapped if it is an entity).
8243
8244          -------------------------------
8245          -- Adjust_Named_Associations --
8246          -------------------------------
8247
8248          procedure Adjust_Named_Associations
8249            (Old_Node : Node_Id;
8250             New_Node : Node_Id)
8251          is
8252             Old_E : Node_Id;
8253             New_E : Node_Id;
8254
8255             Old_Next : Node_Id;
8256             New_Next : Node_Id;
8257
8258          begin
8259             Old_E := First (Parameter_Associations (Old_Node));
8260             New_E := First (Parameter_Associations (New_Node));
8261             while Present (Old_E) loop
8262                if Nkind (Old_E) = N_Parameter_Association
8263                  and then Present (Next_Named_Actual (Old_E))
8264                then
8265                   if First_Named_Actual (Old_Node)
8266                     =  Explicit_Actual_Parameter (Old_E)
8267                   then
8268                      Set_First_Named_Actual
8269                        (New_Node, Explicit_Actual_Parameter (New_E));
8270                   end if;
8271
8272                   --  Now scan parameter list from the beginning,to locate
8273                   --  next named actual, which can be out of order.
8274
8275                   Old_Next := First (Parameter_Associations (Old_Node));
8276                   New_Next := First (Parameter_Associations (New_Node));
8277
8278                   while Nkind (Old_Next) /= N_Parameter_Association
8279                     or else  Explicit_Actual_Parameter (Old_Next)
8280                       /= Next_Named_Actual (Old_E)
8281                   loop
8282                      Next (Old_Next);
8283                      Next (New_Next);
8284                   end loop;
8285
8286                   Set_Next_Named_Actual
8287                     (New_E, Explicit_Actual_Parameter (New_Next));
8288                end if;
8289
8290                Next (Old_E);
8291                Next (New_E);
8292             end loop;
8293          end Adjust_Named_Associations;
8294
8295          ---------------------------------
8296          -- Copy_Field_With_Replacement --
8297          ---------------------------------
8298
8299          function Copy_Field_With_Replacement
8300            (Field : Union_Id) return Union_Id
8301          is
8302          begin
8303             if Field = Union_Id (Empty) then
8304                return Field;
8305
8306             elsif Field in Node_Range then
8307                declare
8308                   Old_N : constant Node_Id := Node_Id (Field);
8309                   New_N : Node_Id;
8310
8311                begin
8312                   --  If syntactic field, as indicated by the parent pointer
8313                   --  being set, then copy the referenced node recursively.
8314
8315                   if Parent (Old_N) = Old_Node then
8316                      New_N := Copy_Node_With_Replacement (Old_N);
8317
8318                      if New_N /= Old_N then
8319                         Set_Parent (New_N, New_Node);
8320                      end if;
8321
8322                   --  For semantic fields, update possible entity reference
8323                   --  from the replacement map.
8324
8325                   else
8326                      New_N := Assoc (Old_N);
8327                   end if;
8328
8329                   return Union_Id (New_N);
8330                end;
8331
8332             elsif Field in List_Range then
8333                declare
8334                   Old_L : constant List_Id := List_Id (Field);
8335                   New_L : List_Id;
8336
8337                begin
8338                   --  If syntactic field, as indicated by the parent pointer,
8339                   --  then recursively copy the entire referenced list.
8340
8341                   if Parent (Old_L) = Old_Node then
8342                      New_L := Copy_List_With_Replacement (Old_L);
8343                      Set_Parent (New_L, New_Node);
8344
8345                   --  For semantic list, just returned unchanged
8346
8347                   else
8348                      New_L := Old_L;
8349                   end if;
8350
8351                   return Union_Id (New_L);
8352                end;
8353
8354             --  Anything other than a list or a node is returned unchanged
8355
8356             else
8357                return Field;
8358             end if;
8359          end Copy_Field_With_Replacement;
8360
8361       --  Start of processing for Copy_Node_With_Replacement
8362
8363       begin
8364          if Old_Node <= Empty_Or_Error then
8365             return Old_Node;
8366
8367          elsif Has_Extension (Old_Node) then
8368             return Assoc (Old_Node);
8369
8370          else
8371             New_Node := New_Copy (Old_Node);
8372
8373             --  If the node we are copying is the associated node of a
8374             --  previously copied Itype, then adjust the associated node
8375             --  of the copy of that Itype accordingly.
8376
8377             if Present (Actual_Map) then
8378                declare
8379                   E   : Elmt_Id;
8380                   Ent : Entity_Id;
8381
8382                begin
8383                   --  Case of hash table used
8384
8385                   if NCT_Hash_Tables_Used then
8386                      Ent := NCT_Itype_Assoc.Get (Old_Node);
8387
8388                      if Present (Ent) then
8389                         Set_Associated_Node_For_Itype (Ent, New_Node);
8390                      end if;
8391
8392                   --  Case of no hash table used
8393
8394                   else
8395                      E := First_Elmt (Actual_Map);
8396                      while Present (E) loop
8397                         if Is_Itype (Node (E))
8398                           and then
8399                             Old_Node = Associated_Node_For_Itype (Node (E))
8400                         then
8401                            Set_Associated_Node_For_Itype
8402                              (Node (Next_Elmt (E)), New_Node);
8403                         end if;
8404
8405                         E := Next_Elmt (Next_Elmt (E));
8406                      end loop;
8407                   end if;
8408                end;
8409             end if;
8410
8411             --  Recursively copy descendents
8412
8413             Set_Field1
8414               (New_Node, Copy_Field_With_Replacement (Field1 (New_Node)));
8415             Set_Field2
8416               (New_Node, Copy_Field_With_Replacement (Field2 (New_Node)));
8417             Set_Field3
8418               (New_Node, Copy_Field_With_Replacement (Field3 (New_Node)));
8419             Set_Field4
8420               (New_Node, Copy_Field_With_Replacement (Field4 (New_Node)));
8421             Set_Field5
8422               (New_Node, Copy_Field_With_Replacement (Field5 (New_Node)));
8423
8424             --  Adjust Sloc of new node if necessary
8425
8426             if New_Sloc /= No_Location then
8427                Set_Sloc (New_Node, New_Sloc);
8428
8429                --  If we adjust the Sloc, then we are essentially making
8430                --  a completely new node, so the Comes_From_Source flag
8431                --  should be reset to the proper default value.
8432
8433                Nodes.Table (New_Node).Comes_From_Source :=
8434                  Default_Node.Comes_From_Source;
8435             end if;
8436
8437             --  If the node is call and has named associations,
8438             --  set the corresponding links in the copy.
8439
8440             if (Nkind (Old_Node) = N_Function_Call
8441                  or else Nkind (Old_Node) = N_Entry_Call_Statement
8442                  or else
8443                    Nkind (Old_Node) = N_Procedure_Call_Statement)
8444               and then Present (First_Named_Actual (Old_Node))
8445             then
8446                Adjust_Named_Associations (Old_Node, New_Node);
8447             end if;
8448
8449             --  Reset First_Real_Statement for Handled_Sequence_Of_Statements.
8450             --  The replacement mechanism applies to entities, and is not used
8451             --  here. Eventually we may need a more general graph-copying
8452             --  routine. For now, do a sequential search to find desired node.
8453
8454             if Nkind (Old_Node) = N_Handled_Sequence_Of_Statements
8455               and then Present (First_Real_Statement (Old_Node))
8456             then
8457                declare
8458                   Old_F  : constant Node_Id := First_Real_Statement (Old_Node);
8459                   N1, N2 : Node_Id;
8460
8461                begin
8462                   N1 := First (Statements (Old_Node));
8463                   N2 := First (Statements (New_Node));
8464
8465                   while N1 /= Old_F loop
8466                      Next (N1);
8467                      Next (N2);
8468                   end loop;
8469
8470                   Set_First_Real_Statement (New_Node, N2);
8471                end;
8472             end if;
8473          end if;
8474
8475          --  All done, return copied node
8476
8477          return New_Node;
8478       end Copy_Node_With_Replacement;
8479
8480       -----------------
8481       -- Visit_Elist --
8482       -----------------
8483
8484       procedure Visit_Elist (E : Elist_Id) is
8485          Elmt : Elmt_Id;
8486       begin
8487          if Present (E) then
8488             Elmt := First_Elmt (E);
8489
8490             while Elmt /= No_Elmt loop
8491                Visit_Node (Node (Elmt));
8492                Next_Elmt (Elmt);
8493             end loop;
8494          end if;
8495       end Visit_Elist;
8496
8497       -----------------
8498       -- Visit_Field --
8499       -----------------
8500
8501       procedure Visit_Field (F : Union_Id; N : Node_Id) is
8502       begin
8503          if F = Union_Id (Empty) then
8504             return;
8505
8506          elsif F in Node_Range then
8507
8508             --  Copy node if it is syntactic, i.e. its parent pointer is
8509             --  set to point to the field that referenced it (certain
8510             --  Itypes will also meet this criterion, which is fine, since
8511             --  these are clearly Itypes that do need to be copied, since
8512             --  we are copying their parent.)
8513
8514             if Parent (Node_Id (F)) = N then
8515                Visit_Node (Node_Id (F));
8516                return;
8517
8518             --  Another case, if we are pointing to an Itype, then we want
8519             --  to copy it if its associated node is somewhere in the tree
8520             --  being copied.
8521
8522             --  Note: the exclusion of self-referential copies is just an
8523             --  optimization, since the search of the already copied list
8524             --  would catch it, but it is a common case (Etype pointing
8525             --  to itself for an Itype that is a base type).
8526
8527             elsif Has_Extension (Node_Id (F))
8528               and then Is_Itype (Entity_Id (F))
8529               and then Node_Id (F) /= N
8530             then
8531                declare
8532                   P : Node_Id;
8533
8534                begin
8535                   P := Associated_Node_For_Itype (Node_Id (F));
8536                   while Present (P) loop
8537                      if P = Source then
8538                         Visit_Node (Node_Id (F));
8539                         return;
8540                      else
8541                         P := Parent (P);
8542                      end if;
8543                   end loop;
8544
8545                   --  An Itype whose parent is not being copied definitely
8546                   --  should NOT be copied, since it does not belong in any
8547                   --  sense to the copied subtree.
8548
8549                   return;
8550                end;
8551             end if;
8552
8553          elsif F in List_Range
8554            and then Parent (List_Id (F)) = N
8555          then
8556             Visit_List (List_Id (F));
8557             return;
8558          end if;
8559       end Visit_Field;
8560
8561       -----------------
8562       -- Visit_Itype --
8563       -----------------
8564
8565       procedure Visit_Itype (Old_Itype : Entity_Id) is
8566          New_Itype : Entity_Id;
8567          E         : Elmt_Id;
8568          Ent       : Entity_Id;
8569
8570       begin
8571          --  Itypes that describe the designated type of access to subprograms
8572          --  have the structure of subprogram declarations, with signatures,
8573          --  etc. Either we duplicate the signatures completely, or choose to
8574          --  share such itypes, which is fine because their elaboration will
8575          --  have no side effects.
8576
8577          if Ekind (Old_Itype) = E_Subprogram_Type then
8578             return;
8579          end if;
8580
8581          New_Itype := New_Copy (Old_Itype);
8582
8583          --  The new Itype has all the attributes of the old one, and
8584          --  we just copy the contents of the entity. However, the back-end
8585          --  needs different names for debugging purposes, so we create a
8586          --  new internal name for it in all cases.
8587
8588          Set_Chars (New_Itype, New_Internal_Name ('T'));
8589
8590          --  If our associated node is an entity that has already been copied,
8591          --  then set the associated node of the copy to point to the right
8592          --  copy. If we have copied an Itype that is itself the associated
8593          --  node of some previously copied Itype, then we set the right
8594          --  pointer in the other direction.
8595
8596          if Present (Actual_Map) then
8597
8598             --  Case of hash tables used
8599
8600             if NCT_Hash_Tables_Used then
8601
8602                Ent := NCT_Assoc.Get (Associated_Node_For_Itype (Old_Itype));
8603
8604                if Present (Ent) then
8605                   Set_Associated_Node_For_Itype (New_Itype, Ent);
8606                end if;
8607
8608                Ent := NCT_Itype_Assoc.Get (Old_Itype);
8609                if Present (Ent) then
8610                   Set_Associated_Node_For_Itype (Ent, New_Itype);
8611
8612                --  If the hash table has no association for this Itype and
8613                --  its associated node, enter one now.
8614
8615                else
8616                   NCT_Itype_Assoc.Set
8617                     (Associated_Node_For_Itype (Old_Itype), New_Itype);
8618                end if;
8619
8620             --  Case of hash tables not used
8621
8622             else
8623                E := First_Elmt (Actual_Map);
8624                while Present (E) loop
8625                   if Associated_Node_For_Itype (Old_Itype) = Node (E) then
8626                      Set_Associated_Node_For_Itype
8627                        (New_Itype, Node (Next_Elmt (E)));
8628                   end if;
8629
8630                   if Is_Type (Node (E))
8631                     and then
8632                       Old_Itype = Associated_Node_For_Itype (Node (E))
8633                   then
8634                      Set_Associated_Node_For_Itype
8635                        (Node (Next_Elmt (E)), New_Itype);
8636                   end if;
8637
8638                   E := Next_Elmt (Next_Elmt (E));
8639                end loop;
8640             end if;
8641          end if;
8642
8643          if Present (Freeze_Node (New_Itype)) then
8644             Set_Is_Frozen (New_Itype, False);
8645             Set_Freeze_Node (New_Itype, Empty);
8646          end if;
8647
8648          --  Add new association to map
8649
8650          if No (Actual_Map) then
8651             Actual_Map := New_Elmt_List;
8652          end if;
8653
8654          Append_Elmt (Old_Itype, Actual_Map);
8655          Append_Elmt (New_Itype, Actual_Map);
8656
8657          if NCT_Hash_Tables_Used then
8658             NCT_Assoc.Set (Old_Itype, New_Itype);
8659
8660          else
8661             NCT_Table_Entries := NCT_Table_Entries + 1;
8662
8663             if NCT_Table_Entries > NCT_Hash_Threshhold then
8664                Build_NCT_Hash_Tables;
8665             end if;
8666          end if;
8667
8668          --  If a record subtype is simply copied, the entity list will be
8669          --  shared. Thus cloned_Subtype must be set to indicate the sharing.
8670
8671          if Ekind_In (Old_Itype, E_Record_Subtype, E_Class_Wide_Subtype) then
8672             Set_Cloned_Subtype (New_Itype, Old_Itype);
8673          end if;
8674
8675          --  Visit descendents that eventually get copied
8676
8677          Visit_Field (Union_Id (Etype (Old_Itype)), Old_Itype);
8678
8679          if Is_Discrete_Type (Old_Itype) then
8680             Visit_Field (Union_Id (Scalar_Range (Old_Itype)), Old_Itype);
8681
8682          elsif Has_Discriminants (Base_Type (Old_Itype)) then
8683             --  ??? This should involve call to Visit_Field
8684             Visit_Elist (Discriminant_Constraint (Old_Itype));
8685
8686          elsif Is_Array_Type (Old_Itype) then
8687             if Present (First_Index (Old_Itype)) then
8688                Visit_Field (Union_Id (List_Containing
8689                                 (First_Index (Old_Itype))),
8690                             Old_Itype);
8691             end if;
8692
8693             if Is_Packed (Old_Itype) then
8694                Visit_Field (Union_Id (Packed_Array_Type (Old_Itype)),
8695                             Old_Itype);
8696             end if;
8697          end if;
8698       end Visit_Itype;
8699
8700       ----------------
8701       -- Visit_List --
8702       ----------------
8703
8704       procedure Visit_List (L : List_Id) is
8705          N : Node_Id;
8706       begin
8707          if L /= No_List then
8708             N := First (L);
8709
8710             while Present (N) loop
8711                Visit_Node (N);
8712                Next (N);
8713             end loop;
8714          end if;
8715       end Visit_List;
8716
8717       ----------------
8718       -- Visit_Node --
8719       ----------------
8720
8721       procedure Visit_Node (N : Node_Or_Entity_Id) is
8722
8723       --  Start of processing for Visit_Node
8724
8725       begin
8726          --  Handle case of an Itype, which must be copied
8727
8728          if Has_Extension (N)
8729            and then Is_Itype (N)
8730          then
8731             --  Nothing to do if already in the list. This can happen with an
8732             --  Itype entity that appears more than once in the tree.
8733             --  Note that we do not want to visit descendents in this case.
8734
8735             --  Test for already in list when hash table is used
8736
8737             if NCT_Hash_Tables_Used then
8738                if Present (NCT_Assoc.Get (Entity_Id (N))) then
8739                   return;
8740                end if;
8741
8742             --  Test for already in list when hash table not used
8743
8744             else
8745                declare
8746                   E : Elmt_Id;
8747                begin
8748                   if Present (Actual_Map) then
8749                      E := First_Elmt (Actual_Map);
8750                      while Present (E) loop
8751                         if Node (E) = N then
8752                            return;
8753                         else
8754                            E := Next_Elmt (Next_Elmt (E));
8755                         end if;
8756                      end loop;
8757                   end if;
8758                end;
8759             end if;
8760
8761             Visit_Itype (N);
8762          end if;
8763
8764          --  Visit descendents
8765
8766          Visit_Field (Field1 (N), N);
8767          Visit_Field (Field2 (N), N);
8768          Visit_Field (Field3 (N), N);
8769          Visit_Field (Field4 (N), N);
8770          Visit_Field (Field5 (N), N);
8771       end Visit_Node;
8772
8773    --  Start of processing for New_Copy_Tree
8774
8775    begin
8776       Actual_Map := Map;
8777
8778       --  See if we should use hash table
8779
8780       if No (Actual_Map) then
8781          NCT_Hash_Tables_Used := False;
8782
8783       else
8784          declare
8785             Elmt : Elmt_Id;
8786
8787          begin
8788             NCT_Table_Entries := 0;
8789
8790             Elmt := First_Elmt (Actual_Map);
8791             while Present (Elmt) loop
8792                NCT_Table_Entries := NCT_Table_Entries + 1;
8793                Next_Elmt (Elmt);
8794                Next_Elmt (Elmt);
8795             end loop;
8796
8797             if NCT_Table_Entries > NCT_Hash_Threshhold then
8798                Build_NCT_Hash_Tables;
8799             else
8800                NCT_Hash_Tables_Used := False;
8801             end if;
8802          end;
8803       end if;
8804
8805       --  Hash table set up if required, now start phase one by visiting
8806       --  top node (we will recursively visit the descendents).
8807
8808       Visit_Node (Source);
8809
8810       --  Now the second phase of the copy can start. First we process
8811       --  all the mapped entities, copying their descendents.
8812
8813       if Present (Actual_Map) then
8814          declare
8815             Elmt      : Elmt_Id;
8816             New_Itype : Entity_Id;
8817          begin
8818             Elmt := First_Elmt (Actual_Map);
8819             while Present (Elmt) loop
8820                Next_Elmt (Elmt);
8821                New_Itype := Node (Elmt);
8822                Copy_Itype_With_Replacement (New_Itype);
8823                Next_Elmt (Elmt);
8824             end loop;
8825          end;
8826       end if;
8827
8828       --  Now we can copy the actual tree
8829
8830       return Copy_Node_With_Replacement (Source);
8831    end New_Copy_Tree;
8832
8833    -------------------------
8834    -- New_External_Entity --
8835    -------------------------
8836
8837    function New_External_Entity
8838      (Kind         : Entity_Kind;
8839       Scope_Id     : Entity_Id;
8840       Sloc_Value   : Source_Ptr;
8841       Related_Id   : Entity_Id;
8842       Suffix       : Character;
8843       Suffix_Index : Nat := 0;
8844       Prefix       : Character := ' ') return Entity_Id
8845    is
8846       N : constant Entity_Id :=
8847             Make_Defining_Identifier (Sloc_Value,
8848               New_External_Name
8849                 (Chars (Related_Id), Suffix, Suffix_Index, Prefix));
8850
8851    begin
8852       Set_Ekind          (N, Kind);
8853       Set_Is_Internal    (N, True);
8854       Append_Entity      (N, Scope_Id);
8855       Set_Public_Status  (N);
8856
8857       if Kind in Type_Kind then
8858          Init_Size_Align (N);
8859       end if;
8860
8861       return N;
8862    end New_External_Entity;
8863
8864    -------------------------
8865    -- New_Internal_Entity --
8866    -------------------------
8867
8868    function New_Internal_Entity
8869      (Kind       : Entity_Kind;
8870       Scope_Id   : Entity_Id;
8871       Sloc_Value : Source_Ptr;
8872       Id_Char    : Character) return Entity_Id
8873    is
8874       N : constant Entity_Id := Make_Temporary (Sloc_Value, Id_Char);
8875
8876    begin
8877       Set_Ekind          (N, Kind);
8878       Set_Is_Internal    (N, True);
8879       Append_Entity      (N, Scope_Id);
8880
8881       if Kind in Type_Kind then
8882          Init_Size_Align (N);
8883       end if;
8884
8885       return N;
8886    end New_Internal_Entity;
8887
8888    -----------------
8889    -- Next_Actual --
8890    -----------------
8891
8892    function Next_Actual (Actual_Id : Node_Id) return Node_Id is
8893       N  : Node_Id;
8894
8895    begin
8896       --  If we are pointing at a positional parameter, it is a member of a
8897       --  node list (the list of parameters), and the next parameter is the
8898       --  next node on the list, unless we hit a parameter association, then
8899       --  we shift to using the chain whose head is the First_Named_Actual in
8900       --  the parent, and then is threaded using the Next_Named_Actual of the
8901       --  Parameter_Association. All this fiddling is because the original node
8902       --  list is in the textual call order, and what we need is the
8903       --  declaration order.
8904
8905       if Is_List_Member (Actual_Id) then
8906          N := Next (Actual_Id);
8907
8908          if Nkind (N) = N_Parameter_Association then
8909             return First_Named_Actual (Parent (Actual_Id));
8910          else
8911             return N;
8912          end if;
8913
8914       else
8915          return Next_Named_Actual (Parent (Actual_Id));
8916       end if;
8917    end Next_Actual;
8918
8919    procedure Next_Actual (Actual_Id : in out Node_Id) is
8920    begin
8921       Actual_Id := Next_Actual (Actual_Id);
8922    end Next_Actual;
8923
8924    -----------------------
8925    -- Normalize_Actuals --
8926    -----------------------
8927
8928    --  Chain actuals according to formals of subprogram. If there are no named
8929    --  associations, the chain is simply the list of Parameter Associations,
8930    --  since the order is the same as the declaration order. If there are named
8931    --  associations, then the First_Named_Actual field in the N_Function_Call
8932    --  or N_Procedure_Call_Statement node points to the Parameter_Association
8933    --  node for the parameter that comes first in declaration order. The
8934    --  remaining named parameters are then chained in declaration order using
8935    --  Next_Named_Actual.
8936
8937    --  This routine also verifies that the number of actuals is compatible with
8938    --  the number and default values of formals, but performs no type checking
8939    --  (type checking is done by the caller).
8940
8941    --  If the matching succeeds, Success is set to True and the caller proceeds
8942    --  with type-checking. If the match is unsuccessful, then Success is set to
8943    --  False, and the caller attempts a different interpretation, if there is
8944    --  one.
8945
8946    --  If the flag Report is on, the call is not overloaded, and a failure to
8947    --  match can be reported here, rather than in the caller.
8948
8949    procedure Normalize_Actuals
8950      (N       : Node_Id;
8951       S       : Entity_Id;
8952       Report  : Boolean;
8953       Success : out Boolean)
8954    is
8955       Actuals     : constant List_Id := Parameter_Associations (N);
8956       Actual      : Node_Id := Empty;
8957       Formal      : Entity_Id;
8958       Last        : Node_Id := Empty;
8959       First_Named : Node_Id := Empty;
8960       Found       : Boolean;
8961
8962       Formals_To_Match : Integer := 0;
8963       Actuals_To_Match : Integer := 0;
8964
8965       procedure Chain (A : Node_Id);
8966       --  Add named actual at the proper place in the list, using the
8967       --  Next_Named_Actual link.
8968
8969       function Reporting return Boolean;
8970       --  Determines if an error is to be reported. To report an error, we
8971       --  need Report to be True, and also we do not report errors caused
8972       --  by calls to init procs that occur within other init procs. Such
8973       --  errors must always be cascaded errors, since if all the types are
8974       --  declared correctly, the compiler will certainly build decent calls!
8975
8976       -----------
8977       -- Chain --
8978       -----------
8979
8980       procedure Chain (A : Node_Id) is
8981       begin
8982          if No (Last) then
8983
8984             --  Call node points to first actual in list
8985
8986             Set_First_Named_Actual (N, Explicit_Actual_Parameter (A));
8987
8988          else
8989             Set_Next_Named_Actual (Last, Explicit_Actual_Parameter (A));
8990          end if;
8991
8992          Last := A;
8993          Set_Next_Named_Actual (Last, Empty);
8994       end Chain;
8995
8996       ---------------
8997       -- Reporting --
8998       ---------------
8999
9000       function Reporting return Boolean is
9001       begin
9002          if not Report then
9003             return False;
9004
9005          elsif not Within_Init_Proc then
9006             return True;
9007
9008          elsif Is_Init_Proc (Entity (Name (N))) then
9009             return False;
9010
9011          else
9012             return True;
9013          end if;
9014       end Reporting;
9015
9016    --  Start of processing for Normalize_Actuals
9017
9018    begin
9019       if Is_Access_Type (S) then
9020
9021          --  The name in the call is a function call that returns an access
9022          --  to subprogram. The designated type has the list of formals.
9023
9024          Formal := First_Formal (Designated_Type (S));
9025       else
9026          Formal := First_Formal (S);
9027       end if;
9028
9029       while Present (Formal) loop
9030          Formals_To_Match := Formals_To_Match + 1;
9031          Next_Formal (Formal);
9032       end loop;
9033
9034       --  Find if there is a named association, and verify that no positional
9035       --  associations appear after named ones.
9036
9037       if Present (Actuals) then
9038          Actual := First (Actuals);
9039       end if;
9040
9041       while Present (Actual)
9042         and then Nkind (Actual) /= N_Parameter_Association
9043       loop
9044          Actuals_To_Match := Actuals_To_Match + 1;
9045          Next (Actual);
9046       end loop;
9047
9048       if No (Actual) and Actuals_To_Match = Formals_To_Match then
9049
9050          --  Most common case: positional notation, no defaults
9051
9052          Success := True;
9053          return;
9054
9055       elsif Actuals_To_Match > Formals_To_Match then
9056
9057          --  Too many actuals: will not work
9058
9059          if Reporting then
9060             if Is_Entity_Name (Name (N)) then
9061                Error_Msg_N ("too many arguments in call to&", Name (N));
9062             else
9063                Error_Msg_N ("too many arguments in call", N);
9064             end if;
9065          end if;
9066
9067          Success := False;
9068          return;
9069       end if;
9070
9071       First_Named := Actual;
9072
9073       while Present (Actual) loop
9074          if Nkind (Actual) /= N_Parameter_Association then
9075             Error_Msg_N
9076               ("positional parameters not allowed after named ones", Actual);
9077             Success := False;
9078             return;
9079
9080          else
9081             Actuals_To_Match := Actuals_To_Match + 1;
9082          end if;
9083
9084          Next (Actual);
9085       end loop;
9086
9087       if Present (Actuals) then
9088          Actual := First (Actuals);
9089       end if;
9090
9091       Formal := First_Formal (S);
9092       while Present (Formal) loop
9093
9094          --  Match the formals in order. If the corresponding actual is
9095          --  positional, nothing to do. Else scan the list of named actuals
9096          --  to find the one with the right name.
9097
9098          if Present (Actual)
9099            and then Nkind (Actual) /= N_Parameter_Association
9100          then
9101             Next (Actual);
9102             Actuals_To_Match := Actuals_To_Match - 1;
9103             Formals_To_Match := Formals_To_Match - 1;
9104
9105          else
9106             --  For named parameters, search the list of actuals to find
9107             --  one that matches the next formal name.
9108
9109             Actual := First_Named;
9110             Found  := False;
9111             while Present (Actual) loop
9112                if Chars (Selector_Name (Actual)) = Chars (Formal) then
9113                   Found := True;
9114                   Chain (Actual);
9115                   Actuals_To_Match := Actuals_To_Match - 1;
9116                   Formals_To_Match := Formals_To_Match - 1;
9117                   exit;
9118                end if;
9119
9120                Next (Actual);
9121             end loop;
9122
9123             if not Found then
9124                if Ekind (Formal) /= E_In_Parameter
9125                  or else No (Default_Value (Formal))
9126                then
9127                   if Reporting then
9128                      if (Comes_From_Source (S)
9129                           or else Sloc (S) = Standard_Location)
9130                        and then Is_Overloadable (S)
9131                      then
9132                         if No (Actuals)
9133                           and then
9134                            (Nkind (Parent (N)) = N_Procedure_Call_Statement
9135                              or else
9136                            (Nkind (Parent (N)) = N_Function_Call
9137                              or else
9138                             Nkind (Parent (N)) = N_Parameter_Association))
9139                           and then Ekind (S) /= E_Function
9140                         then
9141                            Set_Etype (N, Etype (S));
9142                         else
9143                            Error_Msg_Name_1 := Chars (S);
9144                            Error_Msg_Sloc := Sloc (S);
9145                            Error_Msg_NE
9146                              ("missing argument for parameter & " &
9147                                 "in call to % declared #", N, Formal);
9148                         end if;
9149
9150                      elsif Is_Overloadable (S) then
9151                         Error_Msg_Name_1 := Chars (S);
9152
9153                         --  Point to type derivation that generated the
9154                         --  operation.
9155
9156                         Error_Msg_Sloc := Sloc (Parent (S));
9157
9158                         Error_Msg_NE
9159                           ("missing argument for parameter & " &
9160                              "in call to % (inherited) #", N, Formal);
9161
9162                      else
9163                         Error_Msg_NE
9164                           ("missing argument for parameter &", N, Formal);
9165                      end if;
9166                   end if;
9167
9168                   Success := False;
9169                   return;
9170
9171                else
9172                   Formals_To_Match := Formals_To_Match - 1;
9173                end if;
9174             end if;
9175          end if;
9176
9177          Next_Formal (Formal);
9178       end loop;
9179
9180       if Formals_To_Match = 0 and then Actuals_To_Match = 0 then
9181          Success := True;
9182          return;
9183
9184       else
9185          if Reporting then
9186
9187             --  Find some superfluous named actual that did not get
9188             --  attached to the list of associations.
9189
9190             Actual := First (Actuals);
9191             while Present (Actual) loop
9192                if Nkind (Actual) = N_Parameter_Association
9193                  and then Actual /= Last
9194                  and then No (Next_Named_Actual (Actual))
9195                then
9196                   Error_Msg_N ("unmatched actual & in call",
9197                     Selector_Name (Actual));
9198                   exit;
9199                end if;
9200
9201                Next (Actual);
9202             end loop;
9203          end if;
9204
9205          Success := False;
9206          return;
9207       end if;
9208    end Normalize_Actuals;
9209
9210    --------------------------------
9211    -- Note_Possible_Modification --
9212    --------------------------------
9213
9214    procedure Note_Possible_Modification (N : Node_Id; Sure : Boolean) is
9215       Modification_Comes_From_Source : constant Boolean :=
9216                                          Comes_From_Source (Parent (N));
9217
9218       Ent : Entity_Id;
9219       Exp : Node_Id;
9220
9221    begin
9222       --  Loop to find referenced entity, if there is one
9223
9224       Exp := N;
9225       loop
9226          <<Continue>>
9227          Ent := Empty;
9228
9229          if Is_Entity_Name (Exp) then
9230             Ent := Entity (Exp);
9231
9232             --  If the entity is missing, it is an undeclared identifier,
9233             --  and there is nothing to annotate.
9234
9235             if No (Ent) then
9236                return;
9237             end if;
9238
9239          elsif Nkind (Exp) = N_Explicit_Dereference then
9240             declare
9241                P : constant Node_Id := Prefix (Exp);
9242
9243             begin
9244                if Nkind (P) = N_Selected_Component
9245                  and then Present (
9246                    Entry_Formal (Entity (Selector_Name (P))))
9247                then
9248                   --  Case of a reference to an entry formal
9249
9250                   Ent := Entry_Formal (Entity (Selector_Name (P)));
9251
9252                elsif Nkind (P) = N_Identifier
9253                  and then Nkind (Parent (Entity (P))) = N_Object_Declaration
9254                  and then Present (Expression (Parent (Entity (P))))
9255                  and then Nkind (Expression (Parent (Entity (P))))
9256                    = N_Reference
9257                then
9258                   --  Case of a reference to a value on which side effects have
9259                   --  been removed.
9260
9261                   Exp := Prefix (Expression (Parent (Entity (P))));
9262                   goto Continue;
9263
9264                else
9265                   return;
9266
9267                end if;
9268             end;
9269
9270          elsif     Nkind (Exp) = N_Type_Conversion
9271            or else Nkind (Exp) = N_Unchecked_Type_Conversion
9272          then
9273             Exp := Expression (Exp);
9274             goto Continue;
9275
9276          elsif     Nkind (Exp) = N_Slice
9277            or else Nkind (Exp) = N_Indexed_Component
9278            or else Nkind (Exp) = N_Selected_Component
9279          then
9280             Exp := Prefix (Exp);
9281             goto Continue;
9282
9283          else
9284             return;
9285          end if;
9286
9287          --  Now look for entity being referenced
9288
9289          if Present (Ent) then
9290             if Is_Object (Ent) then
9291                if Comes_From_Source (Exp)
9292                  or else Modification_Comes_From_Source
9293                then
9294                   if Has_Pragma_Unmodified (Ent) then
9295                      Error_Msg_NE ("?pragma Unmodified given for &!", N, Ent);
9296                   end if;
9297
9298                   Set_Never_Set_In_Source (Ent, False);
9299                end if;
9300
9301                Set_Is_True_Constant (Ent, False);
9302                Set_Current_Value    (Ent, Empty);
9303                Set_Is_Known_Null    (Ent, False);
9304
9305                if not Can_Never_Be_Null (Ent) then
9306                   Set_Is_Known_Non_Null (Ent, False);
9307                end if;
9308
9309                --  Follow renaming chain
9310
9311                if (Ekind (Ent) = E_Variable or else Ekind (Ent) = E_Constant)
9312                  and then Present (Renamed_Object (Ent))
9313                then
9314                   Exp := Renamed_Object (Ent);
9315                   goto Continue;
9316                end if;
9317
9318                --  Generate a reference only if the assignment comes from
9319                --  source. This excludes, for example, calls to a dispatching
9320                --  assignment operation when the left-hand side is tagged.
9321
9322                if Modification_Comes_From_Source then
9323                   Generate_Reference (Ent, Exp, 'm');
9324                end if;
9325
9326                Check_Nested_Access (Ent);
9327             end if;
9328
9329             Kill_Checks (Ent);
9330
9331             --  If we are sure this is a modification from source, and we know
9332             --  this modifies a constant, then give an appropriate warning.
9333
9334             if Overlays_Constant (Ent)
9335               and then Modification_Comes_From_Source
9336               and then Sure
9337             then
9338                declare
9339                   A : constant Node_Id := Address_Clause (Ent);
9340                begin
9341                   if Present (A) then
9342                      declare
9343                         Exp : constant Node_Id := Expression (A);
9344                      begin
9345                         if Nkind (Exp) = N_Attribute_Reference
9346                           and then Attribute_Name (Exp) = Name_Address
9347                           and then Is_Entity_Name (Prefix (Exp))
9348                         then
9349                            Error_Msg_Sloc := Sloc (A);
9350                            Error_Msg_NE
9351                              ("constant& may be modified via address clause#?",
9352                               N, Entity (Prefix (Exp)));
9353                         end if;
9354                      end;
9355                   end if;
9356                end;
9357             end if;
9358
9359             return;
9360          end if;
9361       end loop;
9362    end Note_Possible_Modification;
9363
9364    -------------------------
9365    -- Object_Access_Level --
9366    -------------------------
9367
9368    function Object_Access_Level (Obj : Node_Id) return Uint is
9369       E : Entity_Id;
9370
9371    --  Returns the static accessibility level of the view denoted by Obj. Note
9372    --  that the value returned is the result of a call to Scope_Depth. Only
9373    --  scope depths associated with dynamic scopes can actually be returned.
9374    --  Since only relative levels matter for accessibility checking, the fact
9375    --  that the distance between successive levels of accessibility is not
9376    --  always one is immaterial (invariant: if level(E2) is deeper than
9377    --  level(E1), then Scope_Depth(E1) < Scope_Depth(E2)).
9378
9379       function Reference_To (Obj : Node_Id) return Node_Id;
9380       --  An explicit dereference is created when removing side-effects from
9381       --  expressions for constraint checking purposes. In this case a local
9382       --  access type is created for it. The correct access level is that of
9383       --  the original source node. We detect this case by noting that the
9384       --  prefix of the dereference is created by an object declaration whose
9385       --  initial expression is a reference.
9386
9387       ------------------
9388       -- Reference_To --
9389       ------------------
9390
9391       function Reference_To (Obj : Node_Id) return Node_Id is
9392          Pref : constant Node_Id := Prefix (Obj);
9393       begin
9394          if Is_Entity_Name (Pref)
9395            and then Nkind (Parent (Entity (Pref))) = N_Object_Declaration
9396            and then Present (Expression (Parent (Entity (Pref))))
9397            and then Nkind (Expression (Parent (Entity (Pref)))) = N_Reference
9398          then
9399             return (Prefix (Expression (Parent (Entity (Pref)))));
9400          else
9401             return Empty;
9402          end if;
9403       end Reference_To;
9404
9405    --  Start of processing for Object_Access_Level
9406
9407    begin
9408       if Is_Entity_Name (Obj) then
9409          E := Entity (Obj);
9410
9411          if Is_Prival (E) then
9412             E := Prival_Link (E);
9413          end if;
9414
9415          --  If E is a type then it denotes a current instance. For this case
9416          --  we add one to the normal accessibility level of the type to ensure
9417          --  that current instances are treated as always being deeper than
9418          --  than the level of any visible named access type (see 3.10.2(21)).
9419
9420          if Is_Type (E) then
9421             return Type_Access_Level (E) +  1;
9422
9423          elsif Present (Renamed_Object (E)) then
9424             return Object_Access_Level (Renamed_Object (E));
9425
9426          --  Similarly, if E is a component of the current instance of a
9427          --  protected type, any instance of it is assumed to be at a deeper
9428          --  level than the type. For a protected object (whose type is an
9429          --  anonymous protected type) its components are at the same level
9430          --  as the type itself.
9431
9432          elsif not Is_Overloadable (E)
9433            and then Ekind (Scope (E)) = E_Protected_Type
9434            and then Comes_From_Source (Scope (E))
9435          then
9436             return Type_Access_Level (Scope (E)) + 1;
9437
9438          else
9439             return Scope_Depth (Enclosing_Dynamic_Scope (E));
9440          end if;
9441
9442       elsif Nkind (Obj) = N_Selected_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_Indexed_Component then
9450          if Is_Access_Type (Etype (Prefix (Obj))) then
9451             return Type_Access_Level (Etype (Prefix (Obj)));
9452          else
9453             return Object_Access_Level (Prefix (Obj));
9454          end if;
9455
9456       elsif Nkind (Obj) = N_Explicit_Dereference then
9457
9458          --  If the prefix is a selected access discriminant then we make a
9459          --  recursive call on the prefix, which will in turn check the level
9460          --  of the prefix object of the selected discriminant.
9461
9462          if Nkind (Prefix (Obj)) = N_Selected_Component
9463            and then Ekind (Etype (Prefix (Obj))) = E_Anonymous_Access_Type
9464            and then
9465              Ekind (Entity (Selector_Name (Prefix (Obj)))) = E_Discriminant
9466          then
9467             return Object_Access_Level (Prefix (Obj));
9468
9469          elsif not (Comes_From_Source (Obj)) then
9470             declare
9471                Ref : constant Node_Id := Reference_To (Obj);
9472             begin
9473                if Present (Ref) then
9474                   return Object_Access_Level (Ref);
9475                else
9476                   return Type_Access_Level (Etype (Prefix (Obj)));
9477                end if;
9478             end;
9479
9480          else
9481             return Type_Access_Level (Etype (Prefix (Obj)));
9482          end if;
9483
9484       elsif Nkind (Obj) = N_Type_Conversion
9485         or else Nkind (Obj) = N_Unchecked_Type_Conversion
9486       then
9487          return Object_Access_Level (Expression (Obj));
9488
9489       --  Function results are objects, so we get either the access level of
9490       --  the function or, in the case of an indirect call, the level of the
9491       --  access-to-subprogram type.
9492
9493       elsif Nkind (Obj) = N_Function_Call then
9494          if Is_Entity_Name (Name (Obj)) then
9495             return Subprogram_Access_Level (Entity (Name (Obj)));
9496          else
9497             return Type_Access_Level (Etype (Prefix (Name (Obj))));
9498          end if;
9499
9500       --  For convenience we handle qualified expressions, even though
9501       --  they aren't technically object names.
9502
9503       elsif Nkind (Obj) = N_Qualified_Expression then
9504          return Object_Access_Level (Expression (Obj));
9505
9506       --  Otherwise return the scope level of Standard.
9507       --  (If there are cases that fall through
9508       --  to this point they will be treated as
9509       --  having global accessibility for now. ???)
9510
9511       else
9512          return Scope_Depth (Standard_Standard);
9513       end if;
9514    end Object_Access_Level;
9515
9516    -----------------------
9517    -- Private_Component --
9518    -----------------------
9519
9520    function Private_Component (Type_Id : Entity_Id) return Entity_Id is
9521       Ancestor  : constant Entity_Id := Base_Type (Type_Id);
9522
9523       function Trace_Components
9524         (T     : Entity_Id;
9525          Check : Boolean) return Entity_Id;
9526       --  Recursive function that does the work, and checks against circular
9527       --  definition for each subcomponent type.
9528
9529       ----------------------
9530       -- Trace_Components --
9531       ----------------------
9532
9533       function Trace_Components
9534          (T     : Entity_Id;
9535           Check : Boolean) return Entity_Id
9536        is
9537          Btype     : constant Entity_Id := Base_Type (T);
9538          Component : Entity_Id;
9539          P         : Entity_Id;
9540          Candidate : Entity_Id := Empty;
9541
9542       begin
9543          if Check and then Btype = Ancestor then
9544             Error_Msg_N ("circular type definition", Type_Id);
9545             return Any_Type;
9546          end if;
9547
9548          if Is_Private_Type (Btype)
9549            and then not Is_Generic_Type (Btype)
9550          then
9551             if Present (Full_View (Btype))
9552               and then Is_Record_Type (Full_View (Btype))
9553               and then not Is_Frozen (Btype)
9554             then
9555                --  To indicate that the ancestor depends on a private type, the
9556                --  current Btype is sufficient. However, to check for circular
9557                --  definition we must recurse on the full view.
9558
9559                Candidate := Trace_Components (Full_View (Btype), True);
9560
9561                if Candidate = Any_Type then
9562                   return Any_Type;
9563                else
9564                   return Btype;
9565                end if;
9566
9567             else
9568                return Btype;
9569             end if;
9570
9571          elsif Is_Array_Type (Btype) then
9572             return Trace_Components (Component_Type (Btype), True);
9573
9574          elsif Is_Record_Type (Btype) then
9575             Component := First_Entity (Btype);
9576             while Present (Component) loop
9577
9578                --  Skip anonymous types generated by constrained components
9579
9580                if not Is_Type (Component) then
9581                   P := Trace_Components (Etype (Component), True);
9582
9583                   if Present (P) then
9584                      if P = Any_Type then
9585                         return P;
9586                      else
9587                         Candidate := P;
9588                      end if;
9589                   end if;
9590                end if;
9591
9592                Next_Entity (Component);
9593             end loop;
9594
9595             return Candidate;
9596
9597          else
9598             return Empty;
9599          end if;
9600       end Trace_Components;
9601
9602    --  Start of processing for Private_Component
9603
9604    begin
9605       return Trace_Components (Type_Id, False);
9606    end Private_Component;
9607
9608    ---------------------------
9609    -- Primitive_Names_Match --
9610    ---------------------------
9611
9612    function Primitive_Names_Match (E1, E2 : Entity_Id) return Boolean is
9613
9614       function Non_Internal_Name (E : Entity_Id) return Name_Id;
9615       --  Given an internal name, returns the corresponding non-internal name
9616
9617       ------------------------
9618       --  Non_Internal_Name --
9619       ------------------------
9620
9621       function Non_Internal_Name (E : Entity_Id) return Name_Id is
9622       begin
9623          Get_Name_String (Chars (E));
9624          Name_Len := Name_Len - 1;
9625          return Name_Find;
9626       end Non_Internal_Name;
9627
9628    --  Start of processing for Primitive_Names_Match
9629
9630    begin
9631       pragma Assert (Present (E1) and then Present (E2));
9632
9633       return Chars (E1) = Chars (E2)
9634         or else
9635            (not Is_Internal_Name (Chars (E1))
9636               and then Is_Internal_Name (Chars (E2))
9637               and then Non_Internal_Name (E2) = Chars (E1))
9638         or else
9639            (not Is_Internal_Name (Chars (E2))
9640               and then Is_Internal_Name (Chars (E1))
9641               and then Non_Internal_Name (E1) = Chars (E2))
9642         or else
9643            (Is_Predefined_Dispatching_Operation (E1)
9644               and then Is_Predefined_Dispatching_Operation (E2)
9645               and then Same_TSS (E1, E2))
9646         or else
9647            (Is_Init_Proc (E1) and then Is_Init_Proc (E2));
9648    end Primitive_Names_Match;
9649
9650    -----------------------
9651    -- Process_End_Label --
9652    -----------------------
9653
9654    procedure Process_End_Label
9655      (N   : Node_Id;
9656       Typ : Character;
9657       Ent  : Entity_Id)
9658    is
9659       Loc  : Source_Ptr;
9660       Nam  : Node_Id;
9661       Scop : Entity_Id;
9662
9663       Label_Ref : Boolean;
9664       --  Set True if reference to end label itself is required
9665
9666       Endl : Node_Id;
9667       --  Gets set to the operator symbol or identifier that references the
9668       --  entity Ent. For the child unit case, this is the identifier from the
9669       --  designator. For other cases, this is simply Endl.
9670
9671       procedure Generate_Parent_Ref (N : Node_Id; E : Entity_Id);
9672       --  N is an identifier node that appears as a parent unit reference in
9673       --  the case where Ent is a child unit. This procedure generates an
9674       --  appropriate cross-reference entry. E is the corresponding entity.
9675
9676       -------------------------
9677       -- Generate_Parent_Ref --
9678       -------------------------
9679
9680       procedure Generate_Parent_Ref (N : Node_Id; E : Entity_Id) is
9681       begin
9682          --  If names do not match, something weird, skip reference
9683
9684          if Chars (E) = Chars (N) then
9685
9686             --  Generate the reference. We do NOT consider this as a reference
9687             --  for unreferenced symbol purposes.
9688
9689             Generate_Reference (E, N, 'r', Set_Ref => False, Force => True);
9690
9691             if Style_Check then
9692                Style.Check_Identifier (N, E);
9693             end if;
9694          end if;
9695       end Generate_Parent_Ref;
9696
9697    --  Start of processing for Process_End_Label
9698
9699    begin
9700       --  If no node, ignore. This happens in some error situations, and
9701       --  also for some internally generated structures where no end label
9702       --  references are required in any case.
9703
9704       if No (N) then
9705          return;
9706       end if;
9707
9708       --  Nothing to do if no End_Label, happens for internally generated
9709       --  constructs where we don't want an end label reference anyway. Also
9710       --  nothing to do if Endl is a string literal, which means there was
9711       --  some prior error (bad operator symbol)
9712
9713       Endl := End_Label (N);
9714
9715       if No (Endl) or else Nkind (Endl) = N_String_Literal then
9716          return;
9717       end if;
9718
9719       --  Reference node is not in extended main source unit
9720
9721       if not In_Extended_Main_Source_Unit (N) then
9722
9723          --  Generally we do not collect references except for the extended
9724          --  main source unit. The one exception is the 'e' entry for a
9725          --  package spec, where it is useful for a client to have the
9726          --  ending information to define scopes.
9727
9728          if Typ /= 'e' then
9729             return;
9730
9731          else
9732             Label_Ref := False;
9733
9734             --  For this case, we can ignore any parent references, but we
9735             --  need the package name itself for the 'e' entry.
9736
9737             if Nkind (Endl) = N_Designator then
9738                Endl := Identifier (Endl);
9739             end if;
9740          end if;
9741
9742       --  Reference is in extended main source unit
9743
9744       else
9745          Label_Ref := True;
9746
9747          --  For designator, generate references for the parent entries
9748
9749          if Nkind (Endl) = N_Designator then
9750
9751             --  Generate references for the prefix if the END line comes from
9752             --  source (otherwise we do not need these references) We climb the
9753             --  scope stack to find the expected entities.
9754
9755             if Comes_From_Source (Endl) then
9756                Nam  := Name (Endl);
9757                Scop := Current_Scope;
9758                while Nkind (Nam) = N_Selected_Component loop
9759                   Scop := Scope (Scop);
9760                   exit when No (Scop);
9761                   Generate_Parent_Ref (Selector_Name (Nam), Scop);
9762                   Nam := Prefix (Nam);
9763                end loop;
9764
9765                if Present (Scop) then
9766                   Generate_Parent_Ref (Nam, Scope (Scop));
9767                end if;
9768             end if;
9769
9770             Endl := Identifier (Endl);
9771          end if;
9772       end if;
9773
9774       --  If the end label is not for the given entity, then either we have
9775       --  some previous error, or this is a generic instantiation for which
9776       --  we do not need to make a cross-reference in this case anyway. In
9777       --  either case we simply ignore the call.
9778
9779       if Chars (Ent) /= Chars (Endl) then
9780          return;
9781       end if;
9782
9783       --  If label was really there, then generate a normal reference and then
9784       --  adjust the location in the end label to point past the name (which
9785       --  should almost always be the semicolon).
9786
9787       Loc := Sloc (Endl);
9788
9789       if Comes_From_Source (Endl) then
9790
9791          --  If a label reference is required, then do the style check and
9792          --  generate an l-type cross-reference entry for the label
9793
9794          if Label_Ref then
9795             if Style_Check then
9796                Style.Check_Identifier (Endl, Ent);
9797             end if;
9798
9799             Generate_Reference (Ent, Endl, 'l', Set_Ref => False);
9800          end if;
9801
9802          --  Set the location to point past the label (normally this will
9803          --  mean the semicolon immediately following the label). This is
9804          --  done for the sake of the 'e' or 't' entry generated below.
9805
9806          Get_Decoded_Name_String (Chars (Endl));
9807          Set_Sloc (Endl, Sloc (Endl) + Source_Ptr (Name_Len));
9808       end if;
9809
9810       --  Now generate the e/t reference
9811
9812       Generate_Reference (Ent, Endl, Typ, Set_Ref => False, Force => True);
9813
9814       --  Restore Sloc, in case modified above, since we have an identifier
9815       --  and the normal Sloc should be left set in the tree.
9816
9817       Set_Sloc (Endl, Loc);
9818    end Process_End_Label;
9819
9820    ------------------
9821    -- Real_Convert --
9822    ------------------
9823
9824    --  We do the conversion to get the value of the real string by using
9825    --  the scanner, see Sinput for details on use of the internal source
9826    --  buffer for scanning internal strings.
9827
9828    function Real_Convert (S : String) return Node_Id is
9829       Save_Src : constant Source_Buffer_Ptr := Source;
9830       Negative : Boolean;
9831
9832    begin
9833       Source := Internal_Source_Ptr;
9834       Scan_Ptr := 1;
9835
9836       for J in S'Range loop
9837          Source (Source_Ptr (J)) := S (J);
9838       end loop;
9839
9840       Source (S'Length + 1) := EOF;
9841
9842       if Source (Scan_Ptr) = '-' then
9843          Negative := True;
9844          Scan_Ptr := Scan_Ptr + 1;
9845       else
9846          Negative := False;
9847       end if;
9848
9849       Scan;
9850
9851       if Negative then
9852          Set_Realval (Token_Node, UR_Negate (Realval (Token_Node)));
9853       end if;
9854
9855       Source := Save_Src;
9856       return Token_Node;
9857    end Real_Convert;
9858
9859    ------------------------------------
9860    -- References_Generic_Formal_Type --
9861    ------------------------------------
9862
9863    function References_Generic_Formal_Type (N : Node_Id) return Boolean is
9864
9865       function Process (N : Node_Id) return Traverse_Result;
9866       --  Process one node in search for generic formal type
9867
9868       -------------
9869       -- Process --
9870       -------------
9871
9872       function Process (N : Node_Id) return Traverse_Result is
9873       begin
9874          if Nkind (N) in N_Has_Entity then
9875             declare
9876                E : constant Entity_Id := Entity (N);
9877             begin
9878                if Present (E) then
9879                   if Is_Generic_Type (E) then
9880                      return Abandon;
9881                   elsif Present (Etype (E))
9882                     and then Is_Generic_Type (Etype (E))
9883                   then
9884                      return Abandon;
9885                   end if;
9886                end if;
9887             end;
9888          end if;
9889
9890          return Atree.OK;
9891       end Process;
9892
9893       function Traverse is new Traverse_Func (Process);
9894       --  Traverse tree to look for generic type
9895
9896    begin
9897       if Inside_A_Generic then
9898          return Traverse (N) = Abandon;
9899       else
9900          return False;
9901       end if;
9902    end References_Generic_Formal_Type;
9903
9904    --------------------
9905    -- Remove_Homonym --
9906    --------------------
9907
9908    procedure Remove_Homonym (E : Entity_Id) is
9909       Prev  : Entity_Id := Empty;
9910       H     : Entity_Id;
9911
9912    begin
9913       if E = Current_Entity (E) then
9914          if Present (Homonym (E)) then
9915             Set_Current_Entity (Homonym (E));
9916          else
9917             Set_Name_Entity_Id (Chars (E), Empty);
9918          end if;
9919       else
9920          H := Current_Entity (E);
9921          while Present (H) and then H /= E loop
9922             Prev := H;
9923             H    := Homonym (H);
9924          end loop;
9925
9926          Set_Homonym (Prev, Homonym (E));
9927       end if;
9928    end Remove_Homonym;
9929
9930    ---------------------
9931    -- Rep_To_Pos_Flag --
9932    ---------------------
9933
9934    function Rep_To_Pos_Flag (E : Entity_Id; Loc : Source_Ptr) return Node_Id is
9935    begin
9936       return New_Occurrence_Of
9937                (Boolean_Literals (not Range_Checks_Suppressed (E)), Loc);
9938    end Rep_To_Pos_Flag;
9939
9940    --------------------
9941    -- Require_Entity --
9942    --------------------
9943
9944    procedure Require_Entity (N : Node_Id) is
9945    begin
9946       if Is_Entity_Name (N) and then No (Entity (N)) then
9947          if Total_Errors_Detected /= 0 then
9948             Set_Entity (N, Any_Id);
9949          else
9950             raise Program_Error;
9951          end if;
9952       end if;
9953    end Require_Entity;
9954
9955    ------------------------------
9956    -- Requires_Transient_Scope --
9957    ------------------------------
9958
9959    --  A transient scope is required when variable-sized temporaries are
9960    --  allocated in the primary or secondary stack, or when finalization
9961    --  actions must be generated before the next instruction.
9962
9963    function Requires_Transient_Scope (Id : Entity_Id) return Boolean is
9964       Typ : constant Entity_Id := Underlying_Type (Id);
9965
9966    --  Start of processing for Requires_Transient_Scope
9967
9968    begin
9969       --  This is a private type which is not completed yet. This can only
9970       --  happen in a default expression (of a formal parameter or of a
9971       --  record component). Do not expand transient scope in this case
9972
9973       if No (Typ) then
9974          return False;
9975
9976       --  Do not expand transient scope for non-existent procedure return
9977
9978       elsif Typ = Standard_Void_Type then
9979          return False;
9980
9981       --  Elementary types do not require a transient scope
9982
9983       elsif Is_Elementary_Type (Typ) then
9984          return False;
9985
9986       --  Generally, indefinite subtypes require a transient scope, since the
9987       --  back end cannot generate temporaries, since this is not a valid type
9988       --  for declaring an object. It might be possible to relax this in the
9989       --  future, e.g. by declaring the maximum possible space for the type.
9990
9991       elsif Is_Indefinite_Subtype (Typ) then
9992          return True;
9993
9994       --  Functions returning tagged types may dispatch on result so their
9995       --  returned value is allocated on the secondary stack. Controlled
9996       --  type temporaries need finalization.
9997
9998       elsif Is_Tagged_Type (Typ)
9999         or else Has_Controlled_Component (Typ)
10000       then
10001          return not Is_Value_Type (Typ);
10002
10003       --  Record type
10004
10005       elsif Is_Record_Type (Typ) then
10006          declare
10007             Comp : Entity_Id;
10008          begin
10009             Comp := First_Entity (Typ);
10010             while Present (Comp) loop
10011                if Ekind (Comp) = E_Component
10012                   and then Requires_Transient_Scope (Etype (Comp))
10013                then
10014                   return True;
10015                else
10016                   Next_Entity (Comp);
10017                end if;
10018             end loop;
10019          end;
10020
10021          return False;
10022
10023       --  String literal types never require transient scope
10024
10025       elsif Ekind (Typ) = E_String_Literal_Subtype then
10026          return False;
10027
10028       --  Array type. Note that we already know that this is a constrained
10029       --  array, since unconstrained arrays will fail the indefinite test.
10030
10031       elsif Is_Array_Type (Typ) then
10032
10033          --  If component type requires a transient scope, the array does too
10034
10035          if Requires_Transient_Scope (Component_Type (Typ)) then
10036             return True;
10037
10038          --  Otherwise, we only need a transient scope if the size is not
10039          --  known at compile time.
10040
10041          else
10042             return not Size_Known_At_Compile_Time (Typ);
10043          end if;
10044
10045       --  All other cases do not require a transient scope
10046
10047       else
10048          return False;
10049       end if;
10050    end Requires_Transient_Scope;
10051
10052    --------------------------
10053    -- Reset_Analyzed_Flags --
10054    --------------------------
10055
10056    procedure Reset_Analyzed_Flags (N : Node_Id) is
10057
10058       function Clear_Analyzed (N : Node_Id) return Traverse_Result;
10059       --  Function used to reset Analyzed flags in tree. Note that we do
10060       --  not reset Analyzed flags in entities, since there is no need to
10061       --  reanalyze entities, and indeed, it is wrong to do so, since it
10062       --  can result in generating auxiliary stuff more than once.
10063
10064       --------------------
10065       -- Clear_Analyzed --
10066       --------------------
10067
10068       function Clear_Analyzed (N : Node_Id) return Traverse_Result is
10069       begin
10070          if not Has_Extension (N) then
10071             Set_Analyzed (N, False);
10072          end if;
10073
10074          return OK;
10075       end Clear_Analyzed;
10076
10077       procedure Reset_Analyzed is new Traverse_Proc (Clear_Analyzed);
10078
10079    --  Start of processing for Reset_Analyzed_Flags
10080
10081    begin
10082       Reset_Analyzed (N);
10083    end Reset_Analyzed_Flags;
10084
10085    ---------------------------
10086    -- Safe_To_Capture_Value --
10087    ---------------------------
10088
10089    function Safe_To_Capture_Value
10090      (N    : Node_Id;
10091       Ent  : Entity_Id;
10092       Cond : Boolean := False) return Boolean
10093    is
10094    begin
10095       --  The only entities for which we track constant values are variables
10096       --  which are not renamings, constants, out parameters, and in out
10097       --  parameters, so check if we have this case.
10098
10099       --  Note: it may seem odd to track constant values for constants, but in
10100       --  fact this routine is used for other purposes than simply capturing
10101       --  the value. In particular, the setting of Known[_Non]_Null.
10102
10103       if (Ekind (Ent) = E_Variable and then No (Renamed_Object (Ent)))
10104             or else
10105           Ekind (Ent) = E_Constant
10106             or else
10107           Ekind (Ent) = E_Out_Parameter
10108             or else
10109           Ekind (Ent) = E_In_Out_Parameter
10110       then
10111          null;
10112
10113       --  For conditionals, we also allow loop parameters and all formals,
10114       --  including in parameters.
10115
10116       elsif Cond
10117         and then
10118           (Ekind (Ent) = E_Loop_Parameter
10119              or else
10120            Ekind (Ent) = E_In_Parameter)
10121       then
10122          null;
10123
10124       --  For all other cases, not just unsafe, but impossible to capture
10125       --  Current_Value, since the above are the only entities which have
10126       --  Current_Value fields.
10127
10128       else
10129          return False;
10130       end if;
10131
10132       --  Skip if volatile or aliased, since funny things might be going on in
10133       --  these cases which we cannot necessarily track. Also skip any variable
10134       --  for which an address clause is given, or whose address is taken. Also
10135       --  never capture value of library level variables (an attempt to do so
10136       --  can occur in the case of package elaboration code).
10137
10138       if Treat_As_Volatile (Ent)
10139         or else Is_Aliased (Ent)
10140         or else Present (Address_Clause (Ent))
10141         or else Address_Taken (Ent)
10142         or else (Is_Library_Level_Entity (Ent)
10143                    and then Ekind (Ent) = E_Variable)
10144       then
10145          return False;
10146       end if;
10147
10148       --  OK, all above conditions are met. We also require that the scope of
10149       --  the reference be the same as the scope of the entity, not counting
10150       --  packages and blocks and loops.
10151
10152       declare
10153          E_Scope : constant Entity_Id := Scope (Ent);
10154          R_Scope : Entity_Id;
10155
10156       begin
10157          R_Scope := Current_Scope;
10158          while R_Scope /= Standard_Standard loop
10159             exit when R_Scope = E_Scope;
10160
10161             if not Ekind_In (R_Scope, E_Package, E_Block, E_Loop) then
10162                return False;
10163             else
10164                R_Scope := Scope (R_Scope);
10165             end if;
10166          end loop;
10167       end;
10168
10169       --  We also require that the reference does not appear in a context
10170       --  where it is not sure to be executed (i.e. a conditional context
10171       --  or an exception handler). We skip this if Cond is True, since the
10172       --  capturing of values from conditional tests handles this ok.
10173
10174       if Cond then
10175          return True;
10176       end if;
10177
10178       declare
10179          Desc : Node_Id;
10180          P    : Node_Id;
10181
10182       begin
10183          Desc := N;
10184
10185          P := Parent (N);
10186          while Present (P) loop
10187             if         Nkind (P) = N_If_Statement
10188               or else  Nkind (P) = N_Case_Statement
10189               or else (Nkind (P) in N_Short_Circuit
10190                          and then Desc = Right_Opnd (P))
10191               or else (Nkind (P) = N_Conditional_Expression
10192                          and then Desc /= First (Expressions (P)))
10193               or else  Nkind (P) = N_Exception_Handler
10194               or else  Nkind (P) = N_Selective_Accept
10195               or else  Nkind (P) = N_Conditional_Entry_Call
10196               or else  Nkind (P) = N_Timed_Entry_Call
10197               or else  Nkind (P) = N_Asynchronous_Select
10198             then
10199                return False;
10200             else
10201                Desc := P;
10202                P    := Parent (P);
10203             end if;
10204          end loop;
10205       end;
10206
10207       --  OK, looks safe to set value
10208
10209       return True;
10210    end Safe_To_Capture_Value;
10211
10212    ---------------
10213    -- Same_Name --
10214    ---------------
10215
10216    function Same_Name (N1, N2 : Node_Id) return Boolean is
10217       K1 : constant Node_Kind := Nkind (N1);
10218       K2 : constant Node_Kind := Nkind (N2);
10219
10220    begin
10221       if (K1 = N_Identifier or else K1 = N_Defining_Identifier)
10222         and then (K2 = N_Identifier or else K2 = N_Defining_Identifier)
10223       then
10224          return Chars (N1) = Chars (N2);
10225
10226       elsif (K1 = N_Selected_Component or else K1 = N_Expanded_Name)
10227         and then (K2 = N_Selected_Component or else K2 = N_Expanded_Name)
10228       then
10229          return Same_Name (Selector_Name (N1), Selector_Name (N2))
10230            and then Same_Name (Prefix (N1), Prefix (N2));
10231
10232       else
10233          return False;
10234       end if;
10235    end Same_Name;
10236
10237    -----------------
10238    -- Same_Object --
10239    -----------------
10240
10241    function Same_Object (Node1, Node2 : Node_Id) return Boolean is
10242       N1 : constant Node_Id := Original_Node (Node1);
10243       N2 : constant Node_Id := Original_Node (Node2);
10244       --  We do the tests on original nodes, since we are most interested
10245       --  in the original source, not any expansion that got in the way.
10246
10247       K1 : constant Node_Kind := Nkind (N1);
10248       K2 : constant Node_Kind := Nkind (N2);
10249
10250    begin
10251       --  First case, both are entities with same entity
10252
10253       if K1 in N_Has_Entity
10254         and then K2 in N_Has_Entity
10255         and then Present (Entity (N1))
10256         and then Present (Entity (N2))
10257         and then (Ekind (Entity (N1)) = E_Variable
10258                     or else
10259                   Ekind (Entity (N1)) = E_Constant)
10260         and then Entity (N1) = Entity (N2)
10261       then
10262          return True;
10263
10264       --  Second case, selected component with same selector, same record
10265
10266       elsif K1 = N_Selected_Component
10267         and then K2 = N_Selected_Component
10268         and then Chars (Selector_Name (N1)) = Chars (Selector_Name (N2))
10269       then
10270          return Same_Object (Prefix (N1), Prefix (N2));
10271
10272       --  Third case, indexed component with same subscripts, same array
10273
10274       elsif K1 = N_Indexed_Component
10275         and then K2 = N_Indexed_Component
10276         and then Same_Object (Prefix (N1), Prefix (N2))
10277       then
10278          declare
10279             E1, E2 : Node_Id;
10280          begin
10281             E1 := First (Expressions (N1));
10282             E2 := First (Expressions (N2));
10283             while Present (E1) loop
10284                if not Same_Value (E1, E2) then
10285                   return False;
10286                else
10287                   Next (E1);
10288                   Next (E2);
10289                end if;
10290             end loop;
10291
10292             return True;
10293          end;
10294
10295       --  Fourth case, slice of same array with same bounds
10296
10297       elsif K1 = N_Slice
10298         and then K2 = N_Slice
10299         and then Nkind (Discrete_Range (N1)) = N_Range
10300         and then Nkind (Discrete_Range (N2)) = N_Range
10301         and then Same_Value (Low_Bound (Discrete_Range (N1)),
10302                              Low_Bound (Discrete_Range (N2)))
10303         and then Same_Value (High_Bound (Discrete_Range (N1)),
10304                              High_Bound (Discrete_Range (N2)))
10305       then
10306          return Same_Name (Prefix (N1), Prefix (N2));
10307
10308       --  All other cases, not clearly the same object
10309
10310       else
10311          return False;
10312       end if;
10313    end Same_Object;
10314
10315    ---------------
10316    -- Same_Type --
10317    ---------------
10318
10319    function Same_Type (T1, T2 : Entity_Id) return Boolean is
10320    begin
10321       if T1 = T2 then
10322          return True;
10323
10324       elsif not Is_Constrained (T1)
10325         and then not Is_Constrained (T2)
10326         and then Base_Type (T1) = Base_Type (T2)
10327       then
10328          return True;
10329
10330       --  For now don't bother with case of identical constraints, to be
10331       --  fiddled with later on perhaps (this is only used for optimization
10332       --  purposes, so it is not critical to do a best possible job)
10333
10334       else
10335          return False;
10336       end if;
10337    end Same_Type;
10338
10339    ----------------
10340    -- Same_Value --
10341    ----------------
10342
10343    function Same_Value (Node1, Node2 : Node_Id) return Boolean is
10344    begin
10345       if Compile_Time_Known_Value (Node1)
10346         and then Compile_Time_Known_Value (Node2)
10347         and then Expr_Value (Node1) = Expr_Value (Node2)
10348       then
10349          return True;
10350       elsif Same_Object (Node1, Node2) then
10351          return True;
10352       else
10353          return False;
10354       end if;
10355    end Same_Value;
10356
10357    ------------------------
10358    -- Scope_Is_Transient --
10359    ------------------------
10360
10361    function Scope_Is_Transient return Boolean is
10362    begin
10363       return Scope_Stack.Table (Scope_Stack.Last).Is_Transient;
10364    end Scope_Is_Transient;
10365
10366    ------------------
10367    -- Scope_Within --
10368    ------------------
10369
10370    function Scope_Within (Scope1, Scope2 : Entity_Id) return Boolean is
10371       Scop : Entity_Id;
10372
10373    begin
10374       Scop := Scope1;
10375       while Scop /= Standard_Standard loop
10376          Scop := Scope (Scop);
10377
10378          if Scop = Scope2 then
10379             return True;
10380          end if;
10381       end loop;
10382
10383       return False;
10384    end Scope_Within;
10385
10386    --------------------------
10387    -- Scope_Within_Or_Same --
10388    --------------------------
10389
10390    function Scope_Within_Or_Same (Scope1, Scope2 : Entity_Id) return Boolean is
10391       Scop : Entity_Id;
10392
10393    begin
10394       Scop := Scope1;
10395       while Scop /= Standard_Standard loop
10396          if Scop = Scope2 then
10397             return True;
10398          else
10399             Scop := Scope (Scop);
10400          end if;
10401       end loop;
10402
10403       return False;
10404    end Scope_Within_Or_Same;
10405
10406    --------------------
10407    -- Set_Convention --
10408    --------------------
10409
10410    procedure Set_Convention (E : Entity_Id; Val : Snames.Convention_Id) is
10411    begin
10412       Basic_Set_Convention (E, Val);
10413
10414       if Is_Type (E)
10415         and then Is_Access_Subprogram_Type (Base_Type (E))
10416         and then Has_Foreign_Convention (E)
10417       then
10418          Set_Can_Use_Internal_Rep (E, False);
10419       end if;
10420    end Set_Convention;
10421
10422    ------------------------
10423    -- Set_Current_Entity --
10424    ------------------------
10425
10426    --  The given entity is to be set as the currently visible definition
10427    --  of its associated name (i.e. the Node_Id associated with its name).
10428    --  All we have to do is to get the name from the identifier, and
10429    --  then set the associated Node_Id to point to the given entity.
10430
10431    procedure Set_Current_Entity (E : Entity_Id) is
10432    begin
10433       Set_Name_Entity_Id (Chars (E), E);
10434    end Set_Current_Entity;
10435
10436    ---------------------------
10437    -- Set_Debug_Info_Needed --
10438    ---------------------------
10439
10440    procedure Set_Debug_Info_Needed (T : Entity_Id) is
10441
10442       procedure Set_Debug_Info_Needed_If_Not_Set (E : Entity_Id);
10443       pragma Inline (Set_Debug_Info_Needed_If_Not_Set);
10444       --  Used to set debug info in a related node if not set already
10445
10446       --------------------------------------
10447       -- Set_Debug_Info_Needed_If_Not_Set --
10448       --------------------------------------
10449
10450       procedure Set_Debug_Info_Needed_If_Not_Set (E : Entity_Id) is
10451       begin
10452          if Present (E)
10453            and then not Needs_Debug_Info (E)
10454          then
10455             Set_Debug_Info_Needed (E);
10456
10457             --  For a private type, indicate that the full view also needs
10458             --  debug information.
10459
10460             if Is_Type (E)
10461               and then Is_Private_Type (E)
10462               and then Present (Full_View (E))
10463             then
10464                Set_Debug_Info_Needed (Full_View (E));
10465             end if;
10466          end if;
10467       end Set_Debug_Info_Needed_If_Not_Set;
10468
10469    --  Start of processing for Set_Debug_Info_Needed
10470
10471    begin
10472       --  Nothing to do if argument is Empty or has Debug_Info_Off set, which
10473       --  indicates that Debug_Info_Needed is never required for the entity.
10474
10475       if No (T)
10476         or else Debug_Info_Off (T)
10477       then
10478          return;
10479       end if;
10480
10481       --  Set flag in entity itself. Note that we will go through the following
10482       --  circuitry even if the flag is already set on T. That's intentional,
10483       --  it makes sure that the flag will be set in subsidiary entities.
10484
10485       Set_Needs_Debug_Info (T);
10486
10487       --  Set flag on subsidiary entities if not set already
10488
10489       if Is_Object (T) then
10490          Set_Debug_Info_Needed_If_Not_Set (Etype (T));
10491
10492       elsif Is_Type (T) then
10493          Set_Debug_Info_Needed_If_Not_Set (Etype (T));
10494
10495          if Is_Record_Type (T) then
10496             declare
10497                Ent : Entity_Id := First_Entity (T);
10498             begin
10499                while Present (Ent) loop
10500                   Set_Debug_Info_Needed_If_Not_Set (Ent);
10501                   Next_Entity (Ent);
10502                end loop;
10503             end;
10504
10505             --  For a class wide subtype, we also need debug information
10506             --  for the equivalent type.
10507
10508             if Ekind (T) = E_Class_Wide_Subtype then
10509                Set_Debug_Info_Needed_If_Not_Set (Equivalent_Type (T));
10510             end if;
10511
10512          elsif Is_Array_Type (T) then
10513             Set_Debug_Info_Needed_If_Not_Set (Component_Type (T));
10514
10515             declare
10516                Indx : Node_Id := First_Index (T);
10517             begin
10518                while Present (Indx) loop
10519                   Set_Debug_Info_Needed_If_Not_Set (Etype (Indx));
10520                   Indx := Next_Index (Indx);
10521                end loop;
10522             end;
10523
10524             if Is_Packed (T) then
10525                Set_Debug_Info_Needed_If_Not_Set (Packed_Array_Type (T));
10526             end if;
10527
10528          elsif Is_Access_Type (T) then
10529             Set_Debug_Info_Needed_If_Not_Set (Directly_Designated_Type (T));
10530
10531          elsif Is_Private_Type (T) then
10532             Set_Debug_Info_Needed_If_Not_Set (Full_View (T));
10533
10534          elsif Is_Protected_Type (T) then
10535             Set_Debug_Info_Needed_If_Not_Set (Corresponding_Record_Type (T));
10536          end if;
10537       end if;
10538    end Set_Debug_Info_Needed;
10539
10540    ---------------------------------
10541    -- Set_Entity_With_Style_Check --
10542    ---------------------------------
10543
10544    procedure Set_Entity_With_Style_Check (N : Node_Id; Val : Entity_Id) is
10545       Val_Actual : Entity_Id;
10546       Nod        : Node_Id;
10547
10548    begin
10549       Set_Entity (N, Val);
10550
10551       if Style_Check
10552         and then not Suppress_Style_Checks (Val)
10553         and then not In_Instance
10554       then
10555          if Nkind (N) = N_Identifier then
10556             Nod := N;
10557          elsif Nkind (N) = N_Expanded_Name then
10558             Nod := Selector_Name (N);
10559          else
10560             return;
10561          end if;
10562
10563          --  A special situation arises for derived operations, where we want
10564          --  to do the check against the parent (since the Sloc of the derived
10565          --  operation points to the derived type declaration itself).
10566
10567          Val_Actual := Val;
10568          while not Comes_From_Source (Val_Actual)
10569            and then Nkind (Val_Actual) in N_Entity
10570            and then (Ekind (Val_Actual) = E_Enumeration_Literal
10571                       or else Is_Subprogram (Val_Actual)
10572                       or else Is_Generic_Subprogram (Val_Actual))
10573            and then Present (Alias (Val_Actual))
10574          loop
10575             Val_Actual := Alias (Val_Actual);
10576          end loop;
10577
10578          --  Renaming declarations for generic actuals do not come from source,
10579          --  and have a different name from that of the entity they rename, so
10580          --  there is no style check to perform here.
10581
10582          if Chars (Nod) = Chars (Val_Actual) then
10583             Style.Check_Identifier (Nod, Val_Actual);
10584          end if;
10585       end if;
10586
10587       Set_Entity (N, Val);
10588    end Set_Entity_With_Style_Check;
10589
10590    ------------------------
10591    -- Set_Name_Entity_Id --
10592    ------------------------
10593
10594    procedure Set_Name_Entity_Id (Id : Name_Id; Val : Entity_Id) is
10595    begin
10596       Set_Name_Table_Info (Id, Int (Val));
10597    end Set_Name_Entity_Id;
10598
10599    ---------------------
10600    -- Set_Next_Actual --
10601    ---------------------
10602
10603    procedure Set_Next_Actual (Ass1_Id : Node_Id; Ass2_Id : Node_Id) is
10604    begin
10605       if Nkind (Parent (Ass1_Id)) = N_Parameter_Association then
10606          Set_First_Named_Actual (Parent (Ass1_Id), Ass2_Id);
10607       end if;
10608    end Set_Next_Actual;
10609
10610    ----------------------------------
10611    -- Set_Optimize_Alignment_Flags --
10612    ----------------------------------
10613
10614    procedure Set_Optimize_Alignment_Flags (E : Entity_Id) is
10615    begin
10616       if Optimize_Alignment = 'S' then
10617          Set_Optimize_Alignment_Space (E);
10618       elsif Optimize_Alignment = 'T' then
10619          Set_Optimize_Alignment_Time (E);
10620       end if;
10621    end Set_Optimize_Alignment_Flags;
10622
10623    -----------------------
10624    -- Set_Public_Status --
10625    -----------------------
10626
10627    procedure Set_Public_Status (Id : Entity_Id) is
10628       S : constant Entity_Id := Current_Scope;
10629
10630       function Within_HSS_Or_If (E : Entity_Id) return Boolean;
10631       --  Determines if E is defined within handled statement sequence or
10632       --  an if statement, returns True if so, False otherwise.
10633
10634       ----------------------
10635       -- Within_HSS_Or_If --
10636       ----------------------
10637
10638       function Within_HSS_Or_If (E : Entity_Id) return Boolean is
10639          N : Node_Id;
10640       begin
10641          N := Declaration_Node (E);
10642          loop
10643             N := Parent (N);
10644
10645             if No (N) then
10646                return False;
10647
10648             elsif Nkind_In (N, N_Handled_Sequence_Of_Statements,
10649                                N_If_Statement)
10650             then
10651                return True;
10652             end if;
10653          end loop;
10654       end Within_HSS_Or_If;
10655
10656    --  Start of processing for Set_Public_Status
10657
10658    begin
10659       --  Everything in the scope of Standard is public
10660
10661       if S = Standard_Standard then
10662          Set_Is_Public (Id);
10663
10664       --  Entity is definitely not public if enclosing scope is not public
10665
10666       elsif not Is_Public (S) then
10667          return;
10668
10669       --  An object or function declaration that occurs in a handled sequence
10670       --  of statements or within an if statement is the declaration for a
10671       --  temporary object or local subprogram generated by the expander. It
10672       --  never needs to be made public and furthermore, making it public can
10673       --  cause back end problems.
10674
10675       elsif Nkind_In (Parent (Id), N_Object_Declaration,
10676                                    N_Function_Specification)
10677         and then Within_HSS_Or_If (Id)
10678       then
10679          return;
10680
10681       --  Entities in public packages or records are public
10682
10683       elsif Ekind (S) = E_Package or Is_Record_Type (S) then
10684          Set_Is_Public (Id);
10685
10686       --  The bounds of an entry family declaration can generate object
10687       --  declarations that are visible to the back-end, e.g. in the
10688       --  the declaration of a composite type that contains tasks.
10689
10690       elsif Is_Concurrent_Type (S)
10691         and then not Has_Completion (S)
10692         and then Nkind (Parent (Id)) = N_Object_Declaration
10693       then
10694          Set_Is_Public (Id);
10695       end if;
10696    end Set_Public_Status;
10697
10698    -----------------------------
10699    -- Set_Referenced_Modified --
10700    -----------------------------
10701
10702    procedure Set_Referenced_Modified (N : Node_Id; Out_Param : Boolean) is
10703       Pref : Node_Id;
10704
10705    begin
10706       --  Deal with indexed or selected component where prefix is modified
10707
10708       if Nkind_In (N, N_Indexed_Component, N_Selected_Component) then
10709          Pref := Prefix (N);
10710
10711          --  If prefix is access type, then it is the designated object that is
10712          --  being modified, which means we have no entity to set the flag on.
10713
10714          if No (Etype (Pref)) or else Is_Access_Type (Etype (Pref)) then
10715             return;
10716
10717             --  Otherwise chase the prefix
10718
10719          else
10720             Set_Referenced_Modified (Pref, Out_Param);
10721          end if;
10722
10723       --  Otherwise see if we have an entity name (only other case to process)
10724
10725       elsif Is_Entity_Name (N) and then Present (Entity (N)) then
10726          Set_Referenced_As_LHS           (Entity (N), not Out_Param);
10727          Set_Referenced_As_Out_Parameter (Entity (N), Out_Param);
10728       end if;
10729    end Set_Referenced_Modified;
10730
10731    ----------------------------
10732    -- Set_Scope_Is_Transient --
10733    ----------------------------
10734
10735    procedure Set_Scope_Is_Transient (V : Boolean := True) is
10736    begin
10737       Scope_Stack.Table (Scope_Stack.Last).Is_Transient := V;
10738    end Set_Scope_Is_Transient;
10739
10740    -------------------
10741    -- Set_Size_Info --
10742    -------------------
10743
10744    procedure Set_Size_Info (T1, T2 : Entity_Id) is
10745    begin
10746       --  We copy Esize, but not RM_Size, since in general RM_Size is
10747       --  subtype specific and does not get inherited by all subtypes.
10748
10749       Set_Esize                     (T1, Esize                     (T2));
10750       Set_Has_Biased_Representation (T1, Has_Biased_Representation (T2));
10751
10752       if Is_Discrete_Or_Fixed_Point_Type (T1)
10753            and then
10754          Is_Discrete_Or_Fixed_Point_Type (T2)
10755       then
10756          Set_Is_Unsigned_Type       (T1, Is_Unsigned_Type          (T2));
10757       end if;
10758
10759       Set_Alignment                 (T1, Alignment                 (T2));
10760    end Set_Size_Info;
10761
10762    --------------------
10763    -- Static_Integer --
10764    --------------------
10765
10766    function Static_Integer (N : Node_Id) return Uint is
10767    begin
10768       Analyze_And_Resolve (N, Any_Integer);
10769
10770       if N = Error
10771         or else Error_Posted (N)
10772         or else Etype (N) = Any_Type
10773       then
10774          return No_Uint;
10775       end if;
10776
10777       if Is_Static_Expression (N) then
10778          if not Raises_Constraint_Error (N) then
10779             return Expr_Value (N);
10780          else
10781             return No_Uint;
10782          end if;
10783
10784       elsif Etype (N) = Any_Type then
10785          return No_Uint;
10786
10787       else
10788          Flag_Non_Static_Expr
10789            ("static integer expression required here", N);
10790          return No_Uint;
10791       end if;
10792    end Static_Integer;
10793
10794    --------------------------
10795    -- Statically_Different --
10796    --------------------------
10797
10798    function Statically_Different (E1, E2 : Node_Id) return Boolean is
10799       R1 : constant Node_Id := Get_Referenced_Object (E1);
10800       R2 : constant Node_Id := Get_Referenced_Object (E2);
10801    begin
10802       return     Is_Entity_Name (R1)
10803         and then Is_Entity_Name (R2)
10804         and then Entity (R1) /= Entity (R2)
10805         and then not Is_Formal (Entity (R1))
10806         and then not Is_Formal (Entity (R2));
10807    end Statically_Different;
10808
10809    -----------------------------
10810    -- Subprogram_Access_Level --
10811    -----------------------------
10812
10813    function Subprogram_Access_Level (Subp : Entity_Id) return Uint is
10814    begin
10815       if Present (Alias (Subp)) then
10816          return Subprogram_Access_Level (Alias (Subp));
10817       else
10818          return Scope_Depth (Enclosing_Dynamic_Scope (Subp));
10819       end if;
10820    end Subprogram_Access_Level;
10821
10822    -----------------
10823    -- Trace_Scope --
10824    -----------------
10825
10826    procedure Trace_Scope (N : Node_Id; E : Entity_Id; Msg : String) is
10827    begin
10828       if Debug_Flag_W then
10829          for J in 0 .. Scope_Stack.Last loop
10830             Write_Str ("  ");
10831          end loop;
10832
10833          Write_Str (Msg);
10834          Write_Name (Chars (E));
10835          Write_Str (" from ");
10836          Write_Location (Sloc (N));
10837          Write_Eol;
10838       end if;
10839    end Trace_Scope;
10840
10841    -----------------------
10842    -- Transfer_Entities --
10843    -----------------------
10844
10845    procedure Transfer_Entities (From : Entity_Id; To : Entity_Id) is
10846       Ent : Entity_Id := First_Entity (From);
10847
10848    begin
10849       if No (Ent) then
10850          return;
10851       end if;
10852
10853       if (Last_Entity (To)) = Empty then
10854          Set_First_Entity (To, Ent);
10855       else
10856          Set_Next_Entity (Last_Entity (To), Ent);
10857       end if;
10858
10859       Set_Last_Entity (To, Last_Entity (From));
10860
10861       while Present (Ent) loop
10862          Set_Scope (Ent, To);
10863
10864          if not Is_Public (Ent) then
10865             Set_Public_Status (Ent);
10866
10867             if Is_Public (Ent)
10868               and then Ekind (Ent) = E_Record_Subtype
10869
10870             then
10871                --  The components of the propagated Itype must be public
10872                --  as well.
10873
10874                declare
10875                   Comp : Entity_Id;
10876                begin
10877                   Comp := First_Entity (Ent);
10878                   while Present (Comp) loop
10879                      Set_Is_Public (Comp);
10880                      Next_Entity (Comp);
10881                   end loop;
10882                end;
10883             end if;
10884          end if;
10885
10886          Next_Entity (Ent);
10887       end loop;
10888
10889       Set_First_Entity (From, Empty);
10890       Set_Last_Entity (From, Empty);
10891    end Transfer_Entities;
10892
10893    -----------------------
10894    -- Type_Access_Level --
10895    -----------------------
10896
10897    function Type_Access_Level (Typ : Entity_Id) return Uint is
10898       Btyp : Entity_Id;
10899
10900    begin
10901       Btyp := Base_Type (Typ);
10902
10903       --  Ada 2005 (AI-230): For most cases of anonymous access types, we
10904       --  simply use the level where the type is declared. This is true for
10905       --  stand-alone object declarations, and for anonymous access types
10906       --  associated with components the level is the same as that of the
10907       --  enclosing composite type. However, special treatment is needed for
10908       --  the cases of access parameters, return objects of an anonymous access
10909       --  type, and, in Ada 95, access discriminants of limited types.
10910
10911       if Ekind (Btyp) in Access_Kind then
10912          if Ekind (Btyp) = E_Anonymous_Access_Type then
10913
10914             --  If the type is a nonlocal anonymous access type (such as for
10915             --  an access parameter) we treat it as being declared at the
10916             --  library level to ensure that names such as X.all'access don't
10917             --  fail static accessibility checks.
10918
10919             if not Is_Local_Anonymous_Access (Typ) then
10920                return Scope_Depth (Standard_Standard);
10921
10922             --  If this is a return object, the accessibility level is that of
10923             --  the result subtype of the enclosing function. The test here is
10924             --  little complicated, because we have to account for extended
10925             --  return statements that have been rewritten as blocks, in which
10926             --  case we have to find and the Is_Return_Object attribute of the
10927             --  itype's associated object. It would be nice to find a way to
10928             --  simplify this test, but it doesn't seem worthwhile to add a new
10929             --  flag just for purposes of this test. ???
10930
10931             elsif Ekind (Scope (Btyp)) = E_Return_Statement
10932               or else
10933                 (Is_Itype (Btyp)
10934                   and then Nkind (Associated_Node_For_Itype (Btyp)) =
10935                              N_Object_Declaration
10936                   and then Is_Return_Object
10937                              (Defining_Identifier
10938                                 (Associated_Node_For_Itype (Btyp))))
10939             then
10940                declare
10941                   Scop : Entity_Id;
10942
10943                begin
10944                   Scop := Scope (Scope (Btyp));
10945                   while Present (Scop) loop
10946                      exit when Ekind (Scop) = E_Function;
10947                      Scop := Scope (Scop);
10948                   end loop;
10949
10950                   --  Treat the return object's type as having the level of the
10951                   --  function's result subtype (as per RM05-6.5(5.3/2)).
10952
10953                   return Type_Access_Level (Etype (Scop));
10954                end;
10955             end if;
10956          end if;
10957
10958          Btyp := Root_Type (Btyp);
10959
10960          --  The accessibility level of anonymous access types associated with
10961          --  discriminants is that of the current instance of the type, and
10962          --  that's deeper than the type itself (AARM 3.10.2 (12.3.21)).
10963
10964          --  AI-402: access discriminants have accessibility based on the
10965          --  object rather than the type in Ada 2005, so the above paragraph
10966          --  doesn't apply.
10967
10968          --  ??? Needs completion with rules from AI-416
10969
10970          if Ada_Version <= Ada_95
10971            and then Ekind (Typ) = E_Anonymous_Access_Type
10972            and then Present (Associated_Node_For_Itype (Typ))
10973            and then Nkind (Associated_Node_For_Itype (Typ)) =
10974                                                  N_Discriminant_Specification
10975          then
10976             return Scope_Depth (Enclosing_Dynamic_Scope (Btyp)) + 1;
10977          end if;
10978       end if;
10979
10980       return Scope_Depth (Enclosing_Dynamic_Scope (Btyp));
10981    end Type_Access_Level;
10982
10983    --------------------
10984    -- Ultimate_Alias --
10985    --------------------
10986    --  To do: add occurrences calling this new subprogram
10987
10988    function Ultimate_Alias (Prim : Entity_Id) return Entity_Id is
10989       E : Entity_Id := Prim;
10990
10991    begin
10992       while Present (Alias (E)) loop
10993          E := Alias (E);
10994       end loop;
10995
10996       return E;
10997    end Ultimate_Alias;
10998
10999    --------------------------
11000    -- Unit_Declaration_Node --
11001    --------------------------
11002
11003    function Unit_Declaration_Node (Unit_Id : Entity_Id) return Node_Id is
11004       N : Node_Id := Parent (Unit_Id);
11005
11006    begin
11007       --  Predefined operators do not have a full function declaration
11008
11009       if Ekind (Unit_Id) = E_Operator then
11010          return N;
11011       end if;
11012
11013       --  Isn't there some better way to express the following ???
11014
11015       while Nkind (N) /= N_Abstract_Subprogram_Declaration
11016         and then Nkind (N) /= N_Formal_Package_Declaration
11017         and then Nkind (N) /= N_Function_Instantiation
11018         and then Nkind (N) /= N_Generic_Package_Declaration
11019         and then Nkind (N) /= N_Generic_Subprogram_Declaration
11020         and then Nkind (N) /= N_Package_Declaration
11021         and then Nkind (N) /= N_Package_Body
11022         and then Nkind (N) /= N_Package_Instantiation
11023         and then Nkind (N) /= N_Package_Renaming_Declaration
11024         and then Nkind (N) /= N_Procedure_Instantiation
11025         and then Nkind (N) /= N_Protected_Body
11026         and then Nkind (N) /= N_Subprogram_Declaration
11027         and then Nkind (N) /= N_Subprogram_Body
11028         and then Nkind (N) /= N_Subprogram_Body_Stub
11029         and then Nkind (N) /= N_Subprogram_Renaming_Declaration
11030         and then Nkind (N) /= N_Task_Body
11031         and then Nkind (N) /= N_Task_Type_Declaration
11032         and then Nkind (N) not in N_Formal_Subprogram_Declaration
11033         and then Nkind (N) not in N_Generic_Renaming_Declaration
11034       loop
11035          N := Parent (N);
11036          pragma Assert (Present (N));
11037       end loop;
11038
11039       return N;
11040    end Unit_Declaration_Node;
11041
11042    ------------------------------
11043    -- Universal_Interpretation --
11044    ------------------------------
11045
11046    function Universal_Interpretation (Opnd : Node_Id) return Entity_Id is
11047       Index : Interp_Index;
11048       It    : Interp;
11049
11050    begin
11051       --  The argument may be a formal parameter of an operator or subprogram
11052       --  with multiple interpretations, or else an expression for an actual.
11053
11054       if Nkind (Opnd) = N_Defining_Identifier
11055         or else not Is_Overloaded (Opnd)
11056       then
11057          if Etype (Opnd) = Universal_Integer
11058            or else Etype (Opnd) = Universal_Real
11059          then
11060             return Etype (Opnd);
11061          else
11062             return Empty;
11063          end if;
11064
11065       else
11066          Get_First_Interp (Opnd, Index, It);
11067          while Present (It.Typ) loop
11068             if It.Typ = Universal_Integer
11069               or else It.Typ = Universal_Real
11070             then
11071                return It.Typ;
11072             end if;
11073
11074             Get_Next_Interp (Index, It);
11075          end loop;
11076
11077          return Empty;
11078       end if;
11079    end Universal_Interpretation;
11080
11081    ---------------
11082    -- Unqualify --
11083    ---------------
11084
11085    function Unqualify (Expr : Node_Id) return Node_Id is
11086    begin
11087       --  Recurse to handle unlikely case of multiple levels of qualification
11088
11089       if Nkind (Expr) = N_Qualified_Expression then
11090          return Unqualify (Expression (Expr));
11091
11092       --  Normal case, not a qualified expression
11093
11094       else
11095          return Expr;
11096       end if;
11097    end Unqualify;
11098
11099    ----------------------
11100    -- Within_Init_Proc --
11101    ----------------------
11102
11103    function Within_Init_Proc return Boolean is
11104       S : Entity_Id;
11105
11106    begin
11107       S := Current_Scope;
11108       while not Is_Overloadable (S) loop
11109          if S = Standard_Standard then
11110             return False;
11111          else
11112             S := Scope (S);
11113          end if;
11114       end loop;
11115
11116       return Is_Init_Proc (S);
11117    end Within_Init_Proc;
11118
11119    ----------------
11120    -- Wrong_Type --
11121    ----------------
11122
11123    procedure Wrong_Type (Expr : Node_Id; Expected_Type : Entity_Id) is
11124       Found_Type : constant Entity_Id := First_Subtype (Etype (Expr));
11125       Expec_Type : constant Entity_Id := First_Subtype (Expected_Type);
11126
11127       function Has_One_Matching_Field return Boolean;
11128       --  Determines if Expec_Type is a record type with a single component or
11129       --  discriminant whose type matches the found type or is one dimensional
11130       --  array whose component type matches the found type.
11131
11132       ----------------------------
11133       -- Has_One_Matching_Field --
11134       ----------------------------
11135
11136       function Has_One_Matching_Field return Boolean is
11137          E : Entity_Id;
11138
11139       begin
11140          if Is_Array_Type (Expec_Type)
11141            and then Number_Dimensions (Expec_Type) = 1
11142            and then
11143              Covers (Etype (Component_Type (Expec_Type)), Found_Type)
11144          then
11145             return True;
11146
11147          elsif not Is_Record_Type (Expec_Type) then
11148             return False;
11149
11150          else
11151             E := First_Entity (Expec_Type);
11152             loop
11153                if No (E) then
11154                   return False;
11155
11156                elsif (Ekind (E) /= E_Discriminant
11157                        and then Ekind (E) /= E_Component)
11158                  or else (Chars (E) = Name_uTag
11159                            or else Chars (E) = Name_uParent)
11160                then
11161                   Next_Entity (E);
11162
11163                else
11164                   exit;
11165                end if;
11166             end loop;
11167
11168             if not Covers (Etype (E), Found_Type) then
11169                return False;
11170
11171             elsif Present (Next_Entity (E)) then
11172                return False;
11173
11174             else
11175                return True;
11176             end if;
11177          end if;
11178       end Has_One_Matching_Field;
11179
11180    --  Start of processing for Wrong_Type
11181
11182    begin
11183       --  Don't output message if either type is Any_Type, or if a message
11184       --  has already been posted for this node. We need to do the latter
11185       --  check explicitly (it is ordinarily done in Errout), because we
11186       --  are using ! to force the output of the error messages.
11187
11188       if Expec_Type = Any_Type
11189         or else Found_Type = Any_Type
11190         or else Error_Posted (Expr)
11191       then
11192          return;
11193
11194       --  In  an instance, there is an ongoing problem with completion of
11195       --  type derived from private types. Their structure is what Gigi
11196       --  expects, but the  Etype is the parent type rather than the
11197       --  derived private type itself. Do not flag error in this case. The
11198       --  private completion is an entity without a parent, like an Itype.
11199       --  Similarly, full and partial views may be incorrect in the instance.
11200       --  There is no simple way to insure that it is consistent ???
11201
11202       elsif In_Instance then
11203          if Etype (Etype (Expr)) = Etype (Expected_Type)
11204            and then
11205              (Has_Private_Declaration (Expected_Type)
11206                or else Has_Private_Declaration (Etype (Expr)))
11207            and then No (Parent (Expected_Type))
11208          then
11209             return;
11210          end if;
11211       end if;
11212
11213       --  An interesting special check. If the expression is parenthesized
11214       --  and its type corresponds to the type of the sole component of the
11215       --  expected record type, or to the component type of the expected one
11216       --  dimensional array type, then assume we have a bad aggregate attempt.
11217
11218       if Nkind (Expr) in N_Subexpr
11219         and then Paren_Count (Expr) /= 0
11220         and then Has_One_Matching_Field
11221       then
11222          Error_Msg_N ("positional aggregate cannot have one component", Expr);
11223
11224       --  Another special check, if we are looking for a pool-specific access
11225       --  type and we found an E_Access_Attribute_Type, then we have the case
11226       --  of an Access attribute being used in a context which needs a pool-
11227       --  specific type, which is never allowed. The one extra check we make
11228       --  is that the expected designated type covers the Found_Type.
11229
11230       elsif Is_Access_Type (Expec_Type)
11231         and then Ekind (Found_Type) = E_Access_Attribute_Type
11232         and then Ekind (Base_Type (Expec_Type)) /= E_General_Access_Type
11233         and then Ekind (Base_Type (Expec_Type)) /= E_Anonymous_Access_Type
11234         and then Covers
11235           (Designated_Type (Expec_Type), Designated_Type (Found_Type))
11236       then
11237          Error_Msg_N ("result must be general access type!", Expr);
11238          Error_Msg_NE ("add ALL to }!", Expr, Expec_Type);
11239
11240       --  Another special check, if the expected type is an integer type,
11241       --  but the expression is of type System.Address, and the parent is
11242       --  an addition or subtraction operation whose left operand is the
11243       --  expression in question and whose right operand is of an integral
11244       --  type, then this is an attempt at address arithmetic, so give
11245       --  appropriate message.
11246
11247       elsif Is_Integer_Type (Expec_Type)
11248         and then Is_RTE (Found_Type, RE_Address)
11249         and then (Nkind (Parent (Expr)) = N_Op_Add
11250                     or else
11251                   Nkind (Parent (Expr)) = N_Op_Subtract)
11252         and then Expr = Left_Opnd (Parent (Expr))
11253         and then Is_Integer_Type (Etype (Right_Opnd (Parent (Expr))))
11254       then
11255          Error_Msg_N
11256            ("address arithmetic not predefined in package System",
11257             Parent (Expr));
11258          Error_Msg_N
11259            ("\possible missing with/use of System.Storage_Elements",
11260             Parent (Expr));
11261          return;
11262
11263       --  If the expected type is an anonymous access type, as for access
11264       --  parameters and discriminants, the error is on the designated types.
11265
11266       elsif Ekind (Expec_Type) = E_Anonymous_Access_Type then
11267          if Comes_From_Source (Expec_Type) then
11268             Error_Msg_NE ("expected}!", Expr, Expec_Type);
11269          else
11270             Error_Msg_NE
11271               ("expected an access type with designated}",
11272                  Expr, Designated_Type (Expec_Type));
11273          end if;
11274
11275          if Is_Access_Type (Found_Type)
11276            and then not Comes_From_Source (Found_Type)
11277          then
11278             Error_Msg_NE
11279               ("\\found an access type with designated}!",
11280                 Expr, Designated_Type (Found_Type));
11281          else
11282             if From_With_Type (Found_Type) then
11283                Error_Msg_NE ("\\found incomplete}!", Expr, Found_Type);
11284                Error_Msg_Qual_Level := 99;
11285                Error_Msg_NE ("\\missing `WITH &;", Expr, Scope (Found_Type));
11286                Error_Msg_Qual_Level := 0;
11287             else
11288                Error_Msg_NE ("found}!", Expr, Found_Type);
11289             end if;
11290          end if;
11291
11292       --  Normal case of one type found, some other type expected
11293
11294       else
11295          --  If the names of the two types are the same, see if some number
11296          --  of levels of qualification will help. Don't try more than three
11297          --  levels, and if we get to standard, it's no use (and probably
11298          --  represents an error in the compiler) Also do not bother with
11299          --  internal scope names.
11300
11301          declare
11302             Expec_Scope : Entity_Id;
11303             Found_Scope : Entity_Id;
11304
11305          begin
11306             Expec_Scope := Expec_Type;
11307             Found_Scope := Found_Type;
11308
11309             for Levels in Int range 0 .. 3 loop
11310                if Chars (Expec_Scope) /= Chars (Found_Scope) then
11311                   Error_Msg_Qual_Level := Levels;
11312                   exit;
11313                end if;
11314
11315                Expec_Scope := Scope (Expec_Scope);
11316                Found_Scope := Scope (Found_Scope);
11317
11318                exit when Expec_Scope = Standard_Standard
11319                  or else Found_Scope = Standard_Standard
11320                  or else not Comes_From_Source (Expec_Scope)
11321                  or else not Comes_From_Source (Found_Scope);
11322             end loop;
11323          end;
11324
11325          if Is_Record_Type (Expec_Type)
11326            and then Present (Corresponding_Remote_Type (Expec_Type))
11327          then
11328             Error_Msg_NE ("expected}!", Expr,
11329                           Corresponding_Remote_Type (Expec_Type));
11330          else
11331             Error_Msg_NE ("expected}!", Expr, Expec_Type);
11332          end if;
11333
11334          if Is_Entity_Name (Expr)
11335            and then Is_Package_Or_Generic_Package (Entity (Expr))
11336          then
11337             Error_Msg_N ("\\found package name!", Expr);
11338
11339          elsif Is_Entity_Name (Expr)
11340            and then
11341              (Ekind (Entity (Expr)) = E_Procedure
11342                 or else
11343               Ekind (Entity (Expr)) = E_Generic_Procedure)
11344          then
11345             if Ekind (Expec_Type) = E_Access_Subprogram_Type then
11346                Error_Msg_N
11347                  ("found procedure name, possibly missing Access attribute!",
11348                    Expr);
11349             else
11350                Error_Msg_N
11351                  ("\\found procedure name instead of function!", Expr);
11352             end if;
11353
11354          elsif Nkind (Expr) = N_Function_Call
11355            and then Ekind (Expec_Type) = E_Access_Subprogram_Type
11356            and then Etype (Designated_Type (Expec_Type)) = Etype (Expr)
11357            and then No (Parameter_Associations (Expr))
11358          then
11359             Error_Msg_N
11360               ("found function name, possibly missing Access attribute!",
11361                Expr);
11362
11363          --  Catch common error: a prefix or infix operator which is not
11364          --  directly visible because the type isn't.
11365
11366          elsif Nkind (Expr) in N_Op
11367             and then Is_Overloaded (Expr)
11368             and then not Is_Immediately_Visible (Expec_Type)
11369             and then not Is_Potentially_Use_Visible (Expec_Type)
11370             and then not In_Use (Expec_Type)
11371             and then Has_Compatible_Type (Right_Opnd (Expr), Expec_Type)
11372          then
11373             Error_Msg_N
11374               ("operator of the type is not directly visible!", Expr);
11375
11376          elsif Ekind (Found_Type) = E_Void
11377            and then Present (Parent (Found_Type))
11378            and then Nkind (Parent (Found_Type)) = N_Full_Type_Declaration
11379          then
11380             Error_Msg_NE ("\\found premature usage of}!", Expr, Found_Type);
11381
11382          else
11383             Error_Msg_NE ("\\found}!", Expr, Found_Type);
11384          end if;
11385
11386          --  A special check for cases like M1 and M2 = 0 where M1 and M2 are
11387          --  of the same modular type, and (M1 and M2) = 0 was intended.
11388
11389          if Expec_Type = Standard_Boolean
11390            and then Is_Modular_Integer_Type (Found_Type)
11391            and then Nkind_In (Parent (Expr), N_Op_And, N_Op_Or, N_Op_Xor)
11392            and then Nkind (Right_Opnd (Parent (Expr))) in N_Op_Compare
11393          then
11394             declare
11395                Op : constant Node_Id := Right_Opnd (Parent (Expr));
11396                L  : constant Node_Id := Left_Opnd (Op);
11397                R  : constant Node_Id := Right_Opnd (Op);
11398             begin
11399                --  The case for the message is when the left operand of the
11400                --  comparison is the same modular type, or when it is an
11401                --  integer literal (or other universal integer expression),
11402                --  which would have been typed as the modular type if the
11403                --  parens had been there.
11404
11405                if (Etype (L) = Found_Type
11406                      or else
11407                    Etype (L) = Universal_Integer)
11408                  and then Is_Integer_Type (Etype (R))
11409                then
11410                   Error_Msg_N
11411                     ("\\possible missing parens for modular operation", Expr);
11412                end if;
11413             end;
11414          end if;
11415
11416          --  Reset error message qualification indication
11417
11418          Error_Msg_Qual_Level := 0;
11419       end if;
11420    end Wrong_Type;
11421
11422 end Sem_Util;