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) 1992-2011, 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 Restrict; use Restrict;
  44 with Rtsfind;  use Rtsfind;
  45 with Sem;      use Sem;
  46 with Sem_Aux;  use Sem_Aux;
  47 with Sem_Attr; use Sem_Attr;
  48 with Sem_Ch8;  use Sem_Ch8;
  49 with Sem_Disp; use Sem_Disp;
  50 with Sem_Eval; use Sem_Eval;
  51 with Sem_Res;  use Sem_Res;
  52 with Sem_Type; use Sem_Type;
  53 with Sinfo;    use Sinfo;
  54 with Sinput;   use Sinput;
  55 with Stand;    use Stand;
  56 with Style;
  57 with Stringt;  use Stringt;
  58 with Table;
  59 with Targparm; use Targparm;
  60 with Tbuild;   use Tbuild;
  61 with Ttypes;   use Ttypes;
  62 with Uname;    use Uname;
  63
  64 with GNAT.HTable; use GNAT.HTable;
  65
  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_Threshold : 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 threshold 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    -- Order Dependence (AI05-0144) --
  99    ----------------------------------
 100
 101    --  Each actual in a call is entered into the table below. A flag indicates
 102    --  whether the corresponding formal is OUT or IN OUT. Each top-level call
 103    --  (procedure call, condition, assignment) examines all the actuals for a
 104    --  possible order dependence. The table is reset after each such check.
 105    --  The actuals to be checked in a call to Check_Order_Dependence are at
 106    --  positions 1 .. Last.
 107
 108    type Actual_Name is record
 109       Act         : Node_Id;
 110       Is_Writable : Boolean;
 111    end record;
 112
 113    package Actuals_In_Call is new Table.Table (
 114       Table_Component_Type => Actual_Name,
 115       Table_Index_Type     => Int,
 116       Table_Low_Bound      => 0,
 117       Table_Initial        => 10,
 118       Table_Increment      => 100,
 119       Table_Name           => "Actuals");
 120
 121    -----------------------
 122    -- Local Subprograms --
 123    -----------------------
 124
 125    function Build_Component_Subtype
 126      (C   : List_Id;
 127       Loc : Source_Ptr;
 128       T   : Entity_Id) return Node_Id;
 129    --  This function builds the subtype for Build_Actual_Subtype_Of_Component
 130    --  and Build_Discriminal_Subtype_Of_Component. C is a list of constraints,
 131    --  Loc is the source location, T is the original subtype.
 132
 133    function Is_Fully_Initialized_Variant (Typ : Entity_Id) return Boolean;
 134    --  Subsidiary to Is_Fully_Initialized_Type. For an unconstrained type
 135    --  with discriminants whose default values are static, examine only the
 136    --  components in the selected variant to determine whether all of them
 137    --  have a default.
 138
 139    function Has_Null_Extension (T : Entity_Id) return Boolean;
 140    --  T is a derived tagged type. Check whether the type extension is null.
 141    --  If the parent type is fully initialized, T can be treated as such.
 142
 143    ------------------------------
 144    --  Abstract_Interface_List --
 145    ------------------------------
 146
 147    function Abstract_Interface_List (Typ : Entity_Id) return List_Id is
 148       Nod : Node_Id;
 149
 150    begin
 151       if Is_Concurrent_Type (Typ) then
 152
 153          --  If we are dealing with a synchronized subtype, go to the base
 154          --  type, whose declaration has the interface list.
 155
 156          --  Shouldn't this be Declaration_Node???
 157
 158          Nod := Parent (Base_Type (Typ));
 159
 160          if Nkind (Nod) = N_Full_Type_Declaration then
 161             return Empty_List;
 162          end if;
 163
 164       elsif Ekind (Typ) = E_Record_Type_With_Private then
 165          if Nkind (Parent (Typ)) = N_Full_Type_Declaration then
 166             Nod := Type_Definition (Parent (Typ));
 167
 168          elsif Nkind (Parent (Typ)) = N_Private_Type_Declaration then
 169             if Present (Full_View (Typ))
 170               and then Nkind (Parent (Full_View (Typ)))
 171                          = N_Full_Type_Declaration
 172             then
 173                Nod := Type_Definition (Parent (Full_View (Typ)));
 174
 175             --  If the full-view is not available we cannot do anything else
 176             --  here (the source has errors).
 177
 178             else
 179                return Empty_List;
 180             end if;
 181
 182          --  Support for generic formals with interfaces is still missing ???
 183
 184          elsif Nkind (Parent (Typ)) = N_Formal_Type_Declaration then
 185             return Empty_List;
 186
 187          else
 188             pragma Assert
 189               (Nkind (Parent (Typ)) = N_Private_Extension_Declaration);
 190             Nod := Parent (Typ);
 191          end if;
 192
 193       elsif Ekind (Typ) = E_Record_Subtype then
 194          Nod := Type_Definition (Parent (Etype (Typ)));
 195
 196       elsif Ekind (Typ) = E_Record_Subtype_With_Private then
 197
 198          --  Recurse, because parent may still be a private extension. Also
 199          --  note that the full view of the subtype or the full view of its
 200          --  base type may (both) be unavailable.
 201
 202          return Abstract_Interface_List (Etype (Typ));
 203
 204       else pragma Assert ((Ekind (Typ)) = E_Record_Type);
 205          if Nkind (Parent (Typ)) = N_Formal_Type_Declaration then
 206             Nod := Formal_Type_Definition (Parent (Typ));
 207          else
 208             Nod := Type_Definition (Parent (Typ));
 209          end if;
 210       end if;
 211
 212       return Interface_List (Nod);
 213    end Abstract_Interface_List;
 214
 215    --------------------------------
 216    -- Add_Access_Type_To_Process --
 217    --------------------------------
 218
 219    procedure Add_Access_Type_To_Process (E : Entity_Id; A : Entity_Id) is
 220       L : Elist_Id;
 221
 222    begin
 223       Ensure_Freeze_Node (E);
 224       L := Access_Types_To_Process (Freeze_Node (E));
 225
 226       if No (L) then
 227          L := New_Elmt_List;
 228          Set_Access_Types_To_Process (Freeze_Node (E), L);
 229       end if;
 230
 231       Append_Elmt (A, L);
 232    end Add_Access_Type_To_Process;
 233
 234    ----------------------------
 235    -- Add_Global_Declaration --
 236    ----------------------------
 237
 238    procedure Add_Global_Declaration (N : Node_Id) is
 239       Aux_Node : constant Node_Id := Aux_Decls_Node (Cunit (Current_Sem_Unit));
 240
 241    begin
 242       if No (Declarations (Aux_Node)) then
 243          Set_Declarations (Aux_Node, New_List);
 244       end if;
 245
 246       Append_To (Declarations (Aux_Node), N);
 247       Analyze (N);
 248    end Add_Global_Declaration;
 249
 250    -----------------
 251    -- Addressable --
 252    -----------------
 253
 254    --  For now, just 8/16/32/64. but analyze later if AAMP is special???
 255
 256    function Addressable (V : Uint) return Boolean is
 257    begin
 258       return V = Uint_8  or else
 259              V = Uint_16 or else
 260              V = Uint_32 or else
 261              V = Uint_64;
 262    end Addressable;
 263
 264    function Addressable (V : Int) return Boolean is
 265    begin
 266       return V = 8  or else
 267              V = 16 or else
 268              V = 32 or else
 269              V = 64;
 270    end Addressable;
 271
 272    -----------------------
 273    -- Alignment_In_Bits --
 274    -----------------------
 275
 276    function Alignment_In_Bits (E : Entity_Id) return Uint is
 277    begin
 278       return Alignment (E) * System_Storage_Unit;
 279    end Alignment_In_Bits;
 280
 281    -----------------------------------------
 282    -- Apply_Compile_Time_Constraint_Error --
 283    -----------------------------------------
 284
 285    procedure Apply_Compile_Time_Constraint_Error
 286      (N      : Node_Id;
 287       Msg    : String;
 288       Reason : RT_Exception_Code;
 289       Ent    : Entity_Id  := Empty;
 290       Typ    : Entity_Id  := Empty;
 291       Loc    : Source_Ptr := No_Location;
 292       Rep    : Boolean    := True;
 293       Warn   : Boolean    := False)
 294    is
 295       Stat   : constant Boolean := Is_Static_Expression (N);
 296       R_Stat : constant Node_Id :=
 297                  Make_Raise_Constraint_Error (Sloc (N), Reason => Reason);
 298       Rtyp   : Entity_Id;
 299
 300    begin
 301       if No (Typ) then
 302          Rtyp := Etype (N);
 303       else
 304          Rtyp := Typ;
 305       end if;
 306
 307       Discard_Node
 308         (Compile_Time_Constraint_Error (N, Msg, Ent, Loc, Warn => Warn));
 309
 310       if not Rep then
 311          return;
 312       end if;
 313
 314       --  Now we replace the node by an N_Raise_Constraint_Error node
 315       --  This does not need reanalyzing, so set it as analyzed now.
 316
 317       Rewrite (N, R_Stat);
 318       Set_Analyzed (N, True);
 319
 320       Set_Etype (N, Rtyp);
 321       Set_Raises_Constraint_Error (N);
 322
 323       --  Now deal with possible local raise handling
 324
 325       Possible_Local_Raise (N, Standard_Constraint_Error);
 326
 327       --  If the original expression was marked as static, the result is
 328       --  still marked as static, but the Raises_Constraint_Error flag is
 329       --  always set so that further static evaluation is not attempted.
 330
 331       if Stat then
 332          Set_Is_Static_Expression (N);
 333       end if;
 334    end Apply_Compile_Time_Constraint_Error;
 335
 336    --------------------------------
 337    -- Bad_Predicated_Subtype_Use --
 338    --------------------------------
 339
 340    procedure Bad_Predicated_Subtype_Use
 341      (Msg : String;
 342       N   : Node_Id;
 343       Typ : Entity_Id)
 344    is
 345    begin
 346       if Has_Predicates (Typ) then
 347          if Is_Generic_Actual_Type (Typ) then
 348             Error_Msg_FE (Msg & '?', N, Typ);
 349             Error_Msg_F ("\Program_Error will be raised at run time?", N);
 350             Insert_Action (N,
 351               Make_Raise_Program_Error (Sloc (N),
 352                 Reason => PE_Bad_Predicated_Generic_Type));
 353
 354          else
 355             Error_Msg_FE (Msg, N, Typ);
 356          end if;
 357       end if;
 358    end Bad_Predicated_Subtype_Use;
 359
 360    --------------------------
 361    -- Build_Actual_Subtype --
 362    --------------------------
 363
 364    function Build_Actual_Subtype
 365      (T : Entity_Id;
 366       N : Node_Or_Entity_Id) return Node_Id
 367    is
 368       Loc : Source_Ptr;
 369       --  Normally Sloc (N), but may point to corresponding body in some cases
 370
 371       Constraints : List_Id;
 372       Decl        : Node_Id;
 373       Discr       : Entity_Id;
 374       Hi          : Node_Id;
 375       Lo          : Node_Id;
 376       Subt        : Entity_Id;
 377       Disc_Type   : Entity_Id;
 378       Obj         : Node_Id;
 379
 380    begin
 381       Loc := Sloc (N);
 382
 383       if Nkind (N) = N_Defining_Identifier then
 384          Obj := New_Reference_To (N, Loc);
 385
 386          --  If this is a formal parameter of a subprogram declaration, and
 387          --  we are compiling the body, we want the declaration for the
 388          --  actual subtype to carry the source position of the body, to
 389          --  prevent anomalies in gdb when stepping through the code.
 390
 391          if Is_Formal (N) then
 392             declare
 393                Decl : constant Node_Id := Unit_Declaration_Node (Scope (N));
 394             begin
 395                if Nkind (Decl) = N_Subprogram_Declaration
 396                  and then Present (Corresponding_Body (Decl))
 397                then
 398                   Loc := Sloc (Corresponding_Body (Decl));
 399                end if;
 400             end;
 401          end if;
 402
 403       else
 404          Obj := N;
 405       end if;
 406
 407       if Is_Array_Type (T) then
 408          Constraints := New_List;
 409          for J in 1 .. Number_Dimensions (T) loop
 410
 411             --  Build an array subtype declaration with the nominal subtype and
 412             --  the bounds of the actual. Add the declaration in front of the
 413             --  local declarations for the subprogram, for analysis before any
 414             --  reference to the formal in the body.
 415
 416             Lo :=
 417               Make_Attribute_Reference (Loc,
 418                 Prefix         =>
 419                   Duplicate_Subexpr_No_Checks (Obj, Name_Req => True),
 420                 Attribute_Name => Name_First,
 421                 Expressions    => New_List (
 422                   Make_Integer_Literal (Loc, J)));
 423
 424             Hi :=
 425               Make_Attribute_Reference (Loc,
 426                 Prefix         =>
 427                   Duplicate_Subexpr_No_Checks (Obj, Name_Req => True),
 428                 Attribute_Name => Name_Last,
 429                 Expressions    => New_List (
 430                   Make_Integer_Literal (Loc, J)));
 431
 432             Append (Make_Range (Loc, Lo, Hi), Constraints);
 433          end loop;
 434
 435       --  If the type has unknown discriminants there is no constrained
 436       --  subtype to build. This is never called for a formal or for a
 437       --  lhs, so returning the type is ok ???
 438
 439       elsif Has_Unknown_Discriminants (T) then
 440          return T;
 441
 442       else
 443          Constraints := New_List;
 444
 445          --  Type T is a generic derived type, inherit the discriminants from
 446          --  the parent type.
 447
 448          if Is_Private_Type (T)
 449            and then No (Full_View (T))
 450
 451             --  T was flagged as an error if it was declared as a formal
 452             --  derived type with known discriminants. In this case there
 453             --  is no need to look at the parent type since T already carries
 454             --  its own discriminants.
 455
 456            and then not Error_Posted (T)
 457          then
 458             Disc_Type := Etype (Base_Type (T));
 459          else
 460             Disc_Type := T;
 461          end if;
 462
 463          Discr := First_Discriminant (Disc_Type);
 464          while Present (Discr) loop
 465             Append_To (Constraints,
 466               Make_Selected_Component (Loc,
 467                 Prefix =>
 468                   Duplicate_Subexpr_No_Checks (Obj),
 469                 Selector_Name => New_Occurrence_Of (Discr, Loc)));
 470             Next_Discriminant (Discr);
 471          end loop;
 472       end if;
 473
 474       Subt := Make_Temporary (Loc, 'S', Related_Node => N);
 475       Set_Is_Internal (Subt);
 476
 477       Decl :=
 478         Make_Subtype_Declaration (Loc,
 479           Defining_Identifier => Subt,
 480           Subtype_Indication =>
 481             Make_Subtype_Indication (Loc,
 482               Subtype_Mark => New_Reference_To (T,  Loc),
 483               Constraint  =>
 484                 Make_Index_Or_Discriminant_Constraint (Loc,
 485                   Constraints => Constraints)));
 486
 487       Mark_Rewrite_Insertion (Decl);
 488       return Decl;
 489    end Build_Actual_Subtype;
 490
 491    ---------------------------------------
 492    -- Build_Actual_Subtype_Of_Component --
 493    ---------------------------------------
 494
 495    function Build_Actual_Subtype_Of_Component
 496      (T : Entity_Id;
 497       N : Node_Id) return Node_Id
 498    is
 499       Loc       : constant Source_Ptr := Sloc (N);
 500       P         : constant Node_Id    := Prefix (N);
 501       D         : Elmt_Id;
 502       Id        : Node_Id;
 503       Indx_Type : Entity_Id;
 504
 505       Deaccessed_T : Entity_Id;
 506       --  This is either a copy of T, or if T is an access type, then it is
 507       --  the directly designated type of this access type.
 508
 509       function Build_Actual_Array_Constraint return List_Id;
 510       --  If one or more of the bounds of the component depends on
 511       --  discriminants, build  actual constraint using the discriminants
 512       --  of the prefix.
 513
 514       function Build_Actual_Record_Constraint return List_Id;
 515       --  Similar to previous one, for discriminated components constrained
 516       --  by the discriminant of the enclosing object.
 517
 518       -----------------------------------
 519       -- Build_Actual_Array_Constraint --
 520       -----------------------------------
 521
 522       function Build_Actual_Array_Constraint return List_Id is
 523          Constraints : constant List_Id := New_List;
 524          Indx        : Node_Id;
 525          Hi          : Node_Id;
 526          Lo          : Node_Id;
 527          Old_Hi      : Node_Id;
 528          Old_Lo      : Node_Id;
 529
 530       begin
 531          Indx := First_Index (Deaccessed_T);
 532          while Present (Indx) loop
 533             Old_Lo := Type_Low_Bound  (Etype (Indx));
 534             Old_Hi := Type_High_Bound (Etype (Indx));
 535
 536             if Denotes_Discriminant (Old_Lo) then
 537                Lo :=
 538                  Make_Selected_Component (Loc,
 539                    Prefix => New_Copy_Tree (P),
 540                    Selector_Name => New_Occurrence_Of (Entity (Old_Lo), Loc));
 541
 542             else
 543                Lo := New_Copy_Tree (Old_Lo);
 544
 545                --  The new bound will be reanalyzed in the enclosing
 546                --  declaration. For literal bounds that come from a type
 547                --  declaration, the type of the context must be imposed, so
 548                --  insure that analysis will take place. For non-universal
 549                --  types this is not strictly necessary.
 550
 551                Set_Analyzed (Lo, False);
 552             end if;
 553
 554             if Denotes_Discriminant (Old_Hi) then
 555                Hi :=
 556                  Make_Selected_Component (Loc,
 557                    Prefix => New_Copy_Tree (P),
 558                    Selector_Name => New_Occurrence_Of (Entity (Old_Hi), Loc));
 559
 560             else
 561                Hi := New_Copy_Tree (Old_Hi);
 562                Set_Analyzed (Hi, False);
 563             end if;
 564
 565             Append (Make_Range (Loc, Lo, Hi), Constraints);
 566             Next_Index (Indx);
 567          end loop;
 568
 569          return Constraints;
 570       end Build_Actual_Array_Constraint;
 571
 572       ------------------------------------
 573       -- Build_Actual_Record_Constraint --
 574       ------------------------------------
 575
 576       function Build_Actual_Record_Constraint return List_Id is
 577          Constraints : constant List_Id := New_List;
 578          D           : Elmt_Id;
 579          D_Val       : Node_Id;
 580
 581       begin
 582          D := First_Elmt (Discriminant_Constraint (Deaccessed_T));
 583          while Present (D) loop
 584             if Denotes_Discriminant (Node (D)) then
 585                D_Val :=  Make_Selected_Component (Loc,
 586                  Prefix => New_Copy_Tree (P),
 587                 Selector_Name => New_Occurrence_Of (Entity (Node (D)), Loc));
 588
 589             else
 590                D_Val := New_Copy_Tree (Node (D));
 591             end if;
 592
 593             Append (D_Val, Constraints);
 594             Next_Elmt (D);
 595          end loop;
 596
 597          return Constraints;
 598       end Build_Actual_Record_Constraint;
 599
 600    --  Start of processing for Build_Actual_Subtype_Of_Component
 601
 602    begin
 603       --  Why the test for Spec_Expression mode here???
 604
 605       if In_Spec_Expression then
 606          return Empty;
 607
 608       --  More comments for the rest of this body would be good ???
 609
 610       elsif Nkind (N) = N_Explicit_Dereference then
 611          if Is_Composite_Type (T)
 612            and then not Is_Constrained (T)
 613            and then not (Is_Class_Wide_Type (T)
 614                           and then Is_Constrained (Root_Type (T)))
 615            and then not Has_Unknown_Discriminants (T)
 616          then
 617             --  If the type of the dereference is already constrained, it is an
 618             --  actual subtype.
 619
 620             if Is_Array_Type (Etype (N))
 621               and then Is_Constrained (Etype (N))
 622             then
 623                return Empty;
 624             else
 625                Remove_Side_Effects (P);
 626                return Build_Actual_Subtype (T, N);
 627             end if;
 628          else
 629             return Empty;
 630          end if;
 631       end if;
 632
 633       if Ekind (T) = E_Access_Subtype then
 634          Deaccessed_T := Designated_Type (T);
 635       else
 636          Deaccessed_T := T;
 637       end if;
 638
 639       if Ekind (Deaccessed_T) = E_Array_Subtype then
 640          Id := First_Index (Deaccessed_T);
 641          while Present (Id) loop
 642             Indx_Type := Underlying_Type (Etype (Id));
 643
 644             if Denotes_Discriminant (Type_Low_Bound  (Indx_Type))
 645                  or else
 646                Denotes_Discriminant (Type_High_Bound (Indx_Type))
 647             then
 648                Remove_Side_Effects (P);
 649                return
 650                  Build_Component_Subtype
 651                    (Build_Actual_Array_Constraint, Loc, Base_Type (T));
 652             end if;
 653
 654             Next_Index (Id);
 655          end loop;
 656
 657       elsif Is_Composite_Type (Deaccessed_T)
 658         and then Has_Discriminants (Deaccessed_T)
 659         and then not Has_Unknown_Discriminants (Deaccessed_T)
 660       then
 661          D := First_Elmt (Discriminant_Constraint (Deaccessed_T));
 662          while Present (D) loop
 663             if Denotes_Discriminant (Node (D)) then
 664                Remove_Side_Effects (P);
 665                return
 666                  Build_Component_Subtype (
 667                    Build_Actual_Record_Constraint, Loc, Base_Type (T));
 668             end if;
 669
 670             Next_Elmt (D);
 671          end loop;
 672       end if;
 673
 674       --  If none of the above, the actual and nominal subtypes are the same
 675
 676       return Empty;
 677    end Build_Actual_Subtype_Of_Component;
 678
 679    -----------------------------
 680    -- Build_Component_Subtype --
 681    -----------------------------
 682
 683    function Build_Component_Subtype
 684      (C   : List_Id;
 685       Loc : Source_Ptr;
 686       T   : Entity_Id) return Node_Id
 687    is
 688       Subt : Entity_Id;
 689       Decl : Node_Id;
 690
 691    begin
 692       --  Unchecked_Union components do not require component subtypes
 693
 694       if Is_Unchecked_Union (T) then
 695          return Empty;
 696       end if;
 697
 698       Subt := Make_Temporary (Loc, 'S');
 699       Set_Is_Internal (Subt);
 700
 701       Decl :=
 702         Make_Subtype_Declaration (Loc,
 703           Defining_Identifier => Subt,
 704           Subtype_Indication =>
 705             Make_Subtype_Indication (Loc,
 706               Subtype_Mark => New_Reference_To (Base_Type (T),  Loc),
 707               Constraint  =>
 708                 Make_Index_Or_Discriminant_Constraint (Loc,
 709                   Constraints => C)));
 710
 711       Mark_Rewrite_Insertion (Decl);
 712       return Decl;
 713    end Build_Component_Subtype;
 714
 715    ---------------------------
 716    -- Build_Default_Subtype --
 717    ---------------------------
 718
 719    function Build_Default_Subtype
 720      (T : Entity_Id;
 721       N : Node_Id) return Entity_Id
 722    is
 723       Loc  : constant Source_Ptr := Sloc (N);
 724       Disc : Entity_Id;
 725
 726    begin
 727       if not Has_Discriminants (T) or else Is_Constrained (T) then
 728          return T;
 729       end if;
 730
 731       Disc := First_Discriminant (T);
 732
 733       if No (Discriminant_Default_Value (Disc)) then
 734          return T;
 735       end if;
 736
 737       declare
 738          Act         : constant Entity_Id := Make_Temporary (Loc, 'S');
 739          Constraints : constant List_Id := New_List;
 740          Decl        : Node_Id;
 741
 742       begin
 743          while Present (Disc) loop
 744             Append_To (Constraints,
 745               New_Copy_Tree (Discriminant_Default_Value (Disc)));
 746             Next_Discriminant (Disc);
 747          end loop;
 748
 749          Decl :=
 750            Make_Subtype_Declaration (Loc,
 751              Defining_Identifier => Act,
 752              Subtype_Indication =>
 753                Make_Subtype_Indication (Loc,
 754                  Subtype_Mark => New_Occurrence_Of (T, Loc),
 755                  Constraint =>
 756                    Make_Index_Or_Discriminant_Constraint (Loc,
 757                      Constraints => Constraints)));
 758
 759          Insert_Action (N, Decl);
 760          Analyze (Decl);
 761          return Act;
 762       end;
 763    end Build_Default_Subtype;
 764
 765    --------------------------------------------
 766    -- Build_Discriminal_Subtype_Of_Component --
 767    --------------------------------------------
 768
 769    function Build_Discriminal_Subtype_Of_Component
 770      (T : Entity_Id) return Node_Id
 771    is
 772       Loc : constant Source_Ptr := Sloc (T);
 773       D   : Elmt_Id;
 774       Id  : Node_Id;
 775
 776       function Build_Discriminal_Array_Constraint return List_Id;
 777       --  If one or more of the bounds of the component depends on
 778       --  discriminants, build  actual constraint using the discriminants
 779       --  of the prefix.
 780
 781       function Build_Discriminal_Record_Constraint return List_Id;
 782       --  Similar to previous one, for discriminated components constrained
 783       --  by the discriminant of the enclosing object.
 784
 785       ----------------------------------------
 786       -- Build_Discriminal_Array_Constraint --
 787       ----------------------------------------
 788
 789       function Build_Discriminal_Array_Constraint return List_Id is
 790          Constraints : constant List_Id := New_List;
 791          Indx        : Node_Id;
 792          Hi          : Node_Id;
 793          Lo          : Node_Id;
 794          Old_Hi      : Node_Id;
 795          Old_Lo      : Node_Id;
 796
 797       begin
 798          Indx := First_Index (T);
 799          while Present (Indx) loop
 800             Old_Lo := Type_Low_Bound  (Etype (Indx));
 801             Old_Hi := Type_High_Bound (Etype (Indx));
 802
 803             if Denotes_Discriminant (Old_Lo) then
 804                Lo := New_Occurrence_Of (Discriminal (Entity (Old_Lo)), Loc);
 805
 806             else
 807                Lo := New_Copy_Tree (Old_Lo);
 808             end if;
 809
 810             if Denotes_Discriminant (Old_Hi) then
 811                Hi := New_Occurrence_Of (Discriminal (Entity (Old_Hi)), Loc);
 812
 813             else
 814                Hi := New_Copy_Tree (Old_Hi);
 815             end if;
 816
 817             Append (Make_Range (Loc, Lo, Hi), Constraints);
 818             Next_Index (Indx);
 819          end loop;
 820
 821          return Constraints;
 822       end Build_Discriminal_Array_Constraint;
 823
 824       -----------------------------------------
 825       -- Build_Discriminal_Record_Constraint --
 826       -----------------------------------------
 827
 828       function Build_Discriminal_Record_Constraint return List_Id is
 829          Constraints : constant List_Id := New_List;
 830          D           : Elmt_Id;
 831          D_Val       : Node_Id;
 832
 833       begin
 834          D := First_Elmt (Discriminant_Constraint (T));
 835          while Present (D) loop
 836             if Denotes_Discriminant (Node (D)) then
 837                D_Val :=
 838                  New_Occurrence_Of (Discriminal (Entity (Node (D))), Loc);
 839
 840             else
 841                D_Val := New_Copy_Tree (Node (D));
 842             end if;
 843
 844             Append (D_Val, Constraints);
 845             Next_Elmt (D);
 846          end loop;
 847
 848          return Constraints;
 849       end Build_Discriminal_Record_Constraint;
 850
 851    --  Start of processing for Build_Discriminal_Subtype_Of_Component
 852
 853    begin
 854       if Ekind (T) = E_Array_Subtype then
 855          Id := First_Index (T);
 856          while Present (Id) loop
 857             if Denotes_Discriminant (Type_Low_Bound  (Etype (Id))) or else
 858                Denotes_Discriminant (Type_High_Bound (Etype (Id)))
 859             then
 860                return Build_Component_Subtype
 861                  (Build_Discriminal_Array_Constraint, Loc, T);
 862             end if;
 863
 864             Next_Index (Id);
 865          end loop;
 866
 867       elsif Ekind (T) = E_Record_Subtype
 868         and then Has_Discriminants (T)
 869         and then not Has_Unknown_Discriminants (T)
 870       then
 871          D := First_Elmt (Discriminant_Constraint (T));
 872          while Present (D) loop
 873             if Denotes_Discriminant (Node (D)) then
 874                return Build_Component_Subtype
 875                  (Build_Discriminal_Record_Constraint, Loc, T);
 876             end if;
 877
 878             Next_Elmt (D);
 879          end loop;
 880       end if;
 881
 882       --  If none of the above, the actual and nominal subtypes are the same
 883
 884       return Empty;
 885    end Build_Discriminal_Subtype_Of_Component;
 886
 887    ------------------------------
 888    -- Build_Elaboration_Entity --
 889    ------------------------------
 890
 891    procedure Build_Elaboration_Entity (N : Node_Id; Spec_Id : Entity_Id) is
 892       Loc      : constant Source_Ptr := Sloc (N);
 893       Decl     : Node_Id;
 894       Elab_Ent : Entity_Id;
 895
 896       procedure Set_Package_Name (Ent : Entity_Id);
 897       --  Given an entity, sets the fully qualified name of the entity in
 898       --  Name_Buffer, with components separated by double underscores. This
 899       --  is a recursive routine that climbs the scope chain to Standard.
 900
 901       ----------------------
 902       -- Set_Package_Name --
 903       ----------------------
 904
 905       procedure Set_Package_Name (Ent : Entity_Id) is
 906       begin
 907          if Scope (Ent) /= Standard_Standard then
 908             Set_Package_Name (Scope (Ent));
 909
 910             declare
 911                Nam : constant String := Get_Name_String (Chars (Ent));
 912             begin
 913                Name_Buffer (Name_Len + 1) := '_';
 914                Name_Buffer (Name_Len + 2) := '_';
 915                Name_Buffer (Name_Len + 3 .. Name_Len + Nam'Length + 2) := Nam;
 916                Name_Len := Name_Len + Nam'Length + 2;
 917             end;
 918
 919          else
 920             Get_Name_String (Chars (Ent));
 921          end if;
 922       end Set_Package_Name;
 923
 924    --  Start of processing for Build_Elaboration_Entity
 925
 926    begin
 927       --  Ignore if already constructed
 928
 929       if Present (Elaboration_Entity (Spec_Id)) then
 930          return;
 931       end if;
 932
 933       --  Construct name of elaboration entity as xxx_E, where xxx is the unit
 934       --  name with dots replaced by double underscore. We have to manually
 935       --  construct this name, since it will be elaborated in the outer scope,
 936       --  and thus will not have the unit name automatically prepended.
 937
 938       Set_Package_Name (Spec_Id);
 939
 940       --  Append _E
 941
 942       Name_Buffer (Name_Len + 1) := '_';
 943       Name_Buffer (Name_Len + 2) := 'E';
 944       Name_Len := Name_Len + 2;
 945
 946       --  Create elaboration flag
 947
 948       Elab_Ent :=
 949         Make_Defining_Identifier (Loc, Chars => Name_Find);
 950       Set_Elaboration_Entity (Spec_Id, Elab_Ent);
 951
 952       Decl :=
 953          Make_Object_Declaration (Loc,
 954            Defining_Identifier => Elab_Ent,
 955            Object_Definition   =>
 956              New_Occurrence_Of (Standard_Boolean, Loc),
 957            Expression          =>
 958              New_Occurrence_Of (Standard_False, Loc));
 959
 960       Push_Scope (Standard_Standard);
 961       Add_Global_Declaration (Decl);
 962       Pop_Scope;
 963
 964       --  Reset True_Constant indication, since we will indeed assign a value
 965       --  to the variable in the binder main. We also kill the Current_Value
 966       --  and Last_Assignment fields for the same reason.
 967
 968       Set_Is_True_Constant (Elab_Ent, False);
 969       Set_Current_Value    (Elab_Ent, Empty);
 970       Set_Last_Assignment  (Elab_Ent, Empty);
 971
 972       --  We do not want any further qualification of the name (if we did
 973       --  not do this, we would pick up the name of the generic package
 974       --  in the case of a library level generic instantiation).
 975
 976       Set_Has_Qualified_Name       (Elab_Ent);
 977       Set_Has_Fully_Qualified_Name (Elab_Ent);
 978    end Build_Elaboration_Entity;
 979
 980    -----------------------------------
 981    -- Cannot_Raise_Constraint_Error --
 982    -----------------------------------
 983
 984    function Cannot_Raise_Constraint_Error (Expr : Node_Id) return Boolean is
 985    begin
 986       if Compile_Time_Known_Value (Expr) then
 987          return True;
 988
 989       elsif Do_Range_Check (Expr) then
 990          return False;
 991
 992       elsif Raises_Constraint_Error (Expr) then
 993          return False;
 994
 995       else
 996          case Nkind (Expr) is
 997             when N_Identifier =>
 998                return True;
 999
1000             when N_Expanded_Name =>
1001                return True;
1002
1003             when N_Selected_Component =>
1004                return not Do_Discriminant_Check (Expr);
1005
1006             when N_Attribute_Reference =>
1007                if Do_Overflow_Check (Expr) then
1008                   return False;
1009
1010                elsif No (Expressions (Expr)) then
1011                   return True;
1012
1013                else
1014                   declare
1015                      N : Node_Id;
1016
1017                   begin
1018                      N := First (Expressions (Expr));
1019                      while Present (N) loop
1020                         if Cannot_Raise_Constraint_Error (N) then
1021                            Next (N);
1022                         else
1023                            return False;
1024                         end if;
1025                      end loop;
1026
1027                      return True;
1028                   end;
1029                end if;
1030
1031             when N_Type_Conversion =>
1032                if Do_Overflow_Check (Expr)
1033                  or else Do_Length_Check (Expr)
1034                  or else Do_Tag_Check (Expr)
1035                then
1036                   return False;
1037                else
1038                   return
1039                     Cannot_Raise_Constraint_Error (Expression (Expr));
1040                end if;
1041
1042             when N_Unchecked_Type_Conversion =>
1043                return Cannot_Raise_Constraint_Error (Expression (Expr));
1044
1045             when N_Unary_Op =>
1046                if Do_Overflow_Check (Expr) then
1047                   return False;
1048                else
1049                   return
1050                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
1051                end if;
1052
1053             when N_Op_Divide |
1054                  N_Op_Mod    |
1055                  N_Op_Rem
1056             =>
1057                if Do_Division_Check (Expr)
1058                  or else Do_Overflow_Check (Expr)
1059                then
1060                   return False;
1061                else
1062                   return
1063                     Cannot_Raise_Constraint_Error (Left_Opnd (Expr))
1064                       and then
1065                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
1066                end if;
1067
1068             when N_Op_Add                    |
1069                  N_Op_And                    |
1070                  N_Op_Concat                 |
1071                  N_Op_Eq                     |
1072                  N_Op_Expon                  |
1073                  N_Op_Ge                     |
1074                  N_Op_Gt                     |
1075                  N_Op_Le                     |
1076                  N_Op_Lt                     |
1077                  N_Op_Multiply               |
1078                  N_Op_Ne                     |
1079                  N_Op_Or                     |
1080                  N_Op_Rotate_Left            |
1081                  N_Op_Rotate_Right           |
1082                  N_Op_Shift_Left             |
1083                  N_Op_Shift_Right            |
1084                  N_Op_Shift_Right_Arithmetic |
1085                  N_Op_Subtract               |
1086                  N_Op_Xor
1087             =>
1088                if Do_Overflow_Check (Expr) then
1089                   return False;
1090                else
1091                   return
1092                     Cannot_Raise_Constraint_Error (Left_Opnd (Expr))
1093                       and then
1094                     Cannot_Raise_Constraint_Error (Right_Opnd (Expr));
1095                end if;
1096
1097             when others =>
1098                return False;
1099          end case;
1100       end if;
1101    end Cannot_Raise_Constraint_Error;
1102
1103    -----------------------------------------
1104    -- Check_Dynamically_Tagged_Expression --
1105    -----------------------------------------
1106
1107    procedure Check_Dynamically_Tagged_Expression
1108      (Expr        : Node_Id;
1109       Typ         : Entity_Id;
1110       Related_Nod : Node_Id)
1111    is
1112    begin
1113       pragma Assert (Is_Tagged_Type (Typ));
1114
1115       --  In order to avoid spurious errors when analyzing the expanded code,
1116       --  this check is done only for nodes that come from source and for
1117       --  actuals of generic instantiations.
1118
1119       if (Comes_From_Source (Related_Nod)
1120            or else In_Generic_Actual (Expr))
1121         and then (Is_Class_Wide_Type (Etype (Expr))
1122                    or else Is_Dynamically_Tagged (Expr))
1123         and then Is_Tagged_Type (Typ)
1124         and then not Is_Class_Wide_Type (Typ)
1125       then
1126          Error_Msg_N ("dynamically tagged expression not allowed!", Expr);
1127       end if;
1128    end Check_Dynamically_Tagged_Expression;
1129
1130    --------------------------
1131    -- Check_Fully_Declared --
1132    --------------------------
1133
1134    procedure Check_Fully_Declared (T : Entity_Id; N : Node_Id) is
1135    begin
1136       if Ekind (T) = E_Incomplete_Type then
1137
1138          --  Ada 2005 (AI-50217): If the type is available through a limited
1139          --  with_clause, verify that its full view has been analyzed.
1140
1141          if From_With_Type (T)
1142            and then Present (Non_Limited_View (T))
1143            and then Ekind (Non_Limited_View (T)) /= E_Incomplete_Type
1144          then
1145             --  The non-limited view is fully declared
1146             null;
1147
1148          else
1149             Error_Msg_NE
1150               ("premature usage of incomplete}", N, First_Subtype (T));
1151          end if;
1152
1153       --  Need comments for these tests ???
1154
1155       elsif Has_Private_Component (T)
1156         and then not Is_Generic_Type (Root_Type (T))
1157         and then not In_Spec_Expression
1158       then
1159          --  Special case: if T is the anonymous type created for a single
1160          --  task or protected object, use the name of the source object.
1161
1162          if Is_Concurrent_Type (T)
1163            and then not Comes_From_Source (T)
1164            and then Nkind (N) = N_Object_Declaration
1165          then
1166             Error_Msg_NE ("type of& has incomplete component", N,
1167               Defining_Identifier (N));
1168
1169          else
1170             Error_Msg_NE
1171               ("premature usage of incomplete}", N, First_Subtype (T));
1172          end if;
1173       end if;
1174    end Check_Fully_Declared;
1175
1176    -------------------------
1177    -- Check_Nested_Access --
1178    -------------------------
1179
1180    procedure Check_Nested_Access (Ent : Entity_Id) is
1181       Scop         : constant Entity_Id := Current_Scope;
1182       Current_Subp : Entity_Id;
1183       Enclosing    : Entity_Id;
1184
1185    begin
1186       --  Currently only enabled for VM back-ends for efficiency, should we
1187       --  enable it more systematically ???
1188
1189       --  Check for Is_Imported needs commenting below ???
1190
1191       if VM_Target /= No_VM
1192         and then (Ekind (Ent) = E_Variable
1193                     or else
1194                   Ekind (Ent) = E_Constant
1195                     or else
1196                   Ekind (Ent) = E_Loop_Parameter)
1197         and then Scope (Ent) /= Empty
1198         and then not Is_Library_Level_Entity (Ent)
1199         and then not Is_Imported (Ent)
1200       then
1201          if Is_Subprogram (Scop)
1202            or else Is_Generic_Subprogram (Scop)
1203            or else Is_Entry (Scop)
1204          then
1205             Current_Subp := Scop;
1206          else
1207             Current_Subp := Current_Subprogram;
1208          end if;
1209
1210          Enclosing := Enclosing_Subprogram (Ent);
1211
1212          if Enclosing /= Empty
1213            and then Enclosing /= Current_Subp
1214          then
1215             Set_Has_Up_Level_Access (Ent, True);
1216          end if;
1217       end if;
1218    end Check_Nested_Access;
1219
1220    ----------------------------
1221    -- Check_Order_Dependence --
1222    ----------------------------
1223
1224    procedure Check_Order_Dependence is
1225       Act1 : Node_Id;
1226       Act2 : Node_Id;
1227
1228    begin
1229       if Ada_Version < Ada_2012 then
1230          return;
1231       end if;
1232
1233       --  Ada 2012 AI04-0144-2: Dangerous order dependence. Actuals in nested
1234       --  calls within a construct have been collected. If one of them is
1235       --  writable and overlaps with another one, evaluation of the enclosing
1236       --  construct is nondeterministic. This is illegal in Ada 2012, but is
1237       --  treated as a warning for now.
1238
1239       for J in 1 .. Actuals_In_Call.Last loop
1240          if Actuals_In_Call.Table (J).Is_Writable then
1241             Act1 := Actuals_In_Call.Table (J).Act;
1242
1243             if Nkind (Act1) = N_Attribute_Reference then
1244                Act1 := Prefix (Act1);
1245             end if;
1246
1247             for K in 1 .. Actuals_In_Call.Last loop
1248                if K /= J then
1249                   Act2 := Actuals_In_Call.Table (K).Act;
1250
1251                   if Nkind (Act2) = N_Attribute_Reference then
1252                      Act2 := Prefix (Act2);
1253                   end if;
1254
1255                   if Actuals_In_Call.Table (K).Is_Writable
1256                     and then K < J
1257                   then
1258                      --  Already checked
1259
1260                      null;
1261
1262                   elsif Denotes_Same_Object (Act1, Act2)
1263                     and then Parent (Act1) /= Parent (Act2)
1264                   then
1265                      Error_Msg_N
1266                        ("result may differ if evaluated "
1267                         & "after other actual in expression?", Act1);
1268                   end if;
1269                end if;
1270             end loop;
1271          end if;
1272       end loop;
1273
1274       --  Remove checked actuals from table
1275
1276       Actuals_In_Call.Set_Last (0);
1277    end Check_Order_Dependence;
1278
1279    ------------------------------------------
1280    -- Check_Potentially_Blocking_Operation --
1281    ------------------------------------------
1282
1283    procedure Check_Potentially_Blocking_Operation (N : Node_Id) is
1284       S : Entity_Id;
1285
1286    begin
1287       --  N is one of the potentially blocking operations listed in 9.5.1(8).
1288       --  When pragma Detect_Blocking is active, the run time will raise
1289       --  Program_Error. Here we only issue a warning, since we generally
1290       --  support the use of potentially blocking operations in the absence
1291       --  of the pragma.
1292
1293       --  Indirect blocking through a subprogram call cannot be diagnosed
1294       --  statically without interprocedural analysis, so we do not attempt
1295       --  to do it here.
1296
1297       S := Scope (Current_Scope);
1298       while Present (S) and then S /= Standard_Standard loop
1299          if Is_Protected_Type (S) then
1300             Error_Msg_N
1301               ("potentially blocking operation in protected operation?", N);
1302             return;
1303          end if;
1304
1305          S := Scope (S);
1306       end loop;
1307    end Check_Potentially_Blocking_Operation;
1308
1309    ------------------------------
1310    -- Check_Unprotected_Access --
1311    ------------------------------
1312
1313    procedure Check_Unprotected_Access
1314      (Context : Node_Id;
1315       Expr    : Node_Id)
1316    is
1317       Cont_Encl_Typ : Entity_Id;
1318       Pref_Encl_Typ : Entity_Id;
1319
1320       function Enclosing_Protected_Type (Obj : Node_Id) return Entity_Id;
1321       --  Check whether Obj is a private component of a protected object.
1322       --  Return the protected type where the component resides, Empty
1323       --  otherwise.
1324
1325       function Is_Public_Operation return Boolean;
1326       --  Verify that the enclosing operation is callable from outside the
1327       --  protected object, to minimize false positives.
1328
1329       ------------------------------
1330       -- Enclosing_Protected_Type --
1331       ------------------------------
1332
1333       function Enclosing_Protected_Type (Obj : Node_Id) return Entity_Id is
1334       begin
1335          if Is_Entity_Name (Obj) then
1336             declare
1337                Ent : Entity_Id := Entity (Obj);
1338
1339             begin
1340                --  The object can be a renaming of a private component, use
1341                --  the original record component.
1342
1343                if Is_Prival (Ent) then
1344                   Ent := Prival_Link (Ent);
1345                end if;
1346
1347                if Is_Protected_Type (Scope (Ent)) then
1348                   return Scope (Ent);
1349                end if;
1350             end;
1351          end if;
1352
1353          --  For indexed and selected components, recursively check the prefix
1354
1355          if Nkind_In (Obj, N_Indexed_Component, N_Selected_Component) then
1356             return Enclosing_Protected_Type (Prefix (Obj));
1357
1358          --  The object does not denote a protected component
1359
1360          else
1361             return Empty;
1362          end if;
1363       end Enclosing_Protected_Type;
1364
1365       -------------------------
1366       -- Is_Public_Operation --
1367       -------------------------
1368
1369       function Is_Public_Operation return Boolean is
1370          S : Entity_Id;
1371          E : Entity_Id;
1372
1373       begin
1374          S := Current_Scope;
1375          while Present (S)
1376            and then S /= Pref_Encl_Typ
1377          loop
1378             if Scope (S) = Pref_Encl_Typ then
1379                E := First_Entity (Pref_Encl_Typ);
1380                while Present (E)
1381                  and then E /= First_Private_Entity (Pref_Encl_Typ)
1382                loop
1383                   if E = S then
1384                      return True;
1385                   end if;
1386                   Next_Entity (E);
1387                end loop;
1388             end if;
1389
1390             S := Scope (S);
1391          end loop;
1392
1393          return False;
1394       end Is_Public_Operation;
1395
1396    --  Start of processing for Check_Unprotected_Access
1397
1398    begin
1399       if Nkind (Expr) = N_Attribute_Reference
1400         and then Attribute_Name (Expr) = Name_Unchecked_Access
1401       then
1402          Cont_Encl_Typ := Enclosing_Protected_Type (Context);
1403          Pref_Encl_Typ := Enclosing_Protected_Type (Prefix (Expr));
1404
1405          --  Check whether we are trying to export a protected component to a
1406          --  context with an equal or lower access level.
1407
1408          if Present (Pref_Encl_Typ)
1409            and then No (Cont_Encl_Typ)
1410            and then Is_Public_Operation
1411            and then Scope_Depth (Pref_Encl_Typ) >=
1412                       Object_Access_Level (Context)
1413          then
1414             Error_Msg_N
1415               ("?possible unprotected access to protected data", Expr);
1416          end if;
1417       end if;
1418    end Check_Unprotected_Access;
1419
1420    ---------------
1421    -- Check_VMS --
1422    ---------------
1423
1424    procedure Check_VMS (Construct : Node_Id) is
1425    begin
1426       if not OpenVMS_On_Target then
1427          Error_Msg_N
1428            ("this construct is allowed only in Open'V'M'S", Construct);
1429       end if;
1430    end Check_VMS;
1431
1432    ------------------------
1433    -- Collect_Interfaces --
1434    ------------------------
1435
1436    procedure Collect_Interfaces
1437      (T               : Entity_Id;
1438       Ifaces_List     : out Elist_Id;
1439       Exclude_Parents : Boolean := False;
1440       Use_Full_View   : Boolean := True)
1441    is
1442       procedure Collect (Typ : Entity_Id);
1443       --  Subsidiary subprogram used to traverse the whole list
1444       --  of directly and indirectly implemented interfaces
1445
1446       -------------
1447       -- Collect --
1448       -------------
1449
1450       procedure Collect (Typ : Entity_Id) is
1451          Ancestor   : Entity_Id;
1452          Full_T     : Entity_Id;
1453          Id         : Node_Id;
1454          Iface      : Entity_Id;
1455
1456       begin
1457          Full_T := Typ;
1458
1459          --  Handle private types
1460
1461          if Use_Full_View
1462            and then Is_Private_Type (Typ)
1463            and then Present (Full_View (Typ))
1464          then
1465             Full_T := Full_View (Typ);
1466          end if;
1467
1468          --  Include the ancestor if we are generating the whole list of
1469          --  abstract interfaces.
1470
1471          if Etype (Full_T) /= Typ
1472
1473             --  Protect the frontend against wrong sources. For example:
1474
1475             --    package P is
1476             --      type A is tagged null record;
1477             --      type B is new A with private;
1478             --      type C is new A with private;
1479             --    private
1480             --      type B is new C with null record;
1481             --      type C is new B with null record;
1482             --    end P;
1483
1484            and then Etype (Full_T) /= T
1485          then
1486             Ancestor := Etype (Full_T);
1487             Collect (Ancestor);
1488
1489             if Is_Interface (Ancestor)
1490               and then not Exclude_Parents
1491             then
1492                Append_Unique_Elmt (Ancestor, Ifaces_List);
1493             end if;
1494          end if;
1495
1496          --  Traverse the graph of ancestor interfaces
1497
1498          if Is_Non_Empty_List (Abstract_Interface_List (Full_T)) then
1499             Id := First (Abstract_Interface_List (Full_T));
1500             while Present (Id) loop
1501                Iface := Etype (Id);
1502
1503                --  Protect against wrong uses. For example:
1504                --    type I is interface;
1505                --    type O is tagged null record;
1506                --    type Wrong is new I and O with null record; -- ERROR
1507
1508                if Is_Interface (Iface) then
1509                   if Exclude_Parents
1510                     and then Etype (T) /= T
1511                     and then Interface_Present_In_Ancestor (Etype (T), Iface)
1512                   then
1513                      null;
1514                   else
1515                      Collect (Iface);
1516                      Append_Unique_Elmt (Iface, Ifaces_List);
1517                   end if;
1518                end if;
1519
1520                Next (Id);
1521             end loop;
1522          end if;
1523       end Collect;
1524
1525    --  Start of processing for Collect_Interfaces
1526
1527    begin
1528       pragma Assert (Is_Tagged_Type (T) or else Is_Concurrent_Type (T));
1529       Ifaces_List := New_Elmt_List;
1530       Collect (T);
1531    end Collect_Interfaces;
1532
1533    ----------------------------------
1534    -- Collect_Interface_Components --
1535    ----------------------------------
1536
1537    procedure Collect_Interface_Components
1538      (Tagged_Type     : Entity_Id;
1539       Components_List : out Elist_Id)
1540    is
1541       procedure Collect (Typ : Entity_Id);
1542       --  Subsidiary subprogram used to climb to the parents
1543
1544       -------------
1545       -- Collect --
1546       -------------
1547
1548       procedure Collect (Typ : Entity_Id) is
1549          Tag_Comp   : Entity_Id;
1550          Parent_Typ : Entity_Id;
1551
1552       begin
1553          --  Handle private types
1554
1555          if Present (Full_View (Etype (Typ))) then
1556             Parent_Typ := Full_View (Etype (Typ));
1557          else
1558             Parent_Typ := Etype (Typ);
1559          end if;
1560
1561          if Parent_Typ /= Typ
1562
1563             --  Protect the frontend against wrong sources. For example:
1564
1565             --    package P is
1566             --      type A is tagged null record;
1567             --      type B is new A with private;
1568             --      type C is new A with private;
1569             --    private
1570             --      type B is new C with null record;
1571             --      type C is new B with null record;
1572             --    end P;
1573
1574            and then Parent_Typ /= Tagged_Type
1575          then
1576             Collect (Parent_Typ);
1577          end if;
1578
1579          --  Collect the components containing tags of secondary dispatch
1580          --  tables.
1581
1582          Tag_Comp := Next_Tag_Component (First_Tag_Component (Typ));
1583          while Present (Tag_Comp) loop
1584             pragma Assert (Present (Related_Type (Tag_Comp)));
1585             Append_Elmt (Tag_Comp, Components_List);
1586
1587             Tag_Comp := Next_Tag_Component (Tag_Comp);
1588          end loop;
1589       end Collect;
1590
1591    --  Start of processing for Collect_Interface_Components
1592
1593    begin
1594       pragma Assert (Ekind (Tagged_Type) = E_Record_Type
1595         and then Is_Tagged_Type (Tagged_Type));
1596
1597       Components_List := New_Elmt_List;
1598       Collect (Tagged_Type);
1599    end Collect_Interface_Components;
1600
1601    -----------------------------
1602    -- Collect_Interfaces_Info --
1603    -----------------------------
1604
1605    procedure Collect_Interfaces_Info
1606      (T               : Entity_Id;
1607       Ifaces_List     : out Elist_Id;
1608       Components_List : out Elist_Id;
1609       Tags_List       : out Elist_Id)
1610    is
1611       Comps_List : Elist_Id;
1612       Comp_Elmt  : Elmt_Id;
1613       Comp_Iface : Entity_Id;
1614       Iface_Elmt : Elmt_Id;
1615       Iface      : Entity_Id;
1616
1617       function Search_Tag (Iface : Entity_Id) return Entity_Id;
1618       --  Search for the secondary tag associated with the interface type
1619       --  Iface that is implemented by T.
1620
1621       ----------------
1622       -- Search_Tag --
1623       ----------------
1624
1625       function Search_Tag (Iface : Entity_Id) return Entity_Id is
1626          ADT : Elmt_Id;
1627       begin
1628          if not Is_CPP_Class (T) then
1629             ADT := Next_Elmt (Next_Elmt (First_Elmt (Access_Disp_Table (T))));
1630          else
1631             ADT := Next_Elmt (First_Elmt (Access_Disp_Table (T)));
1632          end if;
1633
1634          while Present (ADT)
1635             and then Is_Tag (Node (ADT))
1636             and then Related_Type (Node (ADT)) /= Iface
1637          loop
1638             --  Skip secondary dispatch table referencing thunks to user
1639             --  defined primitives covered by this interface.
1640
1641             pragma Assert (Has_Suffix (Node (ADT), 'P'));
1642             Next_Elmt (ADT);
1643
1644             --  Skip secondary dispatch tables of Ada types
1645
1646             if not Is_CPP_Class (T) then
1647
1648                --  Skip secondary dispatch table referencing thunks to
1649                --  predefined primitives.
1650
1651                pragma Assert (Has_Suffix (Node (ADT), 'Y'));
1652                Next_Elmt (ADT);
1653
1654                --  Skip secondary dispatch table referencing user-defined
1655                --  primitives covered by this interface.
1656
1657                pragma Assert (Has_Suffix (Node (ADT), 'D'));
1658                Next_Elmt (ADT);
1659
1660                --  Skip secondary dispatch table referencing predefined
1661                --  primitives.
1662
1663                pragma Assert (Has_Suffix (Node (ADT), 'Z'));
1664                Next_Elmt (ADT);
1665             end if;
1666          end loop;
1667
1668          pragma Assert (Is_Tag (Node (ADT)));
1669          return Node (ADT);
1670       end Search_Tag;
1671
1672    --  Start of processing for Collect_Interfaces_Info
1673
1674    begin
1675       Collect_Interfaces (T, Ifaces_List);
1676       Collect_Interface_Components (T, Comps_List);
1677
1678       --  Search for the record component and tag associated with each
1679       --  interface type of T.
1680
1681       Components_List := New_Elmt_List;
1682       Tags_List       := New_Elmt_List;
1683
1684       Iface_Elmt := First_Elmt (Ifaces_List);
1685       while Present (Iface_Elmt) loop
1686          Iface := Node (Iface_Elmt);
1687
1688          --  Associate the primary tag component and the primary dispatch table
1689          --  with all the interfaces that are parents of T
1690
1691          if Is_Ancestor (Iface, T, Use_Full_View => True) then
1692             Append_Elmt (First_Tag_Component (T), Components_List);
1693             Append_Elmt (Node (First_Elmt (Access_Disp_Table (T))), Tags_List);
1694
1695          --  Otherwise search for the tag component and secondary dispatch
1696          --  table of Iface
1697
1698          else
1699             Comp_Elmt := First_Elmt (Comps_List);
1700             while Present (Comp_Elmt) loop
1701                Comp_Iface := Related_Type (Node (Comp_Elmt));
1702
1703                if Comp_Iface = Iface
1704                  or else Is_Ancestor (Iface, Comp_Iface, Use_Full_View => True)
1705                then
1706                   Append_Elmt (Node (Comp_Elmt), Components_List);
1707                   Append_Elmt (Search_Tag (Comp_Iface), Tags_List);
1708                   exit;
1709                end if;
1710
1711                Next_Elmt (Comp_Elmt);
1712             end loop;
1713             pragma Assert (Present (Comp_Elmt));
1714          end if;
1715
1716          Next_Elmt (Iface_Elmt);
1717       end loop;
1718    end Collect_Interfaces_Info;
1719
1720    ---------------------
1721    -- Collect_Parents --
1722    ---------------------
1723
1724    procedure Collect_Parents
1725      (T             : Entity_Id;
1726       List          : out Elist_Id;
1727       Use_Full_View : Boolean := True)
1728    is
1729       Current_Typ : Entity_Id := T;
1730       Parent_Typ  : Entity_Id;
1731
1732    begin
1733       List := New_Elmt_List;
1734
1735       --  No action if the if the type has no parents
1736
1737       if T = Etype (T) then
1738          return;
1739       end if;
1740
1741       loop
1742          Parent_Typ := Etype (Current_Typ);
1743
1744          if Is_Private_Type (Parent_Typ)
1745            and then Present (Full_View (Parent_Typ))
1746            and then Use_Full_View
1747          then
1748             Parent_Typ := Full_View (Base_Type (Parent_Typ));
1749          end if;
1750
1751          Append_Elmt (Parent_Typ, List);
1752
1753          exit when Parent_Typ = Current_Typ;
1754          Current_Typ := Parent_Typ;
1755       end loop;
1756    end Collect_Parents;
1757
1758    ----------------------------------
1759    -- Collect_Primitive_Operations --
1760    ----------------------------------
1761
1762    function Collect_Primitive_Operations (T : Entity_Id) return Elist_Id is
1763       B_Type         : constant Entity_Id := Base_Type (T);
1764       B_Decl         : constant Node_Id   := Original_Node (Parent (B_Type));
1765       B_Scope        : Entity_Id          := Scope (B_Type);
1766       Op_List        : Elist_Id;
1767       Formal         : Entity_Id;
1768       Is_Prim        : Boolean;
1769       Formal_Derived : Boolean := False;
1770       Id             : Entity_Id;
1771
1772       function Match (E : Entity_Id) return Boolean;
1773       --  True if E's base type is B_Type, or E is of an anonymous access type
1774       --  and the base type of its designated type is B_Type.
1775
1776       -----------
1777       -- Match --
1778       -----------
1779
1780       function Match (E : Entity_Id) return Boolean is
1781          Etyp : Entity_Id := Etype (E);
1782
1783       begin
1784          if Ekind (Etyp) = E_Anonymous_Access_Type then
1785             Etyp := Designated_Type (Etyp);
1786          end if;
1787
1788          return Base_Type (Etyp) = B_Type;
1789       end Match;
1790
1791    --  Start of processing for Collect_Primitive_Operations
1792
1793    begin
1794       --  For tagged types, the primitive operations are collected as they
1795       --  are declared, and held in an explicit list which is simply returned.
1796
1797       if Is_Tagged_Type (B_Type) then
1798          return Primitive_Operations (B_Type);
1799
1800       --  An untagged generic type that is a derived type inherits the
1801       --  primitive operations of its parent type. Other formal types only
1802       --  have predefined operators, which are not explicitly represented.
1803
1804       elsif Is_Generic_Type (B_Type) then
1805          if Nkind (B_Decl) = N_Formal_Type_Declaration
1806            and then Nkind (Formal_Type_Definition (B_Decl))
1807              = N_Formal_Derived_Type_Definition
1808          then
1809             Formal_Derived := True;
1810          else
1811             return New_Elmt_List;
1812          end if;
1813       end if;
1814
1815       Op_List := New_Elmt_List;
1816
1817       if B_Scope = Standard_Standard then
1818          if B_Type = Standard_String then
1819             Append_Elmt (Standard_Op_Concat, Op_List);
1820
1821          elsif B_Type = Standard_Wide_String then
1822             Append_Elmt (Standard_Op_Concatw, Op_List);
1823
1824          else
1825             null;
1826          end if;
1827
1828       elsif (Is_Package_Or_Generic_Package (B_Scope)
1829               and then
1830                 Nkind (Parent (Declaration_Node (First_Subtype (T)))) /=
1831                                                             N_Package_Body)
1832         or else Is_Derived_Type (B_Type)
1833       then
1834          --  The primitive operations appear after the base type, except
1835          --  if the derivation happens within the private part of B_Scope
1836          --  and the type is a private type, in which case both the type
1837          --  and some primitive operations may appear before the base
1838          --  type, and the list of candidates starts after the type.
1839
1840          if In_Open_Scopes (B_Scope)
1841            and then Scope (T) = B_Scope
1842            and then In_Private_Part (B_Scope)
1843          then
1844             Id := Next_Entity (T);
1845          else
1846             Id := Next_Entity (B_Type);
1847          end if;
1848
1849          while Present (Id) loop
1850
1851             --  Note that generic formal subprograms are not
1852             --  considered to be primitive operations and thus
1853             --  are never inherited.
1854
1855             if Is_Overloadable (Id)
1856               and then Nkind (Parent (Parent (Id)))
1857                          not in N_Formal_Subprogram_Declaration
1858             then
1859                Is_Prim := False;
1860
1861                if Match (Id) then
1862                   Is_Prim := True;
1863
1864                else
1865                   Formal := First_Formal (Id);
1866                   while Present (Formal) loop
1867                      if Match (Formal) then
1868                         Is_Prim := True;
1869                         exit;
1870                      end if;
1871
1872                      Next_Formal (Formal);
1873                   end loop;
1874                end if;
1875
1876                --  For a formal derived type, the only primitives are the
1877                --  ones inherited from the parent type. Operations appearing
1878                --  in the package declaration are not primitive for it.
1879
1880                if Is_Prim
1881                  and then (not Formal_Derived
1882                             or else Present (Alias (Id)))
1883                then
1884                   --  In the special case of an equality operator aliased to
1885                   --  an overriding dispatching equality belonging to the same
1886                   --  type, we don't include it in the list of primitives.
1887                   --  This avoids inheriting multiple equality operators when
1888                   --  deriving from untagged private types whose full type is
1889                   --  tagged, which can otherwise cause ambiguities. Note that
1890                   --  this should only happen for this kind of untagged parent
1891                   --  type, since normally dispatching operations are inherited
1892                   --  using the type's Primitive_Operations list.
1893
1894                   if Chars (Id) = Name_Op_Eq
1895                     and then Is_Dispatching_Operation (Id)
1896                     and then Present (Alias (Id))
1897                     and then Present (Overridden_Operation (Alias (Id)))
1898                     and then Base_Type (Etype (First_Entity (Id))) =
1899                                Base_Type (Etype (First_Entity (Alias (Id))))
1900                   then
1901                      null;
1902
1903                   --  Include the subprogram in the list of primitives
1904
1905                   else
1906                      Append_Elmt (Id, Op_List);
1907                   end if;
1908                end if;
1909             end if;
1910
1911             Next_Entity (Id);
1912
1913             --  For a type declared in System, some of its operations may
1914             --  appear in the target-specific extension to System.
1915
1916             if No (Id)
1917               and then B_Scope = RTU_Entity (System)
1918               and then Present_System_Aux
1919             then
1920                B_Scope := System_Aux_Id;
1921                Id := First_Entity (System_Aux_Id);
1922             end if;
1923          end loop;
1924       end if;
1925
1926       return Op_List;
1927    end Collect_Primitive_Operations;
1928
1929    -----------------------------------
1930    -- Compile_Time_Constraint_Error --
1931    -----------------------------------
1932
1933    function Compile_Time_Constraint_Error
1934      (N    : Node_Id;
1935       Msg  : String;
1936       Ent  : Entity_Id  := Empty;
1937       Loc  : Source_Ptr := No_Location;
1938       Warn : Boolean    := False) return Node_Id
1939    is
1940       Msgc : String (1 .. Msg'Length + 2);
1941       --  Copy of message, with room for possible ? and ! at end
1942
1943       Msgl : Natural;
1944       Wmsg : Boolean;
1945       P    : Node_Id;
1946       OldP : Node_Id;
1947       Msgs : Boolean;
1948       Eloc : Source_Ptr;
1949
1950    begin
1951       --  A static constraint error in an instance body is not a fatal error.
1952       --  we choose to inhibit the message altogether, because there is no
1953       --  obvious node (for now) on which to post it. On the other hand the
1954       --  offending node must be replaced with a constraint_error in any case.
1955
1956       --  No messages are generated if we already posted an error on this node
1957
1958       if not Error_Posted (N) then
1959          if Loc /= No_Location then
1960             Eloc := Loc;
1961          else
1962             Eloc := Sloc (N);
1963          end if;
1964
1965          Msgc (1 .. Msg'Length) := Msg;
1966          Msgl := Msg'Length;
1967
1968          --  Message is a warning, even in Ada 95 case
1969
1970          if Msg (Msg'Last) = '?' then
1971             Wmsg := True;
1972
1973          --  In Ada 83, all messages are warnings. In the private part and
1974          --  the body of an instance, constraint_checks are only warnings.
1975          --  We also make this a warning if the Warn parameter is set.
1976
1977          elsif Warn
1978            or else (Ada_Version = Ada_83 and then Comes_From_Source (N))
1979          then
1980             Msgl := Msgl + 1;
1981             Msgc (Msgl) := '?';
1982             Wmsg := True;
1983
1984          elsif In_Instance_Not_Visible then
1985             Msgl := Msgl + 1;
1986             Msgc (Msgl) := '?';
1987             Wmsg := True;
1988
1989          --  Otherwise we have a real error message (Ada 95 static case)
1990          --  and we make this an unconditional message. Note that in the
1991          --  warning case we do not make the message unconditional, it seems
1992          --  quite reasonable to delete messages like this (about exceptions
1993          --  that will be raised) in dead code.
1994
1995          else
1996             Wmsg := False;
1997             Msgl := Msgl + 1;
1998             Msgc (Msgl) := '!';
1999          end if;
2000
2001          --  Should we generate a warning? The answer is not quite yes. The
2002          --  very annoying exception occurs in the case of a short circuit
2003          --  operator where the left operand is static and decisive. Climb
2004          --  parents to see if that is the case we have here. Conditional
2005          --  expressions with decisive conditions are a similar situation.
2006
2007          Msgs := True;
2008          P := N;
2009          loop
2010             OldP := P;
2011             P := Parent (P);
2012
2013             --  And then with False as left operand
2014
2015             if Nkind (P) = N_And_Then
2016               and then Compile_Time_Known_Value (Left_Opnd (P))
2017               and then Is_False (Expr_Value (Left_Opnd (P)))
2018             then
2019                Msgs := False;
2020                exit;
2021
2022             --  OR ELSE with True as left operand
2023
2024             elsif Nkind (P) = N_Or_Else
2025               and then Compile_Time_Known_Value (Left_Opnd (P))
2026               and then Is_True (Expr_Value (Left_Opnd (P)))
2027             then
2028                Msgs := False;
2029                exit;
2030
2031             --  Conditional expression
2032
2033             elsif Nkind (P) = N_Conditional_Expression then
2034                declare
2035                   Cond : constant Node_Id := First (Expressions (P));
2036                   Texp : constant Node_Id := Next (Cond);
2037                   Fexp : constant Node_Id := Next (Texp);
2038
2039                begin
2040                   if Compile_Time_Known_Value (Cond) then
2041
2042                      --  Condition is True and we are in the right operand
2043
2044                      if Is_True (Expr_Value (Cond))
2045                        and then OldP = Fexp
2046                      then
2047                         Msgs := False;
2048                         exit;
2049
2050                      --  Condition is False and we are in the left operand
2051
2052                      elsif Is_False (Expr_Value (Cond))
2053                        and then OldP = Texp
2054                      then
2055                         Msgs := False;
2056                         exit;
2057                      end if;
2058                   end if;
2059                end;
2060
2061             --  Special case for component association in aggregates, where
2062             --  we want to keep climbing up to the parent aggregate.
2063
2064             elsif Nkind (P) = N_Component_Association
2065               and then Nkind (Parent (P)) = N_Aggregate
2066             then
2067                null;
2068
2069             --  Keep going if within subexpression
2070
2071             else
2072                exit when Nkind (P) not in N_Subexpr;
2073             end if;
2074          end loop;
2075
2076          if Msgs then
2077             if Present (Ent) then
2078                Error_Msg_NEL (Msgc (1 .. Msgl), N, Ent, Eloc);
2079             else
2080                Error_Msg_NEL (Msgc (1 .. Msgl), N, Etype (N), Eloc);
2081             end if;
2082
2083             if Wmsg then
2084                if Inside_Init_Proc then
2085                   Error_Msg_NEL
2086                     ("\?& will be raised for objects of this type",
2087                      N, Standard_Constraint_Error, Eloc);
2088                else
2089                   Error_Msg_NEL
2090                     ("\?& will be raised at run time",
2091                      N, Standard_Constraint_Error, Eloc);
2092                end if;
2093
2094             else
2095                Error_Msg
2096                  ("\static expression fails Constraint_Check", Eloc);
2097                Set_Error_Posted (N);
2098             end if;
2099          end if;
2100       end if;
2101
2102       return N;
2103    end Compile_Time_Constraint_Error;
2104
2105    -----------------------
2106    -- Conditional_Delay --
2107    -----------------------
2108
2109    procedure Conditional_Delay (New_Ent, Old_Ent : Entity_Id) is
2110    begin
2111       if Has_Delayed_Freeze (Old_Ent) and then not Is_Frozen (Old_Ent) then
2112          Set_Has_Delayed_Freeze (New_Ent);
2113       end if;
2114    end Conditional_Delay;
2115
2116    -------------------------
2117    -- Copy_Parameter_List --
2118    -------------------------
2119
2120    function Copy_Parameter_List (Subp_Id : Entity_Id) return List_Id is
2121       Loc    : constant Source_Ptr := Sloc (Subp_Id);
2122       Plist  : List_Id;
2123       Formal : Entity_Id;
2124
2125    begin
2126       if No (First_Formal (Subp_Id)) then
2127          return No_List;
2128       else
2129          Plist := New_List;
2130          Formal := First_Formal (Subp_Id);
2131          while Present (Formal) loop
2132             Append
2133               (Make_Parameter_Specification (Loc,
2134                 Defining_Identifier =>
2135                   Make_Defining_Identifier (Sloc (Formal),
2136                     Chars => Chars (Formal)),
2137                 In_Present  => In_Present (Parent (Formal)),
2138                 Out_Present => Out_Present (Parent (Formal)),
2139              Parameter_Type =>
2140                   New_Reference_To (Etype (Formal), Loc),
2141                 Expression =>
2142                   New_Copy_Tree (Expression (Parent (Formal)))),
2143               Plist);
2144
2145             Next_Formal (Formal);
2146          end loop;
2147       end if;
2148
2149       return Plist;
2150    end Copy_Parameter_List;
2151
2152    --------------------
2153    -- Current_Entity --
2154    --------------------
2155
2156    --  The currently visible definition for a given identifier is the
2157    --  one most chained at the start of the visibility chain, i.e. the
2158    --  one that is referenced by the Node_Id value of the name of the
2159    --  given identifier.
2160
2161    function Current_Entity (N : Node_Id) return Entity_Id is
2162    begin
2163       return Get_Name_Entity_Id (Chars (N));
2164    end Current_Entity;
2165
2166    -----------------------------
2167    -- Current_Entity_In_Scope --
2168    -----------------------------
2169
2170    function Current_Entity_In_Scope (N : Node_Id) return Entity_Id is
2171       E  : Entity_Id;
2172       CS : constant Entity_Id := Current_Scope;
2173
2174       Transient_Case : constant Boolean := Scope_Is_Transient;
2175
2176    begin
2177       E := Get_Name_Entity_Id (Chars (N));
2178       while Present (E)
2179         and then Scope (E) /= CS
2180         and then (not Transient_Case or else Scope (E) /= Scope (CS))
2181       loop
2182          E := Homonym (E);
2183       end loop;
2184
2185       return E;
2186    end Current_Entity_In_Scope;
2187
2188    -------------------
2189    -- Current_Scope --
2190    -------------------
2191
2192    function Current_Scope return Entity_Id is
2193    begin
2194       if Scope_Stack.Last = -1 then
2195          return Standard_Standard;
2196       else
2197          declare
2198             C : constant Entity_Id :=
2199                   Scope_Stack.Table (Scope_Stack.Last).Entity;
2200          begin
2201             if Present (C) then
2202                return C;
2203             else
2204                return Standard_Standard;
2205             end if;
2206          end;
2207       end if;
2208    end Current_Scope;
2209
2210    ------------------------
2211    -- Current_Subprogram --
2212    ------------------------
2213
2214    function Current_Subprogram return Entity_Id is
2215       Scop : constant Entity_Id := Current_Scope;
2216    begin
2217       if Is_Subprogram (Scop) or else Is_Generic_Subprogram (Scop) then
2218          return Scop;
2219       else
2220          return Enclosing_Subprogram (Scop);
2221       end if;
2222    end Current_Subprogram;
2223
2224    ---------------------
2225    -- Defining_Entity --
2226    ---------------------
2227
2228    function Defining_Entity (N : Node_Id) return Entity_Id is
2229       K   : constant Node_Kind := Nkind (N);
2230       Err : Entity_Id := Empty;
2231
2232    begin
2233       case K is
2234          when
2235            N_Subprogram_Declaration                 |
2236            N_Abstract_Subprogram_Declaration        |
2237            N_Subprogram_Body                        |
2238            N_Package_Declaration                    |
2239            N_Subprogram_Renaming_Declaration        |
2240            N_Subprogram_Body_Stub                   |
2241            N_Generic_Subprogram_Declaration         |
2242            N_Generic_Package_Declaration            |
2243            N_Formal_Subprogram_Declaration
2244          =>
2245             return Defining_Entity (Specification (N));
2246
2247          when
2248            N_Component_Declaration                  |
2249            N_Defining_Program_Unit_Name             |
2250            N_Discriminant_Specification             |
2251            N_Entry_Body                             |
2252            N_Entry_Declaration                      |
2253            N_Entry_Index_Specification              |
2254            N_Exception_Declaration                  |
2255            N_Exception_Renaming_Declaration         |
2256            N_Formal_Object_Declaration              |
2257            N_Formal_Package_Declaration             |
2258            N_Formal_Type_Declaration                |
2259            N_Full_Type_Declaration                  |
2260            N_Implicit_Label_Declaration             |
2261            N_Incomplete_Type_Declaration            |
2262            N_Loop_Parameter_Specification           |
2263            N_Number_Declaration                     |
2264            N_Object_Declaration                     |
2265            N_Object_Renaming_Declaration            |
2266            N_Package_Body_Stub                      |
2267            N_Parameter_Specification                |
2268            N_Private_Extension_Declaration          |
2269            N_Private_Type_Declaration               |
2270            N_Protected_Body                         |
2271            N_Protected_Body_Stub                    |
2272            N_Protected_Type_Declaration             |
2273            N_Single_Protected_Declaration           |
2274            N_Single_Task_Declaration                |
2275            N_Subtype_Declaration                    |
2276            N_Task_Body                              |
2277            N_Task_Body_Stub                         |
2278            N_Task_Type_Declaration
2279          =>
2280             return Defining_Identifier (N);
2281
2282          when N_Subunit =>
2283             return Defining_Entity (Proper_Body (N));
2284
2285          when
2286            N_Function_Instantiation                 |
2287            N_Function_Specification                 |
2288            N_Generic_Function_Renaming_Declaration  |
2289            N_Generic_Package_Renaming_Declaration   |
2290            N_Generic_Procedure_Renaming_Declaration |
2291            N_Package_Body                           |
2292            N_Package_Instantiation                  |
2293            N_Package_Renaming_Declaration           |
2294            N_Package_Specification                  |
2295            N_Procedure_Instantiation                |
2296            N_Procedure_Specification
2297          =>
2298             declare
2299                Nam : constant Node_Id := Defining_Unit_Name (N);
2300
2301             begin
2302                if Nkind (Nam) in N_Entity then
2303                   return Nam;
2304
2305                --  For Error, make up a name and attach to declaration
2306                --  so we can continue semantic analysis
2307
2308                elsif Nam = Error then
2309                   Err := Make_Temporary (Sloc (N), 'T');
2310                   Set_Defining_Unit_Name (N, Err);
2311
2312                   return Err;
2313                --  If not an entity, get defining identifier
2314
2315                else
2316                   return Defining_Identifier (Nam);
2317                end if;
2318             end;
2319
2320          when N_Block_Statement =>
2321             return Entity (Identifier (N));
2322
2323          when others =>
2324             raise Program_Error;
2325
2326       end case;
2327    end Defining_Entity;
2328
2329    --------------------------
2330    -- Denotes_Discriminant --
2331    --------------------------
2332
2333    function Denotes_Discriminant
2334      (N                : Node_Id;
2335       Check_Concurrent : Boolean := False) return Boolean
2336    is
2337       E : Entity_Id;
2338    begin
2339       if not Is_Entity_Name (N)
2340         or else No (Entity (N))
2341       then
2342          return False;
2343       else
2344          E := Entity (N);
2345       end if;
2346
2347       --  If we are checking for a protected type, the discriminant may have
2348       --  been rewritten as the corresponding discriminal of the original type
2349       --  or of the corresponding concurrent record, depending on whether we
2350       --  are in the spec or body of the protected type.
2351
2352       return Ekind (E) = E_Discriminant
2353         or else
2354           (Check_Concurrent
2355             and then Ekind (E) = E_In_Parameter
2356             and then Present (Discriminal_Link (E))
2357             and then
2358               (Is_Concurrent_Type (Scope (Discriminal_Link (E)))
2359                 or else
2360                   Is_Concurrent_Record_Type (Scope (Discriminal_Link (E)))));
2361
2362    end Denotes_Discriminant;
2363
2364    -------------------------
2365    -- Denotes_Same_Object --
2366    -------------------------
2367
2368    function Denotes_Same_Object (A1, A2 : Node_Id) return Boolean is
2369       Obj1 : Node_Id := A1;
2370       Obj2 : Node_Id := A2;
2371
2372       procedure Check_Renaming (Obj : in out Node_Id);
2373       --  If an object is a renaming, examine renamed object. If it is a
2374       --  dereference of a variable, or an indexed expression with non-constant
2375       --  indexes, no overlap check can be reported.
2376
2377       --------------------
2378       -- Check_Renaming --
2379       --------------------
2380
2381       procedure Check_Renaming (Obj : in out Node_Id) is
2382       begin
2383          if Is_Entity_Name (Obj)
2384            and then Present (Renamed_Entity (Entity (Obj)))
2385          then
2386             Obj := Renamed_Entity (Entity (Obj));
2387             if Nkind (Obj) = N_Explicit_Dereference
2388               and then Is_Variable (Prefix (Obj))
2389             then
2390                Obj := Empty;
2391
2392             elsif Nkind (Obj) = N_Indexed_Component then
2393                declare
2394                   Indx : Node_Id;
2395
2396                begin
2397                   Indx := First (Expressions (Obj));
2398                   while Present (Indx) loop
2399                      if not Is_OK_Static_Expression (Indx) then
2400                         Obj := Empty;
2401                         exit;
2402                      end if;
2403
2404                      Next_Index (Indx);
2405                   end loop;
2406                end;
2407             end if;
2408          end if;
2409       end Check_Renaming;
2410
2411    --  Start of processing for Denotes_Same_Object
2412
2413    begin
2414       Check_Renaming (Obj1);
2415       Check_Renaming (Obj2);
2416
2417       if No (Obj1)
2418         or else No (Obj2)
2419       then
2420          return False;
2421       end if;
2422
2423       --  If we have entity names, then must be same entity
2424
2425       if Is_Entity_Name (Obj1) then
2426          if Is_Entity_Name (Obj2) then
2427             return Entity (Obj1) = Entity (Obj2);
2428          else
2429             return False;
2430          end if;
2431
2432       --  No match if not same node kind
2433
2434       elsif Nkind (Obj1) /= Nkind (Obj2) then
2435          return False;
2436
2437       --  For selected components, must have same prefix and selector
2438
2439       elsif Nkind (Obj1) = N_Selected_Component then
2440          return Denotes_Same_Object (Prefix (Obj1), Prefix (Obj2))
2441            and then
2442          Entity (Selector_Name (Obj1)) = Entity (Selector_Name (Obj2));
2443
2444       --  For explicit dereferences, prefixes must be same
2445
2446       elsif Nkind (Obj1) = N_Explicit_Dereference then
2447          return Denotes_Same_Object (Prefix (Obj1), Prefix (Obj2));
2448
2449       --  For indexed components, prefixes and all subscripts must be the same
2450
2451       elsif Nkind (Obj1) = N_Indexed_Component then
2452          if Denotes_Same_Object (Prefix (Obj1), Prefix (Obj2)) then
2453             declare
2454                Indx1 : Node_Id;
2455                Indx2 : Node_Id;
2456
2457             begin
2458                Indx1 := First (Expressions (Obj1));
2459                Indx2 := First (Expressions (Obj2));
2460                while Present (Indx1) loop
2461
2462                   --  Indexes must denote the same static value or same object
2463
2464                   if Is_OK_Static_Expression (Indx1) then
2465                      if not Is_OK_Static_Expression (Indx2) then
2466                         return False;
2467
2468                      elsif Expr_Value (Indx1) /= Expr_Value (Indx2) then
2469                         return False;
2470                      end if;
2471
2472                   elsif not Denotes_Same_Object (Indx1, Indx2) then
2473                      return False;
2474                   end if;
2475
2476                   Next (Indx1);
2477                   Next (Indx2);
2478                end loop;
2479
2480                return True;
2481             end;
2482          else
2483             return False;
2484          end if;
2485
2486       --  For slices, prefixes must match and bounds must match
2487
2488       elsif Nkind (Obj1) = N_Slice
2489         and then Denotes_Same_Object (Prefix (Obj1), Prefix (Obj2))
2490       then
2491          declare
2492             Lo1, Lo2, Hi1, Hi2 : Node_Id;
2493
2494          begin
2495             Get_Index_Bounds (Etype (Obj1), Lo1, Hi1);
2496             Get_Index_Bounds (Etype (Obj2), Lo2, Hi2);
2497
2498             --  Check whether bounds are statically identical. There is no
2499             --  attempt to detect partial overlap of slices.
2500
2501             return Denotes_Same_Object (Lo1, Lo2)
2502               and then Denotes_Same_Object (Hi1, Hi2);
2503          end;
2504
2505          --  Literals will appear as indexes. Isn't this where we should check
2506          --  Known_At_Compile_Time at least if we are generating warnings ???
2507
2508       elsif Nkind (Obj1) = N_Integer_Literal then
2509          return Intval (Obj1) = Intval (Obj2);
2510
2511       else
2512          return False;
2513       end if;
2514    end Denotes_Same_Object;
2515
2516    -------------------------
2517    -- Denotes_Same_Prefix --
2518    -------------------------
2519
2520    function Denotes_Same_Prefix (A1, A2 : Node_Id) return Boolean is
2521
2522    begin
2523       if Is_Entity_Name (A1) then
2524          if Nkind_In (A2, N_Selected_Component, N_Indexed_Component)
2525            and then not Is_Access_Type (Etype (A1))
2526          then
2527             return Denotes_Same_Object (A1, Prefix (A2))
2528               or else Denotes_Same_Prefix (A1, Prefix (A2));
2529          else
2530             return False;
2531          end if;
2532
2533       elsif Is_Entity_Name (A2) then
2534          return Denotes_Same_Prefix (A2, A1);
2535
2536       elsif Nkind_In (A1, N_Selected_Component, N_Indexed_Component, N_Slice)
2537               and then
2538             Nkind_In (A2, N_Selected_Component, N_Indexed_Component, N_Slice)
2539       then
2540          declare
2541             Root1, Root2 : Node_Id;
2542             Depth1, Depth2 : Int := 0;
2543
2544          begin
2545             Root1 := Prefix (A1);
2546             while not Is_Entity_Name (Root1) loop
2547                if not Nkind_In
2548                  (Root1, N_Selected_Component, N_Indexed_Component)
2549                then
2550                   return False;
2551                else
2552                   Root1 := Prefix (Root1);
2553                end if;
2554
2555                Depth1 := Depth1 + 1;
2556             end loop;
2557
2558             Root2 := Prefix (A2);
2559             while not Is_Entity_Name (Root2) loop
2560                if not Nkind_In
2561                  (Root2, N_Selected_Component, N_Indexed_Component)
2562                then
2563                   return False;
2564                else
2565                   Root2 := Prefix (Root2);
2566                end if;
2567
2568                Depth2 := Depth2 + 1;
2569             end loop;
2570
2571             --  If both have the same depth and they do not denote the same
2572             --  object, they are disjoint and not warning is needed.
2573
2574             if Depth1 = Depth2 then
2575                return False;
2576
2577             elsif Depth1 > Depth2 then
2578                Root1 := Prefix (A1);
2579                for I in 1 .. Depth1 - Depth2 - 1 loop
2580                   Root1 := Prefix (Root1);
2581                end loop;
2582
2583                return Denotes_Same_Object (Root1, A2);
2584
2585             else
2586                Root2 := Prefix (A2);
2587                for I in 1 .. Depth2 - Depth1 - 1 loop
2588                   Root2 := Prefix (Root2);
2589                end loop;
2590
2591                return Denotes_Same_Object (A1, Root2);
2592             end if;
2593          end;
2594
2595       else
2596          return False;
2597       end if;
2598    end Denotes_Same_Prefix;
2599
2600    ----------------------
2601    -- Denotes_Variable --
2602    ----------------------
2603
2604    function Denotes_Variable (N : Node_Id) return Boolean is
2605    begin
2606       return Is_Variable (N) and then Paren_Count (N) = 0;
2607    end Denotes_Variable;
2608
2609    -----------------------------
2610    -- Depends_On_Discriminant --
2611    -----------------------------
2612
2613    function Depends_On_Discriminant (N : Node_Id) return Boolean is
2614       L : Node_Id;
2615       H : Node_Id;
2616
2617    begin
2618       Get_Index_Bounds (N, L, H);
2619       return Denotes_Discriminant (L) or else Denotes_Discriminant (H);
2620    end Depends_On_Discriminant;
2621
2622    -------------------------
2623    -- Designate_Same_Unit --
2624    -------------------------
2625
2626    function Designate_Same_Unit
2627      (Name1 : Node_Id;
2628       Name2 : Node_Id) return Boolean
2629    is
2630       K1 : constant Node_Kind := Nkind (Name1);
2631       K2 : constant Node_Kind := Nkind (Name2);
2632
2633       function Prefix_Node (N : Node_Id) return Node_Id;
2634       --  Returns the parent unit name node of a defining program unit name
2635       --  or the prefix if N is a selected component or an expanded name.
2636
2637       function Select_Node (N : Node_Id) return Node_Id;
2638       --  Returns the defining identifier node of a defining program unit
2639       --  name or  the selector node if N is a selected component or an
2640       --  expanded name.
2641
2642       -----------------
2643       -- Prefix_Node --
2644       -----------------
2645
2646       function Prefix_Node (N : Node_Id) return Node_Id is
2647       begin
2648          if Nkind (N) = N_Defining_Program_Unit_Name then
2649             return Name (N);
2650
2651          else
2652             return Prefix (N);
2653          end if;
2654       end Prefix_Node;
2655
2656       -----------------
2657       -- Select_Node --
2658       -----------------
2659
2660       function Select_Node (N : Node_Id) return Node_Id is
2661       begin
2662          if Nkind (N) = N_Defining_Program_Unit_Name then
2663             return Defining_Identifier (N);
2664
2665          else
2666             return Selector_Name (N);
2667          end if;
2668       end Select_Node;
2669
2670    --  Start of processing for Designate_Next_Unit
2671
2672    begin
2673       if (K1 = N_Identifier or else
2674           K1 = N_Defining_Identifier)
2675         and then
2676          (K2 = N_Identifier or else
2677           K2 = N_Defining_Identifier)
2678       then
2679          return Chars (Name1) = Chars (Name2);
2680
2681       elsif
2682          (K1 = N_Expanded_Name      or else
2683           K1 = N_Selected_Component or else
2684           K1 = N_Defining_Program_Unit_Name)
2685         and then
2686          (K2 = N_Expanded_Name      or else
2687           K2 = N_Selected_Component or else
2688           K2 = N_Defining_Program_Unit_Name)
2689       then
2690          return
2691            (Chars (Select_Node (Name1)) = Chars (Select_Node (Name2)))
2692              and then
2693                Designate_Same_Unit (Prefix_Node (Name1), Prefix_Node (Name2));
2694
2695       else
2696          return False;
2697       end if;
2698    end Designate_Same_Unit;
2699
2700    --------------------------
2701    -- Enclosing_CPP_Parent --
2702    --------------------------
2703
2704    function Enclosing_CPP_Parent (Typ : Entity_Id) return Entity_Id is
2705       Parent_Typ : Entity_Id := Typ;
2706
2707    begin
2708       while not Is_CPP_Class (Parent_Typ)
2709          and then Etype (Parent_Typ) /= Parent_Typ
2710       loop
2711          Parent_Typ := Etype (Parent_Typ);
2712
2713          if Is_Private_Type (Parent_Typ) then
2714             Parent_Typ := Full_View (Base_Type (Parent_Typ));
2715          end if;
2716       end loop;
2717
2718       pragma Assert (Is_CPP_Class (Parent_Typ));
2719       return Parent_Typ;
2720    end Enclosing_CPP_Parent;
2721
2722    ----------------------------
2723    -- Enclosing_Generic_Body --
2724    ----------------------------
2725
2726    function Enclosing_Generic_Body
2727      (N : Node_Id) return Node_Id
2728    is
2729       P    : Node_Id;
2730       Decl : Node_Id;
2731       Spec : Node_Id;
2732
2733    begin
2734       P := Parent (N);
2735       while Present (P) loop
2736          if Nkind (P) = N_Package_Body
2737            or else Nkind (P) = N_Subprogram_Body
2738          then
2739             Spec := Corresponding_Spec (P);
2740
2741             if Present (Spec) then
2742                Decl := Unit_Declaration_Node (Spec);
2743
2744                if Nkind (Decl) = N_Generic_Package_Declaration
2745                  or else Nkind (Decl) = N_Generic_Subprogram_Declaration
2746                then
2747                   return P;
2748                end if;
2749             end if;
2750          end if;
2751
2752          P := Parent (P);
2753       end loop;
2754
2755       return Empty;
2756    end Enclosing_Generic_Body;
2757
2758    ----------------------------
2759    -- Enclosing_Generic_Unit --
2760    ----------------------------
2761
2762    function Enclosing_Generic_Unit
2763      (N : Node_Id) return Node_Id
2764    is
2765       P    : Node_Id;
2766       Decl : Node_Id;
2767       Spec : Node_Id;
2768
2769    begin
2770       P := Parent (N);
2771       while Present (P) loop
2772          if Nkind (P) = N_Generic_Package_Declaration
2773            or else Nkind (P) = N_Generic_Subprogram_Declaration
2774          then
2775             return P;
2776
2777          elsif Nkind (P) = N_Package_Body
2778            or else Nkind (P) = N_Subprogram_Body
2779          then
2780             Spec := Corresponding_Spec (P);
2781
2782             if Present (Spec) then
2783                Decl := Unit_Declaration_Node (Spec);
2784
2785                if Nkind (Decl) = N_Generic_Package_Declaration
2786                  or else Nkind (Decl) = N_Generic_Subprogram_Declaration
2787                then
2788                   return Decl;
2789                end if;
2790             end if;
2791          end if;
2792
2793          P := Parent (P);
2794       end loop;
2795
2796       return Empty;
2797    end Enclosing_Generic_Unit;
2798
2799    -------------------------------
2800    -- Enclosing_Lib_Unit_Entity --
2801    -------------------------------
2802
2803    function Enclosing_Lib_Unit_Entity return Entity_Id is
2804       Unit_Entity : Entity_Id;
2805
2806    begin
2807       --  Look for enclosing library unit entity by following scope links.
2808       --  Equivalent to, but faster than indexing through the scope stack.
2809
2810       Unit_Entity := Current_Scope;
2811       while (Present (Scope (Unit_Entity))
2812         and then Scope (Unit_Entity) /= Standard_Standard)
2813         and not Is_Child_Unit (Unit_Entity)
2814       loop
2815          Unit_Entity := Scope (Unit_Entity);
2816       end loop;
2817
2818       return Unit_Entity;
2819    end Enclosing_Lib_Unit_Entity;
2820
2821    -----------------------------
2822    -- Enclosing_Lib_Unit_Node --
2823    -----------------------------
2824
2825    function Enclosing_Lib_Unit_Node (N : Node_Id) return Node_Id is
2826       Current_Node : Node_Id;
2827
2828    begin
2829       Current_Node := N;
2830       while Present (Current_Node)
2831         and then Nkind (Current_Node) /= N_Compilation_Unit
2832       loop
2833          Current_Node := Parent (Current_Node);
2834       end loop;
2835
2836       if Nkind (Current_Node) /= N_Compilation_Unit then
2837          return Empty;
2838       end if;
2839
2840       return Current_Node;
2841    end Enclosing_Lib_Unit_Node;
2842
2843    --------------------------
2844    -- Enclosing_Subprogram --
2845    --------------------------
2846
2847    function Enclosing_Subprogram (E : Entity_Id) return Entity_Id is
2848       Dynamic_Scope : constant Entity_Id := Enclosing_Dynamic_Scope (E);
2849
2850    begin
2851       if Dynamic_Scope = Standard_Standard then
2852          return Empty;
2853
2854       elsif Dynamic_Scope = Empty then
2855          return Empty;
2856
2857       elsif Ekind (Dynamic_Scope) = E_Subprogram_Body then
2858          return Corresponding_Spec (Parent (Parent (Dynamic_Scope)));
2859
2860       elsif Ekind (Dynamic_Scope) = E_Block
2861         or else Ekind (Dynamic_Scope) = E_Return_Statement
2862       then
2863          return Enclosing_Subprogram (Dynamic_Scope);
2864
2865       elsif Ekind (Dynamic_Scope) = E_Task_Type then
2866          return Get_Task_Body_Procedure (Dynamic_Scope);
2867
2868       elsif Ekind (Dynamic_Scope) = E_Limited_Private_Type
2869         and then Present (Full_View (Dynamic_Scope))
2870         and then Ekind (Full_View (Dynamic_Scope)) = E_Task_Type
2871       then
2872          return Get_Task_Body_Procedure (Full_View (Dynamic_Scope));
2873
2874       --  No body is generated if the protected operation is eliminated
2875
2876       elsif Convention (Dynamic_Scope) = Convention_Protected
2877         and then not Is_Eliminated (Dynamic_Scope)
2878         and then Present (Protected_Body_Subprogram (Dynamic_Scope))
2879       then
2880          return Protected_Body_Subprogram (Dynamic_Scope);
2881
2882       else
2883          return Dynamic_Scope;
2884       end if;
2885    end Enclosing_Subprogram;
2886
2887    ------------------------
2888    -- Ensure_Freeze_Node --
2889    ------------------------
2890
2891    procedure Ensure_Freeze_Node (E : Entity_Id) is
2892       FN : Node_Id;
2893
2894    begin
2895       if No (Freeze_Node (E)) then
2896          FN := Make_Freeze_Entity (Sloc (E));
2897          Set_Has_Delayed_Freeze (E);
2898          Set_Freeze_Node (E, FN);
2899          Set_Access_Types_To_Process (FN, No_Elist);
2900          Set_TSS_Elist (FN, No_Elist);
2901          Set_Entity (FN, E);
2902       end if;
2903    end Ensure_Freeze_Node;
2904
2905    ----------------
2906    -- Enter_Name --
2907    ----------------
2908
2909    procedure Enter_Name (Def_Id : Entity_Id) is
2910       C : constant Entity_Id := Current_Entity (Def_Id);
2911       E : constant Entity_Id := Current_Entity_In_Scope (Def_Id);
2912       S : constant Entity_Id := Current_Scope;
2913
2914    begin
2915       Generate_Definition (Def_Id);
2916
2917       --  Add new name to current scope declarations. Check for duplicate
2918       --  declaration, which may or may not be a genuine error.
2919
2920       if Present (E) then
2921
2922          --  Case of previous entity entered because of a missing declaration
2923          --  or else a bad subtype indication. Best is to use the new entity,
2924          --  and make the previous one invisible.
2925
2926          if Etype (E) = Any_Type then
2927             Set_Is_Immediately_Visible (E, False);
2928
2929          --  Case of renaming declaration constructed for package instances.
2930          --  if there is an explicit declaration with the same identifier,
2931          --  the renaming is not immediately visible any longer, but remains
2932          --  visible through selected component notation.
2933
2934          elsif Nkind (Parent (E)) = N_Package_Renaming_Declaration
2935            and then not Comes_From_Source (E)
2936          then
2937             Set_Is_Immediately_Visible (E, False);
2938
2939          --  The new entity may be the package renaming, which has the same
2940          --  same name as a generic formal which has been seen already.
2941
2942          elsif Nkind (Parent (Def_Id)) = N_Package_Renaming_Declaration
2943             and then not Comes_From_Source (Def_Id)
2944          then
2945             Set_Is_Immediately_Visible (E, False);
2946
2947          --  For a fat pointer corresponding to a remote access to subprogram,
2948          --  we use the same identifier as the RAS type, so that the proper
2949          --  name appears in the stub. This type is only retrieved through
2950          --  the RAS type and never by visibility, and is not added to the
2951          --  visibility list (see below).
2952
2953          elsif Nkind (Parent (Def_Id)) = N_Full_Type_Declaration
2954            and then Present (Corresponding_Remote_Type (Def_Id))
2955          then
2956             null;
2957
2958          --  A controller component for a type extension overrides the
2959          --  inherited component.
2960
2961          elsif Chars (E) = Name_uController then
2962             null;
2963
2964          --  Case of an implicit operation or derived literal. The new entity
2965          --  hides the implicit one,  which is removed from all visibility,
2966          --  i.e. the entity list of its scope, and homonym chain of its name.
2967
2968          elsif (Is_Overloadable (E) and then Is_Inherited_Operation (E))
2969            or else Is_Internal (E)
2970          then
2971             declare
2972                Prev     : Entity_Id;
2973                Prev_Vis : Entity_Id;
2974                Decl     : constant Node_Id := Parent (E);
2975
2976             begin
2977                --  If E is an implicit declaration, it cannot be the first
2978                --  entity in the scope.
2979
2980                Prev := First_Entity (Current_Scope);
2981                while Present (Prev)
2982                  and then Next_Entity (Prev) /= E
2983                loop
2984                   Next_Entity (Prev);
2985                end loop;
2986
2987                if No (Prev) then
2988
2989                   --  If E is not on the entity chain of the current scope,
2990                   --  it is an implicit declaration in the generic formal
2991                   --  part of a generic subprogram. When analyzing the body,
2992                   --  the generic formals are visible but not on the entity
2993                   --  chain of the subprogram. The new entity will become
2994                   --  the visible one in the body.
2995
2996                   pragma Assert
2997                     (Nkind (Parent (Decl)) = N_Generic_Subprogram_Declaration);
2998                   null;
2999
3000                else
3001                   Set_Next_Entity (Prev, Next_Entity (E));
3002
3003                   if No (Next_Entity (Prev)) then
3004                      Set_Last_Entity (Current_Scope, Prev);
3005                   end if;
3006
3007                   if E = Current_Entity (E) then
3008                      Prev_Vis := Empty;
3009
3010                   else
3011                      Prev_Vis := Current_Entity (E);
3012                      while Homonym (Prev_Vis) /= E loop
3013                         Prev_Vis := Homonym (Prev_Vis);
3014                      end loop;
3015                   end if;
3016
3017                   if Present (Prev_Vis)  then
3018
3019                      --  Skip E in the visibility chain
3020
3021                      Set_Homonym (Prev_Vis, Homonym (E));
3022
3023                   else
3024                      Set_Name_Entity_Id (Chars (E), Homonym (E));
3025                   end if;
3026                end if;
3027             end;
3028
3029          --  This section of code could use a comment ???
3030
3031          elsif Present (Etype (E))
3032            and then Is_Concurrent_Type (Etype (E))
3033            and then E = Def_Id
3034          then
3035             return;
3036
3037          --  If the homograph is a protected component renaming, it should not
3038          --  be hiding the current entity. Such renamings are treated as weak
3039          --  declarations.
3040
3041          elsif Is_Prival (E) then
3042             Set_Is_Immediately_Visible (E, False);
3043
3044          --  In this case the current entity is a protected component renaming.
3045          --  Perform minimal decoration by setting the scope and return since
3046          --  the prival should not be hiding other visible entities.
3047
3048          elsif Is_Prival (Def_Id) then
3049             Set_Scope (Def_Id, Current_Scope);
3050             return;
3051
3052          --  Analogous to privals, the discriminal generated for an entry index
3053          --  parameter acts as a weak declaration. Perform minimal decoration
3054          --  to avoid bogus errors.
3055
3056          elsif Is_Discriminal (Def_Id)
3057            and then Ekind (Discriminal_Link (Def_Id)) = E_Entry_Index_Parameter
3058          then
3059             Set_Scope (Def_Id, Current_Scope);
3060             return;
3061
3062          --  In the body or private part of an instance, a type extension may
3063          --  introduce a component with the same name as that of an actual. The
3064          --  legality rule is not enforced, but the semantics of the full type
3065          --  with two components of same name are not clear at this point???
3066
3067          elsif In_Instance_Not_Visible then
3068             null;
3069
3070          --  When compiling a package body, some child units may have become
3071          --  visible. They cannot conflict with local entities that hide them.
3072
3073          elsif Is_Child_Unit (E)
3074            and then In_Open_Scopes (Scope (E))
3075            and then not Is_Immediately_Visible (E)
3076          then
3077             null;
3078
3079          --  Conversely, with front-end inlining we may compile the parent body
3080          --  first, and a child unit subsequently. The context is now the
3081          --  parent spec, and body entities are not visible.
3082
3083          elsif Is_Child_Unit (Def_Id)
3084            and then Is_Package_Body_Entity (E)
3085            and then not In_Package_Body (Current_Scope)
3086          then
3087             null;
3088
3089          --  Case of genuine duplicate declaration
3090
3091          else
3092             Error_Msg_Sloc := Sloc (E);
3093
3094             --  If the previous declaration is an incomplete type declaration
3095             --  this may be an attempt to complete it with a private type. The
3096             --  following avoids confusing cascaded errors.
3097
3098             if Nkind (Parent (E)) = N_Incomplete_Type_Declaration
3099               and then Nkind (Parent (Def_Id)) = N_Private_Type_Declaration
3100             then
3101                Error_Msg_N
3102                  ("incomplete type cannot be completed with a private " &
3103                   "declaration", Parent (Def_Id));
3104                Set_Is_Immediately_Visible (E, False);
3105                Set_Full_View (E, Def_Id);
3106
3107             --  An inherited component of a record conflicts with a new
3108             --  discriminant. The discriminant is inserted first in the scope,
3109             --  but the error should be posted on it, not on the component.
3110
3111             elsif Ekind (E) = E_Discriminant
3112               and then Present (Scope (Def_Id))
3113               and then Scope (Def_Id) /= Current_Scope
3114             then
3115                Error_Msg_Sloc := Sloc (Def_Id);
3116                Error_Msg_N ("& conflicts with declaration#", E);
3117                return;
3118
3119             --  If the name of the unit appears in its own context clause, a
3120             --  dummy package with the name has already been created, and the
3121             --  error emitted. Try to continue quietly.
3122
3123             elsif Error_Posted (E)
3124               and then Sloc (E) = No_Location
3125               and then Nkind (Parent (E)) = N_Package_Specification
3126               and then Current_Scope = Standard_Standard
3127             then
3128                Set_Scope (Def_Id, Current_Scope);
3129                return;
3130
3131             else
3132                Error_Msg_N ("& conflicts with declaration#", Def_Id);
3133
3134                --  Avoid cascaded messages with duplicate components in
3135                --  derived types.
3136
3137                if Ekind_In (E, E_Component, E_Discriminant) then
3138                   return;
3139                end if;
3140             end if;
3141
3142             if Nkind (Parent (Parent (Def_Id))) =
3143                 N_Generic_Subprogram_Declaration
3144               and then Def_Id =
3145                 Defining_Entity (Specification (Parent (Parent (Def_Id))))
3146             then
3147                Error_Msg_N ("\generic units cannot be overloaded", Def_Id);
3148             end if;
3149
3150             --  If entity is in standard, then we are in trouble, because it
3151             --  means that we have a library package with a duplicated name.
3152             --  That's hard to recover from, so abort!
3153
3154             if S = Standard_Standard then
3155                raise Unrecoverable_Error;
3156
3157             --  Otherwise we continue with the declaration. Having two
3158             --  identical declarations should not cause us too much trouble!
3159
3160             else
3161                null;
3162             end if;
3163          end if;
3164       end if;
3165
3166       --  If we fall through, declaration is OK, at least OK enough to continue
3167
3168       --  If Def_Id is a discriminant or a record component we are in the midst
3169       --  of inheriting components in a derived record definition. Preserve
3170       --  their Ekind and Etype.
3171
3172       if Ekind_In (Def_Id, E_Discriminant, E_Component) then
3173          null;
3174
3175       --  If a type is already set, leave it alone (happens when a type
3176       --  declaration is reanalyzed following a call to the optimizer).
3177
3178       elsif Present (Etype (Def_Id)) then
3179          null;
3180
3181       --  Otherwise, the kind E_Void insures that premature uses of the entity
3182       --  will be detected. Any_Type insures that no cascaded errors will occur
3183
3184       else
3185          Set_Ekind (Def_Id, E_Void);
3186          Set_Etype (Def_Id, Any_Type);
3187       end if;
3188
3189       --  Inherited discriminants and components in derived record types are
3190       --  immediately visible. Itypes are not.
3191
3192       if Ekind_In (Def_Id, E_Discriminant, E_Component)
3193         or else (No (Corresponding_Remote_Type (Def_Id))
3194                  and then not Is_Itype (Def_Id))
3195       then
3196          Set_Is_Immediately_Visible (Def_Id);
3197          Set_Current_Entity         (Def_Id);
3198       end if;
3199
3200       Set_Homonym       (Def_Id, C);
3201       Append_Entity     (Def_Id, S);
3202       Set_Public_Status (Def_Id);
3203
3204       --  Declaring a homonym is not allowed in SPARK or ALFA ...
3205
3206       if Present (C)
3207
3208         --  ... unless the new declaration is in a subprogram, and the visible
3209         --  declaration is a variable declaration or a parameter specification
3210         --  outside that subprogram.
3211
3212         and then not
3213           (Nkind_In (Parent (Parent (Def_Id)), N_Subprogram_Body,
3214                                                N_Function_Specification,
3215                                                N_Procedure_Specification)
3216            and then
3217              Nkind_In (Parent (C), N_Object_Declaration,
3218                                    N_Parameter_Specification))
3219
3220         --  ... or the new declaration is in a package, and the visible
3221         --  declaration occurs outside that package.
3222
3223         and then not
3224           Nkind_In (Parent (Parent (Def_Id)), N_Package_Specification,
3225                                               N_Package_Body)
3226
3227         --  ... or the new declaration is a component declaration in a record
3228         --  type definition.
3229
3230         and then Nkind (Parent (Def_Id)) /= N_Component_Declaration
3231
3232         --  Don't issue error for non-source entities
3233
3234         and then Comes_From_Source (Def_Id)
3235         and then Comes_From_Source (C)
3236       then
3237          Error_Msg_Sloc := Sloc (C);
3238          Check_Formal_Restriction ("redeclaration of identifier &#", Def_Id);
3239       end if;
3240
3241       --  Warn if new entity hides an old one
3242
3243       if Warn_On_Hiding and then Present (C)
3244
3245          --  Don't warn for record components since they always have a well
3246          --  defined scope which does not confuse other uses. Note that in
3247          --  some cases, Ekind has not been set yet.
3248
3249          and then Ekind (C) /= E_Component
3250          and then Ekind (C) /= E_Discriminant
3251          and then Nkind (Parent (C)) /= N_Component_Declaration
3252          and then Ekind (Def_Id) /= E_Component
3253          and then Ekind (Def_Id) /= E_Discriminant
3254          and then Nkind (Parent (Def_Id)) /= N_Component_Declaration
3255
3256          --  Don't warn for one character variables. It is too common to use
3257          --  such variables as locals and will just cause too many false hits.
3258
3259          and then Length_Of_Name (Chars (C)) /= 1
3260
3261          --  Don't warn for non-source entities
3262
3263          and then Comes_From_Source (C)
3264          and then Comes_From_Source (Def_Id)
3265
3266          --  Don't warn unless entity in question is in extended main source
3267
3268          and then In_Extended_Main_Source_Unit (Def_Id)
3269
3270          --  Finally, the hidden entity must be either immediately visible or
3271          --  use visible (i.e. from a used package).
3272
3273          and then
3274            (Is_Immediately_Visible (C)
3275               or else
3276             Is_Potentially_Use_Visible (C))
3277       then
3278          Error_Msg_Sloc := Sloc (C);
3279          Error_Msg_N ("declaration hides &#?", Def_Id);
3280       end if;
3281    end Enter_Name;
3282
3283    --------------------------
3284    -- Explain_Limited_Type --
3285    --------------------------
3286
3287    procedure Explain_Limited_Type (T : Entity_Id; N : Node_Id) is
3288       C : Entity_Id;
3289
3290    begin
3291       --  For array, component type must be limited
3292
3293       if Is_Array_Type (T) then
3294          Error_Msg_Node_2 := T;
3295          Error_Msg_NE
3296            ("\component type& of type& is limited", N, Component_Type (T));
3297          Explain_Limited_Type (Component_Type (T), N);
3298
3299       elsif Is_Record_Type (T) then
3300
3301          --  No need for extra messages if explicit limited record
3302
3303          if Is_Limited_Record (Base_Type (T)) then
3304             return;
3305          end if;
3306
3307          --  Otherwise find a limited component. Check only components that
3308          --  come from source, or inherited components that appear in the
3309          --  source of the ancestor.
3310
3311          C := First_Component (T);
3312          while Present (C) loop
3313             if Is_Limited_Type (Etype (C))
3314               and then
3315                 (Comes_From_Source (C)
3316                    or else
3317                      (Present (Original_Record_Component (C))
3318                        and then
3319                          Comes_From_Source (Original_Record_Component (C))))
3320             then
3321                Error_Msg_Node_2 := T;
3322                Error_Msg_NE ("\component& of type& has limited type", N, C);
3323                Explain_Limited_Type (Etype (C), N);
3324                return;
3325             end if;
3326
3327             Next_Component (C);
3328          end loop;
3329
3330          --  The type may be declared explicitly limited, even if no component
3331          --  of it is limited, in which case we fall out of the loop.
3332          return;
3333       end if;
3334    end Explain_Limited_Type;
3335
3336    -----------------
3337    -- Find_Actual --
3338    -----------------
3339
3340    procedure Find_Actual
3341      (N        : Node_Id;
3342       Formal   : out Entity_Id;
3343       Call     : out Node_Id)
3344    is
3345       Parnt  : constant Node_Id := Parent (N);
3346       Actual : Node_Id;
3347
3348    begin
3349       if (Nkind (Parnt) = N_Indexed_Component
3350             or else
3351           Nkind (Parnt) = N_Selected_Component)
3352         and then N = Prefix (Parnt)
3353       then
3354          Find_Actual (Parnt, Formal, Call);
3355          return;
3356
3357       elsif Nkind (Parnt) = N_Parameter_Association
3358         and then N = Explicit_Actual_Parameter (Parnt)
3359       then
3360          Call := Parent (Parnt);
3361
3362       elsif Nkind (Parnt) = N_Procedure_Call_Statement then
3363          Call := Parnt;
3364
3365       else
3366          Formal := Empty;
3367          Call   := Empty;
3368          return;
3369       end if;
3370
3371       --  If we have a call to a subprogram look for the parameter. Note that
3372       --  we exclude overloaded calls, since we don't know enough to be sure
3373       --  of giving the right answer in this case.
3374
3375       if Is_Entity_Name (Name (Call))
3376         and then Present (Entity (Name (Call)))
3377         and then Is_Overloadable (Entity (Name (Call)))
3378         and then not Is_Overloaded (Name (Call))
3379       then
3380          --  Fall here if we are definitely a parameter
3381
3382          Actual := First_Actual (Call);
3383          Formal := First_Formal (Entity (Name (Call)));
3384          while Present (Formal) and then Present (Actual) loop
3385             if Actual = N then
3386                return;
3387             else
3388                Actual := Next_Actual (Actual);
3389                Formal := Next_Formal (Formal);
3390             end if;
3391          end loop;
3392       end if;
3393
3394       --  Fall through here if we did not find matching actual
3395
3396       Formal := Empty;
3397       Call   := Empty;
3398    end Find_Actual;
3399
3400    ---------------------------
3401    -- Find_Body_Discriminal --
3402    ---------------------------
3403
3404    function Find_Body_Discriminal
3405      (Spec_Discriminant : Entity_Id) return Entity_Id
3406    is
3407       pragma Assert (Is_Concurrent_Record_Type (Scope (Spec_Discriminant)));
3408
3409       Tsk  : constant Entity_Id :=
3410                Corresponding_Concurrent_Type (Scope (Spec_Discriminant));
3411       Disc : Entity_Id;
3412
3413    begin
3414       --  Find discriminant of original concurrent type, and use its current
3415       --  discriminal, which is the renaming within the task/protected body.
3416
3417       Disc := First_Discriminant (Tsk);
3418       while Present (Disc) loop
3419          if Chars (Disc) = Chars (Spec_Discriminant) then
3420             return Discriminal (Disc);
3421          end if;
3422
3423          Next_Discriminant (Disc);
3424       end loop;
3425
3426       --  That loop should always succeed in finding a matching entry and
3427       --  returning. Fatal error if not.
3428
3429       raise Program_Error;
3430    end Find_Body_Discriminal;
3431
3432    -------------------------------------
3433    -- Find_Corresponding_Discriminant --
3434    -------------------------------------
3435
3436    function Find_Corresponding_Discriminant
3437      (Id  : Node_Id;
3438       Typ : Entity_Id) return Entity_Id
3439    is
3440       Par_Disc : Entity_Id;
3441       Old_Disc : Entity_Id;
3442       New_Disc : Entity_Id;
3443
3444    begin
3445       Par_Disc := Original_Record_Component (Original_Discriminant (Id));
3446
3447       --  The original type may currently be private, and the discriminant
3448       --  only appear on its full view.
3449
3450       if Is_Private_Type (Scope (Par_Disc))
3451         and then not Has_Discriminants (Scope (Par_Disc))
3452         and then Present (Full_View (Scope (Par_Disc)))
3453       then
3454          Old_Disc := First_Discriminant (Full_View (Scope (Par_Disc)));
3455       else
3456          Old_Disc := First_Discriminant (Scope (Par_Disc));
3457       end if;
3458
3459       if Is_Class_Wide_Type (Typ) then
3460          New_Disc := First_Discriminant (Root_Type (Typ));
3461       else
3462          New_Disc := First_Discriminant (Typ);
3463       end if;
3464
3465       while Present (Old_Disc) and then Present (New_Disc) loop
3466          if Old_Disc = Par_Disc  then
3467             return New_Disc;
3468          else
3469             Next_Discriminant (Old_Disc);
3470             Next_Discriminant (New_Disc);
3471          end if;
3472       end loop;
3473
3474       --  Should always find it
3475
3476       raise Program_Error;
3477    end Find_Corresponding_Discriminant;
3478
3479    --------------------------
3480    -- Find_Overlaid_Entity --
3481    --------------------------
3482
3483    procedure Find_Overlaid_Entity
3484      (N   : Node_Id;
3485       Ent : out Entity_Id;
3486       Off : out Boolean)
3487    is
3488       Expr : Node_Id;
3489
3490    begin
3491       --  We are looking for one of the two following forms:
3492
3493       --    for X'Address use Y'Address
3494
3495       --  or
3496
3497       --    Const : constant Address := expr;
3498       --    ...
3499       --    for X'Address use Const;
3500
3501       --  In the second case, the expr is either Y'Address, or recursively a
3502       --  constant that eventually references Y'Address.
3503
3504       Ent := Empty;
3505       Off := False;
3506
3507       if Nkind (N) = N_Attribute_Definition_Clause
3508         and then Chars (N) = Name_Address
3509       then
3510          Expr := Expression (N);
3511
3512          --  This loop checks the form of the expression for Y'Address,
3513          --  using recursion to deal with intermediate constants.
3514
3515          loop
3516             --  Check for Y'Address
3517
3518             if Nkind (Expr) = N_Attribute_Reference
3519               and then Attribute_Name (Expr) = Name_Address
3520             then
3521                Expr := Prefix (Expr);
3522                exit;
3523
3524                --  Check for Const where Const is a constant entity
3525
3526             elsif Is_Entity_Name (Expr)
3527               and then Ekind (Entity (Expr)) = E_Constant
3528             then
3529                Expr := Constant_Value (Entity (Expr));
3530
3531             --  Anything else does not need checking
3532
3533             else
3534                return;
3535             end if;
3536          end loop;
3537
3538          --  This loop checks the form of the prefix for an entity,
3539          --  using recursion to deal with intermediate components.
3540
3541          loop
3542             --  Check for Y where Y is an entity
3543
3544             if Is_Entity_Name (Expr) then
3545                Ent := Entity (Expr);
3546                return;
3547
3548             --  Check for components
3549
3550             elsif
3551                Nkind_In (Expr, N_Selected_Component, N_Indexed_Component) then
3552
3553                Expr := Prefix (Expr);
3554                Off := True;
3555
3556             --  Anything else does not need checking
3557
3558             else
3559                return;
3560             end if;
3561          end loop;
3562       end if;
3563    end Find_Overlaid_Entity;
3564
3565    -------------------------
3566    -- Find_Parameter_Type --
3567    -------------------------
3568
3569    function Find_Parameter_Type (Param : Node_Id) return Entity_Id is
3570    begin
3571       if Nkind (Param) /= N_Parameter_Specification then
3572          return Empty;
3573
3574       --  For an access parameter, obtain the type from the formal entity
3575       --  itself, because access to subprogram nodes do not carry a type.
3576       --  Shouldn't we always use the formal entity ???
3577
3578       elsif Nkind (Parameter_Type (Param)) = N_Access_Definition then
3579          return Etype (Defining_Identifier (Param));
3580
3581       else
3582          return Etype (Parameter_Type (Param));
3583       end if;
3584    end Find_Parameter_Type;
3585
3586    -----------------------------
3587    -- Find_Static_Alternative --
3588    -----------------------------
3589
3590    function Find_Static_Alternative (N : Node_Id) return Node_Id is
3591       Expr   : constant Node_Id := Expression (N);
3592       Val    : constant Uint    := Expr_Value (Expr);
3593       Alt    : Node_Id;
3594       Choice : Node_Id;
3595
3596    begin
3597       Alt := First (Alternatives (N));
3598
3599       Search : loop
3600          if Nkind (Alt) /= N_Pragma then
3601             Choice := First (Discrete_Choices (Alt));
3602             while Present (Choice) loop
3603
3604                --  Others choice, always matches
3605
3606                if Nkind (Choice) = N_Others_Choice then
3607                   exit Search;
3608
3609                --  Range, check if value is in the range
3610
3611                elsif Nkind (Choice) = N_Range then
3612                   exit Search when
3613                     Val >= Expr_Value (Low_Bound (Choice))
3614                       and then
3615                     Val <= Expr_Value (High_Bound (Choice));
3616
3617                --  Choice is a subtype name. Note that we know it must
3618                --  be a static subtype, since otherwise it would have
3619                --  been diagnosed as illegal.
3620
3621                elsif Is_Entity_Name (Choice)
3622                  and then Is_Type (Entity (Choice))
3623                then
3624                   exit Search when Is_In_Range (Expr, Etype (Choice),
3625                                                 Assume_Valid => False);
3626
3627                --  Choice is a subtype indication
3628
3629                elsif Nkind (Choice) = N_Subtype_Indication then
3630                   declare
3631                      C : constant Node_Id := Constraint (Choice);
3632                      R : constant Node_Id := Range_Expression (C);
3633
3634                   begin
3635                      exit Search when
3636                        Val >= Expr_Value (Low_Bound (R))
3637                          and then
3638                        Val <= Expr_Value (High_Bound (R));
3639                   end;
3640
3641                --  Choice is a simple expression
3642
3643                else
3644                   exit Search when Val = Expr_Value (Choice);
3645                end if;
3646
3647                Next (Choice);
3648             end loop;
3649          end if;
3650
3651          Next (Alt);
3652          pragma Assert (Present (Alt));
3653       end loop Search;
3654
3655       --  The above loop *must* terminate by finding a match, since
3656       --  we know the case statement is valid, and the value of the
3657       --  expression is known at compile time. When we fall out of
3658       --  the loop, Alt points to the alternative that we know will
3659       --  be selected at run time.
3660
3661       return Alt;
3662    end Find_Static_Alternative;
3663
3664    ------------------
3665    -- First_Actual --
3666    ------------------
3667
3668    function First_Actual (Node : Node_Id) return Node_Id is
3669       N : Node_Id;
3670
3671    begin
3672       if No (Parameter_Associations (Node)) then
3673          return Empty;
3674       end if;
3675
3676       N := First (Parameter_Associations (Node));
3677
3678       if Nkind (N) = N_Parameter_Association then
3679          return First_Named_Actual (Node);
3680       else
3681          return N;
3682       end if;
3683    end First_Actual;
3684
3685    -----------------------
3686    -- Gather_Components --
3687    -----------------------
3688
3689    procedure Gather_Components
3690      (Typ           : Entity_Id;
3691       Comp_List     : Node_Id;
3692       Governed_By   : List_Id;
3693       Into          : Elist_Id;
3694       Report_Errors : out Boolean)
3695    is
3696       Assoc           : Node_Id;
3697       Variant         : Node_Id;
3698       Discrete_Choice : Node_Id;
3699       Comp_Item       : Node_Id;
3700
3701       Discrim       : Entity_Id;
3702       Discrim_Name  : Node_Id;
3703       Discrim_Value : Node_Id;
3704
3705    begin
3706       Report_Errors := False;
3707
3708       if No (Comp_List) or else Null_Present (Comp_List) then
3709          return;
3710
3711       elsif Present (Component_Items (Comp_List)) then
3712          Comp_Item := First (Component_Items (Comp_List));
3713
3714       else
3715          Comp_Item := Empty;
3716       end if;
3717
3718       while Present (Comp_Item) loop
3719
3720          --  Skip the tag of a tagged record, the interface tags, as well
3721          --  as all items that are not user components (anonymous types,
3722          --  rep clauses, Parent field, controller field).
3723
3724          if Nkind (Comp_Item) = N_Component_Declaration then
3725             declare
3726                Comp : constant Entity_Id := Defining_Identifier (Comp_Item);
3727             begin
3728                if not Is_Tag (Comp)
3729                  and then Chars (Comp) /= Name_uParent
3730                  and then Chars (Comp) /= Name_uController
3731                then
3732                   Append_Elmt (Comp, Into);
3733                end if;
3734             end;
3735          end if;
3736
3737          Next (Comp_Item);
3738       end loop;
3739
3740       if No (Variant_Part (Comp_List)) then
3741          return;
3742       else
3743          Discrim_Name := Name (Variant_Part (Comp_List));
3744          Variant := First_Non_Pragma (Variants (Variant_Part (Comp_List)));
3745       end if;
3746
3747       --  Look for the discriminant that governs this variant part.
3748       --  The discriminant *must* be in the Governed_By List
3749
3750       Assoc := First (Governed_By);
3751       Find_Constraint : loop
3752          Discrim := First (Choices (Assoc));
3753          exit Find_Constraint when Chars (Discrim_Name) = Chars (Discrim)
3754            or else (Present (Corresponding_Discriminant (Entity (Discrim)))
3755                       and then
3756                     Chars (Corresponding_Discriminant (Entity (Discrim)))
3757                          = Chars  (Discrim_Name))
3758            or else Chars (Original_Record_Component (Entity (Discrim)))
3759                          = Chars (Discrim_Name);
3760
3761          if No (Next (Assoc)) then
3762             if not Is_Constrained (Typ)
3763               and then Is_Derived_Type (Typ)
3764               and then Present (Stored_Constraint (Typ))
3765             then
3766                --  If the type is a tagged type with inherited discriminants,
3767                --  use the stored constraint on the parent in order to find
3768                --  the values of discriminants that are otherwise hidden by an
3769                --  explicit constraint. Renamed discriminants are handled in
3770                --  the code above.
3771
3772                --  If several parent discriminants are renamed by a single
3773                --  discriminant of the derived type, the call to obtain the
3774                --  Corresponding_Discriminant field only retrieves the last
3775                --  of them. We recover the constraint on the others from the
3776                --  Stored_Constraint as well.
3777
3778                declare
3779                   D : Entity_Id;
3780                   C : Elmt_Id;
3781
3782                begin
3783                   D := First_Discriminant (Etype (Typ));
3784                   C := First_Elmt (Stored_Constraint (Typ));
3785                   while Present (D) and then Present (C) loop
3786                      if Chars (Discrim_Name) = Chars (D) then
3787                         if Is_Entity_Name (Node (C))
3788                           and then Entity (Node (C)) = Entity (Discrim)
3789                         then
3790                            --  D is renamed by Discrim, whose value is given in
3791                            --  Assoc.
3792
3793                            null;
3794
3795                         else
3796                            Assoc :=
3797                              Make_Component_Association (Sloc (Typ),
3798                                New_List
3799                                  (New_Occurrence_Of (D, Sloc (Typ))),
3800                                   Duplicate_Subexpr_No_Checks (Node (C)));
3801                         end if;
3802                         exit Find_Constraint;
3803                      end if;
3804
3805                      Next_Discriminant (D);
3806                      Next_Elmt (C);
3807                   end loop;
3808                end;
3809             end if;
3810          end if;
3811
3812          if No (Next (Assoc)) then
3813             Error_Msg_NE (" missing value for discriminant&",
3814               First (Governed_By), Discrim_Name);
3815             Report_Errors := True;
3816             return;
3817          end if;
3818
3819          Next (Assoc);
3820       end loop Find_Constraint;
3821
3822       Discrim_Value := Expression (Assoc);
3823
3824       if not Is_OK_Static_Expression (Discrim_Value) then
3825          Error_Msg_FE
3826            ("value for discriminant & must be static!",
3827             Discrim_Value, Discrim);
3828          Why_Not_Static (Discrim_Value);
3829          Report_Errors := True;
3830          return;
3831       end if;
3832
3833       Search_For_Discriminant_Value : declare
3834          Low  : Node_Id;
3835          High : Node_Id;
3836
3837          UI_High          : Uint;
3838          UI_Low           : Uint;
3839          UI_Discrim_Value : constant Uint := Expr_Value (Discrim_Value);
3840
3841       begin
3842          Find_Discrete_Value : while Present (Variant) loop
3843             Discrete_Choice := First (Discrete_Choices (Variant));
3844             while Present (Discrete_Choice) loop
3845
3846                exit Find_Discrete_Value when
3847                  Nkind (Discrete_Choice) = N_Others_Choice;
3848
3849                Get_Index_Bounds (Discrete_Choice, Low, High);
3850
3851                UI_Low  := Expr_Value (Low);
3852                UI_High := Expr_Value (High);
3853
3854                exit Find_Discrete_Value when
3855                  UI_Low <= UI_Discrim_Value
3856                    and then
3857                  UI_High >= UI_Discrim_Value;
3858
3859                Next (Discrete_Choice);
3860             end loop;
3861
3862             Next_Non_Pragma (Variant);
3863          end loop Find_Discrete_Value;
3864       end Search_For_Discriminant_Value;
3865
3866       if No (Variant) then
3867          Error_Msg_NE
3868            ("value of discriminant & is out of range", Discrim_Value, Discrim);
3869          Report_Errors := True;
3870          return;
3871       end  if;
3872
3873       --  If we have found the corresponding choice, recursively add its
3874       --  components to the Into list.
3875
3876       Gather_Components (Empty,
3877         Component_List (Variant), Governed_By, Into, Report_Errors);
3878    end Gather_Components;
3879
3880    ------------------------
3881    -- Get_Actual_Subtype --
3882    ------------------------
3883
3884    function Get_Actual_Subtype (N : Node_Id) return Entity_Id is
3885       Typ  : constant Entity_Id := Etype (N);
3886       Utyp : Entity_Id := Underlying_Type (Typ);
3887       Decl : Node_Id;
3888       Atyp : Entity_Id;
3889
3890    begin
3891       if No (Utyp) then
3892          Utyp := Typ;
3893       end if;
3894
3895       --  If what we have is an identifier that references a subprogram
3896       --  formal, or a variable or constant object, then we get the actual
3897       --  subtype from the referenced entity if one has been built.
3898
3899       if Nkind (N) = N_Identifier
3900         and then
3901           (Is_Formal (Entity (N))
3902             or else Ekind (Entity (N)) = E_Constant
3903             or else Ekind (Entity (N)) = E_Variable)
3904         and then Present (Actual_Subtype (Entity (N)))
3905       then
3906          return Actual_Subtype (Entity (N));
3907
3908       --  Actual subtype of unchecked union is always itself. We never need
3909       --  the "real" actual subtype. If we did, we couldn't get it anyway
3910       --  because the discriminant is not available. The restrictions on
3911       --  Unchecked_Union are designed to make sure that this is OK.
3912
3913       elsif Is_Unchecked_Union (Base_Type (Utyp)) then
3914          return Typ;
3915
3916       --  Here for the unconstrained case, we must find actual subtype
3917       --  No actual subtype is available, so we must build it on the fly.
3918
3919       --  Checking the type, not the underlying type, for constrainedness
3920       --  seems to be necessary. Maybe all the tests should be on the type???
3921
3922       elsif (not Is_Constrained (Typ))
3923            and then (Is_Array_Type (Utyp)
3924                       or else (Is_Record_Type (Utyp)
3925                                 and then Has_Discriminants (Utyp)))
3926            and then not Has_Unknown_Discriminants (Utyp)
3927            and then not (Ekind (Utyp) = E_String_Literal_Subtype)
3928       then
3929          --  Nothing to do if in spec expression (why not???)
3930
3931          if In_Spec_Expression then
3932             return Typ;
3933
3934          elsif Is_Private_Type (Typ)
3935            and then not Has_Discriminants (Typ)
3936          then
3937             --  If the type has no discriminants, there is no subtype to
3938             --  build, even if the underlying type is discriminated.
3939
3940             return Typ;
3941
3942          --  Else build the actual subtype
3943
3944          else
3945             Decl := Build_Actual_Subtype (Typ, N);
3946             Atyp := Defining_Identifier (Decl);
3947
3948             --  If Build_Actual_Subtype generated a new declaration then use it
3949
3950             if Atyp /= Typ then
3951
3952                --  The actual subtype is an Itype, so analyze the declaration,
3953                --  but do not attach it to the tree, to get the type defined.
3954
3955                Set_Parent (Decl, N);
3956                Set_Is_Itype (Atyp);
3957                Analyze (Decl, Suppress => All_Checks);
3958                Set_Associated_Node_For_Itype (Atyp, N);
3959                Set_Has_Delayed_Freeze (Atyp, False);
3960
3961                --  We need to freeze the actual subtype immediately. This is
3962                --  needed, because otherwise this Itype will not get frozen
3963                --  at all, and it is always safe to freeze on creation because
3964                --  any associated types must be frozen at this point.
3965
3966                Freeze_Itype (Atyp, N);
3967                return Atyp;
3968
3969             --  Otherwise we did not build a declaration, so return original
3970
3971             else
3972                return Typ;
3973             end if;
3974          end if;
3975
3976       --  For all remaining cases, the actual subtype is the same as
3977       --  the nominal type.
3978
3979       else
3980          return Typ;
3981       end if;
3982    end Get_Actual_Subtype;
3983
3984    -------------------------------------
3985    -- Get_Actual_Subtype_If_Available --
3986    -------------------------------------
3987
3988    function Get_Actual_Subtype_If_Available (N : Node_Id) return Entity_Id is
3989       Typ  : constant Entity_Id := Etype (N);
3990
3991    begin
3992       --  If what we have is an identifier that references a subprogram
3993       --  formal, or a variable or constant object, then we get the actual
3994       --  subtype from the referenced entity if one has been built.
3995
3996       if Nkind (N) = N_Identifier
3997         and then
3998           (Is_Formal (Entity (N))
3999             or else Ekind (Entity (N)) = E_Constant
4000             or else Ekind (Entity (N)) = E_Variable)
4001         and then Present (Actual_Subtype (Entity (N)))
4002       then
4003          return Actual_Subtype (Entity (N));
4004
4005       --  Otherwise the Etype of N is returned unchanged
4006
4007       else
4008          return Typ;
4009       end if;
4010    end Get_Actual_Subtype_If_Available;
4011
4012    -------------------------------
4013    -- Get_Default_External_Name --
4014    -------------------------------
4015
4016    function Get_Default_External_Name (E : Node_Or_Entity_Id) return Node_Id is
4017    begin
4018       Get_Decoded_Name_String (Chars (E));
4019
4020       if Opt.External_Name_Imp_Casing = Uppercase then
4021          Set_Casing (All_Upper_Case);
4022       else
4023          Set_Casing (All_Lower_Case);
4024       end if;
4025
4026       return
4027         Make_String_Literal (Sloc (E),
4028           Strval => String_From_Name_Buffer);
4029    end Get_Default_External_Name;
4030
4031    ---------------------------
4032    -- Get_Enum_Lit_From_Pos --
4033    ---------------------------
4034
4035    function Get_Enum_Lit_From_Pos
4036      (T   : Entity_Id;
4037       Pos : Uint;
4038       Loc : Source_Ptr) return Node_Id
4039    is
4040       Lit : Node_Id;
4041
4042    begin
4043       --  In the case where the literal is of type Character, Wide_Character
4044       --  or Wide_Wide_Character or of a type derived from them, there needs
4045       --  to be some special handling since there is no explicit chain of
4046       --  literals to search. Instead, an N_Character_Literal node is created
4047       --  with the appropriate Char_Code and Chars fields.
4048
4049       if Is_Standard_Character_Type (T) then
4050          Set_Character_Literal_Name (UI_To_CC (Pos));
4051          return
4052            Make_Character_Literal (Loc,
4053              Chars              => Name_Find,
4054              Char_Literal_Value => Pos);
4055
4056       --  For all other cases, we have a complete table of literals, and
4057       --  we simply iterate through the chain of literal until the one
4058       --  with the desired position value is found.
4059       --
4060
4061       else
4062          Lit := First_Literal (Base_Type (T));
4063          for J in 1 .. UI_To_Int (Pos) loop
4064             Next_Literal (Lit);
4065          end loop;
4066
4067          return New_Occurrence_Of (Lit, Loc);
4068       end if;
4069    end Get_Enum_Lit_From_Pos;
4070
4071    ------------------------
4072    -- Get_Generic_Entity --
4073    ------------------------
4074
4075    function Get_Generic_Entity (N : Node_Id) return Entity_Id is
4076       Ent : constant Entity_Id := Entity (Name (N));
4077    begin
4078       if Present (Renamed_Object (Ent)) then
4079          return Renamed_Object (Ent);
4080       else
4081          return Ent;
4082       end if;
4083    end Get_Generic_Entity;
4084
4085    ----------------------
4086    -- Get_Index_Bounds --
4087    ----------------------
4088
4089    procedure Get_Index_Bounds (N : Node_Id; L, H : out Node_Id) is
4090       Kind : constant Node_Kind := Nkind (N);
4091       R    : Node_Id;
4092
4093    begin
4094       if Kind = N_Range then
4095          L := Low_Bound (N);
4096          H := High_Bound (N);
4097
4098       elsif Kind = N_Subtype_Indication then
4099          R := Range_Expression (Constraint (N));
4100
4101          if R = Error then
4102             L := Error;
4103             H := Error;
4104             return;
4105
4106          else
4107             L := Low_Bound  (Range_Expression (Constraint (N)));
4108             H := High_Bound (Range_Expression (Constraint (N)));
4109          end if;
4110
4111       elsif Is_Entity_Name (N) and then Is_Type (Entity (N)) then
4112          if Error_Posted (Scalar_Range (Entity (N))) then
4113             L := Error;
4114             H := Error;
4115
4116          elsif Nkind (Scalar_Range (Entity (N))) = N_Subtype_Indication then
4117             Get_Index_Bounds (Scalar_Range (Entity (N)), L, H);
4118
4119          else
4120             L := Low_Bound  (Scalar_Range (Entity (N)));
4121             H := High_Bound (Scalar_Range (Entity (N)));
4122          end if;
4123
4124       else
4125          --  N is an expression, indicating a range with one value
4126
4127          L := N;
4128          H := N;
4129       end if;
4130    end Get_Index_Bounds;
4131
4132    ----------------------------------
4133    -- Get_Library_Unit_Name_string --
4134    ----------------------------------
4135
4136    procedure Get_Library_Unit_Name_String (Decl_Node : Node_Id) is
4137       Unit_Name_Id : constant Unit_Name_Type := Get_Unit_Name (Decl_Node);
4138
4139    begin
4140       Get_Unit_Name_String (Unit_Name_Id);
4141
4142       --  Remove seven last character (" (spec)" or " (body)")
4143
4144       Name_Len := Name_Len - 7;
4145       pragma Assert (Name_Buffer (Name_Len + 1) = ' ');
4146    end Get_Library_Unit_Name_String;
4147
4148    ------------------------
4149    -- Get_Name_Entity_Id --
4150    ------------------------
4151
4152    function Get_Name_Entity_Id (Id : Name_Id) return Entity_Id is
4153    begin
4154       return Entity_Id (Get_Name_Table_Info (Id));
4155    end Get_Name_Entity_Id;
4156
4157    -------------------
4158    -- Get_Pragma_Id --
4159    -------------------
4160
4161    function Get_Pragma_Id (N : Node_Id) return Pragma_Id is
4162    begin
4163       return Get_Pragma_Id (Pragma_Name (N));
4164    end Get_Pragma_Id;
4165
4166    ---------------------------
4167    -- Get_Referenced_Object --
4168    ---------------------------
4169
4170    function Get_Referenced_Object (N : Node_Id) return Node_Id is
4171       R : Node_Id;
4172
4173    begin
4174       R := N;
4175       while Is_Entity_Name (R)
4176         and then Present (Renamed_Object (Entity (R)))
4177       loop
4178          R := Renamed_Object (Entity (R));
4179       end loop;
4180
4181       return R;
4182    end Get_Referenced_Object;
4183
4184    ------------------------
4185    -- Get_Renamed_Entity --
4186    ------------------------
4187
4188    function Get_Renamed_Entity (E : Entity_Id) return Entity_Id is
4189       R : Entity_Id;
4190
4191    begin
4192       R := E;
4193       while Present (Renamed_Entity (R)) loop
4194          R := Renamed_Entity (R);
4195       end loop;
4196
4197       return R;
4198    end Get_Renamed_Entity;
4199
4200    -------------------------
4201    -- Get_Subprogram_Body --
4202    -------------------------
4203
4204    function Get_Subprogram_Body (E : Entity_Id) return Node_Id is
4205       Decl : Node_Id;
4206
4207    begin
4208       Decl := Unit_Declaration_Node (E);
4209
4210       if Nkind (Decl) = N_Subprogram_Body then
4211          return Decl;
4212
4213       --  The below comment is bad, because it is possible for
4214       --  Nkind (Decl) to be an N_Subprogram_Body_Stub ???
4215
4216       else           --  Nkind (Decl) = N_Subprogram_Declaration
4217
4218          if Present (Corresponding_Body (Decl)) then
4219             return Unit_Declaration_Node (Corresponding_Body (Decl));
4220
4221          --  Imported subprogram case
4222
4223          else
4224             return Empty;
4225          end if;
4226       end if;
4227    end Get_Subprogram_Body;
4228
4229    ---------------------------
4230    -- Get_Subprogram_Entity --
4231    ---------------------------
4232
4233    function Get_Subprogram_Entity (Nod : Node_Id) return Entity_Id is
4234       Nam  : Node_Id;
4235       Proc : Entity_Id;
4236
4237    begin
4238       if Nkind (Nod) = N_Accept_Statement then
4239          Nam := Entry_Direct_Name (Nod);
4240
4241       --  For an entry call, the prefix of the call is a selected component.
4242       --  Need additional code for internal calls ???
4243
4244       elsif Nkind (Nod) = N_Entry_Call_Statement then
4245          if Nkind (Name (Nod)) = N_Selected_Component then
4246             Nam := Entity (Selector_Name (Name (Nod)));
4247          else
4248             Nam := Empty;
4249          end if;
4250
4251       else
4252          Nam := Name (Nod);
4253       end if;
4254
4255       if Nkind (Nam) = N_Explicit_Dereference then
4256          Proc := Etype (Prefix (Nam));
4257       elsif Is_Entity_Name (Nam) then
4258          Proc := Entity (Nam);
4259       else
4260          return Empty;
4261       end if;
4262
4263       if Is_Object (Proc) then
4264          Proc := Etype (Proc);
4265       end if;
4266
4267       if Ekind (Proc) = E_Access_Subprogram_Type then
4268          Proc := Directly_Designated_Type (Proc);
4269       end if;
4270
4271       if not Is_Subprogram (Proc)
4272         and then Ekind (Proc) /= E_Subprogram_Type
4273       then
4274          return Empty;
4275       else
4276          return Proc;
4277       end if;
4278    end Get_Subprogram_Entity;
4279
4280    -----------------------------
4281    -- Get_Task_Body_Procedure --
4282    -----------------------------
4283
4284    function Get_Task_Body_Procedure (E : Entity_Id) return Node_Id is
4285    begin
4286       --  Note: A task type may be the completion of a private type with
4287       --  discriminants. When performing elaboration checks on a task
4288       --  declaration, the current view of the type may be the private one,
4289       --  and the procedure that holds the body of the task is held in its
4290       --  underlying type.
4291
4292       --  This is an odd function, why not have Task_Body_Procedure do
4293       --  the following digging???
4294
4295       return Task_Body_Procedure (Underlying_Type (Root_Type (E)));
4296    end Get_Task_Body_Procedure;
4297
4298    -----------------------
4299    -- Has_Access_Values --
4300    -----------------------
4301
4302    function Has_Access_Values (T : Entity_Id) return Boolean is
4303       Typ : constant Entity_Id := Underlying_Type (T);
4304
4305    begin
4306       --  Case of a private type which is not completed yet. This can only
4307       --  happen in the case of a generic format type appearing directly, or
4308       --  as a component of the type to which this function is being applied
4309       --  at the top level. Return False in this case, since we certainly do
4310       --  not know that the type contains access types.
4311
4312       if No (Typ) then
4313          return False;
4314
4315       elsif Is_Access_Type (Typ) then
4316          return True;
4317
4318       elsif Is_Array_Type (Typ) then
4319          return Has_Access_Values (Component_Type (Typ));
4320
4321       elsif Is_Record_Type (Typ) then
4322          declare
4323             Comp : Entity_Id;
4324
4325          begin
4326             --  Loop to Check components
4327
4328             Comp := First_Component_Or_Discriminant (Typ);
4329             while Present (Comp) loop
4330
4331                --  Check for access component, tag field does not count, even
4332                --  though it is implemented internally using an access type.
4333
4334                if Has_Access_Values (Etype (Comp))
4335                  and then Chars (Comp) /= Name_uTag
4336                then
4337                   return True;
4338                end if;
4339
4340                Next_Component_Or_Discriminant (Comp);
4341             end loop;
4342          end;
4343
4344          return False;
4345
4346       else
4347          return False;
4348       end if;
4349    end Has_Access_Values;
4350
4351    ------------------------------
4352    -- Has_Compatible_Alignment --
4353    ------------------------------
4354
4355    function Has_Compatible_Alignment
4356      (Obj  : Entity_Id;
4357       Expr : Node_Id) return Alignment_Result
4358    is
4359       function Has_Compatible_Alignment_Internal
4360         (Obj     : Entity_Id;
4361          Expr    : Node_Id;
4362          Default : Alignment_Result) return Alignment_Result;
4363       --  This is the internal recursive function that actually does the work.
4364       --  There is one additional parameter, which says what the result should
4365       --  be if no alignment information is found, and there is no definite
4366       --  indication of compatible alignments. At the outer level, this is set
4367       --  to Unknown, but for internal recursive calls in the case where types
4368       --  are known to be correct, it is set to Known_Compatible.
4369
4370       ---------------------------------------
4371       -- Has_Compatible_Alignment_Internal --
4372       ---------------------------------------
4373
4374       function Has_Compatible_Alignment_Internal
4375         (Obj     : Entity_Id;
4376          Expr    : Node_Id;
4377          Default : Alignment_Result) return Alignment_Result
4378       is
4379          Result : Alignment_Result := Known_Compatible;
4380          --  Holds the current status of the result. Note that once a value of
4381          --  Known_Incompatible is set, it is sticky and does not get changed
4382          --  to Unknown (the value in Result only gets worse as we go along,
4383          --  never better).
4384
4385          Offs : Uint := No_Uint;
4386          --  Set to a factor of the offset from the base object when Expr is a
4387          --  selected or indexed component, based on Component_Bit_Offset and
4388          --  Component_Size respectively. A negative value is used to represent
4389          --  a value which is not known at compile time.
4390
4391          procedure Check_Prefix;
4392          --  Checks the prefix recursively in the case where the expression
4393          --  is an indexed or selected component.
4394
4395          procedure Set_Result (R : Alignment_Result);
4396          --  If R represents a worse outcome (unknown instead of known
4397          --  compatible, or known incompatible), then set Result to R.
4398
4399          ------------------
4400          -- Check_Prefix --
4401          ------------------
4402
4403          procedure Check_Prefix is
4404          begin
4405             --  The subtlety here is that in doing a recursive call to check
4406             --  the prefix, we have to decide what to do in the case where we
4407             --  don't find any specific indication of an alignment problem.
4408
4409             --  At the outer level, we normally set Unknown as the result in
4410             --  this case, since we can only set Known_Compatible if we really
4411             --  know that the alignment value is OK, but for the recursive
4412             --  call, in the case where the types match, and we have not
4413             --  specified a peculiar alignment for the object, we are only
4414             --  concerned about suspicious rep clauses, the default case does
4415             --  not affect us, since the compiler will, in the absence of such
4416             --  rep clauses, ensure that the alignment is correct.
4417
4418             if Default = Known_Compatible
4419               or else
4420                 (Etype (Obj) = Etype (Expr)
4421                   and then (Unknown_Alignment (Obj)
4422                              or else
4423                                Alignment (Obj) = Alignment (Etype (Obj))))
4424             then
4425                Set_Result
4426                  (Has_Compatible_Alignment_Internal
4427                     (Obj, Prefix (Expr), Known_Compatible));
4428
4429             --  In all other cases, we need a full check on the prefix
4430
4431             else
4432                Set_Result
4433                  (Has_Compatible_Alignment_Internal
4434                     (Obj, Prefix (Expr), Unknown));
4435             end if;
4436          end Check_Prefix;
4437
4438          ----------------
4439          -- Set_Result --
4440          ----------------
4441
4442          procedure Set_Result (R : Alignment_Result) is
4443          begin
4444             if R > Result then
4445                Result := R;
4446             end if;
4447          end Set_Result;
4448
4449       --  Start of processing for Has_Compatible_Alignment_Internal
4450
4451       begin
4452          --  If Expr is a selected component, we must make sure there is no
4453          --  potentially troublesome component clause, and that the record is
4454          --  not packed.
4455
4456          if Nkind (Expr) = N_Selected_Component then
4457
4458             --  Packed record always generate unknown alignment
4459
4460             if Is_Packed (Etype (Prefix (Expr))) then
4461                Set_Result (Unknown);
4462             end if;
4463
4464             --  Check prefix and component offset
4465
4466             Check_Prefix;
4467             Offs := Component_Bit_Offset (Entity (Selector_Name (Expr)));
4468
4469          --  If Expr is an indexed component, we must make sure there is no
4470          --  potentially troublesome Component_Size clause and that the array
4471          --  is not bit-packed.
4472
4473          elsif Nkind (Expr) = N_Indexed_Component then
4474             declare
4475                Typ : constant Entity_Id := Etype (Prefix (Expr));
4476                Ind : constant Node_Id   := First_Index (Typ);
4477
4478             begin
4479                --  Bit packed array always generates unknown alignment
4480
4481                if Is_Bit_Packed_Array (Typ) then
4482                   Set_Result (Unknown);
4483                end if;
4484
4485                --  Check prefix and component offset
4486
4487                Check_Prefix;
4488                Offs := Component_Size (Typ);
4489
4490                --  Small optimization: compute the full offset when possible
4491
4492                if Offs /= No_Uint
4493                  and then Offs > Uint_0
4494                  and then Present (Ind)
4495                  and then Nkind (Ind) = N_Range
4496                  and then Compile_Time_Known_Value (Low_Bound (Ind))
4497                  and then Compile_Time_Known_Value (First (Expressions (Expr)))
4498                then
4499                   Offs := Offs * (Expr_Value (First (Expressions (Expr)))
4500                                     - Expr_Value (Low_Bound ((Ind))));
4501                end if;
4502             end;
4503          end if;
4504
4505          --  If we have a null offset, the result is entirely determined by
4506          --  the base object and has already been computed recursively.
4507
4508          if Offs = Uint_0 then
4509             null;
4510
4511          --  Case where we know the alignment of the object
4512
4513          elsif Known_Alignment (Obj) then
4514             declare
4515                ObjA : constant Uint := Alignment (Obj);
4516                ExpA : Uint          := No_Uint;
4517                SizA : Uint          := No_Uint;
4518
4519             begin
4520                --  If alignment of Obj is 1, then we are always OK
4521
4522                if ObjA = 1 then
4523                   Set_Result (Known_Compatible);
4524
4525                --  Alignment of Obj is greater than 1, so we need to check
4526
4527                else
4528                   --  If we have an offset, see if it is compatible
4529
4530                   if Offs /= No_Uint and Offs > Uint_0 then
4531                      if Offs mod (System_Storage_Unit * ObjA) /= 0 then
4532                         Set_Result (Known_Incompatible);
4533                      end if;
4534
4535                      --  See if Expr is an object with known alignment
4536
4537                   elsif Is_Entity_Name (Expr)
4538                     and then Known_Alignment (Entity (Expr))
4539                   then
4540                      ExpA := Alignment (Entity (Expr));
4541
4542                      --  Otherwise, we can use the alignment of the type of
4543                      --  Expr given that we already checked for
4544                      --  discombobulating rep clauses for the cases of indexed
4545                      --  and selected components above.
4546
4547                   elsif Known_Alignment (Etype (Expr)) then
4548                      ExpA := Alignment (Etype (Expr));
4549
4550                      --  Otherwise the alignment is unknown
4551
4552                   else
4553                      Set_Result (Default);
4554                   end if;
4555
4556                   --  If we got an alignment, see if it is acceptable
4557
4558                   if ExpA /= No_Uint and then ExpA < ObjA then
4559                      Set_Result (Known_Incompatible);
4560                   end if;
4561
4562                   --  If Expr is not a piece of a larger object, see if size
4563                   --  is given. If so, check that it is not too small for the
4564                   --  required alignment.
4565
4566                   if Offs /= No_Uint then
4567                      null;
4568
4569                      --  See if Expr is an object with known size
4570
4571                   elsif Is_Entity_Name (Expr)
4572                     and then Known_Static_Esize (Entity (Expr))
4573                   then
4574                      SizA := Esize (Entity (Expr));
4575
4576                      --  Otherwise, we check the object size of the Expr type
4577
4578                   elsif Known_Static_Esize (Etype (Expr)) then
4579                      SizA := Esize (Etype (Expr));
4580                   end if;
4581
4582                   --  If we got a size, see if it is a multiple of the Obj
4583                   --  alignment, if not, then the alignment cannot be
4584                   --  acceptable, since the size is always a multiple of the
4585                   --  alignment.
4586
4587                   if SizA /= No_Uint then
4588                      if SizA mod (ObjA * Ttypes.System_Storage_Unit) /= 0 then
4589                         Set_Result (Known_Incompatible);
4590                      end if;
4591                   end if;
4592                end if;
4593             end;
4594
4595          --  If we do not know required alignment, any non-zero offset is a
4596          --  potential problem (but certainly may be OK, so result is unknown).
4597
4598          elsif Offs /= No_Uint then
4599             Set_Result (Unknown);
4600
4601          --  If we can't find the result by direct comparison of alignment
4602          --  values, then there is still one case that we can determine known
4603          --  result, and that is when we can determine that the types are the
4604          --  same, and no alignments are specified. Then we known that the
4605          --  alignments are compatible, even if we don't know the alignment
4606          --  value in the front end.
4607
4608          elsif Etype (Obj) = Etype (Expr) then
4609
4610             --  Types are the same, but we have to check for possible size
4611             --  and alignments on the Expr object that may make the alignment
4612             --  different, even though the types are the same.
4613
4614             if Is_Entity_Name (Expr) then
4615
4616                --  First check alignment of the Expr object. Any alignment less
4617                --  than Maximum_Alignment is worrisome since this is the case
4618                --  where we do not know the alignment of Obj.
4619
4620                if Known_Alignment (Entity (Expr))
4621                  and then
4622                    UI_To_Int (Alignment (Entity (Expr))) <
4623                                                     Ttypes.Maximum_Alignment
4624                then
4625                   Set_Result (Unknown);
4626
4627                   --  Now check size of Expr object. Any size that is not an
4628                   --  even multiple of Maximum_Alignment is also worrisome
4629                   --  since it may cause the alignment of the object to be less
4630                   --  than the alignment of the type.
4631
4632                elsif Known_Static_Esize (Entity (Expr))
4633                  and then
4634                    (UI_To_Int (Esize (Entity (Expr))) mod
4635                      (Ttypes.Maximum_Alignment * Ttypes.System_Storage_Unit))
4636                                                                         /= 0
4637                then
4638                   Set_Result (Unknown);
4639
4640                   --  Otherwise same type is decisive
4641
4642                else
4643                   Set_Result (Known_Compatible);
4644                end if;
4645             end if;
4646
4647          --  Another case to deal with is when there is an explicit size or
4648          --  alignment clause when the types are not the same. If so, then the
4649          --  result is Unknown. We don't need to do this test if the Default is
4650          --  Unknown, since that result will be set in any case.
4651
4652          elsif Default /= Unknown
4653            and then (Has_Size_Clause      (Etype (Expr))
4654                       or else
4655                      Has_Alignment_Clause (Etype (Expr)))
4656          then
4657             Set_Result (Unknown);
4658
4659          --  If no indication found, set default
4660
4661          else
4662             Set_Result (Default);
4663          end if;
4664
4665          --  Return worst result found
4666
4667          return Result;
4668       end Has_Compatible_Alignment_Internal;
4669
4670    --  Start of processing for Has_Compatible_Alignment
4671
4672    begin
4673       --  If Obj has no specified alignment, then set alignment from the type
4674       --  alignment. Perhaps we should always do this, but for sure we should
4675       --  do it when there is an address clause since we can do more if the
4676       --  alignment is known.
4677
4678       if Unknown_Alignment (Obj) then
4679          Set_Alignment (Obj, Alignment (Etype (Obj)));
4680       end if;
4681
4682       --  Now do the internal call that does all the work
4683
4684       return Has_Compatible_Alignment_Internal (Obj, Expr, Unknown);
4685    end Has_Compatible_Alignment;
4686
4687    ----------------------
4688    -- Has_Declarations --
4689    ----------------------
4690
4691    function Has_Declarations (N : Node_Id) return Boolean is
4692    begin
4693       return Nkind_In (Nkind (N), N_Accept_Statement,
4694                                   N_Block_Statement,
4695                                   N_Compilation_Unit_Aux,
4696                                   N_Entry_Body,
4697                                   N_Package_Body,
4698                                   N_Protected_Body,
4699                                   N_Subprogram_Body,
4700                                   N_Task_Body,
4701                                   N_Package_Specification);
4702    end Has_Declarations;
4703
4704    -------------------------------------------
4705    -- Has_Discriminant_Dependent_Constraint --
4706    -------------------------------------------
4707
4708    function Has_Discriminant_Dependent_Constraint
4709      (Comp : Entity_Id) return Boolean
4710    is
4711       Comp_Decl  : constant Node_Id := Parent (Comp);
4712       Subt_Indic : constant Node_Id :=
4713                      Subtype_Indication (Component_Definition (Comp_Decl));
4714       Constr     : Node_Id;
4715       Assn       : Node_Id;
4716
4717    begin
4718       if Nkind (Subt_Indic) = N_Subtype_Indication then
4719          Constr := Constraint (Subt_Indic);
4720
4721          if Nkind (Constr) = N_Index_Or_Discriminant_Constraint then
4722             Assn := First (Constraints (Constr));
4723             while Present (Assn) loop
4724                case Nkind (Assn) is
4725                   when N_Subtype_Indication |
4726                        N_Range              |
4727                        N_Identifier
4728                   =>
4729                      if Depends_On_Discriminant (Assn) then
4730                         return True;
4731                      end if;
4732
4733                   when N_Discriminant_Association =>
4734                      if Depends_On_Discriminant (Expression (Assn)) then
4735                         return True;
4736                      end if;
4737
4738                   when others =>
4739                      null;
4740
4741                end case;
4742
4743                Next (Assn);
4744             end loop;
4745          end if;
4746       end if;
4747
4748       return False;
4749    end Has_Discriminant_Dependent_Constraint;
4750
4751    --------------------
4752    -- Has_Infinities --
4753    --------------------
4754
4755    function Has_Infinities (E : Entity_Id) return Boolean is
4756    begin
4757       return
4758         Is_Floating_Point_Type (E)
4759           and then Nkind (Scalar_Range (E)) = N_Range
4760           and then Includes_Infinities (Scalar_Range (E));
4761    end Has_Infinities;
4762
4763    --------------------
4764    -- Has_Interfaces --
4765    --------------------
4766
4767    function Has_Interfaces
4768      (T             : Entity_Id;
4769       Use_Full_View : Boolean := True) return Boolean
4770    is
4771       Typ : Entity_Id := Base_Type (T);
4772
4773    begin
4774       --  Handle concurrent types
4775
4776       if Is_Concurrent_Type (Typ) then
4777          Typ := Corresponding_Record_Type (Typ);
4778       end if;
4779
4780       if not Present (Typ)
4781         or else not Is_Record_Type (Typ)
4782         or else not Is_Tagged_Type (Typ)
4783       then
4784          return False;
4785       end if;
4786
4787       --  Handle private types
4788
4789       if Use_Full_View
4790         and then Present (Full_View (Typ))
4791       then
4792          Typ := Full_View (Typ);
4793       end if;
4794
4795       --  Handle concurrent record types
4796
4797       if Is_Concurrent_Record_Type (Typ)
4798         and then Is_Non_Empty_List (Abstract_Interface_List (Typ))
4799       then
4800          return True;
4801       end if;
4802
4803       loop
4804          if Is_Interface (Typ)
4805            or else
4806              (Is_Record_Type (Typ)
4807                and then Present (Interfaces (Typ))
4808                and then not Is_Empty_Elmt_List (Interfaces (Typ)))
4809          then
4810             return True;
4811          end if;
4812
4813          exit when Etype (Typ) = Typ
4814
4815             --  Handle private types
4816
4817             or else (Present (Full_View (Etype (Typ)))
4818                        and then Full_View (Etype (Typ)) = Typ)
4819
4820             --  Protect the frontend against wrong source with cyclic
4821             --  derivations
4822
4823             or else Etype (Typ) = T;
4824
4825          --  Climb to the ancestor type handling private types
4826
4827          if Present (Full_View (Etype (Typ))) then
4828             Typ := Full_View (Etype (Typ));
4829          else
4830             Typ := Etype (Typ);
4831          end if;
4832       end loop;
4833
4834       return False;
4835    end Has_Interfaces;
4836
4837    ------------------------
4838    -- Has_Null_Exclusion --
4839    ------------------------
4840
4841    function Has_Null_Exclusion (N : Node_Id) return Boolean is
4842    begin
4843       case Nkind (N) is
4844          when N_Access_Definition               |
4845               N_Access_Function_Definition      |
4846               N_Access_Procedure_Definition     |
4847               N_Access_To_Object_Definition     |
4848               N_Allocator                       |
4849               N_Derived_Type_Definition         |
4850               N_Function_Specification          |
4851               N_Subtype_Declaration             =>
4852             return Null_Exclusion_Present (N);
4853
4854          when N_Component_Definition            |
4855               N_Formal_Object_Declaration       |
4856               N_Object_Renaming_Declaration     =>
4857             if Present (Subtype_Mark (N)) then
4858                return Null_Exclusion_Present (N);
4859             else pragma Assert (Present (Access_Definition (N)));
4860                return Null_Exclusion_Present (Access_Definition (N));
4861             end if;
4862
4863          when N_Discriminant_Specification =>
4864             if Nkind (Discriminant_Type (N)) = N_Access_Definition then
4865                return Null_Exclusion_Present (Discriminant_Type (N));
4866             else
4867                return Null_Exclusion_Present (N);
4868             end if;
4869
4870          when N_Object_Declaration =>
4871             if Nkind (Object_Definition (N)) = N_Access_Definition then
4872                return Null_Exclusion_Present (Object_Definition (N));
4873             else
4874                return Null_Exclusion_Present (N);
4875             end if;
4876
4877          when N_Parameter_Specification =>
4878             if Nkind (Parameter_Type (N)) = N_Access_Definition then
4879                return Null_Exclusion_Present (Parameter_Type (N));
4880             else
4881                return Null_Exclusion_Present (N);
4882             end if;
4883
4884          when others =>
4885             return False;
4886
4887       end case;
4888    end Has_Null_Exclusion;
4889
4890    ------------------------
4891    -- Has_Null_Extension --
4892    ------------------------
4893
4894    function Has_Null_Extension (T : Entity_Id) return Boolean is
4895       B     : constant Entity_Id := Base_Type (T);
4896       Comps : Node_Id;
4897       Ext   : Node_Id;
4898
4899    begin
4900       if Nkind (Parent (B)) = N_Full_Type_Declaration
4901         and then Present (Record_Extension_Part (Type_Definition (Parent (B))))
4902       then
4903          Ext := Record_Extension_Part (Type_Definition (Parent (B)));
4904
4905          if Present (Ext) then
4906             if Null_Present (Ext) then
4907                return True;
4908             else
4909                Comps := Component_List (Ext);
4910
4911                --  The null component list is rewritten during analysis to
4912                --  include the parent component. Any other component indicates
4913                --  that the extension was not originally null.
4914
4915                return Null_Present (Comps)
4916                  or else No (Next (First (Component_Items (Comps))));
4917             end if;
4918          else
4919             return False;
4920          end if;
4921
4922       else
4923          return False;
4924       end if;
4925    end Has_Null_Extension;
4926
4927    -------------------------------
4928    -- Has_Overriding_Initialize --
4929    -------------------------------
4930
4931    function Has_Overriding_Initialize (T : Entity_Id) return Boolean is
4932       BT   : constant Entity_Id := Base_Type (T);
4933       P    : Elmt_Id;
4934
4935    begin
4936       if Is_Controlled (BT) then
4937          if Is_RTU (Scope (BT), Ada_Finalization) then
4938             return False;
4939
4940          elsif Present (Primitive_Operations (BT)) then
4941             P := First_Elmt (Primitive_Operations (BT));
4942             while Present (P) loop
4943                declare
4944                   Init : constant Entity_Id := Node (P);
4945                   Formal : constant Entity_Id := First_Formal (Init);
4946                begin
4947                   if Ekind (Init) = E_Procedure
4948                        and then Chars (Init) = Name_Initialize
4949                        and then Comes_From_Source (Init)
4950                        and then Present (Formal)
4951                        and then Etype (Formal) = BT
4952                        and then No (Next_Formal (Formal))
4953                        and then (Ada_Version < Ada_2012
4954                                    or else not Null_Present (Parent (Init)))
4955                   then
4956                      return True;
4957                   end if;
4958                end;
4959
4960                Next_Elmt (P);
4961             end loop;
4962          end if;
4963
4964          --  Here if type itself does not have a non-null Initialize operation:
4965          --  check immediate ancestor.
4966
4967          if Is_Derived_Type (BT)
4968            and then Has_Overriding_Initialize (Etype (BT))
4969          then
4970             return True;
4971          end if;
4972       end if;
4973
4974       return False;
4975    end Has_Overriding_Initialize;
4976
4977    --------------------------------------
4978    -- Has_Preelaborable_Initialization --
4979    --------------------------------------
4980
4981    function Has_Preelaborable_Initialization (E : Entity_Id) return Boolean is
4982       Has_PE : Boolean;
4983
4984       procedure Check_Components (E : Entity_Id);
4985       --  Check component/discriminant chain, sets Has_PE False if a component
4986       --  or discriminant does not meet the preelaborable initialization rules.
4987
4988       ----------------------
4989       -- Check_Components --
4990       ----------------------
4991
4992       procedure Check_Components (E : Entity_Id) is
4993          Ent : Entity_Id;
4994          Exp : Node_Id;
4995
4996          function Is_Preelaborable_Expression (N : Node_Id) return Boolean;
4997          --  Returns True if and only if the expression denoted by N does not
4998          --  violate restrictions on preelaborable constructs (RM-10.2.1(5-9)).
4999
5000          ---------------------------------
5001          -- Is_Preelaborable_Expression --
5002          ---------------------------------
5003
5004          function Is_Preelaborable_Expression (N : Node_Id) return Boolean is
5005             Exp           : Node_Id;
5006             Assn          : Node_Id;
5007             Choice        : Node_Id;
5008             Comp_Type     : Entity_Id;
5009             Is_Array_Aggr : Boolean;
5010
5011          begin
5012             if Is_Static_Expression (N) then
5013                return True;
5014
5015             elsif Nkind (N) = N_Null then
5016                return True;
5017
5018             --  Attributes are allowed in general, even if their prefix is a
5019             --  formal type. (It seems that certain attributes known not to be
5020             --  static might not be allowed, but there are no rules to prevent
5021             --  them.)
5022
5023             elsif Nkind (N) = N_Attribute_Reference then
5024                return True;
5025
5026             --  The name of a discriminant evaluated within its parent type is
5027             --  defined to be preelaborable (10.2.1(8)). Note that we test for
5028             --  names that denote discriminals as well as discriminants to
5029             --  catch references occurring within init procs.
5030
5031             elsif Is_Entity_Name (N)
5032               and then
5033                 (Ekind (Entity (N)) = E_Discriminant
5034                   or else
5035                     ((Ekind (Entity (N)) = E_Constant
5036                        or else Ekind (Entity (N)) = E_In_Parameter)
5037                      and then Present (Discriminal_Link (Entity (N)))))
5038             then
5039                return True;
5040
5041             elsif Nkind (N) = N_Qualified_Expression then
5042                return Is_Preelaborable_Expression (Expression (N));
5043
5044             --  For aggregates we have to check that each of the associations
5045             --  is preelaborable.
5046
5047             elsif Nkind (N) = N_Aggregate
5048               or else Nkind (N) = N_Extension_Aggregate
5049             then
5050                Is_Array_Aggr := Is_Array_Type (Etype (N));
5051
5052                if Is_Array_Aggr then
5053                   Comp_Type := Component_Type (Etype (N));
5054                end if;
5055
5056                --  Check the ancestor part of extension aggregates, which must
5057                --  be either the name of a type that has preelaborable init or
5058                --  an expression that is preelaborable.
5059
5060                if Nkind (N) = N_Extension_Aggregate then
5061                   declare
5062                      Anc_Part : constant Node_Id := Ancestor_Part (N);
5063
5064                   begin
5065                      if Is_Entity_Name (Anc_Part)
5066                        and then Is_Type (Entity (Anc_Part))
5067                      then
5068                         if not Has_Preelaborable_Initialization
5069                                  (Entity (Anc_Part))
5070                         then
5071                            return False;
5072                         end if;
5073
5074                      elsif not Is_Preelaborable_Expression (Anc_Part) then
5075                         return False;
5076                      end if;
5077                   end;
5078                end if;
5079
5080                --  Check positional associations
5081
5082                Exp := First (Expressions (N));
5083                while Present (Exp) loop
5084                   if not Is_Preelaborable_Expression (Exp) then
5085                      return False;
5086                   end if;
5087
5088                   Next (Exp);
5089                end loop;
5090
5091                --  Check named associations
5092
5093                Assn := First (Component_Associations (N));
5094                while Present (Assn) loop
5095                   Choice := First (Choices (Assn));
5096                   while Present (Choice) loop
5097                      if Is_Array_Aggr then
5098                         if Nkind (Choice) = N_Others_Choice then
5099                            null;
5100
5101                         elsif Nkind (Choice) = N_Range then
5102                            if not Is_Static_Range (Choice) then
5103                               return False;
5104                            end if;
5105
5106                         elsif not Is_Static_Expression (Choice) then
5107                            return False;
5108                         end if;
5109
5110                      else
5111                         Comp_Type := Etype (Choice);
5112                      end if;
5113
5114                      Next (Choice);
5115                   end loop;
5116
5117                   --  If the association has a <> at this point, then we have
5118                   --  to check whether the component's type has preelaborable
5119                   --  initialization. Note that this only occurs when the
5120                   --  association's corresponding component does not have a
5121                   --  default expression, the latter case having already been
5122                   --  expanded as an expression for the association.
5123
5124                   if Box_Present (Assn) then
5125                      if not Has_Preelaborable_Initialization (Comp_Type) then
5126                         return False;
5127                      end if;
5128
5129                   --  In the expression case we check whether the expression
5130                   --  is preelaborable.
5131
5132                   elsif
5133                     not Is_Preelaborable_Expression (Expression (Assn))
5134                   then
5135                      return False;
5136                   end if;
5137
5138                   Next (Assn);
5139                end loop;
5140
5141                --  If we get here then aggregate as a whole is preelaborable
5142
5143                return True;
5144
5145             --  All other cases are not preelaborable
5146
5147             else
5148                return False;
5149             end if;
5150          end Is_Preelaborable_Expression;
5151
5152       --  Start of processing for Check_Components
5153
5154       begin
5155          --  Loop through entities of record or protected type
5156
5157          Ent := E;
5158          while Present (Ent) loop
5159
5160             --  We are interested only in components and discriminants
5161
5162             Exp := Empty;
5163
5164             case Ekind (Ent) is
5165                when E_Component =>
5166
5167                   --  Get default expression if any. If there is no declaration
5168                   --  node, it means we have an internal entity. The parent and
5169                   --  tag fields are examples of such entities. For such cases,
5170                   --  we just test the type of the entity.
5171
5172                   if Present (Declaration_Node (Ent)) then
5173                      Exp := Expression (Declaration_Node (Ent));
5174                   end if;
5175
5176                when E_Discriminant =>
5177
5178                   --  Note: for a renamed discriminant, the Declaration_Node
5179                   --  may point to the one from the ancestor, and have a
5180                   --  different expression, so use the proper attribute to
5181                   --  retrieve the expression from the derived constraint.
5182
5183                   Exp := Discriminant_Default_Value (Ent);
5184
5185                when others =>
5186                   goto Check_Next_Entity;
5187             end case;
5188
5189             --  A component has PI if it has no default expression and the
5190             --  component type has PI.
5191
5192             if No (Exp) then
5193                if not Has_Preelaborable_Initialization (Etype (Ent)) then
5194                   Has_PE := False;
5195                   exit;
5196                end if;
5197
5198             --  Require the default expression to be preelaborable
5199
5200             elsif not Is_Preelaborable_Expression (Exp) then
5201                Has_PE := False;
5202                exit;
5203             end if;
5204
5205          <<Check_Next_Entity>>
5206             Next_Entity (Ent);
5207          end loop;
5208       end Check_Components;
5209
5210    --  Start of processing for Has_Preelaborable_Initialization
5211
5212    begin
5213       --  Immediate return if already marked as known preelaborable init. This
5214       --  covers types for which this function has already been called once
5215       --  and returned True (in which case the result is cached), and also
5216       --  types to which a pragma Preelaborable_Initialization applies.
5217
5218       if Known_To_Have_Preelab_Init (E) then
5219          return True;
5220       end if;
5221
5222       --  If the type is a subtype representing a generic actual type, then
5223       --  test whether its base type has preelaborable initialization since
5224       --  the subtype representing the actual does not inherit this attribute
5225       --  from the actual or formal. (but maybe it should???)
5226
5227       if Is_Generic_Actual_Type (E) then
5228          return Has_Preelaborable_Initialization (Base_Type (E));
5229       end if;
5230
5231       --  All elementary types have preelaborable initialization
5232
5233       if Is_Elementary_Type (E) then
5234          Has_PE := True;
5235
5236       --  Array types have PI if the component type has PI
5237
5238       elsif Is_Array_Type (E) then
5239          Has_PE := Has_Preelaborable_Initialization (Component_Type (E));
5240
5241       --  A derived type has preelaborable initialization if its parent type
5242       --  has preelaborable initialization and (in the case of a derived record
5243       --  extension) if the non-inherited components all have preelaborable
5244       --  initialization. However, a user-defined controlled type with an
5245       --  overriding Initialize procedure does not have preelaborable
5246       --  initialization.
5247
5248       elsif Is_Derived_Type (E) then
5249
5250          --  If the derived type is a private extension then it doesn't have
5251          --  preelaborable initialization.
5252
5253          if Ekind (Base_Type (E)) = E_Record_Type_With_Private then
5254             return False;
5255          end if;
5256
5257          --  First check whether ancestor type has preelaborable initialization
5258
5259          Has_PE := Has_Preelaborable_Initialization (Etype (Base_Type (E)));
5260
5261          --  If OK, check extension components (if any)
5262
5263          if Has_PE and then Is_Record_Type (E) then
5264             Check_Components (First_Entity (E));
5265          end if;
5266
5267          --  Check specifically for 10.2.1(11.4/2) exception: a controlled type
5268          --  with a user defined Initialize procedure does not have PI.
5269
5270          if Has_PE
5271            and then Is_Controlled (E)
5272            and then Has_Overriding_Initialize (E)
5273          then
5274             Has_PE := False;
5275          end if;
5276
5277       --  Private types not derived from a type having preelaborable init and
5278       --  that are not marked with pragma Preelaborable_Initialization do not
5279       --  have preelaborable initialization.
5280
5281       elsif Is_Private_Type (E) then
5282          return False;
5283
5284       --  Record type has PI if it is non private and all components have PI
5285
5286       elsif Is_Record_Type (E) then
5287          Has_PE := True;
5288          Check_Components (First_Entity (E));
5289
5290       --  Protected types must not have entries, and components must meet
5291       --  same set of rules as for record components.
5292
5293       elsif Is_Protected_Type (E) then
5294          if Has_Entries (E) then
5295             Has_PE := False;
5296          else
5297             Has_PE := True;
5298             Check_Components (First_Entity (E));
5299             Check_Components (First_Private_Entity (E));
5300          end if;
5301
5302       --  Type System.Address always has preelaborable initialization
5303
5304       elsif Is_RTE (E, RE_Address) then
5305          Has_PE := True;
5306
5307       --  In all other cases, type does not have preelaborable initialization
5308
5309       else
5310          return False;
5311       end if;
5312
5313       --  If type has preelaborable initialization, cache result
5314
5315       if Has_PE then
5316          Set_Known_To_Have_Preelab_Init (E);
5317       end if;
5318
5319       return Has_PE;
5320    end Has_Preelaborable_Initialization;
5321
5322    ---------------------------
5323    -- Has_Private_Component --
5324    ---------------------------
5325
5326    function Has_Private_Component (Type_Id : Entity_Id) return Boolean is
5327       Btype     : Entity_Id := Base_Type (Type_Id);
5328       Component : Entity_Id;
5329
5330    begin
5331       if Error_Posted (Type_Id)
5332         or else Error_Posted (Btype)
5333       then
5334          return False;
5335       end if;
5336
5337       if Is_Class_Wide_Type (Btype) then
5338          Btype := Root_Type (Btype);
5339       end if;
5340
5341       if Is_Private_Type (Btype) then
5342          declare
5343             UT : constant Entity_Id := Underlying_Type (Btype);
5344          begin
5345             if No (UT) then
5346                if No (Full_View (Btype)) then
5347                   return not Is_Generic_Type (Btype)
5348                     and then not Is_Generic_Type (Root_Type (Btype));
5349                else
5350                   return not Is_Generic_Type (Root_Type (Full_View (Btype)));
5351                end if;
5352             else
5353                return not Is_Frozen (UT) and then Has_Private_Component (UT);
5354             end if;
5355          end;
5356
5357       elsif Is_Array_Type (Btype) then
5358          return Has_Private_Component (Component_Type (Btype));
5359
5360       elsif Is_Record_Type (Btype) then
5361          Component := First_Component (Btype);
5362          while Present (Component) loop
5363             if Has_Private_Component (Etype (Component)) then
5364                return True;
5365             end if;
5366
5367             Next_Component (Component);
5368          end loop;
5369
5370          return False;
5371
5372       elsif Is_Protected_Type (Btype)
5373         and then Present (Corresponding_Record_Type (Btype))
5374       then
5375          return Has_Private_Component (Corresponding_Record_Type (Btype));
5376
5377       else
5378          return False;
5379       end if;
5380    end Has_Private_Component;
5381
5382    ----------------
5383    -- Has_Stream --
5384    ----------------
5385
5386    function Has_Stream (T : Entity_Id) return Boolean is
5387       E : Entity_Id;
5388
5389    begin
5390       if No (T) then
5391          return False;
5392
5393       elsif Is_RTE (Root_Type (T), RE_Root_Stream_Type) then
5394          return True;
5395
5396       elsif Is_Array_Type (T) then
5397          return Has_Stream (Component_Type (T));
5398
5399       elsif Is_Record_Type (T) then
5400          E := First_Component (T);
5401          while Present (E) loop
5402             if Has_Stream (Etype (E)) then
5403                return True;
5404             else
5405                Next_Component (E);
5406             end if;
5407          end loop;
5408
5409          return False;
5410
5411       elsif Is_Private_Type (T) then
5412          return Has_Stream (Underlying_Type (T));
5413
5414       else
5415          return False;
5416       end if;
5417    end Has_Stream;
5418
5419    ----------------
5420    -- Has_Suffix --
5421    ----------------
5422
5423    function Has_Suffix (E : Entity_Id; Suffix : Character) return Boolean is
5424    begin
5425       Get_Name_String (Chars (E));
5426       return Name_Buffer (Name_Len) = Suffix;
5427    end Has_Suffix;
5428
5429    --------------------------
5430    -- Has_Tagged_Component --
5431    --------------------------
5432
5433    function Has_Tagged_Component (Typ : Entity_Id) return Boolean is
5434       Comp : Entity_Id;
5435
5436    begin
5437       if Is_Private_Type (Typ)
5438         and then Present (Underlying_Type (Typ))
5439       then
5440          return Has_Tagged_Component (Underlying_Type (Typ));
5441
5442       elsif Is_Array_Type (Typ) then
5443          return Has_Tagged_Component (Component_Type (Typ));
5444
5445       elsif Is_Tagged_Type (Typ) then
5446          return True;
5447
5448       elsif Is_Record_Type (Typ) then
5449          Comp := First_Component (Typ);
5450          while Present (Comp) loop
5451             if Has_Tagged_Component (Etype (Comp)) then
5452                return True;
5453             end if;
5454
5455             Next_Component (Comp);
5456          end loop;
5457
5458          return False;
5459
5460       else
5461          return False;
5462       end if;
5463    end Has_Tagged_Component;
5464
5465    -------------------------
5466    -- Implementation_Kind --
5467    -------------------------
5468
5469    function Implementation_Kind (Subp : Entity_Id) return Name_Id is
5470       Impl_Prag : constant Node_Id := Get_Rep_Pragma (Subp, Name_Implemented);
5471    begin
5472       pragma Assert (Present (Impl_Prag));
5473       return
5474         Chars (Expression (Last (Pragma_Argument_Associations (Impl_Prag))));
5475    end Implementation_Kind;
5476
5477    --------------------------
5478    -- Implements_Interface --
5479    --------------------------
5480
5481    function Implements_Interface
5482      (Typ_Ent         : Entity_Id;
5483       Iface_Ent       : Entity_Id;
5484       Exclude_Parents : Boolean := False) return Boolean
5485    is
5486       Ifaces_List : Elist_Id;
5487       Elmt        : Elmt_Id;
5488       Iface       : Entity_Id := Base_Type (Iface_Ent);
5489       Typ         : Entity_Id := Base_Type (Typ_Ent);
5490
5491    begin
5492       if Is_Class_Wide_Type (Typ) then
5493          Typ := Root_Type (Typ);
5494       end if;
5495
5496       if not Has_Interfaces (Typ) then
5497          return False;
5498       end if;
5499
5500       if Is_Class_Wide_Type (Iface) then
5501          Iface := Root_Type (Iface);
5502       end if;
5503
5504       Collect_Interfaces (Typ, Ifaces_List);
5505
5506       Elmt := First_Elmt (Ifaces_List);
5507       while Present (Elmt) loop
5508          if Is_Ancestor (Node (Elmt), Typ, Use_Full_View => True)
5509            and then Exclude_Parents
5510          then
5511             null;
5512
5513          elsif Node (Elmt) = Iface then
5514             return True;
5515          end if;
5516
5517          Next_Elmt (Elmt);
5518       end loop;
5519
5520       return False;
5521    end Implements_Interface;
5522
5523    -----------------
5524    -- In_Instance --
5525    -----------------
5526
5527    function In_Instance return Boolean is
5528       Curr_Unit : constant Entity_Id := Cunit_Entity (Current_Sem_Unit);
5529       S         : Entity_Id;
5530
5531    begin
5532       S := Current_Scope;
5533       while Present (S)
5534         and then S /= Standard_Standard
5535       loop
5536          if (Ekind (S) = E_Function
5537               or else Ekind (S) = E_Package
5538               or else Ekind (S) = E_Procedure)
5539            and then Is_Generic_Instance (S)
5540          then
5541             --  A child instance is always compiled in the context of a parent
5542             --  instance. Nevertheless, the actuals are not analyzed in an
5543             --  instance context. We detect this case by examining the current
5544             --  compilation unit, which must be a child instance, and checking
5545             --  that it is not currently on the scope stack.
5546
5547             if Is_Child_Unit (Curr_Unit)
5548               and then
5549                 Nkind (Unit (Cunit (Current_Sem_Unit)))
5550                   = N_Package_Instantiation
5551               and then not In_Open_Scopes (Curr_Unit)
5552             then
5553                return False;
5554             else
5555                return True;
5556             end if;
5557          end if;
5558
5559          S := Scope (S);
5560       end loop;
5561
5562       return False;
5563    end In_Instance;
5564
5565    ----------------------
5566    -- In_Instance_Body --
5567    ----------------------
5568
5569    function In_Instance_Body return Boolean is
5570       S : Entity_Id;
5571
5572    begin
5573       S := Current_Scope;
5574       while Present (S)
5575         and then S /= Standard_Standard
5576       loop
5577          if (Ekind (S) = E_Function
5578               or else Ekind (S) = E_Procedure)
5579            and then Is_Generic_Instance (S)
5580          then
5581             return True;
5582
5583          elsif Ekind (S) = E_Package
5584            and then In_Package_Body (S)
5585            and then Is_Generic_Instance (S)
5586          then
5587             return True;
5588          end if;
5589
5590          S := Scope (S);
5591       end loop;
5592
5593       return False;
5594    end In_Instance_Body;
5595
5596    -----------------------------
5597    -- In_Instance_Not_Visible --
5598    -----------------------------
5599
5600    function In_Instance_Not_Visible return Boolean is
5601       S : Entity_Id;
5602
5603    begin
5604       S := Current_Scope;
5605       while Present (S)
5606         and then S /= Standard_Standard
5607       loop
5608          if (Ekind (S) = E_Function
5609               or else Ekind (S) = E_Procedure)
5610            and then Is_Generic_Instance (S)
5611          then
5612             return True;
5613
5614          elsif Ekind (S) = E_Package
5615            and then (In_Package_Body (S) or else In_Private_Part (S))
5616            and then Is_Generic_Instance (S)
5617          then
5618             return True;
5619          end if;
5620
5621          S := Scope (S);
5622       end loop;
5623
5624       return False;
5625    end In_Instance_Not_Visible;
5626
5627    ------------------------------
5628    -- In_Instance_Visible_Part --
5629    ------------------------------
5630
5631    function In_Instance_Visible_Part return Boolean is
5632       S : Entity_Id;
5633
5634    begin
5635       S := Current_Scope;
5636       while Present (S)
5637         and then S /= Standard_Standard
5638       loop
5639          if Ekind (S) = E_Package
5640            and then Is_Generic_Instance (S)
5641            and then not In_Package_Body (S)
5642            and then not In_Private_Part (S)
5643          then
5644             return True;
5645          end if;
5646
5647          S := Scope (S);
5648       end loop;
5649
5650       return False;
5651    end In_Instance_Visible_Part;
5652
5653    ---------------------
5654    -- In_Package_Body --
5655    ---------------------
5656
5657    function In_Package_Body return Boolean is
5658       S : Entity_Id;
5659
5660    begin
5661       S := Current_Scope;
5662       while Present (S)
5663         and then S /= Standard_Standard
5664       loop
5665          if Ekind (S) = E_Package
5666            and then In_Package_Body (S)
5667          then
5668             return True;
5669          else
5670             S := Scope (S);
5671          end if;
5672       end loop;
5673
5674       return False;
5675    end In_Package_Body;
5676
5677    --------------------------------
5678    -- In_Parameter_Specification --
5679    --------------------------------
5680
5681    function In_Parameter_Specification (N : Node_Id) return Boolean is
5682       PN : Node_Id;
5683
5684    begin
5685       PN := Parent (N);
5686       while Present (PN) loop
5687          if Nkind (PN) = N_Parameter_Specification then
5688             return True;
5689          end if;
5690
5691          PN := Parent (PN);
5692       end loop;
5693
5694       return False;
5695    end In_Parameter_Specification;
5696
5697    --------------------------------------
5698    -- In_Subprogram_Or_Concurrent_Unit --
5699    --------------------------------------
5700
5701    function In_Subprogram_Or_Concurrent_Unit return Boolean is
5702       E : Entity_Id;
5703       K : Entity_Kind;
5704
5705    begin
5706       --  Use scope chain to check successively outer scopes
5707
5708       E := Current_Scope;
5709       loop
5710          K := Ekind (E);
5711
5712          if K in Subprogram_Kind
5713            or else K in Concurrent_Kind
5714            or else K in Generic_Subprogram_Kind
5715          then
5716             return True;
5717
5718          elsif E = Standard_Standard then
5719             return False;
5720          end if;
5721
5722          E := Scope (E);
5723       end loop;
5724    end In_Subprogram_Or_Concurrent_Unit;
5725
5726    ---------------------
5727    -- In_Visible_Part --
5728    ---------------------
5729
5730    function In_Visible_Part (Scope_Id : Entity_Id) return Boolean is
5731    begin
5732       return
5733         Is_Package_Or_Generic_Package (Scope_Id)
5734           and then In_Open_Scopes (Scope_Id)
5735           and then not In_Package_Body (Scope_Id)
5736           and then not In_Private_Part (Scope_Id);
5737    end In_Visible_Part;
5738
5739    ---------------------------------
5740    -- Insert_Explicit_Dereference --
5741    ---------------------------------
5742
5743    procedure Insert_Explicit_Dereference (N : Node_Id) is
5744       New_Prefix : constant Node_Id := Relocate_Node (N);
5745       Ent        : Entity_Id := Empty;
5746       Pref       : Node_Id;
5747       I          : Interp_Index;
5748       It         : Interp;
5749       T          : Entity_Id;
5750
5751    begin
5752       Save_Interps (N, New_Prefix);
5753
5754       Rewrite (N,
5755         Make_Explicit_Dereference (Sloc (Parent (N)),
5756           Prefix => New_Prefix));
5757
5758       Set_Etype (N, Designated_Type (Etype (New_Prefix)));
5759
5760       if Is_Overloaded (New_Prefix) then
5761
5762          --  The dereference is also overloaded, and its interpretations are
5763          --  the designated types of the interpretations of the original node.
5764
5765          Set_Etype (N, Any_Type);
5766
5767          Get_First_Interp (New_Prefix, I, It);
5768          while Present (It.Nam) loop
5769             T := It.Typ;
5770
5771             if Is_Access_Type (T) then
5772                Add_One_Interp (N, Designated_Type (T), Designated_Type (T));
5773             end if;
5774
5775             Get_Next_Interp (I, It);
5776          end loop;
5777
5778          End_Interp_List;
5779
5780       else
5781          --  Prefix is unambiguous: mark the original prefix (which might
5782          --  Come_From_Source) as a reference, since the new (relocated) one
5783          --  won't be taken into account.
5784
5785          if Is_Entity_Name (New_Prefix) then
5786             Ent := Entity (New_Prefix);
5787             Pref := New_Prefix;
5788
5789          --  For a retrieval of a subcomponent of some composite object,
5790          --  retrieve the ultimate entity if there is one.
5791
5792          elsif Nkind (New_Prefix) = N_Selected_Component
5793            or else Nkind (New_Prefix) = N_Indexed_Component
5794          then
5795             Pref := Prefix (New_Prefix);
5796             while Present (Pref)
5797               and then
5798                 (Nkind (Pref) = N_Selected_Component
5799                   or else Nkind (Pref) = N_Indexed_Component)
5800             loop
5801                Pref := Prefix (Pref);
5802             end loop;
5803
5804             if Present (Pref) and then Is_Entity_Name (Pref) then
5805                Ent := Entity (Pref);
5806             end if;
5807          end if;
5808
5809          --  Place the reference on the entity node
5810
5811          if Present (Ent) then
5812             Generate_Reference (Ent, Pref);
5813          end if;
5814       end if;
5815    end Insert_Explicit_Dereference;
5816
5817    ------------------------------------------
5818    -- Inspect_Deferred_Constant_Completion --
5819    ------------------------------------------
5820
5821    procedure Inspect_Deferred_Constant_Completion (Decls : List_Id) is
5822       Decl   : Node_Id;
5823
5824    begin
5825       Decl := First (Decls);
5826       while Present (Decl) loop
5827
5828          --  Deferred constant signature
5829
5830          if Nkind (Decl) = N_Object_Declaration
5831            and then Constant_Present (Decl)
5832            and then No (Expression (Decl))
5833
5834             --  No need to check internally generated constants
5835
5836            and then Comes_From_Source (Decl)
5837
5838             --  The constant is not completed. A full object declaration or a
5839             --  pragma Import complete a deferred constant.
5840
5841            and then not Has_Completion (Defining_Identifier (Decl))
5842          then
5843             Error_Msg_N
5844               ("constant declaration requires initialization expression",
5845               Defining_Identifier (Decl));
5846          end if;
5847
5848          Decl := Next (Decl);
5849       end loop;
5850    end Inspect_Deferred_Constant_Completion;
5851
5852    -----------------------------
5853    -- Is_Actual_Out_Parameter --
5854    -----------------------------
5855
5856    function Is_Actual_Out_Parameter (N : Node_Id) return Boolean is
5857       Formal : Entity_Id;
5858       Call   : Node_Id;
5859    begin
5860       Find_Actual (N, Formal, Call);
5861       return Present (Formal) and then Ekind (Formal) = E_Out_Parameter;
5862    end Is_Actual_Out_Parameter;
5863
5864    -------------------------
5865    -- Is_Actual_Parameter --
5866    -------------------------
5867
5868    function Is_Actual_Parameter (N : Node_Id) return Boolean is
5869       PK : constant Node_Kind := Nkind (Parent (N));
5870
5871    begin
5872       case PK is
5873          when N_Parameter_Association =>
5874             return N = Explicit_Actual_Parameter (Parent (N));
5875
5876          when N_Function_Call | N_Procedure_Call_Statement =>
5877             return Is_List_Member (N)
5878               and then
5879                 List_Containing (N) = Parameter_Associations (Parent (N));
5880
5881          when others =>
5882             return False;
5883       end case;
5884    end Is_Actual_Parameter;
5885
5886    ---------------------
5887    -- Is_Aliased_View --
5888    ---------------------
5889
5890    function Is_Aliased_View (Obj : Node_Id) return Boolean is
5891       E : Entity_Id;
5892
5893    begin
5894       if Is_Entity_Name (Obj) then
5895
5896          E := Entity (Obj);
5897
5898          return
5899            (Is_Object (E)
5900              and then
5901                (Is_Aliased (E)
5902                   or else (Present (Renamed_Object (E))
5903                              and then Is_Aliased_View (Renamed_Object (E)))))
5904
5905            or else ((Is_Formal (E)
5906                       or else Ekind (E) = E_Generic_In_Out_Parameter
5907                       or else Ekind (E) = E_Generic_In_Parameter)
5908                     and then Is_Tagged_Type (Etype (E)))
5909
5910            or else (Is_Concurrent_Type (E)
5911                      and then In_Open_Scopes (E))
5912
5913             --  Current instance of type, either directly or as rewritten
5914             --  reference to the current object.
5915
5916            or else (Is_Entity_Name (Original_Node (Obj))
5917                      and then Present (Entity (Original_Node (Obj)))
5918                      and then Is_Type (Entity (Original_Node (Obj))))
5919
5920            or else (Is_Type (E) and then E = Current_Scope)
5921
5922            or else (Is_Incomplete_Or_Private_Type (E)
5923                      and then Full_View (E) = Current_Scope);
5924
5925       elsif Nkind (Obj) = N_Selected_Component then
5926          return Is_Aliased (Entity (Selector_Name (Obj)));
5927
5928       elsif Nkind (Obj) = N_Indexed_Component then
5929          return Has_Aliased_Components (Etype (Prefix (Obj)))
5930            or else
5931              (Is_Access_Type (Etype (Prefix (Obj)))
5932                and then
5933               Has_Aliased_Components
5934                 (Designated_Type (Etype (Prefix (Obj)))));
5935
5936       elsif Nkind (Obj) = N_Unchecked_Type_Conversion
5937         or else Nkind (Obj) = N_Type_Conversion
5938       then
5939          return Is_Tagged_Type (Etype (Obj))
5940            and then Is_Aliased_View (Expression (Obj));
5941
5942       elsif Nkind (Obj) = N_Explicit_Dereference then
5943          return Nkind (Original_Node (Obj)) /= N_Function_Call;
5944
5945       else
5946          return False;
5947       end if;
5948    end Is_Aliased_View;
5949
5950    -------------------------
5951    -- Is_Ancestor_Package --
5952    -------------------------
5953
5954    function Is_Ancestor_Package
5955      (E1 : Entity_Id;
5956       E2 : Entity_Id) return Boolean
5957    is
5958       Par : Entity_Id;
5959
5960    begin
5961       Par := E2;
5962       while Present (Par)
5963         and then Par /= Standard_Standard
5964       loop
5965          if Par = E1 then
5966             return True;
5967          end if;
5968
5969          Par := Scope (Par);
5970       end loop;
5971
5972       return False;
5973    end Is_Ancestor_Package;
5974
5975    ----------------------
5976    -- Is_Atomic_Object --
5977    ----------------------
5978
5979    function Is_Atomic_Object (N : Node_Id) return Boolean is
5980
5981       function Object_Has_Atomic_Components (N : Node_Id) return Boolean;
5982       --  Determines if given object has atomic components
5983
5984       function Is_Atomic_Prefix (N : Node_Id) return Boolean;
5985       --  If prefix is an implicit dereference, examine designated type
5986
5987       ----------------------
5988       -- Is_Atomic_Prefix --
5989       ----------------------
5990
5991       function Is_Atomic_Prefix (N : Node_Id) return Boolean is
5992       begin
5993          if Is_Access_Type (Etype (N)) then
5994             return
5995               Has_Atomic_Components (Designated_Type (Etype (N)));
5996          else
5997             return Object_Has_Atomic_Components (N);
5998          end if;
5999       end Is_Atomic_Prefix;
6000
6001       ----------------------------------
6002       -- Object_Has_Atomic_Components --
6003       ----------------------------------
6004
6005       function Object_Has_Atomic_Components (N : Node_Id) return Boolean is
6006       begin
6007          if Has_Atomic_Components (Etype (N))
6008            or else Is_Atomic (Etype (N))
6009          then
6010             return True;
6011
6012          elsif Is_Entity_Name (N)
6013            and then (Has_Atomic_Components (Entity (N))
6014                       or else Is_Atomic (Entity (N)))
6015          then
6016             return True;
6017
6018          elsif Nkind (N) = N_Indexed_Component
6019            or else Nkind (N) = N_Selected_Component
6020          then
6021             return Is_Atomic_Prefix (Prefix (N));
6022
6023          else
6024             return False;
6025          end if;
6026       end Object_Has_Atomic_Components;
6027
6028    --  Start of processing for Is_Atomic_Object
6029
6030    begin
6031       --  Predicate is not relevant to subprograms
6032
6033       if Is_Entity_Name (N) and then Is_Overloadable (Entity (N)) then
6034          return False;
6035
6036       elsif Is_Atomic (Etype (N))
6037         or else (Is_Entity_Name (N) and then Is_Atomic (Entity (N)))
6038       then
6039          return True;
6040
6041       elsif Nkind (N) = N_Indexed_Component
6042         or else Nkind (N) = N_Selected_Component
6043       then
6044          return Is_Atomic_Prefix (Prefix (N));
6045
6046       else
6047          return False;
6048       end if;
6049    end Is_Atomic_Object;
6050
6051    -------------------------
6052    -- Is_Coextension_Root --
6053    -------------------------
6054
6055    function Is_Coextension_Root (N : Node_Id) return Boolean is
6056    begin
6057       return
6058         Nkind (N) = N_Allocator
6059           and then Present (Coextensions (N))
6060
6061          --  Anonymous access discriminants carry a list of all nested
6062          --  controlled coextensions.
6063
6064           and then not Is_Dynamic_Coextension (N)
6065           and then not Is_Static_Coextension (N);
6066    end Is_Coextension_Root;
6067
6068    -----------------------------
6069    -- Is_Concurrent_Interface --
6070    -----------------------------
6071
6072    function Is_Concurrent_Interface (T : Entity_Id) return Boolean is
6073    begin
6074       return
6075         Is_Interface (T)
6076           and then
6077             (Is_Protected_Interface (T)
6078                or else Is_Synchronized_Interface (T)
6079                or else Is_Task_Interface (T));
6080    end Is_Concurrent_Interface;
6081
6082    --------------------------------------
6083    -- Is_Controlling_Limited_Procedure --
6084    --------------------------------------
6085
6086    function Is_Controlling_Limited_Procedure
6087      (Proc_Nam : Entity_Id) return Boolean
6088    is
6089       Param_Typ : Entity_Id := Empty;
6090
6091    begin
6092       if Ekind (Proc_Nam) = E_Procedure
6093         and then Present (Parameter_Specifications (Parent (Proc_Nam)))
6094       then
6095          Param_Typ := Etype (Parameter_Type (First (
6096                         Parameter_Specifications (Parent (Proc_Nam)))));
6097
6098       --  In this case where an Itype was created, the procedure call has been
6099       --  rewritten.
6100
6101       elsif Present (Associated_Node_For_Itype (Proc_Nam))
6102         and then Present (Original_Node (Associated_Node_For_Itype (Proc_Nam)))
6103         and then
6104           Present (Parameter_Associations
6105                      (Associated_Node_For_Itype (Proc_Nam)))
6106       then
6107          Param_Typ :=
6108            Etype (First (Parameter_Associations
6109                           (Associated_Node_For_Itype (Proc_Nam))));
6110       end if;
6111
6112       if Present (Param_Typ) then
6113          return
6114            Is_Interface (Param_Typ)
6115              and then Is_Limited_Record (Param_Typ);
6116       end if;
6117
6118       return False;
6119    end Is_Controlling_Limited_Procedure;
6120
6121    -----------------------------
6122    -- Is_CPP_Constructor_Call --
6123    -----------------------------
6124
6125    function Is_CPP_Constructor_Call (N : Node_Id) return Boolean is
6126    begin
6127       return Nkind (N) = N_Function_Call
6128         and then Is_CPP_Class (Etype (Etype (N)))
6129         and then Is_Constructor (Entity (Name (N)))
6130         and then Is_Imported (Entity (Name (N)));
6131    end Is_CPP_Constructor_Call;
6132
6133    -----------------
6134    -- Is_Delegate --
6135    -----------------
6136
6137    function Is_Delegate (T : Entity_Id) return Boolean is
6138       Desig_Type : Entity_Id;
6139
6140    begin
6141       if VM_Target /= CLI_Target then
6142          return False;
6143       end if;
6144
6145       --  Access-to-subprograms are delegates in CIL
6146
6147       if Ekind (T) = E_Access_Subprogram_Type then
6148          return True;
6149       end if;
6150
6151       if Ekind (T) not in Access_Kind then
6152
6153          --  A delegate is a managed pointer. If no designated type is defined
6154          --  it means that it's not a delegate.
6155
6156          return False;
6157       end if;
6158
6159       Desig_Type := Etype (Directly_Designated_Type (T));
6160
6161       if not Is_Tagged_Type (Desig_Type) then
6162          return False;
6163       end if;
6164
6165       --  Test if the type is inherited from [mscorlib]System.Delegate
6166
6167       while Etype (Desig_Type) /= Desig_Type loop
6168          if Chars (Scope (Desig_Type)) /= No_Name
6169            and then Is_Imported (Scope (Desig_Type))
6170            and then Get_Name_String (Chars (Scope (Desig_Type))) = "delegate"
6171          then
6172             return True;
6173          end if;
6174
6175          Desig_Type := Etype (Desig_Type);
6176       end loop;
6177
6178       return False;
6179    end Is_Delegate;
6180
6181    ----------------------------------------------
6182    -- Is_Dependent_Component_Of_Mutable_Object --
6183    ----------------------------------------------
6184
6185    function Is_Dependent_Component_Of_Mutable_Object
6186      (Object : Node_Id) return Boolean
6187    is
6188       P           : Node_Id;
6189       Prefix_Type : Entity_Id;
6190       P_Aliased   : Boolean := False;
6191       Comp        : Entity_Id;
6192
6193       function Is_Declared_Within_Variant (Comp : Entity_Id) return Boolean;
6194       --  Returns True if and only if Comp is declared within a variant part
6195
6196       --------------------------------
6197       -- Is_Declared_Within_Variant --
6198       --------------------------------
6199
6200       function Is_Declared_Within_Variant (Comp : Entity_Id) return Boolean is
6201          Comp_Decl : constant Node_Id   := Parent (Comp);
6202          Comp_List : constant Node_Id   := Parent (Comp_Decl);
6203       begin
6204          return Nkind (Parent (Comp_List)) = N_Variant;
6205       end Is_Declared_Within_Variant;
6206
6207    --  Start of processing for Is_Dependent_Component_Of_Mutable_Object
6208
6209    begin
6210       if Is_Variable (Object) then
6211
6212          if Nkind (Object) = N_Selected_Component then
6213             P := Prefix (Object);
6214             Prefix_Type := Etype (P);
6215
6216             if Is_Entity_Name (P) then
6217
6218                if Ekind (Entity (P)) = E_Generic_In_Out_Parameter then
6219                   Prefix_Type := Base_Type (Prefix_Type);
6220                end if;
6221
6222                if Is_Aliased (Entity (P)) then
6223                   P_Aliased := True;
6224                end if;
6225
6226             --  A discriminant check on a selected component may be expanded
6227             --  into a dereference when removing side-effects. Recover the
6228             --  original node and its type, which may be unconstrained.
6229
6230             elsif Nkind (P) = N_Explicit_Dereference
6231               and then not (Comes_From_Source (P))
6232             then
6233                P := Original_Node (P);
6234                Prefix_Type := Etype (P);
6235
6236             else
6237                --  Check for prefix being an aliased component???
6238
6239                null;
6240
6241             end if;
6242
6243             --  A heap object is constrained by its initial value
6244
6245             --  Ada 2005 (AI-363): Always assume the object could be mutable in
6246             --  the dereferenced case, since the access value might denote an
6247             --  unconstrained aliased object, whereas in Ada 95 the designated
6248             --  object is guaranteed to be constrained. A worst-case assumption
6249             --  has to apply in Ada 2005 because we can't tell at compile time
6250             --  whether the object is "constrained by its initial value"
6251             --  (despite the fact that 3.10.2(26/2) and 8.5.1(5/2) are
6252             --  semantic rules -- these rules are acknowledged to need fixing).
6253
6254             if Ada_Version < Ada_2005 then
6255                if Is_Access_Type (Prefix_Type)
6256                  or else Nkind (P) = N_Explicit_Dereference
6257                then
6258                   return False;
6259                end if;
6260
6261             elsif Ada_Version >= Ada_2005 then
6262                if Is_Access_Type (Prefix_Type) then
6263
6264                   --  If the access type is pool-specific, and there is no
6265                   --  constrained partial view of the designated type, then the
6266                   --  designated object is known to be constrained.
6267
6268                   if Ekind (Prefix_Type) = E_Access_Type
6269                     and then not Has_Constrained_Partial_View
6270                                    (Designated_Type (Prefix_Type))
6271                   then
6272                      return False;
6273
6274                   --  Otherwise (general access type, or there is a constrained
6275                   --  partial view of the designated type), we need to check
6276                   --  based on the designated type.
6277
6278                   else
6279                      Prefix_Type := Designated_Type (Prefix_Type);
6280                   end if;
6281                end if;
6282             end if;
6283
6284             Comp :=
6285               Original_Record_Component (Entity (Selector_Name (Object)));
6286
6287             --  As per AI-0017, the renaming is illegal in a generic body, even
6288             --  if the subtype is indefinite.
6289
6290             --  Ada 2005 (AI-363): In Ada 2005 an aliased object can be mutable
6291
6292             if not Is_Constrained (Prefix_Type)
6293               and then (not Is_Indefinite_Subtype (Prefix_Type)
6294                          or else
6295                           (Is_Generic_Type (Prefix_Type)
6296                             and then Ekind (Current_Scope) = E_Generic_Package
6297                             and then In_Package_Body (Current_Scope)))
6298
6299               and then (Is_Declared_Within_Variant (Comp)
6300                           or else Has_Discriminant_Dependent_Constraint (Comp))
6301               and then (not P_Aliased or else Ada_Version >= Ada_2005)
6302             then
6303                return True;
6304
6305             else
6306                return
6307                  Is_Dependent_Component_Of_Mutable_Object (Prefix (Object));
6308
6309             end if;
6310
6311          elsif Nkind (Object) = N_Indexed_Component
6312            or else Nkind (Object) = N_Slice
6313          then
6314             return Is_Dependent_Component_Of_Mutable_Object (Prefix (Object));
6315
6316          --  A type conversion that Is_Variable is a view conversion:
6317          --  go back to the denoted object.
6318
6319          elsif Nkind (Object) = N_Type_Conversion then
6320             return
6321               Is_Dependent_Component_Of_Mutable_Object (Expression (Object));
6322          end if;
6323       end if;
6324
6325       return False;
6326    end Is_Dependent_Component_Of_Mutable_Object;
6327
6328    ---------------------
6329    -- Is_Dereferenced --
6330    ---------------------
6331
6332    function Is_Dereferenced (N : Node_Id) return Boolean is
6333       P : constant Node_Id := Parent (N);
6334    begin
6335       return
6336          (Nkind (P) = N_Selected_Component
6337             or else
6338           Nkind (P) = N_Explicit_Dereference
6339             or else
6340           Nkind (P) = N_Indexed_Component
6341             or else
6342           Nkind (P) = N_Slice)
6343         and then Prefix (P) = N;
6344    end Is_Dereferenced;
6345
6346    ----------------------
6347    -- Is_Descendent_Of --
6348    ----------------------
6349
6350    function Is_Descendent_Of (T1 : Entity_Id; T2 : Entity_Id) return Boolean is
6351       T    : Entity_Id;
6352       Etyp : Entity_Id;
6353
6354    begin
6355       pragma Assert (Nkind (T1) in N_Entity);
6356       pragma Assert (Nkind (T2) in N_Entity);
6357
6358       T := Base_Type (T1);
6359
6360       --  Immediate return if the types match
6361
6362       if T = T2 then
6363          return True;
6364
6365       --  Comment needed here ???
6366
6367       elsif Ekind (T) = E_Class_Wide_Type then
6368          return Etype (T) = T2;
6369
6370       --  All other cases
6371
6372       else
6373          loop
6374             Etyp := Etype (T);
6375
6376             --  Done if we found the type we are looking for
6377
6378             if Etyp = T2 then
6379                return True;
6380
6381             --  Done if no more derivations to check
6382
6383             elsif T = T1
6384               or else T = Etyp
6385             then
6386                return False;
6387
6388             --  Following test catches error cases resulting from prev errors
6389
6390             elsif No (Etyp) then
6391                return False;
6392
6393             elsif Is_Private_Type (T) and then Etyp = Full_View (T) then
6394                return False;
6395
6396             elsif Is_Private_Type (Etyp) and then Full_View (Etyp) = T then
6397                return False;
6398             end if;
6399
6400             T := Base_Type (Etyp);
6401          end loop;
6402       end if;
6403    end Is_Descendent_Of;
6404
6405    --------------
6406    -- Is_False --
6407    --------------
6408
6409    function Is_False (U : Uint) return Boolean is
6410    begin
6411       return (U = 0);
6412    end Is_False;
6413
6414    ---------------------------
6415    -- Is_Fixed_Model_Number --
6416    ---------------------------
6417
6418    function Is_Fixed_Model_Number (U : Ureal; T : Entity_Id) return Boolean is
6419       S : constant Ureal := Small_Value (T);
6420       M : Urealp.Save_Mark;
6421       R : Boolean;
6422    begin
6423       M := Urealp.Mark;
6424       R := (U = UR_Trunc (U / S) * S);
6425       Urealp.Release (M);
6426       return R;
6427    end Is_Fixed_Model_Number;
6428
6429    -------------------------------
6430    -- Is_Fully_Initialized_Type --
6431    -------------------------------
6432
6433    function Is_Fully_Initialized_Type (Typ : Entity_Id) return Boolean is
6434    begin
6435       if Is_Scalar_Type (Typ) then
6436          return False;
6437
6438       elsif Is_Access_Type (Typ) then
6439          return True;
6440
6441       elsif Is_Array_Type (Typ) then
6442          if Is_Fully_Initialized_Type (Component_Type (Typ)) then
6443             return True;
6444          end if;
6445
6446          --  An interesting case, if we have a constrained type one of whose
6447          --  bounds is known to be null, then there are no elements to be
6448          --  initialized, so all the elements are initialized!
6449
6450          if Is_Constrained (Typ) then
6451             declare
6452                Indx     : Node_Id;
6453                Indx_Typ : Entity_Id;
6454                Lbd, Hbd : Node_Id;
6455
6456             begin
6457                Indx := First_Index (Typ);
6458                while Present (Indx) loop
6459                   if Etype (Indx) = Any_Type then
6460                      return False;
6461
6462                   --  If index is a range, use directly
6463
6464                   elsif Nkind (Indx) = N_Range then
6465                      Lbd := Low_Bound  (Indx);
6466                      Hbd := High_Bound (Indx);
6467
6468                   else
6469                      Indx_Typ := Etype (Indx);
6470
6471                      if Is_Private_Type (Indx_Typ)  then
6472                         Indx_Typ := Full_View (Indx_Typ);
6473                      end if;
6474
6475                      if No (Indx_Typ) or else Etype (Indx_Typ) = Any_Type then
6476                         return False;
6477                      else
6478                         Lbd := Type_Low_Bound  (Indx_Typ);
6479                         Hbd := Type_High_Bound (Indx_Typ);
6480                      end if;
6481                   end if;
6482
6483                   if Compile_Time_Known_Value (Lbd)
6484                     and then Compile_Time_Known_Value (Hbd)
6485                   then
6486                      if Expr_Value (Hbd) < Expr_Value (Lbd) then
6487                         return True;
6488                      end if;
6489                   end if;
6490
6491                   Next_Index (Indx);
6492                end loop;
6493             end;
6494          end if;
6495
6496          --  If no null indexes, then type is not fully initialized
6497
6498          return False;
6499
6500       --  Record types
6501
6502       elsif Is_Record_Type (Typ) then
6503          if Has_Discriminants (Typ)
6504            and then
6505              Present (Discriminant_Default_Value (First_Discriminant (Typ)))
6506            and then Is_Fully_Initialized_Variant (Typ)
6507          then
6508             return True;
6509          end if;
6510
6511          --  Controlled records are considered to be fully initialized if
6512          --  there is a user defined Initialize routine. This may not be
6513          --  entirely correct, but as the spec notes, we are guessing here
6514          --  what is best from the point of view of issuing warnings.
6515
6516          if Is_Controlled (Typ) then
6517             declare
6518                Utyp : constant Entity_Id := Underlying_Type (Typ);
6519
6520             begin
6521                if Present (Utyp) then
6522                   declare
6523                      Init : constant Entity_Id :=
6524                               (Find_Prim_Op
6525                                  (Underlying_Type (Typ), Name_Initialize));
6526
6527                   begin
6528                      if Present (Init)
6529                        and then Comes_From_Source (Init)
6530                        and then not
6531                          Is_Predefined_File_Name
6532                            (File_Name (Get_Source_File_Index (Sloc (Init))))
6533                      then
6534                         return True;
6535
6536                      elsif Has_Null_Extension (Typ)
6537                         and then
6538                           Is_Fully_Initialized_Type
6539                             (Etype (Base_Type (Typ)))
6540                      then
6541                         return True;
6542                      end if;
6543                   end;
6544                end if;
6545             end;
6546          end if;
6547
6548          --  Otherwise see if all record components are initialized
6549
6550          declare
6551             Ent : Entity_Id;
6552
6553          begin
6554             Ent := First_Entity (Typ);
6555             while Present (Ent) loop
6556                if Chars (Ent) = Name_uController then
6557                   null;
6558
6559                elsif Ekind (Ent) = E_Component
6560                  and then (No (Parent (Ent))
6561                              or else No (Expression (Parent (Ent))))
6562                  and then not Is_Fully_Initialized_Type (Etype (Ent))
6563
6564                   --  Special VM case for tag components, which need to be
6565                   --  defined in this case, but are never initialized as VMs
6566                   --  are using other dispatching mechanisms. Ignore this
6567                   --  uninitialized case. Note that this applies both to the
6568                   --  uTag entry and the main vtable pointer (CPP_Class case).
6569
6570                  and then (Tagged_Type_Expansion or else not Is_Tag (Ent))
6571                then
6572                   return False;
6573                end if;
6574
6575                Next_Entity (Ent);
6576             end loop;
6577          end;
6578
6579          --  No uninitialized components, so type is fully initialized.
6580          --  Note that this catches the case of no components as well.
6581
6582          return True;
6583
6584       elsif Is_Concurrent_Type (Typ) then
6585          return True;
6586
6587       elsif Is_Private_Type (Typ) then
6588          declare
6589             U : constant Entity_Id := Underlying_Type (Typ);
6590
6591          begin
6592             if No (U) then
6593                return False;
6594             else
6595                return Is_Fully_Initialized_Type (U);
6596             end if;
6597          end;
6598
6599       else
6600          return False;
6601       end if;
6602    end Is_Fully_Initialized_Type;
6603
6604    ----------------------------------
6605    -- Is_Fully_Initialized_Variant --
6606    ----------------------------------
6607
6608    function Is_Fully_Initialized_Variant (Typ : Entity_Id) return Boolean is
6609       Loc           : constant Source_Ptr := Sloc (Typ);
6610       Constraints   : constant List_Id    := New_List;
6611       Components    : constant Elist_Id   := New_Elmt_List;
6612       Comp_Elmt     : Elmt_Id;
6613       Comp_Id       : Node_Id;
6614       Comp_List     : Node_Id;
6615       Discr         : Entity_Id;
6616       Discr_Val     : Node_Id;
6617
6618       Report_Errors : Boolean;
6619       pragma Warnings (Off, Report_Errors);
6620
6621    begin
6622       if Serious_Errors_Detected > 0 then
6623          return False;
6624       end if;
6625
6626       if Is_Record_Type (Typ)
6627         and then Nkind (Parent (Typ)) = N_Full_Type_Declaration
6628         and then Nkind (Type_Definition (Parent (Typ))) = N_Record_Definition
6629       then
6630          Comp_List := Component_List (Type_Definition (Parent (Typ)));
6631
6632          Discr := First_Discriminant (Typ);
6633          while Present (Discr) loop
6634             if Nkind (Parent (Discr)) = N_Discriminant_Specification then
6635                Discr_Val := Expression (Parent (Discr));
6636
6637                if Present (Discr_Val)
6638                  and then Is_OK_Static_Expression (Discr_Val)
6639                then
6640                   Append_To (Constraints,
6641                     Make_Component_Association (Loc,
6642                       Choices    => New_List (New_Occurrence_Of (Discr, Loc)),
6643                       Expression => New_Copy (Discr_Val)));
6644                else
6645                   return False;
6646                end if;
6647             else
6648                return False;
6649             end if;
6650
6651             Next_Discriminant (Discr);
6652          end loop;
6653
6654          Gather_Components
6655            (Typ           => Typ,
6656             Comp_List     => Comp_List,
6657             Governed_By   => Constraints,
6658             Into          => Components,
6659             Report_Errors => Report_Errors);
6660
6661          --  Check that each component present is fully initialized
6662
6663          Comp_Elmt := First_Elmt (Components);
6664          while Present (Comp_Elmt) loop
6665             Comp_Id := Node (Comp_Elmt);
6666
6667             if Ekind (Comp_Id) = E_Component
6668               and then (No (Parent (Comp_Id))
6669                          or else No (Expression (Parent (Comp_Id))))
6670               and then not Is_Fully_Initialized_Type (Etype (Comp_Id))
6671             then
6672                return False;
6673             end if;
6674
6675             Next_Elmt (Comp_Elmt);
6676          end loop;
6677
6678          return True;
6679
6680       elsif Is_Private_Type (Typ) then
6681          declare
6682             U : constant Entity_Id := Underlying_Type (Typ);
6683
6684          begin
6685             if No (U) then
6686                return False;
6687             else
6688                return Is_Fully_Initialized_Variant (U);
6689             end if;
6690          end;
6691       else
6692          return False;
6693       end if;
6694    end Is_Fully_Initialized_Variant;
6695
6696    ------------
6697    -- Is_LHS --
6698    ------------
6699
6700    --  We seem to have a lot of overlapping functions that do similar things
6701    --  (testing for left hand sides or lvalues???). Anyway, since this one is
6702    --  purely syntactic, it should be in Sem_Aux I would think???
6703
6704    function Is_LHS (N : Node_Id) return Boolean is
6705       P : constant Node_Id := Parent (N);
6706
6707    begin
6708       if Nkind (P) = N_Assignment_Statement then
6709          return Name (P) = N;
6710
6711       elsif
6712         Nkind_In (P, N_Indexed_Component, N_Selected_Component, N_Slice)
6713       then
6714          return N = Prefix (P) and then Is_LHS (P);
6715
6716       else
6717          return False;
6718       end if;
6719    end Is_LHS;
6720
6721    ----------------------------
6722    -- Is_Inherited_Operation --
6723    ----------------------------
6724
6725    function Is_Inherited_Operation (E : Entity_Id) return Boolean is
6726       Kind : constant Node_Kind := Nkind (Parent (E));
6727    begin
6728       pragma Assert (Is_Overloadable (E));
6729       return Kind = N_Full_Type_Declaration
6730         or else Kind = N_Private_Extension_Declaration
6731         or else Kind = N_Subtype_Declaration
6732         or else (Ekind (E) = E_Enumeration_Literal
6733                   and then Is_Derived_Type (Etype (E)));
6734    end Is_Inherited_Operation;
6735
6736    -----------------------------
6737    -- Is_Library_Level_Entity --
6738    -----------------------------
6739
6740    function Is_Library_Level_Entity (E : Entity_Id) return Boolean is
6741    begin
6742       --  The following is a small optimization, and it also properly handles
6743       --  discriminals, which in task bodies might appear in expressions before
6744       --  the corresponding procedure has been created, and which therefore do
6745       --  not have an assigned scope.
6746
6747       if Is_Formal (E) then
6748          return False;
6749       end if;
6750
6751       --  Normal test is simply that the enclosing dynamic scope is Standard
6752
6753       return Enclosing_Dynamic_Scope (E) = Standard_Standard;
6754    end Is_Library_Level_Entity;
6755
6756    ---------------------------------
6757    -- Is_Local_Variable_Reference --
6758    ---------------------------------
6759
6760    function Is_Local_Variable_Reference (Expr : Node_Id) return Boolean is
6761    begin
6762       if not Is_Entity_Name (Expr) then
6763          return False;
6764
6765       else
6766          declare
6767             Ent : constant Entity_Id := Entity (Expr);
6768             Sub : constant Entity_Id := Enclosing_Subprogram (Ent);
6769          begin
6770             if not Ekind_In (Ent, E_Variable, E_In_Out_Parameter) then
6771                return False;
6772             else
6773                return Present (Sub) and then Sub = Current_Subprogram;
6774             end if;
6775          end;
6776       end if;
6777    end Is_Local_Variable_Reference;
6778
6779    -------------------------
6780    -- Is_Object_Reference --
6781    -------------------------
6782
6783    function Is_Object_Reference (N : Node_Id) return Boolean is
6784    begin
6785       if Is_Entity_Name (N) then
6786          return Present (Entity (N)) and then Is_Object (Entity (N));
6787
6788       else
6789          case Nkind (N) is
6790             when N_Indexed_Component | N_Slice =>
6791                return
6792                  Is_Object_Reference (Prefix (N))
6793                    or else Is_Access_Type (Etype (Prefix (N)));
6794
6795             --  In Ada95, a function call is a constant object; a procedure
6796             --  call is not.
6797
6798             when N_Function_Call =>
6799                return Etype (N) /= Standard_Void_Type;
6800
6801             --  A reference to the stream attribute Input is a function call
6802
6803             when N_Attribute_Reference =>
6804                return Attribute_Name (N) = Name_Input;
6805
6806             when N_Selected_Component =>
6807                return
6808                  Is_Object_Reference (Selector_Name (N))
6809                    and then
6810                      (Is_Object_Reference (Prefix (N))
6811                         or else Is_Access_Type (Etype (Prefix (N))));
6812
6813             when N_Explicit_Dereference =>
6814                return True;
6815
6816             --  A view conversion of a tagged object is an object reference
6817
6818             when N_Type_Conversion =>
6819                return Is_Tagged_Type (Etype (Subtype_Mark (N)))
6820                  and then Is_Tagged_Type (Etype (Expression (N)))
6821                  and then Is_Object_Reference (Expression (N));
6822
6823             --  An unchecked type conversion is considered to be an object if
6824             --  the operand is an object (this construction arises only as a
6825             --  result of expansion activities).
6826
6827             when N_Unchecked_Type_Conversion =>
6828                return True;
6829
6830             when others =>
6831                return False;
6832          end case;
6833       end if;
6834    end Is_Object_Reference;
6835
6836    -----------------------------------
6837    -- Is_OK_Variable_For_Out_Formal --
6838    -----------------------------------
6839
6840    function Is_OK_Variable_For_Out_Formal (AV : Node_Id) return Boolean is
6841    begin
6842       Note_Possible_Modification (AV, Sure => True);
6843
6844       --  We must reject parenthesized variable names. The check for
6845       --  Comes_From_Source is present because there are currently
6846       --  cases where the compiler violates this rule (e.g. passing
6847       --  a task object to its controlled Initialize routine).
6848
6849       if Paren_Count (AV) > 0 and then Comes_From_Source (AV) then
6850          return False;
6851
6852       --  A variable is always allowed
6853
6854       elsif Is_Variable (AV) then
6855          return True;
6856
6857       --  Unchecked conversions are allowed only if they come from the
6858       --  generated code, which sometimes uses unchecked conversions for out
6859       --  parameters in cases where code generation is unaffected. We tell
6860       --  source unchecked conversions by seeing if they are rewrites of an
6861       --  original Unchecked_Conversion function call, or of an explicit
6862       --  conversion of a function call.
6863
6864       elsif Nkind (AV) = N_Unchecked_Type_Conversion then
6865          if Nkind (Original_Node (AV)) = N_Function_Call then
6866             return False;
6867
6868          elsif Comes_From_Source (AV)
6869            and then Nkind (Original_Node (Expression (AV))) = N_Function_Call
6870          then
6871             return False;
6872
6873          elsif Nkind (Original_Node (AV)) = N_Type_Conversion then
6874             return Is_OK_Variable_For_Out_Formal (Expression (AV));
6875
6876          else
6877             return True;
6878          end if;
6879
6880       --  Normal type conversions are allowed if argument is a variable
6881
6882       elsif Nkind (AV) = N_Type_Conversion then
6883          if Is_Variable (Expression (AV))
6884            and then Paren_Count (Expression (AV)) = 0
6885          then
6886             Note_Possible_Modification (Expression (AV), Sure => True);
6887             return True;
6888
6889          --  We also allow a non-parenthesized expression that raises
6890          --  constraint error if it rewrites what used to be a variable
6891
6892          elsif Raises_Constraint_Error (Expression (AV))
6893             and then Paren_Count (Expression (AV)) = 0
6894             and then Is_Variable (Original_Node (Expression (AV)))
6895          then
6896             return True;
6897
6898          --  Type conversion of something other than a variable
6899
6900          else
6901             return False;
6902          end if;
6903
6904       --  If this node is rewritten, then test the original form, if that is
6905       --  OK, then we consider the rewritten node OK (for example, if the
6906       --  original node is a conversion, then Is_Variable will not be true
6907       --  but we still want to allow the conversion if it converts a variable).
6908
6909       elsif Original_Node (AV) /= AV then
6910          return Is_OK_Variable_For_Out_Formal (Original_Node (AV));
6911
6912       --  All other non-variables are rejected
6913
6914       else
6915          return False;
6916       end if;
6917    end Is_OK_Variable_For_Out_Formal;
6918
6919    -----------------------------------
6920    -- Is_Partially_Initialized_Type --
6921    -----------------------------------
6922
6923    function Is_Partially_Initialized_Type
6924      (Typ              : Entity_Id;
6925       Include_Implicit : Boolean := True) return Boolean
6926    is
6927    begin
6928       if Is_Scalar_Type (Typ) then
6929          return False;
6930
6931       elsif Is_Access_Type (Typ) then
6932          return Include_Implicit;
6933
6934       elsif Is_Array_Type (Typ) then
6935
6936          --  If component type is partially initialized, so is array type
6937
6938          if Is_Partially_Initialized_Type
6939               (Component_Type (Typ), Include_Implicit)
6940          then
6941             return True;
6942
6943          --  Otherwise we are only partially initialized if we are fully
6944          --  initialized (this is the empty array case, no point in us
6945          --  duplicating that code here).
6946
6947          else
6948             return Is_Fully_Initialized_Type (Typ);
6949          end if;
6950
6951       elsif Is_Record_Type (Typ) then
6952
6953          --  A discriminated type is always partially initialized if in
6954          --  all mode
6955
6956          if Has_Discriminants (Typ) and then Include_Implicit then
6957             return True;
6958
6959          --  A tagged type is always partially initialized
6960
6961          elsif Is_Tagged_Type (Typ) then
6962             return True;
6963
6964          --  Case of non-discriminated record
6965
6966          else
6967             declare
6968                Ent : Entity_Id;
6969
6970                Component_Present : Boolean := False;
6971                --  Set True if at least one component is present. If no
6972                --  components are present, then record type is fully
6973                --  initialized (another odd case, like the null array).
6974
6975             begin
6976                --  Loop through components
6977
6978                Ent := First_Entity (Typ);
6979                while Present (Ent) loop
6980                   if Ekind (Ent) = E_Component then
6981                      Component_Present := True;
6982
6983                      --  If a component has an initialization expression then
6984                      --  the enclosing record type is partially initialized
6985
6986                      if Present (Parent (Ent))
6987                        and then Present (Expression (Parent (Ent)))
6988                      then
6989                         return True;
6990
6991                      --  If a component is of a type which is itself partially
6992                      --  initialized, then the enclosing record type is also.
6993
6994                      elsif Is_Partially_Initialized_Type
6995                              (Etype (Ent), Include_Implicit)
6996                      then
6997                         return True;
6998                      end if;
6999                   end if;
7000
7001                   Next_Entity (Ent);
7002                end loop;
7003
7004                --  No initialized components found. If we found any components
7005                --  they were all uninitialized so the result is false.
7006
7007                if Component_Present then
7008                   return False;
7009
7010                --  But if we found no components, then all the components are
7011                --  initialized so we consider the type to be initialized.
7012
7013                else
7014                   return True;
7015                end if;
7016             end;
7017          end if;
7018
7019       --  Concurrent types are always fully initialized
7020
7021       elsif Is_Concurrent_Type (Typ) then
7022          return True;
7023
7024       --  For a private type, go to underlying type. If there is no underlying
7025       --  type then just assume this partially initialized. Not clear if this
7026       --  can happen in a non-error case, but no harm in testing for this.
7027
7028       elsif Is_Private_Type (Typ) then
7029          declare
7030             U : constant Entity_Id := Underlying_Type (Typ);
7031          begin
7032             if No (U) then
7033                return True;
7034             else
7035                return Is_Partially_Initialized_Type (U, Include_Implicit);
7036             end if;
7037          end;
7038
7039       --  For any other type (are there any?) assume partially initialized
7040
7041       else
7042          return True;
7043       end if;
7044    end Is_Partially_Initialized_Type;
7045
7046    ------------------------------------
7047    -- Is_Potentially_Persistent_Type --
7048    ------------------------------------
7049
7050    function Is_Potentially_Persistent_Type (T : Entity_Id) return Boolean is
7051       Comp : Entity_Id;
7052       Indx : Node_Id;
7053
7054    begin
7055       --  For private type, test corresponding full type
7056
7057       if Is_Private_Type (T) then
7058          return Is_Potentially_Persistent_Type (Full_View (T));
7059
7060       --  Scalar types are potentially persistent
7061
7062       elsif Is_Scalar_Type (T) then
7063          return True;
7064
7065       --  Record type is potentially persistent if not tagged and the types of
7066       --  all it components are potentially persistent, and no component has
7067       --  an initialization expression.
7068
7069       elsif Is_Record_Type (T)
7070         and then not Is_Tagged_Type (T)
7071         and then not Is_Partially_Initialized_Type (T)
7072       then
7073          Comp := First_Component (T);
7074          while Present (Comp) loop
7075             if not Is_Potentially_Persistent_Type (Etype (Comp)) then
7076                return False;
7077             else
7078                Next_Entity (Comp);
7079             end if;
7080          end loop;
7081
7082          return True;
7083
7084       --  Array type is potentially persistent if its component type is
7085       --  potentially persistent and if all its constraints are static.
7086
7087       elsif Is_Array_Type (T) then
7088          if not Is_Potentially_Persistent_Type (Component_Type (T)) then
7089             return False;
7090          end if;
7091
7092          Indx := First_Index (T);
7093          while Present (Indx) loop
7094             if not Is_OK_Static_Subtype (Etype (Indx)) then
7095                return False;
7096             else
7097                Next_Index (Indx);
7098             end if;
7099          end loop;
7100
7101          return True;
7102
7103       --  All other types are not potentially persistent
7104
7105       else
7106          return False;
7107       end if;
7108    end Is_Potentially_Persistent_Type;
7109
7110    ---------------------------------
7111    -- Is_Protected_Self_Reference --
7112    ---------------------------------
7113
7114    function Is_Protected_Self_Reference (N : Node_Id) return Boolean is
7115
7116       function In_Access_Definition (N : Node_Id) return Boolean;
7117       --  Returns true if N belongs to an access definition
7118
7119       --------------------------
7120       -- In_Access_Definition --
7121       --------------------------
7122
7123       function In_Access_Definition (N : Node_Id) return Boolean is
7124          P : Node_Id;
7125
7126       begin
7127          P := Parent (N);
7128          while Present (P) loop
7129             if Nkind (P) = N_Access_Definition then
7130                return True;
7131             end if;
7132
7133             P := Parent (P);
7134          end loop;
7135
7136          return False;
7137       end In_Access_Definition;
7138
7139    --  Start of processing for Is_Protected_Self_Reference
7140
7141    begin
7142       --  Verify that prefix is analyzed and has the proper form. Note that
7143       --  the attributes Elab_Spec, Elab_Body, and UET_Address, which also
7144       --  produce the address of an entity, do not analyze their prefix
7145       --  because they denote entities that are not necessarily visible.
7146       --  Neither of them can apply to a protected type.
7147
7148       return Ada_Version >= Ada_2005
7149         and then Is_Entity_Name (N)
7150         and then Present (Entity (N))
7151         and then Is_Protected_Type (Entity (N))
7152         and then In_Open_Scopes (Entity (N))
7153         and then not In_Access_Definition (N);
7154    end Is_Protected_Self_Reference;
7155
7156    -----------------------------
7157    -- Is_RCI_Pkg_Spec_Or_Body --
7158    -----------------------------
7159
7160    function Is_RCI_Pkg_Spec_Or_Body (Cunit : Node_Id) return Boolean is
7161
7162       function Is_RCI_Pkg_Decl_Cunit (Cunit : Node_Id) return Boolean;
7163       --  Return True if the unit of Cunit is an RCI package declaration
7164
7165       ---------------------------
7166       -- Is_RCI_Pkg_Decl_Cunit --
7167       ---------------------------
7168
7169       function Is_RCI_Pkg_Decl_Cunit (Cunit : Node_Id) return Boolean is
7170          The_Unit : constant Node_Id := Unit (Cunit);
7171
7172       begin
7173          if Nkind (The_Unit) /= N_Package_Declaration then
7174             return False;
7175          end if;
7176
7177          return Is_Remote_Call_Interface (Defining_Entity (The_Unit));
7178       end Is_RCI_Pkg_Decl_Cunit;
7179
7180    --  Start of processing for Is_RCI_Pkg_Spec_Or_Body
7181
7182    begin
7183       return Is_RCI_Pkg_Decl_Cunit (Cunit)
7184         or else
7185          (Nkind (Unit (Cunit)) = N_Package_Body
7186            and then Is_RCI_Pkg_Decl_Cunit (Library_Unit (Cunit)));
7187    end Is_RCI_Pkg_Spec_Or_Body;
7188
7189    -----------------------------------------
7190    -- Is_Remote_Access_To_Class_Wide_Type --
7191    -----------------------------------------
7192
7193    function Is_Remote_Access_To_Class_Wide_Type
7194      (E : Entity_Id) return Boolean
7195    is
7196    begin
7197       --  A remote access to class-wide type is a general access to object type
7198       --  declared in the visible part of a Remote_Types or Remote_Call_
7199       --  Interface unit.
7200
7201       return Ekind (E) = E_General_Access_Type
7202         and then (Is_Remote_Call_Interface (E) or else Is_Remote_Types (E));
7203    end Is_Remote_Access_To_Class_Wide_Type;
7204
7205    -----------------------------------------
7206    -- Is_Remote_Access_To_Subprogram_Type --
7207    -----------------------------------------
7208
7209    function Is_Remote_Access_To_Subprogram_Type
7210      (E : Entity_Id) return Boolean
7211    is
7212    begin
7213       return (Ekind (E) = E_Access_Subprogram_Type
7214                 or else (Ekind (E) = E_Record_Type
7215                            and then Present (Corresponding_Remote_Type (E))))
7216         and then (Is_Remote_Call_Interface (E) or else Is_Remote_Types (E));
7217    end Is_Remote_Access_To_Subprogram_Type;
7218
7219    --------------------
7220    -- Is_Remote_Call --
7221    --------------------
7222
7223    function Is_Remote_Call (N : Node_Id) return Boolean is
7224    begin
7225       if Nkind (N) /= N_Procedure_Call_Statement
7226         and then Nkind (N) /= N_Function_Call
7227       then
7228          --  An entry call cannot be remote
7229
7230          return False;
7231
7232       elsif Nkind (Name (N)) in N_Has_Entity
7233         and then Is_Remote_Call_Interface (Entity (Name (N)))
7234       then
7235          --  A subprogram declared in the spec of a RCI package is remote
7236
7237          return True;
7238
7239       elsif Nkind (Name (N)) = N_Explicit_Dereference
7240         and then Is_Remote_Access_To_Subprogram_Type
7241                    (Etype (Prefix (Name (N))))
7242       then
7243          --  The dereference of a RAS is a remote call
7244
7245          return True;
7246
7247       elsif Present (Controlling_Argument (N))
7248         and then Is_Remote_Access_To_Class_Wide_Type
7249           (Etype (Controlling_Argument (N)))
7250       then
7251          --  Any primitive operation call with a controlling argument of
7252          --  a RACW type is a remote call.
7253
7254          return True;
7255       end if;
7256
7257       --  All other calls are local calls
7258
7259       return False;
7260    end Is_Remote_Call;
7261
7262    ----------------------
7263    -- Is_Renamed_Entry --
7264    ----------------------
7265
7266    function Is_Renamed_Entry (Proc_Nam : Entity_Id) return Boolean is
7267       Orig_Node : Node_Id := Empty;
7268       Subp_Decl : Node_Id := Parent (Parent (Proc_Nam));
7269
7270       function Is_Entry (Nam : Node_Id) return Boolean;
7271       --  Determine whether Nam is an entry. Traverse selectors if there are
7272       --  nested selected components.
7273
7274       --------------
7275       -- Is_Entry --
7276       --------------
7277
7278       function Is_Entry (Nam : Node_Id) return Boolean is
7279       begin
7280          if Nkind (Nam) = N_Selected_Component then
7281             return Is_Entry (Selector_Name (Nam));
7282          end if;
7283
7284          return Ekind (Entity (Nam)) = E_Entry;
7285       end Is_Entry;
7286
7287    --  Start of processing for Is_Renamed_Entry
7288
7289    begin
7290       if Present (Alias (Proc_Nam)) then
7291          Subp_Decl := Parent (Parent (Alias (Proc_Nam)));
7292       end if;
7293
7294       --  Look for a rewritten subprogram renaming declaration
7295
7296       if Nkind (Subp_Decl) = N_Subprogram_Declaration
7297         and then Present (Original_Node (Subp_Decl))
7298       then
7299          Orig_Node := Original_Node (Subp_Decl);
7300       end if;
7301
7302       --  The rewritten subprogram is actually an entry
7303
7304       if Present (Orig_Node)
7305         and then Nkind (Orig_Node) = N_Subprogram_Renaming_Declaration
7306         and then Is_Entry (Name (Orig_Node))
7307       then
7308          return True;
7309       end if;
7310
7311       return False;
7312    end Is_Renamed_Entry;
7313
7314    ----------------------
7315    -- Is_Selector_Name --
7316    ----------------------
7317
7318    function Is_Selector_Name (N : Node_Id) return Boolean is
7319    begin
7320       if not Is_List_Member (N) then
7321          declare
7322             P : constant Node_Id   := Parent (N);
7323             K : constant Node_Kind := Nkind (P);
7324          begin
7325             return
7326               (K = N_Expanded_Name          or else
7327                K = N_Generic_Association    or else
7328                K = N_Parameter_Association  or else
7329                K = N_Selected_Component)
7330               and then Selector_Name (P) = N;
7331          end;
7332
7333       else
7334          declare
7335             L : constant List_Id := List_Containing (N);
7336             P : constant Node_Id := Parent (L);
7337          begin
7338             return (Nkind (P) = N_Discriminant_Association
7339                      and then Selector_Names (P) = L)
7340               or else
7341                    (Nkind (P) = N_Component_Association
7342                      and then Choices (P) = L);
7343          end;
7344       end if;
7345    end Is_Selector_Name;
7346
7347    ------------------
7348    -- Is_Statement --
7349    ------------------
7350
7351    function Is_Statement (N : Node_Id) return Boolean is
7352    begin
7353       return
7354         Nkind (N) in N_Statement_Other_Than_Procedure_Call
7355           or else Nkind (N) = N_Procedure_Call_Statement;
7356    end Is_Statement;
7357
7358    ---------------------------------
7359    -- Is_Synchronized_Tagged_Type --
7360    ---------------------------------
7361
7362    function Is_Synchronized_Tagged_Type (E : Entity_Id) return Boolean is
7363       Kind : constant Entity_Kind := Ekind (Base_Type (E));
7364
7365    begin
7366       --  A task or protected type derived from an interface is a tagged type.
7367       --  Such a tagged type is called a synchronized tagged type, as are
7368       --  synchronized interfaces and private extensions whose declaration
7369       --  includes the reserved word synchronized.
7370
7371       return (Is_Tagged_Type (E)
7372                 and then (Kind = E_Task_Type
7373                            or else Kind = E_Protected_Type))
7374             or else
7375              (Is_Interface (E)
7376                 and then Is_Synchronized_Interface (E))
7377             or else
7378              (Ekind (E) = E_Record_Type_With_Private
7379                 and then Nkind (Parent (E)) = N_Private_Extension_Declaration
7380                 and then (Synchronized_Present (Parent (E))
7381                            or else Is_Synchronized_Interface (Etype (E))));
7382    end Is_Synchronized_Tagged_Type;
7383
7384    -----------------
7385    -- Is_Transfer --
7386    -----------------
7387
7388    function Is_Transfer (N : Node_Id) return Boolean is
7389       Kind : constant Node_Kind := Nkind (N);
7390
7391    begin
7392       if Kind = N_Simple_Return_Statement
7393            or else
7394          Kind = N_Extended_Return_Statement
7395            or else
7396          Kind = N_Goto_Statement
7397            or else
7398          Kind = N_Raise_Statement
7399            or else
7400          Kind = N_Requeue_Statement
7401       then
7402          return True;
7403
7404       elsif (Kind = N_Exit_Statement or else Kind in N_Raise_xxx_Error)
7405         and then No (Condition (N))
7406       then
7407          return True;
7408
7409       elsif Kind = N_Procedure_Call_Statement
7410         and then Is_Entity_Name (Name (N))
7411         and then Present (Entity (Name (N)))
7412         and then No_Return (Entity (Name (N)))
7413       then
7414          return True;
7415
7416       elsif Nkind (Original_Node (N)) = N_Raise_Statement then
7417          return True;
7418
7419       else
7420          return False;
7421       end if;
7422    end Is_Transfer;
7423
7424    -------------
7425    -- Is_True --
7426    -------------
7427
7428    function Is_True (U : Uint) return Boolean is
7429    begin
7430       return (U /= 0);
7431    end Is_True;
7432
7433    -------------------------------
7434    -- Is_Universal_Numeric_Type --
7435    -------------------------------
7436
7437    function Is_Universal_Numeric_Type (T : Entity_Id) return Boolean is
7438    begin
7439       return T = Universal_Integer or else T = Universal_Real;
7440    end Is_Universal_Numeric_Type;
7441
7442    -------------------
7443    -- Is_Value_Type --
7444    -------------------
7445
7446    function Is_Value_Type (T : Entity_Id) return Boolean is
7447    begin
7448       return VM_Target = CLI_Target
7449         and then Nkind (T) in N_Has_Chars
7450         and then Chars (T) /= No_Name
7451         and then Get_Name_String (Chars (T)) = "valuetype";
7452    end Is_Value_Type;
7453
7454    ---------------------
7455    -- Is_VMS_Operator --
7456    ---------------------
7457
7458    function Is_VMS_Operator (Op : Entity_Id) return Boolean is
7459    begin
7460       --  The VMS operators are declared in a child of System that is loaded
7461       --  through pragma Extend_System. In some rare cases a program is run
7462       --  with this extension but without indicating that the target is VMS.
7463
7464       return Ekind (Op) = E_Function
7465         and then Is_Intrinsic_Subprogram (Op)
7466         and then
7467           ((Present_System_Aux
7468             and then Scope (Op) = System_Aux_Id)
7469            or else
7470            (True_VMS_Target
7471              and then Scope (Scope (Op)) = RTU_Entity (System)));
7472    end Is_VMS_Operator;
7473
7474    -----------------
7475    -- Is_Variable --
7476    -----------------
7477
7478    function Is_Variable (N : Node_Id) return Boolean is
7479
7480       Orig_Node : constant Node_Id := Original_Node (N);
7481       --  We do the test on the original node, since this is basically a test
7482       --  of syntactic categories, so it must not be disturbed by whatever
7483       --  rewriting might have occurred. For example, an aggregate, which is
7484       --  certainly NOT a variable, could be turned into a variable by
7485       --  expansion.
7486
7487       function In_Protected_Function (E : Entity_Id) return Boolean;
7488       --  Within a protected function, the private components of the enclosing
7489       --  protected type are constants. A function nested within a (protected)
7490       --  procedure is not itself protected.
7491
7492       function Is_Variable_Prefix (P : Node_Id) return Boolean;
7493       --  Prefixes can involve implicit dereferences, in which case we must
7494       --  test for the case of a reference of a constant access type, which can
7495       --  can never be a variable.
7496
7497       ---------------------------
7498       -- In_Protected_Function --
7499       ---------------------------
7500
7501       function In_Protected_Function (E : Entity_Id) return Boolean is
7502          Prot : constant Entity_Id := Scope (E);
7503          S    : Entity_Id;
7504
7505       begin
7506          if not Is_Protected_Type (Prot) then
7507             return False;
7508          else
7509             S := Current_Scope;
7510             while Present (S) and then S /= Prot loop
7511                if Ekind (S) = E_Function and then Scope (S) = Prot then
7512                   return True;
7513                end if;
7514
7515                S := Scope (S);
7516             end loop;
7517
7518             return False;
7519          end if;
7520       end In_Protected_Function;
7521
7522       ------------------------
7523       -- Is_Variable_Prefix --
7524       ------------------------
7525
7526       function Is_Variable_Prefix (P : Node_Id) return Boolean is
7527       begin
7528          if Is_Access_Type (Etype (P)) then
7529             return not Is_Access_Constant (Root_Type (Etype (P)));
7530
7531          --  For the case of an indexed component whose prefix has a packed
7532          --  array type, the prefix has been rewritten into a type conversion.
7533          --  Determine variable-ness from the converted expression.
7534
7535          elsif Nkind (P) = N_Type_Conversion
7536            and then not Comes_From_Source (P)
7537            and then Is_Array_Type (Etype (P))
7538            and then Is_Packed (Etype (P))
7539          then
7540             return Is_Variable (Expression (P));
7541
7542          else
7543             return Is_Variable (P);
7544          end if;
7545       end Is_Variable_Prefix;
7546
7547    --  Start of processing for Is_Variable
7548
7549    begin
7550       --  Definitely OK if Assignment_OK is set. Since this is something that
7551       --  only gets set for expanded nodes, the test is on N, not Orig_Node.
7552
7553       if Nkind (N) in N_Subexpr and then Assignment_OK (N) then
7554          return True;
7555
7556       --  Normally we go to the original node, but there is one exception where
7557       --  we use the rewritten node, namely when it is an explicit dereference.
7558       --  The generated code may rewrite a prefix which is an access type with
7559       --  an explicit dereference. The dereference is a variable, even though
7560       --  the original node may not be (since it could be a constant of the
7561       --  access type).
7562
7563       --  In Ada 2005 we have a further case to consider: the prefix may be a
7564       --  function call given in prefix notation. The original node appears to
7565       --  be a selected component, but we need to examine the call.
7566
7567       elsif Nkind (N) = N_Explicit_Dereference
7568         and then Nkind (Orig_Node) /= N_Explicit_Dereference
7569         and then Present (Etype (Orig_Node))
7570         and then Is_Access_Type (Etype (Orig_Node))
7571       then
7572          --  Note that if the prefix is an explicit dereference that does not
7573          --  come from source, we must check for a rewritten function call in
7574          --  prefixed notation before other forms of rewriting, to prevent a
7575          --  compiler crash.
7576
7577          return
7578            (Nkind (Orig_Node) = N_Function_Call
7579              and then not Is_Access_Constant (Etype (Prefix (N))))
7580            or else
7581              Is_Variable_Prefix (Original_Node (Prefix (N)));
7582
7583       --  A function call is never a variable
7584
7585       elsif Nkind (N) = N_Function_Call then
7586          return False;
7587
7588       --  All remaining checks use the original node
7589
7590       elsif Is_Entity_Name (Orig_Node)
7591         and then Present (Entity (Orig_Node))
7592       then
7593          declare
7594             E : constant Entity_Id := Entity (Orig_Node);
7595             K : constant Entity_Kind := Ekind (E);
7596
7597          begin
7598             return (K = E_Variable
7599                       and then Nkind (Parent (E)) /= N_Exception_Handler)
7600               or else  (K = E_Component
7601                           and then not In_Protected_Function (E))
7602               or else  K = E_Out_Parameter
7603               or else  K = E_In_Out_Parameter
7604               or else  K = E_Generic_In_Out_Parameter
7605
7606                --  Current instance of type:
7607
7608               or else (Is_Type (E) and then In_Open_Scopes (E))
7609               or else (Is_Incomplete_Or_Private_Type (E)
7610                         and then In_Open_Scopes (Full_View (E)));
7611          end;
7612
7613       else
7614          case Nkind (Orig_Node) is
7615             when N_Indexed_Component | N_Slice =>
7616                return Is_Variable_Prefix (Prefix (Orig_Node));
7617
7618             when N_Selected_Component =>
7619                return Is_Variable_Prefix (Prefix (Orig_Node))
7620                  and then Is_Variable (Selector_Name (Orig_Node));
7621
7622             --  For an explicit dereference, the type of the prefix cannot
7623             --  be an access to constant or an access to subprogram.
7624
7625             when N_Explicit_Dereference =>
7626                declare
7627                   Typ : constant Entity_Id := Etype (Prefix (Orig_Node));
7628                begin
7629                   return Is_Access_Type (Typ)
7630                     and then not Is_Access_Constant (Root_Type (Typ))
7631                     and then Ekind (Typ) /= E_Access_Subprogram_Type;
7632                end;
7633
7634             --  The type conversion is the case where we do not deal with the
7635             --  context dependent special case of an actual parameter. Thus
7636             --  the type conversion is only considered a variable for the
7637             --  purposes of this routine if the target type is tagged. However,
7638             --  a type conversion is considered to be a variable if it does not
7639             --  come from source (this deals for example with the conversions
7640             --  of expressions to their actual subtypes).
7641
7642             when N_Type_Conversion =>
7643                return Is_Variable (Expression (Orig_Node))
7644                  and then
7645                    (not Comes_From_Source (Orig_Node)
7646                       or else
7647                         (Is_Tagged_Type (Etype (Subtype_Mark (Orig_Node)))
7648                           and then
7649                          Is_Tagged_Type (Etype (Expression (Orig_Node)))));
7650
7651             --  GNAT allows an unchecked type conversion as a variable. This
7652             --  only affects the generation of internal expanded code, since
7653             --  calls to instantiations of Unchecked_Conversion are never
7654             --  considered variables (since they are function calls).
7655             --  This is also true for expression actions.
7656
7657             when N_Unchecked_Type_Conversion =>
7658                return Is_Variable (Expression (Orig_Node));
7659
7660             when others =>
7661                return False;
7662          end case;
7663       end if;
7664    end Is_Variable;
7665
7666    ---------------------------
7667    -- Is_Visibly_Controlled --
7668    ---------------------------
7669
7670    function Is_Visibly_Controlled (T : Entity_Id) return Boolean is
7671       Root : constant Entity_Id := Root_Type (T);
7672    begin
7673       return Chars (Scope (Root)) = Name_Finalization
7674         and then Chars (Scope (Scope (Root))) = Name_Ada
7675         and then Scope (Scope (Scope (Root))) = Standard_Standard;
7676    end Is_Visibly_Controlled;
7677
7678    ------------------------
7679    -- Is_Volatile_Object --
7680    ------------------------
7681
7682    function Is_Volatile_Object (N : Node_Id) return Boolean is
7683
7684       function Object_Has_Volatile_Components (N : Node_Id) return Boolean;
7685       --  Determines if given object has volatile components
7686
7687       function Is_Volatile_Prefix (N : Node_Id) return Boolean;
7688       --  If prefix is an implicit dereference, examine designated type
7689
7690       ------------------------
7691       -- Is_Volatile_Prefix --
7692       ------------------------
7693
7694       function Is_Volatile_Prefix (N : Node_Id) return Boolean is
7695          Typ  : constant Entity_Id := Etype (N);
7696
7697       begin
7698          if Is_Access_Type (Typ) then
7699             declare
7700                Dtyp : constant Entity_Id := Designated_Type (Typ);
7701
7702             begin
7703                return Is_Volatile (Dtyp)
7704                  or else Has_Volatile_Components (Dtyp);
7705             end;
7706
7707          else
7708             return Object_Has_Volatile_Components (N);
7709          end if;
7710       end Is_Volatile_Prefix;
7711
7712       ------------------------------------
7713       -- Object_Has_Volatile_Components --
7714       ------------------------------------
7715
7716       function Object_Has_Volatile_Components (N : Node_Id) return Boolean is
7717          Typ : constant Entity_Id := Etype (N);
7718
7719       begin
7720          if Is_Volatile (Typ)
7721            or else Has_Volatile_Components (Typ)
7722          then
7723             return True;
7724
7725          elsif Is_Entity_Name (N)
7726            and then (Has_Volatile_Components (Entity (N))
7727                       or else Is_Volatile (Entity (N)))
7728          then
7729             return True;
7730
7731          elsif Nkind (N) = N_Indexed_Component
7732            or else Nkind (N) = N_Selected_Component
7733          then
7734             return Is_Volatile_Prefix (Prefix (N));
7735
7736          else
7737             return False;
7738          end if;
7739       end Object_Has_Volatile_Components;
7740
7741    --  Start of processing for Is_Volatile_Object
7742
7743    begin
7744       if Is_Volatile (Etype (N))
7745         or else (Is_Entity_Name (N) and then Is_Volatile (Entity (N)))
7746       then
7747          return True;
7748
7749       elsif Nkind (N) = N_Indexed_Component
7750         or else Nkind (N) = N_Selected_Component
7751       then
7752          return Is_Volatile_Prefix (Prefix (N));
7753
7754       else
7755          return False;
7756       end if;
7757    end Is_Volatile_Object;
7758
7759    -------------------------
7760    -- Kill_Current_Values --
7761    -------------------------
7762
7763    procedure Kill_Current_Values
7764      (Ent                  : Entity_Id;
7765       Last_Assignment_Only : Boolean := False)
7766    is
7767    begin
7768       --  ??? do we have to worry about clearing cached checks?
7769
7770       if Is_Assignable (Ent) then
7771          Set_Last_Assignment (Ent, Empty);
7772       end if;
7773
7774       if Is_Object (Ent) then
7775          if not Last_Assignment_Only then
7776             Kill_Checks (Ent);
7777             Set_Current_Value (Ent, Empty);
7778
7779             if not Can_Never_Be_Null (Ent) then
7780                Set_Is_Known_Non_Null (Ent, False);
7781             end if;
7782
7783             Set_Is_Known_Null (Ent, False);
7784
7785             --  Reset Is_Known_Valid unless type is always valid, or if we have
7786             --  a loop parameter (loop parameters are always valid, since their
7787             --  bounds are defined by the bounds given in the loop header).
7788
7789             if not Is_Known_Valid (Etype (Ent))
7790               and then Ekind (Ent) /= E_Loop_Parameter
7791             then
7792                Set_Is_Known_Valid (Ent, False);
7793             end if;
7794          end if;
7795       end if;
7796    end Kill_Current_Values;
7797
7798    procedure Kill_Current_Values (Last_Assignment_Only : Boolean := False) is
7799       S : Entity_Id;
7800
7801       procedure Kill_Current_Values_For_Entity_Chain (E : Entity_Id);
7802       --  Clear current value for entity E and all entities chained to E
7803
7804       ------------------------------------------
7805       -- Kill_Current_Values_For_Entity_Chain --
7806       ------------------------------------------
7807
7808       procedure Kill_Current_Values_For_Entity_Chain (E : Entity_Id) is
7809          Ent : Entity_Id;
7810       begin
7811          Ent := E;
7812          while Present (Ent) loop
7813             Kill_Current_Values (Ent, Last_Assignment_Only);
7814             Next_Entity (Ent);
7815          end loop;
7816       end Kill_Current_Values_For_Entity_Chain;
7817
7818    --  Start of processing for Kill_Current_Values
7819
7820    begin
7821       --  Kill all saved checks, a special case of killing saved values
7822
7823       if not Last_Assignment_Only then
7824          Kill_All_Checks;
7825       end if;
7826
7827       --  Loop through relevant scopes, which includes the current scope and
7828       --  any parent scopes if the current scope is a block or a package.
7829
7830       S := Current_Scope;
7831       Scope_Loop : loop
7832
7833          --  Clear current values of all entities in current scope
7834
7835          Kill_Current_Values_For_Entity_Chain (First_Entity (S));
7836
7837          --  If scope is a package, also clear current values of all
7838          --  private entities in the scope.
7839
7840          if Is_Package_Or_Generic_Package (S)
7841            or else Is_Concurrent_Type (S)
7842          then
7843             Kill_Current_Values_For_Entity_Chain (First_Private_Entity (S));
7844          end if;
7845
7846          --  If this is a not a subprogram, deal with parents
7847
7848          if not Is_Subprogram (S) then
7849             S := Scope (S);
7850             exit Scope_Loop when S = Standard_Standard;
7851          else
7852             exit Scope_Loop;
7853          end if;
7854       end loop Scope_Loop;
7855    end Kill_Current_Values;
7856
7857    --------------------------
7858    -- Kill_Size_Check_Code --
7859    --------------------------
7860
7861    procedure Kill_Size_Check_Code (E : Entity_Id) is
7862    begin
7863       if (Ekind (E) = E_Constant or else Ekind (E) = E_Variable)
7864         and then Present (Size_Check_Code (E))
7865       then
7866          Remove (Size_Check_Code (E));
7867          Set_Size_Check_Code (E, Empty);
7868       end if;
7869    end Kill_Size_Check_Code;
7870
7871    --------------------------
7872    -- Known_To_Be_Assigned --
7873    --------------------------
7874
7875    function Known_To_Be_Assigned (N : Node_Id) return Boolean is
7876       P : constant Node_Id := Parent (N);
7877
7878    begin
7879       case Nkind (P) is
7880
7881          --  Test left side of assignment
7882
7883          when N_Assignment_Statement =>
7884             return N = Name (P);
7885
7886             --  Function call arguments are never lvalues
7887
7888          when N_Function_Call =>
7889             return False;
7890
7891          --  Positional parameter for procedure or accept call
7892
7893          when N_Procedure_Call_Statement |
7894               N_Accept_Statement
7895           =>
7896             declare
7897                Proc : Entity_Id;
7898                Form : Entity_Id;
7899                Act  : Node_Id;
7900
7901             begin
7902                Proc := Get_Subprogram_Entity (P);
7903
7904                if No (Proc) then
7905                   return False;
7906                end if;
7907
7908                --  If we are not a list member, something is strange, so
7909                --  be conservative and return False.
7910
7911                if not Is_List_Member (N) then
7912                   return False;
7913                end if;
7914
7915                --  We are going to find the right formal by stepping forward
7916                --  through the formals, as we step backwards in the actuals.
7917
7918                Form := First_Formal (Proc);
7919                Act  := N;
7920                loop
7921                   --  If no formal, something is weird, so be conservative
7922                   --  and return False.
7923
7924                   if No (Form) then
7925                      return False;
7926                   end if;
7927
7928                   Prev (Act);
7929                   exit when No (Act);
7930                   Next_Formal (Form);
7931                end loop;
7932
7933                return Ekind (Form) /= E_In_Parameter;
7934             end;
7935
7936          --  Named parameter for procedure or accept call
7937
7938          when N_Parameter_Association =>
7939             declare
7940                Proc : Entity_Id;
7941                Form : Entity_Id;
7942
7943             begin
7944                Proc := Get_Subprogram_Entity (Parent (P));
7945
7946                if No (Proc) then
7947                   return False;
7948                end if;
7949
7950                --  Loop through formals to find the one that matches
7951
7952                Form := First_Formal (Proc);
7953                loop
7954                   --  If no matching formal, that's peculiar, some kind of
7955                   --  previous error, so return False to be conservative.
7956
7957                   if No (Form) then
7958                      return False;
7959                   end if;
7960
7961                   --  Else test for match
7962
7963                   if Chars (Form) = Chars (Selector_Name (P)) then
7964                      return Ekind (Form) /= E_In_Parameter;
7965                   end if;
7966
7967                   Next_Formal (Form);
7968                end loop;
7969             end;
7970
7971          --  Test for appearing in a conversion that itself appears
7972          --  in an lvalue context, since this should be an lvalue.
7973
7974          when N_Type_Conversion =>
7975             return Known_To_Be_Assigned (P);
7976
7977          --  All other references are definitely not known to be modifications
7978
7979          when others =>
7980             return False;
7981
7982       end case;
7983    end Known_To_Be_Assigned;
7984
7985    ---------------------------
7986    -- Last_Source_Statement --
7987    ---------------------------
7988
7989    function Last_Source_Statement (HSS : Node_Id) return Node_Id is
7990       N : Node_Id;
7991
7992    begin
7993       N := Last (Statements (HSS));
7994       while Present (N) loop
7995          exit when Comes_From_Source (N);
7996          Prev (N);
7997       end loop;
7998
7999       return N;
8000    end Last_Source_Statement;
8001
8002    ----------------------------------
8003    -- Matching_Static_Array_Bounds --
8004    ----------------------------------
8005
8006    function Matching_Static_Array_Bounds
8007      (L_Typ : Node_Id;
8008       R_Typ : Node_Id) return Boolean
8009    is
8010       L_Ndims : constant Nat := Number_Dimensions (L_Typ);
8011       R_Ndims : constant Nat := Number_Dimensions (R_Typ);
8012
8013       L_Index : Node_Id;
8014       R_Index : Node_Id;
8015       L_Low   : Node_Id;
8016       L_High  : Node_Id;
8017       L_Len   : Uint;
8018       R_Low   : Node_Id;
8019       R_High  : Node_Id;
8020       R_Len   : Uint;
8021
8022    begin
8023       if L_Ndims /= R_Ndims then
8024          return False;
8025       end if;
8026
8027       --  Unconstrained types do not have static bounds
8028
8029       if not Is_Constrained (L_Typ) or else not Is_Constrained (R_Typ) then
8030          return False;
8031       end if;
8032
8033       --  First treat specially the first dimension, as the lower bound and
8034       --  length of string literals are not stored like those of arrays.
8035
8036       if Ekind (L_Typ) = E_String_Literal_Subtype then
8037          L_Low := String_Literal_Low_Bound (L_Typ);
8038          L_Len := String_Literal_Length (L_Typ);
8039       else
8040          L_Index := First_Index (L_Typ);
8041          Get_Index_Bounds (L_Index, L_Low, L_High);
8042
8043          if         Is_OK_Static_Expression (L_Low)
8044            and then Is_OK_Static_Expression (L_High)
8045          then
8046             if Expr_Value (L_High) < Expr_Value (L_Low) then
8047                L_Len := Uint_0;
8048             else
8049                L_Len := (Expr_Value (L_High) - Expr_Value (L_Low)) + 1;
8050             end if;
8051          else
8052             return False;
8053          end if;
8054       end if;
8055
8056       if Ekind (R_Typ) = E_String_Literal_Subtype then
8057          R_Low := String_Literal_Low_Bound (R_Typ);
8058          R_Len := String_Literal_Length (R_Typ);
8059       else
8060          R_Index := First_Index (R_Typ);
8061          Get_Index_Bounds (R_Index, R_Low, R_High);
8062
8063          if         Is_OK_Static_Expression (R_Low)
8064            and then Is_OK_Static_Expression (R_High)
8065          then
8066             if Expr_Value (R_High) < Expr_Value (R_Low) then
8067                R_Len := Uint_0;
8068             else
8069                R_Len := (Expr_Value (R_High) - Expr_Value (R_Low)) + 1;
8070             end if;
8071          else
8072             return False;
8073          end if;
8074       end if;
8075
8076       if         Is_OK_Static_Expression (L_Low)
8077         and then Is_OK_Static_Expression (R_Low)
8078         and then Expr_Value (L_Low) = Expr_Value (R_Low)
8079         and then L_Len = R_Len
8080       then
8081          null;
8082       else
8083          return False;
8084       end if;
8085
8086       --  Then treat all other dimensions
8087
8088       for Indx in 2 .. L_Ndims loop
8089          Next (L_Index);
8090          Next (R_Index);
8091
8092          Get_Index_Bounds (L_Index, L_Low, L_High);
8093          Get_Index_Bounds (R_Index, R_Low, R_High);
8094
8095          if         Is_OK_Static_Expression (L_Low)
8096            and then Is_OK_Static_Expression (L_High)
8097            and then Is_OK_Static_Expression (R_Low)
8098            and then Is_OK_Static_Expression (R_High)
8099            and then Expr_Value (L_Low)  = Expr_Value (R_Low)
8100            and then Expr_Value (L_High) = Expr_Value (R_High)
8101          then
8102             null;
8103          else
8104             return False;
8105          end if;
8106       end loop;
8107
8108       --  If we fall through the loop, all indexes matched
8109
8110       return True;
8111    end Matching_Static_Array_Bounds;
8112
8113    -------------------
8114    -- May_Be_Lvalue --
8115    -------------------
8116
8117    function May_Be_Lvalue (N : Node_Id) return Boolean is
8118       P : constant Node_Id := Parent (N);
8119
8120    begin
8121       case Nkind (P) is
8122
8123          --  Test left side of assignment
8124
8125          when N_Assignment_Statement =>
8126             return N = Name (P);
8127
8128          --  Test prefix of component or attribute. Note that the prefix of an
8129          --  explicit or implicit dereference cannot be an l-value.
8130
8131          when N_Attribute_Reference =>
8132             return N = Prefix (P)
8133               and then Name_Implies_Lvalue_Prefix (Attribute_Name (P));
8134
8135          --  For an expanded name, the name is an lvalue if the expanded name
8136          --  is an lvalue, but the prefix is never an lvalue, since it is just
8137          --  the scope where the name is found.
8138
8139          when N_Expanded_Name        =>
8140             if N = Prefix (P) then
8141                return May_Be_Lvalue (P);
8142             else
8143                return False;
8144             end if;
8145
8146          --  For a selected component A.B, A is certainly an lvalue if A.B is.
8147          --  B is a little interesting, if we have A.B := 3, there is some
8148          --  discussion as to whether B is an lvalue or not, we choose to say
8149          --  it is. Note however that A is not an lvalue if it is of an access
8150          --  type since this is an implicit dereference.
8151
8152          when N_Selected_Component   =>
8153             if N = Prefix (P)
8154               and then Present (Etype (N))
8155               and then Is_Access_Type (Etype (N))
8156             then
8157                return False;
8158             else
8159                return May_Be_Lvalue (P);
8160             end if;
8161
8162          --  For an indexed component or slice, the index or slice bounds is
8163          --  never an lvalue. The prefix is an lvalue if the indexed component
8164          --  or slice is an lvalue, except if it is an access type, where we
8165          --  have an implicit dereference.
8166
8167          when N_Indexed_Component    =>
8168             if N /= Prefix (P)
8169               or else (Present (Etype (N)) and then Is_Access_Type (Etype (N)))
8170             then
8171                return False;
8172             else
8173                return May_Be_Lvalue (P);
8174             end if;
8175
8176          --  Prefix of a reference is an lvalue if the reference is an lvalue
8177
8178          when N_Reference            =>
8179             return May_Be_Lvalue (P);
8180
8181          --  Prefix of explicit dereference is never an lvalue
8182
8183          when N_Explicit_Dereference =>
8184             return False;
8185
8186          --  Positional parameter for subprogram, entry, or accept call.
8187          --  In older versions of Ada function call arguments are never
8188          --  lvalues. In Ada 2012 functions can have in-out parameters.
8189
8190          when N_Function_Call            |
8191               N_Procedure_Call_Statement |
8192               N_Entry_Call_Statement     |
8193               N_Accept_Statement
8194          =>
8195             if Nkind (P) = N_Function_Call
8196               and then Ada_Version < Ada_2012
8197             then
8198                return False;
8199             end if;
8200
8201             --  The following mechanism is clumsy and fragile. A single
8202             --  flag set in Resolve_Actuals would be preferable ???
8203
8204             declare
8205                Proc : Entity_Id;
8206                Form : Entity_Id;
8207                Act  : Node_Id;
8208
8209             begin
8210                Proc := Get_Subprogram_Entity (P);
8211
8212                if No (Proc) then
8213                   return True;
8214                end if;
8215
8216                --  If we are not a list member, something is strange, so
8217                --  be conservative and return True.
8218
8219                if not Is_List_Member (N) then
8220                   return True;
8221                end if;
8222
8223                --  We are going to find the right formal by stepping forward
8224                --  through the formals, as we step backwards in the actuals.
8225
8226                Form := First_Formal (Proc);
8227                Act  := N;
8228                loop
8229                   --  If no formal, something is weird, so be conservative
8230                   --  and return True.
8231
8232                   if No (Form) then
8233                      return True;
8234                   end if;
8235
8236                   Prev (Act);
8237                   exit when No (Act);
8238                   Next_Formal (Form);
8239                end loop;
8240
8241                return Ekind (Form) /= E_In_Parameter;
8242             end;
8243
8244          --  Named parameter for procedure or accept call
8245
8246          when N_Parameter_Association =>
8247             declare
8248                Proc : Entity_Id;
8249                Form : Entity_Id;
8250
8251             begin
8252                Proc := Get_Subprogram_Entity (Parent (P));
8253
8254                if No (Proc) then
8255                   return True;
8256                end if;
8257
8258                --  Loop through formals to find the one that matches
8259
8260                Form := First_Formal (Proc);
8261                loop
8262                   --  If no matching formal, that's peculiar, some kind of
8263                   --  previous error, so return True to be conservative.
8264
8265                   if No (Form) then
8266                      return True;
8267                   end if;
8268
8269                   --  Else test for match
8270
8271                   if Chars (Form) = Chars (Selector_Name (P)) then
8272                      return Ekind (Form) /= E_In_Parameter;
8273                   end if;
8274
8275                   Next_Formal (Form);
8276                end loop;
8277             end;
8278
8279          --  Test for appearing in a conversion that itself appears in an
8280          --  lvalue context, since this should be an lvalue.
8281
8282          when N_Type_Conversion =>
8283             return May_Be_Lvalue (P);
8284
8285          --  Test for appearance in object renaming declaration
8286
8287          when N_Object_Renaming_Declaration =>
8288             return True;
8289
8290          --  All other references are definitely not lvalues
8291
8292          when others =>
8293             return False;
8294
8295       end case;
8296    end May_Be_Lvalue;
8297
8298    -----------------------
8299    -- Mark_Coextensions --
8300    -----------------------
8301
8302    procedure Mark_Coextensions (Context_Nod : Node_Id; Root_Nod : Node_Id) is
8303       Is_Dynamic : Boolean;
8304       --  Indicates whether the context causes nested coextensions to be
8305       --  dynamic or static
8306
8307       function Mark_Allocator (N : Node_Id) return Traverse_Result;
8308       --  Recognize an allocator node and label it as a dynamic coextension
8309
8310       --------------------
8311       -- Mark_Allocator --
8312       --------------------
8313
8314       function Mark_Allocator (N : Node_Id) return Traverse_Result is
8315       begin
8316          if Nkind (N) = N_Allocator then
8317             if Is_Dynamic then
8318                Set_Is_Dynamic_Coextension (N);
8319
8320             --  If the allocator expression is potentially dynamic, it may
8321             --  be expanded out of order and require dynamic allocation
8322             --  anyway, so we treat the coextension itself as dynamic.
8323             --  Potential optimization ???
8324
8325             elsif Nkind (Expression (N)) = N_Qualified_Expression
8326               and then Nkind (Expression (Expression (N))) = N_Op_Concat
8327             then
8328                Set_Is_Dynamic_Coextension (N);
8329
8330             else
8331                Set_Is_Static_Coextension (N);
8332             end if;
8333          end if;
8334
8335          return OK;
8336       end Mark_Allocator;
8337
8338       procedure Mark_Allocators is new Traverse_Proc (Mark_Allocator);
8339
8340    --  Start of processing Mark_Coextensions
8341
8342    begin
8343       case Nkind (Context_Nod) is
8344          when N_Assignment_Statement    |
8345               N_Simple_Return_Statement =>
8346             Is_Dynamic := Nkind (Expression (Context_Nod)) = N_Allocator;
8347
8348          when N_Object_Declaration =>
8349             Is_Dynamic := Nkind (Root_Nod) = N_Allocator;
8350
8351          --  This routine should not be called for constructs which may not
8352          --  contain coextensions.
8353
8354          when others =>
8355             raise Program_Error;
8356       end case;
8357
8358       Mark_Allocators (Root_Nod);
8359    end Mark_Coextensions;
8360
8361    ----------------------
8362    -- Needs_One_Actual --
8363    ----------------------
8364
8365    function Needs_One_Actual (E : Entity_Id) return Boolean is
8366       Formal : Entity_Id;
8367
8368    begin
8369       if Ada_Version >= Ada_2005
8370         and then Present (First_Formal (E))
8371       then
8372          Formal := Next_Formal (First_Formal (E));
8373          while Present (Formal) loop
8374             if No (Default_Value (Formal)) then
8375                return False;
8376             end if;
8377
8378             Next_Formal (Formal);
8379          end loop;
8380
8381          return True;
8382
8383       else
8384          return False;
8385       end if;
8386    end Needs_One_Actual;
8387
8388    ------------------------
8389    -- New_Copy_List_Tree --
8390    ------------------------
8391
8392    function New_Copy_List_Tree (List : List_Id) return List_Id is
8393       NL : List_Id;
8394       E  : Node_Id;
8395
8396    begin
8397       if List = No_List then
8398          return No_List;
8399
8400       else
8401          NL := New_List;
8402          E := First (List);
8403
8404          while Present (E) loop
8405             Append (New_Copy_Tree (E), NL);
8406             E := Next (E);
8407          end loop;
8408
8409          return NL;
8410       end if;
8411    end New_Copy_List_Tree;
8412
8413    -------------------
8414    -- New_Copy_Tree --
8415    -------------------
8416
8417    use Atree.Unchecked_Access;
8418    use Atree_Private_Part;
8419
8420    --  Our approach here requires a two pass traversal of the tree. The
8421    --  first pass visits all nodes that eventually will be copied looking
8422    --  for defining Itypes. If any defining Itypes are found, then they are
8423    --  copied, and an entry is added to the replacement map. In the second
8424    --  phase, the tree is copied, using the replacement map to replace any
8425    --  Itype references within the copied tree.
8426
8427    --  The following hash tables are used if the Map supplied has more
8428    --  than hash threshold entries to speed up access to the map. If
8429    --  there are fewer entries, then the map is searched sequentially
8430    --  (because setting up a hash table for only a few entries takes
8431    --  more time than it saves.
8432
8433    function New_Copy_Hash (E : Entity_Id) return NCT_Header_Num;
8434    --  Hash function used for hash operations
8435
8436    -------------------
8437    -- New_Copy_Hash --
8438    -------------------
8439
8440    function New_Copy_Hash (E : Entity_Id) return NCT_Header_Num is
8441    begin
8442       return Nat (E) mod (NCT_Header_Num'Last + 1);
8443    end New_Copy_Hash;
8444
8445    ---------------
8446    -- NCT_Assoc --
8447    ---------------
8448
8449    --  The hash table NCT_Assoc associates old entities in the table
8450    --  with their corresponding new entities (i.e. the pairs of entries
8451    --  presented in the original Map argument are Key-Element pairs).
8452
8453    package NCT_Assoc is new Simple_HTable (
8454      Header_Num => NCT_Header_Num,
8455      Element    => Entity_Id,
8456      No_Element => Empty,
8457      Key        => Entity_Id,
8458      Hash       => New_Copy_Hash,
8459      Equal      => Types."=");
8460
8461    ---------------------
8462    -- NCT_Itype_Assoc --
8463    ---------------------
8464
8465    --  The hash table NCT_Itype_Assoc contains entries only for those
8466    --  old nodes which have a non-empty Associated_Node_For_Itype set.
8467    --  The key is the associated node, and the element is the new node
8468    --  itself (NOT the associated node for the new node).
8469
8470    package NCT_Itype_Assoc is new Simple_HTable (
8471      Header_Num => NCT_Header_Num,
8472      Element    => Entity_Id,
8473      No_Element => Empty,
8474      Key        => Entity_Id,
8475      Hash       => New_Copy_Hash,
8476      Equal      => Types."=");
8477
8478    --  Start of processing for New_Copy_Tree function
8479
8480    function New_Copy_Tree
8481      (Source    : Node_Id;
8482       Map       : Elist_Id := No_Elist;
8483       New_Sloc  : Source_Ptr := No_Location;
8484       New_Scope : Entity_Id := Empty) return Node_Id
8485    is
8486       Actual_Map : Elist_Id := Map;
8487       --  This is the actual map for the copy. It is initialized with the
8488       --  given elements, and then enlarged as required for Itypes that are
8489       --  copied during the first phase of the copy operation. The visit
8490       --  procedures add elements to this map as Itypes are encountered.
8491       --  The reason we cannot use Map directly, is that it may well be
8492       --  (and normally is) initialized to No_Elist, and if we have mapped
8493       --  entities, we have to reset it to point to a real Elist.
8494
8495       function Assoc (N : Node_Or_Entity_Id) return Node_Id;
8496       --  Called during second phase to map entities into their corresponding
8497       --  copies using Actual_Map. If the argument is not an entity, or is not
8498       --  in Actual_Map, then it is returned unchanged.
8499
8500       procedure Build_NCT_Hash_Tables;
8501       --  Builds hash tables (number of elements >= threshold value)
8502
8503       function Copy_Elist_With_Replacement
8504         (Old_Elist : Elist_Id) return Elist_Id;
8505       --  Called during second phase to copy element list doing replacements
8506
8507       procedure Copy_Itype_With_Replacement (New_Itype : Entity_Id);
8508       --  Called during the second phase to process a copied Itype. The actual
8509       --  copy happened during the first phase (so that we could make the entry
8510       --  in the mapping), but we still have to deal with the descendents of
8511       --  the copied Itype and copy them where necessary.
8512
8513       function Copy_List_With_Replacement (Old_List : List_Id) return List_Id;
8514       --  Called during second phase to copy list doing replacements
8515
8516       function Copy_Node_With_Replacement (Old_Node : Node_Id) return Node_Id;
8517       --  Called during second phase to copy node doing replacements
8518
8519       procedure Visit_Elist (E : Elist_Id);
8520       --  Called during first phase to visit all elements of an Elist
8521
8522       procedure Visit_Field (F : Union_Id; N : Node_Id);
8523       --  Visit a single field, recursing to call Visit_Node or Visit_List
8524       --  if the field is a syntactic descendent of the current node (i.e.
8525       --  its parent is Node N).
8526
8527       procedure Visit_Itype (Old_Itype : Entity_Id);
8528       --  Called during first phase to visit subsidiary fields of a defining
8529       --  Itype, and also create a copy and make an entry in the replacement
8530       --  map for the new copy.
8531
8532       procedure Visit_List (L : List_Id);
8533       --  Called during first phase to visit all elements of a List
8534
8535       procedure Visit_Node (N : Node_Or_Entity_Id);
8536       --  Called during first phase to visit a node and all its subtrees
8537
8538       -----------
8539       -- Assoc --
8540       -----------
8541
8542       function Assoc (N : Node_Or_Entity_Id) return Node_Id is
8543          E   : Elmt_Id;
8544          Ent : Entity_Id;
8545
8546       begin
8547          if not Has_Extension (N) or else No (Actual_Map) then
8548             return N;
8549
8550          elsif NCT_Hash_Tables_Used then
8551             Ent := NCT_Assoc.Get (Entity_Id (N));
8552
8553             if Present (Ent) then
8554                return Ent;
8555             else
8556                return N;
8557             end if;
8558
8559          --  No hash table used, do serial search
8560
8561          else
8562             E := First_Elmt (Actual_Map);
8563             while Present (E) loop
8564                if Node (E) = N then
8565                   return Node (Next_Elmt (E));
8566                else
8567                   E := Next_Elmt (Next_Elmt (E));
8568                end if;
8569             end loop;
8570          end if;
8571
8572          return N;
8573       end Assoc;
8574
8575       ---------------------------
8576       -- Build_NCT_Hash_Tables --
8577       ---------------------------
8578
8579       procedure Build_NCT_Hash_Tables is
8580          Elmt : Elmt_Id;
8581          Ent  : Entity_Id;
8582       begin
8583          if NCT_Hash_Table_Setup then
8584             NCT_Assoc.Reset;
8585             NCT_Itype_Assoc.Reset;
8586          end if;
8587
8588          Elmt := First_Elmt (Actual_Map);
8589          while Present (Elmt) loop
8590             Ent := Node (Elmt);
8591
8592             --  Get new entity, and associate old and new
8593
8594             Next_Elmt (Elmt);
8595             NCT_Assoc.Set (Ent, Node (Elmt));
8596
8597             if Is_Type (Ent) then
8598                declare
8599                   Anode : constant Entity_Id :=
8600                             Associated_Node_For_Itype (Ent);
8601
8602                begin
8603                   if Present (Anode) then
8604
8605                      --  Enter a link between the associated node of the
8606                      --  old Itype and the new Itype, for updating later
8607                      --  when node is copied.
8608
8609                      NCT_Itype_Assoc.Set (Anode, Node (Elmt));
8610                   end if;
8611                end;
8612             end if;
8613
8614             Next_Elmt (Elmt);
8615          end loop;
8616
8617          NCT_Hash_Tables_Used := True;
8618          NCT_Hash_Table_Setup := True;
8619       end Build_NCT_Hash_Tables;
8620
8621       ---------------------------------
8622       -- Copy_Elist_With_Replacement --
8623       ---------------------------------
8624
8625       function Copy_Elist_With_Replacement
8626         (Old_Elist : Elist_Id) return Elist_Id
8627       is
8628          M         : Elmt_Id;
8629          New_Elist : Elist_Id;
8630
8631       begin
8632          if No (Old_Elist) then
8633             return No_Elist;
8634
8635          else
8636             New_Elist := New_Elmt_List;
8637
8638             M := First_Elmt (Old_Elist);
8639             while Present (M) loop
8640                Append_Elmt (Copy_Node_With_Replacement (Node (M)), New_Elist);
8641                Next_Elmt (M);
8642             end loop;
8643          end if;
8644
8645          return New_Elist;
8646       end Copy_Elist_With_Replacement;
8647
8648       ---------------------------------
8649       -- Copy_Itype_With_Replacement --
8650       ---------------------------------
8651
8652       --  This routine exactly parallels its phase one analog Visit_Itype,
8653
8654       procedure Copy_Itype_With_Replacement (New_Itype : Entity_Id) is
8655       begin
8656          --  Translate Next_Entity, Scope and Etype fields, in case they
8657          --  reference entities that have been mapped into copies.
8658
8659          Set_Next_Entity (New_Itype, Assoc (Next_Entity (New_Itype)));
8660          Set_Etype       (New_Itype, Assoc (Etype       (New_Itype)));
8661
8662          if Present (New_Scope) then
8663             Set_Scope    (New_Itype, New_Scope);
8664          else
8665             Set_Scope    (New_Itype, Assoc (Scope       (New_Itype)));
8666          end if;
8667
8668          --  Copy referenced fields
8669
8670          if Is_Discrete_Type (New_Itype) then
8671             Set_Scalar_Range (New_Itype,
8672               Copy_Node_With_Replacement (Scalar_Range (New_Itype)));
8673
8674          elsif Has_Discriminants (Base_Type (New_Itype)) then
8675             Set_Discriminant_Constraint (New_Itype,
8676               Copy_Elist_With_Replacement
8677                 (Discriminant_Constraint (New_Itype)));
8678
8679          elsif Is_Array_Type (New_Itype) then
8680             if Present (First_Index (New_Itype)) then
8681                Set_First_Index (New_Itype,
8682                  First (Copy_List_With_Replacement
8683                          (List_Containing (First_Index (New_Itype)))));
8684             end if;
8685
8686             if Is_Packed (New_Itype) then
8687                Set_Packed_Array_Type (New_Itype,
8688                  Copy_Node_With_Replacement
8689                    (Packed_Array_Type (New_Itype)));
8690             end if;
8691          end if;
8692       end Copy_Itype_With_Replacement;
8693
8694       --------------------------------
8695       -- Copy_List_With_Replacement --
8696       --------------------------------
8697
8698       function Copy_List_With_Replacement
8699         (Old_List : List_Id) return List_Id
8700       is
8701          New_List : List_Id;
8702          E        : Node_Id;
8703
8704       begin
8705          if Old_List = No_List then
8706             return No_List;
8707
8708          else
8709             New_List := Empty_List;
8710
8711             E := First (Old_List);
8712             while Present (E) loop
8713                Append (Copy_Node_With_Replacement (E), New_List);
8714                Next (E);
8715             end loop;
8716
8717             return New_List;
8718          end if;
8719       end Copy_List_With_Replacement;
8720
8721       --------------------------------
8722       -- Copy_Node_With_Replacement --
8723       --------------------------------
8724
8725       function Copy_Node_With_Replacement
8726         (Old_Node : Node_Id) return Node_Id
8727       is
8728          New_Node : Node_Id;
8729
8730          procedure Adjust_Named_Associations
8731            (Old_Node : Node_Id;
8732             New_Node : Node_Id);
8733          --  If a call node has named associations, these are chained through
8734          --  the First_Named_Actual, Next_Named_Actual links. These must be
8735          --  propagated separately to the new parameter list, because these
8736          --  are not syntactic fields.
8737
8738          function Copy_Field_With_Replacement
8739            (Field : Union_Id) return Union_Id;
8740          --  Given Field, which is a field of Old_Node, return a copy of it
8741          --  if it is a syntactic field (i.e. its parent is Node), setting
8742          --  the parent of the copy to poit to New_Node. Otherwise returns
8743          --  the field (possibly mapped if it is an entity).
8744
8745          -------------------------------
8746          -- Adjust_Named_Associations --
8747          -------------------------------
8748
8749          procedure Adjust_Named_Associations
8750            (Old_Node : Node_Id;
8751             New_Node : Node_Id)
8752          is
8753             Old_E : Node_Id;
8754             New_E : Node_Id;
8755
8756             Old_Next : Node_Id;
8757             New_Next : Node_Id;
8758
8759          begin
8760             Old_E := First (Parameter_Associations (Old_Node));
8761             New_E := First (Parameter_Associations (New_Node));
8762             while Present (Old_E) loop
8763                if Nkind (Old_E) = N_Parameter_Association
8764                  and then Present (Next_Named_Actual (Old_E))
8765                then
8766                   if First_Named_Actual (Old_Node)
8767                     =  Explicit_Actual_Parameter (Old_E)
8768                   then
8769                      Set_First_Named_Actual
8770                        (New_Node, Explicit_Actual_Parameter (New_E));
8771                   end if;
8772
8773                   --  Now scan parameter list from the beginning,to locate
8774                   --  next named actual, which can be out of order.
8775
8776                   Old_Next := First (Parameter_Associations (Old_Node));
8777                   New_Next := First (Parameter_Associations (New_Node));
8778
8779                   while Nkind (Old_Next) /= N_Parameter_Association
8780                     or else  Explicit_Actual_Parameter (Old_Next)
8781                       /= Next_Named_Actual (Old_E)
8782                   loop
8783                      Next (Old_Next);
8784                      Next (New_Next);
8785                   end loop;
8786
8787                   Set_Next_Named_Actual
8788                     (New_E, Explicit_Actual_Parameter (New_Next));
8789                end if;
8790
8791                Next (Old_E);
8792                Next (New_E);
8793             end loop;
8794          end Adjust_Named_Associations;
8795
8796          ---------------------------------
8797          -- Copy_Field_With_Replacement --
8798          ---------------------------------
8799
8800          function Copy_Field_With_Replacement
8801            (Field : Union_Id) return Union_Id
8802          is
8803          begin
8804             if Field = Union_Id (Empty) then
8805                return Field;
8806
8807             elsif Field in Node_Range then
8808                declare
8809                   Old_N : constant Node_Id := Node_Id (Field);
8810                   New_N : Node_Id;
8811
8812                begin
8813                   --  If syntactic field, as indicated by the parent pointer
8814                   --  being set, then copy the referenced node recursively.
8815
8816                   if Parent (Old_N) = Old_Node then
8817                      New_N := Copy_Node_With_Replacement (Old_N);
8818
8819                      if New_N /= Old_N then
8820                         Set_Parent (New_N, New_Node);
8821                      end if;
8822
8823                   --  For semantic fields, update possible entity reference
8824                   --  from the replacement map.
8825
8826                   else
8827                      New_N := Assoc (Old_N);
8828                   end if;
8829
8830                   return Union_Id (New_N);
8831                end;
8832
8833             elsif Field in List_Range then
8834                declare
8835                   Old_L : constant List_Id := List_Id (Field);
8836                   New_L : List_Id;
8837
8838                begin
8839                   --  If syntactic field, as indicated by the parent pointer,
8840                   --  then recursively copy the entire referenced list.
8841
8842                   if Parent (Old_L) = Old_Node then
8843                      New_L := Copy_List_With_Replacement (Old_L);
8844                      Set_Parent (New_L, New_Node);
8845
8846                   --  For semantic list, just returned unchanged
8847
8848                   else
8849                      New_L := Old_L;
8850                   end if;
8851
8852                   return Union_Id (New_L);
8853                end;
8854
8855             --  Anything other than a list or a node is returned unchanged
8856
8857             else
8858                return Field;
8859             end if;
8860          end Copy_Field_With_Replacement;
8861
8862       --  Start of processing for Copy_Node_With_Replacement
8863
8864       begin
8865          if Old_Node <= Empty_Or_Error then
8866             return Old_Node;
8867
8868          elsif Has_Extension (Old_Node) then
8869             return Assoc (Old_Node);
8870
8871          else
8872             New_Node := New_Copy (Old_Node);
8873
8874             --  If the node we are copying is the associated node of a
8875             --  previously copied Itype, then adjust the associated node
8876             --  of the copy of that Itype accordingly.
8877
8878             if Present (Actual_Map) then
8879                declare
8880                   E   : Elmt_Id;
8881                   Ent : Entity_Id;
8882
8883                begin
8884                   --  Case of hash table used
8885
8886                   if NCT_Hash_Tables_Used then
8887                      Ent := NCT_Itype_Assoc.Get (Old_Node);
8888
8889                      if Present (Ent) then
8890                         Set_Associated_Node_For_Itype (Ent, New_Node);
8891                      end if;
8892
8893                   --  Case of no hash table used
8894
8895                   else
8896                      E := First_Elmt (Actual_Map);
8897                      while Present (E) loop
8898                         if Is_Itype (Node (E))
8899                           and then
8900                             Old_Node = Associated_Node_For_Itype (Node (E))
8901                         then
8902                            Set_Associated_Node_For_Itype
8903                              (Node (Next_Elmt (E)), New_Node);
8904                         end if;
8905
8906                         E := Next_Elmt (Next_Elmt (E));
8907                      end loop;
8908                   end if;
8909                end;
8910             end if;
8911
8912             --  Recursively copy descendents
8913
8914             Set_Field1
8915               (New_Node, Copy_Field_With_Replacement (Field1 (New_Node)));
8916             Set_Field2
8917               (New_Node, Copy_Field_With_Replacement (Field2 (New_Node)));
8918             Set_Field3
8919               (New_Node, Copy_Field_With_Replacement (Field3 (New_Node)));
8920             Set_Field4
8921               (New_Node, Copy_Field_With_Replacement (Field4 (New_Node)));
8922             Set_Field5
8923               (New_Node, Copy_Field_With_Replacement (Field5 (New_Node)));
8924
8925             --  Adjust Sloc of new node if necessary
8926
8927             if New_Sloc /= No_Location then
8928                Set_Sloc (New_Node, New_Sloc);
8929
8930                --  If we adjust the Sloc, then we are essentially making
8931                --  a completely new node, so the Comes_From_Source flag
8932                --  should be reset to the proper default value.
8933
8934                Nodes.Table (New_Node).Comes_From_Source :=
8935                  Default_Node.Comes_From_Source;
8936             end if;
8937
8938             --  If the node is call and has named associations,
8939             --  set the corresponding links in the copy.
8940
8941             if (Nkind (Old_Node) = N_Function_Call
8942                  or else Nkind (Old_Node) = N_Entry_Call_Statement
8943                  or else
8944                    Nkind (Old_Node) = N_Procedure_Call_Statement)
8945               and then Present (First_Named_Actual (Old_Node))
8946             then
8947                Adjust_Named_Associations (Old_Node, New_Node);
8948             end if;
8949
8950             --  Reset First_Real_Statement for Handled_Sequence_Of_Statements.
8951             --  The replacement mechanism applies to entities, and is not used
8952             --  here. Eventually we may need a more general graph-copying
8953             --  routine. For now, do a sequential search to find desired node.
8954
8955             if Nkind (Old_Node) = N_Handled_Sequence_Of_Statements
8956               and then Present (First_Real_Statement (Old_Node))
8957             then
8958                declare
8959                   Old_F  : constant Node_Id := First_Real_Statement (Old_Node);
8960                   N1, N2 : Node_Id;
8961
8962                begin
8963                   N1 := First (Statements (Old_Node));
8964                   N2 := First (Statements (New_Node));
8965
8966                   while N1 /= Old_F loop
8967                      Next (N1);
8968                      Next (N2);
8969                   end loop;
8970
8971                   Set_First_Real_Statement (New_Node, N2);
8972                end;
8973             end if;
8974          end if;
8975
8976          --  All done, return copied node
8977
8978          return New_Node;
8979       end Copy_Node_With_Replacement;
8980
8981       -----------------
8982       -- Visit_Elist --
8983       -----------------
8984
8985       procedure Visit_Elist (E : Elist_Id) is
8986          Elmt : Elmt_Id;
8987       begin
8988          if Present (E) then
8989             Elmt := First_Elmt (E);
8990
8991             while Elmt /= No_Elmt loop
8992                Visit_Node (Node (Elmt));
8993                Next_Elmt (Elmt);
8994             end loop;
8995          end if;
8996       end Visit_Elist;
8997
8998       -----------------
8999       -- Visit_Field --
9000       -----------------
9001
9002       procedure Visit_Field (F : Union_Id; N : Node_Id) is
9003       begin
9004          if F = Union_Id (Empty) then
9005             return;
9006
9007          elsif F in Node_Range then
9008
9009             --  Copy node if it is syntactic, i.e. its parent pointer is
9010             --  set to point to the field that referenced it (certain
9011             --  Itypes will also meet this criterion, which is fine, since
9012             --  these are clearly Itypes that do need to be copied, since
9013             --  we are copying their parent.)
9014
9015             if Parent (Node_Id (F)) = N then
9016                Visit_Node (Node_Id (F));
9017                return;
9018
9019             --  Another case, if we are pointing to an Itype, then we want
9020             --  to copy it if its associated node is somewhere in the tree
9021             --  being copied.
9022
9023             --  Note: the exclusion of self-referential copies is just an
9024             --  optimization, since the search of the already copied list
9025             --  would catch it, but it is a common case (Etype pointing
9026             --  to itself for an Itype that is a base type).
9027
9028             elsif Has_Extension (Node_Id (F))
9029               and then Is_Itype (Entity_Id (F))
9030               and then Node_Id (F) /= N
9031             then
9032                declare
9033                   P : Node_Id;
9034
9035                begin
9036                   P := Associated_Node_For_Itype (Node_Id (F));
9037                   while Present (P) loop
9038                      if P = Source then
9039                         Visit_Node (Node_Id (F));
9040                         return;
9041                      else
9042                         P := Parent (P);
9043                      end if;
9044                   end loop;
9045
9046                   --  An Itype whose parent is not being copied definitely
9047                   --  should NOT be copied, since it does not belong in any
9048                   --  sense to the copied subtree.
9049
9050                   return;
9051                end;
9052             end if;
9053
9054          elsif F in List_Range
9055            and then Parent (List_Id (F)) = N
9056          then
9057             Visit_List (List_Id (F));
9058             return;
9059          end if;
9060       end Visit_Field;
9061
9062       -----------------
9063       -- Visit_Itype --
9064       -----------------
9065
9066       procedure Visit_Itype (Old_Itype : Entity_Id) is
9067          New_Itype : Entity_Id;
9068          E         : Elmt_Id;
9069          Ent       : Entity_Id;
9070
9071       begin
9072          --  Itypes that describe the designated type of access to subprograms
9073          --  have the structure of subprogram declarations, with signatures,
9074          --  etc. Either we duplicate the signatures completely, or choose to
9075          --  share such itypes, which is fine because their elaboration will
9076          --  have no side effects.
9077
9078          if Ekind (Old_Itype) = E_Subprogram_Type then
9079             return;
9080          end if;
9081
9082          New_Itype := New_Copy (Old_Itype);
9083
9084          --  The new Itype has all the attributes of the old one, and
9085          --  we just copy the contents of the entity. However, the back-end
9086          --  needs different names for debugging purposes, so we create a
9087          --  new internal name for it in all cases.
9088
9089          Set_Chars (New_Itype, New_Internal_Name ('T'));
9090
9091          --  If our associated node is an entity that has already been copied,
9092          --  then set the associated node of the copy to point to the right
9093          --  copy. If we have copied an Itype that is itself the associated
9094          --  node of some previously copied Itype, then we set the right
9095          --  pointer in the other direction.
9096
9097          if Present (Actual_Map) then
9098
9099             --  Case of hash tables used
9100
9101             if NCT_Hash_Tables_Used then
9102
9103                Ent := NCT_Assoc.Get (Associated_Node_For_Itype (Old_Itype));
9104
9105                if Present (Ent) then
9106                   Set_Associated_Node_For_Itype (New_Itype, Ent);
9107                end if;
9108
9109                Ent := NCT_Itype_Assoc.Get (Old_Itype);
9110                if Present (Ent) then
9111                   Set_Associated_Node_For_Itype (Ent, New_Itype);
9112
9113                --  If the hash table has no association for this Itype and
9114                --  its associated node, enter one now.
9115
9116                else
9117                   NCT_Itype_Assoc.Set
9118                     (Associated_Node_For_Itype (Old_Itype), New_Itype);
9119                end if;
9120
9121             --  Case of hash tables not used
9122
9123             else
9124                E := First_Elmt (Actual_Map);
9125                while Present (E) loop
9126                   if Associated_Node_For_Itype (Old_Itype) = Node (E) then
9127                      Set_Associated_Node_For_Itype
9128                        (New_Itype, Node (Next_Elmt (E)));
9129                   end if;
9130
9131                   if Is_Type (Node (E))
9132                     and then
9133                       Old_Itype = Associated_Node_For_Itype (Node (E))
9134                   then
9135                      Set_Associated_Node_For_Itype
9136                        (Node (Next_Elmt (E)), New_Itype);
9137                   end if;
9138
9139                   E := Next_Elmt (Next_Elmt (E));
9140                end loop;
9141             end if;
9142          end if;
9143
9144          if Present (Freeze_Node (New_Itype)) then
9145             Set_Is_Frozen (New_Itype, False);
9146             Set_Freeze_Node (New_Itype, Empty);
9147          end if;
9148
9149          --  Add new association to map
9150
9151          if No (Actual_Map) then
9152             Actual_Map := New_Elmt_List;
9153          end if;
9154
9155          Append_Elmt (Old_Itype, Actual_Map);
9156          Append_Elmt (New_Itype, Actual_Map);
9157
9158          if NCT_Hash_Tables_Used then
9159             NCT_Assoc.Set (Old_Itype, New_Itype);
9160
9161          else
9162             NCT_Table_Entries := NCT_Table_Entries + 1;
9163
9164             if NCT_Table_Entries > NCT_Hash_Threshold then
9165                Build_NCT_Hash_Tables;
9166             end if;
9167          end if;
9168
9169          --  If a record subtype is simply copied, the entity list will be
9170          --  shared. Thus cloned_Subtype must be set to indicate the sharing.
9171
9172          if Ekind_In (Old_Itype, E_Record_Subtype, E_Class_Wide_Subtype) then
9173             Set_Cloned_Subtype (New_Itype, Old_Itype);
9174          end if;
9175
9176          --  Visit descendents that eventually get copied
9177
9178          Visit_Field (Union_Id (Etype (Old_Itype)), Old_Itype);
9179
9180          if Is_Discrete_Type (Old_Itype) then
9181             Visit_Field (Union_Id (Scalar_Range (Old_Itype)), Old_Itype);
9182
9183          elsif Has_Discriminants (Base_Type (Old_Itype)) then
9184             --  ??? This should involve call to Visit_Field
9185             Visit_Elist (Discriminant_Constraint (Old_Itype));
9186
9187          elsif Is_Array_Type (Old_Itype) then
9188             if Present (First_Index (Old_Itype)) then
9189                Visit_Field (Union_Id (List_Containing
9190                                 (First_Index (Old_Itype))),
9191                             Old_Itype);
9192             end if;
9193
9194             if Is_Packed (Old_Itype) then
9195                Visit_Field (Union_Id (Packed_Array_Type (Old_Itype)),
9196                             Old_Itype);
9197             end if;
9198          end if;
9199       end Visit_Itype;
9200
9201       ----------------
9202       -- Visit_List --
9203       ----------------
9204
9205       procedure Visit_List (L : List_Id) is
9206          N : Node_Id;
9207       begin
9208          if L /= No_List then
9209             N := First (L);
9210
9211             while Present (N) loop
9212                Visit_Node (N);
9213                Next (N);
9214             end loop;
9215          end if;
9216       end Visit_List;
9217
9218       ----------------
9219       -- Visit_Node --
9220       ----------------
9221
9222       procedure Visit_Node (N : Node_Or_Entity_Id) is
9223
9224       --  Start of processing for Visit_Node
9225
9226       begin
9227          --  Handle case of an Itype, which must be copied
9228
9229          if Has_Extension (N)
9230            and then Is_Itype (N)
9231          then
9232             --  Nothing to do if already in the list. This can happen with an
9233             --  Itype entity that appears more than once in the tree.
9234             --  Note that we do not want to visit descendents in this case.
9235
9236             --  Test for already in list when hash table is used
9237
9238             if NCT_Hash_Tables_Used then
9239                if Present (NCT_Assoc.Get (Entity_Id (N))) then
9240                   return;
9241                end if;
9242
9243             --  Test for already in list when hash table not used
9244
9245             else
9246                declare
9247                   E : Elmt_Id;
9248                begin
9249                   if Present (Actual_Map) then
9250                      E := First_Elmt (Actual_Map);
9251                      while Present (E) loop
9252                         if Node (E) = N then
9253                            return;
9254                         else
9255                            E := Next_Elmt (Next_Elmt (E));
9256                         end if;
9257                      end loop;
9258                   end if;
9259                end;
9260             end if;
9261
9262             Visit_Itype (N);
9263          end if;
9264
9265          --  Visit descendents
9266
9267          Visit_Field (Field1 (N), N);
9268          Visit_Field (Field2 (N), N);
9269          Visit_Field (Field3 (N), N);
9270          Visit_Field (Field4 (N), N);
9271          Visit_Field (Field5 (N), N);
9272       end Visit_Node;
9273
9274    --  Start of processing for New_Copy_Tree
9275
9276    begin
9277       Actual_Map := Map;
9278
9279       --  See if we should use hash table
9280
9281       if No (Actual_Map) then
9282          NCT_Hash_Tables_Used := False;
9283
9284       else
9285          declare
9286             Elmt : Elmt_Id;
9287
9288          begin
9289             NCT_Table_Entries := 0;
9290
9291             Elmt := First_Elmt (Actual_Map);
9292             while Present (Elmt) loop
9293                NCT_Table_Entries := NCT_Table_Entries + 1;
9294                Next_Elmt (Elmt);
9295                Next_Elmt (Elmt);
9296             end loop;
9297
9298             if NCT_Table_Entries > NCT_Hash_Threshold then
9299                Build_NCT_Hash_Tables;
9300             else
9301                NCT_Hash_Tables_Used := False;
9302             end if;
9303          end;
9304       end if;
9305
9306       --  Hash table set up if required, now start phase one by visiting
9307       --  top node (we will recursively visit the descendents).
9308
9309       Visit_Node (Source);
9310
9311       --  Now the second phase of the copy can start. First we process
9312       --  all the mapped entities, copying their descendents.
9313
9314       if Present (Actual_Map) then
9315          declare
9316             Elmt      : Elmt_Id;
9317             New_Itype : Entity_Id;
9318          begin
9319             Elmt := First_Elmt (Actual_Map);
9320             while Present (Elmt) loop
9321                Next_Elmt (Elmt);
9322                New_Itype := Node (Elmt);
9323                Copy_Itype_With_Replacement (New_Itype);
9324                Next_Elmt (Elmt);
9325             end loop;
9326          end;
9327       end if;
9328
9329       --  Now we can copy the actual tree
9330
9331       return Copy_Node_With_Replacement (Source);
9332    end New_Copy_Tree;
9333
9334    -------------------------
9335    -- New_External_Entity --
9336    -------------------------
9337
9338    function New_External_Entity
9339      (Kind         : Entity_Kind;
9340       Scope_Id     : Entity_Id;
9341       Sloc_Value   : Source_Ptr;
9342       Related_Id   : Entity_Id;
9343       Suffix       : Character;
9344       Suffix_Index : Nat := 0;
9345       Prefix       : Character := ' ') return Entity_Id
9346    is
9347       N : constant Entity_Id :=
9348             Make_Defining_Identifier (Sloc_Value,
9349               New_External_Name
9350                 (Chars (Related_Id), Suffix, Suffix_Index, Prefix));
9351
9352    begin
9353       Set_Ekind          (N, Kind);
9354       Set_Is_Internal    (N, True);
9355       Append_Entity      (N, Scope_Id);
9356       Set_Public_Status  (N);
9357
9358       if Kind in Type_Kind then
9359          Init_Size_Align (N);
9360       end if;
9361
9362       return N;
9363    end New_External_Entity;
9364
9365    -------------------------
9366    -- New_Internal_Entity --
9367    -------------------------
9368
9369    function New_Internal_Entity
9370      (Kind       : Entity_Kind;
9371       Scope_Id   : Entity_Id;
9372       Sloc_Value : Source_Ptr;
9373       Id_Char    : Character) return Entity_Id
9374    is
9375       N : constant Entity_Id := Make_Temporary (Sloc_Value, Id_Char);
9376
9377    begin
9378       Set_Ekind          (N, Kind);
9379       Set_Is_Internal    (N, True);
9380       Append_Entity      (N, Scope_Id);
9381
9382       if Kind in Type_Kind then
9383          Init_Size_Align (N);
9384       end if;
9385
9386       return N;
9387    end New_Internal_Entity;
9388
9389    -----------------
9390    -- Next_Actual --
9391    -----------------
9392
9393    function Next_Actual (Actual_Id : Node_Id) return Node_Id is
9394       N  : Node_Id;
9395
9396    begin
9397       --  If we are pointing at a positional parameter, it is a member of a
9398       --  node list (the list of parameters), and the next parameter is the
9399       --  next node on the list, unless we hit a parameter association, then
9400       --  we shift to using the chain whose head is the First_Named_Actual in
9401       --  the parent, and then is threaded using the Next_Named_Actual of the
9402       --  Parameter_Association. All this fiddling is because the original node
9403       --  list is in the textual call order, and what we need is the
9404       --  declaration order.
9405
9406       if Is_List_Member (Actual_Id) then
9407          N := Next (Actual_Id);
9408
9409          if Nkind (N) = N_Parameter_Association then
9410             return First_Named_Actual (Parent (Actual_Id));
9411          else
9412             return N;
9413          end if;
9414
9415       else
9416          return Next_Named_Actual (Parent (Actual_Id));
9417       end if;
9418    end Next_Actual;
9419
9420    procedure Next_Actual (Actual_Id : in out Node_Id) is
9421    begin
9422       Actual_Id := Next_Actual (Actual_Id);
9423    end Next_Actual;
9424
9425    -----------------------
9426    -- Normalize_Actuals --
9427    -----------------------
9428
9429    --  Chain actuals according to formals of subprogram. If there are no named
9430    --  associations, the chain is simply the list of Parameter Associations,
9431    --  since the order is the same as the declaration order. If there are named
9432    --  associations, then the First_Named_Actual field in the N_Function_Call
9433    --  or N_Procedure_Call_Statement node points to the Parameter_Association
9434    --  node for the parameter that comes first in declaration order. The
9435    --  remaining named parameters are then chained in declaration order using
9436    --  Next_Named_Actual.
9437
9438    --  This routine also verifies that the number of actuals is compatible with
9439    --  the number and default values of formals, but performs no type checking
9440    --  (type checking is done by the caller).
9441
9442    --  If the matching succeeds, Success is set to True and the caller proceeds
9443    --  with type-checking. If the match is unsuccessful, then Success is set to
9444    --  False, and the caller attempts a different interpretation, if there is
9445    --  one.
9446
9447    --  If the flag Report is on, the call is not overloaded, and a failure to
9448    --  match can be reported here, rather than in the caller.
9449
9450    procedure Normalize_Actuals
9451      (N       : Node_Id;
9452       S       : Entity_Id;
9453       Report  : Boolean;
9454       Success : out Boolean)
9455    is
9456       Actuals     : constant List_Id := Parameter_Associations (N);
9457       Actual      : Node_Id := Empty;
9458       Formal      : Entity_Id;
9459       Last        : Node_Id := Empty;
9460       First_Named : Node_Id := Empty;
9461       Found       : Boolean;
9462
9463       Formals_To_Match : Integer := 0;
9464       Actuals_To_Match : Integer := 0;
9465
9466       procedure Chain (A : Node_Id);
9467       --  Add named actual at the proper place in the list, using the
9468       --  Next_Named_Actual link.
9469
9470       function Reporting return Boolean;
9471       --  Determines if an error is to be reported. To report an error, we
9472       --  need Report to be True, and also we do not report errors caused
9473       --  by calls to init procs that occur within other init procs. Such
9474       --  errors must always be cascaded errors, since if all the types are
9475       --  declared correctly, the compiler will certainly build decent calls!
9476
9477       -----------
9478       -- Chain --
9479       -----------
9480
9481       procedure Chain (A : Node_Id) is
9482       begin
9483          if No (Last) then
9484
9485             --  Call node points to first actual in list
9486
9487             Set_First_Named_Actual (N, Explicit_Actual_Parameter (A));
9488
9489          else
9490             Set_Next_Named_Actual (Last, Explicit_Actual_Parameter (A));
9491          end if;
9492
9493          Last := A;
9494          Set_Next_Named_Actual (Last, Empty);
9495       end Chain;
9496
9497       ---------------
9498       -- Reporting --
9499       ---------------
9500
9501       function Reporting return Boolean is
9502       begin
9503          if not Report then
9504             return False;
9505
9506          elsif not Within_Init_Proc then
9507             return True;
9508
9509          elsif Is_Init_Proc (Entity (Name (N))) then
9510             return False;
9511
9512          else
9513             return True;
9514          end if;
9515       end Reporting;
9516
9517    --  Start of processing for Normalize_Actuals
9518
9519    begin
9520       if Is_Access_Type (S) then
9521
9522          --  The name in the call is a function call that returns an access
9523          --  to subprogram. The designated type has the list of formals.
9524
9525          Formal := First_Formal (Designated_Type (S));
9526       else
9527          Formal := First_Formal (S);
9528       end if;
9529
9530       while Present (Formal) loop
9531          Formals_To_Match := Formals_To_Match + 1;
9532          Next_Formal (Formal);
9533       end loop;
9534
9535       --  Find if there is a named association, and verify that no positional
9536       --  associations appear after named ones.
9537
9538       if Present (Actuals) then
9539          Actual := First (Actuals);
9540       end if;
9541
9542       while Present (Actual)
9543         and then Nkind (Actual) /= N_Parameter_Association
9544       loop
9545          Actuals_To_Match := Actuals_To_Match + 1;
9546          Next (Actual);
9547       end loop;
9548
9549       if No (Actual) and Actuals_To_Match = Formals_To_Match then
9550
9551          --  Most common case: positional notation, no defaults
9552
9553          Success := True;
9554          return;
9555
9556       elsif Actuals_To_Match > Formals_To_Match then
9557
9558          --  Too many actuals: will not work
9559
9560          if Reporting then
9561             if Is_Entity_Name (Name (N)) then
9562                Error_Msg_N ("too many arguments in call to&", Name (N));
9563             else
9564                Error_Msg_N ("too many arguments in call", N);
9565             end if;
9566          end if;
9567
9568          Success := False;
9569          return;
9570       end if;
9571
9572       First_Named := Actual;
9573
9574       while Present (Actual) loop
9575          if Nkind (Actual) /= N_Parameter_Association then
9576             Error_Msg_N
9577               ("positional parameters not allowed after named ones", Actual);
9578             Success := False;
9579             return;
9580
9581          else
9582             Actuals_To_Match := Actuals_To_Match + 1;
9583          end if;
9584
9585          Next (Actual);
9586       end loop;
9587
9588       if Present (Actuals) then
9589          Actual := First (Actuals);
9590       end if;
9591
9592       Formal := First_Formal (S);
9593       while Present (Formal) loop
9594
9595          --  Match the formals in order. If the corresponding actual is
9596          --  positional, nothing to do. Else scan the list of named actuals
9597          --  to find the one with the right name.
9598
9599          if Present (Actual)
9600            and then Nkind (Actual) /= N_Parameter_Association
9601          then
9602             Next (Actual);
9603             Actuals_To_Match := Actuals_To_Match - 1;
9604             Formals_To_Match := Formals_To_Match - 1;
9605
9606          else
9607             --  For named parameters, search the list of actuals to find
9608             --  one that matches the next formal name.
9609
9610             Actual := First_Named;
9611             Found  := False;
9612             while Present (Actual) loop
9613                if Chars (Selector_Name (Actual)) = Chars (Formal) then
9614                   Found := True;
9615                   Chain (Actual);
9616                   Actuals_To_Match := Actuals_To_Match - 1;
9617                   Formals_To_Match := Formals_To_Match - 1;
9618                   exit;
9619                end if;
9620
9621                Next (Actual);
9622             end loop;
9623
9624             if not Found then
9625                if Ekind (Formal) /= E_In_Parameter
9626                  or else No (Default_Value (Formal))
9627                then
9628                   if Reporting then
9629                      if (Comes_From_Source (S)
9630                           or else Sloc (S) = Standard_Location)
9631                        and then Is_Overloadable (S)
9632                      then
9633                         if No (Actuals)
9634                           and then
9635                            (Nkind (Parent (N)) = N_Procedure_Call_Statement
9636                              or else
9637                            (Nkind (Parent (N)) = N_Function_Call
9638                              or else
9639                             Nkind (Parent (N)) = N_Parameter_Association))
9640                           and then Ekind (S) /= E_Function
9641                         then
9642                            Set_Etype (N, Etype (S));
9643                         else
9644                            Error_Msg_Name_1 := Chars (S);
9645                            Error_Msg_Sloc := Sloc (S);
9646                            Error_Msg_NE
9647                              ("missing argument for parameter & " &
9648                                 "in call to % declared #", N, Formal);
9649                         end if;
9650
9651                      elsif Is_Overloadable (S) then
9652                         Error_Msg_Name_1 := Chars (S);
9653
9654                         --  Point to type derivation that generated the
9655                         --  operation.
9656
9657                         Error_Msg_Sloc := Sloc (Parent (S));
9658
9659                         Error_Msg_NE
9660                           ("missing argument for parameter & " &
9661                              "in call to % (inherited) #", N, Formal);
9662
9663                      else
9664                         Error_Msg_NE
9665                           ("missing argument for parameter &", N, Formal);
9666                      end if;
9667                   end if;
9668
9669                   Success := False;
9670                   return;
9671
9672                else
9673                   Formals_To_Match := Formals_To_Match - 1;
9674                end if;
9675             end if;
9676          end if;
9677
9678          Next_Formal (Formal);
9679       end loop;
9680
9681       if Formals_To_Match = 0 and then Actuals_To_Match = 0 then
9682          Success := True;
9683          return;
9684
9685       else
9686          if Reporting then
9687
9688             --  Find some superfluous named actual that did not get
9689             --  attached to the list of associations.
9690
9691             Actual := First (Actuals);
9692             while Present (Actual) loop
9693                if Nkind (Actual) = N_Parameter_Association
9694                  and then Actual /= Last
9695                  and then No (Next_Named_Actual (Actual))
9696                then
9697                   Error_Msg_N ("unmatched actual & in call",
9698                     Selector_Name (Actual));
9699                   exit;
9700                end if;
9701
9702                Next (Actual);
9703             end loop;
9704          end if;
9705
9706          Success := False;
9707          return;
9708       end if;
9709    end Normalize_Actuals;
9710
9711    --------------------------------
9712    -- Note_Possible_Modification --
9713    --------------------------------
9714
9715    procedure Note_Possible_Modification (N : Node_Id; Sure : Boolean) is
9716       Modification_Comes_From_Source : constant Boolean :=
9717                                          Comes_From_Source (Parent (N));
9718
9719       Ent : Entity_Id;
9720       Exp : Node_Id;
9721
9722    begin
9723       --  Loop to find referenced entity, if there is one
9724
9725       Exp := N;
9726       loop
9727          <<Continue>>
9728          Ent := Empty;
9729
9730          if Is_Entity_Name (Exp) then
9731             Ent := Entity (Exp);
9732
9733             --  If the entity is missing, it is an undeclared identifier,
9734             --  and there is nothing to annotate.
9735
9736             if No (Ent) then
9737                return;
9738             end if;
9739
9740          elsif Nkind (Exp) = N_Explicit_Dereference then
9741             declare
9742                P : constant Node_Id := Prefix (Exp);
9743
9744             begin
9745                if Nkind (P) = N_Selected_Component
9746                  and then Present (
9747                    Entry_Formal (Entity (Selector_Name (P))))
9748                then
9749                   --  Case of a reference to an entry formal
9750
9751                   Ent := Entry_Formal (Entity (Selector_Name (P)));
9752
9753                elsif Nkind (P) = N_Identifier
9754                  and then Nkind (Parent (Entity (P))) = N_Object_Declaration
9755                  and then Present (Expression (Parent (Entity (P))))
9756                  and then Nkind (Expression (Parent (Entity (P))))
9757                    = N_Reference
9758                then
9759                   --  Case of a reference to a value on which side effects have
9760                   --  been removed.
9761
9762                   Exp := Prefix (Expression (Parent (Entity (P))));
9763                   goto Continue;
9764
9765                else
9766                   return;
9767
9768                end if;
9769             end;
9770
9771          elsif     Nkind (Exp) = N_Type_Conversion
9772            or else Nkind (Exp) = N_Unchecked_Type_Conversion
9773          then
9774             Exp := Expression (Exp);
9775             goto Continue;
9776
9777          elsif     Nkind (Exp) = N_Slice
9778            or else Nkind (Exp) = N_Indexed_Component
9779            or else Nkind (Exp) = N_Selected_Component
9780          then
9781             Exp := Prefix (Exp);
9782             goto Continue;
9783
9784          else
9785             return;
9786          end if;
9787
9788          --  Now look for entity being referenced
9789
9790          if Present (Ent) then
9791             if Is_Object (Ent) then
9792                if Comes_From_Source (Exp)
9793                  or else Modification_Comes_From_Source
9794                then
9795                   --  Give warning if pragma unmodified given and we are
9796                   --  sure this is a modification.
9797
9798                   if Has_Pragma_Unmodified (Ent) and then Sure then
9799                      Error_Msg_NE ("?pragma Unmodified given for &!", N, Ent);
9800                   end if;
9801
9802                   Set_Never_Set_In_Source (Ent, False);
9803                end if;
9804
9805                Set_Is_True_Constant (Ent, False);
9806                Set_Current_Value    (Ent, Empty);
9807                Set_Is_Known_Null    (Ent, False);
9808
9809                if not Can_Never_Be_Null (Ent) then
9810                   Set_Is_Known_Non_Null (Ent, False);
9811                end if;
9812
9813                --  Follow renaming chain
9814
9815                if (Ekind (Ent) = E_Variable or else Ekind (Ent) = E_Constant)
9816                  and then Present (Renamed_Object (Ent))
9817                then
9818                   Exp := Renamed_Object (Ent);
9819                   goto Continue;
9820                end if;
9821
9822                --  Generate a reference only if the assignment comes from
9823                --  source. This excludes, for example, calls to a dispatching
9824                --  assignment operation when the left-hand side is tagged.
9825
9826                if Modification_Comes_From_Source then
9827                   Generate_Reference (Ent, Exp, 'm');
9828
9829                   --  If the target of the assignment is the bound variable
9830                   --  in an iterator, indicate that the corresponding array
9831                   --  or container is also modified.
9832
9833                   if Ada_Version >= Ada_2012
9834                     and then
9835                       Nkind (Parent (Ent)) = N_Iterator_Specification
9836                   then
9837                      declare
9838                         Domain : constant Node_Id := Name (Parent (Ent));
9839
9840                      begin
9841                         --  TBD : in the full version of the construct, the
9842                         --  domain of iteration can be given by an expression.
9843
9844                         if Is_Entity_Name (Domain) then
9845                            Generate_Reference      (Entity (Domain), Exp, 'm');
9846                            Set_Is_True_Constant    (Entity (Domain), False);
9847                            Set_Never_Set_In_Source (Entity (Domain), False);
9848                         end if;
9849                      end;
9850                   end if;
9851                end if;
9852
9853                Check_Nested_Access (Ent);
9854             end if;
9855
9856             Kill_Checks (Ent);
9857
9858             --  If we are sure this is a modification from source, and we know
9859             --  this modifies a constant, then give an appropriate warning.
9860
9861             if Overlays_Constant (Ent)
9862               and then Modification_Comes_From_Source
9863               and then Sure
9864             then
9865                declare
9866                   A : constant Node_Id := Address_Clause (Ent);
9867                begin
9868                   if Present (A) then
9869                      declare
9870                         Exp : constant Node_Id := Expression (A);
9871                      begin
9872                         if Nkind (Exp) = N_Attribute_Reference
9873                           and then Attribute_Name (Exp) = Name_Address
9874                           and then Is_Entity_Name (Prefix (Exp))
9875                         then
9876                            Error_Msg_Sloc := Sloc (A);
9877                            Error_Msg_NE
9878                              ("constant& may be modified via address clause#?",
9879                               N, Entity (Prefix (Exp)));
9880                         end if;
9881                      end;
9882                   end if;
9883                end;
9884             end if;
9885
9886             return;
9887          end if;
9888       end loop;
9889    end Note_Possible_Modification;
9890
9891    -------------------------
9892    -- Object_Access_Level --
9893    -------------------------
9894
9895    function Object_Access_Level (Obj : Node_Id) return Uint is
9896       E : Entity_Id;
9897
9898    --  Returns the static accessibility level of the view denoted by Obj. Note
9899    --  that the value returned is the result of a call to Scope_Depth. Only
9900    --  scope depths associated with dynamic scopes can actually be returned.
9901    --  Since only relative levels matter for accessibility checking, the fact
9902    --  that the distance between successive levels of accessibility is not
9903    --  always one is immaterial (invariant: if level(E2) is deeper than
9904    --  level(E1), then Scope_Depth(E1) < Scope_Depth(E2)).
9905
9906       function Reference_To (Obj : Node_Id) return Node_Id;
9907       --  An explicit dereference is created when removing side-effects from
9908       --  expressions for constraint checking purposes. In this case a local
9909       --  access type is created for it. The correct access level is that of
9910       --  the original source node. We detect this case by noting that the
9911       --  prefix of the dereference is created by an object declaration whose
9912       --  initial expression is a reference.
9913
9914       ------------------
9915       -- Reference_To --
9916       ------------------
9917
9918       function Reference_To (Obj : Node_Id) return Node_Id is
9919          Pref : constant Node_Id := Prefix (Obj);
9920       begin
9921          if Is_Entity_Name (Pref)
9922            and then Nkind (Parent (Entity (Pref))) = N_Object_Declaration
9923            and then Present (Expression (Parent (Entity (Pref))))
9924            and then Nkind (Expression (Parent (Entity (Pref)))) = N_Reference
9925          then
9926             return (Prefix (Expression (Parent (Entity (Pref)))));
9927          else
9928             return Empty;
9929          end if;
9930       end Reference_To;
9931
9932    --  Start of processing for Object_Access_Level
9933
9934    begin
9935       if Is_Entity_Name (Obj) then
9936          E := Entity (Obj);
9937
9938          if Is_Prival (E) then
9939             E := Prival_Link (E);
9940          end if;
9941
9942          --  If E is a type then it denotes a current instance. For this case
9943          --  we add one to the normal accessibility level of the type to ensure
9944          --  that current instances are treated as always being deeper than
9945          --  than the level of any visible named access type (see 3.10.2(21)).
9946
9947          if Is_Type (E) then
9948             return Type_Access_Level (E) +  1;
9949
9950          elsif Present (Renamed_Object (E)) then
9951             return Object_Access_Level (Renamed_Object (E));
9952
9953          --  Similarly, if E is a component of the current instance of a
9954          --  protected type, any instance of it is assumed to be at a deeper
9955          --  level than the type. For a protected object (whose type is an
9956          --  anonymous protected type) its components are at the same level
9957          --  as the type itself.
9958
9959          elsif not Is_Overloadable (E)
9960            and then Ekind (Scope (E)) = E_Protected_Type
9961            and then Comes_From_Source (Scope (E))
9962          then
9963             return Type_Access_Level (Scope (E)) + 1;
9964
9965          else
9966             return Scope_Depth (Enclosing_Dynamic_Scope (E));
9967          end if;
9968
9969       elsif Nkind (Obj) = N_Selected_Component then
9970          if Is_Access_Type (Etype (Prefix (Obj))) then
9971             return Type_Access_Level (Etype (Prefix (Obj)));
9972          else
9973             return Object_Access_Level (Prefix (Obj));
9974          end if;
9975
9976       elsif Nkind (Obj) = N_Indexed_Component then
9977          if Is_Access_Type (Etype (Prefix (Obj))) then
9978             return Type_Access_Level (Etype (Prefix (Obj)));
9979          else
9980             return Object_Access_Level (Prefix (Obj));
9981          end if;
9982
9983       elsif Nkind (Obj) = N_Explicit_Dereference then
9984
9985          --  If the prefix is a selected access discriminant then we make a
9986          --  recursive call on the prefix, which will in turn check the level
9987          --  of the prefix object of the selected discriminant.
9988
9989          if Nkind (Prefix (Obj)) = N_Selected_Component
9990            and then Ekind (Etype (Prefix (Obj))) = E_Anonymous_Access_Type
9991            and then
9992              Ekind (Entity (Selector_Name (Prefix (Obj)))) = E_Discriminant
9993          then
9994             return Object_Access_Level (Prefix (Obj));
9995
9996          elsif not (Comes_From_Source (Obj)) then
9997             declare
9998                Ref : constant Node_Id := Reference_To (Obj);
9999             begin
10000                if Present (Ref) then
10001                   return Object_Access_Level (Ref);
10002                else
10003                   return Type_Access_Level (Etype (Prefix (Obj)));
10004                end if;
10005             end;
10006
10007          else
10008             return Type_Access_Level (Etype (Prefix (Obj)));
10009          end if;
10010
10011       elsif Nkind (Obj) = N_Type_Conversion
10012         or else Nkind (Obj) = N_Unchecked_Type_Conversion
10013       then
10014          return Object_Access_Level (Expression (Obj));
10015
10016       elsif Nkind (Obj) = N_Function_Call then
10017
10018          --  Function results are objects, so we get either the access level of
10019          --  the function or, in the case of an indirect call, the level of the
10020          --  access-to-subprogram type. (This code is used for Ada 95, but it
10021          --  looks wrong, because it seems that we should be checking the level
10022          --  of the call itself, even for Ada 95. However, using the Ada 2005
10023          --  version of the code causes regressions in several tests that are
10024          --  compiled with -gnat95. ???)
10025
10026          if Ada_Version < Ada_2005 then
10027             if Is_Entity_Name (Name (Obj)) then
10028                return Subprogram_Access_Level (Entity (Name (Obj)));
10029             else
10030                return Type_Access_Level (Etype (Prefix (Name (Obj))));
10031             end if;
10032
10033          --  For Ada 2005, the level of the result object of a function call is
10034          --  defined to be the level of the call's innermost enclosing master.
10035          --  We determine that by querying the depth of the innermost enclosing
10036          --  dynamic scope.
10037
10038          else
10039             Return_Master_Scope_Depth_Of_Call : declare
10040
10041                function Innermost_Master_Scope_Depth
10042                  (N : Node_Id) return Uint;
10043                --  Returns the scope depth of the given node's innermost
10044                --  enclosing dynamic scope (effectively the accessibility
10045                --  level of the innermost enclosing master).
10046
10047                ----------------------------------
10048                -- Innermost_Master_Scope_Depth --
10049                ----------------------------------
10050
10051                function Innermost_Master_Scope_Depth
10052                  (N : Node_Id) return Uint
10053                is
10054                   Node_Par : Node_Id := Parent (N);
10055
10056                begin
10057                   --  Locate the nearest enclosing node (by traversing Parents)
10058                   --  that Defining_Entity can be applied to, and return the
10059                   --  depth of that entity's nearest enclosing dynamic scope.
10060
10061                   while Present (Node_Par) loop
10062                      case Nkind (Node_Par) is
10063                         when N_Component_Declaration           |
10064                              N_Entry_Declaration               |
10065                              N_Formal_Object_Declaration       |
10066                              N_Formal_Type_Declaration         |
10067                              N_Full_Type_Declaration           |
10068                              N_Incomplete_Type_Declaration     |
10069                              N_Loop_Parameter_Specification    |
10070                              N_Object_Declaration              |
10071                              N_Protected_Type_Declaration      |
10072                              N_Private_Extension_Declaration   |
10073                              N_Private_Type_Declaration        |
10074                              N_Subtype_Declaration             |
10075                              N_Function_Specification          |
10076                              N_Procedure_Specification         |
10077                              N_Task_Type_Declaration           |
10078                              N_Body_Stub                       |
10079                              N_Generic_Instantiation           |
10080                              N_Proper_Body                     |
10081                              N_Implicit_Label_Declaration      |
10082                              N_Package_Declaration             |
10083                              N_Single_Task_Declaration         |
10084                              N_Subprogram_Declaration          |
10085                              N_Generic_Declaration             |
10086                              N_Renaming_Declaration            |
10087                              N_Block_Statement                 |
10088                              N_Formal_Subprogram_Declaration   |
10089                              N_Abstract_Subprogram_Declaration |
10090                              N_Entry_Body                      |
10091                              N_Exception_Declaration           |
10092                              N_Formal_Package_Declaration      |
10093                              N_Number_Declaration              |
10094                              N_Package_Specification           |
10095                              N_Parameter_Specification         |
10096                              N_Single_Protected_Declaration    |
10097                              N_Subunit                         =>
10098
10099                            return Scope_Depth
10100                                     (Nearest_Dynamic_Scope
10101                                        (Defining_Entity (Node_Par)));
10102
10103                         when others =>
10104                            null;
10105                      end case;
10106
10107                      Node_Par := Parent (Node_Par);
10108                   end loop;
10109
10110                   pragma Assert (False);
10111
10112                   --  Should never reach the following return
10113
10114                   return Scope_Depth (Current_Scope) + 1;
10115                end Innermost_Master_Scope_Depth;
10116
10117             --  Start of processing for Return_Master_Scope_Depth_Of_Call
10118
10119             begin
10120                return Innermost_Master_Scope_Depth (Obj);
10121             end Return_Master_Scope_Depth_Of_Call;
10122          end if;
10123
10124       --  For convenience we handle qualified expressions, even though
10125       --  they aren't technically object names.
10126
10127       elsif Nkind (Obj) = N_Qualified_Expression then
10128          return Object_Access_Level (Expression (Obj));
10129
10130       --  Otherwise return the scope level of Standard.
10131       --  (If there are cases that fall through
10132       --  to this point they will be treated as
10133       --  having global accessibility for now. ???)
10134
10135       else
10136          return Scope_Depth (Standard_Standard);
10137       end if;
10138    end Object_Access_Level;
10139
10140    --------------------------------------
10141    -- Original_Corresponding_Operation --
10142    --------------------------------------
10143
10144    function Original_Corresponding_Operation (S : Entity_Id) return Entity_Id
10145    is
10146       Typ : constant Entity_Id := Find_Dispatching_Type (S);
10147
10148    begin
10149       --  If S is an inherited primitive S2 the original corresponding
10150       --  operation of S is the original corresponding operation of S2
10151
10152       if Present (Alias (S))
10153         and then Find_Dispatching_Type (Alias (S)) /= Typ
10154       then
10155          return Original_Corresponding_Operation (Alias (S));
10156
10157       --  If S overrides an inherited subprogram S2 the original corresponding
10158       --  operation of S is the original corresponding operation of S2
10159
10160       elsif Present (Overridden_Operation (S)) then
10161          return Original_Corresponding_Operation (Overridden_Operation (S));
10162
10163       --  otherwise it is S itself
10164
10165       else
10166          return S;
10167       end if;
10168    end Original_Corresponding_Operation;
10169
10170    -----------------------
10171    -- Private_Component --
10172    -----------------------
10173
10174    function Private_Component (Type_Id : Entity_Id) return Entity_Id is
10175       Ancestor  : constant Entity_Id := Base_Type (Type_Id);
10176
10177       function Trace_Components
10178         (T     : Entity_Id;
10179          Check : Boolean) return Entity_Id;
10180       --  Recursive function that does the work, and checks against circular
10181       --  definition for each subcomponent type.
10182
10183       ----------------------
10184       -- Trace_Components --
10185       ----------------------
10186
10187       function Trace_Components
10188          (T     : Entity_Id;
10189           Check : Boolean) return Entity_Id
10190        is
10191          Btype     : constant Entity_Id := Base_Type (T);
10192          Component : Entity_Id;
10193          P         : Entity_Id;
10194          Candidate : Entity_Id := Empty;
10195
10196       begin
10197          if Check and then Btype = Ancestor then
10198             Error_Msg_N ("circular type definition", Type_Id);
10199             return Any_Type;
10200          end if;
10201
10202          if Is_Private_Type (Btype)
10203            and then not Is_Generic_Type (Btype)
10204          then
10205             if Present (Full_View (Btype))
10206               and then Is_Record_Type (Full_View (Btype))
10207               and then not Is_Frozen (Btype)
10208             then
10209                --  To indicate that the ancestor depends on a private type, the
10210                --  current Btype is sufficient. However, to check for circular
10211                --  definition we must recurse on the full view.
10212
10213                Candidate := Trace_Components (Full_View (Btype), True);
10214
10215                if Candidate = Any_Type then
10216                   return Any_Type;
10217                else
10218                   return Btype;
10219                end if;
10220
10221             else
10222                return Btype;
10223             end if;
10224
10225          elsif Is_Array_Type (Btype) then
10226             return Trace_Components (Component_Type (Btype), True);
10227
10228          elsif Is_Record_Type (Btype) then
10229             Component := First_Entity (Btype);
10230             while Present (Component) loop
10231
10232                --  Skip anonymous types generated by constrained components
10233
10234                if not Is_Type (Component) then
10235                   P := Trace_Components (Etype (Component), True);
10236
10237                   if Present (P) then
10238                      if P = Any_Type then
10239                         return P;
10240                      else
10241                         Candidate := P;
10242                      end if;
10243                   end if;
10244                end if;
10245
10246                Next_Entity (Component);
10247             end loop;
10248
10249             return Candidate;
10250
10251          else
10252             return Empty;
10253          end if;
10254       end Trace_Components;
10255
10256    --  Start of processing for Private_Component
10257
10258    begin
10259       return Trace_Components (Type_Id, False);
10260    end Private_Component;
10261
10262    ---------------------------
10263    -- Primitive_Names_Match --
10264    ---------------------------
10265
10266    function Primitive_Names_Match (E1, E2 : Entity_Id) return Boolean is
10267
10268       function Non_Internal_Name (E : Entity_Id) return Name_Id;
10269       --  Given an internal name, returns the corresponding non-internal name
10270
10271       ------------------------
10272       --  Non_Internal_Name --
10273       ------------------------
10274
10275       function Non_Internal_Name (E : Entity_Id) return Name_Id is
10276       begin
10277          Get_Name_String (Chars (E));
10278          Name_Len := Name_Len - 1;
10279          return Name_Find;
10280       end Non_Internal_Name;
10281
10282    --  Start of processing for Primitive_Names_Match
10283
10284    begin
10285       pragma Assert (Present (E1) and then Present (E2));
10286
10287       return Chars (E1) = Chars (E2)
10288         or else
10289            (not Is_Internal_Name (Chars (E1))
10290               and then Is_Internal_Name (Chars (E2))
10291               and then Non_Internal_Name (E2) = Chars (E1))
10292         or else
10293            (not Is_Internal_Name (Chars (E2))
10294               and then Is_Internal_Name (Chars (E1))
10295               and then Non_Internal_Name (E1) = Chars (E2))
10296         or else
10297            (Is_Predefined_Dispatching_Operation (E1)
10298               and then Is_Predefined_Dispatching_Operation (E2)
10299               and then Same_TSS (E1, E2))
10300         or else
10301            (Is_Init_Proc (E1) and then Is_Init_Proc (E2));
10302    end Primitive_Names_Match;
10303
10304    -----------------------
10305    -- Process_End_Label --
10306    -----------------------
10307
10308    procedure Process_End_Label
10309      (N   : Node_Id;
10310       Typ : Character;
10311       Ent  : Entity_Id)
10312    is
10313       Loc  : Source_Ptr;
10314       Nam  : Node_Id;
10315       Scop : Entity_Id;
10316
10317       Label_Ref : Boolean;
10318       --  Set True if reference to end label itself is required
10319
10320       Endl : Node_Id;
10321       --  Gets set to the operator symbol or identifier that references the
10322       --  entity Ent. For the child unit case, this is the identifier from the
10323       --  designator. For other cases, this is simply Endl.
10324
10325       procedure Generate_Parent_Ref (N : Node_Id; E : Entity_Id);
10326       --  N is an identifier node that appears as a parent unit reference in
10327       --  the case where Ent is a child unit. This procedure generates an
10328       --  appropriate cross-reference entry. E is the corresponding entity.
10329
10330       -------------------------
10331       -- Generate_Parent_Ref --
10332       -------------------------
10333
10334       procedure Generate_Parent_Ref (N : Node_Id; E : Entity_Id) is
10335       begin
10336          --  If names do not match, something weird, skip reference
10337
10338          if Chars (E) = Chars (N) then
10339
10340             --  Generate the reference. We do NOT consider this as a reference
10341             --  for unreferenced symbol purposes.
10342
10343             Generate_Reference (E, N, 'r', Set_Ref => False, Force => True);
10344
10345             if Style_Check then
10346                Style.Check_Identifier (N, E);
10347             end if;
10348          end if;
10349       end Generate_Parent_Ref;
10350
10351    --  Start of processing for Process_End_Label
10352
10353    begin
10354       --  If no node, ignore. This happens in some error situations, and
10355       --  also for some internally generated structures where no end label
10356       --  references are required in any case.
10357
10358       if No (N) then
10359          return;
10360       end if;
10361
10362       --  Nothing to do if no End_Label, happens for internally generated
10363       --  constructs where we don't want an end label reference anyway. Also
10364       --  nothing to do if Endl is a string literal, which means there was
10365       --  some prior error (bad operator symbol)
10366
10367       Endl := End_Label (N);
10368
10369       if No (Endl) or else Nkind (Endl) = N_String_Literal then
10370          return;
10371       end if;
10372
10373       --  Reference node is not in extended main source unit
10374
10375       if not In_Extended_Main_Source_Unit (N) then
10376
10377          --  Generally we do not collect references except for the extended
10378          --  main source unit. The one exception is the 'e' entry for a
10379          --  package spec, where it is useful for a client to have the
10380          --  ending information to define scopes.
10381
10382          if Typ /= 'e' then
10383             return;
10384
10385          else
10386             Label_Ref := False;
10387
10388             --  For this case, we can ignore any parent references, but we
10389             --  need the package name itself for the 'e' entry.
10390
10391             if Nkind (Endl) = N_Designator then
10392                Endl := Identifier (Endl);
10393             end if;
10394          end if;
10395
10396       --  Reference is in extended main source unit
10397
10398       else
10399          Label_Ref := True;
10400
10401          --  For designator, generate references for the parent entries
10402
10403          if Nkind (Endl) = N_Designator then
10404
10405             --  Generate references for the prefix if the END line comes from
10406             --  source (otherwise we do not need these references) We climb the
10407             --  scope stack to find the expected entities.
10408
10409             if Comes_From_Source (Endl) then
10410                Nam  := Name (Endl);
10411                Scop := Current_Scope;
10412                while Nkind (Nam) = N_Selected_Component loop
10413                   Scop := Scope (Scop);
10414                   exit when No (Scop);
10415                   Generate_Parent_Ref (Selector_Name (Nam), Scop);
10416                   Nam := Prefix (Nam);
10417                end loop;
10418
10419                if Present (Scop) then
10420                   Generate_Parent_Ref (Nam, Scope (Scop));
10421                end if;
10422             end if;
10423
10424             Endl := Identifier (Endl);
10425          end if;
10426       end if;
10427
10428       --  If the end label is not for the given entity, then either we have
10429       --  some previous error, or this is a generic instantiation for which
10430       --  we do not need to make a cross-reference in this case anyway. In
10431       --  either case we simply ignore the call.
10432
10433       if Chars (Ent) /= Chars (Endl) then
10434          return;
10435       end if;
10436
10437       --  If label was really there, then generate a normal reference and then
10438       --  adjust the location in the end label to point past the name (which
10439       --  should almost always be the semicolon).
10440
10441       Loc := Sloc (Endl);
10442
10443       if Comes_From_Source (Endl) then
10444
10445          --  If a label reference is required, then do the style check and
10446          --  generate an l-type cross-reference entry for the label
10447
10448          if Label_Ref then
10449             if Style_Check then
10450                Style.Check_Identifier (Endl, Ent);
10451             end if;
10452
10453             Generate_Reference (Ent, Endl, 'l', Set_Ref => False);
10454          end if;
10455
10456          --  Set the location to point past the label (normally this will
10457          --  mean the semicolon immediately following the label). This is
10458          --  done for the sake of the 'e' or 't' entry generated below.
10459
10460          Get_Decoded_Name_String (Chars (Endl));
10461          Set_Sloc (Endl, Sloc (Endl) + Source_Ptr (Name_Len));
10462       end if;
10463
10464       --  Now generate the e/t reference
10465
10466       Generate_Reference (Ent, Endl, Typ, Set_Ref => False, Force => True);
10467
10468       --  Restore Sloc, in case modified above, since we have an identifier
10469       --  and the normal Sloc should be left set in the tree.
10470
10471       Set_Sloc (Endl, Loc);
10472    end Process_End_Label;
10473
10474    ------------------------------------
10475    -- References_Generic_Formal_Type --
10476    ------------------------------------
10477
10478    function References_Generic_Formal_Type (N : Node_Id) return Boolean is
10479
10480       function Process (N : Node_Id) return Traverse_Result;
10481       --  Process one node in search for generic formal type
10482
10483       -------------
10484       -- Process --
10485       -------------
10486
10487       function Process (N : Node_Id) return Traverse_Result is
10488       begin
10489          if Nkind (N) in N_Has_Entity then
10490             declare
10491                E : constant Entity_Id := Entity (N);
10492             begin
10493                if Present (E) then
10494                   if Is_Generic_Type (E) then
10495                      return Abandon;
10496                   elsif Present (Etype (E))
10497                     and then Is_Generic_Type (Etype (E))
10498                   then
10499                      return Abandon;
10500                   end if;
10501                end if;
10502             end;
10503          end if;
10504
10505          return Atree.OK;
10506       end Process;
10507
10508       function Traverse is new Traverse_Func (Process);
10509       --  Traverse tree to look for generic type
10510
10511    begin
10512       if Inside_A_Generic then
10513          return Traverse (N) = Abandon;
10514       else
10515          return False;
10516       end if;
10517    end References_Generic_Formal_Type;
10518
10519    --------------------
10520    -- Remove_Homonym --
10521    --------------------
10522
10523    procedure Remove_Homonym (E : Entity_Id) is
10524       Prev  : Entity_Id := Empty;
10525       H     : Entity_Id;
10526
10527    begin
10528       if E = Current_Entity (E) then
10529          if Present (Homonym (E)) then
10530             Set_Current_Entity (Homonym (E));
10531          else
10532             Set_Name_Entity_Id (Chars (E), Empty);
10533          end if;
10534       else
10535          H := Current_Entity (E);
10536          while Present (H) and then H /= E loop
10537             Prev := H;
10538             H    := Homonym (H);
10539          end loop;
10540
10541          Set_Homonym (Prev, Homonym (E));
10542       end if;
10543    end Remove_Homonym;
10544
10545    ---------------------
10546    -- Rep_To_Pos_Flag --
10547    ---------------------
10548
10549    function Rep_To_Pos_Flag (E : Entity_Id; Loc : Source_Ptr) return Node_Id is
10550    begin
10551       return New_Occurrence_Of
10552                (Boolean_Literals (not Range_Checks_Suppressed (E)), Loc);
10553    end Rep_To_Pos_Flag;
10554
10555    --------------------
10556    -- Require_Entity --
10557    --------------------
10558
10559    procedure Require_Entity (N : Node_Id) is
10560    begin
10561       if Is_Entity_Name (N) and then No (Entity (N)) then
10562          if Total_Errors_Detected /= 0 then
10563             Set_Entity (N, Any_Id);
10564          else
10565             raise Program_Error;
10566          end if;
10567       end if;
10568    end Require_Entity;
10569
10570    ------------------------------
10571    -- Requires_Transient_Scope --
10572    ------------------------------
10573
10574    --  A transient scope is required when variable-sized temporaries are
10575    --  allocated in the primary or secondary stack, or when finalization
10576    --  actions must be generated before the next instruction.
10577
10578    function Requires_Transient_Scope (Id : Entity_Id) return Boolean is
10579       Typ : constant Entity_Id := Underlying_Type (Id);
10580
10581    --  Start of processing for Requires_Transient_Scope
10582
10583    begin
10584       --  This is a private type which is not completed yet. This can only
10585       --  happen in a default expression (of a formal parameter or of a
10586       --  record component). Do not expand transient scope in this case
10587
10588       if No (Typ) then
10589          return False;
10590
10591       --  Do not expand transient scope for non-existent procedure return
10592
10593       elsif Typ = Standard_Void_Type then
10594          return False;
10595
10596       --  Elementary types do not require a transient scope
10597
10598       elsif Is_Elementary_Type (Typ) then
10599          return False;
10600
10601       --  Generally, indefinite subtypes require a transient scope, since the
10602       --  back end cannot generate temporaries, since this is not a valid type
10603       --  for declaring an object. It might be possible to relax this in the
10604       --  future, e.g. by declaring the maximum possible space for the type.
10605
10606       elsif Is_Indefinite_Subtype (Typ) then
10607          return True;
10608
10609       --  Functions returning tagged types may dispatch on result so their
10610       --  returned value is allocated on the secondary stack. Controlled
10611       --  type temporaries need finalization.
10612
10613       elsif Is_Tagged_Type (Typ)
10614         or else Has_Controlled_Component (Typ)
10615       then
10616          return not Is_Value_Type (Typ);
10617
10618       --  Record type
10619
10620       elsif Is_Record_Type (Typ) then
10621          declare
10622             Comp : Entity_Id;
10623          begin
10624             Comp := First_Entity (Typ);
10625             while Present (Comp) loop
10626                if Ekind (Comp) = E_Component
10627                   and then Requires_Transient_Scope (Etype (Comp))
10628                then
10629                   return True;
10630                else
10631                   Next_Entity (Comp);
10632                end if;
10633             end loop;
10634          end;
10635
10636          return False;
10637
10638       --  String literal types never require transient scope
10639
10640       elsif Ekind (Typ) = E_String_Literal_Subtype then
10641          return False;
10642
10643       --  Array type. Note that we already know that this is a constrained
10644       --  array, since unconstrained arrays will fail the indefinite test.
10645
10646       elsif Is_Array_Type (Typ) then
10647
10648          --  If component type requires a transient scope, the array does too
10649
10650          if Requires_Transient_Scope (Component_Type (Typ)) then
10651             return True;
10652
10653          --  Otherwise, we only need a transient scope if the size depends on
10654          --  the value of one or more discriminants.
10655
10656          else
10657             return Size_Depends_On_Discriminant (Typ);
10658          end if;
10659
10660       --  All other cases do not require a transient scope
10661
10662       else
10663          return False;
10664       end if;
10665    end Requires_Transient_Scope;
10666
10667    --------------------------
10668    -- Reset_Analyzed_Flags --
10669    --------------------------
10670
10671    procedure Reset_Analyzed_Flags (N : Node_Id) is
10672
10673       function Clear_Analyzed (N : Node_Id) return Traverse_Result;
10674       --  Function used to reset Analyzed flags in tree. Note that we do
10675       --  not reset Analyzed flags in entities, since there is no need to
10676       --  reanalyze entities, and indeed, it is wrong to do so, since it
10677       --  can result in generating auxiliary stuff more than once.
10678
10679       --------------------
10680       -- Clear_Analyzed --
10681       --------------------
10682
10683       function Clear_Analyzed (N : Node_Id) return Traverse_Result is
10684       begin
10685          if not Has_Extension (N) then
10686             Set_Analyzed (N, False);
10687          end if;
10688
10689          return OK;
10690       end Clear_Analyzed;
10691
10692       procedure Reset_Analyzed is new Traverse_Proc (Clear_Analyzed);
10693
10694    --  Start of processing for Reset_Analyzed_Flags
10695
10696    begin
10697       Reset_Analyzed (N);
10698    end Reset_Analyzed_Flags;
10699
10700    ---------------------------
10701    -- Safe_To_Capture_Value --
10702    ---------------------------
10703
10704    function Safe_To_Capture_Value
10705      (N    : Node_Id;
10706       Ent  : Entity_Id;
10707       Cond : Boolean := False) return Boolean
10708    is
10709    begin
10710       --  The only entities for which we track constant values are variables
10711       --  which are not renamings, constants, out parameters, and in out
10712       --  parameters, so check if we have this case.
10713
10714       --  Note: it may seem odd to track constant values for constants, but in
10715       --  fact this routine is used for other purposes than simply capturing
10716       --  the value. In particular, the setting of Known[_Non]_Null.
10717
10718       if (Ekind (Ent) = E_Variable and then No (Renamed_Object (Ent)))
10719             or else
10720           Ekind (Ent) = E_Constant
10721             or else
10722           Ekind (Ent) = E_Out_Parameter
10723             or else
10724           Ekind (Ent) = E_In_Out_Parameter
10725       then
10726          null;
10727
10728       --  For conditionals, we also allow loop parameters and all formals,
10729       --  including in parameters.
10730
10731       elsif Cond
10732         and then
10733           (Ekind (Ent) = E_Loop_Parameter
10734              or else
10735            Ekind (Ent) = E_In_Parameter)
10736       then
10737          null;
10738
10739       --  For all other cases, not just unsafe, but impossible to capture
10740       --  Current_Value, since the above are the only entities which have
10741       --  Current_Value fields.
10742
10743       else
10744          return False;
10745       end if;
10746
10747       --  Skip if volatile or aliased, since funny things might be going on in
10748       --  these cases which we cannot necessarily track. Also skip any variable
10749       --  for which an address clause is given, or whose address is taken. Also
10750       --  never capture value of library level variables (an attempt to do so
10751       --  can occur in the case of package elaboration code).
10752
10753       if Treat_As_Volatile (Ent)
10754         or else Is_Aliased (Ent)
10755         or else Present (Address_Clause (Ent))
10756         or else Address_Taken (Ent)
10757         or else (Is_Library_Level_Entity (Ent)
10758                    and then Ekind (Ent) = E_Variable)
10759       then
10760          return False;
10761       end if;
10762
10763       --  OK, all above conditions are met. We also require that the scope of
10764       --  the reference be the same as the scope of the entity, not counting
10765       --  packages and blocks and loops.
10766
10767       declare
10768          E_Scope : constant Entity_Id := Scope (Ent);
10769          R_Scope : Entity_Id;
10770
10771       begin
10772          R_Scope := Current_Scope;
10773          while R_Scope /= Standard_Standard loop
10774             exit when R_Scope = E_Scope;
10775
10776             if not Ekind_In (R_Scope, E_Package, E_Block, E_Loop) then
10777                return False;
10778             else
10779                R_Scope := Scope (R_Scope);
10780             end if;
10781          end loop;
10782       end;
10783
10784       --  We also require that the reference does not appear in a context
10785       --  where it is not sure to be executed (i.e. a conditional context
10786       --  or an exception handler). We skip this if Cond is True, since the
10787       --  capturing of values from conditional tests handles this ok.
10788
10789       if Cond then
10790          return True;
10791       end if;
10792
10793       declare
10794          Desc : Node_Id;
10795          P    : Node_Id;
10796
10797       begin
10798          Desc := N;
10799
10800          P := Parent (N);
10801          while Present (P) loop
10802             if         Nkind (P) = N_If_Statement
10803               or else  Nkind (P) = N_Case_Statement
10804               or else (Nkind (P) in N_Short_Circuit
10805                          and then Desc = Right_Opnd (P))
10806               or else (Nkind (P) = N_Conditional_Expression
10807                          and then Desc /= First (Expressions (P)))
10808               or else  Nkind (P) = N_Exception_Handler
10809               or else  Nkind (P) = N_Selective_Accept
10810               or else  Nkind (P) = N_Conditional_Entry_Call
10811               or else  Nkind (P) = N_Timed_Entry_Call
10812               or else  Nkind (P) = N_Asynchronous_Select
10813             then
10814                return False;
10815             else
10816                Desc := P;
10817                P    := Parent (P);
10818             end if;
10819          end loop;
10820       end;
10821
10822       --  OK, looks safe to set value
10823
10824       return True;
10825    end Safe_To_Capture_Value;
10826
10827    ---------------
10828    -- Same_Name --
10829    ---------------
10830
10831    function Same_Name (N1, N2 : Node_Id) return Boolean is
10832       K1 : constant Node_Kind := Nkind (N1);
10833       K2 : constant Node_Kind := Nkind (N2);
10834
10835    begin
10836       if (K1 = N_Identifier or else K1 = N_Defining_Identifier)
10837         and then (K2 = N_Identifier or else K2 = N_Defining_Identifier)
10838       then
10839          return Chars (N1) = Chars (N2);
10840
10841       elsif (K1 = N_Selected_Component or else K1 = N_Expanded_Name)
10842         and then (K2 = N_Selected_Component or else K2 = N_Expanded_Name)
10843       then
10844          return Same_Name (Selector_Name (N1), Selector_Name (N2))
10845            and then Same_Name (Prefix (N1), Prefix (N2));
10846
10847       else
10848          return False;
10849       end if;
10850    end Same_Name;
10851
10852    -----------------
10853    -- Same_Object --
10854    -----------------
10855
10856    function Same_Object (Node1, Node2 : Node_Id) return Boolean is
10857       N1 : constant Node_Id := Original_Node (Node1);
10858       N2 : constant Node_Id := Original_Node (Node2);
10859       --  We do the tests on original nodes, since we are most interested
10860       --  in the original source, not any expansion that got in the way.
10861
10862       K1 : constant Node_Kind := Nkind (N1);
10863       K2 : constant Node_Kind := Nkind (N2);
10864
10865    begin
10866       --  First case, both are entities with same entity
10867
10868       if K1 in N_Has_Entity and then K2 in N_Has_Entity then
10869          declare
10870             EN1 : constant Entity_Id := Entity (N1);
10871             EN2 : constant Entity_Id := Entity (N2);
10872          begin
10873             if Present (EN1) and then Present (EN2)
10874               and then (Ekind_In (EN1, E_Variable, E_Constant)
10875                          or else Is_Formal (EN1))
10876               and then EN1 = EN2
10877             then
10878                return True;
10879             end if;
10880          end;
10881       end if;
10882
10883       --  Second case, selected component with same selector, same record
10884
10885       if K1 = N_Selected_Component
10886         and then K2 = N_Selected_Component
10887         and then Chars (Selector_Name (N1)) = Chars (Selector_Name (N2))
10888       then
10889          return Same_Object (Prefix (N1), Prefix (N2));
10890
10891       --  Third case, indexed component with same subscripts, same array
10892
10893       elsif K1 = N_Indexed_Component
10894         and then K2 = N_Indexed_Component
10895         and then Same_Object (Prefix (N1), Prefix (N2))
10896       then
10897          declare
10898             E1, E2 : Node_Id;
10899          begin
10900             E1 := First (Expressions (N1));
10901             E2 := First (Expressions (N2));
10902             while Present (E1) loop
10903                if not Same_Value (E1, E2) then
10904                   return False;
10905                else
10906                   Next (E1);
10907                   Next (E2);
10908                end if;
10909             end loop;
10910
10911             return True;
10912          end;
10913
10914       --  Fourth case, slice of same array with same bounds
10915
10916       elsif K1 = N_Slice
10917         and then K2 = N_Slice
10918         and then Nkind (Discrete_Range (N1)) = N_Range
10919         and then Nkind (Discrete_Range (N2)) = N_Range
10920         and then Same_Value (Low_Bound (Discrete_Range (N1)),
10921                              Low_Bound (Discrete_Range (N2)))
10922         and then Same_Value (High_Bound (Discrete_Range (N1)),
10923                              High_Bound (Discrete_Range (N2)))
10924       then
10925          return Same_Name (Prefix (N1), Prefix (N2));
10926
10927       --  All other cases, not clearly the same object
10928
10929       else
10930          return False;
10931       end if;
10932    end Same_Object;
10933
10934    ---------------
10935    -- Same_Type --
10936    ---------------
10937
10938    function Same_Type (T1, T2 : Entity_Id) return Boolean is
10939    begin
10940       if T1 = T2 then
10941          return True;
10942
10943       elsif not Is_Constrained (T1)
10944         and then not Is_Constrained (T2)
10945         and then Base_Type (T1) = Base_Type (T2)
10946       then
10947          return True;
10948
10949       --  For now don't bother with case of identical constraints, to be
10950       --  fiddled with later on perhaps (this is only used for optimization
10951       --  purposes, so it is not critical to do a best possible job)
10952
10953       else
10954          return False;
10955       end if;
10956    end Same_Type;
10957
10958    ----------------
10959    -- Same_Value --
10960    ----------------
10961
10962    function Same_Value (Node1, Node2 : Node_Id) return Boolean is
10963    begin
10964       if Compile_Time_Known_Value (Node1)
10965         and then Compile_Time_Known_Value (Node2)
10966         and then Expr_Value (Node1) = Expr_Value (Node2)
10967       then
10968          return True;
10969       elsif Same_Object (Node1, Node2) then
10970          return True;
10971       else
10972          return False;
10973       end if;
10974    end Same_Value;
10975
10976    -----------------
10977    -- Save_Actual --
10978    -----------------
10979
10980    procedure Save_Actual (N : Node_Id;  Writable : Boolean := False) is
10981    begin
10982       if Ada_Version < Ada_2012 then
10983          return;
10984
10985       elsif Is_Entity_Name (N)
10986         or else
10987           Nkind_In (N, N_Indexed_Component, N_Selected_Component, N_Slice)
10988         or else
10989           (Nkind (N) = N_Attribute_Reference
10990             and then Attribute_Name (N) = Name_Access)
10991
10992       then
10993          --  We are only interested in IN OUT parameters of inner calls
10994
10995          if not Writable
10996            or else Nkind (Parent (N)) = N_Function_Call
10997            or else Nkind (Parent (N)) in N_Op
10998          then
10999             Actuals_In_Call.Increment_Last;
11000             Actuals_In_Call.Table (Actuals_In_Call.Last) := (N, Writable);
11001          end if;
11002       end if;
11003    end Save_Actual;
11004
11005    ------------------------
11006    -- Scope_Is_Transient --
11007    ------------------------
11008
11009    function Scope_Is_Transient return Boolean is
11010    begin
11011       return Scope_Stack.Table (Scope_Stack.Last).Is_Transient;
11012    end Scope_Is_Transient;
11013
11014    ------------------
11015    -- Scope_Within --
11016    ------------------
11017
11018    function Scope_Within (Scope1, Scope2 : Entity_Id) return Boolean is
11019       Scop : Entity_Id;
11020
11021    begin
11022       Scop := Scope1;
11023       while Scop /= Standard_Standard loop
11024          Scop := Scope (Scop);
11025
11026          if Scop = Scope2 then
11027             return True;
11028          end if;
11029       end loop;
11030
11031       return False;
11032    end Scope_Within;
11033
11034    --------------------------
11035    -- Scope_Within_Or_Same --
11036    --------------------------
11037
11038    function Scope_Within_Or_Same (Scope1, Scope2 : Entity_Id) return Boolean is
11039       Scop : Entity_Id;
11040
11041    begin
11042       Scop := Scope1;
11043       while Scop /= Standard_Standard loop
11044          if Scop = Scope2 then
11045             return True;
11046          else
11047             Scop := Scope (Scop);
11048          end if;
11049       end loop;
11050
11051       return False;
11052    end Scope_Within_Or_Same;
11053
11054    --------------------
11055    -- Set_Convention --
11056    --------------------
11057
11058    procedure Set_Convention (E : Entity_Id; Val : Snames.Convention_Id) is
11059    begin
11060       Basic_Set_Convention (E, Val);
11061
11062       if Is_Type (E)
11063         and then Is_Access_Subprogram_Type (Base_Type (E))
11064         and then Has_Foreign_Convention (E)
11065       then
11066          Set_Can_Use_Internal_Rep (E, False);
11067       end if;
11068    end Set_Convention;
11069
11070    ------------------------
11071    -- Set_Current_Entity --
11072    ------------------------
11073
11074    --  The given entity is to be set as the currently visible definition
11075    --  of its associated name (i.e. the Node_Id associated with its name).
11076    --  All we have to do is to get the name from the identifier, and
11077    --  then set the associated Node_Id to point to the given entity.
11078
11079    procedure Set_Current_Entity (E : Entity_Id) is
11080    begin
11081       Set_Name_Entity_Id (Chars (E), E);
11082    end Set_Current_Entity;
11083
11084    ---------------------------
11085    -- Set_Debug_Info_Needed --
11086    ---------------------------
11087
11088    procedure Set_Debug_Info_Needed (T : Entity_Id) is
11089
11090       procedure Set_Debug_Info_Needed_If_Not_Set (E : Entity_Id);
11091       pragma Inline (Set_Debug_Info_Needed_If_Not_Set);
11092       --  Used to set debug info in a related node if not set already
11093
11094       --------------------------------------
11095       -- Set_Debug_Info_Needed_If_Not_Set --
11096       --------------------------------------
11097
11098       procedure Set_Debug_Info_Needed_If_Not_Set (E : Entity_Id) is
11099       begin
11100          if Present (E)
11101            and then not Needs_Debug_Info (E)
11102          then
11103             Set_Debug_Info_Needed (E);
11104
11105             --  For a private type, indicate that the full view also needs
11106             --  debug information.
11107
11108             if Is_Type (E)
11109               and then Is_Private_Type (E)
11110               and then Present (Full_View (E))
11111             then
11112                Set_Debug_Info_Needed (Full_View (E));
11113             end if;
11114          end if;
11115       end Set_Debug_Info_Needed_If_Not_Set;
11116
11117    --  Start of processing for Set_Debug_Info_Needed
11118
11119    begin
11120       --  Nothing to do if argument is Empty or has Debug_Info_Off set, which
11121       --  indicates that Debug_Info_Needed is never required for the entity.
11122
11123       if No (T)
11124         or else Debug_Info_Off (T)
11125       then
11126          return;
11127       end if;
11128
11129       --  Set flag in entity itself. Note that we will go through the following
11130       --  circuitry even if the flag is already set on T. That's intentional,
11131       --  it makes sure that the flag will be set in subsidiary entities.
11132
11133       Set_Needs_Debug_Info (T);
11134
11135       --  Set flag on subsidiary entities if not set already
11136
11137       if Is_Object (T) then
11138          Set_Debug_Info_Needed_If_Not_Set (Etype (T));
11139
11140       elsif Is_Type (T) then
11141          Set_Debug_Info_Needed_If_Not_Set (Etype (T));
11142
11143          if Is_Record_Type (T) then
11144             declare
11145                Ent : Entity_Id := First_Entity (T);
11146             begin
11147                while Present (Ent) loop
11148                   Set_Debug_Info_Needed_If_Not_Set (Ent);
11149                   Next_Entity (Ent);
11150                end loop;
11151             end;
11152
11153             --  For a class wide subtype, we also need debug information
11154             --  for the equivalent type.
11155
11156             if Ekind (T) = E_Class_Wide_Subtype then
11157                Set_Debug_Info_Needed_If_Not_Set (Equivalent_Type (T));
11158             end if;
11159
11160          elsif Is_Array_Type (T) then
11161             Set_Debug_Info_Needed_If_Not_Set (Component_Type (T));
11162
11163             declare
11164                Indx : Node_Id := First_Index (T);
11165             begin
11166                while Present (Indx) loop
11167                   Set_Debug_Info_Needed_If_Not_Set (Etype (Indx));
11168                   Indx := Next_Index (Indx);
11169                end loop;
11170             end;
11171
11172             if Is_Packed (T) then
11173                Set_Debug_Info_Needed_If_Not_Set (Packed_Array_Type (T));
11174             end if;
11175
11176          elsif Is_Access_Type (T) then
11177             Set_Debug_Info_Needed_If_Not_Set (Directly_Designated_Type (T));
11178
11179          elsif Is_Private_Type (T) then
11180             Set_Debug_Info_Needed_If_Not_Set (Full_View (T));
11181
11182          elsif Is_Protected_Type (T) then
11183             Set_Debug_Info_Needed_If_Not_Set (Corresponding_Record_Type (T));
11184          end if;
11185       end if;
11186    end Set_Debug_Info_Needed;
11187
11188    ---------------------------------
11189    -- Set_Entity_With_Style_Check --
11190    ---------------------------------
11191
11192    procedure Set_Entity_With_Style_Check (N : Node_Id; Val : Entity_Id) is
11193       Val_Actual : Entity_Id;
11194       Nod        : Node_Id;
11195
11196    begin
11197       Set_Entity (N, Val);
11198
11199       if Style_Check
11200         and then not Suppress_Style_Checks (Val)
11201         and then not In_Instance
11202       then
11203          if Nkind (N) = N_Identifier then
11204             Nod := N;
11205          elsif Nkind (N) = N_Expanded_Name then
11206             Nod := Selector_Name (N);
11207          else
11208             return;
11209          end if;
11210
11211          --  A special situation arises for derived operations, where we want
11212          --  to do the check against the parent (since the Sloc of the derived
11213          --  operation points to the derived type declaration itself).
11214
11215          Val_Actual := Val;
11216          while not Comes_From_Source (Val_Actual)
11217            and then Nkind (Val_Actual) in N_Entity
11218            and then (Ekind (Val_Actual) = E_Enumeration_Literal
11219                       or else Is_Subprogram (Val_Actual)
11220                       or else Is_Generic_Subprogram (Val_Actual))
11221            and then Present (Alias (Val_Actual))
11222          loop
11223             Val_Actual := Alias (Val_Actual);
11224          end loop;
11225
11226          --  Renaming declarations for generic actuals do not come from source,
11227          --  and have a different name from that of the entity they rename, so
11228          --  there is no style check to perform here.
11229
11230          if Chars (Nod) = Chars (Val_Actual) then
11231             Style.Check_Identifier (Nod, Val_Actual);
11232          end if;
11233       end if;
11234
11235       Set_Entity (N, Val);
11236    end Set_Entity_With_Style_Check;
11237
11238    ------------------------
11239    -- Set_Name_Entity_Id --
11240    ------------------------
11241
11242    procedure Set_Name_Entity_Id (Id : Name_Id; Val : Entity_Id) is
11243    begin
11244       Set_Name_Table_Info (Id, Int (Val));
11245    end Set_Name_Entity_Id;
11246
11247    ---------------------
11248    -- Set_Next_Actual --
11249    ---------------------
11250
11251    procedure Set_Next_Actual (Ass1_Id : Node_Id; Ass2_Id : Node_Id) is
11252    begin
11253       if Nkind (Parent (Ass1_Id)) = N_Parameter_Association then
11254          Set_First_Named_Actual (Parent (Ass1_Id), Ass2_Id);
11255       end if;
11256    end Set_Next_Actual;
11257
11258    ----------------------------------
11259    -- Set_Optimize_Alignment_Flags --
11260    ----------------------------------
11261
11262    procedure Set_Optimize_Alignment_Flags (E : Entity_Id) is
11263    begin
11264       if Optimize_Alignment = 'S' then
11265          Set_Optimize_Alignment_Space (E);
11266       elsif Optimize_Alignment = 'T' then
11267          Set_Optimize_Alignment_Time (E);
11268       end if;
11269    end Set_Optimize_Alignment_Flags;
11270
11271    -----------------------
11272    -- Set_Public_Status --
11273    -----------------------
11274
11275    procedure Set_Public_Status (Id : Entity_Id) is
11276       S : constant Entity_Id := Current_Scope;
11277
11278       function Within_HSS_Or_If (E : Entity_Id) return Boolean;
11279       --  Determines if E is defined within handled statement sequence or
11280       --  an if statement, returns True if so, False otherwise.
11281
11282       ----------------------
11283       -- Within_HSS_Or_If --
11284       ----------------------
11285
11286       function Within_HSS_Or_If (E : Entity_Id) return Boolean is
11287          N : Node_Id;
11288       begin
11289          N := Declaration_Node (E);
11290          loop
11291             N := Parent (N);
11292
11293             if No (N) then
11294                return False;
11295
11296             elsif Nkind_In (N, N_Handled_Sequence_Of_Statements,
11297                                N_If_Statement)
11298             then
11299                return True;
11300             end if;
11301          end loop;
11302       end Within_HSS_Or_If;
11303
11304    --  Start of processing for Set_Public_Status
11305
11306    begin
11307       --  Everything in the scope of Standard is public
11308
11309       if S = Standard_Standard then
11310          Set_Is_Public (Id);
11311
11312       --  Entity is definitely not public if enclosing scope is not public
11313
11314       elsif not Is_Public (S) then
11315          return;
11316
11317       --  An object or function declaration that occurs in a handled sequence
11318       --  of statements or within an if statement is the declaration for a
11319       --  temporary object or local subprogram generated by the expander. It
11320       --  never needs to be made public and furthermore, making it public can
11321       --  cause back end problems.
11322
11323       elsif Nkind_In (Parent (Id), N_Object_Declaration,
11324                                    N_Function_Specification)
11325         and then Within_HSS_Or_If (Id)
11326       then
11327          return;
11328
11329       --  Entities in public packages or records are public
11330
11331       elsif Ekind (S) = E_Package or Is_Record_Type (S) then
11332          Set_Is_Public (Id);
11333
11334       --  The bounds of an entry family declaration can generate object
11335       --  declarations that are visible to the back-end, e.g. in the
11336       --  the declaration of a composite type that contains tasks.
11337
11338       elsif Is_Concurrent_Type (S)
11339         and then not Has_Completion (S)
11340         and then Nkind (Parent (Id)) = N_Object_Declaration
11341       then
11342          Set_Is_Public (Id);
11343       end if;
11344    end Set_Public_Status;
11345
11346    -----------------------------
11347    -- Set_Referenced_Modified --
11348    -----------------------------
11349
11350    procedure Set_Referenced_Modified (N : Node_Id; Out_Param : Boolean) is
11351       Pref : Node_Id;
11352
11353    begin
11354       --  Deal with indexed or selected component where prefix is modified
11355
11356       if Nkind_In (N, N_Indexed_Component, N_Selected_Component) then
11357          Pref := Prefix (N);
11358
11359          --  If prefix is access type, then it is the designated object that is
11360          --  being modified, which means we have no entity to set the flag on.
11361
11362          if No (Etype (Pref)) or else Is_Access_Type (Etype (Pref)) then
11363             return;
11364
11365             --  Otherwise chase the prefix
11366
11367          else
11368             Set_Referenced_Modified (Pref, Out_Param);
11369          end if;
11370
11371       --  Otherwise see if we have an entity name (only other case to process)
11372
11373       elsif Is_Entity_Name (N) and then Present (Entity (N)) then
11374          Set_Referenced_As_LHS           (Entity (N), not Out_Param);
11375          Set_Referenced_As_Out_Parameter (Entity (N), Out_Param);
11376       end if;
11377    end Set_Referenced_Modified;
11378
11379    ----------------------------
11380    -- Set_Scope_Is_Transient --
11381    ----------------------------
11382
11383    procedure Set_Scope_Is_Transient (V : Boolean := True) is
11384    begin
11385       Scope_Stack.Table (Scope_Stack.Last).Is_Transient := V;
11386    end Set_Scope_Is_Transient;
11387
11388    -------------------
11389    -- Set_Size_Info --
11390    -------------------
11391
11392    procedure Set_Size_Info (T1, T2 : Entity_Id) is
11393    begin
11394       --  We copy Esize, but not RM_Size, since in general RM_Size is
11395       --  subtype specific and does not get inherited by all subtypes.
11396
11397       Set_Esize                     (T1, Esize                     (T2));
11398       Set_Has_Biased_Representation (T1, Has_Biased_Representation (T2));
11399
11400       if Is_Discrete_Or_Fixed_Point_Type (T1)
11401            and then
11402          Is_Discrete_Or_Fixed_Point_Type (T2)
11403       then
11404          Set_Is_Unsigned_Type       (T1, Is_Unsigned_Type          (T2));
11405       end if;
11406
11407       Set_Alignment                 (T1, Alignment                 (T2));
11408    end Set_Size_Info;
11409
11410    --------------------
11411    -- Static_Boolean --
11412    --------------------
11413
11414    function Static_Boolean (N : Node_Id) return Uint is
11415    begin
11416       Analyze_And_Resolve (N, Standard_Boolean);
11417
11418       if N = Error
11419         or else Error_Posted (N)
11420         or else Etype (N) = Any_Type
11421       then
11422          return No_Uint;
11423       end if;
11424
11425       if Is_Static_Expression (N) then
11426          if not Raises_Constraint_Error (N) then
11427             return Expr_Value (N);
11428          else
11429             return No_Uint;
11430          end if;
11431
11432       elsif Etype (N) = Any_Type then
11433          return No_Uint;
11434
11435       else
11436          Flag_Non_Static_Expr
11437            ("static boolean expression required here", N);
11438          return No_Uint;
11439       end if;
11440    end Static_Boolean;
11441
11442    --------------------
11443    -- Static_Integer --
11444    --------------------
11445
11446    function Static_Integer (N : Node_Id) return Uint is
11447    begin
11448       Analyze_And_Resolve (N, Any_Integer);
11449
11450       if N = Error
11451         or else Error_Posted (N)
11452         or else Etype (N) = Any_Type
11453       then
11454          return No_Uint;
11455       end if;
11456
11457       if Is_Static_Expression (N) then
11458          if not Raises_Constraint_Error (N) then
11459             return Expr_Value (N);
11460          else
11461             return No_Uint;
11462          end if;
11463
11464       elsif Etype (N) = Any_Type then
11465          return No_Uint;
11466
11467       else
11468          Flag_Non_Static_Expr
11469            ("static integer expression required here", N);
11470          return No_Uint;
11471       end if;
11472    end Static_Integer;
11473
11474    --------------------------
11475    -- Statically_Different --
11476    --------------------------
11477
11478    function Statically_Different (E1, E2 : Node_Id) return Boolean is
11479       R1 : constant Node_Id := Get_Referenced_Object (E1);
11480       R2 : constant Node_Id := Get_Referenced_Object (E2);
11481    begin
11482       return     Is_Entity_Name (R1)
11483         and then Is_Entity_Name (R2)
11484         and then Entity (R1) /= Entity (R2)
11485         and then not Is_Formal (Entity (R1))
11486         and then not Is_Formal (Entity (R2));
11487    end Statically_Different;
11488
11489    -----------------------------
11490    -- Subprogram_Access_Level --
11491    -----------------------------
11492
11493    function Subprogram_Access_Level (Subp : Entity_Id) return Uint is
11494    begin
11495       if Present (Alias (Subp)) then
11496          return Subprogram_Access_Level (Alias (Subp));
11497       else
11498          return Scope_Depth (Enclosing_Dynamic_Scope (Subp));
11499       end if;
11500    end Subprogram_Access_Level;
11501
11502    -----------------
11503    -- Trace_Scope --
11504    -----------------
11505
11506    procedure Trace_Scope (N : Node_Id; E : Entity_Id; Msg : String) is
11507    begin
11508       if Debug_Flag_W then
11509          for J in 0 .. Scope_Stack.Last loop
11510             Write_Str ("  ");
11511          end loop;
11512
11513          Write_Str (Msg);
11514          Write_Name (Chars (E));
11515          Write_Str (" from ");
11516          Write_Location (Sloc (N));
11517          Write_Eol;
11518       end if;
11519    end Trace_Scope;
11520
11521    -----------------------
11522    -- Transfer_Entities --
11523    -----------------------
11524
11525    procedure Transfer_Entities (From : Entity_Id; To : Entity_Id) is
11526       Ent : Entity_Id := First_Entity (From);
11527
11528    begin
11529       if No (Ent) then
11530          return;
11531       end if;
11532
11533       if (Last_Entity (To)) = Empty then
11534          Set_First_Entity (To, Ent);
11535       else
11536          Set_Next_Entity (Last_Entity (To), Ent);
11537       end if;
11538
11539       Set_Last_Entity (To, Last_Entity (From));
11540
11541       while Present (Ent) loop
11542          Set_Scope (Ent, To);
11543
11544          if not Is_Public (Ent) then
11545             Set_Public_Status (Ent);
11546
11547             if Is_Public (Ent)
11548               and then Ekind (Ent) = E_Record_Subtype
11549
11550             then
11551                --  The components of the propagated Itype must be public
11552                --  as well.
11553
11554                declare
11555                   Comp : Entity_Id;
11556                begin
11557                   Comp := First_Entity (Ent);
11558                   while Present (Comp) loop
11559                      Set_Is_Public (Comp);
11560                      Next_Entity (Comp);
11561                   end loop;
11562                end;
11563             end if;
11564          end if;
11565
11566          Next_Entity (Ent);
11567       end loop;
11568
11569       Set_First_Entity (From, Empty);
11570       Set_Last_Entity (From, Empty);
11571    end Transfer_Entities;
11572
11573    -----------------------
11574    -- Type_Access_Level --
11575    -----------------------
11576
11577    function Type_Access_Level (Typ : Entity_Id) return Uint is
11578       Btyp : Entity_Id;
11579
11580    begin
11581       Btyp := Base_Type (Typ);
11582
11583       --  Ada 2005 (AI-230): For most cases of anonymous access types, we
11584       --  simply use the level where the type is declared. This is true for
11585       --  stand-alone object declarations, and for anonymous access types
11586       --  associated with components the level is the same as that of the
11587       --  enclosing composite type. However, special treatment is needed for
11588       --  the cases of access parameters, return objects of an anonymous access
11589       --  type, and, in Ada 95, access discriminants of limited types.
11590
11591       if Ekind (Btyp) in Access_Kind then
11592          if Ekind (Btyp) = E_Anonymous_Access_Type then
11593
11594             --  If the type is a nonlocal anonymous access type (such as for
11595             --  an access parameter) we treat it as being declared at the
11596             --  library level to ensure that names such as X.all'access don't
11597             --  fail static accessibility checks.
11598
11599             if not Is_Local_Anonymous_Access (Typ) then
11600                return Scope_Depth (Standard_Standard);
11601
11602             --  If this is a return object, the accessibility level is that of
11603             --  the result subtype of the enclosing function. The test here is
11604             --  little complicated, because we have to account for extended
11605             --  return statements that have been rewritten as blocks, in which
11606             --  case we have to find and the Is_Return_Object attribute of the
11607             --  itype's associated object. It would be nice to find a way to
11608             --  simplify this test, but it doesn't seem worthwhile to add a new
11609             --  flag just for purposes of this test. ???
11610
11611             elsif Ekind (Scope (Btyp)) = E_Return_Statement
11612               or else
11613                 (Is_Itype (Btyp)
11614                   and then Nkind (Associated_Node_For_Itype (Btyp)) =
11615                              N_Object_Declaration
11616                   and then Is_Return_Object
11617                              (Defining_Identifier
11618                                 (Associated_Node_For_Itype (Btyp))))
11619             then
11620                declare
11621                   Scop : Entity_Id;
11622
11623                begin
11624                   Scop := Scope (Scope (Btyp));
11625                   while Present (Scop) loop
11626                      exit when Ekind (Scop) = E_Function;
11627                      Scop := Scope (Scop);
11628                   end loop;
11629
11630                   --  Treat the return object's type as having the level of the
11631                   --  function's result subtype (as per RM05-6.5(5.3/2)).
11632
11633                   return Type_Access_Level (Etype (Scop));
11634                end;
11635             end if;
11636          end if;
11637
11638          Btyp := Root_Type (Btyp);
11639
11640          --  The accessibility level of anonymous access types associated with
11641          --  discriminants is that of the current instance of the type, and
11642          --  that's deeper than the type itself (AARM 3.10.2 (12.3.21)).
11643
11644          --  AI-402: access discriminants have accessibility based on the
11645          --  object rather than the type in Ada 2005, so the above paragraph
11646          --  doesn't apply.
11647
11648          --  ??? Needs completion with rules from AI-416
11649
11650          if Ada_Version <= Ada_95
11651            and then Ekind (Typ) = E_Anonymous_Access_Type
11652            and then Present (Associated_Node_For_Itype (Typ))
11653            and then Nkind (Associated_Node_For_Itype (Typ)) =
11654                                                  N_Discriminant_Specification
11655          then
11656             return Scope_Depth (Enclosing_Dynamic_Scope (Btyp)) + 1;
11657          end if;
11658       end if;
11659
11660       return Scope_Depth (Enclosing_Dynamic_Scope (Btyp));
11661    end Type_Access_Level;
11662
11663    --------------------------
11664    -- Unit_Declaration_Node --
11665    --------------------------
11666
11667    function Unit_Declaration_Node (Unit_Id : Entity_Id) return Node_Id is
11668       N : Node_Id := Parent (Unit_Id);
11669
11670    begin
11671       --  Predefined operators do not have a full function declaration
11672
11673       if Ekind (Unit_Id) = E_Operator then
11674          return N;
11675       end if;
11676
11677       --  Isn't there some better way to express the following ???
11678
11679       while Nkind (N) /= N_Abstract_Subprogram_Declaration
11680         and then Nkind (N) /= N_Formal_Package_Declaration
11681         and then Nkind (N) /= N_Function_Instantiation
11682         and then Nkind (N) /= N_Generic_Package_Declaration
11683         and then Nkind (N) /= N_Generic_Subprogram_Declaration
11684         and then Nkind (N) /= N_Package_Declaration
11685         and then Nkind (N) /= N_Package_Body
11686         and then Nkind (N) /= N_Package_Instantiation
11687         and then Nkind (N) /= N_Package_Renaming_Declaration
11688         and then Nkind (N) /= N_Procedure_Instantiation
11689         and then Nkind (N) /= N_Protected_Body
11690         and then Nkind (N) /= N_Subprogram_Declaration
11691         and then Nkind (N) /= N_Subprogram_Body
11692         and then Nkind (N) /= N_Subprogram_Body_Stub
11693         and then Nkind (N) /= N_Subprogram_Renaming_Declaration
11694         and then Nkind (N) /= N_Task_Body
11695         and then Nkind (N) /= N_Task_Type_Declaration
11696         and then Nkind (N) not in N_Formal_Subprogram_Declaration
11697         and then Nkind (N) not in N_Generic_Renaming_Declaration
11698       loop
11699          N := Parent (N);
11700          pragma Assert (Present (N));
11701       end loop;
11702
11703       return N;
11704    end Unit_Declaration_Node;
11705
11706    ---------------------
11707    -- Unit_Is_Visible --
11708    ---------------------
11709
11710    function Unit_Is_Visible (U : Entity_Id) return Boolean is
11711       Curr        : constant Node_Id   := Cunit (Current_Sem_Unit);
11712       Curr_Entity : constant Entity_Id := Cunit_Entity (Current_Sem_Unit);
11713
11714       function Unit_In_Parent_Context (Par_Unit : Node_Id) return Boolean;
11715       --  For a child unit, check whether unit appears in a with_clause
11716       --  of a parent.
11717
11718       function Unit_In_Context (Comp_Unit : Node_Id) return Boolean;
11719       --  Scan the context clause of one compilation unit looking for a
11720       --  with_clause for the unit in question.
11721
11722       ----------------------------
11723       -- Unit_In_Parent_Context --
11724       ----------------------------
11725
11726       function Unit_In_Parent_Context (Par_Unit : Node_Id) return Boolean is
11727       begin
11728          if Unit_In_Context (Par_Unit) then
11729             return True;
11730
11731          elsif Is_Child_Unit (Defining_Entity (Unit (Par_Unit))) then
11732             return Unit_In_Parent_Context (Parent_Spec (Unit (Par_Unit)));
11733
11734          else
11735             return False;
11736          end if;
11737       end Unit_In_Parent_Context;
11738
11739       ---------------------
11740       -- Unit_In_Context --
11741       ---------------------
11742
11743       function Unit_In_Context (Comp_Unit : Node_Id) return Boolean is
11744          Clause : Node_Id;
11745
11746       begin
11747          Clause := First (Context_Items (Comp_Unit));
11748          while Present (Clause) loop
11749             if Nkind (Clause) = N_With_Clause then
11750                if Library_Unit (Clause) = U then
11751                   return True;
11752
11753                --  The with_clause may denote a renaming of the unit we are
11754                --  looking for, eg. Text_IO which renames Ada.Text_IO.
11755
11756                elsif
11757                  Renamed_Entity (Entity (Name (Clause))) =
11758                                                 Defining_Entity (Unit (U))
11759                then
11760                   return True;
11761                end if;
11762             end if;
11763
11764             Next (Clause);
11765          end loop;
11766
11767          return False;
11768       end Unit_In_Context;
11769
11770    --  Start of processing for Unit_Is_Visible
11771
11772    begin
11773       --  The currrent unit is directly visible.
11774
11775       if Curr = U then
11776          return True;
11777
11778       elsif Unit_In_Context (Curr) then
11779          return True;
11780
11781       --  If the current unit is a body, check the context of the spec.
11782
11783       elsif Nkind (Unit (Curr)) = N_Package_Body
11784         or else
11785           (Nkind (Unit (Curr)) = N_Subprogram_Body
11786             and then not Acts_As_Spec (Unit (Curr)))
11787       then
11788          if Unit_In_Context (Library_Unit (Curr)) then
11789             return True;
11790          end if;
11791       end if;
11792
11793       --  If the spec is a child unit, examine the parents.
11794
11795       if Is_Child_Unit (Curr_Entity) then
11796          if Nkind (Unit (Curr)) in N_Unit_Body then
11797             return
11798               Unit_In_Parent_Context
11799                 (Parent_Spec (Unit (Library_Unit (Curr))));
11800          else
11801             return Unit_In_Parent_Context (Parent_Spec (Unit (Curr)));
11802          end if;
11803
11804       else
11805          return False;
11806       end if;
11807    end Unit_Is_Visible;
11808
11809    ------------------------------
11810    -- Universal_Interpretation --
11811    ------------------------------
11812
11813    function Universal_Interpretation (Opnd : Node_Id) return Entity_Id is
11814       Index : Interp_Index;
11815       It    : Interp;
11816
11817    begin
11818       --  The argument may be a formal parameter of an operator or subprogram
11819       --  with multiple interpretations, or else an expression for an actual.
11820
11821       if Nkind (Opnd) = N_Defining_Identifier
11822         or else not Is_Overloaded (Opnd)
11823       then
11824          if Etype (Opnd) = Universal_Integer
11825            or else Etype (Opnd) = Universal_Real
11826          then
11827             return Etype (Opnd);
11828          else
11829             return Empty;
11830          end if;
11831
11832       else
11833          Get_First_Interp (Opnd, Index, It);
11834          while Present (It.Typ) loop
11835             if It.Typ = Universal_Integer
11836               or else It.Typ = Universal_Real
11837             then
11838                return It.Typ;
11839             end if;
11840
11841             Get_Next_Interp (Index, It);
11842          end loop;
11843
11844          return Empty;
11845       end if;
11846    end Universal_Interpretation;
11847
11848    ---------------
11849    -- Unqualify --
11850    ---------------
11851
11852    function Unqualify (Expr : Node_Id) return Node_Id is
11853    begin
11854       --  Recurse to handle unlikely case of multiple levels of qualification
11855
11856       if Nkind (Expr) = N_Qualified_Expression then
11857          return Unqualify (Expression (Expr));
11858
11859       --  Normal case, not a qualified expression
11860
11861       else
11862          return Expr;
11863       end if;
11864    end Unqualify;
11865
11866    -----------------------
11867    -- Visible_Ancestors --
11868    -----------------------
11869
11870    function Visible_Ancestors (Typ : Entity_Id) return Elist_Id is
11871       List_1 : Elist_Id;
11872       List_2 : Elist_Id;
11873       Elmt   : Elmt_Id;
11874
11875    begin
11876       pragma Assert (Is_Record_Type (Typ)
11877         and then Is_Tagged_Type (Typ));
11878
11879       --  Collect all the parents and progenitors of Typ. If the full-view of
11880       --  private parents and progenitors is available then it is used to
11881       --  generate the list of visible ancestors; otherwise their partial
11882       --  view is added to the resulting list.
11883
11884       Collect_Parents
11885         (T               => Typ,
11886          List            => List_1,
11887          Use_Full_View   => True);
11888
11889       Collect_Interfaces
11890         (T               => Typ,
11891          Ifaces_List     => List_2,
11892          Exclude_Parents => True,
11893          Use_Full_View   => True);
11894
11895       --  Join the two lists. Avoid duplications because an interface may
11896       --  simultaneously be parent and progenitor of a type.
11897
11898       Elmt := First_Elmt (List_2);
11899       while Present (Elmt) loop
11900          Append_Unique_Elmt (Node (Elmt), List_1);
11901          Next_Elmt (Elmt);
11902       end loop;
11903
11904       return List_1;
11905    end Visible_Ancestors;
11906
11907    ----------------------
11908    -- Within_Init_Proc --
11909    ----------------------
11910
11911    function Within_Init_Proc return Boolean is
11912       S : Entity_Id;
11913
11914    begin
11915       S := Current_Scope;
11916       while not Is_Overloadable (S) loop
11917          if S = Standard_Standard then
11918             return False;
11919          else
11920             S := Scope (S);
11921          end if;
11922       end loop;
11923
11924       return Is_Init_Proc (S);
11925    end Within_Init_Proc;
11926
11927    ----------------
11928    -- Wrong_Type --
11929    ----------------
11930
11931    procedure Wrong_Type (Expr : Node_Id; Expected_Type : Entity_Id) is
11932       Found_Type : constant Entity_Id := First_Subtype (Etype (Expr));
11933       Expec_Type : constant Entity_Id := First_Subtype (Expected_Type);
11934
11935       function Has_One_Matching_Field return Boolean;
11936       --  Determines if Expec_Type is a record type with a single component or
11937       --  discriminant whose type matches the found type or is one dimensional
11938       --  array whose component type matches the found type.
11939
11940       ----------------------------
11941       -- Has_One_Matching_Field --
11942       ----------------------------
11943
11944       function Has_One_Matching_Field return Boolean is
11945          E : Entity_Id;
11946
11947       begin
11948          if Is_Array_Type (Expec_Type)
11949            and then Number_Dimensions (Expec_Type) = 1
11950            and then
11951              Covers (Etype (Component_Type (Expec_Type)), Found_Type)
11952          then
11953             return True;
11954
11955          elsif not Is_Record_Type (Expec_Type) then
11956             return False;
11957
11958          else
11959             E := First_Entity (Expec_Type);
11960             loop
11961                if No (E) then
11962                   return False;
11963
11964                elsif (Ekind (E) /= E_Discriminant
11965                        and then Ekind (E) /= E_Component)
11966                  or else (Chars (E) = Name_uTag
11967                            or else Chars (E) = Name_uParent)
11968                then
11969                   Next_Entity (E);
11970
11971                else
11972                   exit;
11973                end if;
11974             end loop;
11975
11976             if not Covers (Etype (E), Found_Type) then
11977                return False;
11978
11979             elsif Present (Next_Entity (E)) then
11980                return False;
11981
11982             else
11983                return True;
11984             end if;
11985          end if;
11986       end Has_One_Matching_Field;
11987
11988    --  Start of processing for Wrong_Type
11989
11990    begin
11991       --  Don't output message if either type is Any_Type, or if a message
11992       --  has already been posted for this node. We need to do the latter
11993       --  check explicitly (it is ordinarily done in Errout), because we
11994       --  are using ! to force the output of the error messages.
11995
11996       if Expec_Type = Any_Type
11997         or else Found_Type = Any_Type
11998         or else Error_Posted (Expr)
11999       then
12000          return;
12001
12002       --  In  an instance, there is an ongoing problem with completion of
12003       --  type derived from private types. Their structure is what Gigi
12004       --  expects, but the  Etype is the parent type rather than the
12005       --  derived private type itself. Do not flag error in this case. The
12006       --  private completion is an entity without a parent, like an Itype.
12007       --  Similarly, full and partial views may be incorrect in the instance.
12008       --  There is no simple way to insure that it is consistent ???
12009
12010       elsif In_Instance then
12011          if Etype (Etype (Expr)) = Etype (Expected_Type)
12012            and then
12013              (Has_Private_Declaration (Expected_Type)
12014                or else Has_Private_Declaration (Etype (Expr)))
12015            and then No (Parent (Expected_Type))
12016          then
12017             return;
12018          end if;
12019       end if;
12020
12021       --  An interesting special check. If the expression is parenthesized
12022       --  and its type corresponds to the type of the sole component of the
12023       --  expected record type, or to the component type of the expected one
12024       --  dimensional array type, then assume we have a bad aggregate attempt.
12025
12026       if Nkind (Expr) in N_Subexpr
12027         and then Paren_Count (Expr) /= 0
12028         and then Has_One_Matching_Field
12029       then
12030          Error_Msg_N ("positional aggregate cannot have one component", Expr);
12031
12032       --  Another special check, if we are looking for a pool-specific access
12033       --  type and we found an E_Access_Attribute_Type, then we have the case
12034       --  of an Access attribute being used in a context which needs a pool-
12035       --  specific type, which is never allowed. The one extra check we make
12036       --  is that the expected designated type covers the Found_Type.
12037
12038       elsif Is_Access_Type (Expec_Type)
12039         and then Ekind (Found_Type) = E_Access_Attribute_Type
12040         and then Ekind (Base_Type (Expec_Type)) /= E_General_Access_Type
12041         and then Ekind (Base_Type (Expec_Type)) /= E_Anonymous_Access_Type
12042         and then Covers
12043           (Designated_Type (Expec_Type), Designated_Type (Found_Type))
12044       then
12045          Error_Msg_N -- CODEFIX
12046            ("result must be general access type!", Expr);
12047          Error_Msg_NE -- CODEFIX
12048            ("add ALL to }!", Expr, Expec_Type);
12049
12050       --  Another special check, if the expected type is an integer type,
12051       --  but the expression is of type System.Address, and the parent is
12052       --  an addition or subtraction operation whose left operand is the
12053       --  expression in question and whose right operand is of an integral
12054       --  type, then this is an attempt at address arithmetic, so give
12055       --  appropriate message.
12056
12057       elsif Is_Integer_Type (Expec_Type)
12058         and then Is_RTE (Found_Type, RE_Address)
12059         and then (Nkind (Parent (Expr)) = N_Op_Add
12060                     or else
12061                   Nkind (Parent (Expr)) = N_Op_Subtract)
12062         and then Expr = Left_Opnd (Parent (Expr))
12063         and then Is_Integer_Type (Etype (Right_Opnd (Parent (Expr))))
12064       then
12065          Error_Msg_N
12066            ("address arithmetic not predefined in package System",
12067             Parent (Expr));
12068          Error_Msg_N
12069            ("\possible missing with/use of System.Storage_Elements",
12070             Parent (Expr));
12071          return;
12072
12073       --  If the expected type is an anonymous access type, as for access
12074       --  parameters and discriminants, the error is on the designated types.
12075
12076       elsif Ekind (Expec_Type) = E_Anonymous_Access_Type then
12077          if Comes_From_Source (Expec_Type) then
12078             Error_Msg_NE ("expected}!", Expr, Expec_Type);
12079          else
12080             Error_Msg_NE
12081               ("expected an access type with designated}",
12082                  Expr, Designated_Type (Expec_Type));
12083          end if;
12084
12085          if Is_Access_Type (Found_Type)
12086            and then not Comes_From_Source (Found_Type)
12087          then
12088             Error_Msg_NE
12089               ("\\found an access type with designated}!",
12090                 Expr, Designated_Type (Found_Type));
12091          else
12092             if From_With_Type (Found_Type) then
12093                Error_Msg_NE ("\\found incomplete}!", Expr, Found_Type);
12094                Error_Msg_Qual_Level := 99;
12095                Error_Msg_NE -- CODEFIX
12096                  ("\\missing `WITH &;", Expr, Scope (Found_Type));
12097                Error_Msg_Qual_Level := 0;
12098             else
12099                Error_Msg_NE ("found}!", Expr, Found_Type);
12100             end if;
12101          end if;
12102
12103       --  Normal case of one type found, some other type expected
12104
12105       else
12106          --  If the names of the two types are the same, see if some number
12107          --  of levels of qualification will help. Don't try more than three
12108          --  levels, and if we get to standard, it's no use (and probably
12109          --  represents an error in the compiler) Also do not bother with
12110          --  internal scope names.
12111
12112          declare
12113             Expec_Scope : Entity_Id;
12114             Found_Scope : Entity_Id;
12115
12116          begin
12117             Expec_Scope := Expec_Type;
12118             Found_Scope := Found_Type;
12119
12120             for Levels in Int range 0 .. 3 loop
12121                if Chars (Expec_Scope) /= Chars (Found_Scope) then
12122                   Error_Msg_Qual_Level := Levels;
12123                   exit;
12124                end if;
12125
12126                Expec_Scope := Scope (Expec_Scope);
12127                Found_Scope := Scope (Found_Scope);
12128
12129                exit when Expec_Scope = Standard_Standard
12130                  or else Found_Scope = Standard_Standard
12131                  or else not Comes_From_Source (Expec_Scope)
12132                  or else not Comes_From_Source (Found_Scope);
12133             end loop;
12134          end;
12135
12136          if Is_Record_Type (Expec_Type)
12137            and then Present (Corresponding_Remote_Type (Expec_Type))
12138          then
12139             Error_Msg_NE ("expected}!", Expr,
12140                           Corresponding_Remote_Type (Expec_Type));
12141          else
12142             Error_Msg_NE ("expected}!", Expr, Expec_Type);
12143          end if;
12144
12145          if Is_Entity_Name (Expr)
12146            and then Is_Package_Or_Generic_Package (Entity (Expr))
12147          then
12148             Error_Msg_N ("\\found package name!", Expr);
12149
12150          elsif Is_Entity_Name (Expr)
12151            and then
12152              (Ekind (Entity (Expr)) = E_Procedure
12153                 or else
12154               Ekind (Entity (Expr)) = E_Generic_Procedure)
12155          then
12156             if Ekind (Expec_Type) = E_Access_Subprogram_Type then
12157                Error_Msg_N
12158                  ("found procedure name, possibly missing Access attribute!",
12159                    Expr);
12160             else
12161                Error_Msg_N
12162                  ("\\found procedure name instead of function!", Expr);
12163             end if;
12164
12165          elsif Nkind (Expr) = N_Function_Call
12166            and then Ekind (Expec_Type) = E_Access_Subprogram_Type
12167            and then Etype (Designated_Type (Expec_Type)) = Etype (Expr)
12168            and then No (Parameter_Associations (Expr))
12169          then
12170             Error_Msg_N
12171               ("found function name, possibly missing Access attribute!",
12172                Expr);
12173
12174          --  Catch common error: a prefix or infix operator which is not
12175          --  directly visible because the type isn't.
12176
12177          elsif Nkind (Expr) in N_Op
12178             and then Is_Overloaded (Expr)
12179             and then not Is_Immediately_Visible (Expec_Type)
12180             and then not Is_Potentially_Use_Visible (Expec_Type)
12181             and then not In_Use (Expec_Type)
12182             and then Has_Compatible_Type (Right_Opnd (Expr), Expec_Type)
12183          then
12184             Error_Msg_N
12185               ("operator of the type is not directly visible!", Expr);
12186
12187          elsif Ekind (Found_Type) = E_Void
12188            and then Present (Parent (Found_Type))
12189            and then Nkind (Parent (Found_Type)) = N_Full_Type_Declaration
12190          then
12191             Error_Msg_NE ("\\found premature usage of}!", Expr, Found_Type);
12192
12193          else
12194             Error_Msg_NE ("\\found}!", Expr, Found_Type);
12195          end if;
12196
12197          --  A special check for cases like M1 and M2 = 0 where M1 and M2 are
12198          --  of the same modular type, and (M1 and M2) = 0 was intended.
12199
12200          if Expec_Type = Standard_Boolean
12201            and then Is_Modular_Integer_Type (Found_Type)
12202            and then Nkind_In (Parent (Expr), N_Op_And, N_Op_Or, N_Op_Xor)
12203            and then Nkind (Right_Opnd (Parent (Expr))) in N_Op_Compare
12204          then
12205             declare
12206                Op : constant Node_Id := Right_Opnd (Parent (Expr));
12207                L  : constant Node_Id := Left_Opnd (Op);
12208                R  : constant Node_Id := Right_Opnd (Op);
12209             begin
12210                --  The case for the message is when the left operand of the
12211                --  comparison is the same modular type, or when it is an
12212                --  integer literal (or other universal integer expression),
12213                --  which would have been typed as the modular type if the
12214                --  parens had been there.
12215
12216                if (Etype (L) = Found_Type
12217                      or else
12218                    Etype (L) = Universal_Integer)
12219                  and then Is_Integer_Type (Etype (R))
12220                then
12221                   Error_Msg_N
12222                     ("\\possible missing parens for modular operation", Expr);
12223                end if;
12224             end;
12225          end if;
12226
12227          --  Reset error message qualification indication
12228
12229          Error_Msg_Qual_Level := 0;
12230       end if;
12231    end Wrong_Type;
12232
12233 end Sem_Util;