gcc/ada/lib-xref.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                             L I B . X R E F                              --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1998-2011, 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 Csets;    use Csets;
  28 with Elists;   use Elists;
  29 with Errout;   use Errout;
  30 with Nlists;   use Nlists;
  31 with Opt;      use Opt;
  32 with Restrict; use Restrict;
  33 with Rident;   use Rident;
  34 with Sem;      use Sem;
  35 with Sem_Aux;  use Sem_Aux;
  36 with Sem_Prag; use Sem_Prag;
  37 with Sem_Util; use Sem_Util;
  38 with Sem_Warn; use Sem_Warn;
  39 with Sinfo;    use Sinfo;
  40 with Sinput;   use Sinput;
  41 with Snames;   use Snames;
  42 with Stringt;  use Stringt;
  43 with Stand;    use Stand;
  44 with Table;    use Table;
  45
  46 with GNAT.Heap_Sort_G;
  47
  48 package body Lib.Xref is
  49
  50    ------------------
  51    -- Declarations --
  52    ------------------
  53
  54    --  The Xref table is used to record references. The Loc field is set
  55    --  to No_Location for a definition entry.
  56
  57    subtype Xref_Entry_Number is Int;
  58
  59    type Xref_Entry is record
  60       Ent : Entity_Id;
  61       --  Entity referenced (E parameter to Generate_Reference)
  62
  63       Def : Source_Ptr;
  64       --  Original source location for entity being referenced. Note that these
  65       --  values are used only during the output process, they are not set when
  66       --  the entries are originally built. This is because private entities
  67       --  can be swapped when the initial call is made.
  68
  69       Loc : Source_Ptr;
  70       --  Location of reference (Original_Location (Sloc field of N parameter
  71       --  to Generate_Reference). Set to No_Location for the case of a
  72       --  defining occurrence.
  73
  74       Typ : Character;
  75       --  Reference type (Typ param to Generate_Reference)
  76
  77       Eun : Unit_Number_Type;
  78       --  Unit number corresponding to Ent
  79
  80       Lun : Unit_Number_Type;
  81       --  Unit number corresponding to Loc. Value is undefined and not
  82       --  referenced if Loc is set to No_Location.
  83
  84       --  The following components are only used for ALFA cross-references
  85
  86       Ref_Scope : Entity_Id;
  87       --  Entity of the closest subprogram or package enclosing the reference
  88
  89       Ent_Scope : Entity_Id;
  90       --  Entity of the closest subprogram or package enclosing the definition,
  91       --  which should be located in the same file as the definition itself.
  92
  93       Ent_Scope_File : Unit_Number_Type;
  94       --  File for entity Ent_Scope
  95    end record;
  96
  97    package Xrefs is new Table.Table (
  98      Table_Component_Type => Xref_Entry,
  99      Table_Index_Type     => Xref_Entry_Number,
 100      Table_Low_Bound      => 1,
 101      Table_Initial        => Alloc.Xrefs_Initial,
 102      Table_Increment      => Alloc.Xrefs_Increment,
 103      Table_Name           => "Xrefs");
 104
 105    ----------------------
 106    -- ALFA Information --
 107    ----------------------
 108
 109    package body ALFA is separate;
 110
 111    ------------------------
 112    --  Local Subprograms --
 113    ------------------------
 114
 115    function Enclosing_Subprogram_Or_Package (N : Node_Id) return Entity_Id;
 116    --  Return the closest enclosing subprogram of package
 117
 118    procedure Generate_Prim_Op_References (Typ : Entity_Id);
 119    --  For a tagged type, generate implicit references to its primitive
 120    --  operations, for source navigation. This is done right before emitting
 121    --  cross-reference information rather than at the freeze point of the type
 122    --  in order to handle late bodies that are primitive operations.
 123
 124    function Lt (T1, T2 : Xref_Entry) return Boolean;
 125    --  Order cross-references
 126
 127    -------------------------------------
 128    -- Enclosing_Subprogram_Or_Package --
 129    -------------------------------------
 130
 131    function Enclosing_Subprogram_Or_Package (N : Node_Id) return Entity_Id is
 132       Result         : Entity_Id;
 133
 134    begin
 135       --  If N is the defining identifier for a subprogram, then return the
 136       --  enclosing subprogram or package, not this subprogram.
 137
 138       if Nkind_In (N, N_Defining_Identifier, N_Defining_Operator_Symbol)
 139         and then Nkind (Parent (N)) in N_Subprogram_Specification
 140       then
 141          Result := Parent (Parent (Parent (N)));
 142       else
 143          Result := N;
 144       end if;
 145
 146       loop
 147          exit when No (Result);
 148
 149          case Nkind (Result) is
 150             when N_Package_Specification =>
 151                Result := Defining_Unit_Name (Result);
 152                exit;
 153
 154             when N_Package_Body =>
 155                Result := Defining_Unit_Name (Result);
 156                exit;
 157
 158             when N_Subprogram_Specification =>
 159                Result := Defining_Unit_Name (Result);
 160                exit;
 161
 162             when N_Subprogram_Declaration =>
 163                Result := Defining_Unit_Name (Specification (Result));
 164                exit;
 165
 166             when N_Subprogram_Body =>
 167                Result := Defining_Unit_Name (Specification (Result));
 168                exit;
 169
 170             when others =>
 171                Result := Parent (Result);
 172          end case;
 173       end loop;
 174
 175       if Nkind (Result) = N_Defining_Program_Unit_Name then
 176          Result := Defining_Identifier (Result);
 177       end if;
 178
 179       --  Do no return a scope without a proper location
 180
 181       if Present (Result)
 182         and then Sloc (Result) = No_Location
 183       then
 184          return Empty;
 185       end if;
 186
 187       return Result;
 188    end Enclosing_Subprogram_Or_Package;
 189
 190    -------------------------
 191    -- Generate_Definition --
 192    -------------------------
 193
 194    procedure Generate_Definition (E : Entity_Id) is
 195       Loc  : Source_Ptr;
 196       Indx : Nat;
 197
 198    begin
 199       pragma Assert (Nkind (E) in N_Entity);
 200
 201       --  Note that we do not test Xref_Entity_Letters here. It is too early
 202       --  to do so, since we are often called before the entity is fully
 203       --  constructed, so that the Ekind is still E_Void.
 204
 205       if Opt.Xref_Active
 206
 207          --  Definition must come from source
 208
 209          --  We make an exception for subprogram child units that have no spec.
 210          --  For these we generate a subprogram declaration for library use,
 211          --  and the corresponding entity does not come from source.
 212          --  Nevertheless, all references will be attached to it and we have
 213          --  to treat is as coming from user code.
 214
 215          and then (Comes_From_Source (E) or else Is_Child_Unit (E))
 216
 217          --  And must have a reasonable source location that is not
 218          --  within an instance (all entities in instances are ignored)
 219
 220          and then Sloc (E) > No_Location
 221          and then Instantiation_Location (Sloc (E)) = No_Location
 222
 223          --  And must be a non-internal name from the main source unit
 224
 225          and then In_Extended_Main_Source_Unit (E)
 226          and then not Is_Internal_Name (Chars (E))
 227       then
 228          Xrefs.Increment_Last;
 229          Indx := Xrefs.Last;
 230          Loc  := Original_Location (Sloc (E));
 231
 232          Xrefs.Table (Indx).Ent := E;
 233          Xrefs.Table (Indx).Typ := ' ';
 234          Xrefs.Table (Indx).Def := No_Location;
 235          Xrefs.Table (Indx).Loc := No_Location;
 236
 237          Xrefs.Table (Indx).Eun := Get_Source_Unit (Loc);
 238
 239          Xrefs.Table (Indx).Ref_Scope      := Empty;
 240          Xrefs.Table (Indx).Ent_Scope      := Empty;
 241          Xrefs.Table (Indx).Ent_Scope_File := No_Unit;
 242
 243          Set_Has_Xref_Entry (E);
 244
 245          if In_Inlined_Body then
 246             Set_Referenced (E);
 247          end if;
 248       end if;
 249    end Generate_Definition;
 250
 251    ---------------------------------
 252    -- Generate_Operator_Reference --
 253    ---------------------------------
 254
 255    procedure Generate_Operator_Reference
 256      (N : Node_Id;
 257       T : Entity_Id)
 258    is
 259    begin
 260       if not In_Extended_Main_Source_Unit (N) then
 261          return;
 262       end if;
 263
 264       --  If the operator is not a Standard operator, then we generate a real
 265       --  reference to the user defined operator.
 266
 267       if Sloc (Entity (N)) /= Standard_Location then
 268          Generate_Reference (Entity (N), N);
 269
 270          --  A reference to an implicit inequality operator is also a reference
 271          --  to the user-defined equality.
 272
 273          if Nkind (N) = N_Op_Ne
 274            and then not Comes_From_Source (Entity (N))
 275            and then Present (Corresponding_Equality (Entity (N)))
 276          then
 277             Generate_Reference (Corresponding_Equality (Entity (N)), N);
 278          end if;
 279
 280       --  For the case of Standard operators, we mark the result type as
 281       --  referenced. This ensures that in the case where we are using a
 282       --  derived operator, we mark an entity of the unit that implicitly
 283       --  defines this operator as used. Otherwise we may think that no entity
 284       --  of the unit is used. The actual entity marked as referenced is the
 285       --  first subtype, which is the relevant user defined entity.
 286
 287       --  Note: we only do this for operators that come from source. The
 288       --  generated code sometimes reaches for entities that do not need to be
 289       --  explicitly visible (for example, when we expand the code for
 290       --  comparing two record objects, the fields of the record may not be
 291       --  visible).
 292
 293       elsif Comes_From_Source (N) then
 294          Set_Referenced (First_Subtype (T));
 295       end if;
 296    end Generate_Operator_Reference;
 297
 298    ---------------------------------
 299    -- Generate_Prim_Op_References --
 300    ---------------------------------
 301
 302    procedure Generate_Prim_Op_References (Typ : Entity_Id) is
 303       Base_T    : Entity_Id;
 304       Prim      : Elmt_Id;
 305       Prim_List : Elist_Id;
 306
 307    begin
 308       --  Handle subtypes of synchronized types
 309
 310       if Ekind (Typ) = E_Protected_Subtype
 311         or else Ekind (Typ) = E_Task_Subtype
 312       then
 313          Base_T := Etype (Typ);
 314       else
 315          Base_T := Typ;
 316       end if;
 317
 318       --  References to primitive operations are only relevant for tagged types
 319
 320       if not Is_Tagged_Type (Base_T)
 321         or else Is_Class_Wide_Type (Base_T)
 322       then
 323          return;
 324       end if;
 325
 326       --  Ada 2005 (AI-345): For synchronized types generate reference to the
 327       --  wrapper that allow us to dispatch calls through their implemented
 328       --  abstract interface types.
 329
 330       --  The check for Present here is to protect against previously reported
 331       --  critical errors.
 332
 333       Prim_List := Primitive_Operations (Base_T);
 334
 335       if No (Prim_List) then
 336          return;
 337       end if;
 338
 339       Prim := First_Elmt (Prim_List);
 340       while Present (Prim) loop
 341
 342          --  If the operation is derived, get the original for cross-reference
 343          --  reference purposes (it is the original for which we want the xref
 344          --  and for which the comes_from_source test must be performed).
 345
 346          Generate_Reference
 347            (Typ, Ultimate_Alias (Node (Prim)), 'p', Set_Ref => False);
 348          Next_Elmt (Prim);
 349       end loop;
 350    end Generate_Prim_Op_References;
 351
 352    ------------------------
 353    -- Generate_Reference --
 354    ------------------------
 355
 356    procedure Generate_Reference
 357      (E       : Entity_Id;
 358       N       : Node_Id;
 359       Typ     : Character := 'r';
 360       Set_Ref : Boolean   := True;
 361       Force   : Boolean   := False)
 362    is
 363       Indx : Nat;
 364       Nod  : Node_Id;
 365       Ref  : Source_Ptr;
 366       Def  : Source_Ptr;
 367       Ent  : Entity_Id;
 368
 369       Ref_Scope     : Entity_Id;
 370       Ent_Scope     : Entity_Id;
 371
 372       Call   : Node_Id;
 373       Formal : Entity_Id;
 374       --  Used for call to Find_Actual
 375
 376       Kind : Entity_Kind;
 377       --  If Formal is non-Empty, then its Ekind, otherwise E_Void
 378
 379       function Is_On_LHS (Node : Node_Id) return Boolean;
 380       --  Used to check if a node is on the left hand side of an assignment.
 381       --  The following cases are handled:
 382       --
 383       --   Variable    Node is a direct descendant of left hand side of an
 384       --               assignment statement.
 385       --
 386       --   Prefix      Of an indexed or selected component that is present in
 387       --               a subtree rooted by an assignment statement. There is
 388       --               no restriction of nesting of components, thus cases
 389       --               such as A.B (C).D are handled properly. However a prefix
 390       --               of a dereference (either implicit or explicit) is never
 391       --               considered as on a LHS.
 392       --
 393       --   Out param   Same as above cases, but OUT parameter
 394
 395       function OK_To_Set_Referenced return Boolean;
 396       --  Returns True if the Referenced flag can be set. There are a few
 397       --  exceptions where we do not want to set this flag, see body for
 398       --  details of these exceptional cases.
 399
 400       ---------------
 401       -- Is_On_LHS --
 402       ---------------
 403
 404       --  ??? There are several routines here and there that perform a similar
 405       --      (but subtly different) computation, which should be factored:
 406
 407       --      Sem_Util.May_Be_Lvalue
 408       --      Sem_Util.Known_To_Be_Assigned
 409       --      Exp_Ch2.Expand_Entry_Parameter.In_Assignment_Context
 410       --      Exp_Smem.Is_Out_Actual
 411
 412       function Is_On_LHS (Node : Node_Id) return Boolean is
 413          N : Node_Id;
 414          P : Node_Id;
 415          K : Node_Kind;
 416
 417       begin
 418          --  Only identifiers are considered, is this necessary???
 419
 420          if Nkind (Node) /= N_Identifier then
 421             return False;
 422          end if;
 423
 424          --  Immediate return if appeared as OUT parameter
 425
 426          if Kind = E_Out_Parameter then
 427             return True;
 428          end if;
 429
 430          --  Search for assignment statement subtree root
 431
 432          N := Node;
 433          loop
 434             P := Parent (N);
 435             K := Nkind (P);
 436
 437             if K = N_Assignment_Statement then
 438                return Name (P) = N;
 439
 440             --  Check whether the parent is a component and the current node is
 441             --  its prefix, but return False if the current node has an access
 442             --  type, as in that case the selected or indexed component is an
 443             --  implicit dereference, and the LHS is the designated object, not
 444             --  the access object.
 445
 446             --  ??? case of a slice assignment?
 447
 448             --  ??? Note that in some cases this is called too early
 449             --  (see comments in Sem_Ch8.Find_Direct_Name), at a point where
 450             --  the tree is not fully typed yet. In that case we may lack
 451             --  an Etype for N, and we must disable the check for an implicit
 452             --  dereference. If the dereference is on an LHS, this causes a
 453             --  false positive.
 454
 455             elsif (K = N_Selected_Component or else K = N_Indexed_Component)
 456               and then Prefix (P) = N
 457               and then not (Present (Etype (N))
 458                               and then
 459                             Is_Access_Type (Etype (N)))
 460             then
 461                N := P;
 462
 463             --  All other cases, definitely not on left side
 464
 465             else
 466                return False;
 467             end if;
 468          end loop;
 469       end Is_On_LHS;
 470
 471       ---------------------------
 472       -- OK_To_Set_Referenced --
 473       ---------------------------
 474
 475       function OK_To_Set_Referenced return Boolean is
 476          P : Node_Id;
 477
 478       begin
 479          --  A reference from a pragma Unreferenced or pragma Unmodified or
 480          --  pragma Warnings does not cause the Referenced flag to be set.
 481          --  This avoids silly warnings about things being referenced and
 482          --  not assigned when the only reference is from the pragma.
 483
 484          if Nkind (N) = N_Identifier then
 485             P := Parent (N);
 486
 487             if Nkind (P) = N_Pragma_Argument_Association then
 488                P := Parent (P);
 489
 490                if Nkind (P) = N_Pragma then
 491                   if Pragma_Name (P) = Name_Warnings
 492                        or else
 493                      Pragma_Name (P) = Name_Unmodified
 494                        or else
 495                      Pragma_Name (P) = Name_Unreferenced
 496                   then
 497                      return False;
 498                   end if;
 499                end if;
 500             end if;
 501          end if;
 502
 503          return True;
 504       end OK_To_Set_Referenced;
 505
 506    --  Start of processing for Generate_Reference
 507
 508    begin
 509       pragma Assert (Nkind (E) in N_Entity);
 510       Find_Actual (N, Formal, Call);
 511
 512       if Present (Formal) then
 513          Kind := Ekind (Formal);
 514       else
 515          Kind := E_Void;
 516       end if;
 517
 518       --  Check for obsolescent reference to package ASCII. GNAT treats this
 519       --  element of annex J specially since in practice, programs make a lot
 520       --  of use of this feature, so we don't include it in the set of features
 521       --  diagnosed when Warn_On_Obsolescent_Features mode is set. However we
 522       --  are required to note it as a violation of the RM defined restriction.
 523
 524       if E = Standard_ASCII then
 525          Check_Restriction (No_Obsolescent_Features, N);
 526       end if;
 527
 528       --  Check for reference to entity marked with Is_Obsolescent
 529
 530       --  Note that we always allow obsolescent references in the compiler
 531       --  itself and the run time, since we assume that we know what we are
 532       --  doing in such cases. For example the calls in Ada.Characters.Handling
 533       --  to its own obsolescent subprograms are just fine.
 534
 535       --  In any case we do not generate warnings within the extended source
 536       --  unit of the entity in question, since we assume the source unit
 537       --  itself knows what is going on (and for sure we do not want silly
 538       --  warnings, e.g. on the end line of an obsolescent procedure body).
 539
 540       if Is_Obsolescent (E)
 541         and then not GNAT_Mode
 542         and then not In_Extended_Main_Source_Unit (E)
 543       then
 544          Check_Restriction (No_Obsolescent_Features, N);
 545
 546          if Warn_On_Obsolescent_Feature then
 547             Output_Obsolescent_Entity_Warnings (N, E);
 548          end if;
 549       end if;
 550
 551       --  Warn if reference to Ada 2005 entity not in Ada 2005 mode. We only
 552       --  detect real explicit references (modifications and references).
 553
 554       if Comes_From_Source (N)
 555         and then Is_Ada_2005_Only (E)
 556         and then Ada_Version < Ada_2005
 557         and then Warn_On_Ada_2005_Compatibility
 558         and then (Typ = 'm' or else Typ = 'r' or else Typ = 's')
 559       then
 560          Error_Msg_NE ("& is only defined in Ada 2005?", N, E);
 561       end if;
 562
 563       --  Warn if reference to Ada 2012 entity not in Ada 2012 mode. We only
 564       --  detect real explicit references (modifications and references).
 565
 566       if Comes_From_Source (N)
 567         and then Is_Ada_2012_Only (E)
 568         and then Ada_Version < Ada_2012
 569         and then Warn_On_Ada_2012_Compatibility
 570         and then (Typ = 'm' or else Typ = 'r')
 571       then
 572          Error_Msg_NE ("& is only defined in Ada 2012?", N, E);
 573       end if;
 574
 575       --  Never collect references if not in main source unit. However, we omit
 576       --  this test if Typ is 'e' or 'k', since these entries are structural,
 577       --  and it is useful to have them in units that reference packages as
 578       --  well as units that define packages. We also omit the test for the
 579       --  case of 'p' since we want to include inherited primitive operations
 580       --  from other packages.
 581
 582       --  We also omit this test is this is a body reference for a subprogram
 583       --  instantiation. In this case the reference is to the generic body,
 584       --  which clearly need not be in the main unit containing the instance.
 585       --  For the same reason we accept an implicit reference generated for
 586       --  a default in an instance.
 587
 588       if not In_Extended_Main_Source_Unit (N) then
 589          if Typ = 'e'
 590            or else Typ = 'I'
 591            or else Typ = 'p'
 592            or else Typ = 'i'
 593            or else Typ = 'k'
 594            or else (Typ = 'b' and then Is_Generic_Instance (E))
 595          then
 596             null;
 597          else
 598             return;
 599          end if;
 600       end if;
 601
 602       --  For reference type p, the entity must be in main source unit
 603
 604       if Typ = 'p' and then not In_Extended_Main_Source_Unit (E) then
 605          return;
 606       end if;
 607
 608       --  Unless the reference is forced, we ignore references where the
 609       --  reference itself does not come from source.
 610
 611       if not Force and then not Comes_From_Source (N) then
 612          return;
 613       end if;
 614
 615       --  Deal with setting entity as referenced, unless suppressed. Note that
 616       --  we still do Set_Referenced on entities that do not come from source.
 617       --  This situation arises when we have a source reference to a derived
 618       --  operation, where the derived operation itself does not come from
 619       --  source, but we still want to mark it as referenced, since we really
 620       --  are referencing an entity in the corresponding package (this avoids
 621       --  wrong complaints that the package contains no referenced entities).
 622
 623       if Set_Ref then
 624
 625          --  Assignable object appearing on left side of assignment or as
 626          --  an out parameter.
 627
 628          if Is_Assignable (E)
 629            and then Is_On_LHS (N)
 630            and then Ekind (E) /= E_In_Out_Parameter
 631          then
 632             --  For objects that are renamings, just set as simply referenced
 633             --  we do not try to do assignment type tracking in this case.
 634
 635             if Present (Renamed_Object (E)) then
 636                Set_Referenced (E);
 637
 638             --  Out parameter case
 639
 640             elsif Kind = E_Out_Parameter then
 641
 642                --  If warning mode for all out parameters is set, or this is
 643                --  the only warning parameter, then we want to mark this for
 644                --  later warning logic by setting Referenced_As_Out_Parameter
 645
 646                if Warn_On_Modified_As_Out_Parameter (Formal) then
 647                   Set_Referenced_As_Out_Parameter (E, True);
 648                   Set_Referenced_As_LHS (E, False);
 649
 650                --  For OUT parameter not covered by the above cases, we simply
 651                --  regard it as a normal reference (in this case we do not
 652                --  want any of the warning machinery for out parameters).
 653
 654                else
 655                   Set_Referenced (E);
 656                end if;
 657
 658             --  For the left hand of an assignment case, we do nothing here.
 659             --  The processing for Analyze_Assignment_Statement will set the
 660             --  Referenced_As_LHS flag.
 661
 662             else
 663                null;
 664             end if;
 665
 666          --  Check for a reference in a pragma that should not count as a
 667          --  making the variable referenced for warning purposes.
 668
 669          elsif Is_Non_Significant_Pragma_Reference (N) then
 670             null;
 671
 672          --  A reference in an attribute definition clause does not count as a
 673          --  reference except for the case of Address. The reason that 'Address
 674          --  is an exception is that it creates an alias through which the
 675          --  variable may be referenced.
 676
 677          elsif Nkind (Parent (N)) = N_Attribute_Definition_Clause
 678            and then Chars (Parent (N)) /= Name_Address
 679            and then N = Name (Parent (N))
 680          then
 681             null;
 682
 683          --  Constant completion does not count as a reference
 684
 685          elsif Typ = 'c'
 686            and then Ekind (E) = E_Constant
 687          then
 688             null;
 689
 690          --  Record representation clause does not count as a reference
 691
 692          elsif Nkind (N) = N_Identifier
 693            and then Nkind (Parent (N)) = N_Record_Representation_Clause
 694          then
 695             null;
 696
 697          --  Discriminants do not need to produce a reference to record type
 698
 699          elsif Typ = 'd'
 700            and then Nkind (Parent (N)) = N_Discriminant_Specification
 701          then
 702             null;
 703
 704          --  All other cases
 705
 706          else
 707             --  Special processing for IN OUT parameters, where we have an
 708             --  implicit assignment to a simple variable.
 709
 710             if Kind = E_In_Out_Parameter
 711               and then Is_Assignable (E)
 712             then
 713                --  For sure this counts as a normal read reference
 714
 715                Set_Referenced (E);
 716                Set_Last_Assignment (E, Empty);
 717
 718                --  We count it as being referenced as an out parameter if the
 719                --  option is set to warn on all out parameters, except that we
 720                --  have a special exclusion for an intrinsic subprogram, which
 721                --  is most likely an instantiation of Unchecked_Deallocation
 722                --  which we do not want to consider as an assignment since it
 723                --  generates false positives. We also exclude the case of an
 724                --  IN OUT parameter if the name of the procedure is Free,
 725                --  since we suspect similar semantics.
 726
 727                if Warn_On_All_Unread_Out_Parameters
 728                  and then Is_Entity_Name (Name (Call))
 729                  and then not Is_Intrinsic_Subprogram (Entity (Name (Call)))
 730                  and then Chars (Name (Call)) /= Name_Free
 731                then
 732                   Set_Referenced_As_Out_Parameter (E, True);
 733                   Set_Referenced_As_LHS (E, False);
 734                end if;
 735
 736             --  Don't count a recursive reference within a subprogram as a
 737             --  reference (that allows detection of a recursive subprogram
 738             --  whose only references are recursive calls as unreferenced).
 739
 740             elsif Is_Subprogram (E)
 741               and then E = Nearest_Dynamic_Scope (Current_Scope)
 742             then
 743                null;
 744
 745             --  Any other occurrence counts as referencing the entity
 746
 747             elsif OK_To_Set_Referenced then
 748                Set_Referenced (E);
 749
 750                --  If variable, this is an OK reference after an assignment
 751                --  so we can clear the Last_Assignment indication.
 752
 753                if Is_Assignable (E) then
 754                   Set_Last_Assignment (E, Empty);
 755                end if;
 756             end if;
 757          end if;
 758
 759          --  Check for pragma Unreferenced given and reference is within
 760          --  this source unit (occasion for possible warning to be issued).
 761
 762          if Has_Unreferenced (E)
 763            and then In_Same_Extended_Unit (E, N)
 764          then
 765             --  A reference as a named parameter in a call does not count
 766             --  as a violation of pragma Unreferenced for this purpose...
 767
 768             if Nkind (N) = N_Identifier
 769               and then Nkind (Parent (N)) = N_Parameter_Association
 770               and then Selector_Name (Parent (N)) = N
 771             then
 772                null;
 773
 774             --  ... Neither does a reference to a variable on the left side
 775             --  of an assignment.
 776
 777             elsif Is_On_LHS (N) then
 778                null;
 779
 780             --  For entry formals, we want to place the warning message on the
 781             --  corresponding entity in the accept statement. The current scope
 782             --  is the body of the accept, so we find the formal whose name
 783             --  matches that of the entry formal (there is no link between the
 784             --  two entities, and the one in the accept statement is only used
 785             --  for conformance checking).
 786
 787             elsif Ekind (Scope (E)) = E_Entry then
 788                declare
 789                   BE : Entity_Id;
 790
 791                begin
 792                   BE := First_Entity (Current_Scope);
 793                   while Present (BE) loop
 794                      if Chars (BE) = Chars (E) then
 795                         Error_Msg_NE -- CODEFIX
 796                           ("?pragma Unreferenced given for&!", N, BE);
 797                         exit;
 798                      end if;
 799
 800                      Next_Entity (BE);
 801                   end loop;
 802                end;
 803
 804             --  Here we issue the warning, since this is a real reference
 805
 806             else
 807                Error_Msg_NE -- CODEFIX
 808                  ("?pragma Unreferenced given for&!", N, E);
 809             end if;
 810          end if;
 811
 812          --  If this is a subprogram instance, mark as well the internal
 813          --  subprogram in the wrapper package, which may be a visible
 814          --  compilation unit.
 815
 816          if Is_Overloadable (E)
 817            and then Is_Generic_Instance (E)
 818            and then Present (Alias (E))
 819          then
 820             Set_Referenced (Alias (E));
 821          end if;
 822       end if;
 823
 824       --  Generate reference if all conditions are met:
 825
 826       if
 827          --  Cross referencing must be active
 828
 829          Opt.Xref_Active
 830
 831          --  The entity must be one for which we collect references
 832
 833          and then Xref_Entity_Letters (Ekind (E)) /= ' '
 834
 835          --  Both Sloc values must be set to something sensible
 836
 837          and then Sloc (E) > No_Location
 838          and then Sloc (N) > No_Location
 839
 840          --  We ignore references from within an instance, except for default
 841          --  subprograms, for which we generate an implicit reference.
 842
 843          and then
 844            (Instantiation_Location (Sloc (N)) = No_Location or else Typ = 'i')
 845
 846          --  Ignore dummy references
 847
 848         and then Typ /= ' '
 849       then
 850          if Nkind (N) = N_Identifier
 851               or else
 852             Nkind (N) = N_Defining_Identifier
 853               or else
 854             Nkind (N) in N_Op
 855               or else
 856             Nkind (N) = N_Defining_Operator_Symbol
 857               or else
 858             Nkind (N) = N_Operator_Symbol
 859               or else
 860             (Nkind (N) = N_Character_Literal
 861               and then Sloc (Entity (N)) /= Standard_Location)
 862               or else
 863             Nkind (N) = N_Defining_Character_Literal
 864          then
 865             Nod := N;
 866
 867          elsif Nkind (N) = N_Expanded_Name
 868                  or else
 869                Nkind (N) = N_Selected_Component
 870          then
 871             Nod := Selector_Name (N);
 872
 873          else
 874             return;
 875          end if;
 876
 877          --  Normal case of source entity comes from source
 878
 879          if Comes_From_Source (E) then
 880             Ent := E;
 881
 882          --  Entity does not come from source, but is a derived subprogram and
 883          --  the derived subprogram comes from source (after one or more
 884          --  derivations) in which case the reference is to parent subprogram.
 885
 886          elsif Is_Overloadable (E)
 887            and then Present (Alias (E))
 888          then
 889             Ent := Alias (E);
 890             while not Comes_From_Source (Ent) loop
 891                if No (Alias (Ent)) then
 892                   return;
 893                end if;
 894
 895                Ent := Alias (Ent);
 896             end loop;
 897
 898          --  The internally created defining entity for a child subprogram
 899          --  that has no previous spec has valid references.
 900
 901          elsif Is_Overloadable (E)
 902            and then Is_Child_Unit (E)
 903          then
 904             Ent := E;
 905
 906          --  Record components of discriminated subtypes or derived types must
 907          --  be treated as references to the original component.
 908
 909          elsif Ekind (E) = E_Component
 910            and then Comes_From_Source (Original_Record_Component (E))
 911          then
 912             Ent := Original_Record_Component (E);
 913
 914          --  If this is an expanded reference to a discriminant, recover the
 915          --  original discriminant, which gets the reference.
 916
 917          elsif Ekind (E) = E_In_Parameter
 918            and then  Present (Discriminal_Link (E))
 919          then
 920             Ent := Discriminal_Link (E);
 921             Set_Referenced (Ent);
 922
 923          --  Ignore reference to any other entity that is not from source
 924
 925          else
 926             return;
 927          end if;
 928
 929          --  Record reference to entity
 930
 931          Ref := Original_Location (Sloc (Nod));
 932          Def := Original_Location (Sloc (Ent));
 933
 934          Ref_Scope := Enclosing_Subprogram_Or_Package (N);
 935          Ent_Scope := Enclosing_Subprogram_Or_Package (Ent);
 936
 937          Xrefs.Increment_Last;
 938          Indx := Xrefs.Last;
 939
 940          Xrefs.Table (Indx).Loc := Ref;
 941
 942          --  Overriding operations are marked with 'P'
 943
 944          if Typ = 'p'
 945            and then Is_Subprogram (N)
 946            and then Present (Overridden_Operation (N))
 947          then
 948             Xrefs.Table (Indx).Typ := 'P';
 949          else
 950             Xrefs.Table (Indx).Typ := Typ;
 951          end if;
 952
 953          Xrefs.Table (Indx).Eun := Get_Source_Unit (Def);
 954          Xrefs.Table (Indx).Lun := Get_Source_Unit (Ref);
 955          Xrefs.Table (Indx).Ent := Ent;
 956
 957          Xrefs.Table (Indx).Ref_Scope      := Ref_Scope;
 958          Xrefs.Table (Indx).Ent_Scope      := Ent_Scope;
 959          Xrefs.Table (Indx).Ent_Scope_File := Get_Source_Unit (Ent_Scope);
 960
 961          Set_Has_Xref_Entry (Ent);
 962       end if;
 963    end Generate_Reference;
 964
 965    -----------------------------------
 966    -- Generate_Reference_To_Formals --
 967    -----------------------------------
 968
 969    procedure Generate_Reference_To_Formals (E : Entity_Id) is
 970       Formal : Entity_Id;
 971
 972    begin
 973       if Is_Generic_Subprogram (E) then
 974          Formal := First_Entity (E);
 975
 976          while Present (Formal)
 977            and then not Is_Formal (Formal)
 978          loop
 979             Next_Entity (Formal);
 980          end loop;
 981
 982       else
 983          Formal := First_Formal (E);
 984       end if;
 985
 986       while Present (Formal) loop
 987          if Ekind (Formal) = E_In_Parameter then
 988
 989             if Nkind (Parameter_Type (Parent (Formal)))
 990               = N_Access_Definition
 991             then
 992                Generate_Reference (E, Formal, '^', False);
 993             else
 994                Generate_Reference (E, Formal, '>', False);
 995             end if;
 996
 997          elsif Ekind (Formal) = E_In_Out_Parameter then
 998             Generate_Reference (E, Formal, '=', False);
 999
1000          else
1001             Generate_Reference (E, Formal, '<', False);
1002          end if;
1003
1004          Next_Formal (Formal);
1005       end loop;
1006    end Generate_Reference_To_Formals;
1007
1008    -------------------------------------------
1009    -- Generate_Reference_To_Generic_Formals --
1010    -------------------------------------------
1011
1012    procedure Generate_Reference_To_Generic_Formals (E : Entity_Id) is
1013       Formal : Entity_Id;
1014
1015    begin
1016       Formal := First_Entity (E);
1017       while Present (Formal) loop
1018          if Comes_From_Source (Formal) then
1019             Generate_Reference (E, Formal, 'z', False);
1020          end if;
1021
1022          Next_Entity (Formal);
1023       end loop;
1024    end Generate_Reference_To_Generic_Formals;
1025
1026    ----------------
1027    -- Initialize --
1028    ----------------
1029
1030    procedure Initialize is
1031    begin
1032       Xrefs.Init;
1033    end Initialize;
1034
1035    --------
1036    -- Lt --
1037    --------
1038
1039    function Lt (T1, T2 : Xref_Entry) return Boolean is
1040    begin
1041       --  First test: if entity is in different unit, sort by unit
1042
1043       if T1.Eun /= T2.Eun then
1044          return Dependency_Num (T1.Eun) < Dependency_Num (T2.Eun);
1045
1046       --  Second test: within same unit, sort by entity Sloc
1047
1048       elsif T1.Def /= T2.Def then
1049          return T1.Def < T2.Def;
1050
1051       --  Third test: sort definitions ahead of references
1052
1053       elsif T1.Loc = No_Location then
1054          return True;
1055
1056       elsif T2.Loc = No_Location then
1057          return False;
1058
1059       --  Fourth test: for same entity, sort by reference location unit
1060
1061       elsif T1.Lun /= T2.Lun then
1062          return Dependency_Num (T1.Lun) < Dependency_Num (T2.Lun);
1063
1064       --  Fifth test: order of location within referencing unit
1065
1066       elsif T1.Loc /= T2.Loc then
1067          return T1.Loc < T2.Loc;
1068
1069       --  Finally, for two locations at the same address, we prefer
1070       --  the one that does NOT have the type 'r' so that a modification
1071       --  or extension takes preference, when there are more than one
1072       --  reference at the same location. As a result, in the case of
1073       --  entities that are in-out actuals, the read reference follows
1074       --  the modify reference.
1075
1076       else
1077          return T2.Typ = 'r';
1078       end if;
1079    end Lt;
1080
1081    -----------------------
1082    -- Output_References --
1083    -----------------------
1084
1085    procedure Output_References is
1086
1087       procedure Get_Type_Reference
1088         (Ent   : Entity_Id;
1089          Tref  : out Entity_Id;
1090          Left  : out Character;
1091          Right : out Character);
1092       --  Given an Entity_Id Ent, determines whether a type reference is
1093       --  required. If so, Tref is set to the entity for the type reference
1094       --  and Left and Right are set to the left/right brackets to be output
1095       --  for the reference. If no type reference is required, then Tref is
1096       --  set to Empty, and Left/Right are set to space.
1097
1098       procedure Output_Import_Export_Info (Ent : Entity_Id);
1099       --  Output language and external name information for an interfaced
1100       --  entity, using the format <language, external_name>,
1101
1102       ------------------------
1103       -- Get_Type_Reference --
1104       ------------------------
1105
1106       procedure Get_Type_Reference
1107         (Ent   : Entity_Id;
1108          Tref  : out Entity_Id;
1109          Left  : out Character;
1110          Right : out Character)
1111       is
1112          Sav : Entity_Id;
1113
1114       begin
1115          --  See if we have a type reference
1116
1117          Tref := Ent;
1118          Left := '{';
1119          Right := '}';
1120
1121          loop
1122             Sav := Tref;
1123
1124             --  Processing for types
1125
1126             if Is_Type (Tref) then
1127
1128                --  Case of base type
1129
1130                if Base_Type (Tref) = Tref then
1131
1132                   --  If derived, then get first subtype
1133
1134                   if Tref /= Etype (Tref) then
1135                      Tref := First_Subtype (Etype (Tref));
1136
1137                      --  Set brackets for derived type, but don't override
1138                      --  pointer case since the fact that something is a
1139                      --  pointer is more important.
1140
1141                      if Left /= '(' then
1142                         Left := '<';
1143                         Right := '>';
1144                      end if;
1145
1146                   --  If non-derived ptr, get directly designated type.
1147                   --  If the type has a full view, all references are on the
1148                   --  partial view, that is seen first.
1149
1150                   elsif Is_Access_Type (Tref) then
1151                      Tref := Directly_Designated_Type (Tref);
1152                      Left := '(';
1153                      Right := ')';
1154
1155                   elsif Is_Private_Type (Tref)
1156                     and then Present (Full_View (Tref))
1157                   then
1158                      if Is_Access_Type (Full_View (Tref)) then
1159                         Tref := Directly_Designated_Type (Full_View (Tref));
1160                         Left := '(';
1161                         Right := ')';
1162
1163                      --  If the full view is an array type, we also retrieve
1164                      --  the corresponding component type, because the ali
1165                      --  entry already indicates that this is an array.
1166
1167                      elsif Is_Array_Type (Full_View (Tref)) then
1168                         Tref := Component_Type (Full_View (Tref));
1169                         Left := '(';
1170                         Right := ')';
1171                      end if;
1172
1173                   --  If non-derived array, get component type. Skip component
1174                   --  type for case of String or Wide_String, saves worthwhile
1175                   --  space.
1176
1177                   elsif Is_Array_Type (Tref)
1178                     and then Tref /= Standard_String
1179                     and then Tref /= Standard_Wide_String
1180                   then
1181                      Tref := Component_Type (Tref);
1182                      Left := '(';
1183                      Right := ')';
1184
1185                   --  For other non-derived base types, nothing
1186
1187                   else
1188                      exit;
1189                   end if;
1190
1191                --  For a subtype, go to ancestor subtype
1192
1193                else
1194                   Tref := Ancestor_Subtype (Tref);
1195
1196                   --  If no ancestor subtype, go to base type
1197
1198                   if No (Tref) then
1199                      Tref := Base_Type (Sav);
1200                   end if;
1201                end if;
1202
1203             --  For objects, functions, enum literals, just get type from
1204             --  Etype field.
1205
1206             elsif Is_Object (Tref)
1207               or else Ekind (Tref) = E_Enumeration_Literal
1208               or else Ekind (Tref) = E_Function
1209               or else Ekind (Tref) = E_Operator
1210             then
1211                Tref := Etype (Tref);
1212
1213             --  For anything else, exit
1214
1215             else
1216                exit;
1217             end if;
1218
1219             --  Exit if no type reference, or we are stuck in some loop trying
1220             --  to find the type reference, or if the type is standard void
1221             --  type (the latter is an implementation artifact that should not
1222             --  show up in the generated cross-references).
1223
1224             exit when No (Tref)
1225               or else Tref = Sav
1226               or else Tref = Standard_Void_Type;
1227
1228             --  If we have a usable type reference, return, otherwise keep
1229             --  looking for something useful (we are looking for something
1230             --  that either comes from source or standard)
1231
1232             if Sloc (Tref) = Standard_Location
1233               or else Comes_From_Source (Tref)
1234             then
1235                --  If the reference is a subtype created for a generic actual,
1236                --  go actual directly, the inner subtype is not user visible.
1237
1238                if Nkind (Parent (Tref)) = N_Subtype_Declaration
1239                  and then not Comes_From_Source (Parent (Tref))
1240                  and then
1241                   (Is_Wrapper_Package (Scope (Tref))
1242                      or else Is_Generic_Instance (Scope (Tref)))
1243                then
1244                   Tref := First_Subtype (Base_Type (Tref));
1245                end if;
1246
1247                return;
1248             end if;
1249          end loop;
1250
1251          --  If we fall through the loop, no type reference
1252
1253          Tref := Empty;
1254          Left := ' ';
1255          Right := ' ';
1256       end Get_Type_Reference;
1257
1258       -------------------------------
1259       -- Output_Import_Export_Info --
1260       -------------------------------
1261
1262       procedure Output_Import_Export_Info (Ent : Entity_Id) is
1263          Language_Name : Name_Id;
1264          Conv          : constant Convention_Id := Convention (Ent);
1265
1266       begin
1267          --  Generate language name from convention
1268
1269          if Conv  = Convention_C then
1270             Language_Name := Name_C;
1271
1272          elsif Conv = Convention_CPP then
1273             Language_Name := Name_CPP;
1274
1275          elsif Conv = Convention_Ada then
1276             Language_Name := Name_Ada;
1277
1278          else
1279             --  For the moment we ignore all other cases ???
1280
1281             return;
1282          end if;
1283
1284          Write_Info_Char ('<');
1285          Get_Unqualified_Name_String (Language_Name);
1286
1287          for J in 1 .. Name_Len loop
1288             Write_Info_Char (Name_Buffer (J));
1289          end loop;
1290
1291          if Present (Interface_Name (Ent)) then
1292             Write_Info_Char (',');
1293             String_To_Name_Buffer (Strval (Interface_Name (Ent)));
1294
1295             for J in 1 .. Name_Len loop
1296                Write_Info_Char (Name_Buffer (J));
1297             end loop;
1298          end if;
1299
1300          Write_Info_Char ('>');
1301       end Output_Import_Export_Info;
1302
1303    --  Start of processing for Output_References
1304
1305    begin
1306       --  First we add references to the primitive operations of tagged types
1307       --  declared in the main unit.
1308
1309       Handle_Prim_Ops : declare
1310          Ent  : Entity_Id;
1311
1312       begin
1313          for J in 1 .. Xrefs.Last loop
1314             Ent := Xrefs.Table (J).Ent;
1315
1316             if Is_Type (Ent)
1317               and then Is_Tagged_Type (Ent)
1318               and then Is_Base_Type (Ent)
1319               and then In_Extended_Main_Source_Unit (Ent)
1320             then
1321                Generate_Prim_Op_References (Ent);
1322             end if;
1323          end loop;
1324       end Handle_Prim_Ops;
1325
1326       --  Before we go ahead and output the references we have a problem
1327       --  that needs dealing with. So far we have captured things that are
1328       --  definitely referenced by the main unit, or defined in the main
1329       --  unit. That's because we don't want to clutter up the ali file
1330       --  for this unit with definition lines for entities in other units
1331       --  that are not referenced.
1332
1333       --  But there is a glitch. We may reference an entity in another unit,
1334       --  and it may have a type reference to an entity that is not directly
1335       --  referenced in the main unit, which may mean that there is no xref
1336       --  entry for this entity yet in the list of references.
1337
1338       --  If we don't do something about this, we will end with an orphan type
1339       --  reference, i.e. it will point to an entity that does not appear
1340       --  within the generated references in the ali file. That is not good for
1341       --  tools using the xref information.
1342
1343       --  To fix this, we go through the references adding definition entries
1344       --  for any unreferenced entities that can be referenced in a type
1345       --  reference. There is a recursion problem here, and that is dealt with
1346       --  by making sure that this traversal also traverses any entries that
1347       --  get added by the traversal.
1348
1349       Handle_Orphan_Type_References : declare
1350          J    : Nat;
1351          Tref : Entity_Id;
1352          Indx : Nat;
1353          Ent  : Entity_Id;
1354          Loc  : Source_Ptr;
1355
1356          L, R : Character;
1357          pragma Warnings (Off, L);
1358          pragma Warnings (Off, R);
1359
1360          procedure New_Entry (E : Entity_Id);
1361          --  Make an additional entry into the Xref table for a type entity
1362          --  that is related to the current entity (parent, type ancestor,
1363          --  progenitor, etc.).
1364
1365          ----------------
1366          -- New_Entry --
1367          ----------------
1368
1369          procedure New_Entry (E : Entity_Id) is
1370          begin
1371             if Present (E)
1372               and then not Has_Xref_Entry (E)
1373               and then Sloc (E) > No_Location
1374             then
1375                Xrefs.Increment_Last;
1376                Indx := Xrefs.Last;
1377                Loc  := Original_Location (Sloc (E));
1378                Xrefs.Table (Indx).Ent := E;
1379                Xrefs.Table (Indx).Loc := No_Location;
1380                Xrefs.Table (Indx).Eun := Get_Source_Unit (Loc);
1381                Xrefs.Table (Indx).Lun := No_Unit;
1382                Set_Has_Xref_Entry (E);
1383             end if;
1384          end New_Entry;
1385
1386       --  Start of processing for Handle_Orphan_Type_References
1387
1388       begin
1389          --  Note that this is not a for loop for a very good reason. The
1390          --  processing of items in the table can add new items to the table,
1391          --  and they must be processed as well.
1392
1393          J := 1;
1394          while J <= Xrefs.Last loop
1395             Ent := Xrefs.Table (J).Ent;
1396             Get_Type_Reference (Ent, Tref, L, R);
1397
1398             if Present (Tref)
1399               and then not Has_Xref_Entry (Tref)
1400               and then Sloc (Tref) > No_Location
1401             then
1402                New_Entry (Tref);
1403
1404                if Is_Record_Type (Ent)
1405                  and then Present (Interfaces (Ent))
1406                then
1407                   --  Add an entry for each one of the given interfaces
1408                   --  implemented by type Ent.
1409
1410                   declare
1411                      Elmt : Elmt_Id := First_Elmt (Interfaces (Ent));
1412                   begin
1413                      while Present (Elmt) loop
1414                         New_Entry (Node (Elmt));
1415                         Next_Elmt (Elmt);
1416                      end loop;
1417                   end;
1418                end if;
1419             end if;
1420
1421             --  Collect inherited primitive operations that may be declared in
1422             --  another unit and have no visible reference in the current one.
1423
1424             if Is_Type (Ent)
1425               and then Is_Tagged_Type (Ent)
1426               and then Is_Derived_Type (Ent)
1427               and then Is_Base_Type (Ent)
1428               and then In_Extended_Main_Source_Unit (Ent)
1429             then
1430                declare
1431                   Op_List : constant Elist_Id := Primitive_Operations (Ent);
1432                   Op      : Elmt_Id;
1433                   Prim    : Entity_Id;
1434
1435                   function Parent_Op (E : Entity_Id) return Entity_Id;
1436                   --  Find original operation, which may be inherited through
1437                   --  several derivations.
1438
1439                   function Parent_Op (E : Entity_Id) return Entity_Id is
1440                      Orig_Op : constant Entity_Id := Alias (E);
1441
1442                   begin
1443                      if No (Orig_Op) then
1444                         return Empty;
1445
1446                      elsif not Comes_From_Source (E)
1447                        and then not Has_Xref_Entry (Orig_Op)
1448                        and then Comes_From_Source (Orig_Op)
1449                      then
1450                         return Orig_Op;
1451                      else
1452                         return Parent_Op (Orig_Op);
1453                      end if;
1454                   end Parent_Op;
1455
1456                begin
1457                   Op := First_Elmt (Op_List);
1458                   while Present (Op) loop
1459                      Prim := Parent_Op (Node (Op));
1460
1461                      if Present (Prim) then
1462                         Xrefs.Increment_Last;
1463                         Indx := Xrefs.Last;
1464                         Loc  := Original_Location (Sloc (Prim));
1465                         Xrefs.Table (Indx).Ent := Prim;
1466                         Xrefs.Table (Indx).Loc := No_Location;
1467                         Xrefs.Table (Indx).Eun :=
1468                           Get_Source_Unit (Sloc (Prim));
1469                         Xrefs.Table (Indx).Lun := No_Unit;
1470                         Set_Has_Xref_Entry (Prim);
1471                      end if;
1472
1473                      Next_Elmt (Op);
1474                   end loop;
1475                end;
1476             end if;
1477
1478             J := J + 1;
1479          end loop;
1480       end Handle_Orphan_Type_References;
1481
1482       --  Now we have all the references, including those for any embedded
1483       --  type references, so we can sort them, and output them.
1484
1485       Output_Refs : declare
1486
1487          Nrefs : Nat := Xrefs.Last;
1488          --  Number of references in table. This value may get reset (reduced)
1489          --  when we eliminate duplicate reference entries.
1490
1491          Rnums : array (0 .. Nrefs) of Nat;
1492          --  This array contains numbers of references in the Xrefs table.
1493          --  This list is sorted in output order. The extra 0'th entry is
1494          --  convenient for the call to sort. When we sort the table, we
1495          --  move the entries in Rnums around, but we do not move the
1496          --  original table entries.
1497
1498          Curxu : Unit_Number_Type;
1499          --  Current xref unit
1500
1501          Curru : Unit_Number_Type;
1502          --  Current reference unit for one entity
1503
1504          Curent : Entity_Id;
1505          --  Current entity
1506
1507          Curnam : String (1 .. Name_Buffer'Length);
1508          Curlen : Natural;
1509          --  Simple name and length of current entity
1510
1511          Curdef : Source_Ptr;
1512          --  Original source location for current entity
1513
1514          Crloc : Source_Ptr;
1515          --  Current reference location
1516
1517          Ctyp : Character;
1518          --  Entity type character
1519
1520          Prevt : Character;
1521          --  reference kind of previous reference
1522
1523          Tref : Entity_Id;
1524          --  Type reference
1525
1526          Rref : Node_Id;
1527          --  Renaming reference
1528
1529          Trunit : Unit_Number_Type;
1530          --  Unit number for type reference
1531
1532          function Lt (Op1, Op2 : Natural) return Boolean;
1533          --  Comparison function for Sort call
1534
1535          function Name_Change (X : Entity_Id) return Boolean;
1536          --  Determines if entity X has a different simple name from Curent
1537
1538          procedure Move (From : Natural; To : Natural);
1539          --  Move procedure for Sort call
1540
1541          package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
1542
1543          --------
1544          -- Lt --
1545          --------
1546
1547          function Lt (Op1, Op2 : Natural) return Boolean is
1548             T1 : Xref_Entry renames Xrefs.Table (Rnums (Nat (Op1)));
1549             T2 : Xref_Entry renames Xrefs.Table (Rnums (Nat (Op2)));
1550
1551          begin
1552             return Lt (T1, T2);
1553          end Lt;
1554
1555          ----------
1556          -- Move --
1557          ----------
1558
1559          procedure Move (From : Natural; To : Natural) is
1560          begin
1561             Rnums (Nat (To)) := Rnums (Nat (From));
1562          end Move;
1563
1564          -----------------
1565          -- Name_Change --
1566          -----------------
1567
1568          --  Why a string comparison here??? Why not compare Name_Id values???
1569
1570          function Name_Change (X : Entity_Id) return Boolean is
1571          begin
1572             Get_Unqualified_Name_String (Chars (X));
1573
1574             if Name_Len /= Curlen then
1575                return True;
1576             else
1577                return Name_Buffer (1 .. Curlen) /= Curnam (1 .. Curlen);
1578             end if;
1579          end Name_Change;
1580
1581       --  Start of processing for Output_Refs
1582
1583       begin
1584          --  Capture the definition Sloc values. We delay doing this till now,
1585          --  since at the time the reference or definition is made, private
1586          --  types may be swapped, and the Sloc value may be incorrect. We
1587          --  also set up the pointer vector for the sort.
1588
1589          for J in 1 .. Nrefs loop
1590             Rnums (J) := J;
1591             Xrefs.Table (J).Def :=
1592               Original_Location (Sloc (Xrefs.Table (J).Ent));
1593          end loop;
1594
1595          --  Sort the references
1596
1597          Sorting.Sort (Integer (Nrefs));
1598
1599          --  Eliminate duplicate entries
1600
1601          declare
1602             NR : constant Nat := Nrefs;
1603
1604          begin
1605             --  We need this test for NR because if we force ALI file
1606             --  generation in case of errors detected, it may be the case
1607             --  that Nrefs is 0, so we should not reset it here
1608
1609             if NR >= 2 then
1610                Nrefs := 1;
1611
1612                for J in 2 .. NR loop
1613                   if Xrefs.Table (Rnums (J)) /=
1614                      Xrefs.Table (Rnums (Nrefs))
1615                   then
1616                      Nrefs := Nrefs + 1;
1617                      Rnums (Nrefs) := Rnums (J);
1618                   end if;
1619                end loop;
1620             end if;
1621          end;
1622
1623          --  Initialize loop through references
1624
1625          Curxu  := No_Unit;
1626          Curent := Empty;
1627          Curdef := No_Location;
1628          Curru  := No_Unit;
1629          Crloc  := No_Location;
1630          Prevt  := 'm';
1631
1632          --  Loop to output references
1633
1634          for Refno in 1 .. Nrefs loop
1635             Output_One_Ref : declare
1636                Ent : Entity_Id;
1637
1638                XE : Xref_Entry renames Xrefs.Table (Rnums (Refno));
1639                --  The current entry to be accessed
1640
1641                Left  : Character;
1642                Right : Character;
1643                --  Used for {} or <> or () for type reference
1644
1645                procedure Check_Type_Reference
1646                  (Ent            : Entity_Id;
1647                   List_Interface : Boolean);
1648                --  Find whether there is a meaningful type reference for
1649                --  Ent, and display it accordingly. If List_Interface is
1650                --  true, then Ent is a progenitor interface of the current
1651                --  type entity being listed. In that case list it as is,
1652                --  without looking for a type reference for it.
1653
1654                procedure Output_Instantiation_Refs (Loc : Source_Ptr);
1655                --  Recursive procedure to output instantiation references for
1656                --  the given source ptr in [file|line[...]] form. No output
1657                --  if the given location is not a generic template reference.
1658
1659                procedure Output_Overridden_Op (Old_E : Entity_Id);
1660                --  For a subprogram that is overriding, display information
1661                --  about the inherited operation that it overrides.
1662
1663                --------------------------
1664                -- Check_Type_Reference --
1665                --------------------------
1666
1667                procedure Check_Type_Reference
1668                  (Ent            : Entity_Id;
1669                   List_Interface : Boolean)
1670                is
1671                begin
1672                   if List_Interface then
1673
1674                      --  This is a progenitor interface of the type for which
1675                      --  xref information is being generated.
1676
1677                      Tref  := Ent;
1678                      Left  := '<';
1679                      Right := '>';
1680
1681                   else
1682                      Get_Type_Reference (Ent, Tref, Left, Right);
1683                   end if;
1684
1685                   if Present (Tref) then
1686
1687                      --  Case of standard entity, output name
1688
1689                      if Sloc (Tref) = Standard_Location then
1690                         Write_Info_Char (Left);
1691                         Write_Info_Name (Chars (Tref));
1692                         Write_Info_Char (Right);
1693
1694                      --  Case of source entity, output location
1695
1696                      else
1697                         Write_Info_Char (Left);
1698                         Trunit := Get_Source_Unit (Sloc (Tref));
1699
1700                         if Trunit /= Curxu then
1701                            Write_Info_Nat (Dependency_Num (Trunit));
1702                            Write_Info_Char ('|');
1703                         end if;
1704
1705                         Write_Info_Nat
1706                           (Int (Get_Logical_Line_Number (Sloc (Tref))));
1707
1708                         declare
1709                            Ent  : Entity_Id;
1710                            Ctyp : Character;
1711
1712                         begin
1713                            Ent := Tref;
1714                            Ctyp := Xref_Entity_Letters (Ekind (Ent));
1715
1716                            if Ctyp = '+'
1717                              and then Present (Full_View (Ent))
1718                            then
1719                               Ent := Underlying_Type (Ent);
1720
1721                               if Present (Ent) then
1722                                  Ctyp := Xref_Entity_Letters (Ekind (Ent));
1723                               end if;
1724                            end if;
1725
1726                            Write_Info_Char (Ctyp);
1727                         end;
1728
1729                         Write_Info_Nat
1730                           (Int (Get_Column_Number (Sloc (Tref))));
1731
1732                         --  If the type comes from an instantiation, add the
1733                         --  corresponding info.
1734
1735                         Output_Instantiation_Refs (Sloc (Tref));
1736                         Write_Info_Char (Right);
1737                      end if;
1738                   end if;
1739                end Check_Type_Reference;
1740
1741                -------------------------------
1742                -- Output_Instantiation_Refs --
1743                -------------------------------
1744
1745                procedure Output_Instantiation_Refs (Loc : Source_Ptr) is
1746                   Iloc : constant Source_Ptr := Instantiation_Location (Loc);
1747                   Lun  : Unit_Number_Type;
1748                   Cu   : constant Unit_Number_Type := Curru;
1749
1750                begin
1751                   --  Nothing to do if this is not an instantiation
1752
1753                   if Iloc = No_Location then
1754                      return;
1755                   end if;
1756
1757                   --  Output instantiation reference
1758
1759                   Write_Info_Char ('[');
1760                   Lun := Get_Source_Unit (Iloc);
1761
1762                   if Lun /= Curru then
1763                      Curru := Lun;
1764                      Write_Info_Nat (Dependency_Num (Curru));
1765                      Write_Info_Char ('|');
1766                   end if;
1767
1768                   Write_Info_Nat (Int (Get_Logical_Line_Number (Iloc)));
1769
1770                   --  Recursive call to get nested instantiations
1771
1772                   Output_Instantiation_Refs (Iloc);
1773
1774                   --  Output final ] after call to get proper nesting
1775
1776                   Write_Info_Char (']');
1777                   Curru := Cu;
1778                   return;
1779                end Output_Instantiation_Refs;
1780
1781                --------------------------
1782                -- Output_Overridden_Op --
1783                --------------------------
1784
1785                procedure Output_Overridden_Op (Old_E : Entity_Id) is
1786                   Op : Entity_Id;
1787
1788                begin
1789                   --  The overridden operation has an implicit declaration
1790                   --  at the point of derivation. What we want to display
1791                   --  is the original operation, which has the actual body
1792                   --  (or abstract declaration) that is being overridden.
1793                   --  The overridden operation is not always set, e.g. when
1794                   --  it is a predefined operator.
1795
1796                   if No (Old_E) then
1797                      return;
1798
1799                   --  Follow alias chain if one is present
1800
1801                   elsif Present (Alias (Old_E)) then
1802
1803                      --  The subprogram may have been implicitly inherited
1804                      --  through several levels of derivation, so find the
1805                      --  ultimate (source) ancestor.
1806
1807                      Op := Ultimate_Alias (Old_E);
1808
1809                   --  Normal case of no alias present
1810
1811                   else
1812                      Op := Old_E;
1813                   end if;
1814
1815                   if Present (Op)
1816                     and then Sloc (Op) /= Standard_Location
1817                   then
1818                      declare
1819                         Loc      : constant Source_Ptr := Sloc (Op);
1820                         Par_Unit : constant Unit_Number_Type :=
1821                                      Get_Source_Unit (Loc);
1822
1823                      begin
1824                         Write_Info_Char ('<');
1825
1826                         if Par_Unit /= Curxu then
1827                            Write_Info_Nat (Dependency_Num (Par_Unit));
1828                            Write_Info_Char ('|');
1829                         end if;
1830
1831                         Write_Info_Nat (Int (Get_Logical_Line_Number (Loc)));
1832                         Write_Info_Char ('p');
1833                         Write_Info_Nat (Int (Get_Column_Number (Loc)));
1834                         Write_Info_Char ('>');
1835                      end;
1836                   end if;
1837                end Output_Overridden_Op;
1838
1839             --  Start of processing for Output_One_Ref
1840
1841             begin
1842                Ent := XE.Ent;
1843                Ctyp := Xref_Entity_Letters (Ekind (Ent));
1844
1845                --  Skip reference if it is the only reference to an entity,
1846                --  and it is an END line reference, and the entity is not in
1847                --  the current extended source. This prevents junk entries
1848                --  consisting only of packages with END lines, where no
1849                --  entity from the package is actually referenced.
1850
1851                if XE.Typ = 'e'
1852                  and then Ent /= Curent
1853                  and then (Refno = Nrefs or else
1854                              Ent /= Xrefs.Table (Rnums (Refno + 1)).Ent)
1855                  and then
1856                    not In_Extended_Main_Source_Unit (Ent)
1857                then
1858                   goto Continue;
1859                end if;
1860
1861                --  For private type, get full view type
1862
1863                if Ctyp = '+'
1864                  and then Present (Full_View (XE.Ent))
1865                then
1866                   Ent := Underlying_Type (Ent);
1867
1868                   if Present (Ent) then
1869                      Ctyp := Xref_Entity_Letters (Ekind (Ent));
1870                   end if;
1871                end if;
1872
1873                --  Special exception for Boolean
1874
1875                if Ctyp = 'E' and then Is_Boolean_Type (Ent) then
1876                   Ctyp := 'B';
1877                end if;
1878
1879                --  For variable reference, get corresponding type
1880
1881                if Ctyp = '*' then
1882                   Ent := Etype (XE.Ent);
1883                   Ctyp := Fold_Lower (Xref_Entity_Letters (Ekind (Ent)));
1884
1885                   --  If variable is private type, get full view type
1886
1887                   if Ctyp = '+'
1888                     and then Present (Full_View (Etype (XE.Ent)))
1889                   then
1890                      Ent := Underlying_Type (Etype (XE.Ent));
1891
1892                      if Present (Ent) then
1893                         Ctyp := Fold_Lower (Xref_Entity_Letters (Ekind (Ent)));
1894                      end if;
1895
1896                   elsif Is_Generic_Type (Ent) then
1897
1898                      --  If the type of the entity is a generic private type,
1899                      --  there is no usable full view, so retain the indication
1900                      --  that this is an object.
1901
1902                      Ctyp := '*';
1903                   end if;
1904
1905                   --  Special handling for access parameters and objects of
1906                   --  an anonymous access type.
1907
1908                   if Ekind_In (Etype (XE.Ent),
1909                                E_Anonymous_Access_Type,
1910                                E_Anonymous_Access_Subprogram_Type,
1911                                E_Anonymous_Access_Protected_Subprogram_Type)
1912                   then
1913                      if Is_Formal (XE.Ent)
1914                        or else Ekind_In (XE.Ent, E_Variable, E_Constant)
1915                      then
1916                         Ctyp := 'p';
1917                      end if;
1918
1919                      --  Special handling for Boolean
1920
1921                   elsif Ctyp = 'e' and then Is_Boolean_Type (Ent) then
1922                      Ctyp := 'b';
1923                   end if;
1924                end if;
1925
1926                --  Special handling for abstract types and operations
1927
1928                if Is_Overloadable (XE.Ent)
1929                  and then Is_Abstract_Subprogram (XE.Ent)
1930                then
1931                   if Ctyp = 'U' then
1932                      Ctyp := 'x';            --  Abstract procedure
1933
1934                   elsif Ctyp = 'V' then
1935                      Ctyp := 'y';            --  Abstract function
1936                   end if;
1937
1938                elsif Is_Type (XE.Ent)
1939                  and then Is_Abstract_Type (XE.Ent)
1940                then
1941                   if Is_Interface (XE.Ent) then
1942                      Ctyp := 'h';
1943
1944                   elsif Ctyp = 'R' then
1945                      Ctyp := 'H';            --  Abstract type
1946                   end if;
1947                end if;
1948
1949                --  Only output reference if interesting type of entity
1950
1951                if Ctyp = ' '
1952
1953                --  Suppress references to object definitions, used for local
1954                --  references.
1955
1956                  or else XE.Typ = 'D'
1957                  or else XE.Typ = 'I'
1958
1959                --  Suppress self references, except for bodies that act as
1960                --  specs.
1961
1962                  or else (XE.Loc = XE.Def
1963                            and then
1964                              (XE.Typ /= 'b'
1965                                or else not Is_Subprogram (XE.Ent)))
1966
1967                --  Also suppress definitions of body formals (we only
1968                --  treat these as references, and the references were
1969                --  separately recorded).
1970
1971                  or else (Is_Formal (XE.Ent)
1972                            and then Present (Spec_Entity (XE.Ent)))
1973                then
1974                   null;
1975
1976                else
1977                   --  Start new Xref section if new xref unit
1978
1979                   if XE.Eun /= Curxu then
1980                      if Write_Info_Col > 1 then
1981                         Write_Info_EOL;
1982                      end if;
1983
1984                      Curxu := XE.Eun;
1985
1986                      Write_Info_Initiate ('X');
1987                      Write_Info_Char (' ');
1988                      Write_Info_Nat (Dependency_Num (XE.Eun));
1989                      Write_Info_Char (' ');
1990                      Write_Info_Name (Reference_Name (Source_Index (XE.Eun)));
1991                   end if;
1992
1993                   --  Start new Entity line if new entity. Note that we
1994                   --  consider two entities the same if they have the same
1995                   --  name and source location. This causes entities in
1996                   --  instantiations to be treated as though they referred
1997                   --  to the template.
1998
1999                   if No (Curent)
2000                     or else
2001                       (XE.Ent /= Curent
2002                          and then
2003                            (Name_Change (XE.Ent) or else XE.Def /= Curdef))
2004                   then
2005                      Curent := XE.Ent;
2006                      Curdef := XE.Def;
2007
2008                      Get_Unqualified_Name_String (Chars (XE.Ent));
2009                      Curlen := Name_Len;
2010                      Curnam (1 .. Curlen) := Name_Buffer (1 .. Curlen);
2011
2012                      if Write_Info_Col > 1 then
2013                         Write_Info_EOL;
2014                      end if;
2015
2016                      --  Write column number information
2017
2018                      Write_Info_Nat (Int (Get_Logical_Line_Number (XE.Def)));
2019                      Write_Info_Char (Ctyp);
2020                      Write_Info_Nat (Int (Get_Column_Number (XE.Def)));
2021
2022                      --  Write level information
2023
2024                      Write_Level_Info : declare
2025                         function Is_Visible_Generic_Entity
2026                           (E : Entity_Id) return Boolean;
2027                         --  Check whether E is declared in the visible part
2028                         --  of a generic package. For source navigation
2029                         --  purposes, treat this as a visible entity.
2030
2031                         function Is_Private_Record_Component
2032                           (E : Entity_Id) return Boolean;
2033                         --  Check whether E is a non-inherited component of a
2034                         --  private extension. Even if the enclosing record is
2035                         --  public, we want to treat the component as private
2036                         --  for navigation purposes.
2037
2038                         ---------------------------------
2039                         -- Is_Private_Record_Component --
2040                         ---------------------------------
2041
2042                         function Is_Private_Record_Component
2043                           (E : Entity_Id) return Boolean
2044                         is
2045                            S : constant Entity_Id := Scope (E);
2046                         begin
2047                            return
2048                              Ekind (E) = E_Component
2049                                and then Nkind (Declaration_Node (S)) =
2050                                  N_Private_Extension_Declaration
2051                                and then Original_Record_Component (E) = E;
2052                         end Is_Private_Record_Component;
2053
2054                         -------------------------------
2055                         -- Is_Visible_Generic_Entity --
2056                         -------------------------------
2057
2058                         function Is_Visible_Generic_Entity
2059                           (E : Entity_Id) return Boolean
2060                         is
2061                            Par : Node_Id;
2062
2063                         begin
2064                            --  The Present check here is an error defense
2065
2066                            if Present (Scope (E))
2067                              and then Ekind (Scope (E)) /= E_Generic_Package
2068                            then
2069                               return False;
2070                            end if;
2071
2072                            Par := Parent (E);
2073                            while Present (Par) loop
2074                               if
2075                                 Nkind (Par) = N_Generic_Package_Declaration
2076                               then
2077                                  --  Entity is a generic formal
2078
2079                                  return False;
2080
2081                               elsif
2082                                 Nkind (Parent (Par)) = N_Package_Specification
2083                               then
2084                                  return
2085                                    Is_List_Member (Par)
2086                                      and then List_Containing (Par) =
2087                                        Visible_Declarations (Parent (Par));
2088                               else
2089                                  Par := Parent (Par);
2090                               end if;
2091                            end loop;
2092
2093                            return False;
2094                         end Is_Visible_Generic_Entity;
2095
2096                      --  Start of processing for Write_Level_Info
2097
2098                      begin
2099                         if Is_Hidden (Curent)
2100                           or else Is_Private_Record_Component (Curent)
2101                         then
2102                            Write_Info_Char (' ');
2103
2104                         elsif
2105                            Is_Public (Curent)
2106                              or else Is_Visible_Generic_Entity (Curent)
2107                         then
2108                            Write_Info_Char ('*');
2109
2110                         else
2111                            Write_Info_Char (' ');
2112                         end if;
2113                      end Write_Level_Info;
2114
2115                      --  Output entity name. We use the occurrence from the
2116                      --  actual source program at the definition point.
2117
2118                      declare
2119                         Ent_Name : constant String :=
2120                                      Exact_Source_Name (Sloc (XE.Ent));
2121                      begin
2122                         for C in Ent_Name'Range loop
2123                            Write_Info_Char (Ent_Name (C));
2124                         end loop;
2125                      end;
2126
2127                      --  See if we have a renaming reference
2128
2129                      if Is_Object (XE.Ent)
2130                        and then Present (Renamed_Object (XE.Ent))
2131                      then
2132                         Rref := Renamed_Object (XE.Ent);
2133
2134                      elsif Is_Overloadable (XE.Ent)
2135                        and then Nkind (Parent (Declaration_Node (XE.Ent))) =
2136                                             N_Subprogram_Renaming_Declaration
2137                      then
2138                         Rref := Name (Parent (Declaration_Node (XE.Ent)));
2139
2140                      elsif Ekind (XE.Ent) = E_Package
2141                        and then Nkind (Declaration_Node (XE.Ent)) =
2142                                          N_Package_Renaming_Declaration
2143                      then
2144                         Rref := Name (Declaration_Node (XE.Ent));
2145
2146                      else
2147                         Rref := Empty;
2148                      end if;
2149
2150                      if Present (Rref) then
2151                         if Nkind (Rref) = N_Expanded_Name then
2152                            Rref := Selector_Name (Rref);
2153                         end if;
2154
2155                         if Nkind (Rref) = N_Identifier
2156                           or else Nkind (Rref) = N_Operator_Symbol
2157                         then
2158                            null;
2159
2160                         --  For renamed array components, use the array name
2161                         --  for the renamed entity, which reflect the fact that
2162                         --  in general the whole array is aliased.
2163
2164                         elsif Nkind (Rref) = N_Indexed_Component then
2165                            if Nkind (Prefix (Rref)) = N_Identifier then
2166                               Rref := Prefix (Rref);
2167                            elsif Nkind (Prefix (Rref)) = N_Expanded_Name then
2168                               Rref := Selector_Name (Prefix (Rref));
2169                            else
2170                               Rref := Empty;
2171                            end if;
2172
2173                         else
2174                            Rref := Empty;
2175                         end if;
2176                      end if;
2177
2178                      --  Write out renaming reference if we have one
2179
2180                      if Present (Rref) then
2181                         Write_Info_Char ('=');
2182                         Write_Info_Nat
2183                           (Int (Get_Logical_Line_Number (Sloc (Rref))));
2184                         Write_Info_Char (':');
2185                         Write_Info_Nat
2186                           (Int (Get_Column_Number (Sloc (Rref))));
2187                      end if;
2188
2189                      --  Indicate that the entity is in the unit of the current
2190                      --  xref section.
2191
2192                      Curru := Curxu;
2193
2194                      --  Write out information about generic parent, if entity
2195                      --  is an instance.
2196
2197                      if  Is_Generic_Instance (XE.Ent) then
2198                         declare
2199                            Gen_Par : constant Entity_Id :=
2200                                        Generic_Parent
2201                                          (Specification
2202                                             (Unit_Declaration_Node (XE.Ent)));
2203                            Loc     : constant Source_Ptr := Sloc (Gen_Par);
2204                            Gen_U   : constant Unit_Number_Type :=
2205                                        Get_Source_Unit (Loc);
2206
2207                         begin
2208                            Write_Info_Char ('[');
2209
2210                            if Curru /= Gen_U then
2211                               Write_Info_Nat (Dependency_Num (Gen_U));
2212                               Write_Info_Char ('|');
2213                            end if;
2214
2215                            Write_Info_Nat
2216                              (Int (Get_Logical_Line_Number (Loc)));
2217                            Write_Info_Char (']');
2218                         end;
2219                      end if;
2220
2221                      --  See if we have a type reference and if so output
2222
2223                      Check_Type_Reference (XE.Ent, False);
2224
2225                      --  Additional information for types with progenitors
2226
2227                      if Is_Record_Type (XE.Ent)
2228                        and then Present (Interfaces (XE.Ent))
2229                      then
2230                         declare
2231                            Elmt : Elmt_Id := First_Elmt (Interfaces (XE.Ent));
2232                         begin
2233                            while Present (Elmt) loop
2234                               Check_Type_Reference (Node (Elmt), True);
2235                               Next_Elmt (Elmt);
2236                            end loop;
2237                         end;
2238
2239                      --  For array types, list index types as well. (This is
2240                      --  not C, indexes have distinct types).
2241
2242                      elsif Is_Array_Type (XE.Ent) then
2243                         declare
2244                            Indx : Node_Id;
2245                         begin
2246                            Indx := First_Index (XE.Ent);
2247                            while Present (Indx) loop
2248                               Check_Type_Reference
2249                                 (First_Subtype (Etype (Indx)), True);
2250                               Next_Index (Indx);
2251                            end loop;
2252                         end;
2253                      end if;
2254
2255                      --  If the entity is an overriding operation, write info
2256                      --  on operation that was overridden.
2257
2258                      if Is_Subprogram (XE.Ent)
2259                        and then Present (Overridden_Operation (XE.Ent))
2260                      then
2261                         Output_Overridden_Op (Overridden_Operation (XE.Ent));
2262                      end if;
2263
2264                      --  End of processing for entity output
2265
2266                      Crloc := No_Location;
2267                   end if;
2268
2269                   --  Output the reference if it is not as the same location
2270                   --  as the previous one, or it is a read-reference that
2271                   --  indicates that the entity is an in-out actual in a call.
2272
2273                   if XE.Loc /= No_Location
2274                     and then
2275                       (XE.Loc /= Crloc
2276                         or else (Prevt = 'm' and then  XE.Typ = 'r'))
2277                   then
2278                      Crloc := XE.Loc;
2279                      Prevt := XE.Typ;
2280
2281                      --  Start continuation if line full, else blank
2282
2283                      if Write_Info_Col > 72 then
2284                         Write_Info_EOL;
2285                         Write_Info_Initiate ('.');
2286                      end if;
2287
2288                      Write_Info_Char (' ');
2289
2290                      --  Output file number if changed
2291
2292                      if XE.Lun /= Curru then
2293                         Curru := XE.Lun;
2294                         Write_Info_Nat (Dependency_Num (Curru));
2295                         Write_Info_Char ('|');
2296                      end if;
2297
2298                      Write_Info_Nat  (Int (Get_Logical_Line_Number (XE.Loc)));
2299                      Write_Info_Char (XE.Typ);
2300
2301                      if Is_Overloadable (XE.Ent)
2302                        and then Is_Imported (XE.Ent)
2303                        and then XE.Typ = 'b'
2304                      then
2305                         Output_Import_Export_Info (XE.Ent);
2306                      end if;
2307
2308                      Write_Info_Nat (Int (Get_Column_Number (XE.Loc)));
2309
2310                      Output_Instantiation_Refs (Sloc (XE.Ent));
2311                   end if;
2312                end if;
2313             end Output_One_Ref;
2314
2315          <<Continue>>
2316             null;
2317          end loop;
2318
2319          Write_Info_EOL;
2320       end Output_Refs;
2321    end Output_References;
2322
2323 end Lib.Xref;