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) 1998-2013, 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 with GNAT.HTable;
  48
  49 package body Lib.Xref is
  50
  51    ------------------
  52    -- Declarations --
  53    ------------------
  54
  55    --  The Xref table is used to record references. The Loc field is set
  56    --  to No_Location for a definition entry.
  57
  58    subtype Xref_Entry_Number is Int;
  59
  60    type Xref_Key is record
  61       --  These are the components of Xref_Entry that participate in hash
  62       --  lookups.
  63
  64       Ent : Entity_Id;
  65       --  Entity referenced (E parameter to Generate_Reference)
  66
  67       Loc : Source_Ptr;
  68       --  Location of reference (Original_Location (Sloc field of N parameter
  69       --  to Generate_Reference). Set to No_Location for the case of a
  70       --  defining occurrence.
  71
  72       Typ : Character;
  73       --  Reference type (Typ param to Generate_Reference)
  74
  75       Eun : Unit_Number_Type;
  76       --  Unit number corresponding to Ent
  77
  78       Lun : Unit_Number_Type;
  79       --  Unit number corresponding to Loc. Value is undefined and not
  80       --  referenced if Loc is set to No_Location.
  81
  82       --  The following components are only used for Alfa cross-references
  83
  84       Ref_Scope : Entity_Id;
  85       --  Entity of the closest subprogram or package enclosing the reference
  86
  87       Ent_Scope : Entity_Id;
  88       --  Entity of the closest subprogram or package enclosing the definition,
  89       --  which should be located in the same file as the definition itself.
  90    end record;
  91
  92    type Xref_Entry is record
  93       Key : Xref_Key;
  94
  95       Ent_Scope_File : Unit_Number_Type;
  96       --  File for entity Ent_Scope
  97
  98       Def : Source_Ptr;
  99       --  Original source location for entity being referenced. Note that these
 100       --  values are used only during the output process, they are not set when
 101       --  the entries are originally built. This is because private entities
 102       --  can be swapped when the initial call is made.
 103
 104       HTable_Next : Xref_Entry_Number;
 105       --  For use only by Static_HTable
 106    end record;
 107
 108    package Xrefs is new Table.Table (
 109      Table_Component_Type => Xref_Entry,
 110      Table_Index_Type     => Xref_Entry_Number,
 111      Table_Low_Bound      => 1,
 112      Table_Initial        => Alloc.Xrefs_Initial,
 113      Table_Increment      => Alloc.Xrefs_Increment,
 114      Table_Name           => "Xrefs");
 115
 116    --------------
 117    -- Xref_Set --
 118    --------------
 119
 120    --  We keep a set of xref entries, in order to avoid inserting duplicate
 121    --  entries into the above Xrefs table. An entry is in Xref_Set if and only
 122    --  if it is in Xrefs.
 123
 124    Num_Buckets : constant := 2**16;
 125
 126    subtype Header_Num is Integer range 0 .. Num_Buckets - 1;
 127    type Null_Type is null record;
 128    pragma Unreferenced (Null_Type);
 129
 130    function Hash (F : Xref_Entry_Number) return Header_Num;
 131
 132    function Equal (F1, F2 : Xref_Entry_Number) return Boolean;
 133
 134    procedure HT_Set_Next (E : Xref_Entry_Number; Next : Xref_Entry_Number);
 135
 136    function  HT_Next (E : Xref_Entry_Number) return Xref_Entry_Number;
 137
 138    function Get_Key (E : Xref_Entry_Number) return Xref_Entry_Number;
 139
 140    pragma Inline (Hash, Equal, HT_Set_Next, HT_Next, Get_Key);
 141
 142    package Xref_Set is new GNAT.HTable.Static_HTable (
 143      Header_Num,
 144      Element    => Xref_Entry,
 145      Elmt_Ptr   => Xref_Entry_Number,
 146      Null_Ptr   => 0,
 147      Set_Next   => HT_Set_Next,
 148      Next       => HT_Next,
 149      Key        => Xref_Entry_Number,
 150      Get_Key    => Get_Key,
 151      Hash       => Hash,
 152      Equal      => Equal);
 153
 154    ----------------------
 155    -- Alfa Information --
 156    ----------------------
 157
 158    package body Alfa is separate;
 159
 160    ------------------------
 161    --  Local Subprograms --
 162    ------------------------
 163
 164    procedure Add_Entry (Key : Xref_Key; Ent_Scope_File : Unit_Number_Type);
 165    --  Add an entry to the tables of Xref_Entries, avoiding duplicates
 166
 167    procedure Generate_Prim_Op_References (Typ : Entity_Id);
 168    --  For a tagged type, generate implicit references to its primitive
 169    --  operations, for source navigation. This is done right before emitting
 170    --  cross-reference information rather than at the freeze point of the type
 171    --  in order to handle late bodies that are primitive operations.
 172
 173    function Lt (T1, T2 : Xref_Entry) return Boolean;
 174    --  Order cross-references
 175
 176    ---------------
 177    -- Add_Entry --
 178    ---------------
 179
 180    procedure Add_Entry (Key : Xref_Key; Ent_Scope_File : Unit_Number_Type) is
 181    begin
 182       Xrefs.Increment_Last; -- tentative
 183       Xrefs.Table (Xrefs.Last).Key := Key;
 184
 185       --  Set the entry in Xref_Set, and if newly set, keep the above
 186       --  tentative increment.
 187
 188       if Xref_Set.Set_If_Not_Present (Xrefs.Last) then
 189          Xrefs.Table (Xrefs.Last).Ent_Scope_File := Ent_Scope_File;
 190          --  Leave Def and HTable_Next uninitialized
 191
 192          Set_Has_Xref_Entry (Key.Ent);
 193
 194       --  It was already in Xref_Set, so throw away the tentatively-added
 195       --  entry
 196
 197       else
 198          Xrefs.Decrement_Last;
 199       end if;
 200    end Add_Entry;
 201
 202    -----------
 203    -- Equal --
 204    -----------
 205
 206    function Equal (F1, F2 : Xref_Entry_Number) return Boolean is
 207       Result : constant Boolean :=
 208                  Xrefs.Table (F1).Key = Xrefs.Table (F2).Key;
 209    begin
 210       return Result;
 211    end Equal;
 212
 213    -------------------------
 214    -- Generate_Definition --
 215    -------------------------
 216
 217    procedure Generate_Definition (E : Entity_Id) is
 218    begin
 219       pragma Assert (Nkind (E) in N_Entity);
 220
 221       --  Note that we do not test Xref_Entity_Letters here. It is too early
 222       --  to do so, since we are often called before the entity is fully
 223       --  constructed, so that the Ekind is still E_Void.
 224
 225       if Opt.Xref_Active
 226
 227          --  Definition must come from source
 228
 229          --  We make an exception for subprogram child units that have no spec.
 230          --  For these we generate a subprogram declaration for library use,
 231          --  and the corresponding entity does not come from source.
 232          --  Nevertheless, all references will be attached to it and we have
 233          --  to treat is as coming from user code.
 234
 235          and then (Comes_From_Source (E) or else Is_Child_Unit (E))
 236
 237          --  And must have a reasonable source location that is not
 238          --  within an instance (all entities in instances are ignored)
 239
 240          and then Sloc (E) > No_Location
 241          and then Instantiation_Location (Sloc (E)) = No_Location
 242
 243          --  And must be a non-internal name from the main source unit
 244
 245          and then In_Extended_Main_Source_Unit (E)
 246          and then not Is_Internal_Name (Chars (E))
 247       then
 248          Add_Entry
 249            ((Ent => E,
 250              Loc => No_Location,
 251              Typ => ' ',
 252              Eun => Get_Source_Unit (Original_Location (Sloc (E))),
 253              Lun => No_Unit,
 254              Ref_Scope => Empty,
 255              Ent_Scope => Empty),
 256             Ent_Scope_File => No_Unit);
 257
 258          if In_Inlined_Body then
 259             Set_Referenced (E);
 260          end if;
 261       end if;
 262    end Generate_Definition;
 263
 264    ---------------------------------
 265    -- Generate_Operator_Reference --
 266    ---------------------------------
 267
 268    procedure Generate_Operator_Reference
 269      (N : Node_Id;
 270       T : Entity_Id)
 271    is
 272    begin
 273       if not In_Extended_Main_Source_Unit (N) then
 274          return;
 275       end if;
 276
 277       --  If the operator is not a Standard operator, then we generate a real
 278       --  reference to the user defined operator.
 279
 280       if Sloc (Entity (N)) /= Standard_Location then
 281          Generate_Reference (Entity (N), N);
 282
 283          --  A reference to an implicit inequality operator is also a reference
 284          --  to the user-defined equality.
 285
 286          if Nkind (N) = N_Op_Ne
 287            and then not Comes_From_Source (Entity (N))
 288            and then Present (Corresponding_Equality (Entity (N)))
 289          then
 290             Generate_Reference (Corresponding_Equality (Entity (N)), N);
 291          end if;
 292
 293       --  For the case of Standard operators, we mark the result type as
 294       --  referenced. This ensures that in the case where we are using a
 295       --  derived operator, we mark an entity of the unit that implicitly
 296       --  defines this operator as used. Otherwise we may think that no entity
 297       --  of the unit is used. The actual entity marked as referenced is the
 298       --  first subtype, which is the relevant user defined entity.
 299
 300       --  Note: we only do this for operators that come from source. The
 301       --  generated code sometimes reaches for entities that do not need to be
 302       --  explicitly visible (for example, when we expand the code for
 303       --  comparing two record objects, the fields of the record may not be
 304       --  visible).
 305
 306       elsif Comes_From_Source (N) then
 307          Set_Referenced (First_Subtype (T));
 308       end if;
 309    end Generate_Operator_Reference;
 310
 311    ---------------------------------
 312    -- Generate_Prim_Op_References --
 313    ---------------------------------
 314
 315    procedure Generate_Prim_Op_References (Typ : Entity_Id) is
 316       Base_T    : Entity_Id;
 317       Prim      : Elmt_Id;
 318       Prim_List : Elist_Id;
 319
 320    begin
 321       --  Handle subtypes of synchronized types
 322
 323       if Ekind (Typ) = E_Protected_Subtype
 324         or else Ekind (Typ) = E_Task_Subtype
 325       then
 326          Base_T := Etype (Typ);
 327       else
 328          Base_T := Typ;
 329       end if;
 330
 331       --  References to primitive operations are only relevant for tagged types
 332
 333       if not Is_Tagged_Type (Base_T)
 334         or else Is_Class_Wide_Type (Base_T)
 335       then
 336          return;
 337       end if;
 338
 339       --  Ada 2005 (AI-345): For synchronized types generate reference to the
 340       --  wrapper that allow us to dispatch calls through their implemented
 341       --  abstract interface types.
 342
 343       --  The check for Present here is to protect against previously reported
 344       --  critical errors.
 345
 346       Prim_List := Primitive_Operations (Base_T);
 347
 348       if No (Prim_List) then
 349          return;
 350       end if;
 351
 352       Prim := First_Elmt (Prim_List);
 353       while Present (Prim) loop
 354
 355          --  If the operation is derived, get the original for cross-reference
 356          --  reference purposes (it is the original for which we want the xref
 357          --  and for which the comes_from_source test must be performed).
 358
 359          Generate_Reference
 360            (Typ, Ultimate_Alias (Node (Prim)), 'p', Set_Ref => False);
 361          Next_Elmt (Prim);
 362       end loop;
 363    end Generate_Prim_Op_References;
 364
 365    ------------------------
 366    -- Generate_Reference --
 367    ------------------------
 368
 369    procedure Generate_Reference
 370      (E       : Entity_Id;
 371       N       : Node_Id;
 372       Typ     : Character := 'r';
 373       Set_Ref : Boolean   := True;
 374       Force   : Boolean   := False)
 375    is
 376       Actual_Typ     : Character := Typ;
 377       Call           : Node_Id;
 378       Def            : Source_Ptr;
 379       Ent            : Entity_Id;
 380       Ent_Scope      : Entity_Id;
 381       Formal         : Entity_Id;
 382       Kind           : Entity_Kind;
 383       Nod            : Node_Id;
 384       Ref            : Source_Ptr;
 385       Ref_Scope      : Entity_Id;
 386
 387       function Get_Through_Renamings (E : Entity_Id) return Entity_Id;
 388       --  Get the enclosing entity through renamings, which may come from
 389       --  source or from the translation of generic instantiations.
 390
 391       function Is_On_LHS (Node : Node_Id) return Boolean;
 392       --  Used to check if a node is on the left hand side of an assignment.
 393       --  The following cases are handled:
 394       --
 395       --   Variable    Node is a direct descendant of left hand side of an
 396       --               assignment statement.
 397       --
 398       --   Prefix      Of an indexed or selected component that is present in
 399       --               a subtree rooted by an assignment statement. There is
 400       --               no restriction of nesting of components, thus cases
 401       --               such as A.B (C).D are handled properly. However a prefix
 402       --               of a dereference (either implicit or explicit) is never
 403       --               considered as on a LHS.
 404       --
 405       --   Out param   Same as above cases, but OUT parameter
 406
 407       function OK_To_Set_Referenced return Boolean;
 408       --  Returns True if the Referenced flag can be set. There are a few
 409       --  exceptions where we do not want to set this flag, see body for
 410       --  details of these exceptional cases.
 411
 412       ---------------------------
 413       -- Get_Through_Renamings --
 414       ---------------------------
 415
 416       function Get_Through_Renamings (E : Entity_Id) return Entity_Id is
 417          Result : Entity_Id := E;
 418       begin
 419          while Present (Result)
 420            and then Is_Object (Result)
 421            and then Present (Renamed_Object (Result))
 422          loop
 423             Result := Get_Enclosing_Object (Renamed_Object (Result));
 424          end loop;
 425          return Result;
 426       end Get_Through_Renamings;
 427
 428       ---------------
 429       -- Is_On_LHS --
 430       ---------------
 431
 432       --  ??? There are several routines here and there that perform a similar
 433       --      (but subtly different) computation, which should be factored:
 434
 435       --      Sem_Util.May_Be_Lvalue
 436       --      Sem_Util.Known_To_Be_Assigned
 437       --      Exp_Ch2.Expand_Entry_Parameter.In_Assignment_Context
 438       --      Exp_Smem.Is_Out_Actual
 439
 440       function Is_On_LHS (Node : Node_Id) return Boolean is
 441          N : Node_Id;
 442          P : Node_Id;
 443          K : Node_Kind;
 444
 445       begin
 446          --  Only identifiers are considered, is this necessary???
 447
 448          if Nkind (Node) /= N_Identifier then
 449             return False;
 450          end if;
 451
 452          --  Immediate return if appeared as OUT parameter
 453
 454          if Kind = E_Out_Parameter then
 455             return True;
 456          end if;
 457
 458          --  Search for assignment statement subtree root
 459
 460          N := Node;
 461          loop
 462             P := Parent (N);
 463             K := Nkind (P);
 464
 465             if K = N_Assignment_Statement then
 466                return Name (P) = N;
 467
 468             --  Check whether the parent is a component and the current node is
 469             --  its prefix, but return False if the current node has an access
 470             --  type, as in that case the selected or indexed component is an
 471             --  implicit dereference, and the LHS is the designated object, not
 472             --  the access object.
 473
 474             --  ??? case of a slice assignment?
 475
 476             --  ??? Note that in some cases this is called too early
 477             --  (see comments in Sem_Ch8.Find_Direct_Name), at a point where
 478             --  the tree is not fully typed yet. In that case we may lack
 479             --  an Etype for N, and we must disable the check for an implicit
 480             --  dereference. If the dereference is on an LHS, this causes a
 481             --  false positive.
 482
 483             elsif (K = N_Selected_Component or else K = N_Indexed_Component)
 484               and then Prefix (P) = N
 485               and then not (Present (Etype (N))
 486                               and then
 487                             Is_Access_Type (Etype (N)))
 488             then
 489                N := P;
 490
 491             --  All other cases, definitely not on left side
 492
 493             else
 494                return False;
 495             end if;
 496          end loop;
 497       end Is_On_LHS;
 498
 499       ---------------------------
 500       -- OK_To_Set_Referenced --
 501       ---------------------------
 502
 503       function OK_To_Set_Referenced return Boolean is
 504          P : Node_Id;
 505
 506       begin
 507          --  A reference from a pragma Unreferenced or pragma Unmodified or
 508          --  pragma Warnings does not cause the Referenced flag to be set.
 509          --  This avoids silly warnings about things being referenced and
 510          --  not assigned when the only reference is from the pragma.
 511
 512          if Nkind (N) = N_Identifier then
 513             P := Parent (N);
 514
 515             if Nkind (P) = N_Pragma_Argument_Association then
 516                P := Parent (P);
 517
 518                if Nkind (P) = N_Pragma then
 519                   if Pragma_Name (P) = Name_Warnings
 520                        or else
 521                      Pragma_Name (P) = Name_Unmodified
 522                        or else
 523                      Pragma_Name (P) = Name_Unreferenced
 524                   then
 525                      return False;
 526                   end if;
 527                end if;
 528
 529             --  A reference to a formal in a named parameter association does
 530             --  not make the formal referenced. Formals that are unused in the
 531             --  subprogram body are properly flagged as such, even if calls
 532             --  elsewhere use named notation.
 533
 534             elsif Nkind (P) = N_Parameter_Association
 535               and then N = Selector_Name (P)
 536             then
 537                return False;
 538             end if;
 539          end if;
 540
 541          return True;
 542       end OK_To_Set_Referenced;
 543
 544    --  Start of processing for Generate_Reference
 545
 546    begin
 547       pragma Assert (Nkind (E) in N_Entity);
 548       Find_Actual (N, Formal, Call);
 549
 550       if Present (Formal) then
 551          Kind := Ekind (Formal);
 552       else
 553          Kind := E_Void;
 554       end if;
 555
 556       --  Check for obsolescent reference to package ASCII. GNAT treats this
 557       --  element of annex J specially since in practice, programs make a lot
 558       --  of use of this feature, so we don't include it in the set of features
 559       --  diagnosed when Warn_On_Obsolescent_Features mode is set. However we
 560       --  are required to note it as a violation of the RM defined restriction.
 561
 562       if E = Standard_ASCII then
 563          Check_Restriction (No_Obsolescent_Features, N);
 564       end if;
 565
 566       --  Check for reference to entity marked with Is_Obsolescent
 567
 568       --  Note that we always allow obsolescent references in the compiler
 569       --  itself and the run time, since we assume that we know what we are
 570       --  doing in such cases. For example the calls in Ada.Characters.Handling
 571       --  to its own obsolescent subprograms are just fine.
 572
 573       --  In any case we only generate warnings if we are in the extended main
 574       --  source unit, and the entity itself is not in the extended main source
 575       --  unit, since we assume the source unit itself knows what is going on
 576       --  (and for sure we do not want silly warnings, e.g. on the end line of
 577       --  an obsolescent procedure body).
 578
 579       if Is_Obsolescent (E)
 580         and then not GNAT_Mode
 581         and then not In_Extended_Main_Source_Unit (E)
 582         and then In_Extended_Main_Source_Unit (N)
 583       then
 584          Check_Restriction (No_Obsolescent_Features, N);
 585
 586          if Warn_On_Obsolescent_Feature then
 587             Output_Obsolescent_Entity_Warnings (N, E);
 588          end if;
 589       end if;
 590
 591       --  Warn if reference to Ada 2005 entity not in Ada 2005 mode. We only
 592       --  detect real explicit references (modifications and references).
 593
 594       if Comes_From_Source (N)
 595         and then Is_Ada_2005_Only (E)
 596         and then Ada_Version < Ada_2005
 597         and then Warn_On_Ada_2005_Compatibility
 598         and then (Typ = 'm' or else Typ = 'r' or else Typ = 's')
 599       then
 600          Error_Msg_NE ("& is only defined in Ada 2005?y?", N, E);
 601       end if;
 602
 603       --  Warn if reference to Ada 2012 entity not in Ada 2012 mode. We only
 604       --  detect real explicit references (modifications and references).
 605
 606       if Comes_From_Source (N)
 607         and then Is_Ada_2012_Only (E)
 608         and then Ada_Version < Ada_2012
 609         and then Warn_On_Ada_2012_Compatibility
 610         and then (Typ = 'm' or else Typ = 'r')
 611       then
 612          Error_Msg_NE ("& is only defined in Ada 2012?y?", N, E);
 613       end if;
 614
 615       --  Never collect references if not in main source unit. However, we omit
 616       --  this test if Typ is 'e' or 'k', since these entries are structural,
 617       --  and it is useful to have them in units that reference packages as
 618       --  well as units that define packages. We also omit the test for the
 619       --  case of 'p' since we want to include inherited primitive operations
 620       --  from other packages.
 621
 622       --  We also omit this test is this is a body reference for a subprogram
 623       --  instantiation. In this case the reference is to the generic body,
 624       --  which clearly need not be in the main unit containing the instance.
 625       --  For the same reason we accept an implicit reference generated for
 626       --  a default in an instance.
 627
 628       if not In_Extended_Main_Source_Unit (N) then
 629          if Typ = 'e'
 630            or else Typ = 'I'
 631            or else Typ = 'p'
 632            or else Typ = 'i'
 633            or else Typ = 'k'
 634            or else (Typ = 'b' and then Is_Generic_Instance (E))
 635
 636             --  Allow the generation of references to reads, writes and calls
 637             --  in Alfa mode when the related context comes from an instance.
 638
 639            or else
 640              (Alfa_Mode
 641                 and then In_Extended_Main_Code_Unit (N)
 642                 and then (Typ = 'm' or else Typ = 'r' or else Typ = 's'))
 643          then
 644             null;
 645          else
 646             return;
 647          end if;
 648       end if;
 649
 650       --  For reference type p, the entity must be in main source unit
 651
 652       if Typ = 'p' and then not In_Extended_Main_Source_Unit (E) then
 653          return;
 654       end if;
 655
 656       --  Unless the reference is forced, we ignore references where the
 657       --  reference itself does not come from source.
 658
 659       if not Force and then not Comes_From_Source (N) then
 660          return;
 661       end if;
 662
 663       --  Deal with setting entity as referenced, unless suppressed. Note that
 664       --  we still do Set_Referenced on entities that do not come from source.
 665       --  This situation arises when we have a source reference to a derived
 666       --  operation, where the derived operation itself does not come from
 667       --  source, but we still want to mark it as referenced, since we really
 668       --  are referencing an entity in the corresponding package (this avoids
 669       --  wrong complaints that the package contains no referenced entities).
 670
 671       if Set_Ref then
 672
 673          --  Assignable object appearing on left side of assignment or as
 674          --  an out parameter.
 675
 676          if Is_Assignable (E)
 677            and then Is_On_LHS (N)
 678            and then Ekind (E) /= E_In_Out_Parameter
 679          then
 680             --  For objects that are renamings, just set as simply referenced
 681             --  we do not try to do assignment type tracking in this case.
 682
 683             if Present (Renamed_Object (E)) then
 684                Set_Referenced (E);
 685
 686             --  Out parameter case
 687
 688             elsif Kind = E_Out_Parameter then
 689
 690                --  If warning mode for all out parameters is set, or this is
 691                --  the only warning parameter, then we want to mark this for
 692                --  later warning logic by setting Referenced_As_Out_Parameter
 693
 694                if Warn_On_Modified_As_Out_Parameter (Formal) then
 695                   Set_Referenced_As_Out_Parameter (E, True);
 696                   Set_Referenced_As_LHS (E, False);
 697
 698                --  For OUT parameter not covered by the above cases, we simply
 699                --  regard it as a normal reference (in this case we do not
 700                --  want any of the warning machinery for out parameters).
 701
 702                else
 703                   Set_Referenced (E);
 704                end if;
 705
 706             --  For the left hand of an assignment case, we do nothing here.
 707             --  The processing for Analyze_Assignment_Statement will set the
 708             --  Referenced_As_LHS flag.
 709
 710             else
 711                null;
 712             end if;
 713
 714          --  Check for a reference in a pragma that should not count as a
 715          --  making the variable referenced for warning purposes.
 716
 717          elsif Is_Non_Significant_Pragma_Reference (N) then
 718             null;
 719
 720          --  A reference in an attribute definition clause does not count as a
 721          --  reference except for the case of Address. The reason that 'Address
 722          --  is an exception is that it creates an alias through which the
 723          --  variable may be referenced.
 724
 725          elsif Nkind (Parent (N)) = N_Attribute_Definition_Clause
 726            and then Chars (Parent (N)) /= Name_Address
 727            and then N = Name (Parent (N))
 728          then
 729             null;
 730
 731          --  Constant completion does not count as a reference
 732
 733          elsif Typ = 'c'
 734            and then Ekind (E) = E_Constant
 735          then
 736             null;
 737
 738          --  Record representation clause does not count as a reference
 739
 740          elsif Nkind (N) = N_Identifier
 741            and then Nkind (Parent (N)) = N_Record_Representation_Clause
 742          then
 743             null;
 744
 745          --  Discriminants do not need to produce a reference to record type
 746
 747          elsif Typ = 'd'
 748            and then Nkind (Parent (N)) = N_Discriminant_Specification
 749          then
 750             null;
 751
 752          --  All other cases
 753
 754          else
 755             --  Special processing for IN OUT parameters, where we have an
 756             --  implicit assignment to a simple variable.
 757
 758             if Kind = E_In_Out_Parameter
 759               and then Is_Assignable (E)
 760             then
 761                --  For sure this counts as a normal read reference
 762
 763                Set_Referenced (E);
 764                Set_Last_Assignment (E, Empty);
 765
 766                --  We count it as being referenced as an out parameter if the
 767                --  option is set to warn on all out parameters, except that we
 768                --  have a special exclusion for an intrinsic subprogram, which
 769                --  is most likely an instantiation of Unchecked_Deallocation
 770                --  which we do not want to consider as an assignment since it
 771                --  generates false positives. We also exclude the case of an
 772                --  IN OUT parameter if the name of the procedure is Free,
 773                --  since we suspect similar semantics.
 774
 775                if Warn_On_All_Unread_Out_Parameters
 776                  and then Is_Entity_Name (Name (Call))
 777                  and then not Is_Intrinsic_Subprogram (Entity (Name (Call)))
 778                  and then Chars (Name (Call)) /= Name_Free
 779                then
 780                   Set_Referenced_As_Out_Parameter (E, True);
 781                   Set_Referenced_As_LHS (E, False);
 782                end if;
 783
 784             --  Don't count a recursive reference within a subprogram as a
 785             --  reference (that allows detection of a recursive subprogram
 786             --  whose only references are recursive calls as unreferenced).
 787
 788             elsif Is_Subprogram (E)
 789               and then E = Nearest_Dynamic_Scope (Current_Scope)
 790             then
 791                null;
 792
 793             --  Any other occurrence counts as referencing the entity
 794
 795             elsif OK_To_Set_Referenced then
 796                Set_Referenced (E);
 797
 798                --  If variable, this is an OK reference after an assignment
 799                --  so we can clear the Last_Assignment indication.
 800
 801                if Is_Assignable (E) then
 802                   Set_Last_Assignment (E, Empty);
 803                end if;
 804             end if;
 805          end if;
 806
 807          --  Check for pragma Unreferenced given and reference is within
 808          --  this source unit (occasion for possible warning to be issued).
 809
 810          if Has_Unreferenced (E)
 811            and then In_Same_Extended_Unit (E, N)
 812          then
 813             --  A reference as a named parameter in a call does not count
 814             --  as a violation of pragma Unreferenced for this purpose...
 815
 816             if Nkind (N) = N_Identifier
 817               and then Nkind (Parent (N)) = N_Parameter_Association
 818               and then Selector_Name (Parent (N)) = N
 819             then
 820                null;
 821
 822             --  ... Neither does a reference to a variable on the left side
 823             --  of an assignment.
 824
 825             elsif Is_On_LHS (N) then
 826                null;
 827
 828             --  For entry formals, we want to place the warning message on the
 829             --  corresponding entity in the accept statement. The current scope
 830             --  is the body of the accept, so we find the formal whose name
 831             --  matches that of the entry formal (there is no link between the
 832             --  two entities, and the one in the accept statement is only used
 833             --  for conformance checking).
 834
 835             elsif Ekind (Scope (E)) = E_Entry then
 836                declare
 837                   BE : Entity_Id;
 838
 839                begin
 840                   BE := First_Entity (Current_Scope);
 841                   while Present (BE) loop
 842                      if Chars (BE) = Chars (E) then
 843                         Error_Msg_NE -- CODEFIX
 844                           ("??pragma Unreferenced given for&!", N, BE);
 845                         exit;
 846                      end if;
 847
 848                      Next_Entity (BE);
 849                   end loop;
 850                end;
 851
 852             --  Here we issue the warning, since this is a real reference
 853
 854             else
 855                Error_Msg_NE -- CODEFIX
 856                  ("?pragma Unreferenced given for&!", N, E);
 857             end if;
 858          end if;
 859
 860          --  If this is a subprogram instance, mark as well the internal
 861          --  subprogram in the wrapper package, which may be a visible
 862          --  compilation unit.
 863
 864          if Is_Overloadable (E)
 865            and then Is_Generic_Instance (E)
 866            and then Present (Alias (E))
 867          then
 868             Set_Referenced (Alias (E));
 869          end if;
 870       end if;
 871
 872       --  Generate reference if all conditions are met:
 873
 874       if
 875          --  Cross referencing must be active
 876
 877          Opt.Xref_Active
 878
 879          --  The entity must be one for which we collect references
 880
 881          and then Xref_Entity_Letters (Ekind (E)) /= ' '
 882
 883          --  Both Sloc values must be set to something sensible
 884
 885          and then Sloc (E) > No_Location
 886          and then Sloc (N) > No_Location
 887
 888          --  Ignore references from within an instance. The only exceptions to
 889          --  this are default subprograms, for which we generate an implicit
 890          --  reference and compilations in Alfa_Mode.
 891
 892          and then
 893            (Instantiation_Location (Sloc (N)) = No_Location
 894              or else Typ = 'i'
 895              or else Alfa_Mode)
 896
 897         --  Ignore dummy references
 898
 899         and then Typ /= ' '
 900       then
 901          if Nkind_In (N, N_Identifier,
 902                          N_Defining_Identifier,
 903                          N_Defining_Operator_Symbol,
 904                          N_Operator_Symbol,
 905                          N_Defining_Character_Literal)
 906            or else Nkind (N) in N_Op
 907            or else (Nkind (N) = N_Character_Literal
 908                      and then Sloc (Entity (N)) /= Standard_Location)
 909          then
 910             Nod := N;
 911
 912          elsif Nkind_In (N, N_Expanded_Name, N_Selected_Component) then
 913             Nod := Selector_Name (N);
 914
 915          else
 916             return;
 917          end if;
 918
 919          --  Normal case of source entity comes from source
 920
 921          if Comes_From_Source (E) then
 922             Ent := E;
 923
 924          --  Entity does not come from source, but is a derived subprogram and
 925          --  the derived subprogram comes from source (after one or more
 926          --  derivations) in which case the reference is to parent subprogram.
 927
 928          elsif Is_Overloadable (E)
 929            and then Present (Alias (E))
 930          then
 931             Ent := Alias (E);
 932             while not Comes_From_Source (Ent) loop
 933                if No (Alias (Ent)) then
 934                   return;
 935                end if;
 936
 937                Ent := Alias (Ent);
 938             end loop;
 939
 940          --  The internally created defining entity for a child subprogram
 941          --  that has no previous spec has valid references.
 942
 943          elsif Is_Overloadable (E)
 944            and then Is_Child_Unit (E)
 945          then
 946             Ent := E;
 947
 948          --  Ditto for the formals of such a subprogram
 949
 950          elsif Is_Overloadable (Scope (E))
 951            and then Is_Child_Unit (Scope (E))
 952          then
 953             Ent := E;
 954
 955          --  Record components of discriminated subtypes or derived types must
 956          --  be treated as references to the original component.
 957
 958          elsif Ekind (E) = E_Component
 959            and then Comes_From_Source (Original_Record_Component (E))
 960          then
 961             Ent := Original_Record_Component (E);
 962
 963          --  If this is an expanded reference to a discriminant, recover the
 964          --  original discriminant, which gets the reference.
 965
 966          elsif Ekind (E) = E_In_Parameter
 967            and then  Present (Discriminal_Link (E))
 968          then
 969             Ent := Discriminal_Link (E);
 970             Set_Referenced (Ent);
 971
 972          --  Ignore reference to any other entity that is not from source
 973
 974          else
 975             return;
 976          end if;
 977
 978          --  In Alfa mode, consider the underlying entity renamed instead of
 979          --  the renaming, which is needed to compute a valid set of effects
 980          --  (reads, writes) for the enclosing subprogram.
 981
 982          if Alfa_Mode then
 983             Ent := Get_Through_Renamings (Ent);
 984
 985             --  If no enclosing object, then it could be a reference to any
 986             --  location not tracked individually, like heap-allocated data.
 987             --  Conservatively approximate this possibility by generating a
 988             --  dereference, and return.
 989
 990             if No (Ent) then
 991                if Actual_Typ = 'w' then
 992                   Alfa.Generate_Dereference (Nod, 'r');
 993                   Alfa.Generate_Dereference (Nod, 'w');
 994                else
 995                   Alfa.Generate_Dereference (Nod, 'r');
 996                end if;
 997
 998                return;
 999             end if;
1000          end if;
1001
1002          --  Record reference to entity
1003
1004          if Actual_Typ = 'p'
1005            and then Is_Subprogram (Nod)
1006            and then Present (Overridden_Operation (Nod))
1007          then
1008             Actual_Typ := 'P';
1009          end if;
1010
1011          if Alfa_Mode then
1012             Ref := Sloc (Nod);
1013             Def := Sloc (Ent);
1014
1015             Ref_Scope := Alfa.Enclosing_Subprogram_Or_Package (Nod);
1016             Ent_Scope := Alfa.Enclosing_Subprogram_Or_Package (Ent);
1017
1018             --  Since we are reaching through renamings in Alfa mode, we may
1019             --  end up with standard constants. Ignore those.
1020
1021             if Sloc (Ent_Scope) <= Standard_Location
1022               or else Def <= Standard_Location
1023             then
1024                return;
1025             end if;
1026
1027             Add_Entry
1028               ((Ent      => Ent,
1029                 Loc       => Ref,
1030                 Typ       => Actual_Typ,
1031                 Eun       => Get_Code_Unit (Def),
1032                 Lun       => Get_Code_Unit (Ref),
1033                 Ref_Scope => Ref_Scope,
1034                 Ent_Scope => Ent_Scope),
1035                Ent_Scope_File => Get_Code_Unit (Ent));
1036
1037          else
1038             Ref := Original_Location (Sloc (Nod));
1039             Def := Original_Location (Sloc (Ent));
1040
1041             --  If this is an operator symbol, skip the initial quote for
1042             --  navigation purposes. This is not done for the end label,
1043             --  where we want the actual position after the closing quote.
1044
1045             if Typ = 't' then
1046                null;
1047
1048             elsif Nkind (N) = N_Defining_Operator_Symbol
1049               or else Nkind (Nod) = N_Operator_Symbol
1050             then
1051                Ref := Ref + 1;
1052             end if;
1053
1054             Add_Entry
1055               ((Ent      => Ent,
1056                 Loc       => Ref,
1057                 Typ       => Actual_Typ,
1058                 Eun       => Get_Source_Unit (Def),
1059                 Lun       => Get_Source_Unit (Ref),
1060                 Ref_Scope => Empty,
1061                 Ent_Scope => Empty),
1062                Ent_Scope_File => No_Unit);
1063          end if;
1064       end if;
1065    end Generate_Reference;
1066
1067    -----------------------------------
1068    -- Generate_Reference_To_Formals --
1069    -----------------------------------
1070
1071    procedure Generate_Reference_To_Formals (E : Entity_Id) is
1072       Formal : Entity_Id;
1073
1074    begin
1075       if Is_Generic_Subprogram (E) then
1076          Formal := First_Entity (E);
1077
1078          while Present (Formal)
1079            and then not Is_Formal (Formal)
1080          loop
1081             Next_Entity (Formal);
1082          end loop;
1083
1084       else
1085          Formal := First_Formal (E);
1086       end if;
1087
1088       while Present (Formal) loop
1089          if Ekind (Formal) = E_In_Parameter then
1090
1091             if Nkind (Parameter_Type (Parent (Formal)))
1092               = N_Access_Definition
1093             then
1094                Generate_Reference (E, Formal, '^', False);
1095             else
1096                Generate_Reference (E, Formal, '>', False);
1097             end if;
1098
1099          elsif Ekind (Formal) = E_In_Out_Parameter then
1100             Generate_Reference (E, Formal, '=', False);
1101
1102          else
1103             Generate_Reference (E, Formal, '<', False);
1104          end if;
1105
1106          Next_Formal (Formal);
1107       end loop;
1108    end Generate_Reference_To_Formals;
1109
1110    -------------------------------------------
1111    -- Generate_Reference_To_Generic_Formals --
1112    -------------------------------------------
1113
1114    procedure Generate_Reference_To_Generic_Formals (E : Entity_Id) is
1115       Formal : Entity_Id;
1116
1117    begin
1118       Formal := First_Entity (E);
1119       while Present (Formal) loop
1120          if Comes_From_Source (Formal) then
1121             Generate_Reference (E, Formal, 'z', False);
1122          end if;
1123
1124          Next_Entity (Formal);
1125       end loop;
1126    end Generate_Reference_To_Generic_Formals;
1127
1128    -------------
1129    -- Get_Key --
1130    -------------
1131
1132    function Get_Key (E : Xref_Entry_Number) return Xref_Entry_Number is
1133    begin
1134       return E;
1135    end Get_Key;
1136
1137    ----------
1138    -- Hash --
1139    ----------
1140
1141    function Hash (F : Xref_Entry_Number) return Header_Num is
1142       --  It is unlikely to have two references to the same entity at the same
1143       --  source location, so the hash function depends only on the Ent and Loc
1144       --  fields.
1145
1146       XE : Xref_Entry renames Xrefs.Table (F);
1147       type M is mod 2**32;
1148
1149       H : constant M := M (XE.Key.Ent) + 2 ** 7 * M (abs XE.Key.Loc);
1150       --  It would be more natural to write:
1151       --
1152       --    H : constant M := M'Mod (XE.Key.Ent) + 2**7 * M'Mod (XE.Key.Loc);
1153       --
1154       --  But we can't use M'Mod, because it prevents bootstrapping with older
1155       --  compilers. Loc can be negative, so we do "abs" before converting.
1156       --  One day this can be cleaned up ???
1157
1158    begin
1159       return Header_Num (H mod Num_Buckets);
1160    end Hash;
1161
1162    -----------------
1163    -- HT_Set_Next --
1164    -----------------
1165
1166    procedure HT_Set_Next (E : Xref_Entry_Number; Next : Xref_Entry_Number) is
1167    begin
1168       Xrefs.Table (E).HTable_Next := Next;
1169    end HT_Set_Next;
1170
1171    -------------
1172    -- HT_Next --
1173    -------------
1174
1175    function HT_Next (E : Xref_Entry_Number) return Xref_Entry_Number is
1176    begin
1177       return Xrefs.Table (E).HTable_Next;
1178    end HT_Next;
1179
1180    ----------------
1181    -- Initialize --
1182    ----------------
1183
1184    procedure Initialize is
1185    begin
1186       Xrefs.Init;
1187    end Initialize;
1188
1189    --------
1190    -- Lt --
1191    --------
1192
1193    function Lt (T1, T2 : Xref_Entry) return Boolean is
1194    begin
1195       --  First test: if entity is in different unit, sort by unit
1196
1197       if T1.Key.Eun /= T2.Key.Eun then
1198          return Dependency_Num (T1.Key.Eun) < Dependency_Num (T2.Key.Eun);
1199
1200       --  Second test: within same unit, sort by entity Sloc
1201
1202       elsif T1.Def /= T2.Def then
1203          return T1.Def < T2.Def;
1204
1205       --  Third test: sort definitions ahead of references
1206
1207       elsif T1.Key.Loc = No_Location then
1208          return True;
1209
1210       elsif T2.Key.Loc = No_Location then
1211          return False;
1212
1213       --  Fourth test: for same entity, sort by reference location unit
1214
1215       elsif T1.Key.Lun /= T2.Key.Lun then
1216          return Dependency_Num (T1.Key.Lun) < Dependency_Num (T2.Key.Lun);
1217
1218       --  Fifth test: order of location within referencing unit
1219
1220       elsif T1.Key.Loc /= T2.Key.Loc then
1221          return T1.Key.Loc < T2.Key.Loc;
1222
1223       --  Finally, for two locations at the same address, we prefer
1224       --  the one that does NOT have the type 'r' so that a modification
1225       --  or extension takes preference, when there are more than one
1226       --  reference at the same location. As a result, in the case of
1227       --  entities that are in-out actuals, the read reference follows
1228       --  the modify reference.
1229
1230       else
1231          return T2.Key.Typ = 'r';
1232       end if;
1233    end Lt;
1234
1235    -----------------------
1236    -- Output_References --
1237    -----------------------
1238
1239    procedure Output_References is
1240
1241       procedure Get_Type_Reference
1242         (Ent   : Entity_Id;
1243          Tref  : out Entity_Id;
1244          Left  : out Character;
1245          Right : out Character);
1246       --  Given an Entity_Id Ent, determines whether a type reference is
1247       --  required. If so, Tref is set to the entity for the type reference
1248       --  and Left and Right are set to the left/right brackets to be output
1249       --  for the reference. If no type reference is required, then Tref is
1250       --  set to Empty, and Left/Right are set to space.
1251
1252       procedure Output_Import_Export_Info (Ent : Entity_Id);
1253       --  Output language and external name information for an interfaced
1254       --  entity, using the format <language, external_name>.
1255
1256       ------------------------
1257       -- Get_Type_Reference --
1258       ------------------------
1259
1260       procedure Get_Type_Reference
1261         (Ent   : Entity_Id;
1262          Tref  : out Entity_Id;
1263          Left  : out Character;
1264          Right : out Character)
1265       is
1266          Sav : Entity_Id;
1267
1268       begin
1269          --  See if we have a type reference
1270
1271          Tref := Ent;
1272          Left := '{';
1273          Right := '}';
1274
1275          loop
1276             Sav := Tref;
1277
1278             --  Processing for types
1279
1280             if Is_Type (Tref) then
1281
1282                --  Case of base type
1283
1284                if Base_Type (Tref) = Tref then
1285
1286                   --  If derived, then get first subtype
1287
1288                   if Tref /= Etype (Tref) then
1289                      Tref := First_Subtype (Etype (Tref));
1290
1291                      --  Set brackets for derived type, but don't override
1292                      --  pointer case since the fact that something is a
1293                      --  pointer is more important.
1294
1295                      if Left /= '(' then
1296                         Left := '<';
1297                         Right := '>';
1298                      end if;
1299
1300                   --  If non-derived ptr, get directly designated type.
1301                   --  If the type has a full view, all references are on the
1302                   --  partial view, that is seen first.
1303
1304                   elsif Is_Access_Type (Tref) then
1305                      Tref := Directly_Designated_Type (Tref);
1306                      Left := '(';
1307                      Right := ')';
1308
1309                   elsif Is_Private_Type (Tref)
1310                     and then Present (Full_View (Tref))
1311                   then
1312                      if Is_Access_Type (Full_View (Tref)) then
1313                         Tref := Directly_Designated_Type (Full_View (Tref));
1314                         Left := '(';
1315                         Right := ')';
1316
1317                      --  If the full view is an array type, we also retrieve
1318                      --  the corresponding component type, because the ali
1319                      --  entry already indicates that this is an array.
1320
1321                      elsif Is_Array_Type (Full_View (Tref)) then
1322                         Tref := Component_Type (Full_View (Tref));
1323                         Left := '(';
1324                         Right := ')';
1325                      end if;
1326
1327                   --  If non-derived array, get component type. Skip component
1328                   --  type for case of String or Wide_String, saves worthwhile
1329                   --  space.
1330
1331                   elsif Is_Array_Type (Tref)
1332                     and then Tref /= Standard_String
1333                     and then Tref /= Standard_Wide_String
1334                   then
1335                      Tref := Component_Type (Tref);
1336                      Left := '(';
1337                      Right := ')';
1338
1339                   --  For other non-derived base types, nothing
1340
1341                   else
1342                      exit;
1343                   end if;
1344
1345                --  For a subtype, go to ancestor subtype
1346
1347                else
1348                   Tref := Ancestor_Subtype (Tref);
1349
1350                   --  If no ancestor subtype, go to base type
1351
1352                   if No (Tref) then
1353                      Tref := Base_Type (Sav);
1354                   end if;
1355                end if;
1356
1357             --  For objects, functions, enum literals, just get type from
1358             --  Etype field.
1359
1360             elsif Is_Object (Tref)
1361               or else Ekind (Tref) = E_Enumeration_Literal
1362               or else Ekind (Tref) = E_Function
1363               or else Ekind (Tref) = E_Operator
1364             then
1365                Tref := Etype (Tref);
1366
1367                --  Another special case: an object of a classwide type
1368                --  initialized with a tag-indeterminate call gets a subtype
1369                --  of the classwide type during expansion. See if the original
1370                --  type in the declaration is named, and return it instead
1371                --  of going to the root type.
1372
1373                if Ekind (Tref) = E_Class_Wide_Subtype
1374                  and then Nkind (Parent (Ent)) = N_Object_Declaration
1375                  and then
1376                    Nkind (Original_Node (Object_Definition (Parent (Ent))))
1377                      = N_Identifier
1378                then
1379                   Tref :=
1380                     Entity
1381                       (Original_Node ((Object_Definition (Parent (Ent)))));
1382                end if;
1383
1384             --  For anything else, exit
1385
1386             else
1387                exit;
1388             end if;
1389
1390             --  Exit if no type reference, or we are stuck in some loop trying
1391             --  to find the type reference, or if the type is standard void
1392             --  type (the latter is an implementation artifact that should not
1393             --  show up in the generated cross-references).
1394
1395             exit when No (Tref)
1396               or else Tref = Sav
1397               or else Tref = Standard_Void_Type;
1398
1399             --  If we have a usable type reference, return, otherwise keep
1400             --  looking for something useful (we are looking for something
1401             --  that either comes from source or standard)
1402
1403             if Sloc (Tref) = Standard_Location
1404               or else Comes_From_Source (Tref)
1405             then
1406                --  If the reference is a subtype created for a generic actual,
1407                --  go actual directly, the inner subtype is not user visible.
1408
1409                if Nkind (Parent (Tref)) = N_Subtype_Declaration
1410                  and then not Comes_From_Source (Parent (Tref))
1411                  and then
1412                   (Is_Wrapper_Package (Scope (Tref))
1413                      or else Is_Generic_Instance (Scope (Tref)))
1414                then
1415                   Tref := First_Subtype (Base_Type (Tref));
1416                end if;
1417
1418                return;
1419             end if;
1420          end loop;
1421
1422          --  If we fall through the loop, no type reference
1423
1424          Tref := Empty;
1425          Left := ' ';
1426          Right := ' ';
1427       end Get_Type_Reference;
1428
1429       -------------------------------
1430       -- Output_Import_Export_Info --
1431       -------------------------------
1432
1433       procedure Output_Import_Export_Info (Ent : Entity_Id) is
1434          Language_Name : Name_Id;
1435          Conv          : constant Convention_Id := Convention (Ent);
1436
1437       begin
1438          --  Generate language name from convention
1439
1440          if Conv  = Convention_C then
1441             Language_Name := Name_C;
1442
1443          elsif Conv = Convention_CPP then
1444             Language_Name := Name_CPP;
1445
1446          elsif Conv = Convention_Ada then
1447             Language_Name := Name_Ada;
1448
1449          else
1450             --  For the moment we ignore all other cases ???
1451
1452             return;
1453          end if;
1454
1455          Write_Info_Char ('<');
1456          Get_Unqualified_Name_String (Language_Name);
1457
1458          for J in 1 .. Name_Len loop
1459             Write_Info_Char (Name_Buffer (J));
1460          end loop;
1461
1462          if Present (Interface_Name (Ent)) then
1463             Write_Info_Char (',');
1464             String_To_Name_Buffer (Strval (Interface_Name (Ent)));
1465
1466             for J in 1 .. Name_Len loop
1467                Write_Info_Char (Name_Buffer (J));
1468             end loop;
1469          end if;
1470
1471          Write_Info_Char ('>');
1472       end Output_Import_Export_Info;
1473
1474    --  Start of processing for Output_References
1475
1476    begin
1477       --  First we add references to the primitive operations of tagged types
1478       --  declared in the main unit.
1479
1480       Handle_Prim_Ops : declare
1481          Ent  : Entity_Id;
1482
1483       begin
1484          for J in 1 .. Xrefs.Last loop
1485             Ent := Xrefs.Table (J).Key.Ent;
1486
1487             if Is_Type (Ent)
1488               and then Is_Tagged_Type (Ent)
1489               and then Is_Base_Type (Ent)
1490               and then In_Extended_Main_Source_Unit (Ent)
1491             then
1492                Generate_Prim_Op_References (Ent);
1493             end if;
1494          end loop;
1495       end Handle_Prim_Ops;
1496
1497       --  Before we go ahead and output the references we have a problem
1498       --  that needs dealing with. So far we have captured things that are
1499       --  definitely referenced by the main unit, or defined in the main
1500       --  unit. That's because we don't want to clutter up the ali file
1501       --  for this unit with definition lines for entities in other units
1502       --  that are not referenced.
1503
1504       --  But there is a glitch. We may reference an entity in another unit,
1505       --  and it may have a type reference to an entity that is not directly
1506       --  referenced in the main unit, which may mean that there is no xref
1507       --  entry for this entity yet in the list of references.
1508
1509       --  If we don't do something about this, we will end with an orphan type
1510       --  reference, i.e. it will point to an entity that does not appear
1511       --  within the generated references in the ali file. That is not good for
1512       --  tools using the xref information.
1513
1514       --  To fix this, we go through the references adding definition entries
1515       --  for any unreferenced entities that can be referenced in a type
1516       --  reference. There is a recursion problem here, and that is dealt with
1517       --  by making sure that this traversal also traverses any entries that
1518       --  get added by the traversal.
1519
1520       Handle_Orphan_Type_References : declare
1521          J    : Nat;
1522          Tref : Entity_Id;
1523          Ent  : Entity_Id;
1524
1525          L, R : Character;
1526          pragma Warnings (Off, L);
1527          pragma Warnings (Off, R);
1528
1529          procedure New_Entry (E : Entity_Id);
1530          --  Make an additional entry into the Xref table for a type entity
1531          --  that is related to the current entity (parent, type ancestor,
1532          --  progenitor, etc.).
1533
1534          ----------------
1535          -- New_Entry --
1536          ----------------
1537
1538          procedure New_Entry (E : Entity_Id) is
1539          begin
1540             pragma Assert (Present (E));
1541
1542             if not Has_Xref_Entry (Implementation_Base_Type (E))
1543               and then Sloc (E) > No_Location
1544             then
1545                Add_Entry
1546                  ((Ent => E,
1547                    Loc => No_Location,
1548                    Typ => Character'First,
1549                    Eun => Get_Source_Unit (Original_Location (Sloc (E))),
1550                    Lun => No_Unit,
1551                    Ref_Scope => Empty,
1552                    Ent_Scope => Empty),
1553                   Ent_Scope_File => No_Unit);
1554             end if;
1555          end New_Entry;
1556
1557       --  Start of processing for Handle_Orphan_Type_References
1558
1559       begin
1560          --  Note that this is not a for loop for a very good reason. The
1561          --  processing of items in the table can add new items to the table,
1562          --  and they must be processed as well.
1563
1564          J := 1;
1565          while J <= Xrefs.Last loop
1566             Ent := Xrefs.Table (J).Key.Ent;
1567             Get_Type_Reference (Ent, Tref, L, R);
1568
1569             if Present (Tref)
1570               and then not Has_Xref_Entry (Tref)
1571               and then Sloc (Tref) > No_Location
1572             then
1573                New_Entry (Tref);
1574
1575                if Is_Record_Type (Ent)
1576                  and then Present (Interfaces (Ent))
1577                then
1578                   --  Add an entry for each one of the given interfaces
1579                   --  implemented by type Ent.
1580
1581                   declare
1582                      Elmt : Elmt_Id := First_Elmt (Interfaces (Ent));
1583                   begin
1584                      while Present (Elmt) loop
1585                         New_Entry (Node (Elmt));
1586                         Next_Elmt (Elmt);
1587                      end loop;
1588                   end;
1589                end if;
1590             end if;
1591
1592             --  Collect inherited primitive operations that may be declared in
1593             --  another unit and have no visible reference in the current one.
1594
1595             if Is_Type (Ent)
1596               and then Is_Tagged_Type (Ent)
1597               and then Is_Derived_Type (Ent)
1598               and then Is_Base_Type (Ent)
1599               and then In_Extended_Main_Source_Unit (Ent)
1600             then
1601                declare
1602                   Op_List : constant Elist_Id := Primitive_Operations (Ent);
1603                   Op      : Elmt_Id;
1604                   Prim    : Entity_Id;
1605
1606                   function Parent_Op (E : Entity_Id) return Entity_Id;
1607                   --  Find original operation, which may be inherited through
1608                   --  several derivations.
1609
1610                   function Parent_Op (E : Entity_Id) return Entity_Id is
1611                      Orig_Op : constant Entity_Id := Alias (E);
1612
1613                   begin
1614                      if No (Orig_Op) then
1615                         return Empty;
1616
1617                      elsif not Comes_From_Source (E)
1618                        and then not Has_Xref_Entry (Orig_Op)
1619                        and then Comes_From_Source (Orig_Op)
1620                      then
1621                         return Orig_Op;
1622                      else
1623                         return Parent_Op (Orig_Op);
1624                      end if;
1625                   end Parent_Op;
1626
1627                begin
1628                   Op := First_Elmt (Op_List);
1629                   while Present (Op) loop
1630                      Prim := Parent_Op (Node (Op));
1631
1632                      if Present (Prim) then
1633                         Add_Entry
1634                           ((Ent => Prim,
1635                             Loc => No_Location,
1636                             Typ => Character'First,
1637                             Eun => Get_Source_Unit (Sloc (Prim)),
1638                             Lun => No_Unit,
1639                             Ref_Scope => Empty,
1640                             Ent_Scope => Empty),
1641                            Ent_Scope_File => No_Unit);
1642                      end if;
1643
1644                      Next_Elmt (Op);
1645                   end loop;
1646                end;
1647             end if;
1648
1649             J := J + 1;
1650          end loop;
1651       end Handle_Orphan_Type_References;
1652
1653       --  Now we have all the references, including those for any embedded
1654       --  type references, so we can sort them, and output them.
1655
1656       Output_Refs : declare
1657
1658          Nrefs : constant Nat := Xrefs.Last;
1659          --  Number of references in table
1660
1661          Rnums : array (0 .. Nrefs) of Nat;
1662          --  This array contains numbers of references in the Xrefs table.
1663          --  This list is sorted in output order. The extra 0'th entry is
1664          --  convenient for the call to sort. When we sort the table, we
1665          --  move the entries in Rnums around, but we do not move the
1666          --  original table entries.
1667
1668          Curxu : Unit_Number_Type;
1669          --  Current xref unit
1670
1671          Curru : Unit_Number_Type;
1672          --  Current reference unit for one entity
1673
1674          Curent : Entity_Id;
1675          --  Current entity
1676
1677          Curnam : String (1 .. Name_Buffer'Length);
1678          Curlen : Natural;
1679          --  Simple name and length of current entity
1680
1681          Curdef : Source_Ptr;
1682          --  Original source location for current entity
1683
1684          Crloc : Source_Ptr;
1685          --  Current reference location
1686
1687          Ctyp : Character;
1688          --  Entity type character
1689
1690          Prevt : Character;
1691          --  reference kind of previous reference
1692
1693          Tref : Entity_Id;
1694          --  Type reference
1695
1696          Rref : Node_Id;
1697          --  Renaming reference
1698
1699          Trunit : Unit_Number_Type;
1700          --  Unit number for type reference
1701
1702          function Lt (Op1, Op2 : Natural) return Boolean;
1703          --  Comparison function for Sort call
1704
1705          function Name_Change (X : Entity_Id) return Boolean;
1706          --  Determines if entity X has a different simple name from Curent
1707
1708          procedure Move (From : Natural; To : Natural);
1709          --  Move procedure for Sort call
1710
1711          package Sorting is new GNAT.Heap_Sort_G (Move, Lt);
1712
1713          --------
1714          -- Lt --
1715          --------
1716
1717          function Lt (Op1, Op2 : Natural) return Boolean is
1718             T1 : Xref_Entry renames Xrefs.Table (Rnums (Nat (Op1)));
1719             T2 : Xref_Entry renames Xrefs.Table (Rnums (Nat (Op2)));
1720
1721          begin
1722             return Lt (T1, T2);
1723          end Lt;
1724
1725          ----------
1726          -- Move --
1727          ----------
1728
1729          procedure Move (From : Natural; To : Natural) is
1730          begin
1731             Rnums (Nat (To)) := Rnums (Nat (From));
1732          end Move;
1733
1734          -----------------
1735          -- Name_Change --
1736          -----------------
1737
1738          --  Why a string comparison here??? Why not compare Name_Id values???
1739
1740          function Name_Change (X : Entity_Id) return Boolean is
1741          begin
1742             Get_Unqualified_Name_String (Chars (X));
1743
1744             if Name_Len /= Curlen then
1745                return True;
1746             else
1747                return Name_Buffer (1 .. Curlen) /= Curnam (1 .. Curlen);
1748             end if;
1749          end Name_Change;
1750
1751       --  Start of processing for Output_Refs
1752
1753       begin
1754          --  Capture the definition Sloc values. We delay doing this till now,
1755          --  since at the time the reference or definition is made, private
1756          --  types may be swapped, and the Sloc value may be incorrect. We
1757          --  also set up the pointer vector for the sort.
1758
1759          --  For user-defined operators we need to skip the initial quote and
1760          --  point to the first character of the name, for navigation purposes.
1761
1762          for J in 1 .. Nrefs loop
1763             declare
1764                E   : constant Entity_Id  := Xrefs.Table (J).Key.Ent;
1765                Loc : constant Source_Ptr := Original_Location (Sloc (E));
1766
1767             begin
1768                Rnums (J) := J;
1769
1770                if Nkind (E) = N_Defining_Operator_Symbol then
1771                   Xrefs.Table (J).Def := Loc + 1;
1772                else
1773                   Xrefs.Table (J).Def := Loc;
1774                end if;
1775             end;
1776          end loop;
1777
1778          --  Sort the references
1779
1780          Sorting.Sort (Integer (Nrefs));
1781
1782          --  Initialize loop through references
1783
1784          Curxu  := No_Unit;
1785          Curent := Empty;
1786          Curdef := No_Location;
1787          Curru  := No_Unit;
1788          Crloc  := No_Location;
1789          Prevt  := 'm';
1790
1791          --  Loop to output references
1792
1793          for Refno in 1 .. Nrefs loop
1794             Output_One_Ref : declare
1795                Ent : Entity_Id;
1796
1797                XE : Xref_Entry renames Xrefs.Table (Rnums (Refno));
1798                --  The current entry to be accessed
1799
1800                Left  : Character;
1801                Right : Character;
1802                --  Used for {} or <> or () for type reference
1803
1804                procedure Check_Type_Reference
1805                  (Ent            : Entity_Id;
1806                   List_Interface : Boolean);
1807                --  Find whether there is a meaningful type reference for
1808                --  Ent, and display it accordingly. If List_Interface is
1809                --  true, then Ent is a progenitor interface of the current
1810                --  type entity being listed. In that case list it as is,
1811                --  without looking for a type reference for it.
1812
1813                procedure Output_Instantiation_Refs (Loc : Source_Ptr);
1814                --  Recursive procedure to output instantiation references for
1815                --  the given source ptr in [file|line[...]] form. No output
1816                --  if the given location is not a generic template reference.
1817
1818                procedure Output_Overridden_Op (Old_E : Entity_Id);
1819                --  For a subprogram that is overriding, display information
1820                --  about the inherited operation that it overrides.
1821
1822                --------------------------
1823                -- Check_Type_Reference --
1824                --------------------------
1825
1826                procedure Check_Type_Reference
1827                  (Ent            : Entity_Id;
1828                   List_Interface : Boolean)
1829                is
1830                begin
1831                   if List_Interface then
1832
1833                      --  This is a progenitor interface of the type for which
1834                      --  xref information is being generated.
1835
1836                      Tref  := Ent;
1837                      Left  := '<';
1838                      Right := '>';
1839
1840                   else
1841                      Get_Type_Reference (Ent, Tref, Left, Right);
1842                   end if;
1843
1844                   if Present (Tref) then
1845
1846                      --  Case of standard entity, output name
1847
1848                      if Sloc (Tref) = Standard_Location then
1849                         Write_Info_Char (Left);
1850                         Write_Info_Name (Chars (Tref));
1851                         Write_Info_Char (Right);
1852
1853                      --  Case of source entity, output location
1854
1855                      else
1856                         Write_Info_Char (Left);
1857                         Trunit := Get_Source_Unit (Sloc (Tref));
1858
1859                         if Trunit /= Curxu then
1860                            Write_Info_Nat (Dependency_Num (Trunit));
1861                            Write_Info_Char ('|');
1862                         end if;
1863
1864                         Write_Info_Nat
1865                           (Int (Get_Logical_Line_Number (Sloc (Tref))));
1866
1867                         declare
1868                            Ent  : Entity_Id;
1869                            Ctyp : Character;
1870
1871                         begin
1872                            Ent := Tref;
1873                            Ctyp := Xref_Entity_Letters (Ekind (Ent));
1874
1875                            if Ctyp = '+'
1876                              and then Present (Full_View (Ent))
1877                            then
1878                               Ent := Underlying_Type (Ent);
1879
1880                               if Present (Ent) then
1881                                  Ctyp := Xref_Entity_Letters (Ekind (Ent));
1882                               end if;
1883                            end if;
1884
1885                            Write_Info_Char (Ctyp);
1886                         end;
1887
1888                         Write_Info_Nat
1889                           (Int (Get_Column_Number (Sloc (Tref))));
1890
1891                         --  If the type comes from an instantiation, add the
1892                         --  corresponding info.
1893
1894                         Output_Instantiation_Refs (Sloc (Tref));
1895                         Write_Info_Char (Right);
1896                      end if;
1897                   end if;
1898                end Check_Type_Reference;
1899
1900                -------------------------------
1901                -- Output_Instantiation_Refs --
1902                -------------------------------
1903
1904                procedure Output_Instantiation_Refs (Loc : Source_Ptr) is
1905                   Iloc : constant Source_Ptr := Instantiation_Location (Loc);
1906                   Lun  : Unit_Number_Type;
1907                   Cu   : constant Unit_Number_Type := Curru;
1908
1909                begin
1910                   --  Nothing to do if this is not an instantiation
1911
1912                   if Iloc = No_Location then
1913                      return;
1914                   end if;
1915
1916                   --  Output instantiation reference
1917
1918                   Write_Info_Char ('[');
1919                   Lun := Get_Source_Unit (Iloc);
1920
1921                   if Lun /= Curru then
1922                      Curru := Lun;
1923                      Write_Info_Nat (Dependency_Num (Curru));
1924                      Write_Info_Char ('|');
1925                   end if;
1926
1927                   Write_Info_Nat (Int (Get_Logical_Line_Number (Iloc)));
1928
1929                   --  Recursive call to get nested instantiations
1930
1931                   Output_Instantiation_Refs (Iloc);
1932
1933                   --  Output final ] after call to get proper nesting
1934
1935                   Write_Info_Char (']');
1936                   Curru := Cu;
1937                   return;
1938                end Output_Instantiation_Refs;
1939
1940                --------------------------
1941                -- Output_Overridden_Op --
1942                --------------------------
1943
1944                procedure Output_Overridden_Op (Old_E : Entity_Id) is
1945                   Op : Entity_Id;
1946
1947                begin
1948                   --  The overridden operation has an implicit declaration
1949                   --  at the point of derivation. What we want to display
1950                   --  is the original operation, which has the actual body
1951                   --  (or abstract declaration) that is being overridden.
1952                   --  The overridden operation is not always set, e.g. when
1953                   --  it is a predefined operator.
1954
1955                   if No (Old_E) then
1956                      return;
1957
1958                   --  Follow alias chain if one is present
1959
1960                   elsif Present (Alias (Old_E)) then
1961
1962                      --  The subprogram may have been implicitly inherited
1963                      --  through several levels of derivation, so find the
1964                      --  ultimate (source) ancestor.
1965
1966                      Op := Ultimate_Alias (Old_E);
1967
1968                   --  Normal case of no alias present. We omit generated
1969                   --  primitives like tagged equality, that have no source
1970                   --  representation.
1971
1972                   else
1973                      Op := Old_E;
1974                   end if;
1975
1976                   if Present (Op)
1977                     and then Sloc (Op) /= Standard_Location
1978                     and then Comes_From_Source (Op)
1979                   then
1980                      declare
1981                         Loc      : constant Source_Ptr := Sloc (Op);
1982                         Par_Unit : constant Unit_Number_Type :=
1983                                      Get_Source_Unit (Loc);
1984
1985                      begin
1986                         Write_Info_Char ('<');
1987
1988                         if Par_Unit /= Curxu then
1989                            Write_Info_Nat (Dependency_Num (Par_Unit));
1990                            Write_Info_Char ('|');
1991                         end if;
1992
1993                         Write_Info_Nat (Int (Get_Logical_Line_Number (Loc)));
1994                         Write_Info_Char ('p');
1995                         Write_Info_Nat (Int (Get_Column_Number (Loc)));
1996                         Write_Info_Char ('>');
1997                      end;
1998                   end if;
1999                end Output_Overridden_Op;
2000
2001             --  Start of processing for Output_One_Ref
2002
2003             begin
2004                Ent := XE.Key.Ent;
2005                Ctyp := Xref_Entity_Letters (Ekind (Ent));
2006
2007                --  Skip reference if it is the only reference to an entity,
2008                --  and it is an END line reference, and the entity is not in
2009                --  the current extended source. This prevents junk entries
2010                --  consisting only of packages with END lines, where no
2011                --  entity from the package is actually referenced.
2012
2013                if XE.Key.Typ = 'e'
2014                  and then Ent /= Curent
2015                  and then (Refno = Nrefs
2016                             or else
2017                               Ent /= Xrefs.Table (Rnums (Refno + 1)).Key.Ent)
2018                  and then not In_Extended_Main_Source_Unit (Ent)
2019                then
2020                   goto Continue;
2021                end if;
2022
2023                --  For private type, get full view type
2024
2025                if Ctyp = '+'
2026                  and then Present (Full_View (XE.Key.Ent))
2027                then
2028                   Ent := Underlying_Type (Ent);
2029
2030                   if Present (Ent) then
2031                      Ctyp := Xref_Entity_Letters (Ekind (Ent));
2032                   end if;
2033                end if;
2034
2035                --  Special exception for Boolean
2036
2037                if Ctyp = 'E' and then Is_Boolean_Type (Ent) then
2038                   Ctyp := 'B';
2039                end if;
2040
2041                --  For variable reference, get corresponding type
2042
2043                if Ctyp = '*' then
2044                   Ent := Etype (XE.Key.Ent);
2045                   Ctyp := Fold_Lower (Xref_Entity_Letters (Ekind (Ent)));
2046
2047                   --  If variable is private type, get full view type
2048
2049                   if Ctyp = '+'
2050                     and then Present (Full_View (Etype (XE.Key.Ent)))
2051                   then
2052                      Ent := Underlying_Type (Etype (XE.Key.Ent));
2053
2054                      if Present (Ent) then
2055                         Ctyp := Fold_Lower (Xref_Entity_Letters (Ekind (Ent)));
2056                      end if;
2057
2058                   elsif Is_Generic_Type (Ent) then
2059
2060                      --  If the type of the entity is a generic private type,
2061                      --  there is no usable full view, so retain the indication
2062                      --  that this is an object.
2063
2064                      Ctyp := '*';
2065                   end if;
2066
2067                   --  Special handling for access parameters and objects and
2068                   --  components of an anonymous access type.
2069
2070                   if Ekind_In (Etype (XE.Key.Ent),
2071                                E_Anonymous_Access_Type,
2072                                E_Anonymous_Access_Subprogram_Type,
2073                                E_Anonymous_Access_Protected_Subprogram_Type)
2074                   then
2075                      if Is_Formal (XE.Key.Ent)
2076                        or else
2077                          Ekind_In
2078                            (XE.Key.Ent, E_Variable, E_Constant, E_Component)
2079                      then
2080                         Ctyp := 'p';
2081                      end if;
2082
2083                      --  Special handling for Boolean
2084
2085                   elsif Ctyp = 'e' and then Is_Boolean_Type (Ent) then
2086                      Ctyp := 'b';
2087                   end if;
2088                end if;
2089
2090                --  Special handling for abstract types and operations
2091
2092                if Is_Overloadable (XE.Key.Ent)
2093                  and then Is_Abstract_Subprogram (XE.Key.Ent)
2094                then
2095                   if Ctyp = 'U' then
2096                      Ctyp := 'x';            --  Abstract procedure
2097
2098                   elsif Ctyp = 'V' then
2099                      Ctyp := 'y';            --  Abstract function
2100                   end if;
2101
2102                elsif Is_Type (XE.Key.Ent)
2103                  and then Is_Abstract_Type (XE.Key.Ent)
2104                then
2105                   if Is_Interface (XE.Key.Ent) then
2106                      Ctyp := 'h';
2107
2108                   elsif Ctyp = 'R' then
2109                      Ctyp := 'H';            --  Abstract type
2110                   end if;
2111                end if;
2112
2113                --  Only output reference if interesting type of entity
2114
2115                if Ctyp = ' '
2116
2117                --  Suppress references to object definitions, used for local
2118                --  references.
2119
2120                  or else XE.Key.Typ = 'D'
2121                  or else XE.Key.Typ = 'I'
2122
2123                --  Suppress self references, except for bodies that act as
2124                --  specs.
2125
2126                  or else (XE.Key.Loc = XE.Def
2127                            and then
2128                              (XE.Key.Typ /= 'b'
2129                                or else not Is_Subprogram (XE.Key.Ent)))
2130
2131                --  Also suppress definitions of body formals (we only
2132                --  treat these as references, and the references were
2133                --  separately recorded).
2134
2135                  or else (Is_Formal (XE.Key.Ent)
2136                            and then Present (Spec_Entity (XE.Key.Ent)))
2137                then
2138                   null;
2139
2140                else
2141                   --  Start new Xref section if new xref unit
2142
2143                   if XE.Key.Eun /= Curxu then
2144                      if Write_Info_Col > 1 then
2145                         Write_Info_EOL;
2146                      end if;
2147
2148                      Curxu := XE.Key.Eun;
2149
2150                      Write_Info_Initiate ('X');
2151                      Write_Info_Char (' ');
2152                      Write_Info_Nat (Dependency_Num (XE.Key.Eun));
2153                      Write_Info_Char (' ');
2154                      Write_Info_Name
2155                        (Reference_Name (Source_Index (XE.Key.Eun)));
2156                   end if;
2157
2158                   --  Start new Entity line if new entity. Note that we
2159                   --  consider two entities the same if they have the same
2160                   --  name and source location. This causes entities in
2161                   --  instantiations to be treated as though they referred
2162                   --  to the template.
2163
2164                   if No (Curent)
2165                     or else
2166                       (XE.Key.Ent /= Curent
2167                          and then
2168                            (Name_Change (XE.Key.Ent) or else XE.Def /= Curdef))
2169                   then
2170                      Curent := XE.Key.Ent;
2171                      Curdef := XE.Def;
2172
2173                      Get_Unqualified_Name_String (Chars (XE.Key.Ent));
2174                      Curlen := Name_Len;
2175                      Curnam (1 .. Curlen) := Name_Buffer (1 .. Curlen);
2176
2177                      if Write_Info_Col > 1 then
2178                         Write_Info_EOL;
2179                      end if;
2180
2181                      --  Write column number information
2182
2183                      Write_Info_Nat (Int (Get_Logical_Line_Number (XE.Def)));
2184                      Write_Info_Char (Ctyp);
2185                      Write_Info_Nat (Int (Get_Column_Number (XE.Def)));
2186
2187                      --  Write level information
2188
2189                      Write_Level_Info : declare
2190                         function Is_Visible_Generic_Entity
2191                           (E : Entity_Id) return Boolean;
2192                         --  Check whether E is declared in the visible part
2193                         --  of a generic package. For source navigation
2194                         --  purposes, treat this as a visible entity.
2195
2196                         function Is_Private_Record_Component
2197                           (E : Entity_Id) return Boolean;
2198                         --  Check whether E is a non-inherited component of a
2199                         --  private extension. Even if the enclosing record is
2200                         --  public, we want to treat the component as private
2201                         --  for navigation purposes.
2202
2203                         ---------------------------------
2204                         -- Is_Private_Record_Component --
2205                         ---------------------------------
2206
2207                         function Is_Private_Record_Component
2208                           (E : Entity_Id) return Boolean
2209                         is
2210                            S : constant Entity_Id := Scope (E);
2211                         begin
2212                            return
2213                              Ekind (E) = E_Component
2214                                and then Nkind (Declaration_Node (S)) =
2215                                  N_Private_Extension_Declaration
2216                                and then Original_Record_Component (E) = E;
2217                         end Is_Private_Record_Component;
2218
2219                         -------------------------------
2220                         -- Is_Visible_Generic_Entity --
2221                         -------------------------------
2222
2223                         function Is_Visible_Generic_Entity
2224                           (E : Entity_Id) return Boolean
2225                         is
2226                            Par : Node_Id;
2227
2228                         begin
2229                            --  The Present check here is an error defense
2230
2231                            if Present (Scope (E))
2232                              and then Ekind (Scope (E)) /= E_Generic_Package
2233                            then
2234                               return False;
2235                            end if;
2236
2237                            Par := Parent (E);
2238                            while Present (Par) loop
2239                               if
2240                                 Nkind (Par) = N_Generic_Package_Declaration
2241                               then
2242                                  --  Entity is a generic formal
2243
2244                                  return False;
2245
2246                               elsif
2247                                 Nkind (Parent (Par)) = N_Package_Specification
2248                               then
2249                                  return
2250                                    Is_List_Member (Par)
2251                                      and then List_Containing (Par) =
2252                                        Visible_Declarations (Parent (Par));
2253                               else
2254                                  Par := Parent (Par);
2255                               end if;
2256                            end loop;
2257
2258                            return False;
2259                         end Is_Visible_Generic_Entity;
2260
2261                      --  Start of processing for Write_Level_Info
2262
2263                      begin
2264                         if Is_Hidden (Curent)
2265                           or else Is_Private_Record_Component (Curent)
2266                         then
2267                            Write_Info_Char (' ');
2268
2269                         elsif
2270                            Is_Public (Curent)
2271                              or else Is_Visible_Generic_Entity (Curent)
2272                         then
2273                            Write_Info_Char ('*');
2274
2275                         else
2276                            Write_Info_Char (' ');
2277                         end if;
2278                      end Write_Level_Info;
2279
2280                      --  Output entity name. We use the occurrence from the
2281                      --  actual source program at the definition point.
2282
2283                      declare
2284                         Ent_Name : constant String :=
2285                                      Exact_Source_Name (Sloc (XE.Key.Ent));
2286                      begin
2287                         for C in Ent_Name'Range loop
2288                            Write_Info_Char (Ent_Name (C));
2289                         end loop;
2290                      end;
2291
2292                      --  See if we have a renaming reference
2293
2294                      if Is_Object (XE.Key.Ent)
2295                        and then Present (Renamed_Object (XE.Key.Ent))
2296                      then
2297                         Rref := Renamed_Object (XE.Key.Ent);
2298
2299                      elsif Is_Overloadable (XE.Key.Ent)
2300                        and then Nkind (Parent (Declaration_Node (XE.Key.Ent)))
2301                                            = N_Subprogram_Renaming_Declaration
2302                      then
2303                         Rref := Name (Parent (Declaration_Node (XE.Key.Ent)));
2304
2305                      elsif Ekind (XE.Key.Ent) = E_Package
2306                        and then Nkind (Declaration_Node (XE.Key.Ent)) =
2307                                          N_Package_Renaming_Declaration
2308                      then
2309                         Rref := Name (Declaration_Node (XE.Key.Ent));
2310
2311                      else
2312                         Rref := Empty;
2313                      end if;
2314
2315                      if Present (Rref) then
2316                         if Nkind (Rref) = N_Expanded_Name then
2317                            Rref := Selector_Name (Rref);
2318                         end if;
2319
2320                         if Nkind (Rref) = N_Identifier
2321                           or else Nkind (Rref) = N_Operator_Symbol
2322                         then
2323                            null;
2324
2325                         --  For renamed array components, use the array name
2326                         --  for the renamed entity, which reflect the fact that
2327                         --  in general the whole array is aliased.
2328
2329                         elsif Nkind (Rref) = N_Indexed_Component then
2330                            if Nkind (Prefix (Rref)) = N_Identifier then
2331                               Rref := Prefix (Rref);
2332                            elsif Nkind (Prefix (Rref)) = N_Expanded_Name then
2333                               Rref := Selector_Name (Prefix (Rref));
2334                            else
2335                               Rref := Empty;
2336                            end if;
2337
2338                         else
2339                            Rref := Empty;
2340                         end if;
2341                      end if;
2342
2343                      --  Write out renaming reference if we have one
2344
2345                      if Present (Rref) then
2346                         Write_Info_Char ('=');
2347                         Write_Info_Nat
2348                           (Int (Get_Logical_Line_Number (Sloc (Rref))));
2349                         Write_Info_Char (':');
2350                         Write_Info_Nat
2351                           (Int (Get_Column_Number (Sloc (Rref))));
2352                      end if;
2353
2354                      --  Indicate that the entity is in the unit of the current
2355                      --  xref section.
2356
2357                      Curru := Curxu;
2358
2359                      --  Write out information about generic parent, if entity
2360                      --  is an instance.
2361
2362                      if  Is_Generic_Instance (XE.Key.Ent) then
2363                         declare
2364                            Gen_Par : constant Entity_Id :=
2365                                        Generic_Parent
2366                                          (Specification
2367                                             (Unit_Declaration_Node
2368                                                (XE.Key.Ent)));
2369                            Loc     : constant Source_Ptr := Sloc (Gen_Par);
2370                            Gen_U   : constant Unit_Number_Type :=
2371                                        Get_Source_Unit (Loc);
2372
2373                         begin
2374                            Write_Info_Char ('[');
2375
2376                            if Curru /= Gen_U then
2377                               Write_Info_Nat (Dependency_Num (Gen_U));
2378                               Write_Info_Char ('|');
2379                            end if;
2380
2381                            Write_Info_Nat
2382                              (Int (Get_Logical_Line_Number (Loc)));
2383                            Write_Info_Char (']');
2384                         end;
2385                      end if;
2386
2387                      --  See if we have a type reference and if so output
2388
2389                      Check_Type_Reference (XE.Key.Ent, False);
2390
2391                      --  Additional information for types with progenitors
2392
2393                      if Is_Record_Type (XE.Key.Ent)
2394                        and then Present (Interfaces (XE.Key.Ent))
2395                      then
2396                         declare
2397                            Elmt : Elmt_Id :=
2398                                     First_Elmt (Interfaces (XE.Key.Ent));
2399                         begin
2400                            while Present (Elmt) loop
2401                               Check_Type_Reference (Node (Elmt), True);
2402                               Next_Elmt (Elmt);
2403                            end loop;
2404                         end;
2405
2406                      --  For array types, list index types as well. (This is
2407                      --  not C, indexes have distinct types).
2408
2409                      elsif Is_Array_Type (XE.Key.Ent) then
2410                         declare
2411                            Indx : Node_Id;
2412                         begin
2413                            Indx := First_Index (XE.Key.Ent);
2414                            while Present (Indx) loop
2415                               Check_Type_Reference
2416                                 (First_Subtype (Etype (Indx)), True);
2417                               Next_Index (Indx);
2418                            end loop;
2419                         end;
2420                      end if;
2421
2422                      --  If the entity is an overriding operation, write info
2423                      --  on operation that was overridden.
2424
2425                      if Is_Subprogram (XE.Key.Ent)
2426                        and then Present (Overridden_Operation (XE.Key.Ent))
2427                      then
2428                         Output_Overridden_Op
2429                           (Overridden_Operation (XE.Key.Ent));
2430                      end if;
2431
2432                      --  End of processing for entity output
2433
2434                      Crloc := No_Location;
2435                   end if;
2436
2437                   --  Output the reference if it is not as the same location
2438                   --  as the previous one, or it is a read-reference that
2439                   --  indicates that the entity is an in-out actual in a call.
2440
2441                   if XE.Key.Loc /= No_Location
2442                     and then
2443                       (XE.Key.Loc /= Crloc
2444                         or else (Prevt = 'm' and then  XE.Key.Typ = 'r'))
2445                   then
2446                      Crloc := XE.Key.Loc;
2447                      Prevt := XE.Key.Typ;
2448
2449                      --  Start continuation if line full, else blank
2450
2451                      if Write_Info_Col > 72 then
2452                         Write_Info_EOL;
2453                         Write_Info_Initiate ('.');
2454                      end if;
2455
2456                      Write_Info_Char (' ');
2457
2458                      --  Output file number if changed
2459
2460                      if XE.Key.Lun /= Curru then
2461                         Curru := XE.Key.Lun;
2462                         Write_Info_Nat (Dependency_Num (Curru));
2463                         Write_Info_Char ('|');
2464                      end if;
2465
2466                      Write_Info_Nat
2467                        (Int (Get_Logical_Line_Number (XE.Key.Loc)));
2468                      Write_Info_Char (XE.Key.Typ);
2469
2470                      if Is_Overloadable (XE.Key.Ent) then
2471                         if (Is_Imported (XE.Key.Ent) and then XE.Key.Typ = 'b')
2472                              or else
2473                            (Is_Exported (XE.Key.Ent) and then XE.Key.Typ = 'i')
2474                         then
2475                            Output_Import_Export_Info (XE.Key.Ent);
2476                         end if;
2477                      end if;
2478
2479                      Write_Info_Nat (Int (Get_Column_Number (XE.Key.Loc)));
2480
2481                      Output_Instantiation_Refs (Sloc (XE.Key.Ent));
2482                   end if;
2483                end if;
2484             end Output_One_Ref;
2485
2486          <<Continue>>
2487             null;
2488          end loop;
2489
2490          Write_Info_EOL;
2491       end Output_Refs;
2492    end Output_References;
2493
2494 --  Start of elaboration for Lib.Xref
2495
2496 begin
2497    --  Reset is necessary because Elmt_Ptr does not default to Null_Ptr,
2498    --  because it's not an access type.
2499
2500    Xref_Set.Reset;
2501 end Lib.Xref;