1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2010, Free Software Foundation, Inc. --
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. --
21 -- As a special exception, if other files instantiate generics from this --
22 -- unit, or you link this unit with other files to produce an executable, --
23 -- this unit does not by itself cause the resulting executable to be --
24 -- covered by the GNU General Public License. This exception does not --
25 -- however invalidate any other reasons why the executable file might be --
26 -- covered by the GNU Public License. --
28 -- GNAT was originally developed by the GNAT team at New York University. --
29 -- Extensive contributions were provided by Ada Core Technologies Inc. --
31 ------------------------------------------------------------------------------
33 with Atree; use Atree;
34 with Einfo; use Einfo;
35 with Namet; use Namet;
36 with Sinfo; use Sinfo;
37 with Snames; use Snames;
38 with Stand; use Stand;
40 package body Sem_Aux is
42 ----------------------
43 -- Ancestor_Subtype --
44 ----------------------
46 function Ancestor_Subtype (Typ : Entity_Id) return Entity_Id is
48 -- If this is first subtype, or is a base type, then there is no
49 -- ancestor subtype, so we return Empty to indicate this fact.
51 if Is_First_Subtype (Typ) or else Is_Base_Type (Typ) then
56 D : constant Node_Id := Declaration_Node (Typ);
59 -- If we have a subtype declaration, get the ancestor subtype
61 if Nkind (D) = N_Subtype_Declaration then
62 if Nkind (Subtype_Indication (D)) = N_Subtype_Indication then
63 return Entity (Subtype_Mark (Subtype_Indication (D)));
65 return Entity (Subtype_Indication (D));
68 -- If not, then no subtype indication is available
80 function Available_View (Typ : Entity_Id) return Entity_Id is
82 if Is_Incomplete_Type (Typ)
83 and then Present (Non_Limited_View (Typ))
85 -- The non-limited view may itself be an incomplete type, in which
86 -- case get its full view.
88 return Get_Full_View (Non_Limited_View (Typ));
90 elsif Is_Class_Wide_Type (Typ)
91 and then Is_Incomplete_Type (Etype (Typ))
92 and then Present (Non_Limited_View (Etype (Typ)))
94 return Class_Wide_Type (Non_Limited_View (Etype (Typ)));
105 function Constant_Value (Ent : Entity_Id) return Node_Id is
106 D : constant Node_Id := Declaration_Node (Ent);
110 -- If we have no declaration node, then return no constant value. Not
111 -- clear how this can happen, but it does sometimes and this is the
117 -- Normal case where a declaration node is present
119 elsif Nkind (D) = N_Object_Renaming_Declaration then
120 return Renamed_Object (Ent);
122 -- If this is a component declaration whose entity is a constant, it is
123 -- a prival within a protected function (and so has no constant value).
125 elsif Nkind (D) = N_Component_Declaration then
128 -- If there is an expression, return it
130 elsif Present (Expression (D)) then
131 return (Expression (D));
133 -- For a constant, see if we have a full view
135 elsif Ekind (Ent) = E_Constant
136 and then Present (Full_View (Ent))
138 Full_D := Parent (Full_View (Ent));
140 -- The full view may have been rewritten as an object renaming
142 if Nkind (Full_D) = N_Object_Renaming_Declaration then
143 return Name (Full_D);
145 return Expression (Full_D);
148 -- Otherwise we have no expression to return
155 -----------------------------
156 -- Enclosing_Dynamic_Scope --
157 -----------------------------
159 function Enclosing_Dynamic_Scope (Ent : Entity_Id) return Entity_Id is
163 -- The following test is an error defense against some syntax errors
164 -- that can leave scopes very messed up.
166 if Ent = Standard_Standard then
170 -- Normal case, search enclosing scopes
172 -- Note: the test for Present (S) should not be required, it defends
173 -- against an ill-formed tree.
177 -- If we somehow got an empty value for Scope, the tree must be
178 -- malformed. Rather than blow up we return Standard in this case.
181 return Standard_Standard;
183 -- Quit if we get to standard or a dynamic scope
185 elsif S = Standard_Standard
186 or else Is_Dynamic_Scope (S)
190 -- Otherwise keep climbing
196 end Enclosing_Dynamic_Scope;
198 ------------------------
199 -- First_Discriminant --
200 ------------------------
202 function First_Discriminant (Typ : Entity_Id) return Entity_Id is
207 (Has_Discriminants (Typ) or else Has_Unknown_Discriminants (Typ));
209 Ent := First_Entity (Typ);
211 -- The discriminants are not necessarily contiguous, because access
212 -- discriminants will generate itypes. They are not the first entities
213 -- either, because tag and controller record must be ahead of them.
215 if Chars (Ent) = Name_uTag then
216 Ent := Next_Entity (Ent);
219 if Chars (Ent) = Name_uController then
220 Ent := Next_Entity (Ent);
223 -- Skip all hidden stored discriminants if any
225 while Present (Ent) loop
226 exit when Ekind (Ent) = E_Discriminant
227 and then not Is_Completely_Hidden (Ent);
229 Ent := Next_Entity (Ent);
232 pragma Assert (Ekind (Ent) = E_Discriminant);
235 end First_Discriminant;
237 -------------------------------
238 -- First_Stored_Discriminant --
239 -------------------------------
241 function First_Stored_Discriminant (Typ : Entity_Id) return Entity_Id is
244 function Has_Completely_Hidden_Discriminant
245 (Typ : Entity_Id) return Boolean;
246 -- Scans the Discriminants to see whether any are Completely_Hidden
247 -- (the mechanism for describing non-specified stored discriminants)
249 ----------------------------------------
250 -- Has_Completely_Hidden_Discriminant --
251 ----------------------------------------
253 function Has_Completely_Hidden_Discriminant
254 (Typ : Entity_Id) return Boolean
259 pragma Assert (Ekind (Typ) = E_Discriminant);
262 while Present (Ent) and then Ekind (Ent) = E_Discriminant loop
263 if Is_Completely_Hidden (Ent) then
267 Ent := Next_Entity (Ent);
271 end Has_Completely_Hidden_Discriminant;
273 -- Start of processing for First_Stored_Discriminant
277 (Has_Discriminants (Typ)
278 or else Has_Unknown_Discriminants (Typ));
280 Ent := First_Entity (Typ);
282 if Chars (Ent) = Name_uTag then
283 Ent := Next_Entity (Ent);
286 if Chars (Ent) = Name_uController then
287 Ent := Next_Entity (Ent);
290 if Has_Completely_Hidden_Discriminant (Ent) then
292 while Present (Ent) loop
293 exit when Is_Completely_Hidden (Ent);
294 Ent := Next_Entity (Ent);
299 pragma Assert (Ekind (Ent) = E_Discriminant);
302 end First_Stored_Discriminant;
308 function First_Subtype (Typ : Entity_Id) return Entity_Id is
309 B : constant Entity_Id := Base_Type (Typ);
310 F : constant Node_Id := Freeze_Node (B);
314 -- If the base type has no freeze node, it is a type in Standard, and
315 -- always acts as its own first subtype, except where it is one of the
316 -- predefined integer types. If the type is formal, it is also a first
317 -- subtype, and its base type has no freeze node. On the other hand, a
318 -- subtype of a generic formal is not its own first subtype. Its base
319 -- type, if anonymous, is attached to the formal type decl. from which
320 -- the first subtype is obtained.
323 if B = Base_Type (Standard_Integer) then
324 return Standard_Integer;
326 elsif B = Base_Type (Standard_Long_Integer) then
327 return Standard_Long_Integer;
329 elsif B = Base_Type (Standard_Short_Short_Integer) then
330 return Standard_Short_Short_Integer;
332 elsif B = Base_Type (Standard_Short_Integer) then
333 return Standard_Short_Integer;
335 elsif B = Base_Type (Standard_Long_Long_Integer) then
336 return Standard_Long_Long_Integer;
338 elsif Is_Generic_Type (Typ) then
339 if Present (Parent (B)) then
340 return Defining_Identifier (Parent (B));
342 return Defining_Identifier (Associated_Node_For_Itype (B));
349 -- Otherwise we check the freeze node, if it has a First_Subtype_Link
350 -- then we use that link, otherwise (happens with some Itypes), we use
351 -- the base type itself.
354 Ent := First_Subtype_Link (F);
356 if Present (Ent) then
364 -------------------------
365 -- First_Tag_Component --
366 -------------------------
368 function First_Tag_Component (Typ : Entity_Id) return Entity_Id is
374 pragma Assert (Is_Tagged_Type (Ctyp));
376 if Is_Class_Wide_Type (Ctyp) then
377 Ctyp := Root_Type (Ctyp);
380 if Is_Private_Type (Ctyp) then
381 Ctyp := Underlying_Type (Ctyp);
383 -- If the underlying type is missing then the source program has
384 -- errors and there is nothing else to do (the full-type declaration
385 -- associated with the private type declaration is missing).
392 Comp := First_Entity (Ctyp);
393 while Present (Comp) loop
394 if Is_Tag (Comp) then
398 Comp := Next_Entity (Comp);
401 -- No tag component found
404 end First_Tag_Component;
406 -------------------------------
407 -- Initialization_Suppressed --
408 -------------------------------
410 function Initialization_Suppressed (Typ : Entity_Id) return Boolean is
412 return Suppress_Initialization (Typ)
413 or else Suppress_Initialization (Base_Type (Typ));
414 end Initialization_Suppressed;
420 procedure Initialize is
422 Obsolescent_Warnings.Init;
425 ---------------------
426 -- Is_By_Copy_Type --
427 ---------------------
429 function Is_By_Copy_Type (Ent : Entity_Id) return Boolean is
431 -- If Id is a private type whose full declaration has not been seen,
432 -- we assume for now that it is not a By_Copy type. Clearly this
433 -- attribute should not be used before the type is frozen, but it is
434 -- needed to build the associated record of a protected type. Another
435 -- place where some lookahead for a full view is needed ???
438 Is_Elementary_Type (Ent)
439 or else (Is_Private_Type (Ent)
440 and then Present (Underlying_Type (Ent))
441 and then Is_Elementary_Type (Underlying_Type (Ent)));
444 --------------------------
445 -- Is_By_Reference_Type --
446 --------------------------
448 function Is_By_Reference_Type (Ent : Entity_Id) return Boolean is
449 Btype : constant Entity_Id := Base_Type (Ent);
452 if Error_Posted (Ent)
453 or else Error_Posted (Btype)
457 elsif Is_Private_Type (Btype) then
459 Utyp : constant Entity_Id := Underlying_Type (Btype);
464 return Is_By_Reference_Type (Utyp);
468 elsif Is_Incomplete_Type (Btype) then
470 Ftyp : constant Entity_Id := Full_View (Btype);
475 return Is_By_Reference_Type (Ftyp);
479 elsif Is_Concurrent_Type (Btype) then
482 elsif Is_Record_Type (Btype) then
483 if Is_Limited_Record (Btype)
484 or else Is_Tagged_Type (Btype)
485 or else Is_Volatile (Btype)
494 C := First_Component (Btype);
495 while Present (C) loop
496 if Is_By_Reference_Type (Etype (C))
497 or else Is_Volatile (Etype (C))
502 C := Next_Component (C);
509 elsif Is_Array_Type (Btype) then
512 or else Is_By_Reference_Type (Component_Type (Btype))
513 or else Is_Volatile (Component_Type (Btype))
514 or else Has_Volatile_Components (Btype);
519 end Is_By_Reference_Type;
521 ---------------------
522 -- Is_Derived_Type --
523 ---------------------
525 function Is_Derived_Type (Ent : E) return B is
530 and then Base_Type (Ent) /= Root_Type (Ent)
531 and then not Is_Class_Wide_Type (Ent)
533 if not Is_Numeric_Type (Root_Type (Ent)) then
537 Par := Parent (First_Subtype (Ent));
540 and then Nkind (Par) = N_Full_Type_Declaration
541 and then Nkind (Type_Definition (Par)) =
542 N_Derived_Type_Definition;
550 -----------------------
551 -- Is_Generic_Formal --
552 -----------------------
554 function Is_Generic_Formal (E : Entity_Id) return Boolean is
560 Kind := Nkind (Parent (E));
562 Nkind_In (Kind, N_Formal_Object_Declaration,
563 N_Formal_Package_Declaration,
564 N_Formal_Type_Declaration)
565 or else Is_Formal_Subprogram (E);
567 end Is_Generic_Formal;
569 ---------------------------
570 -- Is_Indefinite_Subtype --
571 ---------------------------
573 function Is_Indefinite_Subtype (Ent : Entity_Id) return Boolean is
574 K : constant Entity_Kind := Ekind (Ent);
577 if Is_Constrained (Ent) then
580 elsif K in Array_Kind
581 or else K in Class_Wide_Kind
582 or else Has_Unknown_Discriminants (Ent)
586 -- Known discriminants: indefinite if there are no default values
588 elsif K in Record_Kind
589 or else Is_Incomplete_Or_Private_Type (Ent)
590 or else Is_Concurrent_Type (Ent)
592 return (Has_Discriminants (Ent)
594 No (Discriminant_Default_Value (First_Discriminant (Ent))));
599 end Is_Indefinite_Subtype;
601 -------------------------------
602 -- Is_Immutably_Limited_Type --
603 -------------------------------
605 function Is_Immutably_Limited_Type (Ent : Entity_Id) return Boolean is
606 Btype : constant Entity_Id := Base_Type (Ent);
609 if Is_Limited_Record (Btype) then
612 elsif Ekind (Btype) = E_Limited_Private_Type
613 and then Nkind (Parent (Btype)) = N_Formal_Type_Declaration
615 return not In_Package_Body (Scope ((Btype)));
618 if Is_Private_Type (Btype) then
620 -- AI05-0063: A type derived from a limited private formal type is
621 -- not immutably limited in a generic body.
623 if Is_Derived_Type (Btype)
624 and then Is_Generic_Type (Etype (Btype))
626 if not Is_Limited_Type (Etype (Btype)) then
629 -- A descendant of a limited formal type is not immutably limited
630 -- in the generic body, or in the body of a generic child.
632 elsif Ekind (Scope (Etype (Btype))) = E_Generic_Package then
633 return not In_Package_Body (Scope (Btype));
641 Utyp : constant Entity_Id := Underlying_Type (Btype);
646 return Is_Immutably_Limited_Type (Utyp);
651 elsif Is_Concurrent_Type (Btype) then
654 elsif Is_Record_Type (Btype) then
656 -- Note that we return True for all limited interfaces, even though
657 -- (unsynchronized) limited interfaces can have descendants that are
658 -- nonlimited, because this is a predicate on the type itself, and
659 -- things like functions with limited interface results need to be
660 -- handled as build in place even though they might return objects
661 -- of a type that is not inherently limited.
663 if Is_Class_Wide_Type (Btype) then
664 return Is_Immutably_Limited_Type (Root_Type (Btype));
671 C := First_Component (Btype);
672 while Present (C) loop
674 -- Don't consider components with interface types (which can
675 -- only occur in the case of a _parent component anyway).
676 -- They don't have any components, plus it would cause this
677 -- function to return true for nonlimited types derived from
678 -- limited interfaces.
680 if not Is_Interface (Etype (C))
681 and then Is_Immutably_Limited_Type (Etype (C))
686 C := Next_Component (C);
693 elsif Is_Array_Type (Btype) then
694 return Is_Immutably_Limited_Type (Component_Type (Btype));
699 end Is_Immutably_Limited_Type;
701 ---------------------
702 -- Is_Limited_Type --
703 ---------------------
705 function Is_Limited_Type (Ent : Entity_Id) return Boolean is
706 Btype : constant E := Base_Type (Ent);
707 Rtype : constant E := Root_Type (Btype);
710 if not Is_Type (Ent) then
713 elsif Ekind (Btype) = E_Limited_Private_Type
714 or else Is_Limited_Composite (Btype)
718 elsif Is_Concurrent_Type (Btype) then
721 -- The Is_Limited_Record flag normally indicates that the type is
722 -- limited. The exception is that a type does not inherit limitedness
723 -- from its interface ancestor. So the type may be derived from a
724 -- limited interface, but is not limited.
726 elsif Is_Limited_Record (Ent)
727 and then not Is_Interface (Ent)
731 -- Otherwise we will look around to see if there is some other reason
732 -- for it to be limited, except that if an error was posted on the
733 -- entity, then just assume it is non-limited, because it can cause
734 -- trouble to recurse into a murky erroneous entity!
736 elsif Error_Posted (Ent) then
739 elsif Is_Record_Type (Btype) then
741 if Is_Limited_Interface (Ent) then
744 -- AI-419: limitedness is not inherited from a limited interface
746 elsif Is_Limited_Record (Rtype) then
747 return not Is_Interface (Rtype)
748 or else Is_Protected_Interface (Rtype)
749 or else Is_Synchronized_Interface (Rtype)
750 or else Is_Task_Interface (Rtype);
752 elsif Is_Class_Wide_Type (Btype) then
753 return Is_Limited_Type (Rtype);
760 C := First_Component (Btype);
761 while Present (C) loop
762 if Is_Limited_Type (Etype (C)) then
766 C := Next_Component (C);
773 elsif Is_Array_Type (Btype) then
774 return Is_Limited_Type (Component_Type (Btype));
781 ----------------------
782 -- Nearest_Ancestor --
783 ----------------------
785 function Nearest_Ancestor (Typ : Entity_Id) return Entity_Id is
786 D : constant Node_Id := Declaration_Node (Typ);
789 -- If we have a subtype declaration, get the ancestor subtype
791 if Nkind (D) = N_Subtype_Declaration then
792 if Nkind (Subtype_Indication (D)) = N_Subtype_Indication then
793 return Entity (Subtype_Mark (Subtype_Indication (D)));
795 return Entity (Subtype_Indication (D));
798 -- If derived type declaration, find who we are derived from
800 elsif Nkind (D) = N_Full_Type_Declaration
801 and then Nkind (Type_Definition (D)) = N_Derived_Type_Definition
804 DTD : constant Entity_Id := Type_Definition (D);
805 SI : constant Entity_Id := Subtype_Indication (DTD);
807 if Is_Entity_Name (SI) then
810 return Entity (Subtype_Mark (SI));
814 -- Otherwise, nothing useful to return, return Empty
819 end Nearest_Ancestor;
821 ---------------------------
822 -- Nearest_Dynamic_Scope --
823 ---------------------------
825 function Nearest_Dynamic_Scope (Ent : Entity_Id) return Entity_Id is
827 if Is_Dynamic_Scope (Ent) then
830 return Enclosing_Dynamic_Scope (Ent);
832 end Nearest_Dynamic_Scope;
834 ------------------------
835 -- Next_Tag_Component --
836 ------------------------
838 function Next_Tag_Component (Tag : Entity_Id) return Entity_Id is
842 pragma Assert (Is_Tag (Tag));
844 -- Loop to look for next tag component
846 Comp := Next_Entity (Tag);
847 while Present (Comp) loop
848 if Is_Tag (Comp) then
849 pragma Assert (Chars (Comp) /= Name_uTag);
853 Comp := Next_Entity (Comp);
856 -- No tag component found
859 end Next_Tag_Component;
861 --------------------------
862 -- Number_Discriminants --
863 --------------------------
865 function Number_Discriminants (Typ : Entity_Id) return Pos is
871 Discr := First_Discriminant (Typ);
872 while Present (Discr) loop
874 Discr := Next_Discriminant (Discr);
878 end Number_Discriminants;
884 procedure Tree_Read is
886 Obsolescent_Warnings.Tree_Read;
893 procedure Tree_Write is
895 Obsolescent_Warnings.Tree_Write;
902 function Ultimate_Alias (Prim : Entity_Id) return Entity_Id is
903 E : Entity_Id := Prim;
906 while Present (Alias (E)) loop
907 pragma Assert (Alias (E) /= E);