1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, 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. We must also
184 -- handle enclosing scopes that have a full view; required to
185 -- locate enclosing scopes that are synchronized private types
186 -- whose full view is a task type.
188 elsif S = Standard_Standard
189 or else Is_Dynamic_Scope (S)
190 or else (Is_Private_Type (S)
191 and then Present (Full_View (S))
192 and then Is_Dynamic_Scope (Full_View (S)))
196 -- Otherwise keep climbing
202 end Enclosing_Dynamic_Scope;
204 ------------------------
205 -- First_Discriminant --
206 ------------------------
208 function First_Discriminant (Typ : Entity_Id) return Entity_Id is
213 (Has_Discriminants (Typ) or else Has_Unknown_Discriminants (Typ));
215 Ent := First_Entity (Typ);
217 -- The discriminants are not necessarily contiguous, because access
218 -- discriminants will generate itypes. They are not the first entities
219 -- either because the tag must be ahead of them.
221 if Chars (Ent) = Name_uTag then
222 Ent := Next_Entity (Ent);
225 -- Skip all hidden stored discriminants if any
227 while Present (Ent) loop
228 exit when Ekind (Ent) = E_Discriminant
229 and then not Is_Completely_Hidden (Ent);
231 Ent := Next_Entity (Ent);
234 pragma Assert (Ekind (Ent) = E_Discriminant);
237 end First_Discriminant;
239 -------------------------------
240 -- First_Stored_Discriminant --
241 -------------------------------
243 function First_Stored_Discriminant (Typ : Entity_Id) return Entity_Id is
246 function Has_Completely_Hidden_Discriminant
247 (Typ : Entity_Id) return Boolean;
248 -- Scans the Discriminants to see whether any are Completely_Hidden
249 -- (the mechanism for describing non-specified stored discriminants)
251 ----------------------------------------
252 -- Has_Completely_Hidden_Discriminant --
253 ----------------------------------------
255 function Has_Completely_Hidden_Discriminant
256 (Typ : Entity_Id) return Boolean
261 pragma Assert (Ekind (Typ) = E_Discriminant);
264 while Present (Ent) and then Ekind (Ent) = E_Discriminant loop
265 if Is_Completely_Hidden (Ent) then
269 Ent := Next_Entity (Ent);
273 end Has_Completely_Hidden_Discriminant;
275 -- Start of processing for First_Stored_Discriminant
279 (Has_Discriminants (Typ)
280 or else Has_Unknown_Discriminants (Typ));
282 Ent := First_Entity (Typ);
284 if Chars (Ent) = Name_uTag then
285 Ent := Next_Entity (Ent);
288 if Has_Completely_Hidden_Discriminant (Ent) then
289 while Present (Ent) loop
290 exit when Is_Completely_Hidden (Ent);
291 Ent := Next_Entity (Ent);
295 pragma Assert (Ekind (Ent) = E_Discriminant);
298 end First_Stored_Discriminant;
304 function First_Subtype (Typ : Entity_Id) return Entity_Id is
305 B : constant Entity_Id := Base_Type (Typ);
306 F : constant Node_Id := Freeze_Node (B);
310 -- If the base type has no freeze node, it is a type in Standard, and
311 -- always acts as its own first subtype, except where it is one of the
312 -- predefined integer types. If the type is formal, it is also a first
313 -- subtype, and its base type has no freeze node. On the other hand, a
314 -- subtype of a generic formal is not its own first subtype. Its base
315 -- type, if anonymous, is attached to the formal type decl. from which
316 -- the first subtype is obtained.
319 if B = Base_Type (Standard_Integer) then
320 return Standard_Integer;
322 elsif B = Base_Type (Standard_Long_Integer) then
323 return Standard_Long_Integer;
325 elsif B = Base_Type (Standard_Short_Short_Integer) then
326 return Standard_Short_Short_Integer;
328 elsif B = Base_Type (Standard_Short_Integer) then
329 return Standard_Short_Integer;
331 elsif B = Base_Type (Standard_Long_Long_Integer) then
332 return Standard_Long_Long_Integer;
334 elsif Is_Generic_Type (Typ) then
335 if Present (Parent (B)) then
336 return Defining_Identifier (Parent (B));
338 return Defining_Identifier (Associated_Node_For_Itype (B));
345 -- Otherwise we check the freeze node, if it has a First_Subtype_Link
346 -- then we use that link, otherwise (happens with some Itypes), we use
347 -- the base type itself.
350 Ent := First_Subtype_Link (F);
352 if Present (Ent) then
360 -------------------------
361 -- First_Tag_Component --
362 -------------------------
364 function First_Tag_Component (Typ : Entity_Id) return Entity_Id is
370 pragma Assert (Is_Tagged_Type (Ctyp));
372 if Is_Class_Wide_Type (Ctyp) then
373 Ctyp := Root_Type (Ctyp);
376 if Is_Private_Type (Ctyp) then
377 Ctyp := Underlying_Type (Ctyp);
379 -- If the underlying type is missing then the source program has
380 -- errors and there is nothing else to do (the full-type declaration
381 -- associated with the private type declaration is missing).
388 Comp := First_Entity (Ctyp);
389 while Present (Comp) loop
390 if Is_Tag (Comp) then
394 Comp := Next_Entity (Comp);
397 -- No tag component found
400 end First_Tag_Component;
402 -------------------------------
403 -- Initialization_Suppressed --
404 -------------------------------
406 function Initialization_Suppressed (Typ : Entity_Id) return Boolean is
408 return Suppress_Initialization (Typ)
409 or else Suppress_Initialization (Base_Type (Typ));
410 end Initialization_Suppressed;
416 procedure Initialize is
418 Obsolescent_Warnings.Init;
421 ---------------------
422 -- Is_By_Copy_Type --
423 ---------------------
425 function Is_By_Copy_Type (Ent : Entity_Id) return Boolean is
427 -- If Id is a private type whose full declaration has not been seen,
428 -- we assume for now that it is not a By_Copy type. Clearly this
429 -- attribute should not be used before the type is frozen, but it is
430 -- needed to build the associated record of a protected type. Another
431 -- place where some lookahead for a full view is needed ???
434 Is_Elementary_Type (Ent)
435 or else (Is_Private_Type (Ent)
436 and then Present (Underlying_Type (Ent))
437 and then Is_Elementary_Type (Underlying_Type (Ent)));
440 --------------------------
441 -- Is_By_Reference_Type --
442 --------------------------
444 function Is_By_Reference_Type (Ent : Entity_Id) return Boolean is
445 Btype : constant Entity_Id := Base_Type (Ent);
448 if Error_Posted (Ent) or else Error_Posted (Btype) then
451 elsif Is_Private_Type (Btype) then
453 Utyp : constant Entity_Id := Underlying_Type (Btype);
458 return Is_By_Reference_Type (Utyp);
462 elsif Is_Incomplete_Type (Btype) then
464 Ftyp : constant Entity_Id := Full_View (Btype);
469 return Is_By_Reference_Type (Ftyp);
473 elsif Is_Concurrent_Type (Btype) then
476 elsif Is_Record_Type (Btype) then
477 if Is_Limited_Record (Btype)
478 or else Is_Tagged_Type (Btype)
479 or else Is_Volatile (Btype)
488 C := First_Component (Btype);
489 while Present (C) loop
490 if Is_By_Reference_Type (Etype (C))
491 or else Is_Volatile (Etype (C))
496 C := Next_Component (C);
503 elsif Is_Array_Type (Btype) then
506 or else Is_By_Reference_Type (Component_Type (Btype))
507 or else Is_Volatile (Component_Type (Btype))
508 or else Has_Volatile_Components (Btype);
513 end Is_By_Reference_Type;
515 ---------------------
516 -- Is_Derived_Type --
517 ---------------------
519 function Is_Derived_Type (Ent : E) return B is
524 and then Base_Type (Ent) /= Root_Type (Ent)
525 and then not Is_Class_Wide_Type (Ent)
527 if not Is_Numeric_Type (Root_Type (Ent)) then
531 Par := Parent (First_Subtype (Ent));
534 and then Nkind (Par) = N_Full_Type_Declaration
535 and then Nkind (Type_Definition (Par)) =
536 N_Derived_Type_Definition;
544 -----------------------
545 -- Is_Generic_Formal --
546 -----------------------
548 function Is_Generic_Formal (E : Entity_Id) return Boolean is
554 Kind := Nkind (Parent (E));
556 Nkind_In (Kind, N_Formal_Object_Declaration,
557 N_Formal_Package_Declaration,
558 N_Formal_Type_Declaration)
559 or else Is_Formal_Subprogram (E);
561 end Is_Generic_Formal;
563 ---------------------------
564 -- Is_Indefinite_Subtype --
565 ---------------------------
567 function Is_Indefinite_Subtype (Ent : Entity_Id) return Boolean is
568 K : constant Entity_Kind := Ekind (Ent);
571 if Is_Constrained (Ent) then
574 elsif K in Array_Kind
575 or else K in Class_Wide_Kind
576 or else Has_Unknown_Discriminants (Ent)
580 -- Known discriminants: indefinite if there are no default values
582 elsif K in Record_Kind
583 or else Is_Incomplete_Or_Private_Type (Ent)
584 or else Is_Concurrent_Type (Ent)
586 return (Has_Discriminants (Ent)
588 No (Discriminant_Default_Value (First_Discriminant (Ent))));
593 end Is_Indefinite_Subtype;
595 -------------------------------
596 -- Is_Immutably_Limited_Type --
597 -------------------------------
599 function Is_Immutably_Limited_Type (Ent : Entity_Id) return Boolean is
600 Btype : constant Entity_Id := Available_View (Base_Type (Ent));
603 if Is_Limited_Record (Btype) then
606 elsif Ekind (Btype) = E_Limited_Private_Type
607 and then Nkind (Parent (Btype)) = N_Formal_Type_Declaration
609 return not In_Package_Body (Scope ((Btype)));
611 elsif Is_Private_Type (Btype) then
613 -- AI05-0063: A type derived from a limited private formal type is
614 -- not immutably limited in a generic body.
616 if Is_Derived_Type (Btype)
617 and then Is_Generic_Type (Etype (Btype))
619 if not Is_Limited_Type (Etype (Btype)) then
622 -- A descendant of a limited formal type is not immutably limited
623 -- in the generic body, or in the body of a generic child.
625 elsif Ekind (Scope (Etype (Btype))) = E_Generic_Package then
626 return not In_Package_Body (Scope (Btype));
634 Utyp : constant Entity_Id := Underlying_Type (Btype);
639 return Is_Immutably_Limited_Type (Utyp);
644 elsif Is_Concurrent_Type (Btype) then
647 elsif Is_Record_Type (Btype) then
649 -- Note that we return True for all limited interfaces, even though
650 -- (unsynchronized) limited interfaces can have descendants that are
651 -- nonlimited, because this is a predicate on the type itself, and
652 -- things like functions with limited interface results need to be
653 -- handled as build in place even though they might return objects
654 -- of a type that is not inherently limited.
656 if Is_Class_Wide_Type (Btype) then
657 return Is_Immutably_Limited_Type (Root_Type (Btype));
664 C := First_Component (Btype);
665 while Present (C) loop
667 -- Don't consider components with interface types (which can
668 -- only occur in the case of a _parent component anyway).
669 -- They don't have any components, plus it would cause this
670 -- function to return true for nonlimited types derived from
671 -- limited interfaces.
673 if not Is_Interface (Etype (C))
674 and then Is_Immutably_Limited_Type (Etype (C))
679 C := Next_Component (C);
686 elsif Is_Array_Type (Btype) then
687 return Is_Immutably_Limited_Type (Component_Type (Btype));
692 end Is_Immutably_Limited_Type;
694 ---------------------
695 -- Is_Limited_Type --
696 ---------------------
698 function Is_Limited_Type (Ent : Entity_Id) return Boolean is
699 Btype : constant E := Base_Type (Ent);
700 Rtype : constant E := Root_Type (Btype);
703 if not Is_Type (Ent) then
706 elsif Ekind (Btype) = E_Limited_Private_Type
707 or else Is_Limited_Composite (Btype)
711 elsif Is_Concurrent_Type (Btype) then
714 -- The Is_Limited_Record flag normally indicates that the type is
715 -- limited. The exception is that a type does not inherit limitedness
716 -- from its interface ancestor. So the type may be derived from a
717 -- limited interface, but is not limited.
719 elsif Is_Limited_Record (Ent)
720 and then not Is_Interface (Ent)
724 -- Otherwise we will look around to see if there is some other reason
725 -- for it to be limited, except that if an error was posted on the
726 -- entity, then just assume it is non-limited, because it can cause
727 -- trouble to recurse into a murky erroneous entity!
729 elsif Error_Posted (Ent) then
732 elsif Is_Record_Type (Btype) then
734 if Is_Limited_Interface (Ent) then
737 -- AI-419: limitedness is not inherited from a limited interface
739 elsif Is_Limited_Record (Rtype) then
740 return not Is_Interface (Rtype)
741 or else Is_Protected_Interface (Rtype)
742 or else Is_Synchronized_Interface (Rtype)
743 or else Is_Task_Interface (Rtype);
745 elsif Is_Class_Wide_Type (Btype) then
746 return Is_Limited_Type (Rtype);
753 C := First_Component (Btype);
754 while Present (C) loop
755 if Is_Limited_Type (Etype (C)) then
759 C := Next_Component (C);
766 elsif Is_Array_Type (Btype) then
767 return Is_Limited_Type (Component_Type (Btype));
774 ----------------------
775 -- Nearest_Ancestor --
776 ----------------------
778 function Nearest_Ancestor (Typ : Entity_Id) return Entity_Id is
779 D : constant Node_Id := Declaration_Node (Typ);
782 -- If we have a subtype declaration, get the ancestor subtype
784 if Nkind (D) = N_Subtype_Declaration then
785 if Nkind (Subtype_Indication (D)) = N_Subtype_Indication then
786 return Entity (Subtype_Mark (Subtype_Indication (D)));
788 return Entity (Subtype_Indication (D));
791 -- If derived type declaration, find who we are derived from
793 elsif Nkind (D) = N_Full_Type_Declaration
794 and then Nkind (Type_Definition (D)) = N_Derived_Type_Definition
797 DTD : constant Entity_Id := Type_Definition (D);
798 SI : constant Entity_Id := Subtype_Indication (DTD);
800 if Is_Entity_Name (SI) then
803 return Entity (Subtype_Mark (SI));
807 -- Otherwise, nothing useful to return, return Empty
812 end Nearest_Ancestor;
814 ---------------------------
815 -- Nearest_Dynamic_Scope --
816 ---------------------------
818 function Nearest_Dynamic_Scope (Ent : Entity_Id) return Entity_Id is
820 if Is_Dynamic_Scope (Ent) then
823 return Enclosing_Dynamic_Scope (Ent);
825 end Nearest_Dynamic_Scope;
827 ------------------------
828 -- Next_Tag_Component --
829 ------------------------
831 function Next_Tag_Component (Tag : Entity_Id) return Entity_Id is
835 pragma Assert (Is_Tag (Tag));
837 -- Loop to look for next tag component
839 Comp := Next_Entity (Tag);
840 while Present (Comp) loop
841 if Is_Tag (Comp) then
842 pragma Assert (Chars (Comp) /= Name_uTag);
846 Comp := Next_Entity (Comp);
849 -- No tag component found
852 end Next_Tag_Component;
854 --------------------------
855 -- Number_Discriminants --
856 --------------------------
858 function Number_Discriminants (Typ : Entity_Id) return Pos is
864 Discr := First_Discriminant (Typ);
865 while Present (Discr) loop
867 Discr := Next_Discriminant (Discr);
871 end Number_Discriminants;
877 procedure Tree_Read is
879 Obsolescent_Warnings.Tree_Read;
886 procedure Tree_Write is
888 Obsolescent_Warnings.Tree_Write;
895 function Ultimate_Alias (Prim : Entity_Id) return Entity_Id is
896 E : Entity_Id := Prim;
899 while Present (Alias (E)) loop
900 pragma Assert (Alias (E) /= E);