1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2008, 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 Typ = 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 constant, it is
123 -- a prival within a protected function. It does not have a constant
126 elsif Nkind (D) = N_Component_Declaration then
129 -- If there is an expression, return it
131 elsif Present (Expression (D)) then
132 return (Expression (D));
134 -- For a constant, see if we have a full view
136 elsif Ekind (Ent) = E_Constant
137 and then Present (Full_View (Ent))
139 Full_D := Parent (Full_View (Ent));
141 -- The full view may have been rewritten as an object renaming
143 if Nkind (Full_D) = N_Object_Renaming_Declaration then
144 return Name (Full_D);
146 return Expression (Full_D);
149 -- Otherwise we have no expression to return
156 -----------------------------
157 -- Enclosing_Dynamic_Scope --
158 -----------------------------
160 function Enclosing_Dynamic_Scope (Ent : Entity_Id) return Entity_Id is
164 -- The following test is an error defense against some syntax errors
165 -- that can leave scopes very messed up.
167 if Ent = Standard_Standard then
171 -- Normal case, search enclosing scopes
173 -- Note: the test for Present (S) should not be required, it is a
174 -- defence against an ill-formed tree.
178 -- If we somehow got an empty value for Scope, the tree must be
179 -- malformed. Rather than blow up we return Standard in this case.
182 return Standard_Standard;
184 -- Quit if we get to standard or a dynamic scope
186 elsif S = Standard_Standard
187 or else Is_Dynamic_Scope (S)
191 -- Otherwise keep climbing
197 end Enclosing_Dynamic_Scope;
199 ------------------------
200 -- First_Discriminant --
201 ------------------------
203 function First_Discriminant (Typ : Entity_Id) return Entity_Id is
208 (Has_Discriminants (Typ)
209 or else Has_Unknown_Discriminants (Typ));
211 Ent := First_Entity (Typ);
213 -- The discriminants are not necessarily contiguous, because access
214 -- discriminants will generate itypes. They are not the first entities
215 -- either, because tag and controller record must be ahead of them.
217 if Chars (Ent) = Name_uTag then
218 Ent := Next_Entity (Ent);
221 if Chars (Ent) = Name_uController 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 Chars (Ent) = Name_uController then
289 Ent := Next_Entity (Ent);
292 if Has_Completely_Hidden_Discriminant (Ent) then
294 while Present (Ent) loop
295 exit when Is_Completely_Hidden (Ent);
296 Ent := Next_Entity (Ent);
301 pragma Assert (Ekind (Ent) = E_Discriminant);
304 end First_Stored_Discriminant;
310 function First_Subtype (Typ : Entity_Id) return Entity_Id is
311 B : constant Entity_Id := Base_Type (Typ);
312 F : constant Node_Id := Freeze_Node (B);
316 -- If the base type has no freeze node, it is a type in standard,
317 -- and always acts as its own first subtype unless it is one of the
318 -- predefined integer types. If the type is formal, it is also a first
319 -- subtype, and its base type has no freeze node. On the other hand, a
320 -- subtype of a generic formal is not its own first_subtype. Its base
321 -- type, if anonymous, is attached to the formal type decl. from which
322 -- the first subtype is obtained.
326 if B = Base_Type (Standard_Integer) then
327 return Standard_Integer;
329 elsif B = Base_Type (Standard_Long_Integer) then
330 return Standard_Long_Integer;
332 elsif B = Base_Type (Standard_Short_Short_Integer) then
333 return Standard_Short_Short_Integer;
335 elsif B = Base_Type (Standard_Short_Integer) then
336 return Standard_Short_Integer;
338 elsif B = Base_Type (Standard_Long_Long_Integer) then
339 return Standard_Long_Long_Integer;
341 elsif Is_Generic_Type (Typ) then
342 if Present (Parent (B)) then
343 return Defining_Identifier (Parent (B));
345 return Defining_Identifier (Associated_Node_For_Itype (B));
352 -- Otherwise we check the freeze node, if it has a First_Subtype_Link
353 -- then we use that link, otherwise (happens with some Itypes), we use
354 -- the base type itself.
357 Ent := First_Subtype_Link (F);
359 if Present (Ent) then
367 -------------------------
368 -- First_Tag_Component --
369 -------------------------
371 function First_Tag_Component (Typ : Entity_Id) return Entity_Id is
377 pragma Assert (Is_Tagged_Type (Ctyp));
379 if Is_Class_Wide_Type (Ctyp) then
380 Ctyp := Root_Type (Ctyp);
383 if Is_Private_Type (Ctyp) then
384 Ctyp := Underlying_Type (Ctyp);
386 -- If the underlying type is missing then the source program has
387 -- errors and there is nothing else to do (the full-type declaration
388 -- associated with the private type declaration is missing).
395 Comp := First_Entity (Ctyp);
396 while Present (Comp) loop
397 if Is_Tag (Comp) then
401 Comp := Next_Entity (Comp);
404 -- No tag component found
407 end First_Tag_Component;
413 procedure Initialize is
415 Obsolescent_Warnings.Init;
418 ---------------------
419 -- Is_By_Copy_Type --
420 ---------------------
422 function Is_By_Copy_Type (Ent : Entity_Id) return Boolean is
424 -- If Id is a private type whose full declaration has not been seen,
425 -- we assume for now that it is not a By_Copy type. Clearly this
426 -- attribute should not be used before the type is frozen, but it is
427 -- needed to build the associated record of a protected type. Another
428 -- place where some lookahead for a full view is needed ???
431 Is_Elementary_Type (Ent)
432 or else (Is_Private_Type (Ent)
433 and then Present (Underlying_Type (Ent))
434 and then Is_Elementary_Type (Underlying_Type (Ent)));
437 --------------------------
438 -- Is_By_Reference_Type --
439 --------------------------
441 function Is_By_Reference_Type (Ent : Entity_Id) return Boolean is
442 Btype : constant Entity_Id := Base_Type (Ent);
445 if Error_Posted (Ent)
446 or else Error_Posted (Btype)
450 elsif Is_Private_Type (Btype) then
452 Utyp : constant Entity_Id := Underlying_Type (Btype);
457 return Is_By_Reference_Type (Utyp);
461 elsif Is_Incomplete_Type (Btype) then
463 Ftyp : constant Entity_Id := Full_View (Btype);
468 return Is_By_Reference_Type (Ftyp);
472 elsif Is_Concurrent_Type (Btype) then
475 elsif Is_Record_Type (Btype) then
476 if Is_Limited_Record (Btype)
477 or else Is_Tagged_Type (Btype)
478 or else Is_Volatile (Btype)
487 C := First_Component (Btype);
488 while Present (C) loop
489 if Is_By_Reference_Type (Etype (C))
490 or else Is_Volatile (Etype (C))
495 C := Next_Component (C);
502 elsif Is_Array_Type (Btype) then
505 or else Is_By_Reference_Type (Component_Type (Btype))
506 or else Is_Volatile (Component_Type (Btype))
507 or else Has_Volatile_Components (Btype);
512 end Is_By_Reference_Type;
514 ---------------------
515 -- Is_Derived_Type --
516 ---------------------
518 function Is_Derived_Type (Ent : E) return B is
523 and then Base_Type (Ent) /= Root_Type (Ent)
524 and then not Is_Class_Wide_Type (Ent)
526 if not Is_Numeric_Type (Root_Type (Ent)) then
530 Par := Parent (First_Subtype (Ent));
533 and then Nkind (Par) = N_Full_Type_Declaration
534 and then Nkind (Type_Definition (Par)) =
535 N_Derived_Type_Definition;
543 ---------------------------
544 -- Is_Indefinite_Subtype --
545 ---------------------------
547 function Is_Indefinite_Subtype (Ent : Entity_Id) return Boolean is
548 K : constant Entity_Kind := Ekind (Ent);
551 if Is_Constrained (Ent) then
554 elsif K in Array_Kind
555 or else K in Class_Wide_Kind
556 or else Has_Unknown_Discriminants (Ent)
560 -- Known discriminants: indefinite if there are no default values
562 elsif K in Record_Kind
563 or else Is_Incomplete_Or_Private_Type (Ent)
564 or else Is_Concurrent_Type (Ent)
566 return (Has_Discriminants (Ent)
568 No (Discriminant_Default_Value (First_Discriminant (Ent))));
573 end Is_Indefinite_Subtype;
575 --------------------------------
576 -- Is_Inherently_Limited_Type --
577 --------------------------------
579 function Is_Inherently_Limited_Type (Ent : Entity_Id) return Boolean is
580 Btype : constant Entity_Id := Base_Type (Ent);
583 if Is_Private_Type (Btype) then
585 Utyp : constant Entity_Id := Underlying_Type (Btype);
590 return Is_Inherently_Limited_Type (Utyp);
594 elsif Is_Concurrent_Type (Btype) then
597 elsif Is_Record_Type (Btype) then
598 if Is_Limited_Record (Btype) then
599 return not Is_Interface (Btype)
600 or else Is_Protected_Interface (Btype)
601 or else Is_Synchronized_Interface (Btype)
602 or else Is_Task_Interface (Btype);
604 elsif Is_Class_Wide_Type (Btype) then
605 return Is_Inherently_Limited_Type (Root_Type (Btype));
612 C := First_Component (Btype);
613 while Present (C) loop
614 if Is_Inherently_Limited_Type (Etype (C)) then
618 C := Next_Component (C);
625 elsif Is_Array_Type (Btype) then
626 return Is_Inherently_Limited_Type (Component_Type (Btype));
631 end Is_Inherently_Limited_Type;
633 ---------------------
634 -- Is_Limited_Type --
635 ---------------------
637 function Is_Limited_Type (Ent : Entity_Id) return Boolean is
638 Btype : constant E := Base_Type (Ent);
639 Rtype : constant E := Root_Type (Btype);
642 if not Is_Type (Ent) then
645 elsif Ekind (Btype) = E_Limited_Private_Type
646 or else Is_Limited_Composite (Btype)
650 elsif Is_Concurrent_Type (Btype) then
653 -- The Is_Limited_Record flag normally indicates that the type is
654 -- limited. The exception is that a type does not inherit limitedness
655 -- from its interface ancestor. So the type may be derived from a
656 -- limited interface, but is not limited.
658 elsif Is_Limited_Record (Ent)
659 and then not Is_Interface (Ent)
663 -- Otherwise we will look around to see if there is some other reason
664 -- for it to be limited, except that if an error was posted on the
665 -- entity, then just assume it is non-limited, because it can cause
666 -- trouble to recurse into a murky erroneous entity!
668 elsif Error_Posted (Ent) then
671 elsif Is_Record_Type (Btype) then
673 if Is_Limited_Interface (Ent) then
676 -- AI-419: limitedness is not inherited from a limited interface
678 elsif Is_Limited_Record (Rtype) then
679 return not Is_Interface (Rtype)
680 or else Is_Protected_Interface (Rtype)
681 or else Is_Synchronized_Interface (Rtype)
682 or else Is_Task_Interface (Rtype);
684 elsif Is_Class_Wide_Type (Btype) then
685 return Is_Limited_Type (Rtype);
692 C := First_Component (Btype);
693 while Present (C) loop
694 if Is_Limited_Type (Etype (C)) then
698 C := Next_Component (C);
705 elsif Is_Array_Type (Btype) then
706 return Is_Limited_Type (Component_Type (Btype));
713 ---------------------------
714 -- Nearest_Dynamic_Scope --
715 ---------------------------
717 function Nearest_Dynamic_Scope (Ent : Entity_Id) return Entity_Id is
719 if Is_Dynamic_Scope (Ent) then
722 return Enclosing_Dynamic_Scope (Ent);
724 end Nearest_Dynamic_Scope;
726 ------------------------
727 -- Next_Tag_Component --
728 ------------------------
730 function Next_Tag_Component (Tag : Entity_Id) return Entity_Id is
734 pragma Assert (Is_Tag (Tag));
736 -- Loop to look for next tag component
738 Comp := Next_Entity (Tag);
739 while Present (Comp) loop
740 if Is_Tag (Comp) then
741 pragma Assert (Chars (Comp) /= Name_uTag);
745 Comp := Next_Entity (Comp);
748 -- No tag component found
751 end Next_Tag_Component;
753 --------------------------
754 -- Number_Discriminants --
755 --------------------------
757 function Number_Discriminants (Typ : Entity_Id) return Pos is
763 Discr := First_Discriminant (Typ);
764 while Present (Discr) loop
766 Discr := Next_Discriminant (Discr);
770 end Number_Discriminants;
776 procedure Tree_Read is
778 Obsolescent_Warnings.Tree_Read;
785 procedure Tree_Write is
787 Obsolescent_Warnings.Tree_Write;