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 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Debug; use Debug;
28 with Elists; use Elists;
29 with Einfo; use Einfo;
30 with Exp_Disp; use Exp_Disp;
31 with Exp_Util; use Exp_Util;
32 with Exp_Ch7; use Exp_Ch7;
33 with Exp_Tss; use Exp_Tss;
34 with Errout; use Errout;
35 with Lib.Xref; use Lib.Xref;
36 with Namet; use Namet;
37 with Nlists; use Nlists;
38 with Nmake; use Nmake;
40 with Output; use Output;
41 with Restrict; use Restrict;
42 with Rident; use Rident;
44 with Sem_Aux; use Sem_Aux;
45 with Sem_Ch3; use Sem_Ch3;
46 with Sem_Ch6; use Sem_Ch6;
47 with Sem_Eval; use Sem_Eval;
48 with Sem_Type; use Sem_Type;
49 with Sem_Util; use Sem_Util;
50 with Snames; use Snames;
51 with Sinfo; use Sinfo;
52 with Targparm; use Targparm;
53 with Tbuild; use Tbuild;
54 with Uintp; use Uintp;
56 package body Sem_Disp is
58 -----------------------
59 -- Local Subprograms --
60 -----------------------
62 procedure Add_Dispatching_Operation
63 (Tagged_Type : Entity_Id;
65 -- Add New_Op in the list of primitive operations of Tagged_Type
67 function Check_Controlling_Type
69 Subp : Entity_Id) return Entity_Id;
70 -- T is the tagged type of a formal parameter or the result of Subp.
71 -- If the subprogram has a controlling parameter or result that matches
72 -- the type, then returns the tagged type of that parameter or result
73 -- (returning the designated tagged type in the case of an access
74 -- parameter); otherwise returns empty.
76 function Find_Hidden_Overridden_Primitive (S : Entity_Id) return Entity_Id;
77 -- [Ada 2012:AI-0125] Find an inherited hidden primitive of the dispatching
78 -- type of S that has the same name of S, a type-conformant profile, an
79 -- original corresponding operation O that is a primitive of a visible
80 -- ancestor of the dispatching type of S and O is visible at the point of
81 -- of declaration of S. If the entity is found the Alias of S is set to the
82 -- original corresponding operation S and its Overridden_Operation is set
83 -- to the found entity; otherwise return Empty.
85 -- This routine does not search for non-hidden primitives since they are
86 -- covered by the normal Ada 2005 rules.
88 -------------------------------
89 -- Add_Dispatching_Operation --
90 -------------------------------
92 procedure Add_Dispatching_Operation
93 (Tagged_Type : Entity_Id;
96 List : constant Elist_Id := Primitive_Operations (Tagged_Type);
99 -- The dispatching operation may already be on the list, if it is the
100 -- wrapper for an inherited function of a null extension (see Exp_Ch3
101 -- for the construction of function wrappers). The list of primitive
102 -- operations must not contain duplicates.
104 Append_Unique_Elmt (New_Op, List);
105 end Add_Dispatching_Operation;
107 ---------------------------
108 -- Covers_Some_Interface --
109 ---------------------------
111 function Covers_Some_Interface (Prim : Entity_Id) return Boolean is
112 Tagged_Type : constant Entity_Id := Find_Dispatching_Type (Prim);
117 pragma Assert (Is_Dispatching_Operation (Prim));
119 -- Although this is a dispatching primitive we must check if its
120 -- dispatching type is available because it may be the primitive
121 -- of a private type not defined as tagged in its partial view.
123 if Present (Tagged_Type) and then Has_Interfaces (Tagged_Type) then
125 -- If the tagged type is frozen then the internal entities associated
126 -- with interfaces are available in the list of primitives of the
127 -- tagged type and can be used to speed up this search.
129 if Is_Frozen (Tagged_Type) then
130 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
131 while Present (Elmt) loop
134 if Present (Interface_Alias (E))
135 and then Alias (E) = Prim
143 -- Otherwise we must collect all the interface primitives and check
144 -- if the Prim will override some interface primitive.
148 Ifaces_List : Elist_Id;
149 Iface_Elmt : Elmt_Id;
151 Iface_Prim : Entity_Id;
154 Collect_Interfaces (Tagged_Type, Ifaces_List);
155 Iface_Elmt := First_Elmt (Ifaces_List);
156 while Present (Iface_Elmt) loop
157 Iface := Node (Iface_Elmt);
159 Elmt := First_Elmt (Primitive_Operations (Iface));
160 while Present (Elmt) loop
161 Iface_Prim := Node (Elmt);
163 if Chars (Iface) = Chars (Prim)
164 and then Is_Interface_Conformant
165 (Tagged_Type, Iface_Prim, Prim)
173 Next_Elmt (Iface_Elmt);
180 end Covers_Some_Interface;
182 -------------------------------
183 -- Check_Controlling_Formals --
184 -------------------------------
186 procedure Check_Controlling_Formals
191 Ctrl_Type : Entity_Id;
194 Formal := First_Formal (Subp);
195 while Present (Formal) loop
196 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
198 if Present (Ctrl_Type) then
200 -- When controlling type is concurrent and declared within a
201 -- generic or inside an instance use corresponding record type.
203 if Is_Concurrent_Type (Ctrl_Type)
204 and then Present (Corresponding_Record_Type (Ctrl_Type))
206 Ctrl_Type := Corresponding_Record_Type (Ctrl_Type);
209 if Ctrl_Type = Typ then
210 Set_Is_Controlling_Formal (Formal);
212 -- Ada 2005 (AI-231): Anonymous access types that are used in
213 -- controlling parameters exclude null because it is necessary
214 -- to read the tag to dispatch, and null has no tag.
216 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
217 Set_Can_Never_Be_Null (Etype (Formal));
218 Set_Is_Known_Non_Null (Etype (Formal));
221 -- Check that the parameter's nominal subtype statically
222 -- matches the first subtype.
224 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
225 if not Subtypes_Statically_Match
226 (Typ, Designated_Type (Etype (Formal)))
229 ("parameter subtype does not match controlling type",
233 elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then
235 ("parameter subtype does not match controlling type",
239 if Present (Default_Value (Formal)) then
241 -- In Ada 2005, access parameters can have defaults
243 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
244 and then Ada_Version < Ada_2005
247 ("default not allowed for controlling access parameter",
248 Default_Value (Formal));
250 elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then
252 ("default expression must be a tag indeterminate" &
253 " function call", Default_Value (Formal));
257 elsif Comes_From_Source (Subp) then
259 ("operation can be dispatching in only one type", Subp);
263 Next_Formal (Formal);
266 if Ekind_In (Subp, E_Function, E_Generic_Function) then
267 Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp);
269 if Present (Ctrl_Type) then
270 if Ctrl_Type = Typ then
271 Set_Has_Controlling_Result (Subp);
273 -- Check that result subtype statically matches first subtype
274 -- (Ada 2005): Subp may have a controlling access result.
276 if Subtypes_Statically_Match (Typ, Etype (Subp))
277 or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type
279 Subtypes_Statically_Match
280 (Typ, Designated_Type (Etype (Subp))))
286 ("result subtype does not match controlling type", Subp);
289 elsif Comes_From_Source (Subp) then
291 ("operation can be dispatching in only one type", Subp);
295 end Check_Controlling_Formals;
297 ----------------------------
298 -- Check_Controlling_Type --
299 ----------------------------
301 function Check_Controlling_Type
303 Subp : Entity_Id) return Entity_Id
305 Tagged_Type : Entity_Id := Empty;
308 if Is_Tagged_Type (T) then
309 if Is_First_Subtype (T) then
312 Tagged_Type := Base_Type (T);
315 elsif Ekind (T) = E_Anonymous_Access_Type
316 and then Is_Tagged_Type (Designated_Type (T))
318 if Ekind (Designated_Type (T)) /= E_Incomplete_Type then
319 if Is_First_Subtype (Designated_Type (T)) then
320 Tagged_Type := Designated_Type (T);
322 Tagged_Type := Base_Type (Designated_Type (T));
325 -- Ada 2005: an incomplete type can be tagged. An operation with an
326 -- access parameter of the type is dispatching.
328 elsif Scope (Designated_Type (T)) = Current_Scope then
329 Tagged_Type := Designated_Type (T);
331 -- Ada 2005 (AI-50217)
333 elsif From_With_Type (Designated_Type (T))
334 and then Present (Non_Limited_View (Designated_Type (T)))
336 if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then
337 Tagged_Type := Non_Limited_View (Designated_Type (T));
339 Tagged_Type := Base_Type (Non_Limited_View
340 (Designated_Type (T)));
345 if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then
348 -- The dispatching type and the primitive operation must be defined in
349 -- the same scope, except in the case of internal operations and formal
350 -- abstract subprograms.
352 elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp))
353 and then (not Is_Generic_Type (Tagged_Type)
354 or else not Comes_From_Source (Subp)))
356 (Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp))
358 (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration
360 Present (Corresponding_Formal_Spec (Parent (Parent (Subp))))
362 Is_Abstract_Subprogram (Subp))
369 end Check_Controlling_Type;
371 ----------------------------
372 -- Check_Dispatching_Call --
373 ----------------------------
375 procedure Check_Dispatching_Call (N : Node_Id) is
376 Loc : constant Source_Ptr := Sloc (N);
379 Control : Node_Id := Empty;
381 Subp_Entity : Entity_Id;
382 Indeterm_Ancestor_Call : Boolean := False;
383 Indeterm_Ctrl_Type : Entity_Id;
385 Static_Tag : Node_Id := Empty;
386 -- If a controlling formal has a statically tagged actual, the tag of
387 -- this actual is to be used for any tag-indeterminate actual.
389 procedure Check_Direct_Call;
390 -- In the case when the controlling actual is a class-wide type whose
391 -- root type's completion is a task or protected type, the call is in
392 -- fact direct. This routine detects the above case and modifies the
395 procedure Check_Dispatching_Context;
396 -- If the call is tag-indeterminate and the entity being called is
397 -- abstract, verify that the context is a call that will eventually
398 -- provide a tag for dispatching, or has provided one already.
400 -----------------------
401 -- Check_Direct_Call --
402 -----------------------
404 procedure Check_Direct_Call is
405 Typ : Entity_Id := Etype (Control);
407 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean;
408 -- Determine whether an entity denotes a user-defined equality
410 ------------------------------
411 -- Is_User_Defined_Equality --
412 ------------------------------
414 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is
417 Ekind (Id) = E_Function
418 and then Chars (Id) = Name_Op_Eq
419 and then Comes_From_Source (Id)
421 -- Internally generated equalities have a full type declaration
424 and then Nkind (Parent (Id)) = N_Function_Specification;
425 end Is_User_Defined_Equality;
427 -- Start of processing for Check_Direct_Call
430 -- Predefined primitives do not receive wrappers since they are built
431 -- from scratch for the corresponding record of synchronized types.
432 -- Equality is in general predefined, but is excluded from the check
433 -- when it is user-defined.
435 if Is_Predefined_Dispatching_Operation (Subp_Entity)
436 and then not Is_User_Defined_Equality (Subp_Entity)
441 if Is_Class_Wide_Type (Typ) then
442 Typ := Root_Type (Typ);
445 if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
446 Typ := Full_View (Typ);
449 if Is_Concurrent_Type (Typ)
451 Present (Corresponding_Record_Type (Typ))
453 Typ := Corresponding_Record_Type (Typ);
455 -- The concurrent record's list of primitives should contain a
456 -- wrapper for the entity of the call, retrieve it.
461 Wrapper_Found : Boolean := False;
464 Prim_Elmt := First_Elmt (Primitive_Operations (Typ));
465 while Present (Prim_Elmt) loop
466 Prim := Node (Prim_Elmt);
468 if Is_Primitive_Wrapper (Prim)
469 and then Wrapped_Entity (Prim) = Subp_Entity
471 Wrapper_Found := True;
475 Next_Elmt (Prim_Elmt);
478 -- A primitive declared between two views should have a
479 -- corresponding wrapper.
481 pragma Assert (Wrapper_Found);
483 -- Modify the call by setting the proper entity
485 Set_Entity (Name (N), Prim);
488 end Check_Direct_Call;
490 -------------------------------
491 -- Check_Dispatching_Context --
492 -------------------------------
494 procedure Check_Dispatching_Context is
495 Subp : constant Entity_Id := Entity (Name (N));
499 if Is_Abstract_Subprogram (Subp)
500 and then No (Controlling_Argument (N))
502 if Present (Alias (Subp))
503 and then not Is_Abstract_Subprogram (Alias (Subp))
504 and then No (DTC_Entity (Subp))
506 -- Private overriding of inherited abstract operation, call is
509 Set_Entity (Name (N), Alias (Subp));
514 while Present (Par) loop
515 if Nkind_In (Par, N_Function_Call,
516 N_Procedure_Call_Statement,
517 N_Assignment_Statement,
520 and then Is_Tagged_Type (Etype (Subp))
524 elsif Nkind (Par) = N_Qualified_Expression
525 or else Nkind (Par) = N_Unchecked_Type_Conversion
530 if Ekind (Subp) = E_Function then
532 ("call to abstract function must be dispatching", N);
534 -- This error can occur for a procedure in the case of a
535 -- call to an abstract formal procedure with a statically
540 ("call to abstract procedure must be dispatching",
549 end Check_Dispatching_Context;
551 -- Start of processing for Check_Dispatching_Call
554 -- Find a controlling argument, if any
556 if Present (Parameter_Associations (N)) then
557 Subp_Entity := Entity (Name (N));
559 Actual := First_Actual (N);
560 Formal := First_Formal (Subp_Entity);
561 while Present (Actual) loop
562 Control := Find_Controlling_Arg (Actual);
563 exit when Present (Control);
565 -- Check for the case where the actual is a tag-indeterminate call
566 -- whose result type is different than the tagged type associated
567 -- with the containing call, but is an ancestor of the type.
569 if Is_Controlling_Formal (Formal)
570 and then Is_Tag_Indeterminate (Actual)
571 and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal))
572 and then Is_Ancestor (Etype (Actual), Etype (Formal))
574 Indeterm_Ancestor_Call := True;
575 Indeterm_Ctrl_Type := Etype (Formal);
577 -- If the formal is controlling but the actual is not, the type
578 -- of the actual is statically known, and may be used as the
579 -- controlling tag for some other tag-indeterminate actual.
581 elsif Is_Controlling_Formal (Formal)
582 and then Is_Entity_Name (Actual)
583 and then Is_Tagged_Type (Etype (Actual))
585 Static_Tag := Actual;
588 Next_Actual (Actual);
589 Next_Formal (Formal);
592 -- If the call doesn't have a controlling actual but does have an
593 -- indeterminate actual that requires dispatching treatment, then an
594 -- object is needed that will serve as the controlling argument for a
595 -- dispatching call on the indeterminate actual. This can only occur
596 -- in the unusual situation of a default actual given by a
597 -- tag-indeterminate call and where the type of the call is an
598 -- ancestor of the type associated with a containing call to an
599 -- inherited operation (see AI-239).
601 -- Rather than create an object of the tagged type, which would be
602 -- problematic for various reasons (default initialization,
603 -- discriminants), the tag of the containing call's associated tagged
604 -- type is directly used to control the dispatching.
607 and then Indeterm_Ancestor_Call
608 and then No (Static_Tag)
611 Make_Attribute_Reference (Loc,
612 Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc),
613 Attribute_Name => Name_Tag);
618 if Present (Control) then
620 -- Verify that no controlling arguments are statically tagged
623 Write_Str ("Found Dispatching call");
628 Actual := First_Actual (N);
629 while Present (Actual) loop
630 if Actual /= Control then
632 if not Is_Controlling_Actual (Actual) then
633 null; -- Can be anything
635 elsif Is_Dynamically_Tagged (Actual) then
636 null; -- Valid parameter
638 elsif Is_Tag_Indeterminate (Actual) then
640 -- The tag is inherited from the enclosing call (the node
641 -- we are currently analyzing). Explicitly expand the
642 -- actual, since the previous call to Expand (from
643 -- Resolve_Call) had no way of knowing about the required
646 Propagate_Tag (Control, Actual);
650 ("controlling argument is not dynamically tagged",
656 Next_Actual (Actual);
659 -- Mark call as a dispatching call
661 Set_Controlling_Argument (N, Control);
662 Check_Restriction (No_Dispatching_Calls, N);
664 -- The dispatching call may need to be converted into a direct
665 -- call in certain cases.
669 -- If there is a statically tagged actual and a tag-indeterminate
670 -- call to a function of the ancestor (such as that provided by a
671 -- default), then treat this as a dispatching call and propagate
672 -- the tag to the tag-indeterminate call(s).
674 elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then
676 Make_Attribute_Reference (Loc,
678 New_Occurrence_Of (Etype (Static_Tag), Loc),
679 Attribute_Name => Name_Tag);
683 Actual := First_Actual (N);
684 Formal := First_Formal (Subp_Entity);
685 while Present (Actual) loop
686 if Is_Tag_Indeterminate (Actual)
687 and then Is_Controlling_Formal (Formal)
689 Propagate_Tag (Control, Actual);
692 Next_Actual (Actual);
693 Next_Formal (Formal);
696 Check_Dispatching_Context;
699 -- The call is not dispatching, so check that there aren't any
700 -- tag-indeterminate abstract calls left.
702 Actual := First_Actual (N);
703 while Present (Actual) loop
704 if Is_Tag_Indeterminate (Actual) then
706 -- Function call case
708 if Nkind (Original_Node (Actual)) = N_Function_Call then
709 Func := Entity (Name (Original_Node (Actual)));
711 -- If the actual is an attribute then it can't be abstract
712 -- (the only current case of a tag-indeterminate attribute
713 -- is the stream Input attribute).
716 Nkind (Original_Node (Actual)) = N_Attribute_Reference
720 -- Only other possibility is a qualified expression whose
721 -- constituent expression is itself a call.
727 (Expression (Original_Node (Actual)))));
730 if Present (Func) and then Is_Abstract_Subprogram (Func) then
732 ("call to abstract function must be dispatching", N);
736 Next_Actual (Actual);
739 Check_Dispatching_Context;
743 -- If dispatching on result, the enclosing call, if any, will
744 -- determine the controlling argument. Otherwise this is the
745 -- primitive operation of the root type.
747 Check_Dispatching_Context;
749 end Check_Dispatching_Call;
751 ---------------------------------
752 -- Check_Dispatching_Operation --
753 ---------------------------------
755 procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id) is
756 Tagged_Type : Entity_Id;
757 Has_Dispatching_Parent : Boolean := False;
758 Body_Is_Last_Primitive : Boolean := False;
759 Ovr_Subp : Entity_Id := Empty;
762 if not Ekind_In (Subp, E_Procedure, E_Function) then
766 Set_Is_Dispatching_Operation (Subp, False);
767 Tagged_Type := Find_Dispatching_Type (Subp);
769 -- Ada 2005 (AI-345): Use the corresponding record (if available).
770 -- Required because primitives of concurrent types are be attached
771 -- to the corresponding record (not to the concurrent type).
773 if Ada_Version >= Ada_2005
774 and then Present (Tagged_Type)
775 and then Is_Concurrent_Type (Tagged_Type)
776 and then Present (Corresponding_Record_Type (Tagged_Type))
778 Tagged_Type := Corresponding_Record_Type (Tagged_Type);
781 -- (AI-345): The task body procedure is not a primitive of the tagged
784 if Present (Tagged_Type)
785 and then Is_Concurrent_Record_Type (Tagged_Type)
786 and then Present (Corresponding_Concurrent_Type (Tagged_Type))
787 and then Is_Task_Type (Corresponding_Concurrent_Type (Tagged_Type))
788 and then Subp = Get_Task_Body_Procedure
789 (Corresponding_Concurrent_Type (Tagged_Type))
794 -- If Subp is derived from a dispatching operation then it should
795 -- always be treated as dispatching. In this case various checks
796 -- below will be bypassed. Makes sure that late declarations for
797 -- inherited private subprograms are treated as dispatching, even
798 -- if the associated tagged type is already frozen.
800 Has_Dispatching_Parent :=
801 Present (Alias (Subp))
802 and then Is_Dispatching_Operation (Alias (Subp));
804 if No (Tagged_Type) then
806 -- Ada 2005 (AI-251): Check that Subp is not a primitive associated
807 -- with an abstract interface type unless the interface acts as a
808 -- parent type in a derivation. If the interface type is a formal
809 -- type then the operation is not primitive and therefore legal.
816 E := First_Entity (Subp);
817 while Present (E) loop
819 -- For an access parameter, check designated type
821 if Ekind (Etype (E)) = E_Anonymous_Access_Type then
822 Typ := Designated_Type (Etype (E));
827 if Comes_From_Source (Subp)
828 and then Is_Interface (Typ)
829 and then not Is_Class_Wide_Type (Typ)
830 and then not Is_Derived_Type (Typ)
831 and then not Is_Generic_Type (Typ)
832 and then not In_Instance
834 Error_Msg_N ("?declaration of& is too late!", Subp);
835 Error_Msg_NE -- CODEFIX??
836 ("\spec should appear immediately after declaration of &!",
844 -- In case of functions check also the result type
846 if Ekind (Subp) = E_Function then
847 if Is_Access_Type (Etype (Subp)) then
848 Typ := Designated_Type (Etype (Subp));
853 -- The following should be better commented, especially since
854 -- we just added several new conditions here ???
856 if Comes_From_Source (Subp)
857 and then Is_Interface (Typ)
858 and then not Is_Class_Wide_Type (Typ)
859 and then not Is_Derived_Type (Typ)
860 and then not Is_Generic_Type (Typ)
861 and then not In_Instance
863 Error_Msg_N ("?declaration of& is too late!", Subp);
865 ("\spec should appear immediately after declaration of &!",
873 -- The subprograms build internally after the freezing point (such as
874 -- init procs, interface thunks, type support subprograms, and Offset
875 -- to top functions for accessing interface components in variable
876 -- size tagged types) are not primitives.
878 elsif Is_Frozen (Tagged_Type)
879 and then not Comes_From_Source (Subp)
880 and then not Has_Dispatching_Parent
882 -- Complete decoration of internally built subprograms that override
883 -- a dispatching primitive. These entities correspond with the
886 -- 1. Ada 2005 (AI-391): Wrapper functions built by the expander
887 -- to override functions of nonabstract null extensions. These
888 -- primitives were added to the list of primitives of the tagged
889 -- type by Make_Controlling_Function_Wrappers. However, attribute
890 -- Is_Dispatching_Operation must be set to true.
892 -- 2. Ada 2005 (AI-251): Wrapper procedures of null interface
895 -- 3. Subprograms associated with stream attributes (built by
896 -- New_Stream_Subprogram)
898 if Present (Old_Subp)
899 and then Present (Overridden_Operation (Subp))
900 and then Is_Dispatching_Operation (Old_Subp)
903 ((Ekind (Subp) = E_Function
904 and then Is_Dispatching_Operation (Old_Subp)
905 and then Is_Null_Extension (Base_Type (Etype (Subp))))
907 (Ekind (Subp) = E_Procedure
908 and then Is_Dispatching_Operation (Old_Subp)
909 and then Present (Alias (Old_Subp))
910 and then Is_Null_Interface_Primitive
911 (Ultimate_Alias (Old_Subp)))
912 or else Get_TSS_Name (Subp) = TSS_Stream_Read
913 or else Get_TSS_Name (Subp) = TSS_Stream_Write);
915 Check_Controlling_Formals (Tagged_Type, Subp);
916 Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp);
917 Set_Is_Dispatching_Operation (Subp);
922 -- The operation may be a child unit, whose scope is the defining
923 -- package, but which is not a primitive operation of the type.
925 elsif Is_Child_Unit (Subp) then
928 -- If the subprogram is not defined in a package spec, the only case
929 -- where it can be a dispatching op is when it overrides an operation
930 -- before the freezing point of the type.
932 elsif ((not Is_Package_Or_Generic_Package (Scope (Subp)))
933 or else In_Package_Body (Scope (Subp)))
934 and then not Has_Dispatching_Parent
936 if not Comes_From_Source (Subp)
937 or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type))
941 -- If the type is already frozen, the overriding is not allowed
942 -- except when Old_Subp is not a dispatching operation (which can
943 -- occur when Old_Subp was inherited by an untagged type). However,
944 -- a body with no previous spec freezes the type *after* its
945 -- declaration, and therefore is a legal overriding (unless the type
946 -- has already been frozen). Only the first such body is legal.
948 elsif Present (Old_Subp)
949 and then Is_Dispatching_Operation (Old_Subp)
951 if Comes_From_Source (Subp)
953 (Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body
954 or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub)
957 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
961 -- ??? The checks here for whether the type has been
962 -- frozen prior to the new body are not complete. It's
963 -- not simple to check frozenness at this point since
964 -- the body has already caused the type to be prematurely
965 -- frozen in Analyze_Declarations, but we're forced to
966 -- recheck this here because of the odd rule interpretation
967 -- that allows the overriding if the type wasn't frozen
968 -- prior to the body. The freezing action should probably
969 -- be delayed until after the spec is seen, but that's
970 -- a tricky change to the delicate freezing code.
972 -- Look at each declaration following the type up until the
973 -- new subprogram body. If any of the declarations is a body
974 -- then the type has been frozen already so the overriding
975 -- primitive is illegal.
977 Decl_Item := Next (Parent (Tagged_Type));
978 while Present (Decl_Item)
979 and then (Decl_Item /= Subp_Body)
981 if Comes_From_Source (Decl_Item)
982 and then (Nkind (Decl_Item) in N_Proper_Body
983 or else Nkind (Decl_Item) in N_Body_Stub)
985 Error_Msg_N ("overriding of& is too late!", Subp);
987 ("\spec should appear immediately after the type!",
995 -- If the subprogram doesn't follow in the list of
996 -- declarations including the type then the type has
997 -- definitely been frozen already and the body is illegal.
999 if No (Decl_Item) then
1000 Error_Msg_N ("overriding of& is too late!", Subp);
1002 ("\spec should appear immediately after the type!",
1005 elsif Is_Frozen (Subp) then
1007 -- The subprogram body declares a primitive operation.
1008 -- if the subprogram is already frozen, we must update
1009 -- its dispatching information explicitly here. The
1010 -- information is taken from the overridden subprogram.
1011 -- We must also generate a cross-reference entry because
1012 -- references to other primitives were already created
1013 -- when type was frozen.
1015 Body_Is_Last_Primitive := True;
1017 if Present (DTC_Entity (Old_Subp)) then
1018 Set_DTC_Entity (Subp, DTC_Entity (Old_Subp));
1019 Set_DT_Position (Subp, DT_Position (Old_Subp));
1021 if not Restriction_Active (No_Dispatching_Calls) then
1022 if Building_Static_DT (Tagged_Type) then
1024 -- If the static dispatch table has not been
1025 -- built then there is nothing else to do now;
1026 -- otherwise we notify that we cannot build the
1027 -- static dispatch table.
1029 if Has_Dispatch_Table (Tagged_Type) then
1031 ("overriding of& is too late for building" &
1032 " static dispatch tables!", Subp);
1034 ("\spec should appear immediately after" &
1035 " the type!", Subp);
1038 -- No code required to register primitives in VM
1041 elsif VM_Target /= No_VM then
1045 Insert_Actions_After (Subp_Body,
1046 Register_Primitive (Sloc (Subp_Body),
1050 -- Indicate that this is an overriding operation,
1051 -- and replace the overridden entry in the list of
1052 -- primitive operations, which is used for xref
1053 -- generation subsequently.
1055 Generate_Reference (Tagged_Type, Subp, 'P', False);
1056 Override_Dispatching_Operation
1057 (Tagged_Type, Old_Subp, Subp);
1064 Error_Msg_N ("overriding of& is too late!", Subp);
1066 ("\subprogram spec should appear immediately after the type!",
1070 -- If the type is not frozen yet and we are not in the overriding
1071 -- case it looks suspiciously like an attempt to define a primitive
1072 -- operation, which requires the declaration to be in a package spec
1073 -- (3.2.3(6)). Only report cases where the type and subprogram are
1074 -- in the same declaration list (by checking the enclosing parent
1075 -- declarations), to avoid spurious warnings on subprograms in
1076 -- instance bodies when the type is declared in the instance spec but
1077 -- hasn't been frozen by the instance body.
1079 elsif not Is_Frozen (Tagged_Type)
1080 and then In_Same_List (Parent (Tagged_Type), Parent (Parent (Subp)))
1083 ("?not dispatching (must be defined in a package spec)", Subp);
1086 -- When the type is frozen, it is legitimate to define a new
1087 -- non-primitive operation.
1093 -- Now, we are sure that the scope is a package spec. If the subprogram
1094 -- is declared after the freezing point of the type that's an error
1096 elsif Is_Frozen (Tagged_Type) and then not Has_Dispatching_Parent then
1097 Error_Msg_N ("this primitive operation is declared too late", Subp);
1099 ("?no primitive operations for& after this line",
1100 Freeze_Node (Tagged_Type),
1105 Check_Controlling_Formals (Tagged_Type, Subp);
1107 Ovr_Subp := Old_Subp;
1109 -- [Ada 2012:AI-0125]: Search for inherited hidden primitive that may be
1110 -- overridden by Subp
1113 and then Ada_Version >= Ada_2012
1115 Ovr_Subp := Find_Hidden_Overridden_Primitive (Subp);
1118 -- Now it should be a correct primitive operation, put it in the list
1120 if Present (Ovr_Subp) then
1122 -- If the type has interfaces we complete this check after we set
1123 -- attribute Is_Dispatching_Operation.
1125 Check_Subtype_Conformant (Subp, Ovr_Subp);
1127 if (Chars (Subp) = Name_Initialize
1128 or else Chars (Subp) = Name_Adjust
1129 or else Chars (Subp) = Name_Finalize)
1130 and then Is_Controlled (Tagged_Type)
1131 and then not Is_Visibly_Controlled (Tagged_Type)
1133 Set_Overridden_Operation (Subp, Empty);
1135 -- If the subprogram specification carries an overriding
1136 -- indicator, no need for the warning: it is either redundant,
1137 -- or else an error will be reported.
1139 if Nkind (Parent (Subp)) = N_Procedure_Specification
1141 (Must_Override (Parent (Subp))
1142 or else Must_Not_Override (Parent (Subp)))
1146 -- Here we need the warning
1150 ("operation does not override inherited&?", Subp, Subp);
1154 Override_Dispatching_Operation (Tagged_Type, Ovr_Subp, Subp);
1156 -- Ada 2005 (AI-251): In case of late overriding of a primitive
1157 -- that covers abstract interface subprograms we must register it
1158 -- in all the secondary dispatch tables associated with abstract
1159 -- interfaces. We do this now only if not building static tables,
1160 -- nor when the expander is inactive (we avoid trying to register
1161 -- primitives in semantics-only mode, since the type may not have
1162 -- an associated dispatch table). Otherwise the patch code is
1163 -- emitted after those tables are built, to prevent access before
1164 -- elaboration in gigi.
1166 if Body_Is_Last_Primitive and then Full_Expander_Active then
1168 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
1173 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1174 while Present (Elmt) loop
1175 Prim := Node (Elmt);
1177 -- No code required to register primitives in VM targets
1179 if Present (Alias (Prim))
1180 and then Present (Interface_Alias (Prim))
1181 and then Alias (Prim) = Subp
1182 and then not Building_Static_DT (Tagged_Type)
1183 and then VM_Target = No_VM
1185 Insert_Actions_After (Subp_Body,
1186 Register_Primitive (Sloc (Subp_Body), Prim => Prim));
1192 -- Redisplay the contents of the updated dispatch table
1194 if Debug_Flag_ZZ then
1195 Write_Str ("Late overriding: ");
1196 Write_DT (Tagged_Type);
1202 -- If the tagged type is a concurrent type then we must be compiling
1203 -- with no code generation (we are either compiling a generic unit or
1204 -- compiling under -gnatc mode) because we have previously tested that
1205 -- no serious errors has been reported. In this case we do not add the
1206 -- primitive to the list of primitives of Tagged_Type but we leave the
1207 -- primitive decorated as a dispatching operation to be able to analyze
1208 -- and report errors associated with the Object.Operation notation.
1210 elsif Is_Concurrent_Type (Tagged_Type) then
1211 pragma Assert (not Expander_Active);
1214 -- If no old subprogram, then we add this as a dispatching operation,
1215 -- but we avoid doing this if an error was posted, to prevent annoying
1218 elsif not Error_Posted (Subp) then
1219 Add_Dispatching_Operation (Tagged_Type, Subp);
1222 Set_Is_Dispatching_Operation (Subp, True);
1224 -- Ada 2005 (AI-251): If the type implements interfaces we must check
1225 -- subtype conformance against all the interfaces covered by this
1228 if Present (Ovr_Subp)
1229 and then Has_Interfaces (Tagged_Type)
1232 Ifaces_List : Elist_Id;
1233 Iface_Elmt : Elmt_Id;
1234 Iface_Prim_Elmt : Elmt_Id;
1235 Iface_Prim : Entity_Id;
1236 Ret_Typ : Entity_Id;
1239 Collect_Interfaces (Tagged_Type, Ifaces_List);
1241 Iface_Elmt := First_Elmt (Ifaces_List);
1242 while Present (Iface_Elmt) loop
1243 if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then
1245 First_Elmt (Primitive_Operations (Node (Iface_Elmt)));
1246 while Present (Iface_Prim_Elmt) loop
1247 Iface_Prim := Node (Iface_Prim_Elmt);
1249 if Is_Interface_Conformant
1250 (Tagged_Type, Iface_Prim, Subp)
1252 -- Handle procedures, functions whose return type
1253 -- matches, or functions not returning interfaces
1255 if Ekind (Subp) = E_Procedure
1256 or else Etype (Iface_Prim) = Etype (Subp)
1257 or else not Is_Interface (Etype (Iface_Prim))
1259 Check_Subtype_Conformant
1261 Old_Id => Iface_Prim,
1263 Skip_Controlling_Formals => True);
1265 -- Handle functions returning interfaces
1267 elsif Implements_Interface
1268 (Etype (Subp), Etype (Iface_Prim))
1270 -- Temporarily force both entities to return the
1271 -- same type. Required because Subtype_Conformant
1272 -- does not handle this case.
1274 Ret_Typ := Etype (Iface_Prim);
1275 Set_Etype (Iface_Prim, Etype (Subp));
1277 Check_Subtype_Conformant
1279 Old_Id => Iface_Prim,
1281 Skip_Controlling_Formals => True);
1283 Set_Etype (Iface_Prim, Ret_Typ);
1287 Next_Elmt (Iface_Prim_Elmt);
1291 Next_Elmt (Iface_Elmt);
1296 if not Body_Is_Last_Primitive then
1297 Set_DT_Position (Subp, No_Uint);
1299 elsif Has_Controlled_Component (Tagged_Type)
1301 (Chars (Subp) = Name_Initialize or else
1302 Chars (Subp) = Name_Adjust or else
1303 Chars (Subp) = Name_Finalize or else
1304 Chars (Subp) = Name_Finalize_Address)
1307 F_Node : constant Node_Id := Freeze_Node (Tagged_Type);
1311 Old_Spec : Entity_Id;
1313 C_Names : constant array (1 .. 4) of Name_Id :=
1317 Name_Finalize_Address);
1319 D_Names : constant array (1 .. 4) of TSS_Name_Type :=
1320 (TSS_Deep_Initialize,
1323 TSS_Finalize_Address);
1326 -- Remove previous controlled function which was constructed and
1327 -- analyzed when the type was frozen. This requires removing the
1328 -- body of the redefined primitive, as well as its specification
1329 -- if needed (there is no spec created for Deep_Initialize, see
1330 -- exp_ch3.adb). We must also dismantle the exception information
1331 -- that may have been generated for it when front end zero-cost
1332 -- tables are enabled.
1334 for J in D_Names'Range loop
1335 Old_P := TSS (Tagged_Type, D_Names (J));
1338 and then Chars (Subp) = C_Names (J)
1340 Old_Bod := Unit_Declaration_Node (Old_P);
1342 Set_Is_Eliminated (Old_P);
1343 Set_Scope (Old_P, Scope (Current_Scope));
1345 if Nkind (Old_Bod) = N_Subprogram_Body
1346 and then Present (Corresponding_Spec (Old_Bod))
1348 Old_Spec := Corresponding_Spec (Old_Bod);
1349 Set_Has_Completion (Old_Spec, False);
1354 Build_Late_Proc (Tagged_Type, Chars (Subp));
1356 -- The new operation is added to the actions of the freeze node
1357 -- for the type, but this node has already been analyzed, so we
1358 -- must retrieve and analyze explicitly the new body.
1361 and then Present (Actions (F_Node))
1363 Decl := Last (Actions (F_Node));
1368 end Check_Dispatching_Operation;
1370 ------------------------------------------
1371 -- Check_Operation_From_Incomplete_Type --
1372 ------------------------------------------
1374 procedure Check_Operation_From_Incomplete_Type
1378 Full : constant Entity_Id := Full_View (Typ);
1379 Parent_Typ : constant Entity_Id := Etype (Full);
1380 Old_Prim : constant Elist_Id := Primitive_Operations (Parent_Typ);
1381 New_Prim : constant Elist_Id := Primitive_Operations (Full);
1383 Prev : Elmt_Id := No_Elmt;
1385 function Derives_From (Parent_Subp : Entity_Id) return Boolean;
1386 -- Check that Subp has profile of an operation derived from Parent_Subp.
1387 -- Subp must have a parameter or result type that is Typ or an access
1388 -- parameter or access result type that designates Typ.
1394 function Derives_From (Parent_Subp : Entity_Id) return Boolean is
1398 if Chars (Parent_Subp) /= Chars (Subp) then
1402 -- Check that the type of controlling formals is derived from the
1403 -- parent subprogram's controlling formal type (or designated type
1404 -- if the formal type is an anonymous access type).
1406 F1 := First_Formal (Parent_Subp);
1407 F2 := First_Formal (Subp);
1408 while Present (F1) and then Present (F2) loop
1409 if Ekind (Etype (F1)) = E_Anonymous_Access_Type then
1410 if Ekind (Etype (F2)) /= E_Anonymous_Access_Type then
1412 elsif Designated_Type (Etype (F1)) = Parent_Typ
1413 and then Designated_Type (Etype (F2)) /= Full
1418 elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then
1421 elsif Etype (F1) = Parent_Typ and then Etype (F2) /= Full then
1429 -- Check that a controlling result type is derived from the parent
1430 -- subprogram's result type (or designated type if the result type
1431 -- is an anonymous access type).
1433 if Ekind (Parent_Subp) = E_Function then
1434 if Ekind (Subp) /= E_Function then
1437 elsif Ekind (Etype (Parent_Subp)) = E_Anonymous_Access_Type then
1438 if Ekind (Etype (Subp)) /= E_Anonymous_Access_Type then
1441 elsif Designated_Type (Etype (Parent_Subp)) = Parent_Typ
1442 and then Designated_Type (Etype (Subp)) /= Full
1447 elsif Ekind (Etype (Subp)) = E_Anonymous_Access_Type then
1450 elsif Etype (Parent_Subp) = Parent_Typ
1451 and then Etype (Subp) /= Full
1456 elsif Ekind (Subp) = E_Function then
1460 return No (F1) and then No (F2);
1463 -- Start of processing for Check_Operation_From_Incomplete_Type
1466 -- The operation may override an inherited one, or may be a new one
1467 -- altogether. The inherited operation will have been hidden by the
1468 -- current one at the point of the type derivation, so it does not
1469 -- appear in the list of primitive operations of the type. We have to
1470 -- find the proper place of insertion in the list of primitive opera-
1471 -- tions by iterating over the list for the parent type.
1473 Op1 := First_Elmt (Old_Prim);
1474 Op2 := First_Elmt (New_Prim);
1475 while Present (Op1) and then Present (Op2) loop
1476 if Derives_From (Node (Op1)) then
1479 -- Avoid adding it to the list of primitives if already there!
1481 if Node (Op2) /= Subp then
1482 Prepend_Elmt (Subp, New_Prim);
1486 Insert_Elmt_After (Subp, Prev);
1497 -- Operation is a new primitive
1499 Append_Elmt (Subp, New_Prim);
1500 end Check_Operation_From_Incomplete_Type;
1502 ---------------------------------------
1503 -- Check_Operation_From_Private_View --
1504 ---------------------------------------
1506 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is
1507 Tagged_Type : Entity_Id;
1510 if Is_Dispatching_Operation (Alias (Subp)) then
1511 Set_Scope (Subp, Current_Scope);
1512 Tagged_Type := Find_Dispatching_Type (Subp);
1514 -- Add Old_Subp to primitive operations if not already present
1516 if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then
1517 Append_Unique_Elmt (Old_Subp, Primitive_Operations (Tagged_Type));
1519 -- If Old_Subp isn't already marked as dispatching then this is
1520 -- the case of an operation of an untagged private type fulfilled
1521 -- by a tagged type that overrides an inherited dispatching
1522 -- operation, so we set the necessary dispatching attributes here.
1524 if not Is_Dispatching_Operation (Old_Subp) then
1526 -- If the untagged type has no discriminants, and the full
1527 -- view is constrained, there will be a spurious mismatch of
1528 -- subtypes on the controlling arguments, because the tagged
1529 -- type is the internal base type introduced in the derivation.
1530 -- Use the original type to verify conformance, rather than the
1533 if not Comes_From_Source (Tagged_Type)
1534 and then Has_Discriminants (Tagged_Type)
1540 Formal := First_Formal (Old_Subp);
1541 while Present (Formal) loop
1542 if Tagged_Type = Base_Type (Etype (Formal)) then
1543 Tagged_Type := Etype (Formal);
1546 Next_Formal (Formal);
1550 if Tagged_Type = Base_Type (Etype (Old_Subp)) then
1551 Tagged_Type := Etype (Old_Subp);
1555 Check_Controlling_Formals (Tagged_Type, Old_Subp);
1556 Set_Is_Dispatching_Operation (Old_Subp, True);
1557 Set_DT_Position (Old_Subp, No_Uint);
1560 -- If the old subprogram is an explicit renaming of some other
1561 -- entity, it is not overridden by the inherited subprogram.
1562 -- Otherwise, update its alias and other attributes.
1564 if Present (Alias (Old_Subp))
1565 and then Nkind (Unit_Declaration_Node (Old_Subp)) /=
1566 N_Subprogram_Renaming_Declaration
1568 Set_Alias (Old_Subp, Alias (Subp));
1570 -- The derived subprogram should inherit the abstractness
1571 -- of the parent subprogram (except in the case of a function
1572 -- returning the type). This sets the abstractness properly
1573 -- for cases where a private extension may have inherited
1574 -- an abstract operation, but the full type is derived from
1575 -- a descendant type and inherits a nonabstract version.
1577 if Etype (Subp) /= Tagged_Type then
1578 Set_Is_Abstract_Subprogram
1579 (Old_Subp, Is_Abstract_Subprogram (Alias (Subp)));
1584 end Check_Operation_From_Private_View;
1586 --------------------------
1587 -- Find_Controlling_Arg --
1588 --------------------------
1590 function Find_Controlling_Arg (N : Node_Id) return Node_Id is
1591 Orig_Node : constant Node_Id := Original_Node (N);
1595 if Nkind (Orig_Node) = N_Qualified_Expression then
1596 return Find_Controlling_Arg (Expression (Orig_Node));
1599 -- Dispatching on result case. If expansion is disabled, the node still
1600 -- has the structure of a function call. However, if the function name
1601 -- is an operator and the call was given in infix form, the original
1602 -- node has no controlling result and we must examine the current node.
1604 if Nkind (N) = N_Function_Call
1605 and then Present (Controlling_Argument (N))
1606 and then Has_Controlling_Result (Entity (Name (N)))
1608 return Controlling_Argument (N);
1610 -- If expansion is enabled, the call may have been transformed into
1611 -- an indirect call, and we need to recover the original node.
1613 elsif Nkind (Orig_Node) = N_Function_Call
1614 and then Present (Controlling_Argument (Orig_Node))
1615 and then Has_Controlling_Result (Entity (Name (Orig_Node)))
1617 return Controlling_Argument (Orig_Node);
1619 -- Type conversions are dynamically tagged if the target type, or its
1620 -- designated type, are classwide. An interface conversion expands into
1621 -- a dereference, so test must be performed on the original node.
1623 elsif Nkind (Orig_Node) = N_Type_Conversion
1624 and then Nkind (N) = N_Explicit_Dereference
1625 and then Is_Controlling_Actual (N)
1628 Target_Type : constant Entity_Id :=
1629 Entity (Subtype_Mark (Orig_Node));
1632 if Is_Class_Wide_Type (Target_Type) then
1635 elsif Is_Access_Type (Target_Type)
1636 and then Is_Class_Wide_Type (Designated_Type (Target_Type))
1647 elsif Is_Controlling_Actual (N)
1649 (Nkind (Parent (N)) = N_Qualified_Expression
1650 and then Is_Controlling_Actual (Parent (N)))
1654 if Is_Access_Type (Typ) then
1656 -- In the case of an Access attribute, use the type of the prefix,
1657 -- since in the case of an actual for an access parameter, the
1658 -- attribute's type may be of a specific designated type, even
1659 -- though the prefix type is class-wide.
1661 if Nkind (N) = N_Attribute_Reference then
1662 Typ := Etype (Prefix (N));
1664 -- An allocator is dispatching if the type of qualified expression
1665 -- is class_wide, in which case this is the controlling type.
1667 elsif Nkind (Orig_Node) = N_Allocator
1668 and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression
1670 Typ := Etype (Expression (Orig_Node));
1672 Typ := Designated_Type (Typ);
1676 if Is_Class_Wide_Type (Typ)
1678 (Nkind (Parent (N)) = N_Qualified_Expression
1679 and then Is_Access_Type (Etype (N))
1680 and then Is_Class_Wide_Type (Designated_Type (Etype (N))))
1687 end Find_Controlling_Arg;
1689 ---------------------------
1690 -- Find_Dispatching_Type --
1691 ---------------------------
1693 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is
1694 A_Formal : Entity_Id;
1696 Ctrl_Type : Entity_Id;
1699 if Present (DTC_Entity (Subp)) then
1700 return Scope (DTC_Entity (Subp));
1702 -- For subprograms internally generated by derivations of tagged types
1703 -- use the alias subprogram as a reference to locate the dispatching
1706 elsif not Comes_From_Source (Subp)
1707 and then Present (Alias (Subp))
1708 and then Is_Dispatching_Operation (Alias (Subp))
1710 if Ekind (Alias (Subp)) = E_Function
1711 and then Has_Controlling_Result (Alias (Subp))
1713 return Check_Controlling_Type (Etype (Subp), Subp);
1716 Formal := First_Formal (Subp);
1717 A_Formal := First_Formal (Alias (Subp));
1718 while Present (A_Formal) loop
1719 if Is_Controlling_Formal (A_Formal) then
1720 return Check_Controlling_Type (Etype (Formal), Subp);
1723 Next_Formal (Formal);
1724 Next_Formal (A_Formal);
1727 pragma Assert (False);
1734 Formal := First_Formal (Subp);
1735 while Present (Formal) loop
1736 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
1738 if Present (Ctrl_Type) then
1742 Next_Formal (Formal);
1745 -- The subprogram may also be dispatching on result
1747 if Present (Etype (Subp)) then
1748 return Check_Controlling_Type (Etype (Subp), Subp);
1752 pragma Assert (not Is_Dispatching_Operation (Subp));
1754 end Find_Dispatching_Type;
1756 --------------------------------------
1757 -- Find_Hidden_Overridden_Primitive --
1758 --------------------------------------
1760 function Find_Hidden_Overridden_Primitive (S : Entity_Id) return Entity_Id
1762 Tag_Typ : constant Entity_Id := Find_Dispatching_Type (S);
1764 Orig_Prim : Entity_Id;
1766 Vis_List : Elist_Id;
1769 -- This Ada 2012 rule is valid only for type extensions or private
1773 or else not Is_Record_Type (Tag_Typ)
1774 or else Etype (Tag_Typ) = Tag_Typ
1779 -- Collect the list of visible ancestor of the tagged type
1781 Vis_List := Visible_Ancestors (Tag_Typ);
1783 Elmt := First_Elmt (Primitive_Operations (Tag_Typ));
1784 while Present (Elmt) loop
1785 Prim := Node (Elmt);
1787 -- Find an inherited hidden dispatching primitive with the name of S
1788 -- and a type-conformant profile.
1790 if Present (Alias (Prim))
1791 and then Is_Hidden (Alias (Prim))
1792 and then Find_Dispatching_Type (Alias (Prim)) /= Tag_Typ
1793 and then Primitive_Names_Match (S, Prim)
1794 and then Type_Conformant (S, Prim)
1797 Vis_Ancestor : Elmt_Id;
1801 -- The original corresponding operation of Prim must be an
1802 -- operation of a visible ancestor of the dispatching type S,
1803 -- and the original corresponding operation of S2 must be
1806 Orig_Prim := Original_Corresponding_Operation (Prim);
1808 if Orig_Prim /= Prim
1809 and then Is_Immediately_Visible (Orig_Prim)
1811 Vis_Ancestor := First_Elmt (Vis_List);
1812 while Present (Vis_Ancestor) loop
1814 First_Elmt (Primitive_Operations (Node (Vis_Ancestor)));
1815 while Present (Elmt) loop
1816 if Node (Elmt) = Orig_Prim then
1817 Set_Overridden_Operation (S, Prim);
1818 Set_Alias (Prim, Orig_Prim);
1825 Next_Elmt (Vis_Ancestor);
1835 end Find_Hidden_Overridden_Primitive;
1837 ---------------------------------------
1838 -- Find_Primitive_Covering_Interface --
1839 ---------------------------------------
1841 function Find_Primitive_Covering_Interface
1842 (Tagged_Type : Entity_Id;
1843 Iface_Prim : Entity_Id) return Entity_Id
1849 pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim))
1850 or else (Present (Alias (Iface_Prim))
1853 (Find_Dispatching_Type (Ultimate_Alias (Iface_Prim)))));
1855 -- Search in the homonym chain. Done to speed up locating visible
1856 -- entities and required to catch primitives associated with the partial
1857 -- view of private types when processing the corresponding full view.
1859 E := Current_Entity (Iface_Prim);
1860 while Present (E) loop
1861 if Is_Subprogram (E)
1862 and then Is_Dispatching_Operation (E)
1863 and then Is_Interface_Conformant (Tagged_Type, Iface_Prim, E)
1871 -- Search in the list of primitives of the type. Required to locate the
1872 -- covering primitive if the covering primitive is not visible (for
1873 -- example, non-visible inherited primitive of private type).
1875 El := First_Elmt (Primitive_Operations (Tagged_Type));
1876 while Present (El) loop
1879 -- Keep separate the management of internal entities that link
1880 -- primitives with interface primitives from tagged type primitives.
1882 if No (Interface_Alias (E)) then
1883 if Present (Alias (E)) then
1885 -- This interface primitive has not been covered yet
1887 if Alias (E) = Iface_Prim then
1890 -- The covering primitive was inherited
1892 elsif Overridden_Operation (Ultimate_Alias (E))
1899 -- Check if E covers the interface primitive (includes case in
1900 -- which E is an inherited private primitive).
1902 if Is_Interface_Conformant (Tagged_Type, Iface_Prim, E) then
1906 -- Use the internal entity that links the interface primitive with
1907 -- the covering primitive to locate the entity.
1909 elsif Interface_Alias (E) = Iface_Prim then
1919 end Find_Primitive_Covering_Interface;
1921 ---------------------------
1922 -- Inherited_Subprograms --
1923 ---------------------------
1925 function Inherited_Subprograms (S : Entity_Id) return Subprogram_List is
1926 Result : Subprogram_List (1 .. 6000);
1927 -- 6000 here is intended to be infinity. We could use an expandable
1928 -- table, but it would be awfully heavy, and there is no way that we
1929 -- could reasonably exceed this value.
1932 -- Number of entries in Result
1934 Parent_Op : Entity_Id;
1935 -- Traverses the Overridden_Operation chain
1937 procedure Store_IS (E : Entity_Id);
1938 -- Stores E in Result if not already stored
1944 procedure Store_IS (E : Entity_Id) is
1946 for J in 1 .. N loop
1947 if E = Result (J) then
1956 -- Start of processing for Inherited_Subprograms
1959 if Present (S) and then Is_Dispatching_Operation (S) then
1961 -- Deal with direct inheritance
1965 Parent_Op := Overridden_Operation (Parent_Op);
1966 exit when No (Parent_Op);
1968 if Is_Subprogram (Parent_Op)
1969 or else Is_Generic_Subprogram (Parent_Op)
1971 Store_IS (Parent_Op);
1975 -- Now deal with interfaces
1978 Tag_Typ : Entity_Id;
1983 Tag_Typ := Find_Dispatching_Type (S);
1985 if Is_Concurrent_Type (Tag_Typ) then
1986 Tag_Typ := Corresponding_Record_Type (Tag_Typ);
1989 -- Search primitive operations of dispatching type
1991 if Present (Tag_Typ)
1992 and then Present (Primitive_Operations (Tag_Typ))
1994 Elmt := First_Elmt (Primitive_Operations (Tag_Typ));
1995 while Present (Elmt) loop
1996 Prim := Node (Elmt);
1998 -- The following test eliminates some odd cases in which
1999 -- Ekind (Prim) is Void, to be investigated further ???
2001 if not (Is_Subprogram (Prim)
2003 Is_Generic_Subprogram (Prim))
2007 -- For [generic] subprogram, look at interface alias
2009 elsif Present (Interface_Alias (Prim))
2010 and then Alias (Prim) = S
2012 -- We have found a primitive covered by S
2014 Store_IS (Interface_Alias (Prim));
2023 return Result (1 .. N);
2024 end Inherited_Subprograms;
2026 ---------------------------
2027 -- Is_Dynamically_Tagged --
2028 ---------------------------
2030 function Is_Dynamically_Tagged (N : Node_Id) return Boolean is
2032 if Nkind (N) = N_Error then
2035 return Find_Controlling_Arg (N) /= Empty;
2037 end Is_Dynamically_Tagged;
2039 ---------------------------------
2040 -- Is_Null_Interface_Primitive --
2041 ---------------------------------
2043 function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean is
2045 return Comes_From_Source (E)
2046 and then Is_Dispatching_Operation (E)
2047 and then Ekind (E) = E_Procedure
2048 and then Null_Present (Parent (E))
2049 and then Is_Interface (Find_Dispatching_Type (E));
2050 end Is_Null_Interface_Primitive;
2052 --------------------------
2053 -- Is_Tag_Indeterminate --
2054 --------------------------
2056 function Is_Tag_Indeterminate (N : Node_Id) return Boolean is
2059 Orig_Node : constant Node_Id := Original_Node (N);
2062 if Nkind (Orig_Node) = N_Function_Call
2063 and then Is_Entity_Name (Name (Orig_Node))
2065 Nam := Entity (Name (Orig_Node));
2067 if not Has_Controlling_Result (Nam) then
2070 -- The function may have a controlling result, but if the return type
2071 -- is not visibly tagged, then this is not tag-indeterminate.
2073 elsif Is_Access_Type (Etype (Nam))
2074 and then not Is_Tagged_Type (Designated_Type (Etype (Nam)))
2078 -- An explicit dereference means that the call has already been
2079 -- expanded and there is no tag to propagate.
2081 elsif Nkind (N) = N_Explicit_Dereference then
2084 -- If there are no actuals, the call is tag-indeterminate
2086 elsif No (Parameter_Associations (Orig_Node)) then
2090 Actual := First_Actual (Orig_Node);
2091 while Present (Actual) loop
2092 if Is_Controlling_Actual (Actual)
2093 and then not Is_Tag_Indeterminate (Actual)
2095 -- One operand is dispatching
2100 Next_Actual (Actual);
2106 elsif Nkind (Orig_Node) = N_Qualified_Expression then
2107 return Is_Tag_Indeterminate (Expression (Orig_Node));
2109 -- Case of a call to the Input attribute (possibly rewritten), which is
2110 -- always tag-indeterminate except when its prefix is a Class attribute.
2112 elsif Nkind (Orig_Node) = N_Attribute_Reference
2114 Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input
2116 Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference
2120 -- In Ada 2005, a function that returns an anonymous access type can be
2121 -- dispatching, and the dereference of a call to such a function can
2122 -- also be tag-indeterminate if the call itself is.
2124 elsif Nkind (Orig_Node) = N_Explicit_Dereference
2125 and then Ada_Version >= Ada_2005
2127 return Is_Tag_Indeterminate (Prefix (Orig_Node));
2132 end Is_Tag_Indeterminate;
2134 ------------------------------------
2135 -- Override_Dispatching_Operation --
2136 ------------------------------------
2138 procedure Override_Dispatching_Operation
2139 (Tagged_Type : Entity_Id;
2140 Prev_Op : Entity_Id;
2147 -- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but
2148 -- we do it unconditionally in Ada 95 now, since this is our pragma!)
2150 if No_Return (Prev_Op) and then not No_Return (New_Op) then
2151 Error_Msg_N ("procedure & must have No_Return pragma", New_Op);
2152 Error_Msg_N ("\since overridden procedure has No_Return", New_Op);
2155 -- If there is no previous operation to override, the type declaration
2156 -- was malformed, and an error must have been emitted already.
2158 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
2159 while Present (Elmt)
2160 and then Node (Elmt) /= Prev_Op
2169 -- The location of entities that come from source in the list of
2170 -- primitives of the tagged type must follow their order of occurrence
2171 -- in the sources to fulfill the C++ ABI. If the overridden entity is a
2172 -- primitive of an interface that is not implemented by the parents of
2173 -- this tagged type (that is, it is an alias of an interface primitive
2174 -- generated by Derive_Interface_Progenitors), then we must append the
2175 -- new entity at the end of the list of primitives.
2177 if Present (Alias (Prev_Op))
2178 and then Etype (Tagged_Type) /= Tagged_Type
2179 and then Is_Interface (Find_Dispatching_Type (Alias (Prev_Op)))
2180 and then not Is_Ancestor (Find_Dispatching_Type (Alias (Prev_Op)),
2181 Tagged_Type, Use_Full_View => True)
2182 and then not Implements_Interface
2183 (Etype (Tagged_Type),
2184 Find_Dispatching_Type (Alias (Prev_Op)))
2186 Remove_Elmt (Primitive_Operations (Tagged_Type), Elmt);
2187 Append_Elmt (New_Op, Primitive_Operations (Tagged_Type));
2189 -- The new primitive replaces the overridden entity. Required to ensure
2190 -- that overriding primitive is assigned the same dispatch table slot.
2193 Replace_Elmt (Elmt, New_Op);
2196 if Ada_Version >= Ada_2005
2197 and then Has_Interfaces (Tagged_Type)
2199 -- Ada 2005 (AI-251): Update the attribute alias of all the aliased
2200 -- entities of the overridden primitive to reference New_Op, and also
2201 -- propagate the proper value of Is_Abstract_Subprogram. Verify
2202 -- that the new operation is subtype conformant with the interface
2203 -- operations that it implements (for operations inherited from the
2204 -- parent itself, this check is made when building the derived type).
2206 -- Note: This code is only executed in case of late overriding
2208 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
2209 while Present (Elmt) loop
2210 Prim := Node (Elmt);
2212 if Prim = New_Op then
2215 -- Note: The check on Is_Subprogram protects the frontend against
2216 -- reading attributes in entities that are not yet fully decorated
2218 elsif Is_Subprogram (Prim)
2219 and then Present (Interface_Alias (Prim))
2220 and then Alias (Prim) = Prev_Op
2221 and then Present (Etype (New_Op))
2223 Set_Alias (Prim, New_Op);
2224 Check_Subtype_Conformant (New_Op, Prim);
2225 Set_Is_Abstract_Subprogram (Prim,
2226 Is_Abstract_Subprogram (New_Op));
2228 -- Ensure that this entity will be expanded to fill the
2229 -- corresponding entry in its dispatch table.
2231 if not Is_Abstract_Subprogram (Prim) then
2232 Set_Has_Delayed_Freeze (Prim);
2240 if (not Is_Package_Or_Generic_Package (Current_Scope))
2241 or else not In_Private_Part (Current_Scope)
2243 -- Not a private primitive
2247 else pragma Assert (Is_Inherited_Operation (Prev_Op));
2249 -- Make the overriding operation into an alias of the implicit one.
2250 -- In this fashion a call from outside ends up calling the new body
2251 -- even if non-dispatching, and a call from inside calls the over-
2252 -- riding operation because it hides the implicit one. To indicate
2253 -- that the body of Prev_Op is never called, set its dispatch table
2254 -- entity to Empty. If the overridden operation has a dispatching
2255 -- result, so does the overriding one.
2257 Set_Alias (Prev_Op, New_Op);
2258 Set_DTC_Entity (Prev_Op, Empty);
2259 Set_Has_Controlling_Result (New_Op, Has_Controlling_Result (Prev_Op));
2262 end Override_Dispatching_Operation;
2268 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is
2269 Call_Node : Node_Id;
2273 if Nkind (Actual) = N_Function_Call then
2274 Call_Node := Actual;
2276 elsif Nkind (Actual) = N_Identifier
2277 and then Nkind (Original_Node (Actual)) = N_Function_Call
2279 -- Call rewritten as object declaration when stack-checking is
2280 -- enabled. Propagate tag to expression in declaration, which is
2283 Call_Node := Expression (Parent (Entity (Actual)));
2285 -- Ada 2005: If this is a dereference of a call to a function with a
2286 -- dispatching access-result, the tag is propagated when the dereference
2287 -- itself is expanded (see exp_ch6.adb) and there is nothing else to do.
2289 elsif Nkind (Actual) = N_Explicit_Dereference
2290 and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call
2294 -- When expansion is suppressed, an unexpanded call to 'Input can occur,
2295 -- and in that case we can simply return.
2297 elsif Nkind (Actual) = N_Attribute_Reference then
2298 pragma Assert (Attribute_Name (Actual) = Name_Input);
2302 -- Only other possibilities are parenthesized or qualified expression,
2303 -- or an expander-generated unchecked conversion of a function call to
2304 -- a stream Input attribute.
2307 Call_Node := Expression (Actual);
2310 -- Do not set the Controlling_Argument if already set. This happens in
2311 -- the special case of _Input (see Exp_Attr, case Input).
2313 if No (Controlling_Argument (Call_Node)) then
2314 Set_Controlling_Argument (Call_Node, Control);
2317 Arg := First_Actual (Call_Node);
2318 while Present (Arg) loop
2319 if Is_Tag_Indeterminate (Arg) then
2320 Propagate_Tag (Control, Arg);
2326 -- Expansion of dispatching calls is suppressed when VM_Target, because
2327 -- the VM back-ends directly handle the generation of dispatching calls
2328 -- and would have to undo any expansion to an indirect call.
2330 if Tagged_Type_Expansion then
2332 Call_Typ : constant Entity_Id := Etype (Call_Node);
2335 Expand_Dispatching_Call (Call_Node);
2337 -- If the controlling argument is an interface type and the type
2338 -- of Call_Node differs then we must add an implicit conversion to
2339 -- force displacement of the pointer to the object to reference
2340 -- the secondary dispatch table of the interface.
2342 if Is_Interface (Etype (Control))
2343 and then Etype (Control) /= Call_Typ
2345 -- Cannot use Convert_To because the previous call to
2346 -- Expand_Dispatching_Call leaves decorated the Call_Node
2347 -- with the type of Control.
2350 Make_Type_Conversion (Sloc (Call_Node),
2352 New_Occurrence_Of (Etype (Control), Sloc (Call_Node)),
2353 Expression => Relocate_Node (Call_Node)));
2354 Set_Etype (Call_Node, Etype (Control));
2355 Set_Analyzed (Call_Node);
2357 Expand_Interface_Conversion (Call_Node, Is_Static => False);
2361 -- Expansion of a dispatching call results in an indirect call, which in
2362 -- turn causes current values to be killed (see Resolve_Call), so on VM
2363 -- targets we do the call here to ensure consistent warnings between VM
2364 -- and non-VM targets.
2367 Kill_Current_Values;