1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2009, 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 Tbuild; use Tbuild;
53 with Uintp; use Uintp;
55 package body Sem_Disp is
57 -----------------------
58 -- Local Subprograms --
59 -----------------------
61 procedure Add_Dispatching_Operation
62 (Tagged_Type : Entity_Id;
64 -- Add New_Op in the list of primitive operations of Tagged_Type
66 function Check_Controlling_Type
68 Subp : Entity_Id) return Entity_Id;
69 -- T is the tagged type of a formal parameter or the result of Subp.
70 -- If the subprogram has a controlling parameter or result that matches
71 -- the type, then returns the tagged type of that parameter or result
72 -- (returning the designated tagged type in the case of an access
73 -- parameter); otherwise returns empty.
75 -------------------------------
76 -- Add_Dispatching_Operation --
77 -------------------------------
79 procedure Add_Dispatching_Operation
80 (Tagged_Type : Entity_Id;
83 List : constant Elist_Id := Primitive_Operations (Tagged_Type);
86 -- The dispatching operation may already be on the list, if it is the
87 -- wrapper for an inherited function of a null extension (see Exp_Ch3
88 -- for the construction of function wrappers). The list of primitive
89 -- operations must not contain duplicates.
91 Append_Unique_Elmt (New_Op, List);
92 end Add_Dispatching_Operation;
94 -------------------------------
95 -- Check_Controlling_Formals --
96 -------------------------------
98 procedure Check_Controlling_Formals
103 Ctrl_Type : Entity_Id;
106 Formal := First_Formal (Subp);
107 while Present (Formal) loop
108 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
110 if Present (Ctrl_Type) then
112 -- When controlling type is concurrent and declared within a
113 -- generic or inside an instance use corresponding record type.
115 if Is_Concurrent_Type (Ctrl_Type)
116 and then Present (Corresponding_Record_Type (Ctrl_Type))
118 Ctrl_Type := Corresponding_Record_Type (Ctrl_Type);
121 if Ctrl_Type = Typ then
122 Set_Is_Controlling_Formal (Formal);
124 -- Ada 2005 (AI-231): Anonymous access types that are used in
125 -- controlling parameters exclude null because it is necessary
126 -- to read the tag to dispatch, and null has no tag.
128 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
129 Set_Can_Never_Be_Null (Etype (Formal));
130 Set_Is_Known_Non_Null (Etype (Formal));
133 -- Check that the parameter's nominal subtype statically
134 -- matches the first subtype.
136 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
137 if not Subtypes_Statically_Match
138 (Typ, Designated_Type (Etype (Formal)))
141 ("parameter subtype does not match controlling type",
145 elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then
147 ("parameter subtype does not match controlling type",
151 if Present (Default_Value (Formal)) then
153 -- In Ada 2005, access parameters can have defaults
155 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
156 and then Ada_Version < Ada_05
159 ("default not allowed for controlling access parameter",
160 Default_Value (Formal));
162 elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then
164 ("default expression must be a tag indeterminate" &
165 " function call", Default_Value (Formal));
169 elsif Comes_From_Source (Subp) then
171 ("operation can be dispatching in only one type", Subp);
175 Next_Formal (Formal);
178 if Ekind (Subp) = E_Function
180 Ekind (Subp) = E_Generic_Function
182 Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp);
184 if Present (Ctrl_Type) then
185 if Ctrl_Type = Typ then
186 Set_Has_Controlling_Result (Subp);
188 -- Check that result subtype statically matches first subtype
189 -- (Ada 2005): Subp may have a controlling access result.
191 if Subtypes_Statically_Match (Typ, Etype (Subp))
192 or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type
194 Subtypes_Statically_Match
195 (Typ, Designated_Type (Etype (Subp))))
201 ("result subtype does not match controlling type", Subp);
204 elsif Comes_From_Source (Subp) then
206 ("operation can be dispatching in only one type", Subp);
210 end Check_Controlling_Formals;
212 ----------------------------
213 -- Check_Controlling_Type --
214 ----------------------------
216 function Check_Controlling_Type
218 Subp : Entity_Id) return Entity_Id
220 Tagged_Type : Entity_Id := Empty;
223 if Is_Tagged_Type (T) then
224 if Is_First_Subtype (T) then
227 Tagged_Type := Base_Type (T);
230 elsif Ekind (T) = E_Anonymous_Access_Type
231 and then Is_Tagged_Type (Designated_Type (T))
233 if Ekind (Designated_Type (T)) /= E_Incomplete_Type then
234 if Is_First_Subtype (Designated_Type (T)) then
235 Tagged_Type := Designated_Type (T);
237 Tagged_Type := Base_Type (Designated_Type (T));
240 -- Ada 2005: an incomplete type can be tagged. An operation with an
241 -- access parameter of the type is dispatching.
243 elsif Scope (Designated_Type (T)) = Current_Scope then
244 Tagged_Type := Designated_Type (T);
246 -- Ada 2005 (AI-50217)
248 elsif From_With_Type (Designated_Type (T))
249 and then Present (Non_Limited_View (Designated_Type (T)))
251 if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then
252 Tagged_Type := Non_Limited_View (Designated_Type (T));
254 Tagged_Type := Base_Type (Non_Limited_View
255 (Designated_Type (T)));
260 if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then
263 -- The dispatching type and the primitive operation must be defined in
264 -- the same scope, except in the case of internal operations and formal
265 -- abstract subprograms.
267 elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp))
268 and then (not Is_Generic_Type (Tagged_Type)
269 or else not Comes_From_Source (Subp)))
271 (Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp))
273 (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration
275 Present (Corresponding_Formal_Spec (Parent (Parent (Subp))))
277 Is_Abstract_Subprogram (Subp))
284 end Check_Controlling_Type;
286 ----------------------------
287 -- Check_Dispatching_Call --
288 ----------------------------
290 procedure Check_Dispatching_Call (N : Node_Id) is
291 Loc : constant Source_Ptr := Sloc (N);
294 Control : Node_Id := Empty;
296 Subp_Entity : Entity_Id;
297 Indeterm_Ancestor_Call : Boolean := False;
298 Indeterm_Ctrl_Type : Entity_Id;
300 Static_Tag : Node_Id := Empty;
301 -- If a controlling formal has a statically tagged actual, the tag of
302 -- this actual is to be used for any tag-indeterminate actual.
304 procedure Check_Direct_Call;
305 -- In the case when the controlling actual is a class-wide type whose
306 -- root type's completion is a task or protected type, the call is in
307 -- fact direct. This routine detects the above case and modifies the
310 procedure Check_Dispatching_Context;
311 -- If the call is tag-indeterminate and the entity being called is
312 -- abstract, verify that the context is a call that will eventually
313 -- provide a tag for dispatching, or has provided one already.
315 -----------------------
316 -- Check_Direct_Call --
317 -----------------------
319 procedure Check_Direct_Call is
320 Typ : Entity_Id := Etype (Control);
322 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean;
323 -- Determine whether an entity denotes a user-defined equality
325 ------------------------------
326 -- Is_User_Defined_Equality --
327 ------------------------------
329 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is
332 Ekind (Id) = E_Function
333 and then Chars (Id) = Name_Op_Eq
334 and then Comes_From_Source (Id)
336 -- Internally generated equalities have a full type declaration
339 and then Nkind (Parent (Id)) = N_Function_Specification;
340 end Is_User_Defined_Equality;
342 -- Start of processing for Check_Direct_Call
345 -- Predefined primitives do not receive wrappers since they are built
346 -- from scratch for the corresponding record of synchronized types.
347 -- Equality is in general predefined, but is excluded from the check
348 -- when it is user-defined.
350 if Is_Predefined_Dispatching_Operation (Subp_Entity)
351 and then not Is_User_Defined_Equality (Subp_Entity)
356 if Is_Class_Wide_Type (Typ) then
357 Typ := Root_Type (Typ);
360 if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
361 Typ := Full_View (Typ);
364 if Is_Concurrent_Type (Typ)
366 Present (Corresponding_Record_Type (Typ))
368 Typ := Corresponding_Record_Type (Typ);
370 -- The concurrent record's list of primitives should contain a
371 -- wrapper for the entity of the call, retrieve it.
376 Wrapper_Found : Boolean := False;
379 Prim_Elmt := First_Elmt (Primitive_Operations (Typ));
380 while Present (Prim_Elmt) loop
381 Prim := Node (Prim_Elmt);
383 if Is_Primitive_Wrapper (Prim)
384 and then Wrapped_Entity (Prim) = Subp_Entity
386 Wrapper_Found := True;
390 Next_Elmt (Prim_Elmt);
393 -- A primitive declared between two views should have a
394 -- corresponding wrapper.
396 pragma Assert (Wrapper_Found);
398 -- Modify the call by setting the proper entity
400 Set_Entity (Name (N), Prim);
403 end Check_Direct_Call;
405 -------------------------------
406 -- Check_Dispatching_Context --
407 -------------------------------
409 procedure Check_Dispatching_Context is
410 Subp : constant Entity_Id := Entity (Name (N));
414 if Is_Abstract_Subprogram (Subp)
415 and then No (Controlling_Argument (N))
417 if Present (Alias (Subp))
418 and then not Is_Abstract_Subprogram (Alias (Subp))
419 and then No (DTC_Entity (Subp))
421 -- Private overriding of inherited abstract operation, call is
424 Set_Entity (Name (N), Alias (Subp));
429 while Present (Par) loop
430 if Nkind_In (Par, N_Function_Call,
431 N_Procedure_Call_Statement,
432 N_Assignment_Statement,
435 and then Is_Tagged_Type (Etype (Subp))
439 elsif Nkind (Par) = N_Qualified_Expression
440 or else Nkind (Par) = N_Unchecked_Type_Conversion
445 if Ekind (Subp) = E_Function then
447 ("call to abstract function must be dispatching", N);
449 -- This error can occur for a procedure in the case of a
450 -- call to an abstract formal procedure with a statically
455 ("call to abstract procedure must be dispatching",
464 end Check_Dispatching_Context;
466 -- Start of processing for Check_Dispatching_Call
469 -- Find a controlling argument, if any
471 if Present (Parameter_Associations (N)) then
472 Subp_Entity := Entity (Name (N));
474 Actual := First_Actual (N);
475 Formal := First_Formal (Subp_Entity);
476 while Present (Actual) loop
477 Control := Find_Controlling_Arg (Actual);
478 exit when Present (Control);
480 -- Check for the case where the actual is a tag-indeterminate call
481 -- whose result type is different than the tagged type associated
482 -- with the containing call, but is an ancestor of the type.
484 if Is_Controlling_Formal (Formal)
485 and then Is_Tag_Indeterminate (Actual)
486 and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal))
487 and then Is_Ancestor (Etype (Actual), Etype (Formal))
489 Indeterm_Ancestor_Call := True;
490 Indeterm_Ctrl_Type := Etype (Formal);
492 -- If the formal is controlling but the actual is not, the type
493 -- of the actual is statically known, and may be used as the
494 -- controlling tag for some other tag-indeterminate actual.
496 elsif Is_Controlling_Formal (Formal)
497 and then Is_Entity_Name (Actual)
498 and then Is_Tagged_Type (Etype (Actual))
500 Static_Tag := Actual;
503 Next_Actual (Actual);
504 Next_Formal (Formal);
507 -- If the call doesn't have a controlling actual but does have an
508 -- indeterminate actual that requires dispatching treatment, then an
509 -- object is needed that will serve as the controlling argument for a
510 -- dispatching call on the indeterminate actual. This can only occur
511 -- in the unusual situation of a default actual given by a
512 -- tag-indeterminate call and where the type of the call is an
513 -- ancestor of the type associated with a containing call to an
514 -- inherited operation (see AI-239).
516 -- Rather than create an object of the tagged type, which would be
517 -- problematic for various reasons (default initialization,
518 -- discriminants), the tag of the containing call's associated tagged
519 -- type is directly used to control the dispatching.
522 and then Indeterm_Ancestor_Call
523 and then No (Static_Tag)
526 Make_Attribute_Reference (Loc,
527 Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc),
528 Attribute_Name => Name_Tag);
533 if Present (Control) then
535 -- Verify that no controlling arguments are statically tagged
538 Write_Str ("Found Dispatching call");
543 Actual := First_Actual (N);
544 while Present (Actual) loop
545 if Actual /= Control then
547 if not Is_Controlling_Actual (Actual) then
548 null; -- Can be anything
550 elsif Is_Dynamically_Tagged (Actual) then
551 null; -- Valid parameter
553 elsif Is_Tag_Indeterminate (Actual) then
555 -- The tag is inherited from the enclosing call (the node
556 -- we are currently analyzing). Explicitly expand the
557 -- actual, since the previous call to Expand (from
558 -- Resolve_Call) had no way of knowing about the required
561 Propagate_Tag (Control, Actual);
565 ("controlling argument is not dynamically tagged",
571 Next_Actual (Actual);
574 -- Mark call as a dispatching call
576 Set_Controlling_Argument (N, Control);
577 Check_Restriction (No_Dispatching_Calls, N);
579 -- The dispatching call may need to be converted into a direct
580 -- call in certain cases.
584 -- If there is a statically tagged actual and a tag-indeterminate
585 -- call to a function of the ancestor (such as that provided by a
586 -- default), then treat this as a dispatching call and propagate
587 -- the tag to the tag-indeterminate call(s).
589 elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then
591 Make_Attribute_Reference (Loc,
593 New_Occurrence_Of (Etype (Static_Tag), Loc),
594 Attribute_Name => Name_Tag);
598 Actual := First_Actual (N);
599 Formal := First_Formal (Subp_Entity);
600 while Present (Actual) loop
601 if Is_Tag_Indeterminate (Actual)
602 and then Is_Controlling_Formal (Formal)
604 Propagate_Tag (Control, Actual);
607 Next_Actual (Actual);
608 Next_Formal (Formal);
611 Check_Dispatching_Context;
614 -- The call is not dispatching, so check that there aren't any
615 -- tag-indeterminate abstract calls left.
617 Actual := First_Actual (N);
618 while Present (Actual) loop
619 if Is_Tag_Indeterminate (Actual) then
621 -- Function call case
623 if Nkind (Original_Node (Actual)) = N_Function_Call then
624 Func := Entity (Name (Original_Node (Actual)));
626 -- If the actual is an attribute then it can't be abstract
627 -- (the only current case of a tag-indeterminate attribute
628 -- is the stream Input attribute).
631 Nkind (Original_Node (Actual)) = N_Attribute_Reference
635 -- Only other possibility is a qualified expression whose
636 -- constituent expression is itself a call.
642 (Expression (Original_Node (Actual)))));
645 if Present (Func) and then Is_Abstract_Subprogram (Func) then
647 "call to abstract function must be dispatching", N);
651 Next_Actual (Actual);
654 Check_Dispatching_Context;
658 -- If dispatching on result, the enclosing call, if any, will
659 -- determine the controlling argument. Otherwise this is the
660 -- primitive operation of the root type.
662 Check_Dispatching_Context;
664 end Check_Dispatching_Call;
666 ---------------------------------
667 -- Check_Dispatching_Operation --
668 ---------------------------------
670 procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id) is
671 Tagged_Type : Entity_Id;
672 Has_Dispatching_Parent : Boolean := False;
673 Body_Is_Last_Primitive : Boolean := False;
676 if Ekind (Subp) /= E_Procedure and then Ekind (Subp) /= E_Function then
680 Set_Is_Dispatching_Operation (Subp, False);
681 Tagged_Type := Find_Dispatching_Type (Subp);
685 if Ada_Version = Ada_05
686 and then Present (Tagged_Type)
687 and then Is_Concurrent_Type (Tagged_Type)
689 -- Protect the frontend against previously detected errors
691 if No (Corresponding_Record_Type (Tagged_Type)) then
695 Tagged_Type := Corresponding_Record_Type (Tagged_Type);
698 -- (AI-345): The task body procedure is not a primitive of the tagged
701 if Present (Tagged_Type)
702 and then Is_Concurrent_Record_Type (Tagged_Type)
703 and then Present (Corresponding_Concurrent_Type (Tagged_Type))
704 and then Is_Task_Type (Corresponding_Concurrent_Type (Tagged_Type))
705 and then Subp = Get_Task_Body_Procedure
706 (Corresponding_Concurrent_Type (Tagged_Type))
711 -- If Subp is derived from a dispatching operation then it should
712 -- always be treated as dispatching. In this case various checks
713 -- below will be bypassed. Makes sure that late declarations for
714 -- inherited private subprograms are treated as dispatching, even
715 -- if the associated tagged type is already frozen.
717 Has_Dispatching_Parent :=
718 Present (Alias (Subp))
719 and then Is_Dispatching_Operation (Alias (Subp));
721 if No (Tagged_Type) then
723 -- Ada 2005 (AI-251): Check that Subp is not a primitive associated
724 -- with an abstract interface type unless the interface acts as a
725 -- parent type in a derivation. If the interface type is a formal
726 -- type then the operation is not primitive and therefore legal.
733 E := First_Entity (Subp);
734 while Present (E) loop
736 -- For an access parameter, check designated type
738 if Ekind (Etype (E)) = E_Anonymous_Access_Type then
739 Typ := Designated_Type (Etype (E));
744 if Comes_From_Source (Subp)
745 and then Is_Interface (Typ)
746 and then not Is_Class_Wide_Type (Typ)
747 and then not Is_Derived_Type (Typ)
748 and then not Is_Generic_Type (Typ)
749 and then not In_Instance
751 Error_Msg_N ("?declaration of& is too late!", Subp);
753 ("\spec should appear immediately after declaration of &!",
761 -- In case of functions check also the result type
763 if Ekind (Subp) = E_Function then
764 if Is_Access_Type (Etype (Subp)) then
765 Typ := Designated_Type (Etype (Subp));
770 if not Is_Class_Wide_Type (Typ)
771 and then Is_Interface (Typ)
772 and then not Is_Derived_Type (Typ)
774 Error_Msg_N ("?declaration of& is too late!", Subp);
776 ("\spec should appear immediately after declaration of &!",
784 -- The subprograms build internally after the freezing point (such as
785 -- init procs, interface thunks, type support subprograms, and Offset
786 -- to top functions for accessing interface components in variable
787 -- size tagged types) are not primitives.
789 elsif Is_Frozen (Tagged_Type)
790 and then not Comes_From_Source (Subp)
791 and then not Has_Dispatching_Parent
793 -- Complete decoration if internally built subprograms that override
794 -- a dispatching primitive. These entities correspond with the
797 -- 1. Ada 2005 (AI-391): Wrapper functions built by the expander
798 -- to override functions of nonabstract null extensions. These
799 -- primitives were added to the list of primitives of the tagged
800 -- type by Make_Controlling_Function_Wrappers. However, attribute
801 -- Is_Dispatching_Operation must be set to true.
803 -- 2. Subprograms associated with stream attributes (built by
804 -- New_Stream_Subprogram)
806 if Present (Old_Subp)
807 and then Is_Overriding_Operation (Subp)
808 and then Is_Dispatching_Operation (Old_Subp)
811 ((Ekind (Subp) = E_Function
812 and then Is_Dispatching_Operation (Old_Subp)
813 and then Is_Null_Extension (Base_Type (Etype (Subp))))
814 or else Get_TSS_Name (Subp) = TSS_Stream_Read
815 or else Get_TSS_Name (Subp) = TSS_Stream_Write);
817 Set_Is_Dispatching_Operation (Subp);
822 -- The operation may be a child unit, whose scope is the defining
823 -- package, but which is not a primitive operation of the type.
825 elsif Is_Child_Unit (Subp) then
828 -- If the subprogram is not defined in a package spec, the only case
829 -- where it can be a dispatching op is when it overrides an operation
830 -- before the freezing point of the type.
832 elsif ((not Is_Package_Or_Generic_Package (Scope (Subp)))
833 or else In_Package_Body (Scope (Subp)))
834 and then not Has_Dispatching_Parent
836 if not Comes_From_Source (Subp)
837 or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type))
841 -- If the type is already frozen, the overriding is not allowed
842 -- except when Old_Subp is not a dispatching operation (which can
843 -- occur when Old_Subp was inherited by an untagged type). However,
844 -- a body with no previous spec freezes the type *after* its
845 -- declaration, and therefore is a legal overriding (unless the type
846 -- has already been frozen). Only the first such body is legal.
848 elsif Present (Old_Subp)
849 and then Is_Dispatching_Operation (Old_Subp)
851 if Comes_From_Source (Subp)
853 (Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body
854 or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub)
857 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
861 -- ??? The checks here for whether the type has been
862 -- frozen prior to the new body are not complete. It's
863 -- not simple to check frozenness at this point since
864 -- the body has already caused the type to be prematurely
865 -- frozen in Analyze_Declarations, but we're forced to
866 -- recheck this here because of the odd rule interpretation
867 -- that allows the overriding if the type wasn't frozen
868 -- prior to the body. The freezing action should probably
869 -- be delayed until after the spec is seen, but that's
870 -- a tricky change to the delicate freezing code.
872 -- Look at each declaration following the type up until the
873 -- new subprogram body. If any of the declarations is a body
874 -- then the type has been frozen already so the overriding
875 -- primitive is illegal.
877 Decl_Item := Next (Parent (Tagged_Type));
878 while Present (Decl_Item)
879 and then (Decl_Item /= Subp_Body)
881 if Comes_From_Source (Decl_Item)
882 and then (Nkind (Decl_Item) in N_Proper_Body
883 or else Nkind (Decl_Item) in N_Body_Stub)
885 Error_Msg_N ("overriding of& is too late!", Subp);
887 ("\spec should appear immediately after the type!",
895 -- If the subprogram doesn't follow in the list of
896 -- declarations including the type then the type has
897 -- definitely been frozen already and the body is illegal.
899 if No (Decl_Item) then
900 Error_Msg_N ("overriding of& is too late!", Subp);
902 ("\spec should appear immediately after the type!",
905 elsif Is_Frozen (Subp) then
907 -- The subprogram body declares a primitive operation.
908 -- if the subprogram is already frozen, we must update
909 -- its dispatching information explicitly here. The
910 -- information is taken from the overridden subprogram.
911 -- We must also generate a cross-reference entry because
912 -- references to other primitives were already created
913 -- when type was frozen.
915 Body_Is_Last_Primitive := True;
917 if Present (DTC_Entity (Old_Subp)) then
918 Set_DTC_Entity (Subp, DTC_Entity (Old_Subp));
919 Set_DT_Position (Subp, DT_Position (Old_Subp));
921 if not Restriction_Active (No_Dispatching_Calls) then
922 if Building_Static_DT (Tagged_Type) then
924 -- If the static dispatch table has not been
925 -- built then there is nothing else to do now;
926 -- otherwise we notify that we cannot build the
927 -- static dispatch table.
929 if Has_Dispatch_Table (Tagged_Type) then
931 ("overriding of& is too late for building" &
932 " static dispatch tables!", Subp);
934 ("\spec should appear immediately after" &
939 Insert_Actions_After (Subp_Body,
940 Register_Primitive (Sloc (Subp_Body),
944 -- Indicate that this is an overriding operation,
945 -- and replace the overriden entry in the list of
946 -- primitive operations, which is used for xref
947 -- generation subsequently.
949 Generate_Reference (Tagged_Type, Subp, 'P', False);
950 Override_Dispatching_Operation
951 (Tagged_Type, Old_Subp, Subp);
958 Error_Msg_N ("overriding of& is too late!", Subp);
960 ("\subprogram spec should appear immediately after the type!",
964 -- If the type is not frozen yet and we are not in the overriding
965 -- case it looks suspiciously like an attempt to define a primitive
966 -- operation, which requires the declaration to be in a package spec
969 elsif not Is_Frozen (Tagged_Type) then
971 ("?not dispatching (must be defined in a package spec)", Subp);
974 -- When the type is frozen, it is legitimate to define a new
975 -- non-primitive operation.
981 -- Now, we are sure that the scope is a package spec. If the subprogram
982 -- is declared after the freezing point of the type that's an error
984 elsif Is_Frozen (Tagged_Type) and then not Has_Dispatching_Parent then
985 Error_Msg_N ("this primitive operation is declared too late", Subp);
987 ("?no primitive operations for& after this line",
988 Freeze_Node (Tagged_Type),
993 Check_Controlling_Formals (Tagged_Type, Subp);
995 -- Now it should be a correct primitive operation, put it in the list
997 if Present (Old_Subp) then
999 -- If the type has interfaces we complete this check after we set
1000 -- attribute Is_Dispatching_Operation.
1002 Check_Subtype_Conformant (Subp, Old_Subp);
1004 if (Chars (Subp) = Name_Initialize
1005 or else Chars (Subp) = Name_Adjust
1006 or else Chars (Subp) = Name_Finalize)
1007 and then Is_Controlled (Tagged_Type)
1008 and then not Is_Visibly_Controlled (Tagged_Type)
1010 Set_Is_Overriding_Operation (Subp, False);
1012 -- If the subprogram specification carries an overriding
1013 -- indicator, no need for the warning: it is either redundant,
1014 -- or else an error will be reported.
1016 if Nkind (Parent (Subp)) = N_Procedure_Specification
1018 (Must_Override (Parent (Subp))
1019 or else Must_Not_Override (Parent (Subp)))
1023 -- Here we need the warning
1027 ("operation does not override inherited&?", Subp, Subp);
1031 Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp);
1032 Set_Is_Overriding_Operation (Subp);
1034 -- Ada 2005 (AI-251): In case of late overriding of a primitive
1035 -- that covers abstract interface subprograms we must register it
1036 -- in all the secondary dispatch tables associated with abstract
1037 -- interfaces. We do this now only if not building static tables.
1038 -- Otherwise the patch code is emitted after those tables are
1039 -- built, to prevent access_before_elaboration in gigi.
1041 if Body_Is_Last_Primitive then
1043 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
1048 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1049 while Present (Elmt) loop
1050 Prim := Node (Elmt);
1052 if Present (Alias (Prim))
1053 and then Present (Interface_Alias (Prim))
1054 and then Alias (Prim) = Subp
1055 and then not Building_Static_DT (Tagged_Type)
1057 Insert_Actions_After (Subp_Body,
1058 Register_Primitive (Sloc (Subp_Body), Prim => Prim));
1064 -- Redisplay the contents of the updated dispatch table
1066 if Debug_Flag_ZZ then
1067 Write_Str ("Late overriding: ");
1068 Write_DT (Tagged_Type);
1074 -- If no old subprogram, then we add this as a dispatching operation,
1075 -- but we avoid doing this if an error was posted, to prevent annoying
1078 elsif not Error_Posted (Subp) then
1079 Add_Dispatching_Operation (Tagged_Type, Subp);
1082 Set_Is_Dispatching_Operation (Subp, True);
1084 -- Ada 2005 (AI-251): If the type implements interfaces we must check
1085 -- subtype conformance against all the interfaces covered by this
1088 if Present (Old_Subp)
1089 and then Has_Interfaces (Tagged_Type)
1092 Ifaces_List : Elist_Id;
1093 Iface_Elmt : Elmt_Id;
1094 Iface_Prim_Elmt : Elmt_Id;
1095 Iface_Prim : Entity_Id;
1096 Ret_Typ : Entity_Id;
1099 Collect_Interfaces (Tagged_Type, Ifaces_List);
1101 Iface_Elmt := First_Elmt (Ifaces_List);
1102 while Present (Iface_Elmt) loop
1103 if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then
1105 First_Elmt (Primitive_Operations (Node (Iface_Elmt)));
1106 while Present (Iface_Prim_Elmt) loop
1107 Iface_Prim := Node (Iface_Prim_Elmt);
1109 if Is_Interface_Conformant
1110 (Tagged_Type, Iface_Prim, Subp)
1112 -- Handle procedures, functions whose return type
1113 -- matches, or functions not returning interfaces
1115 if Ekind (Subp) = E_Procedure
1116 or else Etype (Iface_Prim) = Etype (Subp)
1117 or else not Is_Interface (Etype (Iface_Prim))
1119 Check_Subtype_Conformant
1121 Old_Id => Iface_Prim,
1123 Skip_Controlling_Formals => True);
1125 -- Handle functions returning interfaces
1127 elsif Implements_Interface
1128 (Etype (Subp), Etype (Iface_Prim))
1130 -- Temporarily force both entities to return the
1131 -- same type. Required because Subtype_Conformant
1132 -- does not handle this case.
1134 Ret_Typ := Etype (Iface_Prim);
1135 Set_Etype (Iface_Prim, Etype (Subp));
1137 Check_Subtype_Conformant
1139 Old_Id => Iface_Prim,
1141 Skip_Controlling_Formals => True);
1143 Set_Etype (Iface_Prim, Ret_Typ);
1147 Next_Elmt (Iface_Prim_Elmt);
1151 Next_Elmt (Iface_Elmt);
1156 if not Body_Is_Last_Primitive then
1157 Set_DT_Position (Subp, No_Uint);
1159 elsif Has_Controlled_Component (Tagged_Type)
1161 (Chars (Subp) = Name_Initialize
1163 Chars (Subp) = Name_Adjust
1165 Chars (Subp) = Name_Finalize)
1168 F_Node : constant Node_Id := Freeze_Node (Tagged_Type);
1172 Old_Spec : Entity_Id;
1174 C_Names : constant array (1 .. 3) of Name_Id :=
1179 D_Names : constant array (1 .. 3) of TSS_Name_Type :=
1180 (TSS_Deep_Initialize,
1185 -- Remove previous controlled function which was constructed and
1186 -- analyzed when the type was frozen. This requires removing the
1187 -- body of the redefined primitive, as well as its specification
1188 -- if needed (there is no spec created for Deep_Initialize, see
1189 -- exp_ch3.adb). We must also dismantle the exception information
1190 -- that may have been generated for it when front end zero-cost
1191 -- tables are enabled.
1193 for J in D_Names'Range loop
1194 Old_P := TSS (Tagged_Type, D_Names (J));
1197 and then Chars (Subp) = C_Names (J)
1199 Old_Bod := Unit_Declaration_Node (Old_P);
1201 Set_Is_Eliminated (Old_P);
1202 Set_Scope (Old_P, Scope (Current_Scope));
1204 if Nkind (Old_Bod) = N_Subprogram_Body
1205 and then Present (Corresponding_Spec (Old_Bod))
1207 Old_Spec := Corresponding_Spec (Old_Bod);
1208 Set_Has_Completion (Old_Spec, False);
1213 Build_Late_Proc (Tagged_Type, Chars (Subp));
1215 -- The new operation is added to the actions of the freeze node
1216 -- for the type, but this node has already been analyzed, so we
1217 -- must retrieve and analyze explicitly the new body.
1220 and then Present (Actions (F_Node))
1222 Decl := Last (Actions (F_Node));
1227 end Check_Dispatching_Operation;
1229 ------------------------------------------
1230 -- Check_Operation_From_Incomplete_Type --
1231 ------------------------------------------
1233 procedure Check_Operation_From_Incomplete_Type
1237 Full : constant Entity_Id := Full_View (Typ);
1238 Parent_Typ : constant Entity_Id := Etype (Full);
1239 Old_Prim : constant Elist_Id := Primitive_Operations (Parent_Typ);
1240 New_Prim : constant Elist_Id := Primitive_Operations (Full);
1242 Prev : Elmt_Id := No_Elmt;
1244 function Derives_From (Proc : Entity_Id) return Boolean;
1245 -- Check that Subp has the signature of an operation derived from Proc.
1246 -- Subp has an access parameter that designates Typ.
1252 function Derives_From (Proc : Entity_Id) return Boolean is
1256 if Chars (Proc) /= Chars (Subp) then
1260 F1 := First_Formal (Proc);
1261 F2 := First_Formal (Subp);
1262 while Present (F1) and then Present (F2) loop
1263 if Ekind (Etype (F1)) = E_Anonymous_Access_Type then
1264 if Ekind (Etype (F2)) /= E_Anonymous_Access_Type then
1266 elsif Designated_Type (Etype (F1)) = Parent_Typ
1267 and then Designated_Type (Etype (F2)) /= Full
1272 elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then
1275 elsif Etype (F1) /= Etype (F2) then
1283 return No (F1) and then No (F2);
1286 -- Start of processing for Check_Operation_From_Incomplete_Type
1289 -- The operation may override an inherited one, or may be a new one
1290 -- altogether. The inherited operation will have been hidden by the
1291 -- current one at the point of the type derivation, so it does not
1292 -- appear in the list of primitive operations of the type. We have to
1293 -- find the proper place of insertion in the list of primitive opera-
1294 -- tions by iterating over the list for the parent type.
1296 Op1 := First_Elmt (Old_Prim);
1297 Op2 := First_Elmt (New_Prim);
1298 while Present (Op1) and then Present (Op2) loop
1299 if Derives_From (Node (Op1)) then
1302 -- Avoid adding it to the list of primitives if already there!
1304 if Node (Op2) /= Subp then
1305 Prepend_Elmt (Subp, New_Prim);
1309 Insert_Elmt_After (Subp, Prev);
1320 -- Operation is a new primitive
1322 Append_Elmt (Subp, New_Prim);
1323 end Check_Operation_From_Incomplete_Type;
1325 ---------------------------------------
1326 -- Check_Operation_From_Private_View --
1327 ---------------------------------------
1329 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is
1330 Tagged_Type : Entity_Id;
1333 if Is_Dispatching_Operation (Alias (Subp)) then
1334 Set_Scope (Subp, Current_Scope);
1335 Tagged_Type := Find_Dispatching_Type (Subp);
1337 -- Add Old_Subp to primitive operations if not already present
1339 if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then
1340 Append_Unique_Elmt (Old_Subp, Primitive_Operations (Tagged_Type));
1342 -- If Old_Subp isn't already marked as dispatching then
1343 -- this is the case of an operation of an untagged private
1344 -- type fulfilled by a tagged type that overrides an
1345 -- inherited dispatching operation, so we set the necessary
1346 -- dispatching attributes here.
1348 if not Is_Dispatching_Operation (Old_Subp) then
1350 -- If the untagged type has no discriminants, and the full
1351 -- view is constrained, there will be a spurious mismatch
1352 -- of subtypes on the controlling arguments, because the tagged
1353 -- type is the internal base type introduced in the derivation.
1354 -- Use the original type to verify conformance, rather than the
1357 if not Comes_From_Source (Tagged_Type)
1358 and then Has_Discriminants (Tagged_Type)
1364 Formal := First_Formal (Old_Subp);
1365 while Present (Formal) loop
1366 if Tagged_Type = Base_Type (Etype (Formal)) then
1367 Tagged_Type := Etype (Formal);
1370 Next_Formal (Formal);
1374 if Tagged_Type = Base_Type (Etype (Old_Subp)) then
1375 Tagged_Type := Etype (Old_Subp);
1379 Check_Controlling_Formals (Tagged_Type, Old_Subp);
1380 Set_Is_Dispatching_Operation (Old_Subp, True);
1381 Set_DT_Position (Old_Subp, No_Uint);
1384 -- If the old subprogram is an explicit renaming of some other
1385 -- entity, it is not overridden by the inherited subprogram.
1386 -- Otherwise, update its alias and other attributes.
1388 if Present (Alias (Old_Subp))
1389 and then Nkind (Unit_Declaration_Node (Old_Subp)) /=
1390 N_Subprogram_Renaming_Declaration
1392 Set_Alias (Old_Subp, Alias (Subp));
1394 -- The derived subprogram should inherit the abstractness
1395 -- of the parent subprogram (except in the case of a function
1396 -- returning the type). This sets the abstractness properly
1397 -- for cases where a private extension may have inherited
1398 -- an abstract operation, but the full type is derived from
1399 -- a descendant type and inherits a nonabstract version.
1401 if Etype (Subp) /= Tagged_Type then
1402 Set_Is_Abstract_Subprogram
1403 (Old_Subp, Is_Abstract_Subprogram (Alias (Subp)));
1408 end Check_Operation_From_Private_View;
1410 --------------------------
1411 -- Find_Controlling_Arg --
1412 --------------------------
1414 function Find_Controlling_Arg (N : Node_Id) return Node_Id is
1415 Orig_Node : constant Node_Id := Original_Node (N);
1419 if Nkind (Orig_Node) = N_Qualified_Expression then
1420 return Find_Controlling_Arg (Expression (Orig_Node));
1423 -- Dispatching on result case. If expansion is disabled, the node still
1424 -- has the structure of a function call. However, if the function name
1425 -- is an operator and the call was given in infix form, the original
1426 -- node has no controlling result and we must examine the current node.
1428 if Nkind (N) = N_Function_Call
1429 and then Present (Controlling_Argument (N))
1430 and then Has_Controlling_Result (Entity (Name (N)))
1432 return Controlling_Argument (N);
1434 -- If expansion is enabled, the call may have been transformed into
1435 -- an indirect call, and we need to recover the original node.
1437 elsif Nkind (Orig_Node) = N_Function_Call
1438 and then Present (Controlling_Argument (Orig_Node))
1439 and then Has_Controlling_Result (Entity (Name (Orig_Node)))
1441 return Controlling_Argument (Orig_Node);
1445 elsif Is_Controlling_Actual (N)
1447 (Nkind (Parent (N)) = N_Qualified_Expression
1448 and then Is_Controlling_Actual (Parent (N)))
1452 if Is_Access_Type (Typ) then
1454 -- In the case of an Access attribute, use the type of the prefix,
1455 -- since in the case of an actual for an access parameter, the
1456 -- attribute's type may be of a specific designated type, even
1457 -- though the prefix type is class-wide.
1459 if Nkind (N) = N_Attribute_Reference then
1460 Typ := Etype (Prefix (N));
1462 -- An allocator is dispatching if the type of qualified expression
1463 -- is class_wide, in which case this is the controlling type.
1465 elsif Nkind (Orig_Node) = N_Allocator
1466 and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression
1468 Typ := Etype (Expression (Orig_Node));
1470 Typ := Designated_Type (Typ);
1474 if Is_Class_Wide_Type (Typ)
1476 (Nkind (Parent (N)) = N_Qualified_Expression
1477 and then Is_Access_Type (Etype (N))
1478 and then Is_Class_Wide_Type (Designated_Type (Etype (N))))
1485 end Find_Controlling_Arg;
1487 ---------------------------
1488 -- Find_Dispatching_Type --
1489 ---------------------------
1491 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is
1492 A_Formal : Entity_Id;
1494 Ctrl_Type : Entity_Id;
1497 if Present (DTC_Entity (Subp)) then
1498 return Scope (DTC_Entity (Subp));
1500 -- For subprograms internally generated by derivations of tagged types
1501 -- use the alias subprogram as a reference to locate the dispatching
1504 elsif not Comes_From_Source (Subp)
1505 and then Present (Alias (Subp))
1506 and then Is_Dispatching_Operation (Alias (Subp))
1508 if Ekind (Alias (Subp)) = E_Function
1509 and then Has_Controlling_Result (Alias (Subp))
1511 return Check_Controlling_Type (Etype (Subp), Subp);
1514 Formal := First_Formal (Subp);
1515 A_Formal := First_Formal (Alias (Subp));
1516 while Present (A_Formal) loop
1517 if Is_Controlling_Formal (A_Formal) then
1518 return Check_Controlling_Type (Etype (Formal), Subp);
1521 Next_Formal (Formal);
1522 Next_Formal (A_Formal);
1525 pragma Assert (False);
1532 Formal := First_Formal (Subp);
1533 while Present (Formal) loop
1534 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
1536 if Present (Ctrl_Type) then
1540 Next_Formal (Formal);
1543 -- The subprogram may also be dispatching on result
1545 if Present (Etype (Subp)) then
1546 return Check_Controlling_Type (Etype (Subp), Subp);
1550 pragma Assert (not Is_Dispatching_Operation (Subp));
1552 end Find_Dispatching_Type;
1554 ---------------------------------------
1555 -- Find_Primitive_Covering_Interface --
1556 ---------------------------------------
1558 function Find_Primitive_Covering_Interface
1559 (Tagged_Type : Entity_Id;
1560 Iface_Prim : Entity_Id) return Entity_Id
1565 pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim))
1566 or else (Present (Alias (Iface_Prim))
1569 (Find_Dispatching_Type (Ultimate_Alias (Iface_Prim)))));
1571 E := Current_Entity (Iface_Prim);
1572 while Present (E) loop
1573 if Is_Subprogram (E)
1574 and then Is_Dispatching_Operation (E)
1575 and then Is_Interface_Conformant (Tagged_Type, Iface_Prim, E)
1584 end Find_Primitive_Covering_Interface;
1586 ---------------------------
1587 -- Is_Dynamically_Tagged --
1588 ---------------------------
1590 function Is_Dynamically_Tagged (N : Node_Id) return Boolean is
1592 if Nkind (N) = N_Error then
1595 return Find_Controlling_Arg (N) /= Empty;
1597 end Is_Dynamically_Tagged;
1599 --------------------------
1600 -- Is_Tag_Indeterminate --
1601 --------------------------
1603 function Is_Tag_Indeterminate (N : Node_Id) return Boolean is
1606 Orig_Node : constant Node_Id := Original_Node (N);
1609 if Nkind (Orig_Node) = N_Function_Call
1610 and then Is_Entity_Name (Name (Orig_Node))
1612 Nam := Entity (Name (Orig_Node));
1614 if not Has_Controlling_Result (Nam) then
1617 -- An explicit dereference means that the call has already been
1618 -- expanded and there is no tag to propagate.
1620 elsif Nkind (N) = N_Explicit_Dereference then
1623 -- If there are no actuals, the call is tag-indeterminate
1625 elsif No (Parameter_Associations (Orig_Node)) then
1629 Actual := First_Actual (Orig_Node);
1630 while Present (Actual) loop
1631 if Is_Controlling_Actual (Actual)
1632 and then not Is_Tag_Indeterminate (Actual)
1634 return False; -- one operand is dispatching
1637 Next_Actual (Actual);
1643 elsif Nkind (Orig_Node) = N_Qualified_Expression then
1644 return Is_Tag_Indeterminate (Expression (Orig_Node));
1646 -- Case of a call to the Input attribute (possibly rewritten), which is
1647 -- always tag-indeterminate except when its prefix is a Class attribute.
1649 elsif Nkind (Orig_Node) = N_Attribute_Reference
1651 Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input
1653 Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference
1657 -- In Ada 2005 a function that returns an anonymous access type can
1658 -- dispatching, and the dereference of a call to such a function
1659 -- is also tag-indeterminate.
1661 elsif Nkind (Orig_Node) = N_Explicit_Dereference
1662 and then Ada_Version >= Ada_05
1664 return Is_Tag_Indeterminate (Prefix (Orig_Node));
1669 end Is_Tag_Indeterminate;
1671 ------------------------------------
1672 -- Override_Dispatching_Operation --
1673 ------------------------------------
1675 procedure Override_Dispatching_Operation
1676 (Tagged_Type : Entity_Id;
1677 Prev_Op : Entity_Id;
1684 -- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but
1685 -- we do it unconditionally in Ada 95 now, since this is our pragma!)
1687 if No_Return (Prev_Op) and then not No_Return (New_Op) then
1688 Error_Msg_N ("procedure & must have No_Return pragma", New_Op);
1689 Error_Msg_N ("\since overridden procedure has No_Return", New_Op);
1692 -- If there is no previous operation to override, the type declaration
1693 -- was malformed, and an error must have been emitted already.
1695 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1696 while Present (Elmt)
1697 and then Node (Elmt) /= Prev_Op
1706 Replace_Elmt (Elmt, New_Op);
1708 if Ada_Version >= Ada_05
1709 and then Has_Interfaces (Tagged_Type)
1711 -- Ada 2005 (AI-251): Update the attribute alias of all the aliased
1712 -- entities of the overridden primitive to reference New_Op, and also
1713 -- propagate the proper value of Is_Abstract_Subprogram. Verify
1714 -- that the new operation is subtype conformant with the interface
1715 -- operations that it implements (for operations inherited from the
1716 -- parent itself, this check is made when building the derived type).
1718 -- Note: This code is only executed in case of late overriding
1720 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1721 while Present (Elmt) loop
1722 Prim := Node (Elmt);
1724 if Prim = New_Op then
1727 -- Note: The check on Is_Subprogram protects the frontend against
1728 -- reading attributes in entities that are not yet fully decorated
1730 elsif Is_Subprogram (Prim)
1731 and then Present (Interface_Alias (Prim))
1732 and then Alias (Prim) = Prev_Op
1733 and then Present (Etype (New_Op))
1735 Set_Alias (Prim, New_Op);
1736 Check_Subtype_Conformant (New_Op, Prim);
1737 Set_Is_Abstract_Subprogram (Prim,
1738 Is_Abstract_Subprogram (New_Op));
1740 -- Ensure that this entity will be expanded to fill the
1741 -- corresponding entry in its dispatch table.
1743 if not Is_Abstract_Subprogram (Prim) then
1744 Set_Has_Delayed_Freeze (Prim);
1752 if (not Is_Package_Or_Generic_Package (Current_Scope))
1753 or else not In_Private_Part (Current_Scope)
1755 -- Not a private primitive
1759 else pragma Assert (Is_Inherited_Operation (Prev_Op));
1761 -- Make the overriding operation into an alias of the implicit one.
1762 -- In this fashion a call from outside ends up calling the new body
1763 -- even if non-dispatching, and a call from inside calls the
1764 -- overriding operation because it hides the implicit one. To
1765 -- indicate that the body of Prev_Op is never called, set its
1766 -- dispatch table entity to Empty. If the overridden operation
1767 -- has a dispatching result, so does the overriding one.
1769 Set_Alias (Prev_Op, New_Op);
1770 Set_DTC_Entity (Prev_Op, Empty);
1771 Set_Has_Controlling_Result (New_Op, Has_Controlling_Result (Prev_Op));
1774 end Override_Dispatching_Operation;
1780 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is
1781 Call_Node : Node_Id;
1785 if Nkind (Actual) = N_Function_Call then
1786 Call_Node := Actual;
1788 elsif Nkind (Actual) = N_Identifier
1789 and then Nkind (Original_Node (Actual)) = N_Function_Call
1791 -- Call rewritten as object declaration when stack-checking is
1792 -- enabled. Propagate tag to expression in declaration, which is
1795 Call_Node := Expression (Parent (Entity (Actual)));
1797 -- Ada 2005: If this is a dereference of a call to a function with a
1798 -- dispatching access-result, the tag is propagated when the dereference
1799 -- itself is expanded (see exp_ch6.adb) and there is nothing else to do.
1801 elsif Nkind (Actual) = N_Explicit_Dereference
1802 and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call
1806 -- Only other possibilities are parenthesized or qualified expression,
1807 -- or an expander-generated unchecked conversion of a function call to
1808 -- a stream Input attribute.
1811 Call_Node := Expression (Actual);
1814 -- Do not set the Controlling_Argument if already set. This happens in
1815 -- the special case of _Input (see Exp_Attr, case Input).
1817 if No (Controlling_Argument (Call_Node)) then
1818 Set_Controlling_Argument (Call_Node, Control);
1821 Arg := First_Actual (Call_Node);
1823 while Present (Arg) loop
1824 if Is_Tag_Indeterminate (Arg) then
1825 Propagate_Tag (Control, Arg);
1831 -- Expansion of dispatching calls is suppressed when VM_Target, because
1832 -- the VM back-ends directly handle the generation of dispatching calls
1833 -- and would have to undo any expansion to an indirect call.
1835 if Tagged_Type_Expansion then
1836 Expand_Dispatching_Call (Call_Node);
1838 -- Expansion of a dispatching call results in an indirect call, which in
1839 -- turn causes current values to be killed (see Resolve_Call), so on VM
1840 -- targets we do the call here to ensure consistent warnings between VM
1841 -- and non-VM targets.
1844 Kill_Current_Values;