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Remove outermost loop parameter.
[official-gcc/graphite-test-results.git] / gcc / ada / sem_disp.adb
blob9c9da627ee09d6f2525b0c9439b55ff877440541
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT COMPILER COMPONENTS --
4 -- --
5 -- S E M _ D I S P --
6 -- --
7 -- B o d y --
8 -- --
9 -- Copyright (C) 1992-2009, Free Software Foundation, Inc. --
10 -- --
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. --
20 -- --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
23 -- --
24 ------------------------------------------------------------------------------
25
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;
39 with Opt; use Opt;
40 with Output; use Output;
41 with Restrict; use Restrict;
42 with Rident; use Rident;
43 with Sem; use Sem;
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;
54
55 package body Sem_Disp is
56
57 -----------------------
58 -- Local Subprograms --
59 -----------------------
60
61 procedure Add_Dispatching_Operation
62 (Tagged_Type : Entity_Id;
63 New_Op : Entity_Id);
64 -- Add New_Op in the list of primitive operations of Tagged_Type
65
66 function Check_Controlling_Type
67 (T : Entity_Id;
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.
74
75 -------------------------------
76 -- Add_Dispatching_Operation --
77 -------------------------------
78
79 procedure Add_Dispatching_Operation
80 (Tagged_Type : Entity_Id;
81 New_Op : Entity_Id)
82 is
83 List : constant Elist_Id := Primitive_Operations (Tagged_Type);
84
85 begin
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.
90
91 Append_Unique_Elmt (New_Op, List);
92 end Add_Dispatching_Operation;
93
94 -------------------------------
95 -- Check_Controlling_Formals --
96 -------------------------------
97
98 procedure Check_Controlling_Formals
99 (Typ : Entity_Id;
100 Subp : Entity_Id)
101 is
102 Formal : Entity_Id;
103 Ctrl_Type : Entity_Id;
104
105 begin
106 Formal := First_Formal (Subp);
107 while Present (Formal) loop
108 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
109
110 if Present (Ctrl_Type) then
111
112 -- When controlling type is concurrent and declared within a
113 -- generic or inside an instance use corresponding record type.
114
115 if Is_Concurrent_Type (Ctrl_Type)
116 and then Present (Corresponding_Record_Type (Ctrl_Type))
117 then
118 Ctrl_Type := Corresponding_Record_Type (Ctrl_Type);
119 end if;
120
121 if Ctrl_Type = Typ then
122 Set_Is_Controlling_Formal (Formal);
123
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.
127
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));
131 end if;
132
133 -- Check that the parameter's nominal subtype statically
134 -- matches the first subtype.
135
136 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
137 if not Subtypes_Statically_Match
138 (Typ, Designated_Type (Etype (Formal)))
139 then
140 Error_Msg_N
141 ("parameter subtype does not match controlling type",
142 Formal);
143 end if;
144
145 elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then
146 Error_Msg_N
147 ("parameter subtype does not match controlling type",
148 Formal);
149 end if;
150
151 if Present (Default_Value (Formal)) then
152
153 -- In Ada 2005, access parameters can have defaults
154
155 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
156 and then Ada_Version < Ada_05
157 then
158 Error_Msg_N
159 ("default not allowed for controlling access parameter",
160 Default_Value (Formal));
161
162 elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then
163 Error_Msg_N
164 ("default expression must be a tag indeterminate" &
165 " function call", Default_Value (Formal));
166 end if;
167 end if;
168
169 elsif Comes_From_Source (Subp) then
170 Error_Msg_N
171 ("operation can be dispatching in only one type", Subp);
172 end if;
173 end if;
174
175 Next_Formal (Formal);
176 end loop;
177
178 if Ekind (Subp) = E_Function
179 or else
180 Ekind (Subp) = E_Generic_Function
181 then
182 Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp);
183
184 if Present (Ctrl_Type) then
185 if Ctrl_Type = Typ then
186 Set_Has_Controlling_Result (Subp);
187
188 -- Check that result subtype statically matches first subtype
189 -- (Ada 2005): Subp may have a controlling access result.
190
191 if Subtypes_Statically_Match (Typ, Etype (Subp))
192 or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type
193 and then
194 Subtypes_Statically_Match
195 (Typ, Designated_Type (Etype (Subp))))
196 then
197 null;
198
199 else
200 Error_Msg_N
201 ("result subtype does not match controlling type", Subp);
202 end if;
203
204 elsif Comes_From_Source (Subp) then
205 Error_Msg_N
206 ("operation can be dispatching in only one type", Subp);
207 end if;
208 end if;
209 end if;
210 end Check_Controlling_Formals;
211
212 ----------------------------
213 -- Check_Controlling_Type --
214 ----------------------------
215
216 function Check_Controlling_Type
217 (T : Entity_Id;
218 Subp : Entity_Id) return Entity_Id
219 is
220 Tagged_Type : Entity_Id := Empty;
221
222 begin
223 if Is_Tagged_Type (T) then
224 if Is_First_Subtype (T) then
225 Tagged_Type := T;
226 else
227 Tagged_Type := Base_Type (T);
228 end if;
229
230 elsif Ekind (T) = E_Anonymous_Access_Type
231 and then Is_Tagged_Type (Designated_Type (T))
232 then
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);
236 else
237 Tagged_Type := Base_Type (Designated_Type (T));
238 end if;
239
240 -- Ada 2005: an incomplete type can be tagged. An operation with an
241 -- access parameter of the type is dispatching.
242
243 elsif Scope (Designated_Type (T)) = Current_Scope then
244 Tagged_Type := Designated_Type (T);
245
246 -- Ada 2005 (AI-50217)
247
248 elsif From_With_Type (Designated_Type (T))
249 and then Present (Non_Limited_View (Designated_Type (T)))
250 then
251 if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then
252 Tagged_Type := Non_Limited_View (Designated_Type (T));
253 else
254 Tagged_Type := Base_Type (Non_Limited_View
255 (Designated_Type (T)));
256 end if;
257 end if;
258 end if;
259
260 if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then
261 return Empty;
262
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.
266
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)))
270 or else
271 (Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp))
272 or else
273 (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration
274 and then
275 Present (Corresponding_Formal_Spec (Parent (Parent (Subp))))
276 and then
277 Is_Abstract_Subprogram (Subp))
278 then
279 return Tagged_Type;
280
281 else
282 return Empty;
283 end if;
284 end Check_Controlling_Type;
285
286 ----------------------------
287 -- Check_Dispatching_Call --
288 ----------------------------
289
290 procedure Check_Dispatching_Call (N : Node_Id) is
291 Loc : constant Source_Ptr := Sloc (N);
292 Actual : Node_Id;
293 Formal : Entity_Id;
294 Control : Node_Id := Empty;
295 Func : Entity_Id;
296 Subp_Entity : Entity_Id;
297 Indeterm_Ancestor_Call : Boolean := False;
298 Indeterm_Ctrl_Type : Entity_Id;
299
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.
303
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
308 -- call accordingly.
309
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.
314
315 -----------------------
316 -- Check_Direct_Call --
317 -----------------------
318
319 procedure Check_Direct_Call is
320 Typ : Entity_Id := Etype (Control);
321
322 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean;
323 -- Determine whether an entity denotes a user-defined equality
324
325 ------------------------------
326 -- Is_User_Defined_Equality --
327 ------------------------------
328
329 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is
330 begin
331 return
332 Ekind (Id) = E_Function
333 and then Chars (Id) = Name_Op_Eq
334 and then Comes_From_Source (Id)
335
336 -- Internally generated equalities have a full type declaration
337 -- as their parent.
338
339 and then Nkind (Parent (Id)) = N_Function_Specification;
340 end Is_User_Defined_Equality;
341
342 -- Start of processing for Check_Direct_Call
343
344 begin
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.
349
350 if Is_Predefined_Dispatching_Operation (Subp_Entity)
351 and then not Is_User_Defined_Equality (Subp_Entity)
352 then
353 return;
354 end if;
355
356 if Is_Class_Wide_Type (Typ) then
357 Typ := Root_Type (Typ);
358 end if;
359
360 if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
361 Typ := Full_View (Typ);
362 end if;
363
364 if Is_Concurrent_Type (Typ)
365 and then
366 Present (Corresponding_Record_Type (Typ))
367 then
368 Typ := Corresponding_Record_Type (Typ);
369
370 -- The concurrent record's list of primitives should contain a
371 -- wrapper for the entity of the call, retrieve it.
372
373 declare
374 Prim : Entity_Id;
375 Prim_Elmt : Elmt_Id;
376 Wrapper_Found : Boolean := False;
377
378 begin
379 Prim_Elmt := First_Elmt (Primitive_Operations (Typ));
380 while Present (Prim_Elmt) loop
381 Prim := Node (Prim_Elmt);
382
383 if Is_Primitive_Wrapper (Prim)
384 and then Wrapped_Entity (Prim) = Subp_Entity
385 then
386 Wrapper_Found := True;
387 exit;
388 end if;
389
390 Next_Elmt (Prim_Elmt);
391 end loop;
392
393 -- A primitive declared between two views should have a
394 -- corresponding wrapper.
395
396 pragma Assert (Wrapper_Found);
397
398 -- Modify the call by setting the proper entity
399
400 Set_Entity (Name (N), Prim);
401 end;
402 end if;
403 end Check_Direct_Call;
404
405 -------------------------------
406 -- Check_Dispatching_Context --
407 -------------------------------
408
409 procedure Check_Dispatching_Context is
410 Subp : constant Entity_Id := Entity (Name (N));
411 Par : Node_Id;
412
413 begin
414 if Is_Abstract_Subprogram (Subp)
415 and then No (Controlling_Argument (N))
416 then
417 if Present (Alias (Subp))
418 and then not Is_Abstract_Subprogram (Alias (Subp))
419 and then No (DTC_Entity (Subp))
420 then
421 -- Private overriding of inherited abstract operation, call is
422 -- legal.
423
424 Set_Entity (Name (N), Alias (Subp));
425 return;
426
427 else
428 Par := Parent (N);
429 while Present (Par) loop
430 if Nkind_In (Par, N_Function_Call,
431 N_Procedure_Call_Statement,
432 N_Assignment_Statement,
433 N_Op_Eq,
434 N_Op_Ne)
435 and then Is_Tagged_Type (Etype (Subp))
436 then
437 return;
438
439 elsif Nkind (Par) = N_Qualified_Expression
440 or else Nkind (Par) = N_Unchecked_Type_Conversion
441 then
442 Par := Parent (Par);
443
444 else
445 if Ekind (Subp) = E_Function then
446 Error_Msg_N
447 ("call to abstract function must be dispatching", N);
448
449 -- This error can occur for a procedure in the case of a
450 -- call to an abstract formal procedure with a statically
451 -- tagged operand.
452
453 else
454 Error_Msg_N
455 ("call to abstract procedure must be dispatching",
456 N);
457 end if;
458
459 return;
460 end if;
461 end loop;
462 end if;
463 end if;
464 end Check_Dispatching_Context;
465
466 -- Start of processing for Check_Dispatching_Call
467
468 begin
469 -- Find a controlling argument, if any
470
471 if Present (Parameter_Associations (N)) then
472 Subp_Entity := Entity (Name (N));
473
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);
479
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.
483
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))
488 then
489 Indeterm_Ancestor_Call := True;
490 Indeterm_Ctrl_Type := Etype (Formal);
491
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.
495
496 elsif Is_Controlling_Formal (Formal)
497 and then Is_Entity_Name (Actual)
498 and then Is_Tagged_Type (Etype (Actual))
499 then
500 Static_Tag := Actual;
501 end if;
502
503 Next_Actual (Actual);
504 Next_Formal (Formal);
505 end loop;
506
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).
515
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.
520
521 if No (Control)
522 and then Indeterm_Ancestor_Call
523 and then No (Static_Tag)
524 then
525 Control :=
526 Make_Attribute_Reference (Loc,
527 Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc),
528 Attribute_Name => Name_Tag);
529
530 Analyze (Control);
531 end if;
532
533 if Present (Control) then
534
535 -- Verify that no controlling arguments are statically tagged
536
537 if Debug_Flag_E then
538 Write_Str ("Found Dispatching call");
539 Write_Int (Int (N));
540 Write_Eol;
541 end if;
542
543 Actual := First_Actual (N);
544 while Present (Actual) loop
545 if Actual /= Control then
546
547 if not Is_Controlling_Actual (Actual) then
548 null; -- Can be anything
549
550 elsif Is_Dynamically_Tagged (Actual) then
551 null; -- Valid parameter
552
553 elsif Is_Tag_Indeterminate (Actual) then
554
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
559 -- dispatching.
560
561 Propagate_Tag (Control, Actual);
562
563 else
564 Error_Msg_N
565 ("controlling argument is not dynamically tagged",
566 Actual);
567 return;
568 end if;
569 end if;
570
571 Next_Actual (Actual);
572 end loop;
573
574 -- Mark call as a dispatching call
575
576 Set_Controlling_Argument (N, Control);
577 Check_Restriction (No_Dispatching_Calls, N);
578
579 -- The dispatching call may need to be converted into a direct
580 -- call in certain cases.
581
582 Check_Direct_Call;
583
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).
588
589 elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then
590 Control :=
591 Make_Attribute_Reference (Loc,
592 Prefix =>
593 New_Occurrence_Of (Etype (Static_Tag), Loc),
594 Attribute_Name => Name_Tag);
595
596 Analyze (Control);
597
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)
603 then
604 Propagate_Tag (Control, Actual);
605 end if;
606
607 Next_Actual (Actual);
608 Next_Formal (Formal);
609 end loop;
610
611 Check_Dispatching_Context;
612
613 else
614 -- The call is not dispatching, so check that there aren't any
615 -- tag-indeterminate abstract calls left.
616
617 Actual := First_Actual (N);
618 while Present (Actual) loop
619 if Is_Tag_Indeterminate (Actual) then
620
621 -- Function call case
622
623 if Nkind (Original_Node (Actual)) = N_Function_Call then
624 Func := Entity (Name (Original_Node (Actual)));
625
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).
629
630 elsif
631 Nkind (Original_Node (Actual)) = N_Attribute_Reference
632 then
633 Func := Empty;
634
635 -- Only other possibility is a qualified expression whose
636 -- constituent expression is itself a call.
637
638 else
639 Func :=
640 Entity (Name
641 (Original_Node
642 (Expression (Original_Node (Actual)))));
643 end if;
644
645 if Present (Func) and then Is_Abstract_Subprogram (Func) then
646 Error_Msg_N (
647 "call to abstract function must be dispatching", N);
648 end if;
649 end if;
650
651 Next_Actual (Actual);
652 end loop;
653
654 Check_Dispatching_Context;
655 end if;
656
657 else
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.
661
662 Check_Dispatching_Context;
663 end if;
664 end Check_Dispatching_Call;
665
666 ---------------------------------
667 -- Check_Dispatching_Operation --
668 ---------------------------------
669
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;
674
675 begin
676 if Ekind (Subp) /= E_Procedure and then Ekind (Subp) /= E_Function then
677 return;
678 end if;
679
680 Set_Is_Dispatching_Operation (Subp, False);
681 Tagged_Type := Find_Dispatching_Type (Subp);
682
683 -- Ada 2005 (AI-345)
684
685 if Ada_Version = Ada_05
686 and then Present (Tagged_Type)
687 and then Is_Concurrent_Type (Tagged_Type)
688 then
689 -- Protect the frontend against previously detected errors
690
691 if No (Corresponding_Record_Type (Tagged_Type)) then
692 return;
693 end if;
694
695 Tagged_Type := Corresponding_Record_Type (Tagged_Type);
696 end if;
697
698 -- (AI-345): The task body procedure is not a primitive of the tagged
699 -- type
700
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))
707 then
708 return;
709 end if;
710
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.
716
717 Has_Dispatching_Parent :=
718 Present (Alias (Subp))
719 and then Is_Dispatching_Operation (Alias (Subp));
720
721 if No (Tagged_Type) then
722
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.
727
728 declare
729 E : Entity_Id;
730 Typ : Entity_Id;
731
732 begin
733 E := First_Entity (Subp);
734 while Present (E) loop
735
736 -- For an access parameter, check designated type
737
738 if Ekind (Etype (E)) = E_Anonymous_Access_Type then
739 Typ := Designated_Type (Etype (E));
740 else
741 Typ := Etype (E);
742 end if;
743
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
750 then
751 Error_Msg_N ("?declaration of& is too late!", Subp);
752 Error_Msg_NE
753 ("\spec should appear immediately after declaration of &!",
754 Subp, Typ);
755 exit;
756 end if;
757
758 Next_Entity (E);
759 end loop;
760
761 -- In case of functions check also the result type
762
763 if Ekind (Subp) = E_Function then
764 if Is_Access_Type (Etype (Subp)) then
765 Typ := Designated_Type (Etype (Subp));
766 else
767 Typ := Etype (Subp);
768 end if;
769
770 if not Is_Class_Wide_Type (Typ)
771 and then Is_Interface (Typ)
772 and then not Is_Derived_Type (Typ)
773 then
774 Error_Msg_N ("?declaration of& is too late!", Subp);
775 Error_Msg_NE
776 ("\spec should appear immediately after declaration of &!",
777 Subp, Typ);
778 end if;
779 end if;
780 end;
781
782 return;
783
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.
788
789 elsif Is_Frozen (Tagged_Type)
790 and then not Comes_From_Source (Subp)
791 and then not Has_Dispatching_Parent
792 then
793 -- Complete decoration if internally built subprograms that override
794 -- a dispatching primitive. These entities correspond with the
795 -- following cases:
796
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.
802
803 -- 2. Subprograms associated with stream attributes (built by
804 -- New_Stream_Subprogram)
805
806 if Present (Old_Subp)
807 and then Is_Overriding_Operation (Subp)
808 and then Is_Dispatching_Operation (Old_Subp)
809 then
810 pragma Assert
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);
816
817 Set_Is_Dispatching_Operation (Subp);
818 end if;
819
820 return;
821
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.
824
825 elsif Is_Child_Unit (Subp) then
826 return;
827
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.
831
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
835 then
836 if not Comes_From_Source (Subp)
837 or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type))
838 then
839 null;
840
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.
847
848 elsif Present (Old_Subp)
849 and then Is_Dispatching_Operation (Old_Subp)
850 then
851 if Comes_From_Source (Subp)
852 and then
853 (Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body
854 or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub)
855 then
856 declare
857 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
858 Decl_Item : Node_Id;
859
860 begin
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.
871
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.
876
877 Decl_Item := Next (Parent (Tagged_Type));
878 while Present (Decl_Item)
879 and then (Decl_Item /= Subp_Body)
880 loop
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)
884 then
885 Error_Msg_N ("overriding of& is too late!", Subp);
886 Error_Msg_N
887 ("\spec should appear immediately after the type!",
888 Subp);
889 exit;
890 end if;
891
892 Next (Decl_Item);
893 end loop;
894
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.
898
899 if No (Decl_Item) then
900 Error_Msg_N ("overriding of& is too late!", Subp);
901 Error_Msg_N
902 ("\spec should appear immediately after the type!",
903 Subp);
904
905 elsif Is_Frozen (Subp) then
906
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.
914
915 Body_Is_Last_Primitive := True;
916
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));
920
921 if not Restriction_Active (No_Dispatching_Calls) then
922 if Building_Static_DT (Tagged_Type) then
923
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.
928
929 if Has_Dispatch_Table (Tagged_Type) then
930 Error_Msg_N
931 ("overriding of& is too late for building" &
932 " static dispatch tables!", Subp);
933 Error_Msg_N
934 ("\spec should appear immediately after" &
935 " the type!", Subp);
936 end if;
937
938 else
939 Insert_Actions_After (Subp_Body,
940 Register_Primitive (Sloc (Subp_Body),
941 Prim => Subp));
942 end if;
943
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.
948
949 Generate_Reference (Tagged_Type, Subp, 'P', False);
950 Override_Dispatching_Operation
951 (Tagged_Type, Old_Subp, Subp);
952 end if;
953 end if;
954 end if;
955 end;
956
957 else
958 Error_Msg_N ("overriding of& is too late!", Subp);
959 Error_Msg_N
960 ("\subprogram spec should appear immediately after the type!",
961 Subp);
962 end if;
963
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
967 -- (3.2.3(6)).
968
969 elsif not Is_Frozen (Tagged_Type) then
970 Error_Msg_N
971 ("?not dispatching (must be defined in a package spec)", Subp);
972 return;
973
974 -- When the type is frozen, it is legitimate to define a new
975 -- non-primitive operation.
976
977 else
978 return;
979 end if;
980
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
983
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);
986 Error_Msg_NE
987 ("?no primitive operations for& after this line",
988 Freeze_Node (Tagged_Type),
989 Tagged_Type);
990 return;
991 end if;
992
993 Check_Controlling_Formals (Tagged_Type, Subp);
994
995 -- Now it should be a correct primitive operation, put it in the list
996
997 if Present (Old_Subp) then
998
999 -- If the type has interfaces we complete this check after we set
1000 -- attribute Is_Dispatching_Operation.
1001
1002 Check_Subtype_Conformant (Subp, Old_Subp);
1003
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)
1009 then
1010 Set_Is_Overriding_Operation (Subp, False);
1011
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.
1015
1016 if Nkind (Parent (Subp)) = N_Procedure_Specification
1017 and then
1018 (Must_Override (Parent (Subp))
1019 or else Must_Not_Override (Parent (Subp)))
1020 then
1021 null;
1022
1023 -- Here we need the warning
1024
1025 else
1026 Error_Msg_NE
1027 ("operation does not override inherited&?", Subp, Subp);
1028 end if;
1029
1030 else
1031 Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp);
1032 Set_Is_Overriding_Operation (Subp);
1033
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.
1040
1041 if Body_Is_Last_Primitive then
1042 declare
1043 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
1044 Elmt : Elmt_Id;
1045 Prim : Node_Id;
1046
1047 begin
1048 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1049 while Present (Elmt) loop
1050 Prim := Node (Elmt);
1051
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)
1056 then
1057 Insert_Actions_After (Subp_Body,
1058 Register_Primitive (Sloc (Subp_Body), Prim => Prim));
1059 end if;
1060
1061 Next_Elmt (Elmt);
1062 end loop;
1063
1064 -- Redisplay the contents of the updated dispatch table
1065
1066 if Debug_Flag_ZZ then
1067 Write_Str ("Late overriding: ");
1068 Write_DT (Tagged_Type);
1069 end if;
1070 end;
1071 end if;
1072 end if;
1073
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
1076 -- cascaded errors.
1077
1078 elsif not Error_Posted (Subp) then
1079 Add_Dispatching_Operation (Tagged_Type, Subp);
1080 end if;
1081
1082 Set_Is_Dispatching_Operation (Subp, True);
1083
1084 -- Ada 2005 (AI-251): If the type implements interfaces we must check
1085 -- subtype conformance against all the interfaces covered by this
1086 -- primitive.
1087
1088 if Present (Old_Subp)
1089 and then Has_Interfaces (Tagged_Type)
1090 then
1091 declare
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;
1097
1098 begin
1099 Collect_Interfaces (Tagged_Type, Ifaces_List);
1100
1101 Iface_Elmt := First_Elmt (Ifaces_List);
1102 while Present (Iface_Elmt) loop
1103 if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then
1104 Iface_Prim_Elmt :=
1105 First_Elmt (Primitive_Operations (Node (Iface_Elmt)));
1106 while Present (Iface_Prim_Elmt) loop
1107 Iface_Prim := Node (Iface_Prim_Elmt);
1108
1109 if Is_Interface_Conformant
1110 (Tagged_Type, Iface_Prim, Subp)
1111 then
1112 -- Handle procedures, functions whose return type
1113 -- matches, or functions not returning interfaces
1114
1115 if Ekind (Subp) = E_Procedure
1116 or else Etype (Iface_Prim) = Etype (Subp)
1117 or else not Is_Interface (Etype (Iface_Prim))
1118 then
1119 Check_Subtype_Conformant
1120 (New_Id => Subp,
1121 Old_Id => Iface_Prim,
1122 Err_Loc => Subp,
1123 Skip_Controlling_Formals => True);
1124
1125 -- Handle functions returning interfaces
1126
1127 elsif Implements_Interface
1128 (Etype (Subp), Etype (Iface_Prim))
1129 then
1130 -- Temporarily force both entities to return the
1131 -- same type. Required because Subtype_Conformant
1132 -- does not handle this case.
1133
1134 Ret_Typ := Etype (Iface_Prim);
1135 Set_Etype (Iface_Prim, Etype (Subp));
1136
1137 Check_Subtype_Conformant
1138 (New_Id => Subp,
1139 Old_Id => Iface_Prim,
1140 Err_Loc => Subp,
1141 Skip_Controlling_Formals => True);
1142
1143 Set_Etype (Iface_Prim, Ret_Typ);
1144 end if;
1145 end if;
1146
1147 Next_Elmt (Iface_Prim_Elmt);
1148 end loop;
1149 end if;
1150
1151 Next_Elmt (Iface_Elmt);
1152 end loop;
1153 end;
1154 end if;
1155
1156 if not Body_Is_Last_Primitive then
1157 Set_DT_Position (Subp, No_Uint);
1158
1159 elsif Has_Controlled_Component (Tagged_Type)
1160 and then
1161 (Chars (Subp) = Name_Initialize
1162 or else
1163 Chars (Subp) = Name_Adjust
1164 or else
1165 Chars (Subp) = Name_Finalize)
1166 then
1167 declare
1168 F_Node : constant Node_Id := Freeze_Node (Tagged_Type);
1169 Decl : Node_Id;
1170 Old_P : Entity_Id;
1171 Old_Bod : Node_Id;
1172 Old_Spec : Entity_Id;
1173
1174 C_Names : constant array (1 .. 3) of Name_Id :=
1175 (Name_Initialize,
1176 Name_Adjust,
1177 Name_Finalize);
1178
1179 D_Names : constant array (1 .. 3) of TSS_Name_Type :=
1180 (TSS_Deep_Initialize,
1181 TSS_Deep_Adjust,
1182 TSS_Deep_Finalize);
1183
1184 begin
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.
1192
1193 for J in D_Names'Range loop
1194 Old_P := TSS (Tagged_Type, D_Names (J));
1195
1196 if Present (Old_P)
1197 and then Chars (Subp) = C_Names (J)
1198 then
1199 Old_Bod := Unit_Declaration_Node (Old_P);
1200 Remove (Old_Bod);
1201 Set_Is_Eliminated (Old_P);
1202 Set_Scope (Old_P, Scope (Current_Scope));
1203
1204 if Nkind (Old_Bod) = N_Subprogram_Body
1205 and then Present (Corresponding_Spec (Old_Bod))
1206 then
1207 Old_Spec := Corresponding_Spec (Old_Bod);
1208 Set_Has_Completion (Old_Spec, False);
1209 end if;
1210 end if;
1211 end loop;
1212
1213 Build_Late_Proc (Tagged_Type, Chars (Subp));
1214
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.
1218
1219 if Present (F_Node)
1220 and then Present (Actions (F_Node))
1221 then
1222 Decl := Last (Actions (F_Node));
1223 Analyze (Decl);
1224 end if;
1225 end;
1226 end if;
1227 end Check_Dispatching_Operation;
1228
1229 ------------------------------------------
1230 -- Check_Operation_From_Incomplete_Type --
1231 ------------------------------------------
1232
1233 procedure Check_Operation_From_Incomplete_Type
1234 (Subp : Entity_Id;
1235 Typ : Entity_Id)
1236 is
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);
1241 Op1, Op2 : Elmt_Id;
1242 Prev : Elmt_Id := No_Elmt;
1243
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.
1247
1248 ------------------
1249 -- Derives_From --
1250 ------------------
1251
1252 function Derives_From (Proc : Entity_Id) return Boolean is
1253 F1, F2 : Entity_Id;
1254
1255 begin
1256 if Chars (Proc) /= Chars (Subp) then
1257 return False;
1258 end if;
1259
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
1265 return False;
1266 elsif Designated_Type (Etype (F1)) = Parent_Typ
1267 and then Designated_Type (Etype (F2)) /= Full
1268 then
1269 return False;
1270 end if;
1271
1272 elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then
1273 return False;
1274
1275 elsif Etype (F1) /= Etype (F2) then
1276 return False;
1277 end if;
1278
1279 Next_Formal (F1);
1280 Next_Formal (F2);
1281 end loop;
1282
1283 return No (F1) and then No (F2);
1284 end Derives_From;
1285
1286 -- Start of processing for Check_Operation_From_Incomplete_Type
1287
1288 begin
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.
1295
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
1300 if No (Prev) then
1301
1302 -- Avoid adding it to the list of primitives if already there!
1303
1304 if Node (Op2) /= Subp then
1305 Prepend_Elmt (Subp, New_Prim);
1306 end if;
1307
1308 else
1309 Insert_Elmt_After (Subp, Prev);
1310 end if;
1311
1312 return;
1313 end if;
1314
1315 Prev := Op2;
1316 Next_Elmt (Op1);
1317 Next_Elmt (Op2);
1318 end loop;
1319
1320 -- Operation is a new primitive
1321
1322 Append_Elmt (Subp, New_Prim);
1323 end Check_Operation_From_Incomplete_Type;
1324
1325 ---------------------------------------
1326 -- Check_Operation_From_Private_View --
1327 ---------------------------------------
1328
1329 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is
1330 Tagged_Type : Entity_Id;
1331
1332 begin
1333 if Is_Dispatching_Operation (Alias (Subp)) then
1334 Set_Scope (Subp, Current_Scope);
1335 Tagged_Type := Find_Dispatching_Type (Subp);
1336
1337 -- Add Old_Subp to primitive operations if not already present
1338
1339 if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then
1340 Append_Unique_Elmt (Old_Subp, Primitive_Operations (Tagged_Type));
1341
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.
1347
1348 if not Is_Dispatching_Operation (Old_Subp) then
1349
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
1355 -- base type.
1356
1357 if not Comes_From_Source (Tagged_Type)
1358 and then Has_Discriminants (Tagged_Type)
1359 then
1360 declare
1361 Formal : Entity_Id;
1362
1363 begin
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);
1368 end if;
1369
1370 Next_Formal (Formal);
1371 end loop;
1372 end;
1373
1374 if Tagged_Type = Base_Type (Etype (Old_Subp)) then
1375 Tagged_Type := Etype (Old_Subp);
1376 end if;
1377 end if;
1378
1379 Check_Controlling_Formals (Tagged_Type, Old_Subp);
1380 Set_Is_Dispatching_Operation (Old_Subp, True);
1381 Set_DT_Position (Old_Subp, No_Uint);
1382 end if;
1383
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.
1387
1388 if Present (Alias (Old_Subp))
1389 and then Nkind (Unit_Declaration_Node (Old_Subp)) /=
1390 N_Subprogram_Renaming_Declaration
1391 then
1392 Set_Alias (Old_Subp, Alias (Subp));
1393
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.
1400
1401 if Etype (Subp) /= Tagged_Type then
1402 Set_Is_Abstract_Subprogram
1403 (Old_Subp, Is_Abstract_Subprogram (Alias (Subp)));
1404 end if;
1405 end if;
1406 end if;
1407 end if;
1408 end Check_Operation_From_Private_View;
1409
1410 --------------------------
1411 -- Find_Controlling_Arg --
1412 --------------------------
1413
1414 function Find_Controlling_Arg (N : Node_Id) return Node_Id is
1415 Orig_Node : constant Node_Id := Original_Node (N);
1416 Typ : Entity_Id;
1417
1418 begin
1419 if Nkind (Orig_Node) = N_Qualified_Expression then
1420 return Find_Controlling_Arg (Expression (Orig_Node));
1421 end if;
1422
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.
1427
1428 if Nkind (N) = N_Function_Call
1429 and then Present (Controlling_Argument (N))
1430 and then Has_Controlling_Result (Entity (Name (N)))
1431 then
1432 return Controlling_Argument (N);
1433
1434 -- If expansion is enabled, the call may have been transformed into
1435 -- an indirect call, and we need to recover the original node.
1436
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)))
1440 then
1441 return Controlling_Argument (Orig_Node);
1442
1443 -- Normal case
1444
1445 elsif Is_Controlling_Actual (N)
1446 or else
1447 (Nkind (Parent (N)) = N_Qualified_Expression
1448 and then Is_Controlling_Actual (Parent (N)))
1449 then
1450 Typ := Etype (N);
1451
1452 if Is_Access_Type (Typ) then
1453
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.
1458
1459 if Nkind (N) = N_Attribute_Reference then
1460 Typ := Etype (Prefix (N));
1461
1462 -- An allocator is dispatching if the type of qualified expression
1463 -- is class_wide, in which case this is the controlling type.
1464
1465 elsif Nkind (Orig_Node) = N_Allocator
1466 and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression
1467 then
1468 Typ := Etype (Expression (Orig_Node));
1469 else
1470 Typ := Designated_Type (Typ);
1471 end if;
1472 end if;
1473
1474 if Is_Class_Wide_Type (Typ)
1475 or else
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))))
1479 then
1480 return N;
1481 end if;
1482 end if;
1483
1484 return Empty;
1485 end Find_Controlling_Arg;
1486
1487 ---------------------------
1488 -- Find_Dispatching_Type --
1489 ---------------------------
1490
1491 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is
1492 A_Formal : Entity_Id;
1493 Formal : Entity_Id;
1494 Ctrl_Type : Entity_Id;
1495
1496 begin
1497 if Present (DTC_Entity (Subp)) then
1498 return Scope (DTC_Entity (Subp));
1499
1500 -- For subprograms internally generated by derivations of tagged types
1501 -- use the alias subprogram as a reference to locate the dispatching
1502 -- type of Subp
1503
1504 elsif not Comes_From_Source (Subp)
1505 and then Present (Alias (Subp))
1506 and then Is_Dispatching_Operation (Alias (Subp))
1507 then
1508 if Ekind (Alias (Subp)) = E_Function
1509 and then Has_Controlling_Result (Alias (Subp))
1510 then
1511 return Check_Controlling_Type (Etype (Subp), Subp);
1512
1513 else
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);
1519 end if;
1520
1521 Next_Formal (Formal);
1522 Next_Formal (A_Formal);
1523 end loop;
1524
1525 pragma Assert (False);
1526 return Empty;
1527 end if;
1528
1529 -- General case
1530
1531 else
1532 Formal := First_Formal (Subp);
1533 while Present (Formal) loop
1534 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
1535
1536 if Present (Ctrl_Type) then
1537 return Ctrl_Type;
1538 end if;
1539
1540 Next_Formal (Formal);
1541 end loop;
1542
1543 -- The subprogram may also be dispatching on result
1544
1545 if Present (Etype (Subp)) then
1546 return Check_Controlling_Type (Etype (Subp), Subp);
1547 end if;
1548 end if;
1549
1550 pragma Assert (not Is_Dispatching_Operation (Subp));
1551 return Empty;
1552 end Find_Dispatching_Type;
1553
1554 ---------------------------------------
1555 -- Find_Primitive_Covering_Interface --
1556 ---------------------------------------
1557
1558 function Find_Primitive_Covering_Interface
1559 (Tagged_Type : Entity_Id;
1560 Iface_Prim : Entity_Id) return Entity_Id
1561 is
1562 E : Entity_Id;
1563
1564 begin
1565 pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim))
1566 or else (Present (Alias (Iface_Prim))
1567 and then
1568 Is_Interface
1569 (Find_Dispatching_Type (Ultimate_Alias (Iface_Prim)))));
1570
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)
1576 then
1577 return E;
1578 end if;
1579
1580 E := Homonym (E);
1581 end loop;
1582
1583 return Empty;
1584 end Find_Primitive_Covering_Interface;
1585
1586 ---------------------------
1587 -- Is_Dynamically_Tagged --
1588 ---------------------------
1589
1590 function Is_Dynamically_Tagged (N : Node_Id) return Boolean is
1591 begin
1592 if Nkind (N) = N_Error then
1593 return False;
1594 else
1595 return Find_Controlling_Arg (N) /= Empty;
1596 end if;
1597 end Is_Dynamically_Tagged;
1598
1599 --------------------------
1600 -- Is_Tag_Indeterminate --
1601 --------------------------
1602
1603 function Is_Tag_Indeterminate (N : Node_Id) return Boolean is
1604 Nam : Entity_Id;
1605 Actual : Node_Id;
1606 Orig_Node : constant Node_Id := Original_Node (N);
1607
1608 begin
1609 if Nkind (Orig_Node) = N_Function_Call
1610 and then Is_Entity_Name (Name (Orig_Node))
1611 then
1612 Nam := Entity (Name (Orig_Node));
1613
1614 if not Has_Controlling_Result (Nam) then
1615 return False;
1616
1617 -- An explicit dereference means that the call has already been
1618 -- expanded and there is no tag to propagate.
1619
1620 elsif Nkind (N) = N_Explicit_Dereference then
1621 return False;
1622
1623 -- If there are no actuals, the call is tag-indeterminate
1624
1625 elsif No (Parameter_Associations (Orig_Node)) then
1626 return True;
1627
1628 else
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)
1633 then
1634 return False; -- one operand is dispatching
1635 end if;
1636
1637 Next_Actual (Actual);
1638 end loop;
1639
1640 return True;
1641 end if;
1642
1643 elsif Nkind (Orig_Node) = N_Qualified_Expression then
1644 return Is_Tag_Indeterminate (Expression (Orig_Node));
1645
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.
1648
1649 elsif Nkind (Orig_Node) = N_Attribute_Reference
1650 and then
1651 Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input
1652 and then
1653 Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference
1654 then
1655 return True;
1656
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.
1660
1661 elsif Nkind (Orig_Node) = N_Explicit_Dereference
1662 and then Ada_Version >= Ada_05
1663 then
1664 return Is_Tag_Indeterminate (Prefix (Orig_Node));
1665
1666 else
1667 return False;
1668 end if;
1669 end Is_Tag_Indeterminate;
1670
1671 ------------------------------------
1672 -- Override_Dispatching_Operation --
1673 ------------------------------------
1674
1675 procedure Override_Dispatching_Operation
1676 (Tagged_Type : Entity_Id;
1677 Prev_Op : Entity_Id;
1678 New_Op : Entity_Id)
1679 is
1680 Elmt : Elmt_Id;
1681 Prim : Node_Id;
1682
1683 begin
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!)
1686
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);
1690 end if;
1691
1692 -- If there is no previous operation to override, the type declaration
1693 -- was malformed, and an error must have been emitted already.
1694
1695 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1696 while Present (Elmt)
1697 and then Node (Elmt) /= Prev_Op
1698 loop
1699 Next_Elmt (Elmt);
1700 end loop;
1701
1702 if No (Elmt) then
1703 return;
1704 end if;
1705
1706 Replace_Elmt (Elmt, New_Op);
1707
1708 if Ada_Version >= Ada_05
1709 and then Has_Interfaces (Tagged_Type)
1710 then
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).
1717
1718 -- Note: This code is only executed in case of late overriding
1719
1720 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1721 while Present (Elmt) loop
1722 Prim := Node (Elmt);
1723
1724 if Prim = New_Op then
1725 null;
1726
1727 -- Note: The check on Is_Subprogram protects the frontend against
1728 -- reading attributes in entities that are not yet fully decorated
1729
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))
1734 then
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));
1739
1740 -- Ensure that this entity will be expanded to fill the
1741 -- corresponding entry in its dispatch table.
1742
1743 if not Is_Abstract_Subprogram (Prim) then
1744 Set_Has_Delayed_Freeze (Prim);
1745 end if;
1746 end if;
1747
1748 Next_Elmt (Elmt);
1749 end loop;
1750 end if;
1751
1752 if (not Is_Package_Or_Generic_Package (Current_Scope))
1753 or else not In_Private_Part (Current_Scope)
1754 then
1755 -- Not a private primitive
1756
1757 null;
1758
1759 else pragma Assert (Is_Inherited_Operation (Prev_Op));
1760
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.
1768
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));
1772 return;
1773 end if;
1774 end Override_Dispatching_Operation;
1775
1776 -------------------
1777 -- Propagate_Tag --
1778 -------------------
1779
1780 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is
1781 Call_Node : Node_Id;
1782 Arg : Node_Id;
1783
1784 begin
1785 if Nkind (Actual) = N_Function_Call then
1786 Call_Node := Actual;
1787
1788 elsif Nkind (Actual) = N_Identifier
1789 and then Nkind (Original_Node (Actual)) = N_Function_Call
1790 then
1791 -- Call rewritten as object declaration when stack-checking is
1792 -- enabled. Propagate tag to expression in declaration, which is
1793 -- original call.
1794
1795 Call_Node := Expression (Parent (Entity (Actual)));
1796
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.
1800
1801 elsif Nkind (Actual) = N_Explicit_Dereference
1802 and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call
1803 then
1804 return;
1805
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.
1809
1810 else
1811 Call_Node := Expression (Actual);
1812 end if;
1813
1814 -- Do not set the Controlling_Argument if already set. This happens in
1815 -- the special case of _Input (see Exp_Attr, case Input).
1816
1817 if No (Controlling_Argument (Call_Node)) then
1818 Set_Controlling_Argument (Call_Node, Control);
1819 end if;
1820
1821 Arg := First_Actual (Call_Node);
1822
1823 while Present (Arg) loop
1824 if Is_Tag_Indeterminate (Arg) then
1825 Propagate_Tag (Control, Arg);
1826 end if;
1827
1828 Next_Actual (Arg);
1829 end loop;
1830
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.
1834
1835 if Tagged_Type_Expansion then
1836 Expand_Dispatching_Call (Call_Node);
1837
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.
1842
1843 else
1844 Kill_Current_Values;
1845 end if;
1846 end Propagate_Tag;
1847
1848 end Sem_Disp;
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