?  search:
summary | log | graphiclog1 | graphiclog2 | commit | commitdiff | tree | refs | edit | fork
blame | history | raw | HEAD
2009-07-17 Richard Guenther <rguenther@suse.de>
[official-gcc.git] / gcc / ada / sem_disp.adb
blob705f428716ac92b7c505f42d801960518c755129
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 Stand; use Stand;
52 with Sinfo; use Sinfo;
53 with Tbuild; use Tbuild;
54 with Uintp; use Uintp;
55
56 package body Sem_Disp is
57
58 -----------------------
59 -- Local Subprograms --
60 -----------------------
61
62 procedure Add_Dispatching_Operation
63 (Tagged_Type : Entity_Id;
64 New_Op : Entity_Id);
65 -- Add New_Op in the list of primitive operations of Tagged_Type
66
67 function Check_Controlling_Type
68 (T : Entity_Id;
69 Subp : Entity_Id) return Entity_Id;
70 -- T is the tagged type of a formal parameter or the result of Subp.
71 -- If the subprogram has a controlling parameter or result that matches
72 -- the type, then returns the tagged type of that parameter or result
73 -- (returning the designated tagged type in the case of an access
74 -- parameter); otherwise returns empty.
75
76 -------------------------------
77 -- Add_Dispatching_Operation --
78 -------------------------------
79
80 procedure Add_Dispatching_Operation
81 (Tagged_Type : Entity_Id;
82 New_Op : Entity_Id)
83 is
84 List : constant Elist_Id := Primitive_Operations (Tagged_Type);
85
86 begin
87 -- The dispatching operation may already be on the list, if it is the
88 -- wrapper for an inherited function of a null extension (see Exp_Ch3
89 -- for the construction of function wrappers). The list of primitive
90 -- operations must not contain duplicates.
91
92 Append_Unique_Elmt (New_Op, List);
93 end Add_Dispatching_Operation;
94
95 -------------------------------
96 -- Check_Controlling_Formals --
97 -------------------------------
98
99 procedure Check_Controlling_Formals
100 (Typ : Entity_Id;
101 Subp : Entity_Id)
102 is
103 Formal : Entity_Id;
104 Ctrl_Type : Entity_Id;
105
106 begin
107 Formal := First_Formal (Subp);
108 while Present (Formal) loop
109 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
110
111 if Present (Ctrl_Type) then
112
113 -- When controlling type is concurrent and declared within a
114 -- generic or inside an instance use corresponding record type.
115
116 if Is_Concurrent_Type (Ctrl_Type)
117 and then Present (Corresponding_Record_Type (Ctrl_Type))
118 then
119 Ctrl_Type := Corresponding_Record_Type (Ctrl_Type);
120 end if;
121
122 if Ctrl_Type = Typ then
123 Set_Is_Controlling_Formal (Formal);
124
125 -- Ada 2005 (AI-231): Anonymous access types that are used in
126 -- controlling parameters exclude null because it is necessary
127 -- to read the tag to dispatch, and null has no tag.
128
129 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
130 Set_Can_Never_Be_Null (Etype (Formal));
131 Set_Is_Known_Non_Null (Etype (Formal));
132 end if;
133
134 -- Check that the parameter's nominal subtype statically
135 -- matches the first subtype.
136
137 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then
138 if not Subtypes_Statically_Match
139 (Typ, Designated_Type (Etype (Formal)))
140 then
141 Error_Msg_N
142 ("parameter subtype does not match controlling type",
143 Formal);
144 end if;
145
146 elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then
147 Error_Msg_N
148 ("parameter subtype does not match controlling type",
149 Formal);
150 end if;
151
152 if Present (Default_Value (Formal)) then
153
154 -- In Ada 2005, access parameters can have defaults
155
156 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type
157 and then Ada_Version < Ada_05
158 then
159 Error_Msg_N
160 ("default not allowed for controlling access parameter",
161 Default_Value (Formal));
162
163 elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then
164 Error_Msg_N
165 ("default expression must be a tag indeterminate" &
166 " function call", Default_Value (Formal));
167 end if;
168 end if;
169
170 elsif Comes_From_Source (Subp) then
171 Error_Msg_N
172 ("operation can be dispatching in only one type", Subp);
173 end if;
174 end if;
175
176 Next_Formal (Formal);
177 end loop;
178
179 if Ekind (Subp) = E_Function
180 or else
181 Ekind (Subp) = E_Generic_Function
182 then
183 Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp);
184
185 if Present (Ctrl_Type) then
186 if Ctrl_Type = Typ then
187 Set_Has_Controlling_Result (Subp);
188
189 -- Check that result subtype statically matches first subtype
190 -- (Ada 2005): Subp may have a controlling access result.
191
192 if Subtypes_Statically_Match (Typ, Etype (Subp))
193 or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type
194 and then
195 Subtypes_Statically_Match
196 (Typ, Designated_Type (Etype (Subp))))
197 then
198 null;
199
200 else
201 Error_Msg_N
202 ("result subtype does not match controlling type", Subp);
203 end if;
204
205 elsif Comes_From_Source (Subp) then
206 Error_Msg_N
207 ("operation can be dispatching in only one type", Subp);
208 end if;
209 end if;
210 end if;
211 end Check_Controlling_Formals;
212
213 ----------------------------
214 -- Check_Controlling_Type --
215 ----------------------------
216
217 function Check_Controlling_Type
218 (T : Entity_Id;
219 Subp : Entity_Id) return Entity_Id
220 is
221 Tagged_Type : Entity_Id := Empty;
222
223 begin
224 if Is_Tagged_Type (T) then
225 if Is_First_Subtype (T) then
226 Tagged_Type := T;
227 else
228 Tagged_Type := Base_Type (T);
229 end if;
230
231 elsif Ekind (T) = E_Anonymous_Access_Type
232 and then Is_Tagged_Type (Designated_Type (T))
233 then
234 if Ekind (Designated_Type (T)) /= E_Incomplete_Type then
235 if Is_First_Subtype (Designated_Type (T)) then
236 Tagged_Type := Designated_Type (T);
237 else
238 Tagged_Type := Base_Type (Designated_Type (T));
239 end if;
240
241 -- Ada 2005: an incomplete type can be tagged. An operation with an
242 -- access parameter of the type is dispatching.
243
244 elsif Scope (Designated_Type (T)) = Current_Scope then
245 Tagged_Type := Designated_Type (T);
246
247 -- Ada 2005 (AI-50217)
248
249 elsif From_With_Type (Designated_Type (T))
250 and then Present (Non_Limited_View (Designated_Type (T)))
251 then
252 if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then
253 Tagged_Type := Non_Limited_View (Designated_Type (T));
254 else
255 Tagged_Type := Base_Type (Non_Limited_View
256 (Designated_Type (T)));
257 end if;
258 end if;
259 end if;
260
261 if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then
262 return Empty;
263
264 -- The dispatching type and the primitive operation must be defined in
265 -- the same scope, except in the case of internal operations and formal
266 -- abstract subprograms.
267
268 elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp))
269 and then (not Is_Generic_Type (Tagged_Type)
270 or else not Comes_From_Source (Subp)))
271 or else
272 (Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp))
273 or else
274 (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration
275 and then
276 Present (Corresponding_Formal_Spec (Parent (Parent (Subp))))
277 and then
278 Is_Abstract_Subprogram (Subp))
279 then
280 return Tagged_Type;
281
282 else
283 return Empty;
284 end if;
285 end Check_Controlling_Type;
286
287 ----------------------------
288 -- Check_Dispatching_Call --
289 ----------------------------
290
291 procedure Check_Dispatching_Call (N : Node_Id) is
292 Loc : constant Source_Ptr := Sloc (N);
293 Actual : Node_Id;
294 Formal : Entity_Id;
295 Control : Node_Id := Empty;
296 Func : Entity_Id;
297 Subp_Entity : Entity_Id;
298 Indeterm_Ancestor_Call : Boolean := False;
299 Indeterm_Ctrl_Type : Entity_Id;
300
301 Static_Tag : Node_Id := Empty;
302 -- If a controlling formal has a statically tagged actual, the tag of
303 -- this actual is to be used for any tag-indeterminate actual.
304
305 procedure Check_Direct_Call;
306 -- In the case when the controlling actual is a class-wide type whose
307 -- root type's completion is a task or protected type, the call is in
308 -- fact direct. This routine detects the above case and modifies the
309 -- call accordingly.
310
311 procedure Check_Dispatching_Context;
312 -- If the call is tag-indeterminate and the entity being called is
313 -- abstract, verify that the context is a call that will eventually
314 -- provide a tag for dispatching, or has provided one already.
315
316 -----------------------
317 -- Check_Direct_Call --
318 -----------------------
319
320 procedure Check_Direct_Call is
321 Typ : Entity_Id := Etype (Control);
322
323 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean;
324 -- Determine whether an entity denotes a user-defined equality
325
326 ------------------------------
327 -- Is_User_Defined_Equality --
328 ------------------------------
329
330 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is
331 begin
332 return
333 Ekind (Id) = E_Function
334 and then Chars (Id) = Name_Op_Eq
335 and then Comes_From_Source (Id)
336
337 -- Internally generated equalities have a full type declaration
338 -- as their parent.
339
340 and then Nkind (Parent (Id)) = N_Function_Specification;
341 end Is_User_Defined_Equality;
342
343 -- Start of processing for Check_Direct_Call
344
345 begin
346 -- Predefined primitives do not receive wrappers since they are built
347 -- from scratch for the corresponding record of synchronized types.
348 -- Equality is in general predefined, but is excluded from the check
349 -- when it is user-defined.
350
351 if Is_Predefined_Dispatching_Operation (Subp_Entity)
352 and then not Is_User_Defined_Equality (Subp_Entity)
353 then
354 return;
355 end if;
356
357 if Is_Class_Wide_Type (Typ) then
358 Typ := Root_Type (Typ);
359 end if;
360
361 if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then
362 Typ := Full_View (Typ);
363 end if;
364
365 if Is_Concurrent_Type (Typ)
366 and then
367 Present (Corresponding_Record_Type (Typ))
368 then
369 Typ := Corresponding_Record_Type (Typ);
370
371 -- The concurrent record's list of primitives should contain a
372 -- wrapper for the entity of the call, retrieve it.
373
374 declare
375 Prim : Entity_Id;
376 Prim_Elmt : Elmt_Id;
377 Wrapper_Found : Boolean := False;
378
379 begin
380 Prim_Elmt := First_Elmt (Primitive_Operations (Typ));
381 while Present (Prim_Elmt) loop
382 Prim := Node (Prim_Elmt);
383
384 if Is_Primitive_Wrapper (Prim)
385 and then Wrapped_Entity (Prim) = Subp_Entity
386 then
387 Wrapper_Found := True;
388 exit;
389 end if;
390
391 Next_Elmt (Prim_Elmt);
392 end loop;
393
394 -- A primitive declared between two views should have a
395 -- corresponding wrapper.
396
397 pragma Assert (Wrapper_Found);
398
399 -- Modify the call by setting the proper entity
400
401 Set_Entity (Name (N), Prim);
402 end;
403 end if;
404 end Check_Direct_Call;
405
406 -------------------------------
407 -- Check_Dispatching_Context --
408 -------------------------------
409
410 procedure Check_Dispatching_Context is
411 Subp : constant Entity_Id := Entity (Name (N));
412 Par : Node_Id;
413
414 begin
415 if Is_Abstract_Subprogram (Subp)
416 and then No (Controlling_Argument (N))
417 then
418 if Present (Alias (Subp))
419 and then not Is_Abstract_Subprogram (Alias (Subp))
420 and then No (DTC_Entity (Subp))
421 then
422 -- Private overriding of inherited abstract operation, call is
423 -- legal.
424
425 Set_Entity (Name (N), Alias (Subp));
426 return;
427
428 else
429 Par := Parent (N);
430 while Present (Par) loop
431 if Nkind_In (Par, N_Function_Call,
432 N_Procedure_Call_Statement,
433 N_Assignment_Statement,
434 N_Op_Eq,
435 N_Op_Ne)
436 and then Is_Tagged_Type (Etype (Subp))
437 then
438 return;
439
440 elsif Nkind (Par) = N_Qualified_Expression
441 or else Nkind (Par) = N_Unchecked_Type_Conversion
442 then
443 Par := Parent (Par);
444
445 else
446 if Ekind (Subp) = E_Function then
447 Error_Msg_N
448 ("call to abstract function must be dispatching", N);
449
450 -- This error can occur for a procedure in the case of a
451 -- call to an abstract formal procedure with a statically
452 -- tagged operand.
453
454 else
455 Error_Msg_N
456 ("call to abstract procedure must be dispatching",
457 N);
458 end if;
459
460 return;
461 end if;
462 end loop;
463 end if;
464 end if;
465 end Check_Dispatching_Context;
466
467 -- Start of processing for Check_Dispatching_Call
468
469 begin
470 -- Find a controlling argument, if any
471
472 if Present (Parameter_Associations (N)) then
473 Subp_Entity := Entity (Name (N));
474
475 Actual := First_Actual (N);
476 Formal := First_Formal (Subp_Entity);
477 while Present (Actual) loop
478 Control := Find_Controlling_Arg (Actual);
479 exit when Present (Control);
480
481 -- Check for the case where the actual is a tag-indeterminate call
482 -- whose result type is different than the tagged type associated
483 -- with the containing call, but is an ancestor of the type.
484
485 if Is_Controlling_Formal (Formal)
486 and then Is_Tag_Indeterminate (Actual)
487 and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal))
488 and then Is_Ancestor (Etype (Actual), Etype (Formal))
489 then
490 Indeterm_Ancestor_Call := True;
491 Indeterm_Ctrl_Type := Etype (Formal);
492
493 -- If the formal is controlling but the actual is not, the type
494 -- of the actual is statically known, and may be used as the
495 -- controlling tag for some other tag-indeterminate actual.
496
497 elsif Is_Controlling_Formal (Formal)
498 and then Is_Entity_Name (Actual)
499 and then Is_Tagged_Type (Etype (Actual))
500 then
501 Static_Tag := Actual;
502 end if;
503
504 Next_Actual (Actual);
505 Next_Formal (Formal);
506 end loop;
507
508 -- If the call doesn't have a controlling actual but does have an
509 -- indeterminate actual that requires dispatching treatment, then an
510 -- object is needed that will serve as the controlling argument for a
511 -- dispatching call on the indeterminate actual. This can only occur
512 -- in the unusual situation of a default actual given by a
513 -- tag-indeterminate call and where the type of the call is an
514 -- ancestor of the type associated with a containing call to an
515 -- inherited operation (see AI-239).
516
517 -- Rather than create an object of the tagged type, which would be
518 -- problematic for various reasons (default initialization,
519 -- discriminants), the tag of the containing call's associated tagged
520 -- type is directly used to control the dispatching.
521
522 if No (Control)
523 and then Indeterm_Ancestor_Call
524 and then No (Static_Tag)
525 then
526 Control :=
527 Make_Attribute_Reference (Loc,
528 Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc),
529 Attribute_Name => Name_Tag);
530
531 Analyze (Control);
532 end if;
533
534 if Present (Control) then
535
536 -- Verify that no controlling arguments are statically tagged
537
538 if Debug_Flag_E then
539 Write_Str ("Found Dispatching call");
540 Write_Int (Int (N));
541 Write_Eol;
542 end if;
543
544 Actual := First_Actual (N);
545 while Present (Actual) loop
546 if Actual /= Control then
547
548 if not Is_Controlling_Actual (Actual) then
549 null; -- Can be anything
550
551 elsif Is_Dynamically_Tagged (Actual) then
552 null; -- Valid parameter
553
554 elsif Is_Tag_Indeterminate (Actual) then
555
556 -- The tag is inherited from the enclosing call (the node
557 -- we are currently analyzing). Explicitly expand the
558 -- actual, since the previous call to Expand (from
559 -- Resolve_Call) had no way of knowing about the required
560 -- dispatching.
561
562 Propagate_Tag (Control, Actual);
563
564 else
565 Error_Msg_N
566 ("controlling argument is not dynamically tagged",
567 Actual);
568 return;
569 end if;
570 end if;
571
572 Next_Actual (Actual);
573 end loop;
574
575 -- Mark call as a dispatching call
576
577 Set_Controlling_Argument (N, Control);
578 Check_Restriction (No_Dispatching_Calls, N);
579
580 -- The dispatching call may need to be converted into a direct
581 -- call in certain cases.
582
583 Check_Direct_Call;
584
585 -- If there is a statically tagged actual and a tag-indeterminate
586 -- call to a function of the ancestor (such as that provided by a
587 -- default), then treat this as a dispatching call and propagate
588 -- the tag to the tag-indeterminate call(s).
589
590 elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then
591 Control :=
592 Make_Attribute_Reference (Loc,
593 Prefix =>
594 New_Occurrence_Of (Etype (Static_Tag), Loc),
595 Attribute_Name => Name_Tag);
596
597 Analyze (Control);
598
599 Actual := First_Actual (N);
600 Formal := First_Formal (Subp_Entity);
601 while Present (Actual) loop
602 if Is_Tag_Indeterminate (Actual)
603 and then Is_Controlling_Formal (Formal)
604 then
605 Propagate_Tag (Control, Actual);
606 end if;
607
608 Next_Actual (Actual);
609 Next_Formal (Formal);
610 end loop;
611
612 Check_Dispatching_Context;
613
614 else
615 -- The call is not dispatching, so check that there aren't any
616 -- tag-indeterminate abstract calls left.
617
618 Actual := First_Actual (N);
619 while Present (Actual) loop
620 if Is_Tag_Indeterminate (Actual) then
621
622 -- Function call case
623
624 if Nkind (Original_Node (Actual)) = N_Function_Call then
625 Func := Entity (Name (Original_Node (Actual)));
626
627 -- If the actual is an attribute then it can't be abstract
628 -- (the only current case of a tag-indeterminate attribute
629 -- is the stream Input attribute).
630
631 elsif
632 Nkind (Original_Node (Actual)) = N_Attribute_Reference
633 then
634 Func := Empty;
635
636 -- Only other possibility is a qualified expression whose
637 -- constituent expression is itself a call.
638
639 else
640 Func :=
641 Entity (Name
642 (Original_Node
643 (Expression (Original_Node (Actual)))));
644 end if;
645
646 if Present (Func) and then Is_Abstract_Subprogram (Func) then
647 Error_Msg_N (
648 "call to abstract function must be dispatching", N);
649 end if;
650 end if;
651
652 Next_Actual (Actual);
653 end loop;
654
655 Check_Dispatching_Context;
656 end if;
657
658 else
659 -- If dispatching on result, the enclosing call, if any, will
660 -- determine the controlling argument. Otherwise this is the
661 -- primitive operation of the root type.
662
663 Check_Dispatching_Context;
664 end if;
665 end Check_Dispatching_Call;
666
667 ---------------------------------
668 -- Check_Dispatching_Operation --
669 ---------------------------------
670
671 procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id) is
672 Tagged_Type : Entity_Id;
673 Has_Dispatching_Parent : Boolean := False;
674 Body_Is_Last_Primitive : Boolean := False;
675
676 function Is_Visibly_Controlled (T : Entity_Id) return Boolean;
677 -- Check whether T is derived from a visibly controlled type.
678 -- This is true if the root type is declared in Ada.Finalization.
679 -- If T is derived instead from a private type whose full view
680 -- is controlled, an explicit Initialize/Adjust/Finalize subprogram
681 -- does not override the inherited one.
682
683 ---------------------------
684 -- Is_Visibly_Controlled --
685 ---------------------------
686
687 function Is_Visibly_Controlled (T : Entity_Id) return Boolean is
688 Root : constant Entity_Id := Root_Type (T);
689 begin
690 return Chars (Scope (Root)) = Name_Finalization
691 and then Chars (Scope (Scope (Root))) = Name_Ada
692 and then Scope (Scope (Scope (Root))) = Standard_Standard;
693 end Is_Visibly_Controlled;
694
695 -- Start of processing for Check_Dispatching_Operation
696
697 begin
698 if Ekind (Subp) /= E_Procedure and then Ekind (Subp) /= E_Function then
699 return;
700 end if;
701
702 Set_Is_Dispatching_Operation (Subp, False);
703 Tagged_Type := Find_Dispatching_Type (Subp);
704
705 -- Ada 2005 (AI-345)
706
707 if Ada_Version = Ada_05
708 and then Present (Tagged_Type)
709 and then Is_Concurrent_Type (Tagged_Type)
710 then
711 -- Protect the frontend against previously detected errors
712
713 if No (Corresponding_Record_Type (Tagged_Type)) then
714 return;
715 end if;
716
717 Tagged_Type := Corresponding_Record_Type (Tagged_Type);
718 end if;
719
720 -- (AI-345): The task body procedure is not a primitive of the tagged
721 -- type
722
723 if Present (Tagged_Type)
724 and then Is_Concurrent_Record_Type (Tagged_Type)
725 and then Present (Corresponding_Concurrent_Type (Tagged_Type))
726 and then Is_Task_Type (Corresponding_Concurrent_Type (Tagged_Type))
727 and then Subp = Get_Task_Body_Procedure
728 (Corresponding_Concurrent_Type (Tagged_Type))
729 then
730 return;
731 end if;
732
733 -- If Subp is derived from a dispatching operation then it should
734 -- always be treated as dispatching. In this case various checks
735 -- below will be bypassed. Makes sure that late declarations for
736 -- inherited private subprograms are treated as dispatching, even
737 -- if the associated tagged type is already frozen.
738
739 Has_Dispatching_Parent :=
740 Present (Alias (Subp))
741 and then Is_Dispatching_Operation (Alias (Subp));
742
743 if No (Tagged_Type) then
744
745 -- Ada 2005 (AI-251): Check that Subp is not a primitive associated
746 -- with an abstract interface type unless the interface acts as a
747 -- parent type in a derivation. If the interface type is a formal
748 -- type then the operation is not primitive and therefore legal.
749
750 declare
751 E : Entity_Id;
752 Typ : Entity_Id;
753
754 begin
755 E := First_Entity (Subp);
756 while Present (E) loop
757
758 -- For an access parameter, check designated type
759
760 if Ekind (Etype (E)) = E_Anonymous_Access_Type then
761 Typ := Designated_Type (Etype (E));
762 else
763 Typ := Etype (E);
764 end if;
765
766 if Comes_From_Source (Subp)
767 and then Is_Interface (Typ)
768 and then not Is_Class_Wide_Type (Typ)
769 and then not Is_Derived_Type (Typ)
770 and then not Is_Generic_Type (Typ)
771 and then not In_Instance
772 then
773 Error_Msg_N ("?declaration of& is too late!", Subp);
774 Error_Msg_NE
775 ("\spec should appear immediately after declaration of &!",
776 Subp, Typ);
777 exit;
778 end if;
779
780 Next_Entity (E);
781 end loop;
782
783 -- In case of functions check also the result type
784
785 if Ekind (Subp) = E_Function then
786 if Is_Access_Type (Etype (Subp)) then
787 Typ := Designated_Type (Etype (Subp));
788 else
789 Typ := Etype (Subp);
790 end if;
791
792 if not Is_Class_Wide_Type (Typ)
793 and then Is_Interface (Typ)
794 and then not Is_Derived_Type (Typ)
795 then
796 Error_Msg_N ("?declaration of& is too late!", Subp);
797 Error_Msg_NE
798 ("\spec should appear immediately after declaration of &!",
799 Subp, Typ);
800 end if;
801 end if;
802 end;
803
804 return;
805
806 -- The subprograms build internally after the freezing point (such as
807 -- init procs, interface thunks, type support subprograms, and Offset
808 -- to top functions for accessing interface components in variable
809 -- size tagged types) are not primitives.
810
811 elsif Is_Frozen (Tagged_Type)
812 and then not Comes_From_Source (Subp)
813 and then not Has_Dispatching_Parent
814 then
815 -- Complete decoration if internally built subprograms that override
816 -- a dispatching primitive. These entities correspond with the
817 -- following cases:
818
819 -- 1. Ada 2005 (AI-391): Wrapper functions built by the expander
820 -- to override functions of nonabstract null extensions. These
821 -- primitives were added to the list of primitives of the tagged
822 -- type by Make_Controlling_Function_Wrappers. However, attribute
823 -- Is_Dispatching_Operation must be set to true.
824
825 -- 2. Subprograms associated with stream attributes (built by
826 -- New_Stream_Subprogram)
827
828 if Present (Old_Subp)
829 and then Is_Overriding_Operation (Subp)
830 and then Is_Dispatching_Operation (Old_Subp)
831 then
832 pragma Assert
833 ((Ekind (Subp) = E_Function
834 and then Is_Dispatching_Operation (Old_Subp)
835 and then Is_Null_Extension (Base_Type (Etype (Subp))))
836 or else Get_TSS_Name (Subp) = TSS_Stream_Read
837 or else Get_TSS_Name (Subp) = TSS_Stream_Write);
838
839 Set_Is_Dispatching_Operation (Subp);
840 end if;
841
842 return;
843
844 -- The operation may be a child unit, whose scope is the defining
845 -- package, but which is not a primitive operation of the type.
846
847 elsif Is_Child_Unit (Subp) then
848 return;
849
850 -- If the subprogram is not defined in a package spec, the only case
851 -- where it can be a dispatching op is when it overrides an operation
852 -- before the freezing point of the type.
853
854 elsif ((not Is_Package_Or_Generic_Package (Scope (Subp)))
855 or else In_Package_Body (Scope (Subp)))
856 and then not Has_Dispatching_Parent
857 then
858 if not Comes_From_Source (Subp)
859 or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type))
860 then
861 null;
862
863 -- If the type is already frozen, the overriding is not allowed
864 -- except when Old_Subp is not a dispatching operation (which can
865 -- occur when Old_Subp was inherited by an untagged type). However,
866 -- a body with no previous spec freezes the type *after* its
867 -- declaration, and therefore is a legal overriding (unless the type
868 -- has already been frozen). Only the first such body is legal.
869
870 elsif Present (Old_Subp)
871 and then Is_Dispatching_Operation (Old_Subp)
872 then
873 if Comes_From_Source (Subp)
874 and then
875 (Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body
876 or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub)
877 then
878 declare
879 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
880 Decl_Item : Node_Id;
881
882 begin
883 -- ??? The checks here for whether the type has been
884 -- frozen prior to the new body are not complete. It's
885 -- not simple to check frozenness at this point since
886 -- the body has already caused the type to be prematurely
887 -- frozen in Analyze_Declarations, but we're forced to
888 -- recheck this here because of the odd rule interpretation
889 -- that allows the overriding if the type wasn't frozen
890 -- prior to the body. The freezing action should probably
891 -- be delayed until after the spec is seen, but that's
892 -- a tricky change to the delicate freezing code.
893
894 -- Look at each declaration following the type up until the
895 -- new subprogram body. If any of the declarations is a body
896 -- then the type has been frozen already so the overriding
897 -- primitive is illegal.
898
899 Decl_Item := Next (Parent (Tagged_Type));
900 while Present (Decl_Item)
901 and then (Decl_Item /= Subp_Body)
902 loop
903 if Comes_From_Source (Decl_Item)
904 and then (Nkind (Decl_Item) in N_Proper_Body
905 or else Nkind (Decl_Item) in N_Body_Stub)
906 then
907 Error_Msg_N ("overriding of& is too late!", Subp);
908 Error_Msg_N
909 ("\spec should appear immediately after the type!",
910 Subp);
911 exit;
912 end if;
913
914 Next (Decl_Item);
915 end loop;
916
917 -- If the subprogram doesn't follow in the list of
918 -- declarations including the type then the type has
919 -- definitely been frozen already and the body is illegal.
920
921 if No (Decl_Item) then
922 Error_Msg_N ("overriding of& is too late!", Subp);
923 Error_Msg_N
924 ("\spec should appear immediately after the type!",
925 Subp);
926
927 elsif Is_Frozen (Subp) then
928
929 -- The subprogram body declares a primitive operation.
930 -- if the subprogram is already frozen, we must update
931 -- its dispatching information explicitly here. The
932 -- information is taken from the overridden subprogram.
933 -- We must also generate a cross-reference entry because
934 -- references to other primitives were already created
935 -- when type was frozen.
936
937 Body_Is_Last_Primitive := True;
938
939 if Present (DTC_Entity (Old_Subp)) then
940 Set_DTC_Entity (Subp, DTC_Entity (Old_Subp));
941 Set_DT_Position (Subp, DT_Position (Old_Subp));
942
943 if not Restriction_Active (No_Dispatching_Calls) then
944 if Building_Static_DT (Tagged_Type) then
945
946 -- If the static dispatch table has not been
947 -- built then there is nothing else to do now;
948 -- otherwise we notify that we cannot build the
949 -- static dispatch table.
950
951 if Has_Dispatch_Table (Tagged_Type) then
952 Error_Msg_N
953 ("overriding of& is too late for building" &
954 " static dispatch tables!", Subp);
955 Error_Msg_N
956 ("\spec should appear immediately after" &
957 " the type!", Subp);
958 end if;
959
960 else
961 Insert_Actions_After (Subp_Body,
962 Register_Primitive (Sloc (Subp_Body),
963 Prim => Subp));
964 end if;
965
966 -- Indicate that this is an overriding operation,
967 -- and replace the overriden entry in the list of
968 -- primitive operations, which is used for xref
969 -- generation subsequently.
970
971 Generate_Reference (Tagged_Type, Subp, 'P', False);
972 Override_Dispatching_Operation
973 (Tagged_Type, Old_Subp, Subp);
974 end if;
975 end if;
976 end if;
977 end;
978
979 else
980 Error_Msg_N ("overriding of& is too late!", Subp);
981 Error_Msg_N
982 ("\subprogram spec should appear immediately after the type!",
983 Subp);
984 end if;
985
986 -- If the type is not frozen yet and we are not in the overriding
987 -- case it looks suspiciously like an attempt to define a primitive
988 -- operation, which requires the declaration to be in a package spec
989 -- (3.2.3(6)).
990
991 elsif not Is_Frozen (Tagged_Type) then
992 Error_Msg_N
993 ("?not dispatching (must be defined in a package spec)", Subp);
994 return;
995
996 -- When the type is frozen, it is legitimate to define a new
997 -- non-primitive operation.
998
999 else
1000 return;
1001 end if;
1002
1003 -- Now, we are sure that the scope is a package spec. If the subprogram
1004 -- is declared after the freezing point of the type that's an error
1005
1006 elsif Is_Frozen (Tagged_Type) and then not Has_Dispatching_Parent then
1007 Error_Msg_N ("this primitive operation is declared too late", Subp);
1008 Error_Msg_NE
1009 ("?no primitive operations for& after this line",
1010 Freeze_Node (Tagged_Type),
1011 Tagged_Type);
1012 return;
1013 end if;
1014
1015 Check_Controlling_Formals (Tagged_Type, Subp);
1016
1017 -- Now it should be a correct primitive operation, put it in the list
1018
1019 if Present (Old_Subp) then
1020
1021 -- If the type has interfaces we complete this check after we set
1022 -- attribute Is_Dispatching_Operation.
1023
1024 Check_Subtype_Conformant (Subp, Old_Subp);
1025
1026 if (Chars (Subp) = Name_Initialize
1027 or else Chars (Subp) = Name_Adjust
1028 or else Chars (Subp) = Name_Finalize)
1029 and then Is_Controlled (Tagged_Type)
1030 and then not Is_Visibly_Controlled (Tagged_Type)
1031 then
1032 Set_Is_Overriding_Operation (Subp, False);
1033 Error_Msg_NE
1034 ("operation does not override inherited&?", Subp, Subp);
1035 else
1036 Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp);
1037 Set_Is_Overriding_Operation (Subp);
1038
1039 -- Ada 2005 (AI-251): In case of late overriding of a primitive
1040 -- that covers abstract interface subprograms we must register it
1041 -- in all the secondary dispatch tables associated with abstract
1042 -- interfaces. We do this now only if not building static tables.
1043 -- Otherwise the patch code is emitted after those tables are
1044 -- built, to prevent access_before_elaboration in gigi.
1045
1046 if Body_Is_Last_Primitive then
1047 declare
1048 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp);
1049 Elmt : Elmt_Id;
1050 Prim : Node_Id;
1051
1052 begin
1053 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1054 while Present (Elmt) loop
1055 Prim := Node (Elmt);
1056
1057 if Present (Alias (Prim))
1058 and then Present (Interface_Alias (Prim))
1059 and then Alias (Prim) = Subp
1060 and then not Building_Static_DT (Tagged_Type)
1061 then
1062 Insert_Actions_After (Subp_Body,
1063 Register_Primitive (Sloc (Subp_Body), Prim => Prim));
1064 end if;
1065
1066 Next_Elmt (Elmt);
1067 end loop;
1068
1069 -- Redisplay the contents of the updated dispatch table
1070
1071 if Debug_Flag_ZZ then
1072 Write_Str ("Late overriding: ");
1073 Write_DT (Tagged_Type);
1074 end if;
1075 end;
1076 end if;
1077 end if;
1078
1079 -- If no old subprogram, then we add this as a dispatching operation,
1080 -- but we avoid doing this if an error was posted, to prevent annoying
1081 -- cascaded errors.
1082
1083 elsif not Error_Posted (Subp) then
1084 Add_Dispatching_Operation (Tagged_Type, Subp);
1085 end if;
1086
1087 Set_Is_Dispatching_Operation (Subp, True);
1088
1089 -- Ada 2005 (AI-251): If the type implements interfaces we must check
1090 -- subtype conformance against all the interfaces covered by this
1091 -- primitive.
1092
1093 if Present (Old_Subp)
1094 and then Has_Interfaces (Tagged_Type)
1095 then
1096 declare
1097 Ifaces_List : Elist_Id;
1098 Iface_Elmt : Elmt_Id;
1099 Iface_Prim_Elmt : Elmt_Id;
1100 Iface_Prim : Entity_Id;
1101 Ret_Typ : Entity_Id;
1102
1103 begin
1104 Collect_Interfaces (Tagged_Type, Ifaces_List);
1105
1106 Iface_Elmt := First_Elmt (Ifaces_List);
1107 while Present (Iface_Elmt) loop
1108 if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then
1109 Iface_Prim_Elmt :=
1110 First_Elmt (Primitive_Operations (Node (Iface_Elmt)));
1111 while Present (Iface_Prim_Elmt) loop
1112 Iface_Prim := Node (Iface_Prim_Elmt);
1113
1114 if Is_Interface_Conformant
1115 (Tagged_Type, Iface_Prim, Subp)
1116 then
1117 -- Handle procedures, functions whose return type
1118 -- matches, or functions not returning interfaces
1119
1120 if Ekind (Subp) = E_Procedure
1121 or else Etype (Iface_Prim) = Etype (Subp)
1122 or else not Is_Interface (Etype (Iface_Prim))
1123 then
1124 Check_Subtype_Conformant
1125 (New_Id => Subp,
1126 Old_Id => Iface_Prim,
1127 Err_Loc => Subp,
1128 Skip_Controlling_Formals => True);
1129
1130 -- Handle functions returning interfaces
1131
1132 elsif Implements_Interface
1133 (Etype (Subp), Etype (Iface_Prim))
1134 then
1135 -- Temporarily force both entities to return the
1136 -- same type. Required because Subtype_Conformant
1137 -- does not handle this case.
1138
1139 Ret_Typ := Etype (Iface_Prim);
1140 Set_Etype (Iface_Prim, Etype (Subp));
1141
1142 Check_Subtype_Conformant
1143 (New_Id => Subp,
1144 Old_Id => Iface_Prim,
1145 Err_Loc => Subp,
1146 Skip_Controlling_Formals => True);
1147
1148 Set_Etype (Iface_Prim, Ret_Typ);
1149 end if;
1150 end if;
1151
1152 Next_Elmt (Iface_Prim_Elmt);
1153 end loop;
1154 end if;
1155
1156 Next_Elmt (Iface_Elmt);
1157 end loop;
1158 end;
1159 end if;
1160
1161 if not Body_Is_Last_Primitive then
1162 Set_DT_Position (Subp, No_Uint);
1163
1164 elsif Has_Controlled_Component (Tagged_Type)
1165 and then
1166 (Chars (Subp) = Name_Initialize
1167 or else
1168 Chars (Subp) = Name_Adjust
1169 or else
1170 Chars (Subp) = Name_Finalize)
1171 then
1172 declare
1173 F_Node : constant Node_Id := Freeze_Node (Tagged_Type);
1174 Decl : Node_Id;
1175 Old_P : Entity_Id;
1176 Old_Bod : Node_Id;
1177 Old_Spec : Entity_Id;
1178
1179 C_Names : constant array (1 .. 3) of Name_Id :=
1180 (Name_Initialize,
1181 Name_Adjust,
1182 Name_Finalize);
1183
1184 D_Names : constant array (1 .. 3) of TSS_Name_Type :=
1185 (TSS_Deep_Initialize,
1186 TSS_Deep_Adjust,
1187 TSS_Deep_Finalize);
1188
1189 begin
1190 -- Remove previous controlled function which was constructed and
1191 -- analyzed when the type was frozen. This requires removing the
1192 -- body of the redefined primitive, as well as its specification
1193 -- if needed (there is no spec created for Deep_Initialize, see
1194 -- exp_ch3.adb). We must also dismantle the exception information
1195 -- that may have been generated for it when front end zero-cost
1196 -- tables are enabled.
1197
1198 for J in D_Names'Range loop
1199 Old_P := TSS (Tagged_Type, D_Names (J));
1200
1201 if Present (Old_P)
1202 and then Chars (Subp) = C_Names (J)
1203 then
1204 Old_Bod := Unit_Declaration_Node (Old_P);
1205 Remove (Old_Bod);
1206 Set_Is_Eliminated (Old_P);
1207 Set_Scope (Old_P, Scope (Current_Scope));
1208
1209 if Nkind (Old_Bod) = N_Subprogram_Body
1210 and then Present (Corresponding_Spec (Old_Bod))
1211 then
1212 Old_Spec := Corresponding_Spec (Old_Bod);
1213 Set_Has_Completion (Old_Spec, False);
1214 end if;
1215 end if;
1216 end loop;
1217
1218 Build_Late_Proc (Tagged_Type, Chars (Subp));
1219
1220 -- The new operation is added to the actions of the freeze node
1221 -- for the type, but this node has already been analyzed, so we
1222 -- must retrieve and analyze explicitly the new body.
1223
1224 if Present (F_Node)
1225 and then Present (Actions (F_Node))
1226 then
1227 Decl := Last (Actions (F_Node));
1228 Analyze (Decl);
1229 end if;
1230 end;
1231 end if;
1232 end Check_Dispatching_Operation;
1233
1234 ------------------------------------------
1235 -- Check_Operation_From_Incomplete_Type --
1236 ------------------------------------------
1237
1238 procedure Check_Operation_From_Incomplete_Type
1239 (Subp : Entity_Id;
1240 Typ : Entity_Id)
1241 is
1242 Full : constant Entity_Id := Full_View (Typ);
1243 Parent_Typ : constant Entity_Id := Etype (Full);
1244 Old_Prim : constant Elist_Id := Primitive_Operations (Parent_Typ);
1245 New_Prim : constant Elist_Id := Primitive_Operations (Full);
1246 Op1, Op2 : Elmt_Id;
1247 Prev : Elmt_Id := No_Elmt;
1248
1249 function Derives_From (Proc : Entity_Id) return Boolean;
1250 -- Check that Subp has the signature of an operation derived from Proc.
1251 -- Subp has an access parameter that designates Typ.
1252
1253 ------------------
1254 -- Derives_From --
1255 ------------------
1256
1257 function Derives_From (Proc : Entity_Id) return Boolean is
1258 F1, F2 : Entity_Id;
1259
1260 begin
1261 if Chars (Proc) /= Chars (Subp) then
1262 return False;
1263 end if;
1264
1265 F1 := First_Formal (Proc);
1266 F2 := First_Formal (Subp);
1267 while Present (F1) and then Present (F2) loop
1268 if Ekind (Etype (F1)) = E_Anonymous_Access_Type then
1269 if Ekind (Etype (F2)) /= E_Anonymous_Access_Type then
1270 return False;
1271 elsif Designated_Type (Etype (F1)) = Parent_Typ
1272 and then Designated_Type (Etype (F2)) /= Full
1273 then
1274 return False;
1275 end if;
1276
1277 elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then
1278 return False;
1279
1280 elsif Etype (F1) /= Etype (F2) then
1281 return False;
1282 end if;
1283
1284 Next_Formal (F1);
1285 Next_Formal (F2);
1286 end loop;
1287
1288 return No (F1) and then No (F2);
1289 end Derives_From;
1290
1291 -- Start of processing for Check_Operation_From_Incomplete_Type
1292
1293 begin
1294 -- The operation may override an inherited one, or may be a new one
1295 -- altogether. The inherited operation will have been hidden by the
1296 -- current one at the point of the type derivation, so it does not
1297 -- appear in the list of primitive operations of the type. We have to
1298 -- find the proper place of insertion in the list of primitive opera-
1299 -- tions by iterating over the list for the parent type.
1300
1301 Op1 := First_Elmt (Old_Prim);
1302 Op2 := First_Elmt (New_Prim);
1303 while Present (Op1) and then Present (Op2) loop
1304 if Derives_From (Node (Op1)) then
1305 if No (Prev) then
1306
1307 -- Avoid adding it to the list of primitives if already there!
1308
1309 if Node (Op2) /= Subp then
1310 Prepend_Elmt (Subp, New_Prim);
1311 end if;
1312
1313 else
1314 Insert_Elmt_After (Subp, Prev);
1315 end if;
1316
1317 return;
1318 end if;
1319
1320 Prev := Op2;
1321 Next_Elmt (Op1);
1322 Next_Elmt (Op2);
1323 end loop;
1324
1325 -- Operation is a new primitive
1326
1327 Append_Elmt (Subp, New_Prim);
1328 end Check_Operation_From_Incomplete_Type;
1329
1330 ---------------------------------------
1331 -- Check_Operation_From_Private_View --
1332 ---------------------------------------
1333
1334 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is
1335 Tagged_Type : Entity_Id;
1336
1337 begin
1338 if Is_Dispatching_Operation (Alias (Subp)) then
1339 Set_Scope (Subp, Current_Scope);
1340 Tagged_Type := Find_Dispatching_Type (Subp);
1341
1342 -- Add Old_Subp to primitive operations if not already present
1343
1344 if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then
1345 Append_Unique_Elmt (Old_Subp, Primitive_Operations (Tagged_Type));
1346
1347 -- If Old_Subp isn't already marked as dispatching then
1348 -- this is the case of an operation of an untagged private
1349 -- type fulfilled by a tagged type that overrides an
1350 -- inherited dispatching operation, so we set the necessary
1351 -- dispatching attributes here.
1352
1353 if not Is_Dispatching_Operation (Old_Subp) then
1354
1355 -- If the untagged type has no discriminants, and the full
1356 -- view is constrained, there will be a spurious mismatch
1357 -- of subtypes on the controlling arguments, because the tagged
1358 -- type is the internal base type introduced in the derivation.
1359 -- Use the original type to verify conformance, rather than the
1360 -- base type.
1361
1362 if not Comes_From_Source (Tagged_Type)
1363 and then Has_Discriminants (Tagged_Type)
1364 then
1365 declare
1366 Formal : Entity_Id;
1367
1368 begin
1369 Formal := First_Formal (Old_Subp);
1370 while Present (Formal) loop
1371 if Tagged_Type = Base_Type (Etype (Formal)) then
1372 Tagged_Type := Etype (Formal);
1373 end if;
1374
1375 Next_Formal (Formal);
1376 end loop;
1377 end;
1378
1379 if Tagged_Type = Base_Type (Etype (Old_Subp)) then
1380 Tagged_Type := Etype (Old_Subp);
1381 end if;
1382 end if;
1383
1384 Check_Controlling_Formals (Tagged_Type, Old_Subp);
1385 Set_Is_Dispatching_Operation (Old_Subp, True);
1386 Set_DT_Position (Old_Subp, No_Uint);
1387 end if;
1388
1389 -- If the old subprogram is an explicit renaming of some other
1390 -- entity, it is not overridden by the inherited subprogram.
1391 -- Otherwise, update its alias and other attributes.
1392
1393 if Present (Alias (Old_Subp))
1394 and then Nkind (Unit_Declaration_Node (Old_Subp)) /=
1395 N_Subprogram_Renaming_Declaration
1396 then
1397 Set_Alias (Old_Subp, Alias (Subp));
1398
1399 -- The derived subprogram should inherit the abstractness
1400 -- of the parent subprogram (except in the case of a function
1401 -- returning the type). This sets the abstractness properly
1402 -- for cases where a private extension may have inherited
1403 -- an abstract operation, but the full type is derived from
1404 -- a descendant type and inherits a nonabstract version.
1405
1406 if Etype (Subp) /= Tagged_Type then
1407 Set_Is_Abstract_Subprogram
1408 (Old_Subp, Is_Abstract_Subprogram (Alias (Subp)));
1409 end if;
1410 end if;
1411 end if;
1412 end if;
1413 end Check_Operation_From_Private_View;
1414
1415 --------------------------
1416 -- Find_Controlling_Arg --
1417 --------------------------
1418
1419 function Find_Controlling_Arg (N : Node_Id) return Node_Id is
1420 Orig_Node : constant Node_Id := Original_Node (N);
1421 Typ : Entity_Id;
1422
1423 begin
1424 if Nkind (Orig_Node) = N_Qualified_Expression then
1425 return Find_Controlling_Arg (Expression (Orig_Node));
1426 end if;
1427
1428 -- Dispatching on result case. If expansion is disabled, the node still
1429 -- has the structure of a function call. However, if the function name
1430 -- is an operator and the call was given in infix form, the original
1431 -- node has no controlling result and we must examine the current node.
1432
1433 if Nkind (N) = N_Function_Call
1434 and then Present (Controlling_Argument (N))
1435 and then Has_Controlling_Result (Entity (Name (N)))
1436 then
1437 return Controlling_Argument (N);
1438
1439 -- If expansion is enabled, the call may have been transformed into
1440 -- an indirect call, and we need to recover the original node.
1441
1442 elsif Nkind (Orig_Node) = N_Function_Call
1443 and then Present (Controlling_Argument (Orig_Node))
1444 and then Has_Controlling_Result (Entity (Name (Orig_Node)))
1445 then
1446 return Controlling_Argument (Orig_Node);
1447
1448 -- Normal case
1449
1450 elsif Is_Controlling_Actual (N)
1451 or else
1452 (Nkind (Parent (N)) = N_Qualified_Expression
1453 and then Is_Controlling_Actual (Parent (N)))
1454 then
1455 Typ := Etype (N);
1456
1457 if Is_Access_Type (Typ) then
1458
1459 -- In the case of an Access attribute, use the type of the prefix,
1460 -- since in the case of an actual for an access parameter, the
1461 -- attribute's type may be of a specific designated type, even
1462 -- though the prefix type is class-wide.
1463
1464 if Nkind (N) = N_Attribute_Reference then
1465 Typ := Etype (Prefix (N));
1466
1467 -- An allocator is dispatching if the type of qualified expression
1468 -- is class_wide, in which case this is the controlling type.
1469
1470 elsif Nkind (Orig_Node) = N_Allocator
1471 and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression
1472 then
1473 Typ := Etype (Expression (Orig_Node));
1474 else
1475 Typ := Designated_Type (Typ);
1476 end if;
1477 end if;
1478
1479 if Is_Class_Wide_Type (Typ)
1480 or else
1481 (Nkind (Parent (N)) = N_Qualified_Expression
1482 and then Is_Access_Type (Etype (N))
1483 and then Is_Class_Wide_Type (Designated_Type (Etype (N))))
1484 then
1485 return N;
1486 end if;
1487 end if;
1488
1489 return Empty;
1490 end Find_Controlling_Arg;
1491
1492 ---------------------------
1493 -- Find_Dispatching_Type --
1494 ---------------------------
1495
1496 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is
1497 A_Formal : Entity_Id;
1498 Formal : Entity_Id;
1499 Ctrl_Type : Entity_Id;
1500
1501 begin
1502 if Present (DTC_Entity (Subp)) then
1503 return Scope (DTC_Entity (Subp));
1504
1505 -- For subprograms internally generated by derivations of tagged types
1506 -- use the alias subprogram as a reference to locate the dispatching
1507 -- type of Subp
1508
1509 elsif not Comes_From_Source (Subp)
1510 and then Present (Alias (Subp))
1511 and then Is_Dispatching_Operation (Alias (Subp))
1512 then
1513 if Ekind (Alias (Subp)) = E_Function
1514 and then Has_Controlling_Result (Alias (Subp))
1515 then
1516 return Check_Controlling_Type (Etype (Subp), Subp);
1517
1518 else
1519 Formal := First_Formal (Subp);
1520 A_Formal := First_Formal (Alias (Subp));
1521 while Present (A_Formal) loop
1522 if Is_Controlling_Formal (A_Formal) then
1523 return Check_Controlling_Type (Etype (Formal), Subp);
1524 end if;
1525
1526 Next_Formal (Formal);
1527 Next_Formal (A_Formal);
1528 end loop;
1529
1530 pragma Assert (False);
1531 return Empty;
1532 end if;
1533
1534 -- General case
1535
1536 else
1537 Formal := First_Formal (Subp);
1538 while Present (Formal) loop
1539 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
1540
1541 if Present (Ctrl_Type) then
1542 return Ctrl_Type;
1543 end if;
1544
1545 Next_Formal (Formal);
1546 end loop;
1547
1548 -- The subprogram may also be dispatching on result
1549
1550 if Present (Etype (Subp)) then
1551 return Check_Controlling_Type (Etype (Subp), Subp);
1552 end if;
1553 end if;
1554
1555 pragma Assert (not Is_Dispatching_Operation (Subp));
1556 return Empty;
1557 end Find_Dispatching_Type;
1558
1559 ---------------------------------------
1560 -- Find_Primitive_Covering_Interface --
1561 ---------------------------------------
1562
1563 function Find_Primitive_Covering_Interface
1564 (Tagged_Type : Entity_Id;
1565 Iface_Prim : Entity_Id) return Entity_Id
1566 is
1567 E : Entity_Id;
1568
1569 begin
1570 pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim))
1571 or else (Present (Alias (Iface_Prim))
1572 and then
1573 Is_Interface
1574 (Find_Dispatching_Type (Ultimate_Alias (Iface_Prim)))));
1575
1576 E := Current_Entity (Iface_Prim);
1577 while Present (E) loop
1578 if Is_Subprogram (E)
1579 and then Is_Dispatching_Operation (E)
1580 and then Is_Interface_Conformant (Tagged_Type, Iface_Prim, E)
1581 then
1582 return E;
1583 end if;
1584
1585 E := Homonym (E);
1586 end loop;
1587
1588 return Empty;
1589 end Find_Primitive_Covering_Interface;
1590
1591 ---------------------------
1592 -- Is_Dynamically_Tagged --
1593 ---------------------------
1594
1595 function Is_Dynamically_Tagged (N : Node_Id) return Boolean is
1596 begin
1597 if Nkind (N) = N_Error then
1598 return False;
1599 else
1600 return Find_Controlling_Arg (N) /= Empty;
1601 end if;
1602 end Is_Dynamically_Tagged;
1603
1604 --------------------------
1605 -- Is_Tag_Indeterminate --
1606 --------------------------
1607
1608 function Is_Tag_Indeterminate (N : Node_Id) return Boolean is
1609 Nam : Entity_Id;
1610 Actual : Node_Id;
1611 Orig_Node : constant Node_Id := Original_Node (N);
1612
1613 begin
1614 if Nkind (Orig_Node) = N_Function_Call
1615 and then Is_Entity_Name (Name (Orig_Node))
1616 then
1617 Nam := Entity (Name (Orig_Node));
1618
1619 if not Has_Controlling_Result (Nam) then
1620 return False;
1621
1622 -- An explicit dereference means that the call has already been
1623 -- expanded and there is no tag to propagate.
1624
1625 elsif Nkind (N) = N_Explicit_Dereference then
1626 return False;
1627
1628 -- If there are no actuals, the call is tag-indeterminate
1629
1630 elsif No (Parameter_Associations (Orig_Node)) then
1631 return True;
1632
1633 else
1634 Actual := First_Actual (Orig_Node);
1635 while Present (Actual) loop
1636 if Is_Controlling_Actual (Actual)
1637 and then not Is_Tag_Indeterminate (Actual)
1638 then
1639 return False; -- one operand is dispatching
1640 end if;
1641
1642 Next_Actual (Actual);
1643 end loop;
1644
1645 return True;
1646 end if;
1647
1648 elsif Nkind (Orig_Node) = N_Qualified_Expression then
1649 return Is_Tag_Indeterminate (Expression (Orig_Node));
1650
1651 -- Case of a call to the Input attribute (possibly rewritten), which is
1652 -- always tag-indeterminate except when its prefix is a Class attribute.
1653
1654 elsif Nkind (Orig_Node) = N_Attribute_Reference
1655 and then
1656 Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input
1657 and then
1658 Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference
1659 then
1660 return True;
1661
1662 -- In Ada 2005 a function that returns an anonymous access type can
1663 -- dispatching, and the dereference of a call to such a function
1664 -- is also tag-indeterminate.
1665
1666 elsif Nkind (Orig_Node) = N_Explicit_Dereference
1667 and then Ada_Version >= Ada_05
1668 then
1669 return Is_Tag_Indeterminate (Prefix (Orig_Node));
1670
1671 else
1672 return False;
1673 end if;
1674 end Is_Tag_Indeterminate;
1675
1676 ------------------------------------
1677 -- Override_Dispatching_Operation --
1678 ------------------------------------
1679
1680 procedure Override_Dispatching_Operation
1681 (Tagged_Type : Entity_Id;
1682 Prev_Op : Entity_Id;
1683 New_Op : Entity_Id)
1684 is
1685 Elmt : Elmt_Id;
1686 Prim : Node_Id;
1687
1688 begin
1689 -- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but
1690 -- we do it unconditionally in Ada 95 now, since this is our pragma!)
1691
1692 if No_Return (Prev_Op) and then not No_Return (New_Op) then
1693 Error_Msg_N ("procedure & must have No_Return pragma", New_Op);
1694 Error_Msg_N ("\since overridden procedure has No_Return", New_Op);
1695 end if;
1696
1697 -- If there is no previous operation to override, the type declaration
1698 -- was malformed, and an error must have been emitted already.
1699
1700 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1701 while Present (Elmt)
1702 and then Node (Elmt) /= Prev_Op
1703 loop
1704 Next_Elmt (Elmt);
1705 end loop;
1706
1707 if No (Elmt) then
1708 return;
1709 end if;
1710
1711 Replace_Elmt (Elmt, New_Op);
1712
1713 if Ada_Version >= Ada_05
1714 and then Has_Interfaces (Tagged_Type)
1715 then
1716 -- Ada 2005 (AI-251): Update the attribute alias of all the aliased
1717 -- entities of the overridden primitive to reference New_Op, and also
1718 -- propagate the proper value of Is_Abstract_Subprogram. Verify
1719 -- that the new operation is subtype conformant with the interface
1720 -- operations that it implements (for operations inherited from the
1721 -- parent itself, this check is made when building the derived type).
1722
1723 -- Note: This code is only executed in case of late overriding
1724
1725 Elmt := First_Elmt (Primitive_Operations (Tagged_Type));
1726 while Present (Elmt) loop
1727 Prim := Node (Elmt);
1728
1729 if Prim = New_Op then
1730 null;
1731
1732 -- Note: The check on Is_Subprogram protects the frontend against
1733 -- reading attributes in entities that are not yet fully decorated
1734
1735 elsif Is_Subprogram (Prim)
1736 and then Present (Interface_Alias (Prim))
1737 and then Alias (Prim) = Prev_Op
1738 and then Present (Etype (New_Op))
1739 then
1740 Set_Alias (Prim, New_Op);
1741 Check_Subtype_Conformant (New_Op, Prim);
1742 Set_Is_Abstract_Subprogram (Prim,
1743 Is_Abstract_Subprogram (New_Op));
1744
1745 -- Ensure that this entity will be expanded to fill the
1746 -- corresponding entry in its dispatch table.
1747
1748 if not Is_Abstract_Subprogram (Prim) then
1749 Set_Has_Delayed_Freeze (Prim);
1750 end if;
1751 end if;
1752
1753 Next_Elmt (Elmt);
1754 end loop;
1755 end if;
1756
1757 if (not Is_Package_Or_Generic_Package (Current_Scope))
1758 or else not In_Private_Part (Current_Scope)
1759 then
1760 -- Not a private primitive
1761
1762 null;
1763
1764 else pragma Assert (Is_Inherited_Operation (Prev_Op));
1765
1766 -- Make the overriding operation into an alias of the implicit one.
1767 -- In this fashion a call from outside ends up calling the new body
1768 -- even if non-dispatching, and a call from inside calls the
1769 -- overriding operation because it hides the implicit one. To
1770 -- indicate that the body of Prev_Op is never called, set its
1771 -- dispatch table entity to Empty. If the overridden operation
1772 -- has a dispatching result, so does the overriding one.
1773
1774 Set_Alias (Prev_Op, New_Op);
1775 Set_DTC_Entity (Prev_Op, Empty);
1776 Set_Has_Controlling_Result (New_Op, Has_Controlling_Result (Prev_Op));
1777 return;
1778 end if;
1779 end Override_Dispatching_Operation;
1780
1781 -------------------
1782 -- Propagate_Tag --
1783 -------------------
1784
1785 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is
1786 Call_Node : Node_Id;
1787 Arg : Node_Id;
1788
1789 begin
1790 if Nkind (Actual) = N_Function_Call then
1791 Call_Node := Actual;
1792
1793 elsif Nkind (Actual) = N_Identifier
1794 and then Nkind (Original_Node (Actual)) = N_Function_Call
1795 then
1796 -- Call rewritten as object declaration when stack-checking is
1797 -- enabled. Propagate tag to expression in declaration, which is
1798 -- original call.
1799
1800 Call_Node := Expression (Parent (Entity (Actual)));
1801
1802 -- Ada 2005: If this is a dereference of a call to a function with a
1803 -- dispatching access-result, the tag is propagated when the dereference
1804 -- itself is expanded (see exp_ch6.adb) and there is nothing else to do.
1805
1806 elsif Nkind (Actual) = N_Explicit_Dereference
1807 and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call
1808 then
1809 return;
1810
1811 -- Only other possibilities are parenthesized or qualified expression,
1812 -- or an expander-generated unchecked conversion of a function call to
1813 -- a stream Input attribute.
1814
1815 else
1816 Call_Node := Expression (Actual);
1817 end if;
1818
1819 -- Do not set the Controlling_Argument if already set. This happens in
1820 -- the special case of _Input (see Exp_Attr, case Input).
1821
1822 if No (Controlling_Argument (Call_Node)) then
1823 Set_Controlling_Argument (Call_Node, Control);
1824 end if;
1825
1826 Arg := First_Actual (Call_Node);
1827
1828 while Present (Arg) loop
1829 if Is_Tag_Indeterminate (Arg) then
1830 Propagate_Tag (Control, Arg);
1831 end if;
1832
1833 Next_Actual (Arg);
1834 end loop;
1835
1836 -- Expansion of dispatching calls is suppressed when VM_Target, because
1837 -- the VM back-ends directly handle the generation of dispatching calls
1838 -- and would have to undo any expansion to an indirect call.
1839
1840 if Tagged_Type_Expansion then
1841 Expand_Dispatching_Call (Call_Node);
1842
1843 -- Expansion of a dispatching call results in an indirect call, which in
1844 -- turn causes current values to be killed (see Resolve_Call), so on VM
1845 -- targets we do the call here to ensure consistent warnings between VM
1846 -- and non-VM targets.
1847
1848 else
1849 Kill_Current_Values;
1850 end if;
1851 end Propagate_Tag;
1852
1853 end Sem_Disp;
Mirror of the offical gcc git repository hosted at gcc.gnu.org