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) 1992-2012, 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 26with Atree; use Atree; 27with Debug; use Debug; 28with Elists; use Elists; 29with Einfo; use Einfo; 30with Exp_Disp; use Exp_Disp; 31with Exp_Util; use Exp_Util; 32with Exp_Ch7; use Exp_Ch7; 33with Exp_Tss; use Exp_Tss; 34with Errout; use Errout; 35with Lib.Xref; use Lib.Xref; 36with Namet; use Namet; 37with Nlists; use Nlists; 38with Nmake; use Nmake; 39with Opt; use Opt; 40with Output; use Output; 41with Restrict; use Restrict; 42with Rident; use Rident; 43with Sem; use Sem; 44with Sem_Aux; use Sem_Aux; 45with Sem_Ch3; use Sem_Ch3; 46with Sem_Ch6; use Sem_Ch6; 47with Sem_Eval; use Sem_Eval; 48with Sem_Type; use Sem_Type; 49with Sem_Util; use Sem_Util; 50with Snames; use Snames; 51with Sinfo; use Sinfo; 52with Targparm; use Targparm; 53with Tbuild; use Tbuild; 54with Uintp; use Uintp; 55 56package 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 function Find_Hidden_Overridden_Primitive (S : Entity_Id) return Entity_Id; 77 -- [Ada 2012:AI-0125] Find an inherited hidden primitive of the dispatching 78 -- type of S that has the same name of S, a type-conformant profile, an 79 -- original corresponding operation O that is a primitive of a visible 80 -- ancestor of the dispatching type of S and O is visible at the point of 81 -- of declaration of S. If the entity is found the Alias of S is set to the 82 -- original corresponding operation S and its Overridden_Operation is set 83 -- to the found entity; otherwise return Empty. 84 -- 85 -- This routine does not search for non-hidden primitives since they are 86 -- covered by the normal Ada 2005 rules. 87 88 ------------------------------- 89 -- Add_Dispatching_Operation -- 90 ------------------------------- 91 92 procedure Add_Dispatching_Operation 93 (Tagged_Type : Entity_Id; 94 New_Op : Entity_Id) 95 is 96 List : constant Elist_Id := Primitive_Operations (Tagged_Type); 97 98 begin 99 -- The dispatching operation may already be on the list, if it is the 100 -- wrapper for an inherited function of a null extension (see Exp_Ch3 101 -- for the construction of function wrappers). The list of primitive 102 -- operations must not contain duplicates. 103 104 Append_Unique_Elmt (New_Op, List); 105 end Add_Dispatching_Operation; 106 107 --------------------------- 108 -- Covers_Some_Interface -- 109 --------------------------- 110 111 function Covers_Some_Interface (Prim : Entity_Id) return Boolean is 112 Tagged_Type : constant Entity_Id := Find_Dispatching_Type (Prim); 113 Elmt : Elmt_Id; 114 E : Entity_Id; 115 116 begin 117 pragma Assert (Is_Dispatching_Operation (Prim)); 118 119 -- Although this is a dispatching primitive we must check if its 120 -- dispatching type is available because it may be the primitive 121 -- of a private type not defined as tagged in its partial view. 122 123 if Present (Tagged_Type) and then Has_Interfaces (Tagged_Type) then 124 125 -- If the tagged type is frozen then the internal entities associated 126 -- with interfaces are available in the list of primitives of the 127 -- tagged type and can be used to speed up this search. 128 129 if Is_Frozen (Tagged_Type) then 130 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 131 while Present (Elmt) loop 132 E := Node (Elmt); 133 134 if Present (Interface_Alias (E)) 135 and then Alias (E) = Prim 136 then 137 return True; 138 end if; 139 140 Next_Elmt (Elmt); 141 end loop; 142 143 -- Otherwise we must collect all the interface primitives and check 144 -- if the Prim will override some interface primitive. 145 146 else 147 declare 148 Ifaces_List : Elist_Id; 149 Iface_Elmt : Elmt_Id; 150 Iface : Entity_Id; 151 Iface_Prim : Entity_Id; 152 153 begin 154 Collect_Interfaces (Tagged_Type, Ifaces_List); 155 Iface_Elmt := First_Elmt (Ifaces_List); 156 while Present (Iface_Elmt) loop 157 Iface := Node (Iface_Elmt); 158 159 Elmt := First_Elmt (Primitive_Operations (Iface)); 160 while Present (Elmt) loop 161 Iface_Prim := Node (Elmt); 162 163 if Chars (Iface) = Chars (Prim) 164 and then Is_Interface_Conformant 165 (Tagged_Type, Iface_Prim, Prim) 166 then 167 return True; 168 end if; 169 170 Next_Elmt (Elmt); 171 end loop; 172 173 Next_Elmt (Iface_Elmt); 174 end loop; 175 end; 176 end if; 177 end if; 178 179 return False; 180 end Covers_Some_Interface; 181 182 ------------------------------- 183 -- Check_Controlling_Formals -- 184 ------------------------------- 185 186 procedure Check_Controlling_Formals 187 (Typ : Entity_Id; 188 Subp : Entity_Id) 189 is 190 Formal : Entity_Id; 191 Ctrl_Type : Entity_Id; 192 193 begin 194 Formal := First_Formal (Subp); 195 while Present (Formal) loop 196 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp); 197 198 if Present (Ctrl_Type) then 199 200 -- When controlling type is concurrent and declared within a 201 -- generic or inside an instance use corresponding record type. 202 203 if Is_Concurrent_Type (Ctrl_Type) 204 and then Present (Corresponding_Record_Type (Ctrl_Type)) 205 then 206 Ctrl_Type := Corresponding_Record_Type (Ctrl_Type); 207 end if; 208 209 if Ctrl_Type = Typ then 210 Set_Is_Controlling_Formal (Formal); 211 212 -- Ada 2005 (AI-231): Anonymous access types that are used in 213 -- controlling parameters exclude null because it is necessary 214 -- to read the tag to dispatch, and null has no tag. 215 216 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then 217 Set_Can_Never_Be_Null (Etype (Formal)); 218 Set_Is_Known_Non_Null (Etype (Formal)); 219 end if; 220 221 -- Check that the parameter's nominal subtype statically 222 -- matches the first subtype. 223 224 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then 225 if not Subtypes_Statically_Match 226 (Typ, Designated_Type (Etype (Formal))) 227 then 228 Error_Msg_N 229 ("parameter subtype does not match controlling type", 230 Formal); 231 end if; 232 233 elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) then 234 Error_Msg_N 235 ("parameter subtype does not match controlling type", 236 Formal); 237 end if; 238 239 if Present (Default_Value (Formal)) then 240 241 -- In Ada 2005, access parameters can have defaults 242 243 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type 244 and then Ada_Version < Ada_2005 245 then 246 Error_Msg_N 247 ("default not allowed for controlling access parameter", 248 Default_Value (Formal)); 249 250 elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then 251 Error_Msg_N 252 ("default expression must be a tag indeterminate" & 253 " function call", Default_Value (Formal)); 254 end if; 255 end if; 256 257 elsif Comes_From_Source (Subp) then 258 Error_Msg_N 259 ("operation can be dispatching in only one type", Subp); 260 end if; 261 end if; 262 263 Next_Formal (Formal); 264 end loop; 265 266 if Ekind_In (Subp, E_Function, E_Generic_Function) then 267 Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp); 268 269 if Present (Ctrl_Type) then 270 if Ctrl_Type = Typ then 271 Set_Has_Controlling_Result (Subp); 272 273 -- Check that result subtype statically matches first subtype 274 -- (Ada 2005): Subp may have a controlling access result. 275 276 if Subtypes_Statically_Match (Typ, Etype (Subp)) 277 or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type 278 and then 279 Subtypes_Statically_Match 280 (Typ, Designated_Type (Etype (Subp)))) 281 then 282 null; 283 284 else 285 Error_Msg_N 286 ("result subtype does not match controlling type", Subp); 287 end if; 288 289 elsif Comes_From_Source (Subp) then 290 Error_Msg_N 291 ("operation can be dispatching in only one type", Subp); 292 end if; 293 end if; 294 end if; 295 end Check_Controlling_Formals; 296 297 ---------------------------- 298 -- Check_Controlling_Type -- 299 ---------------------------- 300 301 function Check_Controlling_Type 302 (T : Entity_Id; 303 Subp : Entity_Id) return Entity_Id 304 is 305 Tagged_Type : Entity_Id := Empty; 306 307 begin 308 if Is_Tagged_Type (T) then 309 if Is_First_Subtype (T) then 310 Tagged_Type := T; 311 else 312 Tagged_Type := Base_Type (T); 313 end if; 314 315 elsif Ekind (T) = E_Anonymous_Access_Type 316 and then Is_Tagged_Type (Designated_Type (T)) 317 then 318 if Ekind (Designated_Type (T)) /= E_Incomplete_Type then 319 if Is_First_Subtype (Designated_Type (T)) then 320 Tagged_Type := Designated_Type (T); 321 else 322 Tagged_Type := Base_Type (Designated_Type (T)); 323 end if; 324 325 -- Ada 2005: an incomplete type can be tagged. An operation with an 326 -- access parameter of the type is dispatching. 327 328 elsif Scope (Designated_Type (T)) = Current_Scope then 329 Tagged_Type := Designated_Type (T); 330 331 -- Ada 2005 (AI-50217) 332 333 elsif From_With_Type (Designated_Type (T)) 334 and then Present (Non_Limited_View (Designated_Type (T))) 335 and then Scope (Designated_Type (T)) = Scope (Subp) 336 then 337 if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then 338 Tagged_Type := Non_Limited_View (Designated_Type (T)); 339 else 340 Tagged_Type := Base_Type (Non_Limited_View 341 (Designated_Type (T))); 342 end if; 343 end if; 344 end if; 345 346 if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then 347 return Empty; 348 349 -- The dispatching type and the primitive operation must be defined in 350 -- the same scope, except in the case of internal operations and formal 351 -- abstract subprograms. 352 353 elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp)) 354 and then (not Is_Generic_Type (Tagged_Type) 355 or else not Comes_From_Source (Subp))) 356 or else 357 (Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp)) 358 or else 359 (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration 360 and then 361 Present (Corresponding_Formal_Spec (Parent (Parent (Subp)))) 362 and then 363 Is_Abstract_Subprogram (Subp)) 364 then 365 return Tagged_Type; 366 367 else 368 return Empty; 369 end if; 370 end Check_Controlling_Type; 371 372 ---------------------------- 373 -- Check_Dispatching_Call -- 374 ---------------------------- 375 376 procedure Check_Dispatching_Call (N : Node_Id) is 377 Loc : constant Source_Ptr := Sloc (N); 378 Actual : Node_Id; 379 Formal : Entity_Id; 380 Control : Node_Id := Empty; 381 Func : Entity_Id; 382 Subp_Entity : Entity_Id; 383 Indeterm_Ancestor_Call : Boolean := False; 384 Indeterm_Ctrl_Type : Entity_Id; 385 386 Static_Tag : Node_Id := Empty; 387 -- If a controlling formal has a statically tagged actual, the tag of 388 -- this actual is to be used for any tag-indeterminate actual. 389 390 procedure Check_Direct_Call; 391 -- In the case when the controlling actual is a class-wide type whose 392 -- root type's completion is a task or protected type, the call is in 393 -- fact direct. This routine detects the above case and modifies the 394 -- call accordingly. 395 396 procedure Check_Dispatching_Context; 397 -- If the call is tag-indeterminate and the entity being called is 398 -- abstract, verify that the context is a call that will eventually 399 -- provide a tag for dispatching, or has provided one already. 400 401 ----------------------- 402 -- Check_Direct_Call -- 403 ----------------------- 404 405 procedure Check_Direct_Call is 406 Typ : Entity_Id := Etype (Control); 407 408 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean; 409 -- Determine whether an entity denotes a user-defined equality 410 411 ------------------------------ 412 -- Is_User_Defined_Equality -- 413 ------------------------------ 414 415 function Is_User_Defined_Equality (Id : Entity_Id) return Boolean is 416 begin 417 return 418 Ekind (Id) = E_Function 419 and then Chars (Id) = Name_Op_Eq 420 and then Comes_From_Source (Id) 421 422 -- Internally generated equalities have a full type declaration 423 -- as their parent. 424 425 and then Nkind (Parent (Id)) = N_Function_Specification; 426 end Is_User_Defined_Equality; 427 428 -- Start of processing for Check_Direct_Call 429 430 begin 431 -- Predefined primitives do not receive wrappers since they are built 432 -- from scratch for the corresponding record of synchronized types. 433 -- Equality is in general predefined, but is excluded from the check 434 -- when it is user-defined. 435 436 if Is_Predefined_Dispatching_Operation (Subp_Entity) 437 and then not Is_User_Defined_Equality (Subp_Entity) 438 then 439 return; 440 end if; 441 442 if Is_Class_Wide_Type (Typ) then 443 Typ := Root_Type (Typ); 444 end if; 445 446 if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then 447 Typ := Full_View (Typ); 448 end if; 449 450 if Is_Concurrent_Type (Typ) 451 and then 452 Present (Corresponding_Record_Type (Typ)) 453 then 454 Typ := Corresponding_Record_Type (Typ); 455 456 -- The concurrent record's list of primitives should contain a 457 -- wrapper for the entity of the call, retrieve it. 458 459 declare 460 Prim : Entity_Id; 461 Prim_Elmt : Elmt_Id; 462 Wrapper_Found : Boolean := False; 463 464 begin 465 Prim_Elmt := First_Elmt (Primitive_Operations (Typ)); 466 while Present (Prim_Elmt) loop 467 Prim := Node (Prim_Elmt); 468 469 if Is_Primitive_Wrapper (Prim) 470 and then Wrapped_Entity (Prim) = Subp_Entity 471 then 472 Wrapper_Found := True; 473 exit; 474 end if; 475 476 Next_Elmt (Prim_Elmt); 477 end loop; 478 479 -- A primitive declared between two views should have a 480 -- corresponding wrapper. 481 482 pragma Assert (Wrapper_Found); 483 484 -- Modify the call by setting the proper entity 485 486 Set_Entity (Name (N), Prim); 487 end; 488 end if; 489 end Check_Direct_Call; 490 491 ------------------------------- 492 -- Check_Dispatching_Context -- 493 ------------------------------- 494 495 procedure Check_Dispatching_Context is 496 Subp : constant Entity_Id := Entity (Name (N)); 497 Typ : constant Entity_Id := Etype (Subp); 498 Par : Node_Id; 499 500 procedure Abstract_Context_Error; 501 -- Error for abstract call dispatching on result is not dispatching 502 503 ---------------------------- 504 -- Abstract_Context_Error -- 505 ---------------------------- 506 507 procedure Abstract_Context_Error is 508 begin 509 if Ekind (Subp) = E_Function then 510 Error_Msg_N 511 ("call to abstract function must be dispatching", N); 512 513 -- This error can occur for a procedure in the case of a call to 514 -- an abstract formal procedure with a statically tagged operand. 515 516 else 517 Error_Msg_N 518 ("call to abstract procedure must be dispatching", 519 N); 520 end if; 521 end Abstract_Context_Error; 522 523 -- Start of processing for Check_Dispatching_Context 524 525 begin 526 if Is_Abstract_Subprogram (Subp) 527 and then No (Controlling_Argument (N)) 528 then 529 if Present (Alias (Subp)) 530 and then not Is_Abstract_Subprogram (Alias (Subp)) 531 and then No (DTC_Entity (Subp)) 532 then 533 -- Private overriding of inherited abstract operation, call is 534 -- legal. 535 536 Set_Entity (Name (N), Alias (Subp)); 537 return; 538 539 else 540 -- We need to determine whether the context of the call 541 -- provides a tag to make the call dispatching. This requires 542 -- the call to be the actual in an enclosing call, and that 543 -- actual must be controlling. If the call is an operand of 544 -- equality, the other operand must not ve abstract. 545 546 if not Is_Tagged_Type (Typ) 547 and then not 548 (Ekind (Typ) = E_Anonymous_Access_Type 549 and then Is_Tagged_Type (Designated_Type (Typ))) 550 then 551 Abstract_Context_Error; 552 return; 553 end if; 554 555 Par := Parent (N); 556 557 if Nkind (Par) = N_Parameter_Association then 558 Par := Parent (Par); 559 end if; 560 561 while Present (Par) loop 562 if Nkind_In (Par, N_Function_Call, 563 N_Procedure_Call_Statement) 564 and then Is_Entity_Name (Name (Par)) 565 then 566 declare 567 A : Node_Id; 568 F : Entity_Id; 569 570 begin 571 -- Find formal for which call is the actual. 572 573 F := First_Formal (Entity (Name (Par))); 574 A := First_Actual (Par); 575 while Present (F) loop 576 if Is_Controlling_Formal (F) 577 and then (N = A or else Parent (N) = A) 578 then 579 return; 580 end if; 581 582 Next_Formal (F); 583 Next_Actual (A); 584 end loop; 585 586 Error_Msg_N 587 ("call to abstract function must be dispatching", N); 588 return; 589 end; 590 591 -- For equalitiy operators, one of the operands must be 592 -- statically or dynamically tagged. 593 594 elsif Nkind_In (Par, N_Op_Eq, N_Op_Ne) then 595 if N = Right_Opnd (Par) 596 and then Is_Tag_Indeterminate (Left_Opnd (Par)) 597 then 598 Abstract_Context_Error; 599 600 elsif N = Left_Opnd (Par) 601 and then Is_Tag_Indeterminate (Right_Opnd (Par)) 602 then 603 Abstract_Context_Error; 604 end if; 605 606 return; 607 608 elsif Nkind (Par) = N_Assignment_Statement then 609 return; 610 611 elsif Nkind (Par) = N_Qualified_Expression 612 or else Nkind (Par) = N_Unchecked_Type_Conversion 613 then 614 Par := Parent (Par); 615 616 else 617 Abstract_Context_Error; 618 return; 619 end if; 620 end loop; 621 end if; 622 end if; 623 end Check_Dispatching_Context; 624 625 -- Start of processing for Check_Dispatching_Call 626 627 begin 628 -- Find a controlling argument, if any 629 630 if Present (Parameter_Associations (N)) then 631 Subp_Entity := Entity (Name (N)); 632 633 Actual := First_Actual (N); 634 Formal := First_Formal (Subp_Entity); 635 while Present (Actual) loop 636 Control := Find_Controlling_Arg (Actual); 637 exit when Present (Control); 638 639 -- Check for the case where the actual is a tag-indeterminate call 640 -- whose result type is different than the tagged type associated 641 -- with the containing call, but is an ancestor of the type. 642 643 if Is_Controlling_Formal (Formal) 644 and then Is_Tag_Indeterminate (Actual) 645 and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal)) 646 and then Is_Ancestor (Etype (Actual), Etype (Formal)) 647 then 648 Indeterm_Ancestor_Call := True; 649 Indeterm_Ctrl_Type := Etype (Formal); 650 651 -- If the formal is controlling but the actual is not, the type 652 -- of the actual is statically known, and may be used as the 653 -- controlling tag for some other tag-indeterminate actual. 654 655 elsif Is_Controlling_Formal (Formal) 656 and then Is_Entity_Name (Actual) 657 and then Is_Tagged_Type (Etype (Actual)) 658 then 659 Static_Tag := Actual; 660 end if; 661 662 Next_Actual (Actual); 663 Next_Formal (Formal); 664 end loop; 665 666 -- If the call doesn't have a controlling actual but does have an 667 -- indeterminate actual that requires dispatching treatment, then an 668 -- object is needed that will serve as the controlling argument for 669 -- a dispatching call on the indeterminate actual. This can only 670 -- occur in the unusual situation of a default actual given by 671 -- a tag-indeterminate call and where the type of the call is an 672 -- ancestor of the type associated with a containing call to an 673 -- inherited operation (see AI-239). 674 675 -- Rather than create an object of the tagged type, which would 676 -- be problematic for various reasons (default initialization, 677 -- discriminants), the tag of the containing call's associated 678 -- tagged type is directly used to control the dispatching. 679 680 if No (Control) 681 and then Indeterm_Ancestor_Call 682 and then No (Static_Tag) 683 then 684 Control := 685 Make_Attribute_Reference (Loc, 686 Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc), 687 Attribute_Name => Name_Tag); 688 689 Analyze (Control); 690 end if; 691 692 if Present (Control) then 693 694 -- Verify that no controlling arguments are statically tagged 695 696 if Debug_Flag_E then 697 Write_Str ("Found Dispatching call"); 698 Write_Int (Int (N)); 699 Write_Eol; 700 end if; 701 702 Actual := First_Actual (N); 703 while Present (Actual) loop 704 if Actual /= Control then 705 706 if not Is_Controlling_Actual (Actual) then 707 null; -- Can be anything 708 709 elsif Is_Dynamically_Tagged (Actual) then 710 null; -- Valid parameter 711 712 elsif Is_Tag_Indeterminate (Actual) then 713 714 -- The tag is inherited from the enclosing call (the node 715 -- we are currently analyzing). Explicitly expand the 716 -- actual, since the previous call to Expand (from 717 -- Resolve_Call) had no way of knowing about the 718 -- required dispatching. 719 720 Propagate_Tag (Control, Actual); 721 722 else 723 Error_Msg_N 724 ("controlling argument is not dynamically tagged", 725 Actual); 726 return; 727 end if; 728 end if; 729 730 Next_Actual (Actual); 731 end loop; 732 733 -- Mark call as a dispatching call 734 735 Set_Controlling_Argument (N, Control); 736 Check_Restriction (No_Dispatching_Calls, N); 737 738 -- The dispatching call may need to be converted into a direct 739 -- call in certain cases. 740 741 Check_Direct_Call; 742 743 -- If there is a statically tagged actual and a tag-indeterminate 744 -- call to a function of the ancestor (such as that provided by a 745 -- default), then treat this as a dispatching call and propagate 746 -- the tag to the tag-indeterminate call(s). 747 748 elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then 749 Control := 750 Make_Attribute_Reference (Loc, 751 Prefix => 752 New_Occurrence_Of (Etype (Static_Tag), Loc), 753 Attribute_Name => Name_Tag); 754 755 Analyze (Control); 756 757 Actual := First_Actual (N); 758 Formal := First_Formal (Subp_Entity); 759 while Present (Actual) loop 760 if Is_Tag_Indeterminate (Actual) 761 and then Is_Controlling_Formal (Formal) 762 then 763 Propagate_Tag (Control, Actual); 764 end if; 765 766 Next_Actual (Actual); 767 Next_Formal (Formal); 768 end loop; 769 770 Check_Dispatching_Context; 771 772 else 773 -- The call is not dispatching, so check that there aren't any 774 -- tag-indeterminate abstract calls left. 775 776 Actual := First_Actual (N); 777 while Present (Actual) loop 778 if Is_Tag_Indeterminate (Actual) then 779 780 -- Function call case 781 782 if Nkind (Original_Node (Actual)) = N_Function_Call then 783 Func := Entity (Name (Original_Node (Actual))); 784 785 -- If the actual is an attribute then it can't be abstract 786 -- (the only current case of a tag-indeterminate attribute 787 -- is the stream Input attribute). 788 789 elsif 790 Nkind (Original_Node (Actual)) = N_Attribute_Reference 791 then 792 Func := Empty; 793 794 -- Only other possibility is a qualified expression whose 795 -- constituent expression is itself a call. 796 797 else 798 Func := 799 Entity (Name 800 (Original_Node 801 (Expression (Original_Node (Actual))))); 802 end if; 803 804 if Present (Func) and then Is_Abstract_Subprogram (Func) then 805 Error_Msg_N 806 ("call to abstract function must be dispatching", N); 807 end if; 808 end if; 809 810 Next_Actual (Actual); 811 end loop; 812 813 Check_Dispatching_Context; 814 end if; 815 816 else 817 -- If dispatching on result, the enclosing call, if any, will 818 -- determine the controlling argument. Otherwise this is the 819 -- primitive operation of the root type. 820 821 Check_Dispatching_Context; 822 end if; 823 end Check_Dispatching_Call; 824 825 --------------------------------- 826 -- Check_Dispatching_Operation -- 827 --------------------------------- 828 829 procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id) is 830 Tagged_Type : Entity_Id; 831 Has_Dispatching_Parent : Boolean := False; 832 Body_Is_Last_Primitive : Boolean := False; 833 Ovr_Subp : Entity_Id := Empty; 834 835 begin 836 if not Ekind_In (Subp, E_Procedure, E_Function) then 837 return; 838 end if; 839 840 Set_Is_Dispatching_Operation (Subp, False); 841 Tagged_Type := Find_Dispatching_Type (Subp); 842 843 -- Ada 2005 (AI-345): Use the corresponding record (if available). 844 -- Required because primitives of concurrent types are attached 845 -- to the corresponding record (not to the concurrent type). 846 847 if Ada_Version >= Ada_2005 848 and then Present (Tagged_Type) 849 and then Is_Concurrent_Type (Tagged_Type) 850 and then Present (Corresponding_Record_Type (Tagged_Type)) 851 then 852 Tagged_Type := Corresponding_Record_Type (Tagged_Type); 853 end if; 854 855 -- (AI-345): The task body procedure is not a primitive of the tagged 856 -- type 857 858 if Present (Tagged_Type) 859 and then Is_Concurrent_Record_Type (Tagged_Type) 860 and then Present (Corresponding_Concurrent_Type (Tagged_Type)) 861 and then Is_Task_Type (Corresponding_Concurrent_Type (Tagged_Type)) 862 and then Subp = Get_Task_Body_Procedure 863 (Corresponding_Concurrent_Type (Tagged_Type)) 864 then 865 return; 866 end if; 867 868 -- If Subp is derived from a dispatching operation then it should 869 -- always be treated as dispatching. In this case various checks 870 -- below will be bypassed. Makes sure that late declarations for 871 -- inherited private subprograms are treated as dispatching, even 872 -- if the associated tagged type is already frozen. 873 874 Has_Dispatching_Parent := 875 Present (Alias (Subp)) 876 and then Is_Dispatching_Operation (Alias (Subp)); 877 878 if No (Tagged_Type) then 879 880 -- Ada 2005 (AI-251): Check that Subp is not a primitive associated 881 -- with an abstract interface type unless the interface acts as a 882 -- parent type in a derivation. If the interface type is a formal 883 -- type then the operation is not primitive and therefore legal. 884 885 declare 886 E : Entity_Id; 887 Typ : Entity_Id; 888 889 begin 890 E := First_Entity (Subp); 891 while Present (E) loop 892 893 -- For an access parameter, check designated type 894 895 if Ekind (Etype (E)) = E_Anonymous_Access_Type then 896 Typ := Designated_Type (Etype (E)); 897 else 898 Typ := Etype (E); 899 end if; 900 901 if Comes_From_Source (Subp) 902 and then Is_Interface (Typ) 903 and then not Is_Class_Wide_Type (Typ) 904 and then not Is_Derived_Type (Typ) 905 and then not Is_Generic_Type (Typ) 906 and then not In_Instance 907 then 908 Error_Msg_N ("??declaration of& is too late!", Subp); 909 Error_Msg_NE -- CODEFIX?? 910 ("\??spec should appear immediately after declaration " 911 & "of & !", Subp, Typ); 912 exit; 913 end if; 914 915 Next_Entity (E); 916 end loop; 917 918 -- In case of functions check also the result type 919 920 if Ekind (Subp) = E_Function then 921 if Is_Access_Type (Etype (Subp)) then 922 Typ := Designated_Type (Etype (Subp)); 923 else 924 Typ := Etype (Subp); 925 end if; 926 927 -- The following should be better commented, especially since 928 -- we just added several new conditions here ??? 929 930 if Comes_From_Source (Subp) 931 and then Is_Interface (Typ) 932 and then not Is_Class_Wide_Type (Typ) 933 and then not Is_Derived_Type (Typ) 934 and then not Is_Generic_Type (Typ) 935 and then not In_Instance 936 then 937 Error_Msg_N ("??declaration of& is too late!", Subp); 938 Error_Msg_NE 939 ("\??spec should appear immediately after declaration " 940 & "of & !", Subp, Typ); 941 end if; 942 end if; 943 end; 944 945 return; 946 947 -- The subprograms build internally after the freezing point (such as 948 -- init procs, interface thunks, type support subprograms, and Offset 949 -- to top functions for accessing interface components in variable 950 -- size tagged types) are not primitives. 951 952 elsif Is_Frozen (Tagged_Type) 953 and then not Comes_From_Source (Subp) 954 and then not Has_Dispatching_Parent 955 then 956 -- Complete decoration of internally built subprograms that override 957 -- a dispatching primitive. These entities correspond with the 958 -- following cases: 959 960 -- 1. Ada 2005 (AI-391): Wrapper functions built by the expander 961 -- to override functions of nonabstract null extensions. These 962 -- primitives were added to the list of primitives of the tagged 963 -- type by Make_Controlling_Function_Wrappers. However, attribute 964 -- Is_Dispatching_Operation must be set to true. 965 966 -- 2. Ada 2005 (AI-251): Wrapper procedures of null interface 967 -- primitives. 968 969 -- 3. Subprograms associated with stream attributes (built by 970 -- New_Stream_Subprogram) 971 972 if Present (Old_Subp) 973 and then Present (Overridden_Operation (Subp)) 974 and then Is_Dispatching_Operation (Old_Subp) 975 then 976 pragma Assert 977 ((Ekind (Subp) = E_Function 978 and then Is_Dispatching_Operation (Old_Subp) 979 and then Is_Null_Extension (Base_Type (Etype (Subp)))) 980 or else 981 (Ekind (Subp) = E_Procedure 982 and then Is_Dispatching_Operation (Old_Subp) 983 and then Present (Alias (Old_Subp)) 984 and then Is_Null_Interface_Primitive 985 (Ultimate_Alias (Old_Subp))) 986 or else Get_TSS_Name (Subp) = TSS_Stream_Read 987 or else Get_TSS_Name (Subp) = TSS_Stream_Write); 988 989 Check_Controlling_Formals (Tagged_Type, Subp); 990 Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp); 991 Set_Is_Dispatching_Operation (Subp); 992 end if; 993 994 return; 995 996 -- The operation may be a child unit, whose scope is the defining 997 -- package, but which is not a primitive operation of the type. 998 999 elsif Is_Child_Unit (Subp) then 1000 return; 1001 1002 -- If the subprogram is not defined in a package spec, the only case 1003 -- where it can be a dispatching op is when it overrides an operation 1004 -- before the freezing point of the type. 1005 1006 elsif ((not Is_Package_Or_Generic_Package (Scope (Subp))) 1007 or else In_Package_Body (Scope (Subp))) 1008 and then not Has_Dispatching_Parent 1009 then 1010 if not Comes_From_Source (Subp) 1011 or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type)) 1012 then 1013 null; 1014 1015 -- If the type is already frozen, the overriding is not allowed 1016 -- except when Old_Subp is not a dispatching operation (which can 1017 -- occur when Old_Subp was inherited by an untagged type). However, 1018 -- a body with no previous spec freezes the type *after* its 1019 -- declaration, and therefore is a legal overriding (unless the type 1020 -- has already been frozen). Only the first such body is legal. 1021 1022 elsif Present (Old_Subp) 1023 and then Is_Dispatching_Operation (Old_Subp) 1024 then 1025 if Comes_From_Source (Subp) 1026 and then 1027 (Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body 1028 or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub) 1029 then 1030 declare 1031 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp); 1032 Decl_Item : Node_Id; 1033 1034 begin 1035 -- ??? The checks here for whether the type has been frozen 1036 -- prior to the new body are not complete. It's not simple 1037 -- to check frozenness at this point since the body has 1038 -- already caused the type to be prematurely frozen in 1039 -- Analyze_Declarations, but we're forced to recheck this 1040 -- here because of the odd rule interpretation that allows 1041 -- the overriding if the type wasn't frozen prior to the 1042 -- body. The freezing action should probably be delayed 1043 -- until after the spec is seen, but that's a tricky 1044 -- change to the delicate freezing code. 1045 1046 -- Look at each declaration following the type up until the 1047 -- new subprogram body. If any of the declarations is a body 1048 -- then the type has been frozen already so the overriding 1049 -- primitive is illegal. 1050 1051 Decl_Item := Next (Parent (Tagged_Type)); 1052 while Present (Decl_Item) 1053 and then (Decl_Item /= Subp_Body) 1054 loop 1055 if Comes_From_Source (Decl_Item) 1056 and then (Nkind (Decl_Item) in N_Proper_Body 1057 or else Nkind (Decl_Item) in N_Body_Stub) 1058 then 1059 Error_Msg_N ("overriding of& is too late!", Subp); 1060 Error_Msg_N 1061 ("\spec should appear immediately after the type!", 1062 Subp); 1063 exit; 1064 end if; 1065 1066 Next (Decl_Item); 1067 end loop; 1068 1069 -- If the subprogram doesn't follow in the list of 1070 -- declarations including the type then the type has 1071 -- definitely been frozen already and the body is illegal. 1072 1073 if No (Decl_Item) then 1074 Error_Msg_N ("overriding of& is too late!", Subp); 1075 Error_Msg_N 1076 ("\spec should appear immediately after the type!", 1077 Subp); 1078 1079 elsif Is_Frozen (Subp) then 1080 1081 -- The subprogram body declares a primitive operation. 1082 -- If the subprogram is already frozen, we must update 1083 -- its dispatching information explicitly here. The 1084 -- information is taken from the overridden subprogram. 1085 -- We must also generate a cross-reference entry because 1086 -- references to other primitives were already created 1087 -- when type was frozen. 1088 1089 Body_Is_Last_Primitive := True; 1090 1091 if Present (DTC_Entity (Old_Subp)) then 1092 Set_DTC_Entity (Subp, DTC_Entity (Old_Subp)); 1093 Set_DT_Position (Subp, DT_Position (Old_Subp)); 1094 1095 if not Restriction_Active (No_Dispatching_Calls) then 1096 if Building_Static_DT (Tagged_Type) then 1097 1098 -- If the static dispatch table has not been 1099 -- built then there is nothing else to do now; 1100 -- otherwise we notify that we cannot build the 1101 -- static dispatch table. 1102 1103 if Has_Dispatch_Table (Tagged_Type) then 1104 Error_Msg_N 1105 ("overriding of& is too late for building" & 1106 " static dispatch tables!", Subp); 1107 Error_Msg_N 1108 ("\spec should appear immediately after" & 1109 " the type!", Subp); 1110 end if; 1111 1112 -- No code required to register primitives in VM 1113 -- targets 1114 1115 elsif VM_Target /= No_VM then 1116 null; 1117 1118 else 1119 Insert_Actions_After (Subp_Body, 1120 Register_Primitive (Sloc (Subp_Body), 1121 Prim => Subp)); 1122 end if; 1123 1124 -- Indicate that this is an overriding operation, 1125 -- and replace the overridden entry in the list of 1126 -- primitive operations, which is used for xref 1127 -- generation subsequently. 1128 1129 Generate_Reference (Tagged_Type, Subp, 'P', False); 1130 Override_Dispatching_Operation 1131 (Tagged_Type, Old_Subp, Subp); 1132 end if; 1133 end if; 1134 end if; 1135 end; 1136 1137 else 1138 Error_Msg_N ("overriding of& is too late!", Subp); 1139 Error_Msg_N 1140 ("\subprogram spec should appear immediately after the type!", 1141 Subp); 1142 end if; 1143 1144 -- If the type is not frozen yet and we are not in the overriding 1145 -- case it looks suspiciously like an attempt to define a primitive 1146 -- operation, which requires the declaration to be in a package spec 1147 -- (3.2.3(6)). Only report cases where the type and subprogram are 1148 -- in the same declaration list (by checking the enclosing parent 1149 -- declarations), to avoid spurious warnings on subprograms in 1150 -- instance bodies when the type is declared in the instance spec 1151 -- but hasn't been frozen by the instance body. 1152 1153 elsif not Is_Frozen (Tagged_Type) 1154 and then In_Same_List (Parent (Tagged_Type), Parent (Parent (Subp))) 1155 then 1156 Error_Msg_N 1157 ("??not dispatching (must be defined in a package spec)", Subp); 1158 return; 1159 1160 -- When the type is frozen, it is legitimate to define a new 1161 -- non-primitive operation. 1162 1163 else 1164 return; 1165 end if; 1166 1167 -- Now, we are sure that the scope is a package spec. If the subprogram 1168 -- is declared after the freezing point of the type that's an error 1169 1170 elsif Is_Frozen (Tagged_Type) and then not Has_Dispatching_Parent then 1171 Error_Msg_N ("this primitive operation is declared too late", Subp); 1172 Error_Msg_NE 1173 ("??no primitive operations for& after this line", 1174 Freeze_Node (Tagged_Type), 1175 Tagged_Type); 1176 return; 1177 end if; 1178 1179 Check_Controlling_Formals (Tagged_Type, Subp); 1180 1181 Ovr_Subp := Old_Subp; 1182 1183 -- [Ada 2012:AI-0125]: Search for inherited hidden primitive that may be 1184 -- overridden by Subp 1185 1186 if No (Ovr_Subp) 1187 and then Ada_Version >= Ada_2012 1188 then 1189 Ovr_Subp := Find_Hidden_Overridden_Primitive (Subp); 1190 end if; 1191 1192 -- Now it should be a correct primitive operation, put it in the list 1193 1194 if Present (Ovr_Subp) then 1195 1196 -- If the type has interfaces we complete this check after we set 1197 -- attribute Is_Dispatching_Operation. 1198 1199 Check_Subtype_Conformant (Subp, Ovr_Subp); 1200 1201 if (Chars (Subp) = Name_Initialize 1202 or else Chars (Subp) = Name_Adjust 1203 or else Chars (Subp) = Name_Finalize) 1204 and then Is_Controlled (Tagged_Type) 1205 and then not Is_Visibly_Controlled (Tagged_Type) 1206 then 1207 Set_Overridden_Operation (Subp, Empty); 1208 1209 -- If the subprogram specification carries an overriding 1210 -- indicator, no need for the warning: it is either redundant, 1211 -- or else an error will be reported. 1212 1213 if Nkind (Parent (Subp)) = N_Procedure_Specification 1214 and then 1215 (Must_Override (Parent (Subp)) 1216 or else Must_Not_Override (Parent (Subp))) 1217 then 1218 null; 1219 1220 -- Here we need the warning 1221 1222 else 1223 Error_Msg_NE 1224 ("operation does not override inherited&??", Subp, Subp); 1225 end if; 1226 1227 else 1228 Override_Dispatching_Operation (Tagged_Type, Ovr_Subp, Subp); 1229 1230 -- Ada 2005 (AI-251): In case of late overriding of a primitive 1231 -- that covers abstract interface subprograms we must register it 1232 -- in all the secondary dispatch tables associated with abstract 1233 -- interfaces. We do this now only if not building static tables, 1234 -- nor when the expander is inactive (we avoid trying to register 1235 -- primitives in semantics-only mode, since the type may not have 1236 -- an associated dispatch table). Otherwise the patch code is 1237 -- emitted after those tables are built, to prevent access before 1238 -- elaboration in gigi. 1239 1240 if Body_Is_Last_Primitive and then Full_Expander_Active then 1241 declare 1242 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp); 1243 Elmt : Elmt_Id; 1244 Prim : Node_Id; 1245 1246 begin 1247 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 1248 while Present (Elmt) loop 1249 Prim := Node (Elmt); 1250 1251 -- No code required to register primitives in VM targets 1252 1253 if Present (Alias (Prim)) 1254 and then Present (Interface_Alias (Prim)) 1255 and then Alias (Prim) = Subp 1256 and then not Building_Static_DT (Tagged_Type) 1257 and then VM_Target = No_VM 1258 then 1259 Insert_Actions_After (Subp_Body, 1260 Register_Primitive (Sloc (Subp_Body), Prim => Prim)); 1261 end if; 1262 1263 Next_Elmt (Elmt); 1264 end loop; 1265 1266 -- Redisplay the contents of the updated dispatch table 1267 1268 if Debug_Flag_ZZ then 1269 Write_Str ("Late overriding: "); 1270 Write_DT (Tagged_Type); 1271 end if; 1272 end; 1273 end if; 1274 end if; 1275 1276 -- If the tagged type is a concurrent type then we must be compiling 1277 -- with no code generation (we are either compiling a generic unit or 1278 -- compiling under -gnatc mode) because we have previously tested that 1279 -- no serious errors has been reported. In this case we do not add the 1280 -- primitive to the list of primitives of Tagged_Type but we leave the 1281 -- primitive decorated as a dispatching operation to be able to analyze 1282 -- and report errors associated with the Object.Operation notation. 1283 1284 elsif Is_Concurrent_Type (Tagged_Type) then 1285 pragma Assert (not Expander_Active); 1286 null; 1287 1288 -- If no old subprogram, then we add this as a dispatching operation, 1289 -- but we avoid doing this if an error was posted, to prevent annoying 1290 -- cascaded errors. 1291 1292 elsif not Error_Posted (Subp) then 1293 Add_Dispatching_Operation (Tagged_Type, Subp); 1294 end if; 1295 1296 Set_Is_Dispatching_Operation (Subp, True); 1297 1298 -- Ada 2005 (AI-251): If the type implements interfaces we must check 1299 -- subtype conformance against all the interfaces covered by this 1300 -- primitive. 1301 1302 if Present (Ovr_Subp) 1303 and then Has_Interfaces (Tagged_Type) 1304 then 1305 declare 1306 Ifaces_List : Elist_Id; 1307 Iface_Elmt : Elmt_Id; 1308 Iface_Prim_Elmt : Elmt_Id; 1309 Iface_Prim : Entity_Id; 1310 Ret_Typ : Entity_Id; 1311 1312 begin 1313 Collect_Interfaces (Tagged_Type, Ifaces_List); 1314 1315 Iface_Elmt := First_Elmt (Ifaces_List); 1316 while Present (Iface_Elmt) loop 1317 if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then 1318 Iface_Prim_Elmt := 1319 First_Elmt (Primitive_Operations (Node (Iface_Elmt))); 1320 while Present (Iface_Prim_Elmt) loop 1321 Iface_Prim := Node (Iface_Prim_Elmt); 1322 1323 if Is_Interface_Conformant 1324 (Tagged_Type, Iface_Prim, Subp) 1325 then 1326 -- Handle procedures, functions whose return type 1327 -- matches, or functions not returning interfaces 1328 1329 if Ekind (Subp) = E_Procedure 1330 or else Etype (Iface_Prim) = Etype (Subp) 1331 or else not Is_Interface (Etype (Iface_Prim)) 1332 then 1333 Check_Subtype_Conformant 1334 (New_Id => Subp, 1335 Old_Id => Iface_Prim, 1336 Err_Loc => Subp, 1337 Skip_Controlling_Formals => True); 1338 1339 -- Handle functions returning interfaces 1340 1341 elsif Implements_Interface 1342 (Etype (Subp), Etype (Iface_Prim)) 1343 then 1344 -- Temporarily force both entities to return the 1345 -- same type. Required because Subtype_Conformant 1346 -- does not handle this case. 1347 1348 Ret_Typ := Etype (Iface_Prim); 1349 Set_Etype (Iface_Prim, Etype (Subp)); 1350 1351 Check_Subtype_Conformant 1352 (New_Id => Subp, 1353 Old_Id => Iface_Prim, 1354 Err_Loc => Subp, 1355 Skip_Controlling_Formals => True); 1356 1357 Set_Etype (Iface_Prim, Ret_Typ); 1358 end if; 1359 end if; 1360 1361 Next_Elmt (Iface_Prim_Elmt); 1362 end loop; 1363 end if; 1364 1365 Next_Elmt (Iface_Elmt); 1366 end loop; 1367 end; 1368 end if; 1369 1370 if not Body_Is_Last_Primitive then 1371 Set_DT_Position (Subp, No_Uint); 1372 1373 elsif Has_Controlled_Component (Tagged_Type) 1374 and then 1375 (Chars (Subp) = Name_Initialize or else 1376 Chars (Subp) = Name_Adjust or else 1377 Chars (Subp) = Name_Finalize or else 1378 Chars (Subp) = Name_Finalize_Address) 1379 then 1380 declare 1381 F_Node : constant Node_Id := Freeze_Node (Tagged_Type); 1382 Decl : Node_Id; 1383 Old_P : Entity_Id; 1384 Old_Bod : Node_Id; 1385 Old_Spec : Entity_Id; 1386 1387 C_Names : constant array (1 .. 4) of Name_Id := 1388 (Name_Initialize, 1389 Name_Adjust, 1390 Name_Finalize, 1391 Name_Finalize_Address); 1392 1393 D_Names : constant array (1 .. 4) of TSS_Name_Type := 1394 (TSS_Deep_Initialize, 1395 TSS_Deep_Adjust, 1396 TSS_Deep_Finalize, 1397 TSS_Finalize_Address); 1398 1399 begin 1400 -- Remove previous controlled function which was constructed and 1401 -- analyzed when the type was frozen. This requires removing the 1402 -- body of the redefined primitive, as well as its specification 1403 -- if needed (there is no spec created for Deep_Initialize, see 1404 -- exp_ch3.adb). We must also dismantle the exception information 1405 -- that may have been generated for it when front end zero-cost 1406 -- tables are enabled. 1407 1408 for J in D_Names'Range loop 1409 Old_P := TSS (Tagged_Type, D_Names (J)); 1410 1411 if Present (Old_P) 1412 and then Chars (Subp) = C_Names (J) 1413 then 1414 Old_Bod := Unit_Declaration_Node (Old_P); 1415 Remove (Old_Bod); 1416 Set_Is_Eliminated (Old_P); 1417 Set_Scope (Old_P, Scope (Current_Scope)); 1418 1419 if Nkind (Old_Bod) = N_Subprogram_Body 1420 and then Present (Corresponding_Spec (Old_Bod)) 1421 then 1422 Old_Spec := Corresponding_Spec (Old_Bod); 1423 Set_Has_Completion (Old_Spec, False); 1424 end if; 1425 end if; 1426 end loop; 1427 1428 Build_Late_Proc (Tagged_Type, Chars (Subp)); 1429 1430 -- The new operation is added to the actions of the freeze node 1431 -- for the type, but this node has already been analyzed, so we 1432 -- must retrieve and analyze explicitly the new body. 1433 1434 if Present (F_Node) 1435 and then Present (Actions (F_Node)) 1436 then 1437 Decl := Last (Actions (F_Node)); 1438 Analyze (Decl); 1439 end if; 1440 end; 1441 end if; 1442 end Check_Dispatching_Operation; 1443 1444 ------------------------------------------ 1445 -- Check_Operation_From_Incomplete_Type -- 1446 ------------------------------------------ 1447 1448 procedure Check_Operation_From_Incomplete_Type 1449 (Subp : Entity_Id; 1450 Typ : Entity_Id) 1451 is 1452 Full : constant Entity_Id := Full_View (Typ); 1453 Parent_Typ : constant Entity_Id := Etype (Full); 1454 Old_Prim : constant Elist_Id := Primitive_Operations (Parent_Typ); 1455 New_Prim : constant Elist_Id := Primitive_Operations (Full); 1456 Op1, Op2 : Elmt_Id; 1457 Prev : Elmt_Id := No_Elmt; 1458 1459 function Derives_From (Parent_Subp : Entity_Id) return Boolean; 1460 -- Check that Subp has profile of an operation derived from Parent_Subp. 1461 -- Subp must have a parameter or result type that is Typ or an access 1462 -- parameter or access result type that designates Typ. 1463 1464 ------------------ 1465 -- Derives_From -- 1466 ------------------ 1467 1468 function Derives_From (Parent_Subp : Entity_Id) return Boolean is 1469 F1, F2 : Entity_Id; 1470 1471 begin 1472 if Chars (Parent_Subp) /= Chars (Subp) then 1473 return False; 1474 end if; 1475 1476 -- Check that the type of controlling formals is derived from the 1477 -- parent subprogram's controlling formal type (or designated type 1478 -- if the formal type is an anonymous access type). 1479 1480 F1 := First_Formal (Parent_Subp); 1481 F2 := First_Formal (Subp); 1482 while Present (F1) and then Present (F2) loop 1483 if Ekind (Etype (F1)) = E_Anonymous_Access_Type then 1484 if Ekind (Etype (F2)) /= E_Anonymous_Access_Type then 1485 return False; 1486 elsif Designated_Type (Etype (F1)) = Parent_Typ 1487 and then Designated_Type (Etype (F2)) /= Full 1488 then 1489 return False; 1490 end if; 1491 1492 elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then 1493 return False; 1494 1495 elsif Etype (F1) = Parent_Typ and then Etype (F2) /= Full then 1496 return False; 1497 end if; 1498 1499 Next_Formal (F1); 1500 Next_Formal (F2); 1501 end loop; 1502 1503 -- Check that a controlling result type is derived from the parent 1504 -- subprogram's result type (or designated type if the result type 1505 -- is an anonymous access type). 1506 1507 if Ekind (Parent_Subp) = E_Function then 1508 if Ekind (Subp) /= E_Function then 1509 return False; 1510 1511 elsif Ekind (Etype (Parent_Subp)) = E_Anonymous_Access_Type then 1512 if Ekind (Etype (Subp)) /= E_Anonymous_Access_Type then 1513 return False; 1514 1515 elsif Designated_Type (Etype (Parent_Subp)) = Parent_Typ 1516 and then Designated_Type (Etype (Subp)) /= Full 1517 then 1518 return False; 1519 end if; 1520 1521 elsif Ekind (Etype (Subp)) = E_Anonymous_Access_Type then 1522 return False; 1523 1524 elsif Etype (Parent_Subp) = Parent_Typ 1525 and then Etype (Subp) /= Full 1526 then 1527 return False; 1528 end if; 1529 1530 elsif Ekind (Subp) = E_Function then 1531 return False; 1532 end if; 1533 1534 return No (F1) and then No (F2); 1535 end Derives_From; 1536 1537 -- Start of processing for Check_Operation_From_Incomplete_Type 1538 1539 begin 1540 -- The operation may override an inherited one, or may be a new one 1541 -- altogether. The inherited operation will have been hidden by the 1542 -- current one at the point of the type derivation, so it does not 1543 -- appear in the list of primitive operations of the type. We have to 1544 -- find the proper place of insertion in the list of primitive opera- 1545 -- tions by iterating over the list for the parent type. 1546 1547 Op1 := First_Elmt (Old_Prim); 1548 Op2 := First_Elmt (New_Prim); 1549 while Present (Op1) and then Present (Op2) loop 1550 if Derives_From (Node (Op1)) then 1551 if No (Prev) then 1552 1553 -- Avoid adding it to the list of primitives if already there! 1554 1555 if Node (Op2) /= Subp then 1556 Prepend_Elmt (Subp, New_Prim); 1557 end if; 1558 1559 else 1560 Insert_Elmt_After (Subp, Prev); 1561 end if; 1562 1563 return; 1564 end if; 1565 1566 Prev := Op2; 1567 Next_Elmt (Op1); 1568 Next_Elmt (Op2); 1569 end loop; 1570 1571 -- Operation is a new primitive 1572 1573 Append_Elmt (Subp, New_Prim); 1574 end Check_Operation_From_Incomplete_Type; 1575 1576 --------------------------------------- 1577 -- Check_Operation_From_Private_View -- 1578 --------------------------------------- 1579 1580 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is 1581 Tagged_Type : Entity_Id; 1582 1583 begin 1584 if Is_Dispatching_Operation (Alias (Subp)) then 1585 Set_Scope (Subp, Current_Scope); 1586 Tagged_Type := Find_Dispatching_Type (Subp); 1587 1588 -- Add Old_Subp to primitive operations if not already present 1589 1590 if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then 1591 Append_Unique_Elmt (Old_Subp, Primitive_Operations (Tagged_Type)); 1592 1593 -- If Old_Subp isn't already marked as dispatching then this is 1594 -- the case of an operation of an untagged private type fulfilled 1595 -- by a tagged type that overrides an inherited dispatching 1596 -- operation, so we set the necessary dispatching attributes here. 1597 1598 if not Is_Dispatching_Operation (Old_Subp) then 1599 1600 -- If the untagged type has no discriminants, and the full 1601 -- view is constrained, there will be a spurious mismatch of 1602 -- subtypes on the controlling arguments, because the tagged 1603 -- type is the internal base type introduced in the derivation. 1604 -- Use the original type to verify conformance, rather than the 1605 -- base type. 1606 1607 if not Comes_From_Source (Tagged_Type) 1608 and then Has_Discriminants (Tagged_Type) 1609 then 1610 declare 1611 Formal : Entity_Id; 1612 1613 begin 1614 Formal := First_Formal (Old_Subp); 1615 while Present (Formal) loop 1616 if Tagged_Type = Base_Type (Etype (Formal)) then 1617 Tagged_Type := Etype (Formal); 1618 end if; 1619 1620 Next_Formal (Formal); 1621 end loop; 1622 end; 1623 1624 if Tagged_Type = Base_Type (Etype (Old_Subp)) then 1625 Tagged_Type := Etype (Old_Subp); 1626 end if; 1627 end if; 1628 1629 Check_Controlling_Formals (Tagged_Type, Old_Subp); 1630 Set_Is_Dispatching_Operation (Old_Subp, True); 1631 Set_DT_Position (Old_Subp, No_Uint); 1632 end if; 1633 1634 -- If the old subprogram is an explicit renaming of some other 1635 -- entity, it is not overridden by the inherited subprogram. 1636 -- Otherwise, update its alias and other attributes. 1637 1638 if Present (Alias (Old_Subp)) 1639 and then Nkind (Unit_Declaration_Node (Old_Subp)) /= 1640 N_Subprogram_Renaming_Declaration 1641 then 1642 Set_Alias (Old_Subp, Alias (Subp)); 1643 1644 -- The derived subprogram should inherit the abstractness of 1645 -- the parent subprogram (except in the case of a function 1646 -- returning the type). This sets the abstractness properly 1647 -- for cases where a private extension may have inherited an 1648 -- abstract operation, but the full type is derived from a 1649 -- descendant type and inherits a nonabstract version. 1650 1651 if Etype (Subp) /= Tagged_Type then 1652 Set_Is_Abstract_Subprogram 1653 (Old_Subp, Is_Abstract_Subprogram (Alias (Subp))); 1654 end if; 1655 end if; 1656 end if; 1657 end if; 1658 end Check_Operation_From_Private_View; 1659 1660 -------------------------- 1661 -- Find_Controlling_Arg -- 1662 -------------------------- 1663 1664 function Find_Controlling_Arg (N : Node_Id) return Node_Id is 1665 Orig_Node : constant Node_Id := Original_Node (N); 1666 Typ : Entity_Id; 1667 1668 begin 1669 if Nkind (Orig_Node) = N_Qualified_Expression then 1670 return Find_Controlling_Arg (Expression (Orig_Node)); 1671 end if; 1672 1673 -- Dispatching on result case. If expansion is disabled, the node still 1674 -- has the structure of a function call. However, if the function name 1675 -- is an operator and the call was given in infix form, the original 1676 -- node has no controlling result and we must examine the current node. 1677 1678 if Nkind (N) = N_Function_Call 1679 and then Present (Controlling_Argument (N)) 1680 and then Has_Controlling_Result (Entity (Name (N))) 1681 then 1682 return Controlling_Argument (N); 1683 1684 -- If expansion is enabled, the call may have been transformed into 1685 -- an indirect call, and we need to recover the original node. 1686 1687 elsif Nkind (Orig_Node) = N_Function_Call 1688 and then Present (Controlling_Argument (Orig_Node)) 1689 and then Has_Controlling_Result (Entity (Name (Orig_Node))) 1690 then 1691 return Controlling_Argument (Orig_Node); 1692 1693 -- Type conversions are dynamically tagged if the target type, or its 1694 -- designated type, are classwide. An interface conversion expands into 1695 -- a dereference, so test must be performed on the original node. 1696 1697 elsif Nkind (Orig_Node) = N_Type_Conversion 1698 and then Nkind (N) = N_Explicit_Dereference 1699 and then Is_Controlling_Actual (N) 1700 then 1701 declare 1702 Target_Type : constant Entity_Id := 1703 Entity (Subtype_Mark (Orig_Node)); 1704 1705 begin 1706 if Is_Class_Wide_Type (Target_Type) then 1707 return N; 1708 1709 elsif Is_Access_Type (Target_Type) 1710 and then Is_Class_Wide_Type (Designated_Type (Target_Type)) 1711 then 1712 return N; 1713 1714 else 1715 return Empty; 1716 end if; 1717 end; 1718 1719 -- Normal case 1720 1721 elsif Is_Controlling_Actual (N) 1722 or else 1723 (Nkind (Parent (N)) = N_Qualified_Expression 1724 and then Is_Controlling_Actual (Parent (N))) 1725 then 1726 Typ := Etype (N); 1727 1728 if Is_Access_Type (Typ) then 1729 1730 -- In the case of an Access attribute, use the type of the prefix, 1731 -- since in the case of an actual for an access parameter, the 1732 -- attribute's type may be of a specific designated type, even 1733 -- though the prefix type is class-wide. 1734 1735 if Nkind (N) = N_Attribute_Reference then 1736 Typ := Etype (Prefix (N)); 1737 1738 -- An allocator is dispatching if the type of qualified expression 1739 -- is class_wide, in which case this is the controlling type. 1740 1741 elsif Nkind (Orig_Node) = N_Allocator 1742 and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression 1743 then 1744 Typ := Etype (Expression (Orig_Node)); 1745 else 1746 Typ := Designated_Type (Typ); 1747 end if; 1748 end if; 1749 1750 if Is_Class_Wide_Type (Typ) 1751 or else 1752 (Nkind (Parent (N)) = N_Qualified_Expression 1753 and then Is_Access_Type (Etype (N)) 1754 and then Is_Class_Wide_Type (Designated_Type (Etype (N)))) 1755 then 1756 return N; 1757 end if; 1758 end if; 1759 1760 return Empty; 1761 end Find_Controlling_Arg; 1762 1763 --------------------------- 1764 -- Find_Dispatching_Type -- 1765 --------------------------- 1766 1767 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is 1768 A_Formal : Entity_Id; 1769 Formal : Entity_Id; 1770 Ctrl_Type : Entity_Id; 1771 1772 begin 1773 if Ekind_In (Subp, E_Function, E_Procedure) 1774 and then Present (DTC_Entity (Subp)) 1775 then 1776 return Scope (DTC_Entity (Subp)); 1777 1778 -- For subprograms internally generated by derivations of tagged types 1779 -- use the alias subprogram as a reference to locate the dispatching 1780 -- type of Subp. 1781 1782 elsif not Comes_From_Source (Subp) 1783 and then Present (Alias (Subp)) 1784 and then Is_Dispatching_Operation (Alias (Subp)) 1785 then 1786 if Ekind (Alias (Subp)) = E_Function 1787 and then Has_Controlling_Result (Alias (Subp)) 1788 then 1789 return Check_Controlling_Type (Etype (Subp), Subp); 1790 1791 else 1792 Formal := First_Formal (Subp); 1793 A_Formal := First_Formal (Alias (Subp)); 1794 while Present (A_Formal) loop 1795 if Is_Controlling_Formal (A_Formal) then 1796 return Check_Controlling_Type (Etype (Formal), Subp); 1797 end if; 1798 1799 Next_Formal (Formal); 1800 Next_Formal (A_Formal); 1801 end loop; 1802 1803 pragma Assert (False); 1804 return Empty; 1805 end if; 1806 1807 -- General case 1808 1809 else 1810 Formal := First_Formal (Subp); 1811 while Present (Formal) loop 1812 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp); 1813 1814 if Present (Ctrl_Type) then 1815 return Ctrl_Type; 1816 end if; 1817 1818 Next_Formal (Formal); 1819 end loop; 1820 1821 -- The subprogram may also be dispatching on result 1822 1823 if Present (Etype (Subp)) then 1824 return Check_Controlling_Type (Etype (Subp), Subp); 1825 end if; 1826 end if; 1827 1828 pragma Assert (not Is_Dispatching_Operation (Subp)); 1829 return Empty; 1830 end Find_Dispatching_Type; 1831 1832 -------------------------------------- 1833 -- Find_Hidden_Overridden_Primitive -- 1834 -------------------------------------- 1835 1836 function Find_Hidden_Overridden_Primitive (S : Entity_Id) return Entity_Id 1837 is 1838 Tag_Typ : constant Entity_Id := Find_Dispatching_Type (S); 1839 Elmt : Elmt_Id; 1840 Orig_Prim : Entity_Id; 1841 Prim : Entity_Id; 1842 Vis_List : Elist_Id; 1843 1844 begin 1845 -- This Ada 2012 rule is valid only for type extensions or private 1846 -- extensions. 1847 1848 if No (Tag_Typ) 1849 or else not Is_Record_Type (Tag_Typ) 1850 or else Etype (Tag_Typ) = Tag_Typ 1851 then 1852 return Empty; 1853 end if; 1854 1855 -- Collect the list of visible ancestor of the tagged type 1856 1857 Vis_List := Visible_Ancestors (Tag_Typ); 1858 1859 Elmt := First_Elmt (Primitive_Operations (Tag_Typ)); 1860 while Present (Elmt) loop 1861 Prim := Node (Elmt); 1862 1863 -- Find an inherited hidden dispatching primitive with the name of S 1864 -- and a type-conformant profile. 1865 1866 if Present (Alias (Prim)) 1867 and then Is_Hidden (Alias (Prim)) 1868 and then Find_Dispatching_Type (Alias (Prim)) /= Tag_Typ 1869 and then Primitive_Names_Match (S, Prim) 1870 and then Type_Conformant (S, Prim) 1871 then 1872 declare 1873 Vis_Ancestor : Elmt_Id; 1874 Elmt : Elmt_Id; 1875 1876 begin 1877 -- The original corresponding operation of Prim must be an 1878 -- operation of a visible ancestor of the dispatching type S, 1879 -- and the original corresponding operation of S2 must be 1880 -- visible. 1881 1882 Orig_Prim := Original_Corresponding_Operation (Prim); 1883 1884 if Orig_Prim /= Prim 1885 and then Is_Immediately_Visible (Orig_Prim) 1886 then 1887 Vis_Ancestor := First_Elmt (Vis_List); 1888 while Present (Vis_Ancestor) loop 1889 Elmt := 1890 First_Elmt (Primitive_Operations (Node (Vis_Ancestor))); 1891 while Present (Elmt) loop 1892 if Node (Elmt) = Orig_Prim then 1893 Set_Overridden_Operation (S, Prim); 1894 Set_Alias (Prim, Orig_Prim); 1895 return Prim; 1896 end if; 1897 1898 Next_Elmt (Elmt); 1899 end loop; 1900 1901 Next_Elmt (Vis_Ancestor); 1902 end loop; 1903 end if; 1904 end; 1905 end if; 1906 1907 Next_Elmt (Elmt); 1908 end loop; 1909 1910 return Empty; 1911 end Find_Hidden_Overridden_Primitive; 1912 1913 --------------------------------------- 1914 -- Find_Primitive_Covering_Interface -- 1915 --------------------------------------- 1916 1917 function Find_Primitive_Covering_Interface 1918 (Tagged_Type : Entity_Id; 1919 Iface_Prim : Entity_Id) return Entity_Id 1920 is 1921 E : Entity_Id; 1922 El : Elmt_Id; 1923 1924 begin 1925 pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim)) 1926 or else (Present (Alias (Iface_Prim)) 1927 and then 1928 Is_Interface 1929 (Find_Dispatching_Type (Ultimate_Alias (Iface_Prim))))); 1930 1931 -- Search in the homonym chain. Done to speed up locating visible 1932 -- entities and required to catch primitives associated with the partial 1933 -- view of private types when processing the corresponding full view. 1934 1935 E := Current_Entity (Iface_Prim); 1936 while Present (E) loop 1937 if Is_Subprogram (E) 1938 and then Is_Dispatching_Operation (E) 1939 and then Is_Interface_Conformant (Tagged_Type, Iface_Prim, E) 1940 then 1941 return E; 1942 end if; 1943 1944 E := Homonym (E); 1945 end loop; 1946 1947 -- Search in the list of primitives of the type. Required to locate 1948 -- the covering primitive if the covering primitive is not visible 1949 -- (for example, non-visible inherited primitive of private type). 1950 1951 El := First_Elmt (Primitive_Operations (Tagged_Type)); 1952 while Present (El) loop 1953 E := Node (El); 1954 1955 -- Keep separate the management of internal entities that link 1956 -- primitives with interface primitives from tagged type primitives. 1957 1958 if No (Interface_Alias (E)) then 1959 if Present (Alias (E)) then 1960 1961 -- This interface primitive has not been covered yet 1962 1963 if Alias (E) = Iface_Prim then 1964 return E; 1965 1966 -- The covering primitive was inherited 1967 1968 elsif Overridden_Operation (Ultimate_Alias (E)) 1969 = Iface_Prim 1970 then 1971 return E; 1972 end if; 1973 end if; 1974 1975 -- Check if E covers the interface primitive (includes case in 1976 -- which E is an inherited private primitive). 1977 1978 if Is_Interface_Conformant (Tagged_Type, Iface_Prim, E) then 1979 return E; 1980 end if; 1981 1982 -- Use the internal entity that links the interface primitive with 1983 -- the covering primitive to locate the entity. 1984 1985 elsif Interface_Alias (E) = Iface_Prim then 1986 return Alias (E); 1987 end if; 1988 1989 Next_Elmt (El); 1990 end loop; 1991 1992 -- Not found 1993 1994 return Empty; 1995 end Find_Primitive_Covering_Interface; 1996 1997 --------------------------- 1998 -- Inherited_Subprograms -- 1999 --------------------------- 2000 2001 function Inherited_Subprograms (S : Entity_Id) return Subprogram_List is 2002 Result : Subprogram_List (1 .. 6000); 2003 -- 6000 here is intended to be infinity. We could use an expandable 2004 -- table, but it would be awfully heavy, and there is no way that we 2005 -- could reasonably exceed this value. 2006 2007 N : Int := 0; 2008 -- Number of entries in Result 2009 2010 Parent_Op : Entity_Id; 2011 -- Traverses the Overridden_Operation chain 2012 2013 procedure Store_IS (E : Entity_Id); 2014 -- Stores E in Result if not already stored 2015 2016 -------------- 2017 -- Store_IS -- 2018 -------------- 2019 2020 procedure Store_IS (E : Entity_Id) is 2021 begin 2022 for J in 1 .. N loop 2023 if E = Result (J) then 2024 return; 2025 end if; 2026 end loop; 2027 2028 N := N + 1; 2029 Result (N) := E; 2030 end Store_IS; 2031 2032 -- Start of processing for Inherited_Subprograms 2033 2034 begin 2035 if Present (S) and then Is_Dispatching_Operation (S) then 2036 2037 -- Deal with direct inheritance 2038 2039 Parent_Op := S; 2040 loop 2041 Parent_Op := Overridden_Operation (Parent_Op); 2042 exit when No (Parent_Op); 2043 2044 if Is_Subprogram (Parent_Op) 2045 or else Is_Generic_Subprogram (Parent_Op) 2046 then 2047 Store_IS (Parent_Op); 2048 end if; 2049 end loop; 2050 2051 -- Now deal with interfaces 2052 2053 declare 2054 Tag_Typ : Entity_Id; 2055 Prim : Entity_Id; 2056 Elmt : Elmt_Id; 2057 2058 begin 2059 Tag_Typ := Find_Dispatching_Type (S); 2060 2061 if Is_Concurrent_Type (Tag_Typ) then 2062 Tag_Typ := Corresponding_Record_Type (Tag_Typ); 2063 end if; 2064 2065 -- Search primitive operations of dispatching type 2066 2067 if Present (Tag_Typ) 2068 and then Present (Primitive_Operations (Tag_Typ)) 2069 then 2070 Elmt := First_Elmt (Primitive_Operations (Tag_Typ)); 2071 while Present (Elmt) loop 2072 Prim := Node (Elmt); 2073 2074 -- The following test eliminates some odd cases in which 2075 -- Ekind (Prim) is Void, to be investigated further ??? 2076 2077 if not (Is_Subprogram (Prim) 2078 or else 2079 Is_Generic_Subprogram (Prim)) 2080 then 2081 null; 2082 2083 -- For [generic] subprogram, look at interface alias 2084 2085 elsif Present (Interface_Alias (Prim)) 2086 and then Alias (Prim) = S 2087 then 2088 -- We have found a primitive covered by S 2089 2090 Store_IS (Interface_Alias (Prim)); 2091 end if; 2092 2093 Next_Elmt (Elmt); 2094 end loop; 2095 end if; 2096 end; 2097 end if; 2098 2099 return Result (1 .. N); 2100 end Inherited_Subprograms; 2101 2102 --------------------------- 2103 -- Is_Dynamically_Tagged -- 2104 --------------------------- 2105 2106 function Is_Dynamically_Tagged (N : Node_Id) return Boolean is 2107 begin 2108 if Nkind (N) = N_Error then 2109 return False; 2110 else 2111 return Find_Controlling_Arg (N) /= Empty; 2112 end if; 2113 end Is_Dynamically_Tagged; 2114 2115 --------------------------------- 2116 -- Is_Null_Interface_Primitive -- 2117 --------------------------------- 2118 2119 function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean is 2120 begin 2121 return Comes_From_Source (E) 2122 and then Is_Dispatching_Operation (E) 2123 and then Ekind (E) = E_Procedure 2124 and then Null_Present (Parent (E)) 2125 and then Is_Interface (Find_Dispatching_Type (E)); 2126 end Is_Null_Interface_Primitive; 2127 2128 -------------------------- 2129 -- Is_Tag_Indeterminate -- 2130 -------------------------- 2131 2132 function Is_Tag_Indeterminate (N : Node_Id) return Boolean is 2133 Nam : Entity_Id; 2134 Actual : Node_Id; 2135 Orig_Node : constant Node_Id := Original_Node (N); 2136 2137 begin 2138 if Nkind (Orig_Node) = N_Function_Call 2139 and then Is_Entity_Name (Name (Orig_Node)) 2140 then 2141 Nam := Entity (Name (Orig_Node)); 2142 2143 if not Has_Controlling_Result (Nam) then 2144 return False; 2145 2146 -- The function may have a controlling result, but if the return type 2147 -- is not visibly tagged, then this is not tag-indeterminate. 2148 2149 elsif Is_Access_Type (Etype (Nam)) 2150 and then not Is_Tagged_Type (Designated_Type (Etype (Nam))) 2151 then 2152 return False; 2153 2154 -- An explicit dereference means that the call has already been 2155 -- expanded and there is no tag to propagate. 2156 2157 elsif Nkind (N) = N_Explicit_Dereference then 2158 return False; 2159 2160 -- If there are no actuals, the call is tag-indeterminate 2161 2162 elsif No (Parameter_Associations (Orig_Node)) then 2163 return True; 2164 2165 else 2166 Actual := First_Actual (Orig_Node); 2167 while Present (Actual) loop 2168 if Is_Controlling_Actual (Actual) 2169 and then not Is_Tag_Indeterminate (Actual) 2170 then 2171 -- One operand is dispatching 2172 2173 return False; 2174 end if; 2175 2176 Next_Actual (Actual); 2177 end loop; 2178 2179 return True; 2180 end if; 2181 2182 elsif Nkind (Orig_Node) = N_Qualified_Expression then 2183 return Is_Tag_Indeterminate (Expression (Orig_Node)); 2184 2185 -- Case of a call to the Input attribute (possibly rewritten), which is 2186 -- always tag-indeterminate except when its prefix is a Class attribute. 2187 2188 elsif Nkind (Orig_Node) = N_Attribute_Reference 2189 and then 2190 Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input 2191 and then 2192 Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference 2193 then 2194 return True; 2195 2196 -- In Ada 2005, a function that returns an anonymous access type can be 2197 -- dispatching, and the dereference of a call to such a function can 2198 -- also be tag-indeterminate if the call itself is. 2199 2200 elsif Nkind (Orig_Node) = N_Explicit_Dereference 2201 and then Ada_Version >= Ada_2005 2202 then 2203 return Is_Tag_Indeterminate (Prefix (Orig_Node)); 2204 2205 else 2206 return False; 2207 end if; 2208 end Is_Tag_Indeterminate; 2209 2210 ------------------------------------ 2211 -- Override_Dispatching_Operation -- 2212 ------------------------------------ 2213 2214 procedure Override_Dispatching_Operation 2215 (Tagged_Type : Entity_Id; 2216 Prev_Op : Entity_Id; 2217 New_Op : Entity_Id; 2218 Is_Wrapper : Boolean := False) 2219 is 2220 Elmt : Elmt_Id; 2221 Prim : Node_Id; 2222 2223 begin 2224 -- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but 2225 -- we do it unconditionally in Ada 95 now, since this is our pragma!) 2226 2227 if No_Return (Prev_Op) and then not No_Return (New_Op) then 2228 Error_Msg_N ("procedure & must have No_Return pragma", New_Op); 2229 Error_Msg_N ("\since overridden procedure has No_Return", New_Op); 2230 end if; 2231 2232 -- If there is no previous operation to override, the type declaration 2233 -- was malformed, and an error must have been emitted already. 2234 2235 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 2236 while Present (Elmt) 2237 and then Node (Elmt) /= Prev_Op 2238 loop 2239 Next_Elmt (Elmt); 2240 end loop; 2241 2242 if No (Elmt) then 2243 return; 2244 end if; 2245 2246 -- The location of entities that come from source in the list of 2247 -- primitives of the tagged type must follow their order of occurrence 2248 -- in the sources to fulfill the C++ ABI. If the overridden entity is a 2249 -- primitive of an interface that is not implemented by the parents of 2250 -- this tagged type (that is, it is an alias of an interface primitive 2251 -- generated by Derive_Interface_Progenitors), then we must append the 2252 -- new entity at the end of the list of primitives. 2253 2254 if Present (Alias (Prev_Op)) 2255 and then Etype (Tagged_Type) /= Tagged_Type 2256 and then Is_Interface (Find_Dispatching_Type (Alias (Prev_Op))) 2257 and then not Is_Ancestor (Find_Dispatching_Type (Alias (Prev_Op)), 2258 Tagged_Type, Use_Full_View => True) 2259 and then not Implements_Interface 2260 (Etype (Tagged_Type), 2261 Find_Dispatching_Type (Alias (Prev_Op))) 2262 then 2263 Remove_Elmt (Primitive_Operations (Tagged_Type), Elmt); 2264 Append_Elmt (New_Op, Primitive_Operations (Tagged_Type)); 2265 2266 -- The new primitive replaces the overridden entity. Required to ensure 2267 -- that overriding primitive is assigned the same dispatch table slot. 2268 2269 else 2270 Replace_Elmt (Elmt, New_Op); 2271 end if; 2272 2273 if Ada_Version >= Ada_2005 2274 and then Has_Interfaces (Tagged_Type) 2275 then 2276 -- Ada 2005 (AI-251): Update the attribute alias of all the aliased 2277 -- entities of the overridden primitive to reference New_Op, and 2278 -- also propagate the proper value of Is_Abstract_Subprogram. Verify 2279 -- that the new operation is subtype conformant with the interface 2280 -- operations that it implements (for operations inherited from the 2281 -- parent itself, this check is made when building the derived type). 2282 2283 -- Note: This code is executed with internally generated wrappers of 2284 -- functions with controlling result and late overridings. 2285 2286 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 2287 while Present (Elmt) loop 2288 Prim := Node (Elmt); 2289 2290 if Prim = New_Op then 2291 null; 2292 2293 -- Note: The check on Is_Subprogram protects the frontend against 2294 -- reading attributes in entities that are not yet fully decorated 2295 2296 elsif Is_Subprogram (Prim) 2297 and then Present (Interface_Alias (Prim)) 2298 and then Alias (Prim) = Prev_Op 2299 then 2300 Set_Alias (Prim, New_Op); 2301 2302 -- No further decoration needed yet for internally generated 2303 -- wrappers of controlling functions since (at this stage) 2304 -- they are not yet decorated. 2305 2306 if not Is_Wrapper then 2307 Check_Subtype_Conformant (New_Op, Prim); 2308 2309 Set_Is_Abstract_Subprogram (Prim, 2310 Is_Abstract_Subprogram (New_Op)); 2311 2312 -- Ensure that this entity will be expanded to fill the 2313 -- corresponding entry in its dispatch table. 2314 2315 if not Is_Abstract_Subprogram (Prim) then 2316 Set_Has_Delayed_Freeze (Prim); 2317 end if; 2318 end if; 2319 end if; 2320 2321 Next_Elmt (Elmt); 2322 end loop; 2323 end if; 2324 2325 if (not Is_Package_Or_Generic_Package (Current_Scope)) 2326 or else not In_Private_Part (Current_Scope) 2327 then 2328 -- Not a private primitive 2329 2330 null; 2331 2332 else pragma Assert (Is_Inherited_Operation (Prev_Op)); 2333 2334 -- Make the overriding operation into an alias of the implicit one. 2335 -- In this fashion a call from outside ends up calling the new body 2336 -- even if non-dispatching, and a call from inside calls the over- 2337 -- riding operation because it hides the implicit one. To indicate 2338 -- that the body of Prev_Op is never called, set its dispatch table 2339 -- entity to Empty. If the overridden operation has a dispatching 2340 -- result, so does the overriding one. 2341 2342 Set_Alias (Prev_Op, New_Op); 2343 Set_DTC_Entity (Prev_Op, Empty); 2344 Set_Has_Controlling_Result (New_Op, Has_Controlling_Result (Prev_Op)); 2345 return; 2346 end if; 2347 end Override_Dispatching_Operation; 2348 2349 ------------------- 2350 -- Propagate_Tag -- 2351 ------------------- 2352 2353 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is 2354 Call_Node : Node_Id; 2355 Arg : Node_Id; 2356 2357 begin 2358 if Nkind (Actual) = N_Function_Call then 2359 Call_Node := Actual; 2360 2361 elsif Nkind (Actual) = N_Identifier 2362 and then Nkind (Original_Node (Actual)) = N_Function_Call 2363 then 2364 -- Call rewritten as object declaration when stack-checking is 2365 -- enabled. Propagate tag to expression in declaration, which is 2366 -- original call. 2367 2368 Call_Node := Expression (Parent (Entity (Actual))); 2369 2370 -- Ada 2005: If this is a dereference of a call to a function with a 2371 -- dispatching access-result, the tag is propagated when the dereference 2372 -- itself is expanded (see exp_ch6.adb) and there is nothing else to do. 2373 2374 elsif Nkind (Actual) = N_Explicit_Dereference 2375 and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call 2376 then 2377 return; 2378 2379 -- When expansion is suppressed, an unexpanded call to 'Input can occur, 2380 -- and in that case we can simply return. 2381 2382 elsif Nkind (Actual) = N_Attribute_Reference then 2383 pragma Assert (Attribute_Name (Actual) = Name_Input); 2384 2385 return; 2386 2387 -- Only other possibilities are parenthesized or qualified expression, 2388 -- or an expander-generated unchecked conversion of a function call to 2389 -- a stream Input attribute. 2390 2391 else 2392 Call_Node := Expression (Actual); 2393 end if; 2394 2395 -- No action needed if the call has been already expanded 2396 2397 if Is_Expanded_Dispatching_Call (Call_Node) then 2398 return; 2399 end if; 2400 2401 -- Do not set the Controlling_Argument if already set. This happens in 2402 -- the special case of _Input (see Exp_Attr, case Input). 2403 2404 if No (Controlling_Argument (Call_Node)) then 2405 Set_Controlling_Argument (Call_Node, Control); 2406 end if; 2407 2408 Arg := First_Actual (Call_Node); 2409 while Present (Arg) loop 2410 if Is_Tag_Indeterminate (Arg) then 2411 Propagate_Tag (Control, Arg); 2412 end if; 2413 2414 Next_Actual (Arg); 2415 end loop; 2416 2417 -- Expansion of dispatching calls is suppressed when VM_Target, because 2418 -- the VM back-ends directly handle the generation of dispatching calls 2419 -- and would have to undo any expansion to an indirect call. 2420 2421 if Tagged_Type_Expansion then 2422 declare 2423 Call_Typ : constant Entity_Id := Etype (Call_Node); 2424 2425 begin 2426 Expand_Dispatching_Call (Call_Node); 2427 2428 -- If the controlling argument is an interface type and the type 2429 -- of Call_Node differs then we must add an implicit conversion to 2430 -- force displacement of the pointer to the object to reference 2431 -- the secondary dispatch table of the interface. 2432 2433 if Is_Interface (Etype (Control)) 2434 and then Etype (Control) /= Call_Typ 2435 then 2436 -- Cannot use Convert_To because the previous call to 2437 -- Expand_Dispatching_Call leaves decorated the Call_Node 2438 -- with the type of Control. 2439 2440 Rewrite (Call_Node, 2441 Make_Type_Conversion (Sloc (Call_Node), 2442 Subtype_Mark => 2443 New_Occurrence_Of (Etype (Control), Sloc (Call_Node)), 2444 Expression => Relocate_Node (Call_Node))); 2445 Set_Etype (Call_Node, Etype (Control)); 2446 Set_Analyzed (Call_Node); 2447 2448 Expand_Interface_Conversion (Call_Node, Is_Static => False); 2449 end if; 2450 end; 2451 2452 -- Expansion of a dispatching call results in an indirect call, which in 2453 -- turn causes current values to be killed (see Resolve_Call), so on VM 2454 -- targets we do the call here to ensure consistent warnings between VM 2455 -- and non-VM targets. 2456 2457 else 2458 Kill_Current_Values; 2459 end if; 2460 end Propagate_Tag; 2461 2462end Sem_Disp; 2463