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) 1992-2019, 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_Ch8; use Sem_Ch8; 48with Sem_Eval; use Sem_Eval; 49with Sem_Type; use Sem_Type; 50with Sem_Util; use Sem_Util; 51with Snames; use Snames; 52with Sinfo; use Sinfo; 53with Tbuild; use Tbuild; 54with Uintp; use Uintp; 55with Warnsw; use Warnsw; 56 57package body Sem_Disp is 58 59 ----------------------- 60 -- Local Subprograms -- 61 ----------------------- 62 63 procedure Add_Dispatching_Operation 64 (Tagged_Type : Entity_Id; 65 New_Op : Entity_Id); 66 -- Add New_Op in the list of primitive operations of Tagged_Type 67 68 function Check_Controlling_Type 69 (T : Entity_Id; 70 Subp : Entity_Id) return Entity_Id; 71 -- T is the tagged type of a formal parameter or the result of Subp. 72 -- If the subprogram has a controlling parameter or result that matches 73 -- the type, then returns the tagged type of that parameter or result 74 -- (returning the designated tagged type in the case of an access 75 -- parameter); otherwise returns empty. 76 77 function Find_Hidden_Overridden_Primitive (S : Entity_Id) return Entity_Id; 78 -- [Ada 2012:AI-0125] Find an inherited hidden primitive of the dispatching 79 -- type of S that has the same name of S, a type-conformant profile, an 80 -- original corresponding operation O that is a primitive of a visible 81 -- ancestor of the dispatching type of S and O is visible at the point of 82 -- of declaration of S. If the entity is found the Alias of S is set to the 83 -- original corresponding operation S and its Overridden_Operation is set 84 -- to the found entity; otherwise return Empty. 85 -- 86 -- This routine does not search for non-hidden primitives since they are 87 -- covered by the normal Ada 2005 rules. 88 89 function Is_Inherited_Public_Operation (Op : Entity_Id) return Boolean; 90 -- Check whether a primitive operation is inherited from an operation 91 -- declared in the visible part of its package. 92 93 ------------------------------- 94 -- Add_Dispatching_Operation -- 95 ------------------------------- 96 97 procedure Add_Dispatching_Operation 98 (Tagged_Type : Entity_Id; 99 New_Op : Entity_Id) 100 is 101 List : constant Elist_Id := Primitive_Operations (Tagged_Type); 102 103 begin 104 -- The dispatching operation may already be on the list, if it is the 105 -- wrapper for an inherited function of a null extension (see Exp_Ch3 106 -- for the construction of function wrappers). The list of primitive 107 -- operations must not contain duplicates. 108 109 -- The Default_Initial_Condition and invariant procedures are not added 110 -- to the list of primitives even when they are generated for a tagged 111 -- type. These routines must not be targets of dispatching calls and 112 -- therefore must not appear in the dispatch table because they already 113 -- utilize class-wide-precondition semantics to handle inheritance and 114 -- overriding. 115 116 if Is_Suitable_Primitive (New_Op) then 117 Append_Unique_Elmt (New_Op, List); 118 end if; 119 end Add_Dispatching_Operation; 120 121 -------------------------- 122 -- Covered_Interface_Op -- 123 -------------------------- 124 125 function Covered_Interface_Op (Prim : Entity_Id) return Entity_Id is 126 Tagged_Type : constant Entity_Id := Find_Dispatching_Type (Prim); 127 Elmt : Elmt_Id; 128 E : Entity_Id; 129 130 begin 131 pragma Assert (Is_Dispatching_Operation (Prim)); 132 133 -- Although this is a dispatching primitive we must check if its 134 -- dispatching type is available because it may be the primitive 135 -- of a private type not defined as tagged in its partial view. 136 137 if Present (Tagged_Type) and then Has_Interfaces (Tagged_Type) then 138 139 -- If the tagged type is frozen then the internal entities associated 140 -- with interfaces are available in the list of primitives of the 141 -- tagged type and can be used to speed up this search. 142 143 if Is_Frozen (Tagged_Type) then 144 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 145 while Present (Elmt) loop 146 E := Node (Elmt); 147 148 if Present (Interface_Alias (E)) 149 and then Alias (E) = Prim 150 then 151 return Interface_Alias (E); 152 end if; 153 154 Next_Elmt (Elmt); 155 end loop; 156 157 -- Otherwise we must collect all the interface primitives and check 158 -- if the Prim overrides (implements) some interface primitive. 159 160 else 161 declare 162 Ifaces_List : Elist_Id; 163 Iface_Elmt : Elmt_Id; 164 Iface : Entity_Id; 165 Iface_Prim : Entity_Id; 166 167 begin 168 Collect_Interfaces (Tagged_Type, Ifaces_List); 169 Iface_Elmt := First_Elmt (Ifaces_List); 170 while Present (Iface_Elmt) loop 171 Iface := Node (Iface_Elmt); 172 173 Elmt := First_Elmt (Primitive_Operations (Iface)); 174 while Present (Elmt) loop 175 Iface_Prim := Node (Elmt); 176 177 if Chars (Iface_Prim) = Chars (Prim) 178 and then Is_Interface_Conformant 179 (Tagged_Type, Iface_Prim, Prim) 180 then 181 return Iface_Prim; 182 end if; 183 184 Next_Elmt (Elmt); 185 end loop; 186 187 Next_Elmt (Iface_Elmt); 188 end loop; 189 end; 190 end if; 191 end if; 192 193 return Empty; 194 end Covered_Interface_Op; 195 196 ------------------------------- 197 -- Check_Controlling_Formals -- 198 ------------------------------- 199 200 procedure Check_Controlling_Formals 201 (Typ : Entity_Id; 202 Subp : Entity_Id) 203 is 204 Formal : Entity_Id; 205 Ctrl_Type : Entity_Id; 206 207 begin 208 Formal := First_Formal (Subp); 209 while Present (Formal) loop 210 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp); 211 212 if Present (Ctrl_Type) then 213 214 -- When controlling type is concurrent and declared within a 215 -- generic or inside an instance use corresponding record type. 216 217 if Is_Concurrent_Type (Ctrl_Type) 218 and then Present (Corresponding_Record_Type (Ctrl_Type)) 219 then 220 Ctrl_Type := Corresponding_Record_Type (Ctrl_Type); 221 end if; 222 223 if Ctrl_Type = Typ then 224 Set_Is_Controlling_Formal (Formal); 225 226 -- Ada 2005 (AI-231): Anonymous access types that are used in 227 -- controlling parameters exclude null because it is necessary 228 -- to read the tag to dispatch, and null has no tag. 229 230 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then 231 Set_Can_Never_Be_Null (Etype (Formal)); 232 Set_Is_Known_Non_Null (Etype (Formal)); 233 end if; 234 235 -- Check that the parameter's nominal subtype statically 236 -- matches the first subtype. 237 238 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type then 239 if not Subtypes_Statically_Match 240 (Typ, Designated_Type (Etype (Formal))) 241 then 242 Error_Msg_N 243 ("parameter subtype does not match controlling type", 244 Formal); 245 end if; 246 247 -- Within a predicate function, the formal may be a subtype 248 -- of a tagged type, given that the predicate is expressed 249 -- in terms of the subtype. 250 251 elsif not Subtypes_Statically_Match (Typ, Etype (Formal)) 252 and then not Is_Predicate_Function (Subp) 253 then 254 Error_Msg_N 255 ("parameter subtype does not match controlling type", 256 Formal); 257 end if; 258 259 if Present (Default_Value (Formal)) then 260 261 -- In Ada 2005, access parameters can have defaults 262 263 if Ekind (Etype (Formal)) = E_Anonymous_Access_Type 264 and then Ada_Version < Ada_2005 265 then 266 Error_Msg_N 267 ("default not allowed for controlling access parameter", 268 Default_Value (Formal)); 269 270 elsif not Is_Tag_Indeterminate (Default_Value (Formal)) then 271 Error_Msg_N 272 ("default expression must be a tag indeterminate" & 273 " function call", Default_Value (Formal)); 274 end if; 275 end if; 276 277 elsif Comes_From_Source (Subp) then 278 Error_Msg_N 279 ("operation can be dispatching in only one type", Subp); 280 end if; 281 end if; 282 283 Next_Formal (Formal); 284 end loop; 285 286 if Ekind_In (Subp, E_Function, E_Generic_Function) then 287 Ctrl_Type := Check_Controlling_Type (Etype (Subp), Subp); 288 289 if Present (Ctrl_Type) then 290 if Ctrl_Type = Typ then 291 Set_Has_Controlling_Result (Subp); 292 293 -- Check that result subtype statically matches first subtype 294 -- (Ada 2005): Subp may have a controlling access result. 295 296 if Subtypes_Statically_Match (Typ, Etype (Subp)) 297 or else (Ekind (Etype (Subp)) = E_Anonymous_Access_Type 298 and then 299 Subtypes_Statically_Match 300 (Typ, Designated_Type (Etype (Subp)))) 301 then 302 null; 303 304 else 305 Error_Msg_N 306 ("result subtype does not match controlling type", Subp); 307 end if; 308 309 elsif Comes_From_Source (Subp) then 310 Error_Msg_N 311 ("operation can be dispatching in only one type", Subp); 312 end if; 313 end if; 314 end if; 315 end Check_Controlling_Formals; 316 317 ---------------------------- 318 -- Check_Controlling_Type -- 319 ---------------------------- 320 321 function Check_Controlling_Type 322 (T : Entity_Id; 323 Subp : Entity_Id) return Entity_Id 324 is 325 Tagged_Type : Entity_Id := Empty; 326 327 begin 328 if Is_Tagged_Type (T) then 329 if Is_First_Subtype (T) then 330 Tagged_Type := T; 331 else 332 Tagged_Type := Base_Type (T); 333 end if; 334 335 -- If the type is incomplete, it may have been declared without a 336 -- Tagged indication, but the full view may be tagged, in which case 337 -- that is the controlling type of the subprogram. This is one of the 338 -- approx. 579 places in the language where a lookahead would help. 339 340 elsif Ekind (T) = E_Incomplete_Type 341 and then Present (Full_View (T)) 342 and then Is_Tagged_Type (Full_View (T)) 343 then 344 Set_Is_Tagged_Type (T); 345 Tagged_Type := Full_View (T); 346 347 elsif Ekind (T) = E_Anonymous_Access_Type 348 and then Is_Tagged_Type (Designated_Type (T)) 349 then 350 if Ekind (Designated_Type (T)) /= E_Incomplete_Type then 351 if Is_First_Subtype (Designated_Type (T)) then 352 Tagged_Type := Designated_Type (T); 353 else 354 Tagged_Type := Base_Type (Designated_Type (T)); 355 end if; 356 357 -- Ada 2005: an incomplete type can be tagged. An operation with an 358 -- access parameter of the type is dispatching. 359 360 elsif Scope (Designated_Type (T)) = Current_Scope then 361 Tagged_Type := Designated_Type (T); 362 363 -- Ada 2005 (AI-50217) 364 365 elsif From_Limited_With (Designated_Type (T)) 366 and then Has_Non_Limited_View (Designated_Type (T)) 367 and then Scope (Designated_Type (T)) = Scope (Subp) 368 then 369 if Is_First_Subtype (Non_Limited_View (Designated_Type (T))) then 370 Tagged_Type := Non_Limited_View (Designated_Type (T)); 371 else 372 Tagged_Type := Base_Type (Non_Limited_View 373 (Designated_Type (T))); 374 end if; 375 end if; 376 end if; 377 378 if No (Tagged_Type) or else Is_Class_Wide_Type (Tagged_Type) then 379 return Empty; 380 381 -- The dispatching type and the primitive operation must be defined in 382 -- the same scope, except in the case of internal operations and formal 383 -- abstract subprograms. 384 385 elsif ((Scope (Subp) = Scope (Tagged_Type) or else Is_Internal (Subp)) 386 and then (not Is_Generic_Type (Tagged_Type) 387 or else not Comes_From_Source (Subp))) 388 or else 389 (Is_Formal_Subprogram (Subp) and then Is_Abstract_Subprogram (Subp)) 390 or else 391 (Nkind (Parent (Parent (Subp))) = N_Subprogram_Renaming_Declaration 392 and then 393 Present (Corresponding_Formal_Spec (Parent (Parent (Subp)))) 394 and then 395 Is_Abstract_Subprogram (Subp)) 396 then 397 return Tagged_Type; 398 399 else 400 return Empty; 401 end if; 402 end Check_Controlling_Type; 403 404 ---------------------------- 405 -- Check_Dispatching_Call -- 406 ---------------------------- 407 408 procedure Check_Dispatching_Call (N : Node_Id) is 409 Loc : constant Source_Ptr := Sloc (N); 410 Actual : Node_Id; 411 Formal : Entity_Id; 412 Control : Node_Id := Empty; 413 Func : Entity_Id; 414 Subp_Entity : Entity_Id; 415 Indeterm_Ancestor_Call : Boolean := False; 416 Indeterm_Ctrl_Type : Entity_Id := Empty; -- init to avoid warning 417 418 Static_Tag : Node_Id := Empty; 419 -- If a controlling formal has a statically tagged actual, the tag of 420 -- this actual is to be used for any tag-indeterminate actual. 421 422 procedure Check_Direct_Call; 423 -- In the case when the controlling actual is a class-wide type whose 424 -- root type's completion is a task or protected type, the call is in 425 -- fact direct. This routine detects the above case and modifies the 426 -- call accordingly. 427 428 procedure Check_Dispatching_Context (Call : Node_Id); 429 -- If the call is tag-indeterminate and the entity being called is 430 -- abstract, verify that the context is a call that will eventually 431 -- provide a tag for dispatching, or has provided one already. 432 433 ----------------------- 434 -- Check_Direct_Call -- 435 ----------------------- 436 437 procedure Check_Direct_Call is 438 Typ : Entity_Id := Etype (Control); 439 begin 440 -- Predefined primitives do not receive wrappers since they are built 441 -- from scratch for the corresponding record of synchronized types. 442 -- Equality is in general predefined, but is excluded from the check 443 -- when it is user-defined. 444 445 if Is_Predefined_Dispatching_Operation (Subp_Entity) 446 and then not Is_User_Defined_Equality (Subp_Entity) 447 then 448 return; 449 end if; 450 451 if Is_Class_Wide_Type (Typ) then 452 Typ := Root_Type (Typ); 453 end if; 454 455 if Is_Private_Type (Typ) and then Present (Full_View (Typ)) then 456 Typ := Full_View (Typ); 457 end if; 458 459 if Is_Concurrent_Type (Typ) 460 and then 461 Present (Corresponding_Record_Type (Typ)) 462 then 463 Typ := Corresponding_Record_Type (Typ); 464 465 -- The concurrent record's list of primitives should contain a 466 -- wrapper for the entity of the call, retrieve it. 467 468 declare 469 Prim : Entity_Id; 470 Prim_Elmt : Elmt_Id; 471 Wrapper_Found : Boolean := False; 472 473 begin 474 Prim_Elmt := First_Elmt (Primitive_Operations (Typ)); 475 while Present (Prim_Elmt) loop 476 Prim := Node (Prim_Elmt); 477 478 if Is_Primitive_Wrapper (Prim) 479 and then Wrapped_Entity (Prim) = Subp_Entity 480 then 481 Wrapper_Found := True; 482 exit; 483 end if; 484 485 Next_Elmt (Prim_Elmt); 486 end loop; 487 488 -- A primitive declared between two views should have a 489 -- corresponding wrapper. 490 491 pragma Assert (Wrapper_Found); 492 493 -- Modify the call by setting the proper entity 494 495 Set_Entity (Name (N), Prim); 496 end; 497 end if; 498 end Check_Direct_Call; 499 500 ------------------------------- 501 -- Check_Dispatching_Context -- 502 ------------------------------- 503 504 procedure Check_Dispatching_Context (Call : Node_Id) is 505 Subp : constant Entity_Id := Entity (Name (Call)); 506 507 procedure Abstract_Context_Error; 508 -- Error for abstract call dispatching on result is not dispatching 509 510 ---------------------------- 511 -- Abstract_Context_Error -- 512 ---------------------------- 513 514 procedure Abstract_Context_Error is 515 begin 516 if Ekind (Subp) = E_Function then 517 Error_Msg_N 518 ("call to abstract function must be dispatching", N); 519 520 -- This error can occur for a procedure in the case of a call to 521 -- an abstract formal procedure with a statically tagged operand. 522 523 else 524 Error_Msg_N 525 ("call to abstract procedure must be dispatching", N); 526 end if; 527 end Abstract_Context_Error; 528 529 -- Local variables 530 531 Scop : constant Entity_Id := Current_Scope_No_Loops; 532 Typ : constant Entity_Id := Etype (Subp); 533 Par : Node_Id; 534 535 -- Start of processing for Check_Dispatching_Context 536 537 begin 538 -- If the called subprogram is a private overriding, replace it 539 -- with its alias, which has the correct body. Verify that the 540 -- two subprograms have the same controlling type (this is not the 541 -- case for an inherited subprogram that has become abstract). 542 543 if Is_Abstract_Subprogram (Subp) 544 and then No (Controlling_Argument (Call)) 545 then 546 if Present (Alias (Subp)) 547 and then not Is_Abstract_Subprogram (Alias (Subp)) 548 and then No (DTC_Entity (Subp)) 549 and then Find_Dispatching_Type (Subp) = 550 Find_Dispatching_Type (Alias (Subp)) 551 then 552 -- Private overriding of inherited abstract operation, call is 553 -- legal. 554 555 Set_Entity (Name (N), Alias (Subp)); 556 return; 557 558 -- An obscure special case: a null procedure may have a class- 559 -- wide pre/postcondition that includes a call to an abstract 560 -- subp. Calls within the expression may not have been rewritten 561 -- as dispatching calls yet, because the null body appears in 562 -- the current declarative part. The expression will be properly 563 -- rewritten/reanalyzed when the postcondition procedure is built. 564 565 -- Similarly, if this is a pre/postcondition for an abstract 566 -- subprogram, it may call another abstract function which is 567 -- a primitive of an abstract type. The call is non-dispatching 568 -- but will be legal in overridings of the operation. 569 570 elsif (Is_Subprogram (Scop) 571 or else Chars (Scop) = Name_Postcondition) 572 and then 573 (Is_Abstract_Subprogram (Scop) 574 or else 575 (Nkind (Parent (Scop)) = N_Procedure_Specification 576 and then Null_Present (Parent (Scop)))) 577 then 578 null; 579 580 elsif Ekind (Current_Scope) = E_Function 581 and then Nkind (Unit_Declaration_Node (Scop)) = 582 N_Generic_Subprogram_Declaration 583 then 584 null; 585 586 else 587 -- We need to determine whether the context of the call 588 -- provides a tag to make the call dispatching. This requires 589 -- the call to be the actual in an enclosing call, and that 590 -- actual must be controlling. If the call is an operand of 591 -- equality, the other operand must not ve abstract. 592 593 if not Is_Tagged_Type (Typ) 594 and then not 595 (Ekind (Typ) = E_Anonymous_Access_Type 596 and then Is_Tagged_Type (Designated_Type (Typ))) 597 then 598 Abstract_Context_Error; 599 return; 600 end if; 601 602 Par := Parent (Call); 603 604 if Nkind (Par) = N_Parameter_Association then 605 Par := Parent (Par); 606 end if; 607 608 if Nkind (Par) = N_Qualified_Expression 609 or else Nkind (Par) = N_Unchecked_Type_Conversion 610 then 611 Par := Parent (Par); 612 end if; 613 614 if Nkind_In (Par, N_Function_Call, N_Procedure_Call_Statement) 615 and then Is_Entity_Name (Name (Par)) 616 then 617 declare 618 Enc_Subp : constant Entity_Id := Entity (Name (Par)); 619 A : Node_Id; 620 F : Entity_Id; 621 Control : Entity_Id; 622 Ret_Type : Entity_Id; 623 624 begin 625 -- Find controlling formal that can provide tag for the 626 -- tag-indeterminate actual. The corresponding actual 627 -- must be the corresponding class-wide type. 628 629 F := First_Formal (Enc_Subp); 630 A := First_Actual (Par); 631 632 -- Find controlling type of call. Dereference if function 633 -- returns an access type. 634 635 Ret_Type := Etype (Call); 636 if Is_Access_Type (Etype (Call)) then 637 Ret_Type := Designated_Type (Ret_Type); 638 end if; 639 640 while Present (F) loop 641 Control := Etype (A); 642 643 if Is_Access_Type (Control) then 644 Control := Designated_Type (Control); 645 end if; 646 647 if Is_Controlling_Formal (F) 648 and then not (Call = A or else Parent (Call) = A) 649 and then Control = Class_Wide_Type (Ret_Type) 650 then 651 return; 652 end if; 653 654 Next_Formal (F); 655 Next_Actual (A); 656 end loop; 657 658 if Nkind (Par) = N_Function_Call 659 and then Is_Tag_Indeterminate (Par) 660 then 661 -- The parent may be an actual of an enclosing call 662 663 Check_Dispatching_Context (Par); 664 return; 665 666 else 667 Error_Msg_N 668 ("call to abstract function must be dispatching", 669 Call); 670 return; 671 end if; 672 end; 673 674 -- For equality operators, one of the operands must be 675 -- statically or dynamically tagged. 676 677 elsif Nkind_In (Par, N_Op_Eq, N_Op_Ne) then 678 if N = Right_Opnd (Par) 679 and then Is_Tag_Indeterminate (Left_Opnd (Par)) 680 then 681 Abstract_Context_Error; 682 683 elsif N = Left_Opnd (Par) 684 and then Is_Tag_Indeterminate (Right_Opnd (Par)) 685 then 686 Abstract_Context_Error; 687 end if; 688 689 return; 690 691 -- The left-hand side of an assignment provides the tag 692 693 elsif Nkind (Par) = N_Assignment_Statement then 694 return; 695 696 else 697 Abstract_Context_Error; 698 end if; 699 end if; 700 end if; 701 end Check_Dispatching_Context; 702 703 -- Start of processing for Check_Dispatching_Call 704 705 begin 706 -- Find a controlling argument, if any 707 708 if Present (Parameter_Associations (N)) then 709 Subp_Entity := Entity (Name (N)); 710 711 Actual := First_Actual (N); 712 Formal := First_Formal (Subp_Entity); 713 while Present (Actual) loop 714 Control := Find_Controlling_Arg (Actual); 715 exit when Present (Control); 716 717 -- Check for the case where the actual is a tag-indeterminate call 718 -- whose result type is different than the tagged type associated 719 -- with the containing call, but is an ancestor of the type. 720 721 if Is_Controlling_Formal (Formal) 722 and then Is_Tag_Indeterminate (Actual) 723 and then Base_Type (Etype (Actual)) /= Base_Type (Etype (Formal)) 724 and then Is_Ancestor (Etype (Actual), Etype (Formal)) 725 then 726 Indeterm_Ancestor_Call := True; 727 Indeterm_Ctrl_Type := Etype (Formal); 728 729 -- If the formal is controlling but the actual is not, the type 730 -- of the actual is statically known, and may be used as the 731 -- controlling tag for some other tag-indeterminate actual. 732 733 elsif Is_Controlling_Formal (Formal) 734 and then Is_Entity_Name (Actual) 735 and then Is_Tagged_Type (Etype (Actual)) 736 then 737 Static_Tag := Actual; 738 end if; 739 740 Next_Actual (Actual); 741 Next_Formal (Formal); 742 end loop; 743 744 -- If the call doesn't have a controlling actual but does have an 745 -- indeterminate actual that requires dispatching treatment, then an 746 -- object is needed that will serve as the controlling argument for 747 -- a dispatching call on the indeterminate actual. This can occur 748 -- in the unusual situation of a default actual given by a tag- 749 -- indeterminate call and where the type of the call is an ancestor 750 -- of the type associated with a containing call to an inherited 751 -- operation (see AI-239). 752 753 -- Rather than create an object of the tagged type, which would 754 -- be problematic for various reasons (default initialization, 755 -- discriminants), the tag of the containing call's associated 756 -- tagged type is directly used to control the dispatching. 757 758 if No (Control) 759 and then Indeterm_Ancestor_Call 760 and then No (Static_Tag) 761 then 762 Control := 763 Make_Attribute_Reference (Loc, 764 Prefix => New_Occurrence_Of (Indeterm_Ctrl_Type, Loc), 765 Attribute_Name => Name_Tag); 766 767 Analyze (Control); 768 end if; 769 770 if Present (Control) then 771 772 -- Verify that no controlling arguments are statically tagged 773 774 if Debug_Flag_E then 775 Write_Str ("Found Dispatching call"); 776 Write_Int (Int (N)); 777 Write_Eol; 778 end if; 779 780 Actual := First_Actual (N); 781 while Present (Actual) loop 782 if Actual /= Control then 783 784 if not Is_Controlling_Actual (Actual) then 785 null; -- Can be anything 786 787 elsif Is_Dynamically_Tagged (Actual) then 788 null; -- Valid parameter 789 790 elsif Is_Tag_Indeterminate (Actual) then 791 792 -- The tag is inherited from the enclosing call (the node 793 -- we are currently analyzing). Explicitly expand the 794 -- actual, since the previous call to Expand (from 795 -- Resolve_Call) had no way of knowing about the 796 -- required dispatching. 797 798 Propagate_Tag (Control, Actual); 799 800 else 801 Error_Msg_N 802 ("controlling argument is not dynamically tagged", 803 Actual); 804 return; 805 end if; 806 end if; 807 808 Next_Actual (Actual); 809 end loop; 810 811 -- Mark call as a dispatching call 812 813 Set_Controlling_Argument (N, Control); 814 Check_Restriction (No_Dispatching_Calls, N); 815 816 -- The dispatching call may need to be converted into a direct 817 -- call in certain cases. 818 819 Check_Direct_Call; 820 821 -- If there is a statically tagged actual and a tag-indeterminate 822 -- call to a function of the ancestor (such as that provided by a 823 -- default), then treat this as a dispatching call and propagate 824 -- the tag to the tag-indeterminate call(s). 825 826 elsif Present (Static_Tag) and then Indeterm_Ancestor_Call then 827 Control := 828 Make_Attribute_Reference (Loc, 829 Prefix => 830 New_Occurrence_Of (Etype (Static_Tag), Loc), 831 Attribute_Name => Name_Tag); 832 833 Analyze (Control); 834 835 Actual := First_Actual (N); 836 Formal := First_Formal (Subp_Entity); 837 while Present (Actual) loop 838 if Is_Tag_Indeterminate (Actual) 839 and then Is_Controlling_Formal (Formal) 840 then 841 Propagate_Tag (Control, Actual); 842 end if; 843 844 Next_Actual (Actual); 845 Next_Formal (Formal); 846 end loop; 847 848 Check_Dispatching_Context (N); 849 850 elsif Nkind (N) /= N_Function_Call then 851 852 -- The call is not dispatching, so check that there aren't any 853 -- tag-indeterminate abstract calls left among its actuals. 854 855 Actual := First_Actual (N); 856 while Present (Actual) loop 857 if Is_Tag_Indeterminate (Actual) then 858 859 -- Function call case 860 861 if Nkind (Original_Node (Actual)) = N_Function_Call then 862 Func := Entity (Name (Original_Node (Actual))); 863 864 -- If the actual is an attribute then it can't be abstract 865 -- (the only current case of a tag-indeterminate attribute 866 -- is the stream Input attribute). 867 868 elsif Nkind (Original_Node (Actual)) = N_Attribute_Reference 869 then 870 Func := Empty; 871 872 -- Ditto if it is an explicit dereference 873 874 elsif Nkind (Original_Node (Actual)) = N_Explicit_Dereference 875 then 876 Func := Empty; 877 878 -- Only other possibility is a qualified expression whose 879 -- constituent expression is itself a call. 880 881 else 882 Func := 883 Entity (Name (Original_Node 884 (Expression (Original_Node (Actual))))); 885 end if; 886 887 if Present (Func) and then Is_Abstract_Subprogram (Func) then 888 Error_Msg_N 889 ("call to abstract function must be dispatching", 890 Actual); 891 end if; 892 end if; 893 894 Next_Actual (Actual); 895 end loop; 896 897 Check_Dispatching_Context (N); 898 return; 899 900 elsif Nkind (Parent (N)) in N_Subexpr then 901 Check_Dispatching_Context (N); 902 903 elsif Nkind (Parent (N)) = N_Assignment_Statement 904 and then Is_Class_Wide_Type (Etype (Name (Parent (N)))) 905 then 906 return; 907 908 elsif Is_Abstract_Subprogram (Subp_Entity) then 909 Check_Dispatching_Context (N); 910 return; 911 end if; 912 913 else 914 -- If dispatching on result, the enclosing call, if any, will 915 -- determine the controlling argument. Otherwise this is the 916 -- primitive operation of the root type. 917 918 Check_Dispatching_Context (N); 919 end if; 920 end Check_Dispatching_Call; 921 922 --------------------------------- 923 -- Check_Dispatching_Operation -- 924 --------------------------------- 925 926 procedure Check_Dispatching_Operation (Subp, Old_Subp : Entity_Id) is 927 procedure Warn_On_Late_Primitive_After_Private_Extension 928 (Typ : Entity_Id; 929 Prim : Entity_Id); 930 -- Prim is a dispatching primitive of the tagged type Typ. Warn on Prim 931 -- if it is a public primitive defined after some private extension of 932 -- the tagged type. 933 934 ---------------------------------------------------- 935 -- Warn_On_Late_Primitive_After_Private_Extension -- 936 ---------------------------------------------------- 937 938 procedure Warn_On_Late_Primitive_After_Private_Extension 939 (Typ : Entity_Id; 940 Prim : Entity_Id) 941 is 942 E : Entity_Id; 943 944 begin 945 if Warn_On_Late_Primitives 946 and then Comes_From_Source (Prim) 947 and then Has_Private_Extension (Typ) 948 and then Is_Package_Or_Generic_Package (Current_Scope) 949 and then not In_Private_Part (Current_Scope) 950 then 951 E := Next_Entity (Typ); 952 953 while E /= Prim loop 954 if Ekind (E) = E_Record_Type_With_Private 955 and then Etype (E) = Typ 956 then 957 Error_Msg_Name_1 := Chars (Typ); 958 Error_Msg_Name_2 := Chars (E); 959 Error_Msg_Sloc := Sloc (E); 960 Error_Msg_N 961 ("?j?primitive of type % defined after private extension " 962 & "% #?", Prim); 963 Error_Msg_Name_1 := Chars (Prim); 964 Error_Msg_Name_2 := Chars (E); 965 Error_Msg_N 966 ("\spec of % should appear before declaration of type %!", 967 Prim); 968 exit; 969 end if; 970 971 Next_Entity (E); 972 end loop; 973 end if; 974 end Warn_On_Late_Primitive_After_Private_Extension; 975 976 -- Local variables 977 978 Body_Is_Last_Primitive : Boolean := False; 979 Has_Dispatching_Parent : Boolean := False; 980 Ovr_Subp : Entity_Id := Empty; 981 Tagged_Type : Entity_Id; 982 983 -- Start of processing for Check_Dispatching_Operation 984 985 begin 986 if not Ekind_In (Subp, E_Function, E_Procedure) then 987 return; 988 989 -- The Default_Initial_Condition procedure is not a primitive subprogram 990 -- even if it relates to a tagged type. This routine is not meant to be 991 -- inherited or overridden. 992 993 elsif Is_DIC_Procedure (Subp) then 994 return; 995 996 -- The "partial" and "full" type invariant procedures are not primitive 997 -- subprograms even if they relate to a tagged type. These routines are 998 -- not meant to be inherited or overridden. 999 1000 elsif Is_Invariant_Procedure (Subp) 1001 or else Is_Partial_Invariant_Procedure (Subp) 1002 then 1003 return; 1004 end if; 1005 1006 Set_Is_Dispatching_Operation (Subp, False); 1007 Tagged_Type := Find_Dispatching_Type (Subp); 1008 1009 -- Ada 2005 (AI-345): Use the corresponding record (if available). 1010 -- Required because primitives of concurrent types are attached 1011 -- to the corresponding record (not to the concurrent type). 1012 1013 if Ada_Version >= Ada_2005 1014 and then Present (Tagged_Type) 1015 and then Is_Concurrent_Type (Tagged_Type) 1016 and then Present (Corresponding_Record_Type (Tagged_Type)) 1017 then 1018 Tagged_Type := Corresponding_Record_Type (Tagged_Type); 1019 end if; 1020 1021 -- (AI-345): The task body procedure is not a primitive of the tagged 1022 -- type 1023 1024 if Present (Tagged_Type) 1025 and then Is_Concurrent_Record_Type (Tagged_Type) 1026 and then Present (Corresponding_Concurrent_Type (Tagged_Type)) 1027 and then Is_Task_Type (Corresponding_Concurrent_Type (Tagged_Type)) 1028 and then Subp = Get_Task_Body_Procedure 1029 (Corresponding_Concurrent_Type (Tagged_Type)) 1030 then 1031 return; 1032 end if; 1033 1034 -- If Subp is derived from a dispatching operation then it should 1035 -- always be treated as dispatching. In this case various checks 1036 -- below will be bypassed. Makes sure that late declarations for 1037 -- inherited private subprograms are treated as dispatching, even 1038 -- if the associated tagged type is already frozen. 1039 1040 Has_Dispatching_Parent := 1041 Present (Alias (Subp)) 1042 and then Is_Dispatching_Operation (Alias (Subp)); 1043 1044 if No (Tagged_Type) then 1045 1046 -- Ada 2005 (AI-251): Check that Subp is not a primitive associated 1047 -- with an abstract interface type unless the interface acts as a 1048 -- parent type in a derivation. If the interface type is a formal 1049 -- type then the operation is not primitive and therefore legal. 1050 1051 declare 1052 E : Entity_Id; 1053 Typ : Entity_Id; 1054 1055 begin 1056 E := First_Entity (Subp); 1057 while Present (E) loop 1058 1059 -- For an access parameter, check designated type 1060 1061 if Ekind (Etype (E)) = E_Anonymous_Access_Type then 1062 Typ := Designated_Type (Etype (E)); 1063 else 1064 Typ := Etype (E); 1065 end if; 1066 1067 if Comes_From_Source (Subp) 1068 and then Is_Interface (Typ) 1069 and then not Is_Class_Wide_Type (Typ) 1070 and then not Is_Derived_Type (Typ) 1071 and then not Is_Generic_Type (Typ) 1072 and then not In_Instance 1073 then 1074 Error_Msg_N ("??declaration of& is too late!", Subp); 1075 Error_Msg_NE -- CODEFIX?? 1076 ("\??spec should appear immediately after declaration of " 1077 & "& !", Subp, Typ); 1078 exit; 1079 end if; 1080 1081 Next_Entity (E); 1082 end loop; 1083 1084 -- In case of functions check also the result type 1085 1086 if Ekind (Subp) = E_Function then 1087 if Is_Access_Type (Etype (Subp)) then 1088 Typ := Designated_Type (Etype (Subp)); 1089 else 1090 Typ := Etype (Subp); 1091 end if; 1092 1093 -- The following should be better commented, especially since 1094 -- we just added several new conditions here ??? 1095 1096 if Comes_From_Source (Subp) 1097 and then Is_Interface (Typ) 1098 and then not Is_Class_Wide_Type (Typ) 1099 and then not Is_Derived_Type (Typ) 1100 and then not Is_Generic_Type (Typ) 1101 and then not In_Instance 1102 then 1103 Error_Msg_N ("??declaration of& is too late!", Subp); 1104 Error_Msg_NE 1105 ("\??spec should appear immediately after declaration of " 1106 & "& !", Subp, Typ); 1107 end if; 1108 end if; 1109 end; 1110 1111 return; 1112 1113 -- The subprograms build internally after the freezing point (such as 1114 -- init procs, interface thunks, type support subprograms, and Offset 1115 -- to top functions for accessing interface components in variable 1116 -- size tagged types) are not primitives. 1117 1118 elsif Is_Frozen (Tagged_Type) 1119 and then not Comes_From_Source (Subp) 1120 and then not Has_Dispatching_Parent 1121 then 1122 -- Complete decoration of internally built subprograms that override 1123 -- a dispatching primitive. These entities correspond with the 1124 -- following cases: 1125 1126 -- 1. Ada 2005 (AI-391): Wrapper functions built by the expander 1127 -- to override functions of nonabstract null extensions. These 1128 -- primitives were added to the list of primitives of the tagged 1129 -- type by Make_Controlling_Function_Wrappers. However, attribute 1130 -- Is_Dispatching_Operation must be set to true. 1131 1132 -- 2. Ada 2005 (AI-251): Wrapper procedures of null interface 1133 -- primitives. 1134 1135 -- 3. Subprograms associated with stream attributes (built by 1136 -- New_Stream_Subprogram) 1137 1138 -- 4. Wrapper built for inherited operations with inherited class- 1139 -- wide conditions, where the conditions include calls to other 1140 -- overridden primitives. The wrappers include checks on these 1141 -- modified conditions. (AI12-113). 1142 1143 if Present (Old_Subp) 1144 and then Present (Overridden_Operation (Subp)) 1145 and then Is_Dispatching_Operation (Old_Subp) 1146 then 1147 pragma Assert 1148 ((Ekind (Subp) = E_Function 1149 and then Is_Dispatching_Operation (Old_Subp) 1150 and then Is_Null_Extension (Base_Type (Etype (Subp)))) 1151 1152 or else 1153 (Ekind (Subp) = E_Procedure 1154 and then Is_Dispatching_Operation (Old_Subp) 1155 and then Present (Alias (Old_Subp)) 1156 and then Is_Null_Interface_Primitive 1157 (Ultimate_Alias (Old_Subp))) 1158 1159 or else Get_TSS_Name (Subp) = TSS_Stream_Read 1160 or else Get_TSS_Name (Subp) = TSS_Stream_Write 1161 1162 or else Present (Contract (Overridden_Operation (Subp)))); 1163 1164 Check_Controlling_Formals (Tagged_Type, Subp); 1165 Override_Dispatching_Operation (Tagged_Type, Old_Subp, Subp); 1166 Set_Is_Dispatching_Operation (Subp); 1167 end if; 1168 1169 return; 1170 1171 -- The operation may be a child unit, whose scope is the defining 1172 -- package, but which is not a primitive operation of the type. 1173 1174 elsif Is_Child_Unit (Subp) then 1175 return; 1176 1177 -- If the subprogram is not defined in a package spec, the only case 1178 -- where it can be a dispatching op is when it overrides an operation 1179 -- before the freezing point of the type. 1180 1181 elsif ((not Is_Package_Or_Generic_Package (Scope (Subp))) 1182 or else In_Package_Body (Scope (Subp))) 1183 and then not Has_Dispatching_Parent 1184 then 1185 if not Comes_From_Source (Subp) 1186 or else (Present (Old_Subp) and then not Is_Frozen (Tagged_Type)) 1187 then 1188 null; 1189 1190 -- If the type is already frozen, the overriding is not allowed 1191 -- except when Old_Subp is not a dispatching operation (which can 1192 -- occur when Old_Subp was inherited by an untagged type). However, 1193 -- a body with no previous spec freezes the type *after* its 1194 -- declaration, and therefore is a legal overriding (unless the type 1195 -- has already been frozen). Only the first such body is legal. 1196 1197 elsif Present (Old_Subp) 1198 and then Is_Dispatching_Operation (Old_Subp) 1199 then 1200 if Comes_From_Source (Subp) 1201 and then 1202 (Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Body 1203 or else Nkind (Unit_Declaration_Node (Subp)) in N_Body_Stub) 1204 then 1205 declare 1206 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp); 1207 Decl_Item : Node_Id; 1208 1209 begin 1210 -- ??? The checks here for whether the type has been frozen 1211 -- prior to the new body are not complete. It's not simple 1212 -- to check frozenness at this point since the body has 1213 -- already caused the type to be prematurely frozen in 1214 -- Analyze_Declarations, but we're forced to recheck this 1215 -- here because of the odd rule interpretation that allows 1216 -- the overriding if the type wasn't frozen prior to the 1217 -- body. The freezing action should probably be delayed 1218 -- until after the spec is seen, but that's a tricky 1219 -- change to the delicate freezing code. 1220 1221 -- Look at each declaration following the type up until the 1222 -- new subprogram body. If any of the declarations is a body 1223 -- then the type has been frozen already so the overriding 1224 -- primitive is illegal. 1225 1226 Decl_Item := Next (Parent (Tagged_Type)); 1227 while Present (Decl_Item) 1228 and then (Decl_Item /= Subp_Body) 1229 loop 1230 if Comes_From_Source (Decl_Item) 1231 and then (Nkind (Decl_Item) in N_Proper_Body 1232 or else Nkind (Decl_Item) in N_Body_Stub) 1233 then 1234 Error_Msg_N ("overriding of& is too late!", Subp); 1235 Error_Msg_N 1236 ("\spec should appear immediately after the type!", 1237 Subp); 1238 exit; 1239 end if; 1240 1241 Next (Decl_Item); 1242 end loop; 1243 1244 -- If the subprogram doesn't follow in the list of 1245 -- declarations including the type then the type has 1246 -- definitely been frozen already and the body is illegal. 1247 1248 if No (Decl_Item) then 1249 Error_Msg_N ("overriding of& is too late!", Subp); 1250 Error_Msg_N 1251 ("\spec should appear immediately after the type!", 1252 Subp); 1253 1254 elsif Is_Frozen (Subp) then 1255 1256 -- The subprogram body declares a primitive operation. 1257 -- If the subprogram is already frozen, we must update 1258 -- its dispatching information explicitly here. The 1259 -- information is taken from the overridden subprogram. 1260 -- We must also generate a cross-reference entry because 1261 -- references to other primitives were already created 1262 -- when type was frozen. 1263 1264 Body_Is_Last_Primitive := True; 1265 1266 if Present (DTC_Entity (Old_Subp)) then 1267 Set_DTC_Entity (Subp, DTC_Entity (Old_Subp)); 1268 Set_DT_Position_Value (Subp, DT_Position (Old_Subp)); 1269 1270 if not Restriction_Active (No_Dispatching_Calls) then 1271 if Building_Static_DT (Tagged_Type) then 1272 1273 -- If the static dispatch table has not been 1274 -- built then there is nothing else to do now; 1275 -- otherwise we notify that we cannot build the 1276 -- static dispatch table. 1277 1278 if Has_Dispatch_Table (Tagged_Type) then 1279 Error_Msg_N 1280 ("overriding of& is too late for building " 1281 & " static dispatch tables!", Subp); 1282 Error_Msg_N 1283 ("\spec should appear immediately after " 1284 & "the type!", Subp); 1285 end if; 1286 1287 -- No code required to register primitives in VM 1288 -- targets 1289 1290 elsif not Tagged_Type_Expansion then 1291 null; 1292 1293 else 1294 Insert_Actions_After (Subp_Body, 1295 Register_Primitive (Sloc (Subp_Body), 1296 Prim => Subp)); 1297 end if; 1298 1299 -- Indicate that this is an overriding operation, 1300 -- and replace the overridden entry in the list of 1301 -- primitive operations, which is used for xref 1302 -- generation subsequently. 1303 1304 Generate_Reference (Tagged_Type, Subp, 'P', False); 1305 Override_Dispatching_Operation 1306 (Tagged_Type, Old_Subp, Subp); 1307 end if; 1308 end if; 1309 end if; 1310 end; 1311 1312 else 1313 Error_Msg_N ("overriding of& is too late!", Subp); 1314 Error_Msg_N 1315 ("\subprogram spec should appear immediately after the type!", 1316 Subp); 1317 end if; 1318 1319 -- If the type is not frozen yet and we are not in the overriding 1320 -- case it looks suspiciously like an attempt to define a primitive 1321 -- operation, which requires the declaration to be in a package spec 1322 -- (3.2.3(6)). Only report cases where the type and subprogram are 1323 -- in the same declaration list (by checking the enclosing parent 1324 -- declarations), to avoid spurious warnings on subprograms in 1325 -- instance bodies when the type is declared in the instance spec 1326 -- but hasn't been frozen by the instance body. 1327 1328 elsif not Is_Frozen (Tagged_Type) 1329 and then In_Same_List (Parent (Tagged_Type), Parent (Parent (Subp))) 1330 then 1331 Error_Msg_N 1332 ("??not dispatching (must be defined in a package spec)", Subp); 1333 return; 1334 1335 -- When the type is frozen, it is legitimate to define a new 1336 -- non-primitive operation. 1337 1338 else 1339 return; 1340 end if; 1341 1342 -- Now, we are sure that the scope is a package spec. If the subprogram 1343 -- is declared after the freezing point of the type that's an error 1344 1345 elsif Is_Frozen (Tagged_Type) and then not Has_Dispatching_Parent then 1346 Error_Msg_N ("this primitive operation is declared too late", Subp); 1347 Error_Msg_NE 1348 ("??no primitive operations for& after this line", 1349 Freeze_Node (Tagged_Type), 1350 Tagged_Type); 1351 return; 1352 end if; 1353 1354 Check_Controlling_Formals (Tagged_Type, Subp); 1355 1356 Ovr_Subp := Old_Subp; 1357 1358 -- [Ada 2012:AI-0125]: Search for inherited hidden primitive that may be 1359 -- overridden by Subp. This only applies to source subprograms, and 1360 -- their declaration must carry an explicit overriding indicator. 1361 1362 if No (Ovr_Subp) 1363 and then Ada_Version >= Ada_2012 1364 and then Comes_From_Source (Subp) 1365 and then 1366 Nkind (Unit_Declaration_Node (Subp)) = N_Subprogram_Declaration 1367 then 1368 Ovr_Subp := Find_Hidden_Overridden_Primitive (Subp); 1369 1370 -- Verify that the proper overriding indicator has been supplied. 1371 1372 if Present (Ovr_Subp) 1373 and then 1374 not Must_Override (Specification (Unit_Declaration_Node (Subp))) 1375 then 1376 Error_Msg_NE ("missing overriding indicator for&", Subp, Subp); 1377 end if; 1378 end if; 1379 1380 -- Now it should be a correct primitive operation, put it in the list 1381 1382 if Present (Ovr_Subp) then 1383 1384 -- If the type has interfaces we complete this check after we set 1385 -- attribute Is_Dispatching_Operation. 1386 1387 Check_Subtype_Conformant (Subp, Ovr_Subp); 1388 1389 -- A primitive operation with the name of a primitive controlled 1390 -- operation does not override a non-visible overriding controlled 1391 -- operation, i.e. one declared in a private part when the full 1392 -- view of a type is controlled. Conversely, it will override a 1393 -- visible operation that may be declared in a partial view when 1394 -- the full view is controlled. 1395 1396 if Nam_In (Chars (Subp), Name_Initialize, Name_Adjust, Name_Finalize) 1397 and then Is_Controlled (Tagged_Type) 1398 and then not Is_Visibly_Controlled (Tagged_Type) 1399 and then not Is_Inherited_Public_Operation (Ovr_Subp) 1400 then 1401 Set_Overridden_Operation (Subp, Empty); 1402 1403 -- If the subprogram specification carries an overriding 1404 -- indicator, no need for the warning: it is either redundant, 1405 -- or else an error will be reported. 1406 1407 if Nkind (Parent (Subp)) = N_Procedure_Specification 1408 and then 1409 (Must_Override (Parent (Subp)) 1410 or else Must_Not_Override (Parent (Subp))) 1411 then 1412 null; 1413 1414 -- Here we need the warning 1415 1416 else 1417 Error_Msg_NE 1418 ("operation does not override inherited&??", Subp, Subp); 1419 end if; 1420 1421 else 1422 Override_Dispatching_Operation (Tagged_Type, Ovr_Subp, Subp); 1423 1424 -- Ada 2005 (AI-251): In case of late overriding of a primitive 1425 -- that covers abstract interface subprograms we must register it 1426 -- in all the secondary dispatch tables associated with abstract 1427 -- interfaces. We do this now only if not building static tables, 1428 -- nor when the expander is inactive (we avoid trying to register 1429 -- primitives in semantics-only mode, since the type may not have 1430 -- an associated dispatch table). Otherwise the patch code is 1431 -- emitted after those tables are built, to prevent access before 1432 -- elaboration in gigi. 1433 1434 if Body_Is_Last_Primitive and then Expander_Active then 1435 declare 1436 Subp_Body : constant Node_Id := Unit_Declaration_Node (Subp); 1437 Elmt : Elmt_Id; 1438 Prim : Node_Id; 1439 1440 begin 1441 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 1442 while Present (Elmt) loop 1443 Prim := Node (Elmt); 1444 1445 -- No code required to register primitives in VM targets 1446 1447 if Present (Alias (Prim)) 1448 and then Present (Interface_Alias (Prim)) 1449 and then Alias (Prim) = Subp 1450 and then not Building_Static_DT (Tagged_Type) 1451 and then Tagged_Type_Expansion 1452 then 1453 Insert_Actions_After (Subp_Body, 1454 Register_Primitive (Sloc (Subp_Body), Prim => Prim)); 1455 end if; 1456 1457 Next_Elmt (Elmt); 1458 end loop; 1459 1460 -- Redisplay the contents of the updated dispatch table 1461 1462 if Debug_Flag_ZZ then 1463 Write_Str ("Late overriding: "); 1464 Write_DT (Tagged_Type); 1465 end if; 1466 end; 1467 end if; 1468 end if; 1469 1470 -- If the tagged type is a concurrent type then we must be compiling 1471 -- with no code generation (we are either compiling a generic unit or 1472 -- compiling under -gnatc mode) because we have previously tested that 1473 -- no serious errors has been reported. In this case we do not add the 1474 -- primitive to the list of primitives of Tagged_Type but we leave the 1475 -- primitive decorated as a dispatching operation to be able to analyze 1476 -- and report errors associated with the Object.Operation notation. 1477 1478 elsif Is_Concurrent_Type (Tagged_Type) then 1479 pragma Assert (not Expander_Active); 1480 1481 -- Attach operation to list of primitives of the synchronized type 1482 -- itself, for ASIS use. 1483 1484 Add_Dispatching_Operation (Tagged_Type, Subp); 1485 1486 -- If no old subprogram, then we add this as a dispatching operation, 1487 -- but we avoid doing this if an error was posted, to prevent annoying 1488 -- cascaded errors. 1489 1490 elsif not Error_Posted (Subp) then 1491 Add_Dispatching_Operation (Tagged_Type, Subp); 1492 end if; 1493 1494 Set_Is_Dispatching_Operation (Subp, True); 1495 1496 -- Ada 2005 (AI-251): If the type implements interfaces we must check 1497 -- subtype conformance against all the interfaces covered by this 1498 -- primitive. 1499 1500 if Present (Ovr_Subp) 1501 and then Has_Interfaces (Tagged_Type) 1502 then 1503 declare 1504 Ifaces_List : Elist_Id; 1505 Iface_Elmt : Elmt_Id; 1506 Iface_Prim_Elmt : Elmt_Id; 1507 Iface_Prim : Entity_Id; 1508 Ret_Typ : Entity_Id; 1509 1510 begin 1511 Collect_Interfaces (Tagged_Type, Ifaces_List); 1512 1513 Iface_Elmt := First_Elmt (Ifaces_List); 1514 while Present (Iface_Elmt) loop 1515 if not Is_Ancestor (Node (Iface_Elmt), Tagged_Type) then 1516 Iface_Prim_Elmt := 1517 First_Elmt (Primitive_Operations (Node (Iface_Elmt))); 1518 while Present (Iface_Prim_Elmt) loop 1519 Iface_Prim := Node (Iface_Prim_Elmt); 1520 1521 if Is_Interface_Conformant 1522 (Tagged_Type, Iface_Prim, Subp) 1523 then 1524 -- Handle procedures, functions whose return type 1525 -- matches, or functions not returning interfaces 1526 1527 if Ekind (Subp) = E_Procedure 1528 or else Etype (Iface_Prim) = Etype (Subp) 1529 or else not Is_Interface (Etype (Iface_Prim)) 1530 then 1531 Check_Subtype_Conformant 1532 (New_Id => Subp, 1533 Old_Id => Iface_Prim, 1534 Err_Loc => Subp, 1535 Skip_Controlling_Formals => True); 1536 1537 -- Handle functions returning interfaces 1538 1539 elsif Implements_Interface 1540 (Etype (Subp), Etype (Iface_Prim)) 1541 then 1542 -- Temporarily force both entities to return the 1543 -- same type. Required because Subtype_Conformant 1544 -- does not handle this case. 1545 1546 Ret_Typ := Etype (Iface_Prim); 1547 Set_Etype (Iface_Prim, Etype (Subp)); 1548 1549 Check_Subtype_Conformant 1550 (New_Id => Subp, 1551 Old_Id => Iface_Prim, 1552 Err_Loc => Subp, 1553 Skip_Controlling_Formals => True); 1554 1555 Set_Etype (Iface_Prim, Ret_Typ); 1556 end if; 1557 end if; 1558 1559 Next_Elmt (Iface_Prim_Elmt); 1560 end loop; 1561 end if; 1562 1563 Next_Elmt (Iface_Elmt); 1564 end loop; 1565 end; 1566 end if; 1567 1568 if not Body_Is_Last_Primitive then 1569 Set_DT_Position_Value (Subp, No_Uint); 1570 1571 elsif Has_Controlled_Component (Tagged_Type) 1572 and then Nam_In (Chars (Subp), Name_Initialize, 1573 Name_Adjust, 1574 Name_Finalize, 1575 Name_Finalize_Address) 1576 then 1577 declare 1578 F_Node : constant Node_Id := Freeze_Node (Tagged_Type); 1579 Decl : Node_Id; 1580 Old_P : Entity_Id; 1581 Old_Bod : Node_Id; 1582 Old_Spec : Entity_Id; 1583 1584 C_Names : constant array (1 .. 4) of Name_Id := 1585 (Name_Initialize, 1586 Name_Adjust, 1587 Name_Finalize, 1588 Name_Finalize_Address); 1589 1590 D_Names : constant array (1 .. 4) of TSS_Name_Type := 1591 (TSS_Deep_Initialize, 1592 TSS_Deep_Adjust, 1593 TSS_Deep_Finalize, 1594 TSS_Finalize_Address); 1595 1596 begin 1597 -- Remove previous controlled function which was constructed and 1598 -- analyzed when the type was frozen. This requires removing the 1599 -- body of the redefined primitive, as well as its specification 1600 -- if needed (there is no spec created for Deep_Initialize, see 1601 -- exp_ch3.adb). We must also dismantle the exception information 1602 -- that may have been generated for it when front end zero-cost 1603 -- tables are enabled. 1604 1605 for J in D_Names'Range loop 1606 Old_P := TSS (Tagged_Type, D_Names (J)); 1607 1608 if Present (Old_P) 1609 and then Chars (Subp) = C_Names (J) 1610 then 1611 Old_Bod := Unit_Declaration_Node (Old_P); 1612 Remove (Old_Bod); 1613 Set_Is_Eliminated (Old_P); 1614 Set_Scope (Old_P, Scope (Current_Scope)); 1615 1616 if Nkind (Old_Bod) = N_Subprogram_Body 1617 and then Present (Corresponding_Spec (Old_Bod)) 1618 then 1619 Old_Spec := Corresponding_Spec (Old_Bod); 1620 Set_Has_Completion (Old_Spec, False); 1621 end if; 1622 end if; 1623 end loop; 1624 1625 Build_Late_Proc (Tagged_Type, Chars (Subp)); 1626 1627 -- The new operation is added to the actions of the freeze node 1628 -- for the type, but this node has already been analyzed, so we 1629 -- must retrieve and analyze explicitly the new body. 1630 1631 if Present (F_Node) 1632 and then Present (Actions (F_Node)) 1633 then 1634 Decl := Last (Actions (F_Node)); 1635 Analyze (Decl); 1636 end if; 1637 end; 1638 end if; 1639 1640 -- For similarity with record extensions, in Ada 9X the language should 1641 -- have disallowed adding visible operations to a tagged type after 1642 -- deriving a private extension from it. Report a warning if this 1643 -- primitive is defined after a private extension of Tagged_Type. 1644 1645 Warn_On_Late_Primitive_After_Private_Extension (Tagged_Type, Subp); 1646 end Check_Dispatching_Operation; 1647 1648 ------------------------------------------ 1649 -- Check_Operation_From_Incomplete_Type -- 1650 ------------------------------------------ 1651 1652 procedure Check_Operation_From_Incomplete_Type 1653 (Subp : Entity_Id; 1654 Typ : Entity_Id) 1655 is 1656 Full : constant Entity_Id := Full_View (Typ); 1657 Parent_Typ : constant Entity_Id := Etype (Full); 1658 Old_Prim : constant Elist_Id := Primitive_Operations (Parent_Typ); 1659 New_Prim : constant Elist_Id := Primitive_Operations (Full); 1660 Op1, Op2 : Elmt_Id; 1661 Prev : Elmt_Id := No_Elmt; 1662 1663 function Derives_From (Parent_Subp : Entity_Id) return Boolean; 1664 -- Check that Subp has profile of an operation derived from Parent_Subp. 1665 -- Subp must have a parameter or result type that is Typ or an access 1666 -- parameter or access result type that designates Typ. 1667 1668 ------------------ 1669 -- Derives_From -- 1670 ------------------ 1671 1672 function Derives_From (Parent_Subp : Entity_Id) return Boolean is 1673 F1, F2 : Entity_Id; 1674 1675 begin 1676 if Chars (Parent_Subp) /= Chars (Subp) then 1677 return False; 1678 end if; 1679 1680 -- Check that the type of controlling formals is derived from the 1681 -- parent subprogram's controlling formal type (or designated type 1682 -- if the formal type is an anonymous access type). 1683 1684 F1 := First_Formal (Parent_Subp); 1685 F2 := First_Formal (Subp); 1686 while Present (F1) and then Present (F2) loop 1687 if Ekind (Etype (F1)) = E_Anonymous_Access_Type then 1688 if Ekind (Etype (F2)) /= E_Anonymous_Access_Type then 1689 return False; 1690 elsif Designated_Type (Etype (F1)) = Parent_Typ 1691 and then Designated_Type (Etype (F2)) /= Full 1692 then 1693 return False; 1694 end if; 1695 1696 elsif Ekind (Etype (F2)) = E_Anonymous_Access_Type then 1697 return False; 1698 1699 elsif Etype (F1) = Parent_Typ and then Etype (F2) /= Full then 1700 return False; 1701 end if; 1702 1703 Next_Formal (F1); 1704 Next_Formal (F2); 1705 end loop; 1706 1707 -- Check that a controlling result type is derived from the parent 1708 -- subprogram's result type (or designated type if the result type 1709 -- is an anonymous access type). 1710 1711 if Ekind (Parent_Subp) = E_Function then 1712 if Ekind (Subp) /= E_Function then 1713 return False; 1714 1715 elsif Ekind (Etype (Parent_Subp)) = E_Anonymous_Access_Type then 1716 if Ekind (Etype (Subp)) /= E_Anonymous_Access_Type then 1717 return False; 1718 1719 elsif Designated_Type (Etype (Parent_Subp)) = Parent_Typ 1720 and then Designated_Type (Etype (Subp)) /= Full 1721 then 1722 return False; 1723 end if; 1724 1725 elsif Ekind (Etype (Subp)) = E_Anonymous_Access_Type then 1726 return False; 1727 1728 elsif Etype (Parent_Subp) = Parent_Typ 1729 and then Etype (Subp) /= Full 1730 then 1731 return False; 1732 end if; 1733 1734 elsif Ekind (Subp) = E_Function then 1735 return False; 1736 end if; 1737 1738 return No (F1) and then No (F2); 1739 end Derives_From; 1740 1741 -- Start of processing for Check_Operation_From_Incomplete_Type 1742 1743 begin 1744 -- The operation may override an inherited one, or may be a new one 1745 -- altogether. The inherited operation will have been hidden by the 1746 -- current one at the point of the type derivation, so it does not 1747 -- appear in the list of primitive operations of the type. We have to 1748 -- find the proper place of insertion in the list of primitive opera- 1749 -- tions by iterating over the list for the parent type. 1750 1751 Op1 := First_Elmt (Old_Prim); 1752 Op2 := First_Elmt (New_Prim); 1753 while Present (Op1) and then Present (Op2) loop 1754 if Derives_From (Node (Op1)) then 1755 if No (Prev) then 1756 1757 -- Avoid adding it to the list of primitives if already there 1758 1759 if Node (Op2) /= Subp then 1760 Prepend_Elmt (Subp, New_Prim); 1761 end if; 1762 1763 else 1764 Insert_Elmt_After (Subp, Prev); 1765 end if; 1766 1767 return; 1768 end if; 1769 1770 Prev := Op2; 1771 Next_Elmt (Op1); 1772 Next_Elmt (Op2); 1773 end loop; 1774 1775 -- Operation is a new primitive 1776 1777 Append_Elmt (Subp, New_Prim); 1778 end Check_Operation_From_Incomplete_Type; 1779 1780 --------------------------------------- 1781 -- Check_Operation_From_Private_View -- 1782 --------------------------------------- 1783 1784 procedure Check_Operation_From_Private_View (Subp, Old_Subp : Entity_Id) is 1785 Tagged_Type : Entity_Id; 1786 1787 begin 1788 if Is_Dispatching_Operation (Alias (Subp)) then 1789 Set_Scope (Subp, Current_Scope); 1790 Tagged_Type := Find_Dispatching_Type (Subp); 1791 1792 -- Add Old_Subp to primitive operations if not already present 1793 1794 if Present (Tagged_Type) and then Is_Tagged_Type (Tagged_Type) then 1795 Add_Dispatching_Operation (Tagged_Type, Old_Subp); 1796 1797 -- If Old_Subp isn't already marked as dispatching then this is 1798 -- the case of an operation of an untagged private type fulfilled 1799 -- by a tagged type that overrides an inherited dispatching 1800 -- operation, so we set the necessary dispatching attributes here. 1801 1802 if not Is_Dispatching_Operation (Old_Subp) then 1803 1804 -- If the untagged type has no discriminants, and the full 1805 -- view is constrained, there will be a spurious mismatch of 1806 -- subtypes on the controlling arguments, because the tagged 1807 -- type is the internal base type introduced in the derivation. 1808 -- Use the original type to verify conformance, rather than the 1809 -- base type. 1810 1811 if not Comes_From_Source (Tagged_Type) 1812 and then Has_Discriminants (Tagged_Type) 1813 then 1814 declare 1815 Formal : Entity_Id; 1816 1817 begin 1818 Formal := First_Formal (Old_Subp); 1819 while Present (Formal) loop 1820 if Tagged_Type = Base_Type (Etype (Formal)) then 1821 Tagged_Type := Etype (Formal); 1822 end if; 1823 1824 Next_Formal (Formal); 1825 end loop; 1826 end; 1827 1828 if Tagged_Type = Base_Type (Etype (Old_Subp)) then 1829 Tagged_Type := Etype (Old_Subp); 1830 end if; 1831 end if; 1832 1833 Check_Controlling_Formals (Tagged_Type, Old_Subp); 1834 Set_Is_Dispatching_Operation (Old_Subp, True); 1835 Set_DT_Position_Value (Old_Subp, No_Uint); 1836 end if; 1837 1838 -- If the old subprogram is an explicit renaming of some other 1839 -- entity, it is not overridden by the inherited subprogram. 1840 -- Otherwise, update its alias and other attributes. 1841 1842 if Present (Alias (Old_Subp)) 1843 and then Nkind (Unit_Declaration_Node (Old_Subp)) /= 1844 N_Subprogram_Renaming_Declaration 1845 then 1846 Set_Alias (Old_Subp, Alias (Subp)); 1847 1848 -- The derived subprogram should inherit the abstractness of 1849 -- the parent subprogram (except in the case of a function 1850 -- returning the type). This sets the abstractness properly 1851 -- for cases where a private extension may have inherited an 1852 -- abstract operation, but the full type is derived from a 1853 -- descendant type and inherits a nonabstract version. 1854 1855 if Etype (Subp) /= Tagged_Type then 1856 Set_Is_Abstract_Subprogram 1857 (Old_Subp, Is_Abstract_Subprogram (Alias (Subp))); 1858 end if; 1859 end if; 1860 end if; 1861 end if; 1862 end Check_Operation_From_Private_View; 1863 1864 -------------------------- 1865 -- Find_Controlling_Arg -- 1866 -------------------------- 1867 1868 function Find_Controlling_Arg (N : Node_Id) return Node_Id is 1869 Orig_Node : constant Node_Id := Original_Node (N); 1870 Typ : Entity_Id; 1871 1872 begin 1873 if Nkind (Orig_Node) = N_Qualified_Expression then 1874 return Find_Controlling_Arg (Expression (Orig_Node)); 1875 end if; 1876 1877 -- Dispatching on result case. If expansion is disabled, the node still 1878 -- has the structure of a function call. However, if the function name 1879 -- is an operator and the call was given in infix form, the original 1880 -- node has no controlling result and we must examine the current node. 1881 1882 if Nkind (N) = N_Function_Call 1883 and then Present (Controlling_Argument (N)) 1884 and then Has_Controlling_Result (Entity (Name (N))) 1885 then 1886 return Controlling_Argument (N); 1887 1888 -- If expansion is enabled, the call may have been transformed into 1889 -- an indirect call, and we need to recover the original node. 1890 1891 elsif Nkind (Orig_Node) = N_Function_Call 1892 and then Present (Controlling_Argument (Orig_Node)) 1893 and then Has_Controlling_Result (Entity (Name (Orig_Node))) 1894 then 1895 return Controlling_Argument (Orig_Node); 1896 1897 -- Type conversions are dynamically tagged if the target type, or its 1898 -- designated type, are classwide. An interface conversion expands into 1899 -- a dereference, so test must be performed on the original node. 1900 1901 elsif Nkind (Orig_Node) = N_Type_Conversion 1902 and then Nkind (N) = N_Explicit_Dereference 1903 and then Is_Controlling_Actual (N) 1904 then 1905 declare 1906 Target_Type : constant Entity_Id := 1907 Entity (Subtype_Mark (Orig_Node)); 1908 1909 begin 1910 if Is_Class_Wide_Type (Target_Type) then 1911 return N; 1912 1913 elsif Is_Access_Type (Target_Type) 1914 and then Is_Class_Wide_Type (Designated_Type (Target_Type)) 1915 then 1916 return N; 1917 1918 else 1919 return Empty; 1920 end if; 1921 end; 1922 1923 -- Normal case 1924 1925 elsif Is_Controlling_Actual (N) 1926 or else 1927 (Nkind (Parent (N)) = N_Qualified_Expression 1928 and then Is_Controlling_Actual (Parent (N))) 1929 then 1930 Typ := Etype (N); 1931 1932 if Is_Access_Type (Typ) then 1933 1934 -- In the case of an Access attribute, use the type of the prefix, 1935 -- since in the case of an actual for an access parameter, the 1936 -- attribute's type may be of a specific designated type, even 1937 -- though the prefix type is class-wide. 1938 1939 if Nkind (N) = N_Attribute_Reference then 1940 Typ := Etype (Prefix (N)); 1941 1942 -- An allocator is dispatching if the type of qualified expression 1943 -- is class_wide, in which case this is the controlling type. 1944 1945 elsif Nkind (Orig_Node) = N_Allocator 1946 and then Nkind (Expression (Orig_Node)) = N_Qualified_Expression 1947 then 1948 Typ := Etype (Expression (Orig_Node)); 1949 else 1950 Typ := Designated_Type (Typ); 1951 end if; 1952 end if; 1953 1954 if Is_Class_Wide_Type (Typ) 1955 or else 1956 (Nkind (Parent (N)) = N_Qualified_Expression 1957 and then Is_Access_Type (Etype (N)) 1958 and then Is_Class_Wide_Type (Designated_Type (Etype (N)))) 1959 then 1960 return N; 1961 end if; 1962 end if; 1963 1964 return Empty; 1965 end Find_Controlling_Arg; 1966 1967 --------------------------- 1968 -- Find_Dispatching_Type -- 1969 --------------------------- 1970 1971 function Find_Dispatching_Type (Subp : Entity_Id) return Entity_Id is 1972 A_Formal : Entity_Id; 1973 Formal : Entity_Id; 1974 Ctrl_Type : Entity_Id; 1975 1976 begin 1977 if Ekind_In (Subp, E_Function, E_Procedure) 1978 and then Present (DTC_Entity (Subp)) 1979 then 1980 return Scope (DTC_Entity (Subp)); 1981 1982 -- For subprograms internally generated by derivations of tagged types 1983 -- use the alias subprogram as a reference to locate the dispatching 1984 -- type of Subp. 1985 1986 elsif not Comes_From_Source (Subp) 1987 and then Present (Alias (Subp)) 1988 and then Is_Dispatching_Operation (Alias (Subp)) 1989 then 1990 if Ekind (Alias (Subp)) = E_Function 1991 and then Has_Controlling_Result (Alias (Subp)) 1992 then 1993 return Check_Controlling_Type (Etype (Subp), Subp); 1994 1995 else 1996 Formal := First_Formal (Subp); 1997 A_Formal := First_Formal (Alias (Subp)); 1998 while Present (A_Formal) loop 1999 if Is_Controlling_Formal (A_Formal) then 2000 return Check_Controlling_Type (Etype (Formal), Subp); 2001 end if; 2002 2003 Next_Formal (Formal); 2004 Next_Formal (A_Formal); 2005 end loop; 2006 2007 pragma Assert (False); 2008 return Empty; 2009 end if; 2010 2011 -- General case 2012 2013 else 2014 Formal := First_Formal (Subp); 2015 while Present (Formal) loop 2016 Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp); 2017 2018 if Present (Ctrl_Type) then 2019 return Ctrl_Type; 2020 end if; 2021 2022 Next_Formal (Formal); 2023 end loop; 2024 2025 -- The subprogram may also be dispatching on result 2026 2027 if Present (Etype (Subp)) then 2028 return Check_Controlling_Type (Etype (Subp), Subp); 2029 end if; 2030 end if; 2031 2032 pragma Assert (not Is_Dispatching_Operation (Subp)); 2033 return Empty; 2034 end Find_Dispatching_Type; 2035 2036 -------------------------------------- 2037 -- Find_Hidden_Overridden_Primitive -- 2038 -------------------------------------- 2039 2040 function Find_Hidden_Overridden_Primitive (S : Entity_Id) return Entity_Id 2041 is 2042 Tag_Typ : constant Entity_Id := Find_Dispatching_Type (S); 2043 Elmt : Elmt_Id; 2044 Orig_Prim : Entity_Id; 2045 Prim : Entity_Id; 2046 Vis_List : Elist_Id; 2047 2048 begin 2049 -- This Ada 2012 rule applies only for type extensions or private 2050 -- extensions, where the parent type is not in a parent unit, and 2051 -- where an operation is never declared but still inherited. 2052 2053 if No (Tag_Typ) 2054 or else not Is_Record_Type (Tag_Typ) 2055 or else Etype (Tag_Typ) = Tag_Typ 2056 or else In_Open_Scopes (Scope (Etype (Tag_Typ))) 2057 then 2058 return Empty; 2059 end if; 2060 2061 -- Collect the list of visible ancestor of the tagged type 2062 2063 Vis_List := Visible_Ancestors (Tag_Typ); 2064 2065 Elmt := First_Elmt (Primitive_Operations (Tag_Typ)); 2066 while Present (Elmt) loop 2067 Prim := Node (Elmt); 2068 2069 -- Find an inherited hidden dispatching primitive with the name of S 2070 -- and a type-conformant profile. 2071 2072 if Present (Alias (Prim)) 2073 and then Is_Hidden (Alias (Prim)) 2074 and then Find_Dispatching_Type (Alias (Prim)) /= Tag_Typ 2075 and then Primitive_Names_Match (S, Prim) 2076 and then Type_Conformant (S, Prim) 2077 then 2078 declare 2079 Vis_Ancestor : Elmt_Id; 2080 Elmt : Elmt_Id; 2081 2082 begin 2083 -- The original corresponding operation of Prim must be an 2084 -- operation of a visible ancestor of the dispatching type S, 2085 -- and the original corresponding operation of S2 must be 2086 -- visible. 2087 2088 Orig_Prim := Original_Corresponding_Operation (Prim); 2089 2090 if Orig_Prim /= Prim 2091 and then Is_Immediately_Visible (Orig_Prim) 2092 then 2093 Vis_Ancestor := First_Elmt (Vis_List); 2094 while Present (Vis_Ancestor) loop 2095 Elmt := 2096 First_Elmt (Primitive_Operations (Node (Vis_Ancestor))); 2097 while Present (Elmt) loop 2098 if Node (Elmt) = Orig_Prim then 2099 Set_Overridden_Operation (S, Prim); 2100 Set_Alias (Prim, Orig_Prim); 2101 return Prim; 2102 end if; 2103 2104 Next_Elmt (Elmt); 2105 end loop; 2106 2107 Next_Elmt (Vis_Ancestor); 2108 end loop; 2109 end if; 2110 end; 2111 end if; 2112 2113 Next_Elmt (Elmt); 2114 end loop; 2115 2116 return Empty; 2117 end Find_Hidden_Overridden_Primitive; 2118 2119 --------------------------------------- 2120 -- Find_Primitive_Covering_Interface -- 2121 --------------------------------------- 2122 2123 function Find_Primitive_Covering_Interface 2124 (Tagged_Type : Entity_Id; 2125 Iface_Prim : Entity_Id) return Entity_Id 2126 is 2127 E : Entity_Id; 2128 El : Elmt_Id; 2129 2130 begin 2131 pragma Assert (Is_Interface (Find_Dispatching_Type (Iface_Prim)) 2132 or else (Present (Alias (Iface_Prim)) 2133 and then 2134 Is_Interface 2135 (Find_Dispatching_Type (Ultimate_Alias (Iface_Prim))))); 2136 2137 -- Search in the homonym chain. Done to speed up locating visible 2138 -- entities and required to catch primitives associated with the partial 2139 -- view of private types when processing the corresponding full view. 2140 2141 E := Current_Entity (Iface_Prim); 2142 while Present (E) loop 2143 if Is_Subprogram (E) 2144 and then Is_Dispatching_Operation (E) 2145 and then Is_Interface_Conformant (Tagged_Type, Iface_Prim, E) 2146 then 2147 return E; 2148 end if; 2149 2150 E := Homonym (E); 2151 end loop; 2152 2153 -- Search in the list of primitives of the type. Required to locate 2154 -- the covering primitive if the covering primitive is not visible 2155 -- (for example, non-visible inherited primitive of private type). 2156 2157 El := First_Elmt (Primitive_Operations (Tagged_Type)); 2158 while Present (El) loop 2159 E := Node (El); 2160 2161 -- Keep separate the management of internal entities that link 2162 -- primitives with interface primitives from tagged type primitives. 2163 2164 if No (Interface_Alias (E)) then 2165 if Present (Alias (E)) then 2166 2167 -- This interface primitive has not been covered yet 2168 2169 if Alias (E) = Iface_Prim then 2170 return E; 2171 2172 -- The covering primitive was inherited 2173 2174 elsif Overridden_Operation (Ultimate_Alias (E)) 2175 = Iface_Prim 2176 then 2177 return E; 2178 end if; 2179 end if; 2180 2181 -- Check if E covers the interface primitive (includes case in 2182 -- which E is an inherited private primitive). 2183 2184 if Is_Interface_Conformant (Tagged_Type, Iface_Prim, E) then 2185 return E; 2186 end if; 2187 2188 -- Use the internal entity that links the interface primitive with 2189 -- the covering primitive to locate the entity. 2190 2191 elsif Interface_Alias (E) = Iface_Prim then 2192 return Alias (E); 2193 end if; 2194 2195 Next_Elmt (El); 2196 end loop; 2197 2198 -- Not found 2199 2200 return Empty; 2201 end Find_Primitive_Covering_Interface; 2202 2203 --------------------------- 2204 -- Inheritance_Utilities -- 2205 --------------------------- 2206 2207 package body Inheritance_Utilities is 2208 2209 --------------------------- 2210 -- Inherited_Subprograms -- 2211 --------------------------- 2212 2213 function Inherited_Subprograms 2214 (S : Entity_Id; 2215 No_Interfaces : Boolean := False; 2216 Interfaces_Only : Boolean := False; 2217 One_Only : Boolean := False) return Subprogram_List 2218 is 2219 Result : Subprogram_List (1 .. 6000); 2220 -- 6000 here is intended to be infinity. We could use an expandable 2221 -- table, but it would be awfully heavy, and there is no way that we 2222 -- could reasonably exceed this value. 2223 2224 N : Nat := 0; 2225 -- Number of entries in Result 2226 2227 Parent_Op : Entity_Id; 2228 -- Traverses the Overridden_Operation chain 2229 2230 procedure Store_IS (E : Entity_Id); 2231 -- Stores E in Result if not already stored 2232 2233 -------------- 2234 -- Store_IS -- 2235 -------------- 2236 2237 procedure Store_IS (E : Entity_Id) is 2238 begin 2239 for J in 1 .. N loop 2240 if E = Result (J) then 2241 return; 2242 end if; 2243 end loop; 2244 2245 N := N + 1; 2246 Result (N) := E; 2247 end Store_IS; 2248 2249 -- Start of processing for Inherited_Subprograms 2250 2251 begin 2252 pragma Assert (not (No_Interfaces and Interfaces_Only)); 2253 2254 -- When used from backends, visibility can be handled differently 2255 -- resulting in no dispatching type being found. 2256 2257 if Present (S) 2258 and then Is_Dispatching_Operation (S) 2259 and then Present (Find_DT (S)) 2260 then 2261 -- Deal with direct inheritance 2262 2263 if not Interfaces_Only then 2264 Parent_Op := S; 2265 loop 2266 Parent_Op := Overridden_Operation (Parent_Op); 2267 exit when No (Parent_Op) 2268 or else (No_Interfaces 2269 and then Is_Interface (Find_DT (Parent_Op))); 2270 2271 if Is_Subprogram_Or_Generic_Subprogram (Parent_Op) then 2272 Store_IS (Parent_Op); 2273 2274 if One_Only then 2275 goto Done; 2276 end if; 2277 end if; 2278 end loop; 2279 end if; 2280 2281 -- Now deal with interfaces 2282 2283 if not No_Interfaces then 2284 declare 2285 Tag_Typ : Entity_Id; 2286 Prim : Entity_Id; 2287 Elmt : Elmt_Id; 2288 2289 begin 2290 Tag_Typ := Find_DT (S); 2291 2292 -- In the presence of limited views there may be no visible 2293 -- dispatching type. Primitives will be inherited when non- 2294 -- limited view is frozen. 2295 2296 if No (Tag_Typ) then 2297 return Result (1 .. 0); 2298 end if; 2299 2300 if Is_Concurrent_Type (Tag_Typ) then 2301 Tag_Typ := Corresponding_Record_Type (Tag_Typ); 2302 end if; 2303 2304 -- Search primitive operations of dispatching type 2305 2306 if Present (Tag_Typ) 2307 and then Present (Primitive_Operations (Tag_Typ)) 2308 then 2309 Elmt := First_Elmt (Primitive_Operations (Tag_Typ)); 2310 while Present (Elmt) loop 2311 Prim := Node (Elmt); 2312 2313 -- The following test eliminates some odd cases in 2314 -- which Ekind (Prim) is Void, to be investigated 2315 -- further ??? 2316 2317 if not Is_Subprogram_Or_Generic_Subprogram (Prim) then 2318 null; 2319 2320 -- For [generic] subprogram, look at interface 2321 -- alias. 2322 2323 elsif Present (Interface_Alias (Prim)) 2324 and then Alias (Prim) = S 2325 then 2326 -- We have found a primitive covered by S 2327 2328 Store_IS (Interface_Alias (Prim)); 2329 2330 if One_Only then 2331 goto Done; 2332 end if; 2333 end if; 2334 2335 Next_Elmt (Elmt); 2336 end loop; 2337 end if; 2338 end; 2339 end if; 2340 end if; 2341 2342 <<Done>> 2343 2344 return Result (1 .. N); 2345 end Inherited_Subprograms; 2346 2347 ------------------------------ 2348 -- Is_Overriding_Subprogram -- 2349 ------------------------------ 2350 2351 function Is_Overriding_Subprogram (E : Entity_Id) return Boolean is 2352 Inherited : constant Subprogram_List := 2353 Inherited_Subprograms (E, One_Only => True); 2354 begin 2355 return Inherited'Length > 0; 2356 end Is_Overriding_Subprogram; 2357 end Inheritance_Utilities; 2358 2359 -------------------------------- 2360 -- Inheritance_Utilities_Inst -- 2361 -------------------------------- 2362 2363 package Inheritance_Utilities_Inst is new 2364 Inheritance_Utilities (Find_Dispatching_Type); 2365 2366 --------------------------- 2367 -- Inherited_Subprograms -- 2368 --------------------------- 2369 2370 function Inherited_Subprograms 2371 (S : Entity_Id; 2372 No_Interfaces : Boolean := False; 2373 Interfaces_Only : Boolean := False; 2374 One_Only : Boolean := False) return Subprogram_List renames 2375 Inheritance_Utilities_Inst.Inherited_Subprograms; 2376 2377 --------------------------- 2378 -- Is_Dynamically_Tagged -- 2379 --------------------------- 2380 2381 function Is_Dynamically_Tagged (N : Node_Id) return Boolean is 2382 begin 2383 if Nkind (N) = N_Error then 2384 return False; 2385 2386 elsif Present (Find_Controlling_Arg (N)) then 2387 return True; 2388 2389 -- Special cases: entities, and calls that dispatch on result 2390 2391 elsif Is_Entity_Name (N) then 2392 return Is_Class_Wide_Type (Etype (N)); 2393 2394 elsif Nkind (N) = N_Function_Call 2395 and then Is_Class_Wide_Type (Etype (N)) 2396 then 2397 return True; 2398 2399 -- Otherwise check whether call has controlling argument 2400 2401 else 2402 return False; 2403 end if; 2404 end Is_Dynamically_Tagged; 2405 2406 --------------------------------- 2407 -- Is_Null_Interface_Primitive -- 2408 --------------------------------- 2409 2410 function Is_Null_Interface_Primitive (E : Entity_Id) return Boolean is 2411 begin 2412 return Comes_From_Source (E) 2413 and then Is_Dispatching_Operation (E) 2414 and then Ekind (E) = E_Procedure 2415 and then Null_Present (Parent (E)) 2416 and then Is_Interface (Find_Dispatching_Type (E)); 2417 end Is_Null_Interface_Primitive; 2418 2419 ----------------------------------- 2420 -- Is_Inherited_Public_Operation -- 2421 ----------------------------------- 2422 2423 function Is_Inherited_Public_Operation (Op : Entity_Id) return Boolean is 2424 Pack_Decl : Node_Id; 2425 Prim : Entity_Id := Op; 2426 Scop : Entity_Id := Prim; 2427 2428 begin 2429 -- Locate the ultimate non-hidden alias entity 2430 2431 while Present (Alias (Prim)) and then not Is_Hidden (Alias (Prim)) loop 2432 pragma Assert (Alias (Prim) /= Prim); 2433 Prim := Alias (Prim); 2434 Scop := Scope (Prim); 2435 end loop; 2436 2437 if Comes_From_Source (Prim) and then Ekind (Scop) = E_Package then 2438 Pack_Decl := Unit_Declaration_Node (Scop); 2439 2440 return 2441 Nkind (Pack_Decl) = N_Package_Declaration 2442 and then List_Containing (Unit_Declaration_Node (Prim)) = 2443 Visible_Declarations (Specification (Pack_Decl)); 2444 2445 else 2446 return False; 2447 end if; 2448 end Is_Inherited_Public_Operation; 2449 2450 ------------------------------ 2451 -- Is_Overriding_Subprogram -- 2452 ------------------------------ 2453 2454 function Is_Overriding_Subprogram (E : Entity_Id) return Boolean renames 2455 Inheritance_Utilities_Inst.Is_Overriding_Subprogram; 2456 2457 -------------------------- 2458 -- Is_Tag_Indeterminate -- 2459 -------------------------- 2460 2461 function Is_Tag_Indeterminate (N : Node_Id) return Boolean is 2462 Nam : Entity_Id; 2463 Actual : Node_Id; 2464 Orig_Node : constant Node_Id := Original_Node (N); 2465 2466 begin 2467 if Nkind (Orig_Node) = N_Function_Call 2468 and then Is_Entity_Name (Name (Orig_Node)) 2469 then 2470 Nam := Entity (Name (Orig_Node)); 2471 2472 if not Has_Controlling_Result (Nam) then 2473 return False; 2474 2475 -- The function may have a controlling result, but if the return type 2476 -- is not visibly tagged, then this is not tag-indeterminate. 2477 2478 elsif Is_Access_Type (Etype (Nam)) 2479 and then not Is_Tagged_Type (Designated_Type (Etype (Nam))) 2480 then 2481 return False; 2482 2483 -- An explicit dereference means that the call has already been 2484 -- expanded and there is no tag to propagate. 2485 2486 elsif Nkind (N) = N_Explicit_Dereference then 2487 return False; 2488 2489 -- If there are no actuals, the call is tag-indeterminate 2490 2491 elsif No (Parameter_Associations (Orig_Node)) then 2492 return True; 2493 2494 else 2495 Actual := First_Actual (Orig_Node); 2496 while Present (Actual) loop 2497 if Is_Controlling_Actual (Actual) 2498 and then not Is_Tag_Indeterminate (Actual) 2499 then 2500 -- One operand is dispatching 2501 2502 return False; 2503 end if; 2504 2505 Next_Actual (Actual); 2506 end loop; 2507 2508 return True; 2509 end if; 2510 2511 elsif Nkind (Orig_Node) = N_Qualified_Expression then 2512 return Is_Tag_Indeterminate (Expression (Orig_Node)); 2513 2514 -- Case of a call to the Input attribute (possibly rewritten), which is 2515 -- always tag-indeterminate except when its prefix is a Class attribute. 2516 2517 elsif Nkind (Orig_Node) = N_Attribute_Reference 2518 and then 2519 Get_Attribute_Id (Attribute_Name (Orig_Node)) = Attribute_Input 2520 and then Nkind (Prefix (Orig_Node)) /= N_Attribute_Reference 2521 then 2522 return True; 2523 2524 -- In Ada 2005, a function that returns an anonymous access type can be 2525 -- dispatching, and the dereference of a call to such a function can 2526 -- also be tag-indeterminate if the call itself is. 2527 2528 elsif Nkind (Orig_Node) = N_Explicit_Dereference 2529 and then Ada_Version >= Ada_2005 2530 then 2531 return Is_Tag_Indeterminate (Prefix (Orig_Node)); 2532 2533 else 2534 return False; 2535 end if; 2536 end Is_Tag_Indeterminate; 2537 2538 ------------------------------------ 2539 -- Override_Dispatching_Operation -- 2540 ------------------------------------ 2541 2542 procedure Override_Dispatching_Operation 2543 (Tagged_Type : Entity_Id; 2544 Prev_Op : Entity_Id; 2545 New_Op : Entity_Id; 2546 Is_Wrapper : Boolean := False) 2547 is 2548 Elmt : Elmt_Id; 2549 Prim : Node_Id; 2550 2551 begin 2552 -- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but 2553 -- we do it unconditionally in Ada 95 now, since this is our pragma). 2554 2555 if No_Return (Prev_Op) and then not No_Return (New_Op) then 2556 Error_Msg_N ("procedure & must have No_Return pragma", New_Op); 2557 Error_Msg_N ("\since overridden procedure has No_Return", New_Op); 2558 end if; 2559 2560 -- If there is no previous operation to override, the type declaration 2561 -- was malformed, and an error must have been emitted already. 2562 2563 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 2564 while Present (Elmt) and then Node (Elmt) /= Prev_Op loop 2565 Next_Elmt (Elmt); 2566 end loop; 2567 2568 if No (Elmt) then 2569 return; 2570 end if; 2571 2572 -- The location of entities that come from source in the list of 2573 -- primitives of the tagged type must follow their order of occurrence 2574 -- in the sources to fulfill the C++ ABI. If the overridden entity is a 2575 -- primitive of an interface that is not implemented by the parents of 2576 -- this tagged type (that is, it is an alias of an interface primitive 2577 -- generated by Derive_Interface_Progenitors), then we must append the 2578 -- new entity at the end of the list of primitives. 2579 2580 if Present (Alias (Prev_Op)) 2581 and then Etype (Tagged_Type) /= Tagged_Type 2582 and then Is_Interface (Find_Dispatching_Type (Alias (Prev_Op))) 2583 and then not Is_Ancestor (Find_Dispatching_Type (Alias (Prev_Op)), 2584 Tagged_Type, Use_Full_View => True) 2585 and then not Implements_Interface 2586 (Etype (Tagged_Type), 2587 Find_Dispatching_Type (Alias (Prev_Op))) 2588 then 2589 Remove_Elmt (Primitive_Operations (Tagged_Type), Elmt); 2590 Add_Dispatching_Operation (Tagged_Type, New_Op); 2591 2592 -- The new primitive replaces the overridden entity. Required to ensure 2593 -- that overriding primitive is assigned the same dispatch table slot. 2594 2595 else 2596 Replace_Elmt (Elmt, New_Op); 2597 end if; 2598 2599 if Ada_Version >= Ada_2005 and then Has_Interfaces (Tagged_Type) then 2600 2601 -- Ada 2005 (AI-251): Update the attribute alias of all the aliased 2602 -- entities of the overridden primitive to reference New_Op, and 2603 -- also propagate the proper value of Is_Abstract_Subprogram. Verify 2604 -- that the new operation is subtype conformant with the interface 2605 -- operations that it implements (for operations inherited from the 2606 -- parent itself, this check is made when building the derived type). 2607 2608 -- Note: This code is executed with internally generated wrappers of 2609 -- functions with controlling result and late overridings. 2610 2611 Elmt := First_Elmt (Primitive_Operations (Tagged_Type)); 2612 while Present (Elmt) loop 2613 Prim := Node (Elmt); 2614 2615 if Prim = New_Op then 2616 null; 2617 2618 -- Note: The check on Is_Subprogram protects the frontend against 2619 -- reading attributes in entities that are not yet fully decorated 2620 2621 elsif Is_Subprogram (Prim) 2622 and then Present (Interface_Alias (Prim)) 2623 and then Alias (Prim) = Prev_Op 2624 then 2625 Set_Alias (Prim, New_Op); 2626 2627 -- No further decoration needed yet for internally generated 2628 -- wrappers of controlling functions since (at this stage) 2629 -- they are not yet decorated. 2630 2631 if not Is_Wrapper then 2632 Check_Subtype_Conformant (New_Op, Prim); 2633 2634 Set_Is_Abstract_Subprogram (Prim, 2635 Is_Abstract_Subprogram (New_Op)); 2636 2637 -- Ensure that this entity will be expanded to fill the 2638 -- corresponding entry in its dispatch table. 2639 2640 if not Is_Abstract_Subprogram (Prim) then 2641 Set_Has_Delayed_Freeze (Prim); 2642 end if; 2643 end if; 2644 end if; 2645 2646 Next_Elmt (Elmt); 2647 end loop; 2648 end if; 2649 2650 if (not Is_Package_Or_Generic_Package (Current_Scope)) 2651 or else not In_Private_Part (Current_Scope) 2652 then 2653 -- Not a private primitive 2654 2655 null; 2656 2657 else pragma Assert (Is_Inherited_Operation (Prev_Op)); 2658 2659 -- Make the overriding operation into an alias of the implicit one. 2660 -- In this fashion a call from outside ends up calling the new body 2661 -- even if non-dispatching, and a call from inside calls the over- 2662 -- riding operation because it hides the implicit one. To indicate 2663 -- that the body of Prev_Op is never called, set its dispatch table 2664 -- entity to Empty. If the overridden operation has a dispatching 2665 -- result, so does the overriding one. 2666 2667 Set_Alias (Prev_Op, New_Op); 2668 Set_DTC_Entity (Prev_Op, Empty); 2669 Set_Has_Controlling_Result (New_Op, Has_Controlling_Result (Prev_Op)); 2670 return; 2671 end if; 2672 end Override_Dispatching_Operation; 2673 2674 ------------------- 2675 -- Propagate_Tag -- 2676 ------------------- 2677 2678 procedure Propagate_Tag (Control : Node_Id; Actual : Node_Id) is 2679 Call_Node : Node_Id; 2680 Arg : Node_Id; 2681 2682 begin 2683 if Nkind (Actual) = N_Function_Call then 2684 Call_Node := Actual; 2685 2686 elsif Nkind (Actual) = N_Identifier 2687 and then Nkind (Original_Node (Actual)) = N_Function_Call 2688 then 2689 -- Call rewritten as object declaration when stack-checking is 2690 -- enabled. Propagate tag to expression in declaration, which is 2691 -- original call. 2692 2693 Call_Node := Expression (Parent (Entity (Actual))); 2694 2695 -- Ada 2005: If this is a dereference of a call to a function with a 2696 -- dispatching access-result, the tag is propagated when the dereference 2697 -- itself is expanded (see exp_ch6.adb) and there is nothing else to do. 2698 2699 elsif Nkind (Actual) = N_Explicit_Dereference 2700 and then Nkind (Original_Node (Prefix (Actual))) = N_Function_Call 2701 then 2702 return; 2703 2704 -- When expansion is suppressed, an unexpanded call to 'Input can occur, 2705 -- and in that case we can simply return. 2706 2707 elsif Nkind (Actual) = N_Attribute_Reference then 2708 pragma Assert (Attribute_Name (Actual) = Name_Input); 2709 2710 return; 2711 2712 -- Only other possibilities are parenthesized or qualified expression, 2713 -- or an expander-generated unchecked conversion of a function call to 2714 -- a stream Input attribute. 2715 2716 else 2717 Call_Node := Expression (Actual); 2718 end if; 2719 2720 -- No action needed if the call has been already expanded 2721 2722 if Is_Expanded_Dispatching_Call (Call_Node) then 2723 return; 2724 end if; 2725 2726 -- Do not set the Controlling_Argument if already set. This happens in 2727 -- the special case of _Input (see Exp_Attr, case Input). 2728 2729 if No (Controlling_Argument (Call_Node)) then 2730 Set_Controlling_Argument (Call_Node, Control); 2731 end if; 2732 2733 Arg := First_Actual (Call_Node); 2734 while Present (Arg) loop 2735 if Is_Tag_Indeterminate (Arg) then 2736 Propagate_Tag (Control, Arg); 2737 end if; 2738 2739 Next_Actual (Arg); 2740 end loop; 2741 2742 -- Expansion of dispatching calls is suppressed on VM targets, because 2743 -- the VM back-ends directly handle the generation of dispatching calls 2744 -- and would have to undo any expansion to an indirect call. 2745 2746 if Tagged_Type_Expansion then 2747 declare 2748 Call_Typ : constant Entity_Id := Etype (Call_Node); 2749 2750 begin 2751 Expand_Dispatching_Call (Call_Node); 2752 2753 -- If the controlling argument is an interface type and the type 2754 -- of Call_Node differs then we must add an implicit conversion to 2755 -- force displacement of the pointer to the object to reference 2756 -- the secondary dispatch table of the interface. 2757 2758 if Is_Interface (Etype (Control)) 2759 and then Etype (Control) /= Call_Typ 2760 then 2761 -- Cannot use Convert_To because the previous call to 2762 -- Expand_Dispatching_Call leaves decorated the Call_Node 2763 -- with the type of Control. 2764 2765 Rewrite (Call_Node, 2766 Make_Type_Conversion (Sloc (Call_Node), 2767 Subtype_Mark => 2768 New_Occurrence_Of (Etype (Control), Sloc (Call_Node)), 2769 Expression => Relocate_Node (Call_Node))); 2770 Set_Etype (Call_Node, Etype (Control)); 2771 Set_Analyzed (Call_Node); 2772 2773 Expand_Interface_Conversion (Call_Node); 2774 end if; 2775 end; 2776 2777 -- Expansion of a dispatching call results in an indirect call, which in 2778 -- turn causes current values to be killed (see Resolve_Call), so on VM 2779 -- targets we do the call here to ensure consistent warnings between VM 2780 -- and non-VM targets. 2781 2782 else 2783 Kill_Current_Values; 2784 end if; 2785 end Propagate_Tag; 2786 2787end Sem_Disp; 2788