1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ W A R N -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1999-2013, 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 Einfo; use Einfo; 29with Errout; use Errout; 30with Exp_Code; use Exp_Code; 31with Fname; use Fname; 32with Lib; use Lib; 33with Lib.Xref; use Lib.Xref; 34with Namet; use Namet; 35with Nlists; use Nlists; 36with Opt; use Opt; 37with Par_SCO; use Par_SCO; 38with Rtsfind; use Rtsfind; 39with Sem; use Sem; 40with Sem_Ch8; use Sem_Ch8; 41with Sem_Aux; use Sem_Aux; 42with Sem_Eval; use Sem_Eval; 43with Sem_Util; use Sem_Util; 44with Sinfo; use Sinfo; 45with Sinput; use Sinput; 46with Snames; use Snames; 47with Stand; use Stand; 48with Stringt; use Stringt; 49with Uintp; use Uintp; 50 51package body Sem_Warn is 52 53 -- The following table collects Id's of entities that are potentially 54 -- unreferenced. See Check_Unset_Reference for further details. 55 -- ??? Check_Unset_Reference has zero information about this table. 56 57 package Unreferenced_Entities is new Table.Table ( 58 Table_Component_Type => Entity_Id, 59 Table_Index_Type => Nat, 60 Table_Low_Bound => 1, 61 Table_Initial => Alloc.Unreferenced_Entities_Initial, 62 Table_Increment => Alloc.Unreferenced_Entities_Increment, 63 Table_Name => "Unreferenced_Entities"); 64 65 -- The following table collects potential warnings for IN OUT parameters 66 -- that are referenced but not modified. These warnings are processed when 67 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings. 68 -- The reason that we defer output of these messages is that we want to 69 -- detect the case where the relevant procedure is used as a generic actual 70 -- in an instantiation, since we suppress the warnings in this case. The 71 -- flag Used_As_Generic_Actual will be set in this case, but only at the 72 -- point of usage. Similarly, we suppress the message if the address of the 73 -- procedure is taken, where the flag Address_Taken may be set later. 74 75 package In_Out_Warnings is new Table.Table ( 76 Table_Component_Type => Entity_Id, 77 Table_Index_Type => Nat, 78 Table_Low_Bound => 1, 79 Table_Initial => Alloc.In_Out_Warnings_Initial, 80 Table_Increment => Alloc.In_Out_Warnings_Increment, 81 Table_Name => "In_Out_Warnings"); 82 83 -------------------------------------------------------- 84 -- Handling of Warnings Off, Unmodified, Unreferenced -- 85 -------------------------------------------------------- 86 87 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must 88 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and 89 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo. 90 91 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary 92 -- warnings off pragma) mode, i.e. to avoid false negatives, the code 93 -- must follow some important rules. 94 95 -- Call these functions as late as possible, after completing all other 96 -- tests, just before the warnings is given. For example, don't write: 97 98 -- if not Has_Warnings_Off (E) 99 -- and then some-other-predicate-on-E then .. 100 101 -- Instead the following is preferred 102 103 -- if some-other-predicate-on-E 104 -- and then Has_Warnings_Off (E) 105 106 -- This way if some-other-predicate is false, we avoid a false indication 107 -- that a Warnings (Off, E) pragma was useful in preventing a warning. 108 109 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or 110 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the 111 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record 112 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In 113 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off, 114 -- and so a subsequent test is not needed anyway (though it is harmless). 115 116 ----------------------- 117 -- Local Subprograms -- 118 ----------------------- 119 120 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean; 121 -- This returns true if the entity E is declared within a generic package. 122 -- The point of this is to detect variables which are not assigned within 123 -- the generic, but might be assigned outside the package for any given 124 -- instance. These are cases where we leave the warnings to be posted for 125 -- the instance, when we will know more. 126 127 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id; 128 -- If E is a parameter entity for a subprogram body, then this function 129 -- returns the corresponding spec entity, if not, E is returned unchanged. 130 131 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean; 132 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal, 133 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is 134 -- a body formal, the setting of the flag in the corresponding spec is 135 -- also checked (and True returned if either flag is True). 136 137 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean; 138 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal, 139 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is 140 -- a body formal, the setting of the flag in the corresponding spec is 141 -- also checked (and True returned if either flag is True). 142 143 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean; 144 -- Tests Never_Set_In_Source status for entity E. If E is not a formal, 145 -- this is simply the setting of the flag Never_Set_In_Source. If E is 146 -- a body formal, the setting of the flag in the corresponding spec is 147 -- also checked (and False returned if either flag is False). 148 149 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean; 150 -- This function traverses the expression tree represented by the node N 151 -- and determines if any sub-operand is a reference to an entity for which 152 -- the Warnings_Off flag is set. True is returned if such an entity is 153 -- encountered, and False otherwise. 154 155 function Referenced_Check_Spec (E : Entity_Id) return Boolean; 156 -- Tests Referenced status for entity E. If E is not a formal, this is 157 -- simply the setting of the flag Referenced. If E is a body formal, the 158 -- setting of the flag in the corresponding spec is also checked (and True 159 -- returned if either flag is True). 160 161 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean; 162 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this 163 -- is simply the setting of the flag Referenced_As_LHS. If E is a body 164 -- formal, the setting of the flag in the corresponding spec is also 165 -- checked (and True returned if either flag is True). 166 167 function Referenced_As_Out_Parameter_Check_Spec 168 (E : Entity_Id) return Boolean; 169 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a 170 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E 171 -- is a body formal, the setting of the flag in the corresponding spec is 172 -- also checked (and True returned if either flag is True). 173 174 procedure Warn_On_Unreferenced_Entity 175 (Spec_E : Entity_Id; 176 Body_E : Entity_Id := Empty); 177 -- Output warnings for unreferenced entity E. For the case of an entry 178 -- formal, Body_E is the corresponding body entity for a particular 179 -- accept statement, and the message is posted on Body_E. In all other 180 -- cases, Body_E is ignored and must be Empty. 181 182 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean; 183 -- Returns True if Warnings_Off is set for the entity E or (in the case 184 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity. 185 186 -------------------------- 187 -- Check_Code_Statement -- 188 -------------------------- 189 190 procedure Check_Code_Statement (N : Node_Id) is 191 begin 192 -- If volatile, nothing to worry about 193 194 if Is_Asm_Volatile (N) then 195 return; 196 end if; 197 198 -- Warn if no input or no output 199 200 Setup_Asm_Inputs (N); 201 202 if No (Asm_Input_Value) then 203 Error_Msg_F 204 ("??code statement with no inputs should usually be Volatile!", N); 205 return; 206 end if; 207 208 Setup_Asm_Outputs (N); 209 210 if No (Asm_Output_Variable) then 211 Error_Msg_F 212 ("??code statement with no outputs should usually be Volatile!", N); 213 return; 214 end if; 215 end Check_Code_Statement; 216 217 --------------------------------- 218 -- Check_Infinite_Loop_Warning -- 219 --------------------------------- 220 221 -- The case we look for is a while loop which tests a local variable, where 222 -- there is no obvious direct or possible indirect update of the variable 223 -- within the body of the loop. 224 225 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is 226 Expression : Node_Id := Empty; 227 -- Set to WHILE or EXIT WHEN condition to be tested 228 229 Ref : Node_Id := Empty; 230 -- Reference in Expression to variable that might not be modified 231 -- in loop, indicating a possible infinite loop. 232 233 Var : Entity_Id := Empty; 234 -- Corresponding entity (entity of Ref) 235 236 Function_Call_Found : Boolean := False; 237 -- True if Find_Var found a function call in the condition 238 239 procedure Find_Var (N : Node_Id); 240 -- Inspect condition to see if it depends on a single entity reference. 241 -- If so, Ref is set to point to the reference node, and Var is set to 242 -- the referenced Entity. 243 244 function Has_Indirection (T : Entity_Id) return Boolean; 245 -- If the controlling variable is an access type, or is a record type 246 -- with access components, assume that it is changed indirectly and 247 -- suppress the warning. As a concession to low-level programming, in 248 -- particular within Declib, we also suppress warnings on a record 249 -- type that contains components of type Address or Short_Address. 250 251 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean; 252 -- Given an entity name, see if the name appears to have something to 253 -- do with I/O or network stuff, and if so, return True. Used to kill 254 -- some false positives on a heuristic basis that such functions will 255 -- likely have some strange side effect dependencies. A rather funny 256 -- kludge, but warning messages are in the heuristics business. 257 258 function Test_Ref (N : Node_Id) return Traverse_Result; 259 -- Test for reference to variable in question. Returns Abandon if 260 -- matching reference found. Used in instantiation of No_Ref_Found. 261 262 function No_Ref_Found is new Traverse_Func (Test_Ref); 263 -- Function to traverse body of procedure. Returns Abandon if matching 264 -- reference found. 265 266 -------------- 267 -- Find_Var -- 268 -------------- 269 270 procedure Find_Var (N : Node_Id) is 271 begin 272 -- Condition is a direct variable reference 273 274 if Is_Entity_Name (N) then 275 Ref := N; 276 Var := Entity (Ref); 277 278 -- Case of condition is a comparison with compile time known value 279 280 elsif Nkind (N) in N_Op_Compare then 281 if Compile_Time_Known_Value (Right_Opnd (N)) then 282 Find_Var (Left_Opnd (N)); 283 284 elsif Compile_Time_Known_Value (Left_Opnd (N)) then 285 Find_Var (Right_Opnd (N)); 286 287 -- Ignore any other comparison 288 289 else 290 return; 291 end if; 292 293 -- If condition is a negation, check its operand 294 295 elsif Nkind (N) = N_Op_Not then 296 Find_Var (Right_Opnd (N)); 297 298 -- Case of condition is function call 299 300 elsif Nkind (N) = N_Function_Call then 301 302 Function_Call_Found := True; 303 304 -- Forget it if function name is not entity, who knows what 305 -- we might be calling? 306 307 if not Is_Entity_Name (Name (N)) then 308 return; 309 310 -- Forget it if function name is suspicious. A strange test 311 -- but warning generation is in the heuristics business. 312 313 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then 314 return; 315 316 -- Forget it if warnings are suppressed on function entity 317 318 elsif Has_Warnings_Off (Entity (Name (N))) then 319 return; 320 end if; 321 322 -- OK, see if we have one argument 323 324 declare 325 PA : constant List_Id := Parameter_Associations (N); 326 327 begin 328 -- One argument, so check the argument 329 330 if Present (PA) 331 and then List_Length (PA) = 1 332 then 333 if Nkind (First (PA)) = N_Parameter_Association then 334 Find_Var (Explicit_Actual_Parameter (First (PA))); 335 else 336 Find_Var (First (PA)); 337 end if; 338 339 -- Not one argument 340 341 else 342 return; 343 end if; 344 end; 345 346 -- Any other kind of node is not something we warn for 347 348 else 349 return; 350 end if; 351 end Find_Var; 352 353 --------------------- 354 -- Has_Indirection -- 355 --------------------- 356 357 function Has_Indirection (T : Entity_Id) return Boolean is 358 Comp : Entity_Id; 359 Rec : Entity_Id; 360 361 begin 362 if Is_Access_Type (T) then 363 return True; 364 365 elsif Is_Private_Type (T) 366 and then Present (Full_View (T)) 367 and then Is_Access_Type (Full_View (T)) 368 then 369 return True; 370 371 elsif Is_Record_Type (T) then 372 Rec := T; 373 374 elsif Is_Private_Type (T) 375 and then Present (Full_View (T)) 376 and then Is_Record_Type (Full_View (T)) 377 then 378 Rec := Full_View (T); 379 else 380 return False; 381 end if; 382 383 Comp := First_Component (Rec); 384 while Present (Comp) loop 385 if Is_Access_Type (Etype (Comp)) 386 or else Is_Descendent_Of_Address (Etype (Comp)) 387 then 388 return True; 389 end if; 390 391 Next_Component (Comp); 392 end loop; 393 394 return False; 395 end Has_Indirection; 396 397 --------------------------------- 398 -- Is_Suspicious_Function_Name -- 399 --------------------------------- 400 401 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is 402 S : Entity_Id; 403 404 function Substring_Present (S : String) return Boolean; 405 -- Returns True if name buffer has given string delimited by non- 406 -- alphabetic characters or by end of string. S is lower case. 407 408 ----------------------- 409 -- Substring_Present -- 410 ----------------------- 411 412 function Substring_Present (S : String) return Boolean is 413 Len : constant Natural := S'Length; 414 415 begin 416 for J in 1 .. Name_Len - (Len - 1) loop 417 if Name_Buffer (J .. J + (Len - 1)) = S 418 and then 419 (J = 1 420 or else Name_Buffer (J - 1) not in 'a' .. 'z') 421 and then 422 (J + Len > Name_Len 423 or else Name_Buffer (J + Len) not in 'a' .. 'z') 424 then 425 return True; 426 end if; 427 end loop; 428 429 return False; 430 end Substring_Present; 431 432 -- Start of processing for Is_Suspicious_Function_Name 433 434 begin 435 S := E; 436 while Present (S) and then S /= Standard_Standard loop 437 Get_Name_String (Chars (S)); 438 439 if Substring_Present ("io") 440 or else Substring_Present ("file") 441 or else Substring_Present ("network") 442 then 443 return True; 444 else 445 S := Scope (S); 446 end if; 447 end loop; 448 449 return False; 450 end Is_Suspicious_Function_Name; 451 452 -------------- 453 -- Test_Ref -- 454 -------------- 455 456 function Test_Ref (N : Node_Id) return Traverse_Result is 457 begin 458 -- Waste of time to look at the expression we are testing 459 460 if N = Expression then 461 return Skip; 462 463 -- Direct reference to variable in question 464 465 elsif Is_Entity_Name (N) 466 and then Present (Entity (N)) 467 and then Entity (N) = Var 468 then 469 -- If this is an lvalue, then definitely abandon, since 470 -- this could be a direct modification of the variable. 471 472 if May_Be_Lvalue (N) then 473 return Abandon; 474 end if; 475 476 -- If the condition contains a function call, we consider it may 477 -- be modified by side-effects from a procedure call. Otherwise, 478 -- we consider the condition may not be modified, although that 479 -- might happen if Variable is itself a by-reference parameter, 480 -- and the procedure called modifies the global object referred to 481 -- by Variable, but we actually prefer to issue a warning in this 482 -- odd case. Note that the case where the procedure called has 483 -- visibility over Variable is treated in another case below. 484 485 if Function_Call_Found then 486 declare 487 P : Node_Id; 488 489 begin 490 P := N; 491 loop 492 P := Parent (P); 493 exit when P = Loop_Statement; 494 495 -- Abandon if at procedure call, or something strange is 496 -- going on (perhaps a node with no parent that should 497 -- have one but does not?) As always, for a warning we 498 -- prefer to just abandon the warning than get into the 499 -- business of complaining about the tree structure here. 500 501 if No (P) 502 or else Nkind (P) = N_Procedure_Call_Statement 503 then 504 return Abandon; 505 end if; 506 end loop; 507 end; 508 end if; 509 510 -- Reference to variable renaming variable in question 511 512 elsif Is_Entity_Name (N) 513 and then Present (Entity (N)) 514 and then Ekind (Entity (N)) = E_Variable 515 and then Present (Renamed_Object (Entity (N))) 516 and then Is_Entity_Name (Renamed_Object (Entity (N))) 517 and then Entity (Renamed_Object (Entity (N))) = Var 518 and then May_Be_Lvalue (N) 519 then 520 return Abandon; 521 522 -- Call to subprogram 523 524 elsif Nkind (N) in N_Subprogram_Call then 525 526 -- If subprogram is within the scope of the entity we are dealing 527 -- with as the loop variable, then it could modify this parameter, 528 -- so we abandon in this case. In the case of a subprogram that is 529 -- not an entity we also abandon. The check for no entity being 530 -- present is a defense against previous errors. 531 532 if not Is_Entity_Name (Name (N)) 533 or else No (Entity (Name (N))) 534 or else Scope_Within (Entity (Name (N)), Scope (Var)) 535 then 536 return Abandon; 537 end if; 538 539 -- If any of the arguments are of type access to subprogram, then 540 -- we may have funny side effects, so no warning in this case. 541 542 declare 543 Actual : Node_Id; 544 begin 545 Actual := First_Actual (N); 546 while Present (Actual) loop 547 if Is_Access_Subprogram_Type (Etype (Actual)) then 548 return Abandon; 549 else 550 Next_Actual (Actual); 551 end if; 552 end loop; 553 end; 554 555 -- Declaration of the variable in question 556 557 elsif Nkind (N) = N_Object_Declaration 558 and then Defining_Identifier (N) = Var 559 then 560 return Abandon; 561 end if; 562 563 -- All OK, continue scan 564 565 return OK; 566 end Test_Ref; 567 568 -- Start of processing for Check_Infinite_Loop_Warning 569 570 begin 571 -- Skip processing if debug flag gnatd.w is set 572 573 if Debug_Flag_Dot_W then 574 return; 575 end if; 576 577 -- Deal with Iteration scheme present 578 579 declare 580 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement); 581 582 begin 583 if Present (Iter) then 584 585 -- While iteration 586 587 if Present (Condition (Iter)) then 588 589 -- Skip processing for while iteration with conditions actions, 590 -- since they make it too complicated to get the warning right. 591 592 if Present (Condition_Actions (Iter)) then 593 return; 594 end if; 595 596 -- Capture WHILE condition 597 598 Expression := Condition (Iter); 599 600 -- For iteration, do not process, since loop will always terminate 601 602 elsif Present (Loop_Parameter_Specification (Iter)) then 603 return; 604 end if; 605 end if; 606 end; 607 608 -- Check chain of EXIT statements, we only process loops that have a 609 -- single exit condition (either a single EXIT WHEN statement, or a 610 -- WHILE loop not containing any EXIT WHEN statements). 611 612 declare 613 Ident : constant Node_Id := Identifier (Loop_Statement); 614 Exit_Stmt : Node_Id; 615 616 begin 617 -- If we don't have a proper chain set, ignore call entirely. This 618 -- happens because of previous errors. 619 620 if No (Entity (Ident)) 621 or else Ekind (Entity (Ident)) /= E_Loop 622 then 623 Check_Error_Detected; 624 return; 625 end if; 626 627 -- Otherwise prepare to scan list of EXIT statements 628 629 Exit_Stmt := First_Exit_Statement (Entity (Ident)); 630 while Present (Exit_Stmt) loop 631 632 -- Check for EXIT WHEN 633 634 if Present (Condition (Exit_Stmt)) then 635 636 -- Quit processing if EXIT WHEN in WHILE loop, or more than 637 -- one EXIT WHEN statement present in the loop. 638 639 if Present (Expression) then 640 return; 641 642 -- Otherwise capture condition from EXIT WHEN statement 643 644 else 645 Expression := Condition (Exit_Stmt); 646 end if; 647 648 -- If an unconditional exit statement is the last statement in the 649 -- loop, assume that no warning is needed, without any attempt at 650 -- checking whether the exit is reachable. 651 652 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then 653 return; 654 end if; 655 656 Exit_Stmt := Next_Exit_Statement (Exit_Stmt); 657 end loop; 658 end; 659 660 -- Return if no condition to test 661 662 if No (Expression) then 663 return; 664 end if; 665 666 -- Initial conditions met, see if condition is of right form 667 668 Find_Var (Expression); 669 670 -- Nothing to do if local variable from source not found. If it's a 671 -- renaming, it is probably renaming something too complicated to deal 672 -- with here. 673 674 if No (Var) 675 or else Ekind (Var) /= E_Variable 676 or else Is_Library_Level_Entity (Var) 677 or else not Comes_From_Source (Var) 678 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration 679 then 680 return; 681 682 -- Nothing to do if there is some indirection involved (assume that the 683 -- designated variable might be modified in some way we don't see). 684 -- However, if no function call was found, then we don't care about 685 -- indirections, because the condition must be something like "while X 686 -- /= null loop", so we don't care if X.all is modified in the loop. 687 688 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then 689 return; 690 691 -- Same sort of thing for volatile variable, might be modified by 692 -- some other task or by the operating system in some way. 693 694 elsif Is_Volatile (Var) then 695 return; 696 end if; 697 698 -- Filter out case of original statement sequence starting with delay. 699 -- We assume this is a multi-tasking program and that the condition 700 -- is affected by other threads (some kind of busy wait). 701 702 declare 703 Fstm : constant Node_Id := 704 Original_Node (First (Statements (Loop_Statement))); 705 begin 706 if Nkind (Fstm) = N_Delay_Relative_Statement 707 or else Nkind (Fstm) = N_Delay_Until_Statement 708 then 709 return; 710 end if; 711 end; 712 713 -- We have a variable reference of the right form, now we scan the loop 714 -- body to see if it looks like it might not be modified 715 716 if No_Ref_Found (Loop_Statement) = OK then 717 Error_Msg_NE 718 ("??variable& is not modified in loop body!", Ref, Var); 719 Error_Msg_N 720 ("\??possible infinite loop!", Ref); 721 end if; 722 end Check_Infinite_Loop_Warning; 723 724 ---------------------------- 725 -- Check_Low_Bound_Tested -- 726 ---------------------------- 727 728 procedure Check_Low_Bound_Tested (Expr : Node_Id) is 729 begin 730 if Comes_From_Source (Expr) then 731 declare 732 L : constant Node_Id := Left_Opnd (Expr); 733 R : constant Node_Id := Right_Opnd (Expr); 734 begin 735 if Nkind (L) = N_Attribute_Reference 736 and then Attribute_Name (L) = Name_First 737 and then Is_Entity_Name (Prefix (L)) 738 and then Is_Formal (Entity (Prefix (L))) 739 then 740 Set_Low_Bound_Tested (Entity (Prefix (L))); 741 end if; 742 743 if Nkind (R) = N_Attribute_Reference 744 and then Attribute_Name (R) = Name_First 745 and then Is_Entity_Name (Prefix (R)) 746 and then Is_Formal (Entity (Prefix (R))) 747 then 748 Set_Low_Bound_Tested (Entity (Prefix (R))); 749 end if; 750 end; 751 end if; 752 end Check_Low_Bound_Tested; 753 754 ---------------------- 755 -- Check_References -- 756 ---------------------- 757 758 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is 759 E1 : Entity_Id; 760 E1T : Entity_Id; 761 UR : Node_Id; 762 763 function Body_Formal 764 (E : Entity_Id; 765 Accept_Statement : Node_Id) return Entity_Id; 766 -- For an entry formal entity from an entry declaration, find the 767 -- corresponding body formal from the given accept statement. 768 769 function Missing_Subunits return Boolean; 770 -- We suppress warnings when there are missing subunits, because this 771 -- may generate too many false positives: entities in a parent may only 772 -- be referenced in one of the subunits. We make an exception for 773 -- subunits that contain no other stubs. 774 775 procedure Output_Reference_Error (M : String); 776 -- Used to output an error message. Deals with posting the error on the 777 -- body formal in the accept case. 778 779 function Publicly_Referenceable (Ent : Entity_Id) return Boolean; 780 -- This is true if the entity in question is potentially referenceable 781 -- from another unit. This is true for entities in packages that are at 782 -- the library level. 783 784 function Warnings_Off_E1 return Boolean; 785 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T), 786 -- or for the base type of E1T. 787 788 ----------------- 789 -- Body_Formal -- 790 ----------------- 791 792 function Body_Formal 793 (E : Entity_Id; 794 Accept_Statement : Node_Id) return Entity_Id 795 is 796 Body_Param : Node_Id; 797 Body_E : Entity_Id; 798 799 begin 800 -- Loop to find matching parameter in accept statement 801 802 Body_Param := First (Parameter_Specifications (Accept_Statement)); 803 while Present (Body_Param) loop 804 Body_E := Defining_Identifier (Body_Param); 805 806 if Chars (Body_E) = Chars (E) then 807 return Body_E; 808 end if; 809 810 Next (Body_Param); 811 end loop; 812 813 -- Should never fall through, should always find a match 814 815 raise Program_Error; 816 end Body_Formal; 817 818 ---------------------- 819 -- Missing_Subunits -- 820 ---------------------- 821 822 function Missing_Subunits return Boolean is 823 D : Node_Id; 824 825 begin 826 if not Unloaded_Subunits then 827 828 -- Normal compilation, all subunits are present 829 830 return False; 831 832 elsif E /= Main_Unit_Entity then 833 834 -- No warnings on a stub that is not the main unit 835 836 return True; 837 838 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then 839 D := First (Declarations (Unit_Declaration_Node (E))); 840 while Present (D) loop 841 842 -- No warnings if the proper body contains nested stubs 843 844 if Nkind (D) in N_Body_Stub then 845 return True; 846 end if; 847 848 Next (D); 849 end loop; 850 851 return False; 852 853 else 854 -- Missing stubs elsewhere 855 856 return True; 857 end if; 858 end Missing_Subunits; 859 860 ---------------------------- 861 -- Output_Reference_Error -- 862 ---------------------------- 863 864 procedure Output_Reference_Error (M : String) is 865 begin 866 -- Never issue messages for internal names, nor for renamings 867 868 if Is_Internal_Name (Chars (E1)) 869 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration 870 then 871 return; 872 end if; 873 874 -- Don't output message for IN OUT formal unless we have the warning 875 -- flag specifically set. It is a bit odd to distinguish IN OUT 876 -- formals from other cases. This distinction is historical in 877 -- nature. Warnings for IN OUT formals were added fairly late. 878 879 if Ekind (E1) = E_In_Out_Parameter 880 and then not Check_Unreferenced_Formals 881 then 882 return; 883 end if; 884 885 -- Other than accept case, post error on defining identifier 886 887 if No (Anod) then 888 Error_Msg_N (M, E1); 889 890 -- Accept case, find body formal to post the message 891 892 else 893 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1); 894 895 end if; 896 end Output_Reference_Error; 897 898 ---------------------------- 899 -- Publicly_Referenceable -- 900 ---------------------------- 901 902 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is 903 P : Node_Id; 904 Prev : Node_Id; 905 906 begin 907 -- A formal parameter is never referenceable outside the body of its 908 -- subprogram or entry. 909 910 if Is_Formal (Ent) then 911 return False; 912 end if; 913 914 -- Examine parents to look for a library level package spec. But if 915 -- we find a body or block or other similar construct along the way, 916 -- we cannot be referenced. 917 918 Prev := Ent; 919 P := Parent (Ent); 920 loop 921 case Nkind (P) is 922 923 -- If we get to top of tree, then publicly referenceable 924 925 when N_Empty => 926 return True; 927 928 -- If we reach a generic package declaration, then always 929 -- consider this referenceable, since any instantiation will 930 -- have access to the entities in the generic package. Note 931 -- that the package itself may not be instantiated, but then 932 -- we will get a warning for the package entity. 933 934 -- Note that generic formal parameters are themselves not 935 -- publicly referenceable in an instance, and warnings on them 936 -- are useful. 937 938 when N_Generic_Package_Declaration => 939 return 940 not Is_List_Member (Prev) 941 or else List_Containing (Prev) 942 /= Generic_Formal_Declarations (P); 943 944 -- Similarly, the generic formals of a generic subprogram are 945 -- not accessible. 946 947 when N_Generic_Subprogram_Declaration => 948 if Is_List_Member (Prev) 949 and then List_Containing (Prev) = 950 Generic_Formal_Declarations (P) 951 then 952 return False; 953 else 954 P := Parent (P); 955 end if; 956 957 -- If we reach a subprogram body, entity is not referenceable 958 -- unless it is the defining entity of the body. This will 959 -- happen, e.g. when a function is an attribute renaming that 960 -- is rewritten as a body. 961 962 when N_Subprogram_Body => 963 if Ent /= Defining_Entity (P) then 964 return False; 965 else 966 P := Parent (P); 967 end if; 968 969 -- If we reach any other body, definitely not referenceable 970 971 when N_Package_Body | 972 N_Task_Body | 973 N_Entry_Body | 974 N_Protected_Body | 975 N_Block_Statement | 976 N_Subunit => 977 return False; 978 979 -- For all other cases, keep looking up tree 980 981 when others => 982 Prev := P; 983 P := Parent (P); 984 end case; 985 end loop; 986 end Publicly_Referenceable; 987 988 --------------------- 989 -- Warnings_Off_E1 -- 990 --------------------- 991 992 function Warnings_Off_E1 return Boolean is 993 begin 994 return Has_Warnings_Off (E1T) 995 or else Has_Warnings_Off (Base_Type (E1T)) 996 or else Warnings_Off_Check_Spec (E1); 997 end Warnings_Off_E1; 998 999 -- Start of processing for Check_References 1000 1001 begin 1002 Process_Deferred_References; 1003 1004 -- No messages if warnings are suppressed, or if we have detected any 1005 -- real errors so far (this last check avoids junk messages resulting 1006 -- from errors, e.g. a subunit that is not loaded). 1007 1008 if Warning_Mode = Suppress 1009 or else Serious_Errors_Detected /= 0 1010 then 1011 return; 1012 end if; 1013 1014 -- We also skip the messages if any subunits were not loaded (see 1015 -- comment in Sem_Ch10 to understand how this is set, and why it is 1016 -- necessary to suppress the warnings in this case). 1017 1018 if Missing_Subunits then 1019 return; 1020 end if; 1021 1022 -- Otherwise loop through entities, looking for suspicious stuff 1023 1024 E1 := First_Entity (E); 1025 while Present (E1) loop 1026 E1T := Etype (E1); 1027 1028 -- We are only interested in source entities. We also don't issue 1029 -- warnings within instances, since the proper place for such 1030 -- warnings is on the template when it is compiled. 1031 1032 if Comes_From_Source (E1) 1033 and then Instantiation_Location (Sloc (E1)) = No_Location 1034 then 1035 -- We are interested in variables and out/in-out parameters, but 1036 -- we exclude protected types, too complicated to worry about. 1037 1038 if Ekind (E1) = E_Variable 1039 or else 1040 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter) 1041 and then not Is_Protected_Type (Current_Scope)) 1042 then 1043 -- Case of an unassigned variable 1044 1045 -- First gather any Unset_Reference indication for E1. In the 1046 -- case of a parameter, it is the Spec_Entity that is relevant. 1047 1048 if Ekind (E1) = E_Out_Parameter 1049 and then Present (Spec_Entity (E1)) 1050 then 1051 UR := Unset_Reference (Spec_Entity (E1)); 1052 else 1053 UR := Unset_Reference (E1); 1054 end if; 1055 1056 -- Special processing for access types 1057 1058 if Present (UR) 1059 and then Is_Access_Type (E1T) 1060 then 1061 -- For access types, the only time we made a UR entry was 1062 -- for a dereference, and so we post the appropriate warning 1063 -- here (note that the dereference may not be explicit in 1064 -- the source, for example in the case of a dispatching call 1065 -- with an anonymous access controlling formal, or of an 1066 -- assignment of a pointer involving discriminant check on 1067 -- the designated object). 1068 1069 if not Warnings_Off_E1 then 1070 Error_Msg_NE ("??& may be null!", UR, E1); 1071 end if; 1072 1073 goto Continue; 1074 1075 -- Case of variable that could be a constant. Note that we 1076 -- never signal such messages for generic package entities, 1077 -- since a given instance could have modifications outside 1078 -- the package. 1079 1080 elsif Warn_On_Constant 1081 and then (Ekind (E1) = E_Variable 1082 and then Has_Initial_Value (E1)) 1083 and then Never_Set_In_Source_Check_Spec (E1) 1084 and then not Address_Taken (E1) 1085 and then not Generic_Package_Spec_Entity (E1) 1086 then 1087 -- A special case, if this variable is volatile and not 1088 -- imported, it is not helpful to tell the programmer 1089 -- to mark the variable as constant, since this would be 1090 -- illegal by virtue of RM C.6(13). 1091 1092 if (Is_Volatile (E1) or else Has_Volatile_Components (E1)) 1093 and then not Is_Imported (E1) 1094 then 1095 Error_Msg_N 1096 ("?k?& is not modified, volatile has no effect!", E1); 1097 1098 -- Another special case, Exception_Occurrence, this catches 1099 -- the case of exception choice (and a bit more too, but not 1100 -- worth doing more investigation here). 1101 1102 elsif Is_RTE (E1T, RE_Exception_Occurrence) then 1103 null; 1104 1105 -- Here we give the warning if referenced and no pragma 1106 -- Unreferenced or Unmodified is present. 1107 1108 else 1109 -- Variable case 1110 1111 if Ekind (E1) = E_Variable then 1112 if Referenced_Check_Spec (E1) 1113 and then not Has_Pragma_Unreferenced_Check_Spec (E1) 1114 and then not Has_Pragma_Unmodified_Check_Spec (E1) 1115 then 1116 if not Warnings_Off_E1 then 1117 Error_Msg_N -- CODEFIX 1118 ("?k?& is not modified, " 1119 & "could be declared constant!", 1120 E1); 1121 end if; 1122 end if; 1123 end if; 1124 end if; 1125 1126 -- Other cases of a variable or parameter never set in source 1127 1128 elsif Never_Set_In_Source_Check_Spec (E1) 1129 1130 -- No warning if warning for this case turned off 1131 1132 and then Warn_On_No_Value_Assigned 1133 1134 -- No warning if address taken somewhere 1135 1136 and then not Address_Taken (E1) 1137 1138 -- No warning if explicit initial value 1139 1140 and then not Has_Initial_Value (E1) 1141 1142 -- No warning for generic package spec entities, since we 1143 -- might set them in a child unit or something like that 1144 1145 and then not Generic_Package_Spec_Entity (E1) 1146 1147 -- No warning if fully initialized type, except that for 1148 -- this purpose we do not consider access types to qualify 1149 -- as fully initialized types (relying on an access type 1150 -- variable being null when it is never set is a bit odd). 1151 1152 -- Also we generate warning for an out parameter that is 1153 -- never referenced, since again it seems odd to rely on 1154 -- default initialization to set an out parameter value. 1155 1156 and then (Is_Access_Type (E1T) 1157 or else Ekind (E1) = E_Out_Parameter 1158 or else not Is_Fully_Initialized_Type (E1T)) 1159 then 1160 -- Do not output complaint about never being assigned a 1161 -- value if a pragma Unmodified applies to the variable 1162 -- we are examining, or if it is a parameter, if there is 1163 -- a pragma Unreferenced for the corresponding spec, or 1164 -- if the type is marked as having unreferenced objects. 1165 -- The last is a little peculiar, but better too few than 1166 -- too many warnings in this situation. 1167 1168 if Has_Pragma_Unreferenced_Objects (E1T) 1169 or else Has_Pragma_Unmodified_Check_Spec (E1) 1170 then 1171 null; 1172 1173 -- IN OUT parameter case where parameter is referenced. We 1174 -- separate this out, since this is the case where we delay 1175 -- output of the warning until more information is available 1176 -- (about use in an instantiation or address being taken). 1177 1178 elsif Ekind (E1) = E_In_Out_Parameter 1179 and then Referenced_Check_Spec (E1) 1180 then 1181 -- Suppress warning if private type, and the procedure 1182 -- has a separate declaration in a different unit. This 1183 -- is the case where the client of a package sees only 1184 -- the private type, and it may be quite reasonable 1185 -- for the logical view to be IN OUT, even if the 1186 -- implementation ends up using access types or some 1187 -- other method to achieve the local effect of a 1188 -- modification. On the other hand if the spec and body 1189 -- are in the same unit, we are in the package body and 1190 -- there we have less excuse for a junk IN OUT parameter. 1191 1192 if Has_Private_Declaration (E1T) 1193 and then Present (Spec_Entity (E1)) 1194 and then not In_Same_Source_Unit (E1, Spec_Entity (E1)) 1195 then 1196 null; 1197 1198 -- Suppress warning for any parameter of a dispatching 1199 -- operation, since it is quite reasonable to have an 1200 -- operation that is overridden, and for some subclasses 1201 -- needs the formal to be IN OUT and for others happens 1202 -- not to assign it. 1203 1204 elsif Is_Dispatching_Operation 1205 (Scope (Goto_Spec_Entity (E1))) 1206 then 1207 null; 1208 1209 -- Suppress warning if composite type contains any access 1210 -- component, since the logical effect of modifying a 1211 -- parameter may be achieved by modifying a referenced 1212 -- object. 1213 1214 elsif Is_Composite_Type (E1T) 1215 and then Has_Access_Values (E1T) 1216 then 1217 null; 1218 1219 -- Suppress warning on formals of an entry body. All 1220 -- references are attached to the formal in the entry 1221 -- declaration, which are marked Is_Entry_Formal. 1222 1223 elsif Ekind (Scope (E1)) = E_Entry 1224 and then not Is_Entry_Formal (E1) 1225 then 1226 null; 1227 1228 -- OK, looks like warning for an IN OUT parameter that 1229 -- could be IN makes sense, but we delay the output of 1230 -- the warning, pending possibly finding out later on 1231 -- that the associated subprogram is used as a generic 1232 -- actual, or its address/access is taken. In these two 1233 -- cases, we suppress the warning because the context may 1234 -- force use of IN OUT, even if in this particular case 1235 -- the formal is not modified. 1236 1237 else 1238 In_Out_Warnings.Append (E1); 1239 end if; 1240 1241 -- Other cases of formals 1242 1243 elsif Is_Formal (E1) then 1244 if not Is_Trivial_Subprogram (Scope (E1)) then 1245 if Referenced_Check_Spec (E1) then 1246 if not Has_Pragma_Unmodified_Check_Spec (E1) 1247 and then not Warnings_Off_E1 1248 then 1249 Output_Reference_Error 1250 ("?f?formal parameter& is read but " 1251 & "never assigned!"); 1252 end if; 1253 1254 elsif not Has_Pragma_Unreferenced_Check_Spec (E1) 1255 and then not Warnings_Off_E1 1256 then 1257 Output_Reference_Error 1258 ("?f?formal parameter& is not referenced!"); 1259 end if; 1260 end if; 1261 1262 -- Case of variable 1263 1264 else 1265 if Referenced (E1) then 1266 if not Has_Unmodified (E1) 1267 and then not Warnings_Off_E1 1268 and then not Is_Junk_Name (Chars (E1)) 1269 then 1270 Output_Reference_Error 1271 ("?v?variable& is read but never assigned!"); 1272 end if; 1273 1274 elsif not Has_Unreferenced (E1) 1275 and then not Warnings_Off_E1 1276 and then not Is_Junk_Name (Chars (E1)) 1277 then 1278 Output_Reference_Error -- CODEFIX 1279 ("?v?variable& is never read and never assigned!"); 1280 end if; 1281 1282 -- Deal with special case where this variable is hidden 1283 -- by a loop variable. 1284 1285 if Ekind (E1) = E_Variable 1286 and then Present (Hiding_Loop_Variable (E1)) 1287 and then not Warnings_Off_E1 1288 then 1289 Error_Msg_N 1290 ("?v?for loop implicitly declares loop variable!", 1291 Hiding_Loop_Variable (E1)); 1292 1293 Error_Msg_Sloc := Sloc (E1); 1294 Error_Msg_N 1295 ("\?v?declaration hides & declared#!", 1296 Hiding_Loop_Variable (E1)); 1297 end if; 1298 end if; 1299 1300 goto Continue; 1301 end if; 1302 1303 -- Check for unset reference 1304 1305 if Warn_On_No_Value_Assigned and then Present (UR) then 1306 1307 -- For other than access type, go back to original node to 1308 -- deal with case where original unset reference has been 1309 -- rewritten during expansion. 1310 1311 -- In some cases, the original node may be a type conversion 1312 -- or qualification, and in this case we want the object 1313 -- entity inside. 1314 1315 UR := Original_Node (UR); 1316 while Nkind (UR) = N_Type_Conversion 1317 or else Nkind (UR) = N_Qualified_Expression 1318 or else Nkind (UR) = N_Expression_With_Actions 1319 loop 1320 UR := Expression (UR); 1321 end loop; 1322 1323 -- Don't issue warning if appearing inside Initial_Condition 1324 -- pragma or aspect, since that expression is not evaluated 1325 -- at the point where it occurs in the source. 1326 1327 if In_Pragma_Expression (UR, Name_Initial_Condition) then 1328 goto Continue; 1329 end if; 1330 1331 -- Here we issue the warning, all checks completed 1332 1333 -- If we have a return statement, this was a case of an OUT 1334 -- parameter not being set at the time of the return. (Note: 1335 -- it can't be N_Extended_Return_Statement, because those 1336 -- are only for functions, and functions do not allow OUT 1337 -- parameters.) 1338 1339 if not Is_Trivial_Subprogram (Scope (E1)) then 1340 if Nkind (UR) = N_Simple_Return_Statement 1341 and then not Has_Pragma_Unmodified_Check_Spec (E1) 1342 then 1343 if not Warnings_Off_E1 then 1344 Error_Msg_NE 1345 ("?v?OUT parameter& not set before return", 1346 UR, E1); 1347 end if; 1348 1349 -- If the unset reference is a selected component 1350 -- prefix from source, mention the component as well. 1351 -- If the selected component comes from expansion, all 1352 -- we know is that the entity is not fully initialized 1353 -- at the point of the reference. Locate a random 1354 -- uninitialized component to get a better message. 1355 1356 elsif Nkind (Parent (UR)) = N_Selected_Component then 1357 Error_Msg_Node_2 := Selector_Name (Parent (UR)); 1358 1359 if not Comes_From_Source (Parent (UR)) then 1360 declare 1361 Comp : Entity_Id; 1362 1363 begin 1364 Comp := First_Entity (E1T); 1365 while Present (Comp) loop 1366 if Ekind (Comp) = E_Component 1367 and then Nkind (Parent (Comp)) = 1368 N_Component_Declaration 1369 and then No (Expression (Parent (Comp))) 1370 then 1371 Error_Msg_Node_2 := Comp; 1372 exit; 1373 end if; 1374 1375 Next_Entity (Comp); 1376 end loop; 1377 end; 1378 end if; 1379 1380 -- Issue proper warning. This is a case of referencing 1381 -- a variable before it has been explicitly assigned. 1382 -- For access types, UR was only set for dereferences, 1383 -- so the issue is that the value may be null. 1384 1385 if not Is_Trivial_Subprogram (Scope (E1)) then 1386 if not Warnings_Off_E1 then 1387 if Is_Access_Type (Etype (Parent (UR))) then 1388 Error_Msg_N ("?`&.&` may be null!", UR); 1389 else 1390 Error_Msg_N 1391 ("?`&.&` may be referenced before " 1392 & "it has a value!", UR); 1393 end if; 1394 end if; 1395 end if; 1396 -- All other cases of unset reference active 1397 1398 elsif not Warnings_Off_E1 then 1399 Error_Msg_N 1400 ("?& may be referenced before it has a value!", 1401 UR); 1402 end if; 1403 end if; 1404 1405 goto Continue; 1406 end if; 1407 end if; 1408 1409 -- Then check for unreferenced entities. Note that we are only 1410 -- interested in entities whose Referenced flag is not set. 1411 1412 if not Referenced_Check_Spec (E1) 1413 1414 -- If Referenced_As_LHS is set, then that's still interesting 1415 -- (potential "assigned but never read" case), but not if we 1416 -- have pragma Unreferenced, which cancels this warning. 1417 1418 and then (not Referenced_As_LHS_Check_Spec (E1) 1419 or else not Has_Unreferenced (E1)) 1420 1421 -- Check that warnings on unreferenced entities are enabled 1422 1423 and then 1424 ((Check_Unreferenced and then not Is_Formal (E1)) 1425 1426 -- Case of warning on unreferenced formal 1427 1428 or else 1429 (Check_Unreferenced_Formals and then Is_Formal (E1)) 1430 1431 -- Case of warning on unread variables modified by an 1432 -- assignment, or an OUT parameter if it is the only one. 1433 1434 or else 1435 (Warn_On_Modified_Unread 1436 and then Referenced_As_LHS_Check_Spec (E1)) 1437 1438 -- Case of warning on any unread OUT parameter (note 1439 -- such indications are only set if the appropriate 1440 -- warning options were set, so no need to recheck here.) 1441 1442 or else 1443 Referenced_As_Out_Parameter_Check_Spec (E1)) 1444 1445 -- All other entities, including local packages that cannot be 1446 -- referenced from elsewhere, including those declared within a 1447 -- package body. 1448 1449 and then (Is_Object (E1) 1450 or else 1451 Is_Type (E1) 1452 or else 1453 Ekind (E1) = E_Label 1454 or else 1455 Ekind (E1) = E_Exception 1456 or else 1457 Ekind (E1) = E_Named_Integer 1458 or else 1459 Ekind (E1) = E_Named_Real 1460 or else 1461 Is_Overloadable (E1) 1462 1463 -- Package case, if the main unit is a package spec 1464 -- or generic package spec, then there may be a 1465 -- corresponding body that references this package 1466 -- in some other file. Otherwise we can be sure 1467 -- that there is no other reference. 1468 1469 or else 1470 (Ekind (E1) = E_Package 1471 and then 1472 not Is_Package_Or_Generic_Package 1473 (Cunit_Entity (Current_Sem_Unit)))) 1474 1475 -- Exclude instantiations, since there is no reason why every 1476 -- entity in an instantiation should be referenced. 1477 1478 and then Instantiation_Location (Sloc (E1)) = No_Location 1479 1480 -- Exclude formal parameters from bodies if the corresponding 1481 -- spec entity has been referenced in the case where there is 1482 -- a separate spec. 1483 1484 and then not (Is_Formal (E1) 1485 and then Ekind (Scope (E1)) = E_Subprogram_Body 1486 and then Present (Spec_Entity (E1)) 1487 and then Referenced (Spec_Entity (E1))) 1488 1489 -- Consider private type referenced if full view is referenced. 1490 -- If there is not full view, this is a generic type on which 1491 -- warnings are also useful. 1492 1493 and then 1494 not (Is_Private_Type (E1) 1495 and then Present (Full_View (E1)) 1496 and then Referenced (Full_View (E1))) 1497 1498 -- Don't worry about full view, only about private type 1499 1500 and then not Has_Private_Declaration (E1) 1501 1502 -- Eliminate dispatching operations from consideration, we 1503 -- cannot tell if these are referenced or not in any easy 1504 -- manner (note this also catches Adjust/Finalize/Initialize). 1505 1506 and then not Is_Dispatching_Operation (E1) 1507 1508 -- Check entity that can be publicly referenced (we do not give 1509 -- messages for such entities, since there could be other 1510 -- units, not involved in this compilation, that contain 1511 -- relevant references. 1512 1513 and then not Publicly_Referenceable (E1) 1514 1515 -- Class wide types are marked as source entities, but they are 1516 -- not really source entities, and are always created, so we do 1517 -- not care if they are not referenced. 1518 1519 and then Ekind (E1) /= E_Class_Wide_Type 1520 1521 -- Objects other than parameters of task types are allowed to 1522 -- be non-referenced, since they start up tasks. 1523 1524 and then ((Ekind (E1) /= E_Variable 1525 and then Ekind (E1) /= E_Constant 1526 and then Ekind (E1) /= E_Component) 1527 or else not Is_Task_Type (E1T)) 1528 1529 -- For subunits, only place warnings on the main unit itself, 1530 -- since parent units are not completely compiled. 1531 1532 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit 1533 or else Get_Source_Unit (E1) = Main_Unit) 1534 1535 -- No warning on a return object, because these are often 1536 -- created with a single expression and an implicit return. 1537 -- If the object is a variable there will be a warning 1538 -- indicating that it could be declared constant. 1539 1540 and then not 1541 (Ekind (E1) = E_Constant and then Is_Return_Object (E1)) 1542 then 1543 -- Suppress warnings in internal units if not in -gnatg mode 1544 -- (these would be junk warnings for an applications program, 1545 -- since they refer to problems in internal units). 1546 1547 if GNAT_Mode 1548 or else not Is_Internal_File_Name 1549 (Unit_File_Name (Get_Source_Unit (E1))) 1550 then 1551 -- We do not immediately flag the error. This is because we 1552 -- have not expanded generic bodies yet, and they may have 1553 -- the missing reference. So instead we park the entity on a 1554 -- list, for later processing. However for the case of an 1555 -- accept statement we want to output messages now, since 1556 -- we know we already have all information at hand, and we 1557 -- also want to have separate warnings for each accept 1558 -- statement for the same entry. 1559 1560 if Present (Anod) then 1561 pragma Assert (Is_Formal (E1)); 1562 1563 -- The unreferenced entity is E1, but post the warning 1564 -- on the body entity for this accept statement. 1565 1566 if not Warnings_Off_E1 then 1567 Warn_On_Unreferenced_Entity 1568 (E1, Body_Formal (E1, Accept_Statement => Anod)); 1569 end if; 1570 1571 elsif not Warnings_Off_E1 then 1572 Unreferenced_Entities.Append (E1); 1573 end if; 1574 end if; 1575 1576 -- Generic units are referenced in the generic body, but if they 1577 -- are not public and never instantiated we want to force a 1578 -- warning on them. We treat them as redundant constructs to 1579 -- minimize noise. 1580 1581 elsif Is_Generic_Subprogram (E1) 1582 and then not Is_Instantiated (E1) 1583 and then not Publicly_Referenceable (E1) 1584 and then Instantiation_Depth (Sloc (E1)) = 0 1585 and then Warn_On_Redundant_Constructs 1586 then 1587 if not Warnings_Off_E1 then 1588 Unreferenced_Entities.Append (E1); 1589 1590 -- Force warning on entity 1591 1592 Set_Referenced (E1, False); 1593 end if; 1594 end if; 1595 end if; 1596 1597 -- Recurse into nested package or block. Do not recurse into a formal 1598 -- package, because the corresponding body is not analyzed. 1599 1600 <<Continue>> 1601 if (Is_Package_Or_Generic_Package (E1) 1602 and then Nkind (Parent (E1)) = N_Package_Specification 1603 and then 1604 Nkind (Original_Node (Unit_Declaration_Node (E1))) 1605 /= N_Formal_Package_Declaration) 1606 1607 or else Ekind (E1) = E_Block 1608 then 1609 Check_References (E1); 1610 end if; 1611 1612 Next_Entity (E1); 1613 end loop; 1614 end Check_References; 1615 1616 --------------------------- 1617 -- Check_Unset_Reference -- 1618 --------------------------- 1619 1620 procedure Check_Unset_Reference (N : Node_Id) is 1621 Typ : constant Entity_Id := Etype (N); 1622 1623 function Is_OK_Fully_Initialized return Boolean; 1624 -- This function returns true if the given node N is fully initialized 1625 -- so that the reference is safe as far as this routine is concerned. 1626 -- Safe generally means that the type of N is a fully initialized type. 1627 -- The one special case is that for access types, which are always fully 1628 -- initialized, we don't consider a dereference OK since it will surely 1629 -- be dereferencing a null value, which won't do. 1630 1631 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean; 1632 -- Used to test indexed or selected component or slice to see if the 1633 -- evaluation of the prefix depends on a dereference, and if so, returns 1634 -- True, in which case we always check the prefix, even if we know that 1635 -- the referenced component is initialized. Pref is the prefix to test. 1636 1637 ----------------------------- 1638 -- Is_OK_Fully_Initialized -- 1639 ----------------------------- 1640 1641 function Is_OK_Fully_Initialized return Boolean is 1642 begin 1643 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then 1644 return False; 1645 else 1646 return Is_Fully_Initialized_Type (Typ); 1647 end if; 1648 end Is_OK_Fully_Initialized; 1649 1650 ---------------------------- 1651 -- Prefix_Has_Dereference -- 1652 ---------------------------- 1653 1654 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is 1655 begin 1656 -- If prefix is of an access type, it certainly needs a dereference 1657 1658 if Is_Access_Type (Etype (Pref)) then 1659 return True; 1660 1661 -- If prefix is explicit dereference, that's a dereference for sure 1662 1663 elsif Nkind (Pref) = N_Explicit_Dereference then 1664 return True; 1665 1666 -- If prefix is itself a component reference or slice check prefix 1667 1668 elsif Nkind (Pref) = N_Slice 1669 or else Nkind (Pref) = N_Indexed_Component 1670 or else Nkind (Pref) = N_Selected_Component 1671 then 1672 return Prefix_Has_Dereference (Prefix (Pref)); 1673 1674 -- All other cases do not involve a dereference 1675 1676 else 1677 return False; 1678 end if; 1679 end Prefix_Has_Dereference; 1680 1681 -- Start of processing for Check_Unset_Reference 1682 1683 begin 1684 -- Nothing to do if warnings suppressed 1685 1686 if Warning_Mode = Suppress then 1687 return; 1688 end if; 1689 1690 -- Nothing to do for numeric or string literal. Do this test early to 1691 -- save time in a common case (it does not matter that we do not include 1692 -- character literal here, since that will be caught later on in the 1693 -- when others branch of the case statement). 1694 1695 if Nkind (N) in N_Numeric_Or_String_Literal then 1696 return; 1697 end if; 1698 1699 -- Ignore reference unless it comes from source. Almost always if we 1700 -- have a reference from generated code, it is bogus (e.g. calls to init 1701 -- procs to set default discriminant values). 1702 1703 if not Comes_From_Source (N) then 1704 return; 1705 end if; 1706 1707 -- Otherwise see what kind of node we have. If the entity already has an 1708 -- unset reference, it is not necessarily the earliest in the text, 1709 -- because resolution of the prefix of selected components is completed 1710 -- before the resolution of the selected component itself. As a result, 1711 -- given (R /= null and then R.X > 0), the occurrences of R are examined 1712 -- in right-to-left order. If there is already an unset reference, we 1713 -- check whether N is earlier before proceeding. 1714 1715 case Nkind (N) is 1716 1717 -- For identifier or expanded name, examine the entity involved 1718 1719 when N_Identifier | N_Expanded_Name => 1720 declare 1721 E : constant Entity_Id := Entity (N); 1722 1723 begin 1724 if (Ekind (E) = E_Variable 1725 or else 1726 Ekind (E) = E_Out_Parameter) 1727 and then Never_Set_In_Source_Check_Spec (E) 1728 and then not Has_Initial_Value (E) 1729 and then (No (Unset_Reference (E)) 1730 or else 1731 Earlier_In_Extended_Unit 1732 (Sloc (N), Sloc (Unset_Reference (E)))) 1733 and then not Has_Pragma_Unmodified_Check_Spec (E) 1734 and then not Warnings_Off_Check_Spec (E) 1735 then 1736 -- We may have an unset reference. The first test is whether 1737 -- this is an access to a discriminant of a record or a 1738 -- component with default initialization. Both of these 1739 -- cases can be ignored, since the actual object that is 1740 -- referenced is definitely initialized. Note that this 1741 -- covers the case of reading discriminants of an OUT 1742 -- parameter, which is OK even in Ada 83. 1743 1744 -- Note that we are only interested in a direct reference to 1745 -- a record component here. If the reference is through an 1746 -- access type, then the access object is being referenced, 1747 -- not the record, and still deserves an unset reference. 1748 1749 if Nkind (Parent (N)) = N_Selected_Component 1750 and not Is_Access_Type (Typ) 1751 then 1752 declare 1753 ES : constant Entity_Id := 1754 Entity (Selector_Name (Parent (N))); 1755 begin 1756 if Ekind (ES) = E_Discriminant 1757 or else 1758 (Present (Declaration_Node (ES)) 1759 and then 1760 Present (Expression (Declaration_Node (ES)))) 1761 then 1762 return; 1763 end if; 1764 end; 1765 end if; 1766 1767 -- Exclude fully initialized types 1768 1769 if Is_OK_Fully_Initialized then 1770 return; 1771 end if; 1772 1773 -- Here we have a potential unset reference. But before we 1774 -- get worried about it, we have to make sure that the 1775 -- entity declaration is in the same procedure as the 1776 -- reference, since if they are in separate procedures, then 1777 -- we have no idea about sequential execution. 1778 1779 -- The tests in the loop below catch all such cases, but do 1780 -- allow the reference to appear in a loop, block, or 1781 -- package spec that is nested within the declaring scope. 1782 -- As always, it is possible to construct cases where the 1783 -- warning is wrong, that is why it is a warning. 1784 1785 Potential_Unset_Reference : declare 1786 SR : Entity_Id; 1787 SE : constant Entity_Id := Scope (E); 1788 1789 function Within_Postcondition return Boolean; 1790 -- Returns True iff N is within a Postcondition, an 1791 -- Ensures component in a Test_Case, or a Contract_Cases. 1792 1793 -------------------------- 1794 -- Within_Postcondition -- 1795 -------------------------- 1796 1797 function Within_Postcondition return Boolean is 1798 Nod, P : Node_Id; 1799 1800 begin 1801 Nod := Parent (N); 1802 while Present (Nod) loop 1803 if Nkind (Nod) = N_Pragma 1804 and then Nam_In (Pragma_Name (Nod), 1805 Name_Postcondition, 1806 Name_Contract_Cases) 1807 then 1808 return True; 1809 1810 elsif Present (Parent (Nod)) then 1811 P := Parent (Nod); 1812 1813 if Nkind (P) = N_Pragma 1814 and then 1815 Pragma_Name (P) = Name_Test_Case 1816 and then 1817 Nod = Get_Ensures_From_CTC_Pragma (P) 1818 then 1819 return True; 1820 end if; 1821 end if; 1822 1823 Nod := Parent (Nod); 1824 end loop; 1825 1826 return False; 1827 end Within_Postcondition; 1828 1829 -- Start of processing for Potential_Unset_Reference 1830 1831 begin 1832 SR := Current_Scope; 1833 while SR /= SE loop 1834 if SR = Standard_Standard 1835 or else Is_Subprogram (SR) 1836 or else Is_Concurrent_Body (SR) 1837 or else Is_Concurrent_Type (SR) 1838 then 1839 return; 1840 end if; 1841 1842 SR := Scope (SR); 1843 end loop; 1844 1845 -- Case of reference has an access type. This is a 1846 -- special case since access types are always set to null 1847 -- so cannot be truly uninitialized, but we still want to 1848 -- warn about cases of obvious null dereference. 1849 1850 if Is_Access_Type (Typ) then 1851 Access_Type_Case : declare 1852 P : Node_Id; 1853 1854 function Process 1855 (N : Node_Id) return Traverse_Result; 1856 -- Process function for instantiation of Traverse 1857 -- below. Checks if N contains reference to E other 1858 -- than a dereference. 1859 1860 function Ref_In (Nod : Node_Id) return Boolean; 1861 -- Determines whether Nod contains a reference to 1862 -- the entity E that is not a dereference. 1863 1864 ------------- 1865 -- Process -- 1866 ------------- 1867 1868 function Process 1869 (N : Node_Id) return Traverse_Result 1870 is 1871 begin 1872 if Is_Entity_Name (N) 1873 and then Entity (N) = E 1874 and then not Is_Dereferenced (N) 1875 then 1876 return Abandon; 1877 else 1878 return OK; 1879 end if; 1880 end Process; 1881 1882 ------------ 1883 -- Ref_In -- 1884 ------------ 1885 1886 function Ref_In (Nod : Node_Id) return Boolean is 1887 function Traverse is new Traverse_Func (Process); 1888 begin 1889 return Traverse (Nod) = Abandon; 1890 end Ref_In; 1891 1892 -- Start of processing for Access_Type_Case 1893 1894 begin 1895 -- Don't bother if we are inside an instance, since 1896 -- the compilation of the generic template is where 1897 -- the warning should be issued. 1898 1899 if In_Instance then 1900 return; 1901 end if; 1902 1903 -- Don't bother if this is not the main unit. If we 1904 -- try to give this warning for with'ed units, we 1905 -- get some false positives, since we do not record 1906 -- references in other units. 1907 1908 if not In_Extended_Main_Source_Unit (E) 1909 or else 1910 not In_Extended_Main_Source_Unit (N) 1911 then 1912 return; 1913 end if; 1914 1915 -- We are only interested in dereferences 1916 1917 if not Is_Dereferenced (N) then 1918 return; 1919 end if; 1920 1921 -- One more check, don't bother with references 1922 -- that are inside conditional statements or WHILE 1923 -- loops if the condition references the entity in 1924 -- question. This avoids most false positives. 1925 1926 P := Parent (N); 1927 loop 1928 P := Parent (P); 1929 exit when No (P); 1930 1931 if (Nkind (P) = N_If_Statement 1932 or else 1933 Nkind (P) = N_Elsif_Part) 1934 and then Ref_In (Condition (P)) 1935 then 1936 return; 1937 1938 elsif Nkind (P) = N_Loop_Statement 1939 and then Present (Iteration_Scheme (P)) 1940 and then 1941 Ref_In (Condition (Iteration_Scheme (P))) 1942 then 1943 return; 1944 end if; 1945 end loop; 1946 end Access_Type_Case; 1947 end if; 1948 1949 -- One more check, don't bother if we are within a 1950 -- postcondition, since the expression occurs in a 1951 -- place unrelated to the actual test. 1952 1953 if not Within_Postcondition then 1954 1955 -- Here we definitely have a case for giving a warning 1956 -- for a reference to an unset value. But we don't 1957 -- give the warning now. Instead set Unset_Reference 1958 -- in the identifier involved. The reason for this is 1959 -- that if we find the variable is never ever assigned 1960 -- a value then that warning is more important and 1961 -- there is no point in giving the reference warning. 1962 1963 -- If this is an identifier, set the field directly 1964 1965 if Nkind (N) = N_Identifier then 1966 Set_Unset_Reference (E, N); 1967 1968 -- Otherwise it is an expanded name, so set the field 1969 -- of the actual identifier for the reference. 1970 1971 else 1972 Set_Unset_Reference (E, Selector_Name (N)); 1973 end if; 1974 end if; 1975 end Potential_Unset_Reference; 1976 end if; 1977 end; 1978 1979 -- Indexed component or slice 1980 1981 when N_Indexed_Component | N_Slice => 1982 1983 -- If prefix does not involve dereferencing an access type, then 1984 -- we know we are OK if the component type is fully initialized, 1985 -- since the component will have been set as part of the default 1986 -- initialization. 1987 1988 if not Prefix_Has_Dereference (Prefix (N)) 1989 and then Is_OK_Fully_Initialized 1990 then 1991 return; 1992 1993 -- Look at prefix in access type case, or if the component is not 1994 -- fully initialized. 1995 1996 else 1997 Check_Unset_Reference (Prefix (N)); 1998 end if; 1999 2000 -- Record component 2001 2002 when N_Selected_Component => 2003 declare 2004 Pref : constant Node_Id := Prefix (N); 2005 Ent : constant Entity_Id := Entity (Selector_Name (N)); 2006 2007 begin 2008 -- If prefix involves dereferencing an access type, always 2009 -- check the prefix, since the issue then is whether this 2010 -- access value is null. 2011 2012 if Prefix_Has_Dereference (Pref) then 2013 null; 2014 2015 -- Always go to prefix if no selector entity is set. Can this 2016 -- happen in the normal case? Not clear, but it definitely can 2017 -- happen in error cases. 2018 2019 elsif No (Ent) then 2020 null; 2021 2022 -- For a record component, check some cases where we have 2023 -- reasonable cause to consider that the component is known to 2024 -- be or probably is initialized. In this case, we don't care 2025 -- if the prefix itself was explicitly initialized. 2026 2027 -- Discriminants are always considered initialized 2028 2029 elsif Ekind (Ent) = E_Discriminant then 2030 return; 2031 2032 -- An explicitly initialized component is certainly initialized 2033 2034 elsif Nkind (Parent (Ent)) = N_Component_Declaration 2035 and then Present (Expression (Parent (Ent))) 2036 then 2037 return; 2038 2039 -- A fully initialized component is initialized 2040 2041 elsif Is_OK_Fully_Initialized then 2042 return; 2043 end if; 2044 2045 -- If none of those cases apply, check the record type prefix 2046 2047 Check_Unset_Reference (Pref); 2048 end; 2049 2050 -- For type conversions, qualifications, or expressions with actions, 2051 -- examine the expression. 2052 2053 when N_Type_Conversion | 2054 N_Qualified_Expression | 2055 N_Expression_With_Actions => 2056 Check_Unset_Reference (Expression (N)); 2057 2058 -- For explicit dereference, always check prefix, which will generate 2059 -- an unset reference (since this is a case of dereferencing null). 2060 2061 when N_Explicit_Dereference => 2062 Check_Unset_Reference (Prefix (N)); 2063 2064 -- All other cases are not cases of an unset reference 2065 2066 when others => 2067 null; 2068 2069 end case; 2070 end Check_Unset_Reference; 2071 2072 ------------------------ 2073 -- Check_Unused_Withs -- 2074 ------------------------ 2075 2076 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is 2077 Cnode : Node_Id; 2078 Item : Node_Id; 2079 Lunit : Node_Id; 2080 Ent : Entity_Id; 2081 2082 Munite : constant Entity_Id := Cunit_Entity (Main_Unit); 2083 -- This is needed for checking the special renaming case 2084 2085 procedure Check_One_Unit (Unit : Unit_Number_Type); 2086 -- Subsidiary procedure, performs checks for specified unit 2087 2088 -------------------- 2089 -- Check_One_Unit -- 2090 -------------------- 2091 2092 procedure Check_One_Unit (Unit : Unit_Number_Type) is 2093 Is_Visible_Renaming : Boolean := False; 2094 Pack : Entity_Id; 2095 2096 procedure Check_Inner_Package (Pack : Entity_Id); 2097 -- Pack is a package local to a unit in a with_clause. Both the unit 2098 -- and Pack are referenced. If none of the entities in Pack are 2099 -- referenced, then the only occurrence of Pack is in a USE clause 2100 -- or a pragma, and a warning is worthwhile as well. 2101 2102 function Check_System_Aux return Boolean; 2103 -- Before giving a warning on a with_clause for System, check whether 2104 -- a system extension is present. 2105 2106 function Find_Package_Renaming 2107 (P : Entity_Id; 2108 L : Entity_Id) return Entity_Id; 2109 -- The only reference to a context unit may be in a renaming 2110 -- declaration. If this renaming declares a visible entity, do not 2111 -- warn that the context clause could be moved to the body, because 2112 -- the renaming may be intended to re-export the unit. 2113 2114 function Has_Visible_Entities (P : Entity_Id) return Boolean; 2115 -- This function determines if a package has any visible entities. 2116 -- True is returned if there is at least one declared visible entity, 2117 -- otherwise False is returned (e.g. case of only pragmas present). 2118 2119 ------------------------- 2120 -- Check_Inner_Package -- 2121 ------------------------- 2122 2123 procedure Check_Inner_Package (Pack : Entity_Id) is 2124 E : Entity_Id; 2125 Un : constant Node_Id := Sinfo.Unit (Cnode); 2126 2127 function Check_Use_Clause (N : Node_Id) return Traverse_Result; 2128 -- If N is a use_clause for Pack, emit warning 2129 2130 procedure Check_Use_Clauses is new 2131 Traverse_Proc (Check_Use_Clause); 2132 2133 ---------------------- 2134 -- Check_Use_Clause -- 2135 ---------------------- 2136 2137 function Check_Use_Clause (N : Node_Id) return Traverse_Result is 2138 Nam : Node_Id; 2139 2140 begin 2141 if Nkind (N) = N_Use_Package_Clause then 2142 Nam := First (Names (N)); 2143 while Present (Nam) loop 2144 if Entity (Nam) = Pack then 2145 2146 -- Suppress message if any serious errors detected 2147 -- that turn off expansion, and thus result in false 2148 -- positives for this warning. 2149 2150 if Serious_Errors_Detected = 0 then 2151 Error_Msg_Qual_Level := 1; 2152 Error_Msg_NE -- CODEFIX 2153 ("?u?no entities of package& are referenced!", 2154 Nam, Pack); 2155 Error_Msg_Qual_Level := 0; 2156 end if; 2157 end if; 2158 2159 Next (Nam); 2160 end loop; 2161 end if; 2162 2163 return OK; 2164 end Check_Use_Clause; 2165 2166 -- Start of processing for Check_Inner_Package 2167 2168 begin 2169 E := First_Entity (Pack); 2170 while Present (E) loop 2171 if Referenced_Check_Spec (E) then 2172 return; 2173 end if; 2174 2175 Next_Entity (E); 2176 end loop; 2177 2178 -- No entities of the package are referenced. Check whether the 2179 -- reference to the package itself is a use clause, and if so 2180 -- place a warning on it. 2181 2182 Check_Use_Clauses (Un); 2183 end Check_Inner_Package; 2184 2185 ---------------------- 2186 -- Check_System_Aux -- 2187 ---------------------- 2188 2189 function Check_System_Aux return Boolean is 2190 Ent : Entity_Id; 2191 2192 begin 2193 if Chars (Lunit) = Name_System 2194 and then Scope (Lunit) = Standard_Standard 2195 and then Present_System_Aux 2196 then 2197 Ent := First_Entity (System_Aux_Id); 2198 while Present (Ent) loop 2199 if Referenced_Check_Spec (Ent) then 2200 return True; 2201 end if; 2202 2203 Next_Entity (Ent); 2204 end loop; 2205 end if; 2206 2207 return False; 2208 end Check_System_Aux; 2209 2210 --------------------------- 2211 -- Find_Package_Renaming -- 2212 --------------------------- 2213 2214 function Find_Package_Renaming 2215 (P : Entity_Id; 2216 L : Entity_Id) return Entity_Id 2217 is 2218 E1 : Entity_Id; 2219 R : Entity_Id; 2220 2221 begin 2222 Is_Visible_Renaming := False; 2223 2224 E1 := First_Entity (P); 2225 while Present (E1) loop 2226 if Ekind (E1) = E_Package 2227 and then Renamed_Object (E1) = L 2228 then 2229 Is_Visible_Renaming := not Is_Hidden (E1); 2230 return E1; 2231 2232 elsif Ekind (E1) = E_Package 2233 and then No (Renamed_Object (E1)) 2234 and then not Is_Generic_Instance (E1) 2235 then 2236 R := Find_Package_Renaming (E1, L); 2237 2238 if Present (R) then 2239 Is_Visible_Renaming := not Is_Hidden (R); 2240 return R; 2241 end if; 2242 end if; 2243 2244 Next_Entity (E1); 2245 end loop; 2246 2247 return Empty; 2248 end Find_Package_Renaming; 2249 2250 -------------------------- 2251 -- Has_Visible_Entities -- 2252 -------------------------- 2253 2254 function Has_Visible_Entities (P : Entity_Id) return Boolean is 2255 E : Entity_Id; 2256 2257 begin 2258 -- If unit in context is not a package, it is a subprogram that 2259 -- is not called or a generic unit that is not instantiated 2260 -- in the current unit, and warning is appropriate. 2261 2262 if Ekind (P) /= E_Package then 2263 return True; 2264 end if; 2265 2266 -- If unit comes from a limited_with clause, look for declaration 2267 -- of shadow entities. 2268 2269 if Present (Limited_View (P)) then 2270 E := First_Entity (Limited_View (P)); 2271 else 2272 E := First_Entity (P); 2273 end if; 2274 2275 while Present (E) 2276 and then E /= First_Private_Entity (P) 2277 loop 2278 if Comes_From_Source (E) 2279 or else Present (Limited_View (P)) 2280 then 2281 return True; 2282 end if; 2283 2284 Next_Entity (E); 2285 end loop; 2286 2287 return False; 2288 end Has_Visible_Entities; 2289 2290 -- Start of processing for Check_One_Unit 2291 2292 begin 2293 Cnode := Cunit (Unit); 2294 2295 -- Only do check in units that are part of the extended main unit. 2296 -- This is actually a necessary restriction, because in the case of 2297 -- subprogram acting as its own specification, there can be with's in 2298 -- subunits that we will not see. 2299 2300 if not In_Extended_Main_Source_Unit (Cnode) then 2301 return; 2302 2303 -- In configurable run time mode, we remove the bodies of non-inlined 2304 -- subprograms, which may lead to spurious warnings, which are 2305 -- clearly undesirable. 2306 2307 elsif Configurable_Run_Time_Mode 2308 and then Is_Predefined_File_Name (Unit_File_Name (Unit)) 2309 then 2310 return; 2311 end if; 2312 2313 -- Loop through context items in this unit 2314 2315 Item := First (Context_Items (Cnode)); 2316 while Present (Item) loop 2317 if Nkind (Item) = N_With_Clause 2318 and then not Implicit_With (Item) 2319 and then In_Extended_Main_Source_Unit (Item) 2320 then 2321 Lunit := Entity (Name (Item)); 2322 2323 -- Check if this unit is referenced (skip the check if this 2324 -- is explicitly marked by a pragma Unreferenced). 2325 2326 if not Referenced (Lunit) 2327 and then not Has_Unreferenced (Lunit) 2328 then 2329 -- Suppress warnings in internal units if not in -gnatg mode 2330 -- (these would be junk warnings for an application program, 2331 -- since they refer to problems in internal units). 2332 2333 if GNAT_Mode 2334 or else not Is_Internal_File_Name (Unit_File_Name (Unit)) 2335 then 2336 -- Here we definitely have a non-referenced unit. If it 2337 -- is the special call for a spec unit, then just set the 2338 -- flag to be read later. 2339 2340 if Unit = Spec_Unit then 2341 Set_Unreferenced_In_Spec (Item); 2342 2343 -- Otherwise simple unreferenced message, but skip this 2344 -- if no visible entities, because that is most likely a 2345 -- case where warning would be false positive (e.g. a 2346 -- package with only a linker options pragma and nothing 2347 -- else or a pragma elaborate with a body library task). 2348 2349 elsif Has_Visible_Entities (Entity (Name (Item))) then 2350 Error_Msg_N -- CODEFIX 2351 ("?u?unit& is not referenced!", Name (Item)); 2352 end if; 2353 end if; 2354 2355 -- If main unit is a renaming of this unit, then we consider 2356 -- the with to be OK (obviously it is needed in this case). 2357 -- This may be transitive: the unit in the with_clause may 2358 -- itself be a renaming, in which case both it and the main 2359 -- unit rename the same ultimate package. 2360 2361 elsif Present (Renamed_Entity (Munite)) 2362 and then 2363 (Renamed_Entity (Munite) = Lunit 2364 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit)) 2365 then 2366 null; 2367 2368 -- If this unit is referenced, and it is a package, we do 2369 -- another test, to see if any of the entities in the package 2370 -- are referenced. If none of the entities are referenced, we 2371 -- still post a warning. This occurs if the only use of the 2372 -- package is in a use clause, or in a package renaming 2373 -- declaration. This check is skipped for packages that are 2374 -- renamed in a spec, since the entities in such a package are 2375 -- visible to clients via the renaming. 2376 2377 elsif Ekind (Lunit) = E_Package 2378 and then not Renamed_In_Spec (Lunit) 2379 then 2380 -- If Is_Instantiated is set, it means that the package is 2381 -- implicitly instantiated (this is the case of parent 2382 -- instance or an actual for a generic package formal), and 2383 -- this counts as a reference. 2384 2385 if Is_Instantiated (Lunit) then 2386 null; 2387 2388 -- If no entities in package, and there is a pragma 2389 -- Elaborate_Body present, then assume that this with is 2390 -- done for purposes of this elaboration. 2391 2392 elsif No (First_Entity (Lunit)) 2393 and then Has_Pragma_Elaborate_Body (Lunit) 2394 then 2395 null; 2396 2397 -- Otherwise see if any entities have been referenced 2398 2399 else 2400 if Limited_Present (Item) then 2401 Ent := First_Entity (Limited_View (Lunit)); 2402 else 2403 Ent := First_Entity (Lunit); 2404 end if; 2405 2406 loop 2407 -- No more entities, and we did not find one that was 2408 -- referenced. Means we have a definite case of a with 2409 -- none of whose entities was referenced. 2410 2411 if No (Ent) then 2412 2413 -- If in spec, just set the flag 2414 2415 if Unit = Spec_Unit then 2416 Set_No_Entities_Ref_In_Spec (Item); 2417 2418 elsif Check_System_Aux then 2419 null; 2420 2421 -- Else give the warning 2422 2423 else 2424 -- Warn if we unreferenced flag set and we have 2425 -- not had serious errors. The reason we inhibit 2426 -- the message if there are errors is to prevent 2427 -- false positives from disabling expansion. 2428 2429 if not Has_Unreferenced (Entity (Name (Item))) 2430 and then Serious_Errors_Detected = 0 2431 then 2432 Error_Msg_N -- CODEFIX 2433 ("?u?no entities of & are referenced!", 2434 Name (Item)); 2435 end if; 2436 2437 -- Look for renamings of this package, and flag 2438 -- them as well. If the original package has 2439 -- warnings off, we suppress the warning on the 2440 -- renaming as well. 2441 2442 Pack := Find_Package_Renaming (Munite, Lunit); 2443 2444 if Present (Pack) 2445 and then not Has_Warnings_Off (Lunit) 2446 and then not Has_Unreferenced (Pack) 2447 then 2448 Error_Msg_NE -- CODEFIX 2449 ("?u?no entities of & are referenced!", 2450 Unit_Declaration_Node (Pack), 2451 Pack); 2452 end if; 2453 end if; 2454 2455 exit; 2456 2457 -- Case of entity being referenced. The reference may 2458 -- come from a limited_with_clause, in which case the 2459 -- limited view of the entity carries the flag. 2460 2461 elsif Referenced_Check_Spec (Ent) 2462 or else Referenced_As_LHS_Check_Spec (Ent) 2463 or else Referenced_As_Out_Parameter_Check_Spec (Ent) 2464 or else 2465 (From_Limited_With (Ent) 2466 and then Is_Incomplete_Type (Ent) 2467 and then Present (Non_Limited_View (Ent)) 2468 and then Referenced (Non_Limited_View (Ent))) 2469 then 2470 -- This means that the with is indeed fine, in that 2471 -- it is definitely needed somewhere, and we can 2472 -- quit worrying about this one... 2473 2474 -- Except for one little detail: if either of the 2475 -- flags was set during spec processing, this is 2476 -- where we complain that the with could be moved 2477 -- from the spec. If the spec contains a visible 2478 -- renaming of the package, inhibit warning to move 2479 -- with_clause to body. 2480 2481 if Ekind (Munite) = E_Package_Body then 2482 Pack := 2483 Find_Package_Renaming 2484 (Spec_Entity (Munite), Lunit); 2485 else 2486 Pack := Empty; 2487 end if; 2488 2489 -- If a renaming is present in the spec do not warn 2490 -- because the body or child unit may depend on it. 2491 2492 if Present (Pack) 2493 and then Renamed_Entity (Pack) = Lunit 2494 then 2495 exit; 2496 2497 elsif Unreferenced_In_Spec (Item) then 2498 Error_Msg_N -- CODEFIX 2499 ("?u?unit& is not referenced in spec!", 2500 Name (Item)); 2501 2502 elsif No_Entities_Ref_In_Spec (Item) then 2503 Error_Msg_N -- CODEFIX 2504 ("?u?no entities of & are referenced in spec!", 2505 Name (Item)); 2506 2507 else 2508 if Ekind (Ent) = E_Package then 2509 Check_Inner_Package (Ent); 2510 end if; 2511 2512 exit; 2513 end if; 2514 2515 if not Is_Visible_Renaming then 2516 Error_Msg_N -- CODEFIX 2517 ("\?u?with clause might be moved to body!", 2518 Name (Item)); 2519 end if; 2520 2521 exit; 2522 2523 -- Move to next entity to continue search 2524 2525 else 2526 Next_Entity (Ent); 2527 end if; 2528 end loop; 2529 end if; 2530 2531 -- For a generic package, the only interesting kind of 2532 -- reference is an instantiation, since entities cannot be 2533 -- referenced directly. 2534 2535 elsif Is_Generic_Unit (Lunit) then 2536 2537 -- Unit was never instantiated, set flag for case of spec 2538 -- call, or give warning for normal call. 2539 2540 if not Is_Instantiated (Lunit) then 2541 if Unit = Spec_Unit then 2542 Set_Unreferenced_In_Spec (Item); 2543 else 2544 Error_Msg_N -- CODEFIX 2545 ("?u?unit& is never instantiated!", Name (Item)); 2546 end if; 2547 2548 -- If unit was indeed instantiated, make sure that flag is 2549 -- not set showing it was uninstantiated in the spec, and if 2550 -- so, give warning. 2551 2552 elsif Unreferenced_In_Spec (Item) then 2553 Error_Msg_N 2554 ("?u?unit& is not instantiated in spec!", Name (Item)); 2555 Error_Msg_N -- CODEFIX 2556 ("\?u?with clause can be moved to body!", Name (Item)); 2557 end if; 2558 end if; 2559 end if; 2560 2561 Next (Item); 2562 end loop; 2563 end Check_One_Unit; 2564 2565 -- Start of processing for Check_Unused_Withs 2566 2567 begin 2568 -- Immediate return if no semantics or warning flag not set 2569 2570 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then 2571 return; 2572 end if; 2573 2574 Process_Deferred_References; 2575 2576 -- Flag any unused with clauses. For a subunit, check only the units 2577 -- in its context, not those of the parent, which may be needed by other 2578 -- subunits. We will get the full warnings when we compile the parent, 2579 -- but the following is helpful when compiling a subunit by itself. 2580 2581 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then 2582 if Current_Sem_Unit = Main_Unit then 2583 Check_One_Unit (Main_Unit); 2584 end if; 2585 2586 return; 2587 end if; 2588 2589 -- Process specified units 2590 2591 if Spec_Unit = No_Unit then 2592 2593 -- For main call, check all units 2594 2595 for Unit in Main_Unit .. Last_Unit loop 2596 Check_One_Unit (Unit); 2597 end loop; 2598 2599 else 2600 -- For call for spec, check only the spec 2601 2602 Check_One_Unit (Spec_Unit); 2603 end if; 2604 end Check_Unused_Withs; 2605 2606 --------------------------------- 2607 -- Generic_Package_Spec_Entity -- 2608 --------------------------------- 2609 2610 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is 2611 S : Entity_Id; 2612 2613 begin 2614 if Is_Package_Body_Entity (E) then 2615 return False; 2616 2617 else 2618 S := Scope (E); 2619 loop 2620 if S = Standard_Standard then 2621 return False; 2622 2623 elsif Ekind (S) = E_Generic_Package then 2624 return True; 2625 2626 elsif Ekind (S) = E_Package then 2627 S := Scope (S); 2628 2629 else 2630 return False; 2631 end if; 2632 end loop; 2633 end if; 2634 end Generic_Package_Spec_Entity; 2635 2636 ---------------------- 2637 -- Goto_Spec_Entity -- 2638 ---------------------- 2639 2640 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is 2641 begin 2642 if Is_Formal (E) 2643 and then Present (Spec_Entity (E)) 2644 then 2645 return Spec_Entity (E); 2646 else 2647 return E; 2648 end if; 2649 end Goto_Spec_Entity; 2650 2651 -------------------------------------- 2652 -- Has_Pragma_Unmodified_Check_Spec -- 2653 -------------------------------------- 2654 2655 function Has_Pragma_Unmodified_Check_Spec 2656 (E : Entity_Id) return Boolean 2657 is 2658 begin 2659 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2660 2661 -- Note: use of OR instead of OR ELSE here is deliberate, we want 2662 -- to mess with Unmodified flags on both body and spec entities. 2663 2664 return Has_Unmodified (E) 2665 or 2666 Has_Unmodified (Spec_Entity (E)); 2667 2668 else 2669 return Has_Unmodified (E); 2670 end if; 2671 end Has_Pragma_Unmodified_Check_Spec; 2672 2673 ---------------------------------------- 2674 -- Has_Pragma_Unreferenced_Check_Spec -- 2675 ---------------------------------------- 2676 2677 function Has_Pragma_Unreferenced_Check_Spec 2678 (E : Entity_Id) return Boolean 2679 is 2680 begin 2681 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2682 2683 -- Note: use of OR here instead of OR ELSE is deliberate, we want 2684 -- to mess with flags on both entities. 2685 2686 return Has_Unreferenced (E) 2687 or 2688 Has_Unreferenced (Spec_Entity (E)); 2689 2690 else 2691 return Has_Unreferenced (E); 2692 end if; 2693 end Has_Pragma_Unreferenced_Check_Spec; 2694 2695 ---------------- 2696 -- Initialize -- 2697 ---------------- 2698 2699 procedure Initialize is 2700 begin 2701 Warnings_Off_Pragmas.Init; 2702 Unreferenced_Entities.Init; 2703 In_Out_Warnings.Init; 2704 end Initialize; 2705 2706 ------------------------------------ 2707 -- Never_Set_In_Source_Check_Spec -- 2708 ------------------------------------ 2709 2710 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is 2711 begin 2712 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2713 return Never_Set_In_Source (E) 2714 and then 2715 Never_Set_In_Source (Spec_Entity (E)); 2716 else 2717 return Never_Set_In_Source (E); 2718 end if; 2719 end Never_Set_In_Source_Check_Spec; 2720 2721 ------------------------------------- 2722 -- Operand_Has_Warnings_Suppressed -- 2723 ------------------------------------- 2724 2725 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is 2726 2727 function Check_For_Warnings (N : Node_Id) return Traverse_Result; 2728 -- Function used to check one node to see if it is or was originally 2729 -- a reference to an entity for which Warnings are off. If so, Abandon 2730 -- is returned, otherwise OK_Orig is returned to continue the traversal 2731 -- of the original expression. 2732 2733 function Traverse is new Traverse_Func (Check_For_Warnings); 2734 -- Function used to traverse tree looking for warnings 2735 2736 ------------------------ 2737 -- Check_For_Warnings -- 2738 ------------------------ 2739 2740 function Check_For_Warnings (N : Node_Id) return Traverse_Result is 2741 R : constant Node_Id := Original_Node (N); 2742 2743 begin 2744 if Nkind (R) in N_Has_Entity 2745 and then Present (Entity (R)) 2746 and then Has_Warnings_Off (Entity (R)) 2747 then 2748 return Abandon; 2749 else 2750 return OK_Orig; 2751 end if; 2752 end Check_For_Warnings; 2753 2754 -- Start of processing for Operand_Has_Warnings_Suppressed 2755 2756 begin 2757 return Traverse (N) = Abandon; 2758 2759 -- If any exception occurs, then something has gone wrong, and this is 2760 -- only a minor aesthetic issue anyway, so just say we did not find what 2761 -- we are looking for, rather than blow up. 2762 2763 exception 2764 when others => 2765 return False; 2766 end Operand_Has_Warnings_Suppressed; 2767 2768 ----------------------------------------- 2769 -- Output_Non_Modified_In_Out_Warnings -- 2770 ----------------------------------------- 2771 2772 procedure Output_Non_Modified_In_Out_Warnings is 2773 2774 function No_Warn_On_In_Out (E : Entity_Id) return Boolean; 2775 -- Given a formal parameter entity E, determines if there is a reason to 2776 -- suppress IN OUT warnings (not modified, could be IN) for formals of 2777 -- the subprogram. We suppress these warnings if Warnings Off is set, or 2778 -- if we have seen the address of the subprogram being taken, or if the 2779 -- subprogram is used as a generic actual (in the latter cases the 2780 -- context may force use of IN OUT, even if the parameter is not 2781 -- modifies for this particular case. 2782 2783 ----------------------- 2784 -- No_Warn_On_In_Out -- 2785 ----------------------- 2786 2787 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is 2788 S : constant Entity_Id := Scope (E); 2789 SE : constant Entity_Id := Spec_Entity (E); 2790 2791 begin 2792 -- Do not warn if address is taken, since funny business may be going 2793 -- on in treating the parameter indirectly as IN OUT. 2794 2795 if Address_Taken (S) 2796 or else (Present (SE) and then Address_Taken (Scope (SE))) 2797 then 2798 return True; 2799 2800 -- Do not warn if used as a generic actual, since the generic may be 2801 -- what is forcing the use of an "unnecessary" IN OUT. 2802 2803 elsif Used_As_Generic_Actual (S) 2804 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE))) 2805 then 2806 return True; 2807 2808 -- Else test warnings off 2809 2810 elsif Warnings_Off_Check_Spec (S) then 2811 return True; 2812 2813 -- All tests for suppressing warning failed 2814 2815 else 2816 return False; 2817 end if; 2818 end No_Warn_On_In_Out; 2819 2820 -- Start of processing for Output_Non_Modified_In_Out_Warnings 2821 2822 begin 2823 -- Loop through entities for which a warning may be needed 2824 2825 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop 2826 declare 2827 E1 : constant Entity_Id := In_Out_Warnings.Table (J); 2828 2829 begin 2830 -- Suppress warning in specific cases (see details in comments for 2831 -- No_Warn_On_In_Out), or if there is a pragma Unmodified. 2832 2833 if Has_Pragma_Unmodified_Check_Spec (E1) 2834 or else No_Warn_On_In_Out (E1) 2835 then 2836 null; 2837 2838 -- Here we generate the warning 2839 2840 else 2841 -- If -gnatwc is set then output message that we could be IN 2842 2843 if not Is_Trivial_Subprogram (Scope (E1)) then 2844 if Warn_On_Constant then 2845 Error_Msg_N 2846 ("?u?formal parameter & is not modified!", E1); 2847 Error_Msg_N 2848 ("\?u?mode could be IN instead of `IN OUT`!", E1); 2849 2850 -- We do not generate warnings for IN OUT parameters 2851 -- unless we have at least -gnatwu. This is deliberately 2852 -- inconsistent with the treatment of variables, but 2853 -- otherwise we get too many unexpected warnings in 2854 -- default mode. 2855 2856 elsif Check_Unreferenced then 2857 Error_Msg_N 2858 ("?u?formal parameter& is read but " 2859 & "never assigned!", E1); 2860 end if; 2861 end if; 2862 2863 -- Kill any other warnings on this entity, since this is the 2864 -- one that should dominate any other unreferenced warning. 2865 2866 Set_Warnings_Off (E1); 2867 end if; 2868 end; 2869 end loop; 2870 end Output_Non_Modified_In_Out_Warnings; 2871 2872 ---------------------------------------- 2873 -- Output_Obsolescent_Entity_Warnings -- 2874 ---------------------------------------- 2875 2876 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is 2877 P : constant Node_Id := Parent (N); 2878 S : Entity_Id; 2879 2880 begin 2881 S := Current_Scope; 2882 2883 -- Do not output message if we are the scope of standard. This means 2884 -- we have a reference from a context clause from when it is originally 2885 -- processed, and that's too early to tell whether it is an obsolescent 2886 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make 2887 -- sure that we have a later call when the scope is available. This test 2888 -- also eliminates all messages for use clauses, which is fine (we do 2889 -- not want messages for use clauses, since they are always redundant 2890 -- with respect to the associated with clause). 2891 2892 if S = Standard_Standard then 2893 return; 2894 end if; 2895 2896 -- Do not output message if we are in scope of an obsolescent package 2897 -- or subprogram. 2898 2899 loop 2900 if Is_Obsolescent (S) then 2901 return; 2902 end if; 2903 2904 S := Scope (S); 2905 exit when S = Standard_Standard; 2906 end loop; 2907 2908 -- Here we will output the message 2909 2910 Error_Msg_Sloc := Sloc (E); 2911 2912 -- Case of with clause 2913 2914 if Nkind (P) = N_With_Clause then 2915 if Ekind (E) = E_Package then 2916 Error_Msg_NE 2917 ("??with of obsolescent package& declared#", N, E); 2918 elsif Ekind (E) = E_Procedure then 2919 Error_Msg_NE 2920 ("??with of obsolescent procedure& declared#", N, E); 2921 else 2922 Error_Msg_NE 2923 ("??with of obsolescent function& declared#", N, E); 2924 end if; 2925 2926 -- If we do not have a with clause, then ignore any reference to an 2927 -- obsolescent package name. We only want to give the one warning of 2928 -- withing the package, not one each time it is used to qualify. 2929 2930 elsif Ekind (E) = E_Package then 2931 return; 2932 2933 -- Procedure call statement 2934 2935 elsif Nkind (P) = N_Procedure_Call_Statement then 2936 Error_Msg_NE 2937 ("??call to obsolescent procedure& declared#", N, E); 2938 2939 -- Function call 2940 2941 elsif Nkind (P) = N_Function_Call then 2942 Error_Msg_NE 2943 ("??call to obsolescent function& declared#", N, E); 2944 2945 -- Reference to obsolescent type 2946 2947 elsif Is_Type (E) then 2948 Error_Msg_NE 2949 ("??reference to obsolescent type& declared#", N, E); 2950 2951 -- Reference to obsolescent component 2952 2953 elsif Ekind_In (E, E_Component, E_Discriminant) then 2954 Error_Msg_NE 2955 ("??reference to obsolescent component& declared#", N, E); 2956 2957 -- Reference to obsolescent variable 2958 2959 elsif Ekind (E) = E_Variable then 2960 Error_Msg_NE 2961 ("??reference to obsolescent variable& declared#", N, E); 2962 2963 -- Reference to obsolescent constant 2964 2965 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then 2966 Error_Msg_NE 2967 ("??reference to obsolescent constant& declared#", N, E); 2968 2969 -- Reference to obsolescent enumeration literal 2970 2971 elsif Ekind (E) = E_Enumeration_Literal then 2972 Error_Msg_NE 2973 ("??reference to obsolescent enumeration literal& declared#", N, E); 2974 2975 -- Generic message for any other case we missed 2976 2977 else 2978 Error_Msg_NE 2979 ("??reference to obsolescent entity& declared#", N, E); 2980 end if; 2981 2982 -- Output additional warning if present 2983 2984 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop 2985 if Obsolescent_Warnings.Table (J).Ent = E then 2986 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg); 2987 Error_Msg_Strlen := Name_Len; 2988 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len); 2989 Error_Msg_N ("\\??~", N); 2990 exit; 2991 end if; 2992 end loop; 2993 end Output_Obsolescent_Entity_Warnings; 2994 2995 ---------------------------------- 2996 -- Output_Unreferenced_Messages -- 2997 ---------------------------------- 2998 2999 procedure Output_Unreferenced_Messages is 3000 begin 3001 for J in Unreferenced_Entities.First .. 3002 Unreferenced_Entities.Last 3003 loop 3004 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J)); 3005 end loop; 3006 end Output_Unreferenced_Messages; 3007 3008 ----------------------------------------- 3009 -- Output_Unused_Warnings_Off_Warnings -- 3010 ----------------------------------------- 3011 3012 procedure Output_Unused_Warnings_Off_Warnings is 3013 begin 3014 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop 3015 declare 3016 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J); 3017 N : Node_Id renames Wentry.N; 3018 E : Node_Id renames Wentry.E; 3019 3020 begin 3021 -- Turn off Warnings_Off, or we won't get the warning 3022 3023 Set_Warnings_Off (E, False); 3024 3025 -- Nothing to do if pragma was used to suppress a general warning 3026 3027 if Warnings_Off_Used (E) then 3028 null; 3029 3030 -- If pragma was used both in unmodified and unreferenced contexts 3031 -- then that's as good as the general case, no warning. 3032 3033 elsif Warnings_Off_Used_Unmodified (E) 3034 and 3035 Warnings_Off_Used_Unreferenced (E) 3036 then 3037 null; 3038 3039 -- Used only in context where Unmodified would have worked 3040 3041 elsif Warnings_Off_Used_Unmodified (E) then 3042 Error_Msg_NE 3043 ("?W?could use Unmodified instead of " 3044 & "Warnings Off for &", Pragma_Identifier (N), E); 3045 3046 -- Used only in context where Unreferenced would have worked 3047 3048 elsif Warnings_Off_Used_Unreferenced (E) then 3049 Error_Msg_NE 3050 ("?W?could use Unreferenced instead of " 3051 & "Warnings Off for &", Pragma_Identifier (N), E); 3052 3053 -- Not used at all 3054 3055 else 3056 Error_Msg_NE 3057 ("?W?pragma Warnings Off for & unused, " 3058 & "could be omitted", N, E); 3059 end if; 3060 end; 3061 end loop; 3062 end Output_Unused_Warnings_Off_Warnings; 3063 3064 --------------------------- 3065 -- Referenced_Check_Spec -- 3066 --------------------------- 3067 3068 function Referenced_Check_Spec (E : Entity_Id) return Boolean is 3069 begin 3070 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3071 return Referenced (E) or else Referenced (Spec_Entity (E)); 3072 else 3073 return Referenced (E); 3074 end if; 3075 end Referenced_Check_Spec; 3076 3077 ---------------------------------- 3078 -- Referenced_As_LHS_Check_Spec -- 3079 ---------------------------------- 3080 3081 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is 3082 begin 3083 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3084 return Referenced_As_LHS (E) 3085 or else Referenced_As_LHS (Spec_Entity (E)); 3086 else 3087 return Referenced_As_LHS (E); 3088 end if; 3089 end Referenced_As_LHS_Check_Spec; 3090 3091 -------------------------------------------- 3092 -- Referenced_As_Out_Parameter_Check_Spec -- 3093 -------------------------------------------- 3094 3095 function Referenced_As_Out_Parameter_Check_Spec 3096 (E : Entity_Id) return Boolean 3097 is 3098 begin 3099 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3100 return Referenced_As_Out_Parameter (E) 3101 or else Referenced_As_Out_Parameter (Spec_Entity (E)); 3102 else 3103 return Referenced_As_Out_Parameter (E); 3104 end if; 3105 end Referenced_As_Out_Parameter_Check_Spec; 3106 3107 ----------------------------- 3108 -- Warn_On_Known_Condition -- 3109 ----------------------------- 3110 3111 procedure Warn_On_Known_Condition (C : Node_Id) is 3112 P : Node_Id; 3113 Orig : constant Node_Id := Original_Node (C); 3114 Test_Result : Boolean; 3115 3116 function Is_Known_Branch return Boolean; 3117 -- If the type of the condition is Boolean, the constant value of the 3118 -- condition is a boolean literal. If the type is a derived boolean 3119 -- type, the constant is wrapped in a type conversion of the derived 3120 -- literal. If the value of the condition is not a literal, no warnings 3121 -- can be produced. This function returns True if the result can be 3122 -- determined, and Test_Result is set True/False accordingly. Otherwise 3123 -- False is returned, and Test_Result is unchanged. 3124 3125 procedure Track (N : Node_Id; Loc : Node_Id); 3126 -- Adds continuation warning(s) pointing to reason (assignment or test) 3127 -- for the operand of the conditional having a known value (or at least 3128 -- enough is known about the value to issue the warning). N is the node 3129 -- which is judged to have a known value. Loc is the warning location. 3130 3131 --------------------- 3132 -- Is_Known_Branch -- 3133 --------------------- 3134 3135 function Is_Known_Branch return Boolean is 3136 begin 3137 if Etype (C) = Standard_Boolean 3138 and then Is_Entity_Name (C) 3139 and then 3140 (Entity (C) = Standard_False or else Entity (C) = Standard_True) 3141 then 3142 Test_Result := Entity (C) = Standard_True; 3143 return True; 3144 3145 elsif Is_Boolean_Type (Etype (C)) 3146 and then Nkind (C) = N_Unchecked_Type_Conversion 3147 and then Is_Entity_Name (Expression (C)) 3148 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal 3149 then 3150 Test_Result := 3151 Chars (Entity (Expression (C))) = Chars (Standard_True); 3152 return True; 3153 3154 else 3155 return False; 3156 end if; 3157 end Is_Known_Branch; 3158 3159 ----------- 3160 -- Track -- 3161 ----------- 3162 3163 procedure Track (N : Node_Id; Loc : Node_Id) is 3164 Nod : constant Node_Id := Original_Node (N); 3165 3166 begin 3167 if Nkind (Nod) in N_Op_Compare then 3168 Track (Left_Opnd (Nod), Loc); 3169 Track (Right_Opnd (Nod), Loc); 3170 3171 elsif Is_Entity_Name (Nod) 3172 and then Is_Object (Entity (Nod)) 3173 then 3174 declare 3175 CV : constant Node_Id := Current_Value (Entity (Nod)); 3176 3177 begin 3178 if Present (CV) then 3179 Error_Msg_Sloc := Sloc (CV); 3180 3181 if Nkind (CV) not in N_Subexpr then 3182 Error_Msg_N ("\\?(see test #)", Loc); 3183 3184 elsif Nkind (Parent (CV)) = 3185 N_Case_Statement_Alternative 3186 then 3187 Error_Msg_N ("\\?(see case alternative #)", Loc); 3188 3189 else 3190 Error_Msg_N ("\\?(see assignment #)", Loc); 3191 end if; 3192 end if; 3193 end; 3194 end if; 3195 end Track; 3196 3197 -- Start of processing for Warn_On_Known_Condition 3198 3199 begin 3200 -- Adjust SCO condition if from source 3201 3202 if Generate_SCO 3203 and then Comes_From_Source (Orig) 3204 and then Is_Known_Branch 3205 then 3206 declare 3207 Atrue : Boolean; 3208 3209 begin 3210 Atrue := Test_Result; 3211 3212 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then 3213 Atrue := not Atrue; 3214 end if; 3215 3216 Set_SCO_Condition (Orig, Atrue); 3217 end; 3218 end if; 3219 3220 -- Argument replacement in an inlined body can make conditions static. 3221 -- Do not emit warnings in this case. 3222 3223 if In_Inlined_Body then 3224 return; 3225 end if; 3226 3227 if Constant_Condition_Warnings 3228 and then Is_Known_Branch 3229 and then Comes_From_Source (Orig) 3230 and then not In_Instance 3231 then 3232 -- Don't warn if comparison of result of attribute against a constant 3233 -- value, since this is likely legitimate conditional compilation. 3234 3235 if Nkind (Orig) in N_Op_Compare 3236 and then Compile_Time_Known_Value (Right_Opnd (Orig)) 3237 and then Nkind (Original_Node (Left_Opnd (Orig))) = 3238 N_Attribute_Reference 3239 then 3240 return; 3241 end if; 3242 3243 -- See if this is in a statement or a declaration 3244 3245 P := Parent (C); 3246 loop 3247 -- If tree is not attached, do not issue warning (this is very 3248 -- peculiar, and probably arises from some other error condition) 3249 3250 if No (P) then 3251 return; 3252 3253 -- If we are in a declaration, then no warning, since in practice 3254 -- conditionals in declarations are used for intended tests which 3255 -- may be known at compile time, e.g. things like 3256 3257 -- x : constant Integer := 2 + (Word'Size = 32); 3258 3259 -- And a warning is annoying in such cases 3260 3261 elsif Nkind (P) in N_Declaration 3262 or else 3263 Nkind (P) in N_Later_Decl_Item 3264 then 3265 return; 3266 3267 -- Don't warn in assert or check pragma, since presumably tests in 3268 -- such a context are very definitely intended, and might well be 3269 -- known at compile time. Note that we have to test the original 3270 -- node, since assert pragmas get rewritten at analysis time. 3271 3272 elsif Nkind (Original_Node (P)) = N_Pragma 3273 and then Nam_In (Pragma_Name (Original_Node (P)), Name_Assert, 3274 Name_Check) 3275 then 3276 return; 3277 end if; 3278 3279 exit when Is_Statement (P); 3280 P := Parent (P); 3281 end loop; 3282 3283 -- Here we issue the warning unless some sub-operand has warnings 3284 -- set off, in which case we suppress the warning for the node. If 3285 -- the original expression is an inequality, it has been expanded 3286 -- into a negation, and the value of the original expression is the 3287 -- negation of the equality. If the expression is an entity that 3288 -- appears within a negation, it is clearer to flag the negation 3289 -- itself, and report on its constant value. 3290 3291 if not Operand_Has_Warnings_Suppressed (C) then 3292 declare 3293 True_Branch : Boolean := Test_Result; 3294 Cond : Node_Id := C; 3295 3296 begin 3297 if Present (Parent (C)) 3298 and then Nkind (Parent (C)) = N_Op_Not 3299 then 3300 True_Branch := not True_Branch; 3301 Cond := Parent (C); 3302 end if; 3303 3304 if True_Branch then 3305 if Is_Entity_Name (Original_Node (C)) 3306 and then Nkind (Cond) /= N_Op_Not 3307 then 3308 Error_Msg_NE 3309 ("object & is always True?c?", Cond, Original_Node (C)); 3310 Track (Original_Node (C), Cond); 3311 3312 else 3313 Error_Msg_N ("condition is always True?c?", Cond); 3314 Track (Cond, Cond); 3315 end if; 3316 3317 else 3318 Error_Msg_N ("condition is always False?c?", Cond); 3319 Track (Cond, Cond); 3320 end if; 3321 end; 3322 end if; 3323 end if; 3324 end Warn_On_Known_Condition; 3325 3326 --------------------------------------- 3327 -- Warn_On_Modified_As_Out_Parameter -- 3328 --------------------------------------- 3329 3330 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is 3331 begin 3332 return 3333 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E)) 3334 or else Warn_On_All_Unread_Out_Parameters; 3335 end Warn_On_Modified_As_Out_Parameter; 3336 3337 --------------------------------- 3338 -- Warn_On_Overlapping_Actuals -- 3339 --------------------------------- 3340 3341 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is 3342 Act1, Act2 : Node_Id; 3343 Form1, Form2 : Entity_Id; 3344 3345 function Is_Covered_Formal (Formal : Node_Id) return Boolean; 3346 -- Return True if Formal is covered by the rule 3347 3348 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean; 3349 -- Two names are known to refer to the same object if the two names 3350 -- are known to denote the same object; or one of the names is a 3351 -- selected_component, indexed_component, or slice and its prefix is 3352 -- known to refer to the same object as the other name; or one of the 3353 -- two names statically denotes a renaming declaration whose renamed 3354 -- object_name is known to refer to the same object as the other name 3355 -- (RM 6.4.1(6.11/3)) 3356 3357 ----------------------- 3358 -- Refer_Same_Object -- 3359 ----------------------- 3360 3361 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is 3362 begin 3363 return Denotes_Same_Object (Act1, Act2) 3364 or else Denotes_Same_Prefix (Act1, Act2); 3365 end Refer_Same_Object; 3366 3367 ----------------------- 3368 -- Is_Covered_Formal -- 3369 ----------------------- 3370 3371 function Is_Covered_Formal (Formal : Node_Id) return Boolean is 3372 begin 3373 return 3374 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter) 3375 and then (Is_Elementary_Type (Etype (Formal)) 3376 or else Is_Record_Type (Etype (Formal)) 3377 or else Is_Array_Type (Etype (Formal))); 3378 end Is_Covered_Formal; 3379 3380 begin 3381 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then 3382 return; 3383 end if; 3384 3385 -- Exclude calls rewritten as enumeration literals 3386 3387 if Nkind (N) not in N_Subprogram_Call 3388 and then Nkind (N) /= N_Entry_Call_Statement 3389 then 3390 return; 3391 end if; 3392 3393 -- If a call C has two or more parameters of mode in out or out that are 3394 -- of an elementary type, then the call is legal only if for each name 3395 -- N that is passed as a parameter of mode in out or out to the call C, 3396 -- there is no other name among the other parameters of mode in out or 3397 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3)) 3398 3399 -- If appropriate warning switch is set, we also report warnings on 3400 -- overlapping parameters that are record types or array types. 3401 3402 Form1 := First_Formal (Subp); 3403 Act1 := First_Actual (N); 3404 while Present (Form1) and then Present (Act1) loop 3405 if Is_Covered_Formal (Form1) then 3406 Form2 := First_Formal (Subp); 3407 Act2 := First_Actual (N); 3408 while Present (Form2) and then Present (Act2) loop 3409 if Form1 /= Form2 3410 and then Is_Covered_Formal (Form2) 3411 and then Refer_Same_Object (Act1, Act2) 3412 then 3413 -- Guard against previous errors 3414 3415 if Error_Posted (N) 3416 or else No (Etype (Act1)) 3417 or else No (Etype (Act2)) 3418 then 3419 null; 3420 3421 -- If the actual is a function call in prefix notation, 3422 -- there is no real overlap. 3423 3424 elsif Nkind (Act2) = N_Function_Call then 3425 null; 3426 3427 -- If type is not by-copy, assume that aliasing is intended 3428 3429 elsif 3430 Present (Underlying_Type (Etype (Form1))) 3431 and then 3432 (Is_By_Reference_Type (Underlying_Type (Etype (Form1))) 3433 or else 3434 Convention (Underlying_Type (Etype (Form1))) = 3435 Convention_Ada_Pass_By_Reference) 3436 then 3437 null; 3438 3439 -- Under Ada 2012 we only report warnings on overlapping 3440 -- arrays and record types if switch is set. 3441 3442 elsif Ada_Version >= Ada_2012 3443 and then not Is_Elementary_Type (Etype (Form1)) 3444 and then not Warn_On_Overlap 3445 then 3446 null; 3447 3448 -- Here we may need to issue overlap message 3449 3450 else 3451 Error_Msg_Warn := 3452 3453 -- Overlap checking is an error only in Ada 2012. For 3454 -- earlier versions of Ada, this is a warning. 3455 3456 Ada_Version < Ada_2012 3457 3458 -- Overlap is only illegal in Ada 2012 in the case of 3459 -- elementary types (passed by copy). For other types, 3460 -- we always have a warning in all Ada versions. 3461 3462 or else not Is_Elementary_Type (Etype (Form1)) 3463 3464 -- Finally, debug flag -gnatd.E changes the error to a 3465 -- warning even in Ada 2012 mode. 3466 3467 or else Error_To_Warning; 3468 3469 declare 3470 Act : Node_Id; 3471 Form : Entity_Id; 3472 3473 begin 3474 -- Find matching actual 3475 3476 Act := First_Actual (N); 3477 Form := First_Formal (Subp); 3478 while Act /= Act2 loop 3479 Next_Formal (Form); 3480 Next_Actual (Act); 3481 end loop; 3482 3483 if Is_Elementary_Type (Etype (Act1)) 3484 and then Ekind (Form2) = E_In_Parameter 3485 then 3486 null; -- No real aliasing 3487 3488 elsif Is_Elementary_Type (Etype (Act2)) 3489 and then Ekind (Form2) = E_In_Parameter 3490 then 3491 null; -- Ditto 3492 3493 -- If the call was written in prefix notation, and 3494 -- thus its prefix before rewriting was a selected 3495 -- component, count only visible actuals in the call. 3496 3497 elsif Is_Entity_Name (First_Actual (N)) 3498 and then Nkind (Original_Node (N)) = Nkind (N) 3499 and then Nkind (Name (Original_Node (N))) = 3500 N_Selected_Component 3501 and then 3502 Is_Entity_Name (Prefix (Name (Original_Node (N)))) 3503 and then 3504 Entity (Prefix (Name (Original_Node (N)))) = 3505 Entity (First_Actual (N)) 3506 then 3507 if Act1 = First_Actual (N) then 3508 Error_Msg_FE 3509 ("<`IN OUT` prefix overlaps with " 3510 & "actual for&", Act1, Form); 3511 3512 else 3513 -- For greater clarity, give name of formal 3514 3515 Error_Msg_Node_2 := Form; 3516 Error_Msg_FE 3517 ("<writable actual for & overlaps with " 3518 & "actual for&", Act1, Form); 3519 end if; 3520 3521 else 3522 -- For greater clarity, give name of formal 3523 3524 Error_Msg_Node_2 := Form; 3525 3526 -- This is one of the messages 3527 3528 Error_Msg_FE 3529 ("<writable actual for & overlaps with " 3530 & "actual for&", Act1, Form1); 3531 end if; 3532 end; 3533 end if; 3534 3535 return; 3536 end if; 3537 3538 Next_Formal (Form2); 3539 Next_Actual (Act2); 3540 end loop; 3541 end if; 3542 3543 Next_Formal (Form1); 3544 Next_Actual (Act1); 3545 end loop; 3546 end Warn_On_Overlapping_Actuals; 3547 3548 ------------------------------ 3549 -- Warn_On_Suspicious_Index -- 3550 ------------------------------ 3551 3552 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is 3553 3554 Low_Bound : Uint; 3555 -- Set to lower bound for a suspicious type 3556 3557 Ent : Entity_Id; 3558 -- Entity for array reference 3559 3560 Typ : Entity_Id; 3561 -- Array type 3562 3563 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean; 3564 -- Tests to see if Typ is a type for which we may have a suspicious 3565 -- index, namely an unconstrained array type, whose lower bound is 3566 -- either zero or one. If so, True is returned, and Low_Bound is set 3567 -- to this lower bound. If not, False is returned, and Low_Bound is 3568 -- undefined on return. 3569 -- 3570 -- For now, we limit this to standard string types, so any other 3571 -- unconstrained types return False. We may change our minds on this 3572 -- later on, but strings seem the most important case. 3573 3574 procedure Test_Suspicious_Index; 3575 -- Test if index is of suspicious type and if so, generate warning 3576 3577 ------------------------ 3578 -- Is_Suspicious_Type -- 3579 ------------------------ 3580 3581 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is 3582 LB : Node_Id; 3583 3584 begin 3585 if Is_Array_Type (Typ) 3586 and then not Is_Constrained (Typ) 3587 and then Number_Dimensions (Typ) = 1 3588 and then (Root_Type (Typ) = Standard_String 3589 or else 3590 Root_Type (Typ) = Standard_Wide_String 3591 or else 3592 Root_Type (Typ) = Standard_Wide_Wide_String) 3593 and then not Has_Warnings_Off (Typ) 3594 then 3595 LB := Type_Low_Bound (Etype (First_Index (Typ))); 3596 3597 if Compile_Time_Known_Value (LB) then 3598 Low_Bound := Expr_Value (LB); 3599 return Low_Bound = Uint_0 or else Low_Bound = Uint_1; 3600 end if; 3601 end if; 3602 3603 return False; 3604 end Is_Suspicious_Type; 3605 3606 --------------------------- 3607 -- Test_Suspicious_Index -- 3608 --------------------------- 3609 3610 procedure Test_Suspicious_Index is 3611 3612 function Length_Reference (N : Node_Id) return Boolean; 3613 -- Check if node N is of the form Name'Length 3614 3615 procedure Warn1; 3616 -- Generate first warning line 3617 3618 ---------------------- 3619 -- Length_Reference -- 3620 ---------------------- 3621 3622 function Length_Reference (N : Node_Id) return Boolean is 3623 R : constant Node_Id := Original_Node (N); 3624 begin 3625 return 3626 Nkind (R) = N_Attribute_Reference 3627 and then Attribute_Name (R) = Name_Length 3628 and then Is_Entity_Name (Prefix (R)) 3629 and then Entity (Prefix (R)) = Ent; 3630 end Length_Reference; 3631 3632 ----------- 3633 -- Warn1 -- 3634 ----------- 3635 3636 procedure Warn1 is 3637 begin 3638 Error_Msg_Uint_1 := Low_Bound; 3639 Error_Msg_FE -- CODEFIX 3640 ("?w?index for& may assume lower bound of^", X, Ent); 3641 end Warn1; 3642 3643 -- Start of processing for Test_Suspicious_Index 3644 3645 begin 3646 -- Nothing to do if subscript does not come from source (we don't 3647 -- want to give garbage warnings on compiler expanded code, e.g. the 3648 -- loops generated for slice assignments. Such junk warnings would 3649 -- be placed on source constructs with no subscript in sight). 3650 3651 if not Comes_From_Source (Original_Node (X)) then 3652 return; 3653 end if; 3654 3655 -- Case where subscript is a constant integer 3656 3657 if Nkind (X) = N_Integer_Literal then 3658 Warn1; 3659 3660 -- Case where original form of subscript is an integer literal 3661 3662 if Nkind (Original_Node (X)) = N_Integer_Literal then 3663 if Intval (X) = Low_Bound then 3664 Error_Msg_FE -- CODEFIX 3665 ("\?w?suggested replacement: `&''First`", X, Ent); 3666 else 3667 Error_Msg_Uint_1 := Intval (X) - Low_Bound; 3668 Error_Msg_FE -- CODEFIX 3669 ("\?w?suggested replacement: `&''First + ^`", X, Ent); 3670 3671 end if; 3672 3673 -- Case where original form of subscript is more complex 3674 3675 else 3676 -- Build string X'First - 1 + expression where the expression 3677 -- is the original subscript. If the expression starts with "1 3678 -- + ", then the "- 1 + 1" is elided. 3679 3680 Error_Msg_String (1 .. 13) := "'First - 1 + "; 3681 Error_Msg_Strlen := 13; 3682 3683 declare 3684 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X))); 3685 Tref : constant Source_Buffer_Ptr := 3686 Source_Text (Get_Source_File_Index (Sref)); 3687 -- Tref (Sref) is used to scan the subscript 3688 3689 Pctr : Natural; 3690 -- Parentheses counter when scanning subscript 3691 3692 begin 3693 -- Tref (Sref) points to start of subscript 3694 3695 -- Elide - 1 if subscript starts with 1 + 3696 3697 if Tref (Sref .. Sref + 2) = "1 +" then 3698 Error_Msg_Strlen := Error_Msg_Strlen - 6; 3699 Sref := Sref + 2; 3700 3701 elsif Tref (Sref .. Sref + 1) = "1+" then 3702 Error_Msg_Strlen := Error_Msg_Strlen - 6; 3703 Sref := Sref + 1; 3704 end if; 3705 3706 -- Now we will copy the subscript to the string buffer 3707 3708 Pctr := 0; 3709 loop 3710 -- Count parens, exit if terminating right paren. Note 3711 -- check to ignore paren appearing as character literal. 3712 3713 if Tref (Sref + 1) = ''' 3714 and then 3715 Tref (Sref - 1) = ''' 3716 then 3717 null; 3718 else 3719 if Tref (Sref) = '(' then 3720 Pctr := Pctr + 1; 3721 elsif Tref (Sref) = ')' then 3722 exit when Pctr = 0; 3723 Pctr := Pctr - 1; 3724 end if; 3725 end if; 3726 3727 -- Done if terminating double dot (slice case) 3728 3729 exit when Pctr = 0 3730 and then (Tref (Sref .. Sref + 1) = ".." 3731 or else 3732 Tref (Sref .. Sref + 2) = " .."); 3733 3734 -- Quit if we have hit EOF character, something wrong 3735 3736 if Tref (Sref) = EOF then 3737 return; 3738 end if; 3739 3740 -- String literals are too much of a pain to handle 3741 3742 if Tref (Sref) = '"' or else Tref (Sref) = '%' then 3743 return; 3744 end if; 3745 3746 -- If we have a 'Range reference, then this is a case 3747 -- where we cannot easily give a replacement. Don't try. 3748 3749 if Tref (Sref .. Sref + 4) = "range" 3750 and then Tref (Sref - 1) < 'A' 3751 and then Tref (Sref + 5) < 'A' 3752 then 3753 return; 3754 end if; 3755 3756 -- Else store next character 3757 3758 Error_Msg_Strlen := Error_Msg_Strlen + 1; 3759 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref); 3760 Sref := Sref + 1; 3761 3762 -- If we get more than 40 characters then the expression 3763 -- is too long to copy, or something has gone wrong. In 3764 -- either case, just skip the attempt at a suggested fix. 3765 3766 if Error_Msg_Strlen > 40 then 3767 return; 3768 end if; 3769 end loop; 3770 end; 3771 3772 -- Replacement subscript is now in string buffer 3773 3774 Error_Msg_FE -- CODEFIX 3775 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent); 3776 end if; 3777 3778 -- Case where subscript is of the form X'Length 3779 3780 elsif Length_Reference (X) then 3781 Warn1; 3782 Error_Msg_Node_2 := Ent; 3783 Error_Msg_FE 3784 ("\?w?suggest replacement of `&''Length` by `&''Last`", 3785 X, Ent); 3786 3787 -- Case where subscript is of the form X'Length - expression 3788 3789 elsif Nkind (X) = N_Op_Subtract 3790 and then Length_Reference (Left_Opnd (X)) 3791 then 3792 Warn1; 3793 Error_Msg_Node_2 := Ent; 3794 Error_Msg_FE 3795 ("\?w?suggest replacement of `&''Length` by `&''Last`", 3796 Left_Opnd (X), Ent); 3797 end if; 3798 end Test_Suspicious_Index; 3799 3800 -- Start of processing for Warn_On_Suspicious_Index 3801 3802 begin 3803 -- Only process if warnings activated 3804 3805 if Warn_On_Assumed_Low_Bound then 3806 3807 -- Test if array is simple entity name 3808 3809 if Is_Entity_Name (Name) then 3810 3811 -- Test if array is parameter of unconstrained string type 3812 3813 Ent := Entity (Name); 3814 Typ := Etype (Ent); 3815 3816 if Is_Formal (Ent) 3817 and then Is_Suspicious_Type (Typ) 3818 and then not Low_Bound_Tested (Ent) 3819 then 3820 Test_Suspicious_Index; 3821 end if; 3822 end if; 3823 end if; 3824 end Warn_On_Suspicious_Index; 3825 3826 -------------------------------------- 3827 -- Warn_On_Unassigned_Out_Parameter -- 3828 -------------------------------------- 3829 3830 procedure Warn_On_Unassigned_Out_Parameter 3831 (Return_Node : Node_Id; 3832 Scope_Id : Entity_Id) 3833 is 3834 Form : Entity_Id; 3835 Form2 : Entity_Id; 3836 3837 begin 3838 -- Ignore if procedure or return statement does not come from source 3839 3840 if not Comes_From_Source (Scope_Id) 3841 or else not Comes_From_Source (Return_Node) 3842 then 3843 return; 3844 end if; 3845 3846 -- Loop through formals 3847 3848 Form := First_Formal (Scope_Id); 3849 while Present (Form) loop 3850 3851 -- We are only interested in OUT parameters that come from source 3852 -- and are never set in the source, and furthermore only in scalars 3853 -- since non-scalars generate too many false positives. 3854 3855 if Ekind (Form) = E_Out_Parameter 3856 and then Never_Set_In_Source_Check_Spec (Form) 3857 and then Is_Scalar_Type (Etype (Form)) 3858 and then not Present (Unset_Reference (Form)) 3859 then 3860 -- Before we issue the warning, an add ad hoc defence against the 3861 -- most common case of false positives with this warning which is 3862 -- the case where there is a Boolean OUT parameter that has been 3863 -- set, and whose meaning is "ignore the values of the other 3864 -- parameters". We can't of course reliably tell this case at 3865 -- compile time, but the following test kills a lot of false 3866 -- positives, without generating a significant number of false 3867 -- negatives (missed real warnings). 3868 3869 Form2 := First_Formal (Scope_Id); 3870 while Present (Form2) loop 3871 if Ekind (Form2) = E_Out_Parameter 3872 and then Root_Type (Etype (Form2)) = Standard_Boolean 3873 and then not Never_Set_In_Source_Check_Spec (Form2) 3874 then 3875 return; 3876 end if; 3877 3878 Next_Formal (Form2); 3879 end loop; 3880 3881 -- Here all conditions are met, record possible unset reference 3882 3883 Set_Unset_Reference (Form, Return_Node); 3884 end if; 3885 3886 Next_Formal (Form); 3887 end loop; 3888 end Warn_On_Unassigned_Out_Parameter; 3889 3890 --------------------------------- 3891 -- Warn_On_Unreferenced_Entity -- 3892 --------------------------------- 3893 3894 procedure Warn_On_Unreferenced_Entity 3895 (Spec_E : Entity_Id; 3896 Body_E : Entity_Id := Empty) 3897 is 3898 E : Entity_Id := Spec_E; 3899 3900 begin 3901 if not Referenced_Check_Spec (E) 3902 and then not Has_Pragma_Unreferenced_Check_Spec (E) 3903 and then not Warnings_Off_Check_Spec (E) 3904 and then not Is_Junk_Name (Chars (Spec_E)) 3905 then 3906 case Ekind (E) is 3907 when E_Variable => 3908 3909 -- Case of variable that is assigned but not read. We suppress 3910 -- the message if the variable is volatile, has an address 3911 -- clause, is aliased, or is a renaming, or is imported. 3912 3913 if Referenced_As_LHS_Check_Spec (E) 3914 and then No (Address_Clause (E)) 3915 and then not Is_Volatile (E) 3916 then 3917 if Warn_On_Modified_Unread 3918 and then not Is_Imported (E) 3919 and then not Is_Aliased (E) 3920 and then No (Renamed_Object (E)) 3921 then 3922 if not Has_Pragma_Unmodified_Check_Spec (E) then 3923 Error_Msg_N -- CODEFIX 3924 ("?u?variable & is assigned but never read!", E); 3925 end if; 3926 3927 Set_Last_Assignment (E, Empty); 3928 end if; 3929 3930 -- Normal case of neither assigned nor read (exclude variables 3931 -- referenced as out parameters, since we already generated 3932 -- appropriate warnings at the call point in this case). 3933 3934 elsif not Referenced_As_Out_Parameter (E) then 3935 3936 -- We suppress the message for types for which a valid 3937 -- pragma Unreferenced_Objects has been given, otherwise 3938 -- we go ahead and give the message. 3939 3940 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then 3941 3942 -- Distinguish renamed case in message 3943 3944 if Present (Renamed_Object (E)) 3945 and then Comes_From_Source (Renamed_Object (E)) 3946 then 3947 Error_Msg_N -- CODEFIX 3948 ("?u?renamed variable & is not referenced!", E); 3949 else 3950 Error_Msg_N -- CODEFIX 3951 ("?u?variable & is not referenced!", E); 3952 end if; 3953 end if; 3954 end if; 3955 3956 when E_Constant => 3957 if Present (Renamed_Object (E)) 3958 and then Comes_From_Source (Renamed_Object (E)) 3959 then 3960 Error_Msg_N -- CODEFIX 3961 ("?u?renamed constant & is not referenced!", E); 3962 else 3963 Error_Msg_N -- CODEFIX 3964 ("?u?constant & is not referenced!", E); 3965 end if; 3966 3967 when E_In_Parameter | 3968 E_In_Out_Parameter => 3969 3970 -- Do not emit message for formals of a renaming, because 3971 -- they are never referenced explicitly. 3972 3973 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /= 3974 N_Subprogram_Renaming_Declaration 3975 then 3976 -- Suppress this message for an IN OUT parameter of a 3977 -- non-scalar type, since it is normal to have only an 3978 -- assignment in such a case. 3979 3980 if Ekind (E) = E_In_Parameter 3981 or else not Referenced_As_LHS_Check_Spec (E) 3982 or else Is_Scalar_Type (Etype (E)) 3983 then 3984 if Present (Body_E) then 3985 E := Body_E; 3986 end if; 3987 3988 if not Is_Trivial_Subprogram (Scope (E)) then 3989 Error_Msg_NE -- CODEFIX 3990 ("?u?formal parameter & is not referenced!", 3991 E, Spec_E); 3992 end if; 3993 end if; 3994 end if; 3995 3996 when E_Out_Parameter => 3997 null; 3998 3999 when E_Discriminant => 4000 Error_Msg_N ("?u?discriminant & is not referenced!", E); 4001 4002 when E_Named_Integer | 4003 E_Named_Real => 4004 Error_Msg_N -- CODEFIX 4005 ("?u?named number & is not referenced!", E); 4006 4007 when Formal_Object_Kind => 4008 Error_Msg_N -- CODEFIX 4009 ("?u?formal object & is not referenced!", E); 4010 4011 when E_Enumeration_Literal => 4012 Error_Msg_N -- CODEFIX 4013 ("?u?literal & is not referenced!", E); 4014 4015 when E_Function => 4016 Error_Msg_N -- CODEFIX 4017 ("?u?function & is not referenced!", E); 4018 4019 when E_Procedure => 4020 Error_Msg_N -- CODEFIX 4021 ("?u?procedure & is not referenced!", E); 4022 4023 when E_Package => 4024 Error_Msg_N -- CODEFIX 4025 ("?u?package & is not referenced!", E); 4026 4027 when E_Exception => 4028 Error_Msg_N -- CODEFIX 4029 ("?u?exception & is not referenced!", E); 4030 4031 when E_Label => 4032 Error_Msg_N -- CODEFIX 4033 ("?u?label & is not referenced!", E); 4034 4035 when E_Generic_Procedure => 4036 Error_Msg_N -- CODEFIX 4037 ("?u?generic procedure & is never instantiated!", E); 4038 4039 when E_Generic_Function => 4040 Error_Msg_N -- CODEFIX 4041 ("?u?generic function & is never instantiated!", E); 4042 4043 when Type_Kind => 4044 Error_Msg_N -- CODEFIX 4045 ("?u?type & is not referenced!", E); 4046 4047 when others => 4048 Error_Msg_N -- CODEFIX 4049 ("?u?& is not referenced!", E); 4050 end case; 4051 4052 -- Kill warnings on the entity on which the message has been posted 4053 4054 Set_Warnings_Off (E); 4055 end if; 4056 end Warn_On_Unreferenced_Entity; 4057 4058 -------------------------------- 4059 -- Warn_On_Useless_Assignment -- 4060 -------------------------------- 4061 4062 procedure Warn_On_Useless_Assignment 4063 (Ent : Entity_Id; 4064 N : Node_Id := Empty) 4065 is 4066 P : Node_Id; 4067 X : Node_Id; 4068 4069 function Check_Ref (N : Node_Id) return Traverse_Result; 4070 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to 4071 -- the entity in question is found. 4072 4073 function Test_No_Refs is new Traverse_Func (Check_Ref); 4074 4075 --------------- 4076 -- Check_Ref -- 4077 --------------- 4078 4079 function Check_Ref (N : Node_Id) return Traverse_Result is 4080 begin 4081 -- Check reference to our identifier. We use name equality here 4082 -- because the exception handlers have not yet been analyzed. This 4083 -- is not quite right, but it really does not matter that we fail 4084 -- to output the warning in some obscure cases of name clashes. 4085 4086 if Nkind (N) = N_Identifier 4087 and then Chars (N) = Chars (Ent) 4088 then 4089 return Abandon; 4090 else 4091 return OK; 4092 end if; 4093 end Check_Ref; 4094 4095 -- Start of processing for Warn_On_Useless_Assignment 4096 4097 begin 4098 -- Check if this is a case we want to warn on, a scalar or access 4099 -- variable with the last assignment field set, with warnings enabled, 4100 -- and which is not imported or exported. We also check that it is OK 4101 -- to capture the value. We are not going to capture any value, but 4102 -- the warning message depends on the same kind of conditions. 4103 4104 if Is_Assignable (Ent) 4105 and then not Is_Return_Object (Ent) 4106 and then Present (Last_Assignment (Ent)) 4107 and then not Is_Imported (Ent) 4108 and then not Is_Exported (Ent) 4109 and then Safe_To_Capture_Value (N, Ent) 4110 and then not Has_Pragma_Unreferenced_Check_Spec (Ent) 4111 and then not Is_Junk_Name (Chars (Ent)) 4112 then 4113 -- Before we issue the message, check covering exception handlers. 4114 -- Search up tree for enclosing statement sequences and handlers. 4115 4116 P := Parent (Last_Assignment (Ent)); 4117 while Present (P) loop 4118 4119 -- Something is really wrong if we don't find a handled statement 4120 -- sequence, so just suppress the warning. 4121 4122 if No (P) then 4123 Set_Last_Assignment (Ent, Empty); 4124 return; 4125 4126 -- When we hit a package/subprogram body, issue warning and exit 4127 4128 elsif Nkind (P) = N_Subprogram_Body 4129 or else Nkind (P) = N_Package_Body 4130 then 4131 -- Case of assigned value never referenced 4132 4133 if No (N) then 4134 declare 4135 LA : constant Node_Id := Last_Assignment (Ent); 4136 4137 begin 4138 -- Don't give this for OUT and IN OUT formals, since 4139 -- clearly caller may reference the assigned value. Also 4140 -- never give such warnings for internal variables. 4141 4142 if Ekind (Ent) = E_Variable 4143 and then not Is_Internal_Name (Chars (Ent)) 4144 then 4145 -- Give appropriate message, distinguishing between 4146 -- assignment statements and out parameters. 4147 4148 if Nkind_In (Parent (LA), N_Procedure_Call_Statement, 4149 N_Parameter_Association) 4150 then 4151 Error_Msg_NE 4152 ("?m?& modified by call, but value never " 4153 & "referenced", LA, Ent); 4154 4155 else 4156 Error_Msg_NE -- CODEFIX 4157 ("?m?useless assignment to&, value never " 4158 & "referenced!", LA, Ent); 4159 end if; 4160 end if; 4161 end; 4162 4163 -- Case of assigned value overwritten 4164 4165 else 4166 declare 4167 LA : constant Node_Id := Last_Assignment (Ent); 4168 4169 begin 4170 Error_Msg_Sloc := Sloc (N); 4171 4172 -- Give appropriate message, distinguishing between 4173 -- assignment statements and out parameters. 4174 4175 if Nkind_In (Parent (LA), N_Procedure_Call_Statement, 4176 N_Parameter_Association) 4177 then 4178 Error_Msg_NE 4179 ("?m?& modified by call, but value overwritten #!", 4180 LA, Ent); 4181 else 4182 Error_Msg_NE -- CODEFIX 4183 ("?m?useless assignment to&, value overwritten #!", 4184 LA, Ent); 4185 end if; 4186 end; 4187 end if; 4188 4189 -- Clear last assignment indication and we are done 4190 4191 Set_Last_Assignment (Ent, Empty); 4192 return; 4193 4194 -- Enclosing handled sequence of statements 4195 4196 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then 4197 4198 -- Check exception handlers present 4199 4200 if Present (Exception_Handlers (P)) then 4201 4202 -- If we are not at the top level, we regard an inner 4203 -- exception handler as a decisive indicator that we should 4204 -- not generate the warning, since the variable in question 4205 -- may be accessed after an exception in the outer block. 4206 4207 if Nkind (Parent (P)) /= N_Subprogram_Body 4208 and then Nkind (Parent (P)) /= N_Package_Body 4209 then 4210 Set_Last_Assignment (Ent, Empty); 4211 return; 4212 4213 -- Otherwise we are at the outer level. An exception 4214 -- handler is significant only if it references the 4215 -- variable in question, or if the entity in question 4216 -- is an OUT or IN OUT parameter, which which case 4217 -- the caller can reference it after the exception 4218 -- handler completes. 4219 4220 else 4221 if Is_Formal (Ent) then 4222 Set_Last_Assignment (Ent, Empty); 4223 return; 4224 4225 else 4226 X := First (Exception_Handlers (P)); 4227 while Present (X) loop 4228 if Test_No_Refs (X) = Abandon then 4229 Set_Last_Assignment (Ent, Empty); 4230 return; 4231 end if; 4232 4233 X := Next (X); 4234 end loop; 4235 end if; 4236 end if; 4237 end if; 4238 end if; 4239 4240 P := Parent (P); 4241 end loop; 4242 end if; 4243 end Warn_On_Useless_Assignment; 4244 4245 --------------------------------- 4246 -- Warn_On_Useless_Assignments -- 4247 --------------------------------- 4248 4249 procedure Warn_On_Useless_Assignments (E : Entity_Id) is 4250 Ent : Entity_Id; 4251 4252 begin 4253 Process_Deferred_References; 4254 4255 if Warn_On_Modified_Unread 4256 and then In_Extended_Main_Source_Unit (E) 4257 then 4258 Ent := First_Entity (E); 4259 while Present (Ent) loop 4260 Warn_On_Useless_Assignment (Ent); 4261 Next_Entity (Ent); 4262 end loop; 4263 end if; 4264 end Warn_On_Useless_Assignments; 4265 4266 ----------------------------- 4267 -- Warnings_Off_Check_Spec -- 4268 ----------------------------- 4269 4270 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is 4271 begin 4272 if Is_Formal (E) and then Present (Spec_Entity (E)) then 4273 4274 -- Note: use of OR here instead of OR ELSE is deliberate, we want 4275 -- to mess with flags on both entities. 4276 4277 return Has_Warnings_Off (E) 4278 or 4279 Has_Warnings_Off (Spec_Entity (E)); 4280 4281 else 4282 return Has_Warnings_Off (E); 4283 end if; 4284 end Warnings_Off_Check_Spec; 4285 4286end Sem_Warn; 4287