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) 1999-2012, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26with Atree; use Atree; 27with Debug; use Debug; 28with Einfo; use Einfo; 29with Errout; use Errout; 30with Exp_Code; use Exp_Code; 31with Fname; use Fname; 32with Lib; use Lib; 33with Namet; use Namet; 34with Nlists; use Nlists; 35with Opt; use Opt; 36with Par_SCO; use Par_SCO; 37with Rtsfind; use Rtsfind; 38with Sem; use Sem; 39with Sem_Ch8; use Sem_Ch8; 40with Sem_Aux; use Sem_Aux; 41with Sem_Eval; use Sem_Eval; 42with Sem_Util; use Sem_Util; 43with Sinfo; use Sinfo; 44with Sinput; use Sinput; 45with Snames; use Snames; 46with Stand; use Stand; 47with Stringt; use Stringt; 48with Uintp; use Uintp; 49 50package body Sem_Warn is 51 52 -- The following table collects Id's of entities that are potentially 53 -- unreferenced. See Check_Unset_Reference for further details. 54 -- ??? Check_Unset_Reference has zero information about this table. 55 56 package Unreferenced_Entities is new Table.Table ( 57 Table_Component_Type => Entity_Id, 58 Table_Index_Type => Nat, 59 Table_Low_Bound => 1, 60 Table_Initial => Alloc.Unreferenced_Entities_Initial, 61 Table_Increment => Alloc.Unreferenced_Entities_Increment, 62 Table_Name => "Unreferenced_Entities"); 63 64 -- The following table collects potential warnings for IN OUT parameters 65 -- that are referenced but not modified. These warnings are processed when 66 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings. 67 -- The reason that we defer output of these messages is that we want to 68 -- detect the case where the relevant procedure is used as a generic actual 69 -- in an instantiation, since we suppress the warnings in this case. The 70 -- flag Used_As_Generic_Actual will be set in this case, but only at the 71 -- point of usage. Similarly, we suppress the message if the address of the 72 -- procedure is taken, where the flag Address_Taken may be set later. 73 74 package In_Out_Warnings is new Table.Table ( 75 Table_Component_Type => Entity_Id, 76 Table_Index_Type => Nat, 77 Table_Low_Bound => 1, 78 Table_Initial => Alloc.In_Out_Warnings_Initial, 79 Table_Increment => Alloc.In_Out_Warnings_Increment, 80 Table_Name => "In_Out_Warnings"); 81 82 -------------------------------------------------------- 83 -- Handling of Warnings Off, Unmodified, Unreferenced -- 84 -------------------------------------------------------- 85 86 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must 87 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and 88 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo. 89 90 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary 91 -- warnings off pragma) mode, i.e. to avoid false negatives, the code 92 -- must follow some important rules. 93 94 -- Call these functions as late as possible, after completing all other 95 -- tests, just before the warnings is given. For example, don't write: 96 97 -- if not Has_Warnings_Off (E) 98 -- and then some-other-predicate-on-E then .. 99 100 -- Instead the following is preferred 101 102 -- if some-other-predicate-on-E 103 -- and then Has_Warnings_Off (E) 104 105 -- This way if some-other-predicate is false, we avoid a false indication 106 -- that a Warnings (Off, E) pragma was useful in preventing a warning. 107 108 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or 109 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the 110 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record 111 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In 112 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off, 113 -- and so a subsequent test is not needed anyway (though it is harmless). 114 115 ----------------------- 116 -- Local Subprograms -- 117 ----------------------- 118 119 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean; 120 -- This returns true if the entity E is declared within a generic package. 121 -- The point of this is to detect variables which are not assigned within 122 -- the generic, but might be assigned outside the package for any given 123 -- instance. These are cases where we leave the warnings to be posted for 124 -- the instance, when we will know more. 125 126 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id; 127 -- If E is a parameter entity for a subprogram body, then this function 128 -- returns the corresponding spec entity, if not, E is returned unchanged. 129 130 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean; 131 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal, 132 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is 133 -- a body formal, the setting of the flag in the corresponding spec is 134 -- also checked (and True returned if either flag is True). 135 136 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean; 137 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal, 138 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is 139 -- a body formal, the setting of the flag in the corresponding spec is 140 -- also checked (and True returned if either flag is True). 141 142 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean; 143 -- Tests Never_Set_In_Source status for entity E. If E is not a formal, 144 -- this is simply the setting of the flag Never_Set_In_Source. If E is 145 -- a body formal, the setting of the flag in the corresponding spec is 146 -- also checked (and False returned if either flag is False). 147 148 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean; 149 -- This function traverses the expression tree represented by the node N 150 -- and determines if any sub-operand is a reference to an entity for which 151 -- the Warnings_Off flag is set. True is returned if such an entity is 152 -- encountered, and False otherwise. 153 154 function Referenced_Check_Spec (E : Entity_Id) return Boolean; 155 -- Tests Referenced status for entity E. If E is not a formal, this is 156 -- simply the setting of the flag Referenced. If E is a body formal, the 157 -- setting of the flag in the corresponding spec is also checked (and True 158 -- returned if either flag is True). 159 160 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean; 161 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this 162 -- is simply the setting of the flag Referenced_As_LHS. If E is a body 163 -- formal, the setting of the flag in the corresponding spec is also 164 -- checked (and True returned if either flag is True). 165 166 function Referenced_As_Out_Parameter_Check_Spec 167 (E : Entity_Id) return Boolean; 168 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a 169 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E 170 -- is a body formal, the setting of the flag in the corresponding spec is 171 -- also checked (and True returned if either flag is True). 172 173 procedure Warn_On_Unreferenced_Entity 174 (Spec_E : Entity_Id; 175 Body_E : Entity_Id := Empty); 176 -- Output warnings for unreferenced entity E. For the case of an entry 177 -- formal, Body_E is the corresponding body entity for a particular 178 -- accept statement, and the message is posted on Body_E. In all other 179 -- cases, Body_E is ignored and must be Empty. 180 181 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean; 182 -- Returns True if Warnings_Off is set for the entity E or (in the case 183 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity. 184 185 -------------------------- 186 -- Check_Code_Statement -- 187 -------------------------- 188 189 procedure Check_Code_Statement (N : Node_Id) is 190 begin 191 -- If volatile, nothing to worry about 192 193 if Is_Asm_Volatile (N) then 194 return; 195 end if; 196 197 -- Warn if no input or no output 198 199 Setup_Asm_Inputs (N); 200 201 if No (Asm_Input_Value) then 202 Error_Msg_F 203 ("??code statement with no inputs should usually be Volatile!", N); 204 return; 205 end if; 206 207 Setup_Asm_Outputs (N); 208 209 if No (Asm_Output_Variable) then 210 Error_Msg_F 211 ("??code statement with no outputs should usually be Volatile!", N); 212 return; 213 end if; 214 end Check_Code_Statement; 215 216 --------------------------------- 217 -- Check_Infinite_Loop_Warning -- 218 --------------------------------- 219 220 -- The case we look for is a while loop which tests a local variable, where 221 -- there is no obvious direct or possible indirect update of the variable 222 -- within the body of the loop. 223 224 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is 225 Expression : Node_Id := Empty; 226 -- Set to WHILE or EXIT WHEN condition to be tested 227 228 Ref : Node_Id := Empty; 229 -- Reference in Expression to variable that might not be modified 230 -- in loop, indicating a possible infinite loop. 231 232 Var : Entity_Id := Empty; 233 -- Corresponding entity (entity of Ref) 234 235 Function_Call_Found : Boolean := False; 236 -- True if Find_Var found a function call in the condition 237 238 procedure Find_Var (N : Node_Id); 239 -- Inspect condition to see if it depends on a single entity reference. 240 -- If so, Ref is set to point to the reference node, and Var is set to 241 -- the referenced Entity. 242 243 function Has_Indirection (T : Entity_Id) return Boolean; 244 -- If the controlling variable is an access type, or is a record type 245 -- with access components, assume that it is changed indirectly and 246 -- suppress the warning. As a concession to low-level programming, in 247 -- particular within Declib, we also suppress warnings on a record 248 -- type that contains components of type Address or Short_Address. 249 250 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean; 251 -- Given an entity name, see if the name appears to have something to 252 -- do with I/O or network stuff, and if so, return True. Used to kill 253 -- some false positives on a heuristic basis that such functions will 254 -- likely have some strange side effect dependencies. A rather funny 255 -- kludge, but warning messages are in the heuristics business. 256 257 function Test_Ref (N : Node_Id) return Traverse_Result; 258 -- Test for reference to variable in question. Returns Abandon if 259 -- matching reference found. Used in instantiation of No_Ref_Found. 260 261 function No_Ref_Found is new Traverse_Func (Test_Ref); 262 -- Function to traverse body of procedure. Returns Abandon if matching 263 -- reference found. 264 265 -------------- 266 -- Find_Var -- 267 -------------- 268 269 procedure Find_Var (N : Node_Id) is 270 begin 271 -- Condition is a direct variable reference 272 273 if Is_Entity_Name (N) then 274 Ref := N; 275 Var := Entity (Ref); 276 277 -- Case of condition is a comparison with compile time known value 278 279 elsif Nkind (N) in N_Op_Compare then 280 if Compile_Time_Known_Value (Right_Opnd (N)) then 281 Find_Var (Left_Opnd (N)); 282 283 elsif Compile_Time_Known_Value (Left_Opnd (N)) then 284 Find_Var (Right_Opnd (N)); 285 286 -- Ignore any other comparison 287 288 else 289 return; 290 end if; 291 292 -- If condition is a negation, check its operand 293 294 elsif Nkind (N) = N_Op_Not then 295 Find_Var (Right_Opnd (N)); 296 297 -- Case of condition is function call 298 299 elsif Nkind (N) = N_Function_Call then 300 301 Function_Call_Found := True; 302 303 -- Forget it if function name is not entity, who knows what 304 -- we might be calling? 305 306 if not Is_Entity_Name (Name (N)) then 307 return; 308 309 -- Forget it if function name is suspicious. A strange test 310 -- but warning generation is in the heuristics business! 311 312 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then 313 return; 314 315 -- Forget it if warnings are suppressed on function entity 316 317 elsif Has_Warnings_Off (Entity (Name (N))) then 318 return; 319 end if; 320 321 -- OK, see if we have one argument 322 323 declare 324 PA : constant List_Id := Parameter_Associations (N); 325 326 begin 327 -- One argument, so check the argument 328 329 if Present (PA) 330 and then List_Length (PA) = 1 331 then 332 if Nkind (First (PA)) = N_Parameter_Association then 333 Find_Var (Explicit_Actual_Parameter (First (PA))); 334 else 335 Find_Var (First (PA)); 336 end if; 337 338 -- Not one argument 339 340 else 341 return; 342 end if; 343 end; 344 345 -- Any other kind of node is not something we warn for 346 347 else 348 return; 349 end if; 350 end Find_Var; 351 352 --------------------- 353 -- Has_Indirection -- 354 --------------------- 355 356 function Has_Indirection (T : Entity_Id) return Boolean is 357 Comp : Entity_Id; 358 Rec : Entity_Id; 359 360 begin 361 if Is_Access_Type (T) then 362 return True; 363 364 elsif Is_Private_Type (T) 365 and then Present (Full_View (T)) 366 and then Is_Access_Type (Full_View (T)) 367 then 368 return True; 369 370 elsif Is_Record_Type (T) then 371 Rec := T; 372 373 elsif Is_Private_Type (T) 374 and then Present (Full_View (T)) 375 and then Is_Record_Type (Full_View (T)) 376 then 377 Rec := Full_View (T); 378 else 379 return False; 380 end if; 381 382 Comp := First_Component (Rec); 383 while Present (Comp) loop 384 if Is_Access_Type (Etype (Comp)) 385 or else Is_Descendent_Of_Address (Etype (Comp)) 386 then 387 return True; 388 end if; 389 390 Next_Component (Comp); 391 end loop; 392 393 return False; 394 end Has_Indirection; 395 396 --------------------------------- 397 -- Is_Suspicious_Function_Name -- 398 --------------------------------- 399 400 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is 401 S : Entity_Id; 402 403 function Substring_Present (S : String) return Boolean; 404 -- Returns True if name buffer has given string delimited by non- 405 -- alphabetic characters or by end of string. S is lower case. 406 407 ----------------------- 408 -- Substring_Present -- 409 ----------------------- 410 411 function Substring_Present (S : String) return Boolean is 412 Len : constant Natural := S'Length; 413 414 begin 415 for J in 1 .. Name_Len - (Len - 1) loop 416 if Name_Buffer (J .. J + (Len - 1)) = S 417 and then 418 (J = 1 419 or else Name_Buffer (J - 1) not in 'a' .. 'z') 420 and then 421 (J + Len > Name_Len 422 or else Name_Buffer (J + Len) not in 'a' .. 'z') 423 then 424 return True; 425 end if; 426 end loop; 427 428 return False; 429 end Substring_Present; 430 431 -- Start of processing for Is_Suspicious_Function_Name 432 433 begin 434 S := E; 435 while Present (S) and then S /= Standard_Standard loop 436 Get_Name_String (Chars (S)); 437 438 if Substring_Present ("io") 439 or else Substring_Present ("file") 440 or else Substring_Present ("network") 441 then 442 return True; 443 else 444 S := Scope (S); 445 end if; 446 end loop; 447 448 return False; 449 end Is_Suspicious_Function_Name; 450 451 -------------- 452 -- Test_Ref -- 453 -------------- 454 455 function Test_Ref (N : Node_Id) return Traverse_Result is 456 begin 457 -- Waste of time to look at the expression we are testing 458 459 if N = Expression then 460 return Skip; 461 462 -- Direct reference to variable in question 463 464 elsif Is_Entity_Name (N) 465 and then Present (Entity (N)) 466 and then Entity (N) = Var 467 then 468 -- If this is an lvalue, then definitely abandon, since 469 -- this could be a direct modification of the variable. 470 471 if May_Be_Lvalue (N) then 472 return Abandon; 473 end if; 474 475 -- If the condition contains a function call, we consider it may 476 -- be modified by side-effects from a procedure call. Otherwise, 477 -- we consider the condition may not be modified, although that 478 -- might happen if Variable is itself a by-reference parameter, 479 -- and the procedure called modifies the global object referred to 480 -- by Variable, but we actually prefer to issue a warning in this 481 -- odd case. Note that the case where the procedure called has 482 -- visibility over Variable is treated in another case below. 483 484 if Function_Call_Found then 485 declare 486 P : Node_Id; 487 488 begin 489 P := N; 490 loop 491 P := Parent (P); 492 exit when P = Loop_Statement; 493 494 -- Abandon if at procedure call, or something strange is 495 -- going on (perhaps a node with no parent that should 496 -- have one but does not?) As always, for a warning we 497 -- prefer to just abandon the warning than get into the 498 -- business of complaining about the tree structure here! 499 500 if No (P) 501 or else Nkind (P) = N_Procedure_Call_Statement 502 then 503 return Abandon; 504 end if; 505 end loop; 506 end; 507 end if; 508 509 -- Reference to variable renaming variable in question 510 511 elsif Is_Entity_Name (N) 512 and then Present (Entity (N)) 513 and then Ekind (Entity (N)) = E_Variable 514 and then Present (Renamed_Object (Entity (N))) 515 and then Is_Entity_Name (Renamed_Object (Entity (N))) 516 and then Entity (Renamed_Object (Entity (N))) = Var 517 and then May_Be_Lvalue (N) 518 then 519 return Abandon; 520 521 -- Call to subprogram 522 523 elsif Nkind (N) in N_Subprogram_Call then 524 525 -- If subprogram is within the scope of the entity we are dealing 526 -- with as the loop variable, then it could modify this parameter, 527 -- so we abandon in this case. In the case of a subprogram that is 528 -- not an entity we also abandon. The check for no entity being 529 -- present is a defense against previous errors. 530 531 if not Is_Entity_Name (Name (N)) 532 or else No (Entity (Name (N))) 533 or else Scope_Within (Entity (Name (N)), Scope (Var)) 534 then 535 return Abandon; 536 end if; 537 538 -- If any of the arguments are of type access to subprogram, then 539 -- we may have funny side effects, so no warning in this case. 540 541 declare 542 Actual : Node_Id; 543 begin 544 Actual := First_Actual (N); 545 while Present (Actual) loop 546 if Is_Access_Subprogram_Type (Etype (Actual)) then 547 return Abandon; 548 else 549 Next_Actual (Actual); 550 end if; 551 end loop; 552 end; 553 554 -- Declaration of the variable in question 555 556 elsif Nkind (N) = N_Object_Declaration 557 and then Defining_Identifier (N) = Var 558 then 559 return Abandon; 560 end if; 561 562 -- All OK, continue scan 563 564 return OK; 565 end Test_Ref; 566 567 -- Start of processing for Check_Infinite_Loop_Warning 568 569 begin 570 -- Skip processing if debug flag gnatd.w is set 571 572 if Debug_Flag_Dot_W then 573 return; 574 end if; 575 576 -- Deal with Iteration scheme present 577 578 declare 579 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement); 580 581 begin 582 if Present (Iter) then 583 584 -- While iteration 585 586 if Present (Condition (Iter)) then 587 588 -- Skip processing for while iteration with conditions actions, 589 -- since they make it too complicated to get the warning right. 590 591 if Present (Condition_Actions (Iter)) then 592 return; 593 end if; 594 595 -- Capture WHILE condition 596 597 Expression := Condition (Iter); 598 599 -- For iteration, do not process, since loop will always terminate 600 601 elsif Present (Loop_Parameter_Specification (Iter)) then 602 return; 603 end if; 604 end if; 605 end; 606 607 -- Check chain of EXIT statements, we only process loops that have a 608 -- single exit condition (either a single EXIT WHEN statement, or a 609 -- WHILE loop not containing any EXIT WHEN statements). 610 611 declare 612 Ident : constant Node_Id := Identifier (Loop_Statement); 613 Exit_Stmt : Node_Id; 614 615 begin 616 -- If we don't have a proper chain set, ignore call entirely. This 617 -- happens because of previous errors. 618 619 if No (Entity (Ident)) 620 or else Ekind (Entity (Ident)) /= E_Loop 621 then 622 Check_Error_Detected; 623 return; 624 end if; 625 626 -- Otherwise prepare to scan list of EXIT statements 627 628 Exit_Stmt := First_Exit_Statement (Entity (Ident)); 629 while Present (Exit_Stmt) loop 630 631 -- Check for EXIT WHEN 632 633 if Present (Condition (Exit_Stmt)) then 634 635 -- Quit processing if EXIT WHEN in WHILE loop, or more than 636 -- one EXIT WHEN statement present in the loop. 637 638 if Present (Expression) then 639 return; 640 641 -- Otherwise capture condition from EXIT WHEN statement 642 643 else 644 Expression := Condition (Exit_Stmt); 645 end if; 646 end if; 647 648 Exit_Stmt := Next_Exit_Statement (Exit_Stmt); 649 end loop; 650 end; 651 652 -- Return if no condition to test 653 654 if No (Expression) then 655 return; 656 end if; 657 658 -- Initial conditions met, see if condition is of right form 659 660 Find_Var (Expression); 661 662 -- Nothing to do if local variable from source not found. If it's a 663 -- renaming, it is probably renaming something too complicated to deal 664 -- with here. 665 666 if No (Var) 667 or else Ekind (Var) /= E_Variable 668 or else Is_Library_Level_Entity (Var) 669 or else not Comes_From_Source (Var) 670 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration 671 then 672 return; 673 674 -- Nothing to do if there is some indirection involved (assume that the 675 -- designated variable might be modified in some way we don't see). 676 -- However, if no function call was found, then we don't care about 677 -- indirections, because the condition must be something like "while X 678 -- /= null loop", so we don't care if X.all is modified in the loop. 679 680 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then 681 return; 682 683 -- Same sort of thing for volatile variable, might be modified by 684 -- some other task or by the operating system in some way. 685 686 elsif Is_Volatile (Var) then 687 return; 688 end if; 689 690 -- Filter out case of original statement sequence starting with delay. 691 -- We assume this is a multi-tasking program and that the condition 692 -- is affected by other threads (some kind of busy wait). 693 694 declare 695 Fstm : constant Node_Id := 696 Original_Node (First (Statements (Loop_Statement))); 697 begin 698 if Nkind (Fstm) = N_Delay_Relative_Statement 699 or else Nkind (Fstm) = N_Delay_Until_Statement 700 then 701 return; 702 end if; 703 end; 704 705 -- We have a variable reference of the right form, now we scan the loop 706 -- body to see if it looks like it might not be modified 707 708 if No_Ref_Found (Loop_Statement) = OK then 709 Error_Msg_NE 710 ("??variable& is not modified in loop body!", Ref, Var); 711 Error_Msg_N 712 ("\??possible infinite loop!", Ref); 713 end if; 714 end Check_Infinite_Loop_Warning; 715 716 ---------------------------- 717 -- Check_Low_Bound_Tested -- 718 ---------------------------- 719 720 procedure Check_Low_Bound_Tested (Expr : Node_Id) is 721 begin 722 if Comes_From_Source (Expr) then 723 declare 724 L : constant Node_Id := Left_Opnd (Expr); 725 R : constant Node_Id := Right_Opnd (Expr); 726 begin 727 if Nkind (L) = N_Attribute_Reference 728 and then Attribute_Name (L) = Name_First 729 and then Is_Entity_Name (Prefix (L)) 730 and then Is_Formal (Entity (Prefix (L))) 731 then 732 Set_Low_Bound_Tested (Entity (Prefix (L))); 733 end if; 734 735 if Nkind (R) = N_Attribute_Reference 736 and then Attribute_Name (R) = Name_First 737 and then Is_Entity_Name (Prefix (R)) 738 and then Is_Formal (Entity (Prefix (R))) 739 then 740 Set_Low_Bound_Tested (Entity (Prefix (R))); 741 end if; 742 end; 743 end if; 744 end Check_Low_Bound_Tested; 745 746 ---------------------- 747 -- Check_References -- 748 ---------------------- 749 750 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is 751 E1 : Entity_Id; 752 E1T : Entity_Id; 753 UR : Node_Id; 754 755 function Body_Formal 756 (E : Entity_Id; 757 Accept_Statement : Node_Id) return Entity_Id; 758 -- For an entry formal entity from an entry declaration, find the 759 -- corresponding body formal from the given accept statement. 760 761 function Missing_Subunits return Boolean; 762 -- We suppress warnings when there are missing subunits, because this 763 -- may generate too many false positives: entities in a parent may only 764 -- be referenced in one of the subunits. We make an exception for 765 -- subunits that contain no other stubs. 766 767 procedure Output_Reference_Error (M : String); 768 -- Used to output an error message. Deals with posting the error on the 769 -- body formal in the accept case. 770 771 function Publicly_Referenceable (Ent : Entity_Id) return Boolean; 772 -- This is true if the entity in question is potentially referenceable 773 -- from another unit. This is true for entities in packages that are at 774 -- the library level. 775 776 function Warnings_Off_E1 return Boolean; 777 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T), 778 -- or for the base type of E1T. 779 780 ----------------- 781 -- Body_Formal -- 782 ----------------- 783 784 function Body_Formal 785 (E : Entity_Id; 786 Accept_Statement : Node_Id) return Entity_Id 787 is 788 Body_Param : Node_Id; 789 Body_E : Entity_Id; 790 791 begin 792 -- Loop to find matching parameter in accept statement 793 794 Body_Param := First (Parameter_Specifications (Accept_Statement)); 795 while Present (Body_Param) loop 796 Body_E := Defining_Identifier (Body_Param); 797 798 if Chars (Body_E) = Chars (E) then 799 return Body_E; 800 end if; 801 802 Next (Body_Param); 803 end loop; 804 805 -- Should never fall through, should always find a match 806 807 raise Program_Error; 808 end Body_Formal; 809 810 ---------------------- 811 -- Missing_Subunits -- 812 ---------------------- 813 814 function Missing_Subunits return Boolean is 815 D : Node_Id; 816 817 begin 818 if not Unloaded_Subunits then 819 820 -- Normal compilation, all subunits are present 821 822 return False; 823 824 elsif E /= Main_Unit_Entity then 825 826 -- No warnings on a stub that is not the main unit 827 828 return True; 829 830 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then 831 D := First (Declarations (Unit_Declaration_Node (E))); 832 while Present (D) loop 833 834 -- No warnings if the proper body contains nested stubs 835 836 if Nkind (D) in N_Body_Stub then 837 return True; 838 end if; 839 840 Next (D); 841 end loop; 842 843 return False; 844 845 else 846 -- Missing stubs elsewhere 847 848 return True; 849 end if; 850 end Missing_Subunits; 851 852 ---------------------------- 853 -- Output_Reference_Error -- 854 ---------------------------- 855 856 procedure Output_Reference_Error (M : String) is 857 begin 858 -- Never issue messages for internal names, nor for renamings 859 860 if Is_Internal_Name (Chars (E1)) 861 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration 862 then 863 return; 864 end if; 865 866 -- Don't output message for IN OUT formal unless we have the warning 867 -- flag specifically set. It is a bit odd to distinguish IN OUT 868 -- formals from other cases. This distinction is historical in 869 -- nature. Warnings for IN OUT formals were added fairly late. 870 871 if Ekind (E1) = E_In_Out_Parameter 872 and then not Check_Unreferenced_Formals 873 then 874 return; 875 end if; 876 877 -- Other than accept case, post error on defining identifier 878 879 if No (Anod) then 880 Error_Msg_N (M, E1); 881 882 -- Accept case, find body formal to post the message 883 884 else 885 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1); 886 887 end if; 888 end Output_Reference_Error; 889 890 ---------------------------- 891 -- Publicly_Referenceable -- 892 ---------------------------- 893 894 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is 895 P : Node_Id; 896 Prev : Node_Id; 897 898 begin 899 -- A formal parameter is never referenceable outside the body of its 900 -- subprogram or entry. 901 902 if Is_Formal (Ent) then 903 return False; 904 end if; 905 906 -- Examine parents to look for a library level package spec. But if 907 -- we find a body or block or other similar construct along the way, 908 -- we cannot be referenced. 909 910 Prev := Ent; 911 P := Parent (Ent); 912 loop 913 case Nkind (P) is 914 915 -- If we get to top of tree, then publicly referenceable 916 917 when N_Empty => 918 return True; 919 920 -- If we reach a generic package declaration, then always 921 -- consider this referenceable, since any instantiation will 922 -- have access to the entities in the generic package. Note 923 -- that the package itself may not be instantiated, but then 924 -- we will get a warning for the package entity. 925 926 -- Note that generic formal parameters are themselves not 927 -- publicly referenceable in an instance, and warnings on them 928 -- are useful. 929 930 when N_Generic_Package_Declaration => 931 return 932 not Is_List_Member (Prev) 933 or else List_Containing (Prev) 934 /= Generic_Formal_Declarations (P); 935 936 -- Similarly, the generic formals of a generic subprogram are 937 -- not accessible. 938 939 when N_Generic_Subprogram_Declaration => 940 if Is_List_Member (Prev) 941 and then List_Containing (Prev) = 942 Generic_Formal_Declarations (P) 943 then 944 return False; 945 else 946 P := Parent (P); 947 end if; 948 949 -- If we reach a subprogram body, entity is not referenceable 950 -- unless it is the defining entity of the body. This will 951 -- happen, e.g. when a function is an attribute renaming that 952 -- is rewritten as a body. 953 954 when N_Subprogram_Body => 955 if Ent /= Defining_Entity (P) then 956 return False; 957 else 958 P := Parent (P); 959 end if; 960 961 -- If we reach any other body, definitely not referenceable 962 963 when N_Package_Body | 964 N_Task_Body | 965 N_Entry_Body | 966 N_Protected_Body | 967 N_Block_Statement | 968 N_Subunit => 969 return False; 970 971 -- For all other cases, keep looking up tree 972 973 when others => 974 Prev := P; 975 P := Parent (P); 976 end case; 977 end loop; 978 end Publicly_Referenceable; 979 980 --------------------- 981 -- Warnings_Off_E1 -- 982 --------------------- 983 984 function Warnings_Off_E1 return Boolean is 985 begin 986 return Has_Warnings_Off (E1T) 987 or else Has_Warnings_Off (Base_Type (E1T)) 988 or else Warnings_Off_Check_Spec (E1); 989 end Warnings_Off_E1; 990 991 -- Start of processing for Check_References 992 993 begin 994 -- No messages if warnings are suppressed, or if we have detected any 995 -- real errors so far (this last check avoids junk messages resulting 996 -- from errors, e.g. a subunit that is not loaded). 997 998 if Warning_Mode = Suppress 999 or else Serious_Errors_Detected /= 0 1000 then 1001 return; 1002 end if; 1003 1004 -- We also skip the messages if any subunits were not loaded (see 1005 -- comment in Sem_Ch10 to understand how this is set, and why it is 1006 -- necessary to suppress the warnings in this case). 1007 1008 if Missing_Subunits then 1009 return; 1010 end if; 1011 1012 -- Otherwise loop through entities, looking for suspicious stuff 1013 1014 E1 := First_Entity (E); 1015 while Present (E1) loop 1016 E1T := Etype (E1); 1017 1018 -- We are only interested in source entities. We also don't issue 1019 -- warnings within instances, since the proper place for such 1020 -- warnings is on the template when it is compiled. 1021 1022 if Comes_From_Source (E1) 1023 and then Instantiation_Location (Sloc (E1)) = No_Location 1024 then 1025 -- We are interested in variables and out/in-out parameters, but 1026 -- we exclude protected types, too complicated to worry about. 1027 1028 if Ekind (E1) = E_Variable 1029 or else 1030 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter) 1031 and then not Is_Protected_Type (Current_Scope)) 1032 then 1033 -- Case of an unassigned variable 1034 1035 -- First gather any Unset_Reference indication for E1. In the 1036 -- case of a parameter, it is the Spec_Entity that is relevant. 1037 1038 if Ekind (E1) = E_Out_Parameter 1039 and then Present (Spec_Entity (E1)) 1040 then 1041 UR := Unset_Reference (Spec_Entity (E1)); 1042 else 1043 UR := Unset_Reference (E1); 1044 end if; 1045 1046 -- Special processing for access types 1047 1048 if Present (UR) 1049 and then Is_Access_Type (E1T) 1050 then 1051 -- For access types, the only time we made a UR entry was 1052 -- for a dereference, and so we post the appropriate warning 1053 -- here (note that the dereference may not be explicit in 1054 -- the source, for example in the case of a dispatching call 1055 -- with an anonymous access controlling formal, or of an 1056 -- assignment of a pointer involving discriminant check on 1057 -- the designated object). 1058 1059 if not Warnings_Off_E1 then 1060 Error_Msg_NE ("??& may be null!", UR, E1); 1061 end if; 1062 1063 goto Continue; 1064 1065 -- Case of variable that could be a constant. Note that we 1066 -- never signal such messages for generic package entities, 1067 -- since a given instance could have modifications outside 1068 -- the package. 1069 1070 elsif Warn_On_Constant 1071 and then (Ekind (E1) = E_Variable 1072 and then Has_Initial_Value (E1)) 1073 and then Never_Set_In_Source_Check_Spec (E1) 1074 and then not Address_Taken (E1) 1075 and then not Generic_Package_Spec_Entity (E1) 1076 then 1077 -- A special case, if this variable is volatile and not 1078 -- imported, it is not helpful to tell the programmer 1079 -- to mark the variable as constant, since this would be 1080 -- illegal by virtue of RM C.6(13). 1081 1082 if (Is_Volatile (E1) or else Has_Volatile_Components (E1)) 1083 and then not Is_Imported (E1) 1084 then 1085 Error_Msg_N 1086 ("?k?& is not modified, volatile has no effect!", E1); 1087 1088 -- Another special case, Exception_Occurrence, this catches 1089 -- the case of exception choice (and a bit more too, but not 1090 -- worth doing more investigation here). 1091 1092 elsif Is_RTE (E1T, RE_Exception_Occurrence) then 1093 null; 1094 1095 -- Here we give the warning if referenced and no pragma 1096 -- Unreferenced or Unmodified is present. 1097 1098 else 1099 -- Variable case 1100 1101 if Ekind (E1) = E_Variable then 1102 if Referenced_Check_Spec (E1) 1103 and then not Has_Pragma_Unreferenced_Check_Spec (E1) 1104 and then not Has_Pragma_Unmodified_Check_Spec (E1) 1105 then 1106 if not Warnings_Off_E1 then 1107 Error_Msg_N -- CODEFIX 1108 ("?k?& is not modified, " 1109 & "could be declared constant!", 1110 E1); 1111 end if; 1112 end if; 1113 end if; 1114 end if; 1115 1116 -- Other cases of a variable or parameter never set in source 1117 1118 elsif Never_Set_In_Source_Check_Spec (E1) 1119 1120 -- No warning if warning for this case turned off 1121 1122 and then Warn_On_No_Value_Assigned 1123 1124 -- No warning if address taken somewhere 1125 1126 and then not Address_Taken (E1) 1127 1128 -- No warning if explicit initial value 1129 1130 and then not Has_Initial_Value (E1) 1131 1132 -- No warning for generic package spec entities, since we 1133 -- might set them in a child unit or something like that 1134 1135 and then not Generic_Package_Spec_Entity (E1) 1136 1137 -- No warning if fully initialized type, except that for 1138 -- this purpose we do not consider access types to qualify 1139 -- as fully initialized types (relying on an access type 1140 -- variable being null when it is never set is a bit odd!) 1141 1142 -- Also we generate warning for an out parameter that is 1143 -- never referenced, since again it seems odd to rely on 1144 -- default initialization to set an out parameter value. 1145 1146 and then (Is_Access_Type (E1T) 1147 or else Ekind (E1) = E_Out_Parameter 1148 or else not Is_Fully_Initialized_Type (E1T)) 1149 then 1150 -- Do not output complaint about never being assigned a 1151 -- value if a pragma Unmodified applies to the variable 1152 -- we are examining, or if it is a parameter, if there is 1153 -- a pragma Unreferenced for the corresponding spec, or 1154 -- if the type is marked as having unreferenced objects. 1155 -- The last is a little peculiar, but better too few than 1156 -- too many warnings in this situation. 1157 1158 if Has_Pragma_Unreferenced_Objects (E1T) 1159 or else Has_Pragma_Unmodified_Check_Spec (E1) 1160 then 1161 null; 1162 1163 -- IN OUT parameter case where parameter is referenced. We 1164 -- separate this out, since this is the case where we delay 1165 -- output of the warning until more information is available 1166 -- (about use in an instantiation or address being taken). 1167 1168 elsif Ekind (E1) = E_In_Out_Parameter 1169 and then Referenced_Check_Spec (E1) 1170 then 1171 -- Suppress warning if private type, and the procedure 1172 -- has a separate declaration in a different unit. This 1173 -- is the case where the client of a package sees only 1174 -- the private type, and it may be quite reasonable 1175 -- for the logical view to be IN OUT, even if the 1176 -- implementation ends up using access types or some 1177 -- other method to achieve the local effect of a 1178 -- modification. On the other hand if the spec and body 1179 -- are in the same unit, we are in the package body and 1180 -- there we have less excuse for a junk IN OUT parameter. 1181 1182 if Has_Private_Declaration (E1T) 1183 and then Present (Spec_Entity (E1)) 1184 and then not In_Same_Source_Unit (E1, Spec_Entity (E1)) 1185 then 1186 null; 1187 1188 -- Suppress warning for any parameter of a dispatching 1189 -- operation, since it is quite reasonable to have an 1190 -- operation that is overridden, and for some subclasses 1191 -- needs the formal to be IN OUT and for others happens 1192 -- not to assign it. 1193 1194 elsif Is_Dispatching_Operation 1195 (Scope (Goto_Spec_Entity (E1))) 1196 then 1197 null; 1198 1199 -- Suppress warning if composite type contains any access 1200 -- component, since the logical effect of modifying a 1201 -- parameter may be achieved by modifying a referenced 1202 -- object. 1203 1204 elsif Is_Composite_Type (E1T) 1205 and then Has_Access_Values (E1T) 1206 then 1207 null; 1208 1209 -- Suppress warning on formals of an entry body. All 1210 -- references are attached to the formal in the entry 1211 -- declaration, which are marked Is_Entry_Formal. 1212 1213 elsif Ekind (Scope (E1)) = E_Entry 1214 and then not Is_Entry_Formal (E1) 1215 then 1216 null; 1217 1218 -- OK, looks like warning for an IN OUT parameter that 1219 -- could be IN makes sense, but we delay the output of 1220 -- the warning, pending possibly finding out later on 1221 -- that the associated subprogram is used as a generic 1222 -- actual, or its address/access is taken. In these two 1223 -- cases, we suppress the warning because the context may 1224 -- force use of IN OUT, even if in this particular case 1225 -- the formal is not modified. 1226 1227 else 1228 In_Out_Warnings.Append (E1); 1229 end if; 1230 1231 -- Other cases of formals 1232 1233 elsif Is_Formal (E1) then 1234 if not Is_Trivial_Subprogram (Scope (E1)) then 1235 if Referenced_Check_Spec (E1) then 1236 if not Has_Pragma_Unmodified_Check_Spec (E1) 1237 and then not Warnings_Off_E1 1238 then 1239 Output_Reference_Error 1240 ("?f?formal parameter& is read but " 1241 & "never assigned!"); 1242 end if; 1243 1244 elsif not Has_Pragma_Unreferenced_Check_Spec (E1) 1245 and then not Warnings_Off_E1 1246 then 1247 Output_Reference_Error 1248 ("?f?formal parameter& is not referenced!"); 1249 end if; 1250 end if; 1251 1252 -- Case of variable 1253 1254 else 1255 if Referenced (E1) then 1256 if not Has_Unmodified (E1) 1257 and then not Warnings_Off_E1 1258 then 1259 Output_Reference_Error 1260 ("?v?variable& is read but never assigned!"); 1261 end if; 1262 1263 elsif not Has_Unreferenced (E1) 1264 and then not Warnings_Off_E1 1265 then 1266 Output_Reference_Error -- CODEFIX 1267 ("?v?variable& is never read and never assigned!"); 1268 end if; 1269 1270 -- Deal with special case where this variable is hidden 1271 -- by a loop variable. 1272 1273 if Ekind (E1) = E_Variable 1274 and then Present (Hiding_Loop_Variable (E1)) 1275 and then not Warnings_Off_E1 1276 then 1277 Error_Msg_N 1278 ("?v?for loop implicitly declares loop variable!", 1279 Hiding_Loop_Variable (E1)); 1280 1281 Error_Msg_Sloc := Sloc (E1); 1282 Error_Msg_N 1283 ("\?v?declaration hides & declared#!", 1284 Hiding_Loop_Variable (E1)); 1285 end if; 1286 end if; 1287 1288 goto Continue; 1289 end if; 1290 1291 -- Check for unset reference 1292 1293 if Warn_On_No_Value_Assigned and then Present (UR) then 1294 1295 -- For other than access type, go back to original node to 1296 -- deal with case where original unset reference has been 1297 -- rewritten during expansion. 1298 1299 -- In some cases, the original node may be a type conversion 1300 -- or qualification, and in this case we want the object 1301 -- entity inside. 1302 1303 UR := Original_Node (UR); 1304 while Nkind (UR) = N_Type_Conversion 1305 or else Nkind (UR) = N_Qualified_Expression 1306 loop 1307 UR := Expression (UR); 1308 end loop; 1309 1310 -- Here we issue the warning, all checks completed 1311 1312 -- If we have a return statement, this was a case of an OUT 1313 -- parameter not being set at the time of the return. (Note: 1314 -- it can't be N_Extended_Return_Statement, because those 1315 -- are only for functions, and functions do not allow OUT 1316 -- parameters.) 1317 1318 if not Is_Trivial_Subprogram (Scope (E1)) then 1319 if Nkind (UR) = N_Simple_Return_Statement 1320 and then not Has_Pragma_Unmodified_Check_Spec (E1) 1321 then 1322 if not Warnings_Off_E1 then 1323 Error_Msg_NE 1324 ("?v?OUT parameter& not set before return", 1325 UR, E1); 1326 end if; 1327 1328 -- If the unset reference is a selected component 1329 -- prefix from source, mention the component as well. 1330 -- If the selected component comes from expansion, all 1331 -- we know is that the entity is not fully initialized 1332 -- at the point of the reference. Locate a random 1333 -- uninitialized component to get a better message. 1334 1335 elsif Nkind (Parent (UR)) = N_Selected_Component then 1336 Error_Msg_Node_2 := Selector_Name (Parent (UR)); 1337 1338 if not Comes_From_Source (Parent (UR)) then 1339 declare 1340 Comp : Entity_Id; 1341 1342 begin 1343 Comp := First_Entity (E1T); 1344 while Present (Comp) loop 1345 if Ekind (Comp) = E_Component 1346 and then Nkind (Parent (Comp)) = 1347 N_Component_Declaration 1348 and then No (Expression (Parent (Comp))) 1349 then 1350 Error_Msg_Node_2 := Comp; 1351 exit; 1352 end if; 1353 1354 Next_Entity (Comp); 1355 end loop; 1356 end; 1357 end if; 1358 1359 -- Issue proper warning. This is a case of referencing 1360 -- a variable before it has been explicitly assigned. 1361 -- For access types, UR was only set for dereferences, 1362 -- so the issue is that the value may be null. 1363 1364 if not Is_Trivial_Subprogram (Scope (E1)) then 1365 if not Warnings_Off_E1 then 1366 if Is_Access_Type (Etype (Parent (UR))) then 1367 Error_Msg_N ("?`&.&` may be null!", UR); 1368 else 1369 Error_Msg_N 1370 ("?`&.&` may be referenced before " 1371 & "it has a value!", UR); 1372 end if; 1373 end if; 1374 end if; 1375 1376 -- All other cases of unset reference active 1377 1378 elsif not Warnings_Off_E1 then 1379 Error_Msg_N 1380 ("?& may be referenced before it has a value!", 1381 UR); 1382 end if; 1383 end if; 1384 1385 goto Continue; 1386 end if; 1387 end if; 1388 1389 -- Then check for unreferenced entities. Note that we are only 1390 -- interested in entities whose Referenced flag is not set. 1391 1392 if not Referenced_Check_Spec (E1) 1393 1394 -- If Referenced_As_LHS is set, then that's still interesting 1395 -- (potential "assigned but never read" case), but not if we 1396 -- have pragma Unreferenced, which cancels this warning. 1397 1398 and then (not Referenced_As_LHS_Check_Spec (E1) 1399 or else not Has_Unreferenced (E1)) 1400 1401 -- Check that warnings on unreferenced entities are enabled 1402 1403 and then 1404 ((Check_Unreferenced and then not Is_Formal (E1)) 1405 1406 -- Case of warning on unreferenced formal 1407 1408 or else 1409 (Check_Unreferenced_Formals and then Is_Formal (E1)) 1410 1411 -- Case of warning on unread variables modified by an 1412 -- assignment, or an OUT parameter if it is the only one. 1413 1414 or else 1415 (Warn_On_Modified_Unread 1416 and then Referenced_As_LHS_Check_Spec (E1)) 1417 1418 -- Case of warning on any unread OUT parameter (note 1419 -- such indications are only set if the appropriate 1420 -- warning options were set, so no need to recheck here.) 1421 1422 or else 1423 Referenced_As_Out_Parameter_Check_Spec (E1)) 1424 1425 -- All other entities, including local packages that cannot be 1426 -- referenced from elsewhere, including those declared within a 1427 -- package body. 1428 1429 and then (Is_Object (E1) 1430 or else 1431 Is_Type (E1) 1432 or else 1433 Ekind (E1) = E_Label 1434 or else 1435 Ekind (E1) = E_Exception 1436 or else 1437 Ekind (E1) = E_Named_Integer 1438 or else 1439 Ekind (E1) = E_Named_Real 1440 or else 1441 Is_Overloadable (E1) 1442 1443 -- Package case, if the main unit is a package spec 1444 -- or generic package spec, then there may be a 1445 -- corresponding body that references this package 1446 -- in some other file. Otherwise we can be sure 1447 -- that there is no other reference. 1448 1449 or else 1450 (Ekind (E1) = E_Package 1451 and then 1452 not Is_Package_Or_Generic_Package 1453 (Cunit_Entity (Current_Sem_Unit)))) 1454 1455 -- Exclude instantiations, since there is no reason why every 1456 -- entity in an instantiation should be referenced. 1457 1458 and then Instantiation_Location (Sloc (E1)) = No_Location 1459 1460 -- Exclude formal parameters from bodies if the corresponding 1461 -- spec entity has been referenced in the case where there is 1462 -- a separate spec. 1463 1464 and then not (Is_Formal (E1) 1465 and then Ekind (Scope (E1)) = E_Subprogram_Body 1466 and then Present (Spec_Entity (E1)) 1467 and then Referenced (Spec_Entity (E1))) 1468 1469 -- Consider private type referenced if full view is referenced. 1470 -- If there is not full view, this is a generic type on which 1471 -- warnings are also useful. 1472 1473 and then 1474 not (Is_Private_Type (E1) 1475 and then Present (Full_View (E1)) 1476 and then Referenced (Full_View (E1))) 1477 1478 -- Don't worry about full view, only about private type 1479 1480 and then not Has_Private_Declaration (E1) 1481 1482 -- Eliminate dispatching operations from consideration, we 1483 -- cannot tell if these are referenced or not in any easy 1484 -- manner (note this also catches Adjust/Finalize/Initialize). 1485 1486 and then not Is_Dispatching_Operation (E1) 1487 1488 -- Check entity that can be publicly referenced (we do not give 1489 -- messages for such entities, since there could be other 1490 -- units, not involved in this compilation, that contain 1491 -- relevant references. 1492 1493 and then not Publicly_Referenceable (E1) 1494 1495 -- Class wide types are marked as source entities, but they are 1496 -- not really source entities, and are always created, so we do 1497 -- not care if they are not referenced. 1498 1499 and then Ekind (E1) /= E_Class_Wide_Type 1500 1501 -- Objects other than parameters of task types are allowed to 1502 -- be non-referenced, since they start up tasks! 1503 1504 and then ((Ekind (E1) /= E_Variable 1505 and then Ekind (E1) /= E_Constant 1506 and then Ekind (E1) /= E_Component) 1507 or else not Is_Task_Type (E1T)) 1508 1509 -- For subunits, only place warnings on the main unit itself, 1510 -- since parent units are not completely compiled. 1511 1512 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit 1513 or else Get_Source_Unit (E1) = Main_Unit) 1514 1515 -- No warning on a return object, because these are often 1516 -- created with a single expression and an implicit return. 1517 -- If the object is a variable there will be a warning 1518 -- indicating that it could be declared constant. 1519 1520 and then not 1521 (Ekind (E1) = E_Constant and then Is_Return_Object (E1)) 1522 then 1523 -- Suppress warnings in internal units if not in -gnatg mode 1524 -- (these would be junk warnings for an applications program, 1525 -- since they refer to problems in internal units). 1526 1527 if GNAT_Mode 1528 or else not Is_Internal_File_Name 1529 (Unit_File_Name (Get_Source_Unit (E1))) 1530 then 1531 -- We do not immediately flag the error. This is because we 1532 -- have not expanded generic bodies yet, and they may have 1533 -- the missing reference. So instead we park the entity on a 1534 -- list, for later processing. However for the case of an 1535 -- accept statement we want to output messages now, since 1536 -- we know we already have all information at hand, and we 1537 -- also want to have separate warnings for each accept 1538 -- statement for the same entry. 1539 1540 if Present (Anod) then 1541 pragma Assert (Is_Formal (E1)); 1542 1543 -- The unreferenced entity is E1, but post the warning 1544 -- on the body entity for this accept statement. 1545 1546 if not Warnings_Off_E1 then 1547 Warn_On_Unreferenced_Entity 1548 (E1, Body_Formal (E1, Accept_Statement => Anod)); 1549 end if; 1550 1551 elsif not Warnings_Off_E1 then 1552 Unreferenced_Entities.Append (E1); 1553 end if; 1554 end if; 1555 1556 -- Generic units are referenced in the generic body, but if they 1557 -- are not public and never instantiated we want to force a 1558 -- warning on them. We treat them as redundant constructs to 1559 -- minimize noise. 1560 1561 elsif Is_Generic_Subprogram (E1) 1562 and then not Is_Instantiated (E1) 1563 and then not Publicly_Referenceable (E1) 1564 and then Instantiation_Depth (Sloc (E1)) = 0 1565 and then Warn_On_Redundant_Constructs 1566 then 1567 if not Warnings_Off_E1 then 1568 Unreferenced_Entities.Append (E1); 1569 1570 -- Force warning on entity 1571 1572 Set_Referenced (E1, False); 1573 end if; 1574 end if; 1575 end if; 1576 1577 -- Recurse into nested package or block. Do not recurse into a formal 1578 -- package, because the corresponding body is not analyzed. 1579 1580 <<Continue>> 1581 if (Is_Package_Or_Generic_Package (E1) 1582 and then Nkind (Parent (E1)) = N_Package_Specification 1583 and then 1584 Nkind (Original_Node (Unit_Declaration_Node (E1))) 1585 /= N_Formal_Package_Declaration) 1586 1587 or else Ekind (E1) = E_Block 1588 then 1589 Check_References (E1); 1590 end if; 1591 1592 Next_Entity (E1); 1593 end loop; 1594 end Check_References; 1595 1596 --------------------------- 1597 -- Check_Unset_Reference -- 1598 --------------------------- 1599 1600 procedure Check_Unset_Reference (N : Node_Id) is 1601 Typ : constant Entity_Id := Etype (N); 1602 1603 function Is_OK_Fully_Initialized return Boolean; 1604 -- This function returns true if the given node N is fully initialized 1605 -- so that the reference is safe as far as this routine is concerned. 1606 -- Safe generally means that the type of N is a fully initialized type. 1607 -- The one special case is that for access types, which are always fully 1608 -- initialized, we don't consider a dereference OK since it will surely 1609 -- be dereferencing a null value, which won't do. 1610 1611 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean; 1612 -- Used to test indexed or selected component or slice to see if the 1613 -- evaluation of the prefix depends on a dereference, and if so, returns 1614 -- True, in which case we always check the prefix, even if we know that 1615 -- the referenced component is initialized. Pref is the prefix to test. 1616 1617 ----------------------------- 1618 -- Is_OK_Fully_Initialized -- 1619 ----------------------------- 1620 1621 function Is_OK_Fully_Initialized return Boolean is 1622 begin 1623 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then 1624 return False; 1625 else 1626 return Is_Fully_Initialized_Type (Typ); 1627 end if; 1628 end Is_OK_Fully_Initialized; 1629 1630 ---------------------------- 1631 -- Prefix_Has_Dereference -- 1632 ---------------------------- 1633 1634 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is 1635 begin 1636 -- If prefix is of an access type, it certainly needs a dereference 1637 1638 if Is_Access_Type (Etype (Pref)) then 1639 return True; 1640 1641 -- If prefix is explicit dereference, that's a dereference for sure 1642 1643 elsif Nkind (Pref) = N_Explicit_Dereference then 1644 return True; 1645 1646 -- If prefix is itself a component reference or slice check prefix 1647 1648 elsif Nkind (Pref) = N_Slice 1649 or else Nkind (Pref) = N_Indexed_Component 1650 or else Nkind (Pref) = N_Selected_Component 1651 then 1652 return Prefix_Has_Dereference (Prefix (Pref)); 1653 1654 -- All other cases do not involve a dereference 1655 1656 else 1657 return False; 1658 end if; 1659 end Prefix_Has_Dereference; 1660 1661 -- Start of processing for Check_Unset_Reference 1662 1663 begin 1664 -- Nothing to do if warnings suppressed 1665 1666 if Warning_Mode = Suppress then 1667 return; 1668 end if; 1669 1670 -- Ignore reference unless it comes from source. Almost always if we 1671 -- have a reference from generated code, it is bogus (e.g. calls to init 1672 -- procs to set default discriminant values). 1673 1674 if not Comes_From_Source (N) then 1675 return; 1676 end if; 1677 1678 -- Otherwise see what kind of node we have. If the entity already has an 1679 -- unset reference, it is not necessarily the earliest in the text, 1680 -- because resolution of the prefix of selected components is completed 1681 -- before the resolution of the selected component itself. As a result, 1682 -- given (R /= null and then R.X > 0), the occurrences of R are examined 1683 -- in right-to-left order. If there is already an unset reference, we 1684 -- check whether N is earlier before proceeding. 1685 1686 case Nkind (N) is 1687 1688 -- For identifier or expanded name, examine the entity involved 1689 1690 when N_Identifier | N_Expanded_Name => 1691 declare 1692 E : constant Entity_Id := Entity (N); 1693 1694 begin 1695 if (Ekind (E) = E_Variable 1696 or else 1697 Ekind (E) = E_Out_Parameter) 1698 and then Never_Set_In_Source_Check_Spec (E) 1699 and then not Has_Initial_Value (E) 1700 and then (No (Unset_Reference (E)) 1701 or else 1702 Earlier_In_Extended_Unit 1703 (Sloc (N), Sloc (Unset_Reference (E)))) 1704 and then not Has_Pragma_Unmodified_Check_Spec (E) 1705 and then not Warnings_Off_Check_Spec (E) 1706 then 1707 -- We may have an unset reference. The first test is whether 1708 -- this is an access to a discriminant of a record or a 1709 -- component with default initialization. Both of these 1710 -- cases can be ignored, since the actual object that is 1711 -- referenced is definitely initialized. Note that this 1712 -- covers the case of reading discriminants of an OUT 1713 -- parameter, which is OK even in Ada 83. 1714 1715 -- Note that we are only interested in a direct reference to 1716 -- a record component here. If the reference is through an 1717 -- access type, then the access object is being referenced, 1718 -- not the record, and still deserves an unset reference. 1719 1720 if Nkind (Parent (N)) = N_Selected_Component 1721 and not Is_Access_Type (Typ) 1722 then 1723 declare 1724 ES : constant Entity_Id := 1725 Entity (Selector_Name (Parent (N))); 1726 begin 1727 if Ekind (ES) = E_Discriminant 1728 or else 1729 (Present (Declaration_Node (ES)) 1730 and then 1731 Present (Expression (Declaration_Node (ES)))) 1732 then 1733 return; 1734 end if; 1735 end; 1736 end if; 1737 1738 -- Exclude fully initialized types 1739 1740 if Is_OK_Fully_Initialized then 1741 return; 1742 end if; 1743 1744 -- Here we have a potential unset reference. But before we 1745 -- get worried about it, we have to make sure that the 1746 -- entity declaration is in the same procedure as the 1747 -- reference, since if they are in separate procedures, then 1748 -- we have no idea about sequential execution. 1749 1750 -- The tests in the loop below catch all such cases, but do 1751 -- allow the reference to appear in a loop, block, or 1752 -- package spec that is nested within the declaring scope. 1753 -- As always, it is possible to construct cases where the 1754 -- warning is wrong, that is why it is a warning! 1755 1756 Potential_Unset_Reference : declare 1757 SR : Entity_Id; 1758 SE : constant Entity_Id := Scope (E); 1759 1760 function Within_Postcondition return Boolean; 1761 -- Returns True iff N is within a Postcondition or 1762 -- Ensures component in a Contract_Case or Test_Case. 1763 1764 -------------------------- 1765 -- Within_Postcondition -- 1766 -------------------------- 1767 1768 function Within_Postcondition return Boolean is 1769 Nod, P : Node_Id; 1770 1771 begin 1772 Nod := Parent (N); 1773 while Present (Nod) loop 1774 if Nkind (Nod) = N_Pragma 1775 and then Pragma_Name (Nod) = Name_Postcondition 1776 then 1777 return True; 1778 1779 elsif Present (Parent (Nod)) then 1780 P := Parent (Nod); 1781 1782 if Nkind (P) = N_Pragma 1783 and then 1784 (Pragma_Name (P) = Name_Contract_Case 1785 or else 1786 Pragma_Name (P) = Name_Test_Case) 1787 and then 1788 Nod = Get_Ensures_From_CTC_Pragma (P) 1789 then 1790 return True; 1791 end if; 1792 end if; 1793 1794 Nod := Parent (Nod); 1795 end loop; 1796 1797 return False; 1798 end Within_Postcondition; 1799 1800 -- Start of processing for Potential_Unset_Reference 1801 1802 begin 1803 SR := Current_Scope; 1804 while SR /= SE loop 1805 if SR = Standard_Standard 1806 or else Is_Subprogram (SR) 1807 or else Is_Concurrent_Body (SR) 1808 or else Is_Concurrent_Type (SR) 1809 then 1810 return; 1811 end if; 1812 1813 SR := Scope (SR); 1814 end loop; 1815 1816 -- Case of reference has an access type. This is a 1817 -- special case since access types are always set to null 1818 -- so cannot be truly uninitialized, but we still want to 1819 -- warn about cases of obvious null dereference. 1820 1821 if Is_Access_Type (Typ) then 1822 Access_Type_Case : declare 1823 P : Node_Id; 1824 1825 function Process 1826 (N : Node_Id) return Traverse_Result; 1827 -- Process function for instantiation of Traverse 1828 -- below. Checks if N contains reference to E other 1829 -- than a dereference. 1830 1831 function Ref_In (Nod : Node_Id) return Boolean; 1832 -- Determines whether Nod contains a reference to 1833 -- the entity E that is not a dereference. 1834 1835 ------------- 1836 -- Process -- 1837 ------------- 1838 1839 function Process 1840 (N : Node_Id) return Traverse_Result 1841 is 1842 begin 1843 if Is_Entity_Name (N) 1844 and then Entity (N) = E 1845 and then not Is_Dereferenced (N) 1846 then 1847 return Abandon; 1848 else 1849 return OK; 1850 end if; 1851 end Process; 1852 1853 ------------ 1854 -- Ref_In -- 1855 ------------ 1856 1857 function Ref_In (Nod : Node_Id) return Boolean is 1858 function Traverse is new Traverse_Func (Process); 1859 begin 1860 return Traverse (Nod) = Abandon; 1861 end Ref_In; 1862 1863 -- Start of processing for Access_Type_Case 1864 1865 begin 1866 -- Don't bother if we are inside an instance, since 1867 -- the compilation of the generic template is where 1868 -- the warning should be issued. 1869 1870 if In_Instance then 1871 return; 1872 end if; 1873 1874 -- Don't bother if this is not the main unit. If we 1875 -- try to give this warning for with'ed units, we 1876 -- get some false positives, since we do not record 1877 -- references in other units. 1878 1879 if not In_Extended_Main_Source_Unit (E) 1880 or else 1881 not In_Extended_Main_Source_Unit (N) 1882 then 1883 return; 1884 end if; 1885 1886 -- We are only interested in dereferences 1887 1888 if not Is_Dereferenced (N) then 1889 return; 1890 end if; 1891 1892 -- One more check, don't bother with references 1893 -- that are inside conditional statements or WHILE 1894 -- loops if the condition references the entity in 1895 -- question. This avoids most false positives. 1896 1897 P := Parent (N); 1898 loop 1899 P := Parent (P); 1900 exit when No (P); 1901 1902 if (Nkind (P) = N_If_Statement 1903 or else 1904 Nkind (P) = N_Elsif_Part) 1905 and then Ref_In (Condition (P)) 1906 then 1907 return; 1908 1909 elsif Nkind (P) = N_Loop_Statement 1910 and then Present (Iteration_Scheme (P)) 1911 and then 1912 Ref_In (Condition (Iteration_Scheme (P))) 1913 then 1914 return; 1915 end if; 1916 end loop; 1917 end Access_Type_Case; 1918 end if; 1919 1920 -- One more check, don't bother if we are within a 1921 -- postcondition, since the expression occurs in a 1922 -- place unrelated to the actual test. 1923 1924 if not Within_Postcondition then 1925 1926 -- Here we definitely have a case for giving a warning 1927 -- for a reference to an unset value. But we don't 1928 -- give the warning now. Instead set Unset_Reference 1929 -- in the identifier involved. The reason for this is 1930 -- that if we find the variable is never ever assigned 1931 -- a value then that warning is more important and 1932 -- there is no point in giving the reference warning. 1933 1934 -- If this is an identifier, set the field directly 1935 1936 if Nkind (N) = N_Identifier then 1937 Set_Unset_Reference (E, N); 1938 1939 -- Otherwise it is an expanded name, so set the field 1940 -- of the actual identifier for the reference. 1941 1942 else 1943 Set_Unset_Reference (E, Selector_Name (N)); 1944 end if; 1945 end if; 1946 end Potential_Unset_Reference; 1947 end if; 1948 end; 1949 1950 -- Indexed component or slice 1951 1952 when N_Indexed_Component | N_Slice => 1953 1954 -- If prefix does not involve dereferencing an access type, then 1955 -- we know we are OK if the component type is fully initialized, 1956 -- since the component will have been set as part of the default 1957 -- initialization. 1958 1959 if not Prefix_Has_Dereference (Prefix (N)) 1960 and then Is_OK_Fully_Initialized 1961 then 1962 return; 1963 1964 -- Look at prefix in access type case, or if the component is not 1965 -- fully initialized. 1966 1967 else 1968 Check_Unset_Reference (Prefix (N)); 1969 end if; 1970 1971 -- Record component 1972 1973 when N_Selected_Component => 1974 declare 1975 Pref : constant Node_Id := Prefix (N); 1976 Ent : constant Entity_Id := Entity (Selector_Name (N)); 1977 1978 begin 1979 -- If prefix involves dereferencing an access type, always 1980 -- check the prefix, since the issue then is whether this 1981 -- access value is null. 1982 1983 if Prefix_Has_Dereference (Pref) then 1984 null; 1985 1986 -- Always go to prefix if no selector entity is set. Can this 1987 -- happen in the normal case? Not clear, but it definitely can 1988 -- happen in error cases. 1989 1990 elsif No (Ent) then 1991 null; 1992 1993 -- For a record component, check some cases where we have 1994 -- reasonable cause to consider that the component is known to 1995 -- be or probably is initialized. In this case, we don't care 1996 -- if the prefix itself was explicitly initialized. 1997 1998 -- Discriminants are always considered initialized 1999 2000 elsif Ekind (Ent) = E_Discriminant then 2001 return; 2002 2003 -- An explicitly initialized component is certainly initialized 2004 2005 elsif Nkind (Parent (Ent)) = N_Component_Declaration 2006 and then Present (Expression (Parent (Ent))) 2007 then 2008 return; 2009 2010 -- A fully initialized component is initialized 2011 2012 elsif Is_OK_Fully_Initialized then 2013 return; 2014 end if; 2015 2016 -- If none of those cases apply, check the record type prefix 2017 2018 Check_Unset_Reference (Pref); 2019 end; 2020 2021 -- For type conversions or qualifications examine the expression 2022 2023 when N_Type_Conversion | N_Qualified_Expression => 2024 Check_Unset_Reference (Expression (N)); 2025 2026 -- For explicit dereference, always check prefix, which will generate 2027 -- an unset reference (since this is a case of dereferencing null). 2028 2029 when N_Explicit_Dereference => 2030 Check_Unset_Reference (Prefix (N)); 2031 2032 -- All other cases are not cases of an unset reference 2033 2034 when others => 2035 null; 2036 2037 end case; 2038 end Check_Unset_Reference; 2039 2040 ------------------------ 2041 -- Check_Unused_Withs -- 2042 ------------------------ 2043 2044 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is 2045 Cnode : Node_Id; 2046 Item : Node_Id; 2047 Lunit : Node_Id; 2048 Ent : Entity_Id; 2049 2050 Munite : constant Entity_Id := Cunit_Entity (Main_Unit); 2051 -- This is needed for checking the special renaming case 2052 2053 procedure Check_One_Unit (Unit : Unit_Number_Type); 2054 -- Subsidiary procedure, performs checks for specified unit 2055 2056 -------------------- 2057 -- Check_One_Unit -- 2058 -------------------- 2059 2060 procedure Check_One_Unit (Unit : Unit_Number_Type) is 2061 Is_Visible_Renaming : Boolean := False; 2062 Pack : Entity_Id; 2063 2064 procedure Check_Inner_Package (Pack : Entity_Id); 2065 -- Pack is a package local to a unit in a with_clause. Both the unit 2066 -- and Pack are referenced. If none of the entities in Pack are 2067 -- referenced, then the only occurrence of Pack is in a USE clause 2068 -- or a pragma, and a warning is worthwhile as well. 2069 2070 function Check_System_Aux return Boolean; 2071 -- Before giving a warning on a with_clause for System, check whether 2072 -- a system extension is present. 2073 2074 function Find_Package_Renaming 2075 (P : Entity_Id; 2076 L : Entity_Id) return Entity_Id; 2077 -- The only reference to a context unit may be in a renaming 2078 -- declaration. If this renaming declares a visible entity, do not 2079 -- warn that the context clause could be moved to the body, because 2080 -- the renaming may be intended to re-export the unit. 2081 2082 function Has_Visible_Entities (P : Entity_Id) return Boolean; 2083 -- This function determines if a package has any visible entities. 2084 -- True is returned if there is at least one declared visible entity, 2085 -- otherwise False is returned (e.g. case of only pragmas present). 2086 2087 ------------------------- 2088 -- Check_Inner_Package -- 2089 ------------------------- 2090 2091 procedure Check_Inner_Package (Pack : Entity_Id) is 2092 E : Entity_Id; 2093 Un : constant Node_Id := Sinfo.Unit (Cnode); 2094 2095 function Check_Use_Clause (N : Node_Id) return Traverse_Result; 2096 -- If N is a use_clause for Pack, emit warning 2097 2098 procedure Check_Use_Clauses is new 2099 Traverse_Proc (Check_Use_Clause); 2100 2101 ---------------------- 2102 -- Check_Use_Clause -- 2103 ---------------------- 2104 2105 function Check_Use_Clause (N : Node_Id) return Traverse_Result is 2106 Nam : Node_Id; 2107 2108 begin 2109 if Nkind (N) = N_Use_Package_Clause then 2110 Nam := First (Names (N)); 2111 while Present (Nam) loop 2112 if Entity (Nam) = Pack then 2113 Error_Msg_Qual_Level := 1; 2114 Error_Msg_NE -- CODEFIX 2115 ("?u?no entities of package& are referenced!", 2116 Nam, Pack); 2117 Error_Msg_Qual_Level := 0; 2118 end if; 2119 2120 Next (Nam); 2121 end loop; 2122 end if; 2123 2124 return OK; 2125 end Check_Use_Clause; 2126 2127 -- Start of processing for Check_Inner_Package 2128 2129 begin 2130 E := First_Entity (Pack); 2131 while Present (E) loop 2132 if Referenced_Check_Spec (E) then 2133 return; 2134 end if; 2135 2136 Next_Entity (E); 2137 end loop; 2138 2139 -- No entities of the package are referenced. Check whether the 2140 -- reference to the package itself is a use clause, and if so 2141 -- place a warning on it. 2142 2143 Check_Use_Clauses (Un); 2144 end Check_Inner_Package; 2145 2146 ---------------------- 2147 -- Check_System_Aux -- 2148 ---------------------- 2149 2150 function Check_System_Aux return Boolean is 2151 Ent : Entity_Id; 2152 2153 begin 2154 if Chars (Lunit) = Name_System 2155 and then Scope (Lunit) = Standard_Standard 2156 and then Present_System_Aux 2157 then 2158 Ent := First_Entity (System_Aux_Id); 2159 while Present (Ent) loop 2160 if Referenced_Check_Spec (Ent) then 2161 return True; 2162 end if; 2163 2164 Next_Entity (Ent); 2165 end loop; 2166 end if; 2167 2168 return False; 2169 end Check_System_Aux; 2170 2171 --------------------------- 2172 -- Find_Package_Renaming -- 2173 --------------------------- 2174 2175 function Find_Package_Renaming 2176 (P : Entity_Id; 2177 L : Entity_Id) return Entity_Id 2178 is 2179 E1 : Entity_Id; 2180 R : Entity_Id; 2181 2182 begin 2183 Is_Visible_Renaming := False; 2184 2185 E1 := First_Entity (P); 2186 while Present (E1) loop 2187 if Ekind (E1) = E_Package 2188 and then Renamed_Object (E1) = L 2189 then 2190 Is_Visible_Renaming := not Is_Hidden (E1); 2191 return E1; 2192 2193 elsif Ekind (E1) = E_Package 2194 and then No (Renamed_Object (E1)) 2195 and then not Is_Generic_Instance (E1) 2196 then 2197 R := Find_Package_Renaming (E1, L); 2198 2199 if Present (R) then 2200 Is_Visible_Renaming := not Is_Hidden (R); 2201 return R; 2202 end if; 2203 end if; 2204 2205 Next_Entity (E1); 2206 end loop; 2207 2208 return Empty; 2209 end Find_Package_Renaming; 2210 2211 -------------------------- 2212 -- Has_Visible_Entities -- 2213 -------------------------- 2214 2215 function Has_Visible_Entities (P : Entity_Id) return Boolean is 2216 E : Entity_Id; 2217 2218 begin 2219 -- If unit in context is not a package, it is a subprogram that 2220 -- is not called or a generic unit that is not instantiated 2221 -- in the current unit, and warning is appropriate. 2222 2223 if Ekind (P) /= E_Package then 2224 return True; 2225 end if; 2226 2227 -- If unit comes from a limited_with clause, look for declaration 2228 -- of shadow entities. 2229 2230 if Present (Limited_View (P)) then 2231 E := First_Entity (Limited_View (P)); 2232 else 2233 E := First_Entity (P); 2234 end if; 2235 2236 while Present (E) 2237 and then E /= First_Private_Entity (P) 2238 loop 2239 if Comes_From_Source (E) 2240 or else Present (Limited_View (P)) 2241 then 2242 return True; 2243 end if; 2244 2245 Next_Entity (E); 2246 end loop; 2247 2248 return False; 2249 end Has_Visible_Entities; 2250 2251 -- Start of processing for Check_One_Unit 2252 2253 begin 2254 Cnode := Cunit (Unit); 2255 2256 -- Only do check in units that are part of the extended main unit. 2257 -- This is actually a necessary restriction, because in the case of 2258 -- subprogram acting as its own specification, there can be with's in 2259 -- subunits that we will not see. 2260 2261 if not In_Extended_Main_Source_Unit (Cnode) then 2262 return; 2263 2264 -- In configurable run time mode, we remove the bodies of non-inlined 2265 -- subprograms, which may lead to spurious warnings, which are 2266 -- clearly undesirable. 2267 2268 elsif Configurable_Run_Time_Mode 2269 and then Is_Predefined_File_Name (Unit_File_Name (Unit)) 2270 then 2271 return; 2272 end if; 2273 2274 -- Loop through context items in this unit 2275 2276 Item := First (Context_Items (Cnode)); 2277 while Present (Item) loop 2278 if Nkind (Item) = N_With_Clause 2279 and then not Implicit_With (Item) 2280 and then In_Extended_Main_Source_Unit (Item) 2281 then 2282 Lunit := Entity (Name (Item)); 2283 2284 -- Check if this unit is referenced (skip the check if this 2285 -- is explicitly marked by a pragma Unreferenced). 2286 2287 if not Referenced (Lunit) 2288 and then not Has_Unreferenced (Lunit) 2289 then 2290 -- Suppress warnings in internal units if not in -gnatg mode 2291 -- (these would be junk warnings for an application program, 2292 -- since they refer to problems in internal units). 2293 2294 if GNAT_Mode 2295 or else not Is_Internal_File_Name (Unit_File_Name (Unit)) 2296 then 2297 -- Here we definitely have a non-referenced unit. If it 2298 -- is the special call for a spec unit, then just set the 2299 -- flag to be read later. 2300 2301 if Unit = Spec_Unit then 2302 Set_Unreferenced_In_Spec (Item); 2303 2304 -- Otherwise simple unreferenced message, but skip this 2305 -- if no visible entities, because that is most likely a 2306 -- case where warning would be false positive (e.g. a 2307 -- package with only a linker options pragma and nothing 2308 -- else or a pragma elaborate with a body library task). 2309 2310 elsif Has_Visible_Entities (Entity (Name (Item))) then 2311 Error_Msg_N -- CODEFIX 2312 ("?u?unit& is not referenced!", Name (Item)); 2313 end if; 2314 end if; 2315 2316 -- If main unit is a renaming of this unit, then we consider 2317 -- the with to be OK (obviously it is needed in this case!) 2318 -- This may be transitive: the unit in the with_clause may 2319 -- itself be a renaming, in which case both it and the main 2320 -- unit rename the same ultimate package. 2321 2322 elsif Present (Renamed_Entity (Munite)) 2323 and then 2324 (Renamed_Entity (Munite) = Lunit 2325 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit)) 2326 then 2327 null; 2328 2329 -- If this unit is referenced, and it is a package, we do 2330 -- another test, to see if any of the entities in the package 2331 -- are referenced. If none of the entities are referenced, we 2332 -- still post a warning. This occurs if the only use of the 2333 -- package is in a use clause, or in a package renaming 2334 -- declaration. This check is skipped for packages that are 2335 -- renamed in a spec, since the entities in such a package are 2336 -- visible to clients via the renaming. 2337 2338 elsif Ekind (Lunit) = E_Package 2339 and then not Renamed_In_Spec (Lunit) 2340 then 2341 -- If Is_Instantiated is set, it means that the package is 2342 -- implicitly instantiated (this is the case of parent 2343 -- instance or an actual for a generic package formal), and 2344 -- this counts as a reference. 2345 2346 if Is_Instantiated (Lunit) then 2347 null; 2348 2349 -- If no entities in package, and there is a pragma 2350 -- Elaborate_Body present, then assume that this with is 2351 -- done for purposes of this elaboration. 2352 2353 elsif No (First_Entity (Lunit)) 2354 and then Has_Pragma_Elaborate_Body (Lunit) 2355 then 2356 null; 2357 2358 -- Otherwise see if any entities have been referenced 2359 2360 else 2361 if Limited_Present (Item) then 2362 Ent := First_Entity (Limited_View (Lunit)); 2363 else 2364 Ent := First_Entity (Lunit); 2365 end if; 2366 2367 loop 2368 -- No more entities, and we did not find one that was 2369 -- referenced. Means we have a definite case of a with 2370 -- none of whose entities was referenced. 2371 2372 if No (Ent) then 2373 2374 -- If in spec, just set the flag 2375 2376 if Unit = Spec_Unit then 2377 Set_No_Entities_Ref_In_Spec (Item); 2378 2379 elsif Check_System_Aux then 2380 null; 2381 2382 -- Else give the warning 2383 2384 else 2385 if not 2386 Has_Unreferenced (Entity (Name (Item))) 2387 then 2388 Error_Msg_N -- CODEFIX 2389 ("?u?no entities of & are referenced!", 2390 Name (Item)); 2391 end if; 2392 2393 -- Look for renamings of this package, and flag 2394 -- them as well. If the original package has 2395 -- warnings off, we suppress the warning on the 2396 -- renaming as well. 2397 2398 Pack := Find_Package_Renaming (Munite, Lunit); 2399 2400 if Present (Pack) 2401 and then not Has_Warnings_Off (Lunit) 2402 and then not Has_Unreferenced (Pack) 2403 then 2404 Error_Msg_NE -- CODEFIX 2405 ("?u?no entities of & are referenced!", 2406 Unit_Declaration_Node (Pack), 2407 Pack); 2408 end if; 2409 end if; 2410 2411 exit; 2412 2413 -- Case of entity being referenced. The reference may 2414 -- come from a limited_with_clause, in which case the 2415 -- limited view of the entity carries the flag. 2416 2417 elsif Referenced_Check_Spec (Ent) 2418 or else Referenced_As_LHS_Check_Spec (Ent) 2419 or else Referenced_As_Out_Parameter_Check_Spec (Ent) 2420 or else 2421 (From_With_Type (Ent) 2422 and then Is_Incomplete_Type (Ent) 2423 and then Present (Non_Limited_View (Ent)) 2424 and then Referenced (Non_Limited_View (Ent))) 2425 then 2426 -- This means that the with is indeed fine, in that 2427 -- it is definitely needed somewhere, and we can 2428 -- quit worrying about this one... 2429 2430 -- Except for one little detail: if either of the 2431 -- flags was set during spec processing, this is 2432 -- where we complain that the with could be moved 2433 -- from the spec. If the spec contains a visible 2434 -- renaming of the package, inhibit warning to move 2435 -- with_clause to body. 2436 2437 if Ekind (Munite) = E_Package_Body then 2438 Pack := 2439 Find_Package_Renaming 2440 (Spec_Entity (Munite), Lunit); 2441 else 2442 Pack := Empty; 2443 end if; 2444 2445 -- If a renaming is present in the spec do not warn 2446 -- because the body or child unit may depend on it. 2447 2448 if Present (Pack) 2449 and then Renamed_Entity (Pack) = Lunit 2450 then 2451 exit; 2452 2453 elsif Unreferenced_In_Spec (Item) then 2454 Error_Msg_N -- CODEFIX 2455 ("?u?unit& is not referenced in spec!", 2456 Name (Item)); 2457 2458 elsif No_Entities_Ref_In_Spec (Item) then 2459 Error_Msg_N -- CODEFIX 2460 ("?u?no entities of & are referenced in spec!", 2461 Name (Item)); 2462 2463 else 2464 if Ekind (Ent) = E_Package then 2465 Check_Inner_Package (Ent); 2466 end if; 2467 2468 exit; 2469 end if; 2470 2471 if not Is_Visible_Renaming then 2472 Error_Msg_N -- CODEFIX 2473 ("\?u?with clause might be moved to body!", 2474 Name (Item)); 2475 end if; 2476 2477 exit; 2478 2479 -- Move to next entity to continue search 2480 2481 else 2482 Next_Entity (Ent); 2483 end if; 2484 end loop; 2485 end if; 2486 2487 -- For a generic package, the only interesting kind of 2488 -- reference is an instantiation, since entities cannot be 2489 -- referenced directly. 2490 2491 elsif Is_Generic_Unit (Lunit) then 2492 2493 -- Unit was never instantiated, set flag for case of spec 2494 -- call, or give warning for normal call. 2495 2496 if not Is_Instantiated (Lunit) then 2497 if Unit = Spec_Unit then 2498 Set_Unreferenced_In_Spec (Item); 2499 else 2500 Error_Msg_N -- CODEFIX 2501 ("?u?unit& is never instantiated!", Name (Item)); 2502 end if; 2503 2504 -- If unit was indeed instantiated, make sure that flag is 2505 -- not set showing it was uninstantiated in the spec, and if 2506 -- so, give warning. 2507 2508 elsif Unreferenced_In_Spec (Item) then 2509 Error_Msg_N 2510 ("?u?unit& is not instantiated in spec!", Name (Item)); 2511 Error_Msg_N -- CODEFIX 2512 ("\?u?with clause can be moved to body!", Name (Item)); 2513 end if; 2514 end if; 2515 end if; 2516 2517 Next (Item); 2518 end loop; 2519 end Check_One_Unit; 2520 2521 -- Start of processing for Check_Unused_Withs 2522 2523 begin 2524 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then 2525 return; 2526 end if; 2527 2528 -- Flag any unused with clauses, but skip this step if we are compiling 2529 -- a subunit on its own, since we do not have enough information to 2530 -- determine whether with's are used. We will get the relevant warnings 2531 -- when we compile the parent. This is the normal style of GNAT 2532 -- compilation in any case. 2533 2534 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then 2535 return; 2536 end if; 2537 2538 -- Process specified units 2539 2540 if Spec_Unit = No_Unit then 2541 2542 -- For main call, check all units 2543 2544 for Unit in Main_Unit .. Last_Unit loop 2545 Check_One_Unit (Unit); 2546 end loop; 2547 2548 else 2549 -- For call for spec, check only the spec 2550 2551 Check_One_Unit (Spec_Unit); 2552 end if; 2553 end Check_Unused_Withs; 2554 2555 --------------------------------- 2556 -- Generic_Package_Spec_Entity -- 2557 --------------------------------- 2558 2559 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is 2560 S : Entity_Id; 2561 2562 begin 2563 if Is_Package_Body_Entity (E) then 2564 return False; 2565 2566 else 2567 S := Scope (E); 2568 loop 2569 if S = Standard_Standard then 2570 return False; 2571 2572 elsif Ekind (S) = E_Generic_Package then 2573 return True; 2574 2575 elsif Ekind (S) = E_Package then 2576 S := Scope (S); 2577 2578 else 2579 return False; 2580 end if; 2581 end loop; 2582 end if; 2583 end Generic_Package_Spec_Entity; 2584 2585 ---------------------- 2586 -- Goto_Spec_Entity -- 2587 ---------------------- 2588 2589 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is 2590 begin 2591 if Is_Formal (E) 2592 and then Present (Spec_Entity (E)) 2593 then 2594 return Spec_Entity (E); 2595 else 2596 return E; 2597 end if; 2598 end Goto_Spec_Entity; 2599 2600 -------------------------------------- 2601 -- Has_Pragma_Unmodified_Check_Spec -- 2602 -------------------------------------- 2603 2604 function Has_Pragma_Unmodified_Check_Spec 2605 (E : Entity_Id) return Boolean 2606 is 2607 begin 2608 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2609 2610 -- Note: use of OR instead of OR ELSE here is deliberate, we want 2611 -- to mess with Unmodified flags on both body and spec entities. 2612 2613 return Has_Unmodified (E) 2614 or 2615 Has_Unmodified (Spec_Entity (E)); 2616 2617 else 2618 return Has_Unmodified (E); 2619 end if; 2620 end Has_Pragma_Unmodified_Check_Spec; 2621 2622 ---------------------------------------- 2623 -- Has_Pragma_Unreferenced_Check_Spec -- 2624 ---------------------------------------- 2625 2626 function Has_Pragma_Unreferenced_Check_Spec 2627 (E : Entity_Id) return Boolean 2628 is 2629 begin 2630 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2631 2632 -- Note: use of OR here instead of OR ELSE is deliberate, we want 2633 -- to mess with flags on both entities. 2634 2635 return Has_Unreferenced (E) 2636 or 2637 Has_Unreferenced (Spec_Entity (E)); 2638 2639 else 2640 return Has_Unreferenced (E); 2641 end if; 2642 end Has_Pragma_Unreferenced_Check_Spec; 2643 2644 ---------------- 2645 -- Initialize -- 2646 ---------------- 2647 2648 procedure Initialize is 2649 begin 2650 Warnings_Off_Pragmas.Init; 2651 Unreferenced_Entities.Init; 2652 In_Out_Warnings.Init; 2653 end Initialize; 2654 2655 ------------------------------------ 2656 -- Never_Set_In_Source_Check_Spec -- 2657 ------------------------------------ 2658 2659 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is 2660 begin 2661 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2662 return Never_Set_In_Source (E) 2663 and then 2664 Never_Set_In_Source (Spec_Entity (E)); 2665 else 2666 return Never_Set_In_Source (E); 2667 end if; 2668 end Never_Set_In_Source_Check_Spec; 2669 2670 ------------------------------------- 2671 -- Operand_Has_Warnings_Suppressed -- 2672 ------------------------------------- 2673 2674 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is 2675 2676 function Check_For_Warnings (N : Node_Id) return Traverse_Result; 2677 -- Function used to check one node to see if it is or was originally 2678 -- a reference to an entity for which Warnings are off. If so, Abandon 2679 -- is returned, otherwise OK_Orig is returned to continue the traversal 2680 -- of the original expression. 2681 2682 function Traverse is new Traverse_Func (Check_For_Warnings); 2683 -- Function used to traverse tree looking for warnings 2684 2685 ------------------------ 2686 -- Check_For_Warnings -- 2687 ------------------------ 2688 2689 function Check_For_Warnings (N : Node_Id) return Traverse_Result is 2690 R : constant Node_Id := Original_Node (N); 2691 2692 begin 2693 if Nkind (R) in N_Has_Entity 2694 and then Present (Entity (R)) 2695 and then Has_Warnings_Off (Entity (R)) 2696 then 2697 return Abandon; 2698 else 2699 return OK_Orig; 2700 end if; 2701 end Check_For_Warnings; 2702 2703 -- Start of processing for Operand_Has_Warnings_Suppressed 2704 2705 begin 2706 return Traverse (N) = Abandon; 2707 2708 -- If any exception occurs, then something has gone wrong, and this is 2709 -- only a minor aesthetic issue anyway, so just say we did not find what 2710 -- we are looking for, rather than blow up. 2711 2712 exception 2713 when others => 2714 return False; 2715 end Operand_Has_Warnings_Suppressed; 2716 2717 ----------------------------------------- 2718 -- Output_Non_Modified_In_Out_Warnings -- 2719 ----------------------------------------- 2720 2721 procedure Output_Non_Modified_In_Out_Warnings is 2722 2723 function No_Warn_On_In_Out (E : Entity_Id) return Boolean; 2724 -- Given a formal parameter entity E, determines if there is a reason to 2725 -- suppress IN OUT warnings (not modified, could be IN) for formals of 2726 -- the subprogram. We suppress these warnings if Warnings Off is set, or 2727 -- if we have seen the address of the subprogram being taken, or if the 2728 -- subprogram is used as a generic actual (in the latter cases the 2729 -- context may force use of IN OUT, even if the parameter is not 2730 -- modifies for this particular case. 2731 2732 ----------------------- 2733 -- No_Warn_On_In_Out -- 2734 ----------------------- 2735 2736 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is 2737 S : constant Entity_Id := Scope (E); 2738 SE : constant Entity_Id := Spec_Entity (E); 2739 2740 begin 2741 -- Do not warn if address is taken, since funny business may be going 2742 -- on in treating the parameter indirectly as IN OUT. 2743 2744 if Address_Taken (S) 2745 or else (Present (SE) and then Address_Taken (Scope (SE))) 2746 then 2747 return True; 2748 2749 -- Do not warn if used as a generic actual, since the generic may be 2750 -- what is forcing the use of an "unnecessary" IN OUT. 2751 2752 elsif Used_As_Generic_Actual (S) 2753 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE))) 2754 then 2755 return True; 2756 2757 -- Else test warnings off 2758 2759 elsif Warnings_Off_Check_Spec (S) then 2760 return True; 2761 2762 -- All tests for suppressing warning failed 2763 2764 else 2765 return False; 2766 end if; 2767 end No_Warn_On_In_Out; 2768 2769 -- Start of processing for Output_Non_Modified_In_Out_Warnings 2770 2771 begin 2772 -- Loop through entities for which a warning may be needed 2773 2774 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop 2775 declare 2776 E1 : constant Entity_Id := In_Out_Warnings.Table (J); 2777 2778 begin 2779 -- Suppress warning in specific cases (see details in comments for 2780 -- No_Warn_On_In_Out), or if there is a pragma Unmodified. 2781 2782 if Has_Pragma_Unmodified_Check_Spec (E1) 2783 or else No_Warn_On_In_Out (E1) 2784 then 2785 null; 2786 2787 -- Here we generate the warning 2788 2789 else 2790 -- If -gnatwc is set then output message that we could be IN 2791 2792 if not Is_Trivial_Subprogram (Scope (E1)) then 2793 if Warn_On_Constant then 2794 Error_Msg_N 2795 ("?u?formal parameter & is not modified!", E1); 2796 Error_Msg_N 2797 ("\?u?mode could be IN instead of `IN OUT`!", E1); 2798 2799 -- We do not generate warnings for IN OUT parameters 2800 -- unless we have at least -gnatwu. This is deliberately 2801 -- inconsistent with the treatment of variables, but 2802 -- otherwise we get too many unexpected warnings in 2803 -- default mode. 2804 2805 elsif Check_Unreferenced then 2806 Error_Msg_N 2807 ("?u?formal parameter& is read but " 2808 & "never assigned!", E1); 2809 end if; 2810 end if; 2811 2812 -- Kill any other warnings on this entity, since this is the 2813 -- one that should dominate any other unreferenced warning. 2814 2815 Set_Warnings_Off (E1); 2816 end if; 2817 end; 2818 end loop; 2819 end Output_Non_Modified_In_Out_Warnings; 2820 2821 ---------------------------------------- 2822 -- Output_Obsolescent_Entity_Warnings -- 2823 ---------------------------------------- 2824 2825 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is 2826 P : constant Node_Id := Parent (N); 2827 S : Entity_Id; 2828 2829 begin 2830 S := Current_Scope; 2831 2832 -- Do not output message if we are the scope of standard. This means 2833 -- we have a reference from a context clause from when it is originally 2834 -- processed, and that's too early to tell whether it is an obsolescent 2835 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make 2836 -- sure that we have a later call when the scope is available. This test 2837 -- also eliminates all messages for use clauses, which is fine (we do 2838 -- not want messages for use clauses, since they are always redundant 2839 -- with respect to the associated with clause). 2840 2841 if S = Standard_Standard then 2842 return; 2843 end if; 2844 2845 -- Do not output message if we are in scope of an obsolescent package 2846 -- or subprogram. 2847 2848 loop 2849 if Is_Obsolescent (S) then 2850 return; 2851 end if; 2852 2853 S := Scope (S); 2854 exit when S = Standard_Standard; 2855 end loop; 2856 2857 -- Here we will output the message 2858 2859 Error_Msg_Sloc := Sloc (E); 2860 2861 -- Case of with clause 2862 2863 if Nkind (P) = N_With_Clause then 2864 if Ekind (E) = E_Package then 2865 Error_Msg_NE 2866 ("??with of obsolescent package& declared#", N, E); 2867 elsif Ekind (E) = E_Procedure then 2868 Error_Msg_NE 2869 ("??with of obsolescent procedure& declared#", N, E); 2870 else 2871 Error_Msg_NE 2872 ("??with of obsolescent function& declared#", N, E); 2873 end if; 2874 2875 -- If we do not have a with clause, then ignore any reference to an 2876 -- obsolescent package name. We only want to give the one warning of 2877 -- withing the package, not one each time it is used to qualify. 2878 2879 elsif Ekind (E) = E_Package then 2880 return; 2881 2882 -- Procedure call statement 2883 2884 elsif Nkind (P) = N_Procedure_Call_Statement then 2885 Error_Msg_NE 2886 ("??call to obsolescent procedure& declared#", N, E); 2887 2888 -- Function call 2889 2890 elsif Nkind (P) = N_Function_Call then 2891 Error_Msg_NE 2892 ("??call to obsolescent function& declared#", N, E); 2893 2894 -- Reference to obsolescent type 2895 2896 elsif Is_Type (E) then 2897 Error_Msg_NE 2898 ("??reference to obsolescent type& declared#", N, E); 2899 2900 -- Reference to obsolescent component 2901 2902 elsif Ekind_In (E, E_Component, E_Discriminant) then 2903 Error_Msg_NE 2904 ("??reference to obsolescent component& declared#", N, E); 2905 2906 -- Reference to obsolescent variable 2907 2908 elsif Ekind (E) = E_Variable then 2909 Error_Msg_NE 2910 ("??reference to obsolescent variable& declared#", N, E); 2911 2912 -- Reference to obsolescent constant 2913 2914 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then 2915 Error_Msg_NE 2916 ("??reference to obsolescent constant& declared#", N, E); 2917 2918 -- Reference to obsolescent enumeration literal 2919 2920 elsif Ekind (E) = E_Enumeration_Literal then 2921 Error_Msg_NE 2922 ("??reference to obsolescent enumeration literal& declared#", N, E); 2923 2924 -- Generic message for any other case we missed 2925 2926 else 2927 Error_Msg_NE 2928 ("??reference to obsolescent entity& declared#", N, E); 2929 end if; 2930 2931 -- Output additional warning if present 2932 2933 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop 2934 if Obsolescent_Warnings.Table (J).Ent = E then 2935 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg); 2936 Error_Msg_Strlen := Name_Len; 2937 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len); 2938 Error_Msg_N ("\\??~", N); 2939 exit; 2940 end if; 2941 end loop; 2942 end Output_Obsolescent_Entity_Warnings; 2943 2944 ---------------------------------- 2945 -- Output_Unreferenced_Messages -- 2946 ---------------------------------- 2947 2948 procedure Output_Unreferenced_Messages is 2949 begin 2950 for J in Unreferenced_Entities.First .. 2951 Unreferenced_Entities.Last 2952 loop 2953 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J)); 2954 end loop; 2955 end Output_Unreferenced_Messages; 2956 2957 ----------------------------------------- 2958 -- Output_Unused_Warnings_Off_Warnings -- 2959 ----------------------------------------- 2960 2961 procedure Output_Unused_Warnings_Off_Warnings is 2962 begin 2963 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop 2964 declare 2965 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J); 2966 N : Node_Id renames Wentry.N; 2967 E : Node_Id renames Wentry.E; 2968 2969 begin 2970 -- Turn off Warnings_Off, or we won't get the warning! 2971 2972 Set_Warnings_Off (E, False); 2973 2974 -- Nothing to do if pragma was used to suppress a general warning 2975 2976 if Warnings_Off_Used (E) then 2977 null; 2978 2979 -- If pragma was used both in unmodified and unreferenced contexts 2980 -- then that's as good as the general case, no warning. 2981 2982 elsif Warnings_Off_Used_Unmodified (E) 2983 and 2984 Warnings_Off_Used_Unreferenced (E) 2985 then 2986 null; 2987 2988 -- Used only in context where Unmodified would have worked 2989 2990 elsif Warnings_Off_Used_Unmodified (E) then 2991 Error_Msg_NE 2992 ("?W?could use Unmodified instead of " 2993 & "Warnings Off for &", Pragma_Identifier (N), E); 2994 2995 -- Used only in context where Unreferenced would have worked 2996 2997 elsif Warnings_Off_Used_Unreferenced (E) then 2998 Error_Msg_NE 2999 ("?W?could use Unreferenced instead of " 3000 & "Warnings Off for &", Pragma_Identifier (N), E); 3001 3002 -- Not used at all 3003 3004 else 3005 Error_Msg_NE 3006 ("?W?pragma Warnings Off for & unused, " 3007 & "could be omitted", N, E); 3008 end if; 3009 end; 3010 end loop; 3011 end Output_Unused_Warnings_Off_Warnings; 3012 3013 --------------------------- 3014 -- Referenced_Check_Spec -- 3015 --------------------------- 3016 3017 function Referenced_Check_Spec (E : Entity_Id) return Boolean is 3018 begin 3019 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3020 return Referenced (E) or else Referenced (Spec_Entity (E)); 3021 else 3022 return Referenced (E); 3023 end if; 3024 end Referenced_Check_Spec; 3025 3026 ---------------------------------- 3027 -- Referenced_As_LHS_Check_Spec -- 3028 ---------------------------------- 3029 3030 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is 3031 begin 3032 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3033 return Referenced_As_LHS (E) 3034 or else Referenced_As_LHS (Spec_Entity (E)); 3035 else 3036 return Referenced_As_LHS (E); 3037 end if; 3038 end Referenced_As_LHS_Check_Spec; 3039 3040 -------------------------------------------- 3041 -- Referenced_As_Out_Parameter_Check_Spec -- 3042 -------------------------------------------- 3043 3044 function Referenced_As_Out_Parameter_Check_Spec 3045 (E : Entity_Id) return Boolean 3046 is 3047 begin 3048 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3049 return Referenced_As_Out_Parameter (E) 3050 or else Referenced_As_Out_Parameter (Spec_Entity (E)); 3051 else 3052 return Referenced_As_Out_Parameter (E); 3053 end if; 3054 end Referenced_As_Out_Parameter_Check_Spec; 3055 3056 ----------------------------- 3057 -- Warn_On_Known_Condition -- 3058 ----------------------------- 3059 3060 procedure Warn_On_Known_Condition (C : Node_Id) is 3061 P : Node_Id; 3062 Orig : constant Node_Id := Original_Node (C); 3063 Test_Result : Boolean; 3064 3065 function Is_Known_Branch return Boolean; 3066 -- If the type of the condition is Boolean, the constant value of the 3067 -- condition is a boolean literal. If the type is a derived boolean 3068 -- type, the constant is wrapped in a type conversion of the derived 3069 -- literal. If the value of the condition is not a literal, no warnings 3070 -- can be produced. This function returns True if the result can be 3071 -- determined, and Test_Result is set True/False accordingly. Otherwise 3072 -- False is returned, and Test_Result is unchanged. 3073 3074 procedure Track (N : Node_Id; Loc : Node_Id); 3075 -- Adds continuation warning(s) pointing to reason (assignment or test) 3076 -- for the operand of the conditional having a known value (or at least 3077 -- enough is known about the value to issue the warning). N is the node 3078 -- which is judged to have a known value. Loc is the warning location. 3079 3080 --------------------- 3081 -- Is_Known_Branch -- 3082 --------------------- 3083 3084 function Is_Known_Branch return Boolean is 3085 begin 3086 if Etype (C) = Standard_Boolean 3087 and then Is_Entity_Name (C) 3088 and then 3089 (Entity (C) = Standard_False or else Entity (C) = Standard_True) 3090 then 3091 Test_Result := Entity (C) = Standard_True; 3092 return True; 3093 3094 elsif Is_Boolean_Type (Etype (C)) 3095 and then Nkind (C) = N_Unchecked_Type_Conversion 3096 and then Is_Entity_Name (Expression (C)) 3097 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal 3098 then 3099 Test_Result := 3100 Chars (Entity (Expression (C))) = Chars (Standard_True); 3101 return True; 3102 3103 else 3104 return False; 3105 end if; 3106 end Is_Known_Branch; 3107 3108 ----------- 3109 -- Track -- 3110 ----------- 3111 3112 procedure Track (N : Node_Id; Loc : Node_Id) is 3113 Nod : constant Node_Id := Original_Node (N); 3114 3115 begin 3116 if Nkind (Nod) in N_Op_Compare then 3117 Track (Left_Opnd (Nod), Loc); 3118 Track (Right_Opnd (Nod), Loc); 3119 3120 elsif Is_Entity_Name (Nod) 3121 and then Is_Object (Entity (Nod)) 3122 then 3123 declare 3124 CV : constant Node_Id := Current_Value (Entity (Nod)); 3125 3126 begin 3127 if Present (CV) then 3128 Error_Msg_Sloc := Sloc (CV); 3129 3130 if Nkind (CV) not in N_Subexpr then 3131 Error_Msg_N ("\\?(see test #)", Loc); 3132 3133 elsif Nkind (Parent (CV)) = 3134 N_Case_Statement_Alternative 3135 then 3136 Error_Msg_N ("\\?(see case alternative #)", Loc); 3137 3138 else 3139 Error_Msg_N ("\\?(see assignment #)", Loc); 3140 end if; 3141 end if; 3142 end; 3143 end if; 3144 end Track; 3145 3146 -- Start of processing for Warn_On_Known_Condition 3147 3148 begin 3149 -- Adjust SCO condition if from source 3150 3151 if Generate_SCO 3152 and then Comes_From_Source (Orig) 3153 and then Is_Known_Branch 3154 then 3155 declare 3156 Atrue : Boolean; 3157 3158 begin 3159 Atrue := Test_Result; 3160 3161 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then 3162 Atrue := not Atrue; 3163 end if; 3164 3165 Set_SCO_Condition (Orig, Atrue); 3166 end; 3167 end if; 3168 3169 -- Argument replacement in an inlined body can make conditions static. 3170 -- Do not emit warnings in this case. 3171 3172 if In_Inlined_Body then 3173 return; 3174 end if; 3175 3176 if Constant_Condition_Warnings 3177 and then Is_Known_Branch 3178 and then Comes_From_Source (Orig) 3179 and then not In_Instance 3180 then 3181 -- Don't warn if comparison of result of attribute against a constant 3182 -- value, since this is likely legitimate conditional compilation. 3183 3184 if Nkind (Orig) in N_Op_Compare 3185 and then Compile_Time_Known_Value (Right_Opnd (Orig)) 3186 and then Nkind (Original_Node (Left_Opnd (Orig))) = 3187 N_Attribute_Reference 3188 then 3189 return; 3190 end if; 3191 3192 -- See if this is in a statement or a declaration 3193 3194 P := Parent (C); 3195 loop 3196 -- If tree is not attached, do not issue warning (this is very 3197 -- peculiar, and probably arises from some other error condition) 3198 3199 if No (P) then 3200 return; 3201 3202 -- If we are in a declaration, then no warning, since in practice 3203 -- conditionals in declarations are used for intended tests which 3204 -- may be known at compile time, e.g. things like 3205 3206 -- x : constant Integer := 2 + (Word'Size = 32); 3207 3208 -- And a warning is annoying in such cases 3209 3210 elsif Nkind (P) in N_Declaration 3211 or else 3212 Nkind (P) in N_Later_Decl_Item 3213 then 3214 return; 3215 3216 -- Don't warn in assert or check pragma, since presumably tests in 3217 -- such a context are very definitely intended, and might well be 3218 -- known at compile time. Note that we have to test the original 3219 -- node, since assert pragmas get rewritten at analysis time. 3220 3221 elsif Nkind (Original_Node (P)) = N_Pragma 3222 and then (Pragma_Name (Original_Node (P)) = Name_Assert 3223 or else 3224 Pragma_Name (Original_Node (P)) = Name_Check) 3225 then 3226 return; 3227 end if; 3228 3229 exit when Is_Statement (P); 3230 P := Parent (P); 3231 end loop; 3232 3233 -- Here we issue the warning unless some sub-operand has warnings 3234 -- set off, in which case we suppress the warning for the node. If 3235 -- the original expression is an inequality, it has been expanded 3236 -- into a negation, and the value of the original expression is the 3237 -- negation of the equality. If the expression is an entity that 3238 -- appears within a negation, it is clearer to flag the negation 3239 -- itself, and report on its constant value. 3240 3241 if not Operand_Has_Warnings_Suppressed (C) then 3242 declare 3243 True_Branch : Boolean := Test_Result; 3244 Cond : Node_Id := C; 3245 3246 begin 3247 if Present (Parent (C)) 3248 and then Nkind (Parent (C)) = N_Op_Not 3249 then 3250 True_Branch := not True_Branch; 3251 Cond := Parent (C); 3252 end if; 3253 3254 if True_Branch then 3255 if Is_Entity_Name (Original_Node (C)) 3256 and then Nkind (Cond) /= N_Op_Not 3257 then 3258 Error_Msg_NE 3259 ("object & is always True?c?", Cond, Original_Node (C)); 3260 Track (Original_Node (C), Cond); 3261 3262 else 3263 Error_Msg_N ("condition is always True?c?", Cond); 3264 Track (Cond, Cond); 3265 end if; 3266 3267 else 3268 Error_Msg_N ("condition is always False?c?", Cond); 3269 Track (Cond, Cond); 3270 end if; 3271 end; 3272 end if; 3273 end if; 3274 end Warn_On_Known_Condition; 3275 3276 --------------------------------------- 3277 -- Warn_On_Modified_As_Out_Parameter -- 3278 --------------------------------------- 3279 3280 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is 3281 begin 3282 return 3283 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E)) 3284 or else Warn_On_All_Unread_Out_Parameters; 3285 end Warn_On_Modified_As_Out_Parameter; 3286 3287 --------------------------------- 3288 -- Warn_On_Overlapping_Actuals -- 3289 --------------------------------- 3290 3291 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is 3292 Act1, Act2 : Node_Id; 3293 Form1, Form2 : Entity_Id; 3294 3295 function Is_Covered_Formal (Formal : Node_Id) return Boolean; 3296 -- Return True if Formal is covered by the rule 3297 3298 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean; 3299 -- Two names are known to refer to the same object if the two names 3300 -- are known to denote the same object; or one of the names is a 3301 -- selected_component, indexed_component, or slice and its prefix is 3302 -- known to refer to the same object as the other name; or one of the 3303 -- two names statically denotes a renaming declaration whose renamed 3304 -- object_name is known to refer to the same object as the other name 3305 -- (RM 6.4.1(6.11/3)) 3306 3307 ----------------------- 3308 -- Refer_Same_Object -- 3309 ----------------------- 3310 3311 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is 3312 begin 3313 return Denotes_Same_Object (Act1, Act2) 3314 or else Denotes_Same_Prefix (Act1, Act2); 3315 end Refer_Same_Object; 3316 3317 ----------------------- 3318 -- Is_Covered_Formal -- 3319 ----------------------- 3320 3321 function Is_Covered_Formal (Formal : Node_Id) return Boolean is 3322 begin 3323 return 3324 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter) 3325 and then (Is_Elementary_Type (Etype (Formal)) 3326 or else Is_Record_Type (Etype (Formal)) 3327 or else Is_Array_Type (Etype (Formal))); 3328 end Is_Covered_Formal; 3329 3330 begin 3331 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then 3332 return; 3333 end if; 3334 3335 -- Exclude calls rewritten as enumeration literals 3336 3337 if Nkind (N) not in N_Subprogram_Call 3338 and then Nkind (N) /= N_Entry_Call_Statement 3339 then 3340 return; 3341 end if; 3342 3343 -- If a call C has two or more parameters of mode in out or out that are 3344 -- of an elementary type, then the call is legal only if for each name 3345 -- N that is passed as a parameter of mode in out or out to the call C, 3346 -- there is no other name among the other parameters of mode in out or 3347 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3)) 3348 3349 -- If appropriate warning switch is set, we also report warnings on 3350 -- overlapping parameters that are record types or array types. 3351 3352 Form1 := First_Formal (Subp); 3353 Act1 := First_Actual (N); 3354 while Present (Form1) and then Present (Act1) loop 3355 if Is_Covered_Formal (Form1) then 3356 Form2 := First_Formal (Subp); 3357 Act2 := First_Actual (N); 3358 while Present (Form2) and then Present (Act2) loop 3359 if Form1 /= Form2 3360 and then Is_Covered_Formal (Form2) 3361 and then Refer_Same_Object (Act1, Act2) 3362 then 3363 -- Guard against previous errors 3364 3365 if Error_Posted (N) 3366 or else No (Etype (Act1)) 3367 or else No (Etype (Act2)) 3368 then 3369 null; 3370 3371 -- If the actual is a function call in prefix notation, 3372 -- there is no real overlap. 3373 3374 elsif Nkind (Act2) = N_Function_Call then 3375 null; 3376 3377 -- If type is not by-copy, assume that aliasing is intended 3378 3379 elsif 3380 Present (Underlying_Type (Etype (Form1))) 3381 and then 3382 (Is_By_Reference_Type (Underlying_Type (Etype (Form1))) 3383 or else 3384 Convention (Underlying_Type (Etype (Form1))) = 3385 Convention_Ada_Pass_By_Reference) 3386 then 3387 null; 3388 3389 -- Under Ada 2012 we only report warnings on overlapping 3390 -- arrays and record types if switch is set. 3391 3392 elsif Ada_Version >= Ada_2012 3393 and then not Is_Elementary_Type (Etype (Form1)) 3394 and then not Warn_On_Overlap 3395 then 3396 null; 3397 3398 -- Here we may need to issue message 3399 3400 else 3401 Error_Msg_Warn := 3402 Ada_Version < Ada_2012 3403 or else not Is_Elementary_Type (Etype (Form1)); 3404 3405 declare 3406 Act : Node_Id; 3407 Form : Entity_Id; 3408 3409 begin 3410 -- Find matching actual 3411 3412 Act := First_Actual (N); 3413 Form := First_Formal (Subp); 3414 while Act /= Act2 loop 3415 Next_Formal (Form); 3416 Next_Actual (Act); 3417 end loop; 3418 3419 if Is_Elementary_Type (Etype (Act1)) 3420 and then Ekind (Form2) = E_In_Parameter 3421 then 3422 null; -- No real aliasing 3423 3424 elsif Is_Elementary_Type (Etype (Act2)) 3425 and then Ekind (Form2) = E_In_Parameter 3426 then 3427 null; -- Ditto 3428 3429 -- If the call was written in prefix notation, and 3430 -- thus its prefix before rewriting was a selected 3431 -- component, count only visible actuals in the call. 3432 3433 elsif Is_Entity_Name (First_Actual (N)) 3434 and then Nkind (Original_Node (N)) = Nkind (N) 3435 and then Nkind (Name (Original_Node (N))) = 3436 N_Selected_Component 3437 and then 3438 Is_Entity_Name (Prefix (Name (Original_Node (N)))) 3439 and then 3440 Entity (Prefix (Name (Original_Node (N)))) = 3441 Entity (First_Actual (N)) 3442 then 3443 if Act1 = First_Actual (N) then 3444 Error_Msg_FE 3445 ("`IN OUT` prefix overlaps with " 3446 & "actual for&?I?", Act1, Form); 3447 3448 else 3449 -- For greater clarity, give name of formal 3450 3451 Error_Msg_Node_2 := Form; 3452 Error_Msg_FE 3453 ("writable actual for & overlaps with " 3454 & "actual for&?I?", Act1, Form); 3455 end if; 3456 3457 else 3458 Error_Msg_Node_2 := Form; 3459 Error_Msg_FE 3460 ("writable actual for & overlaps with " 3461 & "actual for&?I?", Act1, Form1); 3462 end if; 3463 end; 3464 end if; 3465 3466 return; 3467 end if; 3468 3469 Next_Formal (Form2); 3470 Next_Actual (Act2); 3471 end loop; 3472 end if; 3473 3474 Next_Formal (Form1); 3475 Next_Actual (Act1); 3476 end loop; 3477 end Warn_On_Overlapping_Actuals; 3478 3479 ------------------------------ 3480 -- Warn_On_Suspicious_Index -- 3481 ------------------------------ 3482 3483 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is 3484 3485 Low_Bound : Uint; 3486 -- Set to lower bound for a suspicious type 3487 3488 Ent : Entity_Id; 3489 -- Entity for array reference 3490 3491 Typ : Entity_Id; 3492 -- Array type 3493 3494 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean; 3495 -- Tests to see if Typ is a type for which we may have a suspicious 3496 -- index, namely an unconstrained array type, whose lower bound is 3497 -- either zero or one. If so, True is returned, and Low_Bound is set 3498 -- to this lower bound. If not, False is returned, and Low_Bound is 3499 -- undefined on return. 3500 -- 3501 -- For now, we limit this to standard string types, so any other 3502 -- unconstrained types return False. We may change our minds on this 3503 -- later on, but strings seem the most important case. 3504 3505 procedure Test_Suspicious_Index; 3506 -- Test if index is of suspicious type and if so, generate warning 3507 3508 ------------------------ 3509 -- Is_Suspicious_Type -- 3510 ------------------------ 3511 3512 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is 3513 LB : Node_Id; 3514 3515 begin 3516 if Is_Array_Type (Typ) 3517 and then not Is_Constrained (Typ) 3518 and then Number_Dimensions (Typ) = 1 3519 and then (Root_Type (Typ) = Standard_String 3520 or else 3521 Root_Type (Typ) = Standard_Wide_String 3522 or else 3523 Root_Type (Typ) = Standard_Wide_Wide_String) 3524 and then not Has_Warnings_Off (Typ) 3525 then 3526 LB := Type_Low_Bound (Etype (First_Index (Typ))); 3527 3528 if Compile_Time_Known_Value (LB) then 3529 Low_Bound := Expr_Value (LB); 3530 return Low_Bound = Uint_0 or else Low_Bound = Uint_1; 3531 end if; 3532 end if; 3533 3534 return False; 3535 end Is_Suspicious_Type; 3536 3537 --------------------------- 3538 -- Test_Suspicious_Index -- 3539 --------------------------- 3540 3541 procedure Test_Suspicious_Index is 3542 3543 function Length_Reference (N : Node_Id) return Boolean; 3544 -- Check if node N is of the form Name'Length 3545 3546 procedure Warn1; 3547 -- Generate first warning line 3548 3549 ---------------------- 3550 -- Length_Reference -- 3551 ---------------------- 3552 3553 function Length_Reference (N : Node_Id) return Boolean is 3554 R : constant Node_Id := Original_Node (N); 3555 begin 3556 return 3557 Nkind (R) = N_Attribute_Reference 3558 and then Attribute_Name (R) = Name_Length 3559 and then Is_Entity_Name (Prefix (R)) 3560 and then Entity (Prefix (R)) = Ent; 3561 end Length_Reference; 3562 3563 ----------- 3564 -- Warn1 -- 3565 ----------- 3566 3567 procedure Warn1 is 3568 begin 3569 Error_Msg_Uint_1 := Low_Bound; 3570 Error_Msg_FE -- CODEFIX 3571 ("?w?index for& may assume lower bound of^", X, Ent); 3572 end Warn1; 3573 3574 -- Start of processing for Test_Suspicious_Index 3575 3576 begin 3577 -- Nothing to do if subscript does not come from source (we don't 3578 -- want to give garbage warnings on compiler expanded code, e.g. the 3579 -- loops generated for slice assignments. Such junk warnings would 3580 -- be placed on source constructs with no subscript in sight!) 3581 3582 if not Comes_From_Source (Original_Node (X)) then 3583 return; 3584 end if; 3585 3586 -- Case where subscript is a constant integer 3587 3588 if Nkind (X) = N_Integer_Literal then 3589 Warn1; 3590 3591 -- Case where original form of subscript is an integer literal 3592 3593 if Nkind (Original_Node (X)) = N_Integer_Literal then 3594 if Intval (X) = Low_Bound then 3595 Error_Msg_FE -- CODEFIX 3596 ("\?w?suggested replacement: `&''First`", X, Ent); 3597 else 3598 Error_Msg_Uint_1 := Intval (X) - Low_Bound; 3599 Error_Msg_FE -- CODEFIX 3600 ("\?w?suggested replacement: `&''First + ^`", X, Ent); 3601 3602 end if; 3603 3604 -- Case where original form of subscript is more complex 3605 3606 else 3607 -- Build string X'First - 1 + expression where the expression 3608 -- is the original subscript. If the expression starts with "1 3609 -- + ", then the "- 1 + 1" is elided. 3610 3611 Error_Msg_String (1 .. 13) := "'First - 1 + "; 3612 Error_Msg_Strlen := 13; 3613 3614 declare 3615 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X))); 3616 Tref : constant Source_Buffer_Ptr := 3617 Source_Text (Get_Source_File_Index (Sref)); 3618 -- Tref (Sref) is used to scan the subscript 3619 3620 Pctr : Natural; 3621 -- Parentheses counter when scanning subscript 3622 3623 begin 3624 -- Tref (Sref) points to start of subscript 3625 3626 -- Elide - 1 if subscript starts with 1 + 3627 3628 if Tref (Sref .. Sref + 2) = "1 +" then 3629 Error_Msg_Strlen := Error_Msg_Strlen - 6; 3630 Sref := Sref + 2; 3631 3632 elsif Tref (Sref .. Sref + 1) = "1+" then 3633 Error_Msg_Strlen := Error_Msg_Strlen - 6; 3634 Sref := Sref + 1; 3635 end if; 3636 3637 -- Now we will copy the subscript to the string buffer 3638 3639 Pctr := 0; 3640 loop 3641 -- Count parens, exit if terminating right paren. Note 3642 -- check to ignore paren appearing as character literal. 3643 3644 if Tref (Sref + 1) = ''' 3645 and then 3646 Tref (Sref - 1) = ''' 3647 then 3648 null; 3649 else 3650 if Tref (Sref) = '(' then 3651 Pctr := Pctr + 1; 3652 elsif Tref (Sref) = ')' then 3653 exit when Pctr = 0; 3654 Pctr := Pctr - 1; 3655 end if; 3656 end if; 3657 3658 -- Done if terminating double dot (slice case) 3659 3660 exit when Pctr = 0 3661 and then (Tref (Sref .. Sref + 1) = ".." 3662 or else 3663 Tref (Sref .. Sref + 2) = " .."); 3664 3665 -- Quit if we have hit EOF character, something wrong 3666 3667 if Tref (Sref) = EOF then 3668 return; 3669 end if; 3670 3671 -- String literals are too much of a pain to handle 3672 3673 if Tref (Sref) = '"' or else Tref (Sref) = '%' then 3674 return; 3675 end if; 3676 3677 -- If we have a 'Range reference, then this is a case 3678 -- where we cannot easily give a replacement. Don't try! 3679 3680 if Tref (Sref .. Sref + 4) = "range" 3681 and then Tref (Sref - 1) < 'A' 3682 and then Tref (Sref + 5) < 'A' 3683 then 3684 return; 3685 end if; 3686 3687 -- Else store next character 3688 3689 Error_Msg_Strlen := Error_Msg_Strlen + 1; 3690 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref); 3691 Sref := Sref + 1; 3692 3693 -- If we get more than 40 characters then the expression 3694 -- is too long to copy, or something has gone wrong. In 3695 -- either case, just skip the attempt at a suggested fix. 3696 3697 if Error_Msg_Strlen > 40 then 3698 return; 3699 end if; 3700 end loop; 3701 end; 3702 3703 -- Replacement subscript is now in string buffer 3704 3705 Error_Msg_FE -- CODEFIX 3706 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent); 3707 end if; 3708 3709 -- Case where subscript is of the form X'Length 3710 3711 elsif Length_Reference (X) then 3712 Warn1; 3713 Error_Msg_Node_2 := Ent; 3714 Error_Msg_FE 3715 ("\?w?suggest replacement of `&''Length` by `&''Last`", 3716 X, Ent); 3717 3718 -- Case where subscript is of the form X'Length - expression 3719 3720 elsif Nkind (X) = N_Op_Subtract 3721 and then Length_Reference (Left_Opnd (X)) 3722 then 3723 Warn1; 3724 Error_Msg_Node_2 := Ent; 3725 Error_Msg_FE 3726 ("\?w?suggest replacement of `&''Length` by `&''Last`", 3727 Left_Opnd (X), Ent); 3728 end if; 3729 end Test_Suspicious_Index; 3730 3731 -- Start of processing for Warn_On_Suspicious_Index 3732 3733 begin 3734 -- Only process if warnings activated 3735 3736 if Warn_On_Assumed_Low_Bound then 3737 3738 -- Test if array is simple entity name 3739 3740 if Is_Entity_Name (Name) then 3741 3742 -- Test if array is parameter of unconstrained string type 3743 3744 Ent := Entity (Name); 3745 Typ := Etype (Ent); 3746 3747 if Is_Formal (Ent) 3748 and then Is_Suspicious_Type (Typ) 3749 and then not Low_Bound_Tested (Ent) 3750 then 3751 Test_Suspicious_Index; 3752 end if; 3753 end if; 3754 end if; 3755 end Warn_On_Suspicious_Index; 3756 3757 -------------------------------------- 3758 -- Warn_On_Unassigned_Out_Parameter -- 3759 -------------------------------------- 3760 3761 procedure Warn_On_Unassigned_Out_Parameter 3762 (Return_Node : Node_Id; 3763 Scope_Id : Entity_Id) 3764 is 3765 Form : Entity_Id; 3766 Form2 : Entity_Id; 3767 3768 begin 3769 -- Ignore if procedure or return statement does not come from source 3770 3771 if not Comes_From_Source (Scope_Id) 3772 or else not Comes_From_Source (Return_Node) 3773 then 3774 return; 3775 end if; 3776 3777 -- Loop through formals 3778 3779 Form := First_Formal (Scope_Id); 3780 while Present (Form) loop 3781 3782 -- We are only interested in OUT parameters that come from source 3783 -- and are never set in the source, and furthermore only in scalars 3784 -- since non-scalars generate too many false positives. 3785 3786 if Ekind (Form) = E_Out_Parameter 3787 and then Never_Set_In_Source_Check_Spec (Form) 3788 and then Is_Scalar_Type (Etype (Form)) 3789 and then not Present (Unset_Reference (Form)) 3790 then 3791 -- Before we issue the warning, an add ad hoc defence against the 3792 -- most common case of false positives with this warning which is 3793 -- the case where there is a Boolean OUT parameter that has been 3794 -- set, and whose meaning is "ignore the values of the other 3795 -- parameters". We can't of course reliably tell this case at 3796 -- compile time, but the following test kills a lot of false 3797 -- positives, without generating a significant number of false 3798 -- negatives (missed real warnings). 3799 3800 Form2 := First_Formal (Scope_Id); 3801 while Present (Form2) loop 3802 if Ekind (Form2) = E_Out_Parameter 3803 and then Root_Type (Etype (Form2)) = Standard_Boolean 3804 and then not Never_Set_In_Source_Check_Spec (Form2) 3805 then 3806 return; 3807 end if; 3808 3809 Next_Formal (Form2); 3810 end loop; 3811 3812 -- Here all conditions are met, record possible unset reference 3813 3814 Set_Unset_Reference (Form, Return_Node); 3815 end if; 3816 3817 Next_Formal (Form); 3818 end loop; 3819 end Warn_On_Unassigned_Out_Parameter; 3820 3821 --------------------------------- 3822 -- Warn_On_Unreferenced_Entity -- 3823 --------------------------------- 3824 3825 procedure Warn_On_Unreferenced_Entity 3826 (Spec_E : Entity_Id; 3827 Body_E : Entity_Id := Empty) 3828 is 3829 E : Entity_Id := Spec_E; 3830 3831 begin 3832 if not Referenced_Check_Spec (E) 3833 and then not Has_Pragma_Unreferenced_Check_Spec (E) 3834 and then not Warnings_Off_Check_Spec (E) 3835 then 3836 case Ekind (E) is 3837 when E_Variable => 3838 3839 -- Case of variable that is assigned but not read. We suppress 3840 -- the message if the variable is volatile, has an address 3841 -- clause, is aliased, or is a renaming, or is imported. 3842 3843 if Referenced_As_LHS_Check_Spec (E) 3844 and then No (Address_Clause (E)) 3845 and then not Is_Volatile (E) 3846 then 3847 if Warn_On_Modified_Unread 3848 and then not Is_Imported (E) 3849 and then not Is_Aliased (E) 3850 and then No (Renamed_Object (E)) 3851 then 3852 if not Has_Pragma_Unmodified_Check_Spec (E) then 3853 Error_Msg_N -- CODEFIX 3854 ("?u?variable & is assigned but never read!", E); 3855 end if; 3856 3857 Set_Last_Assignment (E, Empty); 3858 end if; 3859 3860 -- Normal case of neither assigned nor read (exclude variables 3861 -- referenced as out parameters, since we already generated 3862 -- appropriate warnings at the call point in this case). 3863 3864 elsif not Referenced_As_Out_Parameter (E) then 3865 3866 -- We suppress the message for types for which a valid 3867 -- pragma Unreferenced_Objects has been given, otherwise 3868 -- we go ahead and give the message. 3869 3870 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then 3871 3872 -- Distinguish renamed case in message 3873 3874 if Present (Renamed_Object (E)) 3875 and then Comes_From_Source (Renamed_Object (E)) 3876 then 3877 Error_Msg_N -- CODEFIX 3878 ("?u?renamed variable & is not referenced!", E); 3879 else 3880 Error_Msg_N -- CODEFIX 3881 ("?u?variable & is not referenced!", E); 3882 end if; 3883 end if; 3884 end if; 3885 3886 when E_Constant => 3887 if Present (Renamed_Object (E)) 3888 and then Comes_From_Source (Renamed_Object (E)) 3889 then 3890 Error_Msg_N -- CODEFIX 3891 ("?u?renamed constant & is not referenced!", E); 3892 else 3893 Error_Msg_N -- CODEFIX 3894 ("?u?constant & is not referenced!", E); 3895 end if; 3896 3897 when E_In_Parameter | 3898 E_In_Out_Parameter => 3899 3900 -- Do not emit message for formals of a renaming, because 3901 -- they are never referenced explicitly. 3902 3903 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /= 3904 N_Subprogram_Renaming_Declaration 3905 then 3906 -- Suppress this message for an IN OUT parameter of a 3907 -- non-scalar type, since it is normal to have only an 3908 -- assignment in such a case. 3909 3910 if Ekind (E) = E_In_Parameter 3911 or else not Referenced_As_LHS_Check_Spec (E) 3912 or else Is_Scalar_Type (Etype (E)) 3913 then 3914 if Present (Body_E) then 3915 E := Body_E; 3916 end if; 3917 3918 if not Is_Trivial_Subprogram (Scope (E)) then 3919 Error_Msg_NE -- CODEFIX 3920 ("?u?formal parameter & is not referenced!", 3921 E, Spec_E); 3922 end if; 3923 end if; 3924 end if; 3925 3926 when E_Out_Parameter => 3927 null; 3928 3929 when E_Discriminant => 3930 Error_Msg_N ("?u?discriminant & is not referenced!", E); 3931 3932 when E_Named_Integer | 3933 E_Named_Real => 3934 Error_Msg_N -- CODEFIX 3935 ("?u?named number & is not referenced!", E); 3936 3937 when Formal_Object_Kind => 3938 Error_Msg_N -- CODEFIX 3939 ("?u?formal object & is not referenced!", E); 3940 3941 when E_Enumeration_Literal => 3942 Error_Msg_N -- CODEFIX 3943 ("?u?literal & is not referenced!", E); 3944 3945 when E_Function => 3946 Error_Msg_N -- CODEFIX 3947 ("?u?function & is not referenced!", E); 3948 3949 when E_Procedure => 3950 Error_Msg_N -- CODEFIX 3951 ("?u?procedure & is not referenced!", E); 3952 3953 when E_Package => 3954 Error_Msg_N -- CODEFIX 3955 ("?u?package & is not referenced!", E); 3956 3957 when E_Exception => 3958 Error_Msg_N -- CODEFIX 3959 ("?u?exception & is not referenced!", E); 3960 3961 when E_Label => 3962 Error_Msg_N -- CODEFIX 3963 ("?u?label & is not referenced!", E); 3964 3965 when E_Generic_Procedure => 3966 Error_Msg_N -- CODEFIX 3967 ("?u?generic procedure & is never instantiated!", E); 3968 3969 when E_Generic_Function => 3970 Error_Msg_N -- CODEFIX 3971 ("?u?generic function & is never instantiated!", E); 3972 3973 when Type_Kind => 3974 Error_Msg_N -- CODEFIX 3975 ("?u?type & is not referenced!", E); 3976 3977 when others => 3978 Error_Msg_N -- CODEFIX 3979 ("?u?& is not referenced!", E); 3980 end case; 3981 3982 -- Kill warnings on the entity on which the message has been posted 3983 3984 Set_Warnings_Off (E); 3985 end if; 3986 end Warn_On_Unreferenced_Entity; 3987 3988 -------------------------------- 3989 -- Warn_On_Useless_Assignment -- 3990 -------------------------------- 3991 3992 procedure Warn_On_Useless_Assignment 3993 (Ent : Entity_Id; 3994 N : Node_Id := Empty) 3995 is 3996 P : Node_Id; 3997 X : Node_Id; 3998 3999 function Check_Ref (N : Node_Id) return Traverse_Result; 4000 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to 4001 -- the entity in question is found. 4002 4003 function Test_No_Refs is new Traverse_Func (Check_Ref); 4004 4005 --------------- 4006 -- Check_Ref -- 4007 --------------- 4008 4009 function Check_Ref (N : Node_Id) return Traverse_Result is 4010 begin 4011 -- Check reference to our identifier. We use name equality here 4012 -- because the exception handlers have not yet been analyzed. This 4013 -- is not quite right, but it really does not matter that we fail 4014 -- to output the warning in some obscure cases of name clashes. 4015 4016 if Nkind (N) = N_Identifier 4017 and then Chars (N) = Chars (Ent) 4018 then 4019 return Abandon; 4020 else 4021 return OK; 4022 end if; 4023 end Check_Ref; 4024 4025 -- Start of processing for Warn_On_Useless_Assignment 4026 4027 begin 4028 -- Check if this is a case we want to warn on, a scalar or access 4029 -- variable with the last assignment field set, with warnings enabled, 4030 -- and which is not imported or exported. We also check that it is OK 4031 -- to capture the value. We are not going to capture any value, but 4032 -- the warning message depends on the same kind of conditions. 4033 4034 if Is_Assignable (Ent) 4035 and then not Is_Return_Object (Ent) 4036 and then Present (Last_Assignment (Ent)) 4037 and then not Is_Imported (Ent) 4038 and then not Is_Exported (Ent) 4039 and then Safe_To_Capture_Value (N, Ent) 4040 and then not Has_Pragma_Unreferenced_Check_Spec (Ent) 4041 then 4042 -- Before we issue the message, check covering exception handlers. 4043 -- Search up tree for enclosing statement sequences and handlers. 4044 4045 P := Parent (Last_Assignment (Ent)); 4046 while Present (P) loop 4047 4048 -- Something is really wrong if we don't find a handled statement 4049 -- sequence, so just suppress the warning. 4050 4051 if No (P) then 4052 Set_Last_Assignment (Ent, Empty); 4053 return; 4054 4055 -- When we hit a package/subprogram body, issue warning and exit 4056 4057 elsif Nkind (P) = N_Subprogram_Body 4058 or else Nkind (P) = N_Package_Body 4059 then 4060 -- Case of assigned value never referenced 4061 4062 if No (N) then 4063 declare 4064 LA : constant Node_Id := Last_Assignment (Ent); 4065 4066 begin 4067 -- Don't give this for OUT and IN OUT formals, since 4068 -- clearly caller may reference the assigned value. Also 4069 -- never give such warnings for internal variables. 4070 4071 if Ekind (Ent) = E_Variable 4072 and then not Is_Internal_Name (Chars (Ent)) 4073 then 4074 -- Give appropriate message, distinguishing between 4075 -- assignment statements and out parameters. 4076 4077 if Nkind_In (Parent (LA), N_Procedure_Call_Statement, 4078 N_Parameter_Association) 4079 then 4080 Error_Msg_NE 4081 ("?m?& modified by call, but value never " 4082 & "referenced", LA, Ent); 4083 4084 else 4085 Error_Msg_NE -- CODEFIX 4086 ("?m?useless assignment to&, value never " 4087 & "referenced!", LA, Ent); 4088 end if; 4089 end if; 4090 end; 4091 4092 -- Case of assigned value overwritten 4093 4094 else 4095 declare 4096 LA : constant Node_Id := Last_Assignment (Ent); 4097 4098 begin 4099 Error_Msg_Sloc := Sloc (N); 4100 4101 -- Give appropriate message, distinguishing between 4102 -- assignment statements and out parameters. 4103 4104 if Nkind_In (Parent (LA), N_Procedure_Call_Statement, 4105 N_Parameter_Association) 4106 then 4107 Error_Msg_NE 4108 ("?m?& modified by call, but value overwritten #!", 4109 LA, Ent); 4110 else 4111 Error_Msg_NE -- CODEFIX 4112 ("?m?useless assignment to&, value overwritten #!", 4113 LA, Ent); 4114 end if; 4115 end; 4116 end if; 4117 4118 -- Clear last assignment indication and we are done 4119 4120 Set_Last_Assignment (Ent, Empty); 4121 return; 4122 4123 -- Enclosing handled sequence of statements 4124 4125 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then 4126 4127 -- Check exception handlers present 4128 4129 if Present (Exception_Handlers (P)) then 4130 4131 -- If we are not at the top level, we regard an inner 4132 -- exception handler as a decisive indicator that we should 4133 -- not generate the warning, since the variable in question 4134 -- may be accessed after an exception in the outer block. 4135 4136 if Nkind (Parent (P)) /= N_Subprogram_Body 4137 and then Nkind (Parent (P)) /= N_Package_Body 4138 then 4139 Set_Last_Assignment (Ent, Empty); 4140 return; 4141 4142 -- Otherwise we are at the outer level. An exception 4143 -- handler is significant only if it references the 4144 -- variable in question, or if the entity in question 4145 -- is an OUT or IN OUT parameter, which which case 4146 -- the caller can reference it after the exception 4147 -- handler completes. 4148 4149 else 4150 if Is_Formal (Ent) then 4151 Set_Last_Assignment (Ent, Empty); 4152 return; 4153 4154 else 4155 X := First (Exception_Handlers (P)); 4156 while Present (X) loop 4157 if Test_No_Refs (X) = Abandon then 4158 Set_Last_Assignment (Ent, Empty); 4159 return; 4160 end if; 4161 4162 X := Next (X); 4163 end loop; 4164 end if; 4165 end if; 4166 end if; 4167 end if; 4168 4169 P := Parent (P); 4170 end loop; 4171 end if; 4172 end Warn_On_Useless_Assignment; 4173 4174 --------------------------------- 4175 -- Warn_On_Useless_Assignments -- 4176 --------------------------------- 4177 4178 procedure Warn_On_Useless_Assignments (E : Entity_Id) is 4179 Ent : Entity_Id; 4180 begin 4181 if Warn_On_Modified_Unread 4182 and then In_Extended_Main_Source_Unit (E) 4183 then 4184 Ent := First_Entity (E); 4185 while Present (Ent) loop 4186 Warn_On_Useless_Assignment (Ent); 4187 Next_Entity (Ent); 4188 end loop; 4189 end if; 4190 end Warn_On_Useless_Assignments; 4191 4192 ----------------------------- 4193 -- Warnings_Off_Check_Spec -- 4194 ----------------------------- 4195 4196 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is 4197 begin 4198 if Is_Formal (E) and then Present (Spec_Entity (E)) then 4199 4200 -- Note: use of OR here instead of OR ELSE is deliberate, we want 4201 -- to mess with flags on both entities. 4202 4203 return Has_Warnings_Off (E) 4204 or 4205 Has_Warnings_Off (Spec_Entity (E)); 4206 4207 else 4208 return Has_Warnings_Off (E); 4209 end if; 4210 end Warnings_Off_Check_Spec; 4211 4212end Sem_Warn; 4213