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) 1999-2015, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26with Atree; use Atree; 27with Debug; use Debug; 28with Einfo; use Einfo; 29with Errout; use Errout; 30with Exp_Code; use Exp_Code; 31with Fname; use Fname; 32with Lib; use Lib; 33with Lib.Xref; use Lib.Xref; 34with Namet; use Namet; 35with Nlists; use Nlists; 36with Opt; use Opt; 37with Par_SCO; use Par_SCO; 38with Rtsfind; use Rtsfind; 39with Sem; use Sem; 40with Sem_Ch8; use Sem_Ch8; 41with Sem_Aux; use Sem_Aux; 42with Sem_Eval; use Sem_Eval; 43with Sem_Prag; use Sem_Prag; 44with Sem_Util; use Sem_Util; 45with Sinfo; use Sinfo; 46with Sinput; use Sinput; 47with Snames; use Snames; 48with Stand; use Stand; 49with Stringt; use Stringt; 50with Uintp; use Uintp; 51 52package body Sem_Warn is 53 54 -- The following table collects Id's of entities that are potentially 55 -- unreferenced. See Check_Unset_Reference for further details. 56 -- ??? Check_Unset_Reference has zero information about this table. 57 58 package Unreferenced_Entities is new Table.Table ( 59 Table_Component_Type => Entity_Id, 60 Table_Index_Type => Nat, 61 Table_Low_Bound => 1, 62 Table_Initial => Alloc.Unreferenced_Entities_Initial, 63 Table_Increment => Alloc.Unreferenced_Entities_Increment, 64 Table_Name => "Unreferenced_Entities"); 65 66 -- The following table collects potential warnings for IN OUT parameters 67 -- that are referenced but not modified. These warnings are processed when 68 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings. 69 -- The reason that we defer output of these messages is that we want to 70 -- detect the case where the relevant procedure is used as a generic actual 71 -- in an instantiation, since we suppress the warnings in this case. The 72 -- flag Used_As_Generic_Actual will be set in this case, but only at the 73 -- point of usage. Similarly, we suppress the message if the address of the 74 -- procedure is taken, where the flag Address_Taken may be set later. 75 76 package In_Out_Warnings is new Table.Table ( 77 Table_Component_Type => Entity_Id, 78 Table_Index_Type => Nat, 79 Table_Low_Bound => 1, 80 Table_Initial => Alloc.In_Out_Warnings_Initial, 81 Table_Increment => Alloc.In_Out_Warnings_Increment, 82 Table_Name => "In_Out_Warnings"); 83 84 -------------------------------------------------------- 85 -- Handling of Warnings Off, Unmodified, Unreferenced -- 86 -------------------------------------------------------- 87 88 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must 89 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and 90 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo. 91 92 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary 93 -- warnings off pragma) mode, i.e. to avoid false negatives, the code 94 -- must follow some important rules. 95 96 -- Call these functions as late as possible, after completing all other 97 -- tests, just before the warnings is given. For example, don't write: 98 99 -- if not Has_Warnings_Off (E) 100 -- and then some-other-predicate-on-E then .. 101 102 -- Instead the following is preferred 103 104 -- if some-other-predicate-on-E 105 -- and then Has_Warnings_Off (E) 106 107 -- This way if some-other-predicate is false, we avoid a false indication 108 -- that a Warnings (Off, E) pragma was useful in preventing a warning. 109 110 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or 111 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the 112 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record 113 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In 114 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off, 115 -- and so a subsequent test is not needed anyway (though it is harmless). 116 117 ----------------------- 118 -- Local Subprograms -- 119 ----------------------- 120 121 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean; 122 -- This returns true if the entity E is declared within a generic package. 123 -- The point of this is to detect variables which are not assigned within 124 -- the generic, but might be assigned outside the package for any given 125 -- instance. These are cases where we leave the warnings to be posted for 126 -- the instance, when we will know more. 127 128 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id; 129 -- If E is a parameter entity for a subprogram body, then this function 130 -- returns the corresponding spec entity, if not, E is returned unchanged. 131 132 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean; 133 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal, 134 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is 135 -- a body formal, the setting of the flag in the corresponding spec is 136 -- also checked (and True returned if either flag is True). 137 138 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean; 139 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal, 140 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is 141 -- a body formal, the setting of the flag in the corresponding spec is 142 -- also checked (and True returned if either flag is True). 143 144 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean; 145 -- Tests Never_Set_In_Source status for entity E. If E is not a formal, 146 -- this is simply the setting of the flag Never_Set_In_Source. If E is 147 -- a body formal, the setting of the flag in the corresponding spec is 148 -- also checked (and False returned if either flag is False). 149 150 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean; 151 -- This function traverses the expression tree represented by the node N 152 -- and determines if any sub-operand is a reference to an entity for which 153 -- the Warnings_Off flag is set. True is returned if such an entity is 154 -- encountered, and False otherwise. 155 156 function Referenced_Check_Spec (E : Entity_Id) return Boolean; 157 -- Tests Referenced status for entity E. If E is not a formal, this is 158 -- simply the setting of the flag Referenced. If E is a body formal, the 159 -- setting of the flag in the corresponding spec is also checked (and True 160 -- returned if either flag is True). 161 162 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean; 163 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this 164 -- is simply the setting of the flag Referenced_As_LHS. If E is a body 165 -- formal, the setting of the flag in the corresponding spec is also 166 -- checked (and True returned if either flag is True). 167 168 function Referenced_As_Out_Parameter_Check_Spec 169 (E : Entity_Id) return Boolean; 170 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a 171 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E 172 -- is a body formal, the setting of the flag in the corresponding spec is 173 -- also checked (and True returned if either flag is True). 174 175 procedure Warn_On_Unreferenced_Entity 176 (Spec_E : Entity_Id; 177 Body_E : Entity_Id := Empty); 178 -- Output warnings for unreferenced entity E. For the case of an entry 179 -- formal, Body_E is the corresponding body entity for a particular 180 -- accept statement, and the message is posted on Body_E. In all other 181 -- cases, Body_E is ignored and must be Empty. 182 183 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean; 184 -- Returns True if Warnings_Off is set for the entity E or (in the case 185 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity. 186 187 -------------------------- 188 -- Check_Code_Statement -- 189 -------------------------- 190 191 procedure Check_Code_Statement (N : Node_Id) is 192 begin 193 -- If volatile, nothing to worry about 194 195 if Is_Asm_Volatile (N) then 196 return; 197 end if; 198 199 -- Warn if no input or no output 200 201 Setup_Asm_Inputs (N); 202 203 if No (Asm_Input_Value) then 204 Error_Msg_F 205 ("??code statement with no inputs should usually be Volatile!", N); 206 return; 207 end if; 208 209 Setup_Asm_Outputs (N); 210 211 if No (Asm_Output_Variable) then 212 Error_Msg_F 213 ("??code statement with no outputs should usually be Volatile!", N); 214 return; 215 end if; 216 end Check_Code_Statement; 217 218 --------------------------------- 219 -- Check_Infinite_Loop_Warning -- 220 --------------------------------- 221 222 -- The case we look for is a while loop which tests a local variable, where 223 -- there is no obvious direct or possible indirect update of the variable 224 -- within the body of the loop. 225 226 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is 227 Expression : Node_Id := Empty; 228 -- Set to WHILE or EXIT WHEN condition to be tested 229 230 Ref : Node_Id := Empty; 231 -- Reference in Expression to variable that might not be modified 232 -- in loop, indicating a possible infinite loop. 233 234 Var : Entity_Id := Empty; 235 -- Corresponding entity (entity of Ref) 236 237 Function_Call_Found : Boolean := False; 238 -- True if Find_Var found a function call in the condition 239 240 procedure Find_Var (N : Node_Id); 241 -- Inspect condition to see if it depends on a single entity reference. 242 -- If so, Ref is set to point to the reference node, and Var is set to 243 -- the referenced Entity. 244 245 function Has_Indirection (T : Entity_Id) return Boolean; 246 -- If the controlling variable is an access type, or is a record type 247 -- with access components, assume that it is changed indirectly and 248 -- suppress the warning. As a concession to low-level programming, in 249 -- particular within Declib, we also suppress warnings on a record 250 -- type that contains components of type Address or Short_Address. 251 252 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean; 253 -- Given an entity name, see if the name appears to have something to 254 -- do with I/O or network stuff, and if so, return True. Used to kill 255 -- some false positives on a heuristic basis that such functions will 256 -- likely have some strange side effect dependencies. A rather strange 257 -- test, but warning messages are in the heuristics business. 258 259 function Test_Ref (N : Node_Id) return Traverse_Result; 260 -- Test for reference to variable in question. Returns Abandon if 261 -- matching reference found. Used in instantiation of No_Ref_Found. 262 263 function No_Ref_Found is new Traverse_Func (Test_Ref); 264 -- Function to traverse body of procedure. Returns Abandon if matching 265 -- reference found. 266 267 -------------- 268 -- Find_Var -- 269 -------------- 270 271 procedure Find_Var (N : Node_Id) is 272 begin 273 -- Condition is a direct variable reference 274 275 if Is_Entity_Name (N) then 276 Ref := N; 277 Var := Entity (Ref); 278 279 -- Case of condition is a comparison with compile time known value 280 281 elsif Nkind (N) in N_Op_Compare then 282 if Compile_Time_Known_Value (Right_Opnd (N)) then 283 Find_Var (Left_Opnd (N)); 284 285 elsif Compile_Time_Known_Value (Left_Opnd (N)) then 286 Find_Var (Right_Opnd (N)); 287 288 -- Ignore any other comparison 289 290 else 291 return; 292 end if; 293 294 -- If condition is a negation, check its operand 295 296 elsif Nkind (N) = N_Op_Not then 297 Find_Var (Right_Opnd (N)); 298 299 -- Case of condition is function call 300 301 elsif Nkind (N) = N_Function_Call then 302 303 Function_Call_Found := True; 304 305 -- Forget it if function name is not entity, who knows what 306 -- we might be calling? 307 308 if not Is_Entity_Name (Name (N)) then 309 return; 310 311 -- Forget it if function name is suspicious. A strange test 312 -- but warning generation is in the heuristics business. 313 314 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then 315 return; 316 317 -- Forget it if warnings are suppressed on function entity 318 319 elsif Has_Warnings_Off (Entity (Name (N))) then 320 return; 321 end if; 322 323 -- OK, see if we have one argument 324 325 declare 326 PA : constant List_Id := Parameter_Associations (N); 327 328 begin 329 -- One argument, so check the argument 330 331 if Present (PA) and then List_Length (PA) = 1 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 (J = 1 or else Name_Buffer (J - 1) not in 'a' .. 'z') 418 and then 419 (J + Len > Name_Len 420 or else Name_Buffer (J + Len) not in 'a' .. 'z') 421 then 422 return True; 423 end if; 424 end loop; 425 426 return False; 427 end Substring_Present; 428 429 -- Start of processing for Is_Suspicious_Function_Name 430 431 begin 432 S := E; 433 while Present (S) and then S /= Standard_Standard loop 434 Get_Name_String (Chars (S)); 435 436 if Substring_Present ("io") 437 or else Substring_Present ("file") 438 or else Substring_Present ("network") 439 then 440 return True; 441 else 442 S := Scope (S); 443 end if; 444 end loop; 445 446 return False; 447 end Is_Suspicious_Function_Name; 448 449 -------------- 450 -- Test_Ref -- 451 -------------- 452 453 function Test_Ref (N : Node_Id) return Traverse_Result is 454 begin 455 -- Waste of time to look at the expression we are testing 456 457 if N = Expression then 458 return Skip; 459 460 -- Direct reference to variable in question 461 462 elsif Is_Entity_Name (N) 463 and then Present (Entity (N)) 464 and then Entity (N) = Var 465 then 466 -- If this is an lvalue, then definitely abandon, since 467 -- this could be a direct modification of the variable. 468 469 if May_Be_Lvalue (N) then 470 return Abandon; 471 end if; 472 473 -- If the condition contains a function call, we consider it may 474 -- be modified by side-effects from a procedure call. Otherwise, 475 -- we consider the condition may not be modified, although that 476 -- might happen if Variable is itself a by-reference parameter, 477 -- and the procedure called modifies the global object referred to 478 -- by Variable, but we actually prefer to issue a warning in this 479 -- odd case. Note that the case where the procedure called has 480 -- visibility over Variable is treated in another case below. 481 482 if Function_Call_Found then 483 declare 484 P : Node_Id; 485 486 begin 487 P := N; 488 loop 489 P := Parent (P); 490 exit when P = Loop_Statement; 491 492 -- Abandon if at procedure call, or something strange is 493 -- going on (perhaps a node with no parent that should 494 -- have one but does not?) As always, for a warning we 495 -- prefer to just abandon the warning than get into the 496 -- business of complaining about the tree structure here. 497 498 if No (P) 499 or else Nkind (P) = N_Procedure_Call_Statement 500 then 501 return Abandon; 502 end if; 503 end loop; 504 end; 505 end if; 506 507 -- Reference to variable renaming variable in question 508 509 elsif Is_Entity_Name (N) 510 and then Present (Entity (N)) 511 and then Ekind (Entity (N)) = E_Variable 512 and then Present (Renamed_Object (Entity (N))) 513 and then Is_Entity_Name (Renamed_Object (Entity (N))) 514 and then Entity (Renamed_Object (Entity (N))) = Var 515 and then May_Be_Lvalue (N) 516 then 517 return Abandon; 518 519 -- Call to subprogram 520 521 elsif Nkind (N) in N_Subprogram_Call then 522 523 -- If subprogram is within the scope of the entity we are dealing 524 -- with as the loop variable, then it could modify this parameter, 525 -- so we abandon in this case. In the case of a subprogram that is 526 -- not an entity we also abandon. The check for no entity being 527 -- present is a defense against previous errors. 528 529 if not Is_Entity_Name (Name (N)) 530 or else No (Entity (Name (N))) 531 or else Scope_Within (Entity (Name (N)), Scope (Var)) 532 then 533 return Abandon; 534 end if; 535 536 -- If any of the arguments are of type access to subprogram, then 537 -- we may have funny side effects, so no warning in this case. 538 539 declare 540 Actual : Node_Id; 541 begin 542 Actual := First_Actual (N); 543 while Present (Actual) loop 544 if Is_Access_Subprogram_Type (Etype (Actual)) then 545 return Abandon; 546 else 547 Next_Actual (Actual); 548 end if; 549 end loop; 550 end; 551 552 -- Declaration of the variable in question 553 554 elsif Nkind (N) = N_Object_Declaration 555 and then Defining_Identifier (N) = Var 556 then 557 return Abandon; 558 end if; 559 560 -- All OK, continue scan 561 562 return OK; 563 end Test_Ref; 564 565 -- Start of processing for Check_Infinite_Loop_Warning 566 567 begin 568 -- Skip processing if debug flag gnatd.w is set 569 570 if Debug_Flag_Dot_W then 571 return; 572 end if; 573 574 -- Deal with Iteration scheme present 575 576 declare 577 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement); 578 579 begin 580 if Present (Iter) then 581 582 -- While iteration 583 584 if Present (Condition (Iter)) then 585 586 -- Skip processing for while iteration with conditions actions, 587 -- since they make it too complicated to get the warning right. 588 589 if Present (Condition_Actions (Iter)) then 590 return; 591 end if; 592 593 -- Capture WHILE condition 594 595 Expression := Condition (Iter); 596 597 -- For iteration, do not process, since loop will always terminate 598 599 elsif Present (Loop_Parameter_Specification (Iter)) then 600 return; 601 end if; 602 end if; 603 end; 604 605 -- Check chain of EXIT statements, we only process loops that have a 606 -- single exit condition (either a single EXIT WHEN statement, or a 607 -- WHILE loop not containing any EXIT WHEN statements). 608 609 declare 610 Ident : constant Node_Id := Identifier (Loop_Statement); 611 Exit_Stmt : Node_Id; 612 613 begin 614 -- If we don't have a proper chain set, ignore call entirely. This 615 -- happens because of previous errors. 616 617 if No (Entity (Ident)) 618 or else Ekind (Entity (Ident)) /= E_Loop 619 then 620 Check_Error_Detected; 621 return; 622 end if; 623 624 -- Otherwise prepare to scan list of EXIT statements 625 626 Exit_Stmt := First_Exit_Statement (Entity (Ident)); 627 while Present (Exit_Stmt) loop 628 629 -- Check for EXIT WHEN 630 631 if Present (Condition (Exit_Stmt)) then 632 633 -- Quit processing if EXIT WHEN in WHILE loop, or more than 634 -- one EXIT WHEN statement present in the loop. 635 636 if Present (Expression) then 637 return; 638 639 -- Otherwise capture condition from EXIT WHEN statement 640 641 else 642 Expression := Condition (Exit_Stmt); 643 end if; 644 645 -- If an unconditional exit statement is the last statement in the 646 -- loop, assume that no warning is needed, without any attempt at 647 -- checking whether the exit is reachable. 648 649 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then 650 return; 651 end if; 652 653 Exit_Stmt := Next_Exit_Statement (Exit_Stmt); 654 end loop; 655 end; 656 657 -- Return if no condition to test 658 659 if No (Expression) then 660 return; 661 end if; 662 663 -- Initial conditions met, see if condition is of right form 664 665 Find_Var (Expression); 666 667 -- Nothing to do if local variable from source not found. If it's a 668 -- renaming, it is probably renaming something too complicated to deal 669 -- with here. 670 671 if No (Var) 672 or else Ekind (Var) /= E_Variable 673 or else Is_Library_Level_Entity (Var) 674 or else not Comes_From_Source (Var) 675 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration 676 then 677 return; 678 679 -- Nothing to do if there is some indirection involved (assume that the 680 -- designated variable might be modified in some way we don't see). 681 -- However, if no function call was found, then we don't care about 682 -- indirections, because the condition must be something like "while X 683 -- /= null loop", so we don't care if X.all is modified in the loop. 684 685 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then 686 return; 687 688 -- Same sort of thing for volatile variable, might be modified by 689 -- some other task or by the operating system in some way. 690 691 elsif Is_Volatile (Var) then 692 return; 693 end if; 694 695 -- Filter out case of original statement sequence starting with delay. 696 -- We assume this is a multi-tasking program and that the condition 697 -- is affected by other threads (some kind of busy wait). 698 699 declare 700 Fstm : constant Node_Id := 701 Original_Node (First (Statements (Loop_Statement))); 702 begin 703 if Nkind (Fstm) = N_Delay_Relative_Statement 704 or else Nkind (Fstm) = N_Delay_Until_Statement 705 then 706 return; 707 end if; 708 end; 709 710 -- We have a variable reference of the right form, now we scan the loop 711 -- body to see if it looks like it might not be modified 712 713 if No_Ref_Found (Loop_Statement) = OK then 714 Error_Msg_NE 715 ("??variable& is not modified in loop body!", Ref, Var); 716 Error_Msg_N 717 ("\??possible infinite loop!", Ref); 718 end if; 719 end Check_Infinite_Loop_Warning; 720 721 ---------------------------- 722 -- Check_Low_Bound_Tested -- 723 ---------------------------- 724 725 procedure Check_Low_Bound_Tested (Expr : Node_Id) is 726 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id); 727 -- Determine whether operand Opnd denotes attribute 'First whose prefix 728 -- is a formal parameter. If this is the case, mark the entity of the 729 -- prefix as having its low bound tested. 730 731 -------------------------------- 732 -- Check_Low_Bound_Tested_For -- 733 -------------------------------- 734 735 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id) is 736 begin 737 if Nkind (Opnd) = N_Attribute_Reference 738 and then Attribute_Name (Opnd) = Name_First 739 and then Is_Entity_Name (Prefix (Opnd)) 740 and then Present (Entity (Prefix (Opnd))) 741 and then Is_Formal (Entity (Prefix (Opnd))) 742 then 743 Set_Low_Bound_Tested (Entity (Prefix (Opnd))); 744 end if; 745 end Check_Low_Bound_Tested_For; 746 747 -- Start of processing for Check_Low_Bound_Tested 748 749 begin 750 if Comes_From_Source (Expr) then 751 Check_Low_Bound_Tested_For (Left_Opnd (Expr)); 752 Check_Low_Bound_Tested_For (Right_Opnd (Expr)); 753 end if; 754 end Check_Low_Bound_Tested; 755 756 ---------------------- 757 -- Check_References -- 758 ---------------------- 759 760 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is 761 E1 : Entity_Id; 762 E1T : Entity_Id; 763 UR : Node_Id; 764 765 function Body_Formal 766 (E : Entity_Id; 767 Accept_Statement : Node_Id) return Entity_Id; 768 -- For an entry formal entity from an entry declaration, find the 769 -- corresponding body formal from the given accept statement. 770 771 procedure May_Need_Initialized_Actual (Ent : Entity_Id); 772 -- If an entity of a generic type has default initialization, then the 773 -- corresponding actual type should be fully initialized, or else there 774 -- will be uninitialized components in the instantiation, that might go 775 -- unreported. This routine marks the type of the uninitialized variable 776 -- appropriately to allow the compiler to emit an appropriate warning 777 -- in the instance. In a sense, the use of a type that requires full 778 -- initialization is a weak part of the generic contract. 779 780 function Missing_Subunits return Boolean; 781 -- We suppress warnings when there are missing subunits, because this 782 -- may generate too many false positives: entities in a parent may only 783 -- be referenced in one of the subunits. We make an exception for 784 -- subunits that contain no other stubs. 785 786 procedure Output_Reference_Error (M : String); 787 -- Used to output an error message. Deals with posting the error on the 788 -- body formal in the accept case. 789 790 function Publicly_Referenceable (Ent : Entity_Id) return Boolean; 791 -- This is true if the entity in question is potentially referenceable 792 -- from another unit. This is true for entities in packages that are at 793 -- the library level. 794 795 function Warnings_Off_E1 return Boolean; 796 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T), 797 -- or for the base type of E1T. 798 799 ----------------- 800 -- Body_Formal -- 801 ----------------- 802 803 function Body_Formal 804 (E : Entity_Id; 805 Accept_Statement : Node_Id) return Entity_Id 806 is 807 Body_Param : Node_Id; 808 Body_E : Entity_Id; 809 810 begin 811 -- Loop to find matching parameter in accept statement 812 813 Body_Param := First (Parameter_Specifications (Accept_Statement)); 814 while Present (Body_Param) loop 815 Body_E := Defining_Identifier (Body_Param); 816 817 if Chars (Body_E) = Chars (E) then 818 return Body_E; 819 end if; 820 821 Next (Body_Param); 822 end loop; 823 824 -- Should never fall through, should always find a match 825 826 raise Program_Error; 827 end Body_Formal; 828 829 --------------------------------- 830 -- May_Need_Initialized_Actual -- 831 --------------------------------- 832 833 procedure May_Need_Initialized_Actual (Ent : Entity_Id) is 834 T : constant Entity_Id := Etype (Ent); 835 Par : constant Node_Id := Parent (T); 836 837 begin 838 if not Is_Generic_Type (T) then 839 null; 840 841 elsif (Nkind (Par)) = N_Private_Extension_Declaration then 842 843 -- We only indicate the first such variable in the generic. 844 845 if No (Uninitialized_Variable (Par)) then 846 Set_Uninitialized_Variable (Par, Ent); 847 end if; 848 849 elsif (Nkind (Par)) = N_Formal_Type_Declaration 850 and then Nkind (Formal_Type_Definition (Par)) = 851 N_Formal_Private_Type_Definition 852 then 853 if No (Uninitialized_Variable (Formal_Type_Definition (Par))) then 854 Set_Uninitialized_Variable (Formal_Type_Definition (Par), Ent); 855 end if; 856 end if; 857 end May_Need_Initialized_Actual; 858 859 ---------------------- 860 -- Missing_Subunits -- 861 ---------------------- 862 863 function Missing_Subunits return Boolean is 864 D : Node_Id; 865 866 begin 867 if not Unloaded_Subunits then 868 869 -- Normal compilation, all subunits are present 870 871 return False; 872 873 elsif E /= Main_Unit_Entity then 874 875 -- No warnings on a stub that is not the main unit 876 877 return True; 878 879 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then 880 D := First (Declarations (Unit_Declaration_Node (E))); 881 while Present (D) loop 882 883 -- No warnings if the proper body contains nested stubs 884 885 if Nkind (D) in N_Body_Stub then 886 return True; 887 end if; 888 889 Next (D); 890 end loop; 891 892 return False; 893 894 else 895 -- Missing stubs elsewhere 896 897 return True; 898 end if; 899 end Missing_Subunits; 900 901 ---------------------------- 902 -- Output_Reference_Error -- 903 ---------------------------- 904 905 procedure Output_Reference_Error (M : String) is 906 begin 907 -- Never issue messages for internal names or renamings 908 909 if Is_Internal_Name (Chars (E1)) 910 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration 911 then 912 return; 913 end if; 914 915 -- Don't output message for IN OUT formal unless we have the warning 916 -- flag specifically set. It is a bit odd to distinguish IN OUT 917 -- formals from other cases. This distinction is historical in 918 -- nature. Warnings for IN OUT formals were added fairly late. 919 920 if Ekind (E1) = E_In_Out_Parameter 921 and then not Check_Unreferenced_Formals 922 then 923 return; 924 end if; 925 926 -- Other than accept case, post error on defining identifier 927 928 if No (Anod) then 929 Error_Msg_N (M, E1); 930 931 -- Accept case, find body formal to post the message 932 933 else 934 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1); 935 936 end if; 937 end Output_Reference_Error; 938 939 ---------------------------- 940 -- Publicly_Referenceable -- 941 ---------------------------- 942 943 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is 944 P : Node_Id; 945 Prev : Node_Id; 946 947 begin 948 -- A formal parameter is never referenceable outside the body of its 949 -- subprogram or entry. 950 951 if Is_Formal (Ent) then 952 return False; 953 end if; 954 955 -- Examine parents to look for a library level package spec. But if 956 -- we find a body or block or other similar construct along the way, 957 -- we cannot be referenced. 958 959 Prev := Ent; 960 P := Parent (Ent); 961 loop 962 case Nkind (P) is 963 964 -- If we get to top of tree, then publicly referenceable 965 966 when N_Empty => 967 return True; 968 969 -- If we reach a generic package declaration, then always 970 -- consider this referenceable, since any instantiation will 971 -- have access to the entities in the generic package. Note 972 -- that the package itself may not be instantiated, but then 973 -- we will get a warning for the package entity. 974 975 -- Note that generic formal parameters are themselves not 976 -- publicly referenceable in an instance, and warnings on them 977 -- are useful. 978 979 when N_Generic_Package_Declaration => 980 return 981 not Is_List_Member (Prev) 982 or else List_Containing (Prev) /= 983 Generic_Formal_Declarations (P); 984 985 -- Similarly, the generic formals of a generic subprogram are 986 -- not accessible. 987 988 when N_Generic_Subprogram_Declaration => 989 if Is_List_Member (Prev) 990 and then List_Containing (Prev) = 991 Generic_Formal_Declarations (P) 992 then 993 return False; 994 else 995 P := Parent (P); 996 end if; 997 998 -- If we reach a subprogram body, entity is not referenceable 999 -- unless it is the defining entity of the body. This will 1000 -- happen, e.g. when a function is an attribute renaming that 1001 -- is rewritten as a body. 1002 1003 when N_Subprogram_Body => 1004 if Ent /= Defining_Entity (P) then 1005 return False; 1006 else 1007 P := Parent (P); 1008 end if; 1009 1010 -- If we reach any other body, definitely not referenceable 1011 1012 when N_Package_Body | 1013 N_Task_Body | 1014 N_Entry_Body | 1015 N_Protected_Body | 1016 N_Block_Statement | 1017 N_Subunit => 1018 return False; 1019 1020 -- For all other cases, keep looking up tree 1021 1022 when others => 1023 Prev := P; 1024 P := Parent (P); 1025 end case; 1026 end loop; 1027 end Publicly_Referenceable; 1028 1029 --------------------- 1030 -- Warnings_Off_E1 -- 1031 --------------------- 1032 1033 function Warnings_Off_E1 return Boolean is 1034 begin 1035 return Has_Warnings_Off (E1T) 1036 or else Has_Warnings_Off (Base_Type (E1T)) 1037 or else Warnings_Off_Check_Spec (E1); 1038 end Warnings_Off_E1; 1039 1040 -- Start of processing for Check_References 1041 1042 begin 1043 Process_Deferred_References; 1044 1045 -- No messages if warnings are suppressed, or if we have detected any 1046 -- real errors so far (this last check avoids junk messages resulting 1047 -- from errors, e.g. a subunit that is not loaded). 1048 1049 if Warning_Mode = Suppress or else Serious_Errors_Detected /= 0 then 1050 return; 1051 end if; 1052 1053 -- We also skip the messages if any subunits were not loaded (see 1054 -- comment in Sem_Ch10 to understand how this is set, and why it is 1055 -- necessary to suppress the warnings in this case). 1056 1057 if Missing_Subunits then 1058 return; 1059 end if; 1060 1061 -- Otherwise loop through entities, looking for suspicious stuff 1062 1063 E1 := First_Entity (E); 1064 while Present (E1) loop 1065 E1T := Etype (E1); 1066 1067 -- We are only interested in source entities. We also don't issue 1068 -- warnings within instances, since the proper place for such 1069 -- warnings is on the template when it is compiled, and we don't 1070 -- issue warnings for variables with names like Junk, Discard etc. 1071 1072 if Comes_From_Source (E1) 1073 and then Instantiation_Location (Sloc (E1)) = No_Location 1074 then 1075 -- We are interested in variables and out/in-out parameters, but 1076 -- we exclude protected types, too complicated to worry about. 1077 1078 if Ekind (E1) = E_Variable 1079 or else 1080 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter) 1081 and then not Is_Protected_Type (Current_Scope)) 1082 then 1083 -- If the formal has a class-wide type, retrieve its type 1084 -- because checks below depend on its private nature. 1085 1086 if Is_Class_Wide_Type (E1T) then 1087 E1T := Etype (E1T); 1088 end if; 1089 1090 -- Case of an unassigned variable 1091 1092 -- First gather any Unset_Reference indication for E1. In the 1093 -- case of a parameter, it is the Spec_Entity that is relevant. 1094 1095 if Ekind (E1) = E_Out_Parameter 1096 and then Present (Spec_Entity (E1)) 1097 then 1098 UR := Unset_Reference (Spec_Entity (E1)); 1099 else 1100 UR := Unset_Reference (E1); 1101 end if; 1102 1103 -- Special processing for access types 1104 1105 if Present (UR) and then Is_Access_Type (E1T) then 1106 1107 -- For access types, the only time we made a UR entry was 1108 -- for a dereference, and so we post the appropriate warning 1109 -- here (note that the dereference may not be explicit in 1110 -- the source, for example in the case of a dispatching call 1111 -- with an anonymous access controlling formal, or of an 1112 -- assignment of a pointer involving discriminant check on 1113 -- the designated object). 1114 1115 if not Warnings_Off_E1 then 1116 Error_Msg_NE ("??& may be null!", UR, E1); 1117 end if; 1118 1119 goto Continue; 1120 1121 -- Case of variable that could be a constant. Note that we 1122 -- never signal such messages for generic package entities, 1123 -- since a given instance could have modifications outside 1124 -- the package. 1125 1126 -- Note that we used to check Address_Taken here, but we don't 1127 -- want to do that since it can be set for non-source cases, 1128 -- e.g. the Unrestricted_Access from a valid attribute, and 1129 -- the wanted effect is included in Never_Set_In_Source. 1130 1131 elsif Warn_On_Constant 1132 and then (Ekind (E1) = E_Variable 1133 and then Has_Initial_Value (E1)) 1134 and then Never_Set_In_Source_Check_Spec (E1) 1135 and then not Generic_Package_Spec_Entity (E1) 1136 then 1137 -- A special case, if this variable is volatile and not 1138 -- imported, it is not helpful to tell the programmer 1139 -- to mark the variable as constant, since this would be 1140 -- illegal by virtue of RM C.6(13). 1141 1142 if (Is_Volatile (E1) or else Has_Volatile_Components (E1)) 1143 and then not Is_Imported (E1) 1144 then 1145 Error_Msg_N 1146 ("?k?& is not modified, volatile has no effect!", E1); 1147 1148 -- Another special case, Exception_Occurrence, this catches 1149 -- the case of exception choice (and a bit more too, but not 1150 -- worth doing more investigation here). 1151 1152 elsif Is_RTE (E1T, RE_Exception_Occurrence) then 1153 null; 1154 1155 -- Here we give the warning if referenced and no pragma 1156 -- Unreferenced or Unmodified is present. 1157 1158 else 1159 -- Variable case 1160 1161 if Ekind (E1) = E_Variable then 1162 if Referenced_Check_Spec (E1) 1163 and then not Has_Pragma_Unreferenced_Check_Spec (E1) 1164 and then not Has_Pragma_Unmodified_Check_Spec (E1) 1165 then 1166 if not Warnings_Off_E1 1167 and then not Has_Junk_Name (E1) 1168 then 1169 Error_Msg_N -- CODEFIX 1170 ("?k?& is not modified, " 1171 & "could be declared constant!", 1172 E1); 1173 end if; 1174 end if; 1175 end if; 1176 end if; 1177 1178 -- Other cases of a variable or parameter never set in source 1179 1180 elsif Never_Set_In_Source_Check_Spec (E1) 1181 1182 -- No warning if warning for this case turned off 1183 1184 and then Warn_On_No_Value_Assigned 1185 1186 -- No warning if address taken somewhere 1187 1188 and then not Address_Taken (E1) 1189 1190 -- No warning if explicit initial value 1191 1192 and then not Has_Initial_Value (E1) 1193 1194 -- No warning for generic package spec entities, since we 1195 -- might set them in a child unit or something like that 1196 1197 and then not Generic_Package_Spec_Entity (E1) 1198 1199 -- No warning if fully initialized type, except that for 1200 -- this purpose we do not consider access types to qualify 1201 -- as fully initialized types (relying on an access type 1202 -- variable being null when it is never set is a bit odd). 1203 1204 -- Also we generate warning for an out parameter that is 1205 -- never referenced, since again it seems odd to rely on 1206 -- default initialization to set an out parameter value. 1207 1208 and then (Is_Access_Type (E1T) 1209 or else Ekind (E1) = E_Out_Parameter 1210 or else not Is_Fully_Initialized_Type (E1T)) 1211 then 1212 -- Do not output complaint about never being assigned a 1213 -- value if a pragma Unmodified applies to the variable 1214 -- we are examining, or if it is a parameter, if there is 1215 -- a pragma Unreferenced for the corresponding spec, or 1216 -- if the type is marked as having unreferenced objects. 1217 -- The last is a little peculiar, but better too few than 1218 -- too many warnings in this situation. 1219 1220 if Has_Pragma_Unreferenced_Objects (E1T) 1221 or else Has_Pragma_Unmodified_Check_Spec (E1) 1222 then 1223 null; 1224 1225 -- IN OUT parameter case where parameter is referenced. We 1226 -- separate this out, since this is the case where we delay 1227 -- output of the warning until more information is available 1228 -- (about use in an instantiation or address being taken). 1229 1230 elsif Ekind (E1) = E_In_Out_Parameter 1231 and then Referenced_Check_Spec (E1) 1232 then 1233 -- Suppress warning if private type, and the procedure 1234 -- has a separate declaration in a different unit. This 1235 -- is the case where the client of a package sees only 1236 -- the private type, and it may be quite reasonable 1237 -- for the logical view to be IN OUT, even if the 1238 -- implementation ends up using access types or some 1239 -- other method to achieve the local effect of a 1240 -- modification. On the other hand if the spec and body 1241 -- are in the same unit, we are in the package body and 1242 -- there we have less excuse for a junk IN OUT parameter. 1243 1244 if Has_Private_Declaration (E1T) 1245 and then Present (Spec_Entity (E1)) 1246 and then not In_Same_Source_Unit (E1, Spec_Entity (E1)) 1247 then 1248 null; 1249 1250 -- Suppress warning for any parameter of a dispatching 1251 -- operation, since it is quite reasonable to have an 1252 -- operation that is overridden, and for some subclasses 1253 -- needs the formal to be IN OUT and for others happens 1254 -- not to assign it. 1255 1256 elsif Is_Dispatching_Operation 1257 (Scope (Goto_Spec_Entity (E1))) 1258 then 1259 null; 1260 1261 -- Suppress warning if composite type contains any access 1262 -- component, since the logical effect of modifying a 1263 -- parameter may be achieved by modifying a referenced 1264 -- object. 1265 1266 elsif Is_Composite_Type (E1T) 1267 and then Has_Access_Values (E1T) 1268 then 1269 null; 1270 1271 -- Suppress warning on formals of an entry body. All 1272 -- references are attached to the formal in the entry 1273 -- declaration, which are marked Is_Entry_Formal. 1274 1275 elsif Ekind (Scope (E1)) = E_Entry 1276 and then not Is_Entry_Formal (E1) 1277 then 1278 null; 1279 1280 -- OK, looks like warning for an IN OUT parameter that 1281 -- could be IN makes sense, but we delay the output of 1282 -- the warning, pending possibly finding out later on 1283 -- that the associated subprogram is used as a generic 1284 -- actual, or its address/access is taken. In these two 1285 -- cases, we suppress the warning because the context may 1286 -- force use of IN OUT, even if in this particular case 1287 -- the formal is not modified. 1288 1289 else 1290 -- Suppress the warnings for a junk name 1291 1292 if not Has_Junk_Name (E1) then 1293 In_Out_Warnings.Append (E1); 1294 end if; 1295 end if; 1296 1297 -- Other cases of formals 1298 1299 elsif Is_Formal (E1) then 1300 if not Is_Trivial_Subprogram (Scope (E1)) then 1301 if Referenced_Check_Spec (E1) then 1302 if not Has_Pragma_Unmodified_Check_Spec (E1) 1303 and then not Warnings_Off_E1 1304 and then not Has_Junk_Name (E1) 1305 then 1306 Output_Reference_Error 1307 ("?f?formal parameter& is read but " 1308 & "never assigned!"); 1309 end if; 1310 1311 elsif not Has_Pragma_Unreferenced_Check_Spec (E1) 1312 and then not Warnings_Off_E1 1313 and then not Has_Junk_Name (E1) 1314 then 1315 Output_Reference_Error 1316 ("?f?formal parameter& is not referenced!"); 1317 end if; 1318 end if; 1319 1320 -- Case of variable 1321 1322 else 1323 if Referenced (E1) then 1324 if not Has_Unmodified (E1) 1325 and then not Warnings_Off_E1 1326 and then not Has_Junk_Name (E1) 1327 then 1328 Output_Reference_Error 1329 ("?v?variable& is read but never assigned!"); 1330 May_Need_Initialized_Actual (E1); 1331 end if; 1332 1333 elsif not Has_Unreferenced (E1) 1334 and then not Warnings_Off_E1 1335 and then not Has_Junk_Name (E1) 1336 then 1337 Output_Reference_Error -- CODEFIX 1338 ("?v?variable& is never read and never assigned!"); 1339 end if; 1340 1341 -- Deal with special case where this variable is hidden 1342 -- by a loop variable. 1343 1344 if Ekind (E1) = E_Variable 1345 and then Present (Hiding_Loop_Variable (E1)) 1346 and then not Warnings_Off_E1 1347 then 1348 Error_Msg_N 1349 ("?v?for loop implicitly declares loop variable!", 1350 Hiding_Loop_Variable (E1)); 1351 1352 Error_Msg_Sloc := Sloc (E1); 1353 Error_Msg_N 1354 ("\?v?declaration hides & declared#!", 1355 Hiding_Loop_Variable (E1)); 1356 end if; 1357 end if; 1358 1359 goto Continue; 1360 end if; 1361 1362 -- Check for unset reference 1363 1364 if Warn_On_No_Value_Assigned and then Present (UR) then 1365 1366 -- For other than access type, go back to original node to 1367 -- deal with case where original unset reference has been 1368 -- rewritten during expansion. 1369 1370 -- In some cases, the original node may be a type conversion 1371 -- or qualification, and in this case we want the object 1372 -- entity inside. 1373 1374 UR := Original_Node (UR); 1375 while Nkind (UR) = N_Type_Conversion 1376 or else Nkind (UR) = N_Qualified_Expression 1377 or else Nkind (UR) = N_Expression_With_Actions 1378 loop 1379 UR := Expression (UR); 1380 end loop; 1381 1382 -- Don't issue warning if appearing inside Initial_Condition 1383 -- pragma or aspect, since that expression is not evaluated 1384 -- at the point where it occurs in the source. 1385 1386 if In_Pragma_Expression (UR, Name_Initial_Condition) then 1387 goto Continue; 1388 end if; 1389 1390 -- Here we issue the warning, all checks completed 1391 1392 -- If we have a return statement, this was a case of an OUT 1393 -- parameter not being set at the time of the return. (Note: 1394 -- it can't be N_Extended_Return_Statement, because those 1395 -- are only for functions, and functions do not allow OUT 1396 -- parameters.) 1397 1398 if not Is_Trivial_Subprogram (Scope (E1)) then 1399 if Nkind (UR) = N_Simple_Return_Statement 1400 and then not Has_Pragma_Unmodified_Check_Spec (E1) 1401 then 1402 if not Warnings_Off_E1 1403 and then not Has_Junk_Name (E1) 1404 then 1405 Error_Msg_NE 1406 ("?v?OUT parameter& not set before return", 1407 UR, E1); 1408 end if; 1409 1410 -- If the unset reference is a selected component 1411 -- prefix from source, mention the component as well. 1412 -- If the selected component comes from expansion, all 1413 -- we know is that the entity is not fully initialized 1414 -- at the point of the reference. Locate a random 1415 -- uninitialized component to get a better message. 1416 1417 elsif Nkind (Parent (UR)) = N_Selected_Component then 1418 Error_Msg_Node_2 := Selector_Name (Parent (UR)); 1419 1420 if not Comes_From_Source (Parent (UR)) then 1421 declare 1422 Comp : Entity_Id; 1423 1424 begin 1425 Comp := First_Entity (E1T); 1426 while Present (Comp) loop 1427 if Ekind (Comp) = E_Component 1428 and then Nkind (Parent (Comp)) = 1429 N_Component_Declaration 1430 and then No (Expression (Parent (Comp))) 1431 then 1432 Error_Msg_Node_2 := Comp; 1433 exit; 1434 end if; 1435 1436 Next_Entity (Comp); 1437 end loop; 1438 end; 1439 end if; 1440 1441 -- Issue proper warning. This is a case of referencing 1442 -- a variable before it has been explicitly assigned. 1443 -- For access types, UR was only set for dereferences, 1444 -- so the issue is that the value may be null. 1445 1446 if not Is_Trivial_Subprogram (Scope (E1)) then 1447 if not Warnings_Off_E1 then 1448 if Is_Access_Type (Etype (Parent (UR))) then 1449 Error_Msg_N ("??`&.&` may be null!", UR); 1450 else 1451 Error_Msg_N 1452 ("??`&.&` may be referenced before " 1453 & "it has a value!", UR); 1454 end if; 1455 end if; 1456 end if; 1457 1458 -- All other cases of unset reference active 1459 1460 elsif not Warnings_Off_E1 then 1461 Error_Msg_N 1462 ("??& may be referenced before it has a value!", UR); 1463 end if; 1464 end if; 1465 1466 goto Continue; 1467 1468 end if; 1469 end if; 1470 1471 -- Then check for unreferenced entities. Note that we are only 1472 -- interested in entities whose Referenced flag is not set. 1473 1474 if not Referenced_Check_Spec (E1) 1475 1476 -- If Referenced_As_LHS is set, then that's still interesting 1477 -- (potential "assigned but never read" case), but not if we 1478 -- have pragma Unreferenced, which cancels this warning. 1479 1480 and then (not Referenced_As_LHS_Check_Spec (E1) 1481 or else not Has_Unreferenced (E1)) 1482 1483 -- Check that warnings on unreferenced entities are enabled 1484 1485 and then 1486 ((Check_Unreferenced and then not Is_Formal (E1)) 1487 1488 -- Case of warning on unreferenced formal 1489 1490 or else (Check_Unreferenced_Formals and then Is_Formal (E1)) 1491 1492 -- Case of warning on unread variables modified by an 1493 -- assignment, or an OUT parameter if it is the only one. 1494 1495 or else (Warn_On_Modified_Unread 1496 and then Referenced_As_LHS_Check_Spec (E1)) 1497 1498 -- Case of warning on any unread OUT parameter (note such 1499 -- indications are only set if the appropriate warning 1500 -- options were set, so no need to recheck here.) 1501 1502 or else Referenced_As_Out_Parameter_Check_Spec (E1)) 1503 1504 -- All other entities, including local packages that cannot be 1505 -- referenced from elsewhere, including those declared within a 1506 -- package body. 1507 1508 and then (Is_Object (E1) 1509 or else Is_Type (E1) 1510 or else Ekind (E1) = E_Label 1511 or else Ekind_In (E1, E_Exception, 1512 E_Named_Integer, 1513 E_Named_Real) 1514 or else Is_Overloadable (E1) 1515 1516 -- Package case, if the main unit is a package spec 1517 -- or generic package spec, then there may be a 1518 -- corresponding body that references this package 1519 -- in some other file. Otherwise we can be sure 1520 -- that there is no other reference. 1521 1522 or else 1523 (Ekind (E1) = E_Package 1524 and then 1525 not Is_Package_Or_Generic_Package 1526 (Cunit_Entity (Current_Sem_Unit)))) 1527 1528 -- Exclude instantiations, since there is no reason why every 1529 -- entity in an instantiation should be referenced. 1530 1531 and then Instantiation_Location (Sloc (E1)) = No_Location 1532 1533 -- Exclude formal parameters from bodies if the corresponding 1534 -- spec entity has been referenced in the case where there is 1535 -- a separate spec. 1536 1537 and then not (Is_Formal (E1) 1538 and then Ekind (Scope (E1)) = E_Subprogram_Body 1539 and then Present (Spec_Entity (E1)) 1540 and then Referenced (Spec_Entity (E1))) 1541 1542 -- Consider private type referenced if full view is referenced. 1543 -- If there is not full view, this is a generic type on which 1544 -- warnings are also useful. 1545 1546 and then 1547 not (Is_Private_Type (E1) 1548 and then Present (Full_View (E1)) 1549 and then Referenced (Full_View (E1))) 1550 1551 -- Don't worry about full view, only about private type 1552 1553 and then not Has_Private_Declaration (E1) 1554 1555 -- Eliminate dispatching operations from consideration, we 1556 -- cannot tell if these are referenced or not in any easy 1557 -- manner (note this also catches Adjust/Finalize/Initialize). 1558 1559 and then not Is_Dispatching_Operation (E1) 1560 1561 -- Check entity that can be publicly referenced (we do not give 1562 -- messages for such entities, since there could be other 1563 -- units, not involved in this compilation, that contain 1564 -- relevant references. 1565 1566 and then not Publicly_Referenceable (E1) 1567 1568 -- Class wide types are marked as source entities, but they are 1569 -- not really source entities, and are always created, so we do 1570 -- not care if they are not referenced. 1571 1572 and then Ekind (E1) /= E_Class_Wide_Type 1573 1574 -- Objects other than parameters of task types are allowed to 1575 -- be non-referenced, since they start up tasks. 1576 1577 and then ((Ekind (E1) /= E_Variable 1578 and then Ekind (E1) /= E_Constant 1579 and then Ekind (E1) /= E_Component) 1580 or else not Is_Task_Type (E1T)) 1581 1582 -- For subunits, only place warnings on the main unit itself, 1583 -- since parent units are not completely compiled. 1584 1585 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit 1586 or else Get_Source_Unit (E1) = Main_Unit) 1587 1588 -- No warning on a return object, because these are often 1589 -- created with a single expression and an implicit return. 1590 -- If the object is a variable there will be a warning 1591 -- indicating that it could be declared constant. 1592 1593 and then not 1594 (Ekind (E1) = E_Constant and then Is_Return_Object (E1)) 1595 then 1596 -- Suppress warnings in internal units if not in -gnatg mode 1597 -- (these would be junk warnings for an applications program, 1598 -- since they refer to problems in internal units). 1599 1600 if GNAT_Mode 1601 or else not Is_Internal_File_Name 1602 (Unit_File_Name (Get_Source_Unit (E1))) 1603 then 1604 -- We do not immediately flag the error. This is because we 1605 -- have not expanded generic bodies yet, and they may have 1606 -- the missing reference. So instead we park the entity on a 1607 -- list, for later processing. However for the case of an 1608 -- accept statement we want to output messages now, since 1609 -- we know we already have all information at hand, and we 1610 -- also want to have separate warnings for each accept 1611 -- statement for the same entry. 1612 1613 if Present (Anod) then 1614 pragma Assert (Is_Formal (E1)); 1615 1616 -- The unreferenced entity is E1, but post the warning 1617 -- on the body entity for this accept statement. 1618 1619 if not Warnings_Off_E1 then 1620 Warn_On_Unreferenced_Entity 1621 (E1, Body_Formal (E1, Accept_Statement => Anod)); 1622 end if; 1623 1624 elsif not Warnings_Off_E1 1625 and then not Has_Junk_Name (E1) 1626 then 1627 Unreferenced_Entities.Append (E1); 1628 end if; 1629 end if; 1630 1631 -- Generic units are referenced in the generic body, but if they 1632 -- are not public and never instantiated we want to force a 1633 -- warning on them. We treat them as redundant constructs to 1634 -- minimize noise. 1635 1636 elsif Is_Generic_Subprogram (E1) 1637 and then not Is_Instantiated (E1) 1638 and then not Publicly_Referenceable (E1) 1639 and then Instantiation_Depth (Sloc (E1)) = 0 1640 and then Warn_On_Redundant_Constructs 1641 then 1642 if not Warnings_Off_E1 and then not Has_Junk_Name (E1) then 1643 Unreferenced_Entities.Append (E1); 1644 1645 -- Force warning on entity 1646 1647 Set_Referenced (E1, False); 1648 end if; 1649 end if; 1650 end if; 1651 1652 -- Recurse into nested package or block. Do not recurse into a formal 1653 -- package, because the corresponding body is not analyzed. 1654 1655 <<Continue>> 1656 if (Is_Package_Or_Generic_Package (E1) 1657 and then Nkind (Parent (E1)) = N_Package_Specification 1658 and then 1659 Nkind (Original_Node (Unit_Declaration_Node (E1))) /= 1660 N_Formal_Package_Declaration) 1661 1662 or else Ekind (E1) = E_Block 1663 then 1664 Check_References (E1); 1665 end if; 1666 1667 Next_Entity (E1); 1668 end loop; 1669 end Check_References; 1670 1671 --------------------------- 1672 -- Check_Unset_Reference -- 1673 --------------------------- 1674 1675 procedure Check_Unset_Reference (N : Node_Id) is 1676 Typ : constant Entity_Id := Etype (N); 1677 1678 function Is_OK_Fully_Initialized return Boolean; 1679 -- This function returns true if the given node N is fully initialized 1680 -- so that the reference is safe as far as this routine is concerned. 1681 -- Safe generally means that the type of N is a fully initialized type. 1682 -- The one special case is that for access types, which are always fully 1683 -- initialized, we don't consider a dereference OK since it will surely 1684 -- be dereferencing a null value, which won't do. 1685 1686 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean; 1687 -- Used to test indexed or selected component or slice to see if the 1688 -- evaluation of the prefix depends on a dereference, and if so, returns 1689 -- True, in which case we always check the prefix, even if we know that 1690 -- the referenced component is initialized. Pref is the prefix to test. 1691 1692 ----------------------------- 1693 -- Is_OK_Fully_Initialized -- 1694 ----------------------------- 1695 1696 function Is_OK_Fully_Initialized return Boolean is 1697 begin 1698 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then 1699 return False; 1700 else 1701 return Is_Fully_Initialized_Type (Typ); 1702 end if; 1703 end Is_OK_Fully_Initialized; 1704 1705 ---------------------------- 1706 -- Prefix_Has_Dereference -- 1707 ---------------------------- 1708 1709 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is 1710 begin 1711 -- If prefix is of an access type, it certainly needs a dereference 1712 1713 if Is_Access_Type (Etype (Pref)) then 1714 return True; 1715 1716 -- If prefix is explicit dereference, that's a dereference for sure 1717 1718 elsif Nkind (Pref) = N_Explicit_Dereference then 1719 return True; 1720 1721 -- If prefix is itself a component reference or slice check prefix 1722 1723 elsif Nkind (Pref) = N_Slice 1724 or else Nkind (Pref) = N_Indexed_Component 1725 or else Nkind (Pref) = N_Selected_Component 1726 then 1727 return Prefix_Has_Dereference (Prefix (Pref)); 1728 1729 -- All other cases do not involve a dereference 1730 1731 else 1732 return False; 1733 end if; 1734 end Prefix_Has_Dereference; 1735 1736 -- Start of processing for Check_Unset_Reference 1737 1738 begin 1739 -- Nothing to do if warnings suppressed 1740 1741 if Warning_Mode = Suppress then 1742 return; 1743 end if; 1744 1745 -- Nothing to do for numeric or string literal. Do this test early to 1746 -- save time in a common case (it does not matter that we do not include 1747 -- character literal here, since that will be caught later on in the 1748 -- when others branch of the case statement). 1749 1750 if Nkind (N) in N_Numeric_Or_String_Literal then 1751 return; 1752 end if; 1753 1754 -- Ignore reference unless it comes from source. Almost always if we 1755 -- have a reference from generated code, it is bogus (e.g. calls to init 1756 -- procs to set default discriminant values). 1757 1758 if not Comes_From_Source (N) then 1759 return; 1760 end if; 1761 1762 -- Otherwise see what kind of node we have. If the entity already has an 1763 -- unset reference, it is not necessarily the earliest in the text, 1764 -- because resolution of the prefix of selected components is completed 1765 -- before the resolution of the selected component itself. As a result, 1766 -- given (R /= null and then R.X > 0), the occurrences of R are examined 1767 -- in right-to-left order. If there is already an unset reference, we 1768 -- check whether N is earlier before proceeding. 1769 1770 case Nkind (N) is 1771 1772 -- For identifier or expanded name, examine the entity involved 1773 1774 when N_Identifier | N_Expanded_Name => 1775 declare 1776 E : constant Entity_Id := Entity (N); 1777 1778 begin 1779 if Ekind_In (E, E_Variable, E_Out_Parameter) 1780 and then Never_Set_In_Source_Check_Spec (E) 1781 and then not Has_Initial_Value (E) 1782 and then (No (Unset_Reference (E)) 1783 or else 1784 Earlier_In_Extended_Unit 1785 (Sloc (N), Sloc (Unset_Reference (E)))) 1786 and then not Has_Pragma_Unmodified_Check_Spec (E) 1787 and then not Warnings_Off_Check_Spec (E) 1788 and then not Has_Junk_Name (E) 1789 then 1790 -- We may have an unset reference. The first test is whether 1791 -- this is an access to a discriminant of a record or a 1792 -- component with default initialization. Both of these 1793 -- cases can be ignored, since the actual object that is 1794 -- referenced is definitely initialized. Note that this 1795 -- covers the case of reading discriminants of an OUT 1796 -- parameter, which is OK even in Ada 83. 1797 1798 -- Note that we are only interested in a direct reference to 1799 -- a record component here. If the reference is through an 1800 -- access type, then the access object is being referenced, 1801 -- not the record, and still deserves an unset reference. 1802 1803 if Nkind (Parent (N)) = N_Selected_Component 1804 and not Is_Access_Type (Typ) 1805 then 1806 declare 1807 ES : constant Entity_Id := 1808 Entity (Selector_Name (Parent (N))); 1809 begin 1810 if Ekind (ES) = E_Discriminant 1811 or else 1812 (Present (Declaration_Node (ES)) 1813 and then 1814 Present (Expression (Declaration_Node (ES)))) 1815 then 1816 return; 1817 end if; 1818 end; 1819 end if; 1820 1821 -- Exclude fully initialized types 1822 1823 if Is_OK_Fully_Initialized then 1824 return; 1825 end if; 1826 1827 -- Here we have a potential unset reference. But before we 1828 -- get worried about it, we have to make sure that the 1829 -- entity declaration is in the same procedure as the 1830 -- reference, since if they are in separate procedures, then 1831 -- we have no idea about sequential execution. 1832 1833 -- The tests in the loop below catch all such cases, but do 1834 -- allow the reference to appear in a loop, block, or 1835 -- package spec that is nested within the declaring scope. 1836 -- As always, it is possible to construct cases where the 1837 -- warning is wrong, that is why it is a warning. 1838 1839 Potential_Unset_Reference : declare 1840 SR : Entity_Id; 1841 SE : constant Entity_Id := Scope (E); 1842 1843 function Within_Postcondition return Boolean; 1844 -- Returns True if N is within a Postcondition, a 1845 -- Refined_Post, an Ensures component in a Test_Case, 1846 -- or a Contract_Cases. 1847 1848 -------------------------- 1849 -- Within_Postcondition -- 1850 -------------------------- 1851 1852 function Within_Postcondition return Boolean is 1853 Nod, P : Node_Id; 1854 1855 begin 1856 Nod := Parent (N); 1857 while Present (Nod) loop 1858 if Nkind (Nod) = N_Pragma 1859 and then Nam_In (Pragma_Name (Nod), 1860 Name_Postcondition, 1861 Name_Refined_Post, 1862 Name_Contract_Cases) 1863 then 1864 return True; 1865 1866 elsif Present (Parent (Nod)) then 1867 P := Parent (Nod); 1868 1869 if Nkind (P) = N_Pragma 1870 and then Pragma_Name (P) = Name_Test_Case 1871 and then Nod = Test_Case_Arg (P, Name_Ensures) 1872 then 1873 return True; 1874 end if; 1875 end if; 1876 1877 Nod := Parent (Nod); 1878 end loop; 1879 1880 return False; 1881 end Within_Postcondition; 1882 1883 -- Start of processing for Potential_Unset_Reference 1884 1885 begin 1886 SR := Current_Scope; 1887 while SR /= SE loop 1888 if SR = Standard_Standard 1889 or else Is_Subprogram (SR) 1890 or else Is_Concurrent_Body (SR) 1891 or else Is_Concurrent_Type (SR) 1892 then 1893 return; 1894 end if; 1895 1896 SR := Scope (SR); 1897 end loop; 1898 1899 -- Case of reference has an access type. This is a 1900 -- special case since access types are always set to null 1901 -- so cannot be truly uninitialized, but we still want to 1902 -- warn about cases of obvious null dereference. 1903 1904 if Is_Access_Type (Typ) then 1905 Access_Type_Case : declare 1906 P : Node_Id; 1907 1908 function Process 1909 (N : Node_Id) return Traverse_Result; 1910 -- Process function for instantiation of Traverse 1911 -- below. Checks if N contains reference to E other 1912 -- than a dereference. 1913 1914 function Ref_In (Nod : Node_Id) return Boolean; 1915 -- Determines whether Nod contains a reference to 1916 -- the entity E that is not a dereference. 1917 1918 ------------- 1919 -- Process -- 1920 ------------- 1921 1922 function Process 1923 (N : Node_Id) return Traverse_Result 1924 is 1925 begin 1926 if Is_Entity_Name (N) 1927 and then Entity (N) = E 1928 and then not Is_Dereferenced (N) 1929 then 1930 return Abandon; 1931 else 1932 return OK; 1933 end if; 1934 end Process; 1935 1936 ------------ 1937 -- Ref_In -- 1938 ------------ 1939 1940 function Ref_In (Nod : Node_Id) return Boolean is 1941 function Traverse is new Traverse_Func (Process); 1942 begin 1943 return Traverse (Nod) = Abandon; 1944 end Ref_In; 1945 1946 -- Start of processing for Access_Type_Case 1947 1948 begin 1949 -- Don't bother if we are inside an instance, since 1950 -- the compilation of the generic template is where 1951 -- the warning should be issued. 1952 1953 if In_Instance then 1954 return; 1955 end if; 1956 1957 -- Don't bother if this is not the main unit. If we 1958 -- try to give this warning for with'ed units, we 1959 -- get some false positives, since we do not record 1960 -- references in other units. 1961 1962 if not In_Extended_Main_Source_Unit (E) 1963 or else 1964 not In_Extended_Main_Source_Unit (N) 1965 then 1966 return; 1967 end if; 1968 1969 -- We are only interested in dereferences 1970 1971 if not Is_Dereferenced (N) then 1972 return; 1973 end if; 1974 1975 -- One more check, don't bother with references 1976 -- that are inside conditional statements or WHILE 1977 -- loops if the condition references the entity in 1978 -- question. This avoids most false positives. 1979 1980 P := Parent (N); 1981 loop 1982 P := Parent (P); 1983 exit when No (P); 1984 1985 if Nkind_In (P, N_If_Statement, N_Elsif_Part) 1986 and then Ref_In (Condition (P)) 1987 then 1988 return; 1989 1990 elsif Nkind (P) = N_Loop_Statement 1991 and then Present (Iteration_Scheme (P)) 1992 and then 1993 Ref_In (Condition (Iteration_Scheme (P))) 1994 then 1995 return; 1996 end if; 1997 end loop; 1998 end Access_Type_Case; 1999 end if; 2000 2001 -- One more check, don't bother if we are within a 2002 -- postcondition, since the expression occurs in a 2003 -- place unrelated to the actual test. 2004 2005 if not Within_Postcondition then 2006 2007 -- Here we definitely have a case for giving a warning 2008 -- for a reference to an unset value. But we don't 2009 -- give the warning now. Instead set Unset_Reference 2010 -- in the identifier involved. The reason for this is 2011 -- that if we find the variable is never ever assigned 2012 -- a value then that warning is more important and 2013 -- there is no point in giving the reference warning. 2014 2015 -- If this is an identifier, set the field directly 2016 2017 if Nkind (N) = N_Identifier then 2018 Set_Unset_Reference (E, N); 2019 2020 -- Otherwise it is an expanded name, so set the field 2021 -- of the actual identifier for the reference. 2022 2023 else 2024 Set_Unset_Reference (E, Selector_Name (N)); 2025 end if; 2026 end if; 2027 end Potential_Unset_Reference; 2028 end if; 2029 end; 2030 2031 -- Indexed component or slice 2032 2033 when N_Indexed_Component | N_Slice => 2034 2035 -- If prefix does not involve dereferencing an access type, then 2036 -- we know we are OK if the component type is fully initialized, 2037 -- since the component will have been set as part of the default 2038 -- initialization. 2039 2040 if not Prefix_Has_Dereference (Prefix (N)) 2041 and then Is_OK_Fully_Initialized 2042 then 2043 return; 2044 2045 -- Look at prefix in access type case, or if the component is not 2046 -- fully initialized. 2047 2048 else 2049 Check_Unset_Reference (Prefix (N)); 2050 end if; 2051 2052 -- Record component 2053 2054 when N_Selected_Component => 2055 declare 2056 Pref : constant Node_Id := Prefix (N); 2057 Ent : constant Entity_Id := Entity (Selector_Name (N)); 2058 2059 begin 2060 -- If prefix involves dereferencing an access type, always 2061 -- check the prefix, since the issue then is whether this 2062 -- access value is null. 2063 2064 if Prefix_Has_Dereference (Pref) then 2065 null; 2066 2067 -- Always go to prefix if no selector entity is set. Can this 2068 -- happen in the normal case? Not clear, but it definitely can 2069 -- happen in error cases. 2070 2071 elsif No (Ent) then 2072 null; 2073 2074 -- For a record component, check some cases where we have 2075 -- reasonable cause to consider that the component is known to 2076 -- be or probably is initialized. In this case, we don't care 2077 -- if the prefix itself was explicitly initialized. 2078 2079 -- Discriminants are always considered initialized 2080 2081 elsif Ekind (Ent) = E_Discriminant then 2082 return; 2083 2084 -- An explicitly initialized component is certainly initialized 2085 2086 elsif Nkind (Parent (Ent)) = N_Component_Declaration 2087 and then Present (Expression (Parent (Ent))) 2088 then 2089 return; 2090 2091 -- A fully initialized component is initialized 2092 2093 elsif Is_OK_Fully_Initialized then 2094 return; 2095 end if; 2096 2097 -- If none of those cases apply, check the record type prefix 2098 2099 Check_Unset_Reference (Pref); 2100 end; 2101 2102 -- For type conversions, qualifications, or expressions with actions, 2103 -- examine the expression. 2104 2105 when N_Type_Conversion | 2106 N_Qualified_Expression | 2107 N_Expression_With_Actions => 2108 Check_Unset_Reference (Expression (N)); 2109 2110 -- For explicit dereference, always check prefix, which will generate 2111 -- an unset reference (since this is a case of dereferencing null). 2112 2113 when N_Explicit_Dereference => 2114 Check_Unset_Reference (Prefix (N)); 2115 2116 -- All other cases are not cases of an unset reference 2117 2118 when others => 2119 null; 2120 2121 end case; 2122 end Check_Unset_Reference; 2123 2124 ------------------------ 2125 -- Check_Unused_Withs -- 2126 ------------------------ 2127 2128 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is 2129 Cnode : Node_Id; 2130 Item : Node_Id; 2131 Lunit : Node_Id; 2132 Ent : Entity_Id; 2133 2134 Munite : constant Entity_Id := Cunit_Entity (Main_Unit); 2135 -- This is needed for checking the special renaming case 2136 2137 procedure Check_One_Unit (Unit : Unit_Number_Type); 2138 -- Subsidiary procedure, performs checks for specified unit 2139 2140 -------------------- 2141 -- Check_One_Unit -- 2142 -------------------- 2143 2144 procedure Check_One_Unit (Unit : Unit_Number_Type) is 2145 Is_Visible_Renaming : Boolean := False; 2146 Pack : Entity_Id; 2147 2148 procedure Check_Inner_Package (Pack : Entity_Id); 2149 -- Pack is a package local to a unit in a with_clause. Both the unit 2150 -- and Pack are referenced. If none of the entities in Pack are 2151 -- referenced, then the only occurrence of Pack is in a USE clause 2152 -- or a pragma, and a warning is worthwhile as well. 2153 2154 function Check_System_Aux return Boolean; 2155 -- Before giving a warning on a with_clause for System, check whether 2156 -- a system extension is present. 2157 2158 function Find_Package_Renaming 2159 (P : Entity_Id; 2160 L : Entity_Id) return Entity_Id; 2161 -- The only reference to a context unit may be in a renaming 2162 -- declaration. If this renaming declares a visible entity, do not 2163 -- warn that the context clause could be moved to the body, because 2164 -- the renaming may be intended to re-export the unit. 2165 2166 function Has_Visible_Entities (P : Entity_Id) return Boolean; 2167 -- This function determines if a package has any visible entities. 2168 -- True is returned if there is at least one declared visible entity, 2169 -- otherwise False is returned (e.g. case of only pragmas present). 2170 2171 ------------------------- 2172 -- Check_Inner_Package -- 2173 ------------------------- 2174 2175 procedure Check_Inner_Package (Pack : Entity_Id) is 2176 E : Entity_Id; 2177 Un : constant Node_Id := Sinfo.Unit (Cnode); 2178 2179 function Check_Use_Clause (N : Node_Id) return Traverse_Result; 2180 -- If N is a use_clause for Pack, emit warning 2181 2182 procedure Check_Use_Clauses is new 2183 Traverse_Proc (Check_Use_Clause); 2184 2185 ---------------------- 2186 -- Check_Use_Clause -- 2187 ---------------------- 2188 2189 function Check_Use_Clause (N : Node_Id) return Traverse_Result is 2190 Nam : Node_Id; 2191 2192 begin 2193 if Nkind (N) = N_Use_Package_Clause then 2194 Nam := First (Names (N)); 2195 while Present (Nam) loop 2196 if Entity (Nam) = Pack then 2197 2198 -- Suppress message if any serious errors detected 2199 -- that turn off expansion, and thus result in false 2200 -- positives for this warning. 2201 2202 if Serious_Errors_Detected = 0 then 2203 Error_Msg_Qual_Level := 1; 2204 Error_Msg_NE -- CODEFIX 2205 ("?u?no entities of package& are referenced!", 2206 Nam, Pack); 2207 Error_Msg_Qual_Level := 0; 2208 end if; 2209 end if; 2210 2211 Next (Nam); 2212 end loop; 2213 end if; 2214 2215 return OK; 2216 end Check_Use_Clause; 2217 2218 -- Start of processing for Check_Inner_Package 2219 2220 begin 2221 E := First_Entity (Pack); 2222 while Present (E) loop 2223 if Referenced_Check_Spec (E) then 2224 return; 2225 end if; 2226 2227 Next_Entity (E); 2228 end loop; 2229 2230 -- No entities of the package are referenced. Check whether the 2231 -- reference to the package itself is a use clause, and if so 2232 -- place a warning on it. 2233 2234 Check_Use_Clauses (Un); 2235 end Check_Inner_Package; 2236 2237 ---------------------- 2238 -- Check_System_Aux -- 2239 ---------------------- 2240 2241 function Check_System_Aux return Boolean is 2242 Ent : Entity_Id; 2243 2244 begin 2245 if Chars (Lunit) = Name_System 2246 and then Scope (Lunit) = Standard_Standard 2247 and then Present_System_Aux 2248 then 2249 Ent := First_Entity (System_Aux_Id); 2250 while Present (Ent) loop 2251 if Referenced_Check_Spec (Ent) then 2252 return True; 2253 end if; 2254 2255 Next_Entity (Ent); 2256 end loop; 2257 end if; 2258 2259 return False; 2260 end Check_System_Aux; 2261 2262 --------------------------- 2263 -- Find_Package_Renaming -- 2264 --------------------------- 2265 2266 function Find_Package_Renaming 2267 (P : Entity_Id; 2268 L : Entity_Id) return Entity_Id 2269 is 2270 E1 : Entity_Id; 2271 R : Entity_Id; 2272 2273 begin 2274 Is_Visible_Renaming := False; 2275 2276 E1 := First_Entity (P); 2277 while Present (E1) loop 2278 if Ekind (E1) = E_Package and then Renamed_Object (E1) = L then 2279 Is_Visible_Renaming := not Is_Hidden (E1); 2280 return E1; 2281 2282 elsif Ekind (E1) = E_Package 2283 and then No (Renamed_Object (E1)) 2284 and then not Is_Generic_Instance (E1) 2285 then 2286 R := Find_Package_Renaming (E1, L); 2287 2288 if Present (R) then 2289 Is_Visible_Renaming := not Is_Hidden (R); 2290 return R; 2291 end if; 2292 end if; 2293 2294 Next_Entity (E1); 2295 end loop; 2296 2297 return Empty; 2298 end Find_Package_Renaming; 2299 2300 -------------------------- 2301 -- Has_Visible_Entities -- 2302 -------------------------- 2303 2304 function Has_Visible_Entities (P : Entity_Id) return Boolean is 2305 E : Entity_Id; 2306 2307 begin 2308 -- If unit in context is not a package, it is a subprogram that 2309 -- is not called or a generic unit that is not instantiated 2310 -- in the current unit, and warning is appropriate. 2311 2312 if Ekind (P) /= E_Package then 2313 return True; 2314 end if; 2315 2316 -- If unit comes from a limited_with clause, look for declaration 2317 -- of shadow entities. 2318 2319 if Present (Limited_View (P)) then 2320 E := First_Entity (Limited_View (P)); 2321 else 2322 E := First_Entity (P); 2323 end if; 2324 2325 while Present (E) and then E /= First_Private_Entity (P) loop 2326 if Comes_From_Source (E) or else Present (Limited_View (P)) then 2327 return True; 2328 end if; 2329 2330 Next_Entity (E); 2331 end loop; 2332 2333 return False; 2334 end Has_Visible_Entities; 2335 2336 -- Start of processing for Check_One_Unit 2337 2338 begin 2339 Cnode := Cunit (Unit); 2340 2341 -- Only do check in units that are part of the extended main unit. 2342 -- This is actually a necessary restriction, because in the case of 2343 -- subprogram acting as its own specification, there can be with's in 2344 -- subunits that we will not see. 2345 2346 if not In_Extended_Main_Source_Unit (Cnode) then 2347 return; 2348 2349 -- In configurable run time mode, we remove the bodies of non-inlined 2350 -- subprograms, which may lead to spurious warnings, which are 2351 -- clearly undesirable. 2352 2353 elsif Configurable_Run_Time_Mode 2354 and then Is_Predefined_File_Name (Unit_File_Name (Unit)) 2355 then 2356 return; 2357 end if; 2358 2359 -- Loop through context items in this unit 2360 2361 Item := First (Context_Items (Cnode)); 2362 while Present (Item) loop 2363 if Nkind (Item) = N_With_Clause 2364 and then not Implicit_With (Item) 2365 and then In_Extended_Main_Source_Unit (Item) 2366 2367 -- Guard for no entity present. Not clear under what conditions 2368 -- this happens, but it does occur, and since this is only a 2369 -- warning, we just suppress the warning in this case. 2370 2371 and then Nkind (Name (Item)) in N_Has_Entity 2372 and then Present (Entity (Name (Item))) 2373 then 2374 Lunit := Entity (Name (Item)); 2375 2376 -- Check if this unit is referenced (skip the check if this 2377 -- is explicitly marked by a pragma Unreferenced). 2378 2379 if not Referenced (Lunit) and then not Has_Unreferenced (Lunit) 2380 then 2381 -- Suppress warnings in internal units if not in -gnatg mode 2382 -- (these would be junk warnings for an application program, 2383 -- since they refer to problems in internal units). 2384 2385 if GNAT_Mode 2386 or else not Is_Internal_File_Name (Unit_File_Name (Unit)) 2387 then 2388 -- Here we definitely have a non-referenced unit. If it 2389 -- is the special call for a spec unit, then just set the 2390 -- flag to be read later. 2391 2392 if Unit = Spec_Unit then 2393 Set_Unreferenced_In_Spec (Item); 2394 2395 -- Otherwise simple unreferenced message, but skip this 2396 -- if no visible entities, because that is most likely a 2397 -- case where warning would be false positive (e.g. a 2398 -- package with only a linker options pragma and nothing 2399 -- else or a pragma elaborate with a body library task). 2400 2401 elsif Has_Visible_Entities (Entity (Name (Item))) then 2402 Error_Msg_N -- CODEFIX 2403 ("?u?unit& is not referenced!", Name (Item)); 2404 end if; 2405 end if; 2406 2407 -- If main unit is a renaming of this unit, then we consider 2408 -- the with to be OK (obviously it is needed in this case). 2409 -- This may be transitive: the unit in the with_clause may 2410 -- itself be a renaming, in which case both it and the main 2411 -- unit rename the same ultimate package. 2412 2413 elsif Present (Renamed_Entity (Munite)) 2414 and then 2415 (Renamed_Entity (Munite) = Lunit 2416 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit)) 2417 then 2418 null; 2419 2420 -- If this unit is referenced, and it is a package, we do 2421 -- another test, to see if any of the entities in the package 2422 -- are referenced. If none of the entities are referenced, we 2423 -- still post a warning. This occurs if the only use of the 2424 -- package is in a use clause, or in a package renaming 2425 -- declaration. This check is skipped for packages that are 2426 -- renamed in a spec, since the entities in such a package are 2427 -- visible to clients via the renaming. 2428 2429 elsif Ekind (Lunit) = E_Package 2430 and then not Renamed_In_Spec (Lunit) 2431 then 2432 -- If Is_Instantiated is set, it means that the package is 2433 -- implicitly instantiated (this is the case of parent 2434 -- instance or an actual for a generic package formal), and 2435 -- this counts as a reference. 2436 2437 if Is_Instantiated (Lunit) then 2438 null; 2439 2440 -- If no entities in package, and there is a pragma 2441 -- Elaborate_Body present, then assume that this with is 2442 -- done for purposes of this elaboration. 2443 2444 elsif No (First_Entity (Lunit)) 2445 and then Has_Pragma_Elaborate_Body (Lunit) 2446 then 2447 null; 2448 2449 -- Otherwise see if any entities have been referenced 2450 2451 else 2452 if Limited_Present (Item) then 2453 Ent := First_Entity (Limited_View (Lunit)); 2454 else 2455 Ent := First_Entity (Lunit); 2456 end if; 2457 2458 loop 2459 -- No more entities, and we did not find one that was 2460 -- referenced. Means we have a definite case of a with 2461 -- none of whose entities was referenced. 2462 2463 if No (Ent) then 2464 2465 -- If in spec, just set the flag 2466 2467 if Unit = Spec_Unit then 2468 Set_No_Entities_Ref_In_Spec (Item); 2469 2470 elsif Check_System_Aux then 2471 null; 2472 2473 -- Else the warning may be needed 2474 2475 else 2476 declare 2477 Eitem : constant Entity_Id := 2478 Entity (Name (Item)); 2479 2480 begin 2481 -- Warn if we unreferenced flag set and we 2482 -- have not had serious errors. The reason we 2483 -- inhibit the message if there are errors is 2484 -- to prevent false positives from disabling 2485 -- expansion. 2486 2487 if not Has_Unreferenced (Eitem) 2488 and then Serious_Errors_Detected = 0 2489 then 2490 -- Get possible package renaming 2491 2492 Pack := 2493 Find_Package_Renaming (Munite, Lunit); 2494 2495 -- No warning if either the package or its 2496 -- renaming is used as a generic actual. 2497 2498 if Used_As_Generic_Actual (Eitem) 2499 or else 2500 (Present (Pack) 2501 and then 2502 Used_As_Generic_Actual (Pack)) 2503 then 2504 exit; 2505 end if; 2506 2507 -- Here we give the warning 2508 2509 Error_Msg_N -- CODEFIX 2510 ("?u?no entities of & are referenced!", 2511 Name (Item)); 2512 2513 -- Flag renaming of package as well. If 2514 -- the original package has warnings off, 2515 -- we suppress the warning on the renaming 2516 -- as well. 2517 2518 if Present (Pack) 2519 and then not Has_Warnings_Off (Lunit) 2520 and then not Has_Unreferenced (Pack) 2521 then 2522 Error_Msg_NE -- CODEFIX 2523 ("?u?no entities of& are referenced!", 2524 Unit_Declaration_Node (Pack), Pack); 2525 end if; 2526 end if; 2527 end; 2528 end if; 2529 2530 exit; 2531 2532 -- Case of entity being referenced. The reference may 2533 -- come from a limited_with_clause, in which case the 2534 -- limited view of the entity carries the flag. 2535 2536 elsif Referenced_Check_Spec (Ent) 2537 or else Referenced_As_LHS_Check_Spec (Ent) 2538 or else Referenced_As_Out_Parameter_Check_Spec (Ent) 2539 or else 2540 (From_Limited_With (Ent) 2541 and then Is_Incomplete_Type (Ent) 2542 and then Present (Non_Limited_View (Ent)) 2543 and then Referenced (Non_Limited_View (Ent))) 2544 then 2545 -- This means that the with is indeed fine, in that 2546 -- it is definitely needed somewhere, and we can 2547 -- quit worrying about this one... 2548 2549 -- Except for one little detail: if either of the 2550 -- flags was set during spec processing, this is 2551 -- where we complain that the with could be moved 2552 -- from the spec. If the spec contains a visible 2553 -- renaming of the package, inhibit warning to move 2554 -- with_clause to body. 2555 2556 if Ekind (Munite) = E_Package_Body then 2557 Pack := 2558 Find_Package_Renaming 2559 (Spec_Entity (Munite), Lunit); 2560 else 2561 Pack := Empty; 2562 end if; 2563 2564 -- If a renaming is present in the spec do not warn 2565 -- because the body or child unit may depend on it. 2566 2567 if Present (Pack) 2568 and then Renamed_Entity (Pack) = Lunit 2569 then 2570 exit; 2571 2572 elsif Unreferenced_In_Spec (Item) then 2573 Error_Msg_N -- CODEFIX 2574 ("?u?unit& is not referenced in spec!", 2575 Name (Item)); 2576 2577 elsif No_Entities_Ref_In_Spec (Item) then 2578 Error_Msg_N -- CODEFIX 2579 ("?u?no entities of & are referenced in spec!", 2580 Name (Item)); 2581 2582 else 2583 if Ekind (Ent) = E_Package then 2584 Check_Inner_Package (Ent); 2585 end if; 2586 2587 exit; 2588 end if; 2589 2590 if not Is_Visible_Renaming then 2591 Error_Msg_N -- CODEFIX 2592 ("\?u?with clause might be moved to body!", 2593 Name (Item)); 2594 end if; 2595 2596 exit; 2597 2598 -- Move to next entity to continue search 2599 2600 else 2601 Next_Entity (Ent); 2602 end if; 2603 end loop; 2604 end if; 2605 2606 -- For a generic package, the only interesting kind of 2607 -- reference is an instantiation, since entities cannot be 2608 -- referenced directly. 2609 2610 elsif Is_Generic_Unit (Lunit) then 2611 2612 -- Unit was never instantiated, set flag for case of spec 2613 -- call, or give warning for normal call. 2614 2615 if not Is_Instantiated (Lunit) then 2616 if Unit = Spec_Unit then 2617 Set_Unreferenced_In_Spec (Item); 2618 else 2619 Error_Msg_N -- CODEFIX 2620 ("?u?unit& is never instantiated!", Name (Item)); 2621 end if; 2622 2623 -- If unit was indeed instantiated, make sure that flag is 2624 -- not set showing it was uninstantiated in the spec, and if 2625 -- so, give warning. 2626 2627 elsif Unreferenced_In_Spec (Item) then 2628 Error_Msg_N 2629 ("?u?unit& is not instantiated in spec!", Name (Item)); 2630 Error_Msg_N -- CODEFIX 2631 ("\?u?with clause can be moved to body!", Name (Item)); 2632 end if; 2633 end if; 2634 end if; 2635 2636 Next (Item); 2637 end loop; 2638 end Check_One_Unit; 2639 2640 -- Start of processing for Check_Unused_Withs 2641 2642 begin 2643 -- Immediate return if no semantics or warning flag not set 2644 2645 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then 2646 return; 2647 end if; 2648 2649 Process_Deferred_References; 2650 2651 -- Flag any unused with clauses. For a subunit, check only the units 2652 -- in its context, not those of the parent, which may be needed by other 2653 -- subunits. We will get the full warnings when we compile the parent, 2654 -- but the following is helpful when compiling a subunit by itself. 2655 2656 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then 2657 if Current_Sem_Unit = Main_Unit then 2658 Check_One_Unit (Main_Unit); 2659 end if; 2660 2661 return; 2662 end if; 2663 2664 -- Process specified units 2665 2666 if Spec_Unit = No_Unit then 2667 2668 -- For main call, check all units 2669 2670 for Unit in Main_Unit .. Last_Unit loop 2671 Check_One_Unit (Unit); 2672 end loop; 2673 2674 else 2675 -- For call for spec, check only the spec 2676 2677 Check_One_Unit (Spec_Unit); 2678 end if; 2679 end Check_Unused_Withs; 2680 2681 --------------------------------- 2682 -- Generic_Package_Spec_Entity -- 2683 --------------------------------- 2684 2685 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is 2686 S : Entity_Id; 2687 2688 begin 2689 if Is_Package_Body_Entity (E) then 2690 return False; 2691 2692 else 2693 S := Scope (E); 2694 loop 2695 if S = Standard_Standard then 2696 return False; 2697 2698 elsif Ekind (S) = E_Generic_Package then 2699 return True; 2700 2701 elsif Ekind (S) = E_Package then 2702 S := Scope (S); 2703 2704 else 2705 return False; 2706 end if; 2707 end loop; 2708 end if; 2709 end Generic_Package_Spec_Entity; 2710 2711 ---------------------- 2712 -- Goto_Spec_Entity -- 2713 ---------------------- 2714 2715 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is 2716 begin 2717 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2718 return Spec_Entity (E); 2719 else 2720 return E; 2721 end if; 2722 end Goto_Spec_Entity; 2723 2724 ------------------- 2725 -- Has_Junk_Name -- 2726 ------------------- 2727 2728 function Has_Junk_Name (E : Entity_Id) return Boolean is 2729 function Match (S : String) return Boolean; 2730 -- Return true if substring S is found in Name_Buffer (1 .. Name_Len) 2731 2732 ----------- 2733 -- Match -- 2734 ----------- 2735 2736 function Match (S : String) return Boolean is 2737 Slen1 : constant Integer := S'Length - 1; 2738 2739 begin 2740 for J in 1 .. Name_Len - S'Length + 1 loop 2741 if Name_Buffer (J .. J + Slen1) = S then 2742 return True; 2743 end if; 2744 end loop; 2745 2746 return False; 2747 end Match; 2748 2749 -- Start of processing for Has_Junk_Name 2750 2751 begin 2752 Get_Unqualified_Decoded_Name_String (Chars (E)); 2753 2754 return 2755 Match ("discard") or else 2756 Match ("dummy") or else 2757 Match ("ignore") or else 2758 Match ("junk") or else 2759 Match ("unused"); 2760 end Has_Junk_Name; 2761 2762 -------------------------------------- 2763 -- Has_Pragma_Unmodified_Check_Spec -- 2764 -------------------------------------- 2765 2766 function Has_Pragma_Unmodified_Check_Spec 2767 (E : Entity_Id) return Boolean 2768 is 2769 begin 2770 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2771 2772 -- Note: use of OR instead of OR ELSE here is deliberate, we want 2773 -- to mess with Unmodified flags on both body and spec entities. 2774 2775 return Has_Unmodified (E) 2776 or 2777 Has_Unmodified (Spec_Entity (E)); 2778 2779 else 2780 return Has_Unmodified (E); 2781 end if; 2782 end Has_Pragma_Unmodified_Check_Spec; 2783 2784 ---------------------------------------- 2785 -- Has_Pragma_Unreferenced_Check_Spec -- 2786 ---------------------------------------- 2787 2788 function Has_Pragma_Unreferenced_Check_Spec 2789 (E : Entity_Id) return Boolean 2790 is 2791 begin 2792 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2793 2794 -- Note: use of OR here instead of OR ELSE is deliberate, we want 2795 -- to mess with flags on both entities. 2796 2797 return Has_Unreferenced (E) 2798 or 2799 Has_Unreferenced (Spec_Entity (E)); 2800 2801 else 2802 return Has_Unreferenced (E); 2803 end if; 2804 end Has_Pragma_Unreferenced_Check_Spec; 2805 2806 ---------------- 2807 -- Initialize -- 2808 ---------------- 2809 2810 procedure Initialize is 2811 begin 2812 Warnings_Off_Pragmas.Init; 2813 Unreferenced_Entities.Init; 2814 In_Out_Warnings.Init; 2815 end Initialize; 2816 2817 ------------------------------------ 2818 -- Never_Set_In_Source_Check_Spec -- 2819 ------------------------------------ 2820 2821 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is 2822 begin 2823 if Is_Formal (E) and then Present (Spec_Entity (E)) then 2824 return Never_Set_In_Source (E) 2825 and then 2826 Never_Set_In_Source (Spec_Entity (E)); 2827 else 2828 return Never_Set_In_Source (E); 2829 end if; 2830 end Never_Set_In_Source_Check_Spec; 2831 2832 ------------------------------------- 2833 -- Operand_Has_Warnings_Suppressed -- 2834 ------------------------------------- 2835 2836 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is 2837 2838 function Check_For_Warnings (N : Node_Id) return Traverse_Result; 2839 -- Function used to check one node to see if it is or was originally 2840 -- a reference to an entity for which Warnings are off. If so, Abandon 2841 -- is returned, otherwise OK_Orig is returned to continue the traversal 2842 -- of the original expression. 2843 2844 function Traverse is new Traverse_Func (Check_For_Warnings); 2845 -- Function used to traverse tree looking for warnings 2846 2847 ------------------------ 2848 -- Check_For_Warnings -- 2849 ------------------------ 2850 2851 function Check_For_Warnings (N : Node_Id) return Traverse_Result is 2852 R : constant Node_Id := Original_Node (N); 2853 2854 begin 2855 if Nkind (R) in N_Has_Entity 2856 and then Present (Entity (R)) 2857 and then Has_Warnings_Off (Entity (R)) 2858 then 2859 return Abandon; 2860 else 2861 return OK_Orig; 2862 end if; 2863 end Check_For_Warnings; 2864 2865 -- Start of processing for Operand_Has_Warnings_Suppressed 2866 2867 begin 2868 return Traverse (N) = Abandon; 2869 2870 -- If any exception occurs, then something has gone wrong, and this is 2871 -- only a minor aesthetic issue anyway, so just say we did not find what 2872 -- we are looking for, rather than blow up. 2873 2874 exception 2875 when others => 2876 return False; 2877 end Operand_Has_Warnings_Suppressed; 2878 2879 ----------------------------------------- 2880 -- Output_Non_Modified_In_Out_Warnings -- 2881 ----------------------------------------- 2882 2883 procedure Output_Non_Modified_In_Out_Warnings is 2884 2885 function No_Warn_On_In_Out (E : Entity_Id) return Boolean; 2886 -- Given a formal parameter entity E, determines if there is a reason to 2887 -- suppress IN OUT warnings (not modified, could be IN) for formals of 2888 -- the subprogram. We suppress these warnings if Warnings Off is set, or 2889 -- if we have seen the address of the subprogram being taken, or if the 2890 -- subprogram is used as a generic actual (in the latter cases the 2891 -- context may force use of IN OUT, even if the parameter is not 2892 -- modifies for this particular case. 2893 2894 ----------------------- 2895 -- No_Warn_On_In_Out -- 2896 ----------------------- 2897 2898 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is 2899 S : constant Entity_Id := Scope (E); 2900 SE : constant Entity_Id := Spec_Entity (E); 2901 2902 begin 2903 -- Do not warn if address is taken, since funny business may be going 2904 -- on in treating the parameter indirectly as IN OUT. 2905 2906 if Address_Taken (S) 2907 or else (Present (SE) and then Address_Taken (Scope (SE))) 2908 then 2909 return True; 2910 2911 -- Do not warn if used as a generic actual, since the generic may be 2912 -- what is forcing the use of an "unnecessary" IN OUT. 2913 2914 elsif Used_As_Generic_Actual (S) 2915 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE))) 2916 then 2917 return True; 2918 2919 -- Else test warnings off 2920 2921 elsif Warnings_Off_Check_Spec (S) then 2922 return True; 2923 2924 -- All tests for suppressing warning failed 2925 2926 else 2927 return False; 2928 end if; 2929 end No_Warn_On_In_Out; 2930 2931 -- Start of processing for Output_Non_Modified_In_Out_Warnings 2932 2933 begin 2934 -- Loop through entities for which a warning may be needed 2935 2936 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop 2937 declare 2938 E1 : constant Entity_Id := In_Out_Warnings.Table (J); 2939 2940 begin 2941 -- Suppress warning in specific cases (see details in comments for 2942 -- No_Warn_On_In_Out), or if there is a pragma Unmodified. 2943 2944 if Has_Pragma_Unmodified_Check_Spec (E1) 2945 or else No_Warn_On_In_Out (E1) 2946 then 2947 null; 2948 2949 -- Here we generate the warning 2950 2951 else 2952 -- If -gnatwc is set then output message that we could be IN 2953 2954 if not Is_Trivial_Subprogram (Scope (E1)) then 2955 if Warn_On_Constant then 2956 Error_Msg_N 2957 ("?u?formal parameter & is not modified!", E1); 2958 Error_Msg_N 2959 ("\?u?mode could be IN instead of `IN OUT`!", E1); 2960 2961 -- We do not generate warnings for IN OUT parameters 2962 -- unless we have at least -gnatwu. This is deliberately 2963 -- inconsistent with the treatment of variables, but 2964 -- otherwise we get too many unexpected warnings in 2965 -- default mode. 2966 2967 elsif Check_Unreferenced then 2968 Error_Msg_N 2969 ("?u?formal parameter& is read but " 2970 & "never assigned!", E1); 2971 end if; 2972 end if; 2973 2974 -- Kill any other warnings on this entity, since this is the 2975 -- one that should dominate any other unreferenced warning. 2976 2977 Set_Warnings_Off (E1); 2978 end if; 2979 end; 2980 end loop; 2981 end Output_Non_Modified_In_Out_Warnings; 2982 2983 ---------------------------------------- 2984 -- Output_Obsolescent_Entity_Warnings -- 2985 ---------------------------------------- 2986 2987 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is 2988 P : constant Node_Id := Parent (N); 2989 S : Entity_Id; 2990 2991 begin 2992 S := Current_Scope; 2993 2994 -- Do not output message if we are the scope of standard. This means 2995 -- we have a reference from a context clause from when it is originally 2996 -- processed, and that's too early to tell whether it is an obsolescent 2997 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make 2998 -- sure that we have a later call when the scope is available. This test 2999 -- also eliminates all messages for use clauses, which is fine (we do 3000 -- not want messages for use clauses, since they are always redundant 3001 -- with respect to the associated with clause). 3002 3003 if S = Standard_Standard then 3004 return; 3005 end if; 3006 3007 -- Do not output message if we are in scope of an obsolescent package 3008 -- or subprogram. 3009 3010 loop 3011 if Is_Obsolescent (S) then 3012 return; 3013 end if; 3014 3015 S := Scope (S); 3016 exit when S = Standard_Standard; 3017 end loop; 3018 3019 -- Here we will output the message 3020 3021 Error_Msg_Sloc := Sloc (E); 3022 3023 -- Case of with clause 3024 3025 if Nkind (P) = N_With_Clause then 3026 if Ekind (E) = E_Package then 3027 Error_Msg_NE 3028 ("?j?with of obsolescent package& declared#", N, E); 3029 elsif Ekind (E) = E_Procedure then 3030 Error_Msg_NE 3031 ("?j?with of obsolescent procedure& declared#", N, E); 3032 else 3033 Error_Msg_NE 3034 ("??with of obsolescent function& declared#", N, E); 3035 end if; 3036 3037 -- If we do not have a with clause, then ignore any reference to an 3038 -- obsolescent package name. We only want to give the one warning of 3039 -- withing the package, not one each time it is used to qualify. 3040 3041 elsif Ekind (E) = E_Package then 3042 return; 3043 3044 -- Procedure call statement 3045 3046 elsif Nkind (P) = N_Procedure_Call_Statement then 3047 Error_Msg_NE 3048 ("??call to obsolescent procedure& declared#", N, E); 3049 3050 -- Function call 3051 3052 elsif Nkind (P) = N_Function_Call then 3053 Error_Msg_NE 3054 ("??call to obsolescent function& declared#", N, E); 3055 3056 -- Reference to obsolescent type 3057 3058 elsif Is_Type (E) then 3059 Error_Msg_NE 3060 ("??reference to obsolescent type& declared#", N, E); 3061 3062 -- Reference to obsolescent component 3063 3064 elsif Ekind_In (E, E_Component, E_Discriminant) then 3065 Error_Msg_NE 3066 ("??reference to obsolescent component& declared#", N, E); 3067 3068 -- Reference to obsolescent variable 3069 3070 elsif Ekind (E) = E_Variable then 3071 Error_Msg_NE 3072 ("??reference to obsolescent variable& declared#", N, E); 3073 3074 -- Reference to obsolescent constant 3075 3076 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then 3077 Error_Msg_NE 3078 ("??reference to obsolescent constant& declared#", N, E); 3079 3080 -- Reference to obsolescent enumeration literal 3081 3082 elsif Ekind (E) = E_Enumeration_Literal then 3083 Error_Msg_NE 3084 ("??reference to obsolescent enumeration literal& declared#", N, E); 3085 3086 -- Generic message for any other case we missed 3087 3088 else 3089 Error_Msg_NE 3090 ("??reference to obsolescent entity& declared#", N, E); 3091 end if; 3092 3093 -- Output additional warning if present 3094 3095 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop 3096 if Obsolescent_Warnings.Table (J).Ent = E then 3097 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg); 3098 Error_Msg_Strlen := Name_Len; 3099 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len); 3100 Error_Msg_N ("\\??~", N); 3101 exit; 3102 end if; 3103 end loop; 3104 end Output_Obsolescent_Entity_Warnings; 3105 3106 ---------------------------------- 3107 -- Output_Unreferenced_Messages -- 3108 ---------------------------------- 3109 3110 procedure Output_Unreferenced_Messages is 3111 begin 3112 for J in Unreferenced_Entities.First .. Unreferenced_Entities.Last loop 3113 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J)); 3114 end loop; 3115 end Output_Unreferenced_Messages; 3116 3117 ----------------------------------------- 3118 -- Output_Unused_Warnings_Off_Warnings -- 3119 ----------------------------------------- 3120 3121 procedure Output_Unused_Warnings_Off_Warnings is 3122 begin 3123 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop 3124 declare 3125 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J); 3126 N : Node_Id renames Wentry.N; 3127 E : Node_Id renames Wentry.E; 3128 3129 begin 3130 -- Turn off Warnings_Off, or we won't get the warning 3131 3132 Set_Warnings_Off (E, False); 3133 3134 -- Nothing to do if pragma was used to suppress a general warning 3135 3136 if Warnings_Off_Used (E) then 3137 null; 3138 3139 -- If pragma was used both in unmodified and unreferenced contexts 3140 -- then that's as good as the general case, no warning. 3141 3142 elsif Warnings_Off_Used_Unmodified (E) 3143 and 3144 Warnings_Off_Used_Unreferenced (E) 3145 then 3146 null; 3147 3148 -- Used only in context where Unmodified would have worked 3149 3150 elsif Warnings_Off_Used_Unmodified (E) then 3151 Error_Msg_NE 3152 ("?W?could use Unmodified instead of " 3153 & "Warnings Off for &", Pragma_Identifier (N), E); 3154 3155 -- Used only in context where Unreferenced would have worked 3156 3157 elsif Warnings_Off_Used_Unreferenced (E) then 3158 Error_Msg_NE 3159 ("?W?could use Unreferenced instead of " 3160 & "Warnings Off for &", Pragma_Identifier (N), E); 3161 3162 -- Not used at all 3163 3164 else 3165 Error_Msg_NE 3166 ("?W?pragma Warnings Off for & unused, " 3167 & "could be omitted", N, E); 3168 end if; 3169 end; 3170 end loop; 3171 end Output_Unused_Warnings_Off_Warnings; 3172 3173 --------------------------- 3174 -- Referenced_Check_Spec -- 3175 --------------------------- 3176 3177 function Referenced_Check_Spec (E : Entity_Id) return Boolean is 3178 begin 3179 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3180 return Referenced (E) or else Referenced (Spec_Entity (E)); 3181 else 3182 return Referenced (E); 3183 end if; 3184 end Referenced_Check_Spec; 3185 3186 ---------------------------------- 3187 -- Referenced_As_LHS_Check_Spec -- 3188 ---------------------------------- 3189 3190 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is 3191 begin 3192 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3193 return Referenced_As_LHS (E) 3194 or else Referenced_As_LHS (Spec_Entity (E)); 3195 else 3196 return Referenced_As_LHS (E); 3197 end if; 3198 end Referenced_As_LHS_Check_Spec; 3199 3200 -------------------------------------------- 3201 -- Referenced_As_Out_Parameter_Check_Spec -- 3202 -------------------------------------------- 3203 3204 function Referenced_As_Out_Parameter_Check_Spec 3205 (E : Entity_Id) return Boolean 3206 is 3207 begin 3208 if Is_Formal (E) and then Present (Spec_Entity (E)) then 3209 return Referenced_As_Out_Parameter (E) 3210 or else Referenced_As_Out_Parameter (Spec_Entity (E)); 3211 else 3212 return Referenced_As_Out_Parameter (E); 3213 end if; 3214 end Referenced_As_Out_Parameter_Check_Spec; 3215 3216 ----------------------------- 3217 -- Warn_On_Known_Condition -- 3218 ----------------------------- 3219 3220 procedure Warn_On_Known_Condition (C : Node_Id) is 3221 P : Node_Id; 3222 Orig : constant Node_Id := Original_Node (C); 3223 Test_Result : Boolean; 3224 3225 function Is_Known_Branch return Boolean; 3226 -- If the type of the condition is Boolean, the constant value of the 3227 -- condition is a boolean literal. If the type is a derived boolean 3228 -- type, the constant is wrapped in a type conversion of the derived 3229 -- literal. If the value of the condition is not a literal, no warnings 3230 -- can be produced. This function returns True if the result can be 3231 -- determined, and Test_Result is set True/False accordingly. Otherwise 3232 -- False is returned, and Test_Result is unchanged. 3233 3234 procedure Track (N : Node_Id; Loc : Node_Id); 3235 -- Adds continuation warning(s) pointing to reason (assignment or test) 3236 -- for the operand of the conditional having a known value (or at least 3237 -- enough is known about the value to issue the warning). N is the node 3238 -- which is judged to have a known value. Loc is the warning location. 3239 3240 --------------------- 3241 -- Is_Known_Branch -- 3242 --------------------- 3243 3244 function Is_Known_Branch return Boolean is 3245 begin 3246 if Etype (C) = Standard_Boolean 3247 and then Is_Entity_Name (C) 3248 and then 3249 (Entity (C) = Standard_False or else Entity (C) = Standard_True) 3250 then 3251 Test_Result := Entity (C) = Standard_True; 3252 return True; 3253 3254 elsif Is_Boolean_Type (Etype (C)) 3255 and then Nkind (C) = N_Unchecked_Type_Conversion 3256 and then Is_Entity_Name (Expression (C)) 3257 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal 3258 then 3259 Test_Result := 3260 Chars (Entity (Expression (C))) = Chars (Standard_True); 3261 return True; 3262 3263 else 3264 return False; 3265 end if; 3266 end Is_Known_Branch; 3267 3268 ----------- 3269 -- Track -- 3270 ----------- 3271 3272 procedure Track (N : Node_Id; Loc : Node_Id) is 3273 Nod : constant Node_Id := Original_Node (N); 3274 3275 begin 3276 if Nkind (Nod) in N_Op_Compare then 3277 Track (Left_Opnd (Nod), Loc); 3278 Track (Right_Opnd (Nod), Loc); 3279 3280 elsif Is_Entity_Name (Nod) and then Is_Object (Entity (Nod)) then 3281 declare 3282 CV : constant Node_Id := Current_Value (Entity (Nod)); 3283 3284 begin 3285 if Present (CV) then 3286 Error_Msg_Sloc := Sloc (CV); 3287 3288 if Nkind (CV) not in N_Subexpr then 3289 Error_Msg_N ("\\??(see test #)", Loc); 3290 3291 elsif Nkind (Parent (CV)) = 3292 N_Case_Statement_Alternative 3293 then 3294 Error_Msg_N ("\\??(see case alternative #)", Loc); 3295 3296 else 3297 Error_Msg_N ("\\??(see assignment #)", Loc); 3298 end if; 3299 end if; 3300 end; 3301 end if; 3302 end Track; 3303 3304 -- Start of processing for Warn_On_Known_Condition 3305 3306 begin 3307 -- Adjust SCO condition if from source 3308 3309 if Generate_SCO 3310 and then Comes_From_Source (Orig) 3311 and then Is_Known_Branch 3312 then 3313 declare 3314 Atrue : Boolean; 3315 3316 begin 3317 Atrue := Test_Result; 3318 3319 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then 3320 Atrue := not Atrue; 3321 end if; 3322 3323 Set_SCO_Condition (Orig, Atrue); 3324 end; 3325 end if; 3326 3327 -- Argument replacement in an inlined body can make conditions static. 3328 -- Do not emit warnings in this case. 3329 3330 if In_Inlined_Body then 3331 return; 3332 end if; 3333 3334 if Constant_Condition_Warnings 3335 and then Is_Known_Branch 3336 and then Comes_From_Source (Orig) 3337 and then not In_Instance 3338 then 3339 -- Don't warn if comparison of result of attribute against a constant 3340 -- value, since this is likely legitimate conditional compilation. 3341 3342 if Nkind (Orig) in N_Op_Compare 3343 and then Compile_Time_Known_Value (Right_Opnd (Orig)) 3344 and then Nkind (Original_Node (Left_Opnd (Orig))) = 3345 N_Attribute_Reference 3346 then 3347 return; 3348 end if; 3349 3350 -- See if this is in a statement or a declaration 3351 3352 P := Parent (C); 3353 loop 3354 -- If tree is not attached, do not issue warning (this is very 3355 -- peculiar, and probably arises from some other error condition) 3356 3357 if No (P) then 3358 return; 3359 3360 -- If we are in a declaration, then no warning, since in practice 3361 -- conditionals in declarations are used for intended tests which 3362 -- may be known at compile time, e.g. things like 3363 3364 -- x : constant Integer := 2 + (Word'Size = 32); 3365 3366 -- And a warning is annoying in such cases 3367 3368 elsif Nkind (P) in N_Declaration 3369 or else 3370 Nkind (P) in N_Later_Decl_Item 3371 then 3372 return; 3373 3374 -- Don't warn in assert or check pragma, since presumably tests in 3375 -- such a context are very definitely intended, and might well be 3376 -- known at compile time. Note that we have to test the original 3377 -- node, since assert pragmas get rewritten at analysis time. 3378 3379 elsif Nkind (Original_Node (P)) = N_Pragma 3380 and then Nam_In (Pragma_Name (Original_Node (P)), Name_Assert, 3381 Name_Check) 3382 then 3383 return; 3384 end if; 3385 3386 exit when Is_Statement (P); 3387 P := Parent (P); 3388 end loop; 3389 3390 -- Here we issue the warning unless some sub-operand has warnings 3391 -- set off, in which case we suppress the warning for the node. If 3392 -- the original expression is an inequality, it has been expanded 3393 -- into a negation, and the value of the original expression is the 3394 -- negation of the equality. If the expression is an entity that 3395 -- appears within a negation, it is clearer to flag the negation 3396 -- itself, and report on its constant value. 3397 3398 if not Operand_Has_Warnings_Suppressed (C) then 3399 declare 3400 True_Branch : Boolean := Test_Result; 3401 Cond : Node_Id := C; 3402 3403 begin 3404 if Present (Parent (C)) 3405 and then Nkind (Parent (C)) = N_Op_Not 3406 then 3407 True_Branch := not True_Branch; 3408 Cond := Parent (C); 3409 end if; 3410 3411 -- Condition always True 3412 3413 if True_Branch then 3414 if Is_Entity_Name (Original_Node (C)) 3415 and then Nkind (Cond) /= N_Op_Not 3416 then 3417 Error_Msg_NE 3418 ("object & is always True at this point?c?", 3419 Cond, Original_Node (C)); 3420 Track (Original_Node (C), Cond); 3421 3422 else 3423 Error_Msg_N ("condition is always True?c?", Cond); 3424 Track (Cond, Cond); 3425 end if; 3426 3427 -- Condition always False 3428 3429 else 3430 if Is_Entity_Name (Original_Node (C)) 3431 and then Nkind (Cond) /= N_Op_Not 3432 then 3433 Error_Msg_NE 3434 ("object & is always False at this point?c?", 3435 Cond, Original_Node (C)); 3436 Track (Original_Node (C), Cond); 3437 3438 else 3439 Error_Msg_N ("condition is always False?c?", Cond); 3440 Track (Cond, Cond); 3441 end if; 3442 end if; 3443 end; 3444 end if; 3445 end if; 3446 end Warn_On_Known_Condition; 3447 3448 --------------------------------------- 3449 -- Warn_On_Modified_As_Out_Parameter -- 3450 --------------------------------------- 3451 3452 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is 3453 begin 3454 return 3455 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E)) 3456 or else Warn_On_All_Unread_Out_Parameters; 3457 end Warn_On_Modified_As_Out_Parameter; 3458 3459 --------------------------------- 3460 -- Warn_On_Overlapping_Actuals -- 3461 --------------------------------- 3462 3463 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is 3464 Act1, Act2 : Node_Id; 3465 Form1, Form2 : Entity_Id; 3466 3467 function Is_Covered_Formal (Formal : Node_Id) return Boolean; 3468 -- Return True if Formal is covered by the rule 3469 3470 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean; 3471 -- Two names are known to refer to the same object if the two names 3472 -- are known to denote the same object; or one of the names is a 3473 -- selected_component, indexed_component, or slice and its prefix is 3474 -- known to refer to the same object as the other name; or one of the 3475 -- two names statically denotes a renaming declaration whose renamed 3476 -- object_name is known to refer to the same object as the other name 3477 -- (RM 6.4.1(6.11/3)) 3478 3479 ----------------------- 3480 -- Refer_Same_Object -- 3481 ----------------------- 3482 3483 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is 3484 begin 3485 return Denotes_Same_Object (Act1, Act2) 3486 or else Denotes_Same_Prefix (Act1, Act2); 3487 end Refer_Same_Object; 3488 3489 ----------------------- 3490 -- Is_Covered_Formal -- 3491 ----------------------- 3492 3493 function Is_Covered_Formal (Formal : Node_Id) return Boolean is 3494 begin 3495 return 3496 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter) 3497 and then (Is_Elementary_Type (Etype (Formal)) 3498 or else Is_Record_Type (Etype (Formal)) 3499 or else Is_Array_Type (Etype (Formal))); 3500 end Is_Covered_Formal; 3501 3502 begin 3503 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then 3504 return; 3505 end if; 3506 3507 -- Exclude calls rewritten as enumeration literals 3508 3509 if Nkind (N) not in N_Subprogram_Call 3510 and then Nkind (N) /= N_Entry_Call_Statement 3511 then 3512 return; 3513 end if; 3514 3515 -- If a call C has two or more parameters of mode in out or out that are 3516 -- of an elementary type, then the call is legal only if for each name 3517 -- N that is passed as a parameter of mode in out or out to the call C, 3518 -- there is no other name among the other parameters of mode in out or 3519 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3)) 3520 3521 -- If appropriate warning switch is set, we also report warnings on 3522 -- overlapping parameters that are record types or array types. 3523 3524 Form1 := First_Formal (Subp); 3525 Act1 := First_Actual (N); 3526 while Present (Form1) and then Present (Act1) loop 3527 if Is_Covered_Formal (Form1) then 3528 Form2 := First_Formal (Subp); 3529 Act2 := First_Actual (N); 3530 while Present (Form2) and then Present (Act2) loop 3531 if Form1 /= Form2 3532 and then Is_Covered_Formal (Form2) 3533 and then Refer_Same_Object (Act1, Act2) 3534 then 3535 -- Guard against previous errors 3536 3537 if Error_Posted (N) 3538 or else No (Etype (Act1)) 3539 or else No (Etype (Act2)) 3540 then 3541 null; 3542 3543 -- If the actual is a function call in prefix notation, 3544 -- there is no real overlap. 3545 3546 elsif Nkind (Act2) = N_Function_Call then 3547 null; 3548 3549 -- If type is not by-copy, assume that aliasing is intended 3550 3551 elsif 3552 Present (Underlying_Type (Etype (Form1))) 3553 and then 3554 (Is_By_Reference_Type (Underlying_Type (Etype (Form1))) 3555 or else 3556 Convention (Underlying_Type (Etype (Form1))) = 3557 Convention_Ada_Pass_By_Reference) 3558 then 3559 null; 3560 3561 -- Under Ada 2012 we only report warnings on overlapping 3562 -- arrays and record types if switch is set. 3563 3564 elsif Ada_Version >= Ada_2012 3565 and then not Is_Elementary_Type (Etype (Form1)) 3566 and then not Warn_On_Overlap 3567 then 3568 null; 3569 3570 -- Here we may need to issue overlap message 3571 3572 else 3573 Error_Msg_Warn := 3574 3575 -- Overlap checking is an error only in Ada 2012. For 3576 -- earlier versions of Ada, this is a warning. 3577 3578 Ada_Version < Ada_2012 3579 3580 -- Overlap is only illegal in Ada 2012 in the case of 3581 -- elementary types (passed by copy). For other types, 3582 -- we always have a warning in all Ada versions. 3583 3584 or else not Is_Elementary_Type (Etype (Form1)) 3585 3586 -- Finally, debug flag -gnatd.E changes the error to a 3587 -- warning even in Ada 2012 mode. 3588 3589 or else Error_To_Warning; 3590 3591 declare 3592 Act : Node_Id; 3593 Form : Entity_Id; 3594 3595 begin 3596 -- Find matching actual 3597 3598 Act := First_Actual (N); 3599 Form := First_Formal (Subp); 3600 while Act /= Act2 loop 3601 Next_Formal (Form); 3602 Next_Actual (Act); 3603 end loop; 3604 3605 if Is_Elementary_Type (Etype (Act1)) 3606 and then Ekind (Form2) = E_In_Parameter 3607 then 3608 null; -- No real aliasing 3609 3610 elsif Is_Elementary_Type (Etype (Act2)) 3611 and then Ekind (Form2) = E_In_Parameter 3612 then 3613 null; -- Ditto 3614 3615 -- If the call was written in prefix notation, and 3616 -- thus its prefix before rewriting was a selected 3617 -- component, count only visible actuals in the call. 3618 3619 elsif Is_Entity_Name (First_Actual (N)) 3620 and then Nkind (Original_Node (N)) = Nkind (N) 3621 and then Nkind (Name (Original_Node (N))) = 3622 N_Selected_Component 3623 and then 3624 Is_Entity_Name (Prefix (Name (Original_Node (N)))) 3625 and then 3626 Entity (Prefix (Name (Original_Node (N)))) = 3627 Entity (First_Actual (N)) 3628 then 3629 if Act1 = First_Actual (N) then 3630 Error_Msg_FE 3631 ("<<`IN OUT` prefix overlaps with " 3632 & "actual for&", Act1, Form); 3633 3634 else 3635 -- For greater clarity, give name of formal 3636 3637 Error_Msg_Node_2 := Form; 3638 Error_Msg_FE 3639 ("<<writable actual for & overlaps with " 3640 & "actual for&", Act1, Form); 3641 end if; 3642 3643 else 3644 -- For greater clarity, give name of formal 3645 3646 Error_Msg_Node_2 := Form; 3647 3648 -- This is one of the messages 3649 3650 Error_Msg_FE 3651 ("<<writable actual for & overlaps with " 3652 & "actual for&", Act1, Form1); 3653 end if; 3654 end; 3655 end if; 3656 3657 return; 3658 end if; 3659 3660 Next_Formal (Form2); 3661 Next_Actual (Act2); 3662 end loop; 3663 end if; 3664 3665 Next_Formal (Form1); 3666 Next_Actual (Act1); 3667 end loop; 3668 end Warn_On_Overlapping_Actuals; 3669 3670 ------------------------------ 3671 -- Warn_On_Suspicious_Index -- 3672 ------------------------------ 3673 3674 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is 3675 3676 Low_Bound : Uint; 3677 -- Set to lower bound for a suspicious type 3678 3679 Ent : Entity_Id; 3680 -- Entity for array reference 3681 3682 Typ : Entity_Id; 3683 -- Array type 3684 3685 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean; 3686 -- Tests to see if Typ is a type for which we may have a suspicious 3687 -- index, namely an unconstrained array type, whose lower bound is 3688 -- either zero or one. If so, True is returned, and Low_Bound is set 3689 -- to this lower bound. If not, False is returned, and Low_Bound is 3690 -- undefined on return. 3691 -- 3692 -- For now, we limit this to standard string types, so any other 3693 -- unconstrained types return False. We may change our minds on this 3694 -- later on, but strings seem the most important case. 3695 3696 procedure Test_Suspicious_Index; 3697 -- Test if index is of suspicious type and if so, generate warning 3698 3699 ------------------------ 3700 -- Is_Suspicious_Type -- 3701 ------------------------ 3702 3703 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is 3704 LB : Node_Id; 3705 3706 begin 3707 if Is_Array_Type (Typ) 3708 and then not Is_Constrained (Typ) 3709 and then Number_Dimensions (Typ) = 1 3710 and then Is_Standard_String_Type (Typ) 3711 and then not Has_Warnings_Off (Typ) 3712 then 3713 LB := Type_Low_Bound (Etype (First_Index (Typ))); 3714 3715 if Compile_Time_Known_Value (LB) then 3716 Low_Bound := Expr_Value (LB); 3717 return Low_Bound = Uint_0 or else Low_Bound = Uint_1; 3718 end if; 3719 end if; 3720 3721 return False; 3722 end Is_Suspicious_Type; 3723 3724 --------------------------- 3725 -- Test_Suspicious_Index -- 3726 --------------------------- 3727 3728 procedure Test_Suspicious_Index is 3729 3730 function Length_Reference (N : Node_Id) return Boolean; 3731 -- Check if node N is of the form Name'Length 3732 3733 procedure Warn1; 3734 -- Generate first warning line 3735 3736 ---------------------- 3737 -- Length_Reference -- 3738 ---------------------- 3739 3740 function Length_Reference (N : Node_Id) return Boolean is 3741 R : constant Node_Id := Original_Node (N); 3742 begin 3743 return 3744 Nkind (R) = N_Attribute_Reference 3745 and then Attribute_Name (R) = Name_Length 3746 and then Is_Entity_Name (Prefix (R)) 3747 and then Entity (Prefix (R)) = Ent; 3748 end Length_Reference; 3749 3750 ----------- 3751 -- Warn1 -- 3752 ----------- 3753 3754 procedure Warn1 is 3755 begin 3756 Error_Msg_Uint_1 := Low_Bound; 3757 Error_Msg_FE -- CODEFIX 3758 ("?w?index for& may assume lower bound of^", X, Ent); 3759 end Warn1; 3760 3761 -- Start of processing for Test_Suspicious_Index 3762 3763 begin 3764 -- Nothing to do if subscript does not come from source (we don't 3765 -- want to give garbage warnings on compiler expanded code, e.g. the 3766 -- loops generated for slice assignments. Such junk warnings would 3767 -- be placed on source constructs with no subscript in sight). 3768 3769 if not Comes_From_Source (Original_Node (X)) then 3770 return; 3771 end if; 3772 3773 -- Case where subscript is a constant integer 3774 3775 if Nkind (X) = N_Integer_Literal then 3776 Warn1; 3777 3778 -- Case where original form of subscript is an integer literal 3779 3780 if Nkind (Original_Node (X)) = N_Integer_Literal then 3781 if Intval (X) = Low_Bound then 3782 Error_Msg_FE -- CODEFIX 3783 ("\?w?suggested replacement: `&''First`", X, Ent); 3784 else 3785 Error_Msg_Uint_1 := Intval (X) - Low_Bound; 3786 Error_Msg_FE -- CODEFIX 3787 ("\?w?suggested replacement: `&''First + ^`", X, Ent); 3788 3789 end if; 3790 3791 -- Case where original form of subscript is more complex 3792 3793 else 3794 -- Build string X'First - 1 + expression where the expression 3795 -- is the original subscript. If the expression starts with "1 3796 -- + ", then the "- 1 + 1" is elided. 3797 3798 Error_Msg_String (1 .. 13) := "'First - 1 + "; 3799 Error_Msg_Strlen := 13; 3800 3801 declare 3802 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X))); 3803 Tref : constant Source_Buffer_Ptr := 3804 Source_Text (Get_Source_File_Index (Sref)); 3805 -- Tref (Sref) is used to scan the subscript 3806 3807 Pctr : Natural; 3808 -- Parentheses counter when scanning subscript 3809 3810 begin 3811 -- Tref (Sref) points to start of subscript 3812 3813 -- Elide - 1 if subscript starts with 1 + 3814 3815 if Tref (Sref .. Sref + 2) = "1 +" then 3816 Error_Msg_Strlen := Error_Msg_Strlen - 6; 3817 Sref := Sref + 2; 3818 3819 elsif Tref (Sref .. Sref + 1) = "1+" then 3820 Error_Msg_Strlen := Error_Msg_Strlen - 6; 3821 Sref := Sref + 1; 3822 end if; 3823 3824 -- Now we will copy the subscript to the string buffer 3825 3826 Pctr := 0; 3827 loop 3828 -- Count parens, exit if terminating right paren. Note 3829 -- check to ignore paren appearing as character literal. 3830 3831 if Tref (Sref + 1) = ''' 3832 and then 3833 Tref (Sref - 1) = ''' 3834 then 3835 null; 3836 else 3837 if Tref (Sref) = '(' then 3838 Pctr := Pctr + 1; 3839 elsif Tref (Sref) = ')' then 3840 exit when Pctr = 0; 3841 Pctr := Pctr - 1; 3842 end if; 3843 end if; 3844 3845 -- Done if terminating double dot (slice case) 3846 3847 exit when Pctr = 0 3848 and then (Tref (Sref .. Sref + 1) = ".." 3849 or else 3850 Tref (Sref .. Sref + 2) = " .."); 3851 3852 -- Quit if we have hit EOF character, something wrong 3853 3854 if Tref (Sref) = EOF then 3855 return; 3856 end if; 3857 3858 -- String literals are too much of a pain to handle 3859 3860 if Tref (Sref) = '"' or else Tref (Sref) = '%' then 3861 return; 3862 end if; 3863 3864 -- If we have a 'Range reference, then this is a case 3865 -- where we cannot easily give a replacement. Don't try. 3866 3867 if Tref (Sref .. Sref + 4) = "range" 3868 and then Tref (Sref - 1) < 'A' 3869 and then Tref (Sref + 5) < 'A' 3870 then 3871 return; 3872 end if; 3873 3874 -- Else store next character 3875 3876 Error_Msg_Strlen := Error_Msg_Strlen + 1; 3877 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref); 3878 Sref := Sref + 1; 3879 3880 -- If we get more than 40 characters then the expression 3881 -- is too long to copy, or something has gone wrong. In 3882 -- either case, just skip the attempt at a suggested fix. 3883 3884 if Error_Msg_Strlen > 40 then 3885 return; 3886 end if; 3887 end loop; 3888 end; 3889 3890 -- Replacement subscript is now in string buffer 3891 3892 Error_Msg_FE -- CODEFIX 3893 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent); 3894 end if; 3895 3896 -- Case where subscript is of the form X'Length 3897 3898 elsif Length_Reference (X) then 3899 Warn1; 3900 Error_Msg_Node_2 := Ent; 3901 Error_Msg_FE 3902 ("\?w?suggest replacement of `&''Length` by `&''Last`", 3903 X, Ent); 3904 3905 -- Case where subscript is of the form X'Length - expression 3906 3907 elsif Nkind (X) = N_Op_Subtract 3908 and then Length_Reference (Left_Opnd (X)) 3909 then 3910 Warn1; 3911 Error_Msg_Node_2 := Ent; 3912 Error_Msg_FE 3913 ("\?w?suggest replacement of `&''Length` by `&''Last`", 3914 Left_Opnd (X), Ent); 3915 end if; 3916 end Test_Suspicious_Index; 3917 3918 -- Start of processing for Warn_On_Suspicious_Index 3919 3920 begin 3921 -- Only process if warnings activated 3922 3923 if Warn_On_Assumed_Low_Bound then 3924 3925 -- Test if array is simple entity name 3926 3927 if Is_Entity_Name (Name) then 3928 3929 -- Test if array is parameter of unconstrained string type 3930 3931 Ent := Entity (Name); 3932 Typ := Etype (Ent); 3933 3934 if Is_Formal (Ent) 3935 and then Is_Suspicious_Type (Typ) 3936 and then not Low_Bound_Tested (Ent) 3937 then 3938 Test_Suspicious_Index; 3939 end if; 3940 end if; 3941 end if; 3942 end Warn_On_Suspicious_Index; 3943 3944 ------------------------------- 3945 -- Warn_On_Suspicious_Update -- 3946 ------------------------------- 3947 3948 procedure Warn_On_Suspicious_Update (N : Node_Id) is 3949 Par : constant Node_Id := Parent (N); 3950 Arg : Node_Id; 3951 3952 begin 3953 -- Only process if warnings activated 3954 3955 if Warn_On_Suspicious_Contract then 3956 if Nkind_In (Par, N_Op_Eq, N_Op_Ne) then 3957 if N = Left_Opnd (Par) then 3958 Arg := Right_Opnd (Par); 3959 else 3960 Arg := Left_Opnd (Par); 3961 end if; 3962 3963 if Same_Object (Prefix (N), Arg) then 3964 if Nkind (Par) = N_Op_Eq then 3965 Error_Msg_N 3966 ("suspicious equality test with modified version of " 3967 & "same object?T?", Par); 3968 else 3969 Error_Msg_N 3970 ("suspicious inequality test with modified version of " 3971 & "same object?T?", Par); 3972 end if; 3973 end if; 3974 end if; 3975 end if; 3976 end Warn_On_Suspicious_Update; 3977 3978 -------------------------------------- 3979 -- Warn_On_Unassigned_Out_Parameter -- 3980 -------------------------------------- 3981 3982 procedure Warn_On_Unassigned_Out_Parameter 3983 (Return_Node : Node_Id; 3984 Scope_Id : Entity_Id) 3985 is 3986 Form : Entity_Id; 3987 Form2 : Entity_Id; 3988 3989 begin 3990 -- Ignore if procedure or return statement does not come from source 3991 3992 if not Comes_From_Source (Scope_Id) 3993 or else not Comes_From_Source (Return_Node) 3994 then 3995 return; 3996 end if; 3997 3998 -- Loop through formals 3999 4000 Form := First_Formal (Scope_Id); 4001 while Present (Form) loop 4002 4003 -- We are only interested in OUT parameters that come from source 4004 -- and are never set in the source, and furthermore only in scalars 4005 -- since non-scalars generate too many false positives. 4006 4007 if Ekind (Form) = E_Out_Parameter 4008 and then Never_Set_In_Source_Check_Spec (Form) 4009 and then Is_Scalar_Type (Etype (Form)) 4010 and then not Present (Unset_Reference (Form)) 4011 then 4012 -- Before we issue the warning, an add ad hoc defence against the 4013 -- most common case of false positives with this warning which is 4014 -- the case where there is a Boolean OUT parameter that has been 4015 -- set, and whose meaning is "ignore the values of the other 4016 -- parameters". We can't of course reliably tell this case at 4017 -- compile time, but the following test kills a lot of false 4018 -- positives, without generating a significant number of false 4019 -- negatives (missed real warnings). 4020 4021 Form2 := First_Formal (Scope_Id); 4022 while Present (Form2) loop 4023 if Ekind (Form2) = E_Out_Parameter 4024 and then Root_Type (Etype (Form2)) = Standard_Boolean 4025 and then not Never_Set_In_Source_Check_Spec (Form2) 4026 then 4027 return; 4028 end if; 4029 4030 Next_Formal (Form2); 4031 end loop; 4032 4033 -- Here all conditions are met, record possible unset reference 4034 4035 Set_Unset_Reference (Form, Return_Node); 4036 end if; 4037 4038 Next_Formal (Form); 4039 end loop; 4040 end Warn_On_Unassigned_Out_Parameter; 4041 4042 --------------------------------- 4043 -- Warn_On_Unreferenced_Entity -- 4044 --------------------------------- 4045 4046 procedure Warn_On_Unreferenced_Entity 4047 (Spec_E : Entity_Id; 4048 Body_E : Entity_Id := Empty) 4049 is 4050 E : Entity_Id := Spec_E; 4051 4052 begin 4053 if not Referenced_Check_Spec (E) 4054 and then not Has_Pragma_Unreferenced_Check_Spec (E) 4055 and then not Warnings_Off_Check_Spec (E) 4056 and then not Has_Junk_Name (Spec_E) 4057 and then not Is_Exported (Spec_E) 4058 then 4059 case Ekind (E) is 4060 when E_Variable => 4061 4062 -- Case of variable that is assigned but not read. We suppress 4063 -- the message if the variable is volatile, has an address 4064 -- clause, is aliased, or is a renaming, or is imported. 4065 4066 if Referenced_As_LHS_Check_Spec (E) 4067 and then No (Address_Clause (E)) 4068 and then not Is_Volatile (E) 4069 then 4070 if Warn_On_Modified_Unread 4071 and then not Is_Imported (E) 4072 and then not Is_Aliased (E) 4073 and then No (Renamed_Object (E)) 4074 then 4075 if not Has_Pragma_Unmodified_Check_Spec (E) then 4076 Error_Msg_N -- CODEFIX 4077 ("?u?variable & is assigned but never read!", E); 4078 end if; 4079 4080 Set_Last_Assignment (E, Empty); 4081 end if; 4082 4083 -- Normal case of neither assigned nor read (exclude variables 4084 -- referenced as out parameters, since we already generated 4085 -- appropriate warnings at the call point in this case). 4086 4087 elsif not Referenced_As_Out_Parameter (E) then 4088 4089 -- We suppress the message for types for which a valid 4090 -- pragma Unreferenced_Objects has been given, otherwise 4091 -- we go ahead and give the message. 4092 4093 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then 4094 4095 -- Distinguish renamed case in message 4096 4097 if Present (Renamed_Object (E)) 4098 and then Comes_From_Source (Renamed_Object (E)) 4099 then 4100 Error_Msg_N -- CODEFIX 4101 ("?u?renamed variable & is not referenced!", E); 4102 else 4103 Error_Msg_N -- CODEFIX 4104 ("?u?variable & is not referenced!", E); 4105 end if; 4106 end if; 4107 end if; 4108 4109 when E_Constant => 4110 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then 4111 if Present (Renamed_Object (E)) 4112 and then Comes_From_Source (Renamed_Object (E)) 4113 then 4114 Error_Msg_N -- CODEFIX 4115 ("?u?renamed constant & is not referenced!", E); 4116 else 4117 Error_Msg_N -- CODEFIX 4118 ("?u?constant & is not referenced!", E); 4119 end if; 4120 end if; 4121 4122 when E_In_Parameter | 4123 E_In_Out_Parameter => 4124 4125 -- Do not emit message for formals of a renaming, because 4126 -- they are never referenced explicitly. 4127 4128 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /= 4129 N_Subprogram_Renaming_Declaration 4130 then 4131 -- Suppress this message for an IN OUT parameter of a 4132 -- non-scalar type, since it is normal to have only an 4133 -- assignment in such a case. 4134 4135 if Ekind (E) = E_In_Parameter 4136 or else not Referenced_As_LHS_Check_Spec (E) 4137 or else Is_Scalar_Type (Etype (E)) 4138 then 4139 if Present (Body_E) then 4140 E := Body_E; 4141 end if; 4142 4143 if not Is_Trivial_Subprogram (Scope (E)) then 4144 Error_Msg_NE -- CODEFIX 4145 ("?u?formal parameter & is not referenced!", 4146 E, Spec_E); 4147 end if; 4148 end if; 4149 end if; 4150 4151 when E_Out_Parameter => 4152 null; 4153 4154 when E_Discriminant => 4155 Error_Msg_N ("?u?discriminant & is not referenced!", E); 4156 4157 when E_Named_Integer | 4158 E_Named_Real => 4159 Error_Msg_N -- CODEFIX 4160 ("?u?named number & is not referenced!", E); 4161 4162 when Formal_Object_Kind => 4163 Error_Msg_N -- CODEFIX 4164 ("?u?formal object & is not referenced!", E); 4165 4166 when E_Enumeration_Literal => 4167 Error_Msg_N -- CODEFIX 4168 ("?u?literal & is not referenced!", E); 4169 4170 when E_Function => 4171 Error_Msg_N -- CODEFIX 4172 ("?u?function & is not referenced!", E); 4173 4174 when E_Procedure => 4175 Error_Msg_N -- CODEFIX 4176 ("?u?procedure & is not referenced!", E); 4177 4178 when E_Package => 4179 Error_Msg_N -- CODEFIX 4180 ("?u?package & is not referenced!", E); 4181 4182 when E_Exception => 4183 Error_Msg_N -- CODEFIX 4184 ("?u?exception & is not referenced!", E); 4185 4186 when E_Label => 4187 Error_Msg_N -- CODEFIX 4188 ("?u?label & is not referenced!", E); 4189 4190 when E_Generic_Procedure => 4191 Error_Msg_N -- CODEFIX 4192 ("?u?generic procedure & is never instantiated!", E); 4193 4194 when E_Generic_Function => 4195 Error_Msg_N -- CODEFIX 4196 ("?u?generic function & is never instantiated!", E); 4197 4198 when Type_Kind => 4199 Error_Msg_N -- CODEFIX 4200 ("?u?type & is not referenced!", E); 4201 4202 when others => 4203 Error_Msg_N -- CODEFIX 4204 ("?u?& is not referenced!", E); 4205 end case; 4206 4207 -- Kill warnings on the entity on which the message has been posted 4208 4209 Set_Warnings_Off (E); 4210 end if; 4211 end Warn_On_Unreferenced_Entity; 4212 4213 -------------------------------- 4214 -- Warn_On_Useless_Assignment -- 4215 -------------------------------- 4216 4217 procedure Warn_On_Useless_Assignment 4218 (Ent : Entity_Id; 4219 N : Node_Id := Empty) 4220 is 4221 P : Node_Id; 4222 X : Node_Id; 4223 4224 function Check_Ref (N : Node_Id) return Traverse_Result; 4225 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to 4226 -- the entity in question is found. 4227 4228 function Test_No_Refs is new Traverse_Func (Check_Ref); 4229 4230 --------------- 4231 -- Check_Ref -- 4232 --------------- 4233 4234 function Check_Ref (N : Node_Id) return Traverse_Result is 4235 begin 4236 -- Check reference to our identifier. We use name equality here 4237 -- because the exception handlers have not yet been analyzed. This 4238 -- is not quite right, but it really does not matter that we fail 4239 -- to output the warning in some obscure cases of name clashes. 4240 4241 if Nkind (N) = N_Identifier and then Chars (N) = Chars (Ent) then 4242 return Abandon; 4243 else 4244 return OK; 4245 end if; 4246 end Check_Ref; 4247 4248 -- Start of processing for Warn_On_Useless_Assignment 4249 4250 begin 4251 -- Check if this is a case we want to warn on, a scalar or access 4252 -- variable with the last assignment field set, with warnings enabled, 4253 -- and which is not imported or exported. We also check that it is OK 4254 -- to capture the value. We are not going to capture any value, but 4255 -- the warning message depends on the same kind of conditions. 4256 4257 if Is_Assignable (Ent) 4258 and then not Is_Return_Object (Ent) 4259 and then Present (Last_Assignment (Ent)) 4260 and then not Is_Imported (Ent) 4261 and then not Is_Exported (Ent) 4262 and then Safe_To_Capture_Value (N, Ent) 4263 and then not Has_Pragma_Unreferenced_Check_Spec (Ent) 4264 and then not Has_Junk_Name (Ent) 4265 then 4266 -- Before we issue the message, check covering exception handlers. 4267 -- Search up tree for enclosing statement sequences and handlers. 4268 4269 P := Parent (Last_Assignment (Ent)); 4270 while Present (P) loop 4271 4272 -- Something is really wrong if we don't find a handled statement 4273 -- sequence, so just suppress the warning. 4274 4275 if No (P) then 4276 Set_Last_Assignment (Ent, Empty); 4277 return; 4278 4279 -- When we hit a package/subprogram body, issue warning and exit 4280 4281 elsif Nkind (P) = N_Subprogram_Body 4282 or else Nkind (P) = N_Package_Body 4283 then 4284 -- Case of assigned value never referenced 4285 4286 if No (N) then 4287 declare 4288 LA : constant Node_Id := Last_Assignment (Ent); 4289 4290 begin 4291 -- Don't give this for OUT and IN OUT formals, since 4292 -- clearly caller may reference the assigned value. Also 4293 -- never give such warnings for internal variables. 4294 4295 if Ekind (Ent) = E_Variable 4296 and then not Is_Internal_Name (Chars (Ent)) 4297 then 4298 -- Give appropriate message, distinguishing between 4299 -- assignment statements and out parameters. 4300 4301 if Nkind_In (Parent (LA), N_Procedure_Call_Statement, 4302 N_Parameter_Association) 4303 then 4304 Error_Msg_NE 4305 ("?m?& modified by call, but value never " 4306 & "referenced", LA, Ent); 4307 4308 else 4309 Error_Msg_NE -- CODEFIX 4310 ("?m?useless assignment to&, value never " 4311 & "referenced!", LA, Ent); 4312 end if; 4313 end if; 4314 end; 4315 4316 -- Case of assigned value overwritten 4317 4318 else 4319 declare 4320 LA : constant Node_Id := Last_Assignment (Ent); 4321 4322 begin 4323 Error_Msg_Sloc := Sloc (N); 4324 4325 -- Give appropriate message, distinguishing between 4326 -- assignment statements and out parameters. 4327 4328 if Nkind_In (Parent (LA), N_Procedure_Call_Statement, 4329 N_Parameter_Association) 4330 then 4331 Error_Msg_NE 4332 ("?m?& modified by call, but value overwritten #!", 4333 LA, Ent); 4334 else 4335 Error_Msg_NE -- CODEFIX 4336 ("?m?useless assignment to&, value overwritten #!", 4337 LA, Ent); 4338 end if; 4339 end; 4340 end if; 4341 4342 -- Clear last assignment indication and we are done 4343 4344 Set_Last_Assignment (Ent, Empty); 4345 return; 4346 4347 -- Enclosing handled sequence of statements 4348 4349 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then 4350 4351 -- Check exception handlers present 4352 4353 if Present (Exception_Handlers (P)) then 4354 4355 -- If we are not at the top level, we regard an inner 4356 -- exception handler as a decisive indicator that we should 4357 -- not generate the warning, since the variable in question 4358 -- may be accessed after an exception in the outer block. 4359 4360 if Nkind (Parent (P)) /= N_Subprogram_Body 4361 and then Nkind (Parent (P)) /= N_Package_Body 4362 then 4363 Set_Last_Assignment (Ent, Empty); 4364 return; 4365 4366 -- Otherwise we are at the outer level. An exception 4367 -- handler is significant only if it references the 4368 -- variable in question, or if the entity in question 4369 -- is an OUT or IN OUT parameter, which which case 4370 -- the caller can reference it after the exception 4371 -- handler completes. 4372 4373 else 4374 if Is_Formal (Ent) then 4375 Set_Last_Assignment (Ent, Empty); 4376 return; 4377 4378 else 4379 X := First (Exception_Handlers (P)); 4380 while Present (X) loop 4381 if Test_No_Refs (X) = Abandon then 4382 Set_Last_Assignment (Ent, Empty); 4383 return; 4384 end if; 4385 4386 X := Next (X); 4387 end loop; 4388 end if; 4389 end if; 4390 end if; 4391 end if; 4392 4393 P := Parent (P); 4394 end loop; 4395 end if; 4396 end Warn_On_Useless_Assignment; 4397 4398 --------------------------------- 4399 -- Warn_On_Useless_Assignments -- 4400 --------------------------------- 4401 4402 procedure Warn_On_Useless_Assignments (E : Entity_Id) is 4403 Ent : Entity_Id; 4404 4405 begin 4406 Process_Deferred_References; 4407 4408 if Warn_On_Modified_Unread 4409 and then In_Extended_Main_Source_Unit (E) 4410 then 4411 Ent := First_Entity (E); 4412 while Present (Ent) loop 4413 Warn_On_Useless_Assignment (Ent); 4414 Next_Entity (Ent); 4415 end loop; 4416 end if; 4417 end Warn_On_Useless_Assignments; 4418 4419 ----------------------------- 4420 -- Warnings_Off_Check_Spec -- 4421 ----------------------------- 4422 4423 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is 4424 begin 4425 if Is_Formal (E) and then Present (Spec_Entity (E)) then 4426 4427 -- Note: use of OR here instead of OR ELSE is deliberate, we want 4428 -- to mess with flags on both entities. 4429 4430 return Has_Warnings_Off (E) 4431 or 4432 Has_Warnings_Off (Spec_Entity (E)); 4433 4434 else 4435 return Has_Warnings_Off (E); 4436 end if; 4437 end Warnings_Off_Check_Spec; 4438 4439end Sem_Warn; 4440