1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2015, Free Software Foundation, Inc. --
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. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Debug; use Debug;
28 with Einfo; use Einfo;
29 with Errout; use Errout;
30 with Exp_Code; use Exp_Code;
31 with Fname; use Fname;
33 with Lib.Xref; use Lib.Xref;
34 with Namet; use Namet;
35 with Nlists; use Nlists;
37 with Par_SCO; use Par_SCO;
38 with Rtsfind; use Rtsfind;
40 with Sem_Ch8; use Sem_Ch8;
41 with Sem_Aux; use Sem_Aux;
42 with Sem_Eval; use Sem_Eval;
43 with Sem_Prag; use Sem_Prag;
44 with Sem_Util; use Sem_Util;
45 with Sinfo; use Sinfo;
46 with Sinput; use Sinput;
47 with Snames; use Snames;
48 with Stand; use Stand;
49 with Stringt; use Stringt;
50 with Uintp; use Uintp;
52 package body Sem_Warn is
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.
58 package Unreferenced_Entities is new Table.Table (
59 Table_Component_Type => Entity_Id,
60 Table_Index_Type => Nat,
62 Table_Initial => Alloc.Unreferenced_Entities_Initial,
63 Table_Increment => Alloc.Unreferenced_Entities_Increment,
64 Table_Name => "Unreferenced_Entities");
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.
76 package In_Out_Warnings is new Table.Table (
77 Table_Component_Type => Entity_Id,
78 Table_Index_Type => Nat,
80 Table_Initial => Alloc.In_Out_Warnings_Initial,
81 Table_Increment => Alloc.In_Out_Warnings_Increment,
82 Table_Name => "In_Out_Warnings");
84 --------------------------------------------------------
85 -- Handling of Warnings Off, Unmodified, Unreferenced --
86 --------------------------------------------------------
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.
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.
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:
99 -- if not Has_Warnings_Off (E)
100 -- and then some-other-predicate-on-E then ..
102 -- Instead the following is preferred
104 -- if some-other-predicate-on-E
105 -- and then Has_Warnings_Off (E)
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.
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).
117 -----------------------
118 -- Local Subprograms --
119 -----------------------
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.
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.
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).
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).
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).
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.
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).
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).
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).
175 procedure Warn_On_Unreferenced_Entity
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.
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.
187 --------------------------
188 -- Check_Code_Statement --
189 --------------------------
191 procedure Check_Code_Statement (N : Node_Id) is
193 -- If volatile, nothing to worry about
195 if Is_Asm_Volatile (N) then
199 -- Warn if no input or no output
201 Setup_Asm_Inputs (N);
203 if No (Asm_Input_Value) then
205 ("??code statement with no inputs should usually be Volatile!", N);
209 Setup_Asm_Outputs (N);
211 if No (Asm_Output_Variable) then
213 ("??code statement with no outputs should usually be Volatile!", N);
216 end Check_Code_Statement;
218 ---------------------------------
219 -- Check_Infinite_Loop_Warning --
220 ---------------------------------
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.
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
230 Ref : Node_Id := Empty;
231 -- Reference in Expression to variable that might not be modified
232 -- in loop, indicating a possible infinite loop.
234 Var : Entity_Id := Empty;
235 -- Corresponding entity (entity of Ref)
237 Function_Call_Found : Boolean := False;
238 -- True if Find_Var found a function call in the condition
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.
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.
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.
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.
263 function No_Ref_Found is new Traverse_Func (Test_Ref);
264 -- Function to traverse body of procedure. Returns Abandon if matching
271 procedure Find_Var (N : Node_Id) is
273 -- Condition is a direct variable reference
275 if Is_Entity_Name (N) then
279 -- Case of condition is a comparison with compile time known value
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));
285 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
286 Find_Var (Right_Opnd (N));
288 -- Ignore any other comparison
294 -- If condition is a negation, check its operand
296 elsif Nkind (N) = N_Op_Not then
297 Find_Var (Right_Opnd (N));
299 -- Case of condition is function call
301 elsif Nkind (N) = N_Function_Call then
303 Function_Call_Found := True;
305 -- Forget it if function name is not entity, who knows what
306 -- we might be calling?
308 if not Is_Entity_Name (Name (N)) then
311 -- Forget it if function name is suspicious. A strange test
312 -- but warning generation is in the heuristics business.
314 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
317 -- Forget it if warnings are suppressed on function entity
319 elsif Has_Warnings_Off (Entity (Name (N))) then
323 -- OK, see if we have one argument
326 PA : constant List_Id := Parameter_Associations (N);
329 -- One argument, so check the argument
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)));
335 Find_Var (First (PA));
345 -- Any other kind of node is not something we warn for
352 ---------------------
353 -- Has_Indirection --
354 ---------------------
356 function Has_Indirection (T : Entity_Id) return Boolean is
361 if Is_Access_Type (T) then
364 elsif Is_Private_Type (T)
365 and then Present (Full_View (T))
366 and then Is_Access_Type (Full_View (T))
370 elsif Is_Record_Type (T) then
373 elsif Is_Private_Type (T)
374 and then Present (Full_View (T))
375 and then Is_Record_Type (Full_View (T))
377 Rec := Full_View (T);
382 Comp := First_Component (Rec);
383 while Present (Comp) loop
384 if Is_Access_Type (Etype (Comp))
385 or else Is_Descendant_Of_Address (Etype (Comp))
390 Next_Component (Comp);
396 ---------------------------------
397 -- Is_Suspicious_Function_Name --
398 ---------------------------------
400 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
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.
407 -----------------------
408 -- Substring_Present --
409 -----------------------
411 function Substring_Present (S : String) return Boolean is
412 Len : constant Natural := S'Length;
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')
420 or else Name_Buffer (J + Len) not in 'a' .. 'z')
427 end Substring_Present;
429 -- Start of processing for Is_Suspicious_Function_Name
433 while Present (S) and then S /= Standard_Standard loop
434 Get_Name_String (Chars (S));
436 if Substring_Present ("io")
437 or else Substring_Present ("file")
438 or else Substring_Present ("network")
447 end Is_Suspicious_Function_Name;
453 function Test_Ref (N : Node_Id) return Traverse_Result is
455 -- Waste of time to look at the expression we are testing
457 if N = Expression then
460 -- Direct reference to variable in question
462 elsif Is_Entity_Name (N)
463 and then Present (Entity (N))
464 and then Entity (N) = Var
466 -- If this is an lvalue, then definitely abandon, since
467 -- this could be a direct modification of the variable.
469 if May_Be_Lvalue (N) then
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.
482 if Function_Call_Found then
490 exit when P = Loop_Statement;
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.
499 or else Nkind (P) = N_Procedure_Call_Statement
507 -- Reference to variable renaming variable in question
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)
519 -- Call to subprogram
521 elsif Nkind (N) in N_Subprogram_Call then
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.
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))
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.
542 Actual := First_Actual (N);
543 while Present (Actual) loop
544 if Is_Access_Subprogram_Type (Etype (Actual)) then
547 Next_Actual (Actual);
552 -- Declaration of the variable in question
554 elsif Nkind (N) = N_Object_Declaration
555 and then Defining_Identifier (N) = Var
560 -- All OK, continue scan
565 -- Start of processing for Check_Infinite_Loop_Warning
568 -- Skip processing if debug flag gnatd.w is set
570 if Debug_Flag_Dot_W then
574 -- Deal with Iteration scheme present
577 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
580 if Present (Iter) then
584 if Present (Condition (Iter)) then
586 -- Skip processing for while iteration with conditions actions,
587 -- since they make it too complicated to get the warning right.
589 if Present (Condition_Actions (Iter)) then
593 -- Capture WHILE condition
595 Expression := Condition (Iter);
597 -- For iteration, do not process, since loop will always terminate
599 elsif Present (Loop_Parameter_Specification (Iter)) then
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).
610 Ident : constant Node_Id := Identifier (Loop_Statement);
614 -- If we don't have a proper chain set, ignore call entirely. This
615 -- happens because of previous errors.
617 if No (Entity (Ident))
618 or else Ekind (Entity (Ident)) /= E_Loop
620 Check_Error_Detected;
624 -- Otherwise prepare to scan list of EXIT statements
626 Exit_Stmt := First_Exit_Statement (Entity (Ident));
627 while Present (Exit_Stmt) loop
629 -- Check for EXIT WHEN
631 if Present (Condition (Exit_Stmt)) then
633 -- Quit processing if EXIT WHEN in WHILE loop, or more than
634 -- one EXIT WHEN statement present in the loop.
636 if Present (Expression) then
639 -- Otherwise capture condition from EXIT WHEN statement
642 Expression := Condition (Exit_Stmt);
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.
649 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then
653 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
657 -- Return if no condition to test
659 if No (Expression) then
663 -- Initial conditions met, see if condition is of right form
665 Find_Var (Expression);
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
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
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.
685 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
688 -- Same sort of thing for volatile variable, might be modified by
689 -- some other task or by the operating system in some way.
691 elsif Is_Volatile (Var) then
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).
700 Fstm : constant Node_Id :=
701 Original_Node (First (Statements (Loop_Statement)));
703 if Nkind (Fstm) = N_Delay_Relative_Statement
704 or else Nkind (Fstm) = N_Delay_Until_Statement
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
713 if No_Ref_Found (Loop_Statement) = OK then
715 ("??variable& is not modified in loop body!", Ref, Var);
717 ("\??possible infinite loop!", Ref);
719 end Check_Infinite_Loop_Warning;
721 ----------------------------
722 -- Check_Low_Bound_Tested --
723 ----------------------------
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.
731 --------------------------------
732 -- Check_Low_Bound_Tested_For --
733 --------------------------------
735 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id) is
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)))
743 Set_Low_Bound_Tested (Entity (Prefix (Opnd)));
745 end Check_Low_Bound_Tested_For;
747 -- Start of processing for Check_Low_Bound_Tested
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));
754 end Check_Low_Bound_Tested;
756 ----------------------
757 -- Check_References --
758 ----------------------
760 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
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.
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.
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.
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.
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.
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.
805 Accept_Statement : Node_Id) return Entity_Id
807 Body_Param : Node_Id;
811 -- Loop to find matching parameter in accept statement
813 Body_Param := First (Parameter_Specifications (Accept_Statement));
814 while Present (Body_Param) loop
815 Body_E := Defining_Identifier (Body_Param);
817 if Chars (Body_E) = Chars (E) then
824 -- Should never fall through, should always find a match
829 ---------------------------------
830 -- May_Need_Initialized_Actual --
831 ---------------------------------
833 procedure May_Need_Initialized_Actual (Ent : Entity_Id) is
834 T : constant Entity_Id := Etype (Ent);
835 Par : constant Node_Id := Parent (T);
838 if not Is_Generic_Type (T) then
841 elsif (Nkind (Par)) = N_Private_Extension_Declaration then
843 -- We only indicate the first such variable in the generic.
845 if No (Uninitialized_Variable (Par)) then
846 Set_Uninitialized_Variable (Par, Ent);
849 elsif (Nkind (Par)) = N_Formal_Type_Declaration
850 and then Nkind (Formal_Type_Definition (Par)) =
851 N_Formal_Private_Type_Definition
853 if No (Uninitialized_Variable (Formal_Type_Definition (Par))) then
854 Set_Uninitialized_Variable (Formal_Type_Definition (Par), Ent);
857 end May_Need_Initialized_Actual;
859 ----------------------
860 -- Missing_Subunits --
861 ----------------------
863 function Missing_Subunits return Boolean is
867 if not Unloaded_Subunits then
869 -- Normal compilation, all subunits are present
873 elsif E /= Main_Unit_Entity then
875 -- No warnings on a stub that is not the main unit
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
883 -- No warnings if the proper body contains nested stubs
885 if Nkind (D) in N_Body_Stub then
895 -- Missing stubs elsewhere
899 end Missing_Subunits;
901 ----------------------------
902 -- Output_Reference_Error --
903 ----------------------------
905 procedure Output_Reference_Error (M : String) is
907 -- Never issue messages for internal names or renamings
909 if Is_Internal_Name (Chars (E1))
910 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
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.
920 if Ekind (E1) = E_In_Out_Parameter
921 and then not Check_Unreferenced_Formals
926 -- Other than accept case, post error on defining identifier
931 -- Accept case, find body formal to post the message
934 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
937 end Output_Reference_Error;
939 ----------------------------
940 -- Publicly_Referenceable --
941 ----------------------------
943 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
948 -- A formal parameter is never referenceable outside the body of its
949 -- subprogram or entry.
951 if Is_Formal (Ent) then
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.
964 -- If we get to top of tree, then publicly referenceable
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.
975 -- Note that generic formal parameters are themselves not
976 -- publicly referenceable in an instance, and warnings on them
979 when N_Generic_Package_Declaration =>
981 not Is_List_Member (Prev)
982 or else List_Containing (Prev) /=
983 Generic_Formal_Declarations (P);
985 -- Similarly, the generic formals of a generic subprogram are
988 when N_Generic_Subprogram_Declaration =>
989 if Is_List_Member (Prev)
990 and then List_Containing (Prev) =
991 Generic_Formal_Declarations (P)
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.
1003 when N_Subprogram_Body =>
1004 if Ent /= Defining_Entity (P) then
1010 -- If we reach any other body, definitely not referenceable
1012 when N_Package_Body |
1020 -- For all other cases, keep looking up tree
1027 end Publicly_Referenceable;
1029 ---------------------
1030 -- Warnings_Off_E1 --
1031 ---------------------
1033 function Warnings_Off_E1 return Boolean is
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;
1040 -- Start of processing for Check_References
1043 Process_Deferred_References;
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).
1049 if Warning_Mode = Suppress or else Serious_Errors_Detected /= 0 then
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).
1057 if Missing_Subunits then
1061 -- Otherwise loop through entities, looking for suspicious stuff
1063 E1 := First_Entity (E);
1064 while Present (E1) loop
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.
1072 if Comes_From_Source (E1)
1073 and then Instantiation_Location (Sloc (E1)) = No_Location
1075 -- We are interested in variables and out/in-out parameters, but
1076 -- we exclude protected types, too complicated to worry about.
1078 if Ekind (E1) = E_Variable
1080 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1081 and then not Is_Protected_Type (Current_Scope))
1083 -- If the formal has a class-wide type, retrieve its type
1084 -- because checks below depend on its private nature.
1086 if Is_Class_Wide_Type (E1T) then
1090 -- Case of an unassigned variable
1092 -- First gather any Unset_Reference indication for E1. In the
1093 -- case of a parameter, it is the Spec_Entity that is relevant.
1095 if Ekind (E1) = E_Out_Parameter
1096 and then Present (Spec_Entity (E1))
1098 UR := Unset_Reference (Spec_Entity (E1));
1100 UR := Unset_Reference (E1);
1103 -- Special processing for access types
1105 if Present (UR) and then Is_Access_Type (E1T) then
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).
1115 if not Warnings_Off_E1 then
1116 Error_Msg_NE ("??& may be null!", UR, E1);
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
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.
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)
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). Instead we suggest
1141 -- using pragma Export (can't be Import because of the
1144 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1145 and then not Is_Imported (E1)
1148 ("?k?& is not modified, " &
1149 "consider pragma Export for volatile variable!",
1152 -- Another special case, Exception_Occurrence, this catches
1153 -- the case of exception choice (and a bit more too, but not
1154 -- worth doing more investigation here).
1156 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1159 -- Here we give the warning if referenced and no pragma
1160 -- Unreferenced or Unmodified is present.
1165 if Ekind (E1) = E_Variable then
1166 if Referenced_Check_Spec (E1)
1167 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1168 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1170 if not Warnings_Off_E1
1171 and then not Has_Junk_Name (E1)
1173 Error_Msg_N -- CODEFIX
1174 ("?k?& is not modified, "
1175 & "could be declared constant!",
1182 -- Other cases of a variable or parameter never set in source
1184 elsif Never_Set_In_Source_Check_Spec (E1)
1186 -- No warning if warning for this case turned off
1188 and then Warn_On_No_Value_Assigned
1190 -- No warning if address taken somewhere
1192 and then not Address_Taken (E1)
1194 -- No warning if explicit initial value
1196 and then not Has_Initial_Value (E1)
1198 -- No warning for generic package spec entities, since we
1199 -- might set them in a child unit or something like that
1201 and then not Generic_Package_Spec_Entity (E1)
1203 -- No warning if fully initialized type, except that for
1204 -- this purpose we do not consider access types to qualify
1205 -- as fully initialized types (relying on an access type
1206 -- variable being null when it is never set is a bit odd).
1208 -- Also we generate warning for an out parameter that is
1209 -- never referenced, since again it seems odd to rely on
1210 -- default initialization to set an out parameter value.
1212 and then (Is_Access_Type (E1T)
1213 or else Ekind (E1) = E_Out_Parameter
1214 or else not Is_Fully_Initialized_Type (E1T))
1216 -- Do not output complaint about never being assigned a
1217 -- value if a pragma Unmodified applies to the variable
1218 -- we are examining, or if it is a parameter, if there is
1219 -- a pragma Unreferenced for the corresponding spec, or
1220 -- if the type is marked as having unreferenced objects.
1221 -- The last is a little peculiar, but better too few than
1222 -- too many warnings in this situation.
1224 if Has_Pragma_Unreferenced_Objects (E1T)
1225 or else Has_Pragma_Unmodified_Check_Spec (E1)
1229 -- IN OUT parameter case where parameter is referenced. We
1230 -- separate this out, since this is the case where we delay
1231 -- output of the warning until more information is available
1232 -- (about use in an instantiation or address being taken).
1234 elsif Ekind (E1) = E_In_Out_Parameter
1235 and then Referenced_Check_Spec (E1)
1237 -- Suppress warning if private type, and the procedure
1238 -- has a separate declaration in a different unit. This
1239 -- is the case where the client of a package sees only
1240 -- the private type, and it may be quite reasonable
1241 -- for the logical view to be IN OUT, even if the
1242 -- implementation ends up using access types or some
1243 -- other method to achieve the local effect of a
1244 -- modification. On the other hand if the spec and body
1245 -- are in the same unit, we are in the package body and
1246 -- there we have less excuse for a junk IN OUT parameter.
1248 if Has_Private_Declaration (E1T)
1249 and then Present (Spec_Entity (E1))
1250 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1254 -- Suppress warning for any parameter of a dispatching
1255 -- operation, since it is quite reasonable to have an
1256 -- operation that is overridden, and for some subclasses
1257 -- needs the formal to be IN OUT and for others happens
1258 -- not to assign it.
1260 elsif Is_Dispatching_Operation
1261 (Scope (Goto_Spec_Entity (E1)))
1265 -- Suppress warning if composite type contains any access
1266 -- component, since the logical effect of modifying a
1267 -- parameter may be achieved by modifying a referenced
1270 elsif Is_Composite_Type (E1T)
1271 and then Has_Access_Values (E1T)
1275 -- Suppress warning on formals of an entry body. All
1276 -- references are attached to the formal in the entry
1277 -- declaration, which are marked Is_Entry_Formal.
1279 elsif Ekind (Scope (E1)) = E_Entry
1280 and then not Is_Entry_Formal (E1)
1284 -- OK, looks like warning for an IN OUT parameter that
1285 -- could be IN makes sense, but we delay the output of
1286 -- the warning, pending possibly finding out later on
1287 -- that the associated subprogram is used as a generic
1288 -- actual, or its address/access is taken. In these two
1289 -- cases, we suppress the warning because the context may
1290 -- force use of IN OUT, even if in this particular case
1291 -- the formal is not modified.
1294 -- Suppress the warnings for a junk name
1296 if not Has_Junk_Name (E1) then
1297 In_Out_Warnings.Append (E1);
1301 -- Other cases of formals
1303 elsif Is_Formal (E1) then
1304 if not Is_Trivial_Subprogram (Scope (E1)) then
1305 if Referenced_Check_Spec (E1) then
1306 if not Has_Pragma_Unmodified_Check_Spec (E1)
1307 and then not Warnings_Off_E1
1308 and then not Has_Junk_Name (E1)
1310 Output_Reference_Error
1311 ("?f?formal parameter& is read but "
1312 & "never assigned!");
1315 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1316 and then not Warnings_Off_E1
1317 and then not Has_Junk_Name (E1)
1319 Output_Reference_Error
1320 ("?f?formal parameter& is not referenced!");
1327 if Referenced (E1) then
1328 if not Has_Unmodified (E1)
1329 and then not Warnings_Off_E1
1330 and then not Has_Junk_Name (E1)
1332 Output_Reference_Error
1333 ("?v?variable& is read but never assigned!");
1334 May_Need_Initialized_Actual (E1);
1337 elsif not Has_Unreferenced (E1)
1338 and then not Warnings_Off_E1
1339 and then not Has_Junk_Name (E1)
1341 Output_Reference_Error -- CODEFIX
1342 ("?v?variable& is never read and never assigned!");
1345 -- Deal with special case where this variable is hidden
1346 -- by a loop variable.
1348 if Ekind (E1) = E_Variable
1349 and then Present (Hiding_Loop_Variable (E1))
1350 and then not Warnings_Off_E1
1353 ("?v?for loop implicitly declares loop variable!",
1354 Hiding_Loop_Variable (E1));
1356 Error_Msg_Sloc := Sloc (E1);
1358 ("\?v?declaration hides & declared#!",
1359 Hiding_Loop_Variable (E1));
1366 -- Check for unset reference
1368 if Warn_On_No_Value_Assigned and then Present (UR) then
1370 -- For other than access type, go back to original node to
1371 -- deal with case where original unset reference has been
1372 -- rewritten during expansion.
1374 -- In some cases, the original node may be a type conversion
1375 -- or qualification, and in this case we want the object
1378 UR := Original_Node (UR);
1379 while Nkind (UR) = N_Type_Conversion
1380 or else Nkind (UR) = N_Qualified_Expression
1381 or else Nkind (UR) = N_Expression_With_Actions
1383 UR := Expression (UR);
1386 -- Don't issue warning if appearing inside Initial_Condition
1387 -- pragma or aspect, since that expression is not evaluated
1388 -- at the point where it occurs in the source.
1390 if In_Pragma_Expression (UR, Name_Initial_Condition) then
1394 -- Here we issue the warning, all checks completed
1396 -- If we have a return statement, this was a case of an OUT
1397 -- parameter not being set at the time of the return. (Note:
1398 -- it can't be N_Extended_Return_Statement, because those
1399 -- are only for functions, and functions do not allow OUT
1402 if not Is_Trivial_Subprogram (Scope (E1)) then
1403 if Nkind (UR) = N_Simple_Return_Statement
1404 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1406 if not Warnings_Off_E1
1407 and then not Has_Junk_Name (E1)
1410 ("?v?OUT parameter& not set before return",
1414 -- If the unset reference is a selected component
1415 -- prefix from source, mention the component as well.
1416 -- If the selected component comes from expansion, all
1417 -- we know is that the entity is not fully initialized
1418 -- at the point of the reference. Locate a random
1419 -- uninitialized component to get a better message.
1421 elsif Nkind (Parent (UR)) = N_Selected_Component then
1422 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1424 if not Comes_From_Source (Parent (UR)) then
1429 Comp := First_Entity (E1T);
1430 while Present (Comp) loop
1431 if Ekind (Comp) = E_Component
1432 and then Nkind (Parent (Comp)) =
1433 N_Component_Declaration
1434 and then No (Expression (Parent (Comp)))
1436 Error_Msg_Node_2 := Comp;
1445 -- Issue proper warning. This is a case of referencing
1446 -- a variable before it has been explicitly assigned.
1447 -- For access types, UR was only set for dereferences,
1448 -- so the issue is that the value may be null.
1450 if not Is_Trivial_Subprogram (Scope (E1)) then
1451 if not Warnings_Off_E1 then
1452 if Is_Access_Type (Etype (Parent (UR))) then
1453 Error_Msg_N ("??`&.&` may be null!", UR);
1456 ("??`&.&` may be referenced before "
1457 & "it has a value!", UR);
1462 -- All other cases of unset reference active
1464 elsif not Warnings_Off_E1 then
1466 ("??& may be referenced before it has a value!", UR);
1475 -- Then check for unreferenced entities. Note that we are only
1476 -- interested in entities whose Referenced flag is not set.
1478 if not Referenced_Check_Spec (E1)
1480 -- If Referenced_As_LHS is set, then that's still interesting
1481 -- (potential "assigned but never read" case), but not if we
1482 -- have pragma Unreferenced, which cancels this warning.
1484 and then (not Referenced_As_LHS_Check_Spec (E1)
1485 or else not Has_Unreferenced (E1))
1487 -- Check that warnings on unreferenced entities are enabled
1490 ((Check_Unreferenced and then not Is_Formal (E1))
1492 -- Case of warning on unreferenced formal
1494 or else (Check_Unreferenced_Formals and then Is_Formal (E1))
1496 -- Case of warning on unread variables modified by an
1497 -- assignment, or an OUT parameter if it is the only one.
1499 or else (Warn_On_Modified_Unread
1500 and then Referenced_As_LHS_Check_Spec (E1))
1502 -- Case of warning on any unread OUT parameter (note such
1503 -- indications are only set if the appropriate warning
1504 -- options were set, so no need to recheck here.)
1506 or else Referenced_As_Out_Parameter_Check_Spec (E1))
1508 -- All other entities, including local packages that cannot be
1509 -- referenced from elsewhere, including those declared within a
1512 and then (Is_Object (E1)
1513 or else Is_Type (E1)
1514 or else Ekind (E1) = E_Label
1515 or else Ekind_In (E1, E_Exception,
1518 or else Is_Overloadable (E1)
1520 -- Package case, if the main unit is a package spec
1521 -- or generic package spec, then there may be a
1522 -- corresponding body that references this package
1523 -- in some other file. Otherwise we can be sure
1524 -- that there is no other reference.
1527 (Ekind (E1) = E_Package
1529 not Is_Package_Or_Generic_Package
1530 (Cunit_Entity (Current_Sem_Unit))))
1532 -- Exclude instantiations, since there is no reason why every
1533 -- entity in an instantiation should be referenced.
1535 and then Instantiation_Location (Sloc (E1)) = No_Location
1537 -- Exclude formal parameters from bodies if the corresponding
1538 -- spec entity has been referenced in the case where there is
1541 and then not (Is_Formal (E1)
1542 and then Ekind (Scope (E1)) = E_Subprogram_Body
1543 and then Present (Spec_Entity (E1))
1544 and then Referenced (Spec_Entity (E1)))
1546 -- Consider private type referenced if full view is referenced.
1547 -- If there is not full view, this is a generic type on which
1548 -- warnings are also useful.
1551 not (Is_Private_Type (E1)
1552 and then Present (Full_View (E1))
1553 and then Referenced (Full_View (E1)))
1555 -- Don't worry about full view, only about private type
1557 and then not Has_Private_Declaration (E1)
1559 -- Eliminate dispatching operations from consideration, we
1560 -- cannot tell if these are referenced or not in any easy
1561 -- manner (note this also catches Adjust/Finalize/Initialize).
1563 and then not Is_Dispatching_Operation (E1)
1565 -- Check entity that can be publicly referenced (we do not give
1566 -- messages for such entities, since there could be other
1567 -- units, not involved in this compilation, that contain
1568 -- relevant references.
1570 and then not Publicly_Referenceable (E1)
1572 -- Class wide types are marked as source entities, but they are
1573 -- not really source entities, and are always created, so we do
1574 -- not care if they are not referenced.
1576 and then Ekind (E1) /= E_Class_Wide_Type
1578 -- Objects other than parameters of task types are allowed to
1579 -- be non-referenced, since they start up tasks.
1581 and then ((Ekind (E1) /= E_Variable
1582 and then Ekind (E1) /= E_Constant
1583 and then Ekind (E1) /= E_Component)
1584 or else not Is_Task_Type (E1T))
1586 -- For subunits, only place warnings on the main unit itself,
1587 -- since parent units are not completely compiled.
1589 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1590 or else Get_Source_Unit (E1) = Main_Unit)
1592 -- No warning on a return object, because these are often
1593 -- created with a single expression and an implicit return.
1594 -- If the object is a variable there will be a warning
1595 -- indicating that it could be declared constant.
1598 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1600 -- Suppress warnings in internal units if not in -gnatg mode
1601 -- (these would be junk warnings for an applications program,
1602 -- since they refer to problems in internal units).
1605 or else not Is_Internal_File_Name
1606 (Unit_File_Name (Get_Source_Unit (E1)))
1608 -- We do not immediately flag the error. This is because we
1609 -- have not expanded generic bodies yet, and they may have
1610 -- the missing reference. So instead we park the entity on a
1611 -- list, for later processing. However for the case of an
1612 -- accept statement we want to output messages now, since
1613 -- we know we already have all information at hand, and we
1614 -- also want to have separate warnings for each accept
1615 -- statement for the same entry.
1617 if Present (Anod) then
1618 pragma Assert (Is_Formal (E1));
1620 -- The unreferenced entity is E1, but post the warning
1621 -- on the body entity for this accept statement.
1623 if not Warnings_Off_E1 then
1624 Warn_On_Unreferenced_Entity
1625 (E1, Body_Formal (E1, Accept_Statement => Anod));
1628 elsif not Warnings_Off_E1
1629 and then not Has_Junk_Name (E1)
1631 Unreferenced_Entities.Append (E1);
1635 -- Generic units are referenced in the generic body, but if they
1636 -- are not public and never instantiated we want to force a
1637 -- warning on them. We treat them as redundant constructs to
1640 elsif Is_Generic_Subprogram (E1)
1641 and then not Is_Instantiated (E1)
1642 and then not Publicly_Referenceable (E1)
1643 and then Instantiation_Depth (Sloc (E1)) = 0
1644 and then Warn_On_Redundant_Constructs
1646 if not Warnings_Off_E1 and then not Has_Junk_Name (E1) then
1647 Unreferenced_Entities.Append (E1);
1649 -- Force warning on entity
1651 Set_Referenced (E1, False);
1656 -- Recurse into nested package or block. Do not recurse into a formal
1657 -- package, because the corresponding body is not analyzed.
1660 if (Is_Package_Or_Generic_Package (E1)
1661 and then Nkind (Parent (E1)) = N_Package_Specification
1663 Nkind (Original_Node (Unit_Declaration_Node (E1))) /=
1664 N_Formal_Package_Declaration)
1666 or else Ekind (E1) = E_Block
1668 Check_References (E1);
1673 end Check_References;
1675 ---------------------------
1676 -- Check_Unset_Reference --
1677 ---------------------------
1679 procedure Check_Unset_Reference (N : Node_Id) is
1680 Typ : constant Entity_Id := Etype (N);
1682 function Is_OK_Fully_Initialized return Boolean;
1683 -- This function returns true if the given node N is fully initialized
1684 -- so that the reference is safe as far as this routine is concerned.
1685 -- Safe generally means that the type of N is a fully initialized type.
1686 -- The one special case is that for access types, which are always fully
1687 -- initialized, we don't consider a dereference OK since it will surely
1688 -- be dereferencing a null value, which won't do.
1690 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1691 -- Used to test indexed or selected component or slice to see if the
1692 -- evaluation of the prefix depends on a dereference, and if so, returns
1693 -- True, in which case we always check the prefix, even if we know that
1694 -- the referenced component is initialized. Pref is the prefix to test.
1696 -----------------------------
1697 -- Is_OK_Fully_Initialized --
1698 -----------------------------
1700 function Is_OK_Fully_Initialized return Boolean is
1702 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1705 -- If a type has Default_Initial_Condition set, or it inherits it,
1706 -- DIC might be specified with a boolean value, meaning that the type
1707 -- is considered to be fully default initialized (SPARK RM 3.1 and
1708 -- SPARK RM 7.3.3). To avoid generating spurious warnings in this
1709 -- case, consider all types with DIC as fully initialized.
1711 elsif Has_Default_Init_Cond (Typ)
1712 or else Has_Inherited_Default_Init_Cond (Typ)
1717 return Is_Fully_Initialized_Type (Typ);
1719 end Is_OK_Fully_Initialized;
1721 ----------------------------
1722 -- Prefix_Has_Dereference --
1723 ----------------------------
1725 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1727 -- If prefix is of an access type, it certainly needs a dereference
1729 if Is_Access_Type (Etype (Pref)) then
1732 -- If prefix is explicit dereference, that's a dereference for sure
1734 elsif Nkind (Pref) = N_Explicit_Dereference then
1737 -- If prefix is itself a component reference or slice check prefix
1739 elsif Nkind (Pref) = N_Slice
1740 or else Nkind (Pref) = N_Indexed_Component
1741 or else Nkind (Pref) = N_Selected_Component
1743 return Prefix_Has_Dereference (Prefix (Pref));
1745 -- All other cases do not involve a dereference
1750 end Prefix_Has_Dereference;
1752 -- Start of processing for Check_Unset_Reference
1755 -- Nothing to do if warnings suppressed
1757 if Warning_Mode = Suppress then
1761 -- Nothing to do for numeric or string literal. Do this test early to
1762 -- save time in a common case (it does not matter that we do not include
1763 -- character literal here, since that will be caught later on in the
1764 -- when others branch of the case statement).
1766 if Nkind (N) in N_Numeric_Or_String_Literal then
1770 -- Ignore reference unless it comes from source. Almost always if we
1771 -- have a reference from generated code, it is bogus (e.g. calls to init
1772 -- procs to set default discriminant values).
1774 if not Comes_From_Source (N) then
1778 -- Otherwise see what kind of node we have. If the entity already has an
1779 -- unset reference, it is not necessarily the earliest in the text,
1780 -- because resolution of the prefix of selected components is completed
1781 -- before the resolution of the selected component itself. As a result,
1782 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1783 -- in right-to-left order. If there is already an unset reference, we
1784 -- check whether N is earlier before proceeding.
1788 -- For identifier or expanded name, examine the entity involved
1790 when N_Identifier | N_Expanded_Name =>
1792 E : constant Entity_Id := Entity (N);
1795 if Ekind_In (E, E_Variable, E_Out_Parameter)
1796 and then Never_Set_In_Source_Check_Spec (E)
1797 and then not Has_Initial_Value (E)
1798 and then (No (Unset_Reference (E))
1800 Earlier_In_Extended_Unit
1801 (Sloc (N), Sloc (Unset_Reference (E))))
1802 and then not Has_Pragma_Unmodified_Check_Spec (E)
1803 and then not Warnings_Off_Check_Spec (E)
1804 and then not Has_Junk_Name (E)
1806 -- We may have an unset reference. The first test is whether
1807 -- this is an access to a discriminant of a record or a
1808 -- component with default initialization. Both of these
1809 -- cases can be ignored, since the actual object that is
1810 -- referenced is definitely initialized. Note that this
1811 -- covers the case of reading discriminants of an OUT
1812 -- parameter, which is OK even in Ada 83.
1814 -- Note that we are only interested in a direct reference to
1815 -- a record component here. If the reference is through an
1816 -- access type, then the access object is being referenced,
1817 -- not the record, and still deserves an unset reference.
1819 if Nkind (Parent (N)) = N_Selected_Component
1820 and not Is_Access_Type (Typ)
1823 ES : constant Entity_Id :=
1824 Entity (Selector_Name (Parent (N)));
1826 if Ekind (ES) = E_Discriminant
1828 (Present (Declaration_Node (ES))
1830 Present (Expression (Declaration_Node (ES))))
1837 -- Exclude fully initialized types
1839 if Is_OK_Fully_Initialized then
1843 -- Here we have a potential unset reference. But before we
1844 -- get worried about it, we have to make sure that the
1845 -- entity declaration is in the same procedure as the
1846 -- reference, since if they are in separate procedures, then
1847 -- we have no idea about sequential execution.
1849 -- The tests in the loop below catch all such cases, but do
1850 -- allow the reference to appear in a loop, block, or
1851 -- package spec that is nested within the declaring scope.
1852 -- As always, it is possible to construct cases where the
1853 -- warning is wrong, that is why it is a warning.
1855 Potential_Unset_Reference : declare
1857 SE : constant Entity_Id := Scope (E);
1859 function Within_Postcondition return Boolean;
1860 -- Returns True if N is within a Postcondition, a
1861 -- Refined_Post, an Ensures component in a Test_Case,
1862 -- or a Contract_Cases.
1864 --------------------------
1865 -- Within_Postcondition --
1866 --------------------------
1868 function Within_Postcondition return Boolean is
1873 while Present (Nod) loop
1874 if Nkind (Nod) = N_Pragma
1875 and then Nam_In (Pragma_Name (Nod),
1878 Name_Contract_Cases)
1882 elsif Present (Parent (Nod)) then
1885 if Nkind (P) = N_Pragma
1886 and then Pragma_Name (P) = Name_Test_Case
1887 and then Nod = Test_Case_Arg (P, Name_Ensures)
1893 Nod := Parent (Nod);
1897 end Within_Postcondition;
1899 -- Start of processing for Potential_Unset_Reference
1902 SR := Current_Scope;
1904 if SR = Standard_Standard
1905 or else Is_Subprogram (SR)
1906 or else Is_Concurrent_Body (SR)
1907 or else Is_Concurrent_Type (SR)
1915 -- Case of reference has an access type. This is a
1916 -- special case since access types are always set to null
1917 -- so cannot be truly uninitialized, but we still want to
1918 -- warn about cases of obvious null dereference.
1920 if Is_Access_Type (Typ) then
1921 Access_Type_Case : declare
1925 (N : Node_Id) return Traverse_Result;
1926 -- Process function for instantiation of Traverse
1927 -- below. Checks if N contains reference to E other
1928 -- than a dereference.
1930 function Ref_In (Nod : Node_Id) return Boolean;
1931 -- Determines whether Nod contains a reference to
1932 -- the entity E that is not a dereference.
1939 (N : Node_Id) return Traverse_Result
1942 if Is_Entity_Name (N)
1943 and then Entity (N) = E
1944 and then not Is_Dereferenced (N)
1956 function Ref_In (Nod : Node_Id) return Boolean is
1957 function Traverse is new Traverse_Func (Process);
1959 return Traverse (Nod) = Abandon;
1962 -- Start of processing for Access_Type_Case
1965 -- Don't bother if we are inside an instance, since
1966 -- the compilation of the generic template is where
1967 -- the warning should be issued.
1973 -- Don't bother if this is not the main unit. If we
1974 -- try to give this warning for with'ed units, we
1975 -- get some false positives, since we do not record
1976 -- references in other units.
1978 if not In_Extended_Main_Source_Unit (E)
1980 not In_Extended_Main_Source_Unit (N)
1985 -- We are only interested in dereferences
1987 if not Is_Dereferenced (N) then
1991 -- One more check, don't bother with references
1992 -- that are inside conditional statements or WHILE
1993 -- loops if the condition references the entity in
1994 -- question. This avoids most false positives.
2001 if Nkind_In (P, N_If_Statement, N_Elsif_Part)
2002 and then Ref_In (Condition (P))
2006 elsif Nkind (P) = N_Loop_Statement
2007 and then Present (Iteration_Scheme (P))
2009 Ref_In (Condition (Iteration_Scheme (P)))
2014 end Access_Type_Case;
2017 -- One more check, don't bother if we are within a
2018 -- postcondition, since the expression occurs in a
2019 -- place unrelated to the actual test.
2021 if not Within_Postcondition then
2023 -- Here we definitely have a case for giving a warning
2024 -- for a reference to an unset value. But we don't
2025 -- give the warning now. Instead set Unset_Reference
2026 -- in the identifier involved. The reason for this is
2027 -- that if we find the variable is never ever assigned
2028 -- a value then that warning is more important and
2029 -- there is no point in giving the reference warning.
2031 -- If this is an identifier, set the field directly
2033 if Nkind (N) = N_Identifier then
2034 Set_Unset_Reference (E, N);
2036 -- Otherwise it is an expanded name, so set the field
2037 -- of the actual identifier for the reference.
2040 Set_Unset_Reference (E, Selector_Name (N));
2043 end Potential_Unset_Reference;
2047 -- Indexed component or slice
2049 when N_Indexed_Component | N_Slice =>
2051 -- If prefix does not involve dereferencing an access type, then
2052 -- we know we are OK if the component type is fully initialized,
2053 -- since the component will have been set as part of the default
2056 if not Prefix_Has_Dereference (Prefix (N))
2057 and then Is_OK_Fully_Initialized
2061 -- Look at prefix in access type case, or if the component is not
2062 -- fully initialized.
2065 Check_Unset_Reference (Prefix (N));
2070 when N_Selected_Component =>
2072 Pref : constant Node_Id := Prefix (N);
2073 Ent : constant Entity_Id := Entity (Selector_Name (N));
2076 -- If prefix involves dereferencing an access type, always
2077 -- check the prefix, since the issue then is whether this
2078 -- access value is null.
2080 if Prefix_Has_Dereference (Pref) then
2083 -- Always go to prefix if no selector entity is set. Can this
2084 -- happen in the normal case? Not clear, but it definitely can
2085 -- happen in error cases.
2090 -- For a record component, check some cases where we have
2091 -- reasonable cause to consider that the component is known to
2092 -- be or probably is initialized. In this case, we don't care
2093 -- if the prefix itself was explicitly initialized.
2095 -- Discriminants are always considered initialized
2097 elsif Ekind (Ent) = E_Discriminant then
2100 -- An explicitly initialized component is certainly initialized
2102 elsif Nkind (Parent (Ent)) = N_Component_Declaration
2103 and then Present (Expression (Parent (Ent)))
2107 -- A fully initialized component is initialized
2109 elsif Is_OK_Fully_Initialized then
2113 -- If none of those cases apply, check the record type prefix
2115 Check_Unset_Reference (Pref);
2118 -- For type conversions, qualifications, or expressions with actions,
2119 -- examine the expression.
2121 when N_Type_Conversion |
2122 N_Qualified_Expression |
2123 N_Expression_With_Actions =>
2124 Check_Unset_Reference (Expression (N));
2126 -- For explicit dereference, always check prefix, which will generate
2127 -- an unset reference (since this is a case of dereferencing null).
2129 when N_Explicit_Dereference =>
2130 Check_Unset_Reference (Prefix (N));
2132 -- All other cases are not cases of an unset reference
2138 end Check_Unset_Reference;
2140 ------------------------
2141 -- Check_Unused_Withs --
2142 ------------------------
2144 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2150 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2151 -- This is needed for checking the special renaming case
2153 procedure Check_One_Unit (Unit : Unit_Number_Type);
2154 -- Subsidiary procedure, performs checks for specified unit
2156 --------------------
2157 -- Check_One_Unit --
2158 --------------------
2160 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2161 Is_Visible_Renaming : Boolean := False;
2164 procedure Check_Inner_Package (Pack : Entity_Id);
2165 -- Pack is a package local to a unit in a with_clause. Both the unit
2166 -- and Pack are referenced. If none of the entities in Pack are
2167 -- referenced, then the only occurrence of Pack is in a USE clause
2168 -- or a pragma, and a warning is worthwhile as well.
2170 function Check_System_Aux return Boolean;
2171 -- Before giving a warning on a with_clause for System, check whether
2172 -- a system extension is present.
2174 function Find_Package_Renaming
2176 L : Entity_Id) return Entity_Id;
2177 -- The only reference to a context unit may be in a renaming
2178 -- declaration. If this renaming declares a visible entity, do not
2179 -- warn that the context clause could be moved to the body, because
2180 -- the renaming may be intended to re-export the unit.
2182 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2183 -- This function determines if a package has any visible entities.
2184 -- True is returned if there is at least one declared visible entity,
2185 -- otherwise False is returned (e.g. case of only pragmas present).
2187 -------------------------
2188 -- Check_Inner_Package --
2189 -------------------------
2191 procedure Check_Inner_Package (Pack : Entity_Id) is
2193 Un : constant Node_Id := Sinfo.Unit (Cnode);
2195 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2196 -- If N is a use_clause for Pack, emit warning
2198 procedure Check_Use_Clauses is new
2199 Traverse_Proc (Check_Use_Clause);
2201 ----------------------
2202 -- Check_Use_Clause --
2203 ----------------------
2205 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2209 if Nkind (N) = N_Use_Package_Clause then
2210 Nam := First (Names (N));
2211 while Present (Nam) loop
2212 if Entity (Nam) = Pack then
2214 -- Suppress message if any serious errors detected
2215 -- that turn off expansion, and thus result in false
2216 -- positives for this warning.
2218 if Serious_Errors_Detected = 0 then
2219 Error_Msg_Qual_Level := 1;
2220 Error_Msg_NE -- CODEFIX
2221 ("?u?no entities of package& are referenced!",
2223 Error_Msg_Qual_Level := 0;
2232 end Check_Use_Clause;
2234 -- Start of processing for Check_Inner_Package
2237 E := First_Entity (Pack);
2238 while Present (E) loop
2239 if Referenced_Check_Spec (E) then
2246 -- No entities of the package are referenced. Check whether the
2247 -- reference to the package itself is a use clause, and if so
2248 -- place a warning on it.
2250 Check_Use_Clauses (Un);
2251 end Check_Inner_Package;
2253 ----------------------
2254 -- Check_System_Aux --
2255 ----------------------
2257 function Check_System_Aux return Boolean is
2261 if Chars (Lunit) = Name_System
2262 and then Scope (Lunit) = Standard_Standard
2263 and then Present_System_Aux
2265 Ent := First_Entity (System_Aux_Id);
2266 while Present (Ent) loop
2267 if Referenced_Check_Spec (Ent) then
2276 end Check_System_Aux;
2278 ---------------------------
2279 -- Find_Package_Renaming --
2280 ---------------------------
2282 function Find_Package_Renaming
2284 L : Entity_Id) return Entity_Id
2290 Is_Visible_Renaming := False;
2292 E1 := First_Entity (P);
2293 while Present (E1) loop
2294 if Ekind (E1) = E_Package and then Renamed_Object (E1) = L then
2295 Is_Visible_Renaming := not Is_Hidden (E1);
2298 elsif Ekind (E1) = E_Package
2299 and then No (Renamed_Object (E1))
2300 and then not Is_Generic_Instance (E1)
2302 R := Find_Package_Renaming (E1, L);
2305 Is_Visible_Renaming := not Is_Hidden (R);
2314 end Find_Package_Renaming;
2316 --------------------------
2317 -- Has_Visible_Entities --
2318 --------------------------
2320 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2324 -- If unit in context is not a package, it is a subprogram that
2325 -- is not called or a generic unit that is not instantiated
2326 -- in the current unit, and warning is appropriate.
2328 if Ekind (P) /= E_Package then
2332 -- If unit comes from a limited_with clause, look for declaration
2333 -- of shadow entities.
2335 if Present (Limited_View (P)) then
2336 E := First_Entity (Limited_View (P));
2338 E := First_Entity (P);
2341 while Present (E) and then E /= First_Private_Entity (P) loop
2342 if Comes_From_Source (E) or else Present (Limited_View (P)) then
2350 end Has_Visible_Entities;
2352 -- Start of processing for Check_One_Unit
2355 Cnode := Cunit (Unit);
2357 -- Only do check in units that are part of the extended main unit.
2358 -- This is actually a necessary restriction, because in the case of
2359 -- subprogram acting as its own specification, there can be with's in
2360 -- subunits that we will not see.
2362 if not In_Extended_Main_Source_Unit (Cnode) then
2365 -- In configurable run time mode, we remove the bodies of non-inlined
2366 -- subprograms, which may lead to spurious warnings, which are
2367 -- clearly undesirable.
2369 elsif Configurable_Run_Time_Mode
2370 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2375 -- Loop through context items in this unit
2377 Item := First (Context_Items (Cnode));
2378 while Present (Item) loop
2379 if Nkind (Item) = N_With_Clause
2380 and then not Implicit_With (Item)
2381 and then In_Extended_Main_Source_Unit (Item)
2383 -- Guard for no entity present. Not clear under what conditions
2384 -- this happens, but it does occur, and since this is only a
2385 -- warning, we just suppress the warning in this case.
2387 and then Nkind (Name (Item)) in N_Has_Entity
2388 and then Present (Entity (Name (Item)))
2390 Lunit := Entity (Name (Item));
2392 -- Check if this unit is referenced (skip the check if this
2393 -- is explicitly marked by a pragma Unreferenced).
2395 if not Referenced (Lunit) and then not Has_Unreferenced (Lunit)
2397 -- Suppress warnings in internal units if not in -gnatg mode
2398 -- (these would be junk warnings for an application program,
2399 -- since they refer to problems in internal units).
2402 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2404 -- Here we definitely have a non-referenced unit. If it
2405 -- is the special call for a spec unit, then just set the
2406 -- flag to be read later.
2408 if Unit = Spec_Unit then
2409 Set_Unreferenced_In_Spec (Item);
2411 -- Otherwise simple unreferenced message, but skip this
2412 -- if no visible entities, because that is most likely a
2413 -- case where warning would be false positive (e.g. a
2414 -- package with only a linker options pragma and nothing
2415 -- else or a pragma elaborate with a body library task).
2417 elsif Has_Visible_Entities (Entity (Name (Item))) then
2418 Error_Msg_N -- CODEFIX
2419 ("?u?unit& is not referenced!", Name (Item));
2423 -- If main unit is a renaming of this unit, then we consider
2424 -- the with to be OK (obviously it is needed in this case).
2425 -- This may be transitive: the unit in the with_clause may
2426 -- itself be a renaming, in which case both it and the main
2427 -- unit rename the same ultimate package.
2429 elsif Present (Renamed_Entity (Munite))
2431 (Renamed_Entity (Munite) = Lunit
2432 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2436 -- If this unit is referenced, and it is a package, we do
2437 -- another test, to see if any of the entities in the package
2438 -- are referenced. If none of the entities are referenced, we
2439 -- still post a warning. This occurs if the only use of the
2440 -- package is in a use clause, or in a package renaming
2441 -- declaration. This check is skipped for packages that are
2442 -- renamed in a spec, since the entities in such a package are
2443 -- visible to clients via the renaming.
2445 elsif Ekind (Lunit) = E_Package
2446 and then not Renamed_In_Spec (Lunit)
2448 -- If Is_Instantiated is set, it means that the package is
2449 -- implicitly instantiated (this is the case of parent
2450 -- instance or an actual for a generic package formal), and
2451 -- this counts as a reference.
2453 if Is_Instantiated (Lunit) then
2456 -- If no entities in package, and there is a pragma
2457 -- Elaborate_Body present, then assume that this with is
2458 -- done for purposes of this elaboration.
2460 elsif No (First_Entity (Lunit))
2461 and then Has_Pragma_Elaborate_Body (Lunit)
2465 -- Otherwise see if any entities have been referenced
2468 if Limited_Present (Item) then
2469 Ent := First_Entity (Limited_View (Lunit));
2471 Ent := First_Entity (Lunit);
2475 -- No more entities, and we did not find one that was
2476 -- referenced. Means we have a definite case of a with
2477 -- none of whose entities was referenced.
2481 -- If in spec, just set the flag
2483 if Unit = Spec_Unit then
2484 Set_No_Entities_Ref_In_Spec (Item);
2486 elsif Check_System_Aux then
2489 -- Else the warning may be needed
2493 Eitem : constant Entity_Id :=
2494 Entity (Name (Item));
2497 -- Warn if we unreferenced flag set and we
2498 -- have not had serious errors. The reason we
2499 -- inhibit the message if there are errors is
2500 -- to prevent false positives from disabling
2503 if not Has_Unreferenced (Eitem)
2504 and then Serious_Errors_Detected = 0
2506 -- Get possible package renaming
2509 Find_Package_Renaming (Munite, Lunit);
2511 -- No warning if either the package or its
2512 -- renaming is used as a generic actual.
2514 if Used_As_Generic_Actual (Eitem)
2518 Used_As_Generic_Actual (Pack))
2523 -- Here we give the warning
2525 Error_Msg_N -- CODEFIX
2526 ("?u?no entities of & are referenced!",
2529 -- Flag renaming of package as well. If
2530 -- the original package has warnings off,
2531 -- we suppress the warning on the renaming
2535 and then not Has_Warnings_Off (Lunit)
2536 and then not Has_Unreferenced (Pack)
2538 Error_Msg_NE -- CODEFIX
2539 ("?u?no entities of& are referenced!",
2540 Unit_Declaration_Node (Pack), Pack);
2548 -- Case of entity being referenced. The reference may
2549 -- come from a limited_with_clause, in which case the
2550 -- limited view of the entity carries the flag.
2552 elsif Referenced_Check_Spec (Ent)
2553 or else Referenced_As_LHS_Check_Spec (Ent)
2554 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2556 (From_Limited_With (Ent)
2557 and then Is_Incomplete_Type (Ent)
2558 and then Present (Non_Limited_View (Ent))
2559 and then Referenced (Non_Limited_View (Ent)))
2561 -- This means that the with is indeed fine, in that
2562 -- it is definitely needed somewhere, and we can
2563 -- quit worrying about this one...
2565 -- Except for one little detail: if either of the
2566 -- flags was set during spec processing, this is
2567 -- where we complain that the with could be moved
2568 -- from the spec. If the spec contains a visible
2569 -- renaming of the package, inhibit warning to move
2570 -- with_clause to body.
2572 if Ekind (Munite) = E_Package_Body then
2574 Find_Package_Renaming
2575 (Spec_Entity (Munite), Lunit);
2580 -- If a renaming is present in the spec do not warn
2581 -- because the body or child unit may depend on it.
2584 and then Renamed_Entity (Pack) = Lunit
2588 elsif Unreferenced_In_Spec (Item) then
2589 Error_Msg_N -- CODEFIX
2590 ("?u?unit& is not referenced in spec!",
2593 elsif No_Entities_Ref_In_Spec (Item) then
2594 Error_Msg_N -- CODEFIX
2595 ("?u?no entities of & are referenced in spec!",
2599 if Ekind (Ent) = E_Package then
2600 Check_Inner_Package (Ent);
2606 if not Is_Visible_Renaming then
2607 Error_Msg_N -- CODEFIX
2608 ("\?u?with clause might be moved to body!",
2614 -- Move to next entity to continue search
2622 -- For a generic package, the only interesting kind of
2623 -- reference is an instantiation, since entities cannot be
2624 -- referenced directly.
2626 elsif Is_Generic_Unit (Lunit) then
2628 -- Unit was never instantiated, set flag for case of spec
2629 -- call, or give warning for normal call.
2631 if not Is_Instantiated (Lunit) then
2632 if Unit = Spec_Unit then
2633 Set_Unreferenced_In_Spec (Item);
2635 Error_Msg_N -- CODEFIX
2636 ("?u?unit& is never instantiated!", Name (Item));
2639 -- If unit was indeed instantiated, make sure that flag is
2640 -- not set showing it was uninstantiated in the spec, and if
2641 -- so, give warning.
2643 elsif Unreferenced_In_Spec (Item) then
2645 ("?u?unit& is not instantiated in spec!", Name (Item));
2646 Error_Msg_N -- CODEFIX
2647 ("\?u?with clause can be moved to body!", Name (Item));
2656 -- Start of processing for Check_Unused_Withs
2659 -- Immediate return if no semantics or warning flag not set
2661 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then
2665 Process_Deferred_References;
2667 -- Flag any unused with clauses. For a subunit, check only the units
2668 -- in its context, not those of the parent, which may be needed by other
2669 -- subunits. We will get the full warnings when we compile the parent,
2670 -- but the following is helpful when compiling a subunit by itself.
2672 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2673 if Current_Sem_Unit = Main_Unit then
2674 Check_One_Unit (Main_Unit);
2680 -- Process specified units
2682 if Spec_Unit = No_Unit then
2684 -- For main call, check all units
2686 for Unit in Main_Unit .. Last_Unit loop
2687 Check_One_Unit (Unit);
2691 -- For call for spec, check only the spec
2693 Check_One_Unit (Spec_Unit);
2695 end Check_Unused_Withs;
2697 ---------------------------------
2698 -- Generic_Package_Spec_Entity --
2699 ---------------------------------
2701 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2705 if Is_Package_Body_Entity (E) then
2711 if S = Standard_Standard then
2714 elsif Ekind (S) = E_Generic_Package then
2717 elsif Ekind (S) = E_Package then
2725 end Generic_Package_Spec_Entity;
2727 ----------------------
2728 -- Goto_Spec_Entity --
2729 ----------------------
2731 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2733 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2734 return Spec_Entity (E);
2738 end Goto_Spec_Entity;
2744 function Has_Junk_Name (E : Entity_Id) return Boolean is
2745 function Match (S : String) return Boolean;
2746 -- Return true if substring S is found in Name_Buffer (1 .. Name_Len)
2752 function Match (S : String) return Boolean is
2753 Slen1 : constant Integer := S'Length - 1;
2756 for J in 1 .. Name_Len - S'Length + 1 loop
2757 if Name_Buffer (J .. J + Slen1) = S then
2765 -- Start of processing for Has_Junk_Name
2768 Get_Unqualified_Decoded_Name_String (Chars (E));
2771 Match ("discard") or else
2772 Match ("dummy") or else
2773 Match ("ignore") or else
2774 Match ("junk") or else
2778 --------------------------------------
2779 -- Has_Pragma_Unmodified_Check_Spec --
2780 --------------------------------------
2782 function Has_Pragma_Unmodified_Check_Spec
2783 (E : Entity_Id) return Boolean
2786 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2788 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2789 -- to mess with Unmodified flags on both body and spec entities.
2791 return Has_Unmodified (E)
2793 Has_Unmodified (Spec_Entity (E));
2796 return Has_Unmodified (E);
2798 end Has_Pragma_Unmodified_Check_Spec;
2800 ----------------------------------------
2801 -- Has_Pragma_Unreferenced_Check_Spec --
2802 ----------------------------------------
2804 function Has_Pragma_Unreferenced_Check_Spec
2805 (E : Entity_Id) return Boolean
2808 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2810 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2811 -- to mess with flags on both entities.
2813 return Has_Unreferenced (E)
2815 Has_Unreferenced (Spec_Entity (E));
2818 return Has_Unreferenced (E);
2820 end Has_Pragma_Unreferenced_Check_Spec;
2826 procedure Initialize is
2828 Warnings_Off_Pragmas.Init;
2829 Unreferenced_Entities.Init;
2830 In_Out_Warnings.Init;
2833 ------------------------------------
2834 -- Never_Set_In_Source_Check_Spec --
2835 ------------------------------------
2837 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2839 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2840 return Never_Set_In_Source (E)
2842 Never_Set_In_Source (Spec_Entity (E));
2844 return Never_Set_In_Source (E);
2846 end Never_Set_In_Source_Check_Spec;
2848 -------------------------------------
2849 -- Operand_Has_Warnings_Suppressed --
2850 -------------------------------------
2852 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2854 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2855 -- Function used to check one node to see if it is or was originally
2856 -- a reference to an entity for which Warnings are off. If so, Abandon
2857 -- is returned, otherwise OK_Orig is returned to continue the traversal
2858 -- of the original expression.
2860 function Traverse is new Traverse_Func (Check_For_Warnings);
2861 -- Function used to traverse tree looking for warnings
2863 ------------------------
2864 -- Check_For_Warnings --
2865 ------------------------
2867 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2868 R : constant Node_Id := Original_Node (N);
2871 if Nkind (R) in N_Has_Entity
2872 and then Present (Entity (R))
2873 and then Has_Warnings_Off (Entity (R))
2879 end Check_For_Warnings;
2881 -- Start of processing for Operand_Has_Warnings_Suppressed
2884 return Traverse (N) = Abandon;
2886 -- If any exception occurs, then something has gone wrong, and this is
2887 -- only a minor aesthetic issue anyway, so just say we did not find what
2888 -- we are looking for, rather than blow up.
2893 end Operand_Has_Warnings_Suppressed;
2895 -----------------------------------------
2896 -- Output_Non_Modified_In_Out_Warnings --
2897 -----------------------------------------
2899 procedure Output_Non_Modified_In_Out_Warnings is
2901 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2902 -- Given a formal parameter entity E, determines if there is a reason to
2903 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2904 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2905 -- if we have seen the address of the subprogram being taken, or if the
2906 -- subprogram is used as a generic actual (in the latter cases the
2907 -- context may force use of IN OUT, even if the parameter is not
2908 -- modifies for this particular case.
2910 -----------------------
2911 -- No_Warn_On_In_Out --
2912 -----------------------
2914 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2915 S : constant Entity_Id := Scope (E);
2916 SE : constant Entity_Id := Spec_Entity (E);
2919 -- Do not warn if address is taken, since funny business may be going
2920 -- on in treating the parameter indirectly as IN OUT.
2922 if Address_Taken (S)
2923 or else (Present (SE) and then Address_Taken (Scope (SE)))
2927 -- Do not warn if used as a generic actual, since the generic may be
2928 -- what is forcing the use of an "unnecessary" IN OUT.
2930 elsif Used_As_Generic_Actual (S)
2931 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2935 -- Else test warnings off
2937 elsif Warnings_Off_Check_Spec (S) then
2940 -- All tests for suppressing warning failed
2945 end No_Warn_On_In_Out;
2947 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2950 -- Loop through entities for which a warning may be needed
2952 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2954 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2957 -- Suppress warning in specific cases (see details in comments for
2958 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2960 if Has_Pragma_Unmodified_Check_Spec (E1)
2961 or else No_Warn_On_In_Out (E1)
2965 -- Here we generate the warning
2968 -- If -gnatwc is set then output message that we could be IN
2970 if not Is_Trivial_Subprogram (Scope (E1)) then
2971 if Warn_On_Constant then
2973 ("?u?formal parameter & is not modified!", E1);
2975 ("\?u?mode could be IN instead of `IN OUT`!", E1);
2977 -- We do not generate warnings for IN OUT parameters
2978 -- unless we have at least -gnatwu. This is deliberately
2979 -- inconsistent with the treatment of variables, but
2980 -- otherwise we get too many unexpected warnings in
2983 elsif Check_Unreferenced then
2985 ("?u?formal parameter& is read but "
2986 & "never assigned!", E1);
2990 -- Kill any other warnings on this entity, since this is the
2991 -- one that should dominate any other unreferenced warning.
2993 Set_Warnings_Off (E1);
2997 end Output_Non_Modified_In_Out_Warnings;
2999 ----------------------------------------
3000 -- Output_Obsolescent_Entity_Warnings --
3001 ----------------------------------------
3003 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
3004 P : constant Node_Id := Parent (N);
3010 -- Do not output message if we are the scope of standard. This means
3011 -- we have a reference from a context clause from when it is originally
3012 -- processed, and that's too early to tell whether it is an obsolescent
3013 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
3014 -- sure that we have a later call when the scope is available. This test
3015 -- also eliminates all messages for use clauses, which is fine (we do
3016 -- not want messages for use clauses, since they are always redundant
3017 -- with respect to the associated with clause).
3019 if S = Standard_Standard then
3023 -- Do not output message if we are in scope of an obsolescent package
3027 if Is_Obsolescent (S) then
3032 exit when S = Standard_Standard;
3035 -- Here we will output the message
3037 Error_Msg_Sloc := Sloc (E);
3039 -- Case of with clause
3041 if Nkind (P) = N_With_Clause then
3042 if Ekind (E) = E_Package then
3044 ("?j?with of obsolescent package& declared#", N, E);
3045 elsif Ekind (E) = E_Procedure then
3047 ("?j?with of obsolescent procedure& declared#", N, E);
3050 ("??with of obsolescent function& declared#", N, E);
3053 -- If we do not have a with clause, then ignore any reference to an
3054 -- obsolescent package name. We only want to give the one warning of
3055 -- withing the package, not one each time it is used to qualify.
3057 elsif Ekind (E) = E_Package then
3060 -- Procedure call statement
3062 elsif Nkind (P) = N_Procedure_Call_Statement then
3064 ("??call to obsolescent procedure& declared#", N, E);
3068 elsif Nkind (P) = N_Function_Call then
3070 ("??call to obsolescent function& declared#", N, E);
3072 -- Reference to obsolescent type
3074 elsif Is_Type (E) then
3076 ("??reference to obsolescent type& declared#", N, E);
3078 -- Reference to obsolescent component
3080 elsif Ekind_In (E, E_Component, E_Discriminant) then
3082 ("??reference to obsolescent component& declared#", N, E);
3084 -- Reference to obsolescent variable
3086 elsif Ekind (E) = E_Variable then
3088 ("??reference to obsolescent variable& declared#", N, E);
3090 -- Reference to obsolescent constant
3092 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then
3094 ("??reference to obsolescent constant& declared#", N, E);
3096 -- Reference to obsolescent enumeration literal
3098 elsif Ekind (E) = E_Enumeration_Literal then
3100 ("??reference to obsolescent enumeration literal& declared#", N, E);
3102 -- Generic message for any other case we missed
3106 ("??reference to obsolescent entity& declared#", N, E);
3109 -- Output additional warning if present
3111 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
3112 if Obsolescent_Warnings.Table (J).Ent = E then
3113 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
3114 Error_Msg_Strlen := Name_Len;
3115 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
3116 Error_Msg_N ("\\??~", N);
3120 end Output_Obsolescent_Entity_Warnings;
3122 ----------------------------------
3123 -- Output_Unreferenced_Messages --
3124 ----------------------------------
3126 procedure Output_Unreferenced_Messages is
3128 for J in Unreferenced_Entities.First .. Unreferenced_Entities.Last loop
3129 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
3131 end Output_Unreferenced_Messages;
3133 -----------------------------------------
3134 -- Output_Unused_Warnings_Off_Warnings --
3135 -----------------------------------------
3137 procedure Output_Unused_Warnings_Off_Warnings is
3139 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
3141 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
3142 N : Node_Id renames Wentry.N;
3143 E : Node_Id renames Wentry.E;
3146 -- Turn off Warnings_Off, or we won't get the warning
3148 Set_Warnings_Off (E, False);
3150 -- Nothing to do if pragma was used to suppress a general warning
3152 if Warnings_Off_Used (E) then
3155 -- If pragma was used both in unmodified and unreferenced contexts
3156 -- then that's as good as the general case, no warning.
3158 elsif Warnings_Off_Used_Unmodified (E)
3160 Warnings_Off_Used_Unreferenced (E)
3164 -- Used only in context where Unmodified would have worked
3166 elsif Warnings_Off_Used_Unmodified (E) then
3168 ("?W?could use Unmodified instead of "
3169 & "Warnings Off for &", Pragma_Identifier (N), E);
3171 -- Used only in context where Unreferenced would have worked
3173 elsif Warnings_Off_Used_Unreferenced (E) then
3175 ("?W?could use Unreferenced instead of "
3176 & "Warnings Off for &", Pragma_Identifier (N), E);
3182 ("?W?pragma Warnings Off for & unused, "
3183 & "could be omitted", N, E);
3187 end Output_Unused_Warnings_Off_Warnings;
3189 ---------------------------
3190 -- Referenced_Check_Spec --
3191 ---------------------------
3193 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3195 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3196 return Referenced (E) or else Referenced (Spec_Entity (E));
3198 return Referenced (E);
3200 end Referenced_Check_Spec;
3202 ----------------------------------
3203 -- Referenced_As_LHS_Check_Spec --
3204 ----------------------------------
3206 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3208 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3209 return Referenced_As_LHS (E)
3210 or else Referenced_As_LHS (Spec_Entity (E));
3212 return Referenced_As_LHS (E);
3214 end Referenced_As_LHS_Check_Spec;
3216 --------------------------------------------
3217 -- Referenced_As_Out_Parameter_Check_Spec --
3218 --------------------------------------------
3220 function Referenced_As_Out_Parameter_Check_Spec
3221 (E : Entity_Id) return Boolean
3224 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3225 return Referenced_As_Out_Parameter (E)
3226 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3228 return Referenced_As_Out_Parameter (E);
3230 end Referenced_As_Out_Parameter_Check_Spec;
3232 -----------------------------
3233 -- Warn_On_Known_Condition --
3234 -----------------------------
3236 procedure Warn_On_Known_Condition (C : Node_Id) is
3238 Orig : constant Node_Id := Original_Node (C);
3239 Test_Result : Boolean;
3241 function Is_Known_Branch return Boolean;
3242 -- If the type of the condition is Boolean, the constant value of the
3243 -- condition is a boolean literal. If the type is a derived boolean
3244 -- type, the constant is wrapped in a type conversion of the derived
3245 -- literal. If the value of the condition is not a literal, no warnings
3246 -- can be produced. This function returns True if the result can be
3247 -- determined, and Test_Result is set True/False accordingly. Otherwise
3248 -- False is returned, and Test_Result is unchanged.
3250 procedure Track (N : Node_Id; Loc : Node_Id);
3251 -- Adds continuation warning(s) pointing to reason (assignment or test)
3252 -- for the operand of the conditional having a known value (or at least
3253 -- enough is known about the value to issue the warning). N is the node
3254 -- which is judged to have a known value. Loc is the warning location.
3256 ---------------------
3257 -- Is_Known_Branch --
3258 ---------------------
3260 function Is_Known_Branch return Boolean is
3262 if Etype (C) = Standard_Boolean
3263 and then Is_Entity_Name (C)
3265 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3267 Test_Result := Entity (C) = Standard_True;
3270 elsif Is_Boolean_Type (Etype (C))
3271 and then Nkind (C) = N_Unchecked_Type_Conversion
3272 and then Is_Entity_Name (Expression (C))
3273 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3276 Chars (Entity (Expression (C))) = Chars (Standard_True);
3282 end Is_Known_Branch;
3288 procedure Track (N : Node_Id; Loc : Node_Id) is
3289 Nod : constant Node_Id := Original_Node (N);
3292 if Nkind (Nod) in N_Op_Compare then
3293 Track (Left_Opnd (Nod), Loc);
3294 Track (Right_Opnd (Nod), Loc);
3296 elsif Is_Entity_Name (Nod) and then Is_Object (Entity (Nod)) then
3298 CV : constant Node_Id := Current_Value (Entity (Nod));
3301 if Present (CV) then
3302 Error_Msg_Sloc := Sloc (CV);
3304 if Nkind (CV) not in N_Subexpr then
3305 Error_Msg_N ("\\??(see test #)", Loc);
3307 elsif Nkind (Parent (CV)) =
3308 N_Case_Statement_Alternative
3310 Error_Msg_N ("\\??(see case alternative #)", Loc);
3313 Error_Msg_N ("\\??(see assignment #)", Loc);
3320 -- Start of processing for Warn_On_Known_Condition
3323 -- Adjust SCO condition if from source
3326 and then Comes_From_Source (Orig)
3327 and then Is_Known_Branch
3333 Atrue := Test_Result;
3335 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3339 Set_SCO_Condition (Orig, Atrue);
3343 -- Argument replacement in an inlined body can make conditions static.
3344 -- Do not emit warnings in this case.
3346 if In_Inlined_Body then
3350 if Constant_Condition_Warnings
3351 and then Is_Known_Branch
3352 and then Comes_From_Source (Orig)
3353 and then not In_Instance
3355 -- Don't warn if comparison of result of attribute against a constant
3356 -- value, since this is likely legitimate conditional compilation.
3358 if Nkind (Orig) in N_Op_Compare
3359 and then Compile_Time_Known_Value (Right_Opnd (Orig))
3360 and then Nkind (Original_Node (Left_Opnd (Orig))) =
3361 N_Attribute_Reference
3366 -- See if this is in a statement or a declaration
3370 -- If tree is not attached, do not issue warning (this is very
3371 -- peculiar, and probably arises from some other error condition)
3376 -- If we are in a declaration, then no warning, since in practice
3377 -- conditionals in declarations are used for intended tests which
3378 -- may be known at compile time, e.g. things like
3380 -- x : constant Integer := 2 + (Word'Size = 32);
3382 -- And a warning is annoying in such cases
3384 elsif Nkind (P) in N_Declaration
3386 Nkind (P) in N_Later_Decl_Item
3390 -- Don't warn in assert or check pragma, since presumably tests in
3391 -- such a context are very definitely intended, and might well be
3392 -- known at compile time. Note that we have to test the original
3393 -- node, since assert pragmas get rewritten at analysis time.
3395 elsif Nkind (Original_Node (P)) = N_Pragma
3396 and then Nam_In (Pragma_Name (Original_Node (P)), Name_Assert,
3402 exit when Is_Statement (P);
3406 -- Here we issue the warning unless some sub-operand has warnings
3407 -- set off, in which case we suppress the warning for the node. If
3408 -- the original expression is an inequality, it has been expanded
3409 -- into a negation, and the value of the original expression is the
3410 -- negation of the equality. If the expression is an entity that
3411 -- appears within a negation, it is clearer to flag the negation
3412 -- itself, and report on its constant value.
3414 if not Operand_Has_Warnings_Suppressed (C) then
3416 True_Branch : Boolean := Test_Result;
3417 Cond : Node_Id := C;
3420 if Present (Parent (C))
3421 and then Nkind (Parent (C)) = N_Op_Not
3423 True_Branch := not True_Branch;
3427 -- Condition always True
3430 if Is_Entity_Name (Original_Node (C))
3431 and then Nkind (Cond) /= N_Op_Not
3434 ("object & is always True at this point?c?",
3435 Cond, Original_Node (C));
3436 Track (Original_Node (C), Cond);
3439 Error_Msg_N ("condition is always True?c?", Cond);
3443 -- Condition always False
3446 if Is_Entity_Name (Original_Node (C))
3447 and then Nkind (Cond) /= N_Op_Not
3450 ("object & is always False at this point?c?",
3451 Cond, Original_Node (C));
3452 Track (Original_Node (C), Cond);
3455 Error_Msg_N ("condition is always False?c?", Cond);
3462 end Warn_On_Known_Condition;
3464 ---------------------------------------
3465 -- Warn_On_Modified_As_Out_Parameter --
3466 ---------------------------------------
3468 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3471 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3472 or else Warn_On_All_Unread_Out_Parameters;
3473 end Warn_On_Modified_As_Out_Parameter;
3475 ---------------------------------
3476 -- Warn_On_Overlapping_Actuals --
3477 ---------------------------------
3479 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3480 Act1, Act2 : Node_Id;
3481 Form1, Form2 : Entity_Id;
3483 function Is_Covered_Formal (Formal : Node_Id) return Boolean;
3484 -- Return True if Formal is covered by the rule
3486 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean;
3487 -- Two names are known to refer to the same object if the two names
3488 -- are known to denote the same object; or one of the names is a
3489 -- selected_component, indexed_component, or slice and its prefix is
3490 -- known to refer to the same object as the other name; or one of the
3491 -- two names statically denotes a renaming declaration whose renamed
3492 -- object_name is known to refer to the same object as the other name
3493 -- (RM 6.4.1(6.11/3))
3495 -----------------------
3496 -- Refer_Same_Object --
3497 -----------------------
3499 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is
3501 return Denotes_Same_Object (Act1, Act2)
3502 or else Denotes_Same_Prefix (Act1, Act2);
3503 end Refer_Same_Object;
3505 -----------------------
3506 -- Is_Covered_Formal --
3507 -----------------------
3509 function Is_Covered_Formal (Formal : Node_Id) return Boolean is
3512 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter)
3513 and then (Is_Elementary_Type (Etype (Formal))
3514 or else Is_Record_Type (Etype (Formal))
3515 or else Is_Array_Type (Etype (Formal)));
3516 end Is_Covered_Formal;
3519 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then
3523 -- Exclude calls rewritten as enumeration literals
3525 if Nkind (N) not in N_Subprogram_Call
3526 and then Nkind (N) /= N_Entry_Call_Statement
3531 -- If a call C has two or more parameters of mode in out or out that are
3532 -- of an elementary type, then the call is legal only if for each name
3533 -- N that is passed as a parameter of mode in out or out to the call C,
3534 -- there is no other name among the other parameters of mode in out or
3535 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3537 -- If appropriate warning switch is set, we also report warnings on
3538 -- overlapping parameters that are record types or array types.
3540 Form1 := First_Formal (Subp);
3541 Act1 := First_Actual (N);
3542 while Present (Form1) and then Present (Act1) loop
3543 if Is_Covered_Formal (Form1) then
3544 Form2 := First_Formal (Subp);
3545 Act2 := First_Actual (N);
3546 while Present (Form2) and then Present (Act2) loop
3548 and then Is_Covered_Formal (Form2)
3549 and then Refer_Same_Object (Act1, Act2)
3551 -- Guard against previous errors
3554 or else No (Etype (Act1))
3555 or else No (Etype (Act2))
3559 -- If the actual is a function call in prefix notation,
3560 -- there is no real overlap.
3562 elsif Nkind (Act2) = N_Function_Call then
3565 -- If type is not by-copy, assume that aliasing is intended
3568 Present (Underlying_Type (Etype (Form1)))
3570 (Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3572 Convention (Underlying_Type (Etype (Form1))) =
3573 Convention_Ada_Pass_By_Reference)
3577 -- Under Ada 2012 we only report warnings on overlapping
3578 -- arrays and record types if switch is set.
3580 elsif Ada_Version >= Ada_2012
3581 and then not Is_Elementary_Type (Etype (Form1))
3582 and then not Warn_On_Overlap
3586 -- Here we may need to issue overlap message
3591 -- Overlap checking is an error only in Ada 2012. For
3592 -- earlier versions of Ada, this is a warning.
3594 Ada_Version < Ada_2012
3596 -- Overlap is only illegal in Ada 2012 in the case of
3597 -- elementary types (passed by copy). For other types,
3598 -- we always have a warning in all Ada versions.
3600 or else not Is_Elementary_Type (Etype (Form1))
3602 -- Finally, debug flag -gnatd.E changes the error to a
3603 -- warning even in Ada 2012 mode.
3605 or else Error_To_Warning;
3612 -- Find matching actual
3614 Act := First_Actual (N);
3615 Form := First_Formal (Subp);
3616 while Act /= Act2 loop
3621 if Is_Elementary_Type (Etype (Act1))
3622 and then Ekind (Form2) = E_In_Parameter
3624 null; -- No real aliasing
3626 elsif Is_Elementary_Type (Etype (Act2))
3627 and then Ekind (Form2) = E_In_Parameter
3631 -- If the call was written in prefix notation, and
3632 -- thus its prefix before rewriting was a selected
3633 -- component, count only visible actuals in the call.
3635 elsif Is_Entity_Name (First_Actual (N))
3636 and then Nkind (Original_Node (N)) = Nkind (N)
3637 and then Nkind (Name (Original_Node (N))) =
3638 N_Selected_Component
3640 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3642 Entity (Prefix (Name (Original_Node (N)))) =
3643 Entity (First_Actual (N))
3645 if Act1 = First_Actual (N) then
3647 ("<<`IN OUT` prefix overlaps with "
3648 & "actual for&", Act1, Form);
3651 -- For greater clarity, give name of formal
3653 Error_Msg_Node_2 := Form;
3655 ("<<writable actual for & overlaps with "
3656 & "actual for&", Act1, Form);
3660 -- For greater clarity, give name of formal
3662 Error_Msg_Node_2 := Form;
3664 -- This is one of the messages
3667 ("<<writable actual for & overlaps with "
3668 & "actual for&", Act1, Form1);
3676 Next_Formal (Form2);
3681 Next_Formal (Form1);
3684 end Warn_On_Overlapping_Actuals;
3686 ------------------------------
3687 -- Warn_On_Suspicious_Index --
3688 ------------------------------
3690 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3693 -- Set to lower bound for a suspicious type
3696 -- Entity for array reference
3701 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3702 -- Tests to see if Typ is a type for which we may have a suspicious
3703 -- index, namely an unconstrained array type, whose lower bound is
3704 -- either zero or one. If so, True is returned, and Low_Bound is set
3705 -- to this lower bound. If not, False is returned, and Low_Bound is
3706 -- undefined on return.
3708 -- For now, we limit this to standard string types, so any other
3709 -- unconstrained types return False. We may change our minds on this
3710 -- later on, but strings seem the most important case.
3712 procedure Test_Suspicious_Index;
3713 -- Test if index is of suspicious type and if so, generate warning
3715 ------------------------
3716 -- Is_Suspicious_Type --
3717 ------------------------
3719 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3723 if Is_Array_Type (Typ)
3724 and then not Is_Constrained (Typ)
3725 and then Number_Dimensions (Typ) = 1
3726 and then Is_Standard_String_Type (Typ)
3727 and then not Has_Warnings_Off (Typ)
3729 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3731 if Compile_Time_Known_Value (LB) then
3732 Low_Bound := Expr_Value (LB);
3733 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3738 end Is_Suspicious_Type;
3740 ---------------------------
3741 -- Test_Suspicious_Index --
3742 ---------------------------
3744 procedure Test_Suspicious_Index is
3746 function Length_Reference (N : Node_Id) return Boolean;
3747 -- Check if node N is of the form Name'Length
3750 -- Generate first warning line
3752 ----------------------
3753 -- Length_Reference --
3754 ----------------------
3756 function Length_Reference (N : Node_Id) return Boolean is
3757 R : constant Node_Id := Original_Node (N);
3760 Nkind (R) = N_Attribute_Reference
3761 and then Attribute_Name (R) = Name_Length
3762 and then Is_Entity_Name (Prefix (R))
3763 and then Entity (Prefix (R)) = Ent;
3764 end Length_Reference;
3772 Error_Msg_Uint_1 := Low_Bound;
3773 Error_Msg_FE -- CODEFIX
3774 ("?w?index for& may assume lower bound of^", X, Ent);
3777 -- Start of processing for Test_Suspicious_Index
3780 -- Nothing to do if subscript does not come from source (we don't
3781 -- want to give garbage warnings on compiler expanded code, e.g. the
3782 -- loops generated for slice assignments. Such junk warnings would
3783 -- be placed on source constructs with no subscript in sight).
3785 if not Comes_From_Source (Original_Node (X)) then
3789 -- Case where subscript is a constant integer
3791 if Nkind (X) = N_Integer_Literal then
3794 -- Case where original form of subscript is an integer literal
3796 if Nkind (Original_Node (X)) = N_Integer_Literal then
3797 if Intval (X) = Low_Bound then
3798 Error_Msg_FE -- CODEFIX
3799 ("\?w?suggested replacement: `&''First`", X, Ent);
3801 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3802 Error_Msg_FE -- CODEFIX
3803 ("\?w?suggested replacement: `&''First + ^`", X, Ent);
3807 -- Case where original form of subscript is more complex
3810 -- Build string X'First - 1 + expression where the expression
3811 -- is the original subscript. If the expression starts with "1
3812 -- + ", then the "- 1 + 1" is elided.
3814 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3815 Error_Msg_Strlen := 13;
3818 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3819 Tref : constant Source_Buffer_Ptr :=
3820 Source_Text (Get_Source_File_Index (Sref));
3821 -- Tref (Sref) is used to scan the subscript
3824 -- Parentheses counter when scanning subscript
3827 -- Tref (Sref) points to start of subscript
3829 -- Elide - 1 if subscript starts with 1 +
3831 if Tref (Sref .. Sref + 2) = "1 +" then
3832 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3835 elsif Tref (Sref .. Sref + 1) = "1+" then
3836 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3840 -- Now we will copy the subscript to the string buffer
3844 -- Count parens, exit if terminating right paren. Note
3845 -- check to ignore paren appearing as character literal.
3847 if Tref (Sref + 1) = '''
3849 Tref (Sref - 1) = '''
3853 if Tref (Sref) = '(' then
3855 elsif Tref (Sref) = ')' then
3861 -- Done if terminating double dot (slice case)
3864 and then (Tref (Sref .. Sref + 1) = ".."
3866 Tref (Sref .. Sref + 2) = " ..");
3868 -- Quit if we have hit EOF character, something wrong
3870 if Tref (Sref) = EOF then
3874 -- String literals are too much of a pain to handle
3876 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3880 -- If we have a 'Range reference, then this is a case
3881 -- where we cannot easily give a replacement. Don't try.
3883 if Tref (Sref .. Sref + 4) = "range"
3884 and then Tref (Sref - 1) < 'A'
3885 and then Tref (Sref + 5) < 'A'
3890 -- Else store next character
3892 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3893 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3896 -- If we get more than 40 characters then the expression
3897 -- is too long to copy, or something has gone wrong. In
3898 -- either case, just skip the attempt at a suggested fix.
3900 if Error_Msg_Strlen > 40 then
3906 -- Replacement subscript is now in string buffer
3908 Error_Msg_FE -- CODEFIX
3909 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent);
3912 -- Case where subscript is of the form X'Length
3914 elsif Length_Reference (X) then
3916 Error_Msg_Node_2 := Ent;
3918 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3921 -- Case where subscript is of the form X'Length - expression
3923 elsif Nkind (X) = N_Op_Subtract
3924 and then Length_Reference (Left_Opnd (X))
3927 Error_Msg_Node_2 := Ent;
3929 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3930 Left_Opnd (X), Ent);
3932 end Test_Suspicious_Index;
3934 -- Start of processing for Warn_On_Suspicious_Index
3937 -- Only process if warnings activated
3939 if Warn_On_Assumed_Low_Bound then
3941 -- Test if array is simple entity name
3943 if Is_Entity_Name (Name) then
3945 -- Test if array is parameter of unconstrained string type
3947 Ent := Entity (Name);
3951 and then Is_Suspicious_Type (Typ)
3952 and then not Low_Bound_Tested (Ent)
3954 Test_Suspicious_Index;
3958 end Warn_On_Suspicious_Index;
3960 -------------------------------
3961 -- Warn_On_Suspicious_Update --
3962 -------------------------------
3964 procedure Warn_On_Suspicious_Update (N : Node_Id) is
3965 Par : constant Node_Id := Parent (N);
3969 -- Only process if warnings activated
3971 if Warn_On_Suspicious_Contract then
3972 if Nkind_In (Par, N_Op_Eq, N_Op_Ne) then
3973 if N = Left_Opnd (Par) then
3974 Arg := Right_Opnd (Par);
3976 Arg := Left_Opnd (Par);
3979 if Same_Object (Prefix (N), Arg) then
3980 if Nkind (Par) = N_Op_Eq then
3982 ("suspicious equality test with modified version of "
3983 & "same object?T?", Par);
3986 ("suspicious inequality test with modified version of "
3987 & "same object?T?", Par);
3992 end Warn_On_Suspicious_Update;
3994 --------------------------------------
3995 -- Warn_On_Unassigned_Out_Parameter --
3996 --------------------------------------
3998 procedure Warn_On_Unassigned_Out_Parameter
3999 (Return_Node : Node_Id;
4000 Scope_Id : Entity_Id)
4006 -- Ignore if procedure or return statement does not come from source
4008 if not Comes_From_Source (Scope_Id)
4009 or else not Comes_From_Source (Return_Node)
4014 -- Loop through formals
4016 Form := First_Formal (Scope_Id);
4017 while Present (Form) loop
4019 -- We are only interested in OUT parameters that come from source
4020 -- and are never set in the source, and furthermore only in scalars
4021 -- since non-scalars generate too many false positives.
4023 if Ekind (Form) = E_Out_Parameter
4024 and then Never_Set_In_Source_Check_Spec (Form)
4025 and then Is_Scalar_Type (Etype (Form))
4026 and then not Present (Unset_Reference (Form))
4028 -- Before we issue the warning, an add ad hoc defence against the
4029 -- most common case of false positives with this warning which is
4030 -- the case where there is a Boolean OUT parameter that has been
4031 -- set, and whose meaning is "ignore the values of the other
4032 -- parameters". We can't of course reliably tell this case at
4033 -- compile time, but the following test kills a lot of false
4034 -- positives, without generating a significant number of false
4035 -- negatives (missed real warnings).
4037 Form2 := First_Formal (Scope_Id);
4038 while Present (Form2) loop
4039 if Ekind (Form2) = E_Out_Parameter
4040 and then Root_Type (Etype (Form2)) = Standard_Boolean
4041 and then not Never_Set_In_Source_Check_Spec (Form2)
4046 Next_Formal (Form2);
4049 -- Here all conditions are met, record possible unset reference
4051 Set_Unset_Reference (Form, Return_Node);
4056 end Warn_On_Unassigned_Out_Parameter;
4058 ---------------------------------
4059 -- Warn_On_Unreferenced_Entity --
4060 ---------------------------------
4062 procedure Warn_On_Unreferenced_Entity
4063 (Spec_E : Entity_Id;
4064 Body_E : Entity_Id := Empty)
4066 E : Entity_Id := Spec_E;
4069 if not Referenced_Check_Spec (E)
4070 and then not Has_Pragma_Unreferenced_Check_Spec (E)
4071 and then not Warnings_Off_Check_Spec (E)
4072 and then not Has_Junk_Name (Spec_E)
4073 and then not Is_Exported (Spec_E)
4078 -- Case of variable that is assigned but not read. We suppress
4079 -- the message if the variable is volatile, has an address
4080 -- clause, is aliased, or is a renaming, or is imported.
4082 if Referenced_As_LHS_Check_Spec (E)
4083 and then No (Address_Clause (E))
4084 and then not Is_Volatile (E)
4086 if Warn_On_Modified_Unread
4087 and then not Is_Imported (E)
4088 and then not Is_Aliased (E)
4089 and then No (Renamed_Object (E))
4091 if not Has_Pragma_Unmodified_Check_Spec (E) then
4092 Error_Msg_N -- CODEFIX
4093 ("?u?variable & is assigned but never read!", E);
4096 Set_Last_Assignment (E, Empty);
4099 -- Normal case of neither assigned nor read (exclude variables
4100 -- referenced as out parameters, since we already generated
4101 -- appropriate warnings at the call point in this case).
4103 elsif not Referenced_As_Out_Parameter (E) then
4105 -- We suppress the message for types for which a valid
4106 -- pragma Unreferenced_Objects has been given, otherwise
4107 -- we go ahead and give the message.
4109 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
4111 -- Distinguish renamed case in message
4113 if Present (Renamed_Object (E))
4114 and then Comes_From_Source (Renamed_Object (E))
4116 Error_Msg_N -- CODEFIX
4117 ("?u?renamed variable & is not referenced!", E);
4119 Error_Msg_N -- CODEFIX
4120 ("?u?variable & is not referenced!", E);
4126 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
4127 if Present (Renamed_Object (E))
4128 and then Comes_From_Source (Renamed_Object (E))
4130 Error_Msg_N -- CODEFIX
4131 ("?u?renamed constant & is not referenced!", E);
4133 Error_Msg_N -- CODEFIX
4134 ("?u?constant & is not referenced!", E);
4138 when E_In_Parameter |
4139 E_In_Out_Parameter =>
4141 -- Do not emit message for formals of a renaming, because
4142 -- they are never referenced explicitly.
4144 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /=
4145 N_Subprogram_Renaming_Declaration
4147 -- Suppress this message for an IN OUT parameter of a
4148 -- non-scalar type, since it is normal to have only an
4149 -- assignment in such a case.
4151 if Ekind (E) = E_In_Parameter
4152 or else not Referenced_As_LHS_Check_Spec (E)
4153 or else Is_Scalar_Type (Etype (E))
4155 if Present (Body_E) then
4159 if not Is_Trivial_Subprogram (Scope (E)) then
4160 Error_Msg_NE -- CODEFIX
4161 ("?u?formal parameter & is not referenced!",
4167 when E_Out_Parameter =>
4170 when E_Discriminant =>
4171 Error_Msg_N ("?u?discriminant & is not referenced!", E);
4173 when E_Named_Integer |
4175 Error_Msg_N -- CODEFIX
4176 ("?u?named number & is not referenced!", E);
4178 when Formal_Object_Kind =>
4179 Error_Msg_N -- CODEFIX
4180 ("?u?formal object & is not referenced!", E);
4182 when E_Enumeration_Literal =>
4183 Error_Msg_N -- CODEFIX
4184 ("?u?literal & is not referenced!", E);
4187 Error_Msg_N -- CODEFIX
4188 ("?u?function & is not referenced!", E);
4191 Error_Msg_N -- CODEFIX
4192 ("?u?procedure & is not referenced!", E);
4195 Error_Msg_N -- CODEFIX
4196 ("?u?package & is not referenced!", E);
4199 Error_Msg_N -- CODEFIX
4200 ("?u?exception & is not referenced!", E);
4203 Error_Msg_N -- CODEFIX
4204 ("?u?label & is not referenced!", E);
4206 when E_Generic_Procedure =>
4207 Error_Msg_N -- CODEFIX
4208 ("?u?generic procedure & is never instantiated!", E);
4210 when E_Generic_Function =>
4211 Error_Msg_N -- CODEFIX
4212 ("?u?generic function & is never instantiated!", E);
4215 Error_Msg_N -- CODEFIX
4216 ("?u?type & is not referenced!", E);
4219 Error_Msg_N -- CODEFIX
4220 ("?u?& is not referenced!", E);
4223 -- Kill warnings on the entity on which the message has been posted
4224 -- (nothing is posted on out parameters because back end might be
4225 -- able to uncover an uninitialized path, and warn accordingly).
4227 if Ekind (E) /= E_Out_Parameter then
4228 Set_Warnings_Off (E);
4231 end Warn_On_Unreferenced_Entity;
4233 --------------------------------
4234 -- Warn_On_Useless_Assignment --
4235 --------------------------------
4237 procedure Warn_On_Useless_Assignment
4239 N : Node_Id := Empty)
4244 function Check_Ref (N : Node_Id) return Traverse_Result;
4245 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4246 -- the entity in question is found.
4248 function Test_No_Refs is new Traverse_Func (Check_Ref);
4254 function Check_Ref (N : Node_Id) return Traverse_Result is
4256 -- Check reference to our identifier. We use name equality here
4257 -- because the exception handlers have not yet been analyzed. This
4258 -- is not quite right, but it really does not matter that we fail
4259 -- to output the warning in some obscure cases of name clashes.
4261 if Nkind (N) = N_Identifier and then Chars (N) = Chars (Ent) then
4268 -- Start of processing for Warn_On_Useless_Assignment
4271 -- Check if this is a case we want to warn on, a scalar or access
4272 -- variable with the last assignment field set, with warnings enabled,
4273 -- and which is not imported or exported. We also check that it is OK
4274 -- to capture the value. We are not going to capture any value, but
4275 -- the warning message depends on the same kind of conditions.
4277 if Is_Assignable (Ent)
4278 and then not Is_Return_Object (Ent)
4279 and then Present (Last_Assignment (Ent))
4280 and then not Is_Imported (Ent)
4281 and then not Is_Exported (Ent)
4282 and then Safe_To_Capture_Value (N, Ent)
4283 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
4284 and then not Has_Junk_Name (Ent)
4286 -- Before we issue the message, check covering exception handlers.
4287 -- Search up tree for enclosing statement sequences and handlers.
4289 P := Parent (Last_Assignment (Ent));
4290 while Present (P) loop
4292 -- Something is really wrong if we don't find a handled statement
4293 -- sequence, so just suppress the warning.
4296 Set_Last_Assignment (Ent, Empty);
4299 -- When we hit a package/subprogram body, issue warning and exit
4301 elsif Nkind (P) = N_Subprogram_Body
4302 or else Nkind (P) = N_Package_Body
4304 -- Case of assigned value never referenced
4308 LA : constant Node_Id := Last_Assignment (Ent);
4311 -- Don't give this for OUT and IN OUT formals, since
4312 -- clearly caller may reference the assigned value. Also
4313 -- never give such warnings for internal variables.
4315 if Ekind (Ent) = E_Variable
4316 and then not Is_Internal_Name (Chars (Ent))
4318 -- Give appropriate message, distinguishing between
4319 -- assignment statements and out parameters.
4321 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4322 N_Parameter_Association)
4325 ("?m?& modified by call, but value never "
4326 & "referenced", LA, Ent);
4329 Error_Msg_NE -- CODEFIX
4330 ("?m?useless assignment to&, value never "
4331 & "referenced!", LA, Ent);
4336 -- Case of assigned value overwritten
4340 LA : constant Node_Id := Last_Assignment (Ent);
4343 Error_Msg_Sloc := Sloc (N);
4345 -- Give appropriate message, distinguishing between
4346 -- assignment statements and out parameters.
4348 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4349 N_Parameter_Association)
4352 ("?m?& modified by call, but value overwritten #!",
4355 Error_Msg_NE -- CODEFIX
4356 ("?m?useless assignment to&, value overwritten #!",
4362 -- Clear last assignment indication and we are done
4364 Set_Last_Assignment (Ent, Empty);
4367 -- Enclosing handled sequence of statements
4369 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4371 -- Check exception handlers present
4373 if Present (Exception_Handlers (P)) then
4375 -- If we are not at the top level, we regard an inner
4376 -- exception handler as a decisive indicator that we should
4377 -- not generate the warning, since the variable in question
4378 -- may be accessed after an exception in the outer block.
4380 if Nkind (Parent (P)) /= N_Subprogram_Body
4381 and then Nkind (Parent (P)) /= N_Package_Body
4383 Set_Last_Assignment (Ent, Empty);
4386 -- Otherwise we are at the outer level. An exception
4387 -- handler is significant only if it references the
4388 -- variable in question, or if the entity in question
4389 -- is an OUT or IN OUT parameter, in which case
4390 -- the caller can reference it after the exception
4391 -- handler completes.
4394 if Is_Formal (Ent) then
4395 Set_Last_Assignment (Ent, Empty);
4399 X := First (Exception_Handlers (P));
4400 while Present (X) loop
4401 if Test_No_Refs (X) = Abandon then
4402 Set_Last_Assignment (Ent, Empty);
4416 end Warn_On_Useless_Assignment;
4418 ---------------------------------
4419 -- Warn_On_Useless_Assignments --
4420 ---------------------------------
4422 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4426 Process_Deferred_References;
4428 if Warn_On_Modified_Unread
4429 and then In_Extended_Main_Source_Unit (E)
4431 Ent := First_Entity (E);
4432 while Present (Ent) loop
4433 Warn_On_Useless_Assignment (Ent);
4437 end Warn_On_Useless_Assignments;
4439 -----------------------------
4440 -- Warnings_Off_Check_Spec --
4441 -----------------------------
4443 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4445 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4447 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4448 -- to mess with flags on both entities.
4450 return Has_Warnings_Off (E)
4452 Has_Warnings_Off (Spec_Entity (E));
4455 return Has_Warnings_Off (E);
4457 end Warnings_Off_Check_Spec;