1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2008, 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 Namet; use Namet;
34 with Nlists; use Nlists;
36 with Rtsfind; use Rtsfind;
38 with Sem_Ch8; use Sem_Ch8;
39 with Sem_Aux; use Sem_Aux;
40 with Sem_Eval; use Sem_Eval;
41 with Sem_Util; use Sem_Util;
42 with Sinfo; use Sinfo;
43 with Sinput; use Sinput;
44 with Snames; use Snames;
45 with Stand; use Stand;
46 with Stringt; use Stringt;
47 with Uintp; use Uintp;
49 package body Sem_Warn is
51 -- The following table collects Id's of entities that are potentially
52 -- unreferenced. See Check_Unset_Reference for further details.
53 -- ??? Check_Unset_Reference has zero information about this table.
55 package Unreferenced_Entities is new Table.Table (
56 Table_Component_Type => Entity_Id,
57 Table_Index_Type => Nat,
59 Table_Initial => Alloc.Unreferenced_Entities_Initial,
60 Table_Increment => Alloc.Unreferenced_Entities_Increment,
61 Table_Name => "Unreferenced_Entities");
63 -- The following table collects potential warnings for IN OUT parameters
64 -- that are referenced but not modified. These warnings are processed when
65 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
66 -- The reason that we defer output of these messages is that we want to
67 -- detect the case where the relevant procedure is used as a generic actual
68 -- in an instantiation, since we suppress the warnings in this case. The
69 -- flag Used_As_Generic_Actual will be set in this case, but only at the
70 -- point of usage. Similarly, we suppress the message if the address of the
71 -- procedure is taken, where the flag Address_Taken may be set later.
73 package In_Out_Warnings is new Table.Table (
74 Table_Component_Type => Entity_Id,
75 Table_Index_Type => Nat,
77 Table_Initial => Alloc.In_Out_Warnings_Initial,
78 Table_Increment => Alloc.In_Out_Warnings_Increment,
79 Table_Name => "In_Out_Warnings");
81 --------------------------------------------------------
82 -- Handling of Warnings Off, Unmodified, Unreferenced --
83 --------------------------------------------------------
85 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
86 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
87 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
89 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
90 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
91 -- must follow some important rules.
93 -- Call these functions as late as possible, after completing all other
94 -- tests, just before the warnings is given. For example, don't write:
96 -- if not Has_Warnings_Off (E)
97 -- and then some-other-predicate-on-E then ..
99 -- Instead the following is preferred
101 -- if some-other-predicate-on-E
102 -- and then Has_Warnings_Off (E)
104 -- This way if some-other-predicate is false, we avoid a false indication
105 -- that a Warnings (Off,E) pragma was useful in preventing a warning.
107 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
108 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
109 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
110 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
111 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
112 -- and so a subsequent test is not needed anyway (though it is harmless).
114 -----------------------
115 -- Local Subprograms --
116 -----------------------
118 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean;
119 -- This returns true if the entity E is declared within a generic package.
120 -- The point of this is to detect variables which are not assigned within
121 -- the generic, but might be assigned outside the package for any given
122 -- instance. These are cases where we leave the warnings to be posted for
123 -- the instance, when we will know more.
125 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id;
126 -- If E is a parameter entity for a subprogram body, then this function
127 -- returns the corresponding spec entity, if not, E is returned unchanged.
129 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean;
130 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
131 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
132 -- a body formal, the setting of the flag in the corresponding spec is
133 -- also checked (and True returned if either flag is True).
135 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean;
136 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
137 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
138 -- a body formal, the setting of the flag in the corresponding spec is
139 -- also checked (and True returned if either flag is True).
141 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean;
142 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
143 -- this is simply the setting of the flag Never_Set_In_Source. If E is
144 -- a body formal, the setting of the flag in the corresponding spec is
145 -- also checked (and False returned if either flag is False).
147 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
148 -- This function traverses the expression tree represented by the node N
149 -- and determines if any sub-operand is a reference to an entity for which
150 -- the Warnings_Off flag is set. True is returned if such an entity is
151 -- encountered, and False otherwise.
153 function Referenced_Check_Spec (E : Entity_Id) return Boolean;
154 -- Tests Referenced status for entity E. If E is not a formal, this is
155 -- simply the setting of the flag Referenced. If E is a body formal, the
156 -- setting of the flag in the corresponding spec is also checked (and True
157 -- returned if either flag is True).
159 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean;
160 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
161 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
162 -- formal, the setting of the flag in the corresponding spec is also
163 -- checked (and True returned if either flag is True).
165 function Referenced_As_Out_Parameter_Check_Spec
166 (E : Entity_Id) return Boolean;
167 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
168 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
169 -- is a body formal, the setting of the flag in the corresponding spec is
170 -- also checked (and True returned if either flag is True).
172 procedure Warn_On_Unreferenced_Entity
174 Body_E : Entity_Id := Empty);
175 -- Output warnings for unreferenced entity E. For the case of an entry
176 -- formal, Body_E is the corresponding body entity for a particular
177 -- accept statement, and the message is posted on Body_E. In all other
178 -- cases, Body_E is ignored and must be Empty.
180 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean;
181 -- Returns True if Warnings_Off is set for the entity E or (in the case
182 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
184 --------------------------
185 -- Check_Code_Statement --
186 --------------------------
188 procedure Check_Code_Statement (N : Node_Id) is
190 -- If volatile, nothing to worry about
192 if Is_Asm_Volatile (N) then
196 -- Warn if no input or no output
198 Setup_Asm_Inputs (N);
200 if No (Asm_Input_Value) then
202 ("?code statement with no inputs should usually be Volatile!", N);
206 Setup_Asm_Outputs (N);
208 if No (Asm_Output_Variable) then
210 ("?code statement with no outputs should usually be Volatile!", N);
214 -- Check multiple code statements in a row
216 if Is_List_Member (N)
217 and then Present (Prev (N))
218 and then Nkind (Prev (N)) = N_Code_Statement
221 ("?code statements in sequence should usually be Volatile!", N);
223 ("\?(suggest using template with multiple instructions)!", N);
225 end Check_Code_Statement;
227 ---------------------------------
228 -- Check_Infinite_Loop_Warning --
229 ---------------------------------
231 -- The case we look for is a while loop which tests a local variable, where
232 -- there is no obvious direct or possible indirect update of the variable
233 -- within the body of the loop.
235 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
236 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
238 Ref : Node_Id := Empty;
239 -- Reference in iteration scheme to variable that may not be modified in
240 -- loop, indicating a possible infinite loop.
242 Var : Entity_Id := Empty;
243 -- Corresponding entity (entity of Ref)
245 procedure Find_Var (N : Node_Id);
246 -- Inspect condition to see if it depends on a single entity reference.
247 -- If so, Ref is set to point to the reference node, and Var is set to
248 -- the referenced Entity.
250 function Has_Indirection (T : Entity_Id) return Boolean;
251 -- If the controlling variable is an access type, or is a record type
252 -- with access components, assume that it is changed indirectly and
253 -- suppress the warning. As a concession to low-level programming, in
254 -- particular within Declib, we also suppress warnings on a record
255 -- type that contains components of type Address or Short_Address.
257 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
258 -- Given an entity name, see if the name appears to have something to
259 -- do with I/O or network stuff, and if so, return True. Used to kill
260 -- some false positives on a heuristic basis that such functions will
261 -- likely have some strange side effect dependencies. A rather funny
262 -- kludge, but warning messages are in the heuristics business.
264 function Test_Ref (N : Node_Id) return Traverse_Result;
265 -- Test for reference to variable in question. Returns Abandon if
266 -- matching reference found.
268 function Find_Ref is new Traverse_Func (Test_Ref);
269 -- Function to traverse body of procedure. Returns Abandon if matching
276 procedure Find_Var (N : Node_Id) is
278 -- Condition is a direct variable reference
280 if Is_Entity_Name (N) then
284 -- Case of condition is a comparison with compile time known value
286 elsif Nkind (N) in N_Op_Compare then
287 if Compile_Time_Known_Value (Right_Opnd (N)) then
288 Find_Var (Left_Opnd (N));
290 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
291 Find_Var (Right_Opnd (N));
293 -- Ignore any other comparison
299 -- If condition is a negation, check its operand
301 elsif Nkind (N) = N_Op_Not then
302 Find_Var (Right_Opnd (N));
304 -- Case of condition is function call
306 elsif Nkind (N) = N_Function_Call then
308 -- Forget it if function name is not entity, who knows what
309 -- we might be calling?
311 if not Is_Entity_Name (Name (N)) then
314 -- Forget it if function name is suspicious. A strange test
315 -- but warning generation is in the heuristics business!
317 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
320 -- Forget it if warnings are suppressed on function entity
322 elsif Has_Warnings_Off (Entity (Name (N))) then
326 -- OK, see if we have one argument
329 PA : constant List_Id := Parameter_Associations (N);
332 -- One argument, so check the argument
335 and then List_Length (PA) = 1
337 if Nkind (First (PA)) = N_Parameter_Association then
338 Find_Var (Explicit_Actual_Parameter (First (PA)));
340 Find_Var (First (PA));
350 -- Any other kind of node is not something we warn for
357 ---------------------
358 -- Has_Indirection --
359 ---------------------
361 function Has_Indirection (T : Entity_Id) return Boolean is
366 if Is_Access_Type (T) then
369 elsif Is_Private_Type (T)
370 and then Present (Full_View (T))
371 and then Is_Access_Type (Full_View (T))
375 elsif Is_Record_Type (T) then
378 elsif Is_Private_Type (T)
379 and then Present (Full_View (T))
380 and then Is_Record_Type (Full_View (T))
382 Rec := Full_View (T);
387 Comp := First_Component (Rec);
388 while Present (Comp) loop
389 if Is_Access_Type (Etype (Comp))
390 or else Is_Descendent_Of_Address (Etype (Comp))
395 Next_Component (Comp);
401 ---------------------------------
402 -- Is_Suspicious_Function_Name --
403 ---------------------------------
405 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
408 function Substring_Present (S : String) return Boolean;
409 -- Returns True if name buffer has given string delimited by non-
410 -- alphabetic characters or by end of string. S is lower case.
412 -----------------------
413 -- Substring_Present --
414 -----------------------
416 function Substring_Present (S : String) return Boolean is
417 Len : constant Natural := S'Length;
420 for J in 1 .. Name_Len - (Len - 1) loop
421 if Name_Buffer (J .. J + (Len - 1)) = S
424 or else Name_Buffer (J - 1) not in 'a' .. 'z')
427 or else Name_Buffer (J + Len) not in 'a' .. 'z')
434 end Substring_Present;
436 -- Start of processing for Is_Suspicious_Function_Name
440 while Present (S) and then S /= Standard_Standard loop
441 Get_Name_String (Chars (S));
443 if Substring_Present ("io")
444 or else Substring_Present ("file")
445 or else Substring_Present ("network")
454 end Is_Suspicious_Function_Name;
460 function Test_Ref (N : Node_Id) return Traverse_Result is
462 -- Waste of time to look at iteration scheme
467 -- Direct reference to variable in question
469 elsif Is_Entity_Name (N)
470 and then Present (Entity (N))
471 and then Entity (N) = Var
473 -- If this is an Lvalue, then definitely abandon, since
474 -- this could be a direct modification of the variable.
476 if May_Be_Lvalue (N) then
480 -- If we appear in the context of a procedure call, then also
481 -- abandon, since there may be issues of non-visible side
482 -- effects going on in the call.
491 exit when P = Loop_Statement;
493 if Nkind (P) = N_Procedure_Call_Statement then
499 -- Reference to variable renaming variable in question
501 elsif Is_Entity_Name (N)
502 and then Present (Entity (N))
503 and then Ekind (Entity (N)) = E_Variable
504 and then Present (Renamed_Object (Entity (N)))
505 and then Is_Entity_Name (Renamed_Object (Entity (N)))
506 and then Entity (Renamed_Object (Entity (N))) = Var
507 and then May_Be_Lvalue (N)
511 -- Call to subprogram
513 elsif Nkind (N) = N_Procedure_Call_Statement
514 or else Nkind (N) = N_Function_Call
516 -- If subprogram is within the scope of the entity we are dealing
517 -- with as the loop variable, then it could modify this parameter,
518 -- so we abandon in this case. In the case of a subprogram that is
519 -- not an entity we also abandon. The check for no entity being
520 -- present is a defense against previous errors.
522 if not Is_Entity_Name (Name (N))
523 or else No (Entity (Name (N)))
524 or else Scope_Within (Entity (Name (N)), Scope (Var))
530 -- All OK, continue scan
535 -- Start of processing for Check_Infinite_Loop_Warning
538 -- We need a while iteration with no condition actions. Conditions
539 -- actions just make things too complicated to get the warning right.
542 or else No (Condition (Iter))
543 or else Present (Condition_Actions (Iter))
544 or else Debug_Flag_Dot_W
549 -- Initial conditions met, see if condition is of right form
551 Find_Var (Condition (Iter));
553 -- Nothing to do if local variable from source not found
556 or else Ekind (Var) /= E_Variable
557 or else Is_Library_Level_Entity (Var)
558 or else not Comes_From_Source (Var)
562 -- Nothing to do if there is some indirection involved (assume that the
563 -- designated variable might be modified in some way we don't see).
565 elsif Has_Indirection (Etype (Var)) then
568 -- Same sort of thing for volatile variable, might be modified by
569 -- some other task or by the operating system in some way.
571 elsif Is_Volatile (Var) then
575 -- Filter out case of original statement sequence starting with delay.
576 -- We assume this is a multi-tasking program and that the condition
577 -- is affected by other threads (some kind of busy wait).
580 Fstm : constant Node_Id :=
581 Original_Node (First (Statements (Loop_Statement)));
583 if Nkind (Fstm) = N_Delay_Relative_Statement
584 or else Nkind (Fstm) = N_Delay_Until_Statement
590 -- We have a variable reference of the right form, now we scan the loop
591 -- body to see if it looks like it might not be modified
593 if Find_Ref (Loop_Statement) = OK then
595 ("?variable& is not modified in loop body!", Ref, Var);
597 ("\?possible infinite loop!", Ref);
599 end Check_Infinite_Loop_Warning;
601 ----------------------
602 -- Check_References --
603 ----------------------
605 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
612 Accept_Statement : Node_Id) return Entity_Id;
613 -- For an entry formal entity from an entry declaration, find the
614 -- corresponding body formal from the given accept statement.
616 function Missing_Subunits return Boolean;
617 -- We suppress warnings when there are missing subunits, because this
618 -- may generate too many false positives: entities in a parent may only
619 -- be referenced in one of the subunits. We make an exception for
620 -- subunits that contain no other stubs.
622 procedure Output_Reference_Error (M : String);
623 -- Used to output an error message. Deals with posting the error on the
624 -- body formal in the accept case.
626 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
627 -- This is true if the entity in question is potentially referenceable
628 -- from another unit. This is true for entities in packages that are at
629 -- the library level.
631 function Warnings_Off_E1 return Boolean;
632 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
633 -- or for the base type of E1T.
641 Accept_Statement : Node_Id) return Entity_Id
643 Body_Param : Node_Id;
647 -- Loop to find matching parameter in accept statement
649 Body_Param := First (Parameter_Specifications (Accept_Statement));
650 while Present (Body_Param) loop
651 Body_E := Defining_Identifier (Body_Param);
653 if Chars (Body_E) = Chars (E) then
660 -- Should never fall through, should always find a match
665 ----------------------
666 -- Missing_Subunits --
667 ----------------------
669 function Missing_Subunits return Boolean is
673 if not Unloaded_Subunits then
675 -- Normal compilation, all subunits are present
679 elsif E /= Main_Unit_Entity then
681 -- No warnings on a stub that is not the main unit
685 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
686 D := First (Declarations (Unit_Declaration_Node (E)));
687 while Present (D) loop
689 -- No warnings if the proper body contains nested stubs
691 if Nkind (D) in N_Body_Stub then
701 -- Missing stubs elsewhere
705 end Missing_Subunits;
707 ----------------------------
708 -- Output_Reference_Error --
709 ----------------------------
711 procedure Output_Reference_Error (M : String) is
713 -- Never issue messages for internal names
715 if Is_Internal_Name (Chars (E1)) then
719 -- Don't output message for IN OUT formal unless we have the warning
720 -- flag specifically set. It is a bit odd to distinguish IN OUT
721 -- formals from other cases. This distinction is historical in
722 -- nature. Warnings for IN OUT formals were added fairly late.
724 if Ekind (E1) = E_In_Out_Parameter
725 and then not Check_Unreferenced_Formals
730 -- Other than accept case, post error on defining identifier
735 -- Accept case, find body formal to post the message
738 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
741 end Output_Reference_Error;
743 ----------------------------
744 -- Publicly_Referenceable --
745 ----------------------------
747 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
752 -- A formal parameter is never referenceable outside the body of its
753 -- subprogram or entry.
755 if Is_Formal (Ent) then
759 -- Examine parents to look for a library level package spec. But if
760 -- we find a body or block or other similar construct along the way,
761 -- we cannot be referenced.
768 -- If we get to top of tree, then publicly referenceable
773 -- If we reach a generic package declaration, then always
774 -- consider this referenceable, since any instantiation will
775 -- have access to the entities in the generic package. Note
776 -- that the package itself may not be instantiated, but then
777 -- we will get a warning for the package entity.
779 -- Note that generic formal parameters are themselves not
780 -- publicly referenceable in an instance, and warnings on them
783 when N_Generic_Package_Declaration =>
785 not Is_List_Member (Prev)
786 or else List_Containing (Prev)
787 /= Generic_Formal_Declarations (P);
789 -- Similarly, the generic formals of a generic subprogram are
792 when N_Generic_Subprogram_Declaration =>
793 if Is_List_Member (Prev)
794 and then List_Containing (Prev) =
795 Generic_Formal_Declarations (P)
802 -- If we reach a subprogram body, entity is not referenceable
803 -- unless it is the defining entity of the body. This will
804 -- happen, e.g. when a function is an attribute renaming that
805 -- is rewritten as a body.
807 when N_Subprogram_Body =>
808 if Ent /= Defining_Entity (P) then
814 -- If we reach any other body, definitely not referenceable
816 when N_Package_Body |
824 -- For all other cases, keep looking up tree
831 end Publicly_Referenceable;
833 ---------------------
834 -- Warnings_Off_E1 --
835 ---------------------
837 function Warnings_Off_E1 return Boolean is
839 return Has_Warnings_Off (E1T)
840 or else Has_Warnings_Off (Base_Type (E1T))
841 or else Warnings_Off_Check_Spec (E1);
844 -- Start of processing for Check_References
847 -- No messages if warnings are suppressed, or if we have detected any
848 -- real errors so far (this last check avoids junk messages resulting
849 -- from errors, e.g. a subunit that is not loaded).
851 if Warning_Mode = Suppress
852 or else Serious_Errors_Detected /= 0
857 -- We also skip the messages if any subunits were not loaded (see
858 -- comment in Sem_Ch10 to understand how this is set, and why it is
859 -- necessary to suppress the warnings in this case).
861 if Missing_Subunits then
865 -- Otherwise loop through entities, looking for suspicious stuff
867 E1 := First_Entity (E);
868 while Present (E1) loop
871 -- We are only interested in source entities. We also don't issue
872 -- warnings within instances, since the proper place for such
873 -- warnings is on the template when it is compiled.
875 if Comes_From_Source (E1)
876 and then Instantiation_Location (Sloc (E1)) = No_Location
878 -- We are interested in variables and out/in-out parameters, but
879 -- we exclude protected types, too complicated to worry about.
881 if Ekind (E1) = E_Variable
883 ((Ekind (E1) = E_Out_Parameter
884 or else Ekind (E1) = E_In_Out_Parameter)
885 and then not Is_Protected_Type (Current_Scope))
887 -- Case of an unassigned variable
889 -- First gather any Unset_Reference indication for E1. In the
890 -- case of a parameter, it is the Spec_Entity that is relevant.
892 if Ekind (E1) = E_Out_Parameter
893 and then Present (Spec_Entity (E1))
895 UR := Unset_Reference (Spec_Entity (E1));
897 UR := Unset_Reference (E1);
900 -- Special processing for access types
903 and then Is_Access_Type (E1T)
905 -- For access types, the only time we made a UR entry was
906 -- for a dereference, and so we post the appropriate warning
907 -- here (note that the dereference may not be explicit in
908 -- the source, for example in the case of a dispatching call
909 -- with an anonymous access controlling formal, or of an
910 -- assignment of a pointer involving discriminant check
911 -- on the designated object).
913 if not Warnings_Off_E1 then
914 Error_Msg_NE ("?& may be null!", UR, E1);
919 -- Case of variable that could be a constant. Note that we
920 -- never signal such messages for generic package entities,
921 -- since a given instance could have modifications outside
924 elsif Warn_On_Constant
925 and then (Ekind (E1) = E_Variable
926 and then Has_Initial_Value (E1))
927 and then Never_Set_In_Source_Check_Spec (E1)
928 and then not Address_Taken (E1)
929 and then not Generic_Package_Spec_Entity (E1)
931 -- A special case, if this variable is volatile and not
932 -- imported, it is not helpful to tell the programmer
933 -- to mark the variable as constant, since this would be
934 -- illegal by virtue of RM C.6(13).
936 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
937 and then not Is_Imported (E1)
940 ("?& is not modified, volatile has no effect!", E1);
942 -- Another special case, Exception_Occurrence, this catches
943 -- the case of exception choice (and a bit more too, but not
944 -- worth doing more investigation here).
946 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
949 -- Here we give the warning if referenced and no pragma
950 -- Unreferenced or Unmodified is present.
955 if Ekind (E1) = E_Variable then
956 if Referenced_Check_Spec (E1)
957 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
958 and then not Has_Pragma_Unmodified_Check_Spec (E1)
960 if not Warnings_Off_E1 then
962 ("?& is not modified, "
963 & "could be declared constant!",
970 -- Other cases of a variable or parameter never set in source
972 elsif Never_Set_In_Source_Check_Spec (E1)
974 -- No warning if warning for this case turned off
976 and then Warn_On_No_Value_Assigned
978 -- No warning if address taken somewhere
980 and then not Address_Taken (E1)
982 -- No warning if explicit initial value
984 and then not Has_Initial_Value (E1)
986 -- No warning for generic package spec entities, since we
987 -- might set them in a child unit or something like that
989 and then not Generic_Package_Spec_Entity (E1)
991 -- No warning if fully initialized type, except that for
992 -- this purpose we do not consider access types to qualify
993 -- as fully initialized types (relying on an access type
994 -- variable being null when it is never set is a bit odd!)
996 -- Also we generate warning for an out parameter that is
997 -- never referenced, since again it seems odd to rely on
998 -- default initialization to set an out parameter value.
1000 and then (Is_Access_Type (E1T)
1001 or else Ekind (E1) = E_Out_Parameter
1002 or else not Is_Fully_Initialized_Type (E1T))
1004 -- Do not output complaint about never being assigned a
1005 -- value if a pragma Unmodified applies to the variable
1006 -- we are examining, or if it is a parameter, if there is
1007 -- a pragma Unreferenced for the corresponding spec, of
1008 -- if the type is marked as having unreferenced objects.
1009 -- The last is a little peculiar, but better too few than
1010 -- too many warnings in this situation.
1012 if Has_Pragma_Unreferenced_Objects (E1T)
1013 or else Has_Pragma_Unmodified_Check_Spec (E1)
1017 -- IN OUT parameter case where parameter is referenced. We
1018 -- separate this out, since this is the case where we delay
1019 -- output of the warning until more information is available
1020 -- (about use in an instantiation or address being taken).
1022 elsif Ekind (E1) = E_In_Out_Parameter
1023 and then Referenced_Check_Spec (E1)
1025 -- Suppress warning if private type, and the procedure
1026 -- has a separate declaration in a different unit. This
1027 -- is the case where the client of a package sees only
1028 -- the private type, and it it may be quite reasonable
1029 -- for the logical view to be in out, even if the
1030 -- implementation ends up using access types or some
1031 -- other method to achieve the local effect of a
1032 -- modification. On the other hand if the spec and body
1033 -- are in the same unit, we are in the package body and
1034 -- there we have less excuse for a junk IN OUT parameter.
1036 if Has_Private_Declaration (E1T)
1037 and then Present (Spec_Entity (E1))
1038 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1042 -- Suppress warning for any parameter of a dispatching
1043 -- operation, since it is quite reasonable to have an
1044 -- operation that is overridden, and for some subclasses
1045 -- needs the formal to be IN OUT and for others happens
1046 -- not to assign it.
1048 elsif Is_Dispatching_Operation
1049 (Scope (Goto_Spec_Entity (E1)))
1053 -- Suppress warning if composite type containing any
1054 -- access element component, since the logical effect
1055 -- of modifying a parameter may be achieved by modifying
1056 -- a referenced entity.
1058 elsif Is_Composite_Type (E1T)
1059 and then Has_Access_Values (E1T)
1063 -- OK, looks like warning for an IN OUT parameter that
1064 -- could be IN makes sense, but we delay the output of
1065 -- the warning, pending possibly finding out later on
1066 -- that the associated subprogram is used as a generic
1067 -- actual, or its address/access is taken. In these two
1068 -- cases, we suppress the warning because the context may
1069 -- force use of IN OUT, even if in this particular case
1070 -- the formal is not modified.
1073 In_Out_Warnings.Append (E1);
1076 -- Other cases of formals
1078 elsif Is_Formal (E1) then
1079 if not Is_Trivial_Subprogram (Scope (E1)) then
1080 if Referenced_Check_Spec (E1) then
1081 if not Has_Pragma_Unmodified_Check_Spec (E1)
1082 and then not Warnings_Off_E1
1084 Output_Reference_Error
1085 ("?formal parameter& is read but "
1086 & "never assigned!");
1089 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1090 and then not Warnings_Off_E1
1092 Output_Reference_Error
1093 ("?formal parameter& is not referenced!");
1100 if Referenced (E1) then
1101 if not Has_Unmodified (E1)
1102 and then not Warnings_Off_E1
1104 Output_Reference_Error
1105 ("?variable& is read but never assigned!");
1108 elsif not Has_Unreferenced (E1)
1109 and then not Warnings_Off_E1
1111 Output_Reference_Error
1112 ("?variable& is never read and never assigned!");
1115 -- Deal with special case where this variable is hidden
1116 -- by a loop variable.
1118 if Ekind (E1) = E_Variable
1119 and then Present (Hiding_Loop_Variable (E1))
1120 and then not Warnings_Off_E1
1123 ("?for loop implicitly declares loop variable!",
1124 Hiding_Loop_Variable (E1));
1126 Error_Msg_Sloc := Sloc (E1);
1128 ("\?declaration hides & declared#!",
1129 Hiding_Loop_Variable (E1));
1136 -- Check for unset reference
1138 if Warn_On_No_Value_Assigned and then Present (UR) then
1140 -- For other than access type, go back to original node to
1141 -- deal with case where original unset reference has been
1142 -- rewritten during expansion.
1144 -- In some cases, the original node may be a type conversion
1145 -- or qualification, and in this case we want the object
1148 UR := Original_Node (UR);
1149 while Nkind (UR) = N_Type_Conversion
1150 or else Nkind (UR) = N_Qualified_Expression
1152 UR := Expression (UR);
1155 -- Here we issue the warning, all checks completed
1157 -- If we have a return statement, this was a case of an OUT
1158 -- parameter not being set at the time of the return. (Note:
1159 -- it can't be N_Extended_Return_Statement, because those
1160 -- are only for functions, and functions do not allow OUT
1163 if not Is_Trivial_Subprogram (Scope (E1)) then
1164 if Nkind (UR) = N_Simple_Return_Statement
1165 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1167 if not Warnings_Off_E1 then
1169 ("?OUT parameter& not set before return", UR, E1);
1172 -- If the unset reference is a selected component
1173 -- prefix from source, mention the component as well.
1174 -- If the selected component comes from expansion, all
1175 -- we know is that the entity is not fully initialized
1176 -- at the point of the reference. Locate a random
1177 -- uninitialized component to get a better message.
1179 elsif Nkind (Parent (UR)) = N_Selected_Component then
1180 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1182 if not Comes_From_Source (Parent (UR)) then
1187 Comp := First_Entity (E1T);
1188 while Present (Comp) loop
1189 if Ekind (Comp) = E_Component
1190 and then Nkind (Parent (Comp)) =
1191 N_Component_Declaration
1192 and then No (Expression (Parent (Comp)))
1194 Error_Msg_Node_2 := Comp;
1203 -- Issue proper warning. This is a case of referencing
1204 -- a variable before it has been explicitly assigned.
1205 -- For access types, UR was only set for dereferences,
1206 -- so the issue is that the value may be null.
1208 if not Is_Trivial_Subprogram (Scope (E1)) then
1209 if not Warnings_Off_E1 then
1210 if Is_Access_Type (Etype (Parent (UR))) then
1211 Error_Msg_N ("?`&.&` may be null!", UR);
1214 ("?`&.&` may be referenced before "
1215 & "it has a value!", UR);
1220 -- All other cases of unset reference active
1222 elsif not Warnings_Off_E1 then
1224 ("?& may be referenced before it has a value!",
1233 -- Then check for unreferenced entities. Note that we are only
1234 -- interested in entities whose Referenced flag is not set.
1236 if not Referenced_Check_Spec (E1)
1238 -- If Referenced_As_LHS is set, then that's still interesting
1239 -- (potential "assigned but never read" case), but not if we
1240 -- have pragma Unreferenced, which cancels this error.
1242 and then (not Referenced_As_LHS_Check_Spec (E1)
1243 or else not Has_Unreferenced (E1))
1245 -- Check that warnings on unreferenced entities are enabled
1248 ((Check_Unreferenced and then not Is_Formal (E1))
1250 -- Case of warning on unreferenced formal
1253 (Check_Unreferenced_Formals and then Is_Formal (E1))
1255 -- Case of warning on unread variables modified by an
1256 -- assignment, or an out parameter if it is the only one.
1259 (Warn_On_Modified_Unread
1260 and then Referenced_As_LHS_Check_Spec (E1))
1262 -- Case of warning on any unread out parameter (note
1263 -- such indications are only set if the appropriate
1264 -- warning options were set, so no need to recheck here.
1267 Referenced_As_Out_Parameter_Check_Spec (E1))
1269 -- Labels, and enumeration literals, and exceptions. The
1270 -- warnings are also placed on local packages that cannot be
1271 -- referenced from elsewhere, including those declared within a
1274 and then (Is_Object (E1)
1278 Ekind (E1) = E_Label
1280 Ekind (E1) = E_Exception
1282 Ekind (E1) = E_Named_Integer
1284 Ekind (E1) = E_Named_Real
1286 Is_Overloadable (E1)
1288 -- Package case, if the main unit is a package
1289 -- spec or generic package spec, then there may
1290 -- be a corresponding body that references this
1291 -- package in some other file. Otherwise we can
1292 -- be sure that there is no other reference.
1295 (Ekind (E1) = E_Package
1297 Ekind (Cunit_Entity (Current_Sem_Unit)) /=
1300 Ekind (Cunit_Entity (Current_Sem_Unit)) /=
1303 -- Exclude instantiations, since there is no reason why every
1304 -- entity in an instantiation should be referenced.
1306 and then Instantiation_Location (Sloc (E1)) = No_Location
1308 -- Exclude formal parameters from bodies if the corresponding
1309 -- spec entity has been referenced in the case where there is
1312 and then not (Is_Formal (E1)
1314 Ekind (Scope (E1)) = E_Subprogram_Body
1316 Present (Spec_Entity (E1))
1318 Referenced (Spec_Entity (E1)))
1320 -- Consider private type referenced if full view is referenced
1321 -- If there is not full view, this is a generic type on which
1322 -- warnings are also useful.
1325 not (Is_Private_Type (E1)
1327 Present (Full_View (E1))
1328 and then Referenced (Full_View (E1)))
1330 -- Don't worry about full view, only about private type
1332 and then not Has_Private_Declaration (E1)
1334 -- Eliminate dispatching operations from consideration, we
1335 -- cannot tell if these are referenced or not in any easy
1336 -- manner (note this also catches Adjust/Finalize/Initialize)
1338 and then not Is_Dispatching_Operation (E1)
1340 -- Check entity that can be publicly referenced (we do not give
1341 -- messages for such entities, since there could be other
1342 -- units, not involved in this compilation, that contain
1343 -- relevant references.
1345 and then not Publicly_Referenceable (E1)
1347 -- Class wide types are marked as source entities, but they are
1348 -- not really source entities, and are always created, so we do
1349 -- not care if they are not referenced.
1351 and then Ekind (E1) /= E_Class_Wide_Type
1353 -- Objects other than parameters of task types are allowed to
1354 -- be non-referenced, since they start up tasks!
1356 and then ((Ekind (E1) /= E_Variable
1357 and then Ekind (E1) /= E_Constant
1358 and then Ekind (E1) /= E_Component)
1359 or else not Is_Task_Type (E1T))
1361 -- For subunits, only place warnings on the main unit itself,
1362 -- since parent units are not completely compiled
1364 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1366 Get_Source_Unit (E1) = Main_Unit)
1368 -- No warning on a return object, because these are often
1369 -- created with a single expression and an implicit return.
1370 -- If the object is a variable there will be a warning
1371 -- indicating that it could be declared constant.
1374 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1376 -- Suppress warnings in internal units if not in -gnatg mode
1377 -- (these would be junk warnings for an applications program,
1378 -- since they refer to problems in internal units)
1382 Is_Internal_File_Name
1383 (Unit_File_Name (Get_Source_Unit (E1)))
1385 -- We do not immediately flag the error. This is because we
1386 -- have not expanded generic bodies yet, and they may have
1387 -- the missing reference. So instead we park the entity on a
1388 -- list, for later processing. However for the case of an
1389 -- accept statement we want to output messages now, since
1390 -- we know we already have all information at hand, and we
1391 -- also want to have separate warnings for each accept
1392 -- statement for the same entry.
1394 if Present (Anod) then
1395 pragma Assert (Is_Formal (E1));
1397 -- The unreferenced entity is E1, but post the warning
1398 -- on the body entity for this accept statement.
1400 if not Warnings_Off_E1 then
1401 Warn_On_Unreferenced_Entity
1402 (E1, Body_Formal (E1, Accept_Statement => Anod));
1405 elsif not Warnings_Off_E1 then
1406 Unreferenced_Entities.Append (E1);
1410 -- Generic units are referenced in the generic body, but if they
1411 -- are not public and never instantiated we want to force a
1412 -- warning on them. We treat them as redundant constructs to
1415 elsif Is_Generic_Subprogram (E1)
1416 and then not Is_Instantiated (E1)
1417 and then not Publicly_Referenceable (E1)
1418 and then Instantiation_Depth (Sloc (E1)) = 0
1419 and then Warn_On_Redundant_Constructs
1421 if not Warnings_Off_E1 then
1422 Unreferenced_Entities.Append (E1);
1424 -- Force warning on entity
1426 Set_Referenced (E1, False);
1431 -- Recurse into nested package or block. Do not recurse into a
1432 -- formal package, because the corresponding body is not analyzed.
1435 if ((Ekind (E1) = E_Package or else Ekind (E1) = E_Generic_Package)
1436 and then Nkind (Parent (E1)) = N_Package_Specification
1438 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1439 /= N_Formal_Package_Declaration)
1441 or else Ekind (E1) = E_Block
1443 Check_References (E1);
1448 end Check_References;
1450 ---------------------------
1451 -- Check_Unset_Reference --
1452 ---------------------------
1454 procedure Check_Unset_Reference (N : Node_Id) is
1455 Typ : constant Entity_Id := Etype (N);
1457 function Is_OK_Fully_Initialized return Boolean;
1458 -- This function returns true if the given node N is fully initialized
1459 -- so that the reference is safe as far as this routine is concerned.
1460 -- Safe generally means that the type of N is a fully initialized type.
1461 -- The one special case is that for access types, which are always fully
1462 -- initialized, we don't consider a dereference OK since it will surely
1463 -- be dereferencing a null value, which won't do.
1465 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1466 -- Used to test indexed or selected component or slice to see if the
1467 -- evaluation of the prefix depends on a dereference, and if so, returns
1468 -- True, in which case we always check the prefix, even if we know that
1469 -- the referenced component is initialized. Pref is the prefix to test.
1471 -----------------------------
1472 -- Is_OK_Fully_Initialized --
1473 -----------------------------
1475 function Is_OK_Fully_Initialized return Boolean is
1477 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1480 return Is_Fully_Initialized_Type (Typ);
1482 end Is_OK_Fully_Initialized;
1484 ----------------------------
1485 -- Prefix_Has_Dereference --
1486 ----------------------------
1488 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1490 -- If prefix is of an access type, certainly need a dereference
1492 if Is_Access_Type (Etype (Pref)) then
1495 -- If prefix is explicit dereference, that's a dereference for sure
1497 elsif Nkind (Pref) = N_Explicit_Dereference then
1500 -- If prefix is itself a component reference or slice check prefix
1502 elsif Nkind (Pref) = N_Slice
1503 or else Nkind (Pref) = N_Indexed_Component
1504 or else Nkind (Pref) = N_Selected_Component
1506 return Prefix_Has_Dereference (Prefix (Pref));
1508 -- All other cases do not involve a dereference
1513 end Prefix_Has_Dereference;
1515 -- Start of processing for Check_Unset_Reference
1518 -- Nothing to do if warnings suppressed
1520 if Warning_Mode = Suppress then
1524 -- Ignore reference unless it comes from source. Almost always if we
1525 -- have a reference from generated code, it is bogus (e.g. calls to init
1526 -- procs to set default discriminant values).
1528 if not Comes_From_Source (N) then
1532 -- Otherwise see what kind of node we have. If the entity already
1533 -- has an unset reference, it is not necessarily the earliest in
1534 -- the text, because resolution of the prefix of selected components
1535 -- is completed before the resolution of the selected component itself.
1536 -- as a result, given (R /= null and then R.X > 0), the occurrences
1537 -- of R are examined in right-to-left order. If there is already an
1538 -- unset reference, we check whether N is earlier before proceeding.
1542 -- For identifier or expanded name, examine the entity involved
1544 when N_Identifier | N_Expanded_Name =>
1546 E : constant Entity_Id := Entity (N);
1549 if (Ekind (E) = E_Variable
1551 Ekind (E) = E_Out_Parameter)
1552 and then Never_Set_In_Source_Check_Spec (E)
1553 and then not Has_Initial_Value (E)
1554 and then (No (Unset_Reference (E))
1556 Earlier_In_Extended_Unit
1557 (Sloc (N), Sloc (Unset_Reference (E))))
1558 and then not Has_Pragma_Unmodified_Check_Spec (E)
1559 and then not Warnings_Off_Check_Spec (E)
1561 -- We may have an unset reference. The first test is whether
1562 -- this is an access to a discriminant of a record or a
1563 -- component with default initialization. Both of these
1564 -- cases can be ignored, since the actual object that is
1565 -- referenced is definitely initialized. Note that this
1566 -- covers the case of reading discriminants of an out
1567 -- parameter, which is OK even in Ada 83.
1569 -- Note that we are only interested in a direct reference to
1570 -- a record component here. If the reference is via an
1571 -- access type, then the access object is being referenced,
1572 -- not the record, and still deserves an unset reference.
1574 if Nkind (Parent (N)) = N_Selected_Component
1575 and not Is_Access_Type (Typ)
1578 ES : constant Entity_Id :=
1579 Entity (Selector_Name (Parent (N)));
1581 if Ekind (ES) = E_Discriminant
1583 (Present (Declaration_Node (ES))
1585 Present (Expression (Declaration_Node (ES))))
1592 -- Exclude fully initialized types
1594 if Is_OK_Fully_Initialized then
1598 -- Here we have a potential unset reference. But before we
1599 -- get worried about it, we have to make sure that the
1600 -- entity declaration is in the same procedure as the
1601 -- reference, since if they are in separate procedures, then
1602 -- we have no idea about sequential execution.
1604 -- The tests in the loop below catch all such cases, but do
1605 -- allow the reference to appear in a loop, block, or
1606 -- package spec that is nested within the declaring scope.
1607 -- As always, it is possible to construct cases where the
1608 -- warning is wrong, that is why it is a warning!
1612 SE : constant Entity_Id := Scope (E);
1615 SR := Current_Scope;
1617 if SR = Standard_Standard
1618 or else Is_Subprogram (SR)
1619 or else Is_Concurrent_Body (SR)
1620 or else Is_Concurrent_Type (SR)
1628 -- Case of reference has an access type. This is special
1629 -- case since access types are always set to null so
1630 -- cannot be truly uninitialized, but we still want to
1631 -- warn about cases of obvious null dereference.
1633 if Is_Access_Type (Typ) then
1634 Access_Type_Case : declare
1638 (N : Node_Id) return Traverse_Result;
1639 -- Process function for instantiation of Traverse
1640 -- below. Checks if N contains reference to other
1641 -- than a dereference.
1643 function Ref_In (Nod : Node_Id) return Boolean;
1644 -- Determines whether Nod contains a reference to
1645 -- the entity E that is not a dereference.
1652 (N : Node_Id) return Traverse_Result
1655 if Is_Entity_Name (N)
1656 and then Entity (N) = E
1657 and then not Is_Dereferenced (N)
1669 function Ref_In (Nod : Node_Id) return Boolean is
1670 function Traverse is new Traverse_Func (Process);
1672 return Traverse (Nod) = Abandon;
1675 -- Start of processing for Access_Type_Case
1678 -- Don't bother if we are inside an instance, since
1679 -- the compilation of the generic template is where
1680 -- the warning should be issued.
1686 -- Don't bother if this is not the main unit. If we
1687 -- try to give this warning for with'ed units, we
1688 -- get some false positives, since we do not record
1689 -- references in other units.
1691 if not In_Extended_Main_Source_Unit (E)
1693 not In_Extended_Main_Source_Unit (N)
1698 -- We are only interested in dereferences
1700 if not Is_Dereferenced (N) then
1704 -- One more check, don't bother with references
1705 -- that are inside conditional statements or while
1706 -- loops if the condition references the entity in
1707 -- question. This avoids most false positives.
1714 if (Nkind (P) = N_If_Statement
1716 Nkind (P) = N_Elsif_Part)
1717 and then Ref_In (Condition (P))
1721 elsif Nkind (P) = N_Loop_Statement
1722 and then Present (Iteration_Scheme (P))
1724 Ref_In (Condition (Iteration_Scheme (P)))
1729 end Access_Type_Case;
1732 -- Here we definitely have a case for giving a warning
1733 -- for a reference to an unset value. But we don't give
1734 -- the warning now. Instead we set the Unset_Reference
1735 -- field of the identifier involved. The reason for this
1736 -- is that if we find the variable is never ever assigned
1737 -- a value then that warning is more important and there
1738 -- is no point in giving the reference warning.
1740 -- If this is an identifier, set the field directly
1742 if Nkind (N) = N_Identifier then
1743 Set_Unset_Reference (E, N);
1745 -- Otherwise it is an expanded name, so set the field of
1746 -- the actual identifier for the reference.
1749 Set_Unset_Reference (E, Selector_Name (N));
1755 -- Indexed component or slice
1757 when N_Indexed_Component | N_Slice =>
1759 -- If prefix does not involve dereferencing an access type, then
1760 -- we know we are OK if the component type is fully initialized,
1761 -- since the component will have been set as part of the default
1764 if not Prefix_Has_Dereference (Prefix (N))
1765 and then Is_OK_Fully_Initialized
1769 -- Look at prefix in access type case, or if the component is not
1770 -- fully initialized.
1773 Check_Unset_Reference (Prefix (N));
1778 when N_Selected_Component =>
1780 Pref : constant Node_Id := Prefix (N);
1781 Ent : constant Entity_Id := Entity (Selector_Name (N));
1784 -- If prefix involves dereferencing an access type, always
1785 -- check the prefix, since the issue then is whether this
1786 -- access value is null.
1788 if Prefix_Has_Dereference (Pref) then
1791 -- Always go to prefix if no selector entity is set. Can this
1792 -- happen in the normal case? Not clear, but it definitely can
1793 -- happen in error cases.
1798 -- For a record component, check some cases where we have
1799 -- reasonable cause to consider that the component is known to
1800 -- be or probably is initialized. In this case, we don't care
1801 -- if the prefix itself was explicitly initialized.
1803 -- Discriminants are always considered initialized
1805 elsif Ekind (Ent) = E_Discriminant then
1808 -- An explicitly initialized component is certainly initialized
1810 elsif Nkind (Parent (Ent)) = N_Component_Declaration
1811 and then Present (Expression (Parent (Ent)))
1815 -- A fully initialized component is initialized
1817 elsif Is_OK_Fully_Initialized then
1821 -- If none of those cases apply, check the record type prefix
1823 Check_Unset_Reference (Pref);
1826 -- For type conversions or qualifications examine the expression
1828 when N_Type_Conversion | N_Qualified_Expression =>
1829 Check_Unset_Reference (Expression (N));
1831 -- For explicit dereference, always check prefix, which will generate
1832 -- an unset reference (since this is a case of dereferencing null).
1834 when N_Explicit_Dereference =>
1835 Check_Unset_Reference (Prefix (N));
1837 -- All other cases are not cases of an unset reference
1843 end Check_Unset_Reference;
1845 ------------------------
1846 -- Check_Unused_Withs --
1847 ------------------------
1849 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
1855 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
1856 -- This is needed for checking the special renaming case
1858 procedure Check_One_Unit (Unit : Unit_Number_Type);
1859 -- Subsidiary procedure, performs checks for specified unit
1861 --------------------
1862 -- Check_One_Unit --
1863 --------------------
1865 procedure Check_One_Unit (Unit : Unit_Number_Type) is
1866 Is_Visible_Renaming : Boolean := False;
1869 procedure Check_Inner_Package (Pack : Entity_Id);
1870 -- Pack is a package local to a unit in a with_clause. Both the
1871 -- unit and Pack are referenced. If none of the entities in Pack
1872 -- are referenced, then the only occurrence of Pack is in a use
1873 -- clause or a pragma, and a warning is worthwhile as well.
1875 function Check_System_Aux return Boolean;
1876 -- Before giving a warning on a with_clause for System, check
1877 -- whether a system extension is present.
1879 function Find_Package_Renaming
1881 L : Entity_Id) return Entity_Id;
1882 -- The only reference to a context unit may be in a renaming
1883 -- declaration. If this renaming declares a visible entity, do
1884 -- not warn that the context clause could be moved to the body,
1885 -- because the renaming may be intended to re-export the unit.
1887 -------------------------
1888 -- Check_Inner_Package --
1889 -------------------------
1891 procedure Check_Inner_Package (Pack : Entity_Id) is
1893 Un : constant Node_Id := Sinfo.Unit (Cnode);
1895 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
1896 -- If N is a use_clause for Pack, emit warning
1898 procedure Check_Use_Clauses is new
1899 Traverse_Proc (Check_Use_Clause);
1901 ----------------------
1902 -- Check_Use_Clause --
1903 ----------------------
1905 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
1909 if Nkind (N) = N_Use_Package_Clause then
1910 Nam := First (Names (N));
1911 while Present (Nam) loop
1912 if Entity (Nam) = Pack then
1913 Error_Msg_Qual_Level := 1;
1915 ("?no entities of package& are referenced!",
1917 Error_Msg_Qual_Level := 0;
1925 end Check_Use_Clause;
1927 -- Start of processing for Check_Inner_Package
1930 E := First_Entity (Pack);
1931 while Present (E) loop
1932 if Referenced_Check_Spec (E) then
1939 -- No entities of the package are referenced. Check whether the
1940 -- reference to the package itself is a use clause, and if so
1941 -- place a warning on it.
1943 Check_Use_Clauses (Un);
1944 end Check_Inner_Package;
1946 ----------------------
1947 -- Check_System_Aux --
1948 ----------------------
1950 function Check_System_Aux return Boolean is
1954 if Chars (Lunit) = Name_System
1955 and then Scope (Lunit) = Standard_Standard
1956 and then Present_System_Aux
1958 Ent := First_Entity (System_Aux_Id);
1959 while Present (Ent) loop
1960 if Referenced_Check_Spec (Ent) then
1969 end Check_System_Aux;
1971 ---------------------------
1972 -- Find_Package_Renaming --
1973 ---------------------------
1975 function Find_Package_Renaming
1977 L : Entity_Id) return Entity_Id
1983 Is_Visible_Renaming := False;
1985 E1 := First_Entity (P);
1986 while Present (E1) loop
1987 if Ekind (E1) = E_Package
1988 and then Renamed_Object (E1) = L
1990 Is_Visible_Renaming := not Is_Hidden (E1);
1993 elsif Ekind (E1) = E_Package
1994 and then No (Renamed_Object (E1))
1995 and then not Is_Generic_Instance (E1)
1997 R := Find_Package_Renaming (E1, L);
2000 Is_Visible_Renaming := not Is_Hidden (R);
2009 end Find_Package_Renaming;
2011 -- Start of processing for Check_One_Unit
2014 Cnode := Cunit (Unit);
2016 -- Only do check in units that are part of the extended main unit.
2017 -- This is actually a necessary restriction, because in the case of
2018 -- subprogram acting as its own specification, there can be with's in
2019 -- subunits that we will not see.
2021 if not In_Extended_Main_Source_Unit (Cnode) then
2024 -- In configurable run time mode, we remove the bodies of non-inlined
2025 -- subprograms, which may lead to spurious warnings, which are
2026 -- clearly undesirable.
2028 elsif Configurable_Run_Time_Mode
2029 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2034 -- Loop through context items in this unit
2036 Item := First (Context_Items (Cnode));
2037 while Present (Item) loop
2038 if Nkind (Item) = N_With_Clause
2039 and then not Implicit_With (Item)
2040 and then In_Extended_Main_Source_Unit (Item)
2042 Lunit := Entity (Name (Item));
2044 -- Check if this unit is referenced (skip the check if this
2045 -- is explicitly marked by a pragma Unreferenced).
2047 if not Referenced (Lunit)
2048 and then not Has_Unreferenced (Lunit)
2050 -- Suppress warnings in internal units if not in -gnatg mode
2051 -- (these would be junk warnings for an application program,
2052 -- since they refer to problems in internal units).
2055 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2057 -- Here we definitely have a non-referenced unit. If it
2058 -- is the special call for a spec unit, then just set the
2059 -- flag to be read later.
2061 if Unit = Spec_Unit then
2062 Set_Unreferenced_In_Spec (Item);
2064 -- Otherwise simple unreferenced message
2068 ("?unit& is not referenced!", Name (Item));
2072 -- If main unit is a renaming of this unit, then we consider
2073 -- the with to be OK (obviously it is needed in this case!)
2074 -- This may be transitive: the unit in the with_clause may
2075 -- itself be a renaming, in which case both it and the main
2076 -- unit rename the same ultimate package.
2078 elsif Present (Renamed_Entity (Munite))
2080 (Renamed_Entity (Munite) = Lunit
2081 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2085 -- If this unit is referenced, and it is a package, we do
2086 -- another test, to see if any of the entities in the package
2087 -- are referenced. If none of the entities are referenced, we
2088 -- still post a warning. This occurs if the only use of the
2089 -- package is in a use clause, or in a package renaming
2090 -- declaration. This check is skipped for packages that are
2091 -- renamed in a spec, since the entities in such a package are
2092 -- visible to clients via the renaming.
2094 elsif Ekind (Lunit) = E_Package
2095 and then not Renamed_In_Spec (Lunit)
2097 -- If Is_Instantiated is set, it means that the package is
2098 -- implicitly instantiated (this is the case of parent
2099 -- instance or an actual for a generic package formal), and
2100 -- this counts as a reference.
2102 if Is_Instantiated (Lunit) then
2105 -- If no entities in package, and there is a pragma
2106 -- Elaborate_Body present, then assume that this with is
2107 -- done for purposes of this elaboration.
2109 elsif No (First_Entity (Lunit))
2110 and then Has_Pragma_Elaborate_Body (Lunit)
2114 -- Otherwise see if any entities have been referenced
2117 if Limited_Present (Item) then
2118 Ent := First_Entity (Limited_View (Lunit));
2120 Ent := First_Entity (Lunit);
2124 -- No more entities, and we did not find one that was
2125 -- referenced. Means we have a definite case of a with
2126 -- none of whose entities was referenced.
2130 -- If in spec, just set the flag
2132 if Unit = Spec_Unit then
2133 Set_No_Entities_Ref_In_Spec (Item);
2135 elsif Check_System_Aux then
2138 -- Else give the warning
2142 Has_Unreferenced (Entity (Name (Item)))
2145 ("?no entities of & are referenced!",
2149 -- Look for renamings of this package, and flag
2150 -- them as well. If the original package has
2151 -- warnings off, we suppress the warning on the
2152 -- renaming as well.
2154 Pack := Find_Package_Renaming (Munite, Lunit);
2157 and then not Has_Warnings_Off (Lunit)
2158 and then not Has_Unreferenced (Pack)
2161 ("?no entities of & are referenced!",
2162 Unit_Declaration_Node (Pack),
2169 -- Case of entity being referenced. The reference may
2170 -- come from a limited_with_clause, in which case the
2171 -- limited view of the entity carries the flag.
2173 elsif Referenced_Check_Spec (Ent)
2174 or else Referenced_As_LHS_Check_Spec (Ent)
2175 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2177 (From_With_Type (Ent)
2178 and then Is_Incomplete_Type (Ent)
2179 and then Present (Non_Limited_View (Ent))
2180 and then Referenced (Non_Limited_View (Ent)))
2182 -- This means that the with is indeed fine, in that
2183 -- it is definitely needed somewhere, and we can
2184 -- quit worrying about this one...
2186 -- Except for one little detail: if either of the
2187 -- flags was set during spec processing, this is
2188 -- where we complain that the with could be moved
2189 -- from the spec. If the spec contains a visible
2190 -- renaming of the package, inhibit warning to move
2191 -- with_clause to body.
2193 if Ekind (Munite) = E_Package_Body then
2195 Find_Package_Renaming
2196 (Spec_Entity (Munite), Lunit);
2199 if Unreferenced_In_Spec (Item) then
2201 ("?unit& is not referenced in spec!",
2204 elsif No_Entities_Ref_In_Spec (Item) then
2206 ("?no entities of & are referenced in spec!",
2210 if Ekind (Ent) = E_Package then
2211 Check_Inner_Package (Ent);
2217 if not Is_Visible_Renaming then
2219 ("\?with clause might be moved to body!",
2225 -- Move to next entity to continue search
2233 -- For a generic package, the only interesting kind of
2234 -- reference is an instantiation, since entities cannot be
2235 -- referenced directly.
2237 elsif Is_Generic_Unit (Lunit) then
2239 -- Unit was never instantiated, set flag for case of spec
2240 -- call, or give warning for normal call.
2242 if not Is_Instantiated (Lunit) then
2243 if Unit = Spec_Unit then
2244 Set_Unreferenced_In_Spec (Item);
2247 ("?unit& is never instantiated!", Name (Item));
2250 -- If unit was indeed instantiated, make sure that flag is
2251 -- not set showing it was uninstantiated in the spec, and if
2252 -- so, give warning.
2254 elsif Unreferenced_In_Spec (Item) then
2256 ("?unit& is not instantiated in spec!", Name (Item));
2258 ("\?with clause can be moved to body!", Name (Item));
2267 -- Start of processing for Check_Unused_Withs
2270 if not Opt.Check_Withs
2271 or else Operating_Mode = Check_Syntax
2276 -- Flag any unused with clauses, but skip this step if we are compiling
2277 -- a subunit on its own, since we do not have enough information to
2278 -- determine whether with's are used. We will get the relevant warnings
2279 -- when we compile the parent. This is the normal style of GNAT
2280 -- compilation in any case.
2282 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2286 -- Process specified units
2288 if Spec_Unit = No_Unit then
2290 -- For main call, check all units
2292 for Unit in Main_Unit .. Last_Unit loop
2293 Check_One_Unit (Unit);
2297 -- For call for spec, check only the spec
2299 Check_One_Unit (Spec_Unit);
2301 end Check_Unused_Withs;
2303 ---------------------------------
2304 -- Generic_Package_Spec_Entity --
2305 ---------------------------------
2307 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2311 if Is_Package_Body_Entity (E) then
2317 if S = Standard_Standard then
2320 elsif Ekind (S) = E_Generic_Package then
2323 elsif Ekind (S) = E_Package then
2331 end Generic_Package_Spec_Entity;
2333 ----------------------
2334 -- Goto_Spec_Entity --
2335 ----------------------
2337 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2340 and then Present (Spec_Entity (E))
2342 return Spec_Entity (E);
2346 end Goto_Spec_Entity;
2348 --------------------------------------
2349 -- Has_Pragma_Unmodified_Check_Spec --
2350 --------------------------------------
2352 function Has_Pragma_Unmodified_Check_Spec
2353 (E : Entity_Id) return Boolean
2356 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2358 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2359 -- to mess with Unmodified flags on both body and spec entities.
2361 return Has_Unmodified (E)
2363 Has_Unmodified (Spec_Entity (E));
2366 return Has_Unmodified (E);
2368 end Has_Pragma_Unmodified_Check_Spec;
2370 ----------------------------------------
2371 -- Has_Pragma_Unreferenced_Check_Spec --
2372 ----------------------------------------
2374 function Has_Pragma_Unreferenced_Check_Spec
2375 (E : Entity_Id) return Boolean
2378 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2380 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2381 -- to mess with flags on both entities.
2383 return Has_Unreferenced (E)
2385 Has_Unreferenced (Spec_Entity (E));
2388 return Has_Unreferenced (E);
2390 end Has_Pragma_Unreferenced_Check_Spec;
2396 procedure Initialize is
2398 Warnings_Off_Pragmas.Init;
2399 Unreferenced_Entities.Init;
2400 In_Out_Warnings.Init;
2403 ------------------------------------
2404 -- Never_Set_In_Source_Check_Spec --
2405 ------------------------------------
2407 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2409 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2410 return Never_Set_In_Source (E)
2412 Never_Set_In_Source (Spec_Entity (E));
2414 return Never_Set_In_Source (E);
2416 end Never_Set_In_Source_Check_Spec;
2418 -------------------------------------
2419 -- Operand_Has_Warnings_Suppressed --
2420 -------------------------------------
2422 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2424 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2425 -- Function used to check one node to see if it is or was originally
2426 -- a reference to an entity for which Warnings are off. If so, Abandon
2427 -- is returned, otherwise OK_Orig is returned to continue the traversal
2428 -- of the original expression.
2430 function Traverse is new Traverse_Func (Check_For_Warnings);
2431 -- Function used to traverse tree looking for warnings
2433 ------------------------
2434 -- Check_For_Warnings --
2435 ------------------------
2437 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2438 R : constant Node_Id := Original_Node (N);
2441 if Nkind (R) in N_Has_Entity
2442 and then Present (Entity (R))
2443 and then Has_Warnings_Off (Entity (R))
2449 end Check_For_Warnings;
2451 -- Start of processing for Operand_Has_Warnings_Suppressed
2454 return Traverse (N) = Abandon;
2456 -- If any exception occurs, then something has gone wrong, and this is
2457 -- only a minor aesthetic issue anyway, so just say we did not find what
2458 -- we are looking for, rather than blow up.
2463 end Operand_Has_Warnings_Suppressed;
2465 -----------------------------------------
2466 -- Output_Non_Modified_In_Out_Warnings --
2467 -----------------------------------------
2469 procedure Output_Non_Modifed_In_Out_Warnings is
2471 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2472 -- Given a formal parameter entity E, determines if there is a reason to
2473 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2474 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2475 -- if we have seen the address of the subprogram being taken, or if the
2476 -- subprogram is used as a generic actual (in the latter cases the
2477 -- context may force use of IN OUT, even if the parameter is not
2478 -- modifies for this particular case.
2480 -----------------------
2481 -- No_Warn_On_In_Out --
2482 -----------------------
2484 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2485 S : constant Entity_Id := Scope (E);
2486 SE : constant Entity_Id := Spec_Entity (E);
2489 -- Do not warn if address is taken, since funny business may be going
2490 -- on in treating the parameter indirectly as IN OUT.
2492 if Address_Taken (S)
2493 or else (Present (SE) and then Address_Taken (Scope (SE)))
2497 -- Do not warn if used as a generic actual, since the generic may be
2498 -- what is forcing the use of an "unnecessary" IN OUT.
2500 elsif Used_As_Generic_Actual (S)
2501 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2505 -- Else test warnings off
2507 elsif Warnings_Off_Check_Spec (S) then
2510 -- All tests for suppressing warning failed
2515 end No_Warn_On_In_Out;
2517 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2520 -- Loop through entities for which a warning may be needed
2522 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2524 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2527 -- Suppress warning in specific cases (see details in comments for
2528 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2530 if Has_Pragma_Unmodified_Check_Spec (E1)
2531 or else No_Warn_On_In_Out (E1)
2535 -- Here we generate the warning
2538 -- If -gnatwc is set then output message that we could be IN
2540 if not Is_Trivial_Subprogram (Scope (E1)) then
2541 if Warn_On_Constant then
2543 ("?formal parameter & is not modified!", E1);
2545 ("\?mode could be IN instead of `IN OUT`!", E1);
2547 -- We do not generate warnings for IN OUT parameters
2548 -- unless we have at least -gnatwu. This is deliberately
2549 -- inconsistent with the treatment of variables, but
2550 -- otherwise we get too many unexpected warnings in
2553 elsif Check_Unreferenced then
2554 Error_Msg_N ("?formal parameter& is read but "
2555 & "never assigned!", E1);
2559 -- Kill any other warnings on this entity, since this is the
2560 -- one that should dominate any other unreferenced warning.
2562 Set_Warnings_Off (E1);
2566 end Output_Non_Modifed_In_Out_Warnings;
2568 ----------------------------------------
2569 -- Output_Obsolescent_Entity_Warnings --
2570 ----------------------------------------
2572 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2573 P : constant Node_Id := Parent (N);
2579 -- Do not output message if we are the scope of standard. This means
2580 -- we have a reference from a context clause from when it is originally
2581 -- processed, and that's too early to tell whether it is an obsolescent
2582 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2583 -- sure that we have a later call when the scope is available. This test
2584 -- also eliminates all messages for use clauses, which is fine (we do
2585 -- not want messages for use clauses, since they are always redundant
2586 -- with respect to the associated with clause).
2588 if S = Standard_Standard then
2592 -- Do not output message if we are in scope of an obsolescent package
2596 if Is_Obsolescent (S) then
2601 exit when S = Standard_Standard;
2604 -- Here we will output the message
2606 Error_Msg_Sloc := Sloc (E);
2608 -- Case of with clause
2610 if Nkind (P) = N_With_Clause then
2611 if Ekind (E) = E_Package then
2613 ("?with of obsolescent package& declared#", N, E);
2614 elsif Ekind (E) = E_Procedure then
2616 ("?with of obsolescent procedure& declared#", N, E);
2619 ("?with of obsolescent function& declared#", N, E);
2622 -- If we do not have a with clause, then ignore any reference to an
2623 -- obsolescent package name. We only want to give the one warning of
2624 -- withing the package, not one each time it is used to qualify.
2626 elsif Ekind (E) = E_Package then
2629 -- Procedure call statement
2631 elsif Nkind (P) = N_Procedure_Call_Statement then
2633 ("?call to obsolescent procedure& declared#", N, E);
2637 elsif Nkind (P) = N_Function_Call then
2639 ("?call to obsolescent function& declared#", N, E);
2641 -- Reference to obsolescent type
2643 elsif Is_Type (E) then
2645 ("?reference to obsolescent type& declared#", N, E);
2647 -- Reference to obsolescent component
2649 elsif Ekind (E) = E_Component
2650 or else Ekind (E) = E_Discriminant
2653 ("?reference to obsolescent component& declared#", N, E);
2655 -- Reference to obsolescent variable
2657 elsif Ekind (E) = E_Variable then
2659 ("?reference to obsolescent variable& declared#", N, E);
2661 -- Reference to obsolescent constant
2663 elsif Ekind (E) = E_Constant
2664 or else Ekind (E) in Named_Kind
2667 ("?reference to obsolescent constant& declared#", N, E);
2669 -- Reference to obsolescent enumeration literal
2671 elsif Ekind (E) = E_Enumeration_Literal then
2673 ("?reference to obsolescent enumeration literal& declared#", N, E);
2675 -- Generic message for any other case we missed
2679 ("?reference to obsolescent entity& declared#", N, E);
2682 -- Output additional warning if present
2684 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2685 if Obsolescent_Warnings.Table (J).Ent = E then
2686 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2687 Error_Msg_Strlen := Name_Len;
2688 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2689 Error_Msg_N ("\\?~", N);
2693 end Output_Obsolescent_Entity_Warnings;
2695 ----------------------------------
2696 -- Output_Unreferenced_Messages --
2697 ----------------------------------
2699 procedure Output_Unreferenced_Messages is
2701 for J in Unreferenced_Entities.First ..
2702 Unreferenced_Entities.Last
2704 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2706 end Output_Unreferenced_Messages;
2708 -----------------------------------------
2709 -- Output_Unused_Warnings_Off_Warnings --
2710 -----------------------------------------
2712 procedure Output_Unused_Warnings_Off_Warnings is
2714 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2716 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2717 N : Node_Id renames Wentry.N;
2718 E : Node_Id renames Wentry.E;
2721 -- Turn off Warnings_Off, or we won't get the warning!
2723 Set_Warnings_Off (E, False);
2725 -- Nothing to do if pragma was used to suppress a general warning
2727 if Warnings_Off_Used (E) then
2730 -- If pragma was used both in unmodified and unreferenced contexts
2731 -- then that's as good as the general case, no warning.
2733 elsif Warnings_Off_Used_Unmodified (E)
2735 Warnings_Off_Used_Unreferenced (E)
2739 -- Used only in context where Unmodified would have worked
2741 elsif Warnings_Off_Used_Unmodified (E) then
2743 ("?could use Unmodified instead of "
2744 & "Warnings Off for &", Pragma_Identifier (N), E);
2746 -- Used only in context where Unreferenced would have worked
2748 elsif Warnings_Off_Used_Unreferenced (E) then
2750 ("?could use Unreferenced instead of "
2751 & "Warnings Off for &", Pragma_Identifier (N), E);
2757 ("?pragma Warnings Off for & unused, "
2758 & "could be omitted", N, E);
2762 end Output_Unused_Warnings_Off_Warnings;
2764 ---------------------------
2765 -- Referenced_Check_Spec --
2766 ---------------------------
2768 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
2770 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2771 return Referenced (E) or else Referenced (Spec_Entity (E));
2773 return Referenced (E);
2775 end Referenced_Check_Spec;
2777 ----------------------------------
2778 -- Referenced_As_LHS_Check_Spec --
2779 ----------------------------------
2781 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
2783 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2784 return Referenced_As_LHS (E)
2785 or else Referenced_As_LHS (Spec_Entity (E));
2787 return Referenced_As_LHS (E);
2789 end Referenced_As_LHS_Check_Spec;
2791 --------------------------------------------
2792 -- Referenced_As_Out_Parameter_Check_Spec --
2793 --------------------------------------------
2795 function Referenced_As_Out_Parameter_Check_Spec
2796 (E : Entity_Id) return Boolean
2799 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2800 return Referenced_As_Out_Parameter (E)
2801 or else Referenced_As_Out_Parameter (Spec_Entity (E));
2803 return Referenced_As_Out_Parameter (E);
2805 end Referenced_As_Out_Parameter_Check_Spec;
2807 ----------------------------
2808 -- Set_Dot_Warning_Switch --
2809 ----------------------------
2811 function Set_Dot_Warning_Switch (C : Character) return Boolean is
2815 Warn_On_Assertion_Failure := True;
2818 Warn_On_Assertion_Failure := False;
2821 Warn_On_Unrepped_Components := True;
2824 Warn_On_Unrepped_Components := False;
2827 Address_Clause_Overlay_Warnings := True;
2828 Check_Unreferenced := True;
2829 Check_Unreferenced_Formals := True;
2830 Check_Withs := True;
2831 Constant_Condition_Warnings := True;
2832 Elab_Warnings := True;
2833 Implementation_Unit_Warnings := True;
2834 Ineffective_Inline_Warnings := True;
2835 Warn_On_Ada_2005_Compatibility := True;
2836 Warn_On_All_Unread_Out_Parameters := True;
2837 Warn_On_Assertion_Failure := True;
2838 Warn_On_Assumed_Low_Bound := True;
2839 Warn_On_Bad_Fixed_Value := True;
2840 Warn_On_Constant := True;
2841 Warn_On_Deleted_Code := True;
2842 Warn_On_Dereference := True;
2843 Warn_On_Export_Import := True;
2844 Warn_On_Hiding := True;
2845 Ineffective_Inline_Warnings := True;
2846 Warn_On_Modified_Unread := True;
2847 Warn_On_No_Value_Assigned := True;
2848 Warn_On_Non_Local_Exception := True;
2849 Warn_On_Object_Renames_Function := True;
2850 Warn_On_Obsolescent_Feature := True;
2851 Warn_On_Questionable_Missing_Parens := True;
2852 Warn_On_Redundant_Constructs := True;
2853 Warn_On_Unchecked_Conversion := True;
2854 Warn_On_Unrecognized_Pragma := True;
2855 Warn_On_Unrepped_Components := True;
2856 Warn_On_Warnings_Off := True;
2859 Warn_On_All_Unread_Out_Parameters := True;
2862 Warn_On_All_Unread_Out_Parameters := False;
2865 Warn_On_Parameter_Order := True;
2868 Warn_On_Parameter_Order := False;
2871 Warn_On_Object_Renames_Function := True;
2874 Warn_On_Object_Renames_Function := False;
2877 Warn_On_Warnings_Off := True;
2880 Warn_On_Warnings_Off := False;
2883 Warn_On_Non_Local_Exception := True;
2886 Warn_On_Non_Local_Exception := False;
2893 end Set_Dot_Warning_Switch;
2895 ------------------------
2896 -- Set_Warning_Switch --
2897 ------------------------
2899 function Set_Warning_Switch (C : Character) return Boolean is
2903 Check_Unreferenced := True;
2904 Check_Unreferenced_Formals := True;
2905 Check_Withs := True;
2906 Constant_Condition_Warnings := True;
2907 Implementation_Unit_Warnings := True;
2908 Ineffective_Inline_Warnings := True;
2909 Warn_On_Ada_2005_Compatibility := True;
2910 Warn_On_Assertion_Failure := True;
2911 Warn_On_Assumed_Low_Bound := True;
2912 Warn_On_Bad_Fixed_Value := True;
2913 Warn_On_Constant := True;
2914 Warn_On_Export_Import := True;
2915 Warn_On_Modified_Unread := True;
2916 Warn_On_No_Value_Assigned := True;
2917 Warn_On_Non_Local_Exception := True;
2918 Warn_On_Object_Renames_Function := True;
2919 Warn_On_Obsolescent_Feature := True;
2920 Warn_On_Parameter_Order := True;
2921 Warn_On_Questionable_Missing_Parens := True;
2922 Warn_On_Redundant_Constructs := True;
2923 Warn_On_Unchecked_Conversion := True;
2924 Warn_On_Unrecognized_Pragma := True;
2925 Warn_On_Unrepped_Components := True;
2928 Check_Unreferenced := False;
2929 Check_Unreferenced_Formals := False;
2930 Check_Withs := False;
2931 Constant_Condition_Warnings := False;
2932 Elab_Warnings := False;
2933 Implementation_Unit_Warnings := False;
2934 Ineffective_Inline_Warnings := False;
2935 Warn_On_Ada_2005_Compatibility := False;
2936 Warn_On_Assertion_Failure := False;
2937 Warn_On_Assumed_Low_Bound := False;
2938 Warn_On_Bad_Fixed_Value := False;
2939 Warn_On_Constant := False;
2940 Warn_On_Deleted_Code := False;
2941 Warn_On_Dereference := False;
2942 Warn_On_Export_Import := False;
2943 Warn_On_Hiding := False;
2944 Warn_On_Modified_Unread := False;
2945 Warn_On_No_Value_Assigned := False;
2946 Warn_On_Non_Local_Exception := False;
2947 Warn_On_Obsolescent_Feature := False;
2948 Warn_On_All_Unread_Out_Parameters := False;
2949 Warn_On_Parameter_Order := False;
2950 Warn_On_Questionable_Missing_Parens := False;
2951 Warn_On_Redundant_Constructs := False;
2952 Warn_On_Object_Renames_Function := False;
2953 Warn_On_Unchecked_Conversion := False;
2954 Warn_On_Unrecognized_Pragma := False;
2955 Warn_On_Unrepped_Components := False;
2956 Warn_On_Warnings_Off := False;
2959 Warn_On_Bad_Fixed_Value := True;
2962 Warn_On_Bad_Fixed_Value := False;
2965 Constant_Condition_Warnings := True;
2968 Constant_Condition_Warnings := False;
2971 Warn_On_Dereference := True;
2974 Warn_On_Dereference := False;
2977 Warning_Mode := Treat_As_Error;
2980 Check_Unreferenced_Formals := True;
2983 Check_Unreferenced_Formals := False;
2986 Warn_On_Unrecognized_Pragma := True;
2989 Warn_On_Unrecognized_Pragma := False;
2992 Warn_On_Hiding := True;
2995 Warn_On_Hiding := False;
2998 Implementation_Unit_Warnings := True;
3001 Implementation_Unit_Warnings := False;
3004 Warn_On_Obsolescent_Feature := True;
3007 Warn_On_Obsolescent_Feature := False;
3010 Warn_On_Constant := True;
3013 Warn_On_Constant := False;
3016 Elab_Warnings := True;
3019 Elab_Warnings := False;
3022 Warn_On_Modified_Unread := True;
3025 Warn_On_Modified_Unread := False;
3028 Warning_Mode := Normal;
3031 Address_Clause_Overlay_Warnings := True;
3034 Address_Clause_Overlay_Warnings := False;
3037 Ineffective_Inline_Warnings := True;
3040 Ineffective_Inline_Warnings := False;
3043 Warn_On_Questionable_Missing_Parens := True;
3046 Warn_On_Questionable_Missing_Parens := False;
3049 Warn_On_Redundant_Constructs := True;
3052 Warn_On_Redundant_Constructs := False;
3055 Warning_Mode := Suppress;
3058 Warn_On_Deleted_Code := True;
3061 Warn_On_Deleted_Code := False;
3064 Check_Unreferenced := True;
3065 Check_Withs := True;
3066 Check_Unreferenced_Formals := True;
3069 Check_Unreferenced := False;
3070 Check_Withs := False;
3071 Check_Unreferenced_Formals := False;
3074 Warn_On_No_Value_Assigned := True;
3077 Warn_On_No_Value_Assigned := False;
3080 Warn_On_Assumed_Low_Bound := True;
3083 Warn_On_Assumed_Low_Bound := False;
3086 Warn_On_Export_Import := True;
3089 Warn_On_Export_Import := False;
3092 Warn_On_Ada_2005_Compatibility := True;
3095 Warn_On_Ada_2005_Compatibility := False;
3098 Warn_On_Unchecked_Conversion := True;
3101 Warn_On_Unchecked_Conversion := False;
3108 end Set_Warning_Switch;
3110 -----------------------------
3111 -- Warn_On_Known_Condition --
3112 -----------------------------
3114 procedure Warn_On_Known_Condition (C : Node_Id) is
3117 procedure Track (N : Node_Id; Loc : Node_Id);
3118 -- Adds continuation warning(s) pointing to reason (assignment or test)
3119 -- for the operand of the conditional having a known value (or at least
3120 -- enough is known about the value to issue the warning). N is the node
3121 -- which is judged to have a known value. Loc is the warning location.
3127 procedure Track (N : Node_Id; Loc : Node_Id) is
3128 Nod : constant Node_Id := Original_Node (N);
3131 if Nkind (Nod) in N_Op_Compare then
3132 Track (Left_Opnd (Nod), Loc);
3133 Track (Right_Opnd (Nod), Loc);
3135 elsif Is_Entity_Name (Nod)
3136 and then Is_Object (Entity (Nod))
3139 CV : constant Node_Id := Current_Value (Entity (Nod));
3142 if Present (CV) then
3143 Error_Msg_Sloc := Sloc (CV);
3145 if Nkind (CV) not in N_Subexpr then
3146 Error_Msg_N ("\\?(see test #)", Loc);
3148 elsif Nkind (Parent (CV)) =
3149 N_Case_Statement_Alternative
3151 Error_Msg_N ("\\?(see case alternative #)", Loc);
3154 Error_Msg_N ("\\?(see assignment #)", Loc);
3161 -- Start of processing for Warn_On_Known_Condition
3164 -- Argument replacement in an inlined body can make conditions static.
3165 -- Do not emit warnings in this case.
3167 if In_Inlined_Body then
3171 if Constant_Condition_Warnings
3172 and then Nkind (C) = N_Identifier
3174 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3175 and then Comes_From_Source (Original_Node (C))
3176 and then not In_Instance
3178 -- See if this is in a statement or a declaration
3182 -- If tree is not attached, do not issue warning (this is very
3183 -- peculiar, and probably arises from some other error condition)
3188 -- If we are in a declaration, then no warning, since in practice
3189 -- conditionals in declarations are used for intended tests which
3190 -- may be known at compile time, e.g. things like
3192 -- x : constant Integer := 2 + (Word'Size = 32);
3194 -- And a warning is annoying in such cases
3196 elsif Nkind (P) in N_Declaration
3198 Nkind (P) in N_Later_Decl_Item
3202 -- Don't warn in assert or check pragma, since presumably tests in
3203 -- such a context are very definitely intended, and might well be
3204 -- known at compile time. Note that we have to test the original
3205 -- node, since assert pragmas get rewritten at analysis time.
3207 elsif Nkind (Original_Node (P)) = N_Pragma
3208 and then (Pragma_Name (Original_Node (P)) = Name_Assert
3210 Pragma_Name (Original_Node (P)) = Name_Check)
3215 exit when Is_Statement (P);
3219 -- Here we issue the warning unless some sub-operand has warnings
3220 -- set off, in which case we suppress the warning for the node. If
3221 -- the original expression is an inequality, it has been expanded
3222 -- into a negation, and the value of the original expression is the
3223 -- negation of the equality. If the expression is an entity that
3224 -- appears within a negation, it is clearer to flag the negation
3225 -- itself, and report on its constant value.
3227 if not Operand_Has_Warnings_Suppressed (C) then
3229 True_Branch : Boolean := Entity (C) = Standard_True;
3230 Cond : Node_Id := C;
3233 if Present (Parent (C))
3234 and then Nkind (Parent (C)) = N_Op_Not
3236 True_Branch := not True_Branch;
3241 if Is_Entity_Name (Original_Node (C))
3242 and then Nkind (Cond) /= N_Op_Not
3245 ("object & is always True?", Cond, Original_Node (C));
3246 Track (Original_Node (C), Cond);
3249 Error_Msg_N ("condition is always True?", Cond);
3254 Error_Msg_N ("condition is always False?", Cond);
3260 end Warn_On_Known_Condition;
3262 ---------------------------------------
3263 -- Warn_On_Modified_As_Out_Parameter --
3264 ---------------------------------------
3266 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3269 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3270 or else Warn_On_All_Unread_Out_Parameters;
3271 end Warn_On_Modified_As_Out_Parameter;
3273 ------------------------------
3274 -- Warn_On_Suspicious_Index --
3275 ------------------------------
3277 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3280 -- Set to lower bound for a suspicious type
3283 -- Entity for array reference
3288 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3289 -- Tests to see if Typ is a type for which we may have a suspicious
3290 -- index, namely an unconstrained array type, whose lower bound is
3291 -- either zero or one. If so, True is returned, and Low_Bound is set
3292 -- to this lower bound. If not, False is returned, and Low_Bound is
3293 -- undefined on return.
3295 -- For now, we limit this to standard string types, so any other
3296 -- unconstrained types return False. We may change our minds on this
3297 -- later on, but strings seem the most important case.
3299 procedure Test_Suspicious_Index;
3300 -- Test if index is of suspicious type and if so, generate warning
3302 ------------------------
3303 -- Is_Suspicious_Type --
3304 ------------------------
3306 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3310 if Is_Array_Type (Typ)
3311 and then not Is_Constrained (Typ)
3312 and then Number_Dimensions (Typ) = 1
3313 and then (Root_Type (Typ) = Standard_String
3315 Root_Type (Typ) = Standard_Wide_String
3317 Root_Type (Typ) = Standard_Wide_Wide_String)
3318 and then not Has_Warnings_Off (Typ)
3320 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3322 if Compile_Time_Known_Value (LB) then
3323 Low_Bound := Expr_Value (LB);
3324 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3329 end Is_Suspicious_Type;
3331 ---------------------------
3332 -- Test_Suspicious_Index --
3333 ---------------------------
3335 procedure Test_Suspicious_Index is
3337 function Length_Reference (N : Node_Id) return Boolean;
3338 -- Check if node N is of the form Name'Length
3341 -- Generate first warning line
3343 ----------------------
3344 -- Length_Reference --
3345 ----------------------
3347 function Length_Reference (N : Node_Id) return Boolean is
3348 R : constant Node_Id := Original_Node (N);
3351 Nkind (R) = N_Attribute_Reference
3352 and then Attribute_Name (R) = Name_Length
3353 and then Is_Entity_Name (Prefix (R))
3354 and then Entity (Prefix (R)) = Ent;
3355 end Length_Reference;
3363 Error_Msg_Uint_1 := Low_Bound;
3364 Error_Msg_FE ("?index for& may assume lower bound of^", X, Ent);
3367 -- Start of processing for Test_Suspicious_Index
3370 -- Nothing to do if subscript does not come from source (we don't
3371 -- want to give garbage warnings on compiler expanded code, e.g. the
3372 -- loops generated for slice assignments. Such junk warnings would
3373 -- be placed on source constructs with no subscript in sight!)
3375 if not Comes_From_Source (Original_Node (X)) then
3379 -- Case where subscript is a constant integer
3381 if Nkind (X) = N_Integer_Literal then
3384 -- Case where original form of subscript is an integer literal
3386 if Nkind (Original_Node (X)) = N_Integer_Literal then
3387 if Intval (X) = Low_Bound then
3389 ("\suggested replacement: `&''First`", X, Ent);
3391 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3393 ("\suggested replacement: `&''First + ^`", X, Ent);
3397 -- Case where original form of subscript is more complex
3400 -- Build string X'First - 1 + expression where the expression
3401 -- is the original subscript. If the expression starts with "1
3402 -- + ", then the "- 1 + 1" is elided.
3404 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3405 Error_Msg_Strlen := 13;
3408 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3409 Tref : constant Source_Buffer_Ptr :=
3410 Source_Text (Get_Source_File_Index (Sref));
3411 -- Tref (Sref) is used to scan the subscript
3414 -- Parentheses counter when scanning subscript
3417 -- Tref (Sref) points to start of subscript
3419 -- Elide - 1 if subscript starts with 1 +
3421 if Tref (Sref .. Sref + 2) = "1 +" then
3422 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3425 elsif Tref (Sref .. Sref + 1) = "1+" then
3426 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3430 -- Now we will copy the subscript to the string buffer
3434 -- Count parens, exit if terminating right paren. Note
3435 -- check to ignore paren appearing as character literal.
3437 if Tref (Sref + 1) = '''
3439 Tref (Sref - 1) = '''
3443 if Tref (Sref) = '(' then
3445 elsif Tref (Sref) = ')' then
3451 -- Done if terminating double dot (slice case)
3454 and then (Tref (Sref .. Sref + 1) = ".."
3456 Tref (Sref .. Sref + 2) = " ..");
3458 -- Quit if we have hit EOF character, something wrong
3460 if Tref (Sref) = EOF then
3464 -- String literals are too much of a pain to handle
3466 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3470 -- If we have a 'Range reference, then this is a case
3471 -- where we cannot easily give a replacement. Don't try!
3473 if Tref (Sref .. Sref + 4) = "range"
3474 and then Tref (Sref - 1) < 'A'
3475 and then Tref (Sref + 5) < 'A'
3480 -- Else store next character
3482 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3483 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3486 -- If we get more than 40 characters then the expression
3487 -- is too long to copy, or something has gone wrong. In
3488 -- either case, just skip the attempt at a suggested fix.
3490 if Error_Msg_Strlen > 40 then
3496 -- Replacement subscript is now in string buffer
3499 ("\suggested replacement: `&~`", Original_Node (X), Ent);
3502 -- Case where subscript is of the form X'Length
3504 elsif Length_Reference (X) then
3506 Error_Msg_Node_2 := Ent;
3508 ("\suggest replacement of `&''Length` by `&''Last`",
3511 -- Case where subscript is of the form X'Length - expression
3513 elsif Nkind (X) = N_Op_Subtract
3514 and then Length_Reference (Left_Opnd (X))
3517 Error_Msg_Node_2 := Ent;
3519 ("\suggest replacement of `&''Length` by `&''Last`",
3520 Left_Opnd (X), Ent);
3522 end Test_Suspicious_Index;
3524 -- Start of processing for Warn_On_Suspicious_Index
3527 -- Only process if warnings activated
3529 if Warn_On_Assumed_Low_Bound then
3531 -- Test if array is simple entity name
3533 if Is_Entity_Name (Name) then
3535 -- Test if array is parameter of unconstrained string type
3537 Ent := Entity (Name);
3541 and then Is_Suspicious_Type (Typ)
3542 and then not Low_Bound_Known (Ent)
3544 Test_Suspicious_Index;
3548 end Warn_On_Suspicious_Index;
3550 --------------------------------------
3551 -- Warn_On_Unassigned_Out_Parameter --
3552 --------------------------------------
3554 procedure Warn_On_Unassigned_Out_Parameter
3555 (Return_Node : Node_Id;
3556 Scope_Id : Entity_Id)
3562 -- Ignore if procedure or return statement does not come from source
3564 if not Comes_From_Source (Scope_Id)
3565 or else not Comes_From_Source (Return_Node)
3570 -- Loop through formals
3572 Form := First_Formal (Scope_Id);
3573 while Present (Form) loop
3575 -- We are only interested in OUT parameters that come from source
3576 -- and are never set in the source, and furthermore only in scalars
3577 -- since non-scalars generate too many false positives.
3579 if Ekind (Form) = E_Out_Parameter
3580 and then Never_Set_In_Source_Check_Spec (Form)
3581 and then Is_Scalar_Type (Etype (Form))
3582 and then not Present (Unset_Reference (Form))
3584 -- Before we issue the warning, an add ad hoc defence against the
3585 -- most common case of false positives with this warning which is
3586 -- the case where there is a Boolean OUT parameter that has been
3587 -- set, and whose meaning is "ignore the values of the other
3588 -- parameters". We can't of course reliably tell this case at
3589 -- compile time, but the following test kills a lot of false
3590 -- positives, without generating a significant number of false
3591 -- negatives (missed real warnings).
3593 Form2 := First_Formal (Scope_Id);
3594 while Present (Form2) loop
3595 if Ekind (Form2) = E_Out_Parameter
3596 and then Root_Type (Etype (Form2)) = Standard_Boolean
3597 and then not Never_Set_In_Source_Check_Spec (Form2)
3602 Next_Formal (Form2);
3605 -- Here all conditions are met, record possible unset reference
3607 Set_Unset_Reference (Form, Return_Node);
3612 end Warn_On_Unassigned_Out_Parameter;
3614 ---------------------------------
3615 -- Warn_On_Unreferenced_Entity --
3616 ---------------------------------
3618 procedure Warn_On_Unreferenced_Entity
3619 (Spec_E : Entity_Id;
3620 Body_E : Entity_Id := Empty)
3622 E : Entity_Id := Spec_E;
3625 if not Referenced_Check_Spec (E)
3626 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3627 and then not Warnings_Off_Check_Spec (E)
3632 -- Case of variable that is assigned but not read. We suppress
3633 -- the message if the variable is volatile, has an address
3634 -- clause, is aliased, or is a renaming, or is imported.
3636 if Referenced_As_LHS_Check_Spec (E)
3637 and then No (Address_Clause (E))
3638 and then not Is_Volatile (E)
3640 if Warn_On_Modified_Unread
3641 and then not Is_Imported (E)
3642 and then not Is_Return_Object (E)
3643 and then not Is_Aliased (E)
3644 and then No (Renamed_Object (E))
3646 if not Has_Pragma_Unmodified_Check_Spec (E) then
3648 ("?variable & is assigned but never read!", E);
3651 Set_Last_Assignment (E, Empty);
3654 -- Normal case of neither assigned nor read (exclude variables
3655 -- referenced as out parameters, since we already generated
3656 -- appropriate warnings at the call point in this case).
3658 elsif not Referenced_As_Out_Parameter (E) then
3660 -- We suppress the message for types for which a valid
3661 -- pragma Unreferenced_Objects has been given, otherwise
3662 -- we go ahead and give the message.
3664 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3666 -- Distinguish renamed case in message
3668 if Present (Renamed_Object (E))
3669 and then Comes_From_Source (Renamed_Object (E))
3672 ("?renamed variable & is not referenced!", E);
3675 ("?variable & is not referenced!", E);
3681 if Present (Renamed_Object (E))
3682 and then Comes_From_Source (Renamed_Object (E))
3685 ("?renamed constant & is not referenced!", E);
3687 Error_Msg_N ("?constant & is not referenced!", E);
3690 when E_In_Parameter |
3691 E_In_Out_Parameter =>
3693 -- Do not emit message for formals of a renaming, because
3694 -- they are never referenced explicitly.
3696 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E))))
3697 /= N_Subprogram_Renaming_Declaration
3699 -- Suppress this message for an IN OUT parameter of a
3700 -- non-scalar type, since it is normal to have only an
3701 -- assignment in such a case.
3703 if Ekind (E) = E_In_Parameter
3704 or else not Referenced_As_LHS_Check_Spec (E)
3705 or else Is_Scalar_Type (E)
3707 if Present (Body_E) then
3711 if not Is_Trivial_Subprogram (Scope (E)) then
3713 ("?formal parameter & is not referenced!",
3719 when E_Out_Parameter =>
3722 when E_Named_Integer |
3724 Error_Msg_N ("?named number & is not referenced!", E);
3726 when E_Enumeration_Literal =>
3727 Error_Msg_N ("?literal & is not referenced!", E);
3730 Error_Msg_N ("?function & is not referenced!", E);
3733 Error_Msg_N ("?procedure & is not referenced!", E);
3735 when E_Generic_Procedure =>
3737 ("?generic procedure & is never instantiated!", E);
3739 when E_Generic_Function =>
3741 ("?generic function & is never instantiated!", E);
3744 Error_Msg_N ("?type & is not referenced!", E);
3747 Error_Msg_N ("?& is not referenced!", E);
3750 -- Kill warnings on the entity on which the message has been posted
3752 Set_Warnings_Off (E);
3754 end Warn_On_Unreferenced_Entity;
3756 --------------------------------
3757 -- Warn_On_Useless_Assignment --
3758 --------------------------------
3760 procedure Warn_On_Useless_Assignment
3762 N : Node_Id := Empty)
3767 function Check_Ref (N : Node_Id) return Traverse_Result;
3768 -- Used to instantiate Traverse_Func. Returns Abandon if
3769 -- a reference to the entity in question is found.
3771 function Test_No_Refs is new Traverse_Func (Check_Ref);
3777 function Check_Ref (N : Node_Id) return Traverse_Result is
3779 -- Check reference to our identifier. We use name equality here
3780 -- because the exception handlers have not yet been analyzed. This
3781 -- is not quite right, but it really does not matter that we fail
3782 -- to output the warning in some obscure cases of name clashes.
3784 if Nkind (N) = N_Identifier
3785 and then Chars (N) = Chars (Ent)
3793 -- Start of processing for Warn_On_Useless_Assignment
3796 -- Check if this is a case we want to warn on, a scalar or access
3797 -- variable with the last assignment field set, with warnings enabled,
3798 -- and which is not imported or exported. We also check that it is OK
3799 -- to capture the value. We are not going to capture any value, but
3800 -- the warning messages depends on the same kind of conditions.
3802 if Is_Assignable (Ent)
3803 and then not Is_Return_Object (Ent)
3804 and then Present (Last_Assignment (Ent))
3805 and then not Is_Imported (Ent)
3806 and then not Is_Exported (Ent)
3807 and then Safe_To_Capture_Value (N, Ent)
3808 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
3810 -- Before we issue the message, check covering exception handlers.
3811 -- Search up tree for enclosing statement sequences and handlers.
3813 P := Parent (Last_Assignment (Ent));
3814 while Present (P) loop
3816 -- Something is really wrong if we don't find a handled statement
3817 -- sequence, so just suppress the warning.
3820 Set_Last_Assignment (Ent, Empty);
3823 -- When we hit a package/subprogram body, issue warning and exit
3825 elsif Nkind (P) = N_Subprogram_Body
3826 or else Nkind (P) = N_Package_Body
3828 -- Case of assigned value never referenced
3832 -- Don't give this for OUT and IN OUT formals, since
3833 -- clearly caller may reference the assigned value. Also
3834 -- never give such warnings for internal variables.
3836 if Ekind (Ent) = E_Variable
3837 and then not Is_Internal_Name (Chars (Ent))
3839 if Referenced_As_Out_Parameter (Ent) then
3841 ("?& modified by call, but value never referenced",
3842 Last_Assignment (Ent), Ent);
3845 ("?useless assignment to&, value never referenced!",
3846 Last_Assignment (Ent), Ent);
3850 -- Case of assigned value overwritten
3853 Error_Msg_Sloc := Sloc (N);
3855 if Referenced_As_Out_Parameter (Ent) then
3857 ("?& modified by call, but value overwritten #!",
3858 Last_Assignment (Ent), Ent);
3861 ("?useless assignment to&, value overwritten #!",
3862 Last_Assignment (Ent), Ent);
3866 -- Clear last assignment indication and we are done
3868 Set_Last_Assignment (Ent, Empty);
3871 -- Enclosing handled sequence of statements
3873 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
3875 -- Check exception handlers present
3877 if Present (Exception_Handlers (P)) then
3879 -- If we are not at the top level, we regard an inner
3880 -- exception handler as a decisive indicator that we should
3881 -- not generate the warning, since the variable in question
3882 -- may be accessed after an exception in the outer block.
3884 if Nkind (Parent (P)) /= N_Subprogram_Body
3885 and then Nkind (Parent (P)) /= N_Package_Body
3887 Set_Last_Assignment (Ent, Empty);
3890 -- Otherwise we are at the outer level. An exception
3891 -- handler is significant only if it references the
3892 -- variable in question.
3895 X := First (Exception_Handlers (P));
3896 while Present (X) loop
3897 if Test_No_Refs (X) = Abandon then
3898 Set_Last_Assignment (Ent, Empty);
3911 end Warn_On_Useless_Assignment;
3913 ---------------------------------
3914 -- Warn_On_Useless_Assignments --
3915 ---------------------------------
3917 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
3920 if Warn_On_Modified_Unread
3921 and then In_Extended_Main_Source_Unit (E)
3923 Ent := First_Entity (E);
3924 while Present (Ent) loop
3925 Warn_On_Useless_Assignment (Ent);
3929 end Warn_On_Useless_Assignments;
3931 -----------------------------
3932 -- Warnings_Off_Check_Spec --
3933 -----------------------------
3935 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
3937 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3939 -- Note: use of OR here instead of OR ELSE is deliberate, we want
3940 -- to mess with flags on both entities.
3942 return Has_Warnings_Off (E)
3944 Has_Warnings_Off (Spec_Entity (E));
3947 return Has_Warnings_Off (E);
3949 end Warnings_Off_Check_Spec;