1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2009, 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 might not be modified
240 -- in loop, indicating a possible infinite loop.
242 Var : Entity_Id := Empty;
243 -- Corresponding entity (entity of Ref)
245 Function_Call_Found : Boolean := False;
246 -- True if Find_Var found a function call in the condition
248 procedure Find_Var (N : Node_Id);
249 -- Inspect condition to see if it depends on a single entity reference.
250 -- If so, Ref is set to point to the reference node, and Var is set to
251 -- the referenced Entity.
253 function Has_Indirection (T : Entity_Id) return Boolean;
254 -- If the controlling variable is an access type, or is a record type
255 -- with access components, assume that it is changed indirectly and
256 -- suppress the warning. As a concession to low-level programming, in
257 -- particular within Declib, we also suppress warnings on a record
258 -- type that contains components of type Address or Short_Address.
260 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
261 -- Given an entity name, see if the name appears to have something to
262 -- do with I/O or network stuff, and if so, return True. Used to kill
263 -- some false positives on a heuristic basis that such functions will
264 -- likely have some strange side effect dependencies. A rather funny
265 -- kludge, but warning messages are in the heuristics business.
267 function Test_Ref (N : Node_Id) return Traverse_Result;
268 -- Test for reference to variable in question. Returns Abandon if
269 -- matching reference found.
271 function Find_Ref is new Traverse_Func (Test_Ref);
272 -- Function to traverse body of procedure. Returns Abandon if matching
279 procedure Find_Var (N : Node_Id) is
281 -- Condition is a direct variable reference
283 if Is_Entity_Name (N) then
287 -- Case of condition is a comparison with compile time known value
289 elsif Nkind (N) in N_Op_Compare then
290 if Compile_Time_Known_Value (Right_Opnd (N)) then
291 Find_Var (Left_Opnd (N));
293 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
294 Find_Var (Right_Opnd (N));
296 -- Ignore any other comparison
302 -- If condition is a negation, check its operand
304 elsif Nkind (N) = N_Op_Not then
305 Find_Var (Right_Opnd (N));
307 -- Case of condition is function call
309 elsif Nkind (N) = N_Function_Call then
311 Function_Call_Found := True;
313 -- Forget it if function name is not entity, who knows what
314 -- we might be calling?
316 if not Is_Entity_Name (Name (N)) then
319 -- Forget it if function name is suspicious. A strange test
320 -- but warning generation is in the heuristics business!
322 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
325 -- Forget it if warnings are suppressed on function entity
327 elsif Has_Warnings_Off (Entity (Name (N))) then
331 -- OK, see if we have one argument
334 PA : constant List_Id := Parameter_Associations (N);
337 -- One argument, so check the argument
340 and then List_Length (PA) = 1
342 if Nkind (First (PA)) = N_Parameter_Association then
343 Find_Var (Explicit_Actual_Parameter (First (PA)));
345 Find_Var (First (PA));
355 -- Any other kind of node is not something we warn for
362 ---------------------
363 -- Has_Indirection --
364 ---------------------
366 function Has_Indirection (T : Entity_Id) return Boolean is
371 if Is_Access_Type (T) then
374 elsif Is_Private_Type (T)
375 and then Present (Full_View (T))
376 and then Is_Access_Type (Full_View (T))
380 elsif Is_Record_Type (T) then
383 elsif Is_Private_Type (T)
384 and then Present (Full_View (T))
385 and then Is_Record_Type (Full_View (T))
387 Rec := Full_View (T);
392 Comp := First_Component (Rec);
393 while Present (Comp) loop
394 if Is_Access_Type (Etype (Comp))
395 or else Is_Descendent_Of_Address (Etype (Comp))
400 Next_Component (Comp);
406 ---------------------------------
407 -- Is_Suspicious_Function_Name --
408 ---------------------------------
410 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
413 function Substring_Present (S : String) return Boolean;
414 -- Returns True if name buffer has given string delimited by non-
415 -- alphabetic characters or by end of string. S is lower case.
417 -----------------------
418 -- Substring_Present --
419 -----------------------
421 function Substring_Present (S : String) return Boolean is
422 Len : constant Natural := S'Length;
425 for J in 1 .. Name_Len - (Len - 1) loop
426 if Name_Buffer (J .. J + (Len - 1)) = S
429 or else Name_Buffer (J - 1) not in 'a' .. 'z')
432 or else Name_Buffer (J + Len) not in 'a' .. 'z')
439 end Substring_Present;
441 -- Start of processing for Is_Suspicious_Function_Name
445 while Present (S) and then S /= Standard_Standard loop
446 Get_Name_String (Chars (S));
448 if Substring_Present ("io")
449 or else Substring_Present ("file")
450 or else Substring_Present ("network")
459 end Is_Suspicious_Function_Name;
465 function Test_Ref (N : Node_Id) return Traverse_Result is
467 -- Waste of time to look at iteration scheme
472 -- Direct reference to variable in question
474 elsif Is_Entity_Name (N)
475 and then Present (Entity (N))
476 and then Entity (N) = Var
478 -- If this is an lvalue, then definitely abandon, since
479 -- this could be a direct modification of the variable.
481 if May_Be_Lvalue (N) then
485 -- If we appear in the context of a procedure call, then also
486 -- abandon, since there may be issues of non-visible side
487 -- effects going on in the call.
496 exit when P = Loop_Statement;
498 -- Abandon if at procedure call, or something strange is
499 -- going on (perhaps a node with no parent that should
500 -- have one but does not?) As always, for a warning we
501 -- prefer to just abandon the warning than get into the
502 -- business of complaining about the tree structure here!
504 if No (P) or else Nkind (P) = N_Procedure_Call_Statement then
510 -- Reference to variable renaming variable in question
512 elsif Is_Entity_Name (N)
513 and then Present (Entity (N))
514 and then Ekind (Entity (N)) = E_Variable
515 and then Present (Renamed_Object (Entity (N)))
516 and then Is_Entity_Name (Renamed_Object (Entity (N)))
517 and then Entity (Renamed_Object (Entity (N))) = Var
518 and then May_Be_Lvalue (N)
522 -- Call to subprogram
524 elsif Nkind (N) = N_Procedure_Call_Statement
525 or else Nkind (N) = N_Function_Call
527 -- If subprogram is within the scope of the entity we are dealing
528 -- with as the loop variable, then it could modify this parameter,
529 -- so we abandon in this case. In the case of a subprogram that is
530 -- not an entity we also abandon. The check for no entity being
531 -- present is a defense against previous errors.
533 if not Is_Entity_Name (Name (N))
534 or else No (Entity (Name (N)))
535 or else Scope_Within (Entity (Name (N)), Scope (Var))
541 -- All OK, continue scan
546 -- Start of processing for Check_Infinite_Loop_Warning
549 -- We need a while iteration with no condition actions. Condition
550 -- actions just make things too complicated to get the warning right.
553 or else No (Condition (Iter))
554 or else Present (Condition_Actions (Iter))
555 or else Debug_Flag_Dot_W
560 -- Initial conditions met, see if condition is of right form
562 Find_Var (Condition (Iter));
564 -- Nothing to do if local variable from source not found. If it's a
565 -- renaming, it is probably renaming something too complicated to deal
569 or else Ekind (Var) /= E_Variable
570 or else Is_Library_Level_Entity (Var)
571 or else not Comes_From_Source (Var)
572 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
576 -- Nothing to do if there is some indirection involved (assume that the
577 -- designated variable might be modified in some way we don't see).
578 -- However, if no function call was found, then we don't care about
579 -- indirections, because the condition must be something like "while X
580 -- /= null loop", so we don't care if X.all is modified in the loop.
582 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
585 -- Same sort of thing for volatile variable, might be modified by
586 -- some other task or by the operating system in some way.
588 elsif Is_Volatile (Var) then
592 -- Filter out case of original statement sequence starting with delay.
593 -- We assume this is a multi-tasking program and that the condition
594 -- is affected by other threads (some kind of busy wait).
597 Fstm : constant Node_Id :=
598 Original_Node (First (Statements (Loop_Statement)));
600 if Nkind (Fstm) = N_Delay_Relative_Statement
601 or else Nkind (Fstm) = N_Delay_Until_Statement
607 -- We have a variable reference of the right form, now we scan the loop
608 -- body to see if it looks like it might not be modified
610 if Find_Ref (Loop_Statement) = OK then
612 ("?variable& is not modified in loop body!", Ref, Var);
614 ("\?possible infinite loop!", Ref);
616 end Check_Infinite_Loop_Warning;
618 ----------------------------
619 -- Check_Low_Bound_Tested --
620 ----------------------------
622 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
624 if Comes_From_Source (Expr) then
626 L : constant Node_Id := Left_Opnd (Expr);
627 R : constant Node_Id := Right_Opnd (Expr);
629 if Nkind (L) = N_Attribute_Reference
630 and then Attribute_Name (L) = Name_First
631 and then Is_Entity_Name (Prefix (L))
632 and then Is_Formal (Entity (Prefix (L)))
634 Set_Low_Bound_Tested (Entity (Prefix (L)));
637 if Nkind (R) = N_Attribute_Reference
638 and then Attribute_Name (R) = Name_First
639 and then Is_Entity_Name (Prefix (R))
640 and then Is_Formal (Entity (Prefix (R)))
642 Set_Low_Bound_Tested (Entity (Prefix (R)));
646 end Check_Low_Bound_Tested;
648 ----------------------
649 -- Check_References --
650 ----------------------
652 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
659 Accept_Statement : Node_Id) return Entity_Id;
660 -- For an entry formal entity from an entry declaration, find the
661 -- corresponding body formal from the given accept statement.
663 function Missing_Subunits return Boolean;
664 -- We suppress warnings when there are missing subunits, because this
665 -- may generate too many false positives: entities in a parent may only
666 -- be referenced in one of the subunits. We make an exception for
667 -- subunits that contain no other stubs.
669 procedure Output_Reference_Error (M : String);
670 -- Used to output an error message. Deals with posting the error on the
671 -- body formal in the accept case.
673 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
674 -- This is true if the entity in question is potentially referenceable
675 -- from another unit. This is true for entities in packages that are at
676 -- the library level.
678 function Warnings_Off_E1 return Boolean;
679 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
680 -- or for the base type of E1T.
688 Accept_Statement : Node_Id) return Entity_Id
690 Body_Param : Node_Id;
694 -- Loop to find matching parameter in accept statement
696 Body_Param := First (Parameter_Specifications (Accept_Statement));
697 while Present (Body_Param) loop
698 Body_E := Defining_Identifier (Body_Param);
700 if Chars (Body_E) = Chars (E) then
707 -- Should never fall through, should always find a match
712 ----------------------
713 -- Missing_Subunits --
714 ----------------------
716 function Missing_Subunits return Boolean is
720 if not Unloaded_Subunits then
722 -- Normal compilation, all subunits are present
726 elsif E /= Main_Unit_Entity then
728 -- No warnings on a stub that is not the main unit
732 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
733 D := First (Declarations (Unit_Declaration_Node (E)));
734 while Present (D) loop
736 -- No warnings if the proper body contains nested stubs
738 if Nkind (D) in N_Body_Stub then
748 -- Missing stubs elsewhere
752 end Missing_Subunits;
754 ----------------------------
755 -- Output_Reference_Error --
756 ----------------------------
758 procedure Output_Reference_Error (M : String) is
760 -- Never issue messages for internal names
762 if Is_Internal_Name (Chars (E1)) then
766 -- Don't output message for IN OUT formal unless we have the warning
767 -- flag specifically set. It is a bit odd to distinguish IN OUT
768 -- formals from other cases. This distinction is historical in
769 -- nature. Warnings for IN OUT formals were added fairly late.
771 if Ekind (E1) = E_In_Out_Parameter
772 and then not Check_Unreferenced_Formals
777 -- Other than accept case, post error on defining identifier
782 -- Accept case, find body formal to post the message
785 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
788 end Output_Reference_Error;
790 ----------------------------
791 -- Publicly_Referenceable --
792 ----------------------------
794 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
799 -- A formal parameter is never referenceable outside the body of its
800 -- subprogram or entry.
802 if Is_Formal (Ent) then
806 -- Examine parents to look for a library level package spec. But if
807 -- we find a body or block or other similar construct along the way,
808 -- we cannot be referenced.
815 -- If we get to top of tree, then publicly referenceable
820 -- If we reach a generic package declaration, then always
821 -- consider this referenceable, since any instantiation will
822 -- have access to the entities in the generic package. Note
823 -- that the package itself may not be instantiated, but then
824 -- we will get a warning for the package entity.
826 -- Note that generic formal parameters are themselves not
827 -- publicly referenceable in an instance, and warnings on them
830 when N_Generic_Package_Declaration =>
832 not Is_List_Member (Prev)
833 or else List_Containing (Prev)
834 /= Generic_Formal_Declarations (P);
836 -- Similarly, the generic formals of a generic subprogram are
839 when N_Generic_Subprogram_Declaration =>
840 if Is_List_Member (Prev)
841 and then List_Containing (Prev) =
842 Generic_Formal_Declarations (P)
849 -- If we reach a subprogram body, entity is not referenceable
850 -- unless it is the defining entity of the body. This will
851 -- happen, e.g. when a function is an attribute renaming that
852 -- is rewritten as a body.
854 when N_Subprogram_Body =>
855 if Ent /= Defining_Entity (P) then
861 -- If we reach any other body, definitely not referenceable
863 when N_Package_Body |
871 -- For all other cases, keep looking up tree
878 end Publicly_Referenceable;
880 ---------------------
881 -- Warnings_Off_E1 --
882 ---------------------
884 function Warnings_Off_E1 return Boolean is
886 return Has_Warnings_Off (E1T)
887 or else Has_Warnings_Off (Base_Type (E1T))
888 or else Warnings_Off_Check_Spec (E1);
891 -- Start of processing for Check_References
894 -- No messages if warnings are suppressed, or if we have detected any
895 -- real errors so far (this last check avoids junk messages resulting
896 -- from errors, e.g. a subunit that is not loaded).
898 if Warning_Mode = Suppress
899 or else Serious_Errors_Detected /= 0
904 -- We also skip the messages if any subunits were not loaded (see
905 -- comment in Sem_Ch10 to understand how this is set, and why it is
906 -- necessary to suppress the warnings in this case).
908 if Missing_Subunits then
912 -- Otherwise loop through entities, looking for suspicious stuff
914 E1 := First_Entity (E);
915 while Present (E1) loop
918 -- We are only interested in source entities. We also don't issue
919 -- warnings within instances, since the proper place for such
920 -- warnings is on the template when it is compiled.
922 if Comes_From_Source (E1)
923 and then Instantiation_Location (Sloc (E1)) = No_Location
925 -- We are interested in variables and out/in-out parameters, but
926 -- we exclude protected types, too complicated to worry about.
928 if Ekind (E1) = E_Variable
930 ((Ekind (E1) = E_Out_Parameter
931 or else Ekind (E1) = E_In_Out_Parameter)
932 and then not Is_Protected_Type (Current_Scope))
934 -- Case of an unassigned variable
936 -- First gather any Unset_Reference indication for E1. In the
937 -- case of a parameter, it is the Spec_Entity that is relevant.
939 if Ekind (E1) = E_Out_Parameter
940 and then Present (Spec_Entity (E1))
942 UR := Unset_Reference (Spec_Entity (E1));
944 UR := Unset_Reference (E1);
947 -- Special processing for access types
950 and then Is_Access_Type (E1T)
952 -- For access types, the only time we made a UR entry was
953 -- for a dereference, and so we post the appropriate warning
954 -- here (note that the dereference may not be explicit in
955 -- the source, for example in the case of a dispatching call
956 -- with an anonymous access controlling formal, or of an
957 -- assignment of a pointer involving discriminant check on
958 -- the designated object).
960 if not Warnings_Off_E1 then
961 Error_Msg_NE ("?& may be null!", UR, E1);
966 -- Case of variable that could be a constant. Note that we
967 -- never signal such messages for generic package entities,
968 -- since a given instance could have modifications outside
971 elsif Warn_On_Constant
972 and then (Ekind (E1) = E_Variable
973 and then Has_Initial_Value (E1))
974 and then Never_Set_In_Source_Check_Spec (E1)
975 and then not Address_Taken (E1)
976 and then not Generic_Package_Spec_Entity (E1)
978 -- A special case, if this variable is volatile and not
979 -- imported, it is not helpful to tell the programmer
980 -- to mark the variable as constant, since this would be
981 -- illegal by virtue of RM C.6(13).
983 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
984 and then not Is_Imported (E1)
987 ("?& is not modified, volatile has no effect!", E1);
989 -- Another special case, Exception_Occurrence, this catches
990 -- the case of exception choice (and a bit more too, but not
991 -- worth doing more investigation here).
993 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
996 -- Here we give the warning if referenced and no pragma
997 -- Unreferenced or Unmodified is present.
1002 if Ekind (E1) = E_Variable then
1003 if Referenced_Check_Spec (E1)
1004 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1005 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1007 if not Warnings_Off_E1 then
1008 Error_Msg_N -- CODEFIX
1009 ("?& is not modified, "
1010 & "could be declared constant!",
1017 -- Other cases of a variable or parameter never set in source
1019 elsif Never_Set_In_Source_Check_Spec (E1)
1021 -- No warning if warning for this case turned off
1023 and then Warn_On_No_Value_Assigned
1025 -- No warning if address taken somewhere
1027 and then not Address_Taken (E1)
1029 -- No warning if explicit initial value
1031 and then not Has_Initial_Value (E1)
1033 -- No warning for generic package spec entities, since we
1034 -- might set them in a child unit or something like that
1036 and then not Generic_Package_Spec_Entity (E1)
1038 -- No warning if fully initialized type, except that for
1039 -- this purpose we do not consider access types to qualify
1040 -- as fully initialized types (relying on an access type
1041 -- variable being null when it is never set is a bit odd!)
1043 -- Also we generate warning for an out parameter that is
1044 -- never referenced, since again it seems odd to rely on
1045 -- default initialization to set an out parameter value.
1047 and then (Is_Access_Type (E1T)
1048 or else Ekind (E1) = E_Out_Parameter
1049 or else not Is_Fully_Initialized_Type (E1T))
1051 -- Do not output complaint about never being assigned a
1052 -- value if a pragma Unmodified applies to the variable
1053 -- we are examining, or if it is a parameter, if there is
1054 -- a pragma Unreferenced for the corresponding spec, or
1055 -- if the type is marked as having unreferenced objects.
1056 -- The last is a little peculiar, but better too few than
1057 -- too many warnings in this situation.
1059 if Has_Pragma_Unreferenced_Objects (E1T)
1060 or else Has_Pragma_Unmodified_Check_Spec (E1)
1064 -- IN OUT parameter case where parameter is referenced. We
1065 -- separate this out, since this is the case where we delay
1066 -- output of the warning until more information is available
1067 -- (about use in an instantiation or address being taken).
1069 elsif Ekind (E1) = E_In_Out_Parameter
1070 and then Referenced_Check_Spec (E1)
1072 -- Suppress warning if private type, and the procedure
1073 -- has a separate declaration in a different unit. This
1074 -- is the case where the client of a package sees only
1075 -- the private type, and it may be quite reasonable
1076 -- for the logical view to be IN OUT, even if the
1077 -- implementation ends up using access types or some
1078 -- other method to achieve the local effect of a
1079 -- modification. On the other hand if the spec and body
1080 -- are in the same unit, we are in the package body and
1081 -- there we have less excuse for a junk IN OUT parameter.
1083 if Has_Private_Declaration (E1T)
1084 and then Present (Spec_Entity (E1))
1085 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1089 -- Suppress warning for any parameter of a dispatching
1090 -- operation, since it is quite reasonable to have an
1091 -- operation that is overridden, and for some subclasses
1092 -- needs the formal to be IN OUT and for others happens
1093 -- not to assign it.
1095 elsif Is_Dispatching_Operation
1096 (Scope (Goto_Spec_Entity (E1)))
1100 -- Suppress warning if composite type contains any access
1101 -- component, since the logical effect of modifying a
1102 -- parameter may be achieved by modifying a referenced
1105 elsif Is_Composite_Type (E1T)
1106 and then Has_Access_Values (E1T)
1110 -- Suppress warning on formals of an entry body. All
1111 -- references are attached to the formal in the entry
1112 -- declaration, which are marked Is_Entry_Formal.
1114 elsif Ekind (Scope (E1)) = E_Entry
1115 and then not Is_Entry_Formal (E1)
1119 -- OK, looks like warning for an IN OUT parameter that
1120 -- could be IN makes sense, but we delay the output of
1121 -- the warning, pending possibly finding out later on
1122 -- that the associated subprogram is used as a generic
1123 -- actual, or its address/access is taken. In these two
1124 -- cases, we suppress the warning because the context may
1125 -- force use of IN OUT, even if in this particular case
1126 -- the formal is not modified.
1129 In_Out_Warnings.Append (E1);
1132 -- Other cases of formals
1134 elsif Is_Formal (E1) then
1135 if not Is_Trivial_Subprogram (Scope (E1)) then
1136 if Referenced_Check_Spec (E1) then
1137 if not Has_Pragma_Unmodified_Check_Spec (E1)
1138 and then not Warnings_Off_E1
1140 Output_Reference_Error
1141 ("?formal parameter& is read but "
1142 & "never assigned!");
1145 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1146 and then not Warnings_Off_E1
1148 Output_Reference_Error
1149 ("?formal parameter& is not referenced!");
1156 if Referenced (E1) then
1157 if not Has_Unmodified (E1)
1158 and then not Warnings_Off_E1
1160 Output_Reference_Error
1161 ("?variable& is read but never assigned!");
1164 elsif not Has_Unreferenced (E1)
1165 and then not Warnings_Off_E1
1167 Output_Reference_Error -- CODEFIX
1168 ("?variable& is never read and never assigned!");
1171 -- Deal with special case where this variable is hidden
1172 -- by a loop variable.
1174 if Ekind (E1) = E_Variable
1175 and then Present (Hiding_Loop_Variable (E1))
1176 and then not Warnings_Off_E1
1179 ("?for loop implicitly declares loop variable!",
1180 Hiding_Loop_Variable (E1));
1182 Error_Msg_Sloc := Sloc (E1);
1184 ("\?declaration hides & declared#!",
1185 Hiding_Loop_Variable (E1));
1192 -- Check for unset reference
1194 if Warn_On_No_Value_Assigned and then Present (UR) then
1196 -- For other than access type, go back to original node to
1197 -- deal with case where original unset reference has been
1198 -- rewritten during expansion.
1200 -- In some cases, the original node may be a type conversion
1201 -- or qualification, and in this case we want the object
1204 UR := Original_Node (UR);
1205 while Nkind (UR) = N_Type_Conversion
1206 or else Nkind (UR) = N_Qualified_Expression
1208 UR := Expression (UR);
1211 -- Here we issue the warning, all checks completed
1213 -- If we have a return statement, this was a case of an OUT
1214 -- parameter not being set at the time of the return. (Note:
1215 -- it can't be N_Extended_Return_Statement, because those
1216 -- are only for functions, and functions do not allow OUT
1219 if not Is_Trivial_Subprogram (Scope (E1)) then
1220 if Nkind (UR) = N_Simple_Return_Statement
1221 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1223 if not Warnings_Off_E1 then
1225 ("?OUT parameter& not set before return", UR, E1);
1228 -- If the unset reference is a selected component
1229 -- prefix from source, mention the component as well.
1230 -- If the selected component comes from expansion, all
1231 -- we know is that the entity is not fully initialized
1232 -- at the point of the reference. Locate a random
1233 -- uninitialized component to get a better message.
1235 elsif Nkind (Parent (UR)) = N_Selected_Component then
1236 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1238 if not Comes_From_Source (Parent (UR)) then
1243 Comp := First_Entity (E1T);
1244 while Present (Comp) loop
1245 if Ekind (Comp) = E_Component
1246 and then Nkind (Parent (Comp)) =
1247 N_Component_Declaration
1248 and then No (Expression (Parent (Comp)))
1250 Error_Msg_Node_2 := Comp;
1259 -- Issue proper warning. This is a case of referencing
1260 -- a variable before it has been explicitly assigned.
1261 -- For access types, UR was only set for dereferences,
1262 -- so the issue is that the value may be null.
1264 if not Is_Trivial_Subprogram (Scope (E1)) then
1265 if not Warnings_Off_E1 then
1266 if Is_Access_Type (Etype (Parent (UR))) then
1267 Error_Msg_N ("?`&.&` may be null!", UR);
1270 ("?`&.&` may be referenced before "
1271 & "it has a value!", UR);
1276 -- All other cases of unset reference active
1278 elsif not Warnings_Off_E1 then
1280 ("?& may be referenced before it has a value!",
1289 -- Then check for unreferenced entities. Note that we are only
1290 -- interested in entities whose Referenced flag is not set.
1292 if not Referenced_Check_Spec (E1)
1294 -- If Referenced_As_LHS is set, then that's still interesting
1295 -- (potential "assigned but never read" case), but not if we
1296 -- have pragma Unreferenced, which cancels this warning.
1298 and then (not Referenced_As_LHS_Check_Spec (E1)
1299 or else not Has_Unreferenced (E1))
1301 -- Check that warnings on unreferenced entities are enabled
1304 ((Check_Unreferenced and then not Is_Formal (E1))
1306 -- Case of warning on unreferenced formal
1309 (Check_Unreferenced_Formals and then Is_Formal (E1))
1311 -- Case of warning on unread variables modified by an
1312 -- assignment, or an OUT parameter if it is the only one.
1315 (Warn_On_Modified_Unread
1316 and then Referenced_As_LHS_Check_Spec (E1))
1318 -- Case of warning on any unread OUT parameter (note
1319 -- such indications are only set if the appropriate
1320 -- warning options were set, so no need to recheck here.
1323 Referenced_As_Out_Parameter_Check_Spec (E1))
1325 -- Labels, and enumeration literals, and exceptions. The
1326 -- warnings are also placed on local packages that cannot be
1327 -- referenced from elsewhere, including those declared within a
1330 and then (Is_Object (E1)
1334 Ekind (E1) = E_Label
1336 Ekind (E1) = E_Exception
1338 Ekind (E1) = E_Named_Integer
1340 Ekind (E1) = E_Named_Real
1342 Is_Overloadable (E1)
1344 -- Package case, if the main unit is a package spec
1345 -- or generic package spec, then there may be a
1346 -- corresponding body that references this package
1347 -- in some other file. Otherwise we can be sure
1348 -- that there is no other reference.
1351 (Ekind (E1) = E_Package
1353 not Is_Package_Or_Generic_Package
1354 (Cunit_Entity (Current_Sem_Unit))))
1356 -- Exclude instantiations, since there is no reason why every
1357 -- entity in an instantiation should be referenced.
1359 and then Instantiation_Location (Sloc (E1)) = No_Location
1361 -- Exclude formal parameters from bodies if the corresponding
1362 -- spec entity has been referenced in the case where there is
1365 and then not (Is_Formal (E1)
1367 Ekind (Scope (E1)) = E_Subprogram_Body
1369 Present (Spec_Entity (E1))
1371 Referenced (Spec_Entity (E1)))
1373 -- Consider private type referenced if full view is referenced.
1374 -- If there is not full view, this is a generic type on which
1375 -- warnings are also useful.
1378 not (Is_Private_Type (E1)
1380 Present (Full_View (E1))
1381 and then Referenced (Full_View (E1)))
1383 -- Don't worry about full view, only about private type
1385 and then not Has_Private_Declaration (E1)
1387 -- Eliminate dispatching operations from consideration, we
1388 -- cannot tell if these are referenced or not in any easy
1389 -- manner (note this also catches Adjust/Finalize/Initialize).
1391 and then not Is_Dispatching_Operation (E1)
1393 -- Check entity that can be publicly referenced (we do not give
1394 -- messages for such entities, since there could be other
1395 -- units, not involved in this compilation, that contain
1396 -- relevant references.
1398 and then not Publicly_Referenceable (E1)
1400 -- Class wide types are marked as source entities, but they are
1401 -- not really source entities, and are always created, so we do
1402 -- not care if they are not referenced.
1404 and then Ekind (E1) /= E_Class_Wide_Type
1406 -- Objects other than parameters of task types are allowed to
1407 -- be non-referenced, since they start up tasks!
1409 and then ((Ekind (E1) /= E_Variable
1410 and then Ekind (E1) /= E_Constant
1411 and then Ekind (E1) /= E_Component)
1412 or else not Is_Task_Type (E1T))
1414 -- For subunits, only place warnings on the main unit itself,
1415 -- since parent units are not completely compiled.
1417 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1419 Get_Source_Unit (E1) = Main_Unit)
1421 -- No warning on a return object, because these are often
1422 -- created with a single expression and an implicit return.
1423 -- If the object is a variable there will be a warning
1424 -- indicating that it could be declared constant.
1427 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1429 -- Suppress warnings in internal units if not in -gnatg mode
1430 -- (these would be junk warnings for an applications program,
1431 -- since they refer to problems in internal units).
1435 Is_Internal_File_Name
1436 (Unit_File_Name (Get_Source_Unit (E1)))
1438 -- We do not immediately flag the error. This is because we
1439 -- have not expanded generic bodies yet, and they may have
1440 -- the missing reference. So instead we park the entity on a
1441 -- list, for later processing. However for the case of an
1442 -- accept statement we want to output messages now, since
1443 -- we know we already have all information at hand, and we
1444 -- also want to have separate warnings for each accept
1445 -- statement for the same entry.
1447 if Present (Anod) then
1448 pragma Assert (Is_Formal (E1));
1450 -- The unreferenced entity is E1, but post the warning
1451 -- on the body entity for this accept statement.
1453 if not Warnings_Off_E1 then
1454 Warn_On_Unreferenced_Entity
1455 (E1, Body_Formal (E1, Accept_Statement => Anod));
1458 elsif not Warnings_Off_E1 then
1459 Unreferenced_Entities.Append (E1);
1463 -- Generic units are referenced in the generic body, but if they
1464 -- are not public and never instantiated we want to force a
1465 -- warning on them. We treat them as redundant constructs to
1468 elsif Is_Generic_Subprogram (E1)
1469 and then not Is_Instantiated (E1)
1470 and then not Publicly_Referenceable (E1)
1471 and then Instantiation_Depth (Sloc (E1)) = 0
1472 and then Warn_On_Redundant_Constructs
1474 if not Warnings_Off_E1 then
1475 Unreferenced_Entities.Append (E1);
1477 -- Force warning on entity
1479 Set_Referenced (E1, False);
1484 -- Recurse into nested package or block. Do not recurse into a formal
1485 -- package, because the corresponding body is not analyzed.
1488 if (Is_Package_Or_Generic_Package (E1)
1489 and then Nkind (Parent (E1)) = N_Package_Specification
1491 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1492 /= N_Formal_Package_Declaration)
1494 or else Ekind (E1) = E_Block
1496 Check_References (E1);
1501 end Check_References;
1503 ---------------------------
1504 -- Check_Unset_Reference --
1505 ---------------------------
1507 procedure Check_Unset_Reference (N : Node_Id) is
1508 Typ : constant Entity_Id := Etype (N);
1510 function Is_OK_Fully_Initialized return Boolean;
1511 -- This function returns true if the given node N is fully initialized
1512 -- so that the reference is safe as far as this routine is concerned.
1513 -- Safe generally means that the type of N is a fully initialized type.
1514 -- The one special case is that for access types, which are always fully
1515 -- initialized, we don't consider a dereference OK since it will surely
1516 -- be dereferencing a null value, which won't do.
1518 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1519 -- Used to test indexed or selected component or slice to see if the
1520 -- evaluation of the prefix depends on a dereference, and if so, returns
1521 -- True, in which case we always check the prefix, even if we know that
1522 -- the referenced component is initialized. Pref is the prefix to test.
1524 -----------------------------
1525 -- Is_OK_Fully_Initialized --
1526 -----------------------------
1528 function Is_OK_Fully_Initialized return Boolean is
1530 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1533 return Is_Fully_Initialized_Type (Typ);
1535 end Is_OK_Fully_Initialized;
1537 ----------------------------
1538 -- Prefix_Has_Dereference --
1539 ----------------------------
1541 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1543 -- If prefix is of an access type, it certainly needs a dereference
1545 if Is_Access_Type (Etype (Pref)) then
1548 -- If prefix is explicit dereference, that's a dereference for sure
1550 elsif Nkind (Pref) = N_Explicit_Dereference then
1553 -- If prefix is itself a component reference or slice check prefix
1555 elsif Nkind (Pref) = N_Slice
1556 or else Nkind (Pref) = N_Indexed_Component
1557 or else Nkind (Pref) = N_Selected_Component
1559 return Prefix_Has_Dereference (Prefix (Pref));
1561 -- All other cases do not involve a dereference
1566 end Prefix_Has_Dereference;
1568 -- Start of processing for Check_Unset_Reference
1571 -- Nothing to do if warnings suppressed
1573 if Warning_Mode = Suppress then
1577 -- Ignore reference unless it comes from source. Almost always if we
1578 -- have a reference from generated code, it is bogus (e.g. calls to init
1579 -- procs to set default discriminant values).
1581 if not Comes_From_Source (N) then
1585 -- Otherwise see what kind of node we have. If the entity already has an
1586 -- unset reference, it is not necessarily the earliest in the text,
1587 -- because resolution of the prefix of selected components is completed
1588 -- before the resolution of the selected component itself. As a result,
1589 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1590 -- in right-to-left order. If there is already an unset reference, we
1591 -- check whether N is earlier before proceeding.
1595 -- For identifier or expanded name, examine the entity involved
1597 when N_Identifier | N_Expanded_Name =>
1599 E : constant Entity_Id := Entity (N);
1602 if (Ekind (E) = E_Variable
1604 Ekind (E) = E_Out_Parameter)
1605 and then Never_Set_In_Source_Check_Spec (E)
1606 and then not Has_Initial_Value (E)
1607 and then (No (Unset_Reference (E))
1609 Earlier_In_Extended_Unit
1610 (Sloc (N), Sloc (Unset_Reference (E))))
1611 and then not Has_Pragma_Unmodified_Check_Spec (E)
1612 and then not Warnings_Off_Check_Spec (E)
1614 -- We may have an unset reference. The first test is whether
1615 -- this is an access to a discriminant of a record or a
1616 -- component with default initialization. Both of these
1617 -- cases can be ignored, since the actual object that is
1618 -- referenced is definitely initialized. Note that this
1619 -- covers the case of reading discriminants of an OUT
1620 -- parameter, which is OK even in Ada 83.
1622 -- Note that we are only interested in a direct reference to
1623 -- a record component here. If the reference is through an
1624 -- access type, then the access object is being referenced,
1625 -- not the record, and still deserves an unset reference.
1627 if Nkind (Parent (N)) = N_Selected_Component
1628 and not Is_Access_Type (Typ)
1631 ES : constant Entity_Id :=
1632 Entity (Selector_Name (Parent (N)));
1634 if Ekind (ES) = E_Discriminant
1636 (Present (Declaration_Node (ES))
1638 Present (Expression (Declaration_Node (ES))))
1645 -- Exclude fully initialized types
1647 if Is_OK_Fully_Initialized then
1651 -- Here we have a potential unset reference. But before we
1652 -- get worried about it, we have to make sure that the
1653 -- entity declaration is in the same procedure as the
1654 -- reference, since if they are in separate procedures, then
1655 -- we have no idea about sequential execution.
1657 -- The tests in the loop below catch all such cases, but do
1658 -- allow the reference to appear in a loop, block, or
1659 -- package spec that is nested within the declaring scope.
1660 -- As always, it is possible to construct cases where the
1661 -- warning is wrong, that is why it is a warning!
1663 Potential_Unset_Reference : declare
1665 SE : constant Entity_Id := Scope (E);
1667 function Within_Postcondition return Boolean;
1668 -- Returns True iff N is within a Precondition
1670 --------------------------
1671 -- Within_Postcondition --
1672 --------------------------
1674 function Within_Postcondition return Boolean is
1679 while Present (Nod) loop
1680 if Nkind (Nod) = N_Pragma
1681 and then Pragma_Name (Nod) = Name_Postcondition
1686 Nod := Parent (Nod);
1690 end Within_Postcondition;
1692 -- Start of processing for Potential_Unset_Reference
1695 SR := Current_Scope;
1697 if SR = Standard_Standard
1698 or else Is_Subprogram (SR)
1699 or else Is_Concurrent_Body (SR)
1700 or else Is_Concurrent_Type (SR)
1708 -- Case of reference has an access type. This is a
1709 -- special case since access types are always set to null
1710 -- so cannot be truly uninitialized, but we still want to
1711 -- warn about cases of obvious null dereference.
1713 if Is_Access_Type (Typ) then
1714 Access_Type_Case : declare
1718 (N : Node_Id) return Traverse_Result;
1719 -- Process function for instantiation of Traverse
1720 -- below. Checks if N contains reference to E other
1721 -- than a dereference.
1723 function Ref_In (Nod : Node_Id) return Boolean;
1724 -- Determines whether Nod contains a reference to
1725 -- the entity E that is not a dereference.
1732 (N : Node_Id) return Traverse_Result
1735 if Is_Entity_Name (N)
1736 and then Entity (N) = E
1737 and then not Is_Dereferenced (N)
1749 function Ref_In (Nod : Node_Id) return Boolean is
1750 function Traverse is new Traverse_Func (Process);
1752 return Traverse (Nod) = Abandon;
1755 -- Start of processing for Access_Type_Case
1758 -- Don't bother if we are inside an instance, since
1759 -- the compilation of the generic template is where
1760 -- the warning should be issued.
1766 -- Don't bother if this is not the main unit. If we
1767 -- try to give this warning for with'ed units, we
1768 -- get some false positives, since we do not record
1769 -- references in other units.
1771 if not In_Extended_Main_Source_Unit (E)
1773 not In_Extended_Main_Source_Unit (N)
1778 -- We are only interested in dereferences
1780 if not Is_Dereferenced (N) then
1784 -- One more check, don't bother with references
1785 -- that are inside conditional statements or WHILE
1786 -- loops if the condition references the entity in
1787 -- question. This avoids most false positives.
1794 if (Nkind (P) = N_If_Statement
1796 Nkind (P) = N_Elsif_Part)
1797 and then Ref_In (Condition (P))
1801 elsif Nkind (P) = N_Loop_Statement
1802 and then Present (Iteration_Scheme (P))
1804 Ref_In (Condition (Iteration_Scheme (P)))
1809 end Access_Type_Case;
1812 -- One more check, don't bother if we are within a
1813 -- postcondition pragma, since the expression occurs
1814 -- in a place unrelated to the actual test.
1816 if not Within_Postcondition then
1818 -- Here we definitely have a case for giving a warning
1819 -- for a reference to an unset value. But we don't
1820 -- give the warning now. Instead set Unset_Reference
1821 -- in the identifier involved. The reason for this is
1822 -- that if we find the variable is never ever assigned
1823 -- a value then that warning is more important and
1824 -- there is no point in giving the reference warning.
1826 -- If this is an identifier, set the field directly
1828 if Nkind (N) = N_Identifier then
1829 Set_Unset_Reference (E, N);
1831 -- Otherwise it is an expanded name, so set the field
1832 -- of the actual identifier for the reference.
1835 Set_Unset_Reference (E, Selector_Name (N));
1838 end Potential_Unset_Reference;
1842 -- Indexed component or slice
1844 when N_Indexed_Component | N_Slice =>
1846 -- If prefix does not involve dereferencing an access type, then
1847 -- we know we are OK if the component type is fully initialized,
1848 -- since the component will have been set as part of the default
1851 if not Prefix_Has_Dereference (Prefix (N))
1852 and then Is_OK_Fully_Initialized
1856 -- Look at prefix in access type case, or if the component is not
1857 -- fully initialized.
1860 Check_Unset_Reference (Prefix (N));
1865 when N_Selected_Component =>
1867 Pref : constant Node_Id := Prefix (N);
1868 Ent : constant Entity_Id := Entity (Selector_Name (N));
1871 -- If prefix involves dereferencing an access type, always
1872 -- check the prefix, since the issue then is whether this
1873 -- access value is null.
1875 if Prefix_Has_Dereference (Pref) then
1878 -- Always go to prefix if no selector entity is set. Can this
1879 -- happen in the normal case? Not clear, but it definitely can
1880 -- happen in error cases.
1885 -- For a record component, check some cases where we have
1886 -- reasonable cause to consider that the component is known to
1887 -- be or probably is initialized. In this case, we don't care
1888 -- if the prefix itself was explicitly initialized.
1890 -- Discriminants are always considered initialized
1892 elsif Ekind (Ent) = E_Discriminant then
1895 -- An explicitly initialized component is certainly initialized
1897 elsif Nkind (Parent (Ent)) = N_Component_Declaration
1898 and then Present (Expression (Parent (Ent)))
1902 -- A fully initialized component is initialized
1904 elsif Is_OK_Fully_Initialized then
1908 -- If none of those cases apply, check the record type prefix
1910 Check_Unset_Reference (Pref);
1913 -- For type conversions or qualifications examine the expression
1915 when N_Type_Conversion | N_Qualified_Expression =>
1916 Check_Unset_Reference (Expression (N));
1918 -- For explicit dereference, always check prefix, which will generate
1919 -- an unset reference (since this is a case of dereferencing null).
1921 when N_Explicit_Dereference =>
1922 Check_Unset_Reference (Prefix (N));
1924 -- All other cases are not cases of an unset reference
1930 end Check_Unset_Reference;
1932 ------------------------
1933 -- Check_Unused_Withs --
1934 ------------------------
1936 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
1942 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
1943 -- This is needed for checking the special renaming case
1945 procedure Check_One_Unit (Unit : Unit_Number_Type);
1946 -- Subsidiary procedure, performs checks for specified unit
1948 --------------------
1949 -- Check_One_Unit --
1950 --------------------
1952 procedure Check_One_Unit (Unit : Unit_Number_Type) is
1953 Is_Visible_Renaming : Boolean := False;
1956 procedure Check_Inner_Package (Pack : Entity_Id);
1957 -- Pack is a package local to a unit in a with_clause. Both the unit
1958 -- and Pack are referenced. If none of the entities in Pack are
1959 -- referenced, then the only occurrence of Pack is in a USE clause
1960 -- or a pragma, and a warning is worthwhile as well.
1962 function Check_System_Aux return Boolean;
1963 -- Before giving a warning on a with_clause for System, check wheter
1964 -- a system extension is present.
1966 function Find_Package_Renaming
1968 L : Entity_Id) return Entity_Id;
1969 -- The only reference to a context unit may be in a renaming
1970 -- declaration. If this renaming declares a visible entity, do not
1971 -- warn that the context clause could be moved to the body, because
1972 -- the renaming may be intended to re-export the unit.
1974 function Has_Visible_Entities (P : Entity_Id) return Boolean;
1975 -- This function determines if a package has any visible entities.
1976 -- True is returned if there is at least one declared visible entity,
1977 -- otherwise False is returned (e.g. case of only pragmas present).
1979 -------------------------
1980 -- Check_Inner_Package --
1981 -------------------------
1983 procedure Check_Inner_Package (Pack : Entity_Id) is
1985 Un : constant Node_Id := Sinfo.Unit (Cnode);
1987 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
1988 -- If N is a use_clause for Pack, emit warning
1990 procedure Check_Use_Clauses is new
1991 Traverse_Proc (Check_Use_Clause);
1993 ----------------------
1994 -- Check_Use_Clause --
1995 ----------------------
1997 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2001 if Nkind (N) = N_Use_Package_Clause then
2002 Nam := First (Names (N));
2003 while Present (Nam) loop
2004 if Entity (Nam) = Pack then
2005 Error_Msg_Qual_Level := 1;
2007 ("?no entities of package& are referenced!",
2009 Error_Msg_Qual_Level := 0;
2017 end Check_Use_Clause;
2019 -- Start of processing for Check_Inner_Package
2022 E := First_Entity (Pack);
2023 while Present (E) loop
2024 if Referenced_Check_Spec (E) then
2031 -- No entities of the package are referenced. Check whether the
2032 -- reference to the package itself is a use clause, and if so
2033 -- place a warning on it.
2035 Check_Use_Clauses (Un);
2036 end Check_Inner_Package;
2038 ----------------------
2039 -- Check_System_Aux --
2040 ----------------------
2042 function Check_System_Aux return Boolean is
2046 if Chars (Lunit) = Name_System
2047 and then Scope (Lunit) = Standard_Standard
2048 and then Present_System_Aux
2050 Ent := First_Entity (System_Aux_Id);
2051 while Present (Ent) loop
2052 if Referenced_Check_Spec (Ent) then
2061 end Check_System_Aux;
2063 ---------------------------
2064 -- Find_Package_Renaming --
2065 ---------------------------
2067 function Find_Package_Renaming
2069 L : Entity_Id) return Entity_Id
2075 Is_Visible_Renaming := False;
2077 E1 := First_Entity (P);
2078 while Present (E1) loop
2079 if Ekind (E1) = E_Package
2080 and then Renamed_Object (E1) = L
2082 Is_Visible_Renaming := not Is_Hidden (E1);
2085 elsif Ekind (E1) = E_Package
2086 and then No (Renamed_Object (E1))
2087 and then not Is_Generic_Instance (E1)
2089 R := Find_Package_Renaming (E1, L);
2092 Is_Visible_Renaming := not Is_Hidden (R);
2101 end Find_Package_Renaming;
2103 --------------------------
2104 -- Has_Visible_Entities --
2105 --------------------------
2107 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2111 -- If unit in context is not a package, it is a subprogram that
2112 -- is not called or a generic unit that is not instantiated
2113 -- in the current unit, and warning is appropriate.
2115 if Ekind (P) /= E_Package then
2119 -- If unit comes from a limited_with clause, look for declaration
2120 -- of shadow entities.
2122 if Present (Limited_View (P)) then
2123 E := First_Entity (Limited_View (P));
2125 E := First_Entity (P);
2129 and then E /= First_Private_Entity (P)
2131 if Comes_From_Source (E)
2132 or else Present (Limited_View (P))
2141 end Has_Visible_Entities;
2143 -- Start of processing for Check_One_Unit
2146 Cnode := Cunit (Unit);
2148 -- Only do check in units that are part of the extended main unit.
2149 -- This is actually a necessary restriction, because in the case of
2150 -- subprogram acting as its own specification, there can be with's in
2151 -- subunits that we will not see.
2153 if not In_Extended_Main_Source_Unit (Cnode) then
2156 -- In configurable run time mode, we remove the bodies of non-inlined
2157 -- subprograms, which may lead to spurious warnings, which are
2158 -- clearly undesirable.
2160 elsif Configurable_Run_Time_Mode
2161 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2166 -- Loop through context items in this unit
2168 Item := First (Context_Items (Cnode));
2169 while Present (Item) loop
2170 if Nkind (Item) = N_With_Clause
2171 and then not Implicit_With (Item)
2172 and then In_Extended_Main_Source_Unit (Item)
2174 Lunit := Entity (Name (Item));
2176 -- Check if this unit is referenced (skip the check if this
2177 -- is explicitly marked by a pragma Unreferenced).
2179 if not Referenced (Lunit)
2180 and then not Has_Unreferenced (Lunit)
2182 -- Suppress warnings in internal units if not in -gnatg mode
2183 -- (these would be junk warnings for an application program,
2184 -- since they refer to problems in internal units).
2187 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2189 -- Here we definitely have a non-referenced unit. If it
2190 -- is the special call for a spec unit, then just set the
2191 -- flag to be read later.
2193 if Unit = Spec_Unit then
2194 Set_Unreferenced_In_Spec (Item);
2196 -- Otherwise simple unreferenced message, but skip this
2197 -- if no visible entities, because that is most likely a
2198 -- case where warning would be false positive (e.g. a
2199 -- package with only a linker options pragma and nothing
2200 -- else or a pragma elaborate with a body library task).
2202 elsif Has_Visible_Entities (Entity (Name (Item))) then
2204 ("?unit& is not referenced!", Name (Item));
2208 -- If main unit is a renaming of this unit, then we consider
2209 -- the with to be OK (obviously it is needed in this case!)
2210 -- This may be transitive: the unit in the with_clause may
2211 -- itself be a renaming, in which case both it and the main
2212 -- unit rename the same ultimate package.
2214 elsif Present (Renamed_Entity (Munite))
2216 (Renamed_Entity (Munite) = Lunit
2217 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2221 -- If this unit is referenced, and it is a package, we do
2222 -- another test, to see if any of the entities in the package
2223 -- are referenced. If none of the entities are referenced, we
2224 -- still post a warning. This occurs if the only use of the
2225 -- package is in a use clause, or in a package renaming
2226 -- declaration. This check is skipped for packages that are
2227 -- renamed in a spec, since the entities in such a package are
2228 -- visible to clients via the renaming.
2230 elsif Ekind (Lunit) = E_Package
2231 and then not Renamed_In_Spec (Lunit)
2233 -- If Is_Instantiated is set, it means that the package is
2234 -- implicitly instantiated (this is the case of parent
2235 -- instance or an actual for a generic package formal), and
2236 -- this counts as a reference.
2238 if Is_Instantiated (Lunit) then
2241 -- If no entities in package, and there is a pragma
2242 -- Elaborate_Body present, then assume that this with is
2243 -- done for purposes of this elaboration.
2245 elsif No (First_Entity (Lunit))
2246 and then Has_Pragma_Elaborate_Body (Lunit)
2250 -- Otherwise see if any entities have been referenced
2253 if Limited_Present (Item) then
2254 Ent := First_Entity (Limited_View (Lunit));
2256 Ent := First_Entity (Lunit);
2260 -- No more entities, and we did not find one that was
2261 -- referenced. Means we have a definite case of a with
2262 -- none of whose entities was referenced.
2266 -- If in spec, just set the flag
2268 if Unit = Spec_Unit then
2269 Set_No_Entities_Ref_In_Spec (Item);
2271 elsif Check_System_Aux then
2274 -- Else give the warning
2278 Has_Unreferenced (Entity (Name (Item)))
2281 ("?no entities of & are referenced!",
2285 -- Look for renamings of this package, and flag
2286 -- them as well. If the original package has
2287 -- warnings off, we suppress the warning on the
2288 -- renaming as well.
2290 Pack := Find_Package_Renaming (Munite, Lunit);
2293 and then not Has_Warnings_Off (Lunit)
2294 and then not Has_Unreferenced (Pack)
2297 ("?no entities of & are referenced!",
2298 Unit_Declaration_Node (Pack),
2305 -- Case of entity being referenced. The reference may
2306 -- come from a limited_with_clause, in which case the
2307 -- limited view of the entity carries the flag.
2309 elsif Referenced_Check_Spec (Ent)
2310 or else Referenced_As_LHS_Check_Spec (Ent)
2311 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2313 (From_With_Type (Ent)
2314 and then Is_Incomplete_Type (Ent)
2315 and then Present (Non_Limited_View (Ent))
2316 and then Referenced (Non_Limited_View (Ent)))
2318 -- This means that the with is indeed fine, in that
2319 -- it is definitely needed somewhere, and we can
2320 -- quit worrying about this one...
2322 -- Except for one little detail: if either of the
2323 -- flags was set during spec processing, this is
2324 -- where we complain that the with could be moved
2325 -- from the spec. If the spec contains a visible
2326 -- renaming of the package, inhibit warning to move
2327 -- with_clause to body.
2329 if Ekind (Munite) = E_Package_Body then
2331 Find_Package_Renaming
2332 (Spec_Entity (Munite), Lunit);
2335 if Unreferenced_In_Spec (Item) then
2337 ("?unit& is not referenced in spec!",
2340 elsif No_Entities_Ref_In_Spec (Item) then
2342 ("?no entities of & are referenced in spec!",
2346 if Ekind (Ent) = E_Package then
2347 Check_Inner_Package (Ent);
2353 if not Is_Visible_Renaming then
2354 Error_Msg_N -- CODEFIX
2355 ("\?with clause might be moved to body!",
2361 -- Move to next entity to continue search
2369 -- For a generic package, the only interesting kind of
2370 -- reference is an instantiation, since entities cannot be
2371 -- referenced directly.
2373 elsif Is_Generic_Unit (Lunit) then
2375 -- Unit was never instantiated, set flag for case of spec
2376 -- call, or give warning for normal call.
2378 if not Is_Instantiated (Lunit) then
2379 if Unit = Spec_Unit then
2380 Set_Unreferenced_In_Spec (Item);
2382 Error_Msg_N -- CODEFIX
2383 ("?unit& is never instantiated!", Name (Item));
2386 -- If unit was indeed instantiated, make sure that flag is
2387 -- not set showing it was uninstantiated in the spec, and if
2388 -- so, give warning.
2390 elsif Unreferenced_In_Spec (Item) then
2392 ("?unit& is not instantiated in spec!", Name (Item));
2393 Error_Msg_N -- CODEFIX
2394 ("\?with clause can be moved to body!", Name (Item));
2403 -- Start of processing for Check_Unused_Withs
2406 if not Opt.Check_Withs
2407 or else Operating_Mode = Check_Syntax
2412 -- Flag any unused with clauses, but skip this step if we are compiling
2413 -- a subunit on its own, since we do not have enough information to
2414 -- determine whether with's are used. We will get the relevant warnings
2415 -- when we compile the parent. This is the normal style of GNAT
2416 -- compilation in any case.
2418 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2422 -- Process specified units
2424 if Spec_Unit = No_Unit then
2426 -- For main call, check all units
2428 for Unit in Main_Unit .. Last_Unit loop
2429 Check_One_Unit (Unit);
2433 -- For call for spec, check only the spec
2435 Check_One_Unit (Spec_Unit);
2437 end Check_Unused_Withs;
2439 ---------------------------------
2440 -- Generic_Package_Spec_Entity --
2441 ---------------------------------
2443 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2447 if Is_Package_Body_Entity (E) then
2453 if S = Standard_Standard then
2456 elsif Ekind (S) = E_Generic_Package then
2459 elsif Ekind (S) = E_Package then
2467 end Generic_Package_Spec_Entity;
2469 ----------------------
2470 -- Goto_Spec_Entity --
2471 ----------------------
2473 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2476 and then Present (Spec_Entity (E))
2478 return Spec_Entity (E);
2482 end Goto_Spec_Entity;
2484 --------------------------------------
2485 -- Has_Pragma_Unmodified_Check_Spec --
2486 --------------------------------------
2488 function Has_Pragma_Unmodified_Check_Spec
2489 (E : Entity_Id) return Boolean
2492 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2494 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2495 -- to mess with Unmodified flags on both body and spec entities.
2497 return Has_Unmodified (E)
2499 Has_Unmodified (Spec_Entity (E));
2502 return Has_Unmodified (E);
2504 end Has_Pragma_Unmodified_Check_Spec;
2506 ----------------------------------------
2507 -- Has_Pragma_Unreferenced_Check_Spec --
2508 ----------------------------------------
2510 function Has_Pragma_Unreferenced_Check_Spec
2511 (E : Entity_Id) return Boolean
2514 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2516 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2517 -- to mess with flags on both entities.
2519 return Has_Unreferenced (E)
2521 Has_Unreferenced (Spec_Entity (E));
2524 return Has_Unreferenced (E);
2526 end Has_Pragma_Unreferenced_Check_Spec;
2532 procedure Initialize is
2534 Warnings_Off_Pragmas.Init;
2535 Unreferenced_Entities.Init;
2536 In_Out_Warnings.Init;
2539 ------------------------------------
2540 -- Never_Set_In_Source_Check_Spec --
2541 ------------------------------------
2543 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2545 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2546 return Never_Set_In_Source (E)
2548 Never_Set_In_Source (Spec_Entity (E));
2550 return Never_Set_In_Source (E);
2552 end Never_Set_In_Source_Check_Spec;
2554 -------------------------------------
2555 -- Operand_Has_Warnings_Suppressed --
2556 -------------------------------------
2558 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2560 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2561 -- Function used to check one node to see if it is or was originally
2562 -- a reference to an entity for which Warnings are off. If so, Abandon
2563 -- is returned, otherwise OK_Orig is returned to continue the traversal
2564 -- of the original expression.
2566 function Traverse is new Traverse_Func (Check_For_Warnings);
2567 -- Function used to traverse tree looking for warnings
2569 ------------------------
2570 -- Check_For_Warnings --
2571 ------------------------
2573 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2574 R : constant Node_Id := Original_Node (N);
2577 if Nkind (R) in N_Has_Entity
2578 and then Present (Entity (R))
2579 and then Has_Warnings_Off (Entity (R))
2585 end Check_For_Warnings;
2587 -- Start of processing for Operand_Has_Warnings_Suppressed
2590 return Traverse (N) = Abandon;
2592 -- If any exception occurs, then something has gone wrong, and this is
2593 -- only a minor aesthetic issue anyway, so just say we did not find what
2594 -- we are looking for, rather than blow up.
2599 end Operand_Has_Warnings_Suppressed;
2601 -----------------------------------------
2602 -- Output_Non_Modified_In_Out_Warnings --
2603 -----------------------------------------
2605 procedure Output_Non_Modifed_In_Out_Warnings is
2607 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2608 -- Given a formal parameter entity E, determines if there is a reason to
2609 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2610 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2611 -- if we have seen the address of the subprogram being taken, or if the
2612 -- subprogram is used as a generic actual (in the latter cases the
2613 -- context may force use of IN OUT, even if the parameter is not
2614 -- modifies for this particular case.
2616 -----------------------
2617 -- No_Warn_On_In_Out --
2618 -----------------------
2620 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2621 S : constant Entity_Id := Scope (E);
2622 SE : constant Entity_Id := Spec_Entity (E);
2625 -- Do not warn if address is taken, since funny business may be going
2626 -- on in treating the parameter indirectly as IN OUT.
2628 if Address_Taken (S)
2629 or else (Present (SE) and then Address_Taken (Scope (SE)))
2633 -- Do not warn if used as a generic actual, since the generic may be
2634 -- what is forcing the use of an "unnecessary" IN OUT.
2636 elsif Used_As_Generic_Actual (S)
2637 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2641 -- Else test warnings off
2643 elsif Warnings_Off_Check_Spec (S) then
2646 -- All tests for suppressing warning failed
2651 end No_Warn_On_In_Out;
2653 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2656 -- Loop through entities for which a warning may be needed
2658 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2660 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2663 -- Suppress warning in specific cases (see details in comments for
2664 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2666 if Has_Pragma_Unmodified_Check_Spec (E1)
2667 or else No_Warn_On_In_Out (E1)
2671 -- Here we generate the warning
2674 -- If -gnatwc is set then output message that we could be IN
2676 if not Is_Trivial_Subprogram (Scope (E1)) then
2677 if Warn_On_Constant then
2679 ("?formal parameter & is not modified!", E1);
2681 ("\?mode could be IN instead of `IN OUT`!", E1);
2683 -- We do not generate warnings for IN OUT parameters
2684 -- unless we have at least -gnatwu. This is deliberately
2685 -- inconsistent with the treatment of variables, but
2686 -- otherwise we get too many unexpected warnings in
2689 elsif Check_Unreferenced then
2690 Error_Msg_N ("?formal parameter& is read but "
2691 & "never assigned!", E1);
2695 -- Kill any other warnings on this entity, since this is the
2696 -- one that should dominate any other unreferenced warning.
2698 Set_Warnings_Off (E1);
2702 end Output_Non_Modifed_In_Out_Warnings;
2704 ----------------------------------------
2705 -- Output_Obsolescent_Entity_Warnings --
2706 ----------------------------------------
2708 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2709 P : constant Node_Id := Parent (N);
2715 -- Do not output message if we are the scope of standard. This means
2716 -- we have a reference from a context clause from when it is originally
2717 -- processed, and that's too early to tell whether it is an obsolescent
2718 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2719 -- sure that we have a later call when the scope is available. This test
2720 -- also eliminates all messages for use clauses, which is fine (we do
2721 -- not want messages for use clauses, since they are always redundant
2722 -- with respect to the associated with clause).
2724 if S = Standard_Standard then
2728 -- Do not output message if we are in scope of an obsolescent package
2732 if Is_Obsolescent (S) then
2737 exit when S = Standard_Standard;
2740 -- Here we will output the message
2742 Error_Msg_Sloc := Sloc (E);
2744 -- Case of with clause
2746 if Nkind (P) = N_With_Clause then
2747 if Ekind (E) = E_Package then
2749 ("?with of obsolescent package& declared#", N, E);
2750 elsif Ekind (E) = E_Procedure then
2752 ("?with of obsolescent procedure& declared#", N, E);
2755 ("?with of obsolescent function& declared#", N, E);
2758 -- If we do not have a with clause, then ignore any reference to an
2759 -- obsolescent package name. We only want to give the one warning of
2760 -- withing the package, not one each time it is used to qualify.
2762 elsif Ekind (E) = E_Package then
2765 -- Procedure call statement
2767 elsif Nkind (P) = N_Procedure_Call_Statement then
2769 ("?call to obsolescent procedure& declared#", N, E);
2773 elsif Nkind (P) = N_Function_Call then
2775 ("?call to obsolescent function& declared#", N, E);
2777 -- Reference to obsolescent type
2779 elsif Is_Type (E) then
2781 ("?reference to obsolescent type& declared#", N, E);
2783 -- Reference to obsolescent component
2785 elsif Ekind (E) = E_Component
2786 or else Ekind (E) = E_Discriminant
2789 ("?reference to obsolescent component& declared#", N, E);
2791 -- Reference to obsolescent variable
2793 elsif Ekind (E) = E_Variable then
2795 ("?reference to obsolescent variable& declared#", N, E);
2797 -- Reference to obsolescent constant
2799 elsif Ekind (E) = E_Constant
2800 or else Ekind (E) in Named_Kind
2803 ("?reference to obsolescent constant& declared#", N, E);
2805 -- Reference to obsolescent enumeration literal
2807 elsif Ekind (E) = E_Enumeration_Literal then
2809 ("?reference to obsolescent enumeration literal& declared#", N, E);
2811 -- Generic message for any other case we missed
2815 ("?reference to obsolescent entity& declared#", N, E);
2818 -- Output additional warning if present
2820 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2821 if Obsolescent_Warnings.Table (J).Ent = E then
2822 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2823 Error_Msg_Strlen := Name_Len;
2824 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2825 Error_Msg_N ("\\?~", N);
2829 end Output_Obsolescent_Entity_Warnings;
2831 ----------------------------------
2832 -- Output_Unreferenced_Messages --
2833 ----------------------------------
2835 procedure Output_Unreferenced_Messages is
2837 for J in Unreferenced_Entities.First ..
2838 Unreferenced_Entities.Last
2840 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2842 end Output_Unreferenced_Messages;
2844 -----------------------------------------
2845 -- Output_Unused_Warnings_Off_Warnings --
2846 -----------------------------------------
2848 procedure Output_Unused_Warnings_Off_Warnings is
2850 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2852 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2853 N : Node_Id renames Wentry.N;
2854 E : Node_Id renames Wentry.E;
2857 -- Turn off Warnings_Off, or we won't get the warning!
2859 Set_Warnings_Off (E, False);
2861 -- Nothing to do if pragma was used to suppress a general warning
2863 if Warnings_Off_Used (E) then
2866 -- If pragma was used both in unmodified and unreferenced contexts
2867 -- then that's as good as the general case, no warning.
2869 elsif Warnings_Off_Used_Unmodified (E)
2871 Warnings_Off_Used_Unreferenced (E)
2875 -- Used only in context where Unmodified would have worked
2877 elsif Warnings_Off_Used_Unmodified (E) then
2879 ("?could use Unmodified instead of "
2880 & "Warnings Off for &", Pragma_Identifier (N), E);
2882 -- Used only in context where Unreferenced would have worked
2884 elsif Warnings_Off_Used_Unreferenced (E) then
2886 ("?could use Unreferenced instead of "
2887 & "Warnings Off for &", Pragma_Identifier (N), E);
2893 ("?pragma Warnings Off for & unused, "
2894 & "could be omitted", N, E);
2898 end Output_Unused_Warnings_Off_Warnings;
2900 ---------------------------
2901 -- Referenced_Check_Spec --
2902 ---------------------------
2904 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
2906 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2907 return Referenced (E) or else Referenced (Spec_Entity (E));
2909 return Referenced (E);
2911 end Referenced_Check_Spec;
2913 ----------------------------------
2914 -- Referenced_As_LHS_Check_Spec --
2915 ----------------------------------
2917 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
2919 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2920 return Referenced_As_LHS (E)
2921 or else Referenced_As_LHS (Spec_Entity (E));
2923 return Referenced_As_LHS (E);
2925 end Referenced_As_LHS_Check_Spec;
2927 --------------------------------------------
2928 -- Referenced_As_Out_Parameter_Check_Spec --
2929 --------------------------------------------
2931 function Referenced_As_Out_Parameter_Check_Spec
2932 (E : Entity_Id) return Boolean
2935 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2936 return Referenced_As_Out_Parameter (E)
2937 or else Referenced_As_Out_Parameter (Spec_Entity (E));
2939 return Referenced_As_Out_Parameter (E);
2941 end Referenced_As_Out_Parameter_Check_Spec;
2943 ----------------------------
2944 -- Set_Dot_Warning_Switch --
2945 ----------------------------
2947 function Set_Dot_Warning_Switch (C : Character) return Boolean is
2951 Warn_On_Assertion_Failure := True;
2954 Warn_On_Assertion_Failure := False;
2957 Warn_On_Biased_Representation := True;
2960 Warn_On_Biased_Representation := False;
2963 Warn_On_Unrepped_Components := True;
2966 Warn_On_Unrepped_Components := False;
2969 Address_Clause_Overlay_Warnings := True;
2970 Check_Unreferenced := True;
2971 Check_Unreferenced_Formals := True;
2972 Check_Withs := True;
2973 Constant_Condition_Warnings := True;
2974 Elab_Warnings := True;
2975 Implementation_Unit_Warnings := True;
2976 Ineffective_Inline_Warnings := True;
2977 Warn_On_Ada_2005_Compatibility := True;
2978 Warn_On_All_Unread_Out_Parameters := True;
2979 Warn_On_Assertion_Failure := True;
2980 Warn_On_Assumed_Low_Bound := True;
2981 Warn_On_Bad_Fixed_Value := True;
2982 Warn_On_Biased_Representation := True;
2983 Warn_On_Constant := True;
2984 Warn_On_Deleted_Code := True;
2985 Warn_On_Dereference := True;
2986 Warn_On_Export_Import := True;
2987 Warn_On_Hiding := True;
2988 Warn_On_Modified_Unread := True;
2989 Warn_On_No_Value_Assigned := True;
2990 Warn_On_Non_Local_Exception := True;
2991 Warn_On_Object_Renames_Function := True;
2992 Warn_On_Obsolescent_Feature := True;
2993 Warn_On_Questionable_Missing_Parens := True;
2994 Warn_On_Redundant_Constructs := True;
2995 Warn_On_Unchecked_Conversion := True;
2996 Warn_On_Unrecognized_Pragma := True;
2997 Warn_On_Unrepped_Components := True;
2998 Warn_On_Warnings_Off := True;
3001 Warn_On_All_Unread_Out_Parameters := True;
3004 Warn_On_All_Unread_Out_Parameters := False;
3007 Warn_On_Parameter_Order := True;
3010 Warn_On_Parameter_Order := False;
3013 Warn_On_Object_Renames_Function := True;
3016 Warn_On_Object_Renames_Function := False;
3019 Warn_On_Warnings_Off := True;
3022 Warn_On_Warnings_Off := False;
3025 Warn_On_Non_Local_Exception := True;
3028 Warn_On_Non_Local_Exception := False;
3029 No_Warn_On_Non_Local_Exception := True;
3036 end Set_Dot_Warning_Switch;
3038 ------------------------
3039 -- Set_Warning_Switch --
3040 ------------------------
3042 function Set_Warning_Switch (C : Character) return Boolean is
3046 Check_Unreferenced := True;
3047 Check_Unreferenced_Formals := True;
3048 Check_Withs := True;
3049 Constant_Condition_Warnings := True;
3050 Implementation_Unit_Warnings := True;
3051 Ineffective_Inline_Warnings := True;
3052 Warn_On_Ada_2005_Compatibility := True;
3053 Warn_On_Assertion_Failure := True;
3054 Warn_On_Assumed_Low_Bound := True;
3055 Warn_On_Bad_Fixed_Value := True;
3056 Warn_On_Biased_Representation := True;
3057 Warn_On_Constant := True;
3058 Warn_On_Export_Import := True;
3059 Warn_On_Modified_Unread := True;
3060 Warn_On_No_Value_Assigned := True;
3061 Warn_On_Non_Local_Exception := True;
3062 Warn_On_Object_Renames_Function := True;
3063 Warn_On_Obsolescent_Feature := True;
3064 Warn_On_Parameter_Order := True;
3065 Warn_On_Questionable_Missing_Parens := True;
3066 Warn_On_Redundant_Constructs := True;
3067 Warn_On_Unchecked_Conversion := True;
3068 Warn_On_Unrecognized_Pragma := True;
3069 Warn_On_Unrepped_Components := True;
3072 Check_Unreferenced := False;
3073 Check_Unreferenced_Formals := False;
3074 Check_Withs := False;
3075 Constant_Condition_Warnings := False;
3076 Elab_Warnings := False;
3077 Implementation_Unit_Warnings := False;
3078 Ineffective_Inline_Warnings := False;
3079 Warn_On_Ada_2005_Compatibility := False;
3080 Warn_On_Assertion_Failure := False;
3081 Warn_On_Assumed_Low_Bound := False;
3082 Warn_On_Bad_Fixed_Value := False;
3083 Warn_On_Biased_Representation := False;
3084 Warn_On_Constant := False;
3085 Warn_On_Deleted_Code := False;
3086 Warn_On_Dereference := False;
3087 Warn_On_Export_Import := False;
3088 Warn_On_Hiding := False;
3089 Warn_On_Modified_Unread := False;
3090 Warn_On_No_Value_Assigned := False;
3091 Warn_On_Non_Local_Exception := False;
3092 Warn_On_Obsolescent_Feature := False;
3093 Warn_On_All_Unread_Out_Parameters := False;
3094 Warn_On_Parameter_Order := False;
3095 Warn_On_Questionable_Missing_Parens := False;
3096 Warn_On_Redundant_Constructs := False;
3097 Warn_On_Object_Renames_Function := False;
3098 Warn_On_Unchecked_Conversion := False;
3099 Warn_On_Unrecognized_Pragma := False;
3100 Warn_On_Unrepped_Components := False;
3101 Warn_On_Warnings_Off := False;
3103 No_Warn_On_Non_Local_Exception := True;
3106 Warn_On_Bad_Fixed_Value := True;
3109 Warn_On_Bad_Fixed_Value := False;
3112 Constant_Condition_Warnings := True;
3115 Constant_Condition_Warnings := False;
3118 Warn_On_Dereference := True;
3121 Warn_On_Dereference := False;
3124 Warning_Mode := Treat_As_Error;
3127 Check_Unreferenced_Formals := True;
3130 Check_Unreferenced_Formals := False;
3133 Warn_On_Unrecognized_Pragma := True;
3136 Warn_On_Unrecognized_Pragma := False;
3139 Warn_On_Hiding := True;
3142 Warn_On_Hiding := False;
3145 Implementation_Unit_Warnings := True;
3148 Implementation_Unit_Warnings := False;
3151 Warn_On_Obsolescent_Feature := True;
3154 Warn_On_Obsolescent_Feature := False;
3157 Warn_On_Constant := True;
3160 Warn_On_Constant := False;
3163 Elab_Warnings := True;
3166 Elab_Warnings := False;
3169 Warn_On_Modified_Unread := True;
3172 Warn_On_Modified_Unread := False;
3175 Warning_Mode := Normal;
3178 Address_Clause_Overlay_Warnings := True;
3181 Address_Clause_Overlay_Warnings := False;
3184 Ineffective_Inline_Warnings := True;
3187 Ineffective_Inline_Warnings := False;
3190 Warn_On_Questionable_Missing_Parens := True;
3193 Warn_On_Questionable_Missing_Parens := False;
3196 Warn_On_Redundant_Constructs := True;
3199 Warn_On_Redundant_Constructs := False;
3202 Warning_Mode := Suppress;
3205 Warn_On_Deleted_Code := True;
3208 Warn_On_Deleted_Code := False;
3211 Check_Unreferenced := True;
3212 Check_Withs := True;
3213 Check_Unreferenced_Formals := True;
3216 Check_Unreferenced := False;
3217 Check_Withs := False;
3218 Check_Unreferenced_Formals := False;
3221 Warn_On_No_Value_Assigned := True;
3224 Warn_On_No_Value_Assigned := False;
3227 Warn_On_Assumed_Low_Bound := True;
3230 Warn_On_Assumed_Low_Bound := False;
3233 Warn_On_Export_Import := True;
3236 Warn_On_Export_Import := False;
3239 Warn_On_Ada_2005_Compatibility := True;
3242 Warn_On_Ada_2005_Compatibility := False;
3245 Warn_On_Unchecked_Conversion := True;
3248 Warn_On_Unchecked_Conversion := False;
3255 end Set_Warning_Switch;
3257 -----------------------------
3258 -- Warn_On_Known_Condition --
3259 -----------------------------
3261 procedure Warn_On_Known_Condition (C : Node_Id) is
3264 procedure Track (N : Node_Id; Loc : Node_Id);
3265 -- Adds continuation warning(s) pointing to reason (assignment or test)
3266 -- for the operand of the conditional having a known value (or at least
3267 -- enough is known about the value to issue the warning). N is the node
3268 -- which is judged to have a known value. Loc is the warning location.
3274 procedure Track (N : Node_Id; Loc : Node_Id) is
3275 Nod : constant Node_Id := Original_Node (N);
3278 if Nkind (Nod) in N_Op_Compare then
3279 Track (Left_Opnd (Nod), Loc);
3280 Track (Right_Opnd (Nod), Loc);
3282 elsif Is_Entity_Name (Nod)
3283 and then Is_Object (Entity (Nod))
3286 CV : constant Node_Id := Current_Value (Entity (Nod));
3289 if Present (CV) then
3290 Error_Msg_Sloc := Sloc (CV);
3292 if Nkind (CV) not in N_Subexpr then
3293 Error_Msg_N ("\\?(see test #)", Loc);
3295 elsif Nkind (Parent (CV)) =
3296 N_Case_Statement_Alternative
3298 Error_Msg_N ("\\?(see case alternative #)", Loc);
3301 Error_Msg_N ("\\?(see assignment #)", Loc);
3308 -- Start of processing for Warn_On_Known_Condition
3311 -- Argument replacement in an inlined body can make conditions static.
3312 -- Do not emit warnings in this case.
3314 if In_Inlined_Body then
3318 if Constant_Condition_Warnings
3319 and then Nkind (C) = N_Identifier
3321 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3322 and then Comes_From_Source (Original_Node (C))
3323 and then not In_Instance
3325 -- See if this is in a statement or a declaration
3329 -- If tree is not attached, do not issue warning (this is very
3330 -- peculiar, and probably arises from some other error condition)
3335 -- If we are in a declaration, then no warning, since in practice
3336 -- conditionals in declarations are used for intended tests which
3337 -- may be known at compile time, e.g. things like
3339 -- x : constant Integer := 2 + (Word'Size = 32);
3341 -- And a warning is annoying in such cases
3343 elsif Nkind (P) in N_Declaration
3345 Nkind (P) in N_Later_Decl_Item
3349 -- Don't warn in assert or check pragma, since presumably tests in
3350 -- such a context are very definitely intended, and might well be
3351 -- known at compile time. Note that we have to test the original
3352 -- node, since assert pragmas get rewritten at analysis time.
3354 elsif Nkind (Original_Node (P)) = N_Pragma
3355 and then (Pragma_Name (Original_Node (P)) = Name_Assert
3357 Pragma_Name (Original_Node (P)) = Name_Check)
3362 exit when Is_Statement (P);
3366 -- Here we issue the warning unless some sub-operand has warnings
3367 -- set off, in which case we suppress the warning for the node. If
3368 -- the original expression is an inequality, it has been expanded
3369 -- into a negation, and the value of the original expression is the
3370 -- negation of the equality. If the expression is an entity that
3371 -- appears within a negation, it is clearer to flag the negation
3372 -- itself, and report on its constant value.
3374 if not Operand_Has_Warnings_Suppressed (C) then
3376 True_Branch : Boolean := Entity (C) = Standard_True;
3377 Cond : Node_Id := C;
3380 if Present (Parent (C))
3381 and then Nkind (Parent (C)) = N_Op_Not
3383 True_Branch := not True_Branch;
3388 if Is_Entity_Name (Original_Node (C))
3389 and then Nkind (Cond) /= N_Op_Not
3392 ("object & is always True?", Cond, Original_Node (C));
3393 Track (Original_Node (C), Cond);
3396 Error_Msg_N ("condition is always True?", Cond);
3401 Error_Msg_N ("condition is always False?", Cond);
3407 end Warn_On_Known_Condition;
3409 ---------------------------------------
3410 -- Warn_On_Modified_As_Out_Parameter --
3411 ---------------------------------------
3413 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3416 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3417 or else Warn_On_All_Unread_Out_Parameters;
3418 end Warn_On_Modified_As_Out_Parameter;
3420 ------------------------------
3421 -- Warn_On_Suspicious_Index --
3422 ------------------------------
3424 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3427 -- Set to lower bound for a suspicious type
3430 -- Entity for array reference
3435 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3436 -- Tests to see if Typ is a type for which we may have a suspicious
3437 -- index, namely an unconstrained array type, whose lower bound is
3438 -- either zero or one. If so, True is returned, and Low_Bound is set
3439 -- to this lower bound. If not, False is returned, and Low_Bound is
3440 -- undefined on return.
3442 -- For now, we limit this to standard string types, so any other
3443 -- unconstrained types return False. We may change our minds on this
3444 -- later on, but strings seem the most important case.
3446 procedure Test_Suspicious_Index;
3447 -- Test if index is of suspicious type and if so, generate warning
3449 ------------------------
3450 -- Is_Suspicious_Type --
3451 ------------------------
3453 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3457 if Is_Array_Type (Typ)
3458 and then not Is_Constrained (Typ)
3459 and then Number_Dimensions (Typ) = 1
3460 and then (Root_Type (Typ) = Standard_String
3462 Root_Type (Typ) = Standard_Wide_String
3464 Root_Type (Typ) = Standard_Wide_Wide_String)
3465 and then not Has_Warnings_Off (Typ)
3467 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3469 if Compile_Time_Known_Value (LB) then
3470 Low_Bound := Expr_Value (LB);
3471 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3476 end Is_Suspicious_Type;
3478 ---------------------------
3479 -- Test_Suspicious_Index --
3480 ---------------------------
3482 procedure Test_Suspicious_Index is
3484 function Length_Reference (N : Node_Id) return Boolean;
3485 -- Check if node N is of the form Name'Length
3488 -- Generate first warning line
3490 ----------------------
3491 -- Length_Reference --
3492 ----------------------
3494 function Length_Reference (N : Node_Id) return Boolean is
3495 R : constant Node_Id := Original_Node (N);
3498 Nkind (R) = N_Attribute_Reference
3499 and then Attribute_Name (R) = Name_Length
3500 and then Is_Entity_Name (Prefix (R))
3501 and then Entity (Prefix (R)) = Ent;
3502 end Length_Reference;
3510 Error_Msg_Uint_1 := Low_Bound;
3511 Error_Msg_FE ("?index for& may assume lower bound of^", X, Ent);
3514 -- Start of processing for Test_Suspicious_Index
3517 -- Nothing to do if subscript does not come from source (we don't
3518 -- want to give garbage warnings on compiler expanded code, e.g. the
3519 -- loops generated for slice assignments. Such junk warnings would
3520 -- be placed on source constructs with no subscript in sight!)
3522 if not Comes_From_Source (Original_Node (X)) then
3526 -- Case where subscript is a constant integer
3528 if Nkind (X) = N_Integer_Literal then
3531 -- Case where original form of subscript is an integer literal
3533 if Nkind (Original_Node (X)) = N_Integer_Literal then
3534 if Intval (X) = Low_Bound then
3535 Error_Msg_FE -- CODEFIX
3536 ("\suggested replacement: `&''First`", X, Ent);
3538 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3539 Error_Msg_FE -- CODEFIX
3540 ("\suggested replacement: `&''First + ^`", X, Ent);
3544 -- Case where original form of subscript is more complex
3547 -- Build string X'First - 1 + expression where the expression
3548 -- is the original subscript. If the expression starts with "1
3549 -- + ", then the "- 1 + 1" is elided.
3551 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3552 Error_Msg_Strlen := 13;
3555 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3556 Tref : constant Source_Buffer_Ptr :=
3557 Source_Text (Get_Source_File_Index (Sref));
3558 -- Tref (Sref) is used to scan the subscript
3561 -- Parentheses counter when scanning subscript
3564 -- Tref (Sref) points to start of subscript
3566 -- Elide - 1 if subscript starts with 1 +
3568 if Tref (Sref .. Sref + 2) = "1 +" then
3569 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3572 elsif Tref (Sref .. Sref + 1) = "1+" then
3573 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3577 -- Now we will copy the subscript to the string buffer
3581 -- Count parens, exit if terminating right paren. Note
3582 -- check to ignore paren appearing as character literal.
3584 if Tref (Sref + 1) = '''
3586 Tref (Sref - 1) = '''
3590 if Tref (Sref) = '(' then
3592 elsif Tref (Sref) = ')' then
3598 -- Done if terminating double dot (slice case)
3601 and then (Tref (Sref .. Sref + 1) = ".."
3603 Tref (Sref .. Sref + 2) = " ..");
3605 -- Quit if we have hit EOF character, something wrong
3607 if Tref (Sref) = EOF then
3611 -- String literals are too much of a pain to handle
3613 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3617 -- If we have a 'Range reference, then this is a case
3618 -- where we cannot easily give a replacement. Don't try!
3620 if Tref (Sref .. Sref + 4) = "range"
3621 and then Tref (Sref - 1) < 'A'
3622 and then Tref (Sref + 5) < 'A'
3627 -- Else store next character
3629 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3630 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3633 -- If we get more than 40 characters then the expression
3634 -- is too long to copy, or something has gone wrong. In
3635 -- either case, just skip the attempt at a suggested fix.
3637 if Error_Msg_Strlen > 40 then
3643 -- Replacement subscript is now in string buffer
3645 Error_Msg_FE -- CODEFIX
3646 ("\suggested replacement: `&~`", Original_Node (X), Ent);
3649 -- Case where subscript is of the form X'Length
3651 elsif Length_Reference (X) then
3653 Error_Msg_Node_2 := Ent;
3655 ("\suggest replacement of `&''Length` by `&''Last`",
3658 -- Case where subscript is of the form X'Length - expression
3660 elsif Nkind (X) = N_Op_Subtract
3661 and then Length_Reference (Left_Opnd (X))
3664 Error_Msg_Node_2 := Ent;
3666 ("\suggest replacement of `&''Length` by `&''Last`",
3667 Left_Opnd (X), Ent);
3669 end Test_Suspicious_Index;
3671 -- Start of processing for Warn_On_Suspicious_Index
3674 -- Only process if warnings activated
3676 if Warn_On_Assumed_Low_Bound then
3678 -- Test if array is simple entity name
3680 if Is_Entity_Name (Name) then
3682 -- Test if array is parameter of unconstrained string type
3684 Ent := Entity (Name);
3688 and then Is_Suspicious_Type (Typ)
3689 and then not Low_Bound_Tested (Ent)
3691 Test_Suspicious_Index;
3695 end Warn_On_Suspicious_Index;
3697 --------------------------------------
3698 -- Warn_On_Unassigned_Out_Parameter --
3699 --------------------------------------
3701 procedure Warn_On_Unassigned_Out_Parameter
3702 (Return_Node : Node_Id;
3703 Scope_Id : Entity_Id)
3709 -- Ignore if procedure or return statement does not come from source
3711 if not Comes_From_Source (Scope_Id)
3712 or else not Comes_From_Source (Return_Node)
3717 -- Loop through formals
3719 Form := First_Formal (Scope_Id);
3720 while Present (Form) loop
3722 -- We are only interested in OUT parameters that come from source
3723 -- and are never set in the source, and furthermore only in scalars
3724 -- since non-scalars generate too many false positives.
3726 if Ekind (Form) = E_Out_Parameter
3727 and then Never_Set_In_Source_Check_Spec (Form)
3728 and then Is_Scalar_Type (Etype (Form))
3729 and then not Present (Unset_Reference (Form))
3731 -- Before we issue the warning, an add ad hoc defence against the
3732 -- most common case of false positives with this warning which is
3733 -- the case where there is a Boolean OUT parameter that has been
3734 -- set, and whose meaning is "ignore the values of the other
3735 -- parameters". We can't of course reliably tell this case at
3736 -- compile time, but the following test kills a lot of false
3737 -- positives, without generating a significant number of false
3738 -- negatives (missed real warnings).
3740 Form2 := First_Formal (Scope_Id);
3741 while Present (Form2) loop
3742 if Ekind (Form2) = E_Out_Parameter
3743 and then Root_Type (Etype (Form2)) = Standard_Boolean
3744 and then not Never_Set_In_Source_Check_Spec (Form2)
3749 Next_Formal (Form2);
3752 -- Here all conditions are met, record possible unset reference
3754 Set_Unset_Reference (Form, Return_Node);
3759 end Warn_On_Unassigned_Out_Parameter;
3761 ---------------------------------
3762 -- Warn_On_Unreferenced_Entity --
3763 ---------------------------------
3765 procedure Warn_On_Unreferenced_Entity
3766 (Spec_E : Entity_Id;
3767 Body_E : Entity_Id := Empty)
3769 E : Entity_Id := Spec_E;
3772 if not Referenced_Check_Spec (E)
3773 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3774 and then not Warnings_Off_Check_Spec (E)
3779 -- Case of variable that is assigned but not read. We suppress
3780 -- the message if the variable is volatile, has an address
3781 -- clause, is aliased, or is a renaming, or is imported.
3783 if Referenced_As_LHS_Check_Spec (E)
3784 and then No (Address_Clause (E))
3785 and then not Is_Volatile (E)
3787 if Warn_On_Modified_Unread
3788 and then not Is_Imported (E)
3789 and then not Is_Return_Object (E)
3790 and then not Is_Aliased (E)
3791 and then No (Renamed_Object (E))
3793 if not Has_Pragma_Unmodified_Check_Spec (E) then
3794 Error_Msg_N -- CODEFIX
3795 ("?variable & is assigned but never read!", E);
3798 Set_Last_Assignment (E, Empty);
3801 -- Normal case of neither assigned nor read (exclude variables
3802 -- referenced as out parameters, since we already generated
3803 -- appropriate warnings at the call point in this case).
3805 elsif not Referenced_As_Out_Parameter (E) then
3807 -- We suppress the message for types for which a valid
3808 -- pragma Unreferenced_Objects has been given, otherwise
3809 -- we go ahead and give the message.
3811 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3813 -- Distinguish renamed case in message
3815 if Present (Renamed_Object (E))
3816 and then Comes_From_Source (Renamed_Object (E))
3819 ("?renamed variable & is not referenced!", E);
3822 ("?variable & is not referenced!", E);
3828 if Present (Renamed_Object (E))
3829 and then Comes_From_Source (Renamed_Object (E))
3832 ("?renamed constant & is not referenced!", E);
3834 Error_Msg_N ("?constant & is not referenced!", E);
3837 when E_In_Parameter |
3838 E_In_Out_Parameter =>
3840 -- Do not emit message for formals of a renaming, because
3841 -- they are never referenced explicitly.
3843 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E))))
3844 /= N_Subprogram_Renaming_Declaration
3846 -- Suppress this message for an IN OUT parameter of a
3847 -- non-scalar type, since it is normal to have only an
3848 -- assignment in such a case.
3850 if Ekind (E) = E_In_Parameter
3851 or else not Referenced_As_LHS_Check_Spec (E)
3852 or else Is_Scalar_Type (E)
3854 if Present (Body_E) then
3858 if not Is_Trivial_Subprogram (Scope (E)) then
3860 ("?formal parameter & is not referenced!",
3866 when E_Out_Parameter =>
3869 when E_Named_Integer |
3871 Error_Msg_N ("?named number & is not referenced!", E);
3873 when E_Enumeration_Literal =>
3874 Error_Msg_N ("?literal & is not referenced!", E);
3877 Error_Msg_N ("?function & is not referenced!", E);
3880 Error_Msg_N ("?procedure & is not referenced!", E);
3882 when E_Generic_Procedure =>
3883 Error_Msg_N -- CODEFIX
3884 ("?generic procedure & is never instantiated!", E);
3886 when E_Generic_Function =>
3887 Error_Msg_N -- CODEFIX
3888 ("?generic function & is never instantiated!", E);
3891 Error_Msg_N ("?type & is not referenced!", E);
3894 Error_Msg_N ("?& is not referenced!", E);
3897 -- Kill warnings on the entity on which the message has been posted
3899 Set_Warnings_Off (E);
3901 end Warn_On_Unreferenced_Entity;
3903 --------------------------------
3904 -- Warn_On_Useless_Assignment --
3905 --------------------------------
3907 procedure Warn_On_Useless_Assignment
3909 N : Node_Id := Empty)
3914 function Check_Ref (N : Node_Id) return Traverse_Result;
3915 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
3916 -- the entity in question is found.
3918 function Test_No_Refs is new Traverse_Func (Check_Ref);
3924 function Check_Ref (N : Node_Id) return Traverse_Result is
3926 -- Check reference to our identifier. We use name equality here
3927 -- because the exception handlers have not yet been analyzed. This
3928 -- is not quite right, but it really does not matter that we fail
3929 -- to output the warning in some obscure cases of name clashes.
3931 if Nkind (N) = N_Identifier
3932 and then Chars (N) = Chars (Ent)
3940 -- Start of processing for Warn_On_Useless_Assignment
3943 -- Check if this is a case we want to warn on, a scalar or access
3944 -- variable with the last assignment field set, with warnings enabled,
3945 -- and which is not imported or exported. We also check that it is OK
3946 -- to capture the value. We are not going to capture any value, but
3947 -- the warning message depends on the same kind of conditions.
3949 if Is_Assignable (Ent)
3950 and then not Is_Return_Object (Ent)
3951 and then Present (Last_Assignment (Ent))
3952 and then not Is_Imported (Ent)
3953 and then not Is_Exported (Ent)
3954 and then Safe_To_Capture_Value (N, Ent)
3955 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
3957 -- Before we issue the message, check covering exception handlers.
3958 -- Search up tree for enclosing statement sequences and handlers.
3960 P := Parent (Last_Assignment (Ent));
3961 while Present (P) loop
3963 -- Something is really wrong if we don't find a handled statement
3964 -- sequence, so just suppress the warning.
3967 Set_Last_Assignment (Ent, Empty);
3970 -- When we hit a package/subprogram body, issue warning and exit
3972 elsif Nkind (P) = N_Subprogram_Body
3973 or else Nkind (P) = N_Package_Body
3975 -- Case of assigned value never referenced
3979 -- Don't give this for OUT and IN OUT formals, since
3980 -- clearly caller may reference the assigned value. Also
3981 -- never give such warnings for internal variables.
3983 if Ekind (Ent) = E_Variable
3984 and then not Is_Internal_Name (Chars (Ent))
3986 if Referenced_As_Out_Parameter (Ent) then
3988 ("?& modified by call, but value never referenced",
3989 Last_Assignment (Ent), Ent);
3992 ("?useless assignment to&, value never referenced!",
3993 Last_Assignment (Ent), Ent);
3997 -- Case of assigned value overwritten
4000 Error_Msg_Sloc := Sloc (N);
4002 if Referenced_As_Out_Parameter (Ent) then
4004 ("?& modified by call, but value overwritten #!",
4005 Last_Assignment (Ent), Ent);
4008 ("?useless assignment to&, value overwritten #!",
4009 Last_Assignment (Ent), Ent);
4013 -- Clear last assignment indication and we are done
4015 Set_Last_Assignment (Ent, Empty);
4018 -- Enclosing handled sequence of statements
4020 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4022 -- Check exception handlers present
4024 if Present (Exception_Handlers (P)) then
4026 -- If we are not at the top level, we regard an inner
4027 -- exception handler as a decisive indicator that we should
4028 -- not generate the warning, since the variable in question
4029 -- may be accessed after an exception in the outer block.
4031 if Nkind (Parent (P)) /= N_Subprogram_Body
4032 and then Nkind (Parent (P)) /= N_Package_Body
4034 Set_Last_Assignment (Ent, Empty);
4037 -- Otherwise we are at the outer level. An exception
4038 -- handler is significant only if it references the
4039 -- variable in question, or if the entity in question
4040 -- is an OUT or IN OUT parameter, which which case
4041 -- the caller can reference it after the exception
4042 -- hanlder completes
4045 if Is_Formal (Ent) then
4046 Set_Last_Assignment (Ent, Empty);
4050 X := First (Exception_Handlers (P));
4051 while Present (X) loop
4052 if Test_No_Refs (X) = Abandon then
4053 Set_Last_Assignment (Ent, Empty);
4067 end Warn_On_Useless_Assignment;
4069 ---------------------------------
4070 -- Warn_On_Useless_Assignments --
4071 ---------------------------------
4073 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4076 if Warn_On_Modified_Unread
4077 and then In_Extended_Main_Source_Unit (E)
4079 Ent := First_Entity (E);
4080 while Present (Ent) loop
4081 Warn_On_Useless_Assignment (Ent);
4085 end Warn_On_Useless_Assignments;
4087 -----------------------------
4088 -- Warnings_Off_Check_Spec --
4089 -----------------------------
4091 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4093 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4095 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4096 -- to mess with flags on both entities.
4098 return Has_Warnings_Off (E)
4100 Has_Warnings_Off (Spec_Entity (E));
4103 return Has_Warnings_Off (E);
4105 end Warnings_Off_Check_Spec;