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 Par_SCO; use Par_SCO;
37 with Rtsfind; use Rtsfind;
39 with Sem_Ch8; use Sem_Ch8;
40 with Sem_Aux; use Sem_Aux;
41 with Sem_Eval; use Sem_Eval;
42 with Sem_Util; use Sem_Util;
43 with Sinfo; use Sinfo;
44 with Sinput; use Sinput;
45 with Snames; use Snames;
46 with Stand; use Stand;
47 with Stringt; use Stringt;
48 with Uintp; use Uintp;
50 package body Sem_Warn is
52 -- The following table collects Id's of entities that are potentially
53 -- unreferenced. See Check_Unset_Reference for further details.
54 -- ??? Check_Unset_Reference has zero information about this table.
56 package Unreferenced_Entities is new Table.Table (
57 Table_Component_Type => Entity_Id,
58 Table_Index_Type => Nat,
60 Table_Initial => Alloc.Unreferenced_Entities_Initial,
61 Table_Increment => Alloc.Unreferenced_Entities_Increment,
62 Table_Name => "Unreferenced_Entities");
64 -- The following table collects potential warnings for IN OUT parameters
65 -- that are referenced but not modified. These warnings are processed when
66 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
67 -- The reason that we defer output of these messages is that we want to
68 -- detect the case where the relevant procedure is used as a generic actual
69 -- in an instantiation, since we suppress the warnings in this case. The
70 -- flag Used_As_Generic_Actual will be set in this case, but only at the
71 -- point of usage. Similarly, we suppress the message if the address of the
72 -- procedure is taken, where the flag Address_Taken may be set later.
74 package In_Out_Warnings is new Table.Table (
75 Table_Component_Type => Entity_Id,
76 Table_Index_Type => Nat,
78 Table_Initial => Alloc.In_Out_Warnings_Initial,
79 Table_Increment => Alloc.In_Out_Warnings_Increment,
80 Table_Name => "In_Out_Warnings");
82 --------------------------------------------------------
83 -- Handling of Warnings Off, Unmodified, Unreferenced --
84 --------------------------------------------------------
86 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
87 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
88 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
90 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
91 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
92 -- must follow some important rules.
94 -- Call these functions as late as possible, after completing all other
95 -- tests, just before the warnings is given. For example, don't write:
97 -- if not Has_Warnings_Off (E)
98 -- and then some-other-predicate-on-E then ..
100 -- Instead the following is preferred
102 -- if some-other-predicate-on-E
103 -- and then Has_Warnings_Off (E)
105 -- This way if some-other-predicate is false, we avoid a false indication
106 -- that a Warnings (Off,E) pragma was useful in preventing a warning.
108 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
109 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
110 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
111 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
112 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
113 -- and so a subsequent test is not needed anyway (though it is harmless).
115 -----------------------
116 -- Local Subprograms --
117 -----------------------
119 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean;
120 -- This returns true if the entity E is declared within a generic package.
121 -- The point of this is to detect variables which are not assigned within
122 -- the generic, but might be assigned outside the package for any given
123 -- instance. These are cases where we leave the warnings to be posted for
124 -- the instance, when we will know more.
126 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id;
127 -- If E is a parameter entity for a subprogram body, then this function
128 -- returns the corresponding spec entity, if not, E is returned unchanged.
130 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean;
131 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
132 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
133 -- a body formal, the setting of the flag in the corresponding spec is
134 -- also checked (and True returned if either flag is True).
136 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean;
137 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
138 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
139 -- a body formal, the setting of the flag in the corresponding spec is
140 -- also checked (and True returned if either flag is True).
142 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean;
143 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
144 -- this is simply the setting of the flag Never_Set_In_Source. If E is
145 -- a body formal, the setting of the flag in the corresponding spec is
146 -- also checked (and False returned if either flag is False).
148 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
149 -- This function traverses the expression tree represented by the node N
150 -- and determines if any sub-operand is a reference to an entity for which
151 -- the Warnings_Off flag is set. True is returned if such an entity is
152 -- encountered, and False otherwise.
154 function Referenced_Check_Spec (E : Entity_Id) return Boolean;
155 -- Tests Referenced status for entity E. If E is not a formal, this is
156 -- simply the setting of the flag Referenced. If E is a body formal, the
157 -- setting of the flag in the corresponding spec is also checked (and True
158 -- returned if either flag is True).
160 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean;
161 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
162 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
163 -- formal, the setting of the flag in the corresponding spec is also
164 -- checked (and True returned if either flag is True).
166 function Referenced_As_Out_Parameter_Check_Spec
167 (E : Entity_Id) return Boolean;
168 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
169 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
170 -- is a body formal, the setting of the flag in the corresponding spec is
171 -- also checked (and True returned if either flag is True).
173 procedure Warn_On_Unreferenced_Entity
175 Body_E : Entity_Id := Empty);
176 -- Output warnings for unreferenced entity E. For the case of an entry
177 -- formal, Body_E is the corresponding body entity for a particular
178 -- accept statement, and the message is posted on Body_E. In all other
179 -- cases, Body_E is ignored and must be Empty.
181 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean;
182 -- Returns True if Warnings_Off is set for the entity E or (in the case
183 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
185 --------------------------
186 -- Check_Code_Statement --
187 --------------------------
189 procedure Check_Code_Statement (N : Node_Id) is
191 -- If volatile, nothing to worry about
193 if Is_Asm_Volatile (N) then
197 -- Warn if no input or no output
199 Setup_Asm_Inputs (N);
201 if No (Asm_Input_Value) then
203 ("?code statement with no inputs should usually be Volatile!", N);
207 Setup_Asm_Outputs (N);
209 if No (Asm_Output_Variable) then
211 ("?code statement with no outputs should usually be Volatile!", N);
215 -- Check multiple code statements in a row
217 if Is_List_Member (N)
218 and then Present (Prev (N))
219 and then Nkind (Prev (N)) = N_Code_Statement
222 ("?code statements in sequence should usually be Volatile!", N);
224 ("\?(suggest using template with multiple instructions)!", N);
226 end Check_Code_Statement;
228 ---------------------------------
229 -- Check_Infinite_Loop_Warning --
230 ---------------------------------
232 -- The case we look for is a while loop which tests a local variable, where
233 -- there is no obvious direct or possible indirect update of the variable
234 -- within the body of the loop.
236 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
237 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
239 Ref : Node_Id := Empty;
240 -- Reference in iteration scheme to variable that might not be modified
241 -- in loop, indicating a possible infinite loop.
243 Var : Entity_Id := Empty;
244 -- Corresponding entity (entity of Ref)
246 Function_Call_Found : Boolean := False;
247 -- True if Find_Var found a function call in the condition
249 procedure Find_Var (N : Node_Id);
250 -- Inspect condition to see if it depends on a single entity reference.
251 -- If so, Ref is set to point to the reference node, and Var is set to
252 -- the referenced Entity.
254 function Has_Indirection (T : Entity_Id) return Boolean;
255 -- If the controlling variable is an access type, or is a record type
256 -- with access components, assume that it is changed indirectly and
257 -- suppress the warning. As a concession to low-level programming, in
258 -- particular within Declib, we also suppress warnings on a record
259 -- type that contains components of type Address or Short_Address.
261 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
262 -- Given an entity name, see if the name appears to have something to
263 -- do with I/O or network stuff, and if so, return True. Used to kill
264 -- some false positives on a heuristic basis that such functions will
265 -- likely have some strange side effect dependencies. A rather funny
266 -- kludge, but warning messages are in the heuristics business.
268 function Test_Ref (N : Node_Id) return Traverse_Result;
269 -- Test for reference to variable in question. Returns Abandon if
270 -- matching reference found.
272 function Find_Ref is new Traverse_Func (Test_Ref);
273 -- Function to traverse body of procedure. Returns Abandon if matching
280 procedure Find_Var (N : Node_Id) is
282 -- Condition is a direct variable reference
284 if Is_Entity_Name (N) then
288 -- Case of condition is a comparison with compile time known value
290 elsif Nkind (N) in N_Op_Compare then
291 if Compile_Time_Known_Value (Right_Opnd (N)) then
292 Find_Var (Left_Opnd (N));
294 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
295 Find_Var (Right_Opnd (N));
297 -- Ignore any other comparison
303 -- If condition is a negation, check its operand
305 elsif Nkind (N) = N_Op_Not then
306 Find_Var (Right_Opnd (N));
308 -- Case of condition is function call
310 elsif Nkind (N) = N_Function_Call then
312 Function_Call_Found := True;
314 -- Forget it if function name is not entity, who knows what
315 -- we might be calling?
317 if not Is_Entity_Name (Name (N)) then
320 -- Forget it if function name is suspicious. A strange test
321 -- but warning generation is in the heuristics business!
323 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
326 -- Forget it if warnings are suppressed on function entity
328 elsif Has_Warnings_Off (Entity (Name (N))) then
332 -- OK, see if we have one argument
335 PA : constant List_Id := Parameter_Associations (N);
338 -- One argument, so check the argument
341 and then List_Length (PA) = 1
343 if Nkind (First (PA)) = N_Parameter_Association then
344 Find_Var (Explicit_Actual_Parameter (First (PA)));
346 Find_Var (First (PA));
356 -- Any other kind of node is not something we warn for
363 ---------------------
364 -- Has_Indirection --
365 ---------------------
367 function Has_Indirection (T : Entity_Id) return Boolean is
372 if Is_Access_Type (T) then
375 elsif Is_Private_Type (T)
376 and then Present (Full_View (T))
377 and then Is_Access_Type (Full_View (T))
381 elsif Is_Record_Type (T) then
384 elsif Is_Private_Type (T)
385 and then Present (Full_View (T))
386 and then Is_Record_Type (Full_View (T))
388 Rec := Full_View (T);
393 Comp := First_Component (Rec);
394 while Present (Comp) loop
395 if Is_Access_Type (Etype (Comp))
396 or else Is_Descendent_Of_Address (Etype (Comp))
401 Next_Component (Comp);
407 ---------------------------------
408 -- Is_Suspicious_Function_Name --
409 ---------------------------------
411 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
414 function Substring_Present (S : String) return Boolean;
415 -- Returns True if name buffer has given string delimited by non-
416 -- alphabetic characters or by end of string. S is lower case.
418 -----------------------
419 -- Substring_Present --
420 -----------------------
422 function Substring_Present (S : String) return Boolean is
423 Len : constant Natural := S'Length;
426 for J in 1 .. Name_Len - (Len - 1) loop
427 if Name_Buffer (J .. J + (Len - 1)) = S
430 or else Name_Buffer (J - 1) not in 'a' .. 'z')
433 or else Name_Buffer (J + Len) not in 'a' .. 'z')
440 end Substring_Present;
442 -- Start of processing for Is_Suspicious_Function_Name
446 while Present (S) and then S /= Standard_Standard loop
447 Get_Name_String (Chars (S));
449 if Substring_Present ("io")
450 or else Substring_Present ("file")
451 or else Substring_Present ("network")
460 end Is_Suspicious_Function_Name;
466 function Test_Ref (N : Node_Id) return Traverse_Result is
468 -- Waste of time to look at iteration scheme
473 -- Direct reference to variable in question
475 elsif Is_Entity_Name (N)
476 and then Present (Entity (N))
477 and then Entity (N) = Var
479 -- If this is an lvalue, then definitely abandon, since
480 -- this could be a direct modification of the variable.
482 if May_Be_Lvalue (N) then
486 -- If we appear in the context of a procedure call, then also
487 -- abandon, since there may be issues of non-visible side
488 -- effects going on in the call.
497 exit when P = Loop_Statement;
499 -- Abandon if at procedure call, or something strange is
500 -- going on (perhaps a node with no parent that should
501 -- have one but does not?) As always, for a warning we
502 -- prefer to just abandon the warning than get into the
503 -- business of complaining about the tree structure here!
505 if No (P) or else Nkind (P) = N_Procedure_Call_Statement then
511 -- Reference to variable renaming variable in question
513 elsif Is_Entity_Name (N)
514 and then Present (Entity (N))
515 and then Ekind (Entity (N)) = E_Variable
516 and then Present (Renamed_Object (Entity (N)))
517 and then Is_Entity_Name (Renamed_Object (Entity (N)))
518 and then Entity (Renamed_Object (Entity (N))) = Var
519 and then May_Be_Lvalue (N)
523 -- Call to subprogram
525 elsif Nkind (N) = N_Procedure_Call_Statement
526 or else Nkind (N) = N_Function_Call
528 -- If subprogram is within the scope of the entity we are dealing
529 -- with as the loop variable, then it could modify this parameter,
530 -- so we abandon in this case. In the case of a subprogram that is
531 -- not an entity we also abandon. The check for no entity being
532 -- present is a defense against previous errors.
534 if not Is_Entity_Name (Name (N))
535 or else No (Entity (Name (N)))
536 or else Scope_Within (Entity (Name (N)), Scope (Var))
542 -- All OK, continue scan
547 -- Start of processing for Check_Infinite_Loop_Warning
550 -- We need a while iteration with no condition actions. Condition
551 -- actions just make things too complicated to get the warning right.
554 or else No (Condition (Iter))
555 or else Present (Condition_Actions (Iter))
556 or else Debug_Flag_Dot_W
561 -- Initial conditions met, see if condition is of right form
563 Find_Var (Condition (Iter));
565 -- Nothing to do if local variable from source not found. If it's a
566 -- renaming, it is probably renaming something too complicated to deal
570 or else Ekind (Var) /= E_Variable
571 or else Is_Library_Level_Entity (Var)
572 or else not Comes_From_Source (Var)
573 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
577 -- Nothing to do if there is some indirection involved (assume that the
578 -- designated variable might be modified in some way we don't see).
579 -- However, if no function call was found, then we don't care about
580 -- indirections, because the condition must be something like "while X
581 -- /= null loop", so we don't care if X.all is modified in the loop.
583 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
586 -- Same sort of thing for volatile variable, might be modified by
587 -- some other task or by the operating system in some way.
589 elsif Is_Volatile (Var) then
593 -- Filter out case of original statement sequence starting with delay.
594 -- We assume this is a multi-tasking program and that the condition
595 -- is affected by other threads (some kind of busy wait).
598 Fstm : constant Node_Id :=
599 Original_Node (First (Statements (Loop_Statement)));
601 if Nkind (Fstm) = N_Delay_Relative_Statement
602 or else Nkind (Fstm) = N_Delay_Until_Statement
608 -- We have a variable reference of the right form, now we scan the loop
609 -- body to see if it looks like it might not be modified
611 if Find_Ref (Loop_Statement) = OK then
613 ("?variable& is not modified in loop body!", Ref, Var);
615 ("\?possible infinite loop!", Ref);
617 end Check_Infinite_Loop_Warning;
619 ----------------------------
620 -- Check_Low_Bound_Tested --
621 ----------------------------
623 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
625 if Comes_From_Source (Expr) then
627 L : constant Node_Id := Left_Opnd (Expr);
628 R : constant Node_Id := Right_Opnd (Expr);
630 if Nkind (L) = N_Attribute_Reference
631 and then Attribute_Name (L) = Name_First
632 and then Is_Entity_Name (Prefix (L))
633 and then Is_Formal (Entity (Prefix (L)))
635 Set_Low_Bound_Tested (Entity (Prefix (L)));
638 if Nkind (R) = N_Attribute_Reference
639 and then Attribute_Name (R) = Name_First
640 and then Is_Entity_Name (Prefix (R))
641 and then Is_Formal (Entity (Prefix (R)))
643 Set_Low_Bound_Tested (Entity (Prefix (R)));
647 end Check_Low_Bound_Tested;
649 ----------------------
650 -- Check_References --
651 ----------------------
653 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
660 Accept_Statement : Node_Id) return Entity_Id;
661 -- For an entry formal entity from an entry declaration, find the
662 -- corresponding body formal from the given accept statement.
664 function Missing_Subunits return Boolean;
665 -- We suppress warnings when there are missing subunits, because this
666 -- may generate too many false positives: entities in a parent may only
667 -- be referenced in one of the subunits. We make an exception for
668 -- subunits that contain no other stubs.
670 procedure Output_Reference_Error (M : String);
671 -- Used to output an error message. Deals with posting the error on the
672 -- body formal in the accept case.
674 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
675 -- This is true if the entity in question is potentially referenceable
676 -- from another unit. This is true for entities in packages that are at
677 -- the library level.
679 function Warnings_Off_E1 return Boolean;
680 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
681 -- or for the base type of E1T.
689 Accept_Statement : Node_Id) return Entity_Id
691 Body_Param : Node_Id;
695 -- Loop to find matching parameter in accept statement
697 Body_Param := First (Parameter_Specifications (Accept_Statement));
698 while Present (Body_Param) loop
699 Body_E := Defining_Identifier (Body_Param);
701 if Chars (Body_E) = Chars (E) then
708 -- Should never fall through, should always find a match
713 ----------------------
714 -- Missing_Subunits --
715 ----------------------
717 function Missing_Subunits return Boolean is
721 if not Unloaded_Subunits then
723 -- Normal compilation, all subunits are present
727 elsif E /= Main_Unit_Entity then
729 -- No warnings on a stub that is not the main unit
733 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
734 D := First (Declarations (Unit_Declaration_Node (E)));
735 while Present (D) loop
737 -- No warnings if the proper body contains nested stubs
739 if Nkind (D) in N_Body_Stub then
749 -- Missing stubs elsewhere
753 end Missing_Subunits;
755 ----------------------------
756 -- Output_Reference_Error --
757 ----------------------------
759 procedure Output_Reference_Error (M : String) is
761 -- Never issue messages for internal names
763 if Is_Internal_Name (Chars (E1)) then
767 -- Don't output message for IN OUT formal unless we have the warning
768 -- flag specifically set. It is a bit odd to distinguish IN OUT
769 -- formals from other cases. This distinction is historical in
770 -- nature. Warnings for IN OUT formals were added fairly late.
772 if Ekind (E1) = E_In_Out_Parameter
773 and then not Check_Unreferenced_Formals
778 -- Other than accept case, post error on defining identifier
783 -- Accept case, find body formal to post the message
786 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
789 end Output_Reference_Error;
791 ----------------------------
792 -- Publicly_Referenceable --
793 ----------------------------
795 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
800 -- A formal parameter is never referenceable outside the body of its
801 -- subprogram or entry.
803 if Is_Formal (Ent) then
807 -- Examine parents to look for a library level package spec. But if
808 -- we find a body or block or other similar construct along the way,
809 -- we cannot be referenced.
816 -- If we get to top of tree, then publicly referenceable
821 -- If we reach a generic package declaration, then always
822 -- consider this referenceable, since any instantiation will
823 -- have access to the entities in the generic package. Note
824 -- that the package itself may not be instantiated, but then
825 -- we will get a warning for the package entity.
827 -- Note that generic formal parameters are themselves not
828 -- publicly referenceable in an instance, and warnings on them
831 when N_Generic_Package_Declaration =>
833 not Is_List_Member (Prev)
834 or else List_Containing (Prev)
835 /= Generic_Formal_Declarations (P);
837 -- Similarly, the generic formals of a generic subprogram are
840 when N_Generic_Subprogram_Declaration =>
841 if Is_List_Member (Prev)
842 and then List_Containing (Prev) =
843 Generic_Formal_Declarations (P)
850 -- If we reach a subprogram body, entity is not referenceable
851 -- unless it is the defining entity of the body. This will
852 -- happen, e.g. when a function is an attribute renaming that
853 -- is rewritten as a body.
855 when N_Subprogram_Body =>
856 if Ent /= Defining_Entity (P) then
862 -- If we reach any other body, definitely not referenceable
864 when N_Package_Body |
872 -- For all other cases, keep looking up tree
879 end Publicly_Referenceable;
881 ---------------------
882 -- Warnings_Off_E1 --
883 ---------------------
885 function Warnings_Off_E1 return Boolean is
887 return Has_Warnings_Off (E1T)
888 or else Has_Warnings_Off (Base_Type (E1T))
889 or else Warnings_Off_Check_Spec (E1);
892 -- Start of processing for Check_References
895 -- No messages if warnings are suppressed, or if we have detected any
896 -- real errors so far (this last check avoids junk messages resulting
897 -- from errors, e.g. a subunit that is not loaded).
899 if Warning_Mode = Suppress
900 or else Serious_Errors_Detected /= 0
905 -- We also skip the messages if any subunits were not loaded (see
906 -- comment in Sem_Ch10 to understand how this is set, and why it is
907 -- necessary to suppress the warnings in this case).
909 if Missing_Subunits then
913 -- Otherwise loop through entities, looking for suspicious stuff
915 E1 := First_Entity (E);
916 while Present (E1) loop
919 -- We are only interested in source entities. We also don't issue
920 -- warnings within instances, since the proper place for such
921 -- warnings is on the template when it is compiled.
923 if Comes_From_Source (E1)
924 and then Instantiation_Location (Sloc (E1)) = No_Location
926 -- We are interested in variables and out/in-out parameters, but
927 -- we exclude protected types, too complicated to worry about.
929 if Ekind (E1) = E_Variable
931 ((Ekind (E1) = E_Out_Parameter
932 or else Ekind (E1) = E_In_Out_Parameter)
933 and then not Is_Protected_Type (Current_Scope))
935 -- Case of an unassigned variable
937 -- First gather any Unset_Reference indication for E1. In the
938 -- case of a parameter, it is the Spec_Entity that is relevant.
940 if Ekind (E1) = E_Out_Parameter
941 and then Present (Spec_Entity (E1))
943 UR := Unset_Reference (Spec_Entity (E1));
945 UR := Unset_Reference (E1);
948 -- Special processing for access types
951 and then Is_Access_Type (E1T)
953 -- For access types, the only time we made a UR entry was
954 -- for a dereference, and so we post the appropriate warning
955 -- here (note that the dereference may not be explicit in
956 -- the source, for example in the case of a dispatching call
957 -- with an anonymous access controlling formal, or of an
958 -- assignment of a pointer involving discriminant check on
959 -- the designated object).
961 if not Warnings_Off_E1 then
962 Error_Msg_NE ("?& may be null!", UR, E1);
967 -- Case of variable that could be a constant. Note that we
968 -- never signal such messages for generic package entities,
969 -- since a given instance could have modifications outside
972 elsif Warn_On_Constant
973 and then (Ekind (E1) = E_Variable
974 and then Has_Initial_Value (E1))
975 and then Never_Set_In_Source_Check_Spec (E1)
976 and then not Address_Taken (E1)
977 and then not Generic_Package_Spec_Entity (E1)
979 -- A special case, if this variable is volatile and not
980 -- imported, it is not helpful to tell the programmer
981 -- to mark the variable as constant, since this would be
982 -- illegal by virtue of RM C.6(13).
984 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
985 and then not Is_Imported (E1)
988 ("?& is not modified, volatile has no effect!", E1);
990 -- Another special case, Exception_Occurrence, this catches
991 -- the case of exception choice (and a bit more too, but not
992 -- worth doing more investigation here).
994 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
997 -- Here we give the warning if referenced and no pragma
998 -- Unreferenced or Unmodified is present.
1003 if Ekind (E1) = E_Variable then
1004 if Referenced_Check_Spec (E1)
1005 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1006 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1008 if not Warnings_Off_E1 then
1009 Error_Msg_N -- CODEFIX
1010 ("?& is not modified, "
1011 & "could be declared constant!",
1018 -- Other cases of a variable or parameter never set in source
1020 elsif Never_Set_In_Source_Check_Spec (E1)
1022 -- No warning if warning for this case turned off
1024 and then Warn_On_No_Value_Assigned
1026 -- No warning if address taken somewhere
1028 and then not Address_Taken (E1)
1030 -- No warning if explicit initial value
1032 and then not Has_Initial_Value (E1)
1034 -- No warning for generic package spec entities, since we
1035 -- might set them in a child unit or something like that
1037 and then not Generic_Package_Spec_Entity (E1)
1039 -- No warning if fully initialized type, except that for
1040 -- this purpose we do not consider access types to qualify
1041 -- as fully initialized types (relying on an access type
1042 -- variable being null when it is never set is a bit odd!)
1044 -- Also we generate warning for an out parameter that is
1045 -- never referenced, since again it seems odd to rely on
1046 -- default initialization to set an out parameter value.
1048 and then (Is_Access_Type (E1T)
1049 or else Ekind (E1) = E_Out_Parameter
1050 or else not Is_Fully_Initialized_Type (E1T))
1052 -- Do not output complaint about never being assigned a
1053 -- value if a pragma Unmodified applies to the variable
1054 -- we are examining, or if it is a parameter, if there is
1055 -- a pragma Unreferenced for the corresponding spec, or
1056 -- if the type is marked as having unreferenced objects.
1057 -- The last is a little peculiar, but better too few than
1058 -- too many warnings in this situation.
1060 if Has_Pragma_Unreferenced_Objects (E1T)
1061 or else Has_Pragma_Unmodified_Check_Spec (E1)
1065 -- IN OUT parameter case where parameter is referenced. We
1066 -- separate this out, since this is the case where we delay
1067 -- output of the warning until more information is available
1068 -- (about use in an instantiation or address being taken).
1070 elsif Ekind (E1) = E_In_Out_Parameter
1071 and then Referenced_Check_Spec (E1)
1073 -- Suppress warning if private type, and the procedure
1074 -- has a separate declaration in a different unit. This
1075 -- is the case where the client of a package sees only
1076 -- the private type, and it may be quite reasonable
1077 -- for the logical view to be IN OUT, even if the
1078 -- implementation ends up using access types or some
1079 -- other method to achieve the local effect of a
1080 -- modification. On the other hand if the spec and body
1081 -- are in the same unit, we are in the package body and
1082 -- there we have less excuse for a junk IN OUT parameter.
1084 if Has_Private_Declaration (E1T)
1085 and then Present (Spec_Entity (E1))
1086 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1090 -- Suppress warning for any parameter of a dispatching
1091 -- operation, since it is quite reasonable to have an
1092 -- operation that is overridden, and for some subclasses
1093 -- needs the formal to be IN OUT and for others happens
1094 -- not to assign it.
1096 elsif Is_Dispatching_Operation
1097 (Scope (Goto_Spec_Entity (E1)))
1101 -- Suppress warning if composite type contains any access
1102 -- component, since the logical effect of modifying a
1103 -- parameter may be achieved by modifying a referenced
1106 elsif Is_Composite_Type (E1T)
1107 and then Has_Access_Values (E1T)
1111 -- Suppress warning on formals of an entry body. All
1112 -- references are attached to the formal in the entry
1113 -- declaration, which are marked Is_Entry_Formal.
1115 elsif Ekind (Scope (E1)) = E_Entry
1116 and then not Is_Entry_Formal (E1)
1120 -- OK, looks like warning for an IN OUT parameter that
1121 -- could be IN makes sense, but we delay the output of
1122 -- the warning, pending possibly finding out later on
1123 -- that the associated subprogram is used as a generic
1124 -- actual, or its address/access is taken. In these two
1125 -- cases, we suppress the warning because the context may
1126 -- force use of IN OUT, even if in this particular case
1127 -- the formal is not modified.
1130 In_Out_Warnings.Append (E1);
1133 -- Other cases of formals
1135 elsif Is_Formal (E1) then
1136 if not Is_Trivial_Subprogram (Scope (E1)) then
1137 if Referenced_Check_Spec (E1) then
1138 if not Has_Pragma_Unmodified_Check_Spec (E1)
1139 and then not Warnings_Off_E1
1141 Output_Reference_Error
1142 ("?formal parameter& is read but "
1143 & "never assigned!");
1146 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1147 and then not Warnings_Off_E1
1149 Output_Reference_Error
1150 ("?formal parameter& is not referenced!");
1157 if Referenced (E1) then
1158 if not Has_Unmodified (E1)
1159 and then not Warnings_Off_E1
1161 Output_Reference_Error
1162 ("?variable& is read but never assigned!");
1165 elsif not Has_Unreferenced (E1)
1166 and then not Warnings_Off_E1
1168 Output_Reference_Error -- CODEFIX
1169 ("?variable& is never read and never assigned!");
1172 -- Deal with special case where this variable is hidden
1173 -- by a loop variable.
1175 if Ekind (E1) = E_Variable
1176 and then Present (Hiding_Loop_Variable (E1))
1177 and then not Warnings_Off_E1
1180 ("?for loop implicitly declares loop variable!",
1181 Hiding_Loop_Variable (E1));
1183 Error_Msg_Sloc := Sloc (E1);
1185 ("\?declaration hides & declared#!",
1186 Hiding_Loop_Variable (E1));
1193 -- Check for unset reference
1195 if Warn_On_No_Value_Assigned and then Present (UR) then
1197 -- For other than access type, go back to original node to
1198 -- deal with case where original unset reference has been
1199 -- rewritten during expansion.
1201 -- In some cases, the original node may be a type conversion
1202 -- or qualification, and in this case we want the object
1205 UR := Original_Node (UR);
1206 while Nkind (UR) = N_Type_Conversion
1207 or else Nkind (UR) = N_Qualified_Expression
1209 UR := Expression (UR);
1212 -- Here we issue the warning, all checks completed
1214 -- If we have a return statement, this was a case of an OUT
1215 -- parameter not being set at the time of the return. (Note:
1216 -- it can't be N_Extended_Return_Statement, because those
1217 -- are only for functions, and functions do not allow OUT
1220 if not Is_Trivial_Subprogram (Scope (E1)) then
1221 if Nkind (UR) = N_Simple_Return_Statement
1222 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1224 if not Warnings_Off_E1 then
1226 ("?OUT parameter& not set before return", UR, E1);
1229 -- If the unset reference is a selected component
1230 -- prefix from source, mention the component as well.
1231 -- If the selected component comes from expansion, all
1232 -- we know is that the entity is not fully initialized
1233 -- at the point of the reference. Locate a random
1234 -- uninitialized component to get a better message.
1236 elsif Nkind (Parent (UR)) = N_Selected_Component then
1237 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1239 if not Comes_From_Source (Parent (UR)) then
1244 Comp := First_Entity (E1T);
1245 while Present (Comp) loop
1246 if Ekind (Comp) = E_Component
1247 and then Nkind (Parent (Comp)) =
1248 N_Component_Declaration
1249 and then No (Expression (Parent (Comp)))
1251 Error_Msg_Node_2 := Comp;
1260 -- Issue proper warning. This is a case of referencing
1261 -- a variable before it has been explicitly assigned.
1262 -- For access types, UR was only set for dereferences,
1263 -- so the issue is that the value may be null.
1265 if not Is_Trivial_Subprogram (Scope (E1)) then
1266 if not Warnings_Off_E1 then
1267 if Is_Access_Type (Etype (Parent (UR))) then
1268 Error_Msg_N ("?`&.&` may be null!", UR);
1271 ("?`&.&` may be referenced before "
1272 & "it has a value!", UR);
1277 -- All other cases of unset reference active
1279 elsif not Warnings_Off_E1 then
1281 ("?& may be referenced before it has a value!",
1290 -- Then check for unreferenced entities. Note that we are only
1291 -- interested in entities whose Referenced flag is not set.
1293 if not Referenced_Check_Spec (E1)
1295 -- If Referenced_As_LHS is set, then that's still interesting
1296 -- (potential "assigned but never read" case), but not if we
1297 -- have pragma Unreferenced, which cancels this warning.
1299 and then (not Referenced_As_LHS_Check_Spec (E1)
1300 or else not Has_Unreferenced (E1))
1302 -- Check that warnings on unreferenced entities are enabled
1305 ((Check_Unreferenced and then not Is_Formal (E1))
1307 -- Case of warning on unreferenced formal
1310 (Check_Unreferenced_Formals and then Is_Formal (E1))
1312 -- Case of warning on unread variables modified by an
1313 -- assignment, or an OUT parameter if it is the only one.
1316 (Warn_On_Modified_Unread
1317 and then Referenced_As_LHS_Check_Spec (E1))
1319 -- Case of warning on any unread OUT parameter (note
1320 -- such indications are only set if the appropriate
1321 -- warning options were set, so no need to recheck here.
1324 Referenced_As_Out_Parameter_Check_Spec (E1))
1326 -- Labels, and enumeration literals, and exceptions. The
1327 -- warnings are also placed on local packages that cannot be
1328 -- referenced from elsewhere, including those declared within a
1331 and then (Is_Object (E1)
1335 Ekind (E1) = E_Label
1337 Ekind (E1) = E_Exception
1339 Ekind (E1) = E_Named_Integer
1341 Ekind (E1) = E_Named_Real
1343 Is_Overloadable (E1)
1345 -- Package case, if the main unit is a package spec
1346 -- or generic package spec, then there may be a
1347 -- corresponding body that references this package
1348 -- in some other file. Otherwise we can be sure
1349 -- that there is no other reference.
1352 (Ekind (E1) = E_Package
1354 not Is_Package_Or_Generic_Package
1355 (Cunit_Entity (Current_Sem_Unit))))
1357 -- Exclude instantiations, since there is no reason why every
1358 -- entity in an instantiation should be referenced.
1360 and then Instantiation_Location (Sloc (E1)) = No_Location
1362 -- Exclude formal parameters from bodies if the corresponding
1363 -- spec entity has been referenced in the case where there is
1366 and then not (Is_Formal (E1)
1368 Ekind (Scope (E1)) = E_Subprogram_Body
1370 Present (Spec_Entity (E1))
1372 Referenced (Spec_Entity (E1)))
1374 -- Consider private type referenced if full view is referenced.
1375 -- If there is not full view, this is a generic type on which
1376 -- warnings are also useful.
1379 not (Is_Private_Type (E1)
1381 Present (Full_View (E1))
1382 and then Referenced (Full_View (E1)))
1384 -- Don't worry about full view, only about private type
1386 and then not Has_Private_Declaration (E1)
1388 -- Eliminate dispatching operations from consideration, we
1389 -- cannot tell if these are referenced or not in any easy
1390 -- manner (note this also catches Adjust/Finalize/Initialize).
1392 and then not Is_Dispatching_Operation (E1)
1394 -- Check entity that can be publicly referenced (we do not give
1395 -- messages for such entities, since there could be other
1396 -- units, not involved in this compilation, that contain
1397 -- relevant references.
1399 and then not Publicly_Referenceable (E1)
1401 -- Class wide types are marked as source entities, but they are
1402 -- not really source entities, and are always created, so we do
1403 -- not care if they are not referenced.
1405 and then Ekind (E1) /= E_Class_Wide_Type
1407 -- Objects other than parameters of task types are allowed to
1408 -- be non-referenced, since they start up tasks!
1410 and then ((Ekind (E1) /= E_Variable
1411 and then Ekind (E1) /= E_Constant
1412 and then Ekind (E1) /= E_Component)
1413 or else not Is_Task_Type (E1T))
1415 -- For subunits, only place warnings on the main unit itself,
1416 -- since parent units are not completely compiled.
1418 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1420 Get_Source_Unit (E1) = Main_Unit)
1422 -- No warning on a return object, because these are often
1423 -- created with a single expression and an implicit return.
1424 -- If the object is a variable there will be a warning
1425 -- indicating that it could be declared constant.
1428 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1430 -- Suppress warnings in internal units if not in -gnatg mode
1431 -- (these would be junk warnings for an applications program,
1432 -- since they refer to problems in internal units).
1436 Is_Internal_File_Name
1437 (Unit_File_Name (Get_Source_Unit (E1)))
1439 -- We do not immediately flag the error. This is because we
1440 -- have not expanded generic bodies yet, and they may have
1441 -- the missing reference. So instead we park the entity on a
1442 -- list, for later processing. However for the case of an
1443 -- accept statement we want to output messages now, since
1444 -- we know we already have all information at hand, and we
1445 -- also want to have separate warnings for each accept
1446 -- statement for the same entry.
1448 if Present (Anod) then
1449 pragma Assert (Is_Formal (E1));
1451 -- The unreferenced entity is E1, but post the warning
1452 -- on the body entity for this accept statement.
1454 if not Warnings_Off_E1 then
1455 Warn_On_Unreferenced_Entity
1456 (E1, Body_Formal (E1, Accept_Statement => Anod));
1459 elsif not Warnings_Off_E1 then
1460 Unreferenced_Entities.Append (E1);
1464 -- Generic units are referenced in the generic body, but if they
1465 -- are not public and never instantiated we want to force a
1466 -- warning on them. We treat them as redundant constructs to
1469 elsif Is_Generic_Subprogram (E1)
1470 and then not Is_Instantiated (E1)
1471 and then not Publicly_Referenceable (E1)
1472 and then Instantiation_Depth (Sloc (E1)) = 0
1473 and then Warn_On_Redundant_Constructs
1475 if not Warnings_Off_E1 then
1476 Unreferenced_Entities.Append (E1);
1478 -- Force warning on entity
1480 Set_Referenced (E1, False);
1485 -- Recurse into nested package or block. Do not recurse into a formal
1486 -- package, because the corresponding body is not analyzed.
1489 if (Is_Package_Or_Generic_Package (E1)
1490 and then Nkind (Parent (E1)) = N_Package_Specification
1492 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1493 /= N_Formal_Package_Declaration)
1495 or else Ekind (E1) = E_Block
1497 Check_References (E1);
1502 end Check_References;
1504 ---------------------------
1505 -- Check_Unset_Reference --
1506 ---------------------------
1508 procedure Check_Unset_Reference (N : Node_Id) is
1509 Typ : constant Entity_Id := Etype (N);
1511 function Is_OK_Fully_Initialized return Boolean;
1512 -- This function returns true if the given node N is fully initialized
1513 -- so that the reference is safe as far as this routine is concerned.
1514 -- Safe generally means that the type of N is a fully initialized type.
1515 -- The one special case is that for access types, which are always fully
1516 -- initialized, we don't consider a dereference OK since it will surely
1517 -- be dereferencing a null value, which won't do.
1519 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1520 -- Used to test indexed or selected component or slice to see if the
1521 -- evaluation of the prefix depends on a dereference, and if so, returns
1522 -- True, in which case we always check the prefix, even if we know that
1523 -- the referenced component is initialized. Pref is the prefix to test.
1525 -----------------------------
1526 -- Is_OK_Fully_Initialized --
1527 -----------------------------
1529 function Is_OK_Fully_Initialized return Boolean is
1531 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1534 return Is_Fully_Initialized_Type (Typ);
1536 end Is_OK_Fully_Initialized;
1538 ----------------------------
1539 -- Prefix_Has_Dereference --
1540 ----------------------------
1542 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1544 -- If prefix is of an access type, it certainly needs a dereference
1546 if Is_Access_Type (Etype (Pref)) then
1549 -- If prefix is explicit dereference, that's a dereference for sure
1551 elsif Nkind (Pref) = N_Explicit_Dereference then
1554 -- If prefix is itself a component reference or slice check prefix
1556 elsif Nkind (Pref) = N_Slice
1557 or else Nkind (Pref) = N_Indexed_Component
1558 or else Nkind (Pref) = N_Selected_Component
1560 return Prefix_Has_Dereference (Prefix (Pref));
1562 -- All other cases do not involve a dereference
1567 end Prefix_Has_Dereference;
1569 -- Start of processing for Check_Unset_Reference
1572 -- Nothing to do if warnings suppressed
1574 if Warning_Mode = Suppress then
1578 -- Ignore reference unless it comes from source. Almost always if we
1579 -- have a reference from generated code, it is bogus (e.g. calls to init
1580 -- procs to set default discriminant values).
1582 if not Comes_From_Source (N) then
1586 -- Otherwise see what kind of node we have. If the entity already has an
1587 -- unset reference, it is not necessarily the earliest in the text,
1588 -- because resolution of the prefix of selected components is completed
1589 -- before the resolution of the selected component itself. As a result,
1590 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1591 -- in right-to-left order. If there is already an unset reference, we
1592 -- check whether N is earlier before proceeding.
1596 -- For identifier or expanded name, examine the entity involved
1598 when N_Identifier | N_Expanded_Name =>
1600 E : constant Entity_Id := Entity (N);
1603 if (Ekind (E) = E_Variable
1605 Ekind (E) = E_Out_Parameter)
1606 and then Never_Set_In_Source_Check_Spec (E)
1607 and then not Has_Initial_Value (E)
1608 and then (No (Unset_Reference (E))
1610 Earlier_In_Extended_Unit
1611 (Sloc (N), Sloc (Unset_Reference (E))))
1612 and then not Has_Pragma_Unmodified_Check_Spec (E)
1613 and then not Warnings_Off_Check_Spec (E)
1615 -- We may have an unset reference. The first test is whether
1616 -- this is an access to a discriminant of a record or a
1617 -- component with default initialization. Both of these
1618 -- cases can be ignored, since the actual object that is
1619 -- referenced is definitely initialized. Note that this
1620 -- covers the case of reading discriminants of an OUT
1621 -- parameter, which is OK even in Ada 83.
1623 -- Note that we are only interested in a direct reference to
1624 -- a record component here. If the reference is through an
1625 -- access type, then the access object is being referenced,
1626 -- not the record, and still deserves an unset reference.
1628 if Nkind (Parent (N)) = N_Selected_Component
1629 and not Is_Access_Type (Typ)
1632 ES : constant Entity_Id :=
1633 Entity (Selector_Name (Parent (N)));
1635 if Ekind (ES) = E_Discriminant
1637 (Present (Declaration_Node (ES))
1639 Present (Expression (Declaration_Node (ES))))
1646 -- Exclude fully initialized types
1648 if Is_OK_Fully_Initialized then
1652 -- Here we have a potential unset reference. But before we
1653 -- get worried about it, we have to make sure that the
1654 -- entity declaration is in the same procedure as the
1655 -- reference, since if they are in separate procedures, then
1656 -- we have no idea about sequential execution.
1658 -- The tests in the loop below catch all such cases, but do
1659 -- allow the reference to appear in a loop, block, or
1660 -- package spec that is nested within the declaring scope.
1661 -- As always, it is possible to construct cases where the
1662 -- warning is wrong, that is why it is a warning!
1664 Potential_Unset_Reference : declare
1666 SE : constant Entity_Id := Scope (E);
1668 function Within_Postcondition return Boolean;
1669 -- Returns True iff N is within a Precondition
1671 --------------------------
1672 -- Within_Postcondition --
1673 --------------------------
1675 function Within_Postcondition return Boolean is
1680 while Present (Nod) loop
1681 if Nkind (Nod) = N_Pragma
1682 and then Pragma_Name (Nod) = Name_Postcondition
1687 Nod := Parent (Nod);
1691 end Within_Postcondition;
1693 -- Start of processing for Potential_Unset_Reference
1696 SR := Current_Scope;
1698 if SR = Standard_Standard
1699 or else Is_Subprogram (SR)
1700 or else Is_Concurrent_Body (SR)
1701 or else Is_Concurrent_Type (SR)
1709 -- Case of reference has an access type. This is a
1710 -- special case since access types are always set to null
1711 -- so cannot be truly uninitialized, but we still want to
1712 -- warn about cases of obvious null dereference.
1714 if Is_Access_Type (Typ) then
1715 Access_Type_Case : declare
1719 (N : Node_Id) return Traverse_Result;
1720 -- Process function for instantiation of Traverse
1721 -- below. Checks if N contains reference to E other
1722 -- than a dereference.
1724 function Ref_In (Nod : Node_Id) return Boolean;
1725 -- Determines whether Nod contains a reference to
1726 -- the entity E that is not a dereference.
1733 (N : Node_Id) return Traverse_Result
1736 if Is_Entity_Name (N)
1737 and then Entity (N) = E
1738 and then not Is_Dereferenced (N)
1750 function Ref_In (Nod : Node_Id) return Boolean is
1751 function Traverse is new Traverse_Func (Process);
1753 return Traverse (Nod) = Abandon;
1756 -- Start of processing for Access_Type_Case
1759 -- Don't bother if we are inside an instance, since
1760 -- the compilation of the generic template is where
1761 -- the warning should be issued.
1767 -- Don't bother if this is not the main unit. If we
1768 -- try to give this warning for with'ed units, we
1769 -- get some false positives, since we do not record
1770 -- references in other units.
1772 if not In_Extended_Main_Source_Unit (E)
1774 not In_Extended_Main_Source_Unit (N)
1779 -- We are only interested in dereferences
1781 if not Is_Dereferenced (N) then
1785 -- One more check, don't bother with references
1786 -- that are inside conditional statements or WHILE
1787 -- loops if the condition references the entity in
1788 -- question. This avoids most false positives.
1795 if (Nkind (P) = N_If_Statement
1797 Nkind (P) = N_Elsif_Part)
1798 and then Ref_In (Condition (P))
1802 elsif Nkind (P) = N_Loop_Statement
1803 and then Present (Iteration_Scheme (P))
1805 Ref_In (Condition (Iteration_Scheme (P)))
1810 end Access_Type_Case;
1813 -- One more check, don't bother if we are within a
1814 -- postcondition pragma, since the expression occurs
1815 -- in a place unrelated to the actual test.
1817 if not Within_Postcondition then
1819 -- Here we definitely have a case for giving a warning
1820 -- for a reference to an unset value. But we don't
1821 -- give the warning now. Instead set Unset_Reference
1822 -- in the identifier involved. The reason for this is
1823 -- that if we find the variable is never ever assigned
1824 -- a value then that warning is more important and
1825 -- there is no point in giving the reference warning.
1827 -- If this is an identifier, set the field directly
1829 if Nkind (N) = N_Identifier then
1830 Set_Unset_Reference (E, N);
1832 -- Otherwise it is an expanded name, so set the field
1833 -- of the actual identifier for the reference.
1836 Set_Unset_Reference (E, Selector_Name (N));
1839 end Potential_Unset_Reference;
1843 -- Indexed component or slice
1845 when N_Indexed_Component | N_Slice =>
1847 -- If prefix does not involve dereferencing an access type, then
1848 -- we know we are OK if the component type is fully initialized,
1849 -- since the component will have been set as part of the default
1852 if not Prefix_Has_Dereference (Prefix (N))
1853 and then Is_OK_Fully_Initialized
1857 -- Look at prefix in access type case, or if the component is not
1858 -- fully initialized.
1861 Check_Unset_Reference (Prefix (N));
1866 when N_Selected_Component =>
1868 Pref : constant Node_Id := Prefix (N);
1869 Ent : constant Entity_Id := Entity (Selector_Name (N));
1872 -- If prefix involves dereferencing an access type, always
1873 -- check the prefix, since the issue then is whether this
1874 -- access value is null.
1876 if Prefix_Has_Dereference (Pref) then
1879 -- Always go to prefix if no selector entity is set. Can this
1880 -- happen in the normal case? Not clear, but it definitely can
1881 -- happen in error cases.
1886 -- For a record component, check some cases where we have
1887 -- reasonable cause to consider that the component is known to
1888 -- be or probably is initialized. In this case, we don't care
1889 -- if the prefix itself was explicitly initialized.
1891 -- Discriminants are always considered initialized
1893 elsif Ekind (Ent) = E_Discriminant then
1896 -- An explicitly initialized component is certainly initialized
1898 elsif Nkind (Parent (Ent)) = N_Component_Declaration
1899 and then Present (Expression (Parent (Ent)))
1903 -- A fully initialized component is initialized
1905 elsif Is_OK_Fully_Initialized then
1909 -- If none of those cases apply, check the record type prefix
1911 Check_Unset_Reference (Pref);
1914 -- For type conversions or qualifications examine the expression
1916 when N_Type_Conversion | N_Qualified_Expression =>
1917 Check_Unset_Reference (Expression (N));
1919 -- For explicit dereference, always check prefix, which will generate
1920 -- an unset reference (since this is a case of dereferencing null).
1922 when N_Explicit_Dereference =>
1923 Check_Unset_Reference (Prefix (N));
1925 -- All other cases are not cases of an unset reference
1931 end Check_Unset_Reference;
1933 ------------------------
1934 -- Check_Unused_Withs --
1935 ------------------------
1937 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
1943 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
1944 -- This is needed for checking the special renaming case
1946 procedure Check_One_Unit (Unit : Unit_Number_Type);
1947 -- Subsidiary procedure, performs checks for specified unit
1949 --------------------
1950 -- Check_One_Unit --
1951 --------------------
1953 procedure Check_One_Unit (Unit : Unit_Number_Type) is
1954 Is_Visible_Renaming : Boolean := False;
1957 procedure Check_Inner_Package (Pack : Entity_Id);
1958 -- Pack is a package local to a unit in a with_clause. Both the unit
1959 -- and Pack are referenced. If none of the entities in Pack are
1960 -- referenced, then the only occurrence of Pack is in a USE clause
1961 -- or a pragma, and a warning is worthwhile as well.
1963 function Check_System_Aux return Boolean;
1964 -- Before giving a warning on a with_clause for System, check wheter
1965 -- a system extension is present.
1967 function Find_Package_Renaming
1969 L : Entity_Id) return Entity_Id;
1970 -- The only reference to a context unit may be in a renaming
1971 -- declaration. If this renaming declares a visible entity, do not
1972 -- warn that the context clause could be moved to the body, because
1973 -- the renaming may be intended to re-export the unit.
1975 function Has_Visible_Entities (P : Entity_Id) return Boolean;
1976 -- This function determines if a package has any visible entities.
1977 -- True is returned if there is at least one declared visible entity,
1978 -- otherwise False is returned (e.g. case of only pragmas present).
1980 -------------------------
1981 -- Check_Inner_Package --
1982 -------------------------
1984 procedure Check_Inner_Package (Pack : Entity_Id) is
1986 Un : constant Node_Id := Sinfo.Unit (Cnode);
1988 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
1989 -- If N is a use_clause for Pack, emit warning
1991 procedure Check_Use_Clauses is new
1992 Traverse_Proc (Check_Use_Clause);
1994 ----------------------
1995 -- Check_Use_Clause --
1996 ----------------------
1998 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2002 if Nkind (N) = N_Use_Package_Clause then
2003 Nam := First (Names (N));
2004 while Present (Nam) loop
2005 if Entity (Nam) = Pack then
2006 Error_Msg_Qual_Level := 1;
2008 ("?no entities of package& are referenced!",
2010 Error_Msg_Qual_Level := 0;
2018 end Check_Use_Clause;
2020 -- Start of processing for Check_Inner_Package
2023 E := First_Entity (Pack);
2024 while Present (E) loop
2025 if Referenced_Check_Spec (E) then
2032 -- No entities of the package are referenced. Check whether the
2033 -- reference to the package itself is a use clause, and if so
2034 -- place a warning on it.
2036 Check_Use_Clauses (Un);
2037 end Check_Inner_Package;
2039 ----------------------
2040 -- Check_System_Aux --
2041 ----------------------
2043 function Check_System_Aux return Boolean is
2047 if Chars (Lunit) = Name_System
2048 and then Scope (Lunit) = Standard_Standard
2049 and then Present_System_Aux
2051 Ent := First_Entity (System_Aux_Id);
2052 while Present (Ent) loop
2053 if Referenced_Check_Spec (Ent) then
2062 end Check_System_Aux;
2064 ---------------------------
2065 -- Find_Package_Renaming --
2066 ---------------------------
2068 function Find_Package_Renaming
2070 L : Entity_Id) return Entity_Id
2076 Is_Visible_Renaming := False;
2078 E1 := First_Entity (P);
2079 while Present (E1) loop
2080 if Ekind (E1) = E_Package
2081 and then Renamed_Object (E1) = L
2083 Is_Visible_Renaming := not Is_Hidden (E1);
2086 elsif Ekind (E1) = E_Package
2087 and then No (Renamed_Object (E1))
2088 and then not Is_Generic_Instance (E1)
2090 R := Find_Package_Renaming (E1, L);
2093 Is_Visible_Renaming := not Is_Hidden (R);
2102 end Find_Package_Renaming;
2104 --------------------------
2105 -- Has_Visible_Entities --
2106 --------------------------
2108 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2112 -- If unit in context is not a package, it is a subprogram that
2113 -- is not called or a generic unit that is not instantiated
2114 -- in the current unit, and warning is appropriate.
2116 if Ekind (P) /= E_Package then
2120 -- If unit comes from a limited_with clause, look for declaration
2121 -- of shadow entities.
2123 if Present (Limited_View (P)) then
2124 E := First_Entity (Limited_View (P));
2126 E := First_Entity (P);
2130 and then E /= First_Private_Entity (P)
2132 if Comes_From_Source (E)
2133 or else Present (Limited_View (P))
2142 end Has_Visible_Entities;
2144 -- Start of processing for Check_One_Unit
2147 Cnode := Cunit (Unit);
2149 -- Only do check in units that are part of the extended main unit.
2150 -- This is actually a necessary restriction, because in the case of
2151 -- subprogram acting as its own specification, there can be with's in
2152 -- subunits that we will not see.
2154 if not In_Extended_Main_Source_Unit (Cnode) then
2157 -- In configurable run time mode, we remove the bodies of non-inlined
2158 -- subprograms, which may lead to spurious warnings, which are
2159 -- clearly undesirable.
2161 elsif Configurable_Run_Time_Mode
2162 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2167 -- Loop through context items in this unit
2169 Item := First (Context_Items (Cnode));
2170 while Present (Item) loop
2171 if Nkind (Item) = N_With_Clause
2172 and then not Implicit_With (Item)
2173 and then In_Extended_Main_Source_Unit (Item)
2175 Lunit := Entity (Name (Item));
2177 -- Check if this unit is referenced (skip the check if this
2178 -- is explicitly marked by a pragma Unreferenced).
2180 if not Referenced (Lunit)
2181 and then not Has_Unreferenced (Lunit)
2183 -- Suppress warnings in internal units if not in -gnatg mode
2184 -- (these would be junk warnings for an application program,
2185 -- since they refer to problems in internal units).
2188 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2190 -- Here we definitely have a non-referenced unit. If it
2191 -- is the special call for a spec unit, then just set the
2192 -- flag to be read later.
2194 if Unit = Spec_Unit then
2195 Set_Unreferenced_In_Spec (Item);
2197 -- Otherwise simple unreferenced message, but skip this
2198 -- if no visible entities, because that is most likely a
2199 -- case where warning would be false positive (e.g. a
2200 -- package with only a linker options pragma and nothing
2201 -- else or a pragma elaborate with a body library task).
2203 elsif Has_Visible_Entities (Entity (Name (Item))) then
2205 ("?unit& is not referenced!", Name (Item));
2209 -- If main unit is a renaming of this unit, then we consider
2210 -- the with to be OK (obviously it is needed in this case!)
2211 -- This may be transitive: the unit in the with_clause may
2212 -- itself be a renaming, in which case both it and the main
2213 -- unit rename the same ultimate package.
2215 elsif Present (Renamed_Entity (Munite))
2217 (Renamed_Entity (Munite) = Lunit
2218 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2222 -- If this unit is referenced, and it is a package, we do
2223 -- another test, to see if any of the entities in the package
2224 -- are referenced. If none of the entities are referenced, we
2225 -- still post a warning. This occurs if the only use of the
2226 -- package is in a use clause, or in a package renaming
2227 -- declaration. This check is skipped for packages that are
2228 -- renamed in a spec, since the entities in such a package are
2229 -- visible to clients via the renaming.
2231 elsif Ekind (Lunit) = E_Package
2232 and then not Renamed_In_Spec (Lunit)
2234 -- If Is_Instantiated is set, it means that the package is
2235 -- implicitly instantiated (this is the case of parent
2236 -- instance or an actual for a generic package formal), and
2237 -- this counts as a reference.
2239 if Is_Instantiated (Lunit) then
2242 -- If no entities in package, and there is a pragma
2243 -- Elaborate_Body present, then assume that this with is
2244 -- done for purposes of this elaboration.
2246 elsif No (First_Entity (Lunit))
2247 and then Has_Pragma_Elaborate_Body (Lunit)
2251 -- Otherwise see if any entities have been referenced
2254 if Limited_Present (Item) then
2255 Ent := First_Entity (Limited_View (Lunit));
2257 Ent := First_Entity (Lunit);
2261 -- No more entities, and we did not find one that was
2262 -- referenced. Means we have a definite case of a with
2263 -- none of whose entities was referenced.
2267 -- If in spec, just set the flag
2269 if Unit = Spec_Unit then
2270 Set_No_Entities_Ref_In_Spec (Item);
2272 elsif Check_System_Aux then
2275 -- Else give the warning
2279 Has_Unreferenced (Entity (Name (Item)))
2282 ("?no entities of & are referenced!",
2286 -- Look for renamings of this package, and flag
2287 -- them as well. If the original package has
2288 -- warnings off, we suppress the warning on the
2289 -- renaming as well.
2291 Pack := Find_Package_Renaming (Munite, Lunit);
2294 and then not Has_Warnings_Off (Lunit)
2295 and then not Has_Unreferenced (Pack)
2298 ("?no entities of & are referenced!",
2299 Unit_Declaration_Node (Pack),
2306 -- Case of entity being referenced. The reference may
2307 -- come from a limited_with_clause, in which case the
2308 -- limited view of the entity carries the flag.
2310 elsif Referenced_Check_Spec (Ent)
2311 or else Referenced_As_LHS_Check_Spec (Ent)
2312 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2314 (From_With_Type (Ent)
2315 and then Is_Incomplete_Type (Ent)
2316 and then Present (Non_Limited_View (Ent))
2317 and then Referenced (Non_Limited_View (Ent)))
2319 -- This means that the with is indeed fine, in that
2320 -- it is definitely needed somewhere, and we can
2321 -- quit worrying about this one...
2323 -- Except for one little detail: if either of the
2324 -- flags was set during spec processing, this is
2325 -- where we complain that the with could be moved
2326 -- from the spec. If the spec contains a visible
2327 -- renaming of the package, inhibit warning to move
2328 -- with_clause to body.
2330 if Ekind (Munite) = E_Package_Body then
2332 Find_Package_Renaming
2333 (Spec_Entity (Munite), Lunit);
2336 if Unreferenced_In_Spec (Item) then
2338 ("?unit& is not referenced in spec!",
2341 elsif No_Entities_Ref_In_Spec (Item) then
2343 ("?no entities of & are referenced in spec!",
2347 if Ekind (Ent) = E_Package then
2348 Check_Inner_Package (Ent);
2354 if not Is_Visible_Renaming then
2355 Error_Msg_N -- CODEFIX
2356 ("\?with clause might be moved to body!",
2362 -- Move to next entity to continue search
2370 -- For a generic package, the only interesting kind of
2371 -- reference is an instantiation, since entities cannot be
2372 -- referenced directly.
2374 elsif Is_Generic_Unit (Lunit) then
2376 -- Unit was never instantiated, set flag for case of spec
2377 -- call, or give warning for normal call.
2379 if not Is_Instantiated (Lunit) then
2380 if Unit = Spec_Unit then
2381 Set_Unreferenced_In_Spec (Item);
2383 Error_Msg_N -- CODEFIX
2384 ("?unit& is never instantiated!", Name (Item));
2387 -- If unit was indeed instantiated, make sure that flag is
2388 -- not set showing it was uninstantiated in the spec, and if
2389 -- so, give warning.
2391 elsif Unreferenced_In_Spec (Item) then
2393 ("?unit& is not instantiated in spec!", Name (Item));
2394 Error_Msg_N -- CODEFIX
2395 ("\?with clause can be moved to body!", Name (Item));
2404 -- Start of processing for Check_Unused_Withs
2407 if not Opt.Check_Withs
2408 or else Operating_Mode = Check_Syntax
2413 -- Flag any unused with clauses, but skip this step if we are compiling
2414 -- a subunit on its own, since we do not have enough information to
2415 -- determine whether with's are used. We will get the relevant warnings
2416 -- when we compile the parent. This is the normal style of GNAT
2417 -- compilation in any case.
2419 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2423 -- Process specified units
2425 if Spec_Unit = No_Unit then
2427 -- For main call, check all units
2429 for Unit in Main_Unit .. Last_Unit loop
2430 Check_One_Unit (Unit);
2434 -- For call for spec, check only the spec
2436 Check_One_Unit (Spec_Unit);
2438 end Check_Unused_Withs;
2440 ---------------------------------
2441 -- Generic_Package_Spec_Entity --
2442 ---------------------------------
2444 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2448 if Is_Package_Body_Entity (E) then
2454 if S = Standard_Standard then
2457 elsif Ekind (S) = E_Generic_Package then
2460 elsif Ekind (S) = E_Package then
2468 end Generic_Package_Spec_Entity;
2470 ----------------------
2471 -- Goto_Spec_Entity --
2472 ----------------------
2474 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2477 and then Present (Spec_Entity (E))
2479 return Spec_Entity (E);
2483 end Goto_Spec_Entity;
2485 --------------------------------------
2486 -- Has_Pragma_Unmodified_Check_Spec --
2487 --------------------------------------
2489 function Has_Pragma_Unmodified_Check_Spec
2490 (E : Entity_Id) return Boolean
2493 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2495 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2496 -- to mess with Unmodified flags on both body and spec entities.
2498 return Has_Unmodified (E)
2500 Has_Unmodified (Spec_Entity (E));
2503 return Has_Unmodified (E);
2505 end Has_Pragma_Unmodified_Check_Spec;
2507 ----------------------------------------
2508 -- Has_Pragma_Unreferenced_Check_Spec --
2509 ----------------------------------------
2511 function Has_Pragma_Unreferenced_Check_Spec
2512 (E : Entity_Id) return Boolean
2515 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2517 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2518 -- to mess with flags on both entities.
2520 return Has_Unreferenced (E)
2522 Has_Unreferenced (Spec_Entity (E));
2525 return Has_Unreferenced (E);
2527 end Has_Pragma_Unreferenced_Check_Spec;
2533 procedure Initialize is
2535 Warnings_Off_Pragmas.Init;
2536 Unreferenced_Entities.Init;
2537 In_Out_Warnings.Init;
2540 ------------------------------------
2541 -- Never_Set_In_Source_Check_Spec --
2542 ------------------------------------
2544 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2546 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2547 return Never_Set_In_Source (E)
2549 Never_Set_In_Source (Spec_Entity (E));
2551 return Never_Set_In_Source (E);
2553 end Never_Set_In_Source_Check_Spec;
2555 -------------------------------------
2556 -- Operand_Has_Warnings_Suppressed --
2557 -------------------------------------
2559 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2561 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2562 -- Function used to check one node to see if it is or was originally
2563 -- a reference to an entity for which Warnings are off. If so, Abandon
2564 -- is returned, otherwise OK_Orig is returned to continue the traversal
2565 -- of the original expression.
2567 function Traverse is new Traverse_Func (Check_For_Warnings);
2568 -- Function used to traverse tree looking for warnings
2570 ------------------------
2571 -- Check_For_Warnings --
2572 ------------------------
2574 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2575 R : constant Node_Id := Original_Node (N);
2578 if Nkind (R) in N_Has_Entity
2579 and then Present (Entity (R))
2580 and then Has_Warnings_Off (Entity (R))
2586 end Check_For_Warnings;
2588 -- Start of processing for Operand_Has_Warnings_Suppressed
2591 return Traverse (N) = Abandon;
2593 -- If any exception occurs, then something has gone wrong, and this is
2594 -- only a minor aesthetic issue anyway, so just say we did not find what
2595 -- we are looking for, rather than blow up.
2600 end Operand_Has_Warnings_Suppressed;
2602 -----------------------------------------
2603 -- Output_Non_Modified_In_Out_Warnings --
2604 -----------------------------------------
2606 procedure Output_Non_Modified_In_Out_Warnings is
2608 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2609 -- Given a formal parameter entity E, determines if there is a reason to
2610 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2611 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2612 -- if we have seen the address of the subprogram being taken, or if the
2613 -- subprogram is used as a generic actual (in the latter cases the
2614 -- context may force use of IN OUT, even if the parameter is not
2615 -- modifies for this particular case.
2617 -----------------------
2618 -- No_Warn_On_In_Out --
2619 -----------------------
2621 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2622 S : constant Entity_Id := Scope (E);
2623 SE : constant Entity_Id := Spec_Entity (E);
2626 -- Do not warn if address is taken, since funny business may be going
2627 -- on in treating the parameter indirectly as IN OUT.
2629 if Address_Taken (S)
2630 or else (Present (SE) and then Address_Taken (Scope (SE)))
2634 -- Do not warn if used as a generic actual, since the generic may be
2635 -- what is forcing the use of an "unnecessary" IN OUT.
2637 elsif Used_As_Generic_Actual (S)
2638 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2642 -- Else test warnings off
2644 elsif Warnings_Off_Check_Spec (S) then
2647 -- All tests for suppressing warning failed
2652 end No_Warn_On_In_Out;
2654 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2657 -- Loop through entities for which a warning may be needed
2659 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2661 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2664 -- Suppress warning in specific cases (see details in comments for
2665 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2667 if Has_Pragma_Unmodified_Check_Spec (E1)
2668 or else No_Warn_On_In_Out (E1)
2672 -- Here we generate the warning
2675 -- If -gnatwc is set then output message that we could be IN
2677 if not Is_Trivial_Subprogram (Scope (E1)) then
2678 if Warn_On_Constant then
2680 ("?formal parameter & is not modified!", E1);
2682 ("\?mode could be IN instead of `IN OUT`!", E1);
2684 -- We do not generate warnings for IN OUT parameters
2685 -- unless we have at least -gnatwu. This is deliberately
2686 -- inconsistent with the treatment of variables, but
2687 -- otherwise we get too many unexpected warnings in
2690 elsif Check_Unreferenced then
2691 Error_Msg_N ("?formal parameter& is read but "
2692 & "never assigned!", E1);
2696 -- Kill any other warnings on this entity, since this is the
2697 -- one that should dominate any other unreferenced warning.
2699 Set_Warnings_Off (E1);
2703 end Output_Non_Modified_In_Out_Warnings;
2705 ----------------------------------------
2706 -- Output_Obsolescent_Entity_Warnings --
2707 ----------------------------------------
2709 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2710 P : constant Node_Id := Parent (N);
2716 -- Do not output message if we are the scope of standard. This means
2717 -- we have a reference from a context clause from when it is originally
2718 -- processed, and that's too early to tell whether it is an obsolescent
2719 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2720 -- sure that we have a later call when the scope is available. This test
2721 -- also eliminates all messages for use clauses, which is fine (we do
2722 -- not want messages for use clauses, since they are always redundant
2723 -- with respect to the associated with clause).
2725 if S = Standard_Standard then
2729 -- Do not output message if we are in scope of an obsolescent package
2733 if Is_Obsolescent (S) then
2738 exit when S = Standard_Standard;
2741 -- Here we will output the message
2743 Error_Msg_Sloc := Sloc (E);
2745 -- Case of with clause
2747 if Nkind (P) = N_With_Clause then
2748 if Ekind (E) = E_Package then
2750 ("?with of obsolescent package& declared#", N, E);
2751 elsif Ekind (E) = E_Procedure then
2753 ("?with of obsolescent procedure& declared#", N, E);
2756 ("?with of obsolescent function& declared#", N, E);
2759 -- If we do not have a with clause, then ignore any reference to an
2760 -- obsolescent package name. We only want to give the one warning of
2761 -- withing the package, not one each time it is used to qualify.
2763 elsif Ekind (E) = E_Package then
2766 -- Procedure call statement
2768 elsif Nkind (P) = N_Procedure_Call_Statement then
2770 ("?call to obsolescent procedure& declared#", N, E);
2774 elsif Nkind (P) = N_Function_Call then
2776 ("?call to obsolescent function& declared#", N, E);
2778 -- Reference to obsolescent type
2780 elsif Is_Type (E) then
2782 ("?reference to obsolescent type& declared#", N, E);
2784 -- Reference to obsolescent component
2786 elsif Ekind (E) = E_Component
2787 or else Ekind (E) = E_Discriminant
2790 ("?reference to obsolescent component& declared#", N, E);
2792 -- Reference to obsolescent variable
2794 elsif Ekind (E) = E_Variable then
2796 ("?reference to obsolescent variable& declared#", N, E);
2798 -- Reference to obsolescent constant
2800 elsif Ekind (E) = E_Constant
2801 or else Ekind (E) in Named_Kind
2804 ("?reference to obsolescent constant& declared#", N, E);
2806 -- Reference to obsolescent enumeration literal
2808 elsif Ekind (E) = E_Enumeration_Literal then
2810 ("?reference to obsolescent enumeration literal& declared#", N, E);
2812 -- Generic message for any other case we missed
2816 ("?reference to obsolescent entity& declared#", N, E);
2819 -- Output additional warning if present
2821 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2822 if Obsolescent_Warnings.Table (J).Ent = E then
2823 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2824 Error_Msg_Strlen := Name_Len;
2825 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2826 Error_Msg_N ("\\?~", N);
2830 end Output_Obsolescent_Entity_Warnings;
2832 ----------------------------------
2833 -- Output_Unreferenced_Messages --
2834 ----------------------------------
2836 procedure Output_Unreferenced_Messages is
2838 for J in Unreferenced_Entities.First ..
2839 Unreferenced_Entities.Last
2841 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2843 end Output_Unreferenced_Messages;
2845 -----------------------------------------
2846 -- Output_Unused_Warnings_Off_Warnings --
2847 -----------------------------------------
2849 procedure Output_Unused_Warnings_Off_Warnings is
2851 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2853 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2854 N : Node_Id renames Wentry.N;
2855 E : Node_Id renames Wentry.E;
2858 -- Turn off Warnings_Off, or we won't get the warning!
2860 Set_Warnings_Off (E, False);
2862 -- Nothing to do if pragma was used to suppress a general warning
2864 if Warnings_Off_Used (E) then
2867 -- If pragma was used both in unmodified and unreferenced contexts
2868 -- then that's as good as the general case, no warning.
2870 elsif Warnings_Off_Used_Unmodified (E)
2872 Warnings_Off_Used_Unreferenced (E)
2876 -- Used only in context where Unmodified would have worked
2878 elsif Warnings_Off_Used_Unmodified (E) then
2880 ("?could use Unmodified instead of "
2881 & "Warnings Off for &", Pragma_Identifier (N), E);
2883 -- Used only in context where Unreferenced would have worked
2885 elsif Warnings_Off_Used_Unreferenced (E) then
2887 ("?could use Unreferenced instead of "
2888 & "Warnings Off for &", Pragma_Identifier (N), E);
2894 ("?pragma Warnings Off for & unused, "
2895 & "could be omitted", N, E);
2899 end Output_Unused_Warnings_Off_Warnings;
2901 ---------------------------
2902 -- Referenced_Check_Spec --
2903 ---------------------------
2905 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
2907 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2908 return Referenced (E) or else Referenced (Spec_Entity (E));
2910 return Referenced (E);
2912 end Referenced_Check_Spec;
2914 ----------------------------------
2915 -- Referenced_As_LHS_Check_Spec --
2916 ----------------------------------
2918 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
2920 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2921 return Referenced_As_LHS (E)
2922 or else Referenced_As_LHS (Spec_Entity (E));
2924 return Referenced_As_LHS (E);
2926 end Referenced_As_LHS_Check_Spec;
2928 --------------------------------------------
2929 -- Referenced_As_Out_Parameter_Check_Spec --
2930 --------------------------------------------
2932 function Referenced_As_Out_Parameter_Check_Spec
2933 (E : Entity_Id) return Boolean
2936 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2937 return Referenced_As_Out_Parameter (E)
2938 or else Referenced_As_Out_Parameter (Spec_Entity (E));
2940 return Referenced_As_Out_Parameter (E);
2942 end Referenced_As_Out_Parameter_Check_Spec;
2944 ----------------------------
2945 -- Set_Dot_Warning_Switch --
2946 ----------------------------
2948 function Set_Dot_Warning_Switch (C : Character) return Boolean is
2952 Warn_On_Assertion_Failure := True;
2955 Warn_On_Assertion_Failure := False;
2958 Warn_On_Biased_Representation := True;
2961 Warn_On_Biased_Representation := False;
2964 Warn_On_Unrepped_Components := True;
2967 Warn_On_Unrepped_Components := False;
2970 Address_Clause_Overlay_Warnings := True;
2971 Check_Unreferenced := True;
2972 Check_Unreferenced_Formals := True;
2973 Check_Withs := True;
2974 Constant_Condition_Warnings := True;
2975 Elab_Warnings := True;
2976 Implementation_Unit_Warnings := True;
2977 Ineffective_Inline_Warnings := True;
2978 Warn_On_Ada_2005_Compatibility := True;
2979 Warn_On_All_Unread_Out_Parameters := True;
2980 Warn_On_Assertion_Failure := True;
2981 Warn_On_Assumed_Low_Bound := True;
2982 Warn_On_Bad_Fixed_Value := True;
2983 Warn_On_Biased_Representation := True;
2984 Warn_On_Constant := True;
2985 Warn_On_Deleted_Code := True;
2986 Warn_On_Dereference := True;
2987 Warn_On_Export_Import := True;
2988 Warn_On_Hiding := True;
2989 Warn_On_Modified_Unread := True;
2990 Warn_On_No_Value_Assigned := True;
2991 Warn_On_Non_Local_Exception := True;
2992 Warn_On_Object_Renames_Function := True;
2993 Warn_On_Obsolescent_Feature := True;
2994 Warn_On_Questionable_Missing_Parens := True;
2995 Warn_On_Redundant_Constructs := True;
2996 Warn_On_Unchecked_Conversion := True;
2997 Warn_On_Unrecognized_Pragma := True;
2998 Warn_On_Unrepped_Components := True;
2999 Warn_On_Warnings_Off := True;
3002 Set_GNAT_Mode_Warnings;
3005 Warn_On_Suspicious_Modulus_Value := True;
3008 Warn_On_Suspicious_Modulus_Value := False;
3011 Warn_On_All_Unread_Out_Parameters := True;
3014 Warn_On_All_Unread_Out_Parameters := False;
3017 Warn_On_Parameter_Order := True;
3020 Warn_On_Parameter_Order := False;
3023 Warn_On_Object_Renames_Function := True;
3026 Warn_On_Object_Renames_Function := False;
3029 Warn_On_Warnings_Off := True;
3032 Warn_On_Warnings_Off := False;
3035 Warn_On_Non_Local_Exception := True;
3038 Warn_On_Non_Local_Exception := False;
3039 No_Warn_On_Non_Local_Exception := True;
3046 end Set_Dot_Warning_Switch;
3048 ----------------------------
3049 -- Set_GNAT_Mode_Warnings --
3050 ----------------------------
3052 procedure Set_GNAT_Mode_Warnings is
3054 Address_Clause_Overlay_Warnings := True;
3055 Check_Unreferenced := True;
3056 Check_Unreferenced_Formals := True;
3057 Check_Withs := True;
3058 Constant_Condition_Warnings := True;
3059 Elab_Warnings := False;
3060 Implementation_Unit_Warnings := False;
3061 Ineffective_Inline_Warnings := True;
3062 Warn_On_Ada_2005_Compatibility := True;
3063 Warn_On_All_Unread_Out_Parameters := False;
3064 Warn_On_Assertion_Failure := True;
3065 Warn_On_Assumed_Low_Bound := True;
3066 Warn_On_Bad_Fixed_Value := True;
3067 Warn_On_Biased_Representation := True;
3068 Warn_On_Constant := True;
3069 Warn_On_Deleted_Code := False;
3070 Warn_On_Dereference := False;
3071 Warn_On_Export_Import := True;
3072 Warn_On_Hiding := False;
3073 Warn_On_Modified_Unread := True;
3074 Warn_On_No_Value_Assigned := True;
3075 Warn_On_Non_Local_Exception := False;
3076 Warn_On_Object_Renames_Function := False;
3077 Warn_On_Obsolescent_Feature := True;
3078 Warn_On_Questionable_Missing_Parens := True;
3079 Warn_On_Redundant_Constructs := True;
3080 Warn_On_Object_Renames_Function := True;
3081 Warn_On_Unchecked_Conversion := True;
3082 Warn_On_Unrecognized_Pragma := True;
3083 Warn_On_Unrepped_Components := False;
3084 Warn_On_Warnings_Off := False;
3085 end Set_GNAT_Mode_Warnings;
3087 ------------------------
3088 -- Set_Warning_Switch --
3089 ------------------------
3091 function Set_Warning_Switch (C : Character) return Boolean is
3095 Check_Unreferenced := True;
3096 Check_Unreferenced_Formals := True;
3097 Check_Withs := True;
3098 Constant_Condition_Warnings := True;
3099 Implementation_Unit_Warnings := True;
3100 Ineffective_Inline_Warnings := True;
3101 Warn_On_Ada_2005_Compatibility := True;
3102 Warn_On_Assertion_Failure := True;
3103 Warn_On_Assumed_Low_Bound := True;
3104 Warn_On_Bad_Fixed_Value := True;
3105 Warn_On_Biased_Representation := True;
3106 Warn_On_Constant := True;
3107 Warn_On_Export_Import := True;
3108 Warn_On_Modified_Unread := True;
3109 Warn_On_No_Value_Assigned := True;
3110 Warn_On_Non_Local_Exception := True;
3111 Warn_On_Object_Renames_Function := True;
3112 Warn_On_Obsolescent_Feature := True;
3113 Warn_On_Parameter_Order := True;
3114 Warn_On_Questionable_Missing_Parens := True;
3115 Warn_On_Redundant_Constructs := True;
3116 Warn_On_Unchecked_Conversion := True;
3117 Warn_On_Unrecognized_Pragma := True;
3118 Warn_On_Unrepped_Components := True;
3121 Check_Unreferenced := False;
3122 Check_Unreferenced_Formals := False;
3123 Check_Withs := False;
3124 Constant_Condition_Warnings := False;
3125 Elab_Warnings := False;
3126 Implementation_Unit_Warnings := False;
3127 Ineffective_Inline_Warnings := False;
3128 Warn_On_Ada_2005_Compatibility := False;
3129 Warn_On_Assertion_Failure := False;
3130 Warn_On_Assumed_Low_Bound := False;
3131 Warn_On_Bad_Fixed_Value := False;
3132 Warn_On_Biased_Representation := False;
3133 Warn_On_Constant := False;
3134 Warn_On_Deleted_Code := False;
3135 Warn_On_Dereference := False;
3136 Warn_On_Export_Import := False;
3137 Warn_On_Hiding := False;
3138 Warn_On_Modified_Unread := False;
3139 Warn_On_No_Value_Assigned := False;
3140 Warn_On_Non_Local_Exception := False;
3141 Warn_On_Obsolescent_Feature := False;
3142 Warn_On_All_Unread_Out_Parameters := False;
3143 Warn_On_Parameter_Order := False;
3144 Warn_On_Questionable_Missing_Parens := False;
3145 Warn_On_Redundant_Constructs := False;
3146 Warn_On_Object_Renames_Function := False;
3147 Warn_On_Unchecked_Conversion := False;
3148 Warn_On_Unrecognized_Pragma := False;
3149 Warn_On_Unrepped_Components := False;
3150 Warn_On_Warnings_Off := False;
3152 No_Warn_On_Non_Local_Exception := True;
3155 Warn_On_Bad_Fixed_Value := True;
3158 Warn_On_Bad_Fixed_Value := False;
3161 Constant_Condition_Warnings := True;
3164 Constant_Condition_Warnings := False;
3167 Warn_On_Dereference := True;
3170 Warn_On_Dereference := False;
3173 Warning_Mode := Treat_As_Error;
3176 Check_Unreferenced_Formals := True;
3179 Check_Unreferenced_Formals := False;
3182 Warn_On_Unrecognized_Pragma := True;
3185 Warn_On_Unrecognized_Pragma := False;
3188 Warn_On_Hiding := True;
3191 Warn_On_Hiding := False;
3194 Implementation_Unit_Warnings := True;
3197 Implementation_Unit_Warnings := False;
3200 Warn_On_Obsolescent_Feature := True;
3203 Warn_On_Obsolescent_Feature := False;
3206 Warn_On_Constant := True;
3209 Warn_On_Constant := False;
3212 Elab_Warnings := True;
3215 Elab_Warnings := False;
3218 Warn_On_Modified_Unread := True;
3221 Warn_On_Modified_Unread := False;
3224 Warning_Mode := Normal;
3227 Address_Clause_Overlay_Warnings := True;
3230 Address_Clause_Overlay_Warnings := False;
3233 Ineffective_Inline_Warnings := True;
3236 Ineffective_Inline_Warnings := False;
3239 Warn_On_Questionable_Missing_Parens := True;
3242 Warn_On_Questionable_Missing_Parens := False;
3245 Warn_On_Redundant_Constructs := True;
3248 Warn_On_Redundant_Constructs := False;
3251 Warning_Mode := Suppress;
3254 Warn_On_Deleted_Code := True;
3257 Warn_On_Deleted_Code := False;
3260 Check_Unreferenced := True;
3261 Check_Withs := True;
3262 Check_Unreferenced_Formals := True;
3265 Check_Unreferenced := False;
3266 Check_Withs := False;
3267 Check_Unreferenced_Formals := False;
3270 Warn_On_No_Value_Assigned := True;
3273 Warn_On_No_Value_Assigned := False;
3276 Warn_On_Assumed_Low_Bound := True;
3279 Warn_On_Assumed_Low_Bound := False;
3282 Warn_On_Export_Import := True;
3285 Warn_On_Export_Import := False;
3288 Warn_On_Ada_2005_Compatibility := True;
3291 Warn_On_Ada_2005_Compatibility := False;
3294 Warn_On_Unchecked_Conversion := True;
3297 Warn_On_Unchecked_Conversion := False;
3304 end Set_Warning_Switch;
3306 -----------------------------
3307 -- Warn_On_Known_Condition --
3308 -----------------------------
3310 procedure Warn_On_Known_Condition (C : Node_Id) is
3312 Orig : constant Node_Id := Original_Node (C);
3313 Test_Result : Boolean;
3315 function Is_Known_Branch return Boolean;
3316 -- If the type of the condition is Boolean, the constant value of the
3317 -- condition is a boolean literal. If the type is a derived boolean
3318 -- type, the constant is wrapped in a type conversion of the derived
3319 -- literal. If the value of the condition is not a literal, no warnings
3320 -- can be produced. This function returns True if the result can be
3321 -- determined, and Test_Result is set True/False accordingly. Otherwise
3322 -- False is returned, and Test_Result is unchanged.
3324 procedure Track (N : Node_Id; Loc : Node_Id);
3325 -- Adds continuation warning(s) pointing to reason (assignment or test)
3326 -- for the operand of the conditional having a known value (or at least
3327 -- enough is known about the value to issue the warning). N is the node
3328 -- which is judged to have a known value. Loc is the warning location.
3330 ---------------------
3331 -- Is_Known_Branch --
3332 ---------------------
3334 function Is_Known_Branch return Boolean is
3336 if Etype (C) = Standard_Boolean
3337 and then Is_Entity_Name (C)
3339 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3341 Test_Result := Entity (C) = Standard_True;
3344 elsif Is_Boolean_Type (Etype (C))
3345 and then Nkind (C) = N_Unchecked_Type_Conversion
3346 and then Is_Entity_Name (Expression (C))
3347 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3350 Chars (Entity (Expression (C))) = Chars (Standard_True);
3356 end Is_Known_Branch;
3362 procedure Track (N : Node_Id; Loc : Node_Id) is
3363 Nod : constant Node_Id := Original_Node (N);
3366 if Nkind (Nod) in N_Op_Compare then
3367 Track (Left_Opnd (Nod), Loc);
3368 Track (Right_Opnd (Nod), Loc);
3370 elsif Is_Entity_Name (Nod)
3371 and then Is_Object (Entity (Nod))
3374 CV : constant Node_Id := Current_Value (Entity (Nod));
3377 if Present (CV) then
3378 Error_Msg_Sloc := Sloc (CV);
3380 if Nkind (CV) not in N_Subexpr then
3381 Error_Msg_N ("\\?(see test #)", Loc);
3383 elsif Nkind (Parent (CV)) =
3384 N_Case_Statement_Alternative
3386 Error_Msg_N ("\\?(see case alternative #)", Loc);
3389 Error_Msg_N ("\\?(see assignment #)", Loc);
3396 -- Start of processing for Warn_On_Known_Condition
3399 -- Adjust SCO condition if from source
3402 and then Comes_From_Source (Orig)
3403 and then Is_Known_Branch
3412 Sloc_Range (Orig, Start, Dummy);
3413 Atrue := Test_Result;
3415 if Present (Parent (C))
3416 and then Nkind (Parent (C)) = N_Op_Not
3427 Set_SCO_Condition (Start, Typ);
3431 -- Argument replacement in an inlined body can make conditions static.
3432 -- Do not emit warnings in this case.
3434 if In_Inlined_Body then
3438 if Constant_Condition_Warnings
3439 and then Is_Known_Branch
3440 and then Comes_From_Source (Original_Node (C))
3441 and then not In_Instance
3443 -- See if this is in a statement or a declaration
3447 -- If tree is not attached, do not issue warning (this is very
3448 -- peculiar, and probably arises from some other error condition)
3453 -- If we are in a declaration, then no warning, since in practice
3454 -- conditionals in declarations are used for intended tests which
3455 -- may be known at compile time, e.g. things like
3457 -- x : constant Integer := 2 + (Word'Size = 32);
3459 -- And a warning is annoying in such cases
3461 elsif Nkind (P) in N_Declaration
3463 Nkind (P) in N_Later_Decl_Item
3467 -- Don't warn in assert or check pragma, since presumably tests in
3468 -- such a context are very definitely intended, and might well be
3469 -- known at compile time. Note that we have to test the original
3470 -- node, since assert pragmas get rewritten at analysis time.
3472 elsif Nkind (Original_Node (P)) = N_Pragma
3473 and then (Pragma_Name (Original_Node (P)) = Name_Assert
3475 Pragma_Name (Original_Node (P)) = Name_Check)
3480 exit when Is_Statement (P);
3484 -- Here we issue the warning unless some sub-operand has warnings
3485 -- set off, in which case we suppress the warning for the node. If
3486 -- the original expression is an inequality, it has been expanded
3487 -- into a negation, and the value of the original expression is the
3488 -- negation of the equality. If the expression is an entity that
3489 -- appears within a negation, it is clearer to flag the negation
3490 -- itself, and report on its constant value.
3492 if not Operand_Has_Warnings_Suppressed (C) then
3494 True_Branch : Boolean := Test_Result;
3495 Cond : Node_Id := C;
3498 if Present (Parent (C))
3499 and then Nkind (Parent (C)) = N_Op_Not
3501 True_Branch := not True_Branch;
3506 if Is_Entity_Name (Original_Node (C))
3507 and then Nkind (Cond) /= N_Op_Not
3510 ("object & is always True?", Cond, Original_Node (C));
3511 Track (Original_Node (C), Cond);
3514 Error_Msg_N ("condition is always True?", Cond);
3519 Error_Msg_N ("condition is always False?", Cond);
3525 end Warn_On_Known_Condition;
3527 ---------------------------------------
3528 -- Warn_On_Modified_As_Out_Parameter --
3529 ---------------------------------------
3531 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3534 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3535 or else Warn_On_All_Unread_Out_Parameters;
3536 end Warn_On_Modified_As_Out_Parameter;
3538 ------------------------------
3539 -- Warn_On_Suspicious_Index --
3540 ------------------------------
3542 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3545 -- Set to lower bound for a suspicious type
3548 -- Entity for array reference
3553 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3554 -- Tests to see if Typ is a type for which we may have a suspicious
3555 -- index, namely an unconstrained array type, whose lower bound is
3556 -- either zero or one. If so, True is returned, and Low_Bound is set
3557 -- to this lower bound. If not, False is returned, and Low_Bound is
3558 -- undefined on return.
3560 -- For now, we limit this to standard string types, so any other
3561 -- unconstrained types return False. We may change our minds on this
3562 -- later on, but strings seem the most important case.
3564 procedure Test_Suspicious_Index;
3565 -- Test if index is of suspicious type and if so, generate warning
3567 ------------------------
3568 -- Is_Suspicious_Type --
3569 ------------------------
3571 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3575 if Is_Array_Type (Typ)
3576 and then not Is_Constrained (Typ)
3577 and then Number_Dimensions (Typ) = 1
3578 and then (Root_Type (Typ) = Standard_String
3580 Root_Type (Typ) = Standard_Wide_String
3582 Root_Type (Typ) = Standard_Wide_Wide_String)
3583 and then not Has_Warnings_Off (Typ)
3585 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3587 if Compile_Time_Known_Value (LB) then
3588 Low_Bound := Expr_Value (LB);
3589 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3594 end Is_Suspicious_Type;
3596 ---------------------------
3597 -- Test_Suspicious_Index --
3598 ---------------------------
3600 procedure Test_Suspicious_Index is
3602 function Length_Reference (N : Node_Id) return Boolean;
3603 -- Check if node N is of the form Name'Length
3606 -- Generate first warning line
3608 ----------------------
3609 -- Length_Reference --
3610 ----------------------
3612 function Length_Reference (N : Node_Id) return Boolean is
3613 R : constant Node_Id := Original_Node (N);
3616 Nkind (R) = N_Attribute_Reference
3617 and then Attribute_Name (R) = Name_Length
3618 and then Is_Entity_Name (Prefix (R))
3619 and then Entity (Prefix (R)) = Ent;
3620 end Length_Reference;
3628 Error_Msg_Uint_1 := Low_Bound;
3629 Error_Msg_FE ("?index for& may assume lower bound of^", X, Ent);
3632 -- Start of processing for Test_Suspicious_Index
3635 -- Nothing to do if subscript does not come from source (we don't
3636 -- want to give garbage warnings on compiler expanded code, e.g. the
3637 -- loops generated for slice assignments. Such junk warnings would
3638 -- be placed on source constructs with no subscript in sight!)
3640 if not Comes_From_Source (Original_Node (X)) then
3644 -- Case where subscript is a constant integer
3646 if Nkind (X) = N_Integer_Literal then
3649 -- Case where original form of subscript is an integer literal
3651 if Nkind (Original_Node (X)) = N_Integer_Literal then
3652 if Intval (X) = Low_Bound then
3653 Error_Msg_FE -- CODEFIX
3654 ("\suggested replacement: `&''First`", X, Ent);
3656 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3657 Error_Msg_FE -- CODEFIX
3658 ("\suggested replacement: `&''First + ^`", X, Ent);
3662 -- Case where original form of subscript is more complex
3665 -- Build string X'First - 1 + expression where the expression
3666 -- is the original subscript. If the expression starts with "1
3667 -- + ", then the "- 1 + 1" is elided.
3669 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3670 Error_Msg_Strlen := 13;
3673 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3674 Tref : constant Source_Buffer_Ptr :=
3675 Source_Text (Get_Source_File_Index (Sref));
3676 -- Tref (Sref) is used to scan the subscript
3679 -- Parentheses counter when scanning subscript
3682 -- Tref (Sref) points to start of subscript
3684 -- Elide - 1 if subscript starts with 1 +
3686 if Tref (Sref .. Sref + 2) = "1 +" then
3687 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3690 elsif Tref (Sref .. Sref + 1) = "1+" then
3691 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3695 -- Now we will copy the subscript to the string buffer
3699 -- Count parens, exit if terminating right paren. Note
3700 -- check to ignore paren appearing as character literal.
3702 if Tref (Sref + 1) = '''
3704 Tref (Sref - 1) = '''
3708 if Tref (Sref) = '(' then
3710 elsif Tref (Sref) = ')' then
3716 -- Done if terminating double dot (slice case)
3719 and then (Tref (Sref .. Sref + 1) = ".."
3721 Tref (Sref .. Sref + 2) = " ..");
3723 -- Quit if we have hit EOF character, something wrong
3725 if Tref (Sref) = EOF then
3729 -- String literals are too much of a pain to handle
3731 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3735 -- If we have a 'Range reference, then this is a case
3736 -- where we cannot easily give a replacement. Don't try!
3738 if Tref (Sref .. Sref + 4) = "range"
3739 and then Tref (Sref - 1) < 'A'
3740 and then Tref (Sref + 5) < 'A'
3745 -- Else store next character
3747 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3748 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3751 -- If we get more than 40 characters then the expression
3752 -- is too long to copy, or something has gone wrong. In
3753 -- either case, just skip the attempt at a suggested fix.
3755 if Error_Msg_Strlen > 40 then
3761 -- Replacement subscript is now in string buffer
3763 Error_Msg_FE -- CODEFIX
3764 ("\suggested replacement: `&~`", Original_Node (X), Ent);
3767 -- Case where subscript is of the form X'Length
3769 elsif Length_Reference (X) then
3771 Error_Msg_Node_2 := Ent;
3773 ("\suggest replacement of `&''Length` by `&''Last`",
3776 -- Case where subscript is of the form X'Length - expression
3778 elsif Nkind (X) = N_Op_Subtract
3779 and then Length_Reference (Left_Opnd (X))
3782 Error_Msg_Node_2 := Ent;
3784 ("\suggest replacement of `&''Length` by `&''Last`",
3785 Left_Opnd (X), Ent);
3787 end Test_Suspicious_Index;
3789 -- Start of processing for Warn_On_Suspicious_Index
3792 -- Only process if warnings activated
3794 if Warn_On_Assumed_Low_Bound then
3796 -- Test if array is simple entity name
3798 if Is_Entity_Name (Name) then
3800 -- Test if array is parameter of unconstrained string type
3802 Ent := Entity (Name);
3806 and then Is_Suspicious_Type (Typ)
3807 and then not Low_Bound_Tested (Ent)
3809 Test_Suspicious_Index;
3813 end Warn_On_Suspicious_Index;
3815 --------------------------------------
3816 -- Warn_On_Unassigned_Out_Parameter --
3817 --------------------------------------
3819 procedure Warn_On_Unassigned_Out_Parameter
3820 (Return_Node : Node_Id;
3821 Scope_Id : Entity_Id)
3827 -- Ignore if procedure or return statement does not come from source
3829 if not Comes_From_Source (Scope_Id)
3830 or else not Comes_From_Source (Return_Node)
3835 -- Loop through formals
3837 Form := First_Formal (Scope_Id);
3838 while Present (Form) loop
3840 -- We are only interested in OUT parameters that come from source
3841 -- and are never set in the source, and furthermore only in scalars
3842 -- since non-scalars generate too many false positives.
3844 if Ekind (Form) = E_Out_Parameter
3845 and then Never_Set_In_Source_Check_Spec (Form)
3846 and then Is_Scalar_Type (Etype (Form))
3847 and then not Present (Unset_Reference (Form))
3849 -- Before we issue the warning, an add ad hoc defence against the
3850 -- most common case of false positives with this warning which is
3851 -- the case where there is a Boolean OUT parameter that has been
3852 -- set, and whose meaning is "ignore the values of the other
3853 -- parameters". We can't of course reliably tell this case at
3854 -- compile time, but the following test kills a lot of false
3855 -- positives, without generating a significant number of false
3856 -- negatives (missed real warnings).
3858 Form2 := First_Formal (Scope_Id);
3859 while Present (Form2) loop
3860 if Ekind (Form2) = E_Out_Parameter
3861 and then Root_Type (Etype (Form2)) = Standard_Boolean
3862 and then not Never_Set_In_Source_Check_Spec (Form2)
3867 Next_Formal (Form2);
3870 -- Here all conditions are met, record possible unset reference
3872 Set_Unset_Reference (Form, Return_Node);
3877 end Warn_On_Unassigned_Out_Parameter;
3879 ---------------------------------
3880 -- Warn_On_Unreferenced_Entity --
3881 ---------------------------------
3883 procedure Warn_On_Unreferenced_Entity
3884 (Spec_E : Entity_Id;
3885 Body_E : Entity_Id := Empty)
3887 E : Entity_Id := Spec_E;
3890 if not Referenced_Check_Spec (E)
3891 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3892 and then not Warnings_Off_Check_Spec (E)
3897 -- Case of variable that is assigned but not read. We suppress
3898 -- the message if the variable is volatile, has an address
3899 -- clause, is aliased, or is a renaming, or is imported.
3901 if Referenced_As_LHS_Check_Spec (E)
3902 and then No (Address_Clause (E))
3903 and then not Is_Volatile (E)
3905 if Warn_On_Modified_Unread
3906 and then not Is_Imported (E)
3907 and then not Is_Aliased (E)
3908 and then No (Renamed_Object (E))
3910 if not Has_Pragma_Unmodified_Check_Spec (E) then
3911 Error_Msg_N -- CODEFIX
3912 ("?variable & is assigned but never read!", E);
3915 Set_Last_Assignment (E, Empty);
3918 -- Normal case of neither assigned nor read (exclude variables
3919 -- referenced as out parameters, since we already generated
3920 -- appropriate warnings at the call point in this case).
3922 elsif not Referenced_As_Out_Parameter (E) then
3924 -- We suppress the message for types for which a valid
3925 -- pragma Unreferenced_Objects has been given, otherwise
3926 -- we go ahead and give the message.
3928 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3930 -- Distinguish renamed case in message
3932 if Present (Renamed_Object (E))
3933 and then Comes_From_Source (Renamed_Object (E))
3936 ("?renamed variable & is not referenced!", E);
3939 ("?variable & is not referenced!", E);
3945 if Present (Renamed_Object (E))
3946 and then Comes_From_Source (Renamed_Object (E))
3949 ("?renamed constant & is not referenced!", E);
3951 Error_Msg_N ("?constant & is not referenced!", E);
3954 when E_In_Parameter |
3955 E_In_Out_Parameter =>
3957 -- Do not emit message for formals of a renaming, because
3958 -- they are never referenced explicitly.
3960 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E))))
3961 /= N_Subprogram_Renaming_Declaration
3963 -- Suppress this message for an IN OUT parameter of a
3964 -- non-scalar type, since it is normal to have only an
3965 -- assignment in such a case.
3967 if Ekind (E) = E_In_Parameter
3968 or else not Referenced_As_LHS_Check_Spec (E)
3969 or else Is_Scalar_Type (Etype (E))
3971 if Present (Body_E) then
3975 if not Is_Trivial_Subprogram (Scope (E)) then
3977 ("?formal parameter & is not referenced!",
3983 when E_Out_Parameter =>
3986 when E_Discriminant =>
3987 Error_Msg_N ("?discriminant & is not referenced!", E);
3989 when E_Named_Integer |
3991 Error_Msg_N ("?named number & is not referenced!", E);
3993 when Formal_Object_Kind =>
3994 Error_Msg_N ("?formal object & is not referenced!", E);
3996 when E_Enumeration_Literal =>
3997 Error_Msg_N ("?literal & is not referenced!", E);
4000 Error_Msg_N ("?function & is not referenced!", E);
4003 Error_Msg_N ("?procedure & is not referenced!", E);
4006 Error_Msg_N ("?package & is not referenced!", E);
4009 Error_Msg_N ("?exception & is not referenced!", E);
4012 Error_Msg_N ("?label & is not referenced!", E);
4014 when E_Generic_Procedure =>
4015 Error_Msg_N -- CODEFIX
4016 ("?generic procedure & is never instantiated!", E);
4018 when E_Generic_Function =>
4019 Error_Msg_N -- CODEFIX
4020 ("?generic function & is never instantiated!", E);
4023 Error_Msg_N ("?type & is not referenced!", E);
4026 Error_Msg_N ("?& is not referenced!", E);
4029 -- Kill warnings on the entity on which the message has been posted
4031 Set_Warnings_Off (E);
4033 end Warn_On_Unreferenced_Entity;
4035 --------------------------------
4036 -- Warn_On_Useless_Assignment --
4037 --------------------------------
4039 procedure Warn_On_Useless_Assignment
4041 N : Node_Id := Empty)
4046 function Check_Ref (N : Node_Id) return Traverse_Result;
4047 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4048 -- the entity in question is found.
4050 function Test_No_Refs is new Traverse_Func (Check_Ref);
4056 function Check_Ref (N : Node_Id) return Traverse_Result is
4058 -- Check reference to our identifier. We use name equality here
4059 -- because the exception handlers have not yet been analyzed. This
4060 -- is not quite right, but it really does not matter that we fail
4061 -- to output the warning in some obscure cases of name clashes.
4063 if Nkind (N) = N_Identifier
4064 and then Chars (N) = Chars (Ent)
4072 -- Start of processing for Warn_On_Useless_Assignment
4075 -- Check if this is a case we want to warn on, a scalar or access
4076 -- variable with the last assignment field set, with warnings enabled,
4077 -- and which is not imported or exported. We also check that it is OK
4078 -- to capture the value. We are not going to capture any value, but
4079 -- the warning message depends on the same kind of conditions.
4081 if Is_Assignable (Ent)
4082 and then not Is_Return_Object (Ent)
4083 and then Present (Last_Assignment (Ent))
4084 and then not Is_Imported (Ent)
4085 and then not Is_Exported (Ent)
4086 and then Safe_To_Capture_Value (N, Ent)
4087 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
4089 -- Before we issue the message, check covering exception handlers.
4090 -- Search up tree for enclosing statement sequences and handlers.
4092 P := Parent (Last_Assignment (Ent));
4093 while Present (P) loop
4095 -- Something is really wrong if we don't find a handled statement
4096 -- sequence, so just suppress the warning.
4099 Set_Last_Assignment (Ent, Empty);
4102 -- When we hit a package/subprogram body, issue warning and exit
4104 elsif Nkind (P) = N_Subprogram_Body
4105 or else Nkind (P) = N_Package_Body
4107 -- Case of assigned value never referenced
4111 -- Don't give this for OUT and IN OUT formals, since
4112 -- clearly caller may reference the assigned value. Also
4113 -- never give such warnings for internal variables.
4115 if Ekind (Ent) = E_Variable
4116 and then not Is_Internal_Name (Chars (Ent))
4118 if Referenced_As_Out_Parameter (Ent) then
4120 ("?& modified by call, but value never referenced",
4121 Last_Assignment (Ent), Ent);
4124 ("?useless assignment to&, value never referenced!",
4125 Last_Assignment (Ent), Ent);
4129 -- Case of assigned value overwritten
4132 Error_Msg_Sloc := Sloc (N);
4134 if Referenced_As_Out_Parameter (Ent) then
4136 ("?& modified by call, but value overwritten #!",
4137 Last_Assignment (Ent), Ent);
4140 ("?useless assignment to&, value overwritten #!",
4141 Last_Assignment (Ent), Ent);
4145 -- Clear last assignment indication and we are done
4147 Set_Last_Assignment (Ent, Empty);
4150 -- Enclosing handled sequence of statements
4152 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4154 -- Check exception handlers present
4156 if Present (Exception_Handlers (P)) then
4158 -- If we are not at the top level, we regard an inner
4159 -- exception handler as a decisive indicator that we should
4160 -- not generate the warning, since the variable in question
4161 -- may be accessed after an exception in the outer block.
4163 if Nkind (Parent (P)) /= N_Subprogram_Body
4164 and then Nkind (Parent (P)) /= N_Package_Body
4166 Set_Last_Assignment (Ent, Empty);
4169 -- Otherwise we are at the outer level. An exception
4170 -- handler is significant only if it references the
4171 -- variable in question, or if the entity in question
4172 -- is an OUT or IN OUT parameter, which which case
4173 -- the caller can reference it after the exception
4174 -- hanlder completes
4177 if Is_Formal (Ent) then
4178 Set_Last_Assignment (Ent, Empty);
4182 X := First (Exception_Handlers (P));
4183 while Present (X) loop
4184 if Test_No_Refs (X) = Abandon then
4185 Set_Last_Assignment (Ent, Empty);
4199 end Warn_On_Useless_Assignment;
4201 ---------------------------------
4202 -- Warn_On_Useless_Assignments --
4203 ---------------------------------
4205 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4208 if Warn_On_Modified_Unread
4209 and then In_Extended_Main_Source_Unit (E)
4211 Ent := First_Entity (E);
4212 while Present (Ent) loop
4213 Warn_On_Useless_Assignment (Ent);
4217 end Warn_On_Useless_Assignments;
4219 -----------------------------
4220 -- Warnings_Off_Check_Spec --
4221 -----------------------------
4223 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4225 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4227 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4228 -- to mess with flags on both entities.
4230 return Has_Warnings_Off (E)
4232 Has_Warnings_Off (Spec_Entity (E));
4235 return Has_Warnings_Off (E);
4237 end Warnings_Off_Check_Spec;