1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2010, 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 Expression : Node_Id := Empty;
238 -- Set to WHILE or EXIT WHEN condition to be tested
240 Ref : Node_Id := Empty;
241 -- Reference in Expression to variable that might not be modified
242 -- in loop, indicating a possible infinite loop.
244 Var : Entity_Id := Empty;
245 -- Corresponding entity (entity of Ref)
247 Function_Call_Found : Boolean := False;
248 -- True if Find_Var found a function call in the condition
250 procedure Find_Var (N : Node_Id);
251 -- Inspect condition to see if it depends on a single entity reference.
252 -- If so, Ref is set to point to the reference node, and Var is set to
253 -- the referenced Entity.
255 function Has_Indirection (T : Entity_Id) return Boolean;
256 -- If the controlling variable is an access type, or is a record type
257 -- with access components, assume that it is changed indirectly and
258 -- suppress the warning. As a concession to low-level programming, in
259 -- particular within Declib, we also suppress warnings on a record
260 -- type that contains components of type Address or Short_Address.
262 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
263 -- Given an entity name, see if the name appears to have something to
264 -- do with I/O or network stuff, and if so, return True. Used to kill
265 -- some false positives on a heuristic basis that such functions will
266 -- likely have some strange side effect dependencies. A rather funny
267 -- kludge, but warning messages are in the heuristics business.
269 function Test_Ref (N : Node_Id) return Traverse_Result;
270 -- Test for reference to variable in question. Returns Abandon if
271 -- matching reference found. Used in instantiation of No_Ref_Found.
273 function No_Ref_Found is new Traverse_Func (Test_Ref);
274 -- Function to traverse body of procedure. Returns Abandon if matching
281 procedure Find_Var (N : Node_Id) is
283 -- Condition is a direct variable reference
285 if Is_Entity_Name (N) then
289 -- Case of condition is a comparison with compile time known value
291 elsif Nkind (N) in N_Op_Compare then
292 if Compile_Time_Known_Value (Right_Opnd (N)) then
293 Find_Var (Left_Opnd (N));
295 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
296 Find_Var (Right_Opnd (N));
298 -- Ignore any other comparison
304 -- If condition is a negation, check its operand
306 elsif Nkind (N) = N_Op_Not then
307 Find_Var (Right_Opnd (N));
309 -- Case of condition is function call
311 elsif Nkind (N) = N_Function_Call then
313 Function_Call_Found := True;
315 -- Forget it if function name is not entity, who knows what
316 -- we might be calling?
318 if not Is_Entity_Name (Name (N)) then
321 -- Forget it if function name is suspicious. A strange test
322 -- but warning generation is in the heuristics business!
324 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
327 -- Forget it if warnings are suppressed on function entity
329 elsif Has_Warnings_Off (Entity (Name (N))) then
333 -- OK, see if we have one argument
336 PA : constant List_Id := Parameter_Associations (N);
339 -- One argument, so check the argument
342 and then List_Length (PA) = 1
344 if Nkind (First (PA)) = N_Parameter_Association then
345 Find_Var (Explicit_Actual_Parameter (First (PA)));
347 Find_Var (First (PA));
357 -- Any other kind of node is not something we warn for
364 ---------------------
365 -- Has_Indirection --
366 ---------------------
368 function Has_Indirection (T : Entity_Id) return Boolean is
373 if Is_Access_Type (T) then
376 elsif Is_Private_Type (T)
377 and then Present (Full_View (T))
378 and then Is_Access_Type (Full_View (T))
382 elsif Is_Record_Type (T) then
385 elsif Is_Private_Type (T)
386 and then Present (Full_View (T))
387 and then Is_Record_Type (Full_View (T))
389 Rec := Full_View (T);
394 Comp := First_Component (Rec);
395 while Present (Comp) loop
396 if Is_Access_Type (Etype (Comp))
397 or else Is_Descendent_Of_Address (Etype (Comp))
402 Next_Component (Comp);
408 ---------------------------------
409 -- Is_Suspicious_Function_Name --
410 ---------------------------------
412 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
415 function Substring_Present (S : String) return Boolean;
416 -- Returns True if name buffer has given string delimited by non-
417 -- alphabetic characters or by end of string. S is lower case.
419 -----------------------
420 -- Substring_Present --
421 -----------------------
423 function Substring_Present (S : String) return Boolean is
424 Len : constant Natural := S'Length;
427 for J in 1 .. Name_Len - (Len - 1) loop
428 if Name_Buffer (J .. J + (Len - 1)) = S
431 or else Name_Buffer (J - 1) not in 'a' .. 'z')
434 or else Name_Buffer (J + Len) not in 'a' .. 'z')
441 end Substring_Present;
443 -- Start of processing for Is_Suspicious_Function_Name
447 while Present (S) and then S /= Standard_Standard loop
448 Get_Name_String (Chars (S));
450 if Substring_Present ("io")
451 or else Substring_Present ("file")
452 or else Substring_Present ("network")
461 end Is_Suspicious_Function_Name;
467 function Test_Ref (N : Node_Id) return Traverse_Result is
469 -- Waste of time to look at the expression we are testing
471 if N = Expression then
474 -- Direct reference to variable in question
476 elsif Is_Entity_Name (N)
477 and then Present (Entity (N))
478 and then Entity (N) = Var
480 -- If this is an lvalue, then definitely abandon, since
481 -- this could be a direct modification of the variable.
483 if May_Be_Lvalue (N) then
487 -- If we appear in the context of a procedure call, then also
488 -- abandon, since there may be issues of non-visible side
489 -- effects going on in the call.
498 exit when P = Loop_Statement;
500 -- Abandon if at procedure call, or something strange is
501 -- going on (perhaps a node with no parent that should
502 -- have one but does not?) As always, for a warning we
503 -- prefer to just abandon the warning than get into the
504 -- business of complaining about the tree structure here!
506 if No (P) or else Nkind (P) = N_Procedure_Call_Statement then
512 -- Reference to variable renaming variable in question
514 elsif Is_Entity_Name (N)
515 and then Present (Entity (N))
516 and then Ekind (Entity (N)) = E_Variable
517 and then Present (Renamed_Object (Entity (N)))
518 and then Is_Entity_Name (Renamed_Object (Entity (N)))
519 and then Entity (Renamed_Object (Entity (N))) = Var
520 and then May_Be_Lvalue (N)
524 -- Call to subprogram
526 elsif Nkind (N) = N_Procedure_Call_Statement
527 or else Nkind (N) = N_Function_Call
529 -- If subprogram is within the scope of the entity we are dealing
530 -- with as the loop variable, then it could modify this parameter,
531 -- so we abandon in this case. In the case of a subprogram that is
532 -- not an entity we also abandon. The check for no entity being
533 -- present is a defense against previous errors.
535 if not Is_Entity_Name (Name (N))
536 or else No (Entity (Name (N)))
537 or else Scope_Within (Entity (Name (N)), Scope (Var))
542 -- If any of the arguments are of type access to subprogram, then
543 -- we may have funny side effects, so no warning in this case.
548 Actual := First_Actual (N);
549 while Present (Actual) loop
550 if Is_Access_Subprogram_Type (Etype (Actual)) then
553 Next_Actual (Actual);
558 -- Declaration of the variable in question
560 elsif Nkind (N) = N_Object_Declaration
561 and then Defining_Identifier (N) = Var
566 -- All OK, continue scan
571 -- Start of processing for Check_Infinite_Loop_Warning
574 -- Skip processing if debug flag gnatd.w is set
576 if Debug_Flag_Dot_W then
580 -- Deal with Iteration scheme present
583 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
586 if Present (Iter) then
590 if Present (Condition (Iter)) then
592 -- Skip processing for while iteration with conditions actions,
593 -- since they make it too complicated to get the warning right.
595 if Present (Condition_Actions (Iter)) then
599 -- Capture WHILE condition
601 Expression := Condition (Iter);
603 -- For iteration, do not process, since loop will always terminate
605 elsif Present (Loop_Parameter_Specification (Iter)) then
611 -- Check chain of EXIT statements, we only process loops that have a
612 -- single exit condition (either a single EXIT WHEN statement, or a
613 -- WHILE loop not containing any EXIT WHEN statements).
616 Ident : constant Node_Id := Identifier (Loop_Statement);
620 -- If we don't have a proper chain set, ignore call entirely. This
621 -- happens because of previous errors.
623 if No (Entity (Ident))
624 or else Ekind (Entity (Ident)) /= E_Loop
629 -- Otherwise prepare to scan list of EXIT statements
631 Exit_Stmt := First_Exit_Statement (Entity (Ident));
632 while Present (Exit_Stmt) loop
634 -- Check for EXIT WHEN
636 if Present (Condition (Exit_Stmt)) then
638 -- Quit processing if EXIT WHEN in WHILE loop, or more than
639 -- one EXIT WHEN statement present in the loop.
641 if Present (Expression) then
644 -- Otherwise capture condition from EXIT WHEN statement
647 Expression := Condition (Exit_Stmt);
651 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
655 -- Return if no condition to test
657 if No (Expression) then
661 -- Initial conditions met, see if condition is of right form
663 Find_Var (Expression);
665 -- Nothing to do if local variable from source not found. If it's a
666 -- renaming, it is probably renaming something too complicated to deal
670 or else Ekind (Var) /= E_Variable
671 or else Is_Library_Level_Entity (Var)
672 or else not Comes_From_Source (Var)
673 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
677 -- Nothing to do if there is some indirection involved (assume that the
678 -- designated variable might be modified in some way we don't see).
679 -- However, if no function call was found, then we don't care about
680 -- indirections, because the condition must be something like "while X
681 -- /= null loop", so we don't care if X.all is modified in the loop.
683 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
686 -- Same sort of thing for volatile variable, might be modified by
687 -- some other task or by the operating system in some way.
689 elsif Is_Volatile (Var) then
693 -- Filter out case of original statement sequence starting with delay.
694 -- We assume this is a multi-tasking program and that the condition
695 -- is affected by other threads (some kind of busy wait).
698 Fstm : constant Node_Id :=
699 Original_Node (First (Statements (Loop_Statement)));
701 if Nkind (Fstm) = N_Delay_Relative_Statement
702 or else Nkind (Fstm) = N_Delay_Until_Statement
708 -- We have a variable reference of the right form, now we scan the loop
709 -- body to see if it looks like it might not be modified
711 if No_Ref_Found (Loop_Statement) = OK then
713 ("?variable& is not modified in loop body!", Ref, Var);
715 ("\?possible infinite loop!", Ref);
717 end Check_Infinite_Loop_Warning;
719 ----------------------------
720 -- Check_Low_Bound_Tested --
721 ----------------------------
723 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
725 if Comes_From_Source (Expr) then
727 L : constant Node_Id := Left_Opnd (Expr);
728 R : constant Node_Id := Right_Opnd (Expr);
730 if Nkind (L) = N_Attribute_Reference
731 and then Attribute_Name (L) = Name_First
732 and then Is_Entity_Name (Prefix (L))
733 and then Is_Formal (Entity (Prefix (L)))
735 Set_Low_Bound_Tested (Entity (Prefix (L)));
738 if Nkind (R) = N_Attribute_Reference
739 and then Attribute_Name (R) = Name_First
740 and then Is_Entity_Name (Prefix (R))
741 and then Is_Formal (Entity (Prefix (R)))
743 Set_Low_Bound_Tested (Entity (Prefix (R)));
747 end Check_Low_Bound_Tested;
749 ----------------------
750 -- Check_References --
751 ----------------------
753 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
760 Accept_Statement : Node_Id) return Entity_Id;
761 -- For an entry formal entity from an entry declaration, find the
762 -- corresponding body formal from the given accept statement.
764 function Missing_Subunits return Boolean;
765 -- We suppress warnings when there are missing subunits, because this
766 -- may generate too many false positives: entities in a parent may only
767 -- be referenced in one of the subunits. We make an exception for
768 -- subunits that contain no other stubs.
770 procedure Output_Reference_Error (M : String);
771 -- Used to output an error message. Deals with posting the error on the
772 -- body formal in the accept case.
774 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
775 -- This is true if the entity in question is potentially referenceable
776 -- from another unit. This is true for entities in packages that are at
777 -- the library level.
779 function Warnings_Off_E1 return Boolean;
780 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
781 -- or for the base type of E1T.
789 Accept_Statement : Node_Id) return Entity_Id
791 Body_Param : Node_Id;
795 -- Loop to find matching parameter in accept statement
797 Body_Param := First (Parameter_Specifications (Accept_Statement));
798 while Present (Body_Param) loop
799 Body_E := Defining_Identifier (Body_Param);
801 if Chars (Body_E) = Chars (E) then
808 -- Should never fall through, should always find a match
813 ----------------------
814 -- Missing_Subunits --
815 ----------------------
817 function Missing_Subunits return Boolean is
821 if not Unloaded_Subunits then
823 -- Normal compilation, all subunits are present
827 elsif E /= Main_Unit_Entity then
829 -- No warnings on a stub that is not the main unit
833 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
834 D := First (Declarations (Unit_Declaration_Node (E)));
835 while Present (D) loop
837 -- No warnings if the proper body contains nested stubs
839 if Nkind (D) in N_Body_Stub then
849 -- Missing stubs elsewhere
853 end Missing_Subunits;
855 ----------------------------
856 -- Output_Reference_Error --
857 ----------------------------
859 procedure Output_Reference_Error (M : String) is
861 -- Never issue messages for internal names, nor for renamings
863 if Is_Internal_Name (Chars (E1))
864 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
869 -- Don't output message for IN OUT formal unless we have the warning
870 -- flag specifically set. It is a bit odd to distinguish IN OUT
871 -- formals from other cases. This distinction is historical in
872 -- nature. Warnings for IN OUT formals were added fairly late.
874 if Ekind (E1) = E_In_Out_Parameter
875 and then not Check_Unreferenced_Formals
880 -- Other than accept case, post error on defining identifier
885 -- Accept case, find body formal to post the message
888 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
891 end Output_Reference_Error;
893 ----------------------------
894 -- Publicly_Referenceable --
895 ----------------------------
897 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
902 -- A formal parameter is never referenceable outside the body of its
903 -- subprogram or entry.
905 if Is_Formal (Ent) then
909 -- Examine parents to look for a library level package spec. But if
910 -- we find a body or block or other similar construct along the way,
911 -- we cannot be referenced.
918 -- If we get to top of tree, then publicly referenceable
923 -- If we reach a generic package declaration, then always
924 -- consider this referenceable, since any instantiation will
925 -- have access to the entities in the generic package. Note
926 -- that the package itself may not be instantiated, but then
927 -- we will get a warning for the package entity.
929 -- Note that generic formal parameters are themselves not
930 -- publicly referenceable in an instance, and warnings on them
933 when N_Generic_Package_Declaration =>
935 not Is_List_Member (Prev)
936 or else List_Containing (Prev)
937 /= Generic_Formal_Declarations (P);
939 -- Similarly, the generic formals of a generic subprogram are
942 when N_Generic_Subprogram_Declaration =>
943 if Is_List_Member (Prev)
944 and then List_Containing (Prev) =
945 Generic_Formal_Declarations (P)
952 -- If we reach a subprogram body, entity is not referenceable
953 -- unless it is the defining entity of the body. This will
954 -- happen, e.g. when a function is an attribute renaming that
955 -- is rewritten as a body.
957 when N_Subprogram_Body =>
958 if Ent /= Defining_Entity (P) then
964 -- If we reach any other body, definitely not referenceable
966 when N_Package_Body |
974 -- For all other cases, keep looking up tree
981 end Publicly_Referenceable;
983 ---------------------
984 -- Warnings_Off_E1 --
985 ---------------------
987 function Warnings_Off_E1 return Boolean is
989 return Has_Warnings_Off (E1T)
990 or else Has_Warnings_Off (Base_Type (E1T))
991 or else Warnings_Off_Check_Spec (E1);
994 -- Start of processing for Check_References
997 -- No messages if warnings are suppressed, or if we have detected any
998 -- real errors so far (this last check avoids junk messages resulting
999 -- from errors, e.g. a subunit that is not loaded).
1001 if Warning_Mode = Suppress
1002 or else Serious_Errors_Detected /= 0
1007 -- We also skip the messages if any subunits were not loaded (see
1008 -- comment in Sem_Ch10 to understand how this is set, and why it is
1009 -- necessary to suppress the warnings in this case).
1011 if Missing_Subunits then
1015 -- Otherwise loop through entities, looking for suspicious stuff
1017 E1 := First_Entity (E);
1018 while Present (E1) loop
1021 -- We are only interested in source entities. We also don't issue
1022 -- warnings within instances, since the proper place for such
1023 -- warnings is on the template when it is compiled.
1025 if Comes_From_Source (E1)
1026 and then Instantiation_Location (Sloc (E1)) = No_Location
1028 -- We are interested in variables and out/in-out parameters, but
1029 -- we exclude protected types, too complicated to worry about.
1031 if Ekind (E1) = E_Variable
1033 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1034 and then not Is_Protected_Type (Current_Scope))
1036 -- Case of an unassigned variable
1038 -- First gather any Unset_Reference indication for E1. In the
1039 -- case of a parameter, it is the Spec_Entity that is relevant.
1041 if Ekind (E1) = E_Out_Parameter
1042 and then Present (Spec_Entity (E1))
1044 UR := Unset_Reference (Spec_Entity (E1));
1046 UR := Unset_Reference (E1);
1049 -- Special processing for access types
1052 and then Is_Access_Type (E1T)
1054 -- For access types, the only time we made a UR entry was
1055 -- for a dereference, and so we post the appropriate warning
1056 -- here (note that the dereference may not be explicit in
1057 -- the source, for example in the case of a dispatching call
1058 -- with an anonymous access controlling formal, or of an
1059 -- assignment of a pointer involving discriminant check on
1060 -- the designated object).
1062 if not Warnings_Off_E1 then
1063 Error_Msg_NE ("?& may be null!", UR, E1);
1068 -- Case of variable that could be a constant. Note that we
1069 -- never signal such messages for generic package entities,
1070 -- since a given instance could have modifications outside
1073 elsif Warn_On_Constant
1074 and then (Ekind (E1) = E_Variable
1075 and then Has_Initial_Value (E1))
1076 and then Never_Set_In_Source_Check_Spec (E1)
1077 and then not Address_Taken (E1)
1078 and then not Generic_Package_Spec_Entity (E1)
1080 -- A special case, if this variable is volatile and not
1081 -- imported, it is not helpful to tell the programmer
1082 -- to mark the variable as constant, since this would be
1083 -- illegal by virtue of RM C.6(13).
1085 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1086 and then not Is_Imported (E1)
1089 ("?& is not modified, volatile has no effect!", E1);
1091 -- Another special case, Exception_Occurrence, this catches
1092 -- the case of exception choice (and a bit more too, but not
1093 -- worth doing more investigation here).
1095 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1098 -- Here we give the warning if referenced and no pragma
1099 -- Unreferenced or Unmodified is present.
1104 if Ekind (E1) = E_Variable then
1105 if Referenced_Check_Spec (E1)
1106 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1107 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1109 if not Warnings_Off_E1 then
1110 Error_Msg_N -- CODEFIX
1111 ("?& is not modified, "
1112 & "could be declared constant!",
1119 -- Other cases of a variable or parameter never set in source
1121 elsif Never_Set_In_Source_Check_Spec (E1)
1123 -- No warning if warning for this case turned off
1125 and then Warn_On_No_Value_Assigned
1127 -- No warning if address taken somewhere
1129 and then not Address_Taken (E1)
1131 -- No warning if explicit initial value
1133 and then not Has_Initial_Value (E1)
1135 -- No warning for generic package spec entities, since we
1136 -- might set them in a child unit or something like that
1138 and then not Generic_Package_Spec_Entity (E1)
1140 -- No warning if fully initialized type, except that for
1141 -- this purpose we do not consider access types to qualify
1142 -- as fully initialized types (relying on an access type
1143 -- variable being null when it is never set is a bit odd!)
1145 -- Also we generate warning for an out parameter that is
1146 -- never referenced, since again it seems odd to rely on
1147 -- default initialization to set an out parameter value.
1149 and then (Is_Access_Type (E1T)
1150 or else Ekind (E1) = E_Out_Parameter
1151 or else not Is_Fully_Initialized_Type (E1T))
1153 -- Do not output complaint about never being assigned a
1154 -- value if a pragma Unmodified applies to the variable
1155 -- we are examining, or if it is a parameter, if there is
1156 -- a pragma Unreferenced for the corresponding spec, or
1157 -- if the type is marked as having unreferenced objects.
1158 -- The last is a little peculiar, but better too few than
1159 -- too many warnings in this situation.
1161 if Has_Pragma_Unreferenced_Objects (E1T)
1162 or else Has_Pragma_Unmodified_Check_Spec (E1)
1166 -- IN OUT parameter case where parameter is referenced. We
1167 -- separate this out, since this is the case where we delay
1168 -- output of the warning until more information is available
1169 -- (about use in an instantiation or address being taken).
1171 elsif Ekind (E1) = E_In_Out_Parameter
1172 and then Referenced_Check_Spec (E1)
1174 -- Suppress warning if private type, and the procedure
1175 -- has a separate declaration in a different unit. This
1176 -- is the case where the client of a package sees only
1177 -- the private type, and it may be quite reasonable
1178 -- for the logical view to be IN OUT, even if the
1179 -- implementation ends up using access types or some
1180 -- other method to achieve the local effect of a
1181 -- modification. On the other hand if the spec and body
1182 -- are in the same unit, we are in the package body and
1183 -- there we have less excuse for a junk IN OUT parameter.
1185 if Has_Private_Declaration (E1T)
1186 and then Present (Spec_Entity (E1))
1187 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1191 -- Suppress warning for any parameter of a dispatching
1192 -- operation, since it is quite reasonable to have an
1193 -- operation that is overridden, and for some subclasses
1194 -- needs the formal to be IN OUT and for others happens
1195 -- not to assign it.
1197 elsif Is_Dispatching_Operation
1198 (Scope (Goto_Spec_Entity (E1)))
1202 -- Suppress warning if composite type contains any access
1203 -- component, since the logical effect of modifying a
1204 -- parameter may be achieved by modifying a referenced
1207 elsif Is_Composite_Type (E1T)
1208 and then Has_Access_Values (E1T)
1212 -- Suppress warning on formals of an entry body. All
1213 -- references are attached to the formal in the entry
1214 -- declaration, which are marked Is_Entry_Formal.
1216 elsif Ekind (Scope (E1)) = E_Entry
1217 and then not Is_Entry_Formal (E1)
1221 -- OK, looks like warning for an IN OUT parameter that
1222 -- could be IN makes sense, but we delay the output of
1223 -- the warning, pending possibly finding out later on
1224 -- that the associated subprogram is used as a generic
1225 -- actual, or its address/access is taken. In these two
1226 -- cases, we suppress the warning because the context may
1227 -- force use of IN OUT, even if in this particular case
1228 -- the formal is not modified.
1231 In_Out_Warnings.Append (E1);
1234 -- Other cases of formals
1236 elsif Is_Formal (E1) then
1237 if not Is_Trivial_Subprogram (Scope (E1)) then
1238 if Referenced_Check_Spec (E1) then
1239 if not Has_Pragma_Unmodified_Check_Spec (E1)
1240 and then not Warnings_Off_E1
1242 Output_Reference_Error
1243 ("?formal parameter& is read but "
1244 & "never assigned!");
1247 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1248 and then not Warnings_Off_E1
1250 Output_Reference_Error
1251 ("?formal parameter& is not referenced!");
1258 if Referenced (E1) then
1259 if not Has_Unmodified (E1)
1260 and then not Warnings_Off_E1
1262 Output_Reference_Error
1263 ("?variable& is read but never assigned!");
1266 elsif not Has_Unreferenced (E1)
1267 and then not Warnings_Off_E1
1269 Output_Reference_Error -- CODEFIX
1270 ("?variable& is never read and never assigned!");
1273 -- Deal with special case where this variable is hidden
1274 -- by a loop variable.
1276 if Ekind (E1) = E_Variable
1277 and then Present (Hiding_Loop_Variable (E1))
1278 and then not Warnings_Off_E1
1281 ("?for loop implicitly declares loop variable!",
1282 Hiding_Loop_Variable (E1));
1284 Error_Msg_Sloc := Sloc (E1);
1286 ("\?declaration hides & declared#!",
1287 Hiding_Loop_Variable (E1));
1294 -- Check for unset reference
1296 if Warn_On_No_Value_Assigned and then Present (UR) then
1298 -- For other than access type, go back to original node to
1299 -- deal with case where original unset reference has been
1300 -- rewritten during expansion.
1302 -- In some cases, the original node may be a type conversion
1303 -- or qualification, and in this case we want the object
1306 UR := Original_Node (UR);
1307 while Nkind (UR) = N_Type_Conversion
1308 or else Nkind (UR) = N_Qualified_Expression
1310 UR := Expression (UR);
1313 -- Here we issue the warning, all checks completed
1315 -- If we have a return statement, this was a case of an OUT
1316 -- parameter not being set at the time of the return. (Note:
1317 -- it can't be N_Extended_Return_Statement, because those
1318 -- are only for functions, and functions do not allow OUT
1321 if not Is_Trivial_Subprogram (Scope (E1)) then
1322 if Nkind (UR) = N_Simple_Return_Statement
1323 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1325 if not Warnings_Off_E1 then
1327 ("?OUT parameter& not set before return", UR, E1);
1330 -- If the unset reference is a selected component
1331 -- prefix from source, mention the component as well.
1332 -- If the selected component comes from expansion, all
1333 -- we know is that the entity is not fully initialized
1334 -- at the point of the reference. Locate a random
1335 -- uninitialized component to get a better message.
1337 elsif Nkind (Parent (UR)) = N_Selected_Component then
1338 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1340 if not Comes_From_Source (Parent (UR)) then
1345 Comp := First_Entity (E1T);
1346 while Present (Comp) loop
1347 if Ekind (Comp) = E_Component
1348 and then Nkind (Parent (Comp)) =
1349 N_Component_Declaration
1350 and then No (Expression (Parent (Comp)))
1352 Error_Msg_Node_2 := Comp;
1361 -- Issue proper warning. This is a case of referencing
1362 -- a variable before it has been explicitly assigned.
1363 -- For access types, UR was only set for dereferences,
1364 -- so the issue is that the value may be null.
1366 if not Is_Trivial_Subprogram (Scope (E1)) then
1367 if not Warnings_Off_E1 then
1368 if Is_Access_Type (Etype (Parent (UR))) then
1369 Error_Msg_N ("?`&.&` may be null!", UR);
1372 ("?`&.&` may be referenced before "
1373 & "it has a value!", UR);
1378 -- All other cases of unset reference active
1380 elsif not Warnings_Off_E1 then
1382 ("?& may be referenced before it has a value!",
1391 -- Then check for unreferenced entities. Note that we are only
1392 -- interested in entities whose Referenced flag is not set.
1394 if not Referenced_Check_Spec (E1)
1396 -- If Referenced_As_LHS is set, then that's still interesting
1397 -- (potential "assigned but never read" case), but not if we
1398 -- have pragma Unreferenced, which cancels this warning.
1400 and then (not Referenced_As_LHS_Check_Spec (E1)
1401 or else not Has_Unreferenced (E1))
1403 -- Check that warnings on unreferenced entities are enabled
1406 ((Check_Unreferenced and then not Is_Formal (E1))
1408 -- Case of warning on unreferenced formal
1411 (Check_Unreferenced_Formals and then Is_Formal (E1))
1413 -- Case of warning on unread variables modified by an
1414 -- assignment, or an OUT parameter if it is the only one.
1417 (Warn_On_Modified_Unread
1418 and then Referenced_As_LHS_Check_Spec (E1))
1420 -- Case of warning on any unread OUT parameter (note
1421 -- such indications are only set if the appropriate
1422 -- warning options were set, so no need to recheck here.
1425 Referenced_As_Out_Parameter_Check_Spec (E1))
1427 -- All other entities, including local packages that cannot be
1428 -- referenced from elsewhere, including those declared within a
1431 and then (Is_Object (E1)
1435 Ekind (E1) = E_Label
1437 Ekind (E1) = E_Exception
1439 Ekind (E1) = E_Named_Integer
1441 Ekind (E1) = E_Named_Real
1443 Is_Overloadable (E1)
1445 -- Package case, if the main unit is a package spec
1446 -- or generic package spec, then there may be a
1447 -- corresponding body that references this package
1448 -- in some other file. Otherwise we can be sure
1449 -- that there is no other reference.
1452 (Ekind (E1) = E_Package
1454 not Is_Package_Or_Generic_Package
1455 (Cunit_Entity (Current_Sem_Unit))))
1457 -- Exclude instantiations, since there is no reason why every
1458 -- entity in an instantiation should be referenced.
1460 and then Instantiation_Location (Sloc (E1)) = No_Location
1462 -- Exclude formal parameters from bodies if the corresponding
1463 -- spec entity has been referenced in the case where there is
1466 and then not (Is_Formal (E1)
1467 and then Ekind (Scope (E1)) = E_Subprogram_Body
1468 and then Present (Spec_Entity (E1))
1469 and then Referenced (Spec_Entity (E1)))
1471 -- Consider private type referenced if full view is referenced.
1472 -- If there is not full view, this is a generic type on which
1473 -- warnings are also useful.
1476 not (Is_Private_Type (E1)
1477 and then Present (Full_View (E1))
1478 and then Referenced (Full_View (E1)))
1480 -- Don't worry about full view, only about private type
1482 and then not Has_Private_Declaration (E1)
1484 -- Eliminate dispatching operations from consideration, we
1485 -- cannot tell if these are referenced or not in any easy
1486 -- manner (note this also catches Adjust/Finalize/Initialize).
1488 and then not Is_Dispatching_Operation (E1)
1490 -- Check entity that can be publicly referenced (we do not give
1491 -- messages for such entities, since there could be other
1492 -- units, not involved in this compilation, that contain
1493 -- relevant references.
1495 and then not Publicly_Referenceable (E1)
1497 -- Class wide types are marked as source entities, but they are
1498 -- not really source entities, and are always created, so we do
1499 -- not care if they are not referenced.
1501 and then Ekind (E1) /= E_Class_Wide_Type
1503 -- Objects other than parameters of task types are allowed to
1504 -- be non-referenced, since they start up tasks!
1506 and then ((Ekind (E1) /= E_Variable
1507 and then Ekind (E1) /= E_Constant
1508 and then Ekind (E1) /= E_Component)
1509 or else not Is_Task_Type (E1T))
1511 -- For subunits, only place warnings on the main unit itself,
1512 -- since parent units are not completely compiled.
1514 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1515 or else Get_Source_Unit (E1) = Main_Unit)
1517 -- No warning on a return object, because these are often
1518 -- created with a single expression and an implicit return.
1519 -- If the object is a variable there will be a warning
1520 -- indicating that it could be declared constant.
1523 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1525 -- Suppress warnings in internal units if not in -gnatg mode
1526 -- (these would be junk warnings for an applications program,
1527 -- since they refer to problems in internal units).
1530 or else not Is_Internal_File_Name
1531 (Unit_File_Name (Get_Source_Unit (E1)))
1533 -- We do not immediately flag the error. This is because we
1534 -- have not expanded generic bodies yet, and they may have
1535 -- the missing reference. So instead we park the entity on a
1536 -- list, for later processing. However for the case of an
1537 -- accept statement we want to output messages now, since
1538 -- we know we already have all information at hand, and we
1539 -- also want to have separate warnings for each accept
1540 -- statement for the same entry.
1542 if Present (Anod) then
1543 pragma Assert (Is_Formal (E1));
1545 -- The unreferenced entity is E1, but post the warning
1546 -- on the body entity for this accept statement.
1548 if not Warnings_Off_E1 then
1549 Warn_On_Unreferenced_Entity
1550 (E1, Body_Formal (E1, Accept_Statement => Anod));
1553 elsif not Warnings_Off_E1 then
1554 Unreferenced_Entities.Append (E1);
1558 -- Generic units are referenced in the generic body, but if they
1559 -- are not public and never instantiated we want to force a
1560 -- warning on them. We treat them as redundant constructs to
1563 elsif Is_Generic_Subprogram (E1)
1564 and then not Is_Instantiated (E1)
1565 and then not Publicly_Referenceable (E1)
1566 and then Instantiation_Depth (Sloc (E1)) = 0
1567 and then Warn_On_Redundant_Constructs
1569 if not Warnings_Off_E1 then
1570 Unreferenced_Entities.Append (E1);
1572 -- Force warning on entity
1574 Set_Referenced (E1, False);
1579 -- Recurse into nested package or block. Do not recurse into a formal
1580 -- package, because the corresponding body is not analyzed.
1583 if (Is_Package_Or_Generic_Package (E1)
1584 and then Nkind (Parent (E1)) = N_Package_Specification
1586 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1587 /= N_Formal_Package_Declaration)
1589 or else Ekind (E1) = E_Block
1591 Check_References (E1);
1596 end Check_References;
1598 ---------------------------
1599 -- Check_Unset_Reference --
1600 ---------------------------
1602 procedure Check_Unset_Reference (N : Node_Id) is
1603 Typ : constant Entity_Id := Etype (N);
1605 function Is_OK_Fully_Initialized return Boolean;
1606 -- This function returns true if the given node N is fully initialized
1607 -- so that the reference is safe as far as this routine is concerned.
1608 -- Safe generally means that the type of N is a fully initialized type.
1609 -- The one special case is that for access types, which are always fully
1610 -- initialized, we don't consider a dereference OK since it will surely
1611 -- be dereferencing a null value, which won't do.
1613 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1614 -- Used to test indexed or selected component or slice to see if the
1615 -- evaluation of the prefix depends on a dereference, and if so, returns
1616 -- True, in which case we always check the prefix, even if we know that
1617 -- the referenced component is initialized. Pref is the prefix to test.
1619 -----------------------------
1620 -- Is_OK_Fully_Initialized --
1621 -----------------------------
1623 function Is_OK_Fully_Initialized return Boolean is
1625 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1628 return Is_Fully_Initialized_Type (Typ);
1630 end Is_OK_Fully_Initialized;
1632 ----------------------------
1633 -- Prefix_Has_Dereference --
1634 ----------------------------
1636 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1638 -- If prefix is of an access type, it certainly needs a dereference
1640 if Is_Access_Type (Etype (Pref)) then
1643 -- If prefix is explicit dereference, that's a dereference for sure
1645 elsif Nkind (Pref) = N_Explicit_Dereference then
1648 -- If prefix is itself a component reference or slice check prefix
1650 elsif Nkind (Pref) = N_Slice
1651 or else Nkind (Pref) = N_Indexed_Component
1652 or else Nkind (Pref) = N_Selected_Component
1654 return Prefix_Has_Dereference (Prefix (Pref));
1656 -- All other cases do not involve a dereference
1661 end Prefix_Has_Dereference;
1663 -- Start of processing for Check_Unset_Reference
1666 -- Nothing to do if warnings suppressed
1668 if Warning_Mode = Suppress then
1672 -- Ignore reference unless it comes from source. Almost always if we
1673 -- have a reference from generated code, it is bogus (e.g. calls to init
1674 -- procs to set default discriminant values).
1676 if not Comes_From_Source (N) then
1680 -- Otherwise see what kind of node we have. If the entity already has an
1681 -- unset reference, it is not necessarily the earliest in the text,
1682 -- because resolution of the prefix of selected components is completed
1683 -- before the resolution of the selected component itself. As a result,
1684 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1685 -- in right-to-left order. If there is already an unset reference, we
1686 -- check whether N is earlier before proceeding.
1690 -- For identifier or expanded name, examine the entity involved
1692 when N_Identifier | N_Expanded_Name =>
1694 E : constant Entity_Id := Entity (N);
1697 if (Ekind (E) = E_Variable
1699 Ekind (E) = E_Out_Parameter)
1700 and then Never_Set_In_Source_Check_Spec (E)
1701 and then not Has_Initial_Value (E)
1702 and then (No (Unset_Reference (E))
1704 Earlier_In_Extended_Unit
1705 (Sloc (N), Sloc (Unset_Reference (E))))
1706 and then not Has_Pragma_Unmodified_Check_Spec (E)
1707 and then not Warnings_Off_Check_Spec (E)
1709 -- We may have an unset reference. The first test is whether
1710 -- this is an access to a discriminant of a record or a
1711 -- component with default initialization. Both of these
1712 -- cases can be ignored, since the actual object that is
1713 -- referenced is definitely initialized. Note that this
1714 -- covers the case of reading discriminants of an OUT
1715 -- parameter, which is OK even in Ada 83.
1717 -- Note that we are only interested in a direct reference to
1718 -- a record component here. If the reference is through an
1719 -- access type, then the access object is being referenced,
1720 -- not the record, and still deserves an unset reference.
1722 if Nkind (Parent (N)) = N_Selected_Component
1723 and not Is_Access_Type (Typ)
1726 ES : constant Entity_Id :=
1727 Entity (Selector_Name (Parent (N)));
1729 if Ekind (ES) = E_Discriminant
1731 (Present (Declaration_Node (ES))
1733 Present (Expression (Declaration_Node (ES))))
1740 -- Exclude fully initialized types
1742 if Is_OK_Fully_Initialized then
1746 -- Here we have a potential unset reference. But before we
1747 -- get worried about it, we have to make sure that the
1748 -- entity declaration is in the same procedure as the
1749 -- reference, since if they are in separate procedures, then
1750 -- we have no idea about sequential execution.
1752 -- The tests in the loop below catch all such cases, but do
1753 -- allow the reference to appear in a loop, block, or
1754 -- package spec that is nested within the declaring scope.
1755 -- As always, it is possible to construct cases where the
1756 -- warning is wrong, that is why it is a warning!
1758 Potential_Unset_Reference : declare
1760 SE : constant Entity_Id := Scope (E);
1762 function Within_Postcondition return Boolean;
1763 -- Returns True iff N is within a Precondition
1765 --------------------------
1766 -- Within_Postcondition --
1767 --------------------------
1769 function Within_Postcondition return Boolean is
1774 while Present (Nod) loop
1775 if Nkind (Nod) = N_Pragma
1776 and then Pragma_Name (Nod) = Name_Postcondition
1781 Nod := Parent (Nod);
1785 end Within_Postcondition;
1787 -- Start of processing for Potential_Unset_Reference
1790 SR := Current_Scope;
1792 if SR = Standard_Standard
1793 or else Is_Subprogram (SR)
1794 or else Is_Concurrent_Body (SR)
1795 or else Is_Concurrent_Type (SR)
1803 -- Case of reference has an access type. This is a
1804 -- special case since access types are always set to null
1805 -- so cannot be truly uninitialized, but we still want to
1806 -- warn about cases of obvious null dereference.
1808 if Is_Access_Type (Typ) then
1809 Access_Type_Case : declare
1813 (N : Node_Id) return Traverse_Result;
1814 -- Process function for instantiation of Traverse
1815 -- below. Checks if N contains reference to E other
1816 -- than a dereference.
1818 function Ref_In (Nod : Node_Id) return Boolean;
1819 -- Determines whether Nod contains a reference to
1820 -- the entity E that is not a dereference.
1827 (N : Node_Id) return Traverse_Result
1830 if Is_Entity_Name (N)
1831 and then Entity (N) = E
1832 and then not Is_Dereferenced (N)
1844 function Ref_In (Nod : Node_Id) return Boolean is
1845 function Traverse is new Traverse_Func (Process);
1847 return Traverse (Nod) = Abandon;
1850 -- Start of processing for Access_Type_Case
1853 -- Don't bother if we are inside an instance, since
1854 -- the compilation of the generic template is where
1855 -- the warning should be issued.
1861 -- Don't bother if this is not the main unit. If we
1862 -- try to give this warning for with'ed units, we
1863 -- get some false positives, since we do not record
1864 -- references in other units.
1866 if not In_Extended_Main_Source_Unit (E)
1868 not In_Extended_Main_Source_Unit (N)
1873 -- We are only interested in dereferences
1875 if not Is_Dereferenced (N) then
1879 -- One more check, don't bother with references
1880 -- that are inside conditional statements or WHILE
1881 -- loops if the condition references the entity in
1882 -- question. This avoids most false positives.
1889 if (Nkind (P) = N_If_Statement
1891 Nkind (P) = N_Elsif_Part)
1892 and then Ref_In (Condition (P))
1896 elsif Nkind (P) = N_Loop_Statement
1897 and then Present (Iteration_Scheme (P))
1899 Ref_In (Condition (Iteration_Scheme (P)))
1904 end Access_Type_Case;
1907 -- One more check, don't bother if we are within a
1908 -- postcondition pragma, since the expression occurs
1909 -- in a place unrelated to the actual test.
1911 if not Within_Postcondition then
1913 -- Here we definitely have a case for giving a warning
1914 -- for a reference to an unset value. But we don't
1915 -- give the warning now. Instead set Unset_Reference
1916 -- in the identifier involved. The reason for this is
1917 -- that if we find the variable is never ever assigned
1918 -- a value then that warning is more important and
1919 -- there is no point in giving the reference warning.
1921 -- If this is an identifier, set the field directly
1923 if Nkind (N) = N_Identifier then
1924 Set_Unset_Reference (E, N);
1926 -- Otherwise it is an expanded name, so set the field
1927 -- of the actual identifier for the reference.
1930 Set_Unset_Reference (E, Selector_Name (N));
1933 end Potential_Unset_Reference;
1937 -- Indexed component or slice
1939 when N_Indexed_Component | N_Slice =>
1941 -- If prefix does not involve dereferencing an access type, then
1942 -- we know we are OK if the component type is fully initialized,
1943 -- since the component will have been set as part of the default
1946 if not Prefix_Has_Dereference (Prefix (N))
1947 and then Is_OK_Fully_Initialized
1951 -- Look at prefix in access type case, or if the component is not
1952 -- fully initialized.
1955 Check_Unset_Reference (Prefix (N));
1960 when N_Selected_Component =>
1962 Pref : constant Node_Id := Prefix (N);
1963 Ent : constant Entity_Id := Entity (Selector_Name (N));
1966 -- If prefix involves dereferencing an access type, always
1967 -- check the prefix, since the issue then is whether this
1968 -- access value is null.
1970 if Prefix_Has_Dereference (Pref) then
1973 -- Always go to prefix if no selector entity is set. Can this
1974 -- happen in the normal case? Not clear, but it definitely can
1975 -- happen in error cases.
1980 -- For a record component, check some cases where we have
1981 -- reasonable cause to consider that the component is known to
1982 -- be or probably is initialized. In this case, we don't care
1983 -- if the prefix itself was explicitly initialized.
1985 -- Discriminants are always considered initialized
1987 elsif Ekind (Ent) = E_Discriminant then
1990 -- An explicitly initialized component is certainly initialized
1992 elsif Nkind (Parent (Ent)) = N_Component_Declaration
1993 and then Present (Expression (Parent (Ent)))
1997 -- A fully initialized component is initialized
1999 elsif Is_OK_Fully_Initialized then
2003 -- If none of those cases apply, check the record type prefix
2005 Check_Unset_Reference (Pref);
2008 -- For type conversions or qualifications examine the expression
2010 when N_Type_Conversion | N_Qualified_Expression =>
2011 Check_Unset_Reference (Expression (N));
2013 -- For explicit dereference, always check prefix, which will generate
2014 -- an unset reference (since this is a case of dereferencing null).
2016 when N_Explicit_Dereference =>
2017 Check_Unset_Reference (Prefix (N));
2019 -- All other cases are not cases of an unset reference
2025 end Check_Unset_Reference;
2027 ------------------------
2028 -- Check_Unused_Withs --
2029 ------------------------
2031 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2037 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2038 -- This is needed for checking the special renaming case
2040 procedure Check_One_Unit (Unit : Unit_Number_Type);
2041 -- Subsidiary procedure, performs checks for specified unit
2043 --------------------
2044 -- Check_One_Unit --
2045 --------------------
2047 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2048 Is_Visible_Renaming : Boolean := False;
2051 procedure Check_Inner_Package (Pack : Entity_Id);
2052 -- Pack is a package local to a unit in a with_clause. Both the unit
2053 -- and Pack are referenced. If none of the entities in Pack are
2054 -- referenced, then the only occurrence of Pack is in a USE clause
2055 -- or a pragma, and a warning is worthwhile as well.
2057 function Check_System_Aux return Boolean;
2058 -- Before giving a warning on a with_clause for System, check whether
2059 -- a system extension is present.
2061 function Find_Package_Renaming
2063 L : Entity_Id) return Entity_Id;
2064 -- The only reference to a context unit may be in a renaming
2065 -- declaration. If this renaming declares a visible entity, do not
2066 -- warn that the context clause could be moved to the body, because
2067 -- the renaming may be intended to re-export the unit.
2069 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2070 -- This function determines if a package has any visible entities.
2071 -- True is returned if there is at least one declared visible entity,
2072 -- otherwise False is returned (e.g. case of only pragmas present).
2074 -------------------------
2075 -- Check_Inner_Package --
2076 -------------------------
2078 procedure Check_Inner_Package (Pack : Entity_Id) is
2080 Un : constant Node_Id := Sinfo.Unit (Cnode);
2082 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2083 -- If N is a use_clause for Pack, emit warning
2085 procedure Check_Use_Clauses is new
2086 Traverse_Proc (Check_Use_Clause);
2088 ----------------------
2089 -- Check_Use_Clause --
2090 ----------------------
2092 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2096 if Nkind (N) = N_Use_Package_Clause then
2097 Nam := First (Names (N));
2098 while Present (Nam) loop
2099 if Entity (Nam) = Pack then
2100 Error_Msg_Qual_Level := 1;
2101 Error_Msg_NE -- CODEFIX
2102 ("?no entities of package& are referenced!",
2104 Error_Msg_Qual_Level := 0;
2112 end Check_Use_Clause;
2114 -- Start of processing for Check_Inner_Package
2117 E := First_Entity (Pack);
2118 while Present (E) loop
2119 if Referenced_Check_Spec (E) then
2126 -- No entities of the package are referenced. Check whether the
2127 -- reference to the package itself is a use clause, and if so
2128 -- place a warning on it.
2130 Check_Use_Clauses (Un);
2131 end Check_Inner_Package;
2133 ----------------------
2134 -- Check_System_Aux --
2135 ----------------------
2137 function Check_System_Aux return Boolean is
2141 if Chars (Lunit) = Name_System
2142 and then Scope (Lunit) = Standard_Standard
2143 and then Present_System_Aux
2145 Ent := First_Entity (System_Aux_Id);
2146 while Present (Ent) loop
2147 if Referenced_Check_Spec (Ent) then
2156 end Check_System_Aux;
2158 ---------------------------
2159 -- Find_Package_Renaming --
2160 ---------------------------
2162 function Find_Package_Renaming
2164 L : Entity_Id) return Entity_Id
2170 Is_Visible_Renaming := False;
2172 E1 := First_Entity (P);
2173 while Present (E1) loop
2174 if Ekind (E1) = E_Package
2175 and then Renamed_Object (E1) = L
2177 Is_Visible_Renaming := not Is_Hidden (E1);
2180 elsif Ekind (E1) = E_Package
2181 and then No (Renamed_Object (E1))
2182 and then not Is_Generic_Instance (E1)
2184 R := Find_Package_Renaming (E1, L);
2187 Is_Visible_Renaming := not Is_Hidden (R);
2196 end Find_Package_Renaming;
2198 --------------------------
2199 -- Has_Visible_Entities --
2200 --------------------------
2202 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2206 -- If unit in context is not a package, it is a subprogram that
2207 -- is not called or a generic unit that is not instantiated
2208 -- in the current unit, and warning is appropriate.
2210 if Ekind (P) /= E_Package then
2214 -- If unit comes from a limited_with clause, look for declaration
2215 -- of shadow entities.
2217 if Present (Limited_View (P)) then
2218 E := First_Entity (Limited_View (P));
2220 E := First_Entity (P);
2224 and then E /= First_Private_Entity (P)
2226 if Comes_From_Source (E)
2227 or else Present (Limited_View (P))
2236 end Has_Visible_Entities;
2238 -- Start of processing for Check_One_Unit
2241 Cnode := Cunit (Unit);
2243 -- Only do check in units that are part of the extended main unit.
2244 -- This is actually a necessary restriction, because in the case of
2245 -- subprogram acting as its own specification, there can be with's in
2246 -- subunits that we will not see.
2248 if not In_Extended_Main_Source_Unit (Cnode) then
2251 -- In configurable run time mode, we remove the bodies of non-inlined
2252 -- subprograms, which may lead to spurious warnings, which are
2253 -- clearly undesirable.
2255 elsif Configurable_Run_Time_Mode
2256 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2261 -- Loop through context items in this unit
2263 Item := First (Context_Items (Cnode));
2264 while Present (Item) loop
2265 if Nkind (Item) = N_With_Clause
2266 and then not Implicit_With (Item)
2267 and then In_Extended_Main_Source_Unit (Item)
2269 Lunit := Entity (Name (Item));
2271 -- Check if this unit is referenced (skip the check if this
2272 -- is explicitly marked by a pragma Unreferenced).
2274 if not Referenced (Lunit)
2275 and then not Has_Unreferenced (Lunit)
2277 -- Suppress warnings in internal units if not in -gnatg mode
2278 -- (these would be junk warnings for an application program,
2279 -- since they refer to problems in internal units).
2282 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2284 -- Here we definitely have a non-referenced unit. If it
2285 -- is the special call for a spec unit, then just set the
2286 -- flag to be read later.
2288 if Unit = Spec_Unit then
2289 Set_Unreferenced_In_Spec (Item);
2291 -- Otherwise simple unreferenced message, but skip this
2292 -- if no visible entities, because that is most likely a
2293 -- case where warning would be false positive (e.g. a
2294 -- package with only a linker options pragma and nothing
2295 -- else or a pragma elaborate with a body library task).
2297 elsif Has_Visible_Entities (Entity (Name (Item))) then
2298 Error_Msg_N -- CODEFIX
2299 ("?unit& is not referenced!", Name (Item));
2303 -- If main unit is a renaming of this unit, then we consider
2304 -- the with to be OK (obviously it is needed in this case!)
2305 -- This may be transitive: the unit in the with_clause may
2306 -- itself be a renaming, in which case both it and the main
2307 -- unit rename the same ultimate package.
2309 elsif Present (Renamed_Entity (Munite))
2311 (Renamed_Entity (Munite) = Lunit
2312 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2316 -- If this unit is referenced, and it is a package, we do
2317 -- another test, to see if any of the entities in the package
2318 -- are referenced. If none of the entities are referenced, we
2319 -- still post a warning. This occurs if the only use of the
2320 -- package is in a use clause, or in a package renaming
2321 -- declaration. This check is skipped for packages that are
2322 -- renamed in a spec, since the entities in such a package are
2323 -- visible to clients via the renaming.
2325 elsif Ekind (Lunit) = E_Package
2326 and then not Renamed_In_Spec (Lunit)
2328 -- If Is_Instantiated is set, it means that the package is
2329 -- implicitly instantiated (this is the case of parent
2330 -- instance or an actual for a generic package formal), and
2331 -- this counts as a reference.
2333 if Is_Instantiated (Lunit) then
2336 -- If no entities in package, and there is a pragma
2337 -- Elaborate_Body present, then assume that this with is
2338 -- done for purposes of this elaboration.
2340 elsif No (First_Entity (Lunit))
2341 and then Has_Pragma_Elaborate_Body (Lunit)
2345 -- Otherwise see if any entities have been referenced
2348 if Limited_Present (Item) then
2349 Ent := First_Entity (Limited_View (Lunit));
2351 Ent := First_Entity (Lunit);
2355 -- No more entities, and we did not find one that was
2356 -- referenced. Means we have a definite case of a with
2357 -- none of whose entities was referenced.
2361 -- If in spec, just set the flag
2363 if Unit = Spec_Unit then
2364 Set_No_Entities_Ref_In_Spec (Item);
2366 elsif Check_System_Aux then
2369 -- Else give the warning
2373 Has_Unreferenced (Entity (Name (Item)))
2375 Error_Msg_N -- CODEFIX
2376 ("?no entities of & are referenced!",
2380 -- Look for renamings of this package, and flag
2381 -- them as well. If the original package has
2382 -- warnings off, we suppress the warning on the
2383 -- renaming as well.
2385 Pack := Find_Package_Renaming (Munite, Lunit);
2388 and then not Has_Warnings_Off (Lunit)
2389 and then not Has_Unreferenced (Pack)
2391 Error_Msg_NE -- CODEFIX
2392 ("?no entities of & are referenced!",
2393 Unit_Declaration_Node (Pack),
2400 -- Case of entity being referenced. The reference may
2401 -- come from a limited_with_clause, in which case the
2402 -- limited view of the entity carries the flag.
2404 elsif Referenced_Check_Spec (Ent)
2405 or else Referenced_As_LHS_Check_Spec (Ent)
2406 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2408 (From_With_Type (Ent)
2409 and then Is_Incomplete_Type (Ent)
2410 and then Present (Non_Limited_View (Ent))
2411 and then Referenced (Non_Limited_View (Ent)))
2413 -- This means that the with is indeed fine, in that
2414 -- it is definitely needed somewhere, and we can
2415 -- quit worrying about this one...
2417 -- Except for one little detail: if either of the
2418 -- flags was set during spec processing, this is
2419 -- where we complain that the with could be moved
2420 -- from the spec. If the spec contains a visible
2421 -- renaming of the package, inhibit warning to move
2422 -- with_clause to body.
2424 if Ekind (Munite) = E_Package_Body then
2426 Find_Package_Renaming
2427 (Spec_Entity (Munite), Lunit);
2430 if Unreferenced_In_Spec (Item) then
2431 Error_Msg_N -- CODEFIX
2432 ("?unit& is not referenced in spec!",
2435 elsif No_Entities_Ref_In_Spec (Item) then
2436 Error_Msg_N -- CODEFIX
2437 ("?no entities of & are referenced in spec!",
2441 if Ekind (Ent) = E_Package then
2442 Check_Inner_Package (Ent);
2448 if not Is_Visible_Renaming then
2449 Error_Msg_N -- CODEFIX
2450 ("\?with clause might be moved to body!",
2456 -- Move to next entity to continue search
2464 -- For a generic package, the only interesting kind of
2465 -- reference is an instantiation, since entities cannot be
2466 -- referenced directly.
2468 elsif Is_Generic_Unit (Lunit) then
2470 -- Unit was never instantiated, set flag for case of spec
2471 -- call, or give warning for normal call.
2473 if not Is_Instantiated (Lunit) then
2474 if Unit = Spec_Unit then
2475 Set_Unreferenced_In_Spec (Item);
2477 Error_Msg_N -- CODEFIX
2478 ("?unit& is never instantiated!", Name (Item));
2481 -- If unit was indeed instantiated, make sure that flag is
2482 -- not set showing it was uninstantiated in the spec, and if
2483 -- so, give warning.
2485 elsif Unreferenced_In_Spec (Item) then
2487 ("?unit& is not instantiated in spec!", Name (Item));
2488 Error_Msg_N -- CODEFIX
2489 ("\?with clause can be moved to body!", Name (Item));
2498 -- Start of processing for Check_Unused_Withs
2501 if not Opt.Check_Withs
2502 or else Operating_Mode = Check_Syntax
2507 -- Flag any unused with clauses, but skip this step if we are compiling
2508 -- a subunit on its own, since we do not have enough information to
2509 -- determine whether with's are used. We will get the relevant warnings
2510 -- when we compile the parent. This is the normal style of GNAT
2511 -- compilation in any case.
2513 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2517 -- Process specified units
2519 if Spec_Unit = No_Unit then
2521 -- For main call, check all units
2523 for Unit in Main_Unit .. Last_Unit loop
2524 Check_One_Unit (Unit);
2528 -- For call for spec, check only the spec
2530 Check_One_Unit (Spec_Unit);
2532 end Check_Unused_Withs;
2534 ---------------------------------
2535 -- Generic_Package_Spec_Entity --
2536 ---------------------------------
2538 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2542 if Is_Package_Body_Entity (E) then
2548 if S = Standard_Standard then
2551 elsif Ekind (S) = E_Generic_Package then
2554 elsif Ekind (S) = E_Package then
2562 end Generic_Package_Spec_Entity;
2564 ----------------------
2565 -- Goto_Spec_Entity --
2566 ----------------------
2568 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2571 and then Present (Spec_Entity (E))
2573 return Spec_Entity (E);
2577 end Goto_Spec_Entity;
2579 --------------------------------------
2580 -- Has_Pragma_Unmodified_Check_Spec --
2581 --------------------------------------
2583 function Has_Pragma_Unmodified_Check_Spec
2584 (E : Entity_Id) return Boolean
2587 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2589 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2590 -- to mess with Unmodified flags on both body and spec entities.
2592 return Has_Unmodified (E)
2594 Has_Unmodified (Spec_Entity (E));
2597 return Has_Unmodified (E);
2599 end Has_Pragma_Unmodified_Check_Spec;
2601 ----------------------------------------
2602 -- Has_Pragma_Unreferenced_Check_Spec --
2603 ----------------------------------------
2605 function Has_Pragma_Unreferenced_Check_Spec
2606 (E : Entity_Id) return Boolean
2609 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2611 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2612 -- to mess with flags on both entities.
2614 return Has_Unreferenced (E)
2616 Has_Unreferenced (Spec_Entity (E));
2619 return Has_Unreferenced (E);
2621 end Has_Pragma_Unreferenced_Check_Spec;
2627 procedure Initialize is
2629 Warnings_Off_Pragmas.Init;
2630 Unreferenced_Entities.Init;
2631 In_Out_Warnings.Init;
2634 ------------------------------------
2635 -- Never_Set_In_Source_Check_Spec --
2636 ------------------------------------
2638 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2640 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2641 return Never_Set_In_Source (E)
2643 Never_Set_In_Source (Spec_Entity (E));
2645 return Never_Set_In_Source (E);
2647 end Never_Set_In_Source_Check_Spec;
2649 -------------------------------------
2650 -- Operand_Has_Warnings_Suppressed --
2651 -------------------------------------
2653 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2655 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2656 -- Function used to check one node to see if it is or was originally
2657 -- a reference to an entity for which Warnings are off. If so, Abandon
2658 -- is returned, otherwise OK_Orig is returned to continue the traversal
2659 -- of the original expression.
2661 function Traverse is new Traverse_Func (Check_For_Warnings);
2662 -- Function used to traverse tree looking for warnings
2664 ------------------------
2665 -- Check_For_Warnings --
2666 ------------------------
2668 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2669 R : constant Node_Id := Original_Node (N);
2672 if Nkind (R) in N_Has_Entity
2673 and then Present (Entity (R))
2674 and then Has_Warnings_Off (Entity (R))
2680 end Check_For_Warnings;
2682 -- Start of processing for Operand_Has_Warnings_Suppressed
2685 return Traverse (N) = Abandon;
2687 -- If any exception occurs, then something has gone wrong, and this is
2688 -- only a minor aesthetic issue anyway, so just say we did not find what
2689 -- we are looking for, rather than blow up.
2694 end Operand_Has_Warnings_Suppressed;
2696 -----------------------------------------
2697 -- Output_Non_Modified_In_Out_Warnings --
2698 -----------------------------------------
2700 procedure Output_Non_Modified_In_Out_Warnings is
2702 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2703 -- Given a formal parameter entity E, determines if there is a reason to
2704 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2705 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2706 -- if we have seen the address of the subprogram being taken, or if the
2707 -- subprogram is used as a generic actual (in the latter cases the
2708 -- context may force use of IN OUT, even if the parameter is not
2709 -- modifies for this particular case.
2711 -----------------------
2712 -- No_Warn_On_In_Out --
2713 -----------------------
2715 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2716 S : constant Entity_Id := Scope (E);
2717 SE : constant Entity_Id := Spec_Entity (E);
2720 -- Do not warn if address is taken, since funny business may be going
2721 -- on in treating the parameter indirectly as IN OUT.
2723 if Address_Taken (S)
2724 or else (Present (SE) and then Address_Taken (Scope (SE)))
2728 -- Do not warn if used as a generic actual, since the generic may be
2729 -- what is forcing the use of an "unnecessary" IN OUT.
2731 elsif Used_As_Generic_Actual (S)
2732 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2736 -- Else test warnings off
2738 elsif Warnings_Off_Check_Spec (S) then
2741 -- All tests for suppressing warning failed
2746 end No_Warn_On_In_Out;
2748 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2751 -- Loop through entities for which a warning may be needed
2753 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2755 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2758 -- Suppress warning in specific cases (see details in comments for
2759 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2761 if Has_Pragma_Unmodified_Check_Spec (E1)
2762 or else No_Warn_On_In_Out (E1)
2766 -- Here we generate the warning
2769 -- If -gnatwc is set then output message that we could be IN
2771 if not Is_Trivial_Subprogram (Scope (E1)) then
2772 if Warn_On_Constant then
2774 ("?formal parameter & is not modified!", E1);
2776 ("\?mode could be IN instead of `IN OUT`!", E1);
2778 -- We do not generate warnings for IN OUT parameters
2779 -- unless we have at least -gnatwu. This is deliberately
2780 -- inconsistent with the treatment of variables, but
2781 -- otherwise we get too many unexpected warnings in
2784 elsif Check_Unreferenced then
2786 ("?formal parameter& is read but "
2787 & "never assigned!", E1);
2791 -- Kill any other warnings on this entity, since this is the
2792 -- one that should dominate any other unreferenced warning.
2794 Set_Warnings_Off (E1);
2798 end Output_Non_Modified_In_Out_Warnings;
2800 ----------------------------------------
2801 -- Output_Obsolescent_Entity_Warnings --
2802 ----------------------------------------
2804 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2805 P : constant Node_Id := Parent (N);
2811 -- Do not output message if we are the scope of standard. This means
2812 -- we have a reference from a context clause from when it is originally
2813 -- processed, and that's too early to tell whether it is an obsolescent
2814 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2815 -- sure that we have a later call when the scope is available. This test
2816 -- also eliminates all messages for use clauses, which is fine (we do
2817 -- not want messages for use clauses, since they are always redundant
2818 -- with respect to the associated with clause).
2820 if S = Standard_Standard then
2824 -- Do not output message if we are in scope of an obsolescent package
2828 if Is_Obsolescent (S) then
2833 exit when S = Standard_Standard;
2836 -- Here we will output the message
2838 Error_Msg_Sloc := Sloc (E);
2840 -- Case of with clause
2842 if Nkind (P) = N_With_Clause then
2843 if Ekind (E) = E_Package then
2845 ("?with of obsolescent package& declared#", N, E);
2846 elsif Ekind (E) = E_Procedure then
2848 ("?with of obsolescent procedure& declared#", N, E);
2851 ("?with of obsolescent function& declared#", N, E);
2854 -- If we do not have a with clause, then ignore any reference to an
2855 -- obsolescent package name. We only want to give the one warning of
2856 -- withing the package, not one each time it is used to qualify.
2858 elsif Ekind (E) = E_Package then
2861 -- Procedure call statement
2863 elsif Nkind (P) = N_Procedure_Call_Statement then
2865 ("?call to obsolescent procedure& declared#", N, E);
2869 elsif Nkind (P) = N_Function_Call then
2871 ("?call to obsolescent function& declared#", N, E);
2873 -- Reference to obsolescent type
2875 elsif Is_Type (E) then
2877 ("?reference to obsolescent type& declared#", N, E);
2879 -- Reference to obsolescent component
2881 elsif Ekind_In (E, E_Component, E_Discriminant) then
2883 ("?reference to obsolescent component& declared#", N, E);
2885 -- Reference to obsolescent variable
2887 elsif Ekind (E) = E_Variable then
2889 ("?reference to obsolescent variable& declared#", N, E);
2891 -- Reference to obsolescent constant
2893 elsif Ekind (E) = E_Constant
2894 or else Ekind (E) in Named_Kind
2897 ("?reference to obsolescent constant& declared#", N, E);
2899 -- Reference to obsolescent enumeration literal
2901 elsif Ekind (E) = E_Enumeration_Literal then
2903 ("?reference to obsolescent enumeration literal& declared#", N, E);
2905 -- Generic message for any other case we missed
2909 ("?reference to obsolescent entity& declared#", N, E);
2912 -- Output additional warning if present
2914 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2915 if Obsolescent_Warnings.Table (J).Ent = E then
2916 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2917 Error_Msg_Strlen := Name_Len;
2918 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2919 Error_Msg_N ("\\?~", N);
2923 end Output_Obsolescent_Entity_Warnings;
2925 ----------------------------------
2926 -- Output_Unreferenced_Messages --
2927 ----------------------------------
2929 procedure Output_Unreferenced_Messages is
2931 for J in Unreferenced_Entities.First ..
2932 Unreferenced_Entities.Last
2934 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2936 end Output_Unreferenced_Messages;
2938 -----------------------------------------
2939 -- Output_Unused_Warnings_Off_Warnings --
2940 -----------------------------------------
2942 procedure Output_Unused_Warnings_Off_Warnings is
2944 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2946 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2947 N : Node_Id renames Wentry.N;
2948 E : Node_Id renames Wentry.E;
2951 -- Turn off Warnings_Off, or we won't get the warning!
2953 Set_Warnings_Off (E, False);
2955 -- Nothing to do if pragma was used to suppress a general warning
2957 if Warnings_Off_Used (E) then
2960 -- If pragma was used both in unmodified and unreferenced contexts
2961 -- then that's as good as the general case, no warning.
2963 elsif Warnings_Off_Used_Unmodified (E)
2965 Warnings_Off_Used_Unreferenced (E)
2969 -- Used only in context where Unmodified would have worked
2971 elsif Warnings_Off_Used_Unmodified (E) then
2973 ("?could use Unmodified instead of "
2974 & "Warnings Off for &", Pragma_Identifier (N), E);
2976 -- Used only in context where Unreferenced would have worked
2978 elsif Warnings_Off_Used_Unreferenced (E) then
2980 ("?could use Unreferenced instead of "
2981 & "Warnings Off for &", Pragma_Identifier (N), E);
2987 ("?pragma Warnings Off for & unused, "
2988 & "could be omitted", N, E);
2992 end Output_Unused_Warnings_Off_Warnings;
2994 ---------------------------
2995 -- Referenced_Check_Spec --
2996 ---------------------------
2998 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3000 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3001 return Referenced (E) or else Referenced (Spec_Entity (E));
3003 return Referenced (E);
3005 end Referenced_Check_Spec;
3007 ----------------------------------
3008 -- Referenced_As_LHS_Check_Spec --
3009 ----------------------------------
3011 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3013 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3014 return Referenced_As_LHS (E)
3015 or else Referenced_As_LHS (Spec_Entity (E));
3017 return Referenced_As_LHS (E);
3019 end Referenced_As_LHS_Check_Spec;
3021 --------------------------------------------
3022 -- Referenced_As_Out_Parameter_Check_Spec --
3023 --------------------------------------------
3025 function Referenced_As_Out_Parameter_Check_Spec
3026 (E : Entity_Id) return Boolean
3029 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3030 return Referenced_As_Out_Parameter (E)
3031 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3033 return Referenced_As_Out_Parameter (E);
3035 end Referenced_As_Out_Parameter_Check_Spec;
3037 -----------------------------
3038 -- Warn_On_Known_Condition --
3039 -----------------------------
3041 procedure Warn_On_Known_Condition (C : Node_Id) is
3043 Orig : constant Node_Id := Original_Node (C);
3044 Test_Result : Boolean;
3046 function Is_Known_Branch return Boolean;
3047 -- If the type of the condition is Boolean, the constant value of the
3048 -- condition is a boolean literal. If the type is a derived boolean
3049 -- type, the constant is wrapped in a type conversion of the derived
3050 -- literal. If the value of the condition is not a literal, no warnings
3051 -- can be produced. This function returns True if the result can be
3052 -- determined, and Test_Result is set True/False accordingly. Otherwise
3053 -- False is returned, and Test_Result is unchanged.
3055 procedure Track (N : Node_Id; Loc : Node_Id);
3056 -- Adds continuation warning(s) pointing to reason (assignment or test)
3057 -- for the operand of the conditional having a known value (or at least
3058 -- enough is known about the value to issue the warning). N is the node
3059 -- which is judged to have a known value. Loc is the warning location.
3061 ---------------------
3062 -- Is_Known_Branch --
3063 ---------------------
3065 function Is_Known_Branch return Boolean is
3067 if Etype (C) = Standard_Boolean
3068 and then Is_Entity_Name (C)
3070 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3072 Test_Result := Entity (C) = Standard_True;
3075 elsif Is_Boolean_Type (Etype (C))
3076 and then Nkind (C) = N_Unchecked_Type_Conversion
3077 and then Is_Entity_Name (Expression (C))
3078 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3081 Chars (Entity (Expression (C))) = Chars (Standard_True);
3087 end Is_Known_Branch;
3093 procedure Track (N : Node_Id; Loc : Node_Id) is
3094 Nod : constant Node_Id := Original_Node (N);
3097 if Nkind (Nod) in N_Op_Compare then
3098 Track (Left_Opnd (Nod), Loc);
3099 Track (Right_Opnd (Nod), Loc);
3101 elsif Is_Entity_Name (Nod)
3102 and then Is_Object (Entity (Nod))
3105 CV : constant Node_Id := Current_Value (Entity (Nod));
3108 if Present (CV) then
3109 Error_Msg_Sloc := Sloc (CV);
3111 if Nkind (CV) not in N_Subexpr then
3112 Error_Msg_N ("\\?(see test #)", Loc);
3114 elsif Nkind (Parent (CV)) =
3115 N_Case_Statement_Alternative
3117 Error_Msg_N ("\\?(see case alternative #)", Loc);
3120 Error_Msg_N ("\\?(see assignment #)", Loc);
3127 -- Start of processing for Warn_On_Known_Condition
3130 -- Adjust SCO condition if from source
3133 and then Comes_From_Source (Orig)
3134 and then Is_Known_Branch
3140 Atrue := Test_Result;
3142 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3146 Set_SCO_Condition (Orig, Atrue);
3150 -- Argument replacement in an inlined body can make conditions static.
3151 -- Do not emit warnings in this case.
3153 if In_Inlined_Body then
3157 if Constant_Condition_Warnings
3158 and then Is_Known_Branch
3159 and then Comes_From_Source (Original_Node (C))
3160 and then not In_Instance
3162 -- See if this is in a statement or a declaration
3166 -- If tree is not attached, do not issue warning (this is very
3167 -- peculiar, and probably arises from some other error condition)
3172 -- If we are in a declaration, then no warning, since in practice
3173 -- conditionals in declarations are used for intended tests which
3174 -- may be known at compile time, e.g. things like
3176 -- x : constant Integer := 2 + (Word'Size = 32);
3178 -- And a warning is annoying in such cases
3180 elsif Nkind (P) in N_Declaration
3182 Nkind (P) in N_Later_Decl_Item
3186 -- Don't warn in assert or check pragma, since presumably tests in
3187 -- such a context are very definitely intended, and might well be
3188 -- known at compile time. Note that we have to test the original
3189 -- node, since assert pragmas get rewritten at analysis time.
3191 elsif Nkind (Original_Node (P)) = N_Pragma
3192 and then (Pragma_Name (Original_Node (P)) = Name_Assert
3194 Pragma_Name (Original_Node (P)) = Name_Check)
3199 exit when Is_Statement (P);
3203 -- Here we issue the warning unless some sub-operand has warnings
3204 -- set off, in which case we suppress the warning for the node. If
3205 -- the original expression is an inequality, it has been expanded
3206 -- into a negation, and the value of the original expression is the
3207 -- negation of the equality. If the expression is an entity that
3208 -- appears within a negation, it is clearer to flag the negation
3209 -- itself, and report on its constant value.
3211 if not Operand_Has_Warnings_Suppressed (C) then
3213 True_Branch : Boolean := Test_Result;
3214 Cond : Node_Id := C;
3217 if Present (Parent (C))
3218 and then Nkind (Parent (C)) = N_Op_Not
3220 True_Branch := not True_Branch;
3225 if Is_Entity_Name (Original_Node (C))
3226 and then Nkind (Cond) /= N_Op_Not
3229 ("object & is always True?", Cond, Original_Node (C));
3230 Track (Original_Node (C), Cond);
3233 Error_Msg_N ("condition is always True?", Cond);
3238 Error_Msg_N ("condition is always False?", Cond);
3244 end Warn_On_Known_Condition;
3246 ---------------------------------------
3247 -- Warn_On_Modified_As_Out_Parameter --
3248 ---------------------------------------
3250 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3253 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3254 or else Warn_On_All_Unread_Out_Parameters;
3255 end Warn_On_Modified_As_Out_Parameter;
3257 ---------------------------------
3258 -- Warn_On_Overlapping_Actuals --
3259 ---------------------------------
3261 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3262 Act1, Act2 : Node_Id;
3263 Form1, Form2 : Entity_Id;
3266 if not Warn_On_Overlap then
3270 -- Exclude calls rewritten as enumeration literals
3272 if not Nkind_In (N, N_Function_Call, N_Procedure_Call_Statement) then
3276 -- Exclude calls to library subprograms. Container operations specify
3277 -- safe behavior when source and target coincide.
3279 if Is_Predefined_File_Name
3280 (Unit_File_Name (Get_Source_Unit (Sloc (Subp))))
3285 Form1 := First_Formal (Subp);
3286 Act1 := First_Actual (N);
3287 while Present (Form1) and then Present (Act1) loop
3288 if Ekind (Form1) /= E_In_Parameter then
3289 Form2 := First_Formal (Subp);
3290 Act2 := First_Actual (N);
3291 while Present (Form2) and then Present (Act2) loop
3293 and then Ekind (Form2) /= E_Out_Parameter
3295 (Denotes_Same_Object (Act1, Act2)
3297 Denotes_Same_Prefix (Act1, Act2))
3299 -- Exclude generic types and guard against previous errors.
3302 or else No (Etype (Act1))
3303 or else No (Etype (Act2))
3307 elsif Is_Generic_Type (Etype (Act1))
3309 Is_Generic_Type (Etype (Act2))
3313 -- If the actual is a function call in prefix notation,
3314 -- there is no real overlap.
3316 elsif Nkind (Act2) = N_Function_Call then
3319 -- If type is not by-copy we can assume that the aliasing is
3323 Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3333 -- Find matching actual
3335 Act := First_Actual (N);
3336 Form := First_Formal (Subp);
3337 while Act /= Act2 loop
3342 if Is_Elementary_Type (Etype (Act1))
3343 and then Ekind (Form2) = E_In_Parameter
3345 null; -- no real aliasing.
3347 elsif Is_Elementary_Type (Etype (Act2))
3348 and then Ekind (Form2) = E_In_Parameter
3352 -- If the call was written in prefix notation, and
3353 -- thus its prefix before rewriting was a selected
3354 -- component, count only visible actuals in the call.
3356 elsif Is_Entity_Name (First_Actual (N))
3357 and then Nkind (Original_Node (N)) = Nkind (N)
3358 and then Nkind (Name (Original_Node (N))) =
3359 N_Selected_Component
3361 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3363 Entity (Prefix (Name (Original_Node (N)))) =
3364 Entity (First_Actual (N))
3366 if Act1 = First_Actual (N) then
3368 ("`IN OUT` prefix overlaps with actual for&?",
3372 ("writable actual overlaps with actual for&?",
3377 Error_Msg_Node_2 := Form;
3379 ("writable actual for & overlaps with"
3380 & " actual for&?", Act1, Form1);
3388 Next_Formal (Form2);
3393 Next_Formal (Form1);
3396 end Warn_On_Overlapping_Actuals;
3398 ------------------------------
3399 -- Warn_On_Suspicious_Index --
3400 ------------------------------
3402 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3405 -- Set to lower bound for a suspicious type
3408 -- Entity for array reference
3413 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3414 -- Tests to see if Typ is a type for which we may have a suspicious
3415 -- index, namely an unconstrained array type, whose lower bound is
3416 -- either zero or one. If so, True is returned, and Low_Bound is set
3417 -- to this lower bound. If not, False is returned, and Low_Bound is
3418 -- undefined on return.
3420 -- For now, we limit this to standard string types, so any other
3421 -- unconstrained types return False. We may change our minds on this
3422 -- later on, but strings seem the most important case.
3424 procedure Test_Suspicious_Index;
3425 -- Test if index is of suspicious type and if so, generate warning
3427 ------------------------
3428 -- Is_Suspicious_Type --
3429 ------------------------
3431 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3435 if Is_Array_Type (Typ)
3436 and then not Is_Constrained (Typ)
3437 and then Number_Dimensions (Typ) = 1
3438 and then (Root_Type (Typ) = Standard_String
3440 Root_Type (Typ) = Standard_Wide_String
3442 Root_Type (Typ) = Standard_Wide_Wide_String)
3443 and then not Has_Warnings_Off (Typ)
3445 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3447 if Compile_Time_Known_Value (LB) then
3448 Low_Bound := Expr_Value (LB);
3449 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3454 end Is_Suspicious_Type;
3456 ---------------------------
3457 -- Test_Suspicious_Index --
3458 ---------------------------
3460 procedure Test_Suspicious_Index is
3462 function Length_Reference (N : Node_Id) return Boolean;
3463 -- Check if node N is of the form Name'Length
3466 -- Generate first warning line
3468 ----------------------
3469 -- Length_Reference --
3470 ----------------------
3472 function Length_Reference (N : Node_Id) return Boolean is
3473 R : constant Node_Id := Original_Node (N);
3476 Nkind (R) = N_Attribute_Reference
3477 and then Attribute_Name (R) = Name_Length
3478 and then Is_Entity_Name (Prefix (R))
3479 and then Entity (Prefix (R)) = Ent;
3480 end Length_Reference;
3488 Error_Msg_Uint_1 := Low_Bound;
3489 Error_Msg_FE -- CODEFIX
3490 ("?index for& may assume lower bound of^", X, Ent);
3493 -- Start of processing for Test_Suspicious_Index
3496 -- Nothing to do if subscript does not come from source (we don't
3497 -- want to give garbage warnings on compiler expanded code, e.g. the
3498 -- loops generated for slice assignments. Such junk warnings would
3499 -- be placed on source constructs with no subscript in sight!)
3501 if not Comes_From_Source (Original_Node (X)) then
3505 -- Case where subscript is a constant integer
3507 if Nkind (X) = N_Integer_Literal then
3510 -- Case where original form of subscript is an integer literal
3512 if Nkind (Original_Node (X)) = N_Integer_Literal then
3513 if Intval (X) = Low_Bound then
3514 Error_Msg_FE -- CODEFIX
3515 ("\suggested replacement: `&''First`", X, Ent);
3517 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3518 Error_Msg_FE -- CODEFIX
3519 ("\suggested replacement: `&''First + ^`", X, Ent);
3523 -- Case where original form of subscript is more complex
3526 -- Build string X'First - 1 + expression where the expression
3527 -- is the original subscript. If the expression starts with "1
3528 -- + ", then the "- 1 + 1" is elided.
3530 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3531 Error_Msg_Strlen := 13;
3534 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3535 Tref : constant Source_Buffer_Ptr :=
3536 Source_Text (Get_Source_File_Index (Sref));
3537 -- Tref (Sref) is used to scan the subscript
3540 -- Parentheses counter when scanning subscript
3543 -- Tref (Sref) points to start of subscript
3545 -- Elide - 1 if subscript starts with 1 +
3547 if Tref (Sref .. Sref + 2) = "1 +" then
3548 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3551 elsif Tref (Sref .. Sref + 1) = "1+" then
3552 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3556 -- Now we will copy the subscript to the string buffer
3560 -- Count parens, exit if terminating right paren. Note
3561 -- check to ignore paren appearing as character literal.
3563 if Tref (Sref + 1) = '''
3565 Tref (Sref - 1) = '''
3569 if Tref (Sref) = '(' then
3571 elsif Tref (Sref) = ')' then
3577 -- Done if terminating double dot (slice case)
3580 and then (Tref (Sref .. Sref + 1) = ".."
3582 Tref (Sref .. Sref + 2) = " ..");
3584 -- Quit if we have hit EOF character, something wrong
3586 if Tref (Sref) = EOF then
3590 -- String literals are too much of a pain to handle
3592 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3596 -- If we have a 'Range reference, then this is a case
3597 -- where we cannot easily give a replacement. Don't try!
3599 if Tref (Sref .. Sref + 4) = "range"
3600 and then Tref (Sref - 1) < 'A'
3601 and then Tref (Sref + 5) < 'A'
3606 -- Else store next character
3608 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3609 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3612 -- If we get more than 40 characters then the expression
3613 -- is too long to copy, or something has gone wrong. In
3614 -- either case, just skip the attempt at a suggested fix.
3616 if Error_Msg_Strlen > 40 then
3622 -- Replacement subscript is now in string buffer
3624 Error_Msg_FE -- CODEFIX
3625 ("\suggested replacement: `&~`", Original_Node (X), Ent);
3628 -- Case where subscript is of the form X'Length
3630 elsif Length_Reference (X) then
3632 Error_Msg_Node_2 := Ent;
3634 ("\suggest replacement of `&''Length` by `&''Last`",
3637 -- Case where subscript is of the form X'Length - expression
3639 elsif Nkind (X) = N_Op_Subtract
3640 and then Length_Reference (Left_Opnd (X))
3643 Error_Msg_Node_2 := Ent;
3645 ("\suggest replacement of `&''Length` by `&''Last`",
3646 Left_Opnd (X), Ent);
3648 end Test_Suspicious_Index;
3650 -- Start of processing for Warn_On_Suspicious_Index
3653 -- Only process if warnings activated
3655 if Warn_On_Assumed_Low_Bound then
3657 -- Test if array is simple entity name
3659 if Is_Entity_Name (Name) then
3661 -- Test if array is parameter of unconstrained string type
3663 Ent := Entity (Name);
3667 and then Is_Suspicious_Type (Typ)
3668 and then not Low_Bound_Tested (Ent)
3670 Test_Suspicious_Index;
3674 end Warn_On_Suspicious_Index;
3676 --------------------------------------
3677 -- Warn_On_Unassigned_Out_Parameter --
3678 --------------------------------------
3680 procedure Warn_On_Unassigned_Out_Parameter
3681 (Return_Node : Node_Id;
3682 Scope_Id : Entity_Id)
3688 -- Ignore if procedure or return statement does not come from source
3690 if not Comes_From_Source (Scope_Id)
3691 or else not Comes_From_Source (Return_Node)
3696 -- Loop through formals
3698 Form := First_Formal (Scope_Id);
3699 while Present (Form) loop
3701 -- We are only interested in OUT parameters that come from source
3702 -- and are never set in the source, and furthermore only in scalars
3703 -- since non-scalars generate too many false positives.
3705 if Ekind (Form) = E_Out_Parameter
3706 and then Never_Set_In_Source_Check_Spec (Form)
3707 and then Is_Scalar_Type (Etype (Form))
3708 and then not Present (Unset_Reference (Form))
3710 -- Before we issue the warning, an add ad hoc defence against the
3711 -- most common case of false positives with this warning which is
3712 -- the case where there is a Boolean OUT parameter that has been
3713 -- set, and whose meaning is "ignore the values of the other
3714 -- parameters". We can't of course reliably tell this case at
3715 -- compile time, but the following test kills a lot of false
3716 -- positives, without generating a significant number of false
3717 -- negatives (missed real warnings).
3719 Form2 := First_Formal (Scope_Id);
3720 while Present (Form2) loop
3721 if Ekind (Form2) = E_Out_Parameter
3722 and then Root_Type (Etype (Form2)) = Standard_Boolean
3723 and then not Never_Set_In_Source_Check_Spec (Form2)
3728 Next_Formal (Form2);
3731 -- Here all conditions are met, record possible unset reference
3733 Set_Unset_Reference (Form, Return_Node);
3738 end Warn_On_Unassigned_Out_Parameter;
3740 ---------------------------------
3741 -- Warn_On_Unreferenced_Entity --
3742 ---------------------------------
3744 procedure Warn_On_Unreferenced_Entity
3745 (Spec_E : Entity_Id;
3746 Body_E : Entity_Id := Empty)
3748 E : Entity_Id := Spec_E;
3751 if not Referenced_Check_Spec (E)
3752 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3753 and then not Warnings_Off_Check_Spec (E)
3758 -- Case of variable that is assigned but not read. We suppress
3759 -- the message if the variable is volatile, has an address
3760 -- clause, is aliased, or is a renaming, or is imported.
3762 if Referenced_As_LHS_Check_Spec (E)
3763 and then No (Address_Clause (E))
3764 and then not Is_Volatile (E)
3766 if Warn_On_Modified_Unread
3767 and then not Is_Imported (E)
3768 and then not Is_Aliased (E)
3769 and then No (Renamed_Object (E))
3771 if not Has_Pragma_Unmodified_Check_Spec (E) then
3772 Error_Msg_N -- CODEFIX
3773 ("?variable & is assigned but never read!", E);
3776 Set_Last_Assignment (E, Empty);
3779 -- Normal case of neither assigned nor read (exclude variables
3780 -- referenced as out parameters, since we already generated
3781 -- appropriate warnings at the call point in this case).
3783 elsif not Referenced_As_Out_Parameter (E) then
3785 -- We suppress the message for types for which a valid
3786 -- pragma Unreferenced_Objects has been given, otherwise
3787 -- we go ahead and give the message.
3789 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3791 -- Distinguish renamed case in message
3793 if Present (Renamed_Object (E))
3794 and then Comes_From_Source (Renamed_Object (E))
3796 Error_Msg_N -- CODEFIX
3797 ("?renamed variable & is not referenced!", E);
3799 Error_Msg_N -- CODEFIX
3800 ("?variable & is not referenced!", E);
3806 if Present (Renamed_Object (E))
3807 and then Comes_From_Source (Renamed_Object (E))
3809 Error_Msg_N -- CODEFIX
3810 ("?renamed constant & is not referenced!", E);
3812 Error_Msg_N -- CODEFIX
3813 ("?constant & is not referenced!", E);
3816 when E_In_Parameter |
3817 E_In_Out_Parameter =>
3819 -- Do not emit message for formals of a renaming, because
3820 -- they are never referenced explicitly.
3822 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E))))
3823 /= N_Subprogram_Renaming_Declaration
3825 -- Suppress this message for an IN OUT parameter of a
3826 -- non-scalar type, since it is normal to have only an
3827 -- assignment in such a case.
3829 if Ekind (E) = E_In_Parameter
3830 or else not Referenced_As_LHS_Check_Spec (E)
3831 or else Is_Scalar_Type (Etype (E))
3833 if Present (Body_E) then
3837 if not Is_Trivial_Subprogram (Scope (E)) then
3838 Error_Msg_NE -- CODEFIX
3839 ("?formal parameter & is not referenced!",
3845 when E_Out_Parameter =>
3848 when E_Discriminant =>
3849 Error_Msg_N ("?discriminant & is not referenced!", E);
3851 when E_Named_Integer |
3853 Error_Msg_N -- CODEFIX
3854 ("?named number & is not referenced!", E);
3856 when Formal_Object_Kind =>
3857 Error_Msg_N -- CODEFIX
3858 ("?formal object & is not referenced!", E);
3860 when E_Enumeration_Literal =>
3861 Error_Msg_N -- CODEFIX
3862 ("?literal & is not referenced!", E);
3865 Error_Msg_N -- CODEFIX
3866 ("?function & is not referenced!", E);
3869 Error_Msg_N -- CODEFIX
3870 ("?procedure & is not referenced!", E);
3873 Error_Msg_N -- CODEFIX
3874 ("?package & is not referenced!", E);
3877 Error_Msg_N -- CODEFIX
3878 ("?exception & is not referenced!", E);
3881 Error_Msg_N -- CODEFIX
3882 ("?label & is not referenced!", E);
3884 when E_Generic_Procedure =>
3885 Error_Msg_N -- CODEFIX
3886 ("?generic procedure & is never instantiated!", E);
3888 when E_Generic_Function =>
3889 Error_Msg_N -- CODEFIX
3890 ("?generic function & is never instantiated!", E);
3893 Error_Msg_N -- CODEFIX
3894 ("?type & is not referenced!", E);
3897 Error_Msg_N -- CODEFIX
3898 ("?& is not referenced!", E);
3901 -- Kill warnings on the entity on which the message has been posted
3903 Set_Warnings_Off (E);
3905 end Warn_On_Unreferenced_Entity;
3907 --------------------------------
3908 -- Warn_On_Useless_Assignment --
3909 --------------------------------
3911 procedure Warn_On_Useless_Assignment
3913 N : Node_Id := Empty)
3918 function Check_Ref (N : Node_Id) return Traverse_Result;
3919 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
3920 -- the entity in question is found.
3922 function Test_No_Refs is new Traverse_Func (Check_Ref);
3928 function Check_Ref (N : Node_Id) return Traverse_Result is
3930 -- Check reference to our identifier. We use name equality here
3931 -- because the exception handlers have not yet been analyzed. This
3932 -- is not quite right, but it really does not matter that we fail
3933 -- to output the warning in some obscure cases of name clashes.
3935 if Nkind (N) = N_Identifier
3936 and then Chars (N) = Chars (Ent)
3944 -- Start of processing for Warn_On_Useless_Assignment
3947 -- Check if this is a case we want to warn on, a scalar or access
3948 -- variable with the last assignment field set, with warnings enabled,
3949 -- and which is not imported or exported. We also check that it is OK
3950 -- to capture the value. We are not going to capture any value, but
3951 -- the warning message depends on the same kind of conditions.
3953 if Is_Assignable (Ent)
3954 and then not Is_Return_Object (Ent)
3955 and then Present (Last_Assignment (Ent))
3956 and then not Is_Imported (Ent)
3957 and then not Is_Exported (Ent)
3958 and then Safe_To_Capture_Value (N, Ent)
3959 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
3961 -- Before we issue the message, check covering exception handlers.
3962 -- Search up tree for enclosing statement sequences and handlers.
3964 P := Parent (Last_Assignment (Ent));
3965 while Present (P) loop
3967 -- Something is really wrong if we don't find a handled statement
3968 -- sequence, so just suppress the warning.
3971 Set_Last_Assignment (Ent, Empty);
3974 -- When we hit a package/subprogram body, issue warning and exit
3976 elsif Nkind (P) = N_Subprogram_Body
3977 or else Nkind (P) = N_Package_Body
3979 -- Case of assigned value never referenced
3983 -- Don't give this for OUT and IN OUT formals, since
3984 -- clearly caller may reference the assigned value. Also
3985 -- never give such warnings for internal variables.
3987 if Ekind (Ent) = E_Variable
3988 and then not Is_Internal_Name (Chars (Ent))
3990 if Referenced_As_Out_Parameter (Ent) then
3992 ("?& modified by call, but value never referenced",
3993 Last_Assignment (Ent), Ent);
3995 Error_Msg_NE -- CODEFIX
3996 ("?useless assignment to&, value never referenced!",
3997 Last_Assignment (Ent), Ent);
4001 -- Case of assigned value overwritten
4004 Error_Msg_Sloc := Sloc (N);
4006 if Referenced_As_Out_Parameter (Ent) then
4008 ("?& modified by call, but value overwritten #!",
4009 Last_Assignment (Ent), Ent);
4011 Error_Msg_NE -- CODEFIX
4012 ("?useless assignment to&, value overwritten #!",
4013 Last_Assignment (Ent), Ent);
4017 -- Clear last assignment indication and we are done
4019 Set_Last_Assignment (Ent, Empty);
4022 -- Enclosing handled sequence of statements
4024 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4026 -- Check exception handlers present
4028 if Present (Exception_Handlers (P)) then
4030 -- If we are not at the top level, we regard an inner
4031 -- exception handler as a decisive indicator that we should
4032 -- not generate the warning, since the variable in question
4033 -- may be accessed after an exception in the outer block.
4035 if Nkind (Parent (P)) /= N_Subprogram_Body
4036 and then Nkind (Parent (P)) /= N_Package_Body
4038 Set_Last_Assignment (Ent, Empty);
4041 -- Otherwise we are at the outer level. An exception
4042 -- handler is significant only if it references the
4043 -- variable in question, or if the entity in question
4044 -- is an OUT or IN OUT parameter, which which case
4045 -- the caller can reference it after the exception
4046 -- handler completes.
4049 if Is_Formal (Ent) then
4050 Set_Last_Assignment (Ent, Empty);
4054 X := First (Exception_Handlers (P));
4055 while Present (X) loop
4056 if Test_No_Refs (X) = Abandon then
4057 Set_Last_Assignment (Ent, Empty);
4071 end Warn_On_Useless_Assignment;
4073 ---------------------------------
4074 -- Warn_On_Useless_Assignments --
4075 ---------------------------------
4077 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4080 if Warn_On_Modified_Unread
4081 and then In_Extended_Main_Source_Unit (E)
4083 Ent := First_Entity (E);
4084 while Present (Ent) loop
4085 Warn_On_Useless_Assignment (Ent);
4089 end Warn_On_Useless_Assignments;
4091 -----------------------------
4092 -- Warnings_Off_Check_Spec --
4093 -----------------------------
4095 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4097 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4099 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4100 -- to mess with flags on both entities.
4102 return Has_Warnings_Off (E)
4104 Has_Warnings_Off (Spec_Entity (E));
4107 return Has_Warnings_Off (E);
4109 end Warnings_Off_Check_Spec;