1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2012, 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);
214 end Check_Code_Statement;
216 ---------------------------------
217 -- Check_Infinite_Loop_Warning --
218 ---------------------------------
220 -- The case we look for is a while loop which tests a local variable, where
221 -- there is no obvious direct or possible indirect update of the variable
222 -- within the body of the loop.
224 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
225 Expression : Node_Id := Empty;
226 -- Set to WHILE or EXIT WHEN condition to be tested
228 Ref : Node_Id := Empty;
229 -- Reference in Expression to variable that might not be modified
230 -- in loop, indicating a possible infinite loop.
232 Var : Entity_Id := Empty;
233 -- Corresponding entity (entity of Ref)
235 Function_Call_Found : Boolean := False;
236 -- True if Find_Var found a function call in the condition
238 procedure Find_Var (N : Node_Id);
239 -- Inspect condition to see if it depends on a single entity reference.
240 -- If so, Ref is set to point to the reference node, and Var is set to
241 -- the referenced Entity.
243 function Has_Indirection (T : Entity_Id) return Boolean;
244 -- If the controlling variable is an access type, or is a record type
245 -- with access components, assume that it is changed indirectly and
246 -- suppress the warning. As a concession to low-level programming, in
247 -- particular within Declib, we also suppress warnings on a record
248 -- type that contains components of type Address or Short_Address.
250 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
251 -- Given an entity name, see if the name appears to have something to
252 -- do with I/O or network stuff, and if so, return True. Used to kill
253 -- some false positives on a heuristic basis that such functions will
254 -- likely have some strange side effect dependencies. A rather funny
255 -- kludge, but warning messages are in the heuristics business.
257 function Test_Ref (N : Node_Id) return Traverse_Result;
258 -- Test for reference to variable in question. Returns Abandon if
259 -- matching reference found. Used in instantiation of No_Ref_Found.
261 function No_Ref_Found is new Traverse_Func (Test_Ref);
262 -- Function to traverse body of procedure. Returns Abandon if matching
269 procedure Find_Var (N : Node_Id) is
271 -- Condition is a direct variable reference
273 if Is_Entity_Name (N) then
277 -- Case of condition is a comparison with compile time known value
279 elsif Nkind (N) in N_Op_Compare then
280 if Compile_Time_Known_Value (Right_Opnd (N)) then
281 Find_Var (Left_Opnd (N));
283 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
284 Find_Var (Right_Opnd (N));
286 -- Ignore any other comparison
292 -- If condition is a negation, check its operand
294 elsif Nkind (N) = N_Op_Not then
295 Find_Var (Right_Opnd (N));
297 -- Case of condition is function call
299 elsif Nkind (N) = N_Function_Call then
301 Function_Call_Found := True;
303 -- Forget it if function name is not entity, who knows what
304 -- we might be calling?
306 if not Is_Entity_Name (Name (N)) then
309 -- Forget it if function name is suspicious. A strange test
310 -- but warning generation is in the heuristics business!
312 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
315 -- Forget it if warnings are suppressed on function entity
317 elsif Has_Warnings_Off (Entity (Name (N))) then
321 -- OK, see if we have one argument
324 PA : constant List_Id := Parameter_Associations (N);
327 -- One argument, so check the argument
330 and then List_Length (PA) = 1
332 if Nkind (First (PA)) = N_Parameter_Association then
333 Find_Var (Explicit_Actual_Parameter (First (PA)));
335 Find_Var (First (PA));
345 -- Any other kind of node is not something we warn for
352 ---------------------
353 -- Has_Indirection --
354 ---------------------
356 function Has_Indirection (T : Entity_Id) return Boolean is
361 if Is_Access_Type (T) then
364 elsif Is_Private_Type (T)
365 and then Present (Full_View (T))
366 and then Is_Access_Type (Full_View (T))
370 elsif Is_Record_Type (T) then
373 elsif Is_Private_Type (T)
374 and then Present (Full_View (T))
375 and then Is_Record_Type (Full_View (T))
377 Rec := Full_View (T);
382 Comp := First_Component (Rec);
383 while Present (Comp) loop
384 if Is_Access_Type (Etype (Comp))
385 or else Is_Descendent_Of_Address (Etype (Comp))
390 Next_Component (Comp);
396 ---------------------------------
397 -- Is_Suspicious_Function_Name --
398 ---------------------------------
400 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
403 function Substring_Present (S : String) return Boolean;
404 -- Returns True if name buffer has given string delimited by non-
405 -- alphabetic characters or by end of string. S is lower case.
407 -----------------------
408 -- Substring_Present --
409 -----------------------
411 function Substring_Present (S : String) return Boolean is
412 Len : constant Natural := S'Length;
415 for J in 1 .. Name_Len - (Len - 1) loop
416 if Name_Buffer (J .. J + (Len - 1)) = S
419 or else Name_Buffer (J - 1) not in 'a' .. 'z')
422 or else Name_Buffer (J + Len) not in 'a' .. 'z')
429 end Substring_Present;
431 -- Start of processing for Is_Suspicious_Function_Name
435 while Present (S) and then S /= Standard_Standard loop
436 Get_Name_String (Chars (S));
438 if Substring_Present ("io")
439 or else Substring_Present ("file")
440 or else Substring_Present ("network")
449 end Is_Suspicious_Function_Name;
455 function Test_Ref (N : Node_Id) return Traverse_Result is
457 -- Waste of time to look at the expression we are testing
459 if N = Expression then
462 -- Direct reference to variable in question
464 elsif Is_Entity_Name (N)
465 and then Present (Entity (N))
466 and then Entity (N) = Var
468 -- If this is an lvalue, then definitely abandon, since
469 -- this could be a direct modification of the variable.
471 if May_Be_Lvalue (N) then
475 -- If the condition contains a function call, we consider it may
476 -- be modified by side-effects from a procedure call. Otherwise,
477 -- we consider the condition may not be modified, although that
478 -- might happen if Variable is itself a by-reference parameter,
479 -- and the procedure called modifies the global object referred to
480 -- by Variable, but we actually prefer to issue a warning in this
481 -- odd case. Note that the case where the procedure called has
482 -- visibility over Variable is treated in another case below.
484 if Function_Call_Found then
492 exit when P = Loop_Statement;
494 -- Abandon if at procedure call, or something strange is
495 -- going on (perhaps a node with no parent that should
496 -- have one but does not?) As always, for a warning we
497 -- prefer to just abandon the warning than get into the
498 -- business of complaining about the tree structure here!
501 or else Nkind (P) = N_Procedure_Call_Statement
509 -- Reference to variable renaming variable in question
511 elsif Is_Entity_Name (N)
512 and then Present (Entity (N))
513 and then Ekind (Entity (N)) = E_Variable
514 and then Present (Renamed_Object (Entity (N)))
515 and then Is_Entity_Name (Renamed_Object (Entity (N)))
516 and then Entity (Renamed_Object (Entity (N))) = Var
517 and then May_Be_Lvalue (N)
521 -- Call to subprogram
523 elsif Nkind (N) in N_Subprogram_Call then
525 -- If subprogram is within the scope of the entity we are dealing
526 -- with as the loop variable, then it could modify this parameter,
527 -- so we abandon in this case. In the case of a subprogram that is
528 -- not an entity we also abandon. The check for no entity being
529 -- present is a defense against previous errors.
531 if not Is_Entity_Name (Name (N))
532 or else No (Entity (Name (N)))
533 or else Scope_Within (Entity (Name (N)), Scope (Var))
538 -- If any of the arguments are of type access to subprogram, then
539 -- we may have funny side effects, so no warning in this case.
544 Actual := First_Actual (N);
545 while Present (Actual) loop
546 if Is_Access_Subprogram_Type (Etype (Actual)) then
549 Next_Actual (Actual);
554 -- Declaration of the variable in question
556 elsif Nkind (N) = N_Object_Declaration
557 and then Defining_Identifier (N) = Var
562 -- All OK, continue scan
567 -- Start of processing for Check_Infinite_Loop_Warning
570 -- Skip processing if debug flag gnatd.w is set
572 if Debug_Flag_Dot_W then
576 -- Deal with Iteration scheme present
579 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
582 if Present (Iter) then
586 if Present (Condition (Iter)) then
588 -- Skip processing for while iteration with conditions actions,
589 -- since they make it too complicated to get the warning right.
591 if Present (Condition_Actions (Iter)) then
595 -- Capture WHILE condition
597 Expression := Condition (Iter);
599 -- For iteration, do not process, since loop will always terminate
601 elsif Present (Loop_Parameter_Specification (Iter)) then
607 -- Check chain of EXIT statements, we only process loops that have a
608 -- single exit condition (either a single EXIT WHEN statement, or a
609 -- WHILE loop not containing any EXIT WHEN statements).
612 Ident : constant Node_Id := Identifier (Loop_Statement);
616 -- If we don't have a proper chain set, ignore call entirely. This
617 -- happens because of previous errors.
619 if No (Entity (Ident))
620 or else Ekind (Entity (Ident)) /= E_Loop
622 Check_Error_Detected;
626 -- Otherwise prepare to scan list of EXIT statements
628 Exit_Stmt := First_Exit_Statement (Entity (Ident));
629 while Present (Exit_Stmt) loop
631 -- Check for EXIT WHEN
633 if Present (Condition (Exit_Stmt)) then
635 -- Quit processing if EXIT WHEN in WHILE loop, or more than
636 -- one EXIT WHEN statement present in the loop.
638 if Present (Expression) then
641 -- Otherwise capture condition from EXIT WHEN statement
644 Expression := Condition (Exit_Stmt);
648 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
652 -- Return if no condition to test
654 if No (Expression) then
658 -- Initial conditions met, see if condition is of right form
660 Find_Var (Expression);
662 -- Nothing to do if local variable from source not found. If it's a
663 -- renaming, it is probably renaming something too complicated to deal
667 or else Ekind (Var) /= E_Variable
668 or else Is_Library_Level_Entity (Var)
669 or else not Comes_From_Source (Var)
670 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
674 -- Nothing to do if there is some indirection involved (assume that the
675 -- designated variable might be modified in some way we don't see).
676 -- However, if no function call was found, then we don't care about
677 -- indirections, because the condition must be something like "while X
678 -- /= null loop", so we don't care if X.all is modified in the loop.
680 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
683 -- Same sort of thing for volatile variable, might be modified by
684 -- some other task or by the operating system in some way.
686 elsif Is_Volatile (Var) then
690 -- Filter out case of original statement sequence starting with delay.
691 -- We assume this is a multi-tasking program and that the condition
692 -- is affected by other threads (some kind of busy wait).
695 Fstm : constant Node_Id :=
696 Original_Node (First (Statements (Loop_Statement)));
698 if Nkind (Fstm) = N_Delay_Relative_Statement
699 or else Nkind (Fstm) = N_Delay_Until_Statement
705 -- We have a variable reference of the right form, now we scan the loop
706 -- body to see if it looks like it might not be modified
708 if No_Ref_Found (Loop_Statement) = OK then
710 ("??variable& is not modified in loop body!", Ref, Var);
712 ("\??possible infinite loop!", Ref);
714 end Check_Infinite_Loop_Warning;
716 ----------------------------
717 -- Check_Low_Bound_Tested --
718 ----------------------------
720 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
722 if Comes_From_Source (Expr) then
724 L : constant Node_Id := Left_Opnd (Expr);
725 R : constant Node_Id := Right_Opnd (Expr);
727 if Nkind (L) = N_Attribute_Reference
728 and then Attribute_Name (L) = Name_First
729 and then Is_Entity_Name (Prefix (L))
730 and then Is_Formal (Entity (Prefix (L)))
732 Set_Low_Bound_Tested (Entity (Prefix (L)));
735 if Nkind (R) = N_Attribute_Reference
736 and then Attribute_Name (R) = Name_First
737 and then Is_Entity_Name (Prefix (R))
738 and then Is_Formal (Entity (Prefix (R)))
740 Set_Low_Bound_Tested (Entity (Prefix (R)));
744 end Check_Low_Bound_Tested;
746 ----------------------
747 -- Check_References --
748 ----------------------
750 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
757 Accept_Statement : Node_Id) return Entity_Id;
758 -- For an entry formal entity from an entry declaration, find the
759 -- corresponding body formal from the given accept statement.
761 function Missing_Subunits return Boolean;
762 -- We suppress warnings when there are missing subunits, because this
763 -- may generate too many false positives: entities in a parent may only
764 -- be referenced in one of the subunits. We make an exception for
765 -- subunits that contain no other stubs.
767 procedure Output_Reference_Error (M : String);
768 -- Used to output an error message. Deals with posting the error on the
769 -- body formal in the accept case.
771 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
772 -- This is true if the entity in question is potentially referenceable
773 -- from another unit. This is true for entities in packages that are at
774 -- the library level.
776 function Warnings_Off_E1 return Boolean;
777 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
778 -- or for the base type of E1T.
786 Accept_Statement : Node_Id) return Entity_Id
788 Body_Param : Node_Id;
792 -- Loop to find matching parameter in accept statement
794 Body_Param := First (Parameter_Specifications (Accept_Statement));
795 while Present (Body_Param) loop
796 Body_E := Defining_Identifier (Body_Param);
798 if Chars (Body_E) = Chars (E) then
805 -- Should never fall through, should always find a match
810 ----------------------
811 -- Missing_Subunits --
812 ----------------------
814 function Missing_Subunits return Boolean is
818 if not Unloaded_Subunits then
820 -- Normal compilation, all subunits are present
824 elsif E /= Main_Unit_Entity then
826 -- No warnings on a stub that is not the main unit
830 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
831 D := First (Declarations (Unit_Declaration_Node (E)));
832 while Present (D) loop
834 -- No warnings if the proper body contains nested stubs
836 if Nkind (D) in N_Body_Stub then
846 -- Missing stubs elsewhere
850 end Missing_Subunits;
852 ----------------------------
853 -- Output_Reference_Error --
854 ----------------------------
856 procedure Output_Reference_Error (M : String) is
858 -- Never issue messages for internal names, nor for renamings
860 if Is_Internal_Name (Chars (E1))
861 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
866 -- Don't output message for IN OUT formal unless we have the warning
867 -- flag specifically set. It is a bit odd to distinguish IN OUT
868 -- formals from other cases. This distinction is historical in
869 -- nature. Warnings for IN OUT formals were added fairly late.
871 if Ekind (E1) = E_In_Out_Parameter
872 and then not Check_Unreferenced_Formals
877 -- Other than accept case, post error on defining identifier
882 -- Accept case, find body formal to post the message
885 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
888 end Output_Reference_Error;
890 ----------------------------
891 -- Publicly_Referenceable --
892 ----------------------------
894 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
899 -- A formal parameter is never referenceable outside the body of its
900 -- subprogram or entry.
902 if Is_Formal (Ent) then
906 -- Examine parents to look for a library level package spec. But if
907 -- we find a body or block or other similar construct along the way,
908 -- we cannot be referenced.
915 -- If we get to top of tree, then publicly referenceable
920 -- If we reach a generic package declaration, then always
921 -- consider this referenceable, since any instantiation will
922 -- have access to the entities in the generic package. Note
923 -- that the package itself may not be instantiated, but then
924 -- we will get a warning for the package entity.
926 -- Note that generic formal parameters are themselves not
927 -- publicly referenceable in an instance, and warnings on them
930 when N_Generic_Package_Declaration =>
932 not Is_List_Member (Prev)
933 or else List_Containing (Prev)
934 /= Generic_Formal_Declarations (P);
936 -- Similarly, the generic formals of a generic subprogram are
939 when N_Generic_Subprogram_Declaration =>
940 if Is_List_Member (Prev)
941 and then List_Containing (Prev) =
942 Generic_Formal_Declarations (P)
949 -- If we reach a subprogram body, entity is not referenceable
950 -- unless it is the defining entity of the body. This will
951 -- happen, e.g. when a function is an attribute renaming that
952 -- is rewritten as a body.
954 when N_Subprogram_Body =>
955 if Ent /= Defining_Entity (P) then
961 -- If we reach any other body, definitely not referenceable
963 when N_Package_Body |
971 -- For all other cases, keep looking up tree
978 end Publicly_Referenceable;
980 ---------------------
981 -- Warnings_Off_E1 --
982 ---------------------
984 function Warnings_Off_E1 return Boolean is
986 return Has_Warnings_Off (E1T)
987 or else Has_Warnings_Off (Base_Type (E1T))
988 or else Warnings_Off_Check_Spec (E1);
991 -- Start of processing for Check_References
994 -- No messages if warnings are suppressed, or if we have detected any
995 -- real errors so far (this last check avoids junk messages resulting
996 -- from errors, e.g. a subunit that is not loaded).
998 if Warning_Mode = Suppress
999 or else Serious_Errors_Detected /= 0
1004 -- We also skip the messages if any subunits were not loaded (see
1005 -- comment in Sem_Ch10 to understand how this is set, and why it is
1006 -- necessary to suppress the warnings in this case).
1008 if Missing_Subunits then
1012 -- Otherwise loop through entities, looking for suspicious stuff
1014 E1 := First_Entity (E);
1015 while Present (E1) loop
1018 -- We are only interested in source entities. We also don't issue
1019 -- warnings within instances, since the proper place for such
1020 -- warnings is on the template when it is compiled.
1022 if Comes_From_Source (E1)
1023 and then Instantiation_Location (Sloc (E1)) = No_Location
1025 -- We are interested in variables and out/in-out parameters, but
1026 -- we exclude protected types, too complicated to worry about.
1028 if Ekind (E1) = E_Variable
1030 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1031 and then not Is_Protected_Type (Current_Scope))
1033 -- Case of an unassigned variable
1035 -- First gather any Unset_Reference indication for E1. In the
1036 -- case of a parameter, it is the Spec_Entity that is relevant.
1038 if Ekind (E1) = E_Out_Parameter
1039 and then Present (Spec_Entity (E1))
1041 UR := Unset_Reference (Spec_Entity (E1));
1043 UR := Unset_Reference (E1);
1046 -- Special processing for access types
1049 and then Is_Access_Type (E1T)
1051 -- For access types, the only time we made a UR entry was
1052 -- for a dereference, and so we post the appropriate warning
1053 -- here (note that the dereference may not be explicit in
1054 -- the source, for example in the case of a dispatching call
1055 -- with an anonymous access controlling formal, or of an
1056 -- assignment of a pointer involving discriminant check on
1057 -- the designated object).
1059 if not Warnings_Off_E1 then
1060 Error_Msg_NE ("??& may be null!", UR, E1);
1065 -- Case of variable that could be a constant. Note that we
1066 -- never signal such messages for generic package entities,
1067 -- since a given instance could have modifications outside
1070 elsif Warn_On_Constant
1071 and then (Ekind (E1) = E_Variable
1072 and then Has_Initial_Value (E1))
1073 and then Never_Set_In_Source_Check_Spec (E1)
1074 and then not Address_Taken (E1)
1075 and then not Generic_Package_Spec_Entity (E1)
1077 -- A special case, if this variable is volatile and not
1078 -- imported, it is not helpful to tell the programmer
1079 -- to mark the variable as constant, since this would be
1080 -- illegal by virtue of RM C.6(13).
1082 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1083 and then not Is_Imported (E1)
1086 ("?k?& is not modified, volatile has no effect!", E1);
1088 -- Another special case, Exception_Occurrence, this catches
1089 -- the case of exception choice (and a bit more too, but not
1090 -- worth doing more investigation here).
1092 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1095 -- Here we give the warning if referenced and no pragma
1096 -- Unreferenced or Unmodified is present.
1101 if Ekind (E1) = E_Variable then
1102 if Referenced_Check_Spec (E1)
1103 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1104 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1106 if not Warnings_Off_E1 then
1107 Error_Msg_N -- CODEFIX
1108 ("?k?& is not modified, "
1109 & "could be declared constant!",
1116 -- Other cases of a variable or parameter never set in source
1118 elsif Never_Set_In_Source_Check_Spec (E1)
1120 -- No warning if warning for this case turned off
1122 and then Warn_On_No_Value_Assigned
1124 -- No warning if address taken somewhere
1126 and then not Address_Taken (E1)
1128 -- No warning if explicit initial value
1130 and then not Has_Initial_Value (E1)
1132 -- No warning for generic package spec entities, since we
1133 -- might set them in a child unit or something like that
1135 and then not Generic_Package_Spec_Entity (E1)
1137 -- No warning if fully initialized type, except that for
1138 -- this purpose we do not consider access types to qualify
1139 -- as fully initialized types (relying on an access type
1140 -- variable being null when it is never set is a bit odd!)
1142 -- Also we generate warning for an out parameter that is
1143 -- never referenced, since again it seems odd to rely on
1144 -- default initialization to set an out parameter value.
1146 and then (Is_Access_Type (E1T)
1147 or else Ekind (E1) = E_Out_Parameter
1148 or else not Is_Fully_Initialized_Type (E1T))
1150 -- Do not output complaint about never being assigned a
1151 -- value if a pragma Unmodified applies to the variable
1152 -- we are examining, or if it is a parameter, if there is
1153 -- a pragma Unreferenced for the corresponding spec, or
1154 -- if the type is marked as having unreferenced objects.
1155 -- The last is a little peculiar, but better too few than
1156 -- too many warnings in this situation.
1158 if Has_Pragma_Unreferenced_Objects (E1T)
1159 or else Has_Pragma_Unmodified_Check_Spec (E1)
1163 -- IN OUT parameter case where parameter is referenced. We
1164 -- separate this out, since this is the case where we delay
1165 -- output of the warning until more information is available
1166 -- (about use in an instantiation or address being taken).
1168 elsif Ekind (E1) = E_In_Out_Parameter
1169 and then Referenced_Check_Spec (E1)
1171 -- Suppress warning if private type, and the procedure
1172 -- has a separate declaration in a different unit. This
1173 -- is the case where the client of a package sees only
1174 -- the private type, and it may be quite reasonable
1175 -- for the logical view to be IN OUT, even if the
1176 -- implementation ends up using access types or some
1177 -- other method to achieve the local effect of a
1178 -- modification. On the other hand if the spec and body
1179 -- are in the same unit, we are in the package body and
1180 -- there we have less excuse for a junk IN OUT parameter.
1182 if Has_Private_Declaration (E1T)
1183 and then Present (Spec_Entity (E1))
1184 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1188 -- Suppress warning for any parameter of a dispatching
1189 -- operation, since it is quite reasonable to have an
1190 -- operation that is overridden, and for some subclasses
1191 -- needs the formal to be IN OUT and for others happens
1192 -- not to assign it.
1194 elsif Is_Dispatching_Operation
1195 (Scope (Goto_Spec_Entity (E1)))
1199 -- Suppress warning if composite type contains any access
1200 -- component, since the logical effect of modifying a
1201 -- parameter may be achieved by modifying a referenced
1204 elsif Is_Composite_Type (E1T)
1205 and then Has_Access_Values (E1T)
1209 -- Suppress warning on formals of an entry body. All
1210 -- references are attached to the formal in the entry
1211 -- declaration, which are marked Is_Entry_Formal.
1213 elsif Ekind (Scope (E1)) = E_Entry
1214 and then not Is_Entry_Formal (E1)
1218 -- OK, looks like warning for an IN OUT parameter that
1219 -- could be IN makes sense, but we delay the output of
1220 -- the warning, pending possibly finding out later on
1221 -- that the associated subprogram is used as a generic
1222 -- actual, or its address/access is taken. In these two
1223 -- cases, we suppress the warning because the context may
1224 -- force use of IN OUT, even if in this particular case
1225 -- the formal is not modified.
1228 In_Out_Warnings.Append (E1);
1231 -- Other cases of formals
1233 elsif Is_Formal (E1) then
1234 if not Is_Trivial_Subprogram (Scope (E1)) then
1235 if Referenced_Check_Spec (E1) then
1236 if not Has_Pragma_Unmodified_Check_Spec (E1)
1237 and then not Warnings_Off_E1
1239 Output_Reference_Error
1240 ("?f?formal parameter& is read but "
1241 & "never assigned!");
1244 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1245 and then not Warnings_Off_E1
1247 Output_Reference_Error
1248 ("?f?formal parameter& is not referenced!");
1255 if Referenced (E1) then
1256 if not Has_Unmodified (E1)
1257 and then not Warnings_Off_E1
1259 Output_Reference_Error
1260 ("?v?variable& is read but never assigned!");
1263 elsif not Has_Unreferenced (E1)
1264 and then not Warnings_Off_E1
1266 Output_Reference_Error -- CODEFIX
1267 ("?v?variable& is never read and never assigned!");
1270 -- Deal with special case where this variable is hidden
1271 -- by a loop variable.
1273 if Ekind (E1) = E_Variable
1274 and then Present (Hiding_Loop_Variable (E1))
1275 and then not Warnings_Off_E1
1278 ("?v?for loop implicitly declares loop variable!",
1279 Hiding_Loop_Variable (E1));
1281 Error_Msg_Sloc := Sloc (E1);
1283 ("\?v?declaration hides & declared#!",
1284 Hiding_Loop_Variable (E1));
1291 -- Check for unset reference
1293 if Warn_On_No_Value_Assigned and then Present (UR) then
1295 -- For other than access type, go back to original node to
1296 -- deal with case where original unset reference has been
1297 -- rewritten during expansion.
1299 -- In some cases, the original node may be a type conversion
1300 -- or qualification, and in this case we want the object
1303 UR := Original_Node (UR);
1304 while Nkind (UR) = N_Type_Conversion
1305 or else Nkind (UR) = N_Qualified_Expression
1307 UR := Expression (UR);
1310 -- Here we issue the warning, all checks completed
1312 -- If we have a return statement, this was a case of an OUT
1313 -- parameter not being set at the time of the return. (Note:
1314 -- it can't be N_Extended_Return_Statement, because those
1315 -- are only for functions, and functions do not allow OUT
1318 if not Is_Trivial_Subprogram (Scope (E1)) then
1319 if Nkind (UR) = N_Simple_Return_Statement
1320 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1322 if not Warnings_Off_E1 then
1324 ("?v?OUT parameter& not set before return",
1328 -- If the unset reference is a selected component
1329 -- prefix from source, mention the component as well.
1330 -- If the selected component comes from expansion, all
1331 -- we know is that the entity is not fully initialized
1332 -- at the point of the reference. Locate a random
1333 -- uninitialized component to get a better message.
1335 elsif Nkind (Parent (UR)) = N_Selected_Component then
1336 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1338 if not Comes_From_Source (Parent (UR)) then
1343 Comp := First_Entity (E1T);
1344 while Present (Comp) loop
1345 if Ekind (Comp) = E_Component
1346 and then Nkind (Parent (Comp)) =
1347 N_Component_Declaration
1348 and then No (Expression (Parent (Comp)))
1350 Error_Msg_Node_2 := Comp;
1359 -- Issue proper warning. This is a case of referencing
1360 -- a variable before it has been explicitly assigned.
1361 -- For access types, UR was only set for dereferences,
1362 -- so the issue is that the value may be null.
1364 if not Is_Trivial_Subprogram (Scope (E1)) then
1365 if not Warnings_Off_E1 then
1366 if Is_Access_Type (Etype (Parent (UR))) then
1367 Error_Msg_N ("?`&.&` may be null!", UR);
1370 ("?`&.&` may be referenced before "
1371 & "it has a value!", UR);
1376 -- All other cases of unset reference active
1378 elsif not Warnings_Off_E1 then
1380 ("?& may be referenced before it has a value!",
1389 -- Then check for unreferenced entities. Note that we are only
1390 -- interested in entities whose Referenced flag is not set.
1392 if not Referenced_Check_Spec (E1)
1394 -- If Referenced_As_LHS is set, then that's still interesting
1395 -- (potential "assigned but never read" case), but not if we
1396 -- have pragma Unreferenced, which cancels this warning.
1398 and then (not Referenced_As_LHS_Check_Spec (E1)
1399 or else not Has_Unreferenced (E1))
1401 -- Check that warnings on unreferenced entities are enabled
1404 ((Check_Unreferenced and then not Is_Formal (E1))
1406 -- Case of warning on unreferenced formal
1409 (Check_Unreferenced_Formals and then Is_Formal (E1))
1411 -- Case of warning on unread variables modified by an
1412 -- assignment, or an OUT parameter if it is the only one.
1415 (Warn_On_Modified_Unread
1416 and then Referenced_As_LHS_Check_Spec (E1))
1418 -- Case of warning on any unread OUT parameter (note
1419 -- such indications are only set if the appropriate
1420 -- warning options were set, so no need to recheck here.)
1423 Referenced_As_Out_Parameter_Check_Spec (E1))
1425 -- All other entities, including local packages that cannot be
1426 -- referenced from elsewhere, including those declared within a
1429 and then (Is_Object (E1)
1433 Ekind (E1) = E_Label
1435 Ekind (E1) = E_Exception
1437 Ekind (E1) = E_Named_Integer
1439 Ekind (E1) = E_Named_Real
1441 Is_Overloadable (E1)
1443 -- Package case, if the main unit is a package spec
1444 -- or generic package spec, then there may be a
1445 -- corresponding body that references this package
1446 -- in some other file. Otherwise we can be sure
1447 -- that there is no other reference.
1450 (Ekind (E1) = E_Package
1452 not Is_Package_Or_Generic_Package
1453 (Cunit_Entity (Current_Sem_Unit))))
1455 -- Exclude instantiations, since there is no reason why every
1456 -- entity in an instantiation should be referenced.
1458 and then Instantiation_Location (Sloc (E1)) = No_Location
1460 -- Exclude formal parameters from bodies if the corresponding
1461 -- spec entity has been referenced in the case where there is
1464 and then not (Is_Formal (E1)
1465 and then Ekind (Scope (E1)) = E_Subprogram_Body
1466 and then Present (Spec_Entity (E1))
1467 and then Referenced (Spec_Entity (E1)))
1469 -- Consider private type referenced if full view is referenced.
1470 -- If there is not full view, this is a generic type on which
1471 -- warnings are also useful.
1474 not (Is_Private_Type (E1)
1475 and then Present (Full_View (E1))
1476 and then Referenced (Full_View (E1)))
1478 -- Don't worry about full view, only about private type
1480 and then not Has_Private_Declaration (E1)
1482 -- Eliminate dispatching operations from consideration, we
1483 -- cannot tell if these are referenced or not in any easy
1484 -- manner (note this also catches Adjust/Finalize/Initialize).
1486 and then not Is_Dispatching_Operation (E1)
1488 -- Check entity that can be publicly referenced (we do not give
1489 -- messages for such entities, since there could be other
1490 -- units, not involved in this compilation, that contain
1491 -- relevant references.
1493 and then not Publicly_Referenceable (E1)
1495 -- Class wide types are marked as source entities, but they are
1496 -- not really source entities, and are always created, so we do
1497 -- not care if they are not referenced.
1499 and then Ekind (E1) /= E_Class_Wide_Type
1501 -- Objects other than parameters of task types are allowed to
1502 -- be non-referenced, since they start up tasks!
1504 and then ((Ekind (E1) /= E_Variable
1505 and then Ekind (E1) /= E_Constant
1506 and then Ekind (E1) /= E_Component)
1507 or else not Is_Task_Type (E1T))
1509 -- For subunits, only place warnings on the main unit itself,
1510 -- since parent units are not completely compiled.
1512 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1513 or else Get_Source_Unit (E1) = Main_Unit)
1515 -- No warning on a return object, because these are often
1516 -- created with a single expression and an implicit return.
1517 -- If the object is a variable there will be a warning
1518 -- indicating that it could be declared constant.
1521 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1523 -- Suppress warnings in internal units if not in -gnatg mode
1524 -- (these would be junk warnings for an applications program,
1525 -- since they refer to problems in internal units).
1528 or else not Is_Internal_File_Name
1529 (Unit_File_Name (Get_Source_Unit (E1)))
1531 -- We do not immediately flag the error. This is because we
1532 -- have not expanded generic bodies yet, and they may have
1533 -- the missing reference. So instead we park the entity on a
1534 -- list, for later processing. However for the case of an
1535 -- accept statement we want to output messages now, since
1536 -- we know we already have all information at hand, and we
1537 -- also want to have separate warnings for each accept
1538 -- statement for the same entry.
1540 if Present (Anod) then
1541 pragma Assert (Is_Formal (E1));
1543 -- The unreferenced entity is E1, but post the warning
1544 -- on the body entity for this accept statement.
1546 if not Warnings_Off_E1 then
1547 Warn_On_Unreferenced_Entity
1548 (E1, Body_Formal (E1, Accept_Statement => Anod));
1551 elsif not Warnings_Off_E1 then
1552 Unreferenced_Entities.Append (E1);
1556 -- Generic units are referenced in the generic body, but if they
1557 -- are not public and never instantiated we want to force a
1558 -- warning on them. We treat them as redundant constructs to
1561 elsif Is_Generic_Subprogram (E1)
1562 and then not Is_Instantiated (E1)
1563 and then not Publicly_Referenceable (E1)
1564 and then Instantiation_Depth (Sloc (E1)) = 0
1565 and then Warn_On_Redundant_Constructs
1567 if not Warnings_Off_E1 then
1568 Unreferenced_Entities.Append (E1);
1570 -- Force warning on entity
1572 Set_Referenced (E1, False);
1577 -- Recurse into nested package or block. Do not recurse into a formal
1578 -- package, because the corresponding body is not analyzed.
1581 if (Is_Package_Or_Generic_Package (E1)
1582 and then Nkind (Parent (E1)) = N_Package_Specification
1584 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1585 /= N_Formal_Package_Declaration)
1587 or else Ekind (E1) = E_Block
1589 Check_References (E1);
1594 end Check_References;
1596 ---------------------------
1597 -- Check_Unset_Reference --
1598 ---------------------------
1600 procedure Check_Unset_Reference (N : Node_Id) is
1601 Typ : constant Entity_Id := Etype (N);
1603 function Is_OK_Fully_Initialized return Boolean;
1604 -- This function returns true if the given node N is fully initialized
1605 -- so that the reference is safe as far as this routine is concerned.
1606 -- Safe generally means that the type of N is a fully initialized type.
1607 -- The one special case is that for access types, which are always fully
1608 -- initialized, we don't consider a dereference OK since it will surely
1609 -- be dereferencing a null value, which won't do.
1611 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1612 -- Used to test indexed or selected component or slice to see if the
1613 -- evaluation of the prefix depends on a dereference, and if so, returns
1614 -- True, in which case we always check the prefix, even if we know that
1615 -- the referenced component is initialized. Pref is the prefix to test.
1617 -----------------------------
1618 -- Is_OK_Fully_Initialized --
1619 -----------------------------
1621 function Is_OK_Fully_Initialized return Boolean is
1623 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1626 return Is_Fully_Initialized_Type (Typ);
1628 end Is_OK_Fully_Initialized;
1630 ----------------------------
1631 -- Prefix_Has_Dereference --
1632 ----------------------------
1634 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1636 -- If prefix is of an access type, it certainly needs a dereference
1638 if Is_Access_Type (Etype (Pref)) then
1641 -- If prefix is explicit dereference, that's a dereference for sure
1643 elsif Nkind (Pref) = N_Explicit_Dereference then
1646 -- If prefix is itself a component reference or slice check prefix
1648 elsif Nkind (Pref) = N_Slice
1649 or else Nkind (Pref) = N_Indexed_Component
1650 or else Nkind (Pref) = N_Selected_Component
1652 return Prefix_Has_Dereference (Prefix (Pref));
1654 -- All other cases do not involve a dereference
1659 end Prefix_Has_Dereference;
1661 -- Start of processing for Check_Unset_Reference
1664 -- Nothing to do if warnings suppressed
1666 if Warning_Mode = Suppress then
1670 -- Ignore reference unless it comes from source. Almost always if we
1671 -- have a reference from generated code, it is bogus (e.g. calls to init
1672 -- procs to set default discriminant values).
1674 if not Comes_From_Source (N) then
1678 -- Otherwise see what kind of node we have. If the entity already has an
1679 -- unset reference, it is not necessarily the earliest in the text,
1680 -- because resolution of the prefix of selected components is completed
1681 -- before the resolution of the selected component itself. As a result,
1682 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1683 -- in right-to-left order. If there is already an unset reference, we
1684 -- check whether N is earlier before proceeding.
1688 -- For identifier or expanded name, examine the entity involved
1690 when N_Identifier | N_Expanded_Name =>
1692 E : constant Entity_Id := Entity (N);
1695 if (Ekind (E) = E_Variable
1697 Ekind (E) = E_Out_Parameter)
1698 and then Never_Set_In_Source_Check_Spec (E)
1699 and then not Has_Initial_Value (E)
1700 and then (No (Unset_Reference (E))
1702 Earlier_In_Extended_Unit
1703 (Sloc (N), Sloc (Unset_Reference (E))))
1704 and then not Has_Pragma_Unmodified_Check_Spec (E)
1705 and then not Warnings_Off_Check_Spec (E)
1707 -- We may have an unset reference. The first test is whether
1708 -- this is an access to a discriminant of a record or a
1709 -- component with default initialization. Both of these
1710 -- cases can be ignored, since the actual object that is
1711 -- referenced is definitely initialized. Note that this
1712 -- covers the case of reading discriminants of an OUT
1713 -- parameter, which is OK even in Ada 83.
1715 -- Note that we are only interested in a direct reference to
1716 -- a record component here. If the reference is through an
1717 -- access type, then the access object is being referenced,
1718 -- not the record, and still deserves an unset reference.
1720 if Nkind (Parent (N)) = N_Selected_Component
1721 and not Is_Access_Type (Typ)
1724 ES : constant Entity_Id :=
1725 Entity (Selector_Name (Parent (N)));
1727 if Ekind (ES) = E_Discriminant
1729 (Present (Declaration_Node (ES))
1731 Present (Expression (Declaration_Node (ES))))
1738 -- Exclude fully initialized types
1740 if Is_OK_Fully_Initialized then
1744 -- Here we have a potential unset reference. But before we
1745 -- get worried about it, we have to make sure that the
1746 -- entity declaration is in the same procedure as the
1747 -- reference, since if they are in separate procedures, then
1748 -- we have no idea about sequential execution.
1750 -- The tests in the loop below catch all such cases, but do
1751 -- allow the reference to appear in a loop, block, or
1752 -- package spec that is nested within the declaring scope.
1753 -- As always, it is possible to construct cases where the
1754 -- warning is wrong, that is why it is a warning!
1756 Potential_Unset_Reference : declare
1758 SE : constant Entity_Id := Scope (E);
1760 function Within_Postcondition return Boolean;
1761 -- Returns True iff N is within a Postcondition or
1762 -- Ensures component in a Contract_Case or Test_Case.
1764 --------------------------
1765 -- Within_Postcondition --
1766 --------------------------
1768 function Within_Postcondition return Boolean is
1773 while Present (Nod) loop
1774 if Nkind (Nod) = N_Pragma
1775 and then Pragma_Name (Nod) = Name_Postcondition
1779 elsif Present (Parent (Nod)) then
1782 if Nkind (P) = N_Pragma
1784 (Pragma_Name (P) = Name_Contract_Case
1786 Pragma_Name (P) = Name_Test_Case)
1788 Nod = Get_Ensures_From_CTC_Pragma (P)
1794 Nod := Parent (Nod);
1798 end Within_Postcondition;
1800 -- Start of processing for Potential_Unset_Reference
1803 SR := Current_Scope;
1805 if SR = Standard_Standard
1806 or else Is_Subprogram (SR)
1807 or else Is_Concurrent_Body (SR)
1808 or else Is_Concurrent_Type (SR)
1816 -- Case of reference has an access type. This is a
1817 -- special case since access types are always set to null
1818 -- so cannot be truly uninitialized, but we still want to
1819 -- warn about cases of obvious null dereference.
1821 if Is_Access_Type (Typ) then
1822 Access_Type_Case : declare
1826 (N : Node_Id) return Traverse_Result;
1827 -- Process function for instantiation of Traverse
1828 -- below. Checks if N contains reference to E other
1829 -- than a dereference.
1831 function Ref_In (Nod : Node_Id) return Boolean;
1832 -- Determines whether Nod contains a reference to
1833 -- the entity E that is not a dereference.
1840 (N : Node_Id) return Traverse_Result
1843 if Is_Entity_Name (N)
1844 and then Entity (N) = E
1845 and then not Is_Dereferenced (N)
1857 function Ref_In (Nod : Node_Id) return Boolean is
1858 function Traverse is new Traverse_Func (Process);
1860 return Traverse (Nod) = Abandon;
1863 -- Start of processing for Access_Type_Case
1866 -- Don't bother if we are inside an instance, since
1867 -- the compilation of the generic template is where
1868 -- the warning should be issued.
1874 -- Don't bother if this is not the main unit. If we
1875 -- try to give this warning for with'ed units, we
1876 -- get some false positives, since we do not record
1877 -- references in other units.
1879 if not In_Extended_Main_Source_Unit (E)
1881 not In_Extended_Main_Source_Unit (N)
1886 -- We are only interested in dereferences
1888 if not Is_Dereferenced (N) then
1892 -- One more check, don't bother with references
1893 -- that are inside conditional statements or WHILE
1894 -- loops if the condition references the entity in
1895 -- question. This avoids most false positives.
1902 if (Nkind (P) = N_If_Statement
1904 Nkind (P) = N_Elsif_Part)
1905 and then Ref_In (Condition (P))
1909 elsif Nkind (P) = N_Loop_Statement
1910 and then Present (Iteration_Scheme (P))
1912 Ref_In (Condition (Iteration_Scheme (P)))
1917 end Access_Type_Case;
1920 -- One more check, don't bother if we are within a
1921 -- postcondition, since the expression occurs in a
1922 -- place unrelated to the actual test.
1924 if not Within_Postcondition then
1926 -- Here we definitely have a case for giving a warning
1927 -- for a reference to an unset value. But we don't
1928 -- give the warning now. Instead set Unset_Reference
1929 -- in the identifier involved. The reason for this is
1930 -- that if we find the variable is never ever assigned
1931 -- a value then that warning is more important and
1932 -- there is no point in giving the reference warning.
1934 -- If this is an identifier, set the field directly
1936 if Nkind (N) = N_Identifier then
1937 Set_Unset_Reference (E, N);
1939 -- Otherwise it is an expanded name, so set the field
1940 -- of the actual identifier for the reference.
1943 Set_Unset_Reference (E, Selector_Name (N));
1946 end Potential_Unset_Reference;
1950 -- Indexed component or slice
1952 when N_Indexed_Component | N_Slice =>
1954 -- If prefix does not involve dereferencing an access type, then
1955 -- we know we are OK if the component type is fully initialized,
1956 -- since the component will have been set as part of the default
1959 if not Prefix_Has_Dereference (Prefix (N))
1960 and then Is_OK_Fully_Initialized
1964 -- Look at prefix in access type case, or if the component is not
1965 -- fully initialized.
1968 Check_Unset_Reference (Prefix (N));
1973 when N_Selected_Component =>
1975 Pref : constant Node_Id := Prefix (N);
1976 Ent : constant Entity_Id := Entity (Selector_Name (N));
1979 -- If prefix involves dereferencing an access type, always
1980 -- check the prefix, since the issue then is whether this
1981 -- access value is null.
1983 if Prefix_Has_Dereference (Pref) then
1986 -- Always go to prefix if no selector entity is set. Can this
1987 -- happen in the normal case? Not clear, but it definitely can
1988 -- happen in error cases.
1993 -- For a record component, check some cases where we have
1994 -- reasonable cause to consider that the component is known to
1995 -- be or probably is initialized. In this case, we don't care
1996 -- if the prefix itself was explicitly initialized.
1998 -- Discriminants are always considered initialized
2000 elsif Ekind (Ent) = E_Discriminant then
2003 -- An explicitly initialized component is certainly initialized
2005 elsif Nkind (Parent (Ent)) = N_Component_Declaration
2006 and then Present (Expression (Parent (Ent)))
2010 -- A fully initialized component is initialized
2012 elsif Is_OK_Fully_Initialized then
2016 -- If none of those cases apply, check the record type prefix
2018 Check_Unset_Reference (Pref);
2021 -- For type conversions or qualifications examine the expression
2023 when N_Type_Conversion | N_Qualified_Expression =>
2024 Check_Unset_Reference (Expression (N));
2026 -- For explicit dereference, always check prefix, which will generate
2027 -- an unset reference (since this is a case of dereferencing null).
2029 when N_Explicit_Dereference =>
2030 Check_Unset_Reference (Prefix (N));
2032 -- All other cases are not cases of an unset reference
2038 end Check_Unset_Reference;
2040 ------------------------
2041 -- Check_Unused_Withs --
2042 ------------------------
2044 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2050 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2051 -- This is needed for checking the special renaming case
2053 procedure Check_One_Unit (Unit : Unit_Number_Type);
2054 -- Subsidiary procedure, performs checks for specified unit
2056 --------------------
2057 -- Check_One_Unit --
2058 --------------------
2060 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2061 Is_Visible_Renaming : Boolean := False;
2064 procedure Check_Inner_Package (Pack : Entity_Id);
2065 -- Pack is a package local to a unit in a with_clause. Both the unit
2066 -- and Pack are referenced. If none of the entities in Pack are
2067 -- referenced, then the only occurrence of Pack is in a USE clause
2068 -- or a pragma, and a warning is worthwhile as well.
2070 function Check_System_Aux return Boolean;
2071 -- Before giving a warning on a with_clause for System, check whether
2072 -- a system extension is present.
2074 function Find_Package_Renaming
2076 L : Entity_Id) return Entity_Id;
2077 -- The only reference to a context unit may be in a renaming
2078 -- declaration. If this renaming declares a visible entity, do not
2079 -- warn that the context clause could be moved to the body, because
2080 -- the renaming may be intended to re-export the unit.
2082 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2083 -- This function determines if a package has any visible entities.
2084 -- True is returned if there is at least one declared visible entity,
2085 -- otherwise False is returned (e.g. case of only pragmas present).
2087 -------------------------
2088 -- Check_Inner_Package --
2089 -------------------------
2091 procedure Check_Inner_Package (Pack : Entity_Id) is
2093 Un : constant Node_Id := Sinfo.Unit (Cnode);
2095 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2096 -- If N is a use_clause for Pack, emit warning
2098 procedure Check_Use_Clauses is new
2099 Traverse_Proc (Check_Use_Clause);
2101 ----------------------
2102 -- Check_Use_Clause --
2103 ----------------------
2105 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2109 if Nkind (N) = N_Use_Package_Clause then
2110 Nam := First (Names (N));
2111 while Present (Nam) loop
2112 if Entity (Nam) = Pack then
2113 Error_Msg_Qual_Level := 1;
2114 Error_Msg_NE -- CODEFIX
2115 ("?u?no entities of package& are referenced!",
2117 Error_Msg_Qual_Level := 0;
2125 end Check_Use_Clause;
2127 -- Start of processing for Check_Inner_Package
2130 E := First_Entity (Pack);
2131 while Present (E) loop
2132 if Referenced_Check_Spec (E) then
2139 -- No entities of the package are referenced. Check whether the
2140 -- reference to the package itself is a use clause, and if so
2141 -- place a warning on it.
2143 Check_Use_Clauses (Un);
2144 end Check_Inner_Package;
2146 ----------------------
2147 -- Check_System_Aux --
2148 ----------------------
2150 function Check_System_Aux return Boolean is
2154 if Chars (Lunit) = Name_System
2155 and then Scope (Lunit) = Standard_Standard
2156 and then Present_System_Aux
2158 Ent := First_Entity (System_Aux_Id);
2159 while Present (Ent) loop
2160 if Referenced_Check_Spec (Ent) then
2169 end Check_System_Aux;
2171 ---------------------------
2172 -- Find_Package_Renaming --
2173 ---------------------------
2175 function Find_Package_Renaming
2177 L : Entity_Id) return Entity_Id
2183 Is_Visible_Renaming := False;
2185 E1 := First_Entity (P);
2186 while Present (E1) loop
2187 if Ekind (E1) = E_Package
2188 and then Renamed_Object (E1) = L
2190 Is_Visible_Renaming := not Is_Hidden (E1);
2193 elsif Ekind (E1) = E_Package
2194 and then No (Renamed_Object (E1))
2195 and then not Is_Generic_Instance (E1)
2197 R := Find_Package_Renaming (E1, L);
2200 Is_Visible_Renaming := not Is_Hidden (R);
2209 end Find_Package_Renaming;
2211 --------------------------
2212 -- Has_Visible_Entities --
2213 --------------------------
2215 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2219 -- If unit in context is not a package, it is a subprogram that
2220 -- is not called or a generic unit that is not instantiated
2221 -- in the current unit, and warning is appropriate.
2223 if Ekind (P) /= E_Package then
2227 -- If unit comes from a limited_with clause, look for declaration
2228 -- of shadow entities.
2230 if Present (Limited_View (P)) then
2231 E := First_Entity (Limited_View (P));
2233 E := First_Entity (P);
2237 and then E /= First_Private_Entity (P)
2239 if Comes_From_Source (E)
2240 or else Present (Limited_View (P))
2249 end Has_Visible_Entities;
2251 -- Start of processing for Check_One_Unit
2254 Cnode := Cunit (Unit);
2256 -- Only do check in units that are part of the extended main unit.
2257 -- This is actually a necessary restriction, because in the case of
2258 -- subprogram acting as its own specification, there can be with's in
2259 -- subunits that we will not see.
2261 if not In_Extended_Main_Source_Unit (Cnode) then
2264 -- In configurable run time mode, we remove the bodies of non-inlined
2265 -- subprograms, which may lead to spurious warnings, which are
2266 -- clearly undesirable.
2268 elsif Configurable_Run_Time_Mode
2269 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2274 -- Loop through context items in this unit
2276 Item := First (Context_Items (Cnode));
2277 while Present (Item) loop
2278 if Nkind (Item) = N_With_Clause
2279 and then not Implicit_With (Item)
2280 and then In_Extended_Main_Source_Unit (Item)
2282 Lunit := Entity (Name (Item));
2284 -- Check if this unit is referenced (skip the check if this
2285 -- is explicitly marked by a pragma Unreferenced).
2287 if not Referenced (Lunit)
2288 and then not Has_Unreferenced (Lunit)
2290 -- Suppress warnings in internal units if not in -gnatg mode
2291 -- (these would be junk warnings for an application program,
2292 -- since they refer to problems in internal units).
2295 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2297 -- Here we definitely have a non-referenced unit. If it
2298 -- is the special call for a spec unit, then just set the
2299 -- flag to be read later.
2301 if Unit = Spec_Unit then
2302 Set_Unreferenced_In_Spec (Item);
2304 -- Otherwise simple unreferenced message, but skip this
2305 -- if no visible entities, because that is most likely a
2306 -- case where warning would be false positive (e.g. a
2307 -- package with only a linker options pragma and nothing
2308 -- else or a pragma elaborate with a body library task).
2310 elsif Has_Visible_Entities (Entity (Name (Item))) then
2311 Error_Msg_N -- CODEFIX
2312 ("?u?unit& is not referenced!", Name (Item));
2316 -- If main unit is a renaming of this unit, then we consider
2317 -- the with to be OK (obviously it is needed in this case!)
2318 -- This may be transitive: the unit in the with_clause may
2319 -- itself be a renaming, in which case both it and the main
2320 -- unit rename the same ultimate package.
2322 elsif Present (Renamed_Entity (Munite))
2324 (Renamed_Entity (Munite) = Lunit
2325 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2329 -- If this unit is referenced, and it is a package, we do
2330 -- another test, to see if any of the entities in the package
2331 -- are referenced. If none of the entities are referenced, we
2332 -- still post a warning. This occurs if the only use of the
2333 -- package is in a use clause, or in a package renaming
2334 -- declaration. This check is skipped for packages that are
2335 -- renamed in a spec, since the entities in such a package are
2336 -- visible to clients via the renaming.
2338 elsif Ekind (Lunit) = E_Package
2339 and then not Renamed_In_Spec (Lunit)
2341 -- If Is_Instantiated is set, it means that the package is
2342 -- implicitly instantiated (this is the case of parent
2343 -- instance or an actual for a generic package formal), and
2344 -- this counts as a reference.
2346 if Is_Instantiated (Lunit) then
2349 -- If no entities in package, and there is a pragma
2350 -- Elaborate_Body present, then assume that this with is
2351 -- done for purposes of this elaboration.
2353 elsif No (First_Entity (Lunit))
2354 and then Has_Pragma_Elaborate_Body (Lunit)
2358 -- Otherwise see if any entities have been referenced
2361 if Limited_Present (Item) then
2362 Ent := First_Entity (Limited_View (Lunit));
2364 Ent := First_Entity (Lunit);
2368 -- No more entities, and we did not find one that was
2369 -- referenced. Means we have a definite case of a with
2370 -- none of whose entities was referenced.
2374 -- If in spec, just set the flag
2376 if Unit = Spec_Unit then
2377 Set_No_Entities_Ref_In_Spec (Item);
2379 elsif Check_System_Aux then
2382 -- Else give the warning
2386 Has_Unreferenced (Entity (Name (Item)))
2388 Error_Msg_N -- CODEFIX
2389 ("?u?no entities of & are referenced!",
2393 -- Look for renamings of this package, and flag
2394 -- them as well. If the original package has
2395 -- warnings off, we suppress the warning on the
2396 -- renaming as well.
2398 Pack := Find_Package_Renaming (Munite, Lunit);
2401 and then not Has_Warnings_Off (Lunit)
2402 and then not Has_Unreferenced (Pack)
2404 Error_Msg_NE -- CODEFIX
2405 ("?u?no entities of & are referenced!",
2406 Unit_Declaration_Node (Pack),
2413 -- Case of entity being referenced. The reference may
2414 -- come from a limited_with_clause, in which case the
2415 -- limited view of the entity carries the flag.
2417 elsif Referenced_Check_Spec (Ent)
2418 or else Referenced_As_LHS_Check_Spec (Ent)
2419 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2421 (From_With_Type (Ent)
2422 and then Is_Incomplete_Type (Ent)
2423 and then Present (Non_Limited_View (Ent))
2424 and then Referenced (Non_Limited_View (Ent)))
2426 -- This means that the with is indeed fine, in that
2427 -- it is definitely needed somewhere, and we can
2428 -- quit worrying about this one...
2430 -- Except for one little detail: if either of the
2431 -- flags was set during spec processing, this is
2432 -- where we complain that the with could be moved
2433 -- from the spec. If the spec contains a visible
2434 -- renaming of the package, inhibit warning to move
2435 -- with_clause to body.
2437 if Ekind (Munite) = E_Package_Body then
2439 Find_Package_Renaming
2440 (Spec_Entity (Munite), Lunit);
2445 -- If a renaming is present in the spec do not warn
2446 -- because the body or child unit may depend on it.
2449 and then Renamed_Entity (Pack) = Lunit
2453 elsif Unreferenced_In_Spec (Item) then
2454 Error_Msg_N -- CODEFIX
2455 ("?u?unit& is not referenced in spec!",
2458 elsif No_Entities_Ref_In_Spec (Item) then
2459 Error_Msg_N -- CODEFIX
2460 ("?u?no entities of & are referenced in spec!",
2464 if Ekind (Ent) = E_Package then
2465 Check_Inner_Package (Ent);
2471 if not Is_Visible_Renaming then
2472 Error_Msg_N -- CODEFIX
2473 ("\?u?with clause might be moved to body!",
2479 -- Move to next entity to continue search
2487 -- For a generic package, the only interesting kind of
2488 -- reference is an instantiation, since entities cannot be
2489 -- referenced directly.
2491 elsif Is_Generic_Unit (Lunit) then
2493 -- Unit was never instantiated, set flag for case of spec
2494 -- call, or give warning for normal call.
2496 if not Is_Instantiated (Lunit) then
2497 if Unit = Spec_Unit then
2498 Set_Unreferenced_In_Spec (Item);
2500 Error_Msg_N -- CODEFIX
2501 ("?u?unit& is never instantiated!", Name (Item));
2504 -- If unit was indeed instantiated, make sure that flag is
2505 -- not set showing it was uninstantiated in the spec, and if
2506 -- so, give warning.
2508 elsif Unreferenced_In_Spec (Item) then
2510 ("?u?unit& is not instantiated in spec!", Name (Item));
2511 Error_Msg_N -- CODEFIX
2512 ("\?u?with clause can be moved to body!", Name (Item));
2521 -- Start of processing for Check_Unused_Withs
2524 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then
2528 -- Flag any unused with clauses, but skip this step if we are compiling
2529 -- a subunit on its own, since we do not have enough information to
2530 -- determine whether with's are used. We will get the relevant warnings
2531 -- when we compile the parent. This is the normal style of GNAT
2532 -- compilation in any case.
2534 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2538 -- Process specified units
2540 if Spec_Unit = No_Unit then
2542 -- For main call, check all units
2544 for Unit in Main_Unit .. Last_Unit loop
2545 Check_One_Unit (Unit);
2549 -- For call for spec, check only the spec
2551 Check_One_Unit (Spec_Unit);
2553 end Check_Unused_Withs;
2555 ---------------------------------
2556 -- Generic_Package_Spec_Entity --
2557 ---------------------------------
2559 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2563 if Is_Package_Body_Entity (E) then
2569 if S = Standard_Standard then
2572 elsif Ekind (S) = E_Generic_Package then
2575 elsif Ekind (S) = E_Package then
2583 end Generic_Package_Spec_Entity;
2585 ----------------------
2586 -- Goto_Spec_Entity --
2587 ----------------------
2589 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2592 and then Present (Spec_Entity (E))
2594 return Spec_Entity (E);
2598 end Goto_Spec_Entity;
2600 --------------------------------------
2601 -- Has_Pragma_Unmodified_Check_Spec --
2602 --------------------------------------
2604 function Has_Pragma_Unmodified_Check_Spec
2605 (E : Entity_Id) return Boolean
2608 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2610 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2611 -- to mess with Unmodified flags on both body and spec entities.
2613 return Has_Unmodified (E)
2615 Has_Unmodified (Spec_Entity (E));
2618 return Has_Unmodified (E);
2620 end Has_Pragma_Unmodified_Check_Spec;
2622 ----------------------------------------
2623 -- Has_Pragma_Unreferenced_Check_Spec --
2624 ----------------------------------------
2626 function Has_Pragma_Unreferenced_Check_Spec
2627 (E : Entity_Id) return Boolean
2630 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2632 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2633 -- to mess with flags on both entities.
2635 return Has_Unreferenced (E)
2637 Has_Unreferenced (Spec_Entity (E));
2640 return Has_Unreferenced (E);
2642 end Has_Pragma_Unreferenced_Check_Spec;
2648 procedure Initialize is
2650 Warnings_Off_Pragmas.Init;
2651 Unreferenced_Entities.Init;
2652 In_Out_Warnings.Init;
2655 ------------------------------------
2656 -- Never_Set_In_Source_Check_Spec --
2657 ------------------------------------
2659 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2661 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2662 return Never_Set_In_Source (E)
2664 Never_Set_In_Source (Spec_Entity (E));
2666 return Never_Set_In_Source (E);
2668 end Never_Set_In_Source_Check_Spec;
2670 -------------------------------------
2671 -- Operand_Has_Warnings_Suppressed --
2672 -------------------------------------
2674 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2676 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2677 -- Function used to check one node to see if it is or was originally
2678 -- a reference to an entity for which Warnings are off. If so, Abandon
2679 -- is returned, otherwise OK_Orig is returned to continue the traversal
2680 -- of the original expression.
2682 function Traverse is new Traverse_Func (Check_For_Warnings);
2683 -- Function used to traverse tree looking for warnings
2685 ------------------------
2686 -- Check_For_Warnings --
2687 ------------------------
2689 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2690 R : constant Node_Id := Original_Node (N);
2693 if Nkind (R) in N_Has_Entity
2694 and then Present (Entity (R))
2695 and then Has_Warnings_Off (Entity (R))
2701 end Check_For_Warnings;
2703 -- Start of processing for Operand_Has_Warnings_Suppressed
2706 return Traverse (N) = Abandon;
2708 -- If any exception occurs, then something has gone wrong, and this is
2709 -- only a minor aesthetic issue anyway, so just say we did not find what
2710 -- we are looking for, rather than blow up.
2715 end Operand_Has_Warnings_Suppressed;
2717 -----------------------------------------
2718 -- Output_Non_Modified_In_Out_Warnings --
2719 -----------------------------------------
2721 procedure Output_Non_Modified_In_Out_Warnings is
2723 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2724 -- Given a formal parameter entity E, determines if there is a reason to
2725 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2726 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2727 -- if we have seen the address of the subprogram being taken, or if the
2728 -- subprogram is used as a generic actual (in the latter cases the
2729 -- context may force use of IN OUT, even if the parameter is not
2730 -- modifies for this particular case.
2732 -----------------------
2733 -- No_Warn_On_In_Out --
2734 -----------------------
2736 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2737 S : constant Entity_Id := Scope (E);
2738 SE : constant Entity_Id := Spec_Entity (E);
2741 -- Do not warn if address is taken, since funny business may be going
2742 -- on in treating the parameter indirectly as IN OUT.
2744 if Address_Taken (S)
2745 or else (Present (SE) and then Address_Taken (Scope (SE)))
2749 -- Do not warn if used as a generic actual, since the generic may be
2750 -- what is forcing the use of an "unnecessary" IN OUT.
2752 elsif Used_As_Generic_Actual (S)
2753 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2757 -- Else test warnings off
2759 elsif Warnings_Off_Check_Spec (S) then
2762 -- All tests for suppressing warning failed
2767 end No_Warn_On_In_Out;
2769 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2772 -- Loop through entities for which a warning may be needed
2774 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2776 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2779 -- Suppress warning in specific cases (see details in comments for
2780 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2782 if Has_Pragma_Unmodified_Check_Spec (E1)
2783 or else No_Warn_On_In_Out (E1)
2787 -- Here we generate the warning
2790 -- If -gnatwc is set then output message that we could be IN
2792 if not Is_Trivial_Subprogram (Scope (E1)) then
2793 if Warn_On_Constant then
2795 ("?u?formal parameter & is not modified!", E1);
2797 ("\?u?mode could be IN instead of `IN OUT`!", E1);
2799 -- We do not generate warnings for IN OUT parameters
2800 -- unless we have at least -gnatwu. This is deliberately
2801 -- inconsistent with the treatment of variables, but
2802 -- otherwise we get too many unexpected warnings in
2805 elsif Check_Unreferenced then
2807 ("?u?formal parameter& is read but "
2808 & "never assigned!", E1);
2812 -- Kill any other warnings on this entity, since this is the
2813 -- one that should dominate any other unreferenced warning.
2815 Set_Warnings_Off (E1);
2819 end Output_Non_Modified_In_Out_Warnings;
2821 ----------------------------------------
2822 -- Output_Obsolescent_Entity_Warnings --
2823 ----------------------------------------
2825 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2826 P : constant Node_Id := Parent (N);
2832 -- Do not output message if we are the scope of standard. This means
2833 -- we have a reference from a context clause from when it is originally
2834 -- processed, and that's too early to tell whether it is an obsolescent
2835 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2836 -- sure that we have a later call when the scope is available. This test
2837 -- also eliminates all messages for use clauses, which is fine (we do
2838 -- not want messages for use clauses, since they are always redundant
2839 -- with respect to the associated with clause).
2841 if S = Standard_Standard then
2845 -- Do not output message if we are in scope of an obsolescent package
2849 if Is_Obsolescent (S) then
2854 exit when S = Standard_Standard;
2857 -- Here we will output the message
2859 Error_Msg_Sloc := Sloc (E);
2861 -- Case of with clause
2863 if Nkind (P) = N_With_Clause then
2864 if Ekind (E) = E_Package then
2866 ("??with of obsolescent package& declared#", N, E);
2867 elsif Ekind (E) = E_Procedure then
2869 ("??with of obsolescent procedure& declared#", N, E);
2872 ("??with of obsolescent function& declared#", N, E);
2875 -- If we do not have a with clause, then ignore any reference to an
2876 -- obsolescent package name. We only want to give the one warning of
2877 -- withing the package, not one each time it is used to qualify.
2879 elsif Ekind (E) = E_Package then
2882 -- Procedure call statement
2884 elsif Nkind (P) = N_Procedure_Call_Statement then
2886 ("??call to obsolescent procedure& declared#", N, E);
2890 elsif Nkind (P) = N_Function_Call then
2892 ("??call to obsolescent function& declared#", N, E);
2894 -- Reference to obsolescent type
2896 elsif Is_Type (E) then
2898 ("??reference to obsolescent type& declared#", N, E);
2900 -- Reference to obsolescent component
2902 elsif Ekind_In (E, E_Component, E_Discriminant) then
2904 ("??reference to obsolescent component& declared#", N, E);
2906 -- Reference to obsolescent variable
2908 elsif Ekind (E) = E_Variable then
2910 ("??reference to obsolescent variable& declared#", N, E);
2912 -- Reference to obsolescent constant
2914 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then
2916 ("??reference to obsolescent constant& declared#", N, E);
2918 -- Reference to obsolescent enumeration literal
2920 elsif Ekind (E) = E_Enumeration_Literal then
2922 ("??reference to obsolescent enumeration literal& declared#", N, E);
2924 -- Generic message for any other case we missed
2928 ("??reference to obsolescent entity& declared#", N, E);
2931 -- Output additional warning if present
2933 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2934 if Obsolescent_Warnings.Table (J).Ent = E then
2935 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2936 Error_Msg_Strlen := Name_Len;
2937 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2938 Error_Msg_N ("\\??~", N);
2942 end Output_Obsolescent_Entity_Warnings;
2944 ----------------------------------
2945 -- Output_Unreferenced_Messages --
2946 ----------------------------------
2948 procedure Output_Unreferenced_Messages is
2950 for J in Unreferenced_Entities.First ..
2951 Unreferenced_Entities.Last
2953 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2955 end Output_Unreferenced_Messages;
2957 -----------------------------------------
2958 -- Output_Unused_Warnings_Off_Warnings --
2959 -----------------------------------------
2961 procedure Output_Unused_Warnings_Off_Warnings is
2963 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2965 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2966 N : Node_Id renames Wentry.N;
2967 E : Node_Id renames Wentry.E;
2970 -- Turn off Warnings_Off, or we won't get the warning!
2972 Set_Warnings_Off (E, False);
2974 -- Nothing to do if pragma was used to suppress a general warning
2976 if Warnings_Off_Used (E) then
2979 -- If pragma was used both in unmodified and unreferenced contexts
2980 -- then that's as good as the general case, no warning.
2982 elsif Warnings_Off_Used_Unmodified (E)
2984 Warnings_Off_Used_Unreferenced (E)
2988 -- Used only in context where Unmodified would have worked
2990 elsif Warnings_Off_Used_Unmodified (E) then
2992 ("?W?could use Unmodified instead of "
2993 & "Warnings Off for &", Pragma_Identifier (N), E);
2995 -- Used only in context where Unreferenced would have worked
2997 elsif Warnings_Off_Used_Unreferenced (E) then
2999 ("?W?could use Unreferenced instead of "
3000 & "Warnings Off for &", Pragma_Identifier (N), E);
3006 ("?W?pragma Warnings Off for & unused, "
3007 & "could be omitted", N, E);
3011 end Output_Unused_Warnings_Off_Warnings;
3013 ---------------------------
3014 -- Referenced_Check_Spec --
3015 ---------------------------
3017 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3019 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3020 return Referenced (E) or else Referenced (Spec_Entity (E));
3022 return Referenced (E);
3024 end Referenced_Check_Spec;
3026 ----------------------------------
3027 -- Referenced_As_LHS_Check_Spec --
3028 ----------------------------------
3030 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3032 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3033 return Referenced_As_LHS (E)
3034 or else Referenced_As_LHS (Spec_Entity (E));
3036 return Referenced_As_LHS (E);
3038 end Referenced_As_LHS_Check_Spec;
3040 --------------------------------------------
3041 -- Referenced_As_Out_Parameter_Check_Spec --
3042 --------------------------------------------
3044 function Referenced_As_Out_Parameter_Check_Spec
3045 (E : Entity_Id) return Boolean
3048 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3049 return Referenced_As_Out_Parameter (E)
3050 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3052 return Referenced_As_Out_Parameter (E);
3054 end Referenced_As_Out_Parameter_Check_Spec;
3056 -----------------------------
3057 -- Warn_On_Known_Condition --
3058 -----------------------------
3060 procedure Warn_On_Known_Condition (C : Node_Id) is
3062 Orig : constant Node_Id := Original_Node (C);
3063 Test_Result : Boolean;
3065 function Is_Known_Branch return Boolean;
3066 -- If the type of the condition is Boolean, the constant value of the
3067 -- condition is a boolean literal. If the type is a derived boolean
3068 -- type, the constant is wrapped in a type conversion of the derived
3069 -- literal. If the value of the condition is not a literal, no warnings
3070 -- can be produced. This function returns True if the result can be
3071 -- determined, and Test_Result is set True/False accordingly. Otherwise
3072 -- False is returned, and Test_Result is unchanged.
3074 procedure Track (N : Node_Id; Loc : Node_Id);
3075 -- Adds continuation warning(s) pointing to reason (assignment or test)
3076 -- for the operand of the conditional having a known value (or at least
3077 -- enough is known about the value to issue the warning). N is the node
3078 -- which is judged to have a known value. Loc is the warning location.
3080 ---------------------
3081 -- Is_Known_Branch --
3082 ---------------------
3084 function Is_Known_Branch return Boolean is
3086 if Etype (C) = Standard_Boolean
3087 and then Is_Entity_Name (C)
3089 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3091 Test_Result := Entity (C) = Standard_True;
3094 elsif Is_Boolean_Type (Etype (C))
3095 and then Nkind (C) = N_Unchecked_Type_Conversion
3096 and then Is_Entity_Name (Expression (C))
3097 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3100 Chars (Entity (Expression (C))) = Chars (Standard_True);
3106 end Is_Known_Branch;
3112 procedure Track (N : Node_Id; Loc : Node_Id) is
3113 Nod : constant Node_Id := Original_Node (N);
3116 if Nkind (Nod) in N_Op_Compare then
3117 Track (Left_Opnd (Nod), Loc);
3118 Track (Right_Opnd (Nod), Loc);
3120 elsif Is_Entity_Name (Nod)
3121 and then Is_Object (Entity (Nod))
3124 CV : constant Node_Id := Current_Value (Entity (Nod));
3127 if Present (CV) then
3128 Error_Msg_Sloc := Sloc (CV);
3130 if Nkind (CV) not in N_Subexpr then
3131 Error_Msg_N ("\\?(see test #)", Loc);
3133 elsif Nkind (Parent (CV)) =
3134 N_Case_Statement_Alternative
3136 Error_Msg_N ("\\?(see case alternative #)", Loc);
3139 Error_Msg_N ("\\?(see assignment #)", Loc);
3146 -- Start of processing for Warn_On_Known_Condition
3149 -- Adjust SCO condition if from source
3152 and then Comes_From_Source (Orig)
3153 and then Is_Known_Branch
3159 Atrue := Test_Result;
3161 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3165 Set_SCO_Condition (Orig, Atrue);
3169 -- Argument replacement in an inlined body can make conditions static.
3170 -- Do not emit warnings in this case.
3172 if In_Inlined_Body then
3176 if Constant_Condition_Warnings
3177 and then Is_Known_Branch
3178 and then Comes_From_Source (Orig)
3179 and then not In_Instance
3181 -- Don't warn if comparison of result of attribute against a constant
3182 -- value, since this is likely legitimate conditional compilation.
3184 if Nkind (Orig) in N_Op_Compare
3185 and then Compile_Time_Known_Value (Right_Opnd (Orig))
3186 and then Nkind (Original_Node (Left_Opnd (Orig))) =
3187 N_Attribute_Reference
3192 -- See if this is in a statement or a declaration
3196 -- If tree is not attached, do not issue warning (this is very
3197 -- peculiar, and probably arises from some other error condition)
3202 -- If we are in a declaration, then no warning, since in practice
3203 -- conditionals in declarations are used for intended tests which
3204 -- may be known at compile time, e.g. things like
3206 -- x : constant Integer := 2 + (Word'Size = 32);
3208 -- And a warning is annoying in such cases
3210 elsif Nkind (P) in N_Declaration
3212 Nkind (P) in N_Later_Decl_Item
3216 -- Don't warn in assert or check pragma, since presumably tests in
3217 -- such a context are very definitely intended, and might well be
3218 -- known at compile time. Note that we have to test the original
3219 -- node, since assert pragmas get rewritten at analysis time.
3221 elsif Nkind (Original_Node (P)) = N_Pragma
3222 and then (Pragma_Name (Original_Node (P)) = Name_Assert
3224 Pragma_Name (Original_Node (P)) = Name_Check)
3229 exit when Is_Statement (P);
3233 -- Here we issue the warning unless some sub-operand has warnings
3234 -- set off, in which case we suppress the warning for the node. If
3235 -- the original expression is an inequality, it has been expanded
3236 -- into a negation, and the value of the original expression is the
3237 -- negation of the equality. If the expression is an entity that
3238 -- appears within a negation, it is clearer to flag the negation
3239 -- itself, and report on its constant value.
3241 if not Operand_Has_Warnings_Suppressed (C) then
3243 True_Branch : Boolean := Test_Result;
3244 Cond : Node_Id := C;
3247 if Present (Parent (C))
3248 and then Nkind (Parent (C)) = N_Op_Not
3250 True_Branch := not True_Branch;
3255 if Is_Entity_Name (Original_Node (C))
3256 and then Nkind (Cond) /= N_Op_Not
3259 ("object & is always True?c?", Cond, Original_Node (C));
3260 Track (Original_Node (C), Cond);
3263 Error_Msg_N ("condition is always True?c?", Cond);
3268 Error_Msg_N ("condition is always False?c?", Cond);
3274 end Warn_On_Known_Condition;
3276 ---------------------------------------
3277 -- Warn_On_Modified_As_Out_Parameter --
3278 ---------------------------------------
3280 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3283 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3284 or else Warn_On_All_Unread_Out_Parameters;
3285 end Warn_On_Modified_As_Out_Parameter;
3287 ---------------------------------
3288 -- Warn_On_Overlapping_Actuals --
3289 ---------------------------------
3291 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3292 Act1, Act2 : Node_Id;
3293 Form1, Form2 : Entity_Id;
3296 if not Warn_On_Overlap then
3300 -- Exclude calls rewritten as enumeration literals
3302 if Nkind (N) not in N_Subprogram_Call then
3306 -- Exclude calls to library subprograms. Container operations specify
3307 -- safe behavior when source and target coincide.
3309 if Is_Predefined_File_Name
3310 (Unit_File_Name (Get_Source_Unit (Sloc (Subp))))
3315 Form1 := First_Formal (Subp);
3316 Act1 := First_Actual (N);
3317 while Present (Form1) and then Present (Act1) loop
3318 if Ekind (Form1) /= E_In_Parameter then
3319 Form2 := First_Formal (Subp);
3320 Act2 := First_Actual (N);
3321 while Present (Form2) and then Present (Act2) loop
3323 and then Ekind (Form2) /= E_Out_Parameter
3325 (Denotes_Same_Object (Act1, Act2)
3327 Denotes_Same_Prefix (Act1, Act2))
3329 -- Exclude generic types and guard against previous errors
3332 or else No (Etype (Act1))
3333 or else No (Etype (Act2))
3337 elsif Is_Generic_Type (Etype (Act1))
3339 Is_Generic_Type (Etype (Act2))
3343 -- If the actual is a function call in prefix notation,
3344 -- there is no real overlap.
3346 elsif Nkind (Act2) = N_Function_Call then
3349 -- If type is not by-copy we can assume that the aliasing is
3353 Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3363 -- Find matching actual
3365 Act := First_Actual (N);
3366 Form := First_Formal (Subp);
3367 while Act /= Act2 loop
3372 if Is_Elementary_Type (Etype (Act1))
3373 and then Ekind (Form2) = E_In_Parameter
3375 null; -- No real aliasing
3377 elsif Is_Elementary_Type (Etype (Act2))
3378 and then Ekind (Form2) = E_In_Parameter
3382 -- If the call was written in prefix notation, and
3383 -- thus its prefix before rewriting was a selected
3384 -- component, count only visible actuals in the call.
3386 elsif Is_Entity_Name (First_Actual (N))
3387 and then Nkind (Original_Node (N)) = Nkind (N)
3388 and then Nkind (Name (Original_Node (N))) =
3389 N_Selected_Component
3391 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3393 Entity (Prefix (Name (Original_Node (N)))) =
3394 Entity (First_Actual (N))
3396 if Act1 = First_Actual (N) then
3398 ("`IN OUT` prefix overlaps with "
3399 & "actual for&?I?", Act1, Form);
3402 -- For greater clarity, give name of formal.
3404 Error_Msg_Node_2 := Form;
3406 ("writable actual for & overlaps with "
3407 & "actual for&?I?", Act1, Form);
3411 Error_Msg_Node_2 := Form;
3413 ("writable actual for & overlaps with"
3414 & " actual for&?I?", Act1, Form1);
3422 Next_Formal (Form2);
3427 Next_Formal (Form1);
3430 end Warn_On_Overlapping_Actuals;
3432 ------------------------------
3433 -- Warn_On_Suspicious_Index --
3434 ------------------------------
3436 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3439 -- Set to lower bound for a suspicious type
3442 -- Entity for array reference
3447 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3448 -- Tests to see if Typ is a type for which we may have a suspicious
3449 -- index, namely an unconstrained array type, whose lower bound is
3450 -- either zero or one. If so, True is returned, and Low_Bound is set
3451 -- to this lower bound. If not, False is returned, and Low_Bound is
3452 -- undefined on return.
3454 -- For now, we limit this to standard string types, so any other
3455 -- unconstrained types return False. We may change our minds on this
3456 -- later on, but strings seem the most important case.
3458 procedure Test_Suspicious_Index;
3459 -- Test if index is of suspicious type and if so, generate warning
3461 ------------------------
3462 -- Is_Suspicious_Type --
3463 ------------------------
3465 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3469 if Is_Array_Type (Typ)
3470 and then not Is_Constrained (Typ)
3471 and then Number_Dimensions (Typ) = 1
3472 and then (Root_Type (Typ) = Standard_String
3474 Root_Type (Typ) = Standard_Wide_String
3476 Root_Type (Typ) = Standard_Wide_Wide_String)
3477 and then not Has_Warnings_Off (Typ)
3479 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3481 if Compile_Time_Known_Value (LB) then
3482 Low_Bound := Expr_Value (LB);
3483 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3488 end Is_Suspicious_Type;
3490 ---------------------------
3491 -- Test_Suspicious_Index --
3492 ---------------------------
3494 procedure Test_Suspicious_Index is
3496 function Length_Reference (N : Node_Id) return Boolean;
3497 -- Check if node N is of the form Name'Length
3500 -- Generate first warning line
3502 ----------------------
3503 -- Length_Reference --
3504 ----------------------
3506 function Length_Reference (N : Node_Id) return Boolean is
3507 R : constant Node_Id := Original_Node (N);
3510 Nkind (R) = N_Attribute_Reference
3511 and then Attribute_Name (R) = Name_Length
3512 and then Is_Entity_Name (Prefix (R))
3513 and then Entity (Prefix (R)) = Ent;
3514 end Length_Reference;
3522 Error_Msg_Uint_1 := Low_Bound;
3523 Error_Msg_FE -- CODEFIX
3524 ("?w?index for& may assume lower bound of^", X, Ent);
3527 -- Start of processing for Test_Suspicious_Index
3530 -- Nothing to do if subscript does not come from source (we don't
3531 -- want to give garbage warnings on compiler expanded code, e.g. the
3532 -- loops generated for slice assignments. Such junk warnings would
3533 -- be placed on source constructs with no subscript in sight!)
3535 if not Comes_From_Source (Original_Node (X)) then
3539 -- Case where subscript is a constant integer
3541 if Nkind (X) = N_Integer_Literal then
3544 -- Case where original form of subscript is an integer literal
3546 if Nkind (Original_Node (X)) = N_Integer_Literal then
3547 if Intval (X) = Low_Bound then
3548 Error_Msg_FE -- CODEFIX
3549 ("\?w?suggested replacement: `&''First`", X, Ent);
3551 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3552 Error_Msg_FE -- CODEFIX
3553 ("\?w?suggested replacement: `&''First + ^`", X, Ent);
3557 -- Case where original form of subscript is more complex
3560 -- Build string X'First - 1 + expression where the expression
3561 -- is the original subscript. If the expression starts with "1
3562 -- + ", then the "- 1 + 1" is elided.
3564 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3565 Error_Msg_Strlen := 13;
3568 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3569 Tref : constant Source_Buffer_Ptr :=
3570 Source_Text (Get_Source_File_Index (Sref));
3571 -- Tref (Sref) is used to scan the subscript
3574 -- Parentheses counter when scanning subscript
3577 -- Tref (Sref) points to start of subscript
3579 -- Elide - 1 if subscript starts with 1 +
3581 if Tref (Sref .. Sref + 2) = "1 +" then
3582 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3585 elsif Tref (Sref .. Sref + 1) = "1+" then
3586 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3590 -- Now we will copy the subscript to the string buffer
3594 -- Count parens, exit if terminating right paren. Note
3595 -- check to ignore paren appearing as character literal.
3597 if Tref (Sref + 1) = '''
3599 Tref (Sref - 1) = '''
3603 if Tref (Sref) = '(' then
3605 elsif Tref (Sref) = ')' then
3611 -- Done if terminating double dot (slice case)
3614 and then (Tref (Sref .. Sref + 1) = ".."
3616 Tref (Sref .. Sref + 2) = " ..");
3618 -- Quit if we have hit EOF character, something wrong
3620 if Tref (Sref) = EOF then
3624 -- String literals are too much of a pain to handle
3626 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3630 -- If we have a 'Range reference, then this is a case
3631 -- where we cannot easily give a replacement. Don't try!
3633 if Tref (Sref .. Sref + 4) = "range"
3634 and then Tref (Sref - 1) < 'A'
3635 and then Tref (Sref + 5) < 'A'
3640 -- Else store next character
3642 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3643 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3646 -- If we get more than 40 characters then the expression
3647 -- is too long to copy, or something has gone wrong. In
3648 -- either case, just skip the attempt at a suggested fix.
3650 if Error_Msg_Strlen > 40 then
3656 -- Replacement subscript is now in string buffer
3658 Error_Msg_FE -- CODEFIX
3659 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent);
3662 -- Case where subscript is of the form X'Length
3664 elsif Length_Reference (X) then
3666 Error_Msg_Node_2 := Ent;
3668 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3671 -- Case where subscript is of the form X'Length - expression
3673 elsif Nkind (X) = N_Op_Subtract
3674 and then Length_Reference (Left_Opnd (X))
3677 Error_Msg_Node_2 := Ent;
3679 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3680 Left_Opnd (X), Ent);
3682 end Test_Suspicious_Index;
3684 -- Start of processing for Warn_On_Suspicious_Index
3687 -- Only process if warnings activated
3689 if Warn_On_Assumed_Low_Bound then
3691 -- Test if array is simple entity name
3693 if Is_Entity_Name (Name) then
3695 -- Test if array is parameter of unconstrained string type
3697 Ent := Entity (Name);
3701 and then Is_Suspicious_Type (Typ)
3702 and then not Low_Bound_Tested (Ent)
3704 Test_Suspicious_Index;
3708 end Warn_On_Suspicious_Index;
3710 --------------------------------------
3711 -- Warn_On_Unassigned_Out_Parameter --
3712 --------------------------------------
3714 procedure Warn_On_Unassigned_Out_Parameter
3715 (Return_Node : Node_Id;
3716 Scope_Id : Entity_Id)
3722 -- Ignore if procedure or return statement does not come from source
3724 if not Comes_From_Source (Scope_Id)
3725 or else not Comes_From_Source (Return_Node)
3730 -- Loop through formals
3732 Form := First_Formal (Scope_Id);
3733 while Present (Form) loop
3735 -- We are only interested in OUT parameters that come from source
3736 -- and are never set in the source, and furthermore only in scalars
3737 -- since non-scalars generate too many false positives.
3739 if Ekind (Form) = E_Out_Parameter
3740 and then Never_Set_In_Source_Check_Spec (Form)
3741 and then Is_Scalar_Type (Etype (Form))
3742 and then not Present (Unset_Reference (Form))
3744 -- Before we issue the warning, an add ad hoc defence against the
3745 -- most common case of false positives with this warning which is
3746 -- the case where there is a Boolean OUT parameter that has been
3747 -- set, and whose meaning is "ignore the values of the other
3748 -- parameters". We can't of course reliably tell this case at
3749 -- compile time, but the following test kills a lot of false
3750 -- positives, without generating a significant number of false
3751 -- negatives (missed real warnings).
3753 Form2 := First_Formal (Scope_Id);
3754 while Present (Form2) loop
3755 if Ekind (Form2) = E_Out_Parameter
3756 and then Root_Type (Etype (Form2)) = Standard_Boolean
3757 and then not Never_Set_In_Source_Check_Spec (Form2)
3762 Next_Formal (Form2);
3765 -- Here all conditions are met, record possible unset reference
3767 Set_Unset_Reference (Form, Return_Node);
3772 end Warn_On_Unassigned_Out_Parameter;
3774 ---------------------------------
3775 -- Warn_On_Unreferenced_Entity --
3776 ---------------------------------
3778 procedure Warn_On_Unreferenced_Entity
3779 (Spec_E : Entity_Id;
3780 Body_E : Entity_Id := Empty)
3782 E : Entity_Id := Spec_E;
3785 if not Referenced_Check_Spec (E)
3786 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3787 and then not Warnings_Off_Check_Spec (E)
3792 -- Case of variable that is assigned but not read. We suppress
3793 -- the message if the variable is volatile, has an address
3794 -- clause, is aliased, or is a renaming, or is imported.
3796 if Referenced_As_LHS_Check_Spec (E)
3797 and then No (Address_Clause (E))
3798 and then not Is_Volatile (E)
3800 if Warn_On_Modified_Unread
3801 and then not Is_Imported (E)
3802 and then not Is_Aliased (E)
3803 and then No (Renamed_Object (E))
3805 if not Has_Pragma_Unmodified_Check_Spec (E) then
3806 Error_Msg_N -- CODEFIX
3807 ("?u?variable & is assigned but never read!", E);
3810 Set_Last_Assignment (E, Empty);
3813 -- Normal case of neither assigned nor read (exclude variables
3814 -- referenced as out parameters, since we already generated
3815 -- appropriate warnings at the call point in this case).
3817 elsif not Referenced_As_Out_Parameter (E) then
3819 -- We suppress the message for types for which a valid
3820 -- pragma Unreferenced_Objects has been given, otherwise
3821 -- we go ahead and give the message.
3823 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3825 -- Distinguish renamed case in message
3827 if Present (Renamed_Object (E))
3828 and then Comes_From_Source (Renamed_Object (E))
3830 Error_Msg_N -- CODEFIX
3831 ("?u?renamed variable & is not referenced!", E);
3833 Error_Msg_N -- CODEFIX
3834 ("?u?variable & is not referenced!", E);
3840 if Present (Renamed_Object (E))
3841 and then Comes_From_Source (Renamed_Object (E))
3843 Error_Msg_N -- CODEFIX
3844 ("?u?renamed constant & is not referenced!", E);
3846 Error_Msg_N -- CODEFIX
3847 ("?u?constant & is not referenced!", E);
3850 when E_In_Parameter |
3851 E_In_Out_Parameter =>
3853 -- Do not emit message for formals of a renaming, because
3854 -- they are never referenced explicitly.
3856 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /=
3857 N_Subprogram_Renaming_Declaration
3859 -- Suppress this message for an IN OUT parameter of a
3860 -- non-scalar type, since it is normal to have only an
3861 -- assignment in such a case.
3863 if Ekind (E) = E_In_Parameter
3864 or else not Referenced_As_LHS_Check_Spec (E)
3865 or else Is_Scalar_Type (Etype (E))
3867 if Present (Body_E) then
3871 if not Is_Trivial_Subprogram (Scope (E)) then
3872 Error_Msg_NE -- CODEFIX
3873 ("?u?formal parameter & is not referenced!",
3879 when E_Out_Parameter =>
3882 when E_Discriminant =>
3883 Error_Msg_N ("?u?discriminant & is not referenced!", E);
3885 when E_Named_Integer |
3887 Error_Msg_N -- CODEFIX
3888 ("?u?named number & is not referenced!", E);
3890 when Formal_Object_Kind =>
3891 Error_Msg_N -- CODEFIX
3892 ("?u?formal object & is not referenced!", E);
3894 when E_Enumeration_Literal =>
3895 Error_Msg_N -- CODEFIX
3896 ("?u?literal & is not referenced!", E);
3899 Error_Msg_N -- CODEFIX
3900 ("?u?function & is not referenced!", E);
3903 Error_Msg_N -- CODEFIX
3904 ("?u?procedure & is not referenced!", E);
3907 Error_Msg_N -- CODEFIX
3908 ("?u?package & is not referenced!", E);
3911 Error_Msg_N -- CODEFIX
3912 ("?u?exception & is not referenced!", E);
3915 Error_Msg_N -- CODEFIX
3916 ("?u?label & is not referenced!", E);
3918 when E_Generic_Procedure =>
3919 Error_Msg_N -- CODEFIX
3920 ("?u?generic procedure & is never instantiated!", E);
3922 when E_Generic_Function =>
3923 Error_Msg_N -- CODEFIX
3924 ("?u?generic function & is never instantiated!", E);
3927 Error_Msg_N -- CODEFIX
3928 ("?u?type & is not referenced!", E);
3931 Error_Msg_N -- CODEFIX
3932 ("?u?& is not referenced!", E);
3935 -- Kill warnings on the entity on which the message has been posted
3937 Set_Warnings_Off (E);
3939 end Warn_On_Unreferenced_Entity;
3941 --------------------------------
3942 -- Warn_On_Useless_Assignment --
3943 --------------------------------
3945 procedure Warn_On_Useless_Assignment
3947 N : Node_Id := Empty)
3952 function Check_Ref (N : Node_Id) return Traverse_Result;
3953 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
3954 -- the entity in question is found.
3956 function Test_No_Refs is new Traverse_Func (Check_Ref);
3962 function Check_Ref (N : Node_Id) return Traverse_Result is
3964 -- Check reference to our identifier. We use name equality here
3965 -- because the exception handlers have not yet been analyzed. This
3966 -- is not quite right, but it really does not matter that we fail
3967 -- to output the warning in some obscure cases of name clashes.
3969 if Nkind (N) = N_Identifier
3970 and then Chars (N) = Chars (Ent)
3978 -- Start of processing for Warn_On_Useless_Assignment
3981 -- Check if this is a case we want to warn on, a scalar or access
3982 -- variable with the last assignment field set, with warnings enabled,
3983 -- and which is not imported or exported. We also check that it is OK
3984 -- to capture the value. We are not going to capture any value, but
3985 -- the warning message depends on the same kind of conditions.
3987 if Is_Assignable (Ent)
3988 and then not Is_Return_Object (Ent)
3989 and then Present (Last_Assignment (Ent))
3990 and then not Is_Imported (Ent)
3991 and then not Is_Exported (Ent)
3992 and then Safe_To_Capture_Value (N, Ent)
3993 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
3995 -- Before we issue the message, check covering exception handlers.
3996 -- Search up tree for enclosing statement sequences and handlers.
3998 P := Parent (Last_Assignment (Ent));
3999 while Present (P) loop
4001 -- Something is really wrong if we don't find a handled statement
4002 -- sequence, so just suppress the warning.
4005 Set_Last_Assignment (Ent, Empty);
4008 -- When we hit a package/subprogram body, issue warning and exit
4010 elsif Nkind (P) = N_Subprogram_Body
4011 or else Nkind (P) = N_Package_Body
4013 -- Case of assigned value never referenced
4017 LA : constant Node_Id := Last_Assignment (Ent);
4020 -- Don't give this for OUT and IN OUT formals, since
4021 -- clearly caller may reference the assigned value. Also
4022 -- never give such warnings for internal variables.
4024 if Ekind (Ent) = E_Variable
4025 and then not Is_Internal_Name (Chars (Ent))
4027 -- Give appropriate message, distinguishing between
4028 -- assignment statements and out parameters.
4030 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4031 N_Parameter_Association)
4034 ("?m?& modified by call, but value never "
4035 & "referenced", LA, Ent);
4038 Error_Msg_NE -- CODEFIX
4039 ("?m?useless assignment to&, value never "
4040 & "referenced!", LA, Ent);
4045 -- Case of assigned value overwritten
4049 LA : constant Node_Id := Last_Assignment (Ent);
4052 Error_Msg_Sloc := Sloc (N);
4054 -- Give appropriate message, distinguishing between
4055 -- assignment statements and out parameters.
4057 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4058 N_Parameter_Association)
4061 ("?m?& modified by call, but value overwritten #!",
4064 Error_Msg_NE -- CODEFIX
4065 ("?m?useless assignment to&, value overwritten #!",
4071 -- Clear last assignment indication and we are done
4073 Set_Last_Assignment (Ent, Empty);
4076 -- Enclosing handled sequence of statements
4078 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4080 -- Check exception handlers present
4082 if Present (Exception_Handlers (P)) then
4084 -- If we are not at the top level, we regard an inner
4085 -- exception handler as a decisive indicator that we should
4086 -- not generate the warning, since the variable in question
4087 -- may be accessed after an exception in the outer block.
4089 if Nkind (Parent (P)) /= N_Subprogram_Body
4090 and then Nkind (Parent (P)) /= N_Package_Body
4092 Set_Last_Assignment (Ent, Empty);
4095 -- Otherwise we are at the outer level. An exception
4096 -- handler is significant only if it references the
4097 -- variable in question, or if the entity in question
4098 -- is an OUT or IN OUT parameter, which which case
4099 -- the caller can reference it after the exception
4100 -- handler completes.
4103 if Is_Formal (Ent) then
4104 Set_Last_Assignment (Ent, Empty);
4108 X := First (Exception_Handlers (P));
4109 while Present (X) loop
4110 if Test_No_Refs (X) = Abandon then
4111 Set_Last_Assignment (Ent, Empty);
4125 end Warn_On_Useless_Assignment;
4127 ---------------------------------
4128 -- Warn_On_Useless_Assignments --
4129 ---------------------------------
4131 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4134 if Warn_On_Modified_Unread
4135 and then In_Extended_Main_Source_Unit (E)
4137 Ent := First_Entity (E);
4138 while Present (Ent) loop
4139 Warn_On_Useless_Assignment (Ent);
4143 end Warn_On_Useless_Assignments;
4145 -----------------------------
4146 -- Warnings_Off_Check_Spec --
4147 -----------------------------
4149 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4151 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4153 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4154 -- to mess with flags on both entities.
4156 return Has_Warnings_Off (E)
4158 Has_Warnings_Off (Spec_Entity (E));
4161 return Has_Warnings_Off (E);
4163 end Warnings_Off_Check_Spec;