1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2013, 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);
647 -- If an unconditional exit statement is the last statement in the
648 -- loop, assume that no warning is needed, without any attempt at
649 -- checking whether the exit is reachable.
651 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then
655 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
659 -- Return if no condition to test
661 if No (Expression) then
665 -- Initial conditions met, see if condition is of right form
667 Find_Var (Expression);
669 -- Nothing to do if local variable from source not found. If it's a
670 -- renaming, it is probably renaming something too complicated to deal
674 or else Ekind (Var) /= E_Variable
675 or else Is_Library_Level_Entity (Var)
676 or else not Comes_From_Source (Var)
677 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
681 -- Nothing to do if there is some indirection involved (assume that the
682 -- designated variable might be modified in some way we don't see).
683 -- However, if no function call was found, then we don't care about
684 -- indirections, because the condition must be something like "while X
685 -- /= null loop", so we don't care if X.all is modified in the loop.
687 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
690 -- Same sort of thing for volatile variable, might be modified by
691 -- some other task or by the operating system in some way.
693 elsif Is_Volatile (Var) then
697 -- Filter out case of original statement sequence starting with delay.
698 -- We assume this is a multi-tasking program and that the condition
699 -- is affected by other threads (some kind of busy wait).
702 Fstm : constant Node_Id :=
703 Original_Node (First (Statements (Loop_Statement)));
705 if Nkind (Fstm) = N_Delay_Relative_Statement
706 or else Nkind (Fstm) = N_Delay_Until_Statement
712 -- We have a variable reference of the right form, now we scan the loop
713 -- body to see if it looks like it might not be modified
715 if No_Ref_Found (Loop_Statement) = OK then
717 ("??variable& is not modified in loop body!", Ref, Var);
719 ("\??possible infinite loop!", Ref);
721 end Check_Infinite_Loop_Warning;
723 ----------------------------
724 -- Check_Low_Bound_Tested --
725 ----------------------------
727 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
729 if Comes_From_Source (Expr) then
731 L : constant Node_Id := Left_Opnd (Expr);
732 R : constant Node_Id := Right_Opnd (Expr);
734 if Nkind (L) = N_Attribute_Reference
735 and then Attribute_Name (L) = Name_First
736 and then Is_Entity_Name (Prefix (L))
737 and then Is_Formal (Entity (Prefix (L)))
739 Set_Low_Bound_Tested (Entity (Prefix (L)));
742 if Nkind (R) = N_Attribute_Reference
743 and then Attribute_Name (R) = Name_First
744 and then Is_Entity_Name (Prefix (R))
745 and then Is_Formal (Entity (Prefix (R)))
747 Set_Low_Bound_Tested (Entity (Prefix (R)));
751 end Check_Low_Bound_Tested;
753 ----------------------
754 -- Check_References --
755 ----------------------
757 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
764 Accept_Statement : Node_Id) return Entity_Id;
765 -- For an entry formal entity from an entry declaration, find the
766 -- corresponding body formal from the given accept statement.
768 function Missing_Subunits return Boolean;
769 -- We suppress warnings when there are missing subunits, because this
770 -- may generate too many false positives: entities in a parent may only
771 -- be referenced in one of the subunits. We make an exception for
772 -- subunits that contain no other stubs.
774 procedure Output_Reference_Error (M : String);
775 -- Used to output an error message. Deals with posting the error on the
776 -- body formal in the accept case.
778 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
779 -- This is true if the entity in question is potentially referenceable
780 -- from another unit. This is true for entities in packages that are at
781 -- the library level.
783 function Warnings_Off_E1 return Boolean;
784 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
785 -- or for the base type of E1T.
793 Accept_Statement : Node_Id) return Entity_Id
795 Body_Param : Node_Id;
799 -- Loop to find matching parameter in accept statement
801 Body_Param := First (Parameter_Specifications (Accept_Statement));
802 while Present (Body_Param) loop
803 Body_E := Defining_Identifier (Body_Param);
805 if Chars (Body_E) = Chars (E) then
812 -- Should never fall through, should always find a match
817 ----------------------
818 -- Missing_Subunits --
819 ----------------------
821 function Missing_Subunits return Boolean is
825 if not Unloaded_Subunits then
827 -- Normal compilation, all subunits are present
831 elsif E /= Main_Unit_Entity then
833 -- No warnings on a stub that is not the main unit
837 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
838 D := First (Declarations (Unit_Declaration_Node (E)));
839 while Present (D) loop
841 -- No warnings if the proper body contains nested stubs
843 if Nkind (D) in N_Body_Stub then
853 -- Missing stubs elsewhere
857 end Missing_Subunits;
859 ----------------------------
860 -- Output_Reference_Error --
861 ----------------------------
863 procedure Output_Reference_Error (M : String) is
865 -- Never issue messages for internal names, nor for renamings
867 if Is_Internal_Name (Chars (E1))
868 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
873 -- Don't output message for IN OUT formal unless we have the warning
874 -- flag specifically set. It is a bit odd to distinguish IN OUT
875 -- formals from other cases. This distinction is historical in
876 -- nature. Warnings for IN OUT formals were added fairly late.
878 if Ekind (E1) = E_In_Out_Parameter
879 and then not Check_Unreferenced_Formals
884 -- Other than accept case, post error on defining identifier
889 -- Accept case, find body formal to post the message
892 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
895 end Output_Reference_Error;
897 ----------------------------
898 -- Publicly_Referenceable --
899 ----------------------------
901 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
906 -- A formal parameter is never referenceable outside the body of its
907 -- subprogram or entry.
909 if Is_Formal (Ent) then
913 -- Examine parents to look for a library level package spec. But if
914 -- we find a body or block or other similar construct along the way,
915 -- we cannot be referenced.
922 -- If we get to top of tree, then publicly referenceable
927 -- If we reach a generic package declaration, then always
928 -- consider this referenceable, since any instantiation will
929 -- have access to the entities in the generic package. Note
930 -- that the package itself may not be instantiated, but then
931 -- we will get a warning for the package entity.
933 -- Note that generic formal parameters are themselves not
934 -- publicly referenceable in an instance, and warnings on them
937 when N_Generic_Package_Declaration =>
939 not Is_List_Member (Prev)
940 or else List_Containing (Prev)
941 /= Generic_Formal_Declarations (P);
943 -- Similarly, the generic formals of a generic subprogram are
946 when N_Generic_Subprogram_Declaration =>
947 if Is_List_Member (Prev)
948 and then List_Containing (Prev) =
949 Generic_Formal_Declarations (P)
956 -- If we reach a subprogram body, entity is not referenceable
957 -- unless it is the defining entity of the body. This will
958 -- happen, e.g. when a function is an attribute renaming that
959 -- is rewritten as a body.
961 when N_Subprogram_Body =>
962 if Ent /= Defining_Entity (P) then
968 -- If we reach any other body, definitely not referenceable
970 when N_Package_Body |
978 -- For all other cases, keep looking up tree
985 end Publicly_Referenceable;
987 ---------------------
988 -- Warnings_Off_E1 --
989 ---------------------
991 function Warnings_Off_E1 return Boolean is
993 return Has_Warnings_Off (E1T)
994 or else Has_Warnings_Off (Base_Type (E1T))
995 or else Warnings_Off_Check_Spec (E1);
998 -- Start of processing for Check_References
1001 -- No messages if warnings are suppressed, or if we have detected any
1002 -- real errors so far (this last check avoids junk messages resulting
1003 -- from errors, e.g. a subunit that is not loaded).
1005 if Warning_Mode = Suppress
1006 or else Serious_Errors_Detected /= 0
1011 -- We also skip the messages if any subunits were not loaded (see
1012 -- comment in Sem_Ch10 to understand how this is set, and why it is
1013 -- necessary to suppress the warnings in this case).
1015 if Missing_Subunits then
1019 -- Otherwise loop through entities, looking for suspicious stuff
1021 E1 := First_Entity (E);
1022 while Present (E1) loop
1025 -- We are only interested in source entities. We also don't issue
1026 -- warnings within instances, since the proper place for such
1027 -- warnings is on the template when it is compiled.
1029 if Comes_From_Source (E1)
1030 and then Instantiation_Location (Sloc (E1)) = No_Location
1032 -- We are interested in variables and out/in-out parameters, but
1033 -- we exclude protected types, too complicated to worry about.
1035 if Ekind (E1) = E_Variable
1037 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1038 and then not Is_Protected_Type (Current_Scope))
1040 -- Case of an unassigned variable
1042 -- First gather any Unset_Reference indication for E1. In the
1043 -- case of a parameter, it is the Spec_Entity that is relevant.
1045 if Ekind (E1) = E_Out_Parameter
1046 and then Present (Spec_Entity (E1))
1048 UR := Unset_Reference (Spec_Entity (E1));
1050 UR := Unset_Reference (E1);
1053 -- Special processing for access types
1056 and then Is_Access_Type (E1T)
1058 -- For access types, the only time we made a UR entry was
1059 -- for a dereference, and so we post the appropriate warning
1060 -- here (note that the dereference may not be explicit in
1061 -- the source, for example in the case of a dispatching call
1062 -- with an anonymous access controlling formal, or of an
1063 -- assignment of a pointer involving discriminant check on
1064 -- the designated object).
1066 if not Warnings_Off_E1 then
1067 Error_Msg_NE ("??& may be null!", UR, E1);
1072 -- Case of variable that could be a constant. Note that we
1073 -- never signal such messages for generic package entities,
1074 -- since a given instance could have modifications outside
1077 elsif Warn_On_Constant
1078 and then (Ekind (E1) = E_Variable
1079 and then Has_Initial_Value (E1))
1080 and then Never_Set_In_Source_Check_Spec (E1)
1081 and then not Address_Taken (E1)
1082 and then not Generic_Package_Spec_Entity (E1)
1084 -- A special case, if this variable is volatile and not
1085 -- imported, it is not helpful to tell the programmer
1086 -- to mark the variable as constant, since this would be
1087 -- illegal by virtue of RM C.6(13).
1089 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1090 and then not Is_Imported (E1)
1093 ("?k?& is not modified, volatile has no effect!", E1);
1095 -- Another special case, Exception_Occurrence, this catches
1096 -- the case of exception choice (and a bit more too, but not
1097 -- worth doing more investigation here).
1099 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1102 -- Here we give the warning if referenced and no pragma
1103 -- Unreferenced or Unmodified is present.
1108 if Ekind (E1) = E_Variable then
1109 if Referenced_Check_Spec (E1)
1110 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1111 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1113 if not Warnings_Off_E1 then
1114 Error_Msg_N -- CODEFIX
1115 ("?k?& is not modified, "
1116 & "could be declared constant!",
1123 -- Other cases of a variable or parameter never set in source
1125 elsif Never_Set_In_Source_Check_Spec (E1)
1127 -- No warning if warning for this case turned off
1129 and then Warn_On_No_Value_Assigned
1131 -- No warning if address taken somewhere
1133 and then not Address_Taken (E1)
1135 -- No warning if explicit initial value
1137 and then not Has_Initial_Value (E1)
1139 -- No warning for generic package spec entities, since we
1140 -- might set them in a child unit or something like that
1142 and then not Generic_Package_Spec_Entity (E1)
1144 -- No warning if fully initialized type, except that for
1145 -- this purpose we do not consider access types to qualify
1146 -- as fully initialized types (relying on an access type
1147 -- variable being null when it is never set is a bit odd!)
1149 -- Also we generate warning for an out parameter that is
1150 -- never referenced, since again it seems odd to rely on
1151 -- default initialization to set an out parameter value.
1153 and then (Is_Access_Type (E1T)
1154 or else Ekind (E1) = E_Out_Parameter
1155 or else not Is_Fully_Initialized_Type (E1T))
1157 -- Do not output complaint about never being assigned a
1158 -- value if a pragma Unmodified applies to the variable
1159 -- we are examining, or if it is a parameter, if there is
1160 -- a pragma Unreferenced for the corresponding spec, or
1161 -- if the type is marked as having unreferenced objects.
1162 -- The last is a little peculiar, but better too few than
1163 -- too many warnings in this situation.
1165 if Has_Pragma_Unreferenced_Objects (E1T)
1166 or else Has_Pragma_Unmodified_Check_Spec (E1)
1170 -- IN OUT parameter case where parameter is referenced. We
1171 -- separate this out, since this is the case where we delay
1172 -- output of the warning until more information is available
1173 -- (about use in an instantiation or address being taken).
1175 elsif Ekind (E1) = E_In_Out_Parameter
1176 and then Referenced_Check_Spec (E1)
1178 -- Suppress warning if private type, and the procedure
1179 -- has a separate declaration in a different unit. This
1180 -- is the case where the client of a package sees only
1181 -- the private type, and it may be quite reasonable
1182 -- for the logical view to be IN OUT, even if the
1183 -- implementation ends up using access types or some
1184 -- other method to achieve the local effect of a
1185 -- modification. On the other hand if the spec and body
1186 -- are in the same unit, we are in the package body and
1187 -- there we have less excuse for a junk IN OUT parameter.
1189 if Has_Private_Declaration (E1T)
1190 and then Present (Spec_Entity (E1))
1191 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1195 -- Suppress warning for any parameter of a dispatching
1196 -- operation, since it is quite reasonable to have an
1197 -- operation that is overridden, and for some subclasses
1198 -- needs the formal to be IN OUT and for others happens
1199 -- not to assign it.
1201 elsif Is_Dispatching_Operation
1202 (Scope (Goto_Spec_Entity (E1)))
1206 -- Suppress warning if composite type contains any access
1207 -- component, since the logical effect of modifying a
1208 -- parameter may be achieved by modifying a referenced
1211 elsif Is_Composite_Type (E1T)
1212 and then Has_Access_Values (E1T)
1216 -- Suppress warning on formals of an entry body. All
1217 -- references are attached to the formal in the entry
1218 -- declaration, which are marked Is_Entry_Formal.
1220 elsif Ekind (Scope (E1)) = E_Entry
1221 and then not Is_Entry_Formal (E1)
1225 -- OK, looks like warning for an IN OUT parameter that
1226 -- could be IN makes sense, but we delay the output of
1227 -- the warning, pending possibly finding out later on
1228 -- that the associated subprogram is used as a generic
1229 -- actual, or its address/access is taken. In these two
1230 -- cases, we suppress the warning because the context may
1231 -- force use of IN OUT, even if in this particular case
1232 -- the formal is not modified.
1235 In_Out_Warnings.Append (E1);
1238 -- Other cases of formals
1240 elsif Is_Formal (E1) then
1241 if not Is_Trivial_Subprogram (Scope (E1)) then
1242 if Referenced_Check_Spec (E1) then
1243 if not Has_Pragma_Unmodified_Check_Spec (E1)
1244 and then not Warnings_Off_E1
1246 Output_Reference_Error
1247 ("?f?formal parameter& is read but "
1248 & "never assigned!");
1251 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1252 and then not Warnings_Off_E1
1254 Output_Reference_Error
1255 ("?f?formal parameter& is not referenced!");
1262 if Referenced (E1) then
1263 if not Has_Unmodified (E1)
1264 and then not Warnings_Off_E1
1266 Output_Reference_Error
1267 ("?v?variable& is read but never assigned!");
1270 elsif not Has_Unreferenced (E1)
1271 and then not Warnings_Off_E1
1273 Output_Reference_Error -- CODEFIX
1274 ("?v?variable& is never read and never assigned!");
1277 -- Deal with special case where this variable is hidden
1278 -- by a loop variable.
1280 if Ekind (E1) = E_Variable
1281 and then Present (Hiding_Loop_Variable (E1))
1282 and then not Warnings_Off_E1
1285 ("?v?for loop implicitly declares loop variable!",
1286 Hiding_Loop_Variable (E1));
1288 Error_Msg_Sloc := Sloc (E1);
1290 ("\?v?declaration hides & declared#!",
1291 Hiding_Loop_Variable (E1));
1298 -- Check for unset reference
1300 if Warn_On_No_Value_Assigned and then Present (UR) then
1302 -- For other than access type, go back to original node to
1303 -- deal with case where original unset reference has been
1304 -- rewritten during expansion.
1306 -- In some cases, the original node may be a type conversion
1307 -- or qualification, and in this case we want the object
1310 UR := Original_Node (UR);
1311 while Nkind (UR) = N_Type_Conversion
1312 or else Nkind (UR) = N_Qualified_Expression
1313 or else Nkind (UR) = N_Expression_With_Actions
1315 UR := Expression (UR);
1318 -- Here we issue the warning, all checks completed
1320 -- If we have a return statement, this was a case of an OUT
1321 -- parameter not being set at the time of the return. (Note:
1322 -- it can't be N_Extended_Return_Statement, because those
1323 -- are only for functions, and functions do not allow OUT
1326 if not Is_Trivial_Subprogram (Scope (E1)) then
1327 if Nkind (UR) = N_Simple_Return_Statement
1328 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1330 if not Warnings_Off_E1 then
1332 ("?v?OUT parameter& not set before return",
1336 -- If the unset reference is a selected component
1337 -- prefix from source, mention the component as well.
1338 -- If the selected component comes from expansion, all
1339 -- we know is that the entity is not fully initialized
1340 -- at the point of the reference. Locate a random
1341 -- uninitialized component to get a better message.
1343 elsif Nkind (Parent (UR)) = N_Selected_Component then
1344 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1346 if not Comes_From_Source (Parent (UR)) then
1351 Comp := First_Entity (E1T);
1352 while Present (Comp) loop
1353 if Ekind (Comp) = E_Component
1354 and then Nkind (Parent (Comp)) =
1355 N_Component_Declaration
1356 and then No (Expression (Parent (Comp)))
1358 Error_Msg_Node_2 := Comp;
1367 -- Issue proper warning. This is a case of referencing
1368 -- a variable before it has been explicitly assigned.
1369 -- For access types, UR was only set for dereferences,
1370 -- so the issue is that the value may be null.
1372 if not Is_Trivial_Subprogram (Scope (E1)) then
1373 if not Warnings_Off_E1 then
1374 if Is_Access_Type (Etype (Parent (UR))) then
1375 Error_Msg_N ("?`&.&` may be null!", UR);
1378 ("?`&.&` may be referenced before "
1379 & "it has a value!", UR);
1384 -- All other cases of unset reference active
1386 elsif not Warnings_Off_E1 then
1388 ("?& may be referenced before it has a value!",
1397 -- Then check for unreferenced entities. Note that we are only
1398 -- interested in entities whose Referenced flag is not set.
1400 if not Referenced_Check_Spec (E1)
1402 -- If Referenced_As_LHS is set, then that's still interesting
1403 -- (potential "assigned but never read" case), but not if we
1404 -- have pragma Unreferenced, which cancels this warning.
1406 and then (not Referenced_As_LHS_Check_Spec (E1)
1407 or else not Has_Unreferenced (E1))
1409 -- Check that warnings on unreferenced entities are enabled
1412 ((Check_Unreferenced and then not Is_Formal (E1))
1414 -- Case of warning on unreferenced formal
1417 (Check_Unreferenced_Formals and then Is_Formal (E1))
1419 -- Case of warning on unread variables modified by an
1420 -- assignment, or an OUT parameter if it is the only one.
1423 (Warn_On_Modified_Unread
1424 and then Referenced_As_LHS_Check_Spec (E1))
1426 -- Case of warning on any unread OUT parameter (note
1427 -- such indications are only set if the appropriate
1428 -- warning options were set, so no need to recheck here.)
1431 Referenced_As_Out_Parameter_Check_Spec (E1))
1433 -- All other entities, including local packages that cannot be
1434 -- referenced from elsewhere, including those declared within a
1437 and then (Is_Object (E1)
1441 Ekind (E1) = E_Label
1443 Ekind (E1) = E_Exception
1445 Ekind (E1) = E_Named_Integer
1447 Ekind (E1) = E_Named_Real
1449 Is_Overloadable (E1)
1451 -- Package case, if the main unit is a package spec
1452 -- or generic package spec, then there may be a
1453 -- corresponding body that references this package
1454 -- in some other file. Otherwise we can be sure
1455 -- that there is no other reference.
1458 (Ekind (E1) = E_Package
1460 not Is_Package_Or_Generic_Package
1461 (Cunit_Entity (Current_Sem_Unit))))
1463 -- Exclude instantiations, since there is no reason why every
1464 -- entity in an instantiation should be referenced.
1466 and then Instantiation_Location (Sloc (E1)) = No_Location
1468 -- Exclude formal parameters from bodies if the corresponding
1469 -- spec entity has been referenced in the case where there is
1472 and then not (Is_Formal (E1)
1473 and then Ekind (Scope (E1)) = E_Subprogram_Body
1474 and then Present (Spec_Entity (E1))
1475 and then Referenced (Spec_Entity (E1)))
1477 -- Consider private type referenced if full view is referenced.
1478 -- If there is not full view, this is a generic type on which
1479 -- warnings are also useful.
1482 not (Is_Private_Type (E1)
1483 and then Present (Full_View (E1))
1484 and then Referenced (Full_View (E1)))
1486 -- Don't worry about full view, only about private type
1488 and then not Has_Private_Declaration (E1)
1490 -- Eliminate dispatching operations from consideration, we
1491 -- cannot tell if these are referenced or not in any easy
1492 -- manner (note this also catches Adjust/Finalize/Initialize).
1494 and then not Is_Dispatching_Operation (E1)
1496 -- Check entity that can be publicly referenced (we do not give
1497 -- messages for such entities, since there could be other
1498 -- units, not involved in this compilation, that contain
1499 -- relevant references.
1501 and then not Publicly_Referenceable (E1)
1503 -- Class wide types are marked as source entities, but they are
1504 -- not really source entities, and are always created, so we do
1505 -- not care if they are not referenced.
1507 and then Ekind (E1) /= E_Class_Wide_Type
1509 -- Objects other than parameters of task types are allowed to
1510 -- be non-referenced, since they start up tasks!
1512 and then ((Ekind (E1) /= E_Variable
1513 and then Ekind (E1) /= E_Constant
1514 and then Ekind (E1) /= E_Component)
1515 or else not Is_Task_Type (E1T))
1517 -- For subunits, only place warnings on the main unit itself,
1518 -- since parent units are not completely compiled.
1520 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1521 or else Get_Source_Unit (E1) = Main_Unit)
1523 -- No warning on a return object, because these are often
1524 -- created with a single expression and an implicit return.
1525 -- If the object is a variable there will be a warning
1526 -- indicating that it could be declared constant.
1529 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1531 -- Suppress warnings in internal units if not in -gnatg mode
1532 -- (these would be junk warnings for an applications program,
1533 -- since they refer to problems in internal units).
1536 or else not Is_Internal_File_Name
1537 (Unit_File_Name (Get_Source_Unit (E1)))
1539 -- We do not immediately flag the error. This is because we
1540 -- have not expanded generic bodies yet, and they may have
1541 -- the missing reference. So instead we park the entity on a
1542 -- list, for later processing. However for the case of an
1543 -- accept statement we want to output messages now, since
1544 -- we know we already have all information at hand, and we
1545 -- also want to have separate warnings for each accept
1546 -- statement for the same entry.
1548 if Present (Anod) then
1549 pragma Assert (Is_Formal (E1));
1551 -- The unreferenced entity is E1, but post the warning
1552 -- on the body entity for this accept statement.
1554 if not Warnings_Off_E1 then
1555 Warn_On_Unreferenced_Entity
1556 (E1, Body_Formal (E1, Accept_Statement => Anod));
1559 elsif not Warnings_Off_E1 then
1560 Unreferenced_Entities.Append (E1);
1564 -- Generic units are referenced in the generic body, but if they
1565 -- are not public and never instantiated we want to force a
1566 -- warning on them. We treat them as redundant constructs to
1569 elsif Is_Generic_Subprogram (E1)
1570 and then not Is_Instantiated (E1)
1571 and then not Publicly_Referenceable (E1)
1572 and then Instantiation_Depth (Sloc (E1)) = 0
1573 and then Warn_On_Redundant_Constructs
1575 if not Warnings_Off_E1 then
1576 Unreferenced_Entities.Append (E1);
1578 -- Force warning on entity
1580 Set_Referenced (E1, False);
1585 -- Recurse into nested package or block. Do not recurse into a formal
1586 -- package, because the corresponding body is not analyzed.
1589 if (Is_Package_Or_Generic_Package (E1)
1590 and then Nkind (Parent (E1)) = N_Package_Specification
1592 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1593 /= N_Formal_Package_Declaration)
1595 or else Ekind (E1) = E_Block
1597 Check_References (E1);
1602 end Check_References;
1604 ---------------------------
1605 -- Check_Unset_Reference --
1606 ---------------------------
1608 procedure Check_Unset_Reference (N : Node_Id) is
1609 Typ : constant Entity_Id := Etype (N);
1611 function Is_OK_Fully_Initialized return Boolean;
1612 -- This function returns true if the given node N is fully initialized
1613 -- so that the reference is safe as far as this routine is concerned.
1614 -- Safe generally means that the type of N is a fully initialized type.
1615 -- The one special case is that for access types, which are always fully
1616 -- initialized, we don't consider a dereference OK since it will surely
1617 -- be dereferencing a null value, which won't do.
1619 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1620 -- Used to test indexed or selected component or slice to see if the
1621 -- evaluation of the prefix depends on a dereference, and if so, returns
1622 -- True, in which case we always check the prefix, even if we know that
1623 -- the referenced component is initialized. Pref is the prefix to test.
1625 -----------------------------
1626 -- Is_OK_Fully_Initialized --
1627 -----------------------------
1629 function Is_OK_Fully_Initialized return Boolean is
1631 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1634 return Is_Fully_Initialized_Type (Typ);
1636 end Is_OK_Fully_Initialized;
1638 ----------------------------
1639 -- Prefix_Has_Dereference --
1640 ----------------------------
1642 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1644 -- If prefix is of an access type, it certainly needs a dereference
1646 if Is_Access_Type (Etype (Pref)) then
1649 -- If prefix is explicit dereference, that's a dereference for sure
1651 elsif Nkind (Pref) = N_Explicit_Dereference then
1654 -- If prefix is itself a component reference or slice check prefix
1656 elsif Nkind (Pref) = N_Slice
1657 or else Nkind (Pref) = N_Indexed_Component
1658 or else Nkind (Pref) = N_Selected_Component
1660 return Prefix_Has_Dereference (Prefix (Pref));
1662 -- All other cases do not involve a dereference
1667 end Prefix_Has_Dereference;
1669 -- Start of processing for Check_Unset_Reference
1672 -- Nothing to do if warnings suppressed
1674 if Warning_Mode = Suppress then
1678 -- Nothing to do for numeric or string literal. Do this test early to
1679 -- save time in a common case (it does not matter that we do not include
1680 -- character literal here, since that will be caught later on in the
1681 -- when others branch of the case statement).
1683 if Nkind (N) in N_Numeric_Or_String_Literal then
1687 -- Ignore reference unless it comes from source. Almost always if we
1688 -- have a reference from generated code, it is bogus (e.g. calls to init
1689 -- procs to set default discriminant values).
1691 if not Comes_From_Source (N) then
1695 -- Otherwise see what kind of node we have. If the entity already has an
1696 -- unset reference, it is not necessarily the earliest in the text,
1697 -- because resolution of the prefix of selected components is completed
1698 -- before the resolution of the selected component itself. As a result,
1699 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1700 -- in right-to-left order. If there is already an unset reference, we
1701 -- check whether N is earlier before proceeding.
1705 -- For identifier or expanded name, examine the entity involved
1707 when N_Identifier | N_Expanded_Name =>
1709 E : constant Entity_Id := Entity (N);
1712 if (Ekind (E) = E_Variable
1714 Ekind (E) = E_Out_Parameter)
1715 and then Never_Set_In_Source_Check_Spec (E)
1716 and then not Has_Initial_Value (E)
1717 and then (No (Unset_Reference (E))
1719 Earlier_In_Extended_Unit
1720 (Sloc (N), Sloc (Unset_Reference (E))))
1721 and then not Has_Pragma_Unmodified_Check_Spec (E)
1722 and then not Warnings_Off_Check_Spec (E)
1724 -- We may have an unset reference. The first test is whether
1725 -- this is an access to a discriminant of a record or a
1726 -- component with default initialization. Both of these
1727 -- cases can be ignored, since the actual object that is
1728 -- referenced is definitely initialized. Note that this
1729 -- covers the case of reading discriminants of an OUT
1730 -- parameter, which is OK even in Ada 83.
1732 -- Note that we are only interested in a direct reference to
1733 -- a record component here. If the reference is through an
1734 -- access type, then the access object is being referenced,
1735 -- not the record, and still deserves an unset reference.
1737 if Nkind (Parent (N)) = N_Selected_Component
1738 and not Is_Access_Type (Typ)
1741 ES : constant Entity_Id :=
1742 Entity (Selector_Name (Parent (N)));
1744 if Ekind (ES) = E_Discriminant
1746 (Present (Declaration_Node (ES))
1748 Present (Expression (Declaration_Node (ES))))
1755 -- Exclude fully initialized types
1757 if Is_OK_Fully_Initialized then
1761 -- Here we have a potential unset reference. But before we
1762 -- get worried about it, we have to make sure that the
1763 -- entity declaration is in the same procedure as the
1764 -- reference, since if they are in separate procedures, then
1765 -- we have no idea about sequential execution.
1767 -- The tests in the loop below catch all such cases, but do
1768 -- allow the reference to appear in a loop, block, or
1769 -- package spec that is nested within the declaring scope.
1770 -- As always, it is possible to construct cases where the
1771 -- warning is wrong, that is why it is a warning!
1773 Potential_Unset_Reference : declare
1775 SE : constant Entity_Id := Scope (E);
1777 function Within_Postcondition return Boolean;
1778 -- Returns True iff N is within a Postcondition, an
1779 -- Ensures component in a Test_Case, or a Contract_Cases.
1781 --------------------------
1782 -- Within_Postcondition --
1783 --------------------------
1785 function Within_Postcondition return Boolean is
1790 while Present (Nod) loop
1791 if Nkind (Nod) = N_Pragma
1792 and then Nam_In (Pragma_Name (Nod),
1794 Name_Contract_Cases)
1798 elsif Present (Parent (Nod)) then
1801 if Nkind (P) = N_Pragma
1803 Pragma_Name (P) = Name_Test_Case
1805 Nod = Get_Ensures_From_CTC_Pragma (P)
1811 Nod := Parent (Nod);
1815 end Within_Postcondition;
1817 -- Start of processing for Potential_Unset_Reference
1820 SR := Current_Scope;
1822 if SR = Standard_Standard
1823 or else Is_Subprogram (SR)
1824 or else Is_Concurrent_Body (SR)
1825 or else Is_Concurrent_Type (SR)
1833 -- Case of reference has an access type. This is a
1834 -- special case since access types are always set to null
1835 -- so cannot be truly uninitialized, but we still want to
1836 -- warn about cases of obvious null dereference.
1838 if Is_Access_Type (Typ) then
1839 Access_Type_Case : declare
1843 (N : Node_Id) return Traverse_Result;
1844 -- Process function for instantiation of Traverse
1845 -- below. Checks if N contains reference to E other
1846 -- than a dereference.
1848 function Ref_In (Nod : Node_Id) return Boolean;
1849 -- Determines whether Nod contains a reference to
1850 -- the entity E that is not a dereference.
1857 (N : Node_Id) return Traverse_Result
1860 if Is_Entity_Name (N)
1861 and then Entity (N) = E
1862 and then not Is_Dereferenced (N)
1874 function Ref_In (Nod : Node_Id) return Boolean is
1875 function Traverse is new Traverse_Func (Process);
1877 return Traverse (Nod) = Abandon;
1880 -- Start of processing for Access_Type_Case
1883 -- Don't bother if we are inside an instance, since
1884 -- the compilation of the generic template is where
1885 -- the warning should be issued.
1891 -- Don't bother if this is not the main unit. If we
1892 -- try to give this warning for with'ed units, we
1893 -- get some false positives, since we do not record
1894 -- references in other units.
1896 if not In_Extended_Main_Source_Unit (E)
1898 not In_Extended_Main_Source_Unit (N)
1903 -- We are only interested in dereferences
1905 if not Is_Dereferenced (N) then
1909 -- One more check, don't bother with references
1910 -- that are inside conditional statements or WHILE
1911 -- loops if the condition references the entity in
1912 -- question. This avoids most false positives.
1919 if (Nkind (P) = N_If_Statement
1921 Nkind (P) = N_Elsif_Part)
1922 and then Ref_In (Condition (P))
1926 elsif Nkind (P) = N_Loop_Statement
1927 and then Present (Iteration_Scheme (P))
1929 Ref_In (Condition (Iteration_Scheme (P)))
1934 end Access_Type_Case;
1937 -- One more check, don't bother if we are within a
1938 -- postcondition, since the expression occurs in a
1939 -- place unrelated to the actual test.
1941 if not Within_Postcondition then
1943 -- Here we definitely have a case for giving a warning
1944 -- for a reference to an unset value. But we don't
1945 -- give the warning now. Instead set Unset_Reference
1946 -- in the identifier involved. The reason for this is
1947 -- that if we find the variable is never ever assigned
1948 -- a value then that warning is more important and
1949 -- there is no point in giving the reference warning.
1951 -- If this is an identifier, set the field directly
1953 if Nkind (N) = N_Identifier then
1954 Set_Unset_Reference (E, N);
1956 -- Otherwise it is an expanded name, so set the field
1957 -- of the actual identifier for the reference.
1960 Set_Unset_Reference (E, Selector_Name (N));
1963 end Potential_Unset_Reference;
1967 -- Indexed component or slice
1969 when N_Indexed_Component | N_Slice =>
1971 -- If prefix does not involve dereferencing an access type, then
1972 -- we know we are OK if the component type is fully initialized,
1973 -- since the component will have been set as part of the default
1976 if not Prefix_Has_Dereference (Prefix (N))
1977 and then Is_OK_Fully_Initialized
1981 -- Look at prefix in access type case, or if the component is not
1982 -- fully initialized.
1985 Check_Unset_Reference (Prefix (N));
1990 when N_Selected_Component =>
1992 Pref : constant Node_Id := Prefix (N);
1993 Ent : constant Entity_Id := Entity (Selector_Name (N));
1996 -- If prefix involves dereferencing an access type, always
1997 -- check the prefix, since the issue then is whether this
1998 -- access value is null.
2000 if Prefix_Has_Dereference (Pref) then
2003 -- Always go to prefix if no selector entity is set. Can this
2004 -- happen in the normal case? Not clear, but it definitely can
2005 -- happen in error cases.
2010 -- For a record component, check some cases where we have
2011 -- reasonable cause to consider that the component is known to
2012 -- be or probably is initialized. In this case, we don't care
2013 -- if the prefix itself was explicitly initialized.
2015 -- Discriminants are always considered initialized
2017 elsif Ekind (Ent) = E_Discriminant then
2020 -- An explicitly initialized component is certainly initialized
2022 elsif Nkind (Parent (Ent)) = N_Component_Declaration
2023 and then Present (Expression (Parent (Ent)))
2027 -- A fully initialized component is initialized
2029 elsif Is_OK_Fully_Initialized then
2033 -- If none of those cases apply, check the record type prefix
2035 Check_Unset_Reference (Pref);
2038 -- For type conversions, qualifications, or expressions with actions,
2039 -- examine the expression.
2041 when N_Type_Conversion |
2042 N_Qualified_Expression |
2043 N_Expression_With_Actions =>
2044 Check_Unset_Reference (Expression (N));
2046 -- For explicit dereference, always check prefix, which will generate
2047 -- an unset reference (since this is a case of dereferencing null).
2049 when N_Explicit_Dereference =>
2050 Check_Unset_Reference (Prefix (N));
2052 -- All other cases are not cases of an unset reference
2058 end Check_Unset_Reference;
2060 ------------------------
2061 -- Check_Unused_Withs --
2062 ------------------------
2064 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2070 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2071 -- This is needed for checking the special renaming case
2073 procedure Check_One_Unit (Unit : Unit_Number_Type);
2074 -- Subsidiary procedure, performs checks for specified unit
2076 --------------------
2077 -- Check_One_Unit --
2078 --------------------
2080 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2081 Is_Visible_Renaming : Boolean := False;
2084 procedure Check_Inner_Package (Pack : Entity_Id);
2085 -- Pack is a package local to a unit in a with_clause. Both the unit
2086 -- and Pack are referenced. If none of the entities in Pack are
2087 -- referenced, then the only occurrence of Pack is in a USE clause
2088 -- or a pragma, and a warning is worthwhile as well.
2090 function Check_System_Aux return Boolean;
2091 -- Before giving a warning on a with_clause for System, check whether
2092 -- a system extension is present.
2094 function Find_Package_Renaming
2096 L : Entity_Id) return Entity_Id;
2097 -- The only reference to a context unit may be in a renaming
2098 -- declaration. If this renaming declares a visible entity, do not
2099 -- warn that the context clause could be moved to the body, because
2100 -- the renaming may be intended to re-export the unit.
2102 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2103 -- This function determines if a package has any visible entities.
2104 -- True is returned if there is at least one declared visible entity,
2105 -- otherwise False is returned (e.g. case of only pragmas present).
2107 -------------------------
2108 -- Check_Inner_Package --
2109 -------------------------
2111 procedure Check_Inner_Package (Pack : Entity_Id) is
2113 Un : constant Node_Id := Sinfo.Unit (Cnode);
2115 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2116 -- If N is a use_clause for Pack, emit warning
2118 procedure Check_Use_Clauses is new
2119 Traverse_Proc (Check_Use_Clause);
2121 ----------------------
2122 -- Check_Use_Clause --
2123 ----------------------
2125 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2129 if Nkind (N) = N_Use_Package_Clause then
2130 Nam := First (Names (N));
2131 while Present (Nam) loop
2132 if Entity (Nam) = Pack then
2133 Error_Msg_Qual_Level := 1;
2134 Error_Msg_NE -- CODEFIX
2135 ("?u?no entities of package& are referenced!",
2137 Error_Msg_Qual_Level := 0;
2145 end Check_Use_Clause;
2147 -- Start of processing for Check_Inner_Package
2150 E := First_Entity (Pack);
2151 while Present (E) loop
2152 if Referenced_Check_Spec (E) then
2159 -- No entities of the package are referenced. Check whether the
2160 -- reference to the package itself is a use clause, and if so
2161 -- place a warning on it.
2163 Check_Use_Clauses (Un);
2164 end Check_Inner_Package;
2166 ----------------------
2167 -- Check_System_Aux --
2168 ----------------------
2170 function Check_System_Aux return Boolean is
2174 if Chars (Lunit) = Name_System
2175 and then Scope (Lunit) = Standard_Standard
2176 and then Present_System_Aux
2178 Ent := First_Entity (System_Aux_Id);
2179 while Present (Ent) loop
2180 if Referenced_Check_Spec (Ent) then
2189 end Check_System_Aux;
2191 ---------------------------
2192 -- Find_Package_Renaming --
2193 ---------------------------
2195 function Find_Package_Renaming
2197 L : Entity_Id) return Entity_Id
2203 Is_Visible_Renaming := False;
2205 E1 := First_Entity (P);
2206 while Present (E1) loop
2207 if Ekind (E1) = E_Package
2208 and then Renamed_Object (E1) = L
2210 Is_Visible_Renaming := not Is_Hidden (E1);
2213 elsif Ekind (E1) = E_Package
2214 and then No (Renamed_Object (E1))
2215 and then not Is_Generic_Instance (E1)
2217 R := Find_Package_Renaming (E1, L);
2220 Is_Visible_Renaming := not Is_Hidden (R);
2229 end Find_Package_Renaming;
2231 --------------------------
2232 -- Has_Visible_Entities --
2233 --------------------------
2235 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2239 -- If unit in context is not a package, it is a subprogram that
2240 -- is not called or a generic unit that is not instantiated
2241 -- in the current unit, and warning is appropriate.
2243 if Ekind (P) /= E_Package then
2247 -- If unit comes from a limited_with clause, look for declaration
2248 -- of shadow entities.
2250 if Present (Limited_View (P)) then
2251 E := First_Entity (Limited_View (P));
2253 E := First_Entity (P);
2257 and then E /= First_Private_Entity (P)
2259 if Comes_From_Source (E)
2260 or else Present (Limited_View (P))
2269 end Has_Visible_Entities;
2271 -- Start of processing for Check_One_Unit
2274 Cnode := Cunit (Unit);
2276 -- Only do check in units that are part of the extended main unit.
2277 -- This is actually a necessary restriction, because in the case of
2278 -- subprogram acting as its own specification, there can be with's in
2279 -- subunits that we will not see.
2281 if not In_Extended_Main_Source_Unit (Cnode) then
2284 -- In configurable run time mode, we remove the bodies of non-inlined
2285 -- subprograms, which may lead to spurious warnings, which are
2286 -- clearly undesirable.
2288 elsif Configurable_Run_Time_Mode
2289 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2294 -- Loop through context items in this unit
2296 Item := First (Context_Items (Cnode));
2297 while Present (Item) loop
2298 if Nkind (Item) = N_With_Clause
2299 and then not Implicit_With (Item)
2300 and then In_Extended_Main_Source_Unit (Item)
2302 Lunit := Entity (Name (Item));
2304 -- Check if this unit is referenced (skip the check if this
2305 -- is explicitly marked by a pragma Unreferenced).
2307 if not Referenced (Lunit)
2308 and then not Has_Unreferenced (Lunit)
2310 -- Suppress warnings in internal units if not in -gnatg mode
2311 -- (these would be junk warnings for an application program,
2312 -- since they refer to problems in internal units).
2315 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2317 -- Here we definitely have a non-referenced unit. If it
2318 -- is the special call for a spec unit, then just set the
2319 -- flag to be read later.
2321 if Unit = Spec_Unit then
2322 Set_Unreferenced_In_Spec (Item);
2324 -- Otherwise simple unreferenced message, but skip this
2325 -- if no visible entities, because that is most likely a
2326 -- case where warning would be false positive (e.g. a
2327 -- package with only a linker options pragma and nothing
2328 -- else or a pragma elaborate with a body library task).
2330 elsif Has_Visible_Entities (Entity (Name (Item))) then
2331 Error_Msg_N -- CODEFIX
2332 ("?u?unit& is not referenced!", Name (Item));
2336 -- If main unit is a renaming of this unit, then we consider
2337 -- the with to be OK (obviously it is needed in this case!)
2338 -- This may be transitive: the unit in the with_clause may
2339 -- itself be a renaming, in which case both it and the main
2340 -- unit rename the same ultimate package.
2342 elsif Present (Renamed_Entity (Munite))
2344 (Renamed_Entity (Munite) = Lunit
2345 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2349 -- If this unit is referenced, and it is a package, we do
2350 -- another test, to see if any of the entities in the package
2351 -- are referenced. If none of the entities are referenced, we
2352 -- still post a warning. This occurs if the only use of the
2353 -- package is in a use clause, or in a package renaming
2354 -- declaration. This check is skipped for packages that are
2355 -- renamed in a spec, since the entities in such a package are
2356 -- visible to clients via the renaming.
2358 elsif Ekind (Lunit) = E_Package
2359 and then not Renamed_In_Spec (Lunit)
2361 -- If Is_Instantiated is set, it means that the package is
2362 -- implicitly instantiated (this is the case of parent
2363 -- instance or an actual for a generic package formal), and
2364 -- this counts as a reference.
2366 if Is_Instantiated (Lunit) then
2369 -- If no entities in package, and there is a pragma
2370 -- Elaborate_Body present, then assume that this with is
2371 -- done for purposes of this elaboration.
2373 elsif No (First_Entity (Lunit))
2374 and then Has_Pragma_Elaborate_Body (Lunit)
2378 -- Otherwise see if any entities have been referenced
2381 if Limited_Present (Item) then
2382 Ent := First_Entity (Limited_View (Lunit));
2384 Ent := First_Entity (Lunit);
2388 -- No more entities, and we did not find one that was
2389 -- referenced. Means we have a definite case of a with
2390 -- none of whose entities was referenced.
2394 -- If in spec, just set the flag
2396 if Unit = Spec_Unit then
2397 Set_No_Entities_Ref_In_Spec (Item);
2399 elsif Check_System_Aux then
2402 -- Else give the warning
2406 Has_Unreferenced (Entity (Name (Item)))
2408 Error_Msg_N -- CODEFIX
2409 ("?u?no entities of & are referenced!",
2413 -- Look for renamings of this package, and flag
2414 -- them as well. If the original package has
2415 -- warnings off, we suppress the warning on the
2416 -- renaming as well.
2418 Pack := Find_Package_Renaming (Munite, Lunit);
2421 and then not Has_Warnings_Off (Lunit)
2422 and then not Has_Unreferenced (Pack)
2424 Error_Msg_NE -- CODEFIX
2425 ("?u?no entities of & are referenced!",
2426 Unit_Declaration_Node (Pack),
2433 -- Case of entity being referenced. The reference may
2434 -- come from a limited_with_clause, in which case the
2435 -- limited view of the entity carries the flag.
2437 elsif Referenced_Check_Spec (Ent)
2438 or else Referenced_As_LHS_Check_Spec (Ent)
2439 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2441 (From_Limited_With (Ent)
2442 and then Is_Incomplete_Type (Ent)
2443 and then Present (Non_Limited_View (Ent))
2444 and then Referenced (Non_Limited_View (Ent)))
2446 -- This means that the with is indeed fine, in that
2447 -- it is definitely needed somewhere, and we can
2448 -- quit worrying about this one...
2450 -- Except for one little detail: if either of the
2451 -- flags was set during spec processing, this is
2452 -- where we complain that the with could be moved
2453 -- from the spec. If the spec contains a visible
2454 -- renaming of the package, inhibit warning to move
2455 -- with_clause to body.
2457 if Ekind (Munite) = E_Package_Body then
2459 Find_Package_Renaming
2460 (Spec_Entity (Munite), Lunit);
2465 -- If a renaming is present in the spec do not warn
2466 -- because the body or child unit may depend on it.
2469 and then Renamed_Entity (Pack) = Lunit
2473 elsif Unreferenced_In_Spec (Item) then
2474 Error_Msg_N -- CODEFIX
2475 ("?u?unit& is not referenced in spec!",
2478 elsif No_Entities_Ref_In_Spec (Item) then
2479 Error_Msg_N -- CODEFIX
2480 ("?u?no entities of & are referenced in spec!",
2484 if Ekind (Ent) = E_Package then
2485 Check_Inner_Package (Ent);
2491 if not Is_Visible_Renaming then
2492 Error_Msg_N -- CODEFIX
2493 ("\?u?with clause might be moved to body!",
2499 -- Move to next entity to continue search
2507 -- For a generic package, the only interesting kind of
2508 -- reference is an instantiation, since entities cannot be
2509 -- referenced directly.
2511 elsif Is_Generic_Unit (Lunit) then
2513 -- Unit was never instantiated, set flag for case of spec
2514 -- call, or give warning for normal call.
2516 if not Is_Instantiated (Lunit) then
2517 if Unit = Spec_Unit then
2518 Set_Unreferenced_In_Spec (Item);
2520 Error_Msg_N -- CODEFIX
2521 ("?u?unit& is never instantiated!", Name (Item));
2524 -- If unit was indeed instantiated, make sure that flag is
2525 -- not set showing it was uninstantiated in the spec, and if
2526 -- so, give warning.
2528 elsif Unreferenced_In_Spec (Item) then
2530 ("?u?unit& is not instantiated in spec!", Name (Item));
2531 Error_Msg_N -- CODEFIX
2532 ("\?u?with clause can be moved to body!", Name (Item));
2541 -- Start of processing for Check_Unused_Withs
2544 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then
2548 -- Flag any unused with clauses, but skip this step if we are compiling
2549 -- a subunit on its own, since we do not have enough information to
2550 -- determine whether with's are used. We will get the relevant warnings
2551 -- when we compile the parent. This is the normal style of GNAT
2552 -- compilation in any case.
2554 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2558 -- Process specified units
2560 if Spec_Unit = No_Unit then
2562 -- For main call, check all units
2564 for Unit in Main_Unit .. Last_Unit loop
2565 Check_One_Unit (Unit);
2569 -- For call for spec, check only the spec
2571 Check_One_Unit (Spec_Unit);
2573 end Check_Unused_Withs;
2575 ---------------------------------
2576 -- Generic_Package_Spec_Entity --
2577 ---------------------------------
2579 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2583 if Is_Package_Body_Entity (E) then
2589 if S = Standard_Standard then
2592 elsif Ekind (S) = E_Generic_Package then
2595 elsif Ekind (S) = E_Package then
2603 end Generic_Package_Spec_Entity;
2605 ----------------------
2606 -- Goto_Spec_Entity --
2607 ----------------------
2609 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2612 and then Present (Spec_Entity (E))
2614 return Spec_Entity (E);
2618 end Goto_Spec_Entity;
2620 --------------------------------------
2621 -- Has_Pragma_Unmodified_Check_Spec --
2622 --------------------------------------
2624 function Has_Pragma_Unmodified_Check_Spec
2625 (E : Entity_Id) return Boolean
2628 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2630 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2631 -- to mess with Unmodified flags on both body and spec entities.
2633 return Has_Unmodified (E)
2635 Has_Unmodified (Spec_Entity (E));
2638 return Has_Unmodified (E);
2640 end Has_Pragma_Unmodified_Check_Spec;
2642 ----------------------------------------
2643 -- Has_Pragma_Unreferenced_Check_Spec --
2644 ----------------------------------------
2646 function Has_Pragma_Unreferenced_Check_Spec
2647 (E : Entity_Id) return Boolean
2650 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2652 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2653 -- to mess with flags on both entities.
2655 return Has_Unreferenced (E)
2657 Has_Unreferenced (Spec_Entity (E));
2660 return Has_Unreferenced (E);
2662 end Has_Pragma_Unreferenced_Check_Spec;
2668 procedure Initialize is
2670 Warnings_Off_Pragmas.Init;
2671 Unreferenced_Entities.Init;
2672 In_Out_Warnings.Init;
2675 ------------------------------------
2676 -- Never_Set_In_Source_Check_Spec --
2677 ------------------------------------
2679 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2681 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2682 return Never_Set_In_Source (E)
2684 Never_Set_In_Source (Spec_Entity (E));
2686 return Never_Set_In_Source (E);
2688 end Never_Set_In_Source_Check_Spec;
2690 -------------------------------------
2691 -- Operand_Has_Warnings_Suppressed --
2692 -------------------------------------
2694 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2696 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2697 -- Function used to check one node to see if it is or was originally
2698 -- a reference to an entity for which Warnings are off. If so, Abandon
2699 -- is returned, otherwise OK_Orig is returned to continue the traversal
2700 -- of the original expression.
2702 function Traverse is new Traverse_Func (Check_For_Warnings);
2703 -- Function used to traverse tree looking for warnings
2705 ------------------------
2706 -- Check_For_Warnings --
2707 ------------------------
2709 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2710 R : constant Node_Id := Original_Node (N);
2713 if Nkind (R) in N_Has_Entity
2714 and then Present (Entity (R))
2715 and then Has_Warnings_Off (Entity (R))
2721 end Check_For_Warnings;
2723 -- Start of processing for Operand_Has_Warnings_Suppressed
2726 return Traverse (N) = Abandon;
2728 -- If any exception occurs, then something has gone wrong, and this is
2729 -- only a minor aesthetic issue anyway, so just say we did not find what
2730 -- we are looking for, rather than blow up.
2735 end Operand_Has_Warnings_Suppressed;
2737 -----------------------------------------
2738 -- Output_Non_Modified_In_Out_Warnings --
2739 -----------------------------------------
2741 procedure Output_Non_Modified_In_Out_Warnings is
2743 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2744 -- Given a formal parameter entity E, determines if there is a reason to
2745 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2746 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2747 -- if we have seen the address of the subprogram being taken, or if the
2748 -- subprogram is used as a generic actual (in the latter cases the
2749 -- context may force use of IN OUT, even if the parameter is not
2750 -- modifies for this particular case.
2752 -----------------------
2753 -- No_Warn_On_In_Out --
2754 -----------------------
2756 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2757 S : constant Entity_Id := Scope (E);
2758 SE : constant Entity_Id := Spec_Entity (E);
2761 -- Do not warn if address is taken, since funny business may be going
2762 -- on in treating the parameter indirectly as IN OUT.
2764 if Address_Taken (S)
2765 or else (Present (SE) and then Address_Taken (Scope (SE)))
2769 -- Do not warn if used as a generic actual, since the generic may be
2770 -- what is forcing the use of an "unnecessary" IN OUT.
2772 elsif Used_As_Generic_Actual (S)
2773 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2777 -- Else test warnings off
2779 elsif Warnings_Off_Check_Spec (S) then
2782 -- All tests for suppressing warning failed
2787 end No_Warn_On_In_Out;
2789 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2792 -- Loop through entities for which a warning may be needed
2794 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2796 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2799 -- Suppress warning in specific cases (see details in comments for
2800 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2802 if Has_Pragma_Unmodified_Check_Spec (E1)
2803 or else No_Warn_On_In_Out (E1)
2807 -- Here we generate the warning
2810 -- If -gnatwc is set then output message that we could be IN
2812 if not Is_Trivial_Subprogram (Scope (E1)) then
2813 if Warn_On_Constant then
2815 ("?u?formal parameter & is not modified!", E1);
2817 ("\?u?mode could be IN instead of `IN OUT`!", E1);
2819 -- We do not generate warnings for IN OUT parameters
2820 -- unless we have at least -gnatwu. This is deliberately
2821 -- inconsistent with the treatment of variables, but
2822 -- otherwise we get too many unexpected warnings in
2825 elsif Check_Unreferenced then
2827 ("?u?formal parameter& is read but "
2828 & "never assigned!", E1);
2832 -- Kill any other warnings on this entity, since this is the
2833 -- one that should dominate any other unreferenced warning.
2835 Set_Warnings_Off (E1);
2839 end Output_Non_Modified_In_Out_Warnings;
2841 ----------------------------------------
2842 -- Output_Obsolescent_Entity_Warnings --
2843 ----------------------------------------
2845 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2846 P : constant Node_Id := Parent (N);
2852 -- Do not output message if we are the scope of standard. This means
2853 -- we have a reference from a context clause from when it is originally
2854 -- processed, and that's too early to tell whether it is an obsolescent
2855 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2856 -- sure that we have a later call when the scope is available. This test
2857 -- also eliminates all messages for use clauses, which is fine (we do
2858 -- not want messages for use clauses, since they are always redundant
2859 -- with respect to the associated with clause).
2861 if S = Standard_Standard then
2865 -- Do not output message if we are in scope of an obsolescent package
2869 if Is_Obsolescent (S) then
2874 exit when S = Standard_Standard;
2877 -- Here we will output the message
2879 Error_Msg_Sloc := Sloc (E);
2881 -- Case of with clause
2883 if Nkind (P) = N_With_Clause then
2884 if Ekind (E) = E_Package then
2886 ("??with of obsolescent package& declared#", N, E);
2887 elsif Ekind (E) = E_Procedure then
2889 ("??with of obsolescent procedure& declared#", N, E);
2892 ("??with of obsolescent function& declared#", N, E);
2895 -- If we do not have a with clause, then ignore any reference to an
2896 -- obsolescent package name. We only want to give the one warning of
2897 -- withing the package, not one each time it is used to qualify.
2899 elsif Ekind (E) = E_Package then
2902 -- Procedure call statement
2904 elsif Nkind (P) = N_Procedure_Call_Statement then
2906 ("??call to obsolescent procedure& declared#", N, E);
2910 elsif Nkind (P) = N_Function_Call then
2912 ("??call to obsolescent function& declared#", N, E);
2914 -- Reference to obsolescent type
2916 elsif Is_Type (E) then
2918 ("??reference to obsolescent type& declared#", N, E);
2920 -- Reference to obsolescent component
2922 elsif Ekind_In (E, E_Component, E_Discriminant) then
2924 ("??reference to obsolescent component& declared#", N, E);
2926 -- Reference to obsolescent variable
2928 elsif Ekind (E) = E_Variable then
2930 ("??reference to obsolescent variable& declared#", N, E);
2932 -- Reference to obsolescent constant
2934 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then
2936 ("??reference to obsolescent constant& declared#", N, E);
2938 -- Reference to obsolescent enumeration literal
2940 elsif Ekind (E) = E_Enumeration_Literal then
2942 ("??reference to obsolescent enumeration literal& declared#", N, E);
2944 -- Generic message for any other case we missed
2948 ("??reference to obsolescent entity& declared#", N, E);
2951 -- Output additional warning if present
2953 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2954 if Obsolescent_Warnings.Table (J).Ent = E then
2955 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2956 Error_Msg_Strlen := Name_Len;
2957 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2958 Error_Msg_N ("\\??~", N);
2962 end Output_Obsolescent_Entity_Warnings;
2964 ----------------------------------
2965 -- Output_Unreferenced_Messages --
2966 ----------------------------------
2968 procedure Output_Unreferenced_Messages is
2970 for J in Unreferenced_Entities.First ..
2971 Unreferenced_Entities.Last
2973 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2975 end Output_Unreferenced_Messages;
2977 -----------------------------------------
2978 -- Output_Unused_Warnings_Off_Warnings --
2979 -----------------------------------------
2981 procedure Output_Unused_Warnings_Off_Warnings is
2983 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2985 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2986 N : Node_Id renames Wentry.N;
2987 E : Node_Id renames Wentry.E;
2990 -- Turn off Warnings_Off, or we won't get the warning!
2992 Set_Warnings_Off (E, False);
2994 -- Nothing to do if pragma was used to suppress a general warning
2996 if Warnings_Off_Used (E) then
2999 -- If pragma was used both in unmodified and unreferenced contexts
3000 -- then that's as good as the general case, no warning.
3002 elsif Warnings_Off_Used_Unmodified (E)
3004 Warnings_Off_Used_Unreferenced (E)
3008 -- Used only in context where Unmodified would have worked
3010 elsif Warnings_Off_Used_Unmodified (E) then
3012 ("?W?could use Unmodified instead of "
3013 & "Warnings Off for &", Pragma_Identifier (N), E);
3015 -- Used only in context where Unreferenced would have worked
3017 elsif Warnings_Off_Used_Unreferenced (E) then
3019 ("?W?could use Unreferenced instead of "
3020 & "Warnings Off for &", Pragma_Identifier (N), E);
3026 ("?W?pragma Warnings Off for & unused, "
3027 & "could be omitted", N, E);
3031 end Output_Unused_Warnings_Off_Warnings;
3033 ---------------------------
3034 -- Referenced_Check_Spec --
3035 ---------------------------
3037 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3039 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3040 return Referenced (E) or else Referenced (Spec_Entity (E));
3042 return Referenced (E);
3044 end Referenced_Check_Spec;
3046 ----------------------------------
3047 -- Referenced_As_LHS_Check_Spec --
3048 ----------------------------------
3050 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3052 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3053 return Referenced_As_LHS (E)
3054 or else Referenced_As_LHS (Spec_Entity (E));
3056 return Referenced_As_LHS (E);
3058 end Referenced_As_LHS_Check_Spec;
3060 --------------------------------------------
3061 -- Referenced_As_Out_Parameter_Check_Spec --
3062 --------------------------------------------
3064 function Referenced_As_Out_Parameter_Check_Spec
3065 (E : Entity_Id) return Boolean
3068 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3069 return Referenced_As_Out_Parameter (E)
3070 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3072 return Referenced_As_Out_Parameter (E);
3074 end Referenced_As_Out_Parameter_Check_Spec;
3076 -----------------------------
3077 -- Warn_On_Known_Condition --
3078 -----------------------------
3080 procedure Warn_On_Known_Condition (C : Node_Id) is
3082 Orig : constant Node_Id := Original_Node (C);
3083 Test_Result : Boolean;
3085 function Is_Known_Branch return Boolean;
3086 -- If the type of the condition is Boolean, the constant value of the
3087 -- condition is a boolean literal. If the type is a derived boolean
3088 -- type, the constant is wrapped in a type conversion of the derived
3089 -- literal. If the value of the condition is not a literal, no warnings
3090 -- can be produced. This function returns True if the result can be
3091 -- determined, and Test_Result is set True/False accordingly. Otherwise
3092 -- False is returned, and Test_Result is unchanged.
3094 procedure Track (N : Node_Id; Loc : Node_Id);
3095 -- Adds continuation warning(s) pointing to reason (assignment or test)
3096 -- for the operand of the conditional having a known value (or at least
3097 -- enough is known about the value to issue the warning). N is the node
3098 -- which is judged to have a known value. Loc is the warning location.
3100 ---------------------
3101 -- Is_Known_Branch --
3102 ---------------------
3104 function Is_Known_Branch return Boolean is
3106 if Etype (C) = Standard_Boolean
3107 and then Is_Entity_Name (C)
3109 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3111 Test_Result := Entity (C) = Standard_True;
3114 elsif Is_Boolean_Type (Etype (C))
3115 and then Nkind (C) = N_Unchecked_Type_Conversion
3116 and then Is_Entity_Name (Expression (C))
3117 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3120 Chars (Entity (Expression (C))) = Chars (Standard_True);
3126 end Is_Known_Branch;
3132 procedure Track (N : Node_Id; Loc : Node_Id) is
3133 Nod : constant Node_Id := Original_Node (N);
3136 if Nkind (Nod) in N_Op_Compare then
3137 Track (Left_Opnd (Nod), Loc);
3138 Track (Right_Opnd (Nod), Loc);
3140 elsif Is_Entity_Name (Nod)
3141 and then Is_Object (Entity (Nod))
3144 CV : constant Node_Id := Current_Value (Entity (Nod));
3147 if Present (CV) then
3148 Error_Msg_Sloc := Sloc (CV);
3150 if Nkind (CV) not in N_Subexpr then
3151 Error_Msg_N ("\\?(see test #)", Loc);
3153 elsif Nkind (Parent (CV)) =
3154 N_Case_Statement_Alternative
3156 Error_Msg_N ("\\?(see case alternative #)", Loc);
3159 Error_Msg_N ("\\?(see assignment #)", Loc);
3166 -- Start of processing for Warn_On_Known_Condition
3169 -- Adjust SCO condition if from source
3172 and then Comes_From_Source (Orig)
3173 and then Is_Known_Branch
3179 Atrue := Test_Result;
3181 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3185 Set_SCO_Condition (Orig, Atrue);
3189 -- Argument replacement in an inlined body can make conditions static.
3190 -- Do not emit warnings in this case.
3192 if In_Inlined_Body then
3196 if Constant_Condition_Warnings
3197 and then Is_Known_Branch
3198 and then Comes_From_Source (Orig)
3199 and then not In_Instance
3201 -- Don't warn if comparison of result of attribute against a constant
3202 -- value, since this is likely legitimate conditional compilation.
3204 if Nkind (Orig) in N_Op_Compare
3205 and then Compile_Time_Known_Value (Right_Opnd (Orig))
3206 and then Nkind (Original_Node (Left_Opnd (Orig))) =
3207 N_Attribute_Reference
3212 -- See if this is in a statement or a declaration
3216 -- If tree is not attached, do not issue warning (this is very
3217 -- peculiar, and probably arises from some other error condition)
3222 -- If we are in a declaration, then no warning, since in practice
3223 -- conditionals in declarations are used for intended tests which
3224 -- may be known at compile time, e.g. things like
3226 -- x : constant Integer := 2 + (Word'Size = 32);
3228 -- And a warning is annoying in such cases
3230 elsif Nkind (P) in N_Declaration
3232 Nkind (P) in N_Later_Decl_Item
3236 -- Don't warn in assert or check pragma, since presumably tests in
3237 -- such a context are very definitely intended, and might well be
3238 -- known at compile time. Note that we have to test the original
3239 -- node, since assert pragmas get rewritten at analysis time.
3241 elsif Nkind (Original_Node (P)) = N_Pragma
3242 and then Nam_In (Pragma_Name (Original_Node (P)), Name_Assert,
3248 exit when Is_Statement (P);
3252 -- Here we issue the warning unless some sub-operand has warnings
3253 -- set off, in which case we suppress the warning for the node. If
3254 -- the original expression is an inequality, it has been expanded
3255 -- into a negation, and the value of the original expression is the
3256 -- negation of the equality. If the expression is an entity that
3257 -- appears within a negation, it is clearer to flag the negation
3258 -- itself, and report on its constant value.
3260 if not Operand_Has_Warnings_Suppressed (C) then
3262 True_Branch : Boolean := Test_Result;
3263 Cond : Node_Id := C;
3266 if Present (Parent (C))
3267 and then Nkind (Parent (C)) = N_Op_Not
3269 True_Branch := not True_Branch;
3274 if Is_Entity_Name (Original_Node (C))
3275 and then Nkind (Cond) /= N_Op_Not
3278 ("object & is always True?c?", Cond, Original_Node (C));
3279 Track (Original_Node (C), Cond);
3282 Error_Msg_N ("condition is always True?c?", Cond);
3287 Error_Msg_N ("condition is always False?c?", Cond);
3293 end Warn_On_Known_Condition;
3295 ---------------------------------------
3296 -- Warn_On_Modified_As_Out_Parameter --
3297 ---------------------------------------
3299 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3302 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3303 or else Warn_On_All_Unread_Out_Parameters;
3304 end Warn_On_Modified_As_Out_Parameter;
3306 ---------------------------------
3307 -- Warn_On_Overlapping_Actuals --
3308 ---------------------------------
3310 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3311 Act1, Act2 : Node_Id;
3312 Form1, Form2 : Entity_Id;
3314 function Is_Covered_Formal (Formal : Node_Id) return Boolean;
3315 -- Return True if Formal is covered by the rule
3317 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean;
3318 -- Two names are known to refer to the same object if the two names
3319 -- are known to denote the same object; or one of the names is a
3320 -- selected_component, indexed_component, or slice and its prefix is
3321 -- known to refer to the same object as the other name; or one of the
3322 -- two names statically denotes a renaming declaration whose renamed
3323 -- object_name is known to refer to the same object as the other name
3324 -- (RM 6.4.1(6.11/3))
3326 -----------------------
3327 -- Refer_Same_Object --
3328 -----------------------
3330 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is
3332 return Denotes_Same_Object (Act1, Act2)
3333 or else Denotes_Same_Prefix (Act1, Act2);
3334 end Refer_Same_Object;
3336 -----------------------
3337 -- Is_Covered_Formal --
3338 -----------------------
3340 function Is_Covered_Formal (Formal : Node_Id) return Boolean is
3343 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter)
3344 and then (Is_Elementary_Type (Etype (Formal))
3345 or else Is_Record_Type (Etype (Formal))
3346 or else Is_Array_Type (Etype (Formal)));
3347 end Is_Covered_Formal;
3350 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then
3354 -- Exclude calls rewritten as enumeration literals
3356 if Nkind (N) not in N_Subprogram_Call
3357 and then Nkind (N) /= N_Entry_Call_Statement
3362 -- If a call C has two or more parameters of mode in out or out that are
3363 -- of an elementary type, then the call is legal only if for each name
3364 -- N that is passed as a parameter of mode in out or out to the call C,
3365 -- there is no other name among the other parameters of mode in out or
3366 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3368 -- If appropriate warning switch is set, we also report warnings on
3369 -- overlapping parameters that are record types or array types.
3371 Form1 := First_Formal (Subp);
3372 Act1 := First_Actual (N);
3373 while Present (Form1) and then Present (Act1) loop
3374 if Is_Covered_Formal (Form1) then
3375 Form2 := First_Formal (Subp);
3376 Act2 := First_Actual (N);
3377 while Present (Form2) and then Present (Act2) loop
3379 and then Is_Covered_Formal (Form2)
3380 and then Refer_Same_Object (Act1, Act2)
3382 -- Guard against previous errors
3385 or else No (Etype (Act1))
3386 or else No (Etype (Act2))
3390 -- If the actual is a function call in prefix notation,
3391 -- there is no real overlap.
3393 elsif Nkind (Act2) = N_Function_Call then
3396 -- If type is not by-copy, assume that aliasing is intended
3399 Present (Underlying_Type (Etype (Form1)))
3401 (Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3403 Convention (Underlying_Type (Etype (Form1))) =
3404 Convention_Ada_Pass_By_Reference)
3408 -- Under Ada 2012 we only report warnings on overlapping
3409 -- arrays and record types if switch is set.
3411 elsif Ada_Version >= Ada_2012
3412 and then not Is_Elementary_Type (Etype (Form1))
3413 and then not Warn_On_Overlap
3417 -- Here we may need to issue overlap message
3422 -- Overlap checking is an error only in Ada 2012. For
3423 -- earlier versions of Ada, this is a warning.
3425 Ada_Version < Ada_2012
3427 -- Overlap is only illegal in Ada 2012 in the case of
3428 -- elementary types (passed by copy). For other types,
3429 -- we always have a warning in all Ada versions.
3431 or else not Is_Elementary_Type (Etype (Form1))
3433 -- Finally, debug flag -gnatd.E changes the error to a
3434 -- warning even in Ada 2012 mode.
3436 or else Error_To_Warning;
3443 -- Find matching actual
3445 Act := First_Actual (N);
3446 Form := First_Formal (Subp);
3447 while Act /= Act2 loop
3452 if Is_Elementary_Type (Etype (Act1))
3453 and then Ekind (Form2) = E_In_Parameter
3455 null; -- No real aliasing
3457 elsif Is_Elementary_Type (Etype (Act2))
3458 and then Ekind (Form2) = E_In_Parameter
3462 -- If the call was written in prefix notation, and
3463 -- thus its prefix before rewriting was a selected
3464 -- component, count only visible actuals in the call.
3466 elsif Is_Entity_Name (First_Actual (N))
3467 and then Nkind (Original_Node (N)) = Nkind (N)
3468 and then Nkind (Name (Original_Node (N))) =
3469 N_Selected_Component
3471 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3473 Entity (Prefix (Name (Original_Node (N)))) =
3474 Entity (First_Actual (N))
3476 if Act1 = First_Actual (N) then
3478 ("<`IN OUT` prefix overlaps with "
3479 & "actual for&", Act1, Form);
3482 -- For greater clarity, give name of formal
3484 Error_Msg_Node_2 := Form;
3486 ("<writable actual for & overlaps with "
3487 & "actual for&", Act1, Form);
3491 -- For greater clarity, give name of formal
3493 Error_Msg_Node_2 := Form;
3495 -- This is one of the messages
3498 ("<writable actual for & overlaps with "
3499 & "actual for&", Act1, Form1);
3507 Next_Formal (Form2);
3512 Next_Formal (Form1);
3515 end Warn_On_Overlapping_Actuals;
3517 ------------------------------
3518 -- Warn_On_Suspicious_Index --
3519 ------------------------------
3521 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3524 -- Set to lower bound for a suspicious type
3527 -- Entity for array reference
3532 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3533 -- Tests to see if Typ is a type for which we may have a suspicious
3534 -- index, namely an unconstrained array type, whose lower bound is
3535 -- either zero or one. If so, True is returned, and Low_Bound is set
3536 -- to this lower bound. If not, False is returned, and Low_Bound is
3537 -- undefined on return.
3539 -- For now, we limit this to standard string types, so any other
3540 -- unconstrained types return False. We may change our minds on this
3541 -- later on, but strings seem the most important case.
3543 procedure Test_Suspicious_Index;
3544 -- Test if index is of suspicious type and if so, generate warning
3546 ------------------------
3547 -- Is_Suspicious_Type --
3548 ------------------------
3550 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3554 if Is_Array_Type (Typ)
3555 and then not Is_Constrained (Typ)
3556 and then Number_Dimensions (Typ) = 1
3557 and then (Root_Type (Typ) = Standard_String
3559 Root_Type (Typ) = Standard_Wide_String
3561 Root_Type (Typ) = Standard_Wide_Wide_String)
3562 and then not Has_Warnings_Off (Typ)
3564 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3566 if Compile_Time_Known_Value (LB) then
3567 Low_Bound := Expr_Value (LB);
3568 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3573 end Is_Suspicious_Type;
3575 ---------------------------
3576 -- Test_Suspicious_Index --
3577 ---------------------------
3579 procedure Test_Suspicious_Index is
3581 function Length_Reference (N : Node_Id) return Boolean;
3582 -- Check if node N is of the form Name'Length
3585 -- Generate first warning line
3587 ----------------------
3588 -- Length_Reference --
3589 ----------------------
3591 function Length_Reference (N : Node_Id) return Boolean is
3592 R : constant Node_Id := Original_Node (N);
3595 Nkind (R) = N_Attribute_Reference
3596 and then Attribute_Name (R) = Name_Length
3597 and then Is_Entity_Name (Prefix (R))
3598 and then Entity (Prefix (R)) = Ent;
3599 end Length_Reference;
3607 Error_Msg_Uint_1 := Low_Bound;
3608 Error_Msg_FE -- CODEFIX
3609 ("?w?index for& may assume lower bound of^", X, Ent);
3612 -- Start of processing for Test_Suspicious_Index
3615 -- Nothing to do if subscript does not come from source (we don't
3616 -- want to give garbage warnings on compiler expanded code, e.g. the
3617 -- loops generated for slice assignments. Such junk warnings would
3618 -- be placed on source constructs with no subscript in sight!)
3620 if not Comes_From_Source (Original_Node (X)) then
3624 -- Case where subscript is a constant integer
3626 if Nkind (X) = N_Integer_Literal then
3629 -- Case where original form of subscript is an integer literal
3631 if Nkind (Original_Node (X)) = N_Integer_Literal then
3632 if Intval (X) = Low_Bound then
3633 Error_Msg_FE -- CODEFIX
3634 ("\?w?suggested replacement: `&''First`", X, Ent);
3636 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3637 Error_Msg_FE -- CODEFIX
3638 ("\?w?suggested replacement: `&''First + ^`", X, Ent);
3642 -- Case where original form of subscript is more complex
3645 -- Build string X'First - 1 + expression where the expression
3646 -- is the original subscript. If the expression starts with "1
3647 -- + ", then the "- 1 + 1" is elided.
3649 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3650 Error_Msg_Strlen := 13;
3653 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3654 Tref : constant Source_Buffer_Ptr :=
3655 Source_Text (Get_Source_File_Index (Sref));
3656 -- Tref (Sref) is used to scan the subscript
3659 -- Parentheses counter when scanning subscript
3662 -- Tref (Sref) points to start of subscript
3664 -- Elide - 1 if subscript starts with 1 +
3666 if Tref (Sref .. Sref + 2) = "1 +" then
3667 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3670 elsif Tref (Sref .. Sref + 1) = "1+" then
3671 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3675 -- Now we will copy the subscript to the string buffer
3679 -- Count parens, exit if terminating right paren. Note
3680 -- check to ignore paren appearing as character literal.
3682 if Tref (Sref + 1) = '''
3684 Tref (Sref - 1) = '''
3688 if Tref (Sref) = '(' then
3690 elsif Tref (Sref) = ')' then
3696 -- Done if terminating double dot (slice case)
3699 and then (Tref (Sref .. Sref + 1) = ".."
3701 Tref (Sref .. Sref + 2) = " ..");
3703 -- Quit if we have hit EOF character, something wrong
3705 if Tref (Sref) = EOF then
3709 -- String literals are too much of a pain to handle
3711 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3715 -- If we have a 'Range reference, then this is a case
3716 -- where we cannot easily give a replacement. Don't try!
3718 if Tref (Sref .. Sref + 4) = "range"
3719 and then Tref (Sref - 1) < 'A'
3720 and then Tref (Sref + 5) < 'A'
3725 -- Else store next character
3727 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3728 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3731 -- If we get more than 40 characters then the expression
3732 -- is too long to copy, or something has gone wrong. In
3733 -- either case, just skip the attempt at a suggested fix.
3735 if Error_Msg_Strlen > 40 then
3741 -- Replacement subscript is now in string buffer
3743 Error_Msg_FE -- CODEFIX
3744 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent);
3747 -- Case where subscript is of the form X'Length
3749 elsif Length_Reference (X) then
3751 Error_Msg_Node_2 := Ent;
3753 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3756 -- Case where subscript is of the form X'Length - expression
3758 elsif Nkind (X) = N_Op_Subtract
3759 and then Length_Reference (Left_Opnd (X))
3762 Error_Msg_Node_2 := Ent;
3764 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3765 Left_Opnd (X), Ent);
3767 end Test_Suspicious_Index;
3769 -- Start of processing for Warn_On_Suspicious_Index
3772 -- Only process if warnings activated
3774 if Warn_On_Assumed_Low_Bound then
3776 -- Test if array is simple entity name
3778 if Is_Entity_Name (Name) then
3780 -- Test if array is parameter of unconstrained string type
3782 Ent := Entity (Name);
3786 and then Is_Suspicious_Type (Typ)
3787 and then not Low_Bound_Tested (Ent)
3789 Test_Suspicious_Index;
3793 end Warn_On_Suspicious_Index;
3795 --------------------------------------
3796 -- Warn_On_Unassigned_Out_Parameter --
3797 --------------------------------------
3799 procedure Warn_On_Unassigned_Out_Parameter
3800 (Return_Node : Node_Id;
3801 Scope_Id : Entity_Id)
3807 -- Ignore if procedure or return statement does not come from source
3809 if not Comes_From_Source (Scope_Id)
3810 or else not Comes_From_Source (Return_Node)
3815 -- Loop through formals
3817 Form := First_Formal (Scope_Id);
3818 while Present (Form) loop
3820 -- We are only interested in OUT parameters that come from source
3821 -- and are never set in the source, and furthermore only in scalars
3822 -- since non-scalars generate too many false positives.
3824 if Ekind (Form) = E_Out_Parameter
3825 and then Never_Set_In_Source_Check_Spec (Form)
3826 and then Is_Scalar_Type (Etype (Form))
3827 and then not Present (Unset_Reference (Form))
3829 -- Before we issue the warning, an add ad hoc defence against the
3830 -- most common case of false positives with this warning which is
3831 -- the case where there is a Boolean OUT parameter that has been
3832 -- set, and whose meaning is "ignore the values of the other
3833 -- parameters". We can't of course reliably tell this case at
3834 -- compile time, but the following test kills a lot of false
3835 -- positives, without generating a significant number of false
3836 -- negatives (missed real warnings).
3838 Form2 := First_Formal (Scope_Id);
3839 while Present (Form2) loop
3840 if Ekind (Form2) = E_Out_Parameter
3841 and then Root_Type (Etype (Form2)) = Standard_Boolean
3842 and then not Never_Set_In_Source_Check_Spec (Form2)
3847 Next_Formal (Form2);
3850 -- Here all conditions are met, record possible unset reference
3852 Set_Unset_Reference (Form, Return_Node);
3857 end Warn_On_Unassigned_Out_Parameter;
3859 ---------------------------------
3860 -- Warn_On_Unreferenced_Entity --
3861 ---------------------------------
3863 procedure Warn_On_Unreferenced_Entity
3864 (Spec_E : Entity_Id;
3865 Body_E : Entity_Id := Empty)
3867 E : Entity_Id := Spec_E;
3870 if not Referenced_Check_Spec (E)
3871 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3872 and then not Warnings_Off_Check_Spec (E)
3877 -- Case of variable that is assigned but not read. We suppress
3878 -- the message if the variable is volatile, has an address
3879 -- clause, is aliased, or is a renaming, or is imported.
3881 if Referenced_As_LHS_Check_Spec (E)
3882 and then No (Address_Clause (E))
3883 and then not Is_Volatile (E)
3885 if Warn_On_Modified_Unread
3886 and then not Is_Imported (E)
3887 and then not Is_Aliased (E)
3888 and then No (Renamed_Object (E))
3890 if not Has_Pragma_Unmodified_Check_Spec (E) then
3891 Error_Msg_N -- CODEFIX
3892 ("?u?variable & is assigned but never read!", E);
3895 Set_Last_Assignment (E, Empty);
3898 -- Normal case of neither assigned nor read (exclude variables
3899 -- referenced as out parameters, since we already generated
3900 -- appropriate warnings at the call point in this case).
3902 elsif not Referenced_As_Out_Parameter (E) then
3904 -- We suppress the message for types for which a valid
3905 -- pragma Unreferenced_Objects has been given, otherwise
3906 -- we go ahead and give the message.
3908 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3910 -- Distinguish renamed case in message
3912 if Present (Renamed_Object (E))
3913 and then Comes_From_Source (Renamed_Object (E))
3915 Error_Msg_N -- CODEFIX
3916 ("?u?renamed variable & is not referenced!", E);
3918 Error_Msg_N -- CODEFIX
3919 ("?u?variable & is not referenced!", E);
3925 if Present (Renamed_Object (E))
3926 and then Comes_From_Source (Renamed_Object (E))
3928 Error_Msg_N -- CODEFIX
3929 ("?u?renamed constant & is not referenced!", E);
3931 Error_Msg_N -- CODEFIX
3932 ("?u?constant & is not referenced!", E);
3935 when E_In_Parameter |
3936 E_In_Out_Parameter =>
3938 -- Do not emit message for formals of a renaming, because
3939 -- they are never referenced explicitly.
3941 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /=
3942 N_Subprogram_Renaming_Declaration
3944 -- Suppress this message for an IN OUT parameter of a
3945 -- non-scalar type, since it is normal to have only an
3946 -- assignment in such a case.
3948 if Ekind (E) = E_In_Parameter
3949 or else not Referenced_As_LHS_Check_Spec (E)
3950 or else Is_Scalar_Type (Etype (E))
3952 if Present (Body_E) then
3956 if not Is_Trivial_Subprogram (Scope (E)) then
3957 Error_Msg_NE -- CODEFIX
3958 ("?u?formal parameter & is not referenced!",
3964 when E_Out_Parameter =>
3967 when E_Discriminant =>
3968 Error_Msg_N ("?u?discriminant & is not referenced!", E);
3970 when E_Named_Integer |
3972 Error_Msg_N -- CODEFIX
3973 ("?u?named number & is not referenced!", E);
3975 when Formal_Object_Kind =>
3976 Error_Msg_N -- CODEFIX
3977 ("?u?formal object & is not referenced!", E);
3979 when E_Enumeration_Literal =>
3980 Error_Msg_N -- CODEFIX
3981 ("?u?literal & is not referenced!", E);
3984 Error_Msg_N -- CODEFIX
3985 ("?u?function & is not referenced!", E);
3988 Error_Msg_N -- CODEFIX
3989 ("?u?procedure & is not referenced!", E);
3992 Error_Msg_N -- CODEFIX
3993 ("?u?package & is not referenced!", E);
3996 Error_Msg_N -- CODEFIX
3997 ("?u?exception & is not referenced!", E);
4000 Error_Msg_N -- CODEFIX
4001 ("?u?label & is not referenced!", E);
4003 when E_Generic_Procedure =>
4004 Error_Msg_N -- CODEFIX
4005 ("?u?generic procedure & is never instantiated!", E);
4007 when E_Generic_Function =>
4008 Error_Msg_N -- CODEFIX
4009 ("?u?generic function & is never instantiated!", E);
4012 Error_Msg_N -- CODEFIX
4013 ("?u?type & is not referenced!", E);
4016 Error_Msg_N -- CODEFIX
4017 ("?u?& is not referenced!", E);
4020 -- Kill warnings on the entity on which the message has been posted
4022 Set_Warnings_Off (E);
4024 end Warn_On_Unreferenced_Entity;
4026 --------------------------------
4027 -- Warn_On_Useless_Assignment --
4028 --------------------------------
4030 procedure Warn_On_Useless_Assignment
4032 N : Node_Id := Empty)
4037 function Check_Ref (N : Node_Id) return Traverse_Result;
4038 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4039 -- the entity in question is found.
4041 function Test_No_Refs is new Traverse_Func (Check_Ref);
4047 function Check_Ref (N : Node_Id) return Traverse_Result is
4049 -- Check reference to our identifier. We use name equality here
4050 -- because the exception handlers have not yet been analyzed. This
4051 -- is not quite right, but it really does not matter that we fail
4052 -- to output the warning in some obscure cases of name clashes.
4054 if Nkind (N) = N_Identifier
4055 and then Chars (N) = Chars (Ent)
4063 -- Start of processing for Warn_On_Useless_Assignment
4066 -- Check if this is a case we want to warn on, a scalar or access
4067 -- variable with the last assignment field set, with warnings enabled,
4068 -- and which is not imported or exported. We also check that it is OK
4069 -- to capture the value. We are not going to capture any value, but
4070 -- the warning message depends on the same kind of conditions.
4072 if Is_Assignable (Ent)
4073 and then not Is_Return_Object (Ent)
4074 and then Present (Last_Assignment (Ent))
4075 and then not Is_Imported (Ent)
4076 and then not Is_Exported (Ent)
4077 and then Safe_To_Capture_Value (N, Ent)
4078 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
4080 -- Before we issue the message, check covering exception handlers.
4081 -- Search up tree for enclosing statement sequences and handlers.
4083 P := Parent (Last_Assignment (Ent));
4084 while Present (P) loop
4086 -- Something is really wrong if we don't find a handled statement
4087 -- sequence, so just suppress the warning.
4090 Set_Last_Assignment (Ent, Empty);
4093 -- When we hit a package/subprogram body, issue warning and exit
4095 elsif Nkind (P) = N_Subprogram_Body
4096 or else Nkind (P) = N_Package_Body
4098 -- Case of assigned value never referenced
4102 LA : constant Node_Id := Last_Assignment (Ent);
4105 -- Don't give this for OUT and IN OUT formals, since
4106 -- clearly caller may reference the assigned value. Also
4107 -- never give such warnings for internal variables.
4109 if Ekind (Ent) = E_Variable
4110 and then not Is_Internal_Name (Chars (Ent))
4112 -- Give appropriate message, distinguishing between
4113 -- assignment statements and out parameters.
4115 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4116 N_Parameter_Association)
4119 ("?m?& modified by call, but value never "
4120 & "referenced", LA, Ent);
4123 Error_Msg_NE -- CODEFIX
4124 ("?m?useless assignment to&, value never "
4125 & "referenced!", LA, Ent);
4130 -- Case of assigned value overwritten
4134 LA : constant Node_Id := Last_Assignment (Ent);
4137 Error_Msg_Sloc := Sloc (N);
4139 -- Give appropriate message, distinguishing between
4140 -- assignment statements and out parameters.
4142 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4143 N_Parameter_Association)
4146 ("?m?& modified by call, but value overwritten #!",
4149 Error_Msg_NE -- CODEFIX
4150 ("?m?useless assignment to&, value overwritten #!",
4156 -- Clear last assignment indication and we are done
4158 Set_Last_Assignment (Ent, Empty);
4161 -- Enclosing handled sequence of statements
4163 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4165 -- Check exception handlers present
4167 if Present (Exception_Handlers (P)) then
4169 -- If we are not at the top level, we regard an inner
4170 -- exception handler as a decisive indicator that we should
4171 -- not generate the warning, since the variable in question
4172 -- may be accessed after an exception in the outer block.
4174 if Nkind (Parent (P)) /= N_Subprogram_Body
4175 and then Nkind (Parent (P)) /= N_Package_Body
4177 Set_Last_Assignment (Ent, Empty);
4180 -- Otherwise we are at the outer level. An exception
4181 -- handler is significant only if it references the
4182 -- variable in question, or if the entity in question
4183 -- is an OUT or IN OUT parameter, which which case
4184 -- the caller can reference it after the exception
4185 -- handler completes.
4188 if Is_Formal (Ent) then
4189 Set_Last_Assignment (Ent, Empty);
4193 X := First (Exception_Handlers (P));
4194 while Present (X) loop
4195 if Test_No_Refs (X) = Abandon then
4196 Set_Last_Assignment (Ent, Empty);
4210 end Warn_On_Useless_Assignment;
4212 ---------------------------------
4213 -- Warn_On_Useless_Assignments --
4214 ---------------------------------
4216 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4219 if Warn_On_Modified_Unread
4220 and then In_Extended_Main_Source_Unit (E)
4222 Ent := First_Entity (E);
4223 while Present (Ent) loop
4224 Warn_On_Useless_Assignment (Ent);
4228 end Warn_On_Useless_Assignments;
4230 -----------------------------
4231 -- Warnings_Off_Check_Spec --
4232 -----------------------------
4234 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4236 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4238 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4239 -- to mess with flags on both entities.
4241 return Has_Warnings_Off (E)
4243 Has_Warnings_Off (Spec_Entity (E));
4246 return Has_Warnings_Off (E);
4248 end Warnings_Off_Check_Spec;