1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2012, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Debug; use Debug;
28 with Einfo; use Einfo;
29 with Errout; use Errout;
30 with Exp_Code; use Exp_Code;
31 with Fname; use Fname;
33 with Namet; use Namet;
34 with Nlists; use Nlists;
36 with Par_SCO; use Par_SCO;
37 with Rtsfind; use Rtsfind;
39 with Sem_Ch8; use Sem_Ch8;
40 with Sem_Aux; use Sem_Aux;
41 with Sem_Eval; use Sem_Eval;
42 with Sem_Util; use Sem_Util;
43 with Sinfo; use Sinfo;
44 with Sinput; use Sinput;
45 with Snames; use Snames;
46 with Stand; use Stand;
47 with Stringt; use Stringt;
48 with Uintp; use Uintp;
50 package body Sem_Warn is
52 -- The following table collects Id's of entities that are potentially
53 -- unreferenced. See Check_Unset_Reference for further details.
54 -- ??? Check_Unset_Reference has zero information about this table.
56 package Unreferenced_Entities is new Table.Table (
57 Table_Component_Type => Entity_Id,
58 Table_Index_Type => Nat,
60 Table_Initial => Alloc.Unreferenced_Entities_Initial,
61 Table_Increment => Alloc.Unreferenced_Entities_Increment,
62 Table_Name => "Unreferenced_Entities");
64 -- The following table collects potential warnings for IN OUT parameters
65 -- that are referenced but not modified. These warnings are processed when
66 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
67 -- The reason that we defer output of these messages is that we want to
68 -- detect the case where the relevant procedure is used as a generic actual
69 -- in an instantiation, since we suppress the warnings in this case. The
70 -- flag Used_As_Generic_Actual will be set in this case, but only at the
71 -- point of usage. Similarly, we suppress the message if the address of the
72 -- procedure is taken, where the flag Address_Taken may be set later.
74 package In_Out_Warnings is new Table.Table (
75 Table_Component_Type => Entity_Id,
76 Table_Index_Type => Nat,
78 Table_Initial => Alloc.In_Out_Warnings_Initial,
79 Table_Increment => Alloc.In_Out_Warnings_Increment,
80 Table_Name => "In_Out_Warnings");
82 --------------------------------------------------------
83 -- Handling of Warnings Off, Unmodified, Unreferenced --
84 --------------------------------------------------------
86 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
87 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
88 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
90 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
91 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
92 -- must follow some important rules.
94 -- Call these functions as late as possible, after completing all other
95 -- tests, just before the warnings is given. For example, don't write:
97 -- if not Has_Warnings_Off (E)
98 -- and then some-other-predicate-on-E then ..
100 -- Instead the following is preferred
102 -- if some-other-predicate-on-E
103 -- and then Has_Warnings_Off (E)
105 -- This way if some-other-predicate is false, we avoid a false indication
106 -- that a Warnings (Off, E) pragma was useful in preventing a warning.
108 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
109 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
110 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
111 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
112 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
113 -- and so a subsequent test is not needed anyway (though it is harmless).
115 -----------------------
116 -- Local Subprograms --
117 -----------------------
119 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean;
120 -- This returns true if the entity E is declared within a generic package.
121 -- The point of this is to detect variables which are not assigned within
122 -- the generic, but might be assigned outside the package for any given
123 -- instance. These are cases where we leave the warnings to be posted for
124 -- the instance, when we will know more.
126 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id;
127 -- If E is a parameter entity for a subprogram body, then this function
128 -- returns the corresponding spec entity, if not, E is returned unchanged.
130 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean;
131 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
132 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
133 -- a body formal, the setting of the flag in the corresponding spec is
134 -- also checked (and True returned if either flag is True).
136 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean;
137 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
138 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
139 -- a body formal, the setting of the flag in the corresponding spec is
140 -- also checked (and True returned if either flag is True).
142 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean;
143 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
144 -- this is simply the setting of the flag Never_Set_In_Source. If E is
145 -- a body formal, the setting of the flag in the corresponding spec is
146 -- also checked (and False returned if either flag is False).
148 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
149 -- This function traverses the expression tree represented by the node N
150 -- and determines if any sub-operand is a reference to an entity for which
151 -- the Warnings_Off flag is set. True is returned if such an entity is
152 -- encountered, and False otherwise.
154 function Referenced_Check_Spec (E : Entity_Id) return Boolean;
155 -- Tests Referenced status for entity E. If E is not a formal, this is
156 -- simply the setting of the flag Referenced. If E is a body formal, the
157 -- setting of the flag in the corresponding spec is also checked (and True
158 -- returned if either flag is True).
160 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean;
161 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
162 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
163 -- formal, the setting of the flag in the corresponding spec is also
164 -- checked (and True returned if either flag is True).
166 function Referenced_As_Out_Parameter_Check_Spec
167 (E : Entity_Id) return Boolean;
168 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
169 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
170 -- is a body formal, the setting of the flag in the corresponding spec is
171 -- also checked (and True returned if either flag is True).
173 procedure Warn_On_Unreferenced_Entity
175 Body_E : Entity_Id := Empty);
176 -- Output warnings for unreferenced entity E. For the case of an entry
177 -- formal, Body_E is the corresponding body entity for a particular
178 -- accept statement, and the message is posted on Body_E. In all other
179 -- cases, Body_E is ignored and must be Empty.
181 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean;
182 -- Returns True if Warnings_Off is set for the entity E or (in the case
183 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
185 --------------------------
186 -- Check_Code_Statement --
187 --------------------------
189 procedure Check_Code_Statement (N : Node_Id) is
191 -- If volatile, nothing to worry about
193 if Is_Asm_Volatile (N) then
197 -- Warn if no input or no output
199 Setup_Asm_Inputs (N);
201 if No (Asm_Input_Value) then
203 ("?code statement with no inputs should usually be Volatile!", N);
207 Setup_Asm_Outputs (N);
209 if No (Asm_Output_Variable) then
211 ("?code statement with no outputs should usually be Volatile!", N);
214 end Check_Code_Statement;
216 ---------------------------------
217 -- Check_Infinite_Loop_Warning --
218 ---------------------------------
220 -- The case we look for is a while loop which tests a local variable, where
221 -- there is no obvious direct or possible indirect update of the variable
222 -- within the body of the loop.
224 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
225 Expression : Node_Id := Empty;
226 -- Set to WHILE or EXIT WHEN condition to be tested
228 Ref : Node_Id := Empty;
229 -- Reference in Expression to variable that might not be modified
230 -- in loop, indicating a possible infinite loop.
232 Var : Entity_Id := Empty;
233 -- Corresponding entity (entity of Ref)
235 Function_Call_Found : Boolean := False;
236 -- True if Find_Var found a function call in the condition
238 procedure Find_Var (N : Node_Id);
239 -- Inspect condition to see if it depends on a single entity reference.
240 -- If so, Ref is set to point to the reference node, and Var is set to
241 -- the referenced Entity.
243 function Has_Indirection (T : Entity_Id) return Boolean;
244 -- If the controlling variable is an access type, or is a record type
245 -- with access components, assume that it is changed indirectly and
246 -- suppress the warning. As a concession to low-level programming, in
247 -- particular within Declib, we also suppress warnings on a record
248 -- type that contains components of type Address or Short_Address.
250 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
251 -- Given an entity name, see if the name appears to have something to
252 -- do with I/O or network stuff, and if so, return True. Used to kill
253 -- some false positives on a heuristic basis that such functions will
254 -- likely have some strange side effect dependencies. A rather funny
255 -- kludge, but warning messages are in the heuristics business.
257 function Test_Ref (N : Node_Id) return Traverse_Result;
258 -- Test for reference to variable in question. Returns Abandon if
259 -- matching reference found. Used in instantiation of No_Ref_Found.
261 function No_Ref_Found is new Traverse_Func (Test_Ref);
262 -- Function to traverse body of procedure. Returns Abandon if matching
269 procedure Find_Var (N : Node_Id) is
271 -- Condition is a direct variable reference
273 if Is_Entity_Name (N) then
277 -- Case of condition is a comparison with compile time known value
279 elsif Nkind (N) in N_Op_Compare then
280 if Compile_Time_Known_Value (Right_Opnd (N)) then
281 Find_Var (Left_Opnd (N));
283 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
284 Find_Var (Right_Opnd (N));
286 -- Ignore any other comparison
292 -- If condition is a negation, check its operand
294 elsif Nkind (N) = N_Op_Not then
295 Find_Var (Right_Opnd (N));
297 -- Case of condition is function call
299 elsif Nkind (N) = N_Function_Call then
301 Function_Call_Found := True;
303 -- Forget it if function name is not entity, who knows what
304 -- we might be calling?
306 if not Is_Entity_Name (Name (N)) then
309 -- Forget it if function name is suspicious. A strange test
310 -- but warning generation is in the heuristics business!
312 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
315 -- Forget it if warnings are suppressed on function entity
317 elsif Has_Warnings_Off (Entity (Name (N))) then
321 -- OK, see if we have one argument
324 PA : constant List_Id := Parameter_Associations (N);
327 -- One argument, so check the argument
330 and then List_Length (PA) = 1
332 if Nkind (First (PA)) = N_Parameter_Association then
333 Find_Var (Explicit_Actual_Parameter (First (PA)));
335 Find_Var (First (PA));
345 -- Any other kind of node is not something we warn for
352 ---------------------
353 -- Has_Indirection --
354 ---------------------
356 function Has_Indirection (T : Entity_Id) return Boolean is
361 if Is_Access_Type (T) then
364 elsif Is_Private_Type (T)
365 and then Present (Full_View (T))
366 and then Is_Access_Type (Full_View (T))
370 elsif Is_Record_Type (T) then
373 elsif Is_Private_Type (T)
374 and then Present (Full_View (T))
375 and then Is_Record_Type (Full_View (T))
377 Rec := Full_View (T);
382 Comp := First_Component (Rec);
383 while Present (Comp) loop
384 if Is_Access_Type (Etype (Comp))
385 or else Is_Descendent_Of_Address (Etype (Comp))
390 Next_Component (Comp);
396 ---------------------------------
397 -- Is_Suspicious_Function_Name --
398 ---------------------------------
400 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
403 function Substring_Present (S : String) return Boolean;
404 -- Returns True if name buffer has given string delimited by non-
405 -- alphabetic characters or by end of string. S is lower case.
407 -----------------------
408 -- Substring_Present --
409 -----------------------
411 function Substring_Present (S : String) return Boolean is
412 Len : constant Natural := S'Length;
415 for J in 1 .. Name_Len - (Len - 1) loop
416 if Name_Buffer (J .. J + (Len - 1)) = S
419 or else Name_Buffer (J - 1) not in 'a' .. 'z')
422 or else Name_Buffer (J + Len) not in 'a' .. 'z')
429 end Substring_Present;
431 -- Start of processing for Is_Suspicious_Function_Name
435 while Present (S) and then S /= Standard_Standard loop
436 Get_Name_String (Chars (S));
438 if Substring_Present ("io")
439 or else Substring_Present ("file")
440 or else Substring_Present ("network")
449 end Is_Suspicious_Function_Name;
455 function Test_Ref (N : Node_Id) return Traverse_Result is
457 -- Waste of time to look at the expression we are testing
459 if N = Expression then
462 -- Direct reference to variable in question
464 elsif Is_Entity_Name (N)
465 and then Present (Entity (N))
466 and then Entity (N) = Var
468 -- If this is an lvalue, then definitely abandon, since
469 -- this could be a direct modification of the variable.
471 if May_Be_Lvalue (N) then
475 -- If we appear in the context of a procedure call, then also
476 -- abandon, since there may be issues of non-visible side
477 -- effects going on in the call.
486 exit when P = Loop_Statement;
488 -- Abandon if at procedure call, or something strange is
489 -- going on (perhaps a node with no parent that should
490 -- have one but does not?) As always, for a warning we
491 -- prefer to just abandon the warning than get into the
492 -- business of complaining about the tree structure here!
494 if No (P) or else Nkind (P) = N_Procedure_Call_Statement then
500 -- Reference to variable renaming variable in question
502 elsif Is_Entity_Name (N)
503 and then Present (Entity (N))
504 and then Ekind (Entity (N)) = E_Variable
505 and then Present (Renamed_Object (Entity (N)))
506 and then Is_Entity_Name (Renamed_Object (Entity (N)))
507 and then Entity (Renamed_Object (Entity (N))) = Var
508 and then May_Be_Lvalue (N)
512 -- Call to subprogram
514 elsif Nkind (N) in N_Subprogram_Call then
516 -- If subprogram is within the scope of the entity we are dealing
517 -- with as the loop variable, then it could modify this parameter,
518 -- so we abandon in this case. In the case of a subprogram that is
519 -- not an entity we also abandon. The check for no entity being
520 -- present is a defense against previous errors.
522 if not Is_Entity_Name (Name (N))
523 or else No (Entity (Name (N)))
524 or else Scope_Within (Entity (Name (N)), Scope (Var))
529 -- If any of the arguments are of type access to subprogram, then
530 -- we may have funny side effects, so no warning in this case.
535 Actual := First_Actual (N);
536 while Present (Actual) loop
537 if Is_Access_Subprogram_Type (Etype (Actual)) then
540 Next_Actual (Actual);
545 -- Declaration of the variable in question
547 elsif Nkind (N) = N_Object_Declaration
548 and then Defining_Identifier (N) = Var
553 -- All OK, continue scan
558 -- Start of processing for Check_Infinite_Loop_Warning
561 -- Skip processing if debug flag gnatd.w is set
563 if Debug_Flag_Dot_W then
567 -- Deal with Iteration scheme present
570 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
573 if Present (Iter) then
577 if Present (Condition (Iter)) then
579 -- Skip processing for while iteration with conditions actions,
580 -- since they make it too complicated to get the warning right.
582 if Present (Condition_Actions (Iter)) then
586 -- Capture WHILE condition
588 Expression := Condition (Iter);
590 -- For iteration, do not process, since loop will always terminate
592 elsif Present (Loop_Parameter_Specification (Iter)) then
598 -- Check chain of EXIT statements, we only process loops that have a
599 -- single exit condition (either a single EXIT WHEN statement, or a
600 -- WHILE loop not containing any EXIT WHEN statements).
603 Ident : constant Node_Id := Identifier (Loop_Statement);
607 -- If we don't have a proper chain set, ignore call entirely. This
608 -- happens because of previous errors.
610 if No (Entity (Ident))
611 or else Ekind (Entity (Ident)) /= E_Loop
616 -- Otherwise prepare to scan list of EXIT statements
618 Exit_Stmt := First_Exit_Statement (Entity (Ident));
619 while Present (Exit_Stmt) loop
621 -- Check for EXIT WHEN
623 if Present (Condition (Exit_Stmt)) then
625 -- Quit processing if EXIT WHEN in WHILE loop, or more than
626 -- one EXIT WHEN statement present in the loop.
628 if Present (Expression) then
631 -- Otherwise capture condition from EXIT WHEN statement
634 Expression := Condition (Exit_Stmt);
638 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
642 -- Return if no condition to test
644 if No (Expression) then
648 -- Initial conditions met, see if condition is of right form
650 Find_Var (Expression);
652 -- Nothing to do if local variable from source not found. If it's a
653 -- renaming, it is probably renaming something too complicated to deal
657 or else Ekind (Var) /= E_Variable
658 or else Is_Library_Level_Entity (Var)
659 or else not Comes_From_Source (Var)
660 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
664 -- Nothing to do if there is some indirection involved (assume that the
665 -- designated variable might be modified in some way we don't see).
666 -- However, if no function call was found, then we don't care about
667 -- indirections, because the condition must be something like "while X
668 -- /= null loop", so we don't care if X.all is modified in the loop.
670 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
673 -- Same sort of thing for volatile variable, might be modified by
674 -- some other task or by the operating system in some way.
676 elsif Is_Volatile (Var) then
680 -- Filter out case of original statement sequence starting with delay.
681 -- We assume this is a multi-tasking program and that the condition
682 -- is affected by other threads (some kind of busy wait).
685 Fstm : constant Node_Id :=
686 Original_Node (First (Statements (Loop_Statement)));
688 if Nkind (Fstm) = N_Delay_Relative_Statement
689 or else Nkind (Fstm) = N_Delay_Until_Statement
695 -- We have a variable reference of the right form, now we scan the loop
696 -- body to see if it looks like it might not be modified
698 if No_Ref_Found (Loop_Statement) = OK then
700 ("?variable& is not modified in loop body!", Ref, Var);
702 ("\?possible infinite loop!", Ref);
704 end Check_Infinite_Loop_Warning;
706 ----------------------------
707 -- Check_Low_Bound_Tested --
708 ----------------------------
710 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
712 if Comes_From_Source (Expr) then
714 L : constant Node_Id := Left_Opnd (Expr);
715 R : constant Node_Id := Right_Opnd (Expr);
717 if Nkind (L) = N_Attribute_Reference
718 and then Attribute_Name (L) = Name_First
719 and then Is_Entity_Name (Prefix (L))
720 and then Is_Formal (Entity (Prefix (L)))
722 Set_Low_Bound_Tested (Entity (Prefix (L)));
725 if Nkind (R) = N_Attribute_Reference
726 and then Attribute_Name (R) = Name_First
727 and then Is_Entity_Name (Prefix (R))
728 and then Is_Formal (Entity (Prefix (R)))
730 Set_Low_Bound_Tested (Entity (Prefix (R)));
734 end Check_Low_Bound_Tested;
736 ----------------------
737 -- Check_References --
738 ----------------------
740 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
747 Accept_Statement : Node_Id) return Entity_Id;
748 -- For an entry formal entity from an entry declaration, find the
749 -- corresponding body formal from the given accept statement.
751 function Missing_Subunits return Boolean;
752 -- We suppress warnings when there are missing subunits, because this
753 -- may generate too many false positives: entities in a parent may only
754 -- be referenced in one of the subunits. We make an exception for
755 -- subunits that contain no other stubs.
757 procedure Output_Reference_Error (M : String);
758 -- Used to output an error message. Deals with posting the error on the
759 -- body formal in the accept case.
761 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
762 -- This is true if the entity in question is potentially referenceable
763 -- from another unit. This is true for entities in packages that are at
764 -- the library level.
766 function Warnings_Off_E1 return Boolean;
767 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
768 -- or for the base type of E1T.
776 Accept_Statement : Node_Id) return Entity_Id
778 Body_Param : Node_Id;
782 -- Loop to find matching parameter in accept statement
784 Body_Param := First (Parameter_Specifications (Accept_Statement));
785 while Present (Body_Param) loop
786 Body_E := Defining_Identifier (Body_Param);
788 if Chars (Body_E) = Chars (E) then
795 -- Should never fall through, should always find a match
800 ----------------------
801 -- Missing_Subunits --
802 ----------------------
804 function Missing_Subunits return Boolean is
808 if not Unloaded_Subunits then
810 -- Normal compilation, all subunits are present
814 elsif E /= Main_Unit_Entity then
816 -- No warnings on a stub that is not the main unit
820 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
821 D := First (Declarations (Unit_Declaration_Node (E)));
822 while Present (D) loop
824 -- No warnings if the proper body contains nested stubs
826 if Nkind (D) in N_Body_Stub then
836 -- Missing stubs elsewhere
840 end Missing_Subunits;
842 ----------------------------
843 -- Output_Reference_Error --
844 ----------------------------
846 procedure Output_Reference_Error (M : String) is
848 -- Never issue messages for internal names, nor for renamings
850 if Is_Internal_Name (Chars (E1))
851 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
856 -- Don't output message for IN OUT formal unless we have the warning
857 -- flag specifically set. It is a bit odd to distinguish IN OUT
858 -- formals from other cases. This distinction is historical in
859 -- nature. Warnings for IN OUT formals were added fairly late.
861 if Ekind (E1) = E_In_Out_Parameter
862 and then not Check_Unreferenced_Formals
867 -- Other than accept case, post error on defining identifier
872 -- Accept case, find body formal to post the message
875 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
878 end Output_Reference_Error;
880 ----------------------------
881 -- Publicly_Referenceable --
882 ----------------------------
884 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
889 -- A formal parameter is never referenceable outside the body of its
890 -- subprogram or entry.
892 if Is_Formal (Ent) then
896 -- Examine parents to look for a library level package spec. But if
897 -- we find a body or block or other similar construct along the way,
898 -- we cannot be referenced.
905 -- If we get to top of tree, then publicly referenceable
910 -- If we reach a generic package declaration, then always
911 -- consider this referenceable, since any instantiation will
912 -- have access to the entities in the generic package. Note
913 -- that the package itself may not be instantiated, but then
914 -- we will get a warning for the package entity.
916 -- Note that generic formal parameters are themselves not
917 -- publicly referenceable in an instance, and warnings on them
920 when N_Generic_Package_Declaration =>
922 not Is_List_Member (Prev)
923 or else List_Containing (Prev)
924 /= Generic_Formal_Declarations (P);
926 -- Similarly, the generic formals of a generic subprogram are
929 when N_Generic_Subprogram_Declaration =>
930 if Is_List_Member (Prev)
931 and then List_Containing (Prev) =
932 Generic_Formal_Declarations (P)
939 -- If we reach a subprogram body, entity is not referenceable
940 -- unless it is the defining entity of the body. This will
941 -- happen, e.g. when a function is an attribute renaming that
942 -- is rewritten as a body.
944 when N_Subprogram_Body =>
945 if Ent /= Defining_Entity (P) then
951 -- If we reach any other body, definitely not referenceable
953 when N_Package_Body |
961 -- For all other cases, keep looking up tree
968 end Publicly_Referenceable;
970 ---------------------
971 -- Warnings_Off_E1 --
972 ---------------------
974 function Warnings_Off_E1 return Boolean is
976 return Has_Warnings_Off (E1T)
977 or else Has_Warnings_Off (Base_Type (E1T))
978 or else Warnings_Off_Check_Spec (E1);
981 -- Start of processing for Check_References
984 -- No messages if warnings are suppressed, or if we have detected any
985 -- real errors so far (this last check avoids junk messages resulting
986 -- from errors, e.g. a subunit that is not loaded).
988 if Warning_Mode = Suppress
989 or else Serious_Errors_Detected /= 0
994 -- We also skip the messages if any subunits were not loaded (see
995 -- comment in Sem_Ch10 to understand how this is set, and why it is
996 -- necessary to suppress the warnings in this case).
998 if Missing_Subunits then
1002 -- Otherwise loop through entities, looking for suspicious stuff
1004 E1 := First_Entity (E);
1005 while Present (E1) loop
1008 -- We are only interested in source entities. We also don't issue
1009 -- warnings within instances, since the proper place for such
1010 -- warnings is on the template when it is compiled.
1012 if Comes_From_Source (E1)
1013 and then Instantiation_Location (Sloc (E1)) = No_Location
1015 -- We are interested in variables and out/in-out parameters, but
1016 -- we exclude protected types, too complicated to worry about.
1018 if Ekind (E1) = E_Variable
1020 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1021 and then not Is_Protected_Type (Current_Scope))
1023 -- Case of an unassigned variable
1025 -- First gather any Unset_Reference indication for E1. In the
1026 -- case of a parameter, it is the Spec_Entity that is relevant.
1028 if Ekind (E1) = E_Out_Parameter
1029 and then Present (Spec_Entity (E1))
1031 UR := Unset_Reference (Spec_Entity (E1));
1033 UR := Unset_Reference (E1);
1036 -- Special processing for access types
1039 and then Is_Access_Type (E1T)
1041 -- For access types, the only time we made a UR entry was
1042 -- for a dereference, and so we post the appropriate warning
1043 -- here (note that the dereference may not be explicit in
1044 -- the source, for example in the case of a dispatching call
1045 -- with an anonymous access controlling formal, or of an
1046 -- assignment of a pointer involving discriminant check on
1047 -- the designated object).
1049 if not Warnings_Off_E1 then
1050 Error_Msg_NE ("?& may be null!", UR, E1);
1055 -- Case of variable that could be a constant. Note that we
1056 -- never signal such messages for generic package entities,
1057 -- since a given instance could have modifications outside
1060 elsif Warn_On_Constant
1061 and then (Ekind (E1) = E_Variable
1062 and then Has_Initial_Value (E1))
1063 and then Never_Set_In_Source_Check_Spec (E1)
1064 and then not Address_Taken (E1)
1065 and then not Generic_Package_Spec_Entity (E1)
1067 -- A special case, if this variable is volatile and not
1068 -- imported, it is not helpful to tell the programmer
1069 -- to mark the variable as constant, since this would be
1070 -- illegal by virtue of RM C.6(13).
1072 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1073 and then not Is_Imported (E1)
1076 ("?& is not modified, volatile has no effect!", E1);
1078 -- Another special case, Exception_Occurrence, this catches
1079 -- the case of exception choice (and a bit more too, but not
1080 -- worth doing more investigation here).
1082 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1085 -- Here we give the warning if referenced and no pragma
1086 -- Unreferenced or Unmodified is present.
1091 if Ekind (E1) = E_Variable then
1092 if Referenced_Check_Spec (E1)
1093 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1094 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1096 if not Warnings_Off_E1 then
1097 Error_Msg_N -- CODEFIX
1098 ("?& is not modified, "
1099 & "could be declared constant!",
1106 -- Other cases of a variable or parameter never set in source
1108 elsif Never_Set_In_Source_Check_Spec (E1)
1110 -- No warning if warning for this case turned off
1112 and then Warn_On_No_Value_Assigned
1114 -- No warning if address taken somewhere
1116 and then not Address_Taken (E1)
1118 -- No warning if explicit initial value
1120 and then not Has_Initial_Value (E1)
1122 -- No warning for generic package spec entities, since we
1123 -- might set them in a child unit or something like that
1125 and then not Generic_Package_Spec_Entity (E1)
1127 -- No warning if fully initialized type, except that for
1128 -- this purpose we do not consider access types to qualify
1129 -- as fully initialized types (relying on an access type
1130 -- variable being null when it is never set is a bit odd!)
1132 -- Also we generate warning for an out parameter that is
1133 -- never referenced, since again it seems odd to rely on
1134 -- default initialization to set an out parameter value.
1136 and then (Is_Access_Type (E1T)
1137 or else Ekind (E1) = E_Out_Parameter
1138 or else not Is_Fully_Initialized_Type (E1T))
1140 -- Do not output complaint about never being assigned a
1141 -- value if a pragma Unmodified applies to the variable
1142 -- we are examining, or if it is a parameter, if there is
1143 -- a pragma Unreferenced for the corresponding spec, or
1144 -- if the type is marked as having unreferenced objects.
1145 -- The last is a little peculiar, but better too few than
1146 -- too many warnings in this situation.
1148 if Has_Pragma_Unreferenced_Objects (E1T)
1149 or else Has_Pragma_Unmodified_Check_Spec (E1)
1153 -- IN OUT parameter case where parameter is referenced. We
1154 -- separate this out, since this is the case where we delay
1155 -- output of the warning until more information is available
1156 -- (about use in an instantiation or address being taken).
1158 elsif Ekind (E1) = E_In_Out_Parameter
1159 and then Referenced_Check_Spec (E1)
1161 -- Suppress warning if private type, and the procedure
1162 -- has a separate declaration in a different unit. This
1163 -- is the case where the client of a package sees only
1164 -- the private type, and it may be quite reasonable
1165 -- for the logical view to be IN OUT, even if the
1166 -- implementation ends up using access types or some
1167 -- other method to achieve the local effect of a
1168 -- modification. On the other hand if the spec and body
1169 -- are in the same unit, we are in the package body and
1170 -- there we have less excuse for a junk IN OUT parameter.
1172 if Has_Private_Declaration (E1T)
1173 and then Present (Spec_Entity (E1))
1174 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1178 -- Suppress warning for any parameter of a dispatching
1179 -- operation, since it is quite reasonable to have an
1180 -- operation that is overridden, and for some subclasses
1181 -- needs the formal to be IN OUT and for others happens
1182 -- not to assign it.
1184 elsif Is_Dispatching_Operation
1185 (Scope (Goto_Spec_Entity (E1)))
1189 -- Suppress warning if composite type contains any access
1190 -- component, since the logical effect of modifying a
1191 -- parameter may be achieved by modifying a referenced
1194 elsif Is_Composite_Type (E1T)
1195 and then Has_Access_Values (E1T)
1199 -- Suppress warning on formals of an entry body. All
1200 -- references are attached to the formal in the entry
1201 -- declaration, which are marked Is_Entry_Formal.
1203 elsif Ekind (Scope (E1)) = E_Entry
1204 and then not Is_Entry_Formal (E1)
1208 -- OK, looks like warning for an IN OUT parameter that
1209 -- could be IN makes sense, but we delay the output of
1210 -- the warning, pending possibly finding out later on
1211 -- that the associated subprogram is used as a generic
1212 -- actual, or its address/access is taken. In these two
1213 -- cases, we suppress the warning because the context may
1214 -- force use of IN OUT, even if in this particular case
1215 -- the formal is not modified.
1218 In_Out_Warnings.Append (E1);
1221 -- Other cases of formals
1223 elsif Is_Formal (E1) then
1224 if not Is_Trivial_Subprogram (Scope (E1)) then
1225 if Referenced_Check_Spec (E1) then
1226 if not Has_Pragma_Unmodified_Check_Spec (E1)
1227 and then not Warnings_Off_E1
1229 Output_Reference_Error
1230 ("?formal parameter& is read but "
1231 & "never assigned!");
1234 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1235 and then not Warnings_Off_E1
1237 Output_Reference_Error
1238 ("?formal parameter& is not referenced!");
1245 if Referenced (E1) then
1246 if not Has_Unmodified (E1)
1247 and then not Warnings_Off_E1
1249 Output_Reference_Error
1250 ("?variable& is read but never assigned!");
1253 elsif not Has_Unreferenced (E1)
1254 and then not Warnings_Off_E1
1256 Output_Reference_Error -- CODEFIX
1257 ("?variable& is never read and never assigned!");
1260 -- Deal with special case where this variable is hidden
1261 -- by a loop variable.
1263 if Ekind (E1) = E_Variable
1264 and then Present (Hiding_Loop_Variable (E1))
1265 and then not Warnings_Off_E1
1268 ("?for loop implicitly declares loop variable!",
1269 Hiding_Loop_Variable (E1));
1271 Error_Msg_Sloc := Sloc (E1);
1273 ("\?declaration hides & declared#!",
1274 Hiding_Loop_Variable (E1));
1281 -- Check for unset reference
1283 if Warn_On_No_Value_Assigned and then Present (UR) then
1285 -- For other than access type, go back to original node to
1286 -- deal with case where original unset reference has been
1287 -- rewritten during expansion.
1289 -- In some cases, the original node may be a type conversion
1290 -- or qualification, and in this case we want the object
1293 UR := Original_Node (UR);
1294 while Nkind (UR) = N_Type_Conversion
1295 or else Nkind (UR) = N_Qualified_Expression
1297 UR := Expression (UR);
1300 -- Here we issue the warning, all checks completed
1302 -- If we have a return statement, this was a case of an OUT
1303 -- parameter not being set at the time of the return. (Note:
1304 -- it can't be N_Extended_Return_Statement, because those
1305 -- are only for functions, and functions do not allow OUT
1308 if not Is_Trivial_Subprogram (Scope (E1)) then
1309 if Nkind (UR) = N_Simple_Return_Statement
1310 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1312 if not Warnings_Off_E1 then
1314 ("?OUT parameter& not set before return", UR, E1);
1317 -- If the unset reference is a selected component
1318 -- prefix from source, mention the component as well.
1319 -- If the selected component comes from expansion, all
1320 -- we know is that the entity is not fully initialized
1321 -- at the point of the reference. Locate a random
1322 -- uninitialized component to get a better message.
1324 elsif Nkind (Parent (UR)) = N_Selected_Component then
1325 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1327 if not Comes_From_Source (Parent (UR)) then
1332 Comp := First_Entity (E1T);
1333 while Present (Comp) loop
1334 if Ekind (Comp) = E_Component
1335 and then Nkind (Parent (Comp)) =
1336 N_Component_Declaration
1337 and then No (Expression (Parent (Comp)))
1339 Error_Msg_Node_2 := Comp;
1348 -- Issue proper warning. This is a case of referencing
1349 -- a variable before it has been explicitly assigned.
1350 -- For access types, UR was only set for dereferences,
1351 -- so the issue is that the value may be null.
1353 if not Is_Trivial_Subprogram (Scope (E1)) then
1354 if not Warnings_Off_E1 then
1355 if Is_Access_Type (Etype (Parent (UR))) then
1356 Error_Msg_N ("?`&.&` may be null!", UR);
1359 ("?`&.&` may be referenced before "
1360 & "it has a value!", UR);
1365 -- All other cases of unset reference active
1367 elsif not Warnings_Off_E1 then
1369 ("?& may be referenced before it has a value!",
1378 -- Then check for unreferenced entities. Note that we are only
1379 -- interested in entities whose Referenced flag is not set.
1381 if not Referenced_Check_Spec (E1)
1383 -- If Referenced_As_LHS is set, then that's still interesting
1384 -- (potential "assigned but never read" case), but not if we
1385 -- have pragma Unreferenced, which cancels this warning.
1387 and then (not Referenced_As_LHS_Check_Spec (E1)
1388 or else not Has_Unreferenced (E1))
1390 -- Check that warnings on unreferenced entities are enabled
1393 ((Check_Unreferenced and then not Is_Formal (E1))
1395 -- Case of warning on unreferenced formal
1398 (Check_Unreferenced_Formals and then Is_Formal (E1))
1400 -- Case of warning on unread variables modified by an
1401 -- assignment, or an OUT parameter if it is the only one.
1404 (Warn_On_Modified_Unread
1405 and then Referenced_As_LHS_Check_Spec (E1))
1407 -- Case of warning on any unread OUT parameter (note
1408 -- such indications are only set if the appropriate
1409 -- warning options were set, so no need to recheck here.)
1412 Referenced_As_Out_Parameter_Check_Spec (E1))
1414 -- All other entities, including local packages that cannot be
1415 -- referenced from elsewhere, including those declared within a
1418 and then (Is_Object (E1)
1422 Ekind (E1) = E_Label
1424 Ekind (E1) = E_Exception
1426 Ekind (E1) = E_Named_Integer
1428 Ekind (E1) = E_Named_Real
1430 Is_Overloadable (E1)
1432 -- Package case, if the main unit is a package spec
1433 -- or generic package spec, then there may be a
1434 -- corresponding body that references this package
1435 -- in some other file. Otherwise we can be sure
1436 -- that there is no other reference.
1439 (Ekind (E1) = E_Package
1441 not Is_Package_Or_Generic_Package
1442 (Cunit_Entity (Current_Sem_Unit))))
1444 -- Exclude instantiations, since there is no reason why every
1445 -- entity in an instantiation should be referenced.
1447 and then Instantiation_Location (Sloc (E1)) = No_Location
1449 -- Exclude formal parameters from bodies if the corresponding
1450 -- spec entity has been referenced in the case where there is
1453 and then not (Is_Formal (E1)
1454 and then Ekind (Scope (E1)) = E_Subprogram_Body
1455 and then Present (Spec_Entity (E1))
1456 and then Referenced (Spec_Entity (E1)))
1458 -- Consider private type referenced if full view is referenced.
1459 -- If there is not full view, this is a generic type on which
1460 -- warnings are also useful.
1463 not (Is_Private_Type (E1)
1464 and then Present (Full_View (E1))
1465 and then Referenced (Full_View (E1)))
1467 -- Don't worry about full view, only about private type
1469 and then not Has_Private_Declaration (E1)
1471 -- Eliminate dispatching operations from consideration, we
1472 -- cannot tell if these are referenced or not in any easy
1473 -- manner (note this also catches Adjust/Finalize/Initialize).
1475 and then not Is_Dispatching_Operation (E1)
1477 -- Check entity that can be publicly referenced (we do not give
1478 -- messages for such entities, since there could be other
1479 -- units, not involved in this compilation, that contain
1480 -- relevant references.
1482 and then not Publicly_Referenceable (E1)
1484 -- Class wide types are marked as source entities, but they are
1485 -- not really source entities, and are always created, so we do
1486 -- not care if they are not referenced.
1488 and then Ekind (E1) /= E_Class_Wide_Type
1490 -- Objects other than parameters of task types are allowed to
1491 -- be non-referenced, since they start up tasks!
1493 and then ((Ekind (E1) /= E_Variable
1494 and then Ekind (E1) /= E_Constant
1495 and then Ekind (E1) /= E_Component)
1496 or else not Is_Task_Type (E1T))
1498 -- For subunits, only place warnings on the main unit itself,
1499 -- since parent units are not completely compiled.
1501 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1502 or else Get_Source_Unit (E1) = Main_Unit)
1504 -- No warning on a return object, because these are often
1505 -- created with a single expression and an implicit return.
1506 -- If the object is a variable there will be a warning
1507 -- indicating that it could be declared constant.
1510 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1512 -- Suppress warnings in internal units if not in -gnatg mode
1513 -- (these would be junk warnings for an applications program,
1514 -- since they refer to problems in internal units).
1517 or else not Is_Internal_File_Name
1518 (Unit_File_Name (Get_Source_Unit (E1)))
1520 -- We do not immediately flag the error. This is because we
1521 -- have not expanded generic bodies yet, and they may have
1522 -- the missing reference. So instead we park the entity on a
1523 -- list, for later processing. However for the case of an
1524 -- accept statement we want to output messages now, since
1525 -- we know we already have all information at hand, and we
1526 -- also want to have separate warnings for each accept
1527 -- statement for the same entry.
1529 if Present (Anod) then
1530 pragma Assert (Is_Formal (E1));
1532 -- The unreferenced entity is E1, but post the warning
1533 -- on the body entity for this accept statement.
1535 if not Warnings_Off_E1 then
1536 Warn_On_Unreferenced_Entity
1537 (E1, Body_Formal (E1, Accept_Statement => Anod));
1540 elsif not Warnings_Off_E1 then
1541 Unreferenced_Entities.Append (E1);
1545 -- Generic units are referenced in the generic body, but if they
1546 -- are not public and never instantiated we want to force a
1547 -- warning on them. We treat them as redundant constructs to
1550 elsif Is_Generic_Subprogram (E1)
1551 and then not Is_Instantiated (E1)
1552 and then not Publicly_Referenceable (E1)
1553 and then Instantiation_Depth (Sloc (E1)) = 0
1554 and then Warn_On_Redundant_Constructs
1556 if not Warnings_Off_E1 then
1557 Unreferenced_Entities.Append (E1);
1559 -- Force warning on entity
1561 Set_Referenced (E1, False);
1566 -- Recurse into nested package or block. Do not recurse into a formal
1567 -- package, because the corresponding body is not analyzed.
1570 if (Is_Package_Or_Generic_Package (E1)
1571 and then Nkind (Parent (E1)) = N_Package_Specification
1573 Nkind (Original_Node (Unit_Declaration_Node (E1)))
1574 /= N_Formal_Package_Declaration)
1576 or else Ekind (E1) = E_Block
1578 Check_References (E1);
1583 end Check_References;
1585 ---------------------------
1586 -- Check_Unset_Reference --
1587 ---------------------------
1589 procedure Check_Unset_Reference (N : Node_Id) is
1590 Typ : constant Entity_Id := Etype (N);
1592 function Is_OK_Fully_Initialized return Boolean;
1593 -- This function returns true if the given node N is fully initialized
1594 -- so that the reference is safe as far as this routine is concerned.
1595 -- Safe generally means that the type of N is a fully initialized type.
1596 -- The one special case is that for access types, which are always fully
1597 -- initialized, we don't consider a dereference OK since it will surely
1598 -- be dereferencing a null value, which won't do.
1600 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1601 -- Used to test indexed or selected component or slice to see if the
1602 -- evaluation of the prefix depends on a dereference, and if so, returns
1603 -- True, in which case we always check the prefix, even if we know that
1604 -- the referenced component is initialized. Pref is the prefix to test.
1606 -----------------------------
1607 -- Is_OK_Fully_Initialized --
1608 -----------------------------
1610 function Is_OK_Fully_Initialized return Boolean is
1612 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1615 return Is_Fully_Initialized_Type (Typ);
1617 end Is_OK_Fully_Initialized;
1619 ----------------------------
1620 -- Prefix_Has_Dereference --
1621 ----------------------------
1623 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1625 -- If prefix is of an access type, it certainly needs a dereference
1627 if Is_Access_Type (Etype (Pref)) then
1630 -- If prefix is explicit dereference, that's a dereference for sure
1632 elsif Nkind (Pref) = N_Explicit_Dereference then
1635 -- If prefix is itself a component reference or slice check prefix
1637 elsif Nkind (Pref) = N_Slice
1638 or else Nkind (Pref) = N_Indexed_Component
1639 or else Nkind (Pref) = N_Selected_Component
1641 return Prefix_Has_Dereference (Prefix (Pref));
1643 -- All other cases do not involve a dereference
1648 end Prefix_Has_Dereference;
1650 -- Start of processing for Check_Unset_Reference
1653 -- Nothing to do if warnings suppressed
1655 if Warning_Mode = Suppress then
1659 -- Ignore reference unless it comes from source. Almost always if we
1660 -- have a reference from generated code, it is bogus (e.g. calls to init
1661 -- procs to set default discriminant values).
1663 if not Comes_From_Source (N) then
1667 -- Otherwise see what kind of node we have. If the entity already has an
1668 -- unset reference, it is not necessarily the earliest in the text,
1669 -- because resolution of the prefix of selected components is completed
1670 -- before the resolution of the selected component itself. As a result,
1671 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1672 -- in right-to-left order. If there is already an unset reference, we
1673 -- check whether N is earlier before proceeding.
1677 -- For identifier or expanded name, examine the entity involved
1679 when N_Identifier | N_Expanded_Name =>
1681 E : constant Entity_Id := Entity (N);
1684 if (Ekind (E) = E_Variable
1686 Ekind (E) = E_Out_Parameter)
1687 and then Never_Set_In_Source_Check_Spec (E)
1688 and then not Has_Initial_Value (E)
1689 and then (No (Unset_Reference (E))
1691 Earlier_In_Extended_Unit
1692 (Sloc (N), Sloc (Unset_Reference (E))))
1693 and then not Has_Pragma_Unmodified_Check_Spec (E)
1694 and then not Warnings_Off_Check_Spec (E)
1696 -- We may have an unset reference. The first test is whether
1697 -- this is an access to a discriminant of a record or a
1698 -- component with default initialization. Both of these
1699 -- cases can be ignored, since the actual object that is
1700 -- referenced is definitely initialized. Note that this
1701 -- covers the case of reading discriminants of an OUT
1702 -- parameter, which is OK even in Ada 83.
1704 -- Note that we are only interested in a direct reference to
1705 -- a record component here. If the reference is through an
1706 -- access type, then the access object is being referenced,
1707 -- not the record, and still deserves an unset reference.
1709 if Nkind (Parent (N)) = N_Selected_Component
1710 and not Is_Access_Type (Typ)
1713 ES : constant Entity_Id :=
1714 Entity (Selector_Name (Parent (N)));
1716 if Ekind (ES) = E_Discriminant
1718 (Present (Declaration_Node (ES))
1720 Present (Expression (Declaration_Node (ES))))
1727 -- Exclude fully initialized types
1729 if Is_OK_Fully_Initialized then
1733 -- Here we have a potential unset reference. But before we
1734 -- get worried about it, we have to make sure that the
1735 -- entity declaration is in the same procedure as the
1736 -- reference, since if they are in separate procedures, then
1737 -- we have no idea about sequential execution.
1739 -- The tests in the loop below catch all such cases, but do
1740 -- allow the reference to appear in a loop, block, or
1741 -- package spec that is nested within the declaring scope.
1742 -- As always, it is possible to construct cases where the
1743 -- warning is wrong, that is why it is a warning!
1745 Potential_Unset_Reference : declare
1747 SE : constant Entity_Id := Scope (E);
1749 function Within_Postcondition return Boolean;
1750 -- Returns True iff N is within a Postcondition or
1751 -- Ensures component in a Contract_Case or Test_Case.
1753 --------------------------
1754 -- Within_Postcondition --
1755 --------------------------
1757 function Within_Postcondition return Boolean is
1762 while Present (Nod) loop
1763 if Nkind (Nod) = N_Pragma
1764 and then Pragma_Name (Nod) = Name_Postcondition
1768 elsif Present (Parent (Nod)) then
1771 if Nkind (P) = N_Pragma
1773 (Pragma_Name (P) = Name_Contract_Case
1775 Pragma_Name (P) = Name_Test_Case)
1777 Nod = Get_Ensures_From_CTC_Pragma (P)
1783 Nod := Parent (Nod);
1787 end Within_Postcondition;
1789 -- Start of processing for Potential_Unset_Reference
1792 SR := Current_Scope;
1794 if SR = Standard_Standard
1795 or else Is_Subprogram (SR)
1796 or else Is_Concurrent_Body (SR)
1797 or else Is_Concurrent_Type (SR)
1805 -- Case of reference has an access type. This is a
1806 -- special case since access types are always set to null
1807 -- so cannot be truly uninitialized, but we still want to
1808 -- warn about cases of obvious null dereference.
1810 if Is_Access_Type (Typ) then
1811 Access_Type_Case : declare
1815 (N : Node_Id) return Traverse_Result;
1816 -- Process function for instantiation of Traverse
1817 -- below. Checks if N contains reference to E other
1818 -- than a dereference.
1820 function Ref_In (Nod : Node_Id) return Boolean;
1821 -- Determines whether Nod contains a reference to
1822 -- the entity E that is not a dereference.
1829 (N : Node_Id) return Traverse_Result
1832 if Is_Entity_Name (N)
1833 and then Entity (N) = E
1834 and then not Is_Dereferenced (N)
1846 function Ref_In (Nod : Node_Id) return Boolean is
1847 function Traverse is new Traverse_Func (Process);
1849 return Traverse (Nod) = Abandon;
1852 -- Start of processing for Access_Type_Case
1855 -- Don't bother if we are inside an instance, since
1856 -- the compilation of the generic template is where
1857 -- the warning should be issued.
1863 -- Don't bother if this is not the main unit. If we
1864 -- try to give this warning for with'ed units, we
1865 -- get some false positives, since we do not record
1866 -- references in other units.
1868 if not In_Extended_Main_Source_Unit (E)
1870 not In_Extended_Main_Source_Unit (N)
1875 -- We are only interested in dereferences
1877 if not Is_Dereferenced (N) then
1881 -- One more check, don't bother with references
1882 -- that are inside conditional statements or WHILE
1883 -- loops if the condition references the entity in
1884 -- question. This avoids most false positives.
1891 if (Nkind (P) = N_If_Statement
1893 Nkind (P) = N_Elsif_Part)
1894 and then Ref_In (Condition (P))
1898 elsif Nkind (P) = N_Loop_Statement
1899 and then Present (Iteration_Scheme (P))
1901 Ref_In (Condition (Iteration_Scheme (P)))
1906 end Access_Type_Case;
1909 -- One more check, don't bother if we are within a
1910 -- postcondition, since the expression occurs in a
1911 -- place unrelated to the actual test.
1913 if not Within_Postcondition then
1915 -- Here we definitely have a case for giving a warning
1916 -- for a reference to an unset value. But we don't
1917 -- give the warning now. Instead set Unset_Reference
1918 -- in the identifier involved. The reason for this is
1919 -- that if we find the variable is never ever assigned
1920 -- a value then that warning is more important and
1921 -- there is no point in giving the reference warning.
1923 -- If this is an identifier, set the field directly
1925 if Nkind (N) = N_Identifier then
1926 Set_Unset_Reference (E, N);
1928 -- Otherwise it is an expanded name, so set the field
1929 -- of the actual identifier for the reference.
1932 Set_Unset_Reference (E, Selector_Name (N));
1935 end Potential_Unset_Reference;
1939 -- Indexed component or slice
1941 when N_Indexed_Component | N_Slice =>
1943 -- If prefix does not involve dereferencing an access type, then
1944 -- we know we are OK if the component type is fully initialized,
1945 -- since the component will have been set as part of the default
1948 if not Prefix_Has_Dereference (Prefix (N))
1949 and then Is_OK_Fully_Initialized
1953 -- Look at prefix in access type case, or if the component is not
1954 -- fully initialized.
1957 Check_Unset_Reference (Prefix (N));
1962 when N_Selected_Component =>
1964 Pref : constant Node_Id := Prefix (N);
1965 Ent : constant Entity_Id := Entity (Selector_Name (N));
1968 -- If prefix involves dereferencing an access type, always
1969 -- check the prefix, since the issue then is whether this
1970 -- access value is null.
1972 if Prefix_Has_Dereference (Pref) then
1975 -- Always go to prefix if no selector entity is set. Can this
1976 -- happen in the normal case? Not clear, but it definitely can
1977 -- happen in error cases.
1982 -- For a record component, check some cases where we have
1983 -- reasonable cause to consider that the component is known to
1984 -- be or probably is initialized. In this case, we don't care
1985 -- if the prefix itself was explicitly initialized.
1987 -- Discriminants are always considered initialized
1989 elsif Ekind (Ent) = E_Discriminant then
1992 -- An explicitly initialized component is certainly initialized
1994 elsif Nkind (Parent (Ent)) = N_Component_Declaration
1995 and then Present (Expression (Parent (Ent)))
1999 -- A fully initialized component is initialized
2001 elsif Is_OK_Fully_Initialized then
2005 -- If none of those cases apply, check the record type prefix
2007 Check_Unset_Reference (Pref);
2010 -- For type conversions or qualifications examine the expression
2012 when N_Type_Conversion | N_Qualified_Expression =>
2013 Check_Unset_Reference (Expression (N));
2015 -- For explicit dereference, always check prefix, which will generate
2016 -- an unset reference (since this is a case of dereferencing null).
2018 when N_Explicit_Dereference =>
2019 Check_Unset_Reference (Prefix (N));
2021 -- All other cases are not cases of an unset reference
2027 end Check_Unset_Reference;
2029 ------------------------
2030 -- Check_Unused_Withs --
2031 ------------------------
2033 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2039 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2040 -- This is needed for checking the special renaming case
2042 procedure Check_One_Unit (Unit : Unit_Number_Type);
2043 -- Subsidiary procedure, performs checks for specified unit
2045 --------------------
2046 -- Check_One_Unit --
2047 --------------------
2049 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2050 Is_Visible_Renaming : Boolean := False;
2053 procedure Check_Inner_Package (Pack : Entity_Id);
2054 -- Pack is a package local to a unit in a with_clause. Both the unit
2055 -- and Pack are referenced. If none of the entities in Pack are
2056 -- referenced, then the only occurrence of Pack is in a USE clause
2057 -- or a pragma, and a warning is worthwhile as well.
2059 function Check_System_Aux return Boolean;
2060 -- Before giving a warning on a with_clause for System, check whether
2061 -- a system extension is present.
2063 function Find_Package_Renaming
2065 L : Entity_Id) return Entity_Id;
2066 -- The only reference to a context unit may be in a renaming
2067 -- declaration. If this renaming declares a visible entity, do not
2068 -- warn that the context clause could be moved to the body, because
2069 -- the renaming may be intended to re-export the unit.
2071 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2072 -- This function determines if a package has any visible entities.
2073 -- True is returned if there is at least one declared visible entity,
2074 -- otherwise False is returned (e.g. case of only pragmas present).
2076 -------------------------
2077 -- Check_Inner_Package --
2078 -------------------------
2080 procedure Check_Inner_Package (Pack : Entity_Id) is
2082 Un : constant Node_Id := Sinfo.Unit (Cnode);
2084 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2085 -- If N is a use_clause for Pack, emit warning
2087 procedure Check_Use_Clauses is new
2088 Traverse_Proc (Check_Use_Clause);
2090 ----------------------
2091 -- Check_Use_Clause --
2092 ----------------------
2094 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2098 if Nkind (N) = N_Use_Package_Clause then
2099 Nam := First (Names (N));
2100 while Present (Nam) loop
2101 if Entity (Nam) = Pack then
2102 Error_Msg_Qual_Level := 1;
2103 Error_Msg_NE -- CODEFIX
2104 ("?no entities of package& are referenced!",
2106 Error_Msg_Qual_Level := 0;
2114 end Check_Use_Clause;
2116 -- Start of processing for Check_Inner_Package
2119 E := First_Entity (Pack);
2120 while Present (E) loop
2121 if Referenced_Check_Spec (E) then
2128 -- No entities of the package are referenced. Check whether the
2129 -- reference to the package itself is a use clause, and if so
2130 -- place a warning on it.
2132 Check_Use_Clauses (Un);
2133 end Check_Inner_Package;
2135 ----------------------
2136 -- Check_System_Aux --
2137 ----------------------
2139 function Check_System_Aux return Boolean is
2143 if Chars (Lunit) = Name_System
2144 and then Scope (Lunit) = Standard_Standard
2145 and then Present_System_Aux
2147 Ent := First_Entity (System_Aux_Id);
2148 while Present (Ent) loop
2149 if Referenced_Check_Spec (Ent) then
2158 end Check_System_Aux;
2160 ---------------------------
2161 -- Find_Package_Renaming --
2162 ---------------------------
2164 function Find_Package_Renaming
2166 L : Entity_Id) return Entity_Id
2172 Is_Visible_Renaming := False;
2174 E1 := First_Entity (P);
2175 while Present (E1) loop
2176 if Ekind (E1) = E_Package
2177 and then Renamed_Object (E1) = L
2179 Is_Visible_Renaming := not Is_Hidden (E1);
2182 elsif Ekind (E1) = E_Package
2183 and then No (Renamed_Object (E1))
2184 and then not Is_Generic_Instance (E1)
2186 R := Find_Package_Renaming (E1, L);
2189 Is_Visible_Renaming := not Is_Hidden (R);
2198 end Find_Package_Renaming;
2200 --------------------------
2201 -- Has_Visible_Entities --
2202 --------------------------
2204 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2208 -- If unit in context is not a package, it is a subprogram that
2209 -- is not called or a generic unit that is not instantiated
2210 -- in the current unit, and warning is appropriate.
2212 if Ekind (P) /= E_Package then
2216 -- If unit comes from a limited_with clause, look for declaration
2217 -- of shadow entities.
2219 if Present (Limited_View (P)) then
2220 E := First_Entity (Limited_View (P));
2222 E := First_Entity (P);
2226 and then E /= First_Private_Entity (P)
2228 if Comes_From_Source (E)
2229 or else Present (Limited_View (P))
2238 end Has_Visible_Entities;
2240 -- Start of processing for Check_One_Unit
2243 Cnode := Cunit (Unit);
2245 -- Only do check in units that are part of the extended main unit.
2246 -- This is actually a necessary restriction, because in the case of
2247 -- subprogram acting as its own specification, there can be with's in
2248 -- subunits that we will not see.
2250 if not In_Extended_Main_Source_Unit (Cnode) then
2253 -- In configurable run time mode, we remove the bodies of non-inlined
2254 -- subprograms, which may lead to spurious warnings, which are
2255 -- clearly undesirable.
2257 elsif Configurable_Run_Time_Mode
2258 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2263 -- Loop through context items in this unit
2265 Item := First (Context_Items (Cnode));
2266 while Present (Item) loop
2267 if Nkind (Item) = N_With_Clause
2268 and then not Implicit_With (Item)
2269 and then In_Extended_Main_Source_Unit (Item)
2271 Lunit := Entity (Name (Item));
2273 -- Check if this unit is referenced (skip the check if this
2274 -- is explicitly marked by a pragma Unreferenced).
2276 if not Referenced (Lunit)
2277 and then not Has_Unreferenced (Lunit)
2279 -- Suppress warnings in internal units if not in -gnatg mode
2280 -- (these would be junk warnings for an application program,
2281 -- since they refer to problems in internal units).
2284 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2286 -- Here we definitely have a non-referenced unit. If it
2287 -- is the special call for a spec unit, then just set the
2288 -- flag to be read later.
2290 if Unit = Spec_Unit then
2291 Set_Unreferenced_In_Spec (Item);
2293 -- Otherwise simple unreferenced message, but skip this
2294 -- if no visible entities, because that is most likely a
2295 -- case where warning would be false positive (e.g. a
2296 -- package with only a linker options pragma and nothing
2297 -- else or a pragma elaborate with a body library task).
2299 elsif Has_Visible_Entities (Entity (Name (Item))) then
2300 Error_Msg_N -- CODEFIX
2301 ("?unit& is not referenced!", Name (Item));
2305 -- If main unit is a renaming of this unit, then we consider
2306 -- the with to be OK (obviously it is needed in this case!)
2307 -- This may be transitive: the unit in the with_clause may
2308 -- itself be a renaming, in which case both it and the main
2309 -- unit rename the same ultimate package.
2311 elsif Present (Renamed_Entity (Munite))
2313 (Renamed_Entity (Munite) = Lunit
2314 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2318 -- If this unit is referenced, and it is a package, we do
2319 -- another test, to see if any of the entities in the package
2320 -- are referenced. If none of the entities are referenced, we
2321 -- still post a warning. This occurs if the only use of the
2322 -- package is in a use clause, or in a package renaming
2323 -- declaration. This check is skipped for packages that are
2324 -- renamed in a spec, since the entities in such a package are
2325 -- visible to clients via the renaming.
2327 elsif Ekind (Lunit) = E_Package
2328 and then not Renamed_In_Spec (Lunit)
2330 -- If Is_Instantiated is set, it means that the package is
2331 -- implicitly instantiated (this is the case of parent
2332 -- instance or an actual for a generic package formal), and
2333 -- this counts as a reference.
2335 if Is_Instantiated (Lunit) then
2338 -- If no entities in package, and there is a pragma
2339 -- Elaborate_Body present, then assume that this with is
2340 -- done for purposes of this elaboration.
2342 elsif No (First_Entity (Lunit))
2343 and then Has_Pragma_Elaborate_Body (Lunit)
2347 -- Otherwise see if any entities have been referenced
2350 if Limited_Present (Item) then
2351 Ent := First_Entity (Limited_View (Lunit));
2353 Ent := First_Entity (Lunit);
2357 -- No more entities, and we did not find one that was
2358 -- referenced. Means we have a definite case of a with
2359 -- none of whose entities was referenced.
2363 -- If in spec, just set the flag
2365 if Unit = Spec_Unit then
2366 Set_No_Entities_Ref_In_Spec (Item);
2368 elsif Check_System_Aux then
2371 -- Else give the warning
2375 Has_Unreferenced (Entity (Name (Item)))
2377 Error_Msg_N -- CODEFIX
2378 ("?no entities of & are referenced!",
2382 -- Look for renamings of this package, and flag
2383 -- them as well. If the original package has
2384 -- warnings off, we suppress the warning on the
2385 -- renaming as well.
2387 Pack := Find_Package_Renaming (Munite, Lunit);
2390 and then not Has_Warnings_Off (Lunit)
2391 and then not Has_Unreferenced (Pack)
2393 Error_Msg_NE -- CODEFIX
2394 ("?no entities of & are referenced!",
2395 Unit_Declaration_Node (Pack),
2402 -- Case of entity being referenced. The reference may
2403 -- come from a limited_with_clause, in which case the
2404 -- limited view of the entity carries the flag.
2406 elsif Referenced_Check_Spec (Ent)
2407 or else Referenced_As_LHS_Check_Spec (Ent)
2408 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2410 (From_With_Type (Ent)
2411 and then Is_Incomplete_Type (Ent)
2412 and then Present (Non_Limited_View (Ent))
2413 and then Referenced (Non_Limited_View (Ent)))
2415 -- This means that the with is indeed fine, in that
2416 -- it is definitely needed somewhere, and we can
2417 -- quit worrying about this one...
2419 -- Except for one little detail: if either of the
2420 -- flags was set during spec processing, this is
2421 -- where we complain that the with could be moved
2422 -- from the spec. If the spec contains a visible
2423 -- renaming of the package, inhibit warning to move
2424 -- with_clause to body.
2426 if Ekind (Munite) = E_Package_Body then
2428 Find_Package_Renaming
2429 (Spec_Entity (Munite), Lunit);
2434 -- If a renaming is present in the spec do not warn
2435 -- because the body or child unit may depend on it.
2438 and then Renamed_Entity (Pack) = Lunit
2442 elsif Unreferenced_In_Spec (Item) then
2443 Error_Msg_N -- CODEFIX
2444 ("?unit& is not referenced in spec!",
2447 elsif No_Entities_Ref_In_Spec (Item) then
2448 Error_Msg_N -- CODEFIX
2449 ("?no entities of & are referenced in spec!",
2453 if Ekind (Ent) = E_Package then
2454 Check_Inner_Package (Ent);
2460 if not Is_Visible_Renaming then
2461 Error_Msg_N -- CODEFIX
2462 ("\?with clause might be moved to body!",
2468 -- Move to next entity to continue search
2476 -- For a generic package, the only interesting kind of
2477 -- reference is an instantiation, since entities cannot be
2478 -- referenced directly.
2480 elsif Is_Generic_Unit (Lunit) then
2482 -- Unit was never instantiated, set flag for case of spec
2483 -- call, or give warning for normal call.
2485 if not Is_Instantiated (Lunit) then
2486 if Unit = Spec_Unit then
2487 Set_Unreferenced_In_Spec (Item);
2489 Error_Msg_N -- CODEFIX
2490 ("?unit& is never instantiated!", Name (Item));
2493 -- If unit was indeed instantiated, make sure that flag is
2494 -- not set showing it was uninstantiated in the spec, and if
2495 -- so, give warning.
2497 elsif Unreferenced_In_Spec (Item) then
2499 ("?unit& is not instantiated in spec!", Name (Item));
2500 Error_Msg_N -- CODEFIX
2501 ("\?with clause can be moved to body!", Name (Item));
2510 -- Start of processing for Check_Unused_Withs
2513 if not Opt.Check_Withs
2514 or else Operating_Mode = Check_Syntax
2519 -- Flag any unused with clauses, but skip this step if we are compiling
2520 -- a subunit on its own, since we do not have enough information to
2521 -- determine whether with's are used. We will get the relevant warnings
2522 -- when we compile the parent. This is the normal style of GNAT
2523 -- compilation in any case.
2525 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2529 -- Process specified units
2531 if Spec_Unit = No_Unit then
2533 -- For main call, check all units
2535 for Unit in Main_Unit .. Last_Unit loop
2536 Check_One_Unit (Unit);
2540 -- For call for spec, check only the spec
2542 Check_One_Unit (Spec_Unit);
2544 end Check_Unused_Withs;
2546 ---------------------------------
2547 -- Generic_Package_Spec_Entity --
2548 ---------------------------------
2550 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2554 if Is_Package_Body_Entity (E) then
2560 if S = Standard_Standard then
2563 elsif Ekind (S) = E_Generic_Package then
2566 elsif Ekind (S) = E_Package then
2574 end Generic_Package_Spec_Entity;
2576 ----------------------
2577 -- Goto_Spec_Entity --
2578 ----------------------
2580 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2583 and then Present (Spec_Entity (E))
2585 return Spec_Entity (E);
2589 end Goto_Spec_Entity;
2591 --------------------------------------
2592 -- Has_Pragma_Unmodified_Check_Spec --
2593 --------------------------------------
2595 function Has_Pragma_Unmodified_Check_Spec
2596 (E : Entity_Id) return Boolean
2599 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2601 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2602 -- to mess with Unmodified flags on both body and spec entities.
2604 return Has_Unmodified (E)
2606 Has_Unmodified (Spec_Entity (E));
2609 return Has_Unmodified (E);
2611 end Has_Pragma_Unmodified_Check_Spec;
2613 ----------------------------------------
2614 -- Has_Pragma_Unreferenced_Check_Spec --
2615 ----------------------------------------
2617 function Has_Pragma_Unreferenced_Check_Spec
2618 (E : Entity_Id) return Boolean
2621 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2623 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2624 -- to mess with flags on both entities.
2626 return Has_Unreferenced (E)
2628 Has_Unreferenced (Spec_Entity (E));
2631 return Has_Unreferenced (E);
2633 end Has_Pragma_Unreferenced_Check_Spec;
2639 procedure Initialize is
2641 Warnings_Off_Pragmas.Init;
2642 Unreferenced_Entities.Init;
2643 In_Out_Warnings.Init;
2646 ------------------------------------
2647 -- Never_Set_In_Source_Check_Spec --
2648 ------------------------------------
2650 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2652 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2653 return Never_Set_In_Source (E)
2655 Never_Set_In_Source (Spec_Entity (E));
2657 return Never_Set_In_Source (E);
2659 end Never_Set_In_Source_Check_Spec;
2661 -------------------------------------
2662 -- Operand_Has_Warnings_Suppressed --
2663 -------------------------------------
2665 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2667 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2668 -- Function used to check one node to see if it is or was originally
2669 -- a reference to an entity for which Warnings are off. If so, Abandon
2670 -- is returned, otherwise OK_Orig is returned to continue the traversal
2671 -- of the original expression.
2673 function Traverse is new Traverse_Func (Check_For_Warnings);
2674 -- Function used to traverse tree looking for warnings
2676 ------------------------
2677 -- Check_For_Warnings --
2678 ------------------------
2680 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2681 R : constant Node_Id := Original_Node (N);
2684 if Nkind (R) in N_Has_Entity
2685 and then Present (Entity (R))
2686 and then Has_Warnings_Off (Entity (R))
2692 end Check_For_Warnings;
2694 -- Start of processing for Operand_Has_Warnings_Suppressed
2697 return Traverse (N) = Abandon;
2699 -- If any exception occurs, then something has gone wrong, and this is
2700 -- only a minor aesthetic issue anyway, so just say we did not find what
2701 -- we are looking for, rather than blow up.
2706 end Operand_Has_Warnings_Suppressed;
2708 -----------------------------------------
2709 -- Output_Non_Modified_In_Out_Warnings --
2710 -----------------------------------------
2712 procedure Output_Non_Modified_In_Out_Warnings is
2714 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2715 -- Given a formal parameter entity E, determines if there is a reason to
2716 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2717 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2718 -- if we have seen the address of the subprogram being taken, or if the
2719 -- subprogram is used as a generic actual (in the latter cases the
2720 -- context may force use of IN OUT, even if the parameter is not
2721 -- modifies for this particular case.
2723 -----------------------
2724 -- No_Warn_On_In_Out --
2725 -----------------------
2727 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2728 S : constant Entity_Id := Scope (E);
2729 SE : constant Entity_Id := Spec_Entity (E);
2732 -- Do not warn if address is taken, since funny business may be going
2733 -- on in treating the parameter indirectly as IN OUT.
2735 if Address_Taken (S)
2736 or else (Present (SE) and then Address_Taken (Scope (SE)))
2740 -- Do not warn if used as a generic actual, since the generic may be
2741 -- what is forcing the use of an "unnecessary" IN OUT.
2743 elsif Used_As_Generic_Actual (S)
2744 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2748 -- Else test warnings off
2750 elsif Warnings_Off_Check_Spec (S) then
2753 -- All tests for suppressing warning failed
2758 end No_Warn_On_In_Out;
2760 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2763 -- Loop through entities for which a warning may be needed
2765 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2767 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2770 -- Suppress warning in specific cases (see details in comments for
2771 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2773 if Has_Pragma_Unmodified_Check_Spec (E1)
2774 or else No_Warn_On_In_Out (E1)
2778 -- Here we generate the warning
2781 -- If -gnatwc is set then output message that we could be IN
2783 if not Is_Trivial_Subprogram (Scope (E1)) then
2784 if Warn_On_Constant then
2786 ("?formal parameter & is not modified!", E1);
2788 ("\?mode could be IN instead of `IN OUT`!", E1);
2790 -- We do not generate warnings for IN OUT parameters
2791 -- unless we have at least -gnatwu. This is deliberately
2792 -- inconsistent with the treatment of variables, but
2793 -- otherwise we get too many unexpected warnings in
2796 elsif Check_Unreferenced then
2798 ("?formal parameter& is read but "
2799 & "never assigned!", E1);
2803 -- Kill any other warnings on this entity, since this is the
2804 -- one that should dominate any other unreferenced warning.
2806 Set_Warnings_Off (E1);
2810 end Output_Non_Modified_In_Out_Warnings;
2812 ----------------------------------------
2813 -- Output_Obsolescent_Entity_Warnings --
2814 ----------------------------------------
2816 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2817 P : constant Node_Id := Parent (N);
2823 -- Do not output message if we are the scope of standard. This means
2824 -- we have a reference from a context clause from when it is originally
2825 -- processed, and that's too early to tell whether it is an obsolescent
2826 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2827 -- sure that we have a later call when the scope is available. This test
2828 -- also eliminates all messages for use clauses, which is fine (we do
2829 -- not want messages for use clauses, since they are always redundant
2830 -- with respect to the associated with clause).
2832 if S = Standard_Standard then
2836 -- Do not output message if we are in scope of an obsolescent package
2840 if Is_Obsolescent (S) then
2845 exit when S = Standard_Standard;
2848 -- Here we will output the message
2850 Error_Msg_Sloc := Sloc (E);
2852 -- Case of with clause
2854 if Nkind (P) = N_With_Clause then
2855 if Ekind (E) = E_Package then
2857 ("?with of obsolescent package& declared#", N, E);
2858 elsif Ekind (E) = E_Procedure then
2860 ("?with of obsolescent procedure& declared#", N, E);
2863 ("?with of obsolescent function& declared#", N, E);
2866 -- If we do not have a with clause, then ignore any reference to an
2867 -- obsolescent package name. We only want to give the one warning of
2868 -- withing the package, not one each time it is used to qualify.
2870 elsif Ekind (E) = E_Package then
2873 -- Procedure call statement
2875 elsif Nkind (P) = N_Procedure_Call_Statement then
2877 ("?call to obsolescent procedure& declared#", N, E);
2881 elsif Nkind (P) = N_Function_Call then
2883 ("?call to obsolescent function& declared#", N, E);
2885 -- Reference to obsolescent type
2887 elsif Is_Type (E) then
2889 ("?reference to obsolescent type& declared#", N, E);
2891 -- Reference to obsolescent component
2893 elsif Ekind_In (E, E_Component, E_Discriminant) then
2895 ("?reference to obsolescent component& declared#", N, E);
2897 -- Reference to obsolescent variable
2899 elsif Ekind (E) = E_Variable then
2901 ("?reference to obsolescent variable& declared#", N, E);
2903 -- Reference to obsolescent constant
2905 elsif Ekind (E) = E_Constant
2906 or else Ekind (E) in Named_Kind
2909 ("?reference to obsolescent constant& declared#", N, E);
2911 -- Reference to obsolescent enumeration literal
2913 elsif Ekind (E) = E_Enumeration_Literal then
2915 ("?reference to obsolescent enumeration literal& declared#", N, E);
2917 -- Generic message for any other case we missed
2921 ("?reference to obsolescent entity& declared#", N, E);
2924 -- Output additional warning if present
2926 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2927 if Obsolescent_Warnings.Table (J).Ent = E then
2928 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2929 Error_Msg_Strlen := Name_Len;
2930 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
2931 Error_Msg_N ("\\?~", N);
2935 end Output_Obsolescent_Entity_Warnings;
2937 ----------------------------------
2938 -- Output_Unreferenced_Messages --
2939 ----------------------------------
2941 procedure Output_Unreferenced_Messages is
2943 for J in Unreferenced_Entities.First ..
2944 Unreferenced_Entities.Last
2946 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
2948 end Output_Unreferenced_Messages;
2950 -----------------------------------------
2951 -- Output_Unused_Warnings_Off_Warnings --
2952 -----------------------------------------
2954 procedure Output_Unused_Warnings_Off_Warnings is
2956 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
2958 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
2959 N : Node_Id renames Wentry.N;
2960 E : Node_Id renames Wentry.E;
2963 -- Turn off Warnings_Off, or we won't get the warning!
2965 Set_Warnings_Off (E, False);
2967 -- Nothing to do if pragma was used to suppress a general warning
2969 if Warnings_Off_Used (E) then
2972 -- If pragma was used both in unmodified and unreferenced contexts
2973 -- then that's as good as the general case, no warning.
2975 elsif Warnings_Off_Used_Unmodified (E)
2977 Warnings_Off_Used_Unreferenced (E)
2981 -- Used only in context where Unmodified would have worked
2983 elsif Warnings_Off_Used_Unmodified (E) then
2985 ("?could use Unmodified instead of "
2986 & "Warnings Off for &", Pragma_Identifier (N), E);
2988 -- Used only in context where Unreferenced would have worked
2990 elsif Warnings_Off_Used_Unreferenced (E) then
2992 ("?could use Unreferenced instead of "
2993 & "Warnings Off for &", Pragma_Identifier (N), E);
2999 ("?pragma Warnings Off for & unused, "
3000 & "could be omitted", N, E);
3004 end Output_Unused_Warnings_Off_Warnings;
3006 ---------------------------
3007 -- Referenced_Check_Spec --
3008 ---------------------------
3010 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3012 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3013 return Referenced (E) or else Referenced (Spec_Entity (E));
3015 return Referenced (E);
3017 end Referenced_Check_Spec;
3019 ----------------------------------
3020 -- Referenced_As_LHS_Check_Spec --
3021 ----------------------------------
3023 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3025 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3026 return Referenced_As_LHS (E)
3027 or else Referenced_As_LHS (Spec_Entity (E));
3029 return Referenced_As_LHS (E);
3031 end Referenced_As_LHS_Check_Spec;
3033 --------------------------------------------
3034 -- Referenced_As_Out_Parameter_Check_Spec --
3035 --------------------------------------------
3037 function Referenced_As_Out_Parameter_Check_Spec
3038 (E : Entity_Id) return Boolean
3041 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3042 return Referenced_As_Out_Parameter (E)
3043 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3045 return Referenced_As_Out_Parameter (E);
3047 end Referenced_As_Out_Parameter_Check_Spec;
3049 -----------------------------
3050 -- Warn_On_Known_Condition --
3051 -----------------------------
3053 procedure Warn_On_Known_Condition (C : Node_Id) is
3055 Orig : constant Node_Id := Original_Node (C);
3056 Test_Result : Boolean;
3058 function Is_Known_Branch return Boolean;
3059 -- If the type of the condition is Boolean, the constant value of the
3060 -- condition is a boolean literal. If the type is a derived boolean
3061 -- type, the constant is wrapped in a type conversion of the derived
3062 -- literal. If the value of the condition is not a literal, no warnings
3063 -- can be produced. This function returns True if the result can be
3064 -- determined, and Test_Result is set True/False accordingly. Otherwise
3065 -- False is returned, and Test_Result is unchanged.
3067 procedure Track (N : Node_Id; Loc : Node_Id);
3068 -- Adds continuation warning(s) pointing to reason (assignment or test)
3069 -- for the operand of the conditional having a known value (or at least
3070 -- enough is known about the value to issue the warning). N is the node
3071 -- which is judged to have a known value. Loc is the warning location.
3073 ---------------------
3074 -- Is_Known_Branch --
3075 ---------------------
3077 function Is_Known_Branch return Boolean is
3079 if Etype (C) = Standard_Boolean
3080 and then Is_Entity_Name (C)
3082 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3084 Test_Result := Entity (C) = Standard_True;
3087 elsif Is_Boolean_Type (Etype (C))
3088 and then Nkind (C) = N_Unchecked_Type_Conversion
3089 and then Is_Entity_Name (Expression (C))
3090 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3093 Chars (Entity (Expression (C))) = Chars (Standard_True);
3099 end Is_Known_Branch;
3105 procedure Track (N : Node_Id; Loc : Node_Id) is
3106 Nod : constant Node_Id := Original_Node (N);
3109 if Nkind (Nod) in N_Op_Compare then
3110 Track (Left_Opnd (Nod), Loc);
3111 Track (Right_Opnd (Nod), Loc);
3113 elsif Is_Entity_Name (Nod)
3114 and then Is_Object (Entity (Nod))
3117 CV : constant Node_Id := Current_Value (Entity (Nod));
3120 if Present (CV) then
3121 Error_Msg_Sloc := Sloc (CV);
3123 if Nkind (CV) not in N_Subexpr then
3124 Error_Msg_N ("\\?(see test #)", Loc);
3126 elsif Nkind (Parent (CV)) =
3127 N_Case_Statement_Alternative
3129 Error_Msg_N ("\\?(see case alternative #)", Loc);
3132 Error_Msg_N ("\\?(see assignment #)", Loc);
3139 -- Start of processing for Warn_On_Known_Condition
3142 -- Adjust SCO condition if from source
3145 and then Comes_From_Source (Orig)
3146 and then Is_Known_Branch
3152 Atrue := Test_Result;
3154 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3158 Set_SCO_Condition (Orig, Atrue);
3162 -- Argument replacement in an inlined body can make conditions static.
3163 -- Do not emit warnings in this case.
3165 if In_Inlined_Body then
3169 if Constant_Condition_Warnings
3170 and then Is_Known_Branch
3171 and then Comes_From_Source (Original_Node (C))
3172 and then not In_Instance
3174 -- See if this is in a statement or a declaration
3178 -- If tree is not attached, do not issue warning (this is very
3179 -- peculiar, and probably arises from some other error condition)
3184 -- If we are in a declaration, then no warning, since in practice
3185 -- conditionals in declarations are used for intended tests which
3186 -- may be known at compile time, e.g. things like
3188 -- x : constant Integer := 2 + (Word'Size = 32);
3190 -- And a warning is annoying in such cases
3192 elsif Nkind (P) in N_Declaration
3194 Nkind (P) in N_Later_Decl_Item
3198 -- Don't warn in assert or check pragma, since presumably tests in
3199 -- such a context are very definitely intended, and might well be
3200 -- known at compile time. Note that we have to test the original
3201 -- node, since assert pragmas get rewritten at analysis time.
3203 elsif Nkind (Original_Node (P)) = N_Pragma
3204 and then (Pragma_Name (Original_Node (P)) = Name_Assert
3206 Pragma_Name (Original_Node (P)) = Name_Check)
3211 exit when Is_Statement (P);
3215 -- Here we issue the warning unless some sub-operand has warnings
3216 -- set off, in which case we suppress the warning for the node. If
3217 -- the original expression is an inequality, it has been expanded
3218 -- into a negation, and the value of the original expression is the
3219 -- negation of the equality. If the expression is an entity that
3220 -- appears within a negation, it is clearer to flag the negation
3221 -- itself, and report on its constant value.
3223 if not Operand_Has_Warnings_Suppressed (C) then
3225 True_Branch : Boolean := Test_Result;
3226 Cond : Node_Id := C;
3229 if Present (Parent (C))
3230 and then Nkind (Parent (C)) = N_Op_Not
3232 True_Branch := not True_Branch;
3237 if Is_Entity_Name (Original_Node (C))
3238 and then Nkind (Cond) /= N_Op_Not
3241 ("object & is always True?", Cond, Original_Node (C));
3242 Track (Original_Node (C), Cond);
3245 Error_Msg_N ("condition is always True?", Cond);
3250 Error_Msg_N ("condition is always False?", Cond);
3256 end Warn_On_Known_Condition;
3258 ---------------------------------------
3259 -- Warn_On_Modified_As_Out_Parameter --
3260 ---------------------------------------
3262 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3265 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3266 or else Warn_On_All_Unread_Out_Parameters;
3267 end Warn_On_Modified_As_Out_Parameter;
3269 ---------------------------------
3270 -- Warn_On_Overlapping_Actuals --
3271 ---------------------------------
3273 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3274 Act1, Act2 : Node_Id;
3275 Form1, Form2 : Entity_Id;
3278 if not Warn_On_Overlap then
3282 -- Exclude calls rewritten as enumeration literals
3284 if Nkind (N) not in N_Subprogram_Call then
3288 -- Exclude calls to library subprograms. Container operations specify
3289 -- safe behavior when source and target coincide.
3291 if Is_Predefined_File_Name
3292 (Unit_File_Name (Get_Source_Unit (Sloc (Subp))))
3297 Form1 := First_Formal (Subp);
3298 Act1 := First_Actual (N);
3299 while Present (Form1) and then Present (Act1) loop
3300 if Ekind (Form1) /= E_In_Parameter then
3301 Form2 := First_Formal (Subp);
3302 Act2 := First_Actual (N);
3303 while Present (Form2) and then Present (Act2) loop
3305 and then Ekind (Form2) /= E_Out_Parameter
3307 (Denotes_Same_Object (Act1, Act2)
3309 Denotes_Same_Prefix (Act1, Act2))
3311 -- Exclude generic types and guard against previous errors.
3314 or else No (Etype (Act1))
3315 or else No (Etype (Act2))
3319 elsif Is_Generic_Type (Etype (Act1))
3321 Is_Generic_Type (Etype (Act2))
3325 -- If the actual is a function call in prefix notation,
3326 -- there is no real overlap.
3328 elsif Nkind (Act2) = N_Function_Call then
3331 -- If type is not by-copy we can assume that the aliasing is
3335 Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3345 -- Find matching actual
3347 Act := First_Actual (N);
3348 Form := First_Formal (Subp);
3349 while Act /= Act2 loop
3354 if Is_Elementary_Type (Etype (Act1))
3355 and then Ekind (Form2) = E_In_Parameter
3357 null; -- No real aliasing
3359 elsif Is_Elementary_Type (Etype (Act2))
3360 and then Ekind (Form2) = E_In_Parameter
3364 -- If the call was written in prefix notation, and
3365 -- thus its prefix before rewriting was a selected
3366 -- component, count only visible actuals in the call.
3368 elsif Is_Entity_Name (First_Actual (N))
3369 and then Nkind (Original_Node (N)) = Nkind (N)
3370 and then Nkind (Name (Original_Node (N))) =
3371 N_Selected_Component
3373 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3375 Entity (Prefix (Name (Original_Node (N)))) =
3376 Entity (First_Actual (N))
3378 if Act1 = First_Actual (N) then
3380 ("`IN OUT` prefix overlaps with actual for&?",
3384 -- For greater clarity, give name of formal.
3386 Error_Msg_Node_2 := Form;
3388 ("writable actual for & overlaps with"
3389 & " actual for&?", Act1, Form);
3393 Error_Msg_Node_2 := Form;
3395 ("writable actual for & overlaps with"
3396 & " actual for&?", Act1, Form1);
3404 Next_Formal (Form2);
3409 Next_Formal (Form1);
3412 end Warn_On_Overlapping_Actuals;
3414 ------------------------------
3415 -- Warn_On_Suspicious_Index --
3416 ------------------------------
3418 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3421 -- Set to lower bound for a suspicious type
3424 -- Entity for array reference
3429 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3430 -- Tests to see if Typ is a type for which we may have a suspicious
3431 -- index, namely an unconstrained array type, whose lower bound is
3432 -- either zero or one. If so, True is returned, and Low_Bound is set
3433 -- to this lower bound. If not, False is returned, and Low_Bound is
3434 -- undefined on return.
3436 -- For now, we limit this to standard string types, so any other
3437 -- unconstrained types return False. We may change our minds on this
3438 -- later on, but strings seem the most important case.
3440 procedure Test_Suspicious_Index;
3441 -- Test if index is of suspicious type and if so, generate warning
3443 ------------------------
3444 -- Is_Suspicious_Type --
3445 ------------------------
3447 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3451 if Is_Array_Type (Typ)
3452 and then not Is_Constrained (Typ)
3453 and then Number_Dimensions (Typ) = 1
3454 and then (Root_Type (Typ) = Standard_String
3456 Root_Type (Typ) = Standard_Wide_String
3458 Root_Type (Typ) = Standard_Wide_Wide_String)
3459 and then not Has_Warnings_Off (Typ)
3461 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3463 if Compile_Time_Known_Value (LB) then
3464 Low_Bound := Expr_Value (LB);
3465 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3470 end Is_Suspicious_Type;
3472 ---------------------------
3473 -- Test_Suspicious_Index --
3474 ---------------------------
3476 procedure Test_Suspicious_Index is
3478 function Length_Reference (N : Node_Id) return Boolean;
3479 -- Check if node N is of the form Name'Length
3482 -- Generate first warning line
3484 ----------------------
3485 -- Length_Reference --
3486 ----------------------
3488 function Length_Reference (N : Node_Id) return Boolean is
3489 R : constant Node_Id := Original_Node (N);
3492 Nkind (R) = N_Attribute_Reference
3493 and then Attribute_Name (R) = Name_Length
3494 and then Is_Entity_Name (Prefix (R))
3495 and then Entity (Prefix (R)) = Ent;
3496 end Length_Reference;
3504 Error_Msg_Uint_1 := Low_Bound;
3505 Error_Msg_FE -- CODEFIX
3506 ("?index for& may assume lower bound of^", X, Ent);
3509 -- Start of processing for Test_Suspicious_Index
3512 -- Nothing to do if subscript does not come from source (we don't
3513 -- want to give garbage warnings on compiler expanded code, e.g. the
3514 -- loops generated for slice assignments. Such junk warnings would
3515 -- be placed on source constructs with no subscript in sight!)
3517 if not Comes_From_Source (Original_Node (X)) then
3521 -- Case where subscript is a constant integer
3523 if Nkind (X) = N_Integer_Literal then
3526 -- Case where original form of subscript is an integer literal
3528 if Nkind (Original_Node (X)) = N_Integer_Literal then
3529 if Intval (X) = Low_Bound then
3530 Error_Msg_FE -- CODEFIX
3531 ("\suggested replacement: `&''First`", X, Ent);
3533 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3534 Error_Msg_FE -- CODEFIX
3535 ("\suggested replacement: `&''First + ^`", X, Ent);
3539 -- Case where original form of subscript is more complex
3542 -- Build string X'First - 1 + expression where the expression
3543 -- is the original subscript. If the expression starts with "1
3544 -- + ", then the "- 1 + 1" is elided.
3546 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3547 Error_Msg_Strlen := 13;
3550 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3551 Tref : constant Source_Buffer_Ptr :=
3552 Source_Text (Get_Source_File_Index (Sref));
3553 -- Tref (Sref) is used to scan the subscript
3556 -- Parentheses counter when scanning subscript
3559 -- Tref (Sref) points to start of subscript
3561 -- Elide - 1 if subscript starts with 1 +
3563 if Tref (Sref .. Sref + 2) = "1 +" then
3564 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3567 elsif Tref (Sref .. Sref + 1) = "1+" then
3568 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3572 -- Now we will copy the subscript to the string buffer
3576 -- Count parens, exit if terminating right paren. Note
3577 -- check to ignore paren appearing as character literal.
3579 if Tref (Sref + 1) = '''
3581 Tref (Sref - 1) = '''
3585 if Tref (Sref) = '(' then
3587 elsif Tref (Sref) = ')' then
3593 -- Done if terminating double dot (slice case)
3596 and then (Tref (Sref .. Sref + 1) = ".."
3598 Tref (Sref .. Sref + 2) = " ..");
3600 -- Quit if we have hit EOF character, something wrong
3602 if Tref (Sref) = EOF then
3606 -- String literals are too much of a pain to handle
3608 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3612 -- If we have a 'Range reference, then this is a case
3613 -- where we cannot easily give a replacement. Don't try!
3615 if Tref (Sref .. Sref + 4) = "range"
3616 and then Tref (Sref - 1) < 'A'
3617 and then Tref (Sref + 5) < 'A'
3622 -- Else store next character
3624 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3625 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3628 -- If we get more than 40 characters then the expression
3629 -- is too long to copy, or something has gone wrong. In
3630 -- either case, just skip the attempt at a suggested fix.
3632 if Error_Msg_Strlen > 40 then
3638 -- Replacement subscript is now in string buffer
3640 Error_Msg_FE -- CODEFIX
3641 ("\suggested replacement: `&~`", Original_Node (X), Ent);
3644 -- Case where subscript is of the form X'Length
3646 elsif Length_Reference (X) then
3648 Error_Msg_Node_2 := Ent;
3650 ("\suggest replacement of `&''Length` by `&''Last`",
3653 -- Case where subscript is of the form X'Length - expression
3655 elsif Nkind (X) = N_Op_Subtract
3656 and then Length_Reference (Left_Opnd (X))
3659 Error_Msg_Node_2 := Ent;
3661 ("\suggest replacement of `&''Length` by `&''Last`",
3662 Left_Opnd (X), Ent);
3664 end Test_Suspicious_Index;
3666 -- Start of processing for Warn_On_Suspicious_Index
3669 -- Only process if warnings activated
3671 if Warn_On_Assumed_Low_Bound then
3673 -- Test if array is simple entity name
3675 if Is_Entity_Name (Name) then
3677 -- Test if array is parameter of unconstrained string type
3679 Ent := Entity (Name);
3683 and then Is_Suspicious_Type (Typ)
3684 and then not Low_Bound_Tested (Ent)
3686 Test_Suspicious_Index;
3690 end Warn_On_Suspicious_Index;
3692 --------------------------------------
3693 -- Warn_On_Unassigned_Out_Parameter --
3694 --------------------------------------
3696 procedure Warn_On_Unassigned_Out_Parameter
3697 (Return_Node : Node_Id;
3698 Scope_Id : Entity_Id)
3704 -- Ignore if procedure or return statement does not come from source
3706 if not Comes_From_Source (Scope_Id)
3707 or else not Comes_From_Source (Return_Node)
3712 -- Loop through formals
3714 Form := First_Formal (Scope_Id);
3715 while Present (Form) loop
3717 -- We are only interested in OUT parameters that come from source
3718 -- and are never set in the source, and furthermore only in scalars
3719 -- since non-scalars generate too many false positives.
3721 if Ekind (Form) = E_Out_Parameter
3722 and then Never_Set_In_Source_Check_Spec (Form)
3723 and then Is_Scalar_Type (Etype (Form))
3724 and then not Present (Unset_Reference (Form))
3726 -- Before we issue the warning, an add ad hoc defence against the
3727 -- most common case of false positives with this warning which is
3728 -- the case where there is a Boolean OUT parameter that has been
3729 -- set, and whose meaning is "ignore the values of the other
3730 -- parameters". We can't of course reliably tell this case at
3731 -- compile time, but the following test kills a lot of false
3732 -- positives, without generating a significant number of false
3733 -- negatives (missed real warnings).
3735 Form2 := First_Formal (Scope_Id);
3736 while Present (Form2) loop
3737 if Ekind (Form2) = E_Out_Parameter
3738 and then Root_Type (Etype (Form2)) = Standard_Boolean
3739 and then not Never_Set_In_Source_Check_Spec (Form2)
3744 Next_Formal (Form2);
3747 -- Here all conditions are met, record possible unset reference
3749 Set_Unset_Reference (Form, Return_Node);
3754 end Warn_On_Unassigned_Out_Parameter;
3756 ---------------------------------
3757 -- Warn_On_Unreferenced_Entity --
3758 ---------------------------------
3760 procedure Warn_On_Unreferenced_Entity
3761 (Spec_E : Entity_Id;
3762 Body_E : Entity_Id := Empty)
3764 E : Entity_Id := Spec_E;
3767 if not Referenced_Check_Spec (E)
3768 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3769 and then not Warnings_Off_Check_Spec (E)
3774 -- Case of variable that is assigned but not read. We suppress
3775 -- the message if the variable is volatile, has an address
3776 -- clause, is aliased, or is a renaming, or is imported.
3778 if Referenced_As_LHS_Check_Spec (E)
3779 and then No (Address_Clause (E))
3780 and then not Is_Volatile (E)
3782 if Warn_On_Modified_Unread
3783 and then not Is_Imported (E)
3784 and then not Is_Aliased (E)
3785 and then No (Renamed_Object (E))
3787 if not Has_Pragma_Unmodified_Check_Spec (E) then
3788 Error_Msg_N -- CODEFIX
3789 ("?variable & is assigned but never read!", E);
3792 Set_Last_Assignment (E, Empty);
3795 -- Normal case of neither assigned nor read (exclude variables
3796 -- referenced as out parameters, since we already generated
3797 -- appropriate warnings at the call point in this case).
3799 elsif not Referenced_As_Out_Parameter (E) then
3801 -- We suppress the message for types for which a valid
3802 -- pragma Unreferenced_Objects has been given, otherwise
3803 -- we go ahead and give the message.
3805 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3807 -- Distinguish renamed case in message
3809 if Present (Renamed_Object (E))
3810 and then Comes_From_Source (Renamed_Object (E))
3812 Error_Msg_N -- CODEFIX
3813 ("?renamed variable & is not referenced!", E);
3815 Error_Msg_N -- CODEFIX
3816 ("?variable & is not referenced!", E);
3822 if Present (Renamed_Object (E))
3823 and then Comes_From_Source (Renamed_Object (E))
3825 Error_Msg_N -- CODEFIX
3826 ("?renamed constant & is not referenced!", E);
3828 Error_Msg_N -- CODEFIX
3829 ("?constant & is not referenced!", E);
3832 when E_In_Parameter |
3833 E_In_Out_Parameter =>
3835 -- Do not emit message for formals of a renaming, because
3836 -- they are never referenced explicitly.
3838 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E))))
3839 /= N_Subprogram_Renaming_Declaration
3841 -- Suppress this message for an IN OUT parameter of a
3842 -- non-scalar type, since it is normal to have only an
3843 -- assignment in such a case.
3845 if Ekind (E) = E_In_Parameter
3846 or else not Referenced_As_LHS_Check_Spec (E)
3847 or else Is_Scalar_Type (Etype (E))
3849 if Present (Body_E) then
3853 if not Is_Trivial_Subprogram (Scope (E)) then
3854 Error_Msg_NE -- CODEFIX
3855 ("?formal parameter & is not referenced!",
3861 when E_Out_Parameter =>
3864 when E_Discriminant =>
3865 Error_Msg_N ("?discriminant & is not referenced!", E);
3867 when E_Named_Integer |
3869 Error_Msg_N -- CODEFIX
3870 ("?named number & is not referenced!", E);
3872 when Formal_Object_Kind =>
3873 Error_Msg_N -- CODEFIX
3874 ("?formal object & is not referenced!", E);
3876 when E_Enumeration_Literal =>
3877 Error_Msg_N -- CODEFIX
3878 ("?literal & is not referenced!", E);
3881 Error_Msg_N -- CODEFIX
3882 ("?function & is not referenced!", E);
3885 Error_Msg_N -- CODEFIX
3886 ("?procedure & is not referenced!", E);
3889 Error_Msg_N -- CODEFIX
3890 ("?package & is not referenced!", E);
3893 Error_Msg_N -- CODEFIX
3894 ("?exception & is not referenced!", E);
3897 Error_Msg_N -- CODEFIX
3898 ("?label & is not referenced!", E);
3900 when E_Generic_Procedure =>
3901 Error_Msg_N -- CODEFIX
3902 ("?generic procedure & is never instantiated!", E);
3904 when E_Generic_Function =>
3905 Error_Msg_N -- CODEFIX
3906 ("?generic function & is never instantiated!", E);
3909 Error_Msg_N -- CODEFIX
3910 ("?type & is not referenced!", E);
3913 Error_Msg_N -- CODEFIX
3914 ("?& is not referenced!", E);
3917 -- Kill warnings on the entity on which the message has been posted
3919 Set_Warnings_Off (E);
3921 end Warn_On_Unreferenced_Entity;
3923 --------------------------------
3924 -- Warn_On_Useless_Assignment --
3925 --------------------------------
3927 procedure Warn_On_Useless_Assignment
3929 N : Node_Id := Empty)
3934 function Check_Ref (N : Node_Id) return Traverse_Result;
3935 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
3936 -- the entity in question is found.
3938 function Test_No_Refs is new Traverse_Func (Check_Ref);
3944 function Check_Ref (N : Node_Id) return Traverse_Result is
3946 -- Check reference to our identifier. We use name equality here
3947 -- because the exception handlers have not yet been analyzed. This
3948 -- is not quite right, but it really does not matter that we fail
3949 -- to output the warning in some obscure cases of name clashes.
3951 if Nkind (N) = N_Identifier
3952 and then Chars (N) = Chars (Ent)
3960 -- Start of processing for Warn_On_Useless_Assignment
3963 -- Check if this is a case we want to warn on, a scalar or access
3964 -- variable with the last assignment field set, with warnings enabled,
3965 -- and which is not imported or exported. We also check that it is OK
3966 -- to capture the value. We are not going to capture any value, but
3967 -- the warning message depends on the same kind of conditions.
3969 if Is_Assignable (Ent)
3970 and then not Is_Return_Object (Ent)
3971 and then Present (Last_Assignment (Ent))
3972 and then not Is_Imported (Ent)
3973 and then not Is_Exported (Ent)
3974 and then Safe_To_Capture_Value (N, Ent)
3975 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
3977 -- Before we issue the message, check covering exception handlers.
3978 -- Search up tree for enclosing statement sequences and handlers.
3980 P := Parent (Last_Assignment (Ent));
3981 while Present (P) loop
3983 -- Something is really wrong if we don't find a handled statement
3984 -- sequence, so just suppress the warning.
3987 Set_Last_Assignment (Ent, Empty);
3990 -- When we hit a package/subprogram body, issue warning and exit
3992 elsif Nkind (P) = N_Subprogram_Body
3993 or else Nkind (P) = N_Package_Body
3995 -- Case of assigned value never referenced
3999 LA : constant Node_Id := Last_Assignment (Ent);
4002 -- Don't give this for OUT and IN OUT formals, since
4003 -- clearly caller may reference the assigned value. Also
4004 -- never give such warnings for internal variables.
4006 if Ekind (Ent) = E_Variable
4007 and then not Is_Internal_Name (Chars (Ent))
4009 -- Give appropriate message, distinguishing between
4010 -- assignment statements and out parameters.
4012 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4013 N_Parameter_Association)
4016 ("?& modified by call, but value never "
4017 & "referenced", LA, Ent);
4020 Error_Msg_NE -- CODEFIX
4021 ("?useless assignment to&, value never "
4022 & "referenced!", LA, Ent);
4027 -- Case of assigned value overwritten
4031 LA : constant Node_Id := Last_Assignment (Ent);
4034 Error_Msg_Sloc := Sloc (N);
4036 -- Give appropriate message, distinguishing between
4037 -- assignment statements and out parameters.
4039 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4040 N_Parameter_Association)
4043 ("?& modified by call, but value overwritten #!",
4046 Error_Msg_NE -- CODEFIX
4047 ("?useless assignment to&, value overwritten #!",
4053 -- Clear last assignment indication and we are done
4055 Set_Last_Assignment (Ent, Empty);
4058 -- Enclosing handled sequence of statements
4060 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4062 -- Check exception handlers present
4064 if Present (Exception_Handlers (P)) then
4066 -- If we are not at the top level, we regard an inner
4067 -- exception handler as a decisive indicator that we should
4068 -- not generate the warning, since the variable in question
4069 -- may be accessed after an exception in the outer block.
4071 if Nkind (Parent (P)) /= N_Subprogram_Body
4072 and then Nkind (Parent (P)) /= N_Package_Body
4074 Set_Last_Assignment (Ent, Empty);
4077 -- Otherwise we are at the outer level. An exception
4078 -- handler is significant only if it references the
4079 -- variable in question, or if the entity in question
4080 -- is an OUT or IN OUT parameter, which which case
4081 -- the caller can reference it after the exception
4082 -- handler completes.
4085 if Is_Formal (Ent) then
4086 Set_Last_Assignment (Ent, Empty);
4090 X := First (Exception_Handlers (P));
4091 while Present (X) loop
4092 if Test_No_Refs (X) = Abandon then
4093 Set_Last_Assignment (Ent, Empty);
4107 end Warn_On_Useless_Assignment;
4109 ---------------------------------
4110 -- Warn_On_Useless_Assignments --
4111 ---------------------------------
4113 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4116 if Warn_On_Modified_Unread
4117 and then In_Extended_Main_Source_Unit (E)
4119 Ent := First_Entity (E);
4120 while Present (Ent) loop
4121 Warn_On_Useless_Assignment (Ent);
4125 end Warn_On_Useless_Assignments;
4127 -----------------------------
4128 -- Warnings_Off_Check_Spec --
4129 -----------------------------
4131 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4133 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4135 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4136 -- to mess with flags on both entities.
4138 return Has_Warnings_Off (E)
4140 Has_Warnings_Off (Spec_Entity (E));
4143 return Has_Warnings_Off (E);
4145 end Warnings_Off_Check_Spec;