1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2017, 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;
32 with Lib.Xref; use Lib.Xref;
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_Prag; use Sem_Prag;
43 with Sem_Util; use Sem_Util;
44 with Sinfo; use Sinfo;
45 with Sinput; use Sinput;
46 with Snames; use Snames;
47 with Stand; use Stand;
48 with Stringt; use Stringt;
49 with Tbuild; use Tbuild;
50 with Uintp; use Uintp;
52 package body Sem_Warn is
54 -- The following table collects Id's of entities that are potentially
55 -- unreferenced. See Check_Unset_Reference for further details.
56 -- ??? Check_Unset_Reference has zero information about this table.
58 package Unreferenced_Entities is new Table.Table (
59 Table_Component_Type => Entity_Id,
60 Table_Index_Type => Nat,
62 Table_Initial => Alloc.Unreferenced_Entities_Initial,
63 Table_Increment => Alloc.Unreferenced_Entities_Increment,
64 Table_Name => "Unreferenced_Entities");
66 -- The following table collects potential warnings for IN OUT parameters
67 -- that are referenced but not modified. These warnings are processed when
68 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
69 -- The reason that we defer output of these messages is that we want to
70 -- detect the case where the relevant procedure is used as a generic actual
71 -- in an instantiation, since we suppress the warnings in this case. The
72 -- flag Used_As_Generic_Actual will be set in this case, but only at the
73 -- point of usage. Similarly, we suppress the message if the address of the
74 -- procedure is taken, where the flag Address_Taken may be set later.
76 package In_Out_Warnings is new Table.Table (
77 Table_Component_Type => Entity_Id,
78 Table_Index_Type => Nat,
80 Table_Initial => Alloc.In_Out_Warnings_Initial,
81 Table_Increment => Alloc.In_Out_Warnings_Increment,
82 Table_Name => "In_Out_Warnings");
84 --------------------------------------------------------
85 -- Handling of Warnings Off, Unmodified, Unreferenced --
86 --------------------------------------------------------
88 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
89 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
90 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
92 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
93 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
94 -- must follow some important rules.
96 -- Call these functions as late as possible, after completing all other
97 -- tests, just before the warnings is given. For example, don't write:
99 -- if not Has_Warnings_Off (E)
100 -- and then some-other-predicate-on-E then ..
102 -- Instead the following is preferred
104 -- if some-other-predicate-on-E
105 -- and then Has_Warnings_Off (E)
107 -- This way if some-other-predicate is false, we avoid a false indication
108 -- that a Warnings (Off, E) pragma was useful in preventing a warning.
110 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
111 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
112 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
113 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
114 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
115 -- and so a subsequent test is not needed anyway (though it is harmless).
117 -----------------------
118 -- Local Subprograms --
119 -----------------------
121 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean;
122 -- This returns true if the entity E is declared within a generic package.
123 -- The point of this is to detect variables which are not assigned within
124 -- the generic, but might be assigned outside the package for any given
125 -- instance. These are cases where we leave the warnings to be posted for
126 -- the instance, when we will know more.
128 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id;
129 -- If E is a parameter entity for a subprogram body, then this function
130 -- returns the corresponding spec entity, if not, E is returned unchanged.
132 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean;
133 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
134 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
135 -- a body formal, the setting of the flag in the corresponding spec is
136 -- also checked (and True returned if either flag is True).
138 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean;
139 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
140 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
141 -- a body formal, the setting of the flag in the corresponding spec is
142 -- also checked (and True returned if either flag is True).
144 function Is_Attribute_And_Known_Value_Comparison
145 (Op : Node_Id) return Boolean;
146 -- Determine whether operator Op denotes a comparison where the left
147 -- operand is an attribute reference and the value of the right operand is
148 -- known at compile time.
150 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean;
151 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
152 -- this is simply the setting of the flag Never_Set_In_Source. If E is
153 -- a body formal, the setting of the flag in the corresponding spec is
154 -- also checked (and False returned if either flag is False).
156 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
157 -- This function traverses the expression tree represented by the node N
158 -- and determines if any sub-operand is a reference to an entity for which
159 -- the Warnings_Off flag is set. True is returned if such an entity is
160 -- encountered, and False otherwise.
162 function Referenced_Check_Spec (E : Entity_Id) return Boolean;
163 -- Tests Referenced status for entity E. If E is not a formal, this is
164 -- simply the setting of the flag Referenced. If E is a body formal, the
165 -- setting of the flag in the corresponding spec is also checked (and True
166 -- returned if either flag is True).
168 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean;
169 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
170 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
171 -- formal, the setting of the flag in the corresponding spec is also
172 -- checked (and True returned if either flag is True).
174 function Referenced_As_Out_Parameter_Check_Spec
175 (E : Entity_Id) return Boolean;
176 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
177 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
178 -- is a body formal, the setting of the flag in the corresponding spec is
179 -- also checked (and True returned if either flag is True).
181 procedure Warn_On_Unreferenced_Entity
183 Body_E : Entity_Id := Empty);
184 -- Output warnings for unreferenced entity E. For the case of an entry
185 -- formal, Body_E is the corresponding body entity for a particular
186 -- accept statement, and the message is posted on Body_E. In all other
187 -- cases, Body_E is ignored and must be Empty.
189 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean;
190 -- Returns True if Warnings_Off is set for the entity E or (in the case
191 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
193 --------------------------
194 -- Check_Code_Statement --
195 --------------------------
197 procedure Check_Code_Statement (N : Node_Id) is
199 -- If volatile, nothing to worry about
201 if Is_Asm_Volatile (N) then
205 -- Warn if no input or no output
207 Setup_Asm_Inputs (N);
209 if No (Asm_Input_Value) then
211 ("??code statement with no inputs should usually be Volatile!", N);
215 Setup_Asm_Outputs (N);
217 if No (Asm_Output_Variable) then
219 ("??code statement with no outputs should usually be Volatile!", N);
222 end Check_Code_Statement;
224 ---------------------------------
225 -- Check_Infinite_Loop_Warning --
226 ---------------------------------
228 -- The case we look for is a while loop which tests a local variable, where
229 -- there is no obvious direct or possible indirect update of the variable
230 -- within the body of the loop.
232 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
233 Expression : Node_Id := Empty;
234 -- Set to WHILE or EXIT WHEN condition to be tested
236 Ref : Node_Id := Empty;
237 -- Reference in Expression to variable that might not be modified
238 -- in loop, indicating a possible infinite loop.
240 Var : Entity_Id := Empty;
241 -- Corresponding entity (entity of Ref)
243 Function_Call_Found : Boolean := False;
244 -- True if Find_Var found a function call in the condition
246 procedure Find_Var (N : Node_Id);
247 -- Inspect condition to see if it depends on a single entity reference.
248 -- If so, Ref is set to point to the reference node, and Var is set to
249 -- the referenced Entity.
251 function Has_Condition_Actions (Iter : Node_Id) return Boolean;
252 -- Determine whether iteration scheme Iter has meaningful condition
255 function Has_Indirection (T : Entity_Id) return Boolean;
256 -- If the controlling variable is an access type, or is a record type
257 -- with access components, assume that it is changed indirectly and
258 -- suppress the warning. As a concession to low-level programming, in
259 -- particular within Declib, we also suppress warnings on a record
260 -- type that contains components of type Address or Short_Address.
262 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
263 -- Given an entity name, see if the name appears to have something to
264 -- do with I/O or network stuff, and if so, return True. Used to kill
265 -- some false positives on a heuristic basis that such functions will
266 -- likely have some strange side effect dependencies. A rather strange
267 -- test, but warning messages are in the heuristics business.
269 function Test_Ref (N : Node_Id) return Traverse_Result;
270 -- Test for reference to variable in question. Returns Abandon if
271 -- matching reference found. Used in instantiation of No_Ref_Found.
273 function No_Ref_Found is new Traverse_Func (Test_Ref);
274 -- Function to traverse body of procedure. Returns Abandon if matching
281 procedure Find_Var (N : Node_Id) is
283 -- Condition is a direct variable reference
285 if Is_Entity_Name (N) then
289 -- Case of condition is a comparison with compile time known value
291 elsif Nkind (N) in N_Op_Compare then
292 if Compile_Time_Known_Value (Right_Opnd (N)) then
293 Find_Var (Left_Opnd (N));
295 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
296 Find_Var (Right_Opnd (N));
298 -- Ignore any other comparison
304 -- If condition is a negation, check its operand
306 elsif Nkind (N) = N_Op_Not then
307 Find_Var (Right_Opnd (N));
309 -- Case of condition is function call
311 elsif Nkind (N) = N_Function_Call then
313 Function_Call_Found := True;
315 -- Forget it if function name is not entity, who knows what
316 -- we might be calling?
318 if not Is_Entity_Name (Name (N)) then
321 -- Forget it if function name is suspicious. A strange test
322 -- but warning generation is in the heuristics business.
324 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
327 -- Forget it if function is marked Volatile_Function
329 elsif Is_Volatile_Function (Entity (Name (N))) then
332 -- Forget it if warnings are suppressed on function entity
334 elsif Has_Warnings_Off (Entity (Name (N))) then
338 -- OK, see if we have one argument
341 PA : constant List_Id := Parameter_Associations (N);
344 -- One argument, so check the argument
346 if Present (PA) and then List_Length (PA) = 1 then
347 if Nkind (First (PA)) = N_Parameter_Association then
348 Find_Var (Explicit_Actual_Parameter (First (PA)));
350 Find_Var (First (PA));
360 -- Any other kind of node is not something we warn for
367 ---------------------------
368 -- Has_Condition_Actions --
369 ---------------------------
371 function Has_Condition_Actions (Iter : Node_Id) return Boolean is
375 -- A call marker is not considered a meaningful action because it
376 -- acts as an annotation and has no runtime semantics.
378 Action := First (Condition_Actions (Iter));
379 while Present (Action) loop
380 if Nkind (Action) /= N_Call_Marker then
388 end Has_Condition_Actions;
390 ---------------------
391 -- Has_Indirection --
392 ---------------------
394 function Has_Indirection (T : Entity_Id) return Boolean is
399 if Is_Access_Type (T) then
402 elsif Is_Private_Type (T)
403 and then Present (Full_View (T))
404 and then Is_Access_Type (Full_View (T))
408 elsif Is_Record_Type (T) then
411 elsif Is_Private_Type (T)
412 and then Present (Full_View (T))
413 and then Is_Record_Type (Full_View (T))
415 Rec := Full_View (T);
420 Comp := First_Component (Rec);
421 while Present (Comp) loop
422 if Is_Access_Type (Etype (Comp))
423 or else Is_Descendant_Of_Address (Etype (Comp))
428 Next_Component (Comp);
434 ---------------------------------
435 -- Is_Suspicious_Function_Name --
436 ---------------------------------
438 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
441 function Substring_Present (S : String) return Boolean;
442 -- Returns True if name buffer has given string delimited by non-
443 -- alphabetic characters or by end of string. S is lower case.
445 -----------------------
446 -- Substring_Present --
447 -----------------------
449 function Substring_Present (S : String) return Boolean is
450 Len : constant Natural := S'Length;
453 for J in 1 .. Name_Len - (Len - 1) loop
454 if Name_Buffer (J .. J + (Len - 1)) = S
455 and then (J = 1 or else Name_Buffer (J - 1) not in 'a' .. 'z')
458 or else Name_Buffer (J + Len) not in 'a' .. 'z')
465 end Substring_Present;
467 -- Start of processing for Is_Suspicious_Function_Name
471 while Present (S) and then S /= Standard_Standard loop
472 Get_Name_String (Chars (S));
474 if Substring_Present ("io")
475 or else Substring_Present ("file")
476 or else Substring_Present ("network")
485 end Is_Suspicious_Function_Name;
491 function Test_Ref (N : Node_Id) return Traverse_Result is
493 -- Waste of time to look at the expression we are testing
495 if N = Expression then
498 -- Direct reference to variable in question
500 elsif Is_Entity_Name (N)
501 and then Present (Entity (N))
502 and then Entity (N) = Var
504 -- If this is an lvalue, then definitely abandon, since
505 -- this could be a direct modification of the variable.
507 if May_Be_Lvalue (N) then
511 -- If the condition contains a function call, we consider it may
512 -- be modified by side effects from a procedure call. Otherwise,
513 -- we consider the condition may not be modified, although that
514 -- might happen if Variable is itself a by-reference parameter,
515 -- and the procedure called modifies the global object referred to
516 -- by Variable, but we actually prefer to issue a warning in this
517 -- odd case. Note that the case where the procedure called has
518 -- visibility over Variable is treated in another case below.
520 if Function_Call_Found then
528 exit when P = Loop_Statement;
530 -- Abandon if at procedure call, or something strange is
531 -- going on (perhaps a node with no parent that should
532 -- have one but does not?) As always, for a warning we
533 -- prefer to just abandon the warning than get into the
534 -- business of complaining about the tree structure here.
537 or else Nkind (P) = N_Procedure_Call_Statement
545 -- Reference to variable renaming variable in question
547 elsif Is_Entity_Name (N)
548 and then Present (Entity (N))
549 and then Ekind (Entity (N)) = E_Variable
550 and then Present (Renamed_Object (Entity (N)))
551 and then Is_Entity_Name (Renamed_Object (Entity (N)))
552 and then Entity (Renamed_Object (Entity (N))) = Var
553 and then May_Be_Lvalue (N)
557 -- Call to subprogram
559 elsif Nkind (N) in N_Subprogram_Call then
561 -- If subprogram is within the scope of the entity we are dealing
562 -- with as the loop variable, then it could modify this parameter,
563 -- so we abandon in this case. In the case of a subprogram that is
564 -- not an entity we also abandon. The check for no entity being
565 -- present is a defense against previous errors.
567 if not Is_Entity_Name (Name (N))
568 or else No (Entity (Name (N)))
569 or else Scope_Within (Entity (Name (N)), Scope (Var))
574 -- If any of the arguments are of type access to subprogram, then
575 -- we may have funny side effects, so no warning in this case.
580 Actual := First_Actual (N);
581 while Present (Actual) loop
582 if Is_Access_Subprogram_Type (Etype (Actual)) then
585 Next_Actual (Actual);
590 -- Declaration of the variable in question
592 elsif Nkind (N) = N_Object_Declaration
593 and then Defining_Identifier (N) = Var
598 -- All OK, continue scan
603 -- Start of processing for Check_Infinite_Loop_Warning
606 -- Skip processing if debug flag gnatd.w is set
608 if Debug_Flag_Dot_W then
612 -- Deal with Iteration scheme present
615 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
618 if Present (Iter) then
622 if Present (Condition (Iter)) then
624 -- Skip processing for while iteration with conditions actions,
625 -- since they make it too complicated to get the warning right.
627 if Has_Condition_Actions (Iter) then
631 -- Capture WHILE condition
633 Expression := Condition (Iter);
635 -- For iteration, do not process, since loop will always terminate
637 elsif Present (Loop_Parameter_Specification (Iter)) then
643 -- Check chain of EXIT statements, we only process loops that have a
644 -- single exit condition (either a single EXIT WHEN statement, or a
645 -- WHILE loop not containing any EXIT WHEN statements).
648 Ident : constant Node_Id := Identifier (Loop_Statement);
652 -- If we don't have a proper chain set, ignore call entirely. This
653 -- happens because of previous errors.
655 if No (Entity (Ident))
656 or else Ekind (Entity (Ident)) /= E_Loop
658 Check_Error_Detected;
662 -- Otherwise prepare to scan list of EXIT statements
664 Exit_Stmt := First_Exit_Statement (Entity (Ident));
665 while Present (Exit_Stmt) loop
667 -- Check for EXIT WHEN
669 if Present (Condition (Exit_Stmt)) then
671 -- Quit processing if EXIT WHEN in WHILE loop, or more than
672 -- one EXIT WHEN statement present in the loop.
674 if Present (Expression) then
677 -- Otherwise capture condition from EXIT WHEN statement
680 Expression := Condition (Exit_Stmt);
683 -- If an unconditional exit statement is the last statement in the
684 -- loop, assume that no warning is needed, without any attempt at
685 -- checking whether the exit is reachable.
687 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then
691 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
695 -- Return if no condition to test
697 if No (Expression) then
701 -- Initial conditions met, see if condition is of right form
703 Find_Var (Expression);
705 -- Nothing to do if local variable from source not found. If it's a
706 -- renaming, it is probably renaming something too complicated to deal
710 or else Ekind (Var) /= E_Variable
711 or else Is_Library_Level_Entity (Var)
712 or else not Comes_From_Source (Var)
713 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
717 -- Nothing to do if there is some indirection involved (assume that the
718 -- designated variable might be modified in some way we don't see).
719 -- However, if no function call was found, then we don't care about
720 -- indirections, because the condition must be something like "while X
721 -- /= null loop", so we don't care if X.all is modified in the loop.
723 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
726 -- Same sort of thing for volatile variable, might be modified by
727 -- some other task or by the operating system in some way.
729 elsif Is_Volatile (Var) then
733 -- Filter out case of original statement sequence starting with delay.
734 -- We assume this is a multi-tasking program and that the condition
735 -- is affected by other threads (some kind of busy wait).
738 Fstm : constant Node_Id :=
739 Original_Node (First (Statements (Loop_Statement)));
741 if Nkind (Fstm) = N_Delay_Relative_Statement
742 or else Nkind (Fstm) = N_Delay_Until_Statement
748 -- We have a variable reference of the right form, now we scan the loop
749 -- body to see if it looks like it might not be modified
751 if No_Ref_Found (Loop_Statement) = OK then
753 ("??variable& is not modified in loop body!", Ref, Var);
755 ("\??possible infinite loop!", Ref);
757 end Check_Infinite_Loop_Warning;
759 ----------------------------
760 -- Check_Low_Bound_Tested --
761 ----------------------------
763 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
764 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id);
765 -- Determine whether operand Opnd denotes attribute 'First whose prefix
766 -- is a formal parameter. If this is the case, mark the entity of the
767 -- prefix as having its low bound tested.
769 --------------------------------
770 -- Check_Low_Bound_Tested_For --
771 --------------------------------
773 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id) is
775 if Nkind (Opnd) = N_Attribute_Reference
776 and then Attribute_Name (Opnd) = Name_First
777 and then Is_Entity_Name (Prefix (Opnd))
778 and then Present (Entity (Prefix (Opnd)))
779 and then Is_Formal (Entity (Prefix (Opnd)))
781 Set_Low_Bound_Tested (Entity (Prefix (Opnd)));
783 end Check_Low_Bound_Tested_For;
785 -- Start of processing for Check_Low_Bound_Tested
788 if Comes_From_Source (Expr) then
789 Check_Low_Bound_Tested_For (Left_Opnd (Expr));
790 Check_Low_Bound_Tested_For (Right_Opnd (Expr));
792 end Check_Low_Bound_Tested;
794 ----------------------
795 -- Check_References --
796 ----------------------
798 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
805 Accept_Statement : Node_Id) return Entity_Id;
806 -- For an entry formal entity from an entry declaration, find the
807 -- corresponding body formal from the given accept statement.
809 procedure May_Need_Initialized_Actual (Ent : Entity_Id);
810 -- If an entity of a generic type has default initialization, then the
811 -- corresponding actual type should be fully initialized, or else there
812 -- will be uninitialized components in the instantiation, that might go
813 -- unreported. This routine marks the type of the uninitialized variable
814 -- appropriately to allow the compiler to emit an appropriate warning
815 -- in the instance. In a sense, the use of a type that requires full
816 -- initialization is a weak part of the generic contract.
818 function Missing_Subunits return Boolean;
819 -- We suppress warnings when there are missing subunits, because this
820 -- may generate too many false positives: entities in a parent may only
821 -- be referenced in one of the subunits. We make an exception for
822 -- subunits that contain no other stubs.
824 procedure Output_Reference_Error (M : String);
825 -- Used to output an error message. Deals with posting the error on the
826 -- body formal in the accept case.
828 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
829 -- This is true if the entity in question is potentially referenceable
830 -- from another unit. This is true for entities in packages that are at
831 -- the library level.
833 function Warnings_Off_E1 return Boolean;
834 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
835 -- or for the base type of E1T.
843 Accept_Statement : Node_Id) return Entity_Id
845 Body_Param : Node_Id;
849 -- Loop to find matching parameter in accept statement
851 Body_Param := First (Parameter_Specifications (Accept_Statement));
852 while Present (Body_Param) loop
853 Body_E := Defining_Identifier (Body_Param);
855 if Chars (Body_E) = Chars (E) then
862 -- Should never fall through, should always find a match
867 ---------------------------------
868 -- May_Need_Initialized_Actual --
869 ---------------------------------
871 procedure May_Need_Initialized_Actual (Ent : Entity_Id) is
872 T : constant Entity_Id := Etype (Ent);
873 Par : constant Node_Id := Parent (T);
876 if not Is_Generic_Type (T) then
879 elsif (Nkind (Par)) = N_Private_Extension_Declaration then
881 -- We only indicate the first such variable in the generic.
883 if No (Uninitialized_Variable (Par)) then
884 Set_Uninitialized_Variable (Par, Ent);
887 elsif (Nkind (Par)) = N_Formal_Type_Declaration
888 and then Nkind (Formal_Type_Definition (Par)) =
889 N_Formal_Private_Type_Definition
891 if No (Uninitialized_Variable (Formal_Type_Definition (Par))) then
892 Set_Uninitialized_Variable (Formal_Type_Definition (Par), Ent);
895 end May_Need_Initialized_Actual;
897 ----------------------
898 -- Missing_Subunits --
899 ----------------------
901 function Missing_Subunits return Boolean is
905 if not Unloaded_Subunits then
907 -- Normal compilation, all subunits are present
911 elsif E /= Main_Unit_Entity then
913 -- No warnings on a stub that is not the main unit
917 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
918 D := First (Declarations (Unit_Declaration_Node (E)));
919 while Present (D) loop
921 -- No warnings if the proper body contains nested stubs
923 if Nkind (D) in N_Body_Stub then
933 -- Missing stubs elsewhere
937 end Missing_Subunits;
939 ----------------------------
940 -- Output_Reference_Error --
941 ----------------------------
943 procedure Output_Reference_Error (M : String) is
945 -- Never issue messages for internal names or renamings
947 if Is_Internal_Name (Chars (E1))
948 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
953 -- Don't output message for IN OUT formal unless we have the warning
954 -- flag specifically set. It is a bit odd to distinguish IN OUT
955 -- formals from other cases. This distinction is historical in
956 -- nature. Warnings for IN OUT formals were added fairly late.
958 if Ekind (E1) = E_In_Out_Parameter
959 and then not Check_Unreferenced_Formals
964 -- Other than accept case, post error on defining identifier
969 -- Accept case, find body formal to post the message
972 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
975 end Output_Reference_Error;
977 ----------------------------
978 -- Publicly_Referenceable --
979 ----------------------------
981 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
986 -- A formal parameter is never referenceable outside the body of its
987 -- subprogram or entry.
989 if Is_Formal (Ent) then
993 -- Examine parents to look for a library level package spec. But if
994 -- we find a body or block or other similar construct along the way,
995 -- we cannot be referenced.
1002 -- If we get to top of tree, then publicly referenceable
1007 -- If we reach a generic package declaration, then always
1008 -- consider this referenceable, since any instantiation will
1009 -- have access to the entities in the generic package. Note
1010 -- that the package itself may not be instantiated, but then
1011 -- we will get a warning for the package entity.
1013 -- Note that generic formal parameters are themselves not
1014 -- publicly referenceable in an instance, and warnings on them
1017 when N_Generic_Package_Declaration =>
1019 not Is_List_Member (Prev)
1020 or else List_Containing (Prev) /=
1021 Generic_Formal_Declarations (P);
1023 -- Similarly, the generic formals of a generic subprogram are
1026 when N_Generic_Subprogram_Declaration =>
1027 if Is_List_Member (Prev)
1028 and then List_Containing (Prev) =
1029 Generic_Formal_Declarations (P)
1036 -- If we reach a subprogram body, entity is not referenceable
1037 -- unless it is the defining entity of the body. This will
1038 -- happen, e.g. when a function is an attribute renaming that
1039 -- is rewritten as a body.
1041 when N_Subprogram_Body =>
1042 if Ent /= Defining_Entity (P) then
1048 -- If we reach any other body, definitely not referenceable
1050 when N_Block_Statement
1059 -- For all other cases, keep looking up tree
1066 end Publicly_Referenceable;
1068 ---------------------
1069 -- Warnings_Off_E1 --
1070 ---------------------
1072 function Warnings_Off_E1 return Boolean is
1074 return Has_Warnings_Off (E1T)
1075 or else Has_Warnings_Off (Base_Type (E1T))
1076 or else Warnings_Off_Check_Spec (E1);
1077 end Warnings_Off_E1;
1079 -- Start of processing for Check_References
1082 Process_Deferred_References;
1084 -- No messages if warnings are suppressed, or if we have detected any
1085 -- real errors so far (this last check avoids junk messages resulting
1086 -- from errors, e.g. a subunit that is not loaded).
1088 if Warning_Mode = Suppress or else Serious_Errors_Detected /= 0 then
1092 -- We also skip the messages if any subunits were not loaded (see
1093 -- comment in Sem_Ch10 to understand how this is set, and why it is
1094 -- necessary to suppress the warnings in this case).
1096 if Missing_Subunits then
1100 -- Otherwise loop through entities, looking for suspicious stuff
1102 E1 := First_Entity (E);
1103 while Present (E1) loop
1106 -- We are only interested in source entities. We also don't issue
1107 -- warnings within instances, since the proper place for such
1108 -- warnings is on the template when it is compiled, and we don't
1109 -- issue warnings for variables with names like Junk, Discard etc.
1111 if Comes_From_Source (E1)
1112 and then Instantiation_Location (Sloc (E1)) = No_Location
1114 -- We are interested in variables and out/in-out parameters, but
1115 -- we exclude protected types, too complicated to worry about.
1117 if Ekind (E1) = E_Variable
1119 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1120 and then not Is_Protected_Type (Current_Scope))
1122 -- If the formal has a class-wide type, retrieve its type
1123 -- because checks below depend on its private nature.
1125 if Is_Class_Wide_Type (E1T) then
1129 -- Case of an unassigned variable
1131 -- First gather any Unset_Reference indication for E1. In the
1132 -- case of a parameter, it is the Spec_Entity that is relevant.
1134 if Ekind (E1) = E_Out_Parameter
1135 and then Present (Spec_Entity (E1))
1137 UR := Unset_Reference (Spec_Entity (E1));
1139 UR := Unset_Reference (E1);
1142 -- Special processing for access types
1144 if Present (UR) and then Is_Access_Type (E1T) then
1146 -- For access types, the only time we made a UR entry was
1147 -- for a dereference, and so we post the appropriate warning
1148 -- here (note that the dereference may not be explicit in
1149 -- the source, for example in the case of a dispatching call
1150 -- with an anonymous access controlling formal, or of an
1151 -- assignment of a pointer involving discriminant check on
1152 -- the designated object).
1154 if not Warnings_Off_E1 then
1155 Error_Msg_NE ("??& may be null!", UR, E1);
1160 -- Case of variable that could be a constant. Note that we
1161 -- never signal such messages for generic package entities,
1162 -- since a given instance could have modifications outside
1165 -- Note that we used to check Address_Taken here, but we don't
1166 -- want to do that since it can be set for non-source cases,
1167 -- e.g. the Unrestricted_Access from a valid attribute, and
1168 -- the wanted effect is included in Never_Set_In_Source.
1170 elsif Warn_On_Constant
1171 and then (Ekind (E1) = E_Variable
1172 and then Has_Initial_Value (E1))
1173 and then Never_Set_In_Source_Check_Spec (E1)
1174 and then not Generic_Package_Spec_Entity (E1)
1176 -- A special case, if this variable is volatile and not
1177 -- imported, it is not helpful to tell the programmer
1178 -- to mark the variable as constant, since this would be
1179 -- illegal by virtue of RM C.6(13). Instead we suggest
1180 -- using pragma Export (can't be Import because of the
1183 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1184 and then not Is_Imported (E1)
1187 ("?k?& is not modified, consider pragma Export for "
1188 & "volatile variable!", E1);
1190 -- Another special case, Exception_Occurrence, this catches
1191 -- the case of exception choice (and a bit more too, but not
1192 -- worth doing more investigation here).
1194 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1197 -- Here we give the warning if referenced and no pragma
1198 -- Unreferenced or Unmodified is present.
1203 if Ekind (E1) = E_Variable then
1204 if Referenced_Check_Spec (E1)
1205 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1206 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1208 if not Warnings_Off_E1
1209 and then not Has_Junk_Name (E1)
1211 Error_Msg_N -- CODEFIX
1212 ("?k?& is not modified, "
1213 & "could be declared constant!",
1220 -- Other cases of a variable or parameter never set in source
1222 elsif Never_Set_In_Source_Check_Spec (E1)
1224 -- No warning if warning for this case turned off
1226 and then Warn_On_No_Value_Assigned
1228 -- No warning if address taken somewhere
1230 and then not Address_Taken (E1)
1232 -- No warning if explicit initial value
1234 and then not Has_Initial_Value (E1)
1236 -- No warning for generic package spec entities, since we
1237 -- might set them in a child unit or something like that
1239 and then not Generic_Package_Spec_Entity (E1)
1241 -- No warning if fully initialized type, except that for
1242 -- this purpose we do not consider access types to qualify
1243 -- as fully initialized types (relying on an access type
1244 -- variable being null when it is never set is a bit odd).
1246 -- Also we generate warning for an out parameter that is
1247 -- never referenced, since again it seems odd to rely on
1248 -- default initialization to set an out parameter value.
1250 and then (Is_Access_Type (E1T)
1251 or else Ekind (E1) = E_Out_Parameter
1252 or else not Is_Fully_Initialized_Type (E1T))
1254 -- Do not output complaint about never being assigned a
1255 -- value if a pragma Unmodified applies to the variable
1256 -- we are examining, or if it is a parameter, if there is
1257 -- a pragma Unreferenced for the corresponding spec, or
1258 -- if the type is marked as having unreferenced objects.
1259 -- The last is a little peculiar, but better too few than
1260 -- too many warnings in this situation.
1262 if Has_Pragma_Unreferenced_Objects (E1T)
1263 or else Has_Pragma_Unmodified_Check_Spec (E1)
1267 -- IN OUT parameter case where parameter is referenced. We
1268 -- separate this out, since this is the case where we delay
1269 -- output of the warning until more information is available
1270 -- (about use in an instantiation or address being taken).
1272 elsif Ekind (E1) = E_In_Out_Parameter
1273 and then Referenced_Check_Spec (E1)
1275 -- Suppress warning if private type, and the procedure
1276 -- has a separate declaration in a different unit. This
1277 -- is the case where the client of a package sees only
1278 -- the private type, and it may be quite reasonable
1279 -- for the logical view to be IN OUT, even if the
1280 -- implementation ends up using access types or some
1281 -- other method to achieve the local effect of a
1282 -- modification. On the other hand if the spec and body
1283 -- are in the same unit, we are in the package body and
1284 -- there we have less excuse for a junk IN OUT parameter.
1286 if Has_Private_Declaration (E1T)
1287 and then Present (Spec_Entity (E1))
1288 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1292 -- Suppress warning for any parameter of a dispatching
1293 -- operation, since it is quite reasonable to have an
1294 -- operation that is overridden, and for some subclasses
1295 -- needs the formal to be IN OUT and for others happens
1296 -- not to assign it.
1298 elsif Is_Dispatching_Operation
1299 (Scope (Goto_Spec_Entity (E1)))
1303 -- Suppress warning if composite type contains any access
1304 -- component, since the logical effect of modifying a
1305 -- parameter may be achieved by modifying a referenced
1308 elsif Is_Composite_Type (E1T)
1309 and then Has_Access_Values (E1T)
1313 -- Suppress warning on formals of an entry body. All
1314 -- references are attached to the formal in the entry
1315 -- declaration, which are marked Is_Entry_Formal.
1317 elsif Ekind (Scope (E1)) = E_Entry
1318 and then not Is_Entry_Formal (E1)
1322 -- OK, looks like warning for an IN OUT parameter that
1323 -- could be IN makes sense, but we delay the output of
1324 -- the warning, pending possibly finding out later on
1325 -- that the associated subprogram is used as a generic
1326 -- actual, or its address/access is taken. In these two
1327 -- cases, we suppress the warning because the context may
1328 -- force use of IN OUT, even if in this particular case
1329 -- the formal is not modified.
1332 -- Suppress the warnings for a junk name
1334 if not Has_Junk_Name (E1) then
1335 In_Out_Warnings.Append (E1);
1339 -- Other cases of formals
1341 elsif Is_Formal (E1) then
1342 if not Is_Trivial_Subprogram (Scope (E1)) then
1343 if Referenced_Check_Spec (E1) then
1344 if not Has_Pragma_Unmodified_Check_Spec (E1)
1345 and then not Warnings_Off_E1
1346 and then not Has_Junk_Name (E1)
1348 Output_Reference_Error
1349 ("?f?formal parameter& is read but "
1350 & "never assigned!");
1353 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1354 and then not Warnings_Off_E1
1355 and then not Has_Junk_Name (E1)
1357 Output_Reference_Error
1358 ("?f?formal parameter& is not referenced!");
1365 if Referenced (E1) then
1366 if not Has_Unmodified (E1)
1367 and then not Warnings_Off_E1
1368 and then not Has_Junk_Name (E1)
1370 Output_Reference_Error
1371 ("?v?variable& is read but never assigned!");
1372 May_Need_Initialized_Actual (E1);
1375 elsif not Has_Unreferenced (E1)
1376 and then not Warnings_Off_E1
1377 and then not Has_Junk_Name (E1)
1379 Output_Reference_Error -- CODEFIX
1380 ("?v?variable& is never read and never assigned!");
1383 -- Deal with special case where this variable is hidden
1384 -- by a loop variable.
1386 if Ekind (E1) = E_Variable
1387 and then Present (Hiding_Loop_Variable (E1))
1388 and then not Warnings_Off_E1
1391 ("?v?for loop implicitly declares loop variable!",
1392 Hiding_Loop_Variable (E1));
1394 Error_Msg_Sloc := Sloc (E1);
1396 ("\?v?declaration hides & declared#!",
1397 Hiding_Loop_Variable (E1));
1404 -- Check for unset reference
1406 if Warn_On_No_Value_Assigned and then Present (UR) then
1408 -- For other than access type, go back to original node to
1409 -- deal with case where original unset reference has been
1410 -- rewritten during expansion.
1412 -- In some cases, the original node may be a type
1413 -- conversion, a qualification or an attribute reference and
1414 -- in this case we want the object entity inside. Same for
1415 -- an expression with actions.
1417 UR := Original_Node (UR);
1419 if Nkind_In (UR, N_Expression_With_Actions,
1420 N_Qualified_Expression,
1423 UR := Expression (UR);
1425 elsif Nkind (UR) = N_Attribute_Reference then
1433 -- Don't issue warning if appearing inside Initial_Condition
1434 -- pragma or aspect, since that expression is not evaluated
1435 -- at the point where it occurs in the source.
1437 if In_Pragma_Expression (UR, Name_Initial_Condition) then
1441 -- Here we issue the warning, all checks completed
1443 -- If we have a return statement, this was a case of an OUT
1444 -- parameter not being set at the time of the return. (Note:
1445 -- it can't be N_Extended_Return_Statement, because those
1446 -- are only for functions, and functions do not allow OUT
1449 if not Is_Trivial_Subprogram (Scope (E1)) then
1450 if Nkind (UR) = N_Simple_Return_Statement
1451 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1453 if not Warnings_Off_E1
1454 and then not Has_Junk_Name (E1)
1457 ("?v?OUT parameter& not set before return",
1461 -- If the unset reference is a selected component
1462 -- prefix from source, mention the component as well.
1463 -- If the selected component comes from expansion, all
1464 -- we know is that the entity is not fully initialized
1465 -- at the point of the reference. Locate a random
1466 -- uninitialized component to get a better message.
1468 elsif Nkind (Parent (UR)) = N_Selected_Component then
1469 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1471 if not Comes_From_Source (Parent (UR)) then
1476 Comp := First_Entity (E1T);
1477 while Present (Comp) loop
1478 if Ekind (Comp) = E_Component
1479 and then Nkind (Parent (Comp)) =
1480 N_Component_Declaration
1481 and then No (Expression (Parent (Comp)))
1483 Error_Msg_Node_2 := Comp;
1492 -- Issue proper warning. This is a case of referencing
1493 -- a variable before it has been explicitly assigned.
1494 -- For access types, UR was only set for dereferences,
1495 -- so the issue is that the value may be null.
1497 if not Is_Trivial_Subprogram (Scope (E1)) then
1498 if not Warnings_Off_E1 then
1499 if Is_Access_Type (Etype (Parent (UR))) then
1500 Error_Msg_N ("??`&.&` may be null!", UR);
1503 ("??`&.&` may be referenced before "
1504 & "it has a value!", UR);
1509 -- All other cases of unset reference active
1511 elsif not Warnings_Off_E1 then
1513 ("??& may be referenced before it has a value!", UR);
1522 -- Then check for unreferenced entities. Note that we are only
1523 -- interested in entities whose Referenced flag is not set.
1525 if not Referenced_Check_Spec (E1)
1527 -- If Referenced_As_LHS is set, then that's still interesting
1528 -- (potential "assigned but never read" case), but not if we
1529 -- have pragma Unreferenced, which cancels this warning.
1531 and then (not Referenced_As_LHS_Check_Spec (E1)
1532 or else not Has_Unreferenced (E1))
1534 -- Check that warnings on unreferenced entities are enabled
1537 ((Check_Unreferenced and then not Is_Formal (E1))
1539 -- Case of warning on unreferenced formal
1541 or else (Check_Unreferenced_Formals and then Is_Formal (E1))
1543 -- Case of warning on unread variables modified by an
1544 -- assignment, or an OUT parameter if it is the only one.
1546 or else (Warn_On_Modified_Unread
1547 and then Referenced_As_LHS_Check_Spec (E1))
1549 -- Case of warning on any unread OUT parameter (note such
1550 -- indications are only set if the appropriate warning
1551 -- options were set, so no need to recheck here.)
1553 or else Referenced_As_Out_Parameter_Check_Spec (E1))
1555 -- All other entities, including local packages that cannot be
1556 -- referenced from elsewhere, including those declared within a
1559 and then (Is_Object (E1)
1560 or else Is_Type (E1)
1561 or else Ekind (E1) = E_Label
1562 or else Ekind_In (E1, E_Exception,
1565 or else Is_Overloadable (E1)
1567 -- Package case, if the main unit is a package spec
1568 -- or generic package spec, then there may be a
1569 -- corresponding body that references this package
1570 -- in some other file. Otherwise we can be sure
1571 -- that there is no other reference.
1574 (Ekind (E1) = E_Package
1576 not Is_Package_Or_Generic_Package
1577 (Cunit_Entity (Current_Sem_Unit))))
1579 -- Exclude instantiations, since there is no reason why every
1580 -- entity in an instantiation should be referenced.
1582 and then Instantiation_Location (Sloc (E1)) = No_Location
1584 -- Exclude formal parameters from bodies if the corresponding
1585 -- spec entity has been referenced in the case where there is
1588 and then not (Is_Formal (E1)
1589 and then Ekind (Scope (E1)) = E_Subprogram_Body
1590 and then Present (Spec_Entity (E1))
1591 and then Referenced (Spec_Entity (E1)))
1593 -- Consider private type referenced if full view is referenced.
1594 -- If there is not full view, this is a generic type on which
1595 -- warnings are also useful.
1598 not (Is_Private_Type (E1)
1599 and then Present (Full_View (E1))
1600 and then Referenced (Full_View (E1)))
1602 -- Don't worry about full view, only about private type
1604 and then not Has_Private_Declaration (E1)
1606 -- Eliminate dispatching operations from consideration, we
1607 -- cannot tell if these are referenced or not in any easy
1608 -- manner (note this also catches Adjust/Finalize/Initialize).
1610 and then not Is_Dispatching_Operation (E1)
1612 -- Check entity that can be publicly referenced (we do not give
1613 -- messages for such entities, since there could be other
1614 -- units, not involved in this compilation, that contain
1615 -- relevant references.
1617 and then not Publicly_Referenceable (E1)
1619 -- Class wide types are marked as source entities, but they are
1620 -- not really source entities, and are always created, so we do
1621 -- not care if they are not referenced.
1623 and then Ekind (E1) /= E_Class_Wide_Type
1625 -- Objects other than parameters of task types are allowed to
1626 -- be non-referenced, since they start up tasks.
1628 and then ((Ekind (E1) /= E_Variable
1629 and then Ekind (E1) /= E_Constant
1630 and then Ekind (E1) /= E_Component)
1631 or else not Is_Task_Type (E1T))
1633 -- For subunits, only place warnings on the main unit itself,
1634 -- since parent units are not completely compiled.
1636 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1637 or else Get_Source_Unit (E1) = Main_Unit)
1639 -- No warning on a return object, because these are often
1640 -- created with a single expression and an implicit return.
1641 -- If the object is a variable there will be a warning
1642 -- indicating that it could be declared constant.
1645 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1647 -- Suppress warnings in internal units if not in -gnatg mode
1648 -- (these would be junk warnings for an applications program,
1649 -- since they refer to problems in internal units).
1651 if GNAT_Mode or else not In_Internal_Unit (E1) then
1652 -- We do not immediately flag the error. This is because we
1653 -- have not expanded generic bodies yet, and they may have
1654 -- the missing reference. So instead we park the entity on a
1655 -- list, for later processing. However for the case of an
1656 -- accept statement we want to output messages now, since
1657 -- we know we already have all information at hand, and we
1658 -- also want to have separate warnings for each accept
1659 -- statement for the same entry.
1661 if Present (Anod) then
1662 pragma Assert (Is_Formal (E1));
1664 -- The unreferenced entity is E1, but post the warning
1665 -- on the body entity for this accept statement.
1667 if not Warnings_Off_E1 then
1668 Warn_On_Unreferenced_Entity
1669 (E1, Body_Formal (E1, Accept_Statement => Anod));
1672 elsif not Warnings_Off_E1
1673 and then not Has_Junk_Name (E1)
1675 Unreferenced_Entities.Append (E1);
1679 -- Generic units are referenced in the generic body, but if they
1680 -- are not public and never instantiated we want to force a
1681 -- warning on them. We treat them as redundant constructs to
1684 elsif Is_Generic_Subprogram (E1)
1685 and then not Is_Instantiated (E1)
1686 and then not Publicly_Referenceable (E1)
1687 and then Instantiation_Depth (Sloc (E1)) = 0
1688 and then Warn_On_Redundant_Constructs
1690 if not Warnings_Off_E1 and then not Has_Junk_Name (E1) then
1691 Unreferenced_Entities.Append (E1);
1693 -- Force warning on entity
1695 Set_Referenced (E1, False);
1700 -- Recurse into nested package or block. Do not recurse into a formal
1701 -- package, because the corresponding body is not analyzed.
1704 if (Is_Package_Or_Generic_Package (E1)
1705 and then Nkind (Parent (E1)) = N_Package_Specification
1707 Nkind (Original_Node (Unit_Declaration_Node (E1))) /=
1708 N_Formal_Package_Declaration)
1710 or else Ekind (E1) = E_Block
1712 Check_References (E1);
1717 end Check_References;
1719 ---------------------------
1720 -- Check_Unset_Reference --
1721 ---------------------------
1723 procedure Check_Unset_Reference (N : Node_Id) is
1724 Typ : constant Entity_Id := Etype (N);
1726 function Is_OK_Fully_Initialized return Boolean;
1727 -- This function returns true if the given node N is fully initialized
1728 -- so that the reference is safe as far as this routine is concerned.
1729 -- Safe generally means that the type of N is a fully initialized type.
1730 -- The one special case is that for access types, which are always fully
1731 -- initialized, we don't consider a dereference OK since it will surely
1732 -- be dereferencing a null value, which won't do.
1734 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1735 -- Used to test indexed or selected component or slice to see if the
1736 -- evaluation of the prefix depends on a dereference, and if so, returns
1737 -- True, in which case we always check the prefix, even if we know that
1738 -- the referenced component is initialized. Pref is the prefix to test.
1740 -----------------------------
1741 -- Is_OK_Fully_Initialized --
1742 -----------------------------
1744 function Is_OK_Fully_Initialized return Boolean is
1748 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1751 -- A type subject to pragma Default_Initial_Condition is fully
1752 -- default initialized when the pragma appears with a non-null
1753 -- argument (SPARK RM 3.1 and SPARK RM 7.3.3).
1755 elsif Has_DIC (Typ) then
1756 Prag := Get_Pragma (Typ, Pragma_Default_Initial_Condition);
1757 pragma Assert (Present (Prag));
1759 return Is_Verifiable_DIC_Pragma (Prag);
1762 return Is_Fully_Initialized_Type (Typ);
1764 end Is_OK_Fully_Initialized;
1766 ----------------------------
1767 -- Prefix_Has_Dereference --
1768 ----------------------------
1770 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1772 -- If prefix is of an access type, it certainly needs a dereference
1774 if Is_Access_Type (Etype (Pref)) then
1777 -- If prefix is explicit dereference, that's a dereference for sure
1779 elsif Nkind (Pref) = N_Explicit_Dereference then
1782 -- If prefix is itself a component reference or slice check prefix
1784 elsif Nkind (Pref) = N_Slice
1785 or else Nkind (Pref) = N_Indexed_Component
1786 or else Nkind (Pref) = N_Selected_Component
1788 return Prefix_Has_Dereference (Prefix (Pref));
1790 -- All other cases do not involve a dereference
1795 end Prefix_Has_Dereference;
1797 -- Start of processing for Check_Unset_Reference
1800 -- Nothing to do if warnings suppressed
1802 if Warning_Mode = Suppress then
1806 -- Nothing to do for numeric or string literal. Do this test early to
1807 -- save time in a common case (it does not matter that we do not include
1808 -- character literal here, since that will be caught later on in the
1809 -- when others branch of the case statement).
1811 if Nkind (N) in N_Numeric_Or_String_Literal then
1815 -- Ignore reference unless it comes from source. Almost always if we
1816 -- have a reference from generated code, it is bogus (e.g. calls to init
1817 -- procs to set default discriminant values).
1819 if not Comes_From_Source (N) then
1823 -- Otherwise see what kind of node we have. If the entity already has an
1824 -- unset reference, it is not necessarily the earliest in the text,
1825 -- because resolution of the prefix of selected components is completed
1826 -- before the resolution of the selected component itself. As a result,
1827 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1828 -- in right-to-left order. If there is already an unset reference, we
1829 -- check whether N is earlier before proceeding.
1833 -- For identifier or expanded name, examine the entity involved
1835 when N_Expanded_Name
1839 E : constant Entity_Id := Entity (N);
1842 if Ekind_In (E, E_Variable, E_Out_Parameter)
1843 and then Never_Set_In_Source_Check_Spec (E)
1844 and then not Has_Initial_Value (E)
1845 and then (No (Unset_Reference (E))
1847 Earlier_In_Extended_Unit
1848 (Sloc (N), Sloc (Unset_Reference (E))))
1849 and then not Has_Pragma_Unmodified_Check_Spec (E)
1850 and then not Warnings_Off_Check_Spec (E)
1851 and then not Has_Junk_Name (E)
1853 -- We may have an unset reference. The first test is whether
1854 -- this is an access to a discriminant of a record or a
1855 -- component with default initialization. Both of these
1856 -- cases can be ignored, since the actual object that is
1857 -- referenced is definitely initialized. Note that this
1858 -- covers the case of reading discriminants of an OUT
1859 -- parameter, which is OK even in Ada 83.
1861 -- Note that we are only interested in a direct reference to
1862 -- a record component here. If the reference is through an
1863 -- access type, then the access object is being referenced,
1864 -- not the record, and still deserves an unset reference.
1866 if Nkind (Parent (N)) = N_Selected_Component
1867 and not Is_Access_Type (Typ)
1870 ES : constant Entity_Id :=
1871 Entity (Selector_Name (Parent (N)));
1873 if Ekind (ES) = E_Discriminant
1875 (Present (Declaration_Node (ES))
1877 Present (Expression (Declaration_Node (ES))))
1884 -- Exclude fully initialized types
1886 if Is_OK_Fully_Initialized then
1890 -- Here we have a potential unset reference. But before we
1891 -- get worried about it, we have to make sure that the
1892 -- entity declaration is in the same procedure as the
1893 -- reference, since if they are in separate procedures, then
1894 -- we have no idea about sequential execution.
1896 -- The tests in the loop below catch all such cases, but do
1897 -- allow the reference to appear in a loop, block, or
1898 -- package spec that is nested within the declaring scope.
1899 -- As always, it is possible to construct cases where the
1900 -- warning is wrong, that is why it is a warning.
1902 Potential_Unset_Reference : declare
1904 SE : constant Entity_Id := Scope (E);
1906 function Within_Postcondition return Boolean;
1907 -- Returns True if N is within a Postcondition, a
1908 -- Refined_Post, an Ensures component in a Test_Case,
1909 -- or a Contract_Cases.
1911 --------------------------
1912 -- Within_Postcondition --
1913 --------------------------
1915 function Within_Postcondition return Boolean is
1920 while Present (Nod) loop
1921 if Nkind (Nod) = N_Pragma
1922 and then Nam_In (Pragma_Name_Unmapped (Nod),
1925 Name_Contract_Cases)
1929 elsif Present (Parent (Nod)) then
1932 if Nkind (P) = N_Pragma
1933 and then Pragma_Name (P) =
1935 and then Nod = Test_Case_Arg (P, Name_Ensures)
1941 Nod := Parent (Nod);
1945 end Within_Postcondition;
1947 -- Start of processing for Potential_Unset_Reference
1950 SR := Current_Scope;
1952 if SR = Standard_Standard
1953 or else Is_Subprogram (SR)
1954 or else Is_Concurrent_Body (SR)
1955 or else Is_Concurrent_Type (SR)
1963 -- Case of reference has an access type. This is a
1964 -- special case since access types are always set to null
1965 -- so cannot be truly uninitialized, but we still want to
1966 -- warn about cases of obvious null dereference.
1968 if Is_Access_Type (Typ) then
1969 Access_Type_Case : declare
1973 (N : Node_Id) return Traverse_Result;
1974 -- Process function for instantiation of Traverse
1975 -- below. Checks if N contains reference to E other
1976 -- than a dereference.
1978 function Ref_In (Nod : Node_Id) return Boolean;
1979 -- Determines whether Nod contains a reference to
1980 -- the entity E that is not a dereference.
1987 (N : Node_Id) return Traverse_Result
1990 if Is_Entity_Name (N)
1991 and then Entity (N) = E
1992 and then not Is_Dereferenced (N)
2004 function Ref_In (Nod : Node_Id) return Boolean is
2005 function Traverse is new Traverse_Func (Process);
2007 return Traverse (Nod) = Abandon;
2010 -- Start of processing for Access_Type_Case
2013 -- Don't bother if we are inside an instance, since
2014 -- the compilation of the generic template is where
2015 -- the warning should be issued.
2021 -- Don't bother if this is not the main unit. If we
2022 -- try to give this warning for with'ed units, we
2023 -- get some false positives, since we do not record
2024 -- references in other units.
2026 if not In_Extended_Main_Source_Unit (E)
2028 not In_Extended_Main_Source_Unit (N)
2033 -- We are only interested in dereferences
2035 if not Is_Dereferenced (N) then
2039 -- One more check, don't bother with references
2040 -- that are inside conditional statements or WHILE
2041 -- loops if the condition references the entity in
2042 -- question. This avoids most false positives.
2049 if Nkind_In (P, N_If_Statement, N_Elsif_Part)
2050 and then Ref_In (Condition (P))
2054 elsif Nkind (P) = N_Loop_Statement
2055 and then Present (Iteration_Scheme (P))
2057 Ref_In (Condition (Iteration_Scheme (P)))
2062 end Access_Type_Case;
2065 -- One more check, don't bother if we are within a
2066 -- postcondition, since the expression occurs in a
2067 -- place unrelated to the actual test.
2069 if not Within_Postcondition then
2071 -- Here we definitely have a case for giving a warning
2072 -- for a reference to an unset value. But we don't
2073 -- give the warning now. Instead set Unset_Reference
2074 -- in the identifier involved. The reason for this is
2075 -- that if we find the variable is never ever assigned
2076 -- a value then that warning is more important and
2077 -- there is no point in giving the reference warning.
2079 -- If this is an identifier, set the field directly
2081 if Nkind (N) = N_Identifier then
2082 Set_Unset_Reference (E, N);
2084 -- Otherwise it is an expanded name, so set the field
2085 -- of the actual identifier for the reference.
2088 Set_Unset_Reference (E, Selector_Name (N));
2091 end Potential_Unset_Reference;
2095 -- Indexed component or slice
2097 when N_Indexed_Component
2100 -- If prefix does not involve dereferencing an access type, then
2101 -- we know we are OK if the component type is fully initialized,
2102 -- since the component will have been set as part of the default
2105 if not Prefix_Has_Dereference (Prefix (N))
2106 and then Is_OK_Fully_Initialized
2110 -- Look at prefix in access type case, or if the component is not
2111 -- fully initialized.
2114 Check_Unset_Reference (Prefix (N));
2119 when N_Selected_Component =>
2121 Pref : constant Node_Id := Prefix (N);
2122 Ent : constant Entity_Id := Entity (Selector_Name (N));
2125 -- If prefix involves dereferencing an access type, always
2126 -- check the prefix, since the issue then is whether this
2127 -- access value is null.
2129 if Prefix_Has_Dereference (Pref) then
2132 -- Always go to prefix if no selector entity is set. Can this
2133 -- happen in the normal case? Not clear, but it definitely can
2134 -- happen in error cases.
2139 -- For a record component, check some cases where we have
2140 -- reasonable cause to consider that the component is known to
2141 -- be or probably is initialized. In this case, we don't care
2142 -- if the prefix itself was explicitly initialized.
2144 -- Discriminants are always considered initialized
2146 elsif Ekind (Ent) = E_Discriminant then
2149 -- An explicitly initialized component is certainly initialized
2151 elsif Nkind (Parent (Ent)) = N_Component_Declaration
2152 and then Present (Expression (Parent (Ent)))
2156 -- A fully initialized component is initialized
2158 elsif Is_OK_Fully_Initialized then
2162 -- If none of those cases apply, check the record type prefix
2164 Check_Unset_Reference (Pref);
2167 -- For type conversions, qualifications, or expressions with actions,
2168 -- examine the expression.
2170 when N_Expression_With_Actions
2171 | N_Qualified_Expression
2174 Check_Unset_Reference (Expression (N));
2176 -- For explicit dereference, always check prefix, which will generate
2177 -- an unset reference (since this is a case of dereferencing null).
2179 when N_Explicit_Dereference =>
2180 Check_Unset_Reference (Prefix (N));
2182 -- All other cases are not cases of an unset reference
2187 end Check_Unset_Reference;
2189 ------------------------
2190 -- Check_Unused_Withs --
2191 ------------------------
2193 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2199 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2200 -- This is needed for checking the special renaming case
2202 procedure Check_One_Unit (Unit : Unit_Number_Type);
2203 -- Subsidiary procedure, performs checks for specified unit
2205 --------------------
2206 -- Check_One_Unit --
2207 --------------------
2209 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2210 Is_Visible_Renaming : Boolean := False;
2213 procedure Check_Inner_Package (Pack : Entity_Id);
2214 -- Pack is a package local to a unit in a with_clause. Both the unit
2215 -- and Pack are referenced. If none of the entities in Pack are
2216 -- referenced, then the only occurrence of Pack is in a USE clause
2217 -- or a pragma, and a warning is worthwhile as well.
2219 function Check_System_Aux return Boolean;
2220 -- Before giving a warning on a with_clause for System, check whether
2221 -- a system extension is present.
2223 function Find_Package_Renaming
2225 L : Entity_Id) return Entity_Id;
2226 -- The only reference to a context unit may be in a renaming
2227 -- declaration. If this renaming declares a visible entity, do not
2228 -- warn that the context clause could be moved to the body, because
2229 -- the renaming may be intended to re-export the unit.
2231 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2232 -- This function determines if a package has any visible entities.
2233 -- True is returned if there is at least one declared visible entity,
2234 -- otherwise False is returned (e.g. case of only pragmas present).
2236 -------------------------
2237 -- Check_Inner_Package --
2238 -------------------------
2240 procedure Check_Inner_Package (Pack : Entity_Id) is
2242 Un : constant Node_Id := Sinfo.Unit (Cnode);
2244 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2245 -- If N is a use_clause for Pack, emit warning
2247 procedure Check_Use_Clauses is new
2248 Traverse_Proc (Check_Use_Clause);
2250 ----------------------
2251 -- Check_Use_Clause --
2252 ----------------------
2254 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2256 if Nkind (N) = N_Use_Package_Clause
2257 and then Entity (Name (N)) = Pack
2259 -- Suppress message if any serious errors detected that turn
2260 -- off expansion, and thus result in false positives for
2263 if Serious_Errors_Detected = 0 then
2264 Error_Msg_Qual_Level := 1;
2265 Error_Msg_NE -- CODEFIX
2266 ("?u?no entities of package& are referenced!",
2268 Error_Msg_Qual_Level := 0;
2273 end Check_Use_Clause;
2275 -- Start of processing for Check_Inner_Package
2278 E := First_Entity (Pack);
2279 while Present (E) loop
2280 if Referenced_Check_Spec (E) then
2287 -- No entities of the package are referenced. Check whether the
2288 -- reference to the package itself is a use clause, and if so
2289 -- place a warning on it.
2291 Check_Use_Clauses (Un);
2292 end Check_Inner_Package;
2294 ----------------------
2295 -- Check_System_Aux --
2296 ----------------------
2298 function Check_System_Aux return Boolean is
2302 if Chars (Lunit) = Name_System
2303 and then Scope (Lunit) = Standard_Standard
2304 and then Present_System_Aux
2306 Ent := First_Entity (System_Aux_Id);
2307 while Present (Ent) loop
2308 if Referenced_Check_Spec (Ent) then
2317 end Check_System_Aux;
2319 ---------------------------
2320 -- Find_Package_Renaming --
2321 ---------------------------
2323 function Find_Package_Renaming
2325 L : Entity_Id) return Entity_Id
2331 Is_Visible_Renaming := False;
2333 E1 := First_Entity (P);
2334 while Present (E1) loop
2335 if Ekind (E1) = E_Package and then Renamed_Object (E1) = L then
2336 Is_Visible_Renaming := not Is_Hidden (E1);
2339 elsif Ekind (E1) = E_Package
2340 and then No (Renamed_Object (E1))
2341 and then not Is_Generic_Instance (E1)
2343 R := Find_Package_Renaming (E1, L);
2346 Is_Visible_Renaming := not Is_Hidden (R);
2355 end Find_Package_Renaming;
2357 --------------------------
2358 -- Has_Visible_Entities --
2359 --------------------------
2361 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2365 -- If unit in context is not a package, it is a subprogram that
2366 -- is not called or a generic unit that is not instantiated
2367 -- in the current unit, and warning is appropriate.
2369 if Ekind (P) /= E_Package then
2373 -- If unit comes from a limited_with clause, look for declaration
2374 -- of shadow entities.
2376 if Present (Limited_View (P)) then
2377 E := First_Entity (Limited_View (P));
2379 E := First_Entity (P);
2382 while Present (E) and then E /= First_Private_Entity (P) loop
2383 if Comes_From_Source (E) or else Present (Limited_View (P)) then
2391 end Has_Visible_Entities;
2393 -- Start of processing for Check_One_Unit
2396 Cnode := Cunit (Unit);
2398 -- Only do check in units that are part of the extended main unit.
2399 -- This is actually a necessary restriction, because in the case of
2400 -- subprogram acting as its own specification, there can be with's in
2401 -- subunits that we will not see.
2403 if not In_Extended_Main_Source_Unit (Cnode) then
2407 -- Loop through context items in this unit
2409 Item := First (Context_Items (Cnode));
2410 while Present (Item) loop
2411 if Nkind (Item) = N_With_Clause
2412 and then not Implicit_With (Item)
2413 and then In_Extended_Main_Source_Unit (Item)
2415 -- Guard for no entity present. Not clear under what conditions
2416 -- this happens, but it does occur, and since this is only a
2417 -- warning, we just suppress the warning in this case.
2419 and then Nkind (Name (Item)) in N_Has_Entity
2420 and then Present (Entity (Name (Item)))
2422 Lunit := Entity (Name (Item));
2424 -- Check if this unit is referenced (skip the check if this
2425 -- is explicitly marked by a pragma Unreferenced).
2427 if not Referenced (Lunit) and then not Has_Unreferenced (Lunit)
2429 -- Suppress warnings in internal units if not in -gnatg mode
2430 -- (these would be junk warnings for an application program,
2431 -- since they refer to problems in internal units).
2433 if GNAT_Mode or else not Is_Internal_Unit (Unit) then
2434 -- Here we definitely have a non-referenced unit. If it
2435 -- is the special call for a spec unit, then just set the
2436 -- flag to be read later.
2438 if Unit = Spec_Unit then
2439 Set_Unreferenced_In_Spec (Item);
2441 -- Otherwise simple unreferenced message, but skip this
2442 -- if no visible entities, because that is most likely a
2443 -- case where warning would be false positive (e.g. a
2444 -- package with only a linker options pragma and nothing
2445 -- else or a pragma elaborate with a body library task).
2447 elsif Has_Visible_Entities (Entity (Name (Item))) then
2448 Error_Msg_N -- CODEFIX
2449 ("?u?unit& is not referenced!", Name (Item));
2453 -- If main unit is a renaming of this unit, then we consider
2454 -- the with to be OK (obviously it is needed in this case).
2455 -- This may be transitive: the unit in the with_clause may
2456 -- itself be a renaming, in which case both it and the main
2457 -- unit rename the same ultimate package.
2459 elsif Present (Renamed_Entity (Munite))
2461 (Renamed_Entity (Munite) = Lunit
2462 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2466 -- If this unit is referenced, and it is a package, we do
2467 -- another test, to see if any of the entities in the package
2468 -- are referenced. If none of the entities are referenced, we
2469 -- still post a warning. This occurs if the only use of the
2470 -- package is in a use clause, or in a package renaming
2471 -- declaration. This check is skipped for packages that are
2472 -- renamed in a spec, since the entities in such a package are
2473 -- visible to clients via the renaming.
2475 elsif Ekind (Lunit) = E_Package
2476 and then not Renamed_In_Spec (Lunit)
2478 -- If Is_Instantiated is set, it means that the package is
2479 -- implicitly instantiated (this is the case of parent
2480 -- instance or an actual for a generic package formal), and
2481 -- this counts as a reference.
2483 if Is_Instantiated (Lunit) then
2486 -- If no entities in package, and there is a pragma
2487 -- Elaborate_Body present, then assume that this with is
2488 -- done for purposes of this elaboration.
2490 elsif No (First_Entity (Lunit))
2491 and then Has_Pragma_Elaborate_Body (Lunit)
2495 -- Otherwise see if any entities have been referenced
2498 if Limited_Present (Item) then
2499 Ent := First_Entity (Limited_View (Lunit));
2501 Ent := First_Entity (Lunit);
2505 -- No more entities, and we did not find one that was
2506 -- referenced. Means we have a definite case of a with
2507 -- none of whose entities was referenced.
2511 -- If in spec, just set the flag
2513 if Unit = Spec_Unit then
2514 Set_No_Entities_Ref_In_Spec (Item);
2516 elsif Check_System_Aux then
2519 -- Else the warning may be needed
2523 Eitem : constant Entity_Id :=
2524 Entity (Name (Item));
2527 -- Warn if we unreferenced flag set and we
2528 -- have not had serious errors. The reason we
2529 -- inhibit the message if there are errors is
2530 -- to prevent false positives from disabling
2533 if not Has_Unreferenced (Eitem)
2534 and then Serious_Errors_Detected = 0
2536 -- Get possible package renaming
2539 Find_Package_Renaming (Munite, Lunit);
2541 -- No warning if either the package or its
2542 -- renaming is used as a generic actual.
2544 if Used_As_Generic_Actual (Eitem)
2548 Used_As_Generic_Actual (Pack))
2553 -- Here we give the warning
2555 Error_Msg_N -- CODEFIX
2556 ("?u?no entities of & are referenced!",
2559 -- Flag renaming of package as well. If
2560 -- the original package has warnings off,
2561 -- we suppress the warning on the renaming
2565 and then not Has_Warnings_Off (Lunit)
2566 and then not Has_Unreferenced (Pack)
2568 Error_Msg_NE -- CODEFIX
2569 ("?u?no entities of& are referenced!",
2570 Unit_Declaration_Node (Pack), Pack);
2578 -- Case of entity being referenced. The reference may
2579 -- come from a limited_with_clause, in which case the
2580 -- limited view of the entity carries the flag.
2582 elsif Referenced_Check_Spec (Ent)
2583 or else Referenced_As_LHS_Check_Spec (Ent)
2584 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2586 (From_Limited_With (Ent)
2587 and then Is_Incomplete_Type (Ent)
2588 and then Present (Non_Limited_View (Ent))
2589 and then Referenced (Non_Limited_View (Ent)))
2591 -- This means that the with is indeed fine, in that
2592 -- it is definitely needed somewhere, and we can
2593 -- quit worrying about this one...
2595 -- Except for one little detail: if either of the
2596 -- flags was set during spec processing, this is
2597 -- where we complain that the with could be moved
2598 -- from the spec. If the spec contains a visible
2599 -- renaming of the package, inhibit warning to move
2600 -- with_clause to body.
2602 if Ekind (Munite) = E_Package_Body then
2604 Find_Package_Renaming
2605 (Spec_Entity (Munite), Lunit);
2610 -- If a renaming is present in the spec do not warn
2611 -- because the body or child unit may depend on it.
2614 and then Renamed_Entity (Pack) = Lunit
2618 elsif Unreferenced_In_Spec (Item) then
2619 Error_Msg_N -- CODEFIX
2620 ("?u?unit& is not referenced in spec!",
2623 elsif No_Entities_Ref_In_Spec (Item) then
2624 Error_Msg_N -- CODEFIX
2625 ("?u?no entities of & are referenced in spec!",
2629 if Ekind (Ent) = E_Package then
2630 Check_Inner_Package (Ent);
2636 if not Is_Visible_Renaming then
2637 Error_Msg_N -- CODEFIX
2638 ("\?u?with clause might be moved to body!",
2644 -- Move to next entity to continue search
2652 -- For a generic package, the only interesting kind of
2653 -- reference is an instantiation, since entities cannot be
2654 -- referenced directly.
2656 elsif Is_Generic_Unit (Lunit) then
2658 -- Unit was never instantiated, set flag for case of spec
2659 -- call, or give warning for normal call.
2661 if not Is_Instantiated (Lunit) then
2662 if Unit = Spec_Unit then
2663 Set_Unreferenced_In_Spec (Item);
2665 Error_Msg_N -- CODEFIX
2666 ("?u?unit& is never instantiated!", Name (Item));
2669 -- If unit was indeed instantiated, make sure that flag is
2670 -- not set showing it was uninstantiated in the spec, and if
2671 -- so, give warning.
2673 elsif Unreferenced_In_Spec (Item) then
2675 ("?u?unit& is not instantiated in spec!", Name (Item));
2676 Error_Msg_N -- CODEFIX
2677 ("\?u?with clause can be moved to body!", Name (Item));
2686 -- Start of processing for Check_Unused_Withs
2689 -- Immediate return if no semantics or warning flag not set
2691 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then
2695 Process_Deferred_References;
2697 -- Flag any unused with clauses. For a subunit, check only the units
2698 -- in its context, not those of the parent, which may be needed by other
2699 -- subunits. We will get the full warnings when we compile the parent,
2700 -- but the following is helpful when compiling a subunit by itself.
2702 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2703 if Current_Sem_Unit = Main_Unit then
2704 Check_One_Unit (Main_Unit);
2710 -- Process specified units
2712 if Spec_Unit = No_Unit then
2714 -- For main call, check all units
2716 for Unit in Main_Unit .. Last_Unit loop
2717 Check_One_Unit (Unit);
2721 -- For call for spec, check only the spec
2723 Check_One_Unit (Spec_Unit);
2725 end Check_Unused_Withs;
2727 ---------------------------------
2728 -- Generic_Package_Spec_Entity --
2729 ---------------------------------
2731 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2735 if Is_Package_Body_Entity (E) then
2741 if S = Standard_Standard then
2744 elsif Ekind (S) = E_Generic_Package then
2747 elsif Ekind (S) = E_Package then
2755 end Generic_Package_Spec_Entity;
2757 ----------------------
2758 -- Goto_Spec_Entity --
2759 ----------------------
2761 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2763 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2764 return Spec_Entity (E);
2768 end Goto_Spec_Entity;
2774 function Has_Junk_Name (E : Entity_Id) return Boolean is
2775 function Match (S : String) return Boolean;
2776 -- Return true if substring S is found in Name_Buffer (1 .. Name_Len)
2782 function Match (S : String) return Boolean is
2783 Slen1 : constant Integer := S'Length - 1;
2786 for J in 1 .. Name_Len - S'Length + 1 loop
2787 if Name_Buffer (J .. J + Slen1) = S then
2795 -- Start of processing for Has_Junk_Name
2798 Get_Unqualified_Decoded_Name_String (Chars (E));
2801 Match ("discard") or else
2802 Match ("dummy") or else
2803 Match ("ignore") or else
2804 Match ("junk") or else
2808 --------------------------------------
2809 -- Has_Pragma_Unmodified_Check_Spec --
2810 --------------------------------------
2812 function Has_Pragma_Unmodified_Check_Spec
2813 (E : Entity_Id) return Boolean
2816 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2818 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2819 -- to mess with Unmodified flags on both body and spec entities.
2820 -- Has_Unmodified has side effects!
2822 return Has_Unmodified (E)
2824 Has_Unmodified (Spec_Entity (E));
2827 return Has_Unmodified (E);
2829 end Has_Pragma_Unmodified_Check_Spec;
2831 ----------------------------------------
2832 -- Has_Pragma_Unreferenced_Check_Spec --
2833 ----------------------------------------
2835 function Has_Pragma_Unreferenced_Check_Spec
2836 (E : Entity_Id) return Boolean
2839 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2841 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2842 -- to mess with flags on both entities.
2844 return Has_Unreferenced (E)
2846 Has_Unreferenced (Spec_Entity (E));
2849 return Has_Unreferenced (E);
2851 end Has_Pragma_Unreferenced_Check_Spec;
2857 procedure Initialize is
2859 Warnings_Off_Pragmas.Init;
2860 Unreferenced_Entities.Init;
2861 In_Out_Warnings.Init;
2864 ---------------------------------------------
2865 -- Is_Attribute_And_Known_Value_Comparison --
2866 ---------------------------------------------
2868 function Is_Attribute_And_Known_Value_Comparison
2869 (Op : Node_Id) return Boolean
2871 Orig_Op : constant Node_Id := Original_Node (Op);
2875 Nkind (Orig_Op) in N_Op_Compare
2876 and then Nkind (Original_Node (Left_Opnd (Orig_Op))) =
2877 N_Attribute_Reference
2878 and then Compile_Time_Known_Value (Right_Opnd (Orig_Op));
2879 end Is_Attribute_And_Known_Value_Comparison;
2881 ------------------------------------
2882 -- Never_Set_In_Source_Check_Spec --
2883 ------------------------------------
2885 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2887 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2888 return Never_Set_In_Source (E)
2890 Never_Set_In_Source (Spec_Entity (E));
2892 return Never_Set_In_Source (E);
2894 end Never_Set_In_Source_Check_Spec;
2896 -------------------------------------
2897 -- Operand_Has_Warnings_Suppressed --
2898 -------------------------------------
2900 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2902 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2903 -- Function used to check one node to see if it is or was originally
2904 -- a reference to an entity for which Warnings are off. If so, Abandon
2905 -- is returned, otherwise OK_Orig is returned to continue the traversal
2906 -- of the original expression.
2908 function Traverse is new Traverse_Func (Check_For_Warnings);
2909 -- Function used to traverse tree looking for warnings
2911 ------------------------
2912 -- Check_For_Warnings --
2913 ------------------------
2915 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2916 R : constant Node_Id := Original_Node (N);
2919 if Nkind (R) in N_Has_Entity
2920 and then Present (Entity (R))
2921 and then Has_Warnings_Off (Entity (R))
2927 end Check_For_Warnings;
2929 -- Start of processing for Operand_Has_Warnings_Suppressed
2932 return Traverse (N) = Abandon;
2934 -- If any exception occurs, then something has gone wrong, and this is
2935 -- only a minor aesthetic issue anyway, so just say we did not find what
2936 -- we are looking for, rather than blow up.
2941 end Operand_Has_Warnings_Suppressed;
2943 -----------------------------------------
2944 -- Output_Non_Modified_In_Out_Warnings --
2945 -----------------------------------------
2947 procedure Output_Non_Modified_In_Out_Warnings is
2949 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2950 -- Given a formal parameter entity E, determines if there is a reason to
2951 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2952 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2953 -- if we have seen the address of the subprogram being taken, or if the
2954 -- subprogram is used as a generic actual (in the latter cases the
2955 -- context may force use of IN OUT, even if the parameter is not
2956 -- modifies for this particular case.
2958 -----------------------
2959 -- No_Warn_On_In_Out --
2960 -----------------------
2962 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2963 S : constant Entity_Id := Scope (E);
2964 SE : constant Entity_Id := Spec_Entity (E);
2967 -- Do not warn if address is taken, since funny business may be going
2968 -- on in treating the parameter indirectly as IN OUT.
2970 if Address_Taken (S)
2971 or else (Present (SE) and then Address_Taken (Scope (SE)))
2975 -- Do not warn if used as a generic actual, since the generic may be
2976 -- what is forcing the use of an "unnecessary" IN OUT.
2978 elsif Used_As_Generic_Actual (S)
2979 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2983 -- Else test warnings off
2985 elsif Warnings_Off_Check_Spec (S) then
2988 -- All tests for suppressing warning failed
2993 end No_Warn_On_In_Out;
2995 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2998 -- Loop through entities for which a warning may be needed
3000 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
3002 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
3005 -- Suppress warning in specific cases (see details in comments for
3006 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
3008 if Has_Pragma_Unmodified_Check_Spec (E1)
3009 or else No_Warn_On_In_Out (E1)
3013 -- Here we generate the warning
3016 -- If -gnatwc is set then output message that we could be IN
3018 if not Is_Trivial_Subprogram (Scope (E1)) then
3019 if Warn_On_Constant then
3021 ("?u?formal parameter & is not modified!", E1);
3023 ("\?u?mode could be IN instead of `IN OUT`!", E1);
3025 -- We do not generate warnings for IN OUT parameters
3026 -- unless we have at least -gnatwu. This is deliberately
3027 -- inconsistent with the treatment of variables, but
3028 -- otherwise we get too many unexpected warnings in
3031 elsif Check_Unreferenced then
3033 ("?u?formal parameter& is read but "
3034 & "never assigned!", E1);
3038 -- Kill any other warnings on this entity, since this is the
3039 -- one that should dominate any other unreferenced warning.
3041 Set_Warnings_Off (E1);
3045 end Output_Non_Modified_In_Out_Warnings;
3047 ----------------------------------------
3048 -- Output_Obsolescent_Entity_Warnings --
3049 ----------------------------------------
3051 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
3052 P : constant Node_Id := Parent (N);
3058 -- Do not output message if we are the scope of standard. This means
3059 -- we have a reference from a context clause from when it is originally
3060 -- processed, and that's too early to tell whether it is an obsolescent
3061 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
3062 -- sure that we have a later call when the scope is available. This test
3063 -- also eliminates all messages for use clauses, which is fine (we do
3064 -- not want messages for use clauses, since they are always redundant
3065 -- with respect to the associated with clause).
3067 if S = Standard_Standard then
3071 -- Do not output message if we are in scope of an obsolescent package
3075 if Is_Obsolescent (S) then
3080 exit when S = Standard_Standard;
3083 -- Here we will output the message
3085 Error_Msg_Sloc := Sloc (E);
3087 -- Case of with clause
3089 if Nkind (P) = N_With_Clause then
3090 if Ekind (E) = E_Package then
3092 ("?j?with of obsolescent package& declared#", N, E);
3093 elsif Ekind (E) = E_Procedure then
3095 ("?j?with of obsolescent procedure& declared#", N, E);
3098 ("??with of obsolescent function& declared#", N, E);
3101 -- If we do not have a with clause, then ignore any reference to an
3102 -- obsolescent package name. We only want to give the one warning of
3103 -- withing the package, not one each time it is used to qualify.
3105 elsif Ekind (E) = E_Package then
3108 -- Procedure call statement
3110 elsif Nkind (P) = N_Procedure_Call_Statement then
3112 ("??call to obsolescent procedure& declared#", N, E);
3116 elsif Nkind (P) = N_Function_Call then
3118 ("??call to obsolescent function& declared#", N, E);
3120 -- Reference to obsolescent type
3122 elsif Is_Type (E) then
3124 ("??reference to obsolescent type& declared#", N, E);
3126 -- Reference to obsolescent component
3128 elsif Ekind_In (E, E_Component, E_Discriminant) then
3130 ("??reference to obsolescent component& declared#", N, E);
3132 -- Reference to obsolescent variable
3134 elsif Ekind (E) = E_Variable then
3136 ("??reference to obsolescent variable& declared#", N, E);
3138 -- Reference to obsolescent constant
3140 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then
3142 ("??reference to obsolescent constant& declared#", N, E);
3144 -- Reference to obsolescent enumeration literal
3146 elsif Ekind (E) = E_Enumeration_Literal then
3148 ("??reference to obsolescent enumeration literal& declared#", N, E);
3150 -- Generic message for any other case we missed
3154 ("??reference to obsolescent entity& declared#", N, E);
3157 -- Output additional warning if present
3159 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
3160 if Obsolescent_Warnings.Table (J).Ent = E then
3161 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
3162 Error_Msg_Strlen := Name_Len;
3163 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
3164 Error_Msg_N ("\\??~", N);
3168 end Output_Obsolescent_Entity_Warnings;
3170 ----------------------------------
3171 -- Output_Unreferenced_Messages --
3172 ----------------------------------
3174 procedure Output_Unreferenced_Messages is
3176 for J in Unreferenced_Entities.First .. Unreferenced_Entities.Last loop
3177 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
3179 end Output_Unreferenced_Messages;
3181 -----------------------------------------
3182 -- Output_Unused_Warnings_Off_Warnings --
3183 -----------------------------------------
3185 procedure Output_Unused_Warnings_Off_Warnings is
3187 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
3189 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
3190 N : Node_Id renames Wentry.N;
3191 E : Node_Id renames Wentry.E;
3194 -- Turn off Warnings_Off, or we won't get the warning
3196 Set_Warnings_Off (E, False);
3198 -- Nothing to do if pragma was used to suppress a general warning
3200 if Warnings_Off_Used (E) then
3203 -- If pragma was used both in unmodified and unreferenced contexts
3204 -- then that's as good as the general case, no warning.
3206 elsif Warnings_Off_Used_Unmodified (E)
3208 Warnings_Off_Used_Unreferenced (E)
3212 -- Used only in context where Unmodified would have worked
3214 elsif Warnings_Off_Used_Unmodified (E) then
3216 ("?W?could use Unmodified instead of "
3217 & "Warnings Off for &", Pragma_Identifier (N), E);
3219 -- Used only in context where Unreferenced would have worked
3221 elsif Warnings_Off_Used_Unreferenced (E) then
3223 ("?W?could use Unreferenced instead of "
3224 & "Warnings Off for &", Pragma_Identifier (N), E);
3230 ("?W?pragma Warnings Off for & unused, "
3231 & "could be omitted", N, E);
3235 end Output_Unused_Warnings_Off_Warnings;
3237 ---------------------------
3238 -- Referenced_Check_Spec --
3239 ---------------------------
3241 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3243 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3244 return Referenced (E) or else Referenced (Spec_Entity (E));
3246 return Referenced (E);
3248 end Referenced_Check_Spec;
3250 ----------------------------------
3251 -- Referenced_As_LHS_Check_Spec --
3252 ----------------------------------
3254 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3256 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3257 return Referenced_As_LHS (E)
3258 or else Referenced_As_LHS (Spec_Entity (E));
3260 return Referenced_As_LHS (E);
3262 end Referenced_As_LHS_Check_Spec;
3264 --------------------------------------------
3265 -- Referenced_As_Out_Parameter_Check_Spec --
3266 --------------------------------------------
3268 function Referenced_As_Out_Parameter_Check_Spec
3269 (E : Entity_Id) return Boolean
3272 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3273 return Referenced_As_Out_Parameter (E)
3274 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3276 return Referenced_As_Out_Parameter (E);
3278 end Referenced_As_Out_Parameter_Check_Spec;
3280 --------------------------------------
3281 -- Warn_On_Constant_Valid_Condition --
3282 --------------------------------------
3284 procedure Warn_On_Constant_Valid_Condition (Op : Node_Id) is
3285 Left : constant Node_Id := Left_Opnd (Op);
3286 Right : constant Node_Id := Right_Opnd (Op);
3288 True_Result : Boolean;
3289 False_Result : Boolean;
3292 -- Determine the potential outcome of the comparison assuming that the
3293 -- scalar operands are valid.
3295 if Constant_Condition_Warnings
3296 and then Comes_From_Source (Original_Node (Op))
3297 and then Is_Scalar_Type (Etype (Left))
3298 and then Is_Scalar_Type (Etype (Right))
3300 -- Do not consider instances because the check was already performed
3303 and then not In_Instance
3305 -- Do not consider comparisons between two static expressions such as
3306 -- constants or literals because those values cannot be invalidated.
3308 and then not (Is_Static_Expression (Left)
3309 and then Is_Static_Expression (Right))
3311 -- Do not consider comparison between an attribute reference and a
3312 -- compile-time known value since this is most likely a conditional
3315 and then not Is_Attribute_And_Known_Value_Comparison (Op)
3317 -- Do not consider internal files to allow for various assertions and
3318 -- safeguards within our runtime.
3320 and then not In_Internal_Unit (Op)
3324 Assume_Valid => True,
3325 True_Result => True_Result,
3326 False_Result => False_Result);
3328 -- Warn on a possible evaluation to False / True in the presence of
3333 ("condition can only be False if invalid values present??", Op);
3335 elsif False_Result then
3337 ("condition can only be True if invalid values present??", Op);
3340 end Warn_On_Constant_Valid_Condition;
3342 -----------------------------
3343 -- Warn_On_Known_Condition --
3344 -----------------------------
3346 procedure Warn_On_Known_Condition (C : Node_Id) is
3347 Test_Result : Boolean := False;
3348 -- Force initialization to facilitate static analysis
3350 function Is_Known_Branch return Boolean;
3351 -- If the type of the condition is Boolean, the constant value of the
3352 -- condition is a boolean literal. If the type is a derived boolean
3353 -- type, the constant is wrapped in a type conversion of the derived
3354 -- literal. If the value of the condition is not a literal, no warnings
3355 -- can be produced. This function returns True if the result can be
3356 -- determined, and Test_Result is set True/False accordingly. Otherwise
3357 -- False is returned, and Test_Result is unchanged.
3359 procedure Track (N : Node_Id; Loc : Node_Id);
3360 -- Adds continuation warning(s) pointing to reason (assignment or test)
3361 -- for the operand of the conditional having a known value (or at least
3362 -- enough is known about the value to issue the warning). N is the node
3363 -- which is judged to have a known value. Loc is the warning location.
3365 ---------------------
3366 -- Is_Known_Branch --
3367 ---------------------
3369 function Is_Known_Branch return Boolean is
3371 if Etype (C) = Standard_Boolean
3372 and then Is_Entity_Name (C)
3374 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3376 Test_Result := Entity (C) = Standard_True;
3379 elsif Is_Boolean_Type (Etype (C))
3380 and then Nkind (C) = N_Unchecked_Type_Conversion
3381 and then Is_Entity_Name (Expression (C))
3382 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3385 Chars (Entity (Expression (C))) = Chars (Standard_True);
3391 end Is_Known_Branch;
3397 procedure Track (N : Node_Id; Loc : Node_Id) is
3398 Nod : constant Node_Id := Original_Node (N);
3401 if Nkind (Nod) in N_Op_Compare then
3402 Track (Left_Opnd (Nod), Loc);
3403 Track (Right_Opnd (Nod), Loc);
3405 elsif Is_Entity_Name (Nod) and then Is_Object (Entity (Nod)) then
3407 CV : constant Node_Id := Current_Value (Entity (Nod));
3410 if Present (CV) then
3411 Error_Msg_Sloc := Sloc (CV);
3413 if Nkind (CV) not in N_Subexpr then
3414 Error_Msg_N ("\\??(see test #)", Loc);
3416 elsif Nkind (Parent (CV)) =
3417 N_Case_Statement_Alternative
3419 Error_Msg_N ("\\??(see case alternative #)", Loc);
3422 Error_Msg_N ("\\??(see assignment #)", Loc);
3431 Orig : constant Node_Id := Original_Node (C);
3434 -- Start of processing for Warn_On_Known_Condition
3437 -- Adjust SCO condition if from source
3440 and then Comes_From_Source (Orig)
3441 and then Is_Known_Branch
3447 Atrue := Test_Result;
3449 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3453 Set_SCO_Condition (Orig, Atrue);
3457 -- Argument replacement in an inlined body can make conditions static.
3458 -- Do not emit warnings in this case.
3460 if In_Inlined_Body then
3464 if Constant_Condition_Warnings
3465 and then Is_Known_Branch
3466 and then Comes_From_Source (Orig)
3467 and then not In_Instance
3469 -- Don't warn if comparison of result of attribute against a constant
3470 -- value, since this is likely legitimate conditional compilation.
3472 if Is_Attribute_And_Known_Value_Comparison (C) then
3476 -- See if this is in a statement or a declaration
3480 -- If tree is not attached, do not issue warning (this is very
3481 -- peculiar, and probably arises from some other error condition).
3486 -- If we are in a declaration, then no warning, since in practice
3487 -- conditionals in declarations are used for intended tests which
3488 -- may be known at compile time, e.g. things like
3490 -- x : constant Integer := 2 + (Word'Size = 32);
3492 -- And a warning is annoying in such cases
3494 elsif Nkind (P) in N_Declaration
3496 Nkind (P) in N_Later_Decl_Item
3500 -- Don't warn in assert or check pragma, since presumably tests in
3501 -- such a context are very definitely intended, and might well be
3502 -- known at compile time. Note that we have to test the original
3503 -- node, since assert pragmas get rewritten at analysis time.
3505 elsif Nkind (Original_Node (P)) = N_Pragma
3506 and then Nam_In (Pragma_Name_Unmapped (Original_Node (P)),
3507 Name_Assert, Name_Check)
3512 exit when Is_Statement (P);
3516 -- Here we issue the warning unless some sub-operand has warnings
3517 -- set off, in which case we suppress the warning for the node. If
3518 -- the original expression is an inequality, it has been expanded
3519 -- into a negation, and the value of the original expression is the
3520 -- negation of the equality. If the expression is an entity that
3521 -- appears within a negation, it is clearer to flag the negation
3522 -- itself, and report on its constant value.
3524 if not Operand_Has_Warnings_Suppressed (C) then
3526 True_Branch : Boolean := Test_Result;
3527 Cond : Node_Id := C;
3530 if Present (Parent (C))
3531 and then Nkind (Parent (C)) = N_Op_Not
3533 True_Branch := not True_Branch;
3537 -- Condition always True
3540 if Is_Entity_Name (Original_Node (C))
3541 and then Nkind (Cond) /= N_Op_Not
3544 ("object & is always True at this point?c?",
3545 Cond, Original_Node (C));
3546 Track (Original_Node (C), Cond);
3549 Error_Msg_N ("condition is always True?c?", Cond);
3553 -- Condition always False
3556 if Is_Entity_Name (Original_Node (C))
3557 and then Nkind (Cond) /= N_Op_Not
3560 ("object & is always False at this point?c?",
3561 Cond, Original_Node (C));
3562 Track (Original_Node (C), Cond);
3565 Error_Msg_N ("condition is always False?c?", Cond);
3572 end Warn_On_Known_Condition;
3574 ---------------------------------------
3575 -- Warn_On_Modified_As_Out_Parameter --
3576 ---------------------------------------
3578 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3581 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3582 or else Warn_On_All_Unread_Out_Parameters;
3583 end Warn_On_Modified_As_Out_Parameter;
3585 ---------------------------------
3586 -- Warn_On_Overlapping_Actuals --
3587 ---------------------------------
3589 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3590 function Is_Covered_Formal (Formal : Node_Id) return Boolean;
3591 -- Return True if Formal is covered by the rule
3593 function Refer_Same_Object
3595 Act2 : Node_Id) return Boolean;
3596 -- Two names are known to refer to the same object if the two names
3597 -- are known to denote the same object; or one of the names is a
3598 -- selected_component, indexed_component, or slice and its prefix is
3599 -- known to refer to the same object as the other name; or one of the
3600 -- two names statically denotes a renaming declaration whose renamed
3601 -- object_name is known to refer to the same object as the other name
3602 -- (RM 6.4.1(6.11/3))
3604 -----------------------
3605 -- Is_Covered_Formal --
3606 -----------------------
3608 function Is_Covered_Formal (Formal : Node_Id) return Boolean is
3611 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter)
3612 and then (Is_Elementary_Type (Etype (Formal))
3613 or else Is_Record_Type (Etype (Formal))
3614 or else Is_Array_Type (Etype (Formal)));
3615 end Is_Covered_Formal;
3617 -----------------------
3618 -- Refer_Same_Object --
3619 -----------------------
3621 function Refer_Same_Object
3623 Act2 : Node_Id) return Boolean
3627 Denotes_Same_Object (Act1, Act2)
3628 or else Denotes_Same_Prefix (Act1, Act2);
3629 end Refer_Same_Object;
3637 Warn_Only : Boolean;
3638 -- GNAT warns on overlapping in-out parameters even when there are no
3639 -- two in-out parameters of an elementary type, as stated in
3642 -- Start of processing for Warn_On_Overlapping_Actuals
3646 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then
3650 -- The call is illegal only if there are at least two in-out parameters
3651 -- of the same elementary type.
3654 Form1 := First_Formal (Subp);
3655 while Present (Form1) loop
3656 Form2 := Next_Formal (Form1);
3657 while Present (Form2) loop
3658 if Is_Elementary_Type (Etype (Form1))
3659 and then Is_Elementary_Type (Etype (Form2))
3660 and then Ekind (Form1) /= E_In_Parameter
3661 and then Ekind (Form2) /= E_In_Parameter
3667 Next_Formal (Form2);
3670 Next_Formal (Form1);
3673 -- Exclude calls rewritten as enumeration literals
3675 if Nkind (N) not in N_Subprogram_Call
3676 and then Nkind (N) /= N_Entry_Call_Statement
3681 -- If a call C has two or more parameters of mode in out or out that are
3682 -- of an elementary type, then the call is legal only if for each name
3683 -- N that is passed as a parameter of mode in out or out to the call C,
3684 -- there is no other name among the other parameters of mode in out or
3685 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3687 -- If appropriate warning switch is set, we also report warnings on
3688 -- overlapping parameters that are record types or array types.
3690 Form1 := First_Formal (Subp);
3691 Act1 := First_Actual (N);
3692 while Present (Form1) and then Present (Act1) loop
3693 if Is_Covered_Formal (Form1) then
3694 Form2 := First_Formal (Subp);
3695 Act2 := First_Actual (N);
3696 while Present (Form2) and then Present (Act2) loop
3698 and then Is_Covered_Formal (Form2)
3699 and then Refer_Same_Object (Act1, Act2)
3701 -- Guard against previous errors
3704 or else No (Etype (Act1))
3705 or else No (Etype (Act2))
3709 -- If the actual is a function call in prefix notation,
3710 -- there is no real overlap.
3712 elsif Nkind (Act2) = N_Function_Call then
3715 -- If type is not by-copy, assume that aliasing is intended
3718 Present (Underlying_Type (Etype (Form1)))
3720 (Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3722 Convention (Underlying_Type (Etype (Form1))) =
3723 Convention_Ada_Pass_By_Reference)
3727 -- Under Ada 2012 we only report warnings on overlapping
3728 -- arrays and record types if switch is set.
3730 elsif Ada_Version >= Ada_2012
3731 and then not Is_Elementary_Type (Etype (Form1))
3732 and then not Warn_On_Overlap
3736 -- Here we may need to issue overlap message
3741 -- Overlap checking is an error only in Ada 2012. For
3742 -- earlier versions of Ada, this is a warning.
3744 Ada_Version < Ada_2012
3746 -- Overlap is only illegal in Ada 2012 in the case of
3747 -- elementary types (passed by copy). For other types,
3748 -- we always have a warning in all Ada versions.
3750 or else not Is_Elementary_Type (Etype (Form1))
3752 -- debug flag -gnatd.E changes the error to a warning
3753 -- even in Ada 2012 mode.
3755 or else Error_To_Warning
3763 -- Find matching actual
3765 Act := First_Actual (N);
3766 Form := First_Formal (Subp);
3767 while Act /= Act2 loop
3772 if Is_Elementary_Type (Etype (Act1))
3773 and then Ekind (Form2) = E_In_Parameter
3775 null; -- No real aliasing
3777 elsif Is_Elementary_Type (Etype (Act2))
3778 and then Ekind (Form2) = E_In_Parameter
3782 -- If the call was written in prefix notation, and
3783 -- thus its prefix before rewriting was a selected
3784 -- component, count only visible actuals in the call.
3786 elsif Is_Entity_Name (First_Actual (N))
3787 and then Nkind (Original_Node (N)) = Nkind (N)
3788 and then Nkind (Name (Original_Node (N))) =
3789 N_Selected_Component
3791 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3793 Entity (Prefix (Name (Original_Node (N)))) =
3794 Entity (First_Actual (N))
3796 if Act1 = First_Actual (N) then
3798 ("<<`IN OUT` prefix overlaps with "
3799 & "actual for&", Act1, Form);
3802 -- For greater clarity, give name of formal
3804 Error_Msg_Node_2 := Form;
3806 ("<<writable actual for & overlaps with "
3807 & "actual for&", Act1, Form);
3811 -- For greater clarity, give name of formal
3813 Error_Msg_Node_2 := Form;
3815 -- This is one of the messages
3818 ("<<writable actual for & overlaps with "
3819 & "actual for&", Act1, Form1);
3827 Next_Formal (Form2);
3832 Next_Formal (Form1);
3835 end Warn_On_Overlapping_Actuals;
3837 ------------------------------
3838 -- Warn_On_Suspicious_Index --
3839 ------------------------------
3841 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3844 -- Set to lower bound for a suspicious type
3847 -- Entity for array reference
3852 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3853 -- Tests to see if Typ is a type for which we may have a suspicious
3854 -- index, namely an unconstrained array type, whose lower bound is
3855 -- either zero or one. If so, True is returned, and Low_Bound is set
3856 -- to this lower bound. If not, False is returned, and Low_Bound is
3857 -- undefined on return.
3859 -- For now, we limit this to standard string types, so any other
3860 -- unconstrained types return False. We may change our minds on this
3861 -- later on, but strings seem the most important case.
3863 procedure Test_Suspicious_Index;
3864 -- Test if index is of suspicious type and if so, generate warning
3866 ------------------------
3867 -- Is_Suspicious_Type --
3868 ------------------------
3870 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3874 if Is_Array_Type (Typ)
3875 and then not Is_Constrained (Typ)
3876 and then Number_Dimensions (Typ) = 1
3877 and then Is_Standard_String_Type (Typ)
3878 and then not Has_Warnings_Off (Typ)
3880 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3882 if Compile_Time_Known_Value (LB) then
3883 Low_Bound := Expr_Value (LB);
3884 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3889 end Is_Suspicious_Type;
3891 ---------------------------
3892 -- Test_Suspicious_Index --
3893 ---------------------------
3895 procedure Test_Suspicious_Index is
3897 function Length_Reference (N : Node_Id) return Boolean;
3898 -- Check if node N is of the form Name'Length
3901 -- Generate first warning line
3903 procedure Warn_On_Index_Below_Lower_Bound;
3904 -- Generate a warning on indexing the array with a literal value
3905 -- below the lower bound of the index type.
3907 procedure Warn_On_Literal_Index;
3908 -- Generate a warning on indexing the array with a literal value
3910 ----------------------
3911 -- Length_Reference --
3912 ----------------------
3914 function Length_Reference (N : Node_Id) return Boolean is
3915 R : constant Node_Id := Original_Node (N);
3918 Nkind (R) = N_Attribute_Reference
3919 and then Attribute_Name (R) = Name_Length
3920 and then Is_Entity_Name (Prefix (R))
3921 and then Entity (Prefix (R)) = Ent;
3922 end Length_Reference;
3930 Error_Msg_Uint_1 := Low_Bound;
3931 Error_Msg_FE -- CODEFIX
3932 ("?w?index for& may assume lower bound of^", X, Ent);
3935 -------------------------------------
3936 -- Warn_On_Index_Below_Lower_Bound --
3937 -------------------------------------
3939 procedure Warn_On_Index_Below_Lower_Bound is
3941 if Is_Standard_String_Type (Typ) then
3943 (Compile_Time_Constraint_Error
3945 Msg => "?w?string index should be positive"));
3948 (Compile_Time_Constraint_Error
3950 Msg => "?w?index out of the allowed range"));
3952 end Warn_On_Index_Below_Lower_Bound;
3954 ---------------------------
3955 -- Warn_On_Literal_Index --
3956 ---------------------------
3958 procedure Warn_On_Literal_Index is
3962 -- Case where original form of subscript is an integer literal
3964 if Nkind (Original_Node (X)) = N_Integer_Literal then
3965 if Intval (X) = Low_Bound then
3966 Error_Msg_FE -- CODEFIX
3967 ("\?w?suggested replacement: `&''First`", X, Ent);
3969 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3970 Error_Msg_FE -- CODEFIX
3971 ("\?w?suggested replacement: `&''First + ^`", X, Ent);
3975 -- Case where original form of subscript is more complex
3978 -- Build string X'First - 1 + expression where the expression
3979 -- is the original subscript. If the expression starts with "1
3980 -- + ", then the "- 1 + 1" is elided.
3982 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3983 Error_Msg_Strlen := 13;
3986 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3987 Tref : constant Source_Buffer_Ptr :=
3988 Source_Text (Get_Source_File_Index (Sref));
3989 -- Tref (Sref) is used to scan the subscript
3992 -- Parentheses counter when scanning subscript
3995 -- Tref (Sref) points to start of subscript
3997 -- Elide - 1 if subscript starts with 1 +
3999 if Tref (Sref .. Sref + 2) = "1 +" then
4000 Error_Msg_Strlen := Error_Msg_Strlen - 6;
4003 elsif Tref (Sref .. Sref + 1) = "1+" then
4004 Error_Msg_Strlen := Error_Msg_Strlen - 6;
4008 -- Now we will copy the subscript to the string buffer
4012 -- Count parens, exit if terminating right paren. Note
4013 -- check to ignore paren appearing as character literal.
4015 if Tref (Sref + 1) = '''
4017 Tref (Sref - 1) = '''
4021 if Tref (Sref) = '(' then
4023 elsif Tref (Sref) = ')' then
4029 -- Done if terminating double dot (slice case)
4032 and then (Tref (Sref .. Sref + 1) = ".."
4034 Tref (Sref .. Sref + 2) = " ..");
4036 -- Quit if we have hit EOF character, something wrong
4038 if Tref (Sref) = EOF then
4042 -- String literals are too much of a pain to handle
4044 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
4048 -- If we have a 'Range reference, then this is a case
4049 -- where we cannot easily give a replacement. Don't try.
4051 if Tref (Sref .. Sref + 4) = "range"
4052 and then Tref (Sref - 1) < 'A'
4053 and then Tref (Sref + 5) < 'A'
4058 -- Else store next character
4060 Error_Msg_Strlen := Error_Msg_Strlen + 1;
4061 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
4064 -- If we get more than 40 characters then the expression
4065 -- is too long to copy, or something has gone wrong. In
4066 -- either case, just skip the attempt at a suggested fix.
4068 if Error_Msg_Strlen > 40 then
4074 -- Replacement subscript is now in string buffer
4076 Error_Msg_FE -- CODEFIX
4077 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent);
4079 end Warn_On_Literal_Index;
4081 -- Start of processing for Test_Suspicious_Index
4084 -- Nothing to do if subscript does not come from source (we don't
4085 -- want to give garbage warnings on compiler expanded code, e.g. the
4086 -- loops generated for slice assignments. Such junk warnings would
4087 -- be placed on source constructs with no subscript in sight).
4089 if not Comes_From_Source (Original_Node (X)) then
4093 -- Case where subscript is a constant integer
4095 if Nkind (X) = N_Integer_Literal then
4097 -- Case where subscript is lower than the lowest possible bound.
4098 -- This might be the case for example when programmers try to
4099 -- access a string at index 0, as they are used to in other
4100 -- programming languages like C.
4102 if Intval (X) < Low_Bound then
4103 Warn_On_Index_Below_Lower_Bound;
4105 Warn_On_Literal_Index;
4108 -- Case where subscript is of the form X'Length
4110 elsif Length_Reference (X) then
4112 Error_Msg_Node_2 := Ent;
4114 ("\?w?suggest replacement of `&''Length` by `&''Last`",
4117 -- Case where subscript is of the form X'Length - expression
4119 elsif Nkind (X) = N_Op_Subtract
4120 and then Length_Reference (Left_Opnd (X))
4123 Error_Msg_Node_2 := Ent;
4125 ("\?w?suggest replacement of `&''Length` by `&''Last`",
4126 Left_Opnd (X), Ent);
4128 end Test_Suspicious_Index;
4130 -- Start of processing for Warn_On_Suspicious_Index
4133 -- Only process if warnings activated
4135 if Warn_On_Assumed_Low_Bound then
4137 -- Test if array is simple entity name
4139 if Is_Entity_Name (Name) then
4141 -- Test if array is parameter of unconstrained string type
4143 Ent := Entity (Name);
4147 and then Is_Suspicious_Type (Typ)
4148 and then not Low_Bound_Tested (Ent)
4150 Test_Suspicious_Index;
4154 end Warn_On_Suspicious_Index;
4156 -------------------------------
4157 -- Warn_On_Suspicious_Update --
4158 -------------------------------
4160 procedure Warn_On_Suspicious_Update (N : Node_Id) is
4161 Par : constant Node_Id := Parent (N);
4165 -- Only process if warnings activated
4167 if Warn_On_Suspicious_Contract then
4168 if Nkind_In (Par, N_Op_Eq, N_Op_Ne) then
4169 if N = Left_Opnd (Par) then
4170 Arg := Right_Opnd (Par);
4172 Arg := Left_Opnd (Par);
4175 if Same_Object (Prefix (N), Arg) then
4176 if Nkind (Par) = N_Op_Eq then
4178 ("suspicious equality test with modified version of "
4179 & "same object?T?", Par);
4182 ("suspicious inequality test with modified version of "
4183 & "same object?T?", Par);
4188 end Warn_On_Suspicious_Update;
4190 --------------------------------------
4191 -- Warn_On_Unassigned_Out_Parameter --
4192 --------------------------------------
4194 procedure Warn_On_Unassigned_Out_Parameter
4195 (Return_Node : Node_Id;
4196 Scope_Id : Entity_Id)
4202 -- Ignore if procedure or return statement does not come from source
4204 if not Comes_From_Source (Scope_Id)
4205 or else not Comes_From_Source (Return_Node)
4210 -- Loop through formals
4212 Form := First_Formal (Scope_Id);
4213 while Present (Form) loop
4215 -- We are only interested in OUT parameters that come from source
4216 -- and are never set in the source, and furthermore only in scalars
4217 -- since non-scalars generate too many false positives.
4219 if Ekind (Form) = E_Out_Parameter
4220 and then Never_Set_In_Source_Check_Spec (Form)
4221 and then Is_Scalar_Type (Etype (Form))
4222 and then not Present (Unset_Reference (Form))
4224 -- Before we issue the warning, an add ad hoc defence against the
4225 -- most common case of false positives with this warning which is
4226 -- the case where there is a Boolean OUT parameter that has been
4227 -- set, and whose meaning is "ignore the values of the other
4228 -- parameters". We can't of course reliably tell this case at
4229 -- compile time, but the following test kills a lot of false
4230 -- positives, without generating a significant number of false
4231 -- negatives (missed real warnings).
4233 Form2 := First_Formal (Scope_Id);
4234 while Present (Form2) loop
4235 if Ekind (Form2) = E_Out_Parameter
4236 and then Root_Type (Etype (Form2)) = Standard_Boolean
4237 and then not Never_Set_In_Source_Check_Spec (Form2)
4242 Next_Formal (Form2);
4245 -- Here all conditions are met, record possible unset reference
4247 Set_Unset_Reference (Form, Return_Node);
4252 end Warn_On_Unassigned_Out_Parameter;
4254 ---------------------------------
4255 -- Warn_On_Unreferenced_Entity --
4256 ---------------------------------
4258 procedure Warn_On_Unreferenced_Entity
4259 (Spec_E : Entity_Id;
4260 Body_E : Entity_Id := Empty)
4262 E : Entity_Id := Spec_E;
4265 if not Referenced_Check_Spec (E)
4266 and then not Has_Pragma_Unreferenced_Check_Spec (E)
4267 and then not Warnings_Off_Check_Spec (E)
4268 and then not Has_Junk_Name (Spec_E)
4269 and then not Is_Exported (Spec_E)
4274 -- Case of variable that is assigned but not read. We suppress
4275 -- the message if the variable is volatile, has an address
4276 -- clause, is aliased, or is a renaming, or is imported.
4278 if Referenced_As_LHS_Check_Spec (E)
4279 and then No (Address_Clause (E))
4280 and then not Is_Volatile (E)
4282 if Warn_On_Modified_Unread
4283 and then not Is_Imported (E)
4284 and then not Is_Aliased (E)
4285 and then No (Renamed_Object (E))
4287 if not Has_Pragma_Unmodified_Check_Spec (E) then
4288 Error_Msg_N -- CODEFIX
4289 ("?m?variable & is assigned but never read!", E);
4292 Set_Last_Assignment (E, Empty);
4295 -- Normal case of neither assigned nor read (exclude variables
4296 -- referenced as out parameters, since we already generated
4297 -- appropriate warnings at the call point in this case).
4299 elsif not Referenced_As_Out_Parameter (E) then
4301 -- We suppress the message for types for which a valid
4302 -- pragma Unreferenced_Objects has been given, otherwise
4303 -- we go ahead and give the message.
4305 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
4307 -- Distinguish renamed case in message
4309 if Present (Renamed_Object (E))
4310 and then Comes_From_Source (Renamed_Object (E))
4312 Error_Msg_N -- CODEFIX
4313 ("?u?renamed variable & is not referenced!", E);
4315 Error_Msg_N -- CODEFIX
4316 ("?u?variable & is not referenced!", E);
4322 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
4323 if Present (Renamed_Object (E))
4324 and then Comes_From_Source (Renamed_Object (E))
4326 Error_Msg_N -- CODEFIX
4327 ("?u?renamed constant & is not referenced!", E);
4329 Error_Msg_N -- CODEFIX
4330 ("?u?constant & is not referenced!", E);
4334 when E_In_Out_Parameter
4337 -- Do not emit message for formals of a renaming, because they
4338 -- are never referenced explicitly.
4340 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /=
4341 N_Subprogram_Renaming_Declaration
4343 -- Suppress this message for an IN OUT parameter of a
4344 -- non-scalar type, since it is normal to have only an
4345 -- assignment in such a case.
4347 if Ekind (E) = E_In_Parameter
4348 or else not Referenced_As_LHS_Check_Spec (E)
4349 or else Is_Scalar_Type (Etype (E))
4351 if Present (Body_E) then
4355 if not Is_Trivial_Subprogram (Scope (E)) then
4356 Error_Msg_NE -- CODEFIX
4357 ("?u?formal parameter & is not referenced!",
4363 when E_Out_Parameter =>
4366 when E_Discriminant =>
4367 Error_Msg_N ("?u?discriminant & is not referenced!", E);
4369 when E_Named_Integer
4372 Error_Msg_N -- CODEFIX
4373 ("?u?named number & is not referenced!", E);
4375 when Formal_Object_Kind =>
4376 Error_Msg_N -- CODEFIX
4377 ("?u?formal object & is not referenced!", E);
4379 when E_Enumeration_Literal =>
4380 Error_Msg_N -- CODEFIX
4381 ("?u?literal & is not referenced!", E);
4384 Error_Msg_N -- CODEFIX
4385 ("?u?function & is not referenced!", E);
4388 Error_Msg_N -- CODEFIX
4389 ("?u?procedure & is not referenced!", E);
4392 Error_Msg_N -- CODEFIX
4393 ("?u?package & is not referenced!", E);
4396 Error_Msg_N -- CODEFIX
4397 ("?u?exception & is not referenced!", E);
4400 Error_Msg_N -- CODEFIX
4401 ("?u?label & is not referenced!", E);
4403 when E_Generic_Procedure =>
4404 Error_Msg_N -- CODEFIX
4405 ("?u?generic procedure & is never instantiated!", E);
4407 when E_Generic_Function =>
4408 Error_Msg_N -- CODEFIX
4409 ("?u?generic function & is never instantiated!", E);
4412 Error_Msg_N -- CODEFIX
4413 ("?u?type & is not referenced!", E);
4416 Error_Msg_N -- CODEFIX
4417 ("?u?& is not referenced!", E);
4420 -- Kill warnings on the entity on which the message has been posted
4421 -- (nothing is posted on out parameters because back end might be
4422 -- able to uncover an uninitialized path, and warn accordingly).
4424 if Ekind (E) /= E_Out_Parameter then
4425 Set_Warnings_Off (E);
4428 end Warn_On_Unreferenced_Entity;
4430 --------------------------------
4431 -- Warn_On_Useless_Assignment --
4432 --------------------------------
4434 procedure Warn_On_Useless_Assignment
4436 N : Node_Id := Empty)
4441 function Check_Ref (N : Node_Id) return Traverse_Result;
4442 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4443 -- the entity in question is found.
4445 function Test_No_Refs is new Traverse_Func (Check_Ref);
4451 function Check_Ref (N : Node_Id) return Traverse_Result is
4453 -- Check reference to our identifier. We use name equality here
4454 -- because the exception handlers have not yet been analyzed. This
4455 -- is not quite right, but it really does not matter that we fail
4456 -- to output the warning in some obscure cases of name clashes.
4458 if Nkind (N) = N_Identifier and then Chars (N) = Chars (Ent) then
4465 -- Start of processing for Warn_On_Useless_Assignment
4468 -- Check if this is a case we want to warn on, a scalar or access
4469 -- variable with the last assignment field set, with warnings enabled,
4470 -- and which is not imported or exported. We also check that it is OK
4471 -- to capture the value. We are not going to capture any value, but
4472 -- the warning message depends on the same kind of conditions.
4474 if Is_Assignable (Ent)
4475 and then not Is_Return_Object (Ent)
4476 and then Present (Last_Assignment (Ent))
4477 and then not Is_Imported (Ent)
4478 and then not Is_Exported (Ent)
4479 and then Safe_To_Capture_Value (N, Ent)
4480 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
4481 and then not Has_Junk_Name (Ent)
4483 -- Before we issue the message, check covering exception handlers.
4484 -- Search up tree for enclosing statement sequences and handlers.
4486 P := Parent (Last_Assignment (Ent));
4487 while Present (P) loop
4489 -- Something is really wrong if we don't find a handled statement
4490 -- sequence, so just suppress the warning.
4493 Set_Last_Assignment (Ent, Empty);
4496 -- When we hit a package/subprogram body, issue warning and exit
4498 elsif Nkind_In (P, N_Entry_Body,
4503 -- Case of assigned value never referenced
4507 LA : constant Node_Id := Last_Assignment (Ent);
4510 -- Don't give this for OUT and IN OUT formals, since
4511 -- clearly caller may reference the assigned value. Also
4512 -- never give such warnings for internal variables. In
4513 -- either case, word the warning in a conditional way,
4514 -- because in the case of a component of a controlled
4515 -- type, the assigned value might be referenced in the
4516 -- Finalize operation, so we can't make a definitive
4517 -- statement that it's never referenced.
4519 if Ekind (Ent) = E_Variable
4520 and then not Is_Internal_Name (Chars (Ent))
4522 -- Give appropriate message, distinguishing between
4523 -- assignment statements and out parameters.
4525 if Nkind_In (Parent (LA), N_Parameter_Association,
4526 N_Procedure_Call_Statement)
4529 ("?m?& modified by call, but value might not be "
4530 & "referenced", LA, Ent);
4533 Error_Msg_NE -- CODEFIX
4534 ("?m?possibly useless assignment to&, value "
4535 & "might not be referenced!", LA, Ent);
4540 -- Case of assigned value overwritten
4544 LA : constant Node_Id := Last_Assignment (Ent);
4547 Error_Msg_Sloc := Sloc (N);
4549 -- Give appropriate message, distinguishing between
4550 -- assignment statements and out parameters.
4552 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4553 N_Parameter_Association)
4556 ("?m?& modified by call, but value overwritten #!",
4559 Error_Msg_NE -- CODEFIX
4560 ("?m?useless assignment to&, value overwritten #!",
4566 -- Clear last assignment indication and we are done
4568 Set_Last_Assignment (Ent, Empty);
4571 -- Enclosing handled sequence of statements
4573 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4575 -- Check exception handlers present
4577 if Present (Exception_Handlers (P)) then
4579 -- If we are not at the top level, we regard an inner
4580 -- exception handler as a decisive indicator that we should
4581 -- not generate the warning, since the variable in question
4582 -- may be accessed after an exception in the outer block.
4584 if not Nkind_In (Parent (P), N_Entry_Body,
4589 Set_Last_Assignment (Ent, Empty);
4592 -- Otherwise we are at the outer level. An exception
4593 -- handler is significant only if it references the
4594 -- variable in question, or if the entity in question
4595 -- is an OUT or IN OUT parameter, in which case
4596 -- the caller can reference it after the exception
4597 -- handler completes.
4600 if Is_Formal (Ent) then
4601 Set_Last_Assignment (Ent, Empty);
4605 X := First (Exception_Handlers (P));
4606 while Present (X) loop
4607 if Test_No_Refs (X) = Abandon then
4608 Set_Last_Assignment (Ent, Empty);
4622 end Warn_On_Useless_Assignment;
4624 ---------------------------------
4625 -- Warn_On_Useless_Assignments --
4626 ---------------------------------
4628 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4632 Process_Deferred_References;
4634 if Warn_On_Modified_Unread
4635 and then In_Extended_Main_Source_Unit (E)
4637 Ent := First_Entity (E);
4638 while Present (Ent) loop
4639 Warn_On_Useless_Assignment (Ent);
4643 end Warn_On_Useless_Assignments;
4645 -----------------------------
4646 -- Warnings_Off_Check_Spec --
4647 -----------------------------
4649 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4651 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4653 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4654 -- to mess with flags on both entities.
4656 return Has_Warnings_Off (E)
4658 Has_Warnings_Off (Spec_Entity (E));
4661 return Has_Warnings_Off (E);
4663 end Warnings_Off_Check_Spec;