1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2015, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Debug; use Debug;
28 with Einfo; use Einfo;
29 with Errout; use Errout;
30 with Exp_Code; use Exp_Code;
31 with Fname; use Fname;
33 with Lib.Xref; use Lib.Xref;
34 with Namet; use Namet;
35 with Nlists; use Nlists;
37 with Par_SCO; use Par_SCO;
38 with Rtsfind; use Rtsfind;
40 with Sem_Ch8; use Sem_Ch8;
41 with Sem_Aux; use Sem_Aux;
42 with Sem_Eval; use Sem_Eval;
43 with Sem_Prag; use Sem_Prag;
44 with Sem_Util; use Sem_Util;
45 with Sinfo; use Sinfo;
46 with Sinput; use Sinput;
47 with Snames; use Snames;
48 with Stand; use Stand;
49 with Stringt; use Stringt;
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 Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean;
145 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
146 -- this is simply the setting of the flag Never_Set_In_Source. If E is
147 -- a body formal, the setting of the flag in the corresponding spec is
148 -- also checked (and False returned if either flag is False).
150 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
151 -- This function traverses the expression tree represented by the node N
152 -- and determines if any sub-operand is a reference to an entity for which
153 -- the Warnings_Off flag is set. True is returned if such an entity is
154 -- encountered, and False otherwise.
156 function Referenced_Check_Spec (E : Entity_Id) return Boolean;
157 -- Tests Referenced status for entity E. If E is not a formal, this is
158 -- simply the setting of the flag Referenced. If E is a body formal, the
159 -- setting of the flag in the corresponding spec is also checked (and True
160 -- returned if either flag is True).
162 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean;
163 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
164 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
165 -- formal, the setting of the flag in the corresponding spec is also
166 -- checked (and True returned if either flag is True).
168 function Referenced_As_Out_Parameter_Check_Spec
169 (E : Entity_Id) return Boolean;
170 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
171 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
172 -- is a body formal, the setting of the flag in the corresponding spec is
173 -- also checked (and True returned if either flag is True).
175 procedure Warn_On_Unreferenced_Entity
177 Body_E : Entity_Id := Empty);
178 -- Output warnings for unreferenced entity E. For the case of an entry
179 -- formal, Body_E is the corresponding body entity for a particular
180 -- accept statement, and the message is posted on Body_E. In all other
181 -- cases, Body_E is ignored and must be Empty.
183 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean;
184 -- Returns True if Warnings_Off is set for the entity E or (in the case
185 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
187 --------------------------
188 -- Check_Code_Statement --
189 --------------------------
191 procedure Check_Code_Statement (N : Node_Id) is
193 -- If volatile, nothing to worry about
195 if Is_Asm_Volatile (N) then
199 -- Warn if no input or no output
201 Setup_Asm_Inputs (N);
203 if No (Asm_Input_Value) then
205 ("??code statement with no inputs should usually be Volatile!", N);
209 Setup_Asm_Outputs (N);
211 if No (Asm_Output_Variable) then
213 ("??code statement with no outputs should usually be Volatile!", N);
216 end Check_Code_Statement;
218 ---------------------------------
219 -- Check_Infinite_Loop_Warning --
220 ---------------------------------
222 -- The case we look for is a while loop which tests a local variable, where
223 -- there is no obvious direct or possible indirect update of the variable
224 -- within the body of the loop.
226 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
227 Expression : Node_Id := Empty;
228 -- Set to WHILE or EXIT WHEN condition to be tested
230 Ref : Node_Id := Empty;
231 -- Reference in Expression to variable that might not be modified
232 -- in loop, indicating a possible infinite loop.
234 Var : Entity_Id := Empty;
235 -- Corresponding entity (entity of Ref)
237 Function_Call_Found : Boolean := False;
238 -- True if Find_Var found a function call in the condition
240 procedure Find_Var (N : Node_Id);
241 -- Inspect condition to see if it depends on a single entity reference.
242 -- If so, Ref is set to point to the reference node, and Var is set to
243 -- the referenced Entity.
245 function Has_Indirection (T : Entity_Id) return Boolean;
246 -- If the controlling variable is an access type, or is a record type
247 -- with access components, assume that it is changed indirectly and
248 -- suppress the warning. As a concession to low-level programming, in
249 -- particular within Declib, we also suppress warnings on a record
250 -- type that contains components of type Address or Short_Address.
252 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
253 -- Given an entity name, see if the name appears to have something to
254 -- do with I/O or network stuff, and if so, return True. Used to kill
255 -- some false positives on a heuristic basis that such functions will
256 -- likely have some strange side effect dependencies. A rather strange
257 -- test, but warning messages are in the heuristics business.
259 function Test_Ref (N : Node_Id) return Traverse_Result;
260 -- Test for reference to variable in question. Returns Abandon if
261 -- matching reference found. Used in instantiation of No_Ref_Found.
263 function No_Ref_Found is new Traverse_Func (Test_Ref);
264 -- Function to traverse body of procedure. Returns Abandon if matching
271 procedure Find_Var (N : Node_Id) is
273 -- Condition is a direct variable reference
275 if Is_Entity_Name (N) then
279 -- Case of condition is a comparison with compile time known value
281 elsif Nkind (N) in N_Op_Compare then
282 if Compile_Time_Known_Value (Right_Opnd (N)) then
283 Find_Var (Left_Opnd (N));
285 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
286 Find_Var (Right_Opnd (N));
288 -- Ignore any other comparison
294 -- If condition is a negation, check its operand
296 elsif Nkind (N) = N_Op_Not then
297 Find_Var (Right_Opnd (N));
299 -- Case of condition is function call
301 elsif Nkind (N) = N_Function_Call then
303 Function_Call_Found := True;
305 -- Forget it if function name is not entity, who knows what
306 -- we might be calling?
308 if not Is_Entity_Name (Name (N)) then
311 -- Forget it if function name is suspicious. A strange test
312 -- but warning generation is in the heuristics business.
314 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
317 -- Forget it if warnings are suppressed on function entity
319 elsif Has_Warnings_Off (Entity (Name (N))) then
323 -- OK, see if we have one argument
326 PA : constant List_Id := Parameter_Associations (N);
329 -- One argument, so check the argument
331 if Present (PA) and then List_Length (PA) = 1 then
332 if Nkind (First (PA)) = N_Parameter_Association then
333 Find_Var (Explicit_Actual_Parameter (First (PA)));
335 Find_Var (First (PA));
345 -- Any other kind of node is not something we warn for
352 ---------------------
353 -- Has_Indirection --
354 ---------------------
356 function Has_Indirection (T : Entity_Id) return Boolean is
361 if Is_Access_Type (T) then
364 elsif Is_Private_Type (T)
365 and then Present (Full_View (T))
366 and then Is_Access_Type (Full_View (T))
370 elsif Is_Record_Type (T) then
373 elsif Is_Private_Type (T)
374 and then Present (Full_View (T))
375 and then Is_Record_Type (Full_View (T))
377 Rec := Full_View (T);
382 Comp := First_Component (Rec);
383 while Present (Comp) loop
384 if Is_Access_Type (Etype (Comp))
385 or else Is_Descendent_Of_Address (Etype (Comp))
390 Next_Component (Comp);
396 ---------------------------------
397 -- Is_Suspicious_Function_Name --
398 ---------------------------------
400 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
403 function Substring_Present (S : String) return Boolean;
404 -- Returns True if name buffer has given string delimited by non-
405 -- alphabetic characters or by end of string. S is lower case.
407 -----------------------
408 -- Substring_Present --
409 -----------------------
411 function Substring_Present (S : String) return Boolean is
412 Len : constant Natural := S'Length;
415 for J in 1 .. Name_Len - (Len - 1) loop
416 if Name_Buffer (J .. J + (Len - 1)) = S
417 and then (J = 1 or else Name_Buffer (J - 1) not in 'a' .. 'z')
420 or else Name_Buffer (J + Len) not in 'a' .. 'z')
427 end Substring_Present;
429 -- Start of processing for Is_Suspicious_Function_Name
433 while Present (S) and then S /= Standard_Standard loop
434 Get_Name_String (Chars (S));
436 if Substring_Present ("io")
437 or else Substring_Present ("file")
438 or else Substring_Present ("network")
447 end Is_Suspicious_Function_Name;
453 function Test_Ref (N : Node_Id) return Traverse_Result is
455 -- Waste of time to look at the expression we are testing
457 if N = Expression then
460 -- Direct reference to variable in question
462 elsif Is_Entity_Name (N)
463 and then Present (Entity (N))
464 and then Entity (N) = Var
466 -- If this is an lvalue, then definitely abandon, since
467 -- this could be a direct modification of the variable.
469 if May_Be_Lvalue (N) then
473 -- If the condition contains a function call, we consider it may
474 -- be modified by side-effects from a procedure call. Otherwise,
475 -- we consider the condition may not be modified, although that
476 -- might happen if Variable is itself a by-reference parameter,
477 -- and the procedure called modifies the global object referred to
478 -- by Variable, but we actually prefer to issue a warning in this
479 -- odd case. Note that the case where the procedure called has
480 -- visibility over Variable is treated in another case below.
482 if Function_Call_Found then
490 exit when P = Loop_Statement;
492 -- Abandon if at procedure call, or something strange is
493 -- going on (perhaps a node with no parent that should
494 -- have one but does not?) As always, for a warning we
495 -- prefer to just abandon the warning than get into the
496 -- business of complaining about the tree structure here.
499 or else Nkind (P) = N_Procedure_Call_Statement
507 -- Reference to variable renaming variable in question
509 elsif Is_Entity_Name (N)
510 and then Present (Entity (N))
511 and then Ekind (Entity (N)) = E_Variable
512 and then Present (Renamed_Object (Entity (N)))
513 and then Is_Entity_Name (Renamed_Object (Entity (N)))
514 and then Entity (Renamed_Object (Entity (N))) = Var
515 and then May_Be_Lvalue (N)
519 -- Call to subprogram
521 elsif Nkind (N) in N_Subprogram_Call then
523 -- If subprogram is within the scope of the entity we are dealing
524 -- with as the loop variable, then it could modify this parameter,
525 -- so we abandon in this case. In the case of a subprogram that is
526 -- not an entity we also abandon. The check for no entity being
527 -- present is a defense against previous errors.
529 if not Is_Entity_Name (Name (N))
530 or else No (Entity (Name (N)))
531 or else Scope_Within (Entity (Name (N)), Scope (Var))
536 -- If any of the arguments are of type access to subprogram, then
537 -- we may have funny side effects, so no warning in this case.
542 Actual := First_Actual (N);
543 while Present (Actual) loop
544 if Is_Access_Subprogram_Type (Etype (Actual)) then
547 Next_Actual (Actual);
552 -- Declaration of the variable in question
554 elsif Nkind (N) = N_Object_Declaration
555 and then Defining_Identifier (N) = Var
560 -- All OK, continue scan
565 -- Start of processing for Check_Infinite_Loop_Warning
568 -- Skip processing if debug flag gnatd.w is set
570 if Debug_Flag_Dot_W then
574 -- Deal with Iteration scheme present
577 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
580 if Present (Iter) then
584 if Present (Condition (Iter)) then
586 -- Skip processing for while iteration with conditions actions,
587 -- since they make it too complicated to get the warning right.
589 if Present (Condition_Actions (Iter)) then
593 -- Capture WHILE condition
595 Expression := Condition (Iter);
597 -- For iteration, do not process, since loop will always terminate
599 elsif Present (Loop_Parameter_Specification (Iter)) then
605 -- Check chain of EXIT statements, we only process loops that have a
606 -- single exit condition (either a single EXIT WHEN statement, or a
607 -- WHILE loop not containing any EXIT WHEN statements).
610 Ident : constant Node_Id := Identifier (Loop_Statement);
614 -- If we don't have a proper chain set, ignore call entirely. This
615 -- happens because of previous errors.
617 if No (Entity (Ident))
618 or else Ekind (Entity (Ident)) /= E_Loop
620 Check_Error_Detected;
624 -- Otherwise prepare to scan list of EXIT statements
626 Exit_Stmt := First_Exit_Statement (Entity (Ident));
627 while Present (Exit_Stmt) loop
629 -- Check for EXIT WHEN
631 if Present (Condition (Exit_Stmt)) then
633 -- Quit processing if EXIT WHEN in WHILE loop, or more than
634 -- one EXIT WHEN statement present in the loop.
636 if Present (Expression) then
639 -- Otherwise capture condition from EXIT WHEN statement
642 Expression := Condition (Exit_Stmt);
645 -- If an unconditional exit statement is the last statement in the
646 -- loop, assume that no warning is needed, without any attempt at
647 -- checking whether the exit is reachable.
649 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then
653 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
657 -- Return if no condition to test
659 if No (Expression) then
663 -- Initial conditions met, see if condition is of right form
665 Find_Var (Expression);
667 -- Nothing to do if local variable from source not found. If it's a
668 -- renaming, it is probably renaming something too complicated to deal
672 or else Ekind (Var) /= E_Variable
673 or else Is_Library_Level_Entity (Var)
674 or else not Comes_From_Source (Var)
675 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
679 -- Nothing to do if there is some indirection involved (assume that the
680 -- designated variable might be modified in some way we don't see).
681 -- However, if no function call was found, then we don't care about
682 -- indirections, because the condition must be something like "while X
683 -- /= null loop", so we don't care if X.all is modified in the loop.
685 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
688 -- Same sort of thing for volatile variable, might be modified by
689 -- some other task or by the operating system in some way.
691 elsif Is_Volatile (Var) then
695 -- Filter out case of original statement sequence starting with delay.
696 -- We assume this is a multi-tasking program and that the condition
697 -- is affected by other threads (some kind of busy wait).
700 Fstm : constant Node_Id :=
701 Original_Node (First (Statements (Loop_Statement)));
703 if Nkind (Fstm) = N_Delay_Relative_Statement
704 or else Nkind (Fstm) = N_Delay_Until_Statement
710 -- We have a variable reference of the right form, now we scan the loop
711 -- body to see if it looks like it might not be modified
713 if No_Ref_Found (Loop_Statement) = OK then
715 ("??variable& is not modified in loop body!", Ref, Var);
717 ("\??possible infinite loop!", Ref);
719 end Check_Infinite_Loop_Warning;
721 ----------------------------
722 -- Check_Low_Bound_Tested --
723 ----------------------------
725 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
726 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id);
727 -- Determine whether operand Opnd denotes attribute 'First whose prefix
728 -- is a formal parameter. If this is the case, mark the entity of the
729 -- prefix as having its low bound tested.
731 --------------------------------
732 -- Check_Low_Bound_Tested_For --
733 --------------------------------
735 procedure Check_Low_Bound_Tested_For (Opnd : Node_Id) is
737 if Nkind (Opnd) = N_Attribute_Reference
738 and then Attribute_Name (Opnd) = Name_First
739 and then Is_Entity_Name (Prefix (Opnd))
740 and then Present (Entity (Prefix (Opnd)))
741 and then Is_Formal (Entity (Prefix (Opnd)))
743 Set_Low_Bound_Tested (Entity (Prefix (Opnd)));
745 end Check_Low_Bound_Tested_For;
747 -- Start of processing for Check_Low_Bound_Tested
750 if Comes_From_Source (Expr) then
751 Check_Low_Bound_Tested_For (Left_Opnd (Expr));
752 Check_Low_Bound_Tested_For (Right_Opnd (Expr));
754 end Check_Low_Bound_Tested;
756 ----------------------
757 -- Check_References --
758 ----------------------
760 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
767 Accept_Statement : Node_Id) return Entity_Id;
768 -- For an entry formal entity from an entry declaration, find the
769 -- corresponding body formal from the given accept statement.
771 procedure May_Need_Initialized_Actual (Ent : Entity_Id);
772 -- If an entity of a generic type has default initialization, then the
773 -- corresponding actual type should be fully initialized, or else there
774 -- will be uninitialized components in the instantiation, that might go
775 -- unreported. This routine marks the type of the uninitialized variable
776 -- appropriately to allow the compiler to emit an appropriate warning
777 -- in the instance. In a sense, the use of a type that requires full
778 -- initialization is a weak part of the generic contract.
780 function Missing_Subunits return Boolean;
781 -- We suppress warnings when there are missing subunits, because this
782 -- may generate too many false positives: entities in a parent may only
783 -- be referenced in one of the subunits. We make an exception for
784 -- subunits that contain no other stubs.
786 procedure Output_Reference_Error (M : String);
787 -- Used to output an error message. Deals with posting the error on the
788 -- body formal in the accept case.
790 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
791 -- This is true if the entity in question is potentially referenceable
792 -- from another unit. This is true for entities in packages that are at
793 -- the library level.
795 function Warnings_Off_E1 return Boolean;
796 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
797 -- or for the base type of E1T.
805 Accept_Statement : Node_Id) return Entity_Id
807 Body_Param : Node_Id;
811 -- Loop to find matching parameter in accept statement
813 Body_Param := First (Parameter_Specifications (Accept_Statement));
814 while Present (Body_Param) loop
815 Body_E := Defining_Identifier (Body_Param);
817 if Chars (Body_E) = Chars (E) then
824 -- Should never fall through, should always find a match
829 ---------------------------------
830 -- May_Need_Initialized_Actual --
831 ---------------------------------
833 procedure May_Need_Initialized_Actual (Ent : Entity_Id) is
834 T : constant Entity_Id := Etype (Ent);
835 Par : constant Node_Id := Parent (T);
838 if not Is_Generic_Type (T) then
841 elsif (Nkind (Par)) = N_Private_Extension_Declaration then
843 -- We only indicate the first such variable in the generic.
845 if No (Uninitialized_Variable (Par)) then
846 Set_Uninitialized_Variable (Par, Ent);
849 elsif (Nkind (Par)) = N_Formal_Type_Declaration
850 and then Nkind (Formal_Type_Definition (Par)) =
851 N_Formal_Private_Type_Definition
853 if No (Uninitialized_Variable (Formal_Type_Definition (Par))) then
854 Set_Uninitialized_Variable (Formal_Type_Definition (Par), Ent);
857 end May_Need_Initialized_Actual;
859 ----------------------
860 -- Missing_Subunits --
861 ----------------------
863 function Missing_Subunits return Boolean is
867 if not Unloaded_Subunits then
869 -- Normal compilation, all subunits are present
873 elsif E /= Main_Unit_Entity then
875 -- No warnings on a stub that is not the main unit
879 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
880 D := First (Declarations (Unit_Declaration_Node (E)));
881 while Present (D) loop
883 -- No warnings if the proper body contains nested stubs
885 if Nkind (D) in N_Body_Stub then
895 -- Missing stubs elsewhere
899 end Missing_Subunits;
901 ----------------------------
902 -- Output_Reference_Error --
903 ----------------------------
905 procedure Output_Reference_Error (M : String) is
907 -- Never issue messages for internal names or renamings
909 if Is_Internal_Name (Chars (E1))
910 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
915 -- Don't output message for IN OUT formal unless we have the warning
916 -- flag specifically set. It is a bit odd to distinguish IN OUT
917 -- formals from other cases. This distinction is historical in
918 -- nature. Warnings for IN OUT formals were added fairly late.
920 if Ekind (E1) = E_In_Out_Parameter
921 and then not Check_Unreferenced_Formals
926 -- Other than accept case, post error on defining identifier
931 -- Accept case, find body formal to post the message
934 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
937 end Output_Reference_Error;
939 ----------------------------
940 -- Publicly_Referenceable --
941 ----------------------------
943 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
948 -- A formal parameter is never referenceable outside the body of its
949 -- subprogram or entry.
951 if Is_Formal (Ent) then
955 -- Examine parents to look for a library level package spec. But if
956 -- we find a body or block or other similar construct along the way,
957 -- we cannot be referenced.
964 -- If we get to top of tree, then publicly referenceable
969 -- If we reach a generic package declaration, then always
970 -- consider this referenceable, since any instantiation will
971 -- have access to the entities in the generic package. Note
972 -- that the package itself may not be instantiated, but then
973 -- we will get a warning for the package entity.
975 -- Note that generic formal parameters are themselves not
976 -- publicly referenceable in an instance, and warnings on them
979 when N_Generic_Package_Declaration =>
981 not Is_List_Member (Prev)
982 or else List_Containing (Prev) /=
983 Generic_Formal_Declarations (P);
985 -- Similarly, the generic formals of a generic subprogram are
988 when N_Generic_Subprogram_Declaration =>
989 if Is_List_Member (Prev)
990 and then List_Containing (Prev) =
991 Generic_Formal_Declarations (P)
998 -- If we reach a subprogram body, entity is not referenceable
999 -- unless it is the defining entity of the body. This will
1000 -- happen, e.g. when a function is an attribute renaming that
1001 -- is rewritten as a body.
1003 when N_Subprogram_Body =>
1004 if Ent /= Defining_Entity (P) then
1010 -- If we reach any other body, definitely not referenceable
1012 when N_Package_Body |
1020 -- For all other cases, keep looking up tree
1027 end Publicly_Referenceable;
1029 ---------------------
1030 -- Warnings_Off_E1 --
1031 ---------------------
1033 function Warnings_Off_E1 return Boolean is
1035 return Has_Warnings_Off (E1T)
1036 or else Has_Warnings_Off (Base_Type (E1T))
1037 or else Warnings_Off_Check_Spec (E1);
1038 end Warnings_Off_E1;
1040 -- Start of processing for Check_References
1043 Process_Deferred_References;
1045 -- No messages if warnings are suppressed, or if we have detected any
1046 -- real errors so far (this last check avoids junk messages resulting
1047 -- from errors, e.g. a subunit that is not loaded).
1049 if Warning_Mode = Suppress or else Serious_Errors_Detected /= 0 then
1053 -- We also skip the messages if any subunits were not loaded (see
1054 -- comment in Sem_Ch10 to understand how this is set, and why it is
1055 -- necessary to suppress the warnings in this case).
1057 if Missing_Subunits then
1061 -- Otherwise loop through entities, looking for suspicious stuff
1063 E1 := First_Entity (E);
1064 while Present (E1) loop
1067 -- We are only interested in source entities. We also don't issue
1068 -- warnings within instances, since the proper place for such
1069 -- warnings is on the template when it is compiled, and we don't
1070 -- issue warnings for variables with names like Junk, Discard etc.
1072 if Comes_From_Source (E1)
1073 and then Instantiation_Location (Sloc (E1)) = No_Location
1075 -- We are interested in variables and out/in-out parameters, but
1076 -- we exclude protected types, too complicated to worry about.
1078 if Ekind (E1) = E_Variable
1080 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1081 and then not Is_Protected_Type (Current_Scope))
1083 -- If the formal has a class-wide type, retrieve its type
1084 -- because checks below depend on its private nature.
1086 if Is_Class_Wide_Type (E1T) then
1090 -- Case of an unassigned variable
1092 -- First gather any Unset_Reference indication for E1. In the
1093 -- case of a parameter, it is the Spec_Entity that is relevant.
1095 if Ekind (E1) = E_Out_Parameter
1096 and then Present (Spec_Entity (E1))
1098 UR := Unset_Reference (Spec_Entity (E1));
1100 UR := Unset_Reference (E1);
1103 -- Special processing for access types
1105 if Present (UR) and then Is_Access_Type (E1T) then
1107 -- For access types, the only time we made a UR entry was
1108 -- for a dereference, and so we post the appropriate warning
1109 -- here (note that the dereference may not be explicit in
1110 -- the source, for example in the case of a dispatching call
1111 -- with an anonymous access controlling formal, or of an
1112 -- assignment of a pointer involving discriminant check on
1113 -- the designated object).
1115 if not Warnings_Off_E1 then
1116 Error_Msg_NE ("??& may be null!", UR, E1);
1121 -- Case of variable that could be a constant. Note that we
1122 -- never signal such messages for generic package entities,
1123 -- since a given instance could have modifications outside
1126 -- Note that we used to check Address_Taken here, but we don't
1127 -- want to do that since it can be set for non-source cases,
1128 -- e.g. the Unrestricted_Access from a valid attribute, and
1129 -- the wanted effect is included in Never_Set_In_Source.
1131 elsif Warn_On_Constant
1132 and then (Ekind (E1) = E_Variable
1133 and then Has_Initial_Value (E1))
1134 and then Never_Set_In_Source_Check_Spec (E1)
1135 and then not Generic_Package_Spec_Entity (E1)
1137 -- A special case, if this variable is volatile and not
1138 -- imported, it is not helpful to tell the programmer
1139 -- to mark the variable as constant, since this would be
1140 -- illegal by virtue of RM C.6(13).
1142 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1143 and then not Is_Imported (E1)
1146 ("?k?& is not modified, volatile has no effect!", E1);
1148 -- Another special case, Exception_Occurrence, this catches
1149 -- the case of exception choice (and a bit more too, but not
1150 -- worth doing more investigation here).
1152 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1155 -- Here we give the warning if referenced and no pragma
1156 -- Unreferenced or Unmodified is present.
1161 if Ekind (E1) = E_Variable then
1162 if Referenced_Check_Spec (E1)
1163 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1164 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1166 if not Warnings_Off_E1
1167 and then not Has_Junk_Name (E1)
1169 Error_Msg_N -- CODEFIX
1170 ("?k?& is not modified, "
1171 & "could be declared constant!",
1178 -- Other cases of a variable or parameter never set in source
1180 elsif Never_Set_In_Source_Check_Spec (E1)
1182 -- No warning if warning for this case turned off
1184 and then Warn_On_No_Value_Assigned
1186 -- No warning if address taken somewhere
1188 and then not Address_Taken (E1)
1190 -- No warning if explicit initial value
1192 and then not Has_Initial_Value (E1)
1194 -- No warning for generic package spec entities, since we
1195 -- might set them in a child unit or something like that
1197 and then not Generic_Package_Spec_Entity (E1)
1199 -- No warning if fully initialized type, except that for
1200 -- this purpose we do not consider access types to qualify
1201 -- as fully initialized types (relying on an access type
1202 -- variable being null when it is never set is a bit odd).
1204 -- Also we generate warning for an out parameter that is
1205 -- never referenced, since again it seems odd to rely on
1206 -- default initialization to set an out parameter value.
1208 and then (Is_Access_Type (E1T)
1209 or else Ekind (E1) = E_Out_Parameter
1210 or else not Is_Fully_Initialized_Type (E1T))
1212 -- Do not output complaint about never being assigned a
1213 -- value if a pragma Unmodified applies to the variable
1214 -- we are examining, or if it is a parameter, if there is
1215 -- a pragma Unreferenced for the corresponding spec, or
1216 -- if the type is marked as having unreferenced objects.
1217 -- The last is a little peculiar, but better too few than
1218 -- too many warnings in this situation.
1220 if Has_Pragma_Unreferenced_Objects (E1T)
1221 or else Has_Pragma_Unmodified_Check_Spec (E1)
1225 -- IN OUT parameter case where parameter is referenced. We
1226 -- separate this out, since this is the case where we delay
1227 -- output of the warning until more information is available
1228 -- (about use in an instantiation or address being taken).
1230 elsif Ekind (E1) = E_In_Out_Parameter
1231 and then Referenced_Check_Spec (E1)
1233 -- Suppress warning if private type, and the procedure
1234 -- has a separate declaration in a different unit. This
1235 -- is the case where the client of a package sees only
1236 -- the private type, and it may be quite reasonable
1237 -- for the logical view to be IN OUT, even if the
1238 -- implementation ends up using access types or some
1239 -- other method to achieve the local effect of a
1240 -- modification. On the other hand if the spec and body
1241 -- are in the same unit, we are in the package body and
1242 -- there we have less excuse for a junk IN OUT parameter.
1244 if Has_Private_Declaration (E1T)
1245 and then Present (Spec_Entity (E1))
1246 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1250 -- Suppress warning for any parameter of a dispatching
1251 -- operation, since it is quite reasonable to have an
1252 -- operation that is overridden, and for some subclasses
1253 -- needs the formal to be IN OUT and for others happens
1254 -- not to assign it.
1256 elsif Is_Dispatching_Operation
1257 (Scope (Goto_Spec_Entity (E1)))
1261 -- Suppress warning if composite type contains any access
1262 -- component, since the logical effect of modifying a
1263 -- parameter may be achieved by modifying a referenced
1266 elsif Is_Composite_Type (E1T)
1267 and then Has_Access_Values (E1T)
1271 -- Suppress warning on formals of an entry body. All
1272 -- references are attached to the formal in the entry
1273 -- declaration, which are marked Is_Entry_Formal.
1275 elsif Ekind (Scope (E1)) = E_Entry
1276 and then not Is_Entry_Formal (E1)
1280 -- OK, looks like warning for an IN OUT parameter that
1281 -- could be IN makes sense, but we delay the output of
1282 -- the warning, pending possibly finding out later on
1283 -- that the associated subprogram is used as a generic
1284 -- actual, or its address/access is taken. In these two
1285 -- cases, we suppress the warning because the context may
1286 -- force use of IN OUT, even if in this particular case
1287 -- the formal is not modified.
1290 -- Suppress the warnings for a junk name
1292 if not Has_Junk_Name (E1) then
1293 In_Out_Warnings.Append (E1);
1297 -- Other cases of formals
1299 elsif Is_Formal (E1) then
1300 if not Is_Trivial_Subprogram (Scope (E1)) then
1301 if Referenced_Check_Spec (E1) then
1302 if not Has_Pragma_Unmodified_Check_Spec (E1)
1303 and then not Warnings_Off_E1
1304 and then not Has_Junk_Name (E1)
1306 Output_Reference_Error
1307 ("?f?formal parameter& is read but "
1308 & "never assigned!");
1311 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1312 and then not Warnings_Off_E1
1313 and then not Has_Junk_Name (E1)
1315 Output_Reference_Error
1316 ("?f?formal parameter& is not referenced!");
1323 if Referenced (E1) then
1324 if not Has_Unmodified (E1)
1325 and then not Warnings_Off_E1
1326 and then not Has_Junk_Name (E1)
1328 Output_Reference_Error
1329 ("?v?variable& is read but never assigned!");
1330 May_Need_Initialized_Actual (E1);
1333 elsif not Has_Unreferenced (E1)
1334 and then not Warnings_Off_E1
1335 and then not Has_Junk_Name (E1)
1337 Output_Reference_Error -- CODEFIX
1338 ("?v?variable& is never read and never assigned!");
1341 -- Deal with special case where this variable is hidden
1342 -- by a loop variable.
1344 if Ekind (E1) = E_Variable
1345 and then Present (Hiding_Loop_Variable (E1))
1346 and then not Warnings_Off_E1
1349 ("?v?for loop implicitly declares loop variable!",
1350 Hiding_Loop_Variable (E1));
1352 Error_Msg_Sloc := Sloc (E1);
1354 ("\?v?declaration hides & declared#!",
1355 Hiding_Loop_Variable (E1));
1362 -- Check for unset reference
1364 if Warn_On_No_Value_Assigned and then Present (UR) then
1366 -- For other than access type, go back to original node to
1367 -- deal with case where original unset reference has been
1368 -- rewritten during expansion.
1370 -- In some cases, the original node may be a type conversion
1371 -- or qualification, and in this case we want the object
1374 UR := Original_Node (UR);
1375 while Nkind (UR) = N_Type_Conversion
1376 or else Nkind (UR) = N_Qualified_Expression
1377 or else Nkind (UR) = N_Expression_With_Actions
1379 UR := Expression (UR);
1382 -- Don't issue warning if appearing inside Initial_Condition
1383 -- pragma or aspect, since that expression is not evaluated
1384 -- at the point where it occurs in the source.
1386 if In_Pragma_Expression (UR, Name_Initial_Condition) then
1390 -- Here we issue the warning, all checks completed
1392 -- If we have a return statement, this was a case of an OUT
1393 -- parameter not being set at the time of the return. (Note:
1394 -- it can't be N_Extended_Return_Statement, because those
1395 -- are only for functions, and functions do not allow OUT
1398 if not Is_Trivial_Subprogram (Scope (E1)) then
1399 if Nkind (UR) = N_Simple_Return_Statement
1400 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1402 if not Warnings_Off_E1
1403 and then not Has_Junk_Name (E1)
1406 ("?v?OUT parameter& not set before return",
1410 -- If the unset reference is a selected component
1411 -- prefix from source, mention the component as well.
1412 -- If the selected component comes from expansion, all
1413 -- we know is that the entity is not fully initialized
1414 -- at the point of the reference. Locate a random
1415 -- uninitialized component to get a better message.
1417 elsif Nkind (Parent (UR)) = N_Selected_Component then
1418 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1420 if not Comes_From_Source (Parent (UR)) then
1425 Comp := First_Entity (E1T);
1426 while Present (Comp) loop
1427 if Ekind (Comp) = E_Component
1428 and then Nkind (Parent (Comp)) =
1429 N_Component_Declaration
1430 and then No (Expression (Parent (Comp)))
1432 Error_Msg_Node_2 := Comp;
1441 -- Issue proper warning. This is a case of referencing
1442 -- a variable before it has been explicitly assigned.
1443 -- For access types, UR was only set for dereferences,
1444 -- so the issue is that the value may be null.
1446 if not Is_Trivial_Subprogram (Scope (E1)) then
1447 if not Warnings_Off_E1 then
1448 if Is_Access_Type (Etype (Parent (UR))) then
1449 Error_Msg_N ("??`&.&` may be null!", UR);
1452 ("??`&.&` may be referenced before "
1453 & "it has a value!", UR);
1458 -- All other cases of unset reference active
1460 elsif not Warnings_Off_E1 then
1462 ("??& may be referenced before it has a value!", UR);
1471 -- Then check for unreferenced entities. Note that we are only
1472 -- interested in entities whose Referenced flag is not set.
1474 if not Referenced_Check_Spec (E1)
1476 -- If Referenced_As_LHS is set, then that's still interesting
1477 -- (potential "assigned but never read" case), but not if we
1478 -- have pragma Unreferenced, which cancels this warning.
1480 and then (not Referenced_As_LHS_Check_Spec (E1)
1481 or else not Has_Unreferenced (E1))
1483 -- Check that warnings on unreferenced entities are enabled
1486 ((Check_Unreferenced and then not Is_Formal (E1))
1488 -- Case of warning on unreferenced formal
1490 or else (Check_Unreferenced_Formals and then Is_Formal (E1))
1492 -- Case of warning on unread variables modified by an
1493 -- assignment, or an OUT parameter if it is the only one.
1495 or else (Warn_On_Modified_Unread
1496 and then Referenced_As_LHS_Check_Spec (E1))
1498 -- Case of warning on any unread OUT parameter (note such
1499 -- indications are only set if the appropriate warning
1500 -- options were set, so no need to recheck here.)
1502 or else Referenced_As_Out_Parameter_Check_Spec (E1))
1504 -- All other entities, including local packages that cannot be
1505 -- referenced from elsewhere, including those declared within a
1508 and then (Is_Object (E1)
1509 or else Is_Type (E1)
1510 or else Ekind (E1) = E_Label
1511 or else Ekind_In (E1, E_Exception,
1514 or else Is_Overloadable (E1)
1516 -- Package case, if the main unit is a package spec
1517 -- or generic package spec, then there may be a
1518 -- corresponding body that references this package
1519 -- in some other file. Otherwise we can be sure
1520 -- that there is no other reference.
1523 (Ekind (E1) = E_Package
1525 not Is_Package_Or_Generic_Package
1526 (Cunit_Entity (Current_Sem_Unit))))
1528 -- Exclude instantiations, since there is no reason why every
1529 -- entity in an instantiation should be referenced.
1531 and then Instantiation_Location (Sloc (E1)) = No_Location
1533 -- Exclude formal parameters from bodies if the corresponding
1534 -- spec entity has been referenced in the case where there is
1537 and then not (Is_Formal (E1)
1538 and then Ekind (Scope (E1)) = E_Subprogram_Body
1539 and then Present (Spec_Entity (E1))
1540 and then Referenced (Spec_Entity (E1)))
1542 -- Consider private type referenced if full view is referenced.
1543 -- If there is not full view, this is a generic type on which
1544 -- warnings are also useful.
1547 not (Is_Private_Type (E1)
1548 and then Present (Full_View (E1))
1549 and then Referenced (Full_View (E1)))
1551 -- Don't worry about full view, only about private type
1553 and then not Has_Private_Declaration (E1)
1555 -- Eliminate dispatching operations from consideration, we
1556 -- cannot tell if these are referenced or not in any easy
1557 -- manner (note this also catches Adjust/Finalize/Initialize).
1559 and then not Is_Dispatching_Operation (E1)
1561 -- Check entity that can be publicly referenced (we do not give
1562 -- messages for such entities, since there could be other
1563 -- units, not involved in this compilation, that contain
1564 -- relevant references.
1566 and then not Publicly_Referenceable (E1)
1568 -- Class wide types are marked as source entities, but they are
1569 -- not really source entities, and are always created, so we do
1570 -- not care if they are not referenced.
1572 and then Ekind (E1) /= E_Class_Wide_Type
1574 -- Objects other than parameters of task types are allowed to
1575 -- be non-referenced, since they start up tasks.
1577 and then ((Ekind (E1) /= E_Variable
1578 and then Ekind (E1) /= E_Constant
1579 and then Ekind (E1) /= E_Component)
1580 or else not Is_Task_Type (E1T))
1582 -- For subunits, only place warnings on the main unit itself,
1583 -- since parent units are not completely compiled.
1585 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1586 or else Get_Source_Unit (E1) = Main_Unit)
1588 -- No warning on a return object, because these are often
1589 -- created with a single expression and an implicit return.
1590 -- If the object is a variable there will be a warning
1591 -- indicating that it could be declared constant.
1594 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1596 -- Suppress warnings in internal units if not in -gnatg mode
1597 -- (these would be junk warnings for an applications program,
1598 -- since they refer to problems in internal units).
1601 or else not Is_Internal_File_Name
1602 (Unit_File_Name (Get_Source_Unit (E1)))
1604 -- We do not immediately flag the error. This is because we
1605 -- have not expanded generic bodies yet, and they may have
1606 -- the missing reference. So instead we park the entity on a
1607 -- list, for later processing. However for the case of an
1608 -- accept statement we want to output messages now, since
1609 -- we know we already have all information at hand, and we
1610 -- also want to have separate warnings for each accept
1611 -- statement for the same entry.
1613 if Present (Anod) then
1614 pragma Assert (Is_Formal (E1));
1616 -- The unreferenced entity is E1, but post the warning
1617 -- on the body entity for this accept statement.
1619 if not Warnings_Off_E1 then
1620 Warn_On_Unreferenced_Entity
1621 (E1, Body_Formal (E1, Accept_Statement => Anod));
1624 elsif not Warnings_Off_E1
1625 and then not Has_Junk_Name (E1)
1627 Unreferenced_Entities.Append (E1);
1631 -- Generic units are referenced in the generic body, but if they
1632 -- are not public and never instantiated we want to force a
1633 -- warning on them. We treat them as redundant constructs to
1636 elsif Is_Generic_Subprogram (E1)
1637 and then not Is_Instantiated (E1)
1638 and then not Publicly_Referenceable (E1)
1639 and then Instantiation_Depth (Sloc (E1)) = 0
1640 and then Warn_On_Redundant_Constructs
1642 if not Warnings_Off_E1 and then not Has_Junk_Name (E1) then
1643 Unreferenced_Entities.Append (E1);
1645 -- Force warning on entity
1647 Set_Referenced (E1, False);
1652 -- Recurse into nested package or block. Do not recurse into a formal
1653 -- package, because the corresponding body is not analyzed.
1656 if (Is_Package_Or_Generic_Package (E1)
1657 and then Nkind (Parent (E1)) = N_Package_Specification
1659 Nkind (Original_Node (Unit_Declaration_Node (E1))) /=
1660 N_Formal_Package_Declaration)
1662 or else Ekind (E1) = E_Block
1664 Check_References (E1);
1669 end Check_References;
1671 ---------------------------
1672 -- Check_Unset_Reference --
1673 ---------------------------
1675 procedure Check_Unset_Reference (N : Node_Id) is
1676 Typ : constant Entity_Id := Etype (N);
1678 function Is_OK_Fully_Initialized return Boolean;
1679 -- This function returns true if the given node N is fully initialized
1680 -- so that the reference is safe as far as this routine is concerned.
1681 -- Safe generally means that the type of N is a fully initialized type.
1682 -- The one special case is that for access types, which are always fully
1683 -- initialized, we don't consider a dereference OK since it will surely
1684 -- be dereferencing a null value, which won't do.
1686 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1687 -- Used to test indexed or selected component or slice to see if the
1688 -- evaluation of the prefix depends on a dereference, and if so, returns
1689 -- True, in which case we always check the prefix, even if we know that
1690 -- the referenced component is initialized. Pref is the prefix to test.
1692 -----------------------------
1693 -- Is_OK_Fully_Initialized --
1694 -----------------------------
1696 function Is_OK_Fully_Initialized return Boolean is
1698 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1701 return Is_Fully_Initialized_Type (Typ);
1703 end Is_OK_Fully_Initialized;
1705 ----------------------------
1706 -- Prefix_Has_Dereference --
1707 ----------------------------
1709 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1711 -- If prefix is of an access type, it certainly needs a dereference
1713 if Is_Access_Type (Etype (Pref)) then
1716 -- If prefix is explicit dereference, that's a dereference for sure
1718 elsif Nkind (Pref) = N_Explicit_Dereference then
1721 -- If prefix is itself a component reference or slice check prefix
1723 elsif Nkind (Pref) = N_Slice
1724 or else Nkind (Pref) = N_Indexed_Component
1725 or else Nkind (Pref) = N_Selected_Component
1727 return Prefix_Has_Dereference (Prefix (Pref));
1729 -- All other cases do not involve a dereference
1734 end Prefix_Has_Dereference;
1736 -- Start of processing for Check_Unset_Reference
1739 -- Nothing to do if warnings suppressed
1741 if Warning_Mode = Suppress then
1745 -- Nothing to do for numeric or string literal. Do this test early to
1746 -- save time in a common case (it does not matter that we do not include
1747 -- character literal here, since that will be caught later on in the
1748 -- when others branch of the case statement).
1750 if Nkind (N) in N_Numeric_Or_String_Literal then
1754 -- Ignore reference unless it comes from source. Almost always if we
1755 -- have a reference from generated code, it is bogus (e.g. calls to init
1756 -- procs to set default discriminant values).
1758 if not Comes_From_Source (N) then
1762 -- Otherwise see what kind of node we have. If the entity already has an
1763 -- unset reference, it is not necessarily the earliest in the text,
1764 -- because resolution of the prefix of selected components is completed
1765 -- before the resolution of the selected component itself. As a result,
1766 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1767 -- in right-to-left order. If there is already an unset reference, we
1768 -- check whether N is earlier before proceeding.
1772 -- For identifier or expanded name, examine the entity involved
1774 when N_Identifier | N_Expanded_Name =>
1776 E : constant Entity_Id := Entity (N);
1779 if Ekind_In (E, E_Variable, E_Out_Parameter)
1780 and then Never_Set_In_Source_Check_Spec (E)
1781 and then not Has_Initial_Value (E)
1782 and then (No (Unset_Reference (E))
1784 Earlier_In_Extended_Unit
1785 (Sloc (N), Sloc (Unset_Reference (E))))
1786 and then not Has_Pragma_Unmodified_Check_Spec (E)
1787 and then not Warnings_Off_Check_Spec (E)
1788 and then not Has_Junk_Name (E)
1790 -- We may have an unset reference. The first test is whether
1791 -- this is an access to a discriminant of a record or a
1792 -- component with default initialization. Both of these
1793 -- cases can be ignored, since the actual object that is
1794 -- referenced is definitely initialized. Note that this
1795 -- covers the case of reading discriminants of an OUT
1796 -- parameter, which is OK even in Ada 83.
1798 -- Note that we are only interested in a direct reference to
1799 -- a record component here. If the reference is through an
1800 -- access type, then the access object is being referenced,
1801 -- not the record, and still deserves an unset reference.
1803 if Nkind (Parent (N)) = N_Selected_Component
1804 and not Is_Access_Type (Typ)
1807 ES : constant Entity_Id :=
1808 Entity (Selector_Name (Parent (N)));
1810 if Ekind (ES) = E_Discriminant
1812 (Present (Declaration_Node (ES))
1814 Present (Expression (Declaration_Node (ES))))
1821 -- Exclude fully initialized types
1823 if Is_OK_Fully_Initialized then
1827 -- Here we have a potential unset reference. But before we
1828 -- get worried about it, we have to make sure that the
1829 -- entity declaration is in the same procedure as the
1830 -- reference, since if they are in separate procedures, then
1831 -- we have no idea about sequential execution.
1833 -- The tests in the loop below catch all such cases, but do
1834 -- allow the reference to appear in a loop, block, or
1835 -- package spec that is nested within the declaring scope.
1836 -- As always, it is possible to construct cases where the
1837 -- warning is wrong, that is why it is a warning.
1839 Potential_Unset_Reference : declare
1841 SE : constant Entity_Id := Scope (E);
1843 function Within_Postcondition return Boolean;
1844 -- Returns True if N is within a Postcondition, a
1845 -- Refined_Post, an Ensures component in a Test_Case,
1846 -- or a Contract_Cases.
1848 --------------------------
1849 -- Within_Postcondition --
1850 --------------------------
1852 function Within_Postcondition return Boolean is
1857 while Present (Nod) loop
1858 if Nkind (Nod) = N_Pragma
1859 and then Nam_In (Pragma_Name (Nod),
1862 Name_Contract_Cases)
1866 elsif Present (Parent (Nod)) then
1869 if Nkind (P) = N_Pragma
1870 and then Pragma_Name (P) = Name_Test_Case
1871 and then Nod = Test_Case_Arg (P, Name_Ensures)
1877 Nod := Parent (Nod);
1881 end Within_Postcondition;
1883 -- Start of processing for Potential_Unset_Reference
1886 SR := Current_Scope;
1888 if SR = Standard_Standard
1889 or else Is_Subprogram (SR)
1890 or else Is_Concurrent_Body (SR)
1891 or else Is_Concurrent_Type (SR)
1899 -- Case of reference has an access type. This is a
1900 -- special case since access types are always set to null
1901 -- so cannot be truly uninitialized, but we still want to
1902 -- warn about cases of obvious null dereference.
1904 if Is_Access_Type (Typ) then
1905 Access_Type_Case : declare
1909 (N : Node_Id) return Traverse_Result;
1910 -- Process function for instantiation of Traverse
1911 -- below. Checks if N contains reference to E other
1912 -- than a dereference.
1914 function Ref_In (Nod : Node_Id) return Boolean;
1915 -- Determines whether Nod contains a reference to
1916 -- the entity E that is not a dereference.
1923 (N : Node_Id) return Traverse_Result
1926 if Is_Entity_Name (N)
1927 and then Entity (N) = E
1928 and then not Is_Dereferenced (N)
1940 function Ref_In (Nod : Node_Id) return Boolean is
1941 function Traverse is new Traverse_Func (Process);
1943 return Traverse (Nod) = Abandon;
1946 -- Start of processing for Access_Type_Case
1949 -- Don't bother if we are inside an instance, since
1950 -- the compilation of the generic template is where
1951 -- the warning should be issued.
1957 -- Don't bother if this is not the main unit. If we
1958 -- try to give this warning for with'ed units, we
1959 -- get some false positives, since we do not record
1960 -- references in other units.
1962 if not In_Extended_Main_Source_Unit (E)
1964 not In_Extended_Main_Source_Unit (N)
1969 -- We are only interested in dereferences
1971 if not Is_Dereferenced (N) then
1975 -- One more check, don't bother with references
1976 -- that are inside conditional statements or WHILE
1977 -- loops if the condition references the entity in
1978 -- question. This avoids most false positives.
1985 if Nkind_In (P, N_If_Statement, N_Elsif_Part)
1986 and then Ref_In (Condition (P))
1990 elsif Nkind (P) = N_Loop_Statement
1991 and then Present (Iteration_Scheme (P))
1993 Ref_In (Condition (Iteration_Scheme (P)))
1998 end Access_Type_Case;
2001 -- One more check, don't bother if we are within a
2002 -- postcondition, since the expression occurs in a
2003 -- place unrelated to the actual test.
2005 if not Within_Postcondition then
2007 -- Here we definitely have a case for giving a warning
2008 -- for a reference to an unset value. But we don't
2009 -- give the warning now. Instead set Unset_Reference
2010 -- in the identifier involved. The reason for this is
2011 -- that if we find the variable is never ever assigned
2012 -- a value then that warning is more important and
2013 -- there is no point in giving the reference warning.
2015 -- If this is an identifier, set the field directly
2017 if Nkind (N) = N_Identifier then
2018 Set_Unset_Reference (E, N);
2020 -- Otherwise it is an expanded name, so set the field
2021 -- of the actual identifier for the reference.
2024 Set_Unset_Reference (E, Selector_Name (N));
2027 end Potential_Unset_Reference;
2031 -- Indexed component or slice
2033 when N_Indexed_Component | N_Slice =>
2035 -- If prefix does not involve dereferencing an access type, then
2036 -- we know we are OK if the component type is fully initialized,
2037 -- since the component will have been set as part of the default
2040 if not Prefix_Has_Dereference (Prefix (N))
2041 and then Is_OK_Fully_Initialized
2045 -- Look at prefix in access type case, or if the component is not
2046 -- fully initialized.
2049 Check_Unset_Reference (Prefix (N));
2054 when N_Selected_Component =>
2056 Pref : constant Node_Id := Prefix (N);
2057 Ent : constant Entity_Id := Entity (Selector_Name (N));
2060 -- If prefix involves dereferencing an access type, always
2061 -- check the prefix, since the issue then is whether this
2062 -- access value is null.
2064 if Prefix_Has_Dereference (Pref) then
2067 -- Always go to prefix if no selector entity is set. Can this
2068 -- happen in the normal case? Not clear, but it definitely can
2069 -- happen in error cases.
2074 -- For a record component, check some cases where we have
2075 -- reasonable cause to consider that the component is known to
2076 -- be or probably is initialized. In this case, we don't care
2077 -- if the prefix itself was explicitly initialized.
2079 -- Discriminants are always considered initialized
2081 elsif Ekind (Ent) = E_Discriminant then
2084 -- An explicitly initialized component is certainly initialized
2086 elsif Nkind (Parent (Ent)) = N_Component_Declaration
2087 and then Present (Expression (Parent (Ent)))
2091 -- A fully initialized component is initialized
2093 elsif Is_OK_Fully_Initialized then
2097 -- If none of those cases apply, check the record type prefix
2099 Check_Unset_Reference (Pref);
2102 -- For type conversions, qualifications, or expressions with actions,
2103 -- examine the expression.
2105 when N_Type_Conversion |
2106 N_Qualified_Expression |
2107 N_Expression_With_Actions =>
2108 Check_Unset_Reference (Expression (N));
2110 -- For explicit dereference, always check prefix, which will generate
2111 -- an unset reference (since this is a case of dereferencing null).
2113 when N_Explicit_Dereference =>
2114 Check_Unset_Reference (Prefix (N));
2116 -- All other cases are not cases of an unset reference
2122 end Check_Unset_Reference;
2124 ------------------------
2125 -- Check_Unused_Withs --
2126 ------------------------
2128 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2134 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2135 -- This is needed for checking the special renaming case
2137 procedure Check_One_Unit (Unit : Unit_Number_Type);
2138 -- Subsidiary procedure, performs checks for specified unit
2140 --------------------
2141 -- Check_One_Unit --
2142 --------------------
2144 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2145 Is_Visible_Renaming : Boolean := False;
2148 procedure Check_Inner_Package (Pack : Entity_Id);
2149 -- Pack is a package local to a unit in a with_clause. Both the unit
2150 -- and Pack are referenced. If none of the entities in Pack are
2151 -- referenced, then the only occurrence of Pack is in a USE clause
2152 -- or a pragma, and a warning is worthwhile as well.
2154 function Check_System_Aux return Boolean;
2155 -- Before giving a warning on a with_clause for System, check whether
2156 -- a system extension is present.
2158 function Find_Package_Renaming
2160 L : Entity_Id) return Entity_Id;
2161 -- The only reference to a context unit may be in a renaming
2162 -- declaration. If this renaming declares a visible entity, do not
2163 -- warn that the context clause could be moved to the body, because
2164 -- the renaming may be intended to re-export the unit.
2166 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2167 -- This function determines if a package has any visible entities.
2168 -- True is returned if there is at least one declared visible entity,
2169 -- otherwise False is returned (e.g. case of only pragmas present).
2171 -------------------------
2172 -- Check_Inner_Package --
2173 -------------------------
2175 procedure Check_Inner_Package (Pack : Entity_Id) is
2177 Un : constant Node_Id := Sinfo.Unit (Cnode);
2179 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2180 -- If N is a use_clause for Pack, emit warning
2182 procedure Check_Use_Clauses is new
2183 Traverse_Proc (Check_Use_Clause);
2185 ----------------------
2186 -- Check_Use_Clause --
2187 ----------------------
2189 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2193 if Nkind (N) = N_Use_Package_Clause then
2194 Nam := First (Names (N));
2195 while Present (Nam) loop
2196 if Entity (Nam) = Pack then
2198 -- Suppress message if any serious errors detected
2199 -- that turn off expansion, and thus result in false
2200 -- positives for this warning.
2202 if Serious_Errors_Detected = 0 then
2203 Error_Msg_Qual_Level := 1;
2204 Error_Msg_NE -- CODEFIX
2205 ("?u?no entities of package& are referenced!",
2207 Error_Msg_Qual_Level := 0;
2216 end Check_Use_Clause;
2218 -- Start of processing for Check_Inner_Package
2221 E := First_Entity (Pack);
2222 while Present (E) loop
2223 if Referenced_Check_Spec (E) then
2230 -- No entities of the package are referenced. Check whether the
2231 -- reference to the package itself is a use clause, and if so
2232 -- place a warning on it.
2234 Check_Use_Clauses (Un);
2235 end Check_Inner_Package;
2237 ----------------------
2238 -- Check_System_Aux --
2239 ----------------------
2241 function Check_System_Aux return Boolean is
2245 if Chars (Lunit) = Name_System
2246 and then Scope (Lunit) = Standard_Standard
2247 and then Present_System_Aux
2249 Ent := First_Entity (System_Aux_Id);
2250 while Present (Ent) loop
2251 if Referenced_Check_Spec (Ent) then
2260 end Check_System_Aux;
2262 ---------------------------
2263 -- Find_Package_Renaming --
2264 ---------------------------
2266 function Find_Package_Renaming
2268 L : Entity_Id) return Entity_Id
2274 Is_Visible_Renaming := False;
2276 E1 := First_Entity (P);
2277 while Present (E1) loop
2278 if Ekind (E1) = E_Package and then Renamed_Object (E1) = L then
2279 Is_Visible_Renaming := not Is_Hidden (E1);
2282 elsif Ekind (E1) = E_Package
2283 and then No (Renamed_Object (E1))
2284 and then not Is_Generic_Instance (E1)
2286 R := Find_Package_Renaming (E1, L);
2289 Is_Visible_Renaming := not Is_Hidden (R);
2298 end Find_Package_Renaming;
2300 --------------------------
2301 -- Has_Visible_Entities --
2302 --------------------------
2304 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2308 -- If unit in context is not a package, it is a subprogram that
2309 -- is not called or a generic unit that is not instantiated
2310 -- in the current unit, and warning is appropriate.
2312 if Ekind (P) /= E_Package then
2316 -- If unit comes from a limited_with clause, look for declaration
2317 -- of shadow entities.
2319 if Present (Limited_View (P)) then
2320 E := First_Entity (Limited_View (P));
2322 E := First_Entity (P);
2325 while Present (E) and then E /= First_Private_Entity (P) loop
2326 if Comes_From_Source (E) or else Present (Limited_View (P)) then
2334 end Has_Visible_Entities;
2336 -- Start of processing for Check_One_Unit
2339 Cnode := Cunit (Unit);
2341 -- Only do check in units that are part of the extended main unit.
2342 -- This is actually a necessary restriction, because in the case of
2343 -- subprogram acting as its own specification, there can be with's in
2344 -- subunits that we will not see.
2346 if not In_Extended_Main_Source_Unit (Cnode) then
2349 -- In configurable run time mode, we remove the bodies of non-inlined
2350 -- subprograms, which may lead to spurious warnings, which are
2351 -- clearly undesirable.
2353 elsif Configurable_Run_Time_Mode
2354 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2359 -- Loop through context items in this unit
2361 Item := First (Context_Items (Cnode));
2362 while Present (Item) loop
2363 if Nkind (Item) = N_With_Clause
2364 and then not Implicit_With (Item)
2365 and then In_Extended_Main_Source_Unit (Item)
2367 -- Guard for no entity present. Not clear under what conditions
2368 -- this happens, but it does occur, and since this is only a
2369 -- warning, we just suppress the warning in this case.
2371 and then Nkind (Name (Item)) in N_Has_Entity
2372 and then Present (Entity (Name (Item)))
2374 Lunit := Entity (Name (Item));
2376 -- Check if this unit is referenced (skip the check if this
2377 -- is explicitly marked by a pragma Unreferenced).
2379 if not Referenced (Lunit) and then not Has_Unreferenced (Lunit)
2381 -- Suppress warnings in internal units if not in -gnatg mode
2382 -- (these would be junk warnings for an application program,
2383 -- since they refer to problems in internal units).
2386 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2388 -- Here we definitely have a non-referenced unit. If it
2389 -- is the special call for a spec unit, then just set the
2390 -- flag to be read later.
2392 if Unit = Spec_Unit then
2393 Set_Unreferenced_In_Spec (Item);
2395 -- Otherwise simple unreferenced message, but skip this
2396 -- if no visible entities, because that is most likely a
2397 -- case where warning would be false positive (e.g. a
2398 -- package with only a linker options pragma and nothing
2399 -- else or a pragma elaborate with a body library task).
2401 elsif Has_Visible_Entities (Entity (Name (Item))) then
2402 Error_Msg_N -- CODEFIX
2403 ("?u?unit& is not referenced!", Name (Item));
2407 -- If main unit is a renaming of this unit, then we consider
2408 -- the with to be OK (obviously it is needed in this case).
2409 -- This may be transitive: the unit in the with_clause may
2410 -- itself be a renaming, in which case both it and the main
2411 -- unit rename the same ultimate package.
2413 elsif Present (Renamed_Entity (Munite))
2415 (Renamed_Entity (Munite) = Lunit
2416 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2420 -- If this unit is referenced, and it is a package, we do
2421 -- another test, to see if any of the entities in the package
2422 -- are referenced. If none of the entities are referenced, we
2423 -- still post a warning. This occurs if the only use of the
2424 -- package is in a use clause, or in a package renaming
2425 -- declaration. This check is skipped for packages that are
2426 -- renamed in a spec, since the entities in such a package are
2427 -- visible to clients via the renaming.
2429 elsif Ekind (Lunit) = E_Package
2430 and then not Renamed_In_Spec (Lunit)
2432 -- If Is_Instantiated is set, it means that the package is
2433 -- implicitly instantiated (this is the case of parent
2434 -- instance or an actual for a generic package formal), and
2435 -- this counts as a reference.
2437 if Is_Instantiated (Lunit) then
2440 -- If no entities in package, and there is a pragma
2441 -- Elaborate_Body present, then assume that this with is
2442 -- done for purposes of this elaboration.
2444 elsif No (First_Entity (Lunit))
2445 and then Has_Pragma_Elaborate_Body (Lunit)
2449 -- Otherwise see if any entities have been referenced
2452 if Limited_Present (Item) then
2453 Ent := First_Entity (Limited_View (Lunit));
2455 Ent := First_Entity (Lunit);
2459 -- No more entities, and we did not find one that was
2460 -- referenced. Means we have a definite case of a with
2461 -- none of whose entities was referenced.
2465 -- If in spec, just set the flag
2467 if Unit = Spec_Unit then
2468 Set_No_Entities_Ref_In_Spec (Item);
2470 elsif Check_System_Aux then
2473 -- Else the warning may be needed
2477 Eitem : constant Entity_Id :=
2478 Entity (Name (Item));
2481 -- Warn if we unreferenced flag set and we
2482 -- have not had serious errors. The reason we
2483 -- inhibit the message if there are errors is
2484 -- to prevent false positives from disabling
2487 if not Has_Unreferenced (Eitem)
2488 and then Serious_Errors_Detected = 0
2490 -- Get possible package renaming
2493 Find_Package_Renaming (Munite, Lunit);
2495 -- No warning if either the package or its
2496 -- renaming is used as a generic actual.
2498 if Used_As_Generic_Actual (Eitem)
2502 Used_As_Generic_Actual (Pack))
2507 -- Here we give the warning
2509 Error_Msg_N -- CODEFIX
2510 ("?u?no entities of & are referenced!",
2513 -- Flag renaming of package as well. If
2514 -- the original package has warnings off,
2515 -- we suppress the warning on the renaming
2519 and then not Has_Warnings_Off (Lunit)
2520 and then not Has_Unreferenced (Pack)
2522 Error_Msg_NE -- CODEFIX
2523 ("?u?no entities of& are referenced!",
2524 Unit_Declaration_Node (Pack), Pack);
2532 -- Case of entity being referenced. The reference may
2533 -- come from a limited_with_clause, in which case the
2534 -- limited view of the entity carries the flag.
2536 elsif Referenced_Check_Spec (Ent)
2537 or else Referenced_As_LHS_Check_Spec (Ent)
2538 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2540 (From_Limited_With (Ent)
2541 and then Is_Incomplete_Type (Ent)
2542 and then Present (Non_Limited_View (Ent))
2543 and then Referenced (Non_Limited_View (Ent)))
2545 -- This means that the with is indeed fine, in that
2546 -- it is definitely needed somewhere, and we can
2547 -- quit worrying about this one...
2549 -- Except for one little detail: if either of the
2550 -- flags was set during spec processing, this is
2551 -- where we complain that the with could be moved
2552 -- from the spec. If the spec contains a visible
2553 -- renaming of the package, inhibit warning to move
2554 -- with_clause to body.
2556 if Ekind (Munite) = E_Package_Body then
2558 Find_Package_Renaming
2559 (Spec_Entity (Munite), Lunit);
2564 -- If a renaming is present in the spec do not warn
2565 -- because the body or child unit may depend on it.
2568 and then Renamed_Entity (Pack) = Lunit
2572 elsif Unreferenced_In_Spec (Item) then
2573 Error_Msg_N -- CODEFIX
2574 ("?u?unit& is not referenced in spec!",
2577 elsif No_Entities_Ref_In_Spec (Item) then
2578 Error_Msg_N -- CODEFIX
2579 ("?u?no entities of & are referenced in spec!",
2583 if Ekind (Ent) = E_Package then
2584 Check_Inner_Package (Ent);
2590 if not Is_Visible_Renaming then
2591 Error_Msg_N -- CODEFIX
2592 ("\?u?with clause might be moved to body!",
2598 -- Move to next entity to continue search
2606 -- For a generic package, the only interesting kind of
2607 -- reference is an instantiation, since entities cannot be
2608 -- referenced directly.
2610 elsif Is_Generic_Unit (Lunit) then
2612 -- Unit was never instantiated, set flag for case of spec
2613 -- call, or give warning for normal call.
2615 if not Is_Instantiated (Lunit) then
2616 if Unit = Spec_Unit then
2617 Set_Unreferenced_In_Spec (Item);
2619 Error_Msg_N -- CODEFIX
2620 ("?u?unit& is never instantiated!", Name (Item));
2623 -- If unit was indeed instantiated, make sure that flag is
2624 -- not set showing it was uninstantiated in the spec, and if
2625 -- so, give warning.
2627 elsif Unreferenced_In_Spec (Item) then
2629 ("?u?unit& is not instantiated in spec!", Name (Item));
2630 Error_Msg_N -- CODEFIX
2631 ("\?u?with clause can be moved to body!", Name (Item));
2640 -- Start of processing for Check_Unused_Withs
2643 -- Immediate return if no semantics or warning flag not set
2645 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then
2649 Process_Deferred_References;
2651 -- Flag any unused with clauses. For a subunit, check only the units
2652 -- in its context, not those of the parent, which may be needed by other
2653 -- subunits. We will get the full warnings when we compile the parent,
2654 -- but the following is helpful when compiling a subunit by itself.
2656 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2657 if Current_Sem_Unit = Main_Unit then
2658 Check_One_Unit (Main_Unit);
2664 -- Process specified units
2666 if Spec_Unit = No_Unit then
2668 -- For main call, check all units
2670 for Unit in Main_Unit .. Last_Unit loop
2671 Check_One_Unit (Unit);
2675 -- For call for spec, check only the spec
2677 Check_One_Unit (Spec_Unit);
2679 end Check_Unused_Withs;
2681 ---------------------------------
2682 -- Generic_Package_Spec_Entity --
2683 ---------------------------------
2685 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2689 if Is_Package_Body_Entity (E) then
2695 if S = Standard_Standard then
2698 elsif Ekind (S) = E_Generic_Package then
2701 elsif Ekind (S) = E_Package then
2709 end Generic_Package_Spec_Entity;
2711 ----------------------
2712 -- Goto_Spec_Entity --
2713 ----------------------
2715 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2717 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2718 return Spec_Entity (E);
2722 end Goto_Spec_Entity;
2728 function Has_Junk_Name (E : Entity_Id) return Boolean is
2729 function Match (S : String) return Boolean;
2730 -- Return true if substring S is found in Name_Buffer (1 .. Name_Len)
2736 function Match (S : String) return Boolean is
2737 Slen1 : constant Integer := S'Length - 1;
2740 for J in 1 .. Name_Len - S'Length + 1 loop
2741 if Name_Buffer (J .. J + Slen1) = S then
2749 -- Start of processing for Has_Junk_Name
2752 Get_Unqualified_Decoded_Name_String (Chars (E));
2755 Match ("discard") or else
2756 Match ("dummy") or else
2757 Match ("ignore") or else
2758 Match ("junk") or else
2762 --------------------------------------
2763 -- Has_Pragma_Unmodified_Check_Spec --
2764 --------------------------------------
2766 function Has_Pragma_Unmodified_Check_Spec
2767 (E : Entity_Id) return Boolean
2770 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2772 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2773 -- to mess with Unmodified flags on both body and spec entities.
2775 return Has_Unmodified (E)
2777 Has_Unmodified (Spec_Entity (E));
2780 return Has_Unmodified (E);
2782 end Has_Pragma_Unmodified_Check_Spec;
2784 ----------------------------------------
2785 -- Has_Pragma_Unreferenced_Check_Spec --
2786 ----------------------------------------
2788 function Has_Pragma_Unreferenced_Check_Spec
2789 (E : Entity_Id) return Boolean
2792 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2794 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2795 -- to mess with flags on both entities.
2797 return Has_Unreferenced (E)
2799 Has_Unreferenced (Spec_Entity (E));
2802 return Has_Unreferenced (E);
2804 end Has_Pragma_Unreferenced_Check_Spec;
2810 procedure Initialize is
2812 Warnings_Off_Pragmas.Init;
2813 Unreferenced_Entities.Init;
2814 In_Out_Warnings.Init;
2817 ------------------------------------
2818 -- Never_Set_In_Source_Check_Spec --
2819 ------------------------------------
2821 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2823 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2824 return Never_Set_In_Source (E)
2826 Never_Set_In_Source (Spec_Entity (E));
2828 return Never_Set_In_Source (E);
2830 end Never_Set_In_Source_Check_Spec;
2832 -------------------------------------
2833 -- Operand_Has_Warnings_Suppressed --
2834 -------------------------------------
2836 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2838 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2839 -- Function used to check one node to see if it is or was originally
2840 -- a reference to an entity for which Warnings are off. If so, Abandon
2841 -- is returned, otherwise OK_Orig is returned to continue the traversal
2842 -- of the original expression.
2844 function Traverse is new Traverse_Func (Check_For_Warnings);
2845 -- Function used to traverse tree looking for warnings
2847 ------------------------
2848 -- Check_For_Warnings --
2849 ------------------------
2851 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2852 R : constant Node_Id := Original_Node (N);
2855 if Nkind (R) in N_Has_Entity
2856 and then Present (Entity (R))
2857 and then Has_Warnings_Off (Entity (R))
2863 end Check_For_Warnings;
2865 -- Start of processing for Operand_Has_Warnings_Suppressed
2868 return Traverse (N) = Abandon;
2870 -- If any exception occurs, then something has gone wrong, and this is
2871 -- only a minor aesthetic issue anyway, so just say we did not find what
2872 -- we are looking for, rather than blow up.
2877 end Operand_Has_Warnings_Suppressed;
2879 -----------------------------------------
2880 -- Output_Non_Modified_In_Out_Warnings --
2881 -----------------------------------------
2883 procedure Output_Non_Modified_In_Out_Warnings is
2885 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2886 -- Given a formal parameter entity E, determines if there is a reason to
2887 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2888 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2889 -- if we have seen the address of the subprogram being taken, or if the
2890 -- subprogram is used as a generic actual (in the latter cases the
2891 -- context may force use of IN OUT, even if the parameter is not
2892 -- modifies for this particular case.
2894 -----------------------
2895 -- No_Warn_On_In_Out --
2896 -----------------------
2898 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2899 S : constant Entity_Id := Scope (E);
2900 SE : constant Entity_Id := Spec_Entity (E);
2903 -- Do not warn if address is taken, since funny business may be going
2904 -- on in treating the parameter indirectly as IN OUT.
2906 if Address_Taken (S)
2907 or else (Present (SE) and then Address_Taken (Scope (SE)))
2911 -- Do not warn if used as a generic actual, since the generic may be
2912 -- what is forcing the use of an "unnecessary" IN OUT.
2914 elsif Used_As_Generic_Actual (S)
2915 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2919 -- Else test warnings off
2921 elsif Warnings_Off_Check_Spec (S) then
2924 -- All tests for suppressing warning failed
2929 end No_Warn_On_In_Out;
2931 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2934 -- Loop through entities for which a warning may be needed
2936 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2938 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2941 -- Suppress warning in specific cases (see details in comments for
2942 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2944 if Has_Pragma_Unmodified_Check_Spec (E1)
2945 or else No_Warn_On_In_Out (E1)
2949 -- Here we generate the warning
2952 -- If -gnatwc is set then output message that we could be IN
2954 if not Is_Trivial_Subprogram (Scope (E1)) then
2955 if Warn_On_Constant then
2957 ("?u?formal parameter & is not modified!", E1);
2959 ("\?u?mode could be IN instead of `IN OUT`!", E1);
2961 -- We do not generate warnings for IN OUT parameters
2962 -- unless we have at least -gnatwu. This is deliberately
2963 -- inconsistent with the treatment of variables, but
2964 -- otherwise we get too many unexpected warnings in
2967 elsif Check_Unreferenced then
2969 ("?u?formal parameter& is read but "
2970 & "never assigned!", E1);
2974 -- Kill any other warnings on this entity, since this is the
2975 -- one that should dominate any other unreferenced warning.
2977 Set_Warnings_Off (E1);
2981 end Output_Non_Modified_In_Out_Warnings;
2983 ----------------------------------------
2984 -- Output_Obsolescent_Entity_Warnings --
2985 ----------------------------------------
2987 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2988 P : constant Node_Id := Parent (N);
2994 -- Do not output message if we are the scope of standard. This means
2995 -- we have a reference from a context clause from when it is originally
2996 -- processed, and that's too early to tell whether it is an obsolescent
2997 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2998 -- sure that we have a later call when the scope is available. This test
2999 -- also eliminates all messages for use clauses, which is fine (we do
3000 -- not want messages for use clauses, since they are always redundant
3001 -- with respect to the associated with clause).
3003 if S = Standard_Standard then
3007 -- Do not output message if we are in scope of an obsolescent package
3011 if Is_Obsolescent (S) then
3016 exit when S = Standard_Standard;
3019 -- Here we will output the message
3021 Error_Msg_Sloc := Sloc (E);
3023 -- Case of with clause
3025 if Nkind (P) = N_With_Clause then
3026 if Ekind (E) = E_Package then
3028 ("?j?with of obsolescent package& declared#", N, E);
3029 elsif Ekind (E) = E_Procedure then
3031 ("?j?with of obsolescent procedure& declared#", N, E);
3034 ("??with of obsolescent function& declared#", N, E);
3037 -- If we do not have a with clause, then ignore any reference to an
3038 -- obsolescent package name. We only want to give the one warning of
3039 -- withing the package, not one each time it is used to qualify.
3041 elsif Ekind (E) = E_Package then
3044 -- Procedure call statement
3046 elsif Nkind (P) = N_Procedure_Call_Statement then
3048 ("??call to obsolescent procedure& declared#", N, E);
3052 elsif Nkind (P) = N_Function_Call then
3054 ("??call to obsolescent function& declared#", N, E);
3056 -- Reference to obsolescent type
3058 elsif Is_Type (E) then
3060 ("??reference to obsolescent type& declared#", N, E);
3062 -- Reference to obsolescent component
3064 elsif Ekind_In (E, E_Component, E_Discriminant) then
3066 ("??reference to obsolescent component& declared#", N, E);
3068 -- Reference to obsolescent variable
3070 elsif Ekind (E) = E_Variable then
3072 ("??reference to obsolescent variable& declared#", N, E);
3074 -- Reference to obsolescent constant
3076 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then
3078 ("??reference to obsolescent constant& declared#", N, E);
3080 -- Reference to obsolescent enumeration literal
3082 elsif Ekind (E) = E_Enumeration_Literal then
3084 ("??reference to obsolescent enumeration literal& declared#", N, E);
3086 -- Generic message for any other case we missed
3090 ("??reference to obsolescent entity& declared#", N, E);
3093 -- Output additional warning if present
3095 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
3096 if Obsolescent_Warnings.Table (J).Ent = E then
3097 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
3098 Error_Msg_Strlen := Name_Len;
3099 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
3100 Error_Msg_N ("\\??~", N);
3104 end Output_Obsolescent_Entity_Warnings;
3106 ----------------------------------
3107 -- Output_Unreferenced_Messages --
3108 ----------------------------------
3110 procedure Output_Unreferenced_Messages is
3112 for J in Unreferenced_Entities.First .. Unreferenced_Entities.Last loop
3113 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
3115 end Output_Unreferenced_Messages;
3117 -----------------------------------------
3118 -- Output_Unused_Warnings_Off_Warnings --
3119 -----------------------------------------
3121 procedure Output_Unused_Warnings_Off_Warnings is
3123 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
3125 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
3126 N : Node_Id renames Wentry.N;
3127 E : Node_Id renames Wentry.E;
3130 -- Turn off Warnings_Off, or we won't get the warning
3132 Set_Warnings_Off (E, False);
3134 -- Nothing to do if pragma was used to suppress a general warning
3136 if Warnings_Off_Used (E) then
3139 -- If pragma was used both in unmodified and unreferenced contexts
3140 -- then that's as good as the general case, no warning.
3142 elsif Warnings_Off_Used_Unmodified (E)
3144 Warnings_Off_Used_Unreferenced (E)
3148 -- Used only in context where Unmodified would have worked
3150 elsif Warnings_Off_Used_Unmodified (E) then
3152 ("?W?could use Unmodified instead of "
3153 & "Warnings Off for &", Pragma_Identifier (N), E);
3155 -- Used only in context where Unreferenced would have worked
3157 elsif Warnings_Off_Used_Unreferenced (E) then
3159 ("?W?could use Unreferenced instead of "
3160 & "Warnings Off for &", Pragma_Identifier (N), E);
3166 ("?W?pragma Warnings Off for & unused, "
3167 & "could be omitted", N, E);
3171 end Output_Unused_Warnings_Off_Warnings;
3173 ---------------------------
3174 -- Referenced_Check_Spec --
3175 ---------------------------
3177 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3179 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3180 return Referenced (E) or else Referenced (Spec_Entity (E));
3182 return Referenced (E);
3184 end Referenced_Check_Spec;
3186 ----------------------------------
3187 -- Referenced_As_LHS_Check_Spec --
3188 ----------------------------------
3190 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3192 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3193 return Referenced_As_LHS (E)
3194 or else Referenced_As_LHS (Spec_Entity (E));
3196 return Referenced_As_LHS (E);
3198 end Referenced_As_LHS_Check_Spec;
3200 --------------------------------------------
3201 -- Referenced_As_Out_Parameter_Check_Spec --
3202 --------------------------------------------
3204 function Referenced_As_Out_Parameter_Check_Spec
3205 (E : Entity_Id) return Boolean
3208 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3209 return Referenced_As_Out_Parameter (E)
3210 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3212 return Referenced_As_Out_Parameter (E);
3214 end Referenced_As_Out_Parameter_Check_Spec;
3216 -----------------------------
3217 -- Warn_On_Known_Condition --
3218 -----------------------------
3220 procedure Warn_On_Known_Condition (C : Node_Id) is
3222 Orig : constant Node_Id := Original_Node (C);
3223 Test_Result : Boolean;
3225 function Is_Known_Branch return Boolean;
3226 -- If the type of the condition is Boolean, the constant value of the
3227 -- condition is a boolean literal. If the type is a derived boolean
3228 -- type, the constant is wrapped in a type conversion of the derived
3229 -- literal. If the value of the condition is not a literal, no warnings
3230 -- can be produced. This function returns True if the result can be
3231 -- determined, and Test_Result is set True/False accordingly. Otherwise
3232 -- False is returned, and Test_Result is unchanged.
3234 procedure Track (N : Node_Id; Loc : Node_Id);
3235 -- Adds continuation warning(s) pointing to reason (assignment or test)
3236 -- for the operand of the conditional having a known value (or at least
3237 -- enough is known about the value to issue the warning). N is the node
3238 -- which is judged to have a known value. Loc is the warning location.
3240 ---------------------
3241 -- Is_Known_Branch --
3242 ---------------------
3244 function Is_Known_Branch return Boolean is
3246 if Etype (C) = Standard_Boolean
3247 and then Is_Entity_Name (C)
3249 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3251 Test_Result := Entity (C) = Standard_True;
3254 elsif Is_Boolean_Type (Etype (C))
3255 and then Nkind (C) = N_Unchecked_Type_Conversion
3256 and then Is_Entity_Name (Expression (C))
3257 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3260 Chars (Entity (Expression (C))) = Chars (Standard_True);
3266 end Is_Known_Branch;
3272 procedure Track (N : Node_Id; Loc : Node_Id) is
3273 Nod : constant Node_Id := Original_Node (N);
3276 if Nkind (Nod) in N_Op_Compare then
3277 Track (Left_Opnd (Nod), Loc);
3278 Track (Right_Opnd (Nod), Loc);
3280 elsif Is_Entity_Name (Nod) and then Is_Object (Entity (Nod)) then
3282 CV : constant Node_Id := Current_Value (Entity (Nod));
3285 if Present (CV) then
3286 Error_Msg_Sloc := Sloc (CV);
3288 if Nkind (CV) not in N_Subexpr then
3289 Error_Msg_N ("\\??(see test #)", Loc);
3291 elsif Nkind (Parent (CV)) =
3292 N_Case_Statement_Alternative
3294 Error_Msg_N ("\\??(see case alternative #)", Loc);
3297 Error_Msg_N ("\\??(see assignment #)", Loc);
3304 -- Start of processing for Warn_On_Known_Condition
3307 -- Adjust SCO condition if from source
3310 and then Comes_From_Source (Orig)
3311 and then Is_Known_Branch
3317 Atrue := Test_Result;
3319 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3323 Set_SCO_Condition (Orig, Atrue);
3327 -- Argument replacement in an inlined body can make conditions static.
3328 -- Do not emit warnings in this case.
3330 if In_Inlined_Body then
3334 if Constant_Condition_Warnings
3335 and then Is_Known_Branch
3336 and then Comes_From_Source (Orig)
3337 and then not In_Instance
3339 -- Don't warn if comparison of result of attribute against a constant
3340 -- value, since this is likely legitimate conditional compilation.
3342 if Nkind (Orig) in N_Op_Compare
3343 and then Compile_Time_Known_Value (Right_Opnd (Orig))
3344 and then Nkind (Original_Node (Left_Opnd (Orig))) =
3345 N_Attribute_Reference
3350 -- See if this is in a statement or a declaration
3354 -- If tree is not attached, do not issue warning (this is very
3355 -- peculiar, and probably arises from some other error condition)
3360 -- If we are in a declaration, then no warning, since in practice
3361 -- conditionals in declarations are used for intended tests which
3362 -- may be known at compile time, e.g. things like
3364 -- x : constant Integer := 2 + (Word'Size = 32);
3366 -- And a warning is annoying in such cases
3368 elsif Nkind (P) in N_Declaration
3370 Nkind (P) in N_Later_Decl_Item
3374 -- Don't warn in assert or check pragma, since presumably tests in
3375 -- such a context are very definitely intended, and might well be
3376 -- known at compile time. Note that we have to test the original
3377 -- node, since assert pragmas get rewritten at analysis time.
3379 elsif Nkind (Original_Node (P)) = N_Pragma
3380 and then Nam_In (Pragma_Name (Original_Node (P)), Name_Assert,
3386 exit when Is_Statement (P);
3390 -- Here we issue the warning unless some sub-operand has warnings
3391 -- set off, in which case we suppress the warning for the node. If
3392 -- the original expression is an inequality, it has been expanded
3393 -- into a negation, and the value of the original expression is the
3394 -- negation of the equality. If the expression is an entity that
3395 -- appears within a negation, it is clearer to flag the negation
3396 -- itself, and report on its constant value.
3398 if not Operand_Has_Warnings_Suppressed (C) then
3400 True_Branch : Boolean := Test_Result;
3401 Cond : Node_Id := C;
3404 if Present (Parent (C))
3405 and then Nkind (Parent (C)) = N_Op_Not
3407 True_Branch := not True_Branch;
3411 -- Condition always True
3414 if Is_Entity_Name (Original_Node (C))
3415 and then Nkind (Cond) /= N_Op_Not
3418 ("object & is always True at this point?c?",
3419 Cond, Original_Node (C));
3420 Track (Original_Node (C), Cond);
3423 Error_Msg_N ("condition is always True?c?", Cond);
3427 -- Condition always False
3430 if Is_Entity_Name (Original_Node (C))
3431 and then Nkind (Cond) /= N_Op_Not
3434 ("object & is always False at this point?c?",
3435 Cond, Original_Node (C));
3436 Track (Original_Node (C), Cond);
3439 Error_Msg_N ("condition is always False?c?", Cond);
3446 end Warn_On_Known_Condition;
3448 ---------------------------------------
3449 -- Warn_On_Modified_As_Out_Parameter --
3450 ---------------------------------------
3452 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3455 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3456 or else Warn_On_All_Unread_Out_Parameters;
3457 end Warn_On_Modified_As_Out_Parameter;
3459 ---------------------------------
3460 -- Warn_On_Overlapping_Actuals --
3461 ---------------------------------
3463 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3464 Act1, Act2 : Node_Id;
3465 Form1, Form2 : Entity_Id;
3467 function Is_Covered_Formal (Formal : Node_Id) return Boolean;
3468 -- Return True if Formal is covered by the rule
3470 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean;
3471 -- Two names are known to refer to the same object if the two names
3472 -- are known to denote the same object; or one of the names is a
3473 -- selected_component, indexed_component, or slice and its prefix is
3474 -- known to refer to the same object as the other name; or one of the
3475 -- two names statically denotes a renaming declaration whose renamed
3476 -- object_name is known to refer to the same object as the other name
3477 -- (RM 6.4.1(6.11/3))
3479 -----------------------
3480 -- Refer_Same_Object --
3481 -----------------------
3483 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is
3485 return Denotes_Same_Object (Act1, Act2)
3486 or else Denotes_Same_Prefix (Act1, Act2);
3487 end Refer_Same_Object;
3489 -----------------------
3490 -- Is_Covered_Formal --
3491 -----------------------
3493 function Is_Covered_Formal (Formal : Node_Id) return Boolean is
3496 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter)
3497 and then (Is_Elementary_Type (Etype (Formal))
3498 or else Is_Record_Type (Etype (Formal))
3499 or else Is_Array_Type (Etype (Formal)));
3500 end Is_Covered_Formal;
3503 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then
3507 -- Exclude calls rewritten as enumeration literals
3509 if Nkind (N) not in N_Subprogram_Call
3510 and then Nkind (N) /= N_Entry_Call_Statement
3515 -- If a call C has two or more parameters of mode in out or out that are
3516 -- of an elementary type, then the call is legal only if for each name
3517 -- N that is passed as a parameter of mode in out or out to the call C,
3518 -- there is no other name among the other parameters of mode in out or
3519 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3521 -- If appropriate warning switch is set, we also report warnings on
3522 -- overlapping parameters that are record types or array types.
3524 Form1 := First_Formal (Subp);
3525 Act1 := First_Actual (N);
3526 while Present (Form1) and then Present (Act1) loop
3527 if Is_Covered_Formal (Form1) then
3528 Form2 := First_Formal (Subp);
3529 Act2 := First_Actual (N);
3530 while Present (Form2) and then Present (Act2) loop
3532 and then Is_Covered_Formal (Form2)
3533 and then Refer_Same_Object (Act1, Act2)
3535 -- Guard against previous errors
3538 or else No (Etype (Act1))
3539 or else No (Etype (Act2))
3543 -- If the actual is a function call in prefix notation,
3544 -- there is no real overlap.
3546 elsif Nkind (Act2) = N_Function_Call then
3549 -- If type is not by-copy, assume that aliasing is intended
3552 Present (Underlying_Type (Etype (Form1)))
3554 (Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3556 Convention (Underlying_Type (Etype (Form1))) =
3557 Convention_Ada_Pass_By_Reference)
3561 -- Under Ada 2012 we only report warnings on overlapping
3562 -- arrays and record types if switch is set.
3564 elsif Ada_Version >= Ada_2012
3565 and then not Is_Elementary_Type (Etype (Form1))
3566 and then not Warn_On_Overlap
3570 -- Here we may need to issue overlap message
3575 -- Overlap checking is an error only in Ada 2012. For
3576 -- earlier versions of Ada, this is a warning.
3578 Ada_Version < Ada_2012
3580 -- Overlap is only illegal in Ada 2012 in the case of
3581 -- elementary types (passed by copy). For other types,
3582 -- we always have a warning in all Ada versions.
3584 or else not Is_Elementary_Type (Etype (Form1))
3586 -- Finally, debug flag -gnatd.E changes the error to a
3587 -- warning even in Ada 2012 mode.
3589 or else Error_To_Warning;
3596 -- Find matching actual
3598 Act := First_Actual (N);
3599 Form := First_Formal (Subp);
3600 while Act /= Act2 loop
3605 if Is_Elementary_Type (Etype (Act1))
3606 and then Ekind (Form2) = E_In_Parameter
3608 null; -- No real aliasing
3610 elsif Is_Elementary_Type (Etype (Act2))
3611 and then Ekind (Form2) = E_In_Parameter
3615 -- If the call was written in prefix notation, and
3616 -- thus its prefix before rewriting was a selected
3617 -- component, count only visible actuals in the call.
3619 elsif Is_Entity_Name (First_Actual (N))
3620 and then Nkind (Original_Node (N)) = Nkind (N)
3621 and then Nkind (Name (Original_Node (N))) =
3622 N_Selected_Component
3624 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3626 Entity (Prefix (Name (Original_Node (N)))) =
3627 Entity (First_Actual (N))
3629 if Act1 = First_Actual (N) then
3631 ("<<`IN OUT` prefix overlaps with "
3632 & "actual for&", Act1, Form);
3635 -- For greater clarity, give name of formal
3637 Error_Msg_Node_2 := Form;
3639 ("<<writable actual for & overlaps with "
3640 & "actual for&", Act1, Form);
3644 -- For greater clarity, give name of formal
3646 Error_Msg_Node_2 := Form;
3648 -- This is one of the messages
3651 ("<<writable actual for & overlaps with "
3652 & "actual for&", Act1, Form1);
3660 Next_Formal (Form2);
3665 Next_Formal (Form1);
3668 end Warn_On_Overlapping_Actuals;
3670 ------------------------------
3671 -- Warn_On_Suspicious_Index --
3672 ------------------------------
3674 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3677 -- Set to lower bound for a suspicious type
3680 -- Entity for array reference
3685 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3686 -- Tests to see if Typ is a type for which we may have a suspicious
3687 -- index, namely an unconstrained array type, whose lower bound is
3688 -- either zero or one. If so, True is returned, and Low_Bound is set
3689 -- to this lower bound. If not, False is returned, and Low_Bound is
3690 -- undefined on return.
3692 -- For now, we limit this to standard string types, so any other
3693 -- unconstrained types return False. We may change our minds on this
3694 -- later on, but strings seem the most important case.
3696 procedure Test_Suspicious_Index;
3697 -- Test if index is of suspicious type and if so, generate warning
3699 ------------------------
3700 -- Is_Suspicious_Type --
3701 ------------------------
3703 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3707 if Is_Array_Type (Typ)
3708 and then not Is_Constrained (Typ)
3709 and then Number_Dimensions (Typ) = 1
3710 and then Is_Standard_String_Type (Typ)
3711 and then not Has_Warnings_Off (Typ)
3713 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3715 if Compile_Time_Known_Value (LB) then
3716 Low_Bound := Expr_Value (LB);
3717 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3722 end Is_Suspicious_Type;
3724 ---------------------------
3725 -- Test_Suspicious_Index --
3726 ---------------------------
3728 procedure Test_Suspicious_Index is
3730 function Length_Reference (N : Node_Id) return Boolean;
3731 -- Check if node N is of the form Name'Length
3734 -- Generate first warning line
3736 ----------------------
3737 -- Length_Reference --
3738 ----------------------
3740 function Length_Reference (N : Node_Id) return Boolean is
3741 R : constant Node_Id := Original_Node (N);
3744 Nkind (R) = N_Attribute_Reference
3745 and then Attribute_Name (R) = Name_Length
3746 and then Is_Entity_Name (Prefix (R))
3747 and then Entity (Prefix (R)) = Ent;
3748 end Length_Reference;
3756 Error_Msg_Uint_1 := Low_Bound;
3757 Error_Msg_FE -- CODEFIX
3758 ("?w?index for& may assume lower bound of^", X, Ent);
3761 -- Start of processing for Test_Suspicious_Index
3764 -- Nothing to do if subscript does not come from source (we don't
3765 -- want to give garbage warnings on compiler expanded code, e.g. the
3766 -- loops generated for slice assignments. Such junk warnings would
3767 -- be placed on source constructs with no subscript in sight).
3769 if not Comes_From_Source (Original_Node (X)) then
3773 -- Case where subscript is a constant integer
3775 if Nkind (X) = N_Integer_Literal then
3778 -- Case where original form of subscript is an integer literal
3780 if Nkind (Original_Node (X)) = N_Integer_Literal then
3781 if Intval (X) = Low_Bound then
3782 Error_Msg_FE -- CODEFIX
3783 ("\?w?suggested replacement: `&''First`", X, Ent);
3785 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3786 Error_Msg_FE -- CODEFIX
3787 ("\?w?suggested replacement: `&''First + ^`", X, Ent);
3791 -- Case where original form of subscript is more complex
3794 -- Build string X'First - 1 + expression where the expression
3795 -- is the original subscript. If the expression starts with "1
3796 -- + ", then the "- 1 + 1" is elided.
3798 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3799 Error_Msg_Strlen := 13;
3802 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3803 Tref : constant Source_Buffer_Ptr :=
3804 Source_Text (Get_Source_File_Index (Sref));
3805 -- Tref (Sref) is used to scan the subscript
3808 -- Parentheses counter when scanning subscript
3811 -- Tref (Sref) points to start of subscript
3813 -- Elide - 1 if subscript starts with 1 +
3815 if Tref (Sref .. Sref + 2) = "1 +" then
3816 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3819 elsif Tref (Sref .. Sref + 1) = "1+" then
3820 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3824 -- Now we will copy the subscript to the string buffer
3828 -- Count parens, exit if terminating right paren. Note
3829 -- check to ignore paren appearing as character literal.
3831 if Tref (Sref + 1) = '''
3833 Tref (Sref - 1) = '''
3837 if Tref (Sref) = '(' then
3839 elsif Tref (Sref) = ')' then
3845 -- Done if terminating double dot (slice case)
3848 and then (Tref (Sref .. Sref + 1) = ".."
3850 Tref (Sref .. Sref + 2) = " ..");
3852 -- Quit if we have hit EOF character, something wrong
3854 if Tref (Sref) = EOF then
3858 -- String literals are too much of a pain to handle
3860 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3864 -- If we have a 'Range reference, then this is a case
3865 -- where we cannot easily give a replacement. Don't try.
3867 if Tref (Sref .. Sref + 4) = "range"
3868 and then Tref (Sref - 1) < 'A'
3869 and then Tref (Sref + 5) < 'A'
3874 -- Else store next character
3876 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3877 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3880 -- If we get more than 40 characters then the expression
3881 -- is too long to copy, or something has gone wrong. In
3882 -- either case, just skip the attempt at a suggested fix.
3884 if Error_Msg_Strlen > 40 then
3890 -- Replacement subscript is now in string buffer
3892 Error_Msg_FE -- CODEFIX
3893 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent);
3896 -- Case where subscript is of the form X'Length
3898 elsif Length_Reference (X) then
3900 Error_Msg_Node_2 := Ent;
3902 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3905 -- Case where subscript is of the form X'Length - expression
3907 elsif Nkind (X) = N_Op_Subtract
3908 and then Length_Reference (Left_Opnd (X))
3911 Error_Msg_Node_2 := Ent;
3913 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3914 Left_Opnd (X), Ent);
3916 end Test_Suspicious_Index;
3918 -- Start of processing for Warn_On_Suspicious_Index
3921 -- Only process if warnings activated
3923 if Warn_On_Assumed_Low_Bound then
3925 -- Test if array is simple entity name
3927 if Is_Entity_Name (Name) then
3929 -- Test if array is parameter of unconstrained string type
3931 Ent := Entity (Name);
3935 and then Is_Suspicious_Type (Typ)
3936 and then not Low_Bound_Tested (Ent)
3938 Test_Suspicious_Index;
3942 end Warn_On_Suspicious_Index;
3944 -------------------------------
3945 -- Warn_On_Suspicious_Update --
3946 -------------------------------
3948 procedure Warn_On_Suspicious_Update (N : Node_Id) is
3949 Par : constant Node_Id := Parent (N);
3953 -- Only process if warnings activated
3955 if Warn_On_Suspicious_Contract then
3956 if Nkind_In (Par, N_Op_Eq, N_Op_Ne) then
3957 if N = Left_Opnd (Par) then
3958 Arg := Right_Opnd (Par);
3960 Arg := Left_Opnd (Par);
3963 if Same_Object (Prefix (N), Arg) then
3964 if Nkind (Par) = N_Op_Eq then
3966 ("suspicious equality test with modified version of "
3967 & "same object?T?", Par);
3970 ("suspicious inequality test with modified version of "
3971 & "same object?T?", Par);
3976 end Warn_On_Suspicious_Update;
3978 --------------------------------------
3979 -- Warn_On_Unassigned_Out_Parameter --
3980 --------------------------------------
3982 procedure Warn_On_Unassigned_Out_Parameter
3983 (Return_Node : Node_Id;
3984 Scope_Id : Entity_Id)
3990 -- Ignore if procedure or return statement does not come from source
3992 if not Comes_From_Source (Scope_Id)
3993 or else not Comes_From_Source (Return_Node)
3998 -- Loop through formals
4000 Form := First_Formal (Scope_Id);
4001 while Present (Form) loop
4003 -- We are only interested in OUT parameters that come from source
4004 -- and are never set in the source, and furthermore only in scalars
4005 -- since non-scalars generate too many false positives.
4007 if Ekind (Form) = E_Out_Parameter
4008 and then Never_Set_In_Source_Check_Spec (Form)
4009 and then Is_Scalar_Type (Etype (Form))
4010 and then not Present (Unset_Reference (Form))
4012 -- Before we issue the warning, an add ad hoc defence against the
4013 -- most common case of false positives with this warning which is
4014 -- the case where there is a Boolean OUT parameter that has been
4015 -- set, and whose meaning is "ignore the values of the other
4016 -- parameters". We can't of course reliably tell this case at
4017 -- compile time, but the following test kills a lot of false
4018 -- positives, without generating a significant number of false
4019 -- negatives (missed real warnings).
4021 Form2 := First_Formal (Scope_Id);
4022 while Present (Form2) loop
4023 if Ekind (Form2) = E_Out_Parameter
4024 and then Root_Type (Etype (Form2)) = Standard_Boolean
4025 and then not Never_Set_In_Source_Check_Spec (Form2)
4030 Next_Formal (Form2);
4033 -- Here all conditions are met, record possible unset reference
4035 Set_Unset_Reference (Form, Return_Node);
4040 end Warn_On_Unassigned_Out_Parameter;
4042 ---------------------------------
4043 -- Warn_On_Unreferenced_Entity --
4044 ---------------------------------
4046 procedure Warn_On_Unreferenced_Entity
4047 (Spec_E : Entity_Id;
4048 Body_E : Entity_Id := Empty)
4050 E : Entity_Id := Spec_E;
4053 if not Referenced_Check_Spec (E)
4054 and then not Has_Pragma_Unreferenced_Check_Spec (E)
4055 and then not Warnings_Off_Check_Spec (E)
4056 and then not Has_Junk_Name (Spec_E)
4057 and then not Is_Exported (Spec_E)
4062 -- Case of variable that is assigned but not read. We suppress
4063 -- the message if the variable is volatile, has an address
4064 -- clause, is aliased, or is a renaming, or is imported.
4066 if Referenced_As_LHS_Check_Spec (E)
4067 and then No (Address_Clause (E))
4068 and then not Is_Volatile (E)
4070 if Warn_On_Modified_Unread
4071 and then not Is_Imported (E)
4072 and then not Is_Aliased (E)
4073 and then No (Renamed_Object (E))
4075 if not Has_Pragma_Unmodified_Check_Spec (E) then
4076 Error_Msg_N -- CODEFIX
4077 ("?u?variable & is assigned but never read!", E);
4080 Set_Last_Assignment (E, Empty);
4083 -- Normal case of neither assigned nor read (exclude variables
4084 -- referenced as out parameters, since we already generated
4085 -- appropriate warnings at the call point in this case).
4087 elsif not Referenced_As_Out_Parameter (E) then
4089 -- We suppress the message for types for which a valid
4090 -- pragma Unreferenced_Objects has been given, otherwise
4091 -- we go ahead and give the message.
4093 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
4095 -- Distinguish renamed case in message
4097 if Present (Renamed_Object (E))
4098 and then Comes_From_Source (Renamed_Object (E))
4100 Error_Msg_N -- CODEFIX
4101 ("?u?renamed variable & is not referenced!", E);
4103 Error_Msg_N -- CODEFIX
4104 ("?u?variable & is not referenced!", E);
4110 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
4111 if Present (Renamed_Object (E))
4112 and then Comes_From_Source (Renamed_Object (E))
4114 Error_Msg_N -- CODEFIX
4115 ("?u?renamed constant & is not referenced!", E);
4117 Error_Msg_N -- CODEFIX
4118 ("?u?constant & is not referenced!", E);
4122 when E_In_Parameter |
4123 E_In_Out_Parameter =>
4125 -- Do not emit message for formals of a renaming, because
4126 -- they are never referenced explicitly.
4128 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /=
4129 N_Subprogram_Renaming_Declaration
4131 -- Suppress this message for an IN OUT parameter of a
4132 -- non-scalar type, since it is normal to have only an
4133 -- assignment in such a case.
4135 if Ekind (E) = E_In_Parameter
4136 or else not Referenced_As_LHS_Check_Spec (E)
4137 or else Is_Scalar_Type (Etype (E))
4139 if Present (Body_E) then
4143 if not Is_Trivial_Subprogram (Scope (E)) then
4144 Error_Msg_NE -- CODEFIX
4145 ("?u?formal parameter & is not referenced!",
4151 when E_Out_Parameter =>
4154 when E_Discriminant =>
4155 Error_Msg_N ("?u?discriminant & is not referenced!", E);
4157 when E_Named_Integer |
4159 Error_Msg_N -- CODEFIX
4160 ("?u?named number & is not referenced!", E);
4162 when Formal_Object_Kind =>
4163 Error_Msg_N -- CODEFIX
4164 ("?u?formal object & is not referenced!", E);
4166 when E_Enumeration_Literal =>
4167 Error_Msg_N -- CODEFIX
4168 ("?u?literal & is not referenced!", E);
4171 Error_Msg_N -- CODEFIX
4172 ("?u?function & is not referenced!", E);
4175 Error_Msg_N -- CODEFIX
4176 ("?u?procedure & is not referenced!", E);
4179 Error_Msg_N -- CODEFIX
4180 ("?u?package & is not referenced!", E);
4183 Error_Msg_N -- CODEFIX
4184 ("?u?exception & is not referenced!", E);
4187 Error_Msg_N -- CODEFIX
4188 ("?u?label & is not referenced!", E);
4190 when E_Generic_Procedure =>
4191 Error_Msg_N -- CODEFIX
4192 ("?u?generic procedure & is never instantiated!", E);
4194 when E_Generic_Function =>
4195 Error_Msg_N -- CODEFIX
4196 ("?u?generic function & is never instantiated!", E);
4199 Error_Msg_N -- CODEFIX
4200 ("?u?type & is not referenced!", E);
4203 Error_Msg_N -- CODEFIX
4204 ("?u?& is not referenced!", E);
4207 -- Kill warnings on the entity on which the message has been posted
4209 Set_Warnings_Off (E);
4211 end Warn_On_Unreferenced_Entity;
4213 --------------------------------
4214 -- Warn_On_Useless_Assignment --
4215 --------------------------------
4217 procedure Warn_On_Useless_Assignment
4219 N : Node_Id := Empty)
4224 function Check_Ref (N : Node_Id) return Traverse_Result;
4225 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4226 -- the entity in question is found.
4228 function Test_No_Refs is new Traverse_Func (Check_Ref);
4234 function Check_Ref (N : Node_Id) return Traverse_Result is
4236 -- Check reference to our identifier. We use name equality here
4237 -- because the exception handlers have not yet been analyzed. This
4238 -- is not quite right, but it really does not matter that we fail
4239 -- to output the warning in some obscure cases of name clashes.
4241 if Nkind (N) = N_Identifier and then Chars (N) = Chars (Ent) then
4248 -- Start of processing for Warn_On_Useless_Assignment
4251 -- Check if this is a case we want to warn on, a scalar or access
4252 -- variable with the last assignment field set, with warnings enabled,
4253 -- and which is not imported or exported. We also check that it is OK
4254 -- to capture the value. We are not going to capture any value, but
4255 -- the warning message depends on the same kind of conditions.
4257 if Is_Assignable (Ent)
4258 and then not Is_Return_Object (Ent)
4259 and then Present (Last_Assignment (Ent))
4260 and then not Is_Imported (Ent)
4261 and then not Is_Exported (Ent)
4262 and then Safe_To_Capture_Value (N, Ent)
4263 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
4264 and then not Has_Junk_Name (Ent)
4266 -- Before we issue the message, check covering exception handlers.
4267 -- Search up tree for enclosing statement sequences and handlers.
4269 P := Parent (Last_Assignment (Ent));
4270 while Present (P) loop
4272 -- Something is really wrong if we don't find a handled statement
4273 -- sequence, so just suppress the warning.
4276 Set_Last_Assignment (Ent, Empty);
4279 -- When we hit a package/subprogram body, issue warning and exit
4281 elsif Nkind (P) = N_Subprogram_Body
4282 or else Nkind (P) = N_Package_Body
4284 -- Case of assigned value never referenced
4288 LA : constant Node_Id := Last_Assignment (Ent);
4291 -- Don't give this for OUT and IN OUT formals, since
4292 -- clearly caller may reference the assigned value. Also
4293 -- never give such warnings for internal variables.
4295 if Ekind (Ent) = E_Variable
4296 and then not Is_Internal_Name (Chars (Ent))
4298 -- Give appropriate message, distinguishing between
4299 -- assignment statements and out parameters.
4301 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4302 N_Parameter_Association)
4305 ("?m?& modified by call, but value never "
4306 & "referenced", LA, Ent);
4309 Error_Msg_NE -- CODEFIX
4310 ("?m?useless assignment to&, value never "
4311 & "referenced!", LA, Ent);
4316 -- Case of assigned value overwritten
4320 LA : constant Node_Id := Last_Assignment (Ent);
4323 Error_Msg_Sloc := Sloc (N);
4325 -- Give appropriate message, distinguishing between
4326 -- assignment statements and out parameters.
4328 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4329 N_Parameter_Association)
4332 ("?m?& modified by call, but value overwritten #!",
4335 Error_Msg_NE -- CODEFIX
4336 ("?m?useless assignment to&, value overwritten #!",
4342 -- Clear last assignment indication and we are done
4344 Set_Last_Assignment (Ent, Empty);
4347 -- Enclosing handled sequence of statements
4349 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4351 -- Check exception handlers present
4353 if Present (Exception_Handlers (P)) then
4355 -- If we are not at the top level, we regard an inner
4356 -- exception handler as a decisive indicator that we should
4357 -- not generate the warning, since the variable in question
4358 -- may be accessed after an exception in the outer block.
4360 if Nkind (Parent (P)) /= N_Subprogram_Body
4361 and then Nkind (Parent (P)) /= N_Package_Body
4363 Set_Last_Assignment (Ent, Empty);
4366 -- Otherwise we are at the outer level. An exception
4367 -- handler is significant only if it references the
4368 -- variable in question, or if the entity in question
4369 -- is an OUT or IN OUT parameter, which which case
4370 -- the caller can reference it after the exception
4371 -- handler completes.
4374 if Is_Formal (Ent) then
4375 Set_Last_Assignment (Ent, Empty);
4379 X := First (Exception_Handlers (P));
4380 while Present (X) loop
4381 if Test_No_Refs (X) = Abandon then
4382 Set_Last_Assignment (Ent, Empty);
4396 end Warn_On_Useless_Assignment;
4398 ---------------------------------
4399 -- Warn_On_Useless_Assignments --
4400 ---------------------------------
4402 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4406 Process_Deferred_References;
4408 if Warn_On_Modified_Unread
4409 and then In_Extended_Main_Source_Unit (E)
4411 Ent := First_Entity (E);
4412 while Present (Ent) loop
4413 Warn_On_Useless_Assignment (Ent);
4417 end Warn_On_Useless_Assignments;
4419 -----------------------------
4420 -- Warnings_Off_Check_Spec --
4421 -----------------------------
4423 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4425 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4427 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4428 -- to mess with flags on both entities.
4430 return Has_Warnings_Off (E)
4432 Has_Warnings_Off (Spec_Entity (E));
4435 return Has_Warnings_Off (E);
4437 end Warnings_Off_Check_Spec;