1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2014, 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_Util; use Sem_Util;
44 with Sinfo; use Sinfo;
45 with Sinput; use Sinput;
46 with Snames; use Snames;
47 with Stand; use Stand;
48 with Stringt; use Stringt;
49 with Uintp; use Uintp;
51 package body Sem_Warn is
53 -- The following table collects Id's of entities that are potentially
54 -- unreferenced. See Check_Unset_Reference for further details.
55 -- ??? Check_Unset_Reference has zero information about this table.
57 package Unreferenced_Entities is new Table.Table (
58 Table_Component_Type => Entity_Id,
59 Table_Index_Type => Nat,
61 Table_Initial => Alloc.Unreferenced_Entities_Initial,
62 Table_Increment => Alloc.Unreferenced_Entities_Increment,
63 Table_Name => "Unreferenced_Entities");
65 -- The following table collects potential warnings for IN OUT parameters
66 -- that are referenced but not modified. These warnings are processed when
67 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
68 -- The reason that we defer output of these messages is that we want to
69 -- detect the case where the relevant procedure is used as a generic actual
70 -- in an instantiation, since we suppress the warnings in this case. The
71 -- flag Used_As_Generic_Actual will be set in this case, but only at the
72 -- point of usage. Similarly, we suppress the message if the address of the
73 -- procedure is taken, where the flag Address_Taken may be set later.
75 package In_Out_Warnings is new Table.Table (
76 Table_Component_Type => Entity_Id,
77 Table_Index_Type => Nat,
79 Table_Initial => Alloc.In_Out_Warnings_Initial,
80 Table_Increment => Alloc.In_Out_Warnings_Increment,
81 Table_Name => "In_Out_Warnings");
83 --------------------------------------------------------
84 -- Handling of Warnings Off, Unmodified, Unreferenced --
85 --------------------------------------------------------
87 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
88 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
89 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
91 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
92 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
93 -- must follow some important rules.
95 -- Call these functions as late as possible, after completing all other
96 -- tests, just before the warnings is given. For example, don't write:
98 -- if not Has_Warnings_Off (E)
99 -- and then some-other-predicate-on-E then ..
101 -- Instead the following is preferred
103 -- if some-other-predicate-on-E
104 -- and then Has_Warnings_Off (E)
106 -- This way if some-other-predicate is false, we avoid a false indication
107 -- that a Warnings (Off, E) pragma was useful in preventing a warning.
109 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
110 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
111 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
112 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
113 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
114 -- and so a subsequent test is not needed anyway (though it is harmless).
116 -----------------------
117 -- Local Subprograms --
118 -----------------------
120 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean;
121 -- This returns true if the entity E is declared within a generic package.
122 -- The point of this is to detect variables which are not assigned within
123 -- the generic, but might be assigned outside the package for any given
124 -- instance. These are cases where we leave the warnings to be posted for
125 -- the instance, when we will know more.
127 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id;
128 -- If E is a parameter entity for a subprogram body, then this function
129 -- returns the corresponding spec entity, if not, E is returned unchanged.
131 function Has_Pragma_Unmodified_Check_Spec (E : Entity_Id) return Boolean;
132 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
133 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
134 -- a body formal, the setting of the flag in the corresponding spec is
135 -- also checked (and True returned if either flag is True).
137 function Has_Pragma_Unreferenced_Check_Spec (E : Entity_Id) return Boolean;
138 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
139 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
140 -- a body formal, the setting of the flag in the corresponding spec is
141 -- also checked (and True returned if either flag is True).
143 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean;
144 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
145 -- this is simply the setting of the flag Never_Set_In_Source. If E is
146 -- a body formal, the setting of the flag in the corresponding spec is
147 -- also checked (and False returned if either flag is False).
149 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean;
150 -- This function traverses the expression tree represented by the node N
151 -- and determines if any sub-operand is a reference to an entity for which
152 -- the Warnings_Off flag is set. True is returned if such an entity is
153 -- encountered, and False otherwise.
155 function Referenced_Check_Spec (E : Entity_Id) return Boolean;
156 -- Tests Referenced status for entity E. If E is not a formal, this is
157 -- simply the setting of the flag Referenced. If E is a body formal, the
158 -- setting of the flag in the corresponding spec is also checked (and True
159 -- returned if either flag is True).
161 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean;
162 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
163 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
164 -- formal, the setting of the flag in the corresponding spec is also
165 -- checked (and True returned if either flag is True).
167 function Referenced_As_Out_Parameter_Check_Spec
168 (E : Entity_Id) return Boolean;
169 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
170 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
171 -- is a body formal, the setting of the flag in the corresponding spec is
172 -- also checked (and True returned if either flag is True).
174 procedure Warn_On_Unreferenced_Entity
176 Body_E : Entity_Id := Empty);
177 -- Output warnings for unreferenced entity E. For the case of an entry
178 -- formal, Body_E is the corresponding body entity for a particular
179 -- accept statement, and the message is posted on Body_E. In all other
180 -- cases, Body_E is ignored and must be Empty.
182 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean;
183 -- Returns True if Warnings_Off is set for the entity E or (in the case
184 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
186 --------------------------
187 -- Check_Code_Statement --
188 --------------------------
190 procedure Check_Code_Statement (N : Node_Id) is
192 -- If volatile, nothing to worry about
194 if Is_Asm_Volatile (N) then
198 -- Warn if no input or no output
200 Setup_Asm_Inputs (N);
202 if No (Asm_Input_Value) then
204 ("??code statement with no inputs should usually be Volatile!", N);
208 Setup_Asm_Outputs (N);
210 if No (Asm_Output_Variable) then
212 ("??code statement with no outputs should usually be Volatile!", N);
215 end Check_Code_Statement;
217 ---------------------------------
218 -- Check_Infinite_Loop_Warning --
219 ---------------------------------
221 -- The case we look for is a while loop which tests a local variable, where
222 -- there is no obvious direct or possible indirect update of the variable
223 -- within the body of the loop.
225 procedure Check_Infinite_Loop_Warning (Loop_Statement : Node_Id) is
226 Expression : Node_Id := Empty;
227 -- Set to WHILE or EXIT WHEN condition to be tested
229 Ref : Node_Id := Empty;
230 -- Reference in Expression to variable that might not be modified
231 -- in loop, indicating a possible infinite loop.
233 Var : Entity_Id := Empty;
234 -- Corresponding entity (entity of Ref)
236 Function_Call_Found : Boolean := False;
237 -- True if Find_Var found a function call in the condition
239 procedure Find_Var (N : Node_Id);
240 -- Inspect condition to see if it depends on a single entity reference.
241 -- If so, Ref is set to point to the reference node, and Var is set to
242 -- the referenced Entity.
244 function Has_Indirection (T : Entity_Id) return Boolean;
245 -- If the controlling variable is an access type, or is a record type
246 -- with access components, assume that it is changed indirectly and
247 -- suppress the warning. As a concession to low-level programming, in
248 -- particular within Declib, we also suppress warnings on a record
249 -- type that contains components of type Address or Short_Address.
251 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean;
252 -- Given an entity name, see if the name appears to have something to
253 -- do with I/O or network stuff, and if so, return True. Used to kill
254 -- some false positives on a heuristic basis that such functions will
255 -- likely have some strange side effect dependencies. A rather strange
256 -- test, but warning messages are in the heuristics business.
258 function Test_Ref (N : Node_Id) return Traverse_Result;
259 -- Test for reference to variable in question. Returns Abandon if
260 -- matching reference found. Used in instantiation of No_Ref_Found.
262 function No_Ref_Found is new Traverse_Func (Test_Ref);
263 -- Function to traverse body of procedure. Returns Abandon if matching
270 procedure Find_Var (N : Node_Id) is
272 -- Condition is a direct variable reference
274 if Is_Entity_Name (N) then
278 -- Case of condition is a comparison with compile time known value
280 elsif Nkind (N) in N_Op_Compare then
281 if Compile_Time_Known_Value (Right_Opnd (N)) then
282 Find_Var (Left_Opnd (N));
284 elsif Compile_Time_Known_Value (Left_Opnd (N)) then
285 Find_Var (Right_Opnd (N));
287 -- Ignore any other comparison
293 -- If condition is a negation, check its operand
295 elsif Nkind (N) = N_Op_Not then
296 Find_Var (Right_Opnd (N));
298 -- Case of condition is function call
300 elsif Nkind (N) = N_Function_Call then
302 Function_Call_Found := True;
304 -- Forget it if function name is not entity, who knows what
305 -- we might be calling?
307 if not Is_Entity_Name (Name (N)) then
310 -- Forget it if function name is suspicious. A strange test
311 -- but warning generation is in the heuristics business.
313 elsif Is_Suspicious_Function_Name (Entity (Name (N))) then
316 -- Forget it if warnings are suppressed on function entity
318 elsif Has_Warnings_Off (Entity (Name (N))) then
322 -- OK, see if we have one argument
325 PA : constant List_Id := Parameter_Associations (N);
328 -- One argument, so check the argument
330 if Present (PA) and then List_Length (PA) = 1 then
331 if Nkind (First (PA)) = N_Parameter_Association then
332 Find_Var (Explicit_Actual_Parameter (First (PA)));
334 Find_Var (First (PA));
344 -- Any other kind of node is not something we warn for
351 ---------------------
352 -- Has_Indirection --
353 ---------------------
355 function Has_Indirection (T : Entity_Id) return Boolean is
360 if Is_Access_Type (T) then
363 elsif Is_Private_Type (T)
364 and then Present (Full_View (T))
365 and then Is_Access_Type (Full_View (T))
369 elsif Is_Record_Type (T) then
372 elsif Is_Private_Type (T)
373 and then Present (Full_View (T))
374 and then Is_Record_Type (Full_View (T))
376 Rec := Full_View (T);
381 Comp := First_Component (Rec);
382 while Present (Comp) loop
383 if Is_Access_Type (Etype (Comp))
384 or else Is_Descendent_Of_Address (Etype (Comp))
389 Next_Component (Comp);
395 ---------------------------------
396 -- Is_Suspicious_Function_Name --
397 ---------------------------------
399 function Is_Suspicious_Function_Name (E : Entity_Id) return Boolean is
402 function Substring_Present (S : String) return Boolean;
403 -- Returns True if name buffer has given string delimited by non-
404 -- alphabetic characters or by end of string. S is lower case.
406 -----------------------
407 -- Substring_Present --
408 -----------------------
410 function Substring_Present (S : String) return Boolean is
411 Len : constant Natural := S'Length;
414 for J in 1 .. Name_Len - (Len - 1) loop
415 if Name_Buffer (J .. J + (Len - 1)) = S
416 and then (J = 1 or else Name_Buffer (J - 1) not in 'a' .. 'z')
419 or else Name_Buffer (J + Len) not in 'a' .. 'z')
426 end Substring_Present;
428 -- Start of processing for Is_Suspicious_Function_Name
432 while Present (S) and then S /= Standard_Standard loop
433 Get_Name_String (Chars (S));
435 if Substring_Present ("io")
436 or else Substring_Present ("file")
437 or else Substring_Present ("network")
446 end Is_Suspicious_Function_Name;
452 function Test_Ref (N : Node_Id) return Traverse_Result is
454 -- Waste of time to look at the expression we are testing
456 if N = Expression then
459 -- Direct reference to variable in question
461 elsif Is_Entity_Name (N)
462 and then Present (Entity (N))
463 and then Entity (N) = Var
465 -- If this is an lvalue, then definitely abandon, since
466 -- this could be a direct modification of the variable.
468 if May_Be_Lvalue (N) then
472 -- If the condition contains a function call, we consider it may
473 -- be modified by side-effects from a procedure call. Otherwise,
474 -- we consider the condition may not be modified, although that
475 -- might happen if Variable is itself a by-reference parameter,
476 -- and the procedure called modifies the global object referred to
477 -- by Variable, but we actually prefer to issue a warning in this
478 -- odd case. Note that the case where the procedure called has
479 -- visibility over Variable is treated in another case below.
481 if Function_Call_Found then
489 exit when P = Loop_Statement;
491 -- Abandon if at procedure call, or something strange is
492 -- going on (perhaps a node with no parent that should
493 -- have one but does not?) As always, for a warning we
494 -- prefer to just abandon the warning than get into the
495 -- business of complaining about the tree structure here.
498 or else Nkind (P) = N_Procedure_Call_Statement
506 -- Reference to variable renaming variable in question
508 elsif Is_Entity_Name (N)
509 and then Present (Entity (N))
510 and then Ekind (Entity (N)) = E_Variable
511 and then Present (Renamed_Object (Entity (N)))
512 and then Is_Entity_Name (Renamed_Object (Entity (N)))
513 and then Entity (Renamed_Object (Entity (N))) = Var
514 and then May_Be_Lvalue (N)
518 -- Call to subprogram
520 elsif Nkind (N) in N_Subprogram_Call then
522 -- If subprogram is within the scope of the entity we are dealing
523 -- with as the loop variable, then it could modify this parameter,
524 -- so we abandon in this case. In the case of a subprogram that is
525 -- not an entity we also abandon. The check for no entity being
526 -- present is a defense against previous errors.
528 if not Is_Entity_Name (Name (N))
529 or else No (Entity (Name (N)))
530 or else Scope_Within (Entity (Name (N)), Scope (Var))
535 -- If any of the arguments are of type access to subprogram, then
536 -- we may have funny side effects, so no warning in this case.
541 Actual := First_Actual (N);
542 while Present (Actual) loop
543 if Is_Access_Subprogram_Type (Etype (Actual)) then
546 Next_Actual (Actual);
551 -- Declaration of the variable in question
553 elsif Nkind (N) = N_Object_Declaration
554 and then Defining_Identifier (N) = Var
559 -- All OK, continue scan
564 -- Start of processing for Check_Infinite_Loop_Warning
567 -- Skip processing if debug flag gnatd.w is set
569 if Debug_Flag_Dot_W then
573 -- Deal with Iteration scheme present
576 Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
579 if Present (Iter) then
583 if Present (Condition (Iter)) then
585 -- Skip processing for while iteration with conditions actions,
586 -- since they make it too complicated to get the warning right.
588 if Present (Condition_Actions (Iter)) then
592 -- Capture WHILE condition
594 Expression := Condition (Iter);
596 -- For iteration, do not process, since loop will always terminate
598 elsif Present (Loop_Parameter_Specification (Iter)) then
604 -- Check chain of EXIT statements, we only process loops that have a
605 -- single exit condition (either a single EXIT WHEN statement, or a
606 -- WHILE loop not containing any EXIT WHEN statements).
609 Ident : constant Node_Id := Identifier (Loop_Statement);
613 -- If we don't have a proper chain set, ignore call entirely. This
614 -- happens because of previous errors.
616 if No (Entity (Ident))
617 or else Ekind (Entity (Ident)) /= E_Loop
619 Check_Error_Detected;
623 -- Otherwise prepare to scan list of EXIT statements
625 Exit_Stmt := First_Exit_Statement (Entity (Ident));
626 while Present (Exit_Stmt) loop
628 -- Check for EXIT WHEN
630 if Present (Condition (Exit_Stmt)) then
632 -- Quit processing if EXIT WHEN in WHILE loop, or more than
633 -- one EXIT WHEN statement present in the loop.
635 if Present (Expression) then
638 -- Otherwise capture condition from EXIT WHEN statement
641 Expression := Condition (Exit_Stmt);
644 -- If an unconditional exit statement is the last statement in the
645 -- loop, assume that no warning is needed, without any attempt at
646 -- checking whether the exit is reachable.
648 elsif Exit_Stmt = Last (Statements (Loop_Statement)) then
652 Exit_Stmt := Next_Exit_Statement (Exit_Stmt);
656 -- Return if no condition to test
658 if No (Expression) then
662 -- Initial conditions met, see if condition is of right form
664 Find_Var (Expression);
666 -- Nothing to do if local variable from source not found. If it's a
667 -- renaming, it is probably renaming something too complicated to deal
671 or else Ekind (Var) /= E_Variable
672 or else Is_Library_Level_Entity (Var)
673 or else not Comes_From_Source (Var)
674 or else Nkind (Parent (Var)) = N_Object_Renaming_Declaration
678 -- Nothing to do if there is some indirection involved (assume that the
679 -- designated variable might be modified in some way we don't see).
680 -- However, if no function call was found, then we don't care about
681 -- indirections, because the condition must be something like "while X
682 -- /= null loop", so we don't care if X.all is modified in the loop.
684 elsif Function_Call_Found and then Has_Indirection (Etype (Var)) then
687 -- Same sort of thing for volatile variable, might be modified by
688 -- some other task or by the operating system in some way.
690 elsif Is_Volatile (Var) then
694 -- Filter out case of original statement sequence starting with delay.
695 -- We assume this is a multi-tasking program and that the condition
696 -- is affected by other threads (some kind of busy wait).
699 Fstm : constant Node_Id :=
700 Original_Node (First (Statements (Loop_Statement)));
702 if Nkind (Fstm) = N_Delay_Relative_Statement
703 or else Nkind (Fstm) = N_Delay_Until_Statement
709 -- We have a variable reference of the right form, now we scan the loop
710 -- body to see if it looks like it might not be modified
712 if No_Ref_Found (Loop_Statement) = OK then
714 ("??variable& is not modified in loop body!", Ref, Var);
716 ("\??possible infinite loop!", Ref);
718 end Check_Infinite_Loop_Warning;
720 ----------------------------
721 -- Check_Low_Bound_Tested --
722 ----------------------------
724 procedure Check_Low_Bound_Tested (Expr : Node_Id) is
726 if Comes_From_Source (Expr) then
728 L : constant Node_Id := Left_Opnd (Expr);
729 R : constant Node_Id := Right_Opnd (Expr);
731 if Nkind (L) = N_Attribute_Reference
732 and then Attribute_Name (L) = Name_First
733 and then Is_Entity_Name (Prefix (L))
734 and then Is_Formal (Entity (Prefix (L)))
736 Set_Low_Bound_Tested (Entity (Prefix (L)));
739 if Nkind (R) = N_Attribute_Reference
740 and then Attribute_Name (R) = Name_First
741 and then Is_Entity_Name (Prefix (R))
742 and then Is_Formal (Entity (Prefix (R)))
744 Set_Low_Bound_Tested (Entity (Prefix (R)));
748 end Check_Low_Bound_Tested;
750 ----------------------
751 -- Check_References --
752 ----------------------
754 procedure Check_References (E : Entity_Id; Anod : Node_Id := Empty) is
761 Accept_Statement : Node_Id) return Entity_Id;
762 -- For an entry formal entity from an entry declaration, find the
763 -- corresponding body formal from the given accept statement.
765 procedure May_Need_Initialized_Actual (Ent : Entity_Id);
766 -- If an entity of a generic type has default initialization, then the
767 -- corresponding actual type should be fully initialized, or else there
768 -- will be uninitialized components in the instantiation, that might go
769 -- unreported. This routine marks the type of the uninitialized variable
770 -- appropriately to allow the compiler to emit an appropriate warning
771 -- in the instance. In a sense, the use of a type that requires full
772 -- initialization is a weak part of the generic contract.
774 function Missing_Subunits return Boolean;
775 -- We suppress warnings when there are missing subunits, because this
776 -- may generate too many false positives: entities in a parent may only
777 -- be referenced in one of the subunits. We make an exception for
778 -- subunits that contain no other stubs.
780 procedure Output_Reference_Error (M : String);
781 -- Used to output an error message. Deals with posting the error on the
782 -- body formal in the accept case.
784 function Publicly_Referenceable (Ent : Entity_Id) return Boolean;
785 -- This is true if the entity in question is potentially referenceable
786 -- from another unit. This is true for entities in packages that are at
787 -- the library level.
789 function Warnings_Off_E1 return Boolean;
790 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
791 -- or for the base type of E1T.
799 Accept_Statement : Node_Id) return Entity_Id
801 Body_Param : Node_Id;
805 -- Loop to find matching parameter in accept statement
807 Body_Param := First (Parameter_Specifications (Accept_Statement));
808 while Present (Body_Param) loop
809 Body_E := Defining_Identifier (Body_Param);
811 if Chars (Body_E) = Chars (E) then
818 -- Should never fall through, should always find a match
823 -----------------------------------
824 -- May_Need_Initialized_Actual --
825 -----------------------------------
827 procedure May_Need_Initialized_Actual (Ent : Entity_Id) is
828 T : constant Entity_Id := Etype (Ent);
829 Par : constant Node_Id := Parent (T);
832 if not Is_Generic_Type (T) then
835 elsif (Nkind (Par)) = N_Private_Extension_Declaration then
837 -- We only indicate the first such variable in the generic.
839 if No (Uninitialized_Variable (Par)) then
840 Set_Uninitialized_Variable (Par, Ent);
843 elsif (Nkind (Par)) = N_Formal_Type_Declaration
844 and then Nkind (Formal_Type_Definition (Par)) =
845 N_Formal_Private_Type_Definition
847 if No (Uninitialized_Variable (Formal_Type_Definition (Par))) then
848 Set_Uninitialized_Variable (Formal_Type_Definition (Par), Ent);
851 end May_Need_Initialized_Actual;
853 ----------------------
854 -- Missing_Subunits --
855 ----------------------
857 function Missing_Subunits return Boolean is
861 if not Unloaded_Subunits then
863 -- Normal compilation, all subunits are present
867 elsif E /= Main_Unit_Entity then
869 -- No warnings on a stub that is not the main unit
873 elsif Nkind (Unit_Declaration_Node (E)) in N_Proper_Body then
874 D := First (Declarations (Unit_Declaration_Node (E)));
875 while Present (D) loop
877 -- No warnings if the proper body contains nested stubs
879 if Nkind (D) in N_Body_Stub then
889 -- Missing stubs elsewhere
893 end Missing_Subunits;
895 ----------------------------
896 -- Output_Reference_Error --
897 ----------------------------
899 procedure Output_Reference_Error (M : String) is
901 -- Never issue messages for internal names, nor for renamings
903 if Is_Internal_Name (Chars (E1))
904 or else Nkind (Parent (E1)) = N_Object_Renaming_Declaration
909 -- Don't output message for IN OUT formal unless we have the warning
910 -- flag specifically set. It is a bit odd to distinguish IN OUT
911 -- formals from other cases. This distinction is historical in
912 -- nature. Warnings for IN OUT formals were added fairly late.
914 if Ekind (E1) = E_In_Out_Parameter
915 and then not Check_Unreferenced_Formals
920 -- Other than accept case, post error on defining identifier
925 -- Accept case, find body formal to post the message
928 Error_Msg_NE (M, Body_Formal (E1, Accept_Statement => Anod), E1);
931 end Output_Reference_Error;
933 ----------------------------
934 -- Publicly_Referenceable --
935 ----------------------------
937 function Publicly_Referenceable (Ent : Entity_Id) return Boolean is
942 -- A formal parameter is never referenceable outside the body of its
943 -- subprogram or entry.
945 if Is_Formal (Ent) then
949 -- Examine parents to look for a library level package spec. But if
950 -- we find a body or block or other similar construct along the way,
951 -- we cannot be referenced.
958 -- If we get to top of tree, then publicly referenceable
963 -- If we reach a generic package declaration, then always
964 -- consider this referenceable, since any instantiation will
965 -- have access to the entities in the generic package. Note
966 -- that the package itself may not be instantiated, but then
967 -- we will get a warning for the package entity.
969 -- Note that generic formal parameters are themselves not
970 -- publicly referenceable in an instance, and warnings on them
973 when N_Generic_Package_Declaration =>
975 not Is_List_Member (Prev)
976 or else List_Containing (Prev) /=
977 Generic_Formal_Declarations (P);
979 -- Similarly, the generic formals of a generic subprogram are
982 when N_Generic_Subprogram_Declaration =>
983 if Is_List_Member (Prev)
984 and then List_Containing (Prev) =
985 Generic_Formal_Declarations (P)
992 -- If we reach a subprogram body, entity is not referenceable
993 -- unless it is the defining entity of the body. This will
994 -- happen, e.g. when a function is an attribute renaming that
995 -- is rewritten as a body.
997 when N_Subprogram_Body =>
998 if Ent /= Defining_Entity (P) then
1004 -- If we reach any other body, definitely not referenceable
1006 when N_Package_Body |
1014 -- For all other cases, keep looking up tree
1021 end Publicly_Referenceable;
1023 ---------------------
1024 -- Warnings_Off_E1 --
1025 ---------------------
1027 function Warnings_Off_E1 return Boolean is
1029 return Has_Warnings_Off (E1T)
1030 or else Has_Warnings_Off (Base_Type (E1T))
1031 or else Warnings_Off_Check_Spec (E1);
1032 end Warnings_Off_E1;
1034 -- Start of processing for Check_References
1037 Process_Deferred_References;
1039 -- No messages if warnings are suppressed, or if we have detected any
1040 -- real errors so far (this last check avoids junk messages resulting
1041 -- from errors, e.g. a subunit that is not loaded).
1043 if Warning_Mode = Suppress or else Serious_Errors_Detected /= 0 then
1047 -- We also skip the messages if any subunits were not loaded (see
1048 -- comment in Sem_Ch10 to understand how this is set, and why it is
1049 -- necessary to suppress the warnings in this case).
1051 if Missing_Subunits then
1055 -- Otherwise loop through entities, looking for suspicious stuff
1057 E1 := First_Entity (E);
1058 while Present (E1) loop
1061 -- We are only interested in source entities. We also don't issue
1062 -- warnings within instances, since the proper place for such
1063 -- warnings is on the template when it is compiled.
1065 if Comes_From_Source (E1)
1066 and then Instantiation_Location (Sloc (E1)) = No_Location
1068 -- We are interested in variables and out/in-out parameters, but
1069 -- we exclude protected types, too complicated to worry about.
1071 if Ekind (E1) = E_Variable
1073 (Ekind_In (E1, E_Out_Parameter, E_In_Out_Parameter)
1074 and then not Is_Protected_Type (Current_Scope))
1076 -- Case of an unassigned variable
1078 -- First gather any Unset_Reference indication for E1. In the
1079 -- case of a parameter, it is the Spec_Entity that is relevant.
1081 if Ekind (E1) = E_Out_Parameter
1082 and then Present (Spec_Entity (E1))
1084 UR := Unset_Reference (Spec_Entity (E1));
1086 UR := Unset_Reference (E1);
1089 -- Special processing for access types
1091 if Present (UR) and then Is_Access_Type (E1T) then
1093 -- For access types, the only time we made a UR entry was
1094 -- for a dereference, and so we post the appropriate warning
1095 -- here (note that the dereference may not be explicit in
1096 -- the source, for example in the case of a dispatching call
1097 -- with an anonymous access controlling formal, or of an
1098 -- assignment of a pointer involving discriminant check on
1099 -- the designated object).
1101 if not Warnings_Off_E1 then
1102 Error_Msg_NE ("??& may be null!", UR, E1);
1107 -- Case of variable that could be a constant. Note that we
1108 -- never signal such messages for generic package entities,
1109 -- since a given instance could have modifications outside
1112 elsif Warn_On_Constant
1113 and then (Ekind (E1) = E_Variable
1114 and then Has_Initial_Value (E1))
1115 and then Never_Set_In_Source_Check_Spec (E1)
1116 and then not Address_Taken (E1)
1117 and then not Generic_Package_Spec_Entity (E1)
1119 -- A special case, if this variable is volatile and not
1120 -- imported, it is not helpful to tell the programmer
1121 -- to mark the variable as constant, since this would be
1122 -- illegal by virtue of RM C.6(13).
1124 if (Is_Volatile (E1) or else Has_Volatile_Components (E1))
1125 and then not Is_Imported (E1)
1128 ("?k?& is not modified, volatile has no effect!", E1);
1130 -- Another special case, Exception_Occurrence, this catches
1131 -- the case of exception choice (and a bit more too, but not
1132 -- worth doing more investigation here).
1134 elsif Is_RTE (E1T, RE_Exception_Occurrence) then
1137 -- Here we give the warning if referenced and no pragma
1138 -- Unreferenced or Unmodified is present.
1143 if Ekind (E1) = E_Variable then
1144 if Referenced_Check_Spec (E1)
1145 and then not Has_Pragma_Unreferenced_Check_Spec (E1)
1146 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1148 if not Warnings_Off_E1 then
1149 Error_Msg_N -- CODEFIX
1150 ("?k?& is not modified, "
1151 & "could be declared constant!",
1158 -- Other cases of a variable or parameter never set in source
1160 elsif Never_Set_In_Source_Check_Spec (E1)
1162 -- No warning if warning for this case turned off
1164 and then Warn_On_No_Value_Assigned
1166 -- No warning if address taken somewhere
1168 and then not Address_Taken (E1)
1170 -- No warning if explicit initial value
1172 and then not Has_Initial_Value (E1)
1174 -- No warning for generic package spec entities, since we
1175 -- might set them in a child unit or something like that
1177 and then not Generic_Package_Spec_Entity (E1)
1179 -- No warning if fully initialized type, except that for
1180 -- this purpose we do not consider access types to qualify
1181 -- as fully initialized types (relying on an access type
1182 -- variable being null when it is never set is a bit odd).
1184 -- Also we generate warning for an out parameter that is
1185 -- never referenced, since again it seems odd to rely on
1186 -- default initialization to set an out parameter value.
1188 and then (Is_Access_Type (E1T)
1189 or else Ekind (E1) = E_Out_Parameter
1190 or else not Is_Fully_Initialized_Type (E1T))
1192 -- Do not output complaint about never being assigned a
1193 -- value if a pragma Unmodified applies to the variable
1194 -- we are examining, or if it is a parameter, if there is
1195 -- a pragma Unreferenced for the corresponding spec, or
1196 -- if the type is marked as having unreferenced objects.
1197 -- The last is a little peculiar, but better too few than
1198 -- too many warnings in this situation.
1200 if Has_Pragma_Unreferenced_Objects (E1T)
1201 or else Has_Pragma_Unmodified_Check_Spec (E1)
1205 -- IN OUT parameter case where parameter is referenced. We
1206 -- separate this out, since this is the case where we delay
1207 -- output of the warning until more information is available
1208 -- (about use in an instantiation or address being taken).
1210 elsif Ekind (E1) = E_In_Out_Parameter
1211 and then Referenced_Check_Spec (E1)
1213 -- Suppress warning if private type, and the procedure
1214 -- has a separate declaration in a different unit. This
1215 -- is the case where the client of a package sees only
1216 -- the private type, and it may be quite reasonable
1217 -- for the logical view to be IN OUT, even if the
1218 -- implementation ends up using access types or some
1219 -- other method to achieve the local effect of a
1220 -- modification. On the other hand if the spec and body
1221 -- are in the same unit, we are in the package body and
1222 -- there we have less excuse for a junk IN OUT parameter.
1224 if Has_Private_Declaration (E1T)
1225 and then Present (Spec_Entity (E1))
1226 and then not In_Same_Source_Unit (E1, Spec_Entity (E1))
1230 -- Suppress warning for any parameter of a dispatching
1231 -- operation, since it is quite reasonable to have an
1232 -- operation that is overridden, and for some subclasses
1233 -- needs the formal to be IN OUT and for others happens
1234 -- not to assign it.
1236 elsif Is_Dispatching_Operation
1237 (Scope (Goto_Spec_Entity (E1)))
1241 -- Suppress warning if composite type contains any access
1242 -- component, since the logical effect of modifying a
1243 -- parameter may be achieved by modifying a referenced
1246 elsif Is_Composite_Type (E1T)
1247 and then Has_Access_Values (E1T)
1251 -- Suppress warning on formals of an entry body. All
1252 -- references are attached to the formal in the entry
1253 -- declaration, which are marked Is_Entry_Formal.
1255 elsif Ekind (Scope (E1)) = E_Entry
1256 and then not Is_Entry_Formal (E1)
1260 -- OK, looks like warning for an IN OUT parameter that
1261 -- could be IN makes sense, but we delay the output of
1262 -- the warning, pending possibly finding out later on
1263 -- that the associated subprogram is used as a generic
1264 -- actual, or its address/access is taken. In these two
1265 -- cases, we suppress the warning because the context may
1266 -- force use of IN OUT, even if in this particular case
1267 -- the formal is not modified.
1270 In_Out_Warnings.Append (E1);
1273 -- Other cases of formals
1275 elsif Is_Formal (E1) then
1276 if not Is_Trivial_Subprogram (Scope (E1)) then
1277 if Referenced_Check_Spec (E1) then
1278 if not Has_Pragma_Unmodified_Check_Spec (E1)
1279 and then not Warnings_Off_E1
1281 Output_Reference_Error
1282 ("?f?formal parameter& is read but "
1283 & "never assigned!");
1286 elsif not Has_Pragma_Unreferenced_Check_Spec (E1)
1287 and then not Warnings_Off_E1
1289 Output_Reference_Error
1290 ("?f?formal parameter& is not referenced!");
1297 if Referenced (E1) then
1298 if not Has_Unmodified (E1)
1299 and then not Warnings_Off_E1
1300 and then not Is_Junk_Name (Chars (E1))
1302 Output_Reference_Error
1303 ("?v?variable& is read but never assigned!");
1304 May_Need_Initialized_Actual (E1);
1307 elsif not Has_Unreferenced (E1)
1308 and then not Warnings_Off_E1
1309 and then not Is_Junk_Name (Chars (E1))
1311 Output_Reference_Error -- CODEFIX
1312 ("?v?variable& is never read and never assigned!");
1315 -- Deal with special case where this variable is hidden
1316 -- by a loop variable.
1318 if Ekind (E1) = E_Variable
1319 and then Present (Hiding_Loop_Variable (E1))
1320 and then not Warnings_Off_E1
1323 ("?v?for loop implicitly declares loop variable!",
1324 Hiding_Loop_Variable (E1));
1326 Error_Msg_Sloc := Sloc (E1);
1328 ("\?v?declaration hides & declared#!",
1329 Hiding_Loop_Variable (E1));
1336 -- Check for unset reference
1338 if Warn_On_No_Value_Assigned and then Present (UR) then
1340 -- For other than access type, go back to original node to
1341 -- deal with case where original unset reference has been
1342 -- rewritten during expansion.
1344 -- In some cases, the original node may be a type conversion
1345 -- or qualification, and in this case we want the object
1348 UR := Original_Node (UR);
1349 while Nkind (UR) = N_Type_Conversion
1350 or else Nkind (UR) = N_Qualified_Expression
1351 or else Nkind (UR) = N_Expression_With_Actions
1353 UR := Expression (UR);
1356 -- Don't issue warning if appearing inside Initial_Condition
1357 -- pragma or aspect, since that expression is not evaluated
1358 -- at the point where it occurs in the source.
1360 if In_Pragma_Expression (UR, Name_Initial_Condition) then
1364 -- Here we issue the warning, all checks completed
1366 -- If we have a return statement, this was a case of an OUT
1367 -- parameter not being set at the time of the return. (Note:
1368 -- it can't be N_Extended_Return_Statement, because those
1369 -- are only for functions, and functions do not allow OUT
1372 if not Is_Trivial_Subprogram (Scope (E1)) then
1373 if Nkind (UR) = N_Simple_Return_Statement
1374 and then not Has_Pragma_Unmodified_Check_Spec (E1)
1376 if not Warnings_Off_E1 then
1378 ("?v?OUT parameter& not set before return",
1382 -- If the unset reference is a selected component
1383 -- prefix from source, mention the component as well.
1384 -- If the selected component comes from expansion, all
1385 -- we know is that the entity is not fully initialized
1386 -- at the point of the reference. Locate a random
1387 -- uninitialized component to get a better message.
1389 elsif Nkind (Parent (UR)) = N_Selected_Component then
1390 Error_Msg_Node_2 := Selector_Name (Parent (UR));
1392 if not Comes_From_Source (Parent (UR)) then
1397 Comp := First_Entity (E1T);
1398 while Present (Comp) loop
1399 if Ekind (Comp) = E_Component
1400 and then Nkind (Parent (Comp)) =
1401 N_Component_Declaration
1402 and then No (Expression (Parent (Comp)))
1404 Error_Msg_Node_2 := Comp;
1413 -- Issue proper warning. This is a case of referencing
1414 -- a variable before it has been explicitly assigned.
1415 -- For access types, UR was only set for dereferences,
1416 -- so the issue is that the value may be null.
1418 if not Is_Trivial_Subprogram (Scope (E1)) then
1419 if not Warnings_Off_E1 then
1420 if Is_Access_Type (Etype (Parent (UR))) then
1421 Error_Msg_N ("??`&.&` may be null!", UR);
1424 ("??`&.&` may be referenced before "
1425 & "it has a value!", UR);
1430 -- All other cases of unset reference active
1432 elsif not Warnings_Off_E1 then
1434 ("??& may be referenced before it has a value!", UR);
1443 -- Then check for unreferenced entities. Note that we are only
1444 -- interested in entities whose Referenced flag is not set.
1446 if not Referenced_Check_Spec (E1)
1448 -- If Referenced_As_LHS is set, then that's still interesting
1449 -- (potential "assigned but never read" case), but not if we
1450 -- have pragma Unreferenced, which cancels this warning.
1452 and then (not Referenced_As_LHS_Check_Spec (E1)
1453 or else not Has_Unreferenced (E1))
1455 -- Check that warnings on unreferenced entities are enabled
1458 ((Check_Unreferenced and then not Is_Formal (E1))
1460 -- Case of warning on unreferenced formal
1462 or else (Check_Unreferenced_Formals and then Is_Formal (E1))
1464 -- Case of warning on unread variables modified by an
1465 -- assignment, or an OUT parameter if it is the only one.
1467 or else (Warn_On_Modified_Unread
1468 and then Referenced_As_LHS_Check_Spec (E1))
1470 -- Case of warning on any unread OUT parameter (note such
1471 -- indications are only set if the appropriate warning
1472 -- options were set, so no need to recheck here.)
1474 or else Referenced_As_Out_Parameter_Check_Spec (E1))
1476 -- All other entities, including local packages that cannot be
1477 -- referenced from elsewhere, including those declared within a
1480 and then (Is_Object (E1)
1481 or else Is_Type (E1)
1482 or else Ekind (E1) = E_Label
1483 or else Ekind_In (E1, E_Exception,
1486 or else Is_Overloadable (E1)
1488 -- Package case, if the main unit is a package spec
1489 -- or generic package spec, then there may be a
1490 -- corresponding body that references this package
1491 -- in some other file. Otherwise we can be sure
1492 -- that there is no other reference.
1495 (Ekind (E1) = E_Package
1497 not Is_Package_Or_Generic_Package
1498 (Cunit_Entity (Current_Sem_Unit))))
1500 -- Exclude instantiations, since there is no reason why every
1501 -- entity in an instantiation should be referenced.
1503 and then Instantiation_Location (Sloc (E1)) = No_Location
1505 -- Exclude formal parameters from bodies if the corresponding
1506 -- spec entity has been referenced in the case where there is
1509 and then not (Is_Formal (E1)
1510 and then Ekind (Scope (E1)) = E_Subprogram_Body
1511 and then Present (Spec_Entity (E1))
1512 and then Referenced (Spec_Entity (E1)))
1514 -- Consider private type referenced if full view is referenced.
1515 -- If there is not full view, this is a generic type on which
1516 -- warnings are also useful.
1519 not (Is_Private_Type (E1)
1520 and then Present (Full_View (E1))
1521 and then Referenced (Full_View (E1)))
1523 -- Don't worry about full view, only about private type
1525 and then not Has_Private_Declaration (E1)
1527 -- Eliminate dispatching operations from consideration, we
1528 -- cannot tell if these are referenced or not in any easy
1529 -- manner (note this also catches Adjust/Finalize/Initialize).
1531 and then not Is_Dispatching_Operation (E1)
1533 -- Check entity that can be publicly referenced (we do not give
1534 -- messages for such entities, since there could be other
1535 -- units, not involved in this compilation, that contain
1536 -- relevant references.
1538 and then not Publicly_Referenceable (E1)
1540 -- Class wide types are marked as source entities, but they are
1541 -- not really source entities, and are always created, so we do
1542 -- not care if they are not referenced.
1544 and then Ekind (E1) /= E_Class_Wide_Type
1546 -- Objects other than parameters of task types are allowed to
1547 -- be non-referenced, since they start up tasks.
1549 and then ((Ekind (E1) /= E_Variable
1550 and then Ekind (E1) /= E_Constant
1551 and then Ekind (E1) /= E_Component)
1552 or else not Is_Task_Type (E1T))
1554 -- For subunits, only place warnings on the main unit itself,
1555 -- since parent units are not completely compiled.
1557 and then (Nkind (Unit (Cunit (Main_Unit))) /= N_Subunit
1558 or else Get_Source_Unit (E1) = Main_Unit)
1560 -- No warning on a return object, because these are often
1561 -- created with a single expression and an implicit return.
1562 -- If the object is a variable there will be a warning
1563 -- indicating that it could be declared constant.
1566 (Ekind (E1) = E_Constant and then Is_Return_Object (E1))
1568 -- Suppress warnings in internal units if not in -gnatg mode
1569 -- (these would be junk warnings for an applications program,
1570 -- since they refer to problems in internal units).
1573 or else not Is_Internal_File_Name
1574 (Unit_File_Name (Get_Source_Unit (E1)))
1576 -- We do not immediately flag the error. This is because we
1577 -- have not expanded generic bodies yet, and they may have
1578 -- the missing reference. So instead we park the entity on a
1579 -- list, for later processing. However for the case of an
1580 -- accept statement we want to output messages now, since
1581 -- we know we already have all information at hand, and we
1582 -- also want to have separate warnings for each accept
1583 -- statement for the same entry.
1585 if Present (Anod) then
1586 pragma Assert (Is_Formal (E1));
1588 -- The unreferenced entity is E1, but post the warning
1589 -- on the body entity for this accept statement.
1591 if not Warnings_Off_E1 then
1592 Warn_On_Unreferenced_Entity
1593 (E1, Body_Formal (E1, Accept_Statement => Anod));
1596 elsif not Warnings_Off_E1 then
1597 Unreferenced_Entities.Append (E1);
1601 -- Generic units are referenced in the generic body, but if they
1602 -- are not public and never instantiated we want to force a
1603 -- warning on them. We treat them as redundant constructs to
1606 elsif Is_Generic_Subprogram (E1)
1607 and then not Is_Instantiated (E1)
1608 and then not Publicly_Referenceable (E1)
1609 and then Instantiation_Depth (Sloc (E1)) = 0
1610 and then Warn_On_Redundant_Constructs
1612 if not Warnings_Off_E1 then
1613 Unreferenced_Entities.Append (E1);
1615 -- Force warning on entity
1617 Set_Referenced (E1, False);
1622 -- Recurse into nested package or block. Do not recurse into a formal
1623 -- package, because the corresponding body is not analyzed.
1626 if (Is_Package_Or_Generic_Package (E1)
1627 and then Nkind (Parent (E1)) = N_Package_Specification
1629 Nkind (Original_Node (Unit_Declaration_Node (E1))) /=
1630 N_Formal_Package_Declaration)
1632 or else Ekind (E1) = E_Block
1634 Check_References (E1);
1639 end Check_References;
1641 ---------------------------
1642 -- Check_Unset_Reference --
1643 ---------------------------
1645 procedure Check_Unset_Reference (N : Node_Id) is
1646 Typ : constant Entity_Id := Etype (N);
1648 function Is_OK_Fully_Initialized return Boolean;
1649 -- This function returns true if the given node N is fully initialized
1650 -- so that the reference is safe as far as this routine is concerned.
1651 -- Safe generally means that the type of N is a fully initialized type.
1652 -- The one special case is that for access types, which are always fully
1653 -- initialized, we don't consider a dereference OK since it will surely
1654 -- be dereferencing a null value, which won't do.
1656 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean;
1657 -- Used to test indexed or selected component or slice to see if the
1658 -- evaluation of the prefix depends on a dereference, and if so, returns
1659 -- True, in which case we always check the prefix, even if we know that
1660 -- the referenced component is initialized. Pref is the prefix to test.
1662 -----------------------------
1663 -- Is_OK_Fully_Initialized --
1664 -----------------------------
1666 function Is_OK_Fully_Initialized return Boolean is
1668 if Is_Access_Type (Typ) and then Is_Dereferenced (N) then
1671 return Is_Fully_Initialized_Type (Typ);
1673 end Is_OK_Fully_Initialized;
1675 ----------------------------
1676 -- Prefix_Has_Dereference --
1677 ----------------------------
1679 function Prefix_Has_Dereference (Pref : Node_Id) return Boolean is
1681 -- If prefix is of an access type, it certainly needs a dereference
1683 if Is_Access_Type (Etype (Pref)) then
1686 -- If prefix is explicit dereference, that's a dereference for sure
1688 elsif Nkind (Pref) = N_Explicit_Dereference then
1691 -- If prefix is itself a component reference or slice check prefix
1693 elsif Nkind (Pref) = N_Slice
1694 or else Nkind (Pref) = N_Indexed_Component
1695 or else Nkind (Pref) = N_Selected_Component
1697 return Prefix_Has_Dereference (Prefix (Pref));
1699 -- All other cases do not involve a dereference
1704 end Prefix_Has_Dereference;
1706 -- Start of processing for Check_Unset_Reference
1709 -- Nothing to do if warnings suppressed
1711 if Warning_Mode = Suppress then
1715 -- Nothing to do for numeric or string literal. Do this test early to
1716 -- save time in a common case (it does not matter that we do not include
1717 -- character literal here, since that will be caught later on in the
1718 -- when others branch of the case statement).
1720 if Nkind (N) in N_Numeric_Or_String_Literal then
1724 -- Ignore reference unless it comes from source. Almost always if we
1725 -- have a reference from generated code, it is bogus (e.g. calls to init
1726 -- procs to set default discriminant values).
1728 if not Comes_From_Source (N) then
1732 -- Otherwise see what kind of node we have. If the entity already has an
1733 -- unset reference, it is not necessarily the earliest in the text,
1734 -- because resolution of the prefix of selected components is completed
1735 -- before the resolution of the selected component itself. As a result,
1736 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1737 -- in right-to-left order. If there is already an unset reference, we
1738 -- check whether N is earlier before proceeding.
1742 -- For identifier or expanded name, examine the entity involved
1744 when N_Identifier | N_Expanded_Name =>
1746 E : constant Entity_Id := Entity (N);
1749 if Ekind_In (E, E_Variable, E_Out_Parameter)
1750 and then Never_Set_In_Source_Check_Spec (E)
1751 and then not Has_Initial_Value (E)
1752 and then (No (Unset_Reference (E))
1754 Earlier_In_Extended_Unit
1755 (Sloc (N), Sloc (Unset_Reference (E))))
1756 and then not Has_Pragma_Unmodified_Check_Spec (E)
1757 and then not Warnings_Off_Check_Spec (E)
1759 -- We may have an unset reference. The first test is whether
1760 -- this is an access to a discriminant of a record or a
1761 -- component with default initialization. Both of these
1762 -- cases can be ignored, since the actual object that is
1763 -- referenced is definitely initialized. Note that this
1764 -- covers the case of reading discriminants of an OUT
1765 -- parameter, which is OK even in Ada 83.
1767 -- Note that we are only interested in a direct reference to
1768 -- a record component here. If the reference is through an
1769 -- access type, then the access object is being referenced,
1770 -- not the record, and still deserves an unset reference.
1772 if Nkind (Parent (N)) = N_Selected_Component
1773 and not Is_Access_Type (Typ)
1776 ES : constant Entity_Id :=
1777 Entity (Selector_Name (Parent (N)));
1779 if Ekind (ES) = E_Discriminant
1781 (Present (Declaration_Node (ES))
1783 Present (Expression (Declaration_Node (ES))))
1790 -- Exclude fully initialized types
1792 if Is_OK_Fully_Initialized then
1796 -- Here we have a potential unset reference. But before we
1797 -- get worried about it, we have to make sure that the
1798 -- entity declaration is in the same procedure as the
1799 -- reference, since if they are in separate procedures, then
1800 -- we have no idea about sequential execution.
1802 -- The tests in the loop below catch all such cases, but do
1803 -- allow the reference to appear in a loop, block, or
1804 -- package spec that is nested within the declaring scope.
1805 -- As always, it is possible to construct cases where the
1806 -- warning is wrong, that is why it is a warning.
1808 Potential_Unset_Reference : declare
1810 SE : constant Entity_Id := Scope (E);
1812 function Within_Postcondition return Boolean;
1813 -- Returns True if N is within a Postcondition, a
1814 -- Refined_Post, an Ensures component in a Test_Case,
1815 -- or a Contract_Cases.
1817 --------------------------
1818 -- Within_Postcondition --
1819 --------------------------
1821 function Within_Postcondition return Boolean is
1826 while Present (Nod) loop
1827 if Nkind (Nod) = N_Pragma
1828 and then Nam_In (Pragma_Name (Nod),
1831 Name_Contract_Cases)
1835 elsif Present (Parent (Nod)) then
1838 if Nkind (P) = N_Pragma
1839 and then Pragma_Name (P) = Name_Test_Case
1840 and then Nod = Get_Ensures_From_CTC_Pragma (P)
1846 Nod := Parent (Nod);
1850 end Within_Postcondition;
1852 -- Start of processing for Potential_Unset_Reference
1855 SR := Current_Scope;
1857 if SR = Standard_Standard
1858 or else Is_Subprogram (SR)
1859 or else Is_Concurrent_Body (SR)
1860 or else Is_Concurrent_Type (SR)
1868 -- Case of reference has an access type. This is a
1869 -- special case since access types are always set to null
1870 -- so cannot be truly uninitialized, but we still want to
1871 -- warn about cases of obvious null dereference.
1873 if Is_Access_Type (Typ) then
1874 Access_Type_Case : declare
1878 (N : Node_Id) return Traverse_Result;
1879 -- Process function for instantiation of Traverse
1880 -- below. Checks if N contains reference to E other
1881 -- than a dereference.
1883 function Ref_In (Nod : Node_Id) return Boolean;
1884 -- Determines whether Nod contains a reference to
1885 -- the entity E that is not a dereference.
1892 (N : Node_Id) return Traverse_Result
1895 if Is_Entity_Name (N)
1896 and then Entity (N) = E
1897 and then not Is_Dereferenced (N)
1909 function Ref_In (Nod : Node_Id) return Boolean is
1910 function Traverse is new Traverse_Func (Process);
1912 return Traverse (Nod) = Abandon;
1915 -- Start of processing for Access_Type_Case
1918 -- Don't bother if we are inside an instance, since
1919 -- the compilation of the generic template is where
1920 -- the warning should be issued.
1926 -- Don't bother if this is not the main unit. If we
1927 -- try to give this warning for with'ed units, we
1928 -- get some false positives, since we do not record
1929 -- references in other units.
1931 if not In_Extended_Main_Source_Unit (E)
1933 not In_Extended_Main_Source_Unit (N)
1938 -- We are only interested in dereferences
1940 if not Is_Dereferenced (N) then
1944 -- One more check, don't bother with references
1945 -- that are inside conditional statements or WHILE
1946 -- loops if the condition references the entity in
1947 -- question. This avoids most false positives.
1954 if Nkind_In (P, N_If_Statement, N_Elsif_Part)
1955 and then Ref_In (Condition (P))
1959 elsif Nkind (P) = N_Loop_Statement
1960 and then Present (Iteration_Scheme (P))
1962 Ref_In (Condition (Iteration_Scheme (P)))
1967 end Access_Type_Case;
1970 -- One more check, don't bother if we are within a
1971 -- postcondition, since the expression occurs in a
1972 -- place unrelated to the actual test.
1974 if not Within_Postcondition then
1976 -- Here we definitely have a case for giving a warning
1977 -- for a reference to an unset value. But we don't
1978 -- give the warning now. Instead set Unset_Reference
1979 -- in the identifier involved. The reason for this is
1980 -- that if we find the variable is never ever assigned
1981 -- a value then that warning is more important and
1982 -- there is no point in giving the reference warning.
1984 -- If this is an identifier, set the field directly
1986 if Nkind (N) = N_Identifier then
1987 Set_Unset_Reference (E, N);
1989 -- Otherwise it is an expanded name, so set the field
1990 -- of the actual identifier for the reference.
1993 Set_Unset_Reference (E, Selector_Name (N));
1996 end Potential_Unset_Reference;
2000 -- Indexed component or slice
2002 when N_Indexed_Component | N_Slice =>
2004 -- If prefix does not involve dereferencing an access type, then
2005 -- we know we are OK if the component type is fully initialized,
2006 -- since the component will have been set as part of the default
2009 if not Prefix_Has_Dereference (Prefix (N))
2010 and then Is_OK_Fully_Initialized
2014 -- Look at prefix in access type case, or if the component is not
2015 -- fully initialized.
2018 Check_Unset_Reference (Prefix (N));
2023 when N_Selected_Component =>
2025 Pref : constant Node_Id := Prefix (N);
2026 Ent : constant Entity_Id := Entity (Selector_Name (N));
2029 -- If prefix involves dereferencing an access type, always
2030 -- check the prefix, since the issue then is whether this
2031 -- access value is null.
2033 if Prefix_Has_Dereference (Pref) then
2036 -- Always go to prefix if no selector entity is set. Can this
2037 -- happen in the normal case? Not clear, but it definitely can
2038 -- happen in error cases.
2043 -- For a record component, check some cases where we have
2044 -- reasonable cause to consider that the component is known to
2045 -- be or probably is initialized. In this case, we don't care
2046 -- if the prefix itself was explicitly initialized.
2048 -- Discriminants are always considered initialized
2050 elsif Ekind (Ent) = E_Discriminant then
2053 -- An explicitly initialized component is certainly initialized
2055 elsif Nkind (Parent (Ent)) = N_Component_Declaration
2056 and then Present (Expression (Parent (Ent)))
2060 -- A fully initialized component is initialized
2062 elsif Is_OK_Fully_Initialized then
2066 -- If none of those cases apply, check the record type prefix
2068 Check_Unset_Reference (Pref);
2071 -- For type conversions, qualifications, or expressions with actions,
2072 -- examine the expression.
2074 when N_Type_Conversion |
2075 N_Qualified_Expression |
2076 N_Expression_With_Actions =>
2077 Check_Unset_Reference (Expression (N));
2079 -- For explicit dereference, always check prefix, which will generate
2080 -- an unset reference (since this is a case of dereferencing null).
2082 when N_Explicit_Dereference =>
2083 Check_Unset_Reference (Prefix (N));
2085 -- All other cases are not cases of an unset reference
2091 end Check_Unset_Reference;
2093 ------------------------
2094 -- Check_Unused_Withs --
2095 ------------------------
2097 procedure Check_Unused_Withs (Spec_Unit : Unit_Number_Type := No_Unit) is
2103 Munite : constant Entity_Id := Cunit_Entity (Main_Unit);
2104 -- This is needed for checking the special renaming case
2106 procedure Check_One_Unit (Unit : Unit_Number_Type);
2107 -- Subsidiary procedure, performs checks for specified unit
2109 --------------------
2110 -- Check_One_Unit --
2111 --------------------
2113 procedure Check_One_Unit (Unit : Unit_Number_Type) is
2114 Is_Visible_Renaming : Boolean := False;
2117 procedure Check_Inner_Package (Pack : Entity_Id);
2118 -- Pack is a package local to a unit in a with_clause. Both the unit
2119 -- and Pack are referenced. If none of the entities in Pack are
2120 -- referenced, then the only occurrence of Pack is in a USE clause
2121 -- or a pragma, and a warning is worthwhile as well.
2123 function Check_System_Aux return Boolean;
2124 -- Before giving a warning on a with_clause for System, check whether
2125 -- a system extension is present.
2127 function Find_Package_Renaming
2129 L : Entity_Id) return Entity_Id;
2130 -- The only reference to a context unit may be in a renaming
2131 -- declaration. If this renaming declares a visible entity, do not
2132 -- warn that the context clause could be moved to the body, because
2133 -- the renaming may be intended to re-export the unit.
2135 function Has_Visible_Entities (P : Entity_Id) return Boolean;
2136 -- This function determines if a package has any visible entities.
2137 -- True is returned if there is at least one declared visible entity,
2138 -- otherwise False is returned (e.g. case of only pragmas present).
2140 -------------------------
2141 -- Check_Inner_Package --
2142 -------------------------
2144 procedure Check_Inner_Package (Pack : Entity_Id) is
2146 Un : constant Node_Id := Sinfo.Unit (Cnode);
2148 function Check_Use_Clause (N : Node_Id) return Traverse_Result;
2149 -- If N is a use_clause for Pack, emit warning
2151 procedure Check_Use_Clauses is new
2152 Traverse_Proc (Check_Use_Clause);
2154 ----------------------
2155 -- Check_Use_Clause --
2156 ----------------------
2158 function Check_Use_Clause (N : Node_Id) return Traverse_Result is
2162 if Nkind (N) = N_Use_Package_Clause then
2163 Nam := First (Names (N));
2164 while Present (Nam) loop
2165 if Entity (Nam) = Pack then
2167 -- Suppress message if any serious errors detected
2168 -- that turn off expansion, and thus result in false
2169 -- positives for this warning.
2171 if Serious_Errors_Detected = 0 then
2172 Error_Msg_Qual_Level := 1;
2173 Error_Msg_NE -- CODEFIX
2174 ("?u?no entities of package& are referenced!",
2176 Error_Msg_Qual_Level := 0;
2185 end Check_Use_Clause;
2187 -- Start of processing for Check_Inner_Package
2190 E := First_Entity (Pack);
2191 while Present (E) loop
2192 if Referenced_Check_Spec (E) then
2199 -- No entities of the package are referenced. Check whether the
2200 -- reference to the package itself is a use clause, and if so
2201 -- place a warning on it.
2203 Check_Use_Clauses (Un);
2204 end Check_Inner_Package;
2206 ----------------------
2207 -- Check_System_Aux --
2208 ----------------------
2210 function Check_System_Aux return Boolean is
2214 if Chars (Lunit) = Name_System
2215 and then Scope (Lunit) = Standard_Standard
2216 and then Present_System_Aux
2218 Ent := First_Entity (System_Aux_Id);
2219 while Present (Ent) loop
2220 if Referenced_Check_Spec (Ent) then
2229 end Check_System_Aux;
2231 ---------------------------
2232 -- Find_Package_Renaming --
2233 ---------------------------
2235 function Find_Package_Renaming
2237 L : Entity_Id) return Entity_Id
2243 Is_Visible_Renaming := False;
2245 E1 := First_Entity (P);
2246 while Present (E1) loop
2247 if Ekind (E1) = E_Package and then Renamed_Object (E1) = L then
2248 Is_Visible_Renaming := not Is_Hidden (E1);
2251 elsif Ekind (E1) = E_Package
2252 and then No (Renamed_Object (E1))
2253 and then not Is_Generic_Instance (E1)
2255 R := Find_Package_Renaming (E1, L);
2258 Is_Visible_Renaming := not Is_Hidden (R);
2267 end Find_Package_Renaming;
2269 --------------------------
2270 -- Has_Visible_Entities --
2271 --------------------------
2273 function Has_Visible_Entities (P : Entity_Id) return Boolean is
2277 -- If unit in context is not a package, it is a subprogram that
2278 -- is not called or a generic unit that is not instantiated
2279 -- in the current unit, and warning is appropriate.
2281 if Ekind (P) /= E_Package then
2285 -- If unit comes from a limited_with clause, look for declaration
2286 -- of shadow entities.
2288 if Present (Limited_View (P)) then
2289 E := First_Entity (Limited_View (P));
2291 E := First_Entity (P);
2294 while Present (E) and then E /= First_Private_Entity (P) loop
2295 if Comes_From_Source (E) or else Present (Limited_View (P)) then
2303 end Has_Visible_Entities;
2305 -- Start of processing for Check_One_Unit
2308 Cnode := Cunit (Unit);
2310 -- Only do check in units that are part of the extended main unit.
2311 -- This is actually a necessary restriction, because in the case of
2312 -- subprogram acting as its own specification, there can be with's in
2313 -- subunits that we will not see.
2315 if not In_Extended_Main_Source_Unit (Cnode) then
2318 -- In configurable run time mode, we remove the bodies of non-inlined
2319 -- subprograms, which may lead to spurious warnings, which are
2320 -- clearly undesirable.
2322 elsif Configurable_Run_Time_Mode
2323 and then Is_Predefined_File_Name (Unit_File_Name (Unit))
2328 -- Loop through context items in this unit
2330 Item := First (Context_Items (Cnode));
2331 while Present (Item) loop
2332 if Nkind (Item) = N_With_Clause
2333 and then not Implicit_With (Item)
2334 and then In_Extended_Main_Source_Unit (Item)
2336 Lunit := Entity (Name (Item));
2338 -- Check if this unit is referenced (skip the check if this
2339 -- is explicitly marked by a pragma Unreferenced).
2341 if not Referenced (Lunit) and then not Has_Unreferenced (Lunit)
2343 -- Suppress warnings in internal units if not in -gnatg mode
2344 -- (these would be junk warnings for an application program,
2345 -- since they refer to problems in internal units).
2348 or else not Is_Internal_File_Name (Unit_File_Name (Unit))
2350 -- Here we definitely have a non-referenced unit. If it
2351 -- is the special call for a spec unit, then just set the
2352 -- flag to be read later.
2354 if Unit = Spec_Unit then
2355 Set_Unreferenced_In_Spec (Item);
2357 -- Otherwise simple unreferenced message, but skip this
2358 -- if no visible entities, because that is most likely a
2359 -- case where warning would be false positive (e.g. a
2360 -- package with only a linker options pragma and nothing
2361 -- else or a pragma elaborate with a body library task).
2363 elsif Has_Visible_Entities (Entity (Name (Item))) then
2364 Error_Msg_N -- CODEFIX
2365 ("?u?unit& is not referenced!", Name (Item));
2369 -- If main unit is a renaming of this unit, then we consider
2370 -- the with to be OK (obviously it is needed in this case).
2371 -- This may be transitive: the unit in the with_clause may
2372 -- itself be a renaming, in which case both it and the main
2373 -- unit rename the same ultimate package.
2375 elsif Present (Renamed_Entity (Munite))
2377 (Renamed_Entity (Munite) = Lunit
2378 or else Renamed_Entity (Munite) = Renamed_Entity (Lunit))
2382 -- If this unit is referenced, and it is a package, we do
2383 -- another test, to see if any of the entities in the package
2384 -- are referenced. If none of the entities are referenced, we
2385 -- still post a warning. This occurs if the only use of the
2386 -- package is in a use clause, or in a package renaming
2387 -- declaration. This check is skipped for packages that are
2388 -- renamed in a spec, since the entities in such a package are
2389 -- visible to clients via the renaming.
2391 elsif Ekind (Lunit) = E_Package
2392 and then not Renamed_In_Spec (Lunit)
2394 -- If Is_Instantiated is set, it means that the package is
2395 -- implicitly instantiated (this is the case of parent
2396 -- instance or an actual for a generic package formal), and
2397 -- this counts as a reference.
2399 if Is_Instantiated (Lunit) then
2402 -- If no entities in package, and there is a pragma
2403 -- Elaborate_Body present, then assume that this with is
2404 -- done for purposes of this elaboration.
2406 elsif No (First_Entity (Lunit))
2407 and then Has_Pragma_Elaborate_Body (Lunit)
2411 -- Otherwise see if any entities have been referenced
2414 if Limited_Present (Item) then
2415 Ent := First_Entity (Limited_View (Lunit));
2417 Ent := First_Entity (Lunit);
2421 -- No more entities, and we did not find one that was
2422 -- referenced. Means we have a definite case of a with
2423 -- none of whose entities was referenced.
2427 -- If in spec, just set the flag
2429 if Unit = Spec_Unit then
2430 Set_No_Entities_Ref_In_Spec (Item);
2432 elsif Check_System_Aux then
2435 -- Else give the warning
2438 -- Warn if we unreferenced flag set and we have
2439 -- not had serious errors. The reason we inhibit
2440 -- the message if there are errors is to prevent
2441 -- false positives from disabling expansion.
2443 if not Has_Unreferenced (Entity (Name (Item)))
2444 and then Serious_Errors_Detected = 0
2446 Error_Msg_N -- CODEFIX
2447 ("?u?no entities of & are referenced!",
2451 -- Look for renamings of this package, and flag
2452 -- them as well. If the original package has
2453 -- warnings off, we suppress the warning on the
2454 -- renaming as well.
2456 Pack := Find_Package_Renaming (Munite, Lunit);
2459 and then not Has_Warnings_Off (Lunit)
2460 and then not Has_Unreferenced (Pack)
2462 Error_Msg_NE -- CODEFIX
2463 ("?u?no entities of & are referenced!",
2464 Unit_Declaration_Node (Pack),
2471 -- Case of entity being referenced. The reference may
2472 -- come from a limited_with_clause, in which case the
2473 -- limited view of the entity carries the flag.
2475 elsif Referenced_Check_Spec (Ent)
2476 or else Referenced_As_LHS_Check_Spec (Ent)
2477 or else Referenced_As_Out_Parameter_Check_Spec (Ent)
2479 (From_Limited_With (Ent)
2480 and then Is_Incomplete_Type (Ent)
2481 and then Present (Non_Limited_View (Ent))
2482 and then Referenced (Non_Limited_View (Ent)))
2484 -- This means that the with is indeed fine, in that
2485 -- it is definitely needed somewhere, and we can
2486 -- quit worrying about this one...
2488 -- Except for one little detail: if either of the
2489 -- flags was set during spec processing, this is
2490 -- where we complain that the with could be moved
2491 -- from the spec. If the spec contains a visible
2492 -- renaming of the package, inhibit warning to move
2493 -- with_clause to body.
2495 if Ekind (Munite) = E_Package_Body then
2497 Find_Package_Renaming
2498 (Spec_Entity (Munite), Lunit);
2503 -- If a renaming is present in the spec do not warn
2504 -- because the body or child unit may depend on it.
2507 and then Renamed_Entity (Pack) = Lunit
2511 elsif Unreferenced_In_Spec (Item) then
2512 Error_Msg_N -- CODEFIX
2513 ("?u?unit& is not referenced in spec!",
2516 elsif No_Entities_Ref_In_Spec (Item) then
2517 Error_Msg_N -- CODEFIX
2518 ("?u?no entities of & are referenced in spec!",
2522 if Ekind (Ent) = E_Package then
2523 Check_Inner_Package (Ent);
2529 if not Is_Visible_Renaming then
2530 Error_Msg_N -- CODEFIX
2531 ("\?u?with clause might be moved to body!",
2537 -- Move to next entity to continue search
2545 -- For a generic package, the only interesting kind of
2546 -- reference is an instantiation, since entities cannot be
2547 -- referenced directly.
2549 elsif Is_Generic_Unit (Lunit) then
2551 -- Unit was never instantiated, set flag for case of spec
2552 -- call, or give warning for normal call.
2554 if not Is_Instantiated (Lunit) then
2555 if Unit = Spec_Unit then
2556 Set_Unreferenced_In_Spec (Item);
2558 Error_Msg_N -- CODEFIX
2559 ("?u?unit& is never instantiated!", Name (Item));
2562 -- If unit was indeed instantiated, make sure that flag is
2563 -- not set showing it was uninstantiated in the spec, and if
2564 -- so, give warning.
2566 elsif Unreferenced_In_Spec (Item) then
2568 ("?u?unit& is not instantiated in spec!", Name (Item));
2569 Error_Msg_N -- CODEFIX
2570 ("\?u?with clause can be moved to body!", Name (Item));
2579 -- Start of processing for Check_Unused_Withs
2582 -- Immediate return if no semantics or warning flag not set
2584 if not Opt.Check_Withs or else Operating_Mode = Check_Syntax then
2588 Process_Deferred_References;
2590 -- Flag any unused with clauses. For a subunit, check only the units
2591 -- in its context, not those of the parent, which may be needed by other
2592 -- subunits. We will get the full warnings when we compile the parent,
2593 -- but the following is helpful when compiling a subunit by itself.
2595 if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
2596 if Current_Sem_Unit = Main_Unit then
2597 Check_One_Unit (Main_Unit);
2603 -- Process specified units
2605 if Spec_Unit = No_Unit then
2607 -- For main call, check all units
2609 for Unit in Main_Unit .. Last_Unit loop
2610 Check_One_Unit (Unit);
2614 -- For call for spec, check only the spec
2616 Check_One_Unit (Spec_Unit);
2618 end Check_Unused_Withs;
2620 ---------------------------------
2621 -- Generic_Package_Spec_Entity --
2622 ---------------------------------
2624 function Generic_Package_Spec_Entity (E : Entity_Id) return Boolean is
2628 if Is_Package_Body_Entity (E) then
2634 if S = Standard_Standard then
2637 elsif Ekind (S) = E_Generic_Package then
2640 elsif Ekind (S) = E_Package then
2648 end Generic_Package_Spec_Entity;
2650 ----------------------
2651 -- Goto_Spec_Entity --
2652 ----------------------
2654 function Goto_Spec_Entity (E : Entity_Id) return Entity_Id is
2656 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2657 return Spec_Entity (E);
2661 end Goto_Spec_Entity;
2663 --------------------------------------
2664 -- Has_Pragma_Unmodified_Check_Spec --
2665 --------------------------------------
2667 function Has_Pragma_Unmodified_Check_Spec
2668 (E : Entity_Id) return Boolean
2671 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2673 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2674 -- to mess with Unmodified flags on both body and spec entities.
2676 return Has_Unmodified (E)
2678 Has_Unmodified (Spec_Entity (E));
2681 return Has_Unmodified (E);
2683 end Has_Pragma_Unmodified_Check_Spec;
2685 ----------------------------------------
2686 -- Has_Pragma_Unreferenced_Check_Spec --
2687 ----------------------------------------
2689 function Has_Pragma_Unreferenced_Check_Spec
2690 (E : Entity_Id) return Boolean
2693 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2695 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2696 -- to mess with flags on both entities.
2698 return Has_Unreferenced (E)
2700 Has_Unreferenced (Spec_Entity (E));
2703 return Has_Unreferenced (E);
2705 end Has_Pragma_Unreferenced_Check_Spec;
2711 procedure Initialize is
2713 Warnings_Off_Pragmas.Init;
2714 Unreferenced_Entities.Init;
2715 In_Out_Warnings.Init;
2718 ------------------------------------
2719 -- Never_Set_In_Source_Check_Spec --
2720 ------------------------------------
2722 function Never_Set_In_Source_Check_Spec (E : Entity_Id) return Boolean is
2724 if Is_Formal (E) and then Present (Spec_Entity (E)) then
2725 return Never_Set_In_Source (E)
2727 Never_Set_In_Source (Spec_Entity (E));
2729 return Never_Set_In_Source (E);
2731 end Never_Set_In_Source_Check_Spec;
2733 -------------------------------------
2734 -- Operand_Has_Warnings_Suppressed --
2735 -------------------------------------
2737 function Operand_Has_Warnings_Suppressed (N : Node_Id) return Boolean is
2739 function Check_For_Warnings (N : Node_Id) return Traverse_Result;
2740 -- Function used to check one node to see if it is or was originally
2741 -- a reference to an entity for which Warnings are off. If so, Abandon
2742 -- is returned, otherwise OK_Orig is returned to continue the traversal
2743 -- of the original expression.
2745 function Traverse is new Traverse_Func (Check_For_Warnings);
2746 -- Function used to traverse tree looking for warnings
2748 ------------------------
2749 -- Check_For_Warnings --
2750 ------------------------
2752 function Check_For_Warnings (N : Node_Id) return Traverse_Result is
2753 R : constant Node_Id := Original_Node (N);
2756 if Nkind (R) in N_Has_Entity
2757 and then Present (Entity (R))
2758 and then Has_Warnings_Off (Entity (R))
2764 end Check_For_Warnings;
2766 -- Start of processing for Operand_Has_Warnings_Suppressed
2769 return Traverse (N) = Abandon;
2771 -- If any exception occurs, then something has gone wrong, and this is
2772 -- only a minor aesthetic issue anyway, so just say we did not find what
2773 -- we are looking for, rather than blow up.
2778 end Operand_Has_Warnings_Suppressed;
2780 -----------------------------------------
2781 -- Output_Non_Modified_In_Out_Warnings --
2782 -----------------------------------------
2784 procedure Output_Non_Modified_In_Out_Warnings is
2786 function No_Warn_On_In_Out (E : Entity_Id) return Boolean;
2787 -- Given a formal parameter entity E, determines if there is a reason to
2788 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2789 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2790 -- if we have seen the address of the subprogram being taken, or if the
2791 -- subprogram is used as a generic actual (in the latter cases the
2792 -- context may force use of IN OUT, even if the parameter is not
2793 -- modifies for this particular case.
2795 -----------------------
2796 -- No_Warn_On_In_Out --
2797 -----------------------
2799 function No_Warn_On_In_Out (E : Entity_Id) return Boolean is
2800 S : constant Entity_Id := Scope (E);
2801 SE : constant Entity_Id := Spec_Entity (E);
2804 -- Do not warn if address is taken, since funny business may be going
2805 -- on in treating the parameter indirectly as IN OUT.
2807 if Address_Taken (S)
2808 or else (Present (SE) and then Address_Taken (Scope (SE)))
2812 -- Do not warn if used as a generic actual, since the generic may be
2813 -- what is forcing the use of an "unnecessary" IN OUT.
2815 elsif Used_As_Generic_Actual (S)
2816 or else (Present (SE) and then Used_As_Generic_Actual (Scope (SE)))
2820 -- Else test warnings off
2822 elsif Warnings_Off_Check_Spec (S) then
2825 -- All tests for suppressing warning failed
2830 end No_Warn_On_In_Out;
2832 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2835 -- Loop through entities for which a warning may be needed
2837 for J in In_Out_Warnings.First .. In_Out_Warnings.Last loop
2839 E1 : constant Entity_Id := In_Out_Warnings.Table (J);
2842 -- Suppress warning in specific cases (see details in comments for
2843 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2845 if Has_Pragma_Unmodified_Check_Spec (E1)
2846 or else No_Warn_On_In_Out (E1)
2850 -- Here we generate the warning
2853 -- If -gnatwc is set then output message that we could be IN
2855 if not Is_Trivial_Subprogram (Scope (E1)) then
2856 if Warn_On_Constant then
2858 ("?u?formal parameter & is not modified!", E1);
2860 ("\?u?mode could be IN instead of `IN OUT`!", E1);
2862 -- We do not generate warnings for IN OUT parameters
2863 -- unless we have at least -gnatwu. This is deliberately
2864 -- inconsistent with the treatment of variables, but
2865 -- otherwise we get too many unexpected warnings in
2868 elsif Check_Unreferenced then
2870 ("?u?formal parameter& is read but "
2871 & "never assigned!", E1);
2875 -- Kill any other warnings on this entity, since this is the
2876 -- one that should dominate any other unreferenced warning.
2878 Set_Warnings_Off (E1);
2882 end Output_Non_Modified_In_Out_Warnings;
2884 ----------------------------------------
2885 -- Output_Obsolescent_Entity_Warnings --
2886 ----------------------------------------
2888 procedure Output_Obsolescent_Entity_Warnings (N : Node_Id; E : Entity_Id) is
2889 P : constant Node_Id := Parent (N);
2895 -- Do not output message if we are the scope of standard. This means
2896 -- we have a reference from a context clause from when it is originally
2897 -- processed, and that's too early to tell whether it is an obsolescent
2898 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2899 -- sure that we have a later call when the scope is available. This test
2900 -- also eliminates all messages for use clauses, which is fine (we do
2901 -- not want messages for use clauses, since they are always redundant
2902 -- with respect to the associated with clause).
2904 if S = Standard_Standard then
2908 -- Do not output message if we are in scope of an obsolescent package
2912 if Is_Obsolescent (S) then
2917 exit when S = Standard_Standard;
2920 -- Here we will output the message
2922 Error_Msg_Sloc := Sloc (E);
2924 -- Case of with clause
2926 if Nkind (P) = N_With_Clause then
2927 if Ekind (E) = E_Package then
2929 ("?j?with of obsolescent package& declared#", N, E);
2930 elsif Ekind (E) = E_Procedure then
2932 ("?j?with of obsolescent procedure& declared#", N, E);
2935 ("??with of obsolescent function& declared#", N, E);
2938 -- If we do not have a with clause, then ignore any reference to an
2939 -- obsolescent package name. We only want to give the one warning of
2940 -- withing the package, not one each time it is used to qualify.
2942 elsif Ekind (E) = E_Package then
2945 -- Procedure call statement
2947 elsif Nkind (P) = N_Procedure_Call_Statement then
2949 ("??call to obsolescent procedure& declared#", N, E);
2953 elsif Nkind (P) = N_Function_Call then
2955 ("??call to obsolescent function& declared#", N, E);
2957 -- Reference to obsolescent type
2959 elsif Is_Type (E) then
2961 ("??reference to obsolescent type& declared#", N, E);
2963 -- Reference to obsolescent component
2965 elsif Ekind_In (E, E_Component, E_Discriminant) then
2967 ("??reference to obsolescent component& declared#", N, E);
2969 -- Reference to obsolescent variable
2971 elsif Ekind (E) = E_Variable then
2973 ("??reference to obsolescent variable& declared#", N, E);
2975 -- Reference to obsolescent constant
2977 elsif Ekind (E) = E_Constant or else Ekind (E) in Named_Kind then
2979 ("??reference to obsolescent constant& declared#", N, E);
2981 -- Reference to obsolescent enumeration literal
2983 elsif Ekind (E) = E_Enumeration_Literal then
2985 ("??reference to obsolescent enumeration literal& declared#", N, E);
2987 -- Generic message for any other case we missed
2991 ("??reference to obsolescent entity& declared#", N, E);
2994 -- Output additional warning if present
2996 for J in Obsolescent_Warnings.First .. Obsolescent_Warnings.Last loop
2997 if Obsolescent_Warnings.Table (J).Ent = E then
2998 String_To_Name_Buffer (Obsolescent_Warnings.Table (J).Msg);
2999 Error_Msg_Strlen := Name_Len;
3000 Error_Msg_String (1 .. Name_Len) := Name_Buffer (1 .. Name_Len);
3001 Error_Msg_N ("\\??~", N);
3005 end Output_Obsolescent_Entity_Warnings;
3007 ----------------------------------
3008 -- Output_Unreferenced_Messages --
3009 ----------------------------------
3011 procedure Output_Unreferenced_Messages is
3013 for J in Unreferenced_Entities.First ..
3014 Unreferenced_Entities.Last
3016 Warn_On_Unreferenced_Entity (Unreferenced_Entities.Table (J));
3018 end Output_Unreferenced_Messages;
3020 -----------------------------------------
3021 -- Output_Unused_Warnings_Off_Warnings --
3022 -----------------------------------------
3024 procedure Output_Unused_Warnings_Off_Warnings is
3026 for J in Warnings_Off_Pragmas.First .. Warnings_Off_Pragmas.Last loop
3028 Wentry : Warnings_Off_Entry renames Warnings_Off_Pragmas.Table (J);
3029 N : Node_Id renames Wentry.N;
3030 E : Node_Id renames Wentry.E;
3033 -- Turn off Warnings_Off, or we won't get the warning
3035 Set_Warnings_Off (E, False);
3037 -- Nothing to do if pragma was used to suppress a general warning
3039 if Warnings_Off_Used (E) then
3042 -- If pragma was used both in unmodified and unreferenced contexts
3043 -- then that's as good as the general case, no warning.
3045 elsif Warnings_Off_Used_Unmodified (E)
3047 Warnings_Off_Used_Unreferenced (E)
3051 -- Used only in context where Unmodified would have worked
3053 elsif Warnings_Off_Used_Unmodified (E) then
3055 ("?W?could use Unmodified instead of "
3056 & "Warnings Off for &", Pragma_Identifier (N), E);
3058 -- Used only in context where Unreferenced would have worked
3060 elsif Warnings_Off_Used_Unreferenced (E) then
3062 ("?W?could use Unreferenced instead of "
3063 & "Warnings Off for &", Pragma_Identifier (N), E);
3069 ("?W?pragma Warnings Off for & unused, "
3070 & "could be omitted", N, E);
3074 end Output_Unused_Warnings_Off_Warnings;
3076 ---------------------------
3077 -- Referenced_Check_Spec --
3078 ---------------------------
3080 function Referenced_Check_Spec (E : Entity_Id) return Boolean is
3082 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3083 return Referenced (E) or else Referenced (Spec_Entity (E));
3085 return Referenced (E);
3087 end Referenced_Check_Spec;
3089 ----------------------------------
3090 -- Referenced_As_LHS_Check_Spec --
3091 ----------------------------------
3093 function Referenced_As_LHS_Check_Spec (E : Entity_Id) return Boolean is
3095 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3096 return Referenced_As_LHS (E)
3097 or else Referenced_As_LHS (Spec_Entity (E));
3099 return Referenced_As_LHS (E);
3101 end Referenced_As_LHS_Check_Spec;
3103 --------------------------------------------
3104 -- Referenced_As_Out_Parameter_Check_Spec --
3105 --------------------------------------------
3107 function Referenced_As_Out_Parameter_Check_Spec
3108 (E : Entity_Id) return Boolean
3111 if Is_Formal (E) and then Present (Spec_Entity (E)) then
3112 return Referenced_As_Out_Parameter (E)
3113 or else Referenced_As_Out_Parameter (Spec_Entity (E));
3115 return Referenced_As_Out_Parameter (E);
3117 end Referenced_As_Out_Parameter_Check_Spec;
3119 -----------------------------
3120 -- Warn_On_Known_Condition --
3121 -----------------------------
3123 procedure Warn_On_Known_Condition (C : Node_Id) is
3125 Orig : constant Node_Id := Original_Node (C);
3126 Test_Result : Boolean;
3128 function Is_Known_Branch return Boolean;
3129 -- If the type of the condition is Boolean, the constant value of the
3130 -- condition is a boolean literal. If the type is a derived boolean
3131 -- type, the constant is wrapped in a type conversion of the derived
3132 -- literal. If the value of the condition is not a literal, no warnings
3133 -- can be produced. This function returns True if the result can be
3134 -- determined, and Test_Result is set True/False accordingly. Otherwise
3135 -- False is returned, and Test_Result is unchanged.
3137 procedure Track (N : Node_Id; Loc : Node_Id);
3138 -- Adds continuation warning(s) pointing to reason (assignment or test)
3139 -- for the operand of the conditional having a known value (or at least
3140 -- enough is known about the value to issue the warning). N is the node
3141 -- which is judged to have a known value. Loc is the warning location.
3143 ---------------------
3144 -- Is_Known_Branch --
3145 ---------------------
3147 function Is_Known_Branch return Boolean is
3149 if Etype (C) = Standard_Boolean
3150 and then Is_Entity_Name (C)
3152 (Entity (C) = Standard_False or else Entity (C) = Standard_True)
3154 Test_Result := Entity (C) = Standard_True;
3157 elsif Is_Boolean_Type (Etype (C))
3158 and then Nkind (C) = N_Unchecked_Type_Conversion
3159 and then Is_Entity_Name (Expression (C))
3160 and then Ekind (Entity (Expression (C))) = E_Enumeration_Literal
3163 Chars (Entity (Expression (C))) = Chars (Standard_True);
3169 end Is_Known_Branch;
3175 procedure Track (N : Node_Id; Loc : Node_Id) is
3176 Nod : constant Node_Id := Original_Node (N);
3179 if Nkind (Nod) in N_Op_Compare then
3180 Track (Left_Opnd (Nod), Loc);
3181 Track (Right_Opnd (Nod), Loc);
3183 elsif Is_Entity_Name (Nod) and then Is_Object (Entity (Nod)) then
3185 CV : constant Node_Id := Current_Value (Entity (Nod));
3188 if Present (CV) then
3189 Error_Msg_Sloc := Sloc (CV);
3191 if Nkind (CV) not in N_Subexpr then
3192 Error_Msg_N ("\\??(see test #)", Loc);
3194 elsif Nkind (Parent (CV)) =
3195 N_Case_Statement_Alternative
3197 Error_Msg_N ("\\??(see case alternative #)", Loc);
3200 Error_Msg_N ("\\??(see assignment #)", Loc);
3207 -- Start of processing for Warn_On_Known_Condition
3210 -- Adjust SCO condition if from source
3213 and then Comes_From_Source (Orig)
3214 and then Is_Known_Branch
3220 Atrue := Test_Result;
3222 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not then
3226 Set_SCO_Condition (Orig, Atrue);
3230 -- Argument replacement in an inlined body can make conditions static.
3231 -- Do not emit warnings in this case.
3233 if In_Inlined_Body then
3237 if Constant_Condition_Warnings
3238 and then Is_Known_Branch
3239 and then Comes_From_Source (Orig)
3240 and then not In_Instance
3242 -- Don't warn if comparison of result of attribute against a constant
3243 -- value, since this is likely legitimate conditional compilation.
3245 if Nkind (Orig) in N_Op_Compare
3246 and then Compile_Time_Known_Value (Right_Opnd (Orig))
3247 and then Nkind (Original_Node (Left_Opnd (Orig))) =
3248 N_Attribute_Reference
3253 -- See if this is in a statement or a declaration
3257 -- If tree is not attached, do not issue warning (this is very
3258 -- peculiar, and probably arises from some other error condition)
3263 -- If we are in a declaration, then no warning, since in practice
3264 -- conditionals in declarations are used for intended tests which
3265 -- may be known at compile time, e.g. things like
3267 -- x : constant Integer := 2 + (Word'Size = 32);
3269 -- And a warning is annoying in such cases
3271 elsif Nkind (P) in N_Declaration
3273 Nkind (P) in N_Later_Decl_Item
3277 -- Don't warn in assert or check pragma, since presumably tests in
3278 -- such a context are very definitely intended, and might well be
3279 -- known at compile time. Note that we have to test the original
3280 -- node, since assert pragmas get rewritten at analysis time.
3282 elsif Nkind (Original_Node (P)) = N_Pragma
3283 and then Nam_In (Pragma_Name (Original_Node (P)), Name_Assert,
3289 exit when Is_Statement (P);
3293 -- Here we issue the warning unless some sub-operand has warnings
3294 -- set off, in which case we suppress the warning for the node. If
3295 -- the original expression is an inequality, it has been expanded
3296 -- into a negation, and the value of the original expression is the
3297 -- negation of the equality. If the expression is an entity that
3298 -- appears within a negation, it is clearer to flag the negation
3299 -- itself, and report on its constant value.
3301 if not Operand_Has_Warnings_Suppressed (C) then
3303 True_Branch : Boolean := Test_Result;
3304 Cond : Node_Id := C;
3307 if Present (Parent (C)) and then Nkind (Parent (C)) = N_Op_Not
3309 True_Branch := not True_Branch;
3314 if Is_Entity_Name (Original_Node (C))
3315 and then Nkind (Cond) /= N_Op_Not
3318 ("object & is always True?c?", Cond, Original_Node (C));
3319 Track (Original_Node (C), Cond);
3322 Error_Msg_N ("condition is always True?c?", Cond);
3327 Error_Msg_N ("condition is always False?c?", Cond);
3333 end Warn_On_Known_Condition;
3335 ---------------------------------------
3336 -- Warn_On_Modified_As_Out_Parameter --
3337 ---------------------------------------
3339 function Warn_On_Modified_As_Out_Parameter (E : Entity_Id) return Boolean is
3342 (Warn_On_Modified_Unread and then Is_Only_Out_Parameter (E))
3343 or else Warn_On_All_Unread_Out_Parameters;
3344 end Warn_On_Modified_As_Out_Parameter;
3346 ---------------------------------
3347 -- Warn_On_Overlapping_Actuals --
3348 ---------------------------------
3350 procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
3351 Act1, Act2 : Node_Id;
3352 Form1, Form2 : Entity_Id;
3354 function Is_Covered_Formal (Formal : Node_Id) return Boolean;
3355 -- Return True if Formal is covered by the rule
3357 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean;
3358 -- Two names are known to refer to the same object if the two names
3359 -- are known to denote the same object; or one of the names is a
3360 -- selected_component, indexed_component, or slice and its prefix is
3361 -- known to refer to the same object as the other name; or one of the
3362 -- two names statically denotes a renaming declaration whose renamed
3363 -- object_name is known to refer to the same object as the other name
3364 -- (RM 6.4.1(6.11/3))
3366 -----------------------
3367 -- Refer_Same_Object --
3368 -----------------------
3370 function Refer_Same_Object (Act1, Act2 : Node_Id) return Boolean is
3372 return Denotes_Same_Object (Act1, Act2)
3373 or else Denotes_Same_Prefix (Act1, Act2);
3374 end Refer_Same_Object;
3376 -----------------------
3377 -- Is_Covered_Formal --
3378 -----------------------
3380 function Is_Covered_Formal (Formal : Node_Id) return Boolean is
3383 Ekind_In (Formal, E_Out_Parameter, E_In_Out_Parameter)
3384 and then (Is_Elementary_Type (Etype (Formal))
3385 or else Is_Record_Type (Etype (Formal))
3386 or else Is_Array_Type (Etype (Formal)));
3387 end Is_Covered_Formal;
3390 if Ada_Version < Ada_2012 and then not Warn_On_Overlap then
3394 -- Exclude calls rewritten as enumeration literals
3396 if Nkind (N) not in N_Subprogram_Call
3397 and then Nkind (N) /= N_Entry_Call_Statement
3402 -- If a call C has two or more parameters of mode in out or out that are
3403 -- of an elementary type, then the call is legal only if for each name
3404 -- N that is passed as a parameter of mode in out or out to the call C,
3405 -- there is no other name among the other parameters of mode in out or
3406 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3408 -- If appropriate warning switch is set, we also report warnings on
3409 -- overlapping parameters that are record types or array types.
3411 Form1 := First_Formal (Subp);
3412 Act1 := First_Actual (N);
3413 while Present (Form1) and then Present (Act1) loop
3414 if Is_Covered_Formal (Form1) then
3415 Form2 := First_Formal (Subp);
3416 Act2 := First_Actual (N);
3417 while Present (Form2) and then Present (Act2) loop
3419 and then Is_Covered_Formal (Form2)
3420 and then Refer_Same_Object (Act1, Act2)
3422 -- Guard against previous errors
3425 or else No (Etype (Act1))
3426 or else No (Etype (Act2))
3430 -- If the actual is a function call in prefix notation,
3431 -- there is no real overlap.
3433 elsif Nkind (Act2) = N_Function_Call then
3436 -- If type is not by-copy, assume that aliasing is intended
3439 Present (Underlying_Type (Etype (Form1)))
3441 (Is_By_Reference_Type (Underlying_Type (Etype (Form1)))
3443 Convention (Underlying_Type (Etype (Form1))) =
3444 Convention_Ada_Pass_By_Reference)
3448 -- Under Ada 2012 we only report warnings on overlapping
3449 -- arrays and record types if switch is set.
3451 elsif Ada_Version >= Ada_2012
3452 and then not Is_Elementary_Type (Etype (Form1))
3453 and then not Warn_On_Overlap
3457 -- Here we may need to issue overlap message
3462 -- Overlap checking is an error only in Ada 2012. For
3463 -- earlier versions of Ada, this is a warning.
3465 Ada_Version < Ada_2012
3467 -- Overlap is only illegal in Ada 2012 in the case of
3468 -- elementary types (passed by copy). For other types,
3469 -- we always have a warning in all Ada versions.
3471 or else not Is_Elementary_Type (Etype (Form1))
3473 -- Finally, debug flag -gnatd.E changes the error to a
3474 -- warning even in Ada 2012 mode.
3476 or else Error_To_Warning;
3483 -- Find matching actual
3485 Act := First_Actual (N);
3486 Form := First_Formal (Subp);
3487 while Act /= Act2 loop
3492 if Is_Elementary_Type (Etype (Act1))
3493 and then Ekind (Form2) = E_In_Parameter
3495 null; -- No real aliasing
3497 elsif Is_Elementary_Type (Etype (Act2))
3498 and then Ekind (Form2) = E_In_Parameter
3502 -- If the call was written in prefix notation, and
3503 -- thus its prefix before rewriting was a selected
3504 -- component, count only visible actuals in the call.
3506 elsif Is_Entity_Name (First_Actual (N))
3507 and then Nkind (Original_Node (N)) = Nkind (N)
3508 and then Nkind (Name (Original_Node (N))) =
3509 N_Selected_Component
3511 Is_Entity_Name (Prefix (Name (Original_Node (N))))
3513 Entity (Prefix (Name (Original_Node (N)))) =
3514 Entity (First_Actual (N))
3516 if Act1 = First_Actual (N) then
3518 ("<<`IN OUT` prefix overlaps with "
3519 & "actual for&", Act1, Form);
3522 -- For greater clarity, give name of formal
3524 Error_Msg_Node_2 := Form;
3526 ("<<writable actual for & overlaps with "
3527 & "actual for&", Act1, Form);
3531 -- For greater clarity, give name of formal
3533 Error_Msg_Node_2 := Form;
3535 -- This is one of the messages
3538 ("<<writable actual for & overlaps with "
3539 & "actual for&", Act1, Form1);
3547 Next_Formal (Form2);
3552 Next_Formal (Form1);
3555 end Warn_On_Overlapping_Actuals;
3557 ------------------------------
3558 -- Warn_On_Suspicious_Index --
3559 ------------------------------
3561 procedure Warn_On_Suspicious_Index (Name : Entity_Id; X : Node_Id) is
3564 -- Set to lower bound for a suspicious type
3567 -- Entity for array reference
3572 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean;
3573 -- Tests to see if Typ is a type for which we may have a suspicious
3574 -- index, namely an unconstrained array type, whose lower bound is
3575 -- either zero or one. If so, True is returned, and Low_Bound is set
3576 -- to this lower bound. If not, False is returned, and Low_Bound is
3577 -- undefined on return.
3579 -- For now, we limit this to standard string types, so any other
3580 -- unconstrained types return False. We may change our minds on this
3581 -- later on, but strings seem the most important case.
3583 procedure Test_Suspicious_Index;
3584 -- Test if index is of suspicious type and if so, generate warning
3586 ------------------------
3587 -- Is_Suspicious_Type --
3588 ------------------------
3590 function Is_Suspicious_Type (Typ : Entity_Id) return Boolean is
3594 if Is_Array_Type (Typ)
3595 and then not Is_Constrained (Typ)
3596 and then Number_Dimensions (Typ) = 1
3597 and then (Root_Type (Typ) = Standard_String
3599 Root_Type (Typ) = Standard_Wide_String
3601 Root_Type (Typ) = Standard_Wide_Wide_String)
3602 and then not Has_Warnings_Off (Typ)
3604 LB := Type_Low_Bound (Etype (First_Index (Typ)));
3606 if Compile_Time_Known_Value (LB) then
3607 Low_Bound := Expr_Value (LB);
3608 return Low_Bound = Uint_0 or else Low_Bound = Uint_1;
3613 end Is_Suspicious_Type;
3615 ---------------------------
3616 -- Test_Suspicious_Index --
3617 ---------------------------
3619 procedure Test_Suspicious_Index is
3621 function Length_Reference (N : Node_Id) return Boolean;
3622 -- Check if node N is of the form Name'Length
3625 -- Generate first warning line
3627 ----------------------
3628 -- Length_Reference --
3629 ----------------------
3631 function Length_Reference (N : Node_Id) return Boolean is
3632 R : constant Node_Id := Original_Node (N);
3635 Nkind (R) = N_Attribute_Reference
3636 and then Attribute_Name (R) = Name_Length
3637 and then Is_Entity_Name (Prefix (R))
3638 and then Entity (Prefix (R)) = Ent;
3639 end Length_Reference;
3647 Error_Msg_Uint_1 := Low_Bound;
3648 Error_Msg_FE -- CODEFIX
3649 ("?w?index for& may assume lower bound of^", X, Ent);
3652 -- Start of processing for Test_Suspicious_Index
3655 -- Nothing to do if subscript does not come from source (we don't
3656 -- want to give garbage warnings on compiler expanded code, e.g. the
3657 -- loops generated for slice assignments. Such junk warnings would
3658 -- be placed on source constructs with no subscript in sight).
3660 if not Comes_From_Source (Original_Node (X)) then
3664 -- Case where subscript is a constant integer
3666 if Nkind (X) = N_Integer_Literal then
3669 -- Case where original form of subscript is an integer literal
3671 if Nkind (Original_Node (X)) = N_Integer_Literal then
3672 if Intval (X) = Low_Bound then
3673 Error_Msg_FE -- CODEFIX
3674 ("\?w?suggested replacement: `&''First`", X, Ent);
3676 Error_Msg_Uint_1 := Intval (X) - Low_Bound;
3677 Error_Msg_FE -- CODEFIX
3678 ("\?w?suggested replacement: `&''First + ^`", X, Ent);
3682 -- Case where original form of subscript is more complex
3685 -- Build string X'First - 1 + expression where the expression
3686 -- is the original subscript. If the expression starts with "1
3687 -- + ", then the "- 1 + 1" is elided.
3689 Error_Msg_String (1 .. 13) := "'First - 1 + ";
3690 Error_Msg_Strlen := 13;
3693 Sref : Source_Ptr := Sloc (First_Node (Original_Node (X)));
3694 Tref : constant Source_Buffer_Ptr :=
3695 Source_Text (Get_Source_File_Index (Sref));
3696 -- Tref (Sref) is used to scan the subscript
3699 -- Parentheses counter when scanning subscript
3702 -- Tref (Sref) points to start of subscript
3704 -- Elide - 1 if subscript starts with 1 +
3706 if Tref (Sref .. Sref + 2) = "1 +" then
3707 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3710 elsif Tref (Sref .. Sref + 1) = "1+" then
3711 Error_Msg_Strlen := Error_Msg_Strlen - 6;
3715 -- Now we will copy the subscript to the string buffer
3719 -- Count parens, exit if terminating right paren. Note
3720 -- check to ignore paren appearing as character literal.
3722 if Tref (Sref + 1) = '''
3724 Tref (Sref - 1) = '''
3728 if Tref (Sref) = '(' then
3730 elsif Tref (Sref) = ')' then
3736 -- Done if terminating double dot (slice case)
3739 and then (Tref (Sref .. Sref + 1) = ".."
3741 Tref (Sref .. Sref + 2) = " ..");
3743 -- Quit if we have hit EOF character, something wrong
3745 if Tref (Sref) = EOF then
3749 -- String literals are too much of a pain to handle
3751 if Tref (Sref) = '"' or else Tref (Sref) = '%' then
3755 -- If we have a 'Range reference, then this is a case
3756 -- where we cannot easily give a replacement. Don't try.
3758 if Tref (Sref .. Sref + 4) = "range"
3759 and then Tref (Sref - 1) < 'A'
3760 and then Tref (Sref + 5) < 'A'
3765 -- Else store next character
3767 Error_Msg_Strlen := Error_Msg_Strlen + 1;
3768 Error_Msg_String (Error_Msg_Strlen) := Tref (Sref);
3771 -- If we get more than 40 characters then the expression
3772 -- is too long to copy, or something has gone wrong. In
3773 -- either case, just skip the attempt at a suggested fix.
3775 if Error_Msg_Strlen > 40 then
3781 -- Replacement subscript is now in string buffer
3783 Error_Msg_FE -- CODEFIX
3784 ("\?w?suggested replacement: `&~`", Original_Node (X), Ent);
3787 -- Case where subscript is of the form X'Length
3789 elsif Length_Reference (X) then
3791 Error_Msg_Node_2 := Ent;
3793 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3796 -- Case where subscript is of the form X'Length - expression
3798 elsif Nkind (X) = N_Op_Subtract
3799 and then Length_Reference (Left_Opnd (X))
3802 Error_Msg_Node_2 := Ent;
3804 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3805 Left_Opnd (X), Ent);
3807 end Test_Suspicious_Index;
3809 -- Start of processing for Warn_On_Suspicious_Index
3812 -- Only process if warnings activated
3814 if Warn_On_Assumed_Low_Bound then
3816 -- Test if array is simple entity name
3818 if Is_Entity_Name (Name) then
3820 -- Test if array is parameter of unconstrained string type
3822 Ent := Entity (Name);
3826 and then Is_Suspicious_Type (Typ)
3827 and then not Low_Bound_Tested (Ent)
3829 Test_Suspicious_Index;
3833 end Warn_On_Suspicious_Index;
3835 --------------------------------------
3836 -- Warn_On_Unassigned_Out_Parameter --
3837 --------------------------------------
3839 procedure Warn_On_Unassigned_Out_Parameter
3840 (Return_Node : Node_Id;
3841 Scope_Id : Entity_Id)
3847 -- Ignore if procedure or return statement does not come from source
3849 if not Comes_From_Source (Scope_Id)
3850 or else not Comes_From_Source (Return_Node)
3855 -- Loop through formals
3857 Form := First_Formal (Scope_Id);
3858 while Present (Form) loop
3860 -- We are only interested in OUT parameters that come from source
3861 -- and are never set in the source, and furthermore only in scalars
3862 -- since non-scalars generate too many false positives.
3864 if Ekind (Form) = E_Out_Parameter
3865 and then Never_Set_In_Source_Check_Spec (Form)
3866 and then Is_Scalar_Type (Etype (Form))
3867 and then not Present (Unset_Reference (Form))
3869 -- Before we issue the warning, an add ad hoc defence against the
3870 -- most common case of false positives with this warning which is
3871 -- the case where there is a Boolean OUT parameter that has been
3872 -- set, and whose meaning is "ignore the values of the other
3873 -- parameters". We can't of course reliably tell this case at
3874 -- compile time, but the following test kills a lot of false
3875 -- positives, without generating a significant number of false
3876 -- negatives (missed real warnings).
3878 Form2 := First_Formal (Scope_Id);
3879 while Present (Form2) loop
3880 if Ekind (Form2) = E_Out_Parameter
3881 and then Root_Type (Etype (Form2)) = Standard_Boolean
3882 and then not Never_Set_In_Source_Check_Spec (Form2)
3887 Next_Formal (Form2);
3890 -- Here all conditions are met, record possible unset reference
3892 Set_Unset_Reference (Form, Return_Node);
3897 end Warn_On_Unassigned_Out_Parameter;
3899 ---------------------------------
3900 -- Warn_On_Unreferenced_Entity --
3901 ---------------------------------
3903 procedure Warn_On_Unreferenced_Entity
3904 (Spec_E : Entity_Id;
3905 Body_E : Entity_Id := Empty)
3907 E : Entity_Id := Spec_E;
3910 if not Referenced_Check_Spec (E)
3911 and then not Has_Pragma_Unreferenced_Check_Spec (E)
3912 and then not Warnings_Off_Check_Spec (E)
3913 and then not Is_Junk_Name (Chars (Spec_E))
3918 -- Case of variable that is assigned but not read. We suppress
3919 -- the message if the variable is volatile, has an address
3920 -- clause, is aliased, or is a renaming, or is imported.
3922 if Referenced_As_LHS_Check_Spec (E)
3923 and then No (Address_Clause (E))
3924 and then not Is_Volatile (E)
3926 if Warn_On_Modified_Unread
3927 and then not Is_Imported (E)
3928 and then not Is_Aliased (E)
3929 and then No (Renamed_Object (E))
3931 if not Has_Pragma_Unmodified_Check_Spec (E) then
3932 Error_Msg_N -- CODEFIX
3933 ("?u?variable & is assigned but never read!", E);
3936 Set_Last_Assignment (E, Empty);
3939 -- Normal case of neither assigned nor read (exclude variables
3940 -- referenced as out parameters, since we already generated
3941 -- appropriate warnings at the call point in this case).
3943 elsif not Referenced_As_Out_Parameter (E) then
3945 -- We suppress the message for types for which a valid
3946 -- pragma Unreferenced_Objects has been given, otherwise
3947 -- we go ahead and give the message.
3949 if not Has_Pragma_Unreferenced_Objects (Etype (E)) then
3951 -- Distinguish renamed case in message
3953 if Present (Renamed_Object (E))
3954 and then Comes_From_Source (Renamed_Object (E))
3956 Error_Msg_N -- CODEFIX
3957 ("?u?renamed variable & is not referenced!", E);
3959 Error_Msg_N -- CODEFIX
3960 ("?u?variable & is not referenced!", E);
3966 if Present (Renamed_Object (E))
3967 and then Comes_From_Source (Renamed_Object (E))
3969 Error_Msg_N -- CODEFIX
3970 ("?u?renamed constant & is not referenced!", E);
3972 Error_Msg_N -- CODEFIX
3973 ("?u?constant & is not referenced!", E);
3976 when E_In_Parameter |
3977 E_In_Out_Parameter =>
3979 -- Do not emit message for formals of a renaming, because
3980 -- they are never referenced explicitly.
3982 if Nkind (Original_Node (Unit_Declaration_Node (Scope (E)))) /=
3983 N_Subprogram_Renaming_Declaration
3985 -- Suppress this message for an IN OUT parameter of a
3986 -- non-scalar type, since it is normal to have only an
3987 -- assignment in such a case.
3989 if Ekind (E) = E_In_Parameter
3990 or else not Referenced_As_LHS_Check_Spec (E)
3991 or else Is_Scalar_Type (Etype (E))
3993 if Present (Body_E) then
3997 if not Is_Trivial_Subprogram (Scope (E)) then
3998 Error_Msg_NE -- CODEFIX
3999 ("?u?formal parameter & is not referenced!",
4005 when E_Out_Parameter =>
4008 when E_Discriminant =>
4009 Error_Msg_N ("?u?discriminant & is not referenced!", E);
4011 when E_Named_Integer |
4013 Error_Msg_N -- CODEFIX
4014 ("?u?named number & is not referenced!", E);
4016 when Formal_Object_Kind =>
4017 Error_Msg_N -- CODEFIX
4018 ("?u?formal object & is not referenced!", E);
4020 when E_Enumeration_Literal =>
4021 Error_Msg_N -- CODEFIX
4022 ("?u?literal & is not referenced!", E);
4025 Error_Msg_N -- CODEFIX
4026 ("?u?function & is not referenced!", E);
4029 Error_Msg_N -- CODEFIX
4030 ("?u?procedure & is not referenced!", E);
4033 Error_Msg_N -- CODEFIX
4034 ("?u?package & is not referenced!", E);
4037 Error_Msg_N -- CODEFIX
4038 ("?u?exception & is not referenced!", E);
4041 Error_Msg_N -- CODEFIX
4042 ("?u?label & is not referenced!", E);
4044 when E_Generic_Procedure =>
4045 Error_Msg_N -- CODEFIX
4046 ("?u?generic procedure & is never instantiated!", E);
4048 when E_Generic_Function =>
4049 Error_Msg_N -- CODEFIX
4050 ("?u?generic function & is never instantiated!", E);
4053 Error_Msg_N -- CODEFIX
4054 ("?u?type & is not referenced!", E);
4057 Error_Msg_N -- CODEFIX
4058 ("?u?& is not referenced!", E);
4061 -- Kill warnings on the entity on which the message has been posted
4063 Set_Warnings_Off (E);
4065 end Warn_On_Unreferenced_Entity;
4067 --------------------------------
4068 -- Warn_On_Useless_Assignment --
4069 --------------------------------
4071 procedure Warn_On_Useless_Assignment
4073 N : Node_Id := Empty)
4078 function Check_Ref (N : Node_Id) return Traverse_Result;
4079 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4080 -- the entity in question is found.
4082 function Test_No_Refs is new Traverse_Func (Check_Ref);
4088 function Check_Ref (N : Node_Id) return Traverse_Result is
4090 -- Check reference to our identifier. We use name equality here
4091 -- because the exception handlers have not yet been analyzed. This
4092 -- is not quite right, but it really does not matter that we fail
4093 -- to output the warning in some obscure cases of name clashes.
4095 if Nkind (N) = N_Identifier and then Chars (N) = Chars (Ent) then
4102 -- Start of processing for Warn_On_Useless_Assignment
4105 -- Check if this is a case we want to warn on, a scalar or access
4106 -- variable with the last assignment field set, with warnings enabled,
4107 -- and which is not imported or exported. We also check that it is OK
4108 -- to capture the value. We are not going to capture any value, but
4109 -- the warning message depends on the same kind of conditions.
4111 if Is_Assignable (Ent)
4112 and then not Is_Return_Object (Ent)
4113 and then Present (Last_Assignment (Ent))
4114 and then not Is_Imported (Ent)
4115 and then not Is_Exported (Ent)
4116 and then Safe_To_Capture_Value (N, Ent)
4117 and then not Has_Pragma_Unreferenced_Check_Spec (Ent)
4118 and then not Is_Junk_Name (Chars (Ent))
4120 -- Before we issue the message, check covering exception handlers.
4121 -- Search up tree for enclosing statement sequences and handlers.
4123 P := Parent (Last_Assignment (Ent));
4124 while Present (P) loop
4126 -- Something is really wrong if we don't find a handled statement
4127 -- sequence, so just suppress the warning.
4130 Set_Last_Assignment (Ent, Empty);
4133 -- When we hit a package/subprogram body, issue warning and exit
4135 elsif Nkind (P) = N_Subprogram_Body
4136 or else Nkind (P) = N_Package_Body
4138 -- Case of assigned value never referenced
4142 LA : constant Node_Id := Last_Assignment (Ent);
4145 -- Don't give this for OUT and IN OUT formals, since
4146 -- clearly caller may reference the assigned value. Also
4147 -- never give such warnings for internal variables.
4149 if Ekind (Ent) = E_Variable
4150 and then not Is_Internal_Name (Chars (Ent))
4152 -- Give appropriate message, distinguishing between
4153 -- assignment statements and out parameters.
4155 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4156 N_Parameter_Association)
4159 ("?m?& modified by call, but value never "
4160 & "referenced", LA, Ent);
4163 Error_Msg_NE -- CODEFIX
4164 ("?m?useless assignment to&, value never "
4165 & "referenced!", LA, Ent);
4170 -- Case of assigned value overwritten
4174 LA : constant Node_Id := Last_Assignment (Ent);
4177 Error_Msg_Sloc := Sloc (N);
4179 -- Give appropriate message, distinguishing between
4180 -- assignment statements and out parameters.
4182 if Nkind_In (Parent (LA), N_Procedure_Call_Statement,
4183 N_Parameter_Association)
4186 ("?m?& modified by call, but value overwritten #!",
4189 Error_Msg_NE -- CODEFIX
4190 ("?m?useless assignment to&, value overwritten #!",
4196 -- Clear last assignment indication and we are done
4198 Set_Last_Assignment (Ent, Empty);
4201 -- Enclosing handled sequence of statements
4203 elsif Nkind (P) = N_Handled_Sequence_Of_Statements then
4205 -- Check exception handlers present
4207 if Present (Exception_Handlers (P)) then
4209 -- If we are not at the top level, we regard an inner
4210 -- exception handler as a decisive indicator that we should
4211 -- not generate the warning, since the variable in question
4212 -- may be accessed after an exception in the outer block.
4214 if Nkind (Parent (P)) /= N_Subprogram_Body
4215 and then Nkind (Parent (P)) /= N_Package_Body
4217 Set_Last_Assignment (Ent, Empty);
4220 -- Otherwise we are at the outer level. An exception
4221 -- handler is significant only if it references the
4222 -- variable in question, or if the entity in question
4223 -- is an OUT or IN OUT parameter, which which case
4224 -- the caller can reference it after the exception
4225 -- handler completes.
4228 if Is_Formal (Ent) then
4229 Set_Last_Assignment (Ent, Empty);
4233 X := First (Exception_Handlers (P));
4234 while Present (X) loop
4235 if Test_No_Refs (X) = Abandon then
4236 Set_Last_Assignment (Ent, Empty);
4250 end Warn_On_Useless_Assignment;
4252 ---------------------------------
4253 -- Warn_On_Useless_Assignments --
4254 ---------------------------------
4256 procedure Warn_On_Useless_Assignments (E : Entity_Id) is
4260 Process_Deferred_References;
4262 if Warn_On_Modified_Unread
4263 and then In_Extended_Main_Source_Unit (E)
4265 Ent := First_Entity (E);
4266 while Present (Ent) loop
4267 Warn_On_Useless_Assignment (Ent);
4271 end Warn_On_Useless_Assignments;
4273 -----------------------------
4274 -- Warnings_Off_Check_Spec --
4275 -----------------------------
4277 function Warnings_Off_Check_Spec (E : Entity_Id) return Boolean is
4279 if Is_Formal (E) and then Present (Spec_Entity (E)) then
4281 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4282 -- to mess with flags on both entities.
4284 return Has_Warnings_Off (E)
4286 Has_Warnings_Off (Spec_Entity (E));
4289 return Has_Warnings_Off (E);
4291 end Warnings_Off_Check_Spec;