1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2013, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Debug
; use Debug
;
28 with Einfo
; use Einfo
;
29 with Errout
; use Errout
;
30 with Exp_Code
; use Exp_Code
;
31 with Fname
; use Fname
;
33 with 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 funny
256 -- kludge, 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
331 and then List_Length
(PA
) = 1
333 if Nkind
(First
(PA
)) = N_Parameter_Association
then
334 Find_Var
(Explicit_Actual_Parameter
(First
(PA
)));
336 Find_Var
(First
(PA
));
346 -- Any other kind of node is not something we warn for
353 ---------------------
354 -- Has_Indirection --
355 ---------------------
357 function Has_Indirection
(T
: Entity_Id
) return Boolean is
362 if Is_Access_Type
(T
) then
365 elsif Is_Private_Type
(T
)
366 and then Present
(Full_View
(T
))
367 and then Is_Access_Type
(Full_View
(T
))
371 elsif Is_Record_Type
(T
) then
374 elsif Is_Private_Type
(T
)
375 and then Present
(Full_View
(T
))
376 and then Is_Record_Type
(Full_View
(T
))
378 Rec
:= Full_View
(T
);
383 Comp
:= First_Component
(Rec
);
384 while Present
(Comp
) loop
385 if Is_Access_Type
(Etype
(Comp
))
386 or else Is_Descendent_Of_Address
(Etype
(Comp
))
391 Next_Component
(Comp
);
397 ---------------------------------
398 -- Is_Suspicious_Function_Name --
399 ---------------------------------
401 function Is_Suspicious_Function_Name
(E
: Entity_Id
) return Boolean is
404 function Substring_Present
(S
: String) return Boolean;
405 -- Returns True if name buffer has given string delimited by non-
406 -- alphabetic characters or by end of string. S is lower case.
408 -----------------------
409 -- Substring_Present --
410 -----------------------
412 function Substring_Present
(S
: String) return Boolean is
413 Len
: constant Natural := S
'Length;
416 for J
in 1 .. Name_Len
- (Len
- 1) loop
417 if Name_Buffer
(J
.. J
+ (Len
- 1)) = S
420 or else Name_Buffer
(J
- 1) not in 'a' .. 'z')
423 or else Name_Buffer
(J
+ Len
) not in 'a' .. 'z')
430 end Substring_Present
;
432 -- Start of processing for Is_Suspicious_Function_Name
436 while Present
(S
) and then S
/= Standard_Standard
loop
437 Get_Name_String
(Chars
(S
));
439 if Substring_Present
("io")
440 or else Substring_Present
("file")
441 or else Substring_Present
("network")
450 end Is_Suspicious_Function_Name
;
456 function Test_Ref
(N
: Node_Id
) return Traverse_Result
is
458 -- Waste of time to look at the expression we are testing
460 if N
= Expression
then
463 -- Direct reference to variable in question
465 elsif Is_Entity_Name
(N
)
466 and then Present
(Entity
(N
))
467 and then Entity
(N
) = Var
469 -- If this is an lvalue, then definitely abandon, since
470 -- this could be a direct modification of the variable.
472 if May_Be_Lvalue
(N
) then
476 -- If the condition contains a function call, we consider it may
477 -- be modified by side-effects from a procedure call. Otherwise,
478 -- we consider the condition may not be modified, although that
479 -- might happen if Variable is itself a by-reference parameter,
480 -- and the procedure called modifies the global object referred to
481 -- by Variable, but we actually prefer to issue a warning in this
482 -- odd case. Note that the case where the procedure called has
483 -- visibility over Variable is treated in another case below.
485 if Function_Call_Found
then
493 exit when P
= Loop_Statement
;
495 -- Abandon if at procedure call, or something strange is
496 -- going on (perhaps a node with no parent that should
497 -- have one but does not?) As always, for a warning we
498 -- prefer to just abandon the warning than get into the
499 -- business of complaining about the tree structure here.
502 or else Nkind
(P
) = N_Procedure_Call_Statement
510 -- Reference to variable renaming variable in question
512 elsif Is_Entity_Name
(N
)
513 and then Present
(Entity
(N
))
514 and then Ekind
(Entity
(N
)) = E_Variable
515 and then Present
(Renamed_Object
(Entity
(N
)))
516 and then Is_Entity_Name
(Renamed_Object
(Entity
(N
)))
517 and then Entity
(Renamed_Object
(Entity
(N
))) = Var
518 and then May_Be_Lvalue
(N
)
522 -- Call to subprogram
524 elsif Nkind
(N
) in N_Subprogram_Call
then
526 -- If subprogram is within the scope of the entity we are dealing
527 -- with as the loop variable, then it could modify this parameter,
528 -- so we abandon in this case. In the case of a subprogram that is
529 -- not an entity we also abandon. The check for no entity being
530 -- present is a defense against previous errors.
532 if not Is_Entity_Name
(Name
(N
))
533 or else No
(Entity
(Name
(N
)))
534 or else Scope_Within
(Entity
(Name
(N
)), Scope
(Var
))
539 -- If any of the arguments are of type access to subprogram, then
540 -- we may have funny side effects, so no warning in this case.
545 Actual
:= First_Actual
(N
);
546 while Present
(Actual
) loop
547 if Is_Access_Subprogram_Type
(Etype
(Actual
)) then
550 Next_Actual
(Actual
);
555 -- Declaration of the variable in question
557 elsif Nkind
(N
) = N_Object_Declaration
558 and then Defining_Identifier
(N
) = Var
563 -- All OK, continue scan
568 -- Start of processing for Check_Infinite_Loop_Warning
571 -- Skip processing if debug flag gnatd.w is set
573 if Debug_Flag_Dot_W
then
577 -- Deal with Iteration scheme present
580 Iter
: constant Node_Id
:= Iteration_Scheme
(Loop_Statement
);
583 if Present
(Iter
) then
587 if Present
(Condition
(Iter
)) then
589 -- Skip processing for while iteration with conditions actions,
590 -- since they make it too complicated to get the warning right.
592 if Present
(Condition_Actions
(Iter
)) then
596 -- Capture WHILE condition
598 Expression
:= Condition
(Iter
);
600 -- For iteration, do not process, since loop will always terminate
602 elsif Present
(Loop_Parameter_Specification
(Iter
)) then
608 -- Check chain of EXIT statements, we only process loops that have a
609 -- single exit condition (either a single EXIT WHEN statement, or a
610 -- WHILE loop not containing any EXIT WHEN statements).
613 Ident
: constant Node_Id
:= Identifier
(Loop_Statement
);
617 -- If we don't have a proper chain set, ignore call entirely. This
618 -- happens because of previous errors.
620 if No
(Entity
(Ident
))
621 or else Ekind
(Entity
(Ident
)) /= E_Loop
623 Check_Error_Detected
;
627 -- Otherwise prepare to scan list of EXIT statements
629 Exit_Stmt
:= First_Exit_Statement
(Entity
(Ident
));
630 while Present
(Exit_Stmt
) loop
632 -- Check for EXIT WHEN
634 if Present
(Condition
(Exit_Stmt
)) then
636 -- Quit processing if EXIT WHEN in WHILE loop, or more than
637 -- one EXIT WHEN statement present in the loop.
639 if Present
(Expression
) then
642 -- Otherwise capture condition from EXIT WHEN statement
645 Expression
:= Condition
(Exit_Stmt
);
648 -- If an unconditional exit statement is the last statement in the
649 -- loop, assume that no warning is needed, without any attempt at
650 -- checking whether the exit is reachable.
652 elsif Exit_Stmt
= Last
(Statements
(Loop_Statement
)) then
656 Exit_Stmt
:= Next_Exit_Statement
(Exit_Stmt
);
660 -- Return if no condition to test
662 if No
(Expression
) then
666 -- Initial conditions met, see if condition is of right form
668 Find_Var
(Expression
);
670 -- Nothing to do if local variable from source not found. If it's a
671 -- renaming, it is probably renaming something too complicated to deal
675 or else Ekind
(Var
) /= E_Variable
676 or else Is_Library_Level_Entity
(Var
)
677 or else not Comes_From_Source
(Var
)
678 or else Nkind
(Parent
(Var
)) = N_Object_Renaming_Declaration
682 -- Nothing to do if there is some indirection involved (assume that the
683 -- designated variable might be modified in some way we don't see).
684 -- However, if no function call was found, then we don't care about
685 -- indirections, because the condition must be something like "while X
686 -- /= null loop", so we don't care if X.all is modified in the loop.
688 elsif Function_Call_Found
and then Has_Indirection
(Etype
(Var
)) then
691 -- Same sort of thing for volatile variable, might be modified by
692 -- some other task or by the operating system in some way.
694 elsif Is_Volatile
(Var
) then
698 -- Filter out case of original statement sequence starting with delay.
699 -- We assume this is a multi-tasking program and that the condition
700 -- is affected by other threads (some kind of busy wait).
703 Fstm
: constant Node_Id
:=
704 Original_Node
(First
(Statements
(Loop_Statement
)));
706 if Nkind
(Fstm
) = N_Delay_Relative_Statement
707 or else Nkind
(Fstm
) = N_Delay_Until_Statement
713 -- We have a variable reference of the right form, now we scan the loop
714 -- body to see if it looks like it might not be modified
716 if No_Ref_Found
(Loop_Statement
) = OK
then
718 ("??variable& is not modified in loop body!", Ref
, Var
);
720 ("\??possible infinite loop!", Ref
);
722 end Check_Infinite_Loop_Warning
;
724 ----------------------------
725 -- Check_Low_Bound_Tested --
726 ----------------------------
728 procedure Check_Low_Bound_Tested
(Expr
: Node_Id
) is
730 if Comes_From_Source
(Expr
) then
732 L
: constant Node_Id
:= Left_Opnd
(Expr
);
733 R
: constant Node_Id
:= Right_Opnd
(Expr
);
735 if Nkind
(L
) = N_Attribute_Reference
736 and then Attribute_Name
(L
) = Name_First
737 and then Is_Entity_Name
(Prefix
(L
))
738 and then Is_Formal
(Entity
(Prefix
(L
)))
740 Set_Low_Bound_Tested
(Entity
(Prefix
(L
)));
743 if Nkind
(R
) = N_Attribute_Reference
744 and then Attribute_Name
(R
) = Name_First
745 and then Is_Entity_Name
(Prefix
(R
))
746 and then Is_Formal
(Entity
(Prefix
(R
)))
748 Set_Low_Bound_Tested
(Entity
(Prefix
(R
)));
752 end Check_Low_Bound_Tested
;
754 ----------------------
755 -- Check_References --
756 ----------------------
758 procedure Check_References
(E
: Entity_Id
; Anod
: Node_Id
:= Empty
) is
765 Accept_Statement
: Node_Id
) return Entity_Id
;
766 -- For an entry formal entity from an entry declaration, find the
767 -- corresponding body formal from the given accept statement.
769 function Missing_Subunits
return Boolean;
770 -- We suppress warnings when there are missing subunits, because this
771 -- may generate too many false positives: entities in a parent may only
772 -- be referenced in one of the subunits. We make an exception for
773 -- subunits that contain no other stubs.
775 procedure Output_Reference_Error
(M
: String);
776 -- Used to output an error message. Deals with posting the error on the
777 -- body formal in the accept case.
779 function Publicly_Referenceable
(Ent
: Entity_Id
) return Boolean;
780 -- This is true if the entity in question is potentially referenceable
781 -- from another unit. This is true for entities in packages that are at
782 -- the library level.
784 function Warnings_Off_E1
return Boolean;
785 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
786 -- or for the base type of E1T.
794 Accept_Statement
: Node_Id
) return Entity_Id
796 Body_Param
: Node_Id
;
800 -- Loop to find matching parameter in accept statement
802 Body_Param
:= First
(Parameter_Specifications
(Accept_Statement
));
803 while Present
(Body_Param
) loop
804 Body_E
:= Defining_Identifier
(Body_Param
);
806 if Chars
(Body_E
) = Chars
(E
) then
813 -- Should never fall through, should always find a match
818 ----------------------
819 -- Missing_Subunits --
820 ----------------------
822 function Missing_Subunits
return Boolean is
826 if not Unloaded_Subunits
then
828 -- Normal compilation, all subunits are present
832 elsif E
/= Main_Unit_Entity
then
834 -- No warnings on a stub that is not the main unit
838 elsif Nkind
(Unit_Declaration_Node
(E
)) in N_Proper_Body
then
839 D
:= First
(Declarations
(Unit_Declaration_Node
(E
)));
840 while Present
(D
) loop
842 -- No warnings if the proper body contains nested stubs
844 if Nkind
(D
) in N_Body_Stub
then
854 -- Missing stubs elsewhere
858 end Missing_Subunits
;
860 ----------------------------
861 -- Output_Reference_Error --
862 ----------------------------
864 procedure Output_Reference_Error
(M
: String) is
866 -- Never issue messages for internal names, nor for renamings
868 if Is_Internal_Name
(Chars
(E1
))
869 or else Nkind
(Parent
(E1
)) = N_Object_Renaming_Declaration
874 -- Don't output message for IN OUT formal unless we have the warning
875 -- flag specifically set. It is a bit odd to distinguish IN OUT
876 -- formals from other cases. This distinction is historical in
877 -- nature. Warnings for IN OUT formals were added fairly late.
879 if Ekind
(E1
) = E_In_Out_Parameter
880 and then not Check_Unreferenced_Formals
885 -- Other than accept case, post error on defining identifier
890 -- Accept case, find body formal to post the message
893 Error_Msg_NE
(M
, Body_Formal
(E1
, Accept_Statement
=> Anod
), E1
);
896 end Output_Reference_Error
;
898 ----------------------------
899 -- Publicly_Referenceable --
900 ----------------------------
902 function Publicly_Referenceable
(Ent
: Entity_Id
) return Boolean is
907 -- A formal parameter is never referenceable outside the body of its
908 -- subprogram or entry.
910 if Is_Formal
(Ent
) then
914 -- Examine parents to look for a library level package spec. But if
915 -- we find a body or block or other similar construct along the way,
916 -- we cannot be referenced.
923 -- If we get to top of tree, then publicly referenceable
928 -- If we reach a generic package declaration, then always
929 -- consider this referenceable, since any instantiation will
930 -- have access to the entities in the generic package. Note
931 -- that the package itself may not be instantiated, but then
932 -- we will get a warning for the package entity.
934 -- Note that generic formal parameters are themselves not
935 -- publicly referenceable in an instance, and warnings on them
938 when N_Generic_Package_Declaration
=>
940 not Is_List_Member
(Prev
)
941 or else List_Containing
(Prev
)
942 /= Generic_Formal_Declarations
(P
);
944 -- Similarly, the generic formals of a generic subprogram are
947 when N_Generic_Subprogram_Declaration
=>
948 if Is_List_Member
(Prev
)
949 and then List_Containing
(Prev
) =
950 Generic_Formal_Declarations
(P
)
957 -- If we reach a subprogram body, entity is not referenceable
958 -- unless it is the defining entity of the body. This will
959 -- happen, e.g. when a function is an attribute renaming that
960 -- is rewritten as a body.
962 when N_Subprogram_Body
=>
963 if Ent
/= Defining_Entity
(P
) then
969 -- If we reach any other body, definitely not referenceable
971 when N_Package_Body |
979 -- For all other cases, keep looking up tree
986 end Publicly_Referenceable
;
988 ---------------------
989 -- Warnings_Off_E1 --
990 ---------------------
992 function Warnings_Off_E1
return Boolean is
994 return Has_Warnings_Off
(E1T
)
995 or else Has_Warnings_Off
(Base_Type
(E1T
))
996 or else Warnings_Off_Check_Spec
(E1
);
999 -- Start of processing for Check_References
1002 Process_Deferred_References
;
1004 -- No messages if warnings are suppressed, or if we have detected any
1005 -- real errors so far (this last check avoids junk messages resulting
1006 -- from errors, e.g. a subunit that is not loaded).
1008 if Warning_Mode
= Suppress
1009 or else Serious_Errors_Detected
/= 0
1014 -- We also skip the messages if any subunits were not loaded (see
1015 -- comment in Sem_Ch10 to understand how this is set, and why it is
1016 -- necessary to suppress the warnings in this case).
1018 if Missing_Subunits
then
1022 -- Otherwise loop through entities, looking for suspicious stuff
1024 E1
:= First_Entity
(E
);
1025 while Present
(E1
) loop
1028 -- We are only interested in source entities. We also don't issue
1029 -- warnings within instances, since the proper place for such
1030 -- warnings is on the template when it is compiled.
1032 if Comes_From_Source
(E1
)
1033 and then Instantiation_Location
(Sloc
(E1
)) = No_Location
1035 -- We are interested in variables and out/in-out parameters, but
1036 -- we exclude protected types, too complicated to worry about.
1038 if Ekind
(E1
) = E_Variable
1040 (Ekind_In
(E1
, E_Out_Parameter
, E_In_Out_Parameter
)
1041 and then not Is_Protected_Type
(Current_Scope
))
1043 -- Case of an unassigned variable
1045 -- First gather any Unset_Reference indication for E1. In the
1046 -- case of a parameter, it is the Spec_Entity that is relevant.
1048 if Ekind
(E1
) = E_Out_Parameter
1049 and then Present
(Spec_Entity
(E1
))
1051 UR
:= Unset_Reference
(Spec_Entity
(E1
));
1053 UR
:= Unset_Reference
(E1
);
1056 -- Special processing for access types
1059 and then Is_Access_Type
(E1T
)
1061 -- For access types, the only time we made a UR entry was
1062 -- for a dereference, and so we post the appropriate warning
1063 -- here (note that the dereference may not be explicit in
1064 -- the source, for example in the case of a dispatching call
1065 -- with an anonymous access controlling formal, or of an
1066 -- assignment of a pointer involving discriminant check on
1067 -- the designated object).
1069 if not Warnings_Off_E1
then
1070 Error_Msg_NE
("??& may be null!", UR
, E1
);
1075 -- Case of variable that could be a constant. Note that we
1076 -- never signal such messages for generic package entities,
1077 -- since a given instance could have modifications outside
1080 elsif Warn_On_Constant
1081 and then (Ekind
(E1
) = E_Variable
1082 and then Has_Initial_Value
(E1
))
1083 and then Never_Set_In_Source_Check_Spec
(E1
)
1084 and then not Address_Taken
(E1
)
1085 and then not Generic_Package_Spec_Entity
(E1
)
1087 -- A special case, if this variable is volatile and not
1088 -- imported, it is not helpful to tell the programmer
1089 -- to mark the variable as constant, since this would be
1090 -- illegal by virtue of RM C.6(13).
1092 if (Is_Volatile
(E1
) or else Has_Volatile_Components
(E1
))
1093 and then not Is_Imported
(E1
)
1096 ("?k?& is not modified, volatile has no effect!", E1
);
1098 -- Another special case, Exception_Occurrence, this catches
1099 -- the case of exception choice (and a bit more too, but not
1100 -- worth doing more investigation here).
1102 elsif Is_RTE
(E1T
, RE_Exception_Occurrence
) then
1105 -- Here we give the warning if referenced and no pragma
1106 -- Unreferenced or Unmodified is present.
1111 if Ekind
(E1
) = E_Variable
then
1112 if Referenced_Check_Spec
(E1
)
1113 and then not Has_Pragma_Unreferenced_Check_Spec
(E1
)
1114 and then not Has_Pragma_Unmodified_Check_Spec
(E1
)
1116 if not Warnings_Off_E1
then
1117 Error_Msg_N
-- CODEFIX
1118 ("?k?& is not modified, "
1119 & "could be declared constant!",
1126 -- Other cases of a variable or parameter never set in source
1128 elsif Never_Set_In_Source_Check_Spec
(E1
)
1130 -- No warning if warning for this case turned off
1132 and then Warn_On_No_Value_Assigned
1134 -- No warning if address taken somewhere
1136 and then not Address_Taken
(E1
)
1138 -- No warning if explicit initial value
1140 and then not Has_Initial_Value
(E1
)
1142 -- No warning for generic package spec entities, since we
1143 -- might set them in a child unit or something like that
1145 and then not Generic_Package_Spec_Entity
(E1
)
1147 -- No warning if fully initialized type, except that for
1148 -- this purpose we do not consider access types to qualify
1149 -- as fully initialized types (relying on an access type
1150 -- variable being null when it is never set is a bit odd).
1152 -- Also we generate warning for an out parameter that is
1153 -- never referenced, since again it seems odd to rely on
1154 -- default initialization to set an out parameter value.
1156 and then (Is_Access_Type
(E1T
)
1157 or else Ekind
(E1
) = E_Out_Parameter
1158 or else not Is_Fully_Initialized_Type
(E1T
))
1160 -- Do not output complaint about never being assigned a
1161 -- value if a pragma Unmodified applies to the variable
1162 -- we are examining, or if it is a parameter, if there is
1163 -- a pragma Unreferenced for the corresponding spec, or
1164 -- if the type is marked as having unreferenced objects.
1165 -- The last is a little peculiar, but better too few than
1166 -- too many warnings in this situation.
1168 if Has_Pragma_Unreferenced_Objects
(E1T
)
1169 or else Has_Pragma_Unmodified_Check_Spec
(E1
)
1173 -- IN OUT parameter case where parameter is referenced. We
1174 -- separate this out, since this is the case where we delay
1175 -- output of the warning until more information is available
1176 -- (about use in an instantiation or address being taken).
1178 elsif Ekind
(E1
) = E_In_Out_Parameter
1179 and then Referenced_Check_Spec
(E1
)
1181 -- Suppress warning if private type, and the procedure
1182 -- has a separate declaration in a different unit. This
1183 -- is the case where the client of a package sees only
1184 -- the private type, and it may be quite reasonable
1185 -- for the logical view to be IN OUT, even if the
1186 -- implementation ends up using access types or some
1187 -- other method to achieve the local effect of a
1188 -- modification. On the other hand if the spec and body
1189 -- are in the same unit, we are in the package body and
1190 -- there we have less excuse for a junk IN OUT parameter.
1192 if Has_Private_Declaration
(E1T
)
1193 and then Present
(Spec_Entity
(E1
))
1194 and then not In_Same_Source_Unit
(E1
, Spec_Entity
(E1
))
1198 -- Suppress warning for any parameter of a dispatching
1199 -- operation, since it is quite reasonable to have an
1200 -- operation that is overridden, and for some subclasses
1201 -- needs the formal to be IN OUT and for others happens
1202 -- not to assign it.
1204 elsif Is_Dispatching_Operation
1205 (Scope
(Goto_Spec_Entity
(E1
)))
1209 -- Suppress warning if composite type contains any access
1210 -- component, since the logical effect of modifying a
1211 -- parameter may be achieved by modifying a referenced
1214 elsif Is_Composite_Type
(E1T
)
1215 and then Has_Access_Values
(E1T
)
1219 -- Suppress warning on formals of an entry body. All
1220 -- references are attached to the formal in the entry
1221 -- declaration, which are marked Is_Entry_Formal.
1223 elsif Ekind
(Scope
(E1
)) = E_Entry
1224 and then not Is_Entry_Formal
(E1
)
1228 -- OK, looks like warning for an IN OUT parameter that
1229 -- could be IN makes sense, but we delay the output of
1230 -- the warning, pending possibly finding out later on
1231 -- that the associated subprogram is used as a generic
1232 -- actual, or its address/access is taken. In these two
1233 -- cases, we suppress the warning because the context may
1234 -- force use of IN OUT, even if in this particular case
1235 -- the formal is not modified.
1238 In_Out_Warnings
.Append
(E1
);
1241 -- Other cases of formals
1243 elsif Is_Formal
(E1
) then
1244 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1245 if Referenced_Check_Spec
(E1
) then
1246 if not Has_Pragma_Unmodified_Check_Spec
(E1
)
1247 and then not Warnings_Off_E1
1249 Output_Reference_Error
1250 ("?f?formal parameter& is read but "
1251 & "never assigned!");
1254 elsif not Has_Pragma_Unreferenced_Check_Spec
(E1
)
1255 and then not Warnings_Off_E1
1257 Output_Reference_Error
1258 ("?f?formal parameter& is not referenced!");
1265 if Referenced
(E1
) then
1266 if not Has_Unmodified
(E1
)
1267 and then not Warnings_Off_E1
1268 and then not Is_Junk_Name
(Chars
(E1
))
1270 Output_Reference_Error
1271 ("?v?variable& is read but never assigned!");
1274 elsif not Has_Unreferenced
(E1
)
1275 and then not Warnings_Off_E1
1276 and then not Is_Junk_Name
(Chars
(E1
))
1278 Output_Reference_Error
-- CODEFIX
1279 ("?v?variable& is never read and never assigned!");
1282 -- Deal with special case where this variable is hidden
1283 -- by a loop variable.
1285 if Ekind
(E1
) = E_Variable
1286 and then Present
(Hiding_Loop_Variable
(E1
))
1287 and then not Warnings_Off_E1
1290 ("?v?for loop implicitly declares loop variable!",
1291 Hiding_Loop_Variable
(E1
));
1293 Error_Msg_Sloc
:= Sloc
(E1
);
1295 ("\?v?declaration hides & declared#!",
1296 Hiding_Loop_Variable
(E1
));
1303 -- Check for unset reference
1305 if Warn_On_No_Value_Assigned
and then Present
(UR
) then
1307 -- For other than access type, go back to original node to
1308 -- deal with case where original unset reference has been
1309 -- rewritten during expansion.
1311 -- In some cases, the original node may be a type conversion
1312 -- or qualification, and in this case we want the object
1315 UR
:= Original_Node
(UR
);
1316 while Nkind
(UR
) = N_Type_Conversion
1317 or else Nkind
(UR
) = N_Qualified_Expression
1318 or else Nkind
(UR
) = N_Expression_With_Actions
1320 UR
:= Expression
(UR
);
1323 -- Don't issue warning if appearing inside Initial_Condition
1324 -- pragma or aspect, since that expression is not evaluated
1325 -- at the point where it occurs in the source.
1327 if In_Pragma_Expression
(UR
, Name_Initial_Condition
) then
1331 -- Here we issue the warning, all checks completed
1333 -- If we have a return statement, this was a case of an OUT
1334 -- parameter not being set at the time of the return. (Note:
1335 -- it can't be N_Extended_Return_Statement, because those
1336 -- are only for functions, and functions do not allow OUT
1339 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1340 if Nkind
(UR
) = N_Simple_Return_Statement
1341 and then not Has_Pragma_Unmodified_Check_Spec
(E1
)
1343 if not Warnings_Off_E1
then
1345 ("?v?OUT parameter& not set before return",
1349 -- If the unset reference is a selected component
1350 -- prefix from source, mention the component as well.
1351 -- If the selected component comes from expansion, all
1352 -- we know is that the entity is not fully initialized
1353 -- at the point of the reference. Locate a random
1354 -- uninitialized component to get a better message.
1356 elsif Nkind
(Parent
(UR
)) = N_Selected_Component
then
1357 Error_Msg_Node_2
:= Selector_Name
(Parent
(UR
));
1359 if not Comes_From_Source
(Parent
(UR
)) then
1364 Comp
:= First_Entity
(E1T
);
1365 while Present
(Comp
) loop
1366 if Ekind
(Comp
) = E_Component
1367 and then Nkind
(Parent
(Comp
)) =
1368 N_Component_Declaration
1369 and then No
(Expression
(Parent
(Comp
)))
1371 Error_Msg_Node_2
:= Comp
;
1380 -- Issue proper warning. This is a case of referencing
1381 -- a variable before it has been explicitly assigned.
1382 -- For access types, UR was only set for dereferences,
1383 -- so the issue is that the value may be null.
1385 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1386 if not Warnings_Off_E1
then
1387 if Is_Access_Type
(Etype
(Parent
(UR
))) then
1388 Error_Msg_N
("?`&.&` may be null!", UR
);
1391 ("?`&.&` may be referenced before "
1392 & "it has a value!", UR
);
1396 -- All other cases of unset reference active
1398 elsif not Warnings_Off_E1
then
1400 ("?& may be referenced before it has a value!",
1409 -- Then check for unreferenced entities. Note that we are only
1410 -- interested in entities whose Referenced flag is not set.
1412 if not Referenced_Check_Spec
(E1
)
1414 -- If Referenced_As_LHS is set, then that's still interesting
1415 -- (potential "assigned but never read" case), but not if we
1416 -- have pragma Unreferenced, which cancels this warning.
1418 and then (not Referenced_As_LHS_Check_Spec
(E1
)
1419 or else not Has_Unreferenced
(E1
))
1421 -- Check that warnings on unreferenced entities are enabled
1424 ((Check_Unreferenced
and then not Is_Formal
(E1
))
1426 -- Case of warning on unreferenced formal
1429 (Check_Unreferenced_Formals
and then Is_Formal
(E1
))
1431 -- Case of warning on unread variables modified by an
1432 -- assignment, or an OUT parameter if it is the only one.
1435 (Warn_On_Modified_Unread
1436 and then Referenced_As_LHS_Check_Spec
(E1
))
1438 -- Case of warning on any unread OUT parameter (note
1439 -- such indications are only set if the appropriate
1440 -- warning options were set, so no need to recheck here.)
1443 Referenced_As_Out_Parameter_Check_Spec
(E1
))
1445 -- All other entities, including local packages that cannot be
1446 -- referenced from elsewhere, including those declared within a
1449 and then (Is_Object
(E1
)
1453 Ekind
(E1
) = E_Label
1455 Ekind
(E1
) = E_Exception
1457 Ekind
(E1
) = E_Named_Integer
1459 Ekind
(E1
) = E_Named_Real
1461 Is_Overloadable
(E1
)
1463 -- Package case, if the main unit is a package spec
1464 -- or generic package spec, then there may be a
1465 -- corresponding body that references this package
1466 -- in some other file. Otherwise we can be sure
1467 -- that there is no other reference.
1470 (Ekind
(E1
) = E_Package
1472 not Is_Package_Or_Generic_Package
1473 (Cunit_Entity
(Current_Sem_Unit
))))
1475 -- Exclude instantiations, since there is no reason why every
1476 -- entity in an instantiation should be referenced.
1478 and then Instantiation_Location
(Sloc
(E1
)) = No_Location
1480 -- Exclude formal parameters from bodies if the corresponding
1481 -- spec entity has been referenced in the case where there is
1484 and then not (Is_Formal
(E1
)
1485 and then Ekind
(Scope
(E1
)) = E_Subprogram_Body
1486 and then Present
(Spec_Entity
(E1
))
1487 and then Referenced
(Spec_Entity
(E1
)))
1489 -- Consider private type referenced if full view is referenced.
1490 -- If there is not full view, this is a generic type on which
1491 -- warnings are also useful.
1494 not (Is_Private_Type
(E1
)
1495 and then Present
(Full_View
(E1
))
1496 and then Referenced
(Full_View
(E1
)))
1498 -- Don't worry about full view, only about private type
1500 and then not Has_Private_Declaration
(E1
)
1502 -- Eliminate dispatching operations from consideration, we
1503 -- cannot tell if these are referenced or not in any easy
1504 -- manner (note this also catches Adjust/Finalize/Initialize).
1506 and then not Is_Dispatching_Operation
(E1
)
1508 -- Check entity that can be publicly referenced (we do not give
1509 -- messages for such entities, since there could be other
1510 -- units, not involved in this compilation, that contain
1511 -- relevant references.
1513 and then not Publicly_Referenceable
(E1
)
1515 -- Class wide types are marked as source entities, but they are
1516 -- not really source entities, and are always created, so we do
1517 -- not care if they are not referenced.
1519 and then Ekind
(E1
) /= E_Class_Wide_Type
1521 -- Objects other than parameters of task types are allowed to
1522 -- be non-referenced, since they start up tasks.
1524 and then ((Ekind
(E1
) /= E_Variable
1525 and then Ekind
(E1
) /= E_Constant
1526 and then Ekind
(E1
) /= E_Component
)
1527 or else not Is_Task_Type
(E1T
))
1529 -- For subunits, only place warnings on the main unit itself,
1530 -- since parent units are not completely compiled.
1532 and then (Nkind
(Unit
(Cunit
(Main_Unit
))) /= N_Subunit
1533 or else Get_Source_Unit
(E1
) = Main_Unit
)
1535 -- No warning on a return object, because these are often
1536 -- created with a single expression and an implicit return.
1537 -- If the object is a variable there will be a warning
1538 -- indicating that it could be declared constant.
1541 (Ekind
(E1
) = E_Constant
and then Is_Return_Object
(E1
))
1543 -- Suppress warnings in internal units if not in -gnatg mode
1544 -- (these would be junk warnings for an applications program,
1545 -- since they refer to problems in internal units).
1548 or else not Is_Internal_File_Name
1549 (Unit_File_Name
(Get_Source_Unit
(E1
)))
1551 -- We do not immediately flag the error. This is because we
1552 -- have not expanded generic bodies yet, and they may have
1553 -- the missing reference. So instead we park the entity on a
1554 -- list, for later processing. However for the case of an
1555 -- accept statement we want to output messages now, since
1556 -- we know we already have all information at hand, and we
1557 -- also want to have separate warnings for each accept
1558 -- statement for the same entry.
1560 if Present
(Anod
) then
1561 pragma Assert
(Is_Formal
(E1
));
1563 -- The unreferenced entity is E1, but post the warning
1564 -- on the body entity for this accept statement.
1566 if not Warnings_Off_E1
then
1567 Warn_On_Unreferenced_Entity
1568 (E1
, Body_Formal
(E1
, Accept_Statement
=> Anod
));
1571 elsif not Warnings_Off_E1
then
1572 Unreferenced_Entities
.Append
(E1
);
1576 -- Generic units are referenced in the generic body, but if they
1577 -- are not public and never instantiated we want to force a
1578 -- warning on them. We treat them as redundant constructs to
1581 elsif Is_Generic_Subprogram
(E1
)
1582 and then not Is_Instantiated
(E1
)
1583 and then not Publicly_Referenceable
(E1
)
1584 and then Instantiation_Depth
(Sloc
(E1
)) = 0
1585 and then Warn_On_Redundant_Constructs
1587 if not Warnings_Off_E1
then
1588 Unreferenced_Entities
.Append
(E1
);
1590 -- Force warning on entity
1592 Set_Referenced
(E1
, False);
1597 -- Recurse into nested package or block. Do not recurse into a formal
1598 -- package, because the corresponding body is not analyzed.
1601 if (Is_Package_Or_Generic_Package
(E1
)
1602 and then Nkind
(Parent
(E1
)) = N_Package_Specification
1604 Nkind
(Original_Node
(Unit_Declaration_Node
(E1
)))
1605 /= N_Formal_Package_Declaration
)
1607 or else Ekind
(E1
) = E_Block
1609 Check_References
(E1
);
1614 end Check_References
;
1616 ---------------------------
1617 -- Check_Unset_Reference --
1618 ---------------------------
1620 procedure Check_Unset_Reference
(N
: Node_Id
) is
1621 Typ
: constant Entity_Id
:= Etype
(N
);
1623 function Is_OK_Fully_Initialized
return Boolean;
1624 -- This function returns true if the given node N is fully initialized
1625 -- so that the reference is safe as far as this routine is concerned.
1626 -- Safe generally means that the type of N is a fully initialized type.
1627 -- The one special case is that for access types, which are always fully
1628 -- initialized, we don't consider a dereference OK since it will surely
1629 -- be dereferencing a null value, which won't do.
1631 function Prefix_Has_Dereference
(Pref
: Node_Id
) return Boolean;
1632 -- Used to test indexed or selected component or slice to see if the
1633 -- evaluation of the prefix depends on a dereference, and if so, returns
1634 -- True, in which case we always check the prefix, even if we know that
1635 -- the referenced component is initialized. Pref is the prefix to test.
1637 -----------------------------
1638 -- Is_OK_Fully_Initialized --
1639 -----------------------------
1641 function Is_OK_Fully_Initialized
return Boolean is
1643 if Is_Access_Type
(Typ
) and then Is_Dereferenced
(N
) then
1646 return Is_Fully_Initialized_Type
(Typ
);
1648 end Is_OK_Fully_Initialized
;
1650 ----------------------------
1651 -- Prefix_Has_Dereference --
1652 ----------------------------
1654 function Prefix_Has_Dereference
(Pref
: Node_Id
) return Boolean is
1656 -- If prefix is of an access type, it certainly needs a dereference
1658 if Is_Access_Type
(Etype
(Pref
)) then
1661 -- If prefix is explicit dereference, that's a dereference for sure
1663 elsif Nkind
(Pref
) = N_Explicit_Dereference
then
1666 -- If prefix is itself a component reference or slice check prefix
1668 elsif Nkind
(Pref
) = N_Slice
1669 or else Nkind
(Pref
) = N_Indexed_Component
1670 or else Nkind
(Pref
) = N_Selected_Component
1672 return Prefix_Has_Dereference
(Prefix
(Pref
));
1674 -- All other cases do not involve a dereference
1679 end Prefix_Has_Dereference
;
1681 -- Start of processing for Check_Unset_Reference
1684 -- Nothing to do if warnings suppressed
1686 if Warning_Mode
= Suppress
then
1690 -- Nothing to do for numeric or string literal. Do this test early to
1691 -- save time in a common case (it does not matter that we do not include
1692 -- character literal here, since that will be caught later on in the
1693 -- when others branch of the case statement).
1695 if Nkind
(N
) in N_Numeric_Or_String_Literal
then
1699 -- Ignore reference unless it comes from source. Almost always if we
1700 -- have a reference from generated code, it is bogus (e.g. calls to init
1701 -- procs to set default discriminant values).
1703 if not Comes_From_Source
(N
) then
1707 -- Otherwise see what kind of node we have. If the entity already has an
1708 -- unset reference, it is not necessarily the earliest in the text,
1709 -- because resolution of the prefix of selected components is completed
1710 -- before the resolution of the selected component itself. As a result,
1711 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1712 -- in right-to-left order. If there is already an unset reference, we
1713 -- check whether N is earlier before proceeding.
1717 -- For identifier or expanded name, examine the entity involved
1719 when N_Identifier | N_Expanded_Name
=>
1721 E
: constant Entity_Id
:= Entity
(N
);
1724 if (Ekind
(E
) = E_Variable
1726 Ekind
(E
) = E_Out_Parameter
)
1727 and then Never_Set_In_Source_Check_Spec
(E
)
1728 and then not Has_Initial_Value
(E
)
1729 and then (No
(Unset_Reference
(E
))
1731 Earlier_In_Extended_Unit
1732 (Sloc
(N
), Sloc
(Unset_Reference
(E
))))
1733 and then not Has_Pragma_Unmodified_Check_Spec
(E
)
1734 and then not Warnings_Off_Check_Spec
(E
)
1736 -- We may have an unset reference. The first test is whether
1737 -- this is an access to a discriminant of a record or a
1738 -- component with default initialization. Both of these
1739 -- cases can be ignored, since the actual object that is
1740 -- referenced is definitely initialized. Note that this
1741 -- covers the case of reading discriminants of an OUT
1742 -- parameter, which is OK even in Ada 83.
1744 -- Note that we are only interested in a direct reference to
1745 -- a record component here. If the reference is through an
1746 -- access type, then the access object is being referenced,
1747 -- not the record, and still deserves an unset reference.
1749 if Nkind
(Parent
(N
)) = N_Selected_Component
1750 and not Is_Access_Type
(Typ
)
1753 ES
: constant Entity_Id
:=
1754 Entity
(Selector_Name
(Parent
(N
)));
1756 if Ekind
(ES
) = E_Discriminant
1758 (Present
(Declaration_Node
(ES
))
1760 Present
(Expression
(Declaration_Node
(ES
))))
1767 -- Exclude fully initialized types
1769 if Is_OK_Fully_Initialized
then
1773 -- Here we have a potential unset reference. But before we
1774 -- get worried about it, we have to make sure that the
1775 -- entity declaration is in the same procedure as the
1776 -- reference, since if they are in separate procedures, then
1777 -- we have no idea about sequential execution.
1779 -- The tests in the loop below catch all such cases, but do
1780 -- allow the reference to appear in a loop, block, or
1781 -- package spec that is nested within the declaring scope.
1782 -- As always, it is possible to construct cases where the
1783 -- warning is wrong, that is why it is a warning.
1785 Potential_Unset_Reference
: declare
1787 SE
: constant Entity_Id
:= Scope
(E
);
1789 function Within_Postcondition
return Boolean;
1790 -- Returns True iff N is within a Postcondition, an
1791 -- Ensures component in a Test_Case, or a Contract_Cases.
1793 --------------------------
1794 -- Within_Postcondition --
1795 --------------------------
1797 function Within_Postcondition
return Boolean is
1802 while Present
(Nod
) loop
1803 if Nkind
(Nod
) = N_Pragma
1804 and then Nam_In
(Pragma_Name
(Nod
),
1806 Name_Contract_Cases
)
1810 elsif Present
(Parent
(Nod
)) then
1813 if Nkind
(P
) = N_Pragma
1815 Pragma_Name
(P
) = Name_Test_Case
1817 Nod
= Get_Ensures_From_CTC_Pragma
(P
)
1823 Nod
:= Parent
(Nod
);
1827 end Within_Postcondition
;
1829 -- Start of processing for Potential_Unset_Reference
1832 SR
:= Current_Scope
;
1834 if SR
= Standard_Standard
1835 or else Is_Subprogram
(SR
)
1836 or else Is_Concurrent_Body
(SR
)
1837 or else Is_Concurrent_Type
(SR
)
1845 -- Case of reference has an access type. This is a
1846 -- special case since access types are always set to null
1847 -- so cannot be truly uninitialized, but we still want to
1848 -- warn about cases of obvious null dereference.
1850 if Is_Access_Type
(Typ
) then
1851 Access_Type_Case
: declare
1855 (N
: Node_Id
) return Traverse_Result
;
1856 -- Process function for instantiation of Traverse
1857 -- below. Checks if N contains reference to E other
1858 -- than a dereference.
1860 function Ref_In
(Nod
: Node_Id
) return Boolean;
1861 -- Determines whether Nod contains a reference to
1862 -- the entity E that is not a dereference.
1869 (N
: Node_Id
) return Traverse_Result
1872 if Is_Entity_Name
(N
)
1873 and then Entity
(N
) = E
1874 and then not Is_Dereferenced
(N
)
1886 function Ref_In
(Nod
: Node_Id
) return Boolean is
1887 function Traverse
is new Traverse_Func
(Process
);
1889 return Traverse
(Nod
) = Abandon
;
1892 -- Start of processing for Access_Type_Case
1895 -- Don't bother if we are inside an instance, since
1896 -- the compilation of the generic template is where
1897 -- the warning should be issued.
1903 -- Don't bother if this is not the main unit. If we
1904 -- try to give this warning for with'ed units, we
1905 -- get some false positives, since we do not record
1906 -- references in other units.
1908 if not In_Extended_Main_Source_Unit
(E
)
1910 not In_Extended_Main_Source_Unit
(N
)
1915 -- We are only interested in dereferences
1917 if not Is_Dereferenced
(N
) then
1921 -- One more check, don't bother with references
1922 -- that are inside conditional statements or WHILE
1923 -- loops if the condition references the entity in
1924 -- question. This avoids most false positives.
1931 if (Nkind
(P
) = N_If_Statement
1933 Nkind
(P
) = N_Elsif_Part
)
1934 and then Ref_In
(Condition
(P
))
1938 elsif Nkind
(P
) = N_Loop_Statement
1939 and then Present
(Iteration_Scheme
(P
))
1941 Ref_In
(Condition
(Iteration_Scheme
(P
)))
1946 end Access_Type_Case
;
1949 -- One more check, don't bother if we are within a
1950 -- postcondition, since the expression occurs in a
1951 -- place unrelated to the actual test.
1953 if not Within_Postcondition
then
1955 -- Here we definitely have a case for giving a warning
1956 -- for a reference to an unset value. But we don't
1957 -- give the warning now. Instead set Unset_Reference
1958 -- in the identifier involved. The reason for this is
1959 -- that if we find the variable is never ever assigned
1960 -- a value then that warning is more important and
1961 -- there is no point in giving the reference warning.
1963 -- If this is an identifier, set the field directly
1965 if Nkind
(N
) = N_Identifier
then
1966 Set_Unset_Reference
(E
, N
);
1968 -- Otherwise it is an expanded name, so set the field
1969 -- of the actual identifier for the reference.
1972 Set_Unset_Reference
(E
, Selector_Name
(N
));
1975 end Potential_Unset_Reference
;
1979 -- Indexed component or slice
1981 when N_Indexed_Component | N_Slice
=>
1983 -- If prefix does not involve dereferencing an access type, then
1984 -- we know we are OK if the component type is fully initialized,
1985 -- since the component will have been set as part of the default
1988 if not Prefix_Has_Dereference
(Prefix
(N
))
1989 and then Is_OK_Fully_Initialized
1993 -- Look at prefix in access type case, or if the component is not
1994 -- fully initialized.
1997 Check_Unset_Reference
(Prefix
(N
));
2002 when N_Selected_Component
=>
2004 Pref
: constant Node_Id
:= Prefix
(N
);
2005 Ent
: constant Entity_Id
:= Entity
(Selector_Name
(N
));
2008 -- If prefix involves dereferencing an access type, always
2009 -- check the prefix, since the issue then is whether this
2010 -- access value is null.
2012 if Prefix_Has_Dereference
(Pref
) then
2015 -- Always go to prefix if no selector entity is set. Can this
2016 -- happen in the normal case? Not clear, but it definitely can
2017 -- happen in error cases.
2022 -- For a record component, check some cases where we have
2023 -- reasonable cause to consider that the component is known to
2024 -- be or probably is initialized. In this case, we don't care
2025 -- if the prefix itself was explicitly initialized.
2027 -- Discriminants are always considered initialized
2029 elsif Ekind
(Ent
) = E_Discriminant
then
2032 -- An explicitly initialized component is certainly initialized
2034 elsif Nkind
(Parent
(Ent
)) = N_Component_Declaration
2035 and then Present
(Expression
(Parent
(Ent
)))
2039 -- A fully initialized component is initialized
2041 elsif Is_OK_Fully_Initialized
then
2045 -- If none of those cases apply, check the record type prefix
2047 Check_Unset_Reference
(Pref
);
2050 -- For type conversions, qualifications, or expressions with actions,
2051 -- examine the expression.
2053 when N_Type_Conversion |
2054 N_Qualified_Expression |
2055 N_Expression_With_Actions
=>
2056 Check_Unset_Reference
(Expression
(N
));
2058 -- For explicit dereference, always check prefix, which will generate
2059 -- an unset reference (since this is a case of dereferencing null).
2061 when N_Explicit_Dereference
=>
2062 Check_Unset_Reference
(Prefix
(N
));
2064 -- All other cases are not cases of an unset reference
2070 end Check_Unset_Reference
;
2072 ------------------------
2073 -- Check_Unused_Withs --
2074 ------------------------
2076 procedure Check_Unused_Withs
(Spec_Unit
: Unit_Number_Type
:= No_Unit
) is
2082 Munite
: constant Entity_Id
:= Cunit_Entity
(Main_Unit
);
2083 -- This is needed for checking the special renaming case
2085 procedure Check_One_Unit
(Unit
: Unit_Number_Type
);
2086 -- Subsidiary procedure, performs checks for specified unit
2088 --------------------
2089 -- Check_One_Unit --
2090 --------------------
2092 procedure Check_One_Unit
(Unit
: Unit_Number_Type
) is
2093 Is_Visible_Renaming
: Boolean := False;
2096 procedure Check_Inner_Package
(Pack
: Entity_Id
);
2097 -- Pack is a package local to a unit in a with_clause. Both the unit
2098 -- and Pack are referenced. If none of the entities in Pack are
2099 -- referenced, then the only occurrence of Pack is in a USE clause
2100 -- or a pragma, and a warning is worthwhile as well.
2102 function Check_System_Aux
return Boolean;
2103 -- Before giving a warning on a with_clause for System, check whether
2104 -- a system extension is present.
2106 function Find_Package_Renaming
2108 L
: Entity_Id
) return Entity_Id
;
2109 -- The only reference to a context unit may be in a renaming
2110 -- declaration. If this renaming declares a visible entity, do not
2111 -- warn that the context clause could be moved to the body, because
2112 -- the renaming may be intended to re-export the unit.
2114 function Has_Visible_Entities
(P
: Entity_Id
) return Boolean;
2115 -- This function determines if a package has any visible entities.
2116 -- True is returned if there is at least one declared visible entity,
2117 -- otherwise False is returned (e.g. case of only pragmas present).
2119 -------------------------
2120 -- Check_Inner_Package --
2121 -------------------------
2123 procedure Check_Inner_Package
(Pack
: Entity_Id
) is
2125 Un
: constant Node_Id
:= Sinfo
.Unit
(Cnode
);
2127 function Check_Use_Clause
(N
: Node_Id
) return Traverse_Result
;
2128 -- If N is a use_clause for Pack, emit warning
2130 procedure Check_Use_Clauses
is new
2131 Traverse_Proc
(Check_Use_Clause
);
2133 ----------------------
2134 -- Check_Use_Clause --
2135 ----------------------
2137 function Check_Use_Clause
(N
: Node_Id
) return Traverse_Result
is
2141 if Nkind
(N
) = N_Use_Package_Clause
then
2142 Nam
:= First
(Names
(N
));
2143 while Present
(Nam
) loop
2144 if Entity
(Nam
) = Pack
then
2146 -- Suppress message if any serious errors detected
2147 -- that turn off expansion, and thus result in false
2148 -- positives for this warning.
2150 if Serious_Errors_Detected
= 0 then
2151 Error_Msg_Qual_Level
:= 1;
2152 Error_Msg_NE
-- CODEFIX
2153 ("?u?no entities of package& are referenced!",
2155 Error_Msg_Qual_Level
:= 0;
2164 end Check_Use_Clause
;
2166 -- Start of processing for Check_Inner_Package
2169 E
:= First_Entity
(Pack
);
2170 while Present
(E
) loop
2171 if Referenced_Check_Spec
(E
) then
2178 -- No entities of the package are referenced. Check whether the
2179 -- reference to the package itself is a use clause, and if so
2180 -- place a warning on it.
2182 Check_Use_Clauses
(Un
);
2183 end Check_Inner_Package
;
2185 ----------------------
2186 -- Check_System_Aux --
2187 ----------------------
2189 function Check_System_Aux
return Boolean is
2193 if Chars
(Lunit
) = Name_System
2194 and then Scope
(Lunit
) = Standard_Standard
2195 and then Present_System_Aux
2197 Ent
:= First_Entity
(System_Aux_Id
);
2198 while Present
(Ent
) loop
2199 if Referenced_Check_Spec
(Ent
) then
2208 end Check_System_Aux
;
2210 ---------------------------
2211 -- Find_Package_Renaming --
2212 ---------------------------
2214 function Find_Package_Renaming
2216 L
: Entity_Id
) return Entity_Id
2222 Is_Visible_Renaming
:= False;
2224 E1
:= First_Entity
(P
);
2225 while Present
(E1
) loop
2226 if Ekind
(E1
) = E_Package
2227 and then Renamed_Object
(E1
) = L
2229 Is_Visible_Renaming
:= not Is_Hidden
(E1
);
2232 elsif Ekind
(E1
) = E_Package
2233 and then No
(Renamed_Object
(E1
))
2234 and then not Is_Generic_Instance
(E1
)
2236 R
:= Find_Package_Renaming
(E1
, L
);
2239 Is_Visible_Renaming
:= not Is_Hidden
(R
);
2248 end Find_Package_Renaming
;
2250 --------------------------
2251 -- Has_Visible_Entities --
2252 --------------------------
2254 function Has_Visible_Entities
(P
: Entity_Id
) return Boolean is
2258 -- If unit in context is not a package, it is a subprogram that
2259 -- is not called or a generic unit that is not instantiated
2260 -- in the current unit, and warning is appropriate.
2262 if Ekind
(P
) /= E_Package
then
2266 -- If unit comes from a limited_with clause, look for declaration
2267 -- of shadow entities.
2269 if Present
(Limited_View
(P
)) then
2270 E
:= First_Entity
(Limited_View
(P
));
2272 E
:= First_Entity
(P
);
2276 and then E
/= First_Private_Entity
(P
)
2278 if Comes_From_Source
(E
)
2279 or else Present
(Limited_View
(P
))
2288 end Has_Visible_Entities
;
2290 -- Start of processing for Check_One_Unit
2293 Cnode
:= Cunit
(Unit
);
2295 -- Only do check in units that are part of the extended main unit.
2296 -- This is actually a necessary restriction, because in the case of
2297 -- subprogram acting as its own specification, there can be with's in
2298 -- subunits that we will not see.
2300 if not In_Extended_Main_Source_Unit
(Cnode
) then
2303 -- In configurable run time mode, we remove the bodies of non-inlined
2304 -- subprograms, which may lead to spurious warnings, which are
2305 -- clearly undesirable.
2307 elsif Configurable_Run_Time_Mode
2308 and then Is_Predefined_File_Name
(Unit_File_Name
(Unit
))
2313 -- Loop through context items in this unit
2315 Item
:= First
(Context_Items
(Cnode
));
2316 while Present
(Item
) loop
2317 if Nkind
(Item
) = N_With_Clause
2318 and then not Implicit_With
(Item
)
2319 and then In_Extended_Main_Source_Unit
(Item
)
2321 Lunit
:= Entity
(Name
(Item
));
2323 -- Check if this unit is referenced (skip the check if this
2324 -- is explicitly marked by a pragma Unreferenced).
2326 if not Referenced
(Lunit
)
2327 and then not Has_Unreferenced
(Lunit
)
2329 -- Suppress warnings in internal units if not in -gnatg mode
2330 -- (these would be junk warnings for an application program,
2331 -- since they refer to problems in internal units).
2334 or else not Is_Internal_File_Name
(Unit_File_Name
(Unit
))
2336 -- Here we definitely have a non-referenced unit. If it
2337 -- is the special call for a spec unit, then just set the
2338 -- flag to be read later.
2340 if Unit
= Spec_Unit
then
2341 Set_Unreferenced_In_Spec
(Item
);
2343 -- Otherwise simple unreferenced message, but skip this
2344 -- if no visible entities, because that is most likely a
2345 -- case where warning would be false positive (e.g. a
2346 -- package with only a linker options pragma and nothing
2347 -- else or a pragma elaborate with a body library task).
2349 elsif Has_Visible_Entities
(Entity
(Name
(Item
))) then
2350 Error_Msg_N
-- CODEFIX
2351 ("?u?unit& is not referenced!", Name
(Item
));
2355 -- If main unit is a renaming of this unit, then we consider
2356 -- the with to be OK (obviously it is needed in this case).
2357 -- This may be transitive: the unit in the with_clause may
2358 -- itself be a renaming, in which case both it and the main
2359 -- unit rename the same ultimate package.
2361 elsif Present
(Renamed_Entity
(Munite
))
2363 (Renamed_Entity
(Munite
) = Lunit
2364 or else Renamed_Entity
(Munite
) = Renamed_Entity
(Lunit
))
2368 -- If this unit is referenced, and it is a package, we do
2369 -- another test, to see if any of the entities in the package
2370 -- are referenced. If none of the entities are referenced, we
2371 -- still post a warning. This occurs if the only use of the
2372 -- package is in a use clause, or in a package renaming
2373 -- declaration. This check is skipped for packages that are
2374 -- renamed in a spec, since the entities in such a package are
2375 -- visible to clients via the renaming.
2377 elsif Ekind
(Lunit
) = E_Package
2378 and then not Renamed_In_Spec
(Lunit
)
2380 -- If Is_Instantiated is set, it means that the package is
2381 -- implicitly instantiated (this is the case of parent
2382 -- instance or an actual for a generic package formal), and
2383 -- this counts as a reference.
2385 if Is_Instantiated
(Lunit
) then
2388 -- If no entities in package, and there is a pragma
2389 -- Elaborate_Body present, then assume that this with is
2390 -- done for purposes of this elaboration.
2392 elsif No
(First_Entity
(Lunit
))
2393 and then Has_Pragma_Elaborate_Body
(Lunit
)
2397 -- Otherwise see if any entities have been referenced
2400 if Limited_Present
(Item
) then
2401 Ent
:= First_Entity
(Limited_View
(Lunit
));
2403 Ent
:= First_Entity
(Lunit
);
2407 -- No more entities, and we did not find one that was
2408 -- referenced. Means we have a definite case of a with
2409 -- none of whose entities was referenced.
2413 -- If in spec, just set the flag
2415 if Unit
= Spec_Unit
then
2416 Set_No_Entities_Ref_In_Spec
(Item
);
2418 elsif Check_System_Aux
then
2421 -- Else give the warning
2424 -- Warn if we unreferenced flag set and we have
2425 -- not had serious errors. The reason we inhibit
2426 -- the message if there are errors is to prevent
2427 -- false positives from disabling expansion.
2429 if not Has_Unreferenced
(Entity
(Name
(Item
)))
2430 and then Serious_Errors_Detected
= 0
2432 Error_Msg_N
-- CODEFIX
2433 ("?u?no entities of & are referenced!",
2437 -- Look for renamings of this package, and flag
2438 -- them as well. If the original package has
2439 -- warnings off, we suppress the warning on the
2440 -- renaming as well.
2442 Pack
:= Find_Package_Renaming
(Munite
, Lunit
);
2445 and then not Has_Warnings_Off
(Lunit
)
2446 and then not Has_Unreferenced
(Pack
)
2448 Error_Msg_NE
-- CODEFIX
2449 ("?u?no entities of & are referenced!",
2450 Unit_Declaration_Node
(Pack
),
2457 -- Case of entity being referenced. The reference may
2458 -- come from a limited_with_clause, in which case the
2459 -- limited view of the entity carries the flag.
2461 elsif Referenced_Check_Spec
(Ent
)
2462 or else Referenced_As_LHS_Check_Spec
(Ent
)
2463 or else Referenced_As_Out_Parameter_Check_Spec
(Ent
)
2465 (From_Limited_With
(Ent
)
2466 and then Is_Incomplete_Type
(Ent
)
2467 and then Present
(Non_Limited_View
(Ent
))
2468 and then Referenced
(Non_Limited_View
(Ent
)))
2470 -- This means that the with is indeed fine, in that
2471 -- it is definitely needed somewhere, and we can
2472 -- quit worrying about this one...
2474 -- Except for one little detail: if either of the
2475 -- flags was set during spec processing, this is
2476 -- where we complain that the with could be moved
2477 -- from the spec. If the spec contains a visible
2478 -- renaming of the package, inhibit warning to move
2479 -- with_clause to body.
2481 if Ekind
(Munite
) = E_Package_Body
then
2483 Find_Package_Renaming
2484 (Spec_Entity
(Munite
), Lunit
);
2489 -- If a renaming is present in the spec do not warn
2490 -- because the body or child unit may depend on it.
2493 and then Renamed_Entity
(Pack
) = Lunit
2497 elsif Unreferenced_In_Spec
(Item
) then
2498 Error_Msg_N
-- CODEFIX
2499 ("?u?unit& is not referenced in spec!",
2502 elsif No_Entities_Ref_In_Spec
(Item
) then
2503 Error_Msg_N
-- CODEFIX
2504 ("?u?no entities of & are referenced in spec!",
2508 if Ekind
(Ent
) = E_Package
then
2509 Check_Inner_Package
(Ent
);
2515 if not Is_Visible_Renaming
then
2516 Error_Msg_N
-- CODEFIX
2517 ("\?u?with clause might be moved to body!",
2523 -- Move to next entity to continue search
2531 -- For a generic package, the only interesting kind of
2532 -- reference is an instantiation, since entities cannot be
2533 -- referenced directly.
2535 elsif Is_Generic_Unit
(Lunit
) then
2537 -- Unit was never instantiated, set flag for case of spec
2538 -- call, or give warning for normal call.
2540 if not Is_Instantiated
(Lunit
) then
2541 if Unit
= Spec_Unit
then
2542 Set_Unreferenced_In_Spec
(Item
);
2544 Error_Msg_N
-- CODEFIX
2545 ("?u?unit& is never instantiated!", Name
(Item
));
2548 -- If unit was indeed instantiated, make sure that flag is
2549 -- not set showing it was uninstantiated in the spec, and if
2550 -- so, give warning.
2552 elsif Unreferenced_In_Spec
(Item
) then
2554 ("?u?unit& is not instantiated in spec!", Name
(Item
));
2555 Error_Msg_N
-- CODEFIX
2556 ("\?u?with clause can be moved to body!", Name
(Item
));
2565 -- Start of processing for Check_Unused_Withs
2568 -- Immediate return if no semantics or warning flag not set
2570 if not Opt
.Check_Withs
or else Operating_Mode
= Check_Syntax
then
2574 Process_Deferred_References
;
2576 -- Flag any unused with clauses. For a subunit, check only the units
2577 -- in its context, not those of the parent, which may be needed by other
2578 -- subunits. We will get the full warnings when we compile the parent,
2579 -- but the following is helpful when compiling a subunit by itself.
2581 if Nkind
(Unit
(Cunit
(Main_Unit
))) = N_Subunit
then
2582 if Current_Sem_Unit
= Main_Unit
then
2583 Check_One_Unit
(Main_Unit
);
2589 -- Process specified units
2591 if Spec_Unit
= No_Unit
then
2593 -- For main call, check all units
2595 for Unit
in Main_Unit
.. Last_Unit
loop
2596 Check_One_Unit
(Unit
);
2600 -- For call for spec, check only the spec
2602 Check_One_Unit
(Spec_Unit
);
2604 end Check_Unused_Withs
;
2606 ---------------------------------
2607 -- Generic_Package_Spec_Entity --
2608 ---------------------------------
2610 function Generic_Package_Spec_Entity
(E
: Entity_Id
) return Boolean is
2614 if Is_Package_Body_Entity
(E
) then
2620 if S
= Standard_Standard
then
2623 elsif Ekind
(S
) = E_Generic_Package
then
2626 elsif Ekind
(S
) = E_Package
then
2634 end Generic_Package_Spec_Entity
;
2636 ----------------------
2637 -- Goto_Spec_Entity --
2638 ----------------------
2640 function Goto_Spec_Entity
(E
: Entity_Id
) return Entity_Id
is
2643 and then Present
(Spec_Entity
(E
))
2645 return Spec_Entity
(E
);
2649 end Goto_Spec_Entity
;
2651 --------------------------------------
2652 -- Has_Pragma_Unmodified_Check_Spec --
2653 --------------------------------------
2655 function Has_Pragma_Unmodified_Check_Spec
2656 (E
: Entity_Id
) return Boolean
2659 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2661 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2662 -- to mess with Unmodified flags on both body and spec entities.
2664 return Has_Unmodified
(E
)
2666 Has_Unmodified
(Spec_Entity
(E
));
2669 return Has_Unmodified
(E
);
2671 end Has_Pragma_Unmodified_Check_Spec
;
2673 ----------------------------------------
2674 -- Has_Pragma_Unreferenced_Check_Spec --
2675 ----------------------------------------
2677 function Has_Pragma_Unreferenced_Check_Spec
2678 (E
: Entity_Id
) return Boolean
2681 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2683 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2684 -- to mess with flags on both entities.
2686 return Has_Unreferenced
(E
)
2688 Has_Unreferenced
(Spec_Entity
(E
));
2691 return Has_Unreferenced
(E
);
2693 end Has_Pragma_Unreferenced_Check_Spec
;
2699 procedure Initialize
is
2701 Warnings_Off_Pragmas
.Init
;
2702 Unreferenced_Entities
.Init
;
2703 In_Out_Warnings
.Init
;
2706 ------------------------------------
2707 -- Never_Set_In_Source_Check_Spec --
2708 ------------------------------------
2710 function Never_Set_In_Source_Check_Spec
(E
: Entity_Id
) return Boolean is
2712 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2713 return Never_Set_In_Source
(E
)
2715 Never_Set_In_Source
(Spec_Entity
(E
));
2717 return Never_Set_In_Source
(E
);
2719 end Never_Set_In_Source_Check_Spec
;
2721 -------------------------------------
2722 -- Operand_Has_Warnings_Suppressed --
2723 -------------------------------------
2725 function Operand_Has_Warnings_Suppressed
(N
: Node_Id
) return Boolean is
2727 function Check_For_Warnings
(N
: Node_Id
) return Traverse_Result
;
2728 -- Function used to check one node to see if it is or was originally
2729 -- a reference to an entity for which Warnings are off. If so, Abandon
2730 -- is returned, otherwise OK_Orig is returned to continue the traversal
2731 -- of the original expression.
2733 function Traverse
is new Traverse_Func
(Check_For_Warnings
);
2734 -- Function used to traverse tree looking for warnings
2736 ------------------------
2737 -- Check_For_Warnings --
2738 ------------------------
2740 function Check_For_Warnings
(N
: Node_Id
) return Traverse_Result
is
2741 R
: constant Node_Id
:= Original_Node
(N
);
2744 if Nkind
(R
) in N_Has_Entity
2745 and then Present
(Entity
(R
))
2746 and then Has_Warnings_Off
(Entity
(R
))
2752 end Check_For_Warnings
;
2754 -- Start of processing for Operand_Has_Warnings_Suppressed
2757 return Traverse
(N
) = Abandon
;
2759 -- If any exception occurs, then something has gone wrong, and this is
2760 -- only a minor aesthetic issue anyway, so just say we did not find what
2761 -- we are looking for, rather than blow up.
2766 end Operand_Has_Warnings_Suppressed
;
2768 -----------------------------------------
2769 -- Output_Non_Modified_In_Out_Warnings --
2770 -----------------------------------------
2772 procedure Output_Non_Modified_In_Out_Warnings
is
2774 function No_Warn_On_In_Out
(E
: Entity_Id
) return Boolean;
2775 -- Given a formal parameter entity E, determines if there is a reason to
2776 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2777 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2778 -- if we have seen the address of the subprogram being taken, or if the
2779 -- subprogram is used as a generic actual (in the latter cases the
2780 -- context may force use of IN OUT, even if the parameter is not
2781 -- modifies for this particular case.
2783 -----------------------
2784 -- No_Warn_On_In_Out --
2785 -----------------------
2787 function No_Warn_On_In_Out
(E
: Entity_Id
) return Boolean is
2788 S
: constant Entity_Id
:= Scope
(E
);
2789 SE
: constant Entity_Id
:= Spec_Entity
(E
);
2792 -- Do not warn if address is taken, since funny business may be going
2793 -- on in treating the parameter indirectly as IN OUT.
2795 if Address_Taken
(S
)
2796 or else (Present
(SE
) and then Address_Taken
(Scope
(SE
)))
2800 -- Do not warn if used as a generic actual, since the generic may be
2801 -- what is forcing the use of an "unnecessary" IN OUT.
2803 elsif Used_As_Generic_Actual
(S
)
2804 or else (Present
(SE
) and then Used_As_Generic_Actual
(Scope
(SE
)))
2808 -- Else test warnings off
2810 elsif Warnings_Off_Check_Spec
(S
) then
2813 -- All tests for suppressing warning failed
2818 end No_Warn_On_In_Out
;
2820 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2823 -- Loop through entities for which a warning may be needed
2825 for J
in In_Out_Warnings
.First
.. In_Out_Warnings
.Last
loop
2827 E1
: constant Entity_Id
:= In_Out_Warnings
.Table
(J
);
2830 -- Suppress warning in specific cases (see details in comments for
2831 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2833 if Has_Pragma_Unmodified_Check_Spec
(E1
)
2834 or else No_Warn_On_In_Out
(E1
)
2838 -- Here we generate the warning
2841 -- If -gnatwc is set then output message that we could be IN
2843 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
2844 if Warn_On_Constant
then
2846 ("?u?formal parameter & is not modified!", E1
);
2848 ("\?u?mode could be IN instead of `IN OUT`!", E1
);
2850 -- We do not generate warnings for IN OUT parameters
2851 -- unless we have at least -gnatwu. This is deliberately
2852 -- inconsistent with the treatment of variables, but
2853 -- otherwise we get too many unexpected warnings in
2856 elsif Check_Unreferenced
then
2858 ("?u?formal parameter& is read but "
2859 & "never assigned!", E1
);
2863 -- Kill any other warnings on this entity, since this is the
2864 -- one that should dominate any other unreferenced warning.
2866 Set_Warnings_Off
(E1
);
2870 end Output_Non_Modified_In_Out_Warnings
;
2872 ----------------------------------------
2873 -- Output_Obsolescent_Entity_Warnings --
2874 ----------------------------------------
2876 procedure Output_Obsolescent_Entity_Warnings
(N
: Node_Id
; E
: Entity_Id
) is
2877 P
: constant Node_Id
:= Parent
(N
);
2883 -- Do not output message if we are the scope of standard. This means
2884 -- we have a reference from a context clause from when it is originally
2885 -- processed, and that's too early to tell whether it is an obsolescent
2886 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2887 -- sure that we have a later call when the scope is available. This test
2888 -- also eliminates all messages for use clauses, which is fine (we do
2889 -- not want messages for use clauses, since they are always redundant
2890 -- with respect to the associated with clause).
2892 if S
= Standard_Standard
then
2896 -- Do not output message if we are in scope of an obsolescent package
2900 if Is_Obsolescent
(S
) then
2905 exit when S
= Standard_Standard
;
2908 -- Here we will output the message
2910 Error_Msg_Sloc
:= Sloc
(E
);
2912 -- Case of with clause
2914 if Nkind
(P
) = N_With_Clause
then
2915 if Ekind
(E
) = E_Package
then
2917 ("??with of obsolescent package& declared#", N
, E
);
2918 elsif Ekind
(E
) = E_Procedure
then
2920 ("??with of obsolescent procedure& declared#", N
, E
);
2923 ("??with of obsolescent function& declared#", N
, E
);
2926 -- If we do not have a with clause, then ignore any reference to an
2927 -- obsolescent package name. We only want to give the one warning of
2928 -- withing the package, not one each time it is used to qualify.
2930 elsif Ekind
(E
) = E_Package
then
2933 -- Procedure call statement
2935 elsif Nkind
(P
) = N_Procedure_Call_Statement
then
2937 ("??call to obsolescent procedure& declared#", N
, E
);
2941 elsif Nkind
(P
) = N_Function_Call
then
2943 ("??call to obsolescent function& declared#", N
, E
);
2945 -- Reference to obsolescent type
2947 elsif Is_Type
(E
) then
2949 ("??reference to obsolescent type& declared#", N
, E
);
2951 -- Reference to obsolescent component
2953 elsif Ekind_In
(E
, E_Component
, E_Discriminant
) then
2955 ("??reference to obsolescent component& declared#", N
, E
);
2957 -- Reference to obsolescent variable
2959 elsif Ekind
(E
) = E_Variable
then
2961 ("??reference to obsolescent variable& declared#", N
, E
);
2963 -- Reference to obsolescent constant
2965 elsif Ekind
(E
) = E_Constant
or else Ekind
(E
) in Named_Kind
then
2967 ("??reference to obsolescent constant& declared#", N
, E
);
2969 -- Reference to obsolescent enumeration literal
2971 elsif Ekind
(E
) = E_Enumeration_Literal
then
2973 ("??reference to obsolescent enumeration literal& declared#", N
, E
);
2975 -- Generic message for any other case we missed
2979 ("??reference to obsolescent entity& declared#", N
, E
);
2982 -- Output additional warning if present
2984 for J
in Obsolescent_Warnings
.First
.. Obsolescent_Warnings
.Last
loop
2985 if Obsolescent_Warnings
.Table
(J
).Ent
= E
then
2986 String_To_Name_Buffer
(Obsolescent_Warnings
.Table
(J
).Msg
);
2987 Error_Msg_Strlen
:= Name_Len
;
2988 Error_Msg_String
(1 .. Name_Len
) := Name_Buffer
(1 .. Name_Len
);
2989 Error_Msg_N
("\\??~", N
);
2993 end Output_Obsolescent_Entity_Warnings
;
2995 ----------------------------------
2996 -- Output_Unreferenced_Messages --
2997 ----------------------------------
2999 procedure Output_Unreferenced_Messages
is
3001 for J
in Unreferenced_Entities
.First
..
3002 Unreferenced_Entities
.Last
3004 Warn_On_Unreferenced_Entity
(Unreferenced_Entities
.Table
(J
));
3006 end Output_Unreferenced_Messages
;
3008 -----------------------------------------
3009 -- Output_Unused_Warnings_Off_Warnings --
3010 -----------------------------------------
3012 procedure Output_Unused_Warnings_Off_Warnings
is
3014 for J
in Warnings_Off_Pragmas
.First
.. Warnings_Off_Pragmas
.Last
loop
3016 Wentry
: Warnings_Off_Entry
renames Warnings_Off_Pragmas
.Table
(J
);
3017 N
: Node_Id
renames Wentry
.N
;
3018 E
: Node_Id
renames Wentry
.E
;
3021 -- Turn off Warnings_Off, or we won't get the warning
3023 Set_Warnings_Off
(E
, False);
3025 -- Nothing to do if pragma was used to suppress a general warning
3027 if Warnings_Off_Used
(E
) then
3030 -- If pragma was used both in unmodified and unreferenced contexts
3031 -- then that's as good as the general case, no warning.
3033 elsif Warnings_Off_Used_Unmodified
(E
)
3035 Warnings_Off_Used_Unreferenced
(E
)
3039 -- Used only in context where Unmodified would have worked
3041 elsif Warnings_Off_Used_Unmodified
(E
) then
3043 ("?W?could use Unmodified instead of "
3044 & "Warnings Off for &", Pragma_Identifier
(N
), E
);
3046 -- Used only in context where Unreferenced would have worked
3048 elsif Warnings_Off_Used_Unreferenced
(E
) then
3050 ("?W?could use Unreferenced instead of "
3051 & "Warnings Off for &", Pragma_Identifier
(N
), E
);
3057 ("?W?pragma Warnings Off for & unused, "
3058 & "could be omitted", N
, E
);
3062 end Output_Unused_Warnings_Off_Warnings
;
3064 ---------------------------
3065 -- Referenced_Check_Spec --
3066 ---------------------------
3068 function Referenced_Check_Spec
(E
: Entity_Id
) return Boolean is
3070 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3071 return Referenced
(E
) or else Referenced
(Spec_Entity
(E
));
3073 return Referenced
(E
);
3075 end Referenced_Check_Spec
;
3077 ----------------------------------
3078 -- Referenced_As_LHS_Check_Spec --
3079 ----------------------------------
3081 function Referenced_As_LHS_Check_Spec
(E
: Entity_Id
) return Boolean is
3083 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3084 return Referenced_As_LHS
(E
)
3085 or else Referenced_As_LHS
(Spec_Entity
(E
));
3087 return Referenced_As_LHS
(E
);
3089 end Referenced_As_LHS_Check_Spec
;
3091 --------------------------------------------
3092 -- Referenced_As_Out_Parameter_Check_Spec --
3093 --------------------------------------------
3095 function Referenced_As_Out_Parameter_Check_Spec
3096 (E
: Entity_Id
) return Boolean
3099 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3100 return Referenced_As_Out_Parameter
(E
)
3101 or else Referenced_As_Out_Parameter
(Spec_Entity
(E
));
3103 return Referenced_As_Out_Parameter
(E
);
3105 end Referenced_As_Out_Parameter_Check_Spec
;
3107 -----------------------------
3108 -- Warn_On_Known_Condition --
3109 -----------------------------
3111 procedure Warn_On_Known_Condition
(C
: Node_Id
) is
3113 Orig
: constant Node_Id
:= Original_Node
(C
);
3114 Test_Result
: Boolean;
3116 function Is_Known_Branch
return Boolean;
3117 -- If the type of the condition is Boolean, the constant value of the
3118 -- condition is a boolean literal. If the type is a derived boolean
3119 -- type, the constant is wrapped in a type conversion of the derived
3120 -- literal. If the value of the condition is not a literal, no warnings
3121 -- can be produced. This function returns True if the result can be
3122 -- determined, and Test_Result is set True/False accordingly. Otherwise
3123 -- False is returned, and Test_Result is unchanged.
3125 procedure Track
(N
: Node_Id
; Loc
: Node_Id
);
3126 -- Adds continuation warning(s) pointing to reason (assignment or test)
3127 -- for the operand of the conditional having a known value (or at least
3128 -- enough is known about the value to issue the warning). N is the node
3129 -- which is judged to have a known value. Loc is the warning location.
3131 ---------------------
3132 -- Is_Known_Branch --
3133 ---------------------
3135 function Is_Known_Branch
return Boolean is
3137 if Etype
(C
) = Standard_Boolean
3138 and then Is_Entity_Name
(C
)
3140 (Entity
(C
) = Standard_False
or else Entity
(C
) = Standard_True
)
3142 Test_Result
:= Entity
(C
) = Standard_True
;
3145 elsif Is_Boolean_Type
(Etype
(C
))
3146 and then Nkind
(C
) = N_Unchecked_Type_Conversion
3147 and then Is_Entity_Name
(Expression
(C
))
3148 and then Ekind
(Entity
(Expression
(C
))) = E_Enumeration_Literal
3151 Chars
(Entity
(Expression
(C
))) = Chars
(Standard_True
);
3157 end Is_Known_Branch
;
3163 procedure Track
(N
: Node_Id
; Loc
: Node_Id
) is
3164 Nod
: constant Node_Id
:= Original_Node
(N
);
3167 if Nkind
(Nod
) in N_Op_Compare
then
3168 Track
(Left_Opnd
(Nod
), Loc
);
3169 Track
(Right_Opnd
(Nod
), Loc
);
3171 elsif Is_Entity_Name
(Nod
)
3172 and then Is_Object
(Entity
(Nod
))
3175 CV
: constant Node_Id
:= Current_Value
(Entity
(Nod
));
3178 if Present
(CV
) then
3179 Error_Msg_Sloc
:= Sloc
(CV
);
3181 if Nkind
(CV
) not in N_Subexpr
then
3182 Error_Msg_N
("\\?(see test #)", Loc
);
3184 elsif Nkind
(Parent
(CV
)) =
3185 N_Case_Statement_Alternative
3187 Error_Msg_N
("\\?(see case alternative #)", Loc
);
3190 Error_Msg_N
("\\?(see assignment #)", Loc
);
3197 -- Start of processing for Warn_On_Known_Condition
3200 -- Adjust SCO condition if from source
3203 and then Comes_From_Source
(Orig
)
3204 and then Is_Known_Branch
3210 Atrue
:= Test_Result
;
3212 if Present
(Parent
(C
)) and then Nkind
(Parent
(C
)) = N_Op_Not
then
3216 Set_SCO_Condition
(Orig
, Atrue
);
3220 -- Argument replacement in an inlined body can make conditions static.
3221 -- Do not emit warnings in this case.
3223 if In_Inlined_Body
then
3227 if Constant_Condition_Warnings
3228 and then Is_Known_Branch
3229 and then Comes_From_Source
(Orig
)
3230 and then not In_Instance
3232 -- Don't warn if comparison of result of attribute against a constant
3233 -- value, since this is likely legitimate conditional compilation.
3235 if Nkind
(Orig
) in N_Op_Compare
3236 and then Compile_Time_Known_Value
(Right_Opnd
(Orig
))
3237 and then Nkind
(Original_Node
(Left_Opnd
(Orig
))) =
3238 N_Attribute_Reference
3243 -- See if this is in a statement or a declaration
3247 -- If tree is not attached, do not issue warning (this is very
3248 -- peculiar, and probably arises from some other error condition)
3253 -- If we are in a declaration, then no warning, since in practice
3254 -- conditionals in declarations are used for intended tests which
3255 -- may be known at compile time, e.g. things like
3257 -- x : constant Integer := 2 + (Word'Size = 32);
3259 -- And a warning is annoying in such cases
3261 elsif Nkind
(P
) in N_Declaration
3263 Nkind
(P
) in N_Later_Decl_Item
3267 -- Don't warn in assert or check pragma, since presumably tests in
3268 -- such a context are very definitely intended, and might well be
3269 -- known at compile time. Note that we have to test the original
3270 -- node, since assert pragmas get rewritten at analysis time.
3272 elsif Nkind
(Original_Node
(P
)) = N_Pragma
3273 and then Nam_In
(Pragma_Name
(Original_Node
(P
)), Name_Assert
,
3279 exit when Is_Statement
(P
);
3283 -- Here we issue the warning unless some sub-operand has warnings
3284 -- set off, in which case we suppress the warning for the node. If
3285 -- the original expression is an inequality, it has been expanded
3286 -- into a negation, and the value of the original expression is the
3287 -- negation of the equality. If the expression is an entity that
3288 -- appears within a negation, it is clearer to flag the negation
3289 -- itself, and report on its constant value.
3291 if not Operand_Has_Warnings_Suppressed
(C
) then
3293 True_Branch
: Boolean := Test_Result
;
3294 Cond
: Node_Id
:= C
;
3297 if Present
(Parent
(C
))
3298 and then Nkind
(Parent
(C
)) = N_Op_Not
3300 True_Branch
:= not True_Branch
;
3305 if Is_Entity_Name
(Original_Node
(C
))
3306 and then Nkind
(Cond
) /= N_Op_Not
3309 ("object & is always True?c?", Cond
, Original_Node
(C
));
3310 Track
(Original_Node
(C
), Cond
);
3313 Error_Msg_N
("condition is always True?c?", Cond
);
3318 Error_Msg_N
("condition is always False?c?", Cond
);
3324 end Warn_On_Known_Condition
;
3326 ---------------------------------------
3327 -- Warn_On_Modified_As_Out_Parameter --
3328 ---------------------------------------
3330 function Warn_On_Modified_As_Out_Parameter
(E
: Entity_Id
) return Boolean is
3333 (Warn_On_Modified_Unread
and then Is_Only_Out_Parameter
(E
))
3334 or else Warn_On_All_Unread_Out_Parameters
;
3335 end Warn_On_Modified_As_Out_Parameter
;
3337 ---------------------------------
3338 -- Warn_On_Overlapping_Actuals --
3339 ---------------------------------
3341 procedure Warn_On_Overlapping_Actuals
(Subp
: Entity_Id
; N
: Node_Id
) is
3342 Act1
, Act2
: Node_Id
;
3343 Form1
, Form2
: Entity_Id
;
3345 function Is_Covered_Formal
(Formal
: Node_Id
) return Boolean;
3346 -- Return True if Formal is covered by the rule
3348 function Refer_Same_Object
(Act1
, Act2
: Node_Id
) return Boolean;
3349 -- Two names are known to refer to the same object if the two names
3350 -- are known to denote the same object; or one of the names is a
3351 -- selected_component, indexed_component, or slice and its prefix is
3352 -- known to refer to the same object as the other name; or one of the
3353 -- two names statically denotes a renaming declaration whose renamed
3354 -- object_name is known to refer to the same object as the other name
3355 -- (RM 6.4.1(6.11/3))
3357 -----------------------
3358 -- Refer_Same_Object --
3359 -----------------------
3361 function Refer_Same_Object
(Act1
, Act2
: Node_Id
) return Boolean is
3363 return Denotes_Same_Object
(Act1
, Act2
)
3364 or else Denotes_Same_Prefix
(Act1
, Act2
);
3365 end Refer_Same_Object
;
3367 -----------------------
3368 -- Is_Covered_Formal --
3369 -----------------------
3371 function Is_Covered_Formal
(Formal
: Node_Id
) return Boolean is
3374 Ekind_In
(Formal
, E_Out_Parameter
, E_In_Out_Parameter
)
3375 and then (Is_Elementary_Type
(Etype
(Formal
))
3376 or else Is_Record_Type
(Etype
(Formal
))
3377 or else Is_Array_Type
(Etype
(Formal
)));
3378 end Is_Covered_Formal
;
3381 if Ada_Version
< Ada_2012
and then not Warn_On_Overlap
then
3385 -- Exclude calls rewritten as enumeration literals
3387 if Nkind
(N
) not in N_Subprogram_Call
3388 and then Nkind
(N
) /= N_Entry_Call_Statement
3393 -- If a call C has two or more parameters of mode in out or out that are
3394 -- of an elementary type, then the call is legal only if for each name
3395 -- N that is passed as a parameter of mode in out or out to the call C,
3396 -- there is no other name among the other parameters of mode in out or
3397 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3399 -- If appropriate warning switch is set, we also report warnings on
3400 -- overlapping parameters that are record types or array types.
3402 Form1
:= First_Formal
(Subp
);
3403 Act1
:= First_Actual
(N
);
3404 while Present
(Form1
) and then Present
(Act1
) loop
3405 if Is_Covered_Formal
(Form1
) then
3406 Form2
:= First_Formal
(Subp
);
3407 Act2
:= First_Actual
(N
);
3408 while Present
(Form2
) and then Present
(Act2
) loop
3410 and then Is_Covered_Formal
(Form2
)
3411 and then Refer_Same_Object
(Act1
, Act2
)
3413 -- Guard against previous errors
3416 or else No
(Etype
(Act1
))
3417 or else No
(Etype
(Act2
))
3421 -- If the actual is a function call in prefix notation,
3422 -- there is no real overlap.
3424 elsif Nkind
(Act2
) = N_Function_Call
then
3427 -- If type is not by-copy, assume that aliasing is intended
3430 Present
(Underlying_Type
(Etype
(Form1
)))
3432 (Is_By_Reference_Type
(Underlying_Type
(Etype
(Form1
)))
3434 Convention
(Underlying_Type
(Etype
(Form1
))) =
3435 Convention_Ada_Pass_By_Reference
)
3439 -- Under Ada 2012 we only report warnings on overlapping
3440 -- arrays and record types if switch is set.
3442 elsif Ada_Version
>= Ada_2012
3443 and then not Is_Elementary_Type
(Etype
(Form1
))
3444 and then not Warn_On_Overlap
3448 -- Here we may need to issue overlap message
3453 -- Overlap checking is an error only in Ada 2012. For
3454 -- earlier versions of Ada, this is a warning.
3456 Ada_Version
< Ada_2012
3458 -- Overlap is only illegal in Ada 2012 in the case of
3459 -- elementary types (passed by copy). For other types,
3460 -- we always have a warning in all Ada versions.
3462 or else not Is_Elementary_Type
(Etype
(Form1
))
3464 -- Finally, debug flag -gnatd.E changes the error to a
3465 -- warning even in Ada 2012 mode.
3467 or else Error_To_Warning
;
3474 -- Find matching actual
3476 Act
:= First_Actual
(N
);
3477 Form
:= First_Formal
(Subp
);
3478 while Act
/= Act2
loop
3483 if Is_Elementary_Type
(Etype
(Act1
))
3484 and then Ekind
(Form2
) = E_In_Parameter
3486 null; -- No real aliasing
3488 elsif Is_Elementary_Type
(Etype
(Act2
))
3489 and then Ekind
(Form2
) = E_In_Parameter
3493 -- If the call was written in prefix notation, and
3494 -- thus its prefix before rewriting was a selected
3495 -- component, count only visible actuals in the call.
3497 elsif Is_Entity_Name
(First_Actual
(N
))
3498 and then Nkind
(Original_Node
(N
)) = Nkind
(N
)
3499 and then Nkind
(Name
(Original_Node
(N
))) =
3500 N_Selected_Component
3502 Is_Entity_Name
(Prefix
(Name
(Original_Node
(N
))))
3504 Entity
(Prefix
(Name
(Original_Node
(N
)))) =
3505 Entity
(First_Actual
(N
))
3507 if Act1
= First_Actual
(N
) then
3509 ("<`IN OUT` prefix overlaps with "
3510 & "actual for&", Act1
, Form
);
3513 -- For greater clarity, give name of formal
3515 Error_Msg_Node_2
:= Form
;
3517 ("<writable actual for & overlaps with "
3518 & "actual for&", Act1
, Form
);
3522 -- For greater clarity, give name of formal
3524 Error_Msg_Node_2
:= Form
;
3526 -- This is one of the messages
3529 ("<writable actual for & overlaps with "
3530 & "actual for&", Act1
, Form1
);
3538 Next_Formal
(Form2
);
3543 Next_Formal
(Form1
);
3546 end Warn_On_Overlapping_Actuals
;
3548 ------------------------------
3549 -- Warn_On_Suspicious_Index --
3550 ------------------------------
3552 procedure Warn_On_Suspicious_Index
(Name
: Entity_Id
; X
: Node_Id
) is
3555 -- Set to lower bound for a suspicious type
3558 -- Entity for array reference
3563 function Is_Suspicious_Type
(Typ
: Entity_Id
) return Boolean;
3564 -- Tests to see if Typ is a type for which we may have a suspicious
3565 -- index, namely an unconstrained array type, whose lower bound is
3566 -- either zero or one. If so, True is returned, and Low_Bound is set
3567 -- to this lower bound. If not, False is returned, and Low_Bound is
3568 -- undefined on return.
3570 -- For now, we limit this to standard string types, so any other
3571 -- unconstrained types return False. We may change our minds on this
3572 -- later on, but strings seem the most important case.
3574 procedure Test_Suspicious_Index
;
3575 -- Test if index is of suspicious type and if so, generate warning
3577 ------------------------
3578 -- Is_Suspicious_Type --
3579 ------------------------
3581 function Is_Suspicious_Type
(Typ
: Entity_Id
) return Boolean is
3585 if Is_Array_Type
(Typ
)
3586 and then not Is_Constrained
(Typ
)
3587 and then Number_Dimensions
(Typ
) = 1
3588 and then (Root_Type
(Typ
) = Standard_String
3590 Root_Type
(Typ
) = Standard_Wide_String
3592 Root_Type
(Typ
) = Standard_Wide_Wide_String
)
3593 and then not Has_Warnings_Off
(Typ
)
3595 LB
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3597 if Compile_Time_Known_Value
(LB
) then
3598 Low_Bound
:= Expr_Value
(LB
);
3599 return Low_Bound
= Uint_0
or else Low_Bound
= Uint_1
;
3604 end Is_Suspicious_Type
;
3606 ---------------------------
3607 -- Test_Suspicious_Index --
3608 ---------------------------
3610 procedure Test_Suspicious_Index
is
3612 function Length_Reference
(N
: Node_Id
) return Boolean;
3613 -- Check if node N is of the form Name'Length
3616 -- Generate first warning line
3618 ----------------------
3619 -- Length_Reference --
3620 ----------------------
3622 function Length_Reference
(N
: Node_Id
) return Boolean is
3623 R
: constant Node_Id
:= Original_Node
(N
);
3626 Nkind
(R
) = N_Attribute_Reference
3627 and then Attribute_Name
(R
) = Name_Length
3628 and then Is_Entity_Name
(Prefix
(R
))
3629 and then Entity
(Prefix
(R
)) = Ent
;
3630 end Length_Reference
;
3638 Error_Msg_Uint_1
:= Low_Bound
;
3639 Error_Msg_FE
-- CODEFIX
3640 ("?w?index for& may assume lower bound of^", X
, Ent
);
3643 -- Start of processing for Test_Suspicious_Index
3646 -- Nothing to do if subscript does not come from source (we don't
3647 -- want to give garbage warnings on compiler expanded code, e.g. the
3648 -- loops generated for slice assignments. Such junk warnings would
3649 -- be placed on source constructs with no subscript in sight).
3651 if not Comes_From_Source
(Original_Node
(X
)) then
3655 -- Case where subscript is a constant integer
3657 if Nkind
(X
) = N_Integer_Literal
then
3660 -- Case where original form of subscript is an integer literal
3662 if Nkind
(Original_Node
(X
)) = N_Integer_Literal
then
3663 if Intval
(X
) = Low_Bound
then
3664 Error_Msg_FE
-- CODEFIX
3665 ("\?w?suggested replacement: `&''First`", X
, Ent
);
3667 Error_Msg_Uint_1
:= Intval
(X
) - Low_Bound
;
3668 Error_Msg_FE
-- CODEFIX
3669 ("\?w?suggested replacement: `&''First + ^`", X
, Ent
);
3673 -- Case where original form of subscript is more complex
3676 -- Build string X'First - 1 + expression where the expression
3677 -- is the original subscript. If the expression starts with "1
3678 -- + ", then the "- 1 + 1" is elided.
3680 Error_Msg_String
(1 .. 13) := "'First - 1 + ";
3681 Error_Msg_Strlen
:= 13;
3684 Sref
: Source_Ptr
:= Sloc
(First_Node
(Original_Node
(X
)));
3685 Tref
: constant Source_Buffer_Ptr
:=
3686 Source_Text
(Get_Source_File_Index
(Sref
));
3687 -- Tref (Sref) is used to scan the subscript
3690 -- Parentheses counter when scanning subscript
3693 -- Tref (Sref) points to start of subscript
3695 -- Elide - 1 if subscript starts with 1 +
3697 if Tref
(Sref
.. Sref
+ 2) = "1 +" then
3698 Error_Msg_Strlen
:= Error_Msg_Strlen
- 6;
3701 elsif Tref
(Sref
.. Sref
+ 1) = "1+" then
3702 Error_Msg_Strlen
:= Error_Msg_Strlen
- 6;
3706 -- Now we will copy the subscript to the string buffer
3710 -- Count parens, exit if terminating right paren. Note
3711 -- check to ignore paren appearing as character literal.
3713 if Tref
(Sref
+ 1) = '''
3715 Tref
(Sref
- 1) = '''
3719 if Tref
(Sref
) = '(' then
3721 elsif Tref
(Sref
) = ')' then
3727 -- Done if terminating double dot (slice case)
3730 and then (Tref
(Sref
.. Sref
+ 1) = ".."
3732 Tref
(Sref
.. Sref
+ 2) = " ..");
3734 -- Quit if we have hit EOF character, something wrong
3736 if Tref
(Sref
) = EOF
then
3740 -- String literals are too much of a pain to handle
3742 if Tref
(Sref
) = '"' or else Tref
(Sref
) = '%' then
3746 -- If we have a 'Range reference, then this is a case
3747 -- where we cannot easily give a replacement. Don't try.
3749 if Tref
(Sref
.. Sref
+ 4) = "range"
3750 and then Tref
(Sref
- 1) < 'A'
3751 and then Tref
(Sref
+ 5) < 'A'
3756 -- Else store next character
3758 Error_Msg_Strlen
:= Error_Msg_Strlen
+ 1;
3759 Error_Msg_String
(Error_Msg_Strlen
) := Tref
(Sref
);
3762 -- If we get more than 40 characters then the expression
3763 -- is too long to copy, or something has gone wrong. In
3764 -- either case, just skip the attempt at a suggested fix.
3766 if Error_Msg_Strlen
> 40 then
3772 -- Replacement subscript is now in string buffer
3774 Error_Msg_FE
-- CODEFIX
3775 ("\?w?suggested replacement: `&~`", Original_Node
(X
), Ent
);
3778 -- Case where subscript is of the form X'Length
3780 elsif Length_Reference
(X
) then
3782 Error_Msg_Node_2
:= Ent
;
3784 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3787 -- Case where subscript is of the form X'Length - expression
3789 elsif Nkind
(X
) = N_Op_Subtract
3790 and then Length_Reference
(Left_Opnd
(X
))
3793 Error_Msg_Node_2
:= Ent
;
3795 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3796 Left_Opnd
(X
), Ent
);
3798 end Test_Suspicious_Index
;
3800 -- Start of processing for Warn_On_Suspicious_Index
3803 -- Only process if warnings activated
3805 if Warn_On_Assumed_Low_Bound
then
3807 -- Test if array is simple entity name
3809 if Is_Entity_Name
(Name
) then
3811 -- Test if array is parameter of unconstrained string type
3813 Ent
:= Entity
(Name
);
3817 and then Is_Suspicious_Type
(Typ
)
3818 and then not Low_Bound_Tested
(Ent
)
3820 Test_Suspicious_Index
;
3824 end Warn_On_Suspicious_Index
;
3826 --------------------------------------
3827 -- Warn_On_Unassigned_Out_Parameter --
3828 --------------------------------------
3830 procedure Warn_On_Unassigned_Out_Parameter
3831 (Return_Node
: Node_Id
;
3832 Scope_Id
: Entity_Id
)
3838 -- Ignore if procedure or return statement does not come from source
3840 if not Comes_From_Source
(Scope_Id
)
3841 or else not Comes_From_Source
(Return_Node
)
3846 -- Loop through formals
3848 Form
:= First_Formal
(Scope_Id
);
3849 while Present
(Form
) loop
3851 -- We are only interested in OUT parameters that come from source
3852 -- and are never set in the source, and furthermore only in scalars
3853 -- since non-scalars generate too many false positives.
3855 if Ekind
(Form
) = E_Out_Parameter
3856 and then Never_Set_In_Source_Check_Spec
(Form
)
3857 and then Is_Scalar_Type
(Etype
(Form
))
3858 and then not Present
(Unset_Reference
(Form
))
3860 -- Before we issue the warning, an add ad hoc defence against the
3861 -- most common case of false positives with this warning which is
3862 -- the case where there is a Boolean OUT parameter that has been
3863 -- set, and whose meaning is "ignore the values of the other
3864 -- parameters". We can't of course reliably tell this case at
3865 -- compile time, but the following test kills a lot of false
3866 -- positives, without generating a significant number of false
3867 -- negatives (missed real warnings).
3869 Form2
:= First_Formal
(Scope_Id
);
3870 while Present
(Form2
) loop
3871 if Ekind
(Form2
) = E_Out_Parameter
3872 and then Root_Type
(Etype
(Form2
)) = Standard_Boolean
3873 and then not Never_Set_In_Source_Check_Spec
(Form2
)
3878 Next_Formal
(Form2
);
3881 -- Here all conditions are met, record possible unset reference
3883 Set_Unset_Reference
(Form
, Return_Node
);
3888 end Warn_On_Unassigned_Out_Parameter
;
3890 ---------------------------------
3891 -- Warn_On_Unreferenced_Entity --
3892 ---------------------------------
3894 procedure Warn_On_Unreferenced_Entity
3895 (Spec_E
: Entity_Id
;
3896 Body_E
: Entity_Id
:= Empty
)
3898 E
: Entity_Id
:= Spec_E
;
3901 if not Referenced_Check_Spec
(E
)
3902 and then not Has_Pragma_Unreferenced_Check_Spec
(E
)
3903 and then not Warnings_Off_Check_Spec
(E
)
3904 and then not Is_Junk_Name
(Chars
(Spec_E
))
3909 -- Case of variable that is assigned but not read. We suppress
3910 -- the message if the variable is volatile, has an address
3911 -- clause, is aliased, or is a renaming, or is imported.
3913 if Referenced_As_LHS_Check_Spec
(E
)
3914 and then No
(Address_Clause
(E
))
3915 and then not Is_Volatile
(E
)
3917 if Warn_On_Modified_Unread
3918 and then not Is_Imported
(E
)
3919 and then not Is_Aliased
(E
)
3920 and then No
(Renamed_Object
(E
))
3922 if not Has_Pragma_Unmodified_Check_Spec
(E
) then
3923 Error_Msg_N
-- CODEFIX
3924 ("?u?variable & is assigned but never read!", E
);
3927 Set_Last_Assignment
(E
, Empty
);
3930 -- Normal case of neither assigned nor read (exclude variables
3931 -- referenced as out parameters, since we already generated
3932 -- appropriate warnings at the call point in this case).
3934 elsif not Referenced_As_Out_Parameter
(E
) then
3936 -- We suppress the message for types for which a valid
3937 -- pragma Unreferenced_Objects has been given, otherwise
3938 -- we go ahead and give the message.
3940 if not Has_Pragma_Unreferenced_Objects
(Etype
(E
)) then
3942 -- Distinguish renamed case in message
3944 if Present
(Renamed_Object
(E
))
3945 and then Comes_From_Source
(Renamed_Object
(E
))
3947 Error_Msg_N
-- CODEFIX
3948 ("?u?renamed variable & is not referenced!", E
);
3950 Error_Msg_N
-- CODEFIX
3951 ("?u?variable & is not referenced!", E
);
3957 if Present
(Renamed_Object
(E
))
3958 and then Comes_From_Source
(Renamed_Object
(E
))
3960 Error_Msg_N
-- CODEFIX
3961 ("?u?renamed constant & is not referenced!", E
);
3963 Error_Msg_N
-- CODEFIX
3964 ("?u?constant & is not referenced!", E
);
3967 when E_In_Parameter |
3968 E_In_Out_Parameter
=>
3970 -- Do not emit message for formals of a renaming, because
3971 -- they are never referenced explicitly.
3973 if Nkind
(Original_Node
(Unit_Declaration_Node
(Scope
(E
)))) /=
3974 N_Subprogram_Renaming_Declaration
3976 -- Suppress this message for an IN OUT parameter of a
3977 -- non-scalar type, since it is normal to have only an
3978 -- assignment in such a case.
3980 if Ekind
(E
) = E_In_Parameter
3981 or else not Referenced_As_LHS_Check_Spec
(E
)
3982 or else Is_Scalar_Type
(Etype
(E
))
3984 if Present
(Body_E
) then
3988 if not Is_Trivial_Subprogram
(Scope
(E
)) then
3989 Error_Msg_NE
-- CODEFIX
3990 ("?u?formal parameter & is not referenced!",
3996 when E_Out_Parameter
=>
3999 when E_Discriminant
=>
4000 Error_Msg_N
("?u?discriminant & is not referenced!", E
);
4002 when E_Named_Integer |
4004 Error_Msg_N
-- CODEFIX
4005 ("?u?named number & is not referenced!", E
);
4007 when Formal_Object_Kind
=>
4008 Error_Msg_N
-- CODEFIX
4009 ("?u?formal object & is not referenced!", E
);
4011 when E_Enumeration_Literal
=>
4012 Error_Msg_N
-- CODEFIX
4013 ("?u?literal & is not referenced!", E
);
4016 Error_Msg_N
-- CODEFIX
4017 ("?u?function & is not referenced!", E
);
4020 Error_Msg_N
-- CODEFIX
4021 ("?u?procedure & is not referenced!", E
);
4024 Error_Msg_N
-- CODEFIX
4025 ("?u?package & is not referenced!", E
);
4028 Error_Msg_N
-- CODEFIX
4029 ("?u?exception & is not referenced!", E
);
4032 Error_Msg_N
-- CODEFIX
4033 ("?u?label & is not referenced!", E
);
4035 when E_Generic_Procedure
=>
4036 Error_Msg_N
-- CODEFIX
4037 ("?u?generic procedure & is never instantiated!", E
);
4039 when E_Generic_Function
=>
4040 Error_Msg_N
-- CODEFIX
4041 ("?u?generic function & is never instantiated!", E
);
4044 Error_Msg_N
-- CODEFIX
4045 ("?u?type & is not referenced!", E
);
4048 Error_Msg_N
-- CODEFIX
4049 ("?u?& is not referenced!", E
);
4052 -- Kill warnings on the entity on which the message has been posted
4054 Set_Warnings_Off
(E
);
4056 end Warn_On_Unreferenced_Entity
;
4058 --------------------------------
4059 -- Warn_On_Useless_Assignment --
4060 --------------------------------
4062 procedure Warn_On_Useless_Assignment
4064 N
: Node_Id
:= Empty
)
4069 function Check_Ref
(N
: Node_Id
) return Traverse_Result
;
4070 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4071 -- the entity in question is found.
4073 function Test_No_Refs
is new Traverse_Func
(Check_Ref
);
4079 function Check_Ref
(N
: Node_Id
) return Traverse_Result
is
4081 -- Check reference to our identifier. We use name equality here
4082 -- because the exception handlers have not yet been analyzed. This
4083 -- is not quite right, but it really does not matter that we fail
4084 -- to output the warning in some obscure cases of name clashes.
4086 if Nkind
(N
) = N_Identifier
4087 and then Chars
(N
) = Chars
(Ent
)
4095 -- Start of processing for Warn_On_Useless_Assignment
4098 -- Check if this is a case we want to warn on, a scalar or access
4099 -- variable with the last assignment field set, with warnings enabled,
4100 -- and which is not imported or exported. We also check that it is OK
4101 -- to capture the value. We are not going to capture any value, but
4102 -- the warning message depends on the same kind of conditions.
4104 if Is_Assignable
(Ent
)
4105 and then not Is_Return_Object
(Ent
)
4106 and then Present
(Last_Assignment
(Ent
))
4107 and then not Is_Imported
(Ent
)
4108 and then not Is_Exported
(Ent
)
4109 and then Safe_To_Capture_Value
(N
, Ent
)
4110 and then not Has_Pragma_Unreferenced_Check_Spec
(Ent
)
4111 and then not Is_Junk_Name
(Chars
(Ent
))
4113 -- Before we issue the message, check covering exception handlers.
4114 -- Search up tree for enclosing statement sequences and handlers.
4116 P
:= Parent
(Last_Assignment
(Ent
));
4117 while Present
(P
) loop
4119 -- Something is really wrong if we don't find a handled statement
4120 -- sequence, so just suppress the warning.
4123 Set_Last_Assignment
(Ent
, Empty
);
4126 -- When we hit a package/subprogram body, issue warning and exit
4128 elsif Nkind
(P
) = N_Subprogram_Body
4129 or else Nkind
(P
) = N_Package_Body
4131 -- Case of assigned value never referenced
4135 LA
: constant Node_Id
:= Last_Assignment
(Ent
);
4138 -- Don't give this for OUT and IN OUT formals, since
4139 -- clearly caller may reference the assigned value. Also
4140 -- never give such warnings for internal variables.
4142 if Ekind
(Ent
) = E_Variable
4143 and then not Is_Internal_Name
(Chars
(Ent
))
4145 -- Give appropriate message, distinguishing between
4146 -- assignment statements and out parameters.
4148 if Nkind_In
(Parent
(LA
), N_Procedure_Call_Statement
,
4149 N_Parameter_Association
)
4152 ("?m?& modified by call, but value never "
4153 & "referenced", LA
, Ent
);
4156 Error_Msg_NE
-- CODEFIX
4157 ("?m?useless assignment to&, value never "
4158 & "referenced!", LA
, Ent
);
4163 -- Case of assigned value overwritten
4167 LA
: constant Node_Id
:= Last_Assignment
(Ent
);
4170 Error_Msg_Sloc
:= Sloc
(N
);
4172 -- Give appropriate message, distinguishing between
4173 -- assignment statements and out parameters.
4175 if Nkind_In
(Parent
(LA
), N_Procedure_Call_Statement
,
4176 N_Parameter_Association
)
4179 ("?m?& modified by call, but value overwritten #!",
4182 Error_Msg_NE
-- CODEFIX
4183 ("?m?useless assignment to&, value overwritten #!",
4189 -- Clear last assignment indication and we are done
4191 Set_Last_Assignment
(Ent
, Empty
);
4194 -- Enclosing handled sequence of statements
4196 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
then
4198 -- Check exception handlers present
4200 if Present
(Exception_Handlers
(P
)) then
4202 -- If we are not at the top level, we regard an inner
4203 -- exception handler as a decisive indicator that we should
4204 -- not generate the warning, since the variable in question
4205 -- may be accessed after an exception in the outer block.
4207 if Nkind
(Parent
(P
)) /= N_Subprogram_Body
4208 and then Nkind
(Parent
(P
)) /= N_Package_Body
4210 Set_Last_Assignment
(Ent
, Empty
);
4213 -- Otherwise we are at the outer level. An exception
4214 -- handler is significant only if it references the
4215 -- variable in question, or if the entity in question
4216 -- is an OUT or IN OUT parameter, which which case
4217 -- the caller can reference it after the exception
4218 -- handler completes.
4221 if Is_Formal
(Ent
) then
4222 Set_Last_Assignment
(Ent
, Empty
);
4226 X
:= First
(Exception_Handlers
(P
));
4227 while Present
(X
) loop
4228 if Test_No_Refs
(X
) = Abandon
then
4229 Set_Last_Assignment
(Ent
, Empty
);
4243 end Warn_On_Useless_Assignment
;
4245 ---------------------------------
4246 -- Warn_On_Useless_Assignments --
4247 ---------------------------------
4249 procedure Warn_On_Useless_Assignments
(E
: Entity_Id
) is
4253 Process_Deferred_References
;
4255 if Warn_On_Modified_Unread
4256 and then In_Extended_Main_Source_Unit
(E
)
4258 Ent
:= First_Entity
(E
);
4259 while Present
(Ent
) loop
4260 Warn_On_Useless_Assignment
(Ent
);
4264 end Warn_On_Useless_Assignments
;
4266 -----------------------------
4267 -- Warnings_Off_Check_Spec --
4268 -----------------------------
4270 function Warnings_Off_Check_Spec
(E
: Entity_Id
) return Boolean is
4272 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
4274 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4275 -- to mess with flags on both entities.
4277 return Has_Warnings_Off
(E
)
4279 Has_Warnings_Off
(Spec_Entity
(E
));
4282 return Has_Warnings_Off
(E
);
4284 end Warnings_Off_Check_Spec
;