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 Namet
; use Namet
;
34 with Nlists
; use Nlists
;
36 with Par_SCO
; use Par_SCO
;
37 with Rtsfind
; use Rtsfind
;
39 with Sem_Ch8
; use Sem_Ch8
;
40 with Sem_Aux
; use Sem_Aux
;
41 with Sem_Eval
; use Sem_Eval
;
42 with Sem_Util
; use Sem_Util
;
43 with Sinfo
; use Sinfo
;
44 with Sinput
; use Sinput
;
45 with Snames
; use Snames
;
46 with Stand
; use Stand
;
47 with Stringt
; use Stringt
;
48 with Uintp
; use Uintp
;
50 package body Sem_Warn
is
52 -- The following table collects Id's of entities that are potentially
53 -- unreferenced. See Check_Unset_Reference for further details.
54 -- ??? Check_Unset_Reference has zero information about this table.
56 package Unreferenced_Entities
is new Table
.Table
(
57 Table_Component_Type
=> Entity_Id
,
58 Table_Index_Type
=> Nat
,
60 Table_Initial
=> Alloc
.Unreferenced_Entities_Initial
,
61 Table_Increment
=> Alloc
.Unreferenced_Entities_Increment
,
62 Table_Name
=> "Unreferenced_Entities");
64 -- The following table collects potential warnings for IN OUT parameters
65 -- that are referenced but not modified. These warnings are processed when
66 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
67 -- The reason that we defer output of these messages is that we want to
68 -- detect the case where the relevant procedure is used as a generic actual
69 -- in an instantiation, since we suppress the warnings in this case. The
70 -- flag Used_As_Generic_Actual will be set in this case, but only at the
71 -- point of usage. Similarly, we suppress the message if the address of the
72 -- procedure is taken, where the flag Address_Taken may be set later.
74 package In_Out_Warnings
is new Table
.Table
(
75 Table_Component_Type
=> Entity_Id
,
76 Table_Index_Type
=> Nat
,
78 Table_Initial
=> Alloc
.In_Out_Warnings_Initial
,
79 Table_Increment
=> Alloc
.In_Out_Warnings_Increment
,
80 Table_Name
=> "In_Out_Warnings");
82 --------------------------------------------------------
83 -- Handling of Warnings Off, Unmodified, Unreferenced --
84 --------------------------------------------------------
86 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
87 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
88 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
90 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
91 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
92 -- must follow some important rules.
94 -- Call these functions as late as possible, after completing all other
95 -- tests, just before the warnings is given. For example, don't write:
97 -- if not Has_Warnings_Off (E)
98 -- and then some-other-predicate-on-E then ..
100 -- Instead the following is preferred
102 -- if some-other-predicate-on-E
103 -- and then Has_Warnings_Off (E)
105 -- This way if some-other-predicate is false, we avoid a false indication
106 -- that a Warnings (Off, E) pragma was useful in preventing a warning.
108 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
109 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
110 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
111 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
112 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
113 -- and so a subsequent test is not needed anyway (though it is harmless).
115 -----------------------
116 -- Local Subprograms --
117 -----------------------
119 function Generic_Package_Spec_Entity
(E
: Entity_Id
) return Boolean;
120 -- This returns true if the entity E is declared within a generic package.
121 -- The point of this is to detect variables which are not assigned within
122 -- the generic, but might be assigned outside the package for any given
123 -- instance. These are cases where we leave the warnings to be posted for
124 -- the instance, when we will know more.
126 function Goto_Spec_Entity
(E
: Entity_Id
) return Entity_Id
;
127 -- If E is a parameter entity for a subprogram body, then this function
128 -- returns the corresponding spec entity, if not, E is returned unchanged.
130 function Has_Pragma_Unmodified_Check_Spec
(E
: Entity_Id
) return Boolean;
131 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
132 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
133 -- a body formal, the setting of the flag in the corresponding spec is
134 -- also checked (and True returned if either flag is True).
136 function Has_Pragma_Unreferenced_Check_Spec
(E
: Entity_Id
) return Boolean;
137 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
138 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
139 -- a body formal, the setting of the flag in the corresponding spec is
140 -- also checked (and True returned if either flag is True).
142 function Never_Set_In_Source_Check_Spec
(E
: Entity_Id
) return Boolean;
143 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
144 -- this is simply the setting of the flag Never_Set_In_Source. If E is
145 -- a body formal, the setting of the flag in the corresponding spec is
146 -- also checked (and False returned if either flag is False).
148 function Operand_Has_Warnings_Suppressed
(N
: Node_Id
) return Boolean;
149 -- This function traverses the expression tree represented by the node N
150 -- and determines if any sub-operand is a reference to an entity for which
151 -- the Warnings_Off flag is set. True is returned if such an entity is
152 -- encountered, and False otherwise.
154 function Referenced_Check_Spec
(E
: Entity_Id
) return Boolean;
155 -- Tests Referenced status for entity E. If E is not a formal, this is
156 -- simply the setting of the flag Referenced. If E is a body formal, the
157 -- setting of the flag in the corresponding spec is also checked (and True
158 -- returned if either flag is True).
160 function Referenced_As_LHS_Check_Spec
(E
: Entity_Id
) return Boolean;
161 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
162 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
163 -- formal, the setting of the flag in the corresponding spec is also
164 -- checked (and True returned if either flag is True).
166 function Referenced_As_Out_Parameter_Check_Spec
167 (E
: Entity_Id
) return Boolean;
168 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
169 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
170 -- is a body formal, the setting of the flag in the corresponding spec is
171 -- also checked (and True returned if either flag is True).
173 procedure Warn_On_Unreferenced_Entity
175 Body_E
: Entity_Id
:= Empty
);
176 -- Output warnings for unreferenced entity E. For the case of an entry
177 -- formal, Body_E is the corresponding body entity for a particular
178 -- accept statement, and the message is posted on Body_E. In all other
179 -- cases, Body_E is ignored and must be Empty.
181 function Warnings_Off_Check_Spec
(E
: Entity_Id
) return Boolean;
182 -- Returns True if Warnings_Off is set for the entity E or (in the case
183 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
185 --------------------------
186 -- Check_Code_Statement --
187 --------------------------
189 procedure Check_Code_Statement
(N
: Node_Id
) is
191 -- If volatile, nothing to worry about
193 if Is_Asm_Volatile
(N
) then
197 -- Warn if no input or no output
199 Setup_Asm_Inputs
(N
);
201 if No
(Asm_Input_Value
) then
203 ("??code statement with no inputs should usually be Volatile!", N
);
207 Setup_Asm_Outputs
(N
);
209 if No
(Asm_Output_Variable
) then
211 ("??code statement with no outputs should usually be Volatile!", N
);
214 end Check_Code_Statement
;
216 ---------------------------------
217 -- Check_Infinite_Loop_Warning --
218 ---------------------------------
220 -- The case we look for is a while loop which tests a local variable, where
221 -- there is no obvious direct or possible indirect update of the variable
222 -- within the body of the loop.
224 procedure Check_Infinite_Loop_Warning
(Loop_Statement
: Node_Id
) is
225 Expression
: Node_Id
:= Empty
;
226 -- Set to WHILE or EXIT WHEN condition to be tested
228 Ref
: Node_Id
:= Empty
;
229 -- Reference in Expression to variable that might not be modified
230 -- in loop, indicating a possible infinite loop.
232 Var
: Entity_Id
:= Empty
;
233 -- Corresponding entity (entity of Ref)
235 Function_Call_Found
: Boolean := False;
236 -- True if Find_Var found a function call in the condition
238 procedure Find_Var
(N
: Node_Id
);
239 -- Inspect condition to see if it depends on a single entity reference.
240 -- If so, Ref is set to point to the reference node, and Var is set to
241 -- the referenced Entity.
243 function Has_Indirection
(T
: Entity_Id
) return Boolean;
244 -- If the controlling variable is an access type, or is a record type
245 -- with access components, assume that it is changed indirectly and
246 -- suppress the warning. As a concession to low-level programming, in
247 -- particular within Declib, we also suppress warnings on a record
248 -- type that contains components of type Address or Short_Address.
250 function Is_Suspicious_Function_Name
(E
: Entity_Id
) return Boolean;
251 -- Given an entity name, see if the name appears to have something to
252 -- do with I/O or network stuff, and if so, return True. Used to kill
253 -- some false positives on a heuristic basis that such functions will
254 -- likely have some strange side effect dependencies. A rather funny
255 -- kludge, but warning messages are in the heuristics business.
257 function Test_Ref
(N
: Node_Id
) return Traverse_Result
;
258 -- Test for reference to variable in question. Returns Abandon if
259 -- matching reference found. Used in instantiation of No_Ref_Found.
261 function No_Ref_Found
is new Traverse_Func
(Test_Ref
);
262 -- Function to traverse body of procedure. Returns Abandon if matching
269 procedure Find_Var
(N
: Node_Id
) is
271 -- Condition is a direct variable reference
273 if Is_Entity_Name
(N
) then
277 -- Case of condition is a comparison with compile time known value
279 elsif Nkind
(N
) in N_Op_Compare
then
280 if Compile_Time_Known_Value
(Right_Opnd
(N
)) then
281 Find_Var
(Left_Opnd
(N
));
283 elsif Compile_Time_Known_Value
(Left_Opnd
(N
)) then
284 Find_Var
(Right_Opnd
(N
));
286 -- Ignore any other comparison
292 -- If condition is a negation, check its operand
294 elsif Nkind
(N
) = N_Op_Not
then
295 Find_Var
(Right_Opnd
(N
));
297 -- Case of condition is function call
299 elsif Nkind
(N
) = N_Function_Call
then
301 Function_Call_Found
:= True;
303 -- Forget it if function name is not entity, who knows what
304 -- we might be calling?
306 if not Is_Entity_Name
(Name
(N
)) then
309 -- Forget it if function name is suspicious. A strange test
310 -- but warning generation is in the heuristics business.
312 elsif Is_Suspicious_Function_Name
(Entity
(Name
(N
))) then
315 -- Forget it if warnings are suppressed on function entity
317 elsif Has_Warnings_Off
(Entity
(Name
(N
))) then
321 -- OK, see if we have one argument
324 PA
: constant List_Id
:= Parameter_Associations
(N
);
327 -- One argument, so check the argument
330 and then List_Length
(PA
) = 1
332 if Nkind
(First
(PA
)) = N_Parameter_Association
then
333 Find_Var
(Explicit_Actual_Parameter
(First
(PA
)));
335 Find_Var
(First
(PA
));
345 -- Any other kind of node is not something we warn for
352 ---------------------
353 -- Has_Indirection --
354 ---------------------
356 function Has_Indirection
(T
: Entity_Id
) return Boolean is
361 if Is_Access_Type
(T
) then
364 elsif Is_Private_Type
(T
)
365 and then Present
(Full_View
(T
))
366 and then Is_Access_Type
(Full_View
(T
))
370 elsif Is_Record_Type
(T
) then
373 elsif Is_Private_Type
(T
)
374 and then Present
(Full_View
(T
))
375 and then Is_Record_Type
(Full_View
(T
))
377 Rec
:= Full_View
(T
);
382 Comp
:= First_Component
(Rec
);
383 while Present
(Comp
) loop
384 if Is_Access_Type
(Etype
(Comp
))
385 or else Is_Descendent_Of_Address
(Etype
(Comp
))
390 Next_Component
(Comp
);
396 ---------------------------------
397 -- Is_Suspicious_Function_Name --
398 ---------------------------------
400 function Is_Suspicious_Function_Name
(E
: Entity_Id
) return Boolean is
403 function Substring_Present
(S
: String) return Boolean;
404 -- Returns True if name buffer has given string delimited by non-
405 -- alphabetic characters or by end of string. S is lower case.
407 -----------------------
408 -- Substring_Present --
409 -----------------------
411 function Substring_Present
(S
: String) return Boolean is
412 Len
: constant Natural := S
'Length;
415 for J
in 1 .. Name_Len
- (Len
- 1) loop
416 if Name_Buffer
(J
.. J
+ (Len
- 1)) = S
419 or else Name_Buffer
(J
- 1) not in 'a' .. 'z')
422 or else Name_Buffer
(J
+ Len
) not in 'a' .. 'z')
429 end Substring_Present
;
431 -- Start of processing for Is_Suspicious_Function_Name
435 while Present
(S
) and then S
/= Standard_Standard
loop
436 Get_Name_String
(Chars
(S
));
438 if Substring_Present
("io")
439 or else Substring_Present
("file")
440 or else Substring_Present
("network")
449 end Is_Suspicious_Function_Name
;
455 function Test_Ref
(N
: Node_Id
) return Traverse_Result
is
457 -- Waste of time to look at the expression we are testing
459 if N
= Expression
then
462 -- Direct reference to variable in question
464 elsif Is_Entity_Name
(N
)
465 and then Present
(Entity
(N
))
466 and then Entity
(N
) = Var
468 -- If this is an lvalue, then definitely abandon, since
469 -- this could be a direct modification of the variable.
471 if May_Be_Lvalue
(N
) then
475 -- If the condition contains a function call, we consider it may
476 -- be modified by side-effects from a procedure call. Otherwise,
477 -- we consider the condition may not be modified, although that
478 -- might happen if Variable is itself a by-reference parameter,
479 -- and the procedure called modifies the global object referred to
480 -- by Variable, but we actually prefer to issue a warning in this
481 -- odd case. Note that the case where the procedure called has
482 -- visibility over Variable is treated in another case below.
484 if Function_Call_Found
then
492 exit when P
= Loop_Statement
;
494 -- Abandon if at procedure call, or something strange is
495 -- going on (perhaps a node with no parent that should
496 -- have one but does not?) As always, for a warning we
497 -- prefer to just abandon the warning than get into the
498 -- business of complaining about the tree structure here.
501 or else Nkind
(P
) = N_Procedure_Call_Statement
509 -- Reference to variable renaming variable in question
511 elsif Is_Entity_Name
(N
)
512 and then Present
(Entity
(N
))
513 and then Ekind
(Entity
(N
)) = E_Variable
514 and then Present
(Renamed_Object
(Entity
(N
)))
515 and then Is_Entity_Name
(Renamed_Object
(Entity
(N
)))
516 and then Entity
(Renamed_Object
(Entity
(N
))) = Var
517 and then May_Be_Lvalue
(N
)
521 -- Call to subprogram
523 elsif Nkind
(N
) in N_Subprogram_Call
then
525 -- If subprogram is within the scope of the entity we are dealing
526 -- with as the loop variable, then it could modify this parameter,
527 -- so we abandon in this case. In the case of a subprogram that is
528 -- not an entity we also abandon. The check for no entity being
529 -- present is a defense against previous errors.
531 if not Is_Entity_Name
(Name
(N
))
532 or else No
(Entity
(Name
(N
)))
533 or else Scope_Within
(Entity
(Name
(N
)), Scope
(Var
))
538 -- If any of the arguments are of type access to subprogram, then
539 -- we may have funny side effects, so no warning in this case.
544 Actual
:= First_Actual
(N
);
545 while Present
(Actual
) loop
546 if Is_Access_Subprogram_Type
(Etype
(Actual
)) then
549 Next_Actual
(Actual
);
554 -- Declaration of the variable in question
556 elsif Nkind
(N
) = N_Object_Declaration
557 and then Defining_Identifier
(N
) = Var
562 -- All OK, continue scan
567 -- Start of processing for Check_Infinite_Loop_Warning
570 -- Skip processing if debug flag gnatd.w is set
572 if Debug_Flag_Dot_W
then
576 -- Deal with Iteration scheme present
579 Iter
: constant Node_Id
:= Iteration_Scheme
(Loop_Statement
);
582 if Present
(Iter
) then
586 if Present
(Condition
(Iter
)) then
588 -- Skip processing for while iteration with conditions actions,
589 -- since they make it too complicated to get the warning right.
591 if Present
(Condition_Actions
(Iter
)) then
595 -- Capture WHILE condition
597 Expression
:= Condition
(Iter
);
599 -- For iteration, do not process, since loop will always terminate
601 elsif Present
(Loop_Parameter_Specification
(Iter
)) then
607 -- Check chain of EXIT statements, we only process loops that have a
608 -- single exit condition (either a single EXIT WHEN statement, or a
609 -- WHILE loop not containing any EXIT WHEN statements).
612 Ident
: constant Node_Id
:= Identifier
(Loop_Statement
);
616 -- If we don't have a proper chain set, ignore call entirely. This
617 -- happens because of previous errors.
619 if No
(Entity
(Ident
))
620 or else Ekind
(Entity
(Ident
)) /= E_Loop
622 Check_Error_Detected
;
626 -- Otherwise prepare to scan list of EXIT statements
628 Exit_Stmt
:= First_Exit_Statement
(Entity
(Ident
));
629 while Present
(Exit_Stmt
) loop
631 -- Check for EXIT WHEN
633 if Present
(Condition
(Exit_Stmt
)) then
635 -- Quit processing if EXIT WHEN in WHILE loop, or more than
636 -- one EXIT WHEN statement present in the loop.
638 if Present
(Expression
) then
641 -- Otherwise capture condition from EXIT WHEN statement
644 Expression
:= Condition
(Exit_Stmt
);
647 -- If an unconditional exit statement is the last statement in the
648 -- loop, assume that no warning is needed, without any attempt at
649 -- checking whether the exit is reachable.
651 elsif Exit_Stmt
= Last
(Statements
(Loop_Statement
)) then
655 Exit_Stmt
:= Next_Exit_Statement
(Exit_Stmt
);
659 -- Return if no condition to test
661 if No
(Expression
) then
665 -- Initial conditions met, see if condition is of right form
667 Find_Var
(Expression
);
669 -- Nothing to do if local variable from source not found. If it's a
670 -- renaming, it is probably renaming something too complicated to deal
674 or else Ekind
(Var
) /= E_Variable
675 or else Is_Library_Level_Entity
(Var
)
676 or else not Comes_From_Source
(Var
)
677 or else Nkind
(Parent
(Var
)) = N_Object_Renaming_Declaration
681 -- Nothing to do if there is some indirection involved (assume that the
682 -- designated variable might be modified in some way we don't see).
683 -- However, if no function call was found, then we don't care about
684 -- indirections, because the condition must be something like "while X
685 -- /= null loop", so we don't care if X.all is modified in the loop.
687 elsif Function_Call_Found
and then Has_Indirection
(Etype
(Var
)) then
690 -- Same sort of thing for volatile variable, might be modified by
691 -- some other task or by the operating system in some way.
693 elsif Is_Volatile
(Var
) then
697 -- Filter out case of original statement sequence starting with delay.
698 -- We assume this is a multi-tasking program and that the condition
699 -- is affected by other threads (some kind of busy wait).
702 Fstm
: constant Node_Id
:=
703 Original_Node
(First
(Statements
(Loop_Statement
)));
705 if Nkind
(Fstm
) = N_Delay_Relative_Statement
706 or else Nkind
(Fstm
) = N_Delay_Until_Statement
712 -- We have a variable reference of the right form, now we scan the loop
713 -- body to see if it looks like it might not be modified
715 if No_Ref_Found
(Loop_Statement
) = OK
then
717 ("??variable& is not modified in loop body!", Ref
, Var
);
719 ("\??possible infinite loop!", Ref
);
721 end Check_Infinite_Loop_Warning
;
723 ----------------------------
724 -- Check_Low_Bound_Tested --
725 ----------------------------
727 procedure Check_Low_Bound_Tested
(Expr
: Node_Id
) is
729 if Comes_From_Source
(Expr
) then
731 L
: constant Node_Id
:= Left_Opnd
(Expr
);
732 R
: constant Node_Id
:= Right_Opnd
(Expr
);
734 if Nkind
(L
) = N_Attribute_Reference
735 and then Attribute_Name
(L
) = Name_First
736 and then Is_Entity_Name
(Prefix
(L
))
737 and then Is_Formal
(Entity
(Prefix
(L
)))
739 Set_Low_Bound_Tested
(Entity
(Prefix
(L
)));
742 if Nkind
(R
) = N_Attribute_Reference
743 and then Attribute_Name
(R
) = Name_First
744 and then Is_Entity_Name
(Prefix
(R
))
745 and then Is_Formal
(Entity
(Prefix
(R
)))
747 Set_Low_Bound_Tested
(Entity
(Prefix
(R
)));
751 end Check_Low_Bound_Tested
;
753 ----------------------
754 -- Check_References --
755 ----------------------
757 procedure Check_References
(E
: Entity_Id
; Anod
: Node_Id
:= Empty
) is
764 Accept_Statement
: Node_Id
) return Entity_Id
;
765 -- For an entry formal entity from an entry declaration, find the
766 -- corresponding body formal from the given accept statement.
768 function Missing_Subunits
return Boolean;
769 -- We suppress warnings when there are missing subunits, because this
770 -- may generate too many false positives: entities in a parent may only
771 -- be referenced in one of the subunits. We make an exception for
772 -- subunits that contain no other stubs.
774 procedure Output_Reference_Error
(M
: String);
775 -- Used to output an error message. Deals with posting the error on the
776 -- body formal in the accept case.
778 function Publicly_Referenceable
(Ent
: Entity_Id
) return Boolean;
779 -- This is true if the entity in question is potentially referenceable
780 -- from another unit. This is true for entities in packages that are at
781 -- the library level.
783 function Warnings_Off_E1
return Boolean;
784 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
785 -- or for the base type of E1T.
793 Accept_Statement
: Node_Id
) return Entity_Id
795 Body_Param
: Node_Id
;
799 -- Loop to find matching parameter in accept statement
801 Body_Param
:= First
(Parameter_Specifications
(Accept_Statement
));
802 while Present
(Body_Param
) loop
803 Body_E
:= Defining_Identifier
(Body_Param
);
805 if Chars
(Body_E
) = Chars
(E
) then
812 -- Should never fall through, should always find a match
817 ----------------------
818 -- Missing_Subunits --
819 ----------------------
821 function Missing_Subunits
return Boolean is
825 if not Unloaded_Subunits
then
827 -- Normal compilation, all subunits are present
831 elsif E
/= Main_Unit_Entity
then
833 -- No warnings on a stub that is not the main unit
837 elsif Nkind
(Unit_Declaration_Node
(E
)) in N_Proper_Body
then
838 D
:= First
(Declarations
(Unit_Declaration_Node
(E
)));
839 while Present
(D
) loop
841 -- No warnings if the proper body contains nested stubs
843 if Nkind
(D
) in N_Body_Stub
then
853 -- Missing stubs elsewhere
857 end Missing_Subunits
;
859 ----------------------------
860 -- Output_Reference_Error --
861 ----------------------------
863 procedure Output_Reference_Error
(M
: String) is
865 -- Never issue messages for internal names, nor for renamings
867 if Is_Internal_Name
(Chars
(E1
))
868 or else Nkind
(Parent
(E1
)) = N_Object_Renaming_Declaration
873 -- Don't output message for IN OUT formal unless we have the warning
874 -- flag specifically set. It is a bit odd to distinguish IN OUT
875 -- formals from other cases. This distinction is historical in
876 -- nature. Warnings for IN OUT formals were added fairly late.
878 if Ekind
(E1
) = E_In_Out_Parameter
879 and then not Check_Unreferenced_Formals
884 -- Other than accept case, post error on defining identifier
889 -- Accept case, find body formal to post the message
892 Error_Msg_NE
(M
, Body_Formal
(E1
, Accept_Statement
=> Anod
), E1
);
895 end Output_Reference_Error
;
897 ----------------------------
898 -- Publicly_Referenceable --
899 ----------------------------
901 function Publicly_Referenceable
(Ent
: Entity_Id
) return Boolean is
906 -- A formal parameter is never referenceable outside the body of its
907 -- subprogram or entry.
909 if Is_Formal
(Ent
) then
913 -- Examine parents to look for a library level package spec. But if
914 -- we find a body or block or other similar construct along the way,
915 -- we cannot be referenced.
922 -- If we get to top of tree, then publicly referenceable
927 -- If we reach a generic package declaration, then always
928 -- consider this referenceable, since any instantiation will
929 -- have access to the entities in the generic package. Note
930 -- that the package itself may not be instantiated, but then
931 -- we will get a warning for the package entity.
933 -- Note that generic formal parameters are themselves not
934 -- publicly referenceable in an instance, and warnings on them
937 when N_Generic_Package_Declaration
=>
939 not Is_List_Member
(Prev
)
940 or else List_Containing
(Prev
)
941 /= Generic_Formal_Declarations
(P
);
943 -- Similarly, the generic formals of a generic subprogram are
946 when N_Generic_Subprogram_Declaration
=>
947 if Is_List_Member
(Prev
)
948 and then List_Containing
(Prev
) =
949 Generic_Formal_Declarations
(P
)
956 -- If we reach a subprogram body, entity is not referenceable
957 -- unless it is the defining entity of the body. This will
958 -- happen, e.g. when a function is an attribute renaming that
959 -- is rewritten as a body.
961 when N_Subprogram_Body
=>
962 if Ent
/= Defining_Entity
(P
) then
968 -- If we reach any other body, definitely not referenceable
970 when N_Package_Body |
978 -- For all other cases, keep looking up tree
985 end Publicly_Referenceable
;
987 ---------------------
988 -- Warnings_Off_E1 --
989 ---------------------
991 function Warnings_Off_E1
return Boolean is
993 return Has_Warnings_Off
(E1T
)
994 or else Has_Warnings_Off
(Base_Type
(E1T
))
995 or else Warnings_Off_Check_Spec
(E1
);
998 -- Start of processing for Check_References
1001 -- No messages if warnings are suppressed, or if we have detected any
1002 -- real errors so far (this last check avoids junk messages resulting
1003 -- from errors, e.g. a subunit that is not loaded).
1005 if Warning_Mode
= Suppress
1006 or else Serious_Errors_Detected
/= 0
1011 -- We also skip the messages if any subunits were not loaded (see
1012 -- comment in Sem_Ch10 to understand how this is set, and why it is
1013 -- necessary to suppress the warnings in this case).
1015 if Missing_Subunits
then
1019 -- Otherwise loop through entities, looking for suspicious stuff
1021 E1
:= First_Entity
(E
);
1022 while Present
(E1
) loop
1025 -- We are only interested in source entities. We also don't issue
1026 -- warnings within instances, since the proper place for such
1027 -- warnings is on the template when it is compiled.
1029 if Comes_From_Source
(E1
)
1030 and then Instantiation_Location
(Sloc
(E1
)) = No_Location
1032 -- We are interested in variables and out/in-out parameters, but
1033 -- we exclude protected types, too complicated to worry about.
1035 if Ekind
(E1
) = E_Variable
1037 (Ekind_In
(E1
, E_Out_Parameter
, E_In_Out_Parameter
)
1038 and then not Is_Protected_Type
(Current_Scope
))
1040 -- Case of an unassigned variable
1042 -- First gather any Unset_Reference indication for E1. In the
1043 -- case of a parameter, it is the Spec_Entity that is relevant.
1045 if Ekind
(E1
) = E_Out_Parameter
1046 and then Present
(Spec_Entity
(E1
))
1048 UR
:= Unset_Reference
(Spec_Entity
(E1
));
1050 UR
:= Unset_Reference
(E1
);
1053 -- Special processing for access types
1056 and then Is_Access_Type
(E1T
)
1058 -- For access types, the only time we made a UR entry was
1059 -- for a dereference, and so we post the appropriate warning
1060 -- here (note that the dereference may not be explicit in
1061 -- the source, for example in the case of a dispatching call
1062 -- with an anonymous access controlling formal, or of an
1063 -- assignment of a pointer involving discriminant check on
1064 -- the designated object).
1066 if not Warnings_Off_E1
then
1067 Error_Msg_NE
("??& may be null!", UR
, E1
);
1072 -- Case of variable that could be a constant. Note that we
1073 -- never signal such messages for generic package entities,
1074 -- since a given instance could have modifications outside
1077 elsif Warn_On_Constant
1078 and then (Ekind
(E1
) = E_Variable
1079 and then Has_Initial_Value
(E1
))
1080 and then Never_Set_In_Source_Check_Spec
(E1
)
1081 and then not Address_Taken
(E1
)
1082 and then not Generic_Package_Spec_Entity
(E1
)
1084 -- A special case, if this variable is volatile and not
1085 -- imported, it is not helpful to tell the programmer
1086 -- to mark the variable as constant, since this would be
1087 -- illegal by virtue of RM C.6(13).
1089 if (Is_Volatile
(E1
) or else Has_Volatile_Components
(E1
))
1090 and then not Is_Imported
(E1
)
1093 ("?k?& is not modified, volatile has no effect!", E1
);
1095 -- Another special case, Exception_Occurrence, this catches
1096 -- the case of exception choice (and a bit more too, but not
1097 -- worth doing more investigation here).
1099 elsif Is_RTE
(E1T
, RE_Exception_Occurrence
) then
1102 -- Here we give the warning if referenced and no pragma
1103 -- Unreferenced or Unmodified is present.
1108 if Ekind
(E1
) = E_Variable
then
1109 if Referenced_Check_Spec
(E1
)
1110 and then not Has_Pragma_Unreferenced_Check_Spec
(E1
)
1111 and then not Has_Pragma_Unmodified_Check_Spec
(E1
)
1113 if not Warnings_Off_E1
then
1114 Error_Msg_N
-- CODEFIX
1115 ("?k?& is not modified, "
1116 & "could be declared constant!",
1123 -- Other cases of a variable or parameter never set in source
1125 elsif Never_Set_In_Source_Check_Spec
(E1
)
1127 -- No warning if warning for this case turned off
1129 and then Warn_On_No_Value_Assigned
1131 -- No warning if address taken somewhere
1133 and then not Address_Taken
(E1
)
1135 -- No warning if explicit initial value
1137 and then not Has_Initial_Value
(E1
)
1139 -- No warning for generic package spec entities, since we
1140 -- might set them in a child unit or something like that
1142 and then not Generic_Package_Spec_Entity
(E1
)
1144 -- No warning if fully initialized type, except that for
1145 -- this purpose we do not consider access types to qualify
1146 -- as fully initialized types (relying on an access type
1147 -- variable being null when it is never set is a bit odd).
1149 -- Also we generate warning for an out parameter that is
1150 -- never referenced, since again it seems odd to rely on
1151 -- default initialization to set an out parameter value.
1153 and then (Is_Access_Type
(E1T
)
1154 or else Ekind
(E1
) = E_Out_Parameter
1155 or else not Is_Fully_Initialized_Type
(E1T
))
1157 -- Do not output complaint about never being assigned a
1158 -- value if a pragma Unmodified applies to the variable
1159 -- we are examining, or if it is a parameter, if there is
1160 -- a pragma Unreferenced for the corresponding spec, or
1161 -- if the type is marked as having unreferenced objects.
1162 -- The last is a little peculiar, but better too few than
1163 -- too many warnings in this situation.
1165 if Has_Pragma_Unreferenced_Objects
(E1T
)
1166 or else Has_Pragma_Unmodified_Check_Spec
(E1
)
1170 -- IN OUT parameter case where parameter is referenced. We
1171 -- separate this out, since this is the case where we delay
1172 -- output of the warning until more information is available
1173 -- (about use in an instantiation or address being taken).
1175 elsif Ekind
(E1
) = E_In_Out_Parameter
1176 and then Referenced_Check_Spec
(E1
)
1178 -- Suppress warning if private type, and the procedure
1179 -- has a separate declaration in a different unit. This
1180 -- is the case where the client of a package sees only
1181 -- the private type, and it may be quite reasonable
1182 -- for the logical view to be IN OUT, even if the
1183 -- implementation ends up using access types or some
1184 -- other method to achieve the local effect of a
1185 -- modification. On the other hand if the spec and body
1186 -- are in the same unit, we are in the package body and
1187 -- there we have less excuse for a junk IN OUT parameter.
1189 if Has_Private_Declaration
(E1T
)
1190 and then Present
(Spec_Entity
(E1
))
1191 and then not In_Same_Source_Unit
(E1
, Spec_Entity
(E1
))
1195 -- Suppress warning for any parameter of a dispatching
1196 -- operation, since it is quite reasonable to have an
1197 -- operation that is overridden, and for some subclasses
1198 -- needs the formal to be IN OUT and for others happens
1199 -- not to assign it.
1201 elsif Is_Dispatching_Operation
1202 (Scope
(Goto_Spec_Entity
(E1
)))
1206 -- Suppress warning if composite type contains any access
1207 -- component, since the logical effect of modifying a
1208 -- parameter may be achieved by modifying a referenced
1211 elsif Is_Composite_Type
(E1T
)
1212 and then Has_Access_Values
(E1T
)
1216 -- Suppress warning on formals of an entry body. All
1217 -- references are attached to the formal in the entry
1218 -- declaration, which are marked Is_Entry_Formal.
1220 elsif Ekind
(Scope
(E1
)) = E_Entry
1221 and then not Is_Entry_Formal
(E1
)
1225 -- OK, looks like warning for an IN OUT parameter that
1226 -- could be IN makes sense, but we delay the output of
1227 -- the warning, pending possibly finding out later on
1228 -- that the associated subprogram is used as a generic
1229 -- actual, or its address/access is taken. In these two
1230 -- cases, we suppress the warning because the context may
1231 -- force use of IN OUT, even if in this particular case
1232 -- the formal is not modified.
1235 In_Out_Warnings
.Append
(E1
);
1238 -- Other cases of formals
1240 elsif Is_Formal
(E1
) then
1241 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1242 if Referenced_Check_Spec
(E1
) then
1243 if not Has_Pragma_Unmodified_Check_Spec
(E1
)
1244 and then not Warnings_Off_E1
1246 Output_Reference_Error
1247 ("?f?formal parameter& is read but "
1248 & "never assigned!");
1251 elsif not Has_Pragma_Unreferenced_Check_Spec
(E1
)
1252 and then not Warnings_Off_E1
1254 Output_Reference_Error
1255 ("?f?formal parameter& is not referenced!");
1262 if Referenced
(E1
) then
1263 if not Has_Unmodified
(E1
)
1264 and then not Warnings_Off_E1
1266 Output_Reference_Error
1267 ("?v?variable& is read but never assigned!");
1270 elsif not Has_Unreferenced
(E1
)
1271 and then not Warnings_Off_E1
1273 Output_Reference_Error
-- CODEFIX
1274 ("?v?variable& is never read and never assigned!");
1277 -- Deal with special case where this variable is hidden
1278 -- by a loop variable.
1280 if Ekind
(E1
) = E_Variable
1281 and then Present
(Hiding_Loop_Variable
(E1
))
1282 and then not Warnings_Off_E1
1285 ("?v?for loop implicitly declares loop variable!",
1286 Hiding_Loop_Variable
(E1
));
1288 Error_Msg_Sloc
:= Sloc
(E1
);
1290 ("\?v?declaration hides & declared#!",
1291 Hiding_Loop_Variable
(E1
));
1298 -- Check for unset reference
1300 if Warn_On_No_Value_Assigned
and then Present
(UR
) then
1302 -- For other than access type, go back to original node to
1303 -- deal with case where original unset reference has been
1304 -- rewritten during expansion.
1306 -- In some cases, the original node may be a type conversion
1307 -- or qualification, and in this case we want the object
1310 UR
:= Original_Node
(UR
);
1311 while Nkind
(UR
) = N_Type_Conversion
1312 or else Nkind
(UR
) = N_Qualified_Expression
1313 or else Nkind
(UR
) = N_Expression_With_Actions
1315 UR
:= Expression
(UR
);
1318 -- Don't issue warning if appearing inside Initial_Condition
1319 -- pragma or aspect, since that expression is not evaluated
1320 -- at the point where it occurs in the source.
1322 if In_Pragma_Expression
(UR
, Name_Initial_Condition
) then
1326 -- Here we issue the warning, all checks completed
1328 -- If we have a return statement, this was a case of an OUT
1329 -- parameter not being set at the time of the return. (Note:
1330 -- it can't be N_Extended_Return_Statement, because those
1331 -- are only for functions, and functions do not allow OUT
1334 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1335 if Nkind
(UR
) = N_Simple_Return_Statement
1336 and then not Has_Pragma_Unmodified_Check_Spec
(E1
)
1338 if not Warnings_Off_E1
then
1340 ("?v?OUT parameter& not set before return",
1344 -- If the unset reference is a selected component
1345 -- prefix from source, mention the component as well.
1346 -- If the selected component comes from expansion, all
1347 -- we know is that the entity is not fully initialized
1348 -- at the point of the reference. Locate a random
1349 -- uninitialized component to get a better message.
1351 elsif Nkind
(Parent
(UR
)) = N_Selected_Component
then
1352 Error_Msg_Node_2
:= Selector_Name
(Parent
(UR
));
1354 if not Comes_From_Source
(Parent
(UR
)) then
1359 Comp
:= First_Entity
(E1T
);
1360 while Present
(Comp
) loop
1361 if Ekind
(Comp
) = E_Component
1362 and then Nkind
(Parent
(Comp
)) =
1363 N_Component_Declaration
1364 and then No
(Expression
(Parent
(Comp
)))
1366 Error_Msg_Node_2
:= Comp
;
1375 -- Issue proper warning. This is a case of referencing
1376 -- a variable before it has been explicitly assigned.
1377 -- For access types, UR was only set for dereferences,
1378 -- so the issue is that the value may be null.
1380 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1381 if not Warnings_Off_E1
then
1382 if Is_Access_Type
(Etype
(Parent
(UR
))) then
1383 Error_Msg_N
("?`&.&` may be null!", UR
);
1386 ("?`&.&` may be referenced before "
1387 & "it has a value!", UR
);
1391 -- All other cases of unset reference active
1393 elsif not Warnings_Off_E1
then
1395 ("?& may be referenced before it has a value!",
1404 -- Then check for unreferenced entities. Note that we are only
1405 -- interested in entities whose Referenced flag is not set.
1407 if not Referenced_Check_Spec
(E1
)
1409 -- If Referenced_As_LHS is set, then that's still interesting
1410 -- (potential "assigned but never read" case), but not if we
1411 -- have pragma Unreferenced, which cancels this warning.
1413 and then (not Referenced_As_LHS_Check_Spec
(E1
)
1414 or else not Has_Unreferenced
(E1
))
1416 -- Check that warnings on unreferenced entities are enabled
1419 ((Check_Unreferenced
and then not Is_Formal
(E1
))
1421 -- Case of warning on unreferenced formal
1424 (Check_Unreferenced_Formals
and then Is_Formal
(E1
))
1426 -- Case of warning on unread variables modified by an
1427 -- assignment, or an OUT parameter if it is the only one.
1430 (Warn_On_Modified_Unread
1431 and then Referenced_As_LHS_Check_Spec
(E1
))
1433 -- Case of warning on any unread OUT parameter (note
1434 -- such indications are only set if the appropriate
1435 -- warning options were set, so no need to recheck here.)
1438 Referenced_As_Out_Parameter_Check_Spec
(E1
))
1440 -- All other entities, including local packages that cannot be
1441 -- referenced from elsewhere, including those declared within a
1444 and then (Is_Object
(E1
)
1448 Ekind
(E1
) = E_Label
1450 Ekind
(E1
) = E_Exception
1452 Ekind
(E1
) = E_Named_Integer
1454 Ekind
(E1
) = E_Named_Real
1456 Is_Overloadable
(E1
)
1458 -- Package case, if the main unit is a package spec
1459 -- or generic package spec, then there may be a
1460 -- corresponding body that references this package
1461 -- in some other file. Otherwise we can be sure
1462 -- that there is no other reference.
1465 (Ekind
(E1
) = E_Package
1467 not Is_Package_Or_Generic_Package
1468 (Cunit_Entity
(Current_Sem_Unit
))))
1470 -- Exclude instantiations, since there is no reason why every
1471 -- entity in an instantiation should be referenced.
1473 and then Instantiation_Location
(Sloc
(E1
)) = No_Location
1475 -- Exclude formal parameters from bodies if the corresponding
1476 -- spec entity has been referenced in the case where there is
1479 and then not (Is_Formal
(E1
)
1480 and then Ekind
(Scope
(E1
)) = E_Subprogram_Body
1481 and then Present
(Spec_Entity
(E1
))
1482 and then Referenced
(Spec_Entity
(E1
)))
1484 -- Consider private type referenced if full view is referenced.
1485 -- If there is not full view, this is a generic type on which
1486 -- warnings are also useful.
1489 not (Is_Private_Type
(E1
)
1490 and then Present
(Full_View
(E1
))
1491 and then Referenced
(Full_View
(E1
)))
1493 -- Don't worry about full view, only about private type
1495 and then not Has_Private_Declaration
(E1
)
1497 -- Eliminate dispatching operations from consideration, we
1498 -- cannot tell if these are referenced or not in any easy
1499 -- manner (note this also catches Adjust/Finalize/Initialize).
1501 and then not Is_Dispatching_Operation
(E1
)
1503 -- Check entity that can be publicly referenced (we do not give
1504 -- messages for such entities, since there could be other
1505 -- units, not involved in this compilation, that contain
1506 -- relevant references.
1508 and then not Publicly_Referenceable
(E1
)
1510 -- Class wide types are marked as source entities, but they are
1511 -- not really source entities, and are always created, so we do
1512 -- not care if they are not referenced.
1514 and then Ekind
(E1
) /= E_Class_Wide_Type
1516 -- Objects other than parameters of task types are allowed to
1517 -- be non-referenced, since they start up tasks.
1519 and then ((Ekind
(E1
) /= E_Variable
1520 and then Ekind
(E1
) /= E_Constant
1521 and then Ekind
(E1
) /= E_Component
)
1522 or else not Is_Task_Type
(E1T
))
1524 -- For subunits, only place warnings on the main unit itself,
1525 -- since parent units are not completely compiled.
1527 and then (Nkind
(Unit
(Cunit
(Main_Unit
))) /= N_Subunit
1528 or else Get_Source_Unit
(E1
) = Main_Unit
)
1530 -- No warning on a return object, because these are often
1531 -- created with a single expression and an implicit return.
1532 -- If the object is a variable there will be a warning
1533 -- indicating that it could be declared constant.
1536 (Ekind
(E1
) = E_Constant
and then Is_Return_Object
(E1
))
1538 -- Suppress warnings in internal units if not in -gnatg mode
1539 -- (these would be junk warnings for an applications program,
1540 -- since they refer to problems in internal units).
1543 or else not Is_Internal_File_Name
1544 (Unit_File_Name
(Get_Source_Unit
(E1
)))
1546 -- We do not immediately flag the error. This is because we
1547 -- have not expanded generic bodies yet, and they may have
1548 -- the missing reference. So instead we park the entity on a
1549 -- list, for later processing. However for the case of an
1550 -- accept statement we want to output messages now, since
1551 -- we know we already have all information at hand, and we
1552 -- also want to have separate warnings for each accept
1553 -- statement for the same entry.
1555 if Present
(Anod
) then
1556 pragma Assert
(Is_Formal
(E1
));
1558 -- The unreferenced entity is E1, but post the warning
1559 -- on the body entity for this accept statement.
1561 if not Warnings_Off_E1
then
1562 Warn_On_Unreferenced_Entity
1563 (E1
, Body_Formal
(E1
, Accept_Statement
=> Anod
));
1566 elsif not Warnings_Off_E1
then
1567 Unreferenced_Entities
.Append
(E1
);
1571 -- Generic units are referenced in the generic body, but if they
1572 -- are not public and never instantiated we want to force a
1573 -- warning on them. We treat them as redundant constructs to
1576 elsif Is_Generic_Subprogram
(E1
)
1577 and then not Is_Instantiated
(E1
)
1578 and then not Publicly_Referenceable
(E1
)
1579 and then Instantiation_Depth
(Sloc
(E1
)) = 0
1580 and then Warn_On_Redundant_Constructs
1582 if not Warnings_Off_E1
then
1583 Unreferenced_Entities
.Append
(E1
);
1585 -- Force warning on entity
1587 Set_Referenced
(E1
, False);
1592 -- Recurse into nested package or block. Do not recurse into a formal
1593 -- package, because the corresponding body is not analyzed.
1596 if (Is_Package_Or_Generic_Package
(E1
)
1597 and then Nkind
(Parent
(E1
)) = N_Package_Specification
1599 Nkind
(Original_Node
(Unit_Declaration_Node
(E1
)))
1600 /= N_Formal_Package_Declaration
)
1602 or else Ekind
(E1
) = E_Block
1604 Check_References
(E1
);
1609 end Check_References
;
1611 ---------------------------
1612 -- Check_Unset_Reference --
1613 ---------------------------
1615 procedure Check_Unset_Reference
(N
: Node_Id
) is
1616 Typ
: constant Entity_Id
:= Etype
(N
);
1618 function Is_OK_Fully_Initialized
return Boolean;
1619 -- This function returns true if the given node N is fully initialized
1620 -- so that the reference is safe as far as this routine is concerned.
1621 -- Safe generally means that the type of N is a fully initialized type.
1622 -- The one special case is that for access types, which are always fully
1623 -- initialized, we don't consider a dereference OK since it will surely
1624 -- be dereferencing a null value, which won't do.
1626 function Prefix_Has_Dereference
(Pref
: Node_Id
) return Boolean;
1627 -- Used to test indexed or selected component or slice to see if the
1628 -- evaluation of the prefix depends on a dereference, and if so, returns
1629 -- True, in which case we always check the prefix, even if we know that
1630 -- the referenced component is initialized. Pref is the prefix to test.
1632 -----------------------------
1633 -- Is_OK_Fully_Initialized --
1634 -----------------------------
1636 function Is_OK_Fully_Initialized
return Boolean is
1638 if Is_Access_Type
(Typ
) and then Is_Dereferenced
(N
) then
1641 return Is_Fully_Initialized_Type
(Typ
);
1643 end Is_OK_Fully_Initialized
;
1645 ----------------------------
1646 -- Prefix_Has_Dereference --
1647 ----------------------------
1649 function Prefix_Has_Dereference
(Pref
: Node_Id
) return Boolean is
1651 -- If prefix is of an access type, it certainly needs a dereference
1653 if Is_Access_Type
(Etype
(Pref
)) then
1656 -- If prefix is explicit dereference, that's a dereference for sure
1658 elsif Nkind
(Pref
) = N_Explicit_Dereference
then
1661 -- If prefix is itself a component reference or slice check prefix
1663 elsif Nkind
(Pref
) = N_Slice
1664 or else Nkind
(Pref
) = N_Indexed_Component
1665 or else Nkind
(Pref
) = N_Selected_Component
1667 return Prefix_Has_Dereference
(Prefix
(Pref
));
1669 -- All other cases do not involve a dereference
1674 end Prefix_Has_Dereference
;
1676 -- Start of processing for Check_Unset_Reference
1679 -- Nothing to do if warnings suppressed
1681 if Warning_Mode
= Suppress
then
1685 -- Nothing to do for numeric or string literal. Do this test early to
1686 -- save time in a common case (it does not matter that we do not include
1687 -- character literal here, since that will be caught later on in the
1688 -- when others branch of the case statement).
1690 if Nkind
(N
) in N_Numeric_Or_String_Literal
then
1694 -- Ignore reference unless it comes from source. Almost always if we
1695 -- have a reference from generated code, it is bogus (e.g. calls to init
1696 -- procs to set default discriminant values).
1698 if not Comes_From_Source
(N
) then
1702 -- Otherwise see what kind of node we have. If the entity already has an
1703 -- unset reference, it is not necessarily the earliest in the text,
1704 -- because resolution of the prefix of selected components is completed
1705 -- before the resolution of the selected component itself. As a result,
1706 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1707 -- in right-to-left order. If there is already an unset reference, we
1708 -- check whether N is earlier before proceeding.
1712 -- For identifier or expanded name, examine the entity involved
1714 when N_Identifier | N_Expanded_Name
=>
1716 E
: constant Entity_Id
:= Entity
(N
);
1719 if (Ekind
(E
) = E_Variable
1721 Ekind
(E
) = E_Out_Parameter
)
1722 and then Never_Set_In_Source_Check_Spec
(E
)
1723 and then not Has_Initial_Value
(E
)
1724 and then (No
(Unset_Reference
(E
))
1726 Earlier_In_Extended_Unit
1727 (Sloc
(N
), Sloc
(Unset_Reference
(E
))))
1728 and then not Has_Pragma_Unmodified_Check_Spec
(E
)
1729 and then not Warnings_Off_Check_Spec
(E
)
1731 -- We may have an unset reference. The first test is whether
1732 -- this is an access to a discriminant of a record or a
1733 -- component with default initialization. Both of these
1734 -- cases can be ignored, since the actual object that is
1735 -- referenced is definitely initialized. Note that this
1736 -- covers the case of reading discriminants of an OUT
1737 -- parameter, which is OK even in Ada 83.
1739 -- Note that we are only interested in a direct reference to
1740 -- a record component here. If the reference is through an
1741 -- access type, then the access object is being referenced,
1742 -- not the record, and still deserves an unset reference.
1744 if Nkind
(Parent
(N
)) = N_Selected_Component
1745 and not Is_Access_Type
(Typ
)
1748 ES
: constant Entity_Id
:=
1749 Entity
(Selector_Name
(Parent
(N
)));
1751 if Ekind
(ES
) = E_Discriminant
1753 (Present
(Declaration_Node
(ES
))
1755 Present
(Expression
(Declaration_Node
(ES
))))
1762 -- Exclude fully initialized types
1764 if Is_OK_Fully_Initialized
then
1768 -- Here we have a potential unset reference. But before we
1769 -- get worried about it, we have to make sure that the
1770 -- entity declaration is in the same procedure as the
1771 -- reference, since if they are in separate procedures, then
1772 -- we have no idea about sequential execution.
1774 -- The tests in the loop below catch all such cases, but do
1775 -- allow the reference to appear in a loop, block, or
1776 -- package spec that is nested within the declaring scope.
1777 -- As always, it is possible to construct cases where the
1778 -- warning is wrong, that is why it is a warning.
1780 Potential_Unset_Reference
: declare
1782 SE
: constant Entity_Id
:= Scope
(E
);
1784 function Within_Postcondition
return Boolean;
1785 -- Returns True iff N is within a Postcondition, an
1786 -- Ensures component in a Test_Case, or a Contract_Cases.
1788 --------------------------
1789 -- Within_Postcondition --
1790 --------------------------
1792 function Within_Postcondition
return Boolean is
1797 while Present
(Nod
) loop
1798 if Nkind
(Nod
) = N_Pragma
1799 and then Nam_In
(Pragma_Name
(Nod
),
1801 Name_Contract_Cases
)
1805 elsif Present
(Parent
(Nod
)) then
1808 if Nkind
(P
) = N_Pragma
1810 Pragma_Name
(P
) = Name_Test_Case
1812 Nod
= Get_Ensures_From_CTC_Pragma
(P
)
1818 Nod
:= Parent
(Nod
);
1822 end Within_Postcondition
;
1824 -- Start of processing for Potential_Unset_Reference
1827 SR
:= Current_Scope
;
1829 if SR
= Standard_Standard
1830 or else Is_Subprogram
(SR
)
1831 or else Is_Concurrent_Body
(SR
)
1832 or else Is_Concurrent_Type
(SR
)
1840 -- Case of reference has an access type. This is a
1841 -- special case since access types are always set to null
1842 -- so cannot be truly uninitialized, but we still want to
1843 -- warn about cases of obvious null dereference.
1845 if Is_Access_Type
(Typ
) then
1846 Access_Type_Case
: declare
1850 (N
: Node_Id
) return Traverse_Result
;
1851 -- Process function for instantiation of Traverse
1852 -- below. Checks if N contains reference to E other
1853 -- than a dereference.
1855 function Ref_In
(Nod
: Node_Id
) return Boolean;
1856 -- Determines whether Nod contains a reference to
1857 -- the entity E that is not a dereference.
1864 (N
: Node_Id
) return Traverse_Result
1867 if Is_Entity_Name
(N
)
1868 and then Entity
(N
) = E
1869 and then not Is_Dereferenced
(N
)
1881 function Ref_In
(Nod
: Node_Id
) return Boolean is
1882 function Traverse
is new Traverse_Func
(Process
);
1884 return Traverse
(Nod
) = Abandon
;
1887 -- Start of processing for Access_Type_Case
1890 -- Don't bother if we are inside an instance, since
1891 -- the compilation of the generic template is where
1892 -- the warning should be issued.
1898 -- Don't bother if this is not the main unit. If we
1899 -- try to give this warning for with'ed units, we
1900 -- get some false positives, since we do not record
1901 -- references in other units.
1903 if not In_Extended_Main_Source_Unit
(E
)
1905 not In_Extended_Main_Source_Unit
(N
)
1910 -- We are only interested in dereferences
1912 if not Is_Dereferenced
(N
) then
1916 -- One more check, don't bother with references
1917 -- that are inside conditional statements or WHILE
1918 -- loops if the condition references the entity in
1919 -- question. This avoids most false positives.
1926 if (Nkind
(P
) = N_If_Statement
1928 Nkind
(P
) = N_Elsif_Part
)
1929 and then Ref_In
(Condition
(P
))
1933 elsif Nkind
(P
) = N_Loop_Statement
1934 and then Present
(Iteration_Scheme
(P
))
1936 Ref_In
(Condition
(Iteration_Scheme
(P
)))
1941 end Access_Type_Case
;
1944 -- One more check, don't bother if we are within a
1945 -- postcondition, since the expression occurs in a
1946 -- place unrelated to the actual test.
1948 if not Within_Postcondition
then
1950 -- Here we definitely have a case for giving a warning
1951 -- for a reference to an unset value. But we don't
1952 -- give the warning now. Instead set Unset_Reference
1953 -- in the identifier involved. The reason for this is
1954 -- that if we find the variable is never ever assigned
1955 -- a value then that warning is more important and
1956 -- there is no point in giving the reference warning.
1958 -- If this is an identifier, set the field directly
1960 if Nkind
(N
) = N_Identifier
then
1961 Set_Unset_Reference
(E
, N
);
1963 -- Otherwise it is an expanded name, so set the field
1964 -- of the actual identifier for the reference.
1967 Set_Unset_Reference
(E
, Selector_Name
(N
));
1970 end Potential_Unset_Reference
;
1974 -- Indexed component or slice
1976 when N_Indexed_Component | N_Slice
=>
1978 -- If prefix does not involve dereferencing an access type, then
1979 -- we know we are OK if the component type is fully initialized,
1980 -- since the component will have been set as part of the default
1983 if not Prefix_Has_Dereference
(Prefix
(N
))
1984 and then Is_OK_Fully_Initialized
1988 -- Look at prefix in access type case, or if the component is not
1989 -- fully initialized.
1992 Check_Unset_Reference
(Prefix
(N
));
1997 when N_Selected_Component
=>
1999 Pref
: constant Node_Id
:= Prefix
(N
);
2000 Ent
: constant Entity_Id
:= Entity
(Selector_Name
(N
));
2003 -- If prefix involves dereferencing an access type, always
2004 -- check the prefix, since the issue then is whether this
2005 -- access value is null.
2007 if Prefix_Has_Dereference
(Pref
) then
2010 -- Always go to prefix if no selector entity is set. Can this
2011 -- happen in the normal case? Not clear, but it definitely can
2012 -- happen in error cases.
2017 -- For a record component, check some cases where we have
2018 -- reasonable cause to consider that the component is known to
2019 -- be or probably is initialized. In this case, we don't care
2020 -- if the prefix itself was explicitly initialized.
2022 -- Discriminants are always considered initialized
2024 elsif Ekind
(Ent
) = E_Discriminant
then
2027 -- An explicitly initialized component is certainly initialized
2029 elsif Nkind
(Parent
(Ent
)) = N_Component_Declaration
2030 and then Present
(Expression
(Parent
(Ent
)))
2034 -- A fully initialized component is initialized
2036 elsif Is_OK_Fully_Initialized
then
2040 -- If none of those cases apply, check the record type prefix
2042 Check_Unset_Reference
(Pref
);
2045 -- For type conversions, qualifications, or expressions with actions,
2046 -- examine the expression.
2048 when N_Type_Conversion |
2049 N_Qualified_Expression |
2050 N_Expression_With_Actions
=>
2051 Check_Unset_Reference
(Expression
(N
));
2053 -- For explicit dereference, always check prefix, which will generate
2054 -- an unset reference (since this is a case of dereferencing null).
2056 when N_Explicit_Dereference
=>
2057 Check_Unset_Reference
(Prefix
(N
));
2059 -- All other cases are not cases of an unset reference
2065 end Check_Unset_Reference
;
2067 ------------------------
2068 -- Check_Unused_Withs --
2069 ------------------------
2071 procedure Check_Unused_Withs
(Spec_Unit
: Unit_Number_Type
:= No_Unit
) is
2077 Munite
: constant Entity_Id
:= Cunit_Entity
(Main_Unit
);
2078 -- This is needed for checking the special renaming case
2080 procedure Check_One_Unit
(Unit
: Unit_Number_Type
);
2081 -- Subsidiary procedure, performs checks for specified unit
2083 --------------------
2084 -- Check_One_Unit --
2085 --------------------
2087 procedure Check_One_Unit
(Unit
: Unit_Number_Type
) is
2088 Is_Visible_Renaming
: Boolean := False;
2091 procedure Check_Inner_Package
(Pack
: Entity_Id
);
2092 -- Pack is a package local to a unit in a with_clause. Both the unit
2093 -- and Pack are referenced. If none of the entities in Pack are
2094 -- referenced, then the only occurrence of Pack is in a USE clause
2095 -- or a pragma, and a warning is worthwhile as well.
2097 function Check_System_Aux
return Boolean;
2098 -- Before giving a warning on a with_clause for System, check whether
2099 -- a system extension is present.
2101 function Find_Package_Renaming
2103 L
: Entity_Id
) return Entity_Id
;
2104 -- The only reference to a context unit may be in a renaming
2105 -- declaration. If this renaming declares a visible entity, do not
2106 -- warn that the context clause could be moved to the body, because
2107 -- the renaming may be intended to re-export the unit.
2109 function Has_Visible_Entities
(P
: Entity_Id
) return Boolean;
2110 -- This function determines if a package has any visible entities.
2111 -- True is returned if there is at least one declared visible entity,
2112 -- otherwise False is returned (e.g. case of only pragmas present).
2114 -------------------------
2115 -- Check_Inner_Package --
2116 -------------------------
2118 procedure Check_Inner_Package
(Pack
: Entity_Id
) is
2120 Un
: constant Node_Id
:= Sinfo
.Unit
(Cnode
);
2122 function Check_Use_Clause
(N
: Node_Id
) return Traverse_Result
;
2123 -- If N is a use_clause for Pack, emit warning
2125 procedure Check_Use_Clauses
is new
2126 Traverse_Proc
(Check_Use_Clause
);
2128 ----------------------
2129 -- Check_Use_Clause --
2130 ----------------------
2132 function Check_Use_Clause
(N
: Node_Id
) return Traverse_Result
is
2136 if Nkind
(N
) = N_Use_Package_Clause
then
2137 Nam
:= First
(Names
(N
));
2138 while Present
(Nam
) loop
2139 if Entity
(Nam
) = Pack
then
2141 -- Suppress message if any serious errors detected
2142 -- that turn off expansion, and thus result in false
2143 -- positives for this warning.
2145 if Serious_Errors_Detected
= 0 then
2146 Error_Msg_Qual_Level
:= 1;
2147 Error_Msg_NE
-- CODEFIX
2148 ("?u?no entities of package& are referenced!",
2150 Error_Msg_Qual_Level
:= 0;
2159 end Check_Use_Clause
;
2161 -- Start of processing for Check_Inner_Package
2164 E
:= First_Entity
(Pack
);
2165 while Present
(E
) loop
2166 if Referenced_Check_Spec
(E
) then
2173 -- No entities of the package are referenced. Check whether the
2174 -- reference to the package itself is a use clause, and if so
2175 -- place a warning on it.
2177 Check_Use_Clauses
(Un
);
2178 end Check_Inner_Package
;
2180 ----------------------
2181 -- Check_System_Aux --
2182 ----------------------
2184 function Check_System_Aux
return Boolean is
2188 if Chars
(Lunit
) = Name_System
2189 and then Scope
(Lunit
) = Standard_Standard
2190 and then Present_System_Aux
2192 Ent
:= First_Entity
(System_Aux_Id
);
2193 while Present
(Ent
) loop
2194 if Referenced_Check_Spec
(Ent
) then
2203 end Check_System_Aux
;
2205 ---------------------------
2206 -- Find_Package_Renaming --
2207 ---------------------------
2209 function Find_Package_Renaming
2211 L
: Entity_Id
) return Entity_Id
2217 Is_Visible_Renaming
:= False;
2219 E1
:= First_Entity
(P
);
2220 while Present
(E1
) loop
2221 if Ekind
(E1
) = E_Package
2222 and then Renamed_Object
(E1
) = L
2224 Is_Visible_Renaming
:= not Is_Hidden
(E1
);
2227 elsif Ekind
(E1
) = E_Package
2228 and then No
(Renamed_Object
(E1
))
2229 and then not Is_Generic_Instance
(E1
)
2231 R
:= Find_Package_Renaming
(E1
, L
);
2234 Is_Visible_Renaming
:= not Is_Hidden
(R
);
2243 end Find_Package_Renaming
;
2245 --------------------------
2246 -- Has_Visible_Entities --
2247 --------------------------
2249 function Has_Visible_Entities
(P
: Entity_Id
) return Boolean is
2253 -- If unit in context is not a package, it is a subprogram that
2254 -- is not called or a generic unit that is not instantiated
2255 -- in the current unit, and warning is appropriate.
2257 if Ekind
(P
) /= E_Package
then
2261 -- If unit comes from a limited_with clause, look for declaration
2262 -- of shadow entities.
2264 if Present
(Limited_View
(P
)) then
2265 E
:= First_Entity
(Limited_View
(P
));
2267 E
:= First_Entity
(P
);
2271 and then E
/= First_Private_Entity
(P
)
2273 if Comes_From_Source
(E
)
2274 or else Present
(Limited_View
(P
))
2283 end Has_Visible_Entities
;
2285 -- Start of processing for Check_One_Unit
2288 Cnode
:= Cunit
(Unit
);
2290 -- Only do check in units that are part of the extended main unit.
2291 -- This is actually a necessary restriction, because in the case of
2292 -- subprogram acting as its own specification, there can be with's in
2293 -- subunits that we will not see.
2295 if not In_Extended_Main_Source_Unit
(Cnode
) then
2298 -- In configurable run time mode, we remove the bodies of non-inlined
2299 -- subprograms, which may lead to spurious warnings, which are
2300 -- clearly undesirable.
2302 elsif Configurable_Run_Time_Mode
2303 and then Is_Predefined_File_Name
(Unit_File_Name
(Unit
))
2308 -- Loop through context items in this unit
2310 Item
:= First
(Context_Items
(Cnode
));
2311 while Present
(Item
) loop
2312 if Nkind
(Item
) = N_With_Clause
2313 and then not Implicit_With
(Item
)
2314 and then In_Extended_Main_Source_Unit
(Item
)
2316 Lunit
:= Entity
(Name
(Item
));
2318 -- Check if this unit is referenced (skip the check if this
2319 -- is explicitly marked by a pragma Unreferenced).
2321 if not Referenced
(Lunit
)
2322 and then not Has_Unreferenced
(Lunit
)
2324 -- Suppress warnings in internal units if not in -gnatg mode
2325 -- (these would be junk warnings for an application program,
2326 -- since they refer to problems in internal units).
2329 or else not Is_Internal_File_Name
(Unit_File_Name
(Unit
))
2331 -- Here we definitely have a non-referenced unit. If it
2332 -- is the special call for a spec unit, then just set the
2333 -- flag to be read later.
2335 if Unit
= Spec_Unit
then
2336 Set_Unreferenced_In_Spec
(Item
);
2338 -- Otherwise simple unreferenced message, but skip this
2339 -- if no visible entities, because that is most likely a
2340 -- case where warning would be false positive (e.g. a
2341 -- package with only a linker options pragma and nothing
2342 -- else or a pragma elaborate with a body library task).
2344 elsif Has_Visible_Entities
(Entity
(Name
(Item
))) then
2345 Error_Msg_N
-- CODEFIX
2346 ("?u?unit& is not referenced!", Name
(Item
));
2350 -- If main unit is a renaming of this unit, then we consider
2351 -- the with to be OK (obviously it is needed in this case).
2352 -- This may be transitive: the unit in the with_clause may
2353 -- itself be a renaming, in which case both it and the main
2354 -- unit rename the same ultimate package.
2356 elsif Present
(Renamed_Entity
(Munite
))
2358 (Renamed_Entity
(Munite
) = Lunit
2359 or else Renamed_Entity
(Munite
) = Renamed_Entity
(Lunit
))
2363 -- If this unit is referenced, and it is a package, we do
2364 -- another test, to see if any of the entities in the package
2365 -- are referenced. If none of the entities are referenced, we
2366 -- still post a warning. This occurs if the only use of the
2367 -- package is in a use clause, or in a package renaming
2368 -- declaration. This check is skipped for packages that are
2369 -- renamed in a spec, since the entities in such a package are
2370 -- visible to clients via the renaming.
2372 elsif Ekind
(Lunit
) = E_Package
2373 and then not Renamed_In_Spec
(Lunit
)
2375 -- If Is_Instantiated is set, it means that the package is
2376 -- implicitly instantiated (this is the case of parent
2377 -- instance or an actual for a generic package formal), and
2378 -- this counts as a reference.
2380 if Is_Instantiated
(Lunit
) then
2383 -- If no entities in package, and there is a pragma
2384 -- Elaborate_Body present, then assume that this with is
2385 -- done for purposes of this elaboration.
2387 elsif No
(First_Entity
(Lunit
))
2388 and then Has_Pragma_Elaborate_Body
(Lunit
)
2392 -- Otherwise see if any entities have been referenced
2395 if Limited_Present
(Item
) then
2396 Ent
:= First_Entity
(Limited_View
(Lunit
));
2398 Ent
:= First_Entity
(Lunit
);
2402 -- No more entities, and we did not find one that was
2403 -- referenced. Means we have a definite case of a with
2404 -- none of whose entities was referenced.
2408 -- If in spec, just set the flag
2410 if Unit
= Spec_Unit
then
2411 Set_No_Entities_Ref_In_Spec
(Item
);
2413 elsif Check_System_Aux
then
2416 -- Else give the warning
2419 -- Warn if we unreferenced flag set and we have
2420 -- not had serious errors. The reason we inhibit
2421 -- the message if there are errors is to prevent
2422 -- false positives from disabling expansion.
2424 if not Has_Unreferenced
(Entity
(Name
(Item
)))
2425 and then Serious_Errors_Detected
= 0
2427 Error_Msg_N
-- CODEFIX
2428 ("?u?no entities of & are referenced!",
2432 -- Look for renamings of this package, and flag
2433 -- them as well. If the original package has
2434 -- warnings off, we suppress the warning on the
2435 -- renaming as well.
2437 Pack
:= Find_Package_Renaming
(Munite
, Lunit
);
2440 and then not Has_Warnings_Off
(Lunit
)
2441 and then not Has_Unreferenced
(Pack
)
2443 Error_Msg_NE
-- CODEFIX
2444 ("?u?no entities of & are referenced!",
2445 Unit_Declaration_Node
(Pack
),
2452 -- Case of entity being referenced. The reference may
2453 -- come from a limited_with_clause, in which case the
2454 -- limited view of the entity carries the flag.
2456 elsif Referenced_Check_Spec
(Ent
)
2457 or else Referenced_As_LHS_Check_Spec
(Ent
)
2458 or else Referenced_As_Out_Parameter_Check_Spec
(Ent
)
2460 (From_Limited_With
(Ent
)
2461 and then Is_Incomplete_Type
(Ent
)
2462 and then Present
(Non_Limited_View
(Ent
))
2463 and then Referenced
(Non_Limited_View
(Ent
)))
2465 -- This means that the with is indeed fine, in that
2466 -- it is definitely needed somewhere, and we can
2467 -- quit worrying about this one...
2469 -- Except for one little detail: if either of the
2470 -- flags was set during spec processing, this is
2471 -- where we complain that the with could be moved
2472 -- from the spec. If the spec contains a visible
2473 -- renaming of the package, inhibit warning to move
2474 -- with_clause to body.
2476 if Ekind
(Munite
) = E_Package_Body
then
2478 Find_Package_Renaming
2479 (Spec_Entity
(Munite
), Lunit
);
2484 -- If a renaming is present in the spec do not warn
2485 -- because the body or child unit may depend on it.
2488 and then Renamed_Entity
(Pack
) = Lunit
2492 elsif Unreferenced_In_Spec
(Item
) then
2493 Error_Msg_N
-- CODEFIX
2494 ("?u?unit& is not referenced in spec!",
2497 elsif No_Entities_Ref_In_Spec
(Item
) then
2498 Error_Msg_N
-- CODEFIX
2499 ("?u?no entities of & are referenced in spec!",
2503 if Ekind
(Ent
) = E_Package
then
2504 Check_Inner_Package
(Ent
);
2510 if not Is_Visible_Renaming
then
2511 Error_Msg_N
-- CODEFIX
2512 ("\?u?with clause might be moved to body!",
2518 -- Move to next entity to continue search
2526 -- For a generic package, the only interesting kind of
2527 -- reference is an instantiation, since entities cannot be
2528 -- referenced directly.
2530 elsif Is_Generic_Unit
(Lunit
) then
2532 -- Unit was never instantiated, set flag for case of spec
2533 -- call, or give warning for normal call.
2535 if not Is_Instantiated
(Lunit
) then
2536 if Unit
= Spec_Unit
then
2537 Set_Unreferenced_In_Spec
(Item
);
2539 Error_Msg_N
-- CODEFIX
2540 ("?u?unit& is never instantiated!", Name
(Item
));
2543 -- If unit was indeed instantiated, make sure that flag is
2544 -- not set showing it was uninstantiated in the spec, and if
2545 -- so, give warning.
2547 elsif Unreferenced_In_Spec
(Item
) then
2549 ("?u?unit& is not instantiated in spec!", Name
(Item
));
2550 Error_Msg_N
-- CODEFIX
2551 ("\?u?with clause can be moved to body!", Name
(Item
));
2560 -- Start of processing for Check_Unused_Withs
2563 -- Immediate return if no semantics or warning flag not set
2565 if not Opt
.Check_Withs
or else Operating_Mode
= Check_Syntax
then
2569 -- Flag any unused with clauses. For a subunit, check only the units
2570 -- in its context, not those of the parent, which may be needed by other
2571 -- subunits. We will get the full warnings when we compile the parent,
2572 -- but the following is helpful when compiling a subunit by itself.
2574 if Nkind
(Unit
(Cunit
(Main_Unit
))) = N_Subunit
then
2575 if Current_Sem_Unit
= Main_Unit
then
2576 Check_One_Unit
(Main_Unit
);
2582 -- Process specified units
2584 if Spec_Unit
= No_Unit
then
2586 -- For main call, check all units
2588 for Unit
in Main_Unit
.. Last_Unit
loop
2589 Check_One_Unit
(Unit
);
2593 -- For call for spec, check only the spec
2595 Check_One_Unit
(Spec_Unit
);
2597 end Check_Unused_Withs
;
2599 ---------------------------------
2600 -- Generic_Package_Spec_Entity --
2601 ---------------------------------
2603 function Generic_Package_Spec_Entity
(E
: Entity_Id
) return Boolean is
2607 if Is_Package_Body_Entity
(E
) then
2613 if S
= Standard_Standard
then
2616 elsif Ekind
(S
) = E_Generic_Package
then
2619 elsif Ekind
(S
) = E_Package
then
2627 end Generic_Package_Spec_Entity
;
2629 ----------------------
2630 -- Goto_Spec_Entity --
2631 ----------------------
2633 function Goto_Spec_Entity
(E
: Entity_Id
) return Entity_Id
is
2636 and then Present
(Spec_Entity
(E
))
2638 return Spec_Entity
(E
);
2642 end Goto_Spec_Entity
;
2644 --------------------------------------
2645 -- Has_Pragma_Unmodified_Check_Spec --
2646 --------------------------------------
2648 function Has_Pragma_Unmodified_Check_Spec
2649 (E
: Entity_Id
) return Boolean
2652 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2654 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2655 -- to mess with Unmodified flags on both body and spec entities.
2657 return Has_Unmodified
(E
)
2659 Has_Unmodified
(Spec_Entity
(E
));
2662 return Has_Unmodified
(E
);
2664 end Has_Pragma_Unmodified_Check_Spec
;
2666 ----------------------------------------
2667 -- Has_Pragma_Unreferenced_Check_Spec --
2668 ----------------------------------------
2670 function Has_Pragma_Unreferenced_Check_Spec
2671 (E
: Entity_Id
) return Boolean
2674 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2676 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2677 -- to mess with flags on both entities.
2679 return Has_Unreferenced
(E
)
2681 Has_Unreferenced
(Spec_Entity
(E
));
2684 return Has_Unreferenced
(E
);
2686 end Has_Pragma_Unreferenced_Check_Spec
;
2692 procedure Initialize
is
2694 Warnings_Off_Pragmas
.Init
;
2695 Unreferenced_Entities
.Init
;
2696 In_Out_Warnings
.Init
;
2699 ------------------------------------
2700 -- Never_Set_In_Source_Check_Spec --
2701 ------------------------------------
2703 function Never_Set_In_Source_Check_Spec
(E
: Entity_Id
) return Boolean is
2705 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2706 return Never_Set_In_Source
(E
)
2708 Never_Set_In_Source
(Spec_Entity
(E
));
2710 return Never_Set_In_Source
(E
);
2712 end Never_Set_In_Source_Check_Spec
;
2714 -------------------------------------
2715 -- Operand_Has_Warnings_Suppressed --
2716 -------------------------------------
2718 function Operand_Has_Warnings_Suppressed
(N
: Node_Id
) return Boolean is
2720 function Check_For_Warnings
(N
: Node_Id
) return Traverse_Result
;
2721 -- Function used to check one node to see if it is or was originally
2722 -- a reference to an entity for which Warnings are off. If so, Abandon
2723 -- is returned, otherwise OK_Orig is returned to continue the traversal
2724 -- of the original expression.
2726 function Traverse
is new Traverse_Func
(Check_For_Warnings
);
2727 -- Function used to traverse tree looking for warnings
2729 ------------------------
2730 -- Check_For_Warnings --
2731 ------------------------
2733 function Check_For_Warnings
(N
: Node_Id
) return Traverse_Result
is
2734 R
: constant Node_Id
:= Original_Node
(N
);
2737 if Nkind
(R
) in N_Has_Entity
2738 and then Present
(Entity
(R
))
2739 and then Has_Warnings_Off
(Entity
(R
))
2745 end Check_For_Warnings
;
2747 -- Start of processing for Operand_Has_Warnings_Suppressed
2750 return Traverse
(N
) = Abandon
;
2752 -- If any exception occurs, then something has gone wrong, and this is
2753 -- only a minor aesthetic issue anyway, so just say we did not find what
2754 -- we are looking for, rather than blow up.
2759 end Operand_Has_Warnings_Suppressed
;
2761 -----------------------------------------
2762 -- Output_Non_Modified_In_Out_Warnings --
2763 -----------------------------------------
2765 procedure Output_Non_Modified_In_Out_Warnings
is
2767 function No_Warn_On_In_Out
(E
: Entity_Id
) return Boolean;
2768 -- Given a formal parameter entity E, determines if there is a reason to
2769 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2770 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2771 -- if we have seen the address of the subprogram being taken, or if the
2772 -- subprogram is used as a generic actual (in the latter cases the
2773 -- context may force use of IN OUT, even if the parameter is not
2774 -- modifies for this particular case.
2776 -----------------------
2777 -- No_Warn_On_In_Out --
2778 -----------------------
2780 function No_Warn_On_In_Out
(E
: Entity_Id
) return Boolean is
2781 S
: constant Entity_Id
:= Scope
(E
);
2782 SE
: constant Entity_Id
:= Spec_Entity
(E
);
2785 -- Do not warn if address is taken, since funny business may be going
2786 -- on in treating the parameter indirectly as IN OUT.
2788 if Address_Taken
(S
)
2789 or else (Present
(SE
) and then Address_Taken
(Scope
(SE
)))
2793 -- Do not warn if used as a generic actual, since the generic may be
2794 -- what is forcing the use of an "unnecessary" IN OUT.
2796 elsif Used_As_Generic_Actual
(S
)
2797 or else (Present
(SE
) and then Used_As_Generic_Actual
(Scope
(SE
)))
2801 -- Else test warnings off
2803 elsif Warnings_Off_Check_Spec
(S
) then
2806 -- All tests for suppressing warning failed
2811 end No_Warn_On_In_Out
;
2813 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2816 -- Loop through entities for which a warning may be needed
2818 for J
in In_Out_Warnings
.First
.. In_Out_Warnings
.Last
loop
2820 E1
: constant Entity_Id
:= In_Out_Warnings
.Table
(J
);
2823 -- Suppress warning in specific cases (see details in comments for
2824 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2826 if Has_Pragma_Unmodified_Check_Spec
(E1
)
2827 or else No_Warn_On_In_Out
(E1
)
2831 -- Here we generate the warning
2834 -- If -gnatwc is set then output message that we could be IN
2836 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
2837 if Warn_On_Constant
then
2839 ("?u?formal parameter & is not modified!", E1
);
2841 ("\?u?mode could be IN instead of `IN OUT`!", E1
);
2843 -- We do not generate warnings for IN OUT parameters
2844 -- unless we have at least -gnatwu. This is deliberately
2845 -- inconsistent with the treatment of variables, but
2846 -- otherwise we get too many unexpected warnings in
2849 elsif Check_Unreferenced
then
2851 ("?u?formal parameter& is read but "
2852 & "never assigned!", E1
);
2856 -- Kill any other warnings on this entity, since this is the
2857 -- one that should dominate any other unreferenced warning.
2859 Set_Warnings_Off
(E1
);
2863 end Output_Non_Modified_In_Out_Warnings
;
2865 ----------------------------------------
2866 -- Output_Obsolescent_Entity_Warnings --
2867 ----------------------------------------
2869 procedure Output_Obsolescent_Entity_Warnings
(N
: Node_Id
; E
: Entity_Id
) is
2870 P
: constant Node_Id
:= Parent
(N
);
2876 -- Do not output message if we are the scope of standard. This means
2877 -- we have a reference from a context clause from when it is originally
2878 -- processed, and that's too early to tell whether it is an obsolescent
2879 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
2880 -- sure that we have a later call when the scope is available. This test
2881 -- also eliminates all messages for use clauses, which is fine (we do
2882 -- not want messages for use clauses, since they are always redundant
2883 -- with respect to the associated with clause).
2885 if S
= Standard_Standard
then
2889 -- Do not output message if we are in scope of an obsolescent package
2893 if Is_Obsolescent
(S
) then
2898 exit when S
= Standard_Standard
;
2901 -- Here we will output the message
2903 Error_Msg_Sloc
:= Sloc
(E
);
2905 -- Case of with clause
2907 if Nkind
(P
) = N_With_Clause
then
2908 if Ekind
(E
) = E_Package
then
2910 ("??with of obsolescent package& declared#", N
, E
);
2911 elsif Ekind
(E
) = E_Procedure
then
2913 ("??with of obsolescent procedure& declared#", N
, E
);
2916 ("??with of obsolescent function& declared#", N
, E
);
2919 -- If we do not have a with clause, then ignore any reference to an
2920 -- obsolescent package name. We only want to give the one warning of
2921 -- withing the package, not one each time it is used to qualify.
2923 elsif Ekind
(E
) = E_Package
then
2926 -- Procedure call statement
2928 elsif Nkind
(P
) = N_Procedure_Call_Statement
then
2930 ("??call to obsolescent procedure& declared#", N
, E
);
2934 elsif Nkind
(P
) = N_Function_Call
then
2936 ("??call to obsolescent function& declared#", N
, E
);
2938 -- Reference to obsolescent type
2940 elsif Is_Type
(E
) then
2942 ("??reference to obsolescent type& declared#", N
, E
);
2944 -- Reference to obsolescent component
2946 elsif Ekind_In
(E
, E_Component
, E_Discriminant
) then
2948 ("??reference to obsolescent component& declared#", N
, E
);
2950 -- Reference to obsolescent variable
2952 elsif Ekind
(E
) = E_Variable
then
2954 ("??reference to obsolescent variable& declared#", N
, E
);
2956 -- Reference to obsolescent constant
2958 elsif Ekind
(E
) = E_Constant
or else Ekind
(E
) in Named_Kind
then
2960 ("??reference to obsolescent constant& declared#", N
, E
);
2962 -- Reference to obsolescent enumeration literal
2964 elsif Ekind
(E
) = E_Enumeration_Literal
then
2966 ("??reference to obsolescent enumeration literal& declared#", N
, E
);
2968 -- Generic message for any other case we missed
2972 ("??reference to obsolescent entity& declared#", N
, E
);
2975 -- Output additional warning if present
2977 for J
in Obsolescent_Warnings
.First
.. Obsolescent_Warnings
.Last
loop
2978 if Obsolescent_Warnings
.Table
(J
).Ent
= E
then
2979 String_To_Name_Buffer
(Obsolescent_Warnings
.Table
(J
).Msg
);
2980 Error_Msg_Strlen
:= Name_Len
;
2981 Error_Msg_String
(1 .. Name_Len
) := Name_Buffer
(1 .. Name_Len
);
2982 Error_Msg_N
("\\??~", N
);
2986 end Output_Obsolescent_Entity_Warnings
;
2988 ----------------------------------
2989 -- Output_Unreferenced_Messages --
2990 ----------------------------------
2992 procedure Output_Unreferenced_Messages
is
2994 for J
in Unreferenced_Entities
.First
..
2995 Unreferenced_Entities
.Last
2997 Warn_On_Unreferenced_Entity
(Unreferenced_Entities
.Table
(J
));
2999 end Output_Unreferenced_Messages
;
3001 -----------------------------------------
3002 -- Output_Unused_Warnings_Off_Warnings --
3003 -----------------------------------------
3005 procedure Output_Unused_Warnings_Off_Warnings
is
3007 for J
in Warnings_Off_Pragmas
.First
.. Warnings_Off_Pragmas
.Last
loop
3009 Wentry
: Warnings_Off_Entry
renames Warnings_Off_Pragmas
.Table
(J
);
3010 N
: Node_Id
renames Wentry
.N
;
3011 E
: Node_Id
renames Wentry
.E
;
3014 -- Turn off Warnings_Off, or we won't get the warning
3016 Set_Warnings_Off
(E
, False);
3018 -- Nothing to do if pragma was used to suppress a general warning
3020 if Warnings_Off_Used
(E
) then
3023 -- If pragma was used both in unmodified and unreferenced contexts
3024 -- then that's as good as the general case, no warning.
3026 elsif Warnings_Off_Used_Unmodified
(E
)
3028 Warnings_Off_Used_Unreferenced
(E
)
3032 -- Used only in context where Unmodified would have worked
3034 elsif Warnings_Off_Used_Unmodified
(E
) then
3036 ("?W?could use Unmodified instead of "
3037 & "Warnings Off for &", Pragma_Identifier
(N
), E
);
3039 -- Used only in context where Unreferenced would have worked
3041 elsif Warnings_Off_Used_Unreferenced
(E
) then
3043 ("?W?could use Unreferenced instead of "
3044 & "Warnings Off for &", Pragma_Identifier
(N
), E
);
3050 ("?W?pragma Warnings Off for & unused, "
3051 & "could be omitted", N
, E
);
3055 end Output_Unused_Warnings_Off_Warnings
;
3057 ---------------------------
3058 -- Referenced_Check_Spec --
3059 ---------------------------
3061 function Referenced_Check_Spec
(E
: Entity_Id
) return Boolean is
3063 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3064 return Referenced
(E
) or else Referenced
(Spec_Entity
(E
));
3066 return Referenced
(E
);
3068 end Referenced_Check_Spec
;
3070 ----------------------------------
3071 -- Referenced_As_LHS_Check_Spec --
3072 ----------------------------------
3074 function Referenced_As_LHS_Check_Spec
(E
: Entity_Id
) return Boolean is
3076 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3077 return Referenced_As_LHS
(E
)
3078 or else Referenced_As_LHS
(Spec_Entity
(E
));
3080 return Referenced_As_LHS
(E
);
3082 end Referenced_As_LHS_Check_Spec
;
3084 --------------------------------------------
3085 -- Referenced_As_Out_Parameter_Check_Spec --
3086 --------------------------------------------
3088 function Referenced_As_Out_Parameter_Check_Spec
3089 (E
: Entity_Id
) return Boolean
3092 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3093 return Referenced_As_Out_Parameter
(E
)
3094 or else Referenced_As_Out_Parameter
(Spec_Entity
(E
));
3096 return Referenced_As_Out_Parameter
(E
);
3098 end Referenced_As_Out_Parameter_Check_Spec
;
3100 -----------------------------
3101 -- Warn_On_Known_Condition --
3102 -----------------------------
3104 procedure Warn_On_Known_Condition
(C
: Node_Id
) is
3106 Orig
: constant Node_Id
:= Original_Node
(C
);
3107 Test_Result
: Boolean;
3109 function Is_Known_Branch
return Boolean;
3110 -- If the type of the condition is Boolean, the constant value of the
3111 -- condition is a boolean literal. If the type is a derived boolean
3112 -- type, the constant is wrapped in a type conversion of the derived
3113 -- literal. If the value of the condition is not a literal, no warnings
3114 -- can be produced. This function returns True if the result can be
3115 -- determined, and Test_Result is set True/False accordingly. Otherwise
3116 -- False is returned, and Test_Result is unchanged.
3118 procedure Track
(N
: Node_Id
; Loc
: Node_Id
);
3119 -- Adds continuation warning(s) pointing to reason (assignment or test)
3120 -- for the operand of the conditional having a known value (or at least
3121 -- enough is known about the value to issue the warning). N is the node
3122 -- which is judged to have a known value. Loc is the warning location.
3124 ---------------------
3125 -- Is_Known_Branch --
3126 ---------------------
3128 function Is_Known_Branch
return Boolean is
3130 if Etype
(C
) = Standard_Boolean
3131 and then Is_Entity_Name
(C
)
3133 (Entity
(C
) = Standard_False
or else Entity
(C
) = Standard_True
)
3135 Test_Result
:= Entity
(C
) = Standard_True
;
3138 elsif Is_Boolean_Type
(Etype
(C
))
3139 and then Nkind
(C
) = N_Unchecked_Type_Conversion
3140 and then Is_Entity_Name
(Expression
(C
))
3141 and then Ekind
(Entity
(Expression
(C
))) = E_Enumeration_Literal
3144 Chars
(Entity
(Expression
(C
))) = Chars
(Standard_True
);
3150 end Is_Known_Branch
;
3156 procedure Track
(N
: Node_Id
; Loc
: Node_Id
) is
3157 Nod
: constant Node_Id
:= Original_Node
(N
);
3160 if Nkind
(Nod
) in N_Op_Compare
then
3161 Track
(Left_Opnd
(Nod
), Loc
);
3162 Track
(Right_Opnd
(Nod
), Loc
);
3164 elsif Is_Entity_Name
(Nod
)
3165 and then Is_Object
(Entity
(Nod
))
3168 CV
: constant Node_Id
:= Current_Value
(Entity
(Nod
));
3171 if Present
(CV
) then
3172 Error_Msg_Sloc
:= Sloc
(CV
);
3174 if Nkind
(CV
) not in N_Subexpr
then
3175 Error_Msg_N
("\\?(see test #)", Loc
);
3177 elsif Nkind
(Parent
(CV
)) =
3178 N_Case_Statement_Alternative
3180 Error_Msg_N
("\\?(see case alternative #)", Loc
);
3183 Error_Msg_N
("\\?(see assignment #)", Loc
);
3190 -- Start of processing for Warn_On_Known_Condition
3193 -- Adjust SCO condition if from source
3196 and then Comes_From_Source
(Orig
)
3197 and then Is_Known_Branch
3203 Atrue
:= Test_Result
;
3205 if Present
(Parent
(C
)) and then Nkind
(Parent
(C
)) = N_Op_Not
then
3209 Set_SCO_Condition
(Orig
, Atrue
);
3213 -- Argument replacement in an inlined body can make conditions static.
3214 -- Do not emit warnings in this case.
3216 if In_Inlined_Body
then
3220 if Constant_Condition_Warnings
3221 and then Is_Known_Branch
3222 and then Comes_From_Source
(Orig
)
3223 and then not In_Instance
3225 -- Don't warn if comparison of result of attribute against a constant
3226 -- value, since this is likely legitimate conditional compilation.
3228 if Nkind
(Orig
) in N_Op_Compare
3229 and then Compile_Time_Known_Value
(Right_Opnd
(Orig
))
3230 and then Nkind
(Original_Node
(Left_Opnd
(Orig
))) =
3231 N_Attribute_Reference
3236 -- See if this is in a statement or a declaration
3240 -- If tree is not attached, do not issue warning (this is very
3241 -- peculiar, and probably arises from some other error condition)
3246 -- If we are in a declaration, then no warning, since in practice
3247 -- conditionals in declarations are used for intended tests which
3248 -- may be known at compile time, e.g. things like
3250 -- x : constant Integer := 2 + (Word'Size = 32);
3252 -- And a warning is annoying in such cases
3254 elsif Nkind
(P
) in N_Declaration
3256 Nkind
(P
) in N_Later_Decl_Item
3260 -- Don't warn in assert or check pragma, since presumably tests in
3261 -- such a context are very definitely intended, and might well be
3262 -- known at compile time. Note that we have to test the original
3263 -- node, since assert pragmas get rewritten at analysis time.
3265 elsif Nkind
(Original_Node
(P
)) = N_Pragma
3266 and then Nam_In
(Pragma_Name
(Original_Node
(P
)), Name_Assert
,
3272 exit when Is_Statement
(P
);
3276 -- Here we issue the warning unless some sub-operand has warnings
3277 -- set off, in which case we suppress the warning for the node. If
3278 -- the original expression is an inequality, it has been expanded
3279 -- into a negation, and the value of the original expression is the
3280 -- negation of the equality. If the expression is an entity that
3281 -- appears within a negation, it is clearer to flag the negation
3282 -- itself, and report on its constant value.
3284 if not Operand_Has_Warnings_Suppressed
(C
) then
3286 True_Branch
: Boolean := Test_Result
;
3287 Cond
: Node_Id
:= C
;
3290 if Present
(Parent
(C
))
3291 and then Nkind
(Parent
(C
)) = N_Op_Not
3293 True_Branch
:= not True_Branch
;
3298 if Is_Entity_Name
(Original_Node
(C
))
3299 and then Nkind
(Cond
) /= N_Op_Not
3302 ("object & is always True?c?", Cond
, Original_Node
(C
));
3303 Track
(Original_Node
(C
), Cond
);
3306 Error_Msg_N
("condition is always True?c?", Cond
);
3311 Error_Msg_N
("condition is always False?c?", Cond
);
3317 end Warn_On_Known_Condition
;
3319 ---------------------------------------
3320 -- Warn_On_Modified_As_Out_Parameter --
3321 ---------------------------------------
3323 function Warn_On_Modified_As_Out_Parameter
(E
: Entity_Id
) return Boolean is
3326 (Warn_On_Modified_Unread
and then Is_Only_Out_Parameter
(E
))
3327 or else Warn_On_All_Unread_Out_Parameters
;
3328 end Warn_On_Modified_As_Out_Parameter
;
3330 ---------------------------------
3331 -- Warn_On_Overlapping_Actuals --
3332 ---------------------------------
3334 procedure Warn_On_Overlapping_Actuals
(Subp
: Entity_Id
; N
: Node_Id
) is
3335 Act1
, Act2
: Node_Id
;
3336 Form1
, Form2
: Entity_Id
;
3338 function Is_Covered_Formal
(Formal
: Node_Id
) return Boolean;
3339 -- Return True if Formal is covered by the rule
3341 function Refer_Same_Object
(Act1
, Act2
: Node_Id
) return Boolean;
3342 -- Two names are known to refer to the same object if the two names
3343 -- are known to denote the same object; or one of the names is a
3344 -- selected_component, indexed_component, or slice and its prefix is
3345 -- known to refer to the same object as the other name; or one of the
3346 -- two names statically denotes a renaming declaration whose renamed
3347 -- object_name is known to refer to the same object as the other name
3348 -- (RM 6.4.1(6.11/3))
3350 -----------------------
3351 -- Refer_Same_Object --
3352 -----------------------
3354 function Refer_Same_Object
(Act1
, Act2
: Node_Id
) return Boolean is
3356 return Denotes_Same_Object
(Act1
, Act2
)
3357 or else Denotes_Same_Prefix
(Act1
, Act2
);
3358 end Refer_Same_Object
;
3360 -----------------------
3361 -- Is_Covered_Formal --
3362 -----------------------
3364 function Is_Covered_Formal
(Formal
: Node_Id
) return Boolean is
3367 Ekind_In
(Formal
, E_Out_Parameter
, E_In_Out_Parameter
)
3368 and then (Is_Elementary_Type
(Etype
(Formal
))
3369 or else Is_Record_Type
(Etype
(Formal
))
3370 or else Is_Array_Type
(Etype
(Formal
)));
3371 end Is_Covered_Formal
;
3374 if Ada_Version
< Ada_2012
and then not Warn_On_Overlap
then
3378 -- Exclude calls rewritten as enumeration literals
3380 if Nkind
(N
) not in N_Subprogram_Call
3381 and then Nkind
(N
) /= N_Entry_Call_Statement
3386 -- If a call C has two or more parameters of mode in out or out that are
3387 -- of an elementary type, then the call is legal only if for each name
3388 -- N that is passed as a parameter of mode in out or out to the call C,
3389 -- there is no other name among the other parameters of mode in out or
3390 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3392 -- If appropriate warning switch is set, we also report warnings on
3393 -- overlapping parameters that are record types or array types.
3395 Form1
:= First_Formal
(Subp
);
3396 Act1
:= First_Actual
(N
);
3397 while Present
(Form1
) and then Present
(Act1
) loop
3398 if Is_Covered_Formal
(Form1
) then
3399 Form2
:= First_Formal
(Subp
);
3400 Act2
:= First_Actual
(N
);
3401 while Present
(Form2
) and then Present
(Act2
) loop
3403 and then Is_Covered_Formal
(Form2
)
3404 and then Refer_Same_Object
(Act1
, Act2
)
3406 -- Guard against previous errors
3409 or else No
(Etype
(Act1
))
3410 or else No
(Etype
(Act2
))
3414 -- If the actual is a function call in prefix notation,
3415 -- there is no real overlap.
3417 elsif Nkind
(Act2
) = N_Function_Call
then
3420 -- If type is not by-copy, assume that aliasing is intended
3423 Present
(Underlying_Type
(Etype
(Form1
)))
3425 (Is_By_Reference_Type
(Underlying_Type
(Etype
(Form1
)))
3427 Convention
(Underlying_Type
(Etype
(Form1
))) =
3428 Convention_Ada_Pass_By_Reference
)
3432 -- Under Ada 2012 we only report warnings on overlapping
3433 -- arrays and record types if switch is set.
3435 elsif Ada_Version
>= Ada_2012
3436 and then not Is_Elementary_Type
(Etype
(Form1
))
3437 and then not Warn_On_Overlap
3441 -- Here we may need to issue overlap message
3446 -- Overlap checking is an error only in Ada 2012. For
3447 -- earlier versions of Ada, this is a warning.
3449 Ada_Version
< Ada_2012
3451 -- Overlap is only illegal in Ada 2012 in the case of
3452 -- elementary types (passed by copy). For other types,
3453 -- we always have a warning in all Ada versions.
3455 or else not Is_Elementary_Type
(Etype
(Form1
))
3457 -- Finally, debug flag -gnatd.E changes the error to a
3458 -- warning even in Ada 2012 mode.
3460 or else Error_To_Warning
;
3467 -- Find matching actual
3469 Act
:= First_Actual
(N
);
3470 Form
:= First_Formal
(Subp
);
3471 while Act
/= Act2
loop
3476 if Is_Elementary_Type
(Etype
(Act1
))
3477 and then Ekind
(Form2
) = E_In_Parameter
3479 null; -- No real aliasing
3481 elsif Is_Elementary_Type
(Etype
(Act2
))
3482 and then Ekind
(Form2
) = E_In_Parameter
3486 -- If the call was written in prefix notation, and
3487 -- thus its prefix before rewriting was a selected
3488 -- component, count only visible actuals in the call.
3490 elsif Is_Entity_Name
(First_Actual
(N
))
3491 and then Nkind
(Original_Node
(N
)) = Nkind
(N
)
3492 and then Nkind
(Name
(Original_Node
(N
))) =
3493 N_Selected_Component
3495 Is_Entity_Name
(Prefix
(Name
(Original_Node
(N
))))
3497 Entity
(Prefix
(Name
(Original_Node
(N
)))) =
3498 Entity
(First_Actual
(N
))
3500 if Act1
= First_Actual
(N
) then
3502 ("<`IN OUT` prefix overlaps with "
3503 & "actual for&", Act1
, Form
);
3506 -- For greater clarity, give name of formal
3508 Error_Msg_Node_2
:= Form
;
3510 ("<writable actual for & overlaps with "
3511 & "actual for&", Act1
, Form
);
3515 -- For greater clarity, give name of formal
3517 Error_Msg_Node_2
:= Form
;
3519 -- This is one of the messages
3522 ("<writable actual for & overlaps with "
3523 & "actual for&", Act1
, Form1
);
3531 Next_Formal
(Form2
);
3536 Next_Formal
(Form1
);
3539 end Warn_On_Overlapping_Actuals
;
3541 ------------------------------
3542 -- Warn_On_Suspicious_Index --
3543 ------------------------------
3545 procedure Warn_On_Suspicious_Index
(Name
: Entity_Id
; X
: Node_Id
) is
3548 -- Set to lower bound for a suspicious type
3551 -- Entity for array reference
3556 function Is_Suspicious_Type
(Typ
: Entity_Id
) return Boolean;
3557 -- Tests to see if Typ is a type for which we may have a suspicious
3558 -- index, namely an unconstrained array type, whose lower bound is
3559 -- either zero or one. If so, True is returned, and Low_Bound is set
3560 -- to this lower bound. If not, False is returned, and Low_Bound is
3561 -- undefined on return.
3563 -- For now, we limit this to standard string types, so any other
3564 -- unconstrained types return False. We may change our minds on this
3565 -- later on, but strings seem the most important case.
3567 procedure Test_Suspicious_Index
;
3568 -- Test if index is of suspicious type and if so, generate warning
3570 ------------------------
3571 -- Is_Suspicious_Type --
3572 ------------------------
3574 function Is_Suspicious_Type
(Typ
: Entity_Id
) return Boolean is
3578 if Is_Array_Type
(Typ
)
3579 and then not Is_Constrained
(Typ
)
3580 and then Number_Dimensions
(Typ
) = 1
3581 and then (Root_Type
(Typ
) = Standard_String
3583 Root_Type
(Typ
) = Standard_Wide_String
3585 Root_Type
(Typ
) = Standard_Wide_Wide_String
)
3586 and then not Has_Warnings_Off
(Typ
)
3588 LB
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3590 if Compile_Time_Known_Value
(LB
) then
3591 Low_Bound
:= Expr_Value
(LB
);
3592 return Low_Bound
= Uint_0
or else Low_Bound
= Uint_1
;
3597 end Is_Suspicious_Type
;
3599 ---------------------------
3600 -- Test_Suspicious_Index --
3601 ---------------------------
3603 procedure Test_Suspicious_Index
is
3605 function Length_Reference
(N
: Node_Id
) return Boolean;
3606 -- Check if node N is of the form Name'Length
3609 -- Generate first warning line
3611 ----------------------
3612 -- Length_Reference --
3613 ----------------------
3615 function Length_Reference
(N
: Node_Id
) return Boolean is
3616 R
: constant Node_Id
:= Original_Node
(N
);
3619 Nkind
(R
) = N_Attribute_Reference
3620 and then Attribute_Name
(R
) = Name_Length
3621 and then Is_Entity_Name
(Prefix
(R
))
3622 and then Entity
(Prefix
(R
)) = Ent
;
3623 end Length_Reference
;
3631 Error_Msg_Uint_1
:= Low_Bound
;
3632 Error_Msg_FE
-- CODEFIX
3633 ("?w?index for& may assume lower bound of^", X
, Ent
);
3636 -- Start of processing for Test_Suspicious_Index
3639 -- Nothing to do if subscript does not come from source (we don't
3640 -- want to give garbage warnings on compiler expanded code, e.g. the
3641 -- loops generated for slice assignments. Such junk warnings would
3642 -- be placed on source constructs with no subscript in sight).
3644 if not Comes_From_Source
(Original_Node
(X
)) then
3648 -- Case where subscript is a constant integer
3650 if Nkind
(X
) = N_Integer_Literal
then
3653 -- Case where original form of subscript is an integer literal
3655 if Nkind
(Original_Node
(X
)) = N_Integer_Literal
then
3656 if Intval
(X
) = Low_Bound
then
3657 Error_Msg_FE
-- CODEFIX
3658 ("\?w?suggested replacement: `&''First`", X
, Ent
);
3660 Error_Msg_Uint_1
:= Intval
(X
) - Low_Bound
;
3661 Error_Msg_FE
-- CODEFIX
3662 ("\?w?suggested replacement: `&''First + ^`", X
, Ent
);
3666 -- Case where original form of subscript is more complex
3669 -- Build string X'First - 1 + expression where the expression
3670 -- is the original subscript. If the expression starts with "1
3671 -- + ", then the "- 1 + 1" is elided.
3673 Error_Msg_String
(1 .. 13) := "'First - 1 + ";
3674 Error_Msg_Strlen
:= 13;
3677 Sref
: Source_Ptr
:= Sloc
(First_Node
(Original_Node
(X
)));
3678 Tref
: constant Source_Buffer_Ptr
:=
3679 Source_Text
(Get_Source_File_Index
(Sref
));
3680 -- Tref (Sref) is used to scan the subscript
3683 -- Parentheses counter when scanning subscript
3686 -- Tref (Sref) points to start of subscript
3688 -- Elide - 1 if subscript starts with 1 +
3690 if Tref
(Sref
.. Sref
+ 2) = "1 +" then
3691 Error_Msg_Strlen
:= Error_Msg_Strlen
- 6;
3694 elsif Tref
(Sref
.. Sref
+ 1) = "1+" then
3695 Error_Msg_Strlen
:= Error_Msg_Strlen
- 6;
3699 -- Now we will copy the subscript to the string buffer
3703 -- Count parens, exit if terminating right paren. Note
3704 -- check to ignore paren appearing as character literal.
3706 if Tref
(Sref
+ 1) = '''
3708 Tref
(Sref
- 1) = '''
3712 if Tref
(Sref
) = '(' then
3714 elsif Tref
(Sref
) = ')' then
3720 -- Done if terminating double dot (slice case)
3723 and then (Tref
(Sref
.. Sref
+ 1) = ".."
3725 Tref
(Sref
.. Sref
+ 2) = " ..");
3727 -- Quit if we have hit EOF character, something wrong
3729 if Tref
(Sref
) = EOF
then
3733 -- String literals are too much of a pain to handle
3735 if Tref
(Sref
) = '"' or else Tref
(Sref
) = '%' then
3739 -- If we have a 'Range reference, then this is a case
3740 -- where we cannot easily give a replacement. Don't try.
3742 if Tref
(Sref
.. Sref
+ 4) = "range"
3743 and then Tref
(Sref
- 1) < 'A'
3744 and then Tref
(Sref
+ 5) < 'A'
3749 -- Else store next character
3751 Error_Msg_Strlen
:= Error_Msg_Strlen
+ 1;
3752 Error_Msg_String
(Error_Msg_Strlen
) := Tref
(Sref
);
3755 -- If we get more than 40 characters then the expression
3756 -- is too long to copy, or something has gone wrong. In
3757 -- either case, just skip the attempt at a suggested fix.
3759 if Error_Msg_Strlen
> 40 then
3765 -- Replacement subscript is now in string buffer
3767 Error_Msg_FE
-- CODEFIX
3768 ("\?w?suggested replacement: `&~`", Original_Node
(X
), Ent
);
3771 -- Case where subscript is of the form X'Length
3773 elsif Length_Reference
(X
) then
3775 Error_Msg_Node_2
:= Ent
;
3777 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3780 -- Case where subscript is of the form X'Length - expression
3782 elsif Nkind
(X
) = N_Op_Subtract
3783 and then Length_Reference
(Left_Opnd
(X
))
3786 Error_Msg_Node_2
:= Ent
;
3788 ("\?w?suggest replacement of `&''Length` by `&''Last`",
3789 Left_Opnd
(X
), Ent
);
3791 end Test_Suspicious_Index
;
3793 -- Start of processing for Warn_On_Suspicious_Index
3796 -- Only process if warnings activated
3798 if Warn_On_Assumed_Low_Bound
then
3800 -- Test if array is simple entity name
3802 if Is_Entity_Name
(Name
) then
3804 -- Test if array is parameter of unconstrained string type
3806 Ent
:= Entity
(Name
);
3810 and then Is_Suspicious_Type
(Typ
)
3811 and then not Low_Bound_Tested
(Ent
)
3813 Test_Suspicious_Index
;
3817 end Warn_On_Suspicious_Index
;
3819 --------------------------------------
3820 -- Warn_On_Unassigned_Out_Parameter --
3821 --------------------------------------
3823 procedure Warn_On_Unassigned_Out_Parameter
3824 (Return_Node
: Node_Id
;
3825 Scope_Id
: Entity_Id
)
3831 -- Ignore if procedure or return statement does not come from source
3833 if not Comes_From_Source
(Scope_Id
)
3834 or else not Comes_From_Source
(Return_Node
)
3839 -- Loop through formals
3841 Form
:= First_Formal
(Scope_Id
);
3842 while Present
(Form
) loop
3844 -- We are only interested in OUT parameters that come from source
3845 -- and are never set in the source, and furthermore only in scalars
3846 -- since non-scalars generate too many false positives.
3848 if Ekind
(Form
) = E_Out_Parameter
3849 and then Never_Set_In_Source_Check_Spec
(Form
)
3850 and then Is_Scalar_Type
(Etype
(Form
))
3851 and then not Present
(Unset_Reference
(Form
))
3853 -- Before we issue the warning, an add ad hoc defence against the
3854 -- most common case of false positives with this warning which is
3855 -- the case where there is a Boolean OUT parameter that has been
3856 -- set, and whose meaning is "ignore the values of the other
3857 -- parameters". We can't of course reliably tell this case at
3858 -- compile time, but the following test kills a lot of false
3859 -- positives, without generating a significant number of false
3860 -- negatives (missed real warnings).
3862 Form2
:= First_Formal
(Scope_Id
);
3863 while Present
(Form2
) loop
3864 if Ekind
(Form2
) = E_Out_Parameter
3865 and then Root_Type
(Etype
(Form2
)) = Standard_Boolean
3866 and then not Never_Set_In_Source_Check_Spec
(Form2
)
3871 Next_Formal
(Form2
);
3874 -- Here all conditions are met, record possible unset reference
3876 Set_Unset_Reference
(Form
, Return_Node
);
3881 end Warn_On_Unassigned_Out_Parameter
;
3883 ---------------------------------
3884 -- Warn_On_Unreferenced_Entity --
3885 ---------------------------------
3887 procedure Warn_On_Unreferenced_Entity
3888 (Spec_E
: Entity_Id
;
3889 Body_E
: Entity_Id
:= Empty
)
3891 E
: Entity_Id
:= Spec_E
;
3894 if not Referenced_Check_Spec
(E
)
3895 and then not Has_Pragma_Unreferenced_Check_Spec
(E
)
3896 and then not Warnings_Off_Check_Spec
(E
)
3901 -- Case of variable that is assigned but not read. We suppress
3902 -- the message if the variable is volatile, has an address
3903 -- clause, is aliased, or is a renaming, or is imported.
3905 if Referenced_As_LHS_Check_Spec
(E
)
3906 and then No
(Address_Clause
(E
))
3907 and then not Is_Volatile
(E
)
3909 if Warn_On_Modified_Unread
3910 and then not Is_Imported
(E
)
3911 and then not Is_Aliased
(E
)
3912 and then No
(Renamed_Object
(E
))
3914 if not Has_Pragma_Unmodified_Check_Spec
(E
) then
3915 Error_Msg_N
-- CODEFIX
3916 ("?u?variable & is assigned but never read!", E
);
3919 Set_Last_Assignment
(E
, Empty
);
3922 -- Normal case of neither assigned nor read (exclude variables
3923 -- referenced as out parameters, since we already generated
3924 -- appropriate warnings at the call point in this case).
3926 elsif not Referenced_As_Out_Parameter
(E
) then
3928 -- We suppress the message for types for which a valid
3929 -- pragma Unreferenced_Objects has been given, otherwise
3930 -- we go ahead and give the message.
3932 if not Has_Pragma_Unreferenced_Objects
(Etype
(E
)) then
3934 -- Distinguish renamed case in message
3936 if Present
(Renamed_Object
(E
))
3937 and then Comes_From_Source
(Renamed_Object
(E
))
3939 Error_Msg_N
-- CODEFIX
3940 ("?u?renamed variable & is not referenced!", E
);
3942 Error_Msg_N
-- CODEFIX
3943 ("?u?variable & is not referenced!", E
);
3949 if Present
(Renamed_Object
(E
))
3950 and then Comes_From_Source
(Renamed_Object
(E
))
3952 Error_Msg_N
-- CODEFIX
3953 ("?u?renamed constant & is not referenced!", E
);
3955 Error_Msg_N
-- CODEFIX
3956 ("?u?constant & is not referenced!", E
);
3959 when E_In_Parameter |
3960 E_In_Out_Parameter
=>
3962 -- Do not emit message for formals of a renaming, because
3963 -- they are never referenced explicitly.
3965 if Nkind
(Original_Node
(Unit_Declaration_Node
(Scope
(E
)))) /=
3966 N_Subprogram_Renaming_Declaration
3968 -- Suppress this message for an IN OUT parameter of a
3969 -- non-scalar type, since it is normal to have only an
3970 -- assignment in such a case.
3972 if Ekind
(E
) = E_In_Parameter
3973 or else not Referenced_As_LHS_Check_Spec
(E
)
3974 or else Is_Scalar_Type
(Etype
(E
))
3976 if Present
(Body_E
) then
3980 if not Is_Trivial_Subprogram
(Scope
(E
)) then
3981 Error_Msg_NE
-- CODEFIX
3982 ("?u?formal parameter & is not referenced!",
3988 when E_Out_Parameter
=>
3991 when E_Discriminant
=>
3992 Error_Msg_N
("?u?discriminant & is not referenced!", E
);
3994 when E_Named_Integer |
3996 Error_Msg_N
-- CODEFIX
3997 ("?u?named number & is not referenced!", E
);
3999 when Formal_Object_Kind
=>
4000 Error_Msg_N
-- CODEFIX
4001 ("?u?formal object & is not referenced!", E
);
4003 when E_Enumeration_Literal
=>
4004 Error_Msg_N
-- CODEFIX
4005 ("?u?literal & is not referenced!", E
);
4008 Error_Msg_N
-- CODEFIX
4009 ("?u?function & is not referenced!", E
);
4012 Error_Msg_N
-- CODEFIX
4013 ("?u?procedure & is not referenced!", E
);
4016 Error_Msg_N
-- CODEFIX
4017 ("?u?package & is not referenced!", E
);
4020 Error_Msg_N
-- CODEFIX
4021 ("?u?exception & is not referenced!", E
);
4024 Error_Msg_N
-- CODEFIX
4025 ("?u?label & is not referenced!", E
);
4027 when E_Generic_Procedure
=>
4028 Error_Msg_N
-- CODEFIX
4029 ("?u?generic procedure & is never instantiated!", E
);
4031 when E_Generic_Function
=>
4032 Error_Msg_N
-- CODEFIX
4033 ("?u?generic function & is never instantiated!", E
);
4036 Error_Msg_N
-- CODEFIX
4037 ("?u?type & is not referenced!", E
);
4040 Error_Msg_N
-- CODEFIX
4041 ("?u?& is not referenced!", E
);
4044 -- Kill warnings on the entity on which the message has been posted
4046 Set_Warnings_Off
(E
);
4048 end Warn_On_Unreferenced_Entity
;
4050 --------------------------------
4051 -- Warn_On_Useless_Assignment --
4052 --------------------------------
4054 procedure Warn_On_Useless_Assignment
4056 N
: Node_Id
:= Empty
)
4061 function Check_Ref
(N
: Node_Id
) return Traverse_Result
;
4062 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4063 -- the entity in question is found.
4065 function Test_No_Refs
is new Traverse_Func
(Check_Ref
);
4071 function Check_Ref
(N
: Node_Id
) return Traverse_Result
is
4073 -- Check reference to our identifier. We use name equality here
4074 -- because the exception handlers have not yet been analyzed. This
4075 -- is not quite right, but it really does not matter that we fail
4076 -- to output the warning in some obscure cases of name clashes.
4078 if Nkind
(N
) = N_Identifier
4079 and then Chars
(N
) = Chars
(Ent
)
4087 -- Start of processing for Warn_On_Useless_Assignment
4090 -- Check if this is a case we want to warn on, a scalar or access
4091 -- variable with the last assignment field set, with warnings enabled,
4092 -- and which is not imported or exported. We also check that it is OK
4093 -- to capture the value. We are not going to capture any value, but
4094 -- the warning message depends on the same kind of conditions.
4096 if Is_Assignable
(Ent
)
4097 and then not Is_Return_Object
(Ent
)
4098 and then Present
(Last_Assignment
(Ent
))
4099 and then not Is_Imported
(Ent
)
4100 and then not Is_Exported
(Ent
)
4101 and then Safe_To_Capture_Value
(N
, Ent
)
4102 and then not Has_Pragma_Unreferenced_Check_Spec
(Ent
)
4104 -- Before we issue the message, check covering exception handlers.
4105 -- Search up tree for enclosing statement sequences and handlers.
4107 P
:= Parent
(Last_Assignment
(Ent
));
4108 while Present
(P
) loop
4110 -- Something is really wrong if we don't find a handled statement
4111 -- sequence, so just suppress the warning.
4114 Set_Last_Assignment
(Ent
, Empty
);
4117 -- When we hit a package/subprogram body, issue warning and exit
4119 elsif Nkind
(P
) = N_Subprogram_Body
4120 or else Nkind
(P
) = N_Package_Body
4122 -- Case of assigned value never referenced
4126 LA
: constant Node_Id
:= Last_Assignment
(Ent
);
4129 -- Don't give this for OUT and IN OUT formals, since
4130 -- clearly caller may reference the assigned value. Also
4131 -- never give such warnings for internal variables.
4133 if Ekind
(Ent
) = E_Variable
4134 and then not Is_Internal_Name
(Chars
(Ent
))
4136 -- Give appropriate message, distinguishing between
4137 -- assignment statements and out parameters.
4139 if Nkind_In
(Parent
(LA
), N_Procedure_Call_Statement
,
4140 N_Parameter_Association
)
4143 ("?m?& modified by call, but value never "
4144 & "referenced", LA
, Ent
);
4147 Error_Msg_NE
-- CODEFIX
4148 ("?m?useless assignment to&, value never "
4149 & "referenced!", LA
, Ent
);
4154 -- Case of assigned value overwritten
4158 LA
: constant Node_Id
:= Last_Assignment
(Ent
);
4161 Error_Msg_Sloc
:= Sloc
(N
);
4163 -- Give appropriate message, distinguishing between
4164 -- assignment statements and out parameters.
4166 if Nkind_In
(Parent
(LA
), N_Procedure_Call_Statement
,
4167 N_Parameter_Association
)
4170 ("?m?& modified by call, but value overwritten #!",
4173 Error_Msg_NE
-- CODEFIX
4174 ("?m?useless assignment to&, value overwritten #!",
4180 -- Clear last assignment indication and we are done
4182 Set_Last_Assignment
(Ent
, Empty
);
4185 -- Enclosing handled sequence of statements
4187 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
then
4189 -- Check exception handlers present
4191 if Present
(Exception_Handlers
(P
)) then
4193 -- If we are not at the top level, we regard an inner
4194 -- exception handler as a decisive indicator that we should
4195 -- not generate the warning, since the variable in question
4196 -- may be accessed after an exception in the outer block.
4198 if Nkind
(Parent
(P
)) /= N_Subprogram_Body
4199 and then Nkind
(Parent
(P
)) /= N_Package_Body
4201 Set_Last_Assignment
(Ent
, Empty
);
4204 -- Otherwise we are at the outer level. An exception
4205 -- handler is significant only if it references the
4206 -- variable in question, or if the entity in question
4207 -- is an OUT or IN OUT parameter, which which case
4208 -- the caller can reference it after the exception
4209 -- handler completes.
4212 if Is_Formal
(Ent
) then
4213 Set_Last_Assignment
(Ent
, Empty
);
4217 X
:= First
(Exception_Handlers
(P
));
4218 while Present
(X
) loop
4219 if Test_No_Refs
(X
) = Abandon
then
4220 Set_Last_Assignment
(Ent
, Empty
);
4234 end Warn_On_Useless_Assignment
;
4236 ---------------------------------
4237 -- Warn_On_Useless_Assignments --
4238 ---------------------------------
4240 procedure Warn_On_Useless_Assignments
(E
: Entity_Id
) is
4243 if Warn_On_Modified_Unread
4244 and then In_Extended_Main_Source_Unit
(E
)
4246 Ent
:= First_Entity
(E
);
4247 while Present
(Ent
) loop
4248 Warn_On_Useless_Assignment
(Ent
);
4252 end Warn_On_Useless_Assignments
;
4254 -----------------------------
4255 -- Warnings_Off_Check_Spec --
4256 -----------------------------
4258 function Warnings_Off_Check_Spec
(E
: Entity_Id
) return Boolean is
4260 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
4262 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4263 -- to mess with flags on both entities.
4265 return Has_Warnings_Off
(E
)
4267 Has_Warnings_Off
(Spec_Entity
(E
));
4270 return Has_Warnings_Off
(E
);
4272 end Warnings_Off_Check_Spec
;