1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1999-2017, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree
; use Atree
;
27 with Debug
; use Debug
;
28 with Einfo
; use Einfo
;
29 with Errout
; use Errout
;
30 with Exp_Code
; use Exp_Code
;
32 with Lib
.Xref
; use Lib
.Xref
;
33 with Namet
; use Namet
;
34 with Nlists
; use Nlists
;
36 with Par_SCO
; use Par_SCO
;
37 with Rtsfind
; use Rtsfind
;
39 with Sem_Ch8
; use Sem_Ch8
;
40 with Sem_Aux
; use Sem_Aux
;
41 with Sem_Eval
; use Sem_Eval
;
42 with Sem_Prag
; use Sem_Prag
;
43 with Sem_Util
; use Sem_Util
;
44 with Sinfo
; use Sinfo
;
45 with Sinput
; use Sinput
;
46 with Snames
; use Snames
;
47 with Stand
; use Stand
;
48 with Stringt
; use Stringt
;
49 with Tbuild
; use Tbuild
;
50 with Uintp
; use Uintp
;
52 package body Sem_Warn
is
54 -- The following table collects Id's of entities that are potentially
55 -- unreferenced. See Check_Unset_Reference for further details.
56 -- ??? Check_Unset_Reference has zero information about this table.
58 package Unreferenced_Entities
is new Table
.Table
(
59 Table_Component_Type
=> Entity_Id
,
60 Table_Index_Type
=> Nat
,
62 Table_Initial
=> Alloc
.Unreferenced_Entities_Initial
,
63 Table_Increment
=> Alloc
.Unreferenced_Entities_Increment
,
64 Table_Name
=> "Unreferenced_Entities");
66 -- The following table collects potential warnings for IN OUT parameters
67 -- that are referenced but not modified. These warnings are processed when
68 -- the front end calls the procedure Output_Non_Modified_In_Out_Warnings.
69 -- The reason that we defer output of these messages is that we want to
70 -- detect the case where the relevant procedure is used as a generic actual
71 -- in an instantiation, since we suppress the warnings in this case. The
72 -- flag Used_As_Generic_Actual will be set in this case, but only at the
73 -- point of usage. Similarly, we suppress the message if the address of the
74 -- procedure is taken, where the flag Address_Taken may be set later.
76 package In_Out_Warnings
is new Table
.Table
(
77 Table_Component_Type
=> Entity_Id
,
78 Table_Index_Type
=> Nat
,
80 Table_Initial
=> Alloc
.In_Out_Warnings_Initial
,
81 Table_Increment
=> Alloc
.In_Out_Warnings_Increment
,
82 Table_Name
=> "In_Out_Warnings");
84 --------------------------------------------------------
85 -- Handling of Warnings Off, Unmodified, Unreferenced --
86 --------------------------------------------------------
88 -- The functions Has_Warnings_Off, Has_Unmodified, Has_Unreferenced must
89 -- generally be used instead of Warnings_Off, Has_Pragma_Unmodified and
90 -- Has_Pragma_Unreferenced, as noted in the specs in Einfo.
92 -- In order to avoid losing warnings in -gnatw.w (warn on unnecessary
93 -- warnings off pragma) mode, i.e. to avoid false negatives, the code
94 -- must follow some important rules.
96 -- Call these functions as late as possible, after completing all other
97 -- tests, just before the warnings is given. For example, don't write:
99 -- if not Has_Warnings_Off (E)
100 -- and then some-other-predicate-on-E then ..
102 -- Instead the following is preferred
104 -- if some-other-predicate-on-E
105 -- and then Has_Warnings_Off (E)
107 -- This way if some-other-predicate is false, we avoid a false indication
108 -- that a Warnings (Off, E) pragma was useful in preventing a warning.
110 -- The second rule is that if both Has_Unmodified and Has_Warnings_Off, or
111 -- Has_Unreferenced and Has_Warnings_Off are called, make sure that the
112 -- call to Has_Unmodified/Has_Unreferenced comes first, this way we record
113 -- that the Warnings (Off) could have been Unreferenced or Unmodified. In
114 -- fact Has_Unmodified/Has_Unreferenced includes a test for Warnings Off,
115 -- and so a subsequent test is not needed anyway (though it is harmless).
117 -----------------------
118 -- Local Subprograms --
119 -----------------------
121 function Generic_Package_Spec_Entity
(E
: Entity_Id
) return Boolean;
122 -- This returns true if the entity E is declared within a generic package.
123 -- The point of this is to detect variables which are not assigned within
124 -- the generic, but might be assigned outside the package for any given
125 -- instance. These are cases where we leave the warnings to be posted for
126 -- the instance, when we will know more.
128 function Goto_Spec_Entity
(E
: Entity_Id
) return Entity_Id
;
129 -- If E is a parameter entity for a subprogram body, then this function
130 -- returns the corresponding spec entity, if not, E is returned unchanged.
132 function Has_Pragma_Unmodified_Check_Spec
(E
: Entity_Id
) return Boolean;
133 -- Tests Has_Pragma_Unmodified flag for entity E. If E is not a formal,
134 -- this is simply the setting of the flag Has_Pragma_Unmodified. If E is
135 -- a body formal, the setting of the flag in the corresponding spec is
136 -- also checked (and True returned if either flag is True).
138 function Has_Pragma_Unreferenced_Check_Spec
(E
: Entity_Id
) return Boolean;
139 -- Tests Has_Pragma_Unreferenced flag for entity E. If E is not a formal,
140 -- this is simply the setting of the flag Has_Pragma_Unreferenced. If E is
141 -- a body formal, the setting of the flag in the corresponding spec is
142 -- also checked (and True returned if either flag is True).
144 function Is_Attribute_And_Known_Value_Comparison
145 (Op
: Node_Id
) return Boolean;
146 -- Determine whether operator Op denotes a comparison where the left
147 -- operand is an attribute reference and the value of the right operand is
148 -- known at compile time.
150 function Never_Set_In_Source_Check_Spec
(E
: Entity_Id
) return Boolean;
151 -- Tests Never_Set_In_Source status for entity E. If E is not a formal,
152 -- this is simply the setting of the flag Never_Set_In_Source. If E is
153 -- a body formal, the setting of the flag in the corresponding spec is
154 -- also checked (and False returned if either flag is False).
156 function Operand_Has_Warnings_Suppressed
(N
: Node_Id
) return Boolean;
157 -- This function traverses the expression tree represented by the node N
158 -- and determines if any sub-operand is a reference to an entity for which
159 -- the Warnings_Off flag is set. True is returned if such an entity is
160 -- encountered, and False otherwise.
162 function Referenced_Check_Spec
(E
: Entity_Id
) return Boolean;
163 -- Tests Referenced status for entity E. If E is not a formal, this is
164 -- simply the setting of the flag Referenced. If E is a body formal, the
165 -- setting of the flag in the corresponding spec is also checked (and True
166 -- returned if either flag is True).
168 function Referenced_As_LHS_Check_Spec
(E
: Entity_Id
) return Boolean;
169 -- Tests Referenced_As_LHS status for entity E. If E is not a formal, this
170 -- is simply the setting of the flag Referenced_As_LHS. If E is a body
171 -- formal, the setting of the flag in the corresponding spec is also
172 -- checked (and True returned if either flag is True).
174 function Referenced_As_Out_Parameter_Check_Spec
175 (E
: Entity_Id
) return Boolean;
176 -- Tests Referenced_As_Out_Parameter status for entity E. If E is not a
177 -- formal, this is simply the setting of Referenced_As_Out_Parameter. If E
178 -- is a body formal, the setting of the flag in the corresponding spec is
179 -- also checked (and True returned if either flag is True).
181 procedure Warn_On_Unreferenced_Entity
183 Body_E
: Entity_Id
:= Empty
);
184 -- Output warnings for unreferenced entity E. For the case of an entry
185 -- formal, Body_E is the corresponding body entity for a particular
186 -- accept statement, and the message is posted on Body_E. In all other
187 -- cases, Body_E is ignored and must be Empty.
189 function Warnings_Off_Check_Spec
(E
: Entity_Id
) return Boolean;
190 -- Returns True if Warnings_Off is set for the entity E or (in the case
191 -- where there is a Spec_Entity), Warnings_Off is set for the Spec_Entity.
193 --------------------------
194 -- Check_Code_Statement --
195 --------------------------
197 procedure Check_Code_Statement
(N
: Node_Id
) is
199 -- If volatile, nothing to worry about
201 if Is_Asm_Volatile
(N
) then
205 -- Warn if no input or no output
207 Setup_Asm_Inputs
(N
);
209 if No
(Asm_Input_Value
) then
211 ("??code statement with no inputs should usually be Volatile!", N
);
215 Setup_Asm_Outputs
(N
);
217 if No
(Asm_Output_Variable
) then
219 ("??code statement with no outputs should usually be Volatile!", N
);
222 end Check_Code_Statement
;
224 ---------------------------------
225 -- Check_Infinite_Loop_Warning --
226 ---------------------------------
228 -- The case we look for is a while loop which tests a local variable, where
229 -- there is no obvious direct or possible indirect update of the variable
230 -- within the body of the loop.
232 procedure Check_Infinite_Loop_Warning
(Loop_Statement
: Node_Id
) is
233 Expression
: Node_Id
:= Empty
;
234 -- Set to WHILE or EXIT WHEN condition to be tested
236 Ref
: Node_Id
:= Empty
;
237 -- Reference in Expression to variable that might not be modified
238 -- in loop, indicating a possible infinite loop.
240 Var
: Entity_Id
:= Empty
;
241 -- Corresponding entity (entity of Ref)
243 Function_Call_Found
: Boolean := False;
244 -- True if Find_Var found a function call in the condition
246 procedure Find_Var
(N
: Node_Id
);
247 -- Inspect condition to see if it depends on a single entity reference.
248 -- If so, Ref is set to point to the reference node, and Var is set to
249 -- the referenced Entity.
251 function Has_Indirection
(T
: Entity_Id
) return Boolean;
252 -- If the controlling variable is an access type, or is a record type
253 -- with access components, assume that it is changed indirectly and
254 -- suppress the warning. As a concession to low-level programming, in
255 -- particular within Declib, we also suppress warnings on a record
256 -- type that contains components of type Address or Short_Address.
258 function Is_Suspicious_Function_Name
(E
: Entity_Id
) return Boolean;
259 -- Given an entity name, see if the name appears to have something to
260 -- do with I/O or network stuff, and if so, return True. Used to kill
261 -- some false positives on a heuristic basis that such functions will
262 -- likely have some strange side effect dependencies. A rather strange
263 -- test, but warning messages are in the heuristics business.
265 function Test_Ref
(N
: Node_Id
) return Traverse_Result
;
266 -- Test for reference to variable in question. Returns Abandon if
267 -- matching reference found. Used in instantiation of No_Ref_Found.
269 function No_Ref_Found
is new Traverse_Func
(Test_Ref
);
270 -- Function to traverse body of procedure. Returns Abandon if matching
277 procedure Find_Var
(N
: Node_Id
) is
279 -- Condition is a direct variable reference
281 if Is_Entity_Name
(N
) then
285 -- Case of condition is a comparison with compile time known value
287 elsif Nkind
(N
) in N_Op_Compare
then
288 if Compile_Time_Known_Value
(Right_Opnd
(N
)) then
289 Find_Var
(Left_Opnd
(N
));
291 elsif Compile_Time_Known_Value
(Left_Opnd
(N
)) then
292 Find_Var
(Right_Opnd
(N
));
294 -- Ignore any other comparison
300 -- If condition is a negation, check its operand
302 elsif Nkind
(N
) = N_Op_Not
then
303 Find_Var
(Right_Opnd
(N
));
305 -- Case of condition is function call
307 elsif Nkind
(N
) = N_Function_Call
then
309 Function_Call_Found
:= True;
311 -- Forget it if function name is not entity, who knows what
312 -- we might be calling?
314 if not Is_Entity_Name
(Name
(N
)) then
317 -- Forget it if function name is suspicious. A strange test
318 -- but warning generation is in the heuristics business.
320 elsif Is_Suspicious_Function_Name
(Entity
(Name
(N
))) then
323 -- Forget it if function is marked Volatile_Function
325 elsif Is_Volatile_Function
(Entity
(Name
(N
))) then
328 -- Forget it if warnings are suppressed on function entity
330 elsif Has_Warnings_Off
(Entity
(Name
(N
))) then
334 -- OK, see if we have one argument
337 PA
: constant List_Id
:= Parameter_Associations
(N
);
340 -- One argument, so check the argument
342 if Present
(PA
) and then List_Length
(PA
) = 1 then
343 if Nkind
(First
(PA
)) = N_Parameter_Association
then
344 Find_Var
(Explicit_Actual_Parameter
(First
(PA
)));
346 Find_Var
(First
(PA
));
356 -- Any other kind of node is not something we warn for
363 ---------------------
364 -- Has_Indirection --
365 ---------------------
367 function Has_Indirection
(T
: Entity_Id
) return Boolean is
372 if Is_Access_Type
(T
) then
375 elsif Is_Private_Type
(T
)
376 and then Present
(Full_View
(T
))
377 and then Is_Access_Type
(Full_View
(T
))
381 elsif Is_Record_Type
(T
) then
384 elsif Is_Private_Type
(T
)
385 and then Present
(Full_View
(T
))
386 and then Is_Record_Type
(Full_View
(T
))
388 Rec
:= Full_View
(T
);
393 Comp
:= First_Component
(Rec
);
394 while Present
(Comp
) loop
395 if Is_Access_Type
(Etype
(Comp
))
396 or else Is_Descendant_Of_Address
(Etype
(Comp
))
401 Next_Component
(Comp
);
407 ---------------------------------
408 -- Is_Suspicious_Function_Name --
409 ---------------------------------
411 function Is_Suspicious_Function_Name
(E
: Entity_Id
) return Boolean is
414 function Substring_Present
(S
: String) return Boolean;
415 -- Returns True if name buffer has given string delimited by non-
416 -- alphabetic characters or by end of string. S is lower case.
418 -----------------------
419 -- Substring_Present --
420 -----------------------
422 function Substring_Present
(S
: String) return Boolean is
423 Len
: constant Natural := S
'Length;
426 for J
in 1 .. Name_Len
- (Len
- 1) loop
427 if Name_Buffer
(J
.. J
+ (Len
- 1)) = S
428 and then (J
= 1 or else Name_Buffer
(J
- 1) not in 'a' .. 'z')
431 or else Name_Buffer
(J
+ Len
) not in 'a' .. 'z')
438 end Substring_Present
;
440 -- Start of processing for Is_Suspicious_Function_Name
444 while Present
(S
) and then S
/= Standard_Standard
loop
445 Get_Name_String
(Chars
(S
));
447 if Substring_Present
("io")
448 or else Substring_Present
("file")
449 or else Substring_Present
("network")
458 end Is_Suspicious_Function_Name
;
464 function Test_Ref
(N
: Node_Id
) return Traverse_Result
is
466 -- Waste of time to look at the expression we are testing
468 if N
= Expression
then
471 -- Direct reference to variable in question
473 elsif Is_Entity_Name
(N
)
474 and then Present
(Entity
(N
))
475 and then Entity
(N
) = Var
477 -- If this is an lvalue, then definitely abandon, since
478 -- this could be a direct modification of the variable.
480 if May_Be_Lvalue
(N
) then
484 -- If the condition contains a function call, we consider it may
485 -- be modified by side-effects from a procedure call. Otherwise,
486 -- we consider the condition may not be modified, although that
487 -- might happen if Variable is itself a by-reference parameter,
488 -- and the procedure called modifies the global object referred to
489 -- by Variable, but we actually prefer to issue a warning in this
490 -- odd case. Note that the case where the procedure called has
491 -- visibility over Variable is treated in another case below.
493 if Function_Call_Found
then
501 exit when P
= Loop_Statement
;
503 -- Abandon if at procedure call, or something strange is
504 -- going on (perhaps a node with no parent that should
505 -- have one but does not?) As always, for a warning we
506 -- prefer to just abandon the warning than get into the
507 -- business of complaining about the tree structure here.
510 or else Nkind
(P
) = N_Procedure_Call_Statement
518 -- Reference to variable renaming variable in question
520 elsif Is_Entity_Name
(N
)
521 and then Present
(Entity
(N
))
522 and then Ekind
(Entity
(N
)) = E_Variable
523 and then Present
(Renamed_Object
(Entity
(N
)))
524 and then Is_Entity_Name
(Renamed_Object
(Entity
(N
)))
525 and then Entity
(Renamed_Object
(Entity
(N
))) = Var
526 and then May_Be_Lvalue
(N
)
530 -- Call to subprogram
532 elsif Nkind
(N
) in N_Subprogram_Call
then
534 -- If subprogram is within the scope of the entity we are dealing
535 -- with as the loop variable, then it could modify this parameter,
536 -- so we abandon in this case. In the case of a subprogram that is
537 -- not an entity we also abandon. The check for no entity being
538 -- present is a defense against previous errors.
540 if not Is_Entity_Name
(Name
(N
))
541 or else No
(Entity
(Name
(N
)))
542 or else Scope_Within
(Entity
(Name
(N
)), Scope
(Var
))
547 -- If any of the arguments are of type access to subprogram, then
548 -- we may have funny side effects, so no warning in this case.
553 Actual
:= First_Actual
(N
);
554 while Present
(Actual
) loop
555 if Is_Access_Subprogram_Type
(Etype
(Actual
)) then
558 Next_Actual
(Actual
);
563 -- Declaration of the variable in question
565 elsif Nkind
(N
) = N_Object_Declaration
566 and then Defining_Identifier
(N
) = Var
571 -- All OK, continue scan
576 -- Start of processing for Check_Infinite_Loop_Warning
579 -- Skip processing if debug flag gnatd.w is set
581 if Debug_Flag_Dot_W
then
585 -- Deal with Iteration scheme present
588 Iter
: constant Node_Id
:= Iteration_Scheme
(Loop_Statement
);
591 if Present
(Iter
) then
595 if Present
(Condition
(Iter
)) then
597 -- Skip processing for while iteration with conditions actions,
598 -- since they make it too complicated to get the warning right.
600 if Present
(Condition_Actions
(Iter
)) then
604 -- Capture WHILE condition
606 Expression
:= Condition
(Iter
);
608 -- For iteration, do not process, since loop will always terminate
610 elsif Present
(Loop_Parameter_Specification
(Iter
)) then
616 -- Check chain of EXIT statements, we only process loops that have a
617 -- single exit condition (either a single EXIT WHEN statement, or a
618 -- WHILE loop not containing any EXIT WHEN statements).
621 Ident
: constant Node_Id
:= Identifier
(Loop_Statement
);
625 -- If we don't have a proper chain set, ignore call entirely. This
626 -- happens because of previous errors.
628 if No
(Entity
(Ident
))
629 or else Ekind
(Entity
(Ident
)) /= E_Loop
631 Check_Error_Detected
;
635 -- Otherwise prepare to scan list of EXIT statements
637 Exit_Stmt
:= First_Exit_Statement
(Entity
(Ident
));
638 while Present
(Exit_Stmt
) loop
640 -- Check for EXIT WHEN
642 if Present
(Condition
(Exit_Stmt
)) then
644 -- Quit processing if EXIT WHEN in WHILE loop, or more than
645 -- one EXIT WHEN statement present in the loop.
647 if Present
(Expression
) then
650 -- Otherwise capture condition from EXIT WHEN statement
653 Expression
:= Condition
(Exit_Stmt
);
656 -- If an unconditional exit statement is the last statement in the
657 -- loop, assume that no warning is needed, without any attempt at
658 -- checking whether the exit is reachable.
660 elsif Exit_Stmt
= Last
(Statements
(Loop_Statement
)) then
664 Exit_Stmt
:= Next_Exit_Statement
(Exit_Stmt
);
668 -- Return if no condition to test
670 if No
(Expression
) then
674 -- Initial conditions met, see if condition is of right form
676 Find_Var
(Expression
);
678 -- Nothing to do if local variable from source not found. If it's a
679 -- renaming, it is probably renaming something too complicated to deal
683 or else Ekind
(Var
) /= E_Variable
684 or else Is_Library_Level_Entity
(Var
)
685 or else not Comes_From_Source
(Var
)
686 or else Nkind
(Parent
(Var
)) = N_Object_Renaming_Declaration
690 -- Nothing to do if there is some indirection involved (assume that the
691 -- designated variable might be modified in some way we don't see).
692 -- However, if no function call was found, then we don't care about
693 -- indirections, because the condition must be something like "while X
694 -- /= null loop", so we don't care if X.all is modified in the loop.
696 elsif Function_Call_Found
and then Has_Indirection
(Etype
(Var
)) then
699 -- Same sort of thing for volatile variable, might be modified by
700 -- some other task or by the operating system in some way.
702 elsif Is_Volatile
(Var
) then
706 -- Filter out case of original statement sequence starting with delay.
707 -- We assume this is a multi-tasking program and that the condition
708 -- is affected by other threads (some kind of busy wait).
711 Fstm
: constant Node_Id
:=
712 Original_Node
(First
(Statements
(Loop_Statement
)));
714 if Nkind
(Fstm
) = N_Delay_Relative_Statement
715 or else Nkind
(Fstm
) = N_Delay_Until_Statement
721 -- We have a variable reference of the right form, now we scan the loop
722 -- body to see if it looks like it might not be modified
724 if No_Ref_Found
(Loop_Statement
) = OK
then
726 ("??variable& is not modified in loop body!", Ref
, Var
);
728 ("\??possible infinite loop!", Ref
);
730 end Check_Infinite_Loop_Warning
;
732 ----------------------------
733 -- Check_Low_Bound_Tested --
734 ----------------------------
736 procedure Check_Low_Bound_Tested
(Expr
: Node_Id
) is
737 procedure Check_Low_Bound_Tested_For
(Opnd
: Node_Id
);
738 -- Determine whether operand Opnd denotes attribute 'First whose prefix
739 -- is a formal parameter. If this is the case, mark the entity of the
740 -- prefix as having its low bound tested.
742 --------------------------------
743 -- Check_Low_Bound_Tested_For --
744 --------------------------------
746 procedure Check_Low_Bound_Tested_For
(Opnd
: Node_Id
) is
748 if Nkind
(Opnd
) = N_Attribute_Reference
749 and then Attribute_Name
(Opnd
) = Name_First
750 and then Is_Entity_Name
(Prefix
(Opnd
))
751 and then Present
(Entity
(Prefix
(Opnd
)))
752 and then Is_Formal
(Entity
(Prefix
(Opnd
)))
754 Set_Low_Bound_Tested
(Entity
(Prefix
(Opnd
)));
756 end Check_Low_Bound_Tested_For
;
758 -- Start of processing for Check_Low_Bound_Tested
761 if Comes_From_Source
(Expr
) then
762 Check_Low_Bound_Tested_For
(Left_Opnd
(Expr
));
763 Check_Low_Bound_Tested_For
(Right_Opnd
(Expr
));
765 end Check_Low_Bound_Tested
;
767 ----------------------
768 -- Check_References --
769 ----------------------
771 procedure Check_References
(E
: Entity_Id
; Anod
: Node_Id
:= Empty
) is
778 Accept_Statement
: Node_Id
) return Entity_Id
;
779 -- For an entry formal entity from an entry declaration, find the
780 -- corresponding body formal from the given accept statement.
782 procedure May_Need_Initialized_Actual
(Ent
: Entity_Id
);
783 -- If an entity of a generic type has default initialization, then the
784 -- corresponding actual type should be fully initialized, or else there
785 -- will be uninitialized components in the instantiation, that might go
786 -- unreported. This routine marks the type of the uninitialized variable
787 -- appropriately to allow the compiler to emit an appropriate warning
788 -- in the instance. In a sense, the use of a type that requires full
789 -- initialization is a weak part of the generic contract.
791 function Missing_Subunits
return Boolean;
792 -- We suppress warnings when there are missing subunits, because this
793 -- may generate too many false positives: entities in a parent may only
794 -- be referenced in one of the subunits. We make an exception for
795 -- subunits that contain no other stubs.
797 procedure Output_Reference_Error
(M
: String);
798 -- Used to output an error message. Deals with posting the error on the
799 -- body formal in the accept case.
801 function Publicly_Referenceable
(Ent
: Entity_Id
) return Boolean;
802 -- This is true if the entity in question is potentially referenceable
803 -- from another unit. This is true for entities in packages that are at
804 -- the library level.
806 function Warnings_Off_E1
return Boolean;
807 -- Return True if Warnings_Off is set for E1, or for its Etype (E1T),
808 -- or for the base type of E1T.
816 Accept_Statement
: Node_Id
) return Entity_Id
818 Body_Param
: Node_Id
;
822 -- Loop to find matching parameter in accept statement
824 Body_Param
:= First
(Parameter_Specifications
(Accept_Statement
));
825 while Present
(Body_Param
) loop
826 Body_E
:= Defining_Identifier
(Body_Param
);
828 if Chars
(Body_E
) = Chars
(E
) then
835 -- Should never fall through, should always find a match
840 ---------------------------------
841 -- May_Need_Initialized_Actual --
842 ---------------------------------
844 procedure May_Need_Initialized_Actual
(Ent
: Entity_Id
) is
845 T
: constant Entity_Id
:= Etype
(Ent
);
846 Par
: constant Node_Id
:= Parent
(T
);
849 if not Is_Generic_Type
(T
) then
852 elsif (Nkind
(Par
)) = N_Private_Extension_Declaration
then
854 -- We only indicate the first such variable in the generic.
856 if No
(Uninitialized_Variable
(Par
)) then
857 Set_Uninitialized_Variable
(Par
, Ent
);
860 elsif (Nkind
(Par
)) = N_Formal_Type_Declaration
861 and then Nkind
(Formal_Type_Definition
(Par
)) =
862 N_Formal_Private_Type_Definition
864 if No
(Uninitialized_Variable
(Formal_Type_Definition
(Par
))) then
865 Set_Uninitialized_Variable
(Formal_Type_Definition
(Par
), Ent
);
868 end May_Need_Initialized_Actual
;
870 ----------------------
871 -- Missing_Subunits --
872 ----------------------
874 function Missing_Subunits
return Boolean is
878 if not Unloaded_Subunits
then
880 -- Normal compilation, all subunits are present
884 elsif E
/= Main_Unit_Entity
then
886 -- No warnings on a stub that is not the main unit
890 elsif Nkind
(Unit_Declaration_Node
(E
)) in N_Proper_Body
then
891 D
:= First
(Declarations
(Unit_Declaration_Node
(E
)));
892 while Present
(D
) loop
894 -- No warnings if the proper body contains nested stubs
896 if Nkind
(D
) in N_Body_Stub
then
906 -- Missing stubs elsewhere
910 end Missing_Subunits
;
912 ----------------------------
913 -- Output_Reference_Error --
914 ----------------------------
916 procedure Output_Reference_Error
(M
: String) is
918 -- Never issue messages for internal names or renamings
920 if Is_Internal_Name
(Chars
(E1
))
921 or else Nkind
(Parent
(E1
)) = N_Object_Renaming_Declaration
926 -- Don't output message for IN OUT formal unless we have the warning
927 -- flag specifically set. It is a bit odd to distinguish IN OUT
928 -- formals from other cases. This distinction is historical in
929 -- nature. Warnings for IN OUT formals were added fairly late.
931 if Ekind
(E1
) = E_In_Out_Parameter
932 and then not Check_Unreferenced_Formals
937 -- Other than accept case, post error on defining identifier
942 -- Accept case, find body formal to post the message
945 Error_Msg_NE
(M
, Body_Formal
(E1
, Accept_Statement
=> Anod
), E1
);
948 end Output_Reference_Error
;
950 ----------------------------
951 -- Publicly_Referenceable --
952 ----------------------------
954 function Publicly_Referenceable
(Ent
: Entity_Id
) return Boolean is
959 -- A formal parameter is never referenceable outside the body of its
960 -- subprogram or entry.
962 if Is_Formal
(Ent
) then
966 -- Examine parents to look for a library level package spec. But if
967 -- we find a body or block or other similar construct along the way,
968 -- we cannot be referenced.
975 -- If we get to top of tree, then publicly referenceable
980 -- If we reach a generic package declaration, then always
981 -- consider this referenceable, since any instantiation will
982 -- have access to the entities in the generic package. Note
983 -- that the package itself may not be instantiated, but then
984 -- we will get a warning for the package entity.
986 -- Note that generic formal parameters are themselves not
987 -- publicly referenceable in an instance, and warnings on them
990 when N_Generic_Package_Declaration
=>
992 not Is_List_Member
(Prev
)
993 or else List_Containing
(Prev
) /=
994 Generic_Formal_Declarations
(P
);
996 -- Similarly, the generic formals of a generic subprogram are
999 when N_Generic_Subprogram_Declaration
=>
1000 if Is_List_Member
(Prev
)
1001 and then List_Containing
(Prev
) =
1002 Generic_Formal_Declarations
(P
)
1009 -- If we reach a subprogram body, entity is not referenceable
1010 -- unless it is the defining entity of the body. This will
1011 -- happen, e.g. when a function is an attribute renaming that
1012 -- is rewritten as a body.
1014 when N_Subprogram_Body
=>
1015 if Ent
/= Defining_Entity
(P
) then
1021 -- If we reach any other body, definitely not referenceable
1023 when N_Block_Statement
1032 -- For all other cases, keep looking up tree
1039 end Publicly_Referenceable
;
1041 ---------------------
1042 -- Warnings_Off_E1 --
1043 ---------------------
1045 function Warnings_Off_E1
return Boolean is
1047 return Has_Warnings_Off
(E1T
)
1048 or else Has_Warnings_Off
(Base_Type
(E1T
))
1049 or else Warnings_Off_Check_Spec
(E1
);
1050 end Warnings_Off_E1
;
1052 -- Start of processing for Check_References
1055 Process_Deferred_References
;
1057 -- No messages if warnings are suppressed, or if we have detected any
1058 -- real errors so far (this last check avoids junk messages resulting
1059 -- from errors, e.g. a subunit that is not loaded).
1061 if Warning_Mode
= Suppress
or else Serious_Errors_Detected
/= 0 then
1065 -- We also skip the messages if any subunits were not loaded (see
1066 -- comment in Sem_Ch10 to understand how this is set, and why it is
1067 -- necessary to suppress the warnings in this case).
1069 if Missing_Subunits
then
1073 -- Otherwise loop through entities, looking for suspicious stuff
1075 E1
:= First_Entity
(E
);
1076 while Present
(E1
) loop
1079 -- We are only interested in source entities. We also don't issue
1080 -- warnings within instances, since the proper place for such
1081 -- warnings is on the template when it is compiled, and we don't
1082 -- issue warnings for variables with names like Junk, Discard etc.
1084 if Comes_From_Source
(E1
)
1085 and then Instantiation_Location
(Sloc
(E1
)) = No_Location
1087 -- We are interested in variables and out/in-out parameters, but
1088 -- we exclude protected types, too complicated to worry about.
1090 if Ekind
(E1
) = E_Variable
1092 (Ekind_In
(E1
, E_Out_Parameter
, E_In_Out_Parameter
)
1093 and then not Is_Protected_Type
(Current_Scope
))
1095 -- If the formal has a class-wide type, retrieve its type
1096 -- because checks below depend on its private nature.
1098 if Is_Class_Wide_Type
(E1T
) then
1102 -- Case of an unassigned variable
1104 -- First gather any Unset_Reference indication for E1. In the
1105 -- case of a parameter, it is the Spec_Entity that is relevant.
1107 if Ekind
(E1
) = E_Out_Parameter
1108 and then Present
(Spec_Entity
(E1
))
1110 UR
:= Unset_Reference
(Spec_Entity
(E1
));
1112 UR
:= Unset_Reference
(E1
);
1115 -- Special processing for access types
1117 if Present
(UR
) and then Is_Access_Type
(E1T
) then
1119 -- For access types, the only time we made a UR entry was
1120 -- for a dereference, and so we post the appropriate warning
1121 -- here (note that the dereference may not be explicit in
1122 -- the source, for example in the case of a dispatching call
1123 -- with an anonymous access controlling formal, or of an
1124 -- assignment of a pointer involving discriminant check on
1125 -- the designated object).
1127 if not Warnings_Off_E1
then
1128 Error_Msg_NE
("??& may be null!", UR
, E1
);
1133 -- Case of variable that could be a constant. Note that we
1134 -- never signal such messages for generic package entities,
1135 -- since a given instance could have modifications outside
1138 -- Note that we used to check Address_Taken here, but we don't
1139 -- want to do that since it can be set for non-source cases,
1140 -- e.g. the Unrestricted_Access from a valid attribute, and
1141 -- the wanted effect is included in Never_Set_In_Source.
1143 elsif Warn_On_Constant
1144 and then (Ekind
(E1
) = E_Variable
1145 and then Has_Initial_Value
(E1
))
1146 and then Never_Set_In_Source_Check_Spec
(E1
)
1147 and then not Generic_Package_Spec_Entity
(E1
)
1149 -- A special case, if this variable is volatile and not
1150 -- imported, it is not helpful to tell the programmer
1151 -- to mark the variable as constant, since this would be
1152 -- illegal by virtue of RM C.6(13). Instead we suggest
1153 -- using pragma Export (can't be Import because of the
1156 if (Is_Volatile
(E1
) or else Has_Volatile_Components
(E1
))
1157 and then not Is_Imported
(E1
)
1160 ("?k?& is not modified, consider pragma Export for "
1161 & "volatile variable!", E1
);
1163 -- Another special case, Exception_Occurrence, this catches
1164 -- the case of exception choice (and a bit more too, but not
1165 -- worth doing more investigation here).
1167 elsif Is_RTE
(E1T
, RE_Exception_Occurrence
) then
1170 -- Here we give the warning if referenced and no pragma
1171 -- Unreferenced or Unmodified is present.
1176 if Ekind
(E1
) = E_Variable
then
1177 if Referenced_Check_Spec
(E1
)
1178 and then not Has_Pragma_Unreferenced_Check_Spec
(E1
)
1179 and then not Has_Pragma_Unmodified_Check_Spec
(E1
)
1181 if not Warnings_Off_E1
1182 and then not Has_Junk_Name
(E1
)
1184 Error_Msg_N
-- CODEFIX
1185 ("?k?& is not modified, "
1186 & "could be declared constant!",
1193 -- Other cases of a variable or parameter never set in source
1195 elsif Never_Set_In_Source_Check_Spec
(E1
)
1197 -- No warning if warning for this case turned off
1199 and then Warn_On_No_Value_Assigned
1201 -- No warning if address taken somewhere
1203 and then not Address_Taken
(E1
)
1205 -- No warning if explicit initial value
1207 and then not Has_Initial_Value
(E1
)
1209 -- No warning for generic package spec entities, since we
1210 -- might set them in a child unit or something like that
1212 and then not Generic_Package_Spec_Entity
(E1
)
1214 -- No warning if fully initialized type, except that for
1215 -- this purpose we do not consider access types to qualify
1216 -- as fully initialized types (relying on an access type
1217 -- variable being null when it is never set is a bit odd).
1219 -- Also we generate warning for an out parameter that is
1220 -- never referenced, since again it seems odd to rely on
1221 -- default initialization to set an out parameter value.
1223 and then (Is_Access_Type
(E1T
)
1224 or else Ekind
(E1
) = E_Out_Parameter
1225 or else not Is_Fully_Initialized_Type
(E1T
))
1227 -- Do not output complaint about never being assigned a
1228 -- value if a pragma Unmodified applies to the variable
1229 -- we are examining, or if it is a parameter, if there is
1230 -- a pragma Unreferenced for the corresponding spec, or
1231 -- if the type is marked as having unreferenced objects.
1232 -- The last is a little peculiar, but better too few than
1233 -- too many warnings in this situation.
1235 if Has_Pragma_Unreferenced_Objects
(E1T
)
1236 or else Has_Pragma_Unmodified_Check_Spec
(E1
)
1240 -- IN OUT parameter case where parameter is referenced. We
1241 -- separate this out, since this is the case where we delay
1242 -- output of the warning until more information is available
1243 -- (about use in an instantiation or address being taken).
1245 elsif Ekind
(E1
) = E_In_Out_Parameter
1246 and then Referenced_Check_Spec
(E1
)
1248 -- Suppress warning if private type, and the procedure
1249 -- has a separate declaration in a different unit. This
1250 -- is the case where the client of a package sees only
1251 -- the private type, and it may be quite reasonable
1252 -- for the logical view to be IN OUT, even if the
1253 -- implementation ends up using access types or some
1254 -- other method to achieve the local effect of a
1255 -- modification. On the other hand if the spec and body
1256 -- are in the same unit, we are in the package body and
1257 -- there we have less excuse for a junk IN OUT parameter.
1259 if Has_Private_Declaration
(E1T
)
1260 and then Present
(Spec_Entity
(E1
))
1261 and then not In_Same_Source_Unit
(E1
, Spec_Entity
(E1
))
1265 -- Suppress warning for any parameter of a dispatching
1266 -- operation, since it is quite reasonable to have an
1267 -- operation that is overridden, and for some subclasses
1268 -- needs the formal to be IN OUT and for others happens
1269 -- not to assign it.
1271 elsif Is_Dispatching_Operation
1272 (Scope
(Goto_Spec_Entity
(E1
)))
1276 -- Suppress warning if composite type contains any access
1277 -- component, since the logical effect of modifying a
1278 -- parameter may be achieved by modifying a referenced
1281 elsif Is_Composite_Type
(E1T
)
1282 and then Has_Access_Values
(E1T
)
1286 -- Suppress warning on formals of an entry body. All
1287 -- references are attached to the formal in the entry
1288 -- declaration, which are marked Is_Entry_Formal.
1290 elsif Ekind
(Scope
(E1
)) = E_Entry
1291 and then not Is_Entry_Formal
(E1
)
1295 -- OK, looks like warning for an IN OUT parameter that
1296 -- could be IN makes sense, but we delay the output of
1297 -- the warning, pending possibly finding out later on
1298 -- that the associated subprogram is used as a generic
1299 -- actual, or its address/access is taken. In these two
1300 -- cases, we suppress the warning because the context may
1301 -- force use of IN OUT, even if in this particular case
1302 -- the formal is not modified.
1305 -- Suppress the warnings for a junk name
1307 if not Has_Junk_Name
(E1
) then
1308 In_Out_Warnings
.Append
(E1
);
1312 -- Other cases of formals
1314 elsif Is_Formal
(E1
) then
1315 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1316 if Referenced_Check_Spec
(E1
) then
1317 if not Has_Pragma_Unmodified_Check_Spec
(E1
)
1318 and then not Warnings_Off_E1
1319 and then not Has_Junk_Name
(E1
)
1321 Output_Reference_Error
1322 ("?f?formal parameter& is read but "
1323 & "never assigned!");
1326 elsif not Has_Pragma_Unreferenced_Check_Spec
(E1
)
1327 and then not Warnings_Off_E1
1328 and then not Has_Junk_Name
(E1
)
1330 Output_Reference_Error
1331 ("?f?formal parameter& is not referenced!");
1338 if Referenced
(E1
) then
1339 if not Has_Unmodified
(E1
)
1340 and then not Warnings_Off_E1
1341 and then not Has_Junk_Name
(E1
)
1343 Output_Reference_Error
1344 ("?v?variable& is read but never assigned!");
1345 May_Need_Initialized_Actual
(E1
);
1348 elsif not Has_Unreferenced
(E1
)
1349 and then not Warnings_Off_E1
1350 and then not Has_Junk_Name
(E1
)
1352 Output_Reference_Error
-- CODEFIX
1353 ("?v?variable& is never read and never assigned!");
1356 -- Deal with special case where this variable is hidden
1357 -- by a loop variable.
1359 if Ekind
(E1
) = E_Variable
1360 and then Present
(Hiding_Loop_Variable
(E1
))
1361 and then not Warnings_Off_E1
1364 ("?v?for loop implicitly declares loop variable!",
1365 Hiding_Loop_Variable
(E1
));
1367 Error_Msg_Sloc
:= Sloc
(E1
);
1369 ("\?v?declaration hides & declared#!",
1370 Hiding_Loop_Variable
(E1
));
1377 -- Check for unset reference
1379 if Warn_On_No_Value_Assigned
and then Present
(UR
) then
1381 -- For other than access type, go back to original node to
1382 -- deal with case where original unset reference has been
1383 -- rewritten during expansion.
1385 -- In some cases, the original node may be a type
1386 -- conversion, a qualification or an attribute reference and
1387 -- in this case we want the object entity inside. Same for
1388 -- an expression with actions.
1390 UR
:= Original_Node
(UR
);
1392 if Nkind_In
(UR
, N_Expression_With_Actions
,
1393 N_Qualified_Expression
,
1396 UR
:= Expression
(UR
);
1398 elsif Nkind
(UR
) = N_Attribute_Reference
then
1406 -- Don't issue warning if appearing inside Initial_Condition
1407 -- pragma or aspect, since that expression is not evaluated
1408 -- at the point where it occurs in the source.
1410 if In_Pragma_Expression
(UR
, Name_Initial_Condition
) then
1414 -- Here we issue the warning, all checks completed
1416 -- If we have a return statement, this was a case of an OUT
1417 -- parameter not being set at the time of the return. (Note:
1418 -- it can't be N_Extended_Return_Statement, because those
1419 -- are only for functions, and functions do not allow OUT
1422 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1423 if Nkind
(UR
) = N_Simple_Return_Statement
1424 and then not Has_Pragma_Unmodified_Check_Spec
(E1
)
1426 if not Warnings_Off_E1
1427 and then not Has_Junk_Name
(E1
)
1430 ("?v?OUT parameter& not set before return",
1434 -- If the unset reference is a selected component
1435 -- prefix from source, mention the component as well.
1436 -- If the selected component comes from expansion, all
1437 -- we know is that the entity is not fully initialized
1438 -- at the point of the reference. Locate a random
1439 -- uninitialized component to get a better message.
1441 elsif Nkind
(Parent
(UR
)) = N_Selected_Component
then
1442 Error_Msg_Node_2
:= Selector_Name
(Parent
(UR
));
1444 if not Comes_From_Source
(Parent
(UR
)) then
1449 Comp
:= First_Entity
(E1T
);
1450 while Present
(Comp
) loop
1451 if Ekind
(Comp
) = E_Component
1452 and then Nkind
(Parent
(Comp
)) =
1453 N_Component_Declaration
1454 and then No
(Expression
(Parent
(Comp
)))
1456 Error_Msg_Node_2
:= Comp
;
1465 -- Issue proper warning. This is a case of referencing
1466 -- a variable before it has been explicitly assigned.
1467 -- For access types, UR was only set for dereferences,
1468 -- so the issue is that the value may be null.
1470 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
1471 if not Warnings_Off_E1
then
1472 if Is_Access_Type
(Etype
(Parent
(UR
))) then
1473 Error_Msg_N
("??`&.&` may be null!", UR
);
1476 ("??`&.&` may be referenced before "
1477 & "it has a value!", UR
);
1482 -- All other cases of unset reference active
1484 elsif not Warnings_Off_E1
then
1486 ("??& may be referenced before it has a value!", UR
);
1495 -- Then check for unreferenced entities. Note that we are only
1496 -- interested in entities whose Referenced flag is not set.
1498 if not Referenced_Check_Spec
(E1
)
1500 -- If Referenced_As_LHS is set, then that's still interesting
1501 -- (potential "assigned but never read" case), but not if we
1502 -- have pragma Unreferenced, which cancels this warning.
1504 and then (not Referenced_As_LHS_Check_Spec
(E1
)
1505 or else not Has_Unreferenced
(E1
))
1507 -- Check that warnings on unreferenced entities are enabled
1510 ((Check_Unreferenced
and then not Is_Formal
(E1
))
1512 -- Case of warning on unreferenced formal
1514 or else (Check_Unreferenced_Formals
and then Is_Formal
(E1
))
1516 -- Case of warning on unread variables modified by an
1517 -- assignment, or an OUT parameter if it is the only one.
1519 or else (Warn_On_Modified_Unread
1520 and then Referenced_As_LHS_Check_Spec
(E1
))
1522 -- Case of warning on any unread OUT parameter (note such
1523 -- indications are only set if the appropriate warning
1524 -- options were set, so no need to recheck here.)
1526 or else Referenced_As_Out_Parameter_Check_Spec
(E1
))
1528 -- All other entities, including local packages that cannot be
1529 -- referenced from elsewhere, including those declared within a
1532 and then (Is_Object
(E1
)
1533 or else Is_Type
(E1
)
1534 or else Ekind
(E1
) = E_Label
1535 or else Ekind_In
(E1
, E_Exception
,
1538 or else Is_Overloadable
(E1
)
1540 -- Package case, if the main unit is a package spec
1541 -- or generic package spec, then there may be a
1542 -- corresponding body that references this package
1543 -- in some other file. Otherwise we can be sure
1544 -- that there is no other reference.
1547 (Ekind
(E1
) = E_Package
1549 not Is_Package_Or_Generic_Package
1550 (Cunit_Entity
(Current_Sem_Unit
))))
1552 -- Exclude instantiations, since there is no reason why every
1553 -- entity in an instantiation should be referenced.
1555 and then Instantiation_Location
(Sloc
(E1
)) = No_Location
1557 -- Exclude formal parameters from bodies if the corresponding
1558 -- spec entity has been referenced in the case where there is
1561 and then not (Is_Formal
(E1
)
1562 and then Ekind
(Scope
(E1
)) = E_Subprogram_Body
1563 and then Present
(Spec_Entity
(E1
))
1564 and then Referenced
(Spec_Entity
(E1
)))
1566 -- Consider private type referenced if full view is referenced.
1567 -- If there is not full view, this is a generic type on which
1568 -- warnings are also useful.
1571 not (Is_Private_Type
(E1
)
1572 and then Present
(Full_View
(E1
))
1573 and then Referenced
(Full_View
(E1
)))
1575 -- Don't worry about full view, only about private type
1577 and then not Has_Private_Declaration
(E1
)
1579 -- Eliminate dispatching operations from consideration, we
1580 -- cannot tell if these are referenced or not in any easy
1581 -- manner (note this also catches Adjust/Finalize/Initialize).
1583 and then not Is_Dispatching_Operation
(E1
)
1585 -- Check entity that can be publicly referenced (we do not give
1586 -- messages for such entities, since there could be other
1587 -- units, not involved in this compilation, that contain
1588 -- relevant references.
1590 and then not Publicly_Referenceable
(E1
)
1592 -- Class wide types are marked as source entities, but they are
1593 -- not really source entities, and are always created, so we do
1594 -- not care if they are not referenced.
1596 and then Ekind
(E1
) /= E_Class_Wide_Type
1598 -- Objects other than parameters of task types are allowed to
1599 -- be non-referenced, since they start up tasks.
1601 and then ((Ekind
(E1
) /= E_Variable
1602 and then Ekind
(E1
) /= E_Constant
1603 and then Ekind
(E1
) /= E_Component
)
1604 or else not Is_Task_Type
(E1T
))
1606 -- For subunits, only place warnings on the main unit itself,
1607 -- since parent units are not completely compiled.
1609 and then (Nkind
(Unit
(Cunit
(Main_Unit
))) /= N_Subunit
1610 or else Get_Source_Unit
(E1
) = Main_Unit
)
1612 -- No warning on a return object, because these are often
1613 -- created with a single expression and an implicit return.
1614 -- If the object is a variable there will be a warning
1615 -- indicating that it could be declared constant.
1618 (Ekind
(E1
) = E_Constant
and then Is_Return_Object
(E1
))
1620 -- Suppress warnings in internal units if not in -gnatg mode
1621 -- (these would be junk warnings for an applications program,
1622 -- since they refer to problems in internal units).
1624 if GNAT_Mode
or else not In_Internal_Unit
(E1
) then
1625 -- We do not immediately flag the error. This is because we
1626 -- have not expanded generic bodies yet, and they may have
1627 -- the missing reference. So instead we park the entity on a
1628 -- list, for later processing. However for the case of an
1629 -- accept statement we want to output messages now, since
1630 -- we know we already have all information at hand, and we
1631 -- also want to have separate warnings for each accept
1632 -- statement for the same entry.
1634 if Present
(Anod
) then
1635 pragma Assert
(Is_Formal
(E1
));
1637 -- The unreferenced entity is E1, but post the warning
1638 -- on the body entity for this accept statement.
1640 if not Warnings_Off_E1
then
1641 Warn_On_Unreferenced_Entity
1642 (E1
, Body_Formal
(E1
, Accept_Statement
=> Anod
));
1645 elsif not Warnings_Off_E1
1646 and then not Has_Junk_Name
(E1
)
1648 Unreferenced_Entities
.Append
(E1
);
1652 -- Generic units are referenced in the generic body, but if they
1653 -- are not public and never instantiated we want to force a
1654 -- warning on them. We treat them as redundant constructs to
1657 elsif Is_Generic_Subprogram
(E1
)
1658 and then not Is_Instantiated
(E1
)
1659 and then not Publicly_Referenceable
(E1
)
1660 and then Instantiation_Depth
(Sloc
(E1
)) = 0
1661 and then Warn_On_Redundant_Constructs
1663 if not Warnings_Off_E1
and then not Has_Junk_Name
(E1
) then
1664 Unreferenced_Entities
.Append
(E1
);
1666 -- Force warning on entity
1668 Set_Referenced
(E1
, False);
1673 -- Recurse into nested package or block. Do not recurse into a formal
1674 -- package, because the corresponding body is not analyzed.
1677 if (Is_Package_Or_Generic_Package
(E1
)
1678 and then Nkind
(Parent
(E1
)) = N_Package_Specification
1680 Nkind
(Original_Node
(Unit_Declaration_Node
(E1
))) /=
1681 N_Formal_Package_Declaration
)
1683 or else Ekind
(E1
) = E_Block
1685 Check_References
(E1
);
1690 end Check_References
;
1692 ---------------------------
1693 -- Check_Unset_Reference --
1694 ---------------------------
1696 procedure Check_Unset_Reference
(N
: Node_Id
) is
1697 Typ
: constant Entity_Id
:= Etype
(N
);
1699 function Is_OK_Fully_Initialized
return Boolean;
1700 -- This function returns true if the given node N is fully initialized
1701 -- so that the reference is safe as far as this routine is concerned.
1702 -- Safe generally means that the type of N is a fully initialized type.
1703 -- The one special case is that for access types, which are always fully
1704 -- initialized, we don't consider a dereference OK since it will surely
1705 -- be dereferencing a null value, which won't do.
1707 function Prefix_Has_Dereference
(Pref
: Node_Id
) return Boolean;
1708 -- Used to test indexed or selected component or slice to see if the
1709 -- evaluation of the prefix depends on a dereference, and if so, returns
1710 -- True, in which case we always check the prefix, even if we know that
1711 -- the referenced component is initialized. Pref is the prefix to test.
1713 -----------------------------
1714 -- Is_OK_Fully_Initialized --
1715 -----------------------------
1717 function Is_OK_Fully_Initialized
return Boolean is
1721 if Is_Access_Type
(Typ
) and then Is_Dereferenced
(N
) then
1724 -- A type subject to pragma Default_Initial_Condition is fully
1725 -- default initialized when the pragma appears with a non-null
1726 -- argument (SPARK RM 3.1 and SPARK RM 7.3.3).
1728 elsif Has_DIC
(Typ
) then
1729 Prag
:= Get_Pragma
(Typ
, Pragma_Default_Initial_Condition
);
1730 pragma Assert
(Present
(Prag
));
1732 return Is_Verifiable_DIC_Pragma
(Prag
);
1735 return Is_Fully_Initialized_Type
(Typ
);
1737 end Is_OK_Fully_Initialized
;
1739 ----------------------------
1740 -- Prefix_Has_Dereference --
1741 ----------------------------
1743 function Prefix_Has_Dereference
(Pref
: Node_Id
) return Boolean is
1745 -- If prefix is of an access type, it certainly needs a dereference
1747 if Is_Access_Type
(Etype
(Pref
)) then
1750 -- If prefix is explicit dereference, that's a dereference for sure
1752 elsif Nkind
(Pref
) = N_Explicit_Dereference
then
1755 -- If prefix is itself a component reference or slice check prefix
1757 elsif Nkind
(Pref
) = N_Slice
1758 or else Nkind
(Pref
) = N_Indexed_Component
1759 or else Nkind
(Pref
) = N_Selected_Component
1761 return Prefix_Has_Dereference
(Prefix
(Pref
));
1763 -- All other cases do not involve a dereference
1768 end Prefix_Has_Dereference
;
1770 -- Start of processing for Check_Unset_Reference
1773 -- Nothing to do if warnings suppressed
1775 if Warning_Mode
= Suppress
then
1779 -- Nothing to do for numeric or string literal. Do this test early to
1780 -- save time in a common case (it does not matter that we do not include
1781 -- character literal here, since that will be caught later on in the
1782 -- when others branch of the case statement).
1784 if Nkind
(N
) in N_Numeric_Or_String_Literal
then
1788 -- Ignore reference unless it comes from source. Almost always if we
1789 -- have a reference from generated code, it is bogus (e.g. calls to init
1790 -- procs to set default discriminant values).
1792 if not Comes_From_Source
(N
) then
1796 -- Otherwise see what kind of node we have. If the entity already has an
1797 -- unset reference, it is not necessarily the earliest in the text,
1798 -- because resolution of the prefix of selected components is completed
1799 -- before the resolution of the selected component itself. As a result,
1800 -- given (R /= null and then R.X > 0), the occurrences of R are examined
1801 -- in right-to-left order. If there is already an unset reference, we
1802 -- check whether N is earlier before proceeding.
1806 -- For identifier or expanded name, examine the entity involved
1808 when N_Expanded_Name
1812 E
: constant Entity_Id
:= Entity
(N
);
1815 if Ekind_In
(E
, E_Variable
, E_Out_Parameter
)
1816 and then Never_Set_In_Source_Check_Spec
(E
)
1817 and then not Has_Initial_Value
(E
)
1818 and then (No
(Unset_Reference
(E
))
1820 Earlier_In_Extended_Unit
1821 (Sloc
(N
), Sloc
(Unset_Reference
(E
))))
1822 and then not Has_Pragma_Unmodified_Check_Spec
(E
)
1823 and then not Warnings_Off_Check_Spec
(E
)
1824 and then not Has_Junk_Name
(E
)
1826 -- We may have an unset reference. The first test is whether
1827 -- this is an access to a discriminant of a record or a
1828 -- component with default initialization. Both of these
1829 -- cases can be ignored, since the actual object that is
1830 -- referenced is definitely initialized. Note that this
1831 -- covers the case of reading discriminants of an OUT
1832 -- parameter, which is OK even in Ada 83.
1834 -- Note that we are only interested in a direct reference to
1835 -- a record component here. If the reference is through an
1836 -- access type, then the access object is being referenced,
1837 -- not the record, and still deserves an unset reference.
1839 if Nkind
(Parent
(N
)) = N_Selected_Component
1840 and not Is_Access_Type
(Typ
)
1843 ES
: constant Entity_Id
:=
1844 Entity
(Selector_Name
(Parent
(N
)));
1846 if Ekind
(ES
) = E_Discriminant
1848 (Present
(Declaration_Node
(ES
))
1850 Present
(Expression
(Declaration_Node
(ES
))))
1857 -- Exclude fully initialized types
1859 if Is_OK_Fully_Initialized
then
1863 -- Here we have a potential unset reference. But before we
1864 -- get worried about it, we have to make sure that the
1865 -- entity declaration is in the same procedure as the
1866 -- reference, since if they are in separate procedures, then
1867 -- we have no idea about sequential execution.
1869 -- The tests in the loop below catch all such cases, but do
1870 -- allow the reference to appear in a loop, block, or
1871 -- package spec that is nested within the declaring scope.
1872 -- As always, it is possible to construct cases where the
1873 -- warning is wrong, that is why it is a warning.
1875 Potential_Unset_Reference
: declare
1877 SE
: constant Entity_Id
:= Scope
(E
);
1879 function Within_Postcondition
return Boolean;
1880 -- Returns True if N is within a Postcondition, a
1881 -- Refined_Post, an Ensures component in a Test_Case,
1882 -- or a Contract_Cases.
1884 --------------------------
1885 -- Within_Postcondition --
1886 --------------------------
1888 function Within_Postcondition
return Boolean is
1893 while Present
(Nod
) loop
1894 if Nkind
(Nod
) = N_Pragma
1895 and then Nam_In
(Pragma_Name_Unmapped
(Nod
),
1898 Name_Contract_Cases
)
1902 elsif Present
(Parent
(Nod
)) then
1905 if Nkind
(P
) = N_Pragma
1906 and then Pragma_Name
(P
) =
1908 and then Nod
= Test_Case_Arg
(P
, Name_Ensures
)
1914 Nod
:= Parent
(Nod
);
1918 end Within_Postcondition
;
1920 -- Start of processing for Potential_Unset_Reference
1923 SR
:= Current_Scope
;
1925 if SR
= Standard_Standard
1926 or else Is_Subprogram
(SR
)
1927 or else Is_Concurrent_Body
(SR
)
1928 or else Is_Concurrent_Type
(SR
)
1936 -- Case of reference has an access type. This is a
1937 -- special case since access types are always set to null
1938 -- so cannot be truly uninitialized, but we still want to
1939 -- warn about cases of obvious null dereference.
1941 if Is_Access_Type
(Typ
) then
1942 Access_Type_Case
: declare
1946 (N
: Node_Id
) return Traverse_Result
;
1947 -- Process function for instantiation of Traverse
1948 -- below. Checks if N contains reference to E other
1949 -- than a dereference.
1951 function Ref_In
(Nod
: Node_Id
) return Boolean;
1952 -- Determines whether Nod contains a reference to
1953 -- the entity E that is not a dereference.
1960 (N
: Node_Id
) return Traverse_Result
1963 if Is_Entity_Name
(N
)
1964 and then Entity
(N
) = E
1965 and then not Is_Dereferenced
(N
)
1977 function Ref_In
(Nod
: Node_Id
) return Boolean is
1978 function Traverse
is new Traverse_Func
(Process
);
1980 return Traverse
(Nod
) = Abandon
;
1983 -- Start of processing for Access_Type_Case
1986 -- Don't bother if we are inside an instance, since
1987 -- the compilation of the generic template is where
1988 -- the warning should be issued.
1994 -- Don't bother if this is not the main unit. If we
1995 -- try to give this warning for with'ed units, we
1996 -- get some false positives, since we do not record
1997 -- references in other units.
1999 if not In_Extended_Main_Source_Unit
(E
)
2001 not In_Extended_Main_Source_Unit
(N
)
2006 -- We are only interested in dereferences
2008 if not Is_Dereferenced
(N
) then
2012 -- One more check, don't bother with references
2013 -- that are inside conditional statements or WHILE
2014 -- loops if the condition references the entity in
2015 -- question. This avoids most false positives.
2022 if Nkind_In
(P
, N_If_Statement
, N_Elsif_Part
)
2023 and then Ref_In
(Condition
(P
))
2027 elsif Nkind
(P
) = N_Loop_Statement
2028 and then Present
(Iteration_Scheme
(P
))
2030 Ref_In
(Condition
(Iteration_Scheme
(P
)))
2035 end Access_Type_Case
;
2038 -- One more check, don't bother if we are within a
2039 -- postcondition, since the expression occurs in a
2040 -- place unrelated to the actual test.
2042 if not Within_Postcondition
then
2044 -- Here we definitely have a case for giving a warning
2045 -- for a reference to an unset value. But we don't
2046 -- give the warning now. Instead set Unset_Reference
2047 -- in the identifier involved. The reason for this is
2048 -- that if we find the variable is never ever assigned
2049 -- a value then that warning is more important and
2050 -- there is no point in giving the reference warning.
2052 -- If this is an identifier, set the field directly
2054 if Nkind
(N
) = N_Identifier
then
2055 Set_Unset_Reference
(E
, N
);
2057 -- Otherwise it is an expanded name, so set the field
2058 -- of the actual identifier for the reference.
2061 Set_Unset_Reference
(E
, Selector_Name
(N
));
2064 end Potential_Unset_Reference
;
2068 -- Indexed component or slice
2070 when N_Indexed_Component
2073 -- If prefix does not involve dereferencing an access type, then
2074 -- we know we are OK if the component type is fully initialized,
2075 -- since the component will have been set as part of the default
2078 if not Prefix_Has_Dereference
(Prefix
(N
))
2079 and then Is_OK_Fully_Initialized
2083 -- Look at prefix in access type case, or if the component is not
2084 -- fully initialized.
2087 Check_Unset_Reference
(Prefix
(N
));
2092 when N_Selected_Component
=>
2094 Pref
: constant Node_Id
:= Prefix
(N
);
2095 Ent
: constant Entity_Id
:= Entity
(Selector_Name
(N
));
2098 -- If prefix involves dereferencing an access type, always
2099 -- check the prefix, since the issue then is whether this
2100 -- access value is null.
2102 if Prefix_Has_Dereference
(Pref
) then
2105 -- Always go to prefix if no selector entity is set. Can this
2106 -- happen in the normal case? Not clear, but it definitely can
2107 -- happen in error cases.
2112 -- For a record component, check some cases where we have
2113 -- reasonable cause to consider that the component is known to
2114 -- be or probably is initialized. In this case, we don't care
2115 -- if the prefix itself was explicitly initialized.
2117 -- Discriminants are always considered initialized
2119 elsif Ekind
(Ent
) = E_Discriminant
then
2122 -- An explicitly initialized component is certainly initialized
2124 elsif Nkind
(Parent
(Ent
)) = N_Component_Declaration
2125 and then Present
(Expression
(Parent
(Ent
)))
2129 -- A fully initialized component is initialized
2131 elsif Is_OK_Fully_Initialized
then
2135 -- If none of those cases apply, check the record type prefix
2137 Check_Unset_Reference
(Pref
);
2140 -- For type conversions, qualifications, or expressions with actions,
2141 -- examine the expression.
2143 when N_Expression_With_Actions
2144 | N_Qualified_Expression
2147 Check_Unset_Reference
(Expression
(N
));
2149 -- For explicit dereference, always check prefix, which will generate
2150 -- an unset reference (since this is a case of dereferencing null).
2152 when N_Explicit_Dereference
=>
2153 Check_Unset_Reference
(Prefix
(N
));
2155 -- All other cases are not cases of an unset reference
2160 end Check_Unset_Reference
;
2162 ------------------------
2163 -- Check_Unused_Withs --
2164 ------------------------
2166 procedure Check_Unused_Withs
(Spec_Unit
: Unit_Number_Type
:= No_Unit
) is
2172 Munite
: constant Entity_Id
:= Cunit_Entity
(Main_Unit
);
2173 -- This is needed for checking the special renaming case
2175 procedure Check_One_Unit
(Unit
: Unit_Number_Type
);
2176 -- Subsidiary procedure, performs checks for specified unit
2178 --------------------
2179 -- Check_One_Unit --
2180 --------------------
2182 procedure Check_One_Unit
(Unit
: Unit_Number_Type
) is
2183 Is_Visible_Renaming
: Boolean := False;
2186 procedure Check_Inner_Package
(Pack
: Entity_Id
);
2187 -- Pack is a package local to a unit in a with_clause. Both the unit
2188 -- and Pack are referenced. If none of the entities in Pack are
2189 -- referenced, then the only occurrence of Pack is in a USE clause
2190 -- or a pragma, and a warning is worthwhile as well.
2192 function Check_System_Aux
return Boolean;
2193 -- Before giving a warning on a with_clause for System, check whether
2194 -- a system extension is present.
2196 function Find_Package_Renaming
2198 L
: Entity_Id
) return Entity_Id
;
2199 -- The only reference to a context unit may be in a renaming
2200 -- declaration. If this renaming declares a visible entity, do not
2201 -- warn that the context clause could be moved to the body, because
2202 -- the renaming may be intended to re-export the unit.
2204 function Has_Visible_Entities
(P
: Entity_Id
) return Boolean;
2205 -- This function determines if a package has any visible entities.
2206 -- True is returned if there is at least one declared visible entity,
2207 -- otherwise False is returned (e.g. case of only pragmas present).
2209 -------------------------
2210 -- Check_Inner_Package --
2211 -------------------------
2213 procedure Check_Inner_Package
(Pack
: Entity_Id
) is
2215 Un
: constant Node_Id
:= Sinfo
.Unit
(Cnode
);
2217 function Check_Use_Clause
(N
: Node_Id
) return Traverse_Result
;
2218 -- If N is a use_clause for Pack, emit warning
2220 procedure Check_Use_Clauses
is new
2221 Traverse_Proc
(Check_Use_Clause
);
2223 ----------------------
2224 -- Check_Use_Clause --
2225 ----------------------
2227 function Check_Use_Clause
(N
: Node_Id
) return Traverse_Result
is
2231 if Nkind
(N
) = N_Use_Package_Clause
then
2232 Nam
:= First
(Names
(N
));
2233 while Present
(Nam
) loop
2234 if Entity
(Nam
) = Pack
then
2236 -- Suppress message if any serious errors detected
2237 -- that turn off expansion, and thus result in false
2238 -- positives for this warning.
2240 if Serious_Errors_Detected
= 0 then
2241 Error_Msg_Qual_Level
:= 1;
2242 Error_Msg_NE
-- CODEFIX
2243 ("?u?no entities of package& are referenced!",
2245 Error_Msg_Qual_Level
:= 0;
2254 end Check_Use_Clause
;
2256 -- Start of processing for Check_Inner_Package
2259 E
:= First_Entity
(Pack
);
2260 while Present
(E
) loop
2261 if Referenced_Check_Spec
(E
) then
2268 -- No entities of the package are referenced. Check whether the
2269 -- reference to the package itself is a use clause, and if so
2270 -- place a warning on it.
2272 Check_Use_Clauses
(Un
);
2273 end Check_Inner_Package
;
2275 ----------------------
2276 -- Check_System_Aux --
2277 ----------------------
2279 function Check_System_Aux
return Boolean is
2283 if Chars
(Lunit
) = Name_System
2284 and then Scope
(Lunit
) = Standard_Standard
2285 and then Present_System_Aux
2287 Ent
:= First_Entity
(System_Aux_Id
);
2288 while Present
(Ent
) loop
2289 if Referenced_Check_Spec
(Ent
) then
2298 end Check_System_Aux
;
2300 ---------------------------
2301 -- Find_Package_Renaming --
2302 ---------------------------
2304 function Find_Package_Renaming
2306 L
: Entity_Id
) return Entity_Id
2312 Is_Visible_Renaming
:= False;
2314 E1
:= First_Entity
(P
);
2315 while Present
(E1
) loop
2316 if Ekind
(E1
) = E_Package
and then Renamed_Object
(E1
) = L
then
2317 Is_Visible_Renaming
:= not Is_Hidden
(E1
);
2320 elsif Ekind
(E1
) = E_Package
2321 and then No
(Renamed_Object
(E1
))
2322 and then not Is_Generic_Instance
(E1
)
2324 R
:= Find_Package_Renaming
(E1
, L
);
2327 Is_Visible_Renaming
:= not Is_Hidden
(R
);
2336 end Find_Package_Renaming
;
2338 --------------------------
2339 -- Has_Visible_Entities --
2340 --------------------------
2342 function Has_Visible_Entities
(P
: Entity_Id
) return Boolean is
2346 -- If unit in context is not a package, it is a subprogram that
2347 -- is not called or a generic unit that is not instantiated
2348 -- in the current unit, and warning is appropriate.
2350 if Ekind
(P
) /= E_Package
then
2354 -- If unit comes from a limited_with clause, look for declaration
2355 -- of shadow entities.
2357 if Present
(Limited_View
(P
)) then
2358 E
:= First_Entity
(Limited_View
(P
));
2360 E
:= First_Entity
(P
);
2363 while Present
(E
) and then E
/= First_Private_Entity
(P
) loop
2364 if Comes_From_Source
(E
) or else Present
(Limited_View
(P
)) then
2372 end Has_Visible_Entities
;
2374 -- Start of processing for Check_One_Unit
2377 Cnode
:= Cunit
(Unit
);
2379 -- Only do check in units that are part of the extended main unit.
2380 -- This is actually a necessary restriction, because in the case of
2381 -- subprogram acting as its own specification, there can be with's in
2382 -- subunits that we will not see.
2384 if not In_Extended_Main_Source_Unit
(Cnode
) then
2388 -- Loop through context items in this unit
2390 Item
:= First
(Context_Items
(Cnode
));
2391 while Present
(Item
) loop
2392 if Nkind
(Item
) = N_With_Clause
2393 and then not Implicit_With
(Item
)
2394 and then In_Extended_Main_Source_Unit
(Item
)
2396 -- Guard for no entity present. Not clear under what conditions
2397 -- this happens, but it does occur, and since this is only a
2398 -- warning, we just suppress the warning in this case.
2400 and then Nkind
(Name
(Item
)) in N_Has_Entity
2401 and then Present
(Entity
(Name
(Item
)))
2403 Lunit
:= Entity
(Name
(Item
));
2405 -- Check if this unit is referenced (skip the check if this
2406 -- is explicitly marked by a pragma Unreferenced).
2408 if not Referenced
(Lunit
) and then not Has_Unreferenced
(Lunit
)
2410 -- Suppress warnings in internal units if not in -gnatg mode
2411 -- (these would be junk warnings for an application program,
2412 -- since they refer to problems in internal units).
2414 if GNAT_Mode
or else not Is_Internal_Unit
(Unit
) then
2415 -- Here we definitely have a non-referenced unit. If it
2416 -- is the special call for a spec unit, then just set the
2417 -- flag to be read later.
2419 if Unit
= Spec_Unit
then
2420 Set_Unreferenced_In_Spec
(Item
);
2422 -- Otherwise simple unreferenced message, but skip this
2423 -- if no visible entities, because that is most likely a
2424 -- case where warning would be false positive (e.g. a
2425 -- package with only a linker options pragma and nothing
2426 -- else or a pragma elaborate with a body library task).
2428 elsif Has_Visible_Entities
(Entity
(Name
(Item
))) then
2429 Error_Msg_N
-- CODEFIX
2430 ("?u?unit& is not referenced!", Name
(Item
));
2434 -- If main unit is a renaming of this unit, then we consider
2435 -- the with to be OK (obviously it is needed in this case).
2436 -- This may be transitive: the unit in the with_clause may
2437 -- itself be a renaming, in which case both it and the main
2438 -- unit rename the same ultimate package.
2440 elsif Present
(Renamed_Entity
(Munite
))
2442 (Renamed_Entity
(Munite
) = Lunit
2443 or else Renamed_Entity
(Munite
) = Renamed_Entity
(Lunit
))
2447 -- If this unit is referenced, and it is a package, we do
2448 -- another test, to see if any of the entities in the package
2449 -- are referenced. If none of the entities are referenced, we
2450 -- still post a warning. This occurs if the only use of the
2451 -- package is in a use clause, or in a package renaming
2452 -- declaration. This check is skipped for packages that are
2453 -- renamed in a spec, since the entities in such a package are
2454 -- visible to clients via the renaming.
2456 elsif Ekind
(Lunit
) = E_Package
2457 and then not Renamed_In_Spec
(Lunit
)
2459 -- If Is_Instantiated is set, it means that the package is
2460 -- implicitly instantiated (this is the case of parent
2461 -- instance or an actual for a generic package formal), and
2462 -- this counts as a reference.
2464 if Is_Instantiated
(Lunit
) then
2467 -- If no entities in package, and there is a pragma
2468 -- Elaborate_Body present, then assume that this with is
2469 -- done for purposes of this elaboration.
2471 elsif No
(First_Entity
(Lunit
))
2472 and then Has_Pragma_Elaborate_Body
(Lunit
)
2476 -- Otherwise see if any entities have been referenced
2479 if Limited_Present
(Item
) then
2480 Ent
:= First_Entity
(Limited_View
(Lunit
));
2482 Ent
:= First_Entity
(Lunit
);
2486 -- No more entities, and we did not find one that was
2487 -- referenced. Means we have a definite case of a with
2488 -- none of whose entities was referenced.
2492 -- If in spec, just set the flag
2494 if Unit
= Spec_Unit
then
2495 Set_No_Entities_Ref_In_Spec
(Item
);
2497 elsif Check_System_Aux
then
2500 -- Else the warning may be needed
2504 Eitem
: constant Entity_Id
:=
2505 Entity
(Name
(Item
));
2508 -- Warn if we unreferenced flag set and we
2509 -- have not had serious errors. The reason we
2510 -- inhibit the message if there are errors is
2511 -- to prevent false positives from disabling
2514 if not Has_Unreferenced
(Eitem
)
2515 and then Serious_Errors_Detected
= 0
2517 -- Get possible package renaming
2520 Find_Package_Renaming
(Munite
, Lunit
);
2522 -- No warning if either the package or its
2523 -- renaming is used as a generic actual.
2525 if Used_As_Generic_Actual
(Eitem
)
2529 Used_As_Generic_Actual
(Pack
))
2534 -- Here we give the warning
2536 Error_Msg_N
-- CODEFIX
2537 ("?u?no entities of & are referenced!",
2540 -- Flag renaming of package as well. If
2541 -- the original package has warnings off,
2542 -- we suppress the warning on the renaming
2546 and then not Has_Warnings_Off
(Lunit
)
2547 and then not Has_Unreferenced
(Pack
)
2549 Error_Msg_NE
-- CODEFIX
2550 ("?u?no entities of& are referenced!",
2551 Unit_Declaration_Node
(Pack
), Pack
);
2559 -- Case of entity being referenced. The reference may
2560 -- come from a limited_with_clause, in which case the
2561 -- limited view of the entity carries the flag.
2563 elsif Referenced_Check_Spec
(Ent
)
2564 or else Referenced_As_LHS_Check_Spec
(Ent
)
2565 or else Referenced_As_Out_Parameter_Check_Spec
(Ent
)
2567 (From_Limited_With
(Ent
)
2568 and then Is_Incomplete_Type
(Ent
)
2569 and then Present
(Non_Limited_View
(Ent
))
2570 and then Referenced
(Non_Limited_View
(Ent
)))
2572 -- This means that the with is indeed fine, in that
2573 -- it is definitely needed somewhere, and we can
2574 -- quit worrying about this one...
2576 -- Except for one little detail: if either of the
2577 -- flags was set during spec processing, this is
2578 -- where we complain that the with could be moved
2579 -- from the spec. If the spec contains a visible
2580 -- renaming of the package, inhibit warning to move
2581 -- with_clause to body.
2583 if Ekind
(Munite
) = E_Package_Body
then
2585 Find_Package_Renaming
2586 (Spec_Entity
(Munite
), Lunit
);
2591 -- If a renaming is present in the spec do not warn
2592 -- because the body or child unit may depend on it.
2595 and then Renamed_Entity
(Pack
) = Lunit
2599 elsif Unreferenced_In_Spec
(Item
) then
2600 Error_Msg_N
-- CODEFIX
2601 ("?u?unit& is not referenced in spec!",
2604 elsif No_Entities_Ref_In_Spec
(Item
) then
2605 Error_Msg_N
-- CODEFIX
2606 ("?u?no entities of & are referenced in spec!",
2610 if Ekind
(Ent
) = E_Package
then
2611 Check_Inner_Package
(Ent
);
2617 if not Is_Visible_Renaming
then
2618 Error_Msg_N
-- CODEFIX
2619 ("\?u?with clause might be moved to body!",
2625 -- Move to next entity to continue search
2633 -- For a generic package, the only interesting kind of
2634 -- reference is an instantiation, since entities cannot be
2635 -- referenced directly.
2637 elsif Is_Generic_Unit
(Lunit
) then
2639 -- Unit was never instantiated, set flag for case of spec
2640 -- call, or give warning for normal call.
2642 if not Is_Instantiated
(Lunit
) then
2643 if Unit
= Spec_Unit
then
2644 Set_Unreferenced_In_Spec
(Item
);
2646 Error_Msg_N
-- CODEFIX
2647 ("?u?unit& is never instantiated!", Name
(Item
));
2650 -- If unit was indeed instantiated, make sure that flag is
2651 -- not set showing it was uninstantiated in the spec, and if
2652 -- so, give warning.
2654 elsif Unreferenced_In_Spec
(Item
) then
2656 ("?u?unit& is not instantiated in spec!", Name
(Item
));
2657 Error_Msg_N
-- CODEFIX
2658 ("\?u?with clause can be moved to body!", Name
(Item
));
2667 -- Start of processing for Check_Unused_Withs
2670 -- Immediate return if no semantics or warning flag not set
2672 if not Opt
.Check_Withs
or else Operating_Mode
= Check_Syntax
then
2676 Process_Deferred_References
;
2678 -- Flag any unused with clauses. For a subunit, check only the units
2679 -- in its context, not those of the parent, which may be needed by other
2680 -- subunits. We will get the full warnings when we compile the parent,
2681 -- but the following is helpful when compiling a subunit by itself.
2683 if Nkind
(Unit
(Cunit
(Main_Unit
))) = N_Subunit
then
2684 if Current_Sem_Unit
= Main_Unit
then
2685 Check_One_Unit
(Main_Unit
);
2691 -- Process specified units
2693 if Spec_Unit
= No_Unit
then
2695 -- For main call, check all units
2697 for Unit
in Main_Unit
.. Last_Unit
loop
2698 Check_One_Unit
(Unit
);
2702 -- For call for spec, check only the spec
2704 Check_One_Unit
(Spec_Unit
);
2706 end Check_Unused_Withs
;
2708 ---------------------------------
2709 -- Generic_Package_Spec_Entity --
2710 ---------------------------------
2712 function Generic_Package_Spec_Entity
(E
: Entity_Id
) return Boolean is
2716 if Is_Package_Body_Entity
(E
) then
2722 if S
= Standard_Standard
then
2725 elsif Ekind
(S
) = E_Generic_Package
then
2728 elsif Ekind
(S
) = E_Package
then
2736 end Generic_Package_Spec_Entity
;
2738 ----------------------
2739 -- Goto_Spec_Entity --
2740 ----------------------
2742 function Goto_Spec_Entity
(E
: Entity_Id
) return Entity_Id
is
2744 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2745 return Spec_Entity
(E
);
2749 end Goto_Spec_Entity
;
2755 function Has_Junk_Name
(E
: Entity_Id
) return Boolean is
2756 function Match
(S
: String) return Boolean;
2757 -- Return true if substring S is found in Name_Buffer (1 .. Name_Len)
2763 function Match
(S
: String) return Boolean is
2764 Slen1
: constant Integer := S
'Length - 1;
2767 for J
in 1 .. Name_Len
- S
'Length + 1 loop
2768 if Name_Buffer
(J
.. J
+ Slen1
) = S
then
2776 -- Start of processing for Has_Junk_Name
2779 Get_Unqualified_Decoded_Name_String
(Chars
(E
));
2782 Match
("discard") or else
2783 Match
("dummy") or else
2784 Match
("ignore") or else
2785 Match
("junk") or else
2789 --------------------------------------
2790 -- Has_Pragma_Unmodified_Check_Spec --
2791 --------------------------------------
2793 function Has_Pragma_Unmodified_Check_Spec
2794 (E
: Entity_Id
) return Boolean
2797 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2799 -- Note: use of OR instead of OR ELSE here is deliberate, we want
2800 -- to mess with Unmodified flags on both body and spec entities.
2802 return Has_Unmodified
(E
)
2804 Has_Unmodified
(Spec_Entity
(E
));
2807 return Has_Unmodified
(E
);
2809 end Has_Pragma_Unmodified_Check_Spec
;
2811 ----------------------------------------
2812 -- Has_Pragma_Unreferenced_Check_Spec --
2813 ----------------------------------------
2815 function Has_Pragma_Unreferenced_Check_Spec
2816 (E
: Entity_Id
) return Boolean
2819 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2821 -- Note: use of OR here instead of OR ELSE is deliberate, we want
2822 -- to mess with flags on both entities.
2824 return Has_Unreferenced
(E
)
2826 Has_Unreferenced
(Spec_Entity
(E
));
2829 return Has_Unreferenced
(E
);
2831 end Has_Pragma_Unreferenced_Check_Spec
;
2837 procedure Initialize
is
2839 Warnings_Off_Pragmas
.Init
;
2840 Unreferenced_Entities
.Init
;
2841 In_Out_Warnings
.Init
;
2844 ---------------------------------------------
2845 -- Is_Attribute_And_Known_Value_Comparison --
2846 ---------------------------------------------
2848 function Is_Attribute_And_Known_Value_Comparison
2849 (Op
: Node_Id
) return Boolean
2851 Orig_Op
: constant Node_Id
:= Original_Node
(Op
);
2855 Nkind
(Orig_Op
) in N_Op_Compare
2856 and then Nkind
(Original_Node
(Left_Opnd
(Orig_Op
))) =
2857 N_Attribute_Reference
2858 and then Compile_Time_Known_Value
(Right_Opnd
(Orig_Op
));
2859 end Is_Attribute_And_Known_Value_Comparison
;
2861 ------------------------------------
2862 -- Never_Set_In_Source_Check_Spec --
2863 ------------------------------------
2865 function Never_Set_In_Source_Check_Spec
(E
: Entity_Id
) return Boolean is
2867 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
2868 return Never_Set_In_Source
(E
)
2870 Never_Set_In_Source
(Spec_Entity
(E
));
2872 return Never_Set_In_Source
(E
);
2874 end Never_Set_In_Source_Check_Spec
;
2876 -------------------------------------
2877 -- Operand_Has_Warnings_Suppressed --
2878 -------------------------------------
2880 function Operand_Has_Warnings_Suppressed
(N
: Node_Id
) return Boolean is
2882 function Check_For_Warnings
(N
: Node_Id
) return Traverse_Result
;
2883 -- Function used to check one node to see if it is or was originally
2884 -- a reference to an entity for which Warnings are off. If so, Abandon
2885 -- is returned, otherwise OK_Orig is returned to continue the traversal
2886 -- of the original expression.
2888 function Traverse
is new Traverse_Func
(Check_For_Warnings
);
2889 -- Function used to traverse tree looking for warnings
2891 ------------------------
2892 -- Check_For_Warnings --
2893 ------------------------
2895 function Check_For_Warnings
(N
: Node_Id
) return Traverse_Result
is
2896 R
: constant Node_Id
:= Original_Node
(N
);
2899 if Nkind
(R
) in N_Has_Entity
2900 and then Present
(Entity
(R
))
2901 and then Has_Warnings_Off
(Entity
(R
))
2907 end Check_For_Warnings
;
2909 -- Start of processing for Operand_Has_Warnings_Suppressed
2912 return Traverse
(N
) = Abandon
;
2914 -- If any exception occurs, then something has gone wrong, and this is
2915 -- only a minor aesthetic issue anyway, so just say we did not find what
2916 -- we are looking for, rather than blow up.
2921 end Operand_Has_Warnings_Suppressed
;
2923 -----------------------------------------
2924 -- Output_Non_Modified_In_Out_Warnings --
2925 -----------------------------------------
2927 procedure Output_Non_Modified_In_Out_Warnings
is
2929 function No_Warn_On_In_Out
(E
: Entity_Id
) return Boolean;
2930 -- Given a formal parameter entity E, determines if there is a reason to
2931 -- suppress IN OUT warnings (not modified, could be IN) for formals of
2932 -- the subprogram. We suppress these warnings if Warnings Off is set, or
2933 -- if we have seen the address of the subprogram being taken, or if the
2934 -- subprogram is used as a generic actual (in the latter cases the
2935 -- context may force use of IN OUT, even if the parameter is not
2936 -- modifies for this particular case.
2938 -----------------------
2939 -- No_Warn_On_In_Out --
2940 -----------------------
2942 function No_Warn_On_In_Out
(E
: Entity_Id
) return Boolean is
2943 S
: constant Entity_Id
:= Scope
(E
);
2944 SE
: constant Entity_Id
:= Spec_Entity
(E
);
2947 -- Do not warn if address is taken, since funny business may be going
2948 -- on in treating the parameter indirectly as IN OUT.
2950 if Address_Taken
(S
)
2951 or else (Present
(SE
) and then Address_Taken
(Scope
(SE
)))
2955 -- Do not warn if used as a generic actual, since the generic may be
2956 -- what is forcing the use of an "unnecessary" IN OUT.
2958 elsif Used_As_Generic_Actual
(S
)
2959 or else (Present
(SE
) and then Used_As_Generic_Actual
(Scope
(SE
)))
2963 -- Else test warnings off
2965 elsif Warnings_Off_Check_Spec
(S
) then
2968 -- All tests for suppressing warning failed
2973 end No_Warn_On_In_Out
;
2975 -- Start of processing for Output_Non_Modified_In_Out_Warnings
2978 -- Loop through entities for which a warning may be needed
2980 for J
in In_Out_Warnings
.First
.. In_Out_Warnings
.Last
loop
2982 E1
: constant Entity_Id
:= In_Out_Warnings
.Table
(J
);
2985 -- Suppress warning in specific cases (see details in comments for
2986 -- No_Warn_On_In_Out), or if there is a pragma Unmodified.
2988 if Has_Pragma_Unmodified_Check_Spec
(E1
)
2989 or else No_Warn_On_In_Out
(E1
)
2993 -- Here we generate the warning
2996 -- If -gnatwc is set then output message that we could be IN
2998 if not Is_Trivial_Subprogram
(Scope
(E1
)) then
2999 if Warn_On_Constant
then
3001 ("?u?formal parameter & is not modified!", E1
);
3003 ("\?u?mode could be IN instead of `IN OUT`!", E1
);
3005 -- We do not generate warnings for IN OUT parameters
3006 -- unless we have at least -gnatwu. This is deliberately
3007 -- inconsistent with the treatment of variables, but
3008 -- otherwise we get too many unexpected warnings in
3011 elsif Check_Unreferenced
then
3013 ("?u?formal parameter& is read but "
3014 & "never assigned!", E1
);
3018 -- Kill any other warnings on this entity, since this is the
3019 -- one that should dominate any other unreferenced warning.
3021 Set_Warnings_Off
(E1
);
3025 end Output_Non_Modified_In_Out_Warnings
;
3027 ----------------------------------------
3028 -- Output_Obsolescent_Entity_Warnings --
3029 ----------------------------------------
3031 procedure Output_Obsolescent_Entity_Warnings
(N
: Node_Id
; E
: Entity_Id
) is
3032 P
: constant Node_Id
:= Parent
(N
);
3038 -- Do not output message if we are the scope of standard. This means
3039 -- we have a reference from a context clause from when it is originally
3040 -- processed, and that's too early to tell whether it is an obsolescent
3041 -- unit doing the with'ing. In Sem_Ch10.Analyze_Compilation_Unit we make
3042 -- sure that we have a later call when the scope is available. This test
3043 -- also eliminates all messages for use clauses, which is fine (we do
3044 -- not want messages for use clauses, since they are always redundant
3045 -- with respect to the associated with clause).
3047 if S
= Standard_Standard
then
3051 -- Do not output message if we are in scope of an obsolescent package
3055 if Is_Obsolescent
(S
) then
3060 exit when S
= Standard_Standard
;
3063 -- Here we will output the message
3065 Error_Msg_Sloc
:= Sloc
(E
);
3067 -- Case of with clause
3069 if Nkind
(P
) = N_With_Clause
then
3070 if Ekind
(E
) = E_Package
then
3072 ("?j?with of obsolescent package& declared#", N
, E
);
3073 elsif Ekind
(E
) = E_Procedure
then
3075 ("?j?with of obsolescent procedure& declared#", N
, E
);
3078 ("??with of obsolescent function& declared#", N
, E
);
3081 -- If we do not have a with clause, then ignore any reference to an
3082 -- obsolescent package name. We only want to give the one warning of
3083 -- withing the package, not one each time it is used to qualify.
3085 elsif Ekind
(E
) = E_Package
then
3088 -- Procedure call statement
3090 elsif Nkind
(P
) = N_Procedure_Call_Statement
then
3092 ("??call to obsolescent procedure& declared#", N
, E
);
3096 elsif Nkind
(P
) = N_Function_Call
then
3098 ("??call to obsolescent function& declared#", N
, E
);
3100 -- Reference to obsolescent type
3102 elsif Is_Type
(E
) then
3104 ("??reference to obsolescent type& declared#", N
, E
);
3106 -- Reference to obsolescent component
3108 elsif Ekind_In
(E
, E_Component
, E_Discriminant
) then
3110 ("??reference to obsolescent component& declared#", N
, E
);
3112 -- Reference to obsolescent variable
3114 elsif Ekind
(E
) = E_Variable
then
3116 ("??reference to obsolescent variable& declared#", N
, E
);
3118 -- Reference to obsolescent constant
3120 elsif Ekind
(E
) = E_Constant
or else Ekind
(E
) in Named_Kind
then
3122 ("??reference to obsolescent constant& declared#", N
, E
);
3124 -- Reference to obsolescent enumeration literal
3126 elsif Ekind
(E
) = E_Enumeration_Literal
then
3128 ("??reference to obsolescent enumeration literal& declared#", N
, E
);
3130 -- Generic message for any other case we missed
3134 ("??reference to obsolescent entity& declared#", N
, E
);
3137 -- Output additional warning if present
3139 for J
in Obsolescent_Warnings
.First
.. Obsolescent_Warnings
.Last
loop
3140 if Obsolescent_Warnings
.Table
(J
).Ent
= E
then
3141 String_To_Name_Buffer
(Obsolescent_Warnings
.Table
(J
).Msg
);
3142 Error_Msg_Strlen
:= Name_Len
;
3143 Error_Msg_String
(1 .. Name_Len
) := Name_Buffer
(1 .. Name_Len
);
3144 Error_Msg_N
("\\??~", N
);
3148 end Output_Obsolescent_Entity_Warnings
;
3150 ----------------------------------
3151 -- Output_Unreferenced_Messages --
3152 ----------------------------------
3154 procedure Output_Unreferenced_Messages
is
3156 for J
in Unreferenced_Entities
.First
.. Unreferenced_Entities
.Last
loop
3157 Warn_On_Unreferenced_Entity
(Unreferenced_Entities
.Table
(J
));
3159 end Output_Unreferenced_Messages
;
3161 -----------------------------------------
3162 -- Output_Unused_Warnings_Off_Warnings --
3163 -----------------------------------------
3165 procedure Output_Unused_Warnings_Off_Warnings
is
3167 for J
in Warnings_Off_Pragmas
.First
.. Warnings_Off_Pragmas
.Last
loop
3169 Wentry
: Warnings_Off_Entry
renames Warnings_Off_Pragmas
.Table
(J
);
3170 N
: Node_Id
renames Wentry
.N
;
3171 E
: Node_Id
renames Wentry
.E
;
3174 -- Turn off Warnings_Off, or we won't get the warning
3176 Set_Warnings_Off
(E
, False);
3178 -- Nothing to do if pragma was used to suppress a general warning
3180 if Warnings_Off_Used
(E
) then
3183 -- If pragma was used both in unmodified and unreferenced contexts
3184 -- then that's as good as the general case, no warning.
3186 elsif Warnings_Off_Used_Unmodified
(E
)
3188 Warnings_Off_Used_Unreferenced
(E
)
3192 -- Used only in context where Unmodified would have worked
3194 elsif Warnings_Off_Used_Unmodified
(E
) then
3196 ("?W?could use Unmodified instead of "
3197 & "Warnings Off for &", Pragma_Identifier
(N
), E
);
3199 -- Used only in context where Unreferenced would have worked
3201 elsif Warnings_Off_Used_Unreferenced
(E
) then
3203 ("?W?could use Unreferenced instead of "
3204 & "Warnings Off for &", Pragma_Identifier
(N
), E
);
3210 ("?W?pragma Warnings Off for & unused, "
3211 & "could be omitted", N
, E
);
3215 end Output_Unused_Warnings_Off_Warnings
;
3217 ---------------------------
3218 -- Referenced_Check_Spec --
3219 ---------------------------
3221 function Referenced_Check_Spec
(E
: Entity_Id
) return Boolean is
3223 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3224 return Referenced
(E
) or else Referenced
(Spec_Entity
(E
));
3226 return Referenced
(E
);
3228 end Referenced_Check_Spec
;
3230 ----------------------------------
3231 -- Referenced_As_LHS_Check_Spec --
3232 ----------------------------------
3234 function Referenced_As_LHS_Check_Spec
(E
: Entity_Id
) return Boolean is
3236 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3237 return Referenced_As_LHS
(E
)
3238 or else Referenced_As_LHS
(Spec_Entity
(E
));
3240 return Referenced_As_LHS
(E
);
3242 end Referenced_As_LHS_Check_Spec
;
3244 --------------------------------------------
3245 -- Referenced_As_Out_Parameter_Check_Spec --
3246 --------------------------------------------
3248 function Referenced_As_Out_Parameter_Check_Spec
3249 (E
: Entity_Id
) return Boolean
3252 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
3253 return Referenced_As_Out_Parameter
(E
)
3254 or else Referenced_As_Out_Parameter
(Spec_Entity
(E
));
3256 return Referenced_As_Out_Parameter
(E
);
3258 end Referenced_As_Out_Parameter_Check_Spec
;
3260 --------------------------------------
3261 -- Warn_On_Constant_Valid_Condition --
3262 --------------------------------------
3264 procedure Warn_On_Constant_Valid_Condition
(Op
: Node_Id
) is
3265 Left
: constant Node_Id
:= Left_Opnd
(Op
);
3266 Right
: constant Node_Id
:= Right_Opnd
(Op
);
3268 True_Result
: Boolean;
3269 False_Result
: Boolean;
3272 -- Determine the potential outcome of the comparison assuming that the
3273 -- scalar operands are valid.
3275 if Constant_Condition_Warnings
3276 and then Comes_From_Source
(Original_Node
(Op
))
3277 and then Is_Scalar_Type
(Etype
(Left
))
3278 and then Is_Scalar_Type
(Etype
(Right
))
3280 -- Do not consider instances because the check was already performed
3283 and then not In_Instance
3285 -- Do not consider comparisons between two static expressions such as
3286 -- constants or literals because those values cannot be invalidated.
3288 and then not (Is_Static_Expression
(Left
)
3289 and then Is_Static_Expression
(Right
))
3291 -- Do not consider comparison between an attribute reference and a
3292 -- compile-time known value since this is most likely a conditional
3295 and then not Is_Attribute_And_Known_Value_Comparison
(Op
)
3297 -- Do not consider internal files to allow for various assertions and
3298 -- safeguards within our runtime.
3300 and then not In_Internal_Unit
(Op
)
3304 Assume_Valid
=> True,
3305 True_Result
=> True_Result
,
3306 False_Result
=> False_Result
);
3308 -- Warn on a possible evaluation to False / True in the presence of
3313 ("condition can only be False if invalid values present??", Op
);
3315 elsif False_Result
then
3317 ("condition can only be True if invalid values present??", Op
);
3320 end Warn_On_Constant_Valid_Condition
;
3322 -----------------------------
3323 -- Warn_On_Known_Condition --
3324 -----------------------------
3326 procedure Warn_On_Known_Condition
(C
: Node_Id
) is
3327 Test_Result
: Boolean;
3329 function Is_Known_Branch
return Boolean;
3330 -- If the type of the condition is Boolean, the constant value of the
3331 -- condition is a boolean literal. If the type is a derived boolean
3332 -- type, the constant is wrapped in a type conversion of the derived
3333 -- literal. If the value of the condition is not a literal, no warnings
3334 -- can be produced. This function returns True if the result can be
3335 -- determined, and Test_Result is set True/False accordingly. Otherwise
3336 -- False is returned, and Test_Result is unchanged.
3338 procedure Track
(N
: Node_Id
; Loc
: Node_Id
);
3339 -- Adds continuation warning(s) pointing to reason (assignment or test)
3340 -- for the operand of the conditional having a known value (or at least
3341 -- enough is known about the value to issue the warning). N is the node
3342 -- which is judged to have a known value. Loc is the warning location.
3344 ---------------------
3345 -- Is_Known_Branch --
3346 ---------------------
3348 function Is_Known_Branch
return Boolean is
3350 if Etype
(C
) = Standard_Boolean
3351 and then Is_Entity_Name
(C
)
3353 (Entity
(C
) = Standard_False
or else Entity
(C
) = Standard_True
)
3355 Test_Result
:= Entity
(C
) = Standard_True
;
3358 elsif Is_Boolean_Type
(Etype
(C
))
3359 and then Nkind
(C
) = N_Unchecked_Type_Conversion
3360 and then Is_Entity_Name
(Expression
(C
))
3361 and then Ekind
(Entity
(Expression
(C
))) = E_Enumeration_Literal
3364 Chars
(Entity
(Expression
(C
))) = Chars
(Standard_True
);
3370 end Is_Known_Branch
;
3376 procedure Track
(N
: Node_Id
; Loc
: Node_Id
) is
3377 Nod
: constant Node_Id
:= Original_Node
(N
);
3380 if Nkind
(Nod
) in N_Op_Compare
then
3381 Track
(Left_Opnd
(Nod
), Loc
);
3382 Track
(Right_Opnd
(Nod
), Loc
);
3384 elsif Is_Entity_Name
(Nod
) and then Is_Object
(Entity
(Nod
)) then
3386 CV
: constant Node_Id
:= Current_Value
(Entity
(Nod
));
3389 if Present
(CV
) then
3390 Error_Msg_Sloc
:= Sloc
(CV
);
3392 if Nkind
(CV
) not in N_Subexpr
then
3393 Error_Msg_N
("\\??(see test #)", Loc
);
3395 elsif Nkind
(Parent
(CV
)) =
3396 N_Case_Statement_Alternative
3398 Error_Msg_N
("\\??(see case alternative #)", Loc
);
3401 Error_Msg_N
("\\??(see assignment #)", Loc
);
3410 Orig
: constant Node_Id
:= Original_Node
(C
);
3413 -- Start of processing for Warn_On_Known_Condition
3416 -- Adjust SCO condition if from source
3419 and then Comes_From_Source
(Orig
)
3420 and then Is_Known_Branch
3426 Atrue
:= Test_Result
;
3428 if Present
(Parent
(C
)) and then Nkind
(Parent
(C
)) = N_Op_Not
then
3432 Set_SCO_Condition
(Orig
, Atrue
);
3436 -- Argument replacement in an inlined body can make conditions static.
3437 -- Do not emit warnings in this case.
3439 if In_Inlined_Body
then
3443 if Constant_Condition_Warnings
3444 and then Is_Known_Branch
3445 and then Comes_From_Source
(Orig
)
3446 and then not In_Instance
3448 -- Don't warn if comparison of result of attribute against a constant
3449 -- value, since this is likely legitimate conditional compilation.
3451 if Is_Attribute_And_Known_Value_Comparison
(C
) then
3455 -- See if this is in a statement or a declaration
3459 -- If tree is not attached, do not issue warning (this is very
3460 -- peculiar, and probably arises from some other error condition).
3465 -- If we are in a declaration, then no warning, since in practice
3466 -- conditionals in declarations are used for intended tests which
3467 -- may be known at compile time, e.g. things like
3469 -- x : constant Integer := 2 + (Word'Size = 32);
3471 -- And a warning is annoying in such cases
3473 elsif Nkind
(P
) in N_Declaration
3475 Nkind
(P
) in N_Later_Decl_Item
3479 -- Don't warn in assert or check pragma, since presumably tests in
3480 -- such a context are very definitely intended, and might well be
3481 -- known at compile time. Note that we have to test the original
3482 -- node, since assert pragmas get rewritten at analysis time.
3484 elsif Nkind
(Original_Node
(P
)) = N_Pragma
3485 and then Nam_In
(Pragma_Name_Unmapped
(Original_Node
(P
)),
3486 Name_Assert
, Name_Check
)
3491 exit when Is_Statement
(P
);
3495 -- Here we issue the warning unless some sub-operand has warnings
3496 -- set off, in which case we suppress the warning for the node. If
3497 -- the original expression is an inequality, it has been expanded
3498 -- into a negation, and the value of the original expression is the
3499 -- negation of the equality. If the expression is an entity that
3500 -- appears within a negation, it is clearer to flag the negation
3501 -- itself, and report on its constant value.
3503 if not Operand_Has_Warnings_Suppressed
(C
) then
3505 True_Branch
: Boolean := Test_Result
;
3506 Cond
: Node_Id
:= C
;
3509 if Present
(Parent
(C
))
3510 and then Nkind
(Parent
(C
)) = N_Op_Not
3512 True_Branch
:= not True_Branch
;
3516 -- Condition always True
3519 if Is_Entity_Name
(Original_Node
(C
))
3520 and then Nkind
(Cond
) /= N_Op_Not
3523 ("object & is always True at this point?c?",
3524 Cond
, Original_Node
(C
));
3525 Track
(Original_Node
(C
), Cond
);
3528 Error_Msg_N
("condition is always True?c?", Cond
);
3532 -- Condition always False
3535 if Is_Entity_Name
(Original_Node
(C
))
3536 and then Nkind
(Cond
) /= N_Op_Not
3539 ("object & is always False at this point?c?",
3540 Cond
, Original_Node
(C
));
3541 Track
(Original_Node
(C
), Cond
);
3544 Error_Msg_N
("condition is always False?c?", Cond
);
3551 end Warn_On_Known_Condition
;
3553 ---------------------------------------
3554 -- Warn_On_Modified_As_Out_Parameter --
3555 ---------------------------------------
3557 function Warn_On_Modified_As_Out_Parameter
(E
: Entity_Id
) return Boolean is
3560 (Warn_On_Modified_Unread
and then Is_Only_Out_Parameter
(E
))
3561 or else Warn_On_All_Unread_Out_Parameters
;
3562 end Warn_On_Modified_As_Out_Parameter
;
3564 ---------------------------------
3565 -- Warn_On_Overlapping_Actuals --
3566 ---------------------------------
3568 procedure Warn_On_Overlapping_Actuals
(Subp
: Entity_Id
; N
: Node_Id
) is
3569 function Is_Covered_Formal
(Formal
: Node_Id
) return Boolean;
3570 -- Return True if Formal is covered by the rule
3572 function Refer_Same_Object
3574 Act2
: Node_Id
) return Boolean;
3575 -- Two names are known to refer to the same object if the two names
3576 -- are known to denote the same object; or one of the names is a
3577 -- selected_component, indexed_component, or slice and its prefix is
3578 -- known to refer to the same object as the other name; or one of the
3579 -- two names statically denotes a renaming declaration whose renamed
3580 -- object_name is known to refer to the same object as the other name
3581 -- (RM 6.4.1(6.11/3))
3583 -----------------------
3584 -- Is_Covered_Formal --
3585 -----------------------
3587 function Is_Covered_Formal
(Formal
: Node_Id
) return Boolean is
3590 Ekind_In
(Formal
, E_Out_Parameter
, E_In_Out_Parameter
)
3591 and then (Is_Elementary_Type
(Etype
(Formal
))
3592 or else Is_Record_Type
(Etype
(Formal
))
3593 or else Is_Array_Type
(Etype
(Formal
)));
3594 end Is_Covered_Formal
;
3596 -----------------------
3597 -- Refer_Same_Object --
3598 -----------------------
3600 function Refer_Same_Object
3602 Act2
: Node_Id
) return Boolean
3606 Denotes_Same_Object
(Act1
, Act2
)
3607 or else Denotes_Same_Prefix
(Act1
, Act2
);
3608 end Refer_Same_Object
;
3616 Warn_Only
: Boolean;
3617 -- GNAT warns on overlapping in-out parameters even when there are no
3618 -- two in-out parameters of an elementary type, as stated in
3621 -- Start of processing for Warn_On_Overlapping_Actuals
3625 if Ada_Version
< Ada_2012
and then not Warn_On_Overlap
then
3629 -- The call is illegal only if there are at least two in-out parameters
3630 -- of the same elementary type.
3633 Form1
:= First_Formal
(Subp
);
3634 while Present
(Form1
) loop
3635 Form2
:= Next_Formal
(Form1
);
3636 while Present
(Form2
) loop
3637 if Is_Elementary_Type
(Etype
(Form1
))
3638 and then Is_Elementary_Type
(Etype
(Form2
))
3639 and then Ekind
(Form1
) /= E_In_Parameter
3640 and then Ekind
(Form2
) /= E_In_Parameter
3646 Next_Formal
(Form2
);
3649 Next_Formal
(Form1
);
3652 -- Exclude calls rewritten as enumeration literals
3654 if Nkind
(N
) not in N_Subprogram_Call
3655 and then Nkind
(N
) /= N_Entry_Call_Statement
3660 -- If a call C has two or more parameters of mode in out or out that are
3661 -- of an elementary type, then the call is legal only if for each name
3662 -- N that is passed as a parameter of mode in out or out to the call C,
3663 -- there is no other name among the other parameters of mode in out or
3664 -- out to C that is known to denote the same object (RM 6.4.1(6.15/3))
3666 -- If appropriate warning switch is set, we also report warnings on
3667 -- overlapping parameters that are record types or array types.
3669 Form1
:= First_Formal
(Subp
);
3670 Act1
:= First_Actual
(N
);
3671 while Present
(Form1
) and then Present
(Act1
) loop
3672 if Is_Covered_Formal
(Form1
) then
3673 Form2
:= First_Formal
(Subp
);
3674 Act2
:= First_Actual
(N
);
3675 while Present
(Form2
) and then Present
(Act2
) loop
3677 and then Is_Covered_Formal
(Form2
)
3678 and then Refer_Same_Object
(Act1
, Act2
)
3680 -- Guard against previous errors
3683 or else No
(Etype
(Act1
))
3684 or else No
(Etype
(Act2
))
3688 -- If the actual is a function call in prefix notation,
3689 -- there is no real overlap.
3691 elsif Nkind
(Act2
) = N_Function_Call
then
3694 -- If type is not by-copy, assume that aliasing is intended
3697 Present
(Underlying_Type
(Etype
(Form1
)))
3699 (Is_By_Reference_Type
(Underlying_Type
(Etype
(Form1
)))
3701 Convention
(Underlying_Type
(Etype
(Form1
))) =
3702 Convention_Ada_Pass_By_Reference
)
3706 -- Under Ada 2012 we only report warnings on overlapping
3707 -- arrays and record types if switch is set.
3709 elsif Ada_Version
>= Ada_2012
3710 and then not Is_Elementary_Type
(Etype
(Form1
))
3711 and then not Warn_On_Overlap
3715 -- Here we may need to issue overlap message
3720 -- Overlap checking is an error only in Ada 2012. For
3721 -- earlier versions of Ada, this is a warning.
3723 Ada_Version
< Ada_2012
3725 -- Overlap is only illegal in Ada 2012 in the case of
3726 -- elementary types (passed by copy). For other types,
3727 -- we always have a warning in all Ada versions.
3729 or else not Is_Elementary_Type
(Etype
(Form1
))
3731 -- debug flag -gnatd.E changes the error to a warning
3732 -- even in Ada 2012 mode.
3734 or else Error_To_Warning
3742 -- Find matching actual
3744 Act
:= First_Actual
(N
);
3745 Form
:= First_Formal
(Subp
);
3746 while Act
/= Act2
loop
3751 if Is_Elementary_Type
(Etype
(Act1
))
3752 and then Ekind
(Form2
) = E_In_Parameter
3754 null; -- No real aliasing
3756 elsif Is_Elementary_Type
(Etype
(Act2
))
3757 and then Ekind
(Form2
) = E_In_Parameter
3761 -- If the call was written in prefix notation, and
3762 -- thus its prefix before rewriting was a selected
3763 -- component, count only visible actuals in the call.
3765 elsif Is_Entity_Name
(First_Actual
(N
))
3766 and then Nkind
(Original_Node
(N
)) = Nkind
(N
)
3767 and then Nkind
(Name
(Original_Node
(N
))) =
3768 N_Selected_Component
3770 Is_Entity_Name
(Prefix
(Name
(Original_Node
(N
))))
3772 Entity
(Prefix
(Name
(Original_Node
(N
)))) =
3773 Entity
(First_Actual
(N
))
3775 if Act1
= First_Actual
(N
) then
3777 ("<<`IN OUT` prefix overlaps with "
3778 & "actual for&", Act1
, Form
);
3781 -- For greater clarity, give name of formal
3783 Error_Msg_Node_2
:= Form
;
3785 ("<<writable actual for & overlaps with "
3786 & "actual for&", Act1
, Form
);
3790 -- For greater clarity, give name of formal
3792 Error_Msg_Node_2
:= Form
;
3794 -- This is one of the messages
3797 ("<<writable actual for & overlaps with "
3798 & "actual for&", Act1
, Form1
);
3806 Next_Formal
(Form2
);
3811 Next_Formal
(Form1
);
3814 end Warn_On_Overlapping_Actuals
;
3816 ------------------------------
3817 -- Warn_On_Suspicious_Index --
3818 ------------------------------
3820 procedure Warn_On_Suspicious_Index
(Name
: Entity_Id
; X
: Node_Id
) is
3823 -- Set to lower bound for a suspicious type
3826 -- Entity for array reference
3831 function Is_Suspicious_Type
(Typ
: Entity_Id
) return Boolean;
3832 -- Tests to see if Typ is a type for which we may have a suspicious
3833 -- index, namely an unconstrained array type, whose lower bound is
3834 -- either zero or one. If so, True is returned, and Low_Bound is set
3835 -- to this lower bound. If not, False is returned, and Low_Bound is
3836 -- undefined on return.
3838 -- For now, we limit this to standard string types, so any other
3839 -- unconstrained types return False. We may change our minds on this
3840 -- later on, but strings seem the most important case.
3842 procedure Test_Suspicious_Index
;
3843 -- Test if index is of suspicious type and if so, generate warning
3845 ------------------------
3846 -- Is_Suspicious_Type --
3847 ------------------------
3849 function Is_Suspicious_Type
(Typ
: Entity_Id
) return Boolean is
3853 if Is_Array_Type
(Typ
)
3854 and then not Is_Constrained
(Typ
)
3855 and then Number_Dimensions
(Typ
) = 1
3856 and then Is_Standard_String_Type
(Typ
)
3857 and then not Has_Warnings_Off
(Typ
)
3859 LB
:= Type_Low_Bound
(Etype
(First_Index
(Typ
)));
3861 if Compile_Time_Known_Value
(LB
) then
3862 Low_Bound
:= Expr_Value
(LB
);
3863 return Low_Bound
= Uint_0
or else Low_Bound
= Uint_1
;
3868 end Is_Suspicious_Type
;
3870 ---------------------------
3871 -- Test_Suspicious_Index --
3872 ---------------------------
3874 procedure Test_Suspicious_Index
is
3876 function Length_Reference
(N
: Node_Id
) return Boolean;
3877 -- Check if node N is of the form Name'Length
3880 -- Generate first warning line
3882 procedure Warn_On_Index_Below_Lower_Bound
;
3883 -- Generate a warning on indexing the array with a literal value
3884 -- below the lower bound of the index type.
3886 procedure Warn_On_Literal_Index
;
3887 -- Generate a warning on indexing the array with a literal value
3889 ----------------------
3890 -- Length_Reference --
3891 ----------------------
3893 function Length_Reference
(N
: Node_Id
) return Boolean is
3894 R
: constant Node_Id
:= Original_Node
(N
);
3897 Nkind
(R
) = N_Attribute_Reference
3898 and then Attribute_Name
(R
) = Name_Length
3899 and then Is_Entity_Name
(Prefix
(R
))
3900 and then Entity
(Prefix
(R
)) = Ent
;
3901 end Length_Reference
;
3909 Error_Msg_Uint_1
:= Low_Bound
;
3910 Error_Msg_FE
-- CODEFIX
3911 ("?w?index for& may assume lower bound of^", X
, Ent
);
3914 -------------------------------------
3915 -- Warn_On_Index_Below_Lower_Bound --
3916 -------------------------------------
3918 procedure Warn_On_Index_Below_Lower_Bound
is
3920 if Is_Standard_String_Type
(Typ
) then
3922 (Compile_Time_Constraint_Error
3924 Msg
=> "?w?string index should be positive"));
3927 (Compile_Time_Constraint_Error
3929 Msg
=> "?w?index out of the allowed range"));
3931 end Warn_On_Index_Below_Lower_Bound
;
3933 ---------------------------
3934 -- Warn_On_Literal_Index --
3935 ---------------------------
3937 procedure Warn_On_Literal_Index
is
3941 -- Case where original form of subscript is an integer literal
3943 if Nkind
(Original_Node
(X
)) = N_Integer_Literal
then
3944 if Intval
(X
) = Low_Bound
then
3945 Error_Msg_FE
-- CODEFIX
3946 ("\?w?suggested replacement: `&''First`", X
, Ent
);
3948 Error_Msg_Uint_1
:= Intval
(X
) - Low_Bound
;
3949 Error_Msg_FE
-- CODEFIX
3950 ("\?w?suggested replacement: `&''First + ^`", X
, Ent
);
3954 -- Case where original form of subscript is more complex
3957 -- Build string X'First - 1 + expression where the expression
3958 -- is the original subscript. If the expression starts with "1
3959 -- + ", then the "- 1 + 1" is elided.
3961 Error_Msg_String
(1 .. 13) := "'First - 1 + ";
3962 Error_Msg_Strlen
:= 13;
3965 Sref
: Source_Ptr
:= Sloc
(First_Node
(Original_Node
(X
)));
3966 Tref
: constant Source_Buffer_Ptr
:=
3967 Source_Text
(Get_Source_File_Index
(Sref
));
3968 -- Tref (Sref) is used to scan the subscript
3971 -- Parentheses counter when scanning subscript
3974 -- Tref (Sref) points to start of subscript
3976 -- Elide - 1 if subscript starts with 1 +
3978 if Tref
(Sref
.. Sref
+ 2) = "1 +" then
3979 Error_Msg_Strlen
:= Error_Msg_Strlen
- 6;
3982 elsif Tref
(Sref
.. Sref
+ 1) = "1+" then
3983 Error_Msg_Strlen
:= Error_Msg_Strlen
- 6;
3987 -- Now we will copy the subscript to the string buffer
3991 -- Count parens, exit if terminating right paren. Note
3992 -- check to ignore paren appearing as character literal.
3994 if Tref
(Sref
+ 1) = '''
3996 Tref
(Sref
- 1) = '''
4000 if Tref
(Sref
) = '(' then
4002 elsif Tref
(Sref
) = ')' then
4008 -- Done if terminating double dot (slice case)
4011 and then (Tref
(Sref
.. Sref
+ 1) = ".."
4013 Tref
(Sref
.. Sref
+ 2) = " ..");
4015 -- Quit if we have hit EOF character, something wrong
4017 if Tref
(Sref
) = EOF
then
4021 -- String literals are too much of a pain to handle
4023 if Tref
(Sref
) = '"' or else Tref
(Sref
) = '%' then
4027 -- If we have a 'Range reference, then this is a case
4028 -- where we cannot easily give a replacement. Don't try.
4030 if Tref
(Sref
.. Sref
+ 4) = "range"
4031 and then Tref
(Sref
- 1) < 'A'
4032 and then Tref
(Sref
+ 5) < 'A'
4037 -- Else store next character
4039 Error_Msg_Strlen
:= Error_Msg_Strlen
+ 1;
4040 Error_Msg_String
(Error_Msg_Strlen
) := Tref
(Sref
);
4043 -- If we get more than 40 characters then the expression
4044 -- is too long to copy, or something has gone wrong. In
4045 -- either case, just skip the attempt at a suggested fix.
4047 if Error_Msg_Strlen
> 40 then
4053 -- Replacement subscript is now in string buffer
4055 Error_Msg_FE
-- CODEFIX
4056 ("\?w?suggested replacement: `&~`", Original_Node
(X
), Ent
);
4058 end Warn_On_Literal_Index
;
4060 -- Start of processing for Test_Suspicious_Index
4063 -- Nothing to do if subscript does not come from source (we don't
4064 -- want to give garbage warnings on compiler expanded code, e.g. the
4065 -- loops generated for slice assignments. Such junk warnings would
4066 -- be placed on source constructs with no subscript in sight).
4068 if not Comes_From_Source
(Original_Node
(X
)) then
4072 -- Case where subscript is a constant integer
4074 if Nkind
(X
) = N_Integer_Literal
then
4076 -- Case where subscript is lower than the lowest possible bound.
4077 -- This might be the case for example when programmers try to
4078 -- access a string at index 0, as they are used to in other
4079 -- programming languages like C.
4081 if Intval
(X
) < Low_Bound
then
4082 Warn_On_Index_Below_Lower_Bound
;
4084 Warn_On_Literal_Index
;
4087 -- Case where subscript is of the form X'Length
4089 elsif Length_Reference
(X
) then
4091 Error_Msg_Node_2
:= Ent
;
4093 ("\?w?suggest replacement of `&''Length` by `&''Last`",
4096 -- Case where subscript is of the form X'Length - expression
4098 elsif Nkind
(X
) = N_Op_Subtract
4099 and then Length_Reference
(Left_Opnd
(X
))
4102 Error_Msg_Node_2
:= Ent
;
4104 ("\?w?suggest replacement of `&''Length` by `&''Last`",
4105 Left_Opnd
(X
), Ent
);
4107 end Test_Suspicious_Index
;
4109 -- Start of processing for Warn_On_Suspicious_Index
4112 -- Only process if warnings activated
4114 if Warn_On_Assumed_Low_Bound
then
4116 -- Test if array is simple entity name
4118 if Is_Entity_Name
(Name
) then
4120 -- Test if array is parameter of unconstrained string type
4122 Ent
:= Entity
(Name
);
4126 and then Is_Suspicious_Type
(Typ
)
4127 and then not Low_Bound_Tested
(Ent
)
4129 Test_Suspicious_Index
;
4133 end Warn_On_Suspicious_Index
;
4135 -------------------------------
4136 -- Warn_On_Suspicious_Update --
4137 -------------------------------
4139 procedure Warn_On_Suspicious_Update
(N
: Node_Id
) is
4140 Par
: constant Node_Id
:= Parent
(N
);
4144 -- Only process if warnings activated
4146 if Warn_On_Suspicious_Contract
then
4147 if Nkind_In
(Par
, N_Op_Eq
, N_Op_Ne
) then
4148 if N
= Left_Opnd
(Par
) then
4149 Arg
:= Right_Opnd
(Par
);
4151 Arg
:= Left_Opnd
(Par
);
4154 if Same_Object
(Prefix
(N
), Arg
) then
4155 if Nkind
(Par
) = N_Op_Eq
then
4157 ("suspicious equality test with modified version of "
4158 & "same object?T?", Par
);
4161 ("suspicious inequality test with modified version of "
4162 & "same object?T?", Par
);
4167 end Warn_On_Suspicious_Update
;
4169 --------------------------------------
4170 -- Warn_On_Unassigned_Out_Parameter --
4171 --------------------------------------
4173 procedure Warn_On_Unassigned_Out_Parameter
4174 (Return_Node
: Node_Id
;
4175 Scope_Id
: Entity_Id
)
4181 -- Ignore if procedure or return statement does not come from source
4183 if not Comes_From_Source
(Scope_Id
)
4184 or else not Comes_From_Source
(Return_Node
)
4189 -- Loop through formals
4191 Form
:= First_Formal
(Scope_Id
);
4192 while Present
(Form
) loop
4194 -- We are only interested in OUT parameters that come from source
4195 -- and are never set in the source, and furthermore only in scalars
4196 -- since non-scalars generate too many false positives.
4198 if Ekind
(Form
) = E_Out_Parameter
4199 and then Never_Set_In_Source_Check_Spec
(Form
)
4200 and then Is_Scalar_Type
(Etype
(Form
))
4201 and then not Present
(Unset_Reference
(Form
))
4203 -- Before we issue the warning, an add ad hoc defence against the
4204 -- most common case of false positives with this warning which is
4205 -- the case where there is a Boolean OUT parameter that has been
4206 -- set, and whose meaning is "ignore the values of the other
4207 -- parameters". We can't of course reliably tell this case at
4208 -- compile time, but the following test kills a lot of false
4209 -- positives, without generating a significant number of false
4210 -- negatives (missed real warnings).
4212 Form2
:= First_Formal
(Scope_Id
);
4213 while Present
(Form2
) loop
4214 if Ekind
(Form2
) = E_Out_Parameter
4215 and then Root_Type
(Etype
(Form2
)) = Standard_Boolean
4216 and then not Never_Set_In_Source_Check_Spec
(Form2
)
4221 Next_Formal
(Form2
);
4224 -- Here all conditions are met, record possible unset reference
4226 Set_Unset_Reference
(Form
, Return_Node
);
4231 end Warn_On_Unassigned_Out_Parameter
;
4233 ---------------------------------
4234 -- Warn_On_Unreferenced_Entity --
4235 ---------------------------------
4237 procedure Warn_On_Unreferenced_Entity
4238 (Spec_E
: Entity_Id
;
4239 Body_E
: Entity_Id
:= Empty
)
4241 E
: Entity_Id
:= Spec_E
;
4244 if not Referenced_Check_Spec
(E
)
4245 and then not Has_Pragma_Unreferenced_Check_Spec
(E
)
4246 and then not Warnings_Off_Check_Spec
(E
)
4247 and then not Has_Junk_Name
(Spec_E
)
4248 and then not Is_Exported
(Spec_E
)
4253 -- Case of variable that is assigned but not read. We suppress
4254 -- the message if the variable is volatile, has an address
4255 -- clause, is aliased, or is a renaming, or is imported.
4257 if Referenced_As_LHS_Check_Spec
(E
)
4258 and then No
(Address_Clause
(E
))
4259 and then not Is_Volatile
(E
)
4261 if Warn_On_Modified_Unread
4262 and then not Is_Imported
(E
)
4263 and then not Is_Aliased
(E
)
4264 and then No
(Renamed_Object
(E
))
4266 if not Has_Pragma_Unmodified_Check_Spec
(E
) then
4267 Error_Msg_N
-- CODEFIX
4268 ("?u?variable & is assigned but never read!", E
);
4271 Set_Last_Assignment
(E
, Empty
);
4274 -- Normal case of neither assigned nor read (exclude variables
4275 -- referenced as out parameters, since we already generated
4276 -- appropriate warnings at the call point in this case).
4278 elsif not Referenced_As_Out_Parameter
(E
) then
4280 -- We suppress the message for types for which a valid
4281 -- pragma Unreferenced_Objects has been given, otherwise
4282 -- we go ahead and give the message.
4284 if not Has_Pragma_Unreferenced_Objects
(Etype
(E
)) then
4286 -- Distinguish renamed case in message
4288 if Present
(Renamed_Object
(E
))
4289 and then Comes_From_Source
(Renamed_Object
(E
))
4291 Error_Msg_N
-- CODEFIX
4292 ("?u?renamed variable & is not referenced!", E
);
4294 Error_Msg_N
-- CODEFIX
4295 ("?u?variable & is not referenced!", E
);
4301 if not Has_Pragma_Unreferenced_Objects
(Etype
(E
)) then
4302 if Present
(Renamed_Object
(E
))
4303 and then Comes_From_Source
(Renamed_Object
(E
))
4305 Error_Msg_N
-- CODEFIX
4306 ("?u?renamed constant & is not referenced!", E
);
4308 Error_Msg_N
-- CODEFIX
4309 ("?u?constant & is not referenced!", E
);
4313 when E_In_Out_Parameter
4316 -- Do not emit message for formals of a renaming, because they
4317 -- are never referenced explicitly.
4319 if Nkind
(Original_Node
(Unit_Declaration_Node
(Scope
(E
)))) /=
4320 N_Subprogram_Renaming_Declaration
4322 -- Suppress this message for an IN OUT parameter of a
4323 -- non-scalar type, since it is normal to have only an
4324 -- assignment in such a case.
4326 if Ekind
(E
) = E_In_Parameter
4327 or else not Referenced_As_LHS_Check_Spec
(E
)
4328 or else Is_Scalar_Type
(Etype
(E
))
4330 if Present
(Body_E
) then
4334 if not Is_Trivial_Subprogram
(Scope
(E
)) then
4335 Error_Msg_NE
-- CODEFIX
4336 ("?u?formal parameter & is not referenced!",
4342 when E_Out_Parameter
=>
4345 when E_Discriminant
=>
4346 Error_Msg_N
("?u?discriminant & is not referenced!", E
);
4348 when E_Named_Integer
4351 Error_Msg_N
-- CODEFIX
4352 ("?u?named number & is not referenced!", E
);
4354 when Formal_Object_Kind
=>
4355 Error_Msg_N
-- CODEFIX
4356 ("?u?formal object & is not referenced!", E
);
4358 when E_Enumeration_Literal
=>
4359 Error_Msg_N
-- CODEFIX
4360 ("?u?literal & is not referenced!", E
);
4363 Error_Msg_N
-- CODEFIX
4364 ("?u?function & is not referenced!", E
);
4367 Error_Msg_N
-- CODEFIX
4368 ("?u?procedure & is not referenced!", E
);
4371 Error_Msg_N
-- CODEFIX
4372 ("?u?package & is not referenced!", E
);
4375 Error_Msg_N
-- CODEFIX
4376 ("?u?exception & is not referenced!", E
);
4379 Error_Msg_N
-- CODEFIX
4380 ("?u?label & is not referenced!", E
);
4382 when E_Generic_Procedure
=>
4383 Error_Msg_N
-- CODEFIX
4384 ("?u?generic procedure & is never instantiated!", E
);
4386 when E_Generic_Function
=>
4387 Error_Msg_N
-- CODEFIX
4388 ("?u?generic function & is never instantiated!", E
);
4391 Error_Msg_N
-- CODEFIX
4392 ("?u?type & is not referenced!", E
);
4395 Error_Msg_N
-- CODEFIX
4396 ("?u?& is not referenced!", E
);
4399 -- Kill warnings on the entity on which the message has been posted
4400 -- (nothing is posted on out parameters because back end might be
4401 -- able to uncover an uninitialized path, and warn accordingly).
4403 if Ekind
(E
) /= E_Out_Parameter
then
4404 Set_Warnings_Off
(E
);
4407 end Warn_On_Unreferenced_Entity
;
4409 --------------------------------
4410 -- Warn_On_Useless_Assignment --
4411 --------------------------------
4413 procedure Warn_On_Useless_Assignment
4415 N
: Node_Id
:= Empty
)
4420 function Check_Ref
(N
: Node_Id
) return Traverse_Result
;
4421 -- Used to instantiate Traverse_Func. Returns Abandon if a reference to
4422 -- the entity in question is found.
4424 function Test_No_Refs
is new Traverse_Func
(Check_Ref
);
4430 function Check_Ref
(N
: Node_Id
) return Traverse_Result
is
4432 -- Check reference to our identifier. We use name equality here
4433 -- because the exception handlers have not yet been analyzed. This
4434 -- is not quite right, but it really does not matter that we fail
4435 -- to output the warning in some obscure cases of name clashes.
4437 if Nkind
(N
) = N_Identifier
and then Chars
(N
) = Chars
(Ent
) then
4444 -- Start of processing for Warn_On_Useless_Assignment
4447 -- Check if this is a case we want to warn on, a scalar or access
4448 -- variable with the last assignment field set, with warnings enabled,
4449 -- and which is not imported or exported. We also check that it is OK
4450 -- to capture the value. We are not going to capture any value, but
4451 -- the warning message depends on the same kind of conditions.
4453 if Is_Assignable
(Ent
)
4454 and then not Is_Return_Object
(Ent
)
4455 and then Present
(Last_Assignment
(Ent
))
4456 and then not Is_Imported
(Ent
)
4457 and then not Is_Exported
(Ent
)
4458 and then Safe_To_Capture_Value
(N
, Ent
)
4459 and then not Has_Pragma_Unreferenced_Check_Spec
(Ent
)
4460 and then not Has_Junk_Name
(Ent
)
4462 -- Before we issue the message, check covering exception handlers.
4463 -- Search up tree for enclosing statement sequences and handlers.
4465 P
:= Parent
(Last_Assignment
(Ent
));
4466 while Present
(P
) loop
4468 -- Something is really wrong if we don't find a handled statement
4469 -- sequence, so just suppress the warning.
4472 Set_Last_Assignment
(Ent
, Empty
);
4475 -- When we hit a package/subprogram body, issue warning and exit
4477 elsif Nkind_In
(P
, N_Entry_Body
,
4482 -- Case of assigned value never referenced
4486 LA
: constant Node_Id
:= Last_Assignment
(Ent
);
4489 -- Don't give this for OUT and IN OUT formals, since
4490 -- clearly caller may reference the assigned value. Also
4491 -- never give such warnings for internal variables. In
4492 -- either case, word the warning in a conditional way,
4493 -- because in the case of a component of a controlled
4494 -- type, the assigned value might be referenced in the
4495 -- Finalize operation, so we can't make a definitive
4496 -- statement that it's never referenced.
4498 if Ekind
(Ent
) = E_Variable
4499 and then not Is_Internal_Name
(Chars
(Ent
))
4501 -- Give appropriate message, distinguishing between
4502 -- assignment statements and out parameters.
4504 if Nkind_In
(Parent
(LA
), N_Parameter_Association
,
4505 N_Procedure_Call_Statement
)
4508 ("?m?& modified by call, but value might not be "
4509 & "referenced", LA
, Ent
);
4512 Error_Msg_NE
-- CODEFIX
4513 ("?m?possibly useless assignment to&, value "
4514 & "might not be referenced!", LA
, Ent
);
4519 -- Case of assigned value overwritten
4523 LA
: constant Node_Id
:= Last_Assignment
(Ent
);
4526 Error_Msg_Sloc
:= Sloc
(N
);
4528 -- Give appropriate message, distinguishing between
4529 -- assignment statements and out parameters.
4531 if Nkind_In
(Parent
(LA
), N_Procedure_Call_Statement
,
4532 N_Parameter_Association
)
4535 ("?m?& modified by call, but value overwritten #!",
4538 Error_Msg_NE
-- CODEFIX
4539 ("?m?useless assignment to&, value overwritten #!",
4545 -- Clear last assignment indication and we are done
4547 Set_Last_Assignment
(Ent
, Empty
);
4550 -- Enclosing handled sequence of statements
4552 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
then
4554 -- Check exception handlers present
4556 if Present
(Exception_Handlers
(P
)) then
4558 -- If we are not at the top level, we regard an inner
4559 -- exception handler as a decisive indicator that we should
4560 -- not generate the warning, since the variable in question
4561 -- may be accessed after an exception in the outer block.
4563 if not Nkind_In
(Parent
(P
), N_Entry_Body
,
4568 Set_Last_Assignment
(Ent
, Empty
);
4571 -- Otherwise we are at the outer level. An exception
4572 -- handler is significant only if it references the
4573 -- variable in question, or if the entity in question
4574 -- is an OUT or IN OUT parameter, in which case
4575 -- the caller can reference it after the exception
4576 -- handler completes.
4579 if Is_Formal
(Ent
) then
4580 Set_Last_Assignment
(Ent
, Empty
);
4584 X
:= First
(Exception_Handlers
(P
));
4585 while Present
(X
) loop
4586 if Test_No_Refs
(X
) = Abandon
then
4587 Set_Last_Assignment
(Ent
, Empty
);
4601 end Warn_On_Useless_Assignment
;
4603 ---------------------------------
4604 -- Warn_On_Useless_Assignments --
4605 ---------------------------------
4607 procedure Warn_On_Useless_Assignments
(E
: Entity_Id
) is
4611 Process_Deferred_References
;
4613 if Warn_On_Modified_Unread
4614 and then In_Extended_Main_Source_Unit
(E
)
4616 Ent
:= First_Entity
(E
);
4617 while Present
(Ent
) loop
4618 Warn_On_Useless_Assignment
(Ent
);
4622 end Warn_On_Useless_Assignments
;
4624 -----------------------------
4625 -- Warnings_Off_Check_Spec --
4626 -----------------------------
4628 function Warnings_Off_Check_Spec
(E
: Entity_Id
) return Boolean is
4630 if Is_Formal
(E
) and then Present
(Spec_Entity
(E
)) then
4632 -- Note: use of OR here instead of OR ELSE is deliberate, we want
4633 -- to mess with flags on both entities.
4635 return Has_Warnings_Off
(E
)
4637 Has_Warnings_Off
(Spec_Entity
(E
));
4640 return Has_Warnings_Off
(E
);
4642 end Warnings_Off_Check_Spec
;