1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, 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 Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Errout
; use Errout
;
31 with Expander
; use Expander
;
32 with Exp_Ch6
; use Exp_Ch6
;
33 with Exp_Util
; use Exp_Util
;
34 with Freeze
; use Freeze
;
36 with Lib
.Xref
; use Lib
.Xref
;
37 with Namet
; use Namet
;
38 with Nlists
; use Nlists
;
39 with Nmake
; use Nmake
;
41 with Restrict
; use Restrict
;
42 with Rident
; use Rident
;
43 with Rtsfind
; use Rtsfind
;
45 with Sem_Aux
; use Sem_Aux
;
46 with Sem_Case
; use Sem_Case
;
47 with Sem_Ch3
; use Sem_Ch3
;
48 with Sem_Ch6
; use Sem_Ch6
;
49 with Sem_Ch8
; use Sem_Ch8
;
50 with Sem_Disp
; use Sem_Disp
;
51 with Sem_Elab
; use Sem_Elab
;
52 with Sem_Eval
; use Sem_Eval
;
53 with Sem_Res
; use Sem_Res
;
54 with Sem_Type
; use Sem_Type
;
55 with Sem_Util
; use Sem_Util
;
56 with Sem_Warn
; use Sem_Warn
;
57 with Snames
; use Snames
;
58 with Stand
; use Stand
;
59 with Sinfo
; use Sinfo
;
60 with Targparm
; use Targparm
;
61 with Tbuild
; use Tbuild
;
62 with Uintp
; use Uintp
;
64 package body Sem_Ch5
is
66 Unblocked_Exit_Count
: Nat
:= 0;
67 -- This variable is used when processing if statements, case statements,
68 -- and block statements. It counts the number of exit points that are not
69 -- blocked by unconditional transfer instructions: for IF and CASE, these
70 -- are the branches of the conditional; for a block, they are the statement
71 -- sequence of the block, and the statement sequences of any exception
72 -- handlers that are part of the block. When processing is complete, if
73 -- this count is zero, it means that control cannot fall through the IF,
74 -- CASE or block statement. This is used for the generation of warning
75 -- messages. This variable is recursively saved on entry to processing the
76 -- construct, and restored on exit.
78 ------------------------
79 -- Analyze_Assignment --
80 ------------------------
82 procedure Analyze_Assignment
(N
: Node_Id
) is
83 Lhs
: constant Node_Id
:= Name
(N
);
84 Rhs
: constant Node_Id
:= Expression
(N
);
89 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
);
90 -- N is the node for the left hand side of an assignment, and it is not
91 -- a variable. This routine issues an appropriate diagnostic.
94 -- This is called to kill current value settings of a simple variable
95 -- on the left hand side. We call it if we find any error in analyzing
96 -- the assignment, and at the end of processing before setting any new
97 -- current values in place.
99 procedure Set_Assignment_Type
101 Opnd_Type
: in out Entity_Id
);
102 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
103 -- nominal subtype. This procedure is used to deal with cases where the
104 -- nominal subtype must be replaced by the actual subtype.
106 -------------------------------
107 -- Diagnose_Non_Variable_Lhs --
108 -------------------------------
110 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
112 -- Not worth posting another error if left hand side already flagged
113 -- as being illegal in some respect.
115 if Error_Posted
(N
) then
118 -- Some special bad cases of entity names
120 elsif Is_Entity_Name
(N
) then
122 Ent
: constant Entity_Id
:= Entity
(N
);
125 if Ekind
(Ent
) = E_In_Parameter
then
127 ("assignment to IN mode parameter not allowed", N
);
129 -- Renamings of protected private components are turned into
130 -- constants when compiling a protected function. In the case
131 -- of single protected types, the private component appears
134 elsif (Is_Prival
(Ent
)
136 (Ekind
(Current_Scope
) = E_Function
137 or else Ekind
(Enclosing_Dynamic_Scope
138 (Current_Scope
)) = E_Function
))
140 (Ekind
(Ent
) = E_Component
141 and then Is_Protected_Type
(Scope
(Ent
)))
144 ("protected function cannot modify protected object", N
);
146 elsif Ekind
(Ent
) = E_Loop_Parameter
then
148 ("assignment to loop parameter not allowed", N
);
152 ("left hand side of assignment must be a variable", N
);
156 -- For indexed components or selected components, test prefix
158 elsif Nkind
(N
) = N_Indexed_Component
then
159 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
161 -- Another special case for assignment to discriminant
163 elsif Nkind
(N
) = N_Selected_Component
then
164 if Present
(Entity
(Selector_Name
(N
)))
165 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
168 ("assignment to discriminant not allowed", N
);
170 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
174 -- If we fall through, we have no special message to issue!
176 Error_Msg_N
("left hand side of assignment must be a variable", N
);
178 end Diagnose_Non_Variable_Lhs
;
184 procedure Kill_Lhs
is
186 if Is_Entity_Name
(Lhs
) then
188 Ent
: constant Entity_Id
:= Entity
(Lhs
);
190 if Present
(Ent
) then
191 Kill_Current_Values
(Ent
);
197 -------------------------
198 -- Set_Assignment_Type --
199 -------------------------
201 procedure Set_Assignment_Type
203 Opnd_Type
: in out Entity_Id
)
206 Require_Entity
(Opnd
);
208 -- If the assignment operand is an in-out or out parameter, then we
209 -- get the actual subtype (needed for the unconstrained case). If the
210 -- operand is the actual in an entry declaration, then within the
211 -- accept statement it is replaced with a local renaming, which may
212 -- also have an actual subtype.
214 if Is_Entity_Name
(Opnd
)
215 and then (Ekind
(Entity
(Opnd
)) = E_Out_Parameter
216 or else Ekind
(Entity
(Opnd
)) =
218 or else Ekind
(Entity
(Opnd
)) =
219 E_Generic_In_Out_Parameter
221 (Ekind
(Entity
(Opnd
)) = E_Variable
222 and then Nkind
(Parent
(Entity
(Opnd
))) =
223 N_Object_Renaming_Declaration
224 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
227 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
229 -- If assignment operand is a component reference, then we get the
230 -- actual subtype of the component for the unconstrained case.
232 elsif Nkind_In
(Opnd
, N_Selected_Component
, N_Explicit_Dereference
)
233 and then not Is_Unchecked_Union
(Opnd_Type
)
235 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
237 if Present
(Decl
) then
238 Insert_Action
(N
, Decl
);
239 Mark_Rewrite_Insertion
(Decl
);
241 Opnd_Type
:= Defining_Identifier
(Decl
);
242 Set_Etype
(Opnd
, Opnd_Type
);
243 Freeze_Itype
(Opnd_Type
, N
);
245 elsif Is_Constrained
(Etype
(Opnd
)) then
246 Opnd_Type
:= Etype
(Opnd
);
249 -- For slice, use the constrained subtype created for the slice
251 elsif Nkind
(Opnd
) = N_Slice
then
252 Opnd_Type
:= Etype
(Opnd
);
254 end Set_Assignment_Type
;
256 -- Start of processing for Analyze_Assignment
259 Mark_Coextensions
(N
, Rhs
);
264 -- Ensure that we never do an assignment on a variable marked as
265 -- as Safe_To_Reevaluate.
267 pragma Assert
(not Is_Entity_Name
(Lhs
)
268 or else Ekind
(Entity
(Lhs
)) /= E_Variable
269 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
271 -- Start type analysis for assignment
275 -- In the most general case, both Lhs and Rhs can be overloaded, and we
276 -- must compute the intersection of the possible types on each side.
278 if Is_Overloaded
(Lhs
) then
285 Get_First_Interp
(Lhs
, I
, It
);
287 while Present
(It
.Typ
) loop
288 if Has_Compatible_Type
(Rhs
, It
.Typ
) then
289 if T1
/= Any_Type
then
291 -- An explicit dereference is overloaded if the prefix
292 -- is. Try to remove the ambiguity on the prefix, the
293 -- error will be posted there if the ambiguity is real.
295 if Nkind
(Lhs
) = N_Explicit_Dereference
then
298 PI1
: Interp_Index
:= 0;
304 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
306 while Present
(PIt
.Typ
) loop
307 if Is_Access_Type
(PIt
.Typ
)
308 and then Has_Compatible_Type
309 (Rhs
, Designated_Type
(PIt
.Typ
))
313 Disambiguate
(Prefix
(Lhs
),
316 if PIt
= No_Interp
then
318 ("ambiguous left-hand side"
319 & " in assignment", Lhs
);
322 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
332 Get_Next_Interp
(PI
, PIt
);
338 ("ambiguous left-hand side in assignment", Lhs
);
346 Get_Next_Interp
(I
, It
);
350 if T1
= Any_Type
then
352 ("no valid types for left-hand side for assignment", Lhs
);
358 -- The resulting assignment type is T1, so now we will resolve the left
359 -- hand side of the assignment using this determined type.
363 -- Cases where Lhs is not a variable
365 if not Is_Variable
(Lhs
) then
367 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
375 if Ada_Version
>= Ada_2005
then
377 -- Handle chains of renamings
380 while Nkind
(Ent
) in N_Has_Entity
381 and then Present
(Entity
(Ent
))
382 and then Present
(Renamed_Object
(Entity
(Ent
)))
384 Ent
:= Renamed_Object
(Entity
(Ent
));
387 if (Nkind
(Ent
) = N_Attribute_Reference
388 and then Attribute_Name
(Ent
) = Name_Priority
)
390 -- Renamings of the attribute Priority applied to protected
391 -- objects have been previously expanded into calls to the
392 -- Get_Ceiling run-time subprogram.
395 (Nkind
(Ent
) = N_Function_Call
396 and then (Entity
(Name
(Ent
)) = RTE
(RE_Get_Ceiling
)
398 Entity
(Name
(Ent
)) = RTE
(RO_PE_Get_Ceiling
)))
400 -- The enclosing subprogram cannot be a protected function
403 while not (Is_Subprogram
(S
)
404 and then Convention
(S
) = Convention_Protected
)
405 and then S
/= Standard_Standard
410 if Ekind
(S
) = E_Function
411 and then Convention
(S
) = Convention_Protected
414 ("protected function cannot modify protected object",
418 -- Changes of the ceiling priority of the protected object
419 -- are only effective if the Ceiling_Locking policy is in
420 -- effect (AARM D.5.2 (5/2)).
422 if Locking_Policy
/= 'C' then
423 Error_Msg_N
("assignment to the attribute PRIORITY has " &
425 Error_Msg_N
("\since no Locking_Policy has been " &
434 Diagnose_Non_Variable_Lhs
(Lhs
);
437 -- Error of assigning to limited type. We do however allow this in
438 -- certain cases where the front end generates the assignments.
440 elsif Is_Limited_Type
(T1
)
441 and then not Assignment_OK
(Lhs
)
442 and then not Assignment_OK
(Original_Node
(Lhs
))
443 and then not Is_Value_Type
(T1
)
445 -- CPP constructors can only be called in declarations
447 if Is_CPP_Constructor_Call
(Rhs
) then
448 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
451 ("left hand of assignment must not be limited type", Lhs
);
452 Explain_Limited_Type
(T1
, Lhs
);
456 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
457 -- abstract. This is only checked when the assignment Comes_From_Source,
458 -- because in some cases the expander generates such assignments (such
459 -- in the _assign operation for an abstract type).
461 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
463 ("target of assignment operation must not be abstract", Lhs
);
466 -- Resolution may have updated the subtype, in case the left-hand side
467 -- is a private protected component. Use the correct subtype to avoid
468 -- scoping issues in the back-end.
472 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
473 -- type. For example:
477 -- type Acc is access P.T;
480 -- with Pkg; use Acc;
481 -- procedure Example is
484 -- A.all := B.all; -- ERROR
487 if Nkind
(Lhs
) = N_Explicit_Dereference
488 and then Ekind
(T1
) = E_Incomplete_Type
490 Error_Msg_N
("invalid use of incomplete type", Lhs
);
495 -- Now we can complete the resolution of the right hand side
497 Set_Assignment_Type
(Lhs
, T1
);
500 -- This is the point at which we check for an unset reference
502 Check_Unset_Reference
(Rhs
);
503 Check_Unprotected_Access
(Lhs
, Rhs
);
505 -- Remaining steps are skipped if Rhs was syntactically in error
514 if not Covers
(T1
, T2
) then
515 Wrong_Type
(Rhs
, Etype
(Lhs
));
520 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
521 -- types, use the non-limited view if available
523 if Nkind
(Rhs
) = N_Explicit_Dereference
524 and then Ekind
(T2
) = E_Incomplete_Type
525 and then Is_Tagged_Type
(T2
)
526 and then Present
(Non_Limited_View
(T2
))
528 T2
:= Non_Limited_View
(T2
);
531 Set_Assignment_Type
(Rhs
, T2
);
533 if Total_Errors_Detected
/= 0 then
543 if T1
= Any_Type
or else T2
= Any_Type
then
548 -- If the rhs is class-wide or dynamically tagged, then require the lhs
549 -- to be class-wide. The case where the rhs is a dynamically tagged call
550 -- to a dispatching operation with a controlling access result is
551 -- excluded from this check, since the target has an access type (and
552 -- no tag propagation occurs in that case).
554 if (Is_Class_Wide_Type
(T2
)
555 or else (Is_Dynamically_Tagged
(Rhs
)
556 and then not Is_Access_Type
(T1
)))
557 and then not Is_Class_Wide_Type
(T1
)
559 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
561 elsif Is_Class_Wide_Type
(T1
)
562 and then not Is_Class_Wide_Type
(T2
)
563 and then not Is_Tag_Indeterminate
(Rhs
)
564 and then not Is_Dynamically_Tagged
(Rhs
)
566 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
569 -- Propagate the tag from a class-wide target to the rhs when the rhs
570 -- is a tag-indeterminate call.
572 if Is_Tag_Indeterminate
(Rhs
) then
573 if Is_Class_Wide_Type
(T1
) then
574 Propagate_Tag
(Lhs
, Rhs
);
576 elsif Nkind
(Rhs
) = N_Function_Call
577 and then Is_Entity_Name
(Name
(Rhs
))
578 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
581 ("call to abstract function must be dispatching", Name
(Rhs
));
583 elsif Nkind
(Rhs
) = N_Qualified_Expression
584 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
585 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
587 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
590 ("call to abstract function must be dispatching",
591 Name
(Expression
(Rhs
)));
595 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
596 -- apply an implicit conversion of the rhs to that type to force
597 -- appropriate static and run-time accessibility checks. This applies
598 -- as well to anonymous access-to-subprogram types that are component
599 -- subtypes or formal parameters.
601 if Ada_Version
>= Ada_2005
602 and then Is_Access_Type
(T1
)
604 if Is_Local_Anonymous_Access
(T1
)
605 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
607 -- Handle assignment to an Ada 2012 stand-alone object
608 -- of an anonymous access type.
610 or else (Ekind
(T1
) = E_Anonymous_Access_Type
611 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
612 N_Object_Declaration
)
615 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
616 Analyze_And_Resolve
(Rhs
, T1
);
620 -- Ada 2005 (AI-231): Assignment to not null variable
622 if Ada_Version
>= Ada_2005
623 and then Can_Never_Be_Null
(T1
)
624 and then not Assignment_OK
(Lhs
)
626 -- Case where we know the right hand side is null
628 if Known_Null
(Rhs
) then
629 Apply_Compile_Time_Constraint_Error
631 Msg
=> "(Ada 2005) null not allowed in null-excluding objects?",
632 Reason
=> CE_Null_Not_Allowed
);
634 -- We still mark this as a possible modification, that's necessary
635 -- to reset Is_True_Constant, and desirable for xref purposes.
637 Note_Possible_Modification
(Lhs
, Sure
=> True);
640 -- If we know the right hand side is non-null, then we convert to the
641 -- target type, since we don't need a run time check in that case.
643 elsif not Can_Never_Be_Null
(T2
) then
644 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
645 Analyze_And_Resolve
(Rhs
, T1
);
649 if Is_Scalar_Type
(T1
) then
650 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
652 -- For array types, verify that lengths match. If the right hand side
653 -- is a function call that has been inlined, the assignment has been
654 -- rewritten as a block, and the constraint check will be applied to the
655 -- assignment within the block.
657 elsif Is_Array_Type
(T1
)
659 (Nkind
(Rhs
) /= N_Type_Conversion
660 or else Is_Constrained
(Etype
(Rhs
)))
662 (Nkind
(Rhs
) /= N_Function_Call
663 or else Nkind
(N
) /= N_Block_Statement
)
665 -- Assignment verifies that the length of the Lsh and Rhs are equal,
666 -- but of course the indexes do not have to match. If the right-hand
667 -- side is a type conversion to an unconstrained type, a length check
668 -- is performed on the expression itself during expansion. In rare
669 -- cases, the redundant length check is computed on an index type
670 -- with a different representation, triggering incorrect code in the
673 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
676 -- Discriminant checks are applied in the course of expansion
681 -- Note: modifications of the Lhs may only be recorded after
682 -- checks have been applied.
684 Note_Possible_Modification
(Lhs
, Sure
=> True);
685 Check_Order_Dependence
;
687 -- ??? a real accessibility check is needed when ???
689 -- Post warning for redundant assignment or variable to itself
691 if Warn_On_Redundant_Constructs
693 -- We only warn for source constructs
695 and then Comes_From_Source
(N
)
697 -- Where the object is the same on both sides
699 and then Same_Object
(Lhs
, Original_Node
(Rhs
))
701 -- But exclude the case where the right side was an operation that
702 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
703 -- don't want to warn in such a case, since it is reasonable to write
704 -- such expressions especially when K is defined symbolically in some
707 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
709 if Nkind
(Lhs
) in N_Has_Entity
then
710 Error_Msg_NE
-- CODEFIX
711 ("?useless assignment of & to itself!", N
, Entity
(Lhs
));
713 Error_Msg_N
-- CODEFIX
714 ("?useless assignment of object to itself!", N
);
718 -- Check for non-allowed composite assignment
720 if not Support_Composite_Assign_On_Target
721 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
722 and then (not Has_Size_Clause
(T1
) or else Esize
(T1
) > 64)
724 Error_Msg_CRT
("composite assignment", N
);
727 -- Check elaboration warning for left side if not in elab code
729 if not In_Subprogram_Or_Concurrent_Unit
then
730 Check_Elab_Assign
(Lhs
);
733 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
734 -- assignment is a source assignment in the extended main source unit.
735 -- We are not interested in any reference information outside this
736 -- context, or in compiler generated assignment statements.
738 if Comes_From_Source
(N
)
739 and then In_Extended_Main_Source_Unit
(Lhs
)
741 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
744 -- Final step. If left side is an entity, then we may be able to reset
745 -- the current tracked values to new safe values. We only have something
746 -- to do if the left side is an entity name, and expansion has not
747 -- modified the node into something other than an assignment, and of
748 -- course we only capture values if it is safe to do so.
750 if Is_Entity_Name
(Lhs
)
751 and then Nkind
(N
) = N_Assignment_Statement
754 Ent
: constant Entity_Id
:= Entity
(Lhs
);
757 if Safe_To_Capture_Value
(N
, Ent
) then
759 -- If simple variable on left side, warn if this assignment
760 -- blots out another one (rendering it useless). We only do
761 -- this for source assignments, otherwise we can generate bogus
762 -- warnings when an assignment is rewritten as another
763 -- assignment, and gets tied up with itself.
765 if Warn_On_Modified_Unread
766 and then Is_Assignable
(Ent
)
767 and then Comes_From_Source
(N
)
768 and then In_Extended_Main_Source_Unit
(Ent
)
770 Warn_On_Useless_Assignment
(Ent
, N
);
773 -- If we are assigning an access type and the left side is an
774 -- entity, then make sure that the Is_Known_[Non_]Null flags
775 -- properly reflect the state of the entity after assignment.
777 if Is_Access_Type
(T1
) then
778 if Known_Non_Null
(Rhs
) then
779 Set_Is_Known_Non_Null
(Ent
, True);
781 elsif Known_Null
(Rhs
)
782 and then not Can_Never_Be_Null
(Ent
)
784 Set_Is_Known_Null
(Ent
, True);
787 Set_Is_Known_Null
(Ent
, False);
789 if not Can_Never_Be_Null
(Ent
) then
790 Set_Is_Known_Non_Null
(Ent
, False);
794 -- For discrete types, we may be able to set the current value
795 -- if the value is known at compile time.
797 elsif Is_Discrete_Type
(T1
)
798 and then Compile_Time_Known_Value
(Rhs
)
800 Set_Current_Value
(Ent
, Rhs
);
802 Set_Current_Value
(Ent
, Empty
);
805 -- If not safe to capture values, kill them
813 -- If assigning to an object in whole or in part, note location of
814 -- assignment in case no one references value. We only do this for
815 -- source assignments, otherwise we can generate bogus warnings when an
816 -- assignment is rewritten as another assignment, and gets tied up with
820 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
824 and then Safe_To_Capture_Value
(N
, Ent
)
825 and then Nkind
(N
) = N_Assignment_Statement
826 and then Warn_On_Modified_Unread
827 and then Is_Assignable
(Ent
)
828 and then Comes_From_Source
(N
)
829 and then In_Extended_Main_Source_Unit
(Ent
)
831 Set_Last_Assignment
(Ent
, Lhs
);
834 end Analyze_Assignment
;
836 -----------------------------
837 -- Analyze_Block_Statement --
838 -----------------------------
840 procedure Analyze_Block_Statement
(N
: Node_Id
) is
841 procedure Install_Return_Entities
(Scop
: Entity_Id
);
842 -- Install all entities of return statement scope Scop in the visibility
843 -- chain except for the return object since its entity is reused in a
846 -----------------------------
847 -- Install_Return_Entities --
848 -----------------------------
850 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
854 Id
:= First_Entity
(Scop
);
855 while Present
(Id
) loop
857 -- Do not install the return object
859 if not Ekind_In
(Id
, E_Constant
, E_Variable
)
860 or else not Is_Return_Object
(Id
)
867 end Install_Return_Entities
;
869 -- Local constants and variables
871 Decls
: constant List_Id
:= Declarations
(N
);
872 Id
: constant Node_Id
:= Identifier
(N
);
873 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
875 Is_BIP_Return_Statement
: Boolean;
877 -- Start of processing for Analyze_Block_Statement
880 -- In SPARK mode, we reject block statements. Note that the case of
881 -- block statements generated by the expander is fine.
883 if Nkind
(Original_Node
(N
)) = N_Block_Statement
then
884 Check_SPARK_Restriction
("block statement is not allowed", N
);
887 -- If no handled statement sequence is present, things are really messed
888 -- up, and we just return immediately (defence against previous errors).
894 -- Detect whether the block is actually a rewritten return statement of
895 -- a build-in-place function.
897 Is_BIP_Return_Statement
:=
899 and then Present
(Entity
(Id
))
900 and then Ekind
(Entity
(Id
)) = E_Return_Statement
901 and then Is_Build_In_Place_Function
902 (Return_Applies_To
(Entity
(Id
)));
904 -- Normal processing with HSS present
907 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
908 Ent
: Entity_Id
:= Empty
;
911 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
912 -- Recursively save value of this global, will be restored on exit
915 -- Initialize unblocked exit count for statements of begin block
916 -- plus one for each exception handler that is present.
918 Unblocked_Exit_Count
:= 1;
921 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ List_Length
(EH
);
924 -- If a label is present analyze it and mark it as referenced
930 -- An error defense. If we have an identifier, but no entity, then
931 -- something is wrong. If previous errors, then just remove the
932 -- identifier and continue, otherwise raise an exception.
935 if Total_Errors_Detected
/= 0 then
936 Set_Identifier
(N
, Empty
);
942 Set_Ekind
(Ent
, E_Block
);
943 Generate_Reference
(Ent
, N
, ' ');
944 Generate_Definition
(Ent
);
946 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
947 Set_Label_Construct
(Parent
(Ent
), N
);
952 -- If no entity set, create a label entity
955 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
956 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
960 Set_Etype
(Ent
, Standard_Void_Type
);
961 Set_Block_Node
(Ent
, Identifier
(N
));
964 -- The block served as an extended return statement. Ensure that any
965 -- entities created during the analysis and expansion of the return
966 -- object declaration are once again visible.
968 if Is_BIP_Return_Statement
then
969 Install_Return_Entities
(Ent
);
972 if Present
(Decls
) then
973 Analyze_Declarations
(Decls
);
975 Inspect_Deferred_Constant_Completion
(Decls
);
979 Process_End_Label
(HSS
, 'e', Ent
);
981 -- If exception handlers are present, then we indicate that enclosing
982 -- scopes contain a block with handlers. We only need to mark non-
988 Set_Has_Nested_Block_With_Handler
(S
);
989 exit when Is_Overloadable
(S
)
990 or else Ekind
(S
) = E_Package
991 or else Is_Generic_Unit
(S
);
996 Check_References
(Ent
);
997 Warn_On_Useless_Assignments
(Ent
);
1000 if Unblocked_Exit_Count
= 0 then
1001 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1002 Check_Unreachable_Code
(N
);
1004 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1007 end Analyze_Block_Statement
;
1009 ----------------------------
1010 -- Analyze_Case_Statement --
1011 ----------------------------
1013 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1015 Exp_Type
: Entity_Id
;
1016 Exp_Btype
: Entity_Id
;
1018 Dont_Care
: Boolean;
1019 Others_Present
: Boolean;
1021 pragma Warnings
(Off
, Last_Choice
);
1022 pragma Warnings
(Off
, Dont_Care
);
1023 -- Don't care about assigned values
1025 Statements_Analyzed
: Boolean := False;
1026 -- Set True if at least some statement sequences get analyzed. If False
1027 -- on exit, means we had a serious error that prevented full analysis of
1028 -- the case statement, and as a result it is not a good idea to output
1029 -- warning messages about unreachable code.
1031 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1032 -- Recursively save value of this global, will be restored on exit
1034 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1035 -- Error routine invoked by the generic instantiation below when the
1036 -- case statement has a non static choice.
1038 procedure Process_Statements
(Alternative
: Node_Id
);
1039 -- Analyzes all the statements associated with a case alternative.
1040 -- Needed by the generic instantiation below.
1042 package Case_Choices_Processing
is new
1043 Generic_Choices_Processing
1044 (Get_Alternatives
=> Alternatives
,
1045 Get_Choices
=> Discrete_Choices
,
1046 Process_Empty_Choice
=> No_OP
,
1047 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1048 Process_Associated_Node
=> Process_Statements
);
1049 use Case_Choices_Processing
;
1050 -- Instantiation of the generic choice processing package
1052 -----------------------------
1053 -- Non_Static_Choice_Error --
1054 -----------------------------
1056 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1058 Flag_Non_Static_Expr
1059 ("choice given in case statement is not static!", Choice
);
1060 end Non_Static_Choice_Error
;
1062 ------------------------
1063 -- Process_Statements --
1064 ------------------------
1066 procedure Process_Statements
(Alternative
: Node_Id
) is
1067 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1071 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1072 Statements_Analyzed
:= True;
1074 -- An interesting optimization. If the case statement expression
1075 -- is a simple entity, then we can set the current value within an
1076 -- alternative if the alternative has one possible value.
1080 -- when 2 | 3 => beta
1081 -- when others => gamma
1083 -- Here we know that N is initially 1 within alpha, but for beta and
1084 -- gamma, we do not know anything more about the initial value.
1086 if Is_Entity_Name
(Exp
) then
1087 Ent
:= Entity
(Exp
);
1089 if Ekind_In
(Ent
, E_Variable
,
1093 if List_Length
(Choices
) = 1
1094 and then Nkind
(First
(Choices
)) in N_Subexpr
1095 and then Compile_Time_Known_Value
(First
(Choices
))
1097 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1100 Analyze_Statements
(Statements
(Alternative
));
1102 -- After analyzing the case, set the current value to empty
1103 -- since we won't know what it is for the next alternative
1104 -- (unless reset by this same circuit), or after the case.
1106 Set_Current_Value
(Entity
(Exp
), Empty
);
1111 -- Case where expression is not an entity name of a variable
1113 Analyze_Statements
(Statements
(Alternative
));
1114 end Process_Statements
;
1116 -- Start of processing for Analyze_Case_Statement
1119 Unblocked_Exit_Count
:= 0;
1120 Exp
:= Expression
(N
);
1123 -- The expression must be of any discrete type. In rare cases, the
1124 -- expander constructs a case statement whose expression has a private
1125 -- type whose full view is discrete. This can happen when generating
1126 -- a stream operation for a variant type after the type is frozen,
1127 -- when the partial of view of the type of the discriminant is private.
1128 -- In that case, use the full view to analyze case alternatives.
1130 if not Is_Overloaded
(Exp
)
1131 and then not Comes_From_Source
(N
)
1132 and then Is_Private_Type
(Etype
(Exp
))
1133 and then Present
(Full_View
(Etype
(Exp
)))
1134 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1136 Resolve
(Exp
, Etype
(Exp
));
1137 Exp_Type
:= Full_View
(Etype
(Exp
));
1140 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1141 Exp_Type
:= Etype
(Exp
);
1144 Check_Unset_Reference
(Exp
);
1145 Exp_Btype
:= Base_Type
(Exp_Type
);
1147 -- The expression must be of a discrete type which must be determinable
1148 -- independently of the context in which the expression occurs, but
1149 -- using the fact that the expression must be of a discrete type.
1150 -- Moreover, the type this expression must not be a character literal
1151 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1153 -- If error already reported by Resolve, nothing more to do
1155 if Exp_Btype
= Any_Discrete
1156 or else Exp_Btype
= Any_Type
1160 elsif Exp_Btype
= Any_Character
then
1162 ("character literal as case expression is ambiguous", Exp
);
1165 elsif Ada_Version
= Ada_83
1166 and then (Is_Generic_Type
(Exp_Btype
)
1167 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1170 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1174 -- If the case expression is a formal object of mode in out, then treat
1175 -- it as having a nonstatic subtype by forcing use of the base type
1176 -- (which has to get passed to Check_Case_Choices below). Also use base
1177 -- type when the case expression is parenthesized.
1179 if Paren_Count
(Exp
) > 0
1180 or else (Is_Entity_Name
(Exp
)
1181 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1183 Exp_Type
:= Exp_Btype
;
1186 -- Call instantiated Analyze_Choices which does the rest of the work
1188 Analyze_Choices
(N
, Exp_Type
, Dont_Care
, Others_Present
);
1190 -- A case statement with a single OTHERS alternative is not allowed
1194 and then List_Length
(Alternatives
(N
)) = 1
1196 Check_SPARK_Restriction
1197 ("OTHERS as unique case alternative is not allowed", N
);
1200 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1201 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1204 -- If all our exits were blocked by unconditional transfers of control,
1205 -- then the entire CASE statement acts as an unconditional transfer of
1206 -- control, so treat it like one, and check unreachable code. Skip this
1207 -- test if we had serious errors preventing any statement analysis.
1209 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1210 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1211 Check_Unreachable_Code
(N
);
1213 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1216 if not Expander_Active
1217 and then Compile_Time_Known_Value
(Expression
(N
))
1218 and then Serious_Errors_Detected
= 0
1221 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1225 Alt
:= First
(Alternatives
(N
));
1226 while Present
(Alt
) loop
1227 if Alt
/= Chosen
then
1228 Remove_Warning_Messages
(Statements
(Alt
));
1235 end Analyze_Case_Statement
;
1237 ----------------------------
1238 -- Analyze_Exit_Statement --
1239 ----------------------------
1241 -- If the exit includes a name, it must be the name of a currently open
1242 -- loop. Otherwise there must be an innermost open loop on the stack, to
1243 -- which the statement implicitly refers.
1245 -- Additionally, in SPARK mode:
1247 -- The exit can only name the closest enclosing loop;
1249 -- An exit with a when clause must be directly contained in a loop;
1251 -- An exit without a when clause must be directly contained in an
1252 -- if-statement with no elsif or else, which is itself directly contained
1253 -- in a loop. The exit must be the last statement in the if-statement.
1255 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1256 Target
: constant Node_Id
:= Name
(N
);
1257 Cond
: constant Node_Id
:= Condition
(N
);
1258 Scope_Id
: Entity_Id
;
1264 Check_Unreachable_Code
(N
);
1267 if Present
(Target
) then
1269 U_Name
:= Entity
(Target
);
1271 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1272 Error_Msg_N
("invalid loop name in exit statement", N
);
1276 if Has_Loop_In_Inner_Open_Scopes
(U_Name
) then
1277 Check_SPARK_Restriction
1278 ("exit label must name the closest enclosing loop", N
);
1281 Set_Has_Exit
(U_Name
);
1288 for J
in reverse 0 .. Scope_Stack
.Last
loop
1289 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1290 Kind
:= Ekind
(Scope_Id
);
1293 and then (No
(Target
) or else Scope_Id
= U_Name
)
1295 Set_Has_Exit
(Scope_Id
);
1298 elsif Kind
= E_Block
1299 or else Kind
= E_Loop
1300 or else Kind
= E_Return_Statement
1306 ("cannot exit from program unit or accept statement", N
);
1311 -- Verify that if present the condition is a Boolean expression
1313 if Present
(Cond
) then
1314 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1315 Check_Unset_Reference
(Cond
);
1318 -- In SPARK mode, verify that the exit statement respects the SPARK
1321 if Present
(Cond
) then
1322 if Nkind
(Parent
(N
)) /= N_Loop_Statement
then
1323 Check_SPARK_Restriction
1324 ("exit with when clause must be directly in loop", N
);
1328 if Nkind
(Parent
(N
)) /= N_If_Statement
then
1329 if Nkind
(Parent
(N
)) = N_Elsif_Part
then
1330 Check_SPARK_Restriction
1331 ("exit must be in IF without ELSIF", N
);
1333 Check_SPARK_Restriction
("exit must be directly in IF", N
);
1336 elsif Nkind
(Parent
(Parent
(N
))) /= N_Loop_Statement
then
1337 Check_SPARK_Restriction
1338 ("exit must be in IF directly in loop", N
);
1340 -- First test the presence of ELSE, so that an exit in an ELSE leads
1341 -- to an error mentioning the ELSE.
1343 elsif Present
(Else_Statements
(Parent
(N
))) then
1344 Check_SPARK_Restriction
("exit must be in IF without ELSE", N
);
1346 -- An exit in an ELSIF does not reach here, as it would have been
1347 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1349 elsif Present
(Elsif_Parts
(Parent
(N
))) then
1350 Check_SPARK_Restriction
("exit must be in IF without ELSIF", N
);
1354 -- Chain exit statement to associated loop entity
1356 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1357 Set_First_Exit_Statement
(Scope_Id
, N
);
1359 -- Since the exit may take us out of a loop, any previous assignment
1360 -- statement is not useless, so clear last assignment indications. It
1361 -- is OK to keep other current values, since if the exit statement
1362 -- does not exit, then the current values are still valid.
1364 Kill_Current_Values
(Last_Assignment_Only
=> True);
1365 end Analyze_Exit_Statement
;
1367 ----------------------------
1368 -- Analyze_Goto_Statement --
1369 ----------------------------
1371 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1372 Label
: constant Node_Id
:= Name
(N
);
1373 Scope_Id
: Entity_Id
;
1374 Label_Scope
: Entity_Id
;
1375 Label_Ent
: Entity_Id
;
1378 Check_SPARK_Restriction
("goto statement is not allowed", N
);
1380 -- Actual semantic checks
1382 Check_Unreachable_Code
(N
);
1383 Kill_Current_Values
(Last_Assignment_Only
=> True);
1386 Label_Ent
:= Entity
(Label
);
1388 -- Ignore previous error
1390 if Label_Ent
= Any_Id
then
1393 -- We just have a label as the target of a goto
1395 elsif Ekind
(Label_Ent
) /= E_Label
then
1396 Error_Msg_N
("target of goto statement must be a label", Label
);
1399 -- Check that the target of the goto is reachable according to Ada
1400 -- scoping rules. Note: the special gotos we generate for optimizing
1401 -- local handling of exceptions would violate these rules, but we mark
1402 -- such gotos as analyzed when built, so this code is never entered.
1404 elsif not Reachable
(Label_Ent
) then
1405 Error_Msg_N
("target of goto statement is not reachable", Label
);
1409 -- Here if goto passes initial validity checks
1411 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1413 for J
in reverse 0 .. Scope_Stack
.Last
loop
1414 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1416 if Label_Scope
= Scope_Id
1417 or else (Ekind
(Scope_Id
) /= E_Block
1418 and then Ekind
(Scope_Id
) /= E_Loop
1419 and then Ekind
(Scope_Id
) /= E_Return_Statement
)
1421 if Scope_Id
/= Label_Scope
then
1423 ("cannot exit from program unit or accept statement", N
);
1430 raise Program_Error
;
1431 end Analyze_Goto_Statement
;
1433 --------------------------
1434 -- Analyze_If_Statement --
1435 --------------------------
1437 -- A special complication arises in the analysis of if statements
1439 -- The expander has circuitry to completely delete code that it can tell
1440 -- will not be executed (as a result of compile time known conditions). In
1441 -- the analyzer, we ensure that code that will be deleted in this manner is
1442 -- analyzed but not expanded. This is obviously more efficient, but more
1443 -- significantly, difficulties arise if code is expanded and then
1444 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1445 -- generated in deleted code must be frozen from start, because the nodes
1446 -- on which they depend will not be available at the freeze point.
1448 procedure Analyze_If_Statement
(N
: Node_Id
) is
1451 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1452 -- Recursively save value of this global, will be restored on exit
1454 Save_In_Deleted_Code
: Boolean;
1456 Del
: Boolean := False;
1457 -- This flag gets set True if a True condition has been found, which
1458 -- means that remaining ELSE/ELSIF parts are deleted.
1460 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1461 -- This is applied to either the N_If_Statement node itself or to an
1462 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1463 -- statements associated with it.
1465 -----------------------
1466 -- Analyze_Cond_Then --
1467 -----------------------
1469 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1470 Cond
: constant Node_Id
:= Condition
(Cnode
);
1471 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1474 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1475 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1476 Check_Unset_Reference
(Cond
);
1477 Set_Current_Value_Condition
(Cnode
);
1479 -- If already deleting, then just analyze then statements
1482 Analyze_Statements
(Tstm
);
1484 -- Compile time known value, not deleting yet
1486 elsif Compile_Time_Known_Value
(Cond
) then
1487 Save_In_Deleted_Code
:= In_Deleted_Code
;
1489 -- If condition is True, then analyze the THEN statements and set
1490 -- no expansion for ELSE and ELSIF parts.
1492 if Is_True
(Expr_Value
(Cond
)) then
1493 Analyze_Statements
(Tstm
);
1495 Expander_Mode_Save_And_Set
(False);
1496 In_Deleted_Code
:= True;
1498 -- If condition is False, analyze THEN with expansion off
1500 else -- Is_False (Expr_Value (Cond))
1501 Expander_Mode_Save_And_Set
(False);
1502 In_Deleted_Code
:= True;
1503 Analyze_Statements
(Tstm
);
1504 Expander_Mode_Restore
;
1505 In_Deleted_Code
:= Save_In_Deleted_Code
;
1508 -- Not known at compile time, not deleting, normal analysis
1511 Analyze_Statements
(Tstm
);
1513 end Analyze_Cond_Then
;
1515 -- Start of Analyze_If_Statement
1518 -- Initialize exit count for else statements. If there is no else part,
1519 -- this count will stay non-zero reflecting the fact that the uncovered
1520 -- else case is an unblocked exit.
1522 Unblocked_Exit_Count
:= 1;
1523 Analyze_Cond_Then
(N
);
1525 -- Now to analyze the elsif parts if any are present
1527 if Present
(Elsif_Parts
(N
)) then
1528 E
:= First
(Elsif_Parts
(N
));
1529 while Present
(E
) loop
1530 Analyze_Cond_Then
(E
);
1535 if Present
(Else_Statements
(N
)) then
1536 Analyze_Statements
(Else_Statements
(N
));
1539 -- If all our exits were blocked by unconditional transfers of control,
1540 -- then the entire IF statement acts as an unconditional transfer of
1541 -- control, so treat it like one, and check unreachable code.
1543 if Unblocked_Exit_Count
= 0 then
1544 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1545 Check_Unreachable_Code
(N
);
1547 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1551 Expander_Mode_Restore
;
1552 In_Deleted_Code
:= Save_In_Deleted_Code
;
1555 if not Expander_Active
1556 and then Compile_Time_Known_Value
(Condition
(N
))
1557 and then Serious_Errors_Detected
= 0
1559 if Is_True
(Expr_Value
(Condition
(N
))) then
1560 Remove_Warning_Messages
(Else_Statements
(N
));
1562 if Present
(Elsif_Parts
(N
)) then
1563 E
:= First
(Elsif_Parts
(N
));
1564 while Present
(E
) loop
1565 Remove_Warning_Messages
(Then_Statements
(E
));
1571 Remove_Warning_Messages
(Then_Statements
(N
));
1574 end Analyze_If_Statement
;
1576 ----------------------------------------
1577 -- Analyze_Implicit_Label_Declaration --
1578 ----------------------------------------
1580 -- An implicit label declaration is generated in the innermost enclosing
1581 -- declarative part. This is done for labels, and block and loop names.
1583 -- Note: any changes in this routine may need to be reflected in
1584 -- Analyze_Label_Entity.
1586 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
1587 Id
: constant Node_Id
:= Defining_Identifier
(N
);
1590 Set_Ekind
(Id
, E_Label
);
1591 Set_Etype
(Id
, Standard_Void_Type
);
1592 Set_Enclosing_Scope
(Id
, Current_Scope
);
1593 end Analyze_Implicit_Label_Declaration
;
1595 ------------------------------
1596 -- Analyze_Iteration_Scheme --
1597 ------------------------------
1599 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
1601 procedure Process_Bounds
(R
: Node_Id
);
1602 -- If the iteration is given by a range, create temporaries and
1603 -- assignment statements block to capture the bounds and perform
1604 -- required finalization actions in case a bound includes a function
1605 -- call that uses the temporary stack. We first pre-analyze a copy of
1606 -- the range in order to determine the expected type, and analyze and
1607 -- resolve the original bounds.
1609 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
1610 -- If the bounds are given by a 'Range reference on a function call
1611 -- that returns a controlled array, introduce an explicit declaration
1612 -- to capture the bounds, so that the function result can be finalized
1613 -- in timely fashion.
1615 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean;
1616 -- N is the node for an arbitrary construct. This function searches the
1617 -- construct N to see if any expressions within it contain function
1618 -- calls that use the secondary stack, returning True if any such call
1619 -- is found, and False otherwise.
1621 procedure Pre_Analyze_Range
(R_Copy
: Node_Id
);
1622 -- Determine expected type of range or domain of iteration of Ada 2012
1623 -- loop by analyzing separate copy. Do the analysis and resolution of
1624 -- the copy of the bound(s) with expansion disabled, to prevent the
1625 -- generation of finalization actions. This prevents memory leaks when
1626 -- the bounds contain calls to functions returning controlled arrays or
1627 -- when the domain of iteration is a container.
1629 -----------------------
1630 -- Pre_Analyze_Range --
1631 -----------------------
1633 procedure Pre_Analyze_Range
(R_Copy
: Node_Id
) is
1634 Save_Analysis
: Boolean;
1636 Save_Analysis
:= Full_Analysis
;
1637 Full_Analysis
:= False;
1638 Expander_Mode_Save_And_Set
(False);
1642 if Nkind
(R_Copy
) in N_Subexpr
1643 and then Is_Overloaded
(R_Copy
)
1646 -- Apply preference rules for range of predefined integer types,
1647 -- or diagnose true ambiguity.
1652 Found
: Entity_Id
:= Empty
;
1655 Get_First_Interp
(R_Copy
, I
, It
);
1656 while Present
(It
.Typ
) loop
1657 if Is_Discrete_Type
(It
.Typ
) then
1661 if Scope
(Found
) = Standard_Standard
then
1664 elsif Scope
(It
.Typ
) = Standard_Standard
then
1668 -- Both of them are user-defined
1671 ("ambiguous bounds in range of iteration",
1673 Error_Msg_N
("\possible interpretations:", R_Copy
);
1674 Error_Msg_NE
("\\} ", R_Copy
, Found
);
1675 Error_Msg_NE
("\\} ", R_Copy
, It
.Typ
);
1681 Get_Next_Interp
(I
, It
);
1686 if Is_Entity_Name
(R_Copy
)
1687 and then Is_Type
(Entity
(R_Copy
))
1690 -- Subtype mark in iteration scheme
1694 elsif Nkind
(R_Copy
) in N_Subexpr
then
1696 -- Expression in range, or Ada 2012 iterator
1701 Expander_Mode_Restore
;
1702 Full_Analysis
:= Save_Analysis
;
1703 end Pre_Analyze_Range
;
1705 --------------------
1706 -- Process_Bounds --
1707 --------------------
1709 procedure Process_Bounds
(R
: Node_Id
) is
1710 Loc
: constant Source_Ptr
:= Sloc
(N
);
1711 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
1712 Lo
: constant Node_Id
:= Low_Bound
(R
);
1713 Hi
: constant Node_Id
:= High_Bound
(R
);
1714 New_Lo_Bound
: Node_Id
;
1715 New_Hi_Bound
: Node_Id
;
1719 (Original_Bound
: Node_Id
;
1720 Analyzed_Bound
: Node_Id
) return Node_Id
;
1721 -- Capture value of bound and return captured value
1728 (Original_Bound
: Node_Id
;
1729 Analyzed_Bound
: Node_Id
) return Node_Id
1736 -- If the bound is a constant or an object, no need for a separate
1737 -- declaration. If the bound is the result of previous expansion
1738 -- it is already analyzed and should not be modified. Note that
1739 -- the Bound will be resolved later, if needed, as part of the
1740 -- call to Make_Index (literal bounds may need to be resolved to
1743 if Analyzed
(Original_Bound
) then
1744 return Original_Bound
;
1746 elsif Nkind_In
(Analyzed_Bound
, N_Integer_Literal
,
1747 N_Character_Literal
)
1748 or else Is_Entity_Name
(Analyzed_Bound
)
1750 Analyze_And_Resolve
(Original_Bound
, Typ
);
1751 return Original_Bound
;
1754 -- Here we need to capture the value
1756 Analyze_And_Resolve
(Original_Bound
, Typ
);
1758 -- Normally, the best approach is simply to generate a constant
1759 -- declaration that captures the bound. However, there is a nasty
1760 -- case where this is wrong. If the bound is complex, and has a
1761 -- possible use of the secondary stack, we need to generate a
1762 -- separate assignment statement to ensure the creation of a block
1763 -- which will release the secondary stack.
1765 -- We prefer the constant declaration, since it leaves us with a
1766 -- proper trace of the value, useful in optimizations that get rid
1767 -- of junk range checks.
1769 if not Has_Call_Using_Secondary_Stack
(Original_Bound
) then
1770 Force_Evaluation
(Original_Bound
);
1771 return Original_Bound
;
1774 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
1776 -- Here we make a declaration with a separate assignment
1777 -- statement, and insert before loop header.
1780 Make_Object_Declaration
(Loc
,
1781 Defining_Identifier
=> Id
,
1782 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
1785 Make_Assignment_Statement
(Loc
,
1786 Name
=> New_Occurrence_Of
(Id
, Loc
),
1787 Expression
=> Relocate_Node
(Original_Bound
));
1789 -- We must recursively clean in the relocated expression the flag
1790 -- analyzed to ensure that the expression is reanalyzed. Required
1791 -- to ensure that the transient scope is established now (because
1792 -- Establish_Transient_Scope discarded generating transient scopes
1793 -- in the analysis of the iteration scheme).
1795 Reset_Analyzed_Flags
(Expression
(Assign
));
1797 Insert_Actions
(Parent
(N
), New_List
(Decl
, Assign
));
1799 -- Now that this temporary variable is initialized we decorate it
1800 -- as safe-to-reevaluate to inform to the backend that no further
1801 -- asignment will be issued and hence it can be handled as side
1802 -- effect free. Note that this decoration must be done when the
1803 -- assignment has been analyzed because otherwise it will be
1804 -- rejected (see Analyze_Assignment).
1806 Set_Is_Safe_To_Reevaluate
(Id
);
1808 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
1810 if Nkind
(Assign
) = N_Assignment_Statement
then
1811 return Expression
(Assign
);
1813 return Original_Bound
;
1817 -- Start of processing for Process_Bounds
1820 Set_Parent
(R_Copy
, Parent
(R
));
1821 Pre_Analyze_Range
(R_Copy
);
1822 Typ
:= Etype
(R_Copy
);
1824 -- If the type of the discrete range is Universal_Integer, then the
1825 -- bound's type must be resolved to Integer, and any object used to
1826 -- hold the bound must also have type Integer, unless the literal
1827 -- bounds are constant-folded expressions with a user-defined type.
1829 if Typ
= Universal_Integer
then
1830 if Nkind
(Lo
) = N_Integer_Literal
1831 and then Present
(Etype
(Lo
))
1832 and then Scope
(Etype
(Lo
)) /= Standard_Standard
1836 elsif Nkind
(Hi
) = N_Integer_Literal
1837 and then Present
(Etype
(Hi
))
1838 and then Scope
(Etype
(Hi
)) /= Standard_Standard
1843 Typ
:= Standard_Integer
;
1849 New_Lo_Bound
:= One_Bound
(Lo
, Low_Bound
(R_Copy
));
1850 New_Hi_Bound
:= One_Bound
(Hi
, High_Bound
(R_Copy
));
1852 -- Propagate staticness to loop range itself, in case the
1853 -- corresponding subtype is static.
1855 if New_Lo_Bound
/= Lo
1856 and then Is_Static_Expression
(New_Lo_Bound
)
1858 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo_Bound
));
1861 if New_Hi_Bound
/= Hi
1862 and then Is_Static_Expression
(New_Hi_Bound
)
1864 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi_Bound
));
1868 --------------------------------------
1869 -- Check_Controlled_Array_Attribute --
1870 --------------------------------------
1872 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
1874 if Nkind
(DS
) = N_Attribute_Reference
1875 and then Is_Entity_Name
(Prefix
(DS
))
1876 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
1877 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
1880 Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
1881 and then Expander_Active
1884 Loc
: constant Source_Ptr
:= Sloc
(N
);
1885 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
1886 Indx
: constant Entity_Id
:=
1887 Base_Type
(Etype
(First_Index
(Arr
)));
1888 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
1893 Make_Subtype_Declaration
(Loc
,
1894 Defining_Identifier
=> Subt
,
1895 Subtype_Indication
=>
1896 Make_Subtype_Indication
(Loc
,
1897 Subtype_Mark
=> New_Reference_To
(Indx
, Loc
),
1899 Make_Range_Constraint
(Loc
,
1900 Relocate_Node
(DS
))));
1901 Insert_Before
(Parent
(N
), Decl
);
1905 Make_Attribute_Reference
(Loc
,
1906 Prefix
=> New_Reference_To
(Subt
, Loc
),
1907 Attribute_Name
=> Attribute_Name
(DS
)));
1911 end Check_Controlled_Array_Attribute
;
1913 ------------------------------------
1914 -- Has_Call_Using_Secondary_Stack --
1915 ------------------------------------
1917 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean is
1919 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
1920 -- Check if N is a function call which uses the secondary stack
1926 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
1929 Return_Typ
: Entity_Id
;
1932 if Nkind
(N
) = N_Function_Call
then
1935 -- Call using access to subprogram with explicit dereference
1937 if Nkind
(Nam
) = N_Explicit_Dereference
then
1938 Subp
:= Etype
(Nam
);
1943 Subp
:= Entity
(Nam
);
1946 Return_Typ
:= Etype
(Subp
);
1948 if Is_Composite_Type
(Return_Typ
)
1949 and then not Is_Constrained
(Return_Typ
)
1953 elsif Sec_Stack_Needed_For_Return
(Subp
) then
1958 -- Continue traversing the tree
1963 function Check_Calls
is new Traverse_Func
(Check_Call
);
1965 -- Start of processing for Has_Call_Using_Secondary_Stack
1968 return Check_Calls
(N
) = Abandon
;
1969 end Has_Call_Using_Secondary_Stack
;
1971 -- Start of processing for Analyze_Iteration_Scheme
1974 -- If this is a rewritten quantified expression, the iteration scheme
1975 -- has been analyzed already. Do no repeat analysis because the loop
1976 -- variable is already declared.
1978 if Analyzed
(N
) then
1982 -- For an infinite loop, there is no iteration scheme
1988 -- Iteration scheme is present
1991 Cond
: constant Node_Id
:= Condition
(N
);
1994 -- For WHILE loop, verify that the condition is a Boolean expression
1995 -- and resolve and check it.
1997 if Present
(Cond
) then
1998 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1999 Check_Unset_Reference
(Cond
);
2000 Set_Current_Value_Condition
(N
);
2003 -- For an iterator specification with "of", pre-analyze range to
2004 -- capture function calls that may require finalization actions.
2006 elsif Present
(Iterator_Specification
(N
)) then
2007 Pre_Analyze_Range
(Name
(Iterator_Specification
(N
)));
2008 Analyze_Iterator_Specification
(Iterator_Specification
(N
));
2010 -- Else we have a FOR loop
2014 LP
: constant Node_Id
:= Loop_Parameter_Specification
(N
);
2015 Id
: constant Entity_Id
:= Defining_Identifier
(LP
);
2016 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(LP
);
2023 -- We always consider the loop variable to be referenced, since
2024 -- the loop may be used just for counting purposes.
2026 Generate_Reference
(Id
, N
, ' ');
2028 -- Check for the case of loop variable hiding a local variable
2029 -- (used later on to give a nice warning if the hidden variable
2030 -- is never assigned).
2033 H
: constant Entity_Id
:= Homonym
(Id
);
2036 and then Enclosing_Dynamic_Scope
(H
) =
2037 Enclosing_Dynamic_Scope
(Id
)
2038 and then Ekind
(H
) = E_Variable
2039 and then Is_Discrete_Type
(Etype
(H
))
2041 Set_Hiding_Loop_Variable
(H
, Id
);
2045 -- Loop parameter specification must include subtype mark in
2048 if Nkind
(DS
) = N_Range
then
2049 Check_SPARK_Restriction
2050 ("loop parameter specification must include subtype mark",
2054 -- Now analyze the subtype definition. If it is a range, create
2055 -- temporaries for bounds.
2057 if Nkind
(DS
) = N_Range
2058 and then Expander_Active
2060 Process_Bounds
(DS
);
2062 -- expander not active or else range of iteration is a subtype
2063 -- indication, an entity, or a function call that yields an
2064 -- aggregate or a container.
2067 D_Copy
:= New_Copy_Tree
(DS
);
2068 Set_Parent
(D_Copy
, Parent
(DS
));
2069 Pre_Analyze_Range
(D_Copy
);
2071 -- Ada 2012: If the domain of iteration is a function call,
2072 -- it is the new iterator form.
2074 -- We have also implemented the shorter form : for X in S
2075 -- for Alfa use. In this case, 'Old and 'Result must be
2076 -- treated as entity names over which iterators are legal.
2078 if Nkind
(D_Copy
) = N_Function_Call
2081 and then (Nkind
(D_Copy
) = N_Attribute_Reference
2083 (Attribute_Name
(D_Copy
) = Name_Result
2084 or else Attribute_Name
(D_Copy
) = Name_Old
)))
2086 (Is_Entity_Name
(D_Copy
)
2087 and then not Is_Type
(Entity
(D_Copy
)))
2089 -- This is an iterator specification. Rewrite as such
2090 -- and analyze, to capture function calls that may
2091 -- require finalization actions.
2094 I_Spec
: constant Node_Id
:=
2095 Make_Iterator_Specification
(Sloc
(LP
),
2096 Defining_Identifier
=>
2099 Subtype_Indication
=> Empty
,
2101 Reverse_Present
(LP
));
2103 Set_Iterator_Specification
(N
, I_Spec
);
2104 Set_Loop_Parameter_Specification
(N
, Empty
);
2105 Analyze_Iterator_Specification
(I_Spec
);
2107 -- In a generic context, analyze the original domain
2108 -- of iteration, for name capture.
2110 if not Expander_Active
then
2114 -- Set kind of loop parameter, which may be used in
2115 -- the subsequent analysis of the condition in a
2116 -- quantified expression.
2118 Set_Ekind
(Id
, E_Loop_Parameter
);
2122 -- Domain of iteration is not a function call, and is
2123 -- side-effect free.
2134 -- Some additional checks if we are iterating through a type
2136 if Is_Entity_Name
(DS
)
2137 and then Present
(Entity
(DS
))
2138 and then Is_Type
(Entity
(DS
))
2140 -- The subtype indication may denote the completion of an
2141 -- incomplete type declaration.
2143 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
2144 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
2145 Set_Etype
(DS
, Entity
(DS
));
2148 -- Attempt to iterate through non-static predicate
2150 if Is_Discrete_Type
(Entity
(DS
))
2151 and then Present
(Predicate_Function
(Entity
(DS
)))
2152 and then No
(Static_Predicate
(Entity
(DS
)))
2154 Bad_Predicated_Subtype_Use
2155 ("cannot use subtype& with non-static "
2156 & "predicate for loop iteration", DS
, Entity
(DS
));
2160 -- Error if not discrete type
2162 if not Is_Discrete_Type
(Etype
(DS
)) then
2163 Wrong_Type
(DS
, Any_Discrete
);
2164 Set_Etype
(DS
, Any_Type
);
2167 Check_Controlled_Array_Attribute
(DS
);
2169 Make_Index
(DS
, LP
, In_Iter_Schm
=> True);
2171 Set_Ekind
(Id
, E_Loop_Parameter
);
2173 -- If the loop is part of a predicate or precondition, it may
2174 -- be analyzed twice, once in the source and once on the copy
2175 -- used to check conformance. Preserve the original itype
2176 -- because the second one may be created in a different scope,
2177 -- e.g. a precondition procedure, leading to a crash in GIGI.
2179 if No
(Etype
(Id
)) or else Etype
(Id
) = Any_Type
then
2180 Set_Etype
(Id
, Etype
(DS
));
2183 -- Treat a range as an implicit reference to the type, to
2184 -- inhibit spurious warnings.
2186 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
2187 Set_Is_Known_Valid
(Id
, True);
2189 -- The loop is not a declarative part, so the only entity
2190 -- declared "within" must be frozen explicitly.
2193 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
2195 if Is_Non_Empty_List
(Flist
) then
2196 Insert_Actions
(N
, Flist
);
2200 -- Check for null or possibly null range and issue warning. We
2201 -- suppress such messages in generic templates and instances,
2202 -- because in practice they tend to be dubious in these cases.
2204 if Nkind
(DS
) = N_Range
and then Comes_From_Source
(N
) then
2206 L
: constant Node_Id
:= Low_Bound
(DS
);
2207 H
: constant Node_Id
:= High_Bound
(DS
);
2210 -- If range of loop is null, issue warning
2212 if Compile_Time_Compare
2213 (L
, H
, Assume_Valid
=> True) = GT
2215 -- Suppress the warning if inside a generic template
2216 -- or instance, since in practice they tend to be
2217 -- dubious in these cases since they can result from
2218 -- intended parametrization.
2220 if not Inside_A_Generic
2221 and then not In_Instance
2223 -- Specialize msg if invalid values could make the
2224 -- loop non-null after all.
2226 if Compile_Time_Compare
2227 (L
, H
, Assume_Valid
=> False) = GT
2230 ("?loop range is null, loop will not execute",
2233 -- Since we know the range of the loop is null,
2234 -- set the appropriate flag to remove the loop
2235 -- entirely during expansion.
2237 Set_Is_Null_Loop
(Parent
(N
));
2239 -- Here is where the loop could execute because
2240 -- of invalid values, so issue appropriate
2241 -- message and in this case we do not set the
2242 -- Is_Null_Loop flag since the loop may execute.
2246 ("?loop range may be null, "
2247 & "loop may not execute",
2250 ("?can only execute if invalid values "
2256 -- In either case, suppress warnings in the body of
2257 -- the loop, since it is likely that these warnings
2258 -- will be inappropriate if the loop never actually
2259 -- executes, which is likely.
2261 Set_Suppress_Loop_Warnings
(Parent
(N
));
2263 -- The other case for a warning is a reverse loop
2264 -- where the upper bound is the integer literal zero
2265 -- or one, and the lower bound can be positive.
2267 -- For example, we have
2269 -- for J in reverse N .. 1 loop
2271 -- In practice, this is very likely to be a case of
2272 -- reversing the bounds incorrectly in the range.
2274 elsif Reverse_Present
(LP
)
2275 and then Nkind
(Original_Node
(H
)) =
2277 and then (Intval
(Original_Node
(H
)) = Uint_0
2279 Intval
(Original_Node
(H
)) = Uint_1
)
2281 Error_Msg_N
("?loop range may be null", DS
);
2282 Error_Msg_N
("\?bounds may be wrong way round", DS
);
2289 end Analyze_Iteration_Scheme
;
2291 -------------------------------------
2292 -- Analyze_Iterator_Specification --
2293 -------------------------------------
2295 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
2296 Loc
: constant Source_Ptr
:= Sloc
(N
);
2297 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
2298 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
2299 Iter_Name
: constant Node_Id
:= Name
(N
);
2305 -- In semantics/Alfa modes, we won't be further expanding the loop, so
2306 -- introduce loop variable so that loop body can be properly analyzed.
2307 -- Otherwise this happens after expansion.
2309 if Operating_Mode
= Check_Semantics
2312 Enter_Name
(Def_Id
);
2315 Set_Ekind
(Def_Id
, E_Variable
);
2317 if Present
(Subt
) then
2321 -- If domain of iteration is an expression, create a declaration for
2322 -- it, so that finalization actions are introduced outside of the loop.
2323 -- The declaration must be a renaming because the body of the loop may
2324 -- assign to elements.
2326 if not Is_Entity_Name
(Iter_Name
) then
2328 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
2332 Typ
:= Etype
(Iter_Name
);
2335 Make_Object_Renaming_Declaration
(Loc
,
2336 Defining_Identifier
=> Id
,
2337 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
2338 Name
=> Relocate_Node
(Iter_Name
));
2340 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
2341 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
2342 Set_Etype
(Id
, Typ
);
2343 Set_Etype
(Name
(N
), Typ
);
2346 -- Container is an entity or an array with uncontrolled components, or
2347 -- else it is a container iterator given by a function call, typically
2348 -- called Iterate in the case of predefined containers, even though
2349 -- Iterate is not a reserved name. What matter is that the return type
2350 -- of the function is an iterator type.
2353 Analyze
(Iter_Name
);
2355 if Nkind
(Iter_Name
) = N_Function_Call
then
2357 C
: constant Node_Id
:= Name
(Iter_Name
);
2362 if not Is_Overloaded
(Iter_Name
) then
2363 Resolve
(Iter_Name
, Etype
(C
));
2366 Get_First_Interp
(C
, I
, It
);
2367 while It
.Typ
/= Empty
loop
2368 if Reverse_Present
(N
) then
2369 if Is_Reversible_Iterator
(It
.Typ
) then
2370 Resolve
(Iter_Name
, It
.Typ
);
2374 elsif Is_Iterator
(It
.Typ
) then
2375 Resolve
(Iter_Name
, It
.Typ
);
2379 Get_Next_Interp
(I
, It
);
2384 -- Domain of iteration is not overloaded
2387 Resolve
(Iter_Name
, Etype
(Iter_Name
));
2391 Typ
:= Etype
(Iter_Name
);
2393 if Is_Array_Type
(Typ
) then
2394 if Of_Present
(N
) then
2395 Set_Etype
(Def_Id
, Component_Type
(Typ
));
2397 -- Here we have a missing Range attribute
2401 ("missing Range attribute in iteration over an array", N
);
2403 -- In Ada 2012 mode, this may be an attempt at an iterator
2405 if Ada_Version
>= Ada_2012
then
2407 ("\if& is meant to designate an element of the array, use OF",
2411 -- Prevent cascaded errors
2413 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2414 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2417 -- Check for type error in iterator
2419 elsif Typ
= Any_Type
then
2422 -- Iteration over a container
2425 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2427 if Of_Present
(N
) then
2429 -- The type of the loop variable is the Iterator_Element aspect of
2430 -- the container type.
2433 Entity
(Find_Aspect
(Typ
, Aspect_Iterator_Element
)));
2436 -- For an iteration of the form IN, the name must denote an
2437 -- iterator, typically the result of a call to Iterate. Give a
2438 -- useful error message when the name is a container by itself.
2440 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2441 and then not Is_Iterator
(Typ
)
2444 ("name must be an iterator, not a container", Name
(N
));
2447 ("\to iterate directly over a container, write `of &`",
2448 Name
(N
), Original_Node
(Name
(N
)));
2451 -- The result type of Iterate function is the classwide type of
2452 -- the interface parent. We need the specific Cursor type defined
2453 -- in the container package.
2455 Ent
:= First_Entity
(Scope
(Typ
));
2456 while Present
(Ent
) loop
2457 if Chars
(Ent
) = Name_Cursor
then
2458 Set_Etype
(Def_Id
, Etype
(Ent
));
2466 end Analyze_Iterator_Specification
;
2472 -- Note: the semantic work required for analyzing labels (setting them as
2473 -- reachable) was done in a prepass through the statements in the block,
2474 -- so that forward gotos would be properly handled. See Analyze_Statements
2475 -- for further details. The only processing required here is to deal with
2476 -- optimizations that depend on an assumption of sequential control flow,
2477 -- since of course the occurrence of a label breaks this assumption.
2479 procedure Analyze_Label
(N
: Node_Id
) is
2480 pragma Warnings
(Off
, N
);
2482 Kill_Current_Values
;
2485 --------------------------
2486 -- Analyze_Label_Entity --
2487 --------------------------
2489 procedure Analyze_Label_Entity
(E
: Entity_Id
) is
2491 Set_Ekind
(E
, E_Label
);
2492 Set_Etype
(E
, Standard_Void_Type
);
2493 Set_Enclosing_Scope
(E
, Current_Scope
);
2494 Set_Reachable
(E
, True);
2495 end Analyze_Label_Entity
;
2497 ----------------------------
2498 -- Analyze_Loop_Statement --
2499 ----------------------------
2501 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
2502 Loop_Statement
: constant Node_Id
:= N
;
2504 Id
: constant Node_Id
:= Identifier
(Loop_Statement
);
2505 Iter
: constant Node_Id
:= Iteration_Scheme
(Loop_Statement
);
2509 if Present
(Id
) then
2511 -- Make name visible, e.g. for use in exit statements. Loop labels
2512 -- are always considered to be referenced.
2517 -- Guard against serious error (typically, a scope mismatch when
2518 -- semantic analysis is requested) by creating loop entity to
2519 -- continue analysis.
2522 if Total_Errors_Detected
/= 0 then
2525 (E_Loop
, Current_Scope
, Sloc
(Loop_Statement
), 'L');
2527 raise Program_Error
;
2531 Generate_Reference
(Ent
, Loop_Statement
, ' ');
2532 Generate_Definition
(Ent
);
2534 -- If we found a label, mark its type. If not, ignore it, since it
2535 -- means we have a conflicting declaration, which would already
2536 -- have been diagnosed at declaration time. Set Label_Construct
2537 -- of the implicit label declaration, which is not created by the
2538 -- parser for generic units.
2540 if Ekind
(Ent
) = E_Label
then
2541 Set_Ekind
(Ent
, E_Loop
);
2543 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
2544 Set_Label_Construct
(Parent
(Ent
), Loop_Statement
);
2549 -- Case of no identifier present
2554 (E_Loop
, Current_Scope
, Sloc
(Loop_Statement
), 'L');
2555 Set_Etype
(Ent
, Standard_Void_Type
);
2556 Set_Parent
(Ent
, Loop_Statement
);
2559 -- Kill current values on entry to loop, since statements in the body of
2560 -- the loop may have been executed before the loop is entered. Similarly
2561 -- we kill values after the loop, since we do not know that the body of
2562 -- the loop was executed.
2564 Kill_Current_Values
;
2566 Analyze_Iteration_Scheme
(Iter
);
2568 -- Analyze the statements of the body except in the case of an Ada 2012
2569 -- iterator with the expander active. In this case the expander will do
2570 -- a rewrite of the loop into a while loop. We will then analyze the
2571 -- loop body when we analyze this while loop.
2573 -- We need to do this delay because if the container is for indefinite
2574 -- types the actual subtype of the components will only be determined
2575 -- when the cursor declaration is analyzed.
2577 -- If the expander is not active, then we want to analyze the loop body
2578 -- now even in the Ada 2012 iterator case, since the rewriting will not
2579 -- be done. Insert the loop variable in the current scope, if not done
2580 -- when analysing the iteration scheme.
2583 or else No
(Iterator_Specification
(Iter
))
2584 or else not Expander_Active
2587 and then Present
(Iterator_Specification
(Iter
))
2590 Id
: constant Entity_Id
:=
2591 Defining_Identifier
(Iterator_Specification
(Iter
));
2593 if Scope
(Id
) /= Current_Scope
then
2599 Analyze_Statements
(Statements
(Loop_Statement
));
2602 -- Finish up processing for the loop. We kill all current values, since
2603 -- in general we don't know if the statements in the loop have been
2604 -- executed. We could do a bit better than this with a loop that we
2605 -- know will execute at least once, but it's not worth the trouble and
2606 -- the front end is not in the business of flow tracing.
2608 Process_End_Label
(Loop_Statement
, 'e', Ent
);
2610 Kill_Current_Values
;
2612 -- Check for infinite loop. Skip check for generated code, since it
2613 -- justs waste time and makes debugging the routine called harder.
2615 -- Note that we have to wait till the body of the loop is fully analyzed
2616 -- before making this call, since Check_Infinite_Loop_Warning relies on
2617 -- being able to use semantic visibility information to find references.
2619 if Comes_From_Source
(N
) then
2620 Check_Infinite_Loop_Warning
(N
);
2623 -- Code after loop is unreachable if the loop has no WHILE or FOR and
2624 -- contains no EXIT statements within the body of the loop.
2626 if No
(Iter
) and then not Has_Exit
(Ent
) then
2627 Check_Unreachable_Code
(N
);
2629 end Analyze_Loop_Statement
;
2631 ----------------------------
2632 -- Analyze_Null_Statement --
2633 ----------------------------
2635 -- Note: the semantics of the null statement is implemented by a single
2636 -- null statement, too bad everything isn't as simple as this!
2638 procedure Analyze_Null_Statement
(N
: Node_Id
) is
2639 pragma Warnings
(Off
, N
);
2642 end Analyze_Null_Statement
;
2644 ------------------------
2645 -- Analyze_Statements --
2646 ------------------------
2648 procedure Analyze_Statements
(L
: List_Id
) is
2653 -- The labels declared in the statement list are reachable from
2654 -- statements in the list. We do this as a prepass so that any goto
2655 -- statement will be properly flagged if its target is not reachable.
2656 -- This is not required, but is nice behavior!
2659 while Present
(S
) loop
2660 if Nkind
(S
) = N_Label
then
2661 Analyze
(Identifier
(S
));
2662 Lab
:= Entity
(Identifier
(S
));
2664 -- If we found a label mark it as reachable
2666 if Ekind
(Lab
) = E_Label
then
2667 Generate_Definition
(Lab
);
2668 Set_Reachable
(Lab
);
2670 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
2671 Set_Label_Construct
(Parent
(Lab
), S
);
2674 -- If we failed to find a label, it means the implicit declaration
2675 -- of the label was hidden. A for-loop parameter can do this to
2676 -- a label with the same name inside the loop, since the implicit
2677 -- label declaration is in the innermost enclosing body or block
2681 Error_Msg_Sloc
:= Sloc
(Lab
);
2683 ("implicit label declaration for & is hidden#",
2691 -- Perform semantic analysis on all statements
2693 Conditional_Statements_Begin
;
2696 while Present
(S
) loop
2701 Conditional_Statements_End
;
2703 -- Make labels unreachable. Visibility is not sufficient, because labels
2704 -- in one if-branch for example are not reachable from the other branch,
2705 -- even though their declarations are in the enclosing declarative part.
2708 while Present
(S
) loop
2709 if Nkind
(S
) = N_Label
then
2710 Set_Reachable
(Entity
(Identifier
(S
)), False);
2715 end Analyze_Statements
;
2717 ----------------------------
2718 -- Check_Unreachable_Code --
2719 ----------------------------
2721 procedure Check_Unreachable_Code
(N
: Node_Id
) is
2722 Error_Node
: Node_Id
;
2726 if Is_List_Member
(N
)
2727 and then Comes_From_Source
(N
)
2733 Nxt
:= Original_Node
(Next
(N
));
2735 -- If a label follows us, then we never have dead code, since
2736 -- someone could branch to the label, so we just ignore it, unless
2737 -- we are in formal mode where goto statements are not allowed.
2739 if Nkind
(Nxt
) = N_Label
2740 and then not Restriction_Check_Required
(SPARK
)
2744 -- Otherwise see if we have a real statement following us
2747 and then Comes_From_Source
(Nxt
)
2748 and then Is_Statement
(Nxt
)
2750 -- Special very annoying exception. If we have a return that
2751 -- follows a raise, then we allow it without a warning, since
2752 -- the Ada RM annoyingly requires a useless return here!
2754 if Nkind
(Original_Node
(N
)) /= N_Raise_Statement
2755 or else Nkind
(Nxt
) /= N_Simple_Return_Statement
2757 -- The rather strange shenanigans with the warning message
2758 -- here reflects the fact that Kill_Dead_Code is very good
2759 -- at removing warnings in deleted code, and this is one
2760 -- warning we would prefer NOT to have removed.
2764 -- If we have unreachable code, analyze and remove the
2765 -- unreachable code, since it is useless and we don't
2766 -- want to generate junk warnings.
2768 -- We skip this step if we are not in code generation mode.
2769 -- This is the one case where we remove dead code in the
2770 -- semantics as opposed to the expander, and we do not want
2771 -- to remove code if we are not in code generation mode,
2772 -- since this messes up the ASIS trees.
2774 -- Note that one might react by moving the whole circuit to
2775 -- exp_ch5, but then we lose the warning in -gnatc mode.
2777 if Operating_Mode
= Generate_Code
then
2781 -- Quit deleting when we have nothing more to delete
2782 -- or if we hit a label (since someone could transfer
2783 -- control to a label, so we should not delete it).
2785 exit when No
(Nxt
) or else Nkind
(Nxt
) = N_Label
;
2787 -- Statement/declaration is to be deleted
2791 Kill_Dead_Code
(Nxt
);
2795 -- Now issue the warning (or error in formal mode)
2797 if Restriction_Check_Required
(SPARK
) then
2798 Check_SPARK_Restriction
2799 ("unreachable code is not allowed", Error_Node
);
2801 Error_Msg
("?unreachable code!", Sloc
(Error_Node
));
2805 -- If the unconditional transfer of control instruction is the
2806 -- last statement of a sequence, then see if our parent is one of
2807 -- the constructs for which we count unblocked exits, and if so,
2808 -- adjust the count.
2813 -- Statements in THEN part or ELSE part of IF statement
2815 if Nkind
(P
) = N_If_Statement
then
2818 -- Statements in ELSIF part of an IF statement
2820 elsif Nkind
(P
) = N_Elsif_Part
then
2822 pragma Assert
(Nkind
(P
) = N_If_Statement
);
2824 -- Statements in CASE statement alternative
2826 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
2828 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
2830 -- Statements in body of block
2832 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
2833 and then Nkind
(Parent
(P
)) = N_Block_Statement
2837 -- Statements in exception handler in a block
2839 elsif Nkind
(P
) = N_Exception_Handler
2840 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
2841 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
2845 -- None of these cases, so return
2851 -- This was one of the cases we are looking for (i.e. the
2852 -- parent construct was IF, CASE or block) so decrement count.
2854 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
2858 end Check_Unreachable_Code
;