1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2015, 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_Ch7
; use Exp_Ch7
;
34 with Exp_Util
; use Exp_Util
;
35 with Freeze
; use Freeze
;
36 with Ghost
; use Ghost
;
38 with Lib
.Xref
; use Lib
.Xref
;
39 with Namet
; use Namet
;
40 with Nlists
; use Nlists
;
41 with Nmake
; use Nmake
;
43 with Restrict
; use Restrict
;
44 with Rident
; use Rident
;
45 with Rtsfind
; use Rtsfind
;
47 with Sem_Aux
; use Sem_Aux
;
48 with Sem_Case
; use Sem_Case
;
49 with Sem_Ch3
; use Sem_Ch3
;
50 with Sem_Ch6
; use Sem_Ch6
;
51 with Sem_Ch8
; use Sem_Ch8
;
52 with Sem_Dim
; use Sem_Dim
;
53 with Sem_Disp
; use Sem_Disp
;
54 with Sem_Elab
; use Sem_Elab
;
55 with Sem_Eval
; use Sem_Eval
;
56 with Sem_Res
; use Sem_Res
;
57 with Sem_Type
; use Sem_Type
;
58 with Sem_Util
; use Sem_Util
;
59 with Sem_Warn
; use Sem_Warn
;
60 with Snames
; use Snames
;
61 with Stand
; use Stand
;
62 with Sinfo
; use Sinfo
;
63 with Targparm
; use Targparm
;
64 with Tbuild
; use Tbuild
;
65 with Uintp
; use Uintp
;
67 package body Sem_Ch5
is
69 Unblocked_Exit_Count
: Nat
:= 0;
70 -- This variable is used when processing if statements, case statements,
71 -- and block statements. It counts the number of exit points that are not
72 -- blocked by unconditional transfer instructions: for IF and CASE, these
73 -- are the branches of the conditional; for a block, they are the statement
74 -- sequence of the block, and the statement sequences of any exception
75 -- handlers that are part of the block. When processing is complete, if
76 -- this count is zero, it means that control cannot fall through the IF,
77 -- CASE or block statement. This is used for the generation of warning
78 -- messages. This variable is recursively saved on entry to processing the
79 -- construct, and restored on exit.
81 procedure Preanalyze_Range
(R_Copy
: Node_Id
);
82 -- Determine expected type of range or domain of iteration of Ada 2012
83 -- loop by analyzing separate copy. Do the analysis and resolution of the
84 -- copy of the bound(s) with expansion disabled, to prevent the generation
85 -- of finalization actions. This prevents memory leaks when the bounds
86 -- contain calls to functions returning controlled arrays or when the
87 -- domain of iteration is a container.
89 ------------------------
90 -- Analyze_Assignment --
91 ------------------------
93 procedure Analyze_Assignment
(N
: Node_Id
) is
94 Lhs
: constant Node_Id
:= Name
(N
);
95 Rhs
: constant Node_Id
:= Expression
(N
);
100 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
);
101 -- N is the node for the left hand side of an assignment, and it is not
102 -- a variable. This routine issues an appropriate diagnostic.
105 -- This is called to kill current value settings of a simple variable
106 -- on the left hand side. We call it if we find any error in analyzing
107 -- the assignment, and at the end of processing before setting any new
108 -- current values in place.
110 procedure Set_Assignment_Type
112 Opnd_Type
: in out Entity_Id
);
113 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
114 -- nominal subtype. This procedure is used to deal with cases where the
115 -- nominal subtype must be replaced by the actual subtype.
117 -------------------------------
118 -- Diagnose_Non_Variable_Lhs --
119 -------------------------------
121 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
123 -- Not worth posting another error if left hand side already flagged
124 -- as being illegal in some respect.
126 if Error_Posted
(N
) then
129 -- Some special bad cases of entity names
131 elsif Is_Entity_Name
(N
) then
133 Ent
: constant Entity_Id
:= Entity
(N
);
136 if Ekind
(Ent
) = E_In_Parameter
then
138 ("assignment to IN mode parameter not allowed", N
);
141 -- Renamings of protected private components are turned into
142 -- constants when compiling a protected function. In the case
143 -- of single protected types, the private component appears
146 elsif (Is_Prival
(Ent
)
148 (Ekind
(Current_Scope
) = E_Function
149 or else Ekind
(Enclosing_Dynamic_Scope
150 (Current_Scope
)) = E_Function
))
152 (Ekind
(Ent
) = E_Component
153 and then Is_Protected_Type
(Scope
(Ent
)))
156 ("protected function cannot modify protected object", N
);
159 elsif Ekind
(Ent
) = E_Loop_Parameter
then
160 Error_Msg_N
("assignment to loop parameter not allowed", N
);
165 -- For indexed components, test prefix if it is in array. We do not
166 -- want to recurse for cases where the prefix is a pointer, since we
167 -- may get a message confusing the pointer and what it references.
169 elsif Nkind
(N
) = N_Indexed_Component
170 and then Is_Array_Type
(Etype
(Prefix
(N
)))
172 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
175 -- Another special case for assignment to discriminant
177 elsif Nkind
(N
) = N_Selected_Component
then
178 if Present
(Entity
(Selector_Name
(N
)))
179 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
181 Error_Msg_N
("assignment to discriminant not allowed", N
);
184 -- For selection from record, diagnose prefix, but note that again
185 -- we only do this for a record, not e.g. for a pointer.
187 elsif Is_Record_Type
(Etype
(Prefix
(N
))) then
188 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
193 -- If we fall through, we have no special message to issue
195 Error_Msg_N
("left hand side of assignment must be a variable", N
);
196 end Diagnose_Non_Variable_Lhs
;
202 procedure Kill_Lhs
is
204 if Is_Entity_Name
(Lhs
) then
206 Ent
: constant Entity_Id
:= Entity
(Lhs
);
208 if Present
(Ent
) then
209 Kill_Current_Values
(Ent
);
215 -------------------------
216 -- Set_Assignment_Type --
217 -------------------------
219 procedure Set_Assignment_Type
221 Opnd_Type
: in out Entity_Id
)
224 Require_Entity
(Opnd
);
226 -- If the assignment operand is an in-out or out parameter, then we
227 -- get the actual subtype (needed for the unconstrained case). If the
228 -- operand is the actual in an entry declaration, then within the
229 -- accept statement it is replaced with a local renaming, which may
230 -- also have an actual subtype.
232 if Is_Entity_Name
(Opnd
)
233 and then (Ekind
(Entity
(Opnd
)) = E_Out_Parameter
234 or else Ekind_In
(Entity
(Opnd
),
236 E_Generic_In_Out_Parameter
)
238 (Ekind
(Entity
(Opnd
)) = E_Variable
239 and then Nkind
(Parent
(Entity
(Opnd
))) =
240 N_Object_Renaming_Declaration
241 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
244 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
246 -- If assignment operand is a component reference, then we get the
247 -- actual subtype of the component for the unconstrained case.
249 elsif Nkind_In
(Opnd
, N_Selected_Component
, N_Explicit_Dereference
)
250 and then not Is_Unchecked_Union
(Opnd_Type
)
252 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
254 if Present
(Decl
) then
255 Insert_Action
(N
, Decl
);
256 Mark_Rewrite_Insertion
(Decl
);
258 Opnd_Type
:= Defining_Identifier
(Decl
);
259 Set_Etype
(Opnd
, Opnd_Type
);
260 Freeze_Itype
(Opnd_Type
, N
);
262 elsif Is_Constrained
(Etype
(Opnd
)) then
263 Opnd_Type
:= Etype
(Opnd
);
266 -- For slice, use the constrained subtype created for the slice
268 elsif Nkind
(Opnd
) = N_Slice
then
269 Opnd_Type
:= Etype
(Opnd
);
271 end Set_Assignment_Type
;
275 Save_Ghost_Mode
: constant Ghost_Mode_Type
:= Ghost_Mode
;
277 -- Start of processing for Analyze_Assignment
280 Mark_Coextensions
(N
, Rhs
);
282 -- Analyze the target of the assignment first in case the expression
283 -- contains references to Ghost entities. The checks that verify the
284 -- proper use of a Ghost entity need to know the enclosing context.
288 -- An assignment statement is Ghost when the left hand side denotes a
289 -- Ghost entity. Set the mode now to ensure that any nodes generated
290 -- during analysis and expansion are properly marked as Ghost.
295 -- Ensure that we never do an assignment on a variable marked as
296 -- as Safe_To_Reevaluate.
298 pragma Assert
(not Is_Entity_Name
(Lhs
)
299 or else Ekind
(Entity
(Lhs
)) /= E_Variable
300 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
302 -- Start type analysis for assignment
306 -- In the most general case, both Lhs and Rhs can be overloaded, and we
307 -- must compute the intersection of the possible types on each side.
309 if Is_Overloaded
(Lhs
) then
316 Get_First_Interp
(Lhs
, I
, It
);
318 while Present
(It
.Typ
) loop
320 -- An indexed component with generalized indexing is always
321 -- overloaded with the corresponding dereference. Discard the
322 -- interpretation that yields a reference type, which is not
325 if Nkind
(Lhs
) = N_Indexed_Component
326 and then Present
(Generalized_Indexing
(Lhs
))
327 and then Has_Implicit_Dereference
(It
.Typ
)
331 elsif Has_Compatible_Type
(Rhs
, It
.Typ
) then
332 if T1
/= Any_Type
then
334 -- An explicit dereference is overloaded if the prefix
335 -- is. Try to remove the ambiguity on the prefix, the
336 -- error will be posted there if the ambiguity is real.
338 if Nkind
(Lhs
) = N_Explicit_Dereference
then
341 PI1
: Interp_Index
:= 0;
347 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
349 while Present
(PIt
.Typ
) loop
350 if Is_Access_Type
(PIt
.Typ
)
351 and then Has_Compatible_Type
352 (Rhs
, Designated_Type
(PIt
.Typ
))
356 Disambiguate
(Prefix
(Lhs
),
359 if PIt
= No_Interp
then
361 ("ambiguous left-hand side"
362 & " in assignment", Lhs
);
365 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
375 Get_Next_Interp
(PI
, PIt
);
381 ("ambiguous left-hand side in assignment", Lhs
);
389 Get_Next_Interp
(I
, It
);
393 if T1
= Any_Type
then
395 ("no valid types for left-hand side for assignment", Lhs
);
397 Ghost_Mode
:= Save_Ghost_Mode
;
402 -- The resulting assignment type is T1, so now we will resolve the left
403 -- hand side of the assignment using this determined type.
407 -- Cases where Lhs is not a variable
409 -- Cases where Lhs is not a variable. In an instance or an inlined body
410 -- no need for further check because assignment was legal in template.
412 if In_Inlined_Body
then
415 elsif not Is_Variable
(Lhs
) then
417 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
425 if Ada_Version
>= Ada_2005
then
427 -- Handle chains of renamings
430 while Nkind
(Ent
) in N_Has_Entity
431 and then Present
(Entity
(Ent
))
432 and then Present
(Renamed_Object
(Entity
(Ent
)))
434 Ent
:= Renamed_Object
(Entity
(Ent
));
437 if (Nkind
(Ent
) = N_Attribute_Reference
438 and then Attribute_Name
(Ent
) = Name_Priority
)
440 -- Renamings of the attribute Priority applied to protected
441 -- objects have been previously expanded into calls to the
442 -- Get_Ceiling run-time subprogram.
445 (Nkind
(Ent
) = N_Function_Call
446 and then (Entity
(Name
(Ent
)) = RTE
(RE_Get_Ceiling
)
448 Entity
(Name
(Ent
)) = RTE
(RO_PE_Get_Ceiling
)))
450 -- The enclosing subprogram cannot be a protected function
453 while not (Is_Subprogram
(S
)
454 and then Convention
(S
) = Convention_Protected
)
455 and then S
/= Standard_Standard
460 if Ekind
(S
) = E_Function
461 and then Convention
(S
) = Convention_Protected
464 ("protected function cannot modify protected object",
468 -- Changes of the ceiling priority of the protected object
469 -- are only effective if the Ceiling_Locking policy is in
470 -- effect (AARM D.5.2 (5/2)).
472 if Locking_Policy
/= 'C' then
473 Error_Msg_N
("assignment to the attribute PRIORITY has " &
475 Error_Msg_N
("\since no Locking_Policy has been " &
479 Ghost_Mode
:= Save_Ghost_Mode
;
485 Diagnose_Non_Variable_Lhs
(Lhs
);
486 Ghost_Mode
:= Save_Ghost_Mode
;
489 -- Error of assigning to limited type. We do however allow this in
490 -- certain cases where the front end generates the assignments.
492 elsif Is_Limited_Type
(T1
)
493 and then not Assignment_OK
(Lhs
)
494 and then not Assignment_OK
(Original_Node
(Lhs
))
496 -- CPP constructors can only be called in declarations
498 if Is_CPP_Constructor_Call
(Rhs
) then
499 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
502 ("left hand of assignment must not be limited type", Lhs
);
503 Explain_Limited_Type
(T1
, Lhs
);
506 Ghost_Mode
:= Save_Ghost_Mode
;
509 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
510 -- abstract. This is only checked when the assignment Comes_From_Source,
511 -- because in some cases the expander generates such assignments (such
512 -- in the _assign operation for an abstract type).
514 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
516 ("target of assignment operation must not be abstract", Lhs
);
519 -- Resolution may have updated the subtype, in case the left-hand side
520 -- is a private protected component. Use the correct subtype to avoid
521 -- scoping issues in the back-end.
525 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
526 -- type. For example:
530 -- type Acc is access P.T;
533 -- with Pkg; use Acc;
534 -- procedure Example is
537 -- A.all := B.all; -- ERROR
540 if Nkind
(Lhs
) = N_Explicit_Dereference
541 and then Ekind
(T1
) = E_Incomplete_Type
543 Error_Msg_N
("invalid use of incomplete type", Lhs
);
545 Ghost_Mode
:= Save_Ghost_Mode
;
549 -- Now we can complete the resolution of the right hand side
551 Set_Assignment_Type
(Lhs
, T1
);
554 -- This is the point at which we check for an unset reference
556 Check_Unset_Reference
(Rhs
);
557 Check_Unprotected_Access
(Lhs
, Rhs
);
559 -- Remaining steps are skipped if Rhs was syntactically in error
563 Ghost_Mode
:= Save_Ghost_Mode
;
569 if not Covers
(T1
, T2
) then
570 Wrong_Type
(Rhs
, Etype
(Lhs
));
572 Ghost_Mode
:= Save_Ghost_Mode
;
576 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
577 -- types, use the non-limited view if available
579 if Nkind
(Rhs
) = N_Explicit_Dereference
580 and then Is_Tagged_Type
(T2
)
581 and then Has_Non_Limited_View
(T2
)
583 T2
:= Non_Limited_View
(T2
);
586 Set_Assignment_Type
(Rhs
, T2
);
588 if Total_Errors_Detected
/= 0 then
598 if T1
= Any_Type
or else T2
= Any_Type
then
600 Ghost_Mode
:= Save_Ghost_Mode
;
604 -- If the rhs is class-wide or dynamically tagged, then require the lhs
605 -- to be class-wide. The case where the rhs is a dynamically tagged call
606 -- to a dispatching operation with a controlling access result is
607 -- excluded from this check, since the target has an access type (and
608 -- no tag propagation occurs in that case).
610 if (Is_Class_Wide_Type
(T2
)
611 or else (Is_Dynamically_Tagged
(Rhs
)
612 and then not Is_Access_Type
(T1
)))
613 and then not Is_Class_Wide_Type
(T1
)
615 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
617 elsif Is_Class_Wide_Type
(T1
)
618 and then not Is_Class_Wide_Type
(T2
)
619 and then not Is_Tag_Indeterminate
(Rhs
)
620 and then not Is_Dynamically_Tagged
(Rhs
)
622 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
625 -- Propagate the tag from a class-wide target to the rhs when the rhs
626 -- is a tag-indeterminate call.
628 if Is_Tag_Indeterminate
(Rhs
) then
629 if Is_Class_Wide_Type
(T1
) then
630 Propagate_Tag
(Lhs
, Rhs
);
632 elsif Nkind
(Rhs
) = N_Function_Call
633 and then Is_Entity_Name
(Name
(Rhs
))
634 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
637 ("call to abstract function must be dispatching", Name
(Rhs
));
639 elsif Nkind
(Rhs
) = N_Qualified_Expression
640 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
641 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
643 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
646 ("call to abstract function must be dispatching",
647 Name
(Expression
(Rhs
)));
651 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
652 -- apply an implicit conversion of the rhs to that type to force
653 -- appropriate static and run-time accessibility checks. This applies
654 -- as well to anonymous access-to-subprogram types that are component
655 -- subtypes or formal parameters.
657 if Ada_Version
>= Ada_2005
and then Is_Access_Type
(T1
) then
658 if Is_Local_Anonymous_Access
(T1
)
659 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
661 -- Handle assignment to an Ada 2012 stand-alone object
662 -- of an anonymous access type.
664 or else (Ekind
(T1
) = E_Anonymous_Access_Type
665 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
666 N_Object_Declaration
)
669 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
670 Analyze_And_Resolve
(Rhs
, T1
);
674 -- Ada 2005 (AI-231): Assignment to not null variable
676 if Ada_Version
>= Ada_2005
677 and then Can_Never_Be_Null
(T1
)
678 and then not Assignment_OK
(Lhs
)
680 -- Case where we know the right hand side is null
682 if Known_Null
(Rhs
) then
683 Apply_Compile_Time_Constraint_Error
686 "(Ada 2005) null not allowed in null-excluding objects??",
687 Reason
=> CE_Null_Not_Allowed
);
689 -- We still mark this as a possible modification, that's necessary
690 -- to reset Is_True_Constant, and desirable for xref purposes.
692 Note_Possible_Modification
(Lhs
, Sure
=> True);
693 Ghost_Mode
:= Save_Ghost_Mode
;
696 -- If we know the right hand side is non-null, then we convert to the
697 -- target type, since we don't need a run time check in that case.
699 elsif not Can_Never_Be_Null
(T2
) then
700 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
701 Analyze_And_Resolve
(Rhs
, T1
);
705 if Is_Scalar_Type
(T1
) then
706 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
708 -- For array types, verify that lengths match. If the right hand side
709 -- is a function call that has been inlined, the assignment has been
710 -- rewritten as a block, and the constraint check will be applied to the
711 -- assignment within the block.
713 elsif Is_Array_Type
(T1
)
714 and then (Nkind
(Rhs
) /= N_Type_Conversion
715 or else Is_Constrained
(Etype
(Rhs
)))
716 and then (Nkind
(Rhs
) /= N_Function_Call
717 or else Nkind
(N
) /= N_Block_Statement
)
719 -- Assignment verifies that the length of the Lsh and Rhs are equal,
720 -- but of course the indexes do not have to match. If the right-hand
721 -- side is a type conversion to an unconstrained type, a length check
722 -- is performed on the expression itself during expansion. In rare
723 -- cases, the redundant length check is computed on an index type
724 -- with a different representation, triggering incorrect code in the
727 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
730 -- Discriminant checks are applied in the course of expansion
735 -- Note: modifications of the Lhs may only be recorded after
736 -- checks have been applied.
738 Note_Possible_Modification
(Lhs
, Sure
=> True);
740 -- ??? a real accessibility check is needed when ???
742 -- Post warning for redundant assignment or variable to itself
744 if Warn_On_Redundant_Constructs
746 -- We only warn for source constructs
748 and then Comes_From_Source
(N
)
750 -- Where the object is the same on both sides
752 and then Same_Object
(Lhs
, Original_Node
(Rhs
))
754 -- But exclude the case where the right side was an operation that
755 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
756 -- don't want to warn in such a case, since it is reasonable to write
757 -- such expressions especially when K is defined symbolically in some
760 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
762 if Nkind
(Lhs
) in N_Has_Entity
then
763 Error_Msg_NE
-- CODEFIX
764 ("?r?useless assignment of & to itself!", N
, Entity
(Lhs
));
766 Error_Msg_N
-- CODEFIX
767 ("?r?useless assignment of object to itself!", N
);
771 -- Check for non-allowed composite assignment
773 if not Support_Composite_Assign_On_Target
774 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
775 and then (not Has_Size_Clause
(T1
) or else Esize
(T1
) > 64)
777 Error_Msg_CRT
("composite assignment", N
);
780 -- Check elaboration warning for left side if not in elab code
782 if not In_Subprogram_Or_Concurrent_Unit
then
783 Check_Elab_Assign
(Lhs
);
786 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
787 -- assignment is a source assignment in the extended main source unit.
788 -- We are not interested in any reference information outside this
789 -- context, or in compiler generated assignment statements.
791 if Comes_From_Source
(N
)
792 and then In_Extended_Main_Source_Unit
(Lhs
)
794 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
797 -- RM 7.3.2 (12/3) An assignment to a view conversion (from a type
798 -- to one of its ancestors) requires an invariant check. Apply check
799 -- only if expression comes from source, otherwise it will be applied
800 -- when value is assigned to source entity.
802 if Nkind
(Lhs
) = N_Type_Conversion
803 and then Has_Invariants
(Etype
(Expression
(Lhs
)))
804 and then Comes_From_Source
(Expression
(Lhs
))
806 Insert_After
(N
, Make_Invariant_Call
(Expression
(Lhs
)));
809 -- Final step. If left side is an entity, then we may be able to reset
810 -- the current tracked values to new safe values. We only have something
811 -- to do if the left side is an entity name, and expansion has not
812 -- modified the node into something other than an assignment, and of
813 -- course we only capture values if it is safe to do so.
815 if Is_Entity_Name
(Lhs
)
816 and then Nkind
(N
) = N_Assignment_Statement
819 Ent
: constant Entity_Id
:= Entity
(Lhs
);
822 if Safe_To_Capture_Value
(N
, Ent
) then
824 -- If simple variable on left side, warn if this assignment
825 -- blots out another one (rendering it useless). We only do
826 -- this for source assignments, otherwise we can generate bogus
827 -- warnings when an assignment is rewritten as another
828 -- assignment, and gets tied up with itself.
830 if Warn_On_Modified_Unread
831 and then Is_Assignable
(Ent
)
832 and then Comes_From_Source
(N
)
833 and then In_Extended_Main_Source_Unit
(Ent
)
835 Warn_On_Useless_Assignment
(Ent
, N
);
838 -- If we are assigning an access type and the left side is an
839 -- entity, then make sure that the Is_Known_[Non_]Null flags
840 -- properly reflect the state of the entity after assignment.
842 if Is_Access_Type
(T1
) then
843 if Known_Non_Null
(Rhs
) then
844 Set_Is_Known_Non_Null
(Ent
, True);
846 elsif Known_Null
(Rhs
)
847 and then not Can_Never_Be_Null
(Ent
)
849 Set_Is_Known_Null
(Ent
, True);
852 Set_Is_Known_Null
(Ent
, False);
854 if not Can_Never_Be_Null
(Ent
) then
855 Set_Is_Known_Non_Null
(Ent
, False);
859 -- For discrete types, we may be able to set the current value
860 -- if the value is known at compile time.
862 elsif Is_Discrete_Type
(T1
)
863 and then Compile_Time_Known_Value
(Rhs
)
865 Set_Current_Value
(Ent
, Rhs
);
867 Set_Current_Value
(Ent
, Empty
);
870 -- If not safe to capture values, kill them
878 -- If assigning to an object in whole or in part, note location of
879 -- assignment in case no one references value. We only do this for
880 -- source assignments, otherwise we can generate bogus warnings when an
881 -- assignment is rewritten as another assignment, and gets tied up with
885 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
888 and then Safe_To_Capture_Value
(N
, Ent
)
889 and then Nkind
(N
) = N_Assignment_Statement
890 and then Warn_On_Modified_Unread
891 and then Is_Assignable
(Ent
)
892 and then Comes_From_Source
(N
)
893 and then In_Extended_Main_Source_Unit
(Ent
)
895 Set_Last_Assignment
(Ent
, Lhs
);
899 Analyze_Dimension
(N
);
900 Ghost_Mode
:= Save_Ghost_Mode
;
901 end Analyze_Assignment
;
903 -----------------------------
904 -- Analyze_Block_Statement --
905 -----------------------------
907 procedure Analyze_Block_Statement
(N
: Node_Id
) is
908 procedure Install_Return_Entities
(Scop
: Entity_Id
);
909 -- Install all entities of return statement scope Scop in the visibility
910 -- chain except for the return object since its entity is reused in a
913 -----------------------------
914 -- Install_Return_Entities --
915 -----------------------------
917 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
921 Id
:= First_Entity
(Scop
);
922 while Present
(Id
) loop
924 -- Do not install the return object
926 if not Ekind_In
(Id
, E_Constant
, E_Variable
)
927 or else not Is_Return_Object
(Id
)
934 end Install_Return_Entities
;
936 -- Local constants and variables
938 Decls
: constant List_Id
:= Declarations
(N
);
939 Id
: constant Node_Id
:= Identifier
(N
);
940 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
942 Is_BIP_Return_Statement
: Boolean;
944 -- Start of processing for Analyze_Block_Statement
947 -- In SPARK mode, we reject block statements. Note that the case of
948 -- block statements generated by the expander is fine.
950 if Nkind
(Original_Node
(N
)) = N_Block_Statement
then
951 Check_SPARK_05_Restriction
("block statement is not allowed", N
);
954 -- If no handled statement sequence is present, things are really messed
955 -- up, and we just return immediately (defence against previous errors).
958 Check_Error_Detected
;
962 -- Detect whether the block is actually a rewritten return statement of
963 -- a build-in-place function.
965 Is_BIP_Return_Statement
:=
967 and then Present
(Entity
(Id
))
968 and then Ekind
(Entity
(Id
)) = E_Return_Statement
969 and then Is_Build_In_Place_Function
970 (Return_Applies_To
(Entity
(Id
)));
972 -- Normal processing with HSS present
975 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
976 Ent
: Entity_Id
:= Empty
;
979 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
980 -- Recursively save value of this global, will be restored on exit
983 -- Initialize unblocked exit count for statements of begin block
984 -- plus one for each exception handler that is present.
986 Unblocked_Exit_Count
:= 1;
989 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ List_Length
(EH
);
992 -- If a label is present analyze it and mark it as referenced
998 -- An error defense. If we have an identifier, but no entity, then
999 -- something is wrong. If previous errors, then just remove the
1000 -- identifier and continue, otherwise raise an exception.
1003 Check_Error_Detected
;
1004 Set_Identifier
(N
, Empty
);
1007 Set_Ekind
(Ent
, E_Block
);
1008 Generate_Reference
(Ent
, N
, ' ');
1009 Generate_Definition
(Ent
);
1011 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
1012 Set_Label_Construct
(Parent
(Ent
), N
);
1017 -- If no entity set, create a label entity
1020 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
1021 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
1022 Set_Parent
(Ent
, N
);
1025 Set_Etype
(Ent
, Standard_Void_Type
);
1026 Set_Block_Node
(Ent
, Identifier
(N
));
1029 -- The block served as an extended return statement. Ensure that any
1030 -- entities created during the analysis and expansion of the return
1031 -- object declaration are once again visible.
1033 if Is_BIP_Return_Statement
then
1034 Install_Return_Entities
(Ent
);
1037 if Present
(Decls
) then
1038 Analyze_Declarations
(Decls
);
1040 Inspect_Deferred_Constant_Completion
(Decls
);
1044 Process_End_Label
(HSS
, 'e', Ent
);
1046 -- If exception handlers are present, then we indicate that enclosing
1047 -- scopes contain a block with handlers. We only need to mark non-
1050 if Present
(EH
) then
1053 Set_Has_Nested_Block_With_Handler
(S
);
1054 exit when Is_Overloadable
(S
)
1055 or else Ekind
(S
) = E_Package
1056 or else Is_Generic_Unit
(S
);
1061 Check_References
(Ent
);
1062 Warn_On_Useless_Assignments
(Ent
);
1065 if Unblocked_Exit_Count
= 0 then
1066 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1067 Check_Unreachable_Code
(N
);
1069 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1072 end Analyze_Block_Statement
;
1074 --------------------------------
1075 -- Analyze_Compound_Statement --
1076 --------------------------------
1078 procedure Analyze_Compound_Statement
(N
: Node_Id
) is
1080 Analyze_List
(Actions
(N
));
1081 end Analyze_Compound_Statement
;
1083 ----------------------------
1084 -- Analyze_Case_Statement --
1085 ----------------------------
1087 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1089 Exp_Type
: Entity_Id
;
1090 Exp_Btype
: Entity_Id
;
1093 Others_Present
: Boolean;
1094 -- Indicates if Others was present
1096 pragma Warnings
(Off
, Last_Choice
);
1097 -- Don't care about assigned value
1099 Statements_Analyzed
: Boolean := False;
1100 -- Set True if at least some statement sequences get analyzed. If False
1101 -- on exit, means we had a serious error that prevented full analysis of
1102 -- the case statement, and as a result it is not a good idea to output
1103 -- warning messages about unreachable code.
1105 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1106 -- Recursively save value of this global, will be restored on exit
1108 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1109 -- Error routine invoked by the generic instantiation below when the
1110 -- case statement has a non static choice.
1112 procedure Process_Statements
(Alternative
: Node_Id
);
1113 -- Analyzes the statements associated with a case alternative. Needed
1114 -- by instantiation below.
1116 package Analyze_Case_Choices
is new
1117 Generic_Analyze_Choices
1118 (Process_Associated_Node
=> Process_Statements
);
1119 use Analyze_Case_Choices
;
1120 -- Instantiation of the generic choice analysis package
1122 package Check_Case_Choices
is new
1123 Generic_Check_Choices
1124 (Process_Empty_Choice
=> No_OP
,
1125 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1126 Process_Associated_Node
=> No_OP
);
1127 use Check_Case_Choices
;
1128 -- Instantiation of the generic choice processing package
1130 -----------------------------
1131 -- Non_Static_Choice_Error --
1132 -----------------------------
1134 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1136 Flag_Non_Static_Expr
1137 ("choice given in case statement is not static!", Choice
);
1138 end Non_Static_Choice_Error
;
1140 ------------------------
1141 -- Process_Statements --
1142 ------------------------
1144 procedure Process_Statements
(Alternative
: Node_Id
) is
1145 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1149 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1150 Statements_Analyzed
:= True;
1152 -- An interesting optimization. If the case statement expression
1153 -- is a simple entity, then we can set the current value within an
1154 -- alternative if the alternative has one possible value.
1158 -- when 2 | 3 => beta
1159 -- when others => gamma
1161 -- Here we know that N is initially 1 within alpha, but for beta and
1162 -- gamma, we do not know anything more about the initial value.
1164 if Is_Entity_Name
(Exp
) then
1165 Ent
:= Entity
(Exp
);
1167 if Ekind_In
(Ent
, E_Variable
,
1171 if List_Length
(Choices
) = 1
1172 and then Nkind
(First
(Choices
)) in N_Subexpr
1173 and then Compile_Time_Known_Value
(First
(Choices
))
1175 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1178 Analyze_Statements
(Statements
(Alternative
));
1180 -- After analyzing the case, set the current value to empty
1181 -- since we won't know what it is for the next alternative
1182 -- (unless reset by this same circuit), or after the case.
1184 Set_Current_Value
(Entity
(Exp
), Empty
);
1189 -- Case where expression is not an entity name of a variable
1191 Analyze_Statements
(Statements
(Alternative
));
1192 end Process_Statements
;
1194 -- Start of processing for Analyze_Case_Statement
1197 Unblocked_Exit_Count
:= 0;
1198 Exp
:= Expression
(N
);
1201 -- The expression must be of any discrete type. In rare cases, the
1202 -- expander constructs a case statement whose expression has a private
1203 -- type whose full view is discrete. This can happen when generating
1204 -- a stream operation for a variant type after the type is frozen,
1205 -- when the partial of view of the type of the discriminant is private.
1206 -- In that case, use the full view to analyze case alternatives.
1208 if not Is_Overloaded
(Exp
)
1209 and then not Comes_From_Source
(N
)
1210 and then Is_Private_Type
(Etype
(Exp
))
1211 and then Present
(Full_View
(Etype
(Exp
)))
1212 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1214 Resolve
(Exp
, Etype
(Exp
));
1215 Exp_Type
:= Full_View
(Etype
(Exp
));
1218 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1219 Exp_Type
:= Etype
(Exp
);
1222 Check_Unset_Reference
(Exp
);
1223 Exp_Btype
:= Base_Type
(Exp_Type
);
1225 -- The expression must be of a discrete type which must be determinable
1226 -- independently of the context in which the expression occurs, but
1227 -- using the fact that the expression must be of a discrete type.
1228 -- Moreover, the type this expression must not be a character literal
1229 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1231 -- If error already reported by Resolve, nothing more to do
1233 if Exp_Btype
= Any_Discrete
or else Exp_Btype
= Any_Type
then
1236 elsif Exp_Btype
= Any_Character
then
1238 ("character literal as case expression is ambiguous", Exp
);
1241 elsif Ada_Version
= Ada_83
1242 and then (Is_Generic_Type
(Exp_Btype
)
1243 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1246 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1250 -- If the case expression is a formal object of mode in out, then treat
1251 -- it as having a nonstatic subtype by forcing use of the base type
1252 -- (which has to get passed to Check_Case_Choices below). Also use base
1253 -- type when the case expression is parenthesized.
1255 if Paren_Count
(Exp
) > 0
1256 or else (Is_Entity_Name
(Exp
)
1257 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1259 Exp_Type
:= Exp_Btype
;
1262 -- Call instantiated procedures to analyzwe and check discrete choices
1264 Analyze_Choices
(Alternatives
(N
), Exp_Type
);
1265 Check_Choices
(N
, Alternatives
(N
), Exp_Type
, Others_Present
);
1267 -- Case statement with single OTHERS alternative not allowed in SPARK
1269 if Others_Present
and then List_Length
(Alternatives
(N
)) = 1 then
1270 Check_SPARK_05_Restriction
1271 ("OTHERS as unique case alternative is not allowed", N
);
1274 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1275 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1278 -- If all our exits were blocked by unconditional transfers of control,
1279 -- then the entire CASE statement acts as an unconditional transfer of
1280 -- control, so treat it like one, and check unreachable code. Skip this
1281 -- test if we had serious errors preventing any statement analysis.
1283 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1284 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1285 Check_Unreachable_Code
(N
);
1287 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1290 -- If the expander is active it will detect the case of a statically
1291 -- determined single alternative and remove warnings for the case, but
1292 -- if we are not doing expansion, that circuit won't be active. Here we
1293 -- duplicate the effect of removing warnings in the same way, so that
1294 -- we will get the same set of warnings in -gnatc mode.
1296 if not Expander_Active
1297 and then Compile_Time_Known_Value
(Expression
(N
))
1298 and then Serious_Errors_Detected
= 0
1301 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1305 Alt
:= First
(Alternatives
(N
));
1306 while Present
(Alt
) loop
1307 if Alt
/= Chosen
then
1308 Remove_Warning_Messages
(Statements
(Alt
));
1315 end Analyze_Case_Statement
;
1317 ----------------------------
1318 -- Analyze_Exit_Statement --
1319 ----------------------------
1321 -- If the exit includes a name, it must be the name of a currently open
1322 -- loop. Otherwise there must be an innermost open loop on the stack, to
1323 -- which the statement implicitly refers.
1325 -- Additionally, in SPARK mode:
1327 -- The exit can only name the closest enclosing loop;
1329 -- An exit with a when clause must be directly contained in a loop;
1331 -- An exit without a when clause must be directly contained in an
1332 -- if-statement with no elsif or else, which is itself directly contained
1333 -- in a loop. The exit must be the last statement in the if-statement.
1335 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1336 Target
: constant Node_Id
:= Name
(N
);
1337 Cond
: constant Node_Id
:= Condition
(N
);
1338 Scope_Id
: Entity_Id
;
1344 Check_Unreachable_Code
(N
);
1347 if Present
(Target
) then
1349 U_Name
:= Entity
(Target
);
1351 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1352 Error_Msg_N
("invalid loop name in exit statement", N
);
1356 if Has_Loop_In_Inner_Open_Scopes
(U_Name
) then
1357 Check_SPARK_05_Restriction
1358 ("exit label must name the closest enclosing loop", N
);
1361 Set_Has_Exit
(U_Name
);
1368 for J
in reverse 0 .. Scope_Stack
.Last
loop
1369 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1370 Kind
:= Ekind
(Scope_Id
);
1372 if Kind
= E_Loop
and then (No
(Target
) or else Scope_Id
= U_Name
) then
1373 Set_Has_Exit
(Scope_Id
);
1376 elsif Kind
= E_Block
1377 or else Kind
= E_Loop
1378 or else Kind
= E_Return_Statement
1384 ("cannot exit from program unit or accept statement", N
);
1389 -- Verify that if present the condition is a Boolean expression
1391 if Present
(Cond
) then
1392 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1393 Check_Unset_Reference
(Cond
);
1396 -- In SPARK mode, verify that the exit statement respects the SPARK
1399 if Present
(Cond
) then
1400 if Nkind
(Parent
(N
)) /= N_Loop_Statement
then
1401 Check_SPARK_05_Restriction
1402 ("exit with when clause must be directly in loop", N
);
1406 if Nkind
(Parent
(N
)) /= N_If_Statement
then
1407 if Nkind
(Parent
(N
)) = N_Elsif_Part
then
1408 Check_SPARK_05_Restriction
1409 ("exit must be in IF without ELSIF", N
);
1411 Check_SPARK_05_Restriction
("exit must be directly in IF", N
);
1414 elsif Nkind
(Parent
(Parent
(N
))) /= N_Loop_Statement
then
1415 Check_SPARK_05_Restriction
1416 ("exit must be in IF directly in loop", N
);
1418 -- First test the presence of ELSE, so that an exit in an ELSE leads
1419 -- to an error mentioning the ELSE.
1421 elsif Present
(Else_Statements
(Parent
(N
))) then
1422 Check_SPARK_05_Restriction
("exit must be in IF without ELSE", N
);
1424 -- An exit in an ELSIF does not reach here, as it would have been
1425 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1427 elsif Present
(Elsif_Parts
(Parent
(N
))) then
1428 Check_SPARK_05_Restriction
("exit must be in IF without ELSIF", N
);
1432 -- Chain exit statement to associated loop entity
1434 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1435 Set_First_Exit_Statement
(Scope_Id
, N
);
1437 -- Since the exit may take us out of a loop, any previous assignment
1438 -- statement is not useless, so clear last assignment indications. It
1439 -- is OK to keep other current values, since if the exit statement
1440 -- does not exit, then the current values are still valid.
1442 Kill_Current_Values
(Last_Assignment_Only
=> True);
1443 end Analyze_Exit_Statement
;
1445 ----------------------------
1446 -- Analyze_Goto_Statement --
1447 ----------------------------
1449 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1450 Label
: constant Node_Id
:= Name
(N
);
1451 Scope_Id
: Entity_Id
;
1452 Label_Scope
: Entity_Id
;
1453 Label_Ent
: Entity_Id
;
1456 Check_SPARK_05_Restriction
("goto statement is not allowed", N
);
1458 -- Actual semantic checks
1460 Check_Unreachable_Code
(N
);
1461 Kill_Current_Values
(Last_Assignment_Only
=> True);
1464 Label_Ent
:= Entity
(Label
);
1466 -- Ignore previous error
1468 if Label_Ent
= Any_Id
then
1469 Check_Error_Detected
;
1472 -- We just have a label as the target of a goto
1474 elsif Ekind
(Label_Ent
) /= E_Label
then
1475 Error_Msg_N
("target of goto statement must be a label", Label
);
1478 -- Check that the target of the goto is reachable according to Ada
1479 -- scoping rules. Note: the special gotos we generate for optimizing
1480 -- local handling of exceptions would violate these rules, but we mark
1481 -- such gotos as analyzed when built, so this code is never entered.
1483 elsif not Reachable
(Label_Ent
) then
1484 Error_Msg_N
("target of goto statement is not reachable", Label
);
1488 -- Here if goto passes initial validity checks
1490 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1492 for J
in reverse 0 .. Scope_Stack
.Last
loop
1493 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1495 if Label_Scope
= Scope_Id
1496 or else not Ekind_In
(Scope_Id
, E_Block
, E_Loop
, E_Return_Statement
)
1498 if Scope_Id
/= Label_Scope
then
1500 ("cannot exit from program unit or accept statement", N
);
1507 raise Program_Error
;
1508 end Analyze_Goto_Statement
;
1510 --------------------------
1511 -- Analyze_If_Statement --
1512 --------------------------
1514 -- A special complication arises in the analysis of if statements
1516 -- The expander has circuitry to completely delete code that it can tell
1517 -- will not be executed (as a result of compile time known conditions). In
1518 -- the analyzer, we ensure that code that will be deleted in this manner
1519 -- is analyzed but not expanded. This is obviously more efficient, but
1520 -- more significantly, difficulties arise if code is expanded and then
1521 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1522 -- generated in deleted code must be frozen from start, because the nodes
1523 -- on which they depend will not be available at the freeze point.
1525 procedure Analyze_If_Statement
(N
: Node_Id
) is
1528 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1529 -- Recursively save value of this global, will be restored on exit
1531 Save_In_Deleted_Code
: Boolean;
1533 Del
: Boolean := False;
1534 -- This flag gets set True if a True condition has been found, which
1535 -- means that remaining ELSE/ELSIF parts are deleted.
1537 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1538 -- This is applied to either the N_If_Statement node itself or to an
1539 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1540 -- statements associated with it.
1542 -----------------------
1543 -- Analyze_Cond_Then --
1544 -----------------------
1546 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1547 Cond
: constant Node_Id
:= Condition
(Cnode
);
1548 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1551 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1552 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1553 Check_Unset_Reference
(Cond
);
1554 Set_Current_Value_Condition
(Cnode
);
1556 -- If already deleting, then just analyze then statements
1559 Analyze_Statements
(Tstm
);
1561 -- Compile time known value, not deleting yet
1563 elsif Compile_Time_Known_Value
(Cond
) then
1564 Save_In_Deleted_Code
:= In_Deleted_Code
;
1566 -- If condition is True, then analyze the THEN statements and set
1567 -- no expansion for ELSE and ELSIF parts.
1569 if Is_True
(Expr_Value
(Cond
)) then
1570 Analyze_Statements
(Tstm
);
1572 Expander_Mode_Save_And_Set
(False);
1573 In_Deleted_Code
:= True;
1575 -- If condition is False, analyze THEN with expansion off
1577 else -- Is_False (Expr_Value (Cond))
1578 Expander_Mode_Save_And_Set
(False);
1579 In_Deleted_Code
:= True;
1580 Analyze_Statements
(Tstm
);
1581 Expander_Mode_Restore
;
1582 In_Deleted_Code
:= Save_In_Deleted_Code
;
1585 -- Not known at compile time, not deleting, normal analysis
1588 Analyze_Statements
(Tstm
);
1590 end Analyze_Cond_Then
;
1592 -- Start of processing for Analyze_If_Statement
1595 -- Initialize exit count for else statements. If there is no else part,
1596 -- this count will stay non-zero reflecting the fact that the uncovered
1597 -- else case is an unblocked exit.
1599 Unblocked_Exit_Count
:= 1;
1600 Analyze_Cond_Then
(N
);
1602 -- Now to analyze the elsif parts if any are present
1604 if Present
(Elsif_Parts
(N
)) then
1605 E
:= First
(Elsif_Parts
(N
));
1606 while Present
(E
) loop
1607 Analyze_Cond_Then
(E
);
1612 if Present
(Else_Statements
(N
)) then
1613 Analyze_Statements
(Else_Statements
(N
));
1616 -- If all our exits were blocked by unconditional transfers of control,
1617 -- then the entire IF statement acts as an unconditional transfer of
1618 -- control, so treat it like one, and check unreachable code.
1620 if Unblocked_Exit_Count
= 0 then
1621 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1622 Check_Unreachable_Code
(N
);
1624 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1628 Expander_Mode_Restore
;
1629 In_Deleted_Code
:= Save_In_Deleted_Code
;
1632 if not Expander_Active
1633 and then Compile_Time_Known_Value
(Condition
(N
))
1634 and then Serious_Errors_Detected
= 0
1636 if Is_True
(Expr_Value
(Condition
(N
))) then
1637 Remove_Warning_Messages
(Else_Statements
(N
));
1639 if Present
(Elsif_Parts
(N
)) then
1640 E
:= First
(Elsif_Parts
(N
));
1641 while Present
(E
) loop
1642 Remove_Warning_Messages
(Then_Statements
(E
));
1648 Remove_Warning_Messages
(Then_Statements
(N
));
1652 -- Warn on redundant if statement that has no effect
1654 -- Note, we could also check empty ELSIF parts ???
1656 if Warn_On_Redundant_Constructs
1658 -- If statement must be from source
1660 and then Comes_From_Source
(N
)
1662 -- Condition must not have obvious side effect
1664 and then Has_No_Obvious_Side_Effects
(Condition
(N
))
1666 -- No elsif parts of else part
1668 and then No
(Elsif_Parts
(N
))
1669 and then No
(Else_Statements
(N
))
1671 -- Then must be a single null statement
1673 and then List_Length
(Then_Statements
(N
)) = 1
1675 -- Go to original node, since we may have rewritten something as
1676 -- a null statement (e.g. a case we could figure the outcome of).
1679 T
: constant Node_Id
:= First
(Then_Statements
(N
));
1680 S
: constant Node_Id
:= Original_Node
(T
);
1683 if Comes_From_Source
(S
) and then Nkind
(S
) = N_Null_Statement
then
1684 Error_Msg_N
("if statement has no effect?r?", N
);
1688 end Analyze_If_Statement
;
1690 ----------------------------------------
1691 -- Analyze_Implicit_Label_Declaration --
1692 ----------------------------------------
1694 -- An implicit label declaration is generated in the innermost enclosing
1695 -- declarative part. This is done for labels, and block and loop names.
1697 -- Note: any changes in this routine may need to be reflected in
1698 -- Analyze_Label_Entity.
1700 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
1701 Id
: constant Node_Id
:= Defining_Identifier
(N
);
1704 Set_Ekind
(Id
, E_Label
);
1705 Set_Etype
(Id
, Standard_Void_Type
);
1706 Set_Enclosing_Scope
(Id
, Current_Scope
);
1707 end Analyze_Implicit_Label_Declaration
;
1709 ------------------------------
1710 -- Analyze_Iteration_Scheme --
1711 ------------------------------
1713 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
1715 Iter_Spec
: Node_Id
;
1716 Loop_Spec
: Node_Id
;
1719 -- For an infinite loop, there is no iteration scheme
1725 Cond
:= Condition
(N
);
1726 Iter_Spec
:= Iterator_Specification
(N
);
1727 Loop_Spec
:= Loop_Parameter_Specification
(N
);
1729 if Present
(Cond
) then
1730 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1731 Check_Unset_Reference
(Cond
);
1732 Set_Current_Value_Condition
(N
);
1734 elsif Present
(Iter_Spec
) then
1735 Analyze_Iterator_Specification
(Iter_Spec
);
1738 Analyze_Loop_Parameter_Specification
(Loop_Spec
);
1740 end Analyze_Iteration_Scheme
;
1742 ------------------------------------
1743 -- Analyze_Iterator_Specification --
1744 ------------------------------------
1746 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
1747 Loc
: constant Source_Ptr
:= Sloc
(N
);
1748 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
1749 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
1750 Iter_Name
: constant Node_Id
:= Name
(N
);
1756 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
);
1757 -- For an iteration over a container, if the loop carries the Reverse
1758 -- indicator, verify that the container type has an Iterate aspect that
1759 -- implements the reversible iterator interface.
1761 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
;
1762 -- For containers with Iterator and related aspects, the cursor is
1763 -- obtained by locating an entity with the proper name in the scope
1766 -----------------------------
1767 -- Check_Reverse_Iteration --
1768 -----------------------------
1770 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
) is
1772 if Reverse_Present
(N
)
1773 and then not Is_Array_Type
(Typ
)
1774 and then not Is_Reversible_Iterator
(Typ
)
1777 ("container type does not support reverse iteration", N
, Typ
);
1779 end Check_Reverse_Iteration
;
1781 ---------------------
1782 -- Get_Cursor_Type --
1783 ---------------------
1785 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
is
1789 Ent
:= First_Entity
(Scope
(Typ
));
1790 while Present
(Ent
) loop
1791 exit when Chars
(Ent
) = Name_Cursor
;
1799 -- The cursor is the target of generated assignments in the
1800 -- loop, and cannot have a limited type.
1802 if Is_Limited_Type
(Etype
(Ent
)) then
1803 Error_Msg_N
("cursor type cannot be limited", N
);
1807 end Get_Cursor_Type
;
1809 -- Start of processing for Analyze_iterator_Specification
1812 Enter_Name
(Def_Id
);
1814 -- AI12-0151 specifies that when the subtype indication is present, it
1815 -- must statically match the type of the array or container element.
1816 -- To simplify this check, we introduce a subtype declaration with the
1817 -- given subtype indication when it carries a constraint, and rewrite
1818 -- the original as a reference to the created subtype entity.
1820 if Present
(Subt
) then
1821 if Nkind
(Subt
) = N_Subtype_Indication
then
1823 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
1824 Decl
: constant Node_Id
:=
1825 Make_Subtype_Declaration
(Loc
,
1826 Defining_Identifier
=> S
,
1827 Subtype_Indication
=> New_Copy_Tree
(Subt
));
1829 Insert_Before
(Parent
(Parent
(N
)), Decl
);
1831 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
1837 -- Save entity of subtype indication for subsequent check
1839 Bas
:= Entity
(Subt
);
1842 Preanalyze_Range
(Iter_Name
);
1844 -- Set the kind of the loop variable, which is not visible within
1845 -- the iterator name.
1847 Set_Ekind
(Def_Id
, E_Variable
);
1849 -- Provide a link between the iterator variable and the container, for
1850 -- subsequent use in cross-reference and modification information.
1852 if Of_Present
(N
) then
1853 Set_Related_Expression
(Def_Id
, Iter_Name
);
1855 -- For a container, the iterator is specified through the aspect
1857 if not Is_Array_Type
(Etype
(Iter_Name
)) then
1859 Iterator
: constant Entity_Id
:=
1860 Find_Value_Of_Aspect
1861 (Etype
(Iter_Name
), Aspect_Default_Iterator
);
1867 if No
(Iterator
) then
1868 null; -- error reported below.
1870 elsif not Is_Overloaded
(Iterator
) then
1871 Check_Reverse_Iteration
(Etype
(Iterator
));
1873 -- If Iterator is overloaded, use reversible iterator if
1874 -- one is available.
1876 elsif Is_Overloaded
(Iterator
) then
1877 Get_First_Interp
(Iterator
, I
, It
);
1878 while Present
(It
.Nam
) loop
1879 if Ekind
(It
.Nam
) = E_Function
1880 and then Is_Reversible_Iterator
(Etype
(It
.Nam
))
1882 Set_Etype
(Iterator
, It
.Typ
);
1883 Set_Entity
(Iterator
, It
.Nam
);
1887 Get_Next_Interp
(I
, It
);
1890 Check_Reverse_Iteration
(Etype
(Iterator
));
1896 -- If the domain of iteration is an expression, create a declaration for
1897 -- it, so that finalization actions are introduced outside of the loop.
1898 -- The declaration must be a renaming because the body of the loop may
1899 -- assign to elements.
1901 if not Is_Entity_Name
(Iter_Name
)
1903 -- When the context is a quantified expression, the renaming
1904 -- declaration is delayed until the expansion phase if we are
1907 and then (Nkind
(Parent
(N
)) /= N_Quantified_Expression
1908 or else Operating_Mode
= Check_Semantics
)
1910 -- Do not perform this expansion in SPARK mode, since the formal
1911 -- verification directly deals with the source form of the iterator.
1912 -- Ditto for ASIS, where the temporary may hide the transformation
1913 -- of a selected component into a prefixed function call.
1915 and then not GNATprove_Mode
1916 and then not ASIS_Mode
1919 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
1925 -- If the domain of iteration is an array component that depends
1926 -- on a discriminant, create actual subtype for it. Pre-analysis
1927 -- does not generate the actual subtype of a selected component.
1929 if Nkind
(Iter_Name
) = N_Selected_Component
1930 and then Is_Array_Type
(Etype
(Iter_Name
))
1933 Build_Actual_Subtype_Of_Component
1934 (Etype
(Selector_Name
(Iter_Name
)), Iter_Name
);
1935 Insert_Action
(N
, Act_S
);
1937 if Present
(Act_S
) then
1938 Typ
:= Defining_Identifier
(Act_S
);
1940 Typ
:= Etype
(Iter_Name
);
1944 Typ
:= Etype
(Iter_Name
);
1946 -- Verify that the expression produces an iterator
1948 if not Of_Present
(N
) and then not Is_Iterator
(Typ
)
1949 and then not Is_Array_Type
(Typ
)
1950 and then No
(Find_Aspect
(Typ
, Aspect_Iterable
))
1953 ("expect object that implements iterator interface",
1958 -- Protect against malformed iterator
1960 if Typ
= Any_Type
then
1961 Error_Msg_N
("invalid expression in loop iterator", Iter_Name
);
1965 if not Of_Present
(N
) then
1966 Check_Reverse_Iteration
(Typ
);
1969 -- The name in the renaming declaration may be a function call.
1970 -- Indicate that it does not come from source, to suppress
1971 -- spurious warnings on renamings of parameterless functions,
1972 -- a common enough idiom in user-defined iterators.
1975 Make_Object_Renaming_Declaration
(Loc
,
1976 Defining_Identifier
=> Id
,
1977 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
1979 New_Copy_Tree
(Iter_Name
, New_Sloc
=> Loc
));
1981 -- Create a transient scope to ensure that all the temporaries
1982 -- generated by Remove_Side_Effects as part of processing this
1983 -- renaming declaration (if any) are attached by Insert_Actions
1984 -- to it. It has no effect on the generated code if no actions
1985 -- are added to it (see Wrap_Transient_Declaration).
1987 if Expander_Active
then
1988 Establish_Transient_Scope
(Name
(Decl
), Sec_Stack
=> True);
1991 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
1992 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
1993 Set_Etype
(Id
, Typ
);
1994 Set_Etype
(Name
(N
), Typ
);
1997 -- Container is an entity or an array with uncontrolled components, or
1998 -- else it is a container iterator given by a function call, typically
1999 -- called Iterate in the case of predefined containers, even though
2000 -- Iterate is not a reserved name. What matters is that the return type
2001 -- of the function is an iterator type.
2003 elsif Is_Entity_Name
(Iter_Name
) then
2004 Analyze
(Iter_Name
);
2006 if Nkind
(Iter_Name
) = N_Function_Call
then
2008 C
: constant Node_Id
:= Name
(Iter_Name
);
2013 if not Is_Overloaded
(Iter_Name
) then
2014 Resolve
(Iter_Name
, Etype
(C
));
2017 Get_First_Interp
(C
, I
, It
);
2018 while It
.Typ
/= Empty
loop
2019 if Reverse_Present
(N
) then
2020 if Is_Reversible_Iterator
(It
.Typ
) then
2021 Resolve
(Iter_Name
, It
.Typ
);
2025 elsif Is_Iterator
(It
.Typ
) then
2026 Resolve
(Iter_Name
, It
.Typ
);
2030 Get_Next_Interp
(I
, It
);
2035 -- Domain of iteration is not overloaded
2038 Resolve
(Iter_Name
, Etype
(Iter_Name
));
2041 if not Of_Present
(N
) then
2042 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2046 -- Get base type of container, for proper retrieval of Cursor type
2047 -- and primitive operations.
2049 Typ
:= Base_Type
(Etype
(Iter_Name
));
2051 if Is_Array_Type
(Typ
) then
2052 if Of_Present
(N
) then
2053 Set_Etype
(Def_Id
, Component_Type
(Typ
));
2055 -- The loop variable is aliased if the array components are
2058 Set_Is_Aliased
(Def_Id
, Has_Aliased_Components
(Typ
));
2060 -- AI12-0151 stipulates that the container cannot be a component
2061 -- that depends on a discriminant if the enclosing object is
2062 -- mutable, to prevent a modification of the container in the
2063 -- course of an iteration.
2065 -- Should comment on need to go to Original_Node ???
2067 if Nkind
(Original_Node
(Iter_Name
)) = N_Selected_Component
2068 and then Is_Dependent_Component_Of_Mutable_Object
2069 (Original_Node
(Iter_Name
))
2072 ("container cannot be a discriminant-dependent "
2073 & "component of a mutable object", N
);
2078 (Base_Type
(Bas
) /= Base_Type
(Component_Type
(Typ
))
2080 not Subtypes_Statically_Match
(Bas
, Component_Type
(Typ
)))
2083 ("subtype indication does not match component type", Subt
);
2086 -- Here we have a missing Range attribute
2090 ("missing Range attribute in iteration over an array", N
);
2092 -- In Ada 2012 mode, this may be an attempt at an iterator
2094 if Ada_Version
>= Ada_2012
then
2096 ("\if& is meant to designate an element of the array, use OF",
2100 -- Prevent cascaded errors
2102 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2103 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2106 -- Check for type error in iterator
2108 elsif Typ
= Any_Type
then
2111 -- Iteration over a container
2114 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2115 Error_Msg_Ada_2012_Feature
("container iterator", Sloc
(N
));
2119 if Of_Present
(N
) then
2120 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2122 Elt
: constant Entity_Id
:=
2123 Get_Iterable_Type_Primitive
(Typ
, Name_Element
);
2127 ("missing Element primitive for iteration", N
);
2129 Set_Etype
(Def_Id
, Etype
(Elt
));
2133 -- For a predefined container, The type of the loop variable is
2134 -- the Iterator_Element aspect of the container type.
2138 Element
: constant Entity_Id
:=
2139 Find_Value_Of_Aspect
(Typ
, Aspect_Iterator_Element
);
2140 Iterator
: constant Entity_Id
:=
2141 Find_Value_Of_Aspect
(Typ
, Aspect_Default_Iterator
);
2142 Cursor_Type
: Entity_Id
;
2145 if No
(Element
) then
2146 Error_Msg_NE
("cannot iterate over&", N
, Typ
);
2150 Set_Etype
(Def_Id
, Entity
(Element
));
2151 Cursor_Type
:= Get_Cursor_Type
(Typ
);
2152 pragma Assert
(Present
(Cursor_Type
));
2154 -- If subtype indication was given, verify that it covers
2155 -- the element type of the container.
2158 and then (not Covers
(Bas
, Etype
(Def_Id
))
2159 or else not Subtypes_Statically_Match
2160 (Bas
, Etype
(Def_Id
)))
2163 ("subtype indication does not match element type",
2167 -- If the container has a variable indexing aspect, the
2168 -- element is a variable and is modifiable in the loop.
2170 if Has_Aspect
(Typ
, Aspect_Variable_Indexing
) then
2171 Set_Ekind
(Def_Id
, E_Variable
);
2174 -- If the container is a constant, iterating over it
2175 -- requires a Constant_Indexing operation.
2177 if not Is_Variable
(Iter_Name
)
2178 and then not Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
2180 Error_Msg_N
("iteration over constant container "
2181 & "require constant_indexing aspect", N
);
2183 -- The Iterate function may have an in_out parameter,
2184 -- and a constant container is thus illegal.
2186 elsif Present
(Iterator
)
2187 and then Ekind
(Entity
(Iterator
)) = E_Function
2188 and then Ekind
(First_Formal
(Entity
(Iterator
))) /=
2190 and then not Is_Variable
(Iter_Name
)
2193 ("variable container expected", N
);
2196 if Nkind
(Original_Node
(Iter_Name
))
2197 = N_Selected_Component
2199 Is_Dependent_Component_Of_Mutable_Object
2200 (Original_Node
(Iter_Name
))
2203 ("container cannot be a discriminant-dependent "
2204 & "component of a mutable object", N
);
2210 -- IN iterator, domain is a range, or a call to Iterate function
2213 -- For an iteration of the form IN, the name must denote an
2214 -- iterator, typically the result of a call to Iterate. Give a
2215 -- useful error message when the name is a container by itself.
2217 -- The type may be a formal container type, which has to have
2218 -- an Iterable aspect detailing the required primitives.
2220 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2221 and then not Is_Iterator
(Typ
)
2223 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2226 elsif not Has_Aspect
(Typ
, Aspect_Iterator_Element
) then
2228 ("cannot iterate over&", Name
(N
), Typ
);
2231 ("name must be an iterator, not a container", Name
(N
));
2234 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2238 ("\to iterate directly over the elements of a container, "
2239 & "write `of &`", Name
(N
), Original_Node
(Name
(N
)));
2241 -- No point in continuing analysis of iterator spec
2247 -- If the name is a call (typically prefixed) to some Iterate
2248 -- function, it has been rewritten as an object declaration.
2249 -- If that object is a selected component, verify that it is not
2250 -- a component of an unconstrained mutable object.
2252 if Nkind
(Iter_Name
) = N_Identifier
then
2254 Orig_Node
: constant Node_Id
:= Original_Node
(Iter_Name
);
2255 Iter_Kind
: constant Node_Kind
:= Nkind
(Orig_Node
);
2259 if Iter_Kind
= N_Selected_Component
then
2260 Obj
:= Prefix
(Orig_Node
);
2262 elsif Iter_Kind
= N_Function_Call
then
2263 Obj
:= First_Actual
(Orig_Node
);
2265 -- If neither, the name comes from source
2271 if Nkind
(Obj
) = N_Selected_Component
2272 and then Is_Dependent_Component_Of_Mutable_Object
(Obj
)
2275 ("container cannot be a discriminant-dependent "
2276 & "component of a mutable object", N
);
2281 -- The result type of Iterate function is the classwide type of
2282 -- the interface parent. We need the specific Cursor type defined
2283 -- in the container package. We obtain it by name for a predefined
2284 -- container, or through the Iterable aspect for a formal one.
2286 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2289 (Parent
(Find_Value_Of_Aspect
(Typ
, Aspect_Iterable
)),
2291 Ent
:= Etype
(Def_Id
);
2294 Set_Etype
(Def_Id
, Get_Cursor_Type
(Typ
));
2300 -- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)).
2301 -- This check is relevant only when SPARK_Mode is on as it is not a
2302 -- standard Ada legality check.
2304 -- Not clear whether this applies to element iterators, where the
2305 -- cursor is not an explicit entity ???
2308 and then not Of_Present
(N
)
2309 and then Is_Effectively_Volatile
(Ent
)
2311 Error_Msg_N
("loop parameter cannot be volatile", Ent
);
2313 end Analyze_Iterator_Specification
;
2319 -- Note: the semantic work required for analyzing labels (setting them as
2320 -- reachable) was done in a prepass through the statements in the block,
2321 -- so that forward gotos would be properly handled. See Analyze_Statements
2322 -- for further details. The only processing required here is to deal with
2323 -- optimizations that depend on an assumption of sequential control flow,
2324 -- since of course the occurrence of a label breaks this assumption.
2326 procedure Analyze_Label
(N
: Node_Id
) is
2327 pragma Warnings
(Off
, N
);
2329 Kill_Current_Values
;
2332 --------------------------
2333 -- Analyze_Label_Entity --
2334 --------------------------
2336 procedure Analyze_Label_Entity
(E
: Entity_Id
) is
2338 Set_Ekind
(E
, E_Label
);
2339 Set_Etype
(E
, Standard_Void_Type
);
2340 Set_Enclosing_Scope
(E
, Current_Scope
);
2341 Set_Reachable
(E
, True);
2342 end Analyze_Label_Entity
;
2344 ------------------------------------------
2345 -- Analyze_Loop_Parameter_Specification --
2346 ------------------------------------------
2348 procedure Analyze_Loop_Parameter_Specification
(N
: Node_Id
) is
2349 Loop_Nod
: constant Node_Id
:= Parent
(Parent
(N
));
2351 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
2352 -- If the bounds are given by a 'Range reference on a function call
2353 -- that returns a controlled array, introduce an explicit declaration
2354 -- to capture the bounds, so that the function result can be finalized
2355 -- in timely fashion.
2357 procedure Check_Predicate_Use
(T
: Entity_Id
);
2358 -- Diagnose Attempt to iterate through non-static predicate. Note that
2359 -- a type with inherited predicates may have both static and dynamic
2360 -- forms. In this case it is not sufficent to check the static predicate
2361 -- function only, look for a dynamic predicate aspect as well.
2363 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean;
2364 -- N is the node for an arbitrary construct. This function searches the
2365 -- construct N to see if any expressions within it contain function
2366 -- calls that use the secondary stack, returning True if any such call
2367 -- is found, and False otherwise.
2369 procedure Process_Bounds
(R
: Node_Id
);
2370 -- If the iteration is given by a range, create temporaries and
2371 -- assignment statements block to capture the bounds and perform
2372 -- required finalization actions in case a bound includes a function
2373 -- call that uses the temporary stack. We first pre-analyze a copy of
2374 -- the range in order to determine the expected type, and analyze and
2375 -- resolve the original bounds.
2377 --------------------------------------
2378 -- Check_Controlled_Array_Attribute --
2379 --------------------------------------
2381 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
2383 if Nkind
(DS
) = N_Attribute_Reference
2384 and then Is_Entity_Name
(Prefix
(DS
))
2385 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
2386 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
2388 Is_Controlled
(Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
2389 and then Expander_Active
2392 Loc
: constant Source_Ptr
:= Sloc
(N
);
2393 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
2394 Indx
: constant Entity_Id
:=
2395 Base_Type
(Etype
(First_Index
(Arr
)));
2396 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
2401 Make_Subtype_Declaration
(Loc
,
2402 Defining_Identifier
=> Subt
,
2403 Subtype_Indication
=>
2404 Make_Subtype_Indication
(Loc
,
2405 Subtype_Mark
=> New_Occurrence_Of
(Indx
, Loc
),
2407 Make_Range_Constraint
(Loc
, Relocate_Node
(DS
))));
2408 Insert_Before
(Loop_Nod
, Decl
);
2412 Make_Attribute_Reference
(Loc
,
2413 Prefix
=> New_Occurrence_Of
(Subt
, Loc
),
2414 Attribute_Name
=> Attribute_Name
(DS
)));
2419 end Check_Controlled_Array_Attribute
;
2421 -------------------------
2422 -- Check_Predicate_Use --
2423 -------------------------
2425 procedure Check_Predicate_Use
(T
: Entity_Id
) is
2427 -- A predicated subtype is illegal in loops and related constructs
2428 -- if the predicate is not static, or if it is a non-static subtype
2429 -- of a statically predicated subtype.
2431 if Is_Discrete_Type
(T
)
2432 and then Has_Predicates
(T
)
2433 and then (not Has_Static_Predicate
(T
)
2434 or else not Is_Static_Subtype
(T
)
2435 or else Has_Dynamic_Predicate_Aspect
(T
))
2437 -- Seems a confusing message for the case of a static predicate
2438 -- with a non-static subtype???
2440 Bad_Predicated_Subtype_Use
2441 ("cannot use subtype& with non-static predicate for loop "
2442 & "iteration", Discrete_Subtype_Definition
(N
),
2443 T
, Suggest_Static
=> True);
2445 elsif Inside_A_Generic
and then Is_Generic_Formal
(T
) then
2446 Set_No_Dynamic_Predicate_On_Actual
(T
);
2448 end Check_Predicate_Use
;
2450 ------------------------------------
2451 -- Has_Call_Using_Secondary_Stack --
2452 ------------------------------------
2454 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean is
2456 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
2457 -- Check if N is a function call which uses the secondary stack
2463 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
2466 Return_Typ
: Entity_Id
;
2469 if Nkind
(N
) = N_Function_Call
then
2472 -- Call using access to subprogram with explicit dereference
2474 if Nkind
(Nam
) = N_Explicit_Dereference
then
2475 Subp
:= Etype
(Nam
);
2477 -- Call using a selected component notation or Ada 2005 object
2478 -- operation notation
2480 elsif Nkind
(Nam
) = N_Selected_Component
then
2481 Subp
:= Entity
(Selector_Name
(Nam
));
2486 Subp
:= Entity
(Nam
);
2489 Return_Typ
:= Etype
(Subp
);
2491 if Is_Composite_Type
(Return_Typ
)
2492 and then not Is_Constrained
(Return_Typ
)
2496 elsif Sec_Stack_Needed_For_Return
(Subp
) then
2501 -- Continue traversing the tree
2506 function Check_Calls
is new Traverse_Func
(Check_Call
);
2508 -- Start of processing for Has_Call_Using_Secondary_Stack
2511 return Check_Calls
(N
) = Abandon
;
2512 end Has_Call_Using_Secondary_Stack
;
2514 --------------------
2515 -- Process_Bounds --
2516 --------------------
2518 procedure Process_Bounds
(R
: Node_Id
) is
2519 Loc
: constant Source_Ptr
:= Sloc
(N
);
2522 (Original_Bound
: Node_Id
;
2523 Analyzed_Bound
: Node_Id
;
2524 Typ
: Entity_Id
) return Node_Id
;
2525 -- Capture value of bound and return captured value
2532 (Original_Bound
: Node_Id
;
2533 Analyzed_Bound
: Node_Id
;
2534 Typ
: Entity_Id
) return Node_Id
2541 -- If the bound is a constant or an object, no need for a separate
2542 -- declaration. If the bound is the result of previous expansion
2543 -- it is already analyzed and should not be modified. Note that
2544 -- the Bound will be resolved later, if needed, as part of the
2545 -- call to Make_Index (literal bounds may need to be resolved to
2548 if Analyzed
(Original_Bound
) then
2549 return Original_Bound
;
2551 elsif Nkind_In
(Analyzed_Bound
, N_Integer_Literal
,
2552 N_Character_Literal
)
2553 or else Is_Entity_Name
(Analyzed_Bound
)
2555 Analyze_And_Resolve
(Original_Bound
, Typ
);
2556 return Original_Bound
;
2559 -- Normally, the best approach is simply to generate a constant
2560 -- declaration that captures the bound. However, there is a nasty
2561 -- case where this is wrong. If the bound is complex, and has a
2562 -- possible use of the secondary stack, we need to generate a
2563 -- separate assignment statement to ensure the creation of a block
2564 -- which will release the secondary stack.
2566 -- We prefer the constant declaration, since it leaves us with a
2567 -- proper trace of the value, useful in optimizations that get rid
2568 -- of junk range checks.
2570 if not Has_Call_Using_Secondary_Stack
(Analyzed_Bound
) then
2571 Analyze_And_Resolve
(Original_Bound
, Typ
);
2573 -- Ensure that the bound is valid. This check should not be
2574 -- generated when the range belongs to a quantified expression
2575 -- as the construct is still not expanded into its final form.
2577 if Nkind
(Parent
(R
)) /= N_Loop_Parameter_Specification
2578 or else Nkind
(Parent
(Parent
(R
))) /= N_Quantified_Expression
2580 Ensure_Valid
(Original_Bound
);
2583 Force_Evaluation
(Original_Bound
);
2584 return Original_Bound
;
2587 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
2589 -- Here we make a declaration with a separate assignment
2590 -- statement, and insert before loop header.
2593 Make_Object_Declaration
(Loc
,
2594 Defining_Identifier
=> Id
,
2595 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
2598 Make_Assignment_Statement
(Loc
,
2599 Name
=> New_Occurrence_Of
(Id
, Loc
),
2600 Expression
=> Relocate_Node
(Original_Bound
));
2602 Insert_Actions
(Loop_Nod
, New_List
(Decl
, Assign
));
2604 -- Now that this temporary variable is initialized we decorate it
2605 -- as safe-to-reevaluate to inform to the backend that no further
2606 -- asignment will be issued and hence it can be handled as side
2607 -- effect free. Note that this decoration must be done when the
2608 -- assignment has been analyzed because otherwise it will be
2609 -- rejected (see Analyze_Assignment).
2611 Set_Is_Safe_To_Reevaluate
(Id
);
2613 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
2615 if Nkind
(Assign
) = N_Assignment_Statement
then
2616 return Expression
(Assign
);
2618 return Original_Bound
;
2622 Hi
: constant Node_Id
:= High_Bound
(R
);
2623 Lo
: constant Node_Id
:= Low_Bound
(R
);
2624 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
2629 -- Start of processing for Process_Bounds
2632 Set_Parent
(R_Copy
, Parent
(R
));
2633 Preanalyze_Range
(R_Copy
);
2634 Typ
:= Etype
(R_Copy
);
2636 -- If the type of the discrete range is Universal_Integer, then the
2637 -- bound's type must be resolved to Integer, and any object used to
2638 -- hold the bound must also have type Integer, unless the literal
2639 -- bounds are constant-folded expressions with a user-defined type.
2641 if Typ
= Universal_Integer
then
2642 if Nkind
(Lo
) = N_Integer_Literal
2643 and then Present
(Etype
(Lo
))
2644 and then Scope
(Etype
(Lo
)) /= Standard_Standard
2648 elsif Nkind
(Hi
) = N_Integer_Literal
2649 and then Present
(Etype
(Hi
))
2650 and then Scope
(Etype
(Hi
)) /= Standard_Standard
2655 Typ
:= Standard_Integer
;
2661 New_Lo
:= One_Bound
(Lo
, Low_Bound
(R_Copy
), Typ
);
2662 New_Hi
:= One_Bound
(Hi
, High_Bound
(R_Copy
), Typ
);
2664 -- Propagate staticness to loop range itself, in case the
2665 -- corresponding subtype is static.
2667 if New_Lo
/= Lo
and then Is_OK_Static_Expression
(New_Lo
) then
2668 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo
));
2671 if New_Hi
/= Hi
and then Is_OK_Static_Expression
(New_Hi
) then
2672 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi
));
2678 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(N
);
2679 Id
: constant Entity_Id
:= Defining_Identifier
(N
);
2683 -- Start of processing for Analyze_Loop_Parameter_Specification
2688 -- We always consider the loop variable to be referenced, since the loop
2689 -- may be used just for counting purposes.
2691 Generate_Reference
(Id
, N
, ' ');
2693 -- Check for the case of loop variable hiding a local variable (used
2694 -- later on to give a nice warning if the hidden variable is never
2698 H
: constant Entity_Id
:= Homonym
(Id
);
2701 and then Ekind
(H
) = E_Variable
2702 and then Is_Discrete_Type
(Etype
(H
))
2703 and then Enclosing_Dynamic_Scope
(H
) = Enclosing_Dynamic_Scope
(Id
)
2705 Set_Hiding_Loop_Variable
(H
, Id
);
2709 -- Loop parameter specification must include subtype mark in SPARK
2711 if Nkind
(DS
) = N_Range
then
2712 Check_SPARK_05_Restriction
2713 ("loop parameter specification must include subtype mark", N
);
2716 -- Analyze the subtype definition and create temporaries for the bounds.
2717 -- Do not evaluate the range when preanalyzing a quantified expression
2718 -- because bounds expressed as function calls with side effects will be
2719 -- incorrectly replicated.
2721 if Nkind
(DS
) = N_Range
2722 and then Expander_Active
2723 and then Nkind
(Parent
(N
)) /= N_Quantified_Expression
2725 Process_Bounds
(DS
);
2727 -- Either the expander not active or the range of iteration is a subtype
2728 -- indication, an entity, or a function call that yields an aggregate or
2732 DS_Copy
:= New_Copy_Tree
(DS
);
2733 Set_Parent
(DS_Copy
, Parent
(DS
));
2734 Preanalyze_Range
(DS_Copy
);
2736 -- Ada 2012: If the domain of iteration is:
2738 -- a) a function call,
2739 -- b) an identifier that is not a type,
2740 -- c) an attribute reference 'Old (within a postcondition)
2741 -- d) an unchecked conversion
2743 -- then it is an iteration over a container. It was classified as
2744 -- a loop specification by the parser, and must be rewritten now
2745 -- to activate container iteration. The last case will occur within
2746 -- an expanded inlined call, where the expansion wraps an actual in
2747 -- an unchecked conversion when needed. The expression of the
2748 -- conversion is always an object.
2750 if Nkind
(DS_Copy
) = N_Function_Call
2751 or else (Is_Entity_Name
(DS_Copy
)
2752 and then not Is_Type
(Entity
(DS_Copy
)))
2753 or else (Nkind
(DS_Copy
) = N_Attribute_Reference
2754 and then Nam_In
(Attribute_Name
(DS_Copy
),
2755 Name_Old
, Name_Loop_Entry
))
2756 or else Nkind
(DS_Copy
) = N_Unchecked_Type_Conversion
2757 or else Has_Aspect
(Etype
(DS_Copy
), Aspect_Iterable
)
2759 -- This is an iterator specification. Rewrite it as such and
2760 -- analyze it to capture function calls that may require
2761 -- finalization actions.
2764 I_Spec
: constant Node_Id
:=
2765 Make_Iterator_Specification
(Sloc
(N
),
2766 Defining_Identifier
=> Relocate_Node
(Id
),
2768 Subtype_Indication
=> Empty
,
2769 Reverse_Present
=> Reverse_Present
(N
));
2770 Scheme
: constant Node_Id
:= Parent
(N
);
2773 Set_Iterator_Specification
(Scheme
, I_Spec
);
2774 Set_Loop_Parameter_Specification
(Scheme
, Empty
);
2775 Analyze_Iterator_Specification
(I_Spec
);
2777 -- In a generic context, analyze the original domain of
2778 -- iteration, for name capture.
2780 if not Expander_Active
then
2784 -- Set kind of loop parameter, which may be used in the
2785 -- subsequent analysis of the condition in a quantified
2788 Set_Ekind
(Id
, E_Loop_Parameter
);
2792 -- Domain of iteration is not a function call, and is side-effect
2796 -- A quantified expression that appears in a pre/post condition
2797 -- is pre-analyzed several times. If the range is given by an
2798 -- attribute reference it is rewritten as a range, and this is
2799 -- done even with expansion disabled. If the type is already set
2800 -- do not reanalyze, because a range with static bounds may be
2801 -- typed Integer by default.
2803 if Nkind
(Parent
(N
)) = N_Quantified_Expression
2804 and then Present
(Etype
(DS
))
2817 -- Some additional checks if we are iterating through a type
2819 if Is_Entity_Name
(DS
)
2820 and then Present
(Entity
(DS
))
2821 and then Is_Type
(Entity
(DS
))
2823 -- The subtype indication may denote the completion of an incomplete
2824 -- type declaration.
2826 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
2827 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
2828 Set_Etype
(DS
, Entity
(DS
));
2831 Check_Predicate_Use
(Entity
(DS
));
2834 -- Error if not discrete type
2836 if not Is_Discrete_Type
(Etype
(DS
)) then
2837 Wrong_Type
(DS
, Any_Discrete
);
2838 Set_Etype
(DS
, Any_Type
);
2841 Check_Controlled_Array_Attribute
(DS
);
2843 if Nkind
(DS
) = N_Subtype_Indication
then
2844 Check_Predicate_Use
(Entity
(Subtype_Mark
(DS
)));
2847 Make_Index
(DS
, N
, In_Iter_Schm
=> True);
2848 Set_Ekind
(Id
, E_Loop_Parameter
);
2850 -- A quantified expression which appears in a pre- or post-condition may
2851 -- be analyzed multiple times. The analysis of the range creates several
2852 -- itypes which reside in different scopes depending on whether the pre-
2853 -- or post-condition has been expanded. Update the type of the loop
2854 -- variable to reflect the proper itype at each stage of analysis.
2857 or else Etype
(Id
) = Any_Type
2859 (Present
(Etype
(Id
))
2860 and then Is_Itype
(Etype
(Id
))
2861 and then Nkind
(Parent
(Loop_Nod
)) = N_Expression_With_Actions
2862 and then Nkind
(Original_Node
(Parent
(Loop_Nod
))) =
2863 N_Quantified_Expression
)
2865 Set_Etype
(Id
, Etype
(DS
));
2868 -- Treat a range as an implicit reference to the type, to inhibit
2869 -- spurious warnings.
2871 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
2872 Set_Is_Known_Valid
(Id
, True);
2874 -- The loop is not a declarative part, so the loop variable must be
2875 -- frozen explicitly. Do not freeze while preanalyzing a quantified
2876 -- expression because the freeze node will not be inserted into the
2877 -- tree due to flag Is_Spec_Expression being set.
2879 if Nkind
(Parent
(N
)) /= N_Quantified_Expression
then
2881 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
2883 if Is_Non_Empty_List
(Flist
) then
2884 Insert_Actions
(N
, Flist
);
2889 -- Case where we have a range or a subtype, get type bounds
2891 if Nkind_In
(DS
, N_Range
, N_Subtype_Indication
)
2892 and then not Error_Posted
(DS
)
2893 and then Etype
(DS
) /= Any_Type
2894 and then Is_Discrete_Type
(Etype
(DS
))
2901 if Nkind
(DS
) = N_Range
then
2902 L
:= Low_Bound
(DS
);
2903 H
:= High_Bound
(DS
);
2906 Type_Low_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
2908 Type_High_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
2911 -- Check for null or possibly null range and issue warning. We
2912 -- suppress such messages in generic templates and instances,
2913 -- because in practice they tend to be dubious in these cases. The
2914 -- check applies as well to rewritten array element loops where a
2915 -- null range may be detected statically.
2917 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> True) = GT
then
2919 -- Suppress the warning if inside a generic template or
2920 -- instance, since in practice they tend to be dubious in these
2921 -- cases since they can result from intended parameterization.
2923 if not Inside_A_Generic
and then not In_Instance
then
2925 -- Specialize msg if invalid values could make the loop
2926 -- non-null after all.
2928 if Compile_Time_Compare
2929 (L
, H
, Assume_Valid
=> False) = GT
2931 -- Since we know the range of the loop is null, set the
2932 -- appropriate flag to remove the loop entirely during
2935 Set_Is_Null_Loop
(Loop_Nod
);
2937 if Comes_From_Source
(N
) then
2939 ("??loop range is null, loop will not execute", DS
);
2942 -- Here is where the loop could execute because of
2943 -- invalid values, so issue appropriate message and in
2944 -- this case we do not set the Is_Null_Loop flag since
2945 -- the loop may execute.
2947 elsif Comes_From_Source
(N
) then
2949 ("??loop range may be null, loop may not execute",
2952 ("??can only execute if invalid values are present",
2957 -- In either case, suppress warnings in the body of the loop,
2958 -- since it is likely that these warnings will be inappropriate
2959 -- if the loop never actually executes, which is likely.
2961 Set_Suppress_Loop_Warnings
(Loop_Nod
);
2963 -- The other case for a warning is a reverse loop where the
2964 -- upper bound is the integer literal zero or one, and the
2965 -- lower bound may exceed this value.
2967 -- For example, we have
2969 -- for J in reverse N .. 1 loop
2971 -- In practice, this is very likely to be a case of reversing
2972 -- the bounds incorrectly in the range.
2974 elsif Reverse_Present
(N
)
2975 and then Nkind
(Original_Node
(H
)) = N_Integer_Literal
2977 (Intval
(Original_Node
(H
)) = Uint_0
2979 Intval
(Original_Node
(H
)) = Uint_1
)
2981 -- Lower bound may in fact be known and known not to exceed
2982 -- upper bound (e.g. reverse 0 .. 1) and that's OK.
2984 if Compile_Time_Known_Value
(L
)
2985 and then Expr_Value
(L
) <= Expr_Value
(H
)
2989 -- Otherwise warning is warranted
2992 Error_Msg_N
("??loop range may be null", DS
);
2993 Error_Msg_N
("\??bounds may be wrong way round", DS
);
2997 -- Check if either bound is known to be outside the range of the
2998 -- loop parameter type, this is e.g. the case of a loop from
2999 -- 20..X where the type is 1..19.
3001 -- Such a loop is dubious since either it raises CE or it executes
3002 -- zero times, and that cannot be useful!
3004 if Etype
(DS
) /= Any_Type
3005 and then not Error_Posted
(DS
)
3006 and then Nkind
(DS
) = N_Subtype_Indication
3007 and then Nkind
(Constraint
(DS
)) = N_Range_Constraint
3010 LLo
: constant Node_Id
:=
3011 Low_Bound
(Range_Expression
(Constraint
(DS
)));
3012 LHi
: constant Node_Id
:=
3013 High_Bound
(Range_Expression
(Constraint
(DS
)));
3015 Bad_Bound
: Node_Id
:= Empty
;
3016 -- Suspicious loop bound
3019 -- At this stage L, H are the bounds of the type, and LLo
3020 -- Lhi are the low bound and high bound of the loop.
3022 if Compile_Time_Compare
(LLo
, L
, Assume_Valid
=> True) = LT
3024 Compile_Time_Compare
(LLo
, H
, Assume_Valid
=> True) = GT
3029 if Compile_Time_Compare
(LHi
, L
, Assume_Valid
=> True) = LT
3031 Compile_Time_Compare
(LHi
, H
, Assume_Valid
=> True) = GT
3036 if Present
(Bad_Bound
) then
3038 ("suspicious loop bound out of range of "
3039 & "loop subtype??", Bad_Bound
);
3041 ("\loop executes zero times or raises "
3042 & "Constraint_Error??", Bad_Bound
);
3047 -- This declare block is about warnings, if we get an exception while
3048 -- testing for warnings, we simply abandon the attempt silently. This
3049 -- most likely occurs as the result of a previous error, but might
3050 -- just be an obscure case we have missed. In either case, not giving
3051 -- the warning is perfectly acceptable.
3054 when others => null;
3058 -- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)).
3059 -- This check is relevant only when SPARK_Mode is on as it is not a
3060 -- standard Ada legality check.
3062 if SPARK_Mode
= On
and then Is_Effectively_Volatile
(Id
) then
3063 Error_Msg_N
("loop parameter cannot be volatile", Id
);
3065 end Analyze_Loop_Parameter_Specification
;
3067 ----------------------------
3068 -- Analyze_Loop_Statement --
3069 ----------------------------
3071 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
3073 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean;
3074 -- Given a loop iteration scheme, determine whether it is an Ada 2012
3075 -- container iteration.
3077 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean;
3078 -- Determine whether loop statement N has been wrapped in a block to
3079 -- capture finalization actions that may be generated for container
3080 -- iterators. Prevents infinite recursion when block is analyzed.
3081 -- Routine is a noop if loop is single statement within source block.
3083 ---------------------------
3084 -- Is_Container_Iterator --
3085 ---------------------------
3087 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean is
3096 elsif Present
(Condition
(Iter
)) then
3099 -- for Def_Id in [reverse] Name loop
3100 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
3102 elsif Present
(Iterator_Specification
(Iter
)) then
3104 Nam
: constant Node_Id
:= Name
(Iterator_Specification
(Iter
));
3108 Nam_Copy
:= New_Copy_Tree
(Nam
);
3109 Set_Parent
(Nam_Copy
, Parent
(Nam
));
3110 Preanalyze_Range
(Nam_Copy
);
3112 -- The only two options here are iteration over a container or
3115 return not Is_Array_Type
(Etype
(Nam_Copy
));
3118 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
3122 LP
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3123 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(LP
);
3127 DS_Copy
:= New_Copy_Tree
(DS
);
3128 Set_Parent
(DS_Copy
, Parent
(DS
));
3129 Preanalyze_Range
(DS_Copy
);
3131 -- Check for a call to Iterate ()
3134 Nkind
(DS_Copy
) = N_Function_Call
3135 and then Needs_Finalization
(Etype
(DS_Copy
));
3138 end Is_Container_Iterator
;
3140 -------------------------
3141 -- Is_Wrapped_In_Block --
3142 -------------------------
3144 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean is
3150 -- Check if current scope is a block that is not a transient block.
3152 if Ekind
(Current_Scope
) /= E_Block
3153 or else No
(Block_Node
(Current_Scope
))
3159 Handled_Statement_Sequence
(Parent
(Block_Node
(Current_Scope
)));
3161 -- Skip leading pragmas that may be introduced for invariant and
3162 -- predicate checks.
3164 Stat
:= First
(Statements
(HSS
));
3165 while Present
(Stat
) and then Nkind
(Stat
) = N_Pragma
loop
3166 Stat
:= Next
(Stat
);
3169 return Stat
= N
and then No
(Next
(Stat
));
3171 end Is_Wrapped_In_Block
;
3173 -- Local declarations
3175 Id
: constant Node_Id
:= Identifier
(N
);
3176 Iter
: constant Node_Id
:= Iteration_Scheme
(N
);
3177 Loc
: constant Source_Ptr
:= Sloc
(N
);
3181 -- Start of processing for Analyze_Loop_Statement
3184 if Present
(Id
) then
3186 -- Make name visible, e.g. for use in exit statements. Loop labels
3187 -- are always considered to be referenced.
3192 -- Guard against serious error (typically, a scope mismatch when
3193 -- semantic analysis is requested) by creating loop entity to
3194 -- continue analysis.
3197 if Total_Errors_Detected
/= 0 then
3198 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3200 raise Program_Error
;
3203 -- Verify that the loop name is hot hidden by an unrelated
3204 -- declaration in an inner scope.
3206 elsif Ekind
(Ent
) /= E_Label
and then Ekind
(Ent
) /= E_Loop
then
3207 Error_Msg_Sloc
:= Sloc
(Ent
);
3208 Error_Msg_N
("implicit label declaration for & is hidden#", Id
);
3210 if Present
(Homonym
(Ent
))
3211 and then Ekind
(Homonym
(Ent
)) = E_Label
3213 Set_Entity
(Id
, Ent
);
3214 Set_Ekind
(Ent
, E_Loop
);
3218 Generate_Reference
(Ent
, N
, ' ');
3219 Generate_Definition
(Ent
);
3221 -- If we found a label, mark its type. If not, ignore it, since it
3222 -- means we have a conflicting declaration, which would already
3223 -- have been diagnosed at declaration time. Set Label_Construct
3224 -- of the implicit label declaration, which is not created by the
3225 -- parser for generic units.
3227 if Ekind
(Ent
) = E_Label
then
3228 Set_Ekind
(Ent
, E_Loop
);
3230 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
3231 Set_Label_Construct
(Parent
(Ent
), N
);
3236 -- Case of no identifier present. Create one and attach it to the
3237 -- loop statement for use as a scope and as a reference for later
3238 -- expansions. Indicate that the label does not come from source,
3239 -- and attach it to the loop statement so it is part of the tree,
3240 -- even without a full declaration.
3243 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3244 Set_Etype
(Ent
, Standard_Void_Type
);
3245 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Loc
));
3246 Set_Parent
(Ent
, N
);
3247 Set_Has_Created_Identifier
(N
);
3250 -- Iteration over a container in Ada 2012 involves the creation of a
3251 -- controlled iterator object. Wrap the loop in a block to ensure the
3252 -- timely finalization of the iterator and release of container locks.
3253 -- The same applies to the use of secondary stack when obtaining an
3256 if Ada_Version
>= Ada_2012
3257 and then Is_Container_Iterator
(Iter
)
3258 and then not Is_Wrapped_In_Block
(N
)
3261 Block_Nod
: Node_Id
;
3262 Block_Id
: Entity_Id
;
3266 Make_Block_Statement
(Loc
,
3267 Declarations
=> New_List
,
3268 Handled_Statement_Sequence
=>
3269 Make_Handled_Sequence_Of_Statements
(Loc
,
3270 Statements
=> New_List
(Relocate_Node
(N
))));
3272 Add_Block_Identifier
(Block_Nod
, Block_Id
);
3274 -- The expansion of iterator loops generates an iterator in order
3275 -- to traverse the elements of a container:
3277 -- Iter : <iterator type> := Iterate (Container)'reference;
3279 -- The iterator is controlled and returned on the secondary stack.
3280 -- The analysis of the call to Iterate establishes a transient
3281 -- scope to deal with the secondary stack management, but never
3282 -- really creates a physical block as this would kill the iterator
3283 -- too early (see Wrap_Transient_Declaration). To address this
3284 -- case, mark the generated block as needing secondary stack
3287 Set_Uses_Sec_Stack
(Block_Id
);
3289 Rewrite
(N
, Block_Nod
);
3295 -- Kill current values on entry to loop, since statements in the body of
3296 -- the loop may have been executed before the loop is entered. Similarly
3297 -- we kill values after the loop, since we do not know that the body of
3298 -- the loop was executed.
3300 Kill_Current_Values
;
3302 Analyze_Iteration_Scheme
(Iter
);
3304 -- Check for following case which merits a warning if the type E of is
3305 -- a multi-dimensional array (and no explicit subscript ranges present).
3311 and then Present
(Loop_Parameter_Specification
(Iter
))
3314 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3315 DSD
: constant Node_Id
:=
3316 Original_Node
(Discrete_Subtype_Definition
(LPS
));
3318 if Nkind
(DSD
) = N_Attribute_Reference
3319 and then Attribute_Name
(DSD
) = Name_Range
3320 and then No
(Expressions
(DSD
))
3323 Typ
: constant Entity_Id
:= Etype
(Prefix
(DSD
));
3325 if Is_Array_Type
(Typ
)
3326 and then Number_Dimensions
(Typ
) > 1
3327 and then Nkind
(Parent
(N
)) = N_Loop_Statement
3328 and then Present
(Iteration_Scheme
(Parent
(N
)))
3331 OIter
: constant Node_Id
:=
3332 Iteration_Scheme
(Parent
(N
));
3333 OLPS
: constant Node_Id
:=
3334 Loop_Parameter_Specification
(OIter
);
3335 ODSD
: constant Node_Id
:=
3336 Original_Node
(Discrete_Subtype_Definition
(OLPS
));
3338 if Nkind
(ODSD
) = N_Attribute_Reference
3339 and then Attribute_Name
(ODSD
) = Name_Range
3340 and then No
(Expressions
(ODSD
))
3341 and then Etype
(Prefix
(ODSD
)) = Typ
3343 Error_Msg_Sloc
:= Sloc
(ODSD
);
3345 ("inner range same as outer range#??", DSD
);
3354 -- Analyze the statements of the body except in the case of an Ada 2012
3355 -- iterator with the expander active. In this case the expander will do
3356 -- a rewrite of the loop into a while loop. We will then analyze the
3357 -- loop body when we analyze this while loop.
3359 -- We need to do this delay because if the container is for indefinite
3360 -- types the actual subtype of the components will only be determined
3361 -- when the cursor declaration is analyzed.
3363 -- If the expander is not active then we want to analyze the loop body
3364 -- now even in the Ada 2012 iterator case, since the rewriting will not
3365 -- be done. Insert the loop variable in the current scope, if not done
3366 -- when analysing the iteration scheme. Set its kind properly to detect
3367 -- improper uses in the loop body.
3369 -- In GNATprove mode, we do one of the above depending on the kind of
3370 -- loop. If it is an iterator over an array, then we do not analyze the
3371 -- loop now. We will analyze it after it has been rewritten by the
3372 -- special SPARK expansion which is activated in GNATprove mode. We need
3373 -- to do this so that other expansions that should occur in GNATprove
3374 -- mode take into account the specificities of the rewritten loop, in
3375 -- particular the introduction of a renaming (which needs to be
3378 -- In other cases in GNATprove mode then we want to analyze the loop
3379 -- body now, since no rewriting will occur.
3382 and then Present
(Iterator_Specification
(Iter
))
3385 and then Is_Iterator_Over_Array
(Iterator_Specification
(Iter
))
3389 elsif not Expander_Active
then
3391 I_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
3392 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3395 if Scope
(Id
) /= Current_Scope
then
3399 -- In an element iterator, The loop parameter is a variable if
3400 -- the domain of iteration (container or array) is a variable.
3402 if not Of_Present
(I_Spec
)
3403 or else not Is_Variable
(Name
(I_Spec
))
3405 Set_Ekind
(Id
, E_Loop_Parameter
);
3409 Analyze_Statements
(Statements
(N
));
3414 -- Pre-Ada2012 for-loops and while loops.
3416 Analyze_Statements
(Statements
(N
));
3419 -- When the iteration scheme of a loop contains attribute 'Loop_Entry,
3420 -- the loop is transformed into a conditional block. Retrieve the loop.
3424 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
3425 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
3428 -- Finish up processing for the loop. We kill all current values, since
3429 -- in general we don't know if the statements in the loop have been
3430 -- executed. We could do a bit better than this with a loop that we
3431 -- know will execute at least once, but it's not worth the trouble and
3432 -- the front end is not in the business of flow tracing.
3434 Process_End_Label
(Stmt
, 'e', Ent
);
3436 Kill_Current_Values
;
3438 -- Check for infinite loop. Skip check for generated code, since it
3439 -- justs waste time and makes debugging the routine called harder.
3441 -- Note that we have to wait till the body of the loop is fully analyzed
3442 -- before making this call, since Check_Infinite_Loop_Warning relies on
3443 -- being able to use semantic visibility information to find references.
3445 if Comes_From_Source
(Stmt
) then
3446 Check_Infinite_Loop_Warning
(Stmt
);
3449 -- Code after loop is unreachable if the loop has no WHILE or FOR and
3450 -- contains no EXIT statements within the body of the loop.
3452 if No
(Iter
) and then not Has_Exit
(Ent
) then
3453 Check_Unreachable_Code
(Stmt
);
3455 end Analyze_Loop_Statement
;
3457 ----------------------------
3458 -- Analyze_Null_Statement --
3459 ----------------------------
3461 -- Note: the semantics of the null statement is implemented by a single
3462 -- null statement, too bad everything isn't as simple as this.
3464 procedure Analyze_Null_Statement
(N
: Node_Id
) is
3465 pragma Warnings
(Off
, N
);
3468 end Analyze_Null_Statement
;
3470 ------------------------
3471 -- Analyze_Statements --
3472 ------------------------
3474 procedure Analyze_Statements
(L
: List_Id
) is
3479 -- The labels declared in the statement list are reachable from
3480 -- statements in the list. We do this as a prepass so that any goto
3481 -- statement will be properly flagged if its target is not reachable.
3482 -- This is not required, but is nice behavior.
3485 while Present
(S
) loop
3486 if Nkind
(S
) = N_Label
then
3487 Analyze
(Identifier
(S
));
3488 Lab
:= Entity
(Identifier
(S
));
3490 -- If we found a label mark it as reachable
3492 if Ekind
(Lab
) = E_Label
then
3493 Generate_Definition
(Lab
);
3494 Set_Reachable
(Lab
);
3496 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
3497 Set_Label_Construct
(Parent
(Lab
), S
);
3500 -- If we failed to find a label, it means the implicit declaration
3501 -- of the label was hidden. A for-loop parameter can do this to
3502 -- a label with the same name inside the loop, since the implicit
3503 -- label declaration is in the innermost enclosing body or block
3507 Error_Msg_Sloc
:= Sloc
(Lab
);
3509 ("implicit label declaration for & is hidden#",
3517 -- Perform semantic analysis on all statements
3519 Conditional_Statements_Begin
;
3522 while Present
(S
) loop
3525 -- Remove dimension in all statements
3527 Remove_Dimension_In_Statement
(S
);
3531 Conditional_Statements_End
;
3533 -- Make labels unreachable. Visibility is not sufficient, because labels
3534 -- in one if-branch for example are not reachable from the other branch,
3535 -- even though their declarations are in the enclosing declarative part.
3538 while Present
(S
) loop
3539 if Nkind
(S
) = N_Label
then
3540 Set_Reachable
(Entity
(Identifier
(S
)), False);
3545 end Analyze_Statements
;
3547 ----------------------------
3548 -- Check_Unreachable_Code --
3549 ----------------------------
3551 procedure Check_Unreachable_Code
(N
: Node_Id
) is
3552 Error_Node
: Node_Id
;
3556 if Is_List_Member
(N
) and then Comes_From_Source
(N
) then
3561 Nxt
:= Original_Node
(Next
(N
));
3563 -- Skip past pragmas
3565 while Nkind
(Nxt
) = N_Pragma
loop
3566 Nxt
:= Original_Node
(Next
(Nxt
));
3569 -- If a label follows us, then we never have dead code, since
3570 -- someone could branch to the label, so we just ignore it, unless
3571 -- we are in formal mode where goto statements are not allowed.
3573 if Nkind
(Nxt
) = N_Label
3574 and then not Restriction_Check_Required
(SPARK_05
)
3578 -- Otherwise see if we have a real statement following us
3581 and then Comes_From_Source
(Nxt
)
3582 and then Is_Statement
(Nxt
)
3584 -- Special very annoying exception. If we have a return that
3585 -- follows a raise, then we allow it without a warning, since
3586 -- the Ada RM annoyingly requires a useless return here.
3588 if Nkind
(Original_Node
(N
)) /= N_Raise_Statement
3589 or else Nkind
(Nxt
) /= N_Simple_Return_Statement
3591 -- The rather strange shenanigans with the warning message
3592 -- here reflects the fact that Kill_Dead_Code is very good
3593 -- at removing warnings in deleted code, and this is one
3594 -- warning we would prefer NOT to have removed.
3598 -- If we have unreachable code, analyze and remove the
3599 -- unreachable code, since it is useless and we don't
3600 -- want to generate junk warnings.
3602 -- We skip this step if we are not in code generation mode
3603 -- or CodePeer mode.
3605 -- This is the one case where we remove dead code in the
3606 -- semantics as opposed to the expander, and we do not want
3607 -- to remove code if we are not in code generation mode,
3608 -- since this messes up the ASIS trees or loses useful
3609 -- information in the CodePeer tree.
3611 -- Note that one might react by moving the whole circuit to
3612 -- exp_ch5, but then we lose the warning in -gnatc mode.
3614 if Operating_Mode
= Generate_Code
3615 and then not CodePeer_Mode
3620 -- Quit deleting when we have nothing more to delete
3621 -- or if we hit a label (since someone could transfer
3622 -- control to a label, so we should not delete it).
3624 exit when No
(Nxt
) or else Nkind
(Nxt
) = N_Label
;
3626 -- Statement/declaration is to be deleted
3630 Kill_Dead_Code
(Nxt
);
3634 -- Now issue the warning (or error in formal mode)
3636 if Restriction_Check_Required
(SPARK_05
) then
3637 Check_SPARK_05_Restriction
3638 ("unreachable code is not allowed", Error_Node
);
3640 Error_Msg
("??unreachable code!", Sloc
(Error_Node
));
3644 -- If the unconditional transfer of control instruction is the
3645 -- last statement of a sequence, then see if our parent is one of
3646 -- the constructs for which we count unblocked exits, and if so,
3647 -- adjust the count.
3652 -- Statements in THEN part or ELSE part of IF statement
3654 if Nkind
(P
) = N_If_Statement
then
3657 -- Statements in ELSIF part of an IF statement
3659 elsif Nkind
(P
) = N_Elsif_Part
then
3661 pragma Assert
(Nkind
(P
) = N_If_Statement
);
3663 -- Statements in CASE statement alternative
3665 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
3667 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
3669 -- Statements in body of block
3671 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
3672 and then Nkind
(Parent
(P
)) = N_Block_Statement
3674 -- The original loop is now placed inside a block statement
3675 -- due to the expansion of attribute 'Loop_Entry. Return as
3676 -- this is not a "real" block for the purposes of exit
3679 if Nkind
(N
) = N_Loop_Statement
3680 and then Subject_To_Loop_Entry_Attributes
(N
)
3685 -- Statements in exception handler in a block
3687 elsif Nkind
(P
) = N_Exception_Handler
3688 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
3689 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
3693 -- None of these cases, so return
3699 -- This was one of the cases we are looking for (i.e. the
3700 -- parent construct was IF, CASE or block) so decrement count.
3702 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
3706 end Check_Unreachable_Code
;
3708 ----------------------
3709 -- Preanalyze_Range --
3710 ----------------------
3712 procedure Preanalyze_Range
(R_Copy
: Node_Id
) is
3713 Save_Analysis
: constant Boolean := Full_Analysis
;
3717 Full_Analysis
:= False;
3718 Expander_Mode_Save_And_Set
(False);
3722 if Nkind
(R_Copy
) in N_Subexpr
and then Is_Overloaded
(R_Copy
) then
3724 -- Apply preference rules for range of predefined integer types, or
3725 -- diagnose true ambiguity.
3730 Found
: Entity_Id
:= Empty
;
3733 Get_First_Interp
(R_Copy
, I
, It
);
3734 while Present
(It
.Typ
) loop
3735 if Is_Discrete_Type
(It
.Typ
) then
3739 if Scope
(Found
) = Standard_Standard
then
3742 elsif Scope
(It
.Typ
) = Standard_Standard
then
3746 -- Both of them are user-defined
3749 ("ambiguous bounds in range of iteration", R_Copy
);
3750 Error_Msg_N
("\possible interpretations:", R_Copy
);
3751 Error_Msg_NE
("\\} ", R_Copy
, Found
);
3752 Error_Msg_NE
("\\} ", R_Copy
, It
.Typ
);
3758 Get_Next_Interp
(I
, It
);
3763 -- Subtype mark in iteration scheme
3765 if Is_Entity_Name
(R_Copy
) and then Is_Type
(Entity
(R_Copy
)) then
3768 -- Expression in range, or Ada 2012 iterator
3770 elsif Nkind
(R_Copy
) in N_Subexpr
then
3772 Typ
:= Etype
(R_Copy
);
3774 if Is_Discrete_Type
(Typ
) then
3777 -- Check that the resulting object is an iterable container
3779 elsif Has_Aspect
(Typ
, Aspect_Iterator_Element
)
3780 or else Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
3781 or else Has_Aspect
(Typ
, Aspect_Variable_Indexing
)
3785 -- The expression may yield an implicit reference to an iterable
3786 -- container. Insert explicit dereference so that proper type is
3787 -- visible in the loop.
3789 elsif Has_Implicit_Dereference
(Etype
(R_Copy
)) then
3794 Disc
:= First_Discriminant
(Typ
);
3795 while Present
(Disc
) loop
3796 if Has_Implicit_Dereference
(Disc
) then
3797 Build_Explicit_Dereference
(R_Copy
, Disc
);
3801 Next_Discriminant
(Disc
);
3808 Expander_Mode_Restore
;
3809 Full_Analysis
:= Save_Analysis
;
3810 end Preanalyze_Range
;