1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2016, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Errout
; use Errout
;
31 with Expander
; use Expander
;
32 with Exp_Ch6
; use Exp_Ch6
;
33 with Exp_Util
; use Exp_Util
;
34 with Freeze
; use Freeze
;
35 with Ghost
; use Ghost
;
37 with Lib
.Xref
; use Lib
.Xref
;
38 with Namet
; use Namet
;
39 with Nlists
; use Nlists
;
40 with Nmake
; use Nmake
;
42 with Restrict
; use Restrict
;
43 with Rident
; use Rident
;
45 with Sem_Aux
; use Sem_Aux
;
46 with Sem_Case
; use Sem_Case
;
47 with Sem_Ch3
; use Sem_Ch3
;
48 with Sem_Ch6
; use Sem_Ch6
;
49 with Sem_Ch8
; use Sem_Ch8
;
50 with Sem_Dim
; use Sem_Dim
;
51 with Sem_Disp
; use Sem_Disp
;
52 with Sem_Elab
; use Sem_Elab
;
53 with Sem_Eval
; use Sem_Eval
;
54 with Sem_Res
; use Sem_Res
;
55 with Sem_Type
; use Sem_Type
;
56 with Sem_Util
; use Sem_Util
;
57 with Sem_Warn
; use Sem_Warn
;
58 with Snames
; use Snames
;
59 with Stand
; use Stand
;
60 with Sinfo
; use Sinfo
;
61 with Targparm
; use Targparm
;
62 with Tbuild
; use Tbuild
;
63 with Uintp
; use Uintp
;
65 package body Sem_Ch5
is
67 Unblocked_Exit_Count
: Nat
:= 0;
68 -- This variable is used when processing if statements, case statements,
69 -- and block statements. It counts the number of exit points that are not
70 -- blocked by unconditional transfer instructions: for IF and CASE, these
71 -- are the branches of the conditional; for a block, they are the statement
72 -- sequence of the block, and the statement sequences of any exception
73 -- handlers that are part of the block. When processing is complete, if
74 -- this count is zero, it means that control cannot fall through the IF,
75 -- CASE or block statement. This is used for the generation of warning
76 -- messages. This variable is recursively saved on entry to processing the
77 -- construct, and restored on exit.
79 procedure Preanalyze_Range
(R_Copy
: Node_Id
);
80 -- Determine expected type of range or domain of iteration of Ada 2012
81 -- loop by analyzing separate copy. Do the analysis and resolution of the
82 -- copy of the bound(s) with expansion disabled, to prevent the generation
83 -- of finalization actions. This prevents memory leaks when the bounds
84 -- contain calls to functions returning controlled arrays or when the
85 -- domain of iteration is a container.
87 ------------------------
88 -- Analyze_Assignment --
89 ------------------------
91 procedure Analyze_Assignment
(N
: Node_Id
) is
92 Lhs
: constant Node_Id
:= Name
(N
);
93 Rhs
: constant Node_Id
:= Expression
(N
);
98 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
);
99 -- N is the node for the left hand side of an assignment, and it is not
100 -- a variable. This routine issues an appropriate diagnostic.
103 -- This is called to kill current value settings of a simple variable
104 -- on the left hand side. We call it if we find any error in analyzing
105 -- the assignment, and at the end of processing before setting any new
106 -- current values in place.
108 procedure Set_Assignment_Type
110 Opnd_Type
: in out Entity_Id
);
111 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
112 -- nominal subtype. This procedure is used to deal with cases where the
113 -- nominal subtype must be replaced by the actual subtype.
115 -------------------------------
116 -- Diagnose_Non_Variable_Lhs --
117 -------------------------------
119 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
121 -- Not worth posting another error if left hand side already flagged
122 -- as being illegal in some respect.
124 if Error_Posted
(N
) then
127 -- Some special bad cases of entity names
129 elsif Is_Entity_Name
(N
) then
131 Ent
: constant Entity_Id
:= Entity
(N
);
134 if Ekind
(Ent
) = E_In_Parameter
then
136 ("assignment to IN mode parameter not allowed", N
);
139 -- Renamings of protected private components are turned into
140 -- constants when compiling a protected function. In the case
141 -- of single protected types, the private component appears
144 elsif (Is_Prival
(Ent
)
146 (Ekind
(Current_Scope
) = E_Function
147 or else Ekind
(Enclosing_Dynamic_Scope
148 (Current_Scope
)) = E_Function
))
150 (Ekind
(Ent
) = E_Component
151 and then Is_Protected_Type
(Scope
(Ent
)))
154 ("protected function cannot modify protected object", N
);
157 elsif Ekind
(Ent
) = E_Loop_Parameter
then
158 Error_Msg_N
("assignment to loop parameter not allowed", N
);
163 -- For indexed components, test prefix if it is in array. We do not
164 -- want to recurse for cases where the prefix is a pointer, since we
165 -- may get a message confusing the pointer and what it references.
167 elsif Nkind
(N
) = N_Indexed_Component
168 and then Is_Array_Type
(Etype
(Prefix
(N
)))
170 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
173 -- Another special case for assignment to discriminant
175 elsif Nkind
(N
) = N_Selected_Component
then
176 if Present
(Entity
(Selector_Name
(N
)))
177 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
179 Error_Msg_N
("assignment to discriminant not allowed", N
);
182 -- For selection from record, diagnose prefix, but note that again
183 -- we only do this for a record, not e.g. for a pointer.
185 elsif Is_Record_Type
(Etype
(Prefix
(N
))) then
186 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
191 -- If we fall through, we have no special message to issue
193 Error_Msg_N
("left hand side of assignment must be a variable", N
);
194 end Diagnose_Non_Variable_Lhs
;
200 procedure Kill_Lhs
is
202 if Is_Entity_Name
(Lhs
) then
204 Ent
: constant Entity_Id
:= Entity
(Lhs
);
206 if Present
(Ent
) then
207 Kill_Current_Values
(Ent
);
213 -------------------------
214 -- Set_Assignment_Type --
215 -------------------------
217 procedure Set_Assignment_Type
219 Opnd_Type
: in out Entity_Id
)
222 Require_Entity
(Opnd
);
224 -- If the assignment operand is an in-out or out parameter, then we
225 -- get the actual subtype (needed for the unconstrained case). If the
226 -- operand is the actual in an entry declaration, then within the
227 -- accept statement it is replaced with a local renaming, which may
228 -- also have an actual subtype.
230 if Is_Entity_Name
(Opnd
)
231 and then (Ekind
(Entity
(Opnd
)) = E_Out_Parameter
232 or else Ekind_In
(Entity
(Opnd
),
234 E_Generic_In_Out_Parameter
)
236 (Ekind
(Entity
(Opnd
)) = E_Variable
237 and then Nkind
(Parent
(Entity
(Opnd
))) =
238 N_Object_Renaming_Declaration
239 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
242 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
244 -- If assignment operand is a component reference, then we get the
245 -- actual subtype of the component for the unconstrained case.
247 elsif Nkind_In
(Opnd
, N_Selected_Component
, N_Explicit_Dereference
)
248 and then not Is_Unchecked_Union
(Opnd_Type
)
250 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
252 if Present
(Decl
) then
253 Insert_Action
(N
, Decl
);
254 Mark_Rewrite_Insertion
(Decl
);
256 Opnd_Type
:= Defining_Identifier
(Decl
);
257 Set_Etype
(Opnd
, Opnd_Type
);
258 Freeze_Itype
(Opnd_Type
, N
);
260 elsif Is_Constrained
(Etype
(Opnd
)) then
261 Opnd_Type
:= Etype
(Opnd
);
264 -- For slice, use the constrained subtype created for the slice
266 elsif Nkind
(Opnd
) = N_Slice
then
267 Opnd_Type
:= Etype
(Opnd
);
269 end Set_Assignment_Type
;
273 Save_Ghost_Mode
: constant Ghost_Mode_Type
:= Ghost_Mode
;
275 -- Start of processing for Analyze_Assignment
278 Mark_Coextensions
(N
, Rhs
);
280 -- Analyze the target of the assignment first in case the expression
281 -- contains references to Ghost entities. The checks that verify the
282 -- proper use of a Ghost entity need to know the enclosing context.
286 -- An assignment statement is Ghost when the left hand side denotes a
287 -- Ghost entity. Set the mode now to ensure that any nodes generated
288 -- during analysis and expansion are properly marked as Ghost.
293 -- Ensure that we never do an assignment on a variable marked as
294 -- as Safe_To_Reevaluate.
296 pragma Assert
(not Is_Entity_Name
(Lhs
)
297 or else Ekind
(Entity
(Lhs
)) /= E_Variable
298 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
300 -- Start type analysis for assignment
304 -- In the most general case, both Lhs and Rhs can be overloaded, and we
305 -- must compute the intersection of the possible types on each side.
307 if Is_Overloaded
(Lhs
) then
314 Get_First_Interp
(Lhs
, I
, It
);
316 while Present
(It
.Typ
) loop
318 -- An indexed component with generalized indexing is always
319 -- overloaded with the corresponding dereference. Discard the
320 -- interpretation that yields a reference type, which is not
323 if Nkind
(Lhs
) = N_Indexed_Component
324 and then Present
(Generalized_Indexing
(Lhs
))
325 and then Has_Implicit_Dereference
(It
.Typ
)
329 elsif Has_Compatible_Type
(Rhs
, It
.Typ
) then
330 if T1
/= Any_Type
then
332 -- An explicit dereference is overloaded if the prefix
333 -- is. Try to remove the ambiguity on the prefix, the
334 -- error will be posted there if the ambiguity is real.
336 if Nkind
(Lhs
) = N_Explicit_Dereference
then
339 PI1
: Interp_Index
:= 0;
345 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
347 while Present
(PIt
.Typ
) loop
348 if Is_Access_Type
(PIt
.Typ
)
349 and then Has_Compatible_Type
350 (Rhs
, Designated_Type
(PIt
.Typ
))
354 Disambiguate
(Prefix
(Lhs
),
357 if PIt
= No_Interp
then
359 ("ambiguous left-hand side"
360 & " in assignment", Lhs
);
363 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
373 Get_Next_Interp
(PI
, PIt
);
379 ("ambiguous left-hand side in assignment", Lhs
);
387 Get_Next_Interp
(I
, It
);
391 if T1
= Any_Type
then
393 ("no valid types for left-hand side for assignment", Lhs
);
395 Ghost_Mode
:= Save_Ghost_Mode
;
400 -- The resulting assignment type is T1, so now we will resolve the left
401 -- hand side of the assignment using this determined type.
405 -- Cases where Lhs is not a variable
407 -- Cases where Lhs is not a variable. In an instance or an inlined body
408 -- no need for further check because assignment was legal in template.
410 if In_Inlined_Body
then
413 elsif not Is_Variable
(Lhs
) then
415 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
423 if Ada_Version
>= Ada_2005
then
425 -- Handle chains of renamings
428 while Nkind
(Ent
) in N_Has_Entity
429 and then Present
(Entity
(Ent
))
430 and then Present
(Renamed_Object
(Entity
(Ent
)))
432 Ent
:= Renamed_Object
(Entity
(Ent
));
435 if (Nkind
(Ent
) = N_Attribute_Reference
436 and then Attribute_Name
(Ent
) = Name_Priority
)
438 -- Renamings of the attribute Priority applied to protected
439 -- objects have been previously expanded into calls to the
440 -- Get_Ceiling run-time subprogram.
442 or else Is_Expanded_Priority_Attribute
(Ent
)
444 -- The enclosing subprogram cannot be a protected function
447 while not (Is_Subprogram
(S
)
448 and then Convention
(S
) = Convention_Protected
)
449 and then S
/= Standard_Standard
454 if Ekind
(S
) = E_Function
455 and then Convention
(S
) = Convention_Protected
458 ("protected function cannot modify protected object",
462 -- Changes of the ceiling priority of the protected object
463 -- are only effective if the Ceiling_Locking policy is in
464 -- effect (AARM D.5.2 (5/2)).
466 if Locking_Policy
/= 'C' then
467 Error_Msg_N
("assignment to the attribute PRIORITY has " &
469 Error_Msg_N
("\since no Locking_Policy has been " &
473 Ghost_Mode
:= Save_Ghost_Mode
;
479 Diagnose_Non_Variable_Lhs
(Lhs
);
480 Ghost_Mode
:= Save_Ghost_Mode
;
483 -- Error of assigning to limited type. We do however allow this in
484 -- certain cases where the front end generates the assignments.
486 elsif Is_Limited_Type
(T1
)
487 and then not Assignment_OK
(Lhs
)
488 and then not Assignment_OK
(Original_Node
(Lhs
))
490 -- CPP constructors can only be called in declarations
492 if Is_CPP_Constructor_Call
(Rhs
) then
493 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
496 ("left hand of assignment must not be limited type", Lhs
);
497 Explain_Limited_Type
(T1
, Lhs
);
500 Ghost_Mode
:= Save_Ghost_Mode
;
503 -- A class-wide type may be a limited view. This illegal case is not
504 -- caught by previous checks.
506 elsif Ekind
(T1
) = E_Class_Wide_Type
507 and then From_Limited_With
(T1
)
509 Error_Msg_NE
("invalid use of limited view of&", Lhs
, T1
);
512 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
513 -- abstract. This is only checked when the assignment Comes_From_Source,
514 -- because in some cases the expander generates such assignments (such
515 -- in the _assign operation for an abstract type).
517 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
519 ("target of assignment operation must not be abstract", Lhs
);
522 -- Resolution may have updated the subtype, in case the left-hand side
523 -- is a private protected component. Use the correct subtype to avoid
524 -- scoping issues in the back-end.
528 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
529 -- type. For example:
533 -- type Acc is access P.T;
536 -- with Pkg; use Acc;
537 -- procedure Example is
540 -- A.all := B.all; -- ERROR
543 if Nkind
(Lhs
) = N_Explicit_Dereference
544 and then Ekind
(T1
) = E_Incomplete_Type
546 Error_Msg_N
("invalid use of incomplete type", Lhs
);
548 Ghost_Mode
:= Save_Ghost_Mode
;
552 -- Now we can complete the resolution of the right hand side
554 Set_Assignment_Type
(Lhs
, T1
);
557 -- This is the point at which we check for an unset reference
559 Check_Unset_Reference
(Rhs
);
560 Check_Unprotected_Access
(Lhs
, Rhs
);
562 -- Remaining steps are skipped if Rhs was syntactically in error
566 Ghost_Mode
:= Save_Ghost_Mode
;
572 if not Covers
(T1
, T2
) then
573 Wrong_Type
(Rhs
, Etype
(Lhs
));
575 Ghost_Mode
:= Save_Ghost_Mode
;
579 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
580 -- types, use the non-limited view if available
582 if Nkind
(Rhs
) = N_Explicit_Dereference
583 and then Is_Tagged_Type
(T2
)
584 and then Has_Non_Limited_View
(T2
)
586 T2
:= Non_Limited_View
(T2
);
589 Set_Assignment_Type
(Rhs
, T2
);
591 if Total_Errors_Detected
/= 0 then
601 if T1
= Any_Type
or else T2
= Any_Type
then
603 Ghost_Mode
:= Save_Ghost_Mode
;
607 -- If the rhs is class-wide or dynamically tagged, then require the lhs
608 -- to be class-wide. The case where the rhs is a dynamically tagged call
609 -- to a dispatching operation with a controlling access result is
610 -- excluded from this check, since the target has an access type (and
611 -- no tag propagation occurs in that case).
613 if (Is_Class_Wide_Type
(T2
)
614 or else (Is_Dynamically_Tagged
(Rhs
)
615 and then not Is_Access_Type
(T1
)))
616 and then not Is_Class_Wide_Type
(T1
)
618 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
620 elsif Is_Class_Wide_Type
(T1
)
621 and then not Is_Class_Wide_Type
(T2
)
622 and then not Is_Tag_Indeterminate
(Rhs
)
623 and then not Is_Dynamically_Tagged
(Rhs
)
625 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
628 -- Propagate the tag from a class-wide target to the rhs when the rhs
629 -- is a tag-indeterminate call.
631 if Is_Tag_Indeterminate
(Rhs
) then
632 if Is_Class_Wide_Type
(T1
) then
633 Propagate_Tag
(Lhs
, Rhs
);
635 elsif Nkind
(Rhs
) = N_Function_Call
636 and then Is_Entity_Name
(Name
(Rhs
))
637 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
640 ("call to abstract function must be dispatching", Name
(Rhs
));
642 elsif Nkind
(Rhs
) = N_Qualified_Expression
643 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
644 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
646 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
649 ("call to abstract function must be dispatching",
650 Name
(Expression
(Rhs
)));
654 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
655 -- apply an implicit conversion of the rhs to that type to force
656 -- appropriate static and run-time accessibility checks. This applies
657 -- as well to anonymous access-to-subprogram types that are component
658 -- subtypes or formal parameters.
660 if Ada_Version
>= Ada_2005
and then Is_Access_Type
(T1
) then
661 if Is_Local_Anonymous_Access
(T1
)
662 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
664 -- Handle assignment to an Ada 2012 stand-alone object
665 -- of an anonymous access type.
667 or else (Ekind
(T1
) = E_Anonymous_Access_Type
668 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
669 N_Object_Declaration
)
672 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
673 Analyze_And_Resolve
(Rhs
, T1
);
677 -- Ada 2005 (AI-231): Assignment to not null variable
679 if Ada_Version
>= Ada_2005
680 and then Can_Never_Be_Null
(T1
)
681 and then not Assignment_OK
(Lhs
)
683 -- Case where we know the right hand side is null
685 if Known_Null
(Rhs
) then
686 Apply_Compile_Time_Constraint_Error
689 "(Ada 2005) null not allowed in null-excluding objects??",
690 Reason
=> CE_Null_Not_Allowed
);
692 -- We still mark this as a possible modification, that's necessary
693 -- to reset Is_True_Constant, and desirable for xref purposes.
695 Note_Possible_Modification
(Lhs
, Sure
=> True);
696 Ghost_Mode
:= Save_Ghost_Mode
;
699 -- If we know the right hand side is non-null, then we convert to the
700 -- target type, since we don't need a run time check in that case.
702 elsif not Can_Never_Be_Null
(T2
) then
703 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
704 Analyze_And_Resolve
(Rhs
, T1
);
708 if Is_Scalar_Type
(T1
) then
709 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
711 -- For array types, verify that lengths match. If the right hand side
712 -- is a function call that has been inlined, the assignment has been
713 -- rewritten as a block, and the constraint check will be applied to the
714 -- assignment within the block.
716 elsif Is_Array_Type
(T1
)
717 and then (Nkind
(Rhs
) /= N_Type_Conversion
718 or else Is_Constrained
(Etype
(Rhs
)))
719 and then (Nkind
(Rhs
) /= N_Function_Call
720 or else Nkind
(N
) /= N_Block_Statement
)
722 -- Assignment verifies that the length of the Lsh and Rhs are equal,
723 -- but of course the indexes do not have to match. If the right-hand
724 -- side is a type conversion to an unconstrained type, a length check
725 -- is performed on the expression itself during expansion. In rare
726 -- cases, the redundant length check is computed on an index type
727 -- with a different representation, triggering incorrect code in the
730 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
733 -- Discriminant checks are applied in the course of expansion
738 -- Note: modifications of the Lhs may only be recorded after
739 -- checks have been applied.
741 Note_Possible_Modification
(Lhs
, Sure
=> True);
743 -- ??? a real accessibility check is needed when ???
745 -- Post warning for redundant assignment or variable to itself
747 if Warn_On_Redundant_Constructs
749 -- We only warn for source constructs
751 and then Comes_From_Source
(N
)
753 -- Where the object is the same on both sides
755 and then Same_Object
(Lhs
, Original_Node
(Rhs
))
757 -- But exclude the case where the right side was an operation that
758 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
759 -- don't want to warn in such a case, since it is reasonable to write
760 -- such expressions especially when K is defined symbolically in some
763 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
765 if Nkind
(Lhs
) in N_Has_Entity
then
766 Error_Msg_NE
-- CODEFIX
767 ("?r?useless assignment of & to itself!", N
, Entity
(Lhs
));
769 Error_Msg_N
-- CODEFIX
770 ("?r?useless assignment of object to itself!", N
);
774 -- Check for non-allowed composite assignment
776 if not Support_Composite_Assign_On_Target
777 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
778 and then (not Has_Size_Clause
(T1
) or else Esize
(T1
) > 64)
780 Error_Msg_CRT
("composite assignment", N
);
783 -- Check elaboration warning for left side if not in elab code
785 if not In_Subprogram_Or_Concurrent_Unit
then
786 Check_Elab_Assign
(Lhs
);
789 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
790 -- assignment is a source assignment in the extended main source unit.
791 -- We are not interested in any reference information outside this
792 -- context, or in compiler generated assignment statements.
794 if Comes_From_Source
(N
)
795 and then In_Extended_Main_Source_Unit
(Lhs
)
797 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
800 -- RM 7.3.2 (12/3): An assignment to a view conversion (from a type
801 -- to one of its ancestors) requires an invariant check. Apply check
802 -- only if expression comes from source, otherwise it will be applied
803 -- when value is assigned to source entity.
805 if Nkind
(Lhs
) = N_Type_Conversion
806 and then Has_Invariants
(Etype
(Expression
(Lhs
)))
807 and then Comes_From_Source
(Expression
(Lhs
))
809 Insert_After
(N
, Make_Invariant_Call
(Expression
(Lhs
)));
812 -- Final step. If left side is an entity, then we may be able to reset
813 -- the current tracked values to new safe values. We only have something
814 -- to do if the left side is an entity name, and expansion has not
815 -- modified the node into something other than an assignment, and of
816 -- course we only capture values if it is safe to do so.
818 if Is_Entity_Name
(Lhs
)
819 and then Nkind
(N
) = N_Assignment_Statement
822 Ent
: constant Entity_Id
:= Entity
(Lhs
);
825 if Safe_To_Capture_Value
(N
, Ent
) then
827 -- If simple variable on left side, warn if this assignment
828 -- blots out another one (rendering it useless). We only do
829 -- this for source assignments, otherwise we can generate bogus
830 -- warnings when an assignment is rewritten as another
831 -- assignment, and gets tied up with itself.
833 if Warn_On_Modified_Unread
834 and then Is_Assignable
(Ent
)
835 and then Comes_From_Source
(N
)
836 and then In_Extended_Main_Source_Unit
(Ent
)
838 Warn_On_Useless_Assignment
(Ent
, N
);
841 -- If we are assigning an access type and the left side is an
842 -- entity, then make sure that the Is_Known_[Non_]Null flags
843 -- properly reflect the state of the entity after assignment.
845 if Is_Access_Type
(T1
) then
846 if Known_Non_Null
(Rhs
) then
847 Set_Is_Known_Non_Null
(Ent
, True);
849 elsif Known_Null
(Rhs
)
850 and then not Can_Never_Be_Null
(Ent
)
852 Set_Is_Known_Null
(Ent
, True);
855 Set_Is_Known_Null
(Ent
, False);
857 if not Can_Never_Be_Null
(Ent
) then
858 Set_Is_Known_Non_Null
(Ent
, False);
862 -- For discrete types, we may be able to set the current value
863 -- if the value is known at compile time.
865 elsif Is_Discrete_Type
(T1
)
866 and then Compile_Time_Known_Value
(Rhs
)
868 Set_Current_Value
(Ent
, Rhs
);
870 Set_Current_Value
(Ent
, Empty
);
873 -- If not safe to capture values, kill them
881 -- If assigning to an object in whole or in part, note location of
882 -- assignment in case no one references value. We only do this for
883 -- source assignments, otherwise we can generate bogus warnings when an
884 -- assignment is rewritten as another assignment, and gets tied up with
888 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
891 and then Safe_To_Capture_Value
(N
, Ent
)
892 and then Nkind
(N
) = N_Assignment_Statement
893 and then Warn_On_Modified_Unread
894 and then Is_Assignable
(Ent
)
895 and then Comes_From_Source
(N
)
896 and then In_Extended_Main_Source_Unit
(Ent
)
898 Set_Last_Assignment
(Ent
, Lhs
);
902 Analyze_Dimension
(N
);
903 Ghost_Mode
:= Save_Ghost_Mode
;
904 end Analyze_Assignment
;
906 -----------------------------
907 -- Analyze_Block_Statement --
908 -----------------------------
910 procedure Analyze_Block_Statement
(N
: Node_Id
) is
911 procedure Install_Return_Entities
(Scop
: Entity_Id
);
912 -- Install all entities of return statement scope Scop in the visibility
913 -- chain except for the return object since its entity is reused in a
916 -----------------------------
917 -- Install_Return_Entities --
918 -----------------------------
920 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
924 Id
:= First_Entity
(Scop
);
925 while Present
(Id
) loop
927 -- Do not install the return object
929 if not Ekind_In
(Id
, E_Constant
, E_Variable
)
930 or else not Is_Return_Object
(Id
)
937 end Install_Return_Entities
;
939 -- Local constants and variables
941 Decls
: constant List_Id
:= Declarations
(N
);
942 Id
: constant Node_Id
:= Identifier
(N
);
943 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
945 Is_BIP_Return_Statement
: Boolean;
947 -- Start of processing for Analyze_Block_Statement
950 -- In SPARK mode, we reject block statements. Note that the case of
951 -- block statements generated by the expander is fine.
953 if Nkind
(Original_Node
(N
)) = N_Block_Statement
then
954 Check_SPARK_05_Restriction
("block statement is not allowed", N
);
957 -- If no handled statement sequence is present, things are really messed
958 -- up, and we just return immediately (defence against previous errors).
961 Check_Error_Detected
;
965 -- Detect whether the block is actually a rewritten return statement of
966 -- a build-in-place function.
968 Is_BIP_Return_Statement
:=
970 and then Present
(Entity
(Id
))
971 and then Ekind
(Entity
(Id
)) = E_Return_Statement
972 and then Is_Build_In_Place_Function
973 (Return_Applies_To
(Entity
(Id
)));
975 -- Normal processing with HSS present
978 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
979 Ent
: Entity_Id
:= Empty
;
982 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
983 -- Recursively save value of this global, will be restored on exit
986 -- Initialize unblocked exit count for statements of begin block
987 -- plus one for each exception handler that is present.
989 Unblocked_Exit_Count
:= 1;
992 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ List_Length
(EH
);
995 -- If a label is present analyze it and mark it as referenced
1001 -- An error defense. If we have an identifier, but no entity, then
1002 -- something is wrong. If previous errors, then just remove the
1003 -- identifier and continue, otherwise raise an exception.
1006 Check_Error_Detected
;
1007 Set_Identifier
(N
, Empty
);
1010 Set_Ekind
(Ent
, E_Block
);
1011 Generate_Reference
(Ent
, N
, ' ');
1012 Generate_Definition
(Ent
);
1014 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
1015 Set_Label_Construct
(Parent
(Ent
), N
);
1020 -- If no entity set, create a label entity
1023 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
1024 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
1025 Set_Parent
(Ent
, N
);
1028 Set_Etype
(Ent
, Standard_Void_Type
);
1029 Set_Block_Node
(Ent
, Identifier
(N
));
1032 -- The block served as an extended return statement. Ensure that any
1033 -- entities created during the analysis and expansion of the return
1034 -- object declaration are once again visible.
1036 if Is_BIP_Return_Statement
then
1037 Install_Return_Entities
(Ent
);
1040 if Present
(Decls
) then
1041 Analyze_Declarations
(Decls
);
1043 Inspect_Deferred_Constant_Completion
(Decls
);
1047 Process_End_Label
(HSS
, 'e', Ent
);
1049 -- If exception handlers are present, then we indicate that enclosing
1050 -- scopes contain a block with handlers. We only need to mark non-
1053 if Present
(EH
) then
1056 Set_Has_Nested_Block_With_Handler
(S
);
1057 exit when Is_Overloadable
(S
)
1058 or else Ekind
(S
) = E_Package
1059 or else Is_Generic_Unit
(S
);
1064 Check_References
(Ent
);
1067 if Unblocked_Exit_Count
= 0 then
1068 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1069 Check_Unreachable_Code
(N
);
1071 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1074 end Analyze_Block_Statement
;
1076 --------------------------------
1077 -- Analyze_Compound_Statement --
1078 --------------------------------
1080 procedure Analyze_Compound_Statement
(N
: Node_Id
) is
1082 Analyze_List
(Actions
(N
));
1083 end Analyze_Compound_Statement
;
1085 ----------------------------
1086 -- Analyze_Case_Statement --
1087 ----------------------------
1089 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1091 Exp_Type
: Entity_Id
;
1092 Exp_Btype
: Entity_Id
;
1095 Others_Present
: Boolean;
1096 -- Indicates if Others was present
1098 pragma Warnings
(Off
, Last_Choice
);
1099 -- Don't care about assigned value
1101 Statements_Analyzed
: Boolean := False;
1102 -- Set True if at least some statement sequences get analyzed. If False
1103 -- on exit, means we had a serious error that prevented full analysis of
1104 -- the case statement, and as a result it is not a good idea to output
1105 -- warning messages about unreachable code.
1107 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1108 -- Recursively save value of this global, will be restored on exit
1110 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1111 -- Error routine invoked by the generic instantiation below when the
1112 -- case statement has a non static choice.
1114 procedure Process_Statements
(Alternative
: Node_Id
);
1115 -- Analyzes the statements associated with a case alternative. Needed
1116 -- by instantiation below.
1118 package Analyze_Case_Choices
is new
1119 Generic_Analyze_Choices
1120 (Process_Associated_Node
=> Process_Statements
);
1121 use Analyze_Case_Choices
;
1122 -- Instantiation of the generic choice analysis package
1124 package Check_Case_Choices
is new
1125 Generic_Check_Choices
1126 (Process_Empty_Choice
=> No_OP
,
1127 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1128 Process_Associated_Node
=> No_OP
);
1129 use Check_Case_Choices
;
1130 -- Instantiation of the generic choice processing package
1132 -----------------------------
1133 -- Non_Static_Choice_Error --
1134 -----------------------------
1136 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1138 Flag_Non_Static_Expr
1139 ("choice given in case statement is not static!", Choice
);
1140 end Non_Static_Choice_Error
;
1142 ------------------------
1143 -- Process_Statements --
1144 ------------------------
1146 procedure Process_Statements
(Alternative
: Node_Id
) is
1147 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1151 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1152 Statements_Analyzed
:= True;
1154 -- An interesting optimization. If the case statement expression
1155 -- is a simple entity, then we can set the current value within an
1156 -- alternative if the alternative has one possible value.
1160 -- when 2 | 3 => beta
1161 -- when others => gamma
1163 -- Here we know that N is initially 1 within alpha, but for beta and
1164 -- gamma, we do not know anything more about the initial value.
1166 if Is_Entity_Name
(Exp
) then
1167 Ent
:= Entity
(Exp
);
1169 if Ekind_In
(Ent
, E_Variable
,
1173 if List_Length
(Choices
) = 1
1174 and then Nkind
(First
(Choices
)) in N_Subexpr
1175 and then Compile_Time_Known_Value
(First
(Choices
))
1177 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1180 Analyze_Statements
(Statements
(Alternative
));
1182 -- After analyzing the case, set the current value to empty
1183 -- since we won't know what it is for the next alternative
1184 -- (unless reset by this same circuit), or after the case.
1186 Set_Current_Value
(Entity
(Exp
), Empty
);
1191 -- Case where expression is not an entity name of a variable
1193 Analyze_Statements
(Statements
(Alternative
));
1194 end Process_Statements
;
1196 -- Start of processing for Analyze_Case_Statement
1199 Unblocked_Exit_Count
:= 0;
1200 Exp
:= Expression
(N
);
1203 -- The expression must be of any discrete type. In rare cases, the
1204 -- expander constructs a case statement whose expression has a private
1205 -- type whose full view is discrete. This can happen when generating
1206 -- a stream operation for a variant type after the type is frozen,
1207 -- when the partial of view of the type of the discriminant is private.
1208 -- In that case, use the full view to analyze case alternatives.
1210 if not Is_Overloaded
(Exp
)
1211 and then not Comes_From_Source
(N
)
1212 and then Is_Private_Type
(Etype
(Exp
))
1213 and then Present
(Full_View
(Etype
(Exp
)))
1214 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1216 Resolve
(Exp
, Etype
(Exp
));
1217 Exp_Type
:= Full_View
(Etype
(Exp
));
1220 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1221 Exp_Type
:= Etype
(Exp
);
1224 Check_Unset_Reference
(Exp
);
1225 Exp_Btype
:= Base_Type
(Exp_Type
);
1227 -- The expression must be of a discrete type which must be determinable
1228 -- independently of the context in which the expression occurs, but
1229 -- using the fact that the expression must be of a discrete type.
1230 -- Moreover, the type this expression must not be a character literal
1231 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1233 -- If error already reported by Resolve, nothing more to do
1235 if Exp_Btype
= Any_Discrete
or else Exp_Btype
= Any_Type
then
1238 elsif Exp_Btype
= Any_Character
then
1240 ("character literal as case expression is ambiguous", Exp
);
1243 elsif Ada_Version
= Ada_83
1244 and then (Is_Generic_Type
(Exp_Btype
)
1245 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1248 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1252 -- If the case expression is a formal object of mode in out, then treat
1253 -- it as having a nonstatic subtype by forcing use of the base type
1254 -- (which has to get passed to Check_Case_Choices below). Also use base
1255 -- type when the case expression is parenthesized.
1257 if Paren_Count
(Exp
) > 0
1258 or else (Is_Entity_Name
(Exp
)
1259 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1261 Exp_Type
:= Exp_Btype
;
1264 -- Call instantiated procedures to analyzwe and check discrete choices
1266 Analyze_Choices
(Alternatives
(N
), Exp_Type
);
1267 Check_Choices
(N
, Alternatives
(N
), Exp_Type
, Others_Present
);
1269 -- Case statement with single OTHERS alternative not allowed in SPARK
1271 if Others_Present
and then List_Length
(Alternatives
(N
)) = 1 then
1272 Check_SPARK_05_Restriction
1273 ("OTHERS as unique case alternative is not allowed", N
);
1276 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1277 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1280 -- If all our exits were blocked by unconditional transfers of control,
1281 -- then the entire CASE statement acts as an unconditional transfer of
1282 -- control, so treat it like one, and check unreachable code. Skip this
1283 -- test if we had serious errors preventing any statement analysis.
1285 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1286 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1287 Check_Unreachable_Code
(N
);
1289 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1292 -- If the expander is active it will detect the case of a statically
1293 -- determined single alternative and remove warnings for the case, but
1294 -- if we are not doing expansion, that circuit won't be active. Here we
1295 -- duplicate the effect of removing warnings in the same way, so that
1296 -- we will get the same set of warnings in -gnatc mode.
1298 if not Expander_Active
1299 and then Compile_Time_Known_Value
(Expression
(N
))
1300 and then Serious_Errors_Detected
= 0
1303 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1307 Alt
:= First
(Alternatives
(N
));
1308 while Present
(Alt
) loop
1309 if Alt
/= Chosen
then
1310 Remove_Warning_Messages
(Statements
(Alt
));
1317 end Analyze_Case_Statement
;
1319 ----------------------------
1320 -- Analyze_Exit_Statement --
1321 ----------------------------
1323 -- If the exit includes a name, it must be the name of a currently open
1324 -- loop. Otherwise there must be an innermost open loop on the stack, to
1325 -- which the statement implicitly refers.
1327 -- Additionally, in SPARK mode:
1329 -- The exit can only name the closest enclosing loop;
1331 -- An exit with a when clause must be directly contained in a loop;
1333 -- An exit without a when clause must be directly contained in an
1334 -- if-statement with no elsif or else, which is itself directly contained
1335 -- in a loop. The exit must be the last statement in the if-statement.
1337 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1338 Target
: constant Node_Id
:= Name
(N
);
1339 Cond
: constant Node_Id
:= Condition
(N
);
1340 Scope_Id
: Entity_Id
;
1346 Check_Unreachable_Code
(N
);
1349 if Present
(Target
) then
1351 U_Name
:= Entity
(Target
);
1353 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1354 Error_Msg_N
("invalid loop name in exit statement", N
);
1358 if Has_Loop_In_Inner_Open_Scopes
(U_Name
) then
1359 Check_SPARK_05_Restriction
1360 ("exit label must name the closest enclosing loop", N
);
1363 Set_Has_Exit
(U_Name
);
1370 for J
in reverse 0 .. Scope_Stack
.Last
loop
1371 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1372 Kind
:= Ekind
(Scope_Id
);
1374 if Kind
= E_Loop
and then (No
(Target
) or else Scope_Id
= U_Name
) then
1375 Set_Has_Exit
(Scope_Id
);
1378 elsif Kind
= E_Block
1379 or else Kind
= E_Loop
1380 or else Kind
= E_Return_Statement
1386 ("cannot exit from program unit or accept statement", N
);
1391 -- Verify that if present the condition is a Boolean expression
1393 if Present
(Cond
) then
1394 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1395 Check_Unset_Reference
(Cond
);
1398 -- In SPARK mode, verify that the exit statement respects the SPARK
1401 if Present
(Cond
) then
1402 if Nkind
(Parent
(N
)) /= N_Loop_Statement
then
1403 Check_SPARK_05_Restriction
1404 ("exit with when clause must be directly in loop", N
);
1408 if Nkind
(Parent
(N
)) /= N_If_Statement
then
1409 if Nkind
(Parent
(N
)) = N_Elsif_Part
then
1410 Check_SPARK_05_Restriction
1411 ("exit must be in IF without ELSIF", N
);
1413 Check_SPARK_05_Restriction
("exit must be directly in IF", N
);
1416 elsif Nkind
(Parent
(Parent
(N
))) /= N_Loop_Statement
then
1417 Check_SPARK_05_Restriction
1418 ("exit must be in IF directly in loop", N
);
1420 -- First test the presence of ELSE, so that an exit in an ELSE leads
1421 -- to an error mentioning the ELSE.
1423 elsif Present
(Else_Statements
(Parent
(N
))) then
1424 Check_SPARK_05_Restriction
("exit must be in IF without ELSE", N
);
1426 -- An exit in an ELSIF does not reach here, as it would have been
1427 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1429 elsif Present
(Elsif_Parts
(Parent
(N
))) then
1430 Check_SPARK_05_Restriction
("exit must be in IF without ELSIF", N
);
1434 -- Chain exit statement to associated loop entity
1436 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1437 Set_First_Exit_Statement
(Scope_Id
, N
);
1439 -- Since the exit may take us out of a loop, any previous assignment
1440 -- statement is not useless, so clear last assignment indications. It
1441 -- is OK to keep other current values, since if the exit statement
1442 -- does not exit, then the current values are still valid.
1444 Kill_Current_Values
(Last_Assignment_Only
=> True);
1445 end Analyze_Exit_Statement
;
1447 ----------------------------
1448 -- Analyze_Goto_Statement --
1449 ----------------------------
1451 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1452 Label
: constant Node_Id
:= Name
(N
);
1453 Scope_Id
: Entity_Id
;
1454 Label_Scope
: Entity_Id
;
1455 Label_Ent
: Entity_Id
;
1458 Check_SPARK_05_Restriction
("goto statement is not allowed", N
);
1460 -- Actual semantic checks
1462 Check_Unreachable_Code
(N
);
1463 Kill_Current_Values
(Last_Assignment_Only
=> True);
1466 Label_Ent
:= Entity
(Label
);
1468 -- Ignore previous error
1470 if Label_Ent
= Any_Id
then
1471 Check_Error_Detected
;
1474 -- We just have a label as the target of a goto
1476 elsif Ekind
(Label_Ent
) /= E_Label
then
1477 Error_Msg_N
("target of goto statement must be a label", Label
);
1480 -- Check that the target of the goto is reachable according to Ada
1481 -- scoping rules. Note: the special gotos we generate for optimizing
1482 -- local handling of exceptions would violate these rules, but we mark
1483 -- such gotos as analyzed when built, so this code is never entered.
1485 elsif not Reachable
(Label_Ent
) then
1486 Error_Msg_N
("target of goto statement is not reachable", Label
);
1490 -- Here if goto passes initial validity checks
1492 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1494 for J
in reverse 0 .. Scope_Stack
.Last
loop
1495 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1497 if Label_Scope
= Scope_Id
1498 or else not Ekind_In
(Scope_Id
, E_Block
, E_Loop
, E_Return_Statement
)
1500 if Scope_Id
/= Label_Scope
then
1502 ("cannot exit from program unit or accept statement", N
);
1509 raise Program_Error
;
1510 end Analyze_Goto_Statement
;
1512 --------------------------
1513 -- Analyze_If_Statement --
1514 --------------------------
1516 -- A special complication arises in the analysis of if statements
1518 -- The expander has circuitry to completely delete code that it can tell
1519 -- will not be executed (as a result of compile time known conditions). In
1520 -- the analyzer, we ensure that code that will be deleted in this manner
1521 -- is analyzed but not expanded. This is obviously more efficient, but
1522 -- more significantly, difficulties arise if code is expanded and then
1523 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1524 -- generated in deleted code must be frozen from start, because the nodes
1525 -- on which they depend will not be available at the freeze point.
1527 procedure Analyze_If_Statement
(N
: Node_Id
) is
1530 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1531 -- Recursively save value of this global, will be restored on exit
1533 Save_In_Deleted_Code
: Boolean;
1535 Del
: Boolean := False;
1536 -- This flag gets set True if a True condition has been found, which
1537 -- means that remaining ELSE/ELSIF parts are deleted.
1539 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1540 -- This is applied to either the N_If_Statement node itself or to an
1541 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1542 -- statements associated with it.
1544 -----------------------
1545 -- Analyze_Cond_Then --
1546 -----------------------
1548 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1549 Cond
: constant Node_Id
:= Condition
(Cnode
);
1550 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1553 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1554 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1555 Check_Unset_Reference
(Cond
);
1556 Set_Current_Value_Condition
(Cnode
);
1558 -- If already deleting, then just analyze then statements
1561 Analyze_Statements
(Tstm
);
1563 -- Compile time known value, not deleting yet
1565 elsif Compile_Time_Known_Value
(Cond
) then
1566 Save_In_Deleted_Code
:= In_Deleted_Code
;
1568 -- If condition is True, then analyze the THEN statements and set
1569 -- no expansion for ELSE and ELSIF parts.
1571 if Is_True
(Expr_Value
(Cond
)) then
1572 Analyze_Statements
(Tstm
);
1574 Expander_Mode_Save_And_Set
(False);
1575 In_Deleted_Code
:= True;
1577 -- If condition is False, analyze THEN with expansion off
1579 else -- Is_False (Expr_Value (Cond))
1580 Expander_Mode_Save_And_Set
(False);
1581 In_Deleted_Code
:= True;
1582 Analyze_Statements
(Tstm
);
1583 Expander_Mode_Restore
;
1584 In_Deleted_Code
:= Save_In_Deleted_Code
;
1587 -- Not known at compile time, not deleting, normal analysis
1590 Analyze_Statements
(Tstm
);
1592 end Analyze_Cond_Then
;
1594 -- Start of processing for Analyze_If_Statement
1597 -- Initialize exit count for else statements. If there is no else part,
1598 -- this count will stay non-zero reflecting the fact that the uncovered
1599 -- else case is an unblocked exit.
1601 Unblocked_Exit_Count
:= 1;
1602 Analyze_Cond_Then
(N
);
1604 -- Now to analyze the elsif parts if any are present
1606 if Present
(Elsif_Parts
(N
)) then
1607 E
:= First
(Elsif_Parts
(N
));
1608 while Present
(E
) loop
1609 Analyze_Cond_Then
(E
);
1614 if Present
(Else_Statements
(N
)) then
1615 Analyze_Statements
(Else_Statements
(N
));
1618 -- If all our exits were blocked by unconditional transfers of control,
1619 -- then the entire IF statement acts as an unconditional transfer of
1620 -- control, so treat it like one, and check unreachable code.
1622 if Unblocked_Exit_Count
= 0 then
1623 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1624 Check_Unreachable_Code
(N
);
1626 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1630 Expander_Mode_Restore
;
1631 In_Deleted_Code
:= Save_In_Deleted_Code
;
1634 if not Expander_Active
1635 and then Compile_Time_Known_Value
(Condition
(N
))
1636 and then Serious_Errors_Detected
= 0
1638 if Is_True
(Expr_Value
(Condition
(N
))) then
1639 Remove_Warning_Messages
(Else_Statements
(N
));
1641 if Present
(Elsif_Parts
(N
)) then
1642 E
:= First
(Elsif_Parts
(N
));
1643 while Present
(E
) loop
1644 Remove_Warning_Messages
(Then_Statements
(E
));
1650 Remove_Warning_Messages
(Then_Statements
(N
));
1654 -- Warn on redundant if statement that has no effect
1656 -- Note, we could also check empty ELSIF parts ???
1658 if Warn_On_Redundant_Constructs
1660 -- If statement must be from source
1662 and then Comes_From_Source
(N
)
1664 -- Condition must not have obvious side effect
1666 and then Has_No_Obvious_Side_Effects
(Condition
(N
))
1668 -- No elsif parts of else part
1670 and then No
(Elsif_Parts
(N
))
1671 and then No
(Else_Statements
(N
))
1673 -- Then must be a single null statement
1675 and then List_Length
(Then_Statements
(N
)) = 1
1677 -- Go to original node, since we may have rewritten something as
1678 -- a null statement (e.g. a case we could figure the outcome of).
1681 T
: constant Node_Id
:= First
(Then_Statements
(N
));
1682 S
: constant Node_Id
:= Original_Node
(T
);
1685 if Comes_From_Source
(S
) and then Nkind
(S
) = N_Null_Statement
then
1686 Error_Msg_N
("if statement has no effect?r?", N
);
1690 end Analyze_If_Statement
;
1692 ----------------------------------------
1693 -- Analyze_Implicit_Label_Declaration --
1694 ----------------------------------------
1696 -- An implicit label declaration is generated in the innermost enclosing
1697 -- declarative part. This is done for labels, and block and loop names.
1699 -- Note: any changes in this routine may need to be reflected in
1700 -- Analyze_Label_Entity.
1702 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
1703 Id
: constant Node_Id
:= Defining_Identifier
(N
);
1706 Set_Ekind
(Id
, E_Label
);
1707 Set_Etype
(Id
, Standard_Void_Type
);
1708 Set_Enclosing_Scope
(Id
, Current_Scope
);
1709 end Analyze_Implicit_Label_Declaration
;
1711 ------------------------------
1712 -- Analyze_Iteration_Scheme --
1713 ------------------------------
1715 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
1717 Iter_Spec
: Node_Id
;
1718 Loop_Spec
: Node_Id
;
1721 -- For an infinite loop, there is no iteration scheme
1727 Cond
:= Condition
(N
);
1728 Iter_Spec
:= Iterator_Specification
(N
);
1729 Loop_Spec
:= Loop_Parameter_Specification
(N
);
1731 if Present
(Cond
) then
1732 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1733 Check_Unset_Reference
(Cond
);
1734 Set_Current_Value_Condition
(N
);
1736 elsif Present
(Iter_Spec
) then
1737 Analyze_Iterator_Specification
(Iter_Spec
);
1740 Analyze_Loop_Parameter_Specification
(Loop_Spec
);
1742 end Analyze_Iteration_Scheme
;
1744 ------------------------------------
1745 -- Analyze_Iterator_Specification --
1746 ------------------------------------
1748 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
1749 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
);
1750 -- For an iteration over a container, if the loop carries the Reverse
1751 -- indicator, verify that the container type has an Iterate aspect that
1752 -- implements the reversible iterator interface.
1754 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
;
1755 -- For containers with Iterator and related aspects, the cursor is
1756 -- obtained by locating an entity with the proper name in the scope
1759 -----------------------------
1760 -- Check_Reverse_Iteration --
1761 -----------------------------
1763 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
) is
1765 if Reverse_Present
(N
)
1766 and then not Is_Array_Type
(Typ
)
1767 and then not Is_Reversible_Iterator
(Typ
)
1770 ("container type does not support reverse iteration", N
, Typ
);
1772 end Check_Reverse_Iteration
;
1774 ---------------------
1775 -- Get_Cursor_Type --
1776 ---------------------
1778 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
is
1782 -- If iterator type is derived, the cursor is declared in the scope
1783 -- of the parent type.
1785 if Is_Derived_Type
(Typ
) then
1786 Ent
:= First_Entity
(Scope
(Etype
(Typ
)));
1788 Ent
:= First_Entity
(Scope
(Typ
));
1791 while Present
(Ent
) loop
1792 exit when Chars
(Ent
) = Name_Cursor
;
1800 -- The cursor is the target of generated assignments in the
1801 -- loop, and cannot have a limited type.
1803 if Is_Limited_Type
(Etype
(Ent
)) then
1804 Error_Msg_N
("cursor type cannot be limited", N
);
1808 end Get_Cursor_Type
;
1812 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
1813 Iter_Name
: constant Node_Id
:= Name
(N
);
1814 Loc
: constant Source_Ptr
:= Sloc
(N
);
1815 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
1820 -- Start of processing for Analyze_Iterator_Specification
1823 Enter_Name
(Def_Id
);
1825 -- AI12-0151 specifies that when the subtype indication is present, it
1826 -- must statically match the type of the array or container element.
1827 -- To simplify this check, we introduce a subtype declaration with the
1828 -- given subtype indication when it carries a constraint, and rewrite
1829 -- the original as a reference to the created subtype entity.
1831 if Present
(Subt
) then
1832 if Nkind
(Subt
) = N_Subtype_Indication
then
1834 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
1835 Decl
: constant Node_Id
:=
1836 Make_Subtype_Declaration
(Loc
,
1837 Defining_Identifier
=> S
,
1838 Subtype_Indication
=> New_Copy_Tree
(Subt
));
1840 Insert_Before
(Parent
(Parent
(N
)), Decl
);
1842 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
1848 -- Save entity of subtype indication for subsequent check
1850 Bas
:= Entity
(Subt
);
1853 Preanalyze_Range
(Iter_Name
);
1855 -- Set the kind of the loop variable, which is not visible within
1856 -- the iterator name.
1858 Set_Ekind
(Def_Id
, E_Variable
);
1860 -- Provide a link between the iterator variable and the container, for
1861 -- subsequent use in cross-reference and modification information.
1863 if Of_Present
(N
) then
1864 Set_Related_Expression
(Def_Id
, Iter_Name
);
1866 -- For a container, the iterator is specified through the aspect
1868 if not Is_Array_Type
(Etype
(Iter_Name
)) then
1870 Iterator
: constant Entity_Id
:=
1871 Find_Value_Of_Aspect
1872 (Etype
(Iter_Name
), Aspect_Default_Iterator
);
1878 if No
(Iterator
) then
1879 null; -- error reported below.
1881 elsif not Is_Overloaded
(Iterator
) then
1882 Check_Reverse_Iteration
(Etype
(Iterator
));
1884 -- If Iterator is overloaded, use reversible iterator if
1885 -- one is available.
1887 elsif Is_Overloaded
(Iterator
) then
1888 Get_First_Interp
(Iterator
, I
, It
);
1889 while Present
(It
.Nam
) loop
1890 if Ekind
(It
.Nam
) = E_Function
1891 and then Is_Reversible_Iterator
(Etype
(It
.Nam
))
1893 Set_Etype
(Iterator
, It
.Typ
);
1894 Set_Entity
(Iterator
, It
.Nam
);
1898 Get_Next_Interp
(I
, It
);
1901 Check_Reverse_Iteration
(Etype
(Iterator
));
1907 -- If the domain of iteration is an expression, create a declaration for
1908 -- it, so that finalization actions are introduced outside of the loop.
1909 -- The declaration must be a renaming because the body of the loop may
1910 -- assign to elements.
1912 if not Is_Entity_Name
(Iter_Name
)
1914 -- When the context is a quantified expression, the renaming
1915 -- declaration is delayed until the expansion phase if we are
1918 and then (Nkind
(Parent
(N
)) /= N_Quantified_Expression
1919 or else Operating_Mode
= Check_Semantics
)
1921 -- Do not perform this expansion in SPARK mode, since the formal
1922 -- verification directly deals with the source form of the iterator.
1923 -- Ditto for ASIS and when expansion is disabled, where the temporary
1924 -- may hide the transformation of a selected component into a prefixed
1925 -- function call, and references need to see the original expression.
1927 and then not GNATprove_Mode
1928 and then Expander_Active
1931 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
1937 -- If the domain of iteration is an array component that depends
1938 -- on a discriminant, create actual subtype for it. Pre-analysis
1939 -- does not generate the actual subtype of a selected component.
1941 if Nkind
(Iter_Name
) = N_Selected_Component
1942 and then Is_Array_Type
(Etype
(Iter_Name
))
1945 Build_Actual_Subtype_Of_Component
1946 (Etype
(Selector_Name
(Iter_Name
)), Iter_Name
);
1947 Insert_Action
(N
, Act_S
);
1949 if Present
(Act_S
) then
1950 Typ
:= Defining_Identifier
(Act_S
);
1952 Typ
:= Etype
(Iter_Name
);
1956 Typ
:= Etype
(Iter_Name
);
1958 -- Verify that the expression produces an iterator
1960 if not Of_Present
(N
) and then not Is_Iterator
(Typ
)
1961 and then not Is_Array_Type
(Typ
)
1962 and then No
(Find_Aspect
(Typ
, Aspect_Iterable
))
1965 ("expect object that implements iterator interface",
1970 -- Protect against malformed iterator
1972 if Typ
= Any_Type
then
1973 Error_Msg_N
("invalid expression in loop iterator", Iter_Name
);
1977 if not Of_Present
(N
) then
1978 Check_Reverse_Iteration
(Typ
);
1981 -- The name in the renaming declaration may be a function call.
1982 -- Indicate that it does not come from source, to suppress
1983 -- spurious warnings on renamings of parameterless functions,
1984 -- a common enough idiom in user-defined iterators.
1987 Make_Object_Renaming_Declaration
(Loc
,
1988 Defining_Identifier
=> Id
,
1989 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
1991 New_Copy_Tree
(Iter_Name
, New_Sloc
=> Loc
));
1993 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
1994 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
1995 Set_Etype
(Id
, Typ
);
1996 Set_Etype
(Name
(N
), Typ
);
1999 -- Container is an entity or an array with uncontrolled components, or
2000 -- else it is a container iterator given by a function call, typically
2001 -- called Iterate in the case of predefined containers, even though
2002 -- Iterate is not a reserved name. What matters is that the return type
2003 -- of the function is an iterator type.
2005 elsif Is_Entity_Name
(Iter_Name
) then
2006 Analyze
(Iter_Name
);
2008 if Nkind
(Iter_Name
) = N_Function_Call
then
2010 C
: constant Node_Id
:= Name
(Iter_Name
);
2015 if not Is_Overloaded
(Iter_Name
) then
2016 Resolve
(Iter_Name
, Etype
(C
));
2019 Get_First_Interp
(C
, I
, It
);
2020 while It
.Typ
/= Empty
loop
2021 if Reverse_Present
(N
) then
2022 if Is_Reversible_Iterator
(It
.Typ
) then
2023 Resolve
(Iter_Name
, It
.Typ
);
2027 elsif Is_Iterator
(It
.Typ
) then
2028 Resolve
(Iter_Name
, It
.Typ
);
2032 Get_Next_Interp
(I
, It
);
2037 -- Domain of iteration is not overloaded
2040 Resolve
(Iter_Name
, Etype
(Iter_Name
));
2043 if not Of_Present
(N
) then
2044 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2048 -- Get base type of container, for proper retrieval of Cursor type
2049 -- and primitive operations.
2051 Typ
:= Base_Type
(Etype
(Iter_Name
));
2053 if Is_Array_Type
(Typ
) then
2054 if Of_Present
(N
) then
2055 Set_Etype
(Def_Id
, Component_Type
(Typ
));
2057 -- The loop variable is aliased if the array components are
2060 Set_Is_Aliased
(Def_Id
, Has_Aliased_Components
(Typ
));
2062 -- AI12-0047 stipulates that the domain (array or container)
2063 -- cannot be a component that depends on a discriminant if the
2064 -- enclosing object is mutable, to prevent a modification of the
2065 -- dowmain of iteration in the course of an iteration.
2067 -- If the object is an expression it has been captured in a
2068 -- temporary, so examine original node.
2070 if Nkind
(Original_Node
(Iter_Name
)) = N_Selected_Component
2071 and then Is_Dependent_Component_Of_Mutable_Object
2072 (Original_Node
(Iter_Name
))
2075 ("iterable name cannot be a discriminant-dependent "
2076 & "component of a mutable object", N
);
2081 (Base_Type
(Bas
) /= Base_Type
(Component_Type
(Typ
))
2083 not Subtypes_Statically_Match
(Bas
, Component_Type
(Typ
)))
2086 ("subtype indication does not match component type", Subt
);
2089 -- Here we have a missing Range attribute
2093 ("missing Range attribute in iteration over an array", N
);
2095 -- In Ada 2012 mode, this may be an attempt at an iterator
2097 if Ada_Version
>= Ada_2012
then
2099 ("\if& is meant to designate an element of the array, use OF",
2103 -- Prevent cascaded errors
2105 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2106 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2109 -- Check for type error in iterator
2111 elsif Typ
= Any_Type
then
2114 -- Iteration over a container
2117 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2118 Error_Msg_Ada_2012_Feature
("container iterator", Sloc
(N
));
2122 if Of_Present
(N
) then
2123 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2125 Elt
: constant Entity_Id
:=
2126 Get_Iterable_Type_Primitive
(Typ
, Name_Element
);
2130 ("missing Element primitive for iteration", N
);
2132 Set_Etype
(Def_Id
, Etype
(Elt
));
2136 -- For a predefined container, The type of the loop variable is
2137 -- the Iterator_Element aspect of the container type.
2141 Element
: constant Entity_Id
:=
2142 Find_Value_Of_Aspect
2143 (Typ
, Aspect_Iterator_Element
);
2144 Iterator
: constant Entity_Id
:=
2145 Find_Value_Of_Aspect
2146 (Typ
, Aspect_Default_Iterator
);
2147 Orig_Iter_Name
: constant Node_Id
:=
2148 Original_Node
(Iter_Name
);
2149 Cursor_Type
: Entity_Id
;
2152 if No
(Element
) then
2153 Error_Msg_NE
("cannot iterate over&", N
, Typ
);
2157 Set_Etype
(Def_Id
, Entity
(Element
));
2158 Cursor_Type
:= Get_Cursor_Type
(Typ
);
2159 pragma Assert
(Present
(Cursor_Type
));
2161 -- If subtype indication was given, verify that it covers
2162 -- the element type of the container.
2165 and then (not Covers
(Bas
, Etype
(Def_Id
))
2166 or else not Subtypes_Statically_Match
2167 (Bas
, Etype
(Def_Id
)))
2170 ("subtype indication does not match element type",
2174 -- If the container has a variable indexing aspect, the
2175 -- element is a variable and is modifiable in the loop.
2177 if Has_Aspect
(Typ
, Aspect_Variable_Indexing
) then
2178 Set_Ekind
(Def_Id
, E_Variable
);
2181 -- If the container is a constant, iterating over it
2182 -- requires a Constant_Indexing operation.
2184 if not Is_Variable
(Iter_Name
)
2185 and then not Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
2188 ("iteration over constant container require "
2189 & "constant_indexing aspect", N
);
2191 -- The Iterate function may have an in_out parameter,
2192 -- and a constant container is thus illegal.
2194 elsif Present
(Iterator
)
2195 and then Ekind
(Entity
(Iterator
)) = E_Function
2196 and then Ekind
(First_Formal
(Entity
(Iterator
))) /=
2198 and then not Is_Variable
(Iter_Name
)
2200 Error_Msg_N
("variable container expected", N
);
2203 -- Detect a case where the iterator denotes a component
2204 -- of a mutable object which depends on a discriminant.
2205 -- Note that the iterator may denote a function call in
2206 -- qualified form, in which case this check should not
2209 if Nkind
(Orig_Iter_Name
) = N_Selected_Component
2211 Present
(Entity
(Selector_Name
(Orig_Iter_Name
)))
2213 (Entity
(Selector_Name
(Orig_Iter_Name
)),
2216 and then Is_Dependent_Component_Of_Mutable_Object
2220 ("container cannot be a discriminant-dependent "
2221 & "component of a mutable object", N
);
2227 -- IN iterator, domain is a range, or a call to Iterate function
2230 -- For an iteration of the form IN, the name must denote an
2231 -- iterator, typically the result of a call to Iterate. Give a
2232 -- useful error message when the name is a container by itself.
2234 -- The type may be a formal container type, which has to have
2235 -- an Iterable aspect detailing the required primitives.
2237 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2238 and then not Is_Iterator
(Typ
)
2240 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2243 elsif not Has_Aspect
(Typ
, Aspect_Iterator_Element
) then
2245 ("cannot iterate over&", Name
(N
), Typ
);
2248 ("name must be an iterator, not a container", Name
(N
));
2251 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2255 ("\to iterate directly over the elements of a container, "
2256 & "write `of &`", Name
(N
), Original_Node
(Name
(N
)));
2258 -- No point in continuing analysis of iterator spec
2264 -- If the name is a call (typically prefixed) to some Iterate
2265 -- function, it has been rewritten as an object declaration.
2266 -- If that object is a selected component, verify that it is not
2267 -- a component of an unconstrained mutable object.
2269 if Nkind
(Iter_Name
) = N_Identifier
2270 or else (not Expander_Active
and Comes_From_Source
(Iter_Name
))
2273 Orig_Node
: constant Node_Id
:= Original_Node
(Iter_Name
);
2274 Iter_Kind
: constant Node_Kind
:= Nkind
(Orig_Node
);
2278 if Iter_Kind
= N_Selected_Component
then
2279 Obj
:= Prefix
(Orig_Node
);
2281 elsif Iter_Kind
= N_Function_Call
then
2282 Obj
:= First_Actual
(Orig_Node
);
2284 -- If neither, the name comes from source
2290 if Nkind
(Obj
) = N_Selected_Component
2291 and then Is_Dependent_Component_Of_Mutable_Object
(Obj
)
2294 ("container cannot be a discriminant-dependent "
2295 & "component of a mutable object", N
);
2300 -- The result type of Iterate function is the classwide type of
2301 -- the interface parent. We need the specific Cursor type defined
2302 -- in the container package. We obtain it by name for a predefined
2303 -- container, or through the Iterable aspect for a formal one.
2305 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2308 (Parent
(Find_Value_Of_Aspect
(Typ
, Aspect_Iterable
)),
2312 Set_Etype
(Def_Id
, Get_Cursor_Type
(Typ
));
2313 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2318 end Analyze_Iterator_Specification
;
2324 -- Note: the semantic work required for analyzing labels (setting them as
2325 -- reachable) was done in a prepass through the statements in the block,
2326 -- so that forward gotos would be properly handled. See Analyze_Statements
2327 -- for further details. The only processing required here is to deal with
2328 -- optimizations that depend on an assumption of sequential control flow,
2329 -- since of course the occurrence of a label breaks this assumption.
2331 procedure Analyze_Label
(N
: Node_Id
) is
2332 pragma Warnings
(Off
, N
);
2334 Kill_Current_Values
;
2337 --------------------------
2338 -- Analyze_Label_Entity --
2339 --------------------------
2341 procedure Analyze_Label_Entity
(E
: Entity_Id
) is
2343 Set_Ekind
(E
, E_Label
);
2344 Set_Etype
(E
, Standard_Void_Type
);
2345 Set_Enclosing_Scope
(E
, Current_Scope
);
2346 Set_Reachable
(E
, True);
2347 end Analyze_Label_Entity
;
2349 ------------------------------------------
2350 -- Analyze_Loop_Parameter_Specification --
2351 ------------------------------------------
2353 procedure Analyze_Loop_Parameter_Specification
(N
: Node_Id
) is
2354 Loop_Nod
: constant Node_Id
:= Parent
(Parent
(N
));
2356 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
2357 -- If the bounds are given by a 'Range reference on a function call
2358 -- that returns a controlled array, introduce an explicit declaration
2359 -- to capture the bounds, so that the function result can be finalized
2360 -- in timely fashion.
2362 procedure Check_Predicate_Use
(T
: Entity_Id
);
2363 -- Diagnose Attempt to iterate through non-static predicate. Note that
2364 -- a type with inherited predicates may have both static and dynamic
2365 -- forms. In this case it is not sufficent to check the static predicate
2366 -- function only, look for a dynamic predicate aspect as well.
2368 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean;
2369 -- N is the node for an arbitrary construct. This function searches the
2370 -- construct N to see if any expressions within it contain function
2371 -- calls that use the secondary stack, returning True if any such call
2372 -- is found, and False otherwise.
2374 procedure Process_Bounds
(R
: Node_Id
);
2375 -- If the iteration is given by a range, create temporaries and
2376 -- assignment statements block to capture the bounds and perform
2377 -- required finalization actions in case a bound includes a function
2378 -- call that uses the temporary stack. We first pre-analyze a copy of
2379 -- the range in order to determine the expected type, and analyze and
2380 -- resolve the original bounds.
2382 --------------------------------------
2383 -- Check_Controlled_Array_Attribute --
2384 --------------------------------------
2386 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
2388 if Nkind
(DS
) = N_Attribute_Reference
2389 and then Is_Entity_Name
(Prefix
(DS
))
2390 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
2391 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
2393 Is_Controlled
(Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
2394 and then Expander_Active
2397 Loc
: constant Source_Ptr
:= Sloc
(N
);
2398 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
2399 Indx
: constant Entity_Id
:=
2400 Base_Type
(Etype
(First_Index
(Arr
)));
2401 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
2406 Make_Subtype_Declaration
(Loc
,
2407 Defining_Identifier
=> Subt
,
2408 Subtype_Indication
=>
2409 Make_Subtype_Indication
(Loc
,
2410 Subtype_Mark
=> New_Occurrence_Of
(Indx
, Loc
),
2412 Make_Range_Constraint
(Loc
, Relocate_Node
(DS
))));
2413 Insert_Before
(Loop_Nod
, Decl
);
2417 Make_Attribute_Reference
(Loc
,
2418 Prefix
=> New_Occurrence_Of
(Subt
, Loc
),
2419 Attribute_Name
=> Attribute_Name
(DS
)));
2424 end Check_Controlled_Array_Attribute
;
2426 -------------------------
2427 -- Check_Predicate_Use --
2428 -------------------------
2430 procedure Check_Predicate_Use
(T
: Entity_Id
) is
2432 -- A predicated subtype is illegal in loops and related constructs
2433 -- if the predicate is not static, or if it is a non-static subtype
2434 -- of a statically predicated subtype.
2436 if Is_Discrete_Type
(T
)
2437 and then Has_Predicates
(T
)
2438 and then (not Has_Static_Predicate
(T
)
2439 or else not Is_Static_Subtype
(T
)
2440 or else Has_Dynamic_Predicate_Aspect
(T
))
2442 -- Seems a confusing message for the case of a static predicate
2443 -- with a non-static subtype???
2445 Bad_Predicated_Subtype_Use
2446 ("cannot use subtype& with non-static predicate for loop "
2447 & "iteration", Discrete_Subtype_Definition
(N
),
2448 T
, Suggest_Static
=> True);
2450 elsif Inside_A_Generic
and then Is_Generic_Formal
(T
) then
2451 Set_No_Dynamic_Predicate_On_Actual
(T
);
2453 end Check_Predicate_Use
;
2455 ------------------------------------
2456 -- Has_Call_Using_Secondary_Stack --
2457 ------------------------------------
2459 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean is
2461 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
2462 -- Check if N is a function call which uses the secondary stack
2468 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
2471 Return_Typ
: Entity_Id
;
2474 if Nkind
(N
) = N_Function_Call
then
2477 -- Call using access to subprogram with explicit dereference
2479 if Nkind
(Nam
) = N_Explicit_Dereference
then
2480 Subp
:= Etype
(Nam
);
2482 -- Call using a selected component notation or Ada 2005 object
2483 -- operation notation
2485 elsif Nkind
(Nam
) = N_Selected_Component
then
2486 Subp
:= Entity
(Selector_Name
(Nam
));
2491 Subp
:= Entity
(Nam
);
2494 Return_Typ
:= Etype
(Subp
);
2496 if Is_Composite_Type
(Return_Typ
)
2497 and then not Is_Constrained
(Return_Typ
)
2501 elsif Sec_Stack_Needed_For_Return
(Subp
) then
2506 -- Continue traversing the tree
2511 function Check_Calls
is new Traverse_Func
(Check_Call
);
2513 -- Start of processing for Has_Call_Using_Secondary_Stack
2516 return Check_Calls
(N
) = Abandon
;
2517 end Has_Call_Using_Secondary_Stack
;
2519 --------------------
2520 -- Process_Bounds --
2521 --------------------
2523 procedure Process_Bounds
(R
: Node_Id
) is
2524 Loc
: constant Source_Ptr
:= Sloc
(N
);
2527 (Original_Bound
: Node_Id
;
2528 Analyzed_Bound
: Node_Id
;
2529 Typ
: Entity_Id
) return Node_Id
;
2530 -- Capture value of bound and return captured value
2537 (Original_Bound
: Node_Id
;
2538 Analyzed_Bound
: Node_Id
;
2539 Typ
: Entity_Id
) return Node_Id
2546 -- If the bound is a constant or an object, no need for a separate
2547 -- declaration. If the bound is the result of previous expansion
2548 -- it is already analyzed and should not be modified. Note that
2549 -- the Bound will be resolved later, if needed, as part of the
2550 -- call to Make_Index (literal bounds may need to be resolved to
2553 if Analyzed
(Original_Bound
) then
2554 return Original_Bound
;
2556 elsif Nkind_In
(Analyzed_Bound
, N_Integer_Literal
,
2557 N_Character_Literal
)
2558 or else Is_Entity_Name
(Analyzed_Bound
)
2560 Analyze_And_Resolve
(Original_Bound
, Typ
);
2561 return Original_Bound
;
2564 -- Normally, the best approach is simply to generate a constant
2565 -- declaration that captures the bound. However, there is a nasty
2566 -- case where this is wrong. If the bound is complex, and has a
2567 -- possible use of the secondary stack, we need to generate a
2568 -- separate assignment statement to ensure the creation of a block
2569 -- which will release the secondary stack.
2571 -- We prefer the constant declaration, since it leaves us with a
2572 -- proper trace of the value, useful in optimizations that get rid
2573 -- of junk range checks.
2575 if not Has_Call_Using_Secondary_Stack
(Analyzed_Bound
) then
2576 Analyze_And_Resolve
(Original_Bound
, Typ
);
2578 -- Ensure that the bound is valid. This check should not be
2579 -- generated when the range belongs to a quantified expression
2580 -- as the construct is still not expanded into its final form.
2582 if Nkind
(Parent
(R
)) /= N_Loop_Parameter_Specification
2583 or else Nkind
(Parent
(Parent
(R
))) /= N_Quantified_Expression
2585 Ensure_Valid
(Original_Bound
);
2588 Force_Evaluation
(Original_Bound
);
2589 return Original_Bound
;
2592 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
2594 -- Here we make a declaration with a separate assignment
2595 -- statement, and insert before loop header.
2598 Make_Object_Declaration
(Loc
,
2599 Defining_Identifier
=> Id
,
2600 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
2603 Make_Assignment_Statement
(Loc
,
2604 Name
=> New_Occurrence_Of
(Id
, Loc
),
2605 Expression
=> Relocate_Node
(Original_Bound
));
2607 Insert_Actions
(Loop_Nod
, New_List
(Decl
, Assign
));
2609 -- Now that this temporary variable is initialized we decorate it
2610 -- as safe-to-reevaluate to inform to the backend that no further
2611 -- asignment will be issued and hence it can be handled as side
2612 -- effect free. Note that this decoration must be done when the
2613 -- assignment has been analyzed because otherwise it will be
2614 -- rejected (see Analyze_Assignment).
2616 Set_Is_Safe_To_Reevaluate
(Id
);
2618 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
2620 if Nkind
(Assign
) = N_Assignment_Statement
then
2621 return Expression
(Assign
);
2623 return Original_Bound
;
2627 Hi
: constant Node_Id
:= High_Bound
(R
);
2628 Lo
: constant Node_Id
:= Low_Bound
(R
);
2629 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
2634 -- Start of processing for Process_Bounds
2637 Set_Parent
(R_Copy
, Parent
(R
));
2638 Preanalyze_Range
(R_Copy
);
2639 Typ
:= Etype
(R_Copy
);
2641 -- If the type of the discrete range is Universal_Integer, then the
2642 -- bound's type must be resolved to Integer, and any object used to
2643 -- hold the bound must also have type Integer, unless the literal
2644 -- bounds are constant-folded expressions with a user-defined type.
2646 if Typ
= Universal_Integer
then
2647 if Nkind
(Lo
) = N_Integer_Literal
2648 and then Present
(Etype
(Lo
))
2649 and then Scope
(Etype
(Lo
)) /= Standard_Standard
2653 elsif Nkind
(Hi
) = N_Integer_Literal
2654 and then Present
(Etype
(Hi
))
2655 and then Scope
(Etype
(Hi
)) /= Standard_Standard
2660 Typ
:= Standard_Integer
;
2666 New_Lo
:= One_Bound
(Lo
, Low_Bound
(R_Copy
), Typ
);
2667 New_Hi
:= One_Bound
(Hi
, High_Bound
(R_Copy
), Typ
);
2669 -- Propagate staticness to loop range itself, in case the
2670 -- corresponding subtype is static.
2672 if New_Lo
/= Lo
and then Is_OK_Static_Expression
(New_Lo
) then
2673 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo
));
2676 if New_Hi
/= Hi
and then Is_OK_Static_Expression
(New_Hi
) then
2677 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi
));
2683 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(N
);
2684 Id
: constant Entity_Id
:= Defining_Identifier
(N
);
2688 -- Start of processing for Analyze_Loop_Parameter_Specification
2693 -- We always consider the loop variable to be referenced, since the loop
2694 -- may be used just for counting purposes.
2696 Generate_Reference
(Id
, N
, ' ');
2698 -- Check for the case of loop variable hiding a local variable (used
2699 -- later on to give a nice warning if the hidden variable is never
2703 H
: constant Entity_Id
:= Homonym
(Id
);
2706 and then Ekind
(H
) = E_Variable
2707 and then Is_Discrete_Type
(Etype
(H
))
2708 and then Enclosing_Dynamic_Scope
(H
) = Enclosing_Dynamic_Scope
(Id
)
2710 Set_Hiding_Loop_Variable
(H
, Id
);
2714 -- Loop parameter specification must include subtype mark in SPARK
2716 if Nkind
(DS
) = N_Range
then
2717 Check_SPARK_05_Restriction
2718 ("loop parameter specification must include subtype mark", N
);
2721 -- Analyze the subtype definition and create temporaries for the bounds.
2722 -- Do not evaluate the range when preanalyzing a quantified expression
2723 -- because bounds expressed as function calls with side effects will be
2724 -- incorrectly replicated.
2726 if Nkind
(DS
) = N_Range
2727 and then Expander_Active
2728 and then Nkind
(Parent
(N
)) /= N_Quantified_Expression
2730 Process_Bounds
(DS
);
2732 -- Either the expander not active or the range of iteration is a subtype
2733 -- indication, an entity, or a function call that yields an aggregate or
2737 DS_Copy
:= New_Copy_Tree
(DS
);
2738 Set_Parent
(DS_Copy
, Parent
(DS
));
2739 Preanalyze_Range
(DS_Copy
);
2741 -- Ada 2012: If the domain of iteration is:
2743 -- a) a function call,
2744 -- b) an identifier that is not a type,
2745 -- c) an attribute reference 'Old (within a postcondition),
2746 -- d) an unchecked conversion or a qualified expression with
2747 -- the proper iterator type.
2749 -- then it is an iteration over a container. It was classified as
2750 -- a loop specification by the parser, and must be rewritten now
2751 -- to activate container iteration. The last case will occur within
2752 -- an expanded inlined call, where the expansion wraps an actual in
2753 -- an unchecked conversion when needed. The expression of the
2754 -- conversion is always an object.
2756 if Nkind
(DS_Copy
) = N_Function_Call
2758 or else (Is_Entity_Name
(DS_Copy
)
2759 and then not Is_Type
(Entity
(DS_Copy
)))
2761 or else (Nkind
(DS_Copy
) = N_Attribute_Reference
2762 and then Nam_In
(Attribute_Name
(DS_Copy
),
2763 Name_Loop_Entry
, Name_Old
))
2765 or else Has_Aspect
(Etype
(DS_Copy
), Aspect_Iterable
)
2767 or else Nkind
(DS_Copy
) = N_Unchecked_Type_Conversion
2768 or else (Nkind
(DS_Copy
) = N_Qualified_Expression
2769 and then Is_Iterator
(Etype
(DS_Copy
)))
2771 -- This is an iterator specification. Rewrite it as such and
2772 -- analyze it to capture function calls that may require
2773 -- finalization actions.
2776 I_Spec
: constant Node_Id
:=
2777 Make_Iterator_Specification
(Sloc
(N
),
2778 Defining_Identifier
=> Relocate_Node
(Id
),
2780 Subtype_Indication
=> Empty
,
2781 Reverse_Present
=> Reverse_Present
(N
));
2782 Scheme
: constant Node_Id
:= Parent
(N
);
2785 Set_Iterator_Specification
(Scheme
, I_Spec
);
2786 Set_Loop_Parameter_Specification
(Scheme
, Empty
);
2787 Analyze_Iterator_Specification
(I_Spec
);
2789 -- In a generic context, analyze the original domain of
2790 -- iteration, for name capture.
2792 if not Expander_Active
then
2796 -- Set kind of loop parameter, which may be used in the
2797 -- subsequent analysis of the condition in a quantified
2800 Set_Ekind
(Id
, E_Loop_Parameter
);
2804 -- Domain of iteration is not a function call, and is side-effect
2808 -- A quantified expression that appears in a pre/post condition
2809 -- is pre-analyzed several times. If the range is given by an
2810 -- attribute reference it is rewritten as a range, and this is
2811 -- done even with expansion disabled. If the type is already set
2812 -- do not reanalyze, because a range with static bounds may be
2813 -- typed Integer by default.
2815 if Nkind
(Parent
(N
)) = N_Quantified_Expression
2816 and then Present
(Etype
(DS
))
2829 -- Some additional checks if we are iterating through a type
2831 if Is_Entity_Name
(DS
)
2832 and then Present
(Entity
(DS
))
2833 and then Is_Type
(Entity
(DS
))
2835 -- The subtype indication may denote the completion of an incomplete
2836 -- type declaration.
2838 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
2839 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
2840 Set_Etype
(DS
, Entity
(DS
));
2843 Check_Predicate_Use
(Entity
(DS
));
2846 -- Error if not discrete type
2848 if not Is_Discrete_Type
(Etype
(DS
)) then
2849 Wrong_Type
(DS
, Any_Discrete
);
2850 Set_Etype
(DS
, Any_Type
);
2853 Check_Controlled_Array_Attribute
(DS
);
2855 if Nkind
(DS
) = N_Subtype_Indication
then
2856 Check_Predicate_Use
(Entity
(Subtype_Mark
(DS
)));
2859 Make_Index
(DS
, N
, In_Iter_Schm
=> True);
2860 Set_Ekind
(Id
, E_Loop_Parameter
);
2862 -- A quantified expression which appears in a pre- or post-condition may
2863 -- be analyzed multiple times. The analysis of the range creates several
2864 -- itypes which reside in different scopes depending on whether the pre-
2865 -- or post-condition has been expanded. Update the type of the loop
2866 -- variable to reflect the proper itype at each stage of analysis.
2869 or else Etype
(Id
) = Any_Type
2871 (Present
(Etype
(Id
))
2872 and then Is_Itype
(Etype
(Id
))
2873 and then Nkind
(Parent
(Loop_Nod
)) = N_Expression_With_Actions
2874 and then Nkind
(Original_Node
(Parent
(Loop_Nod
))) =
2875 N_Quantified_Expression
)
2877 Set_Etype
(Id
, Etype
(DS
));
2880 -- Treat a range as an implicit reference to the type, to inhibit
2881 -- spurious warnings.
2883 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
2884 Set_Is_Known_Valid
(Id
, True);
2886 -- The loop is not a declarative part, so the loop variable must be
2887 -- frozen explicitly. Do not freeze while preanalyzing a quantified
2888 -- expression because the freeze node will not be inserted into the
2889 -- tree due to flag Is_Spec_Expression being set.
2891 if Nkind
(Parent
(N
)) /= N_Quantified_Expression
then
2893 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
2895 if Is_Non_Empty_List
(Flist
) then
2896 Insert_Actions
(N
, Flist
);
2901 -- Case where we have a range or a subtype, get type bounds
2903 if Nkind_In
(DS
, N_Range
, N_Subtype_Indication
)
2904 and then not Error_Posted
(DS
)
2905 and then Etype
(DS
) /= Any_Type
2906 and then Is_Discrete_Type
(Etype
(DS
))
2913 if Nkind
(DS
) = N_Range
then
2914 L
:= Low_Bound
(DS
);
2915 H
:= High_Bound
(DS
);
2918 Type_Low_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
2920 Type_High_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
2923 -- Check for null or possibly null range and issue warning. We
2924 -- suppress such messages in generic templates and instances,
2925 -- because in practice they tend to be dubious in these cases. The
2926 -- check applies as well to rewritten array element loops where a
2927 -- null range may be detected statically.
2929 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> True) = GT
then
2931 -- Suppress the warning if inside a generic template or
2932 -- instance, since in practice they tend to be dubious in these
2933 -- cases since they can result from intended parameterization.
2935 if not Inside_A_Generic
and then not In_Instance
then
2937 -- Specialize msg if invalid values could make the loop
2938 -- non-null after all.
2940 if Compile_Time_Compare
2941 (L
, H
, Assume_Valid
=> False) = GT
2943 -- Since we know the range of the loop is null, set the
2944 -- appropriate flag to remove the loop entirely during
2947 Set_Is_Null_Loop
(Loop_Nod
);
2949 if Comes_From_Source
(N
) then
2951 ("??loop range is null, loop will not execute", DS
);
2954 -- Here is where the loop could execute because of
2955 -- invalid values, so issue appropriate message and in
2956 -- this case we do not set the Is_Null_Loop flag since
2957 -- the loop may execute.
2959 elsif Comes_From_Source
(N
) then
2961 ("??loop range may be null, loop may not execute",
2964 ("??can only execute if invalid values are present",
2969 -- In either case, suppress warnings in the body of the loop,
2970 -- since it is likely that these warnings will be inappropriate
2971 -- if the loop never actually executes, which is likely.
2973 Set_Suppress_Loop_Warnings
(Loop_Nod
);
2975 -- The other case for a warning is a reverse loop where the
2976 -- upper bound is the integer literal zero or one, and the
2977 -- lower bound may exceed this value.
2979 -- For example, we have
2981 -- for J in reverse N .. 1 loop
2983 -- In practice, this is very likely to be a case of reversing
2984 -- the bounds incorrectly in the range.
2986 elsif Reverse_Present
(N
)
2987 and then Nkind
(Original_Node
(H
)) = N_Integer_Literal
2989 (Intval
(Original_Node
(H
)) = Uint_0
2991 Intval
(Original_Node
(H
)) = Uint_1
)
2993 -- Lower bound may in fact be known and known not to exceed
2994 -- upper bound (e.g. reverse 0 .. 1) and that's OK.
2996 if Compile_Time_Known_Value
(L
)
2997 and then Expr_Value
(L
) <= Expr_Value
(H
)
3001 -- Otherwise warning is warranted
3004 Error_Msg_N
("??loop range may be null", DS
);
3005 Error_Msg_N
("\??bounds may be wrong way round", DS
);
3009 -- Check if either bound is known to be outside the range of the
3010 -- loop parameter type, this is e.g. the case of a loop from
3011 -- 20..X where the type is 1..19.
3013 -- Such a loop is dubious since either it raises CE or it executes
3014 -- zero times, and that cannot be useful!
3016 if Etype
(DS
) /= Any_Type
3017 and then not Error_Posted
(DS
)
3018 and then Nkind
(DS
) = N_Subtype_Indication
3019 and then Nkind
(Constraint
(DS
)) = N_Range_Constraint
3022 LLo
: constant Node_Id
:=
3023 Low_Bound
(Range_Expression
(Constraint
(DS
)));
3024 LHi
: constant Node_Id
:=
3025 High_Bound
(Range_Expression
(Constraint
(DS
)));
3027 Bad_Bound
: Node_Id
:= Empty
;
3028 -- Suspicious loop bound
3031 -- At this stage L, H are the bounds of the type, and LLo
3032 -- Lhi are the low bound and high bound of the loop.
3034 if Compile_Time_Compare
(LLo
, L
, Assume_Valid
=> True) = LT
3036 Compile_Time_Compare
(LLo
, H
, Assume_Valid
=> True) = GT
3041 if Compile_Time_Compare
(LHi
, L
, Assume_Valid
=> True) = LT
3043 Compile_Time_Compare
(LHi
, H
, Assume_Valid
=> True) = GT
3048 if Present
(Bad_Bound
) then
3050 ("suspicious loop bound out of range of "
3051 & "loop subtype??", Bad_Bound
);
3053 ("\loop executes zero times or raises "
3054 & "Constraint_Error??", Bad_Bound
);
3059 -- This declare block is about warnings, if we get an exception while
3060 -- testing for warnings, we simply abandon the attempt silently. This
3061 -- most likely occurs as the result of a previous error, but might
3062 -- just be an obscure case we have missed. In either case, not giving
3063 -- the warning is perfectly acceptable.
3066 when others => null;
3070 -- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)).
3071 -- This check is relevant only when SPARK_Mode is on as it is not a
3072 -- standard Ada legality check.
3074 if SPARK_Mode
= On
and then Is_Effectively_Volatile
(Id
) then
3075 Error_Msg_N
("loop parameter cannot be volatile", Id
);
3077 end Analyze_Loop_Parameter_Specification
;
3079 ----------------------------
3080 -- Analyze_Loop_Statement --
3081 ----------------------------
3083 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
3085 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean;
3086 -- Given a loop iteration scheme, determine whether it is an Ada 2012
3087 -- container iteration.
3089 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean;
3090 -- Determine whether loop statement N has been wrapped in a block to
3091 -- capture finalization actions that may be generated for container
3092 -- iterators. Prevents infinite recursion when block is analyzed.
3093 -- Routine is a noop if loop is single statement within source block.
3095 ---------------------------
3096 -- Is_Container_Iterator --
3097 ---------------------------
3099 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean is
3108 elsif Present
(Condition
(Iter
)) then
3111 -- for Def_Id in [reverse] Name loop
3112 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
3114 elsif Present
(Iterator_Specification
(Iter
)) then
3116 Nam
: constant Node_Id
:= Name
(Iterator_Specification
(Iter
));
3120 Nam_Copy
:= New_Copy_Tree
(Nam
);
3121 Set_Parent
(Nam_Copy
, Parent
(Nam
));
3122 Preanalyze_Range
(Nam_Copy
);
3124 -- The only two options here are iteration over a container or
3127 return not Is_Array_Type
(Etype
(Nam_Copy
));
3130 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
3134 LP
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3135 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(LP
);
3139 DS_Copy
:= New_Copy_Tree
(DS
);
3140 Set_Parent
(DS_Copy
, Parent
(DS
));
3141 Preanalyze_Range
(DS_Copy
);
3143 -- Check for a call to Iterate () or an expression with
3144 -- an iterator type.
3147 (Nkind
(DS_Copy
) = N_Function_Call
3148 and then Needs_Finalization
(Etype
(DS_Copy
)))
3149 or else Is_Iterator
(Etype
(DS_Copy
));
3152 end Is_Container_Iterator
;
3154 -------------------------
3155 -- Is_Wrapped_In_Block --
3156 -------------------------
3158 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean is
3164 -- Check if current scope is a block that is not a transient block.
3166 if Ekind
(Current_Scope
) /= E_Block
3167 or else No
(Block_Node
(Current_Scope
))
3173 Handled_Statement_Sequence
(Parent
(Block_Node
(Current_Scope
)));
3175 -- Skip leading pragmas that may be introduced for invariant and
3176 -- predicate checks.
3178 Stat
:= First
(Statements
(HSS
));
3179 while Present
(Stat
) and then Nkind
(Stat
) = N_Pragma
loop
3180 Stat
:= Next
(Stat
);
3183 return Stat
= N
and then No
(Next
(Stat
));
3185 end Is_Wrapped_In_Block
;
3187 -- Local declarations
3189 Id
: constant Node_Id
:= Identifier
(N
);
3190 Iter
: constant Node_Id
:= Iteration_Scheme
(N
);
3191 Loc
: constant Source_Ptr
:= Sloc
(N
);
3195 -- Start of processing for Analyze_Loop_Statement
3198 if Present
(Id
) then
3200 -- Make name visible, e.g. for use in exit statements. Loop labels
3201 -- are always considered to be referenced.
3206 -- Guard against serious error (typically, a scope mismatch when
3207 -- semantic analysis is requested) by creating loop entity to
3208 -- continue analysis.
3211 if Total_Errors_Detected
/= 0 then
3212 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3214 raise Program_Error
;
3217 -- Verify that the loop name is hot hidden by an unrelated
3218 -- declaration in an inner scope.
3220 elsif Ekind
(Ent
) /= E_Label
and then Ekind
(Ent
) /= E_Loop
then
3221 Error_Msg_Sloc
:= Sloc
(Ent
);
3222 Error_Msg_N
("implicit label declaration for & is hidden#", Id
);
3224 if Present
(Homonym
(Ent
))
3225 and then Ekind
(Homonym
(Ent
)) = E_Label
3227 Set_Entity
(Id
, Ent
);
3228 Set_Ekind
(Ent
, E_Loop
);
3232 Generate_Reference
(Ent
, N
, ' ');
3233 Generate_Definition
(Ent
);
3235 -- If we found a label, mark its type. If not, ignore it, since it
3236 -- means we have a conflicting declaration, which would already
3237 -- have been diagnosed at declaration time. Set Label_Construct
3238 -- of the implicit label declaration, which is not created by the
3239 -- parser for generic units.
3241 if Ekind
(Ent
) = E_Label
then
3242 Set_Ekind
(Ent
, E_Loop
);
3244 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
3245 Set_Label_Construct
(Parent
(Ent
), N
);
3250 -- Case of no identifier present. Create one and attach it to the
3251 -- loop statement for use as a scope and as a reference for later
3252 -- expansions. Indicate that the label does not come from source,
3253 -- and attach it to the loop statement so it is part of the tree,
3254 -- even without a full declaration.
3257 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3258 Set_Etype
(Ent
, Standard_Void_Type
);
3259 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Loc
));
3260 Set_Parent
(Ent
, N
);
3261 Set_Has_Created_Identifier
(N
);
3264 -- Iteration over a container in Ada 2012 involves the creation of a
3265 -- controlled iterator object. Wrap the loop in a block to ensure the
3266 -- timely finalization of the iterator and release of container locks.
3267 -- The same applies to the use of secondary stack when obtaining an
3270 if Ada_Version
>= Ada_2012
3271 and then Is_Container_Iterator
(Iter
)
3272 and then not Is_Wrapped_In_Block
(N
)
3275 Block_Nod
: Node_Id
;
3276 Block_Id
: Entity_Id
;
3280 Make_Block_Statement
(Loc
,
3281 Declarations
=> New_List
,
3282 Handled_Statement_Sequence
=>
3283 Make_Handled_Sequence_Of_Statements
(Loc
,
3284 Statements
=> New_List
(Relocate_Node
(N
))));
3286 Add_Block_Identifier
(Block_Nod
, Block_Id
);
3288 -- The expansion of iterator loops generates an iterator in order
3289 -- to traverse the elements of a container:
3291 -- Iter : <iterator type> := Iterate (Container)'reference;
3293 -- The iterator is controlled and returned on the secondary stack.
3294 -- The analysis of the call to Iterate establishes a transient
3295 -- scope to deal with the secondary stack management, but never
3296 -- really creates a physical block as this would kill the iterator
3297 -- too early (see Wrap_Transient_Declaration). To address this
3298 -- case, mark the generated block as needing secondary stack
3301 Set_Uses_Sec_Stack
(Block_Id
);
3303 Rewrite
(N
, Block_Nod
);
3309 -- Kill current values on entry to loop, since statements in the body of
3310 -- the loop may have been executed before the loop is entered. Similarly
3311 -- we kill values after the loop, since we do not know that the body of
3312 -- the loop was executed.
3314 Kill_Current_Values
;
3316 Analyze_Iteration_Scheme
(Iter
);
3318 -- Check for following case which merits a warning if the type E of is
3319 -- a multi-dimensional array (and no explicit subscript ranges present).
3325 and then Present
(Loop_Parameter_Specification
(Iter
))
3328 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3329 DSD
: constant Node_Id
:=
3330 Original_Node
(Discrete_Subtype_Definition
(LPS
));
3332 if Nkind
(DSD
) = N_Attribute_Reference
3333 and then Attribute_Name
(DSD
) = Name_Range
3334 and then No
(Expressions
(DSD
))
3337 Typ
: constant Entity_Id
:= Etype
(Prefix
(DSD
));
3339 if Is_Array_Type
(Typ
)
3340 and then Number_Dimensions
(Typ
) > 1
3341 and then Nkind
(Parent
(N
)) = N_Loop_Statement
3342 and then Present
(Iteration_Scheme
(Parent
(N
)))
3345 OIter
: constant Node_Id
:=
3346 Iteration_Scheme
(Parent
(N
));
3347 OLPS
: constant Node_Id
:=
3348 Loop_Parameter_Specification
(OIter
);
3349 ODSD
: constant Node_Id
:=
3350 Original_Node
(Discrete_Subtype_Definition
(OLPS
));
3352 if Nkind
(ODSD
) = N_Attribute_Reference
3353 and then Attribute_Name
(ODSD
) = Name_Range
3354 and then No
(Expressions
(ODSD
))
3355 and then Etype
(Prefix
(ODSD
)) = Typ
3357 Error_Msg_Sloc
:= Sloc
(ODSD
);
3359 ("inner range same as outer range#??", DSD
);
3368 -- Analyze the statements of the body except in the case of an Ada 2012
3369 -- iterator with the expander active. In this case the expander will do
3370 -- a rewrite of the loop into a while loop. We will then analyze the
3371 -- loop body when we analyze this while loop.
3373 -- We need to do this delay because if the container is for indefinite
3374 -- types the actual subtype of the components will only be determined
3375 -- when the cursor declaration is analyzed.
3377 -- If the expander is not active then we want to analyze the loop body
3378 -- now even in the Ada 2012 iterator case, since the rewriting will not
3379 -- be done. Insert the loop variable in the current scope, if not done
3380 -- when analysing the iteration scheme. Set its kind properly to detect
3381 -- improper uses in the loop body.
3383 -- In GNATprove mode, we do one of the above depending on the kind of
3384 -- loop. If it is an iterator over an array, then we do not analyze the
3385 -- loop now. We will analyze it after it has been rewritten by the
3386 -- special SPARK expansion which is activated in GNATprove mode. We need
3387 -- to do this so that other expansions that should occur in GNATprove
3388 -- mode take into account the specificities of the rewritten loop, in
3389 -- particular the introduction of a renaming (which needs to be
3392 -- In other cases in GNATprove mode then we want to analyze the loop
3393 -- body now, since no rewriting will occur.
3396 and then Present
(Iterator_Specification
(Iter
))
3399 and then Is_Iterator_Over_Array
(Iterator_Specification
(Iter
))
3403 elsif not Expander_Active
then
3405 I_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
3406 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3409 if Scope
(Id
) /= Current_Scope
then
3413 -- In an element iterator, The loop parameter is a variable if
3414 -- the domain of iteration (container or array) is a variable.
3416 if not Of_Present
(I_Spec
)
3417 or else not Is_Variable
(Name
(I_Spec
))
3419 Set_Ekind
(Id
, E_Loop_Parameter
);
3423 Analyze_Statements
(Statements
(N
));
3428 -- Pre-Ada2012 for-loops and while loops.
3430 Analyze_Statements
(Statements
(N
));
3433 -- When the iteration scheme of a loop contains attribute 'Loop_Entry,
3434 -- the loop is transformed into a conditional block. Retrieve the loop.
3438 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
3439 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
3442 -- Finish up processing for the loop. We kill all current values, since
3443 -- in general we don't know if the statements in the loop have been
3444 -- executed. We could do a bit better than this with a loop that we
3445 -- know will execute at least once, but it's not worth the trouble and
3446 -- the front end is not in the business of flow tracing.
3448 Process_End_Label
(Stmt
, 'e', Ent
);
3450 Kill_Current_Values
;
3452 -- Check for infinite loop. Skip check for generated code, since it
3453 -- justs waste time and makes debugging the routine called harder.
3455 -- Note that we have to wait till the body of the loop is fully analyzed
3456 -- before making this call, since Check_Infinite_Loop_Warning relies on
3457 -- being able to use semantic visibility information to find references.
3459 if Comes_From_Source
(Stmt
) then
3460 Check_Infinite_Loop_Warning
(Stmt
);
3463 -- Code after loop is unreachable if the loop has no WHILE or FOR and
3464 -- contains no EXIT statements within the body of the loop.
3466 if No
(Iter
) and then not Has_Exit
(Ent
) then
3467 Check_Unreachable_Code
(Stmt
);
3469 end Analyze_Loop_Statement
;
3471 ----------------------------
3472 -- Analyze_Null_Statement --
3473 ----------------------------
3475 -- Note: the semantics of the null statement is implemented by a single
3476 -- null statement, too bad everything isn't as simple as this.
3478 procedure Analyze_Null_Statement
(N
: Node_Id
) is
3479 pragma Warnings
(Off
, N
);
3482 end Analyze_Null_Statement
;
3484 ------------------------
3485 -- Analyze_Statements --
3486 ------------------------
3488 procedure Analyze_Statements
(L
: List_Id
) is
3493 -- The labels declared in the statement list are reachable from
3494 -- statements in the list. We do this as a prepass so that any goto
3495 -- statement will be properly flagged if its target is not reachable.
3496 -- This is not required, but is nice behavior.
3499 while Present
(S
) loop
3500 if Nkind
(S
) = N_Label
then
3501 Analyze
(Identifier
(S
));
3502 Lab
:= Entity
(Identifier
(S
));
3504 -- If we found a label mark it as reachable
3506 if Ekind
(Lab
) = E_Label
then
3507 Generate_Definition
(Lab
);
3508 Set_Reachable
(Lab
);
3510 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
3511 Set_Label_Construct
(Parent
(Lab
), S
);
3514 -- If we failed to find a label, it means the implicit declaration
3515 -- of the label was hidden. A for-loop parameter can do this to
3516 -- a label with the same name inside the loop, since the implicit
3517 -- label declaration is in the innermost enclosing body or block
3521 Error_Msg_Sloc
:= Sloc
(Lab
);
3523 ("implicit label declaration for & is hidden#",
3531 -- Perform semantic analysis on all statements
3533 Conditional_Statements_Begin
;
3536 while Present
(S
) loop
3539 -- Remove dimension in all statements
3541 Remove_Dimension_In_Statement
(S
);
3545 Conditional_Statements_End
;
3547 -- Make labels unreachable. Visibility is not sufficient, because labels
3548 -- in one if-branch for example are not reachable from the other branch,
3549 -- even though their declarations are in the enclosing declarative part.
3552 while Present
(S
) loop
3553 if Nkind
(S
) = N_Label
then
3554 Set_Reachable
(Entity
(Identifier
(S
)), False);
3559 end Analyze_Statements
;
3561 ----------------------------
3562 -- Check_Unreachable_Code --
3563 ----------------------------
3565 procedure Check_Unreachable_Code
(N
: Node_Id
) is
3566 Error_Node
: Node_Id
;
3570 if Is_List_Member
(N
) and then Comes_From_Source
(N
) then
3575 Nxt
:= Original_Node
(Next
(N
));
3577 -- Skip past pragmas
3579 while Nkind
(Nxt
) = N_Pragma
loop
3580 Nxt
:= Original_Node
(Next
(Nxt
));
3583 -- If a label follows us, then we never have dead code, since
3584 -- someone could branch to the label, so we just ignore it, unless
3585 -- we are in formal mode where goto statements are not allowed.
3587 if Nkind
(Nxt
) = N_Label
3588 and then not Restriction_Check_Required
(SPARK_05
)
3592 -- Otherwise see if we have a real statement following us
3595 and then Comes_From_Source
(Nxt
)
3596 and then Is_Statement
(Nxt
)
3598 -- Special very annoying exception. If we have a return that
3599 -- follows a raise, then we allow it without a warning, since
3600 -- the Ada RM annoyingly requires a useless return here.
3602 if Nkind
(Original_Node
(N
)) /= N_Raise_Statement
3603 or else Nkind
(Nxt
) /= N_Simple_Return_Statement
3605 -- The rather strange shenanigans with the warning message
3606 -- here reflects the fact that Kill_Dead_Code is very good
3607 -- at removing warnings in deleted code, and this is one
3608 -- warning we would prefer NOT to have removed.
3612 -- If we have unreachable code, analyze and remove the
3613 -- unreachable code, since it is useless and we don't
3614 -- want to generate junk warnings.
3616 -- We skip this step if we are not in code generation mode
3617 -- or CodePeer mode.
3619 -- This is the one case where we remove dead code in the
3620 -- semantics as opposed to the expander, and we do not want
3621 -- to remove code if we are not in code generation mode,
3622 -- since this messes up the ASIS trees or loses useful
3623 -- information in the CodePeer tree.
3625 -- Note that one might react by moving the whole circuit to
3626 -- exp_ch5, but then we lose the warning in -gnatc mode.
3628 if Operating_Mode
= Generate_Code
3629 and then not CodePeer_Mode
3634 -- Quit deleting when we have nothing more to delete
3635 -- or if we hit a label (since someone could transfer
3636 -- control to a label, so we should not delete it).
3638 exit when No
(Nxt
) or else Nkind
(Nxt
) = N_Label
;
3640 -- Statement/declaration is to be deleted
3644 Kill_Dead_Code
(Nxt
);
3648 -- Now issue the warning (or error in formal mode)
3650 if Restriction_Check_Required
(SPARK_05
) then
3651 Check_SPARK_05_Restriction
3652 ("unreachable code is not allowed", Error_Node
);
3654 Error_Msg
("??unreachable code!", Sloc
(Error_Node
));
3658 -- If the unconditional transfer of control instruction is the
3659 -- last statement of a sequence, then see if our parent is one of
3660 -- the constructs for which we count unblocked exits, and if so,
3661 -- adjust the count.
3666 -- Statements in THEN part or ELSE part of IF statement
3668 if Nkind
(P
) = N_If_Statement
then
3671 -- Statements in ELSIF part of an IF statement
3673 elsif Nkind
(P
) = N_Elsif_Part
then
3675 pragma Assert
(Nkind
(P
) = N_If_Statement
);
3677 -- Statements in CASE statement alternative
3679 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
3681 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
3683 -- Statements in body of block
3685 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
3686 and then Nkind
(Parent
(P
)) = N_Block_Statement
3688 -- The original loop is now placed inside a block statement
3689 -- due to the expansion of attribute 'Loop_Entry. Return as
3690 -- this is not a "real" block for the purposes of exit
3693 if Nkind
(N
) = N_Loop_Statement
3694 and then Subject_To_Loop_Entry_Attributes
(N
)
3699 -- Statements in exception handler in a block
3701 elsif Nkind
(P
) = N_Exception_Handler
3702 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
3703 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
3707 -- None of these cases, so return
3713 -- This was one of the cases we are looking for (i.e. the
3714 -- parent construct was IF, CASE or block) so decrement count.
3716 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
3720 end Check_Unreachable_Code
;
3722 ----------------------
3723 -- Preanalyze_Range --
3724 ----------------------
3726 procedure Preanalyze_Range
(R_Copy
: Node_Id
) is
3727 Save_Analysis
: constant Boolean := Full_Analysis
;
3731 Full_Analysis
:= False;
3732 Expander_Mode_Save_And_Set
(False);
3736 if Nkind
(R_Copy
) in N_Subexpr
and then Is_Overloaded
(R_Copy
) then
3738 -- Apply preference rules for range of predefined integer types, or
3739 -- diagnose true ambiguity.
3744 Found
: Entity_Id
:= Empty
;
3747 Get_First_Interp
(R_Copy
, I
, It
);
3748 while Present
(It
.Typ
) loop
3749 if Is_Discrete_Type
(It
.Typ
) then
3753 if Scope
(Found
) = Standard_Standard
then
3756 elsif Scope
(It
.Typ
) = Standard_Standard
then
3760 -- Both of them are user-defined
3763 ("ambiguous bounds in range of iteration", R_Copy
);
3764 Error_Msg_N
("\possible interpretations:", R_Copy
);
3765 Error_Msg_NE
("\\} ", R_Copy
, Found
);
3766 Error_Msg_NE
("\\} ", R_Copy
, It
.Typ
);
3772 Get_Next_Interp
(I
, It
);
3777 -- Subtype mark in iteration scheme
3779 if Is_Entity_Name
(R_Copy
) and then Is_Type
(Entity
(R_Copy
)) then
3782 -- Expression in range, or Ada 2012 iterator
3784 elsif Nkind
(R_Copy
) in N_Subexpr
then
3786 Typ
:= Etype
(R_Copy
);
3788 if Is_Discrete_Type
(Typ
) then
3791 -- Check that the resulting object is an iterable container
3793 elsif Has_Aspect
(Typ
, Aspect_Iterator_Element
)
3794 or else Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
3795 or else Has_Aspect
(Typ
, Aspect_Variable_Indexing
)
3799 -- The expression may yield an implicit reference to an iterable
3800 -- container. Insert explicit dereference so that proper type is
3801 -- visible in the loop.
3803 elsif Has_Implicit_Dereference
(Etype
(R_Copy
)) then
3808 Disc
:= First_Discriminant
(Typ
);
3809 while Present
(Disc
) loop
3810 if Has_Implicit_Dereference
(Disc
) then
3811 Build_Explicit_Dereference
(R_Copy
, Disc
);
3815 Next_Discriminant
(Disc
);
3822 Expander_Mode_Restore
;
3823 Full_Analysis
:= Save_Analysis
;
3824 end Preanalyze_Range
;