1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2015, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Errout
; use Errout
;
31 with Expander
; use Expander
;
32 with Exp_Ch6
; use Exp_Ch6
;
33 with Exp_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
;
44 with Rtsfind
; use Rtsfind
;
46 with Sem_Aux
; use Sem_Aux
;
47 with Sem_Case
; use Sem_Case
;
48 with Sem_Ch3
; use Sem_Ch3
;
49 with Sem_Ch6
; use Sem_Ch6
;
50 with Sem_Ch8
; use Sem_Ch8
;
51 with Sem_Dim
; use Sem_Dim
;
52 with Sem_Disp
; use Sem_Disp
;
53 with Sem_Elab
; use Sem_Elab
;
54 with Sem_Eval
; use Sem_Eval
;
55 with Sem_Res
; use Sem_Res
;
56 with Sem_Type
; use Sem_Type
;
57 with Sem_Util
; use Sem_Util
;
58 with Sem_Warn
; use Sem_Warn
;
59 with Snames
; use Snames
;
60 with Stand
; use Stand
;
61 with Sinfo
; use Sinfo
;
62 with Targparm
; use Targparm
;
63 with Tbuild
; use Tbuild
;
64 with Uintp
; use Uintp
;
66 package body Sem_Ch5
is
68 Unblocked_Exit_Count
: Nat
:= 0;
69 -- This variable is used when processing if statements, case statements,
70 -- and block statements. It counts the number of exit points that are not
71 -- blocked by unconditional transfer instructions: for IF and CASE, these
72 -- are the branches of the conditional; for a block, they are the statement
73 -- sequence of the block, and the statement sequences of any exception
74 -- handlers that are part of the block. When processing is complete, if
75 -- this count is zero, it means that control cannot fall through the IF,
76 -- CASE or block statement. This is used for the generation of warning
77 -- messages. This variable is recursively saved on entry to processing the
78 -- construct, and restored on exit.
80 procedure Preanalyze_Range
(R_Copy
: Node_Id
);
81 -- Determine expected type of range or domain of iteration of Ada 2012
82 -- loop by analyzing separate copy. Do the analysis and resolution of the
83 -- copy of the bound(s) with expansion disabled, to prevent the generation
84 -- of finalization actions. This prevents memory leaks when the bounds
85 -- contain calls to functions returning controlled arrays or when the
86 -- domain of iteration is a container.
88 ------------------------
89 -- Analyze_Assignment --
90 ------------------------
92 procedure Analyze_Assignment
(N
: Node_Id
) is
93 Lhs
: constant Node_Id
:= Name
(N
);
94 Rhs
: constant Node_Id
:= Expression
(N
);
99 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
);
100 -- N is the node for the left hand side of an assignment, and it is not
101 -- a variable. This routine issues an appropriate diagnostic.
104 -- This is called to kill current value settings of a simple variable
105 -- on the left hand side. We call it if we find any error in analyzing
106 -- the assignment, and at the end of processing before setting any new
107 -- current values in place.
109 procedure Set_Assignment_Type
111 Opnd_Type
: in out Entity_Id
);
112 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
113 -- nominal subtype. This procedure is used to deal with cases where the
114 -- nominal subtype must be replaced by the actual subtype.
116 -------------------------------
117 -- Diagnose_Non_Variable_Lhs --
118 -------------------------------
120 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
122 -- Not worth posting another error if left hand side already flagged
123 -- as being illegal in some respect.
125 if Error_Posted
(N
) then
128 -- Some special bad cases of entity names
130 elsif Is_Entity_Name
(N
) then
132 Ent
: constant Entity_Id
:= Entity
(N
);
135 if Ekind
(Ent
) = E_In_Parameter
then
137 ("assignment to IN mode parameter not allowed", N
);
140 -- Renamings of protected private components are turned into
141 -- constants when compiling a protected function. In the case
142 -- of single protected types, the private component appears
145 elsif (Is_Prival
(Ent
)
147 (Ekind
(Current_Scope
) = E_Function
148 or else Ekind
(Enclosing_Dynamic_Scope
149 (Current_Scope
)) = E_Function
))
151 (Ekind
(Ent
) = E_Component
152 and then Is_Protected_Type
(Scope
(Ent
)))
155 ("protected function cannot modify protected object", N
);
158 elsif Ekind
(Ent
) = E_Loop_Parameter
then
159 Error_Msg_N
("assignment to loop parameter not allowed", N
);
164 -- For indexed components, test prefix if it is in array. We do not
165 -- want to recurse for cases where the prefix is a pointer, since we
166 -- may get a message confusing the pointer and what it references.
168 elsif Nkind
(N
) = N_Indexed_Component
169 and then Is_Array_Type
(Etype
(Prefix
(N
)))
171 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
174 -- Another special case for assignment to discriminant
176 elsif Nkind
(N
) = N_Selected_Component
then
177 if Present
(Entity
(Selector_Name
(N
)))
178 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
180 Error_Msg_N
("assignment to discriminant not allowed", N
);
183 -- For selection from record, diagnose prefix, but note that again
184 -- we only do this for a record, not e.g. for a pointer.
186 elsif Is_Record_Type
(Etype
(Prefix
(N
))) then
187 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
192 -- If we fall through, we have no special message to issue
194 Error_Msg_N
("left hand side of assignment must be a variable", N
);
195 end Diagnose_Non_Variable_Lhs
;
201 procedure Kill_Lhs
is
203 if Is_Entity_Name
(Lhs
) then
205 Ent
: constant Entity_Id
:= Entity
(Lhs
);
207 if Present
(Ent
) then
208 Kill_Current_Values
(Ent
);
214 -------------------------
215 -- Set_Assignment_Type --
216 -------------------------
218 procedure Set_Assignment_Type
220 Opnd_Type
: in out Entity_Id
)
223 Require_Entity
(Opnd
);
225 -- If the assignment operand is an in-out or out parameter, then we
226 -- get the actual subtype (needed for the unconstrained case). If the
227 -- operand is the actual in an entry declaration, then within the
228 -- accept statement it is replaced with a local renaming, which may
229 -- also have an actual subtype.
231 if Is_Entity_Name
(Opnd
)
232 and then (Ekind
(Entity
(Opnd
)) = E_Out_Parameter
233 or else Ekind_In
(Entity
(Opnd
),
235 E_Generic_In_Out_Parameter
)
237 (Ekind
(Entity
(Opnd
)) = E_Variable
238 and then Nkind
(Parent
(Entity
(Opnd
))) =
239 N_Object_Renaming_Declaration
240 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
243 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
245 -- If assignment operand is a component reference, then we get the
246 -- actual subtype of the component for the unconstrained case.
248 elsif Nkind_In
(Opnd
, N_Selected_Component
, N_Explicit_Dereference
)
249 and then not Is_Unchecked_Union
(Opnd_Type
)
251 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
253 if Present
(Decl
) then
254 Insert_Action
(N
, Decl
);
255 Mark_Rewrite_Insertion
(Decl
);
257 Opnd_Type
:= Defining_Identifier
(Decl
);
258 Set_Etype
(Opnd
, Opnd_Type
);
259 Freeze_Itype
(Opnd_Type
, N
);
261 elsif Is_Constrained
(Etype
(Opnd
)) then
262 Opnd_Type
:= Etype
(Opnd
);
265 -- For slice, use the constrained subtype created for the slice
267 elsif Nkind
(Opnd
) = N_Slice
then
268 Opnd_Type
:= Etype
(Opnd
);
270 end Set_Assignment_Type
;
272 -- Start of processing for Analyze_Assignment
275 Mark_Coextensions
(N
, Rhs
);
277 -- Analyze the target of the assignment first in case the expression
278 -- contains references to Ghost entities. The checks that verify the
279 -- proper use of a Ghost entity need to know the enclosing context.
283 -- The left hand side of an assignment may reference an entity subject
284 -- to pragma Ghost with policy Ignore. Set the mode now to ensure that
285 -- any nodes generated during analysis and expansion are properly
286 -- flagged as ignored Ghost.
291 -- Ensure that we never do an assignment on a variable marked as
292 -- as Safe_To_Reevaluate.
294 pragma Assert
(not Is_Entity_Name
(Lhs
)
295 or else Ekind
(Entity
(Lhs
)) /= E_Variable
296 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
298 -- Start type analysis for assignment
302 -- In the most general case, both Lhs and Rhs can be overloaded, and we
303 -- must compute the intersection of the possible types on each side.
305 if Is_Overloaded
(Lhs
) then
312 Get_First_Interp
(Lhs
, I
, It
);
314 while Present
(It
.Typ
) loop
315 if Has_Compatible_Type
(Rhs
, It
.Typ
) then
316 if T1
/= Any_Type
then
318 -- An explicit dereference is overloaded if the prefix
319 -- is. Try to remove the ambiguity on the prefix, the
320 -- error will be posted there if the ambiguity is real.
322 if Nkind
(Lhs
) = N_Explicit_Dereference
then
325 PI1
: Interp_Index
:= 0;
331 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
333 while Present
(PIt
.Typ
) loop
334 if Is_Access_Type
(PIt
.Typ
)
335 and then Has_Compatible_Type
336 (Rhs
, Designated_Type
(PIt
.Typ
))
340 Disambiguate
(Prefix
(Lhs
),
343 if PIt
= No_Interp
then
345 ("ambiguous left-hand side"
346 & " in assignment", Lhs
);
349 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
359 Get_Next_Interp
(PI
, PIt
);
365 ("ambiguous left-hand side in assignment", Lhs
);
373 Get_Next_Interp
(I
, It
);
377 if T1
= Any_Type
then
379 ("no valid types for left-hand side for assignment", Lhs
);
385 -- The resulting assignment type is T1, so now we will resolve the left
386 -- hand side of the assignment using this determined type.
390 -- Cases where Lhs is not a variable
392 if not Is_Variable
(Lhs
) then
394 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
402 if Ada_Version
>= Ada_2005
then
404 -- Handle chains of renamings
407 while Nkind
(Ent
) in N_Has_Entity
408 and then Present
(Entity
(Ent
))
409 and then Present
(Renamed_Object
(Entity
(Ent
)))
411 Ent
:= Renamed_Object
(Entity
(Ent
));
414 if (Nkind
(Ent
) = N_Attribute_Reference
415 and then Attribute_Name
(Ent
) = Name_Priority
)
417 -- Renamings of the attribute Priority applied to protected
418 -- objects have been previously expanded into calls to the
419 -- Get_Ceiling run-time subprogram.
422 (Nkind
(Ent
) = N_Function_Call
423 and then (Entity
(Name
(Ent
)) = RTE
(RE_Get_Ceiling
)
425 Entity
(Name
(Ent
)) = RTE
(RO_PE_Get_Ceiling
)))
427 -- The enclosing subprogram cannot be a protected function
430 while not (Is_Subprogram
(S
)
431 and then Convention
(S
) = Convention_Protected
)
432 and then S
/= Standard_Standard
437 if Ekind
(S
) = E_Function
438 and then Convention
(S
) = Convention_Protected
441 ("protected function cannot modify protected object",
445 -- Changes of the ceiling priority of the protected object
446 -- are only effective if the Ceiling_Locking policy is in
447 -- effect (AARM D.5.2 (5/2)).
449 if Locking_Policy
/= 'C' then
450 Error_Msg_N
("assignment to the attribute PRIORITY has " &
452 Error_Msg_N
("\since no Locking_Policy has been " &
461 Diagnose_Non_Variable_Lhs
(Lhs
);
464 -- Error of assigning to limited type. We do however allow this in
465 -- certain cases where the front end generates the assignments.
467 elsif Is_Limited_Type
(T1
)
468 and then not Assignment_OK
(Lhs
)
469 and then not Assignment_OK
(Original_Node
(Lhs
))
470 and then not Is_Value_Type
(T1
)
472 -- CPP constructors can only be called in declarations
474 if Is_CPP_Constructor_Call
(Rhs
) then
475 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
478 ("left hand of assignment must not be limited type", Lhs
);
479 Explain_Limited_Type
(T1
, Lhs
);
483 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
484 -- abstract. This is only checked when the assignment Comes_From_Source,
485 -- because in some cases the expander generates such assignments (such
486 -- in the _assign operation for an abstract type).
488 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
490 ("target of assignment operation must not be abstract", Lhs
);
493 -- Resolution may have updated the subtype, in case the left-hand side
494 -- is a private protected component. Use the correct subtype to avoid
495 -- scoping issues in the back-end.
499 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
500 -- type. For example:
504 -- type Acc is access P.T;
507 -- with Pkg; use Acc;
508 -- procedure Example is
511 -- A.all := B.all; -- ERROR
514 if Nkind
(Lhs
) = N_Explicit_Dereference
515 and then Ekind
(T1
) = E_Incomplete_Type
517 Error_Msg_N
("invalid use of incomplete type", Lhs
);
522 -- Now we can complete the resolution of the right hand side
524 Set_Assignment_Type
(Lhs
, T1
);
527 -- This is the point at which we check for an unset reference
529 Check_Unset_Reference
(Rhs
);
530 Check_Unprotected_Access
(Lhs
, Rhs
);
532 -- Remaining steps are skipped if Rhs was syntactically in error
541 if not Covers
(T1
, T2
) then
542 Wrong_Type
(Rhs
, Etype
(Lhs
));
547 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
548 -- types, use the non-limited view if available
550 if Nkind
(Rhs
) = N_Explicit_Dereference
551 and then Is_Tagged_Type
(T2
)
552 and then Has_Non_Limited_View
(T2
)
554 T2
:= Non_Limited_View
(T2
);
557 Set_Assignment_Type
(Rhs
, T2
);
559 if Total_Errors_Detected
/= 0 then
569 if T1
= Any_Type
or else T2
= Any_Type
then
574 -- If the rhs is class-wide or dynamically tagged, then require the lhs
575 -- to be class-wide. The case where the rhs is a dynamically tagged call
576 -- to a dispatching operation with a controlling access result is
577 -- excluded from this check, since the target has an access type (and
578 -- no tag propagation occurs in that case).
580 if (Is_Class_Wide_Type
(T2
)
581 or else (Is_Dynamically_Tagged
(Rhs
)
582 and then not Is_Access_Type
(T1
)))
583 and then not Is_Class_Wide_Type
(T1
)
585 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
587 elsif Is_Class_Wide_Type
(T1
)
588 and then not Is_Class_Wide_Type
(T2
)
589 and then not Is_Tag_Indeterminate
(Rhs
)
590 and then not Is_Dynamically_Tagged
(Rhs
)
592 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
595 -- Propagate the tag from a class-wide target to the rhs when the rhs
596 -- is a tag-indeterminate call.
598 if Is_Tag_Indeterminate
(Rhs
) then
599 if Is_Class_Wide_Type
(T1
) then
600 Propagate_Tag
(Lhs
, Rhs
);
602 elsif Nkind
(Rhs
) = N_Function_Call
603 and then Is_Entity_Name
(Name
(Rhs
))
604 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
607 ("call to abstract function must be dispatching", Name
(Rhs
));
609 elsif Nkind
(Rhs
) = N_Qualified_Expression
610 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
611 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
613 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
616 ("call to abstract function must be dispatching",
617 Name
(Expression
(Rhs
)));
621 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
622 -- apply an implicit conversion of the rhs to that type to force
623 -- appropriate static and run-time accessibility checks. This applies
624 -- as well to anonymous access-to-subprogram types that are component
625 -- subtypes or formal parameters.
627 if Ada_Version
>= Ada_2005
and then Is_Access_Type
(T1
) then
628 if Is_Local_Anonymous_Access
(T1
)
629 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
631 -- Handle assignment to an Ada 2012 stand-alone object
632 -- of an anonymous access type.
634 or else (Ekind
(T1
) = E_Anonymous_Access_Type
635 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
636 N_Object_Declaration
)
639 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
640 Analyze_And_Resolve
(Rhs
, T1
);
644 -- Ada 2005 (AI-231): Assignment to not null variable
646 if Ada_Version
>= Ada_2005
647 and then Can_Never_Be_Null
(T1
)
648 and then not Assignment_OK
(Lhs
)
650 -- Case where we know the right hand side is null
652 if Known_Null
(Rhs
) then
653 Apply_Compile_Time_Constraint_Error
656 "(Ada 2005) null not allowed in null-excluding objects??",
657 Reason
=> CE_Null_Not_Allowed
);
659 -- We still mark this as a possible modification, that's necessary
660 -- to reset Is_True_Constant, and desirable for xref purposes.
662 Note_Possible_Modification
(Lhs
, Sure
=> True);
665 -- If we know the right hand side is non-null, then we convert to the
666 -- target type, since we don't need a run time check in that case.
668 elsif not Can_Never_Be_Null
(T2
) then
669 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
670 Analyze_And_Resolve
(Rhs
, T1
);
674 if Is_Scalar_Type
(T1
) then
675 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
677 -- For array types, verify that lengths match. If the right hand side
678 -- is a function call that has been inlined, the assignment has been
679 -- rewritten as a block, and the constraint check will be applied to the
680 -- assignment within the block.
682 elsif Is_Array_Type
(T1
)
683 and then (Nkind
(Rhs
) /= N_Type_Conversion
684 or else Is_Constrained
(Etype
(Rhs
)))
685 and then (Nkind
(Rhs
) /= N_Function_Call
686 or else Nkind
(N
) /= N_Block_Statement
)
688 -- Assignment verifies that the length of the Lsh and Rhs are equal,
689 -- but of course the indexes do not have to match. If the right-hand
690 -- side is a type conversion to an unconstrained type, a length check
691 -- is performed on the expression itself during expansion. In rare
692 -- cases, the redundant length check is computed on an index type
693 -- with a different representation, triggering incorrect code in the
696 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
699 -- Discriminant checks are applied in the course of expansion
704 -- Note: modifications of the Lhs may only be recorded after
705 -- checks have been applied.
707 Note_Possible_Modification
(Lhs
, Sure
=> True);
709 -- ??? a real accessibility check is needed when ???
711 -- Post warning for redundant assignment or variable to itself
713 if Warn_On_Redundant_Constructs
715 -- We only warn for source constructs
717 and then Comes_From_Source
(N
)
719 -- Where the object is the same on both sides
721 and then Same_Object
(Lhs
, Original_Node
(Rhs
))
723 -- But exclude the case where the right side was an operation that
724 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
725 -- don't want to warn in such a case, since it is reasonable to write
726 -- such expressions especially when K is defined symbolically in some
729 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
731 if Nkind
(Lhs
) in N_Has_Entity
then
732 Error_Msg_NE
-- CODEFIX
733 ("?r?useless assignment of & to itself!", N
, Entity
(Lhs
));
735 Error_Msg_N
-- CODEFIX
736 ("?r?useless assignment of object to itself!", N
);
740 -- Check for non-allowed composite assignment
742 if not Support_Composite_Assign_On_Target
743 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
744 and then (not Has_Size_Clause
(T1
) or else Esize
(T1
) > 64)
746 Error_Msg_CRT
("composite assignment", N
);
749 -- Check elaboration warning for left side if not in elab code
751 if not In_Subprogram_Or_Concurrent_Unit
then
752 Check_Elab_Assign
(Lhs
);
755 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
756 -- assignment is a source assignment in the extended main source unit.
757 -- We are not interested in any reference information outside this
758 -- context, or in compiler generated assignment statements.
760 if Comes_From_Source
(N
)
761 and then In_Extended_Main_Source_Unit
(Lhs
)
763 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
766 -- RM 7.3.2 (12/3) An assignment to a view conversion (from a type
767 -- to one of its ancestors) requires an invariant check. Apply check
768 -- only if expression comes from source, otherwise it will be applied
769 -- when value is assigned to source entity.
771 if Nkind
(Lhs
) = N_Type_Conversion
772 and then Has_Invariants
(Etype
(Expression
(Lhs
)))
773 and then Comes_From_Source
(Expression
(Lhs
))
775 Insert_After
(N
, Make_Invariant_Call
(Expression
(Lhs
)));
778 -- Final step. If left side is an entity, then we may be able to reset
779 -- the current tracked values to new safe values. We only have something
780 -- to do if the left side is an entity name, and expansion has not
781 -- modified the node into something other than an assignment, and of
782 -- course we only capture values if it is safe to do so.
784 if Is_Entity_Name
(Lhs
)
785 and then Nkind
(N
) = N_Assignment_Statement
788 Ent
: constant Entity_Id
:= Entity
(Lhs
);
791 if Safe_To_Capture_Value
(N
, Ent
) then
793 -- If simple variable on left side, warn if this assignment
794 -- blots out another one (rendering it useless). We only do
795 -- this for source assignments, otherwise we can generate bogus
796 -- warnings when an assignment is rewritten as another
797 -- assignment, and gets tied up with itself.
799 if Warn_On_Modified_Unread
800 and then Is_Assignable
(Ent
)
801 and then Comes_From_Source
(N
)
802 and then In_Extended_Main_Source_Unit
(Ent
)
804 Warn_On_Useless_Assignment
(Ent
, N
);
807 -- If we are assigning an access type and the left side is an
808 -- entity, then make sure that the Is_Known_[Non_]Null flags
809 -- properly reflect the state of the entity after assignment.
811 if Is_Access_Type
(T1
) then
812 if Known_Non_Null
(Rhs
) then
813 Set_Is_Known_Non_Null
(Ent
, True);
815 elsif Known_Null
(Rhs
)
816 and then not Can_Never_Be_Null
(Ent
)
818 Set_Is_Known_Null
(Ent
, True);
821 Set_Is_Known_Null
(Ent
, False);
823 if not Can_Never_Be_Null
(Ent
) then
824 Set_Is_Known_Non_Null
(Ent
, False);
828 -- For discrete types, we may be able to set the current value
829 -- if the value is known at compile time.
831 elsif Is_Discrete_Type
(T1
)
832 and then Compile_Time_Known_Value
(Rhs
)
834 Set_Current_Value
(Ent
, Rhs
);
836 Set_Current_Value
(Ent
, Empty
);
839 -- If not safe to capture values, kill them
847 -- If assigning to an object in whole or in part, note location of
848 -- assignment in case no one references value. We only do this for
849 -- source assignments, otherwise we can generate bogus warnings when an
850 -- assignment is rewritten as another assignment, and gets tied up with
854 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
857 and then Safe_To_Capture_Value
(N
, Ent
)
858 and then Nkind
(N
) = N_Assignment_Statement
859 and then Warn_On_Modified_Unread
860 and then Is_Assignable
(Ent
)
861 and then Comes_From_Source
(N
)
862 and then In_Extended_Main_Source_Unit
(Ent
)
864 Set_Last_Assignment
(Ent
, Lhs
);
868 Analyze_Dimension
(N
);
869 end Analyze_Assignment
;
871 -----------------------------
872 -- Analyze_Block_Statement --
873 -----------------------------
875 procedure Analyze_Block_Statement
(N
: Node_Id
) is
876 procedure Install_Return_Entities
(Scop
: Entity_Id
);
877 -- Install all entities of return statement scope Scop in the visibility
878 -- chain except for the return object since its entity is reused in a
881 -----------------------------
882 -- Install_Return_Entities --
883 -----------------------------
885 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
889 Id
:= First_Entity
(Scop
);
890 while Present
(Id
) loop
892 -- Do not install the return object
894 if not Ekind_In
(Id
, E_Constant
, E_Variable
)
895 or else not Is_Return_Object
(Id
)
902 end Install_Return_Entities
;
904 -- Local constants and variables
906 Decls
: constant List_Id
:= Declarations
(N
);
907 Id
: constant Node_Id
:= Identifier
(N
);
908 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
910 Is_BIP_Return_Statement
: Boolean;
912 -- Start of processing for Analyze_Block_Statement
915 -- In SPARK mode, we reject block statements. Note that the case of
916 -- block statements generated by the expander is fine.
918 if Nkind
(Original_Node
(N
)) = N_Block_Statement
then
919 Check_SPARK_05_Restriction
("block statement is not allowed", N
);
922 -- If no handled statement sequence is present, things are really messed
923 -- up, and we just return immediately (defence against previous errors).
926 Check_Error_Detected
;
930 -- Detect whether the block is actually a rewritten return statement of
931 -- a build-in-place function.
933 Is_BIP_Return_Statement
:=
935 and then Present
(Entity
(Id
))
936 and then Ekind
(Entity
(Id
)) = E_Return_Statement
937 and then Is_Build_In_Place_Function
938 (Return_Applies_To
(Entity
(Id
)));
940 -- Normal processing with HSS present
943 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
944 Ent
: Entity_Id
:= Empty
;
947 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
948 -- Recursively save value of this global, will be restored on exit
951 -- Initialize unblocked exit count for statements of begin block
952 -- plus one for each exception handler that is present.
954 Unblocked_Exit_Count
:= 1;
957 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ List_Length
(EH
);
960 -- If a label is present analyze it and mark it as referenced
966 -- An error defense. If we have an identifier, but no entity, then
967 -- something is wrong. If previous errors, then just remove the
968 -- identifier and continue, otherwise raise an exception.
971 Check_Error_Detected
;
972 Set_Identifier
(N
, Empty
);
975 Set_Ekind
(Ent
, E_Block
);
976 Generate_Reference
(Ent
, N
, ' ');
977 Generate_Definition
(Ent
);
979 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
980 Set_Label_Construct
(Parent
(Ent
), N
);
985 -- If no entity set, create a label entity
988 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
989 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
993 Set_Etype
(Ent
, Standard_Void_Type
);
994 Set_Block_Node
(Ent
, Identifier
(N
));
997 -- The block served as an extended return statement. Ensure that any
998 -- entities created during the analysis and expansion of the return
999 -- object declaration are once again visible.
1001 if Is_BIP_Return_Statement
then
1002 Install_Return_Entities
(Ent
);
1005 if Present
(Decls
) then
1006 Analyze_Declarations
(Decls
);
1008 Inspect_Deferred_Constant_Completion
(Decls
);
1012 Process_End_Label
(HSS
, 'e', Ent
);
1014 -- If exception handlers are present, then we indicate that enclosing
1015 -- scopes contain a block with handlers. We only need to mark non-
1018 if Present
(EH
) then
1021 Set_Has_Nested_Block_With_Handler
(S
);
1022 exit when Is_Overloadable
(S
)
1023 or else Ekind
(S
) = E_Package
1024 or else Is_Generic_Unit
(S
);
1029 Check_References
(Ent
);
1030 Warn_On_Useless_Assignments
(Ent
);
1033 if Unblocked_Exit_Count
= 0 then
1034 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1035 Check_Unreachable_Code
(N
);
1037 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1040 end Analyze_Block_Statement
;
1042 --------------------------------
1043 -- Analyze_Compound_Statement --
1044 --------------------------------
1046 procedure Analyze_Compound_Statement
(N
: Node_Id
) is
1048 Analyze_List
(Actions
(N
));
1049 end Analyze_Compound_Statement
;
1051 ----------------------------
1052 -- Analyze_Case_Statement --
1053 ----------------------------
1055 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1057 Exp_Type
: Entity_Id
;
1058 Exp_Btype
: Entity_Id
;
1061 Others_Present
: Boolean;
1062 -- Indicates if Others was present
1064 pragma Warnings
(Off
, Last_Choice
);
1065 -- Don't care about assigned value
1067 Statements_Analyzed
: Boolean := False;
1068 -- Set True if at least some statement sequences get analyzed. If False
1069 -- on exit, means we had a serious error that prevented full analysis of
1070 -- the case statement, and as a result it is not a good idea to output
1071 -- warning messages about unreachable code.
1073 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1074 -- Recursively save value of this global, will be restored on exit
1076 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1077 -- Error routine invoked by the generic instantiation below when the
1078 -- case statement has a non static choice.
1080 procedure Process_Statements
(Alternative
: Node_Id
);
1081 -- Analyzes the statements associated with a case alternative. Needed
1082 -- by instantiation below.
1084 package Analyze_Case_Choices
is new
1085 Generic_Analyze_Choices
1086 (Process_Associated_Node
=> Process_Statements
);
1087 use Analyze_Case_Choices
;
1088 -- Instantiation of the generic choice analysis package
1090 package Check_Case_Choices
is new
1091 Generic_Check_Choices
1092 (Process_Empty_Choice
=> No_OP
,
1093 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1094 Process_Associated_Node
=> No_OP
);
1095 use Check_Case_Choices
;
1096 -- Instantiation of the generic choice processing package
1098 -----------------------------
1099 -- Non_Static_Choice_Error --
1100 -----------------------------
1102 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1104 Flag_Non_Static_Expr
1105 ("choice given in case statement is not static!", Choice
);
1106 end Non_Static_Choice_Error
;
1108 ------------------------
1109 -- Process_Statements --
1110 ------------------------
1112 procedure Process_Statements
(Alternative
: Node_Id
) is
1113 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1117 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1118 Statements_Analyzed
:= True;
1120 -- An interesting optimization. If the case statement expression
1121 -- is a simple entity, then we can set the current value within an
1122 -- alternative if the alternative has one possible value.
1126 -- when 2 | 3 => beta
1127 -- when others => gamma
1129 -- Here we know that N is initially 1 within alpha, but for beta and
1130 -- gamma, we do not know anything more about the initial value.
1132 if Is_Entity_Name
(Exp
) then
1133 Ent
:= Entity
(Exp
);
1135 if Ekind_In
(Ent
, E_Variable
,
1139 if List_Length
(Choices
) = 1
1140 and then Nkind
(First
(Choices
)) in N_Subexpr
1141 and then Compile_Time_Known_Value
(First
(Choices
))
1143 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1146 Analyze_Statements
(Statements
(Alternative
));
1148 -- After analyzing the case, set the current value to empty
1149 -- since we won't know what it is for the next alternative
1150 -- (unless reset by this same circuit), or after the case.
1152 Set_Current_Value
(Entity
(Exp
), Empty
);
1157 -- Case where expression is not an entity name of a variable
1159 Analyze_Statements
(Statements
(Alternative
));
1160 end Process_Statements
;
1162 -- Start of processing for Analyze_Case_Statement
1165 Unblocked_Exit_Count
:= 0;
1166 Exp
:= Expression
(N
);
1169 -- The expression must be of any discrete type. In rare cases, the
1170 -- expander constructs a case statement whose expression has a private
1171 -- type whose full view is discrete. This can happen when generating
1172 -- a stream operation for a variant type after the type is frozen,
1173 -- when the partial of view of the type of the discriminant is private.
1174 -- In that case, use the full view to analyze case alternatives.
1176 if not Is_Overloaded
(Exp
)
1177 and then not Comes_From_Source
(N
)
1178 and then Is_Private_Type
(Etype
(Exp
))
1179 and then Present
(Full_View
(Etype
(Exp
)))
1180 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1182 Resolve
(Exp
, Etype
(Exp
));
1183 Exp_Type
:= Full_View
(Etype
(Exp
));
1186 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1187 Exp_Type
:= Etype
(Exp
);
1190 Check_Unset_Reference
(Exp
);
1191 Exp_Btype
:= Base_Type
(Exp_Type
);
1193 -- The expression must be of a discrete type which must be determinable
1194 -- independently of the context in which the expression occurs, but
1195 -- using the fact that the expression must be of a discrete type.
1196 -- Moreover, the type this expression must not be a character literal
1197 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1199 -- If error already reported by Resolve, nothing more to do
1201 if Exp_Btype
= Any_Discrete
or else Exp_Btype
= Any_Type
then
1204 elsif Exp_Btype
= Any_Character
then
1206 ("character literal as case expression is ambiguous", Exp
);
1209 elsif Ada_Version
= Ada_83
1210 and then (Is_Generic_Type
(Exp_Btype
)
1211 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1214 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1218 -- If the case expression is a formal object of mode in out, then treat
1219 -- it as having a nonstatic subtype by forcing use of the base type
1220 -- (which has to get passed to Check_Case_Choices below). Also use base
1221 -- type when the case expression is parenthesized.
1223 if Paren_Count
(Exp
) > 0
1224 or else (Is_Entity_Name
(Exp
)
1225 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1227 Exp_Type
:= Exp_Btype
;
1230 -- Call instantiated procedures to analyzwe and check discrete choices
1232 Analyze_Choices
(Alternatives
(N
), Exp_Type
);
1233 Check_Choices
(N
, Alternatives
(N
), Exp_Type
, Others_Present
);
1235 -- Case statement with single OTHERS alternative not allowed in SPARK
1237 if Others_Present
and then List_Length
(Alternatives
(N
)) = 1 then
1238 Check_SPARK_05_Restriction
1239 ("OTHERS as unique case alternative is not allowed", N
);
1242 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1243 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1246 -- If all our exits were blocked by unconditional transfers of control,
1247 -- then the entire CASE statement acts as an unconditional transfer of
1248 -- control, so treat it like one, and check unreachable code. Skip this
1249 -- test if we had serious errors preventing any statement analysis.
1251 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1252 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1253 Check_Unreachable_Code
(N
);
1255 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1258 -- If the expander is active it will detect the case of a statically
1259 -- determined single alternative and remove warnings for the case, but
1260 -- if we are not doing expansion, that circuit won't be active. Here we
1261 -- duplicate the effect of removing warnings in the same way, so that
1262 -- we will get the same set of warnings in -gnatc mode.
1264 if not Expander_Active
1265 and then Compile_Time_Known_Value
(Expression
(N
))
1266 and then Serious_Errors_Detected
= 0
1269 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1273 Alt
:= First
(Alternatives
(N
));
1274 while Present
(Alt
) loop
1275 if Alt
/= Chosen
then
1276 Remove_Warning_Messages
(Statements
(Alt
));
1283 end Analyze_Case_Statement
;
1285 ----------------------------
1286 -- Analyze_Exit_Statement --
1287 ----------------------------
1289 -- If the exit includes a name, it must be the name of a currently open
1290 -- loop. Otherwise there must be an innermost open loop on the stack, to
1291 -- which the statement implicitly refers.
1293 -- Additionally, in SPARK mode:
1295 -- The exit can only name the closest enclosing loop;
1297 -- An exit with a when clause must be directly contained in a loop;
1299 -- An exit without a when clause must be directly contained in an
1300 -- if-statement with no elsif or else, which is itself directly contained
1301 -- in a loop. The exit must be the last statement in the if-statement.
1303 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1304 Target
: constant Node_Id
:= Name
(N
);
1305 Cond
: constant Node_Id
:= Condition
(N
);
1306 Scope_Id
: Entity_Id
;
1312 Check_Unreachable_Code
(N
);
1315 if Present
(Target
) then
1317 U_Name
:= Entity
(Target
);
1319 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1320 Error_Msg_N
("invalid loop name in exit statement", N
);
1324 if Has_Loop_In_Inner_Open_Scopes
(U_Name
) then
1325 Check_SPARK_05_Restriction
1326 ("exit label must name the closest enclosing loop", N
);
1329 Set_Has_Exit
(U_Name
);
1336 for J
in reverse 0 .. Scope_Stack
.Last
loop
1337 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1338 Kind
:= Ekind
(Scope_Id
);
1340 if Kind
= E_Loop
and then (No
(Target
) or else Scope_Id
= U_Name
) then
1341 Set_Has_Exit
(Scope_Id
);
1344 elsif Kind
= E_Block
1345 or else Kind
= E_Loop
1346 or else Kind
= E_Return_Statement
1352 ("cannot exit from program unit or accept statement", N
);
1357 -- Verify that if present the condition is a Boolean expression
1359 if Present
(Cond
) then
1360 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1361 Check_Unset_Reference
(Cond
);
1364 -- In SPARK mode, verify that the exit statement respects the SPARK
1367 if Present
(Cond
) then
1368 if Nkind
(Parent
(N
)) /= N_Loop_Statement
then
1369 Check_SPARK_05_Restriction
1370 ("exit with when clause must be directly in loop", N
);
1374 if Nkind
(Parent
(N
)) /= N_If_Statement
then
1375 if Nkind
(Parent
(N
)) = N_Elsif_Part
then
1376 Check_SPARK_05_Restriction
1377 ("exit must be in IF without ELSIF", N
);
1379 Check_SPARK_05_Restriction
("exit must be directly in IF", N
);
1382 elsif Nkind
(Parent
(Parent
(N
))) /= N_Loop_Statement
then
1383 Check_SPARK_05_Restriction
1384 ("exit must be in IF directly in loop", N
);
1386 -- First test the presence of ELSE, so that an exit in an ELSE leads
1387 -- to an error mentioning the ELSE.
1389 elsif Present
(Else_Statements
(Parent
(N
))) then
1390 Check_SPARK_05_Restriction
("exit must be in IF without ELSE", N
);
1392 -- An exit in an ELSIF does not reach here, as it would have been
1393 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1395 elsif Present
(Elsif_Parts
(Parent
(N
))) then
1396 Check_SPARK_05_Restriction
("exit must be in IF without ELSIF", N
);
1400 -- Chain exit statement to associated loop entity
1402 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1403 Set_First_Exit_Statement
(Scope_Id
, N
);
1405 -- Since the exit may take us out of a loop, any previous assignment
1406 -- statement is not useless, so clear last assignment indications. It
1407 -- is OK to keep other current values, since if the exit statement
1408 -- does not exit, then the current values are still valid.
1410 Kill_Current_Values
(Last_Assignment_Only
=> True);
1411 end Analyze_Exit_Statement
;
1413 ----------------------------
1414 -- Analyze_Goto_Statement --
1415 ----------------------------
1417 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1418 Label
: constant Node_Id
:= Name
(N
);
1419 Scope_Id
: Entity_Id
;
1420 Label_Scope
: Entity_Id
;
1421 Label_Ent
: Entity_Id
;
1424 Check_SPARK_05_Restriction
("goto statement is not allowed", N
);
1426 -- Actual semantic checks
1428 Check_Unreachable_Code
(N
);
1429 Kill_Current_Values
(Last_Assignment_Only
=> True);
1432 Label_Ent
:= Entity
(Label
);
1434 -- Ignore previous error
1436 if Label_Ent
= Any_Id
then
1437 Check_Error_Detected
;
1440 -- We just have a label as the target of a goto
1442 elsif Ekind
(Label_Ent
) /= E_Label
then
1443 Error_Msg_N
("target of goto statement must be a label", Label
);
1446 -- Check that the target of the goto is reachable according to Ada
1447 -- scoping rules. Note: the special gotos we generate for optimizing
1448 -- local handling of exceptions would violate these rules, but we mark
1449 -- such gotos as analyzed when built, so this code is never entered.
1451 elsif not Reachable
(Label_Ent
) then
1452 Error_Msg_N
("target of goto statement is not reachable", Label
);
1456 -- Here if goto passes initial validity checks
1458 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1460 for J
in reverse 0 .. Scope_Stack
.Last
loop
1461 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1463 if Label_Scope
= Scope_Id
1464 or else not Ekind_In
(Scope_Id
, E_Block
, E_Loop
, E_Return_Statement
)
1466 if Scope_Id
/= Label_Scope
then
1468 ("cannot exit from program unit or accept statement", N
);
1475 raise Program_Error
;
1476 end Analyze_Goto_Statement
;
1478 --------------------------
1479 -- Analyze_If_Statement --
1480 --------------------------
1482 -- A special complication arises in the analysis of if statements
1484 -- The expander has circuitry to completely delete code that it can tell
1485 -- will not be executed (as a result of compile time known conditions). In
1486 -- the analyzer, we ensure that code that will be deleted in this manner
1487 -- is analyzed but not expanded. This is obviously more efficient, but
1488 -- more significantly, difficulties arise if code is expanded and then
1489 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1490 -- generated in deleted code must be frozen from start, because the nodes
1491 -- on which they depend will not be available at the freeze point.
1493 procedure Analyze_If_Statement
(N
: Node_Id
) is
1496 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1497 -- Recursively save value of this global, will be restored on exit
1499 Save_In_Deleted_Code
: Boolean;
1501 Del
: Boolean := False;
1502 -- This flag gets set True if a True condition has been found, which
1503 -- means that remaining ELSE/ELSIF parts are deleted.
1505 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1506 -- This is applied to either the N_If_Statement node itself or to an
1507 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1508 -- statements associated with it.
1510 -----------------------
1511 -- Analyze_Cond_Then --
1512 -----------------------
1514 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1515 Cond
: constant Node_Id
:= Condition
(Cnode
);
1516 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1519 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1520 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1521 Check_Unset_Reference
(Cond
);
1522 Set_Current_Value_Condition
(Cnode
);
1524 -- If already deleting, then just analyze then statements
1527 Analyze_Statements
(Tstm
);
1529 -- Compile time known value, not deleting yet
1531 elsif Compile_Time_Known_Value
(Cond
) then
1532 Save_In_Deleted_Code
:= In_Deleted_Code
;
1534 -- If condition is True, then analyze the THEN statements and set
1535 -- no expansion for ELSE and ELSIF parts.
1537 if Is_True
(Expr_Value
(Cond
)) then
1538 Analyze_Statements
(Tstm
);
1540 Expander_Mode_Save_And_Set
(False);
1541 In_Deleted_Code
:= True;
1543 -- If condition is False, analyze THEN with expansion off
1545 else -- Is_False (Expr_Value (Cond))
1546 Expander_Mode_Save_And_Set
(False);
1547 In_Deleted_Code
:= True;
1548 Analyze_Statements
(Tstm
);
1549 Expander_Mode_Restore
;
1550 In_Deleted_Code
:= Save_In_Deleted_Code
;
1553 -- Not known at compile time, not deleting, normal analysis
1556 Analyze_Statements
(Tstm
);
1558 end Analyze_Cond_Then
;
1560 -- Start of Analyze_If_Statement
1563 -- Initialize exit count for else statements. If there is no else part,
1564 -- this count will stay non-zero reflecting the fact that the uncovered
1565 -- else case is an unblocked exit.
1567 Unblocked_Exit_Count
:= 1;
1568 Analyze_Cond_Then
(N
);
1570 -- Now to analyze the elsif parts if any are present
1572 if Present
(Elsif_Parts
(N
)) then
1573 E
:= First
(Elsif_Parts
(N
));
1574 while Present
(E
) loop
1575 Analyze_Cond_Then
(E
);
1580 if Present
(Else_Statements
(N
)) then
1581 Analyze_Statements
(Else_Statements
(N
));
1584 -- If all our exits were blocked by unconditional transfers of control,
1585 -- then the entire IF statement acts as an unconditional transfer of
1586 -- control, so treat it like one, and check unreachable code.
1588 if Unblocked_Exit_Count
= 0 then
1589 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1590 Check_Unreachable_Code
(N
);
1592 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1596 Expander_Mode_Restore
;
1597 In_Deleted_Code
:= Save_In_Deleted_Code
;
1600 if not Expander_Active
1601 and then Compile_Time_Known_Value
(Condition
(N
))
1602 and then Serious_Errors_Detected
= 0
1604 if Is_True
(Expr_Value
(Condition
(N
))) then
1605 Remove_Warning_Messages
(Else_Statements
(N
));
1607 if Present
(Elsif_Parts
(N
)) then
1608 E
:= First
(Elsif_Parts
(N
));
1609 while Present
(E
) loop
1610 Remove_Warning_Messages
(Then_Statements
(E
));
1616 Remove_Warning_Messages
(Then_Statements
(N
));
1620 -- Warn on redundant if statement that has no effect
1622 -- Note, we could also check empty ELSIF parts ???
1624 if Warn_On_Redundant_Constructs
1626 -- If statement must be from source
1628 and then Comes_From_Source
(N
)
1630 -- Condition must not have obvious side effect
1632 and then Has_No_Obvious_Side_Effects
(Condition
(N
))
1634 -- No elsif parts of else part
1636 and then No
(Elsif_Parts
(N
))
1637 and then No
(Else_Statements
(N
))
1639 -- Then must be a single null statement
1641 and then List_Length
(Then_Statements
(N
)) = 1
1643 -- Go to original node, since we may have rewritten something as
1644 -- a null statement (e.g. a case we could figure the outcome of).
1647 T
: constant Node_Id
:= First
(Then_Statements
(N
));
1648 S
: constant Node_Id
:= Original_Node
(T
);
1651 if Comes_From_Source
(S
) and then Nkind
(S
) = N_Null_Statement
then
1652 Error_Msg_N
("if statement has no effect?r?", N
);
1656 end Analyze_If_Statement
;
1658 ----------------------------------------
1659 -- Analyze_Implicit_Label_Declaration --
1660 ----------------------------------------
1662 -- An implicit label declaration is generated in the innermost enclosing
1663 -- declarative part. This is done for labels, and block and loop names.
1665 -- Note: any changes in this routine may need to be reflected in
1666 -- Analyze_Label_Entity.
1668 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
1669 Id
: constant Node_Id
:= Defining_Identifier
(N
);
1672 Set_Ekind
(Id
, E_Label
);
1673 Set_Etype
(Id
, Standard_Void_Type
);
1674 Set_Enclosing_Scope
(Id
, Current_Scope
);
1675 end Analyze_Implicit_Label_Declaration
;
1677 ------------------------------
1678 -- Analyze_Iteration_Scheme --
1679 ------------------------------
1681 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
1683 Iter_Spec
: Node_Id
;
1684 Loop_Spec
: Node_Id
;
1687 -- For an infinite loop, there is no iteration scheme
1693 Cond
:= Condition
(N
);
1694 Iter_Spec
:= Iterator_Specification
(N
);
1695 Loop_Spec
:= Loop_Parameter_Specification
(N
);
1697 if Present
(Cond
) then
1698 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1699 Check_Unset_Reference
(Cond
);
1700 Set_Current_Value_Condition
(N
);
1702 elsif Present
(Iter_Spec
) then
1703 Analyze_Iterator_Specification
(Iter_Spec
);
1706 Analyze_Loop_Parameter_Specification
(Loop_Spec
);
1708 end Analyze_Iteration_Scheme
;
1710 ------------------------------------
1711 -- Analyze_Iterator_Specification --
1712 ------------------------------------
1714 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
1715 Loc
: constant Source_Ptr
:= Sloc
(N
);
1716 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
1717 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
1718 Iter_Name
: constant Node_Id
:= Name
(N
);
1724 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
);
1725 -- For an iteration over a container, if the loop carries the Reverse
1726 -- indicator, verify that the container type has an Iterate aspect that
1727 -- implements the reversible iterator interface.
1729 -----------------------------
1730 -- Check_Reverse_Iteration --
1731 -----------------------------
1733 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
) is
1735 if Reverse_Present
(N
)
1736 and then not Is_Array_Type
(Typ
)
1737 and then not Is_Reversible_Iterator
(Typ
)
1740 ("container type does not support reverse iteration", N
, Typ
);
1742 end Check_Reverse_Iteration
;
1744 -- Start of processing for Analyze_iterator_Specification
1747 Enter_Name
(Def_Id
);
1749 -- AI12-0151 specifies that when the subtype indication is present, it
1750 -- must statically match the type of the array or container element.
1751 -- To simplify this check, we introduce a subtype declaration with the
1752 -- given subtype indication when it carries a constraint, and rewrite
1753 -- the original as a reference to the created subtype entity.
1755 if Present
(Subt
) then
1756 if Nkind
(Subt
) = N_Subtype_Indication
then
1758 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
1759 Decl
: constant Node_Id
:=
1760 Make_Subtype_Declaration
(Loc
,
1761 Defining_Identifier
=> S
,
1762 Subtype_Indication
=> New_Copy_Tree
(Subt
));
1764 Insert_Before
(Parent
(Parent
(N
)), Decl
);
1766 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
1772 -- Save entity of subtype indication for subsequent check
1774 Bas
:= Entity
(Subt
);
1777 Preanalyze_Range
(Iter_Name
);
1779 -- Set the kind of the loop variable, which is not visible within
1780 -- the iterator name.
1782 Set_Ekind
(Def_Id
, E_Variable
);
1784 -- Provide a link between the iterator variable and the container, for
1785 -- subsequent use in cross-reference and modification information.
1787 if Of_Present
(N
) then
1788 Set_Related_Expression
(Def_Id
, Iter_Name
);
1790 -- For a container, the iterator is specified through the aspect
1792 if not Is_Array_Type
(Etype
(Iter_Name
)) then
1794 Iterator
: constant Entity_Id
:=
1795 Find_Value_Of_Aspect
1796 (Etype
(Iter_Name
), Aspect_Default_Iterator
);
1802 if No
(Iterator
) then
1803 null; -- error reported below.
1805 elsif not Is_Overloaded
(Iterator
) then
1806 Check_Reverse_Iteration
(Etype
(Iterator
));
1808 -- If Iterator is overloaded, use reversible iterator if
1809 -- one is available.
1811 elsif Is_Overloaded
(Iterator
) then
1812 Get_First_Interp
(Iterator
, I
, It
);
1813 while Present
(It
.Nam
) loop
1814 if Ekind
(It
.Nam
) = E_Function
1815 and then Is_Reversible_Iterator
(Etype
(It
.Nam
))
1817 Set_Etype
(Iterator
, It
.Typ
);
1818 Set_Entity
(Iterator
, It
.Nam
);
1822 Get_Next_Interp
(I
, It
);
1825 Check_Reverse_Iteration
(Etype
(Iterator
));
1831 -- If the domain of iteration is an expression, create a declaration for
1832 -- it, so that finalization actions are introduced outside of the loop.
1833 -- The declaration must be a renaming because the body of the loop may
1834 -- assign to elements.
1836 if not Is_Entity_Name
(Iter_Name
)
1838 -- When the context is a quantified expression, the renaming
1839 -- declaration is delayed until the expansion phase if we are
1842 and then (Nkind
(Parent
(N
)) /= N_Quantified_Expression
1843 or else Operating_Mode
= Check_Semantics
)
1845 -- Do not perform this expansion in SPARK mode, since the formal
1846 -- verification directly deals with the source form of the iterator.
1847 -- Ditto for ASIS, where the temporary may hide the transformation
1848 -- of a selected component into a prefixed function call.
1850 and then not GNATprove_Mode
1851 and then not ASIS_Mode
1854 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
1860 -- If the domain of iteration is an array component that depends
1861 -- on a discriminant, create actual subtype for it. Pre-analysis
1862 -- does not generate the actual subtype of a selected component.
1864 if Nkind
(Iter_Name
) = N_Selected_Component
1865 and then Is_Array_Type
(Etype
(Iter_Name
))
1868 Build_Actual_Subtype_Of_Component
1869 (Etype
(Selector_Name
(Iter_Name
)), Iter_Name
);
1870 Insert_Action
(N
, Act_S
);
1872 if Present
(Act_S
) then
1873 Typ
:= Defining_Identifier
(Act_S
);
1875 Typ
:= Etype
(Iter_Name
);
1879 Typ
:= Etype
(Iter_Name
);
1881 -- Verify that the expression produces an iterator
1883 if not Of_Present
(N
) and then not Is_Iterator
(Typ
)
1884 and then not Is_Array_Type
(Typ
)
1885 and then No
(Find_Aspect
(Typ
, Aspect_Iterable
))
1888 ("expect object that implements iterator interface",
1893 -- Protect against malformed iterator
1895 if Typ
= Any_Type
then
1896 Error_Msg_N
("invalid expression in loop iterator", Iter_Name
);
1900 if not Of_Present
(N
) then
1901 Check_Reverse_Iteration
(Typ
);
1904 -- The name in the renaming declaration may be a function call.
1905 -- Indicate that it does not come from source, to suppress
1906 -- spurious warnings on renamings of parameterless functions,
1907 -- a common enough idiom in user-defined iterators.
1910 Make_Object_Renaming_Declaration
(Loc
,
1911 Defining_Identifier
=> Id
,
1912 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
1914 New_Copy_Tree
(Iter_Name
, New_Sloc
=> Loc
));
1916 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
1917 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
1918 Set_Etype
(Id
, Typ
);
1919 Set_Etype
(Name
(N
), Typ
);
1922 -- Container is an entity or an array with uncontrolled components, or
1923 -- else it is a container iterator given by a function call, typically
1924 -- called Iterate in the case of predefined containers, even though
1925 -- Iterate is not a reserved name. What matters is that the return type
1926 -- of the function is an iterator type.
1928 elsif Is_Entity_Name
(Iter_Name
) then
1929 Analyze
(Iter_Name
);
1931 if Nkind
(Iter_Name
) = N_Function_Call
then
1933 C
: constant Node_Id
:= Name
(Iter_Name
);
1938 if not Is_Overloaded
(Iter_Name
) then
1939 Resolve
(Iter_Name
, Etype
(C
));
1942 Get_First_Interp
(C
, I
, It
);
1943 while It
.Typ
/= Empty
loop
1944 if Reverse_Present
(N
) then
1945 if Is_Reversible_Iterator
(It
.Typ
) then
1946 Resolve
(Iter_Name
, It
.Typ
);
1950 elsif Is_Iterator
(It
.Typ
) then
1951 Resolve
(Iter_Name
, It
.Typ
);
1955 Get_Next_Interp
(I
, It
);
1960 -- Domain of iteration is not overloaded
1963 Resolve
(Iter_Name
, Etype
(Iter_Name
));
1966 if not Of_Present
(N
) then
1967 Check_Reverse_Iteration
(Etype
(Iter_Name
));
1971 -- Get base type of container, for proper retrieval of Cursor type
1972 -- and primitive operations.
1974 Typ
:= Base_Type
(Etype
(Iter_Name
));
1976 if Is_Array_Type
(Typ
) then
1977 if Of_Present
(N
) then
1978 Set_Etype
(Def_Id
, Component_Type
(Typ
));
1980 -- AI12-0151 stipulates that the container cannot be a component
1981 -- that depends on a discriminant if the enclosing object is
1982 -- mutable, to prevent a modification of the container in the
1983 -- course of an iteration.
1985 if Is_Entity_Name
(Iter_Name
)
1986 and then Nkind
(Original_Node
(Iter_Name
)) = N_Selected_Component
1987 and then Is_Dependent_Component_Of_Mutable_Object
1988 (Renamed_Object
(Entity
(Iter_Name
)))
1991 ("container cannot be a discriminant-dependent "
1992 & "component of a mutable object", N
);
1997 (Base_Type
(Bas
) /= Base_Type
(Component_Type
(Typ
))
1999 not Subtypes_Statically_Match
(Bas
, Component_Type
(Typ
)))
2002 ("subtype indication does not match component type", Subt
);
2005 -- Here we have a missing Range attribute
2009 ("missing Range attribute in iteration over an array", N
);
2011 -- In Ada 2012 mode, this may be an attempt at an iterator
2013 if Ada_Version
>= Ada_2012
then
2015 ("\if& is meant to designate an element of the array, use OF",
2019 -- Prevent cascaded errors
2021 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2022 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2025 -- Check for type error in iterator
2027 elsif Typ
= Any_Type
then
2030 -- Iteration over a container
2033 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2034 Error_Msg_Ada_2012_Feature
("container iterator", Sloc
(N
));
2038 if Of_Present
(N
) then
2039 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2041 Elt
: constant Entity_Id
:=
2042 Get_Iterable_Type_Primitive
(Typ
, Name_Element
);
2046 ("missing Element primitive for iteration", N
);
2048 Set_Etype
(Def_Id
, Etype
(Elt
));
2052 -- For a predefined container, The type of the loop variable is
2053 -- the Iterator_Element aspect of the container type.
2057 Element
: constant Entity_Id
:=
2058 Find_Value_Of_Aspect
(Typ
, Aspect_Iterator_Element
);
2061 if No
(Element
) then
2062 Error_Msg_NE
("cannot iterate over&", N
, Typ
);
2066 Set_Etype
(Def_Id
, Entity
(Element
));
2068 -- If subtype indication was given, verify that it covers
2069 -- the element type of the container.
2072 and then (not Covers
(Bas
, Etype
(Def_Id
))
2073 or else not Subtypes_Statically_Match
2074 (Bas
, Etype
(Def_Id
)))
2077 ("subtype indication does not match element type",
2081 -- If the container has a variable indexing aspect, the
2082 -- element is a variable and is modifiable in the loop.
2084 if Has_Aspect
(Typ
, Aspect_Variable_Indexing
) then
2085 Set_Ekind
(Def_Id
, E_Variable
);
2091 -- IN iterator, domain is a range, or a call to Iterate function
2094 -- For an iteration of the form IN, the name must denote an
2095 -- iterator, typically the result of a call to Iterate. Give a
2096 -- useful error message when the name is a container by itself.
2098 -- The type may be a formal container type, which has to have
2099 -- an Iterable aspect detailing the required primitives.
2101 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2102 and then not Is_Iterator
(Typ
)
2104 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2107 elsif not Has_Aspect
(Typ
, Aspect_Iterator_Element
) then
2109 ("cannot iterate over&", Name
(N
), Typ
);
2112 ("name must be an iterator, not a container", Name
(N
));
2115 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2119 ("\to iterate directly over the elements of a container, "
2120 & "write `of &`", Name
(N
), Original_Node
(Name
(N
)));
2122 -- No point in continuing analysis of iterator spec
2128 -- If the name is a call (typically prefixed) to some Iterate
2129 -- function, it has been rewritten as an object declaration.
2130 -- If that object is a selected component, verify that it is not
2131 -- a component of an unconstrained mutable object.
2133 if Nkind
(Iter_Name
) = N_Identifier
then
2135 Iter_Kind
: constant Node_Kind
:=
2136 Nkind
(Original_Node
(Iter_Name
));
2140 if Iter_Kind
= N_Selected_Component
then
2141 Obj
:= Prefix
(Original_Node
(Iter_Name
));
2143 elsif Iter_Kind
= N_Function_Call
then
2144 Obj
:= First_Actual
(Original_Node
(Iter_Name
));
2147 if Nkind
(Obj
) = N_Selected_Component
2148 and then Is_Dependent_Component_Of_Mutable_Object
(Obj
)
2151 ("container cannot be a discriminant-dependent " &
2152 "component of a mutable object", N
);
2157 -- The result type of Iterate function is the classwide type of
2158 -- the interface parent. We need the specific Cursor type defined
2159 -- in the container package. We obtain it by name for a predefined
2160 -- container, or through the Iterable aspect for a formal one.
2162 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2165 (Parent
(Find_Value_Of_Aspect
(Typ
, Aspect_Iterable
)),
2167 Ent
:= Etype
(Def_Id
);
2170 Ent
:= First_Entity
(Scope
(Typ
));
2171 while Present
(Ent
) loop
2172 if Chars
(Ent
) = Name_Cursor
then
2173 Set_Etype
(Def_Id
, Etype
(Ent
));
2181 -- The cursor is the target of generated assignments in the
2182 -- loop, and cannot have a limited type.
2184 if Is_Limited_Type
(Etype
(Def_Id
)) then
2185 Error_Msg_N
("cursor type cannot be limited", N
);
2190 -- A loop parameter cannot be effectively volatile. This check is
2191 -- peformed only when SPARK_Mode is on as it is not a standard Ada
2192 -- legality check (SPARK RM 7.1.3(6)).
2194 -- Not clear whether this applies to element iterators, where the
2195 -- cursor is not an explicit entity ???
2198 and then not Of_Present
(N
)
2199 and then Is_Effectively_Volatile
(Ent
)
2201 Error_Msg_N
("loop parameter cannot be volatile", Ent
);
2203 end Analyze_Iterator_Specification
;
2209 -- Note: the semantic work required for analyzing labels (setting them as
2210 -- reachable) was done in a prepass through the statements in the block,
2211 -- so that forward gotos would be properly handled. See Analyze_Statements
2212 -- for further details. The only processing required here is to deal with
2213 -- optimizations that depend on an assumption of sequential control flow,
2214 -- since of course the occurrence of a label breaks this assumption.
2216 procedure Analyze_Label
(N
: Node_Id
) is
2217 pragma Warnings
(Off
, N
);
2219 Kill_Current_Values
;
2222 --------------------------
2223 -- Analyze_Label_Entity --
2224 --------------------------
2226 procedure Analyze_Label_Entity
(E
: Entity_Id
) is
2228 Set_Ekind
(E
, E_Label
);
2229 Set_Etype
(E
, Standard_Void_Type
);
2230 Set_Enclosing_Scope
(E
, Current_Scope
);
2231 Set_Reachable
(E
, True);
2232 end Analyze_Label_Entity
;
2234 ------------------------------------------
2235 -- Analyze_Loop_Parameter_Specification --
2236 ------------------------------------------
2238 procedure Analyze_Loop_Parameter_Specification
(N
: Node_Id
) is
2239 Loop_Nod
: constant Node_Id
:= Parent
(Parent
(N
));
2241 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
2242 -- If the bounds are given by a 'Range reference on a function call
2243 -- that returns a controlled array, introduce an explicit declaration
2244 -- to capture the bounds, so that the function result can be finalized
2245 -- in timely fashion.
2247 procedure Check_Predicate_Use
(T
: Entity_Id
);
2248 -- Diagnose Attempt to iterate through non-static predicate. Note that
2249 -- a type with inherited predicates may have both static and dynamic
2250 -- forms. In this case it is not sufficent to check the static predicate
2251 -- function only, look for a dynamic predicate aspect as well.
2253 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean;
2254 -- N is the node for an arbitrary construct. This function searches the
2255 -- construct N to see if any expressions within it contain function
2256 -- calls that use the secondary stack, returning True if any such call
2257 -- is found, and False otherwise.
2259 procedure Process_Bounds
(R
: Node_Id
);
2260 -- If the iteration is given by a range, create temporaries and
2261 -- assignment statements block to capture the bounds and perform
2262 -- required finalization actions in case a bound includes a function
2263 -- call that uses the temporary stack. We first pre-analyze a copy of
2264 -- the range in order to determine the expected type, and analyze and
2265 -- resolve the original bounds.
2267 --------------------------------------
2268 -- Check_Controlled_Array_Attribute --
2269 --------------------------------------
2271 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
2273 if Nkind
(DS
) = N_Attribute_Reference
2274 and then Is_Entity_Name
(Prefix
(DS
))
2275 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
2276 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
2278 Is_Controlled
(Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
2279 and then Expander_Active
2282 Loc
: constant Source_Ptr
:= Sloc
(N
);
2283 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
2284 Indx
: constant Entity_Id
:=
2285 Base_Type
(Etype
(First_Index
(Arr
)));
2286 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
2291 Make_Subtype_Declaration
(Loc
,
2292 Defining_Identifier
=> Subt
,
2293 Subtype_Indication
=>
2294 Make_Subtype_Indication
(Loc
,
2295 Subtype_Mark
=> New_Occurrence_Of
(Indx
, Loc
),
2297 Make_Range_Constraint
(Loc
, Relocate_Node
(DS
))));
2298 Insert_Before
(Loop_Nod
, Decl
);
2302 Make_Attribute_Reference
(Loc
,
2303 Prefix
=> New_Occurrence_Of
(Subt
, Loc
),
2304 Attribute_Name
=> Attribute_Name
(DS
)));
2309 end Check_Controlled_Array_Attribute
;
2311 -------------------------
2312 -- Check_Predicate_Use --
2313 -------------------------
2315 procedure Check_Predicate_Use
(T
: Entity_Id
) is
2317 -- A predicated subtype is illegal in loops and related constructs
2318 -- if the predicate is not static, or if it is a non-static subtype
2319 -- of a statically predicated subtype.
2321 if Is_Discrete_Type
(T
)
2322 and then Has_Predicates
(T
)
2323 and then (not Has_Static_Predicate
(T
)
2324 or else not Is_Static_Subtype
(T
)
2325 or else Has_Dynamic_Predicate_Aspect
(T
))
2327 -- Seems a confusing message for the case of a static predicate
2328 -- with a non-static subtype???
2330 Bad_Predicated_Subtype_Use
2331 ("cannot use subtype& with non-static predicate for loop "
2332 & "iteration", Discrete_Subtype_Definition
(N
),
2333 T
, Suggest_Static
=> True);
2335 elsif Inside_A_Generic
and then Is_Generic_Formal
(T
) then
2336 Set_No_Dynamic_Predicate_On_Actual
(T
);
2338 end Check_Predicate_Use
;
2340 ------------------------------------
2341 -- Has_Call_Using_Secondary_Stack --
2342 ------------------------------------
2344 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean is
2346 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
2347 -- Check if N is a function call which uses the secondary stack
2353 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
2356 Return_Typ
: Entity_Id
;
2359 if Nkind
(N
) = N_Function_Call
then
2362 -- Call using access to subprogram with explicit dereference
2364 if Nkind
(Nam
) = N_Explicit_Dereference
then
2365 Subp
:= Etype
(Nam
);
2367 -- Call using a selected component notation or Ada 2005 object
2368 -- operation notation
2370 elsif Nkind
(Nam
) = N_Selected_Component
then
2371 Subp
:= Entity
(Selector_Name
(Nam
));
2376 Subp
:= Entity
(Nam
);
2379 Return_Typ
:= Etype
(Subp
);
2381 if Is_Composite_Type
(Return_Typ
)
2382 and then not Is_Constrained
(Return_Typ
)
2386 elsif Sec_Stack_Needed_For_Return
(Subp
) then
2391 -- Continue traversing the tree
2396 function Check_Calls
is new Traverse_Func
(Check_Call
);
2398 -- Start of processing for Has_Call_Using_Secondary_Stack
2401 return Check_Calls
(N
) = Abandon
;
2402 end Has_Call_Using_Secondary_Stack
;
2404 --------------------
2405 -- Process_Bounds --
2406 --------------------
2408 procedure Process_Bounds
(R
: Node_Id
) is
2409 Loc
: constant Source_Ptr
:= Sloc
(N
);
2412 (Original_Bound
: Node_Id
;
2413 Analyzed_Bound
: Node_Id
;
2414 Typ
: Entity_Id
) return Node_Id
;
2415 -- Capture value of bound and return captured value
2422 (Original_Bound
: Node_Id
;
2423 Analyzed_Bound
: Node_Id
;
2424 Typ
: Entity_Id
) return Node_Id
2431 -- If the bound is a constant or an object, no need for a separate
2432 -- declaration. If the bound is the result of previous expansion
2433 -- it is already analyzed and should not be modified. Note that
2434 -- the Bound will be resolved later, if needed, as part of the
2435 -- call to Make_Index (literal bounds may need to be resolved to
2438 if Analyzed
(Original_Bound
) then
2439 return Original_Bound
;
2441 elsif Nkind_In
(Analyzed_Bound
, N_Integer_Literal
,
2442 N_Character_Literal
)
2443 or else Is_Entity_Name
(Analyzed_Bound
)
2445 Analyze_And_Resolve
(Original_Bound
, Typ
);
2446 return Original_Bound
;
2449 -- Normally, the best approach is simply to generate a constant
2450 -- declaration that captures the bound. However, there is a nasty
2451 -- case where this is wrong. If the bound is complex, and has a
2452 -- possible use of the secondary stack, we need to generate a
2453 -- separate assignment statement to ensure the creation of a block
2454 -- which will release the secondary stack.
2456 -- We prefer the constant declaration, since it leaves us with a
2457 -- proper trace of the value, useful in optimizations that get rid
2458 -- of junk range checks.
2460 if not Has_Call_Using_Secondary_Stack
(Analyzed_Bound
) then
2461 Analyze_And_Resolve
(Original_Bound
, Typ
);
2463 -- Ensure that the bound is valid. This check should not be
2464 -- generated when the range belongs to a quantified expression
2465 -- as the construct is still not expanded into its final form.
2467 if Nkind
(Parent
(R
)) /= N_Loop_Parameter_Specification
2468 or else Nkind
(Parent
(Parent
(R
))) /= N_Quantified_Expression
2470 Ensure_Valid
(Original_Bound
);
2473 Force_Evaluation
(Original_Bound
);
2474 return Original_Bound
;
2477 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
2479 -- Here we make a declaration with a separate assignment
2480 -- statement, and insert before loop header.
2483 Make_Object_Declaration
(Loc
,
2484 Defining_Identifier
=> Id
,
2485 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
2488 Make_Assignment_Statement
(Loc
,
2489 Name
=> New_Occurrence_Of
(Id
, Loc
),
2490 Expression
=> Relocate_Node
(Original_Bound
));
2492 Insert_Actions
(Loop_Nod
, New_List
(Decl
, Assign
));
2494 -- Now that this temporary variable is initialized we decorate it
2495 -- as safe-to-reevaluate to inform to the backend that no further
2496 -- asignment will be issued and hence it can be handled as side
2497 -- effect free. Note that this decoration must be done when the
2498 -- assignment has been analyzed because otherwise it will be
2499 -- rejected (see Analyze_Assignment).
2501 Set_Is_Safe_To_Reevaluate
(Id
);
2503 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
2505 if Nkind
(Assign
) = N_Assignment_Statement
then
2506 return Expression
(Assign
);
2508 return Original_Bound
;
2512 Hi
: constant Node_Id
:= High_Bound
(R
);
2513 Lo
: constant Node_Id
:= Low_Bound
(R
);
2514 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
2519 -- Start of processing for Process_Bounds
2522 Set_Parent
(R_Copy
, Parent
(R
));
2523 Preanalyze_Range
(R_Copy
);
2524 Typ
:= Etype
(R_Copy
);
2526 -- If the type of the discrete range is Universal_Integer, then the
2527 -- bound's type must be resolved to Integer, and any object used to
2528 -- hold the bound must also have type Integer, unless the literal
2529 -- bounds are constant-folded expressions with a user-defined type.
2531 if Typ
= Universal_Integer
then
2532 if Nkind
(Lo
) = N_Integer_Literal
2533 and then Present
(Etype
(Lo
))
2534 and then Scope
(Etype
(Lo
)) /= Standard_Standard
2538 elsif Nkind
(Hi
) = N_Integer_Literal
2539 and then Present
(Etype
(Hi
))
2540 and then Scope
(Etype
(Hi
)) /= Standard_Standard
2545 Typ
:= Standard_Integer
;
2551 New_Lo
:= One_Bound
(Lo
, Low_Bound
(R_Copy
), Typ
);
2552 New_Hi
:= One_Bound
(Hi
, High_Bound
(R_Copy
), Typ
);
2554 -- Propagate staticness to loop range itself, in case the
2555 -- corresponding subtype is static.
2557 if New_Lo
/= Lo
and then Is_OK_Static_Expression
(New_Lo
) then
2558 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo
));
2561 if New_Hi
/= Hi
and then Is_OK_Static_Expression
(New_Hi
) then
2562 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi
));
2568 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(N
);
2569 Id
: constant Entity_Id
:= Defining_Identifier
(N
);
2573 -- Start of processing for Analyze_Loop_Parameter_Specification
2578 -- We always consider the loop variable to be referenced, since the loop
2579 -- may be used just for counting purposes.
2581 Generate_Reference
(Id
, N
, ' ');
2583 -- Check for the case of loop variable hiding a local variable (used
2584 -- later on to give a nice warning if the hidden variable is never
2588 H
: constant Entity_Id
:= Homonym
(Id
);
2591 and then Ekind
(H
) = E_Variable
2592 and then Is_Discrete_Type
(Etype
(H
))
2593 and then Enclosing_Dynamic_Scope
(H
) = Enclosing_Dynamic_Scope
(Id
)
2595 Set_Hiding_Loop_Variable
(H
, Id
);
2599 -- Loop parameter specification must include subtype mark in SPARK
2601 if Nkind
(DS
) = N_Range
then
2602 Check_SPARK_05_Restriction
2603 ("loop parameter specification must include subtype mark", N
);
2606 -- Analyze the subtype definition and create temporaries for the bounds.
2607 -- Do not evaluate the range when preanalyzing a quantified expression
2608 -- because bounds expressed as function calls with side effects will be
2609 -- incorrectly replicated.
2611 if Nkind
(DS
) = N_Range
2612 and then Expander_Active
2613 and then Nkind
(Parent
(N
)) /= N_Quantified_Expression
2615 Process_Bounds
(DS
);
2617 -- Either the expander not active or the range of iteration is a subtype
2618 -- indication, an entity, or a function call that yields an aggregate or
2622 DS_Copy
:= New_Copy_Tree
(DS
);
2623 Set_Parent
(DS_Copy
, Parent
(DS
));
2624 Preanalyze_Range
(DS_Copy
);
2626 -- Ada 2012: If the domain of iteration is:
2628 -- a) a function call,
2629 -- b) an identifier that is not a type,
2630 -- c) an attribute reference 'Old (within a postcondition)
2631 -- d) an unchecked conversion
2633 -- then it is an iteration over a container. It was classified as
2634 -- a loop specification by the parser, and must be rewritten now
2635 -- to activate container iteration. The last case will occur within
2636 -- an expanded inlined call, where the expansion wraps an actual in
2637 -- an unchecked conversion when needed. The expression of the
2638 -- conversion is always an object.
2640 if Nkind
(DS_Copy
) = N_Function_Call
2641 or else (Is_Entity_Name
(DS_Copy
)
2642 and then not Is_Type
(Entity
(DS_Copy
)))
2643 or else (Nkind
(DS_Copy
) = N_Attribute_Reference
2644 and then Nam_In
(Attribute_Name
(DS_Copy
),
2645 Name_Old
, Name_Loop_Entry
))
2646 or else Nkind
(DS_Copy
) = N_Unchecked_Type_Conversion
2647 or else Has_Aspect
(Etype
(DS_Copy
), Aspect_Iterable
)
2649 -- This is an iterator specification. Rewrite it as such and
2650 -- analyze it to capture function calls that may require
2651 -- finalization actions.
2654 I_Spec
: constant Node_Id
:=
2655 Make_Iterator_Specification
(Sloc
(N
),
2656 Defining_Identifier
=> Relocate_Node
(Id
),
2658 Subtype_Indication
=> Empty
,
2659 Reverse_Present
=> Reverse_Present
(N
));
2660 Scheme
: constant Node_Id
:= Parent
(N
);
2663 Set_Iterator_Specification
(Scheme
, I_Spec
);
2664 Set_Loop_Parameter_Specification
(Scheme
, Empty
);
2665 Analyze_Iterator_Specification
(I_Spec
);
2667 -- In a generic context, analyze the original domain of
2668 -- iteration, for name capture.
2670 if not Expander_Active
then
2674 -- Set kind of loop parameter, which may be used in the
2675 -- subsequent analysis of the condition in a quantified
2678 Set_Ekind
(Id
, E_Loop_Parameter
);
2682 -- Domain of iteration is not a function call, and is side-effect
2686 -- A quantified expression that appears in a pre/post condition
2687 -- is pre-analyzed several times. If the range is given by an
2688 -- attribute reference it is rewritten as a range, and this is
2689 -- done even with expansion disabled. If the type is already set
2690 -- do not reanalyze, because a range with static bounds may be
2691 -- typed Integer by default.
2693 if Nkind
(Parent
(N
)) = N_Quantified_Expression
2694 and then Present
(Etype
(DS
))
2707 -- Some additional checks if we are iterating through a type
2709 if Is_Entity_Name
(DS
)
2710 and then Present
(Entity
(DS
))
2711 and then Is_Type
(Entity
(DS
))
2713 -- The subtype indication may denote the completion of an incomplete
2714 -- type declaration.
2716 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
2717 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
2718 Set_Etype
(DS
, Entity
(DS
));
2721 Check_Predicate_Use
(Entity
(DS
));
2724 -- Error if not discrete type
2726 if not Is_Discrete_Type
(Etype
(DS
)) then
2727 Wrong_Type
(DS
, Any_Discrete
);
2728 Set_Etype
(DS
, Any_Type
);
2731 Check_Controlled_Array_Attribute
(DS
);
2733 if Nkind
(DS
) = N_Subtype_Indication
then
2734 Check_Predicate_Use
(Entity
(Subtype_Mark
(DS
)));
2737 Make_Index
(DS
, N
, In_Iter_Schm
=> True);
2738 Set_Ekind
(Id
, E_Loop_Parameter
);
2740 -- A quantified expression which appears in a pre- or post-condition may
2741 -- be analyzed multiple times. The analysis of the range creates several
2742 -- itypes which reside in different scopes depending on whether the pre-
2743 -- or post-condition has been expanded. Update the type of the loop
2744 -- variable to reflect the proper itype at each stage of analysis.
2747 or else Etype
(Id
) = Any_Type
2749 (Present
(Etype
(Id
))
2750 and then Is_Itype
(Etype
(Id
))
2751 and then Nkind
(Parent
(Loop_Nod
)) = N_Expression_With_Actions
2752 and then Nkind
(Original_Node
(Parent
(Loop_Nod
))) =
2753 N_Quantified_Expression
)
2755 Set_Etype
(Id
, Etype
(DS
));
2758 -- Treat a range as an implicit reference to the type, to inhibit
2759 -- spurious warnings.
2761 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
2762 Set_Is_Known_Valid
(Id
, True);
2764 -- The loop is not a declarative part, so the loop variable must be
2765 -- frozen explicitly. Do not freeze while preanalyzing a quantified
2766 -- expression because the freeze node will not be inserted into the
2767 -- tree due to flag Is_Spec_Expression being set.
2769 if Nkind
(Parent
(N
)) /= N_Quantified_Expression
then
2771 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
2773 if Is_Non_Empty_List
(Flist
) then
2774 Insert_Actions
(N
, Flist
);
2779 -- Case where we have a range or a subtype, get type bounds
2781 if Nkind_In
(DS
, N_Range
, N_Subtype_Indication
)
2782 and then not Error_Posted
(DS
)
2783 and then Etype
(DS
) /= Any_Type
2784 and then Is_Discrete_Type
(Etype
(DS
))
2791 if Nkind
(DS
) = N_Range
then
2792 L
:= Low_Bound
(DS
);
2793 H
:= High_Bound
(DS
);
2796 Type_Low_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
2798 Type_High_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
2801 -- Check for null or possibly null range and issue warning. We
2802 -- suppress such messages in generic templates and instances,
2803 -- because in practice they tend to be dubious in these cases. The
2804 -- check applies as well to rewritten array element loops where a
2805 -- null range may be detected statically.
2807 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> True) = GT
then
2809 -- Suppress the warning if inside a generic template or
2810 -- instance, since in practice they tend to be dubious in these
2811 -- cases since they can result from intended parameterization.
2813 if not Inside_A_Generic
and then not In_Instance
then
2815 -- Specialize msg if invalid values could make the loop
2816 -- non-null after all.
2818 if Compile_Time_Compare
2819 (L
, H
, Assume_Valid
=> False) = GT
2821 -- Since we know the range of the loop is null, set the
2822 -- appropriate flag to remove the loop entirely during
2825 Set_Is_Null_Loop
(Loop_Nod
);
2827 if Comes_From_Source
(N
) then
2829 ("??loop range is null, loop will not execute", DS
);
2832 -- Here is where the loop could execute because of
2833 -- invalid values, so issue appropriate message and in
2834 -- this case we do not set the Is_Null_Loop flag since
2835 -- the loop may execute.
2837 elsif Comes_From_Source
(N
) then
2839 ("??loop range may be null, loop may not execute",
2842 ("??can only execute if invalid values are present",
2847 -- In either case, suppress warnings in the body of the loop,
2848 -- since it is likely that these warnings will be inappropriate
2849 -- if the loop never actually executes, which is likely.
2851 Set_Suppress_Loop_Warnings
(Loop_Nod
);
2853 -- The other case for a warning is a reverse loop where the
2854 -- upper bound is the integer literal zero or one, and the
2855 -- lower bound may exceed this value.
2857 -- For example, we have
2859 -- for J in reverse N .. 1 loop
2861 -- In practice, this is very likely to be a case of reversing
2862 -- the bounds incorrectly in the range.
2864 elsif Reverse_Present
(N
)
2865 and then Nkind
(Original_Node
(H
)) = N_Integer_Literal
2867 (Intval
(Original_Node
(H
)) = Uint_0
2869 Intval
(Original_Node
(H
)) = Uint_1
)
2871 -- Lower bound may in fact be known and known not to exceed
2872 -- upper bound (e.g. reverse 0 .. 1) and that's OK.
2874 if Compile_Time_Known_Value
(L
)
2875 and then Expr_Value
(L
) <= Expr_Value
(H
)
2879 -- Otherwise warning is warranted
2882 Error_Msg_N
("??loop range may be null", DS
);
2883 Error_Msg_N
("\??bounds may be wrong way round", DS
);
2887 -- Check if either bound is known to be outside the range of the
2888 -- loop parameter type, this is e.g. the case of a loop from
2889 -- 20..X where the type is 1..19.
2891 -- Such a loop is dubious since either it raises CE or it executes
2892 -- zero times, and that cannot be useful!
2894 if Etype
(DS
) /= Any_Type
2895 and then not Error_Posted
(DS
)
2896 and then Nkind
(DS
) = N_Subtype_Indication
2897 and then Nkind
(Constraint
(DS
)) = N_Range_Constraint
2900 LLo
: constant Node_Id
:=
2901 Low_Bound
(Range_Expression
(Constraint
(DS
)));
2902 LHi
: constant Node_Id
:=
2903 High_Bound
(Range_Expression
(Constraint
(DS
)));
2905 Bad_Bound
: Node_Id
:= Empty
;
2906 -- Suspicious loop bound
2909 -- At this stage L, H are the bounds of the type, and LLo
2910 -- Lhi are the low bound and high bound of the loop.
2912 if Compile_Time_Compare
(LLo
, L
, Assume_Valid
=> True) = LT
2914 Compile_Time_Compare
(LLo
, H
, Assume_Valid
=> True) = GT
2919 if Compile_Time_Compare
(LHi
, L
, Assume_Valid
=> True) = LT
2921 Compile_Time_Compare
(LHi
, H
, Assume_Valid
=> True) = GT
2926 if Present
(Bad_Bound
) then
2928 ("suspicious loop bound out of range of "
2929 & "loop subtype??", Bad_Bound
);
2931 ("\loop executes zero times or raises "
2932 & "Constraint_Error??", Bad_Bound
);
2937 -- This declare block is about warnings, if we get an exception while
2938 -- testing for warnings, we simply abandon the attempt silently. This
2939 -- most likely occurs as the result of a previous error, but might
2940 -- just be an obscure case we have missed. In either case, not giving
2941 -- the warning is perfectly acceptable.
2944 when others => null;
2948 -- A loop parameter cannot be effectively volatile. This check is
2949 -- peformed only when SPARK_Mode is on as it is not a standard Ada
2950 -- legality check (SPARK RM 7.1.3(6)).
2952 if SPARK_Mode
= On
and then Is_Effectively_Volatile
(Id
) then
2953 Error_Msg_N
("loop parameter cannot be volatile", Id
);
2955 end Analyze_Loop_Parameter_Specification
;
2957 ----------------------------
2958 -- Analyze_Loop_Statement --
2959 ----------------------------
2961 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
2963 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean;
2964 -- Given a loop iteration scheme, determine whether it is an Ada 2012
2965 -- container iteration.
2967 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean;
2968 -- Determine whether loop statement N has been wrapped in a block to
2969 -- capture finalization actions that may be generated for container
2970 -- iterators. Prevents infinite recursion when block is analyzed.
2971 -- Routine is a noop if loop is single statement within source block.
2973 ---------------------------
2974 -- Is_Container_Iterator --
2975 ---------------------------
2977 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean is
2986 elsif Present
(Condition
(Iter
)) then
2989 -- for Def_Id in [reverse] Name loop
2990 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
2992 elsif Present
(Iterator_Specification
(Iter
)) then
2994 Nam
: constant Node_Id
:= Name
(Iterator_Specification
(Iter
));
2998 Nam_Copy
:= New_Copy_Tree
(Nam
);
2999 Set_Parent
(Nam_Copy
, Parent
(Nam
));
3000 Preanalyze_Range
(Nam_Copy
);
3002 -- The only two options here are iteration over a container or
3005 return not Is_Array_Type
(Etype
(Nam_Copy
));
3008 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
3012 LP
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3013 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(LP
);
3017 DS_Copy
:= New_Copy_Tree
(DS
);
3018 Set_Parent
(DS_Copy
, Parent
(DS
));
3019 Preanalyze_Range
(DS_Copy
);
3021 -- Check for a call to Iterate ()
3024 Nkind
(DS_Copy
) = N_Function_Call
3025 and then Needs_Finalization
(Etype
(DS_Copy
));
3028 end Is_Container_Iterator
;
3030 -------------------------
3031 -- Is_Wrapped_In_Block --
3032 -------------------------
3034 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean is
3040 -- Check if current scope is a block that is not a transient block.
3042 if Ekind
(Current_Scope
) /= E_Block
3043 or else No
(Block_Node
(Current_Scope
))
3049 Handled_Statement_Sequence
(Parent
(Block_Node
(Current_Scope
)));
3051 -- Skip leading pragmas that may be introduced for invariant and
3052 -- predicate checks.
3054 Stat
:= First
(Statements
(HSS
));
3055 while Present
(Stat
) and then Nkind
(Stat
) = N_Pragma
loop
3056 Stat
:= Next
(Stat
);
3059 return Stat
= N
and then No
(Next
(Stat
));
3061 end Is_Wrapped_In_Block
;
3063 -- Local declarations
3065 Id
: constant Node_Id
:= Identifier
(N
);
3066 Iter
: constant Node_Id
:= Iteration_Scheme
(N
);
3067 Loc
: constant Source_Ptr
:= Sloc
(N
);
3071 -- Start of processing for Analyze_Loop_Statement
3074 if Present
(Id
) then
3076 -- Make name visible, e.g. for use in exit statements. Loop labels
3077 -- are always considered to be referenced.
3082 -- Guard against serious error (typically, a scope mismatch when
3083 -- semantic analysis is requested) by creating loop entity to
3084 -- continue analysis.
3087 if Total_Errors_Detected
/= 0 then
3088 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3090 raise Program_Error
;
3093 -- Verify that the loop name is hot hidden by an unrelated
3094 -- declaration in an inner scope.
3096 elsif Ekind
(Ent
) /= E_Label
and then Ekind
(Ent
) /= E_Loop
then
3097 Error_Msg_Sloc
:= Sloc
(Ent
);
3098 Error_Msg_N
("implicit label declaration for & is hidden#", Id
);
3100 if Present
(Homonym
(Ent
))
3101 and then Ekind
(Homonym
(Ent
)) = E_Label
3103 Set_Entity
(Id
, Ent
);
3104 Set_Ekind
(Ent
, E_Loop
);
3108 Generate_Reference
(Ent
, N
, ' ');
3109 Generate_Definition
(Ent
);
3111 -- If we found a label, mark its type. If not, ignore it, since it
3112 -- means we have a conflicting declaration, which would already
3113 -- have been diagnosed at declaration time. Set Label_Construct
3114 -- of the implicit label declaration, which is not created by the
3115 -- parser for generic units.
3117 if Ekind
(Ent
) = E_Label
then
3118 Set_Ekind
(Ent
, E_Loop
);
3120 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
3121 Set_Label_Construct
(Parent
(Ent
), N
);
3126 -- Case of no identifier present
3129 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3130 Set_Etype
(Ent
, Standard_Void_Type
);
3131 Set_Parent
(Ent
, N
);
3134 -- Iteration over a container in Ada 2012 involves the creation of a
3135 -- controlled iterator object. Wrap the loop in a block to ensure the
3136 -- timely finalization of the iterator and release of container locks.
3137 -- The same applies to the use of secondary stack when obtaining an
3140 if Ada_Version
>= Ada_2012
3141 and then Is_Container_Iterator
(Iter
)
3142 and then not Is_Wrapped_In_Block
(N
)
3145 Block_Nod
: Node_Id
;
3146 Block_Id
: Entity_Id
;
3150 Make_Block_Statement
(Loc
,
3151 Declarations
=> New_List
,
3152 Handled_Statement_Sequence
=>
3153 Make_Handled_Sequence_Of_Statements
(Loc
,
3154 Statements
=> New_List
(Relocate_Node
(N
))));
3156 Add_Block_Identifier
(Block_Nod
, Block_Id
);
3158 -- The expansion of iterator loops generates an iterator in order
3159 -- to traverse the elements of a container:
3161 -- Iter : <iterator type> := Iterate (Container)'reference;
3163 -- The iterator is controlled and returned on the secondary stack.
3164 -- The analysis of the call to Iterate establishes a transient
3165 -- scope to deal with the secondary stack management, but never
3166 -- really creates a physical block as this would kill the iterator
3167 -- too early (see Wrap_Transient_Declaration). To address this
3168 -- case, mark the generated block as needing secondary stack
3171 Set_Uses_Sec_Stack
(Block_Id
);
3173 Rewrite
(N
, Block_Nod
);
3179 -- Kill current values on entry to loop, since statements in the body of
3180 -- the loop may have been executed before the loop is entered. Similarly
3181 -- we kill values after the loop, since we do not know that the body of
3182 -- the loop was executed.
3184 Kill_Current_Values
;
3186 Analyze_Iteration_Scheme
(Iter
);
3188 -- Check for following case which merits a warning if the type E of is
3189 -- a multi-dimensional array (and no explicit subscript ranges present).
3195 and then Present
(Loop_Parameter_Specification
(Iter
))
3198 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3199 DSD
: constant Node_Id
:=
3200 Original_Node
(Discrete_Subtype_Definition
(LPS
));
3202 if Nkind
(DSD
) = N_Attribute_Reference
3203 and then Attribute_Name
(DSD
) = Name_Range
3204 and then No
(Expressions
(DSD
))
3207 Typ
: constant Entity_Id
:= Etype
(Prefix
(DSD
));
3209 if Is_Array_Type
(Typ
)
3210 and then Number_Dimensions
(Typ
) > 1
3211 and then Nkind
(Parent
(N
)) = N_Loop_Statement
3212 and then Present
(Iteration_Scheme
(Parent
(N
)))
3215 OIter
: constant Node_Id
:=
3216 Iteration_Scheme
(Parent
(N
));
3217 OLPS
: constant Node_Id
:=
3218 Loop_Parameter_Specification
(OIter
);
3219 ODSD
: constant Node_Id
:=
3220 Original_Node
(Discrete_Subtype_Definition
(OLPS
));
3222 if Nkind
(ODSD
) = N_Attribute_Reference
3223 and then Attribute_Name
(ODSD
) = Name_Range
3224 and then No
(Expressions
(ODSD
))
3225 and then Etype
(Prefix
(ODSD
)) = Typ
3227 Error_Msg_Sloc
:= Sloc
(ODSD
);
3229 ("inner range same as outer range#??", DSD
);
3238 -- Analyze the statements of the body except in the case of an Ada 2012
3239 -- iterator with the expander active. In this case the expander will do
3240 -- a rewrite of the loop into a while loop. We will then analyze the
3241 -- loop body when we analyze this while loop.
3243 -- We need to do this delay because if the container is for indefinite
3244 -- types the actual subtype of the components will only be determined
3245 -- when the cursor declaration is analyzed.
3247 -- If the expander is not active, or in SPARK mode, then we want to
3248 -- analyze the loop body now even in the Ada 2012 iterator case, since
3249 -- the rewriting will not be done. Insert the loop variable in the
3250 -- current scope, if not done when analysing the iteration scheme.
3251 -- Set its kind properly to detect improper uses in the loop body.
3254 and then Present
(Iterator_Specification
(Iter
))
3256 if not Expander_Active
then
3258 I_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
3259 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3262 if Scope
(Id
) /= Current_Scope
then
3266 -- In an element iterator, The loop parameter is a variable if
3267 -- the domain of iteration (container or array) is a variable.
3269 if not Of_Present
(I_Spec
)
3270 or else not Is_Variable
(Name
(I_Spec
))
3272 Set_Ekind
(Id
, E_Loop_Parameter
);
3276 Analyze_Statements
(Statements
(N
));
3281 -- Pre-Ada2012 for-loops and while loops.
3283 Analyze_Statements
(Statements
(N
));
3286 -- When the iteration scheme of a loop contains attribute 'Loop_Entry,
3287 -- the loop is transformed into a conditional block. Retrieve the loop.
3291 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
3292 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
3295 -- Finish up processing for the loop. We kill all current values, since
3296 -- in general we don't know if the statements in the loop have been
3297 -- executed. We could do a bit better than this with a loop that we
3298 -- know will execute at least once, but it's not worth the trouble and
3299 -- the front end is not in the business of flow tracing.
3301 Process_End_Label
(Stmt
, 'e', Ent
);
3303 Kill_Current_Values
;
3305 -- Check for infinite loop. Skip check for generated code, since it
3306 -- justs waste time and makes debugging the routine called harder.
3308 -- Note that we have to wait till the body of the loop is fully analyzed
3309 -- before making this call, since Check_Infinite_Loop_Warning relies on
3310 -- being able to use semantic visibility information to find references.
3312 if Comes_From_Source
(Stmt
) then
3313 Check_Infinite_Loop_Warning
(Stmt
);
3316 -- Code after loop is unreachable if the loop has no WHILE or FOR and
3317 -- contains no EXIT statements within the body of the loop.
3319 if No
(Iter
) and then not Has_Exit
(Ent
) then
3320 Check_Unreachable_Code
(Stmt
);
3322 end Analyze_Loop_Statement
;
3324 ----------------------------
3325 -- Analyze_Null_Statement --
3326 ----------------------------
3328 -- Note: the semantics of the null statement is implemented by a single
3329 -- null statement, too bad everything isn't as simple as this.
3331 procedure Analyze_Null_Statement
(N
: Node_Id
) is
3332 pragma Warnings
(Off
, N
);
3335 end Analyze_Null_Statement
;
3337 ------------------------
3338 -- Analyze_Statements --
3339 ------------------------
3341 procedure Analyze_Statements
(L
: List_Id
) is
3346 -- The labels declared in the statement list are reachable from
3347 -- statements in the list. We do this as a prepass so that any goto
3348 -- statement will be properly flagged if its target is not reachable.
3349 -- This is not required, but is nice behavior.
3352 while Present
(S
) loop
3353 if Nkind
(S
) = N_Label
then
3354 Analyze
(Identifier
(S
));
3355 Lab
:= Entity
(Identifier
(S
));
3357 -- If we found a label mark it as reachable
3359 if Ekind
(Lab
) = E_Label
then
3360 Generate_Definition
(Lab
);
3361 Set_Reachable
(Lab
);
3363 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
3364 Set_Label_Construct
(Parent
(Lab
), S
);
3367 -- If we failed to find a label, it means the implicit declaration
3368 -- of the label was hidden. A for-loop parameter can do this to
3369 -- a label with the same name inside the loop, since the implicit
3370 -- label declaration is in the innermost enclosing body or block
3374 Error_Msg_Sloc
:= Sloc
(Lab
);
3376 ("implicit label declaration for & is hidden#",
3384 -- Perform semantic analysis on all statements
3386 Conditional_Statements_Begin
;
3389 while Present
(S
) loop
3392 -- Remove dimension in all statements
3394 Remove_Dimension_In_Statement
(S
);
3398 Conditional_Statements_End
;
3400 -- Make labels unreachable. Visibility is not sufficient, because labels
3401 -- in one if-branch for example are not reachable from the other branch,
3402 -- even though their declarations are in the enclosing declarative part.
3405 while Present
(S
) loop
3406 if Nkind
(S
) = N_Label
then
3407 Set_Reachable
(Entity
(Identifier
(S
)), False);
3412 end Analyze_Statements
;
3414 ----------------------------
3415 -- Check_Unreachable_Code --
3416 ----------------------------
3418 procedure Check_Unreachable_Code
(N
: Node_Id
) is
3419 Error_Node
: Node_Id
;
3423 if Is_List_Member
(N
) and then Comes_From_Source
(N
) then
3428 Nxt
:= Original_Node
(Next
(N
));
3430 -- Skip past pragmas
3432 while Nkind
(Nxt
) = N_Pragma
loop
3433 Nxt
:= Original_Node
(Next
(Nxt
));
3436 -- If a label follows us, then we never have dead code, since
3437 -- someone could branch to the label, so we just ignore it, unless
3438 -- we are in formal mode where goto statements are not allowed.
3440 if Nkind
(Nxt
) = N_Label
3441 and then not Restriction_Check_Required
(SPARK_05
)
3445 -- Otherwise see if we have a real statement following us
3448 and then Comes_From_Source
(Nxt
)
3449 and then Is_Statement
(Nxt
)
3451 -- Special very annoying exception. If we have a return that
3452 -- follows a raise, then we allow it without a warning, since
3453 -- the Ada RM annoyingly requires a useless return here.
3455 if Nkind
(Original_Node
(N
)) /= N_Raise_Statement
3456 or else Nkind
(Nxt
) /= N_Simple_Return_Statement
3458 -- The rather strange shenanigans with the warning message
3459 -- here reflects the fact that Kill_Dead_Code is very good
3460 -- at removing warnings in deleted code, and this is one
3461 -- warning we would prefer NOT to have removed.
3465 -- If we have unreachable code, analyze and remove the
3466 -- unreachable code, since it is useless and we don't
3467 -- want to generate junk warnings.
3469 -- We skip this step if we are not in code generation mode
3470 -- or CodePeer mode.
3472 -- This is the one case where we remove dead code in the
3473 -- semantics as opposed to the expander, and we do not want
3474 -- to remove code if we are not in code generation mode,
3475 -- since this messes up the ASIS trees or loses useful
3476 -- information in the CodePeer tree.
3478 -- Note that one might react by moving the whole circuit to
3479 -- exp_ch5, but then we lose the warning in -gnatc mode.
3481 if Operating_Mode
= Generate_Code
3482 and then not CodePeer_Mode
3487 -- Quit deleting when we have nothing more to delete
3488 -- or if we hit a label (since someone could transfer
3489 -- control to a label, so we should not delete it).
3491 exit when No
(Nxt
) or else Nkind
(Nxt
) = N_Label
;
3493 -- Statement/declaration is to be deleted
3497 Kill_Dead_Code
(Nxt
);
3501 -- Now issue the warning (or error in formal mode)
3503 if Restriction_Check_Required
(SPARK_05
) then
3504 Check_SPARK_05_Restriction
3505 ("unreachable code is not allowed", Error_Node
);
3507 Error_Msg
("??unreachable code!", Sloc
(Error_Node
));
3511 -- If the unconditional transfer of control instruction is the
3512 -- last statement of a sequence, then see if our parent is one of
3513 -- the constructs for which we count unblocked exits, and if so,
3514 -- adjust the count.
3519 -- Statements in THEN part or ELSE part of IF statement
3521 if Nkind
(P
) = N_If_Statement
then
3524 -- Statements in ELSIF part of an IF statement
3526 elsif Nkind
(P
) = N_Elsif_Part
then
3528 pragma Assert
(Nkind
(P
) = N_If_Statement
);
3530 -- Statements in CASE statement alternative
3532 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
3534 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
3536 -- Statements in body of block
3538 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
3539 and then Nkind
(Parent
(P
)) = N_Block_Statement
3541 -- The original loop is now placed inside a block statement
3542 -- due to the expansion of attribute 'Loop_Entry. Return as
3543 -- this is not a "real" block for the purposes of exit
3546 if Nkind
(N
) = N_Loop_Statement
3547 and then Subject_To_Loop_Entry_Attributes
(N
)
3552 -- Statements in exception handler in a block
3554 elsif Nkind
(P
) = N_Exception_Handler
3555 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
3556 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
3560 -- None of these cases, so return
3566 -- This was one of the cases we are looking for (i.e. the
3567 -- parent construct was IF, CASE or block) so decrement count.
3569 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
3573 end Check_Unreachable_Code
;
3575 ----------------------
3576 -- Preanalyze_Range --
3577 ----------------------
3579 procedure Preanalyze_Range
(R_Copy
: Node_Id
) is
3580 Save_Analysis
: constant Boolean := Full_Analysis
;
3584 Full_Analysis
:= False;
3585 Expander_Mode_Save_And_Set
(False);
3589 if Nkind
(R_Copy
) in N_Subexpr
and then Is_Overloaded
(R_Copy
) then
3591 -- Apply preference rules for range of predefined integer types, or
3592 -- diagnose true ambiguity.
3597 Found
: Entity_Id
:= Empty
;
3600 Get_First_Interp
(R_Copy
, I
, It
);
3601 while Present
(It
.Typ
) loop
3602 if Is_Discrete_Type
(It
.Typ
) then
3606 if Scope
(Found
) = Standard_Standard
then
3609 elsif Scope
(It
.Typ
) = Standard_Standard
then
3613 -- Both of them are user-defined
3616 ("ambiguous bounds in range of iteration", R_Copy
);
3617 Error_Msg_N
("\possible interpretations:", R_Copy
);
3618 Error_Msg_NE
("\\} ", R_Copy
, Found
);
3619 Error_Msg_NE
("\\} ", R_Copy
, It
.Typ
);
3625 Get_Next_Interp
(I
, It
);
3630 -- Subtype mark in iteration scheme
3632 if Is_Entity_Name
(R_Copy
) and then Is_Type
(Entity
(R_Copy
)) then
3635 -- Expression in range, or Ada 2012 iterator
3637 elsif Nkind
(R_Copy
) in N_Subexpr
then
3639 Typ
:= Etype
(R_Copy
);
3641 if Is_Discrete_Type
(Typ
) then
3644 -- Check that the resulting object is an iterable container
3646 elsif Has_Aspect
(Typ
, Aspect_Iterator_Element
)
3647 or else Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
3648 or else Has_Aspect
(Typ
, Aspect_Variable_Indexing
)
3652 -- The expression may yield an implicit reference to an iterable
3653 -- container. Insert explicit dereference so that proper type is
3654 -- visible in the loop.
3656 elsif Has_Implicit_Dereference
(Etype
(R_Copy
)) then
3661 Disc
:= First_Discriminant
(Typ
);
3662 while Present
(Disc
) loop
3663 if Has_Implicit_Dereference
(Disc
) then
3664 Build_Explicit_Dereference
(R_Copy
, Disc
);
3668 Next_Discriminant
(Disc
);
3675 Expander_Mode_Restore
;
3676 Full_Analysis
:= Save_Analysis
;
3677 end Preanalyze_Range
;