1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2017, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Aspects
; use Aspects
;
27 with Atree
; use Atree
;
28 with Checks
; use Checks
;
29 with Einfo
; use Einfo
;
30 with Errout
; use Errout
;
31 with Expander
; use Expander
;
32 with Exp_Ch6
; use Exp_Ch6
;
33 with Exp_Util
; use Exp_Util
;
34 with Freeze
; use Freeze
;
35 with Ghost
; use Ghost
;
37 with Lib
.Xref
; use Lib
.Xref
;
38 with Namet
; use Namet
;
39 with Nlists
; use Nlists
;
40 with Nmake
; use Nmake
;
42 with Restrict
; use Restrict
;
43 with Rident
; use Rident
;
45 with Sem_Aux
; use Sem_Aux
;
46 with Sem_Case
; use Sem_Case
;
47 with Sem_Ch3
; use Sem_Ch3
;
48 with Sem_Ch6
; use Sem_Ch6
;
49 with Sem_Ch8
; use Sem_Ch8
;
50 with Sem_Dim
; use Sem_Dim
;
51 with Sem_Disp
; use Sem_Disp
;
52 with Sem_Elab
; use Sem_Elab
;
53 with Sem_Eval
; use Sem_Eval
;
54 with Sem_Res
; use Sem_Res
;
55 with Sem_Type
; use Sem_Type
;
56 with Sem_Util
; use Sem_Util
;
57 with Sem_Warn
; use Sem_Warn
;
58 with Snames
; use Snames
;
59 with Stand
; use Stand
;
60 with Sinfo
; use Sinfo
;
61 with Targparm
; use Targparm
;
62 with Tbuild
; use Tbuild
;
63 with Uintp
; use Uintp
;
65 package body Sem_Ch5
is
67 Current_Assignment
: Node_Id
:= Empty
;
68 -- This variable holds the node for an assignment that contains target
69 -- names. The corresponding flag has been set by the parser, and when
70 -- set the analysis of the RHS must be done with all expansion disabled,
71 -- because the assignment is reanalyzed after expansion has replaced all
72 -- occurrences of the target name appropriately.
74 Unblocked_Exit_Count
: Nat
:= 0;
75 -- This variable is used when processing if statements, case statements,
76 -- and block statements. It counts the number of exit points that are not
77 -- blocked by unconditional transfer instructions: for IF and CASE, these
78 -- are the branches of the conditional; for a block, they are the statement
79 -- sequence of the block, and the statement sequences of any exception
80 -- handlers that are part of the block. When processing is complete, if
81 -- this count is zero, it means that control cannot fall through the IF,
82 -- CASE or block statement. This is used for the generation of warning
83 -- messages. This variable is recursively saved on entry to processing the
84 -- construct, and restored on exit.
86 procedure Preanalyze_Range
(R_Copy
: Node_Id
);
87 -- Determine expected type of range or domain of iteration of Ada 2012
88 -- loop by analyzing separate copy. Do the analysis and resolution of the
89 -- copy of the bound(s) with expansion disabled, to prevent the generation
90 -- of finalization actions. This prevents memory leaks when the bounds
91 -- contain calls to functions returning controlled arrays or when the
92 -- domain of iteration is a container.
94 ------------------------
95 -- Analyze_Assignment --
96 ------------------------
98 -- WARNING: This routine manages Ghost regions. Return statements must be
99 -- replaced by gotos which jump to the end of the routine and restore the
102 procedure Analyze_Assignment
(N
: Node_Id
) is
103 Lhs
: constant Node_Id
:= Name
(N
);
104 Rhs
: Node_Id
:= Expression
(N
);
106 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
);
107 -- N is the node for the left hand side of an assignment, and it is not
108 -- a variable. This routine issues an appropriate diagnostic.
111 -- This is called to kill current value settings of a simple variable
112 -- on the left hand side. We call it if we find any error in analyzing
113 -- the assignment, and at the end of processing before setting any new
114 -- current values in place.
116 procedure Set_Assignment_Type
118 Opnd_Type
: in out Entity_Id
);
119 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
120 -- nominal subtype. This procedure is used to deal with cases where the
121 -- nominal subtype must be replaced by the actual subtype.
123 procedure Transform_BIP_Assignment
(Typ
: Entity_Id
);
124 function Should_Transform_BIP_Assignment
125 (Typ
: Entity_Id
) return Boolean;
126 -- If the right-hand side of an assignment statement is a build-in-place
127 -- call we cannot build in place, so we insert a temp initialized with
128 -- the call, and transform the assignment statement to copy the temp.
129 -- Transform_BIP_Assignment does the tranformation, and
130 -- Should_Transform_BIP_Assignment determines whether we should.
131 -- The same goes for qualified expressions and conversions whose
132 -- operand is such a call.
134 -- This is only for nonlimited types; assignment statements are illegal
135 -- for limited types, but are generated internally for aggregates and
136 -- init procs. These limited-type are not really assignment statements
137 -- -- conceptually, they are initializations, so should not be
140 -- Similarly, for nonlimited types, aggregates and init procs generate
141 -- assignment statements that are really initializations. These are
142 -- marked No_Ctrl_Actions.
144 -------------------------------
145 -- Diagnose_Non_Variable_Lhs --
146 -------------------------------
148 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
150 -- Not worth posting another error if left hand side already flagged
151 -- as being illegal in some respect.
153 if Error_Posted
(N
) then
156 -- Some special bad cases of entity names
158 elsif Is_Entity_Name
(N
) then
160 Ent
: constant Entity_Id
:= Entity
(N
);
163 if Ekind
(Ent
) = E_In_Parameter
then
165 ("assignment to IN mode parameter not allowed", N
);
168 -- Renamings of protected private components are turned into
169 -- constants when compiling a protected function. In the case
170 -- of single protected types, the private component appears
173 elsif (Is_Prival
(Ent
)
175 (Ekind
(Current_Scope
) = E_Function
176 or else Ekind
(Enclosing_Dynamic_Scope
177 (Current_Scope
)) = E_Function
))
179 (Ekind
(Ent
) = E_Component
180 and then Is_Protected_Type
(Scope
(Ent
)))
183 ("protected function cannot modify protected object", N
);
186 elsif Ekind
(Ent
) = E_Loop_Parameter
then
187 Error_Msg_N
("assignment to loop parameter not allowed", N
);
192 -- For indexed components, test prefix if it is in array. We do not
193 -- want to recurse for cases where the prefix is a pointer, since we
194 -- may get a message confusing the pointer and what it references.
196 elsif Nkind
(N
) = N_Indexed_Component
197 and then Is_Array_Type
(Etype
(Prefix
(N
)))
199 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
202 -- Another special case for assignment to discriminant
204 elsif Nkind
(N
) = N_Selected_Component
then
205 if Present
(Entity
(Selector_Name
(N
)))
206 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
208 Error_Msg_N
("assignment to discriminant not allowed", N
);
211 -- For selection from record, diagnose prefix, but note that again
212 -- we only do this for a record, not e.g. for a pointer.
214 elsif Is_Record_Type
(Etype
(Prefix
(N
))) then
215 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
220 -- If we fall through, we have no special message to issue
222 Error_Msg_N
("left hand side of assignment must be a variable", N
);
223 end Diagnose_Non_Variable_Lhs
;
229 procedure Kill_Lhs
is
231 if Is_Entity_Name
(Lhs
) then
233 Ent
: constant Entity_Id
:= Entity
(Lhs
);
235 if Present
(Ent
) then
236 Kill_Current_Values
(Ent
);
242 -------------------------
243 -- Set_Assignment_Type --
244 -------------------------
246 procedure Set_Assignment_Type
248 Opnd_Type
: in out Entity_Id
)
253 Require_Entity
(Opnd
);
255 -- If the assignment operand is an in-out or out parameter, then we
256 -- get the actual subtype (needed for the unconstrained case). If the
257 -- operand is the actual in an entry declaration, then within the
258 -- accept statement it is replaced with a local renaming, which may
259 -- also have an actual subtype.
261 if Is_Entity_Name
(Opnd
)
262 and then (Ekind
(Entity
(Opnd
)) = E_Out_Parameter
263 or else Ekind_In
(Entity
(Opnd
),
265 E_Generic_In_Out_Parameter
)
267 (Ekind
(Entity
(Opnd
)) = E_Variable
268 and then Nkind
(Parent
(Entity
(Opnd
))) =
269 N_Object_Renaming_Declaration
270 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
273 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
275 -- If assignment operand is a component reference, then we get the
276 -- actual subtype of the component for the unconstrained case.
278 elsif Nkind_In
(Opnd
, N_Selected_Component
, N_Explicit_Dereference
)
279 and then not Is_Unchecked_Union
(Opnd_Type
)
281 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
283 if Present
(Decl
) then
284 Insert_Action
(N
, Decl
);
285 Mark_Rewrite_Insertion
(Decl
);
287 Opnd_Type
:= Defining_Identifier
(Decl
);
288 Set_Etype
(Opnd
, Opnd_Type
);
289 Freeze_Itype
(Opnd_Type
, N
);
291 elsif Is_Constrained
(Etype
(Opnd
)) then
292 Opnd_Type
:= Etype
(Opnd
);
295 -- For slice, use the constrained subtype created for the slice
297 elsif Nkind
(Opnd
) = N_Slice
then
298 Opnd_Type
:= Etype
(Opnd
);
300 end Set_Assignment_Type
;
302 -------------------------------------
303 -- Should_Transform_BIP_Assignment --
304 -------------------------------------
306 function Should_Transform_BIP_Assignment
307 (Typ
: Entity_Id
) return Boolean
313 and then not Is_Limited_View
(Typ
)
314 and then Is_Build_In_Place_Result_Type
(Typ
)
315 and then not No_Ctrl_Actions
(N
)
317 -- This function is called early, before name resolution is
318 -- complete, so we have to deal with things that might turn into
319 -- function calls later. N_Function_Call and N_Op nodes are the
320 -- obvious case. An N_Identifier or N_Expanded_Name is a
321 -- parameterless function call if it denotes a function.
322 -- Finally, an attribute reference can be a function call.
324 case Nkind
(Unqual_Conv
(Rhs
)) is
333 case Ekind
(Entity
(Unqual_Conv
(Rhs
))) is
343 when N_Attribute_Reference
=>
344 Result
:= Attribute_Name
(Unqual_Conv
(Rhs
)) = Name_Input
;
345 -- T'Input will turn into a call whose result type is T
355 end Should_Transform_BIP_Assignment
;
357 ------------------------------
358 -- Transform_BIP_Assignment --
359 ------------------------------
361 procedure Transform_BIP_Assignment
(Typ
: Entity_Id
) is
363 -- Tranform "X : [constant] T := F (...);" into:
365 -- Temp : constant T := F (...);
368 Loc
: constant Source_Ptr
:= Sloc
(N
);
369 Def_Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'Y', Rhs
);
370 Obj_Decl
: constant Node_Id
:=
371 Make_Object_Declaration
(Loc
,
372 Defining_Identifier
=> Def_Id
,
373 Constant_Present
=> True,
374 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
),
376 Has_Init_Expression
=> True);
379 Set_Etype
(Def_Id
, Typ
);
380 Set_Expression
(N
, New_Occurrence_Of
(Def_Id
, Loc
));
382 -- At this point, Rhs is no longer equal to Expression (N), so:
384 Rhs
:= Expression
(N
);
386 Insert_Action
(N
, Obj_Decl
);
387 end Transform_BIP_Assignment
;
394 Save_Full_Analysis
: Boolean := False;
395 -- Force initialization to facilitate static analysis
397 Saved_GM
: constant Ghost_Mode_Type
:= Ghost_Mode
;
398 -- Save the Ghost mode to restore on exit
400 -- Start of processing for Analyze_Assignment
403 Mark_Coextensions
(N
, Rhs
);
405 -- Preserve relevant elaboration-related attributes of the context which
406 -- are no longer available or very expensive to recompute once analysis,
407 -- resolution, and expansion are over.
409 Mark_Elaboration_Attributes
414 -- Analyze the target of the assignment first in case the expression
415 -- contains references to Ghost entities. The checks that verify the
416 -- proper use of a Ghost entity need to know the enclosing context.
420 -- An assignment statement is Ghost when the left hand side denotes a
421 -- Ghost entity. Set the mode now to ensure that any nodes generated
422 -- during analysis and expansion are properly marked as Ghost.
424 if Has_Target_Names
(N
) then
425 Current_Assignment
:= N
;
426 Expander_Mode_Save_And_Set
(False);
427 Save_Full_Analysis
:= Full_Analysis
;
428 Full_Analysis
:= False;
430 Current_Assignment
:= Empty
;
433 Mark_And_Set_Ghost_Assignment
(N
);
436 -- Ensure that we never do an assignment on a variable marked as
437 -- Is_Safe_To_Reevaluate.
440 (not Is_Entity_Name
(Lhs
)
441 or else Ekind
(Entity
(Lhs
)) /= E_Variable
442 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
444 -- Start type analysis for assignment
448 -- In the most general case, both Lhs and Rhs can be overloaded, and we
449 -- must compute the intersection of the possible types on each side.
451 if Is_Overloaded
(Lhs
) then
458 Get_First_Interp
(Lhs
, I
, It
);
460 while Present
(It
.Typ
) loop
462 -- An indexed component with generalized indexing is always
463 -- overloaded with the corresponding dereference. Discard the
464 -- interpretation that yields a reference type, which is not
467 if Nkind
(Lhs
) = N_Indexed_Component
468 and then Present
(Generalized_Indexing
(Lhs
))
469 and then Has_Implicit_Dereference
(It
.Typ
)
473 -- This may be a call to a parameterless function through an
474 -- implicit dereference, so discard interpretation as well.
476 elsif Is_Entity_Name
(Lhs
)
477 and then Has_Implicit_Dereference
(It
.Typ
)
481 elsif Has_Compatible_Type
(Rhs
, It
.Typ
) then
482 if T1
= Any_Type
then
485 -- An explicit dereference is overloaded if the prefix
486 -- is. Try to remove the ambiguity on the prefix, the
487 -- error will be posted there if the ambiguity is real.
489 if Nkind
(Lhs
) = N_Explicit_Dereference
then
492 PI1
: Interp_Index
:= 0;
498 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
500 while Present
(PIt
.Typ
) loop
501 if Is_Access_Type
(PIt
.Typ
)
502 and then Has_Compatible_Type
503 (Rhs
, Designated_Type
(PIt
.Typ
))
507 Disambiguate
(Prefix
(Lhs
),
510 if PIt
= No_Interp
then
512 ("ambiguous left-hand side in "
513 & "assignment", Lhs
);
516 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
526 Get_Next_Interp
(PI
, PIt
);
532 ("ambiguous left-hand side in assignment", Lhs
);
538 Get_Next_Interp
(I
, It
);
542 if T1
= Any_Type
then
544 ("no valid types for left-hand side for assignment", Lhs
);
550 -- Deal with build-in-place calls for nonlimited types. We don't do this
551 -- later, because resolving the rhs tranforms it incorrectly for build-
554 if Should_Transform_BIP_Assignment
(Typ
=> T1
) then
555 Transform_BIP_Assignment
(Typ
=> T1
);
558 pragma Assert
(not Should_Transform_BIP_Assignment
(Typ
=> T1
));
560 -- The resulting assignment type is T1, so now we will resolve the left
561 -- hand side of the assignment using this determined type.
565 -- Cases where Lhs is not a variable. In an instance or an inlined body
566 -- no need for further check because assignment was legal in template.
568 if In_Inlined_Body
then
571 elsif not Is_Variable
(Lhs
) then
573 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
581 if Ada_Version
>= Ada_2005
then
583 -- Handle chains of renamings
586 while Nkind
(Ent
) in N_Has_Entity
587 and then Present
(Entity
(Ent
))
588 and then Present
(Renamed_Object
(Entity
(Ent
)))
590 Ent
:= Renamed_Object
(Entity
(Ent
));
593 if (Nkind
(Ent
) = N_Attribute_Reference
594 and then Attribute_Name
(Ent
) = Name_Priority
)
596 -- Renamings of the attribute Priority applied to protected
597 -- objects have been previously expanded into calls to the
598 -- Get_Ceiling run-time subprogram.
600 or else Is_Expanded_Priority_Attribute
(Ent
)
602 -- The enclosing subprogram cannot be a protected function
605 while not (Is_Subprogram
(S
)
606 and then Convention
(S
) = Convention_Protected
)
607 and then S
/= Standard_Standard
612 if Ekind
(S
) = E_Function
613 and then Convention
(S
) = Convention_Protected
616 ("protected function cannot modify protected object",
620 -- Changes of the ceiling priority of the protected object
621 -- are only effective if the Ceiling_Locking policy is in
622 -- effect (AARM D.5.2 (5/2)).
624 if Locking_Policy
/= 'C' then
626 ("assignment to the attribute PRIORITY has no effect??",
629 ("\since no Locking_Policy has been specified??", Lhs
);
637 Diagnose_Non_Variable_Lhs
(Lhs
);
640 -- Error of assigning to limited type. We do however allow this in
641 -- certain cases where the front end generates the assignments.
643 elsif Is_Limited_Type
(T1
)
644 and then not Assignment_OK
(Lhs
)
645 and then not Assignment_OK
(Original_Node
(Lhs
))
647 -- CPP constructors can only be called in declarations
649 if Is_CPP_Constructor_Call
(Rhs
) then
650 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
653 ("left hand of assignment must not be limited type", Lhs
);
654 Explain_Limited_Type
(T1
, Lhs
);
659 -- A class-wide type may be a limited view. This illegal case is not
660 -- caught by previous checks.
662 elsif Ekind
(T1
) = E_Class_Wide_Type
and then From_Limited_With
(T1
) then
663 Error_Msg_NE
("invalid use of limited view of&", Lhs
, T1
);
666 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
667 -- abstract. This is only checked when the assignment Comes_From_Source,
668 -- because in some cases the expander generates such assignments (such
669 -- in the _assign operation for an abstract type).
671 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
673 ("target of assignment operation must not be abstract", Lhs
);
676 -- Resolution may have updated the subtype, in case the left-hand side
677 -- is a private protected component. Use the correct subtype to avoid
678 -- scoping issues in the back-end.
682 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
683 -- type. For example:
687 -- type Acc is access P.T;
690 -- with Pkg; use Acc;
691 -- procedure Example is
694 -- A.all := B.all; -- ERROR
697 if Nkind
(Lhs
) = N_Explicit_Dereference
698 and then Ekind
(T1
) = E_Incomplete_Type
700 Error_Msg_N
("invalid use of incomplete type", Lhs
);
705 -- Now we can complete the resolution of the right hand side
707 Set_Assignment_Type
(Lhs
, T1
);
709 -- If the target of the assignment is an entity of a mutable type and
710 -- the expression is a conditional expression, its alternatives can be
711 -- of different subtypes of the nominal type of the LHS, so they must be
712 -- resolved with the base type, given that their subtype may differ from
713 -- that of the target mutable object.
715 if Is_Entity_Name
(Lhs
)
716 and then Ekind_In
(Entity
(Lhs
), E_In_Out_Parameter
,
719 and then Is_Composite_Type
(T1
)
720 and then not Is_Constrained
(Etype
(Entity
(Lhs
)))
721 and then Nkind_In
(Rhs
, N_If_Expression
, N_Case_Expression
)
723 Resolve
(Rhs
, Base_Type
(T1
));
729 -- This is the point at which we check for an unset reference
731 Check_Unset_Reference
(Rhs
);
732 Check_Unprotected_Access
(Lhs
, Rhs
);
734 -- Remaining steps are skipped if Rhs was syntactically in error
743 if not Covers
(T1
, T2
) then
744 Wrong_Type
(Rhs
, Etype
(Lhs
));
749 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
750 -- types, use the non-limited view if available
752 if Nkind
(Rhs
) = N_Explicit_Dereference
753 and then Is_Tagged_Type
(T2
)
754 and then Has_Non_Limited_View
(T2
)
756 T2
:= Non_Limited_View
(T2
);
759 Set_Assignment_Type
(Rhs
, T2
);
761 if Total_Errors_Detected
/= 0 then
771 if T1
= Any_Type
or else T2
= Any_Type
then
776 -- If the rhs is class-wide or dynamically tagged, then require the lhs
777 -- to be class-wide. The case where the rhs is a dynamically tagged call
778 -- to a dispatching operation with a controlling access result is
779 -- excluded from this check, since the target has an access type (and
780 -- no tag propagation occurs in that case).
782 if (Is_Class_Wide_Type
(T2
)
783 or else (Is_Dynamically_Tagged
(Rhs
)
784 and then not Is_Access_Type
(T1
)))
785 and then not Is_Class_Wide_Type
(T1
)
787 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
789 elsif Is_Class_Wide_Type
(T1
)
790 and then not Is_Class_Wide_Type
(T2
)
791 and then not Is_Tag_Indeterminate
(Rhs
)
792 and then not Is_Dynamically_Tagged
(Rhs
)
794 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
797 -- Propagate the tag from a class-wide target to the rhs when the rhs
798 -- is a tag-indeterminate call.
800 if Is_Tag_Indeterminate
(Rhs
) then
801 if Is_Class_Wide_Type
(T1
) then
802 Propagate_Tag
(Lhs
, Rhs
);
804 elsif Nkind
(Rhs
) = N_Function_Call
805 and then Is_Entity_Name
(Name
(Rhs
))
806 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
809 ("call to abstract function must be dispatching", Name
(Rhs
));
811 elsif Nkind
(Rhs
) = N_Qualified_Expression
812 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
813 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
815 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
818 ("call to abstract function must be dispatching",
819 Name
(Expression
(Rhs
)));
823 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
824 -- apply an implicit conversion of the rhs to that type to force
825 -- appropriate static and run-time accessibility checks. This applies
826 -- as well to anonymous access-to-subprogram types that are component
827 -- subtypes or formal parameters.
829 if Ada_Version
>= Ada_2005
and then Is_Access_Type
(T1
) then
830 if Is_Local_Anonymous_Access
(T1
)
831 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
833 -- Handle assignment to an Ada 2012 stand-alone object
834 -- of an anonymous access type.
836 or else (Ekind
(T1
) = E_Anonymous_Access_Type
837 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
838 N_Object_Declaration
)
841 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
842 Analyze_And_Resolve
(Rhs
, T1
);
846 -- Ada 2005 (AI-231): Assignment to not null variable
848 if Ada_Version
>= Ada_2005
849 and then Can_Never_Be_Null
(T1
)
850 and then not Assignment_OK
(Lhs
)
852 -- Case where we know the right hand side is null
854 if Known_Null
(Rhs
) then
855 Apply_Compile_Time_Constraint_Error
858 "(Ada 2005) null not allowed in null-excluding objects??",
859 Reason
=> CE_Null_Not_Allowed
);
861 -- We still mark this as a possible modification, that's necessary
862 -- to reset Is_True_Constant, and desirable for xref purposes.
864 Note_Possible_Modification
(Lhs
, Sure
=> True);
867 -- If we know the right hand side is non-null, then we convert to the
868 -- target type, since we don't need a run time check in that case.
870 elsif not Can_Never_Be_Null
(T2
) then
871 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
872 Analyze_And_Resolve
(Rhs
, T1
);
876 if Is_Scalar_Type
(T1
) then
877 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
879 -- For array types, verify that lengths match. If the right hand side
880 -- is a function call that has been inlined, the assignment has been
881 -- rewritten as a block, and the constraint check will be applied to the
882 -- assignment within the block.
884 elsif Is_Array_Type
(T1
)
885 and then (Nkind
(Rhs
) /= N_Type_Conversion
886 or else Is_Constrained
(Etype
(Rhs
)))
887 and then (Nkind
(Rhs
) /= N_Function_Call
888 or else Nkind
(N
) /= N_Block_Statement
)
890 -- Assignment verifies that the length of the Lsh and Rhs are equal,
891 -- but of course the indexes do not have to match. If the right-hand
892 -- side is a type conversion to an unconstrained type, a length check
893 -- is performed on the expression itself during expansion. In rare
894 -- cases, the redundant length check is computed on an index type
895 -- with a different representation, triggering incorrect code in the
898 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
901 -- Discriminant checks are applied in the course of expansion
906 -- Note: modifications of the Lhs may only be recorded after
907 -- checks have been applied.
909 Note_Possible_Modification
(Lhs
, Sure
=> True);
911 -- ??? a real accessibility check is needed when ???
913 -- Post warning for redundant assignment or variable to itself
915 if Warn_On_Redundant_Constructs
917 -- We only warn for source constructs
919 and then Comes_From_Source
(N
)
921 -- Where the object is the same on both sides
923 and then Same_Object
(Lhs
, Original_Node
(Rhs
))
925 -- But exclude the case where the right side was an operation that
926 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
927 -- don't want to warn in such a case, since it is reasonable to write
928 -- such expressions especially when K is defined symbolically in some
931 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
933 if Nkind
(Lhs
) in N_Has_Entity
then
934 Error_Msg_NE
-- CODEFIX
935 ("?r?useless assignment of & to itself!", N
, Entity
(Lhs
));
937 Error_Msg_N
-- CODEFIX
938 ("?r?useless assignment of object to itself!", N
);
942 -- Check for non-allowed composite assignment
944 if not Support_Composite_Assign_On_Target
945 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
946 and then (not Has_Size_Clause
(T1
) or else Esize
(T1
) > 64)
948 Error_Msg_CRT
("composite assignment", N
);
951 -- Save the scenario for later examination by the ABE Processing phase
953 Record_Elaboration_Scenario
(N
);
955 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
956 -- assignment is a source assignment in the extended main source unit.
957 -- We are not interested in any reference information outside this
958 -- context, or in compiler generated assignment statements.
960 if Comes_From_Source
(N
)
961 and then In_Extended_Main_Source_Unit
(Lhs
)
963 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
966 -- RM 7.3.2 (12/3): An assignment to a view conversion (from a type to
967 -- one of its ancestors) requires an invariant check. Apply check only
968 -- if expression comes from source, otherwise it will be applied when
969 -- value is assigned to source entity. This is not done in GNATprove
970 -- mode, as GNATprove handles invariant checks itself.
972 if Nkind
(Lhs
) = N_Type_Conversion
973 and then Has_Invariants
(Etype
(Expression
(Lhs
)))
974 and then Comes_From_Source
(Expression
(Lhs
))
975 and then not GNATprove_Mode
977 Insert_After
(N
, Make_Invariant_Call
(Expression
(Lhs
)));
980 -- Final step. If left side is an entity, then we may be able to reset
981 -- the current tracked values to new safe values. We only have something
982 -- to do if the left side is an entity name, and expansion has not
983 -- modified the node into something other than an assignment, and of
984 -- course we only capture values if it is safe to do so.
986 if Is_Entity_Name
(Lhs
)
987 and then Nkind
(N
) = N_Assignment_Statement
990 Ent
: constant Entity_Id
:= Entity
(Lhs
);
993 if Safe_To_Capture_Value
(N
, Ent
) then
995 -- If simple variable on left side, warn if this assignment
996 -- blots out another one (rendering it useless). We only do
997 -- this for source assignments, otherwise we can generate bogus
998 -- warnings when an assignment is rewritten as another
999 -- assignment, and gets tied up with itself.
1001 -- There may have been a previous reference to a component of
1002 -- the variable, which in general removes the Last_Assignment
1003 -- field of the variable to indicate a relevant use of the
1004 -- previous assignment. However, if the assignment is to a
1005 -- subcomponent the reference may not have registered, because
1006 -- it is not possible to determine whether the context is an
1007 -- assignment. In those cases we generate a Deferred_Reference,
1008 -- to be used at the end of compilation to generate the right
1009 -- kind of reference, and we suppress a potential warning for
1010 -- a useless assignment, which might be premature. This may
1011 -- lose a warning in rare cases, but seems preferable to a
1012 -- misleading warning.
1014 if Warn_On_Modified_Unread
1015 and then Is_Assignable
(Ent
)
1016 and then Comes_From_Source
(N
)
1017 and then In_Extended_Main_Source_Unit
(Ent
)
1018 and then not Has_Deferred_Reference
(Ent
)
1020 Warn_On_Useless_Assignment
(Ent
, N
);
1023 -- If we are assigning an access type and the left side is an
1024 -- entity, then make sure that the Is_Known_[Non_]Null flags
1025 -- properly reflect the state of the entity after assignment.
1027 if Is_Access_Type
(T1
) then
1028 if Known_Non_Null
(Rhs
) then
1029 Set_Is_Known_Non_Null
(Ent
, True);
1031 elsif Known_Null
(Rhs
)
1032 and then not Can_Never_Be_Null
(Ent
)
1034 Set_Is_Known_Null
(Ent
, True);
1037 Set_Is_Known_Null
(Ent
, False);
1039 if not Can_Never_Be_Null
(Ent
) then
1040 Set_Is_Known_Non_Null
(Ent
, False);
1044 -- For discrete types, we may be able to set the current value
1045 -- if the value is known at compile time.
1047 elsif Is_Discrete_Type
(T1
)
1048 and then Compile_Time_Known_Value
(Rhs
)
1050 Set_Current_Value
(Ent
, Rhs
);
1052 Set_Current_Value
(Ent
, Empty
);
1055 -- If not safe to capture values, kill them
1063 -- If assigning to an object in whole or in part, note location of
1064 -- assignment in case no one references value. We only do this for
1065 -- source assignments, otherwise we can generate bogus warnings when an
1066 -- assignment is rewritten as another assignment, and gets tied up with
1070 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
1073 and then Safe_To_Capture_Value
(N
, Ent
)
1074 and then Nkind
(N
) = N_Assignment_Statement
1075 and then Warn_On_Modified_Unread
1076 and then Is_Assignable
(Ent
)
1077 and then Comes_From_Source
(N
)
1078 and then In_Extended_Main_Source_Unit
(Ent
)
1080 Set_Last_Assignment
(Ent
, Lhs
);
1084 Analyze_Dimension
(N
);
1087 Restore_Ghost_Mode
(Saved_GM
);
1089 -- If the right-hand side contains target names, expansion has been
1090 -- disabled to prevent expansion that might move target names out of
1091 -- the context of the assignment statement. Restore the expander mode
1092 -- now so that assignment statement can be properly expanded.
1094 if Nkind
(N
) = N_Assignment_Statement
then
1095 if Has_Target_Names
(N
) then
1096 Expander_Mode_Restore
;
1097 Full_Analysis
:= Save_Full_Analysis
;
1100 pragma Assert
(not Should_Transform_BIP_Assignment
(Typ
=> T1
));
1102 end Analyze_Assignment
;
1104 -----------------------------
1105 -- Analyze_Block_Statement --
1106 -----------------------------
1108 procedure Analyze_Block_Statement
(N
: Node_Id
) is
1109 procedure Install_Return_Entities
(Scop
: Entity_Id
);
1110 -- Install all entities of return statement scope Scop in the visibility
1111 -- chain except for the return object since its entity is reused in a
1114 -----------------------------
1115 -- Install_Return_Entities --
1116 -----------------------------
1118 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
1122 Id
:= First_Entity
(Scop
);
1123 while Present
(Id
) loop
1125 -- Do not install the return object
1127 if not Ekind_In
(Id
, E_Constant
, E_Variable
)
1128 or else not Is_Return_Object
(Id
)
1130 Install_Entity
(Id
);
1135 end Install_Return_Entities
;
1137 -- Local constants and variables
1139 Decls
: constant List_Id
:= Declarations
(N
);
1140 Id
: constant Node_Id
:= Identifier
(N
);
1141 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
1143 Is_BIP_Return_Statement
: Boolean;
1145 -- Start of processing for Analyze_Block_Statement
1148 -- In SPARK mode, we reject block statements. Note that the case of
1149 -- block statements generated by the expander is fine.
1151 if Nkind
(Original_Node
(N
)) = N_Block_Statement
then
1152 Check_SPARK_05_Restriction
("block statement is not allowed", N
);
1155 -- If no handled statement sequence is present, things are really messed
1156 -- up, and we just return immediately (defence against previous errors).
1159 Check_Error_Detected
;
1163 -- Detect whether the block is actually a rewritten return statement of
1164 -- a build-in-place function.
1166 Is_BIP_Return_Statement
:=
1168 and then Present
(Entity
(Id
))
1169 and then Ekind
(Entity
(Id
)) = E_Return_Statement
1170 and then Is_Build_In_Place_Function
1171 (Return_Applies_To
(Entity
(Id
)));
1173 -- Normal processing with HSS present
1176 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
1177 Ent
: Entity_Id
:= Empty
;
1180 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1181 -- Recursively save value of this global, will be restored on exit
1184 -- Initialize unblocked exit count for statements of begin block
1185 -- plus one for each exception handler that is present.
1187 Unblocked_Exit_Count
:= 1;
1189 if Present
(EH
) then
1190 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ List_Length
(EH
);
1193 -- If a label is present analyze it and mark it as referenced
1195 if Present
(Id
) then
1199 -- An error defense. If we have an identifier, but no entity, then
1200 -- something is wrong. If previous errors, then just remove the
1201 -- identifier and continue, otherwise raise an exception.
1204 Check_Error_Detected
;
1205 Set_Identifier
(N
, Empty
);
1208 Set_Ekind
(Ent
, E_Block
);
1209 Generate_Reference
(Ent
, N
, ' ');
1210 Generate_Definition
(Ent
);
1212 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
1213 Set_Label_Construct
(Parent
(Ent
), N
);
1218 -- If no entity set, create a label entity
1221 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
1222 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
1223 Set_Parent
(Ent
, N
);
1226 Set_Etype
(Ent
, Standard_Void_Type
);
1227 Set_Block_Node
(Ent
, Identifier
(N
));
1230 -- The block served as an extended return statement. Ensure that any
1231 -- entities created during the analysis and expansion of the return
1232 -- object declaration are once again visible.
1234 if Is_BIP_Return_Statement
then
1235 Install_Return_Entities
(Ent
);
1238 if Present
(Decls
) then
1239 Analyze_Declarations
(Decls
);
1241 Inspect_Deferred_Constant_Completion
(Decls
);
1245 Process_End_Label
(HSS
, 'e', Ent
);
1247 -- If exception handlers are present, then we indicate that enclosing
1248 -- scopes contain a block with handlers. We only need to mark non-
1251 if Present
(EH
) then
1254 Set_Has_Nested_Block_With_Handler
(S
);
1255 exit when Is_Overloadable
(S
)
1256 or else Ekind
(S
) = E_Package
1257 or else Is_Generic_Unit
(S
);
1262 Check_References
(Ent
);
1263 Update_Use_Clause_Chain
;
1266 if Unblocked_Exit_Count
= 0 then
1267 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1268 Check_Unreachable_Code
(N
);
1270 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1273 end Analyze_Block_Statement
;
1275 --------------------------------
1276 -- Analyze_Compound_Statement --
1277 --------------------------------
1279 procedure Analyze_Compound_Statement
(N
: Node_Id
) is
1281 Analyze_List
(Actions
(N
));
1282 end Analyze_Compound_Statement
;
1284 ----------------------------
1285 -- Analyze_Case_Statement --
1286 ----------------------------
1288 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1290 Exp_Type
: Entity_Id
;
1291 Exp_Btype
: Entity_Id
;
1294 Others_Present
: Boolean;
1295 -- Indicates if Others was present
1297 pragma Warnings
(Off
, Last_Choice
);
1298 -- Don't care about assigned value
1300 Statements_Analyzed
: Boolean := False;
1301 -- Set True if at least some statement sequences get analyzed. If False
1302 -- on exit, means we had a serious error that prevented full analysis of
1303 -- the case statement, and as a result it is not a good idea to output
1304 -- warning messages about unreachable code.
1306 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1307 -- Recursively save value of this global, will be restored on exit
1309 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1310 -- Error routine invoked by the generic instantiation below when the
1311 -- case statement has a non static choice.
1313 procedure Process_Statements
(Alternative
: Node_Id
);
1314 -- Analyzes the statements associated with a case alternative. Needed
1315 -- by instantiation below.
1317 package Analyze_Case_Choices
is new
1318 Generic_Analyze_Choices
1319 (Process_Associated_Node
=> Process_Statements
);
1320 use Analyze_Case_Choices
;
1321 -- Instantiation of the generic choice analysis package
1323 package Check_Case_Choices
is new
1324 Generic_Check_Choices
1325 (Process_Empty_Choice
=> No_OP
,
1326 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1327 Process_Associated_Node
=> No_OP
);
1328 use Check_Case_Choices
;
1329 -- Instantiation of the generic choice processing package
1331 -----------------------------
1332 -- Non_Static_Choice_Error --
1333 -----------------------------
1335 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1337 Flag_Non_Static_Expr
1338 ("choice given in case statement is not static!", Choice
);
1339 end Non_Static_Choice_Error
;
1341 ------------------------
1342 -- Process_Statements --
1343 ------------------------
1345 procedure Process_Statements
(Alternative
: Node_Id
) is
1346 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1350 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1351 Statements_Analyzed
:= True;
1353 -- An interesting optimization. If the case statement expression
1354 -- is a simple entity, then we can set the current value within an
1355 -- alternative if the alternative has one possible value.
1359 -- when 2 | 3 => beta
1360 -- when others => gamma
1362 -- Here we know that N is initially 1 within alpha, but for beta and
1363 -- gamma, we do not know anything more about the initial value.
1365 if Is_Entity_Name
(Exp
) then
1366 Ent
:= Entity
(Exp
);
1368 if Ekind_In
(Ent
, E_Variable
,
1372 if List_Length
(Choices
) = 1
1373 and then Nkind
(First
(Choices
)) in N_Subexpr
1374 and then Compile_Time_Known_Value
(First
(Choices
))
1376 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1379 Analyze_Statements
(Statements
(Alternative
));
1381 -- After analyzing the case, set the current value to empty
1382 -- since we won't know what it is for the next alternative
1383 -- (unless reset by this same circuit), or after the case.
1385 Set_Current_Value
(Entity
(Exp
), Empty
);
1390 -- Case where expression is not an entity name of a variable
1392 Analyze_Statements
(Statements
(Alternative
));
1393 end Process_Statements
;
1395 -- Start of processing for Analyze_Case_Statement
1398 Unblocked_Exit_Count
:= 0;
1399 Exp
:= Expression
(N
);
1402 -- The expression must be of any discrete type. In rare cases, the
1403 -- expander constructs a case statement whose expression has a private
1404 -- type whose full view is discrete. This can happen when generating
1405 -- a stream operation for a variant type after the type is frozen,
1406 -- when the partial of view of the type of the discriminant is private.
1407 -- In that case, use the full view to analyze case alternatives.
1409 if not Is_Overloaded
(Exp
)
1410 and then not Comes_From_Source
(N
)
1411 and then Is_Private_Type
(Etype
(Exp
))
1412 and then Present
(Full_View
(Etype
(Exp
)))
1413 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1415 Resolve
(Exp
, Etype
(Exp
));
1416 Exp_Type
:= Full_View
(Etype
(Exp
));
1419 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1420 Exp_Type
:= Etype
(Exp
);
1423 Check_Unset_Reference
(Exp
);
1424 Exp_Btype
:= Base_Type
(Exp_Type
);
1426 -- The expression must be of a discrete type which must be determinable
1427 -- independently of the context in which the expression occurs, but
1428 -- using the fact that the expression must be of a discrete type.
1429 -- Moreover, the type this expression must not be a character literal
1430 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1432 -- If error already reported by Resolve, nothing more to do
1434 if Exp_Btype
= Any_Discrete
or else Exp_Btype
= Any_Type
then
1437 elsif Exp_Btype
= Any_Character
then
1439 ("character literal as case expression is ambiguous", Exp
);
1442 elsif Ada_Version
= Ada_83
1443 and then (Is_Generic_Type
(Exp_Btype
)
1444 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1447 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1451 -- If the case expression is a formal object of mode in out, then treat
1452 -- it as having a nonstatic subtype by forcing use of the base type
1453 -- (which has to get passed to Check_Case_Choices below). Also use base
1454 -- type when the case expression is parenthesized.
1456 if Paren_Count
(Exp
) > 0
1457 or else (Is_Entity_Name
(Exp
)
1458 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1460 Exp_Type
:= Exp_Btype
;
1463 -- Call instantiated procedures to analyzwe and check discrete choices
1465 Analyze_Choices
(Alternatives
(N
), Exp_Type
);
1466 Check_Choices
(N
, Alternatives
(N
), Exp_Type
, Others_Present
);
1468 -- Case statement with single OTHERS alternative not allowed in SPARK
1470 if Others_Present
and then List_Length
(Alternatives
(N
)) = 1 then
1471 Check_SPARK_05_Restriction
1472 ("OTHERS as unique case alternative is not allowed", N
);
1475 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1476 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1479 -- If all our exits were blocked by unconditional transfers of control,
1480 -- then the entire CASE statement acts as an unconditional transfer of
1481 -- control, so treat it like one, and check unreachable code. Skip this
1482 -- test if we had serious errors preventing any statement analysis.
1484 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1485 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1486 Check_Unreachable_Code
(N
);
1488 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1491 -- If the expander is active it will detect the case of a statically
1492 -- determined single alternative and remove warnings for the case, but
1493 -- if we are not doing expansion, that circuit won't be active. Here we
1494 -- duplicate the effect of removing warnings in the same way, so that
1495 -- we will get the same set of warnings in -gnatc mode.
1497 if not Expander_Active
1498 and then Compile_Time_Known_Value
(Expression
(N
))
1499 and then Serious_Errors_Detected
= 0
1502 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1506 Alt
:= First
(Alternatives
(N
));
1507 while Present
(Alt
) loop
1508 if Alt
/= Chosen
then
1509 Remove_Warning_Messages
(Statements
(Alt
));
1516 end Analyze_Case_Statement
;
1518 ----------------------------
1519 -- Analyze_Exit_Statement --
1520 ----------------------------
1522 -- If the exit includes a name, it must be the name of a currently open
1523 -- loop. Otherwise there must be an innermost open loop on the stack, to
1524 -- which the statement implicitly refers.
1526 -- Additionally, in SPARK mode:
1528 -- The exit can only name the closest enclosing loop;
1530 -- An exit with a when clause must be directly contained in a loop;
1532 -- An exit without a when clause must be directly contained in an
1533 -- if-statement with no elsif or else, which is itself directly contained
1534 -- in a loop. The exit must be the last statement in the if-statement.
1536 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1537 Target
: constant Node_Id
:= Name
(N
);
1538 Cond
: constant Node_Id
:= Condition
(N
);
1539 Scope_Id
: Entity_Id
:= Empty
; -- initialize to prevent warning
1545 Check_Unreachable_Code
(N
);
1548 if Present
(Target
) then
1550 U_Name
:= Entity
(Target
);
1552 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1553 Error_Msg_N
("invalid loop name in exit statement", N
);
1557 if Has_Loop_In_Inner_Open_Scopes
(U_Name
) then
1558 Check_SPARK_05_Restriction
1559 ("exit label must name the closest enclosing loop", N
);
1562 Set_Has_Exit
(U_Name
);
1569 for J
in reverse 0 .. Scope_Stack
.Last
loop
1570 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1571 Kind
:= Ekind
(Scope_Id
);
1573 if Kind
= E_Loop
and then (No
(Target
) or else Scope_Id
= U_Name
) then
1574 Set_Has_Exit
(Scope_Id
);
1577 elsif Kind
= E_Block
1578 or else Kind
= E_Loop
1579 or else Kind
= E_Return_Statement
1585 ("cannot exit from program unit or accept statement", N
);
1590 -- Verify that if present the condition is a Boolean expression
1592 if Present
(Cond
) then
1593 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1594 Check_Unset_Reference
(Cond
);
1597 -- In SPARK mode, verify that the exit statement respects the SPARK
1600 if Present
(Cond
) then
1601 if Nkind
(Parent
(N
)) /= N_Loop_Statement
then
1602 Check_SPARK_05_Restriction
1603 ("exit with when clause must be directly in loop", N
);
1607 if Nkind
(Parent
(N
)) /= N_If_Statement
then
1608 if Nkind
(Parent
(N
)) = N_Elsif_Part
then
1609 Check_SPARK_05_Restriction
1610 ("exit must be in IF without ELSIF", N
);
1612 Check_SPARK_05_Restriction
("exit must be directly in IF", N
);
1615 elsif Nkind
(Parent
(Parent
(N
))) /= N_Loop_Statement
then
1616 Check_SPARK_05_Restriction
1617 ("exit must be in IF directly in loop", N
);
1619 -- First test the presence of ELSE, so that an exit in an ELSE leads
1620 -- to an error mentioning the ELSE.
1622 elsif Present
(Else_Statements
(Parent
(N
))) then
1623 Check_SPARK_05_Restriction
("exit must be in IF without ELSE", N
);
1625 -- An exit in an ELSIF does not reach here, as it would have been
1626 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1628 elsif Present
(Elsif_Parts
(Parent
(N
))) then
1629 Check_SPARK_05_Restriction
("exit must be in IF without ELSIF", N
);
1633 -- Chain exit statement to associated loop entity
1635 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1636 Set_First_Exit_Statement
(Scope_Id
, N
);
1638 -- Since the exit may take us out of a loop, any previous assignment
1639 -- statement is not useless, so clear last assignment indications. It
1640 -- is OK to keep other current values, since if the exit statement
1641 -- does not exit, then the current values are still valid.
1643 Kill_Current_Values
(Last_Assignment_Only
=> True);
1644 end Analyze_Exit_Statement
;
1646 ----------------------------
1647 -- Analyze_Goto_Statement --
1648 ----------------------------
1650 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1651 Label
: constant Node_Id
:= Name
(N
);
1652 Scope_Id
: Entity_Id
;
1653 Label_Scope
: Entity_Id
;
1654 Label_Ent
: Entity_Id
;
1657 Check_SPARK_05_Restriction
("goto statement is not allowed", N
);
1659 -- Actual semantic checks
1661 Check_Unreachable_Code
(N
);
1662 Kill_Current_Values
(Last_Assignment_Only
=> True);
1665 Label_Ent
:= Entity
(Label
);
1667 -- Ignore previous error
1669 if Label_Ent
= Any_Id
then
1670 Check_Error_Detected
;
1673 -- We just have a label as the target of a goto
1675 elsif Ekind
(Label_Ent
) /= E_Label
then
1676 Error_Msg_N
("target of goto statement must be a label", Label
);
1679 -- Check that the target of the goto is reachable according to Ada
1680 -- scoping rules. Note: the special gotos we generate for optimizing
1681 -- local handling of exceptions would violate these rules, but we mark
1682 -- such gotos as analyzed when built, so this code is never entered.
1684 elsif not Reachable
(Label_Ent
) then
1685 Error_Msg_N
("target of goto statement is not reachable", Label
);
1689 -- Here if goto passes initial validity checks
1691 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1693 for J
in reverse 0 .. Scope_Stack
.Last
loop
1694 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1696 if Label_Scope
= Scope_Id
1697 or else not Ekind_In
(Scope_Id
, E_Block
, E_Loop
, E_Return_Statement
)
1699 if Scope_Id
/= Label_Scope
then
1701 ("cannot exit from program unit or accept statement", N
);
1708 raise Program_Error
;
1709 end Analyze_Goto_Statement
;
1711 --------------------------
1712 -- Analyze_If_Statement --
1713 --------------------------
1715 -- A special complication arises in the analysis of if statements
1717 -- The expander has circuitry to completely delete code that it can tell
1718 -- will not be executed (as a result of compile time known conditions). In
1719 -- the analyzer, we ensure that code that will be deleted in this manner
1720 -- is analyzed but not expanded. This is obviously more efficient, but
1721 -- more significantly, difficulties arise if code is expanded and then
1722 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1723 -- generated in deleted code must be frozen from start, because the nodes
1724 -- on which they depend will not be available at the freeze point.
1726 procedure Analyze_If_Statement
(N
: Node_Id
) is
1729 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1730 -- Recursively save value of this global, will be restored on exit
1732 Save_In_Deleted_Code
: Boolean;
1734 Del
: Boolean := False;
1735 -- This flag gets set True if a True condition has been found, which
1736 -- means that remaining ELSE/ELSIF parts are deleted.
1738 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1739 -- This is applied to either the N_If_Statement node itself or to an
1740 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1741 -- statements associated with it.
1743 -----------------------
1744 -- Analyze_Cond_Then --
1745 -----------------------
1747 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1748 Cond
: constant Node_Id
:= Condition
(Cnode
);
1749 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1752 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1753 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1754 Check_Unset_Reference
(Cond
);
1755 Set_Current_Value_Condition
(Cnode
);
1757 -- If already deleting, then just analyze then statements
1760 Analyze_Statements
(Tstm
);
1762 -- Compile time known value, not deleting yet
1764 elsif Compile_Time_Known_Value
(Cond
) then
1765 Save_In_Deleted_Code
:= In_Deleted_Code
;
1767 -- If condition is True, then analyze the THEN statements and set
1768 -- no expansion for ELSE and ELSIF parts.
1770 if Is_True
(Expr_Value
(Cond
)) then
1771 Analyze_Statements
(Tstm
);
1773 Expander_Mode_Save_And_Set
(False);
1774 In_Deleted_Code
:= True;
1776 -- If condition is False, analyze THEN with expansion off
1778 else -- Is_False (Expr_Value (Cond))
1779 Expander_Mode_Save_And_Set
(False);
1780 In_Deleted_Code
:= True;
1781 Analyze_Statements
(Tstm
);
1782 Expander_Mode_Restore
;
1783 In_Deleted_Code
:= Save_In_Deleted_Code
;
1786 -- Not known at compile time, not deleting, normal analysis
1789 Analyze_Statements
(Tstm
);
1791 end Analyze_Cond_Then
;
1793 -- Start of processing for Analyze_If_Statement
1796 -- Initialize exit count for else statements. If there is no else part,
1797 -- this count will stay non-zero reflecting the fact that the uncovered
1798 -- else case is an unblocked exit.
1800 Unblocked_Exit_Count
:= 1;
1801 Analyze_Cond_Then
(N
);
1803 -- Now to analyze the elsif parts if any are present
1805 if Present
(Elsif_Parts
(N
)) then
1806 E
:= First
(Elsif_Parts
(N
));
1807 while Present
(E
) loop
1808 Analyze_Cond_Then
(E
);
1813 if Present
(Else_Statements
(N
)) then
1814 Analyze_Statements
(Else_Statements
(N
));
1817 -- If all our exits were blocked by unconditional transfers of control,
1818 -- then the entire IF statement acts as an unconditional transfer of
1819 -- control, so treat it like one, and check unreachable code.
1821 if Unblocked_Exit_Count
= 0 then
1822 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1823 Check_Unreachable_Code
(N
);
1825 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1829 Expander_Mode_Restore
;
1830 In_Deleted_Code
:= Save_In_Deleted_Code
;
1833 if not Expander_Active
1834 and then Compile_Time_Known_Value
(Condition
(N
))
1835 and then Serious_Errors_Detected
= 0
1837 if Is_True
(Expr_Value
(Condition
(N
))) then
1838 Remove_Warning_Messages
(Else_Statements
(N
));
1840 if Present
(Elsif_Parts
(N
)) then
1841 E
:= First
(Elsif_Parts
(N
));
1842 while Present
(E
) loop
1843 Remove_Warning_Messages
(Then_Statements
(E
));
1849 Remove_Warning_Messages
(Then_Statements
(N
));
1853 -- Warn on redundant if statement that has no effect
1855 -- Note, we could also check empty ELSIF parts ???
1857 if Warn_On_Redundant_Constructs
1859 -- If statement must be from source
1861 and then Comes_From_Source
(N
)
1863 -- Condition must not have obvious side effect
1865 and then Has_No_Obvious_Side_Effects
(Condition
(N
))
1867 -- No elsif parts of else part
1869 and then No
(Elsif_Parts
(N
))
1870 and then No
(Else_Statements
(N
))
1872 -- Then must be a single null statement
1874 and then List_Length
(Then_Statements
(N
)) = 1
1876 -- Go to original node, since we may have rewritten something as
1877 -- a null statement (e.g. a case we could figure the outcome of).
1880 T
: constant Node_Id
:= First
(Then_Statements
(N
));
1881 S
: constant Node_Id
:= Original_Node
(T
);
1884 if Comes_From_Source
(S
) and then Nkind
(S
) = N_Null_Statement
then
1885 Error_Msg_N
("if statement has no effect?r?", N
);
1889 end Analyze_If_Statement
;
1891 ----------------------------------------
1892 -- Analyze_Implicit_Label_Declaration --
1893 ----------------------------------------
1895 -- An implicit label declaration is generated in the innermost enclosing
1896 -- declarative part. This is done for labels, and block and loop names.
1898 -- Note: any changes in this routine may need to be reflected in
1899 -- Analyze_Label_Entity.
1901 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
1902 Id
: constant Node_Id
:= Defining_Identifier
(N
);
1905 Set_Ekind
(Id
, E_Label
);
1906 Set_Etype
(Id
, Standard_Void_Type
);
1907 Set_Enclosing_Scope
(Id
, Current_Scope
);
1908 end Analyze_Implicit_Label_Declaration
;
1910 ------------------------------
1911 -- Analyze_Iteration_Scheme --
1912 ------------------------------
1914 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
1916 Iter_Spec
: Node_Id
;
1917 Loop_Spec
: Node_Id
;
1920 -- For an infinite loop, there is no iteration scheme
1926 Cond
:= Condition
(N
);
1927 Iter_Spec
:= Iterator_Specification
(N
);
1928 Loop_Spec
:= Loop_Parameter_Specification
(N
);
1930 if Present
(Cond
) then
1931 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1932 Check_Unset_Reference
(Cond
);
1933 Set_Current_Value_Condition
(N
);
1935 elsif Present
(Iter_Spec
) then
1936 Analyze_Iterator_Specification
(Iter_Spec
);
1939 Analyze_Loop_Parameter_Specification
(Loop_Spec
);
1941 end Analyze_Iteration_Scheme
;
1943 ------------------------------------
1944 -- Analyze_Iterator_Specification --
1945 ------------------------------------
1947 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
1948 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
);
1949 -- For an iteration over a container, if the loop carries the Reverse
1950 -- indicator, verify that the container type has an Iterate aspect that
1951 -- implements the reversible iterator interface.
1953 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
;
1954 -- For containers with Iterator and related aspects, the cursor is
1955 -- obtained by locating an entity with the proper name in the scope
1958 -----------------------------
1959 -- Check_Reverse_Iteration --
1960 -----------------------------
1962 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
) is
1964 if Reverse_Present
(N
) then
1965 if Is_Array_Type
(Typ
)
1966 or else Is_Reversible_Iterator
(Typ
)
1968 (Present
(Find_Aspect
(Typ
, Aspect_Iterable
))
1971 (Get_Iterable_Type_Primitive
(Typ
, Name_Previous
)))
1976 ("container type does not support reverse iteration", N
, Typ
);
1979 end Check_Reverse_Iteration
;
1981 ---------------------
1982 -- Get_Cursor_Type --
1983 ---------------------
1985 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
is
1989 -- If iterator type is derived, the cursor is declared in the scope
1990 -- of the parent type.
1992 if Is_Derived_Type
(Typ
) then
1993 Ent
:= First_Entity
(Scope
(Etype
(Typ
)));
1995 Ent
:= First_Entity
(Scope
(Typ
));
1998 while Present
(Ent
) loop
1999 exit when Chars
(Ent
) = Name_Cursor
;
2007 -- The cursor is the target of generated assignments in the
2008 -- loop, and cannot have a limited type.
2010 if Is_Limited_Type
(Etype
(Ent
)) then
2011 Error_Msg_N
("cursor type cannot be limited", N
);
2015 end Get_Cursor_Type
;
2019 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
2020 Iter_Name
: constant Node_Id
:= Name
(N
);
2021 Loc
: constant Source_Ptr
:= Sloc
(N
);
2022 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
2024 Bas
: Entity_Id
:= Empty
; -- initialize to prevent warning
2027 -- Start of processing for Analyze_Iterator_Specification
2030 Enter_Name
(Def_Id
);
2032 -- AI12-0151 specifies that when the subtype indication is present, it
2033 -- must statically match the type of the array or container element.
2034 -- To simplify this check, we introduce a subtype declaration with the
2035 -- given subtype indication when it carries a constraint, and rewrite
2036 -- the original as a reference to the created subtype entity.
2038 if Present
(Subt
) then
2039 if Nkind
(Subt
) = N_Subtype_Indication
then
2041 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
2042 Decl
: constant Node_Id
:=
2043 Make_Subtype_Declaration
(Loc
,
2044 Defining_Identifier
=> S
,
2045 Subtype_Indication
=> New_Copy_Tree
(Subt
));
2047 Insert_Before
(Parent
(Parent
(N
)), Decl
);
2049 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
2055 -- Save entity of subtype indication for subsequent check
2057 Bas
:= Entity
(Subt
);
2060 Preanalyze_Range
(Iter_Name
);
2062 -- Set the kind of the loop variable, which is not visible within the
2065 Set_Ekind
(Def_Id
, E_Variable
);
2067 -- Provide a link between the iterator variable and the container, for
2068 -- subsequent use in cross-reference and modification information.
2070 if Of_Present
(N
) then
2071 Set_Related_Expression
(Def_Id
, Iter_Name
);
2073 -- For a container, the iterator is specified through the aspect
2075 if not Is_Array_Type
(Etype
(Iter_Name
)) then
2077 Iterator
: constant Entity_Id
:=
2078 Find_Value_Of_Aspect
2079 (Etype
(Iter_Name
), Aspect_Default_Iterator
);
2085 if No
(Iterator
) then
2086 null; -- error reported below
2088 elsif not Is_Overloaded
(Iterator
) then
2089 Check_Reverse_Iteration
(Etype
(Iterator
));
2091 -- If Iterator is overloaded, use reversible iterator if one is
2094 elsif Is_Overloaded
(Iterator
) then
2095 Get_First_Interp
(Iterator
, I
, It
);
2096 while Present
(It
.Nam
) loop
2097 if Ekind
(It
.Nam
) = E_Function
2098 and then Is_Reversible_Iterator
(Etype
(It
.Nam
))
2100 Set_Etype
(Iterator
, It
.Typ
);
2101 Set_Entity
(Iterator
, It
.Nam
);
2105 Get_Next_Interp
(I
, It
);
2108 Check_Reverse_Iteration
(Etype
(Iterator
));
2114 -- If the domain of iteration is an expression, create a declaration for
2115 -- it, so that finalization actions are introduced outside of the loop.
2116 -- The declaration must be a renaming because the body of the loop may
2117 -- assign to elements.
2119 if not Is_Entity_Name
(Iter_Name
)
2121 -- When the context is a quantified expression, the renaming
2122 -- declaration is delayed until the expansion phase if we are
2125 and then (Nkind
(Parent
(N
)) /= N_Quantified_Expression
2126 or else Operating_Mode
= Check_Semantics
)
2128 -- Do not perform this expansion for ASIS and when expansion is
2129 -- disabled, where the temporary may hide the transformation of a
2130 -- selected component into a prefixed function call, and references
2131 -- need to see the original expression.
2133 and then Expander_Active
2136 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
2142 -- If the domain of iteration is an array component that depends
2143 -- on a discriminant, create actual subtype for it. Pre-analysis
2144 -- does not generate the actual subtype of a selected component.
2146 if Nkind
(Iter_Name
) = N_Selected_Component
2147 and then Is_Array_Type
(Etype
(Iter_Name
))
2150 Build_Actual_Subtype_Of_Component
2151 (Etype
(Selector_Name
(Iter_Name
)), Iter_Name
);
2152 Insert_Action
(N
, Act_S
);
2154 if Present
(Act_S
) then
2155 Typ
:= Defining_Identifier
(Act_S
);
2157 Typ
:= Etype
(Iter_Name
);
2161 Typ
:= Etype
(Iter_Name
);
2163 -- Verify that the expression produces an iterator
2165 if not Of_Present
(N
) and then not Is_Iterator
(Typ
)
2166 and then not Is_Array_Type
(Typ
)
2167 and then No
(Find_Aspect
(Typ
, Aspect_Iterable
))
2170 ("expect object that implements iterator interface",
2175 -- Protect against malformed iterator
2177 if Typ
= Any_Type
then
2178 Error_Msg_N
("invalid expression in loop iterator", Iter_Name
);
2182 if not Of_Present
(N
) then
2183 Check_Reverse_Iteration
(Typ
);
2186 -- The name in the renaming declaration may be a function call.
2187 -- Indicate that it does not come from source, to suppress
2188 -- spurious warnings on renamings of parameterless functions,
2189 -- a common enough idiom in user-defined iterators.
2192 Make_Object_Renaming_Declaration
(Loc
,
2193 Defining_Identifier
=> Id
,
2194 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
2196 New_Copy_Tree
(Iter_Name
, New_Sloc
=> Loc
));
2198 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
2199 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
2200 Set_Etype
(Id
, Typ
);
2201 Set_Etype
(Name
(N
), Typ
);
2204 -- Container is an entity or an array with uncontrolled components, or
2205 -- else it is a container iterator given by a function call, typically
2206 -- called Iterate in the case of predefined containers, even though
2207 -- Iterate is not a reserved name. What matters is that the return type
2208 -- of the function is an iterator type.
2210 elsif Is_Entity_Name
(Iter_Name
) then
2211 Analyze
(Iter_Name
);
2213 if Nkind
(Iter_Name
) = N_Function_Call
then
2215 C
: constant Node_Id
:= Name
(Iter_Name
);
2220 if not Is_Overloaded
(Iter_Name
) then
2221 Resolve
(Iter_Name
, Etype
(C
));
2224 Get_First_Interp
(C
, I
, It
);
2225 while It
.Typ
/= Empty
loop
2226 if Reverse_Present
(N
) then
2227 if Is_Reversible_Iterator
(It
.Typ
) then
2228 Resolve
(Iter_Name
, It
.Typ
);
2232 elsif Is_Iterator
(It
.Typ
) then
2233 Resolve
(Iter_Name
, It
.Typ
);
2237 Get_Next_Interp
(I
, It
);
2242 -- Domain of iteration is not overloaded
2245 Resolve
(Iter_Name
, Etype
(Iter_Name
));
2248 if not Of_Present
(N
) then
2249 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2253 -- Get base type of container, for proper retrieval of Cursor type
2254 -- and primitive operations.
2256 Typ
:= Base_Type
(Etype
(Iter_Name
));
2258 if Is_Array_Type
(Typ
) then
2259 if Of_Present
(N
) then
2260 Set_Etype
(Def_Id
, Component_Type
(Typ
));
2262 -- The loop variable is aliased if the array components are
2265 Set_Is_Aliased
(Def_Id
, Has_Aliased_Components
(Typ
));
2267 -- AI12-0047 stipulates that the domain (array or container)
2268 -- cannot be a component that depends on a discriminant if the
2269 -- enclosing object is mutable, to prevent a modification of the
2270 -- dowmain of iteration in the course of an iteration.
2272 -- If the object is an expression it has been captured in a
2273 -- temporary, so examine original node.
2275 if Nkind
(Original_Node
(Iter_Name
)) = N_Selected_Component
2276 and then Is_Dependent_Component_Of_Mutable_Object
2277 (Original_Node
(Iter_Name
))
2280 ("iterable name cannot be a discriminant-dependent "
2281 & "component of a mutable object", N
);
2286 (Base_Type
(Bas
) /= Base_Type
(Component_Type
(Typ
))
2288 not Subtypes_Statically_Match
(Bas
, Component_Type
(Typ
)))
2291 ("subtype indication does not match component type", Subt
);
2294 -- Here we have a missing Range attribute
2298 ("missing Range attribute in iteration over an array", N
);
2300 -- In Ada 2012 mode, this may be an attempt at an iterator
2302 if Ada_Version
>= Ada_2012
then
2304 ("\if& is meant to designate an element of the array, use OF",
2308 -- Prevent cascaded errors
2310 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2311 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2314 -- Check for type error in iterator
2316 elsif Typ
= Any_Type
then
2319 -- Iteration over a container
2322 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2323 Error_Msg_Ada_2012_Feature
("container iterator", Sloc
(N
));
2327 if Of_Present
(N
) then
2328 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2330 Elt
: constant Entity_Id
:=
2331 Get_Iterable_Type_Primitive
(Typ
, Name_Element
);
2335 ("missing Element primitive for iteration", N
);
2337 Set_Etype
(Def_Id
, Etype
(Elt
));
2338 Check_Reverse_Iteration
(Typ
);
2342 -- For a predefined container, The type of the loop variable is
2343 -- the Iterator_Element aspect of the container type.
2347 Element
: constant Entity_Id
:=
2348 Find_Value_Of_Aspect
2349 (Typ
, Aspect_Iterator_Element
);
2350 Iterator
: constant Entity_Id
:=
2351 Find_Value_Of_Aspect
2352 (Typ
, Aspect_Default_Iterator
);
2353 Orig_Iter_Name
: constant Node_Id
:=
2354 Original_Node
(Iter_Name
);
2355 Cursor_Type
: Entity_Id
;
2358 if No
(Element
) then
2359 Error_Msg_NE
("cannot iterate over&", N
, Typ
);
2363 Set_Etype
(Def_Id
, Entity
(Element
));
2364 Cursor_Type
:= Get_Cursor_Type
(Typ
);
2365 pragma Assert
(Present
(Cursor_Type
));
2367 -- If subtype indication was given, verify that it covers
2368 -- the element type of the container.
2371 and then (not Covers
(Bas
, Etype
(Def_Id
))
2372 or else not Subtypes_Statically_Match
2373 (Bas
, Etype
(Def_Id
)))
2376 ("subtype indication does not match element type",
2380 -- If the container has a variable indexing aspect, the
2381 -- element is a variable and is modifiable in the loop.
2383 if Has_Aspect
(Typ
, Aspect_Variable_Indexing
) then
2384 Set_Ekind
(Def_Id
, E_Variable
);
2387 -- If the container is a constant, iterating over it
2388 -- requires a Constant_Indexing operation.
2390 if not Is_Variable
(Iter_Name
)
2391 and then not Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
2394 ("iteration over constant container require "
2395 & "constant_indexing aspect", N
);
2397 -- The Iterate function may have an in_out parameter,
2398 -- and a constant container is thus illegal.
2400 elsif Present
(Iterator
)
2401 and then Ekind
(Entity
(Iterator
)) = E_Function
2402 and then Ekind
(First_Formal
(Entity
(Iterator
))) /=
2404 and then not Is_Variable
(Iter_Name
)
2406 Error_Msg_N
("variable container expected", N
);
2409 -- Detect a case where the iterator denotes a component
2410 -- of a mutable object which depends on a discriminant.
2411 -- Note that the iterator may denote a function call in
2412 -- qualified form, in which case this check should not
2415 if Nkind
(Orig_Iter_Name
) = N_Selected_Component
2417 Present
(Entity
(Selector_Name
(Orig_Iter_Name
)))
2419 (Entity
(Selector_Name
(Orig_Iter_Name
)),
2422 and then Is_Dependent_Component_Of_Mutable_Object
2426 ("container cannot be a discriminant-dependent "
2427 & "component of a mutable object", N
);
2433 -- IN iterator, domain is a range, or a call to Iterate function
2436 -- For an iteration of the form IN, the name must denote an
2437 -- iterator, typically the result of a call to Iterate. Give a
2438 -- useful error message when the name is a container by itself.
2440 -- The type may be a formal container type, which has to have
2441 -- an Iterable aspect detailing the required primitives.
2443 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2444 and then not Is_Iterator
(Typ
)
2446 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2449 elsif not Has_Aspect
(Typ
, Aspect_Iterator_Element
) then
2451 ("cannot iterate over&", Name
(N
), Typ
);
2454 ("name must be an iterator, not a container", Name
(N
));
2457 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2461 ("\to iterate directly over the elements of a container, "
2462 & "write `of &`", Name
(N
), Original_Node
(Name
(N
)));
2464 -- No point in continuing analysis of iterator spec
2470 -- If the name is a call (typically prefixed) to some Iterate
2471 -- function, it has been rewritten as an object declaration.
2472 -- If that object is a selected component, verify that it is not
2473 -- a component of an unconstrained mutable object.
2475 if Nkind
(Iter_Name
) = N_Identifier
2476 or else (not Expander_Active
and Comes_From_Source
(Iter_Name
))
2479 Orig_Node
: constant Node_Id
:= Original_Node
(Iter_Name
);
2480 Iter_Kind
: constant Node_Kind
:= Nkind
(Orig_Node
);
2484 if Iter_Kind
= N_Selected_Component
then
2485 Obj
:= Prefix
(Orig_Node
);
2487 elsif Iter_Kind
= N_Function_Call
then
2488 Obj
:= First_Actual
(Orig_Node
);
2490 -- If neither, the name comes from source
2496 if Nkind
(Obj
) = N_Selected_Component
2497 and then Is_Dependent_Component_Of_Mutable_Object
(Obj
)
2500 ("container cannot be a discriminant-dependent "
2501 & "component of a mutable object", N
);
2506 -- The result type of Iterate function is the classwide type of
2507 -- the interface parent. We need the specific Cursor type defined
2508 -- in the container package. We obtain it by name for a predefined
2509 -- container, or through the Iterable aspect for a formal one.
2511 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2514 (Parent
(Find_Value_Of_Aspect
(Typ
, Aspect_Iterable
)),
2518 Set_Etype
(Def_Id
, Get_Cursor_Type
(Typ
));
2519 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2524 end Analyze_Iterator_Specification
;
2530 -- Note: the semantic work required for analyzing labels (setting them as
2531 -- reachable) was done in a prepass through the statements in the block,
2532 -- so that forward gotos would be properly handled. See Analyze_Statements
2533 -- for further details. The only processing required here is to deal with
2534 -- optimizations that depend on an assumption of sequential control flow,
2535 -- since of course the occurrence of a label breaks this assumption.
2537 procedure Analyze_Label
(N
: Node_Id
) is
2538 pragma Warnings
(Off
, N
);
2540 Kill_Current_Values
;
2543 --------------------------
2544 -- Analyze_Label_Entity --
2545 --------------------------
2547 procedure Analyze_Label_Entity
(E
: Entity_Id
) is
2549 Set_Ekind
(E
, E_Label
);
2550 Set_Etype
(E
, Standard_Void_Type
);
2551 Set_Enclosing_Scope
(E
, Current_Scope
);
2552 Set_Reachable
(E
, True);
2553 end Analyze_Label_Entity
;
2555 ------------------------------------------
2556 -- Analyze_Loop_Parameter_Specification --
2557 ------------------------------------------
2559 procedure Analyze_Loop_Parameter_Specification
(N
: Node_Id
) is
2560 Loop_Nod
: constant Node_Id
:= Parent
(Parent
(N
));
2562 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
2563 -- If the bounds are given by a 'Range reference on a function call
2564 -- that returns a controlled array, introduce an explicit declaration
2565 -- to capture the bounds, so that the function result can be finalized
2566 -- in timely fashion.
2568 procedure Check_Predicate_Use
(T
: Entity_Id
);
2569 -- Diagnose Attempt to iterate through non-static predicate. Note that
2570 -- a type with inherited predicates may have both static and dynamic
2571 -- forms. In this case it is not sufficent to check the static predicate
2572 -- function only, look for a dynamic predicate aspect as well.
2574 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean;
2575 -- N is the node for an arbitrary construct. This function searches the
2576 -- construct N to see if any expressions within it contain function
2577 -- calls that use the secondary stack, returning True if any such call
2578 -- is found, and False otherwise.
2580 procedure Process_Bounds
(R
: Node_Id
);
2581 -- If the iteration is given by a range, create temporaries and
2582 -- assignment statements block to capture the bounds and perform
2583 -- required finalization actions in case a bound includes a function
2584 -- call that uses the temporary stack. We first pre-analyze a copy of
2585 -- the range in order to determine the expected type, and analyze and
2586 -- resolve the original bounds.
2588 --------------------------------------
2589 -- Check_Controlled_Array_Attribute --
2590 --------------------------------------
2592 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
2594 if Nkind
(DS
) = N_Attribute_Reference
2595 and then Is_Entity_Name
(Prefix
(DS
))
2596 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
2597 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
2599 Is_Controlled
(Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
2600 and then Expander_Active
2603 Loc
: constant Source_Ptr
:= Sloc
(N
);
2604 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
2605 Indx
: constant Entity_Id
:=
2606 Base_Type
(Etype
(First_Index
(Arr
)));
2607 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
2612 Make_Subtype_Declaration
(Loc
,
2613 Defining_Identifier
=> Subt
,
2614 Subtype_Indication
=>
2615 Make_Subtype_Indication
(Loc
,
2616 Subtype_Mark
=> New_Occurrence_Of
(Indx
, Loc
),
2618 Make_Range_Constraint
(Loc
, Relocate_Node
(DS
))));
2619 Insert_Before
(Loop_Nod
, Decl
);
2623 Make_Attribute_Reference
(Loc
,
2624 Prefix
=> New_Occurrence_Of
(Subt
, Loc
),
2625 Attribute_Name
=> Attribute_Name
(DS
)));
2630 end Check_Controlled_Array_Attribute
;
2632 -------------------------
2633 -- Check_Predicate_Use --
2634 -------------------------
2636 procedure Check_Predicate_Use
(T
: Entity_Id
) is
2638 -- A predicated subtype is illegal in loops and related constructs
2639 -- if the predicate is not static, or if it is a non-static subtype
2640 -- of a statically predicated subtype.
2642 if Is_Discrete_Type
(T
)
2643 and then Has_Predicates
(T
)
2644 and then (not Has_Static_Predicate
(T
)
2645 or else not Is_Static_Subtype
(T
)
2646 or else Has_Dynamic_Predicate_Aspect
(T
))
2648 -- Seems a confusing message for the case of a static predicate
2649 -- with a non-static subtype???
2651 Bad_Predicated_Subtype_Use
2652 ("cannot use subtype& with non-static predicate for loop "
2653 & "iteration", Discrete_Subtype_Definition
(N
),
2654 T
, Suggest_Static
=> True);
2656 elsif Inside_A_Generic
2657 and then Is_Generic_Formal
(T
)
2658 and then Is_Discrete_Type
(T
)
2660 Set_No_Dynamic_Predicate_On_Actual
(T
);
2662 end Check_Predicate_Use
;
2664 ------------------------------------
2665 -- Has_Call_Using_Secondary_Stack --
2666 ------------------------------------
2668 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean is
2670 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
2671 -- Check if N is a function call which uses the secondary stack
2677 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
2680 Return_Typ
: Entity_Id
;
2683 if Nkind
(N
) = N_Function_Call
then
2686 -- Call using access to subprogram with explicit dereference
2688 if Nkind
(Nam
) = N_Explicit_Dereference
then
2689 Subp
:= Etype
(Nam
);
2691 -- Call using a selected component notation or Ada 2005 object
2692 -- operation notation
2694 elsif Nkind
(Nam
) = N_Selected_Component
then
2695 Subp
:= Entity
(Selector_Name
(Nam
));
2700 Subp
:= Entity
(Nam
);
2703 Return_Typ
:= Etype
(Subp
);
2705 if Is_Composite_Type
(Return_Typ
)
2706 and then not Is_Constrained
(Return_Typ
)
2710 elsif Sec_Stack_Needed_For_Return
(Subp
) then
2715 -- Continue traversing the tree
2720 function Check_Calls
is new Traverse_Func
(Check_Call
);
2722 -- Start of processing for Has_Call_Using_Secondary_Stack
2725 return Check_Calls
(N
) = Abandon
;
2726 end Has_Call_Using_Secondary_Stack
;
2728 --------------------
2729 -- Process_Bounds --
2730 --------------------
2732 procedure Process_Bounds
(R
: Node_Id
) is
2733 Loc
: constant Source_Ptr
:= Sloc
(N
);
2736 (Original_Bound
: Node_Id
;
2737 Analyzed_Bound
: Node_Id
;
2738 Typ
: Entity_Id
) return Node_Id
;
2739 -- Capture value of bound and return captured value
2746 (Original_Bound
: Node_Id
;
2747 Analyzed_Bound
: Node_Id
;
2748 Typ
: Entity_Id
) return Node_Id
2755 -- If the bound is a constant or an object, no need for a separate
2756 -- declaration. If the bound is the result of previous expansion
2757 -- it is already analyzed and should not be modified. Note that
2758 -- the Bound will be resolved later, if needed, as part of the
2759 -- call to Make_Index (literal bounds may need to be resolved to
2762 if Analyzed
(Original_Bound
) then
2763 return Original_Bound
;
2765 elsif Nkind_In
(Analyzed_Bound
, N_Integer_Literal
,
2766 N_Character_Literal
)
2767 or else Is_Entity_Name
(Analyzed_Bound
)
2769 Analyze_And_Resolve
(Original_Bound
, Typ
);
2770 return Original_Bound
;
2773 -- Normally, the best approach is simply to generate a constant
2774 -- declaration that captures the bound. However, there is a nasty
2775 -- case where this is wrong. If the bound is complex, and has a
2776 -- possible use of the secondary stack, we need to generate a
2777 -- separate assignment statement to ensure the creation of a block
2778 -- which will release the secondary stack.
2780 -- We prefer the constant declaration, since it leaves us with a
2781 -- proper trace of the value, useful in optimizations that get rid
2782 -- of junk range checks.
2784 if not Has_Call_Using_Secondary_Stack
(Analyzed_Bound
) then
2785 Analyze_And_Resolve
(Original_Bound
, Typ
);
2787 -- Ensure that the bound is valid. This check should not be
2788 -- generated when the range belongs to a quantified expression
2789 -- as the construct is still not expanded into its final form.
2791 if Nkind
(Parent
(R
)) /= N_Loop_Parameter_Specification
2792 or else Nkind
(Parent
(Parent
(R
))) /= N_Quantified_Expression
2794 Ensure_Valid
(Original_Bound
);
2797 Force_Evaluation
(Original_Bound
);
2798 return Original_Bound
;
2801 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
2803 -- Here we make a declaration with a separate assignment
2804 -- statement, and insert before loop header.
2807 Make_Object_Declaration
(Loc
,
2808 Defining_Identifier
=> Id
,
2809 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
2812 Make_Assignment_Statement
(Loc
,
2813 Name
=> New_Occurrence_Of
(Id
, Loc
),
2814 Expression
=> Relocate_Node
(Original_Bound
));
2816 Insert_Actions
(Loop_Nod
, New_List
(Decl
, Assign
));
2818 -- Now that this temporary variable is initialized we decorate it
2819 -- as safe-to-reevaluate to inform to the backend that no further
2820 -- asignment will be issued and hence it can be handled as side
2821 -- effect free. Note that this decoration must be done when the
2822 -- assignment has been analyzed because otherwise it will be
2823 -- rejected (see Analyze_Assignment).
2825 Set_Is_Safe_To_Reevaluate
(Id
);
2827 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
2829 if Nkind
(Assign
) = N_Assignment_Statement
then
2830 return Expression
(Assign
);
2832 return Original_Bound
;
2836 Hi
: constant Node_Id
:= High_Bound
(R
);
2837 Lo
: constant Node_Id
:= Low_Bound
(R
);
2838 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
2843 -- Start of processing for Process_Bounds
2846 Set_Parent
(R_Copy
, Parent
(R
));
2847 Preanalyze_Range
(R_Copy
);
2848 Typ
:= Etype
(R_Copy
);
2850 -- If the type of the discrete range is Universal_Integer, then the
2851 -- bound's type must be resolved to Integer, and any object used to
2852 -- hold the bound must also have type Integer, unless the literal
2853 -- bounds are constant-folded expressions with a user-defined type.
2855 if Typ
= Universal_Integer
then
2856 if Nkind
(Lo
) = N_Integer_Literal
2857 and then Present
(Etype
(Lo
))
2858 and then Scope
(Etype
(Lo
)) /= Standard_Standard
2862 elsif Nkind
(Hi
) = N_Integer_Literal
2863 and then Present
(Etype
(Hi
))
2864 and then Scope
(Etype
(Hi
)) /= Standard_Standard
2869 Typ
:= Standard_Integer
;
2875 New_Lo
:= One_Bound
(Lo
, Low_Bound
(R_Copy
), Typ
);
2876 New_Hi
:= One_Bound
(Hi
, High_Bound
(R_Copy
), Typ
);
2878 -- Propagate staticness to loop range itself, in case the
2879 -- corresponding subtype is static.
2881 if New_Lo
/= Lo
and then Is_OK_Static_Expression
(New_Lo
) then
2882 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo
));
2885 if New_Hi
/= Hi
and then Is_OK_Static_Expression
(New_Hi
) then
2886 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi
));
2892 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(N
);
2893 Id
: constant Entity_Id
:= Defining_Identifier
(N
);
2897 -- Start of processing for Analyze_Loop_Parameter_Specification
2902 -- We always consider the loop variable to be referenced, since the loop
2903 -- may be used just for counting purposes.
2905 Generate_Reference
(Id
, N
, ' ');
2907 -- Check for the case of loop variable hiding a local variable (used
2908 -- later on to give a nice warning if the hidden variable is never
2912 H
: constant Entity_Id
:= Homonym
(Id
);
2915 and then Ekind
(H
) = E_Variable
2916 and then Is_Discrete_Type
(Etype
(H
))
2917 and then Enclosing_Dynamic_Scope
(H
) = Enclosing_Dynamic_Scope
(Id
)
2919 Set_Hiding_Loop_Variable
(H
, Id
);
2923 -- Loop parameter specification must include subtype mark in SPARK
2925 if Nkind
(DS
) = N_Range
then
2926 Check_SPARK_05_Restriction
2927 ("loop parameter specification must include subtype mark", N
);
2930 -- Analyze the subtype definition and create temporaries for the bounds.
2931 -- Do not evaluate the range when preanalyzing a quantified expression
2932 -- because bounds expressed as function calls with side effects will be
2933 -- incorrectly replicated.
2935 if Nkind
(DS
) = N_Range
2936 and then Expander_Active
2937 and then Nkind
(Parent
(N
)) /= N_Quantified_Expression
2939 Process_Bounds
(DS
);
2941 -- Either the expander not active or the range of iteration is a subtype
2942 -- indication, an entity, or a function call that yields an aggregate or
2946 DS_Copy
:= New_Copy_Tree
(DS
);
2947 Set_Parent
(DS_Copy
, Parent
(DS
));
2948 Preanalyze_Range
(DS_Copy
);
2950 -- Ada 2012: If the domain of iteration is:
2952 -- a) a function call,
2953 -- b) an identifier that is not a type,
2954 -- c) an attribute reference 'Old (within a postcondition),
2955 -- d) an unchecked conversion or a qualified expression with
2956 -- the proper iterator type.
2958 -- then it is an iteration over a container. It was classified as
2959 -- a loop specification by the parser, and must be rewritten now
2960 -- to activate container iteration. The last case will occur within
2961 -- an expanded inlined call, where the expansion wraps an actual in
2962 -- an unchecked conversion when needed. The expression of the
2963 -- conversion is always an object.
2965 if Nkind
(DS_Copy
) = N_Function_Call
2967 or else (Is_Entity_Name
(DS_Copy
)
2968 and then not Is_Type
(Entity
(DS_Copy
)))
2970 or else (Nkind
(DS_Copy
) = N_Attribute_Reference
2971 and then Nam_In
(Attribute_Name
(DS_Copy
),
2972 Name_Loop_Entry
, Name_Old
))
2974 or else Has_Aspect
(Etype
(DS_Copy
), Aspect_Iterable
)
2976 or else Nkind
(DS_Copy
) = N_Unchecked_Type_Conversion
2977 or else (Nkind
(DS_Copy
) = N_Qualified_Expression
2978 and then Is_Iterator
(Etype
(DS_Copy
)))
2980 -- This is an iterator specification. Rewrite it as such and
2981 -- analyze it to capture function calls that may require
2982 -- finalization actions.
2985 I_Spec
: constant Node_Id
:=
2986 Make_Iterator_Specification
(Sloc
(N
),
2987 Defining_Identifier
=> Relocate_Node
(Id
),
2989 Subtype_Indication
=> Empty
,
2990 Reverse_Present
=> Reverse_Present
(N
));
2991 Scheme
: constant Node_Id
:= Parent
(N
);
2994 Set_Iterator_Specification
(Scheme
, I_Spec
);
2995 Set_Loop_Parameter_Specification
(Scheme
, Empty
);
2996 Analyze_Iterator_Specification
(I_Spec
);
2998 -- In a generic context, analyze the original domain of
2999 -- iteration, for name capture.
3001 if not Expander_Active
then
3005 -- Set kind of loop parameter, which may be used in the
3006 -- subsequent analysis of the condition in a quantified
3009 Set_Ekind
(Id
, E_Loop_Parameter
);
3013 -- Domain of iteration is not a function call, and is side-effect
3017 -- A quantified expression that appears in a pre/post condition
3018 -- is pre-analyzed several times. If the range is given by an
3019 -- attribute reference it is rewritten as a range, and this is
3020 -- done even with expansion disabled. If the type is already set
3021 -- do not reanalyze, because a range with static bounds may be
3022 -- typed Integer by default.
3024 if Nkind
(Parent
(N
)) = N_Quantified_Expression
3025 and then Present
(Etype
(DS
))
3038 -- Some additional checks if we are iterating through a type
3040 if Is_Entity_Name
(DS
)
3041 and then Present
(Entity
(DS
))
3042 and then Is_Type
(Entity
(DS
))
3044 -- The subtype indication may denote the completion of an incomplete
3045 -- type declaration.
3047 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
3048 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
3049 Set_Etype
(DS
, Entity
(DS
));
3052 Check_Predicate_Use
(Entity
(DS
));
3055 -- Error if not discrete type
3057 if not Is_Discrete_Type
(Etype
(DS
)) then
3058 Wrong_Type
(DS
, Any_Discrete
);
3059 Set_Etype
(DS
, Any_Type
);
3062 Check_Controlled_Array_Attribute
(DS
);
3064 if Nkind
(DS
) = N_Subtype_Indication
then
3065 Check_Predicate_Use
(Entity
(Subtype_Mark
(DS
)));
3068 Make_Index
(DS
, N
, In_Iter_Schm
=> True);
3069 Set_Ekind
(Id
, E_Loop_Parameter
);
3071 -- A quantified expression which appears in a pre- or post-condition may
3072 -- be analyzed multiple times. The analysis of the range creates several
3073 -- itypes which reside in different scopes depending on whether the pre-
3074 -- or post-condition has been expanded. Update the type of the loop
3075 -- variable to reflect the proper itype at each stage of analysis.
3078 or else Etype
(Id
) = Any_Type
3080 (Present
(Etype
(Id
))
3081 and then Is_Itype
(Etype
(Id
))
3082 and then Nkind
(Parent
(Loop_Nod
)) = N_Expression_With_Actions
3083 and then Nkind
(Original_Node
(Parent
(Loop_Nod
))) =
3084 N_Quantified_Expression
)
3086 Set_Etype
(Id
, Etype
(DS
));
3089 -- Treat a range as an implicit reference to the type, to inhibit
3090 -- spurious warnings.
3092 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
3093 Set_Is_Known_Valid
(Id
, True);
3095 -- The loop is not a declarative part, so the loop variable must be
3096 -- frozen explicitly. Do not freeze while preanalyzing a quantified
3097 -- expression because the freeze node will not be inserted into the
3098 -- tree due to flag Is_Spec_Expression being set.
3100 if Nkind
(Parent
(N
)) /= N_Quantified_Expression
then
3102 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
3104 if Is_Non_Empty_List
(Flist
) then
3105 Insert_Actions
(N
, Flist
);
3110 -- Case where we have a range or a subtype, get type bounds
3112 if Nkind_In
(DS
, N_Range
, N_Subtype_Indication
)
3113 and then not Error_Posted
(DS
)
3114 and then Etype
(DS
) /= Any_Type
3115 and then Is_Discrete_Type
(Etype
(DS
))
3122 if Nkind
(DS
) = N_Range
then
3123 L
:= Low_Bound
(DS
);
3124 H
:= High_Bound
(DS
);
3127 Type_Low_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
3129 Type_High_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
3132 -- Check for null or possibly null range and issue warning. We
3133 -- suppress such messages in generic templates and instances,
3134 -- because in practice they tend to be dubious in these cases. The
3135 -- check applies as well to rewritten array element loops where a
3136 -- null range may be detected statically.
3138 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> True) = GT
then
3140 -- Suppress the warning if inside a generic template or
3141 -- instance, since in practice they tend to be dubious in these
3142 -- cases since they can result from intended parameterization.
3144 if not Inside_A_Generic
and then not In_Instance
then
3146 -- Specialize msg if invalid values could make the loop
3147 -- non-null after all.
3149 if Compile_Time_Compare
3150 (L
, H
, Assume_Valid
=> False) = GT
3152 -- Since we know the range of the loop is null, set the
3153 -- appropriate flag to remove the loop entirely during
3156 Set_Is_Null_Loop
(Loop_Nod
);
3158 if Comes_From_Source
(N
) then
3160 ("??loop range is null, loop will not execute", DS
);
3163 -- Here is where the loop could execute because of
3164 -- invalid values, so issue appropriate message and in
3165 -- this case we do not set the Is_Null_Loop flag since
3166 -- the loop may execute.
3168 elsif Comes_From_Source
(N
) then
3170 ("??loop range may be null, loop may not execute",
3173 ("??can only execute if invalid values are present",
3178 -- In either case, suppress warnings in the body of the loop,
3179 -- since it is likely that these warnings will be inappropriate
3180 -- if the loop never actually executes, which is likely.
3182 Set_Suppress_Loop_Warnings
(Loop_Nod
);
3184 -- The other case for a warning is a reverse loop where the
3185 -- upper bound is the integer literal zero or one, and the
3186 -- lower bound may exceed this value.
3188 -- For example, we have
3190 -- for J in reverse N .. 1 loop
3192 -- In practice, this is very likely to be a case of reversing
3193 -- the bounds incorrectly in the range.
3195 elsif Reverse_Present
(N
)
3196 and then Nkind
(Original_Node
(H
)) = N_Integer_Literal
3198 (Intval
(Original_Node
(H
)) = Uint_0
3200 Intval
(Original_Node
(H
)) = Uint_1
)
3202 -- Lower bound may in fact be known and known not to exceed
3203 -- upper bound (e.g. reverse 0 .. 1) and that's OK.
3205 if Compile_Time_Known_Value
(L
)
3206 and then Expr_Value
(L
) <= Expr_Value
(H
)
3210 -- Otherwise warning is warranted
3213 Error_Msg_N
("??loop range may be null", DS
);
3214 Error_Msg_N
("\??bounds may be wrong way round", DS
);
3218 -- Check if either bound is known to be outside the range of the
3219 -- loop parameter type, this is e.g. the case of a loop from
3220 -- 20..X where the type is 1..19.
3222 -- Such a loop is dubious since either it raises CE or it executes
3223 -- zero times, and that cannot be useful!
3225 if Etype
(DS
) /= Any_Type
3226 and then not Error_Posted
(DS
)
3227 and then Nkind
(DS
) = N_Subtype_Indication
3228 and then Nkind
(Constraint
(DS
)) = N_Range_Constraint
3231 LLo
: constant Node_Id
:=
3232 Low_Bound
(Range_Expression
(Constraint
(DS
)));
3233 LHi
: constant Node_Id
:=
3234 High_Bound
(Range_Expression
(Constraint
(DS
)));
3236 Bad_Bound
: Node_Id
:= Empty
;
3237 -- Suspicious loop bound
3240 -- At this stage L, H are the bounds of the type, and LLo
3241 -- Lhi are the low bound and high bound of the loop.
3243 if Compile_Time_Compare
(LLo
, L
, Assume_Valid
=> True) = LT
3245 Compile_Time_Compare
(LLo
, H
, Assume_Valid
=> True) = GT
3250 if Compile_Time_Compare
(LHi
, L
, Assume_Valid
=> True) = LT
3252 Compile_Time_Compare
(LHi
, H
, Assume_Valid
=> True) = GT
3257 if Present
(Bad_Bound
) then
3259 ("suspicious loop bound out of range of "
3260 & "loop subtype??", Bad_Bound
);
3262 ("\loop executes zero times or raises "
3263 & "Constraint_Error??", Bad_Bound
);
3268 -- This declare block is about warnings, if we get an exception while
3269 -- testing for warnings, we simply abandon the attempt silently. This
3270 -- most likely occurs as the result of a previous error, but might
3271 -- just be an obscure case we have missed. In either case, not giving
3272 -- the warning is perfectly acceptable.
3275 when others => null;
3279 -- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)).
3280 -- This check is relevant only when SPARK_Mode is on as it is not a
3281 -- standard Ada legality check.
3283 if SPARK_Mode
= On
and then Is_Effectively_Volatile
(Id
) then
3284 Error_Msg_N
("loop parameter cannot be volatile", Id
);
3286 end Analyze_Loop_Parameter_Specification
;
3288 ----------------------------
3289 -- Analyze_Loop_Statement --
3290 ----------------------------
3292 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
3294 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean;
3295 -- Given a loop iteration scheme, determine whether it is an Ada 2012
3296 -- container iteration.
3298 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean;
3299 -- Determine whether loop statement N has been wrapped in a block to
3300 -- capture finalization actions that may be generated for container
3301 -- iterators. Prevents infinite recursion when block is analyzed.
3302 -- Routine is a noop if loop is single statement within source block.
3304 ---------------------------
3305 -- Is_Container_Iterator --
3306 ---------------------------
3308 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean is
3317 elsif Present
(Condition
(Iter
)) then
3320 -- for Def_Id in [reverse] Name loop
3321 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
3323 elsif Present
(Iterator_Specification
(Iter
)) then
3325 Nam
: constant Node_Id
:= Name
(Iterator_Specification
(Iter
));
3329 Nam_Copy
:= New_Copy_Tree
(Nam
);
3330 Set_Parent
(Nam_Copy
, Parent
(Nam
));
3331 Preanalyze_Range
(Nam_Copy
);
3333 -- The only two options here are iteration over a container or
3336 return not Is_Array_Type
(Etype
(Nam_Copy
));
3339 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
3343 LP
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3344 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(LP
);
3348 DS_Copy
:= New_Copy_Tree
(DS
);
3349 Set_Parent
(DS_Copy
, Parent
(DS
));
3350 Preanalyze_Range
(DS_Copy
);
3352 -- Check for a call to Iterate () or an expression with
3353 -- an iterator type.
3356 (Nkind
(DS_Copy
) = N_Function_Call
3357 and then Needs_Finalization
(Etype
(DS_Copy
)))
3358 or else Is_Iterator
(Etype
(DS_Copy
));
3361 end Is_Container_Iterator
;
3363 -------------------------
3364 -- Is_Wrapped_In_Block --
3365 -------------------------
3367 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean is
3373 -- Check if current scope is a block that is not a transient block.
3375 if Ekind
(Current_Scope
) /= E_Block
3376 or else No
(Block_Node
(Current_Scope
))
3382 Handled_Statement_Sequence
(Parent
(Block_Node
(Current_Scope
)));
3384 -- Skip leading pragmas that may be introduced for invariant and
3385 -- predicate checks.
3387 Stat
:= First
(Statements
(HSS
));
3388 while Present
(Stat
) and then Nkind
(Stat
) = N_Pragma
loop
3389 Stat
:= Next
(Stat
);
3392 return Stat
= N
and then No
(Next
(Stat
));
3394 end Is_Wrapped_In_Block
;
3396 -- Local declarations
3398 Id
: constant Node_Id
:= Identifier
(N
);
3399 Iter
: constant Node_Id
:= Iteration_Scheme
(N
);
3400 Loc
: constant Source_Ptr
:= Sloc
(N
);
3404 -- Start of processing for Analyze_Loop_Statement
3407 if Present
(Id
) then
3409 -- Make name visible, e.g. for use in exit statements. Loop labels
3410 -- are always considered to be referenced.
3415 -- Guard against serious error (typically, a scope mismatch when
3416 -- semantic analysis is requested) by creating loop entity to
3417 -- continue analysis.
3420 if Total_Errors_Detected
/= 0 then
3421 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3423 raise Program_Error
;
3426 -- Verify that the loop name is hot hidden by an unrelated
3427 -- declaration in an inner scope.
3429 elsif Ekind
(Ent
) /= E_Label
and then Ekind
(Ent
) /= E_Loop
then
3430 Error_Msg_Sloc
:= Sloc
(Ent
);
3431 Error_Msg_N
("implicit label declaration for & is hidden#", Id
);
3433 if Present
(Homonym
(Ent
))
3434 and then Ekind
(Homonym
(Ent
)) = E_Label
3436 Set_Entity
(Id
, Ent
);
3437 Set_Ekind
(Ent
, E_Loop
);
3441 Generate_Reference
(Ent
, N
, ' ');
3442 Generate_Definition
(Ent
);
3444 -- If we found a label, mark its type. If not, ignore it, since it
3445 -- means we have a conflicting declaration, which would already
3446 -- have been diagnosed at declaration time. Set Label_Construct
3447 -- of the implicit label declaration, which is not created by the
3448 -- parser for generic units.
3450 if Ekind
(Ent
) = E_Label
then
3451 Set_Ekind
(Ent
, E_Loop
);
3453 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
3454 Set_Label_Construct
(Parent
(Ent
), N
);
3459 -- Case of no identifier present. Create one and attach it to the
3460 -- loop statement for use as a scope and as a reference for later
3461 -- expansions. Indicate that the label does not come from source,
3462 -- and attach it to the loop statement so it is part of the tree,
3463 -- even without a full declaration.
3466 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3467 Set_Etype
(Ent
, Standard_Void_Type
);
3468 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Loc
));
3469 Set_Parent
(Ent
, N
);
3470 Set_Has_Created_Identifier
(N
);
3473 -- If the iterator specification has a syntactic error, transform
3474 -- construct into an infinite loop to prevent a crash and perform
3478 and then Present
(Iterator_Specification
(Iter
))
3479 and then Error_Posted
(Iterator_Specification
(Iter
))
3481 Set_Iteration_Scheme
(N
, Empty
);
3486 -- Iteration over a container in Ada 2012 involves the creation of a
3487 -- controlled iterator object. Wrap the loop in a block to ensure the
3488 -- timely finalization of the iterator and release of container locks.
3489 -- The same applies to the use of secondary stack when obtaining an
3492 if Ada_Version
>= Ada_2012
3493 and then Is_Container_Iterator
(Iter
)
3494 and then not Is_Wrapped_In_Block
(N
)
3497 Block_Nod
: Node_Id
;
3498 Block_Id
: Entity_Id
;
3502 Make_Block_Statement
(Loc
,
3503 Declarations
=> New_List
,
3504 Handled_Statement_Sequence
=>
3505 Make_Handled_Sequence_Of_Statements
(Loc
,
3506 Statements
=> New_List
(Relocate_Node
(N
))));
3508 Add_Block_Identifier
(Block_Nod
, Block_Id
);
3510 -- The expansion of iterator loops generates an iterator in order
3511 -- to traverse the elements of a container:
3513 -- Iter : <iterator type> := Iterate (Container)'reference;
3515 -- The iterator is controlled and returned on the secondary stack.
3516 -- The analysis of the call to Iterate establishes a transient
3517 -- scope to deal with the secondary stack management, but never
3518 -- really creates a physical block as this would kill the iterator
3519 -- too early (see Wrap_Transient_Declaration). To address this
3520 -- case, mark the generated block as needing secondary stack
3523 Set_Uses_Sec_Stack
(Block_Id
);
3525 Rewrite
(N
, Block_Nod
);
3531 -- Kill current values on entry to loop, since statements in the body of
3532 -- the loop may have been executed before the loop is entered. Similarly
3533 -- we kill values after the loop, since we do not know that the body of
3534 -- the loop was executed.
3536 Kill_Current_Values
;
3538 Analyze_Iteration_Scheme
(Iter
);
3540 -- Check for following case which merits a warning if the type E of is
3541 -- a multi-dimensional array (and no explicit subscript ranges present).
3547 and then Present
(Loop_Parameter_Specification
(Iter
))
3550 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3551 DSD
: constant Node_Id
:=
3552 Original_Node
(Discrete_Subtype_Definition
(LPS
));
3554 if Nkind
(DSD
) = N_Attribute_Reference
3555 and then Attribute_Name
(DSD
) = Name_Range
3556 and then No
(Expressions
(DSD
))
3559 Typ
: constant Entity_Id
:= Etype
(Prefix
(DSD
));
3561 if Is_Array_Type
(Typ
)
3562 and then Number_Dimensions
(Typ
) > 1
3563 and then Nkind
(Parent
(N
)) = N_Loop_Statement
3564 and then Present
(Iteration_Scheme
(Parent
(N
)))
3567 OIter
: constant Node_Id
:=
3568 Iteration_Scheme
(Parent
(N
));
3569 OLPS
: constant Node_Id
:=
3570 Loop_Parameter_Specification
(OIter
);
3571 ODSD
: constant Node_Id
:=
3572 Original_Node
(Discrete_Subtype_Definition
(OLPS
));
3574 if Nkind
(ODSD
) = N_Attribute_Reference
3575 and then Attribute_Name
(ODSD
) = Name_Range
3576 and then No
(Expressions
(ODSD
))
3577 and then Etype
(Prefix
(ODSD
)) = Typ
3579 Error_Msg_Sloc
:= Sloc
(ODSD
);
3581 ("inner range same as outer range#??", DSD
);
3590 -- Analyze the statements of the body except in the case of an Ada 2012
3591 -- iterator with the expander active. In this case the expander will do
3592 -- a rewrite of the loop into a while loop. We will then analyze the
3593 -- loop body when we analyze this while loop.
3595 -- We need to do this delay because if the container is for indefinite
3596 -- types the actual subtype of the components will only be determined
3597 -- when the cursor declaration is analyzed.
3599 -- If the expander is not active then we want to analyze the loop body
3600 -- now even in the Ada 2012 iterator case, since the rewriting will not
3601 -- be done. Insert the loop variable in the current scope, if not done
3602 -- when analysing the iteration scheme. Set its kind properly to detect
3603 -- improper uses in the loop body.
3605 -- In GNATprove mode, we do one of the above depending on the kind of
3606 -- loop. If it is an iterator over an array, then we do not analyze the
3607 -- loop now. We will analyze it after it has been rewritten by the
3608 -- special SPARK expansion which is activated in GNATprove mode. We need
3609 -- to do this so that other expansions that should occur in GNATprove
3610 -- mode take into account the specificities of the rewritten loop, in
3611 -- particular the introduction of a renaming (which needs to be
3614 -- In other cases in GNATprove mode then we want to analyze the loop
3615 -- body now, since no rewriting will occur. Within a generic the
3616 -- GNATprove mode is irrelevant, we must analyze the generic for
3617 -- non-local name capture.
3620 and then Present
(Iterator_Specification
(Iter
))
3623 and then Is_Iterator_Over_Array
(Iterator_Specification
(Iter
))
3624 and then not Inside_A_Generic
3628 elsif not Expander_Active
then
3630 I_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
3631 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3634 if Scope
(Id
) /= Current_Scope
then
3638 -- In an element iterator, The loop parameter is a variable if
3639 -- the domain of iteration (container or array) is a variable.
3641 if not Of_Present
(I_Spec
)
3642 or else not Is_Variable
(Name
(I_Spec
))
3644 Set_Ekind
(Id
, E_Loop_Parameter
);
3648 Analyze_Statements
(Statements
(N
));
3652 -- Pre-Ada2012 for-loops and while loops
3654 Analyze_Statements
(Statements
(N
));
3657 -- When the iteration scheme of a loop contains attribute 'Loop_Entry,
3658 -- the loop is transformed into a conditional block. Retrieve the loop.
3662 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
3663 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
3666 -- Finish up processing for the loop. We kill all current values, since
3667 -- in general we don't know if the statements in the loop have been
3668 -- executed. We could do a bit better than this with a loop that we
3669 -- know will execute at least once, but it's not worth the trouble and
3670 -- the front end is not in the business of flow tracing.
3672 Process_End_Label
(Stmt
, 'e', Ent
);
3674 Kill_Current_Values
;
3676 -- Check for infinite loop. Skip check for generated code, since it
3677 -- justs waste time and makes debugging the routine called harder.
3679 -- Note that we have to wait till the body of the loop is fully analyzed
3680 -- before making this call, since Check_Infinite_Loop_Warning relies on
3681 -- being able to use semantic visibility information to find references.
3683 if Comes_From_Source
(Stmt
) then
3684 Check_Infinite_Loop_Warning
(Stmt
);
3687 -- Code after loop is unreachable if the loop has no WHILE or FOR and
3688 -- contains no EXIT statements within the body of the loop.
3690 if No
(Iter
) and then not Has_Exit
(Ent
) then
3691 Check_Unreachable_Code
(Stmt
);
3693 end Analyze_Loop_Statement
;
3695 ----------------------------
3696 -- Analyze_Null_Statement --
3697 ----------------------------
3699 -- Note: the semantics of the null statement is implemented by a single
3700 -- null statement, too bad everything isn't as simple as this.
3702 procedure Analyze_Null_Statement
(N
: Node_Id
) is
3703 pragma Warnings
(Off
, N
);
3706 end Analyze_Null_Statement
;
3708 -------------------------
3709 -- Analyze_Target_Name --
3710 -------------------------
3712 procedure Analyze_Target_Name
(N
: Node_Id
) is
3714 -- A target name has the type of the left-hand side of the enclosing
3717 Set_Etype
(N
, Etype
(Name
(Current_Assignment
)));
3718 end Analyze_Target_Name
;
3720 ------------------------
3721 -- Analyze_Statements --
3722 ------------------------
3724 procedure Analyze_Statements
(L
: List_Id
) is
3729 -- The labels declared in the statement list are reachable from
3730 -- statements in the list. We do this as a prepass so that any goto
3731 -- statement will be properly flagged if its target is not reachable.
3732 -- This is not required, but is nice behavior.
3735 while Present
(S
) loop
3736 if Nkind
(S
) = N_Label
then
3737 Analyze
(Identifier
(S
));
3738 Lab
:= Entity
(Identifier
(S
));
3740 -- If we found a label mark it as reachable
3742 if Ekind
(Lab
) = E_Label
then
3743 Generate_Definition
(Lab
);
3744 Set_Reachable
(Lab
);
3746 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
3747 Set_Label_Construct
(Parent
(Lab
), S
);
3750 -- If we failed to find a label, it means the implicit declaration
3751 -- of the label was hidden. A for-loop parameter can do this to
3752 -- a label with the same name inside the loop, since the implicit
3753 -- label declaration is in the innermost enclosing body or block
3757 Error_Msg_Sloc
:= Sloc
(Lab
);
3759 ("implicit label declaration for & is hidden#",
3767 -- Perform semantic analysis on all statements
3769 Conditional_Statements_Begin
;
3772 while Present
(S
) loop
3775 -- Remove dimension in all statements
3777 Remove_Dimension_In_Statement
(S
);
3781 Conditional_Statements_End
;
3783 -- Make labels unreachable. Visibility is not sufficient, because labels
3784 -- in one if-branch for example are not reachable from the other branch,
3785 -- even though their declarations are in the enclosing declarative part.
3788 while Present
(S
) loop
3789 if Nkind
(S
) = N_Label
then
3790 Set_Reachable
(Entity
(Identifier
(S
)), False);
3795 end Analyze_Statements
;
3797 ----------------------------
3798 -- Check_Unreachable_Code --
3799 ----------------------------
3801 procedure Check_Unreachable_Code
(N
: Node_Id
) is
3802 Error_Node
: Node_Id
;
3806 if Is_List_Member
(N
) and then Comes_From_Source
(N
) then
3811 Nxt
:= Original_Node
(Next
(N
));
3813 -- Skip past pragmas
3815 while Nkind
(Nxt
) = N_Pragma
loop
3816 Nxt
:= Original_Node
(Next
(Nxt
));
3819 -- If a label follows us, then we never have dead code, since
3820 -- someone could branch to the label, so we just ignore it, unless
3821 -- we are in formal mode where goto statements are not allowed.
3823 if Nkind
(Nxt
) = N_Label
3824 and then not Restriction_Check_Required
(SPARK_05
)
3828 -- Otherwise see if we have a real statement following us
3831 and then Comes_From_Source
(Nxt
)
3832 and then Is_Statement
(Nxt
)
3834 -- Special very annoying exception. If we have a return that
3835 -- follows a raise, then we allow it without a warning, since
3836 -- the Ada RM annoyingly requires a useless return here.
3838 if Nkind
(Original_Node
(N
)) /= N_Raise_Statement
3839 or else Nkind
(Nxt
) /= N_Simple_Return_Statement
3841 -- The rather strange shenanigans with the warning message
3842 -- here reflects the fact that Kill_Dead_Code is very good
3843 -- at removing warnings in deleted code, and this is one
3844 -- warning we would prefer NOT to have removed.
3848 -- If we have unreachable code, analyze and remove the
3849 -- unreachable code, since it is useless and we don't
3850 -- want to generate junk warnings.
3852 -- We skip this step if we are not in code generation mode
3853 -- or CodePeer mode.
3855 -- This is the one case where we remove dead code in the
3856 -- semantics as opposed to the expander, and we do not want
3857 -- to remove code if we are not in code generation mode,
3858 -- since this messes up the ASIS trees or loses useful
3859 -- information in the CodePeer tree.
3861 -- Note that one might react by moving the whole circuit to
3862 -- exp_ch5, but then we lose the warning in -gnatc mode.
3864 if Operating_Mode
= Generate_Code
3865 and then not CodePeer_Mode
3870 -- Quit deleting when we have nothing more to delete
3871 -- or if we hit a label (since someone could transfer
3872 -- control to a label, so we should not delete it).
3874 exit when No
(Nxt
) or else Nkind
(Nxt
) = N_Label
;
3876 -- Statement/declaration is to be deleted
3880 Kill_Dead_Code
(Nxt
);
3884 -- Now issue the warning (or error in formal mode)
3886 if Restriction_Check_Required
(SPARK_05
) then
3887 Check_SPARK_05_Restriction
3888 ("unreachable code is not allowed", Error_Node
);
3891 ("??unreachable code!", Sloc
(Error_Node
), Error_Node
);
3895 -- If the unconditional transfer of control instruction is the
3896 -- last statement of a sequence, then see if our parent is one of
3897 -- the constructs for which we count unblocked exits, and if so,
3898 -- adjust the count.
3903 -- Statements in THEN part or ELSE part of IF statement
3905 if Nkind
(P
) = N_If_Statement
then
3908 -- Statements in ELSIF part of an IF statement
3910 elsif Nkind
(P
) = N_Elsif_Part
then
3912 pragma Assert
(Nkind
(P
) = N_If_Statement
);
3914 -- Statements in CASE statement alternative
3916 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
3918 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
3920 -- Statements in body of block
3922 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
3923 and then Nkind
(Parent
(P
)) = N_Block_Statement
3925 -- The original loop is now placed inside a block statement
3926 -- due to the expansion of attribute 'Loop_Entry. Return as
3927 -- this is not a "real" block for the purposes of exit
3930 if Nkind
(N
) = N_Loop_Statement
3931 and then Subject_To_Loop_Entry_Attributes
(N
)
3936 -- Statements in exception handler in a block
3938 elsif Nkind
(P
) = N_Exception_Handler
3939 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
3940 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
3944 -- None of these cases, so return
3950 -- This was one of the cases we are looking for (i.e. the
3951 -- parent construct was IF, CASE or block) so decrement count.
3953 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
3957 end Check_Unreachable_Code
;
3959 ----------------------
3960 -- Preanalyze_Range --
3961 ----------------------
3963 procedure Preanalyze_Range
(R_Copy
: Node_Id
) is
3964 Save_Analysis
: constant Boolean := Full_Analysis
;
3968 Full_Analysis
:= False;
3969 Expander_Mode_Save_And_Set
(False);
3973 if Nkind
(R_Copy
) in N_Subexpr
and then Is_Overloaded
(R_Copy
) then
3975 -- Apply preference rules for range of predefined integer types, or
3976 -- check for array or iterable construct for "of" iterator, or
3977 -- diagnose true ambiguity.
3982 Found
: Entity_Id
:= Empty
;
3985 Get_First_Interp
(R_Copy
, I
, It
);
3986 while Present
(It
.Typ
) loop
3987 if Is_Discrete_Type
(It
.Typ
) then
3991 if Scope
(Found
) = Standard_Standard
then
3994 elsif Scope
(It
.Typ
) = Standard_Standard
then
3998 -- Both of them are user-defined
4001 ("ambiguous bounds in range of iteration", R_Copy
);
4002 Error_Msg_N
("\possible interpretations:", R_Copy
);
4003 Error_Msg_NE
("\\} ", R_Copy
, Found
);
4004 Error_Msg_NE
("\\} ", R_Copy
, It
.Typ
);
4009 elsif Nkind
(Parent
(R_Copy
)) = N_Iterator_Specification
4010 and then Of_Present
(Parent
(R_Copy
))
4012 if Is_Array_Type
(It
.Typ
)
4013 or else Has_Aspect
(It
.Typ
, Aspect_Iterator_Element
)
4014 or else Has_Aspect
(It
.Typ
, Aspect_Constant_Indexing
)
4015 or else Has_Aspect
(It
.Typ
, Aspect_Variable_Indexing
)
4019 Set_Etype
(R_Copy
, It
.Typ
);
4022 Error_Msg_N
("ambiguous domain of iteration", R_Copy
);
4027 Get_Next_Interp
(I
, It
);
4032 -- Subtype mark in iteration scheme
4034 if Is_Entity_Name
(R_Copy
) and then Is_Type
(Entity
(R_Copy
)) then
4037 -- Expression in range, or Ada 2012 iterator
4039 elsif Nkind
(R_Copy
) in N_Subexpr
then
4041 Typ
:= Etype
(R_Copy
);
4043 if Is_Discrete_Type
(Typ
) then
4046 -- Check that the resulting object is an iterable container
4048 elsif Has_Aspect
(Typ
, Aspect_Iterator_Element
)
4049 or else Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
4050 or else Has_Aspect
(Typ
, Aspect_Variable_Indexing
)
4054 -- The expression may yield an implicit reference to an iterable
4055 -- container. Insert explicit dereference so that proper type is
4056 -- visible in the loop.
4058 elsif Has_Implicit_Dereference
(Etype
(R_Copy
)) then
4063 Disc
:= First_Discriminant
(Typ
);
4064 while Present
(Disc
) loop
4065 if Has_Implicit_Dereference
(Disc
) then
4066 Build_Explicit_Dereference
(R_Copy
, Disc
);
4070 Next_Discriminant
(Disc
);
4077 Expander_Mode_Restore
;
4078 Full_Analysis
:= Save_Analysis
;
4079 end Preanalyze_Range
;