1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2018, 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.
110 function Is_Protected_Part_Of_Constituent
111 (Nod
: Node_Id
) return Boolean;
112 -- Determine whether arbitrary node Nod denotes a Part_Of constituent of
113 -- a single protected type.
116 -- This is called to kill current value settings of a simple variable
117 -- on the left hand side. We call it if we find any error in analyzing
118 -- the assignment, and at the end of processing before setting any new
119 -- current values in place.
121 procedure Set_Assignment_Type
123 Opnd_Type
: in out Entity_Id
);
124 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
125 -- nominal subtype. This procedure is used to deal with cases where the
126 -- nominal subtype must be replaced by the actual subtype.
128 procedure Transform_BIP_Assignment
(Typ
: Entity_Id
);
129 function Should_Transform_BIP_Assignment
130 (Typ
: Entity_Id
) return Boolean;
131 -- If the right-hand side of an assignment statement is a build-in-place
132 -- call we cannot build in place, so we insert a temp initialized with
133 -- the call, and transform the assignment statement to copy the temp.
134 -- Transform_BIP_Assignment does the tranformation, and
135 -- Should_Transform_BIP_Assignment determines whether we should.
136 -- The same goes for qualified expressions and conversions whose
137 -- operand is such a call.
139 -- This is only for nonlimited types; assignment statements are illegal
140 -- for limited types, but are generated internally for aggregates and
141 -- init procs. These limited-type are not really assignment statements
142 -- -- conceptually, they are initializations, so should not be
145 -- Similarly, for nonlimited types, aggregates and init procs generate
146 -- assignment statements that are really initializations. These are
147 -- marked No_Ctrl_Actions.
149 function Within_Function
return Boolean;
150 -- Determine whether the current scope is a function or appears within
153 -------------------------------
154 -- Diagnose_Non_Variable_Lhs --
155 -------------------------------
157 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
159 -- Not worth posting another error if left hand side already flagged
160 -- as being illegal in some respect.
162 if Error_Posted
(N
) then
165 -- Some special bad cases of entity names
167 elsif Is_Entity_Name
(N
) then
169 Ent
: constant Entity_Id
:= Entity
(N
);
172 if Ekind
(Ent
) = E_In_Parameter
then
174 ("assignment to IN mode parameter not allowed", N
);
177 -- Renamings of protected private components are turned into
178 -- constants when compiling a protected function. In the case
179 -- of single protected types, the private component appears
182 elsif (Is_Prival
(Ent
) and then Within_Function
)
184 (Ekind
(Ent
) = E_Component
185 and then Is_Protected_Type
(Scope
(Ent
)))
188 ("protected function cannot modify protected object", N
);
191 elsif Ekind
(Ent
) = E_Loop_Parameter
then
192 Error_Msg_N
("assignment to loop parameter not allowed", N
);
197 -- For indexed components, test prefix if it is in array. We do not
198 -- want to recurse for cases where the prefix is a pointer, since we
199 -- may get a message confusing the pointer and what it references.
201 elsif Nkind
(N
) = N_Indexed_Component
202 and then Is_Array_Type
(Etype
(Prefix
(N
)))
204 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
207 -- Another special case for assignment to discriminant
209 elsif Nkind
(N
) = N_Selected_Component
then
210 if Present
(Entity
(Selector_Name
(N
)))
211 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
213 Error_Msg_N
("assignment to discriminant not allowed", N
);
216 -- For selection from record, diagnose prefix, but note that again
217 -- we only do this for a record, not e.g. for a pointer.
219 elsif Is_Record_Type
(Etype
(Prefix
(N
))) then
220 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
225 -- If we fall through, we have no special message to issue
227 Error_Msg_N
("left hand side of assignment must be a variable", N
);
228 end Diagnose_Non_Variable_Lhs
;
230 --------------------------------------
231 -- Is_Protected_Part_Of_Constituent --
232 --------------------------------------
234 function Is_Protected_Part_Of_Constituent
235 (Nod
: Node_Id
) return Boolean
237 Encap_Id
: Entity_Id
;
241 -- Abstract states and variables may act as Part_Of constituents of
242 -- single protected types, however only variables can be modified by
245 if Is_Entity_Name
(Nod
) then
246 Var_Id
:= Entity
(Nod
);
248 if Present
(Var_Id
) and then Ekind
(Var_Id
) = E_Variable
then
249 Encap_Id
:= Encapsulating_State
(Var_Id
);
251 -- To qualify, the node must denote a reference to a variable
252 -- whose encapsulating state is a single protected object.
256 and then Is_Single_Protected_Object
(Encap_Id
);
261 end Is_Protected_Part_Of_Constituent
;
267 procedure Kill_Lhs
is
269 if Is_Entity_Name
(Lhs
) then
271 Ent
: constant Entity_Id
:= Entity
(Lhs
);
273 if Present
(Ent
) then
274 Kill_Current_Values
(Ent
);
280 -------------------------
281 -- Set_Assignment_Type --
282 -------------------------
284 procedure Set_Assignment_Type
286 Opnd_Type
: in out Entity_Id
)
291 Require_Entity
(Opnd
);
293 -- If the assignment operand is an in-out or out parameter, then we
294 -- get the actual subtype (needed for the unconstrained case). If the
295 -- operand is the actual in an entry declaration, then within the
296 -- accept statement it is replaced with a local renaming, which may
297 -- also have an actual subtype.
299 if Is_Entity_Name
(Opnd
)
300 and then (Ekind
(Entity
(Opnd
)) = E_Out_Parameter
301 or else Ekind_In
(Entity
(Opnd
),
303 E_Generic_In_Out_Parameter
)
305 (Ekind
(Entity
(Opnd
)) = E_Variable
306 and then Nkind
(Parent
(Entity
(Opnd
))) =
307 N_Object_Renaming_Declaration
308 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
311 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
313 -- If assignment operand is a component reference, then we get the
314 -- actual subtype of the component for the unconstrained case.
316 elsif Nkind_In
(Opnd
, N_Selected_Component
, N_Explicit_Dereference
)
317 and then not Is_Unchecked_Union
(Opnd_Type
)
319 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
321 if Present
(Decl
) then
322 Insert_Action
(N
, Decl
);
323 Mark_Rewrite_Insertion
(Decl
);
325 Opnd_Type
:= Defining_Identifier
(Decl
);
326 Set_Etype
(Opnd
, Opnd_Type
);
327 Freeze_Itype
(Opnd_Type
, N
);
329 elsif Is_Constrained
(Etype
(Opnd
)) then
330 Opnd_Type
:= Etype
(Opnd
);
333 -- For slice, use the constrained subtype created for the slice
335 elsif Nkind
(Opnd
) = N_Slice
then
336 Opnd_Type
:= Etype
(Opnd
);
338 end Set_Assignment_Type
;
340 -------------------------------------
341 -- Should_Transform_BIP_Assignment --
342 -------------------------------------
344 function Should_Transform_BIP_Assignment
345 (Typ
: Entity_Id
) return Boolean
351 and then not Is_Limited_View
(Typ
)
352 and then Is_Build_In_Place_Result_Type
(Typ
)
353 and then not No_Ctrl_Actions
(N
)
355 -- This function is called early, before name resolution is
356 -- complete, so we have to deal with things that might turn into
357 -- function calls later. N_Function_Call and N_Op nodes are the
358 -- obvious case. An N_Identifier or N_Expanded_Name is a
359 -- parameterless function call if it denotes a function.
360 -- Finally, an attribute reference can be a function call.
362 case Nkind
(Unqual_Conv
(Rhs
)) is
371 case Ekind
(Entity
(Unqual_Conv
(Rhs
))) is
381 when N_Attribute_Reference
=>
382 Result
:= Attribute_Name
(Unqual_Conv
(Rhs
)) = Name_Input
;
383 -- T'Input will turn into a call whose result type is T
393 end Should_Transform_BIP_Assignment
;
395 ------------------------------
396 -- Transform_BIP_Assignment --
397 ------------------------------
399 procedure Transform_BIP_Assignment
(Typ
: Entity_Id
) is
401 -- Tranform "X : [constant] T := F (...);" into:
403 -- Temp : constant T := F (...);
406 Loc
: constant Source_Ptr
:= Sloc
(N
);
407 Def_Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'Y', Rhs
);
408 Obj_Decl
: constant Node_Id
:=
409 Make_Object_Declaration
(Loc
,
410 Defining_Identifier
=> Def_Id
,
411 Constant_Present
=> True,
412 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
),
414 Has_Init_Expression
=> True);
417 Set_Etype
(Def_Id
, Typ
);
418 Set_Expression
(N
, New_Occurrence_Of
(Def_Id
, Loc
));
420 -- At this point, Rhs is no longer equal to Expression (N), so:
422 Rhs
:= Expression
(N
);
424 Insert_Action
(N
, Obj_Decl
);
425 end Transform_BIP_Assignment
;
427 ---------------------
428 -- Within_Function --
429 ---------------------
431 function Within_Function
return Boolean is
432 Scop_Id
: constant Entity_Id
:= Current_Scope
;
435 if Ekind
(Scop_Id
) = E_Function
then
438 elsif Ekind
(Enclosing_Dynamic_Scope
(Scop_Id
)) = E_Function
then
450 Save_Full_Analysis
: Boolean := False;
451 -- Force initialization to facilitate static analysis
453 Saved_GM
: constant Ghost_Mode_Type
:= Ghost_Mode
;
454 Saved_IGR
: constant Node_Id
:= Ignored_Ghost_Region
;
455 -- Save the Ghost-related attributes to restore on exit
457 -- Start of processing for Analyze_Assignment
460 Mark_Coextensions
(N
, Rhs
);
462 -- Preserve relevant elaboration-related attributes of the context which
463 -- are no longer available or very expensive to recompute once analysis,
464 -- resolution, and expansion are over.
466 Mark_Elaboration_Attributes
471 -- Analyze the target of the assignment first in case the expression
472 -- contains references to Ghost entities. The checks that verify the
473 -- proper use of a Ghost entity need to know the enclosing context.
477 -- An assignment statement is Ghost when the left hand side denotes a
478 -- Ghost entity. Set the mode now to ensure that any nodes generated
479 -- during analysis and expansion are properly marked as Ghost.
481 if Has_Target_Names
(N
) then
482 Current_Assignment
:= N
;
483 Expander_Mode_Save_And_Set
(False);
484 Save_Full_Analysis
:= Full_Analysis
;
485 Full_Analysis
:= False;
487 Current_Assignment
:= Empty
;
490 Mark_And_Set_Ghost_Assignment
(N
);
493 -- Ensure that we never do an assignment on a variable marked as
494 -- Is_Safe_To_Reevaluate.
497 (not Is_Entity_Name
(Lhs
)
498 or else Ekind
(Entity
(Lhs
)) /= E_Variable
499 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
501 -- Start type analysis for assignment
505 -- In the most general case, both Lhs and Rhs can be overloaded, and we
506 -- must compute the intersection of the possible types on each side.
508 if Is_Overloaded
(Lhs
) then
515 Get_First_Interp
(Lhs
, I
, It
);
517 while Present
(It
.Typ
) loop
519 -- An indexed component with generalized indexing is always
520 -- overloaded with the corresponding dereference. Discard the
521 -- interpretation that yields a reference type, which is not
524 if Nkind
(Lhs
) = N_Indexed_Component
525 and then Present
(Generalized_Indexing
(Lhs
))
526 and then Has_Implicit_Dereference
(It
.Typ
)
530 -- This may be a call to a parameterless function through an
531 -- implicit dereference, so discard interpretation as well.
533 elsif Is_Entity_Name
(Lhs
)
534 and then Has_Implicit_Dereference
(It
.Typ
)
538 elsif Has_Compatible_Type
(Rhs
, It
.Typ
) then
539 if T1
= Any_Type
then
542 -- An explicit dereference is overloaded if the prefix
543 -- is. Try to remove the ambiguity on the prefix, the
544 -- error will be posted there if the ambiguity is real.
546 if Nkind
(Lhs
) = N_Explicit_Dereference
then
549 PI1
: Interp_Index
:= 0;
555 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
557 while Present
(PIt
.Typ
) loop
558 if Is_Access_Type
(PIt
.Typ
)
559 and then Has_Compatible_Type
560 (Rhs
, Designated_Type
(PIt
.Typ
))
564 Disambiguate
(Prefix
(Lhs
),
567 if PIt
= No_Interp
then
569 ("ambiguous left-hand side in "
570 & "assignment", Lhs
);
573 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
583 Get_Next_Interp
(PI
, PIt
);
589 ("ambiguous left-hand side in assignment", Lhs
);
595 Get_Next_Interp
(I
, It
);
599 if T1
= Any_Type
then
601 ("no valid types for left-hand side for assignment", Lhs
);
607 -- Deal with build-in-place calls for nonlimited types. We don't do this
608 -- later, because resolving the rhs tranforms it incorrectly for build-
611 if Should_Transform_BIP_Assignment
(Typ
=> T1
) then
613 -- In certain cases involving user-defined concatenation operators,
614 -- we need to resolve the right-hand side before transforming the
617 case Nkind
(Unqual_Conv
(Rhs
)) is
618 when N_Function_Call
=>
621 First
(Parameter_Associations
(Unqual_Conv
(Rhs
)));
622 Actual_Exp
: Node_Id
;
625 while Present
(Actual
) loop
626 if Nkind
(Actual
) = N_Parameter_Association
then
627 Actual_Exp
:= Explicit_Actual_Parameter
(Actual
);
629 Actual_Exp
:= Actual
;
632 if Nkind
(Actual_Exp
) = N_Op_Concat
then
641 when N_Attribute_Reference
652 Transform_BIP_Assignment
(Typ
=> T1
);
655 pragma Assert
(not Should_Transform_BIP_Assignment
(Typ
=> T1
));
657 -- The resulting assignment type is T1, so now we will resolve the left
658 -- hand side of the assignment using this determined type.
662 -- Cases where Lhs is not a variable. In an instance or an inlined body
663 -- no need for further check because assignment was legal in template.
665 if In_Inlined_Body
then
668 elsif not Is_Variable
(Lhs
) then
670 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
678 if Ada_Version
>= Ada_2005
then
680 -- Handle chains of renamings
683 while Nkind
(Ent
) in N_Has_Entity
684 and then Present
(Entity
(Ent
))
685 and then Present
(Renamed_Object
(Entity
(Ent
)))
687 Ent
:= Renamed_Object
(Entity
(Ent
));
690 if (Nkind
(Ent
) = N_Attribute_Reference
691 and then Attribute_Name
(Ent
) = Name_Priority
)
693 -- Renamings of the attribute Priority applied to protected
694 -- objects have been previously expanded into calls to the
695 -- Get_Ceiling run-time subprogram.
697 or else Is_Expanded_Priority_Attribute
(Ent
)
699 -- The enclosing subprogram cannot be a protected function
702 while not (Is_Subprogram
(S
)
703 and then Convention
(S
) = Convention_Protected
)
704 and then S
/= Standard_Standard
709 if Ekind
(S
) = E_Function
710 and then Convention
(S
) = Convention_Protected
713 ("protected function cannot modify protected object",
717 -- Changes of the ceiling priority of the protected object
718 -- are only effective if the Ceiling_Locking policy is in
719 -- effect (AARM D.5.2 (5/2)).
721 if Locking_Policy
/= 'C' then
723 ("assignment to the attribute PRIORITY has no effect??",
726 ("\since no Locking_Policy has been specified??", Lhs
);
734 Diagnose_Non_Variable_Lhs
(Lhs
);
737 -- Error of assigning to limited type. We do however allow this in
738 -- certain cases where the front end generates the assignments.
740 elsif Is_Limited_Type
(T1
)
741 and then not Assignment_OK
(Lhs
)
742 and then not Assignment_OK
(Original_Node
(Lhs
))
744 -- CPP constructors can only be called in declarations
746 if Is_CPP_Constructor_Call
(Rhs
) then
747 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
750 ("left hand of assignment must not be limited type", Lhs
);
751 Explain_Limited_Type
(T1
, Lhs
);
756 -- A class-wide type may be a limited view. This illegal case is not
757 -- caught by previous checks.
759 elsif Ekind
(T1
) = E_Class_Wide_Type
and then From_Limited_With
(T1
) then
760 Error_Msg_NE
("invalid use of limited view of&", Lhs
, T1
);
763 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
764 -- abstract. This is only checked when the assignment Comes_From_Source,
765 -- because in some cases the expander generates such assignments (such
766 -- in the _assign operation for an abstract type).
768 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
770 ("target of assignment operation must not be abstract", Lhs
);
773 -- Variables which are Part_Of constituents of single protected types
774 -- behave in similar fashion to protected components. Such variables
775 -- cannot be modified by protected functions.
777 if Is_Protected_Part_Of_Constituent
(Lhs
) and then Within_Function
then
779 ("protected function cannot modify protected object", Lhs
);
782 -- Resolution may have updated the subtype, in case the left-hand side
783 -- is a private protected component. Use the correct subtype to avoid
784 -- scoping issues in the back-end.
788 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
789 -- type. For example:
793 -- type Acc is access P.T;
796 -- with Pkg; use Acc;
797 -- procedure Example is
800 -- A.all := B.all; -- ERROR
803 if Nkind
(Lhs
) = N_Explicit_Dereference
804 and then Ekind
(T1
) = E_Incomplete_Type
806 Error_Msg_N
("invalid use of incomplete type", Lhs
);
811 -- Now we can complete the resolution of the right hand side
813 Set_Assignment_Type
(Lhs
, T1
);
815 -- If the target of the assignment is an entity of a mutable type and
816 -- the expression is a conditional expression, its alternatives can be
817 -- of different subtypes of the nominal type of the LHS, so they must be
818 -- resolved with the base type, given that their subtype may differ from
819 -- that of the target mutable object.
821 if Is_Entity_Name
(Lhs
)
822 and then Ekind_In
(Entity
(Lhs
), E_In_Out_Parameter
,
825 and then Is_Composite_Type
(T1
)
826 and then not Is_Constrained
(Etype
(Entity
(Lhs
)))
827 and then Nkind_In
(Rhs
, N_If_Expression
, N_Case_Expression
)
829 Resolve
(Rhs
, Base_Type
(T1
));
835 -- This is the point at which we check for an unset reference
837 Check_Unset_Reference
(Rhs
);
838 Check_Unprotected_Access
(Lhs
, Rhs
);
840 -- Remaining steps are skipped if Rhs was syntactically in error
849 if not Covers
(T1
, T2
) then
850 Wrong_Type
(Rhs
, Etype
(Lhs
));
855 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
856 -- types, use the non-limited view if available
858 if Nkind
(Rhs
) = N_Explicit_Dereference
859 and then Is_Tagged_Type
(T2
)
860 and then Has_Non_Limited_View
(T2
)
862 T2
:= Non_Limited_View
(T2
);
865 Set_Assignment_Type
(Rhs
, T2
);
867 if Total_Errors_Detected
/= 0 then
877 if T1
= Any_Type
or else T2
= Any_Type
then
882 -- If the rhs is class-wide or dynamically tagged, then require the lhs
883 -- to be class-wide. The case where the rhs is a dynamically tagged call
884 -- to a dispatching operation with a controlling access result is
885 -- excluded from this check, since the target has an access type (and
886 -- no tag propagation occurs in that case).
888 if (Is_Class_Wide_Type
(T2
)
889 or else (Is_Dynamically_Tagged
(Rhs
)
890 and then not Is_Access_Type
(T1
)))
891 and then not Is_Class_Wide_Type
(T1
)
893 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
895 elsif Is_Class_Wide_Type
(T1
)
896 and then not Is_Class_Wide_Type
(T2
)
897 and then not Is_Tag_Indeterminate
(Rhs
)
898 and then not Is_Dynamically_Tagged
(Rhs
)
900 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
903 -- Propagate the tag from a class-wide target to the rhs when the rhs
904 -- is a tag-indeterminate call.
906 if Is_Tag_Indeterminate
(Rhs
) then
907 if Is_Class_Wide_Type
(T1
) then
908 Propagate_Tag
(Lhs
, Rhs
);
910 elsif Nkind
(Rhs
) = N_Function_Call
911 and then Is_Entity_Name
(Name
(Rhs
))
912 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
915 ("call to abstract function must be dispatching", Name
(Rhs
));
917 elsif Nkind
(Rhs
) = N_Qualified_Expression
918 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
919 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
921 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
924 ("call to abstract function must be dispatching",
925 Name
(Expression
(Rhs
)));
929 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
930 -- apply an implicit conversion of the rhs to that type to force
931 -- appropriate static and run-time accessibility checks. This applies
932 -- as well to anonymous access-to-subprogram types that are component
933 -- subtypes or formal parameters.
935 if Ada_Version
>= Ada_2005
and then Is_Access_Type
(T1
) then
936 if Is_Local_Anonymous_Access
(T1
)
937 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
939 -- Handle assignment to an Ada 2012 stand-alone object
940 -- of an anonymous access type.
942 or else (Ekind
(T1
) = E_Anonymous_Access_Type
943 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
944 N_Object_Declaration
)
947 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
948 Analyze_And_Resolve
(Rhs
, T1
);
952 -- Ada 2005 (AI-231): Assignment to not null variable
954 if Ada_Version
>= Ada_2005
955 and then Can_Never_Be_Null
(T1
)
956 and then not Assignment_OK
(Lhs
)
958 -- Case where we know the right hand side is null
960 if Known_Null
(Rhs
) then
961 Apply_Compile_Time_Constraint_Error
964 "(Ada 2005) null not allowed in null-excluding objects??",
965 Reason
=> CE_Null_Not_Allowed
);
967 -- We still mark this as a possible modification, that's necessary
968 -- to reset Is_True_Constant, and desirable for xref purposes.
970 Note_Possible_Modification
(Lhs
, Sure
=> True);
973 -- If we know the right hand side is non-null, then we convert to the
974 -- target type, since we don't need a run time check in that case.
976 elsif not Can_Never_Be_Null
(T2
) then
977 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
978 Analyze_And_Resolve
(Rhs
, T1
);
982 if Is_Scalar_Type
(T1
) then
983 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
985 -- For array types, verify that lengths match. If the right hand side
986 -- is a function call that has been inlined, the assignment has been
987 -- rewritten as a block, and the constraint check will be applied to the
988 -- assignment within the block.
990 elsif Is_Array_Type
(T1
)
991 and then (Nkind
(Rhs
) /= N_Type_Conversion
992 or else Is_Constrained
(Etype
(Rhs
)))
993 and then (Nkind
(Rhs
) /= N_Function_Call
994 or else Nkind
(N
) /= N_Block_Statement
)
996 -- Assignment verifies that the length of the Lsh and Rhs are equal,
997 -- but of course the indexes do not have to match. If the right-hand
998 -- side is a type conversion to an unconstrained type, a length check
999 -- is performed on the expression itself during expansion. In rare
1000 -- cases, the redundant length check is computed on an index type
1001 -- with a different representation, triggering incorrect code in the
1004 Apply_Length_Check
(Rhs
, Etype
(Lhs
));
1007 -- Discriminant checks are applied in the course of expansion
1012 -- Note: modifications of the Lhs may only be recorded after
1013 -- checks have been applied.
1015 Note_Possible_Modification
(Lhs
, Sure
=> True);
1017 -- ??? a real accessibility check is needed when ???
1019 -- Post warning for redundant assignment or variable to itself
1021 if Warn_On_Redundant_Constructs
1023 -- We only warn for source constructs
1025 and then Comes_From_Source
(N
)
1027 -- Where the object is the same on both sides
1029 and then Same_Object
(Lhs
, Original_Node
(Rhs
))
1031 -- But exclude the case where the right side was an operation that
1032 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
1033 -- don't want to warn in such a case, since it is reasonable to write
1034 -- such expressions especially when K is defined symbolically in some
1037 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
1039 if Nkind
(Lhs
) in N_Has_Entity
then
1040 Error_Msg_NE
-- CODEFIX
1041 ("?r?useless assignment of & to itself!", N
, Entity
(Lhs
));
1043 Error_Msg_N
-- CODEFIX
1044 ("?r?useless assignment of object to itself!", N
);
1048 -- Check for non-allowed composite assignment
1050 if not Support_Composite_Assign_On_Target
1051 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
1052 and then (not Has_Size_Clause
(T1
) or else Esize
(T1
) > 64)
1054 Error_Msg_CRT
("composite assignment", N
);
1057 -- Check elaboration warning for left side if not in elab code
1059 if Legacy_Elaboration_Checks
1060 and not In_Subprogram_Or_Concurrent_Unit
1062 Check_Elab_Assign
(Lhs
);
1065 -- Save the scenario for later examination by the ABE Processing phase
1067 Record_Elaboration_Scenario
(N
);
1069 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
1070 -- assignment is a source assignment in the extended main source unit.
1071 -- We are not interested in any reference information outside this
1072 -- context, or in compiler generated assignment statements.
1074 if Comes_From_Source
(N
)
1075 and then In_Extended_Main_Source_Unit
(Lhs
)
1077 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
1080 -- RM 7.3.2 (12/3): An assignment to a view conversion (from a type to
1081 -- one of its ancestors) requires an invariant check. Apply check only
1082 -- if expression comes from source, otherwise it will be applied when
1083 -- value is assigned to source entity. This is not done in GNATprove
1084 -- mode, as GNATprove handles invariant checks itself.
1086 if Nkind
(Lhs
) = N_Type_Conversion
1087 and then Has_Invariants
(Etype
(Expression
(Lhs
)))
1088 and then Comes_From_Source
(Expression
(Lhs
))
1089 and then not GNATprove_Mode
1091 Insert_After
(N
, Make_Invariant_Call
(Expression
(Lhs
)));
1094 -- Final step. If left side is an entity, then we may be able to reset
1095 -- the current tracked values to new safe values. We only have something
1096 -- to do if the left side is an entity name, and expansion has not
1097 -- modified the node into something other than an assignment, and of
1098 -- course we only capture values if it is safe to do so.
1100 if Is_Entity_Name
(Lhs
)
1101 and then Nkind
(N
) = N_Assignment_Statement
1104 Ent
: constant Entity_Id
:= Entity
(Lhs
);
1107 if Safe_To_Capture_Value
(N
, Ent
) then
1109 -- If simple variable on left side, warn if this assignment
1110 -- blots out another one (rendering it useless). We only do
1111 -- this for source assignments, otherwise we can generate bogus
1112 -- warnings when an assignment is rewritten as another
1113 -- assignment, and gets tied up with itself.
1115 -- There may have been a previous reference to a component of
1116 -- the variable, which in general removes the Last_Assignment
1117 -- field of the variable to indicate a relevant use of the
1118 -- previous assignment. However, if the assignment is to a
1119 -- subcomponent the reference may not have registered, because
1120 -- it is not possible to determine whether the context is an
1121 -- assignment. In those cases we generate a Deferred_Reference,
1122 -- to be used at the end of compilation to generate the right
1123 -- kind of reference, and we suppress a potential warning for
1124 -- a useless assignment, which might be premature. This may
1125 -- lose a warning in rare cases, but seems preferable to a
1126 -- misleading warning.
1128 if Warn_On_Modified_Unread
1129 and then Is_Assignable
(Ent
)
1130 and then Comes_From_Source
(N
)
1131 and then In_Extended_Main_Source_Unit
(Ent
)
1132 and then not Has_Deferred_Reference
(Ent
)
1134 Warn_On_Useless_Assignment
(Ent
, N
);
1137 -- If we are assigning an access type and the left side is an
1138 -- entity, then make sure that the Is_Known_[Non_]Null flags
1139 -- properly reflect the state of the entity after assignment.
1141 if Is_Access_Type
(T1
) then
1142 if Known_Non_Null
(Rhs
) then
1143 Set_Is_Known_Non_Null
(Ent
, True);
1145 elsif Known_Null
(Rhs
)
1146 and then not Can_Never_Be_Null
(Ent
)
1148 Set_Is_Known_Null
(Ent
, True);
1151 Set_Is_Known_Null
(Ent
, False);
1153 if not Can_Never_Be_Null
(Ent
) then
1154 Set_Is_Known_Non_Null
(Ent
, False);
1158 -- For discrete types, we may be able to set the current value
1159 -- if the value is known at compile time.
1161 elsif Is_Discrete_Type
(T1
)
1162 and then Compile_Time_Known_Value
(Rhs
)
1164 Set_Current_Value
(Ent
, Rhs
);
1166 Set_Current_Value
(Ent
, Empty
);
1169 -- If not safe to capture values, kill them
1177 -- If assigning to an object in whole or in part, note location of
1178 -- assignment in case no one references value. We only do this for
1179 -- source assignments, otherwise we can generate bogus warnings when an
1180 -- assignment is rewritten as another assignment, and gets tied up with
1184 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
1187 and then Safe_To_Capture_Value
(N
, Ent
)
1188 and then Nkind
(N
) = N_Assignment_Statement
1189 and then Warn_On_Modified_Unread
1190 and then Is_Assignable
(Ent
)
1191 and then Comes_From_Source
(N
)
1192 and then In_Extended_Main_Source_Unit
(Ent
)
1194 Set_Last_Assignment
(Ent
, Lhs
);
1198 Analyze_Dimension
(N
);
1201 Restore_Ghost_Region
(Saved_GM
, Saved_IGR
);
1203 -- If the right-hand side contains target names, expansion has been
1204 -- disabled to prevent expansion that might move target names out of
1205 -- the context of the assignment statement. Restore the expander mode
1206 -- now so that assignment statement can be properly expanded.
1208 if Nkind
(N
) = N_Assignment_Statement
then
1209 if Has_Target_Names
(N
) then
1210 Expander_Mode_Restore
;
1211 Full_Analysis
:= Save_Full_Analysis
;
1214 pragma Assert
(not Should_Transform_BIP_Assignment
(Typ
=> T1
));
1216 end Analyze_Assignment
;
1218 -----------------------------
1219 -- Analyze_Block_Statement --
1220 -----------------------------
1222 procedure Analyze_Block_Statement
(N
: Node_Id
) is
1223 procedure Install_Return_Entities
(Scop
: Entity_Id
);
1224 -- Install all entities of return statement scope Scop in the visibility
1225 -- chain except for the return object since its entity is reused in a
1228 -----------------------------
1229 -- Install_Return_Entities --
1230 -----------------------------
1232 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
1236 Id
:= First_Entity
(Scop
);
1237 while Present
(Id
) loop
1239 -- Do not install the return object
1241 if not Ekind_In
(Id
, E_Constant
, E_Variable
)
1242 or else not Is_Return_Object
(Id
)
1244 Install_Entity
(Id
);
1249 end Install_Return_Entities
;
1251 -- Local constants and variables
1253 Decls
: constant List_Id
:= Declarations
(N
);
1254 Id
: constant Node_Id
:= Identifier
(N
);
1255 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
1257 Is_BIP_Return_Statement
: Boolean;
1259 -- Start of processing for Analyze_Block_Statement
1262 -- In SPARK mode, we reject block statements. Note that the case of
1263 -- block statements generated by the expander is fine.
1265 if Nkind
(Original_Node
(N
)) = N_Block_Statement
then
1266 Check_SPARK_05_Restriction
("block statement is not allowed", N
);
1269 -- If no handled statement sequence is present, things are really messed
1270 -- up, and we just return immediately (defence against previous errors).
1273 Check_Error_Detected
;
1277 -- Detect whether the block is actually a rewritten return statement of
1278 -- a build-in-place function.
1280 Is_BIP_Return_Statement
:=
1282 and then Present
(Entity
(Id
))
1283 and then Ekind
(Entity
(Id
)) = E_Return_Statement
1284 and then Is_Build_In_Place_Function
1285 (Return_Applies_To
(Entity
(Id
)));
1287 -- Normal processing with HSS present
1290 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
1291 Ent
: Entity_Id
:= Empty
;
1294 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1295 -- Recursively save value of this global, will be restored on exit
1298 -- Initialize unblocked exit count for statements of begin block
1299 -- plus one for each exception handler that is present.
1301 Unblocked_Exit_Count
:= 1;
1303 if Present
(EH
) then
1304 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ List_Length
(EH
);
1307 -- If a label is present analyze it and mark it as referenced
1309 if Present
(Id
) then
1313 -- An error defense. If we have an identifier, but no entity, then
1314 -- something is wrong. If previous errors, then just remove the
1315 -- identifier and continue, otherwise raise an exception.
1318 Check_Error_Detected
;
1319 Set_Identifier
(N
, Empty
);
1322 Set_Ekind
(Ent
, E_Block
);
1323 Generate_Reference
(Ent
, N
, ' ');
1324 Generate_Definition
(Ent
);
1326 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
1327 Set_Label_Construct
(Parent
(Ent
), N
);
1332 -- If no entity set, create a label entity
1335 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
1336 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
1337 Set_Parent
(Ent
, N
);
1340 Set_Etype
(Ent
, Standard_Void_Type
);
1341 Set_Block_Node
(Ent
, Identifier
(N
));
1344 -- The block served as an extended return statement. Ensure that any
1345 -- entities created during the analysis and expansion of the return
1346 -- object declaration are once again visible.
1348 if Is_BIP_Return_Statement
then
1349 Install_Return_Entities
(Ent
);
1352 if Present
(Decls
) then
1353 Analyze_Declarations
(Decls
);
1355 Inspect_Deferred_Constant_Completion
(Decls
);
1359 Process_End_Label
(HSS
, 'e', Ent
);
1361 -- If exception handlers are present, then we indicate that enclosing
1362 -- scopes contain a block with handlers. We only need to mark non-
1365 if Present
(EH
) then
1368 Set_Has_Nested_Block_With_Handler
(S
);
1369 exit when Is_Overloadable
(S
)
1370 or else Ekind
(S
) = E_Package
1371 or else Is_Generic_Unit
(S
);
1376 Check_References
(Ent
);
1377 Update_Use_Clause_Chain
;
1380 if Unblocked_Exit_Count
= 0 then
1381 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1382 Check_Unreachable_Code
(N
);
1384 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1387 end Analyze_Block_Statement
;
1389 --------------------------------
1390 -- Analyze_Compound_Statement --
1391 --------------------------------
1393 procedure Analyze_Compound_Statement
(N
: Node_Id
) is
1395 Analyze_List
(Actions
(N
));
1396 end Analyze_Compound_Statement
;
1398 ----------------------------
1399 -- Analyze_Case_Statement --
1400 ----------------------------
1402 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1404 Exp_Type
: Entity_Id
;
1405 Exp_Btype
: Entity_Id
;
1408 Others_Present
: Boolean;
1409 -- Indicates if Others was present
1411 pragma Warnings
(Off
, Last_Choice
);
1412 -- Don't care about assigned value
1414 Statements_Analyzed
: Boolean := False;
1415 -- Set True if at least some statement sequences get analyzed. If False
1416 -- on exit, means we had a serious error that prevented full analysis of
1417 -- the case statement, and as a result it is not a good idea to output
1418 -- warning messages about unreachable code.
1420 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1421 -- Recursively save value of this global, will be restored on exit
1423 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1424 -- Error routine invoked by the generic instantiation below when the
1425 -- case statement has a non static choice.
1427 procedure Process_Statements
(Alternative
: Node_Id
);
1428 -- Analyzes the statements associated with a case alternative. Needed
1429 -- by instantiation below.
1431 package Analyze_Case_Choices
is new
1432 Generic_Analyze_Choices
1433 (Process_Associated_Node
=> Process_Statements
);
1434 use Analyze_Case_Choices
;
1435 -- Instantiation of the generic choice analysis package
1437 package Check_Case_Choices
is new
1438 Generic_Check_Choices
1439 (Process_Empty_Choice
=> No_OP
,
1440 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1441 Process_Associated_Node
=> No_OP
);
1442 use Check_Case_Choices
;
1443 -- Instantiation of the generic choice processing package
1445 -----------------------------
1446 -- Non_Static_Choice_Error --
1447 -----------------------------
1449 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1451 Flag_Non_Static_Expr
1452 ("choice given in case statement is not static!", Choice
);
1453 end Non_Static_Choice_Error
;
1455 ------------------------
1456 -- Process_Statements --
1457 ------------------------
1459 procedure Process_Statements
(Alternative
: Node_Id
) is
1460 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1464 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1465 Statements_Analyzed
:= True;
1467 -- An interesting optimization. If the case statement expression
1468 -- is a simple entity, then we can set the current value within an
1469 -- alternative if the alternative has one possible value.
1473 -- when 2 | 3 => beta
1474 -- when others => gamma
1476 -- Here we know that N is initially 1 within alpha, but for beta and
1477 -- gamma, we do not know anything more about the initial value.
1479 if Is_Entity_Name
(Exp
) then
1480 Ent
:= Entity
(Exp
);
1482 if Ekind_In
(Ent
, E_Variable
,
1486 if List_Length
(Choices
) = 1
1487 and then Nkind
(First
(Choices
)) in N_Subexpr
1488 and then Compile_Time_Known_Value
(First
(Choices
))
1490 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1493 Analyze_Statements
(Statements
(Alternative
));
1495 -- After analyzing the case, set the current value to empty
1496 -- since we won't know what it is for the next alternative
1497 -- (unless reset by this same circuit), or after the case.
1499 Set_Current_Value
(Entity
(Exp
), Empty
);
1504 -- Case where expression is not an entity name of a variable
1506 Analyze_Statements
(Statements
(Alternative
));
1507 end Process_Statements
;
1509 -- Start of processing for Analyze_Case_Statement
1512 Unblocked_Exit_Count
:= 0;
1513 Exp
:= Expression
(N
);
1516 -- The expression must be of any discrete type. In rare cases, the
1517 -- expander constructs a case statement whose expression has a private
1518 -- type whose full view is discrete. This can happen when generating
1519 -- a stream operation for a variant type after the type is frozen,
1520 -- when the partial of view of the type of the discriminant is private.
1521 -- In that case, use the full view to analyze case alternatives.
1523 if not Is_Overloaded
(Exp
)
1524 and then not Comes_From_Source
(N
)
1525 and then Is_Private_Type
(Etype
(Exp
))
1526 and then Present
(Full_View
(Etype
(Exp
)))
1527 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1529 Resolve
(Exp
, Etype
(Exp
));
1530 Exp_Type
:= Full_View
(Etype
(Exp
));
1533 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1534 Exp_Type
:= Etype
(Exp
);
1537 Check_Unset_Reference
(Exp
);
1538 Exp_Btype
:= Base_Type
(Exp_Type
);
1540 -- The expression must be of a discrete type which must be determinable
1541 -- independently of the context in which the expression occurs, but
1542 -- using the fact that the expression must be of a discrete type.
1543 -- Moreover, the type this expression must not be a character literal
1544 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1546 -- If error already reported by Resolve, nothing more to do
1548 if Exp_Btype
= Any_Discrete
or else Exp_Btype
= Any_Type
then
1551 elsif Exp_Btype
= Any_Character
then
1553 ("character literal as case expression is ambiguous", Exp
);
1556 elsif Ada_Version
= Ada_83
1557 and then (Is_Generic_Type
(Exp_Btype
)
1558 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1561 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1565 -- If the case expression is a formal object of mode in out, then treat
1566 -- it as having a nonstatic subtype by forcing use of the base type
1567 -- (which has to get passed to Check_Case_Choices below). Also use base
1568 -- type when the case expression is parenthesized.
1570 if Paren_Count
(Exp
) > 0
1571 or else (Is_Entity_Name
(Exp
)
1572 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1574 Exp_Type
:= Exp_Btype
;
1577 -- Call instantiated procedures to analyzwe and check discrete choices
1579 Analyze_Choices
(Alternatives
(N
), Exp_Type
);
1580 Check_Choices
(N
, Alternatives
(N
), Exp_Type
, Others_Present
);
1582 -- Case statement with single OTHERS alternative not allowed in SPARK
1584 if Others_Present
and then List_Length
(Alternatives
(N
)) = 1 then
1585 Check_SPARK_05_Restriction
1586 ("OTHERS as unique case alternative is not allowed", N
);
1589 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1590 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1593 -- If all our exits were blocked by unconditional transfers of control,
1594 -- then the entire CASE statement acts as an unconditional transfer of
1595 -- control, so treat it like one, and check unreachable code. Skip this
1596 -- test if we had serious errors preventing any statement analysis.
1598 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1599 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1600 Check_Unreachable_Code
(N
);
1602 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1605 -- If the expander is active it will detect the case of a statically
1606 -- determined single alternative and remove warnings for the case, but
1607 -- if we are not doing expansion, that circuit won't be active. Here we
1608 -- duplicate the effect of removing warnings in the same way, so that
1609 -- we will get the same set of warnings in -gnatc mode.
1611 if not Expander_Active
1612 and then Compile_Time_Known_Value
(Expression
(N
))
1613 and then Serious_Errors_Detected
= 0
1616 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1620 Alt
:= First
(Alternatives
(N
));
1621 while Present
(Alt
) loop
1622 if Alt
/= Chosen
then
1623 Remove_Warning_Messages
(Statements
(Alt
));
1630 end Analyze_Case_Statement
;
1632 ----------------------------
1633 -- Analyze_Exit_Statement --
1634 ----------------------------
1636 -- If the exit includes a name, it must be the name of a currently open
1637 -- loop. Otherwise there must be an innermost open loop on the stack, to
1638 -- which the statement implicitly refers.
1640 -- Additionally, in SPARK mode:
1642 -- The exit can only name the closest enclosing loop;
1644 -- An exit with a when clause must be directly contained in a loop;
1646 -- An exit without a when clause must be directly contained in an
1647 -- if-statement with no elsif or else, which is itself directly contained
1648 -- in a loop. The exit must be the last statement in the if-statement.
1650 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1651 Target
: constant Node_Id
:= Name
(N
);
1652 Cond
: constant Node_Id
:= Condition
(N
);
1653 Scope_Id
: Entity_Id
:= Empty
; -- initialize to prevent warning
1659 Check_Unreachable_Code
(N
);
1662 if Present
(Target
) then
1664 U_Name
:= Entity
(Target
);
1666 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1667 Error_Msg_N
("invalid loop name in exit statement", N
);
1671 if Has_Loop_In_Inner_Open_Scopes
(U_Name
) then
1672 Check_SPARK_05_Restriction
1673 ("exit label must name the closest enclosing loop", N
);
1676 Set_Has_Exit
(U_Name
);
1683 for J
in reverse 0 .. Scope_Stack
.Last
loop
1684 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1685 Kind
:= Ekind
(Scope_Id
);
1687 if Kind
= E_Loop
and then (No
(Target
) or else Scope_Id
= U_Name
) then
1688 Set_Has_Exit
(Scope_Id
);
1691 elsif Kind
= E_Block
1692 or else Kind
= E_Loop
1693 or else Kind
= E_Return_Statement
1699 ("cannot exit from program unit or accept statement", N
);
1704 -- Verify that if present the condition is a Boolean expression
1706 if Present
(Cond
) then
1707 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1708 Check_Unset_Reference
(Cond
);
1711 -- In SPARK mode, verify that the exit statement respects the SPARK
1714 if Present
(Cond
) then
1715 if Nkind
(Parent
(N
)) /= N_Loop_Statement
then
1716 Check_SPARK_05_Restriction
1717 ("exit with when clause must be directly in loop", N
);
1721 if Nkind
(Parent
(N
)) /= N_If_Statement
then
1722 if Nkind
(Parent
(N
)) = N_Elsif_Part
then
1723 Check_SPARK_05_Restriction
1724 ("exit must be in IF without ELSIF", N
);
1726 Check_SPARK_05_Restriction
("exit must be directly in IF", N
);
1729 elsif Nkind
(Parent
(Parent
(N
))) /= N_Loop_Statement
then
1730 Check_SPARK_05_Restriction
1731 ("exit must be in IF directly in loop", N
);
1733 -- First test the presence of ELSE, so that an exit in an ELSE leads
1734 -- to an error mentioning the ELSE.
1736 elsif Present
(Else_Statements
(Parent
(N
))) then
1737 Check_SPARK_05_Restriction
("exit must be in IF without ELSE", N
);
1739 -- An exit in an ELSIF does not reach here, as it would have been
1740 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1742 elsif Present
(Elsif_Parts
(Parent
(N
))) then
1743 Check_SPARK_05_Restriction
("exit must be in IF without ELSIF", N
);
1747 -- Chain exit statement to associated loop entity
1749 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1750 Set_First_Exit_Statement
(Scope_Id
, N
);
1752 -- Since the exit may take us out of a loop, any previous assignment
1753 -- statement is not useless, so clear last assignment indications. It
1754 -- is OK to keep other current values, since if the exit statement
1755 -- does not exit, then the current values are still valid.
1757 Kill_Current_Values
(Last_Assignment_Only
=> True);
1758 end Analyze_Exit_Statement
;
1760 ----------------------------
1761 -- Analyze_Goto_Statement --
1762 ----------------------------
1764 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1765 Label
: constant Node_Id
:= Name
(N
);
1766 Scope_Id
: Entity_Id
;
1767 Label_Scope
: Entity_Id
;
1768 Label_Ent
: Entity_Id
;
1771 Check_SPARK_05_Restriction
("goto statement is not allowed", N
);
1773 -- Actual semantic checks
1775 Check_Unreachable_Code
(N
);
1776 Kill_Current_Values
(Last_Assignment_Only
=> True);
1779 Label_Ent
:= Entity
(Label
);
1781 -- Ignore previous error
1783 if Label_Ent
= Any_Id
then
1784 Check_Error_Detected
;
1787 -- We just have a label as the target of a goto
1789 elsif Ekind
(Label_Ent
) /= E_Label
then
1790 Error_Msg_N
("target of goto statement must be a label", Label
);
1793 -- Check that the target of the goto is reachable according to Ada
1794 -- scoping rules. Note: the special gotos we generate for optimizing
1795 -- local handling of exceptions would violate these rules, but we mark
1796 -- such gotos as analyzed when built, so this code is never entered.
1798 elsif not Reachable
(Label_Ent
) then
1799 Error_Msg_N
("target of goto statement is not reachable", Label
);
1803 -- Here if goto passes initial validity checks
1805 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1807 for J
in reverse 0 .. Scope_Stack
.Last
loop
1808 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1810 if Label_Scope
= Scope_Id
1811 or else not Ekind_In
(Scope_Id
, E_Block
, E_Loop
, E_Return_Statement
)
1813 if Scope_Id
/= Label_Scope
then
1815 ("cannot exit from program unit or accept statement", N
);
1822 raise Program_Error
;
1823 end Analyze_Goto_Statement
;
1825 --------------------------
1826 -- Analyze_If_Statement --
1827 --------------------------
1829 -- A special complication arises in the analysis of if statements
1831 -- The expander has circuitry to completely delete code that it can tell
1832 -- will not be executed (as a result of compile time known conditions). In
1833 -- the analyzer, we ensure that code that will be deleted in this manner
1834 -- is analyzed but not expanded. This is obviously more efficient, but
1835 -- more significantly, difficulties arise if code is expanded and then
1836 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1837 -- generated in deleted code must be frozen from start, because the nodes
1838 -- on which they depend will not be available at the freeze point.
1840 procedure Analyze_If_Statement
(N
: Node_Id
) is
1843 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1844 -- Recursively save value of this global, will be restored on exit
1846 Save_In_Deleted_Code
: Boolean;
1848 Del
: Boolean := False;
1849 -- This flag gets set True if a True condition has been found, which
1850 -- means that remaining ELSE/ELSIF parts are deleted.
1852 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1853 -- This is applied to either the N_If_Statement node itself or to an
1854 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1855 -- statements associated with it.
1857 -----------------------
1858 -- Analyze_Cond_Then --
1859 -----------------------
1861 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1862 Cond
: constant Node_Id
:= Condition
(Cnode
);
1863 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1866 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1867 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1868 Check_Unset_Reference
(Cond
);
1869 Set_Current_Value_Condition
(Cnode
);
1871 -- If already deleting, then just analyze then statements
1874 Analyze_Statements
(Tstm
);
1876 -- Compile time known value, not deleting yet
1878 elsif Compile_Time_Known_Value
(Cond
) then
1879 Save_In_Deleted_Code
:= In_Deleted_Code
;
1881 -- If condition is True, then analyze the THEN statements and set
1882 -- no expansion for ELSE and ELSIF parts.
1884 if Is_True
(Expr_Value
(Cond
)) then
1885 Analyze_Statements
(Tstm
);
1887 Expander_Mode_Save_And_Set
(False);
1888 In_Deleted_Code
:= True;
1890 -- If condition is False, analyze THEN with expansion off
1892 else -- Is_False (Expr_Value (Cond))
1893 Expander_Mode_Save_And_Set
(False);
1894 In_Deleted_Code
:= True;
1895 Analyze_Statements
(Tstm
);
1896 Expander_Mode_Restore
;
1897 In_Deleted_Code
:= Save_In_Deleted_Code
;
1900 -- Not known at compile time, not deleting, normal analysis
1903 Analyze_Statements
(Tstm
);
1905 end Analyze_Cond_Then
;
1907 -- Start of processing for Analyze_If_Statement
1910 -- Initialize exit count for else statements. If there is no else part,
1911 -- this count will stay non-zero reflecting the fact that the uncovered
1912 -- else case is an unblocked exit.
1914 Unblocked_Exit_Count
:= 1;
1915 Analyze_Cond_Then
(N
);
1917 -- Now to analyze the elsif parts if any are present
1919 if Present
(Elsif_Parts
(N
)) then
1920 E
:= First
(Elsif_Parts
(N
));
1921 while Present
(E
) loop
1922 Analyze_Cond_Then
(E
);
1927 if Present
(Else_Statements
(N
)) then
1928 Analyze_Statements
(Else_Statements
(N
));
1931 -- If all our exits were blocked by unconditional transfers of control,
1932 -- then the entire IF statement acts as an unconditional transfer of
1933 -- control, so treat it like one, and check unreachable code.
1935 if Unblocked_Exit_Count
= 0 then
1936 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1937 Check_Unreachable_Code
(N
);
1939 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1943 Expander_Mode_Restore
;
1944 In_Deleted_Code
:= Save_In_Deleted_Code
;
1947 if not Expander_Active
1948 and then Compile_Time_Known_Value
(Condition
(N
))
1949 and then Serious_Errors_Detected
= 0
1951 if Is_True
(Expr_Value
(Condition
(N
))) then
1952 Remove_Warning_Messages
(Else_Statements
(N
));
1954 if Present
(Elsif_Parts
(N
)) then
1955 E
:= First
(Elsif_Parts
(N
));
1956 while Present
(E
) loop
1957 Remove_Warning_Messages
(Then_Statements
(E
));
1963 Remove_Warning_Messages
(Then_Statements
(N
));
1967 -- Warn on redundant if statement that has no effect
1969 -- Note, we could also check empty ELSIF parts ???
1971 if Warn_On_Redundant_Constructs
1973 -- If statement must be from source
1975 and then Comes_From_Source
(N
)
1977 -- Condition must not have obvious side effect
1979 and then Has_No_Obvious_Side_Effects
(Condition
(N
))
1981 -- No elsif parts of else part
1983 and then No
(Elsif_Parts
(N
))
1984 and then No
(Else_Statements
(N
))
1986 -- Then must be a single null statement
1988 and then List_Length
(Then_Statements
(N
)) = 1
1990 -- Go to original node, since we may have rewritten something as
1991 -- a null statement (e.g. a case we could figure the outcome of).
1994 T
: constant Node_Id
:= First
(Then_Statements
(N
));
1995 S
: constant Node_Id
:= Original_Node
(T
);
1998 if Comes_From_Source
(S
) and then Nkind
(S
) = N_Null_Statement
then
1999 Error_Msg_N
("if statement has no effect?r?", N
);
2003 end Analyze_If_Statement
;
2005 ----------------------------------------
2006 -- Analyze_Implicit_Label_Declaration --
2007 ----------------------------------------
2009 -- An implicit label declaration is generated in the innermost enclosing
2010 -- declarative part. This is done for labels, and block and loop names.
2012 -- Note: any changes in this routine may need to be reflected in
2013 -- Analyze_Label_Entity.
2015 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
2016 Id
: constant Node_Id
:= Defining_Identifier
(N
);
2019 Set_Ekind
(Id
, E_Label
);
2020 Set_Etype
(Id
, Standard_Void_Type
);
2021 Set_Enclosing_Scope
(Id
, Current_Scope
);
2022 end Analyze_Implicit_Label_Declaration
;
2024 ------------------------------
2025 -- Analyze_Iteration_Scheme --
2026 ------------------------------
2028 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
2030 Iter_Spec
: Node_Id
;
2031 Loop_Spec
: Node_Id
;
2034 -- For an infinite loop, there is no iteration scheme
2040 Cond
:= Condition
(N
);
2041 Iter_Spec
:= Iterator_Specification
(N
);
2042 Loop_Spec
:= Loop_Parameter_Specification
(N
);
2044 if Present
(Cond
) then
2045 Analyze_And_Resolve
(Cond
, Any_Boolean
);
2046 Check_Unset_Reference
(Cond
);
2047 Set_Current_Value_Condition
(N
);
2049 elsif Present
(Iter_Spec
) then
2050 Analyze_Iterator_Specification
(Iter_Spec
);
2053 Analyze_Loop_Parameter_Specification
(Loop_Spec
);
2055 end Analyze_Iteration_Scheme
;
2057 ------------------------------------
2058 -- Analyze_Iterator_Specification --
2059 ------------------------------------
2061 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
2062 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
2063 Iter_Name
: constant Node_Id
:= Name
(N
);
2064 Loc
: constant Source_Ptr
:= Sloc
(N
);
2065 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
2067 Bas
: Entity_Id
:= Empty
; -- initialize to prevent warning
2070 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
);
2071 -- For an iteration over a container, if the loop carries the Reverse
2072 -- indicator, verify that the container type has an Iterate aspect that
2073 -- implements the reversible iterator interface.
2075 procedure Check_Subtype_Indication
(Comp_Type
: Entity_Id
);
2076 -- If a subtype indication is present, verify that it is consistent
2077 -- with the component type of the array or container name.
2079 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
;
2080 -- For containers with Iterator and related aspects, the cursor is
2081 -- obtained by locating an entity with the proper name in the scope
2084 -----------------------------
2085 -- Check_Reverse_Iteration --
2086 -----------------------------
2088 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
) is
2090 if Reverse_Present
(N
) then
2091 if Is_Array_Type
(Typ
)
2092 or else Is_Reversible_Iterator
(Typ
)
2094 (Present
(Find_Aspect
(Typ
, Aspect_Iterable
))
2097 (Get_Iterable_Type_Primitive
(Typ
, Name_Previous
)))
2102 ("container type does not support reverse iteration", N
, Typ
);
2105 end Check_Reverse_Iteration
;
2107 -------------------------------
2108 -- Check_Subtype_Indication --
2109 -------------------------------
2111 procedure Check_Subtype_Indication
(Comp_Type
: Entity_Id
) is
2114 and then (not Covers
(Base_Type
((Bas
)), Comp_Type
)
2115 or else not Subtypes_Statically_Match
(Bas
, Comp_Type
))
2117 if Is_Array_Type
(Typ
) then
2119 ("subtype indication does not match component type", Subt
);
2122 ("subtype indication does not match element type", Subt
);
2125 end Check_Subtype_Indication
;
2127 ---------------------
2128 -- Get_Cursor_Type --
2129 ---------------------
2131 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
is
2135 -- If iterator type is derived, the cursor is declared in the scope
2136 -- of the parent type.
2138 if Is_Derived_Type
(Typ
) then
2139 Ent
:= First_Entity
(Scope
(Etype
(Typ
)));
2141 Ent
:= First_Entity
(Scope
(Typ
));
2144 while Present
(Ent
) loop
2145 exit when Chars
(Ent
) = Name_Cursor
;
2153 -- The cursor is the target of generated assignments in the
2154 -- loop, and cannot have a limited type.
2156 if Is_Limited_Type
(Etype
(Ent
)) then
2157 Error_Msg_N
("cursor type cannot be limited", N
);
2161 end Get_Cursor_Type
;
2163 -- Start of processing for Analyze_Iterator_Specification
2166 Enter_Name
(Def_Id
);
2168 -- AI12-0151 specifies that when the subtype indication is present, it
2169 -- must statically match the type of the array or container element.
2170 -- To simplify this check, we introduce a subtype declaration with the
2171 -- given subtype indication when it carries a constraint, and rewrite
2172 -- the original as a reference to the created subtype entity.
2174 if Present
(Subt
) then
2175 if Nkind
(Subt
) = N_Subtype_Indication
then
2177 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
2178 Decl
: constant Node_Id
:=
2179 Make_Subtype_Declaration
(Loc
,
2180 Defining_Identifier
=> S
,
2181 Subtype_Indication
=> New_Copy_Tree
(Subt
));
2183 Insert_Before
(Parent
(Parent
(N
)), Decl
);
2185 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
2191 -- Save entity of subtype indication for subsequent check
2193 Bas
:= Entity
(Subt
);
2196 Preanalyze_Range
(Iter_Name
);
2198 -- Set the kind of the loop variable, which is not visible within the
2201 Set_Ekind
(Def_Id
, E_Variable
);
2203 -- Provide a link between the iterator variable and the container, for
2204 -- subsequent use in cross-reference and modification information.
2206 if Of_Present
(N
) then
2207 Set_Related_Expression
(Def_Id
, Iter_Name
);
2209 -- For a container, the iterator is specified through the aspect
2211 if not Is_Array_Type
(Etype
(Iter_Name
)) then
2213 Iterator
: constant Entity_Id
:=
2214 Find_Value_Of_Aspect
2215 (Etype
(Iter_Name
), Aspect_Default_Iterator
);
2221 if No
(Iterator
) then
2222 null; -- error reported below
2224 elsif not Is_Overloaded
(Iterator
) then
2225 Check_Reverse_Iteration
(Etype
(Iterator
));
2227 -- If Iterator is overloaded, use reversible iterator if one is
2230 elsif Is_Overloaded
(Iterator
) then
2231 Get_First_Interp
(Iterator
, I
, It
);
2232 while Present
(It
.Nam
) loop
2233 if Ekind
(It
.Nam
) = E_Function
2234 and then Is_Reversible_Iterator
(Etype
(It
.Nam
))
2236 Set_Etype
(Iterator
, It
.Typ
);
2237 Set_Entity
(Iterator
, It
.Nam
);
2241 Get_Next_Interp
(I
, It
);
2244 Check_Reverse_Iteration
(Etype
(Iterator
));
2250 -- If the domain of iteration is an expression, create a declaration for
2251 -- it, so that finalization actions are introduced outside of the loop.
2252 -- The declaration must be a renaming because the body of the loop may
2253 -- assign to elements.
2255 if not Is_Entity_Name
(Iter_Name
)
2257 -- When the context is a quantified expression, the renaming
2258 -- declaration is delayed until the expansion phase if we are
2261 and then (Nkind
(Parent
(N
)) /= N_Quantified_Expression
2262 or else Operating_Mode
= Check_Semantics
)
2264 -- Do not perform this expansion for ASIS and when expansion is
2265 -- disabled, where the temporary may hide the transformation of a
2266 -- selected component into a prefixed function call, and references
2267 -- need to see the original expression.
2269 and then Expander_Active
2272 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
2278 -- If the domain of iteration is an array component that depends
2279 -- on a discriminant, create actual subtype for it. Pre-analysis
2280 -- does not generate the actual subtype of a selected component.
2282 if Nkind
(Iter_Name
) = N_Selected_Component
2283 and then Is_Array_Type
(Etype
(Iter_Name
))
2286 Build_Actual_Subtype_Of_Component
2287 (Etype
(Selector_Name
(Iter_Name
)), Iter_Name
);
2288 Insert_Action
(N
, Act_S
);
2290 if Present
(Act_S
) then
2291 Typ
:= Defining_Identifier
(Act_S
);
2293 Typ
:= Etype
(Iter_Name
);
2297 Typ
:= Etype
(Iter_Name
);
2299 -- Verify that the expression produces an iterator
2301 if not Of_Present
(N
) and then not Is_Iterator
(Typ
)
2302 and then not Is_Array_Type
(Typ
)
2303 and then No
(Find_Aspect
(Typ
, Aspect_Iterable
))
2306 ("expect object that implements iterator interface",
2311 -- Protect against malformed iterator
2313 if Typ
= Any_Type
then
2314 Error_Msg_N
("invalid expression in loop iterator", Iter_Name
);
2318 if not Of_Present
(N
) then
2319 Check_Reverse_Iteration
(Typ
);
2322 -- The name in the renaming declaration may be a function call.
2323 -- Indicate that it does not come from source, to suppress
2324 -- spurious warnings on renamings of parameterless functions,
2325 -- a common enough idiom in user-defined iterators.
2328 Make_Object_Renaming_Declaration
(Loc
,
2329 Defining_Identifier
=> Id
,
2330 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
2332 New_Copy_Tree
(Iter_Name
, New_Sloc
=> Loc
));
2334 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
2335 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
2336 Set_Etype
(Id
, Typ
);
2337 Set_Etype
(Name
(N
), Typ
);
2340 -- Container is an entity or an array with uncontrolled components, or
2341 -- else it is a container iterator given by a function call, typically
2342 -- called Iterate in the case of predefined containers, even though
2343 -- Iterate is not a reserved name. What matters is that the return type
2344 -- of the function is an iterator type.
2346 elsif Is_Entity_Name
(Iter_Name
) then
2347 Analyze
(Iter_Name
);
2349 if Nkind
(Iter_Name
) = N_Function_Call
then
2351 C
: constant Node_Id
:= Name
(Iter_Name
);
2356 if not Is_Overloaded
(Iter_Name
) then
2357 Resolve
(Iter_Name
, Etype
(C
));
2360 Get_First_Interp
(C
, I
, It
);
2361 while It
.Typ
/= Empty
loop
2362 if Reverse_Present
(N
) then
2363 if Is_Reversible_Iterator
(It
.Typ
) then
2364 Resolve
(Iter_Name
, It
.Typ
);
2368 elsif Is_Iterator
(It
.Typ
) then
2369 Resolve
(Iter_Name
, It
.Typ
);
2373 Get_Next_Interp
(I
, It
);
2378 -- Domain of iteration is not overloaded
2381 Resolve
(Iter_Name
, Etype
(Iter_Name
));
2384 if not Of_Present
(N
) then
2385 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2389 -- Get base type of container, for proper retrieval of Cursor type
2390 -- and primitive operations.
2392 Typ
:= Base_Type
(Etype
(Iter_Name
));
2394 if Is_Array_Type
(Typ
) then
2395 if Of_Present
(N
) then
2396 Set_Etype
(Def_Id
, Component_Type
(Typ
));
2398 -- The loop variable is aliased if the array components are
2401 Set_Is_Aliased
(Def_Id
, Has_Aliased_Components
(Typ
));
2403 -- AI12-0047 stipulates that the domain (array or container)
2404 -- cannot be a component that depends on a discriminant if the
2405 -- enclosing object is mutable, to prevent a modification of the
2406 -- dowmain of iteration in the course of an iteration.
2408 -- If the object is an expression it has been captured in a
2409 -- temporary, so examine original node.
2411 if Nkind
(Original_Node
(Iter_Name
)) = N_Selected_Component
2412 and then Is_Dependent_Component_Of_Mutable_Object
2413 (Original_Node
(Iter_Name
))
2416 ("iterable name cannot be a discriminant-dependent "
2417 & "component of a mutable object", N
);
2420 Check_Subtype_Indication
(Component_Type
(Typ
));
2422 -- Here we have a missing Range attribute
2426 ("missing Range attribute in iteration over an array", N
);
2428 -- In Ada 2012 mode, this may be an attempt at an iterator
2430 if Ada_Version
>= Ada_2012
then
2432 ("\if& is meant to designate an element of the array, use OF",
2436 -- Prevent cascaded errors
2438 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2439 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2442 -- Check for type error in iterator
2444 elsif Typ
= Any_Type
then
2447 -- Iteration over a container
2450 Set_Ekind
(Def_Id
, E_Loop_Parameter
);
2451 Error_Msg_Ada_2012_Feature
("container iterator", Sloc
(N
));
2455 if Of_Present
(N
) then
2456 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2458 Elt
: constant Entity_Id
:=
2459 Get_Iterable_Type_Primitive
(Typ
, Name_Element
);
2463 ("missing Element primitive for iteration", N
);
2465 Set_Etype
(Def_Id
, Etype
(Elt
));
2466 Check_Reverse_Iteration
(Typ
);
2470 Check_Subtype_Indication
(Etype
(Def_Id
));
2472 -- For a predefined container, The type of the loop variable is
2473 -- the Iterator_Element aspect of the container type.
2477 Element
: constant Entity_Id
:=
2478 Find_Value_Of_Aspect
2479 (Typ
, Aspect_Iterator_Element
);
2480 Iterator
: constant Entity_Id
:=
2481 Find_Value_Of_Aspect
2482 (Typ
, Aspect_Default_Iterator
);
2483 Orig_Iter_Name
: constant Node_Id
:=
2484 Original_Node
(Iter_Name
);
2485 Cursor_Type
: Entity_Id
;
2488 if No
(Element
) then
2489 Error_Msg_NE
("cannot iterate over&", N
, Typ
);
2493 Set_Etype
(Def_Id
, Entity
(Element
));
2494 Cursor_Type
:= Get_Cursor_Type
(Typ
);
2495 pragma Assert
(Present
(Cursor_Type
));
2497 Check_Subtype_Indication
(Etype
(Def_Id
));
2499 -- If the container has a variable indexing aspect, the
2500 -- element is a variable and is modifiable in the loop.
2502 if Has_Aspect
(Typ
, Aspect_Variable_Indexing
) then
2503 Set_Ekind
(Def_Id
, E_Variable
);
2506 -- If the container is a constant, iterating over it
2507 -- requires a Constant_Indexing operation.
2509 if not Is_Variable
(Iter_Name
)
2510 and then not Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
2513 ("iteration over constant container require "
2514 & "constant_indexing aspect", N
);
2516 -- The Iterate function may have an in_out parameter,
2517 -- and a constant container is thus illegal.
2519 elsif Present
(Iterator
)
2520 and then Ekind
(Entity
(Iterator
)) = E_Function
2521 and then Ekind
(First_Formal
(Entity
(Iterator
))) /=
2523 and then not Is_Variable
(Iter_Name
)
2525 Error_Msg_N
("variable container expected", N
);
2528 -- Detect a case where the iterator denotes a component
2529 -- of a mutable object which depends on a discriminant.
2530 -- Note that the iterator may denote a function call in
2531 -- qualified form, in which case this check should not
2534 if Nkind
(Orig_Iter_Name
) = N_Selected_Component
2536 Present
(Entity
(Selector_Name
(Orig_Iter_Name
)))
2538 (Entity
(Selector_Name
(Orig_Iter_Name
)),
2541 and then Is_Dependent_Component_Of_Mutable_Object
2545 ("container cannot be a discriminant-dependent "
2546 & "component of a mutable object", N
);
2552 -- IN iterator, domain is a range, or a call to Iterate function
2555 -- For an iteration of the form IN, the name must denote an
2556 -- iterator, typically the result of a call to Iterate. Give a
2557 -- useful error message when the name is a container by itself.
2559 -- The type may be a formal container type, which has to have
2560 -- an Iterable aspect detailing the required primitives.
2562 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2563 and then not Is_Iterator
(Typ
)
2565 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2568 elsif not Has_Aspect
(Typ
, Aspect_Iterator_Element
) then
2570 ("cannot iterate over&", Name
(N
), Typ
);
2573 ("name must be an iterator, not a container", Name
(N
));
2576 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2580 ("\to iterate directly over the elements of a container, "
2581 & "write `of &`", Name
(N
), Original_Node
(Name
(N
)));
2583 -- No point in continuing analysis of iterator spec
2589 -- If the name is a call (typically prefixed) to some Iterate
2590 -- function, it has been rewritten as an object declaration.
2591 -- If that object is a selected component, verify that it is not
2592 -- a component of an unconstrained mutable object.
2594 if Nkind
(Iter_Name
) = N_Identifier
2595 or else (not Expander_Active
and Comes_From_Source
(Iter_Name
))
2598 Orig_Node
: constant Node_Id
:= Original_Node
(Iter_Name
);
2599 Iter_Kind
: constant Node_Kind
:= Nkind
(Orig_Node
);
2603 if Iter_Kind
= N_Selected_Component
then
2604 Obj
:= Prefix
(Orig_Node
);
2606 elsif Iter_Kind
= N_Function_Call
then
2607 Obj
:= First_Actual
(Orig_Node
);
2609 -- If neither, the name comes from source
2615 if Nkind
(Obj
) = N_Selected_Component
2616 and then Is_Dependent_Component_Of_Mutable_Object
(Obj
)
2619 ("container cannot be a discriminant-dependent "
2620 & "component of a mutable object", N
);
2625 -- The result type of Iterate function is the classwide type of
2626 -- the interface parent. We need the specific Cursor type defined
2627 -- in the container package. We obtain it by name for a predefined
2628 -- container, or through the Iterable aspect for a formal one.
2630 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2633 (Parent
(Find_Value_Of_Aspect
(Typ
, Aspect_Iterable
)),
2637 Set_Etype
(Def_Id
, Get_Cursor_Type
(Typ
));
2638 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2643 end Analyze_Iterator_Specification
;
2649 -- Note: the semantic work required for analyzing labels (setting them as
2650 -- reachable) was done in a prepass through the statements in the block,
2651 -- so that forward gotos would be properly handled. See Analyze_Statements
2652 -- for further details. The only processing required here is to deal with
2653 -- optimizations that depend on an assumption of sequential control flow,
2654 -- since of course the occurrence of a label breaks this assumption.
2656 procedure Analyze_Label
(N
: Node_Id
) is
2657 pragma Warnings
(Off
, N
);
2659 Kill_Current_Values
;
2662 --------------------------
2663 -- Analyze_Label_Entity --
2664 --------------------------
2666 procedure Analyze_Label_Entity
(E
: Entity_Id
) is
2668 Set_Ekind
(E
, E_Label
);
2669 Set_Etype
(E
, Standard_Void_Type
);
2670 Set_Enclosing_Scope
(E
, Current_Scope
);
2671 Set_Reachable
(E
, True);
2672 end Analyze_Label_Entity
;
2674 ------------------------------------------
2675 -- Analyze_Loop_Parameter_Specification --
2676 ------------------------------------------
2678 procedure Analyze_Loop_Parameter_Specification
(N
: Node_Id
) is
2679 Loop_Nod
: constant Node_Id
:= Parent
(Parent
(N
));
2681 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
2682 -- If the bounds are given by a 'Range reference on a function call
2683 -- that returns a controlled array, introduce an explicit declaration
2684 -- to capture the bounds, so that the function result can be finalized
2685 -- in timely fashion.
2687 procedure Check_Predicate_Use
(T
: Entity_Id
);
2688 -- Diagnose Attempt to iterate through non-static predicate. Note that
2689 -- a type with inherited predicates may have both static and dynamic
2690 -- forms. In this case it is not sufficent to check the static predicate
2691 -- function only, look for a dynamic predicate aspect as well.
2693 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean;
2694 -- N is the node for an arbitrary construct. This function searches the
2695 -- construct N to see if any expressions within it contain function
2696 -- calls that use the secondary stack, returning True if any such call
2697 -- is found, and False otherwise.
2699 procedure Process_Bounds
(R
: Node_Id
);
2700 -- If the iteration is given by a range, create temporaries and
2701 -- assignment statements block to capture the bounds and perform
2702 -- required finalization actions in case a bound includes a function
2703 -- call that uses the temporary stack. We first pre-analyze a copy of
2704 -- the range in order to determine the expected type, and analyze and
2705 -- resolve the original bounds.
2707 --------------------------------------
2708 -- Check_Controlled_Array_Attribute --
2709 --------------------------------------
2711 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
2713 if Nkind
(DS
) = N_Attribute_Reference
2714 and then Is_Entity_Name
(Prefix
(DS
))
2715 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
2716 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
2718 Is_Controlled
(Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
2719 and then Expander_Active
2722 Loc
: constant Source_Ptr
:= Sloc
(N
);
2723 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
2724 Indx
: constant Entity_Id
:=
2725 Base_Type
(Etype
(First_Index
(Arr
)));
2726 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
2731 Make_Subtype_Declaration
(Loc
,
2732 Defining_Identifier
=> Subt
,
2733 Subtype_Indication
=>
2734 Make_Subtype_Indication
(Loc
,
2735 Subtype_Mark
=> New_Occurrence_Of
(Indx
, Loc
),
2737 Make_Range_Constraint
(Loc
, Relocate_Node
(DS
))));
2738 Insert_Before
(Loop_Nod
, Decl
);
2742 Make_Attribute_Reference
(Loc
,
2743 Prefix
=> New_Occurrence_Of
(Subt
, Loc
),
2744 Attribute_Name
=> Attribute_Name
(DS
)));
2749 end Check_Controlled_Array_Attribute
;
2751 -------------------------
2752 -- Check_Predicate_Use --
2753 -------------------------
2755 procedure Check_Predicate_Use
(T
: Entity_Id
) is
2757 -- A predicated subtype is illegal in loops and related constructs
2758 -- if the predicate is not static, or if it is a non-static subtype
2759 -- of a statically predicated subtype.
2761 if Is_Discrete_Type
(T
)
2762 and then Has_Predicates
(T
)
2763 and then (not Has_Static_Predicate
(T
)
2764 or else not Is_Static_Subtype
(T
)
2765 or else Has_Dynamic_Predicate_Aspect
(T
))
2767 -- Seems a confusing message for the case of a static predicate
2768 -- with a non-static subtype???
2770 Bad_Predicated_Subtype_Use
2771 ("cannot use subtype& with non-static predicate for loop "
2772 & "iteration", Discrete_Subtype_Definition
(N
),
2773 T
, Suggest_Static
=> True);
2775 elsif Inside_A_Generic
2776 and then Is_Generic_Formal
(T
)
2777 and then Is_Discrete_Type
(T
)
2779 Set_No_Dynamic_Predicate_On_Actual
(T
);
2781 end Check_Predicate_Use
;
2783 ------------------------------------
2784 -- Has_Call_Using_Secondary_Stack --
2785 ------------------------------------
2787 function Has_Call_Using_Secondary_Stack
(N
: Node_Id
) return Boolean is
2788 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
2789 -- Check if N is a function call which uses the secondary stack
2795 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
2801 if Nkind
(N
) = N_Function_Call
then
2804 -- Obtain the subprogram being invoked
2807 if Nkind
(Nam
) = N_Explicit_Dereference
then
2808 Nam
:= Prefix
(Nam
);
2810 elsif Nkind
(Nam
) = N_Selected_Component
then
2811 Nam
:= Selector_Name
(Nam
);
2818 Subp
:= Entity
(Nam
);
2819 Typ
:= Etype
(Subp
);
2821 if Requires_Transient_Scope
(Typ
) then
2824 elsif Sec_Stack_Needed_For_Return
(Subp
) then
2829 -- Continue traversing the tree
2834 function Check_Calls
is new Traverse_Func
(Check_Call
);
2836 -- Start of processing for Has_Call_Using_Secondary_Stack
2839 return Check_Calls
(N
) = Abandon
;
2840 end Has_Call_Using_Secondary_Stack
;
2842 --------------------
2843 -- Process_Bounds --
2844 --------------------
2846 procedure Process_Bounds
(R
: Node_Id
) is
2847 Loc
: constant Source_Ptr
:= Sloc
(N
);
2850 (Original_Bound
: Node_Id
;
2851 Analyzed_Bound
: Node_Id
;
2852 Typ
: Entity_Id
) return Node_Id
;
2853 -- Capture value of bound and return captured value
2860 (Original_Bound
: Node_Id
;
2861 Analyzed_Bound
: Node_Id
;
2862 Typ
: Entity_Id
) return Node_Id
2869 -- If the bound is a constant or an object, no need for a separate
2870 -- declaration. If the bound is the result of previous expansion
2871 -- it is already analyzed and should not be modified. Note that
2872 -- the Bound will be resolved later, if needed, as part of the
2873 -- call to Make_Index (literal bounds may need to be resolved to
2876 if Analyzed
(Original_Bound
) then
2877 return Original_Bound
;
2879 elsif Nkind_In
(Analyzed_Bound
, N_Integer_Literal
,
2880 N_Character_Literal
)
2881 or else Is_Entity_Name
(Analyzed_Bound
)
2883 Analyze_And_Resolve
(Original_Bound
, Typ
);
2884 return Original_Bound
;
2887 -- Normally, the best approach is simply to generate a constant
2888 -- declaration that captures the bound. However, there is a nasty
2889 -- case where this is wrong. If the bound is complex, and has a
2890 -- possible use of the secondary stack, we need to generate a
2891 -- separate assignment statement to ensure the creation of a block
2892 -- which will release the secondary stack.
2894 -- We prefer the constant declaration, since it leaves us with a
2895 -- proper trace of the value, useful in optimizations that get rid
2896 -- of junk range checks.
2898 if not Has_Call_Using_Secondary_Stack
(Analyzed_Bound
) then
2899 Analyze_And_Resolve
(Original_Bound
, Typ
);
2901 -- Ensure that the bound is valid. This check should not be
2902 -- generated when the range belongs to a quantified expression
2903 -- as the construct is still not expanded into its final form.
2905 if Nkind
(Parent
(R
)) /= N_Loop_Parameter_Specification
2906 or else Nkind
(Parent
(Parent
(R
))) /= N_Quantified_Expression
2908 Ensure_Valid
(Original_Bound
);
2911 Force_Evaluation
(Original_Bound
);
2912 return Original_Bound
;
2915 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
2917 -- Here we make a declaration with a separate assignment
2918 -- statement, and insert before loop header.
2921 Make_Object_Declaration
(Loc
,
2922 Defining_Identifier
=> Id
,
2923 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
2926 Make_Assignment_Statement
(Loc
,
2927 Name
=> New_Occurrence_Of
(Id
, Loc
),
2928 Expression
=> Relocate_Node
(Original_Bound
));
2930 Insert_Actions
(Loop_Nod
, New_List
(Decl
, Assign
));
2932 -- Now that this temporary variable is initialized we decorate it
2933 -- as safe-to-reevaluate to inform to the backend that no further
2934 -- asignment will be issued and hence it can be handled as side
2935 -- effect free. Note that this decoration must be done when the
2936 -- assignment has been analyzed because otherwise it will be
2937 -- rejected (see Analyze_Assignment).
2939 Set_Is_Safe_To_Reevaluate
(Id
);
2941 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
2943 if Nkind
(Assign
) = N_Assignment_Statement
then
2944 return Expression
(Assign
);
2946 return Original_Bound
;
2950 Hi
: constant Node_Id
:= High_Bound
(R
);
2951 Lo
: constant Node_Id
:= Low_Bound
(R
);
2952 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
2957 -- Start of processing for Process_Bounds
2960 Set_Parent
(R_Copy
, Parent
(R
));
2961 Preanalyze_Range
(R_Copy
);
2962 Typ
:= Etype
(R_Copy
);
2964 -- If the type of the discrete range is Universal_Integer, then the
2965 -- bound's type must be resolved to Integer, and any object used to
2966 -- hold the bound must also have type Integer, unless the literal
2967 -- bounds are constant-folded expressions with a user-defined type.
2969 if Typ
= Universal_Integer
then
2970 if Nkind
(Lo
) = N_Integer_Literal
2971 and then Present
(Etype
(Lo
))
2972 and then Scope
(Etype
(Lo
)) /= Standard_Standard
2976 elsif Nkind
(Hi
) = N_Integer_Literal
2977 and then Present
(Etype
(Hi
))
2978 and then Scope
(Etype
(Hi
)) /= Standard_Standard
2983 Typ
:= Standard_Integer
;
2989 New_Lo
:= One_Bound
(Lo
, Low_Bound
(R_Copy
), Typ
);
2990 New_Hi
:= One_Bound
(Hi
, High_Bound
(R_Copy
), Typ
);
2992 -- Propagate staticness to loop range itself, in case the
2993 -- corresponding subtype is static.
2995 if New_Lo
/= Lo
and then Is_OK_Static_Expression
(New_Lo
) then
2996 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo
));
2999 if New_Hi
/= Hi
and then Is_OK_Static_Expression
(New_Hi
) then
3000 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi
));
3006 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(N
);
3007 Id
: constant Entity_Id
:= Defining_Identifier
(N
);
3011 -- Start of processing for Analyze_Loop_Parameter_Specification
3016 -- We always consider the loop variable to be referenced, since the loop
3017 -- may be used just for counting purposes.
3019 Generate_Reference
(Id
, N
, ' ');
3021 -- Check for the case of loop variable hiding a local variable (used
3022 -- later on to give a nice warning if the hidden variable is never
3026 H
: constant Entity_Id
:= Homonym
(Id
);
3029 and then Ekind
(H
) = E_Variable
3030 and then Is_Discrete_Type
(Etype
(H
))
3031 and then Enclosing_Dynamic_Scope
(H
) = Enclosing_Dynamic_Scope
(Id
)
3033 Set_Hiding_Loop_Variable
(H
, Id
);
3037 -- Loop parameter specification must include subtype mark in SPARK
3039 if Nkind
(DS
) = N_Range
then
3040 Check_SPARK_05_Restriction
3041 ("loop parameter specification must include subtype mark", N
);
3044 -- Analyze the subtype definition and create temporaries for the bounds.
3045 -- Do not evaluate the range when preanalyzing a quantified expression
3046 -- because bounds expressed as function calls with side effects will be
3047 -- incorrectly replicated.
3049 if Nkind
(DS
) = N_Range
3050 and then Expander_Active
3051 and then Nkind
(Parent
(N
)) /= N_Quantified_Expression
3053 Process_Bounds
(DS
);
3055 -- Either the expander not active or the range of iteration is a subtype
3056 -- indication, an entity, or a function call that yields an aggregate or
3060 DS_Copy
:= New_Copy_Tree
(DS
);
3061 Set_Parent
(DS_Copy
, Parent
(DS
));
3062 Preanalyze_Range
(DS_Copy
);
3064 -- Ada 2012: If the domain of iteration is:
3066 -- a) a function call,
3067 -- b) an identifier that is not a type,
3068 -- c) an attribute reference 'Old (within a postcondition),
3069 -- d) an unchecked conversion or a qualified expression with
3070 -- the proper iterator type.
3072 -- then it is an iteration over a container. It was classified as
3073 -- a loop specification by the parser, and must be rewritten now
3074 -- to activate container iteration. The last case will occur within
3075 -- an expanded inlined call, where the expansion wraps an actual in
3076 -- an unchecked conversion when needed. The expression of the
3077 -- conversion is always an object.
3079 if Nkind
(DS_Copy
) = N_Function_Call
3081 or else (Is_Entity_Name
(DS_Copy
)
3082 and then not Is_Type
(Entity
(DS_Copy
)))
3084 or else (Nkind
(DS_Copy
) = N_Attribute_Reference
3085 and then Nam_In
(Attribute_Name
(DS_Copy
),
3086 Name_Loop_Entry
, Name_Old
))
3088 or else Has_Aspect
(Etype
(DS_Copy
), Aspect_Iterable
)
3090 or else Nkind
(DS_Copy
) = N_Unchecked_Type_Conversion
3091 or else (Nkind
(DS_Copy
) = N_Qualified_Expression
3092 and then Is_Iterator
(Etype
(DS_Copy
)))
3094 -- This is an iterator specification. Rewrite it as such and
3095 -- analyze it to capture function calls that may require
3096 -- finalization actions.
3099 I_Spec
: constant Node_Id
:=
3100 Make_Iterator_Specification
(Sloc
(N
),
3101 Defining_Identifier
=> Relocate_Node
(Id
),
3103 Subtype_Indication
=> Empty
,
3104 Reverse_Present
=> Reverse_Present
(N
));
3105 Scheme
: constant Node_Id
:= Parent
(N
);
3108 Set_Iterator_Specification
(Scheme
, I_Spec
);
3109 Set_Loop_Parameter_Specification
(Scheme
, Empty
);
3110 Analyze_Iterator_Specification
(I_Spec
);
3112 -- In a generic context, analyze the original domain of
3113 -- iteration, for name capture.
3115 if not Expander_Active
then
3119 -- Set kind of loop parameter, which may be used in the
3120 -- subsequent analysis of the condition in a quantified
3123 Set_Ekind
(Id
, E_Loop_Parameter
);
3127 -- Domain of iteration is not a function call, and is side-effect
3131 -- A quantified expression that appears in a pre/post condition
3132 -- is pre-analyzed several times. If the range is given by an
3133 -- attribute reference it is rewritten as a range, and this is
3134 -- done even with expansion disabled. If the type is already set
3135 -- do not reanalyze, because a range with static bounds may be
3136 -- typed Integer by default.
3138 if Nkind
(Parent
(N
)) = N_Quantified_Expression
3139 and then Present
(Etype
(DS
))
3152 -- Some additional checks if we are iterating through a type
3154 if Is_Entity_Name
(DS
)
3155 and then Present
(Entity
(DS
))
3156 and then Is_Type
(Entity
(DS
))
3158 -- The subtype indication may denote the completion of an incomplete
3159 -- type declaration.
3161 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
3162 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
3163 Set_Etype
(DS
, Entity
(DS
));
3166 Check_Predicate_Use
(Entity
(DS
));
3169 -- Error if not discrete type
3171 if not Is_Discrete_Type
(Etype
(DS
)) then
3172 Wrong_Type
(DS
, Any_Discrete
);
3173 Set_Etype
(DS
, Any_Type
);
3176 Check_Controlled_Array_Attribute
(DS
);
3178 if Nkind
(DS
) = N_Subtype_Indication
then
3179 Check_Predicate_Use
(Entity
(Subtype_Mark
(DS
)));
3182 Make_Index
(DS
, N
, In_Iter_Schm
=> True);
3183 Set_Ekind
(Id
, E_Loop_Parameter
);
3185 -- A quantified expression which appears in a pre- or post-condition may
3186 -- be analyzed multiple times. The analysis of the range creates several
3187 -- itypes which reside in different scopes depending on whether the pre-
3188 -- or post-condition has been expanded. Update the type of the loop
3189 -- variable to reflect the proper itype at each stage of analysis.
3192 or else Etype
(Id
) = Any_Type
3194 (Present
(Etype
(Id
))
3195 and then Is_Itype
(Etype
(Id
))
3196 and then Nkind
(Parent
(Loop_Nod
)) = N_Expression_With_Actions
3197 and then Nkind
(Original_Node
(Parent
(Loop_Nod
))) =
3198 N_Quantified_Expression
)
3200 Set_Etype
(Id
, Etype
(DS
));
3203 -- Treat a range as an implicit reference to the type, to inhibit
3204 -- spurious warnings.
3206 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
3207 Set_Is_Known_Valid
(Id
, True);
3209 -- The loop is not a declarative part, so the loop variable must be
3210 -- frozen explicitly. Do not freeze while preanalyzing a quantified
3211 -- expression because the freeze node will not be inserted into the
3212 -- tree due to flag Is_Spec_Expression being set.
3214 if Nkind
(Parent
(N
)) /= N_Quantified_Expression
then
3216 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
3218 if Is_Non_Empty_List
(Flist
) then
3219 Insert_Actions
(N
, Flist
);
3224 -- Case where we have a range or a subtype, get type bounds
3226 if Nkind_In
(DS
, N_Range
, N_Subtype_Indication
)
3227 and then not Error_Posted
(DS
)
3228 and then Etype
(DS
) /= Any_Type
3229 and then Is_Discrete_Type
(Etype
(DS
))
3236 if Nkind
(DS
) = N_Range
then
3237 L
:= Low_Bound
(DS
);
3238 H
:= High_Bound
(DS
);
3241 Type_Low_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
3243 Type_High_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
3246 -- Check for null or possibly null range and issue warning. We
3247 -- suppress such messages in generic templates and instances,
3248 -- because in practice they tend to be dubious in these cases. The
3249 -- check applies as well to rewritten array element loops where a
3250 -- null range may be detected statically.
3252 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> True) = GT
then
3254 -- Suppress the warning if inside a generic template or
3255 -- instance, since in practice they tend to be dubious in these
3256 -- cases since they can result from intended parameterization.
3258 if not Inside_A_Generic
and then not In_Instance
then
3260 -- Specialize msg if invalid values could make the loop
3261 -- non-null after all.
3263 if Compile_Time_Compare
3264 (L
, H
, Assume_Valid
=> False) = GT
3266 -- Since we know the range of the loop is null, set the
3267 -- appropriate flag to remove the loop entirely during
3270 Set_Is_Null_Loop
(Loop_Nod
);
3272 if Comes_From_Source
(N
) then
3274 ("??loop range is null, loop will not execute", DS
);
3277 -- Here is where the loop could execute because of
3278 -- invalid values, so issue appropriate message and in
3279 -- this case we do not set the Is_Null_Loop flag since
3280 -- the loop may execute.
3282 elsif Comes_From_Source
(N
) then
3284 ("??loop range may be null, loop may not execute",
3287 ("??can only execute if invalid values are present",
3292 -- In either case, suppress warnings in the body of the loop,
3293 -- since it is likely that these warnings will be inappropriate
3294 -- if the loop never actually executes, which is likely.
3296 Set_Suppress_Loop_Warnings
(Loop_Nod
);
3298 -- The other case for a warning is a reverse loop where the
3299 -- upper bound is the integer literal zero or one, and the
3300 -- lower bound may exceed this value.
3302 -- For example, we have
3304 -- for J in reverse N .. 1 loop
3306 -- In practice, this is very likely to be a case of reversing
3307 -- the bounds incorrectly in the range.
3309 elsif Reverse_Present
(N
)
3310 and then Nkind
(Original_Node
(H
)) = N_Integer_Literal
3312 (Intval
(Original_Node
(H
)) = Uint_0
3314 Intval
(Original_Node
(H
)) = Uint_1
)
3316 -- Lower bound may in fact be known and known not to exceed
3317 -- upper bound (e.g. reverse 0 .. 1) and that's OK.
3319 if Compile_Time_Known_Value
(L
)
3320 and then Expr_Value
(L
) <= Expr_Value
(H
)
3324 -- Otherwise warning is warranted
3327 Error_Msg_N
("??loop range may be null", DS
);
3328 Error_Msg_N
("\??bounds may be wrong way round", DS
);
3332 -- Check if either bound is known to be outside the range of the
3333 -- loop parameter type, this is e.g. the case of a loop from
3334 -- 20..X where the type is 1..19.
3336 -- Such a loop is dubious since either it raises CE or it executes
3337 -- zero times, and that cannot be useful!
3339 if Etype
(DS
) /= Any_Type
3340 and then not Error_Posted
(DS
)
3341 and then Nkind
(DS
) = N_Subtype_Indication
3342 and then Nkind
(Constraint
(DS
)) = N_Range_Constraint
3345 LLo
: constant Node_Id
:=
3346 Low_Bound
(Range_Expression
(Constraint
(DS
)));
3347 LHi
: constant Node_Id
:=
3348 High_Bound
(Range_Expression
(Constraint
(DS
)));
3350 Bad_Bound
: Node_Id
:= Empty
;
3351 -- Suspicious loop bound
3354 -- At this stage L, H are the bounds of the type, and LLo
3355 -- Lhi are the low bound and high bound of the loop.
3357 if Compile_Time_Compare
(LLo
, L
, Assume_Valid
=> True) = LT
3359 Compile_Time_Compare
(LLo
, H
, Assume_Valid
=> True) = GT
3364 if Compile_Time_Compare
(LHi
, L
, Assume_Valid
=> True) = LT
3366 Compile_Time_Compare
(LHi
, H
, Assume_Valid
=> True) = GT
3371 if Present
(Bad_Bound
) then
3373 ("suspicious loop bound out of range of "
3374 & "loop subtype??", Bad_Bound
);
3376 ("\loop executes zero times or raises "
3377 & "Constraint_Error??", Bad_Bound
);
3382 -- This declare block is about warnings, if we get an exception while
3383 -- testing for warnings, we simply abandon the attempt silently. This
3384 -- most likely occurs as the result of a previous error, but might
3385 -- just be an obscure case we have missed. In either case, not giving
3386 -- the warning is perfectly acceptable.
3389 when others => null;
3393 -- A loop parameter cannot be effectively volatile (SPARK RM 7.1.3(4)).
3394 -- This check is relevant only when SPARK_Mode is on as it is not a
3395 -- standard Ada legality check.
3397 if SPARK_Mode
= On
and then Is_Effectively_Volatile
(Id
) then
3398 Error_Msg_N
("loop parameter cannot be volatile", Id
);
3400 end Analyze_Loop_Parameter_Specification
;
3402 ----------------------------
3403 -- Analyze_Loop_Statement --
3404 ----------------------------
3406 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
3408 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean;
3409 -- Given a loop iteration scheme, determine whether it is an Ada 2012
3410 -- container iteration.
3412 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean;
3413 -- Determine whether loop statement N has been wrapped in a block to
3414 -- capture finalization actions that may be generated for container
3415 -- iterators. Prevents infinite recursion when block is analyzed.
3416 -- Routine is a noop if loop is single statement within source block.
3418 ---------------------------
3419 -- Is_Container_Iterator --
3420 ---------------------------
3422 function Is_Container_Iterator
(Iter
: Node_Id
) return Boolean is
3431 elsif Present
(Condition
(Iter
)) then
3434 -- for Def_Id in [reverse] Name loop
3435 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
3437 elsif Present
(Iterator_Specification
(Iter
)) then
3439 Nam
: constant Node_Id
:= Name
(Iterator_Specification
(Iter
));
3443 Nam_Copy
:= New_Copy_Tree
(Nam
);
3444 Set_Parent
(Nam_Copy
, Parent
(Nam
));
3445 Preanalyze_Range
(Nam_Copy
);
3447 -- The only two options here are iteration over a container or
3450 return not Is_Array_Type
(Etype
(Nam_Copy
));
3453 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
3457 LP
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3458 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(LP
);
3462 DS_Copy
:= New_Copy_Tree
(DS
);
3463 Set_Parent
(DS_Copy
, Parent
(DS
));
3464 Preanalyze_Range
(DS_Copy
);
3466 -- Check for a call to Iterate () or an expression with
3467 -- an iterator type.
3470 (Nkind
(DS_Copy
) = N_Function_Call
3471 and then Needs_Finalization
(Etype
(DS_Copy
)))
3472 or else Is_Iterator
(Etype
(DS_Copy
));
3475 end Is_Container_Iterator
;
3477 -------------------------
3478 -- Is_Wrapped_In_Block --
3479 -------------------------
3481 function Is_Wrapped_In_Block
(N
: Node_Id
) return Boolean is
3487 -- Check if current scope is a block that is not a transient block.
3489 if Ekind
(Current_Scope
) /= E_Block
3490 or else No
(Block_Node
(Current_Scope
))
3496 Handled_Statement_Sequence
(Parent
(Block_Node
(Current_Scope
)));
3498 -- Skip leading pragmas that may be introduced for invariant and
3499 -- predicate checks.
3501 Stat
:= First
(Statements
(HSS
));
3502 while Present
(Stat
) and then Nkind
(Stat
) = N_Pragma
loop
3503 Stat
:= Next
(Stat
);
3506 return Stat
= N
and then No
(Next
(Stat
));
3508 end Is_Wrapped_In_Block
;
3510 -- Local declarations
3512 Id
: constant Node_Id
:= Identifier
(N
);
3513 Iter
: constant Node_Id
:= Iteration_Scheme
(N
);
3514 Loc
: constant Source_Ptr
:= Sloc
(N
);
3518 -- Start of processing for Analyze_Loop_Statement
3521 if Present
(Id
) then
3523 -- Make name visible, e.g. for use in exit statements. Loop labels
3524 -- are always considered to be referenced.
3529 -- Guard against serious error (typically, a scope mismatch when
3530 -- semantic analysis is requested) by creating loop entity to
3531 -- continue analysis.
3534 if Total_Errors_Detected
/= 0 then
3535 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3537 raise Program_Error
;
3540 -- Verify that the loop name is hot hidden by an unrelated
3541 -- declaration in an inner scope.
3543 elsif Ekind
(Ent
) /= E_Label
and then Ekind
(Ent
) /= E_Loop
then
3544 Error_Msg_Sloc
:= Sloc
(Ent
);
3545 Error_Msg_N
("implicit label declaration for & is hidden#", Id
);
3547 if Present
(Homonym
(Ent
))
3548 and then Ekind
(Homonym
(Ent
)) = E_Label
3550 Set_Entity
(Id
, Ent
);
3551 Set_Ekind
(Ent
, E_Loop
);
3555 Generate_Reference
(Ent
, N
, ' ');
3556 Generate_Definition
(Ent
);
3558 -- If we found a label, mark its type. If not, ignore it, since it
3559 -- means we have a conflicting declaration, which would already
3560 -- have been diagnosed at declaration time. Set Label_Construct
3561 -- of the implicit label declaration, which is not created by the
3562 -- parser for generic units.
3564 if Ekind
(Ent
) = E_Label
then
3565 Set_Ekind
(Ent
, E_Loop
);
3567 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
3568 Set_Label_Construct
(Parent
(Ent
), N
);
3573 -- Case of no identifier present. Create one and attach it to the
3574 -- loop statement for use as a scope and as a reference for later
3575 -- expansions. Indicate that the label does not come from source,
3576 -- and attach it to the loop statement so it is part of the tree,
3577 -- even without a full declaration.
3580 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3581 Set_Etype
(Ent
, Standard_Void_Type
);
3582 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Loc
));
3583 Set_Parent
(Ent
, N
);
3584 Set_Has_Created_Identifier
(N
);
3587 -- If the iterator specification has a syntactic error, transform
3588 -- construct into an infinite loop to prevent a crash and perform
3592 and then Present
(Iterator_Specification
(Iter
))
3593 and then Error_Posted
(Iterator_Specification
(Iter
))
3595 Set_Iteration_Scheme
(N
, Empty
);
3600 -- Iteration over a container in Ada 2012 involves the creation of a
3601 -- controlled iterator object. Wrap the loop in a block to ensure the
3602 -- timely finalization of the iterator and release of container locks.
3603 -- The same applies to the use of secondary stack when obtaining an
3606 if Ada_Version
>= Ada_2012
3607 and then Is_Container_Iterator
(Iter
)
3608 and then not Is_Wrapped_In_Block
(N
)
3611 Block_Nod
: Node_Id
;
3612 Block_Id
: Entity_Id
;
3616 Make_Block_Statement
(Loc
,
3617 Declarations
=> New_List
,
3618 Handled_Statement_Sequence
=>
3619 Make_Handled_Sequence_Of_Statements
(Loc
,
3620 Statements
=> New_List
(Relocate_Node
(N
))));
3622 Add_Block_Identifier
(Block_Nod
, Block_Id
);
3624 -- The expansion of iterator loops generates an iterator in order
3625 -- to traverse the elements of a container:
3627 -- Iter : <iterator type> := Iterate (Container)'reference;
3629 -- The iterator is controlled and returned on the secondary stack.
3630 -- The analysis of the call to Iterate establishes a transient
3631 -- scope to deal with the secondary stack management, but never
3632 -- really creates a physical block as this would kill the iterator
3633 -- too early (see Wrap_Transient_Declaration). To address this
3634 -- case, mark the generated block as needing secondary stack
3637 Set_Uses_Sec_Stack
(Block_Id
);
3639 Rewrite
(N
, Block_Nod
);
3645 -- Kill current values on entry to loop, since statements in the body of
3646 -- the loop may have been executed before the loop is entered. Similarly
3647 -- we kill values after the loop, since we do not know that the body of
3648 -- the loop was executed.
3650 Kill_Current_Values
;
3652 Analyze_Iteration_Scheme
(Iter
);
3654 -- Check for following case which merits a warning if the type E of is
3655 -- a multi-dimensional array (and no explicit subscript ranges present).
3661 and then Present
(Loop_Parameter_Specification
(Iter
))
3664 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3665 DSD
: constant Node_Id
:=
3666 Original_Node
(Discrete_Subtype_Definition
(LPS
));
3668 if Nkind
(DSD
) = N_Attribute_Reference
3669 and then Attribute_Name
(DSD
) = Name_Range
3670 and then No
(Expressions
(DSD
))
3673 Typ
: constant Entity_Id
:= Etype
(Prefix
(DSD
));
3675 if Is_Array_Type
(Typ
)
3676 and then Number_Dimensions
(Typ
) > 1
3677 and then Nkind
(Parent
(N
)) = N_Loop_Statement
3678 and then Present
(Iteration_Scheme
(Parent
(N
)))
3681 OIter
: constant Node_Id
:=
3682 Iteration_Scheme
(Parent
(N
));
3683 OLPS
: constant Node_Id
:=
3684 Loop_Parameter_Specification
(OIter
);
3685 ODSD
: constant Node_Id
:=
3686 Original_Node
(Discrete_Subtype_Definition
(OLPS
));
3688 if Nkind
(ODSD
) = N_Attribute_Reference
3689 and then Attribute_Name
(ODSD
) = Name_Range
3690 and then No
(Expressions
(ODSD
))
3691 and then Etype
(Prefix
(ODSD
)) = Typ
3693 Error_Msg_Sloc
:= Sloc
(ODSD
);
3695 ("inner range same as outer range#??", DSD
);
3704 -- Analyze the statements of the body except in the case of an Ada 2012
3705 -- iterator with the expander active. In this case the expander will do
3706 -- a rewrite of the loop into a while loop. We will then analyze the
3707 -- loop body when we analyze this while loop.
3709 -- We need to do this delay because if the container is for indefinite
3710 -- types the actual subtype of the components will only be determined
3711 -- when the cursor declaration is analyzed.
3713 -- If the expander is not active then we want to analyze the loop body
3714 -- now even in the Ada 2012 iterator case, since the rewriting will not
3715 -- be done. Insert the loop variable in the current scope, if not done
3716 -- when analysing the iteration scheme. Set its kind properly to detect
3717 -- improper uses in the loop body.
3719 -- In GNATprove mode, we do one of the above depending on the kind of
3720 -- loop. If it is an iterator over an array, then we do not analyze the
3721 -- loop now. We will analyze it after it has been rewritten by the
3722 -- special SPARK expansion which is activated in GNATprove mode. We need
3723 -- to do this so that other expansions that should occur in GNATprove
3724 -- mode take into account the specificities of the rewritten loop, in
3725 -- particular the introduction of a renaming (which needs to be
3728 -- In other cases in GNATprove mode then we want to analyze the loop
3729 -- body now, since no rewriting will occur. Within a generic the
3730 -- GNATprove mode is irrelevant, we must analyze the generic for
3731 -- non-local name capture.
3734 and then Present
(Iterator_Specification
(Iter
))
3737 and then Is_Iterator_Over_Array
(Iterator_Specification
(Iter
))
3738 and then not Inside_A_Generic
3742 elsif not Expander_Active
then
3744 I_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
3745 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
3748 if Scope
(Id
) /= Current_Scope
then
3752 -- In an element iterator, The loop parameter is a variable if
3753 -- the domain of iteration (container or array) is a variable.
3755 if not Of_Present
(I_Spec
)
3756 or else not Is_Variable
(Name
(I_Spec
))
3758 Set_Ekind
(Id
, E_Loop_Parameter
);
3762 Analyze_Statements
(Statements
(N
));
3766 -- Pre-Ada2012 for-loops and while loops
3768 Analyze_Statements
(Statements
(N
));
3771 -- When the iteration scheme of a loop contains attribute 'Loop_Entry,
3772 -- the loop is transformed into a conditional block. Retrieve the loop.
3776 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
3777 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
3780 -- Finish up processing for the loop. We kill all current values, since
3781 -- in general we don't know if the statements in the loop have been
3782 -- executed. We could do a bit better than this with a loop that we
3783 -- know will execute at least once, but it's not worth the trouble and
3784 -- the front end is not in the business of flow tracing.
3786 Process_End_Label
(Stmt
, 'e', Ent
);
3788 Kill_Current_Values
;
3790 -- Check for infinite loop. Skip check for generated code, since it
3791 -- justs waste time and makes debugging the routine called harder.
3793 -- Note that we have to wait till the body of the loop is fully analyzed
3794 -- before making this call, since Check_Infinite_Loop_Warning relies on
3795 -- being able to use semantic visibility information to find references.
3797 if Comes_From_Source
(Stmt
) then
3798 Check_Infinite_Loop_Warning
(Stmt
);
3801 -- Code after loop is unreachable if the loop has no WHILE or FOR and
3802 -- contains no EXIT statements within the body of the loop.
3804 if No
(Iter
) and then not Has_Exit
(Ent
) then
3805 Check_Unreachable_Code
(Stmt
);
3807 end Analyze_Loop_Statement
;
3809 ----------------------------
3810 -- Analyze_Null_Statement --
3811 ----------------------------
3813 -- Note: the semantics of the null statement is implemented by a single
3814 -- null statement, too bad everything isn't as simple as this.
3816 procedure Analyze_Null_Statement
(N
: Node_Id
) is
3817 pragma Warnings
(Off
, N
);
3820 end Analyze_Null_Statement
;
3822 -------------------------
3823 -- Analyze_Target_Name --
3824 -------------------------
3826 procedure Analyze_Target_Name
(N
: Node_Id
) is
3828 -- A target name has the type of the left-hand side of the enclosing
3831 Set_Etype
(N
, Etype
(Name
(Current_Assignment
)));
3832 end Analyze_Target_Name
;
3834 ------------------------
3835 -- Analyze_Statements --
3836 ------------------------
3838 procedure Analyze_Statements
(L
: List_Id
) is
3843 -- The labels declared in the statement list are reachable from
3844 -- statements in the list. We do this as a prepass so that any goto
3845 -- statement will be properly flagged if its target is not reachable.
3846 -- This is not required, but is nice behavior.
3849 while Present
(S
) loop
3850 if Nkind
(S
) = N_Label
then
3851 Analyze
(Identifier
(S
));
3852 Lab
:= Entity
(Identifier
(S
));
3854 -- If we found a label mark it as reachable
3856 if Ekind
(Lab
) = E_Label
then
3857 Generate_Definition
(Lab
);
3858 Set_Reachable
(Lab
);
3860 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
3861 Set_Label_Construct
(Parent
(Lab
), S
);
3864 -- If we failed to find a label, it means the implicit declaration
3865 -- of the label was hidden. A for-loop parameter can do this to
3866 -- a label with the same name inside the loop, since the implicit
3867 -- label declaration is in the innermost enclosing body or block
3871 Error_Msg_Sloc
:= Sloc
(Lab
);
3873 ("implicit label declaration for & is hidden#",
3881 -- Perform semantic analysis on all statements
3883 Conditional_Statements_Begin
;
3886 while Present
(S
) loop
3889 -- Remove dimension in all statements
3891 Remove_Dimension_In_Statement
(S
);
3895 Conditional_Statements_End
;
3897 -- Make labels unreachable. Visibility is not sufficient, because labels
3898 -- in one if-branch for example are not reachable from the other branch,
3899 -- even though their declarations are in the enclosing declarative part.
3902 while Present
(S
) loop
3903 if Nkind
(S
) = N_Label
then
3904 Set_Reachable
(Entity
(Identifier
(S
)), False);
3909 end Analyze_Statements
;
3911 ----------------------------
3912 -- Check_Unreachable_Code --
3913 ----------------------------
3915 procedure Check_Unreachable_Code
(N
: Node_Id
) is
3916 Error_Node
: Node_Id
;
3920 if Is_List_Member
(N
) and then Comes_From_Source
(N
) then
3925 Nxt
:= Original_Node
(Next
(N
));
3927 -- Skip past pragmas
3929 while Nkind
(Nxt
) = N_Pragma
loop
3930 Nxt
:= Original_Node
(Next
(Nxt
));
3933 -- If a label follows us, then we never have dead code, since
3934 -- someone could branch to the label, so we just ignore it, unless
3935 -- we are in formal mode where goto statements are not allowed.
3937 if Nkind
(Nxt
) = N_Label
3938 and then not Restriction_Check_Required
(SPARK_05
)
3942 -- Otherwise see if we have a real statement following us
3945 and then Comes_From_Source
(Nxt
)
3946 and then Is_Statement
(Nxt
)
3948 -- Special very annoying exception. If we have a return that
3949 -- follows a raise, then we allow it without a warning, since
3950 -- the Ada RM annoyingly requires a useless return here.
3952 if Nkind
(Original_Node
(N
)) /= N_Raise_Statement
3953 or else Nkind
(Nxt
) /= N_Simple_Return_Statement
3955 -- The rather strange shenanigans with the warning message
3956 -- here reflects the fact that Kill_Dead_Code is very good
3957 -- at removing warnings in deleted code, and this is one
3958 -- warning we would prefer NOT to have removed.
3962 -- If we have unreachable code, analyze and remove the
3963 -- unreachable code, since it is useless and we don't
3964 -- want to generate junk warnings.
3966 -- We skip this step if we are not in code generation mode
3967 -- or CodePeer mode.
3969 -- This is the one case where we remove dead code in the
3970 -- semantics as opposed to the expander, and we do not want
3971 -- to remove code if we are not in code generation mode,
3972 -- since this messes up the ASIS trees or loses useful
3973 -- information in the CodePeer tree.
3975 -- Note that one might react by moving the whole circuit to
3976 -- exp_ch5, but then we lose the warning in -gnatc mode.
3978 if Operating_Mode
= Generate_Code
3979 and then not CodePeer_Mode
3984 -- Quit deleting when we have nothing more to delete
3985 -- or if we hit a label (since someone could transfer
3986 -- control to a label, so we should not delete it).
3988 exit when No
(Nxt
) or else Nkind
(Nxt
) = N_Label
;
3990 -- Statement/declaration is to be deleted
3994 Kill_Dead_Code
(Nxt
);
3998 -- Now issue the warning (or error in formal mode)
4000 if Restriction_Check_Required
(SPARK_05
) then
4001 Check_SPARK_05_Restriction
4002 ("unreachable code is not allowed", Error_Node
);
4005 ("??unreachable code!", Sloc
(Error_Node
), Error_Node
);
4009 -- If the unconditional transfer of control instruction is the
4010 -- last statement of a sequence, then see if our parent is one of
4011 -- the constructs for which we count unblocked exits, and if so,
4012 -- adjust the count.
4017 -- Statements in THEN part or ELSE part of IF statement
4019 if Nkind
(P
) = N_If_Statement
then
4022 -- Statements in ELSIF part of an IF statement
4024 elsif Nkind
(P
) = N_Elsif_Part
then
4026 pragma Assert
(Nkind
(P
) = N_If_Statement
);
4028 -- Statements in CASE statement alternative
4030 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
4032 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
4034 -- Statements in body of block
4036 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
4037 and then Nkind
(Parent
(P
)) = N_Block_Statement
4039 -- The original loop is now placed inside a block statement
4040 -- due to the expansion of attribute 'Loop_Entry. Return as
4041 -- this is not a "real" block for the purposes of exit
4044 if Nkind
(N
) = N_Loop_Statement
4045 and then Subject_To_Loop_Entry_Attributes
(N
)
4050 -- Statements in exception handler in a block
4052 elsif Nkind
(P
) = N_Exception_Handler
4053 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
4054 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
4058 -- None of these cases, so return
4064 -- This was one of the cases we are looking for (i.e. the
4065 -- parent construct was IF, CASE or block) so decrement count.
4067 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
4071 end Check_Unreachable_Code
;
4073 ----------------------
4074 -- Preanalyze_Range --
4075 ----------------------
4077 procedure Preanalyze_Range
(R_Copy
: Node_Id
) is
4078 Save_Analysis
: constant Boolean := Full_Analysis
;
4082 Full_Analysis
:= False;
4083 Expander_Mode_Save_And_Set
(False);
4085 -- In addition to the above we must ecplicity suppress the
4086 -- generation of freeze nodes which might otherwise be generated
4087 -- during resolution of the range (e.g. if given by an attribute
4088 -- that will freeze its prefix).
4090 Set_Must_Not_Freeze
(R_Copy
);
4092 if Nkind
(R_Copy
) = N_Attribute_Reference
then
4093 Set_Must_Not_Freeze
(Prefix
(R_Copy
));
4098 if Nkind
(R_Copy
) in N_Subexpr
and then Is_Overloaded
(R_Copy
) then
4100 -- Apply preference rules for range of predefined integer types, or
4101 -- check for array or iterable construct for "of" iterator, or
4102 -- diagnose true ambiguity.
4107 Found
: Entity_Id
:= Empty
;
4110 Get_First_Interp
(R_Copy
, I
, It
);
4111 while Present
(It
.Typ
) loop
4112 if Is_Discrete_Type
(It
.Typ
) then
4116 if Scope
(Found
) = Standard_Standard
then
4119 elsif Scope
(It
.Typ
) = Standard_Standard
then
4123 -- Both of them are user-defined
4126 ("ambiguous bounds in range of iteration", R_Copy
);
4127 Error_Msg_N
("\possible interpretations:", R_Copy
);
4128 Error_Msg_NE
("\\} ", R_Copy
, Found
);
4129 Error_Msg_NE
("\\} ", R_Copy
, It
.Typ
);
4134 elsif Nkind
(Parent
(R_Copy
)) = N_Iterator_Specification
4135 and then Of_Present
(Parent
(R_Copy
))
4137 if Is_Array_Type
(It
.Typ
)
4138 or else Has_Aspect
(It
.Typ
, Aspect_Iterator_Element
)
4139 or else Has_Aspect
(It
.Typ
, Aspect_Constant_Indexing
)
4140 or else Has_Aspect
(It
.Typ
, Aspect_Variable_Indexing
)
4144 Set_Etype
(R_Copy
, It
.Typ
);
4147 Error_Msg_N
("ambiguous domain of iteration", R_Copy
);
4152 Get_Next_Interp
(I
, It
);
4157 -- Subtype mark in iteration scheme
4159 if Is_Entity_Name
(R_Copy
) and then Is_Type
(Entity
(R_Copy
)) then
4162 -- Expression in range, or Ada 2012 iterator
4164 elsif Nkind
(R_Copy
) in N_Subexpr
then
4166 Typ
:= Etype
(R_Copy
);
4168 if Is_Discrete_Type
(Typ
) then
4171 -- Check that the resulting object is an iterable container
4173 elsif Has_Aspect
(Typ
, Aspect_Iterator_Element
)
4174 or else Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
4175 or else Has_Aspect
(Typ
, Aspect_Variable_Indexing
)
4179 -- The expression may yield an implicit reference to an iterable
4180 -- container. Insert explicit dereference so that proper type is
4181 -- visible in the loop.
4183 elsif Has_Implicit_Dereference
(Etype
(R_Copy
)) then
4188 Disc
:= First_Discriminant
(Typ
);
4189 while Present
(Disc
) loop
4190 if Has_Implicit_Dereference
(Disc
) then
4191 Build_Explicit_Dereference
(R_Copy
, Disc
);
4195 Next_Discriminant
(Disc
);
4202 Expander_Mode_Restore
;
4203 Full_Analysis
:= Save_Analysis
;
4204 end Preanalyze_Range
;