1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2024, 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 Debug
; use Debug
;
30 with Einfo
; use Einfo
;
31 with Einfo
.Entities
; use Einfo
.Entities
;
32 with Einfo
.Utils
; use Einfo
.Utils
;
33 with Errout
; use Errout
;
34 with Expander
; use Expander
;
35 with Exp_Ch6
; use Exp_Ch6
;
36 with Exp_Tss
; use Exp_Tss
;
37 with Exp_Util
; use Exp_Util
;
38 with Freeze
; use Freeze
;
39 with Ghost
; use Ghost
;
41 with Lib
.Xref
; use Lib
.Xref
;
42 with Namet
; use Namet
;
43 with Nlists
; use Nlists
;
44 with Nmake
; use Nmake
;
47 with Sem_Aux
; use Sem_Aux
;
48 with Sem_Case
; use Sem_Case
;
49 with Sem_Ch3
; use Sem_Ch3
;
50 with Sem_Ch6
; use Sem_Ch6
;
51 with Sem_Ch8
; use Sem_Ch8
;
52 with Sem_Dim
; use Sem_Dim
;
53 with Sem_Disp
; use Sem_Disp
;
54 with Sem_Elab
; use Sem_Elab
;
55 with Sem_Eval
; use Sem_Eval
;
56 with Sem_Res
; use Sem_Res
;
57 with Sem_Type
; use Sem_Type
;
58 with Sem_Util
; use Sem_Util
;
59 with Sem_Warn
; use Sem_Warn
;
60 with Snames
; use Snames
;
61 with Stand
; use Stand
;
62 with Sinfo
; use Sinfo
;
63 with Sinfo
.Nodes
; use Sinfo
.Nodes
;
64 with Sinfo
.Utils
; use Sinfo
.Utils
;
65 with Targparm
; use Targparm
;
66 with Tbuild
; use Tbuild
;
67 with Ttypes
; use Ttypes
;
68 with Uintp
; use Uintp
;
69 with Warnsw
; use Warnsw
;
71 package body Sem_Ch5
is
73 Current_Assignment
: Node_Id
:= Empty
;
74 -- This variable holds the node for an assignment that contains target
75 -- names. The corresponding flag has been set by the parser, and when
76 -- set the analysis of the RHS must be done with all expansion disabled,
77 -- because the assignment is reanalyzed after expansion has replaced all
78 -- occurrences of the target name appropriately.
80 Unblocked_Exit_Count
: Nat
:= 0;
81 -- This variable is used when processing if statements, case statements,
82 -- and block statements. It counts the number of exit points that are not
83 -- blocked by unconditional transfer instructions: for IF and CASE, these
84 -- are the branches of the conditional; for a block, they are the statement
85 -- sequence of the block, and the statement sequences of any exception
86 -- handlers that are part of the block. When processing is complete, if
87 -- this count is zero, it means that control cannot fall through the IF,
88 -- CASE or block statement. This is used for the generation of warning
89 -- messages. This variable is recursively saved on entry to processing the
90 -- construct, and restored on exit.
92 function Has_Sec_Stack_Call
(N
: Node_Id
) return Boolean;
93 -- N is the node for an arbitrary construct. This function searches the
94 -- construct N to see if it contains a function call that returns on the
95 -- secondary stack, returning True if any such call is found, and False
98 -- ??? The implementation invokes Sem_Util.Requires_Transient_Scope so it
99 -- will return True if N contains a function call that needs finalization,
100 -- in addition to the above specification. See Analyze_Loop_Statement for
101 -- a similar comment about this entanglement.
103 procedure Preanalyze_Range
(R_Copy
: Node_Id
);
104 -- Determine expected type of range or domain of iteration of Ada 2012
105 -- loop by analyzing separate copy. Do the analysis and resolution of the
106 -- copy of the bound(s) with expansion disabled, to prevent the generation
107 -- of finalization actions. This prevents memory leaks when the bounds
108 -- contain calls to functions returning controlled arrays or when the
109 -- domain of iteration is a container.
111 ------------------------
112 -- Analyze_Assignment --
113 ------------------------
115 -- WARNING: This routine manages Ghost regions. Return statements must be
116 -- replaced by gotos which jump to the end of the routine and restore the
119 procedure Analyze_Assignment
(N
: Node_Id
) is
120 Lhs
: constant Node_Id
:= Name
(N
);
121 Rhs
: constant Node_Id
:= Expression
(N
);
123 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
);
124 -- N is the node for the left hand side of an assignment, and it is not
125 -- a variable. This routine issues an appropriate diagnostic.
127 function Is_Protected_Part_Of_Constituent
128 (Nod
: Node_Id
) return Boolean;
129 -- Determine whether arbitrary node Nod denotes a Part_Of constituent of
130 -- a single protected type.
133 -- This is called to kill current value settings of a simple variable
134 -- on the left hand side. We call it if we find any error in analyzing
135 -- the assignment, and at the end of processing before setting any new
136 -- current values in place.
138 procedure Set_Assignment_Type
140 Opnd_Type
: in out Entity_Id
);
141 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
142 -- nominal subtype. This procedure is used to deal with cases where the
143 -- nominal subtype must be replaced by the actual subtype.
145 function Within_Function
return Boolean;
146 -- Determine whether the current scope is a function or appears within
149 -------------------------------
150 -- Diagnose_Non_Variable_Lhs --
151 -------------------------------
153 procedure Diagnose_Non_Variable_Lhs
(N
: Node_Id
) is
155 -- Not worth posting another error if left hand side already flagged
156 -- as being illegal in some respect.
158 if Error_Posted
(N
) then
161 -- Some special bad cases of entity names
163 elsif Is_Entity_Name
(N
) then
165 Ent
: constant Entity_Id
:= Entity
(N
);
168 if Ekind
(Ent
) = E_Loop_Parameter
169 or else Is_Loop_Parameter
(Ent
)
171 Error_Msg_N
("assignment to loop parameter not allowed", N
);
174 elsif Ekind
(Ent
) = E_In_Parameter
then
176 ("assignment to IN mode parameter not allowed", N
);
179 -- Renamings of protected private components are turned into
180 -- constants when compiling a protected function. In the case
181 -- of single protected types, the private component appears
184 elsif (Is_Prival
(Ent
) and then Within_Function
)
185 or else Is_Protected_Component
(Ent
)
188 ("protected function cannot modify its protected object",
194 -- For indexed components, test prefix if it is in array. We do not
195 -- want to recurse for cases where the prefix is a pointer, since we
196 -- may get a message confusing the pointer and what it references.
198 elsif Nkind
(N
) = N_Indexed_Component
199 and then Is_Array_Type
(Etype
(Prefix
(N
)))
201 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
204 -- Another special case for assignment to discriminant
206 elsif Nkind
(N
) = N_Selected_Component
then
207 if Present
(Entity
(Selector_Name
(N
)))
208 and then Ekind
(Entity
(Selector_Name
(N
))) = E_Discriminant
210 Error_Msg_N
("assignment to discriminant not allowed", N
);
213 -- For selection from record, diagnose prefix, but note that again
214 -- we only do this for a record, not e.g. for a pointer.
216 elsif Is_Record_Type
(Etype
(Prefix
(N
))) then
217 Diagnose_Non_Variable_Lhs
(Prefix
(N
));
222 -- If we fall through, we have no special message to issue
224 Error_Msg_N
("left hand side of assignment must be a variable", N
);
225 end Diagnose_Non_Variable_Lhs
;
227 --------------------------------------
228 -- Is_Protected_Part_Of_Constituent --
229 --------------------------------------
231 function Is_Protected_Part_Of_Constituent
232 (Nod
: Node_Id
) return Boolean
234 Encap_Id
: Entity_Id
;
238 -- Abstract states and variables may act as Part_Of constituents of
239 -- single protected types, however only variables can be modified by
242 if Is_Entity_Name
(Nod
) then
243 Var_Id
:= Entity
(Nod
);
245 if Present
(Var_Id
) and then Ekind
(Var_Id
) = E_Variable
then
246 Encap_Id
:= Encapsulating_State
(Var_Id
);
248 -- To qualify, the node must denote a reference to a variable
249 -- whose encapsulating state is a single protected object.
253 and then Is_Single_Protected_Object
(Encap_Id
);
258 end Is_Protected_Part_Of_Constituent
;
264 procedure Kill_Lhs
is
266 if Is_Entity_Name
(Lhs
) then
268 Ent
: constant Entity_Id
:= Entity
(Lhs
);
270 if Present
(Ent
) then
271 Kill_Current_Values
(Ent
);
277 -------------------------
278 -- Set_Assignment_Type --
279 -------------------------
281 procedure Set_Assignment_Type
283 Opnd_Type
: in out Entity_Id
)
288 Require_Entity
(Opnd
);
290 -- If the assignment operand is an in-out or out parameter, then we
291 -- get the actual subtype (needed for the unconstrained case). If the
292 -- operand is the actual in an entry declaration, then within the
293 -- accept statement it is replaced with a local renaming, which may
294 -- also have an actual subtype. Likewise for a return object that
295 -- lives on the secondary stack.
297 if Is_Entity_Name
(Opnd
)
298 and then (Ekind
(Entity
(Opnd
)) in E_Out_Parameter
300 | E_Generic_In_Out_Parameter
302 (Ekind
(Entity
(Opnd
)) = E_Variable
303 and then Nkind
(Parent
(Entity
(Opnd
))) =
304 N_Object_Renaming_Declaration
305 and then Nkind
(Parent
(Parent
(Entity
(Opnd
)))) =
307 or else Is_Secondary_Stack_Return_Object
(Entity
(Opnd
)))
309 Opnd_Type
:= Get_Actual_Subtype
(Opnd
);
311 -- If the assignment operand is a component reference, then we build
312 -- the actual subtype of the component for the unconstrained case,
313 -- unless there is already one or the type is an unchecked union.
315 elsif (Nkind
(Opnd
) = N_Selected_Component
316 or else (Nkind
(Opnd
) = N_Explicit_Dereference
317 and then No
(Actual_Designated_Subtype
(Opnd
))))
318 and then not Is_Unchecked_Union
(Opnd_Type
)
320 Decl
:= Build_Actual_Subtype_Of_Component
(Opnd_Type
, Opnd
);
322 if Present
(Decl
) then
323 Insert_Action
(N
, Decl
);
324 Mark_Rewrite_Insertion
(Decl
);
326 Opnd_Type
:= Defining_Identifier
(Decl
);
327 Set_Etype
(Opnd
, Opnd_Type
);
328 Freeze_Itype
(Opnd_Type
, N
);
330 elsif Is_Constrained
(Etype
(Opnd
)) then
331 Opnd_Type
:= Etype
(Opnd
);
334 -- For slice, use the constrained subtype created for the slice
336 elsif Nkind
(Opnd
) = N_Slice
then
337 Opnd_Type
:= Etype
(Opnd
);
339 end Set_Assignment_Type
;
341 ---------------------
342 -- Within_Function --
343 ---------------------
345 function Within_Function
return Boolean is
346 Scop_Id
: constant Entity_Id
:= Current_Scope
;
349 if Ekind
(Scop_Id
) = E_Function
then
352 elsif Ekind
(Enclosing_Dynamic_Scope
(Scop_Id
)) = E_Function
then
361 Saved_GM
: constant Ghost_Mode_Type
:= Ghost_Mode
;
362 Saved_IGR
: constant Node_Id
:= Ignored_Ghost_Region
;
363 -- Save the Ghost-related attributes to restore on exit
368 Save_Full_Analysis
: Boolean := False;
369 -- Force initialization to facilitate static analysis
371 -- Start of processing for Analyze_Assignment
374 Mark_Coextensions
(N
, Rhs
);
376 -- Preserve relevant elaboration-related attributes of the context which
377 -- are no longer available or very expensive to recompute once analysis,
378 -- resolution, and expansion are over.
380 Mark_Elaboration_Attributes
385 -- An assignment statement is Ghost when the left hand side denotes a
386 -- Ghost entity. Set the mode now to ensure that any nodes generated
387 -- during analysis and expansion are properly marked as Ghost.
389 Mark_And_Set_Ghost_Assignment
(N
);
391 if Has_Target_Names
(N
) then
392 pragma Assert
(No
(Current_Assignment
));
393 Current_Assignment
:= N
;
394 Expander_Mode_Save_And_Set
(False);
395 Save_Full_Analysis
:= Full_Analysis
;
396 Full_Analysis
:= False;
402 -- Ensure that we never do an assignment on a variable marked as
403 -- Is_Safe_To_Reevaluate.
406 (not Is_Entity_Name
(Lhs
)
407 or else Ekind
(Entity
(Lhs
)) /= E_Variable
408 or else not Is_Safe_To_Reevaluate
(Entity
(Lhs
)));
410 -- Start type analysis for assignment
414 -- In the most general case, both Lhs and Rhs can be overloaded, and we
415 -- must compute the intersection of the possible types on each side.
417 if Is_Overloaded
(Lhs
) then
424 Get_First_Interp
(Lhs
, I
, It
);
426 while Present
(It
.Typ
) loop
428 -- An indexed component with generalized indexing is always
429 -- overloaded with the corresponding dereference. Discard the
430 -- interpretation that yields a reference type, which is not
433 if Nkind
(Lhs
) = N_Indexed_Component
434 and then Present
(Generalized_Indexing
(Lhs
))
435 and then Has_Implicit_Dereference
(It
.Typ
)
439 -- This may be a call to a parameterless function through an
440 -- implicit dereference, so discard interpretation as well.
442 elsif Is_Entity_Name
(Lhs
)
443 and then Has_Implicit_Dereference
(It
.Typ
)
447 elsif Has_Compatible_Type
(Rhs
, It
.Typ
) then
448 if T1
= Any_Type
then
451 -- An explicit dereference is overloaded if the prefix
452 -- is. Try to remove the ambiguity on the prefix, the
453 -- error will be posted there if the ambiguity is real.
455 if Nkind
(Lhs
) = N_Explicit_Dereference
then
458 PI1
: Interp_Index
:= 0;
464 Get_First_Interp
(Prefix
(Lhs
), PI
, PIt
);
466 while Present
(PIt
.Typ
) loop
467 if Is_Access_Type
(PIt
.Typ
)
468 and then Has_Compatible_Type
469 (Rhs
, Designated_Type
(PIt
.Typ
))
473 Disambiguate
(Prefix
(Lhs
),
476 if PIt
= No_Interp
then
478 ("ambiguous left-hand side in "
479 & "assignment", Lhs
);
482 Resolve
(Prefix
(Lhs
), PIt
.Typ
);
492 Get_Next_Interp
(PI
, PIt
);
498 ("ambiguous left-hand side in assignment", Lhs
);
504 Get_Next_Interp
(I
, It
);
508 if T1
= Any_Type
then
510 ("no valid types for left-hand side for assignment", Lhs
);
516 -- The resulting assignment type is T1, so now we will resolve the left
517 -- hand side of the assignment using this determined type.
521 -- Cases where Lhs is not a variable. In an instance or an inlined body
522 -- no need for further check because assignment was legal in template.
524 if In_Inlined_Body
then
527 elsif not Is_Variable
(Lhs
) then
529 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
537 if Ada_Version
>= Ada_2005
then
539 -- Handle chains of renamings
542 while Nkind
(Ent
) in N_Has_Entity
543 and then Present
(Entity
(Ent
))
544 and then Is_Object
(Entity
(Ent
))
545 and then Present
(Renamed_Object
(Entity
(Ent
)))
547 Ent
:= Renamed_Object
(Entity
(Ent
));
550 if (Nkind
(Ent
) = N_Attribute_Reference
551 and then Attribute_Name
(Ent
) = Name_Priority
)
553 -- Renamings of the attribute Priority applied to protected
554 -- objects have been previously expanded into calls to the
555 -- Get_Ceiling run-time subprogram.
557 or else Is_Expanded_Priority_Attribute
(Ent
)
559 -- The enclosing subprogram cannot be a protected function
562 while not (Is_Subprogram
(S
)
563 and then Convention
(S
) = Convention_Protected
)
564 and then S
/= Standard_Standard
569 if Ekind
(S
) = E_Function
570 and then Convention
(S
) = Convention_Protected
573 ("protected function cannot modify its protected " &
578 -- Changes of the ceiling priority of the protected object
579 -- are only effective if the Ceiling_Locking policy is in
580 -- effect (AARM D.5.2 (5/2)).
582 if Locking_Policy
/= 'C' then
584 ("assignment to the attribute PRIORITY has no effect??",
587 ("\since no Locking_Policy has been specified??", Lhs
);
595 Diagnose_Non_Variable_Lhs
(Lhs
);
598 -- Error of assigning to limited type. We do however allow this in
599 -- certain cases where the front end generates the assignments.
601 elsif Is_Limited_Type
(T1
)
602 and then not Assignment_OK
(Lhs
)
603 and then not Assignment_OK
(Original_Node
(Lhs
))
605 -- CPP constructors can only be called in declarations
607 if Is_CPP_Constructor_Call
(Rhs
) then
608 Error_Msg_N
("invalid use of 'C'P'P constructor", Rhs
);
611 ("left hand of assignment must not be limited type", Lhs
);
612 Explain_Limited_Type
(T1
, Lhs
);
617 -- A class-wide type may be a limited view. This illegal case is not
618 -- caught by previous checks.
620 elsif Ekind
(T1
) = E_Class_Wide_Type
and then From_Limited_With
(T1
) then
621 Error_Msg_NE
("invalid use of limited view of&", Lhs
, T1
);
624 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
625 -- abstract. This is only checked when the assignment Comes_From_Source,
626 -- because in some cases the expander generates such assignments (such
627 -- in the _assign operation for an abstract type).
629 elsif Is_Abstract_Type
(T1
) and then Comes_From_Source
(N
) then
631 ("target of assignment operation must not be abstract", Lhs
);
634 -- Variables which are Part_Of constituents of single protected types
635 -- behave in similar fashion to protected components. Such variables
636 -- cannot be modified by protected functions.
638 if Is_Protected_Part_Of_Constituent
(Lhs
) and then Within_Function
then
640 ("protected function cannot modify its protected object", Lhs
);
643 -- Resolution may have updated the subtype, in case the left-hand side
644 -- is a private protected component. Use the correct subtype to avoid
645 -- scoping issues in the back-end.
649 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
650 -- type. For example:
654 -- type Acc is access P.T;
657 -- with Pkg; use Acc;
658 -- procedure Example is
661 -- A.all := B.all; -- ERROR
664 if Nkind
(Lhs
) = N_Explicit_Dereference
665 and then Ekind
(T1
) = E_Incomplete_Type
667 Error_Msg_N
("invalid use of incomplete type", Lhs
);
672 -- Now we can complete the resolution of the right hand side
674 Set_Assignment_Type
(Lhs
, T1
);
676 -- If the target of the assignment is an entity of a mutable type and
677 -- the expression is a conditional expression, its alternatives can be
678 -- of different subtypes of the nominal type of the LHS, so they must be
679 -- resolved with the base type, given that their subtype may differ from
680 -- that of the target mutable object.
682 if Is_Entity_Name
(Lhs
)
683 and then Is_Assignable
(Entity
(Lhs
))
684 and then Is_Composite_Type
(T1
)
685 and then not Is_Constrained
(Etype
(Entity
(Lhs
)))
686 and then Nkind
(Rhs
) in N_If_Expression | N_Case_Expression
688 Resolve
(Rhs
, Base_Type
(T1
));
694 -- This is the point at which we check for an unset reference
696 Check_Unset_Reference
(Rhs
);
697 Check_Unprotected_Access
(Lhs
, Rhs
);
699 -- Remaining steps are skipped if Rhs was syntactically in error
708 if not Covers
(T1
, T2
) then
709 Wrong_Type
(Rhs
, Etype
(Lhs
));
714 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
715 -- types, use the non-limited view if available
717 if Nkind
(Rhs
) = N_Explicit_Dereference
718 and then Is_Tagged_Type
(T2
)
719 and then Has_Non_Limited_View
(T2
)
721 T2
:= Non_Limited_View
(T2
);
724 Set_Assignment_Type
(Rhs
, T2
);
726 if Total_Errors_Detected
/= 0 then
736 if T1
= Any_Type
or else T2
= Any_Type
then
741 -- If the rhs is class-wide or dynamically tagged, then require the lhs
742 -- to be class-wide. The case where the rhs is a dynamically tagged call
743 -- to a dispatching operation with a controlling access result is
744 -- excluded from this check, since the target has an access type (and
745 -- no tag propagation occurs in that case).
747 if (Is_Class_Wide_Type
(T2
)
748 or else (Is_Dynamically_Tagged
(Rhs
)
749 and then not Is_Access_Type
(T1
)))
750 and then not Is_Class_Wide_Type
(T1
)
752 Error_Msg_N
("dynamically tagged expression not allowed!", Rhs
);
754 elsif Is_Class_Wide_Type
(T1
)
755 and then not Is_Class_Wide_Type
(T2
)
756 and then not Is_Tag_Indeterminate
(Rhs
)
757 and then not Is_Dynamically_Tagged
(Rhs
)
759 Error_Msg_N
("dynamically tagged expression required!", Rhs
);
762 -- Propagate the tag from a class-wide target to the rhs when the rhs
763 -- is a tag-indeterminate call.
765 if Is_Tag_Indeterminate
(Rhs
) then
766 if Is_Class_Wide_Type
(T1
) then
767 Propagate_Tag
(Lhs
, Rhs
);
769 elsif Nkind
(Rhs
) = N_Function_Call
770 and then Is_Entity_Name
(Name
(Rhs
))
771 and then Is_Abstract_Subprogram
(Entity
(Name
(Rhs
)))
774 ("call to abstract function must be dispatching", Name
(Rhs
));
776 elsif Nkind
(Rhs
) = N_Qualified_Expression
777 and then Nkind
(Expression
(Rhs
)) = N_Function_Call
778 and then Is_Entity_Name
(Name
(Expression
(Rhs
)))
780 Is_Abstract_Subprogram
(Entity
(Name
(Expression
(Rhs
))))
783 ("call to abstract function must be dispatching",
784 Name
(Expression
(Rhs
)));
788 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
789 -- apply an implicit conversion of the rhs to that type to force
790 -- appropriate static and run-time accessibility checks. This applies
791 -- as well to anonymous access-to-subprogram types that are component
792 -- subtypes or formal parameters.
794 if Ada_Version
>= Ada_2005
and then Is_Access_Type
(T1
) then
795 if Is_Local_Anonymous_Access
(T1
)
796 or else Ekind
(T2
) = E_Anonymous_Access_Subprogram_Type
798 -- Handle assignment to an Ada 2012 stand-alone object
799 -- of an anonymous access type.
801 or else (Ekind
(T1
) = E_Anonymous_Access_Type
802 and then Nkind
(Associated_Node_For_Itype
(T1
)) =
803 N_Object_Declaration
)
806 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
807 Analyze_And_Resolve
(Rhs
, T1
);
811 -- Ada 2005 (AI-231): Assignment to not null variable
813 if Ada_Version
>= Ada_2005
814 and then Can_Never_Be_Null
(T1
)
815 and then not Assignment_OK
(Lhs
)
817 -- Case where we know the right hand side is null
819 if Known_Null
(Rhs
) then
820 Apply_Compile_Time_Constraint_Error
823 "(Ada 2005) NULL not allowed in null-excluding objects??",
824 Reason
=> CE_Null_Not_Allowed
);
826 -- We still mark this as a possible modification, that's necessary
827 -- to reset Is_True_Constant, and desirable for xref purposes.
829 Note_Possible_Modification
(Lhs
, Sure
=> True);
832 -- If we know the right hand side is non-null, then we convert to the
833 -- target type, since we don't need a run time check in that case.
835 elsif not Can_Never_Be_Null
(T2
) then
836 Rewrite
(Rhs
, Convert_To
(T1
, Relocate_Node
(Rhs
)));
837 Analyze_And_Resolve
(Rhs
, T1
);
841 if Is_Scalar_Type
(T1
) then
844 function Omit_Range_Check_For_Streaming
return Boolean;
845 -- Return True if this assignment statement is the expansion of
846 -- a Some_Scalar_Type'Read procedure call such that all conditions
847 -- of 13.3.2(35)'s "no check is made" rule are met.
849 ------------------------------------
850 -- Omit_Range_Check_For_Streaming --
851 ------------------------------------
853 function Omit_Range_Check_For_Streaming
return Boolean is
855 -- Have we got an implicitly generated assignment to a
856 -- component of a composite object? If not, return False.
858 if Comes_From_Source
(N
)
859 or else Serious_Errors_Detected
> 0
861 not in N_Selected_Component | N_Indexed_Component
867 Pref
: constant Node_Id
:= Prefix
(Lhs
);
869 -- Are we in the implicitly-defined Read subprogram
870 -- for a composite type, reading the value of a scalar
871 -- component from the stream? If not, return False.
873 if Nkind
(Pref
) /= N_Identifier
874 or else not Is_TSS
(Scope
(Entity
(Pref
)), TSS_Stream_Read
)
879 -- Return False if Default_Value or Default_Component_Value
882 if Has_Default_Aspect
(Etype
(Lhs
))
883 or else Has_Default_Aspect
(Etype
(Pref
))
887 -- Are we assigning to a record component (as opposed to
888 -- an array component)?
890 elsif Nkind
(Lhs
) = N_Selected_Component
then
892 -- Are we assigning to a nondiscriminant component
893 -- that lacks a default initial value expression?
894 -- If so, return True.
897 Comp_Id
: constant Entity_Id
:=
898 Original_Record_Component
899 (Entity
(Selector_Name
(Lhs
)));
901 if Ekind
(Comp_Id
) = E_Component
902 and then Nkind
(Parent
(Comp_Id
))
903 = N_Component_Declaration
904 and then No
(Expression
(Parent
(Comp_Id
)))
911 -- We are assigning to a component of an array
912 -- (and we tested for both Default_Value and
913 -- Default_Component_Value above), so return True.
916 pragma Assert
(Nkind
(Lhs
) = N_Indexed_Component
);
920 end Omit_Range_Check_For_Streaming
;
923 if not Omit_Range_Check_For_Streaming
then
924 Apply_Scalar_Range_Check
(Rhs
, Etype
(Lhs
));
928 -- For array types, verify that lengths match. If the right hand side
929 -- is a function call that has been inlined, the assignment has been
930 -- rewritten as a block, and the constraint check will be applied to the
931 -- assignment within the block.
933 elsif Is_Array_Type
(T1
)
934 and then (Nkind
(Rhs
) /= N_Type_Conversion
935 or else Is_Constrained
(Etype
(Rhs
)))
936 and then (Nkind
(Rhs
) /= N_Function_Call
937 or else Nkind
(N
) /= N_Block_Statement
)
939 -- Assignment verifies that the length of the Lhs and Rhs are equal,
940 -- but of course the indexes do not have to match. If the right-hand
941 -- side is a type conversion to an unconstrained type, a length check
942 -- is performed on the expression itself during expansion. In rare
943 -- cases, the redundant length check is computed on an index type
944 -- with a different representation, triggering incorrect code in the
947 Apply_Length_Check_On_Assignment
(Rhs
, Etype
(Lhs
), Lhs
);
950 -- Discriminant checks are applied in the course of expansion
955 -- Note: modifications of the Lhs may only be recorded after
956 -- checks have been applied.
958 Note_Possible_Modification
(Lhs
, Sure
=> True);
960 -- ??? a real accessibility check is needed when ???
962 -- Post warning for redundant assignment or variable to itself
964 if Warn_On_Redundant_Constructs
966 -- We only warn for source constructs
968 and then Comes_From_Source
(N
)
970 -- Where the object is the same on both sides
972 and then Same_Object
(Lhs
, Rhs
)
974 -- But exclude the case where the right side was an operation that
975 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
976 -- don't want to warn in such a case, since it is reasonable to write
977 -- such expressions especially when K is defined symbolically in some
980 and then Nkind
(Original_Node
(Rhs
)) not in N_Op
982 if Nkind
(Lhs
) in N_Has_Entity
then
983 Error_Msg_NE
-- CODEFIX
984 ("?r?useless assignment of & to itself!", N
, Entity
(Lhs
));
986 Error_Msg_N
-- CODEFIX
987 ("?r?useless assignment of object to itself!", N
);
991 -- Check for non-allowed composite assignment
993 if not Support_Composite_Assign_On_Target
994 and then (Is_Array_Type
(T1
) or else Is_Record_Type
(T1
))
995 and then (not Has_Size_Clause
(T1
)
996 or else Esize
(T1
) > Ttypes
.System_Max_Integer_Size
)
998 Error_Msg_CRT
("composite assignment", N
);
1001 -- Check elaboration warning for left side if not in elab code
1003 if Legacy_Elaboration_Checks
1004 and not In_Subprogram_Or_Concurrent_Unit
1006 Check_Elab_Assign
(Lhs
);
1009 -- Save the scenario for later examination by the ABE Processing phase
1011 Record_Elaboration_Scenario
(N
);
1013 -- Set Referenced_As_LHS if appropriate. We are not interested in
1014 -- compiler-generated assignment statements, nor in references outside
1015 -- the extended main source unit. We check whether the Original_Node is
1016 -- in the extended main source unit because in the case of a renaming of
1017 -- a component of a packed array, the Lhs itself has a Sloc from the
1018 -- place of the renaming.
1020 if Comes_From_Source
(N
)
1021 and then (In_Extended_Main_Source_Unit
(Lhs
)
1022 or else In_Extended_Main_Source_Unit
(Original_Node
(Lhs
)))
1024 Set_Referenced_Modified
(Lhs
, Out_Param
=> False);
1027 -- RM 7.3.2 (12/3): An assignment to a view conversion (from a type to
1028 -- one of its ancestors) requires an invariant check. Apply check only
1029 -- if expression comes from source, otherwise it will be applied when
1030 -- value is assigned to source entity. This is not done in GNATprove
1031 -- mode, as GNATprove handles invariant checks itself.
1033 if Nkind
(Lhs
) = N_Type_Conversion
1034 and then Has_Invariants
(Etype
(Expression
(Lhs
)))
1035 and then Comes_From_Source
(Expression
(Lhs
))
1036 and then not GNATprove_Mode
1038 Insert_After
(N
, Make_Invariant_Call
(Expression
(Lhs
)));
1041 -- Final step. If left side is an entity, then we may be able to reset
1042 -- the current tracked values to new safe values. We only have something
1043 -- to do if the left side is an entity name, and expansion has not
1044 -- modified the node into something other than an assignment, and of
1045 -- course we only capture values if it is safe to do so.
1047 if Is_Entity_Name
(Lhs
)
1048 and then Nkind
(N
) = N_Assignment_Statement
1051 Ent
: constant Entity_Id
:= Entity
(Lhs
);
1054 if Safe_To_Capture_Value
(N
, Ent
) then
1056 -- If simple variable on left side, warn if this assignment
1057 -- blots out another one (rendering it useless). We only do
1058 -- this for source assignments, otherwise we can generate bogus
1059 -- warnings when an assignment is rewritten as another
1060 -- assignment, and gets tied up with itself.
1062 -- We also omit the warning if the RHS includes target names,
1063 -- that is to say the Ada 2022 "@" that denotes an instance of
1064 -- the LHS, which indicates that the current value is being
1065 -- used. Note that this implicit reference to the entity on
1066 -- the RHS is not treated as a source reference.
1068 -- There may have been a previous reference to a component of
1069 -- the variable, which in general removes the Last_Assignment
1070 -- field of the variable to indicate a relevant use of the
1071 -- previous assignment.
1073 if Warn_On_Modified_Unread
1074 and then Is_Assignable
(Ent
)
1075 and then Comes_From_Source
(N
)
1076 and then In_Extended_Main_Source_Unit
(Ent
)
1077 and then not Has_Target_Names
(N
)
1079 Warn_On_Useless_Assignment
(Ent
, N
);
1082 -- If we are assigning an access type and the left side is an
1083 -- entity, then make sure that the Is_Known_[Non_]Null flags
1084 -- properly reflect the state of the entity after assignment.
1086 if Is_Access_Type
(T1
) then
1087 if Known_Non_Null
(Rhs
) then
1088 Set_Is_Known_Non_Null
(Ent
, True);
1090 elsif Known_Null
(Rhs
)
1091 and then not Can_Never_Be_Null
(Ent
)
1093 Set_Is_Known_Null
(Ent
, True);
1096 Set_Is_Known_Null
(Ent
, False);
1098 if not Can_Never_Be_Null
(Ent
) then
1099 Set_Is_Known_Non_Null
(Ent
, False);
1103 -- For discrete types, we may be able to set the current value
1104 -- if the value is known at compile time.
1106 elsif Is_Discrete_Type
(T1
)
1107 and then Compile_Time_Known_Value
(Rhs
)
1109 Set_Current_Value
(Ent
, Rhs
);
1111 Set_Current_Value
(Ent
, Empty
);
1114 -- If not safe to capture values, kill them
1122 -- If assigning to an object in whole or in part, note location of
1123 -- assignment in case no one references value. We only do this for
1124 -- source assignments, otherwise we can generate bogus warnings when an
1125 -- assignment is rewritten as another assignment, and gets tied up with
1129 Ent
: constant Entity_Id
:= Get_Enclosing_Object
(Lhs
);
1132 and then Safe_To_Capture_Value
(N
, Ent
)
1133 and then Nkind
(N
) = N_Assignment_Statement
1134 and then Warn_On_Modified_Unread
1135 and then Is_Assignable
(Ent
)
1136 and then Comes_From_Source
(N
)
1137 and then In_Extended_Main_Source_Unit
(Ent
)
1139 Set_Last_Assignment
(Ent
, Lhs
);
1143 Analyze_Dimension
(N
);
1146 Restore_Ghost_Region
(Saved_GM
, Saved_IGR
);
1148 -- If the right-hand side contains target names, expansion has been
1149 -- disabled to prevent expansion that might move target names out of
1150 -- the context of the assignment statement. Restore the expander mode
1151 -- now so that assignment statement can be properly expanded.
1153 if Nkind
(N
) = N_Assignment_Statement
then
1154 if Has_Target_Names
(N
) then
1155 Expander_Mode_Restore
;
1156 Full_Analysis
:= Save_Full_Analysis
;
1157 Current_Assignment
:= Empty
;
1160 end Analyze_Assignment
;
1162 -----------------------------
1163 -- Analyze_Block_Statement --
1164 -----------------------------
1166 procedure Analyze_Block_Statement
(N
: Node_Id
) is
1167 procedure Install_Return_Entities
(Scop
: Entity_Id
);
1168 -- Install all entities of return statement scope Scop in the visibility
1169 -- chain except for the return object since its entity is reused in a
1172 -----------------------------
1173 -- Install_Return_Entities --
1174 -----------------------------
1176 procedure Install_Return_Entities
(Scop
: Entity_Id
) is
1180 Id
:= First_Entity
(Scop
);
1181 while Present
(Id
) loop
1183 -- Do not install the return object
1185 if Ekind
(Id
) not in E_Constant | E_Variable
1186 or else not Is_Return_Object
(Id
)
1188 Install_Entity
(Id
);
1193 end Install_Return_Entities
;
1195 -- Local constants and variables
1197 Decls
: constant List_Id
:= Declarations
(N
);
1198 Id
: constant Node_Id
:= Identifier
(N
);
1199 HSS
: constant Node_Id
:= Handled_Statement_Sequence
(N
);
1201 Is_BIP_Return_Statement
: Boolean;
1203 -- Start of processing for Analyze_Block_Statement
1206 -- If no handled statement sequence is present, things are really messed
1207 -- up, and we just return immediately (defence against previous errors).
1210 Check_Error_Detected
;
1214 -- Detect whether the block is actually a rewritten return statement of
1215 -- a build-in-place function.
1217 Is_BIP_Return_Statement
:=
1219 and then Present
(Entity
(Id
))
1220 and then Ekind
(Entity
(Id
)) = E_Return_Statement
1221 and then Is_Build_In_Place_Function
1222 (Return_Applies_To
(Entity
(Id
)));
1224 -- Normal processing with HSS present
1227 EH
: constant List_Id
:= Exception_Handlers
(HSS
);
1228 Ent
: Entity_Id
:= Empty
;
1231 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1232 -- Recursively save value of this global, will be restored on exit
1235 -- Initialize unblocked exit count for statements of begin block
1236 -- plus one for each exception handler that is present.
1238 Unblocked_Exit_Count
:= 1 + List_Length
(EH
);
1240 -- If a label is present analyze it and mark it as referenced
1242 if Present
(Id
) then
1246 -- An error defense. If we have an identifier, but no entity, then
1247 -- something is wrong. If previous errors, then just remove the
1248 -- identifier and continue, otherwise raise an exception.
1251 Check_Error_Detected
;
1252 Set_Identifier
(N
, Empty
);
1255 if Ekind
(Ent
) = E_Label
then
1256 Reinit_Field_To_Zero
(Ent
, F_Enclosing_Scope
);
1259 Mutate_Ekind
(Ent
, E_Block
);
1260 Generate_Reference
(Ent
, N
, ' ');
1261 Generate_Definition
(Ent
);
1263 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
1264 Set_Label_Construct
(Parent
(Ent
), N
);
1269 -- If no entity set, create a label entity
1272 Ent
:= New_Internal_Entity
(E_Block
, Current_Scope
, Sloc
(N
), 'B');
1273 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Sloc
(N
)));
1274 Set_Parent
(Ent
, N
);
1277 Set_Etype
(Ent
, Standard_Void_Type
);
1278 Set_Block_Node
(Ent
, Identifier
(N
));
1281 -- The block served as an extended return statement. Ensure that any
1282 -- entities created during the analysis and expansion of the return
1283 -- object declaration are once again visible.
1285 if Is_BIP_Return_Statement
then
1286 Install_Return_Entities
(Ent
);
1289 if Present
(Decls
) then
1290 Analyze_Declarations
(Decls
);
1292 Inspect_Deferred_Constant_Completion
(Decls
);
1296 Process_End_Label
(HSS
, 'e', Ent
);
1298 -- If exception handlers are present, then we indicate that enclosing
1299 -- scopes contain a block with handlers. We only need to mark non-
1302 if Present
(EH
) then
1305 Set_Has_Nested_Block_With_Handler
(S
);
1306 exit when Is_Overloadable
(S
)
1307 or else Ekind
(S
) = E_Package
1308 or else Is_Generic_Unit
(S
);
1313 Check_References
(Ent
);
1314 Update_Use_Clause_Chain
;
1317 if Unblocked_Exit_Count
= 0 then
1318 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1319 Check_Unreachable_Code
(N
);
1321 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1324 end Analyze_Block_Statement
;
1326 --------------------------------
1327 -- Analyze_Compound_Statement --
1328 --------------------------------
1330 procedure Analyze_Compound_Statement
(N
: Node_Id
) is
1332 Analyze_List
(Actions
(N
));
1333 end Analyze_Compound_Statement
;
1335 ----------------------------
1336 -- Analyze_Case_Statement --
1337 ----------------------------
1339 procedure Analyze_Case_Statement
(N
: Node_Id
) is
1340 Exp
: constant Node_Id
:= Expression
(N
);
1342 Statements_Analyzed
: Boolean := False;
1343 -- Set True if at least some statement sequences get analyzed. If False
1344 -- on exit, means we had a serious error that prevented full analysis of
1345 -- the case statement, and as a result it is not a good idea to output
1346 -- warning messages about unreachable code.
1348 Is_General_Case_Statement
: Boolean := False;
1349 -- Set True (later) if type of case expression is not discrete
1351 procedure Non_Static_Choice_Error
(Choice
: Node_Id
);
1352 -- Error routine invoked by the generic instantiation below when the
1353 -- case statement has a non static choice.
1355 procedure Process_Statements
(Alternative
: Node_Id
);
1356 -- Analyzes the statements associated with a case alternative. Needed
1357 -- by instantiation below.
1359 package Analyze_Case_Choices
is new
1360 Generic_Analyze_Choices
1361 (Process_Associated_Node
=> Process_Statements
);
1362 use Analyze_Case_Choices
;
1363 -- Instantiation of the generic choice analysis package
1365 package Check_Case_Choices
is new
1366 Generic_Check_Choices
1367 (Process_Empty_Choice
=> No_OP
,
1368 Process_Non_Static_Choice
=> Non_Static_Choice_Error
,
1369 Process_Associated_Node
=> No_OP
);
1370 use Check_Case_Choices
;
1371 -- Instantiation of the generic choice processing package
1373 -----------------------------
1374 -- Non_Static_Choice_Error --
1375 -----------------------------
1377 procedure Non_Static_Choice_Error
(Choice
: Node_Id
) is
1379 Flag_Non_Static_Expr
1380 ("choice given in case statement is not static!", Choice
);
1381 end Non_Static_Choice_Error
;
1383 ------------------------
1384 -- Process_Statements --
1385 ------------------------
1387 procedure Process_Statements
(Alternative
: Node_Id
) is
1388 Choices
: constant List_Id
:= Discrete_Choices
(Alternative
);
1392 if Is_General_Case_Statement
then
1394 -- Processing deferred in this case; decls associated with
1395 -- pattern match bindings don't exist yet.
1398 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1399 Statements_Analyzed
:= True;
1401 -- An interesting optimization. If the case statement expression
1402 -- is a simple entity, then we can set the current value within an
1403 -- alternative if the alternative has one possible value.
1407 -- when 2 | 3 => beta
1408 -- when others => gamma
1410 -- Here we know that N is initially 1 within alpha, but for beta and
1411 -- gamma, we do not know anything more about the initial value.
1413 if Is_Entity_Name
(Exp
) then
1414 Ent
:= Entity
(Exp
);
1416 if Is_Object
(Ent
) then
1417 if List_Length
(Choices
) = 1
1418 and then Nkind
(First
(Choices
)) in N_Subexpr
1419 and then Compile_Time_Known_Value
(First
(Choices
))
1421 Set_Current_Value
(Entity
(Exp
), First
(Choices
));
1424 Analyze_Statements
(Statements
(Alternative
));
1426 -- After analyzing the case, set the current value to empty
1427 -- since we won't know what it is for the next alternative
1428 -- (unless reset by this same circuit), or after the case.
1430 Set_Current_Value
(Entity
(Exp
), Empty
);
1435 -- Case where expression is not an entity name of an object
1437 Analyze_Statements
(Statements
(Alternative
));
1438 end Process_Statements
;
1442 Exp_Type
: Entity_Id
;
1443 Exp_Btype
: Entity_Id
;
1445 Others_Present
: Boolean;
1446 -- Indicates if Others was present
1448 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1449 -- Recursively save value of this global, will be restored on exit
1451 -- Start of processing for Analyze_Case_Statement
1456 -- The expression must be of any discrete type. In rare cases, the
1457 -- expander constructs a case statement whose expression has a private
1458 -- type whose full view is discrete. This can happen when generating
1459 -- a stream operation for a variant type after the type is frozen,
1460 -- when the partial of view of the type of the discriminant is private.
1461 -- In that case, use the full view to analyze case alternatives.
1463 if not Is_Overloaded
(Exp
)
1464 and then not Comes_From_Source
(N
)
1465 and then Is_Private_Type
(Etype
(Exp
))
1466 and then Present
(Full_View
(Etype
(Exp
)))
1467 and then Is_Discrete_Type
(Full_View
(Etype
(Exp
)))
1470 Exp_Type
:= Full_View
(Etype
(Exp
));
1472 -- For Ada, overloading might be ok because subsequently filtering
1473 -- out non-discretes may resolve the ambiguity.
1474 -- But GNAT extensions allow casing on non-discretes.
1476 elsif Core_Extensions_Allowed
and then Is_Overloaded
(Exp
) then
1478 -- It would be nice if we could generate all the right error
1479 -- messages by calling "Resolve (Exp, Any_Type);" in the
1480 -- same way that they are generated a few lines below by the
1481 -- call "Analyze_And_Resolve (Exp, Any_Discrete);".
1482 -- Unfortunately, Any_Type and Any_Discrete are not treated
1483 -- consistently (specifically, by Sem_Type.Covers), so that
1487 ("selecting expression of general case statement is ambiguous",
1491 -- Check for a GNAT-extension "general" case statement (i.e., one where
1492 -- the type of the selecting expression is not discrete).
1494 elsif Core_Extensions_Allowed
1495 and then not Is_Discrete_Type
(Etype
(Exp
))
1497 Resolve
(Exp
, Etype
(Exp
));
1498 Exp_Type
:= Etype
(Exp
);
1499 Is_General_Case_Statement
:= True;
1501 Analyze_And_Resolve
(Exp
, Any_Discrete
);
1502 Exp_Type
:= Etype
(Exp
);
1505 Check_Unset_Reference
(Exp
);
1506 Exp_Btype
:= Base_Type
(Exp_Type
);
1508 -- The expression must be of a discrete type which must be determinable
1509 -- independently of the context in which the expression occurs, but
1510 -- using the fact that the expression must be of a discrete type.
1511 -- Moreover, the type this expression must not be a character literal
1512 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1514 -- If error already reported by Resolve, nothing more to do
1516 if Exp_Btype
= Any_Discrete
or else Exp_Btype
= Any_Type
then
1519 elsif Exp_Btype
= Any_Character
then
1521 ("character literal as case expression is ambiguous", Exp
);
1524 elsif Ada_Version
= Ada_83
1525 and then (Is_Generic_Type
(Exp_Btype
)
1526 or else Is_Generic_Type
(Root_Type
(Exp_Btype
)))
1529 ("(Ada 83) case expression cannot be of a generic type", Exp
);
1532 elsif not Core_Extensions_Allowed
1533 and then not Is_Discrete_Type
(Exp_Type
)
1536 ("expression in case statement must be of a discrete_Type", Exp
);
1540 -- If the case expression is a formal object of mode in out, then treat
1541 -- it as having a nonstatic subtype by forcing use of the base type
1542 -- (which has to get passed to Check_Case_Choices below). Also use base
1543 -- type when the case expression is parenthesized.
1545 if Paren_Count
(Exp
) > 0
1546 or else (Is_Entity_Name
(Exp
)
1547 and then Ekind
(Entity
(Exp
)) = E_Generic_In_Out_Parameter
)
1549 Exp_Type
:= Exp_Btype
;
1552 -- Call instantiated procedures to analyze and check discrete choices
1554 Unblocked_Exit_Count
:= 0;
1556 Analyze_Choices
(Alternatives
(N
), Exp_Type
);
1557 Check_Choices
(N
, Alternatives
(N
), Exp_Type
, Others_Present
);
1559 if Is_General_Case_Statement
then
1560 -- Work normally done in Process_Statements was deferred; do that
1561 -- deferred work now that Check_Choices has had a chance to create
1562 -- any needed pattern-match-binding declarations.
1564 Alt
: Node_Id
:= First
(Alternatives
(N
));
1566 while Present
(Alt
) loop
1567 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1568 Analyze_Statements
(Statements
(Alt
));
1574 if Exp_Type
= Universal_Integer
and then not Others_Present
then
1575 Error_Msg_N
("case on universal integer requires OTHERS choice", Exp
);
1578 -- If all our exits were blocked by unconditional transfers of control,
1579 -- then the entire CASE statement acts as an unconditional transfer of
1580 -- control, so treat it like one, and check unreachable code. Skip this
1581 -- test if we had serious errors preventing any statement analysis.
1583 if Unblocked_Exit_Count
= 0 and then Statements_Analyzed
then
1584 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1585 Check_Unreachable_Code
(N
);
1587 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1590 -- If the expander is active it will detect the case of a statically
1591 -- determined single alternative and remove warnings for the case, but
1592 -- if we are not doing expansion, that circuit won't be active. Here we
1593 -- duplicate the effect of removing warnings in the same way, so that
1594 -- we will get the same set of warnings in -gnatc mode.
1596 if not Expander_Active
1597 and then Compile_Time_Known_Value
(Expression
(N
))
1598 and then Serious_Errors_Detected
= 0
1601 Chosen
: constant Node_Id
:= Find_Static_Alternative
(N
);
1605 Alt
:= First
(Alternatives
(N
));
1606 while Present
(Alt
) loop
1607 if Alt
/= Chosen
then
1608 Remove_Warning_Messages
(Statements
(Alt
));
1615 end Analyze_Case_Statement
;
1617 ----------------------------
1618 -- Analyze_Exit_Statement --
1619 ----------------------------
1621 -- If the exit includes a name, it must be the name of a currently open
1622 -- loop. Otherwise there must be an innermost open loop on the stack, to
1623 -- which the statement implicitly refers.
1625 -- Additionally, in SPARK mode:
1627 -- The exit can only name the closest enclosing loop;
1629 -- An exit with a when clause must be directly contained in a loop;
1631 -- An exit without a when clause must be directly contained in an
1632 -- if-statement with no elsif or else, which is itself directly contained
1633 -- in a loop. The exit must be the last statement in the if-statement.
1635 procedure Analyze_Exit_Statement
(N
: Node_Id
) is
1636 Target
: constant Node_Id
:= Name
(N
);
1637 Cond
: constant Node_Id
:= Condition
(N
);
1638 Scope_Id
: Entity_Id
:= Empty
; -- initialize to prevent warning
1644 Check_Unreachable_Code
(N
);
1647 if Present
(Target
) then
1649 U_Name
:= Entity
(Target
);
1651 if not In_Open_Scopes
(U_Name
) or else Ekind
(U_Name
) /= E_Loop
then
1652 Error_Msg_N
("invalid loop name in exit statement", N
);
1656 Set_Has_Exit
(U_Name
);
1663 for J
in reverse 0 .. Scope_Stack
.Last
loop
1664 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1665 Kind
:= Ekind
(Scope_Id
);
1667 if Kind
= E_Loop
and then (No
(Target
) or else Scope_Id
= U_Name
) then
1668 Set_Has_Exit
(Scope_Id
);
1671 elsif Kind
= E_Block
1672 or else Kind
= E_Loop
1673 or else Kind
= E_Return_Statement
1679 ("cannot exit from program unit or accept statement", N
);
1684 -- Verify that if present the condition is a Boolean expression
1686 if Present
(Cond
) then
1687 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1688 Check_Unset_Reference
(Cond
);
1691 -- Chain exit statement to associated loop entity
1693 Set_Next_Exit_Statement
(N
, First_Exit_Statement
(Scope_Id
));
1694 Set_First_Exit_Statement
(Scope_Id
, N
);
1696 -- Since the exit may take us out of a loop, any previous assignment
1697 -- statement is not useless, so clear last assignment indications. It
1698 -- is OK to keep other current values, since if the exit statement
1699 -- does not exit, then the current values are still valid.
1701 Kill_Current_Values
(Last_Assignment_Only
=> True);
1702 end Analyze_Exit_Statement
;
1704 ----------------------------
1705 -- Analyze_Goto_Statement --
1706 ----------------------------
1708 procedure Analyze_Goto_Statement
(N
: Node_Id
) is
1709 Label
: constant Node_Id
:= Name
(N
);
1710 Scope_Id
: Entity_Id
;
1711 Label_Scope
: Entity_Id
;
1712 Label_Ent
: Entity_Id
;
1715 -- Actual semantic checks
1717 Check_Unreachable_Code
(N
);
1718 Kill_Current_Values
(Last_Assignment_Only
=> True);
1721 Label_Ent
:= Entity
(Label
);
1723 -- Ignore previous error
1725 if Label_Ent
= Any_Id
then
1726 Check_Error_Detected
;
1729 -- We just have a label as the target of a goto
1731 elsif Ekind
(Label_Ent
) /= E_Label
then
1732 Error_Msg_N
("target of goto statement must be a label", Label
);
1735 -- Check that the target of the goto is reachable according to Ada
1736 -- scoping rules. Note: the special gotos we generate for optimizing
1737 -- local handling of exceptions would violate these rules, but we mark
1738 -- such gotos as analyzed when built, so this code is never entered.
1740 elsif not Reachable
(Label_Ent
) then
1741 Error_Msg_N
("target of goto statement is not reachable", Label
);
1745 -- Here if goto passes initial validity checks
1747 Label_Scope
:= Enclosing_Scope
(Label_Ent
);
1749 for J
in reverse 0 .. Scope_Stack
.Last
loop
1750 Scope_Id
:= Scope_Stack
.Table
(J
).Entity
;
1752 if Label_Scope
= Scope_Id
1753 or else Ekind
(Scope_Id
) not in
1754 E_Block | E_Loop | E_Return_Statement
1756 if Scope_Id
/= Label_Scope
then
1758 ("cannot exit from program unit or accept statement", N
);
1765 raise Program_Error
;
1766 end Analyze_Goto_Statement
;
1768 ---------------------------------
1769 -- Analyze_Goto_When_Statement --
1770 ---------------------------------
1772 procedure Analyze_Goto_When_Statement
(N
: Node_Id
) is
1774 -- Verify the condition is a Boolean expression
1776 Analyze_And_Resolve
(Condition
(N
), Any_Boolean
);
1777 Check_Unset_Reference
(Condition
(N
));
1778 end Analyze_Goto_When_Statement
;
1780 --------------------------
1781 -- Analyze_If_Statement --
1782 --------------------------
1784 -- A special complication arises in the analysis of if statements
1786 -- The expander has circuitry to completely delete code that it can tell
1787 -- will not be executed (as a result of compile time known conditions). In
1788 -- the analyzer, we ensure that code that will be deleted in this manner
1789 -- is analyzed but not expanded. This is obviously more efficient, but
1790 -- more significantly, difficulties arise if code is expanded and then
1791 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1792 -- generated in deleted code must be frozen from start, because the nodes
1793 -- on which they depend will not be available at the freeze point.
1795 procedure Analyze_If_Statement
(N
: Node_Id
) is
1796 Save_Unblocked_Exit_Count
: constant Nat
:= Unblocked_Exit_Count
;
1797 -- Recursively save value of this global, will be restored on exit
1799 Save_In_Deleted_Code
: Boolean := In_Deleted_Code
;
1801 Del
: Boolean := False;
1802 -- This flag gets set True if a True condition has been found, which
1803 -- means that remaining ELSE/ELSIF parts are deleted.
1805 procedure Analyze_Cond_Then
(Cnode
: Node_Id
);
1806 -- This is applied to either the N_If_Statement node itself or to an
1807 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1808 -- statements associated with it.
1810 -----------------------
1811 -- Analyze_Cond_Then --
1812 -----------------------
1814 procedure Analyze_Cond_Then
(Cnode
: Node_Id
) is
1815 Cond
: constant Node_Id
:= Condition
(Cnode
);
1816 Tstm
: constant List_Id
:= Then_Statements
(Cnode
);
1819 Unblocked_Exit_Count
:= Unblocked_Exit_Count
+ 1;
1820 Analyze_And_Resolve
(Cond
, Any_Boolean
);
1821 Check_Unset_Reference
(Cond
);
1822 Set_Current_Value_Condition
(Cnode
);
1824 -- If already deleting, then just analyze then statements
1827 Analyze_Statements
(Tstm
);
1829 -- Compile time known value, not deleting yet
1831 elsif Compile_Time_Known_Value
(Cond
) then
1832 Save_In_Deleted_Code
:= In_Deleted_Code
;
1834 -- If condition is True, then analyze the THEN statements and set
1835 -- no expansion for ELSE and ELSIF parts.
1837 if Is_True
(Expr_Value
(Cond
)) then
1838 Analyze_Statements
(Tstm
);
1840 Expander_Mode_Save_And_Set
(False);
1841 In_Deleted_Code
:= True;
1843 -- If condition is False, analyze THEN with expansion off
1845 else pragma Assert
(Is_False
(Expr_Value
(Cond
)));
1846 Expander_Mode_Save_And_Set
(False);
1847 In_Deleted_Code
:= True;
1848 Analyze_Statements
(Tstm
);
1849 Expander_Mode_Restore
;
1850 In_Deleted_Code
:= Save_In_Deleted_Code
;
1853 -- Not known at compile time, not deleting, normal analysis
1856 Analyze_Statements
(Tstm
);
1858 end Analyze_Cond_Then
;
1863 -- For iterating over elsif parts
1865 -- Start of processing for Analyze_If_Statement
1868 -- Initialize exit count for else statements. If there is no else part,
1869 -- this count will stay non-zero reflecting the fact that the uncovered
1870 -- else case is an unblocked exit.
1872 Unblocked_Exit_Count
:= 1;
1873 Analyze_Cond_Then
(N
);
1875 -- Now to analyze the elsif parts if any are present
1877 E
:= First
(Elsif_Parts
(N
));
1878 while Present
(E
) loop
1879 Analyze_Cond_Then
(E
);
1883 if Present
(Else_Statements
(N
)) then
1884 Analyze_Statements
(Else_Statements
(N
));
1887 -- If all our exits were blocked by unconditional transfers of control,
1888 -- then the entire IF statement acts as an unconditional transfer of
1889 -- control, so treat it like one, and check unreachable code.
1891 if Unblocked_Exit_Count
= 0 then
1892 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1893 Check_Unreachable_Code
(N
);
1895 Unblocked_Exit_Count
:= Save_Unblocked_Exit_Count
;
1899 Expander_Mode_Restore
;
1900 In_Deleted_Code
:= Save_In_Deleted_Code
;
1903 if not Expander_Active
1904 and then Compile_Time_Known_Value
(Condition
(N
))
1905 and then Serious_Errors_Detected
= 0
1907 if Is_True
(Expr_Value
(Condition
(N
))) then
1908 Remove_Warning_Messages
(Else_Statements
(N
));
1910 E
:= First
(Elsif_Parts
(N
));
1911 while Present
(E
) loop
1912 Remove_Warning_Messages
(Then_Statements
(E
));
1917 Remove_Warning_Messages
(Then_Statements
(N
));
1921 -- Warn on redundant if statement that has no effect
1923 -- Note, we could also check empty ELSIF parts ???
1925 if Warn_On_Redundant_Constructs
1927 -- If statement must be from source
1929 and then Comes_From_Source
(N
)
1931 -- Condition must not have obvious side effect
1933 and then Has_No_Obvious_Side_Effects
(Condition
(N
))
1935 -- No elsif parts of else part
1937 and then No
(Elsif_Parts
(N
))
1938 and then No
(Else_Statements
(N
))
1940 -- Then must be a single null statement
1942 and then List_Length
(Then_Statements
(N
)) = 1
1944 -- Go to original node, since we may have rewritten something as
1945 -- a null statement (e.g. a case we could figure the outcome of).
1948 T
: constant Node_Id
:= First
(Then_Statements
(N
));
1949 S
: constant Node_Id
:= Original_Node
(T
);
1952 if Comes_From_Source
(S
) and then Nkind
(S
) = N_Null_Statement
then
1953 Error_Msg_N
("if statement has no effect?r?", N
);
1957 end Analyze_If_Statement
;
1959 ----------------------------------------
1960 -- Analyze_Implicit_Label_Declaration --
1961 ----------------------------------------
1963 -- An implicit label declaration is generated in the innermost enclosing
1964 -- declarative part. This is done for labels, and block and loop names.
1966 procedure Analyze_Implicit_Label_Declaration
(N
: Node_Id
) is
1967 Id
: constant Node_Id
:= Defining_Identifier
(N
);
1970 Mutate_Ekind
(Id
, E_Label
);
1971 Set_Etype
(Id
, Standard_Void_Type
);
1972 Set_Enclosing_Scope
(Id
, Current_Scope
);
1974 -- A label declared within a Ghost region becomes Ghost (SPARK RM
1977 if Ghost_Mode
> None
then
1978 Set_Is_Ghost_Entity
(Id
);
1980 end Analyze_Implicit_Label_Declaration
;
1982 ------------------------------
1983 -- Analyze_Iteration_Scheme --
1984 ------------------------------
1986 procedure Analyze_Iteration_Scheme
(N
: Node_Id
) is
1988 Iter_Spec
: Node_Id
;
1989 Loop_Spec
: Node_Id
;
1992 -- For an infinite loop, there is no iteration scheme
1998 Cond
:= Condition
(N
);
1999 Iter_Spec
:= Iterator_Specification
(N
);
2000 Loop_Spec
:= Loop_Parameter_Specification
(N
);
2002 if Present
(Cond
) then
2003 Analyze_And_Resolve
(Cond
, Any_Boolean
);
2004 Check_Unset_Reference
(Cond
);
2005 Set_Current_Value_Condition
(N
);
2007 elsif Present
(Iter_Spec
) then
2008 Analyze_Iterator_Specification
(Iter_Spec
);
2011 Analyze_Loop_Parameter_Specification
(Loop_Spec
);
2013 end Analyze_Iteration_Scheme
;
2015 ------------------------------------
2016 -- Analyze_Iterator_Specification --
2017 ------------------------------------
2019 procedure Analyze_Iterator_Specification
(N
: Node_Id
) is
2020 Def_Id
: constant Node_Id
:= Defining_Identifier
(N
);
2021 Iter_Name
: constant Node_Id
:= Name
(N
);
2022 Loc
: constant Source_Ptr
:= Sloc
(N
);
2023 Subt
: constant Node_Id
:= Subtype_Indication
(N
);
2025 Bas
: Entity_Id
:= Empty
; -- initialize to prevent warning
2028 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
);
2029 -- For an iteration over a container, if the loop carries the Reverse
2030 -- indicator, verify that the container type has an Iterate aspect that
2031 -- implements the reversible iterator interface.
2033 procedure Check_Subtype_Definition
(Comp_Type
: Entity_Id
);
2034 -- If a subtype indication is present, verify that it is consistent
2035 -- with the component type of the array or container name.
2036 -- In Ada 2022, the subtype indication may be an access definition,
2037 -- if the array or container has elements of an anonymous access type.
2039 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
;
2040 -- For containers with Iterator and related aspects, the cursor is
2041 -- obtained by locating an entity with the proper name in the scope
2044 -----------------------------
2045 -- Check_Reverse_Iteration --
2046 -----------------------------
2048 procedure Check_Reverse_Iteration
(Typ
: Entity_Id
) is
2050 if Reverse_Present
(N
) then
2051 if Is_Array_Type
(Typ
)
2052 or else Is_Reversible_Iterator
(Typ
)
2054 (Has_Aspect
(Typ
, Aspect_Iterable
)
2057 (Get_Iterable_Type_Primitive
(Typ
, Name_Previous
)))
2062 ("container type does not support reverse iteration", N
);
2065 end Check_Reverse_Iteration
;
2067 -------------------------------
2068 -- Check_Subtype_Definition --
2069 -------------------------------
2071 procedure Check_Subtype_Definition
(Comp_Type
: Entity_Id
) is
2077 if Is_Anonymous_Access_Type
(Entity
(Subt
)) then
2078 if not Is_Anonymous_Access_Type
(Comp_Type
) then
2080 ("component type& is not an anonymous access",
2083 elsif not Conforming_Types
2084 (Designated_Type
(Entity
(Subt
)),
2085 Designated_Type
(Comp_Type
),
2089 ("subtype indication does not match component type&",
2093 elsif not Covers
(Base_Type
(Bas
), Comp_Type
)
2094 or else not Subtypes_Statically_Match
(Bas
, Comp_Type
)
2096 if Is_Array_Type
(Typ
) then
2098 ("subtype indication does not match component type&",
2102 ("subtype indication does not match element type&",
2106 end Check_Subtype_Definition
;
2108 ---------------------
2109 -- Get_Cursor_Type --
2110 ---------------------
2112 function Get_Cursor_Type
(Typ
: Entity_Id
) return Entity_Id
is
2116 -- If the iterator type is derived and it has an iterator interface
2117 -- type as an ancestor, then the cursor type is declared in the scope
2118 -- of that interface type.
2120 if Is_Derived_Type
(Typ
) then
2122 Iter_Iface
: constant Entity_Id
:=
2123 Iterator_Interface_Ancestor
(Typ
);
2126 if Present
(Iter_Iface
) then
2127 Ent
:= First_Entity
(Scope
(Iter_Iface
));
2129 -- If there's not an iterator interface, then retrieve the
2130 -- scope associated with the parent type and start from its
2134 Ent
:= First_Entity
(Scope
(Etype
(Typ
)));
2139 Ent
:= First_Entity
(Scope
(Typ
));
2142 while Present
(Ent
) loop
2143 exit when Chars
(Ent
) = Name_Cursor
;
2151 -- The cursor is the target of generated assignments in the
2152 -- loop, and cannot have a limited type.
2154 if Is_Limited_Type
(Etype
(Ent
)) then
2155 Error_Msg_N
("cursor type cannot be limited", N
);
2159 end Get_Cursor_Type
;
2161 -- Start of processing for Analyze_Iterator_Specification
2164 Enter_Name
(Def_Id
);
2166 -- AI12-0151 specifies that when the subtype indication is present, it
2167 -- must statically match the type of the array or container element.
2168 -- To simplify this check, we introduce a subtype declaration with the
2169 -- given subtype indication when it carries a constraint, and rewrite
2170 -- the original as a reference to the created subtype entity.
2172 if Present
(Subt
) then
2173 if Nkind
(Subt
) = N_Subtype_Indication
then
2175 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
2176 Decl
: constant Node_Id
:=
2177 Make_Subtype_Declaration
(Loc
,
2178 Defining_Identifier
=> S
,
2179 Subtype_Indication
=> New_Copy_Tree
(Subt
));
2181 Insert_Action
(N
, Decl
);
2183 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
2186 -- Ada 2022: the subtype definition may be for an anonymous
2189 elsif Nkind
(Subt
) = N_Access_Definition
then
2191 S
: constant Entity_Id
:= Make_Temporary
(Sloc
(Subt
), 'S');
2194 if Present
(Subtype_Mark
(Subt
)) then
2196 Make_Full_Type_Declaration
(Loc
,
2197 Defining_Identifier
=> S
,
2199 Make_Access_To_Object_Definition
(Loc
,
2200 All_Present
=> True,
2201 Subtype_Indication
=>
2202 New_Copy_Tree
(Subtype_Mark
(Subt
))));
2206 Make_Full_Type_Declaration
(Loc
,
2207 Defining_Identifier
=> S
,
2210 (Access_To_Subprogram_Definition
(Subt
)));
2213 Insert_Before
(Parent
(Parent
(N
)), Decl
);
2215 Freeze_Before
(First
(Statements
(Parent
(Parent
(N
)))), S
);
2216 Rewrite
(Subt
, New_Occurrence_Of
(S
, Sloc
(Subt
)));
2222 -- Save entity of subtype indication for subsequent check
2224 Bas
:= Entity
(Subt
);
2227 Preanalyze_Range
(Iter_Name
);
2229 -- If the domain of iteration is a function call, make sure the function
2230 -- itself is frozen. This is an issue if this is a local expression
2233 if Nkind
(Iter_Name
) = N_Function_Call
2234 and then Is_Entity_Name
(Name
(Iter_Name
))
2235 and then Full_Analysis
2236 and then (In_Assertion_Expr
= 0 or else Assertions_Enabled
)
2238 Freeze_Before
(N
, Entity
(Name
(Iter_Name
)));
2241 -- Set the kind of the loop variable, which is not visible within the
2244 Mutate_Ekind
(Def_Id
, E_Variable
);
2245 Set_Is_Not_Self_Hidden
(Def_Id
);
2247 -- Provide a link between the iterator variable and the container, for
2248 -- subsequent use in cross-reference and modification information.
2250 if Of_Present
(N
) then
2251 Set_Related_Expression
(Def_Id
, Iter_Name
);
2253 -- For a container, the iterator is specified through the aspect
2255 if not Is_Array_Type
(Etype
(Iter_Name
)) then
2257 Iterator
: constant Entity_Id
:=
2258 Find_Value_Of_Aspect
2259 (Etype
(Iter_Name
), Aspect_Default_Iterator
);
2265 -- The domain of iteration must implement either the RM
2266 -- iterator interface, or the SPARK Iterable aspect.
2268 if No
(Iterator
) then
2269 if No
(Find_Aspect
(Etype
(Iter_Name
), Aspect_Iterable
)) then
2271 ("cannot iterate over&",
2272 N
, Base_Type
(Etype
(Iter_Name
)));
2276 elsif not Is_Overloaded
(Iterator
) then
2277 Check_Reverse_Iteration
(Etype
(Iterator
));
2279 -- If Iterator is overloaded, use reversible iterator if one is
2282 elsif Is_Overloaded
(Iterator
) then
2283 Get_First_Interp
(Iterator
, I
, It
);
2284 while Present
(It
.Nam
) loop
2285 if Ekind
(It
.Nam
) = E_Function
2286 and then Is_Reversible_Iterator
(Etype
(It
.Nam
))
2288 Set_Etype
(Iterator
, It
.Typ
);
2289 Set_Entity
(Iterator
, It
.Nam
);
2293 Get_Next_Interp
(I
, It
);
2296 Check_Reverse_Iteration
(Etype
(Iterator
));
2302 -- If the domain of iteration is an expression, create a declaration for
2303 -- it, so that finalization actions are introduced outside of the loop.
2304 -- The declaration must be a renaming (both in GNAT and GNATprove
2305 -- modes), because the body of the loop may assign to elements.
2307 if not Is_Entity_Name
(Iter_Name
)
2309 -- Do not perform this expansion in preanalysis
2311 and then Full_Analysis
2313 -- Do not perform this expansion when expansion is disabled, where the
2314 -- temporary may hide the transformation of a selected component into
2315 -- a prefixed function call, and references need to see the original
2318 and then (Expander_Active
or GNATprove_Mode
)
2321 Id
: constant Entity_Id
:= Make_Temporary
(Loc
, 'R', Iter_Name
);
2327 -- If the domain of iteration is an array component that depends
2328 -- on a discriminant, create actual subtype for it. Preanalysis
2329 -- does not generate the actual subtype of a selected component.
2331 if Nkind
(Iter_Name
) = N_Selected_Component
2332 and then Is_Array_Type
(Etype
(Iter_Name
))
2335 Build_Actual_Subtype_Of_Component
2336 (Etype
(Selector_Name
(Iter_Name
)), Iter_Name
);
2337 Insert_Action
(N
, Act_S
);
2339 if Present
(Act_S
) then
2340 Typ
:= Defining_Identifier
(Act_S
);
2342 Typ
:= Etype
(Iter_Name
);
2346 Typ
:= Etype
(Iter_Name
);
2348 -- Verify that the expression produces an iterator
2350 if not Of_Present
(N
) and then not Is_Iterator
(Typ
)
2351 and then not Is_Array_Type
(Typ
)
2352 and then No
(Find_Aspect
(Typ
, Aspect_Iterable
))
2355 ("expect object that implements iterator interface",
2360 -- Protect against malformed iterator
2362 if Typ
= Any_Type
then
2363 Error_Msg_N
("invalid expression in loop iterator", Iter_Name
);
2367 if not Of_Present
(N
) then
2368 Check_Reverse_Iteration
(Typ
);
2371 -- For an element iteration over a slice, we must complete
2372 -- the resolution and expansion of the slice bounds. These
2373 -- can be arbitrary expressions, and the preanalysis that
2374 -- was performed in preparation for the iteration may have
2375 -- generated an itype whose bounds must be fully expanded.
2376 -- We set the parent node to provide a proper insertion
2377 -- point for generated actions, if any.
2379 if Nkind
(Iter_Name
) = N_Slice
2380 and then Nkind
(Discrete_Range
(Iter_Name
)) = N_Range
2381 and then not Analyzed
(Discrete_Range
(Iter_Name
))
2384 Indx
: constant Node_Id
:=
2385 Entity
(First_Index
(Etype
(Iter_Name
)));
2387 Set_Parent
(Indx
, Iter_Name
);
2388 Resolve
(Scalar_Range
(Indx
), Etype
(Indx
));
2392 -- The name in the renaming declaration may be a function call.
2393 -- Indicate that it does not come from source, to suppress
2394 -- spurious warnings on renamings of parameterless functions,
2395 -- a common enough idiom in user-defined iterators.
2398 Make_Object_Renaming_Declaration
(Loc
,
2399 Defining_Identifier
=> Id
,
2400 Subtype_Mark
=> New_Occurrence_Of
(Typ
, Loc
),
2402 New_Copy_Tree
(Iter_Name
, New_Sloc
=> Loc
));
2403 Set_Comes_From_Iterator
(Decl
);
2405 Insert_Actions
(Parent
(Parent
(N
)), New_List
(Decl
));
2406 Rewrite
(Name
(N
), New_Occurrence_Of
(Id
, Loc
));
2408 Set_Etype
(Id
, Typ
);
2409 Set_Etype
(Name
(N
), Typ
);
2412 -- Container is an entity or an array with uncontrolled components, or
2413 -- else it is a container iterator given by a function call, typically
2414 -- called Iterate in the case of predefined containers, even though
2415 -- Iterate is not a reserved name. What matters is that the return type
2416 -- of the function is an iterator type.
2418 elsif Is_Entity_Name
(Iter_Name
) then
2419 Analyze
(Iter_Name
);
2421 if Nkind
(Iter_Name
) = N_Function_Call
then
2423 C
: constant Node_Id
:= Name
(Iter_Name
);
2428 if not Is_Overloaded
(Iter_Name
) then
2429 Resolve
(Iter_Name
, Etype
(C
));
2432 Get_First_Interp
(C
, I
, It
);
2433 while It
.Typ
/= Empty
loop
2434 if Reverse_Present
(N
) then
2435 if Is_Reversible_Iterator
(It
.Typ
) then
2436 Resolve
(Iter_Name
, It
.Typ
);
2440 elsif Is_Iterator
(It
.Typ
) then
2441 Resolve
(Iter_Name
, It
.Typ
);
2445 Get_Next_Interp
(I
, It
);
2450 -- Domain of iteration is not overloaded
2453 Resolve
(Iter_Name
);
2456 if not Of_Present
(N
) then
2457 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2461 -- Get base type of container, for proper retrieval of Cursor type
2462 -- and primitive operations.
2464 Typ
:= Base_Type
(Etype
(Iter_Name
));
2466 if Is_Array_Type
(Typ
) then
2467 if Of_Present
(N
) then
2468 Set_Etype
(Def_Id
, Component_Type
(Typ
));
2470 -- The loop variable is aliased if the array components are
2471 -- aliased. Likewise for the independent aspect.
2473 Set_Is_Aliased
(Def_Id
, Has_Aliased_Components
(Typ
));
2474 Set_Is_Independent
(Def_Id
, Has_Independent_Components
(Typ
));
2476 -- AI12-0047 stipulates that the domain (array or container)
2477 -- cannot be a component that depends on a discriminant if the
2478 -- enclosing object is mutable, to prevent a modification of the
2479 -- domain of iteration in the course of an iteration.
2481 -- If the object is an expression it has been captured in a
2482 -- temporary, so examine original node.
2484 if Nkind
(Original_Node
(Iter_Name
)) = N_Selected_Component
2485 and then Is_Dependent_Component_Of_Mutable_Object
2486 (Original_Node
(Iter_Name
))
2489 ("iterable name cannot be a discriminant-dependent "
2490 & "component of a mutable object", N
);
2493 Check_Subtype_Definition
(Component_Type
(Typ
));
2495 -- Here we have a missing Range attribute
2499 ("missing Range attribute in iteration over an array", N
);
2501 -- In Ada 2012 mode, this may be an attempt at an iterator
2503 if Ada_Version
>= Ada_2012
then
2505 ("\if& is meant to designate an element of the array, use OF",
2509 -- Prevent cascaded errors
2511 Mutate_Ekind
(Def_Id
, E_Loop_Parameter
);
2512 Set_Etype
(Def_Id
, Etype
(First_Index
(Typ
)));
2515 -- Check for type error in iterator
2517 elsif Typ
= Any_Type
then
2520 -- Iteration over a container
2523 Mutate_Ekind
(Def_Id
, E_Loop_Parameter
);
2524 Set_Is_Not_Self_Hidden
(Def_Id
);
2525 Error_Msg_Ada_2012_Feature
("container iterator", Sloc
(N
));
2529 if Of_Present
(N
) then
2530 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2532 Elt
: constant Entity_Id
:=
2533 Get_Iterable_Type_Primitive
(Typ
, Name_Element
);
2537 ("missing Element primitive for iteration", N
);
2539 Set_Etype
(Def_Id
, Etype
(Elt
));
2540 Check_Reverse_Iteration
(Typ
);
2544 Check_Subtype_Definition
(Etype
(Def_Id
));
2546 -- For a predefined container, the type of the loop variable is
2547 -- the Iterator_Element aspect of the container type.
2551 Element
: constant Entity_Id
:=
2552 Find_Value_Of_Aspect
2553 (Typ
, Aspect_Iterator_Element
);
2554 Iterator
: constant Entity_Id
:=
2555 Find_Value_Of_Aspect
2556 (Typ
, Aspect_Default_Iterator
);
2557 Orig_Iter_Name
: constant Node_Id
:=
2558 Original_Node
(Iter_Name
);
2559 Cursor_Type
: Entity_Id
;
2562 if No
(Element
) then
2563 Error_Msg_NE
("cannot iterate over&", N
, Typ
);
2567 Set_Etype
(Def_Id
, Entity
(Element
));
2568 Cursor_Type
:= Get_Cursor_Type
(Typ
);
2569 pragma Assert
(Present
(Cursor_Type
));
2571 Check_Subtype_Definition
(Etype
(Def_Id
));
2573 -- If the container has a variable indexing aspect, the
2574 -- element is a variable and is modifiable in the loop.
2576 if Has_Aspect
(Typ
, Aspect_Variable_Indexing
) then
2577 Mutate_Ekind
(Def_Id
, E_Variable
);
2578 Set_Is_Not_Self_Hidden
(Def_Id
);
2581 -- If the container is a constant, iterating over it
2582 -- requires a Constant_Indexing operation.
2584 if not Is_Variable
(Iter_Name
)
2585 and then not Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
2588 ("iteration over constant container require "
2589 & "constant_indexing aspect", N
);
2591 -- The Iterate function may have an in_out parameter,
2592 -- and a constant container is thus illegal.
2594 elsif Present
(Iterator
)
2595 and then Ekind
(Entity
(Iterator
)) = E_Function
2596 and then Ekind
(First_Formal
(Entity
(Iterator
))) /=
2598 and then not Is_Variable
(Iter_Name
)
2600 Error_Msg_N
("variable container expected", N
);
2603 -- Detect a case where the iterator denotes a component
2604 -- of a mutable object which depends on a discriminant.
2605 -- Note that the iterator may denote a function call in
2606 -- qualified form, in which case this check should not
2609 if Nkind
(Orig_Iter_Name
) = N_Selected_Component
2611 Present
(Entity
(Selector_Name
(Orig_Iter_Name
)))
2613 Ekind
(Entity
(Selector_Name
(Orig_Iter_Name
))) in
2614 E_Component | E_Discriminant
2615 and then Is_Dependent_Component_Of_Mutable_Object
2619 ("container cannot be a discriminant-dependent "
2620 & "component of a mutable object", N
);
2626 -- IN iterator, domain is a range, a call to Iterate function,
2627 -- or an object/actual parameter of an iterator type.
2630 -- If the type of the name is class-wide and its root type is a
2631 -- derived type, the primitive operations (First, Next, etc.) are
2632 -- those inherited by its specific type. Calls to these primitives
2633 -- will be dispatching.
2635 if Is_Class_Wide_Type
(Typ
)
2636 and then Is_Derived_Type
(Etype
(Typ
))
2641 -- For an iteration of the form IN, the name must denote an
2642 -- iterator, typically the result of a call to Iterate. Give a
2643 -- useful error message when the name is a container by itself.
2645 -- The type may be a formal container type, which has to have
2646 -- an Iterable aspect detailing the required primitives.
2648 if Is_Entity_Name
(Original_Node
(Name
(N
)))
2649 and then not Is_Iterator
(Typ
)
2651 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2654 elsif not Has_Aspect
(Typ
, Aspect_Iterator_Element
) then
2656 ("cannot iterate over&", Name
(N
), Typ
);
2659 ("name must be an iterator, not a container", Name
(N
));
2662 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2666 ("\to iterate directly over the elements of a container, "
2667 & "write `of &`", Name
(N
), Original_Node
(Name
(N
)));
2669 -- No point in continuing analysis of iterator spec
2675 -- If the name is a call (typically prefixed) to some Iterate
2676 -- function, it has been rewritten as an object declaration.
2677 -- If that object is a selected component, verify that it is not
2678 -- a component of an unconstrained mutable object.
2680 if Nkind
(Iter_Name
) = N_Identifier
2681 or else (not Expander_Active
and Comes_From_Source
(Iter_Name
))
2684 Orig_Node
: constant Node_Id
:= Original_Node
(Iter_Name
);
2685 Iter_Kind
: constant Node_Kind
:= Nkind
(Orig_Node
);
2689 if Iter_Kind
= N_Selected_Component
then
2690 Obj
:= Prefix
(Orig_Node
);
2692 elsif Iter_Kind
= N_Function_Call
then
2693 Obj
:= First_Actual
(Orig_Node
);
2695 -- If neither, the name comes from source
2701 if Nkind
(Obj
) = N_Selected_Component
2702 and then Is_Dependent_Component_Of_Mutable_Object
(Obj
)
2705 ("container cannot be a discriminant-dependent "
2706 & "component of a mutable object", N
);
2711 -- The result type of Iterate function is the classwide type of
2712 -- the interface parent. We need the specific Cursor type defined
2713 -- in the container package. We obtain it by name for a predefined
2714 -- container, or through the Iterable aspect for a formal one.
2716 if Has_Aspect
(Typ
, Aspect_Iterable
) then
2719 (Parent
(Find_Value_Of_Aspect
(Typ
, Aspect_Iterable
)),
2723 Set_Etype
(Def_Id
, Get_Cursor_Type
(Typ
));
2724 Check_Reverse_Iteration
(Etype
(Iter_Name
));
2730 -- Preanalyze the filter. Expansion will take place when enclosing
2731 -- loop is expanded.
2733 if Present
(Iterator_Filter
(N
)) then
2734 Preanalyze_And_Resolve
(Iterator_Filter
(N
), Standard_Boolean
);
2736 end Analyze_Iterator_Specification
;
2742 -- Note: the semantic work required for analyzing labels (setting them as
2743 -- reachable) was done in a prepass through the statements in the block,
2744 -- so that forward gotos would be properly handled. See Analyze_Statements
2745 -- for further details. The only processing required here is to deal with
2746 -- optimizations that depend on an assumption of sequential control flow,
2747 -- since of course the occurrence of a label breaks this assumption.
2749 procedure Analyze_Label
(N
: Node_Id
) is
2750 pragma Warnings
(Off
, N
);
2752 Kill_Current_Values
;
2755 ------------------------------------------
2756 -- Analyze_Loop_Parameter_Specification --
2757 ------------------------------------------
2759 procedure Analyze_Loop_Parameter_Specification
(N
: Node_Id
) is
2760 Loop_Nod
: constant Node_Id
:= Parent
(Parent
(N
));
2762 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
);
2763 -- If the bounds are given by a 'Range reference on a function call
2764 -- that returns a controlled array, introduce an explicit declaration
2765 -- to capture the bounds, so that the function result can be finalized
2766 -- in timely fashion.
2768 procedure Check_Predicate_Use
(T
: Entity_Id
);
2769 -- Diagnose Attempt to iterate through non-static predicate. Note that
2770 -- a type with inherited predicates may have both static and dynamic
2771 -- forms. In this case it is not sufficient to check the static
2772 -- predicate function only, look for a dynamic predicate aspect as well.
2774 procedure Process_Bounds
(R
: Node_Id
);
2775 -- If the iteration is given by a range, create temporaries and
2776 -- assignment statements block to capture the bounds and perform
2777 -- required finalization actions in case a bound includes a function
2778 -- call that uses the temporary stack. We first preanalyze a copy of
2779 -- the range in order to determine the expected type, and analyze and
2780 -- resolve the original bounds.
2782 --------------------------------------
2783 -- Check_Controlled_Array_Attribute --
2784 --------------------------------------
2786 procedure Check_Controlled_Array_Attribute
(DS
: Node_Id
) is
2788 if Nkind
(DS
) = N_Attribute_Reference
2789 and then Is_Entity_Name
(Prefix
(DS
))
2790 and then Ekind
(Entity
(Prefix
(DS
))) = E_Function
2791 and then Is_Array_Type
(Etype
(Entity
(Prefix
(DS
))))
2793 Is_Controlled
(Component_Type
(Etype
(Entity
(Prefix
(DS
)))))
2794 and then Expander_Active
2797 Loc
: constant Source_Ptr
:= Sloc
(N
);
2798 Arr
: constant Entity_Id
:= Etype
(Entity
(Prefix
(DS
)));
2799 Indx
: constant Entity_Id
:=
2800 Base_Type
(Etype
(First_Index
(Arr
)));
2801 Subt
: constant Entity_Id
:= Make_Temporary
(Loc
, 'S');
2806 Make_Subtype_Declaration
(Loc
,
2807 Defining_Identifier
=> Subt
,
2808 Subtype_Indication
=>
2809 Make_Subtype_Indication
(Loc
,
2810 Subtype_Mark
=> New_Occurrence_Of
(Indx
, Loc
),
2812 Make_Range_Constraint
(Loc
, Relocate_Node
(DS
))));
2813 Insert_Before
(Loop_Nod
, Decl
);
2817 Make_Attribute_Reference
(Loc
,
2818 Prefix
=> New_Occurrence_Of
(Subt
, Loc
),
2819 Attribute_Name
=> Attribute_Name
(DS
)));
2824 end Check_Controlled_Array_Attribute
;
2826 -------------------------
2827 -- Check_Predicate_Use --
2828 -------------------------
2830 procedure Check_Predicate_Use
(T
: Entity_Id
) is
2832 -- A predicated subtype is illegal in loops and related constructs
2833 -- if the predicate is not static, or if it is a non-static subtype
2834 -- of a statically predicated subtype.
2836 if Is_Discrete_Type
(T
)
2837 and then Has_Predicates
(T
)
2838 and then (not Has_Static_Predicate
(T
)
2839 or else not Is_Static_Subtype
(T
)
2840 or else Has_Dynamic_Predicate_Aspect
(T
)
2841 or else Has_Ghost_Predicate_Aspect
(T
))
2843 -- Seems a confusing message for the case of a static predicate
2844 -- with a non-static subtype???
2846 Bad_Predicated_Subtype_Use
2847 ("cannot use subtype& with non-static predicate for loop "
2848 & "iteration", Discrete_Subtype_Definition
(N
),
2849 T
, Suggest_Static
=> True);
2851 elsif Inside_A_Generic
2852 and then Is_Generic_Formal
(T
)
2853 and then Is_Discrete_Type
(T
)
2855 Set_No_Dynamic_Predicate_On_Actual
(T
);
2857 end Check_Predicate_Use
;
2859 --------------------
2860 -- Process_Bounds --
2861 --------------------
2863 procedure Process_Bounds
(R
: Node_Id
) is
2864 Loc
: constant Source_Ptr
:= Sloc
(N
);
2867 (Original_Bound
: Node_Id
;
2868 Analyzed_Bound
: Node_Id
;
2869 Typ
: Entity_Id
) return Node_Id
;
2870 -- Capture value of bound and return captured value
2877 (Original_Bound
: Node_Id
;
2878 Analyzed_Bound
: Node_Id
;
2879 Typ
: Entity_Id
) return Node_Id
2886 -- If the bound is a constant or an object, no need for a separate
2887 -- declaration. If the bound is the result of previous expansion
2888 -- it is already analyzed and should not be modified. Note that
2889 -- the Bound will be resolved later, if needed, as part of the
2890 -- call to Make_Index (literal bounds may need to be resolved to
2893 if Analyzed
(Original_Bound
) then
2894 return Original_Bound
;
2896 elsif Nkind
(Analyzed_Bound
) in
2897 N_Integer_Literal | N_Character_Literal
2898 or else Is_Entity_Name
(Analyzed_Bound
)
2900 Analyze_And_Resolve
(Original_Bound
, Typ
);
2901 return Original_Bound
;
2903 elsif Inside_Class_Condition_Preanalysis
then
2904 Analyze_And_Resolve
(Original_Bound
, Typ
);
2905 return Original_Bound
;
2908 -- Normally, the best approach is simply to generate a constant
2909 -- declaration that captures the bound. However, there is a nasty
2910 -- case where this is wrong. If the bound is complex, and has a
2911 -- possible use of the secondary stack, we need to generate a
2912 -- separate assignment statement to ensure the creation of a block
2913 -- which will release the secondary stack.
2915 -- We prefer the constant declaration, since it leaves us with a
2916 -- proper trace of the value, useful in optimizations that get rid
2917 -- of junk range checks.
2919 if not Has_Sec_Stack_Call
(Analyzed_Bound
) then
2920 Analyze_And_Resolve
(Original_Bound
, Typ
);
2922 -- Ensure that the bound is valid. This check should not be
2923 -- generated when the range belongs to a quantified expression
2924 -- as the construct is still not expanded into its final form.
2926 if Nkind
(Parent
(R
)) /= N_Loop_Parameter_Specification
2927 or else Nkind
(Parent
(Parent
(R
))) /= N_Quantified_Expression
2929 Ensure_Valid
(Original_Bound
);
2932 Force_Evaluation
(Original_Bound
);
2933 return Original_Bound
;
2936 Id
:= Make_Temporary
(Loc
, 'R', Original_Bound
);
2938 -- Here we make a declaration with a separate assignment
2939 -- statement, and insert before loop header.
2942 Make_Object_Declaration
(Loc
,
2943 Defining_Identifier
=> Id
,
2944 Object_Definition
=> New_Occurrence_Of
(Typ
, Loc
));
2947 Make_Assignment_Statement
(Loc
,
2948 Name
=> New_Occurrence_Of
(Id
, Loc
),
2949 Expression
=> Relocate_Node
(Original_Bound
));
2951 Insert_Actions
(Loop_Nod
, New_List
(Decl
, Assign
));
2953 -- Now that this temporary variable is initialized we decorate it
2954 -- as safe-to-reevaluate to inform to the backend that no further
2955 -- asignment will be issued and hence it can be handled as side
2956 -- effect free. Note that this decoration must be done when the
2957 -- assignment has been analyzed because otherwise it will be
2958 -- rejected (see Analyze_Assignment).
2960 Set_Is_Safe_To_Reevaluate
(Id
);
2962 Rewrite
(Original_Bound
, New_Occurrence_Of
(Id
, Loc
));
2964 if Nkind
(Assign
) = N_Assignment_Statement
then
2965 return Expression
(Assign
);
2967 return Original_Bound
;
2971 Hi
: constant Node_Id
:= High_Bound
(R
);
2972 Lo
: constant Node_Id
:= Low_Bound
(R
);
2973 R_Copy
: constant Node_Id
:= New_Copy_Tree
(R
);
2978 -- Start of processing for Process_Bounds
2981 Set_Parent
(R_Copy
, Parent
(R
));
2982 Preanalyze_Range
(R_Copy
);
2983 Typ
:= Etype
(R_Copy
);
2985 -- If the type of the discrete range is Universal_Integer, then the
2986 -- bound's type must be resolved to Integer, and any object used to
2987 -- hold the bound must also have type Integer, unless the literal
2988 -- bounds are constant-folded expressions with a user-defined type.
2990 if Typ
= Universal_Integer
then
2991 if Nkind
(Lo
) = N_Integer_Literal
2992 and then Present
(Etype
(Lo
))
2993 and then Scope
(Etype
(Lo
)) /= Standard_Standard
2997 elsif Nkind
(Hi
) = N_Integer_Literal
2998 and then Present
(Etype
(Hi
))
2999 and then Scope
(Etype
(Hi
)) /= Standard_Standard
3004 Typ
:= Standard_Integer
;
3010 New_Lo
:= One_Bound
(Lo
, Low_Bound
(R_Copy
), Typ
);
3011 New_Hi
:= One_Bound
(Hi
, High_Bound
(R_Copy
), Typ
);
3013 -- Propagate staticness to loop range itself, in case the
3014 -- corresponding subtype is static.
3016 if New_Lo
/= Lo
and then Is_OK_Static_Expression
(New_Lo
) then
3017 Rewrite
(Low_Bound
(R
), New_Copy
(New_Lo
));
3020 if New_Hi
/= Hi
and then Is_OK_Static_Expression
(New_Hi
) then
3021 Rewrite
(High_Bound
(R
), New_Copy
(New_Hi
));
3027 DS
: constant Node_Id
:= Discrete_Subtype_Definition
(N
);
3028 Id
: constant Entity_Id
:= Defining_Identifier
(N
);
3032 -- Start of processing for Analyze_Loop_Parameter_Specification
3037 -- We always consider the loop variable to be referenced, since the loop
3038 -- may be used just for counting purposes.
3040 Generate_Reference
(Id
, N
, ' ');
3042 -- Check for the case of loop variable hiding a local variable (used
3043 -- later on to give a nice warning if the hidden variable is never
3047 H
: constant Entity_Id
:= Homonym
(Id
);
3050 and then Ekind
(H
) = E_Variable
3051 and then Is_Discrete_Type
(Etype
(H
))
3052 and then Enclosing_Dynamic_Scope
(H
) = Enclosing_Dynamic_Scope
(Id
)
3054 Set_Hiding_Loop_Variable
(H
, Id
);
3058 -- Analyze the subtype definition and create temporaries for the bounds.
3059 -- Do not evaluate the range when preanalyzing a quantified expression
3060 -- because bounds expressed as function calls with side effects will be
3061 -- incorrectly replicated.
3063 if Nkind
(DS
) = N_Range
3064 and then Expander_Active
3065 and then Nkind
(Parent
(N
)) /= N_Quantified_Expression
3067 Process_Bounds
(DS
);
3069 -- Either the expander not active or the range of iteration is a subtype
3070 -- indication, an entity, or a function call that yields an aggregate or
3074 DS_Copy
:= New_Copy_Tree
(DS
);
3075 Set_Parent
(DS_Copy
, Parent
(DS
));
3076 Preanalyze_Range
(DS_Copy
);
3078 -- Ada 2012: If the domain of iteration is:
3080 -- a) a function call,
3081 -- b) an identifier that is not a type,
3082 -- c) an attribute reference 'Old (within a postcondition),
3083 -- d) an unchecked conversion or a qualified expression with
3084 -- the proper iterator type.
3086 -- then it is an iteration over a container. It was classified as
3087 -- a loop specification by the parser, and must be rewritten now
3088 -- to activate container iteration. The last case will occur within
3089 -- an expanded inlined call, where the expansion wraps an actual in
3090 -- an unchecked conversion when needed. The expression of the
3091 -- conversion is always an object.
3093 if Nkind
(DS_Copy
) = N_Function_Call
3095 or else (Is_Entity_Name
(DS_Copy
)
3096 and then not Is_Type
(Entity
(DS_Copy
)))
3098 or else (Nkind
(DS_Copy
) = N_Attribute_Reference
3099 and then Attribute_Name
(DS_Copy
) in
3100 Name_Loop_Entry | Name_Old
)
3102 or else Has_Aspect
(Etype
(DS_Copy
), Aspect_Iterable
)
3104 or else Nkind
(DS_Copy
) = N_Unchecked_Type_Conversion
3105 or else (Nkind
(DS_Copy
) = N_Qualified_Expression
3106 and then Is_Iterator
(Etype
(DS_Copy
)))
3108 -- This is an iterator specification. Rewrite it as such and
3109 -- analyze it to capture function calls that may require
3110 -- finalization actions.
3113 I_Spec
: constant Node_Id
:=
3114 Make_Iterator_Specification
(Sloc
(N
),
3115 Defining_Identifier
=> Relocate_Node
(Id
),
3117 Subtype_Indication
=> Empty
,
3118 Reverse_Present
=> Reverse_Present
(N
));
3119 Scheme
: constant Node_Id
:= Parent
(N
);
3122 Set_Iterator_Specification
(Scheme
, I_Spec
);
3123 Set_Loop_Parameter_Specification
(Scheme
, Empty
);
3124 Set_Iterator_Filter
(I_Spec
,
3125 Relocate_Node
(Iterator_Filter
(N
)));
3127 Analyze_Iterator_Specification
(I_Spec
);
3129 -- In a generic context, analyze the original domain of
3130 -- iteration, for name capture.
3132 if not Expander_Active
then
3136 -- Set kind of loop parameter, which may be used in the
3137 -- subsequent analysis of the condition in a quantified
3140 Mutate_Ekind
(Id
, E_Loop_Parameter
);
3144 -- Domain of iteration is not a function call, and is side-effect
3148 -- A quantified expression that appears in a pre/post condition
3149 -- is preanalyzed several times. If the range is given by an
3150 -- attribute reference it is rewritten as a range, and this is
3151 -- done even with expansion disabled. If the type is already set
3152 -- do not reanalyze, because a range with static bounds may be
3153 -- typed Integer by default.
3155 if Nkind
(Parent
(N
)) = N_Quantified_Expression
3156 and then Present
(Etype
(DS
))
3169 -- Some additional checks if we are iterating through a type
3171 if Is_Entity_Name
(DS
)
3172 and then Present
(Entity
(DS
))
3173 and then Is_Type
(Entity
(DS
))
3175 -- The subtype indication may denote the completion of an incomplete
3176 -- type declaration.
3178 if Ekind
(Entity
(DS
)) = E_Incomplete_Type
then
3179 Set_Entity
(DS
, Get_Full_View
(Entity
(DS
)));
3180 Set_Etype
(DS
, Entity
(DS
));
3183 Check_Predicate_Use
(Entity
(DS
));
3186 -- Error if not discrete type
3188 if not Is_Discrete_Type
(Etype
(DS
)) then
3189 Wrong_Type
(DS
, Any_Discrete
);
3190 Set_Etype
(DS
, Any_Type
);
3193 Check_Controlled_Array_Attribute
(DS
);
3195 if Nkind
(DS
) = N_Subtype_Indication
then
3196 Check_Predicate_Use
(Entity
(Subtype_Mark
(DS
)));
3199 if Nkind
(DS
) not in N_Raise_xxx_Error
then
3203 Mutate_Ekind
(Id
, E_Loop_Parameter
);
3204 Set_Is_Not_Self_Hidden
(Id
);
3206 -- A quantified expression which appears in a pre- or post-condition may
3207 -- be analyzed multiple times. The analysis of the range creates several
3208 -- itypes which reside in different scopes depending on whether the pre-
3209 -- or post-condition has been expanded. Update the type of the loop
3210 -- variable to reflect the proper itype at each stage of analysis.
3212 -- Loop_Nod might not be present when we are preanalyzing a class-wide
3213 -- pre/postcondition since preanalysis occurs in a place unrelated to
3214 -- the actual code and the quantified expression may be the outermost
3215 -- expression of the class-wide condition.
3218 or else Etype
(Id
) = Any_Type
3220 (Present
(Etype
(Id
))
3221 and then Is_Itype
(Etype
(Id
))
3222 and then Present
(Loop_Nod
)
3223 and then Nkind
(Parent
(Loop_Nod
)) = N_Expression_With_Actions
3224 and then Nkind
(Original_Node
(Parent
(Loop_Nod
))) =
3225 N_Quantified_Expression
)
3227 Set_Etype
(Id
, Etype
(DS
));
3230 -- Treat a range as an implicit reference to the type, to inhibit
3231 -- spurious warnings.
3233 Generate_Reference
(Base_Type
(Etype
(DS
)), N
, ' ');
3234 Set_Is_Known_Valid
(Id
, True);
3236 -- The loop is not a declarative part, so the loop variable must be
3237 -- frozen explicitly. Do not freeze while preanalyzing a quantified
3238 -- expression because the freeze node will not be inserted into the
3239 -- tree due to flag Is_Spec_Expression being set.
3241 if Nkind
(Parent
(N
)) /= N_Quantified_Expression
then
3243 Flist
: constant List_Id
:= Freeze_Entity
(Id
, N
);
3245 Insert_Actions
(N
, Flist
);
3249 -- Case where we have a range or a subtype, get type bounds
3251 if Nkind
(DS
) in N_Range | N_Subtype_Indication
3252 and then not Error_Posted
(DS
)
3253 and then Etype
(DS
) /= Any_Type
3254 and then Is_Discrete_Type
(Etype
(DS
))
3259 Null_Range
: Boolean := False;
3262 if Nkind
(DS
) = N_Range
then
3263 L
:= Low_Bound
(DS
);
3264 H
:= High_Bound
(DS
);
3267 Type_Low_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
3269 Type_High_Bound
(Underlying_Type
(Etype
(Subtype_Mark
(DS
))));
3272 -- Check for null or possibly null range and issue warning. We
3273 -- suppress such messages in generic templates and instances,
3274 -- because in practice they tend to be dubious in these cases. The
3275 -- check applies as well to rewritten array element loops where a
3276 -- null range may be detected statically.
3278 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> True) = GT
then
3279 if Compile_Time_Compare
(L
, H
, Assume_Valid
=> False) = GT
then
3280 -- Since we know the range of the loop is always null,
3281 -- set the appropriate flag to remove the loop entirely
3282 -- during expansion.
3284 Set_Is_Null_Loop
(Loop_Nod
);
3288 -- Suppress the warning if inside a generic template or
3289 -- instance, since in practice they tend to be dubious in these
3290 -- cases since they can result from intended parameterization.
3292 if not Inside_A_Generic
and then not In_Instance
then
3294 -- Specialize msg if invalid values could make the loop
3295 -- non-null after all.
3298 if Comes_From_Source
(N
) then
3300 ("??loop range is null, loop will not execute", DS
);
3303 -- Here is where the loop could execute because of
3304 -- invalid values, so issue appropriate message.
3306 elsif Comes_From_Source
(N
) then
3308 ("??loop range may be null, loop may not execute",
3311 ("??can only execute if invalid values are present",
3316 -- In either case, suppress warnings in the body of the loop,
3317 -- since it is likely that these warnings will be inappropriate
3318 -- if the loop never actually executes, which is likely.
3320 Set_Suppress_Loop_Warnings
(Loop_Nod
);
3322 -- The other case for a warning is a reverse loop where the
3323 -- upper bound is the integer literal zero or one, and the
3324 -- lower bound may exceed this value.
3326 -- For example, we have
3328 -- for J in reverse N .. 1 loop
3330 -- In practice, this is very likely to be a case of reversing
3331 -- the bounds incorrectly in the range.
3333 elsif Reverse_Present
(N
)
3334 and then Nkind
(Original_Node
(H
)) = N_Integer_Literal
3336 (Intval
(Original_Node
(H
)) = Uint_0
3338 Intval
(Original_Node
(H
)) = Uint_1
)
3340 -- Lower bound may in fact be known and known not to exceed
3341 -- upper bound (e.g. reverse 0 .. 1) and that's OK.
3343 if Compile_Time_Known_Value
(L
)
3344 and then Expr_Value
(L
) <= Expr_Value
(H
)
3348 -- Otherwise warning is warranted
3351 Error_Msg_N
("??loop range may be null", DS
);
3352 Error_Msg_N
("\??bounds may be wrong way round", DS
);
3356 -- Check if either bound is known to be outside the range of the
3357 -- loop parameter type, this is e.g. the case of a loop from
3358 -- 20..X where the type is 1..19.
3360 -- Such a loop is dubious since either it raises CE or it executes
3361 -- zero times, and that cannot be useful!
3363 if Etype
(DS
) /= Any_Type
3364 and then not Error_Posted
(DS
)
3365 and then Nkind
(DS
) = N_Subtype_Indication
3366 and then Nkind
(Constraint
(DS
)) = N_Range_Constraint
3369 LLo
: constant Node_Id
:=
3370 Low_Bound
(Range_Expression
(Constraint
(DS
)));
3371 LHi
: constant Node_Id
:=
3372 High_Bound
(Range_Expression
(Constraint
(DS
)));
3374 Bad_Bound
: Node_Id
:= Empty
;
3375 -- Suspicious loop bound
3378 -- At this stage L, H are the bounds of the type, and LLo
3379 -- Lhi are the low bound and high bound of the loop.
3381 if Compile_Time_Compare
(LLo
, L
, Assume_Valid
=> True) = LT
3383 Compile_Time_Compare
(LLo
, H
, Assume_Valid
=> True) = GT
3388 if Compile_Time_Compare
(LHi
, L
, Assume_Valid
=> True) = LT
3390 Compile_Time_Compare
(LHi
, H
, Assume_Valid
=> True) = GT
3395 if Present
(Bad_Bound
) then
3397 ("suspicious loop bound out of range of "
3398 & "loop subtype??", Bad_Bound
);
3400 ("\loop executes zero times or raises "
3401 & "Constraint_Error??", Bad_Bound
);
3404 if Compile_Time_Compare
(LLo
, LHi
, Assume_Valid
=> False)
3407 Error_Msg_N
("??constrained range is null",
3410 -- Additional constraints on modular types can be
3411 -- confusing, add more information.
3413 if Ekind
(Etype
(DS
)) = E_Modular_Integer_Subtype
then
3414 Error_Msg_Uint_1
:= Intval
(LLo
);
3415 Error_Msg_Uint_2
:= Intval
(LHi
);
3416 Error_Msg_NE
("\iterator has modular type &, " &
3417 "so the loop has bounds ^ ..^",
3422 Set_Is_Null_Loop
(Loop_Nod
);
3425 -- Suppress other warnings about the body of the loop, as
3426 -- it will never execute.
3427 Set_Suppress_Loop_Warnings
(Loop_Nod
);
3432 -- This declare block is about warnings, if we get an exception while
3433 -- testing for warnings, we simply abandon the attempt silently. This
3434 -- most likely occurs as the result of a previous error, but might
3435 -- just be an obscure case we have missed. In either case, not giving
3436 -- the warning is perfectly acceptable.
3440 -- With debug flag K we will get an exception unless an error
3441 -- has already occurred (useful for debugging).
3443 if Debug_Flag_K
then
3444 Check_Error_Detected
;
3449 -- Preanalyze the filter. Expansion will take place when enclosing
3450 -- loop is expanded.
3452 if Present
(Iterator_Filter
(N
)) then
3453 Preanalyze_And_Resolve
(Iterator_Filter
(N
), Standard_Boolean
);
3455 end Analyze_Loop_Parameter_Specification
;
3457 ----------------------------
3458 -- Analyze_Loop_Statement --
3459 ----------------------------
3461 procedure Analyze_Loop_Statement
(N
: Node_Id
) is
3463 -- The following exception is raised by routine Prepare_Loop_Statement
3464 -- to avoid further analysis of a transformed loop.
3466 procedure Prepare_Loop_Statement
3468 Stop_Processing
: out Boolean);
3469 -- Determine whether loop statement N with iteration scheme Iter must be
3470 -- transformed prior to analysis, and if so, perform it.
3471 -- If Stop_Processing is set to True, should stop further processing.
3473 ----------------------------
3474 -- Prepare_Loop_Statement --
3475 ----------------------------
3477 procedure Prepare_Loop_Statement
3479 Stop_Processing
: out Boolean)
3481 function Has_Sec_Stack_Default_Iterator
3482 (Cont_Typ
: Entity_Id
) return Boolean;
3483 pragma Inline
(Has_Sec_Stack_Default_Iterator
);
3484 -- Determine whether container type Cont_Typ has a default iterator
3485 -- that requires secondary stack management.
3487 function Is_Sec_Stack_Iteration_Primitive
3488 (Cont_Typ
: Entity_Id
;
3489 Iter_Prim_Nam
: Name_Id
) return Boolean;
3490 pragma Inline
(Is_Sec_Stack_Iteration_Primitive
);
3491 -- Determine whether container type Cont_Typ has an iteration routine
3492 -- described by its name Iter_Prim_Nam that requires secondary stack
3495 function Is_Wrapped_In_Block
(Stmt
: Node_Id
) return Boolean;
3496 pragma Inline
(Is_Wrapped_In_Block
);
3497 -- Determine whether arbitrary statement Stmt is the sole statement
3498 -- wrapped within some block, excluding pragmas.
3500 procedure Prepare_Iterator_Loop
3501 (Iter_Spec
: Node_Id
;
3502 Stop_Processing
: out Boolean);
3503 pragma Inline
(Prepare_Iterator_Loop
);
3504 -- Prepare an iterator loop with iteration specification Iter_Spec
3505 -- for transformation if needed.
3506 -- If Stop_Processing is set to True, should stop further processing.
3508 procedure Prepare_Param_Spec_Loop
3509 (Param_Spec
: Node_Id
;
3510 Stop_Processing
: out Boolean);
3511 pragma Inline
(Prepare_Param_Spec_Loop
);
3512 -- Prepare a discrete loop with parameter specification Param_Spec
3513 -- for transformation if needed.
3514 -- If Stop_Processing is set to True, should stop further processing.
3516 procedure Wrap_Loop_Statement
(Manage_Sec_Stack
: Boolean);
3517 pragma Inline
(Wrap_Loop_Statement
);
3518 -- Wrap loop statement N within a block. Flag Manage_Sec_Stack must
3519 -- be set when the block must mark and release the secondary stack.
3520 -- Should stop further processing after calling this procedure.
3522 ------------------------------------
3523 -- Has_Sec_Stack_Default_Iterator --
3524 ------------------------------------
3526 function Has_Sec_Stack_Default_Iterator
3527 (Cont_Typ
: Entity_Id
) return Boolean
3529 Def_Iter
: constant Node_Id
:=
3530 Find_Value_Of_Aspect
3531 (Cont_Typ
, Aspect_Default_Iterator
);
3535 and then Present
(Etype
(Def_Iter
))
3536 and then Requires_Transient_Scope
(Etype
(Def_Iter
));
3537 end Has_Sec_Stack_Default_Iterator
;
3539 --------------------------------------
3540 -- Is_Sec_Stack_Iteration_Primitive --
3541 --------------------------------------
3543 function Is_Sec_Stack_Iteration_Primitive
3544 (Cont_Typ
: Entity_Id
;
3545 Iter_Prim_Nam
: Name_Id
) return Boolean
3547 Iter_Prim
: constant Entity_Id
:=
3548 Get_Iterable_Type_Primitive
3549 (Cont_Typ
, Iter_Prim_Nam
);
3553 and then Requires_Transient_Scope
(Etype
(Iter_Prim
));
3554 end Is_Sec_Stack_Iteration_Primitive
;
3556 -------------------------
3557 -- Is_Wrapped_In_Block --
3558 -------------------------
3560 function Is_Wrapped_In_Block
(Stmt
: Node_Id
) return Boolean is
3566 Blk_Id
:= Current_Scope
;
3568 -- The current context is a block. Inspect the statements of the
3569 -- block to determine whether it wraps Stmt.
3571 if Ekind
(Blk_Id
) = E_Block
3572 and then Present
(Block_Node
(Blk_Id
))
3575 Handled_Statement_Sequence
(Parent
(Block_Node
(Blk_Id
)));
3577 -- Skip leading pragmas introduced for invariant and predicate
3580 Blk_Stmt
:= First
(Statements
(Blk_HSS
));
3581 while Present
(Blk_Stmt
)
3582 and then Nkind
(Blk_Stmt
) = N_Pragma
3587 return Blk_Stmt
= Stmt
and then No
(Next
(Blk_Stmt
));
3591 end Is_Wrapped_In_Block
;
3593 ---------------------------
3594 -- Prepare_Iterator_Loop --
3595 ---------------------------
3597 procedure Prepare_Iterator_Loop
3598 (Iter_Spec
: Node_Id
;
3599 Stop_Processing
: out Boolean)
3601 Cont_Typ
: Entity_Id
;
3606 Stop_Processing
:= False;
3608 -- The iterator specification has syntactic errors. Transform the
3609 -- loop into an infinite loop in order to safely perform at least
3610 -- some minor analysis. This check must come first.
3612 if Error_Posted
(Iter_Spec
) then
3613 Set_Iteration_Scheme
(N
, Empty
);
3615 Stop_Processing
:= True;
3617 -- Nothing to do when the loop is already wrapped in a block
3619 elsif Is_Wrapped_In_Block
(N
) then
3622 -- Otherwise the iterator loop traverses an array or a container
3623 -- and appears in the form
3625 -- for Def_Id in [reverse] Iterator_Name loop
3626 -- for Def_Id [: Subtyp_Indic] of [reverse] Iterable_Name loop
3629 -- Prepare a copy of the iterated name for preanalysis. The
3630 -- copy is semi inserted into the tree by setting its Parent
3633 Nam
:= Name
(Iter_Spec
);
3634 Nam_Copy
:= New_Copy_Tree
(Nam
);
3635 Set_Parent
(Nam_Copy
, Parent
(Nam
));
3637 -- Determine what the loop is iterating on
3639 Preanalyze_Range
(Nam_Copy
);
3640 Cont_Typ
:= Etype
(Nam_Copy
);
3642 -- The iterator loop is traversing an array. This case does not
3643 -- require any transformation, unless the name contains a call
3644 -- that returns on the secondary stack since we need to release
3645 -- the space allocated there.
3647 if Is_Array_Type
(Cont_Typ
)
3648 and then not Has_Sec_Stack_Call
(Nam_Copy
)
3652 -- Otherwise unconditionally wrap the loop statement within
3653 -- a block. The expansion of iterator loops may relocate the
3654 -- iterator outside the loop, thus "leaking" its entity into
3655 -- the enclosing scope. Wrapping the loop statement allows
3656 -- for multiple iterator loops using the same iterator name
3657 -- to coexist within the same scope.
3659 -- The block must manage the secondary stack when the iterator
3660 -- loop is traversing a container using either
3662 -- * A default iterator obtained on the secondary stack
3664 -- * Call to Iterate where the iterator is returned on the
3667 -- * Combination of First, Next, and Has_Element where the
3668 -- first two return a cursor on the secondary stack.
3672 (Manage_Sec_Stack
=>
3673 Has_Sec_Stack_Default_Iterator
(Cont_Typ
)
3674 or else Has_Sec_Stack_Call
(Nam_Copy
)
3675 or else Is_Sec_Stack_Iteration_Primitive
3676 (Cont_Typ
, Name_First
)
3677 or else Is_Sec_Stack_Iteration_Primitive
3678 (Cont_Typ
, Name_Next
));
3679 Stop_Processing
:= True;
3682 end Prepare_Iterator_Loop
;
3684 -----------------------------
3685 -- Prepare_Param_Spec_Loop --
3686 -----------------------------
3688 procedure Prepare_Param_Spec_Loop
3689 (Param_Spec
: Node_Id
;
3690 Stop_Processing
: out Boolean)
3696 Rng_Typ
: Entity_Id
;
3699 Stop_Processing
:= False;
3700 Rng
:= Discrete_Subtype_Definition
(Param_Spec
);
3702 -- Nothing to do when the loop is already wrapped in a block
3704 if Is_Wrapped_In_Block
(N
) then
3707 -- The parameter specification appears in the form
3709 -- for Def_Id in Subtype_Mark Constraint loop
3711 elsif Nkind
(Rng
) = N_Subtype_Indication
3712 and then Nkind
(Range_Expression
(Constraint
(Rng
))) = N_Range
3714 Rng
:= Range_Expression
(Constraint
(Rng
));
3716 -- Preanalyze the bounds of the range constraint, setting
3717 -- parent fields to associate the copied bounds with the range,
3718 -- allowing proper tree climbing during preanalysis.
3720 Low
:= New_Copy_Tree
(Low_Bound
(Rng
));
3721 High
:= New_Copy_Tree
(High_Bound
(Rng
));
3723 Set_Parent
(Low
, Rng
);
3724 Set_Parent
(High
, Rng
);
3729 -- The bounds contain at least one function call that returns
3730 -- on the secondary stack. Note that the loop must be wrapped
3731 -- only when such a call exists.
3733 if Has_Sec_Stack_Call
(Low
) or else Has_Sec_Stack_Call
(High
)
3735 Wrap_Loop_Statement
(Manage_Sec_Stack
=> True);
3736 Stop_Processing
:= True;
3739 -- Otherwise the parameter specification appears in the form
3741 -- for Def_Id in Range loop
3744 -- Prepare a copy of the discrete range for preanalysis. The
3745 -- copy is semi inserted into the tree by setting its Parent
3748 Rng_Copy
:= New_Copy_Tree
(Rng
);
3749 Set_Parent
(Rng_Copy
, Parent
(Rng
));
3751 -- Determine what the loop is iterating on
3753 Preanalyze_Range
(Rng_Copy
);
3754 Rng_Typ
:= Etype
(Rng_Copy
);
3756 -- Wrap the loop statement within a block in order to manage
3757 -- the secondary stack when the discrete range is
3759 -- * Either a Forward_Iterator or a Reverse_Iterator
3761 -- * Function call whose return type requires finalization
3764 -- ??? it is unclear why using Has_Sec_Stack_Call directly on
3765 -- the discrete range causes the freeze node of an itype to be
3766 -- in the wrong scope in complex assertion expressions.
3768 if Is_Iterator
(Rng_Typ
)
3769 or else (Nkind
(Rng_Copy
) = N_Function_Call
3770 and then Needs_Finalization
(Rng_Typ
))
3772 Wrap_Loop_Statement
(Manage_Sec_Stack
=> True);
3773 Stop_Processing
:= True;
3776 end Prepare_Param_Spec_Loop
;
3778 -------------------------
3779 -- Wrap_Loop_Statement --
3780 -------------------------
3782 procedure Wrap_Loop_Statement
(Manage_Sec_Stack
: Boolean) is
3783 Loc
: constant Source_Ptr
:= Sloc
(N
);
3790 Make_Block_Statement
(Loc
,
3791 Declarations
=> New_List
,
3792 Handled_Statement_Sequence
=>
3793 Make_Handled_Sequence_Of_Statements
(Loc
,
3794 Statements
=> New_List
(Relocate_Node
(N
))));
3796 Add_Block_Identifier
(Blk
, Blk_Id
);
3797 Set_Uses_Sec_Stack
(Blk_Id
, Manage_Sec_Stack
);
3801 end Wrap_Loop_Statement
;
3805 Iter_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
3806 Param_Spec
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3808 -- Start of processing for Prepare_Loop_Statement
3811 Stop_Processing
:= False;
3813 if Present
(Iter_Spec
) then
3814 Prepare_Iterator_Loop
(Iter_Spec
, Stop_Processing
);
3816 elsif Present
(Param_Spec
) then
3817 Prepare_Param_Spec_Loop
(Param_Spec
, Stop_Processing
);
3819 end Prepare_Loop_Statement
;
3821 -- Local declarations
3823 Id
: constant Node_Id
:= Identifier
(N
);
3824 Iter
: constant Node_Id
:= Iteration_Scheme
(N
);
3825 Loc
: constant Source_Ptr
:= Sloc
(N
);
3829 -- Start of processing for Analyze_Loop_Statement
3832 if Present
(Id
) then
3834 -- Make name visible, e.g. for use in exit statements. Loop labels
3835 -- are always considered to be referenced.
3840 -- Guard against serious error (typically, a scope mismatch when
3841 -- semantic analysis is requested) by creating loop entity to
3842 -- continue analysis.
3845 if Total_Errors_Detected
/= 0 then
3846 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3848 raise Program_Error
;
3851 -- Verify that the loop name is hot hidden by an unrelated
3852 -- declaration in an inner scope.
3854 elsif Ekind
(Ent
) /= E_Label
and then Ekind
(Ent
) /= E_Loop
then
3855 Error_Msg_Sloc
:= Sloc
(Ent
);
3856 Error_Msg_N
("implicit label declaration for & is hidden#", Id
);
3858 if Present
(Homonym
(Ent
))
3859 and then Ekind
(Homonym
(Ent
)) = E_Label
3861 Set_Entity
(Id
, Ent
);
3862 Mutate_Ekind
(Ent
, E_Loop
);
3866 Generate_Reference
(Ent
, N
, ' ');
3867 Generate_Definition
(Ent
);
3869 -- If we found a label, mark its type. If not, ignore it, since it
3870 -- means we have a conflicting declaration, which would already
3871 -- have been diagnosed at declaration time. Set Label_Construct
3872 -- of the implicit label declaration, which is not created by the
3873 -- parser for generic units.
3875 if Ekind
(Ent
) = E_Label
then
3876 Reinit_Field_To_Zero
(Ent
, F_Enclosing_Scope
);
3877 Reinit_Field_To_Zero
(Ent
, F_Reachable
);
3878 Mutate_Ekind
(Ent
, E_Loop
);
3880 if Nkind
(Parent
(Ent
)) = N_Implicit_Label_Declaration
then
3881 Set_Label_Construct
(Parent
(Ent
), N
);
3886 -- Case of no identifier present. Create one and attach it to the
3887 -- loop statement for use as a scope and as a reference for later
3888 -- expansions. Indicate that the label does not come from source,
3889 -- and attach it to the loop statement so it is part of the tree,
3890 -- even without a full declaration.
3893 Ent
:= New_Internal_Entity
(E_Loop
, Current_Scope
, Loc
, 'L');
3894 Set_Etype
(Ent
, Standard_Void_Type
);
3895 Set_Identifier
(N
, New_Occurrence_Of
(Ent
, Loc
));
3896 Set_Parent
(Ent
, N
);
3897 Set_Has_Created_Identifier
(N
);
3900 -- Determine whether the loop statement must be transformed prior to
3901 -- analysis, and if so, perform it. This early modification is needed
3904 -- * The loop has an erroneous iteration scheme. In this case the
3905 -- loop is converted into an infinite loop in order to perform
3908 -- * The loop is an Ada 2012 iterator loop. In this case the loop is
3909 -- wrapped within a block to provide a local scope for the iterator.
3910 -- If the iterator specification requires the secondary stack in any
3911 -- way, the block is marked in order to manage it.
3913 -- * The loop is using a parameter specification where the discrete
3914 -- range requires the secondary stack. In this case the loop is
3915 -- wrapped within a block in order to manage the secondary stack.
3917 -- ??? This overlooks finalization: the loop may leave the secondary
3918 -- stack untouched, but its iterator or discrete range may need
3919 -- finalization, in which case the block is also required. Therefore
3920 -- the criterion must be based on Sem_Util.Requires_Transient_Scope,
3921 -- which happens to be what is currently implemented.
3923 if Present
(Iter
) then
3925 Stop_Processing
: Boolean;
3927 Prepare_Loop_Statement
(Iter
, Stop_Processing
);
3929 if Stop_Processing
then
3935 -- Kill current values on entry to loop, since statements in the body of
3936 -- the loop may have been executed before the loop is entered. Similarly
3937 -- we kill values after the loop, since we do not know that the body of
3938 -- the loop was executed.
3940 Kill_Current_Values
;
3942 Analyze_Iteration_Scheme
(Iter
);
3944 -- Check for following case which merits a warning if the type E of is
3945 -- a multi-dimensional array (and no explicit subscript ranges present).
3951 and then Present
(Loop_Parameter_Specification
(Iter
))
3954 LPS
: constant Node_Id
:= Loop_Parameter_Specification
(Iter
);
3955 DSD
: constant Node_Id
:=
3956 Original_Node
(Discrete_Subtype_Definition
(LPS
));
3958 if Nkind
(DSD
) = N_Attribute_Reference
3959 and then Attribute_Name
(DSD
) = Name_Range
3960 and then No
(Expressions
(DSD
))
3963 Typ
: constant Entity_Id
:= Etype
(Prefix
(DSD
));
3965 if Is_Array_Type
(Typ
)
3966 and then Number_Dimensions
(Typ
) > 1
3967 and then Nkind
(Parent
(N
)) = N_Loop_Statement
3968 and then Present
(Iteration_Scheme
(Parent
(N
)))
3971 OIter
: constant Node_Id
:=
3972 Iteration_Scheme
(Parent
(N
));
3973 OLPS
: constant Node_Id
:=
3974 Loop_Parameter_Specification
(OIter
);
3975 ODSD
: constant Node_Id
:=
3976 Original_Node
(Discrete_Subtype_Definition
(OLPS
));
3978 if Nkind
(ODSD
) = N_Attribute_Reference
3979 and then Attribute_Name
(ODSD
) = Name_Range
3980 and then No
(Expressions
(ODSD
))
3981 and then Etype
(Prefix
(ODSD
)) = Typ
3983 Error_Msg_Sloc
:= Sloc
(ODSD
);
3985 ("inner range same as outer range#??", DSD
);
3994 -- Analyze the statements of the body except in the case of an Ada 2012
3995 -- iterator with the expander active. In this case the expander will do
3996 -- a rewrite of the loop into a while loop. We will then analyze the
3997 -- loop body when we analyze this while loop.
3999 -- We need to do this delay because if the container is for indefinite
4000 -- types the actual subtype of the components will only be determined
4001 -- when the cursor declaration is analyzed.
4003 -- If the expander is not active then we want to analyze the loop body
4004 -- now even in the Ada 2012 iterator case, since the rewriting will not
4005 -- be done. Insert the loop variable in the current scope, if not done
4006 -- when analysing the iteration scheme. Set its kind properly to detect
4007 -- improper uses in the loop body.
4009 -- In GNATprove mode, we do one of the above depending on the kind of
4010 -- loop. If it is an iterator over an array, then we do not analyze the
4011 -- loop now. We will analyze it after it has been rewritten by the
4012 -- special SPARK expansion which is activated in GNATprove mode. We need
4013 -- to do this so that other expansions that should occur in GNATprove
4014 -- mode take into account the specificities of the rewritten loop, in
4015 -- particular the introduction of a renaming (which needs to be
4018 -- In other cases in GNATprove mode then we want to analyze the loop
4019 -- body now, since no rewriting will occur. Within a generic the
4020 -- GNATprove mode is irrelevant, we must analyze the generic for
4021 -- non-local name capture.
4024 and then Present
(Iterator_Specification
(Iter
))
4027 and then Is_Iterator_Over_Array
(Iterator_Specification
(Iter
))
4028 and then not Inside_A_Generic
4032 elsif not Expander_Active
then
4034 I_Spec
: constant Node_Id
:= Iterator_Specification
(Iter
);
4035 Id
: constant Entity_Id
:= Defining_Identifier
(I_Spec
);
4038 if Scope
(Id
) /= Current_Scope
then
4042 -- In an element iterator, the loop parameter is a variable if
4043 -- the domain of iteration (container or array) is a variable.
4045 if not Of_Present
(I_Spec
)
4046 or else not Is_Variable
(Name
(I_Spec
))
4048 Mutate_Ekind
(Id
, E_Loop_Parameter
);
4052 Analyze_Statements
(Statements
(N
));
4056 -- Pre-Ada2012 for-loops and while loops
4058 Analyze_Statements
(Statements
(N
));
4061 -- If the loop has no side effects, mark it for removal.
4063 if Side_Effect_Free_Loop
(N
) then
4064 Set_Is_Null_Loop
(N
);
4067 -- When the iteration scheme of a loop contains attribute 'Loop_Entry,
4068 -- the loop is transformed into a conditional block. Retrieve the loop.
4072 if Subject_To_Loop_Entry_Attributes
(Stmt
) then
4073 Stmt
:= Find_Loop_In_Conditional_Block
(Stmt
);
4076 -- Finish up processing for the loop. We kill all current values, since
4077 -- in general we don't know if the statements in the loop have been
4078 -- executed. We could do a bit better than this with a loop that we
4079 -- know will execute at least once, but it's not worth the trouble and
4080 -- the front end is not in the business of flow tracing.
4082 Process_End_Label
(Stmt
, 'e', Ent
);
4084 Kill_Current_Values
;
4086 -- Check for infinite loop. Skip check for generated code, since it
4087 -- justs waste time and makes debugging the routine called harder.
4089 -- Note that we have to wait till the body of the loop is fully analyzed
4090 -- before making this call, since Check_Infinite_Loop_Warning relies on
4091 -- being able to use semantic visibility information to find references.
4093 if Comes_From_Source
(Stmt
) then
4094 Check_Infinite_Loop_Warning
(Stmt
);
4097 -- Code after loop is unreachable if the loop has no WHILE or FOR and
4098 -- contains no EXIT statements within the body of the loop.
4100 if No
(Iter
) and then not Has_Exit
(Ent
) then
4101 Check_Unreachable_Code
(Stmt
);
4103 end Analyze_Loop_Statement
;
4105 ----------------------------
4106 -- Analyze_Null_Statement --
4107 ----------------------------
4109 -- Note: the semantics of the null statement is implemented by a single
4110 -- null statement, too bad everything isn't as simple as this.
4112 procedure Analyze_Null_Statement
(N
: Node_Id
) is
4113 pragma Warnings
(Off
, N
);
4116 end Analyze_Null_Statement
;
4118 -------------------------
4119 -- Analyze_Target_Name --
4120 -------------------------
4122 procedure Analyze_Target_Name
(N
: Node_Id
) is
4123 procedure Report_Error
;
4124 -- Complain about illegal use of target_name and rewrite it into unknown
4131 procedure Report_Error
is
4134 ("must appear in the right-hand side of an assignment statement",
4136 Rewrite
(N
, New_Occurrence_Of
(Any_Id
, Sloc
(N
)));
4139 -- Start of processing for Analyze_Target_Name
4142 -- A target name has the type of the left-hand side of the enclosing
4145 -- First, verify that the context is the right-hand side of an
4146 -- assignment statement.
4148 if No
(Current_Assignment
) then
4154 Current
: Node_Id
:= N
;
4155 Context
: Node_Id
:= Parent
(N
);
4157 while Present
(Context
) loop
4159 -- Check if target_name appears in the expression of the enclosing
4162 if Nkind
(Context
) = N_Assignment_Statement
then
4163 if Current
= Expression
(Context
) then
4164 pragma Assert
(Context
= Current_Assignment
);
4165 Set_Etype
(N
, Etype
(Name
(Current_Assignment
)));
4171 -- Prevent the search from going too far
4173 elsif Is_Body_Or_Package_Declaration
(Context
) then
4179 Context
:= Parent
(Context
);
4184 end Analyze_Target_Name
;
4186 ------------------------
4187 -- Analyze_Statements --
4188 ------------------------
4190 procedure Analyze_Statements
(L
: List_Id
) is
4195 -- The labels declared in the statement list are reachable from
4196 -- statements in the list. We do this as a prepass so that any goto
4197 -- statement will be properly flagged if its target is not reachable.
4198 -- This is not required, but is nice behavior.
4201 while Present
(S
) loop
4202 if Nkind
(S
) = N_Label
then
4203 Analyze
(Identifier
(S
));
4204 Lab
:= Entity
(Identifier
(S
));
4206 -- If we found a label mark it as reachable
4208 if Ekind
(Lab
) = E_Label
then
4209 Generate_Definition
(Lab
);
4210 Set_Reachable
(Lab
);
4212 if Nkind
(Parent
(Lab
)) = N_Implicit_Label_Declaration
then
4213 Set_Label_Construct
(Parent
(Lab
), S
);
4216 -- If we failed to find a label, it means the implicit declaration
4217 -- of the label was hidden. A for-loop parameter can do this to
4218 -- a label with the same name inside the loop, since the implicit
4219 -- label declaration is in the innermost enclosing body or block
4223 Error_Msg_Sloc
:= Sloc
(Lab
);
4225 ("implicit label declaration for & is hidden#",
4233 -- Perform semantic analysis on all statements
4235 Conditional_Statements_Begin
;
4238 while Present
(S
) loop
4241 -- Remove dimension in all statements
4243 Remove_Dimension_In_Statement
(S
);
4247 Conditional_Statements_End
;
4249 -- Make labels unreachable. Visibility is not sufficient, because labels
4250 -- in one if-branch for example are not reachable from the other branch,
4251 -- even though their declarations are in the enclosing declarative part.
4254 while Present
(S
) loop
4255 if Nkind
(S
) = N_Label
4256 and then Ekind
(Entity
(Identifier
(S
))) = E_Label
4258 Set_Reachable
(Entity
(Identifier
(S
)), False);
4263 end Analyze_Statements
;
4265 ----------------------------
4266 -- Check_Unreachable_Code --
4267 ----------------------------
4269 procedure Check_Unreachable_Code
(N
: Node_Id
) is
4271 function Is_Simple_Case
(N
: Node_Id
) return Boolean;
4272 -- N is the condition of an if statement. True if N is simple enough
4273 -- that we should not set Unblocked_Exit_Count in the special case
4276 --------------------
4277 -- Is_Simple_Case --
4278 --------------------
4280 function Is_Simple_Case
(N
: Node_Id
) return Boolean is
4283 Is_Trivial_Boolean
(N
)
4285 (Comes_From_Source
(N
)
4286 and then Is_Static_Expression
(N
)
4287 and then Nkind
(N
) in N_Identifier | N_Expanded_Name
4288 and then Ekind
(Entity
(N
)) = E_Constant
)
4291 and then Nkind
(Original_Node
(N
)) = N_Op_Not
4292 and then Is_Simple_Case
(Right_Opnd
(Original_Node
(N
))));
4295 Error_Node
: Node_Id
;
4300 if Comes_From_Source
(N
) then
4301 Nxt
:= Original_Node
(Next
(N
));
4303 -- Skip past pragmas
4305 while Nkind
(Nxt
) = N_Pragma
loop
4306 Nxt
:= Original_Node
(Next
(Nxt
));
4309 -- If a label follows us, then we never have dead code, since someone
4310 -- could branch to the label, so we just ignore it.
4312 if Nkind
(Nxt
) = N_Label
then
4315 -- Otherwise see if we have a real statement following us
4317 elsif Comes_From_Source
(Nxt
)
4318 and then Is_Statement
(Nxt
)
4320 -- Special very annoying exception. Ada RM 6.5(5) annoyingly
4321 -- requires functions to have at least one return statement, so
4322 -- don't complain about a simple return that follows a raise or a
4323 -- call to procedure with No_Return.
4325 if not (Present
(Current_Subprogram
)
4326 and then Ekind
(Current_Subprogram
) = E_Function
4327 and then (Nkind
(N
) in N_Raise_Statement
4329 (Nkind
(N
) = N_Procedure_Call_Statement
4330 and then Is_Entity_Name
(Name
(N
))
4331 and then Present
(Entity
(Name
(N
)))
4332 and then No_Return
(Entity
(Name
(N
)))))
4333 and then Nkind
(Nxt
) = N_Simple_Return_Statement
)
4335 -- The rather strange shenanigans with the warning message
4336 -- here reflects the fact that Kill_Dead_Code is very good at
4337 -- removing warnings in deleted code, and this is one warning
4338 -- we would prefer NOT to have removed.
4342 -- If we have unreachable code, analyze and remove the
4343 -- unreachable code, since it is useless and we don't want
4344 -- to generate junk warnings.
4346 -- We skip this step if we are not in code generation mode.
4348 -- This is the one case where we remove dead code in the
4349 -- semantics as opposed to the expander, and we do not want
4350 -- to remove code if we are not in code generation mode, since
4351 -- this messes up the tree or loses useful information for
4352 -- analysis tools such as CodePeer.
4354 -- Note that one might react by moving the whole circuit to
4355 -- exp_ch5, but then we lose the warning in -gnatc mode.
4357 if Operating_Mode
= Generate_Code
then
4360 Del
: constant Node_Id
:= Next
(N
);
4361 -- Node to be possibly deleted
4363 -- Quit deleting when we have nothing more to delete
4364 -- or if we hit a label (since someone could transfer
4365 -- control to a label, so we should not delete it).
4367 exit when No
(Del
) or else Nkind
(Del
) = N_Label
;
4369 -- Statement/declaration is to be deleted
4372 Kill_Dead_Code
(Del
);
4377 -- If this is a function, we add "raise Program_Error;",
4378 -- because otherwise, we will get incorrect warnings about
4379 -- falling off the end of the function.
4382 Subp
: constant Entity_Id
:= Current_Subprogram
;
4384 if Present
(Subp
) and then Ekind
(Subp
) = E_Function
then
4385 Insert_After_And_Analyze
(N
,
4386 Make_Raise_Program_Error
(Sloc
(Error_Node
),
4387 Reason
=> PE_Missing_Return
));
4393 -- Suppress the warning in instances, because a statement can
4394 -- be unreachable in some instances but not others.
4396 if not In_Instance
then
4397 Error_Msg_N
("??unreachable code!", Error_Node
);
4401 -- If the unconditional transfer of control instruction is the
4402 -- last statement of a sequence, then see if our parent is one of
4403 -- the constructs for which we count unblocked exits, and if so,
4404 -- adjust the count.
4409 -- Statements in THEN part or ELSE part of IF statement
4411 if Nkind
(P
) = N_If_Statement
then
4414 -- Statements in ELSIF part of an IF statement
4416 elsif Nkind
(P
) = N_Elsif_Part
then
4418 pragma Assert
(Nkind
(P
) = N_If_Statement
);
4420 -- Statements in CASE statement alternative
4422 elsif Nkind
(P
) = N_Case_Statement_Alternative
then
4424 pragma Assert
(Nkind
(P
) = N_Case_Statement
);
4426 -- Statements in body of block
4428 elsif Nkind
(P
) = N_Handled_Sequence_Of_Statements
4429 and then Nkind
(Parent
(P
)) = N_Block_Statement
4431 -- The original loop is now placed inside a block statement
4432 -- due to the expansion of attribute 'Loop_Entry. Return as
4433 -- this is not a "real" block for the purposes of exit
4436 if Nkind
(N
) = N_Loop_Statement
4437 and then Subject_To_Loop_Entry_Attributes
(N
)
4442 -- Statements in exception handler in a block
4444 elsif Nkind
(P
) = N_Exception_Handler
4445 and then Nkind
(Parent
(P
)) = N_Handled_Sequence_Of_Statements
4446 and then Nkind
(Parent
(Parent
(P
))) = N_Block_Statement
4450 -- None of these cases, so return
4456 -- This was one of the cases we are looking for (i.e. the parent
4457 -- construct was IF, CASE or block). In most cases, we simply
4458 -- decrement the count. However, if the parent is something like:
4461 -- raise ...; -- or some other jump
4464 -- where cond is an expression that is known-true at compile time,
4465 -- we can treat that as just the jump -- i.e. anything following
4466 -- the if statement is unreachable. We don't do this for simple
4467 -- cases like "if True" or "if Debug_Flag", because that causes
4468 -- too many warnings.
4470 if Nkind
(P
) = N_If_Statement
4471 and then Present
(Then_Statements
(P
))
4472 and then No
(Elsif_Parts
(P
))
4473 and then No
(Else_Statements
(P
))
4474 and then Is_OK_Static_Expression
(Condition
(P
))
4475 and then Is_True
(Expr_Value
(Condition
(P
)))
4476 and then not Is_Simple_Case
(Condition
(P
))
4478 pragma Assert
(Unblocked_Exit_Count
= 2);
4479 Unblocked_Exit_Count
:= 0;
4481 Unblocked_Exit_Count
:= Unblocked_Exit_Count
- 1;
4485 end Check_Unreachable_Code
;
4487 ------------------------
4488 -- Has_Sec_Stack_Call --
4489 ------------------------
4491 function Has_Sec_Stack_Call
(N
: Node_Id
) return Boolean is
4492 function Check_Call
(N
: Node_Id
) return Traverse_Result
;
4493 -- Check if N is a function call which uses the secondary stack
4499 function Check_Call
(N
: Node_Id
) return Traverse_Result
is
4505 if Nkind
(N
) = N_Function_Call
then
4508 -- Obtain the subprogram being invoked
4511 if Nkind
(Nam
) = N_Explicit_Dereference
then
4512 Nam
:= Prefix
(Nam
);
4514 elsif Nkind
(Nam
) = N_Selected_Component
then
4515 Nam
:= Selector_Name
(Nam
);
4522 Subp
:= Entity
(Nam
);
4524 if Present
(Subp
) then
4525 Typ
:= Etype
(Subp
);
4527 if Requires_Transient_Scope
(Typ
) then
4530 elsif Sec_Stack_Needed_For_Return
(Subp
) then
4536 -- Continue traversing the tree
4541 function Check_Calls
is new Traverse_Func
(Check_Call
);
4543 -- Start of processing for Has_Sec_Stack_Call
4546 return Check_Calls
(N
) = Abandon
;
4547 end Has_Sec_Stack_Call
;
4549 ----------------------
4550 -- Preanalyze_Range --
4551 ----------------------
4553 procedure Preanalyze_Range
(R_Copy
: Node_Id
) is
4554 Save_Analysis
: constant Boolean := Full_Analysis
;
4558 Full_Analysis
:= False;
4559 Expander_Mode_Save_And_Set
(False);
4561 -- In addition to the above we must explicitly suppress the generation
4562 -- of freeze nodes that might otherwise be generated during resolution
4563 -- of the range (e.g. if given by an attribute that will freeze its
4566 Set_Must_Not_Freeze
(R_Copy
);
4568 if Nkind
(R_Copy
) = N_Attribute_Reference
then
4569 Set_Must_Not_Freeze
(Prefix
(R_Copy
));
4574 if Nkind
(R_Copy
) in N_Subexpr
and then Is_Overloaded
(R_Copy
) then
4576 -- Apply preference rules for range of predefined integer types, or
4577 -- check for array or iterable construct for "of" iterator, or
4578 -- diagnose true ambiguity.
4583 Found
: Entity_Id
:= Empty
;
4586 Get_First_Interp
(R_Copy
, I
, It
);
4587 while Present
(It
.Typ
) loop
4588 if Is_Discrete_Type
(It
.Typ
) then
4592 if Scope
(Found
) = Standard_Standard
then
4595 elsif Scope
(It
.Typ
) = Standard_Standard
then
4599 -- Both of them are user-defined
4602 ("ambiguous bounds in range of iteration", R_Copy
);
4603 Error_Msg_N
("\possible interpretations:", R_Copy
);
4604 Error_Msg_NE
("\\}", R_Copy
, Found
);
4605 Error_Msg_NE
("\\}", R_Copy
, It
.Typ
);
4610 elsif Nkind
(Parent
(R_Copy
)) = N_Iterator_Specification
4611 and then Of_Present
(Parent
(R_Copy
))
4613 if Is_Array_Type
(It
.Typ
)
4614 or else Has_Aspect
(It
.Typ
, Aspect_Iterator_Element
)
4615 or else Has_Aspect
(It
.Typ
, Aspect_Constant_Indexing
)
4616 or else Has_Aspect
(It
.Typ
, Aspect_Variable_Indexing
)
4620 Set_Etype
(R_Copy
, It
.Typ
);
4623 Error_Msg_N
("ambiguous domain of iteration", R_Copy
);
4628 Get_Next_Interp
(I
, It
);
4633 -- Subtype mark in iteration scheme
4635 if Is_Entity_Name
(R_Copy
) and then Is_Type
(Entity
(R_Copy
)) then
4638 -- Expression in range, or Ada 2012 iterator
4640 elsif Nkind
(R_Copy
) in N_Subexpr
then
4642 Typ
:= Etype
(R_Copy
);
4644 if Is_Discrete_Type
(Typ
) then
4647 -- Check that the resulting object is an iterable container
4649 elsif Has_Aspect
(Typ
, Aspect_Iterator_Element
)
4650 or else Has_Aspect
(Typ
, Aspect_Constant_Indexing
)
4651 or else Has_Aspect
(Typ
, Aspect_Variable_Indexing
)
4655 -- The expression may yield an implicit reference to an iterable
4656 -- container. Insert explicit dereference so that proper type is
4657 -- visible in the loop.
4659 elsif Has_Implicit_Dereference
(Etype
(R_Copy
)) then
4660 Build_Explicit_Dereference
4661 (R_Copy
, Get_Reference_Discriminant
(Etype
(R_Copy
)));
4665 Expander_Mode_Restore
;
4666 Full_Analysis
:= Save_Analysis
;
4667 end Preanalyze_Range
;