1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2008, 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 Atree
; use Atree
;
27 with Debug
; use Debug
;
28 with Elists
; use Elists
;
29 with Einfo
; use Einfo
;
30 with Exp_Disp
; use Exp_Disp
;
31 with Exp_Ch7
; use Exp_Ch7
;
32 with Exp_Tss
; use Exp_Tss
;
33 with Errout
; use Errout
;
34 with Lib
.Xref
; use Lib
.Xref
;
35 with Namet
; use Namet
;
36 with Nlists
; use Nlists
;
37 with Nmake
; use Nmake
;
39 with Output
; use Output
;
40 with Restrict
; use Restrict
;
41 with Rident
; use Rident
;
43 with Sem_Ch6
; use Sem_Ch6
;
44 with Sem_Eval
; use Sem_Eval
;
45 with Sem_Type
; use Sem_Type
;
46 with Sem_Util
; use Sem_Util
;
47 with Snames
; use Snames
;
48 with Stand
; use Stand
;
49 with Sinfo
; use Sinfo
;
50 with Targparm
; use Targparm
;
51 with Tbuild
; use Tbuild
;
52 with Uintp
; use Uintp
;
54 package body Sem_Disp
is
56 -----------------------
57 -- Local Subprograms --
58 -----------------------
60 procedure Add_Dispatching_Operation
61 (Tagged_Type
: Entity_Id
;
63 -- Add New_Op in the list of primitive operations of Tagged_Type
65 function Check_Controlling_Type
67 Subp
: Entity_Id
) return Entity_Id
;
68 -- T is the tagged type of a formal parameter or the result of Subp.
69 -- If the subprogram has a controlling parameter or result that matches
70 -- the type, then returns the tagged type of that parameter or result
71 -- (returning the designated tagged type in the case of an access
72 -- parameter); otherwise returns empty.
74 -------------------------------
75 -- Add_Dispatching_Operation --
76 -------------------------------
78 procedure Add_Dispatching_Operation
79 (Tagged_Type
: Entity_Id
;
82 List
: constant Elist_Id
:= Primitive_Operations
(Tagged_Type
);
85 -- The dispatching operation may already be on the list, if it the
86 -- wrapper for an inherited function of a null extension (see exp_ch3
87 -- for the construction of function wrappers). The list of primitive
88 -- operations must not contain duplicates.
90 Append_Unique_Elmt
(New_Op
, List
);
91 end Add_Dispatching_Operation
;
93 -------------------------------
94 -- Check_Controlling_Formals --
95 -------------------------------
97 procedure Check_Controlling_Formals
102 Ctrl_Type
: Entity_Id
;
105 Formal
:= First_Formal
(Subp
);
107 while Present
(Formal
) loop
108 Ctrl_Type
:= Check_Controlling_Type
(Etype
(Formal
), Subp
);
110 if Present
(Ctrl_Type
) then
112 -- When the controlling type is concurrent and declared within a
113 -- generic or inside an instance, use its corresponding record
116 if Is_Concurrent_Type
(Ctrl_Type
)
117 and then Present
(Corresponding_Record_Type
(Ctrl_Type
))
119 Ctrl_Type
:= Corresponding_Record_Type
(Ctrl_Type
);
122 if Ctrl_Type
= Typ
then
123 Set_Is_Controlling_Formal
(Formal
);
125 -- Ada 2005 (AI-231): Anonymous access types used in
126 -- controlling parameters exclude null because it is necessary
127 -- to read the tag to dispatch, and null has no tag.
129 if Ekind
(Etype
(Formal
)) = E_Anonymous_Access_Type
then
130 Set_Can_Never_Be_Null
(Etype
(Formal
));
131 Set_Is_Known_Non_Null
(Etype
(Formal
));
134 -- Check that the parameter's nominal subtype statically
135 -- matches the first subtype.
137 if Ekind
(Etype
(Formal
)) = E_Anonymous_Access_Type
then
138 if not Subtypes_Statically_Match
139 (Typ
, Designated_Type
(Etype
(Formal
)))
142 ("parameter subtype does not match controlling type",
146 elsif not Subtypes_Statically_Match
(Typ
, Etype
(Formal
)) then
148 ("parameter subtype does not match controlling type",
152 if Present
(Default_Value
(Formal
)) then
154 -- In Ada 2005, access parameters can have defaults
156 if Ekind
(Etype
(Formal
)) = E_Anonymous_Access_Type
157 and then Ada_Version
< Ada_05
160 ("default not allowed for controlling access parameter",
161 Default_Value
(Formal
));
163 elsif not Is_Tag_Indeterminate
(Default_Value
(Formal
)) then
165 ("default expression must be a tag indeterminate" &
166 " function call", Default_Value
(Formal
));
170 elsif Comes_From_Source
(Subp
) then
172 ("operation can be dispatching in only one type", Subp
);
176 Next_Formal
(Formal
);
179 if Present
(Etype
(Subp
)) then
180 Ctrl_Type
:= Check_Controlling_Type
(Etype
(Subp
), Subp
);
182 if Present
(Ctrl_Type
) then
183 if Ctrl_Type
= Typ
then
184 Set_Has_Controlling_Result
(Subp
);
186 -- Check that result subtype statically matches first subtype
187 -- (Ada 2005) : Subp may have a controlling access result.
189 if Subtypes_Statically_Match
(Typ
, Etype
(Subp
))
190 or else (Ekind
(Etype
(Subp
)) = E_Anonymous_Access_Type
192 Subtypes_Statically_Match
193 (Typ
, Designated_Type
(Etype
(Subp
))))
199 ("result subtype does not match controlling type", Subp
);
202 elsif Comes_From_Source
(Subp
) then
204 ("operation can be dispatching in only one type", Subp
);
208 end Check_Controlling_Formals
;
210 ----------------------------
211 -- Check_Controlling_Type --
212 ----------------------------
214 function Check_Controlling_Type
216 Subp
: Entity_Id
) return Entity_Id
218 Tagged_Type
: Entity_Id
:= Empty
;
221 if Is_Tagged_Type
(T
) then
222 if Is_First_Subtype
(T
) then
225 Tagged_Type
:= Base_Type
(T
);
228 elsif Ekind
(T
) = E_Anonymous_Access_Type
229 and then Is_Tagged_Type
(Designated_Type
(T
))
231 if Ekind
(Designated_Type
(T
)) /= E_Incomplete_Type
then
232 if Is_First_Subtype
(Designated_Type
(T
)) then
233 Tagged_Type
:= Designated_Type
(T
);
235 Tagged_Type
:= Base_Type
(Designated_Type
(T
));
238 -- Ada 2005 : an incomplete type can be tagged. An operation with
239 -- an access parameter of the type is dispatching.
241 elsif Scope
(Designated_Type
(T
)) = Current_Scope
then
242 Tagged_Type
:= Designated_Type
(T
);
244 -- Ada 2005 (AI-50217)
246 elsif From_With_Type
(Designated_Type
(T
))
247 and then Present
(Non_Limited_View
(Designated_Type
(T
)))
249 if Is_First_Subtype
(Non_Limited_View
(Designated_Type
(T
))) then
250 Tagged_Type
:= Non_Limited_View
(Designated_Type
(T
));
252 Tagged_Type
:= Base_Type
(Non_Limited_View
253 (Designated_Type
(T
)));
259 or else Is_Class_Wide_Type
(Tagged_Type
)
263 -- The dispatching type and the primitive operation must be defined
264 -- in the same scope, except in the case of internal operations and
265 -- formal abstract subprograms.
267 elsif ((Scope
(Subp
) = Scope
(Tagged_Type
) or else Is_Internal
(Subp
))
268 and then (not Is_Generic_Type
(Tagged_Type
)
269 or else not Comes_From_Source
(Subp
)))
271 (Is_Formal_Subprogram
(Subp
) and then Is_Abstract_Subprogram
(Subp
))
273 (Nkind
(Parent
(Parent
(Subp
))) = N_Subprogram_Renaming_Declaration
275 Present
(Corresponding_Formal_Spec
(Parent
(Parent
(Subp
))))
277 Is_Abstract_Subprogram
(Subp
))
284 end Check_Controlling_Type
;
286 ----------------------------
287 -- Check_Dispatching_Call --
288 ----------------------------
290 procedure Check_Dispatching_Call
(N
: Node_Id
) is
291 Loc
: constant Source_Ptr
:= Sloc
(N
);
294 Control
: Node_Id
:= Empty
;
296 Subp_Entity
: Entity_Id
;
297 Indeterm_Ancestor_Call
: Boolean := False;
298 Indeterm_Ctrl_Type
: Entity_Id
;
300 Static_Tag
: Node_Id
:= Empty
;
301 -- If a controlling formal has a statically tagged actual, the tag of
302 -- this actual is to be used for any tag-indeterminate actual
304 procedure Check_Dispatching_Context
;
305 -- If the call is tag-indeterminate and the entity being called is
306 -- abstract, verify that the context is a call that will eventually
307 -- provide a tag for dispatching, or has provided one already.
309 -------------------------------
310 -- Check_Dispatching_Context --
311 -------------------------------
313 procedure Check_Dispatching_Context
is
314 Subp
: constant Entity_Id
:= Entity
(Name
(N
));
318 if Is_Abstract_Subprogram
(Subp
)
319 and then No
(Controlling_Argument
(N
))
321 if Present
(Alias
(Subp
))
322 and then not Is_Abstract_Subprogram
(Alias
(Subp
))
323 and then No
(DTC_Entity
(Subp
))
325 -- Private overriding of inherited abstract operation,
328 Set_Entity
(Name
(N
), Alias
(Subp
));
334 while Present
(Par
) loop
336 if (Nkind
(Par
) = N_Function_Call
or else
337 Nkind
(Par
) = N_Procedure_Call_Statement
or else
338 Nkind
(Par
) = N_Assignment_Statement
or else
339 Nkind
(Par
) = N_Op_Eq
or else
340 Nkind
(Par
) = N_Op_Ne
)
341 and then Is_Tagged_Type
(Etype
(Subp
))
345 elsif Nkind
(Par
) = N_Qualified_Expression
346 or else Nkind
(Par
) = N_Unchecked_Type_Conversion
351 if Ekind
(Subp
) = E_Function
then
353 ("call to abstract function must be dispatching", N
);
355 -- This error can occur for a procedure in the case of a
356 -- call to an abstract formal procedure with a statically
361 ("call to abstract procedure must be dispatching",
370 end Check_Dispatching_Context
;
372 -- Start of processing for Check_Dispatching_Call
375 -- Find a controlling argument, if any
377 if Present
(Parameter_Associations
(N
)) then
378 Actual
:= First_Actual
(N
);
380 Subp_Entity
:= Entity
(Name
(N
));
381 Formal
:= First_Formal
(Subp_Entity
);
383 while Present
(Actual
) loop
384 Control
:= Find_Controlling_Arg
(Actual
);
385 exit when Present
(Control
);
387 -- Check for the case where the actual is a tag-indeterminate call
388 -- whose result type is different than the tagged type associated
389 -- with the containing call, but is an ancestor of the type.
391 if Is_Controlling_Formal
(Formal
)
392 and then Is_Tag_Indeterminate
(Actual
)
393 and then Base_Type
(Etype
(Actual
)) /= Base_Type
(Etype
(Formal
))
394 and then Is_Ancestor
(Etype
(Actual
), Etype
(Formal
))
396 Indeterm_Ancestor_Call
:= True;
397 Indeterm_Ctrl_Type
:= Etype
(Formal
);
399 -- If the formal is controlling but the actual is not, the type
400 -- of the actual is statically known, and may be used as the
401 -- controlling tag for some other-indeterminate actual.
403 elsif Is_Controlling_Formal
(Formal
)
404 and then Is_Entity_Name
(Actual
)
405 and then Is_Tagged_Type
(Etype
(Actual
))
407 Static_Tag
:= Actual
;
410 Next_Actual
(Actual
);
411 Next_Formal
(Formal
);
414 -- If the call doesn't have a controlling actual but does have
415 -- an indeterminate actual that requires dispatching treatment,
416 -- then an object is needed that will serve as the controlling
417 -- argument for a dispatching call on the indeterminate actual.
418 -- This can only occur in the unusual situation of a default
419 -- actual given by a tag-indeterminate call and where the type
420 -- of the call is an ancestor of the type associated with a
421 -- containing call to an inherited operation (see AI-239).
422 -- Rather than create an object of the tagged type, which would
423 -- be problematic for various reasons (default initialization,
424 -- discriminants), the tag of the containing call's associated
425 -- tagged type is directly used to control the dispatching.
428 and then Indeterm_Ancestor_Call
429 and then No
(Static_Tag
)
432 Make_Attribute_Reference
(Loc
,
433 Prefix
=> New_Occurrence_Of
(Indeterm_Ctrl_Type
, Loc
),
434 Attribute_Name
=> Name_Tag
);
439 if Present
(Control
) then
441 -- Verify that no controlling arguments are statically tagged
444 Write_Str
("Found Dispatching call");
449 Actual
:= First_Actual
(N
);
451 while Present
(Actual
) loop
452 if Actual
/= Control
then
454 if not Is_Controlling_Actual
(Actual
) then
455 null; -- Can be anything
457 elsif Is_Dynamically_Tagged
(Actual
) then
458 null; -- Valid parameter
460 elsif Is_Tag_Indeterminate
(Actual
) then
462 -- The tag is inherited from the enclosing call (the
463 -- node we are currently analyzing). Explicitly expand
464 -- the actual, since the previous call to Expand
465 -- (from Resolve_Call) had no way of knowing about
466 -- the required dispatching.
468 Propagate_Tag
(Control
, Actual
);
472 ("controlling argument is not dynamically tagged",
478 Next_Actual
(Actual
);
481 -- Mark call as a dispatching call
483 Set_Controlling_Argument
(N
, Control
);
484 Check_Restriction
(No_Dispatching_Calls
, N
);
486 -- If there is a statically tagged actual and a tag-indeterminate
487 -- call to a function of the ancestor (such as that provided by a
488 -- default), then treat this as a dispatching call and propagate
489 -- the tag to the tag-indeterminate call(s).
491 elsif Present
(Static_Tag
) and then Indeterm_Ancestor_Call
then
493 Make_Attribute_Reference
(Loc
,
495 New_Occurrence_Of
(Etype
(Static_Tag
), Loc
),
496 Attribute_Name
=> Name_Tag
);
500 Actual
:= First_Actual
(N
);
501 Formal
:= First_Formal
(Subp_Entity
);
502 while Present
(Actual
) loop
503 if Is_Tag_Indeterminate
(Actual
)
504 and then Is_Controlling_Formal
(Formal
)
506 Propagate_Tag
(Control
, Actual
);
509 Next_Actual
(Actual
);
510 Next_Formal
(Formal
);
513 Check_Dispatching_Context
;
516 -- The call is not dispatching, so check that there aren't any
517 -- tag-indeterminate abstract calls left.
519 Actual
:= First_Actual
(N
);
520 while Present
(Actual
) loop
521 if Is_Tag_Indeterminate
(Actual
) then
523 -- Function call case
525 if Nkind
(Original_Node
(Actual
)) = N_Function_Call
then
526 Func
:= Entity
(Name
(Original_Node
(Actual
)));
528 -- If the actual is an attribute then it can't be abstract
529 -- (the only current case of a tag-indeterminate attribute
530 -- is the stream Input attribute).
533 Nkind
(Original_Node
(Actual
)) = N_Attribute_Reference
537 -- Only other possibility is a qualified expression whose
538 -- constituent expression is itself a call.
544 (Expression
(Original_Node
(Actual
)))));
547 if Present
(Func
) and then Is_Abstract_Subprogram
(Func
) then
549 "call to abstract function must be dispatching", N
);
553 Next_Actual
(Actual
);
556 Check_Dispatching_Context
;
560 -- If dispatching on result, the enclosing call, if any, will
561 -- determine the controlling argument. Otherwise this is the
562 -- primitive operation of the root type.
564 Check_Dispatching_Context
;
566 end Check_Dispatching_Call
;
568 ---------------------------------
569 -- Check_Dispatching_Operation --
570 ---------------------------------
572 procedure Check_Dispatching_Operation
(Subp
, Old_Subp
: Entity_Id
) is
573 Tagged_Type
: Entity_Id
;
574 Has_Dispatching_Parent
: Boolean := False;
575 Body_Is_Last_Primitive
: Boolean := False;
577 function Is_Visibly_Controlled
(T
: Entity_Id
) return Boolean;
578 -- Check whether T is derived from a visibly controlled type.
579 -- This is true if the root type is declared in Ada.Finalization.
580 -- If T is derived instead from a private type whose full view
581 -- is controlled, an explicit Initialize/Adjust/Finalize subprogram
582 -- does not override the inherited one.
584 ---------------------------
585 -- Is_Visibly_Controlled --
586 ---------------------------
588 function Is_Visibly_Controlled
(T
: Entity_Id
) return Boolean is
589 Root
: constant Entity_Id
:= Root_Type
(T
);
591 return Chars
(Scope
(Root
)) = Name_Finalization
592 and then Chars
(Scope
(Scope
(Root
))) = Name_Ada
593 and then Scope
(Scope
(Scope
(Root
))) = Standard_Standard
;
594 end Is_Visibly_Controlled
;
596 -- Start of processing for Check_Dispatching_Operation
599 if Ekind
(Subp
) /= E_Procedure
and then Ekind
(Subp
) /= E_Function
then
603 Set_Is_Dispatching_Operation
(Subp
, False);
604 Tagged_Type
:= Find_Dispatching_Type
(Subp
);
608 if Ada_Version
= Ada_05
609 and then Present
(Tagged_Type
)
610 and then Is_Concurrent_Type
(Tagged_Type
)
612 -- Protect the frontend against previously detected errors
614 if No
(Corresponding_Record_Type
(Tagged_Type
)) then
618 Tagged_Type
:= Corresponding_Record_Type
(Tagged_Type
);
621 -- (AI-345): The task body procedure is not a primitive of the tagged
624 if Present
(Tagged_Type
)
625 and then Is_Concurrent_Record_Type
(Tagged_Type
)
626 and then Present
(Corresponding_Concurrent_Type
(Tagged_Type
))
627 and then Is_Task_Type
(Corresponding_Concurrent_Type
(Tagged_Type
))
628 and then Subp
= Get_Task_Body_Procedure
629 (Corresponding_Concurrent_Type
(Tagged_Type
))
634 -- If Subp is derived from a dispatching operation then it should
635 -- always be treated as dispatching. In this case various checks
636 -- below will be bypassed. Makes sure that late declarations for
637 -- inherited private subprograms are treated as dispatching, even
638 -- if the associated tagged type is already frozen.
640 Has_Dispatching_Parent
:=
641 Present
(Alias
(Subp
))
642 and then Is_Dispatching_Operation
(Alias
(Subp
));
644 if No
(Tagged_Type
) then
646 -- Ada 2005 (AI-251): Check that Subp is not a primitive associated
647 -- with an abstract interface type unless the interface acts as a
648 -- parent type in a derivation. If the interface type is a formal
649 -- type then the operation is not primitive and therefore legal.
656 E
:= First_Entity
(Subp
);
657 while Present
(E
) loop
659 -- For an access parameter, check designated type.
661 if Ekind
(Etype
(E
)) = E_Anonymous_Access_Type
then
662 Typ
:= Designated_Type
(Etype
(E
));
667 if Comes_From_Source
(Subp
)
668 and then Is_Interface
(Typ
)
669 and then not Is_Class_Wide_Type
(Typ
)
670 and then not Is_Derived_Type
(Typ
)
671 and then not Is_Generic_Type
(Typ
)
672 and then not In_Instance
674 Error_Msg_N
("?declaration of& is too late!", Subp
);
676 ("\spec should appear immediately after declaration of &!",
684 -- In case of functions check also the result type
686 if Ekind
(Subp
) = E_Function
then
687 if Is_Access_Type
(Etype
(Subp
)) then
688 Typ
:= Designated_Type
(Etype
(Subp
));
693 if not Is_Class_Wide_Type
(Typ
)
694 and then Is_Interface
(Typ
)
695 and then not Is_Derived_Type
(Typ
)
697 Error_Msg_N
("?declaration of& is too late!", Subp
);
699 ("\spec should appear immediately after declaration of &!",
707 -- The subprograms build internally after the freezing point (such as
708 -- the Init procedure) are not primitives
710 elsif Is_Frozen
(Tagged_Type
)
711 and then not Comes_From_Source
(Subp
)
712 and then not Has_Dispatching_Parent
716 -- The operation may be a child unit, whose scope is the defining
717 -- package, but which is not a primitive operation of the type.
719 elsif Is_Child_Unit
(Subp
) then
722 -- If the subprogram is not defined in a package spec, the only case
723 -- where it can be a dispatching op is when it overrides an operation
724 -- before the freezing point of the type.
726 elsif ((not Is_Package_Or_Generic_Package
(Scope
(Subp
)))
727 or else In_Package_Body
(Scope
(Subp
)))
728 and then not Has_Dispatching_Parent
730 if not Comes_From_Source
(Subp
)
731 or else (Present
(Old_Subp
) and then not Is_Frozen
(Tagged_Type
))
735 -- If the type is already frozen, the overriding is not allowed
736 -- except when Old_Subp is not a dispatching operation (which
737 -- can occur when Old_Subp was inherited by an untagged type).
738 -- However, a body with no previous spec freezes the type "after"
739 -- its declaration, and therefore is a legal overriding (unless
740 -- the type has already been frozen). Only the first such body
743 elsif Present
(Old_Subp
)
744 and then Is_Dispatching_Operation
(Old_Subp
)
746 if Comes_From_Source
(Subp
)
748 (Nkind
(Unit_Declaration_Node
(Subp
)) = N_Subprogram_Body
749 or else Nkind
(Unit_Declaration_Node
(Subp
)) in N_Body_Stub
)
752 Subp_Body
: constant Node_Id
:= Unit_Declaration_Node
(Subp
);
753 Decl_Item
: Node_Id
:= Next
(Parent
(Tagged_Type
));
756 -- ??? The checks here for whether the type has been
757 -- frozen prior to the new body are not complete. It's
758 -- not simple to check frozenness at this point since
759 -- the body has already caused the type to be prematurely
760 -- frozen in Analyze_Declarations, but we're forced to
761 -- recheck this here because of the odd rule interpretation
762 -- that allows the overriding if the type wasn't frozen
763 -- prior to the body. The freezing action should probably
764 -- be delayed until after the spec is seen, but that's
765 -- a tricky change to the delicate freezing code.
767 -- Look at each declaration following the type up
768 -- until the new subprogram body. If any of the
769 -- declarations is a body then the type has been
770 -- frozen already so the overriding primitive is
773 while Present
(Decl_Item
)
774 and then (Decl_Item
/= Subp_Body
)
776 if Comes_From_Source
(Decl_Item
)
777 and then (Nkind
(Decl_Item
) in N_Proper_Body
778 or else Nkind
(Decl_Item
) in N_Body_Stub
)
780 Error_Msg_N
("overriding of& is too late!", Subp
);
782 ("\spec should appear immediately after the type!",
790 -- If the subprogram doesn't follow in the list of
791 -- declarations including the type then the type
792 -- has definitely been frozen already and the body
795 if No
(Decl_Item
) then
796 Error_Msg_N
("overriding of& is too late!", Subp
);
798 ("\spec should appear immediately after the type!",
801 elsif Is_Frozen
(Subp
) then
803 -- The subprogram body declares a primitive operation.
804 -- if the subprogram is already frozen, we must update
805 -- its dispatching information explicitly here. The
806 -- information is taken from the overridden subprogram.
807 -- We must also generate a cross-reference entry because
808 -- references to other primitives were already created
809 -- when type was frozen.
811 Body_Is_Last_Primitive
:= True;
813 if Present
(DTC_Entity
(Old_Subp
)) then
814 Set_DTC_Entity
(Subp
, DTC_Entity
(Old_Subp
));
815 Set_DT_Position
(Subp
, DT_Position
(Old_Subp
));
817 if not Restriction_Active
(No_Dispatching_Calls
) then
818 if Building_Static_DT
(Tagged_Type
) then
820 -- If the static dispatch table has not been
821 -- built then there is nothing else to do now;
822 -- otherwise we notify that we cannot build the
823 -- static dispatch table.
825 if Has_Dispatch_Table
(Tagged_Type
) then
827 ("overriding of& is too late for building" &
828 " static dispatch tables!", Subp
);
830 ("\spec should appear immediately after" &
835 Register_Primitive
(Sloc
(Subp_Body
),
837 Ins_Nod
=> Subp_Body
);
840 Generate_Reference
(Tagged_Type
, Subp
, 'p', False);
847 Error_Msg_N
("overriding of& is too late!", Subp
);
849 ("\subprogram spec should appear immediately after the type!",
853 -- If the type is not frozen yet and we are not in the overriding
854 -- case it looks suspiciously like an attempt to define a primitive
857 elsif not Is_Frozen
(Tagged_Type
) then
859 ("?not dispatching (must be defined in a package spec)", Subp
);
862 -- When the type is frozen, it is legitimate to define a new
863 -- non-primitive operation.
869 -- Now, we are sure that the scope is a package spec. If the subprogram
870 -- is declared after the freezing point of the type that's an error
872 elsif Is_Frozen
(Tagged_Type
) and then not Has_Dispatching_Parent
then
873 Error_Msg_N
("this primitive operation is declared too late", Subp
);
875 ("?no primitive operations for& after this line",
876 Freeze_Node
(Tagged_Type
),
881 Check_Controlling_Formals
(Tagged_Type
, Subp
);
883 -- Now it should be a correct primitive operation, put it in the list
885 if Present
(Old_Subp
) then
887 -- If the type has interfaces we complete this check after we
888 -- set attribute Is_Dispatching_Operation
890 Check_Subtype_Conformant
(Subp
, Old_Subp
);
892 if (Chars
(Subp
) = Name_Initialize
893 or else Chars
(Subp
) = Name_Adjust
894 or else Chars
(Subp
) = Name_Finalize
)
895 and then Is_Controlled
(Tagged_Type
)
896 and then not Is_Visibly_Controlled
(Tagged_Type
)
898 Set_Is_Overriding_Operation
(Subp
, False);
900 ("operation does not override inherited&?", Subp
, Subp
);
902 Override_Dispatching_Operation
(Tagged_Type
, Old_Subp
, Subp
);
903 Set_Is_Overriding_Operation
(Subp
);
905 -- Ada 2005 (AI-251): In case of late overriding of a primitive
906 -- that covers abstract interface subprograms we must register it
907 -- in all the secondary dispatch tables associated with abstract
910 if Body_Is_Last_Primitive
then
912 Subp_Body
: constant Node_Id
:= Unit_Declaration_Node
(Subp
);
917 Elmt
:= First_Elmt
(Primitive_Operations
(Tagged_Type
));
918 while Present
(Elmt
) loop
921 if Present
(Alias
(Prim
))
922 and then Present
(Interface_Alias
(Prim
))
923 and then Alias
(Prim
) = Subp
925 Register_Primitive
(Sloc
(Prim
),
927 Ins_Nod
=> Subp_Body
);
933 -- Redisplay the contents of the updated dispatch table
935 if Debug_Flag_ZZ
then
936 Write_Str
("Late overriding: ");
937 Write_DT
(Tagged_Type
);
943 -- If no old subprogram, then we add this as a dispatching operation,
944 -- but we avoid doing this if an error was posted, to prevent annoying
947 elsif not Error_Posted
(Subp
) then
948 Add_Dispatching_Operation
(Tagged_Type
, Subp
);
951 Set_Is_Dispatching_Operation
(Subp
, True);
953 -- Ada 2005 (AI-251): If the type implements interfaces we must check
954 -- subtype conformance against all the interfaces covered by this
957 if Present
(Old_Subp
)
958 and then Has_Interfaces
(Tagged_Type
)
961 Ifaces_List
: Elist_Id
;
962 Iface_Elmt
: Elmt_Id
;
963 Iface_Prim_Elmt
: Elmt_Id
;
964 Iface_Prim
: Entity_Id
;
968 Collect_Interfaces
(Tagged_Type
, Ifaces_List
);
970 Iface_Elmt
:= First_Elmt
(Ifaces_List
);
971 while Present
(Iface_Elmt
) loop
972 if not Is_Ancestor
(Node
(Iface_Elmt
), Tagged_Type
) then
974 First_Elmt
(Primitive_Operations
(Node
(Iface_Elmt
)));
975 while Present
(Iface_Prim_Elmt
) loop
976 Iface_Prim
:= Node
(Iface_Prim_Elmt
);
978 if Is_Interface_Conformant
979 (Tagged_Type
, Iface_Prim
, Subp
)
981 -- Handle procedures, functions whose return type
982 -- matches, or functions not returning interfaces
984 if Ekind
(Subp
) = E_Procedure
985 or else Etype
(Iface_Prim
) = Etype
(Subp
)
986 or else not Is_Interface
(Etype
(Iface_Prim
))
988 Check_Subtype_Conformant
990 Old_Id
=> Iface_Prim
,
992 Skip_Controlling_Formals
=> True);
994 -- Handle functions returning interfaces
996 elsif Implements_Interface
997 (Etype
(Subp
), Etype
(Iface_Prim
))
999 -- Temporarily force both entities to return the
1000 -- same type. Required because Subtype_Conformant
1001 -- does not handle this case.
1003 Ret_Typ
:= Etype
(Iface_Prim
);
1004 Set_Etype
(Iface_Prim
, Etype
(Subp
));
1006 Check_Subtype_Conformant
1008 Old_Id
=> Iface_Prim
,
1010 Skip_Controlling_Formals
=> True);
1012 Set_Etype
(Iface_Prim
, Ret_Typ
);
1016 Next_Elmt
(Iface_Prim_Elmt
);
1020 Next_Elmt
(Iface_Elmt
);
1025 if not Body_Is_Last_Primitive
then
1026 Set_DT_Position
(Subp
, No_Uint
);
1028 elsif Has_Controlled_Component
(Tagged_Type
)
1030 (Chars
(Subp
) = Name_Initialize
1031 or else Chars
(Subp
) = Name_Adjust
1032 or else Chars
(Subp
) = Name_Finalize
)
1035 F_Node
: constant Node_Id
:= Freeze_Node
(Tagged_Type
);
1039 Old_Spec
: Entity_Id
;
1041 C_Names
: constant array (1 .. 3) of Name_Id
:=
1046 D_Names
: constant array (1 .. 3) of TSS_Name_Type
:=
1047 (TSS_Deep_Initialize
,
1052 -- Remove previous controlled function, which was constructed
1053 -- and analyzed when the type was frozen. This requires
1054 -- removing the body of the redefined primitive, as well as
1055 -- its specification if needed (there is no spec created for
1056 -- Deep_Initialize, see exp_ch3.adb). We must also dismantle
1057 -- the exception information that may have been generated for
1058 -- it when front end zero-cost tables are enabled.
1060 for J
in D_Names
'Range loop
1061 Old_P
:= TSS
(Tagged_Type
, D_Names
(J
));
1064 and then Chars
(Subp
) = C_Names
(J
)
1066 Old_Bod
:= Unit_Declaration_Node
(Old_P
);
1068 Set_Is_Eliminated
(Old_P
);
1069 Set_Scope
(Old_P
, Scope
(Current_Scope
));
1071 if Nkind
(Old_Bod
) = N_Subprogram_Body
1072 and then Present
(Corresponding_Spec
(Old_Bod
))
1074 Old_Spec
:= Corresponding_Spec
(Old_Bod
);
1075 Set_Has_Completion
(Old_Spec
, False);
1080 Build_Late_Proc
(Tagged_Type
, Chars
(Subp
));
1082 -- The new operation is added to the actions of the freeze
1083 -- node for the type, but this node has already been analyzed,
1084 -- so we must retrieve and analyze explicitly the new body.
1087 and then Present
(Actions
(F_Node
))
1089 Decl
:= Last
(Actions
(F_Node
));
1094 end Check_Dispatching_Operation
;
1096 ------------------------------------------
1097 -- Check_Operation_From_Incomplete_Type --
1098 ------------------------------------------
1100 procedure Check_Operation_From_Incomplete_Type
1104 Full
: constant Entity_Id
:= Full_View
(Typ
);
1105 Parent_Typ
: constant Entity_Id
:= Etype
(Full
);
1106 Old_Prim
: constant Elist_Id
:= Primitive_Operations
(Parent_Typ
);
1107 New_Prim
: constant Elist_Id
:= Primitive_Operations
(Full
);
1109 Prev
: Elmt_Id
:= No_Elmt
;
1111 function Derives_From
(Proc
: Entity_Id
) return Boolean;
1112 -- Check that Subp has the signature of an operation derived from Proc.
1113 -- Subp has an access parameter that designates Typ.
1119 function Derives_From
(Proc
: Entity_Id
) return Boolean is
1123 if Chars
(Proc
) /= Chars
(Subp
) then
1127 F1
:= First_Formal
(Proc
);
1128 F2
:= First_Formal
(Subp
);
1130 while Present
(F1
) and then Present
(F2
) loop
1132 if Ekind
(Etype
(F1
)) = E_Anonymous_Access_Type
then
1134 if Ekind
(Etype
(F2
)) /= E_Anonymous_Access_Type
then
1137 elsif Designated_Type
(Etype
(F1
)) = Parent_Typ
1138 and then Designated_Type
(Etype
(F2
)) /= Full
1143 elsif Ekind
(Etype
(F2
)) = E_Anonymous_Access_Type
then
1146 elsif Etype
(F1
) /= Etype
(F2
) then
1154 return No
(F1
) and then No
(F2
);
1157 -- Start of processing for Check_Operation_From_Incomplete_Type
1160 -- The operation may override an inherited one, or may be a new one
1161 -- altogether. The inherited operation will have been hidden by the
1162 -- current one at the point of the type derivation, so it does not
1163 -- appear in the list of primitive operations of the type. We have to
1164 -- find the proper place of insertion in the list of primitive opera-
1165 -- tions by iterating over the list for the parent type.
1167 Op1
:= First_Elmt
(Old_Prim
);
1168 Op2
:= First_Elmt
(New_Prim
);
1170 while Present
(Op1
) and then Present
(Op2
) loop
1172 if Derives_From
(Node
(Op1
)) then
1176 -- Avoid adding it to the list of primitives if already there!
1178 if Node
(Op2
) /= Subp
then
1179 Prepend_Elmt
(Subp
, New_Prim
);
1183 Insert_Elmt_After
(Subp
, Prev
);
1194 -- Operation is a new primitive
1196 Append_Elmt
(Subp
, New_Prim
);
1197 end Check_Operation_From_Incomplete_Type
;
1199 ---------------------------------------
1200 -- Check_Operation_From_Private_View --
1201 ---------------------------------------
1203 procedure Check_Operation_From_Private_View
(Subp
, Old_Subp
: Entity_Id
) is
1204 Tagged_Type
: Entity_Id
;
1207 if Is_Dispatching_Operation
(Alias
(Subp
)) then
1208 Set_Scope
(Subp
, Current_Scope
);
1209 Tagged_Type
:= Find_Dispatching_Type
(Subp
);
1211 -- Add Old_Subp to primitive operations if not already present.
1213 if Present
(Tagged_Type
) and then Is_Tagged_Type
(Tagged_Type
) then
1214 Append_Unique_Elmt
(Old_Subp
, Primitive_Operations
(Tagged_Type
));
1216 -- If Old_Subp isn't already marked as dispatching then
1217 -- this is the case of an operation of an untagged private
1218 -- type fulfilled by a tagged type that overrides an
1219 -- inherited dispatching operation, so we set the necessary
1220 -- dispatching attributes here.
1222 if not Is_Dispatching_Operation
(Old_Subp
) then
1224 -- If the untagged type has no discriminants, and the full
1225 -- view is constrained, there will be a spurious mismatch
1226 -- of subtypes on the controlling arguments, because the tagged
1227 -- type is the internal base type introduced in the derivation.
1228 -- Use the original type to verify conformance, rather than the
1231 if not Comes_From_Source
(Tagged_Type
)
1232 and then Has_Discriminants
(Tagged_Type
)
1237 Formal
:= First_Formal
(Old_Subp
);
1238 while Present
(Formal
) loop
1239 if Tagged_Type
= Base_Type
(Etype
(Formal
)) then
1240 Tagged_Type
:= Etype
(Formal
);
1243 Next_Formal
(Formal
);
1247 if Tagged_Type
= Base_Type
(Etype
(Old_Subp
)) then
1248 Tagged_Type
:= Etype
(Old_Subp
);
1252 Check_Controlling_Formals
(Tagged_Type
, Old_Subp
);
1253 Set_Is_Dispatching_Operation
(Old_Subp
, True);
1254 Set_DT_Position
(Old_Subp
, No_Uint
);
1257 -- If the old subprogram is an explicit renaming of some other
1258 -- entity, it is not overridden by the inherited subprogram.
1259 -- Otherwise, update its alias and other attributes.
1261 if Present
(Alias
(Old_Subp
))
1262 and then Nkind
(Unit_Declaration_Node
(Old_Subp
))
1263 /= N_Subprogram_Renaming_Declaration
1265 Set_Alias
(Old_Subp
, Alias
(Subp
));
1267 -- The derived subprogram should inherit the abstractness
1268 -- of the parent subprogram (except in the case of a function
1269 -- returning the type). This sets the abstractness properly
1270 -- for cases where a private extension may have inherited
1271 -- an abstract operation, but the full type is derived from
1272 -- a descendant type and inherits a nonabstract version.
1274 if Etype
(Subp
) /= Tagged_Type
then
1275 Set_Is_Abstract_Subprogram
1276 (Old_Subp
, Is_Abstract_Subprogram
(Alias
(Subp
)));
1281 end Check_Operation_From_Private_View
;
1283 --------------------------
1284 -- Find_Controlling_Arg --
1285 --------------------------
1287 function Find_Controlling_Arg
(N
: Node_Id
) return Node_Id
is
1288 Orig_Node
: constant Node_Id
:= Original_Node
(N
);
1292 if Nkind
(Orig_Node
) = N_Qualified_Expression
then
1293 return Find_Controlling_Arg
(Expression
(Orig_Node
));
1296 -- Dispatching on result case. If expansion is disabled, the node still
1297 -- has the structure of a function call. However, if the function name
1298 -- is an operator and the call was given in infix form, the original
1299 -- node has no controlling result and we must examine the current node.
1301 if Nkind
(N
) = N_Function_Call
1302 and then Present
(Controlling_Argument
(N
))
1303 and then Has_Controlling_Result
(Entity
(Name
(N
)))
1305 return Controlling_Argument
(N
);
1307 -- If expansion is enabled, the call may have been transformed into
1308 -- an indirect call, and we need to recover the original node.
1310 elsif Nkind
(Orig_Node
) = N_Function_Call
1311 and then Present
(Controlling_Argument
(Orig_Node
))
1312 and then Has_Controlling_Result
(Entity
(Name
(Orig_Node
)))
1314 return Controlling_Argument
(Orig_Node
);
1318 elsif Is_Controlling_Actual
(N
)
1320 (Nkind
(Parent
(N
)) = N_Qualified_Expression
1321 and then Is_Controlling_Actual
(Parent
(N
)))
1325 if Is_Access_Type
(Typ
) then
1326 -- In the case of an Access attribute, use the type of
1327 -- the prefix, since in the case of an actual for an
1328 -- access parameter, the attribute's type may be of a
1329 -- specific designated type, even though the prefix
1330 -- type is class-wide.
1332 if Nkind
(N
) = N_Attribute_Reference
then
1333 Typ
:= Etype
(Prefix
(N
));
1335 -- An allocator is dispatching if the type of qualified
1336 -- expression is class_wide, in which case this is the
1337 -- controlling type.
1339 elsif Nkind
(Orig_Node
) = N_Allocator
1340 and then Nkind
(Expression
(Orig_Node
)) = N_Qualified_Expression
1342 Typ
:= Etype
(Expression
(Orig_Node
));
1345 Typ
:= Designated_Type
(Typ
);
1349 if Is_Class_Wide_Type
(Typ
)
1351 (Nkind
(Parent
(N
)) = N_Qualified_Expression
1352 and then Is_Access_Type
(Etype
(N
))
1353 and then Is_Class_Wide_Type
(Designated_Type
(Etype
(N
))))
1360 end Find_Controlling_Arg
;
1362 ---------------------------
1363 -- Find_Dispatching_Type --
1364 ---------------------------
1366 function Find_Dispatching_Type
(Subp
: Entity_Id
) return Entity_Id
is
1368 Ctrl_Type
: Entity_Id
;
1371 if Present
(DTC_Entity
(Subp
)) then
1372 return Scope
(DTC_Entity
(Subp
));
1375 Formal
:= First_Formal
(Subp
);
1376 while Present
(Formal
) loop
1377 Ctrl_Type
:= Check_Controlling_Type
(Etype
(Formal
), Subp
);
1379 if Present
(Ctrl_Type
) then
1383 Next_Formal
(Formal
);
1386 -- The subprogram may also be dispatching on result
1388 if Present
(Etype
(Subp
)) then
1389 Ctrl_Type
:= Check_Controlling_Type
(Etype
(Subp
), Subp
);
1391 if Present
(Ctrl_Type
) then
1398 end Find_Dispatching_Type
;
1400 ---------------------------------------
1401 -- Find_Primitive_Covering_Interface --
1402 ---------------------------------------
1404 function Find_Primitive_Covering_Interface
1405 (Tagged_Type
: Entity_Id
;
1406 Iface_Prim
: Entity_Id
) return Entity_Id
1411 pragma Assert
(Is_Interface
(Find_Dispatching_Type
(Iface_Prim
))
1412 or else (Present
(Alias
(Iface_Prim
))
1415 (Find_Dispatching_Type
(Ultimate_Alias
(Iface_Prim
)))));
1417 E
:= Current_Entity
(Iface_Prim
);
1418 while Present
(E
) loop
1419 if Is_Subprogram
(E
)
1420 and then Is_Dispatching_Operation
(E
)
1421 and then Is_Interface_Conformant
(Tagged_Type
, Iface_Prim
, E
)
1430 end Find_Primitive_Covering_Interface
;
1432 ---------------------------
1433 -- Is_Dynamically_Tagged --
1434 ---------------------------
1436 function Is_Dynamically_Tagged
(N
: Node_Id
) return Boolean is
1438 if Nkind
(N
) = N_Error
then
1441 return Find_Controlling_Arg
(N
) /= Empty
;
1443 end Is_Dynamically_Tagged
;
1445 --------------------------
1446 -- Is_Tag_Indeterminate --
1447 --------------------------
1449 function Is_Tag_Indeterminate
(N
: Node_Id
) return Boolean is
1452 Orig_Node
: constant Node_Id
:= Original_Node
(N
);
1455 if Nkind
(Orig_Node
) = N_Function_Call
1456 and then Is_Entity_Name
(Name
(Orig_Node
))
1458 Nam
:= Entity
(Name
(Orig_Node
));
1460 if not Has_Controlling_Result
(Nam
) then
1463 -- An explicit dereference means that the call has already been
1464 -- expanded and there is no tag to propagate.
1466 elsif Nkind
(N
) = N_Explicit_Dereference
then
1469 -- If there are no actuals, the call is tag-indeterminate
1471 elsif No
(Parameter_Associations
(Orig_Node
)) then
1475 Actual
:= First_Actual
(Orig_Node
);
1476 while Present
(Actual
) loop
1477 if Is_Controlling_Actual
(Actual
)
1478 and then not Is_Tag_Indeterminate
(Actual
)
1480 return False; -- one operand is dispatching
1483 Next_Actual
(Actual
);
1489 elsif Nkind
(Orig_Node
) = N_Qualified_Expression
then
1490 return Is_Tag_Indeterminate
(Expression
(Orig_Node
));
1492 -- Case of a call to the Input attribute (possibly rewritten), which is
1493 -- always tag-indeterminate except when its prefix is a Class attribute.
1495 elsif Nkind
(Orig_Node
) = N_Attribute_Reference
1497 Get_Attribute_Id
(Attribute_Name
(Orig_Node
)) = Attribute_Input
1499 Nkind
(Prefix
(Orig_Node
)) /= N_Attribute_Reference
1503 -- In Ada 2005 a function that returns an anonymous access type can
1504 -- dispatching, and the dereference of a call to such a function
1505 -- is also tag-indeterminate.
1507 elsif Nkind
(Orig_Node
) = N_Explicit_Dereference
1508 and then Ada_Version
>= Ada_05
1510 return Is_Tag_Indeterminate
(Prefix
(Orig_Node
));
1515 end Is_Tag_Indeterminate
;
1517 ------------------------------------
1518 -- Override_Dispatching_Operation --
1519 ------------------------------------
1521 procedure Override_Dispatching_Operation
1522 (Tagged_Type
: Entity_Id
;
1523 Prev_Op
: Entity_Id
;
1530 -- Diagnose failure to match No_Return in parent (Ada-2005, AI-414, but
1531 -- we do it unconditionally in Ada 95 now, since this is our pragma!)
1533 if No_Return
(Prev_Op
) and then not No_Return
(New_Op
) then
1534 Error_Msg_N
("procedure & must have No_Return pragma", New_Op
);
1535 Error_Msg_N
("\since overridden procedure has No_Return", New_Op
);
1538 -- If there is no previous operation to override, the type declaration
1539 -- was malformed, and an error must have been emitted already.
1541 Elmt
:= First_Elmt
(Primitive_Operations
(Tagged_Type
));
1542 while Present
(Elmt
)
1543 and then Node
(Elmt
) /= Prev_Op
1552 Replace_Elmt
(Elmt
, New_Op
);
1554 if Ada_Version
>= Ada_05
1555 and then Has_Interfaces
(Tagged_Type
)
1557 -- Ada 2005 (AI-251): Update the attribute alias of all the aliased
1558 -- entities of the overridden primitive to reference New_Op, and also
1559 -- propagate the proper value of Is_Abstract_Subprogram. Verify
1560 -- that the new operation is subtype conformant with the interface
1561 -- operations that it implements (for operations inherited from the
1562 -- parent itself, this check is made when building the derived type).
1564 -- Note: This code is only executed in case of late overriding
1566 Elmt
:= First_Elmt
(Primitive_Operations
(Tagged_Type
));
1567 while Present
(Elmt
) loop
1568 Prim
:= Node
(Elmt
);
1570 if Prim
= New_Op
then
1573 -- Note: The check on Is_Subprogram protects the frontend against
1574 -- reading attributes in entities that are not yet fully decorated
1576 elsif Is_Subprogram
(Prim
)
1577 and then Present
(Interface_Alias
(Prim
))
1578 and then Alias
(Prim
) = Prev_Op
1579 and then Present
(Etype
(New_Op
))
1581 Set_Alias
(Prim
, New_Op
);
1582 Check_Subtype_Conformant
(New_Op
, Prim
);
1583 Set_Is_Abstract_Subprogram
(Prim
,
1584 Is_Abstract_Subprogram
(New_Op
));
1586 -- Ensure that this entity will be expanded to fill the
1587 -- corresponding entry in its dispatch table.
1589 if not Is_Abstract_Subprogram
(Prim
) then
1590 Set_Has_Delayed_Freeze
(Prim
);
1598 if (not Is_Package_Or_Generic_Package
(Current_Scope
))
1599 or else not In_Private_Part
(Current_Scope
)
1601 -- Not a private primitive
1605 else pragma Assert
(Is_Inherited_Operation
(Prev_Op
));
1607 -- Make the overriding operation into an alias of the implicit one.
1608 -- In this fashion a call from outside ends up calling the new body
1609 -- even if non-dispatching, and a call from inside calls the
1610 -- overriding operation because it hides the implicit one. To
1611 -- indicate that the body of Prev_Op is never called, set its
1612 -- dispatch table entity to Empty.
1614 Set_Alias
(Prev_Op
, New_Op
);
1615 Set_DTC_Entity
(Prev_Op
, Empty
);
1618 end Override_Dispatching_Operation
;
1624 procedure Propagate_Tag
(Control
: Node_Id
; Actual
: Node_Id
) is
1625 Call_Node
: Node_Id
;
1629 if Nkind
(Actual
) = N_Function_Call
then
1630 Call_Node
:= Actual
;
1632 elsif Nkind
(Actual
) = N_Identifier
1633 and then Nkind
(Original_Node
(Actual
)) = N_Function_Call
1635 -- Call rewritten as object declaration when stack-checking
1636 -- is enabled. Propagate tag to expression in declaration, which
1637 -- is original call.
1639 Call_Node
:= Expression
(Parent
(Entity
(Actual
)));
1641 -- Ada 2005: If this is a dereference of a call to a function with a
1642 -- dispatching access-result, the tag is propagated when the dereference
1643 -- itself is expanded (see exp_ch6.adb) and there is nothing else to do.
1645 elsif Nkind
(Actual
) = N_Explicit_Dereference
1646 and then Nkind
(Original_Node
(Prefix
(Actual
))) = N_Function_Call
1650 -- Only other possibilities are parenthesized or qualified expression,
1651 -- or an expander-generated unchecked conversion of a function call to
1652 -- a stream Input attribute.
1655 Call_Node
:= Expression
(Actual
);
1658 -- Do not set the Controlling_Argument if already set. This happens
1659 -- in the special case of _Input (see Exp_Attr, case Input).
1661 if No
(Controlling_Argument
(Call_Node
)) then
1662 Set_Controlling_Argument
(Call_Node
, Control
);
1665 Arg
:= First_Actual
(Call_Node
);
1667 while Present
(Arg
) loop
1668 if Is_Tag_Indeterminate
(Arg
) then
1669 Propagate_Tag
(Control
, Arg
);
1675 -- Expansion of dispatching calls is suppressed when VM_Target, because
1676 -- the VM back-ends directly handle the generation of dispatching
1677 -- calls and would have to undo any expansion to an indirect call.
1679 if VM_Target
= No_VM
then
1680 Expand_Dispatching_Call
(Call_Node
);
1682 -- Expansion of a dispatching call results in an indirect call, which in
1683 -- turn causes current values to be killed (see Resolve_Call), so on VM
1684 -- targets we do the call here to ensure consistent warnings between VM
1685 -- and non-VM targets.
1688 Kill_Current_Values
;