1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Aspects; use Aspects;
27 with Atree; use Atree;
28 with Checks; use Checks;
29 with Einfo; use Einfo;
30 with Errout; use Errout;
31 with Expander; use Expander;
32 with Exp_Ch6; use Exp_Ch6;
33 with Exp_Util; use Exp_Util;
34 with Freeze; use Freeze;
36 with Lib.Xref; use Lib.Xref;
37 with Namet; use Namet;
38 with Nlists; use Nlists;
39 with Nmake; use Nmake;
41 with Restrict; use Restrict;
42 with Rident; use Rident;
43 with Rtsfind; use Rtsfind;
45 with Sem_Aux; use Sem_Aux;
46 with Sem_Case; use Sem_Case;
47 with Sem_Ch3; use Sem_Ch3;
48 with Sem_Ch6; use Sem_Ch6;
49 with Sem_Ch8; use Sem_Ch8;
50 with Sem_Dim; use Sem_Dim;
51 with Sem_Disp; use Sem_Disp;
52 with Sem_Elab; use Sem_Elab;
53 with Sem_Eval; use Sem_Eval;
54 with Sem_Res; use Sem_Res;
55 with Sem_Type; use Sem_Type;
56 with Sem_Util; use Sem_Util;
57 with Sem_Warn; use Sem_Warn;
58 with Snames; use Snames;
59 with Stand; use Stand;
60 with Sinfo; use Sinfo;
61 with Targparm; use Targparm;
62 with Tbuild; use Tbuild;
63 with Uintp; use Uintp;
65 package body Sem_Ch5 is
67 Unblocked_Exit_Count : Nat := 0;
68 -- This variable is used when processing if statements, case statements,
69 -- and block statements. It counts the number of exit points that are not
70 -- blocked by unconditional transfer instructions: for IF and CASE, these
71 -- are the branches of the conditional; for a block, they are the statement
72 -- sequence of the block, and the statement sequences of any exception
73 -- handlers that are part of the block. When processing is complete, if
74 -- this count is zero, it means that control cannot fall through the IF,
75 -- CASE or block statement. This is used for the generation of warning
76 -- messages. This variable is recursively saved on entry to processing the
77 -- construct, and restored on exit.
79 procedure Preanalyze_Range (R_Copy : Node_Id);
80 -- Determine expected type of range or domain of iteration of Ada 2012
81 -- loop by analyzing separate copy. Do the analysis and resolution of the
82 -- copy of the bound(s) with expansion disabled, to prevent the generation
83 -- of finalization actions. This prevents memory leaks when the bounds
84 -- contain calls to functions returning controlled arrays or when the
85 -- domain of iteration is a container.
87 ------------------------
88 -- Analyze_Assignment --
89 ------------------------
91 procedure Analyze_Assignment (N : Node_Id) is
92 Lhs : constant Node_Id := Name (N);
93 Rhs : constant Node_Id := Expression (N);
98 procedure Diagnose_Non_Variable_Lhs (N : Node_Id);
99 -- N is the node for the left hand side of an assignment, and it is not
100 -- a variable. This routine issues an appropriate diagnostic.
103 -- This is called to kill current value settings of a simple variable
104 -- on the left hand side. We call it if we find any error in analyzing
105 -- the assignment, and at the end of processing before setting any new
106 -- current values in place.
108 procedure Set_Assignment_Type
110 Opnd_Type : in out Entity_Id);
111 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
112 -- nominal subtype. This procedure is used to deal with cases where the
113 -- nominal subtype must be replaced by the actual subtype.
115 -------------------------------
116 -- Diagnose_Non_Variable_Lhs --
117 -------------------------------
119 procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is
121 -- Not worth posting another error if left hand side already flagged
122 -- as being illegal in some respect.
124 if Error_Posted (N) then
127 -- Some special bad cases of entity names
129 elsif Is_Entity_Name (N) then
131 Ent : constant Entity_Id := Entity (N);
134 if Ekind (Ent) = E_In_Parameter then
136 ("assignment to IN mode parameter not allowed", N);
138 -- Renamings of protected private components are turned into
139 -- constants when compiling a protected function. In the case
140 -- of single protected types, the private component appears
143 elsif (Is_Prival (Ent)
145 (Ekind (Current_Scope) = E_Function
146 or else Ekind (Enclosing_Dynamic_Scope
147 (Current_Scope)) = E_Function))
149 (Ekind (Ent) = E_Component
150 and then Is_Protected_Type (Scope (Ent)))
153 ("protected function cannot modify protected object", N);
155 elsif Ekind (Ent) = E_Loop_Parameter then
157 ("assignment to loop parameter not allowed", N);
161 ("left hand side of assignment must be a variable", N);
165 -- For indexed components or selected components, test prefix
167 elsif Nkind (N) = N_Indexed_Component then
168 Diagnose_Non_Variable_Lhs (Prefix (N));
170 -- Another special case for assignment to discriminant
172 elsif Nkind (N) = N_Selected_Component then
173 if Present (Entity (Selector_Name (N)))
174 and then Ekind (Entity (Selector_Name (N))) = E_Discriminant
177 ("assignment to discriminant not allowed", N);
179 Diagnose_Non_Variable_Lhs (Prefix (N));
183 -- If we fall through, we have no special message to issue!
185 Error_Msg_N ("left hand side of assignment must be a variable", N);
187 end Diagnose_Non_Variable_Lhs;
193 procedure Kill_Lhs is
195 if Is_Entity_Name (Lhs) then
197 Ent : constant Entity_Id := Entity (Lhs);
199 if Present (Ent) then
200 Kill_Current_Values (Ent);
206 -------------------------
207 -- Set_Assignment_Type --
208 -------------------------
210 procedure Set_Assignment_Type
212 Opnd_Type : in out Entity_Id)
215 Require_Entity (Opnd);
217 -- If the assignment operand is an in-out or out parameter, then we
218 -- get the actual subtype (needed for the unconstrained case). If the
219 -- operand is the actual in an entry declaration, then within the
220 -- accept statement it is replaced with a local renaming, which may
221 -- also have an actual subtype.
223 if Is_Entity_Name (Opnd)
224 and then (Ekind (Entity (Opnd)) = E_Out_Parameter
225 or else Ekind (Entity (Opnd)) =
227 or else Ekind (Entity (Opnd)) =
228 E_Generic_In_Out_Parameter
230 (Ekind (Entity (Opnd)) = E_Variable
231 and then Nkind (Parent (Entity (Opnd))) =
232 N_Object_Renaming_Declaration
233 and then Nkind (Parent (Parent (Entity (Opnd)))) =
236 Opnd_Type := Get_Actual_Subtype (Opnd);
238 -- If assignment operand is a component reference, then we get the
239 -- actual subtype of the component for the unconstrained case.
241 elsif Nkind_In (Opnd, N_Selected_Component, N_Explicit_Dereference)
242 and then not Is_Unchecked_Union (Opnd_Type)
244 Decl := Build_Actual_Subtype_Of_Component (Opnd_Type, Opnd);
246 if Present (Decl) then
247 Insert_Action (N, Decl);
248 Mark_Rewrite_Insertion (Decl);
250 Opnd_Type := Defining_Identifier (Decl);
251 Set_Etype (Opnd, Opnd_Type);
252 Freeze_Itype (Opnd_Type, N);
254 elsif Is_Constrained (Etype (Opnd)) then
255 Opnd_Type := Etype (Opnd);
258 -- For slice, use the constrained subtype created for the slice
260 elsif Nkind (Opnd) = N_Slice then
261 Opnd_Type := Etype (Opnd);
263 end Set_Assignment_Type;
265 -- Start of processing for Analyze_Assignment
268 Mark_Coextensions (N, Rhs);
273 -- Ensure that we never do an assignment on a variable marked as
274 -- as Safe_To_Reevaluate.
276 pragma Assert (not Is_Entity_Name (Lhs)
277 or else Ekind (Entity (Lhs)) /= E_Variable
278 or else not Is_Safe_To_Reevaluate (Entity (Lhs)));
280 -- Start type analysis for assignment
284 -- In the most general case, both Lhs and Rhs can be overloaded, and we
285 -- must compute the intersection of the possible types on each side.
287 if Is_Overloaded (Lhs) then
294 Get_First_Interp (Lhs, I, It);
296 while Present (It.Typ) loop
297 if Has_Compatible_Type (Rhs, It.Typ) then
298 if T1 /= Any_Type then
300 -- An explicit dereference is overloaded if the prefix
301 -- is. Try to remove the ambiguity on the prefix, the
302 -- error will be posted there if the ambiguity is real.
304 if Nkind (Lhs) = N_Explicit_Dereference then
307 PI1 : Interp_Index := 0;
313 Get_First_Interp (Prefix (Lhs), PI, PIt);
315 while Present (PIt.Typ) loop
316 if Is_Access_Type (PIt.Typ)
317 and then Has_Compatible_Type
318 (Rhs, Designated_Type (PIt.Typ))
322 Disambiguate (Prefix (Lhs),
325 if PIt = No_Interp then
327 ("ambiguous left-hand side"
328 & " in assignment", Lhs);
331 Resolve (Prefix (Lhs), PIt.Typ);
341 Get_Next_Interp (PI, PIt);
347 ("ambiguous left-hand side in assignment", Lhs);
355 Get_Next_Interp (I, It);
359 if T1 = Any_Type then
361 ("no valid types for left-hand side for assignment", Lhs);
367 -- The resulting assignment type is T1, so now we will resolve the left
368 -- hand side of the assignment using this determined type.
372 -- Cases where Lhs is not a variable
374 if not Is_Variable (Lhs) then
376 -- Ada 2005 (AI-327): Check assignment to the attribute Priority of a
384 if Ada_Version >= Ada_2005 then
386 -- Handle chains of renamings
389 while Nkind (Ent) in N_Has_Entity
390 and then Present (Entity (Ent))
391 and then Present (Renamed_Object (Entity (Ent)))
393 Ent := Renamed_Object (Entity (Ent));
396 if (Nkind (Ent) = N_Attribute_Reference
397 and then Attribute_Name (Ent) = Name_Priority)
399 -- Renamings of the attribute Priority applied to protected
400 -- objects have been previously expanded into calls to the
401 -- Get_Ceiling run-time subprogram.
404 (Nkind (Ent) = N_Function_Call
405 and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
407 Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)))
409 -- The enclosing subprogram cannot be a protected function
412 while not (Is_Subprogram (S)
413 and then Convention (S) = Convention_Protected)
414 and then S /= Standard_Standard
419 if Ekind (S) = E_Function
420 and then Convention (S) = Convention_Protected
423 ("protected function cannot modify protected object",
427 -- Changes of the ceiling priority of the protected object
428 -- are only effective if the Ceiling_Locking policy is in
429 -- effect (AARM D.5.2 (5/2)).
431 if Locking_Policy /= 'C' then
432 Error_Msg_N ("assignment to the attribute PRIORITY has " &
434 Error_Msg_N ("\since no Locking_Policy has been " &
443 Diagnose_Non_Variable_Lhs (Lhs);
446 -- Error of assigning to limited type. We do however allow this in
447 -- certain cases where the front end generates the assignments.
449 elsif Is_Limited_Type (T1)
450 and then not Assignment_OK (Lhs)
451 and then not Assignment_OK (Original_Node (Lhs))
452 and then not Is_Value_Type (T1)
454 -- CPP constructors can only be called in declarations
456 if Is_CPP_Constructor_Call (Rhs) then
457 Error_Msg_N ("invalid use of 'C'P'P constructor", Rhs);
460 ("left hand of assignment must not be limited type", Lhs);
461 Explain_Limited_Type (T1, Lhs);
465 -- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
466 -- abstract. This is only checked when the assignment Comes_From_Source,
467 -- because in some cases the expander generates such assignments (such
468 -- in the _assign operation for an abstract type).
470 elsif Is_Abstract_Type (T1) and then Comes_From_Source (N) then
472 ("target of assignment operation must not be abstract", Lhs);
475 -- Resolution may have updated the subtype, in case the left-hand side
476 -- is a private protected component. Use the correct subtype to avoid
477 -- scoping issues in the back-end.
481 -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
482 -- type. For example:
486 -- type Acc is access P.T;
489 -- with Pkg; use Acc;
490 -- procedure Example is
493 -- A.all := B.all; -- ERROR
496 if Nkind (Lhs) = N_Explicit_Dereference
497 and then Ekind (T1) = E_Incomplete_Type
499 Error_Msg_N ("invalid use of incomplete type", Lhs);
504 -- Now we can complete the resolution of the right hand side
506 Set_Assignment_Type (Lhs, T1);
509 -- This is the point at which we check for an unset reference
511 Check_Unset_Reference (Rhs);
512 Check_Unprotected_Access (Lhs, Rhs);
514 -- Remaining steps are skipped if Rhs was syntactically in error
523 if not Covers (T1, T2) then
524 Wrong_Type (Rhs, Etype (Lhs));
529 -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
530 -- types, use the non-limited view if available
532 if Nkind (Rhs) = N_Explicit_Dereference
533 and then Ekind (T2) = E_Incomplete_Type
534 and then Is_Tagged_Type (T2)
535 and then Present (Non_Limited_View (T2))
537 T2 := Non_Limited_View (T2);
540 Set_Assignment_Type (Rhs, T2);
542 if Total_Errors_Detected /= 0 then
552 if T1 = Any_Type or else T2 = Any_Type then
557 -- If the rhs is class-wide or dynamically tagged, then require the lhs
558 -- to be class-wide. The case where the rhs is a dynamically tagged call
559 -- to a dispatching operation with a controlling access result is
560 -- excluded from this check, since the target has an access type (and
561 -- no tag propagation occurs in that case).
563 if (Is_Class_Wide_Type (T2)
564 or else (Is_Dynamically_Tagged (Rhs)
565 and then not Is_Access_Type (T1)))
566 and then not Is_Class_Wide_Type (T1)
568 Error_Msg_N ("dynamically tagged expression not allowed!", Rhs);
570 elsif Is_Class_Wide_Type (T1)
571 and then not Is_Class_Wide_Type (T2)
572 and then not Is_Tag_Indeterminate (Rhs)
573 and then not Is_Dynamically_Tagged (Rhs)
575 Error_Msg_N ("dynamically tagged expression required!", Rhs);
578 -- Propagate the tag from a class-wide target to the rhs when the rhs
579 -- is a tag-indeterminate call.
581 if Is_Tag_Indeterminate (Rhs) then
582 if Is_Class_Wide_Type (T1) then
583 Propagate_Tag (Lhs, Rhs);
585 elsif Nkind (Rhs) = N_Function_Call
586 and then Is_Entity_Name (Name (Rhs))
587 and then Is_Abstract_Subprogram (Entity (Name (Rhs)))
590 ("call to abstract function must be dispatching", Name (Rhs));
592 elsif Nkind (Rhs) = N_Qualified_Expression
593 and then Nkind (Expression (Rhs)) = N_Function_Call
594 and then Is_Entity_Name (Name (Expression (Rhs)))
596 Is_Abstract_Subprogram (Entity (Name (Expression (Rhs))))
599 ("call to abstract function must be dispatching",
600 Name (Expression (Rhs)));
604 -- Ada 2005 (AI-385): When the lhs type is an anonymous access type,
605 -- apply an implicit conversion of the rhs to that type to force
606 -- appropriate static and run-time accessibility checks. This applies
607 -- as well to anonymous access-to-subprogram types that are component
608 -- subtypes or formal parameters.
610 if Ada_Version >= Ada_2005
611 and then Is_Access_Type (T1)
613 if Is_Local_Anonymous_Access (T1)
614 or else Ekind (T2) = E_Anonymous_Access_Subprogram_Type
616 -- Handle assignment to an Ada 2012 stand-alone object
617 -- of an anonymous access type.
619 or else (Ekind (T1) = E_Anonymous_Access_Type
620 and then Nkind (Associated_Node_For_Itype (T1)) =
621 N_Object_Declaration)
624 Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
625 Analyze_And_Resolve (Rhs, T1);
629 -- Ada 2005 (AI-231): Assignment to not null variable
631 if Ada_Version >= Ada_2005
632 and then Can_Never_Be_Null (T1)
633 and then not Assignment_OK (Lhs)
635 -- Case where we know the right hand side is null
637 if Known_Null (Rhs) then
638 Apply_Compile_Time_Constraint_Error
641 "(Ada 2005) null not allowed in null-excluding objects??",
642 Reason => CE_Null_Not_Allowed);
644 -- We still mark this as a possible modification, that's necessary
645 -- to reset Is_True_Constant, and desirable for xref purposes.
647 Note_Possible_Modification (Lhs, Sure => True);
650 -- If we know the right hand side is non-null, then we convert to the
651 -- target type, since we don't need a run time check in that case.
653 elsif not Can_Never_Be_Null (T2) then
654 Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
655 Analyze_And_Resolve (Rhs, T1);
659 if Is_Scalar_Type (T1) then
660 Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
662 -- For array types, verify that lengths match. If the right hand side
663 -- is a function call that has been inlined, the assignment has been
664 -- rewritten as a block, and the constraint check will be applied to the
665 -- assignment within the block.
667 elsif Is_Array_Type (T1)
669 (Nkind (Rhs) /= N_Type_Conversion
670 or else Is_Constrained (Etype (Rhs)))
672 (Nkind (Rhs) /= N_Function_Call
673 or else Nkind (N) /= N_Block_Statement)
675 -- Assignment verifies that the length of the Lsh and Rhs are equal,
676 -- but of course the indexes do not have to match. If the right-hand
677 -- side is a type conversion to an unconstrained type, a length check
678 -- is performed on the expression itself during expansion. In rare
679 -- cases, the redundant length check is computed on an index type
680 -- with a different representation, triggering incorrect code in the
683 Apply_Length_Check (Rhs, Etype (Lhs));
686 -- Discriminant checks are applied in the course of expansion
691 -- Note: modifications of the Lhs may only be recorded after
692 -- checks have been applied.
694 Note_Possible_Modification (Lhs, Sure => True);
695 Check_Order_Dependence;
697 -- ??? a real accessibility check is needed when ???
699 -- Post warning for redundant assignment or variable to itself
701 if Warn_On_Redundant_Constructs
703 -- We only warn for source constructs
705 and then Comes_From_Source (N)
707 -- Where the object is the same on both sides
709 and then Same_Object (Lhs, Original_Node (Rhs))
711 -- But exclude the case where the right side was an operation that
712 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
713 -- don't want to warn in such a case, since it is reasonable to write
714 -- such expressions especially when K is defined symbolically in some
717 and then Nkind (Original_Node (Rhs)) not in N_Op
719 if Nkind (Lhs) in N_Has_Entity then
720 Error_Msg_NE -- CODEFIX
721 ("?r?useless assignment of & to itself!", N, Entity (Lhs));
723 Error_Msg_N -- CODEFIX
724 ("?r?useless assignment of object to itself!", N);
728 -- Check for non-allowed composite assignment
730 if not Support_Composite_Assign_On_Target
731 and then (Is_Array_Type (T1) or else Is_Record_Type (T1))
732 and then (not Has_Size_Clause (T1) or else Esize (T1) > 64)
734 Error_Msg_CRT ("composite assignment", N);
737 -- Check elaboration warning for left side if not in elab code
739 if not In_Subprogram_Or_Concurrent_Unit then
740 Check_Elab_Assign (Lhs);
743 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
744 -- assignment is a source assignment in the extended main source unit.
745 -- We are not interested in any reference information outside this
746 -- context, or in compiler generated assignment statements.
748 if Comes_From_Source (N)
749 and then In_Extended_Main_Source_Unit (Lhs)
751 Set_Referenced_Modified (Lhs, Out_Param => False);
754 -- Final step. If left side is an entity, then we may be able to reset
755 -- the current tracked values to new safe values. We only have something
756 -- to do if the left side is an entity name, and expansion has not
757 -- modified the node into something other than an assignment, and of
758 -- course we only capture values if it is safe to do so.
760 if Is_Entity_Name (Lhs)
761 and then Nkind (N) = N_Assignment_Statement
764 Ent : constant Entity_Id := Entity (Lhs);
767 if Safe_To_Capture_Value (N, Ent) then
769 -- If simple variable on left side, warn if this assignment
770 -- blots out another one (rendering it useless). We only do
771 -- this for source assignments, otherwise we can generate bogus
772 -- warnings when an assignment is rewritten as another
773 -- assignment, and gets tied up with itself.
775 if Warn_On_Modified_Unread
776 and then Is_Assignable (Ent)
777 and then Comes_From_Source (N)
778 and then In_Extended_Main_Source_Unit (Ent)
780 Warn_On_Useless_Assignment (Ent, N);
783 -- If we are assigning an access type and the left side is an
784 -- entity, then make sure that the Is_Known_[Non_]Null flags
785 -- properly reflect the state of the entity after assignment.
787 if Is_Access_Type (T1) then
788 if Known_Non_Null (Rhs) then
789 Set_Is_Known_Non_Null (Ent, True);
791 elsif Known_Null (Rhs)
792 and then not Can_Never_Be_Null (Ent)
794 Set_Is_Known_Null (Ent, True);
797 Set_Is_Known_Null (Ent, False);
799 if not Can_Never_Be_Null (Ent) then
800 Set_Is_Known_Non_Null (Ent, False);
804 -- For discrete types, we may be able to set the current value
805 -- if the value is known at compile time.
807 elsif Is_Discrete_Type (T1)
808 and then Compile_Time_Known_Value (Rhs)
810 Set_Current_Value (Ent, Rhs);
812 Set_Current_Value (Ent, Empty);
815 -- If not safe to capture values, kill them
823 -- If assigning to an object in whole or in part, note location of
824 -- assignment in case no one references value. We only do this for
825 -- source assignments, otherwise we can generate bogus warnings when an
826 -- assignment is rewritten as another assignment, and gets tied up with
830 Ent : constant Entity_Id := Get_Enclosing_Object (Lhs);
833 and then Safe_To_Capture_Value (N, Ent)
834 and then Nkind (N) = N_Assignment_Statement
835 and then Warn_On_Modified_Unread
836 and then Is_Assignable (Ent)
837 and then Comes_From_Source (N)
838 and then In_Extended_Main_Source_Unit (Ent)
840 Set_Last_Assignment (Ent, Lhs);
844 Analyze_Dimension (N);
845 end Analyze_Assignment;
847 -----------------------------
848 -- Analyze_Block_Statement --
849 -----------------------------
851 procedure Analyze_Block_Statement (N : Node_Id) is
852 procedure Install_Return_Entities (Scop : Entity_Id);
853 -- Install all entities of return statement scope Scop in the visibility
854 -- chain except for the return object since its entity is reused in a
857 -----------------------------
858 -- Install_Return_Entities --
859 -----------------------------
861 procedure Install_Return_Entities (Scop : Entity_Id) is
865 Id := First_Entity (Scop);
866 while Present (Id) loop
868 -- Do not install the return object
870 if not Ekind_In (Id, E_Constant, E_Variable)
871 or else not Is_Return_Object (Id)
878 end Install_Return_Entities;
880 -- Local constants and variables
882 Decls : constant List_Id := Declarations (N);
883 Id : constant Node_Id := Identifier (N);
884 HSS : constant Node_Id := Handled_Statement_Sequence (N);
886 Is_BIP_Return_Statement : Boolean;
888 -- Start of processing for Analyze_Block_Statement
891 -- In SPARK mode, we reject block statements. Note that the case of
892 -- block statements generated by the expander is fine.
894 if Nkind (Original_Node (N)) = N_Block_Statement then
895 Check_SPARK_Restriction ("block statement is not allowed", N);
898 -- If no handled statement sequence is present, things are really messed
899 -- up, and we just return immediately (defence against previous errors).
902 Check_Error_Detected;
906 -- Detect whether the block is actually a rewritten return statement of
907 -- a build-in-place function.
909 Is_BIP_Return_Statement :=
911 and then Present (Entity (Id))
912 and then Ekind (Entity (Id)) = E_Return_Statement
913 and then Is_Build_In_Place_Function
914 (Return_Applies_To (Entity (Id)));
916 -- Normal processing with HSS present
919 EH : constant List_Id := Exception_Handlers (HSS);
920 Ent : Entity_Id := Empty;
923 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
924 -- Recursively save value of this global, will be restored on exit
927 -- Initialize unblocked exit count for statements of begin block
928 -- plus one for each exception handler that is present.
930 Unblocked_Exit_Count := 1;
933 Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH);
936 -- If a label is present analyze it and mark it as referenced
942 -- An error defense. If we have an identifier, but no entity, then
943 -- something is wrong. If previous errors, then just remove the
944 -- identifier and continue, otherwise raise an exception.
947 Check_Error_Detected;
948 Set_Identifier (N, Empty);
951 Set_Ekind (Ent, E_Block);
952 Generate_Reference (Ent, N, ' ');
953 Generate_Definition (Ent);
955 if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
956 Set_Label_Construct (Parent (Ent), N);
961 -- If no entity set, create a label entity
964 Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B');
965 Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N)));
969 Set_Etype (Ent, Standard_Void_Type);
970 Set_Block_Node (Ent, Identifier (N));
973 -- The block served as an extended return statement. Ensure that any
974 -- entities created during the analysis and expansion of the return
975 -- object declaration are once again visible.
977 if Is_BIP_Return_Statement then
978 Install_Return_Entities (Ent);
981 if Present (Decls) then
982 Analyze_Declarations (Decls);
984 Inspect_Deferred_Constant_Completion (Decls);
988 Process_End_Label (HSS, 'e', Ent);
990 -- If exception handlers are present, then we indicate that enclosing
991 -- scopes contain a block with handlers. We only need to mark non-
997 Set_Has_Nested_Block_With_Handler (S);
998 exit when Is_Overloadable (S)
999 or else Ekind (S) = E_Package
1000 or else Is_Generic_Unit (S);
1005 Check_References (Ent);
1006 Warn_On_Useless_Assignments (Ent);
1009 if Unblocked_Exit_Count = 0 then
1010 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1011 Check_Unreachable_Code (N);
1013 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1016 end Analyze_Block_Statement;
1018 ----------------------------
1019 -- Analyze_Case_Statement --
1020 ----------------------------
1022 procedure Analyze_Case_Statement (N : Node_Id) is
1024 Exp_Type : Entity_Id;
1025 Exp_Btype : Entity_Id;
1027 Dont_Care : Boolean;
1028 Others_Present : Boolean;
1030 pragma Warnings (Off, Last_Choice);
1031 pragma Warnings (Off, Dont_Care);
1032 -- Don't care about assigned values
1034 Statements_Analyzed : Boolean := False;
1035 -- Set True if at least some statement sequences get analyzed. If False
1036 -- on exit, means we had a serious error that prevented full analysis of
1037 -- the case statement, and as a result it is not a good idea to output
1038 -- warning messages about unreachable code.
1040 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
1041 -- Recursively save value of this global, will be restored on exit
1043 procedure Non_Static_Choice_Error (Choice : Node_Id);
1044 -- Error routine invoked by the generic instantiation below when the
1045 -- case statement has a non static choice.
1047 procedure Process_Statements (Alternative : Node_Id);
1048 -- Analyzes all the statements associated with a case alternative.
1049 -- Needed by the generic instantiation below.
1051 package Case_Choices_Processing is new
1052 Generic_Choices_Processing
1053 (Get_Alternatives => Alternatives,
1054 Get_Choices => Discrete_Choices,
1055 Process_Empty_Choice => No_OP,
1056 Process_Non_Static_Choice => Non_Static_Choice_Error,
1057 Process_Associated_Node => Process_Statements);
1058 use Case_Choices_Processing;
1059 -- Instantiation of the generic choice processing package
1061 -----------------------------
1062 -- Non_Static_Choice_Error --
1063 -----------------------------
1065 procedure Non_Static_Choice_Error (Choice : Node_Id) is
1067 Flag_Non_Static_Expr
1068 ("choice given in case statement is not static!", Choice);
1069 end Non_Static_Choice_Error;
1071 ------------------------
1072 -- Process_Statements --
1073 ------------------------
1075 procedure Process_Statements (Alternative : Node_Id) is
1076 Choices : constant List_Id := Discrete_Choices (Alternative);
1080 Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
1081 Statements_Analyzed := True;
1083 -- An interesting optimization. If the case statement expression
1084 -- is a simple entity, then we can set the current value within an
1085 -- alternative if the alternative has one possible value.
1089 -- when 2 | 3 => beta
1090 -- when others => gamma
1092 -- Here we know that N is initially 1 within alpha, but for beta and
1093 -- gamma, we do not know anything more about the initial value.
1095 if Is_Entity_Name (Exp) then
1096 Ent := Entity (Exp);
1098 if Ekind_In (Ent, E_Variable,
1102 if List_Length (Choices) = 1
1103 and then Nkind (First (Choices)) in N_Subexpr
1104 and then Compile_Time_Known_Value (First (Choices))
1106 Set_Current_Value (Entity (Exp), First (Choices));
1109 Analyze_Statements (Statements (Alternative));
1111 -- After analyzing the case, set the current value to empty
1112 -- since we won't know what it is for the next alternative
1113 -- (unless reset by this same circuit), or after the case.
1115 Set_Current_Value (Entity (Exp), Empty);
1120 -- Case where expression is not an entity name of a variable
1122 Analyze_Statements (Statements (Alternative));
1123 end Process_Statements;
1125 -- Start of processing for Analyze_Case_Statement
1128 Unblocked_Exit_Count := 0;
1129 Exp := Expression (N);
1132 -- The expression must be of any discrete type. In rare cases, the
1133 -- expander constructs a case statement whose expression has a private
1134 -- type whose full view is discrete. This can happen when generating
1135 -- a stream operation for a variant type after the type is frozen,
1136 -- when the partial of view of the type of the discriminant is private.
1137 -- In that case, use the full view to analyze case alternatives.
1139 if not Is_Overloaded (Exp)
1140 and then not Comes_From_Source (N)
1141 and then Is_Private_Type (Etype (Exp))
1142 and then Present (Full_View (Etype (Exp)))
1143 and then Is_Discrete_Type (Full_View (Etype (Exp)))
1145 Resolve (Exp, Etype (Exp));
1146 Exp_Type := Full_View (Etype (Exp));
1149 Analyze_And_Resolve (Exp, Any_Discrete);
1150 Exp_Type := Etype (Exp);
1153 Check_Unset_Reference (Exp);
1154 Exp_Btype := Base_Type (Exp_Type);
1156 -- The expression must be of a discrete type which must be determinable
1157 -- independently of the context in which the expression occurs, but
1158 -- using the fact that the expression must be of a discrete type.
1159 -- Moreover, the type this expression must not be a character literal
1160 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1162 -- If error already reported by Resolve, nothing more to do
1164 if Exp_Btype = Any_Discrete
1165 or else Exp_Btype = Any_Type
1169 elsif Exp_Btype = Any_Character then
1171 ("character literal as case expression is ambiguous", Exp);
1174 elsif Ada_Version = Ada_83
1175 and then (Is_Generic_Type (Exp_Btype)
1176 or else Is_Generic_Type (Root_Type (Exp_Btype)))
1179 ("(Ada 83) case expression cannot be of a generic type", Exp);
1183 -- If the case expression is a formal object of mode in out, then treat
1184 -- it as having a nonstatic subtype by forcing use of the base type
1185 -- (which has to get passed to Check_Case_Choices below). Also use base
1186 -- type when the case expression is parenthesized.
1188 if Paren_Count (Exp) > 0
1189 or else (Is_Entity_Name (Exp)
1190 and then Ekind (Entity (Exp)) = E_Generic_In_Out_Parameter)
1192 Exp_Type := Exp_Btype;
1195 -- Call instantiated Analyze_Choices which does the rest of the work
1197 Analyze_Choices (N, Exp_Type, Dont_Care, Others_Present);
1199 -- A case statement with a single OTHERS alternative is not allowed
1203 and then List_Length (Alternatives (N)) = 1
1205 Check_SPARK_Restriction
1206 ("OTHERS as unique case alternative is not allowed", N);
1209 if Exp_Type = Universal_Integer and then not Others_Present then
1210 Error_Msg_N ("case on universal integer requires OTHERS choice", Exp);
1213 -- If all our exits were blocked by unconditional transfers of control,
1214 -- then the entire CASE statement acts as an unconditional transfer of
1215 -- control, so treat it like one, and check unreachable code. Skip this
1216 -- test if we had serious errors preventing any statement analysis.
1218 if Unblocked_Exit_Count = 0 and then Statements_Analyzed then
1219 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1220 Check_Unreachable_Code (N);
1222 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1225 if not Expander_Active
1226 and then Compile_Time_Known_Value (Expression (N))
1227 and then Serious_Errors_Detected = 0
1230 Chosen : constant Node_Id := Find_Static_Alternative (N);
1234 Alt := First (Alternatives (N));
1235 while Present (Alt) loop
1236 if Alt /= Chosen then
1237 Remove_Warning_Messages (Statements (Alt));
1244 end Analyze_Case_Statement;
1246 ----------------------------
1247 -- Analyze_Exit_Statement --
1248 ----------------------------
1250 -- If the exit includes a name, it must be the name of a currently open
1251 -- loop. Otherwise there must be an innermost open loop on the stack, to
1252 -- which the statement implicitly refers.
1254 -- Additionally, in SPARK mode:
1256 -- The exit can only name the closest enclosing loop;
1258 -- An exit with a when clause must be directly contained in a loop;
1260 -- An exit without a when clause must be directly contained in an
1261 -- if-statement with no elsif or else, which is itself directly contained
1262 -- in a loop. The exit must be the last statement in the if-statement.
1264 procedure Analyze_Exit_Statement (N : Node_Id) is
1265 Target : constant Node_Id := Name (N);
1266 Cond : constant Node_Id := Condition (N);
1267 Scope_Id : Entity_Id;
1273 Check_Unreachable_Code (N);
1276 if Present (Target) then
1278 U_Name := Entity (Target);
1280 if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then
1281 Error_Msg_N ("invalid loop name in exit statement", N);
1285 if Has_Loop_In_Inner_Open_Scopes (U_Name) then
1286 Check_SPARK_Restriction
1287 ("exit label must name the closest enclosing loop", N);
1290 Set_Has_Exit (U_Name);
1297 for J in reverse 0 .. Scope_Stack.Last loop
1298 Scope_Id := Scope_Stack.Table (J).Entity;
1299 Kind := Ekind (Scope_Id);
1302 and then (No (Target) or else Scope_Id = U_Name)
1304 Set_Has_Exit (Scope_Id);
1307 elsif Kind = E_Block
1308 or else Kind = E_Loop
1309 or else Kind = E_Return_Statement
1315 ("cannot exit from program unit or accept statement", N);
1320 -- Verify that if present the condition is a Boolean expression
1322 if Present (Cond) then
1323 Analyze_And_Resolve (Cond, Any_Boolean);
1324 Check_Unset_Reference (Cond);
1327 -- In SPARK mode, verify that the exit statement respects the SPARK
1330 if Present (Cond) then
1331 if Nkind (Parent (N)) /= N_Loop_Statement then
1332 Check_SPARK_Restriction
1333 ("exit with when clause must be directly in loop", N);
1337 if Nkind (Parent (N)) /= N_If_Statement then
1338 if Nkind (Parent (N)) = N_Elsif_Part then
1339 Check_SPARK_Restriction
1340 ("exit must be in IF without ELSIF", N);
1342 Check_SPARK_Restriction ("exit must be directly in IF", N);
1345 elsif Nkind (Parent (Parent (N))) /= N_Loop_Statement then
1346 Check_SPARK_Restriction
1347 ("exit must be in IF directly in loop", N);
1349 -- First test the presence of ELSE, so that an exit in an ELSE leads
1350 -- to an error mentioning the ELSE.
1352 elsif Present (Else_Statements (Parent (N))) then
1353 Check_SPARK_Restriction ("exit must be in IF without ELSE", N);
1355 -- An exit in an ELSIF does not reach here, as it would have been
1356 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1358 elsif Present (Elsif_Parts (Parent (N))) then
1359 Check_SPARK_Restriction ("exit must be in IF without ELSIF", N);
1363 -- Chain exit statement to associated loop entity
1365 Set_Next_Exit_Statement (N, First_Exit_Statement (Scope_Id));
1366 Set_First_Exit_Statement (Scope_Id, N);
1368 -- Since the exit may take us out of a loop, any previous assignment
1369 -- statement is not useless, so clear last assignment indications. It
1370 -- is OK to keep other current values, since if the exit statement
1371 -- does not exit, then the current values are still valid.
1373 Kill_Current_Values (Last_Assignment_Only => True);
1374 end Analyze_Exit_Statement;
1376 ----------------------------
1377 -- Analyze_Goto_Statement --
1378 ----------------------------
1380 procedure Analyze_Goto_Statement (N : Node_Id) is
1381 Label : constant Node_Id := Name (N);
1382 Scope_Id : Entity_Id;
1383 Label_Scope : Entity_Id;
1384 Label_Ent : Entity_Id;
1387 Check_SPARK_Restriction ("goto statement is not allowed", N);
1389 -- Actual semantic checks
1391 Check_Unreachable_Code (N);
1392 Kill_Current_Values (Last_Assignment_Only => True);
1395 Label_Ent := Entity (Label);
1397 -- Ignore previous error
1399 if Label_Ent = Any_Id then
1400 Check_Error_Detected;
1403 -- We just have a label as the target of a goto
1405 elsif Ekind (Label_Ent) /= E_Label then
1406 Error_Msg_N ("target of goto statement must be a label", Label);
1409 -- Check that the target of the goto is reachable according to Ada
1410 -- scoping rules. Note: the special gotos we generate for optimizing
1411 -- local handling of exceptions would violate these rules, but we mark
1412 -- such gotos as analyzed when built, so this code is never entered.
1414 elsif not Reachable (Label_Ent) then
1415 Error_Msg_N ("target of goto statement is not reachable", Label);
1419 -- Here if goto passes initial validity checks
1421 Label_Scope := Enclosing_Scope (Label_Ent);
1423 for J in reverse 0 .. Scope_Stack.Last loop
1424 Scope_Id := Scope_Stack.Table (J).Entity;
1426 if Label_Scope = Scope_Id
1427 or else (Ekind (Scope_Id) /= E_Block
1428 and then Ekind (Scope_Id) /= E_Loop
1429 and then Ekind (Scope_Id) /= E_Return_Statement)
1431 if Scope_Id /= Label_Scope then
1433 ("cannot exit from program unit or accept statement", N);
1440 raise Program_Error;
1441 end Analyze_Goto_Statement;
1443 --------------------------
1444 -- Analyze_If_Statement --
1445 --------------------------
1447 -- A special complication arises in the analysis of if statements
1449 -- The expander has circuitry to completely delete code that it can tell
1450 -- will not be executed (as a result of compile time known conditions). In
1451 -- the analyzer, we ensure that code that will be deleted in this manner is
1452 -- analyzed but not expanded. This is obviously more efficient, but more
1453 -- significantly, difficulties arise if code is expanded and then
1454 -- eliminated (e.g. exception table entries disappear). Similarly, itypes
1455 -- generated in deleted code must be frozen from start, because the nodes
1456 -- on which they depend will not be available at the freeze point.
1458 procedure Analyze_If_Statement (N : Node_Id) is
1461 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
1462 -- Recursively save value of this global, will be restored on exit
1464 Save_In_Deleted_Code : Boolean;
1466 Del : Boolean := False;
1467 -- This flag gets set True if a True condition has been found, which
1468 -- means that remaining ELSE/ELSIF parts are deleted.
1470 procedure Analyze_Cond_Then (Cnode : Node_Id);
1471 -- This is applied to either the N_If_Statement node itself or to an
1472 -- N_Elsif_Part node. It deals with analyzing the condition and the THEN
1473 -- statements associated with it.
1475 -----------------------
1476 -- Analyze_Cond_Then --
1477 -----------------------
1479 procedure Analyze_Cond_Then (Cnode : Node_Id) is
1480 Cond : constant Node_Id := Condition (Cnode);
1481 Tstm : constant List_Id := Then_Statements (Cnode);
1484 Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
1485 Analyze_And_Resolve (Cond, Any_Boolean);
1486 Check_Unset_Reference (Cond);
1487 Set_Current_Value_Condition (Cnode);
1489 -- If already deleting, then just analyze then statements
1492 Analyze_Statements (Tstm);
1494 -- Compile time known value, not deleting yet
1496 elsif Compile_Time_Known_Value (Cond) then
1497 Save_In_Deleted_Code := In_Deleted_Code;
1499 -- If condition is True, then analyze the THEN statements and set
1500 -- no expansion for ELSE and ELSIF parts.
1502 if Is_True (Expr_Value (Cond)) then
1503 Analyze_Statements (Tstm);
1505 Expander_Mode_Save_And_Set (False);
1506 In_Deleted_Code := True;
1508 -- If condition is False, analyze THEN with expansion off
1510 else -- Is_False (Expr_Value (Cond))
1511 Expander_Mode_Save_And_Set (False);
1512 In_Deleted_Code := True;
1513 Analyze_Statements (Tstm);
1514 Expander_Mode_Restore;
1515 In_Deleted_Code := Save_In_Deleted_Code;
1518 -- Not known at compile time, not deleting, normal analysis
1521 Analyze_Statements (Tstm);
1523 end Analyze_Cond_Then;
1525 -- Start of Analyze_If_Statement
1528 -- Initialize exit count for else statements. If there is no else part,
1529 -- this count will stay non-zero reflecting the fact that the uncovered
1530 -- else case is an unblocked exit.
1532 Unblocked_Exit_Count := 1;
1533 Analyze_Cond_Then (N);
1535 -- Now to analyze the elsif parts if any are present
1537 if Present (Elsif_Parts (N)) then
1538 E := First (Elsif_Parts (N));
1539 while Present (E) loop
1540 Analyze_Cond_Then (E);
1545 if Present (Else_Statements (N)) then
1546 Analyze_Statements (Else_Statements (N));
1549 -- If all our exits were blocked by unconditional transfers of control,
1550 -- then the entire IF statement acts as an unconditional transfer of
1551 -- control, so treat it like one, and check unreachable code.
1553 if Unblocked_Exit_Count = 0 then
1554 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1555 Check_Unreachable_Code (N);
1557 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1561 Expander_Mode_Restore;
1562 In_Deleted_Code := Save_In_Deleted_Code;
1565 if not Expander_Active
1566 and then Compile_Time_Known_Value (Condition (N))
1567 and then Serious_Errors_Detected = 0
1569 if Is_True (Expr_Value (Condition (N))) then
1570 Remove_Warning_Messages (Else_Statements (N));
1572 if Present (Elsif_Parts (N)) then
1573 E := First (Elsif_Parts (N));
1574 while Present (E) loop
1575 Remove_Warning_Messages (Then_Statements (E));
1581 Remove_Warning_Messages (Then_Statements (N));
1584 end Analyze_If_Statement;
1586 ----------------------------------------
1587 -- Analyze_Implicit_Label_Declaration --
1588 ----------------------------------------
1590 -- An implicit label declaration is generated in the innermost enclosing
1591 -- declarative part. This is done for labels, and block and loop names.
1593 -- Note: any changes in this routine may need to be reflected in
1594 -- Analyze_Label_Entity.
1596 procedure Analyze_Implicit_Label_Declaration (N : Node_Id) is
1597 Id : constant Node_Id := Defining_Identifier (N);
1600 Set_Ekind (Id, E_Label);
1601 Set_Etype (Id, Standard_Void_Type);
1602 Set_Enclosing_Scope (Id, Current_Scope);
1603 end Analyze_Implicit_Label_Declaration;
1605 ------------------------------
1606 -- Analyze_Iteration_Scheme --
1607 ------------------------------
1609 procedure Analyze_Iteration_Scheme (N : Node_Id) is
1611 Iter_Spec : Node_Id;
1612 Loop_Spec : Node_Id;
1615 -- For an infinite loop, there is no iteration scheme
1621 Cond := Condition (N);
1622 Iter_Spec := Iterator_Specification (N);
1623 Loop_Spec := Loop_Parameter_Specification (N);
1625 if Present (Cond) then
1626 Analyze_And_Resolve (Cond, Any_Boolean);
1627 Check_Unset_Reference (Cond);
1628 Set_Current_Value_Condition (N);
1630 elsif Present (Iter_Spec) then
1631 Analyze_Iterator_Specification (Iter_Spec);
1634 Analyze_Loop_Parameter_Specification (Loop_Spec);
1636 end Analyze_Iteration_Scheme;
1638 ------------------------------------
1639 -- Analyze_Iterator_Specification --
1640 ------------------------------------
1642 procedure Analyze_Iterator_Specification (N : Node_Id) is
1643 Loc : constant Source_Ptr := Sloc (N);
1644 Def_Id : constant Node_Id := Defining_Identifier (N);
1645 Subt : constant Node_Id := Subtype_Indication (N);
1646 Iter_Name : constant Node_Id := Name (N);
1652 Enter_Name (Def_Id);
1654 if Present (Subt) then
1658 Preanalyze_Range (Iter_Name);
1660 -- Set the kind of the loop variable, which is not visible within
1661 -- the iterator name.
1663 Set_Ekind (Def_Id, E_Variable);
1665 -- If the domain of iteration is an expression, create a declaration for
1666 -- it, so that finalization actions are introduced outside of the loop.
1667 -- The declaration must be a renaming because the body of the loop may
1668 -- assign to elements.
1670 if not Is_Entity_Name (Iter_Name)
1672 -- When the context is a quantified expression, the renaming
1673 -- declaration is delayed until the expansion phase if we are
1676 and then (Nkind (Parent (N)) /= N_Quantified_Expression
1677 or else Operating_Mode = Check_Semantics)
1679 -- Do not perform this expansion in Alfa mode, since the formal
1680 -- verification directly deals with the source form of the iterator.
1682 and then not Alfa_Mode
1685 Id : constant Entity_Id := Make_Temporary (Loc, 'R', Iter_Name);
1689 Typ := Etype (Iter_Name);
1691 -- Protect against malformed iterator
1693 if Typ = Any_Type then
1694 Error_Msg_N ("invalid expression in loop iterator", Iter_Name);
1698 -- The name in the renaming declaration may be a function call.
1699 -- Indicate that it does not come from source, to suppress
1700 -- spurious warnings on renamings of parameterless functions,
1701 -- a common enough idiom in user-defined iterators.
1704 Make_Object_Renaming_Declaration (Loc,
1705 Defining_Identifier => Id,
1706 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
1708 New_Copy_Tree (Iter_Name, New_Sloc => Loc));
1710 Insert_Actions (Parent (Parent (N)), New_List (Decl));
1711 Rewrite (Name (N), New_Occurrence_Of (Id, Loc));
1712 Set_Etype (Id, Typ);
1713 Set_Etype (Name (N), Typ);
1716 -- Container is an entity or an array with uncontrolled components, or
1717 -- else it is a container iterator given by a function call, typically
1718 -- called Iterate in the case of predefined containers, even though
1719 -- Iterate is not a reserved name. What matters is that the return type
1720 -- of the function is an iterator type.
1722 elsif Is_Entity_Name (Iter_Name) then
1723 Analyze (Iter_Name);
1725 if Nkind (Iter_Name) = N_Function_Call then
1727 C : constant Node_Id := Name (Iter_Name);
1732 if not Is_Overloaded (Iter_Name) then
1733 Resolve (Iter_Name, Etype (C));
1736 Get_First_Interp (C, I, It);
1737 while It.Typ /= Empty loop
1738 if Reverse_Present (N) then
1739 if Is_Reversible_Iterator (It.Typ) then
1740 Resolve (Iter_Name, It.Typ);
1744 elsif Is_Iterator (It.Typ) then
1745 Resolve (Iter_Name, It.Typ);
1749 Get_Next_Interp (I, It);
1754 -- Domain of iteration is not overloaded
1757 Resolve (Iter_Name, Etype (Iter_Name));
1761 Typ := Etype (Iter_Name);
1763 if Is_Array_Type (Typ) then
1764 if Of_Present (N) then
1765 Set_Etype (Def_Id, Component_Type (Typ));
1767 -- Here we have a missing Range attribute
1771 ("missing Range attribute in iteration over an array", N);
1773 -- In Ada 2012 mode, this may be an attempt at an iterator
1775 if Ada_Version >= Ada_2012 then
1777 ("\if& is meant to designate an element of the array, use OF",
1781 -- Prevent cascaded errors
1783 Set_Ekind (Def_Id, E_Loop_Parameter);
1784 Set_Etype (Def_Id, Etype (First_Index (Typ)));
1787 -- Check for type error in iterator
1789 elsif Typ = Any_Type then
1792 -- Iteration over a container
1795 Set_Ekind (Def_Id, E_Loop_Parameter);
1797 if Of_Present (N) then
1799 -- The type of the loop variable is the Iterator_Element aspect of
1800 -- the container type.
1803 Element : constant Entity_Id :=
1804 Find_Aspect (Typ, Aspect_Iterator_Element);
1806 if No (Element) then
1807 Error_Msg_NE ("cannot iterate over&", N, Typ);
1810 Set_Etype (Def_Id, Entity (Element));
1812 -- If the container has a variable indexing aspect, the
1813 -- element is a variable and is modifiable in the loop.
1815 if Present (Find_Aspect (Typ, Aspect_Variable_Indexing)) then
1816 Set_Ekind (Def_Id, E_Variable);
1822 -- For an iteration of the form IN, the name must denote an
1823 -- iterator, typically the result of a call to Iterate. Give a
1824 -- useful error message when the name is a container by itself.
1826 if Is_Entity_Name (Original_Node (Name (N)))
1827 and then not Is_Iterator (Typ)
1829 if No (Find_Aspect (Typ, Aspect_Iterator_Element)) then
1831 ("cannot iterate over&", Name (N), Typ);
1834 ("name must be an iterator, not a container", Name (N));
1838 ("\to iterate directly over the elements of a container, " &
1839 "write `of &`", Name (N), Original_Node (Name (N)));
1842 -- The result type of Iterate function is the classwide type of
1843 -- the interface parent. We need the specific Cursor type defined
1844 -- in the container package.
1846 Ent := First_Entity (Scope (Typ));
1847 while Present (Ent) loop
1848 if Chars (Ent) = Name_Cursor then
1849 Set_Etype (Def_Id, Etype (Ent));
1857 end Analyze_Iterator_Specification;
1863 -- Note: the semantic work required for analyzing labels (setting them as
1864 -- reachable) was done in a prepass through the statements in the block,
1865 -- so that forward gotos would be properly handled. See Analyze_Statements
1866 -- for further details. The only processing required here is to deal with
1867 -- optimizations that depend on an assumption of sequential control flow,
1868 -- since of course the occurrence of a label breaks this assumption.
1870 procedure Analyze_Label (N : Node_Id) is
1871 pragma Warnings (Off, N);
1873 Kill_Current_Values;
1876 --------------------------
1877 -- Analyze_Label_Entity --
1878 --------------------------
1880 procedure Analyze_Label_Entity (E : Entity_Id) is
1882 Set_Ekind (E, E_Label);
1883 Set_Etype (E, Standard_Void_Type);
1884 Set_Enclosing_Scope (E, Current_Scope);
1885 Set_Reachable (E, True);
1886 end Analyze_Label_Entity;
1888 ------------------------------------------
1889 -- Analyze_Loop_Parameter_Specification --
1890 ------------------------------------------
1892 procedure Analyze_Loop_Parameter_Specification (N : Node_Id) is
1893 Loop_Nod : constant Node_Id := Parent (Parent (N));
1895 procedure Check_Controlled_Array_Attribute (DS : Node_Id);
1896 -- If the bounds are given by a 'Range reference on a function call
1897 -- that returns a controlled array, introduce an explicit declaration
1898 -- to capture the bounds, so that the function result can be finalized
1899 -- in timely fashion.
1901 function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean;
1902 -- N is the node for an arbitrary construct. This function searches the
1903 -- construct N to see if any expressions within it contain function
1904 -- calls that use the secondary stack, returning True if any such call
1905 -- is found, and False otherwise.
1907 procedure Process_Bounds (R : Node_Id);
1908 -- If the iteration is given by a range, create temporaries and
1909 -- assignment statements block to capture the bounds and perform
1910 -- required finalization actions in case a bound includes a function
1911 -- call that uses the temporary stack. We first pre-analyze a copy of
1912 -- the range in order to determine the expected type, and analyze and
1913 -- resolve the original bounds.
1915 --------------------------------------
1916 -- Check_Controlled_Array_Attribute --
1917 --------------------------------------
1919 procedure Check_Controlled_Array_Attribute (DS : Node_Id) is
1921 if Nkind (DS) = N_Attribute_Reference
1922 and then Is_Entity_Name (Prefix (DS))
1923 and then Ekind (Entity (Prefix (DS))) = E_Function
1924 and then Is_Array_Type (Etype (Entity (Prefix (DS))))
1926 Is_Controlled (Component_Type (Etype (Entity (Prefix (DS)))))
1927 and then Expander_Active
1930 Loc : constant Source_Ptr := Sloc (N);
1931 Arr : constant Entity_Id := Etype (Entity (Prefix (DS)));
1932 Indx : constant Entity_Id :=
1933 Base_Type (Etype (First_Index (Arr)));
1934 Subt : constant Entity_Id := Make_Temporary (Loc, 'S');
1939 Make_Subtype_Declaration (Loc,
1940 Defining_Identifier => Subt,
1941 Subtype_Indication =>
1942 Make_Subtype_Indication (Loc,
1943 Subtype_Mark => New_Reference_To (Indx, Loc),
1945 Make_Range_Constraint (Loc, Relocate_Node (DS))));
1946 Insert_Before (Loop_Nod, Decl);
1950 Make_Attribute_Reference (Loc,
1951 Prefix => New_Reference_To (Subt, Loc),
1952 Attribute_Name => Attribute_Name (DS)));
1957 end Check_Controlled_Array_Attribute;
1959 ------------------------------------
1960 -- Has_Call_Using_Secondary_Stack --
1961 ------------------------------------
1963 function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean is
1965 function Check_Call (N : Node_Id) return Traverse_Result;
1966 -- Check if N is a function call which uses the secondary stack
1972 function Check_Call (N : Node_Id) return Traverse_Result is
1975 Return_Typ : Entity_Id;
1978 if Nkind (N) = N_Function_Call then
1981 -- Call using access to subprogram with explicit dereference
1983 if Nkind (Nam) = N_Explicit_Dereference then
1984 Subp := Etype (Nam);
1986 -- Call using a selected component notation or Ada 2005 object
1987 -- operation notation
1989 elsif Nkind (Nam) = N_Selected_Component then
1990 Subp := Entity (Selector_Name (Nam));
1995 Subp := Entity (Nam);
1998 Return_Typ := Etype (Subp);
2000 if Is_Composite_Type (Return_Typ)
2001 and then not Is_Constrained (Return_Typ)
2005 elsif Sec_Stack_Needed_For_Return (Subp) then
2010 -- Continue traversing the tree
2015 function Check_Calls is new Traverse_Func (Check_Call);
2017 -- Start of processing for Has_Call_Using_Secondary_Stack
2020 return Check_Calls (N) = Abandon;
2021 end Has_Call_Using_Secondary_Stack;
2023 --------------------
2024 -- Process_Bounds --
2025 --------------------
2027 procedure Process_Bounds (R : Node_Id) is
2028 Loc : constant Source_Ptr := Sloc (N);
2031 (Original_Bound : Node_Id;
2032 Analyzed_Bound : Node_Id;
2033 Typ : Entity_Id) return Node_Id;
2034 -- Capture value of bound and return captured value
2041 (Original_Bound : Node_Id;
2042 Analyzed_Bound : Node_Id;
2043 Typ : Entity_Id) return Node_Id
2050 -- If the bound is a constant or an object, no need for a separate
2051 -- declaration. If the bound is the result of previous expansion
2052 -- it is already analyzed and should not be modified. Note that
2053 -- the Bound will be resolved later, if needed, as part of the
2054 -- call to Make_Index (literal bounds may need to be resolved to
2057 if Analyzed (Original_Bound) then
2058 return Original_Bound;
2060 elsif Nkind_In (Analyzed_Bound, N_Integer_Literal,
2061 N_Character_Literal)
2062 or else Is_Entity_Name (Analyzed_Bound)
2064 Analyze_And_Resolve (Original_Bound, Typ);
2065 return Original_Bound;
2068 -- Normally, the best approach is simply to generate a constant
2069 -- declaration that captures the bound. However, there is a nasty
2070 -- case where this is wrong. If the bound is complex, and has a
2071 -- possible use of the secondary stack, we need to generate a
2072 -- separate assignment statement to ensure the creation of a block
2073 -- which will release the secondary stack.
2075 -- We prefer the constant declaration, since it leaves us with a
2076 -- proper trace of the value, useful in optimizations that get rid
2077 -- of junk range checks.
2079 if not Has_Call_Using_Secondary_Stack (Analyzed_Bound) then
2080 Analyze_And_Resolve (Original_Bound, Typ);
2081 Force_Evaluation (Original_Bound);
2082 return Original_Bound;
2085 Id := Make_Temporary (Loc, 'R', Original_Bound);
2087 -- Here we make a declaration with a separate assignment
2088 -- statement, and insert before loop header.
2091 Make_Object_Declaration (Loc,
2092 Defining_Identifier => Id,
2093 Object_Definition => New_Occurrence_Of (Typ, Loc));
2096 Make_Assignment_Statement (Loc,
2097 Name => New_Occurrence_Of (Id, Loc),
2098 Expression => Relocate_Node (Original_Bound));
2100 Insert_Actions (Loop_Nod, New_List (Decl, Assign));
2102 -- Now that this temporary variable is initialized we decorate it
2103 -- as safe-to-reevaluate to inform to the backend that no further
2104 -- asignment will be issued and hence it can be handled as side
2105 -- effect free. Note that this decoration must be done when the
2106 -- assignment has been analyzed because otherwise it will be
2107 -- rejected (see Analyze_Assignment).
2109 Set_Is_Safe_To_Reevaluate (Id);
2111 Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc));
2113 if Nkind (Assign) = N_Assignment_Statement then
2114 return Expression (Assign);
2116 return Original_Bound;
2120 Hi : constant Node_Id := High_Bound (R);
2121 Lo : constant Node_Id := Low_Bound (R);
2122 R_Copy : constant Node_Id := New_Copy_Tree (R);
2127 -- Start of processing for Process_Bounds
2130 Set_Parent (R_Copy, Parent (R));
2131 Preanalyze_Range (R_Copy);
2132 Typ := Etype (R_Copy);
2134 -- If the type of the discrete range is Universal_Integer, then the
2135 -- bound's type must be resolved to Integer, and any object used to
2136 -- hold the bound must also have type Integer, unless the literal
2137 -- bounds are constant-folded expressions with a user-defined type.
2139 if Typ = Universal_Integer then
2140 if Nkind (Lo) = N_Integer_Literal
2141 and then Present (Etype (Lo))
2142 and then Scope (Etype (Lo)) /= Standard_Standard
2146 elsif Nkind (Hi) = N_Integer_Literal
2147 and then Present (Etype (Hi))
2148 and then Scope (Etype (Hi)) /= Standard_Standard
2153 Typ := Standard_Integer;
2159 New_Lo := One_Bound (Lo, Low_Bound (R_Copy), Typ);
2160 New_Hi := One_Bound (Hi, High_Bound (R_Copy), Typ);
2162 -- Propagate staticness to loop range itself, in case the
2163 -- corresponding subtype is static.
2166 and then Is_Static_Expression (New_Lo)
2168 Rewrite (Low_Bound (R), New_Copy (New_Lo));
2172 and then Is_Static_Expression (New_Hi)
2174 Rewrite (High_Bound (R), New_Copy (New_Hi));
2180 DS : constant Node_Id := Discrete_Subtype_Definition (N);
2181 Id : constant Entity_Id := Defining_Identifier (N);
2185 -- Start of processing for Analyze_Loop_Parameter_Specification
2190 -- We always consider the loop variable to be referenced, since the loop
2191 -- may be used just for counting purposes.
2193 Generate_Reference (Id, N, ' ');
2195 -- Check for the case of loop variable hiding a local variable (used
2196 -- later on to give a nice warning if the hidden variable is never
2200 H : constant Entity_Id := Homonym (Id);
2203 and then Ekind (H) = E_Variable
2204 and then Is_Discrete_Type (Etype (H))
2205 and then Enclosing_Dynamic_Scope (H) = Enclosing_Dynamic_Scope (Id)
2207 Set_Hiding_Loop_Variable (H, Id);
2211 -- Loop parameter specification must include subtype mark in SPARK
2213 if Nkind (DS) = N_Range then
2214 Check_SPARK_Restriction
2215 ("loop parameter specification must include subtype mark", N);
2218 -- Analyze the subtype definition and create temporaries for the bounds.
2219 -- Do not evaluate the range when preanalyzing a quantified expression
2220 -- because bounds expressed as function calls with side effects will be
2221 -- erroneously replicated.
2223 if Nkind (DS) = N_Range
2224 and then Expander_Active
2225 and then Nkind (Parent (N)) /= N_Quantified_Expression
2227 Process_Bounds (DS);
2229 -- Either the expander not active or the range of iteration is a subtype
2230 -- indication, an entity, or a function call that yields an aggregate or
2234 DS_Copy := New_Copy_Tree (DS);
2235 Set_Parent (DS_Copy, Parent (DS));
2236 Preanalyze_Range (DS_Copy);
2238 -- Ada 2012: If the domain of iteration is a function call, it is the
2239 -- new iterator form.
2241 if Nkind (DS_Copy) = N_Function_Call
2243 (Is_Entity_Name (DS_Copy)
2244 and then not Is_Type (Entity (DS_Copy)))
2246 -- This is an iterator specification. Rewrite it as such and
2247 -- analyze it to capture function calls that may require
2248 -- finalization actions.
2251 I_Spec : constant Node_Id :=
2252 Make_Iterator_Specification (Sloc (N),
2253 Defining_Identifier => Relocate_Node (Id),
2255 Subtype_Indication => Empty,
2256 Reverse_Present => Reverse_Present (N));
2257 Scheme : constant Node_Id := Parent (N);
2260 Set_Iterator_Specification (Scheme, I_Spec);
2261 Set_Loop_Parameter_Specification (Scheme, Empty);
2262 Analyze_Iterator_Specification (I_Spec);
2264 -- In a generic context, analyze the original domain of
2265 -- iteration, for name capture.
2267 if not Expander_Active then
2271 -- Set kind of loop parameter, which may be used in the
2272 -- subsequent analysis of the condition in a quantified
2275 Set_Ekind (Id, E_Loop_Parameter);
2279 -- Domain of iteration is not a function call, and is side-effect
2283 -- A quantified expression that appears in a pre/post condition
2284 -- is pre-analyzed several times. If the range is given by an
2285 -- attribute reference it is rewritten as a range, and this is
2286 -- done even with expansion disabled. If the type is already set
2287 -- do not reanalyze, because a range with static bounds may be
2288 -- typed Integer by default.
2290 if Nkind (Parent (N)) = N_Quantified_Expression
2291 and then Present (Etype (DS))
2304 -- Some additional checks if we are iterating through a type
2306 if Is_Entity_Name (DS)
2307 and then Present (Entity (DS))
2308 and then Is_Type (Entity (DS))
2310 -- The subtype indication may denote the completion of an incomplete
2311 -- type declaration.
2313 if Ekind (Entity (DS)) = E_Incomplete_Type then
2314 Set_Entity (DS, Get_Full_View (Entity (DS)));
2315 Set_Etype (DS, Entity (DS));
2318 -- Attempt to iterate through non-static predicate
2320 if Is_Discrete_Type (Entity (DS))
2321 and then Present (Predicate_Function (Entity (DS)))
2322 and then No (Static_Predicate (Entity (DS)))
2324 Bad_Predicated_Subtype_Use
2325 ("cannot use subtype& with non-static predicate for loop " &
2326 "iteration", DS, Entity (DS));
2330 -- Error if not discrete type
2332 if not Is_Discrete_Type (Etype (DS)) then
2333 Wrong_Type (DS, Any_Discrete);
2334 Set_Etype (DS, Any_Type);
2337 Check_Controlled_Array_Attribute (DS);
2339 Make_Index (DS, N, In_Iter_Schm => True);
2340 Set_Ekind (Id, E_Loop_Parameter);
2342 -- A quantified expression which appears in a pre- or post-condition may
2343 -- be analyzed multiple times. The analysis of the range creates several
2344 -- itypes which reside in different scopes depending on whether the pre-
2345 -- or post-condition has been expanded. Update the type of the loop
2346 -- variable to reflect the proper itype at each stage of analysis.
2349 or else Etype (Id) = Any_Type
2351 (Present (Etype (Id))
2352 and then Is_Itype (Etype (Id))
2353 and then Nkind (Parent (Loop_Nod)) = N_Expression_With_Actions
2354 and then Nkind (Original_Node (Parent (Loop_Nod))) =
2355 N_Quantified_Expression)
2357 Set_Etype (Id, Etype (DS));
2360 -- Treat a range as an implicit reference to the type, to inhibit
2361 -- spurious warnings.
2363 Generate_Reference (Base_Type (Etype (DS)), N, ' ');
2364 Set_Is_Known_Valid (Id, True);
2366 -- The loop is not a declarative part, so the loop variable must be
2367 -- frozen explicitly. Do not freeze while preanalyzing a quantified
2368 -- expression because the freeze node will not be inserted into the
2369 -- tree due to flag Is_Spec_Expression being set.
2371 if Nkind (Parent (N)) /= N_Quantified_Expression then
2373 Flist : constant List_Id := Freeze_Entity (Id, N);
2375 if Is_Non_Empty_List (Flist) then
2376 Insert_Actions (N, Flist);
2381 -- Check for null or possibly null range and issue warning. We suppress
2382 -- such messages in generic templates and instances, because in practice
2383 -- they tend to be dubious in these cases.
2385 if Nkind (DS) = N_Range and then Comes_From_Source (N) then
2387 L : constant Node_Id := Low_Bound (DS);
2388 H : constant Node_Id := High_Bound (DS);
2391 -- If range of loop is null, issue warning
2393 if Compile_Time_Compare (L, H, Assume_Valid => True) = GT then
2395 -- Suppress the warning if inside a generic template or
2396 -- instance, since in practice they tend to be dubious in these
2397 -- cases since they can result from intended parametrization.
2399 if not Inside_A_Generic
2400 and then not In_Instance
2402 -- Specialize msg if invalid values could make the loop
2403 -- non-null after all.
2405 if Compile_Time_Compare
2406 (L, H, Assume_Valid => False) = GT
2409 ("??loop range is null, loop will not execute", DS);
2411 -- Since we know the range of the loop is null, set the
2412 -- appropriate flag to remove the loop entirely during
2415 Set_Is_Null_Loop (Loop_Nod);
2417 -- Here is where the loop could execute because of invalid
2418 -- values, so issue appropriate message and in this case we
2419 -- do not set the Is_Null_Loop flag since the loop may
2424 ("??loop range may be null, loop may not execute",
2427 ("??can only execute if invalid values are present",
2432 -- In either case, suppress warnings in the body of the loop,
2433 -- since it is likely that these warnings will be inappropriate
2434 -- if the loop never actually executes, which is likely.
2436 Set_Suppress_Loop_Warnings (Loop_Nod);
2438 -- The other case for a warning is a reverse loop where the
2439 -- upper bound is the integer literal zero or one, and the
2440 -- lower bound can be positive.
2442 -- For example, we have
2444 -- for J in reverse N .. 1 loop
2446 -- In practice, this is very likely to be a case of reversing
2447 -- the bounds incorrectly in the range.
2449 elsif Reverse_Present (N)
2450 and then Nkind (Original_Node (H)) = N_Integer_Literal
2452 (Intval (Original_Node (H)) = Uint_0
2453 or else Intval (Original_Node (H)) = Uint_1)
2455 Error_Msg_N ("??loop range may be null", DS);
2456 Error_Msg_N ("\??bounds may be wrong way round", DS);
2460 end Analyze_Loop_Parameter_Specification;
2462 ----------------------------
2463 -- Analyze_Loop_Statement --
2464 ----------------------------
2466 procedure Analyze_Loop_Statement (N : Node_Id) is
2468 function Is_Container_Iterator (Iter : Node_Id) return Boolean;
2469 -- Given a loop iteration scheme, determine whether it is an Ada 2012
2470 -- container iteration.
2472 function Is_Wrapped_In_Block (N : Node_Id) return Boolean;
2473 -- Determine whether node N is the sole statement of a block
2475 ---------------------------
2476 -- Is_Container_Iterator --
2477 ---------------------------
2479 function Is_Container_Iterator (Iter : Node_Id) return Boolean is
2488 elsif Present (Condition (Iter)) then
2491 -- for Def_Id in [reverse] Name loop
2492 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
2494 elsif Present (Iterator_Specification (Iter)) then
2496 Nam : constant Node_Id := Name (Iterator_Specification (Iter));
2500 Nam_Copy := New_Copy_Tree (Nam);
2501 Set_Parent (Nam_Copy, Parent (Nam));
2502 Preanalyze_Range (Nam_Copy);
2504 -- The only two options here are iteration over a container or
2507 return not Is_Array_Type (Etype (Nam_Copy));
2510 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
2514 LP : constant Node_Id := Loop_Parameter_Specification (Iter);
2515 DS : constant Node_Id := Discrete_Subtype_Definition (LP);
2519 DS_Copy := New_Copy_Tree (DS);
2520 Set_Parent (DS_Copy, Parent (DS));
2521 Preanalyze_Range (DS_Copy);
2523 -- Check for a call to Iterate ()
2526 Nkind (DS_Copy) = N_Function_Call
2527 and then Needs_Finalization (Etype (DS_Copy));
2530 end Is_Container_Iterator;
2532 -------------------------
2533 -- Is_Wrapped_In_Block --
2534 -------------------------
2536 function Is_Wrapped_In_Block (N : Node_Id) return Boolean is
2537 HSS : constant Node_Id := Parent (N);
2541 Nkind (HSS) = N_Handled_Sequence_Of_Statements
2542 and then Nkind (Parent (HSS)) = N_Block_Statement
2543 and then First (Statements (HSS)) = N
2544 and then No (Next (First (Statements (HSS))));
2545 end Is_Wrapped_In_Block;
2547 -- Local declarations
2549 Id : constant Node_Id := Identifier (N);
2550 Iter : constant Node_Id := Iteration_Scheme (N);
2551 Loc : constant Source_Ptr := Sloc (N);
2554 -- Start of processing for Analyze_Loop_Statement
2557 if Present (Id) then
2559 -- Make name visible, e.g. for use in exit statements. Loop labels
2560 -- are always considered to be referenced.
2565 -- Guard against serious error (typically, a scope mismatch when
2566 -- semantic analysis is requested) by creating loop entity to
2567 -- continue analysis.
2570 if Total_Errors_Detected /= 0 then
2571 Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
2573 raise Program_Error;
2577 Generate_Reference (Ent, N, ' ');
2578 Generate_Definition (Ent);
2580 -- If we found a label, mark its type. If not, ignore it, since it
2581 -- means we have a conflicting declaration, which would already
2582 -- have been diagnosed at declaration time. Set Label_Construct
2583 -- of the implicit label declaration, which is not created by the
2584 -- parser for generic units.
2586 if Ekind (Ent) = E_Label then
2587 Set_Ekind (Ent, E_Loop);
2589 if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
2590 Set_Label_Construct (Parent (Ent), N);
2595 -- Case of no identifier present
2598 Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
2599 Set_Etype (Ent, Standard_Void_Type);
2600 Set_Parent (Ent, N);
2603 -- Iteration over a container in Ada 2012 involves the creation of a
2604 -- controlled iterator object. Wrap the loop in a block to ensure the
2605 -- timely finalization of the iterator and release of container locks.
2607 if Ada_Version >= Ada_2012
2608 and then Is_Container_Iterator (Iter)
2609 and then not Is_Wrapped_In_Block (N)
2612 Make_Block_Statement (Loc,
2613 Declarations => New_List,
2614 Handled_Statement_Sequence =>
2615 Make_Handled_Sequence_Of_Statements (Loc,
2616 Statements => New_List (Relocate_Node (N)))));
2622 -- Kill current values on entry to loop, since statements in the body of
2623 -- the loop may have been executed before the loop is entered. Similarly
2624 -- we kill values after the loop, since we do not know that the body of
2625 -- the loop was executed.
2627 Kill_Current_Values;
2629 Analyze_Iteration_Scheme (Iter);
2631 -- Check for following case which merits a warning if the type E of is
2632 -- a multi-dimensional array (and no explicit subscript ranges present).
2638 and then Present (Loop_Parameter_Specification (Iter))
2641 LPS : constant Node_Id := Loop_Parameter_Specification (Iter);
2642 DSD : constant Node_Id :=
2643 Original_Node (Discrete_Subtype_Definition (LPS));
2645 if Nkind (DSD) = N_Attribute_Reference
2646 and then Attribute_Name (DSD) = Name_Range
2647 and then No (Expressions (DSD))
2650 Typ : constant Entity_Id := Etype (Prefix (DSD));
2652 if Is_Array_Type (Typ)
2653 and then Number_Dimensions (Typ) > 1
2654 and then Nkind (Parent (N)) = N_Loop_Statement
2655 and then Present (Iteration_Scheme (Parent (N)))
2658 OIter : constant Node_Id :=
2659 Iteration_Scheme (Parent (N));
2660 OLPS : constant Node_Id :=
2661 Loop_Parameter_Specification (OIter);
2662 ODSD : constant Node_Id :=
2663 Original_Node (Discrete_Subtype_Definition (OLPS));
2665 if Nkind (ODSD) = N_Attribute_Reference
2666 and then Attribute_Name (ODSD) = Name_Range
2667 and then No (Expressions (ODSD))
2668 and then Etype (Prefix (ODSD)) = Typ
2670 Error_Msg_Sloc := Sloc (ODSD);
2672 ("inner range same as outer range#??", DSD);
2681 -- Analyze the statements of the body except in the case of an Ada 2012
2682 -- iterator with the expander active. In this case the expander will do
2683 -- a rewrite of the loop into a while loop. We will then analyze the
2684 -- loop body when we analyze this while loop.
2686 -- We need to do this delay because if the container is for indefinite
2687 -- types the actual subtype of the components will only be determined
2688 -- when the cursor declaration is analyzed.
2690 -- If the expander is not active, or in Alfa mode, then we want to
2691 -- analyze the loop body now even in the Ada 2012 iterator case, since
2692 -- the rewriting will not be done. Insert the loop variable in the
2693 -- current scope, if not done when analysing the iteration scheme.
2696 or else No (Iterator_Specification (Iter))
2697 or else not Full_Expander_Active
2700 and then Present (Iterator_Specification (Iter))
2703 Id : constant Entity_Id :=
2704 Defining_Identifier (Iterator_Specification (Iter));
2706 if Scope (Id) /= Current_Scope then
2712 Analyze_Statements (Statements (N));
2715 -- Finish up processing for the loop. We kill all current values, since
2716 -- in general we don't know if the statements in the loop have been
2717 -- executed. We could do a bit better than this with a loop that we
2718 -- know will execute at least once, but it's not worth the trouble and
2719 -- the front end is not in the business of flow tracing.
2721 Process_End_Label (N, 'e', Ent);
2723 Kill_Current_Values;
2725 -- Check for infinite loop. Skip check for generated code, since it
2726 -- justs waste time and makes debugging the routine called harder.
2728 -- Note that we have to wait till the body of the loop is fully analyzed
2729 -- before making this call, since Check_Infinite_Loop_Warning relies on
2730 -- being able to use semantic visibility information to find references.
2732 if Comes_From_Source (N) then
2733 Check_Infinite_Loop_Warning (N);
2736 -- Code after loop is unreachable if the loop has no WHILE or FOR and
2737 -- contains no EXIT statements within the body of the loop.
2739 if No (Iter) and then not Has_Exit (Ent) then
2740 Check_Unreachable_Code (N);
2742 end Analyze_Loop_Statement;
2744 ----------------------------
2745 -- Analyze_Null_Statement --
2746 ----------------------------
2748 -- Note: the semantics of the null statement is implemented by a single
2749 -- null statement, too bad everything isn't as simple as this!
2751 procedure Analyze_Null_Statement (N : Node_Id) is
2752 pragma Warnings (Off, N);
2755 end Analyze_Null_Statement;
2757 ------------------------
2758 -- Analyze_Statements --
2759 ------------------------
2761 procedure Analyze_Statements (L : List_Id) is
2766 -- The labels declared in the statement list are reachable from
2767 -- statements in the list. We do this as a prepass so that any goto
2768 -- statement will be properly flagged if its target is not reachable.
2769 -- This is not required, but is nice behavior!
2772 while Present (S) loop
2773 if Nkind (S) = N_Label then
2774 Analyze (Identifier (S));
2775 Lab := Entity (Identifier (S));
2777 -- If we found a label mark it as reachable
2779 if Ekind (Lab) = E_Label then
2780 Generate_Definition (Lab);
2781 Set_Reachable (Lab);
2783 if Nkind (Parent (Lab)) = N_Implicit_Label_Declaration then
2784 Set_Label_Construct (Parent (Lab), S);
2787 -- If we failed to find a label, it means the implicit declaration
2788 -- of the label was hidden. A for-loop parameter can do this to
2789 -- a label with the same name inside the loop, since the implicit
2790 -- label declaration is in the innermost enclosing body or block
2794 Error_Msg_Sloc := Sloc (Lab);
2796 ("implicit label declaration for & is hidden#",
2804 -- Perform semantic analysis on all statements
2806 Conditional_Statements_Begin;
2809 while Present (S) loop
2812 -- Remove dimension in all statements
2814 Remove_Dimension_In_Statement (S);
2818 Conditional_Statements_End;
2820 -- Make labels unreachable. Visibility is not sufficient, because labels
2821 -- in one if-branch for example are not reachable from the other branch,
2822 -- even though their declarations are in the enclosing declarative part.
2825 while Present (S) loop
2826 if Nkind (S) = N_Label then
2827 Set_Reachable (Entity (Identifier (S)), False);
2832 end Analyze_Statements;
2834 ----------------------------
2835 -- Check_Unreachable_Code --
2836 ----------------------------
2838 procedure Check_Unreachable_Code (N : Node_Id) is
2839 Error_Node : Node_Id;
2843 if Is_List_Member (N)
2844 and then Comes_From_Source (N)
2850 Nxt := Original_Node (Next (N));
2852 -- Skip past pragmas
2854 while Nkind (Nxt) = N_Pragma loop
2855 Nxt := Original_Node (Next (Nxt));
2858 -- If a label follows us, then we never have dead code, since
2859 -- someone could branch to the label, so we just ignore it, unless
2860 -- we are in formal mode where goto statements are not allowed.
2862 if Nkind (Nxt) = N_Label
2863 and then not Restriction_Check_Required (SPARK)
2867 -- Otherwise see if we have a real statement following us
2870 and then Comes_From_Source (Nxt)
2871 and then Is_Statement (Nxt)
2873 -- Special very annoying exception. If we have a return that
2874 -- follows a raise, then we allow it without a warning, since
2875 -- the Ada RM annoyingly requires a useless return here!
2877 if Nkind (Original_Node (N)) /= N_Raise_Statement
2878 or else Nkind (Nxt) /= N_Simple_Return_Statement
2880 -- The rather strange shenanigans with the warning message
2881 -- here reflects the fact that Kill_Dead_Code is very good
2882 -- at removing warnings in deleted code, and this is one
2883 -- warning we would prefer NOT to have removed.
2887 -- If we have unreachable code, analyze and remove the
2888 -- unreachable code, since it is useless and we don't
2889 -- want to generate junk warnings.
2891 -- We skip this step if we are not in code generation mode.
2892 -- This is the one case where we remove dead code in the
2893 -- semantics as opposed to the expander, and we do not want
2894 -- to remove code if we are not in code generation mode,
2895 -- since this messes up the ASIS trees.
2897 -- Note that one might react by moving the whole circuit to
2898 -- exp_ch5, but then we lose the warning in -gnatc mode.
2900 if Operating_Mode = Generate_Code then
2904 -- Quit deleting when we have nothing more to delete
2905 -- or if we hit a label (since someone could transfer
2906 -- control to a label, so we should not delete it).
2908 exit when No (Nxt) or else Nkind (Nxt) = N_Label;
2910 -- Statement/declaration is to be deleted
2914 Kill_Dead_Code (Nxt);
2918 -- Now issue the warning (or error in formal mode)
2920 if Restriction_Check_Required (SPARK) then
2921 Check_SPARK_Restriction
2922 ("unreachable code is not allowed", Error_Node);
2924 Error_Msg ("??unreachable code!", Sloc (Error_Node));
2928 -- If the unconditional transfer of control instruction is the
2929 -- last statement of a sequence, then see if our parent is one of
2930 -- the constructs for which we count unblocked exits, and if so,
2931 -- adjust the count.
2936 -- Statements in THEN part or ELSE part of IF statement
2938 if Nkind (P) = N_If_Statement then
2941 -- Statements in ELSIF part of an IF statement
2943 elsif Nkind (P) = N_Elsif_Part then
2945 pragma Assert (Nkind (P) = N_If_Statement);
2947 -- Statements in CASE statement alternative
2949 elsif Nkind (P) = N_Case_Statement_Alternative then
2951 pragma Assert (Nkind (P) = N_Case_Statement);
2953 -- Statements in body of block
2955 elsif Nkind (P) = N_Handled_Sequence_Of_Statements
2956 and then Nkind (Parent (P)) = N_Block_Statement
2960 -- Statements in exception handler in a block
2962 elsif Nkind (P) = N_Exception_Handler
2963 and then Nkind (Parent (P)) = N_Handled_Sequence_Of_Statements
2964 and then Nkind (Parent (Parent (P))) = N_Block_Statement
2968 -- None of these cases, so return
2974 -- This was one of the cases we are looking for (i.e. the
2975 -- parent construct was IF, CASE or block) so decrement count.
2977 Unblocked_Exit_Count := Unblocked_Exit_Count - 1;
2981 end Check_Unreachable_Code;
2983 ----------------------
2984 -- Preanalyze_Range --
2985 ----------------------
2987 procedure Preanalyze_Range (R_Copy : Node_Id) is
2988 Save_Analysis : constant Boolean := Full_Analysis;
2992 Full_Analysis := False;
2993 Expander_Mode_Save_And_Set (False);
2997 if Nkind (R_Copy) in N_Subexpr
2998 and then Is_Overloaded (R_Copy)
3000 -- Apply preference rules for range of predefined integer types, or
3001 -- diagnose true ambiguity.
3006 Found : Entity_Id := Empty;
3009 Get_First_Interp (R_Copy, I, It);
3010 while Present (It.Typ) loop
3011 if Is_Discrete_Type (It.Typ) then
3015 if Scope (Found) = Standard_Standard then
3018 elsif Scope (It.Typ) = Standard_Standard then
3022 -- Both of them are user-defined
3025 ("ambiguous bounds in range of iteration", R_Copy);
3026 Error_Msg_N ("\possible interpretations:", R_Copy);
3027 Error_Msg_NE ("\\} ", R_Copy, Found);
3028 Error_Msg_NE ("\\} ", R_Copy, It.Typ);
3034 Get_Next_Interp (I, It);
3039 -- Subtype mark in iteration scheme
3041 if Is_Entity_Name (R_Copy)
3042 and then Is_Type (Entity (R_Copy))
3046 -- Expression in range, or Ada 2012 iterator
3048 elsif Nkind (R_Copy) in N_Subexpr then
3050 Typ := Etype (R_Copy);
3052 if Is_Discrete_Type (Typ) then
3055 -- Check that the resulting object is an iterable container
3057 elsif Present (Find_Aspect (Typ, Aspect_Iterator_Element))
3058 or else Present (Find_Aspect (Typ, Aspect_Constant_Indexing))
3059 or else Present (Find_Aspect (Typ, Aspect_Variable_Indexing))
3063 -- The expression may yield an implicit reference to an iterable
3064 -- container. Insert explicit dereference so that proper type is
3065 -- visible in the loop.
3067 elsif Has_Implicit_Dereference (Etype (R_Copy)) then
3072 Disc := First_Discriminant (Typ);
3073 while Present (Disc) loop
3074 if Has_Implicit_Dereference (Disc) then
3075 Build_Explicit_Dereference (R_Copy, Disc);
3079 Next_Discriminant (Disc);
3086 Expander_Mode_Restore;
3087 Full_Analysis := Save_Analysis;
3088 end Preanalyze_Range;