1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2011, 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 Pre_Analyze_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
640 Msg => "(Ada 2005) null not allowed in null-excluding objects?",
641 Reason => CE_Null_Not_Allowed);
643 -- We still mark this as a possible modification, that's necessary
644 -- to reset Is_True_Constant, and desirable for xref purposes.
646 Note_Possible_Modification (Lhs, Sure => True);
649 -- If we know the right hand side is non-null, then we convert to the
650 -- target type, since we don't need a run time check in that case.
652 elsif not Can_Never_Be_Null (T2) then
653 Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
654 Analyze_And_Resolve (Rhs, T1);
658 if Is_Scalar_Type (T1) then
659 Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
661 -- For array types, verify that lengths match. If the right hand side
662 -- is a function call that has been inlined, the assignment has been
663 -- rewritten as a block, and the constraint check will be applied to the
664 -- assignment within the block.
666 elsif Is_Array_Type (T1)
668 (Nkind (Rhs) /= N_Type_Conversion
669 or else Is_Constrained (Etype (Rhs)))
671 (Nkind (Rhs) /= N_Function_Call
672 or else Nkind (N) /= N_Block_Statement)
674 -- Assignment verifies that the length of the Lsh and Rhs are equal,
675 -- but of course the indexes do not have to match. If the right-hand
676 -- side is a type conversion to an unconstrained type, a length check
677 -- is performed on the expression itself during expansion. In rare
678 -- cases, the redundant length check is computed on an index type
679 -- with a different representation, triggering incorrect code in the
682 Apply_Length_Check (Rhs, Etype (Lhs));
685 -- Discriminant checks are applied in the course of expansion
690 -- Note: modifications of the Lhs may only be recorded after
691 -- checks have been applied.
693 Note_Possible_Modification (Lhs, Sure => True);
694 Check_Order_Dependence;
696 -- ??? a real accessibility check is needed when ???
698 -- Post warning for redundant assignment or variable to itself
700 if Warn_On_Redundant_Constructs
702 -- We only warn for source constructs
704 and then Comes_From_Source (N)
706 -- Where the object is the same on both sides
708 and then Same_Object (Lhs, Original_Node (Rhs))
710 -- But exclude the case where the right side was an operation that
711 -- got rewritten (e.g. JUNK + K, where K was known to be zero). We
712 -- don't want to warn in such a case, since it is reasonable to write
713 -- such expressions especially when K is defined symbolically in some
716 and then Nkind (Original_Node (Rhs)) not in N_Op
718 if Nkind (Lhs) in N_Has_Entity then
719 Error_Msg_NE -- CODEFIX
720 ("?useless assignment of & to itself!", N, Entity (Lhs));
722 Error_Msg_N -- CODEFIX
723 ("?useless assignment of object to itself!", N);
727 -- Check for non-allowed composite assignment
729 if not Support_Composite_Assign_On_Target
730 and then (Is_Array_Type (T1) or else Is_Record_Type (T1))
731 and then (not Has_Size_Clause (T1) or else Esize (T1) > 64)
733 Error_Msg_CRT ("composite assignment", N);
736 -- Check elaboration warning for left side if not in elab code
738 if not In_Subprogram_Or_Concurrent_Unit then
739 Check_Elab_Assign (Lhs);
742 -- Set Referenced_As_LHS if appropriate. We only set this flag if the
743 -- assignment is a source assignment in the extended main source unit.
744 -- We are not interested in any reference information outside this
745 -- context, or in compiler generated assignment statements.
747 if Comes_From_Source (N)
748 and then In_Extended_Main_Source_Unit (Lhs)
750 Set_Referenced_Modified (Lhs, Out_Param => False);
753 -- Final step. If left side is an entity, then we may be able to reset
754 -- the current tracked values to new safe values. We only have something
755 -- to do if the left side is an entity name, and expansion has not
756 -- modified the node into something other than an assignment, and of
757 -- course we only capture values if it is safe to do so.
759 if Is_Entity_Name (Lhs)
760 and then Nkind (N) = N_Assignment_Statement
763 Ent : constant Entity_Id := Entity (Lhs);
766 if Safe_To_Capture_Value (N, Ent) then
768 -- If simple variable on left side, warn if this assignment
769 -- blots out another one (rendering it useless). We only do
770 -- this for source assignments, otherwise we can generate bogus
771 -- warnings when an assignment is rewritten as another
772 -- assignment, and gets tied up with itself.
774 if Warn_On_Modified_Unread
775 and then Is_Assignable (Ent)
776 and then Comes_From_Source (N)
777 and then In_Extended_Main_Source_Unit (Ent)
779 Warn_On_Useless_Assignment (Ent, N);
782 -- If we are assigning an access type and the left side is an
783 -- entity, then make sure that the Is_Known_[Non_]Null flags
784 -- properly reflect the state of the entity after assignment.
786 if Is_Access_Type (T1) then
787 if Known_Non_Null (Rhs) then
788 Set_Is_Known_Non_Null (Ent, True);
790 elsif Known_Null (Rhs)
791 and then not Can_Never_Be_Null (Ent)
793 Set_Is_Known_Null (Ent, True);
796 Set_Is_Known_Null (Ent, False);
798 if not Can_Never_Be_Null (Ent) then
799 Set_Is_Known_Non_Null (Ent, False);
803 -- For discrete types, we may be able to set the current value
804 -- if the value is known at compile time.
806 elsif Is_Discrete_Type (T1)
807 and then Compile_Time_Known_Value (Rhs)
809 Set_Current_Value (Ent, Rhs);
811 Set_Current_Value (Ent, Empty);
814 -- If not safe to capture values, kill them
822 -- If assigning to an object in whole or in part, note location of
823 -- assignment in case no one references value. We only do this for
824 -- source assignments, otherwise we can generate bogus warnings when an
825 -- assignment is rewritten as another assignment, and gets tied up with
829 Ent : constant Entity_Id := Get_Enclosing_Object (Lhs);
832 and then Safe_To_Capture_Value (N, Ent)
833 and then Nkind (N) = N_Assignment_Statement
834 and then Warn_On_Modified_Unread
835 and then Is_Assignable (Ent)
836 and then Comes_From_Source (N)
837 and then In_Extended_Main_Source_Unit (Ent)
839 Set_Last_Assignment (Ent, Lhs);
843 Analyze_Dimension (N);
844 end Analyze_Assignment;
846 -----------------------------
847 -- Analyze_Block_Statement --
848 -----------------------------
850 procedure Analyze_Block_Statement (N : Node_Id) is
851 procedure Install_Return_Entities (Scop : Entity_Id);
852 -- Install all entities of return statement scope Scop in the visibility
853 -- chain except for the return object since its entity is reused in a
856 -----------------------------
857 -- Install_Return_Entities --
858 -----------------------------
860 procedure Install_Return_Entities (Scop : Entity_Id) is
864 Id := First_Entity (Scop);
865 while Present (Id) loop
867 -- Do not install the return object
869 if not Ekind_In (Id, E_Constant, E_Variable)
870 or else not Is_Return_Object (Id)
877 end Install_Return_Entities;
879 -- Local constants and variables
881 Decls : constant List_Id := Declarations (N);
882 Id : constant Node_Id := Identifier (N);
883 HSS : constant Node_Id := Handled_Statement_Sequence (N);
885 Is_BIP_Return_Statement : Boolean;
887 -- Start of processing for Analyze_Block_Statement
890 -- In SPARK mode, we reject block statements. Note that the case of
891 -- block statements generated by the expander is fine.
893 if Nkind (Original_Node (N)) = N_Block_Statement then
894 Check_SPARK_Restriction ("block statement is not allowed", N);
897 -- If no handled statement sequence is present, things are really messed
898 -- up, and we just return immediately (defence against previous errors).
904 -- Detect whether the block is actually a rewritten return statement of
905 -- a build-in-place function.
907 Is_BIP_Return_Statement :=
909 and then Present (Entity (Id))
910 and then Ekind (Entity (Id)) = E_Return_Statement
911 and then Is_Build_In_Place_Function
912 (Return_Applies_To (Entity (Id)));
914 -- Normal processing with HSS present
917 EH : constant List_Id := Exception_Handlers (HSS);
918 Ent : Entity_Id := Empty;
921 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
922 -- Recursively save value of this global, will be restored on exit
925 -- Initialize unblocked exit count for statements of begin block
926 -- plus one for each exception handler that is present.
928 Unblocked_Exit_Count := 1;
931 Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH);
934 -- If a label is present analyze it and mark it as referenced
940 -- An error defense. If we have an identifier, but no entity, then
941 -- something is wrong. If previous errors, then just remove the
942 -- identifier and continue, otherwise raise an exception.
945 if Total_Errors_Detected /= 0 then
946 Set_Identifier (N, Empty);
952 Set_Ekind (Ent, E_Block);
953 Generate_Reference (Ent, N, ' ');
954 Generate_Definition (Ent);
956 if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
957 Set_Label_Construct (Parent (Ent), N);
962 -- If no entity set, create a label entity
965 Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B');
966 Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N)));
970 Set_Etype (Ent, Standard_Void_Type);
971 Set_Block_Node (Ent, Identifier (N));
974 -- The block served as an extended return statement. Ensure that any
975 -- entities created during the analysis and expansion of the return
976 -- object declaration are once again visible.
978 if Is_BIP_Return_Statement then
979 Install_Return_Entities (Ent);
982 if Present (Decls) then
983 Analyze_Declarations (Decls);
985 Inspect_Deferred_Constant_Completion (Decls);
989 Process_End_Label (HSS, 'e', Ent);
991 -- If exception handlers are present, then we indicate that enclosing
992 -- scopes contain a block with handlers. We only need to mark non-
998 Set_Has_Nested_Block_With_Handler (S);
999 exit when Is_Overloadable (S)
1000 or else Ekind (S) = E_Package
1001 or else Is_Generic_Unit (S);
1006 Check_References (Ent);
1007 Warn_On_Useless_Assignments (Ent);
1010 if Unblocked_Exit_Count = 0 then
1011 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1012 Check_Unreachable_Code (N);
1014 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1017 end Analyze_Block_Statement;
1019 ----------------------------
1020 -- Analyze_Case_Statement --
1021 ----------------------------
1023 procedure Analyze_Case_Statement (N : Node_Id) is
1025 Exp_Type : Entity_Id;
1026 Exp_Btype : Entity_Id;
1028 Dont_Care : Boolean;
1029 Others_Present : Boolean;
1031 pragma Warnings (Off, Last_Choice);
1032 pragma Warnings (Off, Dont_Care);
1033 -- Don't care about assigned values
1035 Statements_Analyzed : Boolean := False;
1036 -- Set True if at least some statement sequences get analyzed. If False
1037 -- on exit, means we had a serious error that prevented full analysis of
1038 -- the case statement, and as a result it is not a good idea to output
1039 -- warning messages about unreachable code.
1041 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
1042 -- Recursively save value of this global, will be restored on exit
1044 procedure Non_Static_Choice_Error (Choice : Node_Id);
1045 -- Error routine invoked by the generic instantiation below when the
1046 -- case statement has a non static choice.
1048 procedure Process_Statements (Alternative : Node_Id);
1049 -- Analyzes all the statements associated with a case alternative.
1050 -- Needed by the generic instantiation below.
1052 package Case_Choices_Processing is new
1053 Generic_Choices_Processing
1054 (Get_Alternatives => Alternatives,
1055 Get_Choices => Discrete_Choices,
1056 Process_Empty_Choice => No_OP,
1057 Process_Non_Static_Choice => Non_Static_Choice_Error,
1058 Process_Associated_Node => Process_Statements);
1059 use Case_Choices_Processing;
1060 -- Instantiation of the generic choice processing package
1062 -----------------------------
1063 -- Non_Static_Choice_Error --
1064 -----------------------------
1066 procedure Non_Static_Choice_Error (Choice : Node_Id) is
1068 Flag_Non_Static_Expr
1069 ("choice given in case statement is not static!", Choice);
1070 end Non_Static_Choice_Error;
1072 ------------------------
1073 -- Process_Statements --
1074 ------------------------
1076 procedure Process_Statements (Alternative : Node_Id) is
1077 Choices : constant List_Id := Discrete_Choices (Alternative);
1081 Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
1082 Statements_Analyzed := True;
1084 -- An interesting optimization. If the case statement expression
1085 -- is a simple entity, then we can set the current value within an
1086 -- alternative if the alternative has one possible value.
1090 -- when 2 | 3 => beta
1091 -- when others => gamma
1093 -- Here we know that N is initially 1 within alpha, but for beta and
1094 -- gamma, we do not know anything more about the initial value.
1096 if Is_Entity_Name (Exp) then
1097 Ent := Entity (Exp);
1099 if Ekind_In (Ent, E_Variable,
1103 if List_Length (Choices) = 1
1104 and then Nkind (First (Choices)) in N_Subexpr
1105 and then Compile_Time_Known_Value (First (Choices))
1107 Set_Current_Value (Entity (Exp), First (Choices));
1110 Analyze_Statements (Statements (Alternative));
1112 -- After analyzing the case, set the current value to empty
1113 -- since we won't know what it is for the next alternative
1114 -- (unless reset by this same circuit), or after the case.
1116 Set_Current_Value (Entity (Exp), Empty);
1121 -- Case where expression is not an entity name of a variable
1123 Analyze_Statements (Statements (Alternative));
1124 end Process_Statements;
1126 -- Start of processing for Analyze_Case_Statement
1129 Unblocked_Exit_Count := 0;
1130 Exp := Expression (N);
1133 -- The expression must be of any discrete type. In rare cases, the
1134 -- expander constructs a case statement whose expression has a private
1135 -- type whose full view is discrete. This can happen when generating
1136 -- a stream operation for a variant type after the type is frozen,
1137 -- when the partial of view of the type of the discriminant is private.
1138 -- In that case, use the full view to analyze case alternatives.
1140 if not Is_Overloaded (Exp)
1141 and then not Comes_From_Source (N)
1142 and then Is_Private_Type (Etype (Exp))
1143 and then Present (Full_View (Etype (Exp)))
1144 and then Is_Discrete_Type (Full_View (Etype (Exp)))
1146 Resolve (Exp, Etype (Exp));
1147 Exp_Type := Full_View (Etype (Exp));
1150 Analyze_And_Resolve (Exp, Any_Discrete);
1151 Exp_Type := Etype (Exp);
1154 Check_Unset_Reference (Exp);
1155 Exp_Btype := Base_Type (Exp_Type);
1157 -- The expression must be of a discrete type which must be determinable
1158 -- independently of the context in which the expression occurs, but
1159 -- using the fact that the expression must be of a discrete type.
1160 -- Moreover, the type this expression must not be a character literal
1161 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
1163 -- If error already reported by Resolve, nothing more to do
1165 if Exp_Btype = Any_Discrete
1166 or else Exp_Btype = Any_Type
1170 elsif Exp_Btype = Any_Character then
1172 ("character literal as case expression is ambiguous", Exp);
1175 elsif Ada_Version = Ada_83
1176 and then (Is_Generic_Type (Exp_Btype)
1177 or else Is_Generic_Type (Root_Type (Exp_Btype)))
1180 ("(Ada 83) case expression cannot be of a generic type", Exp);
1184 -- If the case expression is a formal object of mode in out, then treat
1185 -- it as having a nonstatic subtype by forcing use of the base type
1186 -- (which has to get passed to Check_Case_Choices below). Also use base
1187 -- type when the case expression is parenthesized.
1189 if Paren_Count (Exp) > 0
1190 or else (Is_Entity_Name (Exp)
1191 and then Ekind (Entity (Exp)) = E_Generic_In_Out_Parameter)
1193 Exp_Type := Exp_Btype;
1196 -- Call instantiated Analyze_Choices which does the rest of the work
1198 Analyze_Choices (N, Exp_Type, Dont_Care, Others_Present);
1200 -- A case statement with a single OTHERS alternative is not allowed
1204 and then List_Length (Alternatives (N)) = 1
1206 Check_SPARK_Restriction
1207 ("OTHERS as unique case alternative is not allowed", N);
1210 if Exp_Type = Universal_Integer and then not Others_Present then
1211 Error_Msg_N ("case on universal integer requires OTHERS choice", Exp);
1214 -- If all our exits were blocked by unconditional transfers of control,
1215 -- then the entire CASE statement acts as an unconditional transfer of
1216 -- control, so treat it like one, and check unreachable code. Skip this
1217 -- test if we had serious errors preventing any statement analysis.
1219 if Unblocked_Exit_Count = 0 and then Statements_Analyzed then
1220 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1221 Check_Unreachable_Code (N);
1223 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1226 if not Expander_Active
1227 and then Compile_Time_Known_Value (Expression (N))
1228 and then Serious_Errors_Detected = 0
1231 Chosen : constant Node_Id := Find_Static_Alternative (N);
1235 Alt := First (Alternatives (N));
1236 while Present (Alt) loop
1237 if Alt /= Chosen then
1238 Remove_Warning_Messages (Statements (Alt));
1245 end Analyze_Case_Statement;
1247 ----------------------------
1248 -- Analyze_Exit_Statement --
1249 ----------------------------
1251 -- If the exit includes a name, it must be the name of a currently open
1252 -- loop. Otherwise there must be an innermost open loop on the stack, to
1253 -- which the statement implicitly refers.
1255 -- Additionally, in SPARK mode:
1257 -- The exit can only name the closest enclosing loop;
1259 -- An exit with a when clause must be directly contained in a loop;
1261 -- An exit without a when clause must be directly contained in an
1262 -- if-statement with no elsif or else, which is itself directly contained
1263 -- in a loop. The exit must be the last statement in the if-statement.
1265 procedure Analyze_Exit_Statement (N : Node_Id) is
1266 Target : constant Node_Id := Name (N);
1267 Cond : constant Node_Id := Condition (N);
1268 Scope_Id : Entity_Id;
1274 Check_Unreachable_Code (N);
1277 if Present (Target) then
1279 U_Name := Entity (Target);
1281 if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then
1282 Error_Msg_N ("invalid loop name in exit statement", N);
1286 if Has_Loop_In_Inner_Open_Scopes (U_Name) then
1287 Check_SPARK_Restriction
1288 ("exit label must name the closest enclosing loop", N);
1291 Set_Has_Exit (U_Name);
1298 for J in reverse 0 .. Scope_Stack.Last loop
1299 Scope_Id := Scope_Stack.Table (J).Entity;
1300 Kind := Ekind (Scope_Id);
1303 and then (No (Target) or else Scope_Id = U_Name)
1305 Set_Has_Exit (Scope_Id);
1308 elsif Kind = E_Block
1309 or else Kind = E_Loop
1310 or else Kind = E_Return_Statement
1316 ("cannot exit from program unit or accept statement", N);
1321 -- Verify that if present the condition is a Boolean expression
1323 if Present (Cond) then
1324 Analyze_And_Resolve (Cond, Any_Boolean);
1325 Check_Unset_Reference (Cond);
1328 -- In SPARK mode, verify that the exit statement respects the SPARK
1331 if Present (Cond) then
1332 if Nkind (Parent (N)) /= N_Loop_Statement then
1333 Check_SPARK_Restriction
1334 ("exit with when clause must be directly in loop", N);
1338 if Nkind (Parent (N)) /= N_If_Statement then
1339 if Nkind (Parent (N)) = N_Elsif_Part then
1340 Check_SPARK_Restriction
1341 ("exit must be in IF without ELSIF", N);
1343 Check_SPARK_Restriction ("exit must be directly in IF", N);
1346 elsif Nkind (Parent (Parent (N))) /= N_Loop_Statement then
1347 Check_SPARK_Restriction
1348 ("exit must be in IF directly in loop", N);
1350 -- First test the presence of ELSE, so that an exit in an ELSE leads
1351 -- to an error mentioning the ELSE.
1353 elsif Present (Else_Statements (Parent (N))) then
1354 Check_SPARK_Restriction ("exit must be in IF without ELSE", N);
1356 -- An exit in an ELSIF does not reach here, as it would have been
1357 -- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
1359 elsif Present (Elsif_Parts (Parent (N))) then
1360 Check_SPARK_Restriction ("exit must be in IF without ELSIF", N);
1364 -- Chain exit statement to associated loop entity
1366 Set_Next_Exit_Statement (N, First_Exit_Statement (Scope_Id));
1367 Set_First_Exit_Statement (Scope_Id, N);
1369 -- Since the exit may take us out of a loop, any previous assignment
1370 -- statement is not useless, so clear last assignment indications. It
1371 -- is OK to keep other current values, since if the exit statement
1372 -- does not exit, then the current values are still valid.
1374 Kill_Current_Values (Last_Assignment_Only => True);
1375 end Analyze_Exit_Statement;
1377 ----------------------------
1378 -- Analyze_Goto_Statement --
1379 ----------------------------
1381 procedure Analyze_Goto_Statement (N : Node_Id) is
1382 Label : constant Node_Id := Name (N);
1383 Scope_Id : Entity_Id;
1384 Label_Scope : Entity_Id;
1385 Label_Ent : Entity_Id;
1388 Check_SPARK_Restriction ("goto statement is not allowed", N);
1390 -- Actual semantic checks
1392 Check_Unreachable_Code (N);
1393 Kill_Current_Values (Last_Assignment_Only => True);
1396 Label_Ent := Entity (Label);
1398 -- Ignore previous error
1400 if Label_Ent = Any_Id then
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 procedure Process_Bounds (R : Node_Id);
1612 -- If the iteration is given by a range, create temporaries and
1613 -- assignment statements block to capture the bounds and perform
1614 -- required finalization actions in case a bound includes a function
1615 -- call that uses the temporary stack. We first pre-analyze a copy of
1616 -- the range in order to determine the expected type, and analyze and
1617 -- resolve the original bounds.
1619 procedure Check_Controlled_Array_Attribute (DS : Node_Id);
1620 -- If the bounds are given by a 'Range reference on a function call
1621 -- that returns a controlled array, introduce an explicit declaration
1622 -- to capture the bounds, so that the function result can be finalized
1623 -- in timely fashion.
1625 function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean;
1626 -- N is the node for an arbitrary construct. This function searches the
1627 -- construct N to see if any expressions within it contain function
1628 -- calls that use the secondary stack, returning True if any such call
1629 -- is found, and False otherwise.
1631 --------------------
1632 -- Process_Bounds --
1633 --------------------
1635 procedure Process_Bounds (R : Node_Id) is
1636 Loc : constant Source_Ptr := Sloc (N);
1637 R_Copy : constant Node_Id := New_Copy_Tree (R);
1638 Lo : constant Node_Id := Low_Bound (R);
1639 Hi : constant Node_Id := High_Bound (R);
1640 New_Lo_Bound : Node_Id;
1641 New_Hi_Bound : Node_Id;
1645 (Original_Bound : Node_Id;
1646 Analyzed_Bound : Node_Id) return Node_Id;
1647 -- Capture value of bound and return captured value
1654 (Original_Bound : Node_Id;
1655 Analyzed_Bound : Node_Id) return Node_Id
1662 -- If the bound is a constant or an object, no need for a separate
1663 -- declaration. If the bound is the result of previous expansion
1664 -- it is already analyzed and should not be modified. Note that
1665 -- the Bound will be resolved later, if needed, as part of the
1666 -- call to Make_Index (literal bounds may need to be resolved to
1669 if Analyzed (Original_Bound) then
1670 return Original_Bound;
1672 elsif Nkind_In (Analyzed_Bound, N_Integer_Literal,
1673 N_Character_Literal)
1674 or else Is_Entity_Name (Analyzed_Bound)
1676 Analyze_And_Resolve (Original_Bound, Typ);
1677 return Original_Bound;
1680 -- Here we need to capture the value
1682 Analyze_And_Resolve (Original_Bound, Typ);
1684 -- Normally, the best approach is simply to generate a constant
1685 -- declaration that captures the bound. However, there is a nasty
1686 -- case where this is wrong. If the bound is complex, and has a
1687 -- possible use of the secondary stack, we need to generate a
1688 -- separate assignment statement to ensure the creation of a block
1689 -- which will release the secondary stack.
1691 -- We prefer the constant declaration, since it leaves us with a
1692 -- proper trace of the value, useful in optimizations that get rid
1693 -- of junk range checks.
1695 if not Has_Call_Using_Secondary_Stack (Original_Bound) then
1696 Force_Evaluation (Original_Bound);
1697 return Original_Bound;
1700 Id := Make_Temporary (Loc, 'R', Original_Bound);
1702 -- Here we make a declaration with a separate assignment
1703 -- statement, and insert before loop header.
1706 Make_Object_Declaration (Loc,
1707 Defining_Identifier => Id,
1708 Object_Definition => New_Occurrence_Of (Typ, Loc));
1711 Make_Assignment_Statement (Loc,
1712 Name => New_Occurrence_Of (Id, Loc),
1713 Expression => Relocate_Node (Original_Bound));
1715 -- We must recursively clean in the relocated expression the flag
1716 -- analyzed to ensure that the expression is reanalyzed. Required
1717 -- to ensure that the transient scope is established now (because
1718 -- Establish_Transient_Scope discarded generating transient scopes
1719 -- in the analysis of the iteration scheme).
1721 Reset_Analyzed_Flags (Expression (Assign));
1723 Insert_Actions (Parent (N), New_List (Decl, Assign));
1725 -- Now that this temporary variable is initialized we decorate it
1726 -- as safe-to-reevaluate to inform to the backend that no further
1727 -- asignment will be issued and hence it can be handled as side
1728 -- effect free. Note that this decoration must be done when the
1729 -- assignment has been analyzed because otherwise it will be
1730 -- rejected (see Analyze_Assignment).
1732 Set_Is_Safe_To_Reevaluate (Id);
1734 Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc));
1736 if Nkind (Assign) = N_Assignment_Statement then
1737 return Expression (Assign);
1739 return Original_Bound;
1743 -- Start of processing for Process_Bounds
1746 Set_Parent (R_Copy, Parent (R));
1747 Pre_Analyze_Range (R_Copy);
1748 Typ := Etype (R_Copy);
1750 -- If the type of the discrete range is Universal_Integer, then the
1751 -- bound's type must be resolved to Integer, and any object used to
1752 -- hold the bound must also have type Integer, unless the literal
1753 -- bounds are constant-folded expressions with a user-defined type.
1755 if Typ = Universal_Integer then
1756 if Nkind (Lo) = N_Integer_Literal
1757 and then Present (Etype (Lo))
1758 and then Scope (Etype (Lo)) /= Standard_Standard
1762 elsif Nkind (Hi) = N_Integer_Literal
1763 and then Present (Etype (Hi))
1764 and then Scope (Etype (Hi)) /= Standard_Standard
1769 Typ := Standard_Integer;
1775 New_Lo_Bound := One_Bound (Lo, Low_Bound (R_Copy));
1776 New_Hi_Bound := One_Bound (Hi, High_Bound (R_Copy));
1778 -- Propagate staticness to loop range itself, in case the
1779 -- corresponding subtype is static.
1781 if New_Lo_Bound /= Lo
1782 and then Is_Static_Expression (New_Lo_Bound)
1784 Rewrite (Low_Bound (R), New_Copy (New_Lo_Bound));
1787 if New_Hi_Bound /= Hi
1788 and then Is_Static_Expression (New_Hi_Bound)
1790 Rewrite (High_Bound (R), New_Copy (New_Hi_Bound));
1794 --------------------------------------
1795 -- Check_Controlled_Array_Attribute --
1796 --------------------------------------
1798 procedure Check_Controlled_Array_Attribute (DS : Node_Id) is
1800 if Nkind (DS) = N_Attribute_Reference
1801 and then Is_Entity_Name (Prefix (DS))
1802 and then Ekind (Entity (Prefix (DS))) = E_Function
1803 and then Is_Array_Type (Etype (Entity (Prefix (DS))))
1806 Component_Type (Etype (Entity (Prefix (DS)))))
1807 and then Expander_Active
1810 Loc : constant Source_Ptr := Sloc (N);
1811 Arr : constant Entity_Id := Etype (Entity (Prefix (DS)));
1812 Indx : constant Entity_Id :=
1813 Base_Type (Etype (First_Index (Arr)));
1814 Subt : constant Entity_Id := Make_Temporary (Loc, 'S');
1819 Make_Subtype_Declaration (Loc,
1820 Defining_Identifier => Subt,
1821 Subtype_Indication =>
1822 Make_Subtype_Indication (Loc,
1823 Subtype_Mark => New_Reference_To (Indx, Loc),
1825 Make_Range_Constraint (Loc,
1826 Relocate_Node (DS))));
1827 Insert_Before (Parent (N), Decl);
1831 Make_Attribute_Reference (Loc,
1832 Prefix => New_Reference_To (Subt, Loc),
1833 Attribute_Name => Attribute_Name (DS)));
1837 end Check_Controlled_Array_Attribute;
1839 ------------------------------------
1840 -- Has_Call_Using_Secondary_Stack --
1841 ------------------------------------
1843 function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean is
1845 function Check_Call (N : Node_Id) return Traverse_Result;
1846 -- Check if N is a function call which uses the secondary stack
1852 function Check_Call (N : Node_Id) return Traverse_Result is
1855 Return_Typ : Entity_Id;
1858 if Nkind (N) = N_Function_Call then
1861 -- Call using access to subprogram with explicit dereference
1863 if Nkind (Nam) = N_Explicit_Dereference then
1864 Subp := Etype (Nam);
1869 Subp := Entity (Nam);
1872 Return_Typ := Etype (Subp);
1874 if Is_Composite_Type (Return_Typ)
1875 and then not Is_Constrained (Return_Typ)
1879 elsif Sec_Stack_Needed_For_Return (Subp) then
1884 -- Continue traversing the tree
1889 function Check_Calls is new Traverse_Func (Check_Call);
1891 -- Start of processing for Has_Call_Using_Secondary_Stack
1894 return Check_Calls (N) = Abandon;
1895 end Has_Call_Using_Secondary_Stack;
1897 -- Start of processing for Analyze_Iteration_Scheme
1900 -- If this is a rewritten quantified expression, the iteration scheme
1901 -- has been analyzed already. Do no repeat analysis because the loop
1902 -- variable is already declared.
1904 if Analyzed (N) then
1908 -- For an infinite loop, there is no iteration scheme
1914 -- Iteration scheme is present
1917 Cond : constant Node_Id := Condition (N);
1920 -- For WHILE loop, verify that the condition is a Boolean expression
1921 -- and resolve and check it.
1923 if Present (Cond) then
1924 Analyze_And_Resolve (Cond, Any_Boolean);
1925 Check_Unset_Reference (Cond);
1926 Set_Current_Value_Condition (N);
1929 -- For an iterator specification with "of", pre-analyze range to
1930 -- capture function calls that may require finalization actions.
1932 elsif Present (Iterator_Specification (N)) then
1933 Pre_Analyze_Range (Name (Iterator_Specification (N)));
1934 Analyze_Iterator_Specification (Iterator_Specification (N));
1936 -- Else we have a FOR loop
1940 LP : constant Node_Id := Loop_Parameter_Specification (N);
1941 Id : constant Entity_Id := Defining_Identifier (LP);
1942 DS : constant Node_Id := Discrete_Subtype_Definition (LP);
1949 -- We always consider the loop variable to be referenced, since
1950 -- the loop may be used just for counting purposes.
1952 Generate_Reference (Id, N, ' ');
1954 -- Check for the case of loop variable hiding a local variable
1955 -- (used later on to give a nice warning if the hidden variable
1956 -- is never assigned).
1959 H : constant Entity_Id := Homonym (Id);
1962 and then Enclosing_Dynamic_Scope (H) =
1963 Enclosing_Dynamic_Scope (Id)
1964 and then Ekind (H) = E_Variable
1965 and then Is_Discrete_Type (Etype (H))
1967 Set_Hiding_Loop_Variable (H, Id);
1971 -- Loop parameter specification must include subtype mark in
1974 if Nkind (DS) = N_Range then
1975 Check_SPARK_Restriction
1976 ("loop parameter specification must include subtype mark",
1980 -- Now analyze the subtype definition. If it is a range, create
1981 -- temporaries for bounds.
1983 if Nkind (DS) = N_Range
1984 and then Expander_Active
1986 Process_Bounds (DS);
1988 -- Expander not active or else range of iteration is a subtype
1989 -- indication, an entity, or a function call that yields an
1990 -- aggregate or a container.
1993 D_Copy := New_Copy_Tree (DS);
1994 Set_Parent (D_Copy, Parent (DS));
1995 Pre_Analyze_Range (D_Copy);
1997 -- Ada 2012: If the domain of iteration is a function call,
1998 -- it is the new iterator form.
2000 -- We have also implemented the shorter form : for X in S
2001 -- for Alfa use. In this case, 'Old and 'Result must be
2002 -- treated as entity names over which iterators are legal.
2004 if Nkind (D_Copy) = N_Function_Call
2007 and then (Nkind (D_Copy) = N_Attribute_Reference
2009 (Attribute_Name (D_Copy) = Name_Result
2010 or else Attribute_Name (D_Copy) = Name_Old)))
2012 (Is_Entity_Name (D_Copy)
2013 and then not Is_Type (Entity (D_Copy)))
2015 -- This is an iterator specification. Rewrite as such
2016 -- and analyze, to capture function calls that may
2017 -- require finalization actions.
2020 I_Spec : constant Node_Id :=
2021 Make_Iterator_Specification (Sloc (LP),
2022 Defining_Identifier =>
2025 Subtype_Indication => Empty,
2027 Reverse_Present (LP));
2029 Set_Iterator_Specification (N, I_Spec);
2030 Set_Loop_Parameter_Specification (N, Empty);
2031 Analyze_Iterator_Specification (I_Spec);
2033 -- In a generic context, analyze the original domain
2034 -- of iteration, for name capture.
2036 if not Expander_Active then
2040 -- Set kind of loop parameter, which may be used in
2041 -- the subsequent analysis of the condition in a
2042 -- quantified expression.
2044 Set_Ekind (Id, E_Loop_Parameter);
2048 -- Domain of iteration is not a function call, and is
2049 -- side-effect free.
2060 -- Some additional checks if we are iterating through a type
2062 if Is_Entity_Name (DS)
2063 and then Present (Entity (DS))
2064 and then Is_Type (Entity (DS))
2066 -- The subtype indication may denote the completion of an
2067 -- incomplete type declaration.
2069 if Ekind (Entity (DS)) = E_Incomplete_Type then
2070 Set_Entity (DS, Get_Full_View (Entity (DS)));
2071 Set_Etype (DS, Entity (DS));
2074 -- Attempt to iterate through non-static predicate
2076 if Is_Discrete_Type (Entity (DS))
2077 and then Present (Predicate_Function (Entity (DS)))
2078 and then No (Static_Predicate (Entity (DS)))
2080 Bad_Predicated_Subtype_Use
2081 ("cannot use subtype& with non-static "
2082 & "predicate for loop iteration", DS, Entity (DS));
2086 -- Error if not discrete type
2088 if not Is_Discrete_Type (Etype (DS)) then
2089 Wrong_Type (DS, Any_Discrete);
2090 Set_Etype (DS, Any_Type);
2093 Check_Controlled_Array_Attribute (DS);
2095 Make_Index (DS, LP, In_Iter_Schm => True);
2097 Set_Ekind (Id, E_Loop_Parameter);
2099 -- If the loop is part of a predicate or precondition, it may
2100 -- be analyzed twice, once in the source and once on the copy
2101 -- used to check conformance. Preserve the original itype
2102 -- because the second one may be created in a different scope,
2103 -- e.g. a precondition procedure, leading to a crash in GIGI.
2105 if No (Etype (Id)) or else Etype (Id) = Any_Type then
2106 Set_Etype (Id, Etype (DS));
2109 -- Treat a range as an implicit reference to the type, to
2110 -- inhibit spurious warnings.
2112 Generate_Reference (Base_Type (Etype (DS)), N, ' ');
2113 Set_Is_Known_Valid (Id, True);
2115 -- The loop is not a declarative part, so the only entity
2116 -- declared "within" must be frozen explicitly.
2119 Flist : constant List_Id := Freeze_Entity (Id, N);
2121 if Is_Non_Empty_List (Flist) then
2122 Insert_Actions (N, Flist);
2126 -- Check for null or possibly null range and issue warning. We
2127 -- suppress such messages in generic templates and instances,
2128 -- because in practice they tend to be dubious in these cases.
2130 if Nkind (DS) = N_Range and then Comes_From_Source (N) then
2132 L : constant Node_Id := Low_Bound (DS);
2133 H : constant Node_Id := High_Bound (DS);
2136 -- If range of loop is null, issue warning
2138 if Compile_Time_Compare
2139 (L, H, Assume_Valid => True) = GT
2141 -- Suppress the warning if inside a generic template
2142 -- or instance, since in practice they tend to be
2143 -- dubious in these cases since they can result from
2144 -- intended parametrization.
2146 if not Inside_A_Generic
2147 and then not In_Instance
2149 -- Specialize msg if invalid values could make the
2150 -- loop non-null after all.
2152 if Compile_Time_Compare
2153 (L, H, Assume_Valid => False) = GT
2156 ("?loop range is null, loop will not execute",
2159 -- Since we know the range of the loop is null,
2160 -- set the appropriate flag to remove the loop
2161 -- entirely during expansion.
2163 Set_Is_Null_Loop (Parent (N));
2165 -- Here is where the loop could execute because
2166 -- of invalid values, so issue appropriate
2167 -- message and in this case we do not set the
2168 -- Is_Null_Loop flag since the loop may execute.
2172 ("?loop range may be null, "
2173 & "loop may not execute",
2176 ("?can only execute if invalid values "
2182 -- In either case, suppress warnings in the body of
2183 -- the loop, since it is likely that these warnings
2184 -- will be inappropriate if the loop never actually
2185 -- executes, which is likely.
2187 Set_Suppress_Loop_Warnings (Parent (N));
2189 -- The other case for a warning is a reverse loop
2190 -- where the upper bound is the integer literal zero
2191 -- or one, and the lower bound can be positive.
2193 -- For example, we have
2195 -- for J in reverse N .. 1 loop
2197 -- In practice, this is very likely to be a case of
2198 -- reversing the bounds incorrectly in the range.
2200 elsif Reverse_Present (LP)
2201 and then Nkind (Original_Node (H)) =
2203 and then (Intval (Original_Node (H)) = Uint_0
2205 Intval (Original_Node (H)) = Uint_1)
2207 Error_Msg_N ("?loop range may be null", DS);
2208 Error_Msg_N ("\?bounds may be wrong way round", DS);
2215 end Analyze_Iteration_Scheme;
2217 -------------------------------------
2218 -- Analyze_Iterator_Specification --
2219 -------------------------------------
2221 procedure Analyze_Iterator_Specification (N : Node_Id) is
2222 Loc : constant Source_Ptr := Sloc (N);
2223 Def_Id : constant Node_Id := Defining_Identifier (N);
2224 Subt : constant Node_Id := Subtype_Indication (N);
2225 Iter_Name : constant Node_Id := Name (N);
2231 -- In semantics/Alfa modes, we won't be further expanding the loop, so
2232 -- introduce loop variable so that loop body can be properly analyzed.
2233 -- Otherwise this happens after expansion.
2235 if Operating_Mode = Check_Semantics
2238 Enter_Name (Def_Id);
2241 Set_Ekind (Def_Id, E_Variable);
2243 if Present (Subt) then
2247 -- If domain of iteration is an expression, create a declaration for
2248 -- it, so that finalization actions are introduced outside of the loop.
2249 -- The declaration must be a renaming because the body of the loop may
2250 -- assign to elements.
2252 if not Is_Entity_Name (Iter_Name) then
2254 Id : constant Entity_Id := Make_Temporary (Loc, 'R', Iter_Name);
2258 Typ := Etype (Iter_Name);
2260 -- The name in the renaming declaration may be a function call.
2261 -- Indicate that it does not come from source, to suppress
2262 -- spurious warnings on renamings of parameterless functions,
2263 -- a common enough idiom in user-defined iterators.
2266 Make_Object_Renaming_Declaration (Loc,
2267 Defining_Identifier => Id,
2268 Subtype_Mark => New_Occurrence_Of (Typ, Loc),
2270 New_Copy_Tree (Iter_Name, New_Sloc => Loc));
2272 Insert_Actions (Parent (Parent (N)), New_List (Decl));
2273 Rewrite (Name (N), New_Occurrence_Of (Id, Loc));
2274 Set_Etype (Id, Typ);
2275 Set_Etype (Name (N), Typ);
2278 -- Container is an entity or an array with uncontrolled components, or
2279 -- else it is a container iterator given by a function call, typically
2280 -- called Iterate in the case of predefined containers, even though
2281 -- Iterate is not a reserved name. What matter is that the return type
2282 -- of the function is an iterator type.
2285 Analyze (Iter_Name);
2287 if Nkind (Iter_Name) = N_Function_Call then
2289 C : constant Node_Id := Name (Iter_Name);
2294 if not Is_Overloaded (Iter_Name) then
2295 Resolve (Iter_Name, Etype (C));
2298 Get_First_Interp (C, I, It);
2299 while It.Typ /= Empty loop
2300 if Reverse_Present (N) then
2301 if Is_Reversible_Iterator (It.Typ) then
2302 Resolve (Iter_Name, It.Typ);
2306 elsif Is_Iterator (It.Typ) then
2307 Resolve (Iter_Name, It.Typ);
2311 Get_Next_Interp (I, It);
2316 -- Domain of iteration is not overloaded
2319 Resolve (Iter_Name, Etype (Iter_Name));
2323 Typ := Etype (Iter_Name);
2325 if Is_Array_Type (Typ) then
2326 if Of_Present (N) then
2327 Set_Etype (Def_Id, Component_Type (Typ));
2329 -- Here we have a missing Range attribute
2333 ("missing Range attribute in iteration over an array", N);
2335 -- In Ada 2012 mode, this may be an attempt at an iterator
2337 if Ada_Version >= Ada_2012 then
2339 ("\if& is meant to designate an element of the array, use OF",
2343 -- Prevent cascaded errors
2345 Set_Ekind (Def_Id, E_Loop_Parameter);
2346 Set_Etype (Def_Id, Etype (First_Index (Typ)));
2349 -- Check for type error in iterator
2351 elsif Typ = Any_Type then
2354 -- Iteration over a container
2357 Set_Ekind (Def_Id, E_Loop_Parameter);
2359 if Of_Present (N) then
2361 -- The type of the loop variable is the Iterator_Element aspect of
2362 -- the container type.
2365 Element : constant Entity_Id :=
2366 Find_Aspect (Typ, Aspect_Iterator_Element);
2368 if No (Element) then
2369 Error_Msg_NE ("cannot iterate over&", N, Typ);
2372 Set_Etype (Def_Id, Entity (Element));
2377 -- For an iteration of the form IN, the name must denote an
2378 -- iterator, typically the result of a call to Iterate. Give a
2379 -- useful error message when the name is a container by itself.
2381 if Is_Entity_Name (Original_Node (Name (N)))
2382 and then not Is_Iterator (Typ)
2384 if No (Find_Aspect (Typ, Aspect_Iterator_Element)) then
2386 ("cannot iterate over&", Name (N), Typ);
2389 ("name must be an iterator, not a container", Name (N));
2393 ("\to iterate directly over the elements of a container, " &
2394 "write `of &`", Name (N), Original_Node (Name (N)));
2397 -- The result type of Iterate function is the classwide type of
2398 -- the interface parent. We need the specific Cursor type defined
2399 -- in the container package.
2401 Ent := First_Entity (Scope (Typ));
2402 while Present (Ent) loop
2403 if Chars (Ent) = Name_Cursor then
2404 Set_Etype (Def_Id, Etype (Ent));
2412 end Analyze_Iterator_Specification;
2418 -- Note: the semantic work required for analyzing labels (setting them as
2419 -- reachable) was done in a prepass through the statements in the block,
2420 -- so that forward gotos would be properly handled. See Analyze_Statements
2421 -- for further details. The only processing required here is to deal with
2422 -- optimizations that depend on an assumption of sequential control flow,
2423 -- since of course the occurrence of a label breaks this assumption.
2425 procedure Analyze_Label (N : Node_Id) is
2426 pragma Warnings (Off, N);
2428 Kill_Current_Values;
2431 --------------------------
2432 -- Analyze_Label_Entity --
2433 --------------------------
2435 procedure Analyze_Label_Entity (E : Entity_Id) is
2437 Set_Ekind (E, E_Label);
2438 Set_Etype (E, Standard_Void_Type);
2439 Set_Enclosing_Scope (E, Current_Scope);
2440 Set_Reachable (E, True);
2441 end Analyze_Label_Entity;
2443 ----------------------------
2444 -- Analyze_Loop_Statement --
2445 ----------------------------
2447 procedure Analyze_Loop_Statement (N : Node_Id) is
2449 function Is_Container_Iterator (Iter : Node_Id) return Boolean;
2450 -- Given a loop iteration scheme, determine whether it is an Ada 2012
2451 -- container iteration.
2453 function Is_Wrapped_In_Block (N : Node_Id) return Boolean;
2454 -- Determine whether node N is the sole statement of a block
2456 ---------------------------
2457 -- Is_Container_Iterator --
2458 ---------------------------
2460 function Is_Container_Iterator (Iter : Node_Id) return Boolean is
2469 elsif Present (Condition (Iter)) then
2472 -- for Def_Id in [reverse] Name loop
2473 -- for Def_Id [: Subtype_Indication] of [reverse] Name loop
2475 elsif Present (Iterator_Specification (Iter)) then
2477 Nam : constant Node_Id := Name (Iterator_Specification (Iter));
2481 Nam_Copy := New_Copy_Tree (Nam);
2482 Set_Parent (Nam_Copy, Parent (Nam));
2483 Pre_Analyze_Range (Nam_Copy);
2485 -- The only two options here are iteration over a container or
2488 return not Is_Array_Type (Etype (Nam_Copy));
2491 -- for Def_Id in [reverse] Discrete_Subtype_Definition loop
2495 LP : constant Node_Id := Loop_Parameter_Specification (Iter);
2496 DS : constant Node_Id := Discrete_Subtype_Definition (LP);
2500 DS_Copy := New_Copy_Tree (DS);
2501 Set_Parent (DS_Copy, Parent (DS));
2502 Pre_Analyze_Range (DS_Copy);
2504 -- Check for a call to Iterate ()
2507 Nkind (DS_Copy) = N_Function_Call
2508 and then Needs_Finalization (Etype (DS_Copy));
2511 end Is_Container_Iterator;
2513 -------------------------
2514 -- Is_Wrapped_In_Block --
2515 -------------------------
2517 function Is_Wrapped_In_Block (N : Node_Id) return Boolean is
2518 HSS : constant Node_Id := Parent (N);
2522 Nkind (HSS) = N_Handled_Sequence_Of_Statements
2523 and then Nkind (Parent (HSS)) = N_Block_Statement
2524 and then First (Statements (HSS)) = N
2525 and then No (Next (First (Statements (HSS))));
2526 end Is_Wrapped_In_Block;
2528 -- Local declarations
2530 Id : constant Node_Id := Identifier (N);
2531 Iter : constant Node_Id := Iteration_Scheme (N);
2532 Loc : constant Source_Ptr := Sloc (N);
2535 -- Start of processing for Analyze_Loop_Statement
2538 if Present (Id) then
2540 -- Make name visible, e.g. for use in exit statements. Loop labels
2541 -- are always considered to be referenced.
2546 -- Guard against serious error (typically, a scope mismatch when
2547 -- semantic analysis is requested) by creating loop entity to
2548 -- continue analysis.
2551 if Total_Errors_Detected /= 0 then
2552 Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
2554 raise Program_Error;
2558 Generate_Reference (Ent, N, ' ');
2559 Generate_Definition (Ent);
2561 -- If we found a label, mark its type. If not, ignore it, since it
2562 -- means we have a conflicting declaration, which would already
2563 -- have been diagnosed at declaration time. Set Label_Construct
2564 -- of the implicit label declaration, which is not created by the
2565 -- parser for generic units.
2567 if Ekind (Ent) = E_Label then
2568 Set_Ekind (Ent, E_Loop);
2570 if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
2571 Set_Label_Construct (Parent (Ent), N);
2576 -- Case of no identifier present
2579 Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
2580 Set_Etype (Ent, Standard_Void_Type);
2581 Set_Parent (Ent, N);
2584 -- Iteration over a container in Ada 2012 involves the creation of a
2585 -- controlled iterator object. Wrap the loop in a block to ensure the
2586 -- timely finalization of the iterator and release of container locks.
2588 if Ada_Version >= Ada_2012
2589 and then Is_Container_Iterator (Iter)
2590 and then not Is_Wrapped_In_Block (N)
2593 Make_Block_Statement (Loc,
2594 Declarations => New_List,
2595 Handled_Statement_Sequence =>
2596 Make_Handled_Sequence_Of_Statements (Loc,
2597 Statements => New_List (Relocate_Node (N)))));
2603 -- Kill current values on entry to loop, since statements in the body of
2604 -- the loop may have been executed before the loop is entered. Similarly
2605 -- we kill values after the loop, since we do not know that the body of
2606 -- the loop was executed.
2608 Kill_Current_Values;
2610 Analyze_Iteration_Scheme (Iter);
2612 -- Analyze the statements of the body except in the case of an Ada 2012
2613 -- iterator with the expander active. In this case the expander will do
2614 -- a rewrite of the loop into a while loop. We will then analyze the
2615 -- loop body when we analyze this while loop.
2617 -- We need to do this delay because if the container is for indefinite
2618 -- types the actual subtype of the components will only be determined
2619 -- when the cursor declaration is analyzed.
2621 -- If the expander is not active, then we want to analyze the loop body
2622 -- now even in the Ada 2012 iterator case, since the rewriting will not
2623 -- be done. Insert the loop variable in the current scope, if not done
2624 -- when analysing the iteration scheme.
2627 or else No (Iterator_Specification (Iter))
2628 or else not Expander_Active
2631 and then Present (Iterator_Specification (Iter))
2634 Id : constant Entity_Id :=
2635 Defining_Identifier (Iterator_Specification (Iter));
2637 if Scope (Id) /= Current_Scope then
2643 Analyze_Statements (Statements (N));
2646 -- Finish up processing for the loop. We kill all current values, since
2647 -- in general we don't know if the statements in the loop have been
2648 -- executed. We could do a bit better than this with a loop that we
2649 -- know will execute at least once, but it's not worth the trouble and
2650 -- the front end is not in the business of flow tracing.
2652 Process_End_Label (N, 'e', Ent);
2654 Kill_Current_Values;
2656 -- Check for infinite loop. Skip check for generated code, since it
2657 -- justs waste time and makes debugging the routine called harder.
2659 -- Note that we have to wait till the body of the loop is fully analyzed
2660 -- before making this call, since Check_Infinite_Loop_Warning relies on
2661 -- being able to use semantic visibility information to find references.
2663 if Comes_From_Source (N) then
2664 Check_Infinite_Loop_Warning (N);
2667 -- Code after loop is unreachable if the loop has no WHILE or FOR and
2668 -- contains no EXIT statements within the body of the loop.
2670 if No (Iter) and then not Has_Exit (Ent) then
2671 Check_Unreachable_Code (N);
2673 end Analyze_Loop_Statement;
2675 ----------------------------
2676 -- Analyze_Null_Statement --
2677 ----------------------------
2679 -- Note: the semantics of the null statement is implemented by a single
2680 -- null statement, too bad everything isn't as simple as this!
2682 procedure Analyze_Null_Statement (N : Node_Id) is
2683 pragma Warnings (Off, N);
2686 end Analyze_Null_Statement;
2688 ------------------------
2689 -- Analyze_Statements --
2690 ------------------------
2692 procedure Analyze_Statements (L : List_Id) is
2697 -- The labels declared in the statement list are reachable from
2698 -- statements in the list. We do this as a prepass so that any goto
2699 -- statement will be properly flagged if its target is not reachable.
2700 -- This is not required, but is nice behavior!
2703 while Present (S) loop
2704 if Nkind (S) = N_Label then
2705 Analyze (Identifier (S));
2706 Lab := Entity (Identifier (S));
2708 -- If we found a label mark it as reachable
2710 if Ekind (Lab) = E_Label then
2711 Generate_Definition (Lab);
2712 Set_Reachable (Lab);
2714 if Nkind (Parent (Lab)) = N_Implicit_Label_Declaration then
2715 Set_Label_Construct (Parent (Lab), S);
2718 -- If we failed to find a label, it means the implicit declaration
2719 -- of the label was hidden. A for-loop parameter can do this to
2720 -- a label with the same name inside the loop, since the implicit
2721 -- label declaration is in the innermost enclosing body or block
2725 Error_Msg_Sloc := Sloc (Lab);
2727 ("implicit label declaration for & is hidden#",
2735 -- Perform semantic analysis on all statements
2737 Conditional_Statements_Begin;
2740 while Present (S) loop
2743 -- Remove dimension in all statements
2745 Remove_Dimension_In_Statement (S);
2749 Conditional_Statements_End;
2751 -- Make labels unreachable. Visibility is not sufficient, because labels
2752 -- in one if-branch for example are not reachable from the other branch,
2753 -- even though their declarations are in the enclosing declarative part.
2756 while Present (S) loop
2757 if Nkind (S) = N_Label then
2758 Set_Reachable (Entity (Identifier (S)), False);
2763 end Analyze_Statements;
2765 ----------------------------
2766 -- Check_Unreachable_Code --
2767 ----------------------------
2769 procedure Check_Unreachable_Code (N : Node_Id) is
2770 Error_Node : Node_Id;
2774 if Is_List_Member (N)
2775 and then Comes_From_Source (N)
2781 Nxt := Original_Node (Next (N));
2783 -- If a label follows us, then we never have dead code, since
2784 -- someone could branch to the label, so we just ignore it, unless
2785 -- we are in formal mode where goto statements are not allowed.
2787 if Nkind (Nxt) = N_Label
2788 and then not Restriction_Check_Required (SPARK)
2792 -- Otherwise see if we have a real statement following us
2795 and then Comes_From_Source (Nxt)
2796 and then Is_Statement (Nxt)
2798 -- Special very annoying exception. If we have a return that
2799 -- follows a raise, then we allow it without a warning, since
2800 -- the Ada RM annoyingly requires a useless return here!
2802 if Nkind (Original_Node (N)) /= N_Raise_Statement
2803 or else Nkind (Nxt) /= N_Simple_Return_Statement
2805 -- The rather strange shenanigans with the warning message
2806 -- here reflects the fact that Kill_Dead_Code is very good
2807 -- at removing warnings in deleted code, and this is one
2808 -- warning we would prefer NOT to have removed.
2812 -- If we have unreachable code, analyze and remove the
2813 -- unreachable code, since it is useless and we don't
2814 -- want to generate junk warnings.
2816 -- We skip this step if we are not in code generation mode.
2817 -- This is the one case where we remove dead code in the
2818 -- semantics as opposed to the expander, and we do not want
2819 -- to remove code if we are not in code generation mode,
2820 -- since this messes up the ASIS trees.
2822 -- Note that one might react by moving the whole circuit to
2823 -- exp_ch5, but then we lose the warning in -gnatc mode.
2825 if Operating_Mode = Generate_Code then
2829 -- Quit deleting when we have nothing more to delete
2830 -- or if we hit a label (since someone could transfer
2831 -- control to a label, so we should not delete it).
2833 exit when No (Nxt) or else Nkind (Nxt) = N_Label;
2835 -- Statement/declaration is to be deleted
2839 Kill_Dead_Code (Nxt);
2843 -- Now issue the warning (or error in formal mode)
2845 if Restriction_Check_Required (SPARK) then
2846 Check_SPARK_Restriction
2847 ("unreachable code is not allowed", Error_Node);
2849 Error_Msg ("?unreachable code!", Sloc (Error_Node));
2853 -- If the unconditional transfer of control instruction is the
2854 -- last statement of a sequence, then see if our parent is one of
2855 -- the constructs for which we count unblocked exits, and if so,
2856 -- adjust the count.
2861 -- Statements in THEN part or ELSE part of IF statement
2863 if Nkind (P) = N_If_Statement then
2866 -- Statements in ELSIF part of an IF statement
2868 elsif Nkind (P) = N_Elsif_Part then
2870 pragma Assert (Nkind (P) = N_If_Statement);
2872 -- Statements in CASE statement alternative
2874 elsif Nkind (P) = N_Case_Statement_Alternative then
2876 pragma Assert (Nkind (P) = N_Case_Statement);
2878 -- Statements in body of block
2880 elsif Nkind (P) = N_Handled_Sequence_Of_Statements
2881 and then Nkind (Parent (P)) = N_Block_Statement
2885 -- Statements in exception handler in a block
2887 elsif Nkind (P) = N_Exception_Handler
2888 and then Nkind (Parent (P)) = N_Handled_Sequence_Of_Statements
2889 and then Nkind (Parent (Parent (P))) = N_Block_Statement
2893 -- None of these cases, so return
2899 -- This was one of the cases we are looking for (i.e. the
2900 -- parent construct was IF, CASE or block) so decrement count.
2902 Unblocked_Exit_Count := Unblocked_Exit_Count - 1;
2906 end Check_Unreachable_Code;
2908 -----------------------
2909 -- Pre_Analyze_Range --
2910 -----------------------
2912 procedure Pre_Analyze_Range (R_Copy : Node_Id) is
2913 Save_Analysis : constant Boolean := Full_Analysis;
2916 Full_Analysis := False;
2917 Expander_Mode_Save_And_Set (False);
2921 if Nkind (R_Copy) in N_Subexpr
2922 and then Is_Overloaded (R_Copy)
2924 -- Apply preference rules for range of predefined integer types, or
2925 -- diagnose true ambiguity.
2930 Found : Entity_Id := Empty;
2933 Get_First_Interp (R_Copy, I, It);
2934 while Present (It.Typ) loop
2935 if Is_Discrete_Type (It.Typ) then
2939 if Scope (Found) = Standard_Standard then
2942 elsif Scope (It.Typ) = Standard_Standard then
2946 -- Both of them are user-defined
2949 ("ambiguous bounds in range of iteration", R_Copy);
2950 Error_Msg_N ("\possible interpretations:", R_Copy);
2951 Error_Msg_NE ("\\} ", R_Copy, Found);
2952 Error_Msg_NE ("\\} ", R_Copy, It.Typ);
2958 Get_Next_Interp (I, It);
2963 -- Subtype mark in iteration scheme
2965 if Is_Entity_Name (R_Copy)
2966 and then Is_Type (Entity (R_Copy))
2970 -- Expression in range, or Ada 2012 iterator
2972 elsif Nkind (R_Copy) in N_Subexpr then
2976 Expander_Mode_Restore;
2977 Full_Analysis := Save_Analysis;
2978 end Pre_Analyze_Range;