1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2004 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 2, 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 COPYING. If not, write --
19 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
20 -- MA 02111-1307, USA. --
22 -- GNAT was originally developed by the GNAT team at New York University. --
23 -- Extensive contributions were provided by Ada Core Technologies Inc. --
25 ------------------------------------------------------------------------------
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_Util; use Exp_Util;
33 with Freeze; use Freeze;
34 with Lib.Xref; use Lib.Xref;
35 with Nlists; use Nlists;
36 with Nmake; use Nmake;
39 with Sem_Case; use Sem_Case;
40 with Sem_Ch3; use Sem_Ch3;
41 with Sem_Ch8; use Sem_Ch8;
42 with Sem_Disp; use Sem_Disp;
43 with Sem_Eval; use Sem_Eval;
44 with Sem_Res; use Sem_Res;
45 with Sem_Type; use Sem_Type;
46 with Sem_Util; use Sem_Util;
47 with Sem_Warn; use Sem_Warn;
48 with Stand; use Stand;
49 with Sinfo; use Sinfo;
50 with Targparm; use Targparm;
51 with Tbuild; use Tbuild;
52 with Uintp; use Uintp;
54 package body Sem_Ch5 is
56 Unblocked_Exit_Count : Nat := 0;
57 -- This variable is used when processing if statements, case statements,
58 -- and block statements. It counts the number of exit points that are
59 -- not blocked by unconditional transfer instructions (for IF and CASE,
60 -- these are the branches of the conditional, for a block, they are the
61 -- statement sequence of the block, and the statement sequences of any
62 -- exception handlers that are part of the block. When processing is
63 -- complete, if this count is zero, it means that control cannot fall
64 -- through the IF, CASE or block statement. This is used for the
65 -- generation of warning messages. This variable is recursively saved
66 -- on entry to processing the construct, and restored on exit.
68 -----------------------
69 -- Local Subprograms --
70 -----------------------
72 procedure Analyze_Iteration_Scheme (N : Node_Id);
74 procedure Check_Possible_Current_Value_Condition (Cnode : Node_Id);
75 -- Cnode is N_If_Statement, N_Elsif_Part, or N_Iteration_Scheme
76 -- (the latter when a WHILE condition is present). This call checks
77 -- if Condition (Cnode) is of the form ([NOT] var op val), where var
78 -- is a simple object, val is known at compile time, and op is one
79 -- of the six relational operators. If this is the case, and the
80 -- Current_Value field of "var" is not set, then it is set to Cnode.
81 -- See Exp_Util.Set_Current_Value_Condition for further details.
83 ------------------------
84 -- Analyze_Assignment --
85 ------------------------
87 procedure Analyze_Assignment (N : Node_Id) is
88 Lhs : constant Node_Id := Name (N);
89 Rhs : constant Node_Id := Expression (N);
95 procedure Diagnose_Non_Variable_Lhs (N : Node_Id);
96 -- N is the node for the left hand side of an assignment, and it
97 -- is not a variable. This routine issues an appropriate diagnostic.
99 procedure Set_Assignment_Type
101 Opnd_Type : in out Entity_Id);
102 -- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type
103 -- is the nominal subtype. This procedure is used to deal with cases
104 -- where the nominal subtype must be replaced by the actual subtype.
106 -------------------------------
107 -- Diagnose_Non_Variable_Lhs --
108 -------------------------------
110 procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is
112 -- Not worth posting another error if left hand side already
113 -- flagged as being illegal in some respect
115 if Error_Posted (N) then
118 -- Some special bad cases of entity names
120 elsif Is_Entity_Name (N) then
121 if Ekind (Entity (N)) = E_In_Parameter then
123 ("assignment to IN mode parameter not allowed", N);
125 -- Private declarations in a protected object are turned into
126 -- constants when compiling a protected function.
128 elsif Present (Scope (Entity (N)))
129 and then Is_Protected_Type (Scope (Entity (N)))
131 (Ekind (Current_Scope) = E_Function
133 Ekind (Enclosing_Dynamic_Scope (Current_Scope)) = E_Function)
136 ("protected function cannot modify protected object", N);
138 elsif Ekind (Entity (N)) = E_Loop_Parameter then
140 ("assignment to loop parameter not allowed", N);
144 ("left hand side of assignment must be a variable", N);
147 -- For indexed components or selected components, test prefix
149 elsif Nkind (N) = N_Indexed_Component then
150 Diagnose_Non_Variable_Lhs (Prefix (N));
152 -- Another special case for assignment to discriminant.
154 elsif Nkind (N) = N_Selected_Component then
155 if Present (Entity (Selector_Name (N)))
156 and then Ekind (Entity (Selector_Name (N))) = E_Discriminant
159 ("assignment to discriminant not allowed", N);
161 Diagnose_Non_Variable_Lhs (Prefix (N));
165 -- If we fall through, we have no special message to issue!
167 Error_Msg_N ("left hand side of assignment must be a variable", N);
169 end Diagnose_Non_Variable_Lhs;
171 -------------------------
172 -- Set_Assignment_Type --
173 -------------------------
175 procedure Set_Assignment_Type
177 Opnd_Type : in out Entity_Id)
180 Require_Entity (Opnd);
182 -- If the assignment operand is an in-out or out parameter, then we
183 -- get the actual subtype (needed for the unconstrained case).
184 -- If the operand is the actual in an entry declaration, then within
185 -- the accept statement it is replaced with a local renaming, which
186 -- may also have an actual subtype.
188 if Is_Entity_Name (Opnd)
189 and then (Ekind (Entity (Opnd)) = E_Out_Parameter
190 or else Ekind (Entity (Opnd)) =
192 or else Ekind (Entity (Opnd)) =
193 E_Generic_In_Out_Parameter
195 (Ekind (Entity (Opnd)) = E_Variable
196 and then Nkind (Parent (Entity (Opnd))) =
197 N_Object_Renaming_Declaration
198 and then Nkind (Parent (Parent (Entity (Opnd)))) =
201 Opnd_Type := Get_Actual_Subtype (Opnd);
203 -- If assignment operand is a component reference, then we get the
204 -- actual subtype of the component for the unconstrained case.
207 (Nkind (Opnd) = N_Selected_Component
208 or else Nkind (Opnd) = N_Explicit_Dereference)
209 and then not Is_Unchecked_Union (Opnd_Type)
211 Decl := Build_Actual_Subtype_Of_Component (Opnd_Type, Opnd);
213 if Present (Decl) then
214 Insert_Action (N, Decl);
215 Mark_Rewrite_Insertion (Decl);
217 Opnd_Type := Defining_Identifier (Decl);
218 Set_Etype (Opnd, Opnd_Type);
219 Freeze_Itype (Opnd_Type, N);
221 elsif Is_Constrained (Etype (Opnd)) then
222 Opnd_Type := Etype (Opnd);
225 -- For slice, use the constrained subtype created for the slice
227 elsif Nkind (Opnd) = N_Slice then
228 Opnd_Type := Etype (Opnd);
230 end Set_Assignment_Type;
232 -- Start of processing for Analyze_Assignment
239 -- In the most general case, both Lhs and Rhs can be overloaded, and we
240 -- must compute the intersection of the possible types on each side.
242 if Is_Overloaded (Lhs) then
249 Get_First_Interp (Lhs, I, It);
251 while Present (It.Typ) loop
252 if Has_Compatible_Type (Rhs, It.Typ) then
253 if T1 /= Any_Type then
255 -- An explicit dereference is overloaded if the prefix
256 -- is. Try to remove the ambiguity on the prefix, the
257 -- error will be posted there if the ambiguity is real.
259 if Nkind (Lhs) = N_Explicit_Dereference then
262 PI1 : Interp_Index := 0;
268 Get_First_Interp (Prefix (Lhs), PI, PIt);
270 while Present (PIt.Typ) loop
271 if Is_Access_Type (PIt.Typ)
272 and then Has_Compatible_Type
273 (Rhs, Designated_Type (PIt.Typ))
277 Disambiguate (Prefix (Lhs),
280 if PIt = No_Interp then
282 ("ambiguous left-hand side"
283 & " in assignment", Lhs);
286 Resolve (Prefix (Lhs), PIt.Typ);
296 Get_Next_Interp (PI, PIt);
302 ("ambiguous left-hand side in assignment", Lhs);
310 Get_Next_Interp (I, It);
314 if T1 = Any_Type then
316 ("no valid types for left-hand side for assignment", Lhs);
323 if not Is_Variable (Lhs) then
324 Diagnose_Non_Variable_Lhs (Lhs);
327 elsif Is_Limited_Type (T1)
328 and then not Assignment_OK (Lhs)
329 and then not Assignment_OK (Original_Node (Lhs))
332 ("left hand of assignment must not be limited type", Lhs);
333 Explain_Limited_Type (T1, Lhs);
337 -- Resolution may have updated the subtype, in case the left-hand
338 -- side is a private protected component. Use the correct subtype
339 -- to avoid scoping issues in the back-end.
342 Set_Assignment_Type (Lhs, T1);
345 Check_Unset_Reference (Rhs);
347 -- Remaining steps are skipped if Rhs was syntactically in error
355 if Covers (T1, T2) then
358 Wrong_Type (Rhs, Etype (Lhs));
362 Set_Assignment_Type (Rhs, T2);
364 if Total_Errors_Detected /= 0 then
374 if T1 = Any_Type or else T2 = Any_Type then
378 if (Is_Class_Wide_Type (T2) or else Is_Dynamically_Tagged (Rhs))
379 and then not Is_Class_Wide_Type (T1)
381 Error_Msg_N ("dynamically tagged expression not allowed!", Rhs);
383 elsif Is_Class_Wide_Type (T1)
384 and then not Is_Class_Wide_Type (T2)
385 and then not Is_Tag_Indeterminate (Rhs)
386 and then not Is_Dynamically_Tagged (Rhs)
388 Error_Msg_N ("dynamically tagged expression required!", Rhs);
391 -- Tag propagation is done only in semantics mode only. If expansion
392 -- is on, the rhs tag indeterminate function call has been expanded
393 -- and tag propagation would have happened too late, so the
394 -- propagation take place in expand_call instead.
396 if not Expander_Active
397 and then Is_Class_Wide_Type (T1)
398 and then Is_Tag_Indeterminate (Rhs)
400 Propagate_Tag (Lhs, Rhs);
405 if Ada_Version >= Ada_05
406 and then Nkind (Rhs) = N_Null
407 and then Is_Access_Type (T1)
408 and then not Assignment_OK (Lhs)
409 and then ((Is_Entity_Name (Lhs)
410 and then Can_Never_Be_Null (Entity (Lhs)))
411 or else Can_Never_Be_Null (Etype (Lhs)))
414 ("(Ada 2005) NULL not allowed in null-excluding objects", Lhs);
417 if Is_Scalar_Type (T1) then
418 Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
420 elsif Is_Array_Type (T1)
422 (Nkind (Rhs) /= N_Type_Conversion
423 or else Is_Constrained (Etype (Rhs)))
425 -- Assignment verifies that the length of the Lsh and Rhs are equal,
426 -- but of course the indices do not have to match. If the right-hand
427 -- side is a type conversion to an unconstrained type, a length check
428 -- is performed on the expression itself during expansion. In rare
429 -- cases, the redundant length check is computed on an index type
430 -- with a different representation, triggering incorrect code in
433 Apply_Length_Check (Rhs, Etype (Lhs));
436 -- Discriminant checks are applied in the course of expansion
441 -- Note: modifications of the Lhs may only be recorded after
442 -- checks have been applied.
444 Note_Possible_Modification (Lhs);
446 -- ??? a real accessibility check is needed when ???
448 -- Post warning for useless assignment
450 if Warn_On_Redundant_Constructs
452 -- We only warn for source constructs
454 and then Comes_From_Source (N)
456 -- Where the entity is the same on both sides
458 and then Is_Entity_Name (Lhs)
459 and then Is_Entity_Name (Original_Node (Rhs))
460 and then Entity (Lhs) = Entity (Original_Node (Rhs))
462 -- But exclude the case where the right side was an operation
463 -- that got rewritten (e.g. JUNK + K, where K was known to be
464 -- zero). We don't want to warn in such a case, since it is
465 -- reasonable to write such expressions especially when K is
466 -- defined symbolically in some other package.
468 and then Nkind (Original_Node (Rhs)) not in N_Op
471 ("?useless assignment of & to itself", N, Entity (Lhs));
474 -- Check for non-allowed composite assignment
476 if not Support_Composite_Assign_On_Target
477 and then (Is_Array_Type (T1) or else Is_Record_Type (T1))
478 and then (not Has_Size_Clause (T1) or else Esize (T1) > 64)
480 Error_Msg_CRT ("composite assignment", N);
483 -- One more step. Let's see if we have a simple assignment of a
484 -- known at compile time value to a simple variable. If so, we
485 -- can record the value as the current value providing that:
487 -- We still have a simple assignment statement (no expansion
488 -- activity has modified it in some peculiar manner)
490 -- The type is a discrete type
492 -- The assignment is to a named entity
494 -- The value is known at compile time
496 if Nkind (N) /= N_Assignment_Statement
497 or else not Is_Discrete_Type (T1)
498 or else not Is_Entity_Name (Lhs)
499 or else not Compile_Time_Known_Value (Rhs)
506 -- Capture value if save to do so
508 if Safe_To_Capture_Value (N, Ent) then
509 Set_Current_Value (Ent, Rhs);
511 end Analyze_Assignment;
513 -----------------------------
514 -- Analyze_Block_Statement --
515 -----------------------------
517 procedure Analyze_Block_Statement (N : Node_Id) is
518 Decls : constant List_Id := Declarations (N);
519 Id : constant Node_Id := Identifier (N);
520 HSS : constant Node_Id := Handled_Statement_Sequence (N);
523 -- If no handled statement sequence is present, things are really
524 -- messed up, and we just return immediately (this is a defence
525 -- against previous errors).
531 -- Normal processing with HSS present
534 EH : constant List_Id := Exception_Handlers (HSS);
535 Ent : Entity_Id := Empty;
538 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
539 -- Recursively save value of this global, will be restored on exit
542 -- Initialize unblocked exit count for statements of begin block
543 -- plus one for each excption handler that is present.
545 Unblocked_Exit_Count := 1;
548 Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH);
551 -- If a label is present analyze it and mark it as referenced
557 -- An error defense. If we have an identifier, but no entity,
558 -- then something is wrong. If we have previous errors, then
559 -- just remove the identifier and continue, otherwise raise
563 if Total_Errors_Detected /= 0 then
564 Set_Identifier (N, Empty);
570 Set_Ekind (Ent, E_Block);
571 Generate_Reference (Ent, N, ' ');
572 Generate_Definition (Ent);
574 if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
575 Set_Label_Construct (Parent (Ent), N);
580 -- If no entity set, create a label entity
583 Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B');
584 Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N)));
588 Set_Etype (Ent, Standard_Void_Type);
589 Set_Block_Node (Ent, Identifier (N));
592 if Present (Decls) then
593 Analyze_Declarations (Decls);
598 Process_End_Label (HSS, 'e', Ent);
600 -- If exception handlers are present, then we indicate that
601 -- enclosing scopes contain a block with handlers. We only
602 -- need to mark non-generic scopes.
607 Set_Has_Nested_Block_With_Handler (S);
608 exit when Is_Overloadable (S)
609 or else Ekind (S) = E_Package
610 or else Is_Generic_Unit (S);
615 Check_References (Ent);
618 if Unblocked_Exit_Count = 0 then
619 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
620 Check_Unreachable_Code (N);
622 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
625 end Analyze_Block_Statement;
627 ----------------------------
628 -- Analyze_Case_Statement --
629 ----------------------------
631 procedure Analyze_Case_Statement (N : Node_Id) is
633 Exp_Type : Entity_Id;
634 Exp_Btype : Entity_Id;
637 Others_Present : Boolean;
639 Statements_Analyzed : Boolean := False;
640 -- Set True if at least some statement sequences get analyzed.
641 -- If False on exit, means we had a serious error that prevented
642 -- full analysis of the case statement, and as a result it is not
643 -- a good idea to output warning messages about unreachable code.
645 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
646 -- Recursively save value of this global, will be restored on exit
648 procedure Non_Static_Choice_Error (Choice : Node_Id);
649 -- Error routine invoked by the generic instantiation below when
650 -- the case statment has a non static choice.
652 procedure Process_Statements (Alternative : Node_Id);
653 -- Analyzes all the statements associated to a case alternative.
654 -- Needed by the generic instantiation below.
656 package Case_Choices_Processing is new
657 Generic_Choices_Processing
658 (Get_Alternatives => Alternatives,
659 Get_Choices => Discrete_Choices,
660 Process_Empty_Choice => No_OP,
661 Process_Non_Static_Choice => Non_Static_Choice_Error,
662 Process_Associated_Node => Process_Statements);
663 use Case_Choices_Processing;
664 -- Instantiation of the generic choice processing package
666 -----------------------------
667 -- Non_Static_Choice_Error --
668 -----------------------------
670 procedure Non_Static_Choice_Error (Choice : Node_Id) is
673 ("choice given in case statement is not static!", Choice);
674 end Non_Static_Choice_Error;
676 ------------------------
677 -- Process_Statements --
678 ------------------------
680 procedure Process_Statements (Alternative : Node_Id) is
681 Choices : constant List_Id := Discrete_Choices (Alternative);
685 Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
686 Statements_Analyzed := True;
688 -- An interesting optimization. If the case statement expression
689 -- is a simple entity, then we can set the current value within
690 -- an alternative if the alternative has one possible value.
694 -- when 2 | 3 => beta
695 -- when others => gamma
697 -- Here we know that N is initially 1 within alpha, but for beta
698 -- and gamma, we do not know anything more about the initial value.
700 if Is_Entity_Name (Exp) then
703 if Ekind (Ent) = E_Variable
705 Ekind (Ent) = E_In_Out_Parameter
707 Ekind (Ent) = E_Out_Parameter
709 if List_Length (Choices) = 1
710 and then Nkind (First (Choices)) in N_Subexpr
711 and then Compile_Time_Known_Value (First (Choices))
713 Set_Current_Value (Entity (Exp), First (Choices));
716 Analyze_Statements (Statements (Alternative));
718 -- After analyzing the case, set the current value to empty
719 -- since we won't know what it is for the next alternative
720 -- (unless reset by this same circuit), or after the case.
722 Set_Current_Value (Entity (Exp), Empty);
727 -- Case where expression is not an entity name of a variable
729 Analyze_Statements (Statements (Alternative));
730 end Process_Statements;
732 -- Table to record choices. Put after subprograms since we make
733 -- a call to Number_Of_Choices to get the right number of entries.
735 Case_Table : Choice_Table_Type (1 .. Number_Of_Choices (N));
737 -- Start of processing for Analyze_Case_Statement
740 Unblocked_Exit_Count := 0;
741 Exp := Expression (N);
742 Analyze_And_Resolve (Exp, Any_Discrete);
743 Check_Unset_Reference (Exp);
744 Exp_Type := Etype (Exp);
745 Exp_Btype := Base_Type (Exp_Type);
747 -- The expression must be of a discrete type which must be determinable
748 -- independently of the context in which the expression occurs, but
749 -- using the fact that the expression must be of a discrete type.
750 -- Moreover, the type this expression must not be a character literal
751 -- (which is always ambiguous) or, for Ada-83, a generic formal type.
753 -- If error already reported by Resolve, nothing more to do
755 if Exp_Btype = Any_Discrete
756 or else Exp_Btype = Any_Type
760 elsif Exp_Btype = Any_Character then
762 ("character literal as case expression is ambiguous", Exp);
765 elsif Ada_Version = Ada_83
766 and then (Is_Generic_Type (Exp_Btype)
767 or else Is_Generic_Type (Root_Type (Exp_Btype)))
770 ("(Ada 83) case expression cannot be of a generic type", Exp);
774 -- If the case expression is a formal object of mode in out, then
775 -- treat it as having a nonstatic subtype by forcing use of the base
776 -- type (which has to get passed to Check_Case_Choices below). Also
777 -- use base type when the case expression is parenthesized.
779 if Paren_Count (Exp) > 0
780 or else (Is_Entity_Name (Exp)
781 and then Ekind (Entity (Exp)) = E_Generic_In_Out_Parameter)
783 Exp_Type := Exp_Btype;
786 -- Call instantiated Analyze_Choices which does the rest of the work
789 (N, Exp_Type, Case_Table, Last_Choice, Dont_Care, Others_Present);
791 if Exp_Type = Universal_Integer and then not Others_Present then
792 Error_Msg_N ("case on universal integer requires OTHERS choice", Exp);
795 -- If all our exits were blocked by unconditional transfers of control,
796 -- then the entire CASE statement acts as an unconditional transfer of
797 -- control, so treat it like one, and check unreachable code. Skip this
798 -- test if we had serious errors preventing any statement analysis.
800 if Unblocked_Exit_Count = 0 and then Statements_Analyzed then
801 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
802 Check_Unreachable_Code (N);
804 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
807 if not Expander_Active
808 and then Compile_Time_Known_Value (Expression (N))
809 and then Serious_Errors_Detected = 0
812 Chosen : constant Node_Id := Find_Static_Alternative (N);
816 Alt := First (Alternatives (N));
818 while Present (Alt) loop
819 if Alt /= Chosen then
820 Remove_Warning_Messages (Statements (Alt));
827 end Analyze_Case_Statement;
829 ----------------------------
830 -- Analyze_Exit_Statement --
831 ----------------------------
833 -- If the exit includes a name, it must be the name of a currently open
834 -- loop. Otherwise there must be an innermost open loop on the stack,
835 -- to which the statement implicitly refers.
837 procedure Analyze_Exit_Statement (N : Node_Id) is
838 Target : constant Node_Id := Name (N);
839 Cond : constant Node_Id := Condition (N);
840 Scope_Id : Entity_Id;
846 Check_Unreachable_Code (N);
849 if Present (Target) then
851 U_Name := Entity (Target);
853 if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then
854 Error_Msg_N ("invalid loop name in exit statement", N);
857 Set_Has_Exit (U_Name);
864 for J in reverse 0 .. Scope_Stack.Last loop
865 Scope_Id := Scope_Stack.Table (J).Entity;
866 Kind := Ekind (Scope_Id);
869 and then (No (Target) or else Scope_Id = U_Name) then
870 Set_Has_Exit (Scope_Id);
873 elsif Kind = E_Block or else Kind = E_Loop then
878 ("cannot exit from program unit or accept statement", N);
883 -- Verify that if present the condition is a Boolean expression
885 if Present (Cond) then
886 Analyze_And_Resolve (Cond, Any_Boolean);
887 Check_Unset_Reference (Cond);
889 end Analyze_Exit_Statement;
891 ----------------------------
892 -- Analyze_Goto_Statement --
893 ----------------------------
895 procedure Analyze_Goto_Statement (N : Node_Id) is
896 Label : constant Node_Id := Name (N);
897 Scope_Id : Entity_Id;
898 Label_Scope : Entity_Id;
901 Check_Unreachable_Code (N);
905 if Entity (Label) = Any_Id then
908 elsif Ekind (Entity (Label)) /= E_Label then
909 Error_Msg_N ("target of goto statement must be a label", Label);
912 elsif not Reachable (Entity (Label)) then
913 Error_Msg_N ("target of goto statement is not reachable", Label);
917 Label_Scope := Enclosing_Scope (Entity (Label));
919 for J in reverse 0 .. Scope_Stack.Last loop
920 Scope_Id := Scope_Stack.Table (J).Entity;
922 if Label_Scope = Scope_Id
923 or else (Ekind (Scope_Id) /= E_Block
924 and then Ekind (Scope_Id) /= E_Loop)
926 if Scope_Id /= Label_Scope then
928 ("cannot exit from program unit or accept statement", N);
936 end Analyze_Goto_Statement;
938 --------------------------
939 -- Analyze_If_Statement --
940 --------------------------
942 -- A special complication arises in the analysis of if statements.
944 -- The expander has circuitry to completely delete code that it
945 -- can tell will not be executed (as a result of compile time known
946 -- conditions). In the analyzer, we ensure that code that will be
947 -- deleted in this manner is analyzed but not expanded. This is
948 -- obviously more efficient, but more significantly, difficulties
949 -- arise if code is expanded and then eliminated (e.g. exception
950 -- table entries disappear). Similarly, itypes generated in deleted
951 -- code must be frozen from start, because the nodes on which they
952 -- depend will not be available at the freeze point.
954 procedure Analyze_If_Statement (N : Node_Id) is
957 Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
958 -- Recursively save value of this global, will be restored on exit
960 Save_In_Deleted_Code : Boolean;
962 Del : Boolean := False;
963 -- This flag gets set True if a True condition has been found,
964 -- which means that remaining ELSE/ELSIF parts are deleted.
966 procedure Analyze_Cond_Then (Cnode : Node_Id);
967 -- This is applied to either the N_If_Statement node itself or
968 -- to an N_Elsif_Part node. It deals with analyzing the condition
969 -- and the THEN statements associated with it.
971 -----------------------
972 -- Analyze_Cond_Then --
973 -----------------------
975 procedure Analyze_Cond_Then (Cnode : Node_Id) is
976 Cond : constant Node_Id := Condition (Cnode);
977 Tstm : constant List_Id := Then_Statements (Cnode);
980 Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
981 Analyze_And_Resolve (Cond, Any_Boolean);
982 Check_Unset_Reference (Cond);
983 Check_Possible_Current_Value_Condition (Cnode);
985 -- If already deleting, then just analyze then statements
988 Analyze_Statements (Tstm);
990 -- Compile time known value, not deleting yet
992 elsif Compile_Time_Known_Value (Cond) then
993 Save_In_Deleted_Code := In_Deleted_Code;
995 -- If condition is True, then analyze the THEN statements
996 -- and set no expansion for ELSE and ELSIF parts.
998 if Is_True (Expr_Value (Cond)) then
999 Analyze_Statements (Tstm);
1001 Expander_Mode_Save_And_Set (False);
1002 In_Deleted_Code := True;
1004 -- If condition is False, analyze THEN with expansion off
1006 else -- Is_False (Expr_Value (Cond))
1007 Expander_Mode_Save_And_Set (False);
1008 In_Deleted_Code := True;
1009 Analyze_Statements (Tstm);
1010 Expander_Mode_Restore;
1011 In_Deleted_Code := Save_In_Deleted_Code;
1014 -- Not known at compile time, not deleting, normal analysis
1017 Analyze_Statements (Tstm);
1019 end Analyze_Cond_Then;
1021 -- Start of Analyze_If_Statement
1024 -- Initialize exit count for else statements. If there is no else
1025 -- part, this count will stay non-zero reflecting the fact that the
1026 -- uncovered else case is an unblocked exit.
1028 Unblocked_Exit_Count := 1;
1029 Analyze_Cond_Then (N);
1031 -- Now to analyze the elsif parts if any are present
1033 if Present (Elsif_Parts (N)) then
1034 E := First (Elsif_Parts (N));
1035 while Present (E) loop
1036 Analyze_Cond_Then (E);
1041 if Present (Else_Statements (N)) then
1042 Analyze_Statements (Else_Statements (N));
1045 -- If all our exits were blocked by unconditional transfers of control,
1046 -- then the entire IF statement acts as an unconditional transfer of
1047 -- control, so treat it like one, and check unreachable code.
1049 if Unblocked_Exit_Count = 0 then
1050 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1051 Check_Unreachable_Code (N);
1053 Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
1057 Expander_Mode_Restore;
1058 In_Deleted_Code := Save_In_Deleted_Code;
1061 if not Expander_Active
1062 and then Compile_Time_Known_Value (Condition (N))
1063 and then Serious_Errors_Detected = 0
1065 if Is_True (Expr_Value (Condition (N))) then
1066 Remove_Warning_Messages (Else_Statements (N));
1068 if Present (Elsif_Parts (N)) then
1069 E := First (Elsif_Parts (N));
1071 while Present (E) loop
1072 Remove_Warning_Messages (Then_Statements (E));
1078 Remove_Warning_Messages (Then_Statements (N));
1081 end Analyze_If_Statement;
1083 ----------------------------------------
1084 -- Analyze_Implicit_Label_Declaration --
1085 ----------------------------------------
1087 -- An implicit label declaration is generated in the innermost
1088 -- enclosing declarative part. This is done for labels as well as
1089 -- block and loop names.
1091 -- Note: any changes in this routine may need to be reflected in
1092 -- Analyze_Label_Entity.
1094 procedure Analyze_Implicit_Label_Declaration (N : Node_Id) is
1095 Id : constant Node_Id := Defining_Identifier (N);
1098 Set_Ekind (Id, E_Label);
1099 Set_Etype (Id, Standard_Void_Type);
1100 Set_Enclosing_Scope (Id, Current_Scope);
1101 end Analyze_Implicit_Label_Declaration;
1103 ------------------------------
1104 -- Analyze_Iteration_Scheme --
1105 ------------------------------
1107 procedure Analyze_Iteration_Scheme (N : Node_Id) is
1109 procedure Process_Bounds (R : Node_Id);
1110 -- If the iteration is given by a range, create temporaries and
1111 -- assignment statements block to capture the bounds and perform
1112 -- required finalization actions in case a bound includes a function
1113 -- call that uses the temporary stack.
1115 procedure Check_Controlled_Array_Attribute (DS : Node_Id);
1116 -- If the bounds are given by a 'Range reference on a function call
1117 -- that returns a controlled array, introduce an explicit declaration
1118 -- to capture the bounds, so that the function result can be finalized
1119 -- in timely fashion.
1121 --------------------
1122 -- Process_Bounds --
1123 --------------------
1125 procedure Process_Bounds (R : Node_Id) is
1126 Loc : constant Source_Ptr := Sloc (N);
1127 Lo : constant Node_Id := Low_Bound (R);
1128 Hi : constant Node_Id := High_Bound (R);
1129 New_Lo_Bound : Node_Id := Empty;
1130 New_Hi_Bound : Node_Id := Empty;
1131 Typ : constant Entity_Id := Etype (R);
1133 function One_Bound (Bound : Node_Id) return Node_Id;
1134 -- Create one declaration followed by one assignment statement
1135 -- to capture the value of bound. We create a separate assignment
1136 -- in order to force the creation of a block in case the bound
1137 -- contains a call that uses the secondary stack.
1143 function One_Bound (Bound : Node_Id) return Node_Id is
1149 -- If the bound is a constant or an object, no need for a
1150 -- separate declaration. If the bound is the result of previous
1151 -- expansion it is already analyzed and should not be modified.
1153 if Nkind (Bound) = N_Integer_Literal
1154 or else Is_Entity_Name (Bound)
1155 or else Analyzed (Bound)
1157 Resolve (Bound, Typ);
1162 Make_Defining_Identifier (Loc,
1163 Chars => New_Internal_Name ('S'));
1166 Make_Object_Declaration (Loc,
1167 Defining_Identifier => Id,
1168 Object_Definition => New_Occurrence_Of (Typ, Loc));
1170 Insert_Before (Parent (N), Decl);
1174 Make_Assignment_Statement (Loc,
1175 Name => New_Occurrence_Of (Id, Loc),
1176 Expression => Relocate_Node (Bound));
1178 Save_Interps (Bound, Expression (Assign));
1179 Insert_Before (Parent (N), Assign);
1182 Rewrite (Bound, New_Occurrence_Of (Id, Loc));
1184 if Nkind (Assign) = N_Assignment_Statement then
1185 return Expression (Assign);
1191 -- Start of processing for Process_Bounds
1194 New_Lo_Bound := One_Bound (Lo);
1195 New_Hi_Bound := One_Bound (Hi);
1197 -- Propagate staticness to loop range itself, in case the
1198 -- corresponding subtype is static.
1200 if New_Lo_Bound /= Lo
1201 and then Is_Static_Expression (New_Lo_Bound)
1203 Rewrite (Low_Bound (R), New_Copy (New_Lo_Bound));
1206 if New_Hi_Bound /= Hi
1207 and then Is_Static_Expression (New_Hi_Bound)
1209 Rewrite (High_Bound (R), New_Copy (New_Hi_Bound));
1213 --------------------------------------
1214 -- Check_Controlled_Array_Attribute --
1215 --------------------------------------
1217 procedure Check_Controlled_Array_Attribute (DS : Node_Id) is
1219 if Nkind (DS) = N_Attribute_Reference
1220 and then Is_Entity_Name (Prefix (DS))
1221 and then Ekind (Entity (Prefix (DS))) = E_Function
1222 and then Is_Array_Type (Etype (Entity (Prefix (DS))))
1225 Component_Type (Etype (Entity (Prefix (DS)))))
1226 and then Expander_Active
1229 Loc : constant Source_Ptr := Sloc (N);
1230 Arr : constant Entity_Id :=
1231 Etype (Entity (Prefix (DS)));
1232 Indx : constant Entity_Id :=
1233 Base_Type (Etype (First_Index (Arr)));
1234 Subt : constant Entity_Id :=
1235 Make_Defining_Identifier
1236 (Loc, New_Internal_Name ('S'));
1241 Make_Subtype_Declaration (Loc,
1242 Defining_Identifier => Subt,
1243 Subtype_Indication =>
1244 Make_Subtype_Indication (Loc,
1245 Subtype_Mark => New_Reference_To (Indx, Loc),
1247 Make_Range_Constraint (Loc,
1248 Relocate_Node (DS))));
1249 Insert_Before (Parent (N), Decl);
1253 Make_Attribute_Reference (Loc,
1254 Prefix => New_Reference_To (Subt, Loc),
1255 Attribute_Name => Attribute_Name (DS)));
1259 end Check_Controlled_Array_Attribute;
1261 -- Start of processing for Analyze_Iteration_Scheme
1264 -- For an infinite loop, there is no iteration scheme
1271 Cond : constant Node_Id := Condition (N);
1274 -- For WHILE loop, verify that the condition is a Boolean
1275 -- expression and resolve and check it.
1277 if Present (Cond) then
1278 Analyze_And_Resolve (Cond, Any_Boolean);
1279 Check_Unset_Reference (Cond);
1281 -- Else we have a FOR loop
1285 LP : constant Node_Id := Loop_Parameter_Specification (N);
1286 Id : constant Entity_Id := Defining_Identifier (LP);
1287 DS : constant Node_Id := Discrete_Subtype_Definition (LP);
1292 -- We always consider the loop variable to be referenced,
1293 -- since the loop may be used just for counting purposes.
1295 Generate_Reference (Id, N, ' ');
1297 -- Check for case of loop variable hiding a local
1298 -- variable (used later on to give a nice warning
1299 -- if the hidden variable is never assigned).
1302 H : constant Entity_Id := Homonym (Id);
1305 and then Enclosing_Dynamic_Scope (H) =
1306 Enclosing_Dynamic_Scope (Id)
1307 and then Ekind (H) = E_Variable
1308 and then Is_Discrete_Type (Etype (H))
1310 Set_Hiding_Loop_Variable (H, Id);
1314 -- Now analyze the subtype definition. If it is
1315 -- a range, create temporaries for bounds.
1317 if Nkind (DS) = N_Range
1318 and then Expander_Active
1320 Pre_Analyze_And_Resolve (DS);
1321 Process_Bounds (DS);
1330 -- The subtype indication may denote the completion
1331 -- of an incomplete type declaration.
1333 if Is_Entity_Name (DS)
1334 and then Present (Entity (DS))
1335 and then Is_Type (Entity (DS))
1336 and then Ekind (Entity (DS)) = E_Incomplete_Type
1338 Set_Entity (DS, Get_Full_View (Entity (DS)));
1339 Set_Etype (DS, Entity (DS));
1342 if not Is_Discrete_Type (Etype (DS)) then
1343 Wrong_Type (DS, Any_Discrete);
1344 Set_Etype (DS, Any_Type);
1347 Check_Controlled_Array_Attribute (DS);
1349 Make_Index (DS, LP);
1351 Set_Ekind (Id, E_Loop_Parameter);
1352 Set_Etype (Id, Etype (DS));
1353 Set_Is_Known_Valid (Id, True);
1355 -- The loop is not a declarative part, so the only entity
1356 -- declared "within" must be frozen explicitly.
1359 Flist : constant List_Id := Freeze_Entity (Id, Sloc (N));
1361 if Is_Non_Empty_List (Flist) then
1362 Insert_Actions (N, Flist);
1366 -- Check for null or possibly null range and issue warning.
1367 -- We suppress such messages in generic templates and
1368 -- instances, because in practice they tend to be dubious
1371 if Nkind (DS) = N_Range
1372 and then Comes_From_Source (N)
1375 L : constant Node_Id := Low_Bound (DS);
1376 H : constant Node_Id := High_Bound (DS);
1386 Determine_Range (L, LOK, Llo, Lhi);
1387 Determine_Range (H, HOK, Hlo, Hhi);
1389 -- If range of loop is null, issue warning
1391 if (LOK and HOK) and then Llo > Hhi then
1393 -- Suppress the warning if inside a generic
1394 -- template or instance, since in practice
1395 -- they tend to be dubious in these cases since
1396 -- they can result from intended parametrization.
1398 if not Inside_A_Generic
1399 and then not In_Instance
1402 ("?loop range is null, loop will not execute",
1406 -- Since we know the range of the loop is null,
1407 -- set the appropriate flag to suppress any
1408 -- warnings that would otherwise be issued in
1409 -- the body of the loop that will not execute.
1410 -- We do this even in the generic case, since
1411 -- if it is dubious to warn on the null loop
1412 -- itself, it is certainly dubious to warn for
1413 -- conditions that occur inside it!
1415 Set_Is_Null_Loop (Parent (N));
1417 -- The other case for a warning is a reverse loop
1418 -- where the upper bound is the integer literal
1419 -- zero or one, and the lower bound can be positive.
1421 -- For example, we have
1423 -- for J in reverse N .. 1 loop
1425 -- In practice, this is very likely to be a case
1426 -- of reversing the bounds incorrectly in the range.
1428 elsif Reverse_Present (LP)
1429 and then Nkind (H) = N_Integer_Literal
1430 and then (Intval (H) = Uint_0
1432 Intval (H) = Uint_1)
1435 Error_Msg_N ("?loop range may be null", DS);
1443 end Analyze_Iteration_Scheme;
1449 -- Note: the semantic work required for analyzing labels (setting them as
1450 -- reachable) was done in a prepass through the statements in the block,
1451 -- so that forward gotos would be properly handled. See Analyze_Statements
1452 -- for further details. The only processing required here is to deal with
1453 -- optimizations that depend on an assumption of sequential control flow,
1454 -- since of course the occurrence of a label breaks this assumption.
1456 procedure Analyze_Label (N : Node_Id) is
1457 pragma Warnings (Off, N);
1459 Kill_Current_Values;
1462 --------------------------
1463 -- Analyze_Label_Entity --
1464 --------------------------
1466 procedure Analyze_Label_Entity (E : Entity_Id) is
1468 Set_Ekind (E, E_Label);
1469 Set_Etype (E, Standard_Void_Type);
1470 Set_Enclosing_Scope (E, Current_Scope);
1471 Set_Reachable (E, True);
1472 end Analyze_Label_Entity;
1474 ----------------------------
1475 -- Analyze_Loop_Statement --
1476 ----------------------------
1478 procedure Analyze_Loop_Statement (N : Node_Id) is
1479 Id : constant Node_Id := Identifier (N);
1483 if Present (Id) then
1485 -- Make name visible, e.g. for use in exit statements. Loop
1486 -- labels are always considered to be referenced.
1490 Generate_Reference (Ent, N, ' ');
1491 Generate_Definition (Ent);
1493 -- If we found a label, mark its type. If not, ignore it, since it
1494 -- means we have a conflicting declaration, which would already have
1495 -- been diagnosed at declaration time. Set Label_Construct of the
1496 -- implicit label declaration, which is not created by the parser
1497 -- for generic units.
1499 if Ekind (Ent) = E_Label then
1500 Set_Ekind (Ent, E_Loop);
1502 if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
1503 Set_Label_Construct (Parent (Ent), N);
1507 -- Case of no identifier present
1510 Ent := New_Internal_Entity (E_Loop, Current_Scope, Sloc (N), 'L');
1511 Set_Etype (Ent, Standard_Void_Type);
1512 Set_Parent (Ent, N);
1515 -- Kill current values on entry to loop, since statements in body
1516 -- of loop may have been executed before the loop is entered.
1517 -- Similarly we kill values after the loop, since we do not know
1518 -- that the body of the loop was executed.
1520 Kill_Current_Values;
1522 Analyze_Iteration_Scheme (Iteration_Scheme (N));
1523 Analyze_Statements (Statements (N));
1524 Process_End_Label (N, 'e', Ent);
1526 Kill_Current_Values;
1527 end Analyze_Loop_Statement;
1529 ----------------------------
1530 -- Analyze_Null_Statement --
1531 ----------------------------
1533 -- Note: the semantics of the null statement is implemented by a single
1534 -- null statement, too bad everything isn't as simple as this!
1536 procedure Analyze_Null_Statement (N : Node_Id) is
1537 pragma Warnings (Off, N);
1540 end Analyze_Null_Statement;
1542 ------------------------
1543 -- Analyze_Statements --
1544 ------------------------
1546 procedure Analyze_Statements (L : List_Id) is
1551 -- The labels declared in the statement list are reachable from
1552 -- statements in the list. We do this as a prepass so that any
1553 -- goto statement will be properly flagged if its target is not
1554 -- reachable. This is not required, but is nice behavior!
1557 while Present (S) loop
1558 if Nkind (S) = N_Label then
1559 Analyze (Identifier (S));
1560 Lab := Entity (Identifier (S));
1562 -- If we found a label mark it as reachable.
1564 if Ekind (Lab) = E_Label then
1565 Generate_Definition (Lab);
1566 Set_Reachable (Lab);
1568 if Nkind (Parent (Lab)) = N_Implicit_Label_Declaration then
1569 Set_Label_Construct (Parent (Lab), S);
1572 -- If we failed to find a label, it means the implicit declaration
1573 -- of the label was hidden. A for-loop parameter can do this to
1574 -- a label with the same name inside the loop, since the implicit
1575 -- label declaration is in the innermost enclosing body or block
1579 Error_Msg_Sloc := Sloc (Lab);
1581 ("implicit label declaration for & is hidden#",
1589 -- Perform semantic analysis on all statements
1591 Conditional_Statements_Begin;
1594 while Present (S) loop
1599 Conditional_Statements_End;
1601 -- Make labels unreachable. Visibility is not sufficient, because
1602 -- labels in one if-branch for example are not reachable from the
1603 -- other branch, even though their declarations are in the enclosing
1604 -- declarative part.
1607 while Present (S) loop
1608 if Nkind (S) = N_Label then
1609 Set_Reachable (Entity (Identifier (S)), False);
1614 end Analyze_Statements;
1616 --------------------------------------------
1617 -- Check_Possible_Current_Value_Condition --
1618 --------------------------------------------
1620 procedure Check_Possible_Current_Value_Condition (Cnode : Node_Id) is
1624 -- Loop to deal with (ignore for now) any NOT operators present
1626 Cond := Condition (Cnode);
1627 while Nkind (Cond) = N_Op_Not loop
1628 Cond := Right_Opnd (Cond);
1631 -- Check possible relational operator
1633 if Nkind (Cond) = N_Op_Eq
1635 Nkind (Cond) = N_Op_Ne
1637 Nkind (Cond) = N_Op_Ge
1639 Nkind (Cond) = N_Op_Le
1641 Nkind (Cond) = N_Op_Gt
1643 Nkind (Cond) = N_Op_Lt
1645 if Compile_Time_Known_Value (Right_Opnd (Cond))
1646 and then Nkind (Left_Opnd (Cond)) = N_Identifier
1649 Ent : constant Entity_Id := Entity (Left_Opnd (Cond));
1652 if Ekind (Ent) = E_Variable
1654 Ekind (Ent) = E_Constant
1658 Ekind (Ent) = E_Loop_Parameter
1660 -- Here we have a case where the Current_Value field
1661 -- may need to be set. We set it if it is not already
1662 -- set to a compile time expression value.
1664 -- Note that this represents a decision that one
1665 -- condition blots out another previous one. That's
1666 -- certainly right if they occur at the same level.
1667 -- If the second one is nested, then the decision is
1668 -- neither right nor wrong (it would be equally OK
1669 -- to leave the outer one in place, or take the new
1670 -- inner one. Really we should record both, but our
1671 -- data structures are not that elaborate.
1673 if Nkind (Current_Value (Ent)) not in N_Subexpr then
1674 Set_Current_Value (Ent, Cnode);
1680 end Check_Possible_Current_Value_Condition;
1682 ----------------------------
1683 -- Check_Unreachable_Code --
1684 ----------------------------
1686 procedure Check_Unreachable_Code (N : Node_Id) is
1687 Error_Loc : Source_Ptr;
1691 if Is_List_Member (N)
1692 and then Comes_From_Source (N)
1698 Nxt := Original_Node (Next (N));
1700 -- If a label follows us, then we never have dead code, since
1701 -- someone could branch to the label, so we just ignore it.
1703 if Nkind (Nxt) = N_Label then
1706 -- Otherwise see if we have a real statement following us
1709 and then Comes_From_Source (Nxt)
1710 and then Is_Statement (Nxt)
1712 -- Special very annoying exception. If we have a return that
1713 -- follows a raise, then we allow it without a warning, since
1714 -- the Ada RM annoyingly requires a useless return here!
1716 if Nkind (Original_Node (N)) /= N_Raise_Statement
1717 or else Nkind (Nxt) /= N_Return_Statement
1719 -- The rather strange shenanigans with the warning message
1720 -- here reflects the fact that Kill_Dead_Code is very good
1721 -- at removing warnings in deleted code, and this is one
1722 -- warning we would prefer NOT to have removed :-)
1724 Error_Loc := Sloc (Nxt);
1726 -- If we have unreachable code, analyze and remove the
1727 -- unreachable code, since it is useless and we don't
1728 -- want to generate junk warnings.
1730 -- We skip this step if we are not in code generation mode.
1731 -- This is the one case where we remove dead code in the
1732 -- semantics as opposed to the expander, and we do not want
1733 -- to remove code if we are not in code generation mode,
1734 -- since this messes up the ASIS trees.
1736 -- Note that one might react by moving the whole circuit to
1737 -- exp_ch5, but then we lose the warning in -gnatc mode.
1739 if Operating_Mode = Generate_Code then
1743 -- Quit deleting when we have nothing more to delete
1744 -- or if we hit a label (since someone could transfer
1745 -- control to a label, so we should not delete it).
1747 exit when No (Nxt) or else Nkind (Nxt) = N_Label;
1749 -- Statement/declaration is to be deleted
1753 Kill_Dead_Code (Nxt);
1757 -- Now issue the warning
1759 Error_Msg ("?unreachable code", Error_Loc);
1762 -- If the unconditional transfer of control instruction is
1763 -- the last statement of a sequence, then see if our parent
1764 -- is one of the constructs for which we count unblocked exits,
1765 -- and if so, adjust the count.
1770 -- Statements in THEN part or ELSE part of IF statement
1772 if Nkind (P) = N_If_Statement then
1775 -- Statements in ELSIF part of an IF statement
1777 elsif Nkind (P) = N_Elsif_Part then
1779 pragma Assert (Nkind (P) = N_If_Statement);
1781 -- Statements in CASE statement alternative
1783 elsif Nkind (P) = N_Case_Statement_Alternative then
1785 pragma Assert (Nkind (P) = N_Case_Statement);
1787 -- Statements in body of block
1789 elsif Nkind (P) = N_Handled_Sequence_Of_Statements
1790 and then Nkind (Parent (P)) = N_Block_Statement
1794 -- Statements in exception handler in a block
1796 elsif Nkind (P) = N_Exception_Handler
1797 and then Nkind (Parent (P)) = N_Handled_Sequence_Of_Statements
1798 and then Nkind (Parent (Parent (P))) = N_Block_Statement
1802 -- None of these cases, so return
1808 -- This was one of the cases we are looking for (i.e. the
1809 -- parent construct was IF, CASE or block) so decrement count.
1811 Unblocked_Exit_Count := Unblocked_Exit_Count - 1;
1815 end Check_Unreachable_Code;