-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2005 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2006, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
with Atree; use Atree;
with Checks; use Checks;
+with Debug; use Debug;
with Einfo; use Einfo;
with Errout; use Errout;
with Expander; use Expander;
with Exp_Util; use Exp_Util;
with Freeze; use Freeze;
+with Lib; use Lib;
with Lib.Xref; use Lib.Xref;
with Nlists; use Nlists;
with Nmake; use Nmake;
with Opt; use Opt;
+with Rtsfind; use Rtsfind;
with Sem; use Sem;
with Sem_Case; use Sem_Case;
with Sem_Ch3; use Sem_Ch3;
with Sem_Ch8; use Sem_Ch8;
with Sem_Disp; use Sem_Disp;
+with Sem_Elab; use Sem_Elab;
with Sem_Eval; use Sem_Eval;
with Sem_Res; use Sem_Res;
with Sem_Type; use Sem_Type;
with Sem_Util; use Sem_Util;
with Sem_Warn; use Sem_Warn;
+with Snames; use Snames;
with Stand; use Stand;
with Sinfo; use Sinfo;
with Targparm; use Targparm;
Unblocked_Exit_Count : Nat := 0;
-- This variable is used when processing if statements, case statements,
-- and block statements. It counts the number of exit points that are
- -- not blocked by unconditional transfer instructions (for IF and CASE,
- -- these are the branches of the conditional, for a block, they are the
+ -- not blocked by unconditional transfer instructions: for IF and CASE,
+ -- these are the branches of the conditional; for a block, they are the
-- statement sequence of the block, and the statement sequences of any
-- exception handlers that are part of the block. When processing is
-- complete, if this count is zero, it means that control cannot fall
procedure Analyze_Iteration_Scheme (N : Node_Id);
- procedure Check_Possible_Current_Value_Condition (Cnode : Node_Id);
- -- Cnode is N_If_Statement, N_Elsif_Part, or N_Iteration_Scheme
- -- (the latter when a WHILE condition is present). This call checks
- -- if Condition (Cnode) is of the form ([NOT] var op val), where var
- -- is a simple object, val is known at compile time, and op is one
- -- of the six relational operators. If this is the case, and the
- -- Current_Value field of "var" is not set, then it is set to Cnode.
- -- See Exp_Util.Set_Current_Value_Condition for further details.
-
------------------------
-- Analyze_Assignment --
------------------------
T1 : Entity_Id;
T2 : Entity_Id;
Decl : Node_Id;
- Ent : Entity_Id;
procedure Diagnose_Non_Variable_Lhs (N : Node_Id);
-- N is the node for the left hand side of an assignment, and it
-- is not a variable. This routine issues an appropriate diagnostic.
+ procedure Kill_Lhs;
+ -- This is called to kill current value settings of a simple variable
+ -- on the left hand side. We call it if we find any error in analyzing
+ -- the assignment, and at the end of processing before setting any new
+ -- current values in place.
+
procedure Set_Assignment_Type
(Opnd : Node_Id;
Opnd_Type : in out Entity_Id);
end if;
end Diagnose_Non_Variable_Lhs;
+ --------------
+ -- Kill_LHS --
+ --------------
+
+ procedure Kill_Lhs is
+ begin
+ if Is_Entity_Name (Lhs) then
+ declare
+ Ent : constant Entity_Id := Entity (Lhs);
+ begin
+ if Present (Ent) then
+ Kill_Current_Values (Ent);
+ end if;
+ end;
+ end if;
+ end Kill_Lhs;
+
-------------------------
-- Set_Assignment_Type --
-------------------------
begin
Analyze (Rhs);
Analyze (Lhs);
+
+ -- Start type analysis for assignment
+
T1 := Etype (Lhs);
-- In the most general case, both Lhs and Rhs can be overloaded, and we
if T1 = Any_Type then
Error_Msg_N
("no valid types for left-hand side for assignment", Lhs);
+ Kill_Lhs;
return;
end if;
end if;
Resolve (Lhs, T1);
if not Is_Variable (Lhs) then
+
+ -- Ada 2005 (AI-327): Check assignment to the attribute Priority of
+ -- a protected object.
+
+ declare
+ Ent : Entity_Id;
+ S : Entity_Id;
+
+ begin
+ if Ada_Version >= Ada_05 then
+
+ -- Handle chains of renamings
+
+ Ent := Lhs;
+ while Nkind (Ent) in N_Has_Entity
+ and then Present (Entity (Ent))
+ and then Present (Renamed_Object (Entity (Ent)))
+ loop
+ Ent := Renamed_Object (Entity (Ent));
+ end loop;
+
+ if (Nkind (Ent) = N_Attribute_Reference
+ and then Attribute_Name (Ent) = Name_Priority)
+
+ -- Renamings of the attribute Priority applied to protected
+ -- objects have been previously expanded into calls to the
+ -- Get_Ceiling run-time subprogram.
+
+ or else
+ (Nkind (Ent) = N_Function_Call
+ and then (Entity (Name (Ent)) = RTE (RE_Get_Ceiling)
+ or else
+ Entity (Name (Ent)) = RTE (RO_PE_Get_Ceiling)))
+ then
+ -- The enclosing subprogram cannot be a protected function
+
+ S := Current_Scope;
+ while not (Is_Subprogram (S)
+ and then Convention (S) = Convention_Protected)
+ and then S /= Standard_Standard
+ loop
+ S := Scope (S);
+ end loop;
+
+ if Ekind (S) = E_Function
+ and then Convention (S) = Convention_Protected
+ then
+ Error_Msg_N
+ ("protected function cannot modify protected object",
+ Lhs);
+ end if;
+
+ -- Changes of the ceiling priority of the protected object
+ -- are only effective if the Ceiling_Locking policy is in
+ -- effect (AARM D.5.2 (5/2)).
+
+ if Locking_Policy /= 'C' then
+ Error_Msg_N ("assignment to the attribute PRIORITY has " &
+ "no effect?", Lhs);
+ Error_Msg_N ("\since no Locking_Policy has been " &
+ "specified", Lhs);
+ end if;
+
+ return;
+ end if;
+ end if;
+ end;
+
Diagnose_Non_Variable_Lhs (Lhs);
return;
and then Ekind (T1) = E_Incomplete_Type
then
Error_Msg_N ("invalid use of incomplete type", Lhs);
+ Kill_Lhs;
return;
end if;
-- Remaining steps are skipped if Rhs was syntactically in error
if Rhs = Error then
+ Kill_Lhs;
return;
end if;
T2 := Etype (Rhs);
- if Covers (T1, T2) then
- null;
- else
+ if not Covers (T1, T2) then
Wrong_Type (Rhs, Etype (Lhs));
+ Kill_Lhs;
return;
end if;
end if;
if T1 = Any_Type or else T2 = Any_Type then
+ Kill_Lhs;
return;
end if;
Error_Msg_N ("dynamically tagged expression required!", Rhs);
end if;
- -- Tag propagation is done only in semantics mode only. If expansion
- -- is on, the rhs tag indeterminate function call has been expanded
- -- and tag propagation would have happened too late, so the
- -- propagation take place in expand_call instead.
+ -- Propagate the tag from a class-wide target to the rhs when the rhs
+ -- is a tag-indeterminate call.
- if not Expander_Active
- and then Is_Class_Wide_Type (T1)
- and then Is_Tag_Indeterminate (Rhs)
- then
- Propagate_Tag (Lhs, Rhs);
+ if Is_Tag_Indeterminate (Rhs) then
+ if Is_Class_Wide_Type (T1) then
+ Propagate_Tag (Lhs, Rhs);
+
+ elsif Nkind (Rhs) = N_Function_Call
+ and then Is_Entity_Name (Name (Rhs))
+ and then Is_Abstract_Subprogram (Entity (Name (Rhs)))
+ then
+ Error_Msg_N
+ ("call to abstract function must be dispatching", Name (Rhs));
+
+ elsif Nkind (Rhs) = N_Qualified_Expression
+ and then Nkind (Expression (Rhs)) = N_Function_Call
+ and then Is_Entity_Name (Name (Expression (Rhs)))
+ and then
+ Is_Abstract_Subprogram (Entity (Name (Expression (Rhs))))
+ then
+ Error_Msg_N
+ ("call to abstract function must be dispatching",
+ Name (Expression (Rhs)));
+ end if;
end if;
-- Ada 2005 (AI-230 and AI-385): When the lhs type is an anonymous
-- Ada 2005 (AI-231)
if Ada_Version >= Ada_05
- and then Nkind (Rhs) = N_Null
- and then Is_Access_Type (T1)
+ and then Can_Never_Be_Null (T1)
and then not Assignment_OK (Lhs)
- and then ((Is_Entity_Name (Lhs)
- and then Can_Never_Be_Null (Entity (Lhs)))
- or else Can_Never_Be_Null (Etype (Lhs)))
then
- Apply_Compile_Time_Constraint_Error
- (N => Lhs,
- Msg => "(Ada 2005) NULL not allowed in null-excluding objects?",
- Reason => CE_Null_Not_Allowed);
+ if Nkind (Rhs) = N_Null then
+ Apply_Compile_Time_Constraint_Error
+ (N => Rhs,
+ Msg => "(Ada 2005) NULL not allowed in null-excluding objects?",
+ Reason => CE_Null_Not_Allowed);
+ return;
+
+ elsif not Can_Never_Be_Null (T2) then
+ Rewrite (Rhs,
+ Convert_To (T1, Relocate_Node (Rhs)));
+ Analyze_And_Resolve (Rhs, T1);
+ end if;
end if;
if Is_Scalar_Type (T1) then
Apply_Scalar_Range_Check (Rhs, Etype (Lhs));
+ -- For array types, verify that lengths match. If the right hand side
+ -- if a function call that has been inlined, the assignment has been
+ -- rewritten as a block, and the constraint check will be applied to the
+ -- assignment within the block.
+
elsif Is_Array_Type (T1)
and then
(Nkind (Rhs) /= N_Type_Conversion
- or else Is_Constrained (Etype (Rhs)))
+ or else Is_Constrained (Etype (Rhs)))
+ and then
+ (Nkind (Rhs) /= N_Function_Call
+ or else Nkind (N) /= N_Block_Statement)
then
-- Assignment verifies that the length of the Lsh and Rhs are equal,
-- but of course the indices do not have to match. If the right-hand
-- ??? a real accessibility check is needed when ???
- -- Post warning for useless assignment
+ -- Post warning for redundant assignment or variable to itself
if Warn_On_Redundant_Constructs
Error_Msg_CRT ("composite assignment", N);
end if;
- -- One more step. Let's see if we have a simple assignment of a
- -- known at compile time value to a simple variable. If so, we
- -- can record the value as the current value providing that:
+ -- Check elaboration warning for left side if not in elab code
+
+ if not In_Subprogram_Or_Concurrent_Unit then
+ Check_Elab_Assign (Lhs);
+ end if;
+
+ -- Final step. If left side is an entity, then we may be able to
+ -- reset the current tracked values to new safe values. We only have
+ -- something to do if the left side is an entity name, and expansion
+ -- has not modified the node into something other than an assignment,
+ -- and of course we only capture values if it is safe to do so.
+
+ if Is_Entity_Name (Lhs)
+ and then Nkind (N) = N_Assignment_Statement
+ then
+ declare
+ Ent : constant Entity_Id := Entity (Lhs);
+
+ begin
+ if Safe_To_Capture_Value (N, Ent) then
+
+ -- If simple variable on left side, warn if this assignment
+ -- blots out another one (rendering it useless) and note
+ -- location of assignment in case no one references value.
+ -- We only do this for source assignments, otherwise we can
+ -- generate bogus warnings when an assignment is rewritten as
+ -- another assignment, and gets tied up with itself.
+
+ if Warn_On_Modified_Unread
+ and then Ekind (Ent) = E_Variable
+ and then Comes_From_Source (N)
+ and then In_Extended_Main_Source_Unit (Ent)
+ then
+ Warn_On_Useless_Assignment (Ent, Sloc (N));
+ Set_Last_Assignment (Ent, Lhs);
+ end if;
- -- We still have a simple assignment statement (no expansion
- -- activity has modified it in some peculiar manner)
+ -- If we are assigning an access type and the left side is an
+ -- entity, then make sure that the Is_Known_[Non_]Null flags
+ -- properly reflect the state of the entity after assignment.
- -- The type is a discrete type
+ if Is_Access_Type (T1) then
+ if Known_Non_Null (Rhs) then
+ Set_Is_Known_Non_Null (Ent, True);
- -- The assignment is to a named entity
+ elsif Known_Null (Rhs)
+ and then not Can_Never_Be_Null (Ent)
+ then
+ Set_Is_Known_Null (Ent, True);
- -- The value is known at compile time
+ else
+ Set_Is_Known_Null (Ent, False);
- if Nkind (N) /= N_Assignment_Statement
- or else not Is_Discrete_Type (T1)
- or else not Is_Entity_Name (Lhs)
- or else not Compile_Time_Known_Value (Rhs)
- then
- return;
- end if;
+ if not Can_Never_Be_Null (Ent) then
+ Set_Is_Known_Non_Null (Ent, False);
+ end if;
+ end if;
- Ent := Entity (Lhs);
+ -- For discrete types, we may be able to set the current value
+ -- if the value is known at compile time.
+
+ elsif Is_Discrete_Type (T1)
+ and then Compile_Time_Known_Value (Rhs)
+ then
+ Set_Current_Value (Ent, Rhs);
+ else
+ Set_Current_Value (Ent, Empty);
+ end if;
- -- Capture value if save to do so
+ -- If not safe to capture values, kill them
- if Safe_To_Capture_Value (N, Ent) then
- Set_Current_Value (Ent, Rhs);
+ else
+ Kill_Lhs;
+ end if;
+ end;
end if;
end Analyze_Assignment;
end if;
Check_References (Ent);
+ Warn_On_Useless_Assignments (Ent);
End_Scope;
if Unblocked_Exit_Count = 0 then
Set_Has_Exit (Scope_Id);
exit;
- elsif Kind = E_Block or else Kind = E_Loop then
+ elsif Kind = E_Block
+ or else Kind = E_Loop
+ or else Kind = E_Return_Statement
+ then
null;
else
Label : constant Node_Id := Name (N);
Scope_Id : Entity_Id;
Label_Scope : Entity_Id;
+ Label_Ent : Entity_Id;
begin
Check_Unreachable_Code (N);
Analyze (Label);
+ Label_Ent := Entity (Label);
+
+ -- Ignore previous error
- if Entity (Label) = Any_Id then
+ if Label_Ent = Any_Id then
return;
- elsif Ekind (Entity (Label)) /= E_Label then
+ -- We just have a label as the target of a goto
+
+ elsif Ekind (Label_Ent) /= E_Label then
Error_Msg_N ("target of goto statement must be a label", Label);
return;
- elsif not Reachable (Entity (Label)) then
+ -- Check that the target of the goto is reachable according to Ada
+ -- scoping rules. Note: the special gotos we generate for optimizing
+ -- local handling of exceptions would violate these rules, but we mark
+ -- such gotos as analyzed when built, so this code is never entered.
+
+ elsif not Reachable (Label_Ent) then
Error_Msg_N ("target of goto statement is not reachable", Label);
return;
end if;
- Label_Scope := Enclosing_Scope (Entity (Label));
+ -- Here if goto passes initial validity checks
+
+ Label_Scope := Enclosing_Scope (Label_Ent);
for J in reverse 0 .. Scope_Stack.Last loop
Scope_Id := Scope_Stack.Table (J).Entity;
if Label_Scope = Scope_Id
or else (Ekind (Scope_Id) /= E_Block
- and then Ekind (Scope_Id) /= E_Loop)
+ and then Ekind (Scope_Id) /= E_Loop
+ and then Ekind (Scope_Id) /= E_Return_Statement)
then
if Scope_Id /= Label_Scope then
Error_Msg_N
Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
- Check_Possible_Current_Value_Condition (Cnode);
+ Set_Current_Value_Condition (Cnode);
-- If already deleting, then just analyze then statements
New_Lo_Bound : Node_Id := Empty;
New_Hi_Bound : Node_Id := Empty;
Typ : Entity_Id;
+ Save_Analysis : Boolean;
function One_Bound
(Original_Bound : Node_Id;
-- Start of processing for Process_Bounds
begin
- -- Determine expected type of range by analyzing separate copy.
+ -- Determine expected type of range by analyzing separate copy
+ -- Do the analysis and resolution of the copy of the bounds with
+ -- expansion disabled, to prevent the generation of finalization
+ -- actions on each bound. This prevents memory leaks when the
+ -- bounds contain calls to functions returning controlled arrays.
Set_Parent (R_Copy, Parent (R));
- Pre_Analyze_And_Resolve (R_Copy);
+ Save_Analysis := Full_Analysis;
+ Full_Analysis := False;
+ Expander_Mode_Save_And_Set (False);
+
+ Analyze (R_Copy);
+
+ if Is_Overloaded (R_Copy) then
+
+ -- Apply preference rules for range of predefined integer types,
+ -- or diagnose true ambiguity.
+
+ declare
+ I : Interp_Index;
+ It : Interp;
+ Found : Entity_Id := Empty;
+
+ begin
+ Get_First_Interp (R_Copy, I, It);
+ while Present (It.Typ) loop
+ if Is_Discrete_Type (It.Typ) then
+ if No (Found) then
+ Found := It.Typ;
+ else
+ if Scope (Found) = Standard_Standard then
+ null;
+
+ elsif Scope (It.Typ) = Standard_Standard then
+ Found := It.Typ;
+
+ else
+ -- Both of them are user-defined
+
+ Error_Msg_N
+ ("ambiguous bounds in range of iteration",
+ R_Copy);
+ Error_Msg_N ("\possible interpretations:", R_Copy);
+ Error_Msg_NE ("\\} ", R_Copy, Found);
+ Error_Msg_NE ("\\} ", R_Copy, It.Typ);
+ exit;
+ end if;
+ end if;
+ end if;
+
+ Get_Next_Interp (I, It);
+ end loop;
+ end;
+ end if;
+
+ Resolve (R_Copy);
+ Expander_Mode_Restore;
+ Full_Analysis := Save_Analysis;
+
Typ := Etype (R_Copy);
-- If the type of the discrete range is Universal_Integer, then
-- the bound's type must be resolved to Integer, and any object
- -- used to hold the bound must also have type Integer.
+ -- used to hold the bound must also have type Integer, unless the
+ -- literal bounds are constant-folded expressions that carry a user-
+ -- defined type.
if Typ = Universal_Integer then
- Typ := Standard_Integer;
+ if Nkind (Lo) = N_Integer_Literal
+ and then Present (Etype (Lo))
+ and then Scope (Etype (Lo)) /= Standard_Standard
+ then
+ Typ := Etype (Lo);
+
+ elsif Nkind (Hi) = N_Integer_Literal
+ and then Present (Etype (Hi))
+ and then Scope (Etype (Hi)) /= Standard_Standard
+ then
+ Typ := Etype (Hi);
+
+ else
+ Typ := Standard_Integer;
+ end if;
end if;
Set_Etype (R, Typ);
if Present (Cond) then
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
+ Set_Current_Value_Condition (N);
+ return;
-- Else we have a FOR loop
-- of reversing the bounds incorrectly in the range.
elsif Reverse_Present (LP)
- and then Nkind (H) = N_Integer_Literal
+ and then Nkind (Original_Node (H)) =
+ N_Integer_Literal
and then (Intval (H) = Uint_0
or else
Intval (H) = Uint_1)
and then Lhi > Hhi
then
Error_Msg_N ("?loop range may be null", DS);
+ Error_Msg_N ("\?bounds may be wrong way round", DS);
end if;
end;
end if;
----------------------------
procedure Analyze_Loop_Statement (N : Node_Id) is
- Id : constant Node_Id := Identifier (N);
- Ent : Entity_Id;
+ Id : constant Node_Id := Identifier (N);
+ Iter : constant Node_Id := Iteration_Scheme (N);
+ Ent : Entity_Id;
begin
if Present (Id) then
Kill_Current_Values;
New_Scope (Ent);
- Analyze_Iteration_Scheme (Iteration_Scheme (N));
+ Analyze_Iteration_Scheme (Iter);
Analyze_Statements (Statements (N));
Process_End_Label (N, 'e', Ent);
End_Scope;
Kill_Current_Values;
+
+ -- Check for possible infinite loop which we can diagnose successfully.
+ -- The case we look for is a while loop which tests a local variable,
+ -- where there is no obvious direct or indirect update of the variable
+ -- within the body of the loop.
+
+ -- Note: we don't try to give a warning if condition actions are
+ -- present, since the loop structure can be very complex in this case.
+
+ if No (Iter)
+ or else No (Condition (Iter))
+ or else Present (Condition_Actions (Iter))
+ or else Debug_Flag_Dot_W
+ then
+ return;
+ end if;
+
+ -- Initial conditions met, see if condition is of right form
+
+ declare
+ Loc : Node_Id := Empty;
+ Var : Entity_Id := Empty;
+
+ function Has_Indirection (T : Entity_Id) return Boolean;
+ -- If the controlling variable is an access type, or is a record type
+ -- with access components, assume that it is changed indirectly and
+ -- suppress the warning. As a concession to low-level programming, in
+ -- particular within Declib, we also suppress warnings on a record
+ -- type that contains components of type Address or Short_Address.
+
+ procedure Find_Var (N : Node_Id);
+ -- Find whether the condition in a while-loop can be reduced to
+ -- a test on a single variable. Recurse if condition is negation.
+
+ ---------------------
+ -- Has_Indirection --
+ ---------------------
+
+ function Has_Indirection (T : Entity_Id) return Boolean is
+ Comp : Entity_Id;
+ Rec : Entity_Id;
+
+ begin
+ if Is_Access_Type (T) then
+ return True;
+
+ elsif Is_Private_Type (T)
+ and then Present (Full_View (T))
+ and then Is_Access_Type (Full_View (T))
+ then
+ return True;
+
+ elsif Is_Record_Type (T) then
+ Rec := T;
+
+ elsif Is_Private_Type (T)
+ and then Present (Full_View (T))
+ and then Is_Record_Type (Full_View (T))
+ then
+ Rec := Full_View (T);
+ else
+ return False;
+ end if;
+
+ Comp := First_Component (Rec);
+ while Present (Comp) loop
+ if Is_Access_Type (Etype (Comp))
+ or else Is_Descendent_Of_Address (Etype (Comp))
+ then
+ return True;
+ end if;
+
+ Next_Component (Comp);
+ end loop;
+
+ return False;
+ end Has_Indirection;
+
+ --------------
+ -- Find_Var --
+ --------------
+
+ procedure Find_Var (N : Node_Id) is
+ begin
+ -- Condition is a direct variable reference
+
+ if Is_Entity_Name (N)
+ and then not Is_Library_Level_Entity (Entity (N))
+ then
+ Loc := N;
+
+ -- Case of condition is a comparison with compile time known value
+
+ elsif Nkind (N) in N_Op_Compare then
+ if Is_Entity_Name (Left_Opnd (N))
+ and then Compile_Time_Known_Value (Right_Opnd (N))
+ then
+ Loc := Left_Opnd (N);
+
+ elsif Is_Entity_Name (Right_Opnd (N))
+ and then Compile_Time_Known_Value (Left_Opnd (N))
+ then
+ Loc := Right_Opnd (N);
+
+ else
+ return;
+ end if;
+
+ -- If condition is a negation, check whether the operand has the
+ -- proper form.
+
+ elsif Nkind (N) = N_Op_Not then
+ Find_Var (Right_Opnd (N));
+
+ -- Case of condition is function call with one parameter
+
+ elsif Nkind (N) = N_Function_Call then
+ declare
+ PA : constant List_Id := Parameter_Associations (N);
+ begin
+ if Present (PA)
+ and then List_Length (PA) = 1
+ and then Is_Entity_Name (First (PA))
+ then
+ Loc := First (PA);
+ else
+ return;
+ end if;
+ end;
+
+ else
+ return;
+ end if;
+ end Find_Var;
+
+ begin
+ Find_Var (Condition (Iter));
+
+ if Present (Loc) then
+ Var := Entity (Loc);
+ end if;
+
+ if Present (Var)
+ and then Ekind (Var) = E_Variable
+ and then not Is_Library_Level_Entity (Var)
+ and then Comes_From_Source (Var)
+ then
+ if Has_Indirection (Etype (Var)) then
+
+ -- Assume that the designated object is modified in some
+ -- other way, to avoid false positives.
+
+ return;
+
+ elsif Is_Volatile (Var) then
+
+ -- If the variable is marked as volatile, we assume that
+ -- the condition may be affected by other tasks.
+
+ return;
+
+ elsif Nkind (Original_Node (First (Statements (N))))
+ = N_Delay_Relative_Statement
+ or else Nkind (Original_Node (First (Statements (N))))
+ = N_Delay_Until_Statement
+ then
+
+ -- Assume that this is a multitasking program, and the
+ -- condition is affected by other threads.
+
+ return;
+
+ end if;
+
+ -- There no identifiable single variable in the condition
+
+ else
+ return;
+ end if;
+
+ -- Search for reference to variable in loop
+
+ Ref_Search : declare
+ function Test_Ref (N : Node_Id) return Traverse_Result;
+ -- Test for reference to variable in question. Returns Abandon
+ -- if matching reference found.
+
+ function Find_Ref is new Traverse_Func (Test_Ref);
+ -- Function to traverse body of procedure. Returns Abandon if
+ -- matching reference found.
+
+ --------------
+ -- Test_Ref --
+ --------------
+
+ function Test_Ref (N : Node_Id) return Traverse_Result is
+ begin
+ -- Waste of time to look at iteration scheme
+
+ if N = Iter then
+ return Skip;
+
+ -- Direct reference to variable in question
+
+ elsif Is_Entity_Name (N)
+ and then Present (Entity (N))
+ and then Entity (N) = Var
+ and then May_Be_Lvalue (N)
+ then
+ return Abandon;
+
+ -- Reference to variable renaming variable in question
+
+ elsif Is_Entity_Name (N)
+ and then Present (Entity (N))
+ and then Ekind (Entity (N)) = E_Variable
+ and then Present (Renamed_Object (Entity (N)))
+ and then Is_Entity_Name (Renamed_Object (Entity (N)))
+ and then Entity (Renamed_Object (Entity (N))) = Var
+ and then May_Be_Lvalue (N)
+ then
+ return Abandon;
+
+ -- Calls to subprograms are OK, unless the subprogram is
+ -- within the scope of the entity in question and could
+ -- therefore possibly modify it
+
+ elsif Nkind (N) = N_Procedure_Call_Statement
+ or else Nkind (N) = N_Function_Call
+ then
+ if not Is_Entity_Name (Name (N))
+ or else Scope_Within (Entity (Name (N)), Scope (Var))
+ then
+ return Abandon;
+ end if;
+ end if;
+
+ -- All OK, continue scan
+
+ return OK;
+ end Test_Ref;
+
+ -- Start of processing for Ref_Search
+
+ begin
+ if Find_Ref (N) = OK then
+ Error_Msg_NE
+ ("variable& is not modified in loop body?", Loc, Var);
+ Error_Msg_N
+ ("\possible infinite loop", Loc);
+ end if;
+ end Ref_Search;
+ end;
end Analyze_Loop_Statement;
----------------------------
end loop;
end Analyze_Statements;
- --------------------------------------------
- -- Check_Possible_Current_Value_Condition --
- --------------------------------------------
-
- procedure Check_Possible_Current_Value_Condition (Cnode : Node_Id) is
- Cond : Node_Id;
-
- begin
- -- Loop to deal with (ignore for now) any NOT operators present
-
- Cond := Condition (Cnode);
- while Nkind (Cond) = N_Op_Not loop
- Cond := Right_Opnd (Cond);
- end loop;
-
- -- Check possible relational operator
-
- if Nkind (Cond) = N_Op_Eq
- or else
- Nkind (Cond) = N_Op_Ne
- or else
- Nkind (Cond) = N_Op_Ge
- or else
- Nkind (Cond) = N_Op_Le
- or else
- Nkind (Cond) = N_Op_Gt
- or else
- Nkind (Cond) = N_Op_Lt
- then
- if Compile_Time_Known_Value (Right_Opnd (Cond))
- and then Nkind (Left_Opnd (Cond)) = N_Identifier
- then
- declare
- Ent : constant Entity_Id := Entity (Left_Opnd (Cond));
-
- begin
- if Ekind (Ent) = E_Variable
- or else
- Ekind (Ent) = E_Constant
- or else
- Is_Formal (Ent)
- or else
- Ekind (Ent) = E_Loop_Parameter
- then
- -- Here we have a case where the Current_Value field
- -- may need to be set. We set it if it is not already
- -- set to a compile time expression value.
-
- -- Note that this represents a decision that one
- -- condition blots out another previous one. That's
- -- certainly right if they occur at the same level.
- -- If the second one is nested, then the decision is
- -- neither right nor wrong (it would be equally OK
- -- to leave the outer one in place, or take the new
- -- inner one. Really we should record both, but our
- -- data structures are not that elaborate.
-
- if Nkind (Current_Value (Ent)) not in N_Subexpr then
- Set_Current_Value (Ent, Cnode);
- end if;
- end if;
- end;
- end if;
- end if;
- end Check_Possible_Current_Value_Condition;
-
----------------------------
-- Check_Unreachable_Code --
----------------------------
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