-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2004 Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2007, 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- --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, USA. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
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 Namet; use Namet;
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;
package body Sem_Ch5 is
Unblocked_Exit_Count : Nat := 0;
- -- This variable is used when processing if statements or case
- -- statements, it counts the number of branches of the conditional
- -- that are not blocked by unconditional transfer instructions. At
- -- the end of processing, if the count is zero, it means that control
- -- cannot fall through the conditional statement. This is used for
- -- the generation of warning messages. This variable is recursively
- -- saved on entry to processing an if or case, and restored on exit.
+ -- 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 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 through the IF,
+ -- CASE or block statement. This is used for the generation of warning
+ -- messages. This variable is recursively saved on entry to processing the
+ -- construct, and restored on exit.
-----------------------
-- Local Subprograms --
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);
procedure Diagnose_Non_Variable_Lhs (N : Node_Id) is
begin
-- Not worth posting another error if left hand side already
- -- flagged as being illegal in some respect
+ -- flagged as being illegal in some respect.
if Error_Posted (N) then
return;
elsif Nkind (N) = N_Indexed_Component then
Diagnose_Non_Variable_Lhs (Prefix (N));
- -- Another special case for assignment to discriminant.
+ -- Another special case for assignment to discriminant
elsif Nkind (N) = N_Selected_Component then
if Present (Entity (Selector_Name (N)))
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 --
-------------------------
-- Start of processing for Analyze_Assignment
begin
+ Mark_Static_Coextensions (Rhs);
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;
+ -- The resulting assignment type is T1, so now we will resolve the
+ -- left hand side of the assignment using this determined type.
+
Resolve (Lhs, T1);
+ -- Cases where Lhs is not a variable
+
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;
+ -- Error of assigning to limited type. We do however allow this in
+ -- certain cases where the front end generates the assignments.
+
elsif Is_Limited_Type (T1)
and then not Assignment_OK (Lhs)
and then not Assignment_OK (Original_Node (Lhs))
+ and then not Is_Value_Type (T1)
then
Error_Msg_N
("left hand of assignment must not be limited type", Lhs);
-- to avoid scoping issues in the back-end.
T1 := Etype (Lhs);
- Set_Assignment_Type (Lhs, T1);
+ -- Ada 2005 (AI-50217, AI-326): Check wrong dereference of incomplete
+ -- type. For example:
+
+ -- limited with P;
+ -- package Pkg is
+ -- type Acc is access P.T;
+ -- end Pkg;
+
+ -- with Pkg; use Acc;
+ -- procedure Example is
+ -- A, B : Acc;
+ -- begin
+ -- A.all := B.all; -- ERROR
+ -- end Example;
+
+ if Nkind (Lhs) = N_Explicit_Dereference
+ and then Ekind (T1) = E_Incomplete_Type
+ then
+ Error_Msg_N ("invalid use of incomplete type", Lhs);
+ Kill_Lhs;
+ return;
+ end if;
+
+ -- Now we can complete the resolution of the right hand side
+
+ Set_Assignment_Type (Lhs, T1);
Resolve (Rhs, T1);
+
+ -- This is the point at which we check for an unset reference
+
Check_Unset_Reference (Rhs);
-- 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;
+ -- Ada 2005 (AI-326): In case of explicit dereference of incomplete
+ -- types, use the non-limited view if available
+
+ if Nkind (Rhs) = N_Explicit_Dereference
+ and then Ekind (T2) = E_Incomplete_Type
+ and then Is_Tagged_Type (T2)
+ and then Present (Non_Limited_View (T2))
+ then
+ T2 := Non_Limited_View (T2);
+ end if;
+
Set_Assignment_Type (Rhs, T2);
if Total_Errors_Detected /= 0 then
end if;
if T1 = Any_Type or else T2 = Any_Type then
+ Kill_Lhs;
return;
end if;
- if (Is_Class_Wide_Type (T2) or else Is_Dynamically_Tagged (Rhs))
+ -- If the rhs is class-wide or dynamically tagged, then require the lhs
+ -- to be class-wide. The case where the rhs is a dynamically tagged call
+ -- to a dispatching operation with a controlling access result is
+ -- excluded from this check, since the target has an access type (and
+ -- no tag propagation occurs in that case).
+
+ if (Is_Class_Wide_Type (T2)
+ or else (Is_Dynamically_Tagged (Rhs)
+ and then not Is_Access_Type (T1)))
and then not Is_Class_Wide_Type (T1)
then
Error_Msg_N ("dynamically tagged expression not allowed!", Rhs);
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)
+ 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
+ -- access type, apply an implicit conversion of the rhs to that type
+ -- to force appropriate static and run-time accessibility checks.
+
+ if Ada_Version >= Ada_05
+ and then Ekind (T1) = E_Anonymous_Access_Type
then
- Propagate_Tag (Lhs, Rhs);
+ Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
+ Analyze_And_Resolve (Rhs, T1);
end if;
-- 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
- Error_Msg_N
- ("(Ada 2005) NULL not allowed in null-excluding objects", Lhs);
+ 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.
- -- We still have a simple assignment statement (no expansion
- -- activity has modified it in some peculiar manner)
+ if Is_Entity_Name (Lhs)
+ and then Nkind (N) = N_Assignment_Statement
+ then
+ declare
+ Ent : constant Entity_Id := Entity (Lhs);
- -- The type is a discrete type
+ 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;
- -- The assignment is to a named entity
+ -- 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 value is known at compile time
+ if Is_Access_Type (T1) then
+ if Known_Non_Null (Rhs) then
+ Set_Is_Known_Non_Null (Ent, True);
- 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;
+ elsif Known_Null (Rhs)
+ and then not Can_Never_Be_Null (Ent)
+ then
+ Set_Is_Known_Null (Ent, True);
+
+ else
+ Set_Is_Known_Null (Ent, False);
- Ent := Entity (Lhs);
+ if not Can_Never_Be_Null (Ent) then
+ Set_Is_Known_Non_Null (Ent, False);
+ end if;
+ end if;
- -- Capture value if save to do so
+ -- For discrete types, we may be able to set the current value
+ -- if the value is known at compile time.
- if Safe_To_Capture_Value (N, Ent) then
- Set_Current_Value (Ent, Rhs);
+ 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;
+
+ -- If not safe to capture values, kill them
+
+ else
+ Kill_Lhs;
+ end if;
+ end;
end if;
end Analyze_Assignment;
procedure Analyze_Block_Statement (N : Node_Id) is
Decls : constant List_Id := Declarations (N);
Id : constant Node_Id := Identifier (N);
- Ent : Entity_Id := Empty;
+ HSS : constant Node_Id := Handled_Statement_Sequence (N);
begin
- -- If a label is present analyze it and mark it as referenced
+ -- If no handled statement sequence is present, things are really
+ -- messed up, and we just return immediately (this is a defence
+ -- against previous errors).
- if Present (Id) then
- Analyze (Id);
- Ent := Entity (Id);
+ if No (HSS) then
+ return;
+ end if;
- -- An error defense. If we have an identifier, but no entity, then
- -- something is wrong. If we have previous errors, then just remove
- -- the identifier and continue, otherwise raise an exception.
+ -- Normal processing with HSS present
- if No (Ent) then
- if Total_Errors_Detected /= 0 then
- Set_Identifier (N, Empty);
- else
- raise Program_Error;
- end if;
+ declare
+ EH : constant List_Id := Exception_Handlers (HSS);
+ Ent : Entity_Id := Empty;
+ S : Entity_Id;
- else
- Set_Ekind (Ent, E_Block);
- Generate_Reference (Ent, N, ' ');
- Generate_Definition (Ent);
+ Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
+ -- Recursively save value of this global, will be restored on exit
- if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
- Set_Label_Construct (Parent (Ent), N);
- end if;
+ begin
+ -- Initialize unblocked exit count for statements of begin block
+ -- plus one for each excption handler that is present.
+
+ Unblocked_Exit_Count := 1;
+
+ if Present (EH) then
+ Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH);
end if;
- end if;
- -- If no entity set, create a label entity
+ -- If a label is present analyze it and mark it as referenced
- if No (Ent) then
- Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B');
- Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N)));
- Set_Parent (Ent, N);
- end if;
+ if Present (Id) then
+ Analyze (Id);
+ Ent := Entity (Id);
- Set_Etype (Ent, Standard_Void_Type);
- Set_Block_Node (Ent, Identifier (N));
- New_Scope (Ent);
+ -- An error defense. If we have an identifier, but no entity,
+ -- then something is wrong. If we have previous errors, then
+ -- just remove the identifier and continue, otherwise raise
+ -- an exception.
- if Present (Decls) then
- Analyze_Declarations (Decls);
- Check_Completion;
- end if;
+ if No (Ent) then
+ if Total_Errors_Detected /= 0 then
+ Set_Identifier (N, Empty);
+ else
+ raise Program_Error;
+ end if;
- Analyze (Handled_Statement_Sequence (N));
- Process_End_Label (Handled_Statement_Sequence (N), 'e', Ent);
+ else
+ Set_Ekind (Ent, E_Block);
+ Generate_Reference (Ent, N, ' ');
+ Generate_Definition (Ent);
- -- Analyze exception handlers if present. Note that the test for
- -- HSS being present is an error defence against previous errors.
+ if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
+ Set_Label_Construct (Parent (Ent), N);
+ end if;
+ end if;
+ end if;
- if Present (Handled_Statement_Sequence (N))
- and then Present (Exception_Handlers (Handled_Statement_Sequence (N)))
- then
- declare
- S : Entity_Id := Scope (Ent);
+ -- If no entity set, create a label entity
- begin
- -- Indicate that enclosing scopes contain a block with handlers.
- -- Only non-generic scopes need to be marked.
+ if No (Ent) then
+ Ent := New_Internal_Entity (E_Block, Current_Scope, Sloc (N), 'B');
+ Set_Identifier (N, New_Occurrence_Of (Ent, Sloc (N)));
+ Set_Parent (Ent, N);
+ end if;
+
+ Set_Etype (Ent, Standard_Void_Type);
+ Set_Block_Node (Ent, Identifier (N));
+ Push_Scope (Ent);
+
+ if Present (Decls) then
+ Analyze_Declarations (Decls);
+ Check_Completion;
+ end if;
+
+ Analyze (HSS);
+ Process_End_Label (HSS, 'e', Ent);
+
+ -- If exception handlers are present, then we indicate that
+ -- enclosing scopes contain a block with handlers. We only
+ -- need to mark non-generic scopes.
+ if Present (EH) then
+ S := Scope (Ent);
loop
Set_Has_Nested_Block_With_Handler (S);
exit when Is_Overloadable (S)
or else Is_Generic_Unit (S);
S := Scope (S);
end loop;
- end;
- end if;
+ end if;
- Check_References (Ent);
- End_Scope;
+ Check_References (Ent);
+ Warn_On_Useless_Assignments (Ent);
+ End_Scope;
+
+ if Unblocked_Exit_Count = 0 then
+ Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
+ Check_Unreachable_Code (N);
+ else
+ Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
+ end if;
+ end;
end Analyze_Block_Statement;
----------------------------
begin
Unblocked_Exit_Count := 0;
Exp := Expression (N);
- Analyze_And_Resolve (Exp, Any_Discrete);
+ Analyze (Exp);
+
+ -- The expression must be of any discrete type. In rare cases, the
+ -- expander constructs a case statement whose expression has a private
+ -- type whose full view is discrete. This can happen when generating
+ -- a stream operation for a variant type after the type is frozen,
+ -- when the partial of view of the type of the discriminant is private.
+ -- In that case, use the full view to analyze case alternatives.
+
+ if not Is_Overloaded (Exp)
+ and then not Comes_From_Source (N)
+ and then Is_Private_Type (Etype (Exp))
+ and then Present (Full_View (Etype (Exp)))
+ and then Is_Discrete_Type (Full_View (Etype (Exp)))
+ then
+ Resolve (Exp, Etype (Exp));
+ Exp_Type := Full_View (Etype (Exp));
+
+ else
+ Analyze_And_Resolve (Exp, Any_Discrete);
+ Exp_Type := Etype (Exp);
+ end if;
+
Check_Unset_Reference (Exp);
- Exp_Type := Etype (Exp);
Exp_Btype := Base_Type (Exp_Type);
-- The expression must be of a discrete type which must be determinable
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
-- Analyze_If_Statement --
--------------------------
- -- A special complication arises in the analysis of if statements.
+ -- A special complication arises in the analysis of if statements
-- The expander has circuitry to completely delete code that it
-- can tell will not be executed (as a result of compile time known
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
------------------------------
procedure Analyze_Iteration_Scheme (N : Node_Id) is
+
+ procedure Process_Bounds (R : Node_Id);
+ -- If the iteration is given by a range, create temporaries and
+ -- assignment statements block to capture the bounds and perform
+ -- required finalization actions in case a bound includes a function
+ -- call that uses the temporary stack. We first pre-analyze a copy of
+ -- the range in order to determine the expected type, and analyze and
+ -- resolve the original bounds.
+
procedure Check_Controlled_Array_Attribute (DS : Node_Id);
-- If the bounds are given by a 'Range reference on a function call
-- that returns a controlled array, introduce an explicit declaration
-- to capture the bounds, so that the function result can be finalized
-- in timely fashion.
+ --------------------
+ -- Process_Bounds --
+ --------------------
+
+ procedure Process_Bounds (R : Node_Id) is
+ Loc : constant Source_Ptr := Sloc (N);
+ R_Copy : constant Node_Id := New_Copy_Tree (R);
+ Lo : constant Node_Id := Low_Bound (R);
+ Hi : constant Node_Id := High_Bound (R);
+ 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;
+ Analyzed_Bound : Node_Id) return Node_Id;
+ -- Create one declaration followed by one assignment statement
+ -- to capture the value of bound. We create a separate assignment
+ -- in order to force the creation of a block in case the bound
+ -- contains a call that uses the secondary stack.
+
+ ---------------
+ -- One_Bound --
+ ---------------
+
+ function One_Bound
+ (Original_Bound : Node_Id;
+ Analyzed_Bound : Node_Id) return Node_Id
+ is
+ Assign : Node_Id;
+ Id : Entity_Id;
+ Decl : Node_Id;
+
+ begin
+ -- If the bound is a constant or an object, no need for a separate
+ -- declaration. If the bound is the result of previous expansion
+ -- it is already analyzed and should not be modified. Note that
+ -- the Bound will be resolved later, if needed, as part of the
+ -- call to Make_Index (literal bounds may need to be resolved to
+ -- type Integer).
+
+ if Analyzed (Original_Bound) then
+ return Original_Bound;
+
+ elsif Nkind (Analyzed_Bound) = N_Integer_Literal
+ or else Nkind (Analyzed_Bound) = N_Character_Literal
+ or else Is_Entity_Name (Analyzed_Bound)
+ then
+ Analyze_And_Resolve (Original_Bound, Typ);
+ return Original_Bound;
+
+ else
+ Analyze_And_Resolve (Original_Bound, Typ);
+ end if;
+
+ Id :=
+ Make_Defining_Identifier (Loc,
+ Chars => New_Internal_Name ('S'));
+
+ Decl :=
+ Make_Object_Declaration (Loc,
+ Defining_Identifier => Id,
+ Object_Definition => New_Occurrence_Of (Typ, Loc));
+
+ Insert_Before (Parent (N), Decl);
+ Analyze (Decl);
+
+ Assign :=
+ Make_Assignment_Statement (Loc,
+ Name => New_Occurrence_Of (Id, Loc),
+ Expression => Relocate_Node (Original_Bound));
+
+ Insert_Before (Parent (N), Assign);
+ Analyze (Assign);
+
+ Rewrite (Original_Bound, New_Occurrence_Of (Id, Loc));
+
+ if Nkind (Assign) = N_Assignment_Statement then
+ return Expression (Assign);
+ else
+ return Original_Bound;
+ end if;
+ end One_Bound;
+
+ -- Start of processing for Process_Bounds
+
+ begin
+ -- 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));
+ 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, unless the
+ -- literal bounds are constant-folded expressions that carry a user-
+ -- defined type.
+
+ if Typ = Universal_Integer then
+ 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);
+
+ New_Lo_Bound := One_Bound (Lo, Low_Bound (R_Copy));
+ New_Hi_Bound := One_Bound (Hi, High_Bound (R_Copy));
+
+ -- Propagate staticness to loop range itself, in case the
+ -- corresponding subtype is static.
+
+ if New_Lo_Bound /= Lo
+ and then Is_Static_Expression (New_Lo_Bound)
+ then
+ Rewrite (Low_Bound (R), New_Copy (New_Lo_Bound));
+ end if;
+
+ if New_Hi_Bound /= Hi
+ and then Is_Static_Expression (New_Hi_Bound)
+ then
+ Rewrite (High_Bound (R), New_Copy (New_Hi_Bound));
+ end if;
+ end Process_Bounds;
+
--------------------------------------
-- Check_Controlled_Array_Attribute --
--------------------------------------
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
end if;
end;
- -- Now analyze the subtype definition
+ -- Now analyze the subtype definition. If it is
+ -- a range, create temporaries for bounds.
- Analyze (DS);
+ if Nkind (DS) = N_Range
+ and then Expander_Active
+ then
+ Process_Bounds (DS);
+ else
+ Analyze (DS);
+ end if;
if DS = Error then
return;
end if;
Check_Controlled_Array_Attribute (DS);
+
Make_Index (DS, LP);
Set_Ekind (Id, E_Loop_Parameter);
-- 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;
+ Loop_Statement : constant Node_Id := N;
+
+ Id : constant Node_Id := Identifier (Loop_Statement);
+ Iter : constant Node_Id := Iteration_Scheme (Loop_Statement);
+ Ent : Entity_Id;
begin
if Present (Id) then
Analyze (Id);
Ent := Entity (Id);
- Generate_Reference (Ent, N, ' ');
+ Generate_Reference (Ent, Loop_Statement, ' ');
Generate_Definition (Ent);
-- If we found a label, mark its type. If not, ignore it, since it
Set_Ekind (Ent, E_Loop);
if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
- Set_Label_Construct (Parent (Ent), N);
+ Set_Label_Construct (Parent (Ent), Loop_Statement);
end if;
end if;
-- Case of no identifier present
else
- Ent := New_Internal_Entity (E_Loop, Current_Scope, Sloc (N), 'L');
+ Ent :=
+ New_Internal_Entity
+ (E_Loop, Current_Scope, Sloc (Loop_Statement), 'L');
Set_Etype (Ent, Standard_Void_Type);
- Set_Parent (Ent, N);
+ Set_Parent (Ent, Loop_Statement);
end if;
-- Kill current values on entry to loop, since statements in body
-- that the body of the loop was executed.
Kill_Current_Values;
- New_Scope (Ent);
- Analyze_Iteration_Scheme (Iteration_Scheme (N));
- Analyze_Statements (Statements (N));
- Process_End_Label (N, 'e', Ent);
+ Push_Scope (Ent);
+ Analyze_Iteration_Scheme (Iter);
+ Analyze_Statements (Statements (Loop_Statement));
+ Process_End_Label (Loop_Statement, 'e', Ent);
End_Scope;
Kill_Current_Values;
+ Check_Infinite_Loop_Warning (N);
end Analyze_Loop_Statement;
----------------------------
Analyze (Identifier (S));
Lab := Entity (Identifier (S));
- -- If we found a label mark it as reachable.
+ -- If we found a label mark it as reachable
if Ekind (Lab) = E_Label then
Generate_Definition (Lab);
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 --
----------------------------
begin
Nxt := Original_Node (Next (N));
- if Present (Nxt)
+ -- If a label follows us, then we never have dead code, since
+ -- someone could branch to the label, so we just ignore it.
+
+ if Nkind (Nxt) = N_Label then
+ return;
+
+ -- Otherwise see if we have a real statement following us
+
+ elsif Present (Nxt)
and then Comes_From_Source (Nxt)
and then Is_Statement (Nxt)
then
-- The rather strange shenanigans with the warning message
-- here reflects the fact that Kill_Dead_Code is very good
-- at removing warnings in deleted code, and this is one
- -- warning we would prefer NOT to have removed :-)
+ -- warning we would prefer NOT to have removed.
Error_Loc := Sloc (Nxt);
-- If the unconditional transfer of control instruction is
-- the last statement of a sequence, then see if our parent
- -- is an IF statement, and if so adjust the unblocked exit
- -- count of the if statement to reflect the fact that this
- -- branch of the if is indeed blocked by a transfer of control.
+ -- is one of the constructs for which we count unblocked exits,
+ -- and if so, adjust the count.
else
P := Parent (N);
+ -- Statements in THEN part or ELSE part of IF statement
+
if Nkind (P) = N_If_Statement then
null;
+ -- Statements in ELSIF part of an IF statement
+
elsif Nkind (P) = N_Elsif_Part then
P := Parent (P);
pragma Assert (Nkind (P) = N_If_Statement);
+ -- Statements in CASE statement alternative
+
elsif Nkind (P) = N_Case_Statement_Alternative then
P := Parent (P);
pragma Assert (Nkind (P) = N_Case_Statement);
+ -- Statements in body of block
+
+ elsif Nkind (P) = N_Handled_Sequence_Of_Statements
+ and then Nkind (Parent (P)) = N_Block_Statement
+ then
+ null;
+
+ -- Statements in exception handler in a block
+
+ elsif Nkind (P) = N_Exception_Handler
+ and then Nkind (Parent (P)) = N_Handled_Sequence_Of_Statements
+ and then Nkind (Parent (Parent (P))) = N_Block_Statement
+ then
+ null;
+
+ -- None of these cases, so return
+
else
return;
end if;
+ -- This was one of the cases we are looking for (i.e. the
+ -- parent construct was IF, CASE or block) so decrement count.
+
Unblocked_Exit_Count := Unblocked_Exit_Count - 1;
end if;
end;
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