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------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S E M _ C H 5 --
-- --
-- B o d y --
-- --
-- Copyright (C) 1992-2013, 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- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- 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 COPYING3. If not, go to --
-- http://www.gnu.org/licenses for a complete copy of the license. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
with Aspects; use Aspects;
with Atree; use Atree;
with Checks; use Checks;
with Einfo; use Einfo;
with Errout; use Errout;
with Expander; use Expander;
with Exp_Ch6; use Exp_Ch6;
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 Restrict; use Restrict;
with Rident; use Rident;
with Rtsfind; use Rtsfind;
with Sem; use Sem;
with Sem_Aux; use Sem_Aux;
with Sem_Case; use Sem_Case;
with Sem_Ch3; use Sem_Ch3;
with Sem_Ch6; use Sem_Ch6;
with Sem_Ch8; use Sem_Ch8;
with Sem_Dim; use Sem_Dim;
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;
with Tbuild; use Tbuild;
with Uintp; use Uintp;
package body Sem_Ch5 is
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 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.
procedure Preanalyze_Range (R_Copy : Node_Id);
-- Determine expected type of range or domain of iteration of Ada 2012
-- loop by analyzing separate copy. Do the analysis and resolution of the
-- copy of the bound(s) with expansion disabled, to prevent the generation
-- of finalization actions. This prevents memory leaks when the bounds
-- contain calls to functions returning controlled arrays or when the
-- domain of iteration is a container.
------------------------
-- Analyze_Assignment --
------------------------
procedure Analyze_Assignment (N : Node_Id) is
Lhs : constant Node_Id := Name (N);
Rhs : constant Node_Id := Expression (N);
T1 : Entity_Id;
T2 : Entity_Id;
Decl : Node_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);
-- Opnd is either the Lhs or Rhs of the assignment, and Opnd_Type is the
-- nominal subtype. This procedure is used to deal with cases where the
-- nominal subtype must be replaced by the actual subtype.
-------------------------------
-- Diagnose_Non_Variable_Lhs --
-------------------------------
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.
if Error_Posted (N) then
return;
-- Some special bad cases of entity names
elsif Is_Entity_Name (N) then
declare
Ent : constant Entity_Id := Entity (N);
begin
if Ekind (Ent) = E_In_Parameter then
Error_Msg_N
("assignment to IN mode parameter not allowed", N);
-- Renamings of protected private components are turned into
-- constants when compiling a protected function. In the case
-- of single protected types, the private component appears
-- directly.
elsif (Is_Prival (Ent)
and then
(Ekind (Current_Scope) = E_Function
or else Ekind (Enclosing_Dynamic_Scope
(Current_Scope)) = E_Function))
or else
(Ekind (Ent) = E_Component
and then Is_Protected_Type (Scope (Ent)))
then
Error_Msg_N
("protected function cannot modify protected object", N);
elsif Ekind (Ent) = E_Loop_Parameter then
Error_Msg_N
("assignment to loop parameter not allowed", N);
else
Error_Msg_N
("left hand side of assignment must be a variable", N);
end if;
end;
-- For indexed components or selected components, test prefix
elsif Nkind (N) = N_Indexed_Component then
Diagnose_Non_Variable_Lhs (Prefix (N));
-- Another special case for assignment to discriminant
elsif Nkind (N) = N_Selected_Component then
if Present (Entity (Selector_Name (N)))
and then Ekind (Entity (Selector_Name (N))) = E_Discriminant
then
Error_Msg_N
("assignment to discriminant not allowed", N);
else
Diagnose_Non_Variable_Lhs (Prefix (N));
end if;
else
-- If we fall through, we have no special message to issue!
Error_Msg_N ("left hand side of assignment must be a variable", 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 --
-------------------------
procedure Set_Assignment_Type
(Opnd : Node_Id;
Opnd_Type : in out Entity_Id)
is
begin
Require_Entity (Opnd);
-- If the assignment operand is an in-out or out parameter, then we
-- get the actual subtype (needed for the unconstrained case). If the
-- operand is the actual in an entry declaration, then within the
-- accept statement it is replaced with a local renaming, which may
-- also have an actual subtype.
if Is_Entity_Name (Opnd)
and then (Ekind (Entity (Opnd)) = E_Out_Parameter
or else Ekind (Entity (Opnd)) =
E_In_Out_Parameter
or else Ekind (Entity (Opnd)) =
E_Generic_In_Out_Parameter
or else
(Ekind (Entity (Opnd)) = E_Variable
and then Nkind (Parent (Entity (Opnd))) =
N_Object_Renaming_Declaration
and then Nkind (Parent (Parent (Entity (Opnd)))) =
N_Accept_Statement))
then
Opnd_Type := Get_Actual_Subtype (Opnd);
-- If assignment operand is a component reference, then we get the
-- actual subtype of the component for the unconstrained case.
elsif Nkind_In (Opnd, N_Selected_Component, N_Explicit_Dereference)
and then not Is_Unchecked_Union (Opnd_Type)
then
Decl := Build_Actual_Subtype_Of_Component (Opnd_Type, Opnd);
if Present (Decl) then
Insert_Action (N, Decl);
Mark_Rewrite_Insertion (Decl);
Analyze (Decl);
Opnd_Type := Defining_Identifier (Decl);
Set_Etype (Opnd, Opnd_Type);
Freeze_Itype (Opnd_Type, N);
elsif Is_Constrained (Etype (Opnd)) then
Opnd_Type := Etype (Opnd);
end if;
-- For slice, use the constrained subtype created for the slice
elsif Nkind (Opnd) = N_Slice then
Opnd_Type := Etype (Opnd);
end if;
end Set_Assignment_Type;
-- Start of processing for Analyze_Assignment
begin
Mark_Coextensions (N, Rhs);
Analyze (Rhs);
Analyze (Lhs);
-- Ensure that we never do an assignment on a variable marked as
-- as Safe_To_Reevaluate.
pragma Assert (not Is_Entity_Name (Lhs)
or else Ekind (Entity (Lhs)) /= E_Variable
or else not Is_Safe_To_Reevaluate (Entity (Lhs)));
-- Start type analysis for assignment
T1 := Etype (Lhs);
-- In the most general case, both Lhs and Rhs can be overloaded, and we
-- must compute the intersection of the possible types on each side.
if Is_Overloaded (Lhs) then
declare
I : Interp_Index;
It : Interp;
begin
T1 := Any_Type;
Get_First_Interp (Lhs, I, It);
while Present (It.Typ) loop
if Has_Compatible_Type (Rhs, It.Typ) then
if T1 /= Any_Type then
-- An explicit dereference is overloaded if the prefix
-- is. Try to remove the ambiguity on the prefix, the
-- error will be posted there if the ambiguity is real.
if Nkind (Lhs) = N_Explicit_Dereference then
declare
PI : Interp_Index;
PI1 : Interp_Index := 0;
PIt : Interp;
Found : Boolean;
begin
Found := False;
Get_First_Interp (Prefix (Lhs), PI, PIt);
while Present (PIt.Typ) loop
if Is_Access_Type (PIt.Typ)
and then Has_Compatible_Type
(Rhs, Designated_Type (PIt.Typ))
then
if Found then
PIt :=
Disambiguate (Prefix (Lhs),
PI1, PI, Any_Type);
if PIt = No_Interp then
Error_Msg_N
("ambiguous left-hand side"
& " in assignment", Lhs);
exit;
else
Resolve (Prefix (Lhs), PIt.Typ);
end if;
exit;
else
Found := True;
PI1 := PI;
end if;
end if;
Get_Next_Interp (PI, PIt);
end loop;
end;
else
Error_Msg_N
("ambiguous left-hand side in assignment", Lhs);
exit;
end if;
else
T1 := It.Typ;
end if;
end if;
Get_Next_Interp (I, It);
end loop;
end;
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_2005 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
-- CPP constructors can only be called in declarations
if Is_CPP_Constructor_Call (Rhs) then
Error_Msg_N ("invalid use of 'C'P'P constructor", Rhs);
else
Error_Msg_N
("left hand of assignment must not be limited type", Lhs);
Explain_Limited_Type (T1, Lhs);
end if;
return;
-- Enforce RM 3.9.3 (8): the target of an assignment operation cannot be
-- abstract. This is only checked when the assignment Comes_From_Source,
-- because in some cases the expander generates such assignments (such
-- in the _assign operation for an abstract type).
elsif Is_Abstract_Type (T1) and then Comes_From_Source (N) then
Error_Msg_N
("target of assignment operation must not be abstract", Lhs);
end if;
-- Resolution may have updated the subtype, in case the left-hand side
-- is a private protected component. Use the correct subtype to avoid
-- scoping issues in the back-end.
T1 := Etype (Lhs);
-- 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);
Check_Unprotected_Access (Lhs, Rhs);
-- Remaining steps are skipped if Rhs was syntactically in error
if Rhs = Error then
Kill_Lhs;
return;
end if;
T2 := Etype (Rhs);
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
if No (T1) then
T1 := Any_Type;
end if;
if No (T2) then
T2 := Any_Type;
end if;
end if;
if T1 = Any_Type or else T2 = Any_Type then
Kill_Lhs;
return;
end if;
-- 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);
elsif Is_Class_Wide_Type (T1)
and then not Is_Class_Wide_Type (T2)
and then not Is_Tag_Indeterminate (Rhs)
and then not Is_Dynamically_Tagged (Rhs)
then
Error_Msg_N ("dynamically tagged expression required!", Rhs);
end if;
-- Propagate the tag from a class-wide target to the rhs when the rhs
-- is a tag-indeterminate call.
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-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. This applies
-- as well to anonymous access-to-subprogram types that are component
-- subtypes or formal parameters.
if Ada_Version >= Ada_2005
and then Is_Access_Type (T1)
then
if Is_Local_Anonymous_Access (T1)
or else Ekind (T2) = E_Anonymous_Access_Subprogram_Type
-- Handle assignment to an Ada 2012 stand-alone object
-- of an anonymous access type.
or else (Ekind (T1) = E_Anonymous_Access_Type
and then Nkind (Associated_Node_For_Itype (T1)) =
N_Object_Declaration)
then
Rewrite (Rhs, Convert_To (T1, Relocate_Node (Rhs)));
Analyze_And_Resolve (Rhs, T1);
end if;
end if;
-- Ada 2005 (AI-231): Assignment to not null variable
if Ada_Version >= Ada_2005
and then Can_Never_Be_Null (T1)
and then not Assignment_OK (Lhs)
then
-- Case where we know the right hand side is null
if Known_Null (Rhs) then
Apply_Compile_Time_Constraint_Error
(N => Rhs,
Msg =>
"(Ada 2005) null not allowed in null-excluding objects??",
Reason => CE_Null_Not_Allowed);
-- We still mark this as a possible modification, that's necessary
-- to reset Is_True_Constant, and desirable for xref purposes.
Note_Possible_Modification (Lhs, Sure => True);
return;
-- If we know the right hand side is non-null, then we convert to the
-- target type, since we don't need a run time check in that case.
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
-- is 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)))
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 indexes do not have to match. If the right-hand
-- side is a type conversion to an unconstrained type, a length check
-- is performed on the expression itself during expansion. In rare
-- cases, the redundant length check is computed on an index type
-- with a different representation, triggering incorrect code in the
-- back end.
Apply_Length_Check (Rhs, Etype (Lhs));
else
-- Discriminant checks are applied in the course of expansion
null;
end if;
-- Note: modifications of the Lhs may only be recorded after
-- checks have been applied.
Note_Possible_Modification (Lhs, Sure => True);
-- ??? a real accessibility check is needed when ???
-- Post warning for redundant assignment or variable to itself
if Warn_On_Redundant_Constructs
-- We only warn for source constructs
and then Comes_From_Source (N)
-- Where the object is the same on both sides
and then Same_Object (Lhs, Original_Node (Rhs))
-- But exclude the case where the right side was an operation that
-- got rewritten (e.g. JUNK + K, where K was known to be zero). We
-- don't want to warn in such a case, since it is reasonable to write
-- such expressions especially when K is defined symbolically in some
-- other package.
and then Nkind (Original_Node (Rhs)) not in N_Op
then
if Nkind (Lhs) in N_Has_Entity then
Error_Msg_NE -- CODEFIX
("?r?useless assignment of & to itself!", N, Entity (Lhs));
else
Error_Msg_N -- CODEFIX
("?r?useless assignment of object to itself!", N);
end if;
end if;
-- Check for non-allowed composite assignment
if not Support_Composite_Assign_On_Target
and then (Is_Array_Type (T1) or else Is_Record_Type (T1))
and then (not Has_Size_Clause (T1) or else Esize (T1) > 64)
then
Error_Msg_CRT ("composite assignment", N);
end if;
-- 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;
-- Set Referenced_As_LHS if appropriate. We only set this flag if the
-- assignment is a source assignment in the extended main source unit.
-- We are not interested in any reference information outside this
-- context, or in compiler generated assignment statements.
if Comes_From_Source (N)
and then In_Extended_Main_Source_Unit (Lhs)
then
Set_Referenced_Modified (Lhs, Out_Param => False);
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). 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 Is_Assignable (Ent)
and then Comes_From_Source (N)
and then In_Extended_Main_Source_Unit (Ent)
then
Warn_On_Useless_Assignment (Ent, N);
end if;
-- 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.
if Is_Access_Type (T1) then
if Known_Non_Null (Rhs) then
Set_Is_Known_Non_Null (Ent, True);
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);
if not Can_Never_Be_Null (Ent) then
Set_Is_Known_Non_Null (Ent, False);
end if;
end if;
-- 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;
-- If not safe to capture values, kill them
else
Kill_Lhs;
end if;
end;
end if;
-- If assigning to an object in whole or in part, 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.
declare
Ent : constant Entity_Id := Get_Enclosing_Object (Lhs);
begin
if Present (Ent)
and then Safe_To_Capture_Value (N, Ent)
and then Nkind (N) = N_Assignment_Statement
and then Warn_On_Modified_Unread
and then Is_Assignable (Ent)
and then Comes_From_Source (N)
and then In_Extended_Main_Source_Unit (Ent)
then
Set_Last_Assignment (Ent, Lhs);
end if;
end;
Analyze_Dimension (N);
end Analyze_Assignment;
-----------------------------
-- Analyze_Block_Statement --
-----------------------------
procedure Analyze_Block_Statement (N : Node_Id) is
procedure Install_Return_Entities (Scop : Entity_Id);
-- Install all entities of return statement scope Scop in the visibility
-- chain except for the return object since its entity is reused in a
-- renaming.
-----------------------------
-- Install_Return_Entities --
-----------------------------
procedure Install_Return_Entities (Scop : Entity_Id) is
Id : Entity_Id;
begin
Id := First_Entity (Scop);
while Present (Id) loop
-- Do not install the return object
if not Ekind_In (Id, E_Constant, E_Variable)
or else not Is_Return_Object (Id)
then
Install_Entity (Id);
end if;
Next_Entity (Id);
end loop;
end Install_Return_Entities;
-- Local constants and variables
Decls : constant List_Id := Declarations (N);
Id : constant Node_Id := Identifier (N);
HSS : constant Node_Id := Handled_Statement_Sequence (N);
Is_BIP_Return_Statement : Boolean;
-- Start of processing for Analyze_Block_Statement
begin
-- In SPARK mode, we reject block statements. Note that the case of
-- block statements generated by the expander is fine.
if Nkind (Original_Node (N)) = N_Block_Statement then
Check_SPARK_Restriction ("block statement is not allowed", N);
end if;
-- If no handled statement sequence is present, things are really messed
-- up, and we just return immediately (defence against previous errors).
if No (HSS) then
Check_Error_Detected;
return;
end if;
-- Detect whether the block is actually a rewritten return statement of
-- a build-in-place function.
Is_BIP_Return_Statement :=
Present (Id)
and then Present (Entity (Id))
and then Ekind (Entity (Id)) = E_Return_Statement
and then Is_Build_In_Place_Function
(Return_Applies_To (Entity (Id)));
-- Normal processing with HSS present
declare
EH : constant List_Id := Exception_Handlers (HSS);
Ent : Entity_Id := Empty;
S : Entity_Id;
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
begin
-- Initialize unblocked exit count for statements of begin block
-- plus one for each exception handler that is present.
Unblocked_Exit_Count := 1;
if Present (EH) then
Unblocked_Exit_Count := Unblocked_Exit_Count + List_Length (EH);
end if;
-- If a label is present analyze it and mark it as referenced
if Present (Id) then
Analyze (Id);
Ent := Entity (Id);
-- An error defense. If we have an identifier, but no entity, then
-- something is wrong. If previous errors, then just remove the
-- identifier and continue, otherwise raise an exception.
if No (Ent) then
Check_Error_Detected;
Set_Identifier (N, Empty);
else
Set_Ekind (Ent, E_Block);
Generate_Reference (Ent, N, ' ');
Generate_Definition (Ent);
if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
Set_Label_Construct (Parent (Ent), N);
end if;
end if;
end if;
-- If no entity set, create a label entity
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);
-- The block served as an extended return statement. Ensure that any
-- entities created during the analysis and expansion of the return
-- object declaration are once again visible.
if Is_BIP_Return_Statement then
Install_Return_Entities (Ent);
end if;
if Present (Decls) then
Analyze_Declarations (Decls);
Check_Completion;
Inspect_Deferred_Constant_Completion (Decls);
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 Ekind (S) = E_Package
or else Is_Generic_Unit (S);
S := Scope (S);
end loop;
end if;
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;
----------------------------
-- Analyze_Case_Statement --
----------------------------
procedure Analyze_Case_Statement (N : Node_Id) is
Exp : Node_Id;
Exp_Type : Entity_Id;
Exp_Btype : Entity_Id;
Last_Choice : Nat;
Dont_Care : Boolean;
Others_Present : Boolean;
pragma Warnings (Off, Last_Choice);
pragma Warnings (Off, Dont_Care);
-- Don't care about assigned values
Statements_Analyzed : Boolean := False;
-- Set True if at least some statement sequences get analyzed. If False
-- on exit, means we had a serious error that prevented full analysis of
-- the case statement, and as a result it is not a good idea to output
-- warning messages about unreachable code.
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
procedure Non_Static_Choice_Error (Choice : Node_Id);
-- Error routine invoked by the generic instantiation below when the
-- case statement has a non static choice.
procedure Process_Statements (Alternative : Node_Id);
-- Analyzes all the statements associated with a case alternative.
-- Needed by the generic instantiation below.
package Case_Choices_Processing is new
Generic_Choices_Processing
(Get_Alternatives => Alternatives,
Get_Choices => Discrete_Choices,
Process_Empty_Choice => No_OP,
Process_Non_Static_Choice => Non_Static_Choice_Error,
Process_Associated_Node => Process_Statements);
use Case_Choices_Processing;
-- Instantiation of the generic choice processing package
-----------------------------
-- Non_Static_Choice_Error --
-----------------------------
procedure Non_Static_Choice_Error (Choice : Node_Id) is
begin
Flag_Non_Static_Expr
("choice given in case statement is not static!", Choice);
end Non_Static_Choice_Error;
------------------------
-- Process_Statements --
------------------------
procedure Process_Statements (Alternative : Node_Id) is
Choices : constant List_Id := Discrete_Choices (Alternative);
Ent : Entity_Id;
begin
Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
Statements_Analyzed := True;
-- An interesting optimization. If the case statement expression
-- is a simple entity, then we can set the current value within an
-- alternative if the alternative has one possible value.
-- case N is
-- when 1 => alpha
-- when 2 | 3 => beta
-- when others => gamma
-- Here we know that N is initially 1 within alpha, but for beta and
-- gamma, we do not know anything more about the initial value.
if Is_Entity_Name (Exp) then
Ent := Entity (Exp);
if Ekind_In (Ent, E_Variable,
E_In_Out_Parameter,
E_Out_Parameter)
then
if List_Length (Choices) = 1
and then Nkind (First (Choices)) in N_Subexpr
and then Compile_Time_Known_Value (First (Choices))
then
Set_Current_Value (Entity (Exp), First (Choices));
end if;
Analyze_Statements (Statements (Alternative));
-- After analyzing the case, set the current value to empty
-- since we won't know what it is for the next alternative
-- (unless reset by this same circuit), or after the case.
Set_Current_Value (Entity (Exp), Empty);
return;
end if;
end if;
-- Case where expression is not an entity name of a variable
Analyze_Statements (Statements (Alternative));
end Process_Statements;
-- Start of processing for Analyze_Case_Statement
begin
Unblocked_Exit_Count := 0;
Exp := Expression (N);
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_Btype := Base_Type (Exp_Type);
-- The expression must be of a discrete type which must be determinable
-- independently of the context in which the expression occurs, but
-- using the fact that the expression must be of a discrete type.
-- Moreover, the type this expression must not be a character literal
-- (which is always ambiguous) or, for Ada-83, a generic formal type.
-- If error already reported by Resolve, nothing more to do
if Exp_Btype = Any_Discrete
or else Exp_Btype = Any_Type
then
return;
elsif Exp_Btype = Any_Character then
Error_Msg_N
("character literal as case expression is ambiguous", Exp);
return;
elsif Ada_Version = Ada_83
and then (Is_Generic_Type (Exp_Btype)
or else Is_Generic_Type (Root_Type (Exp_Btype)))
then
Error_Msg_N
("(Ada 83) case expression cannot be of a generic type", Exp);
return;
end if;
-- If the case expression is a formal object of mode in out, then treat
-- it as having a nonstatic subtype by forcing use of the base type
-- (which has to get passed to Check_Case_Choices below). Also use base
-- type when the case expression is parenthesized.
if Paren_Count (Exp) > 0
or else (Is_Entity_Name (Exp)
and then Ekind (Entity (Exp)) = E_Generic_In_Out_Parameter)
then
Exp_Type := Exp_Btype;
end if;
-- Call instantiated Analyze_Choices which does the rest of the work
Analyze_Choices (N, Exp_Type, Dont_Care, Others_Present);
-- A case statement with a single OTHERS alternative is not allowed
-- in SPARK.
if Others_Present
and then List_Length (Alternatives (N)) = 1
then
Check_SPARK_Restriction
("OTHERS as unique case alternative is not allowed", N);
end if;
if Exp_Type = Universal_Integer and then not Others_Present then
Error_Msg_N ("case on universal integer requires OTHERS choice", Exp);
end if;
-- If all our exits were blocked by unconditional transfers of control,
-- then the entire CASE statement acts as an unconditional transfer of
-- control, so treat it like one, and check unreachable code. Skip this
-- test if we had serious errors preventing any statement analysis.
if Unblocked_Exit_Count = 0 and then Statements_Analyzed then
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
Check_Unreachable_Code (N);
else
Unblocked_Exit_Count := Save_Unblocked_Exit_Count;
end if;
if not Expander_Active
and then Compile_Time_Known_Value (Expression (N))
and then Serious_Errors_Detected = 0
then
declare
Chosen : constant Node_Id := Find_Static_Alternative (N);
Alt : Node_Id;
begin
Alt := First (Alternatives (N));
while Present (Alt) loop
if Alt /= Chosen then
Remove_Warning_Messages (Statements (Alt));
end if;
Next (Alt);
end loop;
end;
end if;
end Analyze_Case_Statement;
----------------------------
-- Analyze_Exit_Statement --
----------------------------
-- If the exit includes a name, it must be the name of a currently open
-- loop. Otherwise there must be an innermost open loop on the stack, to
-- which the statement implicitly refers.
-- Additionally, in SPARK mode:
-- The exit can only name the closest enclosing loop;
-- An exit with a when clause must be directly contained in a loop;
-- An exit without a when clause must be directly contained in an
-- if-statement with no elsif or else, which is itself directly contained
-- in a loop. The exit must be the last statement in the if-statement.
procedure Analyze_Exit_Statement (N : Node_Id) is
Target : constant Node_Id := Name (N);
Cond : constant Node_Id := Condition (N);
Scope_Id : Entity_Id;
U_Name : Entity_Id;
Kind : Entity_Kind;
begin
if No (Cond) then
Check_Unreachable_Code (N);
end if;
if Present (Target) then
Analyze (Target);
U_Name := Entity (Target);
if not In_Open_Scopes (U_Name) or else Ekind (U_Name) /= E_Loop then
Error_Msg_N ("invalid loop name in exit statement", N);
return;
else
if Has_Loop_In_Inner_Open_Scopes (U_Name) then
Check_SPARK_Restriction
("exit label must name the closest enclosing loop", N);
end if;
Set_Has_Exit (U_Name);
end if;
else
U_Name := Empty;
end if;
for J in reverse 0 .. Scope_Stack.Last loop
Scope_Id := Scope_Stack.Table (J).Entity;
Kind := Ekind (Scope_Id);
if Kind = E_Loop
and then (No (Target) or else Scope_Id = U_Name)
then
Set_Has_Exit (Scope_Id);
exit;
elsif Kind = E_Block
or else Kind = E_Loop
or else Kind = E_Return_Statement
then
null;
else
Error_Msg_N
("cannot exit from program unit or accept statement", N);
return;
end if;
end loop;
-- Verify that if present the condition is a Boolean expression
if Present (Cond) then
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
end if;
-- In SPARK mode, verify that the exit statement respects the SPARK
-- restrictions.
if Present (Cond) then
if Nkind (Parent (N)) /= N_Loop_Statement then
Check_SPARK_Restriction
("exit with when clause must be directly in loop", N);
end if;
else
if Nkind (Parent (N)) /= N_If_Statement then
if Nkind (Parent (N)) = N_Elsif_Part then
Check_SPARK_Restriction
("exit must be in IF without ELSIF", N);
else
Check_SPARK_Restriction ("exit must be directly in IF", N);
end if;
elsif Nkind (Parent (Parent (N))) /= N_Loop_Statement then
Check_SPARK_Restriction
("exit must be in IF directly in loop", N);
-- First test the presence of ELSE, so that an exit in an ELSE leads
-- to an error mentioning the ELSE.
elsif Present (Else_Statements (Parent (N))) then
Check_SPARK_Restriction ("exit must be in IF without ELSE", N);
-- An exit in an ELSIF does not reach here, as it would have been
-- detected in the case (Nkind (Parent (N)) /= N_If_Statement).
elsif Present (Elsif_Parts (Parent (N))) then
Check_SPARK_Restriction ("exit must be in IF without ELSIF", N);
end if;
end if;
-- Chain exit statement to associated loop entity
Set_Next_Exit_Statement (N, First_Exit_Statement (Scope_Id));
Set_First_Exit_Statement (Scope_Id, N);
-- Since the exit may take us out of a loop, any previous assignment
-- statement is not useless, so clear last assignment indications. It
-- is OK to keep other current values, since if the exit statement
-- does not exit, then the current values are still valid.
Kill_Current_Values (Last_Assignment_Only => True);
end Analyze_Exit_Statement;
----------------------------
-- Analyze_Goto_Statement --
----------------------------
procedure Analyze_Goto_Statement (N : Node_Id) is
Label : constant Node_Id := Name (N);
Scope_Id : Entity_Id;
Label_Scope : Entity_Id;
Label_Ent : Entity_Id;
begin
Check_SPARK_Restriction ("goto statement is not allowed", N);
-- Actual semantic checks
Check_Unreachable_Code (N);
Kill_Current_Values (Last_Assignment_Only => True);
Analyze (Label);
Label_Ent := Entity (Label);
-- Ignore previous error
if Label_Ent = Any_Id then
Check_Error_Detected;
return;
-- 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;
-- 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;
-- 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_Return_Statement)
then
if Scope_Id /= Label_Scope then
Error_Msg_N
("cannot exit from program unit or accept statement", N);
end if;
return;
end if;
end loop;
raise Program_Error;
end Analyze_Goto_Statement;
--------------------------
-- Analyze_If_Statement --
--------------------------
-- 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 conditions). In
-- the analyzer, we ensure that code that will be deleted in this manner is
-- analyzed but not expanded. This is obviously more efficient, but more
-- significantly, difficulties arise if code is expanded and then
-- eliminated (e.g. exception table entries disappear). Similarly, itypes
-- generated in deleted code must be frozen from start, because the nodes
-- on which they depend will not be available at the freeze point.
procedure Analyze_If_Statement (N : Node_Id) is
E : Node_Id;
Save_Unblocked_Exit_Count : constant Nat := Unblocked_Exit_Count;
-- Recursively save value of this global, will be restored on exit
Save_In_Deleted_Code : Boolean;
Del : Boolean := False;
-- This flag gets set True if a True condition has been found, which
-- means that remaining ELSE/ELSIF parts are deleted.
procedure Analyze_Cond_Then (Cnode : Node_Id);
-- This is applied to either the N_If_Statement node itself or to an
-- N_Elsif_Part node. It deals with analyzing the condition and the THEN
-- statements associated with it.
-----------------------
-- Analyze_Cond_Then --
-----------------------
procedure Analyze_Cond_Then (Cnode : Node_Id) is
Cond : constant Node_Id := Condition (Cnode);
Tstm : constant List_Id := Then_Statements (Cnode);
begin
Unblocked_Exit_Count := Unblocked_Exit_Count + 1;
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
Set_Current_Value_Condition (Cnode);
-- If already deleting, then just analyze then statements
if Del then
Analyze_Statements (Tstm);
-- Compile time known value, not deleting yet
elsif Compile_Time_Known_Value (Cond) then
Save_In_Deleted_Code := In_Deleted_Code;
-- If condition is True, then analyze the THEN statements and set
-- no expansion for ELSE and ELSIF parts.
if Is_True (Expr_Value (Cond)) then
Analyze_Statements (Tstm);
Del := True;
Expander_Mode_Save_And_Set (False);
In_Deleted_Code := True;
-- If condition is False, analyze THEN with expansion off
else -- Is_False (Expr_Value (Cond))
Expander_Mode_Save_And_Set (False);
In_Deleted_Code := True;
Analyze_Statements (Tstm);
Expander_Mode_Restore;
In_Deleted_Code := Save_In_Deleted_Code;
end if;
-- Not known at compile time, not deleting, normal analysis
else
Analyze_Statements (Tstm);
end if;
end Analyze_Cond_Then;
-- Start of Analyze_If_Statement
begin
-- Initialize exit count for else statements. If there is no else part,
-- this count will stay non-zero reflecting the fact that the uncovered
-- else case is an unblocked exit.
Unblocked_Exit_Count := 1;
Analyze_Cond_Then (N);
-- Now to analyze the elsif parts if any are present
if Present (Elsif_Parts (N)) then
E := First (Elsif_Parts (N));
while Present (E) loop
Analyze_Cond_Then (E);
Next (E);
end loop;
end if;
if Present (Else_Statements (N)) then
Analyze_Statements (Else_Statements (N));
end if;
-- If all our exits were blocked by unconditional transfers of control,
-- then the entire IF statement acts as an unconditional transfer of
-- control, so treat it like one, and check unreachable code.
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;
if Del then
Expander_Mode_Restore;
In_Deleted_Code := Save_In_Deleted_Code;
end if;
if not Expander_Active
and then Compile_Time_Known_Value (Condition (N))
and then Serious_Errors_Detected = 0
then
if Is_True (Expr_Value (Condition (N))) then
Remove_Warning_Messages (Else_Statements (N));
if Present (Elsif_Parts (N)) then
E := First (Elsif_Parts (N));
while Present (E) loop
Remove_Warning_Messages (Then_Statements (E));
Next (E);
end loop;
end if;
else
Remove_Warning_Messages (Then_Statements (N));
end if;
end if;
end Analyze_If_Statement;
----------------------------------------
-- Analyze_Implicit_Label_Declaration --
----------------------------------------
-- An implicit label declaration is generated in the innermost enclosing
-- declarative part. This is done for labels, and block and loop names.
-- Note: any changes in this routine may need to be reflected in
-- Analyze_Label_Entity.
procedure Analyze_Implicit_Label_Declaration (N : Node_Id) is
Id : constant Node_Id := Defining_Identifier (N);
begin
Enter_Name (Id);
Set_Ekind (Id, E_Label);
Set_Etype (Id, Standard_Void_Type);
Set_Enclosing_Scope (Id, Current_Scope);
end Analyze_Implicit_Label_Declaration;
------------------------------
-- Analyze_Iteration_Scheme --
------------------------------
procedure Analyze_Iteration_Scheme (N : Node_Id) is
Cond : Node_Id;
Iter_Spec : Node_Id;
Loop_Spec : Node_Id;
begin
-- For an infinite loop, there is no iteration scheme
if No (N) then
return;
end if;
Cond := Condition (N);
Iter_Spec := Iterator_Specification (N);
Loop_Spec := Loop_Parameter_Specification (N);
if Present (Cond) then
Analyze_And_Resolve (Cond, Any_Boolean);
Check_Unset_Reference (Cond);
Set_Current_Value_Condition (N);
elsif Present (Iter_Spec) then
Analyze_Iterator_Specification (Iter_Spec);
else
Analyze_Loop_Parameter_Specification (Loop_Spec);
end if;
end Analyze_Iteration_Scheme;
------------------------------------
-- Analyze_Iterator_Specification --
------------------------------------
procedure Analyze_Iterator_Specification (N : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
Def_Id : constant Node_Id := Defining_Identifier (N);
Subt : constant Node_Id := Subtype_Indication (N);
Iter_Name : constant Node_Id := Name (N);
Ent : Entity_Id;
Typ : Entity_Id;
begin
Enter_Name (Def_Id);
if Present (Subt) then
Analyze (Subt);
end if;
Preanalyze_Range (Iter_Name);
-- Set the kind of the loop variable, which is not visible within
-- the iterator name.
Set_Ekind (Def_Id, E_Variable);
-- If the domain of iteration is an expression, create a declaration for
-- it, so that finalization actions are introduced outside of the loop.
-- The declaration must be a renaming because the body of the loop may
-- assign to elements.
if not Is_Entity_Name (Iter_Name)
-- When the context is a quantified expression, the renaming
-- declaration is delayed until the expansion phase if we are
-- doing expansion.
and then (Nkind (Parent (N)) /= N_Quantified_Expression
or else Operating_Mode = Check_Semantics)
-- Do not perform this expansion in Alfa mode, since the formal
-- verification directly deals with the source form of the iterator.
and then not Alfa_Mode
then
declare
Id : constant Entity_Id := Make_Temporary (Loc, 'R', Iter_Name);
Decl : Node_Id;
begin
Typ := Etype (Iter_Name);
-- Protect against malformed iterator
if Typ = Any_Type then
Error_Msg_N ("invalid expression in loop iterator", Iter_Name);
return;
end if;
-- The name in the renaming declaration may be a function call.
-- Indicate that it does not come from source, to suppress
-- spurious warnings on renamings of parameterless functions,
-- a common enough idiom in user-defined iterators.
Decl :=
Make_Object_Renaming_Declaration (Loc,
Defining_Identifier => Id,
Subtype_Mark => New_Occurrence_Of (Typ, Loc),
Name =>
New_Copy_Tree (Iter_Name, New_Sloc => Loc));
Insert_Actions (Parent (Parent (N)), New_List (Decl));
Rewrite (Name (N), New_Occurrence_Of (Id, Loc));
Set_Etype (Id, Typ);
Set_Etype (Name (N), Typ);
end;
-- Container is an entity or an array with uncontrolled components, or
-- else it is a container iterator given by a function call, typically
-- called Iterate in the case of predefined containers, even though
-- Iterate is not a reserved name. What matters is that the return type
-- of the function is an iterator type.
elsif Is_Entity_Name (Iter_Name) then
Analyze (Iter_Name);
if Nkind (Iter_Name) = N_Function_Call then
declare
C : constant Node_Id := Name (Iter_Name);
I : Interp_Index;
It : Interp;
begin
if not Is_Overloaded (Iter_Name) then
Resolve (Iter_Name, Etype (C));
else
Get_First_Interp (C, I, It);
while It.Typ /= Empty loop
if Reverse_Present (N) then
if Is_Reversible_Iterator (It.Typ) then
Resolve (Iter_Name, It.Typ);
exit;
end if;
elsif Is_Iterator (It.Typ) then
Resolve (Iter_Name, It.Typ);
exit;
end if;
Get_Next_Interp (I, It);
end loop;
end if;
end;
-- Domain of iteration is not overloaded
else
Resolve (Iter_Name, Etype (Iter_Name));
end if;
end if;
Typ := Etype (Iter_Name);
if Is_Array_Type (Typ) then
if Of_Present (N) then
Set_Etype (Def_Id, Component_Type (Typ));
-- Here we have a missing Range attribute
else
Error_Msg_N
("missing Range attribute in iteration over an array", N);
-- In Ada 2012 mode, this may be an attempt at an iterator
if Ada_Version >= Ada_2012 then
Error_Msg_NE
("\if& is meant to designate an element of the array, use OF",
N, Def_Id);
end if;
-- Prevent cascaded errors
Set_Ekind (Def_Id, E_Loop_Parameter);
Set_Etype (Def_Id, Etype (First_Index (Typ)));
end if;
-- Check for type error in iterator
elsif Typ = Any_Type then
return;
-- Iteration over a container
else
Set_Ekind (Def_Id, E_Loop_Parameter);
if Of_Present (N) then
-- The type of the loop variable is the Iterator_Element aspect of
-- the container type.
declare
Element : constant Entity_Id :=
Find_Aspect (Typ, Aspect_Iterator_Element);
begin
if No (Element) then
Error_Msg_NE ("cannot iterate over&", N, Typ);
return;
else
Set_Etype (Def_Id, Entity (Element));
-- If the container has a variable indexing aspect, the
-- element is a variable and is modifiable in the loop.
if Present (Find_Aspect (Typ, Aspect_Variable_Indexing)) then
Set_Ekind (Def_Id, E_Variable);
end if;
end if;
end;
else
-- For an iteration of the form IN, the name must denote an
-- iterator, typically the result of a call to Iterate. Give a
-- useful error message when the name is a container by itself.
if Is_Entity_Name (Original_Node (Name (N)))
and then not Is_Iterator (Typ)
then
if No (Find_Aspect (Typ, Aspect_Iterator_Element)) then
Error_Msg_NE
("cannot iterate over&", Name (N), Typ);
else
Error_Msg_N
("name must be an iterator, not a container", Name (N));
end if;
Error_Msg_NE
("\to iterate directly over the elements of a container, " &
"write `of &`", Name (N), Original_Node (Name (N)));
end if;
-- The result type of Iterate function is the classwide type of
-- the interface parent. We need the specific Cursor type defined
-- in the container package.
Ent := First_Entity (Scope (Typ));
while Present (Ent) loop
if Chars (Ent) = Name_Cursor then
Set_Etype (Def_Id, Etype (Ent));
exit;
end if;
Next_Entity (Ent);
end loop;
end if;
end if;
end Analyze_Iterator_Specification;
-------------------
-- Analyze_Label --
-------------------
-- Note: the semantic work required for analyzing labels (setting them as
-- reachable) was done in a prepass through the statements in the block,
-- so that forward gotos would be properly handled. See Analyze_Statements
-- for further details. The only processing required here is to deal with
-- optimizations that depend on an assumption of sequential control flow,
-- since of course the occurrence of a label breaks this assumption.
procedure Analyze_Label (N : Node_Id) is
pragma Warnings (Off, N);
begin
Kill_Current_Values;
end Analyze_Label;
--------------------------
-- Analyze_Label_Entity --
--------------------------
procedure Analyze_Label_Entity (E : Entity_Id) is
begin
Set_Ekind (E, E_Label);
Set_Etype (E, Standard_Void_Type);
Set_Enclosing_Scope (E, Current_Scope);
Set_Reachable (E, True);
end Analyze_Label_Entity;
------------------------------------------
-- Analyze_Loop_Parameter_Specification --
------------------------------------------
procedure Analyze_Loop_Parameter_Specification (N : Node_Id) is
Loop_Nod : constant Node_Id := Parent (Parent (N));
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.
function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean;
-- N is the node for an arbitrary construct. This function searches the
-- construct N to see if any expressions within it contain function
-- calls that use the secondary stack, returning True if any such call
-- is found, and False otherwise.
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.
--------------------------------------
-- Check_Controlled_Array_Attribute --
--------------------------------------
procedure Check_Controlled_Array_Attribute (DS : Node_Id) is
begin
if Nkind (DS) = N_Attribute_Reference
and then Is_Entity_Name (Prefix (DS))
and then Ekind (Entity (Prefix (DS))) = E_Function
and then Is_Array_Type (Etype (Entity (Prefix (DS))))
and then
Is_Controlled (Component_Type (Etype (Entity (Prefix (DS)))))
and then Expander_Active
then
declare
Loc : constant Source_Ptr := Sloc (N);
Arr : constant Entity_Id := Etype (Entity (Prefix (DS)));
Indx : constant Entity_Id :=
Base_Type (Etype (First_Index (Arr)));
Subt : constant Entity_Id := Make_Temporary (Loc, 'S');
Decl : Node_Id;
begin
Decl :=
Make_Subtype_Declaration (Loc,
Defining_Identifier => Subt,
Subtype_Indication =>
Make_Subtype_Indication (Loc,
Subtype_Mark => New_Reference_To (Indx, Loc),
Constraint =>
Make_Range_Constraint (Loc, Relocate_Node (DS))));
Insert_Before (Loop_Nod, Decl);
Analyze (Decl);
Rewrite (DS,
Make_Attribute_Reference (Loc,
Prefix => New_Reference_To (Subt, Loc),
Attribute_Name => Attribute_Name (DS)));
Analyze (DS);
end;
end if;
end Check_Controlled_Array_Attribute;
------------------------------------
-- Has_Call_Using_Secondary_Stack --
------------------------------------
function Has_Call_Using_Secondary_Stack (N : Node_Id) return Boolean is
function Check_Call (N : Node_Id) return Traverse_Result;
-- Check if N is a function call which uses the secondary stack
----------------
-- Check_Call --
----------------
function Check_Call (N : Node_Id) return Traverse_Result is
Nam : Node_Id;
Subp : Entity_Id;
Return_Typ : Entity_Id;
begin
if Nkind (N) = N_Function_Call then
Nam := Name (N);
-- Call using access to subprogram with explicit dereference
if Nkind (Nam) = N_Explicit_Dereference then
Subp := Etype (Nam);
-- Call using a selected component notation or Ada 2005 object
-- operation notation
elsif Nkind (Nam) = N_Selected_Component then
Subp := Entity (Selector_Name (Nam));
-- Common case
else
Subp := Entity (Nam);
end if;
Return_Typ := Etype (Subp);
if Is_Composite_Type (Return_Typ)
and then not Is_Constrained (Return_Typ)
then
return Abandon;
elsif Sec_Stack_Needed_For_Return (Subp) then
return Abandon;
end if;
end if;
-- Continue traversing the tree
return OK;
end Check_Call;
function Check_Calls is new Traverse_Func (Check_Call);
-- Start of processing for Has_Call_Using_Secondary_Stack
begin
return Check_Calls (N) = Abandon;
end Has_Call_Using_Secondary_Stack;
--------------------
-- Process_Bounds --
--------------------
procedure Process_Bounds (R : Node_Id) is
Loc : constant Source_Ptr := Sloc (N);
function One_Bound
(Original_Bound : Node_Id;
Analyzed_Bound : Node_Id;
Typ : Entity_Id) return Node_Id;
-- Capture value of bound and return captured value
---------------
-- One_Bound --
---------------
function One_Bound
(Original_Bound : Node_Id;
Analyzed_Bound : Node_Id;
Typ : Entity_Id) return Node_Id
is
Assign : Node_Id;
Decl : Node_Id;
Id : Entity_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_In (Analyzed_Bound, N_Integer_Literal,
N_Character_Literal)
or else Is_Entity_Name (Analyzed_Bound)
then
Analyze_And_Resolve (Original_Bound, Typ);
return Original_Bound;
end if;
-- Normally, the best approach is simply to generate a constant
-- declaration that captures the bound. However, there is a nasty
-- case where this is wrong. If the bound is complex, and has a
-- possible use of the secondary stack, we need to generate a
-- separate assignment statement to ensure the creation of a block
-- which will release the secondary stack.
-- We prefer the constant declaration, since it leaves us with a
-- proper trace of the value, useful in optimizations that get rid
-- of junk range checks.
if not Has_Call_Using_Secondary_Stack (Analyzed_Bound) then
Analyze_And_Resolve (Original_Bound, Typ);
Force_Evaluation (Original_Bound);
return Original_Bound;
end if;
Id := Make_Temporary (Loc, 'R', Original_Bound);
-- Here we make a declaration with a separate assignment
-- statement, and insert before loop header.
Decl :=
Make_Object_Declaration (Loc,
Defining_Identifier => Id,
Object_Definition => New_Occurrence_Of (Typ, Loc));
Assign :=
Make_Assignment_Statement (Loc,
Name => New_Occurrence_Of (Id, Loc),
Expression => Relocate_Node (Original_Bound));
Insert_Actions (Loop_Nod, New_List (Decl, Assign));
-- Now that this temporary variable is initialized we decorate it
-- as safe-to-reevaluate to inform to the backend that no further
-- asignment will be issued and hence it can be handled as side
-- effect free. Note that this decoration must be done when the
-- assignment has been analyzed because otherwise it will be
-- rejected (see Analyze_Assignment).
Set_Is_Safe_To_Reevaluate (Id);
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;
Hi : constant Node_Id := High_Bound (R);
Lo : constant Node_Id := Low_Bound (R);
R_Copy : constant Node_Id := New_Copy_Tree (R);
New_Hi : Node_Id;
New_Lo : Node_Id;
Typ : Entity_Id;
-- Start of processing for Process_Bounds
begin
Set_Parent (R_Copy, Parent (R));
Preanalyze_Range (R_Copy);
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 with 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 := One_Bound (Lo, Low_Bound (R_Copy), Typ);
New_Hi := One_Bound (Hi, High_Bound (R_Copy), Typ);
-- Propagate staticness to loop range itself, in case the
-- corresponding subtype is static.
if New_Lo /= Lo
and then Is_Static_Expression (New_Lo)
then
Rewrite (Low_Bound (R), New_Copy (New_Lo));
end if;
if New_Hi /= Hi
and then Is_Static_Expression (New_Hi)
then
Rewrite (High_Bound (R), New_Copy (New_Hi));
end if;
end Process_Bounds;
-- Local variables
DS : constant Node_Id := Discrete_Subtype_Definition (N);
Id : constant Entity_Id := Defining_Identifier (N);
DS_Copy : Node_Id;
-- Start of processing for Analyze_Loop_Parameter_Specification
begin
Enter_Name (Id);
-- We always consider the loop variable to be referenced, since the loop
-- may be used just for counting purposes.
Generate_Reference (Id, N, ' ');
-- Check for the case of loop variable hiding a local variable (used
-- later on to give a nice warning if the hidden variable is never
-- assigned).
declare
H : constant Entity_Id := Homonym (Id);
begin
if Present (H)
and then Ekind (H) = E_Variable
and then Is_Discrete_Type (Etype (H))
and then Enclosing_Dynamic_Scope (H) = Enclosing_Dynamic_Scope (Id)
then
Set_Hiding_Loop_Variable (H, Id);
end if;
end;
-- Loop parameter specification must include subtype mark in SPARK
if Nkind (DS) = N_Range then
Check_SPARK_Restriction
("loop parameter specification must include subtype mark", N);
end if;
-- Analyze the subtype definition and create temporaries for the bounds.
-- Do not evaluate the range when preanalyzing a quantified expression
-- because bounds expressed as function calls with side effects will be
-- erroneously replicated.
if Nkind (DS) = N_Range
and then Expander_Active
and then Nkind (Parent (N)) /= N_Quantified_Expression
then
Process_Bounds (DS);
-- Either the expander not active or the range of iteration is a subtype
-- indication, an entity, or a function call that yields an aggregate or
-- a container.
else
DS_Copy := New_Copy_Tree (DS);
Set_Parent (DS_Copy, Parent (DS));
Preanalyze_Range (DS_Copy);
-- Ada 2012: If the domain of iteration is a function call, it is the
-- new iterator form.
if Nkind (DS_Copy) = N_Function_Call
or else
(Is_Entity_Name (DS_Copy)
and then not Is_Type (Entity (DS_Copy)))
then
-- This is an iterator specification. Rewrite it as such and
-- analyze it to capture function calls that may require
-- finalization actions.
declare
I_Spec : constant Node_Id :=
Make_Iterator_Specification (Sloc (N),
Defining_Identifier => Relocate_Node (Id),
Name => DS_Copy,
Subtype_Indication => Empty,
Reverse_Present => Reverse_Present (N));
Scheme : constant Node_Id := Parent (N);
begin
Set_Iterator_Specification (Scheme, I_Spec);
Set_Loop_Parameter_Specification (Scheme, Empty);
Analyze_Iterator_Specification (I_Spec);
-- In a generic context, analyze the original domain of
-- iteration, for name capture.
if not Expander_Active then
Analyze (DS);
end if;
-- Set kind of loop parameter, which may be used in the
-- subsequent analysis of the condition in a quantified
-- expression.
Set_Ekind (Id, E_Loop_Parameter);
return;
end;
-- Domain of iteration is not a function call, and is side-effect
-- free.
else
-- A quantified expression that appears in a pre/post condition
-- is pre-analyzed several times. If the range is given by an
-- attribute reference it is rewritten as a range, and this is
-- done even with expansion disabled. If the type is already set
-- do not reanalyze, because a range with static bounds may be
-- typed Integer by default.
if Nkind (Parent (N)) = N_Quantified_Expression
and then Present (Etype (DS))
then
null;
else
Analyze (DS);
end if;
end if;
end if;
if DS = Error then
return;
end if;
-- Some additional checks if we are iterating through a type
if Is_Entity_Name (DS)
and then Present (Entity (DS))
and then Is_Type (Entity (DS))
then
-- The subtype indication may denote the completion of an incomplete
-- type declaration.
if Ekind (Entity (DS)) = E_Incomplete_Type then
Set_Entity (DS, Get_Full_View (Entity (DS)));
Set_Etype (DS, Entity (DS));
end if;
-- Attempt to iterate through non-static predicate
if Is_Discrete_Type (Entity (DS))
and then Present (Predicate_Function (Entity (DS)))
and then No (Static_Predicate (Entity (DS)))
then
Bad_Predicated_Subtype_Use
("cannot use subtype& with non-static predicate for loop " &
"iteration", DS, Entity (DS));
end if;
end if;
-- Error if not discrete type
if not Is_Discrete_Type (Etype (DS)) then
Wrong_Type (DS, Any_Discrete);
Set_Etype (DS, Any_Type);
end if;
Check_Controlled_Array_Attribute (DS);
Make_Index (DS, N, In_Iter_Schm => True);
Set_Ekind (Id, E_Loop_Parameter);
-- A quantified expression which appears in a pre- or post-condition may
-- be analyzed multiple times. The analysis of the range creates several
-- itypes which reside in different scopes depending on whether the pre-
-- or post-condition has been expanded. Update the type of the loop
-- variable to reflect the proper itype at each stage of analysis.
if No (Etype (Id))
or else Etype (Id) = Any_Type
or else
(Present (Etype (Id))
and then Is_Itype (Etype (Id))
and then Nkind (Parent (Loop_Nod)) = N_Expression_With_Actions
and then Nkind (Original_Node (Parent (Loop_Nod))) =
N_Quantified_Expression)
then
Set_Etype (Id, Etype (DS));
end if;
-- Treat a range as an implicit reference to the type, to inhibit
-- spurious warnings.
Generate_Reference (Base_Type (Etype (DS)), N, ' ');
Set_Is_Known_Valid (Id, True);
-- The loop is not a declarative part, so the loop variable must be
-- frozen explicitly. Do not freeze while preanalyzing a quantified
-- expression because the freeze node will not be inserted into the
-- tree due to flag Is_Spec_Expression being set.
if Nkind (Parent (N)) /= N_Quantified_Expression then
declare
Flist : constant List_Id := Freeze_Entity (Id, N);
begin
if Is_Non_Empty_List (Flist) then
Insert_Actions (N, Flist);
end if;
end;
end if;
-- Check for null or possibly null range and issue warning. We suppress
-- such messages in generic templates and instances, because in practice
-- they tend to be dubious in these cases.
if Nkind (DS) = N_Range and then Comes_From_Source (N) then
declare
L : constant Node_Id := Low_Bound (DS);
H : constant Node_Id := High_Bound (DS);
begin
-- If range of loop is null, issue warning
if Compile_Time_Compare (L, H, Assume_Valid => True) = GT then
-- Suppress the warning if inside a generic template or
-- instance, since in practice they tend to be dubious in these
-- cases since they can result from intended parametrization.
if not Inside_A_Generic
and then not In_Instance
then
-- Specialize msg if invalid values could make the loop
-- non-null after all.
if Compile_Time_Compare
(L, H, Assume_Valid => False) = GT
then
Error_Msg_N
("??loop range is null, loop will not execute", DS);
-- Since we know the range of the loop is null, set the
-- appropriate flag to remove the loop entirely during
-- expansion.
Set_Is_Null_Loop (Loop_Nod);
-- Here is where the loop could execute because of invalid
-- values, so issue appropriate message and in this case we
-- do not set the Is_Null_Loop flag since the loop may
-- execute.
else
Error_Msg_N
("??loop range may be null, loop may not execute",
DS);
Error_Msg_N
("??can only execute if invalid values are present",
DS);
end if;
end if;
-- In either case, suppress warnings in the body of the loop,
-- since it is likely that these warnings will be inappropriate
-- if the loop never actually executes, which is likely.
Set_Suppress_Loop_Warnings (Loop_Nod);
-- The other case for a warning is a reverse loop where the
-- upper bound is the integer literal zero or one, and the
-- lower bound can be positive.
-- For example, we have
-- for J in reverse N .. 1 loop
-- In practice, this is very likely to be a case of reversing
-- the bounds incorrectly in the range.
elsif Reverse_Present (N)
and then Nkind (Original_Node (H)) = N_Integer_Literal
and then
(Intval (Original_Node (H)) = Uint_0
or else Intval (Original_Node (H)) = Uint_1)
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;
end Analyze_Loop_Parameter_Specification;
----------------------------
-- Analyze_Loop_Statement --
----------------------------
procedure Analyze_Loop_Statement (N : Node_Id) is
function Is_Container_Iterator (Iter : Node_Id) return Boolean;
-- Given a loop iteration scheme, determine whether it is an Ada 2012
-- container iteration.
function Is_Wrapped_In_Block (N : Node_Id) return Boolean;
-- Determine whether node N is the sole statement of a block
---------------------------
-- Is_Container_Iterator --
---------------------------
function Is_Container_Iterator (Iter : Node_Id) return Boolean is
begin
-- Infinite loop
if No (Iter) then
return False;
-- While loop
elsif Present (Condition (Iter)) then
return False;
-- for Def_Id in [reverse] Name loop
-- for Def_Id [: Subtype_Indication] of [reverse] Name loop
elsif Present (Iterator_Specification (Iter)) then
declare
Nam : constant Node_Id := Name (Iterator_Specification (Iter));
Nam_Copy : Node_Id;
begin
Nam_Copy := New_Copy_Tree (Nam);
Set_Parent (Nam_Copy, Parent (Nam));
Preanalyze_Range (Nam_Copy);
-- The only two options here are iteration over a container or
-- an array.
return not Is_Array_Type (Etype (Nam_Copy));
end;
-- for Def_Id in [reverse] Discrete_Subtype_Definition loop
else
declare
LP : constant Node_Id := Loop_Parameter_Specification (Iter);
DS : constant Node_Id := Discrete_Subtype_Definition (LP);
DS_Copy : Node_Id;
begin
DS_Copy := New_Copy_Tree (DS);
Set_Parent (DS_Copy, Parent (DS));
Preanalyze_Range (DS_Copy);
-- Check for a call to Iterate ()
return
Nkind (DS_Copy) = N_Function_Call
and then Needs_Finalization (Etype (DS_Copy));
end;
end if;
end Is_Container_Iterator;
-------------------------
-- Is_Wrapped_In_Block --
-------------------------
function Is_Wrapped_In_Block (N : Node_Id) return Boolean is
HSS : constant Node_Id := Parent (N);
begin
return
Nkind (HSS) = N_Handled_Sequence_Of_Statements
and then Nkind (Parent (HSS)) = N_Block_Statement
and then First (Statements (HSS)) = N
and then No (Next (First (Statements (HSS))));
end Is_Wrapped_In_Block;
-- Local declarations
Id : constant Node_Id := Identifier (N);
Iter : constant Node_Id := Iteration_Scheme (N);
Loc : constant Source_Ptr := Sloc (N);
Ent : Entity_Id;
-- Start of processing for Analyze_Loop_Statement
begin
if Present (Id) then
-- Make name visible, e.g. for use in exit statements. Loop labels
-- are always considered to be referenced.
Analyze (Id);
Ent := Entity (Id);
-- Guard against serious error (typically, a scope mismatch when
-- semantic analysis is requested) by creating loop entity to
-- continue analysis.
if No (Ent) then
if Total_Errors_Detected /= 0 then
Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
else
raise Program_Error;
end if;
else
Generate_Reference (Ent, N, ' ');
Generate_Definition (Ent);
-- If we found a label, mark its type. If not, ignore it, since it
-- means we have a conflicting declaration, which would already
-- have been diagnosed at declaration time. Set Label_Construct
-- of the implicit label declaration, which is not created by the
-- parser for generic units.
if Ekind (Ent) = E_Label then
Set_Ekind (Ent, E_Loop);
if Nkind (Parent (Ent)) = N_Implicit_Label_Declaration then
Set_Label_Construct (Parent (Ent), N);
end if;
end if;
end if;
-- Case of no identifier present
else
Ent := New_Internal_Entity (E_Loop, Current_Scope, Loc, 'L');
Set_Etype (Ent, Standard_Void_Type);
Set_Parent (Ent, N);
end if;
-- Iteration over a container in Ada 2012 involves the creation of a
-- controlled iterator object. Wrap the loop in a block to ensure the
-- timely finalization of the iterator and release of container locks.
if Ada_Version >= Ada_2012
and then Is_Container_Iterator (Iter)
and then not Is_Wrapped_In_Block (N)
then
Rewrite (N,
Make_Block_Statement (Loc,
Declarations => New_List,
Handled_Statement_Sequence =>
Make_Handled_Sequence_Of_Statements (Loc,
Statements => New_List (Relocate_Node (N)))));
Analyze (N);
return;
end if;
-- Kill current values on entry to loop, since statements in the body of
-- the loop may have been executed before the loop is entered. Similarly
-- we kill values after the loop, since we do not know that the body of
-- the loop was executed.
Kill_Current_Values;
Push_Scope (Ent);
Analyze_Iteration_Scheme (Iter);
-- Check for following case which merits a warning if the type E of is
-- a multi-dimensional array (and no explicit subscript ranges present).
-- for J in E'Range
-- for K in E'Range
if Present (Iter)
and then Present (Loop_Parameter_Specification (Iter))
then
declare
LPS : constant Node_Id := Loop_Parameter_Specification (Iter);
DSD : constant Node_Id :=
Original_Node (Discrete_Subtype_Definition (LPS));
begin
if Nkind (DSD) = N_Attribute_Reference
and then Attribute_Name (DSD) = Name_Range
and then No (Expressions (DSD))
then
declare
Typ : constant Entity_Id := Etype (Prefix (DSD));
begin
if Is_Array_Type (Typ)
and then Number_Dimensions (Typ) > 1
and then Nkind (Parent (N)) = N_Loop_Statement
and then Present (Iteration_Scheme (Parent (N)))
then
declare
OIter : constant Node_Id :=
Iteration_Scheme (Parent (N));
OLPS : constant Node_Id :=
Loop_Parameter_Specification (OIter);
ODSD : constant Node_Id :=
Original_Node (Discrete_Subtype_Definition (OLPS));
begin
if Nkind (ODSD) = N_Attribute_Reference
and then Attribute_Name (ODSD) = Name_Range
and then No (Expressions (ODSD))
and then Etype (Prefix (ODSD)) = Typ
then
Error_Msg_Sloc := Sloc (ODSD);
Error_Msg_N
("inner range same as outer range#??", DSD);
end if;
end;
end if;
end;
end if;
end;
end if;
-- Analyze the statements of the body except in the case of an Ada 2012
-- iterator with the expander active. In this case the expander will do
-- a rewrite of the loop into a while loop. We will then analyze the
-- loop body when we analyze this while loop.
-- We need to do this delay because if the container is for indefinite
-- types the actual subtype of the components will only be determined
-- when the cursor declaration is analyzed.
-- If the expander is not active, or in Alfa mode, then we want to
-- analyze the loop body now even in the Ada 2012 iterator case, since
-- the rewriting will not be done. Insert the loop variable in the
-- current scope, if not done when analysing the iteration scheme.
if No (Iter)
or else No (Iterator_Specification (Iter))
or else not Full_Expander_Active
then
if Present (Iter)
and then Present (Iterator_Specification (Iter))
then
declare
Id : constant Entity_Id :=
Defining_Identifier (Iterator_Specification (Iter));
begin
if Scope (Id) /= Current_Scope then
Enter_Name (Id);
end if;
end;
end if;
Analyze_Statements (Statements (N));
end if;
-- Finish up processing for the loop. We kill all current values, since
-- in general we don't know if the statements in the loop have been
-- executed. We could do a bit better than this with a loop that we
-- know will execute at least once, but it's not worth the trouble and
-- the front end is not in the business of flow tracing.
Process_End_Label (N, 'e', Ent);
End_Scope;
Kill_Current_Values;
-- Check for infinite loop. Skip check for generated code, since it
-- justs waste time and makes debugging the routine called harder.
-- Note that we have to wait till the body of the loop is fully analyzed
-- before making this call, since Check_Infinite_Loop_Warning relies on
-- being able to use semantic visibility information to find references.
if Comes_From_Source (N) then
Check_Infinite_Loop_Warning (N);
end if;
-- Code after loop is unreachable if the loop has no WHILE or FOR and
-- contains no EXIT statements within the body of the loop.
if No (Iter) and then not Has_Exit (Ent) then
Check_Unreachable_Code (N);
end if;
end Analyze_Loop_Statement;
----------------------------
-- Analyze_Null_Statement --
----------------------------
-- Note: the semantics of the null statement is implemented by a single
-- null statement, too bad everything isn't as simple as this!
procedure Analyze_Null_Statement (N : Node_Id) is
pragma Warnings (Off, N);
begin
null;
end Analyze_Null_Statement;
------------------------
-- Analyze_Statements --
------------------------
procedure Analyze_Statements (L : List_Id) is
S : Node_Id;
Lab : Entity_Id;
begin
-- The labels declared in the statement list are reachable from
-- statements in the list. We do this as a prepass so that any goto
-- statement will be properly flagged if its target is not reachable.
-- This is not required, but is nice behavior!
S := First (L);
while Present (S) loop
if Nkind (S) = N_Label then
Analyze (Identifier (S));
Lab := Entity (Identifier (S));
-- If we found a label mark it as reachable
if Ekind (Lab) = E_Label then
Generate_Definition (Lab);
Set_Reachable (Lab);
if Nkind (Parent (Lab)) = N_Implicit_Label_Declaration then
Set_Label_Construct (Parent (Lab), S);
end if;
-- If we failed to find a label, it means the implicit declaration
-- of the label was hidden. A for-loop parameter can do this to
-- a label with the same name inside the loop, since the implicit
-- label declaration is in the innermost enclosing body or block
-- statement.
else
Error_Msg_Sloc := Sloc (Lab);
Error_Msg_N
("implicit label declaration for & is hidden#",
Identifier (S));
end if;
end if;
Next (S);
end loop;
-- Perform semantic analysis on all statements
Conditional_Statements_Begin;
S := First (L);
while Present (S) loop
Analyze (S);
-- Remove dimension in all statements
Remove_Dimension_In_Statement (S);
Next (S);
end loop;
Conditional_Statements_End;
-- Make labels unreachable. Visibility is not sufficient, because labels
-- in one if-branch for example are not reachable from the other branch,
-- even though their declarations are in the enclosing declarative part.
S := First (L);
while Present (S) loop
if Nkind (S) = N_Label then
Set_Reachable (Entity (Identifier (S)), False);
end if;
Next (S);
end loop;
end Analyze_Statements;
----------------------------
-- Check_Unreachable_Code --
----------------------------
procedure Check_Unreachable_Code (N : Node_Id) is
Error_Node : Node_Id;
P : Node_Id;
begin
if Is_List_Member (N)
and then Comes_From_Source (N)
then
declare
Nxt : Node_Id;
begin
Nxt := Original_Node (Next (N));
-- Skip past pragmas
while Nkind (Nxt) = N_Pragma loop
Nxt := Original_Node (Next (Nxt));
end loop;
-- If a label follows us, then we never have dead code, since
-- someone could branch to the label, so we just ignore it, unless
-- we are in formal mode where goto statements are not allowed.
if Nkind (Nxt) = N_Label
and then not Restriction_Check_Required (SPARK)
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
-- Special very annoying exception. If we have a return that
-- follows a raise, then we allow it without a warning, since
-- the Ada RM annoyingly requires a useless return here!
if Nkind (Original_Node (N)) /= N_Raise_Statement
or else Nkind (Nxt) /= N_Simple_Return_Statement
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.
Error_Node := Nxt;
-- If we have unreachable code, analyze and remove the
-- unreachable code, since it is useless and we don't
-- want to generate junk warnings.
-- We skip this step if we are not in code generation mode.
-- This is the one case where we remove dead code in the
-- semantics as opposed to the expander, and we do not want
-- to remove code if we are not in code generation mode,
-- since this messes up the ASIS trees.
-- Note that one might react by moving the whole circuit to
-- exp_ch5, but then we lose the warning in -gnatc mode.
if Operating_Mode = Generate_Code then
loop
Nxt := Next (N);
-- Quit deleting when we have nothing more to delete
-- or if we hit a label (since someone could transfer
-- control to a label, so we should not delete it).
exit when No (Nxt) or else Nkind (Nxt) = N_Label;
-- Statement/declaration is to be deleted
Analyze (Nxt);
Remove (Nxt);
Kill_Dead_Code (Nxt);
end loop;
end if;
-- Now issue the warning (or error in formal mode)
if Restriction_Check_Required (SPARK) then
Check_SPARK_Restriction
("unreachable code is not allowed", Error_Node);
else
Error_Msg ("??unreachable code!", Sloc (Error_Node));
end if;
end if;
-- If the unconditional transfer of control instruction is the
-- last statement of a sequence, then see if our parent 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;
end if;
end Check_Unreachable_Code;
----------------------
-- Preanalyze_Range --
----------------------
procedure Preanalyze_Range (R_Copy : Node_Id) is
Save_Analysis : constant Boolean := Full_Analysis;
Typ : Entity_Id;
begin
Full_Analysis := False;
Expander_Mode_Save_And_Set (False);
Analyze (R_Copy);
if Nkind (R_Copy) in N_Subexpr
and then 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;
-- Subtype mark in iteration scheme
if Is_Entity_Name (R_Copy)
and then Is_Type (Entity (R_Copy))
then
null;
-- Expression in range, or Ada 2012 iterator
elsif Nkind (R_Copy) in N_Subexpr then
Resolve (R_Copy);
Typ := Etype (R_Copy);
if Is_Discrete_Type (Typ) then
null;
-- Check that the resulting object is an iterable container
elsif Present (Find_Aspect (Typ, Aspect_Iterator_Element))
or else Present (Find_Aspect (Typ, Aspect_Constant_Indexing))
or else Present (Find_Aspect (Typ, Aspect_Variable_Indexing))
then
null;
-- The expression may yield an implicit reference to an iterable
-- container. Insert explicit dereference so that proper type is
-- visible in the loop.
elsif Has_Implicit_Dereference (Etype (R_Copy)) then
declare
Disc : Entity_Id;
begin
Disc := First_Discriminant (Typ);
while Present (Disc) loop
if Has_Implicit_Dereference (Disc) then
Build_Explicit_Dereference (R_Copy, Disc);
exit;
end if;
Next_Discriminant (Disc);
end loop;
end;
end if;
end if;
Expander_Mode_Restore;
Full_Analysis := Save_Analysis;
end Preanalyze_Range;
end Sem_Ch5;