2009-06-12 Bill Holmes <billholmes54@gmail.com>

[mono.git] / mcs / mcs / expression.cs

//
// expression.cs: Expression representation for the IL tree.
//
// Author:
//   Miguel de Icaza (miguel@ximian.com)
//   Marek Safar (marek.safar@gmail.com)
//
// Copyright 2001, 2002, 2003 Ximian, Inc.
// Copyright 2003-2008 Novell, Inc.
//
#define USE_OLD

namespace Mono.CSharp {
        using System;
        using System.Collections;
        using System.Reflection;
        using System.Reflection.Emit;
        using System.Text;

        //
        // This is an user operator expression, automatically created during
        // resolve phase
        //
        public class UserOperatorCall : Expression {
                public delegate Expression ExpressionTreeExpression (EmitContext ec, MethodGroupExpr mg);

                protected readonly ArrayList arguments;
                protected readonly MethodGroupExpr mg;
                readonly ExpressionTreeExpression expr_tree;

                public UserOperatorCall (MethodGroupExpr mg, ArrayList args, ExpressionTreeExpression expr_tree, Location loc)
                {
                        this.mg = mg;
                        this.arguments = args;
                        this.expr_tree = expr_tree;

                        type = TypeManager.TypeToCoreType (((MethodInfo) mg).ReturnType);
                        eclass = ExprClass.Value;
                        this.loc = loc;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        if (expr_tree != null)
                                return expr_tree (ec, mg);

                        ArrayList args = new ArrayList (arguments.Count + 1);
                        args.Add (new Argument (new NullLiteral (loc)));
                        args.Add (new Argument (mg.CreateExpressionTree (ec)));
                        foreach (Argument a in arguments) {
                                args.Add (new Argument (a.Expr.CreateExpressionTree (ec)));
                        }

                        return CreateExpressionFactoryCall ("Call", args);
                }

                protected override void CloneTo (CloneContext context, Expression target)
                {
                        // Nothing to clone
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        //
                        // We are born fully resolved
                        //
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        mg.EmitCall (ec, arguments);
                }

                public MethodGroupExpr Method {
                        get { return mg; }
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        foreach (Argument a in arguments)
                                a.Expr.MutateHoistedGenericType (storey);

                        mg.MutateHoistedGenericType (storey);
                }
        }

        public class ParenthesizedExpression : Expression
        {
                public Expression Expr;

                public ParenthesizedExpression (Expression expr)
                {
                        Expr = expr;
                        loc = expr.Location;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        Expr = Expr.Resolve (ec);
                        return Expr;
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        return Expr.DoResolveLValue (ec, right_side);
                }

                public override void Emit (EmitContext ec)
                {
                        throw new Exception ("Should not happen");
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        ParenthesizedExpression target = (ParenthesizedExpression) t;

                        target.Expr = Expr.Clone (clonectx);
                }
        }
        
        //
        //   Unary implements unary expressions.
        //
        public class Unary : Expression {
                public enum Operator : byte {
                        UnaryPlus, UnaryNegation, LogicalNot, OnesComplement,
                        AddressOf,  TOP
                }

                static Type [] [] predefined_operators;

                public readonly Operator Oper;
                public Expression Expr;
                Expression enum_conversion;

                public Unary (Operator op, Expression expr)
                {
                        Oper = op;
                        Expr = expr;
                        loc = expr.Location;
                }

                // <summary>
                //   This routine will attempt to simplify the unary expression when the
                //   argument is a constant.
                // </summary>
                Constant TryReduceConstant (EmitContext ec, Constant e)
                {
                        if (e is EmptyConstantCast)
                                return TryReduceConstant (ec, ((EmptyConstantCast) e).child);
                        
                        if (e is SideEffectConstant) {
                                Constant r = TryReduceConstant (ec, ((SideEffectConstant) e).value);
                                return r == null ? null : new SideEffectConstant (r, e, r.Location);
                        }

                        Type expr_type = e.Type;
                        
                        switch (Oper){
                        case Operator.UnaryPlus:
                                // Unary numeric promotions
                                if (expr_type == TypeManager.byte_type)
                                        return new IntConstant (((ByteConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.sbyte_type)
                                        return new IntConstant (((SByteConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.short_type)
                                        return new IntConstant (((ShortConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.ushort_type)
                                        return new IntConstant (((UShortConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.char_type)
                                        return new IntConstant (((CharConstant)e).Value, e.Location);
                                
                                // Predefined operators
                                if (expr_type == TypeManager.int32_type || expr_type == TypeManager.uint32_type ||
                                    expr_type == TypeManager.int64_type || expr_type == TypeManager.uint64_type ||
                                    expr_type == TypeManager.float_type || expr_type == TypeManager.double_type ||
                                    expr_type == TypeManager.decimal_type) {
                                        return e;
                                }
                                
                                return null;
                                
                        case Operator.UnaryNegation:
                                // Unary numeric promotions
                                if (expr_type == TypeManager.byte_type)
                                        return new IntConstant (-((ByteConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.sbyte_type)
                                        return new IntConstant (-((SByteConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.short_type)
                                        return new IntConstant (-((ShortConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.ushort_type)
                                        return new IntConstant (-((UShortConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.char_type)
                                        return new IntConstant (-((CharConstant)e).Value, e.Location);
                                
                                // Predefined operators
                                if (expr_type == TypeManager.int32_type) {
                                        int value = ((IntConstant)e).Value;
                                        if (value == int.MinValue) {
                                                if (ec.ConstantCheckState) {
                                                        ConstantFold.Error_CompileTimeOverflow (loc);
                                                        return null;
                                                }
                                                return e;
                                        }
                                        return new IntConstant (-value, e.Location);
                                }
                                if (expr_type == TypeManager.int64_type) {
                                        long value = ((LongConstant)e).Value;
                                        if (value == long.MinValue) {
                                                if (ec.ConstantCheckState) {
                                                        ConstantFold.Error_CompileTimeOverflow (loc);
                                                        return null;
                                                }
                                                return e;
                                        }
                                        return new LongConstant (-value, e.Location);
                                }
                                
                                if (expr_type == TypeManager.uint32_type) {
                                        UIntLiteral uil = e as UIntLiteral;
                                        if (uil != null) {
                                                if (uil.Value == 2147483648)
                                                        return new IntLiteral (int.MinValue, e.Location);
                                                return new LongLiteral (-uil.Value, e.Location);
                                        }
                                        return new LongConstant (-((UIntConstant)e).Value, e.Location);
                                }
                                
                                if (expr_type == TypeManager.uint64_type) {
                                        ULongLiteral ull = e as ULongLiteral;
                                        if (ull != null && ull.Value == 9223372036854775808)
                                                return new LongLiteral (long.MinValue, e.Location);
                                        return null;
                                }
                                
                                if (expr_type == TypeManager.float_type) {
                                        FloatLiteral fl = e as FloatLiteral;
                                        // For better error reporting
                                        if (fl != null)
                                                return new FloatLiteral (-fl.Value, e.Location);

                                        return new FloatConstant (-((FloatConstant)e).Value, e.Location);
                                }
                                if (expr_type == TypeManager.double_type) {
                                        DoubleLiteral dl = e as DoubleLiteral;
                                        // For better error reporting
                                        if (dl != null)
                                                return new DoubleLiteral (-dl.Value, e.Location);

                                        return new DoubleConstant (-((DoubleConstant)e).Value, e.Location);
                                }
                                if (expr_type == TypeManager.decimal_type)
                                        return new DecimalConstant (-((DecimalConstant)e).Value, e.Location);
                                
                                return null;
                                
                        case Operator.LogicalNot:
                                if (expr_type != TypeManager.bool_type)
                                        return null;
                                
                                bool b = (bool)e.GetValue ();
                                return new BoolConstant (!b, e.Location);
                                
                        case Operator.OnesComplement:
                                // Unary numeric promotions
                                if (expr_type == TypeManager.byte_type)
                                        return new IntConstant (~((ByteConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.sbyte_type)
                                        return new IntConstant (~((SByteConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.short_type)
                                        return new IntConstant (~((ShortConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.ushort_type)
                                        return new IntConstant (~((UShortConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.char_type)
                                        return new IntConstant (~((CharConstant)e).Value, e.Location);
                                
                                // Predefined operators
                                if (expr_type == TypeManager.int32_type)
                                        return new IntConstant (~((IntConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.uint32_type)
                                        return new UIntConstant (~((UIntConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.int64_type)
                                        return new LongConstant (~((LongConstant)e).Value, e.Location);
                                if (expr_type == TypeManager.uint64_type){
                                        return new ULongConstant (~((ULongConstant)e).Value, e.Location);
                                }
                                if (e is EnumConstant) {
                                        e = TryReduceConstant (ec, ((EnumConstant)e).Child);
                                        if (e != null)
                                                e = new EnumConstant (e, expr_type);
                                        return e;
                                }
                                return null;
                        }
                        throw new Exception ("Can not constant fold: " + Oper.ToString());
                }
                
                protected Expression ResolveOperator (EmitContext ec, Expression expr)
                {
                        eclass = ExprClass.Value;

                        if (predefined_operators == null)
                                CreatePredefinedOperatorsTable ();

                        Type expr_type = expr.Type;
                        Expression best_expr;

                        //
                        // Primitive types first
                        //
                        if (TypeManager.IsPrimitiveType (expr_type)) {
                                best_expr = ResolvePrimitivePredefinedType (expr);
                                if (best_expr == null)
                                        return null;

                                type = best_expr.Type;
                                Expr = best_expr;
                                return this;
                        }

                        //
                        // E operator ~(E x);
                        //
                        if (Oper == Operator.OnesComplement && TypeManager.IsEnumType (expr_type))
                                return ResolveEnumOperator (ec, expr);

                        return ResolveUserType (ec, expr);
                }

                protected virtual Expression ResolveEnumOperator (EmitContext ec, Expression expr)
                {
                        Type underlying_type = TypeManager.GetEnumUnderlyingType (expr.Type);
                        Expression best_expr = ResolvePrimitivePredefinedType (EmptyCast.Create (expr, underlying_type));
                        if (best_expr == null)
                                return null;

                        Expr = best_expr;
                        enum_conversion = Convert.ExplicitNumericConversion (new EmptyExpression (best_expr.Type), underlying_type);
                        type = expr.Type;
                        return EmptyCast.Create (this, type);
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        return CreateExpressionTree (ec, null);
                }

                Expression CreateExpressionTree (EmitContext ec, MethodGroupExpr user_op)
                {
                        string method_name;
                        switch (Oper) {
                        case Operator.AddressOf:
                                Error_PointerInsideExpressionTree ();
                                return null;
                        case Operator.UnaryNegation:
                                if (ec.CheckState && user_op == null && !IsFloat (type))
                                        method_name = "NegateChecked";
                                else
                                        method_name = "Negate";
                                break;
                        case Operator.OnesComplement:
                        case Operator.LogicalNot:
                                method_name = "Not";
                                break;
                        case Operator.UnaryPlus:
                                method_name = "UnaryPlus";
                                break;
                        default:
                                throw new InternalErrorException ("Unknown unary operator " + Oper.ToString ());
                        }

                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (Expr.CreateExpressionTree (ec)));
                        if (user_op != null)
                                args.Add (new Argument (user_op.CreateExpressionTree (ec)));
                        return CreateExpressionFactoryCall (method_name, args);
                }

                static void CreatePredefinedOperatorsTable ()
                {
                        predefined_operators = new Type [(int) Operator.TOP] [];

                        //
                        // 7.6.1 Unary plus operator
                        //
                        predefined_operators [(int) Operator.UnaryPlus] = new Type [] {
                                TypeManager.int32_type, TypeManager.uint32_type,
                                TypeManager.int64_type, TypeManager.uint64_type,
                                TypeManager.float_type, TypeManager.double_type,
                                TypeManager.decimal_type
                        };

                        //
                        // 7.6.2 Unary minus operator
                        //
                        predefined_operators [(int) Operator.UnaryNegation] = new Type [] {
                                TypeManager.int32_type, 
                                TypeManager.int64_type,
                                TypeManager.float_type, TypeManager.double_type,
                                TypeManager.decimal_type
                        };

                        //
                        // 7.6.3 Logical negation operator
                        //
                        predefined_operators [(int) Operator.LogicalNot] = new Type [] {
                                TypeManager.bool_type
                        };

                        //
                        // 7.6.4 Bitwise complement operator
                        //
                        predefined_operators [(int) Operator.OnesComplement] = new Type [] {
                                TypeManager.int32_type, TypeManager.uint32_type,
                                TypeManager.int64_type, TypeManager.uint64_type
                        };
                }

                //
                // Unary numeric promotions
                //
                static Expression DoNumericPromotion (Operator op, Expression expr)
                {
                        Type expr_type = expr.Type;
                        if ((op == Operator.UnaryPlus || op == Operator.UnaryNegation || op == Operator.OnesComplement) &&
                                expr_type == TypeManager.byte_type || expr_type == TypeManager.sbyte_type ||
                                expr_type == TypeManager.short_type || expr_type == TypeManager.ushort_type ||
                                expr_type == TypeManager.char_type)
                                return Convert.ImplicitNumericConversion (expr, TypeManager.int32_type);

                        if (op == Operator.UnaryNegation && expr_type == TypeManager.uint32_type)
                                return Convert.ImplicitNumericConversion (expr, TypeManager.int64_type);

                        return expr;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (Oper == Operator.AddressOf) {
                                return ResolveAddressOf (ec);
                        }

                        Expr = Expr.Resolve (ec);
                        if (Expr == null)
                                return null;

                        if (TypeManager.IsNullableType (Expr.Type))
                                return new Nullable.LiftedUnaryOperator (Oper, Expr).Resolve (ec);

                        //
                        // Attempt to use a constant folding operation.
                        //
                        Constant cexpr = Expr as Constant;
                        if (cexpr != null) {
                                cexpr = TryReduceConstant (ec, cexpr);
                                if (cexpr != null)
                                        return cexpr;
                        }

                        Expression expr = ResolveOperator (ec, Expr);
                        if (expr == null)
                                Error_OperatorCannotBeApplied (loc, OperName (Oper), Expr.Type);
                        
                        //
                        // Reduce unary operator on predefined types
                        //
                        if (expr == this && Oper == Operator.UnaryPlus)
                                return Expr;

                        return expr;
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right)
                {
                        return null;
                }

                public override void Emit (EmitContext ec)
                {
                        EmitOperator (ec, type);
                }

                protected void EmitOperator (EmitContext ec, Type type)
                {
                        ILGenerator ig = ec.ig;

                        switch (Oper) {
                        case Operator.UnaryPlus:
                                Expr.Emit (ec);
                                break;
                                
                        case Operator.UnaryNegation:
                                if (ec.CheckState && !IsFloat (type)) {
                                        ig.Emit (OpCodes.Ldc_I4_0);
                                        if (type == TypeManager.int64_type)
                                                ig.Emit (OpCodes.Conv_U8);
                                        Expr.Emit (ec);
                                        ig.Emit (OpCodes.Sub_Ovf);
                                } else {
                                        Expr.Emit (ec);
                                        ig.Emit (OpCodes.Neg);
                                }
                                
                                break;
                                
                        case Operator.LogicalNot:
                                Expr.Emit (ec);
                                ig.Emit (OpCodes.Ldc_I4_0);
                                ig.Emit (OpCodes.Ceq);
                                break;
                                
                        case Operator.OnesComplement:
                                Expr.Emit (ec);
                                ig.Emit (OpCodes.Not);
                                break;
                                
                        case Operator.AddressOf:
                                ((IMemoryLocation)Expr).AddressOf (ec, AddressOp.LoadStore);
                                break;
                                
                        default:
                                throw new Exception ("This should not happen: Operator = "
                                                     + Oper.ToString ());
                        }

                        //
                        // Same trick as in Binary expression
                        //
                        if (enum_conversion != null)
                                enum_conversion.Emit (ec);
                }

                public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
                {
                        if (Oper == Operator.LogicalNot)
                                Expr.EmitBranchable (ec, target, !on_true);
                        else
                                base.EmitBranchable (ec, target, on_true);
                }

                public override void EmitSideEffect (EmitContext ec)
                {
                        Expr.EmitSideEffect (ec);
                }

                public static void Error_OperatorCannotBeApplied (Location loc, string oper, Type t)
                {
                        Report.Error (23, loc, "The `{0}' operator cannot be applied to operand of type `{1}'",
                                oper, TypeManager.CSharpName (t));
                }

                static bool IsFloat (Type t)
                {
                        return t == TypeManager.float_type || t == TypeManager.double_type;
                }

                //
                // Returns a stringified representation of the Operator
                //
                public static string OperName (Operator oper)
                {
                        switch (oper) {
                        case Operator.UnaryPlus:
                                return "+";
                        case Operator.UnaryNegation:
                                return "-";
                        case Operator.LogicalNot:
                                return "!";
                        case Operator.OnesComplement:
                                return "~";
                        case Operator.AddressOf:
                                return "&";
                        }

                        throw new NotImplementedException (oper.ToString ());
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        type = storey.MutateType (type);
                        Expr.MutateHoistedGenericType (storey);
                }

                Expression ResolveAddressOf (EmitContext ec)
                {
                        if (!ec.InUnsafe)
                                UnsafeError (loc);

                        Expr = Expr.DoResolveLValue (ec, EmptyExpression.UnaryAddress);
                        if (Expr == null || Expr.eclass != ExprClass.Variable) {
                                Error (211, "Cannot take the address of the given expression");
                                return null;
                        }

                        if (!TypeManager.VerifyUnManaged (Expr.Type, loc)) {
                                return null;
                        }

                        IVariableReference vr = Expr as IVariableReference;
                        bool is_fixed;
                        if (vr != null) {
                                VariableInfo vi = vr.VariableInfo;
                                if (vi != null) {
                                        if (vi.LocalInfo != null)
                                                vi.LocalInfo.Used = true;

                                        //
                                        // A variable is considered definitely assigned if you take its address.
                                        //
                                        vi.SetAssigned (ec);
                                }

                                is_fixed = vr.IsFixed;
                                vr.SetHasAddressTaken ();

                                if (vr.IsHoisted) {
                                        AnonymousMethodExpression.Error_AddressOfCapturedVar (vr, loc);
                                }
                        } else {
                                IFixedExpression fe = Expr as IFixedExpression;
                                is_fixed = fe != null && fe.IsFixed;
                        }

                        if (!is_fixed && !ec.InFixedInitializer) {
                                Error (212, "You can only take the address of unfixed expression inside of a fixed statement initializer");
                        }

                        type = TypeManager.GetPointerType (Expr.Type);
                        eclass = ExprClass.Value;
                        return this;
                }

                Expression ResolvePrimitivePredefinedType (Expression expr)
                {
                        expr = DoNumericPromotion (Oper, expr);
                        Type expr_type = expr.Type;
                        Type[] predefined = predefined_operators [(int) Oper];
                        foreach (Type t in predefined) {
                                if (t == expr_type)
                                        return expr;
                        }
                        return null;
                }

                //
                // Perform user-operator overload resolution
                //
                protected virtual Expression ResolveUserOperator (EmitContext ec, Expression expr)
                {
                        CSharp.Operator.OpType op_type;
                        switch (Oper) {
                        case Operator.LogicalNot:
                                op_type = CSharp.Operator.OpType.LogicalNot; break;
                        case Operator.OnesComplement:
                                op_type = CSharp.Operator.OpType.OnesComplement; break;
                        case Operator.UnaryNegation:
                                op_type = CSharp.Operator.OpType.UnaryNegation; break;
                        case Operator.UnaryPlus:
                                op_type = CSharp.Operator.OpType.UnaryPlus; break;
                        default:
                                throw new InternalErrorException (Oper.ToString ());
                        }

                        string op_name = CSharp.Operator.GetMetadataName (op_type);
                        MethodGroupExpr user_op = MemberLookup (ec.ContainerType, expr.Type, op_name, MemberTypes.Method, AllBindingFlags, expr.Location) as MethodGroupExpr;
                        if (user_op == null)
                                return null;

                        ArrayList args = new ArrayList (1);
                        args.Add (new Argument (expr));
                        user_op = user_op.OverloadResolve (ec, ref args, false, expr.Location);

                        if (user_op == null)
                                return null;

                        Expr = ((Argument) args [0]).Expr;
                        return new UserOperatorCall (user_op, args, CreateExpressionTree, expr.Location);
                }

                //
                // Unary user type overload resolution
                //
                Expression ResolveUserType (EmitContext ec, Expression expr)
                {
                        Expression best_expr = ResolveUserOperator (ec, expr);
                        if (best_expr != null)
                                return best_expr;

                        Type[] predefined = predefined_operators [(int) Oper];
                        foreach (Type t in predefined) {
                                Expression oper_expr = Convert.UserDefinedConversion (ec, expr, t, expr.Location, false);
                                if (oper_expr == null)
                                        continue;

                                //
                                // decimal type is predefined but has user-operators
                                //
                                if (oper_expr.Type == TypeManager.decimal_type)
                                        oper_expr = ResolveUserType (ec, oper_expr);
                                else
                                        oper_expr = ResolvePrimitivePredefinedType (oper_expr);

                                if (oper_expr == null)
                                        continue;

                                if (best_expr == null) {
                                        best_expr = oper_expr;
                                        continue;
                                }

                                int result = MethodGroupExpr.BetterTypeConversion (ec, best_expr.Type, t);
                                if (result == 0) {
                                        Report.Error (35, loc, "Operator `{0}' is ambiguous on an operand of type `{1}'",
                                                OperName (Oper), TypeManager.CSharpName (expr.Type));
                                        break;
                                }

                                if (result == 2)
                                        best_expr = oper_expr;
                        }
                        
                        if (best_expr == null)
                                return null;
                        
                        //
                        // HACK: Decimal user-operator is included in standard operators
                        //
                        if (best_expr.Type == TypeManager.decimal_type)
                                return best_expr;                       

                        Expr = best_expr;
                        type = best_expr.Type;
                        return this;                    
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Unary target = (Unary) t;

                        target.Expr = Expr.Clone (clonectx);
                }
        }

        //
        // Unary operators are turned into Indirection expressions
        // after semantic analysis (this is so we can take the address
        // of an indirection).
        //
        public class Indirection : Expression, IMemoryLocation, IAssignMethod, IFixedExpression {
                Expression expr;
                LocalTemporary temporary;
                bool prepared;
                
                public Indirection (Expression expr, Location l)
                {
                        this.expr = expr;
                        loc = l;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        Error_PointerInsideExpressionTree ();
                        return null;
                }
                
                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Indirection target = (Indirection) t;
                        target.expr = expr.Clone (clonectx);
                }               
                
                public override void Emit (EmitContext ec)
                {
                        if (!prepared)
                                expr.Emit (ec);
                        
                        LoadFromPtr (ec.ig, Type);
                }

                public void Emit (EmitContext ec, bool leave_copy)
                {
                        Emit (ec);
                        if (leave_copy) {
                                ec.ig.Emit (OpCodes.Dup);
                                temporary = new LocalTemporary (expr.Type);
                                temporary.Store (ec);
                        }
                }
                
                public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
                {
                        prepared = prepare_for_load;
                        
                        expr.Emit (ec);

                        if (prepare_for_load)
                                ec.ig.Emit (OpCodes.Dup);
                        
                        source.Emit (ec);
                        if (leave_copy) {
                                ec.ig.Emit (OpCodes.Dup);
                                temporary = new LocalTemporary (expr.Type);
                                temporary.Store (ec);
                        }
                        
                        StoreFromPtr (ec.ig, type);
                        
                        if (temporary != null) {
                                temporary.Emit (ec);
                                temporary.Release (ec);
                        }
                }
                
                public void AddressOf (EmitContext ec, AddressOp Mode)
                {
                        expr.Emit (ec);
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        return DoResolve (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        expr = expr.Resolve (ec);
                        if (expr == null)
                                return null;

                        if (!ec.InUnsafe)
                                UnsafeError (loc);

                        if (!expr.Type.IsPointer) {
                                Error (193, "The * or -> operator must be applied to a pointer");
                                return null;
                        }

                        if (expr.Type == TypeManager.void_ptr_type) {
                                Error (242, "The operation in question is undefined on void pointers");
                                return null;
                        }

                        type = TypeManager.GetElementType (expr.Type);
                        eclass = ExprClass.Variable;
                        return this;
                }

                public bool IsFixed {
                        get { return true; }
                }

                public override string ToString ()
                {
                        return "*(" + expr + ")";
                }
        }
        
        /// <summary>
        ///   Unary Mutator expressions (pre and post ++ and --)
        /// </summary>
        ///
        /// <remarks>
        ///   UnaryMutator implements ++ and -- expressions.   It derives from
        ///   ExpressionStatement becuase the pre/post increment/decrement
        ///   operators can be used in a statement context.
        ///
        /// FIXME: Idea, we could split this up in two classes, one simpler
        /// for the common case, and one with the extra fields for more complex
        /// classes (indexers require temporary access;  overloaded require method)
        ///
        /// </remarks>
        public class UnaryMutator : ExpressionStatement {
                [Flags]
                public enum Mode : byte {
                        IsIncrement    = 0,
                        IsDecrement    = 1,
                        IsPre          = 0,
                        IsPost         = 2,
                        
                        PreIncrement   = 0,
                        PreDecrement   = IsDecrement,
                        PostIncrement  = IsPost,
                        PostDecrement  = IsPost | IsDecrement
                }

                Mode mode;
                bool is_expr = false;
                bool recurse = false;

                Expression expr;

                //
                // This is expensive for the simplest case.
                //
                UserOperatorCall method;

                public UnaryMutator (Mode m, Expression e)
                {
                        mode = m;
                        loc = e.Location;
                        expr = e;
                }

                static string OperName (Mode mode)
                {
                        return (mode == Mode.PreIncrement || mode == Mode.PostIncrement) ?
                                "++" : "--";
                }

                /// <summary>
                ///   Returns whether an object of type `t' can be incremented
                ///   or decremented with add/sub (ie, basically whether we can
                ///   use pre-post incr-decr operations on it, but it is not a
                ///   System.Decimal, which we require operator overloading to catch)
                /// </summary>
                static bool IsIncrementableNumber (Type t)
                {
                        return (t == TypeManager.sbyte_type) ||
                                (t == TypeManager.byte_type) ||
                                (t == TypeManager.short_type) ||
                                (t == TypeManager.ushort_type) ||
                                (t == TypeManager.int32_type) ||
                                (t == TypeManager.uint32_type) ||
                                (t == TypeManager.int64_type) ||
                                (t == TypeManager.uint64_type) ||
                                (t == TypeManager.char_type) ||
                                (TypeManager.IsSubclassOf (t, TypeManager.enum_type)) ||
                                (t == TypeManager.float_type) ||
                                (t == TypeManager.double_type) ||
                                (t.IsPointer && t != TypeManager.void_ptr_type);
                }

                Expression ResolveOperator (EmitContext ec)
                {
                        type = expr.Type;
                        
                        //
                        // The operand of the prefix/postfix increment decrement operators
                        // should be an expression that is classified as a variable,
                        // a property access or an indexer access
                        //
                        if (expr.eclass == ExprClass.Variable || expr.eclass == ExprClass.IndexerAccess || expr.eclass == ExprClass.PropertyAccess) {
                                expr = expr.ResolveLValue (ec, expr, Location);
                        } else {
                                Report.Error (1059, loc, "The operand of an increment or decrement operator must be a variable, property or indexer");
                        }

                        //
                        // Step 1: Perform Operator Overload location
                        //
                        MethodGroupExpr mg;
                        string op_name;
                        
                        if (mode == Mode.PreIncrement || mode == Mode.PostIncrement)
                                op_name = Operator.GetMetadataName (Operator.OpType.Increment);
                        else
                                op_name = Operator.GetMetadataName (Operator.OpType.Decrement);

                        mg = MemberLookup (ec.ContainerType, type, op_name, MemberTypes.Method, AllBindingFlags, loc) as MethodGroupExpr;

                        if (mg != null) {
                                ArrayList args = new ArrayList (1);
                                args.Add (new Argument (expr, Argument.AType.Expression));
                                mg = mg.OverloadResolve (ec, ref args, false, loc);
                                if (mg == null)
                                        return null;

                                method = new UserOperatorCall (mg, args, null, loc);
                                Convert.ImplicitConversionRequired (ec, method, type, loc);
                                return this;
                        }

                        if (!IsIncrementableNumber (type)) {
                                Error (187, "No such operator '" + OperName (mode) + "' defined for type '" +
                                           TypeManager.CSharpName (type) + "'");
                                return null;
                        }

                        return this;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        return new SimpleAssign (this, this).CreateExpressionTree (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        expr = expr.Resolve (ec);
                        
                        if (expr == null)
                                return null;

                        eclass = ExprClass.Value;

                        if (TypeManager.IsNullableType (expr.Type))
                                return new Nullable.LiftedUnaryMutator (mode, expr, loc).Resolve (ec);

                        return ResolveOperator (ec);
                }

                //
                // Loads the proper "1" into the stack based on the type, then it emits the
                // opcode for the operation requested
                //
                void LoadOneAndEmitOp (EmitContext ec, Type t)
                {
                        //
                        // Measure if getting the typecode and using that is more/less efficient
                        // that comparing types.  t.GetTypeCode() is an internal call.
                        //
                        ILGenerator ig = ec.ig;
                                                     
                        if (t == TypeManager.uint64_type || t == TypeManager.int64_type)
                                LongConstant.EmitLong (ig, 1);
                        else if (t == TypeManager.double_type)
                                ig.Emit (OpCodes.Ldc_R8, 1.0);
                        else if (t == TypeManager.float_type)
                                ig.Emit (OpCodes.Ldc_R4, 1.0F);
                        else if (t.IsPointer){
                                Type et = TypeManager.GetElementType (t);
                                int n = GetTypeSize (et);
                                
                                if (n == 0)
                                        ig.Emit (OpCodes.Sizeof, et);
                                else {
                                        IntConstant.EmitInt (ig, n);
                                        ig.Emit (OpCodes.Conv_I);
                                }
                        } else 
                                ig.Emit (OpCodes.Ldc_I4_1);

                        //
                        // Now emit the operation
                        //

                        Binary.Operator op = (mode & Mode.IsDecrement) != 0 ? Binary.Operator.Subtraction : Binary.Operator.Addition;
                        Binary.EmitOperatorOpcode (ec, op, t);

                        if (t == TypeManager.sbyte_type){
                                if (ec.CheckState)
                                        ig.Emit (OpCodes.Conv_Ovf_I1);
                                else
                                        ig.Emit (OpCodes.Conv_I1);
                        } else if (t == TypeManager.byte_type){
                                if (ec.CheckState)
                                        ig.Emit (OpCodes.Conv_Ovf_U1);
                                else
                                        ig.Emit (OpCodes.Conv_U1);
                        } else if (t == TypeManager.short_type){
                                if (ec.CheckState)
                                        ig.Emit (OpCodes.Conv_Ovf_I2);
                                else
                                        ig.Emit (OpCodes.Conv_I2);
                        } else if (t == TypeManager.ushort_type || t == TypeManager.char_type){
                                if (ec.CheckState)
                                        ig.Emit (OpCodes.Conv_Ovf_U2);
                                else
                                        ig.Emit (OpCodes.Conv_U2);
                        }
                        
                }

                void EmitCode (EmitContext ec, bool is_expr)
                {
                        recurse = true;
                        this.is_expr = is_expr;
                        ((IAssignMethod) expr).EmitAssign (ec, this, is_expr && (mode == Mode.PreIncrement || mode == Mode.PreDecrement), true);
                }

                public override void Emit (EmitContext ec)
                {
                        //
                        // We use recurse to allow ourselfs to be the source
                        // of an assignment. This little hack prevents us from
                        // having to allocate another expression
                        //
                        if (recurse) {
                                ((IAssignMethod) expr).Emit (ec, is_expr && (mode == Mode.PostIncrement || mode == Mode.PostDecrement));
                                if (method == null)
                                        LoadOneAndEmitOp (ec, expr.Type);
                                else
                                        ec.ig.Emit (OpCodes.Call, (MethodInfo)method.Method);
                                recurse = false;
                                return;
                        }

                        EmitCode (ec, true);
                }

                public override void EmitStatement (EmitContext ec)
                {
                        EmitCode (ec, false);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        UnaryMutator target = (UnaryMutator) t;

                        target.expr = expr.Clone (clonectx);
                }
        }

        /// <summary>
        ///   Base class for the `Is' and `As' classes. 
        /// </summary>
        ///
        /// <remarks>
        ///   FIXME: Split this in two, and we get to save the `Operator' Oper
        ///   size. 
        /// </remarks>
        public abstract class Probe : Expression {
                public Expression ProbeType;
                protected Expression expr;
                protected TypeExpr probe_type_expr;
                
                public Probe (Expression expr, Expression probe_type, Location l)
                {
                        ProbeType = probe_type;
                        loc = l;
                        this.expr = expr;
                }

                public Expression Expr {
                        get {
                                return expr;
                        }
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        probe_type_expr = ProbeType.ResolveAsTypeTerminal (ec, false);
                        if (probe_type_expr == null)
                                return null;

                        expr = expr.Resolve (ec);
                        if (expr == null)
                                return null;

                        if ((probe_type_expr.Type.Attributes & Class.StaticClassAttribute) == Class.StaticClassAttribute) {
                                Report.Error (-244, loc, "The `{0}' operator cannot be applied to an operand of a static type",
                                        OperatorName);
                        }
                        
                        if (expr.Type.IsPointer || probe_type_expr.Type.IsPointer) {
                                Report.Error (244, loc, "The `{0}' operator cannot be applied to an operand of pointer type",
                                        OperatorName);
                                return null;
                        }

                        if (expr.Type == TypeManager.anonymous_method_type) {
                                Report.Error (837, loc, "The `{0}' operator cannot be applied to a lambda expression or anonymous method",
                                        OperatorName);
                                return null;
                        }

                        return this;
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        expr.MutateHoistedGenericType (storey);
                        probe_type_expr.MutateHoistedGenericType (storey);
                }

                protected abstract string OperatorName { get; }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Probe target = (Probe) t;

                        target.expr = expr.Clone (clonectx);
                        target.ProbeType = ProbeType.Clone (clonectx);
                }

        }

        /// <summary>
        ///   Implementation of the `is' operator.
        /// </summary>
        public class Is : Probe {
                Nullable.Unwrap expr_unwrap;

                public Is (Expression expr, Expression probe_type, Location l)
                        : base (expr, probe_type, l)
                {
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (expr.CreateExpressionTree (ec)));
                        args.Add (new Argument (new TypeOf (probe_type_expr, loc)));
                        return CreateExpressionFactoryCall ("TypeIs", args);
                }
                
                public override void Emit (EmitContext ec)
                {
                        ILGenerator ig = ec.ig;
                        if (expr_unwrap != null) {
                                expr_unwrap.EmitCheck (ec);
                                return;
                        }

                        expr.Emit (ec);
                        ig.Emit (OpCodes.Isinst, probe_type_expr.Type);
                        ig.Emit (OpCodes.Ldnull);
                        ig.Emit (OpCodes.Cgt_Un);
                }

                public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
                {
                        ILGenerator ig = ec.ig;
                        if (expr_unwrap != null) {
                                expr_unwrap.EmitCheck (ec);
                        } else {
                                expr.Emit (ec);
                                ig.Emit (OpCodes.Isinst, probe_type_expr.Type);
                        }                       
                        ig.Emit (on_true ? OpCodes.Brtrue : OpCodes.Brfalse, target);
                }
                
                Expression CreateConstantResult (bool result)
                {
                        if (result)
                                Report.Warning (183, 1, loc, "The given expression is always of the provided (`{0}') type",
                                        TypeManager.CSharpName (probe_type_expr.Type));
                        else
                                Report.Warning (184, 1, loc, "The given expression is never of the provided (`{0}') type",
                                        TypeManager.CSharpName (probe_type_expr.Type));

                        return ReducedExpression.Create (new BoolConstant (result, loc), this);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (base.DoResolve (ec) == null)
                                return null;

                        Type d = expr.Type;
                        bool d_is_nullable = false;

                        //
                        // If E is a method group or the null literal, or if the type of E is a reference
                        // type or a nullable type and the value of E is null, the result is false
                        //
                        if (expr.IsNull || expr.eclass == ExprClass.MethodGroup)
                                return CreateConstantResult (false);

                        if (TypeManager.IsNullableType (d) && !TypeManager.ContainsGenericParameters (d)) {
                                d = TypeManager.GetTypeArguments (d) [0];
                                d_is_nullable = true;
                        }

                        type = TypeManager.bool_type;
                        eclass = ExprClass.Value;
                        Type t = probe_type_expr.Type;
                        bool t_is_nullable = false;
                        if (TypeManager.IsNullableType (t) && !TypeManager.ContainsGenericParameters (t)) {
                                t = TypeManager.GetTypeArguments (t) [0];
                                t_is_nullable = true;
                        }

                        if (TypeManager.IsStruct (t)) {
                                if (d == t) {
                                        //
                                        // D and T are the same value types but D can be null
                                        //
                                        if (d_is_nullable && !t_is_nullable) {
                                                expr_unwrap = Nullable.Unwrap.Create (expr, false);
                                                return this;
                                        }
                                        
                                        //
                                        // The result is true if D and T are the same value types
                                        //
                                        return CreateConstantResult (true);
                                }

                                if (TypeManager.IsGenericParameter (d))
                                        return ResolveGenericParameter (t, d);

                                //
                                // An unboxing conversion exists
                                //
                                if (Convert.ExplicitReferenceConversionExists (d, t))
                                        return this;
                        } else {
                                if (TypeManager.IsGenericParameter (t))
                                        return ResolveGenericParameter (d, t);

                                if (TypeManager.IsStruct (d)) {
                                        bool temp;
                                        if (Convert.ImplicitBoxingConversionExists (expr, t, out temp))
                                                return CreateConstantResult (true);
                                } else {
                                        if (TypeManager.IsGenericParameter (d))
                                                return ResolveGenericParameter (t, d);

                                        if (TypeManager.ContainsGenericParameters (d))
                                                return this;

                                        if (Convert.ImplicitReferenceConversionExists (expr, t) ||
                                                Convert.ExplicitReferenceConversionExists (d, t)) {
                                                return this;
                                        }
                                }
                        }

                        return CreateConstantResult (false);
                }

                Expression ResolveGenericParameter (Type d, Type t)
                {
                        GenericConstraints constraints = TypeManager.GetTypeParameterConstraints (t);
                        if (constraints != null) {
                                if (constraints.IsReferenceType && TypeManager.IsStruct (d))
                                        return CreateConstantResult (false);

                                if (constraints.IsValueType && !TypeManager.IsStruct (d))
                                        return CreateConstantResult (TypeManager.IsEqual (d, t));
                        }

                        if (!TypeManager.IsReferenceType (expr.Type))
                                expr = new BoxedCast (expr, d);

                        return this;
                }
                
                protected override string OperatorName {
                        get { return "is"; }
                }
        }

        /// <summary>
        ///   Implementation of the `as' operator.
        /// </summary>
        public class As : Probe {
                bool do_isinst;
                Expression resolved_type;
                
                public As (Expression expr, Expression probe_type, Location l)
                        : base (expr, probe_type, l)
                {
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (expr.CreateExpressionTree (ec)));
                        args.Add (new Argument (new TypeOf (probe_type_expr, loc)));
                        return CreateExpressionFactoryCall ("TypeAs", args);
                }

                public override void Emit (EmitContext ec)
                {
                        ILGenerator ig = ec.ig;

                        expr.Emit (ec);

                        if (do_isinst)
                                ig.Emit (OpCodes.Isinst, type);

#if GMCS_SOURCE
                        if (TypeManager.IsGenericParameter (type) || TypeManager.IsNullableType (type))
                                ig.Emit (OpCodes.Unbox_Any, type);
#endif
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        // Because expr is modified
                        if (eclass != ExprClass.Invalid)
                                return this;

                        if (resolved_type == null) {
                                resolved_type = base.DoResolve (ec);

                                if (resolved_type == null)
                                        return null;
                        }

                        type = probe_type_expr.Type;
                        eclass = ExprClass.Value;
                        Type etype = expr.Type;

                        if (!TypeManager.IsReferenceType (type) && !TypeManager.IsNullableType (type)) {
                                if (probe_type_expr is TypeParameterExpr) {
                                        Report.Error (413, loc,
                                                "The `as' operator cannot be used with a non-reference type parameter `{0}'. Consider adding `class' or a reference type constraint",
                                                probe_type_expr.GetSignatureForError ());
                                } else {
                                        Report.Error (77, loc,
                                                "The `as' operator cannot be used with a non-nullable value type `{0}'",
                                                TypeManager.CSharpName (type));
                                }
                                return null;
                        }

                        if (expr.IsNull && TypeManager.IsNullableType (type)) {
                                return Nullable.LiftedNull.CreateFromExpression (this);
                        }
                        
                        Expression e = Convert.ImplicitConversion (ec, expr, type, loc);
                        if (e != null){
                                expr = e;
                                do_isinst = false;
                                return this;
                        }

                        if (Convert.ExplicitReferenceConversionExists (etype, type)){
                                if (TypeManager.IsGenericParameter (etype))
                                        expr = new BoxedCast (expr, etype);

                                do_isinst = true;
                                return this;
                        }

                        if (TypeManager.ContainsGenericParameters (etype) ||
                            TypeManager.ContainsGenericParameters (type)) {
                                expr = new BoxedCast (expr, etype);
                                do_isinst = true;
                                return this;
                        }

                        Report.Error (39, loc, "Cannot convert type `{0}' to `{1}' via a built-in conversion",
                                TypeManager.CSharpName (etype), TypeManager.CSharpName (type));

                        return null;
                }

                protected override string OperatorName {
                        get { return "as"; }
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        type = storey.MutateType (type);
                        base.MutateHoistedGenericType (storey);
                }
        
                public override bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
                {
                        return expr.GetAttributableValue (ec, value_type, out value);
                }
        }
        
        /// <summary>
        ///   This represents a typecast in the source language.
        ///
        ///   FIXME: Cast expressions have an unusual set of parsing
        ///   rules, we need to figure those out.
        /// </summary>
        public class Cast : Expression {
                Expression target_type;
                Expression expr;
                        
                public Cast (Expression cast_type, Expression expr)
                        : this (cast_type, expr, cast_type.Location)
                {
                }

                public Cast (Expression cast_type, Expression expr, Location loc)
                {
                        this.target_type = cast_type;
                        this.expr = expr;
                        this.loc = loc;
                }

                public Expression TargetType {
                        get { return target_type; }
                }

                public Expression Expr {
                        get { return expr; }
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        expr = expr.Resolve (ec);
                        if (expr == null)
                                return null;

                        TypeExpr target = target_type.ResolveAsTypeTerminal (ec, false);
                        if (target == null)
                                return null;

                        type = target.Type;

                        if (type.IsAbstract && type.IsSealed) {
                                Report.Error (716, loc, "Cannot convert to static type `{0}'", TypeManager.CSharpName (type));
                                return null;
                        }

                        eclass = ExprClass.Value;

                        Constant c = expr as Constant;
                        if (c != null) {
                                c = c.TryReduce (ec, type, loc);
                                if (c != null)
                                        return c;
                        }

                        if (type.IsPointer && !ec.InUnsafe) {
                                UnsafeError (loc);
                                return null;
                        }
                        expr = Convert.ExplicitConversion (ec, expr, type, loc);
                        return expr;
                }
                
                public override void Emit (EmitContext ec)
                {
                        throw new Exception ("Should not happen");
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Cast target = (Cast) t;

                        target.target_type = target_type.Clone (clonectx);
                        target.expr = expr.Clone (clonectx);
                }
        }
        
        //
        // C# 2.0 Default value expression
        //
        public class DefaultValueExpression : Expression
        {
                sealed class DefaultValueNullLiteral : NullLiteral
                {
                        public DefaultValueNullLiteral (DefaultValueExpression expr)
                                : base (expr.type, expr.loc)
                        {
                        }

                        public override void Error_ValueCannotBeConverted (EmitContext ec, Location loc, Type t, bool expl)
                        {
                                Error_ValueCannotBeConvertedCore (ec, loc, t, expl);
                        }
                }


                Expression expr;

                public DefaultValueExpression (Expression expr, Location loc)
                {
                        this.expr = expr;
                        this.loc = loc;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (this));
                        args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
                        return CreateExpressionFactoryCall ("Constant", args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        TypeExpr texpr = expr.ResolveAsTypeTerminal (ec, false);
                        if (texpr == null)
                                return null;

                        type = texpr.Type;

                        if ((type.Attributes & Class.StaticClassAttribute) == Class.StaticClassAttribute) {
                                Report.Error (-244, loc, "The `default value' operator cannot be applied to an operand of a static type");
                        }

                        if (type.IsPointer)
                                return new NullLiteral (Location).ConvertImplicitly (type);

                        if (TypeManager.IsReferenceType (type))
                                return new DefaultValueNullLiteral (this);

                        Constant c = New.Constantify (type);
                        if (c != null)
                                return c;

                        eclass = ExprClass.Variable;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        LocalTemporary temp_storage = new LocalTemporary(type);

                        temp_storage.AddressOf(ec, AddressOp.LoadStore);
                        ec.ig.Emit(OpCodes.Initobj, type);
                        temp_storage.Emit(ec);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        type = storey.MutateType (type);
                }
                
                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        DefaultValueExpression target = (DefaultValueExpression) t;
                        
                        target.expr = expr.Clone (clonectx);
                }
        }

        /// <summary>
        ///   Binary operators
        /// </summary>
        public class Binary : Expression {

                protected class PredefinedOperator {
                        protected readonly Type left;
                        protected readonly Type right;
                        public readonly Operator OperatorsMask;
                        public Type ReturnType;

                        public PredefinedOperator (Type ltype, Type rtype, Operator op_mask)
                                : this (ltype, rtype, op_mask, ltype)
                        {
                        }

                        public PredefinedOperator (Type type, Operator op_mask, Type return_type)
                                : this (type, type, op_mask, return_type)
                        {
                        }

                        public PredefinedOperator (Type type, Operator op_mask)
                                : this (type, type, op_mask, type)
                        {
                        }

                        public PredefinedOperator (Type ltype, Type rtype, Operator op_mask, Type return_type)
                        {
                                if ((op_mask & Operator.ValuesOnlyMask) != 0)
                                        throw new InternalErrorException ("Only masked values can be used");

                                this.left = ltype;
                                this.right = rtype;
                                this.OperatorsMask = op_mask;
                                this.ReturnType = return_type;
                        }

                        public virtual Expression ConvertResult (EmitContext ec, Binary b)
                        {
                                b.type = ReturnType;

                                b.left = Convert.ImplicitConversion (ec, b.left, left, b.left.Location);
                                b.right = Convert.ImplicitConversion (ec, b.right, right, b.right.Location);

                                //
                                // A user operators does not support multiple user conversions, but decimal type
                                // is considered to be predefined type therefore we apply predefined operators rules
                                // and then look for decimal user-operator implementation
                                //
                                if (left == TypeManager.decimal_type)
                                        return b.ResolveUserOperator (ec, b.left.Type, b.right.Type);

                                return b;
                        }

                        public bool IsPrimitiveApplicable (Type ltype, Type rtype)
                        {
                                //
                                // We are dealing with primitive types only
                                //
                                return left == ltype && ltype == rtype;
                        }

                        public virtual bool IsApplicable (EmitContext ec, Expression lexpr, Expression rexpr)
                        {
                                if (TypeManager.IsEqual (left, lexpr.Type) &&
                                        TypeManager.IsEqual (right, rexpr.Type))
                                        return true;

                                return Convert.ImplicitConversionExists (ec, lexpr, left) &&
                                        Convert.ImplicitConversionExists (ec, rexpr, right);
                        }

                        public PredefinedOperator ResolveBetterOperator (EmitContext ec, PredefinedOperator best_operator)
                        {
                                int result = 0;
                                if (left != null && best_operator.left != null) {
                                        result = MethodGroupExpr.BetterTypeConversion (ec, best_operator.left, left);
                                }

                                //
                                // When second arguments are same as the first one, the result is same
                                //
                                if (right != null && (left != right || best_operator.left != best_operator.right)) {
                                        result |= MethodGroupExpr.BetterTypeConversion (ec, best_operator.right, right);
                                }

                                if (result == 0 || result > 2)
                                        return null;

                                return result == 1 ? best_operator : this;
                        }
                }

                class PredefinedStringOperator : PredefinedOperator {
                        public PredefinedStringOperator (Type type, Operator op_mask)
                                : base (type, op_mask, type)
                        {
                                ReturnType = TypeManager.string_type;
                        }

                        public PredefinedStringOperator (Type ltype, Type rtype, Operator op_mask)
                                : base (ltype, rtype, op_mask)
                        {
                                ReturnType = TypeManager.string_type;
                        }

                        public override Expression ConvertResult (EmitContext ec, Binary b)
                        {
                                //
                                // Use original expression for nullable arguments
                                //
                                Nullable.Unwrap unwrap = b.left as Nullable.Unwrap;
                                if (unwrap != null)
                                        b.left = unwrap.Original;

                                unwrap = b.right as Nullable.Unwrap;
                                if (unwrap != null)
                                        b.right = unwrap.Original;

                                b.left = Convert.ImplicitConversion (ec, b.left, left, b.left.Location);
                                b.right = Convert.ImplicitConversion (ec, b.right, right, b.right.Location);

                                //
                                // Start a new concat expression using converted expression
                                //
                                return new StringConcat (ec, b.loc, b.left, b.right).Resolve (ec);
                        }
                }

                class PredefinedShiftOperator : PredefinedOperator {
                        public PredefinedShiftOperator (Type ltype, Operator op_mask) :
                                base (ltype, TypeManager.int32_type, op_mask)
                        {
                        }

                        public override Expression ConvertResult (EmitContext ec, Binary b)
                        {
                                b.left = Convert.ImplicitConversion (ec, b.left, left, b.left.Location);

                                Expression expr_tree_expr = EmptyCast.Create (b.right, TypeManager.int32_type);

                                int right_mask = left == TypeManager.int32_type || left == TypeManager.uint32_type ? 0x1f : 0x3f;

                                //
                                // b = b.left >> b.right & (0x1f|0x3f)
                                //
                                b.right = new Binary (Operator.BitwiseAnd,
                                        b.right, new IntConstant (right_mask, b.right.Location)).Resolve (ec);

                                //
                                // Expression tree representation does not use & mask
                                //
                                b.right = ReducedExpression.Create (b.right, expr_tree_expr).Resolve (ec);
                                b.type = ReturnType;
                                return b;
                        }
                }

                class PredefinedPointerOperator : PredefinedOperator {
                        public PredefinedPointerOperator (Type ltype, Type rtype, Operator op_mask)
                                : base (ltype, rtype, op_mask)
                        {
                        }

                        public PredefinedPointerOperator (Type ltype, Type rtype, Operator op_mask, Type retType)
                                : base (ltype, rtype, op_mask, retType)
                        {
                        }

                        public PredefinedPointerOperator (Type type, Operator op_mask, Type return_type)
                                : base (type, op_mask, return_type)
                        {
                        }

                        public override bool IsApplicable (EmitContext ec, Expression lexpr, Expression rexpr)
                        {
                                if (left == null) {
                                        if (!lexpr.Type.IsPointer)
                                                return false;
                                } else {
                                        if (!Convert.ImplicitConversionExists (ec, lexpr, left))
                                                return false;
                                }

                                if (right == null) {
                                        if (!rexpr.Type.IsPointer)
                                                return false;
                                } else {
                                        if (!Convert.ImplicitConversionExists (ec, rexpr, right))
                                                return false;
                                }

                                return true;
                        }

                        public override Expression ConvertResult (EmitContext ec, Binary b)
                        {
                                if (left != null) {
                                        b.left = EmptyCast.Create (b.left, left);
                                } else if (right != null) {
                                        b.right = EmptyCast.Create (b.right, right);
                                }

                                Type r_type = ReturnType;
                                Expression left_arg, right_arg;
                                if (r_type == null) {
                                        if (left == null) {
                                                left_arg = b.left;
                                                right_arg = b.right;
                                                r_type = b.left.Type;
                                        } else {
                                                left_arg = b.right;
                                                right_arg = b.left;
                                                r_type = b.right.Type;
                                        }
                                } else {
                                        left_arg = b.left;
                                        right_arg = b.right;
                                }

                                return new PointerArithmetic (b.oper, left_arg, right_arg, r_type, b.loc).Resolve (ec);
                        }
                }

                [Flags]
                public enum Operator {
                        Multiply        = 0 | ArithmeticMask,
                        Division        = 1 | ArithmeticMask,
                        Modulus         = 2 | ArithmeticMask,
                        Addition        = 3 | ArithmeticMask | AdditionMask,
                        Subtraction = 4 | ArithmeticMask | SubtractionMask,

                        LeftShift       = 5 | ShiftMask,
                        RightShift      = 6 | ShiftMask,

                        LessThan        = 7 | ComparisonMask | RelationalMask,
                        GreaterThan     = 8 | ComparisonMask | RelationalMask,
                        LessThanOrEqual         = 9 | ComparisonMask | RelationalMask,
                        GreaterThanOrEqual      = 10 | ComparisonMask | RelationalMask,
                        Equality        = 11 | ComparisonMask | EqualityMask,
                        Inequality      = 12 | ComparisonMask | EqualityMask,

                        BitwiseAnd      = 13 | BitwiseMask,
                        ExclusiveOr     = 14 | BitwiseMask,
                        BitwiseOr       = 15 | BitwiseMask,

                        LogicalAnd      = 16 | LogicalMask,
                        LogicalOr       = 17 | LogicalMask,

                        //
                        // Operator masks
                        //
                        ValuesOnlyMask  = ArithmeticMask - 1,
                        ArithmeticMask  = 1 << 5,
                        ShiftMask               = 1 << 6,
                        ComparisonMask  = 1 << 7,
                        EqualityMask    = 1 << 8,
                        BitwiseMask             = 1 << 9,
                        LogicalMask             = 1 << 10,
                        AdditionMask    = 1 << 11,
                        SubtractionMask = 1 << 12,
                        RelationalMask  = 1 << 13
                }

                readonly Operator oper;
                protected Expression left, right;
                readonly bool is_compound;
                Expression enum_conversion;

                static PredefinedOperator [] standard_operators;
                static PredefinedOperator [] pointer_operators;
                
                public Binary (Operator oper, Expression left, Expression right, bool isCompound)
                        : this (oper, left, right)
                {
                        this.is_compound = isCompound;
                }

                public Binary (Operator oper, Expression left, Expression right)
                {
                        this.oper = oper;
                        this.left = left;
                        this.right = right;
                        this.loc = left.Location;
                }

                public Operator Oper {
                        get {
                                return oper;
                        }
                }
                
                /// <summary>
                ///   Returns a stringified representation of the Operator
                /// </summary>
                string OperName (Operator oper)
                {
                        string s;
                        switch (oper){
                        case Operator.Multiply:
                                s = "*";
                                break;
                        case Operator.Division:
                                s = "/";
                                break;
                        case Operator.Modulus:
                                s = "%";
                                break;
                        case Operator.Addition:
                                s = "+";
                                break;
                        case Operator.Subtraction:
                                s = "-";
                                break;
                        case Operator.LeftShift:
                                s = "<<";
                                break;
                        case Operator.RightShift:
                                s = ">>";
                                break;
                        case Operator.LessThan:
                                s = "<";
                                break;
                        case Operator.GreaterThan:
                                s = ">";
                                break;
                        case Operator.LessThanOrEqual:
                                s = "<=";
                                break;
                        case Operator.GreaterThanOrEqual:
                                s = ">=";
                                break;
                        case Operator.Equality:
                                s = "==";
                                break;
                        case Operator.Inequality:
                                s = "!=";
                                break;
                        case Operator.BitwiseAnd:
                                s = "&";
                                break;
                        case Operator.BitwiseOr:
                                s = "|";
                                break;
                        case Operator.ExclusiveOr:
                                s = "^";
                                break;
                        case Operator.LogicalOr:
                                s = "||";
                                break;
                        case Operator.LogicalAnd:
                                s = "&&";
                                break;
                        default:
                                s = oper.ToString ();
                                break;
                        }

                        if (is_compound)
                                return s + "=";

                        return s;
                }

                public static void Error_OperatorCannotBeApplied (Expression left, Expression right, Operator oper, Location loc)
                {
                        new Binary (oper, left, right).Error_OperatorCannotBeApplied (left, right);
                }

                public static void Error_OperatorCannotBeApplied (Expression left, Expression right, string oper, Location loc)
                {
                        string l, r;
                        l = TypeManager.CSharpName (left.Type);
                        r = TypeManager.CSharpName (right.Type);

                        Report.Error (19, loc, "Operator `{0}' cannot be applied to operands of type `{1}' and `{2}'",
                                oper, l, r);
                }
                
                protected void Error_OperatorCannotBeApplied (Expression left, Expression right)
                {
                        Error_OperatorCannotBeApplied (left, right, OperName (oper), loc);
                }

                static string GetOperatorMetadataName (Operator op)
                {
                        CSharp.Operator.OpType op_type;
                        switch (op) {
                        case Operator.Addition:
                                op_type = CSharp.Operator.OpType.Addition; break;
                        case Operator.BitwiseAnd:
                                op_type = CSharp.Operator.OpType.BitwiseAnd; break;
                        case Operator.BitwiseOr:
                                op_type = CSharp.Operator.OpType.BitwiseOr; break;
                        case Operator.Division:
                                op_type = CSharp.Operator.OpType.Division; break;
                        case Operator.Equality:
                                op_type = CSharp.Operator.OpType.Equality; break;
                        case Operator.ExclusiveOr:
                                op_type = CSharp.Operator.OpType.ExclusiveOr; break;
                        case Operator.GreaterThan:
                                op_type = CSharp.Operator.OpType.GreaterThan; break;
                        case Operator.GreaterThanOrEqual:
                                op_type = CSharp.Operator.OpType.GreaterThanOrEqual; break;
                        case Operator.Inequality:
                                op_type = CSharp.Operator.OpType.Inequality; break;
                        case Operator.LeftShift:
                                op_type = CSharp.Operator.OpType.LeftShift; break;
                        case Operator.LessThan:
                                op_type = CSharp.Operator.OpType.LessThan; break;
                        case Operator.LessThanOrEqual:
                                op_type = CSharp.Operator.OpType.LessThanOrEqual; break;
                        case Operator.Modulus:
                                op_type = CSharp.Operator.OpType.Modulus; break;
                        case Operator.Multiply:
                                op_type = CSharp.Operator.OpType.Multiply; break;
                        case Operator.RightShift:
                                op_type = CSharp.Operator.OpType.RightShift; break;
                        case Operator.Subtraction:
                                op_type = CSharp.Operator.OpType.Subtraction; break;
                        default:
                                throw new InternalErrorException (op.ToString ());
                        }

                        return CSharp.Operator.GetMetadataName (op_type);
                }

                public static void EmitOperatorOpcode (EmitContext ec, Operator oper, Type l)
                {
                        OpCode opcode;
                        ILGenerator ig = ec.ig;

                        switch (oper){
                        case Operator.Multiply:
                                if (ec.CheckState){
                                        if (l == TypeManager.int32_type || l == TypeManager.int64_type)
                                                opcode = OpCodes.Mul_Ovf;
                                        else if (!IsFloat (l))
                                                opcode = OpCodes.Mul_Ovf_Un;
                                        else
                                                opcode = OpCodes.Mul;
                                } else
                                        opcode = OpCodes.Mul;
                                
                                break;
                                
                        case Operator.Division:
                                if (IsUnsigned (l))
                                        opcode = OpCodes.Div_Un;
                                else
                                        opcode = OpCodes.Div;
                                break;
                                
                        case Operator.Modulus:
                                if (IsUnsigned (l))
                                        opcode = OpCodes.Rem_Un;
                                else
                                        opcode = OpCodes.Rem;
                                break;

                        case Operator.Addition:
                                if (ec.CheckState){
                                        if (l == TypeManager.int32_type || l == TypeManager.int64_type)
                                                opcode = OpCodes.Add_Ovf;
                                        else if (!IsFloat (l))
                                                opcode = OpCodes.Add_Ovf_Un;
                                        else
                                                opcode = OpCodes.Add;
                                } else
                                        opcode = OpCodes.Add;
                                break;

                        case Operator.Subtraction:
                                if (ec.CheckState){
                                        if (l == TypeManager.int32_type || l == TypeManager.int64_type)
                                                opcode = OpCodes.Sub_Ovf;
                                        else if (!IsFloat (l))
                                                opcode = OpCodes.Sub_Ovf_Un;
                                        else
                                                opcode = OpCodes.Sub;
                                } else
                                        opcode = OpCodes.Sub;
                                break;

                        case Operator.RightShift:
                                if (IsUnsigned (l))
                                        opcode = OpCodes.Shr_Un;
                                else
                                        opcode = OpCodes.Shr;
                                break;
                                
                        case Operator.LeftShift:
                                opcode = OpCodes.Shl;
                                break;

                        case Operator.Equality:
                                opcode = OpCodes.Ceq;
                                break;

                        case Operator.Inequality:
                                ig.Emit (OpCodes.Ceq);
                                ig.Emit (OpCodes.Ldc_I4_0);
                                
                                opcode = OpCodes.Ceq;
                                break;

                        case Operator.LessThan:
                                if (IsUnsigned (l))
                                        opcode = OpCodes.Clt_Un;
                                else
                                        opcode = OpCodes.Clt;
                                break;

                        case Operator.GreaterThan:
                                if (IsUnsigned (l))
                                        opcode = OpCodes.Cgt_Un;
                                else
                                        opcode = OpCodes.Cgt;
                                break;

                        case Operator.LessThanOrEqual:
                                if (IsUnsigned (l) || IsFloat (l))
                                        ig.Emit (OpCodes.Cgt_Un);
                                else
                                        ig.Emit (OpCodes.Cgt);
                                ig.Emit (OpCodes.Ldc_I4_0);
                                
                                opcode = OpCodes.Ceq;
                                break;

                        case Operator.GreaterThanOrEqual:
                                if (IsUnsigned (l) || IsFloat (l))
                                        ig.Emit (OpCodes.Clt_Un);
                                else
                                        ig.Emit (OpCodes.Clt);
                                
                                ig.Emit (OpCodes.Ldc_I4_0);
                                
                                opcode = OpCodes.Ceq;
                                break;

                        case Operator.BitwiseOr:
                                opcode = OpCodes.Or;
                                break;

                        case Operator.BitwiseAnd:
                                opcode = OpCodes.And;
                                break;

                        case Operator.ExclusiveOr:
                                opcode = OpCodes.Xor;
                                break;

                        default:
                                throw new InternalErrorException (oper.ToString ());
                        }

                        ig.Emit (opcode);
                }

                static bool IsUnsigned (Type t)
                {
                        if (t.IsPointer)
                                return true;

                        return (t == TypeManager.uint32_type || t == TypeManager.uint64_type ||
                                t == TypeManager.ushort_type || t == TypeManager.byte_type);
                }

                static bool IsFloat (Type t)
                {
                        return t == TypeManager.float_type || t == TypeManager.double_type;
                }

                Expression ResolveOperator (EmitContext ec)
                {
                        Type l = left.Type;
                        Type r = right.Type;
                        Expression expr;
                        bool primitives_only = false;

                        if (standard_operators == null)
                                CreateStandardOperatorsTable ();

                        //
                        // Handles predefined primitive types
                        //
                        if (TypeManager.IsPrimitiveType (l) && TypeManager.IsPrimitiveType (r)) {
                                if ((oper & Operator.ShiftMask) == 0) {
                                        if (l != TypeManager.bool_type && !DoBinaryOperatorPromotion (ec))
                                                return null;

                                        primitives_only = true;
                                }
                        } else {
                                // Pointers
                                if (l.IsPointer || r.IsPointer)
                                        return ResolveOperatorPointer (ec, l, r);

                                // Enums
                                bool lenum = TypeManager.IsEnumType (l);
                                bool renum = TypeManager.IsEnumType (r);
                                if (lenum || renum) {
                                        expr = ResolveOperatorEnum (ec, lenum, renum, l, r);

                                        // TODO: Can this be ambiguous
                                        if (expr != null)
                                                return expr;
                                }

                                // Delegates
                                if ((oper == Operator.Addition || oper == Operator.Subtraction || (oper & Operator.EqualityMask) != 0) &&
                                         (TypeManager.IsDelegateType (l) || TypeManager.IsDelegateType (r))) {
                                                
                                        expr = ResolveOperatorDelegate (ec, l, r);

                                        // TODO: Can this be ambiguous
                                        if (expr != null)
                                                return expr;
                                }

                                // User operators
                                expr = ResolveUserOperator (ec, l, r);
                                if (expr != null)
                                        return expr;

                                // Predefined reference types equality
                                if ((oper & Operator.EqualityMask) != 0) {
                                        expr = ResolveOperatorEqualityRerefence (ec, l, r);
                                        if (expr != null)
                                                return expr;
                                }
                        }

                        return ResolveOperatorPredefined (ec, standard_operators, primitives_only, null);
                }

                // at least one of 'left' or 'right' is an enumeration constant (EnumConstant or SideEffectConstant or ...)
                // if 'left' is not an enumeration constant, create one from the type of 'right'
                Constant EnumLiftUp (EmitContext ec, Constant left, Constant right, Location loc)
                {
                        switch (oper) {
                        case Operator.BitwiseOr:
                        case Operator.BitwiseAnd:
                        case Operator.ExclusiveOr:
                        case Operator.Equality:
                        case Operator.Inequality:
                        case Operator.LessThan:
                        case Operator.LessThanOrEqual:
                        case Operator.GreaterThan:
                        case Operator.GreaterThanOrEqual:
                                if (TypeManager.IsEnumType (left.Type))
                                        return left;
                                
                                if (left.IsZeroInteger)
                                        return left.TryReduce (ec, right.Type, loc);
                                
                                break;
                                
                        case Operator.Addition:
                        case Operator.Subtraction:
                                return left;
                                
                        case Operator.Multiply:
                        case Operator.Division:
                        case Operator.Modulus:
                        case Operator.LeftShift:
                        case Operator.RightShift:
                                if (TypeManager.IsEnumType (right.Type) || TypeManager.IsEnumType (left.Type))
                                        break;
                                return left;
                        }
                        Error_OperatorCannotBeApplied (this.left, this.right);
                        return null;
                }

                //
                // The `|' operator used on types which were extended is dangerous
                //
                void CheckBitwiseOrOnSignExtended ()
                {
                        OpcodeCast lcast = left as OpcodeCast;
                        if (lcast != null) {
                                if (IsUnsigned (lcast.UnderlyingType))
                                        lcast = null;
                        }

                        OpcodeCast rcast = right as OpcodeCast;
                        if (rcast != null) {
                                if (IsUnsigned (rcast.UnderlyingType))
                                        rcast = null;
                        }

                        if (lcast == null && rcast == null)
                                return;

                        // FIXME: consider constants

                        Report.Warning (675, 3, loc,
                                "The operator `|' used on the sign-extended type `{0}'. Consider casting to a smaller unsigned type first",
                                TypeManager.CSharpName (lcast != null ? lcast.UnderlyingType : rcast.UnderlyingType));
                }

                static void CreatePointerOperatorsTable ()
                {
                        ArrayList temp = new ArrayList ();

                        //
                        // Pointer arithmetic:
                        //
                        // T* operator + (T* x, int y);         T* operator - (T* x, int y);
                        // T* operator + (T* x, uint y);        T* operator - (T* x, uint y);
                        // T* operator + (T* x, long y);        T* operator - (T* x, long y);
                        // T* operator + (T* x, ulong y);       T* operator - (T* x, ulong y);
                        //
                        temp.Add (new PredefinedPointerOperator (null, TypeManager.int32_type, Operator.AdditionMask | Operator.SubtractionMask));
                        temp.Add (new PredefinedPointerOperator (null, TypeManager.uint32_type, Operator.AdditionMask | Operator.SubtractionMask));
                        temp.Add (new PredefinedPointerOperator (null, TypeManager.int64_type, Operator.AdditionMask | Operator.SubtractionMask));
                        temp.Add (new PredefinedPointerOperator (null, TypeManager.uint64_type, Operator.AdditionMask | Operator.SubtractionMask));

                        //
                        // T* operator + (int y,   T* x);
                        // T* operator + (uint y,  T *x);
                        // T* operator + (long y,  T *x);
                        // T* operator + (ulong y, T *x);
                        //
                        temp.Add (new PredefinedPointerOperator (TypeManager.int32_type, null, Operator.AdditionMask, null));
                        temp.Add (new PredefinedPointerOperator (TypeManager.uint32_type, null, Operator.AdditionMask, null));
                        temp.Add (new PredefinedPointerOperator (TypeManager.int64_type, null, Operator.AdditionMask, null));
                        temp.Add (new PredefinedPointerOperator (TypeManager.uint64_type, null, Operator.AdditionMask, null));

                        //
                        // long operator - (T* x, T *y)
                        //
                        temp.Add (new PredefinedPointerOperator (null, Operator.SubtractionMask, TypeManager.int64_type));

                        pointer_operators = (PredefinedOperator []) temp.ToArray (typeof (PredefinedOperator));
                }

                static void CreateStandardOperatorsTable ()
                {
                        ArrayList temp = new ArrayList ();
                        Type bool_type = TypeManager.bool_type;

                        temp.Add (new PredefinedOperator (TypeManager.int32_type, Operator.ArithmeticMask | Operator.BitwiseMask));
                        temp.Add (new PredefinedOperator (TypeManager.uint32_type, Operator.ArithmeticMask | Operator.BitwiseMask));
                        temp.Add (new PredefinedOperator (TypeManager.int64_type, Operator.ArithmeticMask | Operator.BitwiseMask));
                        temp.Add (new PredefinedOperator (TypeManager.uint64_type, Operator.ArithmeticMask | Operator.BitwiseMask));
                        temp.Add (new PredefinedOperator (TypeManager.float_type, Operator.ArithmeticMask));
                        temp.Add (new PredefinedOperator (TypeManager.double_type, Operator.ArithmeticMask));
                        temp.Add (new PredefinedOperator (TypeManager.decimal_type, Operator.ArithmeticMask));

                        temp.Add (new PredefinedOperator (TypeManager.int32_type, Operator.ComparisonMask, bool_type));
                        temp.Add (new PredefinedOperator (TypeManager.uint32_type, Operator.ComparisonMask, bool_type));
                        temp.Add (new PredefinedOperator (TypeManager.int64_type, Operator.ComparisonMask, bool_type));
                        temp.Add (new PredefinedOperator (TypeManager.uint64_type, Operator.ComparisonMask, bool_type));
                        temp.Add (new PredefinedOperator (TypeManager.float_type, Operator.ComparisonMask, bool_type));
                        temp.Add (new PredefinedOperator (TypeManager.double_type, Operator.ComparisonMask, bool_type));
                        temp.Add (new PredefinedOperator (TypeManager.decimal_type, Operator.ComparisonMask, bool_type));

                        temp.Add (new PredefinedOperator (TypeManager.string_type, Operator.EqualityMask, bool_type));

                        temp.Add (new PredefinedStringOperator (TypeManager.string_type, Operator.AdditionMask));
                        temp.Add (new PredefinedStringOperator (TypeManager.string_type, TypeManager.object_type, Operator.AdditionMask));
                        temp.Add (new PredefinedStringOperator (TypeManager.object_type, TypeManager.string_type, Operator.AdditionMask));

                        temp.Add (new PredefinedOperator (bool_type,
                                Operator.BitwiseMask | Operator.LogicalMask | Operator.EqualityMask, bool_type));

                        temp.Add (new PredefinedShiftOperator (TypeManager.int32_type, Operator.ShiftMask));
                        temp.Add (new PredefinedShiftOperator (TypeManager.uint32_type, Operator.ShiftMask));
                        temp.Add (new PredefinedShiftOperator (TypeManager.int64_type, Operator.ShiftMask));
                        temp.Add (new PredefinedShiftOperator (TypeManager.uint64_type, Operator.ShiftMask));

                        standard_operators = (PredefinedOperator []) temp.ToArray (typeof (PredefinedOperator));
                }

                //
                // Rules used during binary numeric promotion
                //
                static bool DoNumericPromotion (ref Expression prim_expr, ref Expression second_expr, Type type)
                {
                        Expression temp;
                        Type etype;

                        Constant c = prim_expr as Constant;
                        if (c != null) {
                                temp = c.ConvertImplicitly (type);
                                if (temp != null) {
                                        prim_expr = temp;
                                        return true;
                                }
                        }

                        if (type == TypeManager.uint32_type) {
                                etype = prim_expr.Type;
                                if (etype == TypeManager.int32_type || etype == TypeManager.short_type || etype == TypeManager.sbyte_type) {
                                        type = TypeManager.int64_type;

                                        if (type != second_expr.Type) {
                                                c = second_expr as Constant;
                                                if (c != null)
                                                        temp = c.ConvertImplicitly (type);
                                                else
                                                        temp = Convert.ImplicitNumericConversion (second_expr, type);
                                                if (temp == null)
                                                        return false;
                                                second_expr = temp;
                                        }
                                }
                        } else if (type == TypeManager.uint64_type) {
                                //
                                // A compile-time error occurs if the other operand is of type sbyte, short, int, or long
                                //
                                if (type == TypeManager.int32_type || type == TypeManager.int64_type ||
                                        type == TypeManager.sbyte_type || type == TypeManager.sbyte_type)
                                        return false;
                        }

                        temp = Convert.ImplicitNumericConversion (prim_expr, type);
                        if (temp == null)
                                return false;

                        prim_expr = temp;
                        return true;
                }

                //
                // 7.2.6.2 Binary numeric promotions
                //
                public bool DoBinaryOperatorPromotion (EmitContext ec)
                {
                        Type ltype = left.Type;
                        Type rtype = right.Type;
                        Expression temp;

                        foreach (Type t in ConstantFold.binary_promotions) {
                                if (t == ltype)
                                        return t == rtype || DoNumericPromotion (ref right, ref left, t);

                                if (t == rtype)
                                        return t == ltype || DoNumericPromotion (ref left, ref right, t);
                        }

                        Type int32 = TypeManager.int32_type;
                        if (ltype != int32) {
                                Constant c = left as Constant;
                                if (c != null)
                                        temp = c.ConvertImplicitly (int32);
                                else
                                        temp = Convert.ImplicitNumericConversion (left, int32);

                                if (temp == null)
                                        return false;
                                left = temp;
                        }

                        if (rtype != int32) {
                                Constant c = right as Constant;
                                if (c != null)
                                        temp = c.ConvertImplicitly (int32);
                                else
                                        temp = Convert.ImplicitNumericConversion (right, int32);

                                if (temp == null)
                                        return false;
                                right = temp;
                        }

                        return true;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (left == null)
                                return null;

                        if ((oper == Operator.Subtraction) && (left is ParenthesizedExpression)) {
                                left = ((ParenthesizedExpression) left).Expr;
                                left = left.Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.Type);
                                if (left == null)
                                        return null;

                                if (left.eclass == ExprClass.Type) {
                                        Report.Error (75, loc, "To cast a negative value, you must enclose the value in parentheses");
                                        return null;
                                }
                        } else
                                left = left.Resolve (ec);

                        if (left == null)
                                return null;

                        Constant lc = left as Constant;

                        if (lc != null && lc.Type == TypeManager.bool_type &&
                                ((oper == Operator.LogicalAnd && lc.IsDefaultValue) ||
                                 (oper == Operator.LogicalOr && !lc.IsDefaultValue))) {

                                // FIXME: resolve right expression as unreachable
                                // right.Resolve (ec);

                                Report.Warning (429, 4, loc, "Unreachable expression code detected");
                                return left;
                        }

                        right = right.Resolve (ec);
                        if (right == null)
                                return null;

                        eclass = ExprClass.Value;
                        Constant rc = right as Constant;

                        // The conversion rules are ignored in enum context but why
                        if (!ec.InEnumContext && lc != null && rc != null && (TypeManager.IsEnumType (left.Type) || TypeManager.IsEnumType (right.Type))) {
                                lc = EnumLiftUp (ec, lc, rc, loc);
                                if (lc != null)
                                        rc = EnumLiftUp (ec, rc, lc, loc);
                        }

                        if (rc != null && lc != null) {
                                int prev_e = Report.Errors;
                                Expression e = ConstantFold.BinaryFold (
                                        ec, oper, lc, rc, loc);
                                if (e != null || Report.Errors != prev_e)
                                        return e;
                        } else {
                                if ((oper == Operator.BitwiseAnd || oper == Operator.LogicalAnd) &&
                                        ((lc != null && lc.IsDefaultValue) || (rc != null && rc.IsDefaultValue))) {

                                        if ((ResolveOperator (ec)) == null) {
                                                Error_OperatorCannotBeApplied (left, right);
                                                return null;
                                        }

                                        //
                                        // The result is a constant with side-effect
                                        //
                                        Constant side_effect = rc == null ?
                                                new SideEffectConstant (lc, right, loc) :
                                                new SideEffectConstant (rc, left, loc);

                                        return ReducedExpression.Create (side_effect, this);
                                }
                        }

                        // Comparison warnings
                        if ((oper & Operator.ComparisonMask) != 0) {
                                if (left.Equals (right)) {
                                        Report.Warning (1718, 3, loc, "A comparison made to same variable. Did you mean to compare something else?");
                                }
                                CheckUselessComparison (lc, right.Type);
                                CheckUselessComparison (rc, left.Type);
                        }

                        if (RootContext.Version >= LanguageVersion.ISO_2 &&
                                ((TypeManager.IsNullableType (left.Type) && (right is NullLiteral || TypeManager.IsNullableType (right.Type) || TypeManager.IsValueType (right.Type))) ||
                                (TypeManager.IsValueType (left.Type) && right is NullLiteral) ||
                                (TypeManager.IsNullableType (right.Type) && (left is NullLiteral || TypeManager.IsNullableType (left.Type) || TypeManager.IsValueType (left.Type))) ||
                                (TypeManager.IsValueType (right.Type) && left is NullLiteral)))
                                return new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);

                        return DoResolveCore (ec, left, right);
                }

                protected Expression DoResolveCore (EmitContext ec, Expression left_orig, Expression right_orig)
                {
                        Expression expr = ResolveOperator (ec);
                        if (expr == null)
                                Error_OperatorCannotBeApplied (left_orig, right_orig);

                        if (left == null || right == null)
                                throw new InternalErrorException ("Invalid conversion");

                        if (oper == Operator.BitwiseOr)
                                CheckBitwiseOrOnSignExtended ();

                        return expr;
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        left.MutateHoistedGenericType (storey);
                        right.MutateHoistedGenericType (storey);
                }

                //
                // D operator + (D x, D y)
                // D operator - (D x, D y)
                // bool operator == (D x, D y)
                // bool operator != (D x, D y)
                //
                Expression ResolveOperatorDelegate (EmitContext ec, Type l, Type r)
                {
                        bool is_equality = (oper & Operator.EqualityMask) != 0;
                        if (!TypeManager.IsEqual (l, r)) {
                                Expression tmp;
                                if (right.eclass == ExprClass.MethodGroup || (r == TypeManager.anonymous_method_type && !is_equality)) {
                                        tmp = Convert.ImplicitConversionRequired (ec, right, l, loc);
                                        if (tmp == null)
                                                return null;
                                        right = tmp;
                                        r = right.Type;
                                } else if (left.eclass == ExprClass.MethodGroup || (l == TypeManager.anonymous_method_type && !is_equality)) {
                                        tmp = Convert.ImplicitConversionRequired (ec, left, r, loc);
                                        if (tmp == null)
                                                return null;
                                        left = tmp;
                                        l = left.Type;
                                } else {
                                        return null;
                                }
                        }

                        //
                        // Resolve delegate equality as a user operator
                        //
                        if (is_equality)
                                return ResolveUserOperator (ec, l, r);

                        MethodInfo method;
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (left, Argument.AType.Expression));
                        args.Add (new Argument (right, Argument.AType.Expression));

                        if (oper == Operator.Addition) {
                                if (TypeManager.delegate_combine_delegate_delegate == null) {
                                        TypeManager.delegate_combine_delegate_delegate = TypeManager.GetPredefinedMethod (
                                                TypeManager.delegate_type, "Combine", loc, TypeManager.delegate_type, TypeManager.delegate_type);
                                }

                                method = TypeManager.delegate_combine_delegate_delegate;
                        } else {
                                if (TypeManager.delegate_remove_delegate_delegate == null) {
                                        TypeManager.delegate_remove_delegate_delegate = TypeManager.GetPredefinedMethod (
                                                TypeManager.delegate_type, "Remove", loc, TypeManager.delegate_type, TypeManager.delegate_type);
                                }

                                method = TypeManager.delegate_remove_delegate_delegate;
                        }

                        MethodGroupExpr mg = new MethodGroupExpr (new MemberInfo [] { method }, TypeManager.delegate_type, loc);
                        mg = mg.OverloadResolve (ec, ref args, false, loc);

                        return new ClassCast (new UserOperatorCall (mg, args, CreateExpressionTree, loc), l);
                }

                //
                // Enumeration operators
                //
                Expression ResolveOperatorEnum (EmitContext ec, bool lenum, bool renum, Type ltype, Type rtype)
                {
                        //
                        // bool operator == (E x, E y);
                        // bool operator != (E x, E y);
                        // bool operator < (E x, E y);
                        // bool operator > (E x, E y);
                        // bool operator <= (E x, E y);
                        // bool operator >= (E x, E y);
                        //
                        // E operator & (E x, E y);
                        // E operator | (E x, E y);
                        // E operator ^ (E x, E y);
                        //
                        // U operator - (E e, E f)
                        // E operator - (E e, U x)
                        //
                        // E operator + (U x, E e)
                        // E operator + (E e, U x)
                        //
                        if (!((oper & (Operator.ComparisonMask | Operator.BitwiseMask)) != 0 ||
                                (oper == Operator.Subtraction && lenum) || (oper == Operator.Addition && lenum != renum)))
                                return null;

                        Expression ltemp = left;
                        Expression rtemp = right;
                        Type underlying_type;
                        Expression expr;
                        
                        if ((oper & Operator.ComparisonMask | Operator.BitwiseMask) != 0) {
                                if (renum) {
                                        expr = Convert.ImplicitConversion (ec, left, rtype, loc);
                                        if (expr != null) {
                                                left = expr;
                                                ltype = expr.Type;
                                        }
                                } else if (lenum) {
                                        expr = Convert.ImplicitConversion (ec, right, ltype, loc);
                                        if (expr != null) {
                                                right = expr;
                                                rtype = expr.Type;
                                        }
                                }
                        }                       

                        if (TypeManager.IsEqual (ltype, rtype)) {
                                underlying_type = TypeManager.GetEnumUnderlyingType (ltype);

                                if (left is Constant)
                                        left = ((Constant) left).ConvertExplicitly (false, underlying_type);
                                else
                                        left = EmptyCast.Create (left, underlying_type);

                                if (right is Constant)
                                        right = ((Constant) right).ConvertExplicitly (false, underlying_type);
                                else
                                        right = EmptyCast.Create (right, underlying_type);
                        } else if (lenum) {
                                underlying_type = TypeManager.GetEnumUnderlyingType (ltype);

                                if (oper != Operator.Subtraction && oper != Operator.Addition) {
                                        Constant c = right as Constant;
                                        if (c == null || !c.IsDefaultValue)
                                                return null;
                                } else {
                                        if (!Convert.ImplicitStandardConversionExists (right, underlying_type))
                                                return null;

                                        right = Convert.ImplicitConversionStandard (ec, right, underlying_type, right.Location);
                                }

                                if (left is Constant)
                                        left = ((Constant) left).ConvertExplicitly (false, underlying_type);
                                else
                                        left = EmptyCast.Create (left, underlying_type);

                        } else if (renum) {
                                underlying_type = TypeManager.GetEnumUnderlyingType (rtype);

                                if (oper != Operator.Addition) {
                                        Constant c = left as Constant;
                                        if (c == null || !c.IsDefaultValue)
                                                return null;
                                } else {
                                        if (!Convert.ImplicitStandardConversionExists (left, underlying_type))
                                                return null;

                                        left = Convert.ImplicitConversionStandard (ec, left, underlying_type, left.Location);
                                }

                                if (right is Constant)
                                        right = ((Constant) right).ConvertExplicitly (false, underlying_type);
                                else
                                        right = EmptyCast.Create (right, underlying_type);

                        } else {
                                return null;
                        }

                        //
                        // C# specification uses explicit cast syntax which means binary promotion
                        // should happen, however it seems that csc does not do that
                        //
                        if (!DoBinaryOperatorPromotion (ec)) {
                                left = ltemp;
                                right = rtemp;
                                return null;
                        }

                        Type res_type = null;
                        if ((oper & Operator.BitwiseMask) != 0 || oper == Operator.Subtraction || oper == Operator.Addition) {
                                Type promoted_type = lenum ? left.Type : right.Type;
                                enum_conversion = Convert.ExplicitNumericConversion (
                                        new EmptyExpression (promoted_type), underlying_type);

                                if (oper == Operator.Subtraction && renum && lenum)
                                        res_type = underlying_type;
                                else if (oper == Operator.Addition && renum)
                                        res_type = rtype;
                                else
                                        res_type = ltype;
                        }
                        
                        expr = ResolveOperatorPredefined (ec, standard_operators, true, res_type);
                        if (!is_compound || expr == null)
                                return expr;

                        //
                        // TODO: Need to corectly implemented Coumpound Assigment for all operators
                        // Section: 7.16.2
                        //
                        if (Convert.ImplicitConversionExists (ec, left, rtype))
                                return expr;

                        if (!Convert.ImplicitConversionExists (ec, ltemp, rtype))
                                return null;

                        expr = Convert.ExplicitConversion (ec, expr, rtype, loc);
                        return expr;
                }

                //
                // 7.9.6 Reference type equality operators
                //
                Binary ResolveOperatorEqualityRerefence (EmitContext ec, Type l, Type r)
                {
                        //
                        // operator != (object a, object b)
                        // operator == (object a, object b)
                        //

                        // TODO: this method is almost equivalent to Convert.ImplicitReferenceConversion

                        if (left.eclass == ExprClass.MethodGroup || right.eclass == ExprClass.MethodGroup)
                                return null;

                        type = TypeManager.bool_type;
                        GenericConstraints constraints;

                        bool lgen = TypeManager.IsGenericParameter (l);

                        if (TypeManager.IsEqual (l, r)) {
                                if (lgen) {
                                        //
                                        // Only allow to compare same reference type parameter
                                        //
                                        constraints = TypeManager.GetTypeParameterConstraints (l);
                                        if (constraints != null && constraints.IsReferenceType)
                                                return this;

                                        return null;
                                }

                                if (l == TypeManager.anonymous_method_type)
                                        return null;

                                if (TypeManager.IsValueType (l))
                                        return null;

                                return this;
                        }

                        bool rgen = TypeManager.IsGenericParameter (r);

                        //
                        // a, Both operands are reference-type values or the value null
                        // b, One operand is a value of type T where T is a type-parameter and
                        // the other operand is the value null. Furthermore T does not have the
                        // value type constrain
                        //
                        if (left is NullLiteral || right is NullLiteral) {
                                if (lgen) {
                                        constraints = TypeManager.GetTypeParameterConstraints (l);
                                        if (constraints != null && constraints.HasValueTypeConstraint)
                                                return null;

                                        left = new BoxedCast (left, TypeManager.object_type);
                                        return this;
                                }

                                if (rgen) {
                                        constraints = TypeManager.GetTypeParameterConstraints (r);
                                        if (constraints != null && constraints.HasValueTypeConstraint)
                                                return null;

                                        right = new BoxedCast (right, TypeManager.object_type);
                                        return this;
                                }
                        }

                        //
                        // An interface is converted to the object before the
                        // standard conversion is applied. It's not clear from the
                        // standard but it looks like it works like that.
                        //
                        if (lgen) {
                                constraints = TypeManager.GetTypeParameterConstraints (l);
                                if (constraints == null || constraints.IsReferenceType)
                                        return null;
                        } else if (l.IsInterface) {
                                l = TypeManager.object_type;
                        } else if (TypeManager.IsStruct (l)) {
                                return null;
                        }

                        if (rgen) {
                                constraints = TypeManager.GetTypeParameterConstraints (r);
                                if (constraints == null || constraints.IsReferenceType)
                                        return null;
                        } else if (r.IsInterface) {
                                r = TypeManager.object_type;
                        } else if (TypeManager.IsStruct (r)) {
                                return null;
                        }


                        const string ref_comparison = "Possible unintended reference comparison. " +
                                "Consider casting the {0} side of the expression to `string' to compare the values";

                        //
                        // A standard implicit conversion exists from the type of either
                        // operand to the type of the other operand
                        //
                        if (Convert.ImplicitReferenceConversionExists (left, r)) {
                                if (l == TypeManager.string_type)
                                        Report.Warning (253, 2, loc, ref_comparison, "right");

                                return this;
                        }

                        if (Convert.ImplicitReferenceConversionExists (right, l)) {
                                if (r == TypeManager.string_type)
                                        Report.Warning (252, 2, loc, ref_comparison, "left");

                                return this;
                        }

                        return null;
                }


                Expression ResolveOperatorPointer (EmitContext ec, Type l, Type r)
                {
                        //
                        // bool operator == (void* x, void* y);
                        // bool operator != (void* x, void* y);
                        // bool operator < (void* x, void* y);
                        // bool operator > (void* x, void* y);
                        // bool operator <= (void* x, void* y);
                        // bool operator >= (void* x, void* y);
                        //
                        if ((oper & Operator.ComparisonMask) != 0) {
                                Expression temp;
                                if (!l.IsPointer) {
                                        temp = Convert.ImplicitConversion (ec, left, r, left.Location);
                                        if (temp == null)
                                                return null;
                                        left = temp;
                                }

                                if (!r.IsPointer) {
                                        temp = Convert.ImplicitConversion (ec, right, l, right.Location);
                                        if (temp == null)
                                                return null;
                                        right = temp;
                                }

                                type = TypeManager.bool_type;
                                return this;
                        }

                        if (pointer_operators == null)
                                CreatePointerOperatorsTable ();

                        return ResolveOperatorPredefined (ec, pointer_operators, false, null);
                }

                //
                // Build-in operators method overloading
                //
                protected virtual Expression ResolveOperatorPredefined (EmitContext ec, PredefinedOperator [] operators, bool primitives_only, Type enum_type)
                {
                        PredefinedOperator best_operator = null;
                        Type l = left.Type;
                        Type r = right.Type;
                        Operator oper_mask = oper & ~Operator.ValuesOnlyMask;

                        foreach (PredefinedOperator po in operators) {
                                if ((po.OperatorsMask & oper_mask) == 0)
                                        continue;

                                if (primitives_only) {
                                        if (!po.IsPrimitiveApplicable (l, r))
                                                continue;
                                } else {
                                        if (!po.IsApplicable (ec, left, right))
                                                continue;
                                }

                                if (best_operator == null) {
                                        best_operator = po;
                                        if (primitives_only)
                                                break;

                                        continue;
                                }

                                best_operator = po.ResolveBetterOperator (ec, best_operator);

                                if (best_operator == null) {
                                        Report.Error (34, loc, "Operator `{0}' is ambiguous on operands of type `{1}' and `{2}'",
                                                OperName (oper), left.GetSignatureForError (), right.GetSignatureForError ());

                                        best_operator = po;
                                        break;
                                }
                        }

                        if (best_operator == null)
                                return null;

                        Expression expr = best_operator.ConvertResult (ec, this);
                        if (enum_type == null)
                                return expr;

                        //
                        // HACK: required by enum_conversion
                        //
                        expr.Type = enum_type;
                        return EmptyCast.Create (expr, enum_type);
                }

                //
                // Performs user-operator overloading
                //
                protected virtual Expression ResolveUserOperator (EmitContext ec, Type l, Type r)
                {
                        Operator user_oper;
                        if (oper == Operator.LogicalAnd)
                                user_oper = Operator.BitwiseAnd;
                        else if (oper == Operator.LogicalOr)
                                user_oper = Operator.BitwiseOr;
                        else
                                user_oper = oper;

                        string op = GetOperatorMetadataName (user_oper);

                        MethodGroupExpr left_operators = MemberLookup (ec.ContainerType, l, op, MemberTypes.Method, AllBindingFlags, loc) as MethodGroupExpr;
                        MethodGroupExpr right_operators = null;

                        if (!TypeManager.IsEqual (r, l)) {
                                right_operators = MemberLookup (ec.ContainerType, r, op, MemberTypes.Method, AllBindingFlags, loc) as MethodGroupExpr;
                                if (right_operators == null && left_operators == null)
                                        return null;
                        } else if (left_operators == null) {
                                return null;
                        }

                        ArrayList args = new ArrayList (2);
                        Argument larg = new Argument (left);
                        args.Add (larg);
                        Argument rarg = new Argument (right);
                        args.Add (rarg);

                        MethodGroupExpr union;

                        //
                        // User-defined operator implementations always take precedence
                        // over predefined operator implementations
                        //
                        if (left_operators != null && right_operators != null) {
                                if (IsPredefinedUserOperator (l, user_oper)) {
                                        union = right_operators.OverloadResolve (ec, ref args, true, loc);
                                        if (union == null)
                                                union = left_operators;
                                } else if (IsPredefinedUserOperator (r, user_oper)) {
                                        union = left_operators.OverloadResolve (ec, ref args, true, loc);
                                        if (union == null)
                                                union = right_operators;
                                } else {
                                        union = MethodGroupExpr.MakeUnionSet (left_operators, right_operators, loc);
                                }
                        } else if (left_operators != null) {
                                union = left_operators;
                        } else {
                                union = right_operators;
                        }

                        union = union.OverloadResolve (ec, ref args, true, loc);
                        if (union == null)
                                return null;

                        Expression oper_expr;

                        // TODO: CreateExpressionTree is allocated every time
                        if (user_oper != oper) {
                                oper_expr = new ConditionalLogicalOperator (union, args, CreateExpressionTree,
                                        oper == Operator.LogicalAnd, loc).Resolve (ec);
                        } else {
                                oper_expr = new UserOperatorCall (union, args, CreateExpressionTree, loc);

                                //
                                // This is used to check if a test 'x == null' can be optimized to a reference equals,
                                // and not invoke user operator
                                //
                                if ((oper & Operator.EqualityMask) != 0) {
                                        if ((left is NullLiteral && IsBuildInEqualityOperator (r)) ||
                                                (right is NullLiteral && IsBuildInEqualityOperator (l))) {
                                                type = TypeManager.bool_type;
                                                if (left is NullLiteral || right is NullLiteral)
                                                        oper_expr = ReducedExpression.Create (this, oper_expr).Resolve (ec);
                                        } else if (l != r) {
                                                MethodInfo mi = (MethodInfo) union;
                                                
                                                //
                                                // Two System.Delegate(s) are never equal
                                                //
                                                if (mi.DeclaringType == TypeManager.multicast_delegate_type)
                                                        return null;
                                        }
                                }
                        }

                        left = larg.Expr;
                        right = rarg.Expr;
                        return oper_expr;
                }

                public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
                {
                        return null;
                }

                private void CheckUselessComparison (Constant c, Type type)
                {
                        if (c == null || !IsTypeIntegral (type)
                                || c is StringConstant
                                || c is BoolConstant
                                || c is FloatConstant
                                || c is DoubleConstant
                                || c is DecimalConstant
                                )
                                return;

                        long value = 0;

                        if (c is ULongConstant) {
                                ulong uvalue = ((ULongConstant) c).Value;
                                if (uvalue > long.MaxValue) {
                                        if (type == TypeManager.byte_type ||
                                            type == TypeManager.sbyte_type ||
                                            type == TypeManager.short_type ||
                                            type == TypeManager.ushort_type ||
                                            type == TypeManager.int32_type ||
                                            type == TypeManager.uint32_type ||
                                            type == TypeManager.int64_type ||
                                                type == TypeManager.char_type)
                                                WarnUselessComparison (type);
                                        return;
                                }
                                value = (long) uvalue;
                        }
                        else if (c is ByteConstant)
                                value = ((ByteConstant) c).Value;
                        else if (c is SByteConstant)
                                value = ((SByteConstant) c).Value;
                        else if (c is ShortConstant)
                                value = ((ShortConstant) c).Value;
                        else if (c is UShortConstant)
                                value = ((UShortConstant) c).Value;
                        else if (c is IntConstant)
                                value = ((IntConstant) c).Value;
                        else if (c is UIntConstant)
                                value = ((UIntConstant) c).Value;
                        else if (c is LongConstant)
                                value = ((LongConstant) c).Value;
                        else if (c is CharConstant)
                                value = ((CharConstant)c).Value;

                        if (value == 0)
                                return;

                        if (IsValueOutOfRange (value, type))
                                WarnUselessComparison (type);
                }

                static bool IsValueOutOfRange (long value, Type type)
                {
                        if (IsTypeUnsigned (type) && value < 0)
                                return true;
                        return type == TypeManager.sbyte_type && (value >= 0x80 || value < -0x80) ||
                                type == TypeManager.byte_type && value >= 0x100 ||
                                type == TypeManager.short_type && (value >= 0x8000 || value < -0x8000) ||
                                type == TypeManager.ushort_type && value >= 0x10000 ||
                                type == TypeManager.int32_type && (value >= 0x80000000 || value < -0x80000000) ||
                                type == TypeManager.uint32_type && value >= 0x100000000;
                }

                static bool IsBuildInEqualityOperator (Type t)
                {
                        return t == TypeManager.object_type || t == TypeManager.string_type ||
                                t == TypeManager.delegate_type || TypeManager.IsDelegateType (t);
                }

                static bool IsPredefinedUserOperator (Type t, Operator op)
                {
                        //
                        // Some predefined types have user operators
                        //
                        return (op & Operator.EqualityMask) != 0 && (t == TypeManager.string_type || t == TypeManager.decimal_type);
                }

                private static bool IsTypeIntegral (Type type)
                {
                        return type == TypeManager.uint64_type ||
                                type == TypeManager.int64_type ||
                                type == TypeManager.uint32_type ||
                                type == TypeManager.int32_type ||
                                type == TypeManager.ushort_type ||
                                type == TypeManager.short_type ||
                                type == TypeManager.sbyte_type ||
                                type == TypeManager.byte_type ||
                                type == TypeManager.char_type;
                }

                private static bool IsTypeUnsigned (Type type)
                {
                        return type == TypeManager.uint64_type ||
                                type == TypeManager.uint32_type ||
                                type == TypeManager.ushort_type ||
                                type == TypeManager.byte_type ||
                                type == TypeManager.char_type;
                }

                private void WarnUselessComparison (Type type)
                {
                        Report.Warning (652, 2, loc, "A comparison between a constant and a variable is useless. The constant is out of the range of the variable type `{0}'",
                                TypeManager.CSharpName (type));
                }

                /// <remarks>
                ///   EmitBranchable is called from Statement.EmitBoolExpression in the
                ///   context of a conditional bool expression.  This function will return
                ///   false if it is was possible to use EmitBranchable, or true if it was.
                ///
                ///   The expression's code is generated, and we will generate a branch to `target'
                ///   if the resulting expression value is equal to isTrue
                /// </remarks>
                public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
                {
                        ILGenerator ig = ec.ig;

                        //
                        // This is more complicated than it looks, but its just to avoid
                        // duplicated tests: basically, we allow ==, !=, >, <, >= and <=
                        // but on top of that we want for == and != to use a special path
                        // if we are comparing against null
                        //
                        if ((oper == Operator.Equality || oper == Operator.Inequality) && (left is Constant || right is Constant)) {
                                bool my_on_true = oper == Operator.Inequality ? on_true : !on_true;
                                
                                //
                                // put the constant on the rhs, for simplicity
                                //
                                if (left is Constant) {
                                        Expression swap = right;
                                        right = left;
                                        left = swap;
                                }
                                
                                if (((Constant) right).IsZeroInteger) {
                                        left.EmitBranchable (ec, target, my_on_true);
                                        return;
                                }
                                if (right.Type == TypeManager.bool_type) {
                                        // right is a boolean, and it's not 'false' => it is 'true'
                                        left.EmitBranchable (ec, target, !my_on_true);
                                        return;
                                }

                        } else if (oper == Operator.LogicalAnd) {

                                if (on_true) {
                                        Label tests_end = ig.DefineLabel ();
                                        
                                        left.EmitBranchable (ec, tests_end, false);
                                        right.EmitBranchable (ec, target, true);
                                        ig.MarkLabel (tests_end);                                       
                                } else {
                                        //
                                        // This optimizes code like this 
                                        // if (true && i > 4)
                                        //
                                        if (!(left is Constant))
                                                left.EmitBranchable (ec, target, false);

                                        if (!(right is Constant)) 
                                                right.EmitBranchable (ec, target, false);
                                }
                                
                                return;
                                
                        } else if (oper == Operator.LogicalOr){
                                if (on_true) {
                                        left.EmitBranchable (ec, target, true);
                                        right.EmitBranchable (ec, target, true);
                                        
                                } else {
                                        Label tests_end = ig.DefineLabel ();
                                        left.EmitBranchable (ec, tests_end, true);
                                        right.EmitBranchable (ec, target, false);
                                        ig.MarkLabel (tests_end);
                                }
                                
                                return;
                                
                        } else if (!(oper == Operator.LessThan        || oper == Operator.GreaterThan ||
                                     oper == Operator.LessThanOrEqual || oper == Operator.GreaterThanOrEqual ||
                                     oper == Operator.Equality        || oper == Operator.Inequality)) {
                                base.EmitBranchable (ec, target, on_true);
                                return;
                        }
                        
                        left.Emit (ec);
                        right.Emit (ec);

                        Type t = left.Type;
                        bool is_float = IsFloat (t);
                        bool is_unsigned = is_float || IsUnsigned (t);
                        
                        switch (oper){
                        case Operator.Equality:
                                if (on_true)
                                        ig.Emit (OpCodes.Beq, target);
                                else
                                        ig.Emit (OpCodes.Bne_Un, target);
                                break;

                        case Operator.Inequality:
                                if (on_true)
                                        ig.Emit (OpCodes.Bne_Un, target);
                                else
                                        ig.Emit (OpCodes.Beq, target);
                                break;

                        case Operator.LessThan:
                                if (on_true)
                                        if (is_unsigned && !is_float)
                                                ig.Emit (OpCodes.Blt_Un, target);
                                        else
                                                ig.Emit (OpCodes.Blt, target);
                                else
                                        if (is_unsigned)
                                                ig.Emit (OpCodes.Bge_Un, target);
                                        else
                                                ig.Emit (OpCodes.Bge, target);
                                break;

                        case Operator.GreaterThan:
                                if (on_true)
                                        if (is_unsigned && !is_float)
                                                ig.Emit (OpCodes.Bgt_Un, target);
                                        else
                                                ig.Emit (OpCodes.Bgt, target);
                                else
                                        if (is_unsigned)
                                                ig.Emit (OpCodes.Ble_Un, target);
                                        else
                                                ig.Emit (OpCodes.Ble, target);
                                break;

                        case Operator.LessThanOrEqual:
                                if (on_true)
                                        if (is_unsigned && !is_float)
                                                ig.Emit (OpCodes.Ble_Un, target);
                                        else
                                                ig.Emit (OpCodes.Ble, target);
                                else
                                        if (is_unsigned)
                                                ig.Emit (OpCodes.Bgt_Un, target);
                                        else
                                                ig.Emit (OpCodes.Bgt, target);
                                break;


                        case Operator.GreaterThanOrEqual:
                                if (on_true)
                                        if (is_unsigned && !is_float)
                                                ig.Emit (OpCodes.Bge_Un, target);
                                        else
                                                ig.Emit (OpCodes.Bge, target);
                                else
                                        if (is_unsigned)
                                                ig.Emit (OpCodes.Blt_Un, target);
                                        else
                                                ig.Emit (OpCodes.Blt, target);
                                break;
                        default:
                                throw new InternalErrorException (oper.ToString ());
                        }
                }
                
                public override void Emit (EmitContext ec)
                {
                        EmitOperator (ec, left.Type);
                }

                protected virtual void EmitOperator (EmitContext ec, Type l)
                {
                        ILGenerator ig = ec.ig;

                        //
                        // Handle short-circuit operators differently
                        // than the rest
                        //
                        if ((oper & Operator.LogicalMask) != 0) {
                                Label load_result = ig.DefineLabel ();
                                Label end = ig.DefineLabel ();

                                bool is_or = oper == Operator.LogicalOr;
                                left.EmitBranchable (ec, load_result, is_or);
                                right.Emit (ec);
                                ig.Emit (OpCodes.Br_S, end);
                                
                                ig.MarkLabel (load_result);
                                ig.Emit (is_or ? OpCodes.Ldc_I4_1 : OpCodes.Ldc_I4_0);
                                ig.MarkLabel (end);
                                return;
                        }

                        left.Emit (ec);

                        //
                        // Optimize zero-based operations
                        //
                        // TODO: Implement more optimizations, but it should probably go to PredefinedOperators
                        //
                        if ((oper & Operator.ShiftMask) != 0 || oper == Operator.Addition || oper == Operator.Subtraction) {
                                Constant rc = right as Constant;
                                if (rc != null && rc.IsDefaultValue) {
                                        return;
                                }
                        }

                        right.Emit (ec);
                        EmitOperatorOpcode (ec, oper, l);

                        //
                        // Nullable enum could require underlying type cast and we cannot simply wrap binary
                        // expression because that would wrap lifted binary operation
                        //
                        if (enum_conversion != null)
                                enum_conversion.Emit (ec);
                }

                public override void EmitSideEffect (EmitContext ec)
                {
                        if ((oper & Operator.LogicalMask) != 0 ||
                            (ec.CheckState && (oper == Operator.Multiply || oper == Operator.Addition || oper == Operator.Subtraction))) {
                                base.EmitSideEffect (ec);
                        } else {
                                left.EmitSideEffect (ec);
                                right.EmitSideEffect (ec);
                        }
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Binary target = (Binary) t;

                        target.left = left.Clone (clonectx);
                        target.right = right.Clone (clonectx);
                }
                
                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        return CreateExpressionTree (ec, null);
                }

                Expression CreateExpressionTree (EmitContext ec, MethodGroupExpr method)                
                {
                        string method_name;
                        bool lift_arg = false;
                        
                        switch (oper) {
                        case Operator.Addition:
                                if (method == null && ec.CheckState && !IsFloat (type))
                                        method_name = "AddChecked";
                                else
                                        method_name = "Add";
                                break;
                        case Operator.BitwiseAnd:
                                method_name = "And";
                                break;
                        case Operator.BitwiseOr:
                                method_name = "Or";
                                break;
                        case Operator.Division:
                                method_name = "Divide";
                                break;
                        case Operator.Equality:
                                method_name = "Equal";
                                lift_arg = true;
                                break;
                        case Operator.ExclusiveOr:
                                method_name = "ExclusiveOr";
                                break;                          
                        case Operator.GreaterThan:
                                method_name = "GreaterThan";
                                lift_arg = true;
                                break;
                        case Operator.GreaterThanOrEqual:
                                method_name = "GreaterThanOrEqual";
                                lift_arg = true;
                                break;
                        case Operator.Inequality:
                                method_name = "NotEqual";
                                lift_arg = true;
                                break;
                        case Operator.LeftShift:
                                method_name = "LeftShift";
                                break;
                        case Operator.LessThan:
                                method_name = "LessThan";
                                lift_arg = true;
                                break;
                        case Operator.LessThanOrEqual:
                                method_name = "LessThanOrEqual";
                                lift_arg = true;
                                break;
                        case Operator.LogicalAnd:
                                method_name = "AndAlso";
                                break;
                        case Operator.LogicalOr:
                                method_name = "OrElse";
                                break;
                        case Operator.Modulus:
                                method_name = "Modulo";
                                break;
                        case Operator.Multiply:
                                if (method == null && ec.CheckState && !IsFloat (type))
                                        method_name = "MultiplyChecked";
                                else
                                        method_name = "Multiply";
                                break;
                        case Operator.RightShift:
                                method_name = "RightShift";
                                break;
                        case Operator.Subtraction:
                                if (method == null && ec.CheckState && !IsFloat (type))
                                        method_name = "SubtractChecked";
                                else
                                        method_name = "Subtract";
                                break;

                        default:
                                throw new InternalErrorException ("Unknown expression tree binary operator " + oper);
                        }

                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (left.CreateExpressionTree (ec)));
                        args.Add (new Argument (right.CreateExpressionTree (ec)));
                        if (method != null) {
                                if (lift_arg)
                                        args.Add (new Argument (new BoolConstant (false, loc)));
                                
                                args.Add (new Argument (method.CreateExpressionTree (ec)));
                        }
                        
                        return CreateExpressionFactoryCall (method_name, args);
                }
        }
        
        //
        // Represents the operation a + b [+ c [+ d [+ ...]]], where a is a string
        // b, c, d... may be strings or objects.
        //
        public class StringConcat : Expression {
                ArrayList arguments;
                
                public StringConcat (EmitContext ec, Location loc, Expression left, Expression right)
                {
                        this.loc = loc;
                        type = TypeManager.string_type;
                        eclass = ExprClass.Value;

                        arguments = new ArrayList (2);
                        Append (ec, left);
                        Append (ec, right);
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        Argument arg = (Argument) arguments [0];
                        return CreateExpressionAddCall (ec, arg, arg.Expr.CreateExpressionTree (ec), 1);
                }

                //
                // Creates nested calls tree from an array of arguments used for IL emit
                //
                Expression CreateExpressionAddCall (EmitContext ec, Argument left, Expression left_etree, int pos)
                {
                        ArrayList concat_args = new ArrayList (2);
                        ArrayList add_args = new ArrayList (3);

                        concat_args.Add (left);
                        add_args.Add (new Argument (left_etree));

                        concat_args.Add (arguments [pos]);
                        add_args.Add (new Argument (((Argument) arguments [pos]).Expr.CreateExpressionTree (ec)));

                        MethodGroupExpr method = CreateConcatMemberExpression ().Resolve (ec) as MethodGroupExpr;
                        if (method == null)
                                return null;

                        method = method.OverloadResolve (ec, ref concat_args, false, loc);
                        if (method == null)
                                return null;

                        add_args.Add (new Argument (method.CreateExpressionTree (ec)));

                        Expression expr = CreateExpressionFactoryCall ("Add", add_args);
                        if (++pos == arguments.Count)
                                return expr;

                        left = new Argument (new EmptyExpression (((MethodInfo)method).ReturnType));
                        return CreateExpressionAddCall (ec, left, expr, pos);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        return this;
                }
                
                public void Append (EmitContext ec, Expression operand)
                {
                        //
                        // Constant folding
                        //
                        StringConstant sc = operand as StringConstant;
                        if (sc != null) {
                                if (arguments.Count != 0) {
                                        Argument last_argument = (Argument) arguments [arguments.Count - 1];
                                        StringConstant last_expr_constant = last_argument.Expr as StringConstant;
                                        if (last_expr_constant != null) {
                                                last_argument.Expr = new StringConstant (
                                                        last_expr_constant.Value + sc.Value, sc.Location);
                                                return;
                                        }
                                }
                        } else {
                                //
                                // Multiple (3+) concatenation are resolved as multiple StringConcat instances
                                //
                                StringConcat concat_oper = operand as StringConcat;
                                if (concat_oper != null) {
                                        arguments.AddRange (concat_oper.arguments);
                                        return;
                                }
                        }

                        arguments.Add (new Argument (operand));
                }

                Expression CreateConcatMemberExpression ()
                {
                        return new MemberAccess (new MemberAccess (new QualifiedAliasMember ("global", "System", loc), "String", loc), "Concat", loc);
                }

                public override void Emit (EmitContext ec)
                {
                        Expression concat = new Invocation (CreateConcatMemberExpression (), arguments, true);
                        concat = concat.Resolve (ec);
                        if (concat != null)
                                concat.Emit (ec);
                }
                
                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        foreach (Argument a in arguments)
                                a.Expr.MutateHoistedGenericType (storey);
                }               
        }

        //
        // User-defined conditional logical operator
        //
        public class ConditionalLogicalOperator : UserOperatorCall {
                readonly bool is_and;
                Expression oper;

                public ConditionalLogicalOperator (MethodGroupExpr oper_method, ArrayList arguments,
                        ExpressionTreeExpression expr_tree, bool is_and, Location loc)
                        : base (oper_method, arguments, expr_tree, loc)
                {
                        this.is_and = is_and;
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        MethodInfo method = (MethodInfo)mg;
                        type = TypeManager.TypeToCoreType (method.ReturnType);
                        AParametersCollection pd = TypeManager.GetParameterData (method);
                        if (!TypeManager.IsEqual (type, type) || !TypeManager.IsEqual (type, pd.Types [0]) || !TypeManager.IsEqual (type, pd.Types [1])) {
                                Report.Error (217, loc,
                                        "A user-defined operator `{0}' must have parameters and return values of the same type in order to be applicable as a short circuit operator",
                                        TypeManager.CSharpSignature (method));
                                return null;
                        }

                        Expression left_dup = new EmptyExpression (type);
                        Expression op_true = GetOperatorTrue (ec, left_dup, loc);
                        Expression op_false = GetOperatorFalse (ec, left_dup, loc);
                        if (op_true == null || op_false == null) {
                                Report.Error (218, loc,
                                        "The type `{0}' must have operator `true' and operator `false' defined when `{1}' is used as a short circuit operator",
                                        TypeManager.CSharpName (type), TypeManager.CSharpSignature (method));
                                return null;
                        }

                        oper = is_and ? op_false : op_true;
                        eclass = ExprClass.Value;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        ILGenerator ig = ec.ig;
                        Label end_target = ig.DefineLabel ();

                        //
                        // Emit and duplicate left argument
                        //
                        ((Argument)arguments [0]).Expr.Emit (ec);
                        ig.Emit (OpCodes.Dup);
                        arguments.RemoveAt (0);

                        oper.EmitBranchable (ec, end_target, true);
                        base.Emit (ec);
                        ig.MarkLabel (end_target);
                }
        }

        public class PointerArithmetic : Expression {
                Expression left, right;
                Binary.Operator op;

                //
                // We assume that `l' is always a pointer
                //
                public PointerArithmetic (Binary.Operator op, Expression l, Expression r, Type t, Location loc)
                {
                        type = t;
                        this.loc = loc;
                        left = l;
                        right = r;
                        this.op = op;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        Error_PointerInsideExpressionTree ();
                        return null;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        eclass = ExprClass.Variable;
                        
                        if (left.Type == TypeManager.void_ptr_type) {
                                Error (242, "The operation in question is undefined on void pointers");
                                return null;
                        }
                        
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        Type op_type = left.Type;
                        ILGenerator ig = ec.ig;
                        
                        // It must be either array or fixed buffer
                        Type element;
                        if (TypeManager.HasElementType (op_type)) {
                                element = TypeManager.GetElementType (op_type);
                        } else {
                                FieldExpr fe = left as FieldExpr;
                                if (fe != null)
                                        element = AttributeTester.GetFixedBuffer (fe.FieldInfo).ElementType;
                                else
                                        element = op_type;
                        }

                        int size = GetTypeSize (element);
                        Type rtype = right.Type;
                        
                        if ((op & Binary.Operator.SubtractionMask) != 0 && rtype.IsPointer){
                                //
                                // handle (pointer - pointer)
                                //
                                left.Emit (ec);
                                right.Emit (ec);
                                ig.Emit (OpCodes.Sub);

                                if (size != 1){
                                        if (size == 0)
                                                ig.Emit (OpCodes.Sizeof, element);
                                        else 
                                                IntLiteral.EmitInt (ig, size);
                                        ig.Emit (OpCodes.Div);
                                }
                                ig.Emit (OpCodes.Conv_I8);
                        } else {
                                //
                                // handle + and - on (pointer op int)
                                //
                                Constant left_const = left as Constant;
                                if (left_const != null) {
                                        //
                                        // Optimize ((T*)null) pointer operations
                                        //
                                        if (left_const.IsDefaultValue) {
                                                left = EmptyExpression.Null;
                                        } else {
                                                left_const = null;
                                        }
                                }

                                left.Emit (ec);

                                Constant right_const = right as Constant;
                                if (right_const != null) {
                                        //
                                        // Optimize 0-based arithmetic
                                        //
                                        if (right_const.IsDefaultValue)
                                                return;

                                        if (size != 0) {
                                                right = ConstantFold.BinaryFold (ec, Binary.Operator.Multiply, new IntConstant (size, right.Location), right_const, loc);
                                                if (right == null)
                                                        return;
                                        } else {
                                                ig.Emit (OpCodes.Sizeof, element);
                                                right = EmptyExpression.Null;
                                        }
                                }

                                right.Emit (ec);
                                if (rtype == TypeManager.sbyte_type || rtype == TypeManager.byte_type ||
                                        rtype == TypeManager.short_type || rtype == TypeManager.ushort_type) {
                                        ig.Emit (OpCodes.Conv_I);
                                } else if (rtype == TypeManager.uint32_type) {
                                        ig.Emit (OpCodes.Conv_U);
                                }

                                if (right_const == null && size != 1){
                                        if (size == 0)
                                                ig.Emit (OpCodes.Sizeof, element);
                                        else 
                                                IntLiteral.EmitInt (ig, size);
                                        if (rtype == TypeManager.int64_type || rtype == TypeManager.uint64_type)
                                                ig.Emit (OpCodes.Conv_I8);

                                        Binary.EmitOperatorOpcode (ec, Binary.Operator.Multiply, rtype);
                                }

                                if (left_const == null) {
                                        if (rtype == TypeManager.int64_type)
                                                ig.Emit (OpCodes.Conv_I);
                                        else if (rtype == TypeManager.uint64_type)
                                                ig.Emit (OpCodes.Conv_U);

                                        Binary.EmitOperatorOpcode (ec, op, op_type);
                                }
                        }
                }
        }
        
        /// <summary>
        ///   Implements the ternary conditional operator (?:)
        /// </summary>
        public class Conditional : Expression {
                Expression expr, true_expr, false_expr;
                
                public Conditional (Expression expr, Expression true_expr, Expression false_expr)
                {
                        this.expr = expr;
                        this.true_expr = true_expr;
                        this.false_expr = false_expr;
                        this.loc = expr.Location;
                }

                public Expression Expr {
                        get {
                                return expr;
                        }
                }

                public Expression TrueExpr {
                        get {
                                return true_expr;
                        }
                }

                public Expression FalseExpr {
                        get {
                                return false_expr;
                        }
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (3);
                        args.Add (new Argument (expr.CreateExpressionTree (ec)));
                        args.Add (new Argument (true_expr.CreateExpressionTree (ec)));
                        args.Add (new Argument (false_expr.CreateExpressionTree (ec)));
                        return CreateExpressionFactoryCall ("Condition", args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        expr = expr.Resolve (ec);

                        if (expr == null)
                                return null;

                        if (expr.Type != TypeManager.bool_type){
                                expr = Expression.ResolveBoolean (
                                        ec, expr, loc);
                                
                                if (expr == null)
                                        return null;
                        }
                        
                        Assign ass = expr as Assign;
                        if (ass != null && ass.Source is Constant) {
                                Report.Warning (665, 3, loc, "Assignment in conditional expression is always constant; did you mean to use == instead of = ?");
                        }

                        true_expr = true_expr.Resolve (ec);
                        false_expr = false_expr.Resolve (ec);

                        if (true_expr == null || false_expr == null)
                                return null;

                        eclass = ExprClass.Value;
                        Type true_type = true_expr.Type;
                        Type false_type = false_expr.Type;
                        type = true_type;

                        //
                        // First, if an implicit conversion exists from true_expr
                        // to false_expr, then the result type is of type false_expr.Type
                        //
                        if (!TypeManager.IsEqual (true_type, false_type)) {
                                Expression conv = Convert.ImplicitConversion (ec, true_expr, false_type, loc);
                                if (conv != null) {
                                        //
                                        // Check if both can convert implicitl to each other's type
                                        //
                                        if (Convert.ImplicitConversion (ec, false_expr, true_type, loc) != null) {
                                                Error (172,
                                                           "Can not compute type of conditional expression " +
                                                           "as `" + TypeManager.CSharpName (true_expr.Type) +
                                                           "' and `" + TypeManager.CSharpName (false_expr.Type) +
                                                           "' convert implicitly to each other");
                                                return null;
                                        }
                                        type = false_type;
                                        true_expr = conv;
                                } else if ((conv = Convert.ImplicitConversion (ec, false_expr, true_type, loc)) != null) {
                                        false_expr = conv;
                                } else {
                                        Report.Error (173, loc,
                                                "Type of conditional expression cannot be determined because there is no implicit conversion between `{0}' and `{1}'",
                                                true_expr.GetSignatureForError (), false_expr.GetSignatureForError ());
                                        return null;
                                }
                        }                       

                        // Dead code optimalization
                        Constant c = expr as Constant;
                        if (c != null){
                                bool is_false = c.IsDefaultValue;
                                Report.Warning (429, 4, is_false ? true_expr.Location : false_expr.Location, "Unreachable expression code detected");
                                return ReducedExpression.Create (is_false ? false_expr : true_expr, this).Resolve (ec);
                        }

                        return this;
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        expr.MutateHoistedGenericType (storey);
                        true_expr.MutateHoistedGenericType (storey);
                        false_expr.MutateHoistedGenericType (storey);
                        type = storey.MutateType (type);
                }

                public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
                {
                        return null;
                }

                public override void Emit (EmitContext ec)
                {
                        ILGenerator ig = ec.ig;
                        Label false_target = ig.DefineLabel ();
                        Label end_target = ig.DefineLabel ();

                        expr.EmitBranchable (ec, false_target, false);
                        true_expr.Emit (ec);

                        if (type.IsInterface) {
                                LocalBuilder temp = ec.GetTemporaryLocal (type);
                                ig.Emit (OpCodes.Stloc, temp);
                                ig.Emit (OpCodes.Ldloc, temp);
                                ec.FreeTemporaryLocal (temp, type);
                        }

                        ig.Emit (OpCodes.Br, end_target);
                        ig.MarkLabel (false_target);
                        false_expr.Emit (ec);
                        ig.MarkLabel (end_target);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Conditional target = (Conditional) t;

                        target.expr = expr.Clone (clonectx);
                        target.true_expr = true_expr.Clone (clonectx);
                        target.false_expr = false_expr.Clone (clonectx);
                }
        }

        public abstract class VariableReference : Expression, IAssignMethod, IMemoryLocation, IVariableReference {
                LocalTemporary temp;

                #region Abstract
                public abstract HoistedVariable GetHoistedVariable (EmitContext ec);
                public abstract bool IsFixed { get; }
                public abstract bool IsRef { get; }
                public abstract string Name { get; }
                public abstract void SetHasAddressTaken ();

                //
                // Variable IL data, it has to be protected to encapsulate hoisted variables
                //
                protected abstract ILocalVariable Variable { get; }
                
                //
                // Variable flow-analysis data
                //
                public abstract VariableInfo VariableInfo { get; }
                #endregion

                public void AddressOf (EmitContext ec, AddressOp mode)
                {
                        HoistedVariable hv = GetHoistedVariable (ec);
                        if (hv != null) {
                                hv.AddressOf (ec, mode);
                                return;
                        }

                        Variable.EmitAddressOf (ec);
                }

                public override void Emit (EmitContext ec)
                {
                        Emit (ec, false);
                }

                public override void EmitSideEffect (EmitContext ec)
                {
                        // do nothing
                }

                //
                // This method is used by parameters that are references, that are
                // being passed as references:  we only want to pass the pointer (that
                // is already stored in the parameter, not the address of the pointer,
                // and not the value of the variable).
                //
                public void EmitLoad (EmitContext ec)
                {
                        Variable.Emit (ec);
                }

                public void Emit (EmitContext ec, bool leave_copy)
                {
                        Report.Debug (64, "VARIABLE EMIT", this, Variable, type, IsRef, loc);

                        HoistedVariable hv = GetHoistedVariable (ec);
                        if (hv != null) {
                                hv.Emit (ec, leave_copy);
                                return;
                        }

                        EmitLoad (ec);

                        if (IsRef) {
                                //
                                // If we are a reference, we loaded on the stack a pointer
                                // Now lets load the real value
                                //
                                LoadFromPtr (ec.ig, type);
                        }

                        if (leave_copy) {
                                ec.ig.Emit (OpCodes.Dup);

                                if (IsRef) {
                                        temp = new LocalTemporary (Type);
                                        temp.Store (ec);
                                }
                        }
                }

                public void EmitAssign (EmitContext ec, Expression source, bool leave_copy,
                                        bool prepare_for_load)
                {
                        HoistedVariable hv = GetHoistedVariable (ec);
                        if (hv != null) {
                                hv.EmitAssign (ec, source, leave_copy, prepare_for_load);
                                return;
                        }

                        New n_source = source as New;
                        if (n_source != null) {
                                if (!n_source.Emit (ec, this)) {
                                        if (leave_copy)
                                                EmitLoad (ec);
                                        return;
                                }
                        } else {
                                if (IsRef)
                                        EmitLoad (ec);

                                source.Emit (ec);
                        }

                        if (leave_copy) {
                                ec.ig.Emit (OpCodes.Dup);
                                if (IsRef) {
                                        temp = new LocalTemporary (Type);
                                        temp.Store (ec);
                                }
                        }

                        if (IsRef)
                                StoreFromPtr (ec.ig, type);
                        else
                                Variable.EmitAssign (ec);

                        if (temp != null) {
                                temp.Emit (ec);
                                temp.Release (ec);
                        }
                }

                public bool IsHoisted {
                        get { return GetHoistedVariable (null) != null; }
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        type = storey.MutateType (type);
                }
        }

        /// <summary>
        ///   Local variables
        /// </summary>
        public class LocalVariableReference : VariableReference {
                readonly string name;
                public Block Block;
                public LocalInfo local_info;
                bool is_readonly;

                public LocalVariableReference (Block block, string name, Location l)
                {
                        Block = block;
                        this.name = name;
                        loc = l;
                        eclass = ExprClass.Variable;
                }

                //
                // Setting `is_readonly' to false will allow you to create a writable
                // reference to a read-only variable.  This is used by foreach and using.
                //
                public LocalVariableReference (Block block, string name, Location l,
                                               LocalInfo local_info, bool is_readonly)
                        : this (block, name, l)
                {
                        this.local_info = local_info;
                        this.is_readonly = is_readonly;
                }

                public override VariableInfo VariableInfo {
                        get { return local_info.VariableInfo; }
                }

                public override HoistedVariable GetHoistedVariable (EmitContext ec)
                {
                        return local_info.HoistedVariableReference;
                }

                //              
                // A local variable is always fixed
                //
                public override bool IsFixed {
                        get { return true; }
                }

                public override bool IsRef {
                        get { return false; }
                }

                public bool IsReadOnly {
                        get { return is_readonly; }
                }

                public override string Name {
                        get { return name; }
                }

                public bool VerifyAssigned (EmitContext ec)
                {
                        VariableInfo variable_info = local_info.VariableInfo;
                        return variable_info == null || variable_info.IsAssigned (ec, loc);
                }

                void ResolveLocalInfo ()
                {
                        if (local_info == null) {
                                local_info = Block.GetLocalInfo (Name);
                                type = local_info.VariableType;
                                is_readonly = local_info.ReadOnly;
                        }
                }

                public override void SetHasAddressTaken ()
                {
                        local_info.AddressTaken = true;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        HoistedVariable hv = GetHoistedVariable (ec);
                        if (hv != null)
                                return hv.CreateExpressionTree (ec);
                                
                        ArrayList arg = new ArrayList (1);
                        arg.Add (new Argument (this));
                        return CreateExpressionFactoryCall ("Constant", arg);
                }

                Expression DoResolveBase (EmitContext ec)
                {
                        type = local_info.VariableType;

                        Expression e = Block.GetConstantExpression (Name);
                        if (e != null)
                                return e.Resolve (ec);

                        VerifyAssigned (ec);

                        //
                        // If we are referencing a variable from the external block
                        // flag it for capturing
                        //
                        if (ec.MustCaptureVariable (local_info)) {
                                if (local_info.AddressTaken)
                                        AnonymousMethodExpression.Error_AddressOfCapturedVar (this, loc);

                                if (ec.IsVariableCapturingRequired) {
                                        AnonymousMethodStorey storey = local_info.Block.Explicit.CreateAnonymousMethodStorey (ec);
                                        storey.CaptureLocalVariable (ec, local_info);
                                }
                        }

                        return this;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        ResolveLocalInfo ();
                        local_info.Used = true;

                        if (type == null && local_info.Type is VarExpr) {
                            local_info.VariableType = TypeManager.object_type;
                                Error_VariableIsUsedBeforeItIsDeclared (Name);
                            return null;
                        }
                        
                        return DoResolveBase (ec);
                }

                override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        ResolveLocalInfo ();

                        // is out param
                        if (right_side == EmptyExpression.OutAccess)
                                local_info.Used = true;

                        // Infer implicitly typed local variable
                        if (type == null) {
                                VarExpr ve = local_info.Type as VarExpr;
                                if (ve != null) {
                                        if (!ve.InferType (ec, right_side))
                                                return null;
                                        type = local_info.VariableType = ve.Type;
                                }
                        }
                                                
                        if (is_readonly) {
                                int code;
                                string msg;
                                if (right_side == EmptyExpression.OutAccess) {
                                        code = 1657; msg = "Cannot pass `{0}' as a ref or out argument because it is a `{1}'";
                                } else if (right_side == EmptyExpression.LValueMemberAccess) {
                                        code = 1654; msg = "Cannot assign to members of `{0}' because it is a `{1}'";
                                } else if (right_side == EmptyExpression.LValueMemberOutAccess) {
                                        code = 1655; msg = "Cannot pass members of `{0}' as ref or out arguments because it is a `{1}'";
                                } else if (right_side == EmptyExpression.UnaryAddress) {
                                        code = 459; msg = "Cannot take the address of {1} `{0}'";
                                } else {
                                        code = 1656; msg = "Cannot assign to `{0}' because it is a `{1}'";
                                }
                                Report.Error (code, loc, msg, Name, local_info.GetReadOnlyContext ());
                        } else if (VariableInfo != null) {
                                VariableInfo.SetAssigned (ec);
                        }

                        return DoResolveBase (ec);
                }

                public override int GetHashCode ()
                {
                        return Name.GetHashCode ();
                }

                public override bool Equals (object obj)
                {
                        LocalVariableReference lvr = obj as LocalVariableReference;
                        if (lvr == null)
                                return false;

                        return Name == lvr.Name && Block == lvr.Block;
                }

                protected override ILocalVariable Variable {
                        get { return local_info; }
                }

                public override string ToString ()
                {
                        return String.Format ("{0} ({1}:{2})", GetType (), Name, loc);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        LocalVariableReference target = (LocalVariableReference) t;
                        
                        target.Block = clonectx.LookupBlock (Block);
                        if (local_info != null)
                                target.local_info = clonectx.LookupVariable (local_info);
                }
        }

        /// <summary>
        ///   This represents a reference to a parameter in the intermediate
        ///   representation.
        /// </summary>
        public class ParameterReference : VariableReference {
                readonly ToplevelParameterInfo pi;

                public ParameterReference (ToplevelParameterInfo pi, Location loc)
                {
                        this.pi = pi;
                        this.loc = loc;
                }

                public override bool IsRef {
                        get { return (pi.Parameter.ModFlags & Parameter.Modifier.ISBYREF) != 0; }
                }

                bool HasOutModifier {
                        get { return pi.Parameter.ModFlags == Parameter.Modifier.OUT; }
                }

                public override HoistedVariable GetHoistedVariable (EmitContext ec)
                {
                        return pi.Parameter.HoistedVariableReference;
                }

                //
                // A ref or out parameter is classified as a moveable variable, even 
                // if the argument given for the parameter is a fixed variable
                //              
                public override bool IsFixed {
                        get { return !IsRef; }
                }

                public override string Name {
                        get { return Parameter.Name; }
                }

                public Parameter Parameter {
                        get { return pi.Parameter; }
                }

                public override VariableInfo VariableInfo {
                        get { return pi.VariableInfo; }
                }

                protected override ILocalVariable Variable {
                        get { return Parameter; }
                }

                public bool IsAssigned (EmitContext ec, Location loc)
                {
                        // HACK: Variables are not captured in probing mode
                        if (ec.IsInProbingMode)
                                return true;
                        
                        if (!ec.DoFlowAnalysis || !HasOutModifier || ec.CurrentBranching.IsAssigned (VariableInfo))
                                return true;

                        Report.Error (269, loc, "Use of unassigned out parameter `{0}'", Name);
                        return false;
                }

                public override void SetHasAddressTaken ()
                {
                        Parameter.HasAddressTaken = true;
                }

                void SetAssigned (EmitContext ec)
                {
                        if (HasOutModifier && ec.DoFlowAnalysis)
                                ec.CurrentBranching.SetAssigned (VariableInfo);
                }

                bool DoResolveBase (EmitContext ec)
                {
                        type = pi.ParameterType;
                        eclass = ExprClass.Variable;

                        AnonymousExpression am = ec.CurrentAnonymousMethod;
                        if (am == null)
                                return true;

                        Block b = ec.CurrentBlock;
                        while (b != null) {
                                IParameterData[] p = b.Toplevel.Parameters.FixedParameters;
                                for (int i = 0; i < p.Length; ++i) {
                                        if (p [i] != Parameter)
                                                continue;

                                        //
                                        // Skip closest anonymous method parameters
                                        //
                                        if (b == ec.CurrentBlock && !am.IsIterator)
                                                return true;

                                        if (IsRef) {
                                                Report.Error (1628, loc,
                                                        "Parameter `{0}' cannot be used inside `{1}' when using `ref' or `out' modifier",
                                                        Name, am.ContainerType);
                                        }

                                        b = null;
                                        break;
                                }

                                if (b != null)
                                        b = b.Toplevel.Parent;
                        }

                        if (pi.Parameter.HasAddressTaken)
                                AnonymousMethodExpression.Error_AddressOfCapturedVar (this, loc);

                        if (ec.IsVariableCapturingRequired) {
                                AnonymousMethodStorey storey = pi.Block.CreateAnonymousMethodStorey (ec);
                                storey.CaptureParameter (ec, this);
                        }

                        return true;
                }

                public override int GetHashCode ()
                {
                        return Name.GetHashCode ();
                }

                public override bool Equals (object obj)
                {
                        ParameterReference pr = obj as ParameterReference;
                        if (pr == null)
                                return false;

                        return Name == pr.Name;
                }
                
                protected override void CloneTo (CloneContext clonectx, Expression target)
                {
                        // Nothing to clone
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        HoistedVariable hv = GetHoistedVariable (ec);
                        if (hv != null)
                                return hv.CreateExpressionTree (ec);

                        return Parameter.ExpressionTreeVariableReference ();
                }

                //
                // Notice that for ref/out parameters, the type exposed is not the
                // same type exposed externally.
                //
                // for "ref int a":
                //   externally we expose "int&"
                //   here we expose       "int".
                //
                // We record this in "is_ref".  This means that the type system can treat
                // the type as it is expected, but when we generate the code, we generate
                // the alternate kind of code.
                //
                public override Expression DoResolve (EmitContext ec)
                {
                        if (!DoResolveBase (ec))
                                return null;

                        // HACK: Variables are not captured in probing mode
                        if (ec.IsInProbingMode)
                                return this;

                        if (HasOutModifier && ec.DoFlowAnalysis &&
                            (!ec.OmitStructFlowAnalysis || !VariableInfo.TypeInfo.IsStruct) && !IsAssigned (ec, loc))
                                return null;

                        return this;
                }

                override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        if (!DoResolveBase (ec))
                                return null;

                        // HACK: parameters are not captured when probing is on
                        if (!ec.IsInProbingMode)
                                SetAssigned (ec);

                        return this;
                }

                static public void EmitLdArg (ILGenerator ig, int x)
                {
                        switch (x) {
                        case 0: ig.Emit (OpCodes.Ldarg_0); break;
                        case 1: ig.Emit (OpCodes.Ldarg_1); break;
                        case 2: ig.Emit (OpCodes.Ldarg_2); break;
                        case 3: ig.Emit (OpCodes.Ldarg_3); break;
                        default:
                                if (x > byte.MaxValue)
                                        ig.Emit (OpCodes.Ldarg, x);
                                else
                                        ig.Emit (OpCodes.Ldarg_S, (byte) x);
                                break;
                        }
                }
        }
        
        /// <summary>
        ///   Used for arguments to New(), Invocation()
        /// </summary>
        public class Argument {
                public enum AType : byte {
                        Expression,
                        Ref,
                        Out,
                        ArgList
                };

                public static readonly Argument[] Empty = new Argument [0];

                public readonly AType ArgType;
                public Expression Expr;
                
                public Argument (Expression expr, AType type)
                {
                        this.Expr = expr;
                        this.ArgType = type;
                }

                public Argument (Expression expr)
                {
                        this.Expr = expr;
                        this.ArgType = AType.Expression;
                }

                public Type Type {
                        get { return Expr.Type; }
                }

                public Parameter.Modifier Modifier
                {
                        get {
                                switch (ArgType) {
                                case AType.Out:
                                        return Parameter.Modifier.OUT;
                                        
                                case AType.Ref:
                                        return Parameter.Modifier.REF;
                                        
                                default:
                                        return Parameter.Modifier.NONE;
                                }
                        }
                }

                public string GetSignatureForError ()
                {
                        if (Expr.eclass == ExprClass.MethodGroup)
                                return Expr.ExprClassName;

                        return TypeManager.CSharpName (Expr.Type);
                }               

                public bool ResolveMethodGroup (EmitContext ec)
                {
                        SimpleName sn = Expr as SimpleName;
                        if (sn != null)
                                Expr = sn.GetMethodGroup ();

                        // FIXME: csc doesn't report any error if you try to use `ref' or
                        //        `out' in a delegate creation expression.
                        Expr = Expr.Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
                        if (Expr == null)
                                return false;

                        return true;
                }

                public bool Resolve (EmitContext ec, Location loc)
                {
                        if (Expr == null)
                                return false;

                        using (ec.With (EmitContext.Flags.DoFlowAnalysis, true)) {
                                // Verify that the argument is readable
                                if (ArgType != AType.Out)
                                        Expr = Expr.Resolve (ec);

                                // Verify that the argument is writeable
                                if (Expr != null && (ArgType == AType.Out || ArgType == AType.Ref))
                                        Expr = Expr.ResolveLValue (ec, EmptyExpression.OutAccess, loc);

                                return Expr != null;
                        }
                }

                public void Emit (EmitContext ec)
                {
                        if (ArgType != AType.Ref && ArgType != AType.Out) {
                                Expr.Emit (ec);
                                return;
                        }

                        AddressOp mode = AddressOp.Store;
                        if (ArgType == AType.Ref)
                                mode |= AddressOp.Load;
                                
                        IMemoryLocation ml = (IMemoryLocation) Expr;
                        ParameterReference pr = ml as ParameterReference;

                        //
                        // ParameterReferences might already be references, so we want
                        // to pass just the value
                        //
                        if (pr != null && pr.IsRef)
                                pr.EmitLoad (ec);
                        else
                                ml.AddressOf (ec, mode);
                }

                public Argument Clone (CloneContext clonectx)
                {
                        return new Argument (Expr.Clone (clonectx), ArgType);
                }
        }

        /// <summary>
        ///   Invocation of methods or delegates.
        /// </summary>
        public class Invocation : ExpressionStatement {
                protected ArrayList Arguments;
                protected Expression expr;
                protected MethodGroupExpr mg;
                bool arguments_resolved;
                
                //
                // arguments is an ArrayList, but we do not want to typecast,
                // as it might be null.
                //
                public Invocation (Expression expr, ArrayList arguments)
                {
                        SimpleName sn = expr as SimpleName;
                        if (sn != null)
                                this.expr = sn.GetMethodGroup ();
                        else
                                this.expr = expr;
                        
                        Arguments = arguments;
                        if (expr != null)
                                loc = expr.Location;
                }

                public Invocation (Expression expr, ArrayList arguments, bool arguments_resolved)
                        : this (expr, arguments)
                {
                        this.arguments_resolved = arguments_resolved;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args;

                        //
                        // Special conversion for nested expression trees
                        //
                        if (TypeManager.DropGenericTypeArguments (type) == TypeManager.expression_type) {
                                args = new ArrayList (1);
                                args.Add (new Argument (this));
                                return CreateExpressionFactoryCall ("Quote", args);
                        }

                        ExtensionMethodGroupExpr emg = mg as ExtensionMethodGroupExpr;

                        int arg_count = Arguments == null ? 2 : Arguments.Count + 2;
                        if (emg != null)
                                ++arg_count;
                        args = new ArrayList (arg_count);

                        if (mg.IsInstance)
                                args.Add (new Argument (mg.InstanceExpression.CreateExpressionTree (ec)));
                        else
                                args.Add (new Argument (new NullLiteral (loc)));

                        args.Add (new Argument (mg.CreateExpressionTree (ec)));

                        //
                        // Use extension argument when exists
                        //
                        if (emg != null) {
                                Expression e = emg.ExtensionExpression.CreateExpressionTree (ec);
                                if (e != null)
                                        args.Add (new Argument (e));
                        }

                        if (Arguments != null) {
                                foreach (Argument a in Arguments) {
                                        Expression e = a.Expr.CreateExpressionTree (ec);
                                        if (e != null)
                                                args.Add (new Argument (e));
                                }
                        }

                        if (mg.IsBase)
                                MemberExpr.Error_BaseAccessInExpressionTree (loc);

                        return CreateExpressionFactoryCall ("Call", args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        // Don't resolve already resolved expression
                        if (eclass != ExprClass.Invalid)
                                return this;
                        
                        Expression expr_resolved = expr.Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
                        if (expr_resolved == null)
                                return null;

                        mg = expr_resolved as MethodGroupExpr;
                        if (mg == null) {
                                Type expr_type = expr_resolved.Type;

                                if (expr_type != null && TypeManager.IsDelegateType (expr_type)){
                                        return (new DelegateInvocation (
                                                expr_resolved, Arguments, loc)).Resolve (ec);
                                }

                                MemberExpr me = expr_resolved as MemberExpr;
                                if (me == null) {
                                        expr_resolved.Error_UnexpectedKind (ResolveFlags.MethodGroup, loc);
                                        return null;
                                }
                                
                                mg = ec.TypeContainer.LookupExtensionMethod (me.Type, me.Name, loc);
                                if (mg == null) {
                                        Report.Error (1955, loc, "The member `{0}' cannot be used as method or delegate",
                                                expr_resolved.GetSignatureForError ());
                                        return null;
                                }

                                ((ExtensionMethodGroupExpr)mg).ExtensionExpression = me.InstanceExpression;
                        }

                        //
                        // Next, evaluate all the expressions in the argument list
                        //
                        if (Arguments != null && !arguments_resolved) {
                                for (int i = 0; i < Arguments.Count; ++i)
                                {
                                        if (!((Argument)Arguments[i]).Resolve(ec, loc))
                                                return null;
                                }
                        }

                        mg = DoResolveOverload (ec);
                        if (mg == null)
                                return null;

                        MethodInfo method = (MethodInfo)mg;
                        if (method != null) {
                                type = TypeManager.TypeToCoreType (method.ReturnType);

                                // TODO: this is a copy of mg.ResolveMemberAccess method
                                Expression iexpr = mg.InstanceExpression;
                                if (method.IsStatic) {
                                        if (iexpr == null ||
                                                iexpr is This || iexpr is EmptyExpression ||
                                                mg.IdenticalTypeName) {
                                                mg.InstanceExpression = null;
                                        } else {
                                                MemberExpr.error176 (loc, mg.GetSignatureForError ());
                                                return null;
                                        }
                                } else {
                                        if (iexpr == null || iexpr == EmptyExpression.Null) {
                                                SimpleName.Error_ObjectRefRequired (ec, loc, mg.GetSignatureForError ());
                                        }
                                }
                        }

                        if (type.IsPointer){
                                if (!ec.InUnsafe){
                                        UnsafeError (loc);
                                        return null;
                                }
                        }
                        
                        //
                        // Only base will allow this invocation to happen.
                        //
                        if (mg.IsBase && method.IsAbstract){
                                Error_CannotCallAbstractBase (TypeManager.CSharpSignature (method));
                                return null;
                        }

                        if (Arguments == null && method.DeclaringType == TypeManager.object_type && method.Name == Destructor.MetadataName) {
                                if (mg.IsBase)
                                        Report.Error (250, loc, "Do not directly call your base class Finalize method. It is called automatically from your destructor");
                                else
                                        Report.Error (245, loc, "Destructors and object.Finalize cannot be called directly. Consider calling IDisposable.Dispose if available");
                                return null;
                        }

                        IsSpecialMethodInvocation (method, loc);
                        
                        if (mg.InstanceExpression != null)
                                mg.InstanceExpression.CheckMarshalByRefAccess (ec);

                        eclass = ExprClass.Value;
                        return this;
                }

                protected virtual MethodGroupExpr DoResolveOverload (EmitContext ec)
                {
                        return mg.OverloadResolve (ec, ref Arguments, false, loc);
                }

                public static bool IsSpecialMethodInvocation (MethodBase method, Location loc)
                {
                        if (!TypeManager.IsSpecialMethod (method))
                                return false;

                        Report.SymbolRelatedToPreviousError (method);
                        Report.Error (571, loc, "`{0}': cannot explicitly call operator or accessor",
                                TypeManager.CSharpSignature (method, true));
        
                        return true;
                }

                /// <summary>
                ///   Emits a list of resolved Arguments that are in the arguments
                ///   ArrayList.
                /// 
                ///   The MethodBase argument might be null if the
                ///   emission of the arguments is known not to contain
                ///   a `params' field (for example in constructors or other routines
                ///   that keep their arguments in this structure)
                ///   
                ///   if `dup_args' is true, a copy of the arguments will be left
                ///   on the stack. If `dup_args' is true, you can specify `this_arg'
                ///   which will be duplicated before any other args. Only EmitCall
                ///   should be using this interface.
                /// </summary>
                public static void EmitArguments (EmitContext ec, ArrayList arguments, bool dup_args, LocalTemporary this_arg)
                {
                        if (arguments == null)
                                return;

                        int top = arguments.Count;
                        LocalTemporary [] temps = null;
                        
                        if (dup_args && top != 0)
                                temps = new LocalTemporary [top];

                        int argument_index = 0;
                        Argument a;
                        for (int i = 0; i < top; i++) {
                                a = (Argument) arguments [argument_index++];
                                a.Emit (ec);
                                if (dup_args) {
                                        ec.ig.Emit (OpCodes.Dup);
                                        (temps [i] = new LocalTemporary (a.Type)).Store (ec);
                                }
                        }
                        
                        if (dup_args) {
                                if (this_arg != null)
                                        this_arg.Emit (ec);
                                
                                for (int i = 0; i < top; i ++) {
                                        temps [i].Emit (ec);
                                        temps [i].Release (ec);
                                }
                        }
                }

                static Type[] GetVarargsTypes (MethodBase mb, ArrayList arguments)
                {
                        AParametersCollection pd = TypeManager.GetParameterData (mb);
                        
                        Argument a = (Argument) arguments [pd.Count - 1];
                        Arglist list = (Arglist) a.Expr;

                        return list.ArgumentTypes;
                }

                /// <summary>
                /// This checks the ConditionalAttribute on the method 
                /// </summary>
                public static bool IsMethodExcluded (MethodBase method, Location loc)
                {
                        if (method.IsConstructor)
                                return false;

                        method = TypeManager.DropGenericMethodArguments (method);
                        if (method.DeclaringType.Module == RootContext.ToplevelTypes.Builder) {
                                IMethodData md = TypeManager.GetMethod (method);
                                if (md != null)
                                        return md.IsExcluded ();

                                // For some methods (generated by delegate class) GetMethod returns null
                                // because they are not included in builder_to_method table
                                return false;
                        }

                        return AttributeTester.IsConditionalMethodExcluded (method, loc);
                }

                /// <remarks>
                ///   is_base tells whether we want to force the use of the `call'
                ///   opcode instead of using callvirt.  Call is required to call
                ///   a specific method, while callvirt will always use the most
                ///   recent method in the vtable.
                ///
                ///   is_static tells whether this is an invocation on a static method
                ///
                ///   instance_expr is an expression that represents the instance
                ///   it must be non-null if is_static is false.
                ///
                ///   method is the method to invoke.
                ///
                ///   Arguments is the list of arguments to pass to the method or constructor.
                /// </remarks>
                public static void EmitCall (EmitContext ec, bool is_base,
                                             Expression instance_expr,
                                             MethodBase method, ArrayList Arguments, Location loc)
                {
                        EmitCall (ec, is_base, instance_expr, method, Arguments, loc, false, false);
                }
                
                // `dup_args' leaves an extra copy of the arguments on the stack
                // `omit_args' does not leave any arguments at all.
                // So, basically, you could make one call with `dup_args' set to true,
                // and then another with `omit_args' set to true, and the two calls
                // would have the same set of arguments. However, each argument would
                // only have been evaluated once.
                public static void EmitCall (EmitContext ec, bool is_base,
                                             Expression instance_expr,
                                             MethodBase method, ArrayList Arguments, Location loc,
                                             bool dup_args, bool omit_args)
                {
                        ILGenerator ig = ec.ig;
                        bool struct_call = false;
                        bool this_call = false;
                        LocalTemporary this_arg = null;

                        Type decl_type = method.DeclaringType;

                        if (IsMethodExcluded (method, loc))
                                return;
                        
                        bool is_static = method.IsStatic;
                        if (!is_static){
                                this_call = instance_expr is This;
                                if (TypeManager.IsStruct (decl_type) || TypeManager.IsEnumType (decl_type))
                                        struct_call = true;

                                //
                                // If this is ourselves, push "this"
                                //
                                if (!omit_args) {
                                        Type t = null;
                                        Type iexpr_type = instance_expr.Type;

                                        //
                                        // Push the instance expression
                                        //
                                        if (TypeManager.IsValueType (iexpr_type) || TypeManager.IsGenericParameter (iexpr_type)) {
                                                //
                                                // Special case: calls to a function declared in a 
                                                // reference-type with a value-type argument need
                                                // to have their value boxed.
                                                if (TypeManager.IsStruct (decl_type) ||
                                                    TypeManager.IsGenericParameter (iexpr_type)) {
                                                        //
                                                        // If the expression implements IMemoryLocation, then
                                                        // we can optimize and use AddressOf on the
                                                        // return.
                                                        //
                                                        // If not we have to use some temporary storage for
                                                        // it.
                                                        if (instance_expr is IMemoryLocation) {
                                                                ((IMemoryLocation)instance_expr).
                                                                        AddressOf (ec, AddressOp.LoadStore);
                                                        } else {
                                                                LocalTemporary temp = new LocalTemporary (iexpr_type);
                                                                instance_expr.Emit (ec);
                                                                temp.Store (ec);
                                                                temp.AddressOf (ec, AddressOp.Load);
                                                        }

                                                        // avoid the overhead of doing this all the time.
                                                        if (dup_args)
                                                                t = TypeManager.GetReferenceType (iexpr_type);
                                                } else {
                                                        instance_expr.Emit (ec);
                                                        
                                                        // FIXME: should use instance_expr is IMemoryLocation + constraint.
                                                        // to help JIT to produce better code
                                                        ig.Emit (OpCodes.Box, instance_expr.Type);
                                                        t = TypeManager.object_type;
                                                }
                                        } else {
                                                instance_expr.Emit (ec);
                                                t = instance_expr.Type;
                                        }

                                        if (dup_args) {
                                                ig.Emit (OpCodes.Dup);
                                                if (Arguments != null && Arguments.Count != 0) {
                                                        this_arg = new LocalTemporary (t);
                                                        this_arg.Store (ec);
                                                }
                                        }
                                }
                        }

                        if (!omit_args)
                                EmitArguments (ec, Arguments, dup_args, this_arg);

                        OpCode call_op;
                        if (is_static || struct_call || is_base || (this_call && !method.IsVirtual)) {
                                call_op = OpCodes.Call;
                        } else {
                                call_op = OpCodes.Callvirt;
                                
#if GMCS_SOURCE
                                if ((instance_expr != null) && (instance_expr.Type.IsGenericParameter))
                                        ig.Emit (OpCodes.Constrained, instance_expr.Type);
#endif
                        }

                        if ((method.CallingConvention & CallingConventions.VarArgs) != 0) {
                                Type[] varargs_types = GetVarargsTypes (method, Arguments);
                                ig.EmitCall (call_op, (MethodInfo) method, varargs_types);
                                return;
                        }

                        //
                        // If you have:
                        // this.DoFoo ();
                        // and DoFoo is not virtual, you can omit the callvirt,
                        // because you don't need the null checking behavior.
                        //
                        if (method is MethodInfo)
                                ig.Emit (call_op, (MethodInfo) method);
                        else
                                ig.Emit (call_op, (ConstructorInfo) method);
                }

                public override void Emit (EmitContext ec)
                {
                        mg.EmitCall (ec, Arguments);
                }
                
                public override void EmitStatement (EmitContext ec)
                {
                        Emit (ec);

                        // 
                        // Pop the return value if there is one
                        //
                        if (TypeManager.TypeToCoreType (type) != TypeManager.void_type)
                                ec.ig.Emit (OpCodes.Pop);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Invocation target = (Invocation) t;

                        if (Arguments != null) {
                                target.Arguments = new ArrayList (Arguments.Count);
                                foreach (Argument a in Arguments)
                                        target.Arguments.Add (a.Clone (clonectx));
                        }

                        target.expr = expr.Clone (clonectx);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        mg.MutateHoistedGenericType (storey);
                        if (Arguments != null) {
                                foreach (Argument a in Arguments)
                                        a.Expr.MutateHoistedGenericType (storey);
                        }
                }
        }
/*
        //
        // It's either a cast or delegate invocation
        //
        public class InvocationOrCast : ExpressionStatement
        {
                Expression expr;
                Expression argument;

                public InvocationOrCast (Expression expr, Expression argument)
                {
                        this.expr = expr;
                        this.argument = argument;
                        this.loc = expr.Location;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        Expression e = ResolveCore (ec);
                        if (e == null)
                                return null;

                        return e.Resolve (ec);
                }

                Expression ResolveCore (EmitContext ec)
                {
                        //
                        // First try to resolve it as a cast.
                        //
                        TypeExpr te = expr.ResolveAsBaseTerminal (ec, true);
                        if (te != null) {
                                return new Cast (te, argument, loc);
                        }

                        //
                        // This can either be a type or a delegate invocation.
                        // Let's just resolve it and see what we'll get.
                        //
                        expr = expr.Resolve (ec, ResolveFlags.Type | ResolveFlags.VariableOrValue);
                        if (expr == null)
                                return null;

                        //
                        // Ok, so it's a Cast.
                        //
                        if (expr.eclass == ExprClass.Type || expr.eclass == ExprClass.TypeParameter) {
                                return new Cast (expr, argument, loc);
                        }

                        if (expr.eclass == ExprClass.Namespace) {
                                expr.Error_UnexpectedKind (null, "type", loc);
                                return null;
                        }                       

                        //
                        // It's a delegate invocation.
                        //
                        if (!TypeManager.IsDelegateType (expr.Type)) {
                                Error (149, "Method name expected");
                                return null;
                        }

                        ArrayList args = new ArrayList (1);
                        args.Add (new Argument (argument, Argument.AType.Expression));
                        return new DelegateInvocation (expr, args, loc);
                }

                public override ExpressionStatement ResolveStatement (EmitContext ec)
                {
                        Expression e = ResolveCore (ec);
                        if (e == null)
                                return null;

                        ExpressionStatement s = e as ExpressionStatement;
                        if (s == null) {
                                Error_InvalidExpressionStatement ();
                                return null;
                        }

                        return s.ResolveStatement (ec);
                }

                public override void Emit (EmitContext ec)
                {
                        throw new Exception ("Cannot happen");
                }

                public override void EmitStatement (EmitContext ec)
                {
                        throw new Exception ("Cannot happen");
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        InvocationOrCast target = (InvocationOrCast) t;

                        target.expr = expr.Clone (clonectx);
                        target.argument = argument.Clone (clonectx);
                }
        }
*/

        /// <summary>
        ///    Implements the new expression 
        /// </summary>
        public class New : ExpressionStatement, IMemoryLocation {
                ArrayList Arguments;

                //
                // During bootstrap, it contains the RequestedType,
                // but if `type' is not null, it *might* contain a NewDelegate
                // (because of field multi-initialization)
                //
                Expression RequestedType;

                MethodGroupExpr method;

                bool is_type_parameter;
                
                public New (Expression requested_type, ArrayList arguments, Location l)
                {
                        RequestedType = requested_type;
                        Arguments = arguments;
                        loc = l;
                }

                /// <summary>
                /// Converts complex core type syntax like 'new int ()' to simple constant
                /// </summary>
                public static Constant Constantify (Type t)
                {
                        if (t == TypeManager.int32_type)
                                return new IntConstant (0, Location.Null);
                        if (t == TypeManager.uint32_type)
                                return new UIntConstant (0, Location.Null);
                        if (t == TypeManager.int64_type)
                                return new LongConstant (0, Location.Null);
                        if (t == TypeManager.uint64_type)
                                return new ULongConstant (0, Location.Null);
                        if (t == TypeManager.float_type)
                                return new FloatConstant (0, Location.Null);
                        if (t == TypeManager.double_type)
                                return new DoubleConstant (0, Location.Null);
                        if (t == TypeManager.short_type)
                                return new ShortConstant (0, Location.Null);
                        if (t == TypeManager.ushort_type)
                                return new UShortConstant (0, Location.Null);
                        if (t == TypeManager.sbyte_type)
                                return new SByteConstant (0, Location.Null);
                        if (t == TypeManager.byte_type)
                                return new ByteConstant (0, Location.Null);
                        if (t == TypeManager.char_type)
                                return new CharConstant ('\0', Location.Null);
                        if (t == TypeManager.bool_type)
                                return new BoolConstant (false, Location.Null);
                        if (t == TypeManager.decimal_type)
                                return new DecimalConstant (0, Location.Null);
                        if (TypeManager.IsEnumType (t))
                                return new EnumConstant (Constantify (TypeManager.GetEnumUnderlyingType (t)), t);
                        if (TypeManager.IsNullableType (t))
                                return Nullable.LiftedNull.Create (t, Location.Null);

                        return null;
                }

                //
                // Checks whether the type is an interface that has the
                // [ComImport, CoClass] attributes and must be treated
                // specially
                //
                public Expression CheckComImport (EmitContext ec)
                {
                        if (!type.IsInterface)
                                return null;

                        //
                        // Turn the call into:
                        // (the-interface-stated) (new class-referenced-in-coclassattribute ())
                        //
                        Type real_class = AttributeTester.GetCoClassAttribute (type);
                        if (real_class == null)
                                return null;

                        New proxy = new New (new TypeExpression (real_class, loc), Arguments, loc);
                        Cast cast = new Cast (new TypeExpression (type, loc), proxy, loc);
                        return cast.Resolve (ec);
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = Arguments == null ?
                                new ArrayList (1) : new ArrayList (Arguments.Count + 1);

                        if (method == null) {
                                args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
                        } else {
                                args.Add (new Argument (method.CreateExpressionTree (ec)));
                                if (Arguments != null) {
                                        Expression expr;
                                        foreach (Argument a in Arguments) {
                                                expr = a.Expr.CreateExpressionTree (ec);
                                                if (expr != null)
                                                        args.Add (new Argument (expr));
                                        }
                                }
                        }

                        return CreateExpressionFactoryCall ("New", args);
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        //
                        // The New DoResolve might be called twice when initializing field
                        // expressions (see EmitFieldInitializers, the call to
                        // GetInitializerExpression will perform a resolve on the expression,
                        // and later the assign will trigger another resolution
                        //
                        // This leads to bugs (#37014)
                        //
                        if (type != null){
                                if (RequestedType is NewDelegate)
                                        return RequestedType;
                                return this;
                        }

                        TypeExpr texpr = RequestedType.ResolveAsTypeTerminal (ec, false);
                        if (texpr == null)
                                return null;

                        type = texpr.Type;

                        if (type.IsPointer) {
                                Report.Error (1919, loc, "Unsafe type `{0}' cannot be used in an object creation expression",
                                        TypeManager.CSharpName (type));
                                return null;
                        }

                        if (Arguments == null) {
                                Constant c = Constantify (type);
                                if (c != null)
                                        return ReducedExpression.Create (c, this);
                        }

                        if (TypeManager.IsDelegateType (type)) {
                                return (new NewDelegate (type, Arguments, loc)).Resolve (ec);
                        }

                        if (TypeManager.IsGenericParameter (type)) {
                                GenericConstraints gc = TypeManager.GetTypeParameterConstraints (type);

                                if ((gc == null) || (!gc.HasConstructorConstraint && !gc.IsValueType)) {
                                        Error (304, String.Format (
                                                       "Cannot create an instance of the " +
                                                       "variable type '{0}' because it " +
                                                       "doesn't have the new() constraint",
                                                       type));
                                        return null;
                                }

                                if ((Arguments != null) && (Arguments.Count != 0)) {
                                        Error (417, String.Format (
                                                       "`{0}': cannot provide arguments " +
                                                       "when creating an instance of a " +
                                                       "variable type.", type));
                                        return null;
                                }

                                if (TypeManager.activator_create_instance == null) {
                                        Type activator_type = TypeManager.CoreLookupType ("System", "Activator", Kind.Class, true);
                                        if (activator_type != null) {
                                                TypeManager.activator_create_instance = TypeManager.GetPredefinedMethod (
                                                        activator_type, "CreateInstance", loc, Type.EmptyTypes);
                                        }
                                }

                                is_type_parameter = true;
                                eclass = ExprClass.Value;
                                return this;
                        }

                        if (type.IsAbstract && type.IsSealed) {
                                Report.SymbolRelatedToPreviousError (type);
                                Report.Error (712, loc, "Cannot create an instance of the static class `{0}'", TypeManager.CSharpName (type));
                                return null;
                        }

                        if (type.IsInterface || type.IsAbstract){
                                if (!TypeManager.IsGenericType (type)) {
                                        RequestedType = CheckComImport (ec);
                                        if (RequestedType != null)
                                                return RequestedType;
                                }
                                
                                Report.SymbolRelatedToPreviousError (type);
                                Report.Error (144, loc, "Cannot create an instance of the abstract class or interface `{0}'", TypeManager.CSharpName (type));
                                return null;
                        }

                        bool is_struct = TypeManager.IsStruct (type);
                        eclass = ExprClass.Value;

                        //
                        // SRE returns a match for .ctor () on structs (the object constructor), 
                        // so we have to manually ignore it.
                        //
                        if (is_struct && Arguments == null)
                                return this;

                        // For member-lookup, treat 'new Foo (bar)' as call to 'foo.ctor (bar)', where 'foo' is of type 'Foo'.
                        Expression ml = MemberLookupFinal (ec, type, type, ".ctor",
                                MemberTypes.Constructor, AllBindingFlags | BindingFlags.DeclaredOnly, loc);

                        if (Arguments != null){
                                foreach (Argument a in Arguments){
                                        if (!a.Resolve (ec, loc))
                                                return null;
                                }
                        }

                        if (ml == null)
                                return null;

                        method = ml as MethodGroupExpr;
                        if (method == null) {
                                ml.Error_UnexpectedKind (ec.DeclContainer, "method group", loc);
                                return null;
                        }

                        method = method.OverloadResolve (ec, ref Arguments, false, loc);
                        if (method == null)
                                return null;

                        return this;
                }

                bool DoEmitTypeParameter (EmitContext ec)
                {
#if GMCS_SOURCE
                        ILGenerator ig = ec.ig;
//                      IMemoryLocation ml;

                        MethodInfo ci = TypeManager.activator_create_instance.MakeGenericMethod (
                                new Type [] { type });

                        GenericConstraints gc = TypeManager.GetTypeParameterConstraints (type);
                        if (gc.HasReferenceTypeConstraint || gc.HasClassConstraint) {
                                ig.Emit (OpCodes.Call, ci);
                                return true;
                        }

                        // Allow DoEmit() to be called multiple times.
                        // We need to create a new LocalTemporary each time since
                        // you can't share LocalBuilders among ILGeneators.
                        LocalTemporary temp = new LocalTemporary (type);

                        Label label_activator = ig.DefineLabel ();
                        Label label_end = ig.DefineLabel ();

                        temp.AddressOf (ec, AddressOp.Store);
                        ig.Emit (OpCodes.Initobj, type);

                        temp.Emit (ec);
                        ig.Emit (OpCodes.Box, type);
                        ig.Emit (OpCodes.Brfalse, label_activator);

                        temp.AddressOf (ec, AddressOp.Store);
                        ig.Emit (OpCodes.Initobj, type);
                        temp.Emit (ec);
                        ig.Emit (OpCodes.Br_S, label_end);

                        ig.MarkLabel (label_activator);

                        ig.Emit (OpCodes.Call, ci);
                        ig.MarkLabel (label_end);
                        return true;
#else
                        throw new InternalErrorException ();
#endif
                }

                //
                // This Emit can be invoked in two contexts:
                //    * As a mechanism that will leave a value on the stack (new object)
                //    * As one that wont (init struct)
                //
                // If we are dealing with a ValueType, we have a few
                // situations to deal with:
                //
                //    * The target is a ValueType, and we have been provided
                //      the instance (this is easy, we are being assigned).
                //
                //    * The target of New is being passed as an argument,
                //      to a boxing operation or a function that takes a
                //      ValueType.
                //
                //      In this case, we need to create a temporary variable
                //      that is the argument of New.
                //
                // Returns whether a value is left on the stack
                //
                // *** Implementation note ***
                //
                // To benefit from this optimization, each assignable expression
                // has to manually cast to New and call this Emit.
                //
                // TODO: It's worth to implement it for arrays and fields
                //
                public virtual bool Emit (EmitContext ec, IMemoryLocation target)
                {
                        bool is_value_type = TypeManager.IsValueType (type);
                        ILGenerator ig = ec.ig;
                        VariableReference vr = target as VariableReference;

                        if (target != null && is_value_type && (vr != null || method == null)) {
                                target.AddressOf (ec, AddressOp.Store);
                        } else if (vr != null && vr.IsRef) {
                                vr.EmitLoad (ec);
                        }
                        
                        if (is_type_parameter)
                                return DoEmitTypeParameter (ec);

                        if (method != null)
                                method.EmitArguments (ec, Arguments);

                        if (is_value_type) {
                                if (method == null) {
                                        ig.Emit (OpCodes.Initobj, type);
                                        return false;
                                }

                                if (vr != null) {
                                        ig.Emit (OpCodes.Call, (ConstructorInfo) method);
                                        return false;
                                }
                        }

                        ConstructorInfo ci = (ConstructorInfo) method;
#if MS_COMPATIBLE
                        if (TypeManager.IsGenericType (type))
                                ci = TypeBuilder.GetConstructor (type, ci);
#endif

                        ig.Emit (OpCodes.Newobj, ci);
                        return true;
                }

                public override void Emit (EmitContext ec)
                {
                        LocalTemporary v = null;
                        if (method == null && TypeManager.IsValueType (type)) {
                                // TODO: Use temporary variable from pool
                                v = new LocalTemporary (type);
                        }

                        if (!Emit (ec, v))
                                v.Emit (ec);
                }
                
                public override void EmitStatement (EmitContext ec)
                {
                        LocalTemporary v = null;
                        if (method == null && TypeManager.IsValueType (type)) {
                                // TODO: Use temporary variable from pool
                                v = new LocalTemporary (type);
                        }

                        if (Emit (ec, v))
                                ec.ig.Emit (OpCodes.Pop);
                }

                public virtual bool HasInitializer {
                        get {
                                return false;
                        }
                }

                public void AddressOf (EmitContext ec, AddressOp mode)
                {
                        EmitAddressOf (ec, mode);
                }

                protected virtual IMemoryLocation EmitAddressOf (EmitContext ec, AddressOp mode)
                {
                        LocalTemporary value_target = new LocalTemporary (type);

                        if (is_type_parameter) {
                                DoEmitTypeParameter (ec);
                                value_target.Store (ec);
                                value_target.AddressOf (ec, mode);
                                return value_target;
                        }

                        if (!TypeManager.IsStruct (type)){
                                //
                                // We throw an exception.  So far, I believe we only need to support
                                // value types:
                                // foreach (int j in new StructType ())
                                // see bug 42390
                                //
                                throw new Exception ("AddressOf should not be used for classes");
                        }

                        value_target.AddressOf (ec, AddressOp.Store);

                        if (method == null) {
                                ec.ig.Emit (OpCodes.Initobj, type);
                        } else {
                                method.EmitArguments (ec, Arguments);
                                ec.ig.Emit (OpCodes.Call, (ConstructorInfo) method);
                        }
                        
                        value_target.AddressOf (ec, mode);
                        return value_target;
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        New target = (New) t;

                        target.RequestedType = RequestedType.Clone (clonectx);
                        if (Arguments != null){
                                target.Arguments = new ArrayList ();
                                foreach (Argument a in Arguments){
                                        target.Arguments.Add (a.Clone (clonectx));
                                }
                        }
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        if (method != null) {
                                method.MutateHoistedGenericType (storey);
                                if (Arguments != null) {
                                        foreach (Argument a in Arguments)
                                                a.Expr.MutateHoistedGenericType (storey);
                                }
                        }

                        type = storey.MutateType (type);
                }
        }

        /// <summary>
        ///   14.5.10.2: Represents an array creation expression.
        /// </summary>
        ///
        /// <remarks>
        ///   There are two possible scenarios here: one is an array creation
        ///   expression that specifies the dimensions and optionally the
        ///   initialization data and the other which does not need dimensions
        ///   specified but where initialization data is mandatory.
        /// </remarks>
        public class ArrayCreation : Expression {
                FullNamedExpression requested_base_type;
                ArrayList initializers;

                //
                // The list of Argument types.
                // This is used to construct the `newarray' or constructor signature
                //
                protected ArrayList arguments;
                
                protected Type array_element_type;
                bool expect_initializers = false;
                int num_arguments = 0;
                protected int dimensions;
                protected readonly string rank;

                protected ArrayList array_data;

                IDictionary bounds;

                // The number of constants in array initializers
                int const_initializers_count;
                bool only_constant_initializers;
                
                public ArrayCreation (FullNamedExpression requested_base_type, ArrayList exprs, string rank, ArrayList initializers, Location l)
                {
                        this.requested_base_type = requested_base_type;
                        this.initializers = initializers;
                        this.rank = rank;
                        loc = l;

                        arguments = new ArrayList (exprs.Count);

                        foreach (Expression e in exprs) {
                                arguments.Add (new Argument (e, Argument.AType.Expression));
                                num_arguments++;
                        }
                }

                public ArrayCreation (FullNamedExpression requested_base_type, string rank, ArrayList initializers, Location l)
                {
                        this.requested_base_type = requested_base_type;
                        this.initializers = initializers;
                        this.rank = rank;
                        loc = l;

                        //this.rank = rank.Substring (0, rank.LastIndexOf ('['));
                        //
                        //string tmp = rank.Substring (rank.LastIndexOf ('['));
                        //
                        //dimensions = tmp.Length - 1;
                        expect_initializers = true;
                }

                public static void Error_IncorrectArrayInitializer (Location loc)
                {
                        Report.Error (178, loc, "Invalid rank specifier: expected `,' or `]'");
                }

                protected override void Error_NegativeArrayIndex (Location loc)
                {
                        Report.Error (248, loc, "Cannot create an array with a negative size");
                }
                
                bool CheckIndices (EmitContext ec, ArrayList probe, int idx, bool specified_dims)
                {
                        if (specified_dims) { 
                                Argument a = (Argument) arguments [idx];

                                if (!a.Resolve (ec, loc))
                                        return false;

                                Constant c = a.Expr as Constant;
                                if (c != null) {
                                        c = c.ImplicitConversionRequired (ec, TypeManager.int32_type, a.Expr.Location);
                                }

                                if (c == null) {
                                        Report.Error (150, a.Expr.Location, "A constant value is expected");
                                        return false;
                                }

                                int value = (int) c.GetValue ();
                                
                                if (value != probe.Count) {
                                        Error_IncorrectArrayInitializer (loc);
                                        return false;
                                }
                                
                                bounds [idx] = value;
                        }

                        int child_bounds = -1;
                        only_constant_initializers = true;
                        for (int i = 0; i < probe.Count; ++i) {
                                object o = probe [i];
                                if (o is ArrayList) {
                                        ArrayList sub_probe = o as ArrayList;
                                        int current_bounds = sub_probe.Count;
                                        
                                        if (child_bounds == -1) 
                                                child_bounds = current_bounds;

                                        else if (child_bounds != current_bounds){
                                                Error_IncorrectArrayInitializer (loc);
                                                return false;
                                        }
                                        if (idx + 1 >= dimensions){
                                                Error (623, "Array initializers can only be used in a variable or field initializer. Try using a new expression instead");
                                                return false;
                                        }
                                        
                                        bool ret = CheckIndices (ec, sub_probe, idx + 1, specified_dims);
                                        if (!ret)
                                                return false;
                                } else {
                                        if (child_bounds != -1){
                                                Error_IncorrectArrayInitializer (loc);
                                                return false;
                                        }
                                        
                                        Expression element = ResolveArrayElement (ec, (Expression) o);
                                        if (element == null)
                                                continue;

                                        // Initializers with the default values can be ignored
                                        Constant c = element as Constant;
                                        if (c != null) {
                                                if (c.IsDefaultInitializer (array_element_type)) {
                                                        element = null;
                                                }
                                                else {
                                                        ++const_initializers_count;
                                                }
                                        } else {
                                                only_constant_initializers = false;
                                        }
                                        
                                        array_data.Add (element);
                                }
                        }

                        return true;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args;

                        if (array_data == null) {
                                args = new ArrayList (arguments.Count + 1);
                                args.Add (new Argument (new TypeOf (new TypeExpression (array_element_type, loc), loc)));
                                foreach (Argument a in arguments) {
                                        if (arguments.Count == 1) {
                                                Constant c = a.Expr as Constant;
                                                if (c.IsDefaultValue)
                                                        return CreateExpressionFactoryCall ("NewArrayInit", args);
                                        }
                                        args.Add (new Argument (a.Expr.CreateExpressionTree (ec)));
                                }

                                return CreateExpressionFactoryCall ("NewArrayBounds", args);
                        }

                        if (dimensions > 1) {
                                Report.Error (838, loc, "An expression tree cannot contain a multidimensional array initializer");
                                return null;
                        }

                        args = new ArrayList (array_data == null ? 1 : array_data.Count + 1);
                        args.Add (new Argument (new TypeOf (new TypeExpression (array_element_type, loc), loc)));
                        if (array_data != null) {
                                for (int i = 0; i < array_data.Count; ++i) {
                                        Expression e = (Expression) array_data [i];
                                        if (e == null)
                                                e = Convert.ImplicitConversion (ec, (Expression) initializers [i], array_element_type, loc);

                                        args.Add (new Argument (e.CreateExpressionTree (ec)));
                                }
                        }

                        return CreateExpressionFactoryCall ("NewArrayInit", args);
                }               
                
                public void UpdateIndices ()
                {
                        int i = 0;
                        for (ArrayList probe = initializers; probe != null;) {
                                if (probe.Count > 0 && probe [0] is ArrayList) {
                                        Expression e = new IntConstant (probe.Count, Location.Null);
                                        arguments.Add (new Argument (e, Argument.AType.Expression));

                                        bounds [i++] =  probe.Count;
                                        
                                        probe = (ArrayList) probe [0];
                                        
                                } else {
                                        Expression e = new IntConstant (probe.Count, Location.Null);
                                        arguments.Add (new Argument (e, Argument.AType.Expression));

                                        bounds [i++] = probe.Count;
                                        return;
                                }
                        }

                }

                Expression first_emit;
                LocalTemporary first_emit_temp;

                protected virtual Expression ResolveArrayElement (EmitContext ec, Expression element)
                {
                        element = element.Resolve (ec);
                        if (element == null)
                                return null;

                        if (element is CompoundAssign.TargetExpression) {
                                if (first_emit != null)
                                        throw new InternalErrorException ("Can only handle one mutator at a time");
                                first_emit = element;
                                element = first_emit_temp = new LocalTemporary (element.Type);
                        }

                        return Convert.ImplicitConversionRequired (
                                ec, element, array_element_type, loc);
                }

                protected bool ResolveInitializers (EmitContext ec)
                {
                        if (initializers == null) {
                                return !expect_initializers;
                        }
                                                
                        //
                        // We use this to store all the date values in the order in which we
                        // will need to store them in the byte blob later
                        //
                        array_data = new ArrayList ();
                        bounds = new System.Collections.Specialized.HybridDictionary ();
                        
                        if (arguments != null)
                                return CheckIndices (ec, initializers, 0, true);

                        arguments = new ArrayList ();

                        if (!CheckIndices (ec, initializers, 0, false))
                                return false;
                                
                        UpdateIndices ();
                                
                        return true;
                }

                //
                // Resolved the type of the array
                //
                bool ResolveArrayType (EmitContext ec)
                {
                        if (requested_base_type == null) {
                                Report.Error (622, loc, "Can only use array initializer expressions to assign to array types. Try using a new expression instead");
                                return false;
                        }

                        if (requested_base_type is VarExpr) {
                                Report.Error (820, loc, "An implicitly typed local variable declarator cannot use an array initializer");
                                return false;
                        }
                        
                        StringBuilder array_qualifier = new StringBuilder (rank);

                        //
                        // `In the first form allocates an array instace of the type that results
                        // from deleting each of the individual expression from the expression list'
                        //
                        if (num_arguments > 0) {
                                array_qualifier.Append ("[");
                                for (int i = num_arguments-1; i > 0; i--)
                                        array_qualifier.Append (",");
                                array_qualifier.Append ("]");
                        }

                        //
                        // Lookup the type
                        //
                        TypeExpr array_type_expr;
                        array_type_expr = new ComposedCast (requested_base_type, array_qualifier.ToString (), loc);
                        array_type_expr = array_type_expr.ResolveAsTypeTerminal (ec, false);
                        if (array_type_expr == null)
                                return false;

                        type = array_type_expr.Type;
                        array_element_type = TypeManager.GetElementType (type);
                        dimensions = type.GetArrayRank ();

                        return true;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (type != null)
                                return this;

                        if (!ResolveArrayType (ec))
                                return null;

                        //
                        // First step is to validate the initializers and fill
                        // in any missing bits
                        //
                        if (!ResolveInitializers (ec))
                                return null;

                        if (arguments.Count != dimensions) {
                                Error_IncorrectArrayInitializer (loc);
                        }

                        foreach (Argument a in arguments){
                                if (!a.Resolve (ec, loc))
                                        continue;

                                a.Expr = ConvertExpressionToArrayIndex (ec, a.Expr);
                        }
                                                        
                        eclass = ExprClass.Value;
                        return this;
                }

                MethodInfo GetArrayMethod (int arguments)
                {
                        ModuleBuilder mb = RootContext.ToplevelTypes.Builder;

                        Type[] arg_types = new Type[arguments];
                        for (int i = 0; i < arguments; i++)
                                arg_types[i] = TypeManager.int32_type;

                        MethodInfo mi = mb.GetArrayMethod (type, ".ctor", CallingConventions.HasThis, null,
                                                        arg_types);

                        if (mi == null) {
                                Report.Error (-6, "New invocation: Can not find a constructor for " +
                                                  "this argument list");
                                return null;
                        }

                        return mi; 
                }

                byte [] MakeByteBlob ()
                {
                        int factor;
                        byte [] data;
                        byte [] element;
                        int count = array_data.Count;

                        if (TypeManager.IsEnumType (array_element_type))
                                array_element_type = TypeManager.GetEnumUnderlyingType (array_element_type);
                        
                        factor = GetTypeSize (array_element_type);
                        if (factor == 0)
                                throw new Exception ("unrecognized type in MakeByteBlob: " + array_element_type);

                        data = new byte [(count * factor + 3) & ~3];
                        int idx = 0;

                        for (int i = 0; i < count; ++i) {
                                object v = array_data [i];

                                if (v is EnumConstant)
                                        v = ((EnumConstant) v).Child;
                                
                                if (v is Constant && !(v is StringConstant))
                                        v = ((Constant) v).GetValue ();
                                else {
                                        idx += factor;
                                        continue;
                                }
                                
                                if (array_element_type == TypeManager.int64_type){
                                        if (!(v is Expression)){
                                                long val = (long) v;
                                                
                                                for (int j = 0; j < factor; ++j) {
                                                        data [idx + j] = (byte) (val & 0xFF);
                                                        val = (val >> 8);
                                                }
                                        }
                                } else if (array_element_type == TypeManager.uint64_type){
                                        if (!(v is Expression)){
                                                ulong val = (ulong) v;

                                                for (int j = 0; j < factor; ++j) {
                                                        data [idx + j] = (byte) (val & 0xFF);
                                                        val = (val >> 8);
                                                }
                                        }
                                } else if (array_element_type == TypeManager.float_type) {
                                        if (!(v is Expression)){
                                                element = BitConverter.GetBytes ((float) v);
                                                        
                                                for (int j = 0; j < factor; ++j)
                                                        data [idx + j] = element [j];
                                                if (!BitConverter.IsLittleEndian)
                                                        System.Array.Reverse (data, idx, 4);
                                        }
                                } else if (array_element_type == TypeManager.double_type) {
                                        if (!(v is Expression)){
                                                element = BitConverter.GetBytes ((double) v);

                                                for (int j = 0; j < factor; ++j)
                                                        data [idx + j] = element [j];

                                                // FIXME: Handle the ARM float format.
                                                if (!BitConverter.IsLittleEndian)
                                                        System.Array.Reverse (data, idx, 8);
                                        }
                                } else if (array_element_type == TypeManager.char_type){
                                        if (!(v is Expression)){
                                                int val = (int) ((char) v);
                                                
                                                data [idx] = (byte) (val & 0xff);
                                                data [idx+1] = (byte) (val >> 8);
                                        }
                                } else if (array_element_type == TypeManager.short_type){
                                        if (!(v is Expression)){
                                                int val = (int) ((short) v);
                                        
                                                data [idx] = (byte) (val & 0xff);
                                                data [idx+1] = (byte) (val >> 8);
                                        }
                                } else if (array_element_type == TypeManager.ushort_type){
                                        if (!(v is Expression)){
                                                int val = (int) ((ushort) v);
                                        
                                                data [idx] = (byte) (val & 0xff);
                                                data [idx+1] = (byte) (val >> 8);
                                        }
                                } else if (array_element_type == TypeManager.int32_type) {
                                        if (!(v is Expression)){
                                                int val = (int) v;
                                        
                                                data [idx]   = (byte) (val & 0xff);
                                                data [idx+1] = (byte) ((val >> 8) & 0xff);
                                                data [idx+2] = (byte) ((val >> 16) & 0xff);
                                                data [idx+3] = (byte) (val >> 24);
                                        }
                                } else if (array_element_type == TypeManager.uint32_type) {
                                        if (!(v is Expression)){
                                                uint val = (uint) v;
                                        
                                                data [idx]   = (byte) (val & 0xff);
                                                data [idx+1] = (byte) ((val >> 8) & 0xff);
                                                data [idx+2] = (byte) ((val >> 16) & 0xff);
                                                data [idx+3] = (byte) (val >> 24);
                                        }
                                } else if (array_element_type == TypeManager.sbyte_type) {
                                        if (!(v is Expression)){
                                                sbyte val = (sbyte) v;
                                                data [idx] = (byte) val;
                                        }
                                } else if (array_element_type == TypeManager.byte_type) {
                                        if (!(v is Expression)){
                                                byte val = (byte) v;
                                                data [idx] = (byte) val;
                                        }
                                } else if (array_element_type == TypeManager.bool_type) {
                                        if (!(v is Expression)){
                                                bool val = (bool) v;
                                                data [idx] = (byte) (val ? 1 : 0);
                                        }
                                } else if (array_element_type == TypeManager.decimal_type){
                                        if (!(v is Expression)){
                                                int [] bits = Decimal.GetBits ((decimal) v);
                                                int p = idx;

                                                // FIXME: For some reason, this doesn't work on the MS runtime.
                                                int [] nbits = new int [4];
                                                nbits [0] = bits [3];
                                                nbits [1] = bits [2];
                                                nbits [2] = bits [0];
                                                nbits [3] = bits [1];
                                                
                                                for (int j = 0; j < 4; j++){
                                                        data [p++] = (byte) (nbits [j] & 0xff);
                                                        data [p++] = (byte) ((nbits [j] >> 8) & 0xff);
                                                        data [p++] = (byte) ((nbits [j] >> 16) & 0xff);
                                                        data [p++] = (byte) (nbits [j] >> 24);
                                                }
                                        }
                                } else
                                        throw new Exception ("Unrecognized type in MakeByteBlob: " + array_element_type);

                                idx += factor;
                        }

                        return data;
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        array_element_type = storey.MutateType (array_element_type);
                        type = storey.MutateType (type);
                        if (arguments != null) {
                                foreach (Argument a in arguments)
                                        a.Expr.MutateHoistedGenericType (storey);
                        }
                        
                        if (array_data != null) {
                                foreach (Expression e in array_data) {
                                        // Don't mutate values optimized away
                                        if (e == null)
                                                continue;

                                        e.MutateHoistedGenericType (storey);
                                }
                        }
                }

                //
                // Emits the initializers for the array
                //
                void EmitStaticInitializers (EmitContext ec)
                {
                        // FIXME: This should go to Resolve !
                        if (TypeManager.void_initializearray_array_fieldhandle == null) {
                                TypeManager.void_initializearray_array_fieldhandle = TypeManager.GetPredefinedMethod (
                                        TypeManager.runtime_helpers_type, "InitializeArray", loc,
                                        TypeManager.array_type, TypeManager.runtime_field_handle_type);
                                if (TypeManager.void_initializearray_array_fieldhandle == null)
                                        return;
                        }

                        //
                        // First, the static data
                        //
                        FieldBuilder fb;
                        ILGenerator ig = ec.ig;
                        
                        byte [] data = MakeByteBlob ();

                        fb = RootContext.MakeStaticData (data);

                        ig.Emit (OpCodes.Dup);
                        ig.Emit (OpCodes.Ldtoken, fb);
                        ig.Emit (OpCodes.Call,
                                 TypeManager.void_initializearray_array_fieldhandle);
                }

                //
                // Emits pieces of the array that can not be computed at compile
                // time (variables and string locations).
                //
                // This always expect the top value on the stack to be the array
                //
                void EmitDynamicInitializers (EmitContext ec, bool emitConstants)
                {
                        ILGenerator ig = ec.ig;
                        int dims = bounds.Count;
                        int [] current_pos = new int [dims];

                        MethodInfo set = null;

                        if (dims != 1){
                                Type [] args = new Type [dims + 1];

                                for (int j = 0; j < dims; j++)
                                        args [j] = TypeManager.int32_type;
                                args [dims] = array_element_type;

                                set = RootContext.ToplevelTypes.Builder.GetArrayMethod (
                                        type, "Set",
                                        CallingConventions.HasThis | CallingConventions.Standard,
                                        TypeManager.void_type, args);
                        }

                        for (int i = 0; i < array_data.Count; i++){

                                Expression e = (Expression)array_data [i];

                                // Constant can be initialized via StaticInitializer
                                if (e != null && !(!emitConstants && e is Constant)) {
                                        Type etype = e.Type;

                                        ig.Emit (OpCodes.Dup);

                                        for (int idx = 0; idx < dims; idx++) 
                                                IntConstant.EmitInt (ig, current_pos [idx]);

                                        //
                                        // If we are dealing with a struct, get the
                                        // address of it, so we can store it.
                                        //
                                        if ((dims == 1) && TypeManager.IsStruct (etype) &&
                                            (!TypeManager.IsBuiltinOrEnum (etype) ||
                                             etype == TypeManager.decimal_type)) {

                                                ig.Emit (OpCodes.Ldelema, etype);
                                        }

                                        e.Emit (ec);

                                        if (dims == 1) {
                                                bool is_stobj, has_type_arg;
                                                OpCode op = ArrayAccess.GetStoreOpcode (etype, out is_stobj, out has_type_arg);
                                                if (is_stobj)
                                                        ig.Emit (OpCodes.Stobj, etype);
                                                else if (has_type_arg)
                                                        ig.Emit (op, etype);
                                                else
                                                        ig.Emit (op);
                                        } else 
                                                ig.Emit (OpCodes.Call, set);

                                }
                                
                                //
                                // Advance counter
                                //
                                for (int j = dims - 1; j >= 0; j--){
                                        current_pos [j]++;
                                        if (current_pos [j] < (int) bounds [j])
                                                break;
                                        current_pos [j] = 0;
                                }
                        }
                }

                public override void Emit (EmitContext ec)
                {
                        ILGenerator ig = ec.ig;

                        if (first_emit != null) {
                                first_emit.Emit (ec);
                                first_emit_temp.Store (ec);
                        }

                        foreach (Argument a in arguments)
                                a.Emit (ec);

                        if (arguments.Count == 1)
                                ig.Emit (OpCodes.Newarr, array_element_type);
                        else {
                                ig.Emit (OpCodes.Newobj, GetArrayMethod (arguments.Count));
                        }
                        
                        if (initializers == null)
                                return;

                        // Emit static initializer for arrays which have contain more than 4 items and
                        // the static initializer will initialize at least 25% of array values.
                        // NOTE: const_initializers_count does not contain default constant values.
                        if (const_initializers_count >= 4 && const_initializers_count * 4 > (array_data.Count) &&
                                TypeManager.IsPrimitiveType (array_element_type)) {
                                EmitStaticInitializers (ec);

                                if (!only_constant_initializers)
                                        EmitDynamicInitializers (ec, false);
                        } else {
                                EmitDynamicInitializers (ec, true);
                        }

                        if (first_emit_temp != null)
                                first_emit_temp.Release (ec);
                }

                public override bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
                {
                        if (arguments.Count != 1) {
                                // Report.Error (-211, Location, "attribute can not encode multi-dimensional arrays");
                                return base.GetAttributableValue (ec, null, out value);
                        }

                        if (array_data == null) {
                                Constant c = (Constant)((Argument)arguments [0]).Expr;
                                if (c.IsDefaultValue) {
                                        value = Array.CreateInstance (array_element_type, 0);
                                        return true;
                                }
                                // Report.Error (-212, Location, "array should be initialized when passing it to an attribute");
                                return base.GetAttributableValue (ec, null, out value);
                        }
                        
                        Array ret = Array.CreateInstance (array_element_type, array_data.Count);
                        object element_value;
                        for (int i = 0; i < ret.Length; ++i)
                        {
                                Expression e = (Expression)array_data [i];

                                // Is null when an initializer is optimized (value == predefined value)
                                if (e == null) 
                                        continue;

                                if (!e.GetAttributableValue (ec, array_element_type, out element_value)) {
                                        value = null;
                                        return false;
                                }
                                ret.SetValue (element_value, i);
                        }
                        value = ret;
                        return true;
                }
                
                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        ArrayCreation target = (ArrayCreation) t;

                        if (requested_base_type != null)
                                target.requested_base_type = (FullNamedExpression)requested_base_type.Clone (clonectx);

                        if (arguments != null){
                                target.arguments = new ArrayList (arguments.Count);
                                foreach (Argument a in arguments)
                                        target.arguments.Add (a.Clone (clonectx));
                        }

                        if (initializers != null){
                                target.initializers = new ArrayList (initializers.Count);
                                foreach (object initializer in initializers)
                                        if (initializer is ArrayList) {
                                                ArrayList this_al = (ArrayList)initializer;
                                                ArrayList al = new ArrayList (this_al.Count);
                                                target.initializers.Add (al);
                                                foreach (Expression e in this_al)
                                                        al.Add (e.Clone (clonectx));
                                        } else {
                                                target.initializers.Add (((Expression)initializer).Clone (clonectx));
                                        }
                        }
                }
        }
        
        //
        // Represents an implicitly typed array epxression
        //
        public class ImplicitlyTypedArrayCreation : ArrayCreation
        {
                public ImplicitlyTypedArrayCreation (string rank, ArrayList initializers, Location loc)
                        : base (null, rank, initializers, loc)
                {
                        if (RootContext.Version <= LanguageVersion.ISO_2)
                                Report.FeatureIsNotAvailable (loc, "implicitly typed arrays");
                                
                        if (rank.Length > 2) {
                                while (rank [++dimensions] == ',');
                        } else {
                                dimensions = 1;
                        }
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (type != null)
                                return this;

                        if (!ResolveInitializers (ec))
                                return null;

                        if (array_element_type == null || array_element_type == TypeManager.null_type ||
                                array_element_type == TypeManager.void_type || array_element_type == TypeManager.anonymous_method_type ||
                                arguments.Count != dimensions) {
                                Error_NoBestType ();
                                return null;
                        }

                        //
                        // At this point we found common base type for all initializer elements
                        // but we have to be sure that all static initializer elements are of
                        // same type
                        //
                        UnifyInitializerElement (ec);

                        type = TypeManager.GetConstructedType (array_element_type, rank);
                        eclass = ExprClass.Value;
                        return this;
                }

                void Error_NoBestType ()
                {
                        Report.Error (826, loc,
                                "The type of an implicitly typed array cannot be inferred from the initializer. Try specifying array type explicitly");
                }

                //
                // Converts static initializer only
                //
                void UnifyInitializerElement (EmitContext ec)
                {
                        for (int i = 0; i < array_data.Count; ++i) {
                                Expression e = (Expression)array_data[i];
                                if (e != null)
                                        array_data [i] = Convert.ImplicitConversion (ec, e, array_element_type, Location.Null);
                        }
                }

                protected override Expression ResolveArrayElement (EmitContext ec, Expression element)
                {
                        element = element.Resolve (ec);
                        if (element == null)
                                return null;
                        
                        if (array_element_type == null) {
                                if (element.Type != TypeManager.null_type)
                                        array_element_type = element.Type;

                                return element;
                        }

                        if (Convert.ImplicitConversionExists (ec, element, array_element_type)) {
                                return element;
                        }

                        if (Convert.ImplicitConversionExists (ec, new TypeExpression (array_element_type, loc), element.Type)) {
                                array_element_type = element.Type;
                                return element;
                        }

                        Error_NoBestType ();
                        return null;
                }
        }       
        
        public sealed class CompilerGeneratedThis : This
        {
                public static This Instance = new CompilerGeneratedThis ();

                private CompilerGeneratedThis ()
                        : base (Location.Null)
                {
                }

                public CompilerGeneratedThis (Type type, Location loc)
                        : base (loc)
                {
                        this.type = type;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        eclass = ExprClass.Variable;
                        if (type == null)
                                type = ec.ContainerType;
                        return this;
                }

                public override HoistedVariable GetHoistedVariable (EmitContext ec)
                {
                        return null;
                }
        }
        
        /// <summary>
        ///   Represents the `this' construct
        /// </summary>

        public class This : VariableReference
        {
                sealed class ThisVariable : ILocalVariable
                {
                        public static readonly ILocalVariable Instance = new ThisVariable ();

                        public void Emit (EmitContext ec)
                        {
                                ec.ig.Emit (OpCodes.Ldarg_0);
                        }

                        public void EmitAssign (EmitContext ec)
                        {
                                throw new InvalidOperationException ();
                        }

                        public void EmitAddressOf (EmitContext ec)
                        {
                                ec.ig.Emit (OpCodes.Ldarg_0);
                        }
                }

                Block block;
                VariableInfo variable_info;
                bool is_struct;

                public This (Block block, Location loc)
                {
                        this.loc = loc;
                        this.block = block;
                }

                public This (Location loc)
                {
                        this.loc = loc;
                }

                public override VariableInfo VariableInfo {
                        get { return variable_info; }
                }

                public override bool IsFixed {
                        get { return false; }
                }

                public override HoistedVariable GetHoistedVariable (EmitContext ec)
                {
                        // Is null when probing IsHoisted
                        if (ec == null)
                                return null;

                        if (ec.CurrentAnonymousMethod == null)
                                return null;

                        AnonymousMethodStorey storey = ec.CurrentAnonymousMethod.Storey;
                        while (storey != null) {
                                AnonymousMethodStorey temp = storey.Parent as AnonymousMethodStorey;
                                if (temp == null)
                                        return storey.HoistedThis;

                                storey = temp;
                        }

                        return null;
                }

                public override bool IsRef {
                        get { return is_struct; }
                }

                protected override ILocalVariable Variable {
                        get { return ThisVariable.Instance; }
                }

                public static bool IsThisAvailable (EmitContext ec)
                {
                        if (ec.IsStatic || ec.IsInFieldInitializer)
                                return false;

                        if (ec.CurrentAnonymousMethod == null)
                                return true;

                        if (ec.TypeContainer is Struct && ec.CurrentIterator == null)
                                return false;

                        return true;
                }

                public bool ResolveBase (EmitContext ec)
                {
                        if (eclass != ExprClass.Invalid)
                                return true;

                        eclass = ExprClass.Variable;

                        if (ec.TypeContainer.CurrentType != null)
                                type = ec.TypeContainer.CurrentType;
                        else
                                type = ec.ContainerType;

                        if (!IsThisAvailable (ec)) {
                                if (ec.IsStatic) {
                                        Error (26, "Keyword `this' is not valid in a static property, static method, or static field initializer");
                                } else {
                                        Report.Error (1673, loc,
                                                "Anonymous methods inside structs cannot access instance members of `this'. " +
                                                "Consider copying `this' to a local variable outside the anonymous method and using the local instead");
                                }
                        }

                        is_struct = ec.TypeContainer is Struct;

                        if (block != null) {
                                if (block.Toplevel.ThisVariable != null)
                                        variable_info = block.Toplevel.ThisVariable.VariableInfo;

                                AnonymousExpression am = ec.CurrentAnonymousMethod;
                                if (am != null && ec.IsVariableCapturingRequired) {
                                        am.SetHasThisAccess ();
                                }
                        }
                        
                        return true;
                }

                //
                // Called from Invocation to check if the invocation is correct
                //
                public override void CheckMarshalByRefAccess (EmitContext ec)
                {
                        if ((variable_info != null) && !(TypeManager.IsStruct (type) && ec.OmitStructFlowAnalysis) &&
                            !variable_info.IsAssigned (ec)) {
                                Error (188, "The `this' object cannot be used before all of its " +
                                       "fields are assigned to");
                                variable_info.SetAssigned (ec);
                        }
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (1);
                        args.Add (new Argument (this));
                        
                        // Use typeless constant for ldarg.0 to save some
                        // space and avoid problems with anonymous stories
                        return CreateExpressionFactoryCall ("Constant", args);
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        if (!ResolveBase (ec))
                                return null;


                        if (ec.IsInFieldInitializer) {
                                Error (27, "Keyword `this' is not available in the current context");
                                return null;
                        }
                        
                        return this;
                }

                override public Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        if (!ResolveBase (ec))
                                return null;

                        if (variable_info != null)
                                variable_info.SetAssigned (ec);

                        if (ec.TypeContainer is Class){
                                if (right_side == EmptyExpression.UnaryAddress)
                                        Report.Error (459, loc, "Cannot take the address of `this' because it is read-only");
                                else if (right_side == EmptyExpression.OutAccess)
                                        Report.Error (1605, loc, "Cannot pass `this' as a ref or out argument because it is read-only");
                                else
                                        Report.Error (1604, loc, "Cannot assign to `this' because it is read-only");
                        }

                        return this;
                }

                public override int GetHashCode()
                {
                        return block.GetHashCode ();
                }

                public override string Name {
                        get { return "this"; }
                }

                public override bool Equals (object obj)
                {
                        This t = obj as This;
                        if (t == null)
                                return false;

                        return block == t.block;
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        This target = (This) t;

                        target.block = clonectx.LookupBlock (block);
                }

                public override void SetHasAddressTaken ()
                {
                        // Nothing
                }
        }

        /// <summary>
        ///   Represents the `__arglist' construct
        /// </summary>
        public class ArglistAccess : Expression
        {
                public ArglistAccess (Location loc)
                {
                        this.loc = loc;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        eclass = ExprClass.Variable;
                        type = typeof (ArglistAccess);

                        if (ec.IsInFieldInitializer || !ec.CurrentBlock.Toplevel.Parameters.HasArglist) 
                        {
                                Error (190, "The __arglist construct is valid only within " +
                                       "a variable argument method");
                                return this;
                        }

                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        ec.ig.Emit (OpCodes.Arglist);
                }

                protected override void CloneTo (CloneContext clonectx, Expression target)
                {
                        // nothing.
                }
        }

        /// <summary>
        ///   Represents the `__arglist (....)' construct
        /// </summary>
        public class Arglist : Expression
        {
                Argument[] Arguments;

                public Arglist (Location loc)
                        : this (Argument.Empty, loc)
                {
                }

                public Arglist (Argument[] args, Location l)
                {
                        Arguments = args;
                        loc = l;
                }

                public Type[] ArgumentTypes {
                        get {
                                Type[] retval = new Type [Arguments.Length];
                                for (int i = 0; i < Arguments.Length; i++)
                                        retval [i] = Arguments [i].Type;
                                return retval;
                        }
                }
                
                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        Report.Error (1952, loc, "An expression tree cannot contain a method with variable arguments");
                        return null;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        eclass = ExprClass.Variable;
                        type = typeof (ArglistAccess);

                        foreach (Argument arg in Arguments) {
                                if (!arg.Resolve (ec, loc))
                                        return null;
                        }

                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        foreach (Argument arg in Arguments)
                                arg.Emit (ec);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        foreach (Argument arg in Arguments)
                                arg.Expr.MutateHoistedGenericType (storey);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        Arglist target = (Arglist) t;

                        target.Arguments = new Argument [Arguments.Length];
                        for (int i = 0; i < Arguments.Length; i++)
                                target.Arguments [i] = Arguments [i].Clone (clonectx);
                }
        }

        /// <summary>
        ///   Implements the typeof operator
        /// </summary>
        public class TypeOf : Expression {
                Expression QueriedType;
                protected Type typearg;
                
                public TypeOf (Expression queried_type, Location l)
                {
                        QueriedType = queried_type;
                        loc = l;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (this));
                        args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
                        return CreateExpressionFactoryCall ("Constant", args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (eclass != ExprClass.Invalid)
                                return this;

                        TypeExpr texpr = QueriedType.ResolveAsTypeTerminal (ec, false);
                        if (texpr == null)
                                return null;

                        typearg = texpr.Type;

                        if (typearg == TypeManager.void_type) {
                                Error (673, "System.Void cannot be used from C#. Use typeof (void) to get the void type object");
                                return null;
                        }

                        if (typearg.IsPointer && !ec.InUnsafe){
                                UnsafeError (loc);
                                return null;
                        }

                        type = TypeManager.type_type;

                        return DoResolveBase ();
                }

                protected Expression DoResolveBase ()
                {
                        if (TypeManager.system_type_get_type_from_handle == null) {
                                TypeManager.system_type_get_type_from_handle = TypeManager.GetPredefinedMethod (
                                        TypeManager.type_type, "GetTypeFromHandle", loc, TypeManager.runtime_handle_type);
                        }

                        // Even though what is returned is a type object, it's treated as a value by the compiler.
                        // In particular, 'typeof (Foo).X' is something totally different from 'Foo.X'.
                        eclass = ExprClass.Value;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        ec.ig.Emit (OpCodes.Ldtoken, typearg);
                        ec.ig.Emit (OpCodes.Call, TypeManager.system_type_get_type_from_handle);
                }

                public override bool GetAttributableValue (EmitContext ec, Type value_type, out object value)
                {
                        if (TypeManager.ContainsGenericParameters (typearg) &&
                                !TypeManager.IsGenericTypeDefinition (typearg)) {
                                Report.SymbolRelatedToPreviousError (typearg);
                                Report.Error (416, loc, "`{0}': an attribute argument cannot use type parameters",
                                             TypeManager.CSharpName (typearg));
                                value = null;
                                return false;
                        }

                        if (value_type == TypeManager.object_type) {
                                value = (object)typearg;
                                return true;
                        }
                        value = typearg;
                        return true;
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        typearg = storey.MutateType (typearg);
                }

                public Type TypeArgument {
                        get {
                                return typearg;
                        }
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        TypeOf target = (TypeOf) t;
                        if (QueriedType != null)
                                target.QueriedType = QueriedType.Clone (clonectx);
                }
        }

        /// <summary>
        ///   Implements the `typeof (void)' operator
        /// </summary>
        public class TypeOfVoid : TypeOf {
                public TypeOfVoid (Location l) : base (null, l)
                {
                        loc = l;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        type = TypeManager.type_type;
                        typearg = TypeManager.void_type;

                        return DoResolveBase ();
                }
        }

        class TypeOfMethodInfo : TypeOfMethod
        {
                public TypeOfMethodInfo (MethodBase method, Location loc)
                        : base (method, loc)
                {
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        type = typeof (MethodInfo);
                        return base.DoResolve (ec);
                }

                public override void Emit (EmitContext ec)
                {
                        ec.ig.Emit (OpCodes.Ldtoken, (MethodInfo) method);
                        base.Emit (ec);
                        ec.ig.Emit (OpCodes.Castclass, type);
                }
        }

        class TypeOfConstructorInfo : TypeOfMethod
        {
                public TypeOfConstructorInfo (MethodBase method, Location loc)
                        : base (method, loc)
                {
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        type = typeof (ConstructorInfo);
                        return base.DoResolve (ec);
                }

                public override void Emit (EmitContext ec)
                {
                        ec.ig.Emit (OpCodes.Ldtoken, (ConstructorInfo) method);
                        base.Emit (ec);
                        ec.ig.Emit (OpCodes.Castclass, type);
                }
        }

        abstract class TypeOfMethod : Expression
        {
                protected readonly MethodBase method;

                protected TypeOfMethod (MethodBase method, Location loc)
                {
                        this.method = method;
                        this.loc = loc;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (this));
                        args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
                        return CreateExpressionFactoryCall ("Constant", args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        bool is_generic = TypeManager.IsGenericType (method.DeclaringType);
                        MethodInfo mi = is_generic ?
                                TypeManager.methodbase_get_type_from_handle_generic :
                                TypeManager.methodbase_get_type_from_handle;

                        if (mi == null) {
                                Type t = TypeManager.CoreLookupType ("System.Reflection", "MethodBase", Kind.Class, true);
                                Type handle_type = TypeManager.CoreLookupType ("System", "RuntimeMethodHandle", Kind.Class, true);

                                if (t == null || handle_type == null)
                                        return null;

                                mi = TypeManager.GetPredefinedMethod (t, "GetMethodFromHandle", loc,
                                        is_generic ?
                                        new Type[] { handle_type, TypeManager.runtime_handle_type } :
                                        new Type[] { handle_type } );

                                if (is_generic)
                                        TypeManager.methodbase_get_type_from_handle_generic = mi;
                                else
                                        TypeManager.methodbase_get_type_from_handle = mi;
                        }

                        eclass = ExprClass.Value;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        bool is_generic = TypeManager.IsGenericType (method.DeclaringType);
                        MethodInfo mi;
                        if (is_generic) {
                                mi = TypeManager.methodbase_get_type_from_handle_generic;
                                ec.ig.Emit (OpCodes.Ldtoken, method.DeclaringType);
                        } else {
                                mi = TypeManager.methodbase_get_type_from_handle;
                        }

                        ec.ig.Emit (OpCodes.Call, mi);
                }
        }

        internal class TypeOfField : Expression
        {
                readonly FieldInfo field;

                public TypeOfField (FieldInfo field, Location loc)
                {
                        this.field = field;
                        this.loc = loc;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (TypeManager.fieldinfo_get_field_from_handle == null) {
                                Type t = TypeManager.CoreLookupType ("System.Reflection", "FieldInfo", Kind.Class, true);
                                Type handle_type = TypeManager.CoreLookupType ("System", "RuntimeFieldHandle", Kind.Class, true);

                                if (t != null && handle_type != null)
                                        TypeManager.fieldinfo_get_field_from_handle = TypeManager.GetPredefinedMethod (t,
                                                "GetFieldFromHandle", loc, handle_type);
                        }

                        type = typeof (FieldInfo);
                        eclass = ExprClass.Value;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        ec.ig.Emit (OpCodes.Ldtoken, field);
                        ec.ig.Emit (OpCodes.Call, TypeManager.fieldinfo_get_field_from_handle);
                }
        }

        /// <summary>
        ///   Implements the sizeof expression
        /// </summary>
        public class SizeOf : Expression {
                readonly Expression QueriedType;
                Type type_queried;
                
                public SizeOf (Expression queried_type, Location l)
                {
                        this.QueriedType = queried_type;
                        loc = l;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        Error_PointerInsideExpressionTree ();
                        return null;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        TypeExpr texpr = QueriedType.ResolveAsTypeTerminal (ec, false);
                        if (texpr == null)
                                return null;

                        type_queried = texpr.Type;
                        if (TypeManager.IsEnumType (type_queried))
                                type_queried = TypeManager.GetEnumUnderlyingType (type_queried);

                        int size_of = GetTypeSize (type_queried);
                        if (size_of > 0) {
                                return new IntConstant (size_of, loc);
                        }

                        if (!TypeManager.VerifyUnManaged (type_queried, loc)){
                                return null;
                        }

                        if (!ec.InUnsafe) {
                                Report.Error (233, loc,
                                        "`{0}' does not have a predefined size, therefore sizeof can only be used in an unsafe context (consider using System.Runtime.InteropServices.Marshal.SizeOf)",
                                        TypeManager.CSharpName (type_queried));
                        }
                        
                        type = TypeManager.int32_type;
                        eclass = ExprClass.Value;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        int size = GetTypeSize (type_queried);

                        if (size == 0)
                                ec.ig.Emit (OpCodes.Sizeof, type_queried);
                        else
                                IntConstant.EmitInt (ec.ig, size);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                }
        }

        /// <summary>
        ///   Implements the qualified-alias-member (::) expression.
        /// </summary>
        public class QualifiedAliasMember : MemberAccess
        {
                readonly string alias;
                public static readonly string GlobalAlias = "global";

                public QualifiedAliasMember (string alias, string identifier, TypeArguments targs, Location l)
                        : base (null, identifier, targs, l)
                {
                        this.alias = alias;
                }

                public QualifiedAliasMember (string alias, string identifier, Location l)
                        : base (null, identifier, l)
                {
                        this.alias = alias;
                }

                public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
                {
                        if (alias == GlobalAlias) {
                                expr = GlobalRootNamespace.Instance;
                                return base.ResolveAsTypeStep (ec, silent);
                        }

                        int errors = Report.Errors;
                        expr = ec.DeclContainer.NamespaceEntry.LookupAlias (alias);
                        if (expr == null) {
                                if (errors == Report.Errors)
                                        Report.Error (432, loc, "Alias `{0}' not found", alias);
                                return null;
                        }

                        FullNamedExpression fne = base.ResolveAsTypeStep (ec, silent);
                        if (fne == null)
                                return null;

                        if (expr.eclass == ExprClass.Type) {
                                if (!silent) {
                                        Report.Error (431, loc,
                                                "Alias `{0}' cannot be used with '::' since it denotes a type. Consider replacing '::' with '.'", alias);
                                }
                                return null;
                        }

                        return fne;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        return ResolveAsTypeStep (ec, false);
                }

                protected override void Error_IdentifierNotFound (IResolveContext rc, FullNamedExpression expr_type, string identifier)
                {
                        Report.Error (687, loc,
                                "A namespace alias qualifier `{0}' did not resolve to a namespace or a type",
                                GetSignatureForError ());
                }

                public override string GetSignatureForError ()
                {
                        string name = Name;
                        if (targs != null) {
                                name = TypeManager.RemoveGenericArity (Name) + "<" +
                                        targs.GetSignatureForError () + ">";
                        }

                        return alias + "::" + name;
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        // Nothing 
                }
        }

        /// <summary>
        ///   Implements the member access expression
        /// </summary>
        public class MemberAccess : ATypeNameExpression {
                protected Expression expr;

                public MemberAccess (Expression expr, string id)
                        : base (id, expr.Location)
                {
                        this.expr = expr;
                }

                public MemberAccess (Expression expr, string identifier, Location loc)
                        : base (identifier, loc)
                {
                        this.expr = expr;
                }

                public MemberAccess (Expression expr, string identifier, TypeArguments args, Location loc)
                        : base (identifier, args, loc)
                {
                        this.expr = expr;
                }

                Expression DoResolve (EmitContext ec, Expression right_side)
                {
                        if (type != null)
                                throw new Exception ();

                        //
                        // Resolve the expression with flow analysis turned off, we'll do the definite
                        // assignment checks later.  This is because we don't know yet what the expression
                        // will resolve to - it may resolve to a FieldExpr and in this case we must do the
                        // definite assignment check on the actual field and not on the whole struct.
                        //

                        SimpleName original = expr as SimpleName;
                        Expression expr_resolved = expr.Resolve (ec,
                                ResolveFlags.VariableOrValue | ResolveFlags.Type |
                                ResolveFlags.Intermediate | ResolveFlags.DisableStructFlowAnalysis);

                        if (expr_resolved == null)
                                return null;

                        string LookupIdentifier = MemberName.MakeName (Name, targs);

                        Namespace ns = expr_resolved as Namespace;
                        if (ns != null) {
                                FullNamedExpression retval = ns.Lookup (ec.DeclContainer, LookupIdentifier, loc);

                                if (retval == null)
                                        ns.Error_NamespaceDoesNotExist (ec.DeclContainer, loc, LookupIdentifier);
                                else if (targs != null)
                                        retval = new GenericTypeExpr (retval.Type, targs, loc).ResolveAsTypeStep (ec, false);

                                return retval;
                        }

                        Type expr_type = expr_resolved.Type;
                        if (expr_type.IsPointer || expr_type == TypeManager.void_type ||
                                expr_type == TypeManager.null_type || expr_type == TypeManager.anonymous_method_type) {
                                Unary.Error_OperatorCannotBeApplied (loc, ".", expr_type);
                                return null;
                        }

                        Constant c = expr_resolved as Constant;
                        if (c != null && c.GetValue () == null) {
                                Report.Warning (1720, 1, loc, "Expression will always cause a `{0}'",
                                        "System.NullReferenceException");
                        }

                        if (targs != null) {
                                if (!targs.Resolve (ec))
                                        return null;
                        }

                        Expression member_lookup;
                        member_lookup = MemberLookup (
                                ec.ContainerType, expr_type, expr_type, Name, loc);

                        if (member_lookup == null && targs != null) {
                                member_lookup = MemberLookup (
                                        ec.ContainerType, expr_type, expr_type, LookupIdentifier, loc);
                        }

                        if (member_lookup == null) {
                                ExprClass expr_eclass = expr_resolved.eclass;

                                //
                                // Extension methods are not allowed on all expression types
                                //
                                if (expr_eclass == ExprClass.Value || expr_eclass == ExprClass.Variable ||
                                        expr_eclass == ExprClass.IndexerAccess || expr_eclass == ExprClass.PropertyAccess ||
                                        expr_eclass == ExprClass.EventAccess) {
                                        ExtensionMethodGroupExpr ex_method_lookup = ec.TypeContainer.LookupExtensionMethod (expr_type, Name, loc);
                                        if (ex_method_lookup != null) {
                                                ex_method_lookup.ExtensionExpression = expr_resolved;

                                                if (targs != null) {
                                                        ex_method_lookup.SetTypeArguments (targs);
                                                }

                                                return ex_method_lookup.DoResolve (ec);
                                        }
                                }

                                expr = expr_resolved;
                                member_lookup = Error_MemberLookupFailed (
                                        ec.ContainerType, expr_type, expr_type, Name, null,
                                        AllMemberTypes, AllBindingFlags);
                                if (member_lookup == null)
                                        return null;
                        }

                        TypeExpr texpr = member_lookup as TypeExpr;
                        if (texpr != null) {
                                if (!(expr_resolved is TypeExpr) && 
                                    (original == null || !original.IdenticalNameAndTypeName (ec, expr_resolved, loc))) {
                                        Report.Error (572, loc, "`{0}': cannot reference a type through an expression; try `{1}' instead",
                                                Name, member_lookup.GetSignatureForError ());
                                        return null;
                                }

                                if (!texpr.CheckAccessLevel (ec.DeclContainer)) {
                                        Report.SymbolRelatedToPreviousError (member_lookup.Type);
                                        ErrorIsInaccesible (loc, TypeManager.CSharpName (member_lookup.Type));
                                        return null;
                                }

                                GenericTypeExpr ct = expr_resolved as GenericTypeExpr;
                                if (ct != null) {
                                        //
                                        // When looking up a nested type in a generic instance
                                        // via reflection, we always get a generic type definition
                                        // and not a generic instance - so we have to do this here.
                                        //
                                        // See gtest-172-lib.cs and gtest-172.cs for an example.
                                        //
                                        ct = new GenericTypeExpr (
                                                member_lookup.Type, ct.TypeArguments, loc);

                                        return ct.ResolveAsTypeStep (ec, false);
                                }

                                return member_lookup;
                        }

                        MemberExpr me = (MemberExpr) member_lookup;
                        me = me.ResolveMemberAccess (ec, expr_resolved, loc, original);
                        if (me == null)
                                return null;

                        if (targs != null) {
                                me.SetTypeArguments (targs);
                        }

                        if (original != null && !TypeManager.IsValueType (expr_type)) {
                                if (me.IsInstance) {
                                        LocalVariableReference var = expr_resolved as LocalVariableReference;
                                        if (var != null && !var.VerifyAssigned (ec))
                                                return null;
                                }
                        }

                        // The following DoResolve/DoResolveLValue will do the definite assignment
                        // check.

                        if (right_side != null)
                                return me.DoResolveLValue (ec, right_side);
                        else
                                return me.DoResolve (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        return DoResolve (ec, null);
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        return DoResolve (ec, right_side);
                }

                public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
                {
                        return ResolveNamespaceOrType (ec, silent);
                }

                public FullNamedExpression ResolveNamespaceOrType (IResolveContext rc, bool silent)
                {
                        FullNamedExpression expr_resolved = expr.ResolveAsTypeStep (rc, silent);

                        if (expr_resolved == null)
                                return null;

                        string LookupIdentifier = MemberName.MakeName (Name, targs);

                        Namespace ns = expr_resolved as Namespace;
                        if (ns != null) {
                                FullNamedExpression retval = ns.Lookup (rc.DeclContainer, LookupIdentifier, loc);

                                if (retval == null && !silent)
                                        ns.Error_NamespaceDoesNotExist (rc.DeclContainer, loc, LookupIdentifier);
                                else if (targs != null)
                                        retval = new GenericTypeExpr (retval.Type, targs, loc).ResolveAsTypeStep (rc, silent);

                                return retval;
                        }

                        TypeExpr tnew_expr = expr_resolved.ResolveAsTypeTerminal (rc, false);
                        if (tnew_expr == null)
                                return null;

                        if (tnew_expr is TypeParameterExpr) {
                                Report.Error (704, loc, "A nested type cannot be specified through a type parameter `{0}'",
                                        tnew_expr.GetSignatureForError ());
                                return null;
                        }

                        Type expr_type = tnew_expr.Type;
                        Expression member_lookup = MemberLookup (
                                rc.DeclContainer.TypeBuilder, expr_type, expr_type, LookupIdentifier,
                                MemberTypes.NestedType, BindingFlags.Public | BindingFlags.NonPublic, loc);
                        if (member_lookup == null) {
                                if (silent)
                                        return null;

                                Error_IdentifierNotFound (rc, expr_resolved, LookupIdentifier);
                                return null;
                        }

                        TypeExpr texpr = member_lookup.ResolveAsTypeTerminal (rc, false);
                        if (texpr == null)
                                return null;

                        TypeArguments the_args = targs;
                        Type declaring_type = texpr.Type.DeclaringType;
                        if (TypeManager.HasGenericArguments (declaring_type) && !TypeManager.IsGenericTypeDefinition (expr_type)) {
                                while (!TypeManager.IsEqual (TypeManager.DropGenericTypeArguments (expr_type), declaring_type)) {
                                        expr_type = expr_type.BaseType;
                                }
                                
                                TypeArguments new_args = new TypeArguments ();
                                foreach (Type decl in TypeManager.GetTypeArguments (expr_type))
                                        new_args.Add (new TypeExpression (decl, loc));

                                if (targs != null)
                                        new_args.Add (targs);

                                the_args = new_args;
                        }

                        if (the_args != null) {
                                GenericTypeExpr ctype = new GenericTypeExpr (texpr.Type, the_args, loc);
                                return ctype.ResolveAsTypeStep (rc, false);
                        }

                        return texpr;
                }

                protected virtual void Error_IdentifierNotFound (IResolveContext rc, FullNamedExpression expr_type, string identifier)
                {
                        Expression member_lookup = MemberLookup (
                                rc.DeclContainer.TypeBuilder, expr_type.Type, expr_type.Type, SimpleName.RemoveGenericArity (identifier),
                                MemberTypes.NestedType, BindingFlags.Public | BindingFlags.NonPublic, loc);

                        if (member_lookup != null) {
                                expr_type = member_lookup.ResolveAsTypeTerminal (rc, false);
                                if (expr_type == null)
                                        return;

                                Namespace.Error_TypeArgumentsCannotBeUsed (expr_type, loc);
                                return;
                        }

                        member_lookup = MemberLookup (
                                rc.DeclContainer.TypeBuilder, expr_type.Type, expr_type.Type, identifier,
                                        MemberTypes.All, BindingFlags.Public | BindingFlags.NonPublic, loc);

                        if (member_lookup == null) {
                                Report.Error (426, loc, "The nested type `{0}' does not exist in the type `{1}'",
                                                  Name, expr_type.GetSignatureForError ());
                        } else {
                                // TODO: Report.SymbolRelatedToPreviousError
                                member_lookup.Error_UnexpectedKind (null, "type", loc);
                        }
                }

                protected override void Error_TypeDoesNotContainDefinition (Type type, string name)
                {
                        if (RootContext.Version > LanguageVersion.ISO_2 &&
                                ((expr.eclass & (ExprClass.Value | ExprClass.Variable)) != 0)) {
                                Report.Error (1061, loc, "Type `{0}' does not contain a definition for `{1}' and no " +
                                        "extension method `{1}' of type `{0}' could be found " +
                                        "(are you missing a using directive or an assembly reference?)",
                                        TypeManager.CSharpName (type), name);
                                return;
                        }

                        base.Error_TypeDoesNotContainDefinition (type, name);
                }

                public override string GetSignatureForError ()
                {
                        return expr.GetSignatureForError () + "." + base.GetSignatureForError ();
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        MemberAccess target = (MemberAccess) t;

                        target.expr = expr.Clone (clonectx);
                }
        }

        /// <summary>
        ///   Implements checked expressions
        /// </summary>
        public class CheckedExpr : Expression {

                public Expression Expr;

                public CheckedExpr (Expression e, Location l)
                {
                        Expr = e;
                        loc = l;
                }
                
                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, true))
                                return Expr.CreateExpressionTree (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, true))
                                Expr = Expr.Resolve (ec);
                        
                        if (Expr == null)
                                return null;

                        if (Expr is Constant || Expr is MethodGroupExpr || Expr is AnonymousMethodExpression)
                                return Expr;
                        
                        eclass = Expr.eclass;
                        type = Expr.Type;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, true))
                                Expr.Emit (ec);
                }

                public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, true))
                                Expr.EmitBranchable (ec, target, on_true);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        Expr.MutateHoistedGenericType (storey);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        CheckedExpr target = (CheckedExpr) t;

                        target.Expr = Expr.Clone (clonectx);
                }
        }

        /// <summary>
        ///   Implements the unchecked expression
        /// </summary>
        public class UnCheckedExpr : Expression {

                public Expression Expr;

                public UnCheckedExpr (Expression e, Location l)
                {
                        Expr = e;
                        loc = l;
                }
                
                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, false))
                                return Expr.CreateExpressionTree (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, false))
                                Expr = Expr.Resolve (ec);

                        if (Expr == null)
                                return null;

                        if (Expr is Constant || Expr is MethodGroupExpr || Expr is AnonymousMethodExpression)
                                return Expr;
                        
                        eclass = Expr.eclass;
                        type = Expr.Type;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, false))
                                Expr.Emit (ec);
                }
                
                public override void EmitBranchable (EmitContext ec, Label target, bool on_true)
                {
                        using (ec.With (EmitContext.Flags.AllCheckStateFlags, false))
                                Expr.EmitBranchable (ec, target, on_true);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        Expr.MutateHoistedGenericType (storey);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        UnCheckedExpr target = (UnCheckedExpr) t;

                        target.Expr = Expr.Clone (clonectx);
                }
        }

        /// <summary>
        ///   An Element Access expression.
        ///
        ///   During semantic analysis these are transformed into 
        ///   IndexerAccess, ArrayAccess or a PointerArithmetic.
        /// </summary>
        public class ElementAccess : Expression {
                public ArrayList  Arguments;
                public Expression Expr;
                
                public ElementAccess (Expression e, ArrayList e_list)
                {
                        Expr = e;
                        loc  = e.Location;
                        
                        if (e_list == null)
                                return;
                        
                        Arguments = new ArrayList (e_list.Count);
                        foreach (Expression tmp in e_list)
                                Arguments.Add (new Argument (tmp, Argument.AType.Expression));
                }

                bool CommonResolve (EmitContext ec)
                {
                        Expr = Expr.Resolve (ec);

                        if (Arguments == null)
                                return false;

                        foreach (Argument a in Arguments){
                                if (!a.Resolve (ec, loc))
                                        return false;
                        }

                        return Expr != null;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (Arguments.Count + 1);
                        args.Add (new Argument (Expr.CreateExpressionTree (ec)));
                        foreach (Argument a in Arguments)
                                args.Add (new Argument (a.Expr.CreateExpressionTree (ec)));

                        return CreateExpressionFactoryCall ("ArrayIndex", args);
                }

                Expression MakePointerAccess (EmitContext ec, Type t)
                {
                        if (Arguments.Count != 1){
                                Error (196, "A pointer must be indexed by only one value");
                                return null;
                        }

                        Expression p = new PointerArithmetic (Binary.Operator.Addition, Expr, ((Argument) Arguments [0]).Expr, t, loc).Resolve (ec);
                        if (p == null)
                                return null;
                        return new Indirection (p, loc).Resolve (ec);
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        if (!CommonResolve (ec))
                                return null;

                        //
                        // We perform some simple tests, and then to "split" the emit and store
                        // code we create an instance of a different class, and return that.
                        //
                        // I am experimenting with this pattern.
                        //
                        Type t = Expr.Type;

                        if (t == TypeManager.array_type){
                                Report.Error (21, loc, "Cannot apply indexing with [] to an expression of type `System.Array'");
                                return null;
                        }
                        
                        if (t.IsArray)
                                return (new ArrayAccess (this, loc)).Resolve (ec);
                        if (t.IsPointer)
                                return MakePointerAccess (ec, t);

                        FieldExpr fe = Expr as FieldExpr;
                        if (fe != null) {
                                IFixedBuffer ff = AttributeTester.GetFixedBuffer (fe.FieldInfo);
                                if (ff != null) {
                                        return MakePointerAccess (ec, ff.ElementType);
                                }
                        }
                        return (new IndexerAccess (this, loc)).Resolve (ec);
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        if (!CommonResolve (ec))
                                return null;

                        type = Expr.Type;
                        if (type.IsArray)
                                return (new ArrayAccess (this, loc)).DoResolveLValue (ec, right_side);

                        if (type.IsPointer)
                                return MakePointerAccess (ec, type);

                        if (Expr.eclass != ExprClass.Variable && TypeManager.IsStruct (type))
                                Error_CannotModifyIntermediateExpressionValue (ec);

                        return (new IndexerAccess (this, loc)).DoResolveLValue (ec, right_side);
                }
                
                public override void Emit (EmitContext ec)
                {
                        throw new Exception ("Should never be reached");
                }

                public override string GetSignatureForError ()
                {
                        return Expr.GetSignatureForError ();
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        ElementAccess target = (ElementAccess) t;

                        target.Expr = Expr.Clone (clonectx);
                        target.Arguments = new ArrayList (Arguments.Count);
                        foreach (Argument a in Arguments)
                                target.Arguments.Add (a.Clone (clonectx));
                }
        }

        /// <summary>
        ///   Implements array access 
        /// </summary>
        public class ArrayAccess : Expression, IAssignMethod, IMemoryLocation {
                //
                // Points to our "data" repository
                //
                ElementAccess ea;

                LocalTemporary temp;

                bool prepared;
                
                public ArrayAccess (ElementAccess ea_data, Location l)
                {
                        ea = ea_data;
                        loc = l;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        return ea.CreateExpressionTree (ec);
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        return DoResolve (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
#if false
                        ExprClass eclass = ea.Expr.eclass;

                        // As long as the type is valid
                        if (!(eclass == ExprClass.Variable || eclass == ExprClass.PropertyAccess ||
                              eclass == ExprClass.Value)) {
                                ea.Expr.Error_UnexpectedKind ("variable or value");
                                return null;
                        }
#endif

                        if (eclass != ExprClass.Invalid)
                                return this;

                        Type t = ea.Expr.Type;
                        int rank = ea.Arguments.Count;
                        if (t.GetArrayRank () != rank) {
                                Report.Error (22, ea.Location, "Wrong number of indexes `{0}' inside [], expected `{1}'",
                                          ea.Arguments.Count.ToString (), t.GetArrayRank ().ToString ());
                                return null;
                        }

                        type = TypeManager.GetElementType (t);
                        if (type.IsPointer && !ec.InUnsafe) {
                                UnsafeError (ea.Location);
                                return null;
                        }

                        foreach (Argument a in ea.Arguments) {
                                a.Expr = ConvertExpressionToArrayIndex (ec, a.Expr);
                        }
                        
                        eclass = ExprClass.Variable;

                        return this;
                }

                /// <summary>
                ///    Emits the right opcode to load an object of Type `t'
                ///    from an array of T
                /// </summary>
                void EmitLoadOpcode (ILGenerator ig, Type type, int rank)
                {
                        if (rank > 1) {
                                MethodInfo get = FetchGetMethod ();
                                ig.Emit (OpCodes.Call, get);
                                return;
                        }

                        if (type == TypeManager.byte_type || type == TypeManager.bool_type)
                                ig.Emit (OpCodes.Ldelem_U1);
                        else if (type == TypeManager.sbyte_type)
                                ig.Emit (OpCodes.Ldelem_I1);
                        else if (type == TypeManager.short_type)
                                ig.Emit (OpCodes.Ldelem_I2);
                        else if (type == TypeManager.ushort_type || type == TypeManager.char_type)
                                ig.Emit (OpCodes.Ldelem_U2);
                        else if (type == TypeManager.int32_type)
                                ig.Emit (OpCodes.Ldelem_I4);
                        else if (type == TypeManager.uint32_type)
                                ig.Emit (OpCodes.Ldelem_U4);
                        else if (type == TypeManager.uint64_type)
                                ig.Emit (OpCodes.Ldelem_I8);
                        else if (type == TypeManager.int64_type)
                                ig.Emit (OpCodes.Ldelem_I8);
                        else if (type == TypeManager.float_type)
                                ig.Emit (OpCodes.Ldelem_R4);
                        else if (type == TypeManager.double_type)
                                ig.Emit (OpCodes.Ldelem_R8);
                        else if (type == TypeManager.intptr_type)
                                ig.Emit (OpCodes.Ldelem_I);
                        else if (TypeManager.IsEnumType (type)){
                                EmitLoadOpcode (ig, TypeManager.GetEnumUnderlyingType (type), rank);
                        } else if (TypeManager.IsStruct (type)){
                                ig.Emit (OpCodes.Ldelema, type);
                                ig.Emit (OpCodes.Ldobj, type);
#if GMCS_SOURCE
                        } else if (type.IsGenericParameter) {
                                ig.Emit (OpCodes.Ldelem, type);
#endif
                        } else if (type.IsPointer)
                                ig.Emit (OpCodes.Ldelem_I);
                        else
                                ig.Emit (OpCodes.Ldelem_Ref);
                }

                protected override void Error_NegativeArrayIndex (Location loc)
                {
                        Report.Warning (251, 2, loc, "Indexing an array with a negative index (array indices always start at zero)");
                }

                /// <summary>
                ///    Returns the right opcode to store an object of Type `t'
                ///    from an array of T.  
                /// </summary>
                static public OpCode GetStoreOpcode (Type t, out bool is_stobj, out bool has_type_arg)
                {
                        //Console.WriteLine (new System.Diagnostics.StackTrace ());
                        has_type_arg = false; is_stobj = false;
                        t = TypeManager.TypeToCoreType (t);
                        if (TypeManager.IsEnumType (t))
                                t = TypeManager.GetEnumUnderlyingType (t);
                        if (t == TypeManager.byte_type || t == TypeManager.sbyte_type ||
                            t == TypeManager.bool_type)
                                return OpCodes.Stelem_I1;
                        else if (t == TypeManager.short_type || t == TypeManager.ushort_type ||
                                 t == TypeManager.char_type)
                                return OpCodes.Stelem_I2;
                        else if (t == TypeManager.int32_type || t == TypeManager.uint32_type)
                                return OpCodes.Stelem_I4;
                        else if (t == TypeManager.int64_type || t == TypeManager.uint64_type)
                                return OpCodes.Stelem_I8;
                        else if (t == TypeManager.float_type)
                                return OpCodes.Stelem_R4;
                        else if (t == TypeManager.double_type)
                                return OpCodes.Stelem_R8;
                        else if (t == TypeManager.intptr_type) {
                                has_type_arg = true;
                                is_stobj = true;
                                return OpCodes.Stobj;
                        } else if (TypeManager.IsStruct (t)) {
                                has_type_arg = true;
                                is_stobj = true;
                                return OpCodes.Stobj;
#if GMCS_SOURCE
                        } else if (t.IsGenericParameter) {
                                has_type_arg = true;
                                return OpCodes.Stelem;
#endif

                        } else if (t.IsPointer)
                                return OpCodes.Stelem_I;
                        else
                                return OpCodes.Stelem_Ref;
                }

                MethodInfo FetchGetMethod ()
                {
                        ModuleBuilder mb = RootContext.ToplevelTypes.Builder;
                        int arg_count = ea.Arguments.Count;
                        Type [] args = new Type [arg_count];
                        MethodInfo get;
                        
                        for (int i = 0; i < arg_count; i++){
                                //args [i++] = a.Type;
                                args [i] = TypeManager.int32_type;
                        }
                        
                        get = mb.GetArrayMethod (
                                ea.Expr.Type, "Get",
                                CallingConventions.HasThis |
                                CallingConventions.Standard,
                                type, args);
                        return get;
                }
                                

                MethodInfo FetchAddressMethod ()
                {
                        ModuleBuilder mb = RootContext.ToplevelTypes.Builder;
                        int arg_count = ea.Arguments.Count;
                        Type [] args = new Type [arg_count];
                        MethodInfo address;
                        Type ret_type;
                        
                        ret_type = TypeManager.GetReferenceType (type);
                        
                        for (int i = 0; i < arg_count; i++){
                                //args [i++] = a.Type;
                                args [i] = TypeManager.int32_type;
                        }
                        
                        address = mb.GetArrayMethod (
                                ea.Expr.Type, "Address",
                                CallingConventions.HasThis |
                                CallingConventions.Standard,
                                ret_type, args);

                        return address;
                }

                //
                // Load the array arguments into the stack.
                //
                void LoadArrayAndArguments (EmitContext ec)
                {
                        ea.Expr.Emit (ec);

                        for (int i = 0; i < ea.Arguments.Count; ++i) {
                                ((Argument)ea.Arguments [i]).Emit (ec);
                        }
                }

                public void Emit (EmitContext ec, bool leave_copy)
                {
                        int rank = ea.Expr.Type.GetArrayRank ();
                        ILGenerator ig = ec.ig;

                        if (prepared) {
                                LoadFromPtr (ig, this.type);
                        } else {
                                LoadArrayAndArguments (ec);
                                EmitLoadOpcode (ig, type, rank);
                        }       

                        if (leave_copy) {
                                ig.Emit (OpCodes.Dup);
                                temp = new LocalTemporary (this.type);
                                temp.Store (ec);
                        }
                }
                
                public override void Emit (EmitContext ec)
                {
                        Emit (ec, false);
                }

                public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
                {
                        int rank = ea.Expr.Type.GetArrayRank ();
                        ILGenerator ig = ec.ig;
                        Type t = source.Type;
                        prepared = prepare_for_load;

                        if (prepared) {
                                AddressOf (ec, AddressOp.LoadStore);
                                ec.ig.Emit (OpCodes.Dup);
                        } else {
                                LoadArrayAndArguments (ec);
                        }

                        if (rank == 1) {
                                bool is_stobj, has_type_arg;
                                OpCode op = GetStoreOpcode (t, out is_stobj, out has_type_arg);

                                if (!prepared) {
                                        //
                                        // The stobj opcode used by value types will need
                                        // an address on the stack, not really an array/array
                                        // pair
                                        //
                                        if (is_stobj)
                                                ig.Emit (OpCodes.Ldelema, t);
                                }
                                
                                source.Emit (ec);
                                if (leave_copy) {
                                        ec.ig.Emit (OpCodes.Dup);
                                        temp = new LocalTemporary (this.type);
                                        temp.Store (ec);
                                }
                                
                                if (prepared)
                                        StoreFromPtr (ig, t);
                                else if (is_stobj)
                                        ig.Emit (OpCodes.Stobj, t);
                                else if (has_type_arg)
                                        ig.Emit (op, t);
                                else
                                        ig.Emit (op);
                        } else {
                                source.Emit (ec);
                                if (leave_copy) {
                                        ec.ig.Emit (OpCodes.Dup);
                                        temp = new LocalTemporary (this.type);
                                        temp.Store (ec);
                                }

                                if (prepared) {
                                        StoreFromPtr (ig, t);
                                } else {
                                        int arg_count = ea.Arguments.Count;
                                        Type [] args = new Type [arg_count + 1];
                                        for (int i = 0; i < arg_count; i++) {
                                                //args [i++] = a.Type;
                                                args [i] = TypeManager.int32_type;
                                        }
                                        args [arg_count] = type;

                                        MethodInfo set = RootContext.ToplevelTypes.Builder.GetArrayMethod (
                                                ea.Expr.Type, "Set",
                                                CallingConventions.HasThis |
                                                CallingConventions.Standard,
                                                TypeManager.void_type, args);

                                        ig.Emit (OpCodes.Call, set);
                                }
                        }
                        
                        if (temp != null) {
                                temp.Emit (ec);
                                temp.Release (ec);
                        }
                }

                public void EmitNew (EmitContext ec, New source, bool leave_copy)
                {
                        if (!source.Emit (ec, this)) {
                                if (leave_copy)
                                        throw new NotImplementedException ();

                                return;
                        }

                        throw new NotImplementedException ();
                }

                public void AddressOf (EmitContext ec, AddressOp mode)
                {
                        int rank = ea.Expr.Type.GetArrayRank ();
                        ILGenerator ig = ec.ig;

                        LoadArrayAndArguments (ec);

                        if (rank == 1){
                                ig.Emit (OpCodes.Ldelema, type);
                        } else {
                                MethodInfo address = FetchAddressMethod ();
                                ig.Emit (OpCodes.Call, address);
                        }
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        type = storey.MutateType (type);
                        ea.Expr.Type = storey.MutateType (ea.Expr.Type);
                }
        }

        /// <summary>
        ///   Expressions that represent an indexer call.
        /// </summary>
        public class IndexerAccess : Expression, IAssignMethod
        {
                class IndexerMethodGroupExpr : MethodGroupExpr
                {
                        public IndexerMethodGroupExpr (Indexers indexers, Location loc)
                                : base (null, loc)
                        {
                                Methods = (MethodBase []) indexers.Methods.ToArray (typeof (MethodBase));
                        }

                        public override string Name {
                                get {
                                        return "this";
                                }
                        }

                        protected override int GetApplicableParametersCount (MethodBase method, AParametersCollection parameters)
                        {
                                //
                                // Here is the trick, decrease number of arguments by 1 when only
                                // available property method is setter. This makes overload resolution
                                // work correctly for indexers.
                                //
                                
                                if (method.Name [0] == 'g')
                                        return parameters.Count;

                                return parameters.Count - 1;
                        }
                }

                class Indexers
                {
                        // Contains either property getter or setter
                        public ArrayList Methods;
                        public ArrayList Properties;

                        Indexers ()
                        {
                        }

                        void Append (Type caller_type, MemberInfo [] mi)
                        {
                                if (mi == null)
                                        return;

                                foreach (PropertyInfo property in mi) {
                                        MethodInfo accessor = property.GetGetMethod (true);
                                        if (accessor == null)
                                                accessor = property.GetSetMethod (true);

                                        if (Methods == null) {
                                                Methods = new ArrayList ();
                                                Properties = new ArrayList ();
                                        }

                                        Methods.Add (accessor);
                                        Properties.Add (property);
                                }
                        }

                        static MemberInfo [] GetIndexersForTypeOrInterface (Type caller_type, Type lookup_type)
                        {
                                string p_name = TypeManager.IndexerPropertyName (lookup_type);

                                return TypeManager.MemberLookup (
                                        caller_type, caller_type, lookup_type, MemberTypes.Property,
                                        BindingFlags.Public | BindingFlags.Instance |
                                        BindingFlags.DeclaredOnly, p_name, null);
                        }
                        
                        public static Indexers GetIndexersForType (Type caller_type, Type lookup_type) 
                        {
                                Indexers ix = new Indexers ();

                                if (TypeManager.IsGenericParameter (lookup_type)) {
                                        GenericConstraints gc = TypeManager.GetTypeParameterConstraints (lookup_type);
                                        if (gc == null)
                                                return ix;

                                        if (gc.HasClassConstraint) {
                                                Type class_contraint = gc.ClassConstraint;
                                                while (class_contraint != TypeManager.object_type && class_contraint != null) {
                                                        ix.Append (caller_type, GetIndexersForTypeOrInterface (caller_type, class_contraint));
                                                        class_contraint = class_contraint.BaseType;
                                                }
                                        }

                                        Type[] ifaces = gc.InterfaceConstraints;
                                        foreach (Type itype in ifaces)
                                                ix.Append (caller_type, GetIndexersForTypeOrInterface (caller_type, itype));

                                        return ix;
                                }

                                Type copy = lookup_type;
                                while (copy != TypeManager.object_type && copy != null){
                                        ix.Append (caller_type, GetIndexersForTypeOrInterface (caller_type, copy));
                                        copy = copy.BaseType;
                                }

                                if (lookup_type.IsInterface) {
                                        Type [] ifaces = TypeManager.GetInterfaces (lookup_type);
                                        if (ifaces != null) {
                                                foreach (Type itype in ifaces)
                                                        ix.Append (caller_type, GetIndexersForTypeOrInterface (caller_type, itype));
                                        }
                                }

                                return ix;
                        }
                }

                enum AccessorType
                {
                        Get,
                        Set
                }

                //
                // Points to our "data" repository
                //
                MethodInfo get, set;
                bool is_base_indexer;
                bool prepared;
                LocalTemporary temp;
                LocalTemporary prepared_value;
                Expression set_expr;

                protected Type indexer_type;
                protected Type current_type;
                protected Expression instance_expr;
                protected ArrayList arguments;
                
                public IndexerAccess (ElementAccess ea, Location loc)
                        : this (ea.Expr, false, loc)
                {
                        this.arguments = ea.Arguments;
                }

                protected IndexerAccess (Expression instance_expr, bool is_base_indexer,
                                         Location loc)
                {
                        this.instance_expr = instance_expr;
                        this.is_base_indexer = is_base_indexer;
                        this.eclass = ExprClass.Value;
                        this.loc = loc;
                }

                static string GetAccessorName (AccessorType at)
                {
                        if (at == AccessorType.Set)
                                return "set";

                        if (at == AccessorType.Get)
                                return "get";

                        throw new NotImplementedException (at.ToString ());
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (arguments.Count + 2);
                        args.Add (new Argument (instance_expr.CreateExpressionTree (ec)));
                        args.Add (new Argument (new TypeOfMethodInfo (get, loc)));
                        foreach (Argument a in arguments)
                                args.Add (new Argument (a.Expr.CreateExpressionTree (ec)));

                        return CreateExpressionFactoryCall ("Call", args);
                }

                protected virtual bool CommonResolve (EmitContext ec)
                {
                        indexer_type = instance_expr.Type;
                        current_type = ec.ContainerType;

                        return true;
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        return ResolveAccessor (ec, AccessorType.Get);
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        if (right_side == EmptyExpression.OutAccess) {
                                Report.Error (206, loc, "A property or indexer `{0}' may not be passed as an out or ref parameter",
                                              GetSignatureForError ());
                                return null;
                        }

                        // if the indexer returns a value type, and we try to set a field in it
                        if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
                                Error_CannotModifyIntermediateExpressionValue (ec);
                        }

                        Expression e = ResolveAccessor (ec, AccessorType.Set);
                        if (e == null)
                                return null;

                        set_expr = Convert.ImplicitConversion (ec, right_side, type, loc);
                        return e;
                }

                Expression ResolveAccessor (EmitContext ec, AccessorType accessorType)
                {
                        if (!CommonResolve (ec))
                                return null;

                        Indexers ilist = Indexers.GetIndexersForType (current_type, indexer_type);
                        if (ilist.Methods == null) {
                                Report.Error (21, loc, "Cannot apply indexing with [] to an expression of type `{0}'",
                                                  TypeManager.CSharpName (indexer_type));
                                return null;
                        }

                        MethodGroupExpr mg = new IndexerMethodGroupExpr (ilist, loc);
                        mg = mg.OverloadResolve (ec, ref arguments, false, loc);
                        if (mg == null)
                                return null;

                        MethodInfo mi = (MethodInfo) mg;
                        PropertyInfo pi = null;
                        for (int i = 0; i < ilist.Methods.Count; ++i) {
                                if (ilist.Methods [i] == mi) {
                                        pi = (PropertyInfo) ilist.Properties [i];
                                        break;
                                }
                        }

                        type = TypeManager.TypeToCoreType (pi.PropertyType);
                        if (type.IsPointer && !ec.InUnsafe)
                                UnsafeError (loc);

                        MethodInfo accessor;
                        if (accessorType == AccessorType.Get) {
                                accessor = get = pi.GetGetMethod (true);
                        } else {
                                accessor = set = pi.GetSetMethod (true);
                                if (accessor == null && pi.GetGetMethod (true) != null) {
                                        Report.SymbolRelatedToPreviousError (pi);
                                        Report.Error (200, loc, "The read only property or indexer `{0}' cannot be assigned to",
                                                TypeManager.GetFullNameSignature (pi));
                                        return null;
                                }
                        }

                        if (accessor == null) {
                                Report.SymbolRelatedToPreviousError (pi);
                                Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks a `{1}' accessor",
                                        TypeManager.GetFullNameSignature (pi), GetAccessorName (accessorType));
                                return null;
                        }

                        //
                        // Only base will allow this invocation to happen.
                        //
                        if (accessor.IsAbstract && this is BaseIndexerAccess) {
                                Error_CannotCallAbstractBase (TypeManager.GetFullNameSignature (pi));
                        }

                        bool must_do_cs1540_check;
                        if (!IsAccessorAccessible (ec.ContainerType, accessor, out must_do_cs1540_check)) {
                                if (set == null)
                                        set = pi.GetSetMethod (true);
                                else
                                        get = pi.GetGetMethod (true);

                                if (set != null && get != null &&
                                        (set.Attributes & MethodAttributes.MemberAccessMask) != (get.Attributes & MethodAttributes.MemberAccessMask)) {
                                        Report.SymbolRelatedToPreviousError (accessor);
                                        Report.Error (271, loc, "The property or indexer `{0}' cannot be used in this context because a `{1}' accessor is inaccessible",
                                                TypeManager.GetFullNameSignature (pi), GetAccessorName (accessorType));
                                } else {
                                        Report.SymbolRelatedToPreviousError (pi);
                                        ErrorIsInaccesible (loc, TypeManager.GetFullNameSignature (pi));
                                }
                        }

                        instance_expr.CheckMarshalByRefAccess (ec);
                        eclass = ExprClass.IndexerAccess;
                        return this;
                }
                
                public void Emit (EmitContext ec, bool leave_copy)
                {
                        if (prepared) {
                                prepared_value.Emit (ec);
                        } else {
                                Invocation.EmitCall (ec, is_base_indexer, instance_expr, get,
                                        arguments, loc, false, false);
                        }

                        if (leave_copy) {
                                ec.ig.Emit (OpCodes.Dup);
                                temp = new LocalTemporary (Type);
                                temp.Store (ec);
                        }
                }
                
                //
                // source is ignored, because we already have a copy of it from the
                // LValue resolution and we have already constructed a pre-cached
                // version of the arguments (ea.set_arguments);
                //
                public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
                {
                        prepared = prepare_for_load;
                        Expression value = set_expr;

                        if (prepared) {
                                Invocation.EmitCall (ec, is_base_indexer, instance_expr, get,
                                        arguments, loc, true, false);

                                prepared_value = new LocalTemporary (type);
                                prepared_value.Store (ec);
                                source.Emit (ec);
                                prepared_value.Release (ec);

                                if (leave_copy) {
                                        ec.ig.Emit (OpCodes.Dup);
                                        temp = new LocalTemporary (Type);
                                        temp.Store (ec);
                                }
                        } else if (leave_copy) {
                                temp = new LocalTemporary (Type);
                                source.Emit (ec);
                                temp.Store (ec);
                                value = temp;
                        }
                        
                        arguments.Add (new Argument (value, Argument.AType.Expression));
                        Invocation.EmitCall (ec, is_base_indexer, instance_expr, set, arguments, loc, false, prepared);
                        
                        if (temp != null) {
                                temp.Emit (ec);
                                temp.Release (ec);
                        }
                }
                
                public override void Emit (EmitContext ec)
                {
                        Emit (ec, false);
                }

                public override string GetSignatureForError ()
                {
                        return TypeManager.CSharpSignature (get != null ? get : set, false);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        if (get != null)
                                get = storey.MutateGenericMethod (get);
                        if (set != null)
                                set = storey.MutateGenericMethod (set);

                        instance_expr.MutateHoistedGenericType (storey);
                        foreach (Argument a in arguments)
                                a.Expr.MutateHoistedGenericType (storey);

                        type = storey.MutateType (type);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        IndexerAccess target = (IndexerAccess) t;

                        if (arguments != null){
                                target.arguments = new ArrayList ();
                                foreach (Argument a in arguments)
                                        target.arguments.Add (a.Clone (clonectx));
                        }
                        if (instance_expr != null)
                                target.instance_expr = instance_expr.Clone (clonectx);
                }
        }

        /// <summary>
        ///   The base operator for method names
        /// </summary>
        public class BaseAccess : Expression {
                public readonly string Identifier;
                TypeArguments args;

                public BaseAccess (string member, Location l)
                {
                        this.Identifier = member;
                        loc = l;
                }

                public BaseAccess (string member, TypeArguments args, Location l)
                        : this (member, l)
                {
                        this.args = args;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        Expression c = CommonResolve (ec);

                        if (c == null)
                                return null;

                        //
                        // MethodGroups use this opportunity to flag an error on lacking ()
                        //
                        if (!(c is MethodGroupExpr))
                                return c.Resolve (ec);
                        return c;
                }

                public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                {
                        Expression c = CommonResolve (ec);

                        if (c == null)
                                return null;

                        //
                        // MethodGroups use this opportunity to flag an error on lacking ()
                        //
                        if (! (c is MethodGroupExpr))
                                return c.DoResolveLValue (ec, right_side);

                        return c;
                }

                Expression CommonResolve (EmitContext ec)
                {
                        Expression member_lookup;
                        Type current_type = ec.ContainerType;
                        Type base_type = current_type.BaseType;

                        if (!This.IsThisAvailable (ec)) {
                                if (ec.IsStatic) {
                                        Error (1511, "Keyword `base' is not available in a static method");
                                } else {
                                        Error (1512, "Keyword `base' is not available in the current context");
                                }
                                return null;
                        }
                        
                        member_lookup = MemberLookup (ec.ContainerType, null, base_type, Identifier,
                                                      AllMemberTypes, AllBindingFlags, loc);
                        if (member_lookup == null) {
                                Error_MemberLookupFailed (ec.ContainerType, base_type, base_type, Identifier,
                                        null, AllMemberTypes, AllBindingFlags);
                                return null;
                        }

                        Expression left;
                        
                        if (ec.IsStatic)
                                left = new TypeExpression (base_type, loc);
                        else
                                left = ec.GetThis (loc);

                        MemberExpr me = (MemberExpr) member_lookup;
                        me = me.ResolveMemberAccess (ec, left, loc, null);
                        if (me == null)
                                return null;

                        me.IsBase = true;
                        if (args != null) {
                                args.Resolve (ec);
                                me.SetTypeArguments (args);
                        }

                        return me;
                }

                public override void Emit (EmitContext ec)
                {
                        throw new Exception ("Should never be called"); 
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        BaseAccess target = (BaseAccess) t;

                        if (args != null)
                                target.args = args.Clone ();
                }
        }

        /// <summary>
        ///   The base indexer operator
        /// </summary>
        public class BaseIndexerAccess : IndexerAccess {
                public BaseIndexerAccess (ArrayList args, Location loc)
                        : base (null, true, loc)
                {
                        arguments = new ArrayList ();
                        foreach (Expression tmp in args)
                                arguments.Add (new Argument (tmp, Argument.AType.Expression));
                }

                protected override bool CommonResolve (EmitContext ec)
                {
                        instance_expr = ec.GetThis (loc);

                        current_type = ec.ContainerType.BaseType;
                        indexer_type = current_type;

                        foreach (Argument a in arguments){
                                if (!a.Resolve (ec, loc))
                                        return false;
                        }

                        return true;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        MemberExpr.Error_BaseAccessInExpressionTree (loc);
                        return base.CreateExpressionTree (ec);
                }
        }
        
        /// <summary>
        ///   This class exists solely to pass the Type around and to be a dummy
        ///   that can be passed to the conversion functions (this is used by
        ///   foreach implementation to typecast the object return value from
        ///   get_Current into the proper type.  All code has been generated and
        ///   we only care about the side effect conversions to be performed
        ///
        ///   This is also now used as a placeholder where a no-action expression
        ///   is needed (the `New' class).
        /// </summary>
        public class EmptyExpression : Expression {
                public static readonly Expression Null = new EmptyExpression ();

                public static readonly EmptyExpression OutAccess = new EmptyExpression ();
                public static readonly EmptyExpression LValueMemberAccess = new EmptyExpression ();
                public static readonly EmptyExpression LValueMemberOutAccess = new EmptyExpression ();
                public static readonly EmptyExpression UnaryAddress = new EmptyExpression ();

                static EmptyExpression temp = new EmptyExpression ();
                public static EmptyExpression Grab ()
                {
                        EmptyExpression retval = temp == null ? new EmptyExpression () : temp;
                        temp = null;
                        return retval;
                }

                public static void Release (EmptyExpression e)
                {
                        temp = e;
                }

                EmptyExpression ()
                {
                        // FIXME: Don't set to object
                        type = TypeManager.object_type;
                        eclass = ExprClass.Value;
                        loc = Location.Null;
                }

                public EmptyExpression (Type t)
                {
                        type = t;
                        eclass = ExprClass.Value;
                        loc = Location.Null;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        // nothing, as we only exist to not do anything.
                }

                public override void EmitSideEffect (EmitContext ec)
                {
                }

                //
                // This is just because we might want to reuse this bad boy
                // instead of creating gazillions of EmptyExpressions.
                // (CanImplicitConversion uses it)
                //
                public void SetType (Type t)
                {
                        type = t;
                }
        }
        
        //
        // Empty statement expression
        //
        public sealed class EmptyExpressionStatement : ExpressionStatement
        {
                public static readonly EmptyExpressionStatement Instance = new EmptyExpressionStatement ();

                private EmptyExpressionStatement ()
                {
                        eclass = ExprClass.Value;
                        loc = Location.Null;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        return null;
                }

                public override void EmitStatement (EmitContext ec)
                {
                        // Do nothing
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        type = TypeManager.object_type;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        // Do nothing
                }
        }       

        public class UserCast : Expression {
                MethodInfo method;
                Expression source;
                
                public UserCast (MethodInfo method, Expression source, Location l)
                {
                        this.method = method;
                        this.source = source;
                        type = TypeManager.TypeToCoreType (method.ReturnType);
                        loc = l;
                }

                public Expression Source {
                        get {
                                return source;
                        }
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (3);
                        args.Add (new Argument (source.CreateExpressionTree (ec)));
                        args.Add (new Argument (new TypeOf (new TypeExpression (type, loc), loc)));
                        args.Add (new Argument (new TypeOfMethodInfo (method, loc)));
                        return CreateExpressionFactoryCall ("Convert", args);
                }
                        
                public override Expression DoResolve (EmitContext ec)
                {
                        ObsoleteAttribute oa = AttributeTester.GetMethodObsoleteAttribute (method);
                        if (oa != null)
                                AttributeTester.Report_ObsoleteMessage (oa, GetSignatureForError (), loc);

                        eclass = ExprClass.Value;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        source.Emit (ec);
                        ec.ig.Emit (OpCodes.Call, method);
                }

                public override string GetSignatureForError ()
                {
                        return TypeManager.CSharpSignature (method);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        source.MutateHoistedGenericType (storey);
                        method = storey.MutateGenericMethod (method);
                }
        }

        // <summary>
        //   This class is used to "construct" the type during a typecast
        //   operation.  Since the Type.GetType class in .NET can parse
        //   the type specification, we just use this to construct the type
        //   one bit at a time.
        // </summary>
        public class ComposedCast : TypeExpr {
                FullNamedExpression left;
                string dim;
                
                public ComposedCast (FullNamedExpression left, string dim)
                        : this (left, dim, left.Location)
                {
                }

                public ComposedCast (FullNamedExpression left, string dim, Location l)
                {
                        this.left = left;
                        this.dim = dim;
                        loc = l;
                }

                protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
                {
                        TypeExpr lexpr = left.ResolveAsTypeTerminal (ec, false);
                        if (lexpr == null)
                                return null;

                        Type ltype = lexpr.Type;
                        if ((dim.Length > 0) && (dim [0] == '?')) {
                                TypeExpr nullable = new Nullable.NullableType (lexpr, loc);
                                if (dim.Length > 1)
                                        nullable = new ComposedCast (nullable, dim.Substring (1), loc);
                                return nullable.ResolveAsTypeTerminal (ec, false);
                        }

                        if (dim == "*" && !TypeManager.VerifyUnManaged (ltype, loc))
                                return null;

                        if (dim.Length != 0 && dim [0] == '[') {
                                if (TypeManager.IsSpecialType (ltype)) {
                                        Report.Error (611, loc, "Array elements cannot be of type `{0}'", TypeManager.CSharpName (ltype));
                                        return null;
                                }

                                if ((ltype.Attributes & Class.StaticClassAttribute) == Class.StaticClassAttribute) {
                                        Report.SymbolRelatedToPreviousError (ltype);
                                        Report.Error (719, loc, "Array elements cannot be of static type `{0}'", 
                                                TypeManager.CSharpName (ltype));
                                }
                        }

                        if (dim != "")
                                type = TypeManager.GetConstructedType (ltype, dim);
                        else
                                type = ltype;

                        if (type == null)
                                throw new InternalErrorException ("Couldn't create computed type " + ltype + dim);

                        if (type.IsPointer && !ec.IsInUnsafeScope){
                                UnsafeError (loc);
                        }

                        eclass = ExprClass.Type;
                        return this;
                }

                public override string GetSignatureForError ()
                {
                        return left.GetSignatureForError () + dim;
                }

                public override TypeExpr ResolveAsTypeTerminal (IResolveContext ec, bool silent)
                {
                        return ResolveAsBaseTerminal (ec, silent);
                }               
        }

        public class FixedBufferPtr : Expression {
                Expression array;

                public FixedBufferPtr (Expression array, Type array_type, Location l)
                {
                        this.array = array;
                        this.loc = l;

                        type = TypeManager.GetPointerType (array_type);
                        eclass = ExprClass.Value;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        Error_PointerInsideExpressionTree ();
                        return null;
                }

                public override void Emit(EmitContext ec)
                {
                        array.Emit (ec);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        //
                        // We are born fully resolved
                        //
                        return this;
                }
        }


        //
        // This class is used to represent the address of an array, used
        // only by the Fixed statement, this generates "&a [0]" construct
        // for fixed (char *pa = a)
        //
        public class ArrayPtr : FixedBufferPtr {
                Type array_type;
                
                public ArrayPtr (Expression array, Type array_type, Location l):
                        base (array, array_type, l)
                {
                        this.array_type = array_type;
                }

                public override void Emit (EmitContext ec)
                {
                        base.Emit (ec);
                        
                        ILGenerator ig = ec.ig;
                        IntLiteral.EmitInt (ig, 0);
                        ig.Emit (OpCodes.Ldelema, array_type);
                }
        }

        //
        // Encapsulates a conversion rules required for array indexes
        //
        public class ArrayIndexCast : TypeCast
        {
                public ArrayIndexCast (Expression expr)
                        : base (expr, expr.Type)
                {
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (child.CreateExpressionTree (ec)));
                        args.Add (new Argument (new TypeOf (new TypeExpression (TypeManager.int32_type, loc), loc)));
                        return CreateExpressionFactoryCall ("ConvertChecked", args);
                }

                public override void Emit (EmitContext ec)
                {
                        child.Emit (ec);
                                
                        if (type == TypeManager.int32_type)
                                return;

                        if (type == TypeManager.uint32_type)
                                ec.ig.Emit (OpCodes.Conv_U);
                        else if (type == TypeManager.int64_type)
                                ec.ig.Emit (OpCodes.Conv_Ovf_I);
                        else if (type == TypeManager.uint64_type)
                                ec.ig.Emit (OpCodes.Conv_Ovf_I_Un);
                        else
                                throw new InternalErrorException ("Cannot emit cast to unknown array element type", type);
                }
        }

        //
        // Implements the `stackalloc' keyword
        //
        public class StackAlloc : Expression {
                Type otype;
                Expression t;
                Expression count;
                
                public StackAlloc (Expression type, Expression count, Location l)
                {
                        t = type;
                        this.count = count;
                        loc = l;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        count = count.Resolve (ec);
                        if (count == null)
                                return null;
                        
                        if (count.Type != TypeManager.uint32_type){
                                count = Convert.ImplicitConversionRequired (ec, count, TypeManager.int32_type, loc);
                                if (count == null)
                                        return null;
                        }

                        Constant c = count as Constant;
                        if (c != null && c.IsNegative) {
                                Report.Error (247, loc, "Cannot use a negative size with stackalloc");
                                return null;
                        }

                        if (ec.InCatch || ec.InFinally) {
                                Error (255, "Cannot use stackalloc in finally or catch");
                                return null;
                        }

                        TypeExpr texpr = t.ResolveAsTypeTerminal (ec, false);
                        if (texpr == null)
                                return null;

                        otype = texpr.Type;

                        if (!TypeManager.VerifyUnManaged (otype, loc))
                                return null;

                        type = TypeManager.GetPointerType (otype);
                        eclass = ExprClass.Value;

                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        int size = GetTypeSize (otype);
                        ILGenerator ig = ec.ig;

                        count.Emit (ec);

                        if (size == 0)
                                ig.Emit (OpCodes.Sizeof, otype);
                        else
                                IntConstant.EmitInt (ig, size);

                        ig.Emit (OpCodes.Mul_Ovf_Un);
                        ig.Emit (OpCodes.Localloc);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        StackAlloc target = (StackAlloc) t;
                        target.count = count.Clone (clonectx);
                        target.t = t.Clone (clonectx);
                }
        }

        //
        // An object initializer expression
        //
        public class ElementInitializer : Assign
        {
                public readonly string Name;

                public ElementInitializer (string name, Expression initializer, Location loc)
                        : base (null, initializer, loc)
                {
                        this.Name = name;
                }
                
                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        ElementInitializer target = (ElementInitializer) t;
                        target.source = source.Clone (clonectx);
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        FieldExpr fe = target as FieldExpr;
                        if (fe != null)
                                args.Add (new Argument (fe.CreateTypeOfExpression ()));
                        else
                                args.Add (new Argument (((PropertyExpr)target).CreateSetterTypeOfExpression ()));

                        args.Add (new Argument (source.CreateExpressionTree (ec)));
                        return CreateExpressionFactoryCall (
                                source is CollectionOrObjectInitializers ? "ListBind" : "Bind",
                                args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (source == null)
                                return EmptyExpressionStatement.Instance;
                        
                        MemberExpr me = MemberLookupFinal (ec, ec.CurrentInitializerVariable.Type, ec.CurrentInitializerVariable.Type,
                                Name, MemberTypes.Field | MemberTypes.Property, BindingFlags.Public | BindingFlags.Instance, loc) as MemberExpr;

                        if (me == null)
                                return null;

                        target = me;
                        me.InstanceExpression = ec.CurrentInitializerVariable;

                        if (source is CollectionOrObjectInitializers) {
                                Expression previous = ec.CurrentInitializerVariable;
                                ec.CurrentInitializerVariable = target;
                                source = source.Resolve (ec);
                                ec.CurrentInitializerVariable = previous;
                                if (source == null)
                                        return null;
                                        
                                eclass = source.eclass;
                                type = source.Type;
                                return this;
                        }

                        Expression expr = base.DoResolve (ec);
                        if (expr == null)
                                return null;

                        //
                        // Ignore field initializers with default value
                        //
                        Constant c = source as Constant;
                        if (c != null && c.IsDefaultInitializer (type) && target.eclass == ExprClass.Variable)
                                return EmptyExpressionStatement.Instance.DoResolve (ec);

                        return expr;
                }

                protected override Expression Error_MemberLookupFailed (Type type, MemberInfo[] members)
                {
                        MemberInfo member = members [0];
                        if (member.MemberType != MemberTypes.Property && member.MemberType != MemberTypes.Field)
                                Report.Error (1913, loc, "Member `{0}' cannot be initialized. An object " +
                                        "initializer may only be used for fields, or properties", TypeManager.GetFullNameSignature (member));
                        else
                                Report.Error (1914, loc, " Static field or property `{0}' cannot be assigned in an object initializer",
                                        TypeManager.GetFullNameSignature (member));

                        return null;
                }
                
                public override void EmitStatement (EmitContext ec)
                {
                        if (source is CollectionOrObjectInitializers)
                                source.Emit (ec);
                        else
                                base.EmitStatement (ec);
                }
        }
        
        //
        // A collection initializer expression
        //
        public class CollectionElementInitializer : Invocation
        {
                public class ElementInitializerArgument : Argument
                {
                        public ElementInitializerArgument (Expression e)
                                : base (e)
                        {
                        }
                }

                sealed class AddMemberAccess : MemberAccess
                {
                        public AddMemberAccess (Expression expr, Location loc)
                                : base (expr, "Add", loc)
                        {
                        }

                        protected override void Error_TypeDoesNotContainDefinition (Type type, string name)
                        {
                                if (TypeManager.HasElementType (type))
                                        return;

                                base.Error_TypeDoesNotContainDefinition (type, name);
                        }
                }

                public CollectionElementInitializer (Expression argument)
                        : base (null, new ArrayList (1), true)
                {
                        Arguments.Add (argument);
                        this.loc = argument.Location;
                }

                public CollectionElementInitializer (ArrayList arguments, Location loc)
                        : base (null, arguments, true)
                {
                        this.loc = loc;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (mg.CreateExpressionTree (ec)));

                        ArrayList expr_initializers = new ArrayList (Arguments.Count);
                        foreach (Argument a in Arguments)
                                expr_initializers.Add (a.Expr.CreateExpressionTree (ec));

                        args.Add (new Argument (new ArrayCreation (
                                CreateExpressionTypeExpression (loc), "[]", expr_initializers, loc)));
                        return CreateExpressionFactoryCall ("ElementInit", args);
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        CollectionElementInitializer target = (CollectionElementInitializer) t;

                        target.Arguments = new ArrayList (Arguments.Count);
                        foreach (Expression e in Arguments)
                                target.Arguments.Add (e.Clone (clonectx));
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (eclass != ExprClass.Invalid)
                                return this;

                        // TODO: We could call a constructor which takes element count argument,
                        // for known types like List<T>, Dictionary<T, U>
                        
                        for (int i = 0; i < Arguments.Count; ++i) {
                                Expression expr = Arguments [i] as Expression;
                                if (expr == null)
                                        return null;

                                expr = expr.Resolve (ec);
                                if (expr == null)
                                        return null;

                                Arguments [i] = new ElementInitializerArgument (expr);
                        }

                        base.expr = new AddMemberAccess (ec.CurrentInitializerVariable, loc);

                        return base.DoResolve (ec);
                }
        }
        
        //
        // A block of object or collection initializers
        //
        public class CollectionOrObjectInitializers : ExpressionStatement
        {
                ArrayList initializers;
                bool is_collection_initialization;
                
                public static readonly CollectionOrObjectInitializers Empty = 
                        new CollectionOrObjectInitializers (new ArrayList (0), Location.Null);

                public CollectionOrObjectInitializers (ArrayList initializers, Location loc)
                {
                        this.initializers = initializers;
                        this.loc = loc;
                }
                
                public bool IsEmpty {
                        get {
                                return initializers.Count == 0;
                        }
                }

                public bool IsCollectionInitializer {
                        get {
                                return is_collection_initialization;
                        }
                }

                protected override void CloneTo (CloneContext clonectx, Expression target)
                {
                        CollectionOrObjectInitializers t = (CollectionOrObjectInitializers) target;

                        t.initializers = new ArrayList (initializers.Count);
                        foreach (Expression e in initializers)
                                t.initializers.Add (e.Clone (clonectx));
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList expr_initializers = new ArrayList (initializers.Count);
                        foreach (Expression e in initializers) {
                                Expression expr = e.CreateExpressionTree (ec);
                                if (expr != null)
                                        expr_initializers.Add (expr);
                        }

                        return new ImplicitlyTypedArrayCreation ("[]", expr_initializers, loc);
                }
                
                public override Expression DoResolve (EmitContext ec)
                {
                        if (eclass != ExprClass.Invalid)
                                return this;

                        ArrayList element_names = null;
                        for (int i = 0; i < initializers.Count; ++i) {
                                Expression initializer = (Expression) initializers [i];
                                ElementInitializer element_initializer = initializer as ElementInitializer;

                                if (i == 0) {
                                        if (element_initializer != null) {
                                                element_names = new ArrayList (initializers.Count);
                                                element_names.Add (element_initializer.Name);
                                        } else if (initializer is CompletingExpression){
                                                initializer.Resolve (ec);
                                                throw new InternalErrorException ("This line should never be reached");
                                        } else {
                                                if (!TypeManager.ImplementsInterface (ec.CurrentInitializerVariable.Type, TypeManager.ienumerable_type)) {
                                                        Report.Error (1922, loc, "A field or property `{0}' cannot be initialized with a collection " +
                                                                "object initializer because type `{1}' does not implement `{2}' interface",
                                                                ec.CurrentInitializerVariable.GetSignatureForError (),
                                                                TypeManager.CSharpName (ec.CurrentInitializerVariable.Type),
                                                                TypeManager.CSharpName (TypeManager.ienumerable_type));
                                                        return null;
                                                }
                                                is_collection_initialization = true;
                                        }
                                } else {
                                        if (is_collection_initialization != (element_initializer == null)) {
                                                Report.Error (747, initializer.Location, "Inconsistent `{0}' member declaration",
                                                        is_collection_initialization ? "collection initializer" : "object initializer");
                                                continue;
                                        }

                                        if (!is_collection_initialization) {
                                                if (element_names.Contains (element_initializer.Name)) {
                                                        Report.Error (1912, element_initializer.Location,
                                                                "An object initializer includes more than one member `{0}' initialization",
                                                                element_initializer.Name);
                                                } else {
                                                        element_names.Add (element_initializer.Name);
                                                }
                                        }
                                }

                                Expression e = initializer.Resolve (ec);
                                if (e == EmptyExpressionStatement.Instance)
                                        initializers.RemoveAt (i--);
                                else
                                        initializers [i] = e;
                        }

                        type = ec.CurrentInitializerVariable.Type;
                        if (is_collection_initialization) {
                                if (TypeManager.HasElementType (type)) {
                                        Report.Error (1925, loc, "Cannot initialize object of type `{0}' with a collection initializer",
                                                TypeManager.CSharpName (type));
                                }
                        }

                        eclass = ExprClass.Variable;
                        return this;
                }

                public override void Emit (EmitContext ec)
                {
                        EmitStatement (ec);
                }

                public override void EmitStatement (EmitContext ec)
                {
                        foreach (ExpressionStatement e in initializers)
                                e.EmitStatement (ec);
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        foreach (Expression e in initializers)
                                e.MutateHoistedGenericType (storey);
                }
        }
        
        //
        // New expression with element/object initializers
        //
        public class NewInitialize : New
        {
                //
                // This class serves as a proxy for variable initializer target instances.
                // A real variable is assigned later when we resolve left side of an
                // assignment
                //
                sealed class InitializerTargetExpression : Expression, IMemoryLocation
                {
                        NewInitialize new_instance;

                        public InitializerTargetExpression (NewInitialize newInstance)
                        {
                                this.type = newInstance.type;
                                this.loc = newInstance.loc;
                                this.eclass = newInstance.eclass;
                                this.new_instance = newInstance;
                        }

                        public override Expression CreateExpressionTree (EmitContext ec)
                        {
                                // Should not be reached
                                throw new NotSupportedException ("ET");
                        }

                        public override Expression DoResolve (EmitContext ec)
                        {
                                return this;
                        }

                        public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
                        {
                                return this;
                        }

                        public override void Emit (EmitContext ec)
                        {
                                Expression e = (Expression) new_instance.instance;
                                e.Emit (ec);
                        }

                        #region IMemoryLocation Members

                        public void AddressOf (EmitContext ec, AddressOp mode)
                        {
                                new_instance.instance.AddressOf (ec, mode);
                        }

                        #endregion
                }

                CollectionOrObjectInitializers initializers;
                IMemoryLocation instance;

                public NewInitialize (Expression requested_type, ArrayList arguments, CollectionOrObjectInitializers initializers, Location l)
                        : base (requested_type, arguments, l)
                {
                        this.initializers = initializers;
                }

                protected override IMemoryLocation EmitAddressOf (EmitContext ec, AddressOp Mode)
                {
                        instance = base.EmitAddressOf (ec, Mode);

                        if (!initializers.IsEmpty)
                                initializers.Emit (ec);

                        return instance;
                }

                protected override void CloneTo (CloneContext clonectx, Expression t)
                {
                        base.CloneTo (clonectx, t);

                        NewInitialize target = (NewInitialize) t;
                        target.initializers = (CollectionOrObjectInitializers) initializers.Clone (clonectx);
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        ArrayList args = new ArrayList (2);
                        args.Add (new Argument (base.CreateExpressionTree (ec)));
                        if (!initializers.IsEmpty)
                                args.Add (new Argument (initializers.CreateExpressionTree (ec)));

                        return CreateExpressionFactoryCall (
                                initializers.IsCollectionInitializer ? "ListInit" : "MemberInit",
                                args);
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        if (eclass != ExprClass.Invalid)
                                return this;
                        
                        Expression e = base.DoResolve (ec);
                        if (type == null)
                                return null;

                        Expression previous = ec.CurrentInitializerVariable;
                        ec.CurrentInitializerVariable = new InitializerTargetExpression (this);
                        initializers.Resolve (ec);
                        ec.CurrentInitializerVariable = previous;
                        return e;
                }

                public override bool Emit (EmitContext ec, IMemoryLocation target)
                {
                        bool left_on_stack = base.Emit (ec, target);

                        if (initializers.IsEmpty)
                                return left_on_stack;

                        LocalTemporary temp = target as LocalTemporary;
                        if (temp == null) {
                                if (!left_on_stack) {
                                        VariableReference vr = target as VariableReference;
                                        
                                        // FIXME: This still does not work correctly for pre-set variables
                                        if (vr != null && vr.IsRef)
                                                target.AddressOf (ec, AddressOp.Load);

                                        ((Expression) target).Emit (ec);
                                        left_on_stack = true;
                                }

                                temp = new LocalTemporary (type);
                        }

                        instance = temp;
                        if (left_on_stack)
                                temp.Store (ec);

                        initializers.Emit (ec);

                        if (left_on_stack) {
                                temp.Emit (ec);
                                temp.Release (ec);
                        }

                        return left_on_stack;
                }

                public override bool HasInitializer {
                        get {
                                return !initializers.IsEmpty;
                        }
                }

                public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
                {
                        base.MutateHoistedGenericType (storey);
                        initializers.MutateHoistedGenericType (storey);
                }
        }

        public class AnonymousTypeDeclaration : Expression
        {
                ArrayList parameters;
                readonly TypeContainer parent;
                static readonly ArrayList EmptyParameters = new ArrayList (0);

                public AnonymousTypeDeclaration (ArrayList parameters, TypeContainer parent, Location loc)
                {
                        this.parameters = parameters;
                        this.parent = parent;
                        this.loc = loc;
                }

                protected override void CloneTo (CloneContext clonectx, Expression target)
                {
                        if (parameters == null)
                                return;

                        AnonymousTypeDeclaration t = (AnonymousTypeDeclaration) target;
                        t.parameters = new ArrayList (parameters.Count);
                        foreach (AnonymousTypeParameter atp in parameters)
                                t.parameters.Add (atp.Clone (clonectx));
                }

                AnonymousTypeClass CreateAnonymousType (ArrayList parameters)
                {
                        AnonymousTypeClass type = parent.Module.GetAnonymousType (parameters);
                        if (type != null)
                                return type;

                        type = AnonymousTypeClass.Create (parent, parameters, loc);
                        if (type == null)
                                return null;

                        type.DefineType ();
                        type.Define ();
                        type.EmitType ();
                        if (Report.Errors == 0)
                                type.CloseType ();

                        parent.Module.AddAnonymousType (type);
                        return type;
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        AnonymousTypeClass anonymous_type;

                        if (!ec.IsAnonymousMethodAllowed) {
                                Report.Error (836, loc, "Anonymous types cannot be used in this expression");
                                return null;
                        }

                        if (parameters == null) {
                                anonymous_type = CreateAnonymousType (EmptyParameters);
                                return new New (new TypeExpression (anonymous_type.TypeBuilder, loc),
                                        null, loc).Resolve (ec);
                        }

                        bool error = false;
                        ArrayList arguments = new ArrayList (parameters.Count);
                        TypeExpression [] t_args = new TypeExpression [parameters.Count];
                        for (int i = 0; i < parameters.Count; ++i) {
                                Expression e = ((AnonymousTypeParameter) parameters [i]).Resolve (ec);
                                if (e == null) {
                                        error = true;
                                        continue;
                                }

                                arguments.Add (new Argument (e));
                                t_args [i] = new TypeExpression (e.Type, e.Location);
                        }

                        if (error)
                                return null;

                        anonymous_type = CreateAnonymousType (parameters);
                        if (anonymous_type == null)
                                return null;

                        GenericTypeExpr te = new GenericTypeExpr (anonymous_type.TypeBuilder,
                                new TypeArguments (t_args), loc);

                        return new New (te, arguments, loc).Resolve (ec);
                }

                public override void Emit (EmitContext ec)
                {
                        throw new InternalErrorException ("Should not be reached");
                }
        }

        public class AnonymousTypeParameter : Expression
        {
                public readonly string Name;
                Expression initializer;

                public AnonymousTypeParameter (Expression initializer, string name, Location loc)
                {
                        this.Name = name;
                        this.loc = loc;
                        this.initializer = initializer;
                }
                
                public AnonymousTypeParameter (Parameter parameter)
                {
                        this.Name = parameter.Name;
                        this.loc = parameter.Location;
                        this.initializer = new SimpleName (Name, loc);
                }               

                protected override void CloneTo (CloneContext clonectx, Expression target)
                {
                        AnonymousTypeParameter t = (AnonymousTypeParameter) target;
                        t.initializer = initializer.Clone (clonectx);
                }

                public override Expression CreateExpressionTree (EmitContext ec)
                {
                        throw new NotSupportedException ("ET");
                }

                public override bool Equals (object o)
                {
                        AnonymousTypeParameter other = o as AnonymousTypeParameter;
                        return other != null && Name == other.Name;
                }

                public override int GetHashCode ()
                {
                        return Name.GetHashCode ();
                }

                public override Expression DoResolve (EmitContext ec)
                {
                        Expression e = initializer.Resolve (ec);
                        if (e == null)
                                return null;

                        if (e.eclass == ExprClass.MethodGroup) {
                                Error_InvalidInitializer (e.ExprClassName);
                                return null;
                        }

                        type = e.Type;
                        if (type == TypeManager.void_type || type == TypeManager.null_type ||
                                type == TypeManager.anonymous_method_type || type.IsPointer) {
                                Error_InvalidInitializer (e.GetSignatureForError ());
                                return null;
                        }

                        return e;
                }

                protected virtual void Error_InvalidInitializer (string initializer)
                {
                        Report.Error (828, loc, "An anonymous type property `{0}' cannot be initialized with `{1}'",
                                Name, initializer);
                }

                public override void Emit (EmitContext ec)
                {
                        throw new InternalErrorException ("Should not be reached");
                }
        }
}