//
// expression.cs: Expression representation for the IL tree.
//
// Author:
//   Miguel de Icaza (miguel@ximian.com)
//   Marek Safar (marek.safar@seznam.cz)
//
// (C) 2001, 2002, 2003 Ximian, Inc.
// (C) 2003, 2004 Novell, Inc.
//
#define USE_OLD

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

	/// <summary>
	///   This is just a helper class, it is generated by Unary, UnaryMutator
	///   when an overloaded method has been found.  It just emits the code for a
	///   static call.
	/// </summary>
	public class StaticCallExpr : ExpressionStatement {
		ArrayList args;
		MethodInfo mi;

		public StaticCallExpr (MethodInfo m, ArrayList a, Location l)
		{
			mi = m;
			args = a;

			type = m.ReturnType;
			eclass = ExprClass.Value;
			loc = l;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			//
			// We are born fully resolved
			//
			return this;
		}

		public override void Emit (EmitContext ec)
		{
			if (args != null) 
				Invocation.EmitArguments (ec, mi, args, false, null);

			ec.ig.Emit (OpCodes.Call, mi);
			return;
		}
		
		static public StaticCallExpr MakeSimpleCall (EmitContext ec, MethodGroupExpr mg,
							 Expression e, Location loc)
		{
			ArrayList args;
			MethodBase method;
			
			args = new ArrayList (1);
			Argument a = new Argument (e, Argument.AType.Expression);

                        // We need to resolve the arguments before sending them in !
                        if (!a.Resolve (ec, loc))
                                return null;

                        args.Add (a);
			method = Invocation.OverloadResolve (
				ec, (MethodGroupExpr) mg, args, false, loc);

			if (method == null)
				return null;

			return new StaticCallExpr ((MethodInfo) method, args, loc);
		}

		public override void EmitStatement (EmitContext ec)
		{
			Emit (ec);
			if (TypeManager.TypeToCoreType (type) != TypeManager.void_type)
				ec.ig.Emit (OpCodes.Pop);
		}
		
		public MethodInfo Method {
			get { return mi; }
		}
	}

	public class ParenthesizedExpression : Expression
	{
		public Expression Expr;

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

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

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

		public override Location Location
		{
			get {
				return Expr.Location;
			}
		}
	}
	
	/// <summary>
	///   Unary expressions.  
	/// </summary>
	///
	/// <remarks>
	///   Unary implements unary expressions.   It derives from
	///   ExpressionStatement becuase the pre/post increment/decrement
	///   operators can be used in a statement context.
	/// </remarks>
	public class Unary : Expression {
		public enum Operator : byte {
			UnaryPlus, UnaryNegation, LogicalNot, OnesComplement,
			Indirection, AddressOf,  TOP
		}

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

		/// <summary>
		///   Returns a stringified representation of the Operator
		/// </summary>
		static public 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 "&";
			case Operator.Indirection:
				return "*";
			}

			return oper.ToString ();
		}

		public static readonly string [] oper_names;

		static Unary ()
		{
			oper_names = new string [(int)Operator.TOP];

			oper_names [(int) Operator.UnaryPlus] = "op_UnaryPlus";
			oper_names [(int) Operator.UnaryNegation] = "op_UnaryNegation";
			oper_names [(int) Operator.LogicalNot] = "op_LogicalNot";
			oper_names [(int) Operator.OnesComplement] = "op_OnesComplement";
			oper_names [(int) Operator.Indirection] = "op_Indirection";
			oper_names [(int) Operator.AddressOf] = "op_AddressOf";
		}

		public static void Error_OperatorCannotBeApplied (Location loc, string oper, Type t)
		{
			Error_OperatorCannotBeApplied (loc, oper, TypeManager.CSharpName (t));
		}

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

		void Error23 (Type t)
		{
			Error_OperatorCannotBeApplied (loc, OperName (Oper), t);
		}

		/// <remarks>
		///   The result has been already resolved:
		///
		///   FIXME: a minus constant -128 sbyte cant be turned into a
		///   constant byte.
		/// </remarks>
		static Expression TryReduceNegative (Constant expr)
		{
			Expression e = null;

			if (expr is IntConstant)
				e = new IntConstant (-((IntConstant) expr).Value, expr.Location);
			else if (expr is UIntConstant){
				uint value = ((UIntConstant) expr).Value;

				if (value < 2147483649)
					return new IntConstant (-(int)value, expr.Location);
				else
					e = new LongConstant (-value, expr.Location);
			}
			else if (expr is LongConstant)
				e = new LongConstant (-((LongConstant) expr).Value, expr.Location);
			else if (expr is ULongConstant){
				ulong value = ((ULongConstant) expr).Value;

				if (value < 9223372036854775809)
					return new LongConstant(-(long)value, expr.Location);
			}
			else if (expr is FloatConstant)
				e = new FloatConstant (-((FloatConstant) expr).Value, expr.Location);
			else if (expr is DoubleConstant)
				e = new DoubleConstant (-((DoubleConstant) expr).Value, expr.Location);
			else if (expr is DecimalConstant)
				e = new DecimalConstant (-((DecimalConstant) expr).Value, expr.Location);
			else if (expr is ShortConstant)
				e = new IntConstant (-((ShortConstant) expr).Value, expr.Location);
			else if (expr is UShortConstant)
				e = new IntConstant (-((UShortConstant) expr).Value, expr.Location);
			else if (expr is SByteConstant)
				e = new IntConstant (-((SByteConstant) expr).Value, expr.Location);
			else if (expr is ByteConstant)
				e = new IntConstant (-((ByteConstant) expr).Value, expr.Location);
			return e;
		}

		// <summary>
		//   This routine will attempt to simplify the unary expression when the
		//   argument is a constant.  The result is returned in `result' and the
		//   function returns true or false depending on whether a reduction
		//   was performed or not
		// </summary>
		bool Reduce (EmitContext ec, Constant e, out Expression result)
		{
			Type expr_type = e.Type;
			
			switch (Oper){
			case Operator.UnaryPlus:
				if (expr_type == TypeManager.bool_type){
					result = null;
					Error23 (expr_type);
					return false;
				}
				
				result = e;
				return true;
				
			case Operator.UnaryNegation:
				result = TryReduceNegative (e);
				return result != null;
				
			case Operator.LogicalNot:
				if (expr_type != TypeManager.bool_type) {
					result = null;
					Error23 (expr_type);
					return false;
				}
				
				BoolConstant b = (BoolConstant) e;
				result = new BoolConstant (!(b.Value), b.Location);
				return true;
				
			case Operator.OnesComplement:
				if (!((expr_type == TypeManager.int32_type) ||
				      (expr_type == TypeManager.uint32_type) ||
				      (expr_type == TypeManager.int64_type) ||
				      (expr_type == TypeManager.uint64_type) ||
				      (expr_type.IsSubclassOf (TypeManager.enum_type)))){

					result = null;
					if (Convert.ImplicitConversionExists (ec, e, TypeManager.int32_type)){
						result = new Cast (new TypeExpression (TypeManager.int32_type, loc), e, loc);
						result = result.Resolve (ec);
					} else if (Convert.ImplicitConversionExists (ec, e, TypeManager.uint32_type)){
						result = new Cast (new TypeExpression (TypeManager.uint32_type, loc), e, loc);
						result = result.Resolve (ec);
					} else if (Convert.ImplicitConversionExists (ec, e, TypeManager.int64_type)){
						result = new Cast (new TypeExpression (TypeManager.int64_type, loc), e, loc);
						result = result.Resolve (ec);
					} else if (Convert.ImplicitConversionExists (ec, e, TypeManager.uint64_type)){
						result = new Cast (new TypeExpression (TypeManager.uint64_type, loc), e, loc);
						result = result.Resolve (ec);
					}

					if (result == null || !(result is Constant)){
						result = null;
						Error23 (expr_type);
						return false;
					}

					expr_type = result.Type;
					e = (Constant) result;
				}

				if (e is EnumConstant){
					EnumConstant enum_constant = (EnumConstant) e;
					Expression reduced;
					
					if (Reduce (ec, enum_constant.Child, out reduced)){
						result = new EnumConstant ((Constant) reduced, enum_constant.Type);
						return true;
					} else {
						result = null;
						return false;
					}
				}

				if (expr_type == TypeManager.int32_type){
					result = new IntConstant (~ ((IntConstant) e).Value, e.Location);
				} else if (expr_type == TypeManager.uint32_type){
					result = new UIntConstant (~ ((UIntConstant) e).Value, e.Location);
				} else if (expr_type == TypeManager.int64_type){
					result = new LongConstant (~ ((LongConstant) e).Value, e.Location);
				} else if (expr_type == TypeManager.uint64_type){
					result = new ULongConstant (~ ((ULongConstant) e).Value, e.Location);
				} else {
					result = null;
					Error23 (expr_type);
					return false;
				}
				return true;

			case Operator.AddressOf:
				result = this;
				return false;

			case Operator.Indirection:
				result = this;
				return false;
			}
			throw new Exception ("Can not constant fold: " + Oper.ToString());
		}

		Expression ResolveOperator (EmitContext ec)
		{
			//
			// Step 1: Default operations on CLI native types.
			//

			// Attempt to use a constant folding operation.
			if (Expr is Constant){
				Expression result;
				
				if (Reduce (ec, (Constant) Expr, out result))
					return result;
			}

			//
			// Step 2: Perform Operator Overload location
			//
			Type expr_type = Expr.Type;
			Expression mg;
			string op_name;
			
			op_name = oper_names [(int) Oper];

			mg = MemberLookup (ec.ContainerType, expr_type, op_name, MemberTypes.Method, AllBindingFlags, loc);
			
			if (mg != null) {
				Expression e = StaticCallExpr.MakeSimpleCall (
					ec, (MethodGroupExpr) mg, Expr, loc);

				if (e == null){
					Error23 (expr_type);
					return null;
				}
				
				return e;
			}

			// Only perform numeric promotions on:
			// +, - 

			if (expr_type == null)
				return null;
			
			switch (Oper){
			case Operator.LogicalNot:
				if (expr_type != TypeManager.bool_type) {
					Expr = ResolveBoolean (ec, Expr, loc);
					if (Expr == null){
						Error23 (expr_type);
						return null;
					}
				}
				
				type = TypeManager.bool_type;
				return this;

			case Operator.OnesComplement:
				if (!((expr_type == TypeManager.int32_type) ||
				      (expr_type == TypeManager.uint32_type) ||
				      (expr_type == TypeManager.int64_type) ||
				      (expr_type == TypeManager.uint64_type) ||
				      (expr_type.IsSubclassOf (TypeManager.enum_type)))){
					Expression e;

					e = Convert.ImplicitConversion (ec, Expr, TypeManager.int32_type, loc);
					if (e != null)
						goto ok;
					e = Convert.ImplicitConversion (ec, Expr, TypeManager.uint32_type, loc);
					if (e != null)
						goto ok;
					e = Convert.ImplicitConversion (ec, Expr, TypeManager.int64_type, loc);
					if (e != null)
						goto ok;
					e = Convert.ImplicitConversion (ec, Expr, TypeManager.uint64_type, loc);
					if (e != null)
						goto ok;
					Error23 (expr_type);
					return null;
				ok:
					Expr = e;
					expr_type = e.Type;
				}

				type = expr_type;
				return this;

			case Operator.AddressOf:
				if (!ec.InUnsafe) {
					UnsafeError (loc); 
					return null;
				}
				
				if (!TypeManager.VerifyUnManaged (Expr.Type, loc)){
					return null;
				}

				IVariable variable = Expr as IVariable;
				bool is_fixed = variable != null && variable.VerifyFixed ();

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

				if (ec.InFixedInitializer && is_fixed) {
					Error (213, "You cannot use the fixed statement to take the address of an already fixed expression");
					return null;
				}

				LocalVariableReference lr = Expr as LocalVariableReference;
				if (lr != null){
					if (lr.local_info.IsCaptured){
						AnonymousMethod.Error_AddressOfCapturedVar (lr.Name, loc);
						return null;
					}
					lr.local_info.AddressTaken = true;
					lr.local_info.Used = true;
				}

				ParameterReference pr = Expr as ParameterReference;
				if ((pr != null) && pr.Parameter.IsCaptured) {
					AnonymousMethod.Error_AddressOfCapturedVar (pr.Name, loc);
					return null;
				}

				// According to the specs, a variable is considered definitely assigned if you take
				// its address.
				if ((variable != null) && (variable.VariableInfo != null)){
					variable.VariableInfo.SetAssigned (ec);
				}

				type = TypeManager.GetPointerType (Expr.Type);
				return this;

			case Operator.Indirection:
				if (!ec.InUnsafe){
					UnsafeError (loc);
					return null;
				}
				
				if (!expr_type.IsPointer){
					Error (193, "The * or -> operator must be applied to a pointer");
					return null;
				}
				
				//
				// We create an Indirection expression, because
				// it can implement the IMemoryLocation.
				// 
				return new Indirection (Expr, loc);
			
			case Operator.UnaryPlus:
				//
				// A plus in front of something is just a no-op, so return the child.
				//
				return Expr;

			case Operator.UnaryNegation:
				//
				// Deals with -literals
				// int     operator- (int x)
				// long    operator- (long x)
				// float   operator- (float f)
				// double  operator- (double d)
				// decimal operator- (decimal d)
				//
				Expression expr = null;

				//
				// transform - - expr into expr
				//
				if (Expr is Unary){
					Unary unary = (Unary) Expr;
					
					if (unary.Oper == Operator.UnaryNegation)
						return unary.Expr;
				}

				//
				// perform numeric promotions to int,
				// long, double.
				//
				//
				// The following is inneficient, because we call
				// ImplicitConversion too many times.
				//
				// It is also not clear if we should convert to Float
				// or Double initially.
				//
				if (expr_type == TypeManager.uint32_type){
					//
					// FIXME: handle exception to this rule that
					// permits the int value -2147483648 (-2^31) to
					// bt wrote as a decimal interger literal
					//
					type = TypeManager.int64_type;
					Expr = Convert.ImplicitConversion (ec, Expr, type, loc);
					return this;
				}

				if (expr_type == TypeManager.uint64_type){
					//
					// FIXME: Handle exception of `long value'
					// -92233720368547758087 (-2^63) to be wrote as
					// decimal integer literal.
					//
					Error23 (expr_type);
					return null;
				}

				if (expr_type == TypeManager.float_type){
					type = expr_type;
					return this;
				}
				
				expr = Convert.ImplicitConversion (ec, Expr, TypeManager.int32_type, loc);
				if (expr != null){
					Expr = expr;
					type = expr.Type;
					return this;
				} 

				expr = Convert.ImplicitConversion (ec, Expr, TypeManager.int64_type, loc);
				if (expr != null){
					Expr = expr;
					type = expr.Type;
					return this;
				}

				expr = Convert.ImplicitConversion (ec, Expr, TypeManager.double_type, loc);
				if (expr != null){
					Expr = expr;
					type = expr.Type;
					return this;
				}
				
				Error23 (expr_type);
				return null;
			}

			Error (187, "No such operator '" + OperName (Oper) + "' defined for type '" +
			       TypeManager.CSharpName (expr_type) + "'");
			return null;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			if (Oper == Operator.AddressOf) {
				Expr = Expr.DoResolveLValue (ec, new EmptyExpression ());

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

#if GMCS_SOURCE
			if (TypeManager.IsNullableValueType (Expr.Type))
				return new Nullable.LiftedUnaryOperator (Oper, Expr, loc).Resolve (ec);
#endif

			eclass = ExprClass.Value;
			return ResolveOperator (ec);
		}

		public override Expression DoResolveLValue (EmitContext ec, Expression right)
		{
			if (Oper == Operator.Indirection)
				return DoResolve (ec);

			return null;
		}

		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			switch (Oper) {
			case Operator.UnaryPlus:
				throw new Exception ("This should be caught by Resolve");
				
			case Operator.UnaryNegation:
				if (ec.CheckState && type != TypeManager.float_type && type != TypeManager.double_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 ());
			}
		}

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

		public override string ToString ()
		{
			return "Unary (" + Oper + ", " + Expr + ")";
		}
		
	}

	//
	// 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, IVariable {
		Expression expr;
		LocalTemporary temporary;
		bool prepared;
		
		public Indirection (Expression expr, Location l)
		{
			this.expr = expr;
			type = TypeManager.HasElementType (expr.Type) ? TypeManager.GetElementType (expr.Type) : expr.Type;
			eclass = ExprClass.Variable;
			loc = l;
		}
		
		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)
		{
			//
			// Born fully resolved
			//
			return this;
		}
		
		public override string ToString ()
		{
			return "*(" + expr + ")";
		}

		#region IVariable Members

		public VariableInfo VariableInfo {
			get { return null; }
		}

		public bool VerifyFixed ()
		{
			// A pointer-indirection is always fixed.
			return true;
		}

		#endregion
	}
	
	/// <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.
		//
		StaticCallExpr method;

		public UnaryMutator (Mode m, Expression e, Location l)
		{
			mode = m;
			loc = l;
			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) ||
				(t.IsSubclassOf (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 = expr.Type;

			//
			// Step 1: Perform Operator Overload location
			//
			Expression mg;
			string op_name;
			
			if (mode == Mode.PreIncrement || mode == Mode.PostIncrement)
				op_name = "op_Increment";
			else 
				op_name = "op_Decrement";

			mg = MemberLookup (ec.ContainerType, expr_type, op_name, MemberTypes.Method, AllBindingFlags, loc);

			if (mg != null) {
				method = StaticCallExpr.MakeSimpleCall (
					ec, (MethodGroupExpr) mg, expr, loc);

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

			//
			// 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
			//
			type = expr_type;
			if (expr.eclass == ExprClass.Variable){
				LocalVariableReference var = expr as LocalVariableReference;
				if ((var != null) && var.IsReadOnly) {
					Error (1604, "cannot assign to `" + var.Name + "' because it is readonly");
					return null;
				}
			} else if (expr.eclass == ExprClass.IndexerAccess || expr.eclass == ExprClass.PropertyAccess){
				expr = expr.ResolveLValue (ec, this, Location);
				if (expr == null)
					return null;
			} else {
				if (expr.eclass == ExprClass.Value) {
					Error_ValueAssignment (loc);
				} else {
					expr.Error_UnexpectedKind (ec.DeclContainer, "variable, indexer or property access", loc);
				}
				return null;
			}

			return this;
		}

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

			eclass = ExprClass.Value;

#if GMCS_SOURCE
			if (TypeManager.IsNullableValueType (expr.Type))
				return new Nullable.LiftedUnaryMutator (mode, expr, loc).Resolve (ec);
#endif

			return ResolveOperator (ec);
		}

		static int PtrTypeSize (Type t)
		{
			return GetTypeSize (TypeManager.GetElementType (t));
		}

		//
		// 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){
				int n = PtrTypeSize (t);
				
				if (n == 0)
					ig.Emit (OpCodes.Sizeof, t);
				else
					IntConstant.EmitInt (ig, n);
			} else 
				ig.Emit (OpCodes.Ldc_I4_1);

			//
			// Now emit the operation
			//
			if (ec.CheckState){
				if (t == TypeManager.int32_type ||
				    t == TypeManager.int64_type){
					if ((mode & Mode.IsDecrement) != 0)
						ig.Emit (OpCodes.Sub_Ovf);
					else
						ig.Emit (OpCodes.Add_Ovf);
				} else if (t == TypeManager.uint32_type ||
					   t == TypeManager.uint64_type){
					if ((mode & Mode.IsDecrement) != 0)
						ig.Emit (OpCodes.Sub_Ovf_Un);
					else
						ig.Emit (OpCodes.Add_Ovf_Un);
				} else {
					if ((mode & Mode.IsDecrement) != 0)
						ig.Emit (OpCodes.Sub_Ovf);
					else
						ig.Emit (OpCodes.Add_Ovf);
				}
			} else {
				if ((mode & Mode.IsDecrement) != 0)
					ig.Emit (OpCodes.Sub);
				else
					ig.Emit (OpCodes.Add);
			}

			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, method.Method);
				recurse = false;
				return;
			}

			EmitCode (ec, true);
		}

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

	/// <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 (expr.Type.IsPointer) {
				Report.Error (244, loc, "\"is\" or \"as\" are not valid on pointer types");
				return null;
			}
			return this;
		}
	}

	/// <summary>
	///   Implementation of the `is' operator.
	/// </summary>
	public class Is : Probe {
		public Is (Expression expr, Expression probe_type, Location l)
			: base (expr, probe_type, l)
		{
		}

		enum Action {
			AlwaysTrue, AlwaysNull, AlwaysFalse, LeaveOnStack, Probe
		}

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

			expr.Emit (ec);

			switch (action){
			case Action.AlwaysFalse:
				ig.Emit (OpCodes.Pop);
				IntConstant.EmitInt (ig, 0);
				return;
			case Action.AlwaysTrue:
				ig.Emit (OpCodes.Pop);
				IntConstant.EmitInt (ig, 1);
				return;
			case Action.LeaveOnStack:
				// the `e != null' rule.
				ig.Emit (OpCodes.Ldnull);
				ig.Emit (OpCodes.Ceq);
				ig.Emit (OpCodes.Ldc_I4_0);
				ig.Emit (OpCodes.Ceq);
				return;
			case Action.Probe:
				ig.Emit (OpCodes.Isinst, probe_type_expr.Type);
				ig.Emit (OpCodes.Ldnull);
				ig.Emit (OpCodes.Cgt_Un);
				return;
			}
			throw new Exception ("never reached");
		}

		public override void EmitBranchable (EmitContext ec, Label target, bool onTrue)
		{
			ILGenerator ig = ec.ig;

			switch (action){
			case Action.AlwaysFalse:
				if (! onTrue)
					ig.Emit (OpCodes.Br, target);
				
				return;
			case Action.AlwaysTrue:
				if (onTrue)
					ig.Emit (OpCodes.Br, target);
				
				return;
			case Action.LeaveOnStack:
				// the `e != null' rule.
				expr.Emit (ec);
				ig.Emit (onTrue ? OpCodes.Brtrue : OpCodes.Brfalse, target);
				return;
			case Action.Probe:
				expr.Emit (ec);
				ig.Emit (OpCodes.Isinst, probe_type_expr.Type);
				ig.Emit (onTrue ? OpCodes.Brtrue : OpCodes.Brfalse, target);
				return;
			}
			throw new Exception ("never reached");
		}

		public override Expression DoResolve (EmitContext ec)
		{
			Expression e = base.DoResolve (ec);

			if ((e == null) || (expr == null))
				return null;

			Type etype = expr.Type;
			type = TypeManager.bool_type;
			eclass = ExprClass.Value;

			//
			// First case, if at compile time, there is an implicit conversion
			// then e != null (objects) or true (value types)
			//
			Type probe_type = probe_type_expr.Type;
			e = Convert.ImplicitConversionStandard (ec, expr, probe_type, loc);
			if (e != null){
				expr = e;
				if (etype.IsValueType)
					action = Action.AlwaysTrue;
				else
					action = Action.LeaveOnStack;

				Constant c = e as Constant;
				if (c != null && c.GetValue () == null) {
					action = Action.AlwaysFalse;
					Report.Warning (184, 1, loc, "The given expression is never of the provided (`{0}') type",
						TypeManager.CSharpName (probe_type));
				} else {
					Report.Warning (183, 1, loc, "The given expression is always of the provided (`{0}') type",
						TypeManager.CSharpName (probe_type));
				}
				return this;
			}
			
			if (Convert.ExplicitReferenceConversionExists (etype, probe_type)){
				if (TypeManager.IsGenericParameter (etype))
					expr = new BoxedCast (expr, etype);

				//
				// Second case: explicit reference convresion
				//
				if (expr is NullLiteral)
					action = Action.AlwaysFalse;
				else
					action = Action.Probe;
			} else if (TypeManager.ContainsGenericParameters (etype) ||
				   TypeManager.ContainsGenericParameters (probe_type)) {
				expr = new BoxedCast (expr, etype);
				action = Action.Probe;
			} else {
				action = Action.AlwaysFalse;
				if (!(probe_type.IsInterface || expr.Type.IsInterface))
					Report.Warning (184, 1, loc, "The given expression is never of the provided (`{0}') type", TypeManager.CSharpName (probe_type));
			}

			return this;
		}
	}

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

		bool do_isinst = false;
		Expression resolved_type;
		
		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;

			expr.Emit (ec);

			if (do_isinst)
				ig.Emit (OpCodes.Isinst, probe_type_expr.Type);
		}

		static void Error_CannotConvertType (Type source, Type target, Location loc)
		{
			Report.Error (39, loc, "Cannot convert type `{0}' to `{1}' via a built-in conversion",
				TypeManager.CSharpName (source),
				TypeManager.CSharpName (target));
		}
		
		public override Expression DoResolve (EmitContext ec)
		{
			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 (type.IsValueType) {
				Report.Error (77, loc, "The as operator must be used with a reference type (`" +
					      TypeManager.CSharpName (type) + "' is a value type)");
				return null;
			
			}

#if GMCS_SOURCE
			//
			// If the type is a type parameter, ensure
			// that it is constrained by a class
			//
			TypeParameterExpr tpe = probe_type_expr as TypeParameterExpr;
			if (tpe != null){
				Constraints constraints = tpe.TypeParameter.Constraints;
				bool error = false;
				
				if (constraints == null)
					error = true;
				else {
					if (!constraints.HasClassConstraint)
						if ((constraints.Attributes & GenericParameterAttributes.ReferenceTypeConstraint) == 0)
							error = true;
				}
				if (error){
					Report.Error (413, loc,
						      "The as operator requires that the `{0}' type parameter be constrained by a class",
						      probe_type_expr.GetSignatureForError ());
					return null;
				}
			}
#endif
			
			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;
			}

			Error_CannotConvertType (etype, type, loc);
			return null;
		}
	
		public override bool GetAttributableValue (Type valueType, out object value)
		{
			return expr.GetAttributableValue (valueType, 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;

			if (target_type == TypeManager.system_void_expr)
				Error_VoidInvalidInTheContext (loc);
		}

		public Expression TargetType {
			get { return target_type; }
		}

		public Expression Expr {
			get { return expr; }
			set { expr = value; }
		}

		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) {
				try {
					c = c.TryReduce (ec, type, loc);
					if (c != null)
						return c;
				}
				catch (OverflowException) {
					return null;
				}
			}

			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");
		}
	}

	/// <summary>
	///   Binary operators
	/// </summary>
	public class Binary : Expression {
		public enum Operator : byte {
			Multiply, Division, Modulus,
			Addition, Subtraction,
			LeftShift, RightShift,
			LessThan, GreaterThan, LessThanOrEqual, GreaterThanOrEqual, 
			Equality, Inequality,
			BitwiseAnd,
			ExclusiveOr,
			BitwiseOr,
			LogicalAnd,
			LogicalOr,
			TOP
		}

		Operator oper;
		Expression left, right;

		// This must be kept in sync with Operator!!!
		public static readonly string [] oper_names;
		
		static Binary ()
		{
			oper_names = new string [(int) Operator.TOP];

			oper_names [(int) Operator.Multiply] = "op_Multiply";
			oper_names [(int) Operator.Division] = "op_Division";
			oper_names [(int) Operator.Modulus] = "op_Modulus";
			oper_names [(int) Operator.Addition] = "op_Addition";
			oper_names [(int) Operator.Subtraction] = "op_Subtraction";
			oper_names [(int) Operator.LeftShift] = "op_LeftShift";
			oper_names [(int) Operator.RightShift] = "op_RightShift";
			oper_names [(int) Operator.LessThan] = "op_LessThan";
			oper_names [(int) Operator.GreaterThan] = "op_GreaterThan";
			oper_names [(int) Operator.LessThanOrEqual] = "op_LessThanOrEqual";
			oper_names [(int) Operator.GreaterThanOrEqual] = "op_GreaterThanOrEqual";
			oper_names [(int) Operator.Equality] = "op_Equality";
			oper_names [(int) Operator.Inequality] = "op_Inequality";
			oper_names [(int) Operator.BitwiseAnd] = "op_BitwiseAnd";
			oper_names [(int) Operator.BitwiseOr] = "op_BitwiseOr";
			oper_names [(int) Operator.ExclusiveOr] = "op_ExclusiveOr";
			oper_names [(int) Operator.LogicalOr] = "op_LogicalOr";
			oper_names [(int) Operator.LogicalAnd] = "op_LogicalAnd";
		}

		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;
			}
			set {
				oper = value;
			}
		}
		
		public Expression Left {
			get {
				return left;
			}
			set {
				left = value;
			}
		}

		public Expression Right {
			get {
				return right;
			}
			set {
				right = value;
			}
		}


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

			return oper.ToString ();
		}

		public override string ToString ()
		{
			return "operator " + OperName (oper) + "(" + left.ToString () + ", " +
				right.ToString () + ")";
		}
		
		Expression ForceConversion (EmitContext ec, Expression expr, Type target_type)
		{
			if (expr.Type == target_type)
				return expr;

			return Convert.ImplicitConversion (ec, expr, target_type, loc);
		}

		public static void Error_OperatorAmbiguous (Location loc, Operator oper, Type l, Type r)
		{
			Report.Error (
				34, loc, "Operator `" + OperName (oper) 
				+ "' is ambiguous on operands of type `"
				+ TypeManager.CSharpName (l) + "' "
				+ "and `" + TypeManager.CSharpName (r)
				+ "'");
		}

		bool IsConvertible (EmitContext ec, Expression le, Expression re, Type t)
		{
			return Convert.ImplicitConversionExists (ec, le, t) && Convert.ImplicitConversionExists (ec, re, t);
		}

		bool VerifyApplicable_Predefined (EmitContext ec, Type t)
		{
			if (!IsConvertible (ec, left, right, t))
				return false;
			left = ForceConversion (ec, left, t);
			right = ForceConversion (ec, right, t);
			type = t;
			return true;
		}

		bool IsApplicable_String (EmitContext ec, Expression le, Expression re, Operator oper)
		{
			bool l = Convert.ImplicitConversionExists (ec, le, TypeManager.string_type);
			bool r = Convert.ImplicitConversionExists (ec, re, TypeManager.string_type);

			if (oper == Operator.Equality || oper == Operator.Inequality)
				return l && r;
			if (oper == Operator.Addition)
				return l || r;
			return false;
		}

		bool OverloadResolve_PredefinedString (EmitContext ec, Operator oper)
		{
			if (!IsApplicable_String (ec, left, right, oper))
				return false;
			Type t = TypeManager.string_type;
			if (Convert.ImplicitConversionExists (ec, left, t))
				left = ForceConversion (ec, left, t);
			if (Convert.ImplicitConversionExists (ec, right, t))
				right = ForceConversion (ec, right, t);
			type = t;
			return true;
		}

		bool OverloadResolve_PredefinedIntegral (EmitContext ec)
		{
			return VerifyApplicable_Predefined (ec, TypeManager.int32_type) ||
				VerifyApplicable_Predefined (ec, TypeManager.uint32_type) ||
				VerifyApplicable_Predefined (ec, TypeManager.int64_type) ||
				VerifyApplicable_Predefined (ec, TypeManager.uint64_type) ||
				false;
		}

		bool OverloadResolve_PredefinedFloating (EmitContext ec)
		{
			return VerifyApplicable_Predefined (ec, TypeManager.float_type) ||
				VerifyApplicable_Predefined (ec, TypeManager.double_type) ||
				false;
		}

		static public void Error_OperatorCannotBeApplied (Location loc, string name, Type l, Type r)
		{
			Error_OperatorCannotBeApplied (loc, name, TypeManager.CSharpName (l), TypeManager.CSharpName (r));
		}

		public static void Error_OperatorCannotBeApplied (Location loc, string name, string left, string right)
		{
			Report.Error (19, loc, "Operator `{0}' cannot be applied to operands of type `{1}' and `{2}'",
				name, left, right);
		}
		
		void Error_OperatorCannotBeApplied ()
		{
			Error_OperatorCannotBeApplied (Location, OperName (oper), TypeManager.CSharpName (left.Type),
				TypeManager.CSharpName(right.Type));
		}

		static bool is_unsigned (Type t)
		{
			return (t == TypeManager.uint32_type || t == TypeManager.uint64_type ||
				t == TypeManager.short_type || t == TypeManager.byte_type);
		}

		Expression Make32or64 (EmitContext ec, Expression e)
		{
			Type t= e.Type;
			
			if (t == TypeManager.int32_type || t == TypeManager.uint32_type ||
			    t == TypeManager.int64_type || t == TypeManager.uint64_type)
				return e;
			Expression ee = Convert.ImplicitConversion (ec, e, TypeManager.int32_type, loc);
			if (ee != null)
				return ee;
			ee = Convert.ImplicitConversion (ec, e, TypeManager.uint32_type, loc);
			if (ee != null)
				return ee;
			ee = Convert.ImplicitConversion (ec, e, TypeManager.int64_type, loc);
			if (ee != null)
				return ee;
			ee = Convert.ImplicitConversion (ec, e, TypeManager.uint64_type, loc);
			if (ee != null)
				return ee;
			return null;
		}
					
		Expression CheckShiftArguments (EmitContext ec)
		{
			Expression new_left = Make32or64 (ec, left);
			Expression new_right = ForceConversion (ec, right, TypeManager.int32_type);
			if (new_left == null || new_right == null) {
				Error_OperatorCannotBeApplied ();
				return null;
			}
			type = new_left.Type;
			int shiftmask = (type == TypeManager.int32_type || type == TypeManager.uint32_type) ? 31 : 63;
			left = new_left;
			right = new Binary (Binary.Operator.BitwiseAnd, new_right, new IntConstant (shiftmask, loc)).DoResolve (ec);
			return this;
		}

		//
		// This is used to check if a test 'x == null' can be optimized to a reference equals,
		// i.e., not invoke op_Equality.
		//
		static bool EqualsNullIsReferenceEquals (Type t)
		{
			return t == TypeManager.object_type || t == TypeManager.string_type ||
				t == TypeManager.delegate_type || t.IsSubclassOf (TypeManager.delegate_type);
		}

		static void Warning_UnintendedReferenceComparison (Location loc, string side, Type type)
		{
			Report.Warning ((side == "left" ? 252 : 253), 2, loc,
				"Possible unintended reference comparison; to get a value comparison, " +
				"cast the {0} hand side to type `{1}'.", side, TypeManager.CSharpName (type));
		}

		Expression ResolveOperator (EmitContext ec)
		{
			Type l = left.Type;
			Type r = right.Type;

			if (oper == Operator.Equality || oper == Operator.Inequality){
				if (TypeManager.IsGenericParameter (l) && (right is NullLiteral)) {
					if (l.BaseType == TypeManager.value_type) {
						Error_OperatorCannotBeApplied ();
						return null;
					}

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

				if (TypeManager.IsGenericParameter (r) && (left is NullLiteral)) {
					if (r.BaseType == TypeManager.value_type) {
						Error_OperatorCannotBeApplied ();
						return null;
					}

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

				//
				// Optimize out call to op_Equality in a few cases.
				//
				if ((l == TypeManager.null_type && EqualsNullIsReferenceEquals (r)) ||
				    (r == TypeManager.null_type && EqualsNullIsReferenceEquals (l))) {
					Type = TypeManager.bool_type;
					return this;
				}

				// IntPtr equality
				if (l == TypeManager.intptr_type && r == TypeManager.intptr_type) {
					Type = TypeManager.bool_type;
					return this;
				}
			}

			//
			// Do not perform operator overload resolution when both sides are
			// built-in types
			//
			Expression left_operators = null, right_operators = null;
			if (!(TypeManager.IsPrimitiveType (l) && TypeManager.IsPrimitiveType (r))) {
				//
				// Step 1: Perform Operator Overload location
				//
				string op = oper_names [(int) oper];

				MethodGroupExpr union;
				left_operators = MemberLookup (ec.ContainerType, l, op, MemberTypes.Method, AllBindingFlags, loc);
				if (r != l){
					right_operators = MemberLookup (
						ec.ContainerType, r, op, MemberTypes.Method, AllBindingFlags, loc);
					union = Invocation.MakeUnionSet (left_operators, right_operators, loc);
				} else
					union = (MethodGroupExpr) left_operators;

				if (union != null) {
					ArrayList args = new ArrayList (2);
					args.Add (new Argument (left, Argument.AType.Expression));
					args.Add (new Argument (right, Argument.AType.Expression));

					MethodBase method = Invocation.OverloadResolve (ec, union, args, true, Location.Null);

					if (method != null) {
						MethodInfo mi = (MethodInfo) method;
						return new BinaryMethod (mi.ReturnType, method, args);
					}
				}
			}

			//
			// Step 0: String concatenation (because overloading will get this wrong)
			//
			if (oper == Operator.Addition){
				//
				// If any of the arguments is a string, cast to string
				//
				
				// Simple constant folding
				if (left is StringConstant && right is StringConstant)
					return new StringConstant (((StringConstant) left).Value + ((StringConstant) right).Value, left.Location);
				
				if (l == TypeManager.string_type || r == TypeManager.string_type) {

					if (r == TypeManager.void_type || l == TypeManager.void_type) {
						Error_OperatorCannotBeApplied ();
						return null;
					}

					// try to fold it in on the left
					if (left is StringConcat) {

						//
						// We have to test here for not-null, since we can be doubly-resolved
						// take care of not appending twice
						//
						if (type == null){
							type = TypeManager.string_type;
							((StringConcat) left).Append (ec, right);
							return left.Resolve (ec);
						} else {
							return left;
						}
					}

					// Otherwise, start a new concat expression
					return new StringConcat (ec, loc, left, right).Resolve (ec);
				}

				//
				// Transform a + ( - b) into a - b
				//
				if (right is Unary){
					Unary right_unary = (Unary) right;

					if (right_unary.Oper == Unary.Operator.UnaryNegation){
						oper = Operator.Subtraction;
						right = right_unary.Expr;
						r = right.Type;
					}
				}
			}

			if (oper == Operator.Equality || oper == Operator.Inequality){
				if (l == TypeManager.bool_type || r == TypeManager.bool_type){
					if (r != TypeManager.bool_type || l != TypeManager.bool_type){
						Error_OperatorCannotBeApplied ();
						return null;
					}

					type = TypeManager.bool_type;
					return this;
				}

				if (l.IsPointer || r.IsPointer) {
					if (l.IsPointer && r.IsPointer) {
						type = TypeManager.bool_type;
						return this;
					}

					if (l.IsPointer && r == TypeManager.null_type) {
						right = new EmptyCast (NullPointer.Null, l);
						type = TypeManager.bool_type;
						return this;
					}

					if (r.IsPointer && l == TypeManager.null_type) {
						left = new EmptyCast (NullPointer.Null, r);
						type = TypeManager.bool_type;
						return this;
					}
				}

#if GMCS_SOURCE
				if (l.IsGenericParameter && r.IsGenericParameter) {
					GenericConstraints l_gc, r_gc;

					l_gc = TypeManager.GetTypeParameterConstraints (l);
					r_gc = TypeManager.GetTypeParameterConstraints (r);

					if ((l_gc == null) || (r_gc == null) ||
					    !(l_gc.HasReferenceTypeConstraint || l_gc.HasClassConstraint) ||
					    !(r_gc.HasReferenceTypeConstraint || r_gc.HasClassConstraint)) {
						Error_OperatorCannotBeApplied ();
						return null;
					}

				}
#endif

				//
				// operator != (object a, object b)
				// operator == (object a, object b)
				//
				// For this to be used, both arguments have to be reference-types.
				// Read the rationale on the spec (14.9.6)
				//
				if (!(l.IsValueType || r.IsValueType)){
					type = TypeManager.bool_type;

					if (l == r)
						return this;
					
					//
					// Also, a standard conversion must exist from either one
					//
					bool left_to_right =
						Convert.ImplicitStandardConversionExists (left, r);
					bool right_to_left = !left_to_right &&
						Convert.ImplicitStandardConversionExists (right, l);

					if (!left_to_right && !right_to_left) {
						Error_OperatorCannotBeApplied ();
						return null;
					}

					if (left_to_right && left_operators != null &&
					    RootContext.WarningLevel >= 2) {
						ArrayList args = new ArrayList (2);
						args.Add (new Argument (left, Argument.AType.Expression));
						args.Add (new Argument (left, Argument.AType.Expression));
						MethodBase method = Invocation.OverloadResolve (
							ec, (MethodGroupExpr) left_operators, args, true, Location.Null);
						if (method != null)
							Warning_UnintendedReferenceComparison (loc, "right", l);
					}

					if (right_to_left && right_operators != null &&
					    RootContext.WarningLevel >= 2) {
						ArrayList args = new ArrayList (2);
						args.Add (new Argument (right, Argument.AType.Expression));
						args.Add (new Argument (right, Argument.AType.Expression));
						MethodBase method = Invocation.OverloadResolve (
							ec, (MethodGroupExpr) right_operators, args, true, Location.Null);
						if (method != null)
							Warning_UnintendedReferenceComparison (loc, "left", r);
					}

					//
					// We are going to have to convert to an object to compare
					//
					if (l != TypeManager.object_type)
						left = new EmptyCast (left, TypeManager.object_type);
					if (r != TypeManager.object_type)
						right = new EmptyCast (right, TypeManager.object_type);

					return this;
				}
			}

			// Only perform numeric promotions on:
			// +, -, *, /, %, &, |, ^, ==, !=, <, >, <=, >=
			//
			if (oper == Operator.Addition || oper == Operator.Subtraction) {
				if (TypeManager.IsDelegateType (l)){
					if (((right.eclass == ExprClass.MethodGroup) ||
					     (r == TypeManager.anonymous_method_type))){
						if ((RootContext.Version != LanguageVersion.ISO_1)){
							Expression tmp = Convert.ImplicitConversionRequired (ec, right, l, loc);
							if (tmp == null)
								return null;
							right = tmp;
							r = right.Type;
						}
					}

					if (TypeManager.IsDelegateType (r) || right is NullLiteral){
						MethodInfo method;
						ArrayList args = new ArrayList (2);
					
						args = new ArrayList (2);
						args.Add (new Argument (left, Argument.AType.Expression));
						args.Add (new Argument (right, Argument.AType.Expression));
					
						if (oper == Operator.Addition)
							method = TypeManager.delegate_combine_delegate_delegate;
						else
							method = TypeManager.delegate_remove_delegate_delegate;

						if (!TypeManager.IsEqual (l, r) && !(right is NullLiteral)) {
							Error_OperatorCannotBeApplied ();
							return null;
						}

						return new BinaryDelegate (l, method, args);
					}
				}

				//
				// Pointer arithmetic:
				//
				// T* operator + (T* x, int y);
				// T* operator + (T* x, uint y);
				// T* operator + (T* x, long y);
				// T* operator + (T* x, ulong y);
				//
				// T* operator + (int y,   T* x);
				// T* operator + (uint y,  T *x);
				// T* operator + (long y,  T *x);
				// T* operator + (ulong y, T *x);
				//
				// T* operator - (T* x, int y);
				// T* operator - (T* x, uint y);
				// T* operator - (T* x, long y);
				// T* operator - (T* x, ulong y);
				//
				// long operator - (T* x, T *y)
				//
				if (l.IsPointer){
					if (r.IsPointer && oper == Operator.Subtraction){
						if (r == l)
							return new PointerArithmetic (
								false, left, right, TypeManager.int64_type,
								loc).Resolve (ec);
					} else {
						Expression t = Make32or64 (ec, right);
						if (t != null)
							return new PointerArithmetic (oper == Operator.Addition, left, t, l, loc).Resolve (ec);
					}
				} else if (r.IsPointer && oper == Operator.Addition){
					Expression t = Make32or64 (ec, left);
					if (t != null)
						return new PointerArithmetic (true, right, t, r, loc).Resolve (ec);
				}
			}
			
			//
			// Enumeration operators
			//
			bool lie = TypeManager.IsEnumType (l);
			bool rie = TypeManager.IsEnumType (r);
			if (lie || rie){
				Expression temp;

				// U operator - (E e, E f)
				if (lie && rie){
					if (oper == Operator.Subtraction){
						if (l == r){
							type = TypeManager.EnumToUnderlying (l);
							return this;
						}
						Error_OperatorCannotBeApplied ();
						return null;
					}
				}
					
				//
				// operator + (E e, U x)
				// operator - (E e, U x)
				//
				if (oper == Operator.Addition || oper == Operator.Subtraction){
					Type enum_type = lie ? l : r;
					Type other_type = lie ? r : l;
					Type underlying_type = TypeManager.EnumToUnderlying (enum_type);
					
					if (underlying_type != other_type){
						temp = Convert.ImplicitConversion (ec, lie ? right : left, underlying_type, loc);
						if (temp != null){
							if (lie)
								right = temp;
							else
								left = temp;
							type = enum_type;
							return this;
						}
							
						Error_OperatorCannotBeApplied ();
						return null;
					}

					type = enum_type;
					return this;
				}
				
				if (!rie){
					temp = Convert.ImplicitConversion (ec, right, l, loc);
					if (temp != null)
						right = temp;
					else {
						Error_OperatorCannotBeApplied ();
						return null;
					}
				} if (!lie){
					temp = Convert.ImplicitConversion (ec, left, r, loc);
					if (temp != null){
						left = temp;
						l = r;
					} else {
						Error_OperatorCannotBeApplied ();
						return null;
					}
				}

				if (oper == Operator.Equality || oper == Operator.Inequality ||
				    oper == Operator.LessThanOrEqual || oper == Operator.LessThan ||
				    oper == Operator.GreaterThanOrEqual || oper == Operator.GreaterThan){
					if (left.Type != right.Type){
						Error_OperatorCannotBeApplied ();
						return null;
					}
					type = TypeManager.bool_type;
					return this;
				}

				if (oper == Operator.BitwiseAnd ||
				    oper == Operator.BitwiseOr ||
				    oper == Operator.ExclusiveOr){
					if (left.Type != right.Type){
						Error_OperatorCannotBeApplied ();
						return null;
					}
					type = l;
					return this;
				}
				Error_OperatorCannotBeApplied ();
				return null;
			}
			
			if (oper == Operator.LeftShift || oper == Operator.RightShift)
				return CheckShiftArguments (ec);

			if (oper == Operator.LogicalOr || oper == Operator.LogicalAnd){
				if (l == TypeManager.bool_type && r == TypeManager.bool_type) {
					type = TypeManager.bool_type;
					return this;
				}

				if (l != r) {
					Error_OperatorCannotBeApplied ();
					return null;
				}

				Expression e = new ConditionalLogicalOperator (
					oper == Operator.LogicalAnd, left, right, l, loc);
				return e.Resolve (ec);
			} 

			Expression orig_left = left;
			Expression orig_right = right;

			//
			// operator & (bool x, bool y)
			// operator | (bool x, bool y)
			// operator ^ (bool x, bool y)
			//
			if (oper == Operator.BitwiseAnd ||
			    oper == Operator.BitwiseOr ||
			    oper == Operator.ExclusiveOr) {
				if (OverloadResolve_PredefinedIntegral (ec)) {
					if (IsConvertible (ec, orig_left, orig_right, TypeManager.bool_type)) {
						Error_OperatorAmbiguous (loc, oper, l, r);
						return null;
					}

					if (oper == Operator.BitwiseOr && l != r && !(orig_right is Constant) && right is OpcodeCast &&
						(r == TypeManager.sbyte_type || r == TypeManager.short_type ||
						 r == TypeManager.int32_type || r == TypeManager.int64_type)) {
							Report.Warning (675, 3, loc, "The operator `|' used on the sign-extended type `{0}'. Consider casting to a smaller unsigned type first",
								TypeManager.CSharpName (r));
					}
					
				} else if (!VerifyApplicable_Predefined (ec, TypeManager.bool_type)) {
					Error_OperatorCannotBeApplied ();
					return null;
				}
				return this;
			}
			
			//
			// Pointer comparison
			//
			if (l.IsPointer && r.IsPointer){
				if (oper == Operator.LessThan || oper == Operator.LessThanOrEqual ||
				    oper == Operator.GreaterThan || oper == Operator.GreaterThanOrEqual){
					type = TypeManager.bool_type;
					return this;
				}
			}

			if (OverloadResolve_PredefinedIntegral (ec)) {
				if (IsApplicable_String (ec, orig_left, orig_right, oper)) {
					Error_OperatorAmbiguous (loc, oper, l, r);
					return null;
				}
			} else if (OverloadResolve_PredefinedFloating (ec)) {
				if (IsConvertible (ec, orig_left, orig_right, TypeManager.decimal_type) ||
				    IsApplicable_String (ec, orig_left, orig_right, oper)) {
					Error_OperatorAmbiguous (loc, oper, l, r);
					return null;
				}
			} else if (VerifyApplicable_Predefined (ec, TypeManager.decimal_type)) {
				if (IsApplicable_String (ec, orig_left, orig_right, oper)) {
					Error_OperatorAmbiguous (loc, oper, l, r);
					return null;
				}
			} else if (!OverloadResolve_PredefinedString (ec, oper)) {
				Error_OperatorCannotBeApplied ();
				return null;
			}

			if (oper == Operator.Equality ||
			    oper == Operator.Inequality ||
			    oper == Operator.LessThanOrEqual ||
			    oper == Operator.LessThan ||
			    oper == Operator.GreaterThanOrEqual ||
			    oper == Operator.GreaterThan)
				type = TypeManager.bool_type;

			l = left.Type;
			r = right.Type;

			if (l == TypeManager.decimal_type || l == TypeManager.string_type || r == TypeManager.string_type) {
				Type lookup = l;
				if (r == TypeManager.string_type)
					lookup = r;
				MethodGroupExpr ops = (MethodGroupExpr) MemberLookup (
					ec.ContainerType, lookup, oper_names [(int) oper],
					MemberTypes.Method, AllBindingFlags, loc);
				ArrayList args = new ArrayList (2);
				args.Add (new Argument (left, Argument.AType.Expression));
				args.Add (new Argument (right, Argument.AType.Expression));
				MethodBase method = Invocation.OverloadResolve (ec, ops, args, true, Location.Null);
				return new BinaryMethod (type, method, args);
			}

			return this;
		}

		Constant EnumLiftUp (Constant left, Constant right)
		{
			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 (left is EnumConstant)
						return left;

					if (left.IsZeroInteger)
						return new EnumConstant (left, right.Type);

					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 (right is EnumConstant || left is EnumConstant)
						break;
					return left;
			}
			Error_OperatorCannotBeApplied (loc, Binary.OperName (oper), left.Type, right.Type);
			return null;
		}

		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 && (bool)lc.GetValue () == false) ||
				 (oper == Operator.LogicalOr && (bool)lc.GetValue () == true))) {

				// TODO: make a sense to resolve unreachable expression as we do for statement
				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))) {
				left = lc = EnumLiftUp (lc, rc);
				if (lc == null)
					return null;

				right = rc = EnumLiftUp (rc, lc);
				if (rc == null)
					return null;
			}

			if (oper == Operator.BitwiseAnd) {
				if (rc != null && rc.IsZeroInteger) {
					return lc is EnumConstant ?
						new EnumConstant (rc, lc.Type):
						rc;
				}

				if (lc != null && lc.IsZeroInteger) {
					return rc is EnumConstant ?
						new EnumConstant (lc, rc.Type):
						lc;
				}
			}
			else if (oper == Operator.BitwiseOr) {
				if (lc is EnumConstant &&
				    rc != null && rc.IsZeroInteger)
					return lc;
				if (rc is EnumConstant &&
				    lc != null && lc.IsZeroInteger)
					return rc;
			} else if (oper == Operator.LogicalAnd) {
				if (rc != null && rc.IsDefaultValue && rc.Type == TypeManager.bool_type)
					return rc;
				if (lc != null && lc.IsDefaultValue && lc.Type == TypeManager.bool_type)
					return lc;
			}

			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;
			}

#if GMCS_SOURCE
			if ((left is NullLiteral || left.Type.IsValueType) &&
			    (right is NullLiteral || right.Type.IsValueType) &&
			    !(left is NullLiteral && right is NullLiteral) &&
			    (TypeManager.IsNullableType (left.Type) || TypeManager.IsNullableType (right.Type)))
				return new Nullable.LiftedBinaryOperator (oper, left, right, loc).Resolve (ec);
#endif

			// Comparison warnings
			if (oper == Operator.Equality || oper == Operator.Inequality ||
			    oper == Operator.LessThanOrEqual || oper == Operator.LessThan ||
			    oper == Operator.GreaterThanOrEqual || oper == Operator.GreaterThan){
				if (left.Equals (right)) {
					Report.Warning (1718, 3, loc, "Comparison made to same variable; did you mean to compare something else?");
				}
				CheckUselessComparison (lc, right.Type);
				CheckUselessComparison (rc, left.Type);
			}

			return ResolveOperator (ec);
		}

		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 CharConstant
				|| 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)
						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;

			if (value != 0) {
				if (IsValueOutOfRange (value, type))
					WarnUselessComparison (type);
				return;
			}
		}

		private 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;
		}

		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;
		}

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

		private void WarnUselessComparison (Type type)
		{
			Report.Warning (652, 2, loc, "Comparison to integral constant is useless; the constant is outside the range of 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 onTrue)
		{
			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 ? onTrue : !onTrue;
				
				//
				// put the constant on the rhs, for simplicity
				//
				if (left is Constant) {
					Expression swap = right;
					right = left;
					left = swap;
				}
				
				if (((Constant) right).IsZeroInteger) {
					left.Emit (ec);
					if (my_on_true)
						ig.Emit (OpCodes.Brtrue, target);
					else
						ig.Emit (OpCodes.Brfalse, target);
					
					return;
				} else if (right is BoolConstant) {
					left.Emit (ec);
					if (my_on_true != ((BoolConstant) right).Value)
						ig.Emit (OpCodes.Brtrue, target);
					else
						ig.Emit (OpCodes.Brfalse, target);
					
					return;
				}

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

				if (onTrue) {
					Label tests_end = ig.DefineLabel ();
					
					left.EmitBranchable (ec, tests_end, false);
					right.EmitBranchable (ec, target, true);
					ig.MarkLabel (tests_end);					
				} else {
					left.EmitBranchable (ec, target, false);
					right.EmitBranchable (ec, target, false);
				}
				
				return;
				
			} else if (oper == Operator.LogicalOr){
				if (onTrue) {
					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, onTrue);
				return;
			}
			
			left.Emit (ec);
			right.Emit (ec);

			Type t = left.Type;
			bool isUnsigned = is_unsigned (t) || t == TypeManager.double_type || t == TypeManager.float_type;
			
			switch (oper){
			case Operator.Equality:
				if (onTrue)
					ig.Emit (OpCodes.Beq, target);
				else
					ig.Emit (OpCodes.Bne_Un, target);
				break;

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

			case Operator.LessThan:
				if (onTrue)
					if (isUnsigned)
						ig.Emit (OpCodes.Blt_Un, target);
					else
						ig.Emit (OpCodes.Blt, target);
				else
					if (isUnsigned)
						ig.Emit (OpCodes.Bge_Un, target);
					else
						ig.Emit (OpCodes.Bge, target);
				break;

			case Operator.GreaterThan:
				if (onTrue)
					if (isUnsigned)
						ig.Emit (OpCodes.Bgt_Un, target);
					else
						ig.Emit (OpCodes.Bgt, target);
				else
					if (isUnsigned)
						ig.Emit (OpCodes.Ble_Un, target);
					else
						ig.Emit (OpCodes.Ble, target);
				break;

			case Operator.LessThanOrEqual:
				if (onTrue)
					if (isUnsigned)
						ig.Emit (OpCodes.Ble_Un, target);
					else
						ig.Emit (OpCodes.Ble, target);
				else
					if (isUnsigned)
						ig.Emit (OpCodes.Bgt_Un, target);
					else
						ig.Emit (OpCodes.Bgt, target);
				break;


			case Operator.GreaterThanOrEqual:
				if (onTrue)
					if (isUnsigned)
						ig.Emit (OpCodes.Bge_Un, target);
					else
						ig.Emit (OpCodes.Bge, target);
				else
					if (isUnsigned)
						ig.Emit (OpCodes.Blt_Un, target);
					else
						ig.Emit (OpCodes.Blt, target);
				break;
			default:
				Console.WriteLine (oper);
				throw new Exception ("what is THAT");
			}
		}
		
		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			Type l = left.Type;
			OpCode opcode;

			//
			// Handle short-circuit operators differently
			// than the rest
			//
			if (oper == Operator.LogicalAnd) {
				Label load_zero = ig.DefineLabel ();
				Label end = ig.DefineLabel ();
								
				left.EmitBranchable (ec, load_zero, false);
				right.Emit (ec);
				ig.Emit (OpCodes.Br, end);
				
				ig.MarkLabel (load_zero);
				ig.Emit (OpCodes.Ldc_I4_0);
				ig.MarkLabel (end);
				return;
			} else if (oper == Operator.LogicalOr) {
				Label load_one = ig.DefineLabel ();
				Label end = ig.DefineLabel ();

				left.EmitBranchable (ec, load_one, true);
				right.Emit (ec);
				ig.Emit (OpCodes.Br, end);
				
				ig.MarkLabel (load_one);
				ig.Emit (OpCodes.Ldc_I4_1);
				ig.MarkLabel (end);
				return;
			}

			left.Emit (ec);
			right.Emit (ec);

			bool isUnsigned = is_unsigned (left.Type);
			
			switch (oper){
			case Operator.Multiply:
				if (ec.CheckState){
					if (l == TypeManager.int32_type || l == TypeManager.int64_type)
						opcode = OpCodes.Mul_Ovf;
					else if (isUnsigned)
						opcode = OpCodes.Mul_Ovf_Un;
					else
						opcode = OpCodes.Mul;
				} else
					opcode = OpCodes.Mul;

				break;

			case Operator.Division:
				if (isUnsigned)
					opcode = OpCodes.Div_Un;
				else
					opcode = OpCodes.Div;
				break;

			case Operator.Modulus:
				if (isUnsigned)
					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 (isUnsigned)
						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 (isUnsigned)
						opcode = OpCodes.Sub_Ovf_Un;
					else
						opcode = OpCodes.Sub;
				} else
					opcode = OpCodes.Sub;
				break;

			case Operator.RightShift:
				if (isUnsigned)
					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)
					opcode = OpCodes.Clt_Un;
				else
					opcode = OpCodes.Clt;
				break;

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

			case Operator.LessThanOrEqual:
				Type lt = left.Type;
				
				if (isUnsigned || (lt == TypeManager.double_type || lt == TypeManager.float_type))
					ig.Emit (OpCodes.Cgt_Un);
				else
					ig.Emit (OpCodes.Cgt);
				ig.Emit (OpCodes.Ldc_I4_0);
				
				opcode = OpCodes.Ceq;
				break;

			case Operator.GreaterThanOrEqual:
				Type le = left.Type;
				
				if (isUnsigned || (le == TypeManager.double_type || le == TypeManager.float_type))
					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 Exception ("This should not happen: Operator = "
						     + oper.ToString ());
			}

			ig.Emit (opcode);
		}
	}

	//
	// Object created by Binary when the binary operator uses an method instead of being
	// a binary operation that maps to a CIL binary operation.
	//
	public class BinaryMethod : Expression {
		public MethodBase method;
		public ArrayList  Arguments;
		
		public BinaryMethod (Type t, MethodBase m, ArrayList args)
		{
			method = m;
			Arguments = args;
			type = t;
			eclass = ExprClass.Value;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			return this;
		}

		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			if (Arguments != null) 
				Invocation.EmitArguments (ec, method, Arguments, false, null);
			
			if (method is MethodInfo)
				ig.Emit (OpCodes.Call, (MethodInfo) method);
			else
				ig.Emit (OpCodes.Call, (ConstructorInfo) method);
		}
	}
	
	//
	// 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 operands;
		bool invalid = false;
		bool emit_conv_done = false;
		//
		// Are we also concating objects?
		//
		bool is_strings_only = true;
		
		public StringConcat (EmitContext ec, Location loc, Expression left, Expression right)
		{
			this.loc = loc;
			type = TypeManager.string_type;
			eclass = ExprClass.Value;
		
			operands = new ArrayList (2);
			Append (ec, left);
			Append (ec, right);
		}
		
		public override Expression DoResolve (EmitContext ec)
		{
			if (invalid)
				return null;
			
			return this;
		}
		
		public void Append (EmitContext ec, Expression operand)
		{
			//
			// Constant folding
			//
			StringConstant sc = operand as StringConstant;
			if (sc != null) {
// TODO: it will be better to do this silently as an optimalization
// int i = 0;
// string s = "" + i;
// because this code has poor performace
//				if (sc.Value.Length == 0)
//					Report.Warning (-300, 3, Location, "Appending an empty string has no effect. Did you intend to append a space string?");

				if (operands.Count != 0) {
					StringConstant last_operand = operands [operands.Count - 1] as StringConstant;
					if (last_operand != null) {
						operands [operands.Count - 1] = new StringConstant (last_operand.Value + ((StringConstant) operand).Value, last_operand.Location);
						return;
					}
				}
			}
			
			//
			// Conversion to object
			//
			if (operand.Type != TypeManager.string_type) {
				Expression no = Convert.ImplicitConversion (ec, operand, TypeManager.object_type, loc);
				
				if (no == null) {
					Binary.Error_OperatorCannotBeApplied (loc, "+", TypeManager.string_type, operand.Type);
					invalid = true;
				}
				operand = no;
			}
			
			operands.Add (operand);
		}

		public override void Emit (EmitContext ec)
		{
			MethodInfo concat_method = null;
			
			//
			// Do conversion to arguments; check for strings only
			//
			
			// This can get called multiple times, so we have to deal with that.
			if (!emit_conv_done) {
				emit_conv_done = true;
				for (int i = 0; i < operands.Count; i ++) {
					Expression e = (Expression) operands [i];
					is_strings_only &= e.Type == TypeManager.string_type;
				}
				
				for (int i = 0; i < operands.Count; i ++) {
					Expression e = (Expression) operands [i];
					
					if (! is_strings_only && e.Type == TypeManager.string_type) {
						// need to make sure this is an object, because the EmitParams
						// method might look at the type of this expression, see it is a
						// string and emit a string [] when we want an object [];
						
						e = new EmptyCast (e, TypeManager.object_type);
					}
					operands [i] = new Argument (e, Argument.AType.Expression);
				}
			}
			
			//
			// Find the right method
			//
			switch (operands.Count) {
			case 1:
				//
				// This should not be possible, because simple constant folding
				// is taken care of in the Binary code.
				//
				throw new Exception ("how did you get here?");
			
			case 2:
				concat_method = is_strings_only ? 
					TypeManager.string_concat_string_string :
					TypeManager.string_concat_object_object ;
				break;
			case 3:
				concat_method = is_strings_only ? 
					TypeManager.string_concat_string_string_string :
					TypeManager.string_concat_object_object_object ;
				break;
			case 4:
				//
				// There is not a 4 param overlaod for object (the one that there is
				// is actually a varargs methods, and is only in corlib because it was
				// introduced there before.).
				//
				if (!is_strings_only)
					goto default;
				
				concat_method = TypeManager.string_concat_string_string_string_string;
				break;
			default:
				concat_method = is_strings_only ? 
					TypeManager.string_concat_string_dot_dot_dot :
					TypeManager.string_concat_object_dot_dot_dot ;
				break;
			}
			
			Invocation.EmitArguments (ec, concat_method, operands, false, null);
			ec.ig.Emit (OpCodes.Call, concat_method);
		}
	}

	//
	// Object created with +/= on delegates
	//
	public class BinaryDelegate : Expression {
		MethodInfo method;
		ArrayList  args;

		public BinaryDelegate (Type t, MethodInfo mi, ArrayList args)
		{
			method = mi;
			this.args = args;
			type = t;
			eclass = ExprClass.Value;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			return this;
		}

		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			Invocation.EmitArguments (ec, method, args, false, null);
			
			ig.Emit (OpCodes.Call, (MethodInfo) method);
			ig.Emit (OpCodes.Castclass, type);
		}

		public Expression Right {
			get {
				Argument arg = (Argument) args [1];
				return arg.Expr;
			}
		}

		public bool IsAddition {
			get {
				return method == TypeManager.delegate_combine_delegate_delegate;
			}
		}
	}
	
	//
	// User-defined conditional logical operator
	public class ConditionalLogicalOperator : Expression {
		Expression left, right;
		bool is_and;

		public ConditionalLogicalOperator (bool is_and, Expression left, Expression right, Type t, Location loc)
		{
			type = t;
			eclass = ExprClass.Value;
			this.loc = loc;
			this.left = left;
			this.right = right;
			this.is_and = is_and;
		}

		protected void Error19 ()
		{
			Binary.Error_OperatorCannotBeApplied (loc, is_and ? "&&" : "||", left.GetSignatureForError (), right.GetSignatureForError ());
		}

		protected void Error218 ()
		{
			Error (218, "The type ('" + TypeManager.CSharpName (type) + "') must contain " +
			       "declarations of operator true and operator false");
		}

		Expression op_true, op_false, op;
		LocalTemporary left_temp;

		public override Expression DoResolve (EmitContext ec)
		{
			MethodInfo method;
			Expression operator_group;

			operator_group = MethodLookup (ec.ContainerType, type, is_and ? "op_BitwiseAnd" : "op_BitwiseOr", loc);
			if (operator_group == null) {
				Error19 ();
				return null;
			}

			left_temp = new LocalTemporary (type);

			ArrayList arguments = new ArrayList ();
			arguments.Add (new Argument (left_temp, Argument.AType.Expression));
			arguments.Add (new Argument (right, Argument.AType.Expression));
			method = Invocation.OverloadResolve (
				ec, (MethodGroupExpr) operator_group, arguments, false, loc)
				as MethodInfo;
			if (method == null) {
				Error19 ();
				return null;
			}

			if (method.ReturnType != type) {
				Report.Error (217, loc, "In order to be applicable as a short circuit operator a user-defined logical operator `{0}' " +
						"must have the same return type as the type of its 2 parameters", TypeManager.CSharpSignature (method));
				return null;
			}

			op = new StaticCallExpr (method, arguments, loc);

			op_true = GetOperatorTrue (ec, left_temp, loc);
			op_false = GetOperatorFalse (ec, left_temp, loc);
			if ((op_true == null) || (op_false == null)) {
				Error218 ();
				return null;
			}

			return this;
		}

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

			left.Emit (ec);
			left_temp.Store (ec);

			(is_and ? op_false : op_true).EmitBranchable (ec, false_target, false);
			left_temp.Emit (ec);
			ig.Emit (OpCodes.Br, end_target);
			ig.MarkLabel (false_target);
			op.Emit (ec);
			ig.MarkLabel (end_target);

			// We release 'left_temp' here since 'op' may refer to it too
			left_temp.Release (ec);
		}
	}

	public class PointerArithmetic : Expression {
		Expression left, right;
		bool is_add;

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

		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 = TypeManager.HasElementType (op_type) ?
				element = TypeManager.GetElementType (op_type) :
				element = AttributeTester.GetFixedBuffer (((FieldExpr)left).FieldInfo).ElementType;

			int size = GetTypeSize (element);
			Type rtype = right.Type;
			
			if (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)
				//
				left.Emit (ec);
				ig.Emit (OpCodes.Conv_I);

				Constant right_const = right as Constant;
				if (right_const != null && size != 0) {
					Expression ex = ConstantFold.BinaryFold (ec, Binary.Operator.Multiply, new IntConstant (size, right.Location), right_const, loc);
					if (ex == null)
						return;
					ex.Emit (ec);
				} else {
					right.Emit (ec);
					if (size != 1){
						if (size == 0)
							ig.Emit (OpCodes.Sizeof, element);
						else 
							IntLiteral.EmitInt (ig, size);
						if (rtype == TypeManager.int64_type)
							ig.Emit (OpCodes.Conv_I8);
						else if (rtype == TypeManager.uint64_type)
							ig.Emit (OpCodes.Conv_U8);
						ig.Emit (OpCodes.Mul);
					}
				}
				
				if (rtype == TypeManager.int64_type || rtype == TypeManager.uint64_type)
					ig.Emit (OpCodes.Conv_I);
				
				if (is_add)
					ig.Emit (OpCodes.Add);
				else
					ig.Emit (OpCodes.Sub);
			}
		}
	}
	
	/// <summary>
	///   Implements the ternary conditional operator (?:)
	/// </summary>
	public class Conditional : Expression {
		Expression expr, trueExpr, falseExpr;
		
		public Conditional (Expression expr, Expression trueExpr, Expression falseExpr)
		{
			this.expr = expr;
			this.trueExpr = trueExpr;
			this.falseExpr = falseExpr;
			this.loc = expr.Location;
		}

		public Expression Expr {
			get {
				return expr;
			}
		}

		public Expression TrueExpr {
			get {
				return trueExpr;
			}
		}

		public Expression FalseExpr {
			get {
				return falseExpr;
			}
		}

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

			if (expr == null)
				return null;

#if GMCS_SOURCE
			if (TypeManager.IsNullableValueType (expr.Type))
				return new Nullable.LiftedConditional (expr, trueExpr, falseExpr, loc).Resolve (ec);
#endif
			
			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 = ?");
			}

			trueExpr = trueExpr.Resolve (ec);
			falseExpr = falseExpr.Resolve (ec);

			if (trueExpr == null || falseExpr == null)
				return null;

			eclass = ExprClass.Value;
			if (trueExpr.Type == falseExpr.Type) {
				type = trueExpr.Type;
				if (type == TypeManager.null_type) {
					// TODO: probably will have to implement ConditionalConstant
					// to call method without return constant as well
					Report.Warning (-101, 1, loc, "Conditional expression will always return same value");
					return trueExpr;
				}
			} else {
				Expression conv;
				Type true_type = trueExpr.Type;
				Type false_type = falseExpr.Type;

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

			// Dead code optimalization
			if (expr is BoolConstant){
				BoolConstant bc = (BoolConstant) expr;

				Report.Warning (429, 4, bc.Value ? falseExpr.Location : trueExpr.Location, "Unreachable expression code detected");
				return bc.Value ? trueExpr : falseExpr;
			}

			return this;
		}

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

	}

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

		public abstract Variable Variable {
			get;
		}

		public abstract bool IsRef {
			get;
		}

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

		//
		// 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)
		{
			Report.Debug (64, "VARIABLE EMIT LOAD", this, Variable, type, loc);
			if (!prepared)
				Variable.EmitInstance (ec);
			Variable.Emit (ec);
		}
		
		public void Emit (EmitContext ec, bool leave_copy)
		{
			Report.Debug (64, "VARIABLE EMIT", this, Variable, type, IsRef, loc);

			EmitLoad (ec);

			if (IsRef) {
				if (prepared)
					ec.ig.Emit (OpCodes.Dup);
	
				//
				// 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 || Variable.NeedsTemporary) {
					temp = new LocalTemporary (Type);
					temp.Store (ec);
				}
			}
		}

		public void EmitAssign (EmitContext ec, Expression source, bool leave_copy,
					bool prepare_for_load)
		{
			Report.Debug (64, "VARIABLE EMIT ASSIGN", this, Variable, type, IsRef,
				      source, loc);

			ILGenerator ig = ec.ig;
			prepared = prepare_for_load;

			Variable.EmitInstance (ec);
			if (prepare_for_load && Variable.HasInstance)
				ig.Emit (OpCodes.Dup);
			else if (IsRef && !prepared)
				Variable.Emit (ec);

			source.Emit (ec);

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

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

			if (temp != null) {
				temp.Emit (ec);
				temp.Release (ec);
			}
		}
		
		public void AddressOf (EmitContext ec, AddressOp mode)
		{
			Variable.EmitInstance (ec);
			Variable.EmitAddressOf (ec);
		}
	}

	/// <summary>
	///   Local variables
	/// </summary>
	public class LocalVariableReference : VariableReference, IVariable {
		public readonly string Name;
		public readonly Block Block;
		public LocalInfo local_info;
		bool is_readonly;
		Variable variable;

		public LocalVariableReference (Block block, string name, Location l)
		{
			Block = block;
			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 VariableInfo VariableInfo {
			get { return local_info.VariableInfo; }
		}

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

		public bool IsReadOnly {
			get { return is_readonly; }
		}

		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);
				is_readonly = local_info.ReadOnly;
			}
		}

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

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

			if (!VerifyAssigned (ec))
				return null;

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

				ScopeInfo scope = local_info.Block.CreateScopeInfo ();
				variable = scope.AddLocal (local_info);
				type = variable.Type;
			}

			return this;
		}

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

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

			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 {
					code = 1656; msg = "Cannot assign to `{0}' because it is a `{1}'";
				}
				Report.Error (code, loc, msg, Name, local_info.GetReadOnlyContext ());
				return null;
			}

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

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

			return DoResolveBase (ec);
		}

		public bool VerifyFixed ()
		{
			// A local Variable is always fixed.
			return true;
		}

		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;
		}

		public override Variable Variable {
			get { return variable != null ? variable : local_info.Variable; }
		}

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

	/// <summary>
	///   This represents a reference to a parameter in the intermediate
	///   representation.
	/// </summary>
	public class ParameterReference : VariableReference, IVariable {
		Parameter par;
		string name;
		int idx;
		Block block;
		VariableInfo vi;
		public bool is_ref, is_out;

		public bool IsOut {
			get {
				return is_out;
			}
		}

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

		public string Name {
			get {
				return name;
			}
		}

		public Parameter Parameter {
			get {
				return par;
			}
		}

		Variable variable;
		
		public ParameterReference (Parameter par, Block block, int idx, Location loc)
		{
			this.par = par;
			this.name = par.Name;
			this.block = block;
			this.idx  = idx;
			this.loc = loc;
			eclass = ExprClass.Variable;
		}

		public VariableInfo VariableInfo {
			get { return vi; }
		}

		public override Variable Variable {
			get { return variable != null ? variable : par.Variable; }
		}

		public bool VerifyFixed ()
		{
			// A parameter is fixed if it's a value parameter (i.e., no modifier like out, ref, param).
			return par.ModFlags == Parameter.Modifier.NONE;
		}

		public bool IsAssigned (EmitContext ec, Location loc)
		{
			if (!ec.DoFlowAnalysis || !is_out || ec.CurrentBranching.IsAssigned (vi))
				return true;

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

		public bool IsFieldAssigned (EmitContext ec, string field_name, Location loc)
		{
			if (!ec.DoFlowAnalysis || !is_out || ec.CurrentBranching.IsFieldAssigned (vi, field_name))
				return true;

			Report.Error (170, loc,
				      "Use of possibly unassigned field `" + field_name + "'");
			return false;
		}

		public void SetAssigned (EmitContext ec)
		{
			if (is_out && ec.DoFlowAnalysis)
				ec.CurrentBranching.SetAssigned (vi);
		}

		public void SetFieldAssigned (EmitContext ec, string field_name)
		{
			if (is_out && ec.DoFlowAnalysis)
				ec.CurrentBranching.SetFieldAssigned (vi, field_name);
		}

		protected bool DoResolveBase (EmitContext ec)
		{
			if (!par.Resolve (ec)) {
				//TODO:
			}

			type = par.ParameterType;
			Parameter.Modifier mod = par.ModFlags;
			is_ref = (mod & Parameter.Modifier.ISBYREF) != 0;
			is_out = (mod & Parameter.Modifier.OUT) == Parameter.Modifier.OUT;
			eclass = ExprClass.Variable;

			if (is_out)
				vi = block.ParameterMap [idx];

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

			if (is_ref && !block.Toplevel.IsLocalParameter (name)){
				Report.Error (1628, Location,
					      "Cannot use ref or out parameter `{0}' inside an " +
					      "anonymous method block", par.Name);
				return false;
			}

			if (!am.IsIterator && block.Toplevel.IsLocalParameter (name))
				return true;

			RootScopeInfo host = null;
			ToplevelBlock toplevel = block.Toplevel;
			while (toplevel != null) {
				if (toplevel.IsLocalParameter (name))
					break;

				toplevel = toplevel.Container;
			}

			ScopeInfo scope = toplevel.CreateScopeInfo ();
			variable = scope.AddParameter (par, idx);
			type = variable.Type;
			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 && block == pr.block;
		}

		//
		// 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;

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

			return this;
		}

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

			SetAssigned (ec);

			return this;
		}

		static public void EmitLdArg (ILGenerator ig, int x)
		{
			if (x <= 255){
				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: ig.Emit (OpCodes.Ldarg_S, (byte) x); break;
				}
			} else
				ig.Emit (OpCodes.Ldarg, x);
		}
		
		public override string ToString ()
		{
			return "ParameterReference[" + name + "]";
		}
	}
	
	/// <summary>
	///   Used for arguments to New(), Invocation()
	/// </summary>
	public class Argument {
		public enum AType : byte {
			Expression,
			Ref,
			Out,
			ArgList
		};

		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 {
				if (ArgType == AType.Ref || ArgType == AType.Out)
					return TypeManager.GetReferenceType (Expr.Type);
				else
					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 static string FullDesc (Argument a)
		{
			if (a.ArgType == AType.ArgList)
				return "__arglist";

			return (a.ArgType == AType.Ref ? "ref " :
				(a.ArgType == AType.Out ? "out " : "")) +
				TypeManager.CSharpName (a.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)
		{
			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);
		}
	}

	/// <summary>
	///   Invocation of methods or delegates.
	/// </summary>
	public class Invocation : ExpressionStatement {
		public readonly ArrayList Arguments;

		Expression expr;
		MethodBase method = null;
		
		//
		// arguments is an ArrayList, but we do not want to typecast,
		// as it might be null.
		//
		// FIXME: only allow expr to be a method invocation or a
		// delegate invocation (7.5.5)
		//
		public Invocation (Expression expr, ArrayList arguments)
		{
			this.expr = expr;
			Arguments = arguments;
			loc = expr.Location;
		}

		public Expression Expr {
			get {
				return expr;
			}
		}

		/// <summary>
		///   Determines "better conversion" as specified in 14.4.2.3
		///
                ///    Returns : p    if a->p is better,
 		///              q    if a->q is better,
		///              null if neither is better
		/// </summary>
		static Type BetterConversion (EmitContext ec, Argument a, Type p, Type q)
		{
			Type argument_type = TypeManager.TypeToCoreType (a.Type);
			Expression argument_expr = a.Expr;

			if (argument_type == null)
				throw new Exception ("Expression of type " + a.Expr +
                                                     " does not resolve its type");

			if (p == null || q == null)
				throw new InternalErrorException ("BetterConversion Got a null conversion");

			if (p == q)
				return null;

			if (argument_expr is NullLiteral) {
				//
				// If the argument is null and one of the types to compare is 'object' and
				// the other is a reference type, we prefer the other.
				//
				// This follows from the usual rules:
				//   * There is an implicit conversion from 'null' to type 'object'
				//   * There is an implicit conversion from 'null' to any reference type
				//   * There is an implicit conversion from any reference type to type 'object'
				//   * There is no implicit conversion from type 'object' to other reference types
				//  => Conversion of 'null' to a reference type is better than conversion to 'object'
				//
				//  FIXME: This probably isn't necessary, since the type of a NullLiteral is the 
				//         null type. I think it used to be 'object' and thus needed a special 
				//         case to avoid the immediately following two checks.
				//
				if (!p.IsValueType && q == TypeManager.object_type)
					return p;
				if (!q.IsValueType && p == TypeManager.object_type)
					return q;
			}
                                
			if (argument_type == p)
				return p;

			if (argument_type == q)
				return q;

			Expression p_tmp = new EmptyExpression (p);
			Expression q_tmp = new EmptyExpression (q);

			bool p_to_q = Convert.ImplicitConversionExists (ec, p_tmp, q);
			bool q_to_p = Convert.ImplicitConversionExists (ec, q_tmp, p);

			if (p_to_q && !q_to_p)
				return p;

			if (q_to_p && !p_to_q)
				return q;

			if (p == TypeManager.sbyte_type)
				if (q == TypeManager.byte_type || q == TypeManager.ushort_type ||
				    q == TypeManager.uint32_type || q == TypeManager.uint64_type)
					return p;
			if (q == TypeManager.sbyte_type)
				if (p == TypeManager.byte_type || p == TypeManager.ushort_type ||
				    p == TypeManager.uint32_type || p == TypeManager.uint64_type)
					return q;

			if (p == TypeManager.short_type)
				if (q == TypeManager.ushort_type || q == TypeManager.uint32_type ||
				    q == TypeManager.uint64_type)
					return p;
			if (q == TypeManager.short_type)
				if (p == TypeManager.ushort_type || p == TypeManager.uint32_type ||
				    p == TypeManager.uint64_type)
					return q;

			if (p == TypeManager.int32_type)
				if (q == TypeManager.uint32_type || q == TypeManager.uint64_type)
					return p;
			if (q == TypeManager.int32_type)
				if (p == TypeManager.uint32_type || p == TypeManager.uint64_type)
					return q;

			if (p == TypeManager.int64_type)
				if (q == TypeManager.uint64_type)
					return p;
			if (q == TypeManager.int64_type)
				if (p == TypeManager.uint64_type)
					return q;

			return null;
		}

		static Type MoreSpecific (Type p, Type q)
		{
			if (TypeManager.IsGenericParameter (p) && !TypeManager.IsGenericParameter (q))
				return q;
			if (!TypeManager.IsGenericParameter (p) && TypeManager.IsGenericParameter (q))
				return p;

			if (TypeManager.HasElementType (p)) {
				Type pe = TypeManager.GetElementType (p);
				Type qe = TypeManager.GetElementType (q);
				Type specific = MoreSpecific (pe, qe);
				if (specific == pe)
					return p;
				if (specific == qe)
					return q;
			} else if (TypeManager.IsGenericType (p)) {
				Type[] pargs = TypeManager.GetTypeArguments (p);
				Type[] qargs = TypeManager.GetTypeArguments (q);

				bool p_specific_at_least_once = false;
				bool q_specific_at_least_once = false;

				for (int i = 0; i < pargs.Length; i++) {
					Type specific = MoreSpecific (pargs [i], qargs [i]);
					if (specific == pargs [i])
						p_specific_at_least_once = true;
					if (specific == qargs [i])
						q_specific_at_least_once = true;
				}

				if (p_specific_at_least_once && !q_specific_at_least_once)
					return p;
				if (!p_specific_at_least_once && q_specific_at_least_once)
					return q;
			}

			return null;
		}
		
		/// <summary>
		///   Determines "Better function" between candidate
                ///   and the current best match
		/// </summary>
		/// <remarks>
		///    Returns a boolean indicating :
		///     false if candidate ain't better
		///     true  if candidate is better than the current best match
		/// </remarks>
		static bool BetterFunction (EmitContext ec, ArrayList args, int argument_count,
					    MethodBase candidate, bool candidate_params,
					    MethodBase best, bool best_params)
		{
			ParameterData candidate_pd = TypeManager.GetParameterData (candidate);
			ParameterData best_pd = TypeManager.GetParameterData (best);
		
			bool better_at_least_one = false;
			bool same = true;
			for (int j = 0; j < argument_count; ++j) {
				Argument a = (Argument) args [j];

				Type ct = TypeManager.TypeToCoreType (candidate_pd.ParameterType (j));
				Type bt = TypeManager.TypeToCoreType (best_pd.ParameterType (j));

				if (candidate_pd.ParameterModifier (j) == Parameter.Modifier.PARAMS)
					if (candidate_params)
						ct = TypeManager.GetElementType (ct);

				if (best_pd.ParameterModifier (j) == Parameter.Modifier.PARAMS)
					if (best_params)
						bt = TypeManager.GetElementType (bt);

				if (ct.Equals (bt))
					continue;

				same = false;
				Type better = BetterConversion (ec, a, ct, bt);

				// for each argument, the conversion to 'ct' should be no worse than 
				// the conversion to 'bt'.
				if (better == bt)
					return false;

				// for at least one argument, the conversion to 'ct' should be better than 
				// the conversion to 'bt'.
				if (better == ct)
					better_at_least_one = true;
			}

			if (better_at_least_one)
				return true;

			//
			// This handles the case
			//
			//   Add (float f1, float f2, float f3);
			//   Add (params decimal [] foo);
			//
			// The call Add (3, 4, 5) should be ambiguous.  Without this check, the
			// first candidate would've chosen as better.
			//
			if (!same)
				return false;

			//
			// The two methods have equal parameter types.  Now apply tie-breaking rules
			//
			if (TypeManager.IsGenericMethod (best) && !TypeManager.IsGenericMethod (candidate))
				return true;
			if (!TypeManager.IsGenericMethod (best) && TypeManager.IsGenericMethod (candidate))
				return false;

			//
			// This handles the following cases:
			//
			//   Trim () is better than Trim (params char[] chars)
			//   Concat (string s1, string s2, string s3) is better than
			//     Concat (string s1, params string [] srest)
			//   Foo (int, params int [] rest) is better than Foo (params int [] rest)
			//
			if (!candidate_params && best_params)
				return true;
			if (candidate_params && !best_params)
				return false;

			int candidate_param_count = candidate_pd.Count;
			int best_param_count = best_pd.Count;

			if (candidate_param_count != best_param_count)
				// can only happen if (candidate_params && best_params)
				return candidate_param_count > best_param_count;

			//
			// now, both methods have the same number of parameters, and the parameters have the same types
			// Pick the "more specific" signature
			//

			MethodBase orig_candidate = TypeManager.DropGenericMethodArguments (candidate);
			MethodBase orig_best = TypeManager.DropGenericMethodArguments (best);

			ParameterData orig_candidate_pd = TypeManager.GetParameterData (orig_candidate);
			ParameterData orig_best_pd = TypeManager.GetParameterData (orig_best);

			bool specific_at_least_once = false;
			for (int j = 0; j < candidate_param_count; ++j) {
				Type ct = TypeManager.TypeToCoreType (orig_candidate_pd.ParameterType (j));
				Type bt = TypeManager.TypeToCoreType (orig_best_pd.ParameterType (j));
				if (ct.Equals (bt))
					continue;
				Type specific = MoreSpecific (ct, bt);
				if (specific == bt)
					return false;
				if (specific == ct)
					specific_at_least_once = true;
			}

			if (specific_at_least_once)
				return true;

			// FIXME: handle lifted operators
			// ...

			return false;
		}

		internal static bool IsOverride (MethodBase cand_method, MethodBase base_method)
		{
			if (!IsAncestralType (base_method.DeclaringType, cand_method.DeclaringType))
				return false;

			ParameterData cand_pd = TypeManager.GetParameterData (cand_method);
			ParameterData base_pd = TypeManager.GetParameterData (base_method);
		
			if (cand_pd.Count != base_pd.Count)
				return false;

			for (int j = 0; j < cand_pd.Count; ++j) {
				Parameter.Modifier cm = cand_pd.ParameterModifier (j);
				Parameter.Modifier bm = base_pd.ParameterModifier (j);
				Type ct = TypeManager.TypeToCoreType (cand_pd.ParameterType (j));
				Type bt = TypeManager.TypeToCoreType (base_pd.ParameterType (j));

				if (cm != bm || ct != bt)
					return false;
			}

			return true;
		}

		public static string FullMethodDesc (MethodBase mb)
		{
			if (mb == null)
				return "";

			StringBuilder sb;
			if (mb is MethodInfo) {
				sb = new StringBuilder (TypeManager.CSharpName (((MethodInfo) mb).ReturnType));
				sb.Append (" ");
			}
			else
				sb = new StringBuilder ();

			sb.Append (TypeManager.CSharpSignature (mb));
			return sb.ToString ();
		}

		public static MethodGroupExpr MakeUnionSet (Expression mg1, Expression mg2, Location loc)
		{
			MemberInfo [] miset;
			MethodGroupExpr union;

			if (mg1 == null) {
				if (mg2 == null)
					return null;
				return (MethodGroupExpr) mg2;
			} else {
				if (mg2 == null)
					return (MethodGroupExpr) mg1;
			}
			
			MethodGroupExpr left_set = null, right_set = null;
			int length1 = 0, length2 = 0;
			
			left_set = (MethodGroupExpr) mg1;
			length1 = left_set.Methods.Length;
			
			right_set = (MethodGroupExpr) mg2;
			length2 = right_set.Methods.Length;
			
			ArrayList common = new ArrayList ();

			foreach (MethodBase r in right_set.Methods){
				if (TypeManager.ArrayContainsMethod (left_set.Methods, r))
					common.Add (r);
			}

			miset = new MemberInfo [length1 + length2 - common.Count];
			left_set.Methods.CopyTo (miset, 0);
			
			int k = length1;

			foreach (MethodBase r in right_set.Methods) {
				if (!common.Contains (r))
					miset [k++] = r;
			}

			union = new MethodGroupExpr (miset, loc);
			
			return union;
		}

		public static bool IsParamsMethodApplicable (EmitContext ec, MethodGroupExpr me,
							     ArrayList arguments, int arg_count,
							     ref MethodBase candidate)
		{
			return IsParamsMethodApplicable (
				ec, me, arguments, arg_count, false, ref candidate) ||
				IsParamsMethodApplicable (
					ec, me, arguments, arg_count, true, ref candidate);


		}

		static bool IsParamsMethodApplicable (EmitContext ec, MethodGroupExpr me,
						      ArrayList arguments, int arg_count,
						      bool do_varargs, ref MethodBase candidate)
		{
#if GMCS_SOURCE
			if (!me.HasTypeArguments &&
			    !TypeManager.InferParamsTypeArguments (ec, arguments, ref candidate))
				return false;

			if (TypeManager.IsGenericMethodDefinition (candidate))
				throw new InternalErrorException ("a generic method definition took part in overload resolution");
#endif

			return IsParamsMethodApplicable (
				ec, arguments, arg_count, candidate, do_varargs);
		}

		/// <summary>
		///   Determines if the candidate method, if a params method, is applicable
		///   in its expanded form to the given set of arguments
		/// </summary>
		static bool IsParamsMethodApplicable (EmitContext ec, ArrayList arguments,
						      int arg_count, MethodBase candidate,
						      bool do_varargs)
		{
			ParameterData pd = TypeManager.GetParameterData (candidate);

			int pd_count = pd.Count;
			if (pd_count == 0)
				return false;

			int count = pd_count - 1;
			if (do_varargs) {
				if (pd.ParameterModifier (count) != Parameter.Modifier.ARGLIST)
					return false;
				if (pd_count != arg_count)
					return false;
			} else {
				if (!pd.HasParams)
					return false;
			}
			
			if (count > arg_count)
				return false;
			
			if (pd_count == 1 && arg_count == 0)
				return true;

			//
			// If we have come this far, the case which
			// remains is when the number of parameters is
			// less than or equal to the argument count.
			//
			for (int i = 0; i < count; ++i) {

				Argument a = (Argument) arguments [i];

				Parameter.Modifier a_mod = a.Modifier & 
					(unchecked (~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK)));
				Parameter.Modifier p_mod = pd.ParameterModifier (i) &
					(unchecked (~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK)));

				if (a_mod == p_mod) {

					if (a_mod == Parameter.Modifier.NONE)
						if (!Convert.ImplicitConversionExists (ec,
                                                                                       a.Expr,
                                                                                       pd.ParameterType (i)))
				return false;

					if ((a_mod & Parameter.Modifier.ISBYREF) != 0) {
						Type pt = pd.ParameterType (i);

						if (!pt.IsByRef)
							pt = TypeManager.GetReferenceType (pt);
						
						if (pt != a.Type)
							return false;
					}
				} else
					return false;
				
			}

			if (do_varargs) {
				Argument a = (Argument) arguments [count];
				if (!(a.Expr is Arglist))
					return false;

				return true;
			}

			Type element_type = TypeManager.GetElementType (pd.ParameterType (pd_count - 1));

			for (int i = pd_count - 1; i < arg_count; i++) {
				Argument a = (Argument) arguments [i];

				if (!Convert.ImplicitConversionExists (ec, a.Expr, element_type))
					return false;
			}
			
			return true;
		}

		public static bool IsApplicable (EmitContext ec, MethodGroupExpr me,
						 ArrayList arguments, int arg_count,
						 ref MethodBase candidate)
		{
#if GMCS_SOURCE
			if (!me.HasTypeArguments &&
			    !TypeManager.InferTypeArguments (arguments, ref candidate))
				return false;

			if (TypeManager.IsGenericMethodDefinition (candidate))
				throw new InternalErrorException ("a generic method definition took part in overload resolution");
#endif

			return IsApplicable (ec, arguments, arg_count, candidate);
		}

		/// <summary>
		///   Determines if the candidate method is applicable (section 14.4.2.1)
		///   to the given set of arguments
		/// </summary>
		public static bool IsApplicable (EmitContext ec, ArrayList arguments, int arg_count,
			MethodBase candidate)
		{
			ParameterData pd = TypeManager.GetParameterData (candidate);

			if (arg_count != pd.Count)
				return false;

			for (int i = arg_count; i > 0; ) {
				i--;

				Argument a = (Argument) arguments [i];

				Parameter.Modifier a_mod = a.Modifier &
					~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK);

				Parameter.Modifier p_mod = pd.ParameterModifier (i) &
					~(Parameter.Modifier.OUTMASK | Parameter.Modifier.REFMASK | Parameter.Modifier.PARAMS);

				if (a_mod == p_mod) {
					Type pt = pd.ParameterType (i);

					if (a_mod == Parameter.Modifier.NONE) {
                                                if (!TypeManager.IsEqual (a.Type, pt) &&
						    !Convert.ImplicitConversionExists (ec, a.Expr, pt))
							return false;
						continue;
					}
					
					if (pt != a.Type)
						return false;
				} else
					return false;
			}

			return true;
		}

		static internal bool IsAncestralType (Type first_type, Type second_type)
		{
			return first_type != second_type &&
				(TypeManager.IsSubclassOf (second_type, first_type) ||
				 TypeManager.ImplementsInterface (second_type, first_type));
		}
		
		/// <summary>
		///   Find the Applicable Function Members (7.4.2.1)
		///
		///   me: Method Group expression with the members to select.
		///       it might contain constructors or methods (or anything
		///       that maps to a method).
		///
		///   Arguments: ArrayList containing resolved Argument objects.
		///
		///   loc: The location if we want an error to be reported, or a Null
		///        location for "probing" purposes.
		///
		///   Returns: The MethodBase (either a ConstructorInfo or a MethodInfo)
		///            that is the best match of me on Arguments.
		///
		/// </summary>
		public static MethodBase OverloadResolve (EmitContext ec, MethodGroupExpr me,
							  ArrayList Arguments, bool may_fail,
							  Location loc)
		{
			MethodBase method = null;
			bool method_params = false;
			Type applicable_type = null;
			int arg_count = 0;
			ArrayList candidates = new ArrayList (2);
			ArrayList candidate_overrides = null;

                        //
                        // Used to keep a map between the candidate
                        // and whether it is being considered in its
                        // normal or expanded form
                        //
                        // false is normal form, true is expanded form
                        //
                        Hashtable candidate_to_form = null;

			if (Arguments != null)
				arg_count = Arguments.Count;

			if ((me.Name == "Invoke") &&
				TypeManager.IsDelegateType (me.DeclaringType)) {
				Error_InvokeOnDelegate (loc);
				return null;
			}

			MethodBase[] methods = me.Methods;

			int nmethods = methods.Length;

			if (!me.IsBase) {
				//
				// Methods marked 'override' don't take part in 'applicable_type'
				// computation, nor in the actual overload resolution.
				// However, they still need to be emitted instead of a base virtual method.
				// So, we salt them away into the 'candidate_overrides' array.
				//
				// In case of reflected methods, we replace each overriding method with
				// its corresponding base virtual method.  This is to improve compatibility
				// with non-C# libraries which change the visibility of overrides (#75636)
				//
				int j = 0;
				for (int i = 0; i < methods.Length; ++i) {
					MethodBase m = methods [i];
#if GMCS_SOURCE
					Type [] gen_args = null;
					if (m.IsGenericMethod && !m.IsGenericMethodDefinition)
						gen_args = m.GetGenericArguments ();
#endif
					if (TypeManager.IsOverride (m)) {
						if (candidate_overrides == null)
							candidate_overrides = new ArrayList ();
						candidate_overrides.Add (m);
						m = TypeManager.TryGetBaseDefinition (m);
#if GMCS_SOURCE
						if (m != null && gen_args != null) {
							if (!m.IsGenericMethodDefinition)
								throw new InternalErrorException ("GetBaseDefinition didn't return a GenericMethodDefinition");
							m = ((MethodInfo) m).MakeGenericMethod (gen_args);
						}
#endif
					}
					if (m != null)
						methods [j++] = m;
				}
				nmethods = j;
			}

			int applicable_errors = Report.Errors;
			
			//
			// First we construct the set of applicable methods
			//
 			bool is_sorted = true;
			for (int i = 0; i < nmethods; i++){
				Type decl_type = methods [i].DeclaringType;

				//
				// If we have already found an applicable method
				// we eliminate all base types (Section 14.5.5.1)
				//
				if (applicable_type != null && IsAncestralType (decl_type, applicable_type))
					continue;

				//
				// Check if candidate is applicable (section 14.4.2.1)
				//   Is candidate applicable in normal form?
				//
				bool is_applicable = IsApplicable (ec, me, Arguments, arg_count, ref methods [i]);

				if (!is_applicable && IsParamsMethodApplicable (ec, me, Arguments, arg_count, ref methods [i])) {
					MethodBase candidate = methods [i];
					if (candidate_to_form == null)
						candidate_to_form = new PtrHashtable ();
					candidate_to_form [candidate] = candidate;
					// Candidate is applicable in expanded form
					is_applicable = true;
				}

				if (!is_applicable)
					continue;

				candidates.Add (methods [i]);

				if (applicable_type == null)
					applicable_type = decl_type;
				else if (applicable_type != decl_type) {
					is_sorted = false;
					if (IsAncestralType (applicable_type, decl_type))
						applicable_type = decl_type;
				}
			}

			if (applicable_errors != Report.Errors)
				return null;
			
			int candidate_top = candidates.Count;

			if (applicable_type == null) {
				//
				// Okay so we have failed to find anything so we
				// return by providing info about the closest match
				//
				int errors = Report.Errors;
				for (int i = 0; i < nmethods; ++i) {
					MethodBase c = (MethodBase) methods [i];
					ParameterData pd = TypeManager.GetParameterData (c);

					if (pd.Count != arg_count)
						continue;

#if GMCS_SOURCE
					if (!TypeManager.InferTypeArguments (Arguments, ref c))
						continue;
					if (TypeManager.IsGenericMethodDefinition (c))
						continue;
#endif

					VerifyArgumentsCompat (ec, Arguments, arg_count,
						c, false, null, may_fail, loc);

					if (!may_fail && errors == Report.Errors)
						throw new InternalErrorException (
							"VerifyArgumentsCompat and IsApplicable do not agree; " +
							"likely reason: ImplicitConversion and ImplicitConversionExists have gone out of sync");

					break;
				}

				if (!may_fail && errors == Report.Errors) {
					string report_name = me.Name;
					if (report_name == ".ctor")
						report_name = TypeManager.CSharpName (me.DeclaringType);
                                        
#if GMCS_SOURCE
					//
					// Type inference
					//
					for (int i = 0; i < methods.Length; ++i) {
						MethodBase c = methods [i];
						ParameterData pd = TypeManager.GetParameterData (c);

						if (pd.Count != arg_count)
							continue;

						if (TypeManager.InferTypeArguments (Arguments, ref c))
							continue;

						Report.Error (
							411, loc, "The type arguments for " +
							"method `{0}' cannot be infered from " +
							"the usage. Try specifying the type " +
							"arguments explicitly.", report_name);
						return null;
					}
#endif

					Error_WrongNumArguments (loc, report_name, arg_count);
				}
                                
				return null;
			}

			if (!is_sorted) {
				//
				// At this point, applicable_type is _one_ of the most derived types
				// in the set of types containing the methods in this MethodGroup.
				// Filter the candidates so that they only contain methods from the
				// most derived types.
				//

				int finalized = 0; // Number of finalized candidates

				do {
					// Invariant: applicable_type is a most derived type
					
					// We'll try to complete Section 14.5.5.1 for 'applicable_type' by 
					// eliminating all it's base types.  At the same time, we'll also move
					// every unrelated type to the end of the array, and pick the next
					// 'applicable_type'.

					Type next_applicable_type = null;
					int j = finalized; // where to put the next finalized candidate
					int k = finalized; // where to put the next undiscarded candidate
					for (int i = finalized; i < candidate_top; ++i) {
						MethodBase candidate = (MethodBase) candidates [i];
						Type decl_type = candidate.DeclaringType;

						if (decl_type == applicable_type) {
							candidates [k++] = candidates [j];
							candidates [j++] = candidates [i];
							continue;
						}

						if (IsAncestralType (decl_type, applicable_type))
							continue;

						if (next_applicable_type != null &&
						    IsAncestralType (decl_type, next_applicable_type))
							continue;

						candidates [k++] = candidates [i];

						if (next_applicable_type == null ||
						    IsAncestralType (next_applicable_type, decl_type))
							next_applicable_type = decl_type;
					}

					applicable_type = next_applicable_type;
					finalized = j;
					candidate_top = k;
				} while (applicable_type != null);
			}

                        //
                        // Now we actually find the best method
                        //

			method = (MethodBase) candidates [0];
			method_params = candidate_to_form != null && candidate_to_form.Contains (method);
			for (int ix = 1; ix < candidate_top; ix++){
				MethodBase candidate = (MethodBase) candidates [ix];

				if (candidate == method)
					continue;

				bool cand_params = candidate_to_form != null && candidate_to_form.Contains (candidate);

				if (BetterFunction (ec, Arguments, arg_count, 
						    candidate, cand_params,
						    method, method_params)) {
					method = candidate;
					method_params = cand_params;
				}
			}
			//
			// Now check that there are no ambiguities i.e the selected method
			// should be better than all the others
			//
			MethodBase ambiguous = null;
			for (int ix = 0; ix < candidate_top; ix++){
				MethodBase candidate = (MethodBase) candidates [ix];

                                if (candidate == method)
                                        continue;

                                bool cand_params = candidate_to_form != null && candidate_to_form.Contains (candidate);
				if (!BetterFunction (ec, Arguments, arg_count,
						     method, method_params,
						     candidate, cand_params)) {
					Report.SymbolRelatedToPreviousError (candidate);
					ambiguous = candidate;
				}
			}

			if (ambiguous != null) {
				Report.SymbolRelatedToPreviousError (method);
				Report.Error (121, loc, "The call is ambiguous between the following methods or properties: `{0}' and `{1}'",
					TypeManager.CSharpSignature (ambiguous), TypeManager.CSharpSignature (method));
				return null;
			}

			//
			// If the method is a virtual function, pick an override closer to the LHS type.
			//
			if (!me.IsBase && method.IsVirtual) {
				if (TypeManager.IsOverride (method))
					throw new InternalErrorException (
						"Should not happen.  An 'override' method took part in overload resolution: " + method);

				if (candidate_overrides != null)
					foreach (MethodBase candidate in candidate_overrides) {
						if (IsOverride (candidate, method))
							method = candidate;
					}
			}

			//
			// And now check if the arguments are all
			// compatible, perform conversions if
			// necessary etc. and return if everything is
			// all right
			//
                        if (!VerifyArgumentsCompat (ec, Arguments, arg_count, method,
                                                    method_params, null, may_fail, loc))
				return null;

			if (method == null)
				return null;

			MethodBase the_method = TypeManager.DropGenericMethodArguments (method);
#if GMCS_SOURCE
			if (the_method.IsGenericMethodDefinition &&
			    !ConstraintChecker.CheckConstraints (ec, the_method, method, loc))
				return null;
#endif

			IMethodData data = TypeManager.GetMethod (the_method);
			if (data != null)
				data.SetMemberIsUsed ();

			return method;
		}

		public static void Error_WrongNumArguments (Location loc, String name, int arg_count)
		{
			Report.Error (1501, loc, "No overload for method `{0}' takes `{1}' arguments",
				name, arg_count.ToString ());
		}

                static void Error_InvokeOnDelegate (Location loc)
                {
                        Report.Error (1533, loc,
                                      "Invoke cannot be called directly on a delegate");
                }
                        
		static void Error_InvalidArguments (Location loc, int idx, MethodBase method,
                                                    Type delegate_type, Argument a, ParameterData expected_par)
		{
			if (delegate_type == null) 
				Report.Error (1502, loc, "The best overloaded method match for `{0}' has some invalid arguments",
					      TypeManager.CSharpSignature (method));
			else
				Report.Error (1594, loc, "Delegate `{0}' has some invalid arguments",
					TypeManager.CSharpName (delegate_type));

			Parameter.Modifier mod = expected_par.ParameterModifier (idx);

			string index = (idx + 1).ToString ();
			if (mod != Parameter.Modifier.ARGLIST && mod != a.Modifier) {
				if ((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) == 0)
					Report.Error (1615, loc, "Argument `{0}' should not be passed with the `{1}' keyword",
						index, Parameter.GetModifierSignature (a.Modifier));
				else
					Report.Error (1620, loc, "Argument `{0}' must be passed with the `{1}' keyword",
						index, Parameter.GetModifierSignature (mod));
			} else {
				string p1 = Argument.FullDesc (a);
				string p2 = expected_par.ParameterDesc (idx);

				//
				// The parameter names are the same, most likely they come from different
				// assemblies.
				//
				if (p1 == p2){
					Report.Error (1503, loc,
						      "Argument {0}: Cannot conver from equally named types from different " +
						      "assemblies {0} (from {1}) and {2} (from {3})",
						      p1, a.Expr.Type.Assembly.FullName, p2,
						      expected_par.ParameterType (idx).Assembly.FullName);
				} else
					Report.Error (1503, loc, "Argument {0}: Cannot convert from `{1}' to `{2}'",
						      index, p1, p2);
				}
		}
		
		public static bool VerifyArgumentsCompat (EmitContext ec, ArrayList Arguments,
							  int arg_count, MethodBase method, 
							  bool chose_params_expanded,
							  Type delegate_type, bool may_fail,
							  Location loc)
		{
			ParameterData pd = TypeManager.GetParameterData (method);
			int j;
			for (j = 0; j < arg_count; j++) {
				Argument a = (Argument) Arguments [j];
				Expression a_expr = a.Expr;
				Type parameter_type = pd.ParameterType (j);
				Parameter.Modifier pm = pd.ParameterModifier (j);
				Parameter.Modifier am = a.Modifier;

				if (pm == Parameter.Modifier.ARGLIST) {
					if (!(a.Expr is Arglist))
						break;
					continue;
				}

				if (pm == Parameter.Modifier.PARAMS) {
					pm = Parameter.Modifier.NONE;
					if (chose_params_expanded)
						parameter_type = TypeManager.GetElementType (parameter_type);
				}

				if (pm != am)
					break;

				if (!TypeManager.IsEqual (a.Type, parameter_type)) {
					if (pm == Parameter.Modifier.OUT || pm == Parameter.Modifier.REF)
						break;

					Expression conv = Convert.ImplicitConversion (ec, a_expr, parameter_type, loc);
					if (conv == null)
						break;

					// Update the argument with the implicit conversion
					if (a_expr != conv)
						a.Expr = conv;
				}

				if (parameter_type.IsPointer && !ec.InUnsafe) {
					UnsafeError (loc);
					return false;
				}
			}

			if (j == arg_count)
				return true;

			if (!may_fail)
				Error_InvalidArguments (loc, j, method, delegate_type, (Argument) Arguments [j], pd);
			return false;
		}

		private bool resolved = false;
		public override Expression DoResolve (EmitContext ec)
		{
			if (resolved)
				return this.method == null ? null : this;

			resolved = true;
			//
			// First, resolve the expression that is used to
			// trigger the invocation
			//
			SimpleName sn = expr as SimpleName;
			if (sn != null)
				expr = sn.GetMethodGroup ();

			expr = expr.Resolve (ec, ResolveFlags.VariableOrValue | ResolveFlags.MethodGroup);
			if (expr == null)
				return null;

			if (!(expr is MethodGroupExpr)) {
				Type expr_type = expr.Type;

				if (expr_type != null){
					bool IsDelegate = TypeManager.IsDelegateType (expr_type);
					if (IsDelegate)
						return (new DelegateInvocation (
							this.expr, Arguments, loc)).Resolve (ec);
				}
			}

			if (!(expr is MethodGroupExpr)){
				expr.Error_UnexpectedKind (ResolveFlags.MethodGroup, loc);
				return null;
			}

			//
			// Next, evaluate all the expressions in the argument list
			//
			if (Arguments != null){
				foreach (Argument a in Arguments){
					if (!a.Resolve (ec, loc))
						return null;
				}
			}

			MethodGroupExpr mg = (MethodGroupExpr) expr;
			MethodBase method = OverloadResolve (ec, mg, Arguments, false, loc);

			if (method == null)
				return null;

			MethodInfo mi = method as MethodInfo;
			if (mi != null) {
				type = TypeManager.TypeToCoreType (mi.ReturnType);
				Expression iexpr = mg.InstanceExpression;
				if (mi.IsStatic) {
					if (iexpr == null || 
					    iexpr is This || iexpr is EmptyExpression ||
					    mg.IdenticalTypeName) {
						mg.InstanceExpression = null;
					} else {
						MemberExpr.error176 (loc, TypeManager.CSharpSignature (mi));
						return null;
					}
				} else {
					if (iexpr == null || iexpr is EmptyExpression) {
						SimpleName.Error_ObjectRefRequired (ec, loc, TypeManager.CSharpSignature (mi));
						return null;
					}
				}
			}

			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.Name == "Finalize") {
				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;
			}

			if ((method.Attributes & MethodAttributes.SpecialName) != 0 && IsSpecialMethodInvocation (method)) {
				return null;
			}
			
			if (mg.InstanceExpression != null)
				mg.InstanceExpression.CheckMarshalByRefAccess ();

			eclass = ExprClass.Value;
			this.method = method;
			return this;
		}

		bool IsSpecialMethodInvocation (MethodBase method)
		{
			IMethodData md = TypeManager.GetMethod (method);
			if (md != null) {
				if (!(md is AbstractPropertyEventMethod) && !(md is Operator))
					return false;
			} else {
				if (!TypeManager.IsSpecialMethod (method))
					return false;

				int args = TypeManager.GetParameterData (method).Count;
				if (method.Name.StartsWith ("get_") && args > 0)
					return false;
				else if (method.Name.StartsWith ("set_") && args > 2)
					return false;

				// TODO: check operators and events as well ?
			}

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

		// <summary>
		//   Emits the list of arguments as an array
		// </summary>
		static void EmitParams (EmitContext ec, int idx, ArrayList arguments)
		{
			ILGenerator ig = ec.ig;
			int count = arguments.Count - idx;
			Argument a = (Argument) arguments [idx];
			Type t = a.Expr.Type;

			IntConstant.EmitInt (ig, count);
			ig.Emit (OpCodes.Newarr, TypeManager.TypeToCoreType (t));

			int top = arguments.Count;
			for (int j = idx; j < top; j++){
				a = (Argument) arguments [j];
				
				ig.Emit (OpCodes.Dup);
				IntConstant.EmitInt (ig, j - idx);

				bool is_stobj, has_type_arg;
				OpCode op = ArrayAccess.GetStoreOpcode (t, out is_stobj, out has_type_arg);
				if (is_stobj)
					ig.Emit (OpCodes.Ldelema, t);

				a.Emit (ec);

				if (has_type_arg)
					ig.Emit (op, t);
				else
					ig.Emit (op);
			}
		}
		
		/// <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, MethodBase mb, ArrayList arguments, bool dup_args, LocalTemporary this_arg)
		{
			ParameterData pd = mb == null ? null : TypeManager.GetParameterData (mb);
			int top = arguments == null ? 0 : arguments.Count;
			LocalTemporary [] temps = null;
			
			if (dup_args && top != 0)
				temps = new LocalTemporary [top];

			for (int i = 0; i < top; i++){
				Argument a = (Argument) arguments [i];

				if (pd != null){
					if (pd.ParameterModifier (i) == Parameter.Modifier.PARAMS){
						//
						// Special case if we are passing the same data as the
						// params argument, do not put it in an array.
						//
						if (pd.ParameterType (i) == a.Type)
							a.Emit (ec);
						else
							EmitParams (ec, i, arguments);
						return;
					}
				}
					    
				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);
				}
			}

			if (pd != null && pd.Count > top &&
			    pd.ParameterModifier (top) == Parameter.Modifier.PARAMS){
				ILGenerator ig = ec.ig;

				IntConstant.EmitInt (ig, 0);
				ig.Emit (OpCodes.Newarr, TypeManager.GetElementType (pd.ParameterType (top)));
			}
		}

		static Type[] GetVarargsTypes (MethodBase mb, ArrayList arguments)
		{
			ParameterData pd = TypeManager.GetParameterData (mb);

			if (arguments == null)
				return new Type [0];

			Argument a = (Argument) arguments [pd.Count - 1];
			Arglist list = (Arglist) a.Expr;

			return list.ArgumentTypes;
		}

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

			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
			if (method.DeclaringType is TypeBuilder)
				return false;

			return AttributeTester.IsConditionalMethodExcluded (method);
		}

		/// <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,
					     bool is_static, Expression instance_expr,
					     MethodBase method, ArrayList Arguments, Location loc)
		{
			EmitCall (ec, is_base, is_static, 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,
					     bool is_static, 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 (!RootContext.StdLib) {
				// Replace any calls to the system's System.Array type with calls to
				// the newly created one.
				if (method == TypeManager.system_int_array_get_length)
					method = TypeManager.int_array_get_length;
				else if (method == TypeManager.system_int_array_get_rank)
					method = TypeManager.int_array_get_rank;
				else if (method == TypeManager.system_object_array_clone)
					method = TypeManager.object_array_clone;
				else if (method == TypeManager.system_int_array_get_length_int)
					method = TypeManager.int_array_get_length_int;
				else if (method == TypeManager.system_int_array_get_lower_bound_int)
					method = TypeManager.int_array_get_lower_bound_int;
				else if (method == TypeManager.system_int_array_get_upper_bound_int)
					method = TypeManager.int_array_get_upper_bound_int;
				else if (method == TypeManager.system_void_array_copyto_array_int)
					method = TypeManager.void_array_copyto_array_int;
			}

			if (!ec.IsInObsoleteScope) {
				//
				// This checks ObsoleteAttribute on the method and on the declaring type
				//
				ObsoleteAttribute oa = AttributeTester.GetMethodObsoleteAttribute (method);
				if (oa != null)
					AttributeTester.Report_ObsoleteMessage (oa, TypeManager.CSharpSignature (method), loc);

				oa = AttributeTester.GetObsoleteAttribute (method.DeclaringType);
				if (oa != null) {
					AttributeTester.Report_ObsoleteMessage (oa, method.DeclaringType.FullName, loc);
				}
			}

			if (IsMethodExcluded (method))
				return;
			
			if (!is_static){
				if (instance_expr == EmptyExpression.Null) {
					SimpleName.Error_ObjectRefRequired (ec, loc, TypeManager.CSharpSignature (method));
					return;
				}

				this_call = instance_expr is This;
				if (decl_type.IsValueType || (!this_call && instance_expr.Type.IsValueType))
					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)) {
						//
						// Special case: calls to a function declared in a 
						// reference-type with a value-type argument need
						// to have their value boxed.
						if (decl_type.IsValueType ||
						    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);
							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, method, Arguments, dup_args, this_arg);

#if GMCS_SOURCE
			if ((instance_expr != null) && (instance_expr.Type.IsGenericParameter))
				ig.Emit (OpCodes.Constrained, instance_expr.Type);
#endif

			OpCode call_op;
			if (is_static || struct_call || is_base || (this_call && !method.IsVirtual))
				call_op = OpCodes.Call;
			else
				call_op = OpCodes.Callvirt;

			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)
		{
			MethodGroupExpr mg = (MethodGroupExpr) this.expr;

			EmitCall (ec, mg.IsBase, method.IsStatic, mg.InstanceExpression, method, Arguments, loc);
		}
		
		public override void EmitStatement (EmitContext ec)
		{
			Emit (ec);

			// 
			// Pop the return value if there is one
			//
			if (method is MethodInfo){
				Type ret = ((MethodInfo)method).ReturnType;
				if (TypeManager.TypeToCoreType (ret) != TypeManager.void_type)
					ec.ig.Emit (OpCodes.Pop);
			}
		}
	}

	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 DoResolve (EmitContext ec)
		{
			//
			// First try to resolve it as a cast.
			//
			TypeExpr te = expr.ResolveAsTypeTerminal (ec, true);
			if ((te != null) && (te.eclass == ExprClass.Type)) {
				Cast cast = new Cast (te, argument, loc);
				return cast.Resolve (ec);
			}

			//
			// 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) {
				Cast cast = new Cast (new TypeExpression (expr.Type, loc), argument, loc);
				return cast.Resolve (ec);
			}

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

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

		void error201 ()
		{
			Error (201, "Only assignment, call, increment, decrement and new object " +
			       "expressions can be used as a statement");
		}

		public override ExpressionStatement ResolveStatement (EmitContext ec)
		{
			//
			// First try to resolve it as a cast.
			//
			TypeExpr te = expr.ResolveAsTypeTerminal (ec, true);
			if ((te != null) && (te.eclass == ExprClass.Type)) {
				error201 ();
				return null;
			}

			//
			// 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) || (expr.eclass == ExprClass.Type)) {
				error201 ();
				return null;
			}

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

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

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

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

	//
	// This class is used to "disable" the code generation for the
	// temporary variable when initializing value types.
	//
	class EmptyAddressOf : EmptyExpression, IMemoryLocation {
		public void AddressOf (EmitContext ec, AddressOp Mode)
		{
			// nothing
		}
	}
	
	/// <summary>
	///    Implements the new expression 
	/// </summary>
	public class New : ExpressionStatement, IMemoryLocation {
		public readonly ArrayList Arguments;

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

		MethodBase method = null;

		//
		// If set, the new expression is for a value_target, and
		// we will not leave anything on the stack.
		//
		Expression value_target;
		bool value_target_set = false;
		bool is_type_parameter = false;
		
		public New (Expression requested_type, ArrayList arguments, Location l)
		{
			RequestedType = requested_type;
			Arguments = arguments;
			loc = l;
		}

		public bool SetValueTypeVariable (Expression value)
		{
			value_target = value;
			value_target_set = true;
			if (!(value_target is IMemoryLocation)){
				Error_UnexpectedKind (null, "variable", loc);
				return false;
			}
			return true;
		}

		//
		// This function is used to disable the following code sequence for
		// value type initialization:
		//
		// AddressOf (temporary)
		// Construct/Init
		// LoadTemporary
		//
		// Instead the provide will have provided us with the address on the
		// stack to store the results.
		//
		static Expression MyEmptyExpression;
		
		public void DisableTemporaryValueType ()
		{
			if (MyEmptyExpression == null)
				MyEmptyExpression = new EmptyAddressOf ();

			//
			// To enable this, look into:
			// test-34 and test-89 and self bootstrapping.
			//
			// For instance, we can avoid a copy by using `newobj'
			// instead of Call + Push-temp on value types.
//			value_target = MyEmptyExpression;
		}


		/// <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.EnumToUnderlying (t)), t);

			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 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 == TypeManager.void_type) {
				Error_VoidInvalidInTheContext (loc);
				return null;
			}

			if (Arguments == null) {
				Expression c = Constantify (type);
				if (c != null)
					return c;
			}

			if (TypeManager.IsDelegateType (type)) {
				RequestedType = (new NewDelegate (type, Arguments, loc)).Resolve (ec);
				if (RequestedType != null)
					if (!(RequestedType is DelegateCreation))
						throw new Exception ("NewDelegate.Resolve returned a non NewDelegate: " + RequestedType.GetType ());
				return RequestedType;
			}

#if GMCS_SOURCE
			if (type.IsGenericParameter) {
				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;
				}

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

			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){
				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 = type.IsValueType;
			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 (ml == null)
				return null;

			MethodGroupExpr mg = ml as MethodGroupExpr;

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

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

			method = Invocation.OverloadResolve (ec, mg, Arguments, false, loc);
			if (method == null) {
				if (almostMatchedMembers.Count != 0)
					MemberLookupFailed (ec.ContainerType, type, type, ".ctor", null, true, loc);
				return null;
			}

			return this;
		}

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

			ig.Emit (OpCodes.Ldtoken, type);
			ig.Emit (OpCodes.Call, TypeManager.system_type_get_type_from_handle);
			ig.Emit (OpCodes.Call, TypeManager.activator_create_instance);
			ig.Emit (OpCodes.Unbox_Any, type);
			return true;
#else
			throw new InternalErrorException ();
#endif
		}

		//
		// This DoEmit 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)
		//
		// You can control whether a value is required on the stack by passing
		// need_value_on_stack.  The code *might* leave a value on the stack
		// so it must be popped manually
		//
		// 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
		//
		bool DoEmit (EmitContext ec, bool need_value_on_stack)
		{
			bool is_value_type = TypeManager.IsValueType (type);
			ILGenerator ig = ec.ig;

			if (is_value_type){
				IMemoryLocation ml;

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

				ml = (IMemoryLocation) value_target;
				ml.AddressOf (ec, AddressOp.Store);
			}

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

			if (is_value_type){
				if (method == null)
					ig.Emit (OpCodes.Initobj, type);
				else 
					ig.Emit (OpCodes.Call, (ConstructorInfo) method);
                                if (need_value_on_stack){
                                        value_target.Emit (ec);
                                        return true;
                                }
                                return false;
			} else {
				ig.Emit (OpCodes.Newobj, (ConstructorInfo) method);
				return true;
			}
		}

		public override void Emit (EmitContext ec)
		{
			if (is_type_parameter)
				DoEmitTypeParameter (ec);
			else
				DoEmit (ec, true);
		}
		
		public override void EmitStatement (EmitContext ec)
		{
			if (is_type_parameter)
				throw new InvalidOperationException ();

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

		public void AddressOf (EmitContext ec, AddressOp Mode)
		{
			if (is_type_parameter)
				throw new InvalidOperationException ();

			if (!type.IsValueType){
				//
				// 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");
			}

			if (!value_target_set)
				value_target = new LocalTemporary (type);
					
			IMemoryLocation ml = (IMemoryLocation) value_target;
			ml.AddressOf (ec, AddressOp.Store);
			if (method != null)
				Invocation.EmitArguments (ec, method, Arguments, false, null);

			if (method == null)
				ec.ig.Emit (OpCodes.Initobj, type);
			else 
				ec.ig.Emit (OpCodes.Call, (ConstructorInfo) method);
			
			((IMemoryLocation) value_target).AddressOf (ec, Mode);
		}
	}

	/// <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 {
		Expression requested_base_type;
		ArrayList initializers;

		//
		// The list of Argument types.
		// This is used to construct the `newarray' or constructor signature
		//
		ArrayList arguments;

		//
		// Method used to create the array object.
		//
		MethodBase new_method = null;
		
		Type array_element_type;
		Type underlying_type;
		bool is_one_dimensional = false;
		bool is_builtin_type = false;
		bool expect_initializers = false;
		int num_arguments = 0;
		int dimensions = 0;
		string rank;

		ArrayList array_data;

		IDictionary bounds;

		// The number of constants in array initializers
		int const_initializers_count;
		
		public ArrayCreation (Expression 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 ();

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

		public ArrayCreation (Expression 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 Expression FormArrayType (Expression base_type, int idx_count, string rank)
		{
			StringBuilder sb = new StringBuilder (rank);
			
			sb.Append ("[");
			for (int i = 1; i < idx_count; i++)
				sb.Append (",");
			
			sb.Append ("]");

			return new ComposedCast (base_type, sb.ToString (), loc);
		}

		void Error_IncorrectArrayInitializer ()
		{
			Error (178, "Invalid rank specifier: expected `,' or `]'");
		}
		
		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 (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 ();
					return false;
				}
				
				bounds [idx] = value;
			}

			int child_bounds = -1;
			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 ();
						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 ();
						return false;
					}
					
					Expression tmp = (Expression) o;
					tmp = tmp.Resolve (ec);
					if (tmp == null)
						return false;

					Expression conv = Convert.ImplicitConversionRequired (
						ec, tmp, underlying_type, loc);
					
					if (conv == null) 
						return false;

					// Initializers with the default values can be ignored
					Constant c = tmp as Constant;
					if (c != null) {
						if (c.IsDefaultInitializer (array_element_type)) {
							conv = null;
						}
						else {
							++const_initializers_count;
						}
					} else {
						// Used to invalidate static initializer
						const_initializers_count = int.MinValue;
					}
					
					array_data.Add (conv);
				}
			}

			return true;
		}
		
		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;
				}
			}

		}
		
		bool ResolveInitializers (EmitContext ec)
		{
			if (initializers == null) {
				return !expect_initializers;
			}
			
			if (underlying_type == null)
				return false;
			
			//
			// 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 ();
				
			if (arguments.Count != dimensions) {
				Error_IncorrectArrayInitializer ();
				return false;
			}

			return true;
		}

		//
		// Creates the type of the array
		//
		bool LookupType (EmitContext ec)
		{
			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;
			underlying_type = TypeManager.GetElementType (type);
			dimensions = type.GetArrayRank ();

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

			if (!LookupType (ec))
				return null;
			
			array_element_type = TypeManager.GetElementType (type);
			if (array_element_type.IsAbstract && array_element_type.IsSealed) {
				Report.Error (719, loc, "`{0}': array elements cannot be of static type", TypeManager.CSharpName (array_element_type));
				return null;
			}

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

			int arg_count;
			if (arguments == null)
				arg_count = 0;
			else {
				arg_count = arguments.Count;
				foreach (Argument a in arguments){
					if (!a.Resolve (ec, loc))
						return null;

					Expression real_arg = ExpressionToArrayArgument (ec, a.Expr, loc);
					if (real_arg == null)
						return null;

					a.Expr = real_arg;
				}
			}
			
			if (arg_count == 1) {
				is_one_dimensional = true;
				eclass = ExprClass.Value;
				return this;
			}

			is_builtin_type = TypeManager.IsBuiltinType (type);

			if (is_builtin_type) {
				Expression ml;
				
				ml = MemberLookup (ec.ContainerType, type, ".ctor", MemberTypes.Constructor,
						   AllBindingFlags, loc);
				
				if (!(ml is MethodGroupExpr)) {
					ml.Error_UnexpectedKind (ec.DeclContainer, "method group", loc);
					return null;
				}
				
				if (ml == null) {
					Error (-6, "New invocation: Can not find a constructor for " +
						      "this argument list");
					return null;
				}
				
				new_method = Invocation.OverloadResolve (
					ec, (MethodGroupExpr) ml, arguments, false, loc);

				if (new_method == null) {
					Error (-6, "New invocation: Can not find a constructor for " +
						      "this argument list");
					return null;
				}
				
				eclass = ExprClass.Value;
				return this;
			} else {
				ModuleBuilder mb = CodeGen.Module.Builder;
				ArrayList args = new ArrayList ();
				
				if (arguments != null) {
					for (int i = 0; i < arg_count; i++)
						args.Add (TypeManager.int32_type);
				}
				
				Type [] arg_types = null;

				if (args.Count > 0)
					arg_types = new Type [args.Count];
				
				args.CopyTo (arg_types, 0);
				
				new_method = mb.GetArrayMethod (type, ".ctor", CallingConventions.HasThis, null,
							    arg_types);

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

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

			if (underlying_type.IsEnum)
				underlying_type = TypeManager.EnumToUnderlying (underlying_type);
			
			factor = GetTypeSize (underlying_type);
			if (factor == 0)
				throw new Exception ("unrecognized type in MakeByteBlob: " + underlying_type);

			data = new byte [(count * factor + 4) & ~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 (underlying_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 (underlying_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 (underlying_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];
					}
				} else if (underlying_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];
					}
				} else if (underlying_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 (underlying_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 (underlying_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 (underlying_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 (underlying_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 (underlying_type == TypeManager.sbyte_type) {
					if (!(v is Expression)){
						sbyte val = (sbyte) v;
						data [idx] = (byte) val;
					}
				} else if (underlying_type == TypeManager.byte_type) {
					if (!(v is Expression)){
						byte val = (byte) v;
						data [idx] = (byte) val;
					}
				} else if (underlying_type == TypeManager.bool_type) {
					if (!(v is Expression)){
						bool val = (bool) v;
						data [idx] = (byte) (val ? 1 : 0);
					}
				} else if (underlying_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: " + underlying_type);

                                idx += factor;
			}

			return data;
		}

		//
		// Emits the initializers for the array
		//
		void EmitStaticInitializers (EmitContext ec)
		{
			//
			// 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)
		{
			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 = CodeGen.Module.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];

				if (e != null) {
					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) && etype.IsValueType &&
					    (!TypeManager.IsBuiltinOrEnum (etype) ||
					     etype == TypeManager.decimal_type)) {
						if (e is New){
							New n = (New) e;

							//
							// Let new know that we are providing
							// the address where to store the results
							//
							n.DisableTemporaryValueType ();
						}

						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;
				}
			}
		}

		void EmitArrayArguments (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			foreach (Argument a in arguments) {
				Type atype = a.Type;
				a.Emit (ec);

				if (atype == TypeManager.uint64_type)
					ig.Emit (OpCodes.Conv_Ovf_U4);
				else if (atype == TypeManager.int64_type)
					ig.Emit (OpCodes.Conv_Ovf_I4);
			}
		}
		
		public override void Emit (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			EmitArrayArguments (ec);
			if (is_one_dimensional)
				ig.Emit (OpCodes.Newarr, array_element_type);
			else {
				if (is_builtin_type) 
					ig.Emit (OpCodes.Newobj, (ConstructorInfo) new_method);
				else 
					ig.Emit (OpCodes.Newobj, (MethodInfo) new_method);
			}
			
			if (initializers == null)
				return;

			// This is a treshold for static initializers
			// I tried to make more accurate but it seems to me that Array.Initialize is
			// always slower (managed -> unmanaged switch?)
			const int max_automatic_initializers = 200;

			if (const_initializers_count > max_automatic_initializers && TypeManager.IsPrimitiveType (array_element_type)) {
				EmitStaticInitializers (ec);
				return;
			}
				
			EmitDynamicInitializers (ec);
		}

		public override bool GetAttributableValue (Type valueType, out object value)
		{
			if (!is_one_dimensional){
//				Report.Error (-211, Location, "attribute can not encode multi-dimensional arrays");
				return base.GetAttributableValue (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 (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 (array_element_type, out element_value)) {
					value = null;
					return false;
				}
				ret.SetValue (element_value, i);
			}
			value = ret;
			return true;
		}
	}
	
	public sealed class CompilerGeneratedThis : This
	{
		public static This Instance = new CompilerGeneratedThis ();

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

		public override Expression DoResolve (EmitContext ec)
		{
			eclass = ExprClass.Variable;
			type = ec.ContainerType;
			variable = new SimpleThis (type);
			return this;
		}
	}
	
	/// <summary>
	///   Represents the `this' construct
	/// </summary>

	public class This : VariableReference, IVariable
	{
		Block block;
		VariableInfo variable_info;
		protected Variable variable;
		bool is_struct;

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

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

		public VariableInfo VariableInfo {
			get { return variable_info; }
		}

		public bool VerifyFixed ()
		{
			return !TypeManager.IsValueType (Type);
		}

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

		public override Variable Variable {
			get { return variable; }
		}

		public bool ResolveBase (EmitContext ec)
		{
			eclass = ExprClass.Variable;

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

			is_struct = ec.TypeContainer is Struct;

			if (ec.IsStatic) {
				Error (26, "Keyword `this' is not valid in a static property, " +
				       "static method, or static field initializer");
				return false;
			}

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

				AnonymousContainer am = ec.CurrentAnonymousMethod;
				if (is_struct && (am != null) && !am.IsIterator) {
					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.");
					return false;
				}

				RootScopeInfo host = block.Toplevel.RootScope;
				if ((host != null) && !ec.IsConstructor &&
				    (!is_struct || host.IsIterator)) {
					variable = host.CaptureThis ();
					type = variable.Type;
					is_struct = false;
				}
			}

			if (variable == null)
				variable = new SimpleThis (type);
			
			return true;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			if (!ResolveBase (ec))
				return null;

			if ((variable_info != null) && !(type.IsValueType && 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);
				return this;
			}

			if (ec.IsFieldInitializer) {
				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){
				Error (1604, "Cannot assign to 'this' because it is read-only");
				return null;
			}

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

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

			return block == t.block;
		}

		protected class SimpleThis : Variable
		{
			Type type;

			public SimpleThis (Type type)
			{
				this.type = type;
			}

			public override Type Type {
				get { return type; }
			}

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

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

			public override void EmitInstance (EmitContext ec)
			{
				// Do nothing.
			}

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

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

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

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

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

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

			return this;
		}

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

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

		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 DoResolve (EmitContext ec)
		{
			eclass = ExprClass.Variable;
			type = TypeManager.runtime_argument_handle_type;

			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);
		}
	}

	//
	// This produces the value that renders an instance, used by the iterators code
	//
	public class ProxyInstance : Expression, IMemoryLocation  {
		public override Expression DoResolve (EmitContext ec)
		{
			eclass = ExprClass.Variable;
			type = ec.ContainerType;
			return this;
		}
		
		public override void Emit (EmitContext ec)
		{
			ec.ig.Emit (OpCodes.Ldarg_0);

		}
		
		public void AddressOf (EmitContext ec, AddressOp mode)
		{
			ec.ig.Emit (OpCodes.Ldarg_0);
		}
	}

	/// <summary>
	///   Implements the typeof operator
	/// </summary>
	public class TypeOf : Expression {
		readonly Expression QueriedType;
		protected Type typearg;
		
		public TypeOf (Expression queried_type, Location l)
		{
			QueriedType = queried_type;
			loc = l;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			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;
			// 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 (Type valueType, out object value)
		{
			if (TypeManager.ContainsGenericParameters (typearg)) {
				Report.SymbolRelatedToPreviousError(typearg);
				Report.Error(416, loc, "`{0}': an attribute argument cannot use type parameters",
					     TypeManager.CSharpName(typearg));
				value = null;
				return false;
			}

			if (valueType == TypeManager.object_type) {
				value = (object)typearg;
				return true;
			}
			value = typearg;
			return true;
		}

		public Type TypeArgument
		{
			get
			{
				return typearg;
			}
		}
	}

	/// <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;
			// See description in TypeOf.
			eclass = ExprClass.Value;
			return this;
		}
	}

	/// <summary>
	///   Implements the sizeof expression
	/// </summary>
	public class SizeOf : Expression {
		public Expression QueriedType;
		Type type_queried;
		
		public SizeOf (Expression queried_type, Location l)
		{
			this.QueriedType = queried_type;
			loc = l;
		}

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

#if GMCS_SOURCE
			if (texpr is TypeParameterExpr){
				((TypeParameterExpr)texpr).Error_CannotUseAsUnmanagedType (loc);
				return null;
			}
#endif

			type_queried = texpr.Type;
			if (type_queried.IsEnum)
				type_queried = TypeManager.EnumToUnderlying (type_queried);

			if (type_queried == TypeManager.void_type) {
				Expression.Error_VoidInvalidInTheContext (loc);
				return null;
			}

			int size_of = GetTypeSize (type_queried);
			if (size_of > 0) {
				return new IntConstant (size_of, loc);
			}

			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));
				return null;
			}

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

	/// <summary>
	///   Implements the qualified-alias-member (::) expression.
	/// </summary>
	public class QualifiedAliasMember : Expression
	{
		string alias, identifier;

		public QualifiedAliasMember (string alias, string identifier, Location l)
		{
			this.alias = alias;
			this.identifier = identifier;
			loc = l;
		}

		public override FullNamedExpression ResolveAsTypeStep (IResolveContext ec, bool silent)
		{
			if (alias == "global")
				return new MemberAccess (RootNamespace.Global, identifier, loc).ResolveAsTypeStep (ec, silent);

			int errors = Report.Errors;
			FullNamedExpression fne = ec.DeclContainer.NamespaceEntry.LookupAlias (alias);
			if (fne == null) {
				if (errors == Report.Errors)
					Report.Error (432, loc, "Alias `{0}' not found", alias);
				return null;
			}
			if (fne.eclass != ExprClass.Namespace) {
				if (!silent)
					Report.Error (431, loc, "`{0}' cannot be used with '::' since it denotes a type", alias);
				return null;
			}
			return new MemberAccess (fne, identifier).ResolveAsTypeStep (ec, silent);
		}

		public override Expression DoResolve (EmitContext ec)
		{
			FullNamedExpression fne;
			if (alias == "global") {
				fne = RootNamespace.Global;
			} else {
				int errors = Report.Errors;
				fne = ec.DeclContainer.NamespaceEntry.LookupAlias (alias);
				if (fne == null) {
					if (errors == Report.Errors)
						Report.Error (432, loc, "Alias `{0}' not found", alias);
					return null;
				}
			}

			Expression retval = new MemberAccess (fne, identifier).DoResolve (ec);
			if (retval == null)
				return null;

			if (!(retval is FullNamedExpression)) {
				Report.Error (687, loc, "The expression `{0}::{1}' did not resolve to a namespace or a type", alias, identifier);
				return null;
			}

			// We defer this check till the end to match the behaviour of CSC
			if (fne.eclass != ExprClass.Namespace) {
				Report.Error (431, loc, "`{0}' cannot be used with '::' since it denotes a type", alias);
				return null;
			}
			return retval;
		}

		public override void Emit (EmitContext ec)
		{
			throw new InternalErrorException ("QualifiedAliasMember found in resolved tree");
		}


		public override string ToString ()
		{
			return alias + "::" + identifier;
		}

		public override string GetSignatureForError ()
		{
			return ToString ();
		}
	}

	/// <summary>
	///   Implements the member access expression
	/// </summary>
	public class MemberAccess : Expression {
		public readonly string Identifier;
		Expression expr;

		public MemberAccess (Expression expr, string id)
			: this (expr, id, expr.Location)
		{
		}

		public MemberAccess (Expression expr, string identifier, Location loc)
		{
			this.expr = expr;
			Identifier = identifier;
			this.loc = loc;
		}

		public MemberAccess (Expression expr, string identifier, TypeArguments args, Location loc)
			: this (expr, identifier, loc)
		{
			this.args = args;
		}

		TypeArguments args;

		public Expression Expr {
			get { return expr; }
		}

		protected string LookupIdentifier {
			get { return MemberName.MakeName (Identifier, args); }
		}

		// TODO: this method has very poor performace for Enum fields and
		// probably for other constants as well
		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 new_expr = expr.Resolve (ec,
				ResolveFlags.VariableOrValue | ResolveFlags.Type |
				ResolveFlags.Intermediate | ResolveFlags.DisableStructFlowAnalysis);

			if (new_expr == null)
				return null;

			if (new_expr is Namespace) {
				Namespace ns = (Namespace) new_expr;
				FullNamedExpression retval = ns.Lookup (ec.DeclContainer, LookupIdentifier, loc);
#if GMCS_SOURCE
				if ((retval != null) && (args != null))
					retval = new ConstructedType (retval, args, loc).ResolveAsTypeStep (ec, false);
#endif

				if (retval == null)
					ns.Error_NamespaceDoesNotExist (ec.DeclContainer, loc, Identifier);
				return retval;
			}

			Type expr_type = new_expr.Type;
			if (expr_type.IsPointer || expr_type == TypeManager.void_type || new_expr is NullLiteral){
				Unary.Error_OperatorCannotBeApplied (loc, ".", expr_type);
				return null;
			}
			if (expr_type == TypeManager.anonymous_method_type){
				Unary.Error_OperatorCannotBeApplied (loc, ".", "anonymous method");
				return null;
			}

			Constant c = new_expr as Constant;
			if (c != null && c.GetValue () == null) {
				Report.Warning (1720, 1, loc, "Expression will always cause a `{0}'",
					"System.NullReferenceException");
			}

			Expression member_lookup;
			member_lookup = MemberLookup (
				ec.ContainerType, expr_type, expr_type, Identifier, loc);
#if GMCS_SOURCE
			if ((member_lookup == null) && (args != null)) {
				member_lookup = MemberLookup (
					ec.ContainerType, expr_type, expr_type, LookupIdentifier, loc);
			}
#endif
			if (member_lookup == null) {
				MemberLookupFailed (
					ec.ContainerType, expr_type, expr_type, Identifier, null, true, loc);
				return null;
			}

			TypeExpr texpr = member_lookup as TypeExpr;
			if (texpr != null) {
				if (!(new_expr is TypeExpr) && 
				    (original == null || !original.IdenticalNameAndTypeName (ec, new_expr, loc))) {
					Report.Error (572, loc, "`{0}': cannot reference a type through an expression; try `{1}' instead",
						Identifier, member_lookup.GetSignatureForError ());
					return null;
				}

				if (!texpr.CheckAccessLevel (ec.DeclContainer)) {
					Report.SymbolRelatedToPreviousError (member_lookup.Type);
					ErrorIsInaccesible (loc, TypeManager.CSharpName (member_lookup.Type));
					return null;
				}

#if GMCS_SOURCE
				ConstructedType ct = new_expr as ConstructedType;
				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 ConstructedType (
						member_lookup.Type, ct.TypeArguments, loc);

					return ct.ResolveAsTypeStep (ec, false);
				}
#endif
				return member_lookup;
			}

			MemberExpr me = (MemberExpr) member_lookup;
			member_lookup = me.ResolveMemberAccess (ec, new_expr, loc, original);
			if (member_lookup == null)
				return null;

			if (args != null) {
				MethodGroupExpr mg = member_lookup as MethodGroupExpr;
				if (mg == null)
					throw new InternalErrorException ();

				return mg.ResolveGeneric (ec, args);
			}

			if (original != null && !TypeManager.IsValueType (expr_type)) {
				me = member_lookup as MemberExpr;
				if (me != null && me.IsInstance) {
					LocalVariableReference var = new_expr 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 member_lookup.DoResolveLValue (ec, right_side);
			else
				return member_lookup.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 new_expr = expr.ResolveAsTypeStep (rc, silent);

			if (new_expr == null)
				return null;

			if (new_expr is Namespace) {
				Namespace ns = (Namespace) new_expr;
				FullNamedExpression retval = ns.Lookup (rc.DeclContainer, LookupIdentifier, loc);
#if GMCS_SOURCE
				if ((retval != null) && (args != null))
					retval = new ConstructedType (retval, args, loc).ResolveAsTypeStep (rc, false);
#endif
				if (!silent && retval == null)
					ns.Error_NamespaceDoesNotExist (rc.DeclContainer, loc, LookupIdentifier);
				return retval;
			}

			TypeExpr tnew_expr = new_expr.ResolveAsTypeTerminal (rc, false);
			if (tnew_expr == null)
				return null;

			Type expr_type = tnew_expr.Type;

			if (expr_type.IsPointer){
				Error (23, "The `.' operator can not be applied to pointer operands (" +
				       TypeManager.CSharpName (expr_type) + ")");
				return null;
			}

			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;

		                member_lookup = MemberLookup(
                		    rc.DeclContainer.TypeBuilder, expr_type, expr_type, LookupIdentifier,
                    			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}'",
						      Identifier, new_expr.GetSignatureForError ());
				} else {
    				// TODO: Report.SymbolRelatedToPreviousError
				    member_lookup.Error_UnexpectedKind (null, "type", loc);
    				}
				return null;
			}

			TypeExpr texpr = member_lookup.ResolveAsTypeTerminal (rc, false);
			if (texpr == null)
				return null;

#if GMCS_SOURCE
			TypeArguments the_args = args;
			if (TypeManager.HasGenericArguments (expr_type)) {
				Type[] decl_args = TypeManager.GetTypeArguments (expr_type);

				TypeArguments new_args = new TypeArguments (loc);
				foreach (Type decl in decl_args)
					new_args.Add (new TypeExpression (decl, loc));

				if (args != null)
					new_args.Add (args);

				the_args = new_args;
			}

			if (the_args != null) {
				ConstructedType ctype = new ConstructedType (texpr.Type, the_args, loc);
				return ctype.ResolveAsTypeStep (rc, false);
			}
#endif

			return texpr;
		}

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

		public override string ToString ()
		{
			return expr + "." + MemberName.MakeName (Identifier, args);
		}

		public override string GetSignatureForError ()
		{
			return expr.GetSignatureForError () + "." + Identifier;
		}
	}

	/// <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 DoResolve (EmitContext ec)
		{
			using (ec.With (EmitContext.Flags.AllCheckStateFlags, true))
				Expr = Expr.Resolve (ec);
			
			if (Expr == null)
				return null;

			if (Expr is Constant)
				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 onTrue)
		{
			using (ec.With (EmitContext.Flags.AllCheckStateFlags, true))
				Expr.EmitBranchable (ec, target, onTrue);
		}
	}

	/// <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 DoResolve (EmitContext ec)
		{
			using (ec.With (EmitContext.Flags.AllCheckStateFlags, false))
				Expr = Expr.Resolve (ec);

			if (Expr == null)
				return null;

			if (Expr is Constant)
				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 onTrue)
		{
			using (ec.With (EmitContext.Flags.AllCheckStateFlags, false))
				Expr.EmitBranchable (ec, target, onTrue);
		}
	}

	/// <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 ();
			foreach (Expression tmp in e_list)
				Arguments.Add (new Argument (tmp, Argument.AType.Expression));
			
		}

		bool CommonResolve (EmitContext ec)
		{
			Expr = Expr.Resolve (ec);

			if (Expr == null) 
				return false;

			if (Arguments == null)
				return false;

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

			return true;
		}

		Expression MakePointerAccess (EmitContext ec, Type t)
		{
			if (t == TypeManager.void_ptr_type){
				Error (242, "The array index operation is not valid on void pointers");
				return null;
			}
			if (Arguments.Count != 1){
				Error (196, "A pointer must be indexed by only one value");
				return null;
			}
			Expression p;

			p = new PointerArithmetic (true, 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, Expr.Type);

			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 t = Expr.Type;
			if (t.IsArray)
				return (new ArrayAccess (this, loc)).DoResolveLValue (ec, right_side);

			if (t.IsPointer)
				return MakePointerAccess (ec, Expr.Type);

			FieldExpr fe = Expr as FieldExpr;
			if (fe != null) {
				IFixedBuffer ff = AttributeTester.GetFixedBuffer (fe.FieldInfo);
				if (ff != null) {
					if (!(fe.InstanceExpression is LocalVariableReference) && 
						!(fe.InstanceExpression is This)) {
						Report.Error (1708, loc, "Fixed size buffers can only be accessed through locals or fields");
						return null;
					}
					if (!ec.InFixedInitializer && ec.ContainerType.IsValueType) {
						Error (1666, "You cannot use fixed size buffers contained in unfixed expressions. Try using the fixed statement");
						return null;
					}
					return MakePointerAccess (ec, ff.ElementType);
				}
			}
			return (new IndexerAccess (this, loc)).DoResolveLValue (ec, right_side);
		}
		
		public override void Emit (EmitContext ec)
		{
			throw new Exception ("Should never be reached");
		}
	}

	/// <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;
			eclass = ExprClass.Variable;
			loc = l;
		}

		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

			Type t = ea.Expr.Type;
			if (t.GetArrayRank () != ea.Arguments.Count){
				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){
				Type argtype = a.Type;

				if (argtype == TypeManager.int32_type ||
				    argtype == TypeManager.uint32_type ||
				    argtype == TypeManager.int64_type ||
				    argtype == TypeManager.uint64_type) {
					Constant c = a.Expr as Constant;
					if (c != null && c.IsNegative) {
						Report.Warning (251, 2, ea.Location, "Indexing an array with a negative index (array indices always start at zero)");
					}
					continue;
				}

				//
				// Mhm.  This is strage, because the Argument.Type is not the same as
				// Argument.Expr.Type: the value changes depending on the ref/out setting.
				//
				// Wonder if I will run into trouble for this.
				//
				a.Expr = ExpressionToArrayArgument (ec, a.Expr, ea.Location);
				if (a.Expr == null)
					return null;
			}
			
			eclass = ExprClass.Variable;

			return this;
		}

		/// <summary>
		///    Emits the right opcode to load an object of Type `t'
		///    from an array of T
		/// </summary>
		static public void EmitLoadOpcode (ILGenerator ig, Type type)
		{
			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.EnumToUnderlying (type));
			} else if (type.IsValueType){
				ig.Emit (OpCodes.Ldelema, type);
				ig.Emit (OpCodes.Ldobj, type);
#if GMCS_SOURCE
			} else if (type.IsGenericParameter) {
#if MS_COMPATIBLE
				ig.Emit (OpCodes.Ldelem, type);
#else
				ig.Emit (OpCodes.Ldelem_Any, type);
#endif
#endif
			} else if (type.IsPointer)
				ig.Emit (OpCodes.Ldelem_I);
			else
				ig.Emit (OpCodes.Ldelem_Ref);
		}

		/// <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.EnumToUnderlying (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 (t.IsValueType) {
				has_type_arg = true;
				is_stobj = true;
				return OpCodes.Stobj;
#if GMCS_SOURCE
			} else if (t.IsGenericParameter) {
				has_type_arg = true;
#if MS_COMPATIBLE
				return OpCodes.Stelem;
#else
				return OpCodes.Stelem_Any;
#endif
#endif

			} else if (t.IsPointer)
				return OpCodes.Stelem_I;
			else
				return OpCodes.Stelem_Ref;
		}

		MethodInfo FetchGetMethod ()
		{
			ModuleBuilder mb = CodeGen.Module.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 = CodeGen.Module.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.
		//
		// If we have been requested to cache the values (cached_locations array
		// initialized), then load the arguments the first time and store them
		// in locals.  otherwise load from local variables.
		//
		void LoadArrayAndArguments (EmitContext ec)
		{
			ILGenerator ig = ec.ig;
			
			ea.Expr.Emit (ec);
			foreach (Argument a in ea.Arguments){
				Type argtype = a.Expr.Type;
				
				a.Expr.Emit (ec);
				
				if (argtype == TypeManager.int64_type)
					ig.Emit (OpCodes.Conv_Ovf_I);
				else if (argtype == TypeManager.uint64_type)
					ig.Emit (OpCodes.Conv_Ovf_I_Un);
			}
		}

		public void Emit (EmitContext ec, bool leave_copy)
		{
			int rank = ea.Expr.Type.GetArrayRank ();
			ILGenerator ig = ec.ig;

			if (!prepared) {
				LoadArrayAndArguments (ec);
				
				if (rank == 1)
					EmitLoadOpcode (ig, type);
				else {
					MethodInfo method;
					
					method = FetchGetMethod ();
					ig.Emit (OpCodes.Call, method);
				}
			} else
				LoadFromPtr (ec.ig, this.type);
			
			if (leave_copy) {
				ec.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 (prepare_for_load) {
				AddressOf (ec, AddressOp.LoadStore);
				ec.ig.Emit (OpCodes.Dup);
				source.Emit (ec);
				if (leave_copy) {
					ec.ig.Emit (OpCodes.Dup);
					temp = new LocalTemporary (this.type);
					temp.Store (ec);
				}
				StoreFromPtr (ec.ig, t);
				
				if (temp != null) {
					temp.Emit (ec);
					temp.Release (ec);
				}
				
				return;
			}
			
			LoadArrayAndArguments (ec);

			if (rank == 1) {
				bool is_stobj, has_type_arg;
				OpCode op = GetStoreOpcode (t, out is_stobj, out has_type_arg);
				//
				// 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 (is_stobj)
					ig.Emit (OpCodes.Stobj, t);
				else if (has_type_arg)
					ig.Emit (op, t);
				else
					ig.Emit (op);
			} else {
				ModuleBuilder mb = CodeGen.Module.Builder;
				int arg_count = ea.Arguments.Count;
				Type [] args = new Type [arg_count + 1];
				MethodInfo set;
				
				source.Emit (ec);
				if (leave_copy) {
					ec.ig.Emit (OpCodes.Dup);
					temp = new LocalTemporary (this.type);
					temp.Store (ec);
				}
				
				for (int i = 0; i < arg_count; i++){
					//args [i++] = a.Type;
					args [i] = TypeManager.int32_type;
				}

				args [arg_count] = type;
				
				set = mb.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 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 void EmitGetLength (EmitContext ec, int dim)
		{
			int rank = ea.Expr.Type.GetArrayRank ();
			ILGenerator ig = ec.ig;

			ea.Expr.Emit (ec);
			if (rank == 1) {
				ig.Emit (OpCodes.Ldlen);
				ig.Emit (OpCodes.Conv_I4);
			} else {
				IntLiteral.EmitInt (ig, dim);
				ig.Emit (OpCodes.Callvirt, TypeManager.int_getlength_int);
			}
		}
	}
	
	class Indexers {
		// note that the ArrayList itself in mutable.  We just can't assign to 'Properties' again.
		public readonly ArrayList Properties;
		static Indexers empty;

		public struct Indexer {
			public readonly PropertyInfo PropertyInfo;
			public readonly MethodInfo Getter, Setter;

			public Indexer (PropertyInfo property_info, MethodInfo get, MethodInfo set)
			{
				this.PropertyInfo = property_info;
				this.Getter = get;
				this.Setter = set;
			}
		}

		static Indexers ()
		{
			empty = new Indexers (null);
		}

		Indexers (ArrayList array)
		{
			Properties = array;
		}

		static void Append (ref Indexers ix, Type caller_type, MemberInfo [] mi)
		{
			bool dummy;
			if (mi == null)
				return;
			foreach (PropertyInfo property in mi){
				MethodInfo get, set;
				
				get = property.GetGetMethod (true);
				set = property.GetSetMethod (true);
				if (get != null && !Expression.IsAccessorAccessible (caller_type, get, out dummy))
					get = null;
				if (set != null && !Expression.IsAccessorAccessible (caller_type, set, out dummy))
					set = null;
				if (get != null || set != null) {
					if (ix == empty)
						ix = new Indexers (new ArrayList ());
					ix.Properties.Add (new Indexer (property, get, set));
				}
			}
		}

		static private 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);
		}
		
		static public Indexers GetIndexersForType (Type caller_type, Type lookup_type) 
		{
			Indexers ix = empty;

#if GMCS_SOURCE
			if (lookup_type.IsGenericParameter) {
				GenericConstraints gc = TypeManager.GetTypeParameterConstraints (lookup_type);
				if (gc == null)
					return empty;

				if (gc.HasClassConstraint)
					Append (ref ix, caller_type, GetIndexersForTypeOrInterface (caller_type, gc.ClassConstraint));

				Type[] ifaces = gc.InterfaceConstraints;
				foreach (Type itype in ifaces)
					Append (ref ix, caller_type, GetIndexersForTypeOrInterface (caller_type, itype));

				return ix;
			}
#endif

			Type copy = lookup_type;
			while (copy != TypeManager.object_type && copy != null){
				Append (ref ix, 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)
						Append (ref ix, caller_type, GetIndexersForTypeOrInterface (caller_type, itype));
				}
			}

			return ix;
		}
	}

	/// <summary>
	///   Expressions that represent an indexer call.
	/// </summary>
	public class IndexerAccess : Expression, IAssignMethod {
		//
		// Points to our "data" repository
		//
		MethodInfo get, set;
		ArrayList set_arguments;
		bool is_base_indexer;

		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;
		}

		protected virtual bool CommonResolve (EmitContext ec)
		{
			indexer_type = instance_expr.Type;
			current_type = ec.ContainerType;

			return true;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			if (!CommonResolve (ec))
				return null;

			//
			// Step 1: Query for all `Item' *properties*.  Notice
			// that the actual methods are pointed from here.
			//
			// This is a group of properties, piles of them.  

			ArrayList AllGetters = null;

			Indexers ilist = Indexers.GetIndexersForType (current_type, indexer_type);
			if (ilist.Properties != null) {
				AllGetters = new ArrayList(ilist.Properties.Count);
				foreach (Indexers.Indexer ix in ilist.Properties) {
					if (ix.Getter != null)
						AllGetters.Add (ix.Getter);
				}
			}

			if (AllGetters == null) {
				Report.Error (21, loc, "Cannot apply indexing with [] to an expression of type `{0}'",
					TypeManager.CSharpName (indexer_type));
				return null;
			}

			if (AllGetters.Count == 0) {
				// FIXME: we cannot simply select first one as the error message is missleading when
				// multiple indexers exist
				Indexers.Indexer first_indexer = (Indexers.Indexer)ilist.Properties[ilist.Properties.Count - 1];
				Report.Error (154, loc, "The property or indexer `{0}' cannot be used in this context because it lacks the `get' accessor",
					TypeManager.GetFullNameSignature (first_indexer.PropertyInfo));
				return null;
			}

			get = (MethodInfo)Invocation.OverloadResolve (ec, new MethodGroupExpr (AllGetters, loc),
					arguments, false, loc);

			if (get == null) {
				Invocation.Error_WrongNumArguments (loc, "this", arguments.Count);
				return null;
			}

			//
			// Only base will allow this invocation to happen.
			//
			if (get.IsAbstract && this is BaseIndexerAccess){
				Error_CannotCallAbstractBase (TypeManager.CSharpSignature (get));
				return null;
			}

			type = get.ReturnType;
			if (type.IsPointer && !ec.InUnsafe){
				UnsafeError (loc);
				return null;
			}

			instance_expr.CheckMarshalByRefAccess ();
			
			eclass = ExprClass.IndexerAccess;
			return this;
		}

		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) {
				Report.Error (1612, loc, "Cannot modify the return value of `{0}' because it is not a variable",
					      GetSignatureForError ());
				return null;
			}

			ArrayList AllSetters = new ArrayList();
			if (!CommonResolve (ec))
				return null;

			bool found_any = false, found_any_setters = false;

			Indexers ilist = Indexers.GetIndexersForType (current_type, indexer_type);
			if (ilist.Properties != null) {
				found_any = true;
				foreach (Indexers.Indexer ix in ilist.Properties) {
					if (ix.Setter != null)
						AllSetters.Add (ix.Setter);
				}
			}
			if (AllSetters.Count > 0) {
				found_any_setters = true;
				set_arguments = (ArrayList) arguments.Clone ();
				set_arguments.Add (new Argument (right_side, Argument.AType.Expression));
				set = (MethodInfo) Invocation.OverloadResolve (
					ec, new MethodGroupExpr (AllSetters, loc),
					set_arguments, false, loc);
			}

			if (!found_any) {
				Report.Error (21, loc, "Cannot apply indexing with [] to an expression of type `{0}'",
					      TypeManager.CSharpName (indexer_type));
				return null;
			}

			if (!found_any_setters) {
				Error (154, "indexer can not be used in this context, because " +
				       "it lacks a `set' accessor");
				return null;
			}

			if (set == null) {
				Invocation.Error_WrongNumArguments (loc, "this", arguments.Count);
				return null;
			}

			//
			// Only base will allow this invocation to happen.
			//
			if (set.IsAbstract && this is BaseIndexerAccess){
				Error_CannotCallAbstractBase (TypeManager.CSharpSignature (set));
				return null;
			}

			//
			// Now look for the actual match in the list of indexers to set our "return" type
			//
			type = TypeManager.void_type;	// default value
			foreach (Indexers.Indexer ix in ilist.Properties){
				if (ix.Setter == set){
					type = ix.PropertyInfo.PropertyType;
					break;
				}
			}

			instance_expr.CheckMarshalByRefAccess ();

			eclass = ExprClass.IndexerAccess;
			return this;
		}
		
		bool prepared = false;
		LocalTemporary temp;
		
		public void Emit (EmitContext ec, bool leave_copy)
		{
			Invocation.EmitCall (ec, is_base_indexer, false, instance_expr, get, arguments, loc, prepared, 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;
			Argument a = (Argument) set_arguments [set_arguments.Count - 1];
			
			if (prepared) {
				source.Emit (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);
				a.Expr = temp;
			}
			
			Invocation.EmitCall (ec, is_base_indexer, false, instance_expr, set, 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 ()
		{
			// FIXME: print the argument list of the indexer
			return instance_expr.GetSignatureForError () + ".this[...]";
		}
	}

	/// <summary>
	///   The base operator for method names
	/// </summary>
	public class BaseAccess : Expression {
		public readonly string Identifier;

		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;
		}

		TypeArguments args;

		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 (ec.IsStatic){
				Error (1511, "Keyword `base' is not available in a static method");
				return null;
			}

			if (ec.IsFieldInitializer){
				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) {
				MemberLookupFailed (ec.ContainerType, base_type, base_type, Identifier, null, true, loc);
				return null;
			}

			Expression left;
			
			if (ec.IsStatic)
				left = new TypeExpression (base_type, loc);
			else
				left = ec.GetThis (loc);

			MemberExpr me = (MemberExpr) member_lookup;
			
			Expression e = me.ResolveMemberAccess (ec, left, loc, null);

			if (e is PropertyExpr) {
				PropertyExpr pe = (PropertyExpr) e;

				pe.IsBase = true;
			}

			MethodGroupExpr mg = e as MethodGroupExpr;
			if (mg != null)
				mg.IsBase = true;

			if (args != null) {
				if (mg != null)
					return mg.ResolveGeneric (ec, args);

				Report.Error (307, loc, "`{0}' cannot be used with type arguments",
					      Identifier);
				return null;
			}

			return e;
		}

		public override void Emit (EmitContext ec)
		{
			throw new Exception ("Should never be called"); 
		}
	}

	/// <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;
		}
	}
	
	/// <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 EmptyExpression Null = new EmptyExpression ();

		public static readonly EmptyExpression OutAccess = new EmptyExpression ();
		public static readonly EmptyExpression LValueMemberAccess = new EmptyExpression ();
		public static readonly EmptyExpression LValueMemberOutAccess = 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;
		}

		// TODO: should be protected
		public EmptyExpression ()
		{
			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 DoResolve (EmitContext ec)
		{
			return this;
		}

		public override void Emit (EmitContext ec)
		{
			// nothing, as we only exist to not do anything.
		}

		//
		// 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;
		}
	}

	public class UserCast : Expression {
		MethodBase method;
		Expression source;
		
		public UserCast (MethodInfo method, Expression source, Location l)
		{
			this.method = method;
			this.source = source;
			type = method.ReturnType;
			eclass = ExprClass.Value;
			loc = l;
		}

		public Expression Source {
			get {
				return source;
			}
		}
			
		public override Expression DoResolve (EmitContext ec)
		{
			//
			// We are born fully resolved
			//
			return this;
		}

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

			source.Emit (ec);
			
			if (method is MethodInfo)
				ig.Emit (OpCodes.Call, (MethodInfo) method);
			else
				ig.Emit (OpCodes.Call, (ConstructorInfo) 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 {
		Expression left;
		string dim;
		
		public ComposedCast (Expression left, string dim)
			: this (left, dim, left.Location)
		{
		}

		public ComposedCast (Expression left, string dim, Location l)
		{
			this.left = left;
			this.dim = dim;
			loc = l;
		}

#if GMCS_SOURCE
		public Expression RemoveNullable ()
		{
			if (dim.EndsWith ("?")) {
				dim = dim.Substring (0, dim.Length - 1);
				if (dim == "")
					return left;
			}

			return this;
		}
#endif

		protected override TypeExpr DoResolveAsTypeStep (IResolveContext ec)
		{
			TypeExpr lexpr = left.ResolveAsTypeTerminal (ec, false);
			if (lexpr == null)
				return null;

			Type ltype = lexpr.Type;
			if ((ltype == TypeManager.void_type) && (dim != "*")) {
				Error_VoidInvalidInTheContext (loc);
				return null;
			}

#if GMCS_SOURCE
			if ((dim.Length > 0) && (dim [0] == '?')) {
				TypeExpr nullable = new NullableType (left, loc);
				if (dim.Length > 1)
					nullable = new ComposedCast (nullable, dim.Substring (1), loc);
				return nullable.ResolveAsTypeTerminal (ec, false);
			}
#endif

			if (dim == "*" && !TypeManager.VerifyUnManaged (ltype, loc))
				return null;

			if (dim != "" && dim [0] == '[' &&
			    (ltype == TypeManager.arg_iterator_type || ltype == TypeManager.typed_reference_type)) {
				Report.Error (611, loc, "Array elements cannot be of type `{0}'", TypeManager.CSharpName (ltype));
				return null;
			}

			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);
				return null;
			}

			eclass = ExprClass.Type;
			return this;
		}

		public override string Name {
			get { return left + dim; }
		}

		public override string FullName {
			get { return type.FullName; }
		}

		public override string GetSignatureForError ()
		{
			return left.GetSignatureForError () + dim;
		}
	}

	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 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);
		}
	}

	//
	// Used by the fixed statement
	//
	public class StringPtr : Expression {
		LocalBuilder b;
		
		public StringPtr (LocalBuilder b, Location l)
		{
			this.b = b;
			eclass = ExprClass.Value;
			type = TypeManager.char_ptr_type;
			loc = l;
		}

		public override Expression DoResolve (EmitContext ec)
		{
			// This should never be invoked, we are born in fully
			// initialized state.

			return this;
		}

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

			ig.Emit (OpCodes.Ldloc, b);
			ig.Emit (OpCodes.Conv_I);
			ig.Emit (OpCodes.Call, TypeManager.int_get_offset_to_string_data);
			ig.Emit (OpCodes.Add);
		}
	}
	
	//
	// 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 DoResolve (EmitContext ec)
		{
			count = count.Resolve (ec);
			if (count == null)
				return null;
			
			if (count.Type != TypeManager.int32_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;
				
			if (size == 0)
				ig.Emit (OpCodes.Sizeof, otype);
			else
				IntConstant.EmitInt (ig, size);
			count.Emit (ec);
			ig.Emit (OpCodes.Mul);
			ig.Emit (OpCodes.Localloc);
		}
	}
}