public Constant ImplicitConversionRequired (ResolveContext ec, TypeSpec type)
		{
			Constant c = ConvertImplicitly (type);
			if (c == null)
				Error_ValueCannotBeConverted (ec, type, false);

			return c;
		}

		protected override Expression DoResolve (ResolveContext ec)
		{
			var results = new List<string> ();

			ec.CurrentMemberDefinition.GetCompletionStartingWith (Prefix, results);

			throw new CompletionResult (Prefix, results.Distinct ().Select (l => l.Substring (Prefix.Length)).ToArray ());
		}

		public override void Error_ValueCannotBeConverted (ResolveContext ec, TypeSpec target, bool expl)
		{
			if (!expl && IsLiteral && type.BuiltinType != BuiltinTypeSpec.Type.Double &&
				BuiltinTypeSpec.IsPrimitiveTypeOrDecimal (target) &&
				BuiltinTypeSpec.IsPrimitiveTypeOrDecimal (type)) {
				ec.Report.Error (31, loc, "Constant value `{0}' cannot be converted to a `{1}'",
					GetValueAsLiteral (), target.GetSignatureForError ());
			} else {
				base.Error_ValueCannotBeConverted (ec, target, expl);
			}
		}

		static bool ConvertPromotion (ResolveContext rc, ref Constant prim, ref Constant second, TypeSpec type)
		{
			Constant c = prim.ConvertImplicitly (type);
			if (c != null) {
				prim = c;
				return true;
			}

			if (type.BuiltinType == BuiltinTypeSpec.Type.UInt) {
				type = rc.BuiltinTypes.Long;
				prim = prim.ConvertImplicitly (type);
				second = second.ConvertImplicitly (type);
				return prim != null && second != null;
			}

			return false;
		}

		//
		// Performs the numeric promotions on the left and right expresions
		// and deposits the results on `lc' and `rc'.
		//
		// On success, the types of `lc' and `rc' on output will always match,
		// and the pair will be one of:
		//
		// TODO: BinaryFold should be called as an optimization step only,
		// error checking here is weak
		//		
		static bool DoBinaryNumericPromotions (ResolveContext rc, ref Constant left, ref Constant right)
		{
			TypeSpec ltype = left.Type;
			TypeSpec rtype = right.Type;

			foreach (TypeSpec t in rc.BuiltinTypes.BinaryPromotionsTypes) {
				if (t == ltype)
					return t == rtype || ConvertPromotion (rc, ref right, ref left, t);

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

			left = left.ConvertImplicitly (rc.BuiltinTypes.Int);
			right = right.ConvertImplicitly (rc.BuiltinTypes.Int);
			return left != null && right != null;
		}

		public override void Error_ValueCannotBeConverted (ResolveContext ec, TypeSpec t, bool expl)
		{
			if (t.IsGenericParameter) {
				ec.Report.Error(403, loc,
					"Cannot convert null to the type parameter `{0}' because it could be a value " +
					"type. Consider using `default ({0})' instead", t.Name);
				return;
			}

			if (TypeSpec.IsValueType (t)) {
				ec.Report.Error(37, loc, "Cannot convert null to `{0}' because it is a value type",
					t.GetSignatureForError ());
				return;
			}

			base.Error_ValueCannotBeConverted (ec, t, expl);
		}

		protected override ParametersCompiled ResolveParameters (ResolveContext ec, TypeInferenceContext tic, TypeSpec delegateType)
		{
			if (!delegateType.IsDelegate)
				return null;

			AParametersCollection d_params = Delegate.GetParameters (delegateType);

			if (HasExplicitParameters) {
				if (!VerifyExplicitParameters (ec, tic, delegateType, d_params))
					return null;

				return Parameters;
			}

			//
			// If L has an implicitly typed parameter list we make implicit parameters explicit
			// Set each parameter of L is given the type of the corresponding parameter in D
			//
			if (!VerifyParameterCompatibility (ec, tic, delegateType, d_params, ec.IsInProbingMode))
				return null;

			TypeSpec [] ptypes = new TypeSpec [Parameters.Count];
			for (int i = 0; i < d_params.Count; i++) {
				// D has no ref or out parameters
				if ((d_params.FixedParameters[i].ModFlags & Parameter.Modifier.RefOutMask) != 0)
					return null;

				TypeSpec d_param = d_params.Types [i];

				//
				// When type inference context exists try to apply inferred type arguments
				//
				if (tic != null) {
					d_param = tic.InflateGenericArgument (ec, d_param);
				}

				ptypes [i] = d_param;
				ImplicitLambdaParameter ilp = (ImplicitLambdaParameter) Parameters.FixedParameters [i];
				ilp.SetParameterType (d_param);
				ilp.Resolve (null, i);
			}

			Parameters.Types = ptypes;
			return Parameters;
		}

		public override Constant ConvertInitializer (ResolveContext rc, Constant expr)
		{
			if (expr is EnumConstant)
				expr = ((EnumConstant) expr).Child;

			var en = (Enum)Parent;
			var underlying = en.UnderlyingType;
			if (expr != null) {
				expr = expr.ImplicitConversionRequired (rc, underlying);
				if (expr != null && !IsValidEnumType (expr.Type)) {
					en.Error_UnderlyingType (Location);
					expr = null;
				}
			}

			if (expr == null)
				expr = New.Constantify (underlying, Location);

			return new EnumConstant (expr, MemberType);
		}

		protected override Expression CreateExpressionTree (ResolveContext ec, TypeSpec delegate_type)
		{
			if (ec.IsInProbingMode)
				return this;

			BlockContext bc = new BlockContext (ec.MemberContext, ec.ConstructorBlock, ec.BuiltinTypes.Void) {
				CurrentAnonymousMethod = ec.CurrentAnonymousMethod
			};

			Expression args = Parameters.CreateExpressionTree (bc, loc);
			Expression expr = Block.CreateExpressionTree (ec);
			if (expr == null)
				return null;

			Arguments arguments = new Arguments (2);
			arguments.Add (new Argument (expr));
			arguments.Add (new Argument (args));
			return CreateExpressionFactoryCall (ec, "Lambda",
				new TypeArguments (new TypeExpression (delegate_type, loc)),
				arguments);
		}

		public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
		{
			if (right_side == EmptyExpression.OutAccess) {
				right_side.DoResolveLValue (rc, this);
				return null;
			}

			if (DoResolveCore (rc)) {
				setter_args = CreateSetterArguments (rc, right_side);
				setter = CreateCallSiteBinder (rc, setter_args, true);
			}

			eclass = ExprClass.Variable;
			return this;
		}

		public static DynamicUnaryConversion CreateIsFalse (ResolveContext rc, Arguments args, Location loc)
		{
			return new DynamicUnaryConversion ("IsFalse", args, loc) { type = rc.BuiltinTypes.Bool };
		}

		protected abstract Expression CreateCallSiteBinder (ResolveContext ec, Arguments args, bool isSet);

		protected virtual Arguments CreateSetterArguments (ResolveContext rc, Expression rhs)
		{
			var setter_args = new Arguments (Arguments.Count + 1);
			setter_args.AddRange (Arguments);
			setter_args.Add (new Argument (rhs));
			return setter_args;
		}

		protected override Expression DoResolve (ResolveContext rc)
		{
			if (DoResolveCore (rc))
				binder_expr = binder.CreateCallSiteBinder (rc, arguments);

			return this;
		}

		public override Expression CreateExpressionTree (ResolveContext ec)
		{
			return condition.CreateExpressionTree (ec);
		}

		internal static void Error_CompileTimeOverflow (ResolveContext rc, Location loc)
		{
			rc.Report.Error (220, loc, "The operation overflows at compile time in checked mode");
		}

		protected bool DoResolveCore (ResolveContext rc)
		{
			foreach (var arg in arguments) {
				if (arg.Type == InternalType.VarOutType) {
					// Should be special error message about dynamic dispatch
					rc.Report.Error (8047, arg.Expr.Location, "Declaration expression cannot be used in this context");
				}
			}

			if (rc.CurrentTypeParameters != null && rc.CurrentTypeParameters[0].IsMethodTypeParameter)
				context_mvars = rc.CurrentTypeParameters;

			int errors = rc.Report.Errors;
			var pt = rc.Module.PredefinedTypes;

			binder_type = pt.Binder.Resolve ();
			pt.CallSite.Resolve ();
			pt.CallSiteGeneric.Resolve ();

			eclass = ExprClass.Value;

			if (type == null)
				type = rc.BuiltinTypes.Dynamic;

			if (rc.Report.Errors == errors)
				return true;

			rc.Report.Error (1969, loc,
				"Dynamic operation cannot be compiled without `Microsoft.CSharp.dll' assembly reference");
			return false;
		}

		public override void Emit (EmitContext ec)
		{
			var rc = new ResolveContext (ec.MemberContext);
			var expr = new Conditional (new BooleanExpression (condition), invoke, assign, loc).Resolve (rc);
			expr.Emit (ec);
		}

		//
		// Creates a proxy base method call inside this container for hoisted base member calls
		//
		public MethodSpec CreateHoistedBaseCallProxy (ResolveContext rc, MethodSpec method)
		{
			Method proxy_method;

			//
			// One proxy per base method is enough
			//
			if (hoisted_base_call_proxies == null) {
				hoisted_base_call_proxies = new Dictionary<MethodSpec, Method> ();
				proxy_method = null;
			} else {
				hoisted_base_call_proxies.TryGetValue (method, out proxy_method);
			}

			if (proxy_method == null) {
				string name = CompilerGeneratedContainer.MakeName (method.Name, null, "BaseCallProxy", hoisted_base_call_proxies.Count);

				MemberName member_name;
				TypeArguments targs = null;
				TypeSpec return_type = method.ReturnType;
				var local_param_types = method.Parameters.Types;

				if (method.IsGeneric) {
					//
					// Copy all base generic method type parameters info
					//
					var hoisted_tparams = method.GenericDefinition.TypeParameters;
					var tparams = new TypeParameters ();

					targs = new TypeArguments ();
					targs.Arguments = new TypeSpec[hoisted_tparams.Length];
					for (int i = 0; i < hoisted_tparams.Length; ++i) {
						var tp = hoisted_tparams[i];
						var local_tp = new TypeParameter (tp, null, new MemberName (tp.Name, Location), null);
						tparams.Add (local_tp);

						targs.Add (new SimpleName (tp.Name, Location));
						targs.Arguments[i] = local_tp.Type;
					}

					member_name = new MemberName (name, tparams, Location);

					//
					// Mutate any method type parameters from original
					// to newly created hoisted version
					//
					var mutator = new TypeParameterMutator (hoisted_tparams, tparams);
					return_type = mutator.Mutate (return_type);
					local_param_types = mutator.Mutate (local_param_types);
				} else {
					member_name = new MemberName (name);
				}

				var base_parameters = new Parameter[method.Parameters.Count];
				for (int i = 0; i < base_parameters.Length; ++i) {
					var base_param = method.Parameters.FixedParameters[i];
					base_parameters[i] = new Parameter (new TypeExpression (local_param_types [i], Location),
						base_param.Name, base_param.ModFlags, null, Location);
					base_parameters[i].Resolve (this, i);
				}

				var cloned_params = ParametersCompiled.CreateFullyResolved (base_parameters, method.Parameters.Types);
				if (method.Parameters.HasArglist) {
					cloned_params.FixedParameters[0] = new Parameter (null, "__arglist", Parameter.Modifier.NONE, null, Location);
					cloned_params.Types[0] = Module.PredefinedTypes.RuntimeArgumentHandle.Resolve ();
				}

				// Compiler generated proxy
				proxy_method = new Method (this, new TypeExpression (return_type, Location),
					Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED | Modifiers.DEBUGGER_HIDDEN,
					member_name, cloned_params, null);

				var block = new ToplevelBlock (Compiler, proxy_method.ParameterInfo, Location) {
					IsCompilerGenerated = true
				};

				var mg = MethodGroupExpr.CreatePredefined (method, method.DeclaringType, Location);
				mg.InstanceExpression = new BaseThis (method.DeclaringType, Location);
				if (targs != null)
					mg.SetTypeArguments (rc, targs);

				// Get all the method parameters and pass them as arguments
				var real_base_call = new Invocation (mg, block.GetAllParametersArguments ());
				Statement statement;
				if (method.ReturnType.Kind == MemberKind.Void)
					statement = new StatementExpression (real_base_call);
				else
					statement = new Return (real_base_call, Location);

				block.AddStatement (statement);
				proxy_method.Block = block;

				members.Add (proxy_method);
				proxy_method.Define ();
				proxy_method.PrepareEmit ();

				hoisted_base_call_proxies.Add (method, proxy_method);
//.........这里部分代码省略.........

		/// <summary>
		///   Constant expression folder for binary operations.
		///
		///   Returns null if the expression can not be folded.
		/// </summary>
		static public Constant BinaryFold (ResolveContext ec, Binary.Operator oper,
						     Constant left, Constant right, Location loc)
		{
			Constant result = null;

			if (left is EmptyConstantCast)
				return BinaryFold (ec, oper, ((EmptyConstantCast)left).child, right, loc);

			if (left is SideEffectConstant) {
				result = BinaryFold (ec, oper, ((SideEffectConstant) left).value, right, loc);
				if (result == null)
					return null;
				return new SideEffectConstant (result, left, loc);
			}

			if (right is EmptyConstantCast)
				return BinaryFold (ec, oper, left, ((EmptyConstantCast)right).child, loc);

			if (right is SideEffectConstant) {
				result = BinaryFold (ec, oper, left, ((SideEffectConstant) right).value, loc);
				if (result == null)
					return null;
				return new SideEffectConstant (result, right, loc);
			}

			TypeSpec lt = left.Type;
			TypeSpec rt = right.Type;
			bool bool_res;

			if (lt.BuiltinType == BuiltinTypeSpec.Type.Bool && lt == rt) {
				bool lv = (bool) left.GetValue ();
				bool rv = (bool) right.GetValue ();			
				switch (oper) {
				case Binary.Operator.BitwiseAnd:
				case Binary.Operator.LogicalAnd:
					return new BoolConstant (ec.BuiltinTypes, lv && rv, left.Location);
				case Binary.Operator.BitwiseOr:
				case Binary.Operator.LogicalOr:
					return new BoolConstant (ec.BuiltinTypes, lv || rv, left.Location);
				case Binary.Operator.ExclusiveOr:
					return new BoolConstant (ec.BuiltinTypes, lv ^ rv, left.Location);
				case Binary.Operator.Equality:
					return new BoolConstant (ec.BuiltinTypes, lv == rv, left.Location);
				case Binary.Operator.Inequality:
					return new BoolConstant (ec.BuiltinTypes, lv != rv, left.Location);
				}
				return null;
			}

			//
			// During an enum evaluation, none of the rules are valid
			// Not sure whether it is bug in csc or in documentation
			//
			if (ec.HasSet (ResolveContext.Options.EnumScope)){
				if (left is EnumConstant)
					left = ((EnumConstant) left).Child;
				
				if (right is EnumConstant)
					right = ((EnumConstant) right).Child;
			} else if (left is EnumConstant && rt == lt) {
				switch (oper){
					///
					/// E operator |(E x, E y);
					/// E operator &(E x, E y);
					/// E operator ^(E x, E y);
					/// 
					case Binary.Operator.BitwiseOr:
					case Binary.Operator.BitwiseAnd:
					case Binary.Operator.ExclusiveOr:
						result = BinaryFold (ec, oper, ((EnumConstant)left).Child, ((EnumConstant)right).Child, loc);
						if (result != null)
							result = result.Reduce (ec, lt);
						return result;

					///
					/// U operator -(E x, E y);
					/// 
					case Binary.Operator.Subtraction:
						result = BinaryFold (ec, oper, ((EnumConstant)left).Child, ((EnumConstant)right).Child, loc);
						if (result != null)
							result = result.Reduce (ec, EnumSpec.GetUnderlyingType (lt));
						return result;

					///
					/// bool operator ==(E x, E y);
					/// bool operator !=(E x, E y);
					/// bool operator <(E x, E y);
					/// bool operator >(E x, E y);
					/// bool operator <=(E x, E y);
					/// bool operator >=(E x, E y);
					/// 
					case Binary.Operator.Equality:				
					case Binary.Operator.Inequality:
					case Binary.Operator.LessThan:				
					case Binary.Operator.GreaterThan:
//.........这里部分代码省略.........