Merged mcs.

ICSharpCode.NRefactory.CSharp/Parser/CSharpParser.cs

@@ -1431,12 +1431,12 @@ namespace ICSharpCode.NRefactory.CSharp
 					result.AddChild (new CSharpTokenNode (Convert (location [1]), 1), ForStatement.Roles.Semicolon);
 				if (forStatement.Test != null)
 					result.AddChild ((Expression)forStatement.Test.Accept (this), ForStatement.Roles.Condition);
-				if (location != null)
+				if (location != null && location.Count >= 3)
 					result.AddChild (new CSharpTokenNode (Convert (location [2]), 1), ForStatement.Roles.Semicolon);
 				
 				AddStatementOrList (result, forStatement.Increment, ForStatement.IteratorRole);
 				
-				if (location != null)
+				if (location != null && location.Count >= 4)
 					result.AddChild (new CSharpTokenNode (Convert (location [3]), 1), ForStatement.Roles.RPar);
 				
 				if (forStatement.Statement != null)

ICSharpCode.NRefactory.CSharp/Parser/mcs/anonymous.cs

@@ -1070,11 +1070,11 @@ namespace Mono.CSharp {
 			using (ec.Set (ResolveContext.Options.ProbingMode | ResolveContext.Options.InferReturnType)) {
 				var body = CompatibleMethodBody (ec, tic, InternalType.Arglist, delegate_type);
 				if (body != null) {
-					if (is_async) {
+					if (Block.IsAsync) {
 						AsyncInitializer.Create (ec, body.Block, body.Parameters, ec.CurrentMemberDefinition.Parent, null, loc);
 					}
 
-					am = body.Compatible (ec, body, is_async);
+					am = body.Compatible (ec, body);
 				} else {
 					am = null;
 				}
@@ -1135,7 +1135,7 @@ namespace Mono.CSharp {
 						// lambda, this also means no variable capturing between this
 						// and parent scope
 						//
-						am = body.Compatible (ec, ec.CurrentAnonymousMethod, is_async);
+						am = body.Compatible (ec, ec.CurrentAnonymousMethod);
 
 						//
 						// Quote nested expression tree
@@ -1156,7 +1156,7 @@ namespace Mono.CSharp {
 							am = CreateExpressionTree (ec, delegate_type);
 					}
 				} else {
-					if (is_async) {
+					if (Block.IsAsync) {
 						var rt = body.ReturnType;
 						if (rt.Kind != MemberKind.Void &&
 							rt != ec.Module.PredefinedTypes.Task.TypeSpec &&
@@ -1402,10 +1402,10 @@ namespace Mono.CSharp {
 
 		public AnonymousExpression Compatible (ResolveContext ec)
 		{
-			return Compatible (ec, this, false);
+			return Compatible (ec, this);
 		}
 
-		public AnonymousExpression Compatible (ResolveContext ec, AnonymousExpression ae, bool isAsync)
+		public AnonymousExpression Compatible (ResolveContext ec, AnonymousExpression ae)
 		{
 			if (block.Resolved)
 				return this;
@@ -1446,7 +1446,7 @@ namespace Mono.CSharp {
 				// If e is synchronous the inferred return type is T
 				// If e is asynchronous the inferred return type is Task<T>
 				//
-				if (isAsync && ReturnType != null) {
+				if (block.IsAsync && ReturnType != null) {
 					ReturnType = ec.Module.PredefinedTypes.TaskGeneric.TypeSpec.MakeGenericType (ec, new [] { ReturnType });
 				}
 			}

ICSharpCode.NRefactory.CSharp/Parser/mcs/async.cs

@@ -76,11 +76,6 @@ namespace Mono.CSharp
 
 			var bc = (BlockContext) rc;
 
-			if (!bc.CurrentBlock.ParametersBlock.IsAsync) {
-				// TODO: Should check for existence of await type but
-				// what to do with it
-			}
-
 			stmt = new AwaitStatement (expr, loc);
 			if (!stmt.Resolve (bc))
 				return null;
@@ -253,12 +248,11 @@ namespace Mono.CSharp
 			//
 			ec.AssertEmptyStack ();
 
-			var args = new Arguments (1);
 			var storey = (AsyncTaskStorey) machine_initializer.Storey;
-			var fe_cont = new FieldExpr (storey.Continuation, loc);
-			fe_cont.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
+			var cont_field = storey.EmitContinuationInitialization (ec);
 
-			args.Add (new Argument (fe_cont));
+			var args = new Arguments (1);
+			args.Add (new Argument (cont_field));
 
 			if (IsDynamic) {
 				var rc = new ResolveContext (ec.MemberContext);
@@ -456,7 +450,7 @@ namespace Mono.CSharp
 				}
 			}
 
-			if (!block.IsAsync) {
+			if (!block.HasAwait) {
 				host.Compiler.Report.Warning (1998, 1, loc,
 					"Async block lacks `await' operator and will run synchronously");
 			}
@@ -539,6 +533,8 @@ namespace Mono.CSharp
 		PropertySpec task;
 		LocalVariable hoisted_return;
 		int locals_captured;
+		Dictionary<TypeSpec, List<StackField>> stack_fields;
+		TypeSpec action;
 
 		public AsyncTaskStorey (IMemberContext context, AsyncInitializer initializer, TypeSpec type)
 			: base (initializer.OriginalBlock, initializer.Host,context.CurrentMemberDefinition as MemberBase, context.CurrentTypeParameters, "async")
@@ -554,12 +550,6 @@ namespace Mono.CSharp
 			}
 		}
 
-		public Field Continuation {
-			get {
-				return continuation;
-			}
-		}
-
 		public LocalVariable HoistedReturn {
 			get {
 				return hoisted_return;
@@ -585,24 +575,42 @@ namespace Mono.CSharp
 			return AddCapturedVariable ("$awaiter" + awaiters++.ToString ("X"), type);
 		}
 
-		public Field AddCapturedLocalVariable (TypeSpec type)
+		public StackField AddCapturedLocalVariable (TypeSpec type)
 		{
 			if (mutator != null)
 				type = mutator.Mutate (type);
 
-			var field = AddCompilerGeneratedField ("<s>$" + locals_captured++.ToString ("X"), new TypeExpression (type, Location), true);
+			List<StackField> existing_fields = null;
+			if (stack_fields == null) {
+				stack_fields = new Dictionary<TypeSpec, List<StackField>> ();
+			} else if (stack_fields.TryGetValue (type, out existing_fields)) {
+				foreach (var f in existing_fields) {
+					if (f.CanBeReused) {
+						f.CanBeReused = false;
+						return f;
+					}
+				}
+			}
+
+			const Modifiers mod = Modifiers.COMPILER_GENERATED | Modifiers.PRIVATE;
+			var field = new StackField (this, new TypeExpression (type, Location), mod, new MemberName ("<s>$" + locals_captured++.ToString ("X"), Location));
+			AddField (field);
+
 			field.Define ();
 
+			if (existing_fields == null) {
+				existing_fields = new List<StackField> ();
+				stack_fields.Add (type, existing_fields);
+			}
+
+			existing_fields.Add (field);
+
 			return field;
 		}
 
 		protected override bool DoDefineMembers ()
 		{
-			var action = Module.PredefinedTypes.Action.Resolve ();
-			if (action != null) {
-				continuation = AddCompilerGeneratedField ("$continuation", new TypeExpression (action, Location), true);
-				continuation.ModFlags |= Modifiers.READONLY;
-			}
+			action = Module.PredefinedTypes.Action.Resolve ();
 
 			PredefinedType builder_type;
 			PredefinedMember<MethodSpec> bf;
@@ -664,30 +672,13 @@ namespace Mono.CSharp
 			if (!base.DoDefineMembers ())
 				return false;
 
-			MethodGroupExpr mg;
 			var block = instance_constructors[0].Block;
 
-			//
-			// Initialize continuation with state machine method
-			//
-			if (continuation != null) {
-				var args = new Arguments (1);
-				mg = MethodGroupExpr.CreatePredefined (StateMachineMethod.Spec, spec, Location);
-				args.Add (new Argument (mg));
-
-				block.AddStatement (
-					new StatementExpression (new SimpleAssign (
-						new FieldExpr (continuation, Location),
-						new NewDelegate (action, args, Location),
-						Location
-				)));
-			}
-
-			mg = MethodGroupExpr.CreatePredefined (builder_factory, bt, Location);
+			var mg = MethodGroupExpr.CreatePredefined (builder_factory, bt, Location);
 			block.AddStatement (
 				new StatementExpression (new SimpleAssign (
-				new FieldExpr (builder, Location),
-				new Invocation (mg, new Arguments (0)),
+					new FieldExpr (builder, Location),
+					new Invocation (mg, new Arguments (0)),
 				Location)));
 
 			if (has_task_return_type) {
@@ -697,6 +688,54 @@ namespace Mono.CSharp
 			return true;
 		}
 
+		public Expression EmitContinuationInitialization (EmitContext ec)
+		{
+			//
+			// When more than 1 awaiter has been used in the block we
+			// introduce class scope field to cache continuation delegate
+			//
+			if (awaiters > 1) {
+				if (continuation == null) {
+					continuation = AddCompilerGeneratedField ("$continuation", new TypeExpression (action, Location), true);
+					continuation.Define ();
+				}
+
+				var fexpr = new FieldExpr (continuation, Location);
+				fexpr.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location);
+
+				//
+				// if ($continuation == null)
+				//    $continuation = new Action (MoveNext);
+				//
+				fexpr.Emit (ec);
+
+				var skip_cont_init = ec.DefineLabel ();
+				ec.Emit (OpCodes.Brtrue_S, skip_cont_init);
+
+				ec.EmitThis ();
+				EmitActionLoad (ec);
+				ec.Emit (OpCodes.Stfld, continuation.Spec);
+				ec.MarkLabel (skip_cont_init);
+
+				return fexpr;
+			}
+
+			//
+			// Otherwise simply use temporary local variable
+			//
+			var field = LocalVariable.CreateCompilerGenerated (action, OriginalSourceBlock, Location);
+			EmitActionLoad (ec);
+			field.EmitAssign (ec);
+			return new LocalVariableReference (field, Location);
+		}
+
+		void EmitActionLoad (EmitContext ec)
+		{
+			ec.EmitThis ();
+			ec.Emit (OpCodes.Ldftn, StateMachineMethod.Spec);
+			ec.Emit (OpCodes.Newobj, (MethodSpec) MemberCache.FindMember (action, MemberFilter.Constructor (null), BindingRestriction.DeclaredOnly));
+		}
+
 		public void EmitSetException (EmitContext ec, LocalVariableReference exceptionVariable)
 		{
 			//
@@ -735,4 +774,30 @@ namespace Mono.CSharp
 			mg.EmitCall (ec, args);
 		}
 	}
+
+	class StackField : Field
+	{
+		public StackField (DeclSpace parent, FullNamedExpression type, Modifiers mod, MemberName name)
+			: base (parent, type, mod, name, null)
+		{
+		}
+
+		public bool CanBeReused { get; set; }
+	}
+
+	class StackFieldExpr : FieldExpr
+	{
+		public StackFieldExpr (Field field)
+			: base (field, Location.Null)
+		{
+		}
+
+		public override void Emit (EmitContext ec)
+		{
+			base.Emit (ec);
+
+			var field = (StackField) spec.MemberDefinition;
+			field.CanBeReused = true;
+		}
+	}
 }

ICSharpCode.NRefactory.CSharp/Parser/mcs/codegen.cs

@@ -280,7 +280,7 @@ namespace Mono.CSharp
 		public FieldExpr GetTemporaryField (TypeSpec type)
 		{
 			var f = AsyncTaskStorey.AddCapturedLocalVariable (type);
-			var fexpr = new FieldExpr (f, Location.Null);
+			var fexpr = new StackFieldExpr (f);
 			fexpr.InstanceExpression = new CompilerGeneratedThis (CurrentType, Location.Null);
 			return fexpr;
 		}

ICSharpCode.NRefactory.CSharp/Parser/mcs/context.cs

@@ -469,10 +469,19 @@ namespace Mono.CSharp
 			if (CurrentAnonymousMethod == null)
 				return false;
 
-			// FIXME: IsIterator is too aggressive, we should capture only if child
-			// block contains yield
-			if (CurrentAnonymousMethod.IsIterator || CurrentAnonymousMethod is AsyncInitializer)
-				return true;
+			//
+			// Capture only if this or any of child blocks contain yield
+			// or it's a parameter
+			//
+			if (CurrentAnonymousMethod.IsIterator)
+				return local.IsParameter || CurrentBlock.Explicit.HasYield;
+
+			//
+			// Capture only if this or any of child blocks contain await
+			// or it's a parameter
+			//
+			if (CurrentAnonymousMethod is AsyncInitializer)
+				return CurrentBlock.Explicit.HasAwait;
 
 			return local.Block.ParametersBlock != CurrentBlock.ParametersBlock.Original;
 		}

ICSharpCode.NRefactory.CSharp/Parser/mcs/cs-parser.jay

@@ -3891,7 +3891,7 @@ unary_expression
 			report.Error (1992, GetLocation ($1),
 				"The `await' operator can only be used when its containing method or lambda expression is marked with the `async' modifier");
 		} else {
-			current_block.ParametersBlock.IsAsync = true;
+			current_block.Explicit.RegisterAsyncAwait ();
 		}
 		
 		$$ = new Await ((Expression) $2, GetLocation ($1));
@@ -4092,13 +4092,8 @@ conditional_expression
 	  }
 	;
 
-expression_recover
-	: expression
-	| error { $$ = new NullLiteral (GetLocation ($1)); }
-	;
-
 assignment_expression
-	: prefixed_unary_expression ASSIGN expression_recover
+	: prefixed_unary_expression ASSIGN expression
 	  {
 		$$ = new SimpleAssign ((Expression) $1, (Expression) $3, GetLocation ($2));
 	  }
@@ -5278,6 +5273,16 @@ for_statement_cont
 		
 		lbag.AddStatement (f, current_block.StartLocation, GetLocation ($2), GetLocation ($4), GetLocation ($6));
 
+		$$ = end_block (GetLocation ($2));
+	  }
+	| opt_for_initializer SEMICOLON error
+	  {
+		For f = new For ((Statement) $1, null, null, null, GetLocation ($-2));
+		current_block.AddStatement (f);
+		
+		lbag.AddStatement (f, current_block.StartLocation, GetLocation ($2));
+
+		Error_SyntaxError (yyToken);
 		$$ = end_block (GetLocation ($2));
 	  }
 	| error
@@ -5440,7 +5445,7 @@ yield_statement
 			FeatureIsNotAvailable (lt.Location, "iterators");
 		}
 		
-		current_block.ParametersBlock.TopBlock.IsIterator = true;
+		current_block.Explicit.RegisterIteratorYield ();
 		$$ = new Yield ((Expression) $3, lt.Location);
 		lbag.AddStatement ($$, GetLocation ($2), GetLocation ($4));
 	  }
@@ -5454,7 +5459,7 @@ yield_statement
 			FeatureIsNotAvailable (lt.Location, "iterators");
 		}
 		
-		current_block.ParametersBlock.TopBlock.IsIterator = true;
+		current_block.Explicit.RegisterIteratorYield ();
 		$$ = new YieldBreak (lt.Location);
 		lbag.AddStatement ($$, GetLocation ($2), GetLocation ($3));
 	  }
@@ -5629,20 +5634,20 @@ using_statement
 		current_block.AddLocalName (li);
 		current_variable = new Using.VariableDeclaration ((FullNamedExpression) $3, li);
 	  }
-	  using_or_fixed_variable_initializer opt_using_or_fixed_variable_declarators CLOSE_PARENS
+	  using_initialization CLOSE_PARENS
 	  {
 		$$ = current_variable;	  
 		current_variable = null;
 	  }
 	  embedded_statement
 	  {
-		if ($10 is EmptyStatement && lexer.peek_token () == Token.OPEN_BRACE)
-			Warning_EmptyStatement (GetLocation ($10));
+		if ($9 is EmptyStatement && lexer.peek_token () == Token.OPEN_BRACE)
+			Warning_EmptyStatement (GetLocation ($9));
 	  
-		Using u = new Using ((Using.VariableDeclaration) $9, (Statement) $10, GetLocation ($1));
-		lbag.AddStatement (u, GetLocation ($2), GetLocation ($8));
+		Using u = new Using ((Using.VariableDeclaration) $8, (Statement) $9, GetLocation ($1));
+		lbag.AddStatement (u, GetLocation ($2), GetLocation ($7));
 		current_block.AddStatement (u);
-		$$ = end_block (GetLocation ($8));
+		$$ = end_block (GetLocation ($7));
 	  }
 	| USING open_parens_any expression CLOSE_PARENS embedded_statement
 	  {
@@ -5655,6 +5660,15 @@ using_statement
 	  }
 	;
 	
+using_initialization
+	: using_or_fixed_variable_initializer opt_using_or_fixed_variable_declarators
+	| error
+	  {
+		// It has to be here for the parent to safely restore artificial block
+	  	Error_SyntaxError (yyToken);
+	  }
+	;
+	
 using_or_fixed_variable_initializer
 	: /* empty */
 	  {
@@ -6695,6 +6709,9 @@ AnonymousMethodExpression end_anonymous (ParametersBlock anon_block)
 {
 	AnonymousMethodExpression retval;
 
+	if (async_block)
+		anon_block.IsAsync = true;
+
 	current_anonymous_method.Block = anon_block;
 	retval = current_anonymous_method;
 

ICSharpCode.NRefactory.CSharp/Parser/mcs/decl.cs

@@ -27,6 +27,7 @@ using IKVM.Reflection.Emit;
 #else
 using System.Reflection;
 using System.Reflection.Emit;
+//using Mono.Collections.Generic;
 #endif
 
 namespace Mono.CSharp {

ICSharpCode.NRefactory.CSharp/Parser/mcs/ecore.cs

@@ -529,12 +529,12 @@ namespace Mono.CSharp {
 
 			//
 			// Store the result to temporary field when we
-			// cannot load this directly
+			// cannot load `this' directly
 			//
 			var field = ec.GetTemporaryField (type);
 			if (needs_temporary) {
 				//
-				// Create temporary local (we cannot load this before Emit)
+				// Create temporary local (we cannot load `this' before Emit)
 				//
 				var temp = ec.GetTemporaryLocal (type);
 				ec.Emit (OpCodes.Stloc, temp);
@@ -841,7 +841,7 @@ namespace Mono.CSharp {
 			      name, was, expected);
 		}
 
-		public void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
+		public virtual void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
 		{
 			string [] valid = new string [4];
 			int count = 0;
@@ -3692,7 +3692,7 @@ namespace Mono.CSharp {
 				//
 				if (p.IsGenericTask || q.IsGenericTask) {
 					var async_am = a.Expr as AnonymousMethodExpression;
-					if (async_am != null && async_am.IsAsync) {
+					if (async_am != null && async_am.Block.IsAsync) {
 
 						if (p.IsGenericTask != q.IsGenericTask) {
 							return 0;
@@ -5358,10 +5358,7 @@ namespace Mono.CSharp {
 		
 		public void Emit (EmitContext ec, bool leave_copy)
 		{
-			bool is_volatile = false;
-
-			if ((spec.Modifiers & Modifiers.VOLATILE) != 0)
-				is_volatile = true;
+			bool is_volatile = (spec.Modifiers & Modifiers.VOLATILE) != 0;
 
 			spec.MemberDefinition.SetIsUsed ();
 			

ICSharpCode.NRefactory.CSharp/Parser/mcs/expression.cs

@@ -9176,6 +9176,10 @@ namespace Mono.CSharp
 			return this;
 		}
 
+		public override void Error_UnexpectedKind (ResolveContext ec, ResolveFlags flags, Location loc)
+		{
+		}
+
 		public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
 		{
 		}

ICSharpCode.NRefactory.CSharp/Parser/mcs/iterators.cs

@@ -158,7 +158,6 @@ namespace Mono.CSharp
 		}
 
 		Field pc_field;
-		int local_name_idx;
 		StateMachineMethod method;
 
 		protected StateMachine (Block block, TypeContainer parent, MemberBase host, TypeParameter[] tparams, string name)
@@ -197,11 +196,6 @@ namespace Mono.CSharp
 
 			return base.DoDefineMembers ();
 		}
-
-		protected override string GetVariableMangledName (LocalVariable local_info)
-		{
-			return "<" + local_info.Name + ">__" + local_name_idx++.ToString ("X");
-		}
 	}
 
 	class IteratorStorey : StateMachine
@@ -390,6 +384,7 @@ namespace Mono.CSharp
 		TypeExpr iterator_type_expr;
 		Field current_field;
 		Field disposing_field;
+		int local_name_idx;
 
 		TypeExpr enumerator_type;
 		TypeExpr enumerable_type;
@@ -563,6 +558,11 @@ namespace Mono.CSharp
 			base.EmitHoistedParameters (ec, hoisted);
 			base.EmitHoistedParameters (ec, hoisted_params_copy);
 		}
+
+		protected override string GetVariableMangledName (LocalVariable local_info)
+		{
+			return "<" + local_info.Name + ">__" + local_name_idx++.ToString ("X");
+		}
 	}
 
 	public class StateMachineMethod : Method

ICSharpCode.NRefactory.CSharp/Parser/mcs/linq.cs

@@ -352,6 +352,12 @@ namespace Mono.CSharp.Linq
 			}
 		}
 
+		public bool IsParameter {
+			get {
+				return false;
+			}
+		}
+
 		public Location Location { get; private set; }
 
 		public string Name { get; private set; }

ICSharpCode.NRefactory.CSharp/Parser/mcs/statement.cs

@@ -1299,6 +1299,7 @@ namespace Mono.CSharp {
 		Block Block { get; }
 		Expression CreateReferenceExpression (ResolveContext rc, Location loc);
 		bool IsDeclared { get; }
+		bool IsParameter { get; }
 		Location Location { get; }
 	}
 
@@ -1457,6 +1458,13 @@ namespace Mono.CSharp {
 					if (Initializer != null) {
 						((VarExpr) type_expr).InferType (bc, Initializer);
 						type = type_expr.Type;
+					} else {
+						// Set error type to indicate the var was placed correctly but could
+						// not be infered
+						//
+						// var a = missing ();
+						//
+						type = InternalType.ErrorType;
 					}
 				}
 
@@ -1717,6 +1725,12 @@ namespace Mono.CSharp {
 			}
 		}
 
+		bool INamedBlockVariable.IsParameter {
+			get {
+				return false;
+			}
+		}
+
 		public bool IsReadonly {
 			get {
 				return (flags & Flags.ReadonlyMask) != 0;
@@ -1907,13 +1921,14 @@ namespace Mono.CSharp {
 			Unchecked = 1,
 			HasRet = 8,
 			Unsafe = 16,
-			IsIterator = 32,
 			HasCapturedVariable = 64,
 			HasCapturedThis = 1 << 7,
 			IsExpressionTree = 1 << 8,
 			CompilerGenerated = 1 << 9,
-			IsAsync = 1 << 10,
-			Resolved = 1 << 11
+			HasAsyncModifier = 1 << 10,
+			Resolved = 1 << 11,
+			YieldBlock = 1 << 12,
+			AwaitBlock = 1 << 13
 		}
 
 		public Block Parent;
@@ -2303,6 +2318,12 @@ namespace Mono.CSharp {
 			}
 		}
 
+		public bool HasAwait {
+			get {
+				return (flags & Flags.AwaitBlock) != 0;
+			}
+		}
+
 		public bool HasCapturedThis {
 			set { flags = value ? flags | Flags.HasCapturedThis : flags & ~Flags.HasCapturedThis; }
 			get {
@@ -2317,6 +2338,12 @@ namespace Mono.CSharp {
 			}
 		}
 
+		public bool HasYield {
+			get {
+				return (flags & Flags.YieldBlock) != 0;
+			}
+		}
+
 		#endregion
 
 		//
@@ -2325,15 +2352,17 @@ namespace Mono.CSharp {
 		public AnonymousMethodStorey CreateAnonymousMethodStorey (ResolveContext ec)
 		{
 			//
-			// An iterator has only 1 storey block
+			// Return same story for iterator and async blocks unless we are
+			// in nested anonymous method
 			//
-			if (ec.CurrentAnonymousMethod.IsIterator)
-			    return ec.CurrentAnonymousMethod.Storey;
+			if (ec.CurrentAnonymousMethod is StateMachineInitializer && ParametersBlock.Original == ec.CurrentAnonymousMethod.Block.Original)
+				return ec.CurrentAnonymousMethod.Storey;
 
 			//
-			// When referencing a variable in iterator storey from children anonymous method
+			// When referencing a variable in parent iterator/async storey
+			// from nested anonymous method
 			//
-			if (ParametersBlock.am_storey is IteratorStorey) {
+			if (ParametersBlock.am_storey is StateMachine) {
 				return ParametersBlock.am_storey;
 			}
 
@@ -2420,6 +2449,32 @@ namespace Mono.CSharp {
 			am_storey.Parent.PartialContainer.AddCompilerGeneratedClass (am_storey);
 		}
 
+		public void RegisterAsyncAwait ()
+		{
+			var block = this;
+			while ((block.flags & Flags.AwaitBlock) == 0) {
+				block.flags |= Flags.AwaitBlock;
+
+				if (block.Parent == null)
+					return;
+
+				block = block.Parent.Explicit;
+			}
+		}
+
+		public void RegisterIteratorYield ()
+		{
+			var block = this;
+			while ((block.flags & Flags.YieldBlock) == 0) {
+				block.flags |= Flags.YieldBlock;
+
+				if (block.Parent == null)
+					return;
+
+				block = block.Parent.Explicit;
+			}
+		}
+
 		public void WrapIntoDestructor (TryFinally tf, ExplicitBlock tryBlock)
 		{
 			tryBlock.statements = statements;
@@ -2461,6 +2516,12 @@ namespace Mono.CSharp {
 				}
 			}
 
+			public bool IsParameter {
+				get {
+					return true;
+				}
+			}
+
 			public bool IsLocked {
 				get {
 					return is_locked;
@@ -2556,6 +2617,8 @@ namespace Mono.CSharp {
 			this.parameters = parameters;
 			ParametersBlock = this;
 
+			flags |= (parent.ParametersBlock.flags & (Flags.YieldBlock | Flags.AwaitBlock));
+
 			this.top_block = parent.ParametersBlock.top_block;
 			ProcessParameters ();
 		}
@@ -2595,13 +2658,12 @@ namespace Mono.CSharp {
 
 		#region Properties
 
-		public bool IsAsync
-		{
+		public bool IsAsync {
 			get {
-				return (flags & Flags.IsAsync) != 0;
+				return (flags & Flags.HasAsyncModifier) != 0;
 			}
 			set {
-				flags = value ? flags | Flags.IsAsync : flags & ~Flags.IsAsync;
+				flags = value ? flags | Flags.HasAsyncModifier : flags & ~Flags.HasAsyncModifier;
 			}
 		}
 
@@ -2631,7 +2693,7 @@ namespace Mono.CSharp {
 
 		public bool Resolved {
 			get {
-				return resolved;
+				return (flags & Flags.Resolved) != 0;
 			}
 		}
 
@@ -2805,12 +2867,14 @@ namespace Mono.CSharp {
 			ParametersBlock pb = new ParametersBlock (this, ParametersCompiled.EmptyReadOnlyParameters, StartLocation);
 			pb.EndLocation = EndLocation;
 			pb.statements = statements;
+			pb.original = this;
 
 			var iterator = new Iterator (pb, method, host, iterator_type, is_enumerable);
 			am_storey = new IteratorStorey (iterator);
 
 			statements = new List<Statement> (1);
 			AddStatement (new Return (iterator, iterator.Location));
+			flags &= ~Flags.YieldBlock;
 		}
 
 		public void WrapIntoAsyncTask (IMemberContext context, TypeContainer host, TypeSpec returnType)
@@ -2818,6 +2882,7 @@ namespace Mono.CSharp {
 			ParametersBlock pb = new ParametersBlock (this, ParametersCompiled.EmptyReadOnlyParameters, StartLocation);
 			pb.EndLocation = EndLocation;
 			pb.statements = statements;
+			pb.original = this;
 
 			var block_type = host.Module.Compiler.BuiltinTypes.Void;
 			var initializer = new AsyncInitializer (pb, host, block_type);
@@ -2827,6 +2892,7 @@ namespace Mono.CSharp {
 
 			statements = new List<Statement> (1);
 			AddStatement (new StatementExpression (initializer));
+			flags &= ~Flags.AwaitBlock;
 		}
 	}
 
@@ -2873,13 +2939,9 @@ namespace Mono.CSharp {
 			top_block = this;
 		}
 
-		public bool IsIterator
-		{
+		public bool IsIterator {
 			get {
-				return (flags & Flags.IsIterator) != 0;
-			}
-			set {
-				flags = value ? flags | Flags.IsIterator : flags & ~Flags.IsIterator;
+				return HasYield;
 			}
 		}