Updated mcs.

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

@@ -130,24 +130,24 @@ namespace Mono.CompilerServices.SymbolWriter
 
 		public int NumLineNumbers;
 
-		internal MonoSymbolFile ()
+		public MonoSymbolFile ()
 		{
 			ot = new OffsetTable ();
 		}
 
-		internal int AddSource (SourceFileEntry source)
+		public int AddSource (SourceFileEntry source)
 		{
 			sources.Add (source);
 			return sources.Count;
 		}
 
-		internal int AddCompileUnit (CompileUnitEntry entry)
+		public int AddCompileUnit (CompileUnitEntry entry)
 		{
 			comp_units.Add (entry);
 			return comp_units.Count;
 		}
 
-		internal void AddMethod (MethodEntry entry)
+		public void AddMethod (MethodEntry entry)
 		{
 			methods.Add (entry);
 		}

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

@@ -601,6 +601,11 @@ namespace Mono.CompilerServices.SymbolWriter
 			DataOffset = reader.ReadInt32 ();
 		}
 
+		public void ReadAll ()
+		{
+			ReadData ();
+		}
+
 		void ReadData ()
 		{
 			if (creating)
@@ -746,6 +751,7 @@ namespace Mono.CompilerServices.SymbolWriter
 
 		public string FileName {
 			get { return file_name; }
+			set { file_name = value; }
 		}
 
 		public bool AutoGenerated {
@@ -1208,6 +1214,15 @@ namespace Mono.CompilerServices.SymbolWriter
 			bw.WriteLeb128 ((int) flags);
 		}
 
+		public void ReadAll ()
+		{
+			GetLineNumberTable ();
+			GetLocals ();
+			GetCodeBlocks ();
+			GetScopeVariables ();
+			GetRealName ();
+		}
+
 		public LineNumberTable GetLineNumberTable ()
 		{
 			lock (SymbolFile) {

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

@@ -47,11 +47,7 @@ namespace Mono.CompilerServices.SymbolWriter
 		string filename;
 		
 		private SourceMethodBuilder current_method;
-#if NET_2_1
-		System.Collections.Stack current_method_stack = new System.Collections.Stack ();
-#else
 		Stack<SourceMethodBuilder> current_method_stack = new Stack<SourceMethodBuilder> ();
-#endif
 
 		public MonoSymbolWriter (string filename)
 		{

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

@@ -37,11 +37,7 @@ namespace Mono.CompilerServices.SymbolWriter
 		List<LocalVariableEntry> _locals;
 		List<CodeBlockEntry> _blocks;
 		List<ScopeVariable> _scope_vars;
-#if NET_2_1
-		System.Collections.Stack _block_stack;
-#else		
 		Stack<CodeBlockEntry> _block_stack;
-#endif
 		readonly List<LineNumberEntry> method_lines;
 
 		readonly ICompileUnit _comp_unit;
@@ -90,11 +86,7 @@ namespace Mono.CompilerServices.SymbolWriter
 		public void StartBlock (CodeBlockEntry.Type type, int start_offset)
 		{
 			if (_block_stack == null) {
-#if NET_2_1
-				_block_stack = new System.Collections.Stack ();
-#else				
 				_block_stack = new Stack<CodeBlockEntry> ();
-#endif
 			}
 			
 			if (_blocks == null)

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

@@ -1368,7 +1368,7 @@ namespace Mono.CSharp {
 				b = b.ConvertToAsyncTask (ec, ec.CurrentMemberDefinition.Parent.PartialContainer, p, return_type, loc);
 			}
 
-			return CompatibleMethodFactory (return_type ?? InternalType.Arglist, delegate_type, p, b);
+			return CompatibleMethodFactory (return_type ?? InternalType.ErrorType, delegate_type, p, b);
 		}
 
 		protected virtual AnonymousMethodBody CompatibleMethodFactory (TypeSpec return_type, TypeSpec delegate_type, ParametersCompiled p, ParametersBlock b)
@@ -1635,21 +1635,25 @@ namespace Mono.CSharp {
 				parent = storey = FindBestMethodStorey ();
 
 				if (storey == null) {
-					var sm = src_block.ParametersBlock.TopBlock.StateMachine;
+					var top_block = src_block.ParametersBlock.TopBlock;
+					var sm = top_block.StateMachine;
 
-					//
-					// Remove hoisted this demand when simple instance method is enough (no hoisted variables only this)
-					//
-					if (src_block.HasCapturedThis && src_block.ParametersBlock.StateMachine == null) {
-						src_block.ParametersBlock.TopBlock.RemoveThisReferenceFromChildrenBlock (src_block);
+					if (src_block.HasCapturedThis) {
+						//
+						// Remove hoisted 'this' request when simple instance method is
+						// enough (no hoisted variables only 'this')
+						//
+						if (src_block.ParametersBlock.StateMachine == null)
+							top_block.RemoveThisReferenceFromChildrenBlock (src_block);
 
 						//
 						// Special case where parent class is used to emit instance method
-						// because currect storey is of value type (async host) and we don't
-						// want to create another childer storey to host this reference only
+						// because currect storey is of value type (async host). We cannot
+						// use ldftn on non-boxed instances either to share mutated state
 						//
-						if (sm != null && sm.Kind == MemberKind.Struct)
+						if (sm != null && sm.Kind == MemberKind.Struct) {
 							parent = sm.Parent.PartialContainer;
+						}
 					}
 
 					//

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

@@ -154,6 +154,8 @@ namespace Mono.CSharp
 			}
 		}
 
+		public bool IsSatelliteAssembly { get; private set; }
+
 		public string Name {
 			get {
 				return name;
@@ -214,6 +216,7 @@ namespace Mono.CSharp
 					builder_extra.SetCulture (value, a.Location);
 				}
 
+				IsSatelliteAssembly = true;
 				return;
 			}
 
@@ -457,26 +460,28 @@ namespace Mono.CSharp
 				}
 			}
 
-			if (!wrap_non_exception_throws_custom) {
-				PredefinedAttribute pa = module.PredefinedAttributes.RuntimeCompatibility;
-				if (pa.IsDefined && pa.ResolveBuilder ()) {
-					var prop = module.PredefinedMembers.RuntimeCompatibilityWrapNonExceptionThrows.Get ();
-					if (prop != null) {
-						AttributeEncoder encoder = new AttributeEncoder ();
-						encoder.EncodeNamedPropertyArgument (prop, new BoolLiteral (Compiler.BuiltinTypes, true, Location.Null));
-						SetCustomAttribute (pa.Constructor, encoder.ToArray ());
+			if (!IsSatelliteAssembly) {
+				if (!wrap_non_exception_throws_custom) {
+					PredefinedAttribute pa = module.PredefinedAttributes.RuntimeCompatibility;
+					if (pa.IsDefined && pa.ResolveBuilder ()) {
+						var prop = module.PredefinedMembers.RuntimeCompatibilityWrapNonExceptionThrows.Get ();
+						if (prop != null) {
+							AttributeEncoder encoder = new AttributeEncoder ();
+							encoder.EncodeNamedPropertyArgument (prop, new BoolLiteral (Compiler.BuiltinTypes, true, Location.Null));
+							SetCustomAttribute (pa.Constructor, encoder.ToArray ());
+						}
 					}
 				}
-			}
 
-			if (declarative_security != null) {
+				if (declarative_security != null) {
 #if STATIC
-				foreach (var entry in declarative_security) {
-					Builder.__AddDeclarativeSecurity (entry);
-				}
+					foreach (var entry in declarative_security) {
+						Builder.__AddDeclarativeSecurity (entry);
+					}
 #else
-				throw new NotSupportedException ("Assembly-level security");
+					throw new NotSupportedException ("Assembly-level security");
 #endif
+				}
 			}
 
 			CheckReferencesPublicToken ();
@@ -1104,8 +1109,8 @@ namespace Mono.CSharp
 			this.compiler = compiler;
 
 			paths = new List<string> ();
-			paths.AddRange (compiler.Settings.ReferencesLookupPaths);
 			paths.Add (Directory.GetCurrentDirectory ());
+			paths.AddRange (compiler.Settings.ReferencesLookupPaths);
 		}
 
 		public abstract bool HasObjectType (T assembly);

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

@@ -129,13 +129,15 @@ namespace Mono.CSharp
 
 	public class AwaitStatement : YieldStatement<AsyncInitializer>
 	{
-		sealed class AwaitableMemberAccess : MemberAccess
+		public sealed class AwaitableMemberAccess : MemberAccess
 		{
 			public AwaitableMemberAccess (Expression expr)
 				: base (expr, "GetAwaiter")
 			{
 			}
 
+			public bool ProbingMode { get; set; }
+
 			protected override void Error_TypeDoesNotContainDefinition (ResolveContext rc, TypeSpec type, string name)
 			{
 				Error_OperatorCannotBeApplied (rc, type);
@@ -143,6 +145,9 @@ namespace Mono.CSharp
 
 			protected override void Error_OperatorCannotBeApplied (ResolveContext rc, TypeSpec type)
 			{
+				if (ProbingMode)
+					return;
+
 				var invocation = LeftExpression as Invocation;
 				if (invocation != null && invocation.MethodGroup != null && (invocation.MethodGroup.BestCandidate.Modifiers & Modifiers.ASYNC) != 0) {
 					rc.Report.Error (4008, loc, "Cannot await void method `{0}'. Consider changing method return type to `Task'",
@@ -169,8 +174,7 @@ namespace Mono.CSharp
 		}
 
 		Field awaiter;
-		PropertySpec is_completed;
-		MethodSpec get_result;
+		AwaiterDefinition awaiter_definition;
 		TypeSpec type;
 		TypeSpec result_type;
 
@@ -183,7 +187,7 @@ namespace Mono.CSharp
 
 		bool IsDynamic {
 			get {
-				return is_completed == null;
+				return awaiter_definition == null;
 			}
 		}
 
@@ -211,12 +215,12 @@ namespace Mono.CSharp
 			if (IsDynamic) {
 				var rc = new ResolveContext (ec.MemberContext);
 				return new Invocation (new MemberAccess (fe_awaiter, "GetResult"), new Arguments (0)).Resolve (rc);
-			} else {
-				var mg_result = MethodGroupExpr.CreatePredefined (get_result, fe_awaiter.Type, loc);
-				mg_result.InstanceExpression = fe_awaiter;
-
-				return new GetResultInvocation (mg_result, new Arguments (0));
 			}
+			
+			var mg_result = MethodGroupExpr.CreatePredefined (awaiter_definition.GetResult, fe_awaiter.Type, loc);
+			mg_result.InstanceExpression = fe_awaiter;
+
+			return new GetResultInvocation (mg_result, new Arguments (0));
 		}
 
 		public void EmitPrologue (EmitContext ec)
@@ -247,7 +251,7 @@ namespace Mono.CSharp
 				dargs.Add (new Argument (completed_expr));
 				completed_expr = new DynamicConversion (ec.Module.Compiler.BuiltinTypes.Bool, 0, dargs, loc).Resolve (rc);
 			} else {
-				var pe = PropertyExpr.CreatePredefined (is_completed, loc);
+				var pe = PropertyExpr.CreatePredefined (awaiter_definition.IsCompleted, loc);
 				pe.InstanceExpression = fe_awaiter;
 				completed_expr = pe;
 			}
@@ -309,9 +313,8 @@ namespace Mono.CSharp
 			if (!base.Resolve (bc))
 				return false;
 
-			Arguments args = new Arguments (0);
-
 			type = expr.Type;
+			Arguments args = new Arguments (0);
 
 			//
 			// The await expression is of dynamic type
@@ -343,44 +346,22 @@ namespace Mono.CSharp
 			}
 
 			var awaiter_type = ama.Type;
-			expr = ama;
-
-			//
-			// Predefined: bool IsCompleted { get; } 
-			//
-			is_completed = MemberCache.FindMember (awaiter_type, MemberFilter.Property ("IsCompleted", bc.Module.Compiler.BuiltinTypes.Bool),
-				BindingRestriction.InstanceOnly) as PropertySpec;
 
-			if (is_completed == null || !is_completed.HasGet) {
-				Error_WrongAwaiterPattern (bc, awaiter_type);
-				return false;
-			}
+			awaiter_definition = bc.Module.GetAwaiter (awaiter_type);
 
-			//
-			// Predefined: GetResult ()
-			//
-			// The method return type is also result type of await expression
-			//
-			get_result = MemberCache.FindMember (awaiter_type, MemberFilter.Method ("GetResult", 0,
-				ParametersCompiled.EmptyReadOnlyParameters, null),
-				BindingRestriction.InstanceOnly) as MethodSpec;
-
-			if (get_result == null) {
+			if (!awaiter_definition.IsValidPattern) {
 				Error_WrongAwaiterPattern (bc, awaiter_type);
 				return false;
 			}
 
-			//
-			// Predefined: INotifyCompletion.OnCompleted (System.Action)
-			//
-			var nc = bc.Module.PredefinedTypes.INotifyCompletion;
-			if (nc.Define () && !awaiter_type.ImplementsInterface (nc.TypeSpec, false)) {
+			if (!awaiter_definition.INotifyCompletion) {
 				bc.Report.Error (4027, loc, "The awaiter type `{0}' must implement interface `{1}'",
-					awaiter_type.GetSignatureForError (), nc.GetSignatureForError ());
+					awaiter_type.GetSignatureForError (), bc.Module.PredefinedTypes.INotifyCompletion.GetSignatureForError ());
 				return false;
 			}
 
-			result_type = get_result.ReturnType;
+			expr = ama;
+			result_type = awaiter_definition.GetResult.ReturnType;
 
 			return true;
 		}

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

@@ -1366,22 +1366,12 @@ namespace Mono.CSharp
 
 			if (proxy_method == null) {
 				string name = CompilerGeneratedContainer.MakeName (method.Name, null, "BaseCallProxy", hoisted_base_call_proxies.Count);
-				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 (method.Parameters.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 ();
-				}
 
 				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
@@ -1393,19 +1383,42 @@ namespace Mono.CSharp
 					targs.Arguments = new TypeSpec[hoisted_tparams.Length];
 					for (int i = 0; i < hoisted_tparams.Length; ++i) {
 						var tp = hoisted_tparams[i];
-						tparams.Add (new TypeParameter (tp, null, new MemberName (tp.Name, Location), null));
+						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] = tp;
+						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 (method.ReturnType, Location),
+				proxy_method = new Method (this, new TypeExpression (return_type, Location),
 					Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED | Modifiers.DEBUGGER_HIDDEN,
 					member_name, cloned_params, null);
 

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

@@ -704,7 +704,7 @@ namespace Mono.CSharp {
 			if (expr.Type == InternalType.Arglist)
 				return target_type == ec.Module.PredefinedTypes.ArgIterator.TypeSpec;
 
-			return ImplicitUserConversion (ec, expr, target_type, Location.Null) != null;
+			return UserDefinedConversion (ec, expr, target_type, true, true, Location.Null) != null;
 		}
 
 		//
@@ -917,17 +917,20 @@ namespace Mono.CSharp {
 		//
 		static TypeSpec FindMostSpecificSource (List<MethodSpec> list, TypeSpec sourceType, Expression source, bool apply_explicit_conv_rules)
 		{
-			var src_types_set = new TypeSpec [list.Count];
+			TypeSpec[] src_types_set = null;
 
 			//
 			// Try exact match first, if any operator converts from S then Sx = S
 			//
-			for (int i = 0; i < src_types_set.Length; ++i) {
+			for (int i = 0; i < list.Count; ++i) {
 				TypeSpec param_type = list [i].Parameters.Types [0];
 
 				if (param_type == sourceType)
 					return param_type;
 
+				if (src_types_set == null)
+					src_types_set = new TypeSpec [list.Count];
+
 				src_types_set [i] = param_type;
 			}
 
@@ -961,7 +964,7 @@ namespace Mono.CSharp {
 		static public TypeSpec FindMostSpecificTarget (IList<MethodSpec> list,
 							   TypeSpec target, bool apply_explicit_conv_rules)
 		{
-			var tgt_types_set = new List<TypeSpec> ();
+			List<TypeSpec> tgt_types_set = null;
 
 			//
 			// If any operator converts to T then Tx = T
@@ -971,6 +974,12 @@ namespace Mono.CSharp {
 				if (ret_type == target)
 					return ret_type;
 
+				if (tgt_types_set == null) {
+					tgt_types_set = new List<TypeSpec> (list.Count);
+				} else if (tgt_types_set.Contains (ret_type)) {
+					continue;
+				}
+
 				tgt_types_set.Add (ret_type);
 			}
 
@@ -1005,7 +1014,7 @@ namespace Mono.CSharp {
 		/// </summary>
 		static public Expression ImplicitUserConversion (ResolveContext ec, Expression source, TypeSpec target, Location loc)
 		{
-			return UserDefinedConversion (ec, source, target, true, loc);
+			return UserDefinedConversion (ec, source, target, true, false, loc);
 		}
 
 		/// <summary>
@@ -1013,7 +1022,7 @@ namespace Mono.CSharp {
 		/// </summary>
 		static Expression ExplicitUserConversion (ResolveContext ec, Expression source, TypeSpec target, Location loc)
 		{
-			return UserDefinedConversion (ec, source, target, false, loc);
+			return UserDefinedConversion (ec, source, target, false, false, loc);
 		}
 
 		static void FindApplicableUserDefinedConversionOperators (IList<MemberSpec> operators, Expression source, TypeSpec target, bool implicitOnly, ref List<MethodSpec> candidates)
@@ -1077,7 +1086,7 @@ namespace Mono.CSharp {
 		//
 		// User-defined conversions
 		//
-		static Expression UserDefinedConversion (ResolveContext ec, Expression source, TypeSpec target, bool implicitOnly, Location loc)
+		static Expression UserDefinedConversion (ResolveContext ec, Expression source, TypeSpec target, bool implicitOnly, bool probingOnly, Location loc)
 		{
 			List<MethodSpec> candidates = null;
 
@@ -1173,19 +1182,24 @@ namespace Mono.CSharp {
 				}
 
 				if (most_specific_operator == null) {
-					MethodSpec ambig_arg = null;
-					foreach (var candidate in candidates) {
-						if (candidate.ReturnType == t_x)
-							most_specific_operator = candidate;
-						else if (candidate.Parameters.Types[0] == s_x)
-							ambig_arg = candidate;
+					//
+					// Unless running in probing more
+					//
+					if (!probingOnly) {
+						MethodSpec ambig_arg = null;
+						foreach (var candidate in candidates) {
+							if (candidate.ReturnType == t_x)
+								most_specific_operator = candidate;
+							else if (candidate.Parameters.Types[0] == s_x)
+								ambig_arg = candidate;
+						}
+
+						ec.Report.Error (457, loc,
+							"Ambiguous user defined operators `{0}' and `{1}' when converting from `{2}' to `{3}'",
+							ambig_arg.GetSignatureForError (), most_specific_operator.GetSignatureForError (),
+							source.Type.GetSignatureForError (), target.GetSignatureForError ());
 					}
 
-					ec.Report.Error (457, loc,
-						"Ambiguous user defined operators `{0}' and `{1}' when converting from `{2}' to `{3}'",
-						ambig_arg.GetSignatureForError (), most_specific_operator.GetSignatureForError (),
-						source.Type.GetSignatureForError (), target.GetSignatureForError ());
-
 					return ErrorExpression.Instance;
 				}
 			}

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

@@ -951,10 +951,10 @@ struct_declaration
 	  opt_partial
 	  STRUCT
 	  {
-		lexer.ConstraintsParsing = true;
 	  }
 	  type_declaration_name
 	  { 
+		lexer.ConstraintsParsing = true;
 		push_current_container (new Struct (current_container, (MemberName) $6, (Modifiers) $2, (Attributes) $1), $3);
 		lbag.AddMember (current_container, GetModifierLocations (), GetLocation ($4));
 	  }
@@ -1539,7 +1539,7 @@ fixed_parameter
 	: opt_attributes
 	  opt_parameter_modifier
 	  parameter_type
-	  IDENTIFIER
+	  identifier_inside_body
 	  {
 		var lt = (Tokenizer.LocatedToken) $4;
 		$$ = new Parameter ((FullNamedExpression) $3, lt.Value, (Parameter.Modifier) $2, (Attributes) $1, lt.Location);
@@ -1548,7 +1548,7 @@ fixed_parameter
 	| opt_attributes
 	  opt_parameter_modifier
 	  parameter_type
-	  IDENTIFIER OPEN_BRACKET CLOSE_BRACKET
+	  identifier_inside_body OPEN_BRACKET CLOSE_BRACKET
 	  {
 		var lt = (Tokenizer.LocatedToken) $4;
 		report.Error (1552, lt.Location, "Array type specifier, [], must appear before parameter name");
@@ -1574,7 +1574,7 @@ fixed_parameter
 	| opt_attributes
 	  opt_parameter_modifier
 	  parameter_type
-	  IDENTIFIER
+	  identifier_inside_body
 	  ASSIGN
 	  {
 	  	++lexer.parsing_block;
@@ -1952,10 +1952,10 @@ interface_declaration
 	  opt_partial
 	  INTERFACE
 	  {
-		lexer.ConstraintsParsing = true;
 	  }
 	  type_declaration_name
 	  {
+		lexer.ConstraintsParsing = true;
 		push_current_container (new Interface (current_container, (MemberName) $6, (Modifiers) $2, (Attributes) $1), $3);
 		lbag.AddMember (current_container, GetModifierLocations (), GetLocation ($4));		
 	  }
@@ -3219,28 +3219,28 @@ parenthesized_expression
 	;
 	
 member_access
-	: primary_expression DOT IDENTIFIER opt_type_argument_list
+	: primary_expression DOT identifier_inside_body opt_type_argument_list
 	  {
 		var lt = (Tokenizer.LocatedToken) $3;
 		$$ = new MemberAccess ((Expression) $1, lt.Value, (TypeArguments) $4, lt.Location) {
 			DotLocation = GetLocation ($2)
 		};
 	  }
-	| builtin_types DOT IDENTIFIER opt_type_argument_list
+	| builtin_types DOT identifier_inside_body opt_type_argument_list
 	  {
 		var lt = (Tokenizer.LocatedToken) $3;
 		$$ = new MemberAccess ((Expression) $1, lt.Value, (TypeArguments) $4, lt.Location) {
 			DotLocation = GetLocation ($2)
 		};
 	  }
-	| BASE DOT IDENTIFIER opt_type_argument_list
+	| BASE DOT identifier_inside_body opt_type_argument_list
 	  {
 		var lt = (Tokenizer.LocatedToken) $3;
 		$$ = new MemberAccess (new BaseThis (GetLocation ($1)), lt.Value, (TypeArguments) $4, lt.Location) {
 			DotLocation = GetLocation ($2)
 		};
 	  }
-	| qualified_alias_member IDENTIFIER opt_type_argument_list
+	| qualified_alias_member identifier_inside_body opt_type_argument_list
 	  {
 		var lt1 = (Tokenizer.LocatedToken) $1;
 		var lt2 = (Tokenizer.LocatedToken) $2;
@@ -3284,7 +3284,7 @@ invocation_expression
 
 		$$ = new Invocation ((Expression) $1, null);
 		lbag.AddLocation ($$, GetLocation ($2));
-	  }	
+	  }
 	;
 
 opt_object_or_collection_initializer
@@ -3344,6 +3344,12 @@ member_initializer
 	  	$$ = new ElementInitializer (lt.Value, (Expression)$3, lt.Location);
 	  	lbag.AddLocation ($$, GetLocation ($2));
 	  }
+	| AWAIT ASSIGN initializer_value
+	  {
+	  	var lt = (Tokenizer.LocatedToken) Error_AwaitAsIdentifier ($1);
+	  	$$ = new ElementInitializer (lt.Value, (Expression)$3, lt.Location);
+	  	lbag.AddLocation ($$, GetLocation ($2));
+	  }
 	| GENERATE_COMPLETION 
 	  {
 		$$ = new CompletionElementInitializer (null, GetLocation ($1));
@@ -3680,13 +3686,13 @@ anonymous_type_parameters
 	;
 
 anonymous_type_parameter
-	: IDENTIFIER ASSIGN variable_initializer
+	: identifier_inside_body ASSIGN variable_initializer
 	  {
 		var lt = (Tokenizer.LocatedToken)$1;
 	  	$$ = new AnonymousTypeParameter ((Expression)$3, lt.Value, lt.Location);
 	  	lbag.AddLocation ($$, GetLocation ($2));
 	  }
-	| IDENTIFIER
+	| identifier_inside_body
 	  {
 		var lt = (Tokenizer.LocatedToken)$1;
 	  	$$ = new AnonymousTypeParameter (new SimpleName (lt.Value, lt.Location),
@@ -4537,6 +4543,11 @@ lambda_parameter
 	  	var lt = (Tokenizer.LocatedToken) $1;
 		$$ = new ImplicitLambdaParameter (lt.Value, lt.Location);
 	  }
+	| AWAIT
+	  {
+	  	var lt = (Tokenizer.LocatedToken) Error_AwaitAsIdentifier ($1);
+		$$ = new ImplicitLambdaParameter (lt.Value, lt.Location);
+	  }
 	;
 
 opt_lambda_parameter_list
@@ -4593,6 +4604,17 @@ lambda_expression
 		$$ = end_anonymous ((ParametersBlock) $4);
 		lbag.AddLocation ($$, GetLocation ($2));
 	  }
+	| AWAIT ARROW
+	  {
+		var lt = (Tokenizer.LocatedToken) Error_AwaitAsIdentifier ($1);
+		Parameter p = new ImplicitLambdaParameter (lt.Value, lt.Location);
+		start_anonymous (true, new ParametersCompiled (p), false, lt.Location);
+	  }
+	  lambda_expression_body
+	  {
+		$$ = end_anonymous ((ParametersBlock) $4);
+		lbag.AddLocation ($$, GetLocation ($2));
+	  }
 	| ASYNC identifier_inside_body ARROW
 	  {
 		var lt = (Tokenizer.LocatedToken) $2;
@@ -4687,10 +4709,11 @@ class_declaration
 	  opt_partial
 	  CLASS
 	  {
-		lexer.ConstraintsParsing = true;
 	  }
 	  type_declaration_name
 	  {
+		lexer.ConstraintsParsing = true;
+
 		Class c = new Class (current_container, (MemberName) $6, (Modifiers) $2, (Attributes) $1);
 		if (((c.ModFlags & Modifiers.STATIC) != 0) && lang_version == LanguageVersion.ISO_1) {
 			FeatureIsNotAvailable (c.Location, "static classes");
@@ -5303,10 +5326,7 @@ identifier_inside_body
 	: IDENTIFIER
 	| AWAIT
 	  {
-		if (async_block) {
-			report.Error (4003, GetLocation ($1), "`await' cannot be used as an identifier within an async method or lambda expression");
-			$$ = new Tokenizer.LocatedToken ("await", GetLocation ($1));
-		}
+	  	$$ = Error_AwaitAsIdentifier ($1);
 	  }
 	;
 
@@ -7059,6 +7079,16 @@ void Error_MissingInitializer (Location loc)
 	report.Error (210, loc, "You must provide an initializer in a fixed or using statement declaration");
 }
 
+object Error_AwaitAsIdentifier (object token)
+{
+	if (async_block) {
+		report.Error (4003, GetLocation (token), "`await' cannot be used as an identifier within an async method or lambda expression");
+		return new Tokenizer.LocatedToken ("await", GetLocation (token));
+	}
+
+	return token;
+}
+
 void push_current_container (TypeDefinition tc, object partial_token)
 {
 	if (module.Evaluator != null){

ICSharpCode.NRefactory.CSharp/Parser/mcs/cs-tokenizer.cs

@@ -197,7 +197,7 @@ namespace Mono.CSharp
 		readonly int tab_size;
 		bool handle_get_set = false;
 		bool handle_remove_add = false;
-		bool handle_where = false;
+		bool handle_where;
 		bool handle_typeof = false;
 		bool lambda_arguments_parsing;
 		List<Location> escaped_identifiers;
@@ -710,7 +710,7 @@ namespace Mono.CSharp
 				}
 				break;
 			case Token.WHERE:
-				if (!handle_where && !query_parsing)
+				if (!(handle_where && current_token != Token.COLON) && !query_parsing)
 					res = -1;
 				break;
 			case Token.FROM:
@@ -719,7 +719,7 @@ namespace Mono.CSharp
 				// followed by any token except ; , =
 				// 
 				if (!query_parsing) {
-					if (lambda_arguments_parsing) {
+					if (lambda_arguments_parsing || parsing_block == 0) {
 						res = -1;
 						break;
 					}
@@ -742,7 +742,7 @@ namespace Mono.CSharp
 					case Token.UINT:
 					case Token.ULONG:
 						next_token = xtoken ();
-						if (next_token == Token.SEMICOLON || next_token == Token.COMMA || next_token == Token.EQUALS)
+						if (next_token == Token.SEMICOLON || next_token == Token.COMMA || next_token == Token.EQUALS || next_token == Token.ASSIGN)
 							goto default;
 						
 						res = Token.FROM_FIRST;
@@ -782,6 +782,7 @@ namespace Mono.CSharp
 			case Token.NAMESPACE:
 				// TODO: some explanation needed
 				check_incorrect_doc_comment ();
+				parsing_modifiers = false;
 				break;
 				
 			case Token.PARTIAL:
@@ -815,8 +816,17 @@ namespace Mono.CSharp
 					Report.Error (267, Location,
 						"The `partial' modifier can be used only immediately before `class', `struct', `interface', or `void' keyword");
 					return token ();
-				}					
+				}
 
+				// HACK: A token is not a keyword so we need to restore identifiers buffer
+				// which has been overwritten before we grabbed the identifier
+				id_builder[0] = 'p';
+				id_builder[1] = 'a';
+				id_builder[2] = 'r';
+				id_builder[3] = 't';
+				id_builder[4] = 'i';
+				id_builder[5] = 'a';
+				id_builder[6] = 'l';
 				res = -1;
 				break;
 
@@ -839,8 +849,10 @@ namespace Mono.CSharp
 					case Token.IDENTIFIER:
 						PushPosition ();
 						xtoken ();
-						if (xtoken () != Token.ARROW)
+						if (xtoken () != Token.ARROW) {
+							PopPosition ();
 							goto default;
+						}
 
 						PopPosition ();
 						break;
@@ -964,8 +976,12 @@ namespace Mono.CSharp
 					//
 					// Expression inside parens is single type, (int[])
 					//
-					if (is_type)
+					if (is_type) {
+						if (current_token == Token.SEMICOLON)
+							return Token.OPEN_PARENS;
+
 						return Token.OPEN_PARENS_CAST;
+					}
 
 					//
 					// Expression is possible cast, look at next token, (T)null
@@ -1022,6 +1038,7 @@ namespace Mono.CSharp
 					continue;
 
 				case Token.IDENTIFIER:
+				case Token.AWAIT:
 					switch (ptoken) {
 					case Token.DOT:
 						if (bracket_level == 0) {
@@ -1274,6 +1291,7 @@ namespace Mono.CSharp
 			case Token.OP_GENERICS_GT:
 			case Token.INTERR:
 			case Token.OP_COALESCING:
+			case Token.COLON:
 				next_token = Token.INTERR_NULLABLE;
 				break;
 				
@@ -1412,7 +1430,7 @@ namespace Mono.CSharp
 							// if we have not seen anything in between
 							// report this error
 							//
-							Report.Warning (78, 4, Location, "The 'l' suffix is easily confused with the digit '1' (use 'L' for clarity)");
+							Report.Warning (78, 4, Location, "The `l' suffix is easily confused with the digit `1' (use `L' for clarity)");
 						}
 
 						goto case 'L';

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

@@ -175,28 +175,31 @@ namespace Mono.CSharp
 			bool keep_include_node = false;
 			string file = el.GetAttribute ("file");
 			string path = el.GetAttribute ("path");
+
 			if (file == "") {
 				Report.Warning (1590, 1, mc.Location, "Invalid XML `include' element. Missing `file' attribute");
 				el.ParentNode.InsertBefore (el.OwnerDocument.CreateComment (" Include tag is invalid "), el);
 				keep_include_node = true;
-			}
-			else if (path.Length == 0) {
+			} else if (path.Length == 0) {
 				Report.Warning (1590, 1, mc.Location, "Invalid XML `include' element. Missing `path' attribute");
 				el.ParentNode.InsertBefore (el.OwnerDocument.CreateComment (" Include tag is invalid "), el);
 				keep_include_node = true;
-			}
-			else {
+			} else {
 				XmlDocument doc;
-				if (!StoredDocuments.TryGetValue (file, out doc)) {
+				Exception exception = null;
+				var full_path = Path.Combine (Path.GetDirectoryName (mc.Location.NameFullPath), file);
+
+				if (!StoredDocuments.TryGetValue (full_path, out doc)) {
 					try {
 						doc = new XmlDocument ();
-						doc.Load (file);
-						StoredDocuments.Add (file, doc);
-					} catch (Exception) {
+						doc.Load (full_path);
+						StoredDocuments.Add (full_path, doc);
+					} catch (Exception e) {
+						exception = e;
 						el.ParentNode.InsertBefore (el.OwnerDocument.CreateComment (String.Format (" Badly formed XML in at comment file `{0}': cannot be included ", file)), el);
-						Report.Warning (1592, 1, mc.Location, "Badly formed XML in included comments file -- `{0}'", file);
 					}
 				}
+
 				if (doc != null) {
 					try {
 						XmlNodeList nl = doc.SelectNodes (path);
@@ -208,11 +211,17 @@ namespace Mono.CSharp
 						foreach (XmlNode n in nl)
 							el.ParentNode.InsertBefore (el.OwnerDocument.ImportNode (n, true), el);
 					} catch (Exception ex) {
+						exception = ex;
 						el.ParentNode.InsertBefore (el.OwnerDocument.CreateComment (" Failed to insert some or all of included XML "), el);
-						Report.Warning (1589, 1, mc.Location, "Unable to include XML fragment `{0}' of file `{1}' ({2})", path, file, ex.Message);
 					}
 				}
+
+				if (exception != null) {
+					Report.Warning (1589, 1, mc.Location, "Unable to include XML fragment `{0}' of file `{1}'. {2}",
+						path, file, exception.Message);
+				}
 			}
+
 			return keep_include_node;
 		}
 

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

@@ -1067,7 +1067,10 @@ namespace Mono.CSharp {
 			if (es == null)
 				Error_InvalidExpressionStatement (ec);
 
-			if (!(e is Assign) && (e.Type.IsGenericTask || e.Type == ec.Module.PredefinedTypes.Task.TypeSpec)) {
+			//
+			// This is quite expensive warning, try to limit the damage
+			//
+			if (MemberAccess.IsValidDotExpression (e.Type) && !(e is Assign || e is Await)) {
 				WarningAsyncWithoutWait (ec, e);
 			}
 
@@ -1077,6 +1080,30 @@ namespace Mono.CSharp {
 		static void WarningAsyncWithoutWait (BlockContext bc, Expression e)
 		{
 			if (bc.CurrentAnonymousMethod is AsyncInitializer) {
+				var awaiter = new AwaitStatement.AwaitableMemberAccess (e) {
+					ProbingMode = true
+				};
+
+				//
+				// Need to do full resolve because GetAwaiter can be extension method
+				// available only in this context
+				//
+				var mg = awaiter.Resolve (bc) as MethodGroupExpr;
+				if (mg == null)
+					return;
+
+				var arguments = new Arguments (0);
+				mg = mg.OverloadResolve (bc, ref arguments, null, OverloadResolver.Restrictions.ProbingOnly);
+				if (mg == null)
+					return;
+
+				//
+				// Use same check rules as for real await
+				//
+				var awaiter_definition = bc.Module.GetAwaiter (mg.BestCandidateReturnType);
+				if (!awaiter_definition.IsValidPattern || !awaiter_definition.INotifyCompletion)
+					return;
+
 				bc.Report.Warning (4014, 1, e.Location,
 					"The statement is not awaited and execution of current method continues before the call is completed. Consider using `await' operator");
 				return;
@@ -3523,7 +3550,7 @@ namespace Mono.CSharp {
 				best_candidate_return = best_candidate.ReturnType;
 			}
 
-			if (best_candidate.IsGeneric && TypeParameterSpec.HasAnyTypeParameterConstrained (best_candidate.GenericDefinition)) {
+			if (best_candidate.IsGeneric && (restr & OverloadResolver.Restrictions.ProbingOnly) == 0 && TypeParameterSpec.HasAnyTypeParameterConstrained (best_candidate.GenericDefinition)) {
 				ConstraintChecker cc = new ConstraintChecker (ec);
 				cc.CheckAll (best_candidate.GetGenericMethodDefinition (), best_candidate.TypeArguments, best_candidate.Constraints, loc);
 			}
@@ -4915,7 +4942,7 @@ namespace Mono.CSharp {
 				}
 			}
 
-			if (invocable_member != null) {
+			if (invocable_member != null && !IsProbingOnly) {
 				rc.Report.SymbolRelatedToPreviousError (best_candidate);
 				rc.Report.SymbolRelatedToPreviousError (invocable_member);
 				rc.Report.Warning (467, 2, loc, "Ambiguity between method `{0}' and invocable non-method `{1}'. Using method group",
@@ -4937,7 +4964,7 @@ namespace Mono.CSharp {
 			//
 			// Don't run possibly expensive checks in probing mode
 			//
-			if (!rc.IsInProbingMode) {
+			if (!IsProbingOnly && !rc.IsInProbingMode) {
 				//
 				// Check ObsoleteAttribute on the best method
 				//
@@ -6528,8 +6555,9 @@ namespace Mono.CSharp {
 			// Don't capture temporary variables except when using
 			// state machine redirection and block yields
 			//
-			if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator &&
-				ec.CurrentBlock.Explicit.HasYield && ec.IsVariableCapturingRequired) {
+			if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod is StateMachineInitializer &&
+				(ec.CurrentBlock.Explicit.HasYield || ec.CurrentBlock.Explicit.HasAwait) &&
+				ec.IsVariableCapturingRequired) {
 				AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
 				storey.CaptureLocalVariable (ec, li);
 			}

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

@@ -223,9 +223,16 @@ namespace Mono.CSharp
 
 				bool partial_input;
 				CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
+
+				// Terse mode, try to provide the trailing semicolon automatically.
 				if (parser == null && Terse && partial_input){
 					bool ignore;
-					parser = ParseString (ParseMode.Silent, input + ";", out ignore);
+
+					// check if the source would compile with a block, if so, we should not
+					// add the semicolon.
+					var needs_block = ParseString (ParseMode.Silent, input + "{}", out ignore) != null;
+					if (!needs_block)
+						parser = ParseString (ParseMode.Silent, input + ";", out ignore);
 				}
 				if (parser == null){
 					compiled = null;

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

@@ -4659,6 +4659,8 @@ namespace Mono.CSharp
 					}
 
 					true_expr = conv;
+					if (true_expr.Type != type)
+						true_expr = EmptyCast.Create (true_expr, type);
 				} else if ((conv = Convert.ImplicitConversion (ec, false_expr, true_type, loc)) != null) {
 					false_expr = conv;
 				} else {
@@ -4696,6 +4698,18 @@ namespace Mono.CSharp
 			expr.EmitBranchable (ec, false_target, false);
 			true_expr.Emit (ec);
 
+			//
+			// Verifier doesn't support interface merging. When there are two types on
+			// the stack without common type hint and the common type is an interface.
+			// Use temporary local to give verifier hint on what type to unify the stack
+			//
+			if (type.IsInterface && true_expr is EmptyCast && false_expr is EmptyCast) {
+				var temp = ec.GetTemporaryLocal (type);
+				ec.Emit (OpCodes.Stloc, temp);
+				ec.Emit (OpCodes.Ldloc, temp);
+				ec.FreeTemporaryLocal (temp, type);
+			}
+
 			ec.Emit (OpCodes.Br, end_target);
 			ec.MarkLabel (false_target);
 			false_expr.Emit (ec);
@@ -7258,7 +7272,7 @@ namespace Mono.CSharp
 		}
 	}
 
-	public class RefValueExpr : ShimExpression
+	public class RefValueExpr : ShimExpression, IAssignMethod
 	{
 		FullNamedExpression texpr;
 		
@@ -7296,13 +7310,44 @@ namespace Mono.CSharp
 			return this;
 		}
 
+		public override Expression DoResolveLValue (ResolveContext rc, Expression right_side)
+		{
+			return DoResolve (rc);
+		}
+
 		public override void Emit (EmitContext ec)
 		{
 			expr.Emit (ec);
 			ec.Emit (OpCodes.Refanyval, type);
 			ec.EmitLoadFromPtr (type);
 		}
-		
+
+		public void Emit (EmitContext ec, bool leave_copy)
+		{
+			throw new NotImplementedException ();
+		}
+
+		public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
+		{
+			expr.Emit (ec);
+			ec.Emit (OpCodes.Refanyval, type);
+			source.Emit (ec);
+
+			LocalTemporary temporary = null;
+			if (leave_copy) {
+				ec.Emit (OpCodes.Dup);
+				temporary = new LocalTemporary (source.Type);
+				temporary.Store (ec);
+			}
+
+			ec.EmitStoreFromPtr (type);
+
+			if (temporary != null) {
+				temporary.Emit (ec);
+				temporary.Release (ec);
+			}
+		}
+
 		public override object Accept (StructuralVisitor visitor)
 		{
 			return visitor.Visit (this);

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

@@ -364,7 +364,7 @@ namespace Mono.CSharp {
 		
 		Constraints constraints;
 		GenericTypeParameterBuilder builder;
-		TypeParameterSpec spec;
+		readonly TypeParameterSpec spec;
 
 		public TypeParameter (int index, MemberName name, Constraints constraints, Attributes attrs, Variance variance)
 			: base (null, name, attrs)
@@ -381,7 +381,7 @@ namespace Mono.CSharp {
 		{
 			this.spec = new TypeParameterSpec (null, -1, this, SpecialConstraint.None, variance, null);
 		}
-
+		
 		public TypeParameter (TypeParameterSpec spec, TypeSpec parentSpec, MemberName name, Attributes attrs)
 			: base (null, name, attrs)
 		{
@@ -391,7 +391,7 @@ namespace Mono.CSharp {
 				TypeArguments = spec.TypeArguments
 			};
 		}
-
+		
 		#region Properties
 
 		public override AttributeTargets AttributeTargets {
@@ -1480,6 +1480,7 @@ namespace Mono.CSharp {
 	{
 		readonly TypeParameters mvar;
 		readonly TypeParameters var;
+		readonly TypeParameterSpec[] src;
 		Dictionary<TypeSpec, TypeSpec> mutated_typespec;
 
 		public TypeParameterMutator (TypeParameters mvar, TypeParameters var)
@@ -1491,6 +1492,15 @@ namespace Mono.CSharp {
 			this.var = var;
 		}
 
+		public TypeParameterMutator (TypeParameterSpec[] srcVar, TypeParameters destVar)
+		{
+			if (srcVar.Length != destVar.Count)
+				throw new ArgumentException ();
+
+			this.src = srcVar;
+			this.var = destVar;
+		}
+
 		#region Properties
 
 		public TypeParameters MethodTypeParameters {
@@ -1530,9 +1540,16 @@ namespace Mono.CSharp {
 
 		public TypeParameterSpec Mutate (TypeParameterSpec tp)
 		{
-			for (int i = 0; i < mvar.Count; ++i) {
-				if (mvar[i].Type == tp)
-					return var[i].Type;
+			if (mvar != null) {
+				for (int i = 0; i < mvar.Count; ++i) {
+					if (mvar[i].Type == tp)
+						return var[i].Type;
+				}
+			} else {
+				for (int i = 0; i < src.Length; ++i) {
+					if (src[i] == tp)
+						return var[i].Type;
+				}
 			}
 
 			return tp;
@@ -3233,7 +3250,7 @@ namespace Mono.CSharp {
 			AParametersCollection d_parameters = invoke.Parameters;
 			return AllTypesAreFixed (d_parameters.Types);
 		}
-		
+
 		bool IsFixed (TypeSpec type)
 		{
 			return IsUnfixed (type) == -1;
@@ -3440,7 +3457,7 @@ namespace Mono.CSharp {
 				var invoke = Delegate.GetInvokeMethod (t);
 				TypeSpec rtype = invoke.ReturnType;
 
-				if (!rtype.IsGenericParameter && !TypeManager.IsGenericType (rtype))
+				if (!IsReturnTypeNonDependent (ec, invoke, rtype))
 					return 0;
 
 				// LAMESPEC: Standard does not specify that all methodgroup arguments
@@ -3453,9 +3470,6 @@ namespace Mono.CSharp {
 					if (inflated == null)
 						return 0;
 
-					if (IsUnfixed (inflated) >= 0)
-						return 0;
-
 					param_types[i] = inflated;
 				}
 

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

@@ -113,6 +113,7 @@ namespace Mono.CSharp
 		readonly Dictionary<TypeSpec, PointerContainer> pointer_types;
 		readonly Dictionary<TypeSpec, ReferenceContainer> reference_types;
 		readonly Dictionary<TypeSpec, MethodSpec> attrs_cache;
+		readonly Dictionary<TypeSpec, AwaiterDefinition> awaiters;
 
 		AssemblyDefinition assembly;
 		readonly CompilerContext context;
@@ -144,6 +145,7 @@ namespace Mono.CSharp
 			pointer_types = new Dictionary<TypeSpec, PointerContainer> ();
 			reference_types = new Dictionary<TypeSpec, ReferenceContainer> ();
 			attrs_cache = new Dictionary<TypeSpec, MethodSpec> ();
+			awaiters = new Dictionary<TypeSpec, AwaiterDefinition> ();
 		}
 
 		#region Properties
@@ -424,7 +426,7 @@ namespace Mono.CSharp
 			if (OptAttributes != null)
 				OptAttributes.Emit ();
 
-			if (Compiler.Settings.Unsafe) {
+			if (Compiler.Settings.Unsafe && !assembly.IsSatelliteAssembly) {
 				var pa = PredefinedAttributes.UnverifiableCode;
 				if (pa.IsDefined)
 					pa.EmitAttribute (builder);
@@ -472,6 +474,43 @@ namespace Mono.CSharp
 			return null;
 		}
 
+		//
+		// Return container with awaiter definition. It never returns null
+		// but all container member can be null for easier error reporting
+		//
+		public AwaiterDefinition GetAwaiter (TypeSpec type)
+		{
+			AwaiterDefinition awaiter;
+			if (awaiters.TryGetValue (type, out awaiter))
+				return awaiter;
+
+			awaiter = new AwaiterDefinition ();
+
+			//
+			// Predefined: bool IsCompleted { get; } 
+			//
+			awaiter.IsCompleted = MemberCache.FindMember (type, MemberFilter.Property ("IsCompleted", Compiler.BuiltinTypes.Bool),
+				BindingRestriction.InstanceOnly) as PropertySpec;
+
+			//
+			// Predefined: GetResult ()
+			//
+			// The method return type is also result type of await expression
+			//
+			awaiter.GetResult = MemberCache.FindMember (type, MemberFilter.Method ("GetResult", 0,
+				ParametersCompiled.EmptyReadOnlyParameters, null),
+				BindingRestriction.InstanceOnly) as MethodSpec;
+
+			//
+			// Predefined: INotifyCompletion.OnCompleted (System.Action)
+			//
+			var nc = PredefinedTypes.INotifyCompletion;
+			awaiter.INotifyCompletion = !nc.Define () || type.ImplementsInterface (nc.TypeSpec, false);
+
+			awaiters.Add (type, awaiter);
+			return awaiter;
+		}
+
 		public override void GetCompletionStartingWith (string prefix, List<string> results)
 		{
 			var names = Evaluator.GetVarNames ();

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

@@ -378,8 +378,10 @@ namespace Mono.CSharp {
 					if (mode != LookupMode.Normal)
 						continue;
 
-					if (ts.MemberDefinition.IsImported)
+					if (ts.MemberDefinition.IsImported) {
+						ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (best);
 						ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
+					}
 
 					ctx.Module.Compiler.Report.Warning (436, 2, loc,
 						"The type `{0}' conflicts with the imported type of same name'. Ignoring the imported type definition",

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

@@ -649,7 +649,7 @@ namespace Mono.CSharp {
 			//
 			// This line is useful when debugging recorded messages
 			//
-			// Console.WriteLine ("RECORDING: {0}", msg.ToString ());
+			// Console.WriteLine ("RECORDING: {0}", msg.Text);
 
 			if (session_messages == null)
 				session_messages = new List<AbstractMessage> ();

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

@@ -853,7 +853,7 @@ namespace Mono.CSharp {
 
 				if (ec.CurrentIterator != null) {
 					Error_ReturnFromIterator (ec);
-				} else {
+				} else if (ec.ReturnType != InternalType.ErrorType) {
 					ec.Report.Error (126, loc,
 						"An object of a type convertible to `{0}' is required for the return statement",
 						ec.ReturnType.GetSignatureForError ());
@@ -2303,10 +2303,9 @@ namespace Mono.CSharp {
 
 				if (!s.Resolve (ec)) {
 					ok = false;
-					if (ec.IsInProbingMode)
-						break;
+					if (!ec.IsInProbingMode)
+						statements [ix] = new EmptyStatement (s.loc);
 
-					statements [ix] = new EmptyStatement (s.loc);
 					continue;
 				}
 
@@ -2560,12 +2559,14 @@ namespace Mono.CSharp {
 
 					if (b.Explicit == b.Explicit.ParametersBlock && b.Explicit.ParametersBlock.StateMachine != null) {
 						storey.HoistedThis = b.Explicit.ParametersBlock.StateMachine.HoistedThis;
-						break;
+
+						if (storey.HoistedThis != null)
+							break;
 					}
 				}
-
+				
 				//
-				// We are the first storey on path and this has to be hoisted
+				// We are the first storey on path and 'this' has to be hoisted
 				//
 				if (storey.HoistedThis == null) {
 					foreach (ExplicitBlock ref_block in Original.ParametersBlock.TopBlock.ThisReferencesFromChildrenBlock) {
@@ -2581,8 +2582,9 @@ namespace Mono.CSharp {
 						if (block_on_path == null)
 							continue;
 
-						if (storey.HoistedThis == null)
+						if (storey.HoistedThis == null) {
 							storey.AddCapturedThisField (ec);
+						}
 
 						for (ExplicitBlock b = ref_block; b.AnonymousMethodStorey != storey; b = b.Parent.Explicit) {
 							if (b.AnonymousMethodStorey != null) {
@@ -2605,7 +2607,7 @@ namespace Mono.CSharp {
 
 								pb.StateMachine.AddParentStoreyReference (ec, storey);
 							}
-
+							
 							b.HasCapturedVariable = true;
 						}
 					}
@@ -4190,11 +4192,17 @@ namespace Mono.CSharp {
 					constant_section = default_section;
 			} else {
 				//
-				// Store switch expression for comparission purposes
+				// Store switch expression for comparison purposes
 				//
 				value = new_expr as VariableReference;
-				if (value == null)
+				if (value == null) {
+					// Create temporary variable inside switch scope
+					var block = ec.CurrentBlock;
+					ec.CurrentBlock = Block;
 					value = TemporaryVariableReference.Create (SwitchType, ec.CurrentBlock, loc);
+					value.Resolve (ec);
+					ec.CurrentBlock = block;
+				}
 			}
 
 			bool first = true;
@@ -6126,7 +6134,7 @@ namespace Mono.CSharp {
 				if (mg != null) {
 					mg.InstanceExpression = expr;
 					Arguments args = new Arguments (0);
-					mg = mg.OverloadResolve (rc, ref args, this, OverloadResolver.Restrictions.None);
+					mg = mg.OverloadResolve (rc, ref args, this, OverloadResolver.Restrictions.ProbingOnly);
 
 					// For ambiguous GetEnumerator name warning CS0278 was reported, but Option 2 could still apply
 					if (ambiguous_getenumerator_name)

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

@@ -969,6 +969,19 @@ namespace Mono.CSharp
 		}
 	}
 
+	public class AwaiterDefinition
+	{
+		public PropertySpec IsCompleted { get; set; }
+		public MethodSpec GetResult { get; set; }
+		public bool INotifyCompletion { get; set; }
+
+		public bool IsValidPattern {
+			get {
+				return IsCompleted != null && GetResult != null && IsCompleted.HasGet;
+			}
+		}
+	}
+
 	partial class TypeManager {
 
 	/// <summary>

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

@@ -12,6 +12,7 @@
 using System;
 using System.Collections.Generic;
 using System.Text;
+using System.Linq;
 
 #if STATIC
 using MetaType = IKVM.Reflection.Type;
@@ -389,11 +390,16 @@ namespace Mono.CSharp
 			// When resolving base class of X`1 we inflate context type A`1
 			// All this happens before we even hit IFoo resolve. Without
 			// additional expansion any inside usage of A<T> would miss IFoo
-			// interface because it comes from early inflated TypeSpec
+			// interface because it comes from early inflated A`1 definition.
 			//
 			if (inflated_instances != null) {
-				foreach (var inflated in inflated_instances) {
-					inflated.Value.AddInterface (iface);
+				//
+				// Inflate only existing instances not any new instances added
+				// during AddInterface
+				//
+				var inflated_existing = inflated_instances.Values.ToArray ();
+				foreach (var inflated in inflated_existing) {
+					inflated.AddInterface (iface);
 				}
 			}