Rework gc descriptor to include size information in more cases.
[mono.git] / mcs / mcs / ecore.cs
index 60386c5864a7ab192ec5f83253c4e8ebd79d08d0..6263adab8b99b96e64fe7e943f8ea1baf4447c5c 100644 (file)
@@ -7,6 +7,7 @@
 //
 // Copyright 2001, 2002, 2003 Ximian, Inc.
 // Copyright 2003-2008 Novell, Inc.
+// Copyright 2011 Xamarin Inc.
 //
 //
 
@@ -146,6 +147,15 @@ namespace Mono.CSharp {
                        }
                }
 
+               //
+               // Returns true when the expression during Emit phase breaks stack
+               // by using await expression
+               //
+               public virtual bool ContainsEmitWithAwait ()
+               {
+                       return false;
+               }
+
                /// <summary>
                ///   Performs semantic analysis on the Expression
                /// </summary>
@@ -306,9 +316,20 @@ namespace Mono.CSharp {
                                TypeManager.CSharpName (type), name);
                }
 
-               protected static void Error_ValueAssignment (ResolveContext ec, Location loc)
+               public void Error_ValueAssignment (ResolveContext rc, Expression rhs)
                {
-                       ec.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
+                       if (rhs == EmptyExpression.LValueMemberAccess || rhs == EmptyExpression.LValueMemberOutAccess) {
+                               rc.Report.SymbolRelatedToPreviousError (type);
+                               if (rc.CurrentInitializerVariable != null) {
+                                       rc.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
+                                               type.GetSignatureForError (), GetSignatureForError ());
+                               } else {
+                                       rc.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
+                                               GetSignatureForError ());
+                               }
+                       } else {
+                               rc.Report.Error (131, loc, "The left-hand side of an assignment must be a variable, a property or an indexer");
+                       }
                }
 
                protected void Error_VoidPointerOperation (ResolveContext rc)
@@ -381,7 +402,7 @@ namespace Mono.CSharp {
                                        throw;
 
                                ec.Report.Error (584, loc, "Internal compiler error: {0}", ex.Message);
-                               return EmptyExpression.Null;    // TODO: Add location
+                               return ErrorExpression.Instance;        // TODO: Add location
                        }
                }
 
@@ -422,7 +443,7 @@ namespace Mono.CSharp {
                                        if (out_access)
                                                ec.Report.Error (1510, loc, "A ref or out argument must be an assignable variable");
                                        else
-                                               Error_ValueAssignment (ec, loc);
+                                               Error_ValueAssignment (ec, right_side);
                                }
                                return null;
                        }
@@ -472,6 +493,107 @@ namespace Mono.CSharp {
                        ec.Emit (OpCodes.Pop);
                }
 
+               //
+               // Emits the expression into temporary field variable. The method
+               // should be used for await expressions only
+               //
+               public virtual Expression EmitToField (EmitContext ec)
+               {
+                       //
+                       // This is the await prepare Emit method. When emitting code like
+                       // a + b we emit code like
+                       //
+                       // a.Emit ()
+                       // b.Emit ()
+                       // Opcodes.Add
+                       //
+                       // For await a + await b we have to interfere the flow to keep the
+                       // stack clean because await yields from the expression. The emit
+                       // then changes to
+                       //
+                       // a = a.EmitToField () // a is changed to temporary field access
+                       // b = b.EmitToField ()
+                       // a.Emit ()
+                       // b.Emit ()
+                       // Opcodes.Add
+                       //
+                       //
+                       // The idea is to emit expression and leave the stack empty with
+                       // result value still available.
+                       //
+                       // Expressions should override this default implementation when
+                       // optimized version can be provided (e.g. FieldExpr)
+                       //
+                       //
+                       // We can optimize for side-effect free expressions, they can be
+                       // emitted out of order
+                       //
+                       if (IsSideEffectFree)
+                               return this;
+
+                       bool needs_temporary = ContainsEmitWithAwait ();
+                       if (!needs_temporary)
+                               ec.EmitThis ();
+
+                       // Emit original code
+                       EmitToFieldSource (ec);
+
+                       //
+                       // Store the result to temporary field when we
+                       // cannot load `this' directly
+                       //
+                       var field = ec.GetTemporaryField (type);
+                       if (needs_temporary) {
+                               //
+                               // Create temporary local (we cannot load `this' before Emit)
+                               //
+                               var temp = ec.GetTemporaryLocal (type);
+                               ec.Emit (OpCodes.Stloc, temp);
+
+                               ec.EmitThis ();
+                               ec.Emit (OpCodes.Ldloc, temp);
+                               field.EmitAssignFromStack (ec);
+
+                               ec.FreeTemporaryLocal (temp, type);
+                       } else {
+                               field.EmitAssignFromStack (ec);
+                       }
+
+                       return field;
+               }
+
+               protected virtual void EmitToFieldSource (EmitContext ec)
+               {
+                       //
+                       // Default implementation calls Emit method
+                       //
+                       Emit (ec);
+               }
+
+               protected static void EmitExpressionsList (EmitContext ec, List<Expression> expressions)
+               {
+                       if (ec.HasSet (BuilderContext.Options.AsyncBody)) {
+                               bool contains_await = false;
+
+                               for (int i = 1; i < expressions.Count; ++i) {
+                                       if (expressions[i].ContainsEmitWithAwait ()) {
+                                               contains_await = true;
+                                               break;
+                                       }
+                               }
+
+                               if (contains_await) {
+                                       for (int i = 0; i < expressions.Count; ++i) {
+                                               expressions[i] = expressions[i].EmitToField (ec);
+                                       }
+                               }
+                       }
+
+                       for (int i = 0; i < expressions.Count; ++i) {
+                               expressions[i].Emit (ec);
+                       }
+               }
+
                /// <summary>
                ///   Protected constructor.  Only derivate types should
                ///   be able to be created
@@ -501,7 +623,7 @@ namespace Mono.CSharp {
                        return null;
                }
 
-               protected static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
+               public static MethodSpec ConstructorLookup (ResolveContext rc, TypeSpec type, ref Arguments args, Location loc)
                {
                        var ctors = MemberCache.FindMembers (type, Constructor.ConstructorName, true);
                        if (ctors == null) {
@@ -518,15 +640,11 @@ namespace Mono.CSharp {
                        }
 
                        var r = new OverloadResolver (ctors, OverloadResolver.Restrictions.NoBaseMembers, loc);
-                       var ctor = r.ResolveMember<MethodSpec> (rc, ref args);
-                       if (ctor == null)
-                               return null;
-
-                       if ((ctor.Modifiers & Modifiers.PROTECTED) != 0 && !rc.HasSet (ResolveContext.Options.BaseInitializer)) {
-                               MemberExpr.CheckProtectedMemberAccess (rc, ctor, ctor.DeclaringType, loc);
+                       if (!rc.HasSet (ResolveContext.Options.BaseInitializer)) {
+                               r.InstanceQualifier = new ConstructorInstanceQualifier (type);
                        }
 
-                       return ctor;
+                       return r.ResolveMember<MethodSpec> (rc, ref args);
                }
 
                [Flags]
@@ -558,6 +676,9 @@ namespace Mono.CSharp {
                                        if ((member.Modifiers & Modifiers.OVERRIDE) != 0 && member.Kind != MemberKind.Event)
                                                continue;
 
+                                       if ((member.Modifiers & Modifiers.BACKING_FIELD) != 0)
+                                               continue;
+
                                        if ((arity > 0 || (restrictions & MemberLookupRestrictions.ExactArity) != 0) && member.Arity != arity)
                                                continue;
 
@@ -628,6 +749,12 @@ namespace Mono.CSharp {
                        throw new NotImplementedException ();
                }
 
+               public virtual void Error_OperatorCannotBeApplied (ResolveContext rc, Location loc, string oper, TypeSpec t)
+               {
+                       rc.Report.Error (23, loc, "The `{0}' operator cannot be applied to operand of type `{1}'",
+                               oper, t.GetSignatureForError ());
+               }
+
                protected void Error_PointerInsideExpressionTree (ResolveContext ec)
                {
                        ec.Report.Error (1944, loc, "An expression tree cannot contain an unsafe pointer operation");
@@ -721,7 +848,7 @@ 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;
@@ -764,18 +891,6 @@ namespace Mono.CSharp {
                        Report.Error (214, loc, "Pointers and fixed size buffers may only be used in an unsafe context");
                }
 
-               protected void Error_CannotModifyIntermediateExpressionValue (ResolveContext ec)
-               {
-                       ec.Report.SymbolRelatedToPreviousError (type);
-                       if (ec.CurrentInitializerVariable != null) {
-                               ec.Report.Error (1918, loc, "Members of value type `{0}' cannot be assigned using a property `{1}' object initializer",
-                                       TypeManager.CSharpName (type), GetSignatureForError ());
-                       } else {
-                               ec.Report.Error (1612, loc, "Cannot modify a value type return value of `{0}'. Consider storing the value in a temporary variable",
-                                       GetSignatureForError ());
-                       }
-               }
-
                //
                // Converts `source' to an int, uint, long or ulong.
                //
@@ -891,6 +1006,11 @@ namespace Mono.CSharp {
                {
                        throw new NotImplementedException ("MakeExpression for " + GetType ());
                }
+                       
+               public virtual object Accept (StructuralVisitor visitor)
+               {
+                       return visitor.Visit (this);
+               }
        }
 
        /// <summary>
@@ -959,6 +1079,11 @@ namespace Mono.CSharp {
                        }
                }
 
+               public override bool ContainsEmitWithAwait ()
+               {
+                       return child.ContainsEmitWithAwait ();
+               }
+
                public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        Arguments args = new Arguments (2);
@@ -1741,6 +1866,17 @@ namespace Mono.CSharp {
                                        c = new ReducedConstantExpression (c, orig_expr);
                                return c;
                        }
+
+                       public override void EncodeAttributeValue (IMemberContext rc, AttributeEncoder enc, TypeSpec targetType)
+                       {
+                               //
+                               // LAMESPEC: Reduced conditional expression is allowed as an attribute argument
+                               //
+                               if (orig_expr is Conditional)
+                                       child.EncodeAttributeValue (rc, enc, targetType);
+                               else
+                                       base.EncodeAttributeValue (rc, enc, targetType);
+                       }
                }
 
                sealed class ReducedExpressionStatement : ExpressionStatement
@@ -1758,6 +1894,11 @@ namespace Mono.CSharp {
                                this.loc = orig.Location;
                        }
 
+                       public override bool ContainsEmitWithAwait ()
+                       {
+                               return stm.ContainsEmitWithAwait ();
+                       }
+
                        public override Expression CreateExpressionTree (ResolveContext ec)
                        {
                                return orig_expr.CreateExpressionTree (ec);
@@ -1800,6 +1941,11 @@ namespace Mono.CSharp {
 
                #endregion
 
+               public override bool ContainsEmitWithAwait ()
+               {
+                       return expr.ContainsEmitWithAwait ();
+               }
+
                //
                // Creates fully resolved expression switcher
                //
@@ -1883,6 +2029,11 @@ namespace Mono.CSharp {
                        this.loc = expr.Location;
                }
 
+               public override bool ContainsEmitWithAwait ()
+               {
+                       return expr.ContainsEmitWithAwait ();
+               }
+
                public override Expression CreateExpressionTree (ResolveContext rc)
                {
                        return expr.CreateExpressionTree (rc);
@@ -1940,6 +2091,11 @@ namespace Mono.CSharp {
                        target.expr = expr.Clone (clonectx);
                }
 
+               public override bool ContainsEmitWithAwait ()
+               {
+                       return expr.ContainsEmitWithAwait ();
+               }
+
                public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        throw new NotSupportedException ("ET");
@@ -2078,9 +2234,16 @@ namespace Mono.CSharp {
                        return new SimpleName (Name, targs, loc);
                }
 
-               protected override Expression DoResolve (ResolveContext ec)
+               protected override Expression DoResolve (ResolveContext rc)
                {
-                       return SimpleNameResolve (ec, null, false);
+                       var e = SimpleNameResolve (rc, null, false);
+
+                       var fe = e as FieldExpr;
+                       if (fe != null) {
+                               fe.VerifyAssignedStructField (rc, null);
+                       }
+
+                       return e;
                }
 
                public override Expression DoResolveLValue (ResolveContext ec, Expression right_side)
@@ -2100,7 +2263,6 @@ namespace Mono.CSharp {
                                }
                        }
 
-                       // MSAF
                        var retval = ctx.LookupNamespaceOrType (Name, Arity, LookupMode.IgnoreAccessibility, loc);
                        if (retval != null) {
                                ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (retval.Type);
@@ -2370,6 +2532,11 @@ namespace Mono.CSharp {
                        //if (ec.CurrentBlock == null || ec.CurrentBlock.CheckInvariantMeaningInBlock (Name, e, Location))
                        return e;
                }
+               
+               public override object Accept (StructuralVisitor visitor)
+               {
+                       return visitor.Visit (this);
+               }
        }
 
        /// <summary>
@@ -2384,6 +2551,11 @@ namespace Mono.CSharp {
                        // resolved to different type
                }
 
+               public override bool ContainsEmitWithAwait ()
+               {
+                       return false;
+               }
+
                public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        throw new NotSupportedException ("ET");
@@ -2494,7 +2666,7 @@ namespace Mono.CSharp {
        ///   This class denotes an expression which evaluates to a member
        ///   of a struct or a class.
        /// </summary>
-       public abstract class MemberExpr : Expression
+       public abstract class MemberExpr : Expression, OverloadResolver.IInstanceQualifier
        {
                //
                // An instance expression associated with this member, if it's a
@@ -2534,6 +2706,12 @@ namespace Mono.CSharp {
                        get;
                }
 
+               TypeSpec OverloadResolver.IInstanceQualifier.InstanceType {
+                       get {
+                               return InstanceExpression.Type;
+                       }
+               }
+
                //
                // Converts best base candidate for virtual method starting from QueriedBaseType
                //
@@ -2598,32 +2776,46 @@ namespace Mono.CSharp {
                        return method;
                }
 
-               protected void CheckProtectedMemberAccess<T> (ResolveContext rc, T member) where T : MemberSpec
+               protected void CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
                {
                        if (InstanceExpression == null)
                                return;
 
                        if ((member.Modifiers & Modifiers.PROTECTED) != 0 && !(InstanceExpression is This)) {
-                               CheckProtectedMemberAccess (rc, member, InstanceExpression.Type, loc);
+                               if (!CheckProtectedMemberAccess (rc, member, InstanceExpression.Type)) {
+                                       Error_ProtectedMemberAccess (rc, member, InstanceExpression.Type, loc);
+                               }
                        }
                }
 
-               public static void CheckProtectedMemberAccess<T> (ResolveContext rc, T member, TypeSpec qualifier, Location loc) where T : MemberSpec
+               bool OverloadResolver.IInstanceQualifier.CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
+               {
+                       if (InstanceExpression == null)
+                               return true;
+
+                       return InstanceExpression is This || CheckProtectedMemberAccess (rc, member, InstanceExpression.Type);
+               }
+
+               public static bool CheckProtectedMemberAccess<T> (ResolveContext rc, T member, TypeSpec qualifier) where T : MemberSpec
                {
                        var ct = rc.CurrentType;
                        if (ct == qualifier)
-                               return;
+                               return true;
 
                        if ((member.Modifiers & Modifiers.INTERNAL) != 0 && member.DeclaringType.MemberDefinition.IsInternalAsPublic (ct.MemberDefinition.DeclaringAssembly))
-                               return;
+                               return true;
 
                        qualifier = qualifier.GetDefinition ();
                        if (ct != qualifier && !IsSameOrBaseQualifier (ct, qualifier)) {
-                               rc.Report.SymbolRelatedToPreviousError (member);
-                               rc.Report.Error (1540, loc,
-                                       "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
-                                       member.GetSignatureForError (), qualifier.GetSignatureForError (), ct.GetSignatureForError ());
+                               return false;
                        }
+
+                       return true;
+               }
+
+               public override bool ContainsEmitWithAwait ()
+               {
+                       return InstanceExpression != null && InstanceExpression.ContainsEmitWithAwait ();
                }
 
                static bool IsSameOrBaseQualifier (TypeSpec type, TypeSpec qtype)
@@ -2671,6 +2863,14 @@ namespace Mono.CSharp {
                        rc.Report.Error (205, loc, "Cannot call an abstract base member `{0}'", name);
                }
 
+               public static void Error_ProtectedMemberAccess (ResolveContext rc, MemberSpec member, TypeSpec qualifier, Location loc)
+               {
+                       rc.Report.SymbolRelatedToPreviousError (member);
+                       rc.Report.Error (1540, loc,
+                               "Cannot access protected member `{0}' via a qualifier of type `{1}'. The qualifier must be of type `{2}' or derived from it",
+                               member.GetSignatureForError (), qualifier.GetSignatureForError (), rc.CurrentType.GetSignatureForError ());
+               }
+
                //
                // Implements identicial simple name and type-name
                //
@@ -2732,6 +2932,7 @@ namespace Mono.CSharp {
                                                        "An object reference is required to access non-static member `{0}'",
                                                        GetSignatureForError ());
 
+                                       InstanceExpression = new CompilerGeneratedThis (type, loc).Resolve (rc);
                                        return false;
                                }
 
@@ -2742,7 +2943,7 @@ namespace Mono.CSharp {
                                }
 
                                InstanceExpression = new This (loc);
-                               if (this is FieldExpr && rc.CurrentType.IsStruct) {
+                               if (this is FieldExpr && rc.CurrentBlock.ParametersBlock.TopBlock.ThisVariable != null) {
                                        using (rc.Set (ResolveContext.Options.OmitStructFlowAnalysis)) {
                                                InstanceExpression = InstanceExpression.Resolve (rc);
                                        }
@@ -2773,7 +2974,7 @@ namespace Mono.CSharp {
                        // the expression is not field expression which is the only
                        // expression which can use uninitialized this
                        //
-                       if (InstanceExpression is This && !(this is FieldExpr) && rc.CurrentType.IsStruct) {
+                       if (InstanceExpression is This && !(this is FieldExpr) && rc.CurrentBlock.ParametersBlock.TopBlock.ThisVariable != null) {
                                ((This)InstanceExpression).CheckStructThisDefiniteAssignment (rc);
                        }
 
@@ -2781,9 +2982,6 @@ namespace Mono.CSharp {
                        // Additional checks for l-value member access
                        //
                        if (rhs != null) {
-                               //
-                               // TODO: It should be recursive but that would break csc compatibility
-                               //
                                if (InstanceExpression is UnboxCast) {
                                        rc.Report.Error (445, InstanceExpression.Location, "Cannot modify the result of an unboxing conversion");
                                }
@@ -2810,6 +3008,8 @@ namespace Mono.CSharp {
                                if (InstanceExpression is IMemoryLocation) {
                                        ((IMemoryLocation) InstanceExpression).AddressOf (ec, AddressOp.Load);
                                } else {
+                                       // Cannot release the temporary variable when its address
+                                       // is required to be on stack for any parent
                                        LocalTemporary t = new LocalTemporary (instance_type);
                                        InstanceExpression.Emit (ec);
                                        t.Store (ec);
@@ -2830,18 +3030,57 @@ namespace Mono.CSharp {
                public abstract void SetTypeArguments (ResolveContext ec, TypeArguments ta);
        }
 
+       public class ExtensionMethodCandidates
+       {
+               NamespaceContainer container;
+               Namespace ns;
+               IList<MethodSpec> methods;
+
+               public ExtensionMethodCandidates (IList<MethodSpec> methods, NamespaceContainer nsContainer)
+                       : this (methods, nsContainer, null)
+               {
+               }
+
+               public ExtensionMethodCandidates (IList<MethodSpec> methods, NamespaceContainer nsContainer, Namespace ns)
+               {
+                       this.methods = methods;
+                       this.container = nsContainer;
+                       this.ns = ns;
+               }
+
+               public NamespaceContainer Container {
+                       get {
+                               return container;
+                       }
+               }
+
+               public bool HasUninspectedMembers { get; set; }
+
+               public Namespace Namespace {
+                       get {
+                               return ns;
+                       }
+               }
+
+               public IList<MethodSpec> Methods {
+                       get {
+                               return methods;
+                       }
+               }
+       }
+
        // 
        // Represents a group of extension method candidates for whole namespace
        // 
        class ExtensionMethodGroupExpr : MethodGroupExpr, OverloadResolver.IErrorHandler
        {
-               NamespaceContainer namespace_entry;
+               ExtensionMethodCandidates candidates;
                public readonly Expression ExtensionExpression;
 
-               public ExtensionMethodGroupExpr (IList<MethodSpec> list, NamespaceContainer n, Expression extensionExpr, Location l)
-                       : base (list.Cast<MemberSpec>().ToList (), extensionExpr.Type, l)
+               public ExtensionMethodGroupExpr (ExtensionMethodCandidates candidates, Expression extensionExpr, Location loc)
+                       : base (candidates.Methods.Cast<MemberSpec>().ToList (), extensionExpr.Type, loc)
                {
-                       this.namespace_entry = n;
+                       this.candidates = candidates;
                        this.ExtensionExpression = extensionExpr;
                }
 
@@ -2849,21 +3088,55 @@ namespace Mono.CSharp {
                        get { return true; }
                }
 
+               //
+               // For extension methodgroup we are not looking for base members but parent
+               // namespace extension methods
+               //
                public override IList<MemberSpec> GetBaseMembers (TypeSpec baseType)
                {
-                       if (namespace_entry == null)
+                       // TODO: candidates are null only when doing error reporting, that's
+                       // incorrect. We have to discover same extension methods in error mode
+                       if (candidates == null)
                                return null;
 
+                       int arity = type_arguments == null ? 0 : type_arguments.Count;
+
                        //
-                       // For extension methodgroup we are not looking for base members but parent
-                       // namespace extension methods
+                       // Here we try to resume the search for extension method at the point
+                       // where the last bunch of candidates was found. It's more tricky than
+                       // it seems as we have to check both namespace containers and namespace
+                       // in correct order.
                        //
-                       int arity = type_arguments == null ? 0 : type_arguments.Count;
-                       var found = namespace_entry.LookupExtensionMethod (DeclaringType, Name, arity, ref namespace_entry);
-                       if (found == null)
+                       // Consider:
+                       // 
+                       // namespace A {
+                       //      using N1;
+                       //  namespace B.C.D {
+                       //              <our first search found candidates in A.B.C.D
+                       //  }
+                       // }
+                       //
+                       // In the example above namespace A.B.C.D, A.B.C and A.B have to be
+                       // checked before we hit A.N1 using
+                       //
+                       if (candidates.Namespace == null) {
+                               Namespace scope;
+                               var methods = candidates.Container.NS.LookupExtensionMethod (candidates.Container, ExtensionExpression.Type, Name, arity, out scope);
+                               if (methods != null) {
+                                       candidates = new ExtensionMethodCandidates (null, candidates.Container, scope);
+                                       return methods.Cast<MemberSpec> ().ToList ();
+                               }
+                       }
+
+                       var ns_container = candidates.HasUninspectedMembers ? candidates.Container : candidates.Container.Parent;
+                       if (ns_container == null)
                                return null;
 
-                       return found.Cast<MemberSpec> ().ToList ();
+                       candidates = ns_container.LookupExtensionMethod (ExtensionExpression.Type, Name, arity);
+                       if (candidates == null)
+                               return null;
+
+                       return candidates.Methods.Cast<MemberSpec> ().ToList ();
                }
 
                public override MethodGroupExpr LookupExtensionMethod (ResolveContext rc)
@@ -3072,7 +3345,9 @@ namespace Mono.CSharp {
                
                public void EmitCall (EmitContext ec, Arguments arguments)
                {
-                       Invocation.EmitCall (ec, InstanceExpression, best_candidate, arguments, loc);                   
+                       var call = new CallEmitter ();
+                       call.InstanceExpression = InstanceExpression;
+                       call.Emit (ec, best_candidate, arguments, loc);                 
                }
 
                public override void Error_ValueCannotBeConverted (ResolveContext ec, Location loc, TypeSpec target, bool expl)
@@ -3114,6 +3389,7 @@ namespace Mono.CSharp {
                        var r = new OverloadResolver (Methods, type_arguments, restr, loc);
                        if ((restr & OverloadResolver.Restrictions.NoBaseMembers) == 0) {
                                r.BaseMembersProvider = this;
+                               r.InstanceQualifier = this;
                        }
 
                        if (cerrors != null)
@@ -3142,8 +3418,6 @@ namespace Mono.CSharp {
                                }
 
                                ResolveInstanceExpression (ec, null);
-                               if (InstanceExpression != null)
-                                       CheckProtectedMemberAccess (ec, best_candidate);
                        }
 
                        var base_override = CandidateToBaseOverride (ec, best_candidate);
@@ -3197,12 +3471,11 @@ namespace Mono.CSharp {
                                return null;
 
                        int arity = type_arguments == null ? 0 : type_arguments.Count;
-                       NamespaceContainer methods_scope = null;
-                       var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity, ref methods_scope);
+                       var methods = rc.LookupExtensionMethod (InstanceExpression.Type, Methods[0].Name, arity);
                        if (methods == null)
                                return null;
 
-                       var emg = new ExtensionMethodGroupExpr (methods, methods_scope, InstanceExpression, loc);
+                       var emg = new ExtensionMethodGroupExpr (methods, InstanceExpression, loc);
                        emg.SetTypeArguments (rc, type_arguments);
                        return emg;
                }
@@ -3210,6 +3483,22 @@ namespace Mono.CSharp {
                #endregion
        }
 
+       struct ConstructorInstanceQualifier : OverloadResolver.IInstanceQualifier
+       {
+               public ConstructorInstanceQualifier (TypeSpec type)
+                       : this ()
+               {
+                       InstanceType = type;
+               }
+
+               public TypeSpec InstanceType { get; private set; }
+
+               public bool CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member)
+               {
+                       return MemberExpr.CheckProtectedMemberAccess (rc, member, InstanceType);
+               }
+       }
+
        public struct OverloadResolver
        {
                [Flags]
@@ -3238,6 +3527,12 @@ namespace Mono.CSharp {
                        bool TypeInferenceFailed (ResolveContext rc, MemberSpec best);
                }
 
+               public interface IInstanceQualifier
+               {
+                       TypeSpec InstanceType { get; }
+                       bool CheckProtectedMemberAccess (ResolveContext rc, MemberSpec member);
+               }
+
                sealed class NoBaseMembers : IBaseMembersProvider
                {
                        public static readonly IBaseMembersProvider Instance = new NoBaseMembers ();
@@ -3277,6 +3572,7 @@ namespace Mono.CSharp {
                TypeArguments type_arguments;
                IBaseMembersProvider base_provider;
                IErrorHandler custom_errors;
+               IInstanceQualifier instance_qualifier;
                Restrictions restrictions;
                MethodGroupExpr best_candidate_extension_group;
                TypeSpec best_candidate_return_type;
@@ -3354,6 +3650,15 @@ namespace Mono.CSharp {
                        }
                }
 
+               public IInstanceQualifier InstanceQualifier {
+                       get {
+                               return instance_qualifier;
+                       }
+                       set {
+                               instance_qualifier = value;
+                       }
+               }
+
                bool IsProbingOnly {
                        get {
                                return (restrictions & Restrictions.ProbingOnly) != 0;
@@ -3428,16 +3733,16 @@ namespace Mono.CSharp {
                                // better conversion is performed between underlying types Y1 and Y2
                                //
                                if (p.IsGenericTask || q.IsGenericTask) {
-                                       if (p.IsGenericTask != q.IsGenericTask) {
-                                               return 0;
-                                       }
-
                                        var async_am = a.Expr as AnonymousMethodExpression;
-                                       if (async_am == null || !async_am.IsAsync)
-                                               return 0;
+                                       if (async_am != null && async_am.Block.IsAsync) {
 
-                                       q = q.TypeArguments[0];
-                                       p = p.TypeArguments[0];
+                                               if (p.IsGenericTask != q.IsGenericTask) {
+                                                       return 0;
+                                               }
+
+                                               q = q.TypeArguments[0];
+                                               p = p.TypeArguments[0];
+                                       }
                                }
 
                                //
@@ -3935,7 +4240,7 @@ namespace Mono.CSharp {
                                        // if the type matches
                                        //
                                        Expression e = pd.FixedParameters[i].DefaultValue;
-                                       if (!(e is Constant) || e.Type.IsGenericOrParentIsGeneric) {
+                                       if (!(e is Constant) || e.Type.IsGenericOrParentIsGeneric || e.Type.IsGenericParameter) {
                                                //
                                                // LAMESPEC: No idea what the exact rules are for System.Reflection.Missing.Value instead of null
                                                //
@@ -3969,9 +4274,11 @@ namespace Mono.CSharp {
                                                //
                                                // Indentity, implicit reference or boxing conversion must exist for the extension parameter
                                                //
+                                               // LAMESPEC: or implicit type parameter conversion
+                                               //
                                                var at = a.Type;
                                                if (at == pt || TypeSpecComparer.IsEqual (at, pt) ||
-                                                       Convert.ImplicitReferenceConversionExists (at, pt) ||
+                                                       Convert.ImplicitReferenceConversionExists (at, pt, false) ||
                                                        Convert.ImplicitBoxingConversion (null, at, pt) != null) {
                                                        score = 0;
                                                        continue;
@@ -4106,7 +4413,10 @@ namespace Mono.CSharp {
 
                        var ac_p = p as ArrayContainer;
                        if (ac_p != null) {
-                               var ac_q = ((ArrayContainer) q);
+                               var ac_q = q as ArrayContainer;
+                               if (ac_q == null)
+                                       return null;
+
                                TypeSpec specific = MoreSpecific (ac_p.Element, ac_q.Element);
                                if (specific == ac_p.Element)
                                        return p;
@@ -4181,6 +4491,11 @@ namespace Mono.CSharp {
 
                                                                if (rc.IsRuntimeBinder && !member.DeclaringType.IsAccessible (rc))
                                                                        continue;
+
+                                                               if ((member.Modifiers & (Modifiers.PROTECTED | Modifiers.STATIC)) == Modifiers.PROTECTED &&
+                                                                       instance_qualifier != null && !instance_qualifier.CheckProtectedMemberAccess (rc, member)) {
+                                                                       continue;
+                                                               }
                                                        }
 
                                                        IParametersMember pm = member as IParametersMember;
@@ -4320,6 +4635,9 @@ namespace Mono.CSharp {
                                if (error_mode)
                                        break;
 
+                               if (lambda_conv_msgs != null && !lambda_conv_msgs.IsEmpty)
+                                       break;
+
                                lambda_conv_msgs = null;
                                error_mode = true;
                        }
@@ -4482,6 +4800,12 @@ namespace Mono.CSharp {
                                        return;
                        }
 
+
+                       if ((best_candidate.Modifiers & (Modifiers.PROTECTED | Modifiers.STATIC)) == Modifiers.PROTECTED &&
+                               InstanceQualifier != null && !InstanceQualifier.CheckProtectedMemberAccess (rc, best_candidate)) {
+                               MemberExpr.Error_ProtectedMemberAccess (rc, best_candidate, InstanceQualifier.InstanceType, loc);
+                       }
+
                        //
                        // For candidates which match on parameters count report more details about incorrect arguments
                        //
@@ -4756,10 +5080,11 @@ namespace Mono.CSharp {
                }
        }
 
-       /// <summary>
-       ///   Fully resolved expression that evaluates to a Field
-       /// </summary>
-       public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference {
+       //
+       // Fully resolved expression that references a Field
+       //
+       public class FieldExpr : MemberExpr, IDynamicAssign, IMemoryLocation, IVariableReference
+       {
                protected FieldSpec spec;
                VariableInfo variable_info;
                
@@ -4833,7 +5158,7 @@ namespace Mono.CSharp {
 
                public override string GetSignatureForError ()
                {
-                       return TypeManager.GetFullNameSignature (spec);
+                       return spec.GetSignatureForError ();
                }
 
                public bool IsMarshalByRefAccess (ResolveContext rc)
@@ -4847,8 +5172,9 @@ namespace Mono.CSharp {
                public void SetHasAddressTaken ()
                {
                        IVariableReference vr = InstanceExpression as IVariableReference;
-                       if (vr != null)
+                       if (vr != null) {
                                vr.SetHasAddressTaken ();
+                       }
                }
 
                public override Expression CreateExpressionTree (ResolveContext ec)
@@ -4913,7 +5239,7 @@ namespace Mono.CSharp {
                        IVariableReference var = InstanceExpression as IVariableReference;
 
                        if (lvalue_instance && var != null && var.VariableInfo != null) {
-                               var.VariableInfo.SetFieldAssigned (ec, Name);
+                               var.VariableInfo.SetStructFieldAssigned (ec, Name);
                        }
                        
                        if (fb != null) {
@@ -4929,22 +5255,47 @@ namespace Mono.CSharp {
                                } else if (var != null && var.IsHoisted) {
                                        AnonymousMethodExpression.Error_AddressOfCapturedVar (ec, var, loc);
                                }
-                               
+
                                return new FixedBufferPtr (this, fb.ElementType, loc).Resolve (ec);
                        }
 
+                       //
+                       // Set flow-analysis variable info for struct member access. It will be check later
+                       // for precise error reporting
+                       //
+                       if (var != null && var.VariableInfo != null && InstanceExpression.Type.IsStruct) {
+                               variable_info = var.VariableInfo.GetStructFieldInfo (Name);
+                               if (rhs != null && variable_info != null)
+                                       variable_info.SetStructFieldAssigned (ec, Name);
+                       }
+
                        eclass = ExprClass.Variable;
+                       return this;
+               }
 
-                       // If the instance expression is a local variable or parameter.
-                       if (var == null || var.VariableInfo == null)
-                               return this;
+               public void VerifyAssignedStructField (ResolveContext rc, Expression rhs)
+               {
+                       var fe = this;
 
-                       VariableInfo vi = var.VariableInfo;
-                       if (!vi.IsFieldAssigned (ec, Name, loc))
-                               return null;
+                       do {
+                               var var = fe.InstanceExpression as IVariableReference;
+                               if (var != null) {
+                                       var vi = var.VariableInfo;
 
-                       variable_info = vi.GetSubStruct (Name);
-                       return this;
+                                       if (vi != null && !vi.IsStructFieldAssigned (rc, fe.Name) && (rhs == null || !fe.type.IsStruct)) {
+                                               if (rhs != null) {
+                                                       rc.Report.Warning (1060, 1, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
+                                               } else {
+                                                       rc.Report.Error (170, fe.loc, "Use of possibly unassigned field `{0}'", fe.Name);
+                                               }
+
+                                               return;
+                                       }
+                               }
+
+                               fe = fe.InstanceExpression as FieldExpr;
+
+                       } while (fe != null);
                }
 
                static readonly int [] codes = {
@@ -5066,10 +5417,7 @@ 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 ();
                        
@@ -5108,23 +5456,27 @@ namespace Mono.CSharp {
                        }
                }
 
-               public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
+               public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
                {
-                       var await_expr = source as Await;
-                       if (await_expr != null) {
-                               //
-                               // Await is not ordinary expression (it contains jump), hence the usual flow cannot be used
-                               // to emit instance load before expression
-                               //
-                               await_expr.EmitAssign (ec, this);
-                       } else {
-                               prepared = prepare_for_load && !(source is DynamicExpressionStatement);
-                               if (IsInstance)
-                                       EmitInstance (ec, prepared);
+                       bool has_await_source = ec.HasSet (BuilderContext.Options.AsyncBody) && source.ContainsEmitWithAwait ();
+                       if (isCompound && !(source is DynamicExpressionStatement)) {
+                               if (has_await_source) {
+                                       if (IsInstance)
+                                               InstanceExpression = InstanceExpression.EmitToField (ec);
+                               } else {
+                                       prepared = true;
+                               }
+                       }
 
-                               source.Emit (ec);
+                       if (IsInstance) {
+                               if (has_await_source)
+                                       source = source.EmitToField (ec);
+
+                               EmitInstance (ec, prepared);
                        }
 
+                       source.Emit (ec);
+
                        if (leave_copy) {
                                ec.Emit (OpCodes.Dup);
                                if (!IsStatic) {
@@ -5150,6 +5502,18 @@ namespace Mono.CSharp {
                        }
                }
 
+               //
+               // Emits store to field with prepared values on stack
+               //
+               public void EmitAssignFromStack (EmitContext ec)
+               {
+                       if (IsStatic) {
+                               ec.Emit (OpCodes.Stsfld, spec);
+                       } else {
+                               ec.Emit (OpCodes.Stfld, spec);
+                       }
+               }
+
                public override void Emit (EmitContext ec)
                {
                        Emit (ec, false);
@@ -5187,12 +5551,12 @@ namespace Mono.CSharp {
                        } else
                                need_copy = false;
                        
-                       if (need_copy){
-                               LocalBuilder local;
+                       if (need_copy) {
                                Emit (ec);
-                               local = ec.DeclareLocal (type, false);
-                               ec.Emit (OpCodes.Stloc, local);
-                               ec.Emit (OpCodes.Ldloca, local);
+                               var temp = ec.GetTemporaryLocal (type);
+                               ec.Emit (OpCodes.Stloc, temp);
+                               ec.Emit (OpCodes.Ldloca, temp);
+                               ec.FreeTemporaryLocal (temp, type);
                                return;
                        }
 
@@ -5229,14 +5593,13 @@ namespace Mono.CSharp {
        }
 
        
-       /// <summary>
-       ///   Expression that evaluates to a Property.  The Assign class
-       ///   might set the `Value' expression if we are in an assignment.
-       ///
-       ///   This is not an LValue because we need to re-write the expression, we
-       ///   can not take data from the stack and store it.  
-       /// </summary>
-       class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
+       //
+       // Expression that evaluates to a Property.
+       //
+       // This is not an LValue because we need to re-write the expression. We
+       // can not take data from the stack and store it.
+       //
+       sealed class PropertyExpr : PropertyOrIndexerExpr<PropertySpec>
        {
                public PropertyExpr (PropertySpec spec, Location l)
                        : base (l)
@@ -5247,6 +5610,14 @@ namespace Mono.CSharp {
 
                #region Properties
 
+               protected override Arguments Arguments {
+                       get {
+                               return null;
+                       }
+                       set {
+                       }
+               }
+
                protected override TypeSpec DeclaringType {
                        get {
                                return best_candidate.DeclaringType;
@@ -5279,6 +5650,14 @@ namespace Mono.CSharp {
 
                #endregion
 
+               public static PropertyExpr CreatePredefined (PropertySpec spec, Location loc)
+               {
+                       return new PropertyExpr (spec, loc) {
+                               Getter = spec.Get,
+                               Setter = spec.Set
+                       };
+               }
+
                public override Expression CreateExpressionTree (ResolveContext ec)
                {
                        Arguments args;
@@ -5297,8 +5676,9 @@ namespace Mono.CSharp {
                        return CreateExpressionFactoryCall (ec, "Property", args);
                }
 
-               public Expression CreateSetterTypeOfExpression ()
+               public Expression CreateSetterTypeOfExpression (ResolveContext rc)
                {
+                       DoResolveLValue (rc, null);
                        return new TypeOfMethod (Setter, loc);
                }
 
@@ -5347,36 +5727,41 @@ namespace Mono.CSharp {
                        // Special case: length of single dimension array property is turned into ldlen
                        //
                        if (IsSingleDimensionalArrayLength ()) {
-                               if (!prepared)
-                                       EmitInstance (ec, false);
+                               EmitInstance (ec, false);
                                ec.Emit (OpCodes.Ldlen);
                                ec.Emit (OpCodes.Conv_I4);
                                return;
                        }
 
-                       Invocation.EmitCall (ec, InstanceExpression, Getter, null, loc, prepared, false);
-                       
-                       if (leave_copy) {
-                               ec.Emit (OpCodes.Dup);
-                               if (!IsStatic) {
-                                       temp = new LocalTemporary (this.Type);
-                                       temp.Store (ec);
-                               }
-                       }
+                       base.Emit (ec, leave_copy);
                }
 
-               public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
+               public override void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
                {
                        Arguments args;
+                       LocalTemporary await_source_arg = null;
 
-                       if (prepare_for_load && !(source is DynamicExpressionStatement)) {
-                               args = new Arguments (0);
-                               prepared = true;
+                       if (isCompound && !(source is DynamicExpressionStatement)) {
+                               emitting_compound_assignment = true;
                                source.Emit (ec);
-                               
-                               if (leave_copy) {
-                                       ec.Emit (OpCodes.Dup);
-                                       if (!IsStatic) {
+
+                               if (has_await_arguments) {
+                                       await_source_arg = new LocalTemporary (Type);
+                                       await_source_arg.Store (ec);
+
+                                       args = new Arguments (1);
+                                       args.Add (new Argument (await_source_arg));
+
+                                       if (leave_copy) {
+                                               temp = await_source_arg;
+                                       }
+
+                                       has_await_arguments = false;
+                               } else {
+                                       args = null;
+
+                                       if (leave_copy) {
+                                               ec.Emit (OpCodes.Dup);
                                                temp = new LocalTemporary (this.Type);
                                                temp.Store (ec);
                                        }
@@ -5394,12 +5779,23 @@ namespace Mono.CSharp {
                                }
                        }
 
-                       Invocation.EmitCall (ec, InstanceExpression, Setter, args, loc, false, prepared);
-                       
+                       emitting_compound_assignment = false;
+
+                       var call = new CallEmitter ();
+                       call.InstanceExpression = InstanceExpression;
+                       if (args == null)
+                               call.InstanceExpressionOnStack = true;
+
+                       call.Emit (ec, Setter, args, loc);
+
                        if (temp != null) {
                                temp.Emit (ec);
                                temp.Release (ec);
                        }
+
+                       if (await_source_arg != null) {
+                               await_source_arg.Release (ec);
+                       }
                }
 
                protected override Expression OverloadResolve (ResolveContext rc, Expression right_side)
@@ -5437,7 +5833,8 @@ namespace Mono.CSharp {
                protected T best_candidate;
 
                protected LocalTemporary temp;
-               protected bool prepared;
+               protected bool emitting_compound_assignment;
+               protected bool has_await_arguments;
 
                protected PropertyOrIndexerExpr (Location l)
                {
@@ -5446,6 +5843,8 @@ namespace Mono.CSharp {
 
                #region Properties
 
+               protected abstract Arguments Arguments { get; set; }
+
                public MethodSpec Getter {
                        get {
                                return getter;
@@ -5499,7 +5898,7 @@ namespace Mono.CSharp {
 
                        // if the property/indexer returns a value type, and we try to set a field in it
                        if (right_side == EmptyExpression.LValueMemberAccess || right_side == EmptyExpression.LValueMemberOutAccess) {
-                               Error_CannotModifyIntermediateExpressionValue (ec);
+                               Error_ValueAssignment (ec, right_side);
                        }
 
                        if (eclass == ExprClass.Unresolved) {
@@ -5520,14 +5919,43 @@ namespace Mono.CSharp {
                //
                // Implements the IAssignMethod interface for assignments
                //
-               public abstract void Emit (EmitContext ec, bool leave_copy);
-               public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load);
+               public virtual void Emit (EmitContext ec, bool leave_copy)
+               {
+                       var call = new CallEmitter ();
+                       call.InstanceExpression = InstanceExpression;
+                       if (has_await_arguments)
+                               call.HasAwaitArguments = true;
+                       else
+                               call.DuplicateArguments = emitting_compound_assignment;
+
+                       call.Emit (ec, Getter, Arguments, loc);
+
+                       if (call.HasAwaitArguments) {
+                               InstanceExpression = call.InstanceExpression;
+                               Arguments = call.EmittedArguments;
+                               has_await_arguments = true;
+                       }
+
+                       if (leave_copy) {
+                               ec.Emit (OpCodes.Dup);
+                               temp = new LocalTemporary (Type);
+                               temp.Store (ec);
+                       }
+               }
+
+               public abstract void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound);
 
                public override void Emit (EmitContext ec)
                {
                        Emit (ec, false);
                }
 
+               protected override void EmitToFieldSource (EmitContext ec)
+               {
+                       has_await_arguments = true;
+                       Emit (ec, false);
+               }
+
                public abstract SLE.Expression MakeAssignExpression (BuilderContext ctx, Expression source);
 
                protected abstract Expression OverloadResolve (ResolveContext rc, Expression right_side);
@@ -5716,14 +6144,17 @@ namespace Mono.CSharp {
                        throw new NotImplementedException ();
                }
 
-               public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool prepare_for_load)
+               public void EmitAssign (EmitContext ec, Expression source, bool leave_copy, bool isCompound)
                {
-                       if (leave_copy || !prepare_for_load)
+                       if (leave_copy || !isCompound)
                                throw new NotImplementedException ("EventExpr::EmitAssign");
 
                        Arguments args = new Arguments (1);
                        args.Add (new Argument (source));
-                       Invocation.EmitCall (ec, InstanceExpression, op, args, loc);
+
+                       var call = new CallEmitter ();
+                       call.InstanceExpression = InstanceExpression;
+                       call.Emit (ec, op, args, loc);
                }
 
                #endregion
@@ -5810,20 +6241,15 @@ namespace Mono.CSharp {
                        return new TemporaryVariableReference (li, loc);
                }
 
-               public override Expression CreateExpressionTree (ResolveContext ec)
-               {
-                       throw new NotSupportedException ("ET");
-               }
-
                protected override Expression DoResolve (ResolveContext ec)
                {
                        eclass = ExprClass.Variable;
 
                        //
                        // Don't capture temporary variables except when using
-                       // iterator redirection
+                       // state machine redirection
                        //
-                       if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.IsIterator && ec.IsVariableCapturingRequired) {
+                       if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod is StateMachineInitializer && ec.IsVariableCapturingRequired) {
                                AnonymousMethodStorey storey = li.Block.Explicit.CreateAnonymousMethodStorey (ec);
                                storey.CaptureLocalVariable (ec, li);
                        }
@@ -5877,7 +6303,11 @@ namespace Mono.CSharp {
                }
 
                public override VariableInfo VariableInfo {
-                       get { throw new NotImplementedException (); }
+                       get { return null; }
+               }
+
+               public override void VerifyAssigned (ResolveContext rc)
+               {
                }
        }