Merge pull request #418 from LogosBible/bug6403
[mono.git] / mcs / mcs / statement.cs
index 94db9af85fc3cc5b872c78027367b880ceebd243..e6cdf85bd34ab17c64b4fa00ffc5c011b899948f 100644 (file)
@@ -68,6 +68,10 @@ namespace Mono.CSharp {
                {
                        ec.Mark (loc);
                        DoEmit (ec);
+
+                       if (ec.StatementEpilogue != null) {
+                               ec.EmitEpilogue ();
+                       }
                }
 
                //
@@ -277,11 +281,16 @@ namespace Mono.CSharp {
                public Expression expr;
                public Statement  EmbeddedStatement;
 
-               public Do (Statement statement, BooleanExpression bool_expr, Location l)
+               public Do (Statement statement, BooleanExpression bool_expr, Location doLocation, Location whileLocation)
                {
                        expr = bool_expr;
                        EmbeddedStatement = statement;
-                       loc = l;
+                       loc = doLocation;
+                       WhileLocation = whileLocation;
+               }
+
+               public Location WhileLocation {
+                       get; private set;
                }
 
                public override bool Resolve (BlockContext ec)
@@ -327,17 +336,21 @@ namespace Mono.CSharp {
                        EmbeddedStatement.Emit (ec);
                        ec.MarkLabel (ec.LoopBegin);
 
+                       // Mark start of while condition
+                       ec.Mark (WhileLocation);
+
                        //
                        // Dead code elimination
                        //
-                       if (expr is Constant){
+                       if (expr is Constant) {
                                bool res = !((Constant) expr).IsDefaultValue;
 
                                expr.EmitSideEffect (ec);
                                if (res)
-                                       ec.Emit (OpCodes.Br, loop); 
-                       } else
+                                       ec.Emit (OpCodes.Br, loop);
+                       } else {
                                expr.EmitBranchable (ec, loop, true);
+                       }
                        
                        ec.MarkLabel (ec.LoopEnd);
 
@@ -427,9 +440,13 @@ namespace Mono.CSharp {
                        //
                        // Inform whether we are infinite or not
                        //
-                       if (expr is Constant){
+                       if (expr is Constant) {
                                // expr is 'true', since the 'empty' case above handles the 'false' case
                                ec.MarkLabel (ec.LoopBegin);
+
+                               if (ec.EmitAccurateDebugInfo)
+                                       ec.Emit (OpCodes.Nop);
+
                                expr.EmitSideEffect (ec);
                                Statement.Emit (ec);
                                ec.Emit (OpCodes.Br, ec.LoopBegin);
@@ -448,8 +465,8 @@ namespace Mono.CSharp {
                                Statement.Emit (ec);
                        
                                ec.MarkLabel (ec.LoopBegin);
-                               ec.Mark (loc);
 
+                               ec.Mark (loc);
                                expr.EmitBranchable (ec, while_loop, true);
                                
                                ec.MarkLabel (ec.LoopEnd);
@@ -459,11 +476,6 @@ namespace Mono.CSharp {
                        ec.LoopEnd = old_end;
                }
 
-               public override void Emit (EmitContext ec)
-               {
-                       DoEmit (ec);
-               }
-
                protected override void CloneTo (CloneContext clonectx, Statement t)
                {
                        While target = (While) t;
@@ -592,7 +604,9 @@ namespace Mono.CSharp {
                        // If test is null, there is no test, and we are just
                        // an infinite loop
                        //
-                       if (Condition != null){
+                       if (Condition != null) {
+                               ec.Mark (Condition.Location);
+
                                //
                                // The Resolve code already catches the case for
                                // Test == Constant (false) so we know that
@@ -775,12 +789,10 @@ namespace Mono.CSharp {
 
                public sealed override bool Resolve (BlockContext ec)
                {
-                       if (!DoResolve (ec))
-                               return false;
-
+                       var res = DoResolve (ec);
                        unwind_protect = ec.CurrentBranching.AddReturnOrigin (ec.CurrentBranching.CurrentUsageVector, this);
                        ec.CurrentBranching.CurrentUsageVector.Goto ();
-                       return true;
+                       return res;
                }
        }
 
@@ -851,6 +863,8 @@ namespace Mono.CSharp {
                                        ec.Report.Error (127, loc,
                                                "`{0}': A return keyword must not be followed by any expression when method returns void",
                                                ec.GetSignatureForError ());
+
+                                       return false;
                                }
                        } else {
                                if (am.IsIterator) {
@@ -869,12 +883,20 @@ namespace Mono.CSharp {
                                                        return true;
                                                }
 
+                                               if (async_type.Kind == MemberKind.Void) {
+                                                       ec.Report.Error (127, loc,
+                                                               "`{0}': A return keyword must not be followed by any expression when method returns void",
+                                                               ec.GetSignatureForError ());
+
+                                                       return false;
+                                               }
+
                                                if (!async_type.IsGenericTask) {
                                                        if (this is ContextualReturn)
                                                                return true;
 
                                                        ec.Report.Error (1997, loc,
-                                                               "`{0}': A return keyword must not be followed by an expression when async method returns Task. Consider using Task<T>",
+                                                               "`{0}': A return keyword must not be followed by an expression when async method returns `Task'. Consider using `Task<T>' return type",
                                                                ec.GetSignatureForError ());
                                                        return false;
                                                }
@@ -882,9 +904,24 @@ namespace Mono.CSharp {
                                                //
                                                // The return type is actually Task<T> type argument
                                                //
-                                               block_return_type = async_type.TypeArguments[0];
+                                               if (expr.Type == async_type) {
+                                                       ec.Report.Error (4016, loc,
+                                                               "`{0}': The return expression type of async method must be `{1}' rather than `Task<{1}>'",
+                                                               ec.GetSignatureForError (), async_type.TypeArguments[0].GetSignatureForError ());
+                                               } else {
+                                                       block_return_type = async_type.TypeArguments[0];
+                                               }
                                        }
                                } else {
+                                       // Same error code as .NET but better error message
+                                       if (block_return_type.Kind == MemberKind.Void) {
+                                               ec.Report.Error (127, loc,
+                                                       "`{0}': A return keyword must not be followed by any expression when delegate returns void",
+                                                       am.GetSignatureForError ());
+
+                                               return false;
+                                       }
+
                                        var l = am as AnonymousMethodBody;
                                        if (l != null && l.ReturnTypeInference != null && expr != null) {
                                                l.ReturnTypeInference.AddCommonTypeBound (expr.Type);
@@ -896,7 +933,7 @@ namespace Mono.CSharp {
                        if (expr == null)
                                return false;
 
-                       if (expr.Type != block_return_type) {
+                       if (expr.Type != block_return_type && expr.Type != InternalType.ErrorType) {
                                expr = Convert.ImplicitConversionRequired (ec, expr, block_return_type, loc);
 
                                if (expr == null) {
@@ -925,20 +962,26 @@ namespace Mono.CSharp {
                                        if (async_return != null) {
                                                async_return.EmitAssign (ec);
 
-                                               ec.Emit (unwind_protect ? OpCodes.Leave : OpCodes.Br, async_body.BodyEnd);
+                                               ec.EmitEpilogue ();
                                        }
 
+                                       ec.Emit (unwind_protect ? OpCodes.Leave : OpCodes.Br, async_body.BodyEnd);
                                        return;
                                }
 
-                               if (unwind_protect)
+                               ec.EmitEpilogue ();
+
+                               if (unwind_protect || ec.EmitAccurateDebugInfo)
                                        ec.Emit (OpCodes.Stloc, ec.TemporaryReturn ());
                        }
 
-                       if (unwind_protect)
+                       if (unwind_protect) {
                                ec.Emit (OpCodes.Leave, ec.CreateReturnLabel ());
-                       else
+                       } else if (ec.EmitAccurateDebugInfo) {
+                               ec.Emit (OpCodes.Br, ec.CreateReturnLabel ());
+                       } else {
                                ec.Emit (OpCodes.Ret);
+                       }
                }
 
                void Error_ReturnFromIterator (ResolveContext rc)
@@ -1182,9 +1225,9 @@ namespace Mono.CSharp {
                                res = c;
                        } else {
                                TypeSpec type = ec.Switch.SwitchType;
-                               res = c.TryReduce (ec, type, c.Location);
+                               res = c.TryReduce (ec, type);
                                if (res == null) {
-                                       c.Error_ValueCannotBeConverted (ec, loc, type, true);
+                                       c.Error_ValueCannotBeConverted (ec, type, true);
                                        return false;
                                }
 
@@ -1405,6 +1448,7 @@ namespace Mono.CSharp {
                protected FullNamedExpression type_expr;
                protected LocalVariable li;
                protected List<Declarator> declarators;
+               TypeSpec type;
 
                public BlockVariableDeclaration (FullNamedExpression type, LocalVariable li)
                {
@@ -1457,7 +1501,7 @@ namespace Mono.CSharp {
                        declarators.Add (decl);
                }
 
-               void CreateEvaluatorVariable (BlockContext bc, LocalVariable li)
+               static void CreateEvaluatorVariable (BlockContext bc, LocalVariable li)
                {
                        if (bc.Report.Errors != 0)
                                return;
@@ -1481,8 +1525,7 @@ namespace Mono.CSharp {
 
                public bool Resolve (BlockContext bc, bool resolveDeclaratorInitializers)
                {
-                       if (li.Type == null) {
-                               TypeSpec type = null;
+                       if (type == null && !li.IsCompilerGenerated) {
                                var vexpr = type_expr as VarExpr;
 
                                //
@@ -1582,9 +1625,6 @@ namespace Mono.CSharp {
 
                protected override void DoEmit (EmitContext ec)
                {
-                       if (li.IsConstant)
-                               return;
-
                        li.CreateBuilder (ec);
 
                        if (Initializer != null)
@@ -1593,8 +1633,10 @@ namespace Mono.CSharp {
                        if (declarators != null) {
                                foreach (var d in declarators) {
                                        d.Variable.CreateBuilder (ec);
-                                       if (d.Initializer != null)
+                                       if (d.Initializer != null) {
+                                               ec.Mark (d.Variable.Location);
                                                ((ExpressionStatement) d.Initializer).EmitStatement (ec);
+                                       }
                                }
                        }
                }
@@ -1629,6 +1671,11 @@ namespace Mono.CSharp {
                {
                }
 
+               public override void Emit (EmitContext ec)
+               {
+                       // Nothing to emit, not even sequence point
+               }
+
                protected override Expression ResolveInitializer (BlockContext bc, LocalVariable li, Expression initializer)
                {
                        initializer = initializer.Resolve (bc);
@@ -1646,7 +1693,7 @@ namespace Mono.CSharp {
                                if (TypeSpec.IsReferenceType (li.Type))
                                        initializer.Error_ConstantCanBeInitializedWithNullOnly (bc, li.Type, initializer.Location, li.Name);
                                else
-                                       initializer.Error_ValueCannotBeConverted (bc, initializer.Location, li.Type, false);
+                                       initializer.Error_ValueCannotBeConverted (bc, li.Type, false);
 
                                return null;
                        }
@@ -1757,6 +1804,12 @@ namespace Mono.CSharp {
                        }
                }
 
+               public bool IsCompilerGenerated {
+                       get {
+                               return (flags & Flags.CompilerGenerated) != 0;
+                       }
+               }
+
                public bool IsConstant {
                        get {
                                return (flags & Flags.Constant) != 0;
@@ -1848,7 +1901,7 @@ namespace Mono.CSharp {
                        // All fixed variabled are pinned, a slot has to be alocated
                        //
                        builder = ec.DeclareLocal (Type, IsFixed);
-                       if (SymbolWriter.HasSymbolWriter)
+                       if (!ec.HasSet (BuilderContext.Options.OmitDebugInfo) && (flags & Flags.CompilerGenerated) == 0)
                                ec.DefineLocalVariable (name, builder);
                }
 
@@ -2048,8 +2101,13 @@ namespace Mono.CSharp {
 
                #region Properties
 
-               public bool HasRet {
-                       get { return (flags & Flags.HasRet) != 0; }
+               public bool HasUnreachableClosingBrace {
+                       get {
+                               return (flags & Flags.HasRet) != 0;
+                       }
+                       set {
+                               flags = value ? flags | Flags.HasRet : flags & ~Flags.HasRet;
+                       }
                }
 
                public Block Original {
@@ -2283,7 +2341,8 @@ namespace Mono.CSharp {
                        if (warn)
                                ec.Report.Warning (162, 2, loc, "Unreachable code detected");
 
-                       ec.StartFlowBranching (FlowBranching.BranchingType.Block, loc);
+                       var fb = ec.StartFlowBranching (FlowBranching.BranchingType.Block, loc);
+                       fb.CurrentUsageVector.IsUnreachable = true;
                        bool ok = Resolve (ec);
                        ec.KillFlowBranching ();
 
@@ -2303,9 +2362,6 @@ namespace Mono.CSharp {
                                EmitScopeInitializers (ec);
 
                        DoEmit (ec);
-
-                       if (SymbolWriter.HasSymbolWriter)
-                               EmitSymbolInfo (ec);
                }
 
                protected void EmitScopeInitializers (EmitContext ec)
@@ -2314,10 +2370,6 @@ namespace Mono.CSharp {
                                s.Emit (ec);
                }
 
-               protected virtual void EmitSymbolInfo (EmitContext ec)
-               {
-               }
-
 #if DEBUG
                public override string ToString ()
                {
@@ -2383,14 +2435,22 @@ namespace Mono.CSharp {
                }
 
                public bool HasCapturedThis {
-                       set { flags = value ? flags | Flags.HasCapturedThis : flags & ~Flags.HasCapturedThis; }
+                       set {
+                               flags = value ? flags | Flags.HasCapturedThis : flags & ~Flags.HasCapturedThis;
+                       }
                        get {
                                return (flags & Flags.HasCapturedThis) != 0;
                        }
                }
 
+               //
+               // Used to indicate that the block has reference to parent
+               // block and cannot be made static when defining anonymous method
+               //
                public bool HasCapturedVariable {
-                       set { flags = value ? flags | Flags.HasCapturedVariable : flags & ~Flags.HasCapturedVariable; }
+                       set {
+                               flags = value ? flags | Flags.HasCapturedVariable : flags & ~Flags.HasCapturedVariable;
+                       }
                        get {
                                return (flags & Flags.HasCapturedVariable) != 0;
                        }
@@ -2416,21 +2476,13 @@ namespace Mono.CSharp {
                        if (ec.CurrentAnonymousMethod is StateMachineInitializer && ParametersBlock.Original == ec.CurrentAnonymousMethod.Block.Original)
                                return ec.CurrentAnonymousMethod.Storey;
 
-                       //
-                       // When referencing a variable in parent iterator/async storey
-                       // from nested anonymous method
-                       //
-                       if (ParametersBlock.am_storey is StateMachine) {
-                               return ParametersBlock.am_storey;
-                       }
-
                        if (am_storey == null) {
                                MemberBase mc = ec.MemberContext as MemberBase;
 
                                //
                                // Creates anonymous method storey for this block
                                //
-                               am_storey = new AnonymousMethodStorey (this, ec.CurrentMemberDefinition.Parent.PartialContainer, mc, ec.CurrentTypeParameters, "AnonStorey");
+                               am_storey = new AnonymousMethodStorey (this, ec.CurrentMemberDefinition.Parent.PartialContainer, mc, ec.CurrentTypeParameters, "AnonStorey", MemberKind.Class);
                        }
 
                        return am_storey;
@@ -2439,71 +2491,136 @@ namespace Mono.CSharp {
                public override void Emit (EmitContext ec)
                {
                        if (am_storey != null) {
-                               DefineAnonymousStorey (ec);
+                               DefineStoreyContainer (ec, am_storey);
                                am_storey.EmitStoreyInstantiation (ec, this);
                        }
 
-                       bool emit_debug_info = SymbolWriter.HasSymbolWriter && Parent != null && !(am_storey is IteratorStorey);
-                       if (emit_debug_info)
+                       if (scope_initializers != null)
+                               EmitScopeInitializers (ec);
+
+                       if (ec.EmitAccurateDebugInfo && !IsCompilerGenerated && ec.Mark (StartLocation)) {
+                               ec.Emit (OpCodes.Nop);
+                       }
+
+                       if (Parent != null)
                                ec.BeginScope ();
 
-                       base.Emit (ec);
+                       DoEmit (ec);
 
-                       if (emit_debug_info)
+                       if (Parent != null)
                                ec.EndScope ();
+
+                       if (ec.EmitAccurateDebugInfo && !HasUnreachableClosingBrace && !IsCompilerGenerated && ec.Mark (EndLocation)) {
+                               ec.Emit (OpCodes.Nop);
+                       }
                }
 
-               void DefineAnonymousStorey (EmitContext ec)
+               protected void DefineStoreyContainer (EmitContext ec, AnonymousMethodStorey storey)
                {
+                       if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.Storey != null) {
+                               storey.SetNestedStoryParent (ec.CurrentAnonymousMethod.Storey);
+                               storey.Mutator = ec.CurrentAnonymousMethod.Storey.Mutator;
+                       }
+
                        //
                        // Creates anonymous method storey
                        //
-                       if (ec.CurrentAnonymousMethod != null && ec.CurrentAnonymousMethod.Storey != null) {
+                       storey.CreateContainer ();
+                       storey.DefineContainer ();
+
+                       if (Original.Explicit.HasCapturedThis && Original.ParametersBlock.TopBlock.ThisReferencesFromChildrenBlock != null) {
+
                                //
-                               // Creates parent storey reference when hoisted this is accessible
+                               // Only first storey in path will hold this reference. All children blocks will
+                               // reference it indirectly using $ref field
                                //
-                               if (am_storey.OriginalSourceBlock.Explicit.HasCapturedThis) {
-                                       ExplicitBlock parent = am_storey.OriginalSourceBlock.Explicit.Parent.Explicit;
+                               for (Block b = Original.Explicit.Parent; b != null; b = b.Parent) {
+                                       var s = b.Explicit.AnonymousMethodStorey;
+                                       if (s != null) {
+                                               storey.HoistedThis = s.HoistedThis;
+                                               break;
+                                       }
+                               }
 
-                                       //
-                                       // Hoisted this exists in top-level parent storey only
-                                       //
-                                       while (parent.am_storey == null || parent.am_storey.Parent is AnonymousMethodStorey)
-                                               parent = parent.Parent.Explicit;
+                               //
+                               // 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) {
+                                               //
+                                               // ThisReferencesFromChildrenBlock holds all reference even if they
+                                               // are not on this path. It saves some memory otherwise it'd have to
+                                               // be in every explicit block. We run this check to see if the reference
+                                               // is valid for this storey
+                                               //
+                                               Block block_on_path = ref_block;
+                                               for (; block_on_path != null && block_on_path != Original; block_on_path = block_on_path.Parent);
 
-                                       am_storey.AddParentStoreyReference (ec, parent.am_storey);
-                               }
+                                               if (block_on_path == null)
+                                                       continue;
 
-                               am_storey.SetNestedStoryParent (ec.CurrentAnonymousMethod.Storey);
+                                               if (storey.HoistedThis == null)
+                                                       storey.AddCapturedThisField (ec);
 
-                               // TODO MemberCache: Review
-                               am_storey.Mutator = ec.CurrentAnonymousMethod.Storey.Mutator;
-                       }
+                                               for (ExplicitBlock b = ref_block; b.AnonymousMethodStorey != storey; b = b.Parent.Explicit) {
+                                                       if (b.AnonymousMethodStorey != null) {
+                                                               b.AnonymousMethodStorey.AddParentStoreyReference (ec, storey);
+                                                               b.AnonymousMethodStorey.HoistedThis = storey.HoistedThis;
 
-                       am_storey.CreateContainer ();
-                       am_storey.DefineContainer ();
+                                                               //
+                                                               // Stop propagation inside same top block
+                                                               //
+                                                               if (b.ParametersBlock == ParametersBlock.Original)
+                                                                       break;
 
-                       var ref_blocks = am_storey.ReferencesFromChildrenBlock;
+                                                               b = b.ParametersBlock;
+                                                       }
+
+                                                       var pb = b as ParametersBlock;
+                                                       if (pb != null && pb.StateMachine != null) {
+                                                               if (pb.StateMachine == storey)
+                                                                       break;
+
+                                                               pb.StateMachine.AddParentStoreyReference (ec, storey);
+                                                       }
+
+                                                       b.HasCapturedVariable = true;
+                                               }
+                                       }
+                               }
+                       }
+
+                       var ref_blocks = storey.ReferencesFromChildrenBlock;
                        if (ref_blocks != null) {
                                foreach (ExplicitBlock ref_block in ref_blocks) {
-                                       for (ExplicitBlock b = ref_block.Explicit; b.am_storey != am_storey; b = b.Parent.Explicit) {
-                                               if (b.am_storey != null) {
-                                                       b.am_storey.AddParentStoreyReference (ec, am_storey);
+                                       for (ExplicitBlock b = ref_block; b.AnonymousMethodStorey != storey; b = b.Parent.Explicit) {
+                                               if (b.AnonymousMethodStorey != null) {
+                                                       b.AnonymousMethodStorey.AddParentStoreyReference (ec, storey);
 
+                                                       //
                                                        // Stop propagation inside same top block
-                                                       if (b.ParametersBlock.Original == ParametersBlock.Original)
+                                                       //
+                                                       if (b.ParametersBlock == ParametersBlock.Original)
                                                                break;
 
                                                        b = b.ParametersBlock;
                                                }
 
+                                               var pb = b as ParametersBlock;
+                                               if (pb != null && pb.StateMachine != null) {
+                                                       if (pb.StateMachine == storey)
+                                                               break;
+
+                                                       pb.StateMachine.AddParentStoreyReference (ec, storey);
+                                               }
+
                                                b.HasCapturedVariable = true;
                                        }
                                }
                        }
 
-                       am_storey.Define ();
-                       am_storey.Parent.PartialContainer.AddCompilerGeneratedClass (am_storey);
+                       storey.Define ();
+                       storey.Parent.PartialContainer.AddCompilerGeneratedClass (storey);
                }
 
                public void RegisterAsyncAwait ()
@@ -2512,7 +2629,7 @@ namespace Mono.CSharp {
                        while ((block.flags & Flags.AwaitBlock) == 0) {
                                block.flags |= Flags.AwaitBlock;
 
-                               if (block.Parent == null)
+                               if (block is ParametersBlock)
                                        return;
 
                                block = block.Parent.Explicit;
@@ -2561,7 +2678,13 @@ namespace Mono.CSharp {
 
                        #region Properties
 
-                       public Block Block {
+                       public ParametersBlock Block {
+                               get {
+                                       return block;
+                               }
+                       }
+
+                       Block INamedBlockVariable.Block {
                                get {
                                        return block;
                                }
@@ -2664,6 +2787,7 @@ namespace Mono.CSharp {
                bool resolved;
                protected bool unreachable;
                protected ToplevelBlock top_block;
+               protected StateMachine state_machine;
 
                public ParametersBlock (Block parent, ParametersCompiled parameters, Location start)
                        : base (parent, 0, start, start)
@@ -2703,6 +2827,7 @@ namespace Mono.CSharp {
                        this.resolved = true;
                        this.unreachable = source.unreachable;
                        this.am_storey = source.am_storey;
+                       this.state_machine = source.state_machine;
 
                        ParametersBlock = this;
 
@@ -2710,7 +2835,7 @@ namespace Mono.CSharp {
                        // Overwrite original for comparison purposes when linking cross references
                        // between anonymous methods
                        //
-                       Original = source;
+                       Original = source.Original;
                }
 
                #region Properties
@@ -2742,6 +2867,12 @@ namespace Mono.CSharp {
                        }
                }
 
+               public StateMachine StateMachine {
+                       get {
+                               return state_machine;
+                       }
+               }
+
                public ToplevelBlock TopBlock {
                        get {
                                return top_block;
@@ -2797,6 +2928,26 @@ namespace Mono.CSharp {
                        return base.CreateExpressionTree (ec);
                }
 
+               public override void Emit (EmitContext ec)
+               {
+                       if (state_machine != null && state_machine.OriginalSourceBlock != this) {
+                               DefineStoreyContainer (ec, state_machine);
+                               state_machine.EmitStoreyInstantiation (ec, this);
+                       }
+
+                       base.Emit (ec);
+               }
+
+               public void EmitEmbedded (EmitContext ec)
+               {
+                       if (state_machine != null && state_machine.OriginalSourceBlock != this) {
+                               DefineStoreyContainer (ec, state_machine);
+                               state_machine.EmitStoreyInstantiation (ec, this);
+                       }
+
+                       base.Emit (ec);
+               }
+
                public ParameterInfo GetParameterInfo (Parameter p)
                {
                        for (int i = 0; i < parameters.Count; ++i) {
@@ -2807,7 +2958,7 @@ namespace Mono.CSharp {
                        throw new ArgumentException ("Invalid parameter");
                }
 
-               public Expression GetParameterReference (int index, Location loc)
+               public ParameterReference GetParameterReference (int index, Location loc)
                {
                        return new ParameterReference (parameter_info[index], loc);
                }
@@ -2858,7 +3009,7 @@ namespace Mono.CSharp {
                                        unreachable = top_level.End ();
                                }
                        } catch (Exception e) {
-                               if (e is CompletionResult || rc.Report.IsDisabled)
+                               if (e is CompletionResult || rc.Report.IsDisabled || e is FatalException)
                                        throw;
 
                                if (rc.CurrentBlock != null) {
@@ -2910,7 +3061,7 @@ namespace Mono.CSharp {
                        for (int i = 0; i < orig_count; ++i) {
                                Parameter.Modifier mod = parameters.FixedParameters[i].ModFlags;
 
-                               if ((mod & Parameter.Modifier.OUT) != Parameter.Modifier.OUT)
+                               if ((mod & Parameter.Modifier.OUT) == 0)
                                        continue;
 
                                VariableInfo vi = new VariableInfo (parameters, i, ec.FlowOffset);
@@ -2919,37 +3070,71 @@ namespace Mono.CSharp {
                        }
                }
 
-               public void WrapIntoIterator (IMethodData method, TypeDefinition host, TypeSpec iterator_type, bool is_enumerable)
+               public ToplevelBlock ConvertToIterator (IMethodData method, TypeDefinition host, TypeSpec iterator_type, bool is_enumerable)
                {
-                       ParametersBlock pb = new ParametersBlock (this, ParametersCompiled.EmptyReadOnlyParameters, StartLocation);
-                       pb.EndLocation = EndLocation;
-                       pb.statements = statements;
-                       pb.Original = this;
+                       var iterator = new Iterator (this, method, host, iterator_type, is_enumerable);
+                       var stateMachine = new IteratorStorey (iterator);
 
-                       var iterator = new Iterator (pb, method, host, iterator_type, is_enumerable);
-                       am_storey = new IteratorStorey (iterator);
+                       state_machine = stateMachine;
+                       iterator.SetStateMachine (stateMachine);
 
-                       statements = new List<Statement> (1);
-                       AddStatement (new Return (iterator, iterator.Location));
-                       flags &= ~Flags.YieldBlock;
+                       var tlb = new ToplevelBlock (host.Compiler, Parameters, Location.Null);
+                       tlb.Original = this;
+                       tlb.IsCompilerGenerated = true;
+                       tlb.state_machine = stateMachine;
+                       tlb.AddStatement (new Return (iterator, iterator.Location));
+                       return tlb;
                }
 
-               public void WrapIntoAsyncTask (IMemberContext context, TypeDefinition host, TypeSpec returnType)
+               public ParametersBlock ConvertToAsyncTask (IMemberContext context, TypeDefinition host, ParametersCompiled parameters, TypeSpec returnType, Location loc)
                {
-                       ParametersBlock pb = new ParametersBlock (this, ParametersCompiled.EmptyReadOnlyParameters, StartLocation);
-                       pb.EndLocation = EndLocation;
-                       pb.statements = statements;
-                       pb.Original = this;
+                       for (int i = 0; i < parameters.Count; i++) {
+                               Parameter p = parameters[i];
+                               Parameter.Modifier mod = p.ModFlags;
+                               if ((mod & Parameter.Modifier.RefOutMask) != 0) {
+                                       host.Compiler.Report.Error (1988, p.Location,
+                                               "Async methods cannot have ref or out parameters");
+                                       return this;
+                               }
+
+                               if (p is ArglistParameter) {
+                                       host.Compiler.Report.Error (4006, p.Location,
+                                               "__arglist is not allowed in parameter list of async methods");
+                                       return this;
+                               }
+
+                               if (parameters.Types[i].IsPointer) {
+                                       host.Compiler.Report.Error (4005, p.Location,
+                                               "Async methods cannot have unsafe parameters");
+                                       return this;
+                               }
+                       }
+
+                       if (!HasAwait) {
+                               host.Compiler.Report.Warning (1998, 1, loc,
+                                       "Async block lacks `await' operator and will run synchronously");
+                       }
 
                        var block_type = host.Module.Compiler.BuiltinTypes.Void;
-                       var initializer = new AsyncInitializer (pb, host, block_type);
+                       var initializer = new AsyncInitializer (this, host, block_type);
                        initializer.Type = block_type;
 
-                       am_storey = new AsyncTaskStorey (context, initializer, returnType);
+                       var stateMachine = new AsyncTaskStorey (this, context, initializer, returnType);
 
-                       statements = new List<Statement> (1);
-                       AddStatement (new StatementExpression (initializer));
-                       flags &= ~Flags.AwaitBlock;
+                       state_machine = stateMachine;
+                       initializer.SetStateMachine (stateMachine);
+
+                       var b = this is ToplevelBlock ?
+                               new ToplevelBlock (host.Compiler, Parameters, Location.Null) :
+                               new ParametersBlock (Parent, parameters, Location.Null) {
+                                       IsAsync = true,
+                               };
+
+                       b.Original = this;
+                       b.IsCompilerGenerated = true;
+                       b.state_machine = stateMachine;
+                       b.AddStatement (new StatementExpression (initializer));
+                       return b;
                }
        }
 
@@ -2963,11 +3148,7 @@ namespace Mono.CSharp {
                Dictionary<string, object> names;
                Dictionary<string, object> labels;
 
-               public HoistedVariable HoistedThisVariable;
-
-               public Report Report {
-                       get { return compiler.Report; }
-               }
+               List<ExplicitBlock> this_references;
 
                public ToplevelBlock (CompilerContext ctx, Location loc)
                        : this (ctx, ParametersCompiled.EmptyReadOnlyParameters, loc)
@@ -2979,6 +3160,7 @@ namespace Mono.CSharp {
                {
                        this.compiler = ctx;
                        top_block = this;
+                       flags |= Flags.HasRet;
 
                        ProcessParameters ();
                }
@@ -2994,6 +3176,7 @@ namespace Mono.CSharp {
                {
                        this.compiler = source.TopBlock.compiler;
                        top_block = this;
+                       flags |= Flags.HasRet;
                }
 
                public bool IsIterator {
@@ -3002,6 +3185,31 @@ namespace Mono.CSharp {
                        }
                }
 
+               public Report Report {
+                       get {
+                               return compiler.Report;
+                       }
+               }
+
+               //
+               // Used by anonymous blocks to track references of `this' variable
+               //
+               public List<ExplicitBlock> ThisReferencesFromChildrenBlock {
+                       get {
+                               return this_references;
+                       }
+               }
+
+               //
+               // Returns the "this" instance variable of this block.
+               // See AddThisVariable() for more information.
+               //
+               public LocalVariable ThisVariable {
+                       get {
+                               return this_variable;
+                       }
+               }
+
                public void AddLocalName (string name, INamedBlockVariable li, bool ignoreChildrenBlocks)
                {
                        if (names == null)
@@ -3028,18 +3236,18 @@ namespace Mono.CSharp {
                        //
                        for (int i = 0; i < existing_list.Count; ++i) {
                                existing = existing_list[i];
-                               Block b = existing.Block;
+                               Block b = existing.Block.Explicit;
 
                                // Collision at same level
-                               if (li.Block == b) {
+                               if (li.Block.Explicit == b) {
                                        li.Block.Error_AlreadyDeclared (name, li);
                                        break;
                                }
 
                                // Collision with parent
-                               b = li.Block;
-                               while ((b = b.Parent) != null) {
-                                       if (existing.Block == b) {
+                               Block parent = li.Block.Explicit;
+                               while ((parent = parent.Parent) != null) {
+                                       if (parent == b) {
                                                li.Block.Error_AlreadyDeclared (name, li, "parent or current");
                                                i = existing_list.Count;
                                                break;
@@ -3048,9 +3256,8 @@ namespace Mono.CSharp {
 
                                if (!ignoreChildrenBlocks) {
                                        // Collision with children
-                                       b = existing.Block;
                                        while ((b = b.Parent) != null) {
-                                               if (li.Block == b) {
+                                               if (li.Block.Explicit == b) {
                                                        li.Block.Error_AlreadyDeclared (name, li, "child");
                                                        i = existing_list.Count;
                                                        break;
@@ -3123,6 +3330,20 @@ namespace Mono.CSharp {
                        existing_list.Add (label);
                }
 
+               public void AddThisReferenceFromChildrenBlock (ExplicitBlock block)
+               {
+                       if (this_references == null)
+                               this_references = new List<ExplicitBlock> ();
+
+                       if (!this_references.Contains (block))
+                               this_references.Add (block);
+               }
+
+               public void RemoveThisReferenceFromChildrenBlock (ExplicitBlock block)
+               {
+                       this_references.Remove (block);
+               }
+
                //
                // Creates an arguments set from all parameters, useful for method proxy calls
                //
@@ -3233,14 +3454,6 @@ namespace Mono.CSharp {
                        return null;
                }
 
-               // <summary>
-               //   Returns the "this" instance variable of this block.
-               //   See AddThisVariable() for more information.
-               // </summary>
-               public LocalVariable ThisVariable {
-                       get { return this_variable; }
-               }
-
                // <summary>
                //   This is used by non-static `struct' constructors which do not have an
                //   initializer - in this case, the constructor must initialize all of the
@@ -3277,34 +3490,31 @@ namespace Mono.CSharp {
                                }
                        } else {
                                base.Emit (ec);
-                               ec.Mark (EndLocation);
                        }
 
-                       if (ec.HasReturnLabel)
-                               ec.MarkLabel (ec.ReturnLabel);
+                       //
+                       // If `HasReturnLabel' is set, then we already emitted a
+                       // jump to the end of the method, so we must emit a `ret'
+                       // there.
+                       //
+                       // Unfortunately, System.Reflection.Emit automatically emits
+                       // a leave to the end of a finally block.  This is a problem
+                       // if no code is following the try/finally block since we may
+                       // jump to a point after the end of the method.
+                       // As a workaround, we're always creating a return label in
+                       // this case.
+                       //
+                       if (ec.HasReturnLabel || !unreachable) {
+                               if (ec.HasReturnLabel)
+                                       ec.MarkLabel (ec.ReturnLabel);
 
-                       if (ec.return_value != null) {
-                               ec.Emit (OpCodes.Ldloc, ec.return_value);
-                               ec.Emit (OpCodes.Ret);
-                       } else {
-                               //
-                               // If `HasReturnLabel' is set, then we already emitted a
-                               // jump to the end of the method, so we must emit a `ret'
-                               // there.
-                               //
-                               // Unfortunately, System.Reflection.Emit automatically emits
-                               // a leave to the end of a finally block.  This is a problem
-                               // if no code is following the try/finally block since we may
-                               // jump to a point after the end of the method.
-                               // As a workaround, we're always creating a return label in
-                               // this case.
-                               //
+                               if (ec.EmitAccurateDebugInfo && !IsCompilerGenerated)
+                                       ec.Mark (EndLocation);
 
-                               if (ec.HasReturnLabel || !unreachable) {
-                                       if (ec.ReturnType.Kind != MemberKind.Void)
-                                               ec.Emit (OpCodes.Ldloc, ec.TemporaryReturn ());
-                                       ec.Emit (OpCodes.Ret);
-                               }
+                               if (ec.ReturnType.Kind != MemberKind.Void)
+                                       ec.Emit (OpCodes.Ldloc, ec.TemporaryReturn ());
+
+                               ec.Emit (OpCodes.Ret);
                        }
 
 #if PRODUCTION
@@ -3317,15 +3527,6 @@ namespace Mono.CSharp {
                        }
 #endif
                }
-
-               protected override void EmitSymbolInfo (EmitContext ec)
-               {
-                       AnonymousExpression ae = ec.CurrentAnonymousMethod;
-                       if ((ae != null) && (ae.Storey != null))
-                               SymbolWriter.DefineScopeVariable (ae.Storey.ID);
-
-                       base.EmitSymbolInfo (ec);
-               }
        }
        
        public class SwitchLabel {
@@ -4050,16 +4251,19 @@ namespace Mono.CSharp {
 
                                Expression cond = null;
                                for (int ci = 0; ci < s.Labels.Count; ++ci) {
-                                       var e = new Binary (Binary.Operator.Equality, value, s.Labels[ci].Converted, loc);
+                                       var e = new Binary (Binary.Operator.Equality, value, s.Labels[ci].Converted);
 
                                        if (ci > 0) {
-                                               cond = new Binary (Binary.Operator.LogicalOr, cond, e, loc);
+                                               cond = new Binary (Binary.Operator.LogicalOr, cond, e);
                                        } else {
                                                cond = e;
                                        }
                                }
 
-                               simple_stmt = new If (cond, s.Block, simple_stmt, loc);
+                               //
+                               // Compiler generated, hide from symbol file
+                               //
+                               simple_stmt = new If (cond, s.Block, simple_stmt, Location.Null);
                        }
 
                        // It's null for empty switch
@@ -4088,7 +4292,7 @@ namespace Mono.CSharp {
                        var ctype = ec.CurrentMemberDefinition.Parent.PartialContainer;
                        Field field = new Field (ctype, string_dictionary_type,
                                Modifiers.STATIC | Modifiers.PRIVATE | Modifiers.COMPILER_GENERATED,
-                               new MemberName (CompilerGeneratedClass.MakeName (null, "f", "switch$map", ec.Module.CounterSwitchTypes++), loc), null);
+                               new MemberName (CompilerGeneratedContainer.MakeName (null, "f", "switch$map", ec.Module.CounterSwitchTypes++), loc), null);
                        if (!field.Define ())
                                return;
                        ctype.AddField (field);
@@ -4147,7 +4351,9 @@ namespace Mono.CSharp {
                        // Check if string dictionary is initialized and initialize
                        //
                        switch_cache_field.EmitBranchable (ec, l_initialized, true);
-                       string_dictionary.EmitStatement (ec);
+                       using (ec.With (BuilderContext.Options.OmitDebugInfo, true)) {
+                               string_dictionary.EmitStatement (ec);
+                       }
                        ec.MarkLabel (l_initialized);
 
                        LocalTemporary string_switch_variable = new LocalTemporary (ec.BuiltinTypes.Int);
@@ -4191,6 +4397,9 @@ namespace Mono.CSharp {
 
                protected override void DoEmit (EmitContext ec)
                {
+                       // Workaround broken flow-analysis
+                       block.HasUnreachableClosingBrace = true;
+
                        //
                        // Needed to emit anonymous storey initialization
                        // Otherwise it does not contain any statements for now
@@ -4286,6 +4495,7 @@ namespace Mono.CSharp {
                protected Statement stmt;
                Label dispose_try_block;
                bool prepared_for_dispose, emitted_dispose;
+               Method finally_host;
 
                protected TryFinallyBlock (Statement stmt, Location loc)
                        : base (loc)
@@ -4304,7 +4514,7 @@ namespace Mono.CSharp {
                #endregion
 
                protected abstract void EmitTryBody (EmitContext ec);
-               protected abstract void EmitFinallyBody (EmitContext ec);
+               public abstract void EmitFinallyBody (EmitContext ec);
 
                public override Label PrepareForDispose (EmitContext ec, Label end)
                {
@@ -4332,7 +4542,20 @@ namespace Mono.CSharp {
                        }
 
                        ec.MarkLabel (start_finally);
-                       EmitFinallyBody (ec);
+
+                       if (finally_host != null) {
+                               finally_host.Define ();
+                               finally_host.Emit ();
+
+                               // Now it's safe to add, to close it properly and emit sequence points
+                               finally_host.Parent.AddMember (finally_host);
+
+                               var ce = new CallEmitter ();
+                               ce.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
+                               ce.EmitPredefined (ec, finally_host.Spec, new Arguments (0));
+                       } else {
+                               EmitFinallyBody (ec);
+                       }
 
                        ec.EndExceptionBlock ();
                }
@@ -4376,12 +4599,10 @@ namespace Mono.CSharp {
                                bool emit_dispatcher = j < labels.Length;
 
                                if (emit_dispatcher) {
-                                       //SymbolWriter.StartIteratorDispatcher (ec.ig);
                                        ec.Emit (OpCodes.Ldloc, pc);
                                        ec.EmitInt (first_resume_pc);
                                        ec.Emit (OpCodes.Sub);
                                        ec.Emit (OpCodes.Switch, labels);
-                                       //SymbolWriter.EndIteratorDispatcher (ec.ig);
                                }
 
                                foreach (ResumableStatement s in resume_points)
@@ -4392,10 +4613,34 @@ namespace Mono.CSharp {
 
                        ec.BeginFinallyBlock ();
 
-                       EmitFinallyBody (ec);
+                       if (finally_host != null) {
+                               var ce = new CallEmitter ();
+                               ce.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
+                               ce.EmitPredefined (ec, finally_host.Spec, new Arguments (0));
+                       } else {
+                               EmitFinallyBody (ec);
+                       }
 
                        ec.EndExceptionBlock ();
                }
+
+               public override bool Resolve (BlockContext bc)
+               {
+                       //
+                       // Finally block inside iterator is called from MoveNext and
+                       // Dispose methods that means we need to lift the block into
+                       // newly created host method to emit the body only once. The
+                       // original block then simply calls the newly generated method.
+                       //
+                       if (bc.CurrentIterator != null && !bc.IsInProbingMode) {
+                               var b = stmt as Block;
+                               if (b != null && b.Explicit.HasYield) {
+                                       finally_host = bc.CurrentIterator.CreateFinallyHost (this);
+                               }
+                       }
+
+                       return base.Resolve (bc);
+               }
        }
 
        //
@@ -4519,21 +4764,9 @@ namespace Mono.CSharp {
                                locked = false;
                        }
 
-                       using (ec.Set (ResolveContext.Options.LockScope)) {
-                               ec.StartFlowBranching (this);
-                               Statement.Resolve (ec);
-                               ec.EndFlowBranching ();
-                       }
-
-                       if (lv != null) {
-                               lv.IsLockedByStatement = locked;
-                       }
-
-                       base.Resolve (ec);
-
                        //
                        // Have to keep original lock value around to unlock same location
-                       // in the case the original has changed or is null
+                       // in the case of original value has changed or is null
                        //
                        expr_copy = TemporaryVariableReference.Create (ec.BuiltinTypes.Object, ec.CurrentBlock, loc);
                        expr_copy.Resolve (ec);
@@ -4546,6 +4779,18 @@ namespace Mono.CSharp {
                                lock_taken.Resolve (ec);
                        }
 
+                       using (ec.Set (ResolveContext.Options.LockScope)) {
+                               ec.StartFlowBranching (this);
+                               Statement.Resolve (ec);
+                               ec.EndFlowBranching ();
+                       }
+
+                       if (lv != null) {
+                               lv.IsLockedByStatement = locked;
+                       }
+
+                       base.Resolve (ec);
+
                        return true;
                }
                
@@ -4584,7 +4829,7 @@ namespace Mono.CSharp {
                        Statement.Emit (ec);
                }
 
-               protected override void EmitFinallyBody (EmitContext ec)
+               public override void EmitFinallyBody (EmitContext ec)
                {
                        //
                        // if (lock_taken) Monitor.Exit (expr_copy)
@@ -4899,8 +5144,8 @@ namespace Mono.CSharp {
                                        // fixed (T* e_ptr = (e == null || e.Length == 0) ? null : converted [0])
                                        //
                                        converted = new Conditional (new BooleanExpression (new Binary (Binary.Operator.LogicalOr,
-                                               new Binary (Binary.Operator.Equality, initializer, new NullLiteral (loc), loc),
-                                               new Binary (Binary.Operator.Equality, new MemberAccess (initializer, "Length"), new IntConstant (bc.BuiltinTypes, 0, loc), loc), loc)),
+                                               new Binary (Binary.Operator.Equality, initializer, new NullLiteral (loc)),
+                                               new Binary (Binary.Operator.Equality, new MemberAccess (initializer, "Length"), new IntConstant (bc.BuiltinTypes, 0, loc)))),
                                                        new NullLiteral (loc),
                                                        converted, loc);
 
@@ -5097,17 +5342,13 @@ namespace Mono.CSharp {
                                //
                                if (li.HoistedVariant != null) {
                                        LocalTemporary lt = new LocalTemporary (li.Type);
-                                       SymbolWriter.OpenCompilerGeneratedBlock (ec);
                                        lt.Store (ec);
-                                       SymbolWriter.CloseCompilerGeneratedBlock (ec);
 
                                        // switch to assigning from the temporary variable and not from top of the stack
                                        assign.UpdateSource (lt);
                                }
                        } else {
-                               SymbolWriter.OpenCompilerGeneratedBlock (ec);
                                ec.Emit (OpCodes.Pop);
-                               SymbolWriter.CloseCompilerGeneratedBlock (ec);
                        }
 
                        Block.Emit (ec);
@@ -5132,8 +5373,11 @@ namespace Mono.CSharp {
                                                if (li.Type.IsGenericParameter)
                                                        source = new UnboxCast (source, li.Type);
 
-                                               assign = new CompilerAssign (new LocalVariableReference (li, loc), source, loc);
-                                               Block.AddScopeStatement (new StatementExpression (assign));
+                                               //
+                                               // Uses Location.Null to hide from symbol file
+                                               //
+                                               assign = new CompilerAssign (new LocalVariableReference (li, Location.Null), source, Location.Null);
+                                               Block.AddScopeStatement (new StatementExpression (assign, Location.Null));
                                        }
                                }
 
@@ -5179,6 +5423,7 @@ namespace Mono.CSharp {
 
                        if (ok)
                                ec.CurrentBranching.CreateSibling (fini, FlowBranching.SiblingType.Finally);
+
                        using (ec.With (ResolveContext.Options.FinallyScope, true)) {
                                if (!fini.Resolve (ec))
                                        ok = false;
@@ -5196,7 +5441,7 @@ namespace Mono.CSharp {
                        stmt.Emit (ec);
                }
 
-               protected override void EmitFinallyBody (EmitContext ec)
+               public override void EmitFinallyBody (EmitContext ec)
                {
                        fini.Emit (ec);
                }
@@ -5451,11 +5696,14 @@ namespace Mono.CSharp {
                                        new Cast (new TypeExpression (idt, loc), lvr, loc).Resolve (bc) :
                                        lvr;
 
-                               Statement dispose = new StatementExpression (new Invocation (dispose_mg, null));
+                               //
+                               // Hide it from symbol file via null location
+                               //
+                               Statement dispose = new StatementExpression (new Invocation (dispose_mg, null), Location.Null);
 
                                // Add conditional call when disposing possible null variable
                                if (!type.IsStruct || type.IsNullableType)
-                                       dispose = new If (new Binary (Binary.Operator.Inequality, lvr, new NullLiteral (loc), loc), dispose, loc);
+                                       dispose = new If (new Binary (Binary.Operator.Inequality, lvr, new NullLiteral (loc)), dispose, dispose.loc);
 
                                return dispose;
                        }
@@ -5469,7 +5717,7 @@ namespace Mono.CSharp {
                        {
                                for (int i = declarators.Count - 1; i >= 0; --i) {
                                        var d = declarators [i];
-                                       var vd = new VariableDeclaration (d.Variable, type_expr.Location);
+                                       var vd = new VariableDeclaration (d.Variable, d.Variable.Location);
                                        vd.Initializer = d.Initializer;
                                        vd.IsNested = true;
                                        vd.dispose_call = CreateDisposeCall (bc, d.Variable);
@@ -5518,6 +5766,14 @@ namespace Mono.CSharp {
 
                #endregion
 
+               public override void Emit (EmitContext ec)
+               {
+                       //
+                       // Don't emit sequence point it will be set on variable declaration
+                       //
+                       DoEmit (ec);
+               }
+
                protected override void EmitTryBodyPrepare (EmitContext ec)
                {
                        decl.Emit (ec);
@@ -5529,7 +5785,7 @@ namespace Mono.CSharp {
                        stmt.Emit (ec);
                }
 
-               protected override void EmitFinallyBody (EmitContext ec)
+               public override void EmitFinallyBody (EmitContext ec)
                {
                        decl.EmitDispose (ec);
                }
@@ -5595,27 +5851,43 @@ namespace Mono.CSharp {
        /// </summary>
        public class Foreach : Statement
        {
-               sealed class ArrayForeach : Statement
+               abstract class IteratorStatement : Statement
                {
-                       readonly Foreach for_each;
-                       readonly Statement statement;
+                       protected readonly Foreach for_each;
+
+                       protected IteratorStatement (Foreach @foreach)
+                       {
+                               this.for_each = @foreach;
+                               this.loc = @foreach.expr.Location;
+                       }
+
+                       protected override void CloneTo (CloneContext clonectx, Statement target)
+                       {
+                               throw new NotImplementedException ();
+                       }
 
-                       Expression conv;
+                       public override void Emit (EmitContext ec)
+                       {
+                               if (ec.EmitAccurateDebugInfo) {
+                                       ec.Emit (OpCodes.Nop);
+                               }
+
+                               base.Emit (ec);
+                       }
+               }
+
+               sealed class ArrayForeach : IteratorStatement
+               {
                        TemporaryVariableReference[] lengths;
                        Expression [] length_exprs;
                        StatementExpression[] counter;
                        TemporaryVariableReference[] variables;
 
                        TemporaryVariableReference copy;
-                       Expression access;
-                       LocalVariableReference variable;
 
                        public ArrayForeach (Foreach @foreach, int rank)
+                               : base (@foreach)
                        {
-                               for_each = @foreach;
-                               statement = for_each.statement;
-                               loc = @foreach.loc;
-
                                counter = new StatementExpression[rank];
                                variables = new TemporaryVariableReference[rank];
                                length_exprs = new Expression [rank];
@@ -5628,11 +5900,6 @@ namespace Mono.CSharp {
                                        lengths = new TemporaryVariableReference [rank];
                        }
 
-                       protected override void CloneTo (CloneContext clonectx, Statement target)
-                       {
-                               throw new NotImplementedException ();
-                       }
-
                        public override bool Resolve (BlockContext ec)
                        {
                                Block variables_block = for_each.variable.Block;
@@ -5644,7 +5911,7 @@ namespace Mono.CSharp {
                                for (int i = 0; i < rank; i++) {
                                        var v = TemporaryVariableReference.Create (ec.BuiltinTypes.Int, variables_block, loc);
                                        variables[i] = v;
-                                       counter[i] = new StatementExpression (new UnaryMutator (UnaryMutator.Mode.PostIncrement, v, loc));
+                                       counter[i] = new StatementExpression (new UnaryMutator (UnaryMutator.Mode.PostIncrement, v, Location.Null));
                                        counter[i].Resolve (ec);
 
                                        if (rank == 1) {
@@ -5661,7 +5928,7 @@ namespace Mono.CSharp {
                                        list.Add (new Argument (v));
                                }
 
-                               access = new ElementAccess (copy, list, loc).Resolve (ec);
+                               var access = new ElementAccess (copy, list, loc).Resolve (ec);
                                if (access == null)
                                        return false;
 
@@ -5671,26 +5938,30 @@ namespace Mono.CSharp {
                                        var_type = access.Type;
                                } else {
                                        var_type = for_each.type.ResolveAsType (ec);
+
+                                       if (var_type == null)
+                                               return false;
+
+                                       access = Convert.ExplicitConversion (ec, access, var_type, loc);
+                                       if (access == null)
+                                               return false;
                                }
 
-                               if (var_type == null)
-                                       return false;
+                               for_each.variable.Type = var_type;
 
-                               conv = Convert.ExplicitConversion (ec, access, var_type, loc);
-                               if (conv == null)
+                               var variable_ref = new LocalVariableReference (for_each.variable, loc).Resolve (ec);
+                               if (variable_ref == null)
                                        return false;
 
+                               for_each.body.AddScopeStatement (new StatementExpression (new CompilerAssign (variable_ref, access, Location.Null), for_each.type.Location));
+
                                bool ok = true;
 
                                ec.StartFlowBranching (FlowBranching.BranchingType.Loop, loc);
                                ec.CurrentBranching.CreateSibling ();
 
-                               for_each.variable.Type = conv.Type;
-                               variable = new LocalVariableReference (for_each.variable, loc);
-                               variable.Resolve (ec);
-
                                ec.StartFlowBranching (FlowBranching.BranchingType.Embedded, loc);
-                               if (!statement.Resolve (ec))
+                               if (!for_each.body.Resolve (ec))
                                        ok = false;
                                ec.EndFlowBranching ();
 
@@ -5726,12 +5997,10 @@ namespace Mono.CSharp {
                                        ec.MarkLabel (loop [i]);
                                }
 
-                               variable.local_info.CreateBuilder (ec);
-                               variable.EmitAssign (ec, conv, false, false);
-
-                               statement.Emit (ec);
+                               for_each.body.Emit (ec);
 
                                ec.MarkLabel (ec.LoopBegin);
+                               ec.Mark (for_each.expr.Location);
 
                                for (int i = rank - 1; i >= 0; i--){
                                        counter [i].Emit (ec);
@@ -5751,59 +6020,8 @@ namespace Mono.CSharp {
                        }
                }
 
-               sealed class CollectionForeach : Statement, OverloadResolver.IErrorHandler
+               sealed class CollectionForeach : IteratorStatement, OverloadResolver.IErrorHandler
                {
-                       class Body : Statement
-                       {
-                               TypeSpec type;
-                               LocalVariableReference variable;
-                               Expression current, conv;
-                               Statement statement;
-
-                               public Body (TypeSpec type, LocalVariable variable,
-                                                                  Expression current, Statement statement,
-                                                                  Location loc)
-                               {
-                                       this.type = type;
-                                       this.variable = new LocalVariableReference (variable, loc);
-                                       this.current = current;
-                                       this.statement = statement;
-                                       this.loc = loc;
-                               }
-
-                               protected override void CloneTo (CloneContext clonectx, Statement target)
-                               {
-                                       throw new NotImplementedException ();
-                               }
-
-                               public override bool Resolve (BlockContext ec)
-                               {
-                                       current = current.Resolve (ec);
-                                       if (current == null)
-                                               return false;
-
-                                       conv = Convert.ExplicitConversion (ec, current, type, loc);
-                                       if (conv == null)
-                                               return false;
-
-                                       variable.local_info.Type = conv.Type;
-                                       variable.Resolve (ec);
-
-                                       if (!statement.Resolve (ec))
-                                               return false;
-
-                                       return true;
-                               }
-
-                               protected override void DoEmit (EmitContext ec)
-                               {
-                                       variable.local_info.CreateBuilder (ec);
-                                       variable.EmitAssign (ec, conv, false, false);
-
-                                       statement.Emit (ec);
-                               }
-                       }
-
                        class RuntimeDispose : Using.VariableDeclaration
                        {
                                public RuntimeDispose (LocalVariable lv, Location loc)
@@ -5831,7 +6049,7 @@ namespace Mono.CSharp {
                                        var idisaposable_test = new Binary (Binary.Operator.Inequality, new CompilerAssign (
                                                dispose_variable.CreateReferenceExpression (bc, loc),
                                                new As (lv.CreateReferenceExpression (bc, loc), new TypeExpression (dispose_variable.Type, loc), loc),
-                                               loc), new NullLiteral (loc), loc);
+                                               loc), new NullLiteral (loc));
 
                                        var m = bc.Module.PredefinedMembers.IDisposableDispose.Resolve (loc);
 
@@ -5846,23 +6064,15 @@ namespace Mono.CSharp {
                        LocalVariable variable;
                        Expression expr;
                        Statement statement;
-                       Expression var_type;
                        ExpressionStatement init;
                        TemporaryVariableReference enumerator_variable;
                        bool ambiguous_getenumerator_name;
 
-                       public CollectionForeach (Expression var_type, LocalVariable var, Expression expr, Statement stmt, Location l)
+                       public CollectionForeach (Foreach @foreach, LocalVariable var, Expression expr)
+                               : base (@foreach)
                        {
-                               this.var_type = var_type;
                                this.variable = var;
                                this.expr = expr;
-                               statement = stmt;
-                               loc = l;
-                       }
-
-                       protected override void CloneTo (CloneContext clonectx, Statement target)
-                       {
-                               throw new NotImplementedException ();
                        }
 
                        void Error_WrongEnumerator (ResolveContext rc, MethodSpec enumerator)
@@ -5970,7 +6180,7 @@ namespace Mono.CSharp {
                                        return null;
                                }
 
-                               return MethodGroupExpr.CreatePredefined (ms, enumerator.ReturnType, loc);
+                               return MethodGroupExpr.CreatePredefined (ms, enumerator.ReturnType, expr.Location);
                        }
 
                        PropertySpec ResolveCurrent (ResolveContext rc, MethodSpec enumerator)
@@ -6024,7 +6234,7 @@ namespace Mono.CSharp {
                                if (current_pe == null)
                                        return false;
 
-                               VarExpr ve = var_type as VarExpr;
+                               VarExpr ve = for_each.type as VarExpr;
 
                                if (ve != null) {
                                        if (is_dynamic) {
@@ -6040,16 +6250,26 @@ namespace Mono.CSharp {
                                                current_pe = EmptyCast.Create (current_pe, ec.BuiltinTypes.Dynamic);
                                        }
 
-                                       variable.Type = var_type.ResolveAsType (ec);
+                                       variable.Type = for_each.type.ResolveAsType (ec);
+
+                                       if (variable.Type == null)
+                                               return false;
+
+                                       current_pe = Convert.ExplicitConversion (ec, current_pe, variable.Type, loc);
+                                       if (current_pe == null)
+                                               return false;
                                }
 
-                               if (variable.Type == null)
+                               var variable_ref = new LocalVariableReference (variable, loc).Resolve (ec);
+                               if (variable_ref == null)
                                        return false;
 
+                               for_each.body.AddScopeStatement (new StatementExpression (new CompilerAssign (variable_ref, current_pe, Location.Null), for_each.type.Location));
+
                                var init = new Invocation (get_enumerator_mg, null);
 
                                statement = new While (new BooleanExpression (new Invocation (move_next_mg, null)),
-                                       new Body (variable.Type, variable, current_pe, statement, loc), loc);
+                                        for_each.body, Location.Null);
 
                                var enum_type = enumerator_variable.Type;
 
@@ -6061,23 +6281,23 @@ namespace Mono.CSharp {
                                                //
                                                // Runtime Dispose check
                                                //
-                                               var vd = new RuntimeDispose (enumerator_variable.LocalInfo, loc);
+                                               var vd = new RuntimeDispose (enumerator_variable.LocalInfo, Location.Null);
                                                vd.Initializer = init;
-                                               statement = new Using (vd, statement, loc);
+                                               statement = new Using (vd, statement, Location.Null);
                                        } else {
                                                //
                                                // No Dispose call needed
                                                //
-                                               this.init = new SimpleAssign (enumerator_variable, init);
+                                               this.init = new SimpleAssign (enumerator_variable, init, Location.Null);
                                                this.init.Resolve (ec);
                                        }
                                } else {
                                        //
                                        // Static Dispose check
                                        //
-                                       var vd = new Using.VariableDeclaration (enumerator_variable.LocalInfo, loc);
+                                       var vd = new Using.VariableDeclaration (enumerator_variable.LocalInfo, Location.Null);
                                        vd.Initializer = init;
-                                       statement = new Using (vd, statement, loc);
+                                       statement = new Using (vd, statement, Location.Null);
                                }
 
                                return statement.Resolve (ec);
@@ -6098,7 +6318,7 @@ namespace Mono.CSharp {
                        bool OverloadResolver.IErrorHandler.AmbiguousCandidates (ResolveContext ec, MemberSpec best, MemberSpec ambiguous)
                        {
                                ec.Report.SymbolRelatedToPreviousError (best);
-                               ec.Report.Warning (278, 2, loc,
+                               ec.Report.Warning (278, 2, expr.Location,
                                        "`{0}' contains ambiguous implementation of `{1}' pattern. Method `{2}' is ambiguous with method `{3}'",
                                        expr.Type.GetSignatureForError (), "enumerable",
                                        best.GetSignatureForError (), ambiguous.GetSignatureForError ());
@@ -6129,13 +6349,15 @@ namespace Mono.CSharp {
                LocalVariable variable;
                Expression expr;
                Statement statement;
+               Block body;
 
-               public Foreach (Expression type, LocalVariable var, Expression expr, Statement stmt, Location l)
+               public Foreach (Expression type, LocalVariable var, Expression expr, Statement stmt, Block body, Location l)
                {
                        this.type = type;
                        this.variable = var;
                        this.expr = expr;
-                       statement = stmt;
+                       this.statement = stmt;
+                       this.body = body;
                        loc = l;
                }
 
@@ -6155,7 +6377,6 @@ namespace Mono.CSharp {
                        get { return variable; }
                }
 
-
                public override bool Resolve (BlockContext ec)
                {
                        expr = expr.Resolve (ec);
@@ -6167,6 +6388,8 @@ namespace Mono.CSharp {
                                return false;
                        }
 
+                       body.AddStatement (statement);
+
                        if (expr.Type.BuiltinType == BuiltinTypeSpec.Type.String) {
                                statement = new ArrayForeach (this, 1);
                        } else if (expr.Type is ArrayContainer) {
@@ -6178,7 +6401,7 @@ namespace Mono.CSharp {
                                        return false;
                                }
 
-                               statement = new CollectionForeach (type, variable, expr, statement, loc);
+                               statement = new CollectionForeach (this, variable, expr);
                        }
 
                        return statement.Resolve (ec);
@@ -6186,6 +6409,8 @@ namespace Mono.CSharp {
 
                protected override void DoEmit (EmitContext ec)
                {
+                       variable.CreateBuilder (ec);
+
                        Label old_begin = ec.LoopBegin, old_end = ec.LoopEnd;
                        ec.LoopBegin = ec.DefineLabel ();
                        ec.LoopEnd = ec.DefineLabel ();
@@ -6202,6 +6427,7 @@ namespace Mono.CSharp {
 
                        target.type = type.Clone (clonectx);
                        target.expr = expr.Clone (clonectx);
+                       target.body = (Block) body.Clone (clonectx);
                        target.statement = statement.Clone (clonectx);
                }