Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/mscorlib/system/runtime/NgenServicingAttributes.cs

@@ -0,0 +1,66 @@
+using System;
+
+namespace System.Runtime
+{
+    [AttributeUsage(AttributeTargets.Assembly, Inherited = false)]
+    public sealed class AssemblyTargetedPatchBandAttribute : Attribute
+    {
+        private String m_targetedPatchBand;
+
+        public AssemblyTargetedPatchBandAttribute(String targetedPatchBand)
+        {
+            m_targetedPatchBand = targetedPatchBand;
+        }
+
+        public String TargetedPatchBand
+        {
+            get { return m_targetedPatchBand; }
+        }
+    }
+
+// This attribute seems particularly prone to accidental inclusion in bcl.small
+// We would only want to do so intentionally (if targeted patching were enabled there)
+#if !FEATURE_CORECLR
+
+    //============================================================================================================
+    // [TargetedPatchingOptOutAttribute("Performance critical to inline across NGen image boundaries")] - 
+    // Sacrifices cheap servicing of a method body in order to allow unrestricted inlining.  Certain types of
+    // trivial methods (e.g. simple property getters) are automatically attributed by ILCA.EXE during the build.
+    // For other performance critical methods, it should be added manually.
+    //============================================================================================================
+
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor, AllowMultiple = false, Inherited = false)]
+    public sealed class TargetedPatchingOptOutAttribute : Attribute
+    {
+        private String m_reason;
+
+        public TargetedPatchingOptOutAttribute(String reason) 
+        { 
+            m_reason = reason;
+        }
+
+        public String Reason
+        {
+            get { return m_reason; }
+        }
+
+        private TargetedPatchingOptOutAttribute() { }
+    }
+
+#endif
+
+    //============================================================================================================
+    // [ForceTokenStabilization] - Using this CA forces ILCA.EXE to stabilize the attached type, method or field.
+    // We use this to identify private helper methods invoked by IL stubs.
+    //
+    // NOTE: Attaching this to a type is NOT equivalent to attaching it to all of its methods!
+    //============================================================================================================
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Interface | AttributeTargets.Delegate |
+                    AttributeTargets.Method | AttributeTargets.Constructor |
+                    AttributeTargets.Field
+                   , AllowMultiple = false, Inherited = false)]
+    sealed class ForceTokenStabilizationAttribute : Attribute
+    {
+        public ForceTokenStabilizationAttribute() { }
+    }
+}

external/referencesource/mscorlib/system/runtime/ProfileOptimization.cs

@@ -0,0 +1,59 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
+//
+// RuntimeHelpers
+//    This class defines entry point for multi-core JIT API
+//
+// Date: Oct 2010
+//
+namespace System.Runtime {
+
+    using System;
+    
+    using System.Reflection;
+
+    using System.Security;
+    using System.Security.Permissions;
+    
+    using System.Runtime;
+    using System.Runtime.InteropServices;
+    using System.Runtime.Versioning;
+    using System.Runtime.CompilerServices;
+
+#if FEATURE_MULTICOREJIT
+
+    public static class ProfileOptimization
+    {
+        [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
+        [SecurityCritical]
+        [ResourceExposure(ResourceScope.None)]
+        [SuppressUnmanagedCodeSecurity]
+        internal static extern void InternalSetProfileRoot(string directoryPath);
+
+        [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode)]
+        [SecurityCritical]
+        [ResourceExposure(ResourceScope.None)]
+        [SuppressUnmanagedCodeSecurity]
+        internal static extern void InternalStartProfile(string profile);
+
+        [SecurityCritical]
+        public static void SetProfileRoot(string directoryPath)
+        {
+            InternalSetProfileRoot(directoryPath);
+        }
+
+        [SecurityCritical]
+        public static void StartProfile(string profile)
+        {
+            InternalStartProfile(profile);
+        }
+    }
+
+#endif
+}
+

external/referencesource/mscorlib/system/runtime/compilerservices/AsyncStateMachineAttribute.cs

@@ -0,0 +1,19 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    [Serializable, AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
+    public sealed class AsyncStateMachineAttribute : StateMachineAttribute
+    {
+        public AsyncStateMachineAttribute(Type stateMachineType)
+            : base(stateMachineType)
+        {
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/CallerFilePathAttribute.cs

@@ -0,0 +1,18 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    public sealed class CallerFilePathAttribute : Attribute
+    {
+        public CallerFilePathAttribute()
+        {
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/CallerLineNumberAttribute.cs

@@ -0,0 +1,18 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    public sealed class CallerLineNumberAttribute : Attribute
+    {
+        public CallerLineNumberAttribute()
+        {
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/CallerMemberNameAttribute.cs

@@ -0,0 +1,18 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
+    public sealed class CallerMemberNameAttribute : Attribute
+    {
+        public CallerMemberNameAttribute()
+        {
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/IAsyncStateMachine.cs

@@ -0,0 +1,30 @@
+// ==++==
+//
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+//
+// IAsyncStateMachine.cs
+//
+// <OWNER>[....]</OWNER>
+//
+// Represents state machines generated for asynchronous methods.
+//
+// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// Represents state machines generated for asynchronous methods.
+    /// This type is intended for compiler use only.
+    /// </summary>
+    public interface IAsyncStateMachine
+    {
+        /// <summary>Moves the state machine to its next state.</summary>
+        void MoveNext();
+        /// <summary>Configures the state machine with a heap-allocated replica.</summary>
+        /// <param name="stateMachine">The heap-allocated replica.</param>
+        void SetStateMachine(IAsyncStateMachine stateMachine);
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/INotifyCompletion.cs

@@ -0,0 +1,43 @@
+// ==++==
+//
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
+//
+// INotifyCompletion.cs
+//
+// <OWNER>[....]</OWNER>
+//
+// Interfaces used to represent instances that notify listeners of their completion via continuations.
+// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
+
+using System;
+using System.Security;
+
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// Represents an operation that will schedule continuations when the operation completes.
+    /// </summary>
+    public interface INotifyCompletion
+    {
+        /// <summary>Schedules the continuation action to be invoked when the instance completes.</summary>
+        /// <param name="continuation">The action to invoke when the operation completes.</param>
+        /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
+        void OnCompleted(Action continuation);
+    }
+
+    /// <summary>
+    /// Represents an awaiter used to schedule continuations when an await operation completes.
+    /// </summary>
+    public interface ICriticalNotifyCompletion : INotifyCompletion
+    {
+        /// <summary>Schedules the continuation action to be invoked when the instance completes.</summary>
+        /// <param name="continuation">The action to invoke when the operation completes.</param>
+        /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
+        /// <remarks>Unlike OnCompleted, UnsafeOnCompleted need not propagate ExecutionContext information.</remarks>
+        [SecurityCritical]
+        void UnsafeOnCompleted(Action continuation);
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/IteratorStateMachineAttribute.cs

@@ -0,0 +1,19 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    [Serializable, AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
+    public sealed class IteratorStateMachineAttribute : StateMachineAttribute
+    {
+        public IteratorStateMachineAttribute(Type stateMachineType)
+            : base(stateMachineType)
+        {
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/ReferenceAssemblyAttribute.cs

@@ -0,0 +1,40 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+/*============================================================
+**
+** Attribute: ReferenceAssemblyAttribute
+**
+** Purpose: Identifies an assembly as being a "reference 
+**    assembly", meaning it contains public surface area but
+**    no usable implementation.  Reference assemblies 
+**    should be loadable for introspection, but not execution.
+**
+============================================================*/
+namespace System.Runtime.CompilerServices 
+{    
+    using System;
+    
+    [Serializable]
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple=false)]
+    public sealed class ReferenceAssemblyAttribute : Attribute
+    {
+        private String _description;  // Maybe ".NET FX v4.0 SP1, partial trust"?
+
+        public ReferenceAssemblyAttribute()
+        {
+        }
+
+        public ReferenceAssemblyAttribute(String description)
+        {
+            _description = description;
+        }
+
+        public String Description
+        {
+            get { return _description; }
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/RuntimeCompatibilityAttribute.cs

@@ -0,0 +1,50 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+////////////////////////////////////////////////////////////////////////////////
+////////////////////////////////////////////////////////////////////////////////
+/*=============================================================================
+**
+** Class: RuntimeCompatibilityAttribute
+**
+**
+** Purpose: Mark up the program to indicate various legacy or new opt-in behaviors.
+**
+**
+=============================================================================*/
+
+namespace System.Runtime.CompilerServices 
+{
+
+    using System;
+
+[Serializable]
+[AttributeUsage(AttributeTargets.Assembly, Inherited=false, AllowMultiple=false)]
+    public sealed class RuntimeCompatibilityAttribute : Attribute 
+    {
+        // fields
+        private bool m_wrapNonExceptionThrows;
+
+        // constructors
+        public RuntimeCompatibilityAttribute() {
+            // legacy behavior is the default, and m_wrapNonExceptionThrows is implicitly
+            // false thanks to the CLR's guarantee of zeroed memory.
+        }
+
+        // properties
+
+        // If a non-CLSCompliant exception (i.e. one that doesn't derive from System.Exception) is
+        // thrown, should it be wrapped up in a System.Runtime.CompilerServices.RuntimeWrappedException
+        // instance when presented to catch handlers?
+        public bool WrapNonExceptionThrows { 
+            get { 
+                return m_wrapNonExceptionThrows; 
+            }
+            set {
+                m_wrapNonExceptionThrows = value;
+            }
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/RuntimeWrappedException.cs

@@ -0,0 +1,54 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+/*=============================================================================
+**
+** Class: RuntimeWrappedException
+**
+**
+** Purpose: The exception class uses to wrap all non-CLS compliant exceptions.
+**
+**
+=============================================================================*/
+
+namespace System.Runtime.CompilerServices {
+    using System;
+    using System.Runtime.Serialization;
+    using System.Runtime.Remoting;
+    using System.Security.Permissions;
+    using System.Diagnostics.Contracts;
+        
+    [Serializable]
+    public sealed class RuntimeWrappedException : Exception
+    {
+        private RuntimeWrappedException(Object thrownObject)
+            : base(Environment.GetResourceString("RuntimeWrappedException")) {
+            SetErrorCode(System.__HResults.COR_E_RUNTIMEWRAPPED);
+            m_wrappedException = thrownObject;
+        }
+    
+        public Object WrappedException {
+            get { return m_wrappedException; }
+        }
+
+        private Object m_wrappedException;
+
+        [System.Security.SecurityCritical]  // auto-generated_required
+        public override void GetObjectData(SerializationInfo info, StreamingContext context) {
+            if (info==null) {
+                throw new ArgumentNullException("info");
+            }
+            Contract.EndContractBlock();
+            base.GetObjectData(info, context);
+            info.AddValue("WrappedException", m_wrappedException, typeof(Object));
+        }
+
+        internal RuntimeWrappedException(SerializationInfo info, StreamingContext context)
+            : base(info, context) {
+            m_wrappedException = info.GetValue("WrappedException", typeof(Object));
+        }
+    }
+}
+

external/referencesource/mscorlib/system/runtime/compilerservices/StateMachineAttribute.cs

@@ -0,0 +1,21 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+
+namespace System.Runtime.CompilerServices
+{
+    [Serializable, AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
+    public class StateMachineAttribute : Attribute
+    {
+        public Type StateMachineType { get; private set; }
+
+        public StateMachineAttribute(Type stateMachineType)
+        {
+            this.StateMachineType = stateMachineType;
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/TypeForwardedFromAttribute.cs

@@ -0,0 +1,36 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+namespace System.Runtime.CompilerServices
+{
+    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Interface | AttributeTargets.Delegate, Inherited = false, AllowMultiple = false)]
+    public sealed class TypeForwardedFromAttribute : Attribute
+    {
+        string assemblyFullName;
+
+        private TypeForwardedFromAttribute()
+        {
+            // Disallow default constructor
+        }
+
+
+        public TypeForwardedFromAttribute(string assemblyFullName)
+        {
+            if (String.IsNullOrEmpty(assemblyFullName))
+            {
+                throw new ArgumentNullException("assemblyFullName");
+            }
+            this.assemblyFullName = assemblyFullName;    
+        }
+
+        public string AssemblyFullName
+        {
+            get { 
+                return assemblyFullName; 
+            }
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/TypeForwardedToAttribute.cs

@@ -0,0 +1,48 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+
+using System;
+using System.Reflection;
+
+namespace System.Runtime.CompilerServices
+{
+    using System;
+    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple=true, Inherited=false)]
+    public sealed class TypeForwardedToAttribute : Attribute
+    {
+        private Type _destination;
+
+        public TypeForwardedToAttribute(Type destination)
+        {
+            _destination = destination;
+        }
+
+        public Type Destination
+        {
+            get {
+                return _destination;
+            }
+        }
+#if false
+        [System.Security.SecurityCritical]
+        internal static TypeForwardedToAttribute[] GetCustomAttribute(RuntimeAssembly assembly)
+        {
+            Type[] types = null;
+            RuntimeAssembly.GetForwardedTypes(assembly.GetNativeHandle(), JitHelpers.GetObjectHandleOnStack(ref types));
+
+            TypeForwardedToAttribute[] attributes = new TypeForwardedToAttribute[types.Length];
+            for (int i = 0; i < types.Length; ++i)
+                attributes[i] = new TypeForwardedToAttribute(types[i]);
+
+            return attributes;
+        }
+#endif
+    }
+}
+
+
+ 
+

external/referencesource/mscorlib/system/runtime/compilerservices/YieldAwaitable.cs

@@ -0,0 +1,166 @@
+// ==++==
+//
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
+//
+// YieldAwaitable.cs
+//
+// <OWNER>[....]</OWNER>
+//
+// Compiler-targeted type for switching back into the current execution context, e.g.
+// 
+//   await Task.Yield();
+//   =====================
+//   var $awaiter = Task.Yield().GetAwaiter();
+//   if (!$awaiter.IsCompleted)
+//   {
+//       $builder.AwaitUnsafeOnCompleted(ref $awaiter, ref this);
+//       return;
+//       Label:
+//   }
+//   $awaiter.GetResult();
+//
+// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
+
+using System;
+using System.Security;
+using System.Diagnostics;
+using System.Diagnostics.Contracts;
+using System.Diagnostics.Tracing;
+using System.Threading;
+using System.Threading.Tasks;
+using System.Security.Permissions;
+
+namespace System.Runtime.CompilerServices
+{
+    // NOTE: YieldAwaitable currently has no state; while developers are encouraged to use Task.Yield() to produce one,
+    // no validation is performed to ensure that the developer isn't doing "await new YieldAwaitable()".  Such validation
+    // would require additional, useless state to be stored, and as this is a type in the CompilerServices namespace, and
+    // as the above example isn't harmful, we take the cheaper approach of not validating anything.
+
+    /// <summary>Provides an awaitable context for switching into a target environment.</summary>
+    /// <remarks>This type is intended for compiler use only.</remarks>
+    public struct YieldAwaitable
+    {
+        /// <summary>Gets an awaiter for this <see cref="YieldAwaitable"/>.</summary>
+        /// <returns>An awaiter for this awaitable.</returns>
+        /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
+        public YieldAwaiter GetAwaiter() { return new YieldAwaiter(); }
+
+        /// <summary>Provides an awaiter that switches into a target environment.</summary>
+        /// <remarks>This type is intended for compiler use only.</remarks>
+        [HostProtection(Synchronization = true, ExternalThreading = true)]
+        public struct YieldAwaiter : ICriticalNotifyCompletion
+        {
+            /// <summary>Gets whether a yield is not required.</summary>
+            /// <remarks>This property is intended for compiler user rather than use directly in code.</remarks>
+            public bool IsCompleted { get { return false; } } // yielding is always required for YieldAwaiter, hence false
+
+            /// <summary>Posts the <paramref name="continuation"/> back to the current context.</summary>
+            /// <param name="continuation">The action to invoke asynchronously.</param>
+            /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
+            [SecuritySafeCritical]
+            public void OnCompleted(Action continuation)
+            {
+                QueueContinuation(continuation, flowContext: true);
+            }
+
+            /// <summary>Posts the <paramref name="continuation"/> back to the current context.</summary>
+            /// <param name="continuation">The action to invoke asynchronously.</param>
+            /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
+            [SecurityCritical]
+            public void UnsafeOnCompleted(Action continuation)
+            {
+                QueueContinuation(continuation, flowContext: false);
+            }
+
+            /// <summary>Posts the <paramref name="continuation"/> back to the current context.</summary>
+            /// <param name="continuation">The action to invoke asynchronously.</param>
+            /// <param name="flowContext">true to flow ExecutionContext; false if flowing is not required.</param>
+            /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
+            [SecurityCritical]
+            private static void QueueContinuation(Action continuation, bool flowContext)
+            {
+                // Validate arguments
+                if (continuation == null) throw new ArgumentNullException("continuation");
+                Contract.EndContractBlock();
+
+#if !FEATURE_PAL && !FEATURE_CORECLR    // PAL and CoreClr don't support  eventing
+                if (TplEtwProvider.Log.IsEnabled())
+                {
+                    continuation = OutputCorrelationEtwEvent(continuation);
+                }
+#endif
+                // Get the current SynchronizationContext, and if there is one,
+                // post the continuation to it.  However, treat the base type
+                // as if there wasn't a SynchronizationContext, since that's what it
+                // logically represents.
+                var syncCtx = SynchronizationContext.CurrentNoFlow;
+                if (syncCtx != null && syncCtx.GetType() != typeof(SynchronizationContext))
+                {
+                    syncCtx.Post(s_sendOrPostCallbackRunAction, continuation);
+                }
+                else
+                {
+                    // If we're targeting the default scheduler, queue to the thread pool, so that we go into the global
+                    // queue.  As we're going into the global queue, we might as well use QUWI, which for the global queue is
+                    // just a tad faster than task, due to a smaller object getting allocated and less work on the execution path.
+                    TaskScheduler scheduler = TaskScheduler.Current;
+                    if (scheduler == TaskScheduler.Default)
+                    {
+                        if (flowContext)
+                        {
+                            ThreadPool.QueueUserWorkItem(s_waitCallbackRunAction, continuation);
+                        }
+                        else
+                        {
+                            ThreadPool.UnsafeQueueUserWorkItem(s_waitCallbackRunAction, continuation);
+                        }
+                    }
+                    // We're targeting a custom scheduler, so queue a task.
+                    else
+                    {
+                        Task.Factory.StartNew(continuation, default(CancellationToken), TaskCreationOptions.PreferFairness, scheduler);
+                    }
+                }
+            }
+
+#if !FEATURE_PAL && !FEATURE_CORECLR    // PAL and CoreClr don't support  eventing
+            private static Action OutputCorrelationEtwEvent(Action continuation)
+            {
+                int continuationId = Task.NewId();
+                Task currentTask = Task.InternalCurrent;
+                // fire the correlation ETW event
+                TplEtwProvider.Log.AwaitTaskContinuationScheduled(TaskScheduler.Current.Id, (currentTask != null) ? currentTask.Id : 0, continuationId);
+
+                return AsyncMethodBuilderCore.CreateContinuationWrapper(continuation, () =>
+                {
+                    // ETW event for Task Wait End.
+                    Guid prevActivityId = new Guid();
+                    // Ensure the continuation runs under the correlated activity ID generated above
+                    EventSource.SetCurrentThreadActivityId(TplEtwProvider.CreateGuidForTaskID(continuationId), out prevActivityId);
+                    // Invoke the original continuation provided to OnCompleted.
+                    continuation();
+                    // Restore activity ID
+                    EventSource.SetCurrentThreadActivityId(prevActivityId);
+                });
+                
+            }
+#endif
+
+            /// <summary>WaitCallback that invokes the Action supplied as object state.</summary>
+            private static readonly WaitCallback s_waitCallbackRunAction = RunAction;
+            /// <summary>SendOrPostCallback that invokes the Action supplied as object state.</summary>
+            private static readonly SendOrPostCallback s_sendOrPostCallbackRunAction = RunAction;
+
+            /// <summary>Runs an Action delegate provided as state.</summary>
+            /// <param name="state">The Action delegate to invoke.</param>
+            private static void RunAction(object state) { ((Action)state)(); }
+
+            /// <summary>Ends the await operation.</summary>
+            public void GetResult() {} // Nop. It exists purely because the compiler pattern demands it.
+        }
+    }
+}

external/referencesource/mscorlib/system/runtime/compilerservices/accessedthroughpropertyattribute.cs

@@ -0,0 +1,32 @@
+// ==++==
+// 
+//   Copyright (c) Microsoft Corporation.  All rights reserved.
+// 
+// ==--==
+//------------------------------------------------------------------------------
+//------------------------------------------------------------------------------
+namespace System.Runtime.CompilerServices 
+{
+    using System;
+
+    [AttributeUsage(AttributeTargets.Field)]
+[System.Runtime.InteropServices.ComVisible(true)]
+    public sealed class AccessedThroughPropertyAttribute : Attribute
+    {
+        private readonly string propertyName;
+
+        public AccessedThroughPropertyAttribute(string propertyName)
+        {
+            this.propertyName = propertyName;
+        }
+
+        public string PropertyName 
+        {
+            get 
+            {
+                return propertyName;
+            }
+        }
+    }
+}
+