Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Activities/System/Activities/ActivityWithResultWrapper.cs

@@ -0,0 +1,43 @@
+//-----------------------------------------------------------------------------
+// Copyright (c) Microsoft Corporation.  All rights reserved.
+//-----------------------------------------------------------------------------
+
+namespace System.Activities
+{
+    using System.Collections.Generic;
+    using System.Runtime;
+
+    // This wrapper is used to make our "new Expression" and "new Default" APIs
+    // work correctly even if the expression set on the base class doesn't
+    // match.  We'll log the error at cache metadata time.
+    class ActivityWithResultWrapper<T> : CodeActivity<T>, Argument.IExpressionWrapper
+    {
+        ActivityWithResult expression;
+
+        public ActivityWithResultWrapper(ActivityWithResult expression)
+        {
+            this.expression = expression;
+        }
+
+        ActivityWithResult Argument.IExpressionWrapper.InnerExpression
+        {
+            get
+            {
+                return this.expression;
+            }
+        }
+
+        protected override void CacheMetadata(CodeActivityMetadata metadata)
+        {
+            // If we've gotten here then argument validation has already
+            // logged a validation error.
+        }
+
+        protected override T Execute(CodeActivityContext context)
+        {
+            Fx.Assert("We'll never get here!");
+
+            return default(T);
+        }
+    }
+}