Imported Upstream version 4.0.0~alpha1

Former-commit-id: 806294f5ded97629b74c85c09952f2a74fe182d9

external/referencesource/System.Web/Util/AppVerifierErrorCode.cs

@@ -0,0 +1,33 @@
+namespace System.Web.Util {
+    using System;
+
+    // IMPORTANT: Each error code must be used in *exactly one place* in order to make
+    // diagnosing the failure easier.
+
+    internal enum AppVerifierErrorCode {
+
+        Ok,
+
+        /* ASYNC OPERATIONS */
+        HttpApplicationInstanceWasNull,
+        BeginHandlerDelegateWasNull,
+        AsyncCallbackInvokedMultipleTimes,
+        AsyncCallbackInvokedWithNullParameter,
+        AsyncCallbackGivenAsyncResultWhichWasNotCompleted,
+        AsyncCallbackInvokedSynchronouslyButAsyncResultWasNotMarkedCompletedSynchronously,
+        AsyncCallbackInvokedAsynchronouslyButAsyncResultWasMarkedCompletedSynchronously,
+        AsyncCallbackInvokedWithUnexpectedAsyncResultInstance,
+        AsyncCallbackInvokedAsynchronouslyThenBeginHandlerThrew,
+        BeginHandlerThrewThenAsyncCallbackInvokedAsynchronously,
+        AsyncCallbackInvokedSynchronouslyThenBeginHandlerThrew,
+        AsyncCallbackInvokedWithUnexpectedAsyncResultAsyncState,
+        AsyncCallbackCalledAfterHttpApplicationReassigned,
+        BeginHandlerReturnedNull,
+        BeginHandlerReturnedAsyncResultMarkedCompletedSynchronouslyButWhichWasNotCompleted,
+        BeginHandlerReturnedAsyncResultMarkedCompletedSynchronouslyButAsyncCallbackNeverCalled,
+        BeginHandlerReturnedUnexpectedAsyncResultInstance,
+        BeginHandlerReturnedUnexpectedAsyncResultAsyncState,
+        SyncContextSendOrPostCalledAfterRequestCompleted
+
+    }
+}