Rethrow exceptions instead of throwing them again

When an exception is thrown again ("throw ex"), its stack will be
overwritten. Instead, it should be rethrown with its original context.

More info here (Figure 2):
https://msdn.microsoft.com/en-us/magazine/mt620018.aspx

Issue #5

Author: Dan Zwell

UnityProject/Assets/Plugins/AsyncAwaitUtil/Source/IEnumeratorAwaitExtensions.cs

@@ -4,6 +4,7 @@
 using System.Linq;
 using System.Reflection;
 using System.Runtime.CompilerServices;
+using System.Runtime.ExceptionServices;
 using System.Text;
 using System.Threading;
 using UnityEngine;
@@ -154,7 +155,7 @@ public T GetResult()
 
             if (_exception != null)
             {
-                throw _exception;
+                ExceptionDispatchInfo.Capture(_exception).Throw();
             }
 
             return _result;
@@ -202,7 +203,7 @@ public void GetResult()
 
             if (_exception != null)
             {
-                throw _exception;
+                ExceptionDispatchInfo.Capture(_exception).Throw();
             }
         }
 

UnityProject/Assets/Plugins/AsyncAwaitUtil/Source/TaskExtensions.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Runtime.CompilerServices;
+using System.Runtime.ExceptionServices;
 using System.Threading.Tasks;
 using UnityEngine;
 
@@ -17,7 +18,7 @@ public static IEnumerator AsIEnumerator(this Task task)
 
         if (task.IsFaulted)
         {
-            throw task.Exception;
+            ExceptionDispatchInfo.Capture(task.Exception).Throw();
         }
     }
 
@@ -31,7 +32,7 @@ public static IEnumerator<T> AsIEnumerator<T>(this Task<T> task)
 
         if (task.IsFaulted)
         {
-            throw task.Exception;
+            ExceptionDispatchInfo.Capture(task.Exception).Throw();
         }
 
         yield return task.Result;

UnityProject/Assets/Plugins/UniRx/Scripts/Notification.cs

@@ -8,6 +8,7 @@
 using System.Diagnostics;
 using System.Globalization;
 using System.Collections.Generic;
+using System.Runtime.ExceptionServices;
 using System;
 
 #pragma warning disable 0659
@@ -270,7 +271,8 @@ public OnErrorNotification(Exception exception)
             /// <summary>
             /// Throws the exception.
             /// </summary>
-            public override T Value { get { throw exception; } }
+			// Note: the 2nd "throw" is never reached:
+            public override T Value { get { ExceptionDispatchInfo.Capture(exception).Throw(); throw null; } }
 
             /// <summary>
             /// Returns the exception.

UnityProject/Assets/Plugins/UniRx/Scripts/Observer.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.ExceptionServices;
 using System.Threading;
 
 namespace UniRx
@@ -492,7 +493,7 @@ public static IDisposable SubscribeWithState3<T, TState1, TState2, TState3>(this
     internal static class Stubs
     {
         public static readonly Action Nop = () => { };
-        public static readonly Action<Exception> Throw = ex => { throw ex; };
+        public static readonly Action<Exception> Throw = ex => { ExceptionDispatchInfo.Capture(ex).Throw(); };
 
         // marker for CatchIgnore and Catch avoid iOS AOT problem.
         public static IObservable<TSource> CatchIgnore<TSource>(Exception ex)
@@ -505,19 +506,19 @@ internal static class Stubs<T>
     {
         public static readonly Action<T> Ignore = (T t) => { };
         public static readonly Func<T, T> Identity = (T t) => t;
-        public static readonly Action<Exception, T> Throw = (ex, _) => { throw ex; };
+        public static readonly Action<Exception, T> Throw = (ex, _) => { ExceptionDispatchInfo.Capture(ex).Throw(); };
     }
 
     internal static class Stubs<T1, T2>
     {
         public static readonly Action<T1, T2> Ignore = (x, y) => { };
-        public static readonly Action<Exception, T1, T2> Throw = (ex, _, __) => { throw ex; };
+        public static readonly Action<Exception, T1, T2> Throw = (ex, _, __) => { ExceptionDispatchInfo.Capture(ex).Throw(); };
     }
 
 
     internal static class Stubs<T1, T2, T3>
     {
         public static readonly Action<T1, T2, T3> Ignore = (x, y, z) => { };
-        public static readonly Action<Exception, T1, T2, T3> Throw = (ex, _, __, ___) => { throw ex; };
+        public static readonly Action<Exception, T1, T2, T3> Throw = (ex, _, __, ___) => { ExceptionDispatchInfo.Capture(ex).Throw(); };
     }
 }

UnityProject/Assets/Plugins/UniRx/Scripts/Operators/Wait.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.ExceptionServices;
 
 namespace UniRx.Operators
 {
@@ -36,7 +37,7 @@ public T Run()
                 }
             }
 
-            if (ex != null) throw ex;
+            if (ex != null) ExceptionDispatchInfo.Capture(ex).Throw();
             if (!seenValue) throw new InvalidOperationException("No Elements.");
 
             return value;

UnityProject/Assets/Plugins/UniRx/Scripts/Subjects/AsyncSubject.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Runtime.ExceptionServices;
 using UniRx.InternalUtil;
 
 #if (ENABLE_MONO_BLEEDING_EDGE_EDITOR || ENABLE_MONO_BLEEDING_EDGE_STANDALONE)
@@ -29,7 +30,7 @@ public T Value
             {
                 ThrowIfDisposed();
                 if (!isStopped) throw new InvalidOperationException("AsyncSubject is not completed yet");
-                if (lastError != null) throw lastError;
+                if (lastError != null) ExceptionDispatchInfo.Capture(lastError).Throw();
                 return lastValue;
             }
         }
@@ -315,7 +316,7 @@ public T GetResult()
 
             if (lastError != null)
             {
-                throw lastError;
+                ExceptionDispatchInfo.Capture(lastError).Throw();
             }
 
             if (!hasValue)

UnityProject/Assets/Plugins/UniRx/Scripts/Subjects/BehaviorSubject.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Runtime.ExceptionServices;
 using UniRx.InternalUtil;
 
 namespace UniRx
@@ -23,7 +24,7 @@ public T Value
             get
             {
                 ThrowIfDisposed();
-                if (lastError != null) throw lastError;
+                if (lastError != null) ExceptionDispatchInfo.Capture(lastError).Throw();
                 return lastValue;
             }
         }

UnityProject/Assets/Plugins/UniRx/Scripts/UnityEngineBridge/MainThreadDispatcher.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Runtime.ExceptionServices;
 using System.Reflection;
 using System.Threading;
 using UniRx.InternalUtil;
@@ -444,7 +445,7 @@ public static void Initialize()
                     // Throw exception when calling from a worker thread.
                     var ex = new Exception("UniRx requires a MainThreadDispatcher component created on the main thread. Make sure it is added to the scene before calling UniRx from a worker thread.");
                     UnityEngine.Debug.LogException(ex);
-                    throw ex;
+                    ExceptionDispatchInfo.Capture(ex).Throw();
                 }
 
                 if (isQuitting)

UnityProject/Assets/Plugins/UniRx/Scripts/UnityEngineBridge/Observable.Unity.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.Runtime.ExceptionServices;
 using UniRx.Triggers;
 using UnityEngine;
 using System.Threading;
@@ -156,7 +157,7 @@ bool IEnumerator.MoveNext()
             {
                 if (reThrowOnError && HasError)
                 {
-                    throw Error;
+                    ExceptionDispatchInfo.Capture(Error).Throw();
                 }
 
                 return false;
@@ -1147,7 +1148,7 @@ static IEnumerable<IObservable<T>> RepeatInfinite<T>(IObservable<T> source)
         internal static class Stubs
         {
             public static readonly Action Nop = () => { };
-            public static readonly Action<Exception> Throw = ex => { throw ex; };
+            public static readonly Action<Exception> Throw = ex => { ExceptionDispatchInfo.Capture(ex).Throw(); };
 
             // Stubs<T>.Ignore can't avoid iOS AOT problem.
             public static void Ignore<T>(T t)