Enabling #nullable for operator surface.

Rx.NET/Source/src/System.Reactive/Linq/GroupedObservable.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Disposables;
 using System.Reactive.Subjects;
 
@@ -12,7 +10,7 @@ namespace System.Reactive.Linq
     internal sealed class GroupedObservable<TKey, TElement> : ObservableBase<TElement>, IGroupedObservable<TKey, TElement>
     {
         private readonly IObservable<TElement> _subject;
-        private readonly RefCountDisposable _refCount;
+        private readonly RefCountDisposable? _refCount;
 
         public GroupedObservable(TKey key, ISubject<TElement> subject, RefCountDisposable refCount)
         {

Rx.NET/Source/src/System.Reactive/Linq/IQueryLanguage.Generated.cs

@@ -2,15 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 namespace System.Reactive.Linq
 {
     partial interface IQueryLanguage
     {
         /* The following code is generated by a T4 template. */
 
-        #region CombineLatest and Zip auto-generated code (09/25/2020 14:09:18)
+        #region CombineLatest and Zip auto-generated code (10/01/2020 16:25:46)
 
         IObservable<TResult> CombineLatest<T1, T2, TResult>(IObservable<T1> source1, IObservable<T2> source2, Func<T1, T2, TResult> resultSelector);
         IObservable<TResult> CombineLatest<T1, T2, T3, TResult>(IObservable<T1> source1, IObservable<T2> source2, IObservable<T3> source3, Func<T1, T2, T3, TResult> resultSelector);

Rx.NET/Source/src/System.Reactive/Linq/IQueryLanguage.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Concurrency;
@@ -145,10 +143,10 @@ namespace System.Reactive.Linq
         IObservable<int?> Sum<TSource>(IObservable<TSource> source, Func<TSource, int?> selector);
         IObservable<long?> Sum<TSource>(IObservable<TSource> source, Func<TSource, long?> selector);
         IObservable<TSource[]> ToArray<TSource>(IObservable<TSource> source);
-        IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer);
-        IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector);
-        IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer);
-        IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector);
+        IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer) where TKey : notnull;
+        IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector) where TKey : notnull;
+        IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer) where TKey : notnull;
+        IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector) where TKey : notnull;
         IObservable<IList<TSource>> ToList<TSource>(IObservable<TSource> source);
         IObservable<ILookup<TKey, TElement>> ToLookup<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer);
         IObservable<ILookup<TKey, TSource>> ToLookup<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer);
@@ -159,37 +157,37 @@ namespace System.Reactive.Linq
 
         #region * Async *
 
-        Func<IObservable<TResult>> FromAsyncPattern<TResult>(Func<AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, IObservable<TResult>> FromAsyncPattern<T1, TResult>(Func<T1, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, IObservable<TResult>> FromAsyncPattern<T1, T2, TResult>(Func<T1, T2, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, TResult>(Func<T1, T2, T3, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, TResult>(Func<T1, T2, T3, T4, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, TResult>(Func<T1, T2, T3, T4, T5, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, TResult>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
-
-        Func<IObservable<Unit>> FromAsyncPattern(Func<AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, IObservable<Unit>> FromAsyncPattern<T1>(Func<T1, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, IObservable<Unit>> FromAsyncPattern<T1, T2>(Func<T1, T2, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, IObservable<Unit>> FromAsyncPattern<T1, T2, T3>(Func<T1, T2, T3, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4>(Func<T1, T2, T3, T4, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5>(Func<T1, T2, T3, T4, T5, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
-        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<IObservable<TResult>> FromAsyncPattern<TResult>(Func<AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, IObservable<TResult>> FromAsyncPattern<T1, TResult>(Func<T1, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, IObservable<TResult>> FromAsyncPattern<T1, T2, TResult>(Func<T1, T2, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, TResult>(Func<T1, T2, T3, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, TResult>(Func<T1, T2, T3, T4, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, TResult>(Func<T1, T2, T3, T4, T5, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, TResult>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end);
+
+        Func<IObservable<Unit>> FromAsyncPattern(Func<AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, IObservable<Unit>> FromAsyncPattern<T1>(Func<T1, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, IObservable<Unit>> FromAsyncPattern<T1, T2>(Func<T1, T2, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, IObservable<Unit>> FromAsyncPattern<T1, T2, T3>(Func<T1, T2, T3, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4>(Func<T1, T2, T3, T4, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5>(Func<T1, T2, T3, T4, T5, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
+        Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end);
 
         IObservable<TSource> Start<TSource>(Func<TSource> function);
         IObservable<TSource> Start<TSource>(Func<TSource> function, IScheduler scheduler);
@@ -329,7 +327,7 @@ namespace System.Reactive.Linq
         IObservable<TResult> Replay<TSource, TResult>(IObservable<TSource> source, Func<IObservable<TSource>, IObservable<TResult>> selector, int bufferSize, TimeSpan window);
         IConnectableObservable<TSource> Replay<TSource>(IObservable<TSource> source, int bufferSize, TimeSpan window, IScheduler scheduler);
         IObservable<TResult> Replay<TSource, TResult>(IObservable<TSource> source, Func<IObservable<TSource>, IObservable<TResult>> selector, int bufferSize, TimeSpan window, IScheduler scheduler);
-        IObservable<TSource> AutoConnect<TSource>(IConnectableObservable<TSource> source, int minObservers, Action<IDisposable> onConnect);
+        IObservable<TSource> AutoConnect<TSource>(IConnectableObservable<TSource> source, int minObservers, Action<IDisposable>? onConnect);
 
         #endregion
 
@@ -465,9 +463,9 @@ namespace System.Reactive.Linq
         Task ForEachAsync<TSource>(IObservable<TSource> source, Action<TSource, int> onNext);
         Task ForEachAsync<TSource>(IObservable<TSource> source, Action<TSource, int> onNext, CancellationToken cancellationToken);
 
-        IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IObservable<TResult> defaultSource);
-        IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IScheduler scheduler);
-        IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources);
+        IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IObservable<TResult> defaultSource) where TValue : notnull;
+        IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IScheduler scheduler) where TValue : notnull;
+        IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources) where TValue : notnull;
         IObservable<TSource> DoWhile<TSource>(IObservable<TSource> source, Func<bool> condition);
         IObservable<TResult> For<TSource, TResult>(IEnumerable<TSource> source, Func<TSource, IObservable<TResult>> resultSelector);
         IObservable<TResult> If<TResult>(Func<bool> condition, IObservable<TResult> thenSource, IObservable<TResult> elseSource);

Rx.NET/Source/src/System.Reactive/Linq/IQueryLanguage.tt

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ assembly name="System.Core" #>
 <#@ import namespace="System.Linq" #>

Rx.NET/Source/src/System.Reactive/Linq/IQueryLanguageEx.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/LocalQueryMethodImplementationTypeAttribute.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.ComponentModel;
 
 namespace System.Reactive.Linq

Rx.NET/Source/src/System.Reactive/Linq/Observable.Aggregates.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 
@@ -2831,6 +2829,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="keySelector"/> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this IObservable<TSource> source, Func<TSource, TKey> keySelector)
+            where TKey : notnull
         {
             if (source == null)
             {
@@ -2857,6 +2856,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="keySelector"/> or <paramref name="comparer"/> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
+            where TKey : notnull
         {
             if (source == null)
             {
@@ -2889,6 +2889,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="keySelector"/> or <paramref name="elementSelector"/> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
+            where TKey : notnull
         {
             if (source == null)
             {
@@ -2922,6 +2923,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="keySelector"/> or <paramref name="elementSelector"/> or <paramref name="comparer"/> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
+            where TKey : notnull
         {
             if (source == null)
             {

Rx.NET/Source/src/System.Reactive/Linq/Observable.Async.cs

@@ -2,13 +2,10 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Threading;
 using System.Threading.Tasks;
 
-
 namespace System.Reactive.Linq
 {
     public static partial class Observable
@@ -27,7 +24,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<IObservable<TResult>> FromAsyncPattern<TResult>(Func<AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<IObservable<TResult>> FromAsyncPattern<TResult>(Func<AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -53,7 +50,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, IObservable<TResult>> FromAsyncPattern<TArg1, TResult>(Func<TArg1, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, IObservable<TResult>> FromAsyncPattern<TArg1, TResult>(Func<TArg1, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -80,7 +77,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TResult>(Func<TArg1, TArg2, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TResult>(Func<TArg1, TArg2, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -108,7 +105,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TResult>(Func<TArg1, TArg2, TArg3, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TResult>(Func<TArg1, TArg2, TArg3, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -137,7 +134,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TResult>(Func<TArg1, TArg2, TArg3, TArg4, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TResult>(Func<TArg1, TArg2, TArg3, TArg4, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -167,7 +164,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -198,7 +195,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -230,7 +227,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -263,7 +260,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -297,7 +294,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -332,7 +329,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -368,7 +365,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -405,7 +402,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -443,7 +440,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -482,7 +479,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TResult>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             if (begin == null)
             {
@@ -510,7 +507,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<IObservable<Unit>> FromAsyncPattern(Func<AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<IObservable<Unit>> FromAsyncPattern(Func<AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -535,7 +532,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, IObservable<Unit>> FromAsyncPattern<TArg1>(Func<TArg1, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, IObservable<Unit>> FromAsyncPattern<TArg1>(Func<TArg1, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -561,7 +558,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2>(Func<TArg1, TArg2, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2>(Func<TArg1, TArg2, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -588,7 +585,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3>(Func<TArg1, TArg2, TArg3, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3>(Func<TArg1, TArg2, TArg3, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -616,7 +613,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4>(Func<TArg1, TArg2, TArg3, TArg4, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4>(Func<TArg1, TArg2, TArg3, TArg4, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -645,7 +642,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -675,7 +672,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -706,7 +703,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -738,7 +735,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -771,7 +768,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -805,7 +802,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -840,7 +837,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -876,7 +873,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -913,7 +910,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {
@@ -951,7 +948,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException"><paramref name="begin"/> or <paramref name="end"/> is null.</exception>
         /// <remarks>Each invocation of the resulting function will cause the asynchronous operation to be started. Subscription to the resulting sequence has no observable side-effect, and each subscription will produce the asynchronous operation's result.</remarks>
         [Obsolete(Constants_Linq.UseTaskFromAsyncPattern)]
-        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public static Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, IObservable<Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14>(Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             if (begin == null)
             {

Rx.NET/Source/src/System.Reactive/Linq/Observable.Awaiter.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Subjects;
 using System.Threading;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable.Binding.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Reactive.Subjects;
 
@@ -395,7 +393,7 @@ namespace System.Reactive.Linq
         /// <param name="onConnect">If not null, the connection's IDisposable is provided to it.</param>
         /// <returns>An observable sequence that connects to the source at most once when the given number of observers have subscribed to it.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="source"/> is null.</exception>
-        public static IObservable<TSource> AutoConnect<TSource>(this IConnectableObservable<TSource> source, int minObservers = 1, Action<IDisposable> onConnect = null)
+        public static IObservable<TSource> AutoConnect<TSource>(this IConnectableObservable<TSource> source, int minObservers = 1, Action<IDisposable>? onConnect = null)
         {
             if (source == null)
             {

Rx.NET/Source/src/System.Reactive/Linq/Observable.Blocking.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 
 namespace System.Reactive.Linq

Rx.NET/Source/src/System.Reactive/Linq/Observable.Concurrency.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Threading;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable.Conversions.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable.Creation.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Threading;
 using System.Threading.Tasks;

Rx.NET/Source/src/System.Reactive/Linq/Observable.Events.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Threading;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable.Imperative.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 using System.Threading;
@@ -130,6 +128,7 @@ namespace System.Reactive.Linq
         /// <returns>The observable sequence retrieved from the <paramref name="sources"/> dictionary based on the <paramref name="selector"/> invocation result, or <paramref name="defaultSource"/> if no match is found.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="selector"/> or <paramref name="sources"/> or <paramref name="defaultSource"/> is null.</exception>
         public static IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IObservable<TResult> defaultSource)
+            where TValue : notnull
         {
             if (selector == null)
             {
@@ -160,6 +159,7 @@ namespace System.Reactive.Linq
         /// <returns>The observable sequence retrieved from the <paramref name="sources"/> dictionary based on the <paramref name="selector"/> invocation result, or an empty sequence if no match is found.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="selector"/> or <paramref name="sources"/> or <paramref name="scheduler"/> is null.</exception>
         public static IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IScheduler scheduler)
+            where TValue : notnull
         {
             if (selector == null)
             {
@@ -189,6 +189,7 @@ namespace System.Reactive.Linq
         /// <returns>The observable sequence retrieved from the <paramref name="sources"/> dictionary based on the <paramref name="selector"/> invocation result, or an empty sequence if no match is found.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="selector"/> or <paramref name="sources"/> is null.</exception>
         public static IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources)
+            where TValue : notnull
         {
             if (selector == null)
             {

Rx.NET/Source/src/System.Reactive/Linq/Observable.Joins.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Joins;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable.Multiple.CombineLatest.Generated.cs

@@ -2,15 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 namespace System.Reactive.Linq
 {
     public static partial class Observable
     {
         /* The following code is generated by a T4 template. */
 
-        #region CombineLatest auto-generated code (09/25/2020 12:10:41)
+        #region CombineLatest auto-generated code (10/01/2020 16:33:15)
 
         /// <summary>
         /// Merges the specified observable sequences into one observable sequence by using the selector function whenever any of the observable sequences produces an element.

Rx.NET/Source/src/System.Reactive/Linq/Observable.Multiple.CombineLatest.tt

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ assembly name="System.Core" #>
 <#@ import namespace="System.Linq" #>

Rx.NET/Source/src/System.Reactive/Linq/Observable.Multiple.Zip.Generated.cs

@@ -2,15 +2,13 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 namespace System.Reactive.Linq
 {
     public static partial class Observable
     {
         /* The following code is generated by a T4 template. */
 
-        #region Zip auto-generated code (09/25/2020 12:10:41)
+        #region Zip auto-generated code (10/01/2020 16:33:19)
 
         /// <summary>
         /// Merges the specified observable sequences into one observable sequence by using the selector function whenever all of the observable sequences have produced an element at a corresponding index.

Rx.NET/Source/src/System.Reactive/Linq/Observable.Multiple.Zip.tt

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ assembly name="System.Core" #>
 <#@ import namespace="System.Linq" #>

Rx.NET/Source/src/System.Reactive/Linq/Observable.Multiple.cs

@@ -2,11 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
-using System.Threading; // Used in XML doc comments
+using System.Threading;
 using System.Threading.Tasks;
 
 namespace System.Reactive.Linq

Rx.NET/Source/src/System.Reactive/Linq/Observable.Queryable.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 #pragma warning disable 1591
 
 namespace System.Reactive.Linq
@@ -11,7 +9,7 @@ namespace System.Reactive.Linq
     public static partial class Qbservable
     {
 #pragma warning disable IDE1006 // Naming Styles: 3rd party code is known to reflect for this specific field name
-        private static IQbservableProvider s_provider;
+        private static IQbservableProvider? s_provider;
 #pragma warning restore IDE1006 // Naming Styles
 
         /// <summary>

Rx.NET/Source/src/System.Reactive/Linq/Observable.Single.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable.StandardSequenceOperators.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 using System.Reactive.Threading.Tasks; // needed for doc comments

Rx.NET/Source/src/System.Reactive/Linq/Observable.Time.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable/DefaultIfEmpty.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 namespace System.Reactive.Linq.ObservableImpl
 {
     internal sealed class DefaultIfEmpty<TSource> : Producer<TSource, DefaultIfEmpty<TSource>._>

Rx.NET/Source/src/System.Reactive/Linq/ObservableEx.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/Observable_.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 namespace System.Reactive.Linq
 {
     /// <summary>

Rx.NET/Source/src/System.Reactive/Linq/Qbservable.Generated.cs

@@ -3,8 +3,6 @@
  * Run Rx's auto-homoiconizer tool to generate this file (in the HomoIcon directory).
  */
 
- #nullable disable
-
 #pragma warning disable 1591
 
 using System.Collections.Generic;
@@ -1428,6 +1426,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException">
         /// <paramref name="selector" /> or <paramref name="sources" /> is null.</exception>
         public static IQbservable<TResult> Case<TValue, TResult>(this IQbservableProvider provider, Expression<Func<TValue>> selector, IDictionary<TValue, IObservable<TResult>> sources)
+            where TValue : notnull
         {
             if (provider == null)
                 throw new ArgumentNullException(nameof(provider));
@@ -1464,6 +1463,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException">
         /// <paramref name="selector" /> or <paramref name="sources" /> or <paramref name="defaultSource" /> is null.</exception>
         public static IQbservable<TResult> Case<TValue, TResult>(this IQbservableProvider provider, Expression<Func<TValue>> selector, IDictionary<TValue, IObservable<TResult>> sources, IObservable<TResult> defaultSource)
+            where TValue : notnull
         {
             if (provider == null)
                 throw new ArgumentNullException(nameof(provider));
@@ -1503,6 +1503,7 @@ namespace System.Reactive.Linq
         /// <exception cref="ArgumentNullException">
         /// <paramref name="selector" /> or <paramref name="sources" /> or <paramref name="scheduler" /> is null.</exception>
         public static IQbservable<TResult> Case<TValue, TResult>(this IQbservableProvider provider, Expression<Func<TValue>> selector, IDictionary<TValue, IObservable<TResult>> sources, IScheduler scheduler)
+            where TValue : notnull
         {
             if (provider == null)
                 throw new ArgumentNullException(nameof(provider));
@@ -16395,6 +16396,7 @@ namespace System.Reactive.Linq
         /// <paramref name="source" /> or <paramref name="keySelector" /> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IQbservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this IQbservable<TSource> source, Expression<Func<TSource, TKey>> keySelector)
+            where TKey : notnull
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
@@ -16428,6 +16430,7 @@ namespace System.Reactive.Linq
         /// <paramref name="source" /> or <paramref name="keySelector" /> or <paramref name="comparer" /> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IQbservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this IQbservable<TSource> source, Expression<Func<TSource, TKey>> keySelector, IEqualityComparer<TKey> comparer)
+            where TKey : notnull
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
@@ -16465,6 +16468,7 @@ namespace System.Reactive.Linq
         /// <paramref name="source" /> or <paramref name="keySelector" /> or <paramref name="elementSelector" /> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IQbservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this IQbservable<TSource> source, Expression<Func<TSource, TKey>> keySelector, Expression<Func<TSource, TElement>> elementSelector)
+            where TKey : notnull
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
@@ -16503,6 +16507,7 @@ namespace System.Reactive.Linq
         /// <paramref name="source" /> or <paramref name="keySelector" /> or <paramref name="elementSelector" /> or <paramref name="comparer" /> is null.</exception>
         /// <remarks>The return type of this operator differs from the corresponding operator on IEnumerable in order to retain asynchronous behavior.</remarks>
         public static IQbservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this IQbservable<TSource> source, Expression<Func<TSource, TKey>> keySelector, Expression<Func<TSource, TElement>> elementSelector, IEqualityComparer<TKey> comparer)
+            where TKey : notnull
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));

Rx.NET/Source/src/System.Reactive/Linq/Qbservable.Joins.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 #pragma warning disable 1591
 
 using System.Collections.Generic;

Rx.NET/Source/src/System.Reactive/Linq/Qbservable.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 #pragma warning disable 1591
 
 using System.Collections.Generic;

Rx.NET/Source/src/System.Reactive/Linq/QbservableEx.Generated.cs

@@ -3,8 +3,6 @@
  * Run Rx's auto-homoiconizer tool to generate this file (in the HomoIcon directory).
  */
 
- #nullable disable
-
 #pragma warning disable 1591
 
 using System.Collections.Generic;

Rx.NET/Source/src/System.Reactive/Linq/QbservableEx.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 using System.Linq.Expressions;

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Aggregates.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 
@@ -732,21 +730,25 @@ namespace System.Reactive.Linq
         #region + ToDictionary +
 
         public virtual IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
+            where TKey : notnull
         {
             return new ToDictionary<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
         }
 
         public virtual IObservable<IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(IObservable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
+            where TKey : notnull
         {
             return new ToDictionary<TSource, TKey, TElement>(source, keySelector, elementSelector, EqualityComparer<TKey>.Default);
         }
 
         public virtual IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
+            where TKey : notnull
         {
             return new ToDictionary<TSource, TKey, TSource>(source, keySelector, x => x, comparer);
         }
 
         public virtual IObservable<IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(IObservable<TSource> source, Func<TSource, TKey> keySelector)
+            where TKey : notnull
         {
             return new ToDictionary<TSource, TKey, TSource>(source, keySelector, x => x, EqualityComparer<TKey>.Default);
         }

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Async.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Reactive.Disposables;
 using System.Reactive.Subjects;
@@ -19,7 +17,7 @@ namespace System.Reactive.Linq
 
         #region Func
 
-        public virtual Func<IObservable<TResult>> FromAsyncPattern<TResult>(Func<AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<IObservable<TResult>> FromAsyncPattern<TResult>(Func<AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return () =>
             {
@@ -55,7 +53,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, IObservable<TResult>> FromAsyncPattern<T1, TResult>(Func<T1, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, IObservable<TResult>> FromAsyncPattern<T1, TResult>(Func<T1, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return x =>
             {
@@ -87,7 +85,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, IObservable<TResult>> FromAsyncPattern<T1, T2, TResult>(Func<T1, T2, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, IObservable<TResult>> FromAsyncPattern<T1, T2, TResult>(Func<T1, T2, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y) =>
             {
@@ -119,7 +117,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, TResult>(Func<T1, T2, T3, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, TResult>(Func<T1, T2, T3, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z) =>
             {
@@ -151,7 +149,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, TResult>(Func<T1, T2, T3, T4, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, TResult>(Func<T1, T2, T3, T4, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a) =>
             {
@@ -183,7 +181,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, TResult>(Func<T1, T2, T3, T4, T5, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, TResult>(Func<T1, T2, T3, T4, T5, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b) =>
             {
@@ -215,7 +213,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, TResult>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, TResult>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c) =>
             {
@@ -247,7 +245,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d) =>
             {
@@ -279,7 +277,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e) =>
             {
@@ -311,7 +309,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e, f) =>
             {
@@ -343,7 +341,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e, f, g) =>
             {
@@ -375,7 +373,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e, f, g, h) =>
             {
@@ -407,7 +405,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e, f, g, h, i) =>
             {
@@ -439,7 +437,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e, f, g, h, i, j) =>
             {
@@ -471,7 +469,7 @@ namespace System.Reactive.Linq
             };
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<TResult>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, TResult>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object?, IAsyncResult> begin, Func<IAsyncResult, TResult> end)
         {
             return (x, y, z, a, b, c, d, e, f, g, h, i, j, k) =>
             {
@@ -507,7 +505,7 @@ namespace System.Reactive.Linq
 
         #region Action
 
-        public virtual Func<IObservable<Unit>> FromAsyncPattern(Func<AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<IObservable<Unit>> FromAsyncPattern(Func<AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -516,7 +514,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, IObservable<Unit>> FromAsyncPattern<T1>(Func<T1, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, IObservable<Unit>> FromAsyncPattern<T1>(Func<T1, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -525,7 +523,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, IObservable<Unit>> FromAsyncPattern<T1, T2>(Func<T1, T2, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, IObservable<Unit>> FromAsyncPattern<T1, T2>(Func<T1, T2, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -534,7 +532,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, IObservable<Unit>> FromAsyncPattern<T1, T2, T3>(Func<T1, T2, T3, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, IObservable<Unit>> FromAsyncPattern<T1, T2, T3>(Func<T1, T2, T3, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -543,7 +541,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4>(Func<T1, T2, T3, T4, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4>(Func<T1, T2, T3, T4, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -552,7 +550,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5>(Func<T1, T2, T3, T4, T5, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5>(Func<T1, T2, T3, T4, T5, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -561,7 +559,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6>(Func<T1, T2, T3, T4, T5, T6, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -570,7 +568,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7>(Func<T1, T2, T3, T4, T5, T6, T7, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -579,7 +577,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8>(Func<T1, T2, T3, T4, T5, T6, T7, T8, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -588,7 +586,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -597,7 +595,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -606,7 +604,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -615,7 +613,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -624,7 +622,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -633,7 +631,7 @@ namespace System.Reactive.Linq
             });
         }
 
-        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object, IAsyncResult> begin, Action<IAsyncResult> end)
+        public virtual Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, IObservable<Unit>> FromAsyncPattern<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14>(Func<T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11, T12, T13, T14, AsyncCallback, object?, IAsyncResult> begin, Action<IAsyncResult> end)
         {
             return FromAsyncPattern(begin, iar =>
             {
@@ -670,7 +668,7 @@ namespace System.Reactive.Linq
             return StartAsyncImpl(functionAsync, scheduler);
         }
 
-        private IObservable<TSource> StartAsyncImpl<TSource>(Func<Task<TSource>> functionAsync, IScheduler scheduler)
+        private IObservable<TSource> StartAsyncImpl<TSource>(Func<Task<TSource>> functionAsync, IScheduler? scheduler)
         {
             Task<TSource> task;
             try
@@ -700,7 +698,7 @@ namespace System.Reactive.Linq
             return StartAsyncImpl(functionAsync, scheduler);
         }
 
-        private IObservable<TSource> StartAsyncImpl<TSource>(Func<CancellationToken, Task<TSource>> functionAsync, IScheduler scheduler)
+        private IObservable<TSource> StartAsyncImpl<TSource>(Func<CancellationToken, Task<TSource>> functionAsync, IScheduler? scheduler)
         {
             var cancellable = new CancellationDisposable();
 
@@ -773,7 +771,7 @@ namespace System.Reactive.Linq
             return StartAsyncImpl(actionAsync, scheduler);
         }
 
-        private IObservable<Unit> StartAsyncImpl(Func<Task> actionAsync, IScheduler scheduler)
+        private IObservable<Unit> StartAsyncImpl(Func<Task> actionAsync, IScheduler? scheduler)
         {
             Task task;
             try
@@ -803,7 +801,7 @@ namespace System.Reactive.Linq
             return StartAsyncImpl(actionAsync, scheduler);
         }
 
-        private IObservable<Unit> StartAsyncImpl(Func<CancellationToken, Task> actionAsync, IScheduler scheduler)
+        private IObservable<Unit> StartAsyncImpl(Func<CancellationToken, Task> actionAsync, IScheduler? scheduler)
         {
             var cancellable = new CancellationDisposable();
 

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Awaiter.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Disposables;
 using System.Reactive.Subjects;
 using System.Threading;

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Binding.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Reactive.Subjects;
 
@@ -101,7 +99,7 @@ namespace System.Reactive.Linq
 
         #region + AutoConnect +
 
-        public virtual IObservable<TSource> AutoConnect<TSource>(IConnectableObservable<TSource> source, int minObservers = 1, Action<IDisposable> onConnect = null)
+        public virtual IObservable<TSource> AutoConnect<TSource>(IConnectableObservable<TSource> source, int minObservers = 1, Action<IDisposable>? onConnect = null)
         {
             if (minObservers <= 0)
             {

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Blocking.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Threading;
 
@@ -283,7 +281,7 @@ namespace System.Reactive.Linq
                 throw new InvalidOperationException(Strings_Linq.NO_ELEMENTS);
             }
 
-            return value;
+            return value!;
         }
 
         #endregion

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Concurrency.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Threading;
 

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Conversions.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Creation.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Reactive.Disposables;
 using System.Reactive.Threading.Tasks;
@@ -143,7 +141,7 @@ namespace System.Reactive.Linq
                 private sealed class TaskDisposeCompletionObserver : IObserver<IDisposable>, IDisposable
                 {
                     private readonly IObserver<TResult> _observer;
-                    private IDisposable _disposable;
+                    private IDisposable? _disposable;
 
                     public TaskDisposeCompletionObserver(IObserver<TResult> observer)
                     {
@@ -220,7 +218,7 @@ namespace System.Reactive.Linq
                 private sealed class TaskDisposeCompletionObserver : IObserver<Action>, IDisposable
                 {
                     private readonly IObserver<TResult> _observer;
-                    private Action _disposable;
+                    private Action? _disposable;
 
                     public TaskDisposeCompletionObserver(IObserver<TResult> observer)
                     {

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Events.cs

@@ -2,14 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Reactive.Concurrency;
 using System.Threading;
 
-#if HAS_WINRT
-#endif
-
 namespace System.Reactive.Linq
 {
     using ObservableImpl;
@@ -260,7 +255,7 @@ namespace System.Reactive.Linq
 
         #region Helper methods
 
-        private static IObservable<TResult> FromEventPattern_<TSender, TEventArgs, TResult>(Type targetType, object target, string eventName, Func<TSender, TEventArgs, TResult> getResult, IScheduler scheduler)
+        private static IObservable<TResult> FromEventPattern_<TSender, TEventArgs, TResult>(Type targetType, object? target, string eventName, Func<TSender, TEventArgs, TResult> getResult, IScheduler scheduler)
         {
             ReflectionUtils.GetEventMethods<TSender, TEventArgs>(targetType, target, eventName, out var addMethod, out var removeMethod, out var delegateType, out var isWinRT);
 

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Imperative.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 using System.Reactive.Disposables;
@@ -42,7 +40,7 @@ namespace System.Reactive.Linq
 
         private static Task ForEachAsync_<TSource>(IObservable<TSource> source, Action<TSource> onNext, CancellationToken cancellationToken)
         {
-            var tcs = new TaskCompletionSource<object>();
+            var tcs = new TaskCompletionSource<object?>();
             var subscription = new SingleAssignmentDisposable();
 
             var ctr = default(CancellationTokenRegistration);
@@ -130,16 +128,19 @@ namespace System.Reactive.Linq
         #region + Case +
 
         public virtual IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources)
+            where TValue : notnull
         {
             return Case(selector, sources, Empty<TResult>());
         }
 
         public virtual IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IScheduler scheduler)
+            where TValue : notnull
         {
             return Case(selector, sources, Empty<TResult>(scheduler));
         }
 
         public virtual IObservable<TResult> Case<TValue, TResult>(Func<TValue> selector, IDictionary<TValue, IObservable<TResult>> sources, IObservable<TResult> defaultSource)
+            where TValue : notnull
         {
             return new Case<TValue, TResult>(selector, sources, defaultSource);
         }

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Joins.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Disposables;
 using System.Reactive.Joins;

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Multiple.CombineLatest.Generated.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 namespace System.Reactive.Linq
 {
     using ObservableImpl;
@@ -12,7 +10,7 @@ namespace System.Reactive.Linq
     {
         /* The following code is generated by a T4 template. */
 
-        #region CombineLatest auto-generated code (09/25/2020 12:31:33)
+        #region CombineLatest auto-generated code (10/01/2020 16:39:47)
 
         public virtual IObservable<TResult> CombineLatest<TSource1, TSource2, TSource3, TResult>(IObservable<TSource1> source1, IObservable<TSource2> source2, IObservable<TSource3> source3, Func<TSource1, TSource2, TSource3, TResult> resultSelector)
         {

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Multiple.CombineLatest.tt

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ assembly name="System.Core" #>
 <#@ import namespace="System.Linq" #>

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Multiple.Zip.Generated.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 namespace System.Reactive.Linq
 {
     using ObservableImpl;
@@ -12,7 +10,7 @@ namespace System.Reactive.Linq
     {
         /* The following code is generated by a T4 template. */
 
-        #region Zip auto-generated code (09/25/2020 12:21:27)
+        #region Zip auto-generated code (10/01/2020 16:39:53)
 
         public virtual IObservable<TResult> Zip<TSource1, TSource2, TSource3, TResult>(IObservable<TSource1> source1, IObservable<TSource2> source2, IObservable<TSource3> source3, Func<TSource1, TSource2, TSource3, TResult> resultSelector)
         {

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Multiple.Zip.tt

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information.
 
-#nullable disable
-
 <#@ template debug="false" hostspecific="false" language="C#" #>
 <#@ assembly name="System.Core" #>
 <#@ import namespace="System.Linq" #>

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Multiple.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Concurrency;

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Single.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Concurrency;

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.StandardSequenceOperators.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 using System.Threading;
@@ -28,7 +26,7 @@ namespace System.Reactive.Linq
 
         public virtual IObservable<TSource> DefaultIfEmpty<TSource>(IObservable<TSource> source)
         {
-            return new DefaultIfEmpty<TSource>(source, default);
+            return new DefaultIfEmpty<TSource>(source, default!);
         }
 
         public virtual IObservable<TSource> DefaultIfEmpty<TSource>(IObservable<TSource> source, TSource defaultValue)

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguage.Time.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Reactive.Concurrency;
 

Rx.NET/Source/src/System.Reactive/Linq/QueryLanguageEx.cs

@@ -2,8 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT License.
 // See the LICENSE file in the project root for more information. 
 
-#nullable disable
-
 using System.Collections.Generic;
 using System.Linq;
 using System.Reactive.Concurrency;
@@ -256,7 +254,7 @@ namespace System.Reactive.Linq
                                 break;
                             case NotificationKind.OnError:
                                 rightSubscription.Dispose();
-                                observer.OnError(left.Exception);
+                                observer.OnError(left.Exception!);
                                 break;
                             case NotificationKind.OnCompleted:
                                 leftStopped = true;
@@ -275,7 +273,7 @@ namespace System.Reactive.Linq
                                         TResult result;
                                         try
                                         {
-                                            result = resultSelector(lastLeft, lastRight);
+                                            result = resultSelector(lastLeft!, lastRight!);
                                         }
                                         catch (Exception exception)
                                         {
@@ -299,7 +297,7 @@ namespace System.Reactive.Linq
                                 break;
                             case NotificationKind.OnError:
                                 leftSubscription.Dispose();
-                                observer.OnError(right.Exception);
+                                observer.OnError(right.Exception!);
                                 break;
                             case NotificationKind.OnCompleted:
                                 rightStopped = true;
@@ -318,7 +316,7 @@ namespace System.Reactive.Linq
                                         TResult result;
                                         try
                                         {
-                                            result = resultSelector(lastLeft, lastRight);
+                                            result = resultSelector(lastLeft!, lastRight!);
                                         }
                                         catch (Exception exception)
                                         {
@@ -379,7 +377,7 @@ namespace System.Reactive.Linq
                     {
                         var currentIndex = index;
                         var source = allSources[index];
-                        results.Add(default);
+                        results.Add(default!); // NB: Reserves a space; the default value gets overwritten below.
                         group.Add(source.Subscribe(
                             value =>
                             {
@@ -454,7 +452,7 @@ namespace System.Reactive.Linq
         {
             return Observable.Defer(() =>
             {
-                ChainObservable<TSource> chain = null;
+                ChainObservable<TSource>? chain = null;
 
                 return source
                     .Select(

Rx.NET/Source/tests/Tests.System.Reactive.ApiApprovals/Api/ApiApprovalTests.Core.verified.cs

@@ -868,7 +868,7 @@ namespace System.Reactive.Linq
         public static System.IObservable<TSource> Append<TSource>(this System.IObservable<TSource> source, TSource value) { }
         public static System.IObservable<TSource> Append<TSource>(this System.IObservable<TSource> source, TSource value, System.Reactive.Concurrency.IScheduler scheduler) { }
         public static System.IObservable<TSource> AsObservable<TSource>(this System.IObservable<TSource> source) { }
-        public static System.IObservable<TSource> AutoConnect<TSource>(this System.Reactive.Subjects.IConnectableObservable<TSource> source, int minObservers = 1, System.Action<System.IDisposable> onConnect = null) { }
+        public static System.IObservable<TSource> AutoConnect<TSource>(this System.Reactive.Subjects.IConnectableObservable<TSource> source, int minObservers = 1, System.Action<System.IDisposable>? onConnect = null) { }
         public static System.IObservable<decimal> Average(this System.IObservable<decimal> source) { }
         public static System.IObservable<double> Average(this System.IObservable<double> source) { }
         public static System.IObservable<double> Average(this System.IObservable<int> source) { }
@@ -900,9 +900,12 @@ namespace System.Reactive.Linq
         public static System.IObservable<System.Collections.Generic.IList<TSource>> Buffer<TSource, TBufferClosing>(this System.IObservable<TSource> source, System.Func<System.IObservable<TBufferClosing>> bufferClosingSelector) { }
         public static System.IObservable<System.Collections.Generic.IList<TSource>> Buffer<TSource, TBufferBoundary>(this System.IObservable<TSource> source, System.IObservable<TBufferBoundary> bufferBoundaries) { }
         public static System.IObservable<System.Collections.Generic.IList<TSource>> Buffer<TSource, TBufferOpening, TBufferClosing>(this System.IObservable<TSource> source, System.IObservable<TBufferOpening> bufferOpenings, System.Func<TBufferOpening, System.IObservable<TBufferClosing>> bufferClosingSelector) { }
-        public static System.IObservable<TResult> Case<TValue, TResult>(System.Func<TValue> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources) { }
-        public static System.IObservable<TResult> Case<TValue, TResult>(System.Func<TValue> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.IObservable<TResult> defaultSource) { }
-        public static System.IObservable<TResult> Case<TValue, TResult>(System.Func<TValue> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.Reactive.Concurrency.IScheduler scheduler) { }
+        public static System.IObservable<TResult> Case<TValue, TResult>(System.Func<TValue> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources)
+            where TValue :  notnull { }
+        public static System.IObservable<TResult> Case<TValue, TResult>(System.Func<TValue> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.IObservable<TResult> defaultSource)
+            where TValue :  notnull { }
+        public static System.IObservable<TResult> Case<TValue, TResult>(System.Func<TValue> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.Reactive.Concurrency.IScheduler scheduler)
+            where TValue :  notnull { }
         public static System.IObservable<TResult> Cast<TResult>(this System.IObservable<object> source) { }
         public static System.IObservable<TSource> Catch<TSource>(params System.IObservable<>[] sources) { }
         public static System.IObservable<TSource> Catch<TSource>(this System.Collections.Generic.IEnumerable<System.IObservable<TSource>> sources) { }
@@ -1047,65 +1050,65 @@ namespace System.Reactive.Linq
         public static System.IObservable<TResult> FromAsync<TResult>(System.Func<System.Threading.Tasks.Task<TResult>> functionAsync, System.Reactive.Concurrency.IScheduler scheduler) { }
         public static System.IObservable<TResult> FromAsync<TResult>(System.Func<System.Threading.CancellationToken, System.Threading.Tasks.Task<TResult>> functionAsync, System.Reactive.Concurrency.IScheduler scheduler) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<System.IObservable<System.Reactive.Unit>> FromAsyncPattern(System.Func<System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<System.IObservable<System.Reactive.Unit>> FromAsyncPattern(System.Func<System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<System.IObservable<TResult>> FromAsyncPattern<TResult>(System.Func<System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<System.IObservable<TResult>> FromAsyncPattern<TResult>(System.Func<System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1>(System.Func<TArg1, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1>(System.Func<TArg1, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, System.IObservable<TResult>> FromAsyncPattern<TArg1, TResult>(System.Func<TArg1, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, System.IObservable<TResult>> FromAsyncPattern<TArg1, TResult>(System.Func<TArg1, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2>(System.Func<TArg1, TArg2, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2>(System.Func<TArg1, TArg2, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TResult>(System.Func<TArg1, TArg2, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TResult>(System.Func<TArg1, TArg2, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3>(System.Func<TArg1, TArg2, TArg3, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3>(System.Func<TArg1, TArg2, TArg3, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TResult>(System.Func<TArg1, TArg2, TArg3, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TResult>(System.Func<TArg1, TArg2, TArg3, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4>(System.Func<TArg1, TArg2, TArg3, TArg4, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4>(System.Func<TArg1, TArg2, TArg3, TArg4, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.AsyncCallback, object, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.IObservable<System.Reactive.Unit>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Action<System.IAsyncResult> end) { }
         [System.Obsolete(@"This conversion is no longer supported. Replace use of the Begin/End asynchronous method pair with a new Task-based async method, and convert the result using ToObservable. If no Task-based async method is available, use Task.Factory.FromAsync to obtain a Task object.")]
-        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.AsyncCallback, object, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
+        public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.IObservable<TResult>> FromAsyncPattern<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TResult>(System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, System.AsyncCallback, object?, System.IAsyncResult> begin, System.Func<System.IAsyncResult, TResult> end) { }
         public static System.IObservable<System.Reactive.Unit> FromEvent(System.Action<System.Action> addHandler, System.Action<System.Action> removeHandler) { }
         public static System.IObservable<System.Reactive.Unit> FromEvent(System.Action<System.Action> addHandler, System.Action<System.Action> removeHandler, System.Reactive.Concurrency.IScheduler scheduler) { }
         public static System.IObservable<TEventArgs> FromEvent<TEventArgs>(System.Action<System.Action<TEventArgs>> addHandler, System.Action<System.Action<TEventArgs>> removeHandler) { }
@@ -1523,10 +1526,14 @@ namespace System.Reactive.Linq
         public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, System.IObservable<TResult>> ToAsync<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TResult>(this System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TResult> function, System.Reactive.Concurrency.IScheduler scheduler) { }
         public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, System.IObservable<TResult>> ToAsync<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult>(this System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult> function) { }
         public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, System.IObservable<TResult>> ToAsync<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult>(this System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult> function, System.Reactive.Concurrency.IScheduler scheduler) { }
-        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector) { }
-        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer) { }
-        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TElement> elementSelector) { }
-        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TElement> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer) { }
+        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector)
+            where TKey :  notnull { }
+        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer)
+            where TKey :  notnull { }
+        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TElement> elementSelector)
+            where TKey :  notnull { }
+        public static System.IObservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.IObservable<TSource> source, System.Func<TSource, TKey> keySelector, System.Func<TSource, TElement> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer)
+            where TKey :  notnull { }
         public static System.Collections.Generic.IEnumerable<TSource> ToEnumerable<TSource>(this System.IObservable<TSource> source) { }
         public static System.Reactive.IEventSource<System.Reactive.Unit> ToEvent(this System.IObservable<System.Reactive.Unit> source) { }
         public static System.Reactive.IEventSource<TSource> ToEvent<TSource>(this System.IObservable<TSource> source) { }
@@ -1688,9 +1695,12 @@ namespace System.Reactive.Linq
         public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IList<TSource>> Buffer<TSource, TBufferBoundary>(this System.Reactive.Linq.IQbservable<TSource> source, System.IObservable<TBufferBoundary> bufferBoundaries) { }
         public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IList<TSource>> Buffer<TSource, TBufferClosing>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<System.IObservable<TBufferClosing>>> bufferClosingSelector) { }
         public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IList<TSource>> Buffer<TSource, TBufferOpening, TBufferClosing>(this System.Reactive.Linq.IQbservable<TSource> source, System.IObservable<TBufferOpening> bufferOpenings, System.Linq.Expressions.Expression<System.Func<TBufferOpening, System.IObservable<TBufferClosing>>> bufferClosingSelector) { }
-        public static System.Reactive.Linq.IQbservable<TResult> Case<TValue, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TValue>> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources) { }
-        public static System.Reactive.Linq.IQbservable<TResult> Case<TValue, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TValue>> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.IObservable<TResult> defaultSource) { }
-        public static System.Reactive.Linq.IQbservable<TResult> Case<TValue, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TValue>> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.Reactive.Concurrency.IScheduler scheduler) { }
+        public static System.Reactive.Linq.IQbservable<TResult> Case<TValue, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TValue>> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources)
+            where TValue :  notnull { }
+        public static System.Reactive.Linq.IQbservable<TResult> Case<TValue, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TValue>> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.IObservable<TResult> defaultSource)
+            where TValue :  notnull { }
+        public static System.Reactive.Linq.IQbservable<TResult> Case<TValue, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TValue>> selector, System.Collections.Generic.IDictionary<TValue, System.IObservable<TResult>> sources, System.Reactive.Concurrency.IScheduler scheduler)
+            where TValue :  notnull { }
         public static System.Reactive.Linq.IQbservable<TResult> Cast<TResult>(this System.Reactive.Linq.IQbservable<object> source) { }
         public static System.Reactive.Linq.IQbservable<TSource> Catch<TSource>(this System.Reactive.Linq.IQbservableProvider provider, System.Collections.Generic.IEnumerable<System.IObservable<TSource>> sources) { }
         public static System.Reactive.Linq.IQbservable<TSource> Catch<TSource>(this System.Reactive.Linq.IQbservableProvider provider, params System.IObservable<>[] sources) { }
@@ -2230,10 +2240,14 @@ namespace System.Reactive.Linq
         public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, System.Reactive.Linq.IQbservable<TResult>> ToAsync<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TResult>> function, System.Reactive.Concurrency.IScheduler scheduler) { }
         public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, System.Reactive.Linq.IQbservable<TResult>> ToAsync<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult>> function) { }
         public static System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, System.Reactive.Linq.IQbservable<TResult>> ToAsync<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult>(this System.Reactive.Linq.IQbservableProvider provider, System.Linq.Expressions.Expression<System.Func<TArg1, TArg2, TArg3, TArg4, TArg5, TArg6, TArg7, TArg8, TArg9, TArg10, TArg11, TArg12, TArg13, TArg14, TArg15, TArg16, TResult>> function, System.Reactive.Concurrency.IScheduler scheduler) { }
-        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector) { }
-        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer) { }
-        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Linq.Expressions.Expression<System.Func<TSource, TElement>> elementSelector) { }
-        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Linq.Expressions.Expression<System.Func<TSource, TElement>> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer) { }
+        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector)
+            where TKey :  notnull { }
+        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TSource>> ToDictionary<TSource, TKey>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer)
+            where TKey :  notnull { }
+        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Linq.Expressions.Expression<System.Func<TSource, TElement>> elementSelector)
+            where TKey :  notnull { }
+        public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IDictionary<TKey, TElement>> ToDictionary<TSource, TKey, TElement>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Linq.Expressions.Expression<System.Func<TSource, TElement>> elementSelector, System.Collections.Generic.IEqualityComparer<TKey> comparer)
+            where TKey :  notnull { }
         public static System.Reactive.Linq.IQbservable<System.Collections.Generic.IList<TSource>> ToList<TSource>(this System.Reactive.Linq.IQbservable<TSource> source) { }
         public static System.Reactive.Linq.IQbservable<System.Linq.ILookup<TKey, TSource>> ToLookup<TSource, TKey>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector) { }
         public static System.Reactive.Linq.IQbservable<System.Linq.ILookup<TKey, TSource>> ToLookup<TSource, TKey>(this System.Reactive.Linq.IQbservable<TSource> source, System.Linq.Expressions.Expression<System.Func<TSource, TKey>> keySelector, System.Collections.Generic.IEqualityComparer<TKey> comparer) { }