AsyncEnumerable.SingleOrDefault*Async: Fix signature for nullable.

Ix.NET/Source/System.Linq.Async.Queryable/System/Linq/AsyncQueryable.Generated.cs

@@ -4178,62 +4178,62 @@ namespace System.Linq
         
         private static MethodInfo? SingleOrDefaultAsync__TSource__2__0(Type TSource) =>
             (s_SingleOrDefaultAsync__TSource__2__0 ??
-            (s_SingleOrDefaultAsync__TSource__2__0 = new Func<IAsyncQueryable<object>, CancellationToken, ValueTask<object>>(SingleOrDefaultAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
+            (s_SingleOrDefaultAsync__TSource__2__0 = new Func<IAsyncQueryable<object>, CancellationToken, ValueTask<object?>>(SingleOrDefaultAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
 
-        public static ValueTask<TSource> SingleOrDefaultAsync<TSource>(this IAsyncQueryable<TSource> source, CancellationToken cancellationToken = default)
+        public static ValueTask<TSource?> SingleOrDefaultAsync<TSource>(this IAsyncQueryable<TSource> source, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
 
-            return source.Provider.ExecuteAsync<TSource>(Expression.Call(SingleOrDefaultAsync__TSource__2__0(typeof(TSource)), source.Expression, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
+            return source.Provider.ExecuteAsync<TSource?>(Expression.Call(SingleOrDefaultAsync__TSource__2__0(typeof(TSource)), source.Expression, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
         }
 
         private static MethodInfo? s_SingleOrDefaultAsync__TSource__3__0;
         
         private static MethodInfo? SingleOrDefaultAsync__TSource__3__0(Type TSource) =>
             (s_SingleOrDefaultAsync__TSource__3__0 ??
-            (s_SingleOrDefaultAsync__TSource__3__0 = new Func<IAsyncQueryable<object>, Expression<Func<object, bool>>, CancellationToken, ValueTask<object>>(SingleOrDefaultAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
+            (s_SingleOrDefaultAsync__TSource__3__0 = new Func<IAsyncQueryable<object>, Expression<Func<object, bool>>, CancellationToken, ValueTask<object?>>(SingleOrDefaultAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
 
-        public static ValueTask<TSource> SingleOrDefaultAsync<TSource>(this IAsyncQueryable<TSource> source, Expression<Func<TSource, bool>> predicate, CancellationToken cancellationToken = default)
+        public static ValueTask<TSource?> SingleOrDefaultAsync<TSource>(this IAsyncQueryable<TSource> source, Expression<Func<TSource, bool>> predicate, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
             if (predicate == null)
                 throw new ArgumentNullException(nameof(predicate));
 
-            return source.Provider.ExecuteAsync<TSource>(Expression.Call(SingleOrDefaultAsync__TSource__3__0(typeof(TSource)), source.Expression, predicate, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
+            return source.Provider.ExecuteAsync<TSource?>(Expression.Call(SingleOrDefaultAsync__TSource__3__0(typeof(TSource)), source.Expression, predicate, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
         }
 
         private static MethodInfo? s_SingleOrDefaultAwaitAsync__TSource__3__0;
         
         private static MethodInfo? SingleOrDefaultAwaitAsync__TSource__3__0(Type TSource) =>
             (s_SingleOrDefaultAwaitAsync__TSource__3__0 ??
-            (s_SingleOrDefaultAwaitAsync__TSource__3__0 = new Func<IAsyncQueryable<object>, Expression<Func<object, ValueTask<bool>>>, CancellationToken, ValueTask<object>>(SingleOrDefaultAwaitAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
+            (s_SingleOrDefaultAwaitAsync__TSource__3__0 = new Func<IAsyncQueryable<object>, Expression<Func<object, ValueTask<bool>>>, CancellationToken, ValueTask<object?>>(SingleOrDefaultAwaitAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
 
-        public static ValueTask<TSource> SingleOrDefaultAwaitAsync<TSource>(this IAsyncQueryable<TSource> source, Expression<Func<TSource, ValueTask<bool>>> predicate, CancellationToken cancellationToken = default)
+        public static ValueTask<TSource?> SingleOrDefaultAwaitAsync<TSource>(this IAsyncQueryable<TSource> source, Expression<Func<TSource, ValueTask<bool>>> predicate, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
             if (predicate == null)
                 throw new ArgumentNullException(nameof(predicate));
 
-            return source.Provider.ExecuteAsync<TSource>(Expression.Call(SingleOrDefaultAwaitAsync__TSource__3__0(typeof(TSource)), source.Expression, predicate, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
+            return source.Provider.ExecuteAsync<TSource?>(Expression.Call(SingleOrDefaultAwaitAsync__TSource__3__0(typeof(TSource)), source.Expression, predicate, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
         }
 
         private static MethodInfo? s_SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0;
         
         private static MethodInfo? SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0(Type TSource) =>
             (s_SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0 ??
-            (s_SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0 = new Func<IAsyncQueryable<object>, Expression<Func<object, CancellationToken, ValueTask<bool>>>, CancellationToken, ValueTask<object>>(SingleOrDefaultAwaitWithCancellationAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
+            (s_SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0 = new Func<IAsyncQueryable<object>, Expression<Func<object, CancellationToken, ValueTask<bool>>>, CancellationToken, ValueTask<object?>>(SingleOrDefaultAwaitWithCancellationAsync<object>).GetMethodInfo()!.GetGenericMethodDefinition())).MakeGenericMethod(TSource);
 
-        public static ValueTask<TSource> SingleOrDefaultAwaitWithCancellationAsync<TSource>(this IAsyncQueryable<TSource> source, Expression<Func<TSource, CancellationToken, ValueTask<bool>>> predicate, CancellationToken cancellationToken = default)
+        public static ValueTask<TSource?> SingleOrDefaultAwaitWithCancellationAsync<TSource>(this IAsyncQueryable<TSource> source, Expression<Func<TSource, CancellationToken, ValueTask<bool>>> predicate, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw new ArgumentNullException(nameof(source));
             if (predicate == null)
                 throw new ArgumentNullException(nameof(predicate));
 
-            return source.Provider.ExecuteAsync<TSource>(Expression.Call(SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0(typeof(TSource)), source.Expression, predicate, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
+            return source.Provider.ExecuteAsync<TSource?>(Expression.Call(SingleOrDefaultAwaitWithCancellationAsync__TSource__3__0(typeof(TSource)), source.Expression, predicate, Expression.Constant(cancellationToken, typeof(CancellationToken))), cancellationToken);
         }
 
         private static MethodInfo? s_Skip__TSource__2__0;

Ix.NET/Source/System.Linq.Async/System/Linq/AsyncEnumerable.AsyncOverloads.cs

@@ -79,7 +79,7 @@ namespace System.Linq
         public static IAsyncEnumerable<TResult> SelectMany<TSource, TCollection, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, ValueTask<TResult>> resultSelector) => SelectManyAwaitCore<TSource, TCollection, TResult>(source, collectionSelector, resultSelector);
         public static IAsyncEnumerable<TResult> SelectMany<TSource, TCollection, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, ValueTask<TResult>> resultSelector) => SelectManyAwaitCore<TSource, TCollection, TResult>(source, collectionSelector, resultSelector);
         public static ValueTask<TSource> SingleAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleAwaitAsyncCore<TSource>(source, predicate, cancellationToken);
-        public static ValueTask<TSource> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitAsyncCore<TSource>(source, predicate, cancellationToken);
+        public static ValueTask<TSource?> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitAsyncCore<TSource>(source, predicate, cancellationToken);
         public static IAsyncEnumerable<TSource> SkipWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate) => SkipWhileAwaitCore<TSource>(source, predicate);
         public static IAsyncEnumerable<TSource> SkipWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate) => SkipWhileAwaitCore<TSource>(source, predicate);
         public static ValueTask<long?> SumAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<long?>> selector, CancellationToken cancellationToken = default) => SumAwaitAsyncCore<TSource>(source, selector, cancellationToken);
@@ -179,7 +179,7 @@ namespace System.Linq
         public static IAsyncEnumerable<TResult> SelectMany<TSource, TCollection, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector) => SelectManyAwaitWithCancellationCore<TSource, TCollection, TResult>(source, collectionSelector, resultSelector);
         public static IAsyncEnumerable<TResult> SelectMany<TSource, TCollection, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector) => SelectManyAwaitWithCancellationCore<TSource, TCollection, TResult>(source, collectionSelector, resultSelector);
         public static ValueTask<TSource> SingleAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleAwaitWithCancellationAsyncCore<TSource>(source, predicate, cancellationToken);
-        public static ValueTask<TSource> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitWithCancellationAsyncCore<TSource>(source, predicate, cancellationToken);
+        public static ValueTask<TSource?> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitWithCancellationAsyncCore<TSource>(source, predicate, cancellationToken);
         public static IAsyncEnumerable<TSource> SkipWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate) => SkipWhileAwaitWithCancellationCore<TSource>(source, predicate);
         public static IAsyncEnumerable<TSource> SkipWhile<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate) => SkipWhileAwaitWithCancellationCore<TSource>(source, predicate);
         public static ValueTask<int?> SumAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<int?>> selector, CancellationToken cancellationToken = default) => SumAwaitWithCancellationAsyncCore<TSource>(source, selector, cancellationToken);
@@ -1001,7 +1001,7 @@ namespace System.Linq
         /// <returns>ValueTask containing the only element in the async-enumerable sequence that satisfies the condition in the asynchronous predicate, or a default value if no such element exists.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="predicate"/> is null.</exception>
         /// <exception cref="InvalidOperationException">(Asynchronous) More than one element satisfies the condition in the predicate.</exception>
-        public static ValueTask<TSource> SingleOrDefaultAwaitAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitAsyncCore<TSource>(source, predicate, cancellationToken);
+        public static ValueTask<TSource?> SingleOrDefaultAwaitAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitAsyncCore<TSource>(source, predicate, cancellationToken);
 
         /// <summary>
         /// Bypasses elements in an async-enumerable sequence as long as a condition is true, and then returns the remaining elements.
@@ -1429,7 +1429,7 @@ namespace System.Linq
         public static IAsyncEnumerable<TResult> SelectManyAwaitWithCancellation<TSource, TCollection, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector) => SelectManyAwaitWithCancellationCore<TSource, TCollection, TResult>(source, collectionSelector, resultSelector);
         public static IAsyncEnumerable<TResult> SelectManyAwaitWithCancellation<TSource, TCollection, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector) => SelectManyAwaitWithCancellationCore<TSource, TCollection, TResult>(source, collectionSelector, resultSelector);
         public static ValueTask<TSource> SingleAwaitWithCancellationAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleAwaitWithCancellationAsyncCore<TSource>(source, predicate, cancellationToken);
-        public static ValueTask<TSource> SingleOrDefaultAwaitWithCancellationAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitWithCancellationAsyncCore<TSource>(source, predicate, cancellationToken);
+        public static ValueTask<TSource?> SingleOrDefaultAwaitWithCancellationAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default) => SingleOrDefaultAwaitWithCancellationAsyncCore<TSource>(source, predicate, cancellationToken);
         public static IAsyncEnumerable<TSource> SkipWhileAwaitWithCancellation<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate) => SkipWhileAwaitWithCancellationCore<TSource>(source, predicate);
         public static IAsyncEnumerable<TSource> SkipWhileAwaitWithCancellation<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate) => SkipWhileAwaitWithCancellationCore<TSource>(source, predicate);
         public static ValueTask<int?> SumAwaitWithCancellationAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<int?>> selector, CancellationToken cancellationToken = default) => SumAwaitWithCancellationAsyncCore<TSource>(source, selector, cancellationToken);

Ix.NET/Source/System.Linq.Async/System/Linq/Operators/SingleOrDefault.cs

@@ -19,20 +19,20 @@ namespace System.Linq
         /// <returns>Sequence containing the single element in the async-enumerable sequence, or a default value if no such element exists.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="source"/> is null.</exception>
         /// <exception cref="InvalidOperationException">(Asynchronous) The source sequence contains more than one element.</exception>
-        public static ValueTask<TSource> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, CancellationToken cancellationToken = default)
+        public static ValueTask<TSource?> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
 
             return Core(source, cancellationToken);
 
-            static async ValueTask<TSource> Core(IAsyncEnumerable<TSource> source, CancellationToken cancellationToken)
+            static async ValueTask<TSource?> Core(IAsyncEnumerable<TSource> source, CancellationToken cancellationToken)
             {
                 if (source is IList<TSource> list)
                 {
                     return list.Count switch
                     {
-                        0 => default!,
+                        0 => default,
                         1 => list[0],
                         _ => throw Error.MoreThanOneElement(),
                     };
@@ -42,7 +42,7 @@ namespace System.Linq
                 {
                     if (!await e.MoveNextAsync())
                     {
-                        return default!;
+                        return default;
                     }
 
                     var result = e.Current;
@@ -67,7 +67,7 @@ namespace System.Linq
         /// <returns>Sequence containing the single element in the async-enumerable sequence that satisfies the condition in the predicate, or a default value if no such element exists.</returns>
         /// <exception cref="ArgumentNullException"><paramref name="source"/> or <paramref name="predicate"/> is null.</exception>
         /// <exception cref="InvalidOperationException">(Asynchronous) The sequence contains more than one element that satisfies the condition in the predicate.</exception>
-        public static ValueTask<TSource> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, CancellationToken cancellationToken = default)
+        public static ValueTask<TSource?> SingleOrDefaultAsync<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
@@ -76,7 +76,7 @@ namespace System.Linq
 
             return Core(source, predicate, cancellationToken);
 
-            static async ValueTask<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, CancellationToken cancellationToken)
+            static async ValueTask<TSource?> Core(IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, CancellationToken cancellationToken)
             {
                 await using (var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false))
                 {
@@ -99,11 +99,11 @@ namespace System.Linq
                     }
                 }
 
-                return default!;
+                return default;
             }
         }
 
-        internal static ValueTask<TSource> SingleOrDefaultAwaitAsyncCore<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default)
+        internal static ValueTask<TSource?> SingleOrDefaultAwaitAsyncCore<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
@@ -112,7 +112,7 @@ namespace System.Linq
 
             return Core(source, predicate, cancellationToken);
 
-            static async ValueTask<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken)
+            static async ValueTask<TSource?> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, CancellationToken cancellationToken)
             {
                 await using (var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false))
                 {
@@ -135,12 +135,12 @@ namespace System.Linq
                     }
                 }
 
-                return default!;
+                return default;
             }
         }
 
 #if !NO_DEEP_CANCELLATION
-        internal static ValueTask<TSource> SingleOrDefaultAwaitWithCancellationAsyncCore<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default)
+        internal static ValueTask<TSource?> SingleOrDefaultAwaitWithCancellationAsyncCore<TSource>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken = default)
         {
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
@@ -149,7 +149,7 @@ namespace System.Linq
 
             return Core(source, predicate, cancellationToken);
 
-            static async ValueTask<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken)
+            static async ValueTask<TSource?> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, CancellationToken cancellationToken)
             {
                 await using (var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false))
                 {
@@ -172,7 +172,7 @@ namespace System.Linq
                     }
                 }
 
-                return default!;
+                return default;
             }
         }
 #endif