Enable usage of EnumeratorCancellaton across the board.

Ix.NET/Source/Directory.build.targets

@@ -21,15 +21,9 @@
   <PropertyGroup Condition="'$(TargetFramework)' == 'net45'">
     <DefineConstants>$(DefineConstants);NO_ARRAY_EMPTY;NO_TASK_FROMEXCEPTION</DefineConstants>
   </PropertyGroup>
-  <PropertyGroup Condition="'$(TargetFramework)' == 'net46' or '$(TargetFramework)' == 'net461'">
-    <DefineConstants>$(DefineConstants)</DefineConstants>
-  </PropertyGroup>
   <PropertyGroup Condition="'$(TargetFramework)' == 'netcoreapp3.0' or '$(TargetFramework)' == 'netstandard2.1' or '$(TargetFramework)' == 'netstandard2.0'">
     <DefineConstants>$(DefineConstants);HAS_VALUETUPLE</DefineConstants>
   </PropertyGroup>
-  <PropertyGroup Condition="'$(TargetFramework)' == 'netcoreapp3.0' or '$(TargetFramework)' == 'netstandard2.1'">
-    <DefineConstants>$(DefineConstants);HAS_ASYNC_ENUMERABLE_CANCELLATION</DefineConstants>
-  </PropertyGroup>
 
   <PropertyGroup>
     <Product>$(AssemblyName) ($(TargetFramework))</Product>

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Amb.cs

@@ -25,15 +25,9 @@ namespace System.Linq
             if (second == null)
                 throw Error.ArgumentNull(nameof(second));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 IAsyncEnumerator<TSource>? firstEnumerator = null;
                 IAsyncEnumerator<TSource>? secondEnumerator = null;
@@ -120,7 +114,7 @@ namespace System.Linq
                 }
 
                 try
-                {                    
+                {
                     await using (winner.ConfigureAwait(false))
                     {
                         if (!await moveNextWinner.ConfigureAwait(false))

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Buffer.cs

@@ -26,15 +26,9 @@ namespace System.Linq
             if (count <= 0)
                 throw Error.ArgumentOutOfRange(nameof(count));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, count);
 
-            static async IAsyncEnumerable<IList<TSource>> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<IList<TSource>> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<IList<TSource>> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var buffer = new List<TSource>(count);
 
@@ -76,15 +70,9 @@ namespace System.Linq
             if (skip <= 0)
                 throw Error.ArgumentOutOfRange(nameof(skip));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, count, skip);
 
-            static async IAsyncEnumerable<IList<TSource>> Core(IAsyncEnumerable<TSource> source, int count, int skip, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<IList<TSource>> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<IList<TSource>> Core(IAsyncEnumerable<TSource> source, int count, int skip, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var buffers = new Queue<IList<TSource>>();
 

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Catch.cs

@@ -33,15 +33,9 @@ namespace System.Linq
             if (handler == null)
                 throw Error.ArgumentNull(nameof(handler));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, handler);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TException, IAsyncEnumerable<TSource>> handler, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TException, IAsyncEnumerable<TSource>> handler, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 // REVIEW: This implementation mirrors the Ix implementation, which does not protect GetEnumerator
                 //         using the try statement either. A more trivial implementation would use await foreach
@@ -102,15 +96,9 @@ namespace System.Linq
             if (handler == null)
                 throw Error.ArgumentNull(nameof(handler));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, handler);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TException, ValueTask<IAsyncEnumerable<TSource>>> handler, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TException, ValueTask<IAsyncEnumerable<TSource>>> handler, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 // REVIEW: This implementation mirrors the Ix implementation, which does not protect GetEnumerator
                 //         using the try statement either. A more trivial implementation would use await foreach
@@ -172,15 +160,9 @@ namespace System.Linq
             if (handler == null)
                 throw Error.ArgumentNull(nameof(handler));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, handler);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TException, CancellationToken, ValueTask<IAsyncEnumerable<TSource>>> handler, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TException, CancellationToken, ValueTask<IAsyncEnumerable<TSource>>> handler, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 // REVIEW: This implementation mirrors the Ix implementation, which does not protect GetEnumerator
                 //         using the try statement either. A more trivial implementation would use await foreach

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Concat.cs

@@ -22,15 +22,9 @@ namespace System.Linq
             if (sources == null)
                 throw Error.ArgumentNull(nameof(sources));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(sources);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<IAsyncEnumerable<TSource>> sources, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<IAsyncEnumerable<TSource>> sources, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var source in sources.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -54,15 +48,9 @@ namespace System.Linq
             if (sources == null)
                 throw Error.ArgumentNull(nameof(sources));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(sources);
 
-            static async IAsyncEnumerable<TSource> Core(IEnumerable<IAsyncEnumerable<TSource>> sources, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IEnumerable<IAsyncEnumerable<TSource>> sources, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 foreach (var source in sources)
                 {
@@ -86,15 +74,9 @@ namespace System.Linq
             if (sources == null)
                 throw Error.ArgumentNull(nameof(sources));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(sources);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource>[] sources, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource>[] sources, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 foreach (var source in sources)
                 {

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Defer.cs

@@ -22,15 +22,9 @@ namespace System.Linq
             if (factory == null)
                 throw Error.ArgumentNull(nameof(factory));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(factory);
 
-            static async IAsyncEnumerable<TSource> Core(Func<IAsyncEnumerable<TSource>> factory, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(Func<IAsyncEnumerable<TSource>> factory, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var item in factory().WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -52,15 +46,9 @@ namespace System.Linq
             if (factory == null)
                 throw Error.ArgumentNull(nameof(factory));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(factory);
 
-            static async IAsyncEnumerable<TSource> Core(Func<Task<IAsyncEnumerable<TSource>>> factory, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(Func<Task<IAsyncEnumerable<TSource>>> factory, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var item in (await factory().ConfigureAwait(false)).WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -85,15 +73,9 @@ namespace System.Linq
             if (factory == null)
                 throw Error.ArgumentNull(nameof(factory));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(factory);
 
-            static async IAsyncEnumerable<TSource> Core(Func<CancellationToken, Task<IAsyncEnumerable<TSource>>> factory, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(Func<CancellationToken, Task<IAsyncEnumerable<TSource>>> factory, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var item in (await factory(cancellationToken).ConfigureAwait(false)).WithCancellation(cancellationToken).ConfigureAwait(false))
                 {

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/DistinctUntilChanged.cs

@@ -166,15 +166,9 @@ namespace System.Linq
         {
             comparer ??= EqualityComparer<TSource>.Default;
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, comparer);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, IEqualityComparer<TSource> comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, IEqualityComparer<TSource> comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -207,15 +201,9 @@ namespace System.Linq
         {
             comparer ??= EqualityComparer<TKey>.Default;
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, keySelector, comparer);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -252,15 +240,9 @@ namespace System.Linq
         {
             comparer ??= EqualityComparer<TKey>.Default;
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, keySelector, comparer);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -298,15 +280,9 @@ namespace System.Linq
         {
             comparer ??= EqualityComparer<TKey>.Default;
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, keySelector, comparer);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Do.cs

@@ -297,151 +297,115 @@ namespace System.Linq
             return DoCore(source, new Action<TSource>(observer.OnNext), new Action<Exception>(observer.OnError), new Action(observer.OnCompleted));
         }
 
-        private static IAsyncEnumerable<TSource> DoCore<TSource>(IAsyncEnumerable<TSource> source, Action<TSource> onNext, Action<Exception>? onError, Action? onCompleted)
+        private static async IAsyncEnumerable<TSource> DoCore<TSource>(IAsyncEnumerable<TSource> source, Action<TSource> onNext, Action<Exception>? onError, Action? onCompleted, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
-            return Core(source, onNext, onError, onCompleted);
+            await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
-            // TODO: Can remove local function.
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Action<TSource> onNext, Action<Exception>? onError, Action? onCompleted, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            while (true)
             {
-                await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
+                TSource item;
 
-                while (true)
+                try
                 {
-                    TSource item;
-
-                    try
-                    {
-                        if (!await e.MoveNextAsync())
-                        {
-                            break;
-                        }
-
-                        item = e.Current;
-
-                        onNext(item);
-                    }
-                    catch (OperationCanceledException)
+                    if (!await e.MoveNextAsync())
                     {
-                        throw;
-                    }
-                    catch (Exception ex) when (onError != null)
-                    {
-                        onError(ex);
-                        throw;
+                        break;
                     }
 
-                    yield return item;
+                    item = e.Current;
+
+                    onNext(item);
+                }
+                catch (OperationCanceledException)
+                {
+                    throw;
+                }
+                catch (Exception ex) when (onError != null)
+                {
+                    onError(ex);
+                    throw;
                 }
 
-                onCompleted?.Invoke();
+                yield return item;
             }
+
+            onCompleted?.Invoke();
         }
 
-        private static IAsyncEnumerable<TSource> DoCore<TSource>(IAsyncEnumerable<TSource> source, Func<TSource, Task> onNext, Func<Exception, Task>? onError, Func<Task>? onCompleted)
+        private static async IAsyncEnumerable<TSource> DoCore<TSource>(IAsyncEnumerable<TSource> source, Func<TSource, Task> onNext, Func<Exception, Task>? onError, Func<Task>? onCompleted, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
-            return Core(source, onNext, onError, onCompleted);
-
-            // TODO: Can remove local function.
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, Task> onNext, Func<Exception, Task>? onError, Func<Task>? onCompleted, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
+            await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            while (true)
             {
-                await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
+                TSource item;
 
-                while (true)
+                try
                 {
-                    TSource item;
-
-                    try
-                    {
-                        if (!await e.MoveNextAsync())
-                        {
-                            break;
-                        }
-
-                        item = e.Current;
-
-                        await onNext(item).ConfigureAwait(false);
-                    }
-                    catch (OperationCanceledException)
+                    if (!await e.MoveNextAsync())
                     {
-                        throw;
-                    }
-                    catch (Exception ex) when (onError != null)
-                    {
-                        await onError(ex).ConfigureAwait(false);
-                        throw;
+                        break;
                     }
 
-                    yield return item;
-                }
+                    item = e.Current;
 
-                if (onCompleted != null)
+                    await onNext(item).ConfigureAwait(false);
+                }
+                catch (OperationCanceledException)
+                {
+                    throw;
+                }
+                catch (Exception ex) when (onError != null)
                 {
-                    await onCompleted().ConfigureAwait(false);
+                    await onError(ex).ConfigureAwait(false);
+                    throw;
                 }
+
+                yield return item;
+            }
+
+            if (onCompleted != null)
+            {
+                await onCompleted().ConfigureAwait(false);
             }
         }
 
 #if !NO_DEEP_CANCELLATION
-        private static IAsyncEnumerable<TSource> DoCore<TSource>(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, Task> onNext, Func<Exception, CancellationToken, Task>? onError, Func<CancellationToken, Task>? onCompleted)
+        private static async IAsyncEnumerable<TSource> DoCore<TSource>(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, Task> onNext, Func<Exception, CancellationToken, Task>? onError, Func<CancellationToken, Task>? onCompleted, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
-            return Core(source, onNext, onError, onCompleted);
-
-            // TODO: Can remove local function.
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, Task> onNext, Func<Exception, CancellationToken, Task>? onError, Func<CancellationToken, Task>? onCompleted, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
+            await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            while (true)
             {
-                await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
+                TSource item;
 
-                while (true)
+                try
                 {
-                    TSource item;
-
-                    try
-                    {
-                        if (!await e.MoveNextAsync())
-                        {
-                            break;
-                        }
-
-                        item = e.Current;
-
-                        await onNext(item, cancellationToken).ConfigureAwait(false);
-                    }
-                    catch (OperationCanceledException)
-                    {
-                        throw;
-                    }
-                    catch (Exception ex) when (onError != null)
+                    if (!await e.MoveNextAsync())
                     {
-                        await onError(ex, cancellationToken).ConfigureAwait(false);
-                        throw;
+                        break;
                     }
 
-                    yield return item;
-                }
+                    item = e.Current;
 
-                if (onCompleted != null)
+                    await onNext(item, cancellationToken).ConfigureAwait(false);
+                }
+                catch (OperationCanceledException)
                 {
-                    await onCompleted(cancellationToken).ConfigureAwait(false);
+                    throw;
                 }
+                catch (Exception ex) when (onError != null)
+                {
+                    await onError(ex, cancellationToken).ConfigureAwait(false);
+                    throw;
+                }
+
+                yield return item;
+            }
+
+            if (onCompleted != null)
+            {
+                await onCompleted(cancellationToken).ConfigureAwait(false);
             }
         }
 #endif

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Expand.cs

@@ -24,15 +24,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, IAsyncEnumerable<TSource>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, IAsyncEnumerable<TSource>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var queue = new Queue<IAsyncEnumerable<TSource>>();
 
@@ -64,15 +58,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<IAsyncEnumerable<TSource>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<IAsyncEnumerable<TSource>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var queue = new Queue<IAsyncEnumerable<TSource>>();
 
@@ -105,15 +93,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<IAsyncEnumerable<TSource>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<IAsyncEnumerable<TSource>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var queue = new Queue<IAsyncEnumerable<TSource>>();
 

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Finally.cs

@@ -25,15 +25,9 @@ namespace System.Linq
             if (finallyAction == null)
                 throw Error.ArgumentNull(nameof(finallyAction));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, finallyAction);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Action finallyAction, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Action finallyAction, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 try
                 {
@@ -64,15 +58,9 @@ namespace System.Linq
             if (finallyAction == null)
                 throw Error.ArgumentNull(nameof(finallyAction));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, finallyAction);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<Task> finallyAction, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<Task> finallyAction, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 try
                 {

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Generate.cs

@@ -32,15 +32,9 @@ namespace System.Linq
                 throw Error.ArgumentNull(nameof(resultSelector));
 
 #pragma warning disable CS1998 // Async method lacks 'await' operators and will run synchronously
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(initialState, condition, iterate, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(TState initialState, Func<TState, bool> condition, Func<TState, TState> iterate, Func<TState, TResult> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(TState initialState, Func<TState, bool> condition, Func<TState, TState> iterate, Func<TState, TResult> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 for (var state = initialState; condition(state); state = iterate(state))
                 {

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/IgnoreElements.cs

@@ -22,15 +22,9 @@ namespace System.Linq
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var _ in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Merge.cs

@@ -22,15 +22,9 @@ namespace System.Linq
             if (sources == null)
                 throw Error.ArgumentNull(nameof(sources));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(sources);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource>[] sources, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource>[] sources, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
 #if USE_FAIR_AND_CHEAPER_MERGE
             //
             // This new implementation of Merge differs from the original one in a few ways:

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Repeat.cs

@@ -19,15 +19,9 @@ namespace System.Linq
         public static IAsyncEnumerable<TResult> Repeat<TResult>(TResult element)
         {
 #pragma warning disable CS1998 // Async method lacks 'await' operators and will run synchronously
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(element);
 
-            static async IAsyncEnumerable<TResult> Core(TResult element, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(TResult element, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 while (true)
                 {
@@ -51,15 +45,9 @@ namespace System.Linq
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 while (true)
                 {
@@ -87,15 +75,9 @@ namespace System.Linq
             if (count < 0)
                 throw Error.ArgumentOutOfRange(nameof(count));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, count);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 for (var i = 0; i < count; i++)
                 {

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Scan.cs

@@ -30,15 +30,9 @@ namespace System.Linq
             if (accumulator == null)
                 throw Error.ArgumentNull(nameof(accumulator));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, accumulator);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TSource, TSource> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TSource, TSource> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -76,15 +70,9 @@ namespace System.Linq
             if (accumulator == null)
                 throw Error.ArgumentNull(nameof(accumulator));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, seed, accumulator);
 
-            static async IAsyncEnumerable<TAccumulate> Core(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TAccumulate> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TAccumulate> Core(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, TAccumulate> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var res = seed;
 
@@ -113,15 +101,9 @@ namespace System.Linq
             if (accumulator == null)
                 throw Error.ArgumentNull(nameof(accumulator));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, accumulator);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TSource, ValueTask<TSource>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TSource, ValueTask<TSource>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -158,15 +140,9 @@ namespace System.Linq
             if (accumulator == null)
                 throw Error.ArgumentNull(nameof(accumulator));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, accumulator);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TSource, CancellationToken, ValueTask<TSource>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, TSource, CancellationToken, ValueTask<TSource>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -205,15 +181,9 @@ namespace System.Linq
             if (accumulator == null)
                 throw Error.ArgumentNull(nameof(accumulator));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, seed, accumulator);
 
-            static async IAsyncEnumerable<TAccumulate> Core(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, ValueTask<TAccumulate>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TAccumulate> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TAccumulate> Core(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, ValueTask<TAccumulate>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var res = seed;
 
@@ -245,15 +215,9 @@ namespace System.Linq
             if (accumulator == null)
                 throw Error.ArgumentNull(nameof(accumulator));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, seed, accumulator);
 
-            static async IAsyncEnumerable<TAccumulate> Core(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, CancellationToken, ValueTask<TAccumulate>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TAccumulate> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TAccumulate> Core(IAsyncEnumerable<TSource> source, TAccumulate seed, Func<TAccumulate, TSource, CancellationToken, ValueTask<TAccumulate>> accumulator, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var res = seed;
 

Ix.NET/Source/System.Interactive.Async/System/Linq/Operators/Using.cs

@@ -28,15 +28,9 @@ namespace System.Linq
             if (enumerableFactory == null)
                 throw Error.ArgumentNull(nameof(enumerableFactory));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(resourceFactory, enumerableFactory);
 
-            static async IAsyncEnumerable<TSource> Core(Func<TResource> resourceFactory, Func<TResource, IAsyncEnumerable<TSource>> enumerableFactory, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(Func<TResource> resourceFactory, Func<TResource, IAsyncEnumerable<TSource>> enumerableFactory, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 using var resource = resourceFactory();
 
@@ -65,15 +59,9 @@ namespace System.Linq
             if (enumerableFactory == null)
                 throw Error.ArgumentNull(nameof(enumerableFactory));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(resourceFactory, enumerableFactory);
 
-            static async IAsyncEnumerable<TSource> Core(Func<Task<TResource>> resourceFactory, Func<TResource, ValueTask<IAsyncEnumerable<TSource>>> enumerableFactory, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(Func<Task<TResource>> resourceFactory, Func<TResource, ValueTask<IAsyncEnumerable<TSource>>> enumerableFactory, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 using var resource = await resourceFactory().ConfigureAwait(false);
 
@@ -104,15 +92,9 @@ namespace System.Linq
             if (enumerableFactory == null)
                 throw Error.ArgumentNull(nameof(enumerableFactory));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(resourceFactory, enumerableFactory);
 
-            static async IAsyncEnumerable<TSource> Core(Func<CancellationToken, Task<TResource>> resourceFactory, Func<TResource, CancellationToken, ValueTask<IAsyncEnumerable<TSource>>> enumerableFactory, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return AsyncEnumerable.Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(Func<CancellationToken, Task<TResource>> resourceFactory, Func<TResource, CancellationToken, ValueTask<IAsyncEnumerable<TSource>>> enumerableFactory, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 using var resource = await resourceFactory(cancellationToken).ConfigureAwait(false);
 

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

@@ -30,15 +30,9 @@ namespace System.Linq
                 return typedSource;
             }
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<object> source, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<object> source, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var obj in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {

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

@@ -37,15 +37,9 @@ namespace System.Linq
             if (second == null)
                 throw Error.ArgumentNull(nameof(second));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second, comparer);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second, IEqualityComparer<TSource>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second, IEqualityComparer<TSource>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var set = new Set<TSource>(comparer);
 

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

@@ -55,15 +55,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, IAsyncEnumerable<TInner>, TResult> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, IAsyncEnumerable<TInner>, TResult> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = outer.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -98,15 +92,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, ValueTask<TKey>> outerKeySelector, Func<TInner, ValueTask<TKey>> innerKeySelector, Func<TOuter, IAsyncEnumerable<TInner>, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, ValueTask<TKey>> outerKeySelector, Func<TInner, ValueTask<TKey>> innerKeySelector, Func<TOuter, IAsyncEnumerable<TInner>, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = outer.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -142,15 +130,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, CancellationToken, ValueTask<TKey>> outerKeySelector, Func<TInner, CancellationToken, ValueTask<TKey>> innerKeySelector, Func<TOuter, IAsyncEnumerable<TInner>, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, CancellationToken, ValueTask<TKey>> outerKeySelector, Func<TInner, CancellationToken, ValueTask<TKey>> innerKeySelector, Func<TOuter, IAsyncEnumerable<TInner>, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = outer.GetConfiguredAsyncEnumerator(cancellationToken, false);
 

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

@@ -37,15 +37,9 @@ namespace System.Linq
             if (second == null)
                 throw Error.ArgumentNull(nameof(second));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second, comparer);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second, IEqualityComparer<TSource>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> first, IAsyncEnumerable<TSource> second, IEqualityComparer<TSource>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var set = new Set<TSource>(comparer);
 

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

@@ -55,15 +55,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, TKey> outerKeySelector, Func<TInner, TKey> innerKeySelector, Func<TOuter, TInner, TResult> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = outer.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -114,15 +108,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, ValueTask<TKey>> outerKeySelector, Func<TInner, ValueTask<TKey>> innerKeySelector, Func<TOuter, TInner, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, ValueTask<TKey>> outerKeySelector, Func<TInner, ValueTask<TKey>> innerKeySelector, Func<TOuter, TInner, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = outer.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -174,15 +162,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(outer, inner, outerKeySelector, innerKeySelector, resultSelector, comparer);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, CancellationToken, ValueTask<TKey>> outerKeySelector, Func<TInner, CancellationToken, ValueTask<TKey>> innerKeySelector, Func<TOuter, TInner, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TOuter> outer, IAsyncEnumerable<TInner> inner, Func<TOuter, CancellationToken, ValueTask<TKey>> outerKeySelector, Func<TInner, CancellationToken, ValueTask<TKey>> innerKeySelector, Func<TOuter, TInner, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey>? comparer, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = outer.GetConfiguredAsyncEnumerator(cancellationToken, false);
 

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

@@ -30,15 +30,9 @@ namespace System.Linq
             if (source == null)
                 throw Error.ArgumentNull(nameof(source));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<object> source, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<object> source, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var obj in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {

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

@@ -50,15 +50,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, TResult> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, TResult> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -113,15 +107,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -145,15 +133,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 

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

@@ -69,15 +69,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, IAsyncEnumerable<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, IAsyncEnumerable<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -105,15 +99,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<IAsyncEnumerable<TResult>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<IAsyncEnumerable<TResult>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -142,15 +130,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<IAsyncEnumerable<TResult>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<IAsyncEnumerable<TResult>>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -192,15 +174,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, collectionSelector, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, IAsyncEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, IAsyncEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -223,15 +199,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, collectionSelector, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -255,15 +225,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, collectionSelector, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -298,15 +262,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, collectionSelector, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, IAsyncEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, IAsyncEnumerable<TCollection>> collectionSelector, Func<TSource, TCollection, TResult> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -336,15 +294,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, collectionSelector, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -375,15 +327,9 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, collectionSelector, resultSelector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<IAsyncEnumerable<TCollection>>> collectionSelector, Func<TSource, TCollection, CancellationToken, ValueTask<TResult>> resultSelector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 

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

@@ -41,15 +41,9 @@ namespace System.Linq
                 count = 0;
             }
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, count);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var queue = new Queue<TSource>();
 

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

@@ -25,15 +25,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -72,15 +66,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 var index = -1;
@@ -116,15 +104,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -155,15 +137,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
 
@@ -194,15 +170,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 var index = -1;
@@ -239,15 +209,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e = source.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 var index = -1;

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

@@ -34,15 +34,9 @@ namespace System.Linq
                 return Empty<TSource>();
             }
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, count);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, int count, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 Queue<TSource> queue;
 

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

@@ -25,15 +25,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -63,15 +57,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -99,15 +87,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -129,15 +111,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await foreach (var element in source.WithCancellation(cancellationToken).ConfigureAwait(false))
                 {
@@ -159,15 +135,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -196,15 +166,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 

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

@@ -49,15 +49,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, bool> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -117,15 +111,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 
@@ -152,15 +140,9 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(source, predicate);
 
-            async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TSource> Core(IAsyncEnumerable<TSource> source, Func<TSource, int, CancellationToken, ValueTask<bool>> predicate, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 var index = -1;
 

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

@@ -18,15 +18,9 @@ namespace System.Linq
             if (second == null)
                 throw Error.ArgumentNull(nameof(second));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second);
 
             static async IAsyncEnumerable<(TFirst, TSecond)> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<(TFirst, TSecond)> Core(CancellationToken cancellationToken)
-#endif
             {
                 await using var e1 = first.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 await using var e2 = second.GetConfiguredAsyncEnumerator(cancellationToken, false);
@@ -59,15 +53,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, Func<TFirst, TSecond, TResult> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, Func<TFirst, TSecond, TResult> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e1 = first.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 await using var e2 = second.GetConfiguredAsyncEnumerator(cancellationToken, false);
@@ -88,15 +76,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, Func<TFirst, TSecond, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, Func<TFirst, TSecond, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e1 = first.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 await using var e2 = second.GetConfiguredAsyncEnumerator(cancellationToken, false);
@@ -118,15 +100,9 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if HAS_ASYNC_ENUMERABLE_CANCELLATION
             return Core(first, second, selector);
 
-            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, Func<TFirst, TSecond, CancellationToken, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation]CancellationToken cancellationToken = default)
-#else
-            return Create(Core);
-
-            async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
-#endif
+            static async IAsyncEnumerable<TResult> Core(IAsyncEnumerable<TFirst> first, IAsyncEnumerable<TSecond> second, Func<TFirst, TSecond, CancellationToken, ValueTask<TResult>> selector, [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken = default)
             {
                 await using var e1 = first.GetConfiguredAsyncEnumerator(cancellationToken, false);
                 await using var e2 = second.GetConfiguredAsyncEnumerator(cancellationToken, false);