Remove ASYNC_ITERATOR_CAN_RETURN_AETOR; this is now supported in the latest preview.

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

@@ -20,7 +20,7 @@ namespace System.Linq
             if (second == null)
                 throw Error.ArgumentNull(nameof(second));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -45,7 +45,7 @@ namespace System.Linq
 #endif
         }
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class ExceptAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly IEqualityComparer<TSource> _comparer;

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

@@ -26,7 +26,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -68,7 +68,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -111,7 +111,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -138,7 +138,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class GroupJoinAsyncEnumerable<TOuter, TInner, TKey, TResult> : IAsyncEnumerable<TResult>
         {
             private readonly IEqualityComparer<TKey> _comparer;

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

@@ -20,7 +20,7 @@ namespace System.Linq
             if (second == null)
                 throw Error.ArgumentNull(nameof(second));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -45,7 +45,7 @@ namespace System.Linq
 #endif
         }
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class IntersectAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly IEqualityComparer<TSource> _comparer;

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

@@ -27,7 +27,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -85,7 +85,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -144,7 +144,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -187,7 +187,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class JoinAsyncIterator<TOuter, TInner, TKey, TResult> : AsyncIterator<TResult>
         {
             private readonly IAsyncEnumerable<TOuter> _outer;

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

@@ -36,7 +36,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -103,7 +103,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -133,7 +133,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -217,7 +217,7 @@ namespace System.Linq
             }
         }
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class SelectEnumerableWithIndexAsyncIterator<TSource, TResult> : AsyncIterator<TResult>
         {
             private readonly Func<TSource, int, TResult> _selector;
@@ -523,7 +523,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class SelectEnumerableWithIndexAsyncIteratorWithTask<TSource, TResult> : AsyncIterator<TResult>
         {
             private readonly Func<TSource, int, ValueTask<TResult>> _selector;

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

@@ -50,7 +50,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -84,7 +84,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -119,7 +119,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -156,7 +156,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -185,7 +185,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -215,7 +215,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -245,7 +245,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -281,7 +281,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -318,7 +318,7 @@ namespace System.Linq
             if (resultSelector == null)
                 throw Error.ArgumentNull(nameof(resultSelector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -884,7 +884,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class SelectManyAsyncIterator<TSource, TCollection, TResult> : AsyncIterator<TResult>
         {
             private const int State_Source = 1;

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

@@ -27,7 +27,7 @@ namespace System.Linq
                 count = 0;
             }
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -60,7 +60,7 @@ namespace System.Linq
 #endif
         }
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class SkipLastAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly int _count;

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

@@ -18,7 +18,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -55,7 +55,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -99,7 +99,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -137,7 +137,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -175,7 +175,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -220,7 +220,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -258,7 +258,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class SkipWhileAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly Func<TSource, bool> _predicate;

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

@@ -20,7 +20,7 @@ namespace System.Linq
                 return Empty<TSource>();
             }
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -68,7 +68,7 @@ namespace System.Linq
 #endif
         }
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class TakeLastAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly int _count;

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

@@ -18,7 +18,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -45,7 +45,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -79,7 +79,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -107,7 +107,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -135,7 +135,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -170,7 +170,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -198,7 +198,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class TakeWhileAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly Func<TSource, bool> _predicate;

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

@@ -34,7 +34,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -100,7 +100,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -133,7 +133,7 @@ namespace System.Linq
             if (predicate == null)
                 throw Error.ArgumentNull(nameof(predicate));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TSource> Core(CancellationToken cancellationToken)
@@ -228,7 +228,7 @@ namespace System.Linq
             }
         }
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class WhereEnumerableWithIndexAsyncIterator<TSource> : AsyncIterator<TSource>
         {
             private readonly Func<TSource, int, bool> _predicate;
@@ -428,7 +428,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class WhereEnumerableWithIndexAsyncIteratorWithTask<TSource> : AsyncIterator<TSource>
         {
             private readonly Func<TSource, int, ValueTask<bool>> _predicate;

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

@@ -20,7 +20,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -50,7 +50,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -81,7 +81,7 @@ namespace System.Linq
             if (selector == null)
                 throw Error.ArgumentNull(nameof(selector));
 
-#if CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR // https://github.com/dotnet/roslyn/pull/31114
+#if CSHARP8 && USE_ASYNC_ITERATOR
             return Create(Core);
 
             async IAsyncEnumerator<TResult> Core(CancellationToken cancellationToken)
@@ -103,7 +103,7 @@ namespace System.Linq
         }
 #endif
 
-#if !(CSHARP8 && USE_ASYNC_ITERATOR && ASYNC_ITERATOR_CAN_RETURN_AETOR)
+#if !(CSHARP8 && USE_ASYNC_ITERATOR)
         private sealed class ZipAsyncIterator<TFirst, TSecond, TResult> : AsyncIterator<TResult>
         {
             private readonly IAsyncEnumerable<TFirst> _first;