From 86767a7021a7098f4d867377ba7d28f1298a5037 Mon Sep 17 00:00:00 2001
From: Stephen Toub <stoub@microsoft.com>
Date: Wed, 5 Dec 2018 21:47:34 -0500
Subject: [PATCH] Add CancellationToken parameter to GetAsyncEnumerator

---
 .../shared/System/Collections/Generic/IAsyncEnumerable.cs    | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/System.Private.CoreLib/shared/System/Collections/Generic/IAsyncEnumerable.cs b/src/System.Private.CoreLib/shared/System/Collections/Generic/IAsyncEnumerable.cs
index ef0207015142..302b96485506 100644
--- a/src/System.Private.CoreLib/shared/System/Collections/Generic/IAsyncEnumerable.cs
+++ b/src/System.Private.CoreLib/shared/System/Collections/Generic/IAsyncEnumerable.cs
@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+using System.Threading;
+
 namespace System.Collections.Generic
 {
     /// <summary>Exposes an enumerator that provides asynchronous iteration over values of a specified type.</summary>
@@ -9,7 +11,8 @@ namespace System.Collections.Generic
     public interface IAsyncEnumerable<out T>
     {
         /// <summary>Returns an enumerator that iterates asynchronously through the collection.</summary>
+        /// <param name="cancellationToken">A <see cref="CancellationToken"/> that may be used to cancel the asynchronous iteration.</param>
         /// <returns>An enumerator that can be used to iterate asynchronously through the collection.</returns>
-        IAsyncEnumerator<T> GetAsyncEnumerator();
+        IAsyncEnumerator<T> GetAsyncEnumerator(CancellationToken cancellationToken = default);
     }
 }