add TaskCompletionSource SetCanceled with CancellationToken (#202)

Author: SimonCropp

apiCount.include.md

@@ -1 +1 @@
-**API count: 326**
+**API count: 327**

api_list.include.md

@@ -330,6 +330,11 @@
  * `Task<TResult> WaitAsync<TResult>(TimeSpan, CancellationToken)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task-1.waitasync#system-threading-tasks-task-1-waitasync(system-timespan-system-threading-cancellationtoken))
 
 
+#### TaskCompletionSource<T>
+
+ * `void SetCanceled<T>(CancellationToken)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.taskcompletionsource-1.setcanceled#system-threading-tasks-taskcompletionsource-1-setcanceled(system-threading-cancellationtoken))
+
+
 #### TextReader
 
  * `ValueTask<Int32> ReadAsync(Memory<Char>, CancellationToken)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.io.textreader.readasync#system-io-textreader-readasync(system-memory((system-char))-system-threading-cancellationtoken))

readme.md

@@ -12,7 +12,7 @@ The package targets `netstandard2.0` and is designed to support the following ru
  * `net5.0`, `net6.0`, `net7.0`, `net8.0`, `net9.0`
 
 
-**API count: 326**<!-- singleLineInclude: apiCount. path: /apiCount.include.md -->
+**API count: 327**<!-- singleLineInclude: apiCount. path: /apiCount.include.md -->
 
 
 **See [Milestones](../../milestones?state=closed) for release notes.**
@@ -739,6 +739,11 @@ The class `Polyfill` includes the following extension methods:
  * `Task<TResult> WaitAsync<TResult>(TimeSpan, CancellationToken)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.task-1.waitasync#system-threading-tasks-task-1-waitasync(system-timespan-system-threading-cancellationtoken))
 
 
+#### TaskCompletionSource<T>
+
+ * `void SetCanceled<T>(CancellationToken)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.taskcompletionsource-1.setcanceled#system-threading-tasks-taskcompletionsource-1-setcanceled(system-threading-cancellationtoken))
+
+
 #### TextReader
 
  * `ValueTask<Int32> ReadAsync(Memory<Char>, CancellationToken)` [reference](https://learn.microsoft.com/en-us/dotnet/api/system.io.textreader.readasync#system-io-textreader-readasync(system-memory((system-char))-system-threading-cancellationtoken))

src/Consume/Consume.cs

@@ -276,6 +276,13 @@ void CancellationTokenUnsafeRegister()
         }, null);
     }
 
+    void TaskCompletionSource_SetCanceled_WithCancellationToken()
+    {
+        var completionSource = new TaskCompletionSource<int>();
+        var tokenSource = new CancellationTokenSource();
+        completionSource.SetCanceled(tokenSource.Token);
+    }
+
     async Task ProcessWaitForExitAsync()
     {
         var process = new Process();

src/Polyfill/Polyfill_TaskCompletionSource.cs

@@ -0,0 +1,37 @@
+// <auto-generated />
+#pragma warning disable
+
+#if !NET5_0_OR_GREATER
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Link = System.ComponentModel.DescriptionAttribute;
+
+static partial class Polyfill
+{
+    /// <summary>
+    /// Transitions the underlying <see cref="Task{TResult}"/> into the <see cref="TaskStatus.Canceled"/> state
+    /// using the specified token.
+    /// </summary>
+    /// <param name="cancellationToken">The cancellation token with which to cancel the <see cref="Task{TResult}"/>.</param>
+    /// <exception cref="InvalidOperationException">
+    /// The underlying <see cref="Task{TResult}"/> is already in one of the three final states:
+    /// <see cref="TaskStatus.RanToCompletion"/>,
+    /// <see cref="TaskStatus.Faulted"/>, or
+    /// <see cref="TaskStatus.Canceled"/>.
+    /// </exception>
+    [Link("https://learn.microsoft.com/en-us/dotnet/api/system.threading.tasks.taskcompletionsource-1.setcanceled#system-threading-tasks-taskcompletionsource-1-setcanceled(system-threading-cancellationtoken)")]
+    public static void SetCanceled<T>(
+        this TaskCompletionSource<T> target,
+        CancellationToken cancellationToken)
+    {
+        if (target.TrySetCanceled(cancellationToken))
+        {
+            return;
+        }
+
+        throw new InvalidOperationException("An attempt was made to transition a task to a final state when it had already completed.");
+    }
+}
+#endif

src/Tests/PolyfillTests_TaskCompletionSource.cs

@@ -0,0 +1,28 @@
+#pragma warning disable CS4014
+partial class PolyfillTests
+{
+    [Test]
+    public async Task TaskCompletionSource_SetCanceled_WithCancellationToken()
+    {
+        var completionSource = new TaskCompletionSource<int>();
+        var tokenSource = new CancellationTokenSource();
+
+        // Simulate some background work that will cancel the task
+        Task.Run(async () =>
+        {
+            await Task.Delay(20); // Simulate a delay
+            completionSource.SetCanceled(tokenSource.Token);
+        });
+
+        try
+        {
+            // Await the task
+            var result = await completionSource.Task;
+            Console.WriteLine($"Task completed with result: {result}");
+        }
+        catch (TaskCanceledException)
+        {
+            Console.WriteLine("Task was canceled.");
+        }
+    }
+}