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Fix Task.WhenAny failure mode when passed ICollection of zero tasks #55580

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Merged
merged 1 commit into from
Jul 14, 2021
Merged

Fix Task.WhenAny failure mode when passed ICollection of zero tasks #55580

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8 changes: 7 additions & 1 deletion src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6305,8 +6305,14 @@ public static Task<Task> WhenAny(IEnumerable<Task> tasks)
return WhenAny(taskArray);
}

int count = taskCollection.Count;
if (count <= 0)
{
ThrowHelper.ThrowArgumentException(ExceptionResource.Task_MultiTaskContinuation_EmptyTaskList, ExceptionArgument.tasks);
}

int index = 0;
taskArray = new Task[taskCollection.Count];
taskArray = new Task[count];
foreach (Task task in tasks)
{
if (task == null) ThrowHelper.ThrowArgumentException(ExceptionResource.Task_MultiTaskContinuation_NullTask, ExceptionArgument.tasks);
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14 changes: 14 additions & 0 deletions src/libraries/System.Threading.Tasks/tests/MethodCoverage.cs
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Expand Up @@ -188,6 +188,20 @@ public static void Task_WhenAny_TwoTasks_InvalidArgs_Throws()
AssertExtensions.Throws<ArgumentNullException>("task2", () => Task.WhenAny(Task.FromResult(2), null));
}

[Fact]
public static void Task_WhenAny_NoTasks_Throws()
{
AssertExtensions.Throws<ArgumentException>("tasks", () => { Task.WhenAny(new Task[0]); });
AssertExtensions.Throws<ArgumentException>("tasks", () => { Task.WhenAny(new List<Task>()); });
AssertExtensions.Throws<ArgumentException>("tasks", () => { Task.WhenAny(EmptyIterator<Task>()); });

AssertExtensions.Throws<ArgumentException>("tasks", () => { Task.WhenAny(new Task<int>[0]); });
AssertExtensions.Throws<ArgumentException>("tasks", () => { Task.WhenAny(new List<Task<int>>()); });
AssertExtensions.Throws<ArgumentException>("tasks", () => { Task.WhenAny(EmptyIterator<Task<int>>()); });

static IEnumerable<T> EmptyIterator<T>() { yield break; }
}

[Fact]
public static async Task Task_WhenAny_TwoTasks_OnePreCompleted()
{
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