Code inspection: Async-iterator has one or more parameters of type 'CancellationToken' but none of them is annotated with the 'EnumeratorCancellation' attribute.

This inspection reports an async iterator method that has a CancellationToken parameter but does not mark any such parameter with [EnumeratorCancellation]. Without that attribute, the cancellation token passed by await foreach through GetAsyncEnumerator(...) is not forwarded to the iterator parameter you probably intended to use.

Example

                using System.Collections.Generic;
                using System.Threading;
                class C
                {
                    public async IAsyncEnumerable<int> M(CancellationToken token)
                    {
                        yield return 0;
                    }
                }
            

                using System.Collections.Generic;
                using System.Runtime.CompilerServices;
                using System.Threading;
                class C
                {
                    public async IAsyncEnumerable<int> M([EnumeratorCancellation] CancellationToken token)
                    {
                        yield return 0;
                    }
                }
            

Quick-fix

The quick-fix adds the [EnumeratorCancellation] attribute to the chosen CancellationToken parameter.

21 April 2026