HLQ009: Consider removing an empty optional enumerator method.

Cause

A method is empty and is only required when an enumerator interface is implemented.

Severity

Info

Rule description

The methods Reset, Dispose and DisposeAsync are not required for an enumerator to be accepted by foreach. These are only required when the enumerator implements IEnumerator, IEnumerator<> or IAsyncEnumerator<>.

How to fix violations

If the method is empty and none of the mentioned interfaces is implemented then consider removing it.

When to suppress warnings

When method is part of some other contract.

Example of a violation

readonly struct Enumerable<T>
{
    public Enumerator GetEnumerator() => new Enumerator();

    public struct Enumerator // no enumerator interfaces implemented
    {
        public T Current => default;

        public bool MoveNext() => false;

        // empty Reset method
        public void Reset() => throw new NotImplementedException();

        // empty Dispose method
        public void Dispose() { }
    }
}

Example of how to fix

readonly struct Enumerable<T>
{
    public Enumerator GetEnumerator() => new Enumerator();

    public struct Enumerator
    {
        public T Current => default;

        public bool MoveNext() => false;
    }
}