// CS1678: Parameter `1' is declared as type `T' but should be `IStream<T>' // Line: 14 using System; interface IStream<T> { } static class X { public static IStream<U> Select<T, U> (IStream<T> stream, Func<IStream<T>, U> selector) { return Select<T, U> (stream, (T _) => selector(stream)); } }