// CS0278: `IListCounter' contains ambiguous implementation of `enumerable' pattern. Method `IList.GetEnumerator()' is ambiguous with method `ICounter.GetEnumerator()' // Line: 26 // Compiler options: -warnaserror -warn:2 using System; using System.Collections; interface IList { IEnumerator GetEnumerator (); } interface ICounter { IEnumerator GetEnumerator (); } interface IListCounter: IList, ICounter { } class Test { static void Foo (IListCounter t) { foreach (var e in t) { } } }