// CS1110: `C.Foo(this string)': Extension methods require `System.Runtime.CompilerServices.ExtensionAttribute' type to be available. Are you missing an assembly reference? // Line: 7 // Compiler options: -noconfig -nostdlib static class C { static void Foo (this string s) { } } namespace System { public class Object { object value_with_no_base; } public struct Byte {} public struct Int16 {} public struct Int32 {} public struct Int64 {} public struct Single {} public struct Double{} public struct Char {} public struct Boolean {} public struct SByte {} public struct UInt16 {} public struct UInt32 {} public struct UInt64 {} public struct IntPtr {} public struct UIntPtr {} public struct Decimal { } public class String { } public class Delegate {} public class MulticastDelegate {} public class Array {} public class Exception {} public class Type {} public class ValueType {} public class Enum {} public class Attribute {} public struct Void {} public class ParamArrayAttribute {} public class DefaultMemberAttribute {} public struct RuntimeTypeHandle {} public struct RuntimeFieldHandle {} public interface IDisposable {} } namespace System.Runtime.InteropServices { public class OutAttribute {} } namespace System.Collections { public interface IEnumerable {} public interface IEnumerator {} } namespace System.Reflection { public class DefaultMemberAttribute {} }