// CS1110: `C.Foo(this string)': Extension methods cannot be declared without a reference to System.Core.dll assembly. Add the assembly reference or remove `this' modifer from the first parameter
// Line: 7
-// Compiler options: -noconfig
+// Compiler options: -noconfig -langversion:linq
static class C
{
static void Foo (this string s)
{
}
-}
\ No newline at end of file
+}