//// [icomparable.ts]
    interface IComparable<T> {
       compareTo(other: T);
    }

    declare function sort<U extends IComparable<any>>(items: U[]): U[];

    interface StringComparable extends IComparable<string> {
    }

    var sc: StringComparable[];

    var x = sort(sc);

//// [icomparable.js]
var sc;
var x = sort(sc);