==== tests/cases/compiler/functionTypeArgumentArrayAssignment.ts (1 errors) ====
    interface Array<T> {
        foo: T;
        length: number;
     ~~~~~~
!!! functionTypeArgumentArrayAssignment.ts(3,2): error TS2000: Duplicate identifier 'length'. Additional locations:
!!! 	lib.d.ts(974,5)
    }
    
    function map<U>() {
    var ys: U[] = [];
    }
    