==== tests/cases/compiler/arraySigChecking.ts (3 errors) ====
    declare module M {
        interface iBar { t: any; }
        interface iFoo extends iBar {
            s: any;
        }
    
        class cFoo {
            t: any;
        }
    
        var foo: { [index: any]; }; // expect an error here
                    ~~~~~
!!! An index signature parameter type must be 'string' or 'number'.
    }
    
    interface myInt {
        voidFn(): void;
    }
    var myVar: myInt;
    var strArray: string[] = [myVar.voidFn()];
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!!! Type 'void[]' is not assignable to type 'string[]':
!!!   Type 'void' is not assignable to type 'string'.
    
    
    var myArray: number[][][];
    myArray = [[1, 2]];
    ~~~~~~~
!!! Type 'number[][]' is not assignable to type 'number[][][]':
!!!   Type 'number[]' is not assignable to type 'number[][]':
!!!     Type 'number' is not assignable to type 'number[]':
!!!       Property 'concat' is missing in type 'Number'.
    
    function isEmpty(l: { length: number }) {
        return l.length === 0;
    }
    
    isEmpty([]);
    isEmpty(new Array(3));
    isEmpty(new Array<string>(3));
    isEmpty(['a']);