==== tests/cases/compiler/indexerAssignability.ts (3 errors) ====
    var a: { [s: string]: string; };
    var b: { [n: number]: string; };
    var c: {};
    
    a = b;
    ~
!!! Type '{ [x: number]: string; }' is not assignable to type '{ [x: string]: string; }':
!!!   Index signature is missing in type '{ [x: number]: string; }'.
    a = c;
    ~
!!! Type '{}' is not assignable to type '{ [x: string]: string; }':
!!!   Index signature is missing in type '{}'.
    b = a;
    b = c;
    ~
!!! Type '{}' is not assignable to type '{ [x: number]: string; }':
!!!   Index signature is missing in type '{}'.
    c = a;
    c = b;