=== tests/cases/compiler/functionOverloads25.ts ===
function foo():string;
>foo : { (): string; (bar: string): number; }

function foo(bar:string):number;
>foo : { (): string; (bar: string): number; }
>bar : string

function foo(bar?:any):any{ return '' };
>foo : { (): string; (bar: string): number; }
>bar : any

var x = foo();
>x : string
>foo() : string
>foo : { (): string; (bar: string): number; }