=== tests/cases/compiler/overloadWithCallbacksWithDifferingOptionalityOnArgs.ts ===
function x2(callback: (x?: number) => number);
>x2 : { (callback: (x?: number) => number): any; (callback: (x: string) => number): any; }
>callback : (x?: number) => number
>x : number

function x2(callback: (x: string) => number);
>x2 : { (callback: (x?: number) => number): any; (callback: (x: string) => number): any; }
>callback : (x: string) => number
>x : string

function x2(callback: (x: any) => number) { }
>x2 : { (callback: (x?: number) => number): any; (callback: (x: string) => number): any; }
>callback : (x: any) => number
>x : any

x2(() => 1);
>x2(() => 1) : any
>x2 : { (callback: (x?: number) => number): any; (callback: (x: string) => number): any; }
>() => 1 : () => number
>1 : number

x2((x) => 1 );
>x2((x) => 1 ) : any
>x2 : { (callback: (x?: number) => number): any; (callback: (x: string) => number): any; }
>(x) => 1 : (x: number) => number
>x : number
>1 : number