=== tests/cases/compiler/optionalParamReferencingOtherParams1.ts ===
function strange(x: number, y = x * 1, z = x + y) {
>strange : (x: number, y?: number, z?: number) => number
>x : number
>y : number
>x * 1 : number
>x : number
>z : number
>x + y : number
>x : number
>y : number

    return z;
>z : number
}