According to this answer (https://stackoverflow.com/a/52761156/599184), ReturnType<> doesn't work with overloaded functions in general. However, would it be possible to select a particular version of the overloaded function and get its return type?

The only way I can think of is to have code invoking the overloaded function.

function fn(arg: string): string;

function fn(arg: number): number;

function fn(arg: string | number): string | number {
    return arg;
}

const temp1 = () => fn('string');
type Type1 = ReturnType<typeof temp1>; // string

const temp2 = () => fn(123);
type Type2 = ReturnType<typeof temp2>; // number

TS Playground

Is there a cleaner way where I don't have to pass in the arguments (just the argument type)?