return_type.ts

type ClassType = new (...args: any[]) => any;

function Mixin<T extends ClassType, R extends T[]>(...classRefs: [...R]): InstanceType<R[number]> {
    return null as any
}


class Foo {
    foo() { }
}

class Bar {
    bar() { }
}

class Baz {
    baz() {
        console.log('baz');
    }
}


const result = Mixin(Foo, Bar, Baz) // Foo | Bar | Baz