Weird Generic Default Argument Thing

GenericSubclass.swift

//: Playground - noun: a place where people can play

import UIKit

class Foo<T> {
    init(first: T, second: Int = 10) {}
}

class Bar: Foo<Int> {
    static func makeBar() -> Bar {
        return Bar(first: 5)
    }
}

Bar.makeBar()