[Issue 15280] Unable to factor two simple functions into one inout function

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=15280

--- Comment #1 from Sobirari Muhomori <dfj1esp02 at sneakemail.com> ---
One const method looks enough in your case:

    List tail() const
    {
        assert(root);
        auto n = root.next;
        return List(n);
    }

--