Pathname#realdirpath

static VALUE
path_realdirpath(int argc, VALUE *argv, VALUE self)
{
    VALUE basedir, str;
    rb_scan_args(argc, argv, "01", &basedir);
    str = rb_funcall(rb_cFile, id_realdirpath, 2, get_strpath(self), basedir);
    return rb_class_new_instance(1, &str, rb_obj_class(self));
}