module T::Private::Methods

def self._check_final_ancestors(target, target_ancestors, source_method_names)
  if !module_with_final?(target)
    return
  end
  # use reverse_each to check farther-up ancestors first, for better error messages. we could avoid this if we were on
  # the version of ruby that adds the optional argument to method_defined? that allows you to exclude ancestors.
  target_ancestors.reverse_each do |ancestor|
    source_method_names.each do |method_name|
      # the usage of method_owner_and_name_to_key(ancestor, method_name) instead of
      # method_to_key(ancestor.instance_method(method_name)) is not (just) an optimization, but also required for
      # correctness, since ancestor.method_defined?(method_name) may return true even if method_name is not defined
      # directly on ancestor but instead an ancestor of ancestor.
      if ancestor.method_defined?(method_name) && final_method?(method_owner_and_name_to_key(ancestor, method_name))
        raise(
          "`#{ancestor.name}##{method_name}` was declared as final and cannot be " +
          (target == ancestor ? "redefined" : "overridden in `#{target.name}`")
        )
      end
    end
  end
end