mirah overriding method bug

gistfile1.rb

class A
    def func(i:int):long
        long(i)
    end
end

class B < A
    def func(i:int):int
        i + 10
    end
end

a = A(B.new)
#b = B.new

puts a.func 5
#puts b.func 5
#puts A(b).func 5