Error: can't restrict Array(A | B) to Array(A | B)

[Blacksmoke16]

module A
end

module B
end

class C
  include A
  include B
end

class Foo
  def initialize(
    types : Array(A | B) = [] of A | B
  )
  end
end

Foo.new # => Error: can't restrict Array(A | B) to Array(A | B)

Having C that includes both A and B seems to confuse the compiler.