strange behavior of elixir macro

macro_def.ex

defmodule FuncMacro do
  defmacro func(name) do
    quote do
      def unquote(name)(args) do
        Enum.join(args, "-")
      end
    end
  end

  defmacro func_with_body(name, do: body) do
    quote do
      def unquote(name)(args) do
        unquote(body)
      end
    end
  end
end

defmodule TestModule do
  require FuncMacro
  # This can work correctly.
  FuncMacro.func :func_without_body

  # Why this not?
  FuncMacro.func_with_body :func_with_body do
    Enum.join(args, "-")
  end
end