I’m checking on how to make my Elixir code more refactorable and for that reason testing Gradualizer with @OvermindDL1’s gradualixir package.

Suppose I have the following module type “Stuff”:

@type t() :: %Types.Stuff{foo: String.t()}

And the following function with a signature:

  @spec check_gradualizer() :: Types.Stuff.t()
  def check_gradualizer() do
    %TimeclockParser.Types.Stuff{
      foo: 1
    }
  end

Gradualizer will report, correctly, that I tried to make foo a number, while it is actually a String.t.

But if I simply assign the struct creation to a variable and return that:

  @spec check_gradualizer() :: Types.Stuff.t()
  def check_gradualizer() do
    entry = %TimeclockParser.Types.Stuff{
      foo: 1
    }

    entry
  end

I get no reports whatsoever. Is this expected? A usage error? Or simply a bug?