Dialyzer error with NimbleCSV.RFC4180

[sonic182]

I have an error with dialyzer, by using this dummy parse_stream, I'm obtaining no local return

defmodule MyMod

  @spec base_stream(binary) :: Enumerable.t()
  def base_stream(srcfile) do
    srcfile
    |> File.stream!([:read, :compressed, :utf8, read_ahead: 10_000])
    |> NimbleCSV.RFC4180.parse_stream(skip_headers: false)
  end

end

Finding suitable PLTs
Checking PLT...
...
PLT is up to date!
No :ignore_warnings opt specified in mix.exs and default does not exist.

Starting Dialyzer
[
  check_plt: false,
  init_plt: ~c"/app/_build/dev/dialyxir_erlang-26.0.2_elixir-1.15.4_deps-dev.plt",
  files: [...],
  warnings: [:unknown]
]
Total errors: 9, Skipped: 0, Unnecessary Skips: 0
done in 0m5.13s

...
________________________________________________________________________________
lib/tasks/image_captioning/prepare_image.ex:166:no_return
Function base_stream/1 has no local return.
________________________________________________________________________________

...

________________________________________________________________________________
done (warnings were emitted)
Halting VM with exit status 2
zsh returned exit code 2

My real codes is more or less:

defmodule Foo

  def run(srcfile) do
    [["1", "foo"]]
    # srcfile
    # |> base_stream()
    |> Stream.map(fn [id, image_link] -> %{"id" => id, "image_link" => image_link} end)
    |> ...
  end

end

If I use the dummy example [["1", "foo"]] dialyzer doesn't fail, if I use it with the base_stream it fails. Any idea how to overcome this? I think it is a bug in RFC4180 parser definition

[josevalim]

This project performs code generation and it may generate code that Dialyzer sees as dead code. We don't use dialyzer in this project, but a PR is welcome if you want to address the issue. Maybe adding quote generated: true do to some of the code generation will address it.