Issue with auto-completion when dialyzer is disabled for an umbrella app

[akash-akya]

Environment

Erlang/OTP 21 [erts-10.3] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [hipe]
Elixir 1.7.3 (compiled with Erlang/OTP 21)

Language server version: v0.3.3

MacOS Mojave, Emacs with eglot as LS client

Issue

Elixir LS fails to return autocompletion results for umbrella application when dialyzer is disabled

Reproducing the issue

• clone https://github.com/akash-akya/elixir-ls-test
• open project with dialyzer disabled, with emacs and eglot, dialyzer is disabled by default using .dir-locals.el.
• let elixir-ls build and generate .beam files
• open apps/foo/lib/foo.ex and type Core.Bar this should trigger auto-completion and it should show Core.BarServer as suggestion
• close the project and open it again
• try the same auto-completion as before, this time it won't show the suggestion

My best guess is, it is something to do with not triggering complete project compilation when we reopen the project.

[lukaszsamson]

I think it's related to the quirky way elixir-ls loads user modules. See https://github.com/elixir-lsp/elixir-ls/blob/master/guides/initialization.md#analyzing-the-project for details.

TLDR;
When dialyzer is not enabled Modules are not properly loaded and cannot be analysed hence no completions.

[akash-akya]

I see, thanks for the quick response.

We have a big umbrella project, so I have to turn off the dialyzer.
For now, I'm using this ugly hack and so far it seems to work.

[axelson]

@akash-akya thanks for showing the patch/hack you're using, that is helpful. Could you try replacing most of it by Keyword.fetch!(Mix.Project.config(), :app) |> Application.load()

[akash-akya]

Hi @axelson, I thought of something similar, but this does not works, as mix file of the project is not loaded yet. Basically :app will be nil.

I tried using Mix.Project.in_project to fix this. something like

  defp load_modules(state) do
    guessed_project_name = Path.basename(state.project_dir)

    Mix.Project.in_project(String.to_atom(guessed_project_name), state.project_dir, fn _project ->
      if Mix.Project.umbrella?() do
        Mix.Project.apps_paths()
        |> Map.keys()
        |> Enum.each(&Application.load/1)
      else
        Keyword.fetch!(Mix.Project.config(), :app)
        |> Application.load()
      end
    end)

    %{state | modules_loaded?: true}
  end

This does load the project, but now we get a compilation error when the compiler tries to build,

== Compilation error in file mix.exs ==
** (CompileError) mix.exs:1: cannot define module RheaUmbrella.Mixfile because it is currently being defined in /Users/akash/repo/rhea/mix.exs:1
    (stdlib) erl_eval.erl:680: :erl_eval.do_apply/6

Moreover, I think this does not load modules from.elixir-ls build path. The default build path is often outdated.

[axelson]

Hmmm, okay. It would be great to fix this, but we would want to find a less hacky way if possible :)