https://github.com/mhanberg/with_dialyzer

https://github.com/mhanberg/with_dialyzer

Last synced: about 1 month ago
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• Host: GitHub
• URL: https://github.com/mhanberg/with_dialyzer
• Owner: mhanberg
• Created: 2024-02-14T17:31:05.000Z (9 months ago)
• Default Branch: main
• Last Pushed: 2024-02-14T17:36:31.000Z (9 months ago)
• Last Synced: 2024-05-01T13:52:30.186Z (7 months ago)
• Language: Elixir
• Size: 2.93 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# WithDialyzer

Demo of a dialyzer warning that I believe is caused by a new way of compiling the `with` special form into Erlang

Using the versions

```

erlang = "26.2.2"

elixir = "ref:52eaf1456182d5d6cce22a4f5c3f6ec9f4dcbfd9"

```

This case I believe is somewhat interesting because according to the erlang docs, the `:inet.gethostname/0` function "never fails".

```elixir

with {:ok, host} <- :inet.gethostname() do

  host

end

```

```

lib/with_dialyzer.ex:3:pattern_match_cov

The pattern

variable_

can never match, because previous clauses completely cover the type

{:ok, [byte()]}.

```

However, if you switch this from the left stab operator to the match operator, it passes

```elixir

with {:ok, host} = :inet.gethostname() do

  host

end

```

This case was reduced from the application code

```elixir

with {:ok, host} <- :inet.gethostname(),

     node = :"#{sname}@#{host}",

     true <- connect(node, port, 120) do

  NextLS.Logger.info(logger, "Connected to node #{node}")

  :next_ls

  |> :code.priv_dir()

  |> Path.join("monkey/_next_ls_private_compiler.ex")

  |> then(&:rpc.call(node, Code, :compile_file, [&1]))

  |> tap(fn

    {:badrpc, error} ->

      NextLS.Logger.error(logger, "Bad RPC call to node #{node}: #{inspect(error)}")

      send(me, {:cancel, error})

    _ ->

      :ok

  end)

  send(me, {:node, node})

else

  error ->

    send(me, {:cancel, error})

end

```