Overriding Worker.new results in a compilation warning

[arjan]

• Oban Version: any
• PostgreSQL Version: n/a
• Elixir & Erlang/OTP Versions: OTP 26, Elixir 1.15, 1.16

Current Behavior

When creating a custom new/2 function on a worker, a compilation warning is raised. Easily reproducible with this script:

Mix.install([:oban])

defmodule MyWorker do
  use Oban.Worker

  @impl Oban.Worker
  def new(args, opts \\ []) do
    Map.put(args, "foo", 1)
    super(args, opts)
  end

  @impl Oban.Worker
  def perform(_), do: :ok
end

The warning that is thrown is this one:

    warning: this clause for new/1 cannot match because a previous clause at line 4 always matches
    │
  7 │ 
    │ 
    │
    └─ /home/arjan/.cache/mix/installs/elixir-1.16.1-erts-14.0.2/a89644f639a5a591d0aea0a967f470fd/deps/oban/lib/oban/worker.ex:7

I think it has to do with the defaults on the second argument.
The warning goes away if I add a @callback declaration for the new/1 in Oban.Worker, next to the existing callback:

  @callback new(args :: Job.args()) :: Job.changeset()

But I am not sure that this is a proper solution.

[sorentwo]

Setting default opts defines both a new/1 and new/2, and it correctly warns that new/1 already exists.

You should only define new/2:

  @impl Oban.Worker
  def new(args, opts) do
    args
    |> Map.put(:foo, 1)
    |> super(opts)
  end

That clause will still be used when you call MyWorker.new(args).

[arjan]

Ah yes, of course, thanks for the explanation!