No case clause matching when using IEx.break!

[deviprsd]

Elixir and Erlang/OTP versions

erlang 26.1.2
elixir 1.15.7 // or 1.15.7-otp-26

Operating system

MacOS

Current behavior

I'm setting a break point in iex -S mix phx.server, this is happening in a liveview process and while I'm using Ash, it might have to do more with elixir.

iex(2)> break! Data.Account.Space.Action.GetByCodename.read/4

When I trigger the break by opening the appropriate view, I'm getting this error.

** (CaseClauseError) no case clause matching: {:line, :infinity}
    (elixir 1.15.7) src/elixir.erl:250: :elixir.env_for_eval/1
    (iex 1.15.7) lib/iex/pry.ex:84: IEx.Pry.pry/2
    (iex 1.15.7) lib/iex/pry.ex:89: IEx.Pry.pry_with_next/3
    (data 0.1.0) Data.Account.Space.Action.GetByCodename.read/4
    (ash 2.17.3) lib/ash/actions/read.ex:2869: Ash.Actions.Read.run_query/6
    (ash 2.17.3) lib/ash/actions/read.ex:1449: anonymous fn/4 in Ash.Actions.Read.data_field/3
    (ash 2.17.3) lib/ash/engine/engine.ex:537: anonymous fn/2 in Ash.Engine.run_iteration/1
    (ash 2.17.3) lib/ash/engine/engine.ex:558: anonymous fn/4 in Ash.Engine.async/2

Module code,

defmodule Data.Account.Space.Action.GetByCodename do
  require Ash.Query
  use Ash.Resource.ManualRead

  def read(query, _data_layer_query, _opts, _context) do
    {:ok, []}
  end
end

Expected behavior

Not throw this error and enter pry session

[josevalim]

@deviprsd can you reproduce it outside of an Ash module? If you cannot, this may be an Ash bug, so I would appreciate help isolating the bug so it doesn't depend on Ash. Thank you!

[zachdaniel]

It seems interesting…I’m not sure if any of our metaprogramming would come into play here as all we ultimately do is call that module. I agree though, Ash should be eliminated as a factor here, although I’m not sure how that could be done. What even produces {:line, :infinity}?

[zachdaniel]

@deviprsd are you calling the action using the code interface? Perhaps trying using a query/api call directly if so.

[deviprsd]

@zachdaniel I'm using code interface, it looks something like this.

code_interface do
    define :get_by_codename, action: :by_codename, args: [...args]
end

read :by_codename do
    get? true
    # ...args
    manual GetByCodename
end

I tried this, still the same error.

Space |> Ash.Query.for_read(:by_codename, %{codename: id}) |> Data.Account.read()

[zachdaniel]

So that eliminates any code generation as the culprit then. 🤔 try this. In iex do the following before trying to set your break: Code.ensure_compiled!(TheReadModule) (would type it out but I'm on my phone).

[deviprsd]

Well I'm guessing you mean my ManualRead module here, but just to be sure I did that for the api and resource as well

Code.ensure_compiled!(Data.Account.Space.Action.GetByCodename)
Code.ensure_compiled!(Data.Account.Space)
Code.ensure_compiled!(Data.Account)
break! Data.Account.Space.Action.GetByCodename.read/4

Same error

[zachdaniel]

Here is a minimal reproduction not using any libraries at all.

If you uncomment the work/0 function that fixes both cases, so it seems like it has something to do with not knowing about compile time dependencies or something along those lines. Regardless, the break/0 function seems like it should be a supported use case? never mind, it breaks in both cases, false alarm.

So I don't have a working version of this actually. But the issue is pretty clearly reproduced I think.

Using this project, do the following in ex

iex(1)> break! AnAdopter.read
1
iex(2)> Break.break
** (CaseClauseError) no case clause matching: {:line, :infinity}
    (iex 1.15.4) lib/iex/pry.ex:84: IEx.Pry.pry/2
    (iex 1.15.4) lib/iex/pry.ex:89: IEx.Pry.pry_with_next/3
    (break 0.1.0) AnAdopter.read/0

https://github.com/zachdaniel/breakpoint-broken-example/blob/main/lib/break.ex

[josevalim]

This minimal example is perfect and exactly what I needed. Thank you.