Engine is compiled with system Erlang, despite using Mise (MacOS, fish)

[katafrakt]

OS: MacOS Tahoe
Editor: Emacs / eglot
Shell: fish
Expert version: built from git
Version manager: mise

This is probably very niche, but Expert stopped working for me today at all. Whenever it tries to start, after compiling the engine it fails with something like:

3:06:42.859 [debug] Node port message: 
13:06:42.851 [error] beam/beam_load.c(150): Error loading module 'Elixir.XPForge.NodePortMapper':
  corrupt atom table



13:06:42.865 [debug] Node port message: 
13:06:42.865 [error] beam/beam_load.c(150): Error loading module 'Elixir.XPForge.EPMD':
  corrupt atom table

Even worse, now when I try to do anything in my project, I'm getting similar error with Error loading module 'Elixir.Hex. Every time, I need to mix local.hex --force.

After some digging I found that when engine building does it's own mix local.hex --force, it does that in Elixir 1.19.4-otp27 directory, but using Erlang/OTP 28 installed from Homebrew. Even further down the line, I found that Expert.Port when detecting fish, in path_Env_at_directory, starts a new fish shell using fish -l -c, which modifies the path. This is probably because -l reevaluates fish config, runs eval "$(/opt/homebrew/bin/brew shellenv)" from ~/.config/fish/conf.d/env.fish` (I believe this is autogenerated by Homebrew, as I don't recall creating this file).

As a result, the beginning of path when I run echo $PATH in my shell:

/Users/pawel.sw/.opam/4.14.0/bin /Users/pawel.sw/Downloads/google-cloud-sdk/bin /Users/pawel.sw/.local/share/mise/installs/elixir/1.19.4-otp-27/bin

but when I log the path in Expert.Port, after path_env_in_directory, it is:

/opt/homebrew/bin:/opt/homebrew/sbin:/Users/pawel.sw/.local/bin:/Users/pawel.sw/dev/lexical/_build/dev/package/lexical/bin

The directories are in a completely different order, and indeed, erl now points to the Homebrew installation.

The issue also manifests in log file with this message:

12:43:20.143 [debug] Building engine: * creating /Users/pawel.sw/.local/share/mise/installs/elixir/1.19.4-otp-27/.mix/archives/hex-2.3.1-otp-28

12:43:20.673 [debug] Building engine: * creating /Users/pawel.sw/.local/share/mise/installs/elixir/1.19.4-otp-27/.mix/elixir/1-19-otp-28/rebar3 

(OTP 28 in OTP 27 directory)

Solution

After trying out few things I found that changing this line into ["--no-config", "-c", cmd] fixes the issue. The PATH is now inherited from parent process and correct Erlang version (from mise) is picked. It looks to me like a safe change to make, but I wanted to discuss this first, because I don't know the whole history behind the PATH handling here.

[katafrakt]

What is strange is that I cannot reproduce it in VSCode. I see that the PATH gets modified when doing fish -l -c, but to much smaller extent and mise paths remain before homebrew paths. I have no idea what's the difference.