Support Erlang/OTP 25 new features

[josevalim]

To be implemented when Erlang 25 is released:

• [x] Format terms in binary construction error message (https://github.com/erlang/otp/pull/5281)
• [x] Improved error messages in evaluation (https://github.com/erlang/otp/pull/5631)
• [x] Add pretty printing from EEP 54 (https://github.com/erlang/otp/pull/5752)
• [x] Add compile attribute -nifs

To be implemented when we require Erlang 25 exclusively:

• [x] Use "undefined" as node name for remote/rpc and document -start_epmd false -erl_epmd_port 6789 on both vm.args/remote.vm.args if you need epmdless
• [x] Use :erlang.float_to_binary([:short]) in Float.to_string/1 instead of private API
• [x] Use new format_status/1 callback for GenServer
• [x] Remove the calling_self clause in GenServer.call as that is now in Erlang/OTP
• [x] Use new system certificates

Please do not send PRs for those, as it will take a while until we can effectively accept them.

[hauleth]

Erlang 25 will also support reconfiguration of logger, which will allow us to use config :kernel, :logger, […] in development and releases without need for restarting whole init (https://github.com/erlang/otp/pull/5186).

[nathany-copia]

Do you want a separate issue for compiling with OTP 25? This is from GitHub CI, and I tried clearing the CI cache, but it may be related to a NIF?

Running mix local.rebar,--force
  /home/runner/work/_temp/.setup-beam/elixir/bin/mix local.rebar --force
  
  Error: 7.616 [error] beam/beam_load.c(86): Error loading module 'Elixir.Code.Formatter':
  Warning:   lambda already defined for label 749. To fix this, please recompile this module with an OTP 25 compiler.
  
  Error: 7.616 [error] Loading of /home/runner/work/_temp/.setup-beam/elixir/bin/../lib/elixir/ebin/Elixir.Code.Formatter.beam failed: :badfile
  
  ** (UndefinedFunctionError) function Code.Formatter.locals_without_parens/0 is undefined (module Code.Formatter is not available)
      (elixir 1.13.4) Code.Formatter.locals_without_parens()
      (elixir 1.13.4) lib/code/normalizer.ex:22: Code.Normalizer.normalize/2
  Warning:     (elixir 1.13.4) lib/code.ex:1107: Code.quoted_to_algebra/2
  Error: The process '/home/runner/work/_temp/.setup-beam/elixir/bin/mix' failed with exit code 1

[josevalim]

You are using a precompiled Elixir version. It is just a matter of time until we have precompiled versions for OTP 25. It is usually tackled automatically by build tools. You can also compile it yourself.

[nathany-copia]

Thanks. I've opened an issue with erlef/setup-beam.

https://github.com/erlef/setup-beam/issues/117

[dvic]

I noticed there were also changes to the gen_server application (among others): https://github.com/erlang/otp/pull/5792 Is this something that we need to pull into Elixir as well?

[josevalim]

Our goal is to use the task API for that. We will see how it will go once we support it in OTP 24.

[henrythebuilder]

Note for compile attribute -nifs:

reference: erlang/otp pull request 'compiler: Start all potential nif functions with a nif_start #6193', merged on erlang/otp:master

the pull request change the way attribute -nifs is considered (optional ?):

... Due to backwards compatibility, the nifs attribute is not required, so when a module containing a call to erlang:load_nif/2 is encountered, the compiler is forced to conservatively assume that in such a module, all functions are potential nifs ... ... This patch extends the v3_core-pass to make all functions start with a nif_start instruction when the nifs attribute isn't present in the module but a call to erlang:load_nif/2 is. ...

[michalmuskala]

Would it make sense to add support for the -nifs attribute already?

I believe it would be fine to always emit it as a persisted attribute - it would be just ignored on older OTP releases.

I had to do some ugly hacks to get the support in the current version https://github.com/spawnfest/json_native/blob/main/lib/jason_native.ex#L10-L13

[josevalim]

Yes, we can definitely support it. A PR is welcome!

[michalmuskala]

I looked into this a bit. It's not particularly complicated, but we do need to port validation rules from erl_lint (since Elixir skips running the checks there). In particular, it collects information if there's a call to erlang:load_nif anywhere inside the module

[LostKobrakai]

I'm wondering why the following task requires "OTP 25 exclusively"? Afaik the functionality had been in OTP since 23.

Use "undefined" as node name for remote/rpc and document -start_epmd false -erl_epmd_port 6789 on both vm.args/remote.vm.args if you need epmdless

[josevalim]

I don't remember the details but I tried to add it on main and ran into issues for the RPC case. The rest of the support is already in and you can use undefined in main.

[josevalim]

Next Elixir version will depend on OTP 25+26+27, so we can start tackling this one.