There’s a 0.22.0-rc.1 release that got out like 45 minutes ago.

@maciejgryka What you have shown have worked for me for Elixir 1.12.0-otp-24 and Erlang 24.0.1. Thanks!

(I still used rustler from the master branch, though.)

Which version of rustler are you using? Mine is 0.22.0-rc.0. My Elixir+Rust project compiles fine with Erlang 23.3.4 and Elixir 1.12.0-otp-23, but fails to compile with Erlang 24.0 and Elixir 1.12.0-otp-24. The error is:

Caused by:
  process didn't exit successfully: `/Users/dimi/kod/xqlite/_build/dev/rustler_crates/xqlitenif/release/build/rustler-69fb4c768ce25323/build-script-build` (exit code: 101)
  --- stderr
  thread 'main' panicked at 'Erlang version 2.16 not handled, please file a a bug report.', /Users/dimi/.cargo/registry/src/github.com-1ecc6299db9ec823/rustler-0.22.0-rc.0/build.rs:36:10
  note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
warning: build failed, waiting for other jobs to finish...
error: build failed
** (RuntimeError) Rust NIF compile error (rustc exit code 101)
    (rustler 0.22.0-rc.0) lib/mix/tasks/compile.rustler.ex:89: Mix.Tasks.Compile.Rustler.compile_crate/1
    (elixir 1.11.4) lib/enum.ex:1411: Enum."-map/2-lists^map/1-0-"/2
    (rustler 0.22.0-rc.0) lib/mix/tasks/compile.rustler.ex:28: Mix.Tasks.Compile.Rustler.run/1
    (mix 1.11.4) lib/mix/task.ex:394: Mix.Task.run_task/3
    (mix 1.11.4) lib/mix/tasks/compile.all.ex:90: Mix.Tasks.Compile.All.run_compiler/2
    (mix 1.11.4) lib/mix/tasks/compile.all.ex:70: Mix.Tasks.Compile.All.compile/4
    (mix 1.11.4) lib/mix/tasks/compile.all.ex:57: Mix.Tasks.Compile.All.with_logger_app/2
    (mix 1.11.4) lib/mix/tasks/compile.all.ex:35: Mix.Tasks.Compile.All.run/1

Seems there’s a hard requirement for a maximum Erlang version. I thought of contributing and maybe even taking over rustler in the future (the owners are semi-open to the idea btw) but life and work keep getting in the way.

Still, maybe I can muster a small PR that fixes this problem soon-ish.

TL;DR: It’s not Elixir 1.12.0’s fault. It seems to be rustler insisting on a maximum Erlang version.

I still have problems, not fully resolved. but at least The main branch of rustler is updated for OTP-24

Could not compile :rustler, no "mix.exs", "rebar.config" or "Makefile" (pass :compile as an option to customize compilation, set it to "false" to do nothing)
==> meeseeks_html5ever
Could not compile :rustler, no "mix.exs", "rebar.config" or "Makefile" (pass :compile as an option to customize compilation, set it to "false" to do nothing)
Unchecked dependencies for environment prod:
* rustler (https://github.com/rusterlium/rustler.git)
  the dependency build is outdated, please run "MIX_ENV=prod mix deps.compile"
could not compile dependency :meeseeks_html5ever, "mix compile" failed. You can recompile this dependency with "mix deps.compile meeseeks_html5ever", update it with "mix deps.update meeseeks_html5ever" or clean it with "mix deps.clean meeseeks_html5ever"

I had the same problem - it all seems to work after you use the git checkout option both in your mix.exs as well as Cargo.toml (a short blog post about this here).

I was missing the Cargo.toml step for a long time leading me to being stuck with 0.22.0-rc.0 there and still getting the version error.

To summarize, I’ve added this to mix.exs (thanks for the sparse tip @josevalim):

{:rustler, git: "git://github.com/rusterlium/rustler.git", branch: "master", sparse: "rustler_mix"},

And this to Cargo.toml:

rustler = {git = "git://github.com/rusterlium/rustler.git", branch="master"}

I am now using Erlang 24.0 and Elixir 1.12.0-otp-24 plus I use rustler directly from its GitHub repo and I am still getting the error. Which versions do you have exactly so it’s working for you?