Elixir: error with OTP 21.0-rc1 and iex

[ckampfe]

Unclear if this is an issue with my environment or the RC or Elixir, but wanted to report in any case just to be sure :) Thank you!

Environment

• Elixir & Erlang/OTP versions (elixir --version): 1.6.4 (via kiex)
• Operating system: OSX 10.13.4

Current behavior

Installed Erlang 21.0-rc1 via kerl, stacktrace when trying to boot iex:

xcxk066$> kerl build git https://github.com/erlang/otp.git OTP-21.0-rc1 21.0-rc1
Checking out Erlang/OTP git repository from https://github.com/erlang/otp.git...
Building Erlang/OTP 21.0-rc1 from git, please wait...
DOCUMENTATION INFORMATION (See: /Users/xcxk066/.kerl/builds/21.0-rc1/otp_build_git.log)
 * documentation  :
 *                  fop is missing.
 *                  Using fakefop to generate placeholder PDF files.
Erlang/OTP 21.0-rc1 from git has been successfully built
xcxk066$> kerl install 21.0-rc1 21.0-rc1
Installing Erlang/OTP git (21.0-rc1) in /Users/xcxk066/code/21.0-rc1...
You can activate this installation running the following command:
. /Users/xcxk066/code/21.0-rc1/activate
Later on, you can leave the installation typing:
kerl_deactivate
[~/code]
xcxk066$> . /Users/xcxk066/code/21.0-rc1/activate
[~/code]
xcxk066$> iex
Erlang/OTP 21 [RELEASE CANDIDATE 1] [erts-10.0] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe]

=SUPERVISOR REPORT==== 2-May-2018::18:45:55.493546 ===
    supervisor: {local,'Elixir.Logger.Supervisor'}
    errorContext: start_error
    reason: noproc
    offender: [{pid,undefined},
               {id,'Elixir.Logger.ErrorHandler'},
               {mfargs,
                   {'Elixir.Logger.Watcher',start_link,
                       [{error_logger,'Elixir.Logger.ErrorHandler',
                            {true,false,500}}]}},
               {restart_type,permanent},
               {shutdown,5000},
               {child_type,worker}]
=CRASH REPORT==== 2-May-2018::18:45:55.497980 ===
  crasher:
    initial call: application_master:init/4
    pid: <0.91.0>
    registered_name: []
    exception exit: {{shutdown,
                         {failed_to_start_child,'Elixir.Logger.ErrorHandler',
                             noproc}},
                     {'Elixir.Logger.App',start,[normal,[]]}}
      in function  application_master:init/4 (application_master.erl, line 134)
    ancestors: [<0.90.0>]
    message_queue_len: 1
    messages: [{'EXIT',<0.92.0>,normal}]
    links: [<0.90.0>,<0.42.0>]
    dictionary: []
    trap_exit: true
    status: running
    heap_size: 610
    stack_size: 27
    reductions: 224
  neighbours:

=CRASH REPORT==== 2-May-2018::18:45:55.493527 ===
  crasher:
    initial call: Elixir.Logger.Watcher:init/1
    pid: <0.98.0>
    registered_name: []
    exception exit: noproc
      in function  gen:do_for_proc/2 (gen.erl, line 228)
      in call from gen_event:rpc/2 (gen_event.erl, line 239)
      in call from 'Elixir.Logger.Watcher':init/1 (lib/logger/watcher.ex, line 23)
      in call from gen_server:init_it/2 (gen_server.erl, line 374)
      in call from gen_server:init_it/6 (gen_server.erl, line 342)
    ancestors: ['Elixir.Logger.Supervisor',<0.92.0>]
    message_queue_len: 0
    messages: []
    links: [<0.93.0>]
    dictionary: []
    trap_exit: true
    status: running
    heap_size: 376
    stack_size: 27
    reductions: 269
  neighbours:

=INFO REPORT==== 2-May-2018::18:45:55.499424 ===
    application: logger
    exited: {{shutdown,
                 {failed_to_start_child,'Elixir.Logger.ErrorHandler',noproc}},
             {'Elixir.Logger.App',start,[normal,[]]}}
    type: temporary
Interactive Elixir (1.6.4) - press Ctrl+C to exit (type h() ENTER for help)

For additional context:

xcxk066$> . /Users/xcxk066/code/21.0-rc1/activate
[~]
xcxk066$> erl
Erlang/OTP 21 [RELEASE CANDIDATE 1] [erts-10.0] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:1] [hipe]

Eshell V10.0  (abort with ^G)
1> 1 + 1.
2
2>

xcxk066$> . ~/kerl/20.3-builtdocs/activate
[~/code]
xcxk066$> iex
Erlang/OTP 20 [erts-9.3] [source] [64-bit] [smp:8:8] [ds:8:8:10] [async-threads:10] [hipe] [kernel-poll:false]

Interactive Elixir (1.6.4) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)>

[michalmuskala]

We don't officially support OTP 21 yet. The next patch version of 1.6 branch should include minimal changes to make it work with 21, and 1.7 might include new features leveraging things introduced in 21.

[ckampfe]

Ahh, I had no idea. This is good to know, thank you!

[josevalim]

Closing in favor of #7646.