Support Erlang/OTP 24 new features

[josevalim]

To be implemented when Erlang 24 is released:

• Use os:env/0 in System.get_env/0 (requires a function_exported? check)
• The OTP breaking change to stacktraces requires rebar3 to ship multiple compiled binaries, we need to align with this on mix local.rebar
• Support EEP 54
• Support float-16
• Use maps on erl_eval
• Emit error_info from Elixir exceptions (Extend and document exceptions and error_info erlang/otp#4764)
• maps:from_keys/2

To be implemented when we require Erlang 24 exclusively (from v1.15):

• Use from_abstr+no_lint (see Make compiler accept abstract format as input erlang/otp#3019) (not possible, overrides debug_info)
• Use sets (v2) in MapSet
• Generate :optional_applications key in .app
• Add nonempty_binary and nonempty_bitstring to typespecs
• Add Process.alias/1 and Process.monitor/2 (EEP 53)
• See if we can integrate :gen_server.wait_response/check_response/receive_response as tasks (not possible, it requires custom gen replies)
• Support shutdown of zero (Fix bug DynamicSupervisor child_spec validation #11836)

[hauleth]

I think that thanks to @DianaOlympos we can also use float formatters from Erlang in OTP 24, the implementations should now be exactly the same in both languages.

[josevalim]

@hauleth I believe there is nothing to be done on that front since we already use the relevant APIs, i.e. io_lib_format:fwrite_g. :)

[DianaOlympos]

Yeah even if it is a private API that is undocumented .... 😄

[hauleth]

@DianaOlympos and I was doing my best to avoid non-public API in Logger… Ehhhh…

Jokes aside - additional point can be added - translating :console logger to be Erlang handler instead of Elixir backend (also tracked in #9465).

[DianaOlympos]

@hauleth technically you can use the io:fwrite API with the correct options, but people just called :io_lib_format:fwrite_g/1 instead. Which will be fixed soon as i work on making it a BIF anyway.

[lukaszsamson]

Can we add nonempty_binary and nonempty_bitstring?

[josevalim]

Added to the list, thanks!

[hauleth]

We should also add support for global Logger metadata to the list.

[otijhuis]

I was curious about supporting EEP-56. (Erlang OTP/24 release notes: Implementation of EEP 56 in supervisor. It adds the concept of significant children as well as the auto_shutdown supervisor flag. See the supervisor manual page for more information.)

EEP-56 is mentioned in 'To be implemented when we require Erlang 24 exclusively' but Process.alias/1 and Process.monitor/2 seem to be part of EEP-53?

As far as I could tell from the docs, EEP-56 is a backwards compatible change. Does anything have to be added to Elixir to support this?

[josevalim]

Good catch, I got my EEPs mixed. We should support both EEP 53 and EEP 56.