erlc_options should behave more like elixirc_options

[hauleth]

Environment

• Elixir & Erlang/OTP versions (elixir --version):

Erlang/OTP 22 [erts-10.4.3] [source] [64-bit] [smp:12:12] [ds:12:12:10] [async-threads:1] [hipe]

Elixir 1.8.2 (compiled with Erlang/OTP 22)

• Operating system: macOS Mojave

Current behavior

There difference in behaviour of :elixirc_options and :elrc_options. This is the inclusion of :debug_info. In :elixirc_options it is added always (or at least seems so when running Dialyzer) while in :erlc_options it need to be explicitly stated, otherwise Dialyzer will fail with information that it cannot find Erlang Core informations.

Example repo: https://github.com/hauleth/example_error

Way to reproduce error:

mix do compile --force, dialyzer

Way to resolve error:

env DEBUG_INFO=1 mix do compile --force, dialyzer

Expected behavior

Mix should always add :debug_info option or should provide different way to ensure, that this is handled properly. Otherwise it has limited capabilities as the Erlang projects build tool.

[kelvinst]

If we automatically add :debug_info to the list of options, there would be no way to compile it without that. Any idea? Maybe another :no_debug_info option that we handle on the mix task to not include :debug_info?

[kelvinst]

One option though would be to make the docs clearer regarding the need to add :debug_info if you are setting that config, since it is the default value but not automatically added.

[kelvinst]

I say that because some people might want to disable it to make compilation faster (not even sure how faster it would be though). That makes me wonder if there is a way to do the same for elixir compiler, and if we should actually have that.

[josevalim]

The elixir compiler supports :no_debug_info so we should probably do the same here. -- *José Valim* www.plataformatec.com.br Skype: jv.ptec Founder and Director of R&D

[kelvinst]

The elixir compiler supports :no_debug_info so we should probably do the same here.

I'm just curious how, because I don't see that anywhere on the codebase. Anyway, I can work on a PR for this.

[josevalim]

Hrm, I may be misremembering then. Perhaps it is debug_info: false? It would be in elixir_erl.erl or similar. :)

[kelvinst]

Perhaps it is debug_info: false?

Yep, that's it: https://github.com/elixir-lang/elixir/blob/master/lib/elixir/lib/code.ex#L979-L981

What is strange is that it says the default value for it is false. 🤷‍♂ I think the docs there are just wrong, tested on a empty new project:

iex(1)> Code.get_compiler_option(:debug_info)
true

[josevalim]

Oh, good catch, let’s fix the docs too! -- *José Valimwww.plataformatec.com.br <http://www.plataformatec.com.br/>Founder and Director of R&D*

[kelvinst]

I've just checked and actually the options [{:debug_info, false}, :debug_info] are valid ones and it reads false for :debug_info, so just adding the :debug_info here is enough, and if anyone wants to disable :debug_info just have to set debug_info: false on the project :erlc_options.

PR coming soon.