Prevent "current application does not depend on" compile warnings

[pzingg]

Uses the :extra_applications key in mix.exs Exposes dependencies correctly in mix.exs to prevent these warnings:

warning: Earmark.as_html!/2 defined in application :earmark is used by the current application but the current application does not depend on :earmark. To fix this, you must do one of:

  1. If :earmark is part of Erlang/Elixir, you must include it under :extra_applications inside "def application" in your mix.exs

  2. If :earmark is a dependency, make sure it is listed under "def deps" in your mix.exs

  3. In case you don't want to add a requirement to :earmark, you may optionally skip this warning by adding [xref: [exclude: [Earmark]]] to your "def project" in mix.exs

  lib/phoenix_markdown/engine.ex:35: PhoenixMarkdown.Engine.compile/2

warning: HtmlEntities.decode/1 defined in application :html_entities is used by the current application but the current application does not depend on :html_entities. To fix this, you must do one of:

  1. If :html_entities is part of Erlang/Elixir, you must include it under :extra_applications inside "def application" in your mix.exs

  2. If :html_entities is a dependency, make sure it is listed under "def deps" in your mix.exs

  3. In case you don't want to add a requirement to :html_entities, you may optionally skip this warning by adding [xref: [exclude: [HtmlEntities]]] to your "def project" in mix.exs

  lib/phoenix_markdown/engine.ex:58: PhoenixMarkdown.Engine.do_restore_smart_tags/2

[altdsoy]

Hello 👋🏼, Is there a plan to merge that PR?

[altdsoy]

Little up.. I hope OP @pzingg and author @boydm you are all good...

[thbar]

I think we even got compilation failures at times (but not always), most likely linked to out upgrade to Elixir 1.15.

See:

• https://github.com/elixir-lang/elixir/issues/12913#issuecomment-1752008091
• https://github.com/etalab/transport-site/issues/3499

It would be nice to merge this PR for continued use of the library on Elixir 1.15+!

[thbar]

/cc @boydm @WalkerMills - unsure if this project is still maintained, and/or if you need extra people?