purge erlang modules on recompilation

[sasa1977]

The issue is described here

tl;dr of it is that a situation can happen that a mix task works with an older version of the module written in Erlang. This can occur if some previous task, (e.g. Phoenix compiler) loaded the module before the Erlang compiler recompiled the code. The agreed solution is to make the Erlang compiler purge the module if it is about to be compiled.

[whatyouhide]

Maybe we can call this (and above) fun instead of fn? Just not to mess with Elixir's keywords 😄

[lexmag]

fun is an Erlang keyword.
I suggest my_fun as we usually do my_ prefixing.

[sasa1977]

This is Erlang code, so your reasoning is in fact why I called it fn :-)

[whatyouhide]

Oh ahah, right 😄 Let's go with my_fun or my_fn then :)

[whatyouhide]

Other extreme nitpick: can we use capital letters in the commit message as well? (Purge Erlang modules on recompilation)

[sasa1977]

Sure, once you're done reviewing, I'll change the history and force push.

[whatyouhide]

And nitpicks apart, great job @sasa1977 💟

[josevalim]

This test could be easier if you simply define an Elixir module before calling Compile.Erlang. Something like:

defmodule :purge_test do
  def version, do: :v1
end

This way you don't need to write to disk and compile multiple times.

[sasa1977]

OK, I think I addressed it all, squashed and force pushed.

[josevalim]

Merged and backported to v1.2 (new release coming this or next week).