mix compile --warning-as-errors ignored when called from umbrella root

[stefanluptak]

When having a call to a non-existing function, doing mix compile --warnings-as-errors from umbrella root, it doesn't fail, but it should.

When doing mix compile --warnings-as-errors from one of the apps inside the umbrella, everything works as expected.

This probably changed with Elixir 1.19. Previously it worked.

I made a repo to reproduce this issue. Everything needed is (I hope) in the readme there. https://github.com/stefanluptak/compile_warnings

[jeremyowensboggs]

We are also seeing the same thing with mix compile --force from the umbrella root using 1.19

mix compile and mix compile --force behave exactly the same way.

[Ch4s3]

Should this @switches line include warnings-as-errors?

[Ch4s3]

Testing this locally it looks like 1.19 on are just doing protocol reconsolidation on --force.

[Ch4s3]

I thing the change here is related.

      if stale != [] do
        Mix.Utils.compiling_n(length(stale), :ex)
      end

[Ch4s3]

small fix for the warnings-as-errors flag #14860

[Ch4s3]

Thanks for the quick turn around @josevalim !