Warnings are only reported when the module is compiled

[ajhager]

This isn't actually a bug, but a feature. The problem is that a module that has only warnings will compile correctly and so never show warnings after the first elm-make. The Main module seems to always be recompiled, but others don't.

If it weren't "elm-make --warn" but "elm-make --lint" it would make sense perhaps to force all code outside of elm-stuff to recompile so that warnings are always reported.

[tcoopman]

I've just found this out too, so just some info if someone else runs into this
I was running elm-reactorand I didn't get any warnings about unused imports when I compiled with elm-make --warn. Probably because elm-reactor had compiled the module already.

When I stopped elm-reactor and made a change to a file, then I got warnings.

[evancz]

Tracking from meta issue #98