import compilation error upgrading from play 2.5.14 to play 2.6.7

[Gary Malouf]

I've scoured the migration docs and examples trying to find an explanation, but have failed thus far.  We have a few form helper files we generate internally in a parent play project that get used across multiple sub-projects that are not compiling under play 2.6.7.

Example:

checkboxFormHelper.scala.html

@(elements: helper.FieldElements)

<div class="form-group checkbox-group @if(elements.hasErrors) {error}">
    @elements.input
    <label for="@elements.id" class="checkbox">@elements.label</label>
    <span class="errors">@elements.errors.mkString(", ")</span>
</div>

Compilation Error:

[error] /Users/gary/coriander/app/com/offerlogic/coriander/infrastructure/display/checkboxFormHelper.scala.html:1: Unused import

[error] @(elements: helper.FieldElements)

This error is repeated for other template files - not really sure what changed to cause this.

[Gary Malouf]

Removing the scalac option '-Xfatal-warnings’ lets compilation pass, but I’m still unclear why these are now considered unused imports when that was not an issue in play 2.5

[Gary Malouf]

From further research - this issue appears with scala 2.12.2 (and onward).  Disabling -Xlint is what finally gets rid of the errors - though I feel pretty icky about it.