Invalid "never used" warnings with Scala 2.13.9

[gaeljw]

Reproduction steps

Scala version: 2.13.9

Upgrading from Scala 2.13.8 to 2.13.9 leads to code incorrectly identified as "non used".

I didn't set up a reproduction repo yet but could provide one later if needed.

My current reproduction code is in test scope:

trait SomeTrait extends Matchers {

  var something: SomeCaseClass = _

  def foo() = {
    something.x mustEqual true
  }

}

And the error message (warnings raised as errors):

[error] ....scala:16:7: parameter value something_= in variable something is never used
[error]   var something: SomeCaseClass = _

Problem

This variable is definitely used, there's no reason to see it as not used.

Also the error message is a bit weird with this appended underscore, isn't it? 🤔

[He-Pin]

#12646

[gaeljw]

Thanks @He-Pin , I hadn't see the duplicate!