warn-unused-patvars.scala:7: warning: private val x in trait Boundings is never used
  private val x = 42                      // warn, sanity check
              ^
warn-unused-patvars.scala:26: warning: local val x in method v is never used
    val D(x) = d                          // warn, fixme
         ^
warn-unused-patvars.scala:30: warning: local val x in method w is never used
    val D(x @ _) = d                      // warn, fixme (valdef pos is different)
         ^
error: No warnings can be incurred under -Xfatal-warnings.
three warnings found
one error found