Whitelisting scala.sys.BooleanProp crashes the compiler.

[nicolasstucki]

If scala/sys/BooleanProp.scala is added to the whitelist scala-collections.whitelist the with

dotty.tools.dotc.reporting.diagnostic.messages$Error: method clear is already defined as getter clear: ()scala.runtime.BoxedUnit

ConstantImpl is implementing clear, enable, disable, toggle and fails on each one.

class ConstantImpl(val key: String, val value: Boolean) extends BooleanProp {
    ...
    val clear, enable, disable, toggle = ()
    ...
  }

where

trait BooleanProp extends Prop[Boolean] {
  def enable(): Unit
  def disable(): Unit
  def toggle(): Unit
}

If the code in ConstantImpl is replaced with defs for each member it fixes the issue.