t7933.scala: Exception while typechecking

[DarkDimius]

[info] compiling /Users/dark/workspace/dotty/tests/partest-generated/run/t7933.scala
[info] options: -pagewidth 160 -Yno-deep-subtypes -Yno-double-bindings -Ycheck:tailrec,resolveSuper,mixin,restoreScopes -d ./tests/partest-generated/run/t7933-run.obj
[info] failure while taking result signture of => StandardScalaSettings.this.BooleanSetting: StandardScalaSettings.this.BooleanSetting
[info] cannot take signature of => StandardScalaSettings.this.BooleanSetting
[info] findMember exception for => scala.tools.nsc.Settings(tools.nsc.interpreter.IMain#settings) member usejavacp
[info] assertion failure for => scala.tools.nsc.Settings(tools.nsc.interpreter.IMain#settings) <:< ?{ usejavacp: ? }, frozen = false
[info] => scala.tools.nsc.Settings(tools.nsc.interpreter.IMain#settings) is a class dotty.tools.dotc.core.Types$TermRefWithSignature
[info] ?{ usejavacp: ? } is a class dotty.tools.dotc.typer.ProtoTypes$CachedSelectionProto
[info] exception occurred while typechecking /Users/dark/workspace/dotty/tests/partest-generated/run/t7933.scala
[info] exception occurred while compiling /Users/dark/workspace/dotty/tests/partest-generated/run/t7933.scala