AssertionError: duplicate attachment when calling method with default arguments in mutliple given parameter lists

[panacekcz]

minimized code

trait A
trait B
object O{
  def m(given x:A = null)(given y:B = null) = 1
  def n = m
}

Crash output (click arrow to expand)

exception occurred while typechecking given-default.scala
exception occurred while compiling given-default.scala
java.lang.AssertionError: assertion failed: duplicate attachment for key dotty.tools.dotc.util.Property$StickyKey@31c2affc while compiling given-default.scala
Exception in thread "main" java.lang.AssertionError: assertion failed: duplicate attachment for key dotty.tools.dotc.util.Property$StickyKey@31c2affc
	at dotty.DottyPredef$.assertFail(DottyPredef.scala:17)
	at dotty.tools.dotc.util.Attachment$Container.pushAttachment(Attachment.scala:118)
	at dotty.tools.dotc.ast.Trees$Tree.pushAttachment(Trees.scala:55)
	at dotty.tools.dotc.ast.Trees$Apply.setGivenApply(Trees.scala:443)
	at dotty.tools.dotc.typer.Typer.addImplicitArgs$2$$anonfun$2(Typer.scala:2765)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:2375)
	at dotty.tools.dotc.typer.Typer.addImplicitArgs$4(Typer.scala:2770)
	at dotty.tools.dotc.typer.Typer.adaptNoArgsImplicitMethod$2(Typer.scala:2787)
	at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:2957)
	at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:3185)
	at dotty.tools.dotc.typer.Typer.op$3(Typer.scala:2578)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:2579)
	at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2247)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2256)
	at dotty.tools.dotc.typer.Typer.addImplicitArgs$2$$anonfun$2(Typer.scala:2767)
	at dotty.tools.dotc.typer.Typer.tryEither(Typer.scala:2375)
	at dotty.tools.dotc.typer.Typer.addImplicitArgs$4(Typer.scala:2770)
	at dotty.tools.dotc.typer.Typer.adaptNoArgsImplicitMethod$2(Typer.scala:2787)
	at dotty.tools.dotc.typer.Typer.adaptNoArgs$1(Typer.scala:2957)
	at dotty.tools.dotc.typer.Typer.adapt1(Typer.scala:3185)
	at dotty.tools.dotc.typer.Typer.op$3(Typer.scala:2578)
	at dotty.tools.dotc.typer.Typer.adapt(Typer.scala:2579)
	at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2247)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2256)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2259)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr$$anonfun$1(Namer.scala:1267)
	at dotty.tools.dotc.typer.Namer.typedAhead(Namer.scala:1257)
	at dotty.tools.dotc.typer.Namer.typedAheadExpr(Namer.scala:1267)
	at dotty.tools.dotc.typer.Namer.rhsType$2(Namer.scala:1401)
	at dotty.tools.dotc.typer.Namer.cookedRhsType$1(Namer.scala:1412)
	at dotty.tools.dotc.typer.Namer.lhsType$1(Namer.scala:1413)
	at dotty.tools.dotc.typer.Namer.inferredType$1(Namer.scala:1424)
	at dotty.tools.dotc.typer.Namer.valOrDefDefSig(Namer.scala:1432)
	at dotty.tools.dotc.typer.Namer.defDefSig(Namer.scala:1504)
	at dotty.tools.dotc.typer.Namer$Completer.typeSig(Namer.scala:815)
	at dotty.tools.dotc.typer.Namer$Completer.completeInCreationContext(Namer.scala:935)
	at dotty.tools.dotc.typer.Namer$Completer.complete(Namer.scala:843)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.completeFrom(SymDenotations.scala:258)
	at dotty.tools.dotc.core.Denotations$Denotation.completeInfo$1(Denotations.scala:185)
	at dotty.tools.dotc.core.Denotations$Denotation.info(Denotations.scala:187)
	at dotty.tools.dotc.core.SymDenotations$SymDenotation.ensureCompleted(SymDenotations.scala:398)
	at dotty.tools.dotc.typer.Typer.retrieveSym(Typer.scala:2103)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2128)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2208)
	at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2247)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2256)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2259)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2281)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2325)
	at dotty.tools.dotc.typer.Typer.typedClassDef(Typer.scala:1812)
	at dotty.tools.dotc.typer.Typer.typedNamed$1(Typer.scala:2141)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2208)
	at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2247)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2256)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2259)
	at dotty.tools.dotc.typer.Typer.traverse$1(Typer.scala:2281)
	at dotty.tools.dotc.typer.Typer.typedStats(Typer.scala:2325)
	at dotty.tools.dotc.typer.Typer.typedPackageDef(Typer.scala:1938)
	at dotty.tools.dotc.typer.Typer.typedUnnamed$1(Typer.scala:2182)
	at dotty.tools.dotc.typer.Typer.typedUnadapted(Typer.scala:2209)
	at dotty.tools.dotc.typer.Typer.op$1(Typer.scala:2247)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2256)
	at dotty.tools.dotc.typer.Typer.typed(Typer.scala:2259)
	at dotty.tools.dotc.typer.Typer.typedExpr(Typer.scala:2367)
	at dotty.tools.dotc.typer.FrontEnd.liftedTree1$2(FrontEnd.scala:78)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck$$anonfun$1(FrontEnd.scala:83)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.typer.FrontEnd.monitor(FrontEnd.scala:42)
	at dotty.tools.dotc.typer.FrontEnd.typeCheck(FrontEnd.scala:84)
	at dotty.tools.dotc.typer.FrontEnd.runOn$$anonfun$3(FrontEnd.scala:114)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:305)
	at dotty.tools.dotc.typer.FrontEnd.runOn(FrontEnd.scala:114)
	at dotty.tools.dotc.Run.runPhases$4$$anonfun$4(Run.scala:167)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at dotty.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
	at dotty.tools.dotc.Run.runPhases$5(Run.scala:177)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:185)
	at dotty.runtime.function.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:12)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:64)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:192)
	at dotty.tools.dotc.Run.compileSources(Run.scala:129)
	at dotty.tools.dotc.Run.compile(Run.scala:112)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:36)
	at dotty.tools.dotc.Driver.process(Driver.scala:189)
	at dotty.tools.dotc.Driver.process(Driver.scala:158)
	at dotty.tools.dotc.Driver.process(Driver.scala:170)
	at dotty.tools.dotc.Driver.main(Driver.scala:197)
	at dotty.tools.dotc.Main.main(Main.scala)