java.lang.AssertionError: assertion failed: orphan parameter reference: TermParamRef(service)

[kubukoz]

Compiler version

3.7.0-RC1

Minimized code

//> using scala 3.7.0-RC1

trait Wrapper {
  type Member
}

object Wrapper {

  type Aux[M] =
    Wrapper {
      type Member = M
    }

}

// note: the `private` and `private val` are probably not necessary
final case class Demo[M] private (
    private val service: Wrapper.Aux[M],
    private val endpoints: Vector[service.Member]
)

Output (click arrow to expand)

�[90mCompiling project (Scala 3.7.0-RC1, JVM (21))�[0m
�[90mError compiling project (Scala 3.7.0-RC1, JVM (21))�[0m
Error: java.lang.AssertionError: assertion failed: orphan parameter reference: TermParamRef(service)
	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType(TreePickler.scala:318)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleType(TreePickler.scala:183)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType(TreePickler.scala:239)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleType(TreePickler.scala:183)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType$$anonfun$2(TreePickler.scala:204)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType(TreePickler.scala:204)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleType(TreePickler.scala:183)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:716)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTpt(TreePickler.scala:352)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:382)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:647)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree$$anonfun$6(TreePickler.scala:571)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:571)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTreeUnlessEmpty(TreePickler.scala:356)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:390)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:662)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:423)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:423)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:698)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:381)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:664)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:423)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:423)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:714)
	at dotty.tools.dotc.core.tasty.TreePickler.pickle$$anonfun$1(TreePickler.scala:938)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickle(TreePickler.scala:936)
	at dotty.tools.dotc.transform.Pickler.run$$anonfun$1$$anonfun$1(Pickler.scala:306)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.transform.Pickler.run$$anonfun$1(Pickler.scala:279)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.transform.Pickler.run(Pickler.scala:278)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:383)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:376)
	at dotty.tools.dotc.transform.Pickler.runPhase$1(Pickler.scala:392)
	at dotty.tools.dotc.transform.Pickler.runOn(Pickler.scala:398)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:367)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1324)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:360)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$2(Run.scala:407)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$adapted$1(Run.scala:407)
	at scala.Function0.apply$mcV$sp(Function0.scala:42)
	at dotty.tools.dotc.Run.showProgress(Run.scala:469)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:407)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:419)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:419)
	at dotty.tools.dotc.Run.compileSources(Run.scala:306)
	at dotty.tools.dotc.Run.compile(Run.scala:291)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.compileSources$1(BloopHighLevelCompiler.scala:148)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$9(BloopHighLevelCompiler.scala:181)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$1(BloopHighLevelCompiler.scala:73)
	at bloop.tracing.NoopTracer$.trace(BraveTracer.scala:53)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.timed$1(BloopHighLevelCompiler.scala:72)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$8(BloopHighLevelCompiler.scala:181)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at monix.eval.internal.TaskRunLoop$.startFull(TaskRunLoop.scala:81)
	at monix.eval.internal.TaskRestartCallback.syncOnSuccess(TaskRestartCallback.scala:101)
	at monix.eval.internal.TaskRestartCallback.onSuccess(TaskRestartCallback.scala:74)
	at monix.eval.internal.TaskExecuteOn$AsyncRegister$$anon$1.run(TaskExecuteOn.scala:71)
	at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1423)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)

Error: Unexpected error when compiling tmp_a73cf1c06b: java.lang.AssertionError: assertion failed: orphan parameter reference: TermParamRef(service)
	at scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType(TreePickler.scala:318)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleType(TreePickler.scala:183)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType(TreePickler.scala:239)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleType(TreePickler.scala:183)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType$$anonfun$2(TreePickler.scala:204)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleNewType(TreePickler.scala:204)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleType(TreePickler.scala:183)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:716)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTpt(TreePickler.scala:352)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:382)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:647)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree$$anonfun$6(TreePickler.scala:571)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:571)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTreeUnlessEmpty(TreePickler.scala:356)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:390)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:662)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:423)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:423)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:698)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:381)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:664)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:423)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:423)
	at dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:714)
	at dotty.tools.dotc.core.tasty.TreePickler.pickle$$anonfun$1(TreePickler.scala:938)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.tasty.TreePickler.pickle(TreePickler.scala:936)
	at dotty.tools.dotc.transform.Pickler.run$$anonfun$1$$anonfun$1(Pickler.scala:306)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.transform.Pickler.run$$anonfun$1(Pickler.scala:279)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.transform.Pickler.run(Pickler.scala:278)
	at dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:383)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.immutable.List.foreach(List.scala:334)
	at dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:376)
	at dotty.tools.dotc.transform.Pickler.runPhase$1(Pickler.scala:392)
	at dotty.tools.dotc.transform.Pickler.runOn(Pickler.scala:398)
	at dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:367)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
	at scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
	at scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1324)
	at dotty.tools.dotc.Run.runPhases$1(Run.scala:360)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$2(Run.scala:407)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1$$anonfun$adapted$1(Run.scala:407)
	at scala.Function0.apply$mcV$sp(Function0.scala:42)
	at dotty.tools.dotc.Run.showProgress(Run.scala:469)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:407)
	at dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:419)
	at dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
	at dotty.tools.dotc.Run.compileUnits(Run.scala:419)
	at dotty.tools.dotc.Run.compileSources(Run.scala:306)
	at dotty.tools.dotc.Run.compile(Run.scala:291)
	at dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
	at dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
	at dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
	at sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.compileSources$1(BloopHighLevelCompiler.scala:148)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$9(BloopHighLevelCompiler.scala:181)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$1(BloopHighLevelCompiler.scala:73)
	at bloop.tracing.NoopTracer$.trace(BraveTracer.scala:53)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.timed$1(BloopHighLevelCompiler.scala:72)
	at sbt.internal.inc.bloop.internal.BloopHighLevelCompiler.$anonfun$compile$8(BloopHighLevelCompiler.scala:181)
	at scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
	at monix.eval.internal.TaskRunLoop$.startFull(TaskRunLoop.scala:81)
	at monix.eval.internal.TaskRestartCallback.syncOnSuccess(TaskRestartCallback.scala:101)
	at monix.eval.internal.TaskRestartCallback.onSuccess(TaskRestartCallback.scala:74)
	at monix.eval.internal.TaskExecuteOn$AsyncRegister$$anon$1.run(TaskExecuteOn.scala:71)
	at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1423)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)

Compilation failed

As a workaround, one can simply use M instead of service.Member in the Vector type parameter.

[kubukoz]

This is minimized from a higher-kinded version - worth checking that one too, after a fix:

//> using scala 3.7.0-RC1

trait Servo[Alg[_[_]]] {

  type Operation[I]
}

object Servo {

  type Aux[Alg[_[_]], Op[_]] =
    Servo[Alg] {
      type Operation[I] = Op[I]
    }

}

trait MyEndpoint[Op[_]]

final case class BSPBuilder2[Alg[_[_]], Op[_]] private (
    private val service: Servo.Aux[Alg, Op],
    private val endpoints: Vector[MyEndpoint[service.Operation]]
)

[odersky]

Thanks for the minimizations! That helped a lot pinpointing the problem.