unhandled exception while running pickler

[peter-empen]

Compiler version

any starting with 3.3.1 (3.3.0 works fine)

Minimized code

You may reproduce the issue by git clone https://github.com/scala-graph/scala-graph.git and in SBT

project core
++3.3.0
compile // success
++3.3.4!
compile // failure

Output (click arrows to expand)

tree def

error when pickling tree def root: GraphTraversal.this.NodeT
error when pickling tree [A >: Nothing <: Any,
  CC >: Nothing <: GraphTraversal.this.TraverserMethods[A, CC]]() extends
  GraphTraversal.this.FluentProperties[TraverserMethods.this.CC]() {
  this: TraverserMethods.this.CC & GraphTraversal.this.Properties =>
  A
  +CC <: GraphTraversal.this.TraverserMethods[A, CC]
  def root: GraphTraversal.this.NodeT
  protected def nodeVisitor[U >: Nothing <: Any](f: A => U):
    GraphTraversal.this.NodeT => U
  protected def edgeVisitor[U >: Nothing <: Any](f: A => U):
    GraphTraversal.this.EdgeT => U
  final def withRoot(root: GraphTraversal.this.NodeT): TraverserMethods.this.CC
     =
    if this.root.eq(root) then this else 
      this.newTraverser.apply(root, this.parameters, this.subgraphNodes,
        this.subgraphEdges, this.ordering, this.maxWeight)
    ...(a lot more)

stack trace

  unhandled exception while running pickler on /home/peter/Graph4Scala/2.x/core/src/main/scala/scalax/collection/GraphTraversal.scala

  An unhandled exception was thrown in the compiler.
  Please file a crash report here:
  https://github.com/lampepfl/dotty/issues/new/choose
  For non-enriched exceptions, compile with -Yno-enrich-error-messages.

     while compiling: /home/peter/Graph4Scala/2.x/core/src/main/scala/scalax/collection/GraphTraversal.scala
        during phase: pickler
                mode: Mode(ImplicitsEnabled)
     library version: version 2.13.14
    compiler version: version 3.3.4
            settings: -Wunused List(imports, privates) -classpath /home/peter/Graph4Scala/2.x/core/.jvm/target/scala-3.3.4/classes:/home/peter/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala3-library_3/3.3.4/scala3-library_3-3.3.4.jar:/home/peter/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scalacheck/scalacheck_3/1.18.1/scalacheck_3-1.18.1.jar:/home/peter/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scala-lang/scala-library/2.13.14/scala-library-2.13.14.jar:/home/peter/.cache/coursier/v1/https/repo1.maven.org/maven2/org/scala-sbt/test-interface/1.0/test-interface-1.0.jar -d /home/peter/Graph4Scala/2.x/core/.jvm/target/scala-3.3.4/classes -deprecation true -feature true -language List(higherKinds)

[error] ## Exception when compiling 82 sources to /home/peter/Graph4Scala/2.x/core/.jvm/target/scala-3.3.4/classes
[error] java.lang.AssertionError: assertion failed: method root
[error] scala.runtime.Scala3RunTime$.assertFailed(Scala3RunTime.scala:8)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:327)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:580)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:372)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:372)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:606)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:336)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:582)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:372)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:372)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:606)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleDef(TreePickler.scala:336)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:582)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleStats$$anonfun$2(TreePickler.scala:372)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleStats(TreePickler.scala:372)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickleTree(TreePickler.scala:622)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickle$$anonfun$1(TreePickler.scala:816)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.tasty.TreePickler.pickle(TreePickler.scala:814)
[error] dotty.tools.dotc.transform.Pickler.run$$anonfun$1$$anonfun$1(Pickler.scala:90)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.transform.Pickler.run$$anonfun$1(Pickler.scala:84)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.transform.Pickler.run(Pickler.scala:83)
[error] dotty.tools.dotc.core.Phases$Phase.runOn$$anonfun$1(Phases.scala:336)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.immutable.List.foreach(List.scala:334)
[error] dotty.tools.dotc.core.Phases$Phase.runOn(Phases.scala:333)
[error] dotty.tools.dotc.transform.Pickler.runOn(Pickler.scala:151)
[error] dotty.tools.dotc.Run.runPhases$1$$anonfun$1(Run.scala:315)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:15)
[error] scala.runtime.function.JProcedure1.apply(JProcedure1.java:10)
[error] scala.collection.ArrayOps$.foreach$extension(ArrayOps.scala:1323)
[error] dotty.tools.dotc.Run.runPhases$1(Run.scala:308)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$1(Run.scala:349)
[error] dotty.tools.dotc.Run.compileUnits$$anonfun$adapted$1(Run.scala:358)
[error] dotty.tools.dotc.util.Stats$.maybeMonitored(Stats.scala:69)
[error] dotty.tools.dotc.Run.compileUnits(Run.scala:358)
[error] dotty.tools.dotc.Run.compileSources(Run.scala:261)
[error] dotty.tools.dotc.Run.compile(Run.scala:246)
[error] dotty.tools.dotc.Driver.doCompile(Driver.scala:37)
[error] dotty.tools.xsbt.CompilerBridgeDriver.run(CompilerBridgeDriver.java:141)
[error] dotty.tools.xsbt.CompilerBridge.run(CompilerBridge.java:22)
[error] sbt.internal.inc.AnalyzingCompiler.compile(AnalyzingCompiler.scala:91)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$7(MixedAnalyzingCompiler.scala:196)
[error] scala.runtime.java8.JFunction0$mcV$sp.apply(JFunction0$mcV$sp.java:23)
[error] sbt.internal.inc.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:251)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4(MixedAnalyzingCompiler.scala:186)
[error] sbt.internal.inc.MixedAnalyzingCompiler.$anonfun$compile$4$adapted(MixedAnalyzingCompiler.scala:166)
[error] sbt.internal.inc.JarUtils$.withPreviousJar(JarUtils.scala:241)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:166)
[error] sbt.internal.inc.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:214)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileInternal$1$adapted(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3(Incremental.scala:178)
[error] sbt.internal.inc.Incremental$.$anonfun$apply$3$adapted(Incremental.scala:176)
[error] sbt.internal.inc.Incremental$$anon$2.run(Incremental.scala:454)
[error] sbt.internal.inc.IncrementalCommon$CycleState.next(IncrementalCommon.scala:117)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:56)
[error] sbt.internal.inc.IncrementalCommon$$anon$1.next(IncrementalCommon.scala:52)
[error] sbt.internal.inc.IncrementalCommon.cycle(IncrementalCommon.scala:265)
[error] sbt.internal.inc.Incremental$.$anonfun$incrementalCompile$8(Incremental.scala:409)
[error] sbt.internal.inc.Incremental$.withClassfileManager(Incremental.scala:496)
[error] sbt.internal.inc.Incremental$.incrementalCompile(Incremental.scala:396)
[error] sbt.internal.inc.Incremental$.apply(Incremental.scala:170)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileInternal(IncrementalCompilerImpl.scala:534)
[error] sbt.internal.inc.IncrementalCompilerImpl.$anonfun$compileIncrementally$1(IncrementalCompilerImpl.scala:488)
[error] sbt.internal.inc.IncrementalCompilerImpl.handleCompilationError(IncrementalCompilerImpl.scala:332)
[error] sbt.internal.inc.IncrementalCompilerImpl.compileIncrementally(IncrementalCompilerImpl.scala:425)
[error] sbt.internal.inc.IncrementalCompilerImpl.compile(IncrementalCompilerImpl.scala:137)
[error] sbt.Defaults$.compileIncrementalTaskImpl(Defaults.scala:2427)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$2(Defaults.scala:2377)
[error] sbt.internal.server.BspCompileTask$.$anonfun$compute$1(BspCompileTask.scala:41)
[error] sbt.internal.io.Retry$.apply(Retry.scala:47)
[error] sbt.internal.io.Retry$.apply(Retry.scala:29)
[error] sbt.internal.io.Retry$.apply(Retry.scala:24)
[error] sbt.internal.server.BspCompileTask$.compute(BspCompileTask.scala:41)
[error] sbt.Defaults$.$anonfun$compileIncrementalTask$1(Defaults.scala:2375)
[error] scala.Function1.$anonfun$compose$1(Function1.scala:49)
[error] sbt.internal.util.$tilde$greater.$anonfun$$u2219$1(TypeFunctions.scala:63)
[error] sbt.std.Transform$$anon$4.work(Transform.scala:69)
[error] sbt.Execute.$anonfun$submit$2(Execute.scala:283)
[error] sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:24)
[error] sbt.Execute.work(Execute.scala:292)
[error] sbt.Execute.$anonfun$submit$1(Execute.scala:283)
[error] sbt.ConcurrentRestrictions$$anon$4.$anonfun$submitValid$1(ConcurrentRestrictions.scala:265)
[error] sbt.CompletionService$$anon$2.call(CompletionService.scala:65)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
[error] java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
[error] java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
[error] java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
[error] java.base/java.lang.Thread.run(Thread.java:829)

[peter-empen]

how would you get a list of PRs/commits that changed the pickler after 3.3.0 and were released in 3.3.1?

[KacperFKorban]

@peter-empen You can probably just look at the git history of Pickler.scala
But I think that it would be easier to try to minimize your crash into a self-contained example.

[peter-empen]

Hey Kacper, I was able to boil it down to the following:

trait GraphTraversal  {
  type NodeT

  protected trait Properties {
    def root: NodeT
  }

  abstract protected class TraverserMethods[A, +CC <: TraverserMethods[A, CC]]  { this: CC with Properties =>
    def root: NodeT
  }
}

[prolativ]

Trying to bisect that. The regression seems to have happened somewhere between 3.3.1-RC1-bin-20230215-006e2e4-NIGHTLY and 3.3.1-RC1-bin-20230216-2507577-NIGHTLY

[prolativ]

Bisected further with scala-cli project/scripts/bisect.scala -- --bootstrapped --releases 3.3.1-RC1-bin-20230215-006e2e4-NIGHTLY...3.3.1-RC1-bin-20230216-2507577-NIGHTLY compile /tmp/bisect/GraphTraversal.scala.
This points to c830ad2