Assertion failed: Invalid interfaces

[scabug]

Reproduction case:

public class A {
  public static class Inner {
    protected static interface InnerInterface { }
  }
}
public class B {
  public static class Inner extends A.Inner  {
    private class ProblemClass implements InnerInterface { }
  }
}

object Main {
  def main(args: Array[String]): Unit = {
    val b = new B();
  }
}

When I compile with ./sbt ++2.12.1, I get:

java.lang.AssertionError: assertion failed: Invalid interfaces in LB$Inner$ProblemClass;: List(Ljava/lang/Object;)
	at scala.tools.nsc.backend.jvm.BTypes$ClassBType.checkInfoConsistency(BTypes.scala:893)
	at scala.tools.nsc.backend.jvm.BTypes$ClassBType.info_$eq(BTypes.scala:868)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.setClassInfo(BTypesFromSymbols.scala:446)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.$anonfun$classBTypeFromSymbol$5(BTypesFromSymbols.scala:126)
	at scala.collection.MapLike.getOrElse(MapLike.scala:128)
	at scala.collection.MapLike.getOrElse$(MapLike.scala:126)
	at scala.collection.concurrent.TrieMap.getOrElse(TrieMap.scala:631)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.classBTypeFromSymbol(BTypesFromSymbols.scala:118)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.$anonfun$setClassInfo$17(BTypesFromSymbols.scala:440)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.setClassInfo(BTypesFromSymbols.scala:440)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.$anonfun$classBTypeFromSymbol$5(BTypesFromSymbols.scala:126)
	at scala.collection.MapLike.getOrElse(MapLike.scala:128)
	at scala.collection.MapLike.getOrElse$(MapLike.scala:126)
	at scala.collection.concurrent.TrieMap.getOrElse(TrieMap.scala:631)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.classBTypeFromSymbol(BTypesFromSymbols.scala:118)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.$anonfun$setClassInfo$17(BTypesFromSymbols.scala:440)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.setClassInfo(BTypesFromSymbols.scala:440)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.$anonfun$classBTypeFromSymbol$5(BTypesFromSymbols.scala:126)
	at scala.collection.MapLike.getOrElse(MapLike.scala:128)
	at scala.collection.MapLike.getOrElse$(MapLike.scala:126)
	at scala.collection.concurrent.TrieMap.getOrElse(TrieMap.scala:631)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.classBTypeFromSymbol(BTypesFromSymbols.scala:118)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.$anonfun$typeToBType$1(BTypesFromSymbols.scala:177)
	at scala.collection.MapLike.getOrElse(MapLike.scala:128)
	at scala.collection.MapLike.getOrElse$(MapLike.scala:126)
	at scala.collection.AbstractMap.getOrElse(Map.scala:59)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.primitiveOrClassToBType$1(BTypesFromSymbols.scala:177)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.typeToBType(BTypesFromSymbols.scala:192)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.symInfoTK(BCodeSkelBuilder.scala:77)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder$locals$.makeLocal(BCodeSkelBuilder.scala:366)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder$locals$.$anonfun$getOrMakeLocal$1(BCodeSkelBuilder.scala:371)
	at scala.collection.MapLike.getOrElse(MapLike.scala:128)
	at scala.collection.MapLike.getOrElse$(MapLike.scala:126)
	at scala.collection.AbstractMap.getOrElse(Map.scala:59)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder$locals$.getOrMakeLocal(BCodeSkelBuilder.scala:371)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:270)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genStat(BCodeBodyBuilder.scala:82)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.$anonfun$genBlock$1(BCodeBodyBuilder.scala:812)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genBlock(BCodeBodyBuilder.scala:812)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:364)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.emitNormalMethodBody$1(BCodeSkelBuilder.scala:603)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.genDefDef(BCodeSkelBuilder.scala:635)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen(BCodeSkelBuilder.scala:509)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.$anonfun$gen$7(BCodeSkelBuilder.scala:511)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen(BCodeSkelBuilder.scala:511)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.genPlainClass(BCodeSkelBuilder.scala:113)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase$Worker1.visit(GenBCode.scala:190)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase$Worker1.$anonfun$run$1(GenBCode.scala:139)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase$Worker1.run(GenBCode.scala:139)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase.buildAndSendToDisk(GenBCode.scala:381)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase.run(GenBCode.scala:350)
	at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1418)
	at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1403)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:1398)
	at scala.tools.nsc.Global$Run.compile(Global.scala:1492)
	at xsbt.CachedCompiler0.run(CompilerInterface.scala:116)
	at xsbt.CachedCompiler0.run(CompilerInterface.scala:95)
	at xsbt.CompilerInterface.run(CompilerInterface.scala:26)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at sbt.compiler.AnalyzingCompiler.call(AnalyzingCompiler.scala:101)
	at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:47)
	at sbt.compiler.AnalyzingCompiler.compile(AnalyzingCompiler.scala:41)
	at sbt.compiler.MixedAnalyzingCompiler$$anonfun$compileScala$1$1.apply$mcV$sp(MixedAnalyzingCompiler.scala:51)
	at sbt.compiler.MixedAnalyzingCompiler$$anonfun$compileScala$1$1.apply(MixedAnalyzingCompiler.scala:51)
	at sbt.compiler.MixedAnalyzingCompiler$$anonfun$compileScala$1$1.apply(MixedAnalyzingCompiler.scala:51)
	at sbt.compiler.MixedAnalyzingCompiler.timed(MixedAnalyzingCompiler.scala:75)
	at sbt.compiler.MixedAnalyzingCompiler.compileScala$1(MixedAnalyzingCompiler.scala:50)
	at sbt.compiler.MixedAnalyzingCompiler.compile(MixedAnalyzingCompiler.scala:65)
	at sbt.compiler.IC$$anonfun$compileInternal$1.apply(IncrementalCompiler.scala:160)
	at sbt.compiler.IC$$anonfun$compileInternal$1.apply(IncrementalCompiler.scala:160)
	at sbt.inc.IncrementalCompile$$anonfun$doCompile$1.apply(Compile.scala:66)
	at sbt.inc.IncrementalCompile$$anonfun$doCompile$1.apply(Compile.scala:64)
	at sbt.inc.IncrementalCommon.cycle(IncrementalCommon.scala:31)
	at sbt.inc.Incremental$$anonfun$1.apply(Incremental.scala:62)
	at sbt.inc.Incremental$$anonfun$1.apply(Incremental.scala:61)
	at sbt.inc.Incremental$.manageClassfiles(Incremental.scala:89)
	at sbt.inc.Incremental$.compile(Incremental.scala:61)
	at sbt.inc.IncrementalCompile$.apply(Compile.scala:54)
	at sbt.compiler.IC$.compileInternal(IncrementalCompiler.scala:160)
	at sbt.compiler.IC$.incrementalCompile(IncrementalCompiler.scala:138)
	at sbt.Compiler$.compile(Compiler.scala:128)
	at sbt.Compiler$.compile(Compiler.scala:114)
	at sbt.Defaults$.sbt$Defaults$$compileIncrementalTaskImpl(Defaults.scala:829)
	at sbt.Defaults$$anonfun$compileIncrementalTask$1.apply(Defaults.scala:820)
	at sbt.Defaults$$anonfun$compileIncrementalTask$1.apply(Defaults.scala:818)
	at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
	at sbt.$tilde$greater$$anonfun$$u2219$1.apply(TypeFunctions.scala:40)
	at sbt.std.Transform$$anon$4.work(System.scala:63)
	at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:226)
	at sbt.Execute$$anonfun$submit$1$$anonfun$apply$1.apply(Execute.scala:226)
	at sbt.ErrorHandling$.wideConvert(ErrorHandling.scala:17)
	at sbt.Execute.work(Execute.scala:235)
	at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:226)
	at sbt.Execute$$anonfun$submit$1.apply(Execute.scala:226)
	at sbt.ConcurrentRestrictions$$anon$4$$anonfun$1.apply(ConcurrentRestrictions.scala:159)
	at sbt.CompletionService$$anon$2.call(CompletionService.scala:28)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
[error] Error while emitting Main.scala
[error] assertion failed: Invalid interfaces in LB$Inner$ProblemClass;: List(Ljava/lang/Object;)
[error] one error found
[error] (compile:compileIncremental) Compilation failed

This compiles fine on 2.11.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-10107?orig=1
Reporter: Jillian Crossley (jillianc)
Affected Versions: 2.12.1
See #9111
Attachments:

• jillianc.zip (created on Dec 14, 2016 8:28:55 PM UTC, 1102825 bytes)

[scabug]

@lrytz said:
Will take a look. Note that the crash is only in mixed compilation. If the Java sources are compiled first, and only the Scala source file is passed to scalac, there's no crash.

[scabug]

@lrytz said:
As a workaround, change

private class ProblemClass implements InnerInterface { }

to

private class ProblemClass implements A.Inner.InnerInterface { }

[scabug]

@lrytz said:
This is basically another re-incarnation / a duplicate of #9111.

Changing the example a little:

A.java

public class A {
  public static class AInner {
    public static interface InnerInterface { }
  }
}

B.java

public class B {
  public static class BInner extends A.AInner  {
    public class ProblemClass implements InnerInterface { }
  }
}

Test.scala

object Main {
  def main(args: Array[String]): Unit = {
    // new B() // this still causes the crash reported in this ticket
    val bi = new B.BInner
    new bi.ProblemClass()
  }
}

The above doesn't compile (in mixed compilation), neither on 2.11, nor on 2.12:

$ scalac11 A.java B.java Test.scala
B.java:3: error: not found: type InnerInterface
    public class ProblemClass implements InnerInterface { }
                                         ^
one error found

This is due to the way the Scala compiler interprets Java static member classes, see #9111.

When the Scala code does new B() instead, it crashes in the backend. The reason is that the new backend causes some more types to be completed eagerly, something that has lead to other issues already and we should work on. But we have a workaround for #9111 in the backend, and I hope it can be extended to this bug. Will check tomorrow.

[scabug]

Jillian Crossley (jillianc) said:
That workaround works, thanks!

[scabug]

@lrytz said:
scala/scala#5606