compiler crash in GenBCode referring to a class that extends an annotation

[scabug]

tail  sandbox/{Named,NamedImpl}.java sandbox/test.scala
==> sandbox/Named.java <==
package bug;

public @interface Named {}

==> sandbox/NamedImpl.java <==
import bug.Named;
import java.io.Serializable;
import java.lang.annotation.Annotation;

public class NamedImpl implements Named {

    public Class<? extends Annotation> annotationType() {
        return null;
    }
}

==> sandbox/test.scala <==
class C {
  new bug.NamedImpl
}
ticket/9387 /code/scala javac -d . sandbox/Named.java sandbox/NamedImpl.java && qscalac sandbox/test.scala
java.lang.AssertionError: assertion failed: Invalid interfaces in Lbug/NamedImpl;: List(Lbug/Named;)
	at scala.Predef$.assert(Predef.scala:165)
	at scala.tools.nsc.backend.jvm.BTypes$ClassBType.checkInfoConsistency(BTypes.scala:850)
	at scala.tools.nsc.backend.jvm.BTypes$ClassBType.info_$eq(BTypes.scala:827)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.scala$tools$nsc$backend$jvm$BTypesFromSymbols$$setClassInfo(BTypesFromSymbols.scala:344)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols$$anonfun$classBTypeFromSymbol$4.apply(BTypesFromSymbols.scala:120)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols$$anonfun$classBTypeFromSymbol$4.apply(BTypesFromSymbols.scala:112)
	at scala.collection.MapLike$class.getOrElse(MapLike.scala:128)
	at scala.collection.concurrent.TrieMap.getOrElse(TrieMap.scala:633)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.classBTypeFromSymbol(BTypesFromSymbols.scala:112)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols$$anonfun$primitiveOrClassToBType$1$2.apply(BTypesFromSymbols.scala:153)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols$$anonfun$primitiveOrClassToBType$1$2.apply(BTypesFromSymbols.scala:153)
	at scala.collection.MapLike$class.getOrElse(MapLike.scala:128)
	at scala.collection.AbstractMap.getOrElse(Map.scala:59)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.primitiveOrClassToBType$1(BTypesFromSymbols.scala:153)
	at scala.tools.nsc.backend.jvm.BTypesFromSymbols.typeToBType(BTypesFromSymbols.scala:168)
	at scala.tools.nsc.backend.jvm.BCodeHelpers$BCInnerClassGen$class.toTypeKind(BCodeHelpers.scala:355)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.toTypeKind(BCodeSkelBuilder.scala:50)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.tpeTK(BCodeSkelBuilder.scala:85)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genApply(BCodeBodyBuilder.scala:599)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:312)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genStat(BCodeBodyBuilder.scala:89)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder$$anonfun$genBlock$1.apply(BCodeBodyBuilder.scala:809)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder$$anonfun$genBlock$1.apply(BCodeBodyBuilder.scala:809)
	at scala.collection.immutable.List.foreach(List.scala:381)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genBlock(BCodeBodyBuilder.scala:809)
	at scala.tools.nsc.backend.jvm.BCodeBodyBuilder$PlainBodyBuilder.genLoad(BCodeBodyBuilder.scala:373)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.emitNormalMethodBody$1(BCodeSkelBuilder.scala:621)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.genDefDef(BCodeSkelBuilder.scala:655)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen(BCodeSkelBuilder.scala:525)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder$$anonfun$gen$1.apply(BCodeSkelBuilder.scala:527)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder$$anonfun$gen$1.apply(BCodeSkelBuilder.scala:527)
	at scala.collection.immutable.List.foreach(List.scala:381)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.gen(BCodeSkelBuilder.scala:527)
	at scala.tools.nsc.backend.jvm.BCodeSkelBuilder$PlainSkelBuilder.genPlainClass(BCodeSkelBuilder.scala:125)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase$Worker1.visit(GenBCode.scala:183)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase$Worker1$$anonfun$run$1.apply$mcV$sp(GenBCode.scala:137)
	at scala.tools.nsc.Global$GlobalPhase.withCurrentUnit(Global.scala:431)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase$Worker1.run(GenBCode.scala:137)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase.buildAndSendToDisk(GenBCode.scala:355)
	at scala.tools.nsc.backend.jvm.GenBCode$BCodePhase.run(GenBCode.scala:324)
	at scala.tools.nsc.Global$Run.compileUnitsInternal(Global.scala:1504)
	at scala.tools.nsc.Global$Run.compileUnits(Global.scala:1489)
	at scala.tools.nsc.Global$Run.compileSources(Global.scala:1484)
	at scala.tools.nsc.Global$Run.compile(Global.scala:1585)
	at scala.tools.nsc.Driver.doCompile(Driver.scala:35)
	at scala.tools.nsc.MainClass.doCompile(Main.scala:24)
	at scala.tools.nsc.Driver.process(Driver.scala:55)
	at scala.tools.nsc.Driver.main(Driver.scala:68)
	at scala.tools.nsc.Main.main(Main.scala)
error: Error while emitting test.scala
assertion failed: Invalid interfaces in Lbug/NamedImpl;: List(Lbug/Named;)
one error found

As seen in the community build: https://typesafe.slack.com/files/adriaan/F07FZV3PT/genbcode_crasher_in_play-core__community_build_.sh

/cc @adriaanm @SethTisue @lrytz

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-9393?orig=1
Reporter: @retronym
Affected Versions: 2.12.0-M1

[scabug]

@retronym said:
Disabling the assertions as the first step: scala/scala#4621

[scabug]

@retronym said:
We're going to recut 2.12.0-M2 with the assertions disabled.

[scabug]

@lrytz said:
The problem here is that the Scala classfile parser doesn't use the real classfile flags for java annotations, but makes them look like scala classes: https://github.com/scala/scala/blob/2.11.x/src/reflect/scala/reflect/internal/ClassfileConstants.scala#L345

In reality, a classfile for a java annotation has the flags ACC_ANNOTATION, ACC_ABSTRACT and ACC_INTERFACE. They are all skipped when creating the symbol.

We also have to see what the java source parser does to java annotations in terms of flags.

[scabug]

@lrytz said (edited on Jan 4, 2016 1:03:37 PM UTC):
scala/scala#4638