Class extended to a trait fail on invokespecial when mixed in.

[nicolasstucki]

class A {
  def foo: Int = 1
}

trait B extends A

abstract class D {
  def foo: Int
}

class C extends D with B

object Test {
  def main(args: Array[String]): Unit = {
    println(new C().foo)
  }
}

will fail with:

java.lang.VerifyError: Bad invokespecial instruction: current class isn't assignable to reference class.
Exception Details:
  Location:
    C.foo()I @1: invokespecial
  Reason:
    Error exists in the bytecode
  Bytecode:
    0x0000000: 2ab7 0013 ac                           

    at Test$.main(foo.scala:16)
    at Test.main(foo.scala)
    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 scala.reflect.internal.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:70)
    at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:31)
    at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:101)
    at scala.reflect.internal.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:70)
    at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:101)
    at scala.tools.nsc.CommonRunner$class.run(ObjectRunner.scala:22)
    at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:39)
    at scala.tools.nsc.CommonRunner$class.runAndCatch(ObjectRunner.scala:29)
    at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:39)
    at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:65)
    at scala.tools.nsc.MainGenericRunner.run$1(MainGenericRunner.scala:87)
    at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:98)
    at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:103)
    at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

[DarkDimius]

@nicolasstucki, this shouldn't compile at all.

in your example C has two superclasses - A and D.

[nicolasstucki]

@DarkDimius I was trying to reproduce the bug we looked at earlier and wasn't able. I got this while fuzzing the code a bit to try to reproduce it.