NoSuchMethodError when calling implementation trait method from Java

[scabug]

I ran into a NoSuchMethodError when trying to implement my own "implementation trait" code, patterned after TraversableLike.

The following Java and Scala code compiles without errors:

ScalaTest.scala:

trait MyTrait[T, This <: MyTrait[T, This]] {
  def x: This

  def myVal(): This = x

  def hello() = {System.out.println("HELLO")}
}

class MyClass[T]() extends MyTrait[T, MyClass[T]] {
  def x : MyClass[T] = new MyClass
}

object ScalaTest {
    def main(args: Array[String]) {
       val x : MyClass[Int] = new MyClass[Int]
       x.hello()
       x.myVal()
    }
}

JavaTest.java:

public class JavaTest {
    public static void main(String[] args) {
       MyClass<Integer> x = new MyClass<Integer>();
       x.hello();
       x.myVal();
    }
}

The ScalaTest program works correctly:

$ scala ScalaTest
HELLO

The JavaTest program throws a NoSuchMethodError when run:

$ scala JavaTest
HELLO
java.lang.NoSuchMethodError: MyClass.myVal()LMyClass;
	at JavaTest.main(JavaTest.java:5)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at scala.tools.nsc.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:78)
	at scala.tools.nsc.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:24)
	at scala.tools.nsc.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:88)
	at scala.tools.nsc.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:78)
	at scala.tools.nsc.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:101)
	at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:33)
	at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:40)
	at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:56)
	at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:80)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:89)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-6050?orig=1
Reporter: Josh Rosen (joshrosen)
Affected Versions: 2.9.2, 2.10.0-M4
Attachments:

• JavaTest.java (created on Jul 9, 2012 11:05:45 PM UTC, 164 bytes)
• ScalaTest.scala (created on Jul 9, 2012 11:05:45 PM UTC, 368 bytes)

[scabug]

@acruise said:
Observed on 2.10.0-M4 too, downloading the nightly...

[scabug]

@acruise said:
Observed on 2.10.0-20120708-165613-f82a1d122c

[scabug]

@paulp said:
This is #3452.