Interacting with Java's PolymorphicSignature seems broken

[oscar-broman]

Compiler version

Tried 3.1.3 and 3.2.0-RC1

Minimized code

Since this example uses the foreign incubator API, javaOptions and javacOptions must contain --add-modules=jdk.incubator.foreign

object Test {
  def main(args: Array[String]): Unit = {
    import jdk.incubator.foreign.ValueLayout.{JAVA_DOUBLE, JAVA_INT, JAVA_LONG, ADDRESS}
    import jdk.incubator.foreign.{CLinker, ResourceScope, MemorySegment, FunctionDescriptor}

    val linker = CLinker.systemCLinker()
    val strlen = linker.downcallHandle(
      linker.lookup("strlen").get(),
      FunctionDescriptor.of(JAVA_LONG, ADDRESS),
    )

    val scope = ResourceScope.newSharedScope()
    val x = MemorySegment.allocateNative(10, scope)
    x.setUtf8String(0, "Hello")
    val len = strlen.invoke(x.address())
    println(s"len = $len")
  }
}

Output

[info] running (fork) Test
[error] WARNING: Using incubator modules: jdk.incubator.foreign
[error] Exception in thread "main" java.lang.ClassCastException: Cannot cast [Ljava.lang.Object; to jdk.incubator.foreign.Addressable
[error] 	at java.base/java.lang.Class.cast(Class.java:3921)
[error] 	at Test$.main(Test.scala:15)
[error] 	at Test.main(Test.scala)
[error] Nonzero exit code returned from runner: 1
[error] (Compile / run) Nonzero exit code returned from runner: 1

Expectation

The code should run just fine, and print len = 5. It works in Scala 2.

[smarter]

Duplicate of #11332