updateDynamic is not used in some contexts

[scabug]

I discovered strange behavior of updateDynamic. I trying to compile following code:

import language.dynamics

class DynamicTest extends Dynamic {
  def selectDynamic(name: String) = s"value of $name"
  def updateDynamic(name: String)(value: Any) {
    println(s"You have just updated property '$name' with value: $value")
  }
}

object MyApp extends App {
  def testing() {
    val test = new DynamicTest
    test.firstName = "John"
  }
  
  testing()
}

Which produces following compilation error:

# scalac MyApp.scala
MyApp.scala:13: error: reassignment to val
    test.firstName = "John"
                   ^

one error found

If I will remove selectDynamic method from the DynamicTest I will receive another error: "error: value selectDynamic is not a member of DynamicTest".

If I will define MyApp class like this:

object MyApp extends App {
  val test = new DynamicTest

  test.firstName = "John"
}

Then everything compiles without any errors.

BTW, I'm facing the same errors in the REPL.

[scabug]

Imported From: https://issues.scala-lang.org/browse/SI-5726?orig=1
Reporter: Oleg Ilyenko (oleg.ilyenko)
Affected Versions: 2.10.0-M3
Other Milestones: 2.10.0

[scabug]

@paulp said:
scala/scala#1681

[scabug]

@retronym said:
scala/scala@edbcc64