scalainheritancekeywordscala-3

Why doesn't my scalac prints any warning for missing "open" keyword

When compiling a willingly faulty Scala code implying a missing open modifier, my compiler doesn't notify any warning or error. This seems to contradict this line in the Scala book :

In Scala 3 extending non-abstract classes in other files is restricted. In order to allow this, the base class needs to be marked as open

Here is my code :

animal.scala

package animal:
    class Animal(name: String, specie: String):
        override def toString: String = s"$name of specie $specie"
        def doNoise: Unit = println("I could be anyone, really.")

cat.scala

import animal.Animal

class Cat(name: String) extends Animal(name, "cat"):
    override def doNoise: Unit = println("Meow.")

@main def run(): Unit =
    val c = Cat("felix")
    println(c)
    c.doNoise

I'm running scalac *.scala to compile all of that which runs just fine even though Cat and Animal are not defined in the same file and Animal is not marked as open. Am I missing something ?

Thanks in advance for your help :)

P.S.

When I type scala in my command line, i'm greeted with Welcome to Scala 3.4.2.

Solution

  • From Odersky himself:

    it should arrive in 3.6, later this year. It is already enabled under -source future.