Overriding parameterless trait methods when cross compiling

[kyri-petrou]

Hi there. I'm trying to cross compile a library to Scala 3, but I'm stuck with the following:

In Scala 2.12 / 2.13 the following is allowed:

trait Foo {
  def foo(): String
}

case class Bar(override val foo: String) extends Foo

However, in Scala 3, the following error is raised:

error overriding method foo in trait Foo of type (): String;
  value foo of type String has incompatible type
case class Bar(foo: String) extends Foo

Is there anything that could be done in this case (e.g., a compiler flag) to allow this code to be cross-compiled for both Scala 2 and 3?