Dropped: Class Shadowing
Scala 2 so far allowed patterns like this:
class Base {
class Ops { ... }
}
class Sub extends Base {
class Ops { ... }
}
Scala 3 rejects this with the error message:
6 | class Ops { }
| ^
|class Ops cannot have the same name as class Ops in class Base
| -- class definitions cannot be overridden
The issue is that the two Ops classes look like one overrides the other, but classes in Scala 2 cannot be overridden. To keep things clean (and its internal operations consistent) the Scala 3 compiler forces you to rename the inner classes so that their names are different.