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.

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