$> cat A.java
package p;
public abstract class A {
  public abstract String s(int i);
}

$> cat Test.scala
package p
class C extends A {
  private[p] def s(i: Int) = ""
}

$> scalac Test.scala A.java

$> dotc Test.scala A.java
-- Error: Test.scala:3:17 ------------------------------------------------------
3 |  private[p] def s(i: Int) = ""
  |                 ^
  |error overriding method s in class A of type (i: Int): String;
  |  method s of type (i: Int): String has weaker access privileges; it should be public
1 error found