$> cat A.scala
trait A {
  @annotation.nowarn val x = 0
}

$> scv 2.13.2 A.scala

$> cat B.scala
class B extends A

$> scv 2.13.1 B.scala
B.scala:1: error: Symbol 'type scala.annotation.nowarn' is missing from the classpath.
This symbol is required by ' <none>'.
Make sure that type nowarn is in your classpath and check for conflicting dependencies with `-Ylog-classpath`.
A full rebuild may help if 'A.class' was compiled against an incompatible version of scala.annotation.
class B extends A
                ^
one error found