-Wunused:imports false negative for redundant or spurious import

[som-snytt]

Compiler version

3.5.1

Minimized code

package p {
  package q {
    import q.*
    class Test {
      override def toString = new C().toString + " for Test"
    }
  }
}
package q {
  class C {
    override def toString = "q.C"
  }
}

Output

➜  snips scala compile --server=false -S 2.13.15 -Xsource:3-cross -Wunused packaging.scala
/home/amarki/snips/packaging.scala:6: error: not found: type C
      override def toString = new C().toString + " for Test"
                                  ^
/home/amarki/snips/packaging.scala:4: warning: Unused import
    import q.*
             ^
1 warning
1 error
Compilation failed
➜  snips scala compile --server=false -Wunused:all packaging.scala
-- [E006] Not Found Error: /home/amarki/snips/packaging.scala:6:34 -----------------------------------------------------
6 |      override def toString = new C().toString + " for Test"
  |                                  ^
  |                                  Not found: type C
  |
  | longer explanation available when compiling with `-explain`
1 error found
Compilation failed

Expectation

I refactored a test package from package p to

package test.p
import p.*

(in order to test public API) and was pleased that I didn't have to write import _root_.p.*.

As expected, with nested packages, the import sees the nested p.q. However, I also expected some indication that my import is spurious.

I know that importing is generous, so that if an import and definition resolve to the same symbol, it won't annoy me with cautionary messages. But I'd like a way to ask for warnings.

Scala 2 knows that the import is unused, but Scala 3 is willing to take it as used.