`@unused` ignored when compiler option `-Wunused:explicits`/`-Wunused:params` is set

[aartigao]

Compiler version

3.7.0

Minimized code

https://scastie.scala-lang.org/AcRqBnMOQvGVKyMGrNS7FQ

import scala.annotation.unused

@main def hello(): Unit =
  println(A(""))

class A(@unused param: AnyRef)

Output

-- [E198] Unused Symbol Warning
  |class A(@unused param: AnyRef)
  |                ^^^^^
  |                unused explicit parameter

Expectation

No warn emitted as the annotation should be taken into account.

[som-snytt]

This is fixed in 3.7.1-RC1 but could use a test. I don't know at a glance what fixed it.

Edit: thanks to milestoning, I'm reminded that #23037

This commit just ensures unused annotation is retained for parameters. The previous tweak excluded constructor params (probably out of fear).