Verify unused

[som-snytt]

It would be nice if -Xlint also verified that an element annotated unused is in fact unused.

Currently it's just an exemption from the unused warning.

Probably it's not necessary to add an option, -Xlint:used for this case, although the LOL factor is tempting.

[dwijnand]

Agreed, there's no need for an option to disable verifying that the unused-parameter-suppressing annotation is on a parameter that is actually used.

[Jasper-M]

Agreed, there's no need for an option to disable verifying that the unused-parameter-suppressing annotation is on a parameter that is actually used.

Alternatively I would suggest -Xlint:confused.

[lrytz]

Interestingly, this is "implemented" on 2.12 with scala-collection-compat

➜ sandbox scala repl -S 2.12 --dep org.scala-lang.modules::scala-collection-compat:2.13.0
Welcome to Scala 2.12.20 (OpenJDK 64-Bit Server VM, Java 21.0.1).
Type in expressions for evaluation. Or try :help.

scala> def f(@annotation.unused x: Int) = x
<console>:11: warning: value x is deprecated
       def f(@annotation.unused x: Int) = x
                                          ^
f: (x: Int)Int