//> using options -language:experimental.captureChecking
scala> import caps.*
scala> class IO extends SharedCapability
// defined class IO
scala> @assumeSafe val io: IO^ = null
val io: IO^ = null
scala> val x = io
val x: IO^{io} = null
scala> import language.experimental.safe
scala> val y: IO^{io} = io
val y: IO^{io} = null
scala> def f(x: Any): Unit = ()
def f(x: Any): Unit
scala> f(y)