I can call $asInstanceOf

[hrhino]

and with it, I can cause bad things to happen:

scala> "".$asInstanceOf[Symbol]
java.lang.ClassCastException: java.lang.String cannot be cast to scala.Symbol
  ... 28 elided

which, wait, I could do that already. But I can also do this:

scala> "".$asInstanceOf[Int]
ReplGlobal.abort: Erasure should have added an unboxing operation to prevent this cast. Tree: "".$asInstanceOf[Int]()
error:
  Erasure should have added an unboxing operation to prevent this cast. Tree: "".$asInstanceOf[Int]()
     while compiling: <console>
        during phase: jvm
     library version: version 2.12.11-20191213-034532-9761528
    compiler version: version 2.12.11-20191213-034532-9761528
  reconstructed args: -deprecation -feature -usejavacp

  last tree to typer: This(object iw)
       tree position: line 11 of <console>
            tree tpe: type
              symbol: object iw in package $line10
   symbol definition: class iw extends Object (a ModuleClassSymbol)
      symbol package: $line10
       symbol owners: object iw
           call site: constructor $iw in package $line10

== Source file context for tree position ==

     8 object $iw {
     9 object $iw {
    10
    11 val res1 =
    12 "".$asInstanceOf[Int]
    13
    14 }

[som-snytt]

scala.ScalaReflectionException: AnyRef.$asInstanceOf is an internal method, it cannot be invoked with mirrors

[som-snytt]

Starting dotty REPL...
scala> "".$asInstanceOf$[Int]
java.lang.ClassCastException: class java.lang.String cannot be cast to class java.lang.Integer (java.lang.String and java.lang.Integer are in module java.base of loader 'bootstrap')
	at scala.runtime.BoxesRunTime.unboxToInt(BoxesRunTime.java:99)

[SethTisue]

scala/scala#8639 was closed, but could be picked up again