An annotation to be applied to a match expression. If present, the compiler will verify that the match has been compiled to a tableswitch or lookupswitch, and issue an error if it instead compiles into a series of conditional expressions.
Example:

    def fetchToken() {
      (ch: @switch) match {
        case ' ' | '\t' | CR | LF | FF =>
          nextChar()
          fetchToken()
        case 'A' /*..'Z'*/ | '$' | '_' | 'a' /*..'z'*/ =>
          putChar(ch)
          nextChar()
          getIdentRest()
        case ',' =>
          nextChar(); token = COMMA
        // more cases
      }
    }