t7848-interp-warn.scala:8: warning: `$foo` looks like an interpolated identifier! Did you forget the interpolator?
    "An important $foo message!"
    ^
t7848-interp-warn.scala:12: warning: That looks like an interpolated expression! Did you forget the interpolator?
    "A doubly important ${foo * 2} message!"
    ^
t7848-interp-warn.scala:16: warning: `$bar` looks like an interpolated identifier! Did you forget the interpolator?
  def j = s"Try using '${ "something like $bar" }' instead."  // warn
                          ^
error: No warnings can be incurred under -Xfatal-warnings.
three warnings found
one error found