t7848-interp-warn.scala:8: warning: possible missing interpolator: detected interpolated identifier `$foo`
    "An important $foo message!"
    ^
t7848-interp-warn.scala:12: warning: possible missing interpolator: detected an interpolated expression
    "A doubly important ${foo * 2} message!"
    ^
t7848-interp-warn.scala:15: warning: possible missing interpolator: detected interpolated identifier `$bar`
  def i = s"Try using '${ "$bar" }' instead."  // was: no warn on space test
                          ^
t7848-interp-warn.scala:16: warning: possible missing interpolator: detected interpolated identifier `$bar`
  def j = s"Try using '${ "something like $bar" }' instead."  // warn
                          ^
error: No warnings can be incurred under -Xfatal-warnings.
four warnings found
one error found