t7848-interp-warn.scala:7: warning: `$foo` looks like an interpolated identifier! Did you forget the interpolator?
    "An important $foo message!"
    ^
t7848-interp-warn.scala:11: warning: That looks like an interpolated expression! Did you forget the interpolator?
    "A doubly important ${foo * 2} message!"
    ^
error: No warnings can be incurred under -Xfatal-warnings.
two warnings found
one error found