unit-returns-value.scala:4: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
    if (b) return 5
                  ^
unit-returns-value.scala:4: warning: enclosing method f has result type Unit: return value discarded
    if (b) return 5
           ^
unit-returns-value.scala:22: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
    i1 // warn
    ^
unit-returns-value.scala:23: warning: a pure expression does nothing in statement position; you may be omitting necessary parentheses
    i2 // warn
    ^
error: No warnings can be incurred under -Xfatal-warnings.
four warnings found
one error found