t3971.scala:6: error: type mismatch;
 found   : Int
 required: String
  f(g("abc")("def")) // g returns Int, needs String
     ^
t3971.scala:7: error: type mismatch;
 found   : Int(5)
 required: String
  f(5)
    ^
t3971.scala:8: error: type mismatch;
 found   : Int
 required: String
  f(h("abc"))
     ^
t3971.scala:11: error: type mismatch;
 found   : Boolean
 required: String
  ({"ab".reverse; "ba".equals})(0): String
                               ^
four errors found