-- XXX setOptM and unsetOptM operate on different types. One should be renamed.
-setOptM :: LanguageFlag -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
+setOptM :: ExtensionFlag -> TcRnIf gbl lcl a -> TcRnIf gbl lcl a
setOptM flag = updEnv (\ env@(Env { env_top = top }) ->
env { env_top = top { hsc_dflags = lopt_set_flattened (hsc_dflags top) flag}} )