import SrcLoc
import DynFlags
import Util
-import Control.Monad
+import FastString
+import Control.Monad
import Data.List
import Data.Maybe
\end{code}
-- work them out. True enough, but its not that easy!
tcIfaceAlt scrut (tycon, inst_tys) (IfaceDataAlt data_occ, arg_strs, rhs)
= do { con <- tcIfaceDataCon data_occ
-#ifdef DEBUG
- ; when (not (con `elem` tyConDataCons tycon))
+ ; when (debugIsOn && not (con `elem` tyConDataCons tycon))
(failIfM (ppr scrut $$ ppr con $$ ppr tycon $$ ppr (tyConDataCons tycon)))
-#endif
; tcIfaceDataAlt con inst_tys arg_strs rhs }
tcIfaceAlt _ (tycon, inst_tys) (IfaceTupleAlt boxity, arg_occs, rhs)