\begin{code}
-#if __GLASGOW_HASKELL__ < 609
-try_m :: TcRn r -> TcRn (Either Exception r)
-#else
-try_m :: TcRn r -> TcRn (Either ErrorCall r)
-#endif
+try_m :: TcRn r -> TcRn (Either IOException r)
-- Does try_m, with a debug-trace on failure
try_m thing
= do { mb_r <- tryM thing ;