getSrcSpanM = do { env <- getLclEnv; return (tcl_loc env) }
setSrcSpan :: SrcSpan -> TcRn a -> TcRn a
-setSrcSpan loc thing_inside
- | isGoodSrcSpan loc = updLclEnv (\env -> env { tcl_loc = loc }) thing_inside
- | otherwise = thing_inside -- Don't overwrite useful info with useless
+setSrcSpan loc@(RealSrcSpan _) thing_inside
+ = updLclEnv (\env -> env { tcl_loc = loc }) thing_inside
+-- Don't overwrite useful info with useless:
+setSrcSpan (UnhelpfulSpan _) thing_inside = thing_inside
addLocM :: (a -> TcM b) -> Located a -> TcM b
addLocM fn (L loc a) = setSrcSpan loc $ fn a