Fix fileModuleName not working on CPP modules given by path

Language/Haskell/GhcMod/Logger.hs

@@ -3,6 +3,7 @@ module Language.Haskell.GhcMod.Logger (
   , withLogger'
   , checkErrorPrefix
   , errsToStr
+  , errBagToStrList
   ) where
 
 import Control.Arrow
@@ -93,6 +94,13 @@ withLogger' env action = do
         GHandler $ \ex -> return $ Left [render $ ghcExceptionDoc ex]
      ]
 
+errBagToStrList :: HscEnv -> Bag ErrMsg -> [String]
+errBagToStrList env errs = let
+    dflags = hsc_dflags env
+    pu = icPrintUnqual dflags (hsc_IC env)
+    st = mkUserStyle pu AllTheWay
+ in errsToStr dflags st $ bagToList errs
+
 ----------------------------------------------------------------
 
 -- | Converting 'SourceError' to 'String'.