Make linting work with mapped files

Language/Haskell/GhcMod/Lint.hs

@@ -8,6 +8,10 @@ import Language.Haskell.GhcMod.Monad
 import Language.Haskell.GhcMod.Types
 import Language.Haskell.HLint (hlint)
 
+import Language.Haskell.GhcMod.FileMappingUtils
+
+import Data.List (stripPrefix)
+
 -- | Checking syntax of a target file using hlint.
 --   Warnings and errors are returned.
 lint :: IOish m
@@ -15,7 +19,11 @@ lint :: IOish m
      -> GhcModT m String
 lint file = do
   opt <- options
-  ghandle handler . pack =<< liftIO (hlint $ file : "--quiet" : hlintOpts opt)
+  withMappedFile file $ \tempfile ->
+        liftIO (hlint $ tempfile : "--quiet" : hlintOpts opt)
+    >>= mapM (replaceFileName tempfile)
+    >>= ghandle handler . pack
  where
-    pack = convert' . map (init . show) -- init drops the last \n.
+    pack = convert' . map init -- init drops the last \n.
     handler (SomeException e) = return $ checkErrorPrefix ++ show e ++ "\n"
+    replaceFileName fp s = return $ maybe (show s) (file++) $ stripPrefix fp (show s)