Add option for stdio encoding, set stdin encoding

Language/Haskell/GhcMod/Types.hs

@@ -105,6 +105,7 @@ data Options = Options {
     -- | GHC command line options set on the @ghc-mod@ command line
   , optGhcUserOptions :: [GHCOption]
   , optFileMappings   :: [(FilePath, Maybe FilePath)]
+  , optEncoding       :: String
   } deriving (Show)
 
 -- | A default 'Options'.
@@ -124,6 +125,7 @@ defaultOptions = Options {
     }
   , optGhcUserOptions = []
   , optFileMappings   = []
+  , optEncoding       = "UTF-8"
   }
 
 ----------------------------------------------------------------

src/GHCMod.hs

@@ -34,9 +34,12 @@ handler = flip gcatches
           ]
 
 main :: IO ()
-main = do
-    hSetEncoding stdout utf8
-    parseArgs >>= \res@(globalOptions, _) ->
+main =
+    parseArgs >>= \res@(globalOptions, _) -> do
+      enc <- mkTextEncoding $ optEncoding globalOptions
+      hSetEncoding stdout enc
+      hSetEncoding stderr enc
+      hSetEncoding stdin enc
       catches (progMain res) [
               Handler $ \(e :: GhcModError) ->
                 runGmOutT globalOptions $ exitError $ renderStyle ghcModStyle (gmeDoc e)
@@ -107,7 +110,6 @@ getFileSourceFromStdin = do
         then fmap (x:) readStdin'
         else return []
 
--- Someone please already rewrite the cmdline parsing code *weep* :'(
 wrapGhcCommands :: (IOish m, GmOut m) => Options -> GhcModCommands -> m ()
 wrapGhcCommands _opts CmdRoot = gmPutStr =<< rootInfo
 wrapGhcCommands opts cmd =

src/GHCMod/Options.hs

@@ -174,6 +174,12 @@ globalArgSpec = Options
           <=> metavar "OPT"
           <=> help "Option to be passed to GHC"
       <*> many fileMappingSpec
+      <*> strOption
+          $$  long "encoding"
+          <=> short 'e'
+          <=> value "UTF-8"
+          <=> showDefault
+          <=> help "I/O encoding"
   where
     fileMappingSpec =
       getFileMapping . splitOn '=' <$> strOption