Send sticky logger messages to stderr #1302

Author: mgsloan

src/Stack/Types/StackT.hs

@@ -223,6 +223,7 @@ stickyLoggerFunc loc src level msg = do
     case mref of
         Nothing ->
             loggerFunc
+                out
                 loc
                 src
                 (case level of
@@ -239,7 +240,7 @@ stickyLoggerFunc loc src level msg = do
                         (maybe 0 T.length sticky)
                 clear =
                     liftIO
-                        (S8.putStr
+                        (S8.hPutStr out
                              (repeating backSpaceChar <>
                               repeating ' ' <>
                               repeating backSpaceChar))
@@ -255,26 +256,27 @@ stickyLoggerFunc loc src level msg = do
                 case level of
                     LevelOther "sticky-done" -> do
                         clear
-                        liftIO (T.putStrLn msgText)
+                        liftIO (T.hPutStrLn out msgText)
                         return Nothing
                     LevelOther "sticky" -> do
                         clear
-                        liftIO (T.putStr msgText)
+                        liftIO (T.hPutStr out msgText)
                         return (Just msgText)
                     _
                       | level >= maxLogLevel -> do
                           clear
-                          loggerFunc loc src level $ toLogStr msgText
+                          loggerFunc out loc src level $ toLogStr msgText
                           case sticky of
                               Nothing ->
                                   return Nothing
                               Just line -> do
-                                  liftIO (T.putStr line)
+                                  liftIO (T.hPutStr out line)
                                   return sticky
                       | otherwise ->
                           return sticky
             liftIO (putMVar ref newState)
   where
+    out = stderr
     msgTextRaw = T.decodeUtf8With T.lenientDecode msgBytes
     msgBytes = fromLogStr (toLogStr msg)
 
@@ -286,14 +288,13 @@ replaceUnicode c = c
 
 -- | Logging function takes the log level into account.
 loggerFunc :: (MonadIO m,ToLogStr msg,MonadReader r m,HasLogLevel r)
-           => Loc -> Text -> LogLevel -> msg -> m ()
-loggerFunc loc _src level msg =
+           => Handle -> Loc -> Text -> LogLevel -> msg -> m ()
+loggerFunc outputChannel loc _src level msg =
   do maxLogLevel <- asks getLogLevel
      when (level >= maxLogLevel)
           (liftIO (do out <- getOutput maxLogLevel
                       T.hPutStrLn outputChannel out))
-  where outputChannel = stderr
-        getOutput maxLogLevel =
+  where getOutput maxLogLevel =
           do timestamp <- getTimestamp
              l <- getLevel
              lc <- getLoc