Refactoring and tidyup of HscMain and related things (also fix #1666)

While trying to fix #1666 (-Werror aborts too early) I decided to some
tidyup in GHC/DriverPipeline/HscMain.

 - The GhcMonad overloading is gone from DriverPipeline and HscMain
   now.  GhcMonad is now defined in a module of its own, and only
   used in the top-level GHC layer.  DriverPipeline and HscMain
   use the plain IO monad and take HscEnv as an argument.

 - WarnLogMonad is gone.  printExceptionAndWarnings is now called
   printException (the old name is deprecated).  Session no longer
   contains warnings.

 - HscMain has its own little monad that collects warnings, and also
   plumbs HscEnv around.  The idea here is that warnings are collected
   while we're in HscMain, but on exit from HscMain (any function) we
   check for warnings and either print them (via log_action, so IDEs
   can still override the printing), or turn them into an error if
   -Werror is on.

 - GhcApiCallbacks is gone, along with GHC.loadWithLogger.  Thomas
   Schilling told me he wasn't using these, and I don't see a good
   reason to have them.

 - there's a new pure API to the parser (suggestion from Neil Mitchell):
      parser :: String
             -> DynFlags
             -> FilePath
             -> Either ErrorMessages (WarningMessages, 
                                      Located (HsModule RdrName))

1 files changed, 3 insertions, 13 deletions

diff --git a/ghc/GhciMonad.hs b/ghc/GhciMonad.hs
index 5494b4ea4c..82f2aa7c73 100644
--- a/ghc/GhciMonad.hs
+++ b/ghc/GhciMonad.hs
@@ -14,12 +14,13 @@ module GhciMonad where
 #include "HsVersions.h"
 
 import qualified GHC
+import GhcMonad         hiding (liftIO)
 import Outputable       hiding (printForUser, printForUserPartWay)
 import qualified Outputable
 import Panic            hiding (showException)
 import Util
 import DynFlags
-import HscTypes hiding (liftIO)
+import HscTypes
 import SrcLoc
 import Module
 import ObjLink
@@ -28,13 +29,10 @@ import StaticFlags
 import qualified MonadUtils
 
 import Exception
--- import Data.Maybe
 import Numeric
 import Data.Array
--- import Data.Char
 import Data.Int         ( Int64 )
 import Data.IORef
--- import Data.List
 import System.CPUTime
 import System.Environment
 import System.IO
@@ -181,10 +179,6 @@ instance GhcMonad (InputT GHCi) where
 instance MonadUtils.MonadIO (InputT GHCi) where
   liftIO = Trans.liftIO
 
-instance WarnLogMonad (InputT GHCi) where
-  setWarnings = lift . setWarnings
-  getWarnings = lift getWarnings
-
 instance ExceptionMonad GHCi where
   gcatch m h = GHCi $ \r -> unGHCi m r `gcatch` (\e -> unGHCi (h e) r)
   gblock (GHCi m)   = GHCi $ \r -> gblock (m r)
@@ -196,10 +190,6 @@ instance ExceptionMonad GHCi where
                              in
                                 unGHCi (f g_restore) s
 
-instance WarnLogMonad GHCi where
-  setWarnings warns = liftGhc $ setWarnings warns
-  getWarnings = liftGhc $ getWarnings
-
 instance MonadIO GHCi where
   liftIO = io
 
@@ -263,7 +253,7 @@ runStmt expr step = do
     withProgName (progname st) $
     withArgs (args st) $
       reflectGHCi x $ do
-        GHC.handleSourceError (\e -> do GHC.printExceptionAndWarnings e
+        GHC.handleSourceError (\e -> do GHC.printException e
                                         return GHC.RunFailed) $ do
           GHC.runStmt expr step