1 files changed, 26 insertions, 4 deletions
diff --git a/compiler/GHC/Driver/Env.hs b/compiler/GHC/Driver/Env.hs
index 1948a91927..6606f551e5 100644
--- a/compiler/GHC/Driver/Env.hs
+++ b/compiler/GHC/Driver/Env.hs
@@ -3,10 +3,13 @@
 module GHC.Driver.Env
    ( Hsc(..)
    , HscEnv (..)
+   , hscUpdateFlags
+   , hscSetFlags
    , hsc_home_unit
    , hsc_units
    , hsc_HPT
    , hscUpdateHPT
+   , hscUpdateLoggerFlags
    , runHsc
    , runHsc'
    , mkInteractiveHscEnv
@@ -33,6 +36,7 @@ import GHC.Driver.Ppr
 import GHC.Driver.Session
 import GHC.Driver.Errors ( printOrThrowDiagnostics )
 import GHC.Driver.Errors.Types ( GhcMessage )
+import GHC.Driver.Config.Logger (initLogFlags)
 
 import GHC.Runtime.Context
 import GHC.Runtime.Interpreter.Types (Interp)
@@ -67,6 +71,7 @@ import GHC.Utils.Outputable
 import GHC.Utils.Monad
 import GHC.Utils.Panic
 import GHC.Utils.Misc
+import GHC.Utils.Logger
 import GHC.Types.Unique.FM
 
 import Data.IORef
@@ -75,7 +80,8 @@ import qualified Data.Set as Set
 runHsc :: HscEnv -> Hsc a -> IO a
 runHsc hsc_env (Hsc hsc) = do
     (a, w) <- hsc hsc_env emptyMessages
-    printOrThrowDiagnostics (hsc_logger hsc_env) (hsc_dflags hsc_env) w
+    let dflags = hsc_dflags hsc_env
+    printOrThrowDiagnostics (hsc_logger hsc_env) dflags w
     return a
 
 runHsc' :: HscEnv -> Hsc a -> IO (a, Messages GhcMessage)
@@ -85,9 +91,8 @@ runHsc' hsc_env (Hsc hsc) = hsc hsc_env emptyMessages
 mkInteractiveHscEnv :: HscEnv -> HscEnv
 mkInteractiveHscEnv hsc_env =
     let ic = hsc_IC hsc_env
-    in hsc_env { hsc_dflags  = ic_dflags  ic
-               , hsc_plugins = ic_plugins ic
-               }
+    in hscSetFlags (ic_dflags ic) $
+       hsc_env { hsc_plugins = ic_plugins ic }
 
 -- | A variant of runHsc that switches in the DynFlags and Plugins from the
 -- InteractiveContext before running the Hsc computation.
@@ -354,3 +359,20 @@ hscInterp :: HscEnv -> Interp
 hscInterp hsc_env = case hsc_interp hsc_env of
    Nothing -> throw (InstallationError "Couldn't find a target code interpreter. Try with -fexternal-interpreter")
    Just i  -> i
+
+-- | Update the LogFlags of the Log in hsc_logger from the DynFlags in
+-- hsc_dflags. You need to call this when DynFlags are modified.
+hscUpdateLoggerFlags :: HscEnv -> HscEnv
+hscUpdateLoggerFlags h = h
+  { hsc_logger = setLogFlags (hsc_logger h) (initLogFlags (hsc_dflags h)) }
+
+-- | Update Flags
+hscUpdateFlags :: (DynFlags -> DynFlags) -> HscEnv -> HscEnv
+hscUpdateFlags f h = hscSetFlags (f (hsc_dflags h)) h
+
+-- | Set Flags
+hscSetFlags :: DynFlags -> HscEnv -> HscEnv
+hscSetFlags dflags h =
+  -- update LogFlags from the new DynFlags
+  hscUpdateLoggerFlags
+  $ h { hsc_dflags = dflags }