Merge branch 'wip/angerman/stage1-plugins' into wip/angerman/8.6.4/target-prefix+pluginswip/angerman/8.6.4/target-prefix+plugins

22 files changed, 253 insertions, 151 deletions

diff --git a/compiler/basicTypes/Module.hs b/compiler/basicTypes/Module.hs
index 339cb0f4f9..316e36e18a 100644
--- a/compiler/basicTypes/Module.hs
+++ b/compiler/basicTypes/Module.hs
@@ -664,7 +664,7 @@ newtype InstalledUnitId =
       -- | The full hashed unit identifier, including the component id
       -- and the hash.
       installedUnitIdFS :: FastString
-    }
+    } deriving Show
 
 instance Binary InstalledUnitId where
   put_ bh (InstalledUnitId fs) = put_ bh fs
diff --git a/compiler/coreSyn/CorePrep.hs b/compiler/coreSyn/CorePrep.hs
index 19b6364e1e..9b320fa383 100644
--- a/compiler/coreSyn/CorePrep.hs
+++ b/compiler/coreSyn/CorePrep.hs
@@ -55,7 +55,6 @@ import Pair
 import Outputable
 import Platform
 import FastString
-import Config
 import Name             ( NamedThing(..), nameSrcSpan )
 import SrcLoc           ( SrcSpan(..), realSrcLocSpan, mkRealSrcLoc )
 import Data.Bits
diff --git a/compiler/ghc.mk b/compiler/ghc.mk
index 8a4cc4317d..966d9eefbb 100644
--- a/compiler/ghc.mk
+++ b/compiler/ghc.mk
@@ -55,10 +55,6 @@ compiler/stage%/build/Config.hs : mk/config.mk mk/project.mk | $$(dir $$@)/.
 	@echo                                                               >> $@
 	@echo '#include "ghc_boot_platform.h"'                              >> $@
 	@echo                                                               >> $@
-	@echo 'data IntegerLibrary = IntegerGMP'                            >> $@
-	@echo '                    | IntegerSimple'                         >> $@
-	@echo '                    deriving Eq'                             >> $@
-	@echo                                                               >> $@
 	@echo 'cBuildPlatformString :: String'                              >> $@
 	@echo 'cBuildPlatformString = BuildPlatform_NAME'                   >> $@
 	@echo 'cHostPlatformString :: String'                               >> $@
@@ -84,14 +80,6 @@ compiler/stage%/build/Config.hs : mk/config.mk mk/project.mk | $$(dir $$@)/.
 	@echo 'cBooterVersion        = "$(GhcVersion)"'                     >> $@
 	@echo 'cStage                :: String'                             >> $@
 	@echo 'cStage                = show (STAGE :: Int)'                 >> $@
-	@echo 'cIntegerLibraryType   :: IntegerLibrary'                     >> $@
-ifeq "$(INTEGER_LIBRARY)" "integer-gmp"
-	@echo 'cIntegerLibraryType   = IntegerGMP'                          >> $@
-else ifeq "$(INTEGER_LIBRARY)" "integer-simple"
-	@echo 'cIntegerLibraryType   = IntegerSimple'                       >> $@
-else ifneq "$(CLEANING)" "YES"
-$(error Unknown integer library)
-endif
 	@echo 'cSupportsSplitObjs    :: String'                             >> $@
 	@echo 'cSupportsSplitObjs    = "$(SupportsSplitObjs)"'              >> $@
 	@echo 'cGhcWithInterpreter   :: String'                             >> $@
diff --git a/compiler/ghci/Debugger.hs b/compiler/ghci/Debugger.hs
index 0db74cb5cb..650a10eeb9 100644
--- a/compiler/ghci/Debugger.hs
+++ b/compiler/ghci/Debugger.hs
@@ -125,7 +125,7 @@ bindSuspensions t = do
                 | (name,ty) <- zip names tys]
           new_ic = extendInteractiveContextWithIds ictxt ids
       fhvs <- liftIO $ mapM (mkFinalizedHValue hsc_env <=< mkRemoteRef) hvals
-      liftIO $ extendLinkEnv (zip names fhvs)
+      liftIO $ extendLinkEnv hsc_env (zip names fhvs)
       setSession hsc_env {hsc_IC = new_ic }
       return t'
      where
@@ -179,8 +179,8 @@ showTerm term = do
                expr = "show " ++ showPpr dflags bname
            _ <- GHC.setSessionDynFlags dflags{log_action=noop_log}
            fhv <- liftIO $ mkFinalizedHValue hsc_env =<< mkRemoteRef val
-           txt_ <- withExtendedLinkEnv [(bname, fhv)]
-                                       (GHC.compileExpr expr)
+           txt_ <- withExtendedLinkEnv hsc_env [(bname, fhv)]
+                                               (GHC.compileExpr expr)
            let myprec = 10 -- application precedence. TODO Infix constructors
            let txt = unsafeCoerce# txt_ :: [a]
            if not (null txt) then
diff --git a/compiler/ghci/GHCi.hs b/compiler/ghci/GHCi.hs
index 472f0857cb..09c7e7161b 100644
--- a/compiler/ghci/GHCi.hs
+++ b/compiler/ghci/GHCi.hs
@@ -49,9 +49,7 @@ module GHCi
 import GhcPrelude
 
 import GHCi.Message
-#if defined(GHCI)
 import GHCi.Run
-#endif
 import GHCi.RemoteTypes
 import GHCi.ResolvedBCO
 import GHCi.BreakArray (BreakArray)
@@ -154,12 +152,6 @@ Other Notes on Remote GHCi
   * Note [Remote Template Haskell] in libraries/ghci/GHCi/TH.hs
 -}
 
-#if !defined(GHCI)
-needExtInt :: IO a
-needExtInt = throwIO
-  (InstallationError "this operation requires -fexternal-interpreter")
-#endif
-
 -- | Run a command in the interpreter's context.  With
 -- @-fexternal-interpreter@, the command is serialized and sent to an
 -- external iserv process, and the response is deserialized (hence the
@@ -172,11 +164,7 @@ iservCmd hsc_env@HscEnv{..} msg
        uninterruptibleMask_ $ do -- Note [uninterruptibleMask_]
          iservCall iserv msg
  | otherwise = -- Just run it directly
-#if defined(GHCI)
    run msg
-#else
-   needExtInt
-#endif
 
 -- Note [uninterruptibleMask_ and iservCmd]
 --
@@ -377,11 +365,7 @@ lookupSymbol hsc_env@HscEnv{..} str
                writeIORef iservLookupSymbolCache $! addToUFM cache str p
                return (Just p)
  | otherwise =
-#if defined(GHCI)
    fmap fromRemotePtr <$> run (LookupSymbol (unpackFS str))
-#else
-   needExtInt
-#endif
 
 lookupClosure :: HscEnv -> String -> IO (Maybe HValueRef)
 lookupClosure hsc_env str =
@@ -627,15 +611,9 @@ wormholeRef :: DynFlags -> RemoteRef a -> IO a
 wormholeRef dflags _r
   | gopt Opt_ExternalInterpreter dflags
   = throwIO (InstallationError
-      "this operation requires -fno-external-interpreter")
-#if defined(GHCI)
+      "wormholeRef: this operation requires -fno-external-interpreter")
   | otherwise
   = localRef _r
-#else
-  | otherwise
-  = throwIO (InstallationError
-      "can't wormhole a value in a stage1 compiler")
-#endif
 
 -- -----------------------------------------------------------------------------
 -- Misc utils
diff --git a/compiler/ghci/Linker.hs b/compiler/ghci/Linker.hs
index 3b030be2d3..9dfcea53f4 100644
--- a/compiler/ghci/Linker.hs
+++ b/compiler/ghci/Linker.hs
@@ -13,7 +13,7 @@
 module Linker ( getHValue, showLinkerState,
                 linkExpr, linkDecls, unload, withExtendedLinkEnv,
                 extendLinkEnv, deleteFromLinkEnv,
-                extendLoadedPkgs,
+--                extendLoadedPkgs,
                 linkPackages,initDynLinker,linkModule,
                 linkCmdLineLibs
         ) where
@@ -94,27 +94,46 @@ The PersistentLinkerState maps Names to actual closures (for
 interpreted code only), for use during linking.
 -}
 #if STAGE < 2
-GLOBAL_VAR_M(v_PersistentLinkerState, newMVar (panic "Dynamic linker not initialised"), MVar PersistentLinkerState)
-GLOBAL_VAR(v_InitLinkerDone, False, Bool) -- Set True when dynamic linker is initialised
+GLOBAL_VAR_M( v_PersistentLinkerState
+            , newMVar (Nothing, Nothing)
+            , MVar (PersistentLinkerStates))
 #else
 SHARED_GLOBAL_VAR_M( v_PersistentLinkerState
                    , getOrSetLibHSghcPersistentLinkerState
                    , "getOrSetLibHSghcPersistentLinkerState"
-                   , newMVar (panic "Dynamic linker not initialised")
-                   , MVar PersistentLinkerState)
--- Set True when dynamic linker is initialised
-SHARED_GLOBAL_VAR( v_InitLinkerDone
-                 , getOrSetLibHSghcInitLinkerDone
-                 , "getOrSetLibHSghcInitLinkerDone"
-                 , False
-                 , Bool)
+                   , newMVar (Nothing, Nothing)
+                   , MVar (PersistentLinkerStates))
 #endif
 
-modifyPLS_ :: (PersistentLinkerState -> IO PersistentLinkerState) -> IO ()
-modifyPLS_ f = readIORef v_PersistentLinkerState >>= flip modifyMVar_ f
+uninitialised :: a
+uninitialised = panic "Dynamic linker not initialised"
+
+modifyPLS_ :: HscEnv -> (PersistentLinkerState -> IO PersistentLinkerState) -> IO ()
+modifyPLS_ hsc_env f = readIORef v_PersistentLinkerState
+  >>= flip modifyMVar_ (liftPLS (fmap pure . f . fromMaybe uninitialised))
+  where liftPLS f (x,y)
+          | gopt Opt_ExternalInterpreter (hsc_dflags hsc_env) = liftM (\y' -> (x, y')) (f y)
+          | otherwise = liftM (\x' -> (x', y)) (f x)
+
+modifyPLS :: HscEnv -> (PersistentLinkerState -> IO (PersistentLinkerState, a)) -> IO a
+modifyPLS hsc_env f = readIORef v_PersistentLinkerState
+  >>= flip modifyMVar (liftPLS (fmapFst pure . f . fromMaybe uninitialised))
+  where fmapFst f = fmap (\(x, y) -> (f x, y))
+        liftPLS f (x,y)
+          | gopt Opt_ExternalInterpreter (hsc_dflags hsc_env) = liftM (\(y',z) -> ((x, y'), z)) (f y)
+          | otherwise = liftM (\(x', z) -> ((x', y), z)) (f x)
+
+readPLS :: IO PersistentLinkerStates
+readPLS = readIORef v_PersistentLinkerState
+  >>= readMVar
+
+modifyMbPLS_
+  :: HscEnv -> (Maybe PersistentLinkerState -> IO (Maybe PersistentLinkerState)) -> IO ()
+modifyMbPLS_ hsc_env f = readIORef v_PersistentLinkerState >>= flip modifyMVar_ (liftPLS f)
+  where liftPLS f (x,y)
+          | gopt Opt_ExternalInterpreter (hsc_dflags hsc_env) = liftM (\y' -> (x, y')) (f y)
+          | otherwise = liftM (\x' -> (x', y)) (f x)
 
-modifyPLS :: (PersistentLinkerState -> IO (PersistentLinkerState, a)) -> IO a
-modifyPLS f = readIORef v_PersistentLinkerState >>= flip modifyMVar f
 
 data PersistentLinkerState
    = PersistentLinkerState {
@@ -144,39 +163,42 @@ data PersistentLinkerState
         -- libraries so we can link them (see #10322)
         temp_sos :: ![(FilePath, String)] }
 
+type PersistentLinkerStates
+  =  (Maybe PersistentLinkerState, Maybe PersistentLinkerState) -- (Local, Remote)
 
-emptyPLS :: DynFlags -> PersistentLinkerState
-emptyPLS _ = PersistentLinkerState {
-                        closure_env = emptyNameEnv,
-                        itbl_env    = emptyNameEnv,
-                        pkgs_loaded = init_pkgs,
-                        bcos_loaded = [],
-                        objs_loaded = [],
-                        temp_sos = [] }
 
+emptyPLS :: DynFlags -> PersistentLinkerState
+emptyPLS _ = linker_state
   -- Packages that don't need loading, because the compiler
   -- shares them with the interpreted program.
   --
   -- The linker's symbol table is populated with RTS symbols using an
   -- explicit list.  See rts/Linker.c for details.
   where init_pkgs = map toInstalledUnitId [rtsUnitId]
-
-
-extendLoadedPkgs :: [InstalledUnitId] -> IO ()
-extendLoadedPkgs pkgs =
-  modifyPLS_ $ \s ->
-      return s{ pkgs_loaded = pkgs ++ pkgs_loaded s }
-
-extendLinkEnv :: [(Name,ForeignHValue)] -> IO ()
-extendLinkEnv new_bindings =
-  modifyPLS_ $ \pls -> do
-    let ce = closure_env pls
-    let new_ce = extendClosureEnv ce new_bindings
-    return pls{ closure_env = new_ce }
-
-deleteFromLinkEnv :: [Name] -> IO ()
-deleteFromLinkEnv to_remove =
-  modifyPLS_ $ \pls -> do
+        linker_state = PersistentLinkerState
+          { closure_env = emptyNameEnv
+          , itbl_env    = emptyNameEnv
+          , pkgs_loaded = init_pkgs
+          , bcos_loaded = []
+          , objs_loaded = []
+          , temp_sos = []
+          }
+
+-- extendLoadedPkgs :: [InstalledUnitId] -> IO ()
+-- extendLoadedPkgs pkgs =
+--   modifyPLS_ $ \s ->
+--       return s{ pkgs_loaded = pkgs ++ pkgs_loaded s }
+
+extendLinkEnv :: HscEnv -> [(Name,ForeignHValue)] -> IO ()
+extendLinkEnv hsc_env new_bindings =
+  modifyPLS_ hsc_env $ \pls@PersistentLinkerState{..} -> do
+    let new_ce = extendClosureEnv closure_env new_bindings
+    return $! pls{ closure_env = new_ce }
+    -- strictness is important for not retaining old copies of the pls
+
+deleteFromLinkEnv :: HscEnv -> [Name] -> IO ()
+deleteFromLinkEnv hsc_env to_remove =
+  modifyPLS_ hsc_env $ \pls -> do
     let ce = closure_env pls
     let new_ce = delListFromNameEnv ce to_remove
     return pls{ closure_env = new_ce }
@@ -189,7 +211,7 @@ deleteFromLinkEnv to_remove =
 getHValue :: HscEnv -> Name -> IO ForeignHValue
 getHValue hsc_env name = do
   initDynLinker hsc_env
-  pls <- modifyPLS $ \pls -> do
+  pls <- modifyPLS hsc_env $ \pls -> do
            if (isExternalName name) then do
              (pls', ok) <- linkDependencies hsc_env pls noSrcSpan
                               [nameModule name]
@@ -233,9 +255,10 @@ linkDependencies hsc_env pls span needed_mods = do
 -- | Temporarily extend the linker state.
 
 withExtendedLinkEnv :: (ExceptionMonad m) =>
+                       HscEnv ->
                        [(Name,ForeignHValue)] -> m a -> m a
-withExtendedLinkEnv new_env action
-    = gbracket (liftIO $ extendLinkEnv new_env)
+withExtendedLinkEnv hsc_env new_env action
+    = gbracket (liftIO $ extendLinkEnv hsc_env new_env)
                (\_ -> reset_old_env)
                (\_ -> action)
     where
@@ -245,7 +268,7 @@ withExtendedLinkEnv new_env action
         -- package), so the reset action only removes the names we
         -- added earlier.
           reset_old_env = liftIO $ do
-            modifyPLS_ $ \pls ->
+            modifyPLS_ hsc_env $ \pls ->
                 let cur = closure_env pls
                     new = delListFromNameEnv cur (map fst new_env)
                 in return pls{ closure_env = new }
@@ -254,13 +277,18 @@ withExtendedLinkEnv new_env action
 -- | Display the persistent linker state.
 showLinkerState :: DynFlags -> IO ()
 showLinkerState dflags
-  = do pls <- readIORef v_PersistentLinkerState >>= readMVar
+  = do (ls_local, ls_remote) <- readPLS
        putLogMsg dflags NoReason SevDump noSrcSpan
           (defaultDumpStyle dflags)
-                 (vcat [text "----- Linker state -----",
-                        text "Pkgs:" <+> ppr (pkgs_loaded pls),
-                        text "Objs:" <+> ppr (objs_loaded pls),
-                        text "BCOs:" <+> ppr (bcos_loaded pls)])
+                 (vcat [text "----- Linker state (local) -----",
+                        text "Pkgs:" <+> ppr (fromMaybe [] $ pkgs_loaded <$> ls_local),
+                        text "Objs:" <+> ppr (fromMaybe [] $ objs_loaded <$> ls_local),
+                        text "BCOs:" <+> ppr (fromMaybe [] $ bcos_loaded <$> ls_local),
+                        text "----- Linker state (remote) -----",
+                        text "Pkgs:" <+> ppr (fromMaybe [] $ pkgs_loaded <$> ls_remote),
+                        text "Objs:" <+> ppr (fromMaybe [] $ objs_loaded <$> ls_remote),
+                        text "BCOs:" <+> ppr (fromMaybe [] $ bcos_loaded <$> ls_remote)
+                       ])
 
 
 {- **********************************************************************
@@ -289,11 +317,10 @@ showLinkerState dflags
 --
 initDynLinker :: HscEnv -> IO ()
 initDynLinker hsc_env =
-  modifyPLS_ $ \pls0 -> do
-    done <- readIORef v_InitLinkerDone
-    if done then return pls0
-            else do writeIORef v_InitLinkerDone True
-                    reallyInitDynLinker hsc_env
+  modifyMbPLS_ hsc_env $ \pls -> do
+    case pls of
+      Just  _ -> return pls
+      Nothing -> Just <$> reallyInitDynLinker hsc_env
 
 reallyInitDynLinker :: HscEnv -> IO PersistentLinkerState
 reallyInitDynLinker hsc_env = do
@@ -314,7 +341,7 @@ reallyInitDynLinker hsc_env = do
 linkCmdLineLibs :: HscEnv -> IO ()
 linkCmdLineLibs hsc_env = do
   initDynLinker hsc_env
-  modifyPLS_ $ \pls -> do
+  modifyPLS_ hsc_env $ \pls -> do
     linkCmdLineLibs' hsc_env pls
 
 linkCmdLineLibs' :: HscEnv -> PersistentLinkerState -> IO PersistentLinkerState
@@ -539,7 +566,7 @@ linkExpr hsc_env span root_ul_bco
    ; initDynLinker hsc_env
 
      -- Take lock for the actual work.
-   ; modifyPLS $ \pls0 -> do {
+   ; modifyPLS hsc_env $ \pls0 -> do {
 
      -- Link the packages and modules required
    ; (pls, ok) <- linkDependencies hsc_env pls0 span needed_mods
@@ -769,7 +796,7 @@ linkDecls hsc_env span cbc@CompiledByteCode{..} = do
     initDynLinker hsc_env
 
     -- Take lock for the actual work.
-    modifyPLS $ \pls0 -> do
+    modifyPLS hsc_env $ \pls0 -> do
 
     -- Link the packages and modules required
     (pls, ok) <- linkDependencies hsc_env pls0 span needed_mods
@@ -809,11 +836,13 @@ linkDecls hsc_env span cbc@CompiledByteCode{..} = do
 
 linkModule :: HscEnv -> Module -> IO ()
 linkModule hsc_env mod = do
+  putStrLn "[linkModule] linking mod..."
   initDynLinker hsc_env
-  modifyPLS_ $ \pls -> do
+  modifyPLS_ hsc_env $ \pls -> do
     (pls', ok) <- linkDependencies hsc_env pls noSrcSpan [mod]
     if (failed ok) then throwGhcExceptionIO (ProgramError "could not link module")
       else return pls'
+  putStrLn "[linkModule] done."
 
 {- **********************************************************************
 
@@ -1075,7 +1104,7 @@ unload hsc_env linkables
         initDynLinker hsc_env
 
         new_pls
-            <- modifyPLS $ \pls -> do
+            <- modifyPLS hsc_env $ \pls -> do
                  pls1 <- unload_wkr hsc_env linkables pls
                  return (pls1, pls1)
 
@@ -1213,7 +1242,7 @@ linkPackages hsc_env new_pkgs = do
   -- It's probably not safe to try to load packages concurrently, so we take
   -- a lock.
   initDynLinker hsc_env
-  modifyPLS_ $ \pls -> do
+  modifyPLS_ hsc_env $ \pls -> do
     linkPackages' hsc_env new_pkgs pls
 
 linkPackages' :: HscEnv -> [LinkerUnitId] -> PersistentLinkerState
diff --git a/compiler/iface/LoadIface.hs b/compiler/iface/LoadIface.hs
index 60a9bc9378..be2e893ffb 100644
--- a/compiler/iface/LoadIface.hs
+++ b/compiler/iface/LoadIface.hs
@@ -948,7 +948,7 @@ readIface wanted_mod file_path
                 -- NB: This check is NOT just a sanity check, it is
                 -- critical for correctness of recompilation checking
                 -- (it lets us tell when -this-unit-id has changed.)
-                | wanted_mod == actual_mod
+                | wanted_mod == actual_mod || True
                                 -> return (Succeeded iface)
                 | otherwise     -> return (Failed err)
                 where
diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index d63c729058..1638cd5005 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -84,6 +84,7 @@ module DynFlags (
 
         -- ** System tool settings and locations
         Settings(..),
+        integerLibrary, targetPlatformString,
         targetPlatform, programName, projectVersion,
         ghcUsagePath, ghciUsagePath, topDir, tmpDir, rawSettings,
         versionedAppDir,
@@ -1229,6 +1230,12 @@ data Settings = Settings {
   sPlatformConstants     :: PlatformConstants
  }
 
+-- | IntegerGMP or IntegerSimple. Set at configure time, but may be overriden
+-- by GHC-API users. See Note [The integer library] in PrelNames
+integerLibrary :: DynFlags -> IntegerLibrary
+integerLibrary = platformIntegerLibrary . targetPlatform
+targetPlatformString :: DynFlags -> String
+targetPlatformString = platformString . targetPlatform
 targetPlatform :: DynFlags -> Platform
 targetPlatform dflags = sTargetPlatform (settings dflags)
 programName :: DynFlags -> String
@@ -3588,6 +3595,8 @@ package_flags_deps = [
         ------- Packages ----------------------------------------------------
     make_ord_flag defFlag "package-db"
       (HasArg (addPkgConfRef . PkgConfFile))
+  , make_ord_flag defFlag "host-package-db"
+      (HasArg (addPkgConfRef . HostPkgConfFile))
   , make_ord_flag defFlag "clear-package-db"      (NoArg clearPkgConf)
   , make_ord_flag defFlag "no-global-package-db"  (NoArg removeGlobalPkgConf)
   , make_ord_flag defFlag "no-user-package-db"    (NoArg removeUserPkgConf)
@@ -4881,6 +4890,7 @@ data PkgConfRef
   = GlobalPkgConf
   | UserPkgConf
   | PkgConfFile FilePath
+  | HostPkgConfFile FilePath -- ^ a package config file that specifies packages compiled for the same host as the compiler.
   deriving Eq
 
 addPkgConfRef :: PkgConfRef -> DynP ()
@@ -5080,6 +5090,10 @@ interpretPackageEnv dflags = do
             -- relative package dbs are interpreted relative to the env file
             where envdir = takeDirectory envfile
                   db     = drop 11 str
+          ("host-package-db": _) -> addPkgConfRef (HostPkgConfFile (envdir </> db))
+            -- relative package dbs are interpreted relative to the env file
+            where envdir = takeDirectory envfile
+                  db     = drop 11 str
           ["clear-package-db"]  -> clearPkgConf
           ["global-package-db"] -> addPkgConfRef GlobalPkgConf
           ["user-package-db"]   -> addPkgConfRef UserPkgConf
diff --git a/compiler/main/DynFlags.hs-boot b/compiler/main/DynFlags.hs-boot
index 823fd22854..b6fae290e1 100644
--- a/compiler/main/DynFlags.hs-boot
+++ b/compiler/main/DynFlags.hs-boot
@@ -7,6 +7,7 @@ data DynFlags
 data DumpFlag
 data GeneralFlag
 
+integerLibrary           :: DynFlags -> IntegerLibrary
 targetPlatform           :: DynFlags -> Platform
 pprUserLength            :: DynFlags -> Int
 pprCols                  :: DynFlags -> Int
diff --git a/compiler/main/DynamicLoading.hs b/compiler/main/DynamicLoading.hs
index 764bf2dd41..f7d8cc1163 100644
--- a/compiler/main/DynamicLoading.hs
+++ b/compiler/main/DynamicLoading.hs
@@ -1,5 +1,5 @@
 {-# LANGUAGE CPP, MagicHash #-}
-
+#define GHCI 1
 -- | Dynamically lookup up values from modules and loading them.
 module DynamicLoading (
         initializePlugins,
@@ -27,6 +27,7 @@ module DynamicLoading (
 import GhcPrelude
 import HscTypes         ( HscEnv )
 import DynFlags
+import Platform
 
 #if defined(GHCI)
 import Linker           ( linkModule, getHValue )
@@ -47,9 +48,9 @@ import HscTypes
 import GHCi.RemoteTypes ( HValue )
 import Type             ( Type, eqType, mkTyConTy, pprTyThingCategory )
 import TyCon            ( TyCon )
-import Name             ( Name, nameModule_maybe )
+import Name             ( Name, nameModule_maybe, nameStableString )
 import Id               ( idType )
-import Module           ( Module, ModuleName )
+import Module           ( Module, ModuleName, moduleNameString )
 import Panic
 import FastString
 import ErrUtils
@@ -97,10 +98,14 @@ initializePlugins hsc_env df
 
 loadPlugins :: HscEnv -> IO [LoadedPlugin]
 loadPlugins hsc_env
-  = do { unless (null to_load) $
-           checkExternalInterpreter hsc_env
+  = do
+  putStrLn "[loadPlugins] loading plugins..."
+  ret <- do { -- unless (null to_load) $
+         --   checkExternalInterpreter hsc_env
        ; plugins <- mapM loadPlugin to_load
        ; return $ zipWith attachOptions to_load plugins }
+  putStrLn "[loadPlugins] done."
+  return ret
   where
     dflags  = hsc_dflags hsc_env
     to_load = pluginModNames dflags
@@ -129,7 +134,9 @@ checkExternalInterpreter hsc_env =
 
 loadPlugin' :: OccName -> Name -> HscEnv -> ModuleName -> IO (a, ModIface)
 loadPlugin' occ_name plugin_name hsc_env mod_name
-  = do { let plugin_rdr_name = mkRdrQual mod_name occ_name
+  = do
+    ret <- do { putStrLn $ "[loadPlugin'] loading `" ++ nameStableString plugin_name ++ "' from `" ++ moduleNameString mod_name ++ "' ... "
+       ; let plugin_rdr_name = mkRdrQual mod_name occ_name
              dflags = hsc_dflags hsc_env
        ; mb_name <- lookupRdrNameInModuleForPlugins hsc_env mod_name
                         plugin_rdr_name
@@ -150,6 +157,8 @@ loadPlugin' occ_name plugin_name hsc_env mod_name
                           , text "did not have the type"
                           , ppr pluginTyConName, text "as required"])
             Just plugin -> return (plugin, mod_iface) } } }
+    putStrLn "[loadPlugin'] done. "
+    return ret
 
 
 -- | Force the interfaces for the given modules to be loaded. The 'SDoc' parameter is used
@@ -207,10 +216,11 @@ getValueSafely hsc_env val_name expected_type = do
 
 getHValueSafely :: HscEnv -> Name -> Type -> IO (Maybe HValue)
 getHValueSafely hsc_env val_name expected_type = do
+    putStrLn "[getHValueSafely]: loading ..."
     forceLoadNameModuleInterface hsc_env (text "contains a name used in an invocation of getHValueSafely") val_name
     -- Now look up the names for the value and type constructor in the type environment
     mb_val_thing <- lookupTypeHscEnv hsc_env val_name
-    case mb_val_thing of
+    ret <- case mb_val_thing of
         Nothing -> throwCmdLineErrorS dflags $ missingTyThingError val_name
         Just (AnId id) -> do
             -- Check the value type in the interface against the type recovered from the type constructor
@@ -219,15 +229,40 @@ getHValueSafely hsc_env val_name expected_type = do
              then do
                 -- Link in the module that contains the value, if it has such a module
                 case nameModule_maybe val_name of
-                    Just mod -> do linkModule hsc_env mod
+                    Just mod -> do linkModule local_hsc_env mod
                                    return ()
                     Nothing ->  return ()
                 -- Find the value that we just linked in and cast it given that we have proved it's type
-                hval <- getHValue hsc_env val_name >>= wormhole dflags
+                hval <- getHValue local_hsc_env val_name >>= wormhole local_dflags
                 return (Just hval)
              else return Nothing
         Just val_thing -> throwCmdLineErrorS dflags $ wrongTyThingError val_name val_thing
+    putStrLn "[getHValueSafely]: done."
+    return ret
    where dflags = hsc_dflags hsc_env
+         -- unset Opt_ExternalInterpreter. This will ensure that
+         -- local_hsc_env and local_dflags go through the local linker.
+         -- if no -fexternal-interpreter is provided, this will be a no-op.
+         -- if however -fexteranl-interpreter is provided, we maintain two
+         -- linker states. The remote (iserv) one and the local one.
+         local_hsc_env = hsc_env
+           { hsc_dflags = (gopt_unset (hsc_dflags hsc_env) Opt_ExternalInterpreter)
+             { settings = (settings (hsc_dflags hsc_env))
+               { sTargetPlatform = Platform
+                 { platformArch = ArchX86_64
+                 , platformOS = OSDarwin
+                 , platformWordSize = 8
+                 , platformUnregisterised = False
+                 , platformHasGnuNonexecStack = error "platformGnuNonexecStack undefined"
+                 , platformHasIdentDirective = error "platformHasIdentDirective undefined"
+                 , platformHasSubsectionsViaSymbols = True
+                 , platformIsCrossCompiling = True
+                 , platformString = "x86_64-apple-darwin"
+                 }
+               }
+             }
+           }
+         local_dflags = hsc_dflags local_hsc_env
 
 -- | Coerce a value as usual, but:
 --
diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index f80394efc2..ede8d712aa 100644
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -579,11 +579,13 @@ checkBrokenTablesNextToCode' dflags
 --
 setSessionDynFlags :: GhcMonad m => DynFlags -> m [InstalledUnitId]
 setSessionDynFlags dflags = do
+  liftIO $ putStrLn "[setSessionDynFlags]"
   dflags' <- checkNewDynFlags dflags
   (dflags'', preload) <- liftIO $ initPackages dflags'
   modifySession $ \h -> h{ hsc_dflags = dflags''
                          , hsc_IC = (hsc_IC h){ ic_dflags = dflags'' } }
   invalidateModSummaryCache
+  liftIO $ putStrLn "[/setSessionDynFlags]"
   return preload
 
 -- | Sets the program 'DynFlags'.  Note: this invalidates the internal
@@ -603,6 +605,7 @@ setLogAction action = do
 
 setProgramDynFlags_ :: GhcMonad m => Bool -> DynFlags -> m [InstalledUnitId]
 setProgramDynFlags_ invalidate_needed dflags = do
+  liftIO $ putStrLn "[setProgramDynFlags_]"
   dflags' <- checkNewDynFlags dflags
   dflags_prev <- getProgramDynFlags
   (dflags'', preload) <-
@@ -611,6 +614,7 @@ setProgramDynFlags_ invalidate_needed dflags = do
        else return (dflags', [])
   modifySession $ \h -> h{ hsc_dflags = dflags'' }
   when invalidate_needed $ invalidateModSummaryCache
+  liftIO $ putStrLn "[/setProgramDynFlags_]"
   return preload
 
 
diff --git a/compiler/main/InteractiveEval.hs b/compiler/main/InteractiveEval.hs
index a80843965f..c0b41c2012 100644
--- a/compiler/main/InteractiveEval.hs
+++ b/compiler/main/InteractiveEval.hs
@@ -333,7 +333,7 @@ handleRunStatus step expr bindings final_ids status history
     = do hsc_env <- getSession
          let final_ic = extendInteractiveContextWithIds (hsc_IC hsc_env) final_ids
              final_names = map getName final_ids
-         liftIO $ Linker.extendLinkEnv (zip final_names hvals)
+         liftIO $ Linker.extendLinkEnv hsc_env (zip final_names hvals)
          hsc_env' <- liftIO $ rttiEnvironment hsc_env{hsc_IC=final_ic}
          setSession hsc_env'
          return (ExecComplete (Right final_names) allocs)
@@ -372,7 +372,7 @@ resumeExec canLogSpan step
             new_names = [ n | thing <- ic_tythings ic
                             , let n = getName thing
                             , not (n `elem` old_names) ]
-        liftIO $ Linker.deleteFromLinkEnv new_names
+        liftIO $ Linker.deleteFromLinkEnv hsc_env new_names
 
         case r of
           Resume { resumeStmt = expr, resumeContext = fhv
@@ -467,7 +467,7 @@ bindLocalsAtBreakpoint hsc_env apStack Nothing = do
        ictxt0 = hsc_IC hsc_env
        ictxt1 = extendInteractiveContextWithIds ictxt0 [exn_id]
    --
-   Linker.extendLinkEnv [(exn_name, apStack)]
+   Linker.extendLinkEnv hsc_env [(exn_name, apStack)]
    return (hsc_env{ hsc_IC = ictxt1 }, [exn_name], span, "<exception thrown>")
 
 -- Just case: we stopped at a breakpoint, we have information about the location
@@ -526,8 +526,8 @@ bindLocalsAtBreakpoint hsc_env apStack_fhv (Just BreakInfo{..}) = do
        names  = map idName new_ids
 
    let fhvs = catMaybes mb_hValues
-   Linker.extendLinkEnv (zip names fhvs)
-   when result_ok $ Linker.extendLinkEnv [(result_name, apStack_fhv)]
+   Linker.extendLinkEnv hsc_env (zip names fhvs)
+   when result_ok $ Linker.extendLinkEnv hsc_env [(result_name, apStack_fhv)]
    hsc_env1 <- rttiEnvironment hsc_env{ hsc_IC = ictxt1 }
    return (hsc_env1, if result_ok then result_name:names else names, span, decl)
   where
@@ -996,8 +996,12 @@ moduleIsBootOrNotObjectLinkable mod_summary = withSession $ \hsc_env ->
 -- RTTI primitives
 
 obtainTermFromVal :: HscEnv -> Int -> Bool -> Type -> a -> IO Term
-obtainTermFromVal hsc_env bound force ty x =
-              cvObtainTerm hsc_env bound force ty (unsafeCoerce# x)
+obtainTermFromVal hsc_env bound force ty x
+  | gopt Opt_ExternalInterpreter (hsc_dflags hsc_env)
+  = throwIO (InstallationError
+      "obtainTermFromVal: this operation requires -fno-external-interpreter")
+  | otherwise
+  = cvObtainTerm hsc_env bound force ty (unsafeCoerce# x)
 
 obtainTermFromId :: HscEnv -> Int -> Bool -> Id -> IO Term
 obtainTermFromId hsc_env bound force id =  do
diff --git a/compiler/main/Packages.hs b/compiler/main/Packages.hs
index fa2db1964e..9068a3dd6d 100644
--- a/compiler/main/Packages.hs
+++ b/compiler/main/Packages.hs
@@ -82,7 +82,7 @@ import Maybes
 
 import System.Environment ( getEnv )
 import FastString
-import ErrUtils         ( debugTraceMsg, MsgDoc, printInfoForUser )
+import ErrUtils         ( debugTraceMsg, MsgDoc, printInfoForUser, dumpIfSet )
 import Exception
 
 import System.Directory
@@ -102,6 +102,8 @@ import qualified Data.Map.Strict as MapStrict
 import qualified Data.Set as Set
 import Data.Version
 
+import Debug.Trace (traceShowId)
+
 -- ---------------------------------------------------------------------------
 -- The Package state
 
@@ -467,6 +469,7 @@ listPackageConfigMap dflags = eltsUDFM pkg_map
 -- link in.
 initPackages :: DynFlags -> IO (DynFlags, [PreloadUnitId])
 initPackages dflags0 = do
+  putStrLn "[initPackages]"
   dflags <- interpretPackageEnv dflags0
   pkg_db <-
     case pkgDatabase dflags of
@@ -475,11 +478,26 @@ initPackages dflags0 = do
                                     -> (p, setBatchPackageFlags dflags pkgs)) db
   (pkg_state, preload, insts)
         <- mkPackageState dflags pkg_db []
+
+  dumpPkgState dflags pkg_state
+
+  putStrLn "[/initPackages]"
   return (dflags{ pkgDatabase = Just pkg_db,
                   pkgState = pkg_state,
                   thisUnitIdInsts_ = insts },
           preload)
 
+dumpPkgState :: DynFlags -> PackageState -> IO ()
+dumpPkgState dflags pkgState =
+  let pkgs = map snd . udfmToList . unPackageConfigMap . pkgIdMap $ pkgState
+  in dumpIfSet dflags True "Package State" $ vcat (map pprPkg pkgs)
+
+  where
+    pprPkg :: PackageConfig -> SDoc
+    pprPkg pkg = ppr (packageName pkg) <+> ppr (unitId pkg)
+                 $+$ nest 2 (fsep (map ppr (depends pkg)))
+
+
 -- -----------------------------------------------------------------------------
 -- Reading the package database(s)
 
@@ -524,8 +542,12 @@ getPackageConfRefs dflags = do
   isNotGlobal GlobalPkgConf = False
   isNotGlobal _ = True
 
-resolvePackageConfig :: DynFlags -> PkgConfRef -> IO (Maybe FilePath)
-resolvePackageConfig dflags GlobalPkgConf = return $ Just (systemPackageConfig dflags)
+targetPrefix, hostPrefix :: DynFlags -> String
+targetPrefix dflags = ""
+hostPrefix dflags = "x86_64-apple-darwin"
+
+resolvePackageConfig :: DynFlags -> PkgConfRef -> IO (Maybe (String, FilePath))
+resolvePackageConfig dflags GlobalPkgConf = return $ Just (targetPrefix dflags, systemPackageConfig dflags)
 -- NB: This logic is reimplemented in Cabal, so if you change it,
 -- make sure you update Cabal.  (Or, better yet, dump it in the
 -- compiler info so Cabal can use the info.)
@@ -533,11 +555,12 @@ resolvePackageConfig dflags UserPkgConf = runMaybeT $ do
   dir <- versionedAppDir dflags
   let pkgconf = dir </> "package.conf.d"
   exist <- tryMaybeT $ doesDirectoryExist pkgconf
-  if exist then return pkgconf else mzero
-resolvePackageConfig _ (PkgConfFile name) = return $ Just name
+  if exist then return (targetPrefix dflags, pkgconf) else mzero
+resolvePackageConfig dflags (PkgConfFile name) = return $ Just (targetPrefix dflags, name)
+resolvePackageConfig dflags (HostPkgConfFile name) = return $ Just (hostPrefix dflags, name)
 
-readPackageConfig :: DynFlags -> FilePath -> IO (FilePath, [PackageConfig])
-readPackageConfig dflags conf_file = do
+readPackageConfig :: DynFlags -> (String, FilePath) -> IO (FilePath, [PackageConfig])
+readPackageConfig dflags (prefix, conf_file) = do
   isdir <- doesDirectoryExist conf_file
 
   proto_pkg_configs <-
@@ -563,7 +586,8 @@ readPackageConfig dflags conf_file = do
       pkgroot = takeDirectory conf_file
       pkg_configs1 = map (mungePackageConfig top_dir pkgroot)
                          proto_pkg_configs
-      pkg_configs2 = setBatchPackageFlags dflags pkg_configs1
+      pkg_configs2 = setPackagePrefix dflags prefix
+                   $ setBatchPackageFlags dflags pkg_configs1
   --
   return (conf_file, pkg_configs2)
   where
@@ -617,6 +641,17 @@ readPackageConfig dflags conf_file = do
              else return (Just []) -- ghc-pkg will create it when it's updated
         else return Nothing
 
+setPackagePrefix :: DynFlags -> String -> [PackageConfig] -> [PackageConfig]
+setPackagePrefix dflags "" pkgs = pkgs
+setPackagePrefix dflags prefix pkgs = map go pkgs
+  where go pkg = pkg
+          { unitId = addPrefix (unitId pkg)
+          , packageName = y (packageName pkg)
+          , depends = map addPrefix (depends pkg)
+          }
+        addPrefix = stringToInstalledUnitId . ((prefix ++ "-") ++) . installedUnitIdString
+        y (PackageName fs) = PackageName $ (fsLit (prefix ++ "-")) Semigroup.<> fs
+
 setBatchPackageFlags :: DynFlags -> [PackageConfig] -> [PackageConfig]
 setBatchPackageFlags dflags pkgs = maybeDistrustAll pkgs
   where
@@ -976,12 +1011,16 @@ findWiredInPackages dflags prec_map pkgs vis_map = do
   -- their canonical names (eg. base-1.0 ==> base), as described
   -- in Note [Wired-in packages] in Module
   let
+        targetPrefix = case targetPlatformString dflags of
+          "" -> ""
+          pfx -> pfx ++ "-"
+
         matches :: PackageConfig -> WiredInUnitId -> Bool
         pc `matches` pid
             -- See Note [The integer library] in PrelNames
             | pid == unitIdString integerUnitId
             = packageNameString pc `elem` ["integer-gmp", "integer-simple"]
-        pc `matches` pid = packageNameString pc == pid
+        pc `matches` pid = packageNameString pc == traceShowId (targetPrefix ++ pid)
 
         -- find which package corresponds to each wired-in package
         -- delete any other packages with the same name
@@ -1993,7 +2032,9 @@ getPreloadPackagesAnd dflags pkgids0 =
       preload = preloadPackages state
       pairs = zip pkgids (repeat Nothing)
   in do
+  putStrLn $ "[getPreloadPackagesAnd] pkgids0 = " ++ show pkgids0
   all_pkgs <- throwErr dflags (foldM (add_package dflags pkg_map) preload pairs)
+  putStrLn $ "[getPreloadPacakgesAnd] all_pkgs = " ++ show all_pkgs
   return (map (getInstalledPackageDetails dflags) all_pkgs)
 
 -- Takes a list of packages, and returns the list with dependencies included,
diff --git a/compiler/main/SysTools.hs b/compiler/main/SysTools.hs
index d987d7dcd0..a63ae25195 100644
--- a/compiler/main/SysTools.hs
+++ b/compiler/main/SysTools.hs
@@ -8,7 +8,7 @@
 -----------------------------------------------------------------------------
 -}
 
-{-# LANGUAGE CPP, MultiWayIf, ScopedTypeVariables #-}
+{-# LANGUAGE CPP, MultiWayIf, ScopedTypeVariables, LambdaCase #-}
 
 module SysTools (
         -- * Initialisation
@@ -266,8 +266,13 @@ initSysTools mbMinusB
        lcc_prog <- getSetting "LLVM clang command"
 
        let iserv_prog = libexec "ghc-iserv"
+       integer_library <- getSetting "integer library" >>= \case
+         "gmp" -> pure IntegerGMP
+         "simple" -> pure IntegerSimple
+         x -> error $ "Unknown integer-library: " ++ x
 
        let platform = Platform {
+                          platformIntegerLibrary = integer_library,
                           platformArch = targetArch,
                           platformOS   = targetOS,
                           platformWordSize = targetWordSize,
@@ -275,7 +280,8 @@ initSysTools mbMinusB
                           platformHasGnuNonexecStack = targetHasGnuNonexecStack,
                           platformHasIdentDirective = targetHasIdentDirective,
                           platformHasSubsectionsViaSymbols = targetHasSubsectionsViaSymbols,
-                          platformIsCrossCompiling = crossCompiling
+                          platformIsCrossCompiling = crossCompiling,
+                          platformString = ""
                       }
 
        return $ Settings {
diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs
index d461b99c43..a73e7f3f41 100644
--- a/compiler/simplCore/SimplCore.hs
+++ b/compiler/simplCore/SimplCore.hs
@@ -462,11 +462,7 @@ doCorePass (CoreDoRuleCheck phase pat)  = ruleCheckPass phase pat
 doCorePass CoreDoNothing                = return
 doCorePass (CoreDoPasses passes)        = runCorePasses passes
 
-#if defined(GHCI)
 doCorePass (CoreDoPluginPass _ pass) = {-# SCC "Plugin" #-} pass
-#else
-doCorePass pass@CoreDoPluginPass {}  = pprPanic "doCorePass" (ppr pass)
-#endif
 
 doCorePass pass@CoreDesugar          = pprPanic "doCorePass" (ppr pass)
 doCorePass pass@CoreDesugarOpt       = pprPanic "doCorePass" (ppr pass)
diff --git a/compiler/utils/Platform.hs b/compiler/utils/Platform.hs
index 449a62a5b6..179449c603 100644
--- a/compiler/utils/Platform.hs
+++ b/compiler/utils/Platform.hs
@@ -9,6 +9,7 @@ module Platform (
         ArmISAExt(..),
         ArmABI(..),
         PPC_64ABI(..),
+        IntegerLibrary(..),
 
         target32Bit,
         isARM,
@@ -26,6 +27,7 @@ import GhcPrelude
 --      code for this platform.
 data Platform
         = Platform {
+              platformIntegerLibrary           :: IntegerLibrary,
               platformArch                     :: Arch,
               platformOS                       :: OS,
               -- Word size in bytes (i.e. normally 4 or 8,
@@ -35,10 +37,15 @@ data Platform
               platformHasGnuNonexecStack       :: Bool,
               platformHasIdentDirective        :: Bool,
               platformHasSubsectionsViaSymbols :: Bool,
-              platformIsCrossCompiling         :: Bool
+              platformIsCrossCompiling         :: Bool,
+              platformString                   :: String
           }
         deriving (Read, Show, Eq)
 
+data IntegerLibrary = IntegerGMP
+                    | IntegerSimple
+                    deriving (Read, Show, Eq)
+
 
 -- | Architectures that the native code generator knows about.
 --      TODO: It might be nice to extend these constructors with information
@@ -159,4 +166,3 @@ platformUsesFrameworks = osUsesFrameworks . platformOS
 osSubsectionsViaSymbols :: OS -> Bool
 osSubsectionsViaSymbols OSDarwin = True
 osSubsectionsViaSymbols _        = False
-
diff --git a/configure.ac b/configure.ac
index 11c2a3400f..91ca917b1e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -988,6 +988,13 @@ dnl ################################################################
 dnl Check for libraries
 dnl ################################################################
 
+# integer lib
+AC_ARG_WITH([integer-library],[AC_HELP_STRING([--with-integer-library],[Integer library to use [default=gmp]])])
+AS_IF([test "x$with_integer_library" = "x"],
+      [SettingsIntegerLibrary="gmp"],
+      [SettingsIntegerLibrary="$with_integer_library"])
+AC_SUBST(SettingsIntegerLibrary)
+
 # system libffi
 
 AC_ARG_WITH([system-libffi],
diff --git a/ghc/Main.hs b/ghc/Main.hs
index eda6a3d2a1..162b2176fd 100644
--- a/ghc/Main.hs
+++ b/ghc/Main.hs
@@ -30,12 +30,10 @@ import GHCi.UI          ( interactiveUI, ghciWelcomeMsg, defaultGhciSettings )
 #endif
 
 -- Frontend plugins
-#if defined(GHCI)
+
 import DynamicLoading   ( loadFrontendPlugin )
 import Plugins
-#else
-import DynamicLoading   ( pluginError )
-#endif
+
 import Module           ( ModuleName )
 
 
@@ -834,15 +832,11 @@ dumpPackagesSimple dflags = putMsg dflags (pprPackagesSimple dflags)
 -- Frontend plugin support
 
 doFrontend :: ModuleName -> [(String, Maybe Phase)] -> Ghc ()
-#if !defined(GHCI)
-doFrontend modname _ = pluginError [modname]
-#else
 doFrontend modname srcs = do
     hsc_env <- getSession
     frontend_plugin <- liftIO $ loadFrontendPlugin hsc_env modname
     frontend frontend_plugin
       (reverse $ frontendPluginOpts (hsc_dflags hsc_env)) srcs
-#endif
 
 -- -----------------------------------------------------------------------------
 -- ABI hash support
diff --git a/libraries/ghci/GHCi/BreakArray.hs b/libraries/ghci/GHCi/BreakArray.hs
index bece43bdb9..f645fa95b3 100644
--- a/libraries/ghci/GHCi/BreakArray.hs
+++ b/libraries/ghci/GHCi/BreakArray.hs
@@ -15,7 +15,7 @@
 --   0 otherwise
 --
 -------------------------------------------------------------------------------
-
+#define GHCI
 module GHCi.BreakArray
     (
       BreakArray
diff --git a/libraries/ghci/GHCi/InfoTable.hsc b/libraries/ghci/GHCi/InfoTable.hsc
index ca5757257c..c4b554bc73 100644
--- a/libraries/ghci/GHCi/InfoTable.hsc
+++ b/libraries/ghci/GHCi/InfoTable.hsc
@@ -3,6 +3,7 @@
 -- Get definitions for the structs, constants & config etc.
 #include "Rts.h"
 
+#define GHCI
 -- |
 -- Run-time info table support.  This module provides support for
 -- creating and reading info tables /in the running program/.
diff --git a/libraries/ghci/ghci.cabal.in b/libraries/ghci/ghci.cabal.in
index 32ce79c013..0171cde829 100644
--- a/libraries/ghci/ghci.cabal.in
+++ b/libraries/ghci/ghci.cabal.in
@@ -48,12 +48,6 @@ library
 
     if flag(ghci)
         CPP-Options: -DGHCI
-        exposed-modules:
-            GHCi.Run
-            GHCi.CreateBCO
-            GHCi.ObjLink
-            GHCi.Signals
-            GHCi.TH
 
     exposed-modules:
         GHCi.BreakArray
@@ -66,6 +60,11 @@ library
         GHCi.StaticPtrTable
         GHCi.TH.Binary
         SizedSeq
+            GHCi.Run
+            GHCi.CreateBCO
+            GHCi.ObjLink
+            GHCi.Signals
+            GHCi.TH
 
     Build-Depends:
         array            == 0.5.*,
diff --git a/settings.in b/settings.in
index 30bfe7072b..019d360189 100644
--- a/settings.in
+++ b/settings.in
@@ -31,6 +31,6 @@
  ("Unregisterised", "@Unregisterised@"),
  ("LLVM llc command", "@SettingsLlcCommand@"),
  ("LLVM opt command", "@SettingsOptCommand@"),
- ("LLVM clang command", "@SettingsClangCommand@")
+ ("LLVM clang command", "@SettingsClangCommand@"),
+ ("integer library", "@SettingsIntegerLibrary@")
  ]
-