Always enable the external interpreter

You can always just not use or even build `iserv`. I don't think the
maintenance cost of the CPP is worth...I can't even tell what the
benefit is.

2 files changed, 31 insertions, 25 deletions

diff --git a/ghc/Main.hs b/ghc/Main.hs
index d53c71a779..4cdf3ecb94 100644
--- a/ghc/Main.hs
+++ b/ghc/Main.hs
@@ -1,4 +1,7 @@
-{-# LANGUAGE CPP, NondecreasingIndentation, TupleSections #-}
+{-# LANGUAGE CPP #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE NondecreasingIndentation #-}
+{-# LANGUAGE TupleSections #-}
 {-# OPTIONS -fno-warn-incomplete-patterns -optc-DNON_POSIX_SOURCE #-}
 
 -----------------------------------------------------------------------------
@@ -30,12 +33,8 @@ import GHCi.UI          ( interactiveUI, ghciWelcomeMsg, defaultGhciSettings )
 #endif
 
 -- Frontend plugins
-#if defined(HAVE_INTERPRETER)
 import DynamicLoading   ( loadFrontendPlugin )
 import Plugins
-#else
-import DynamicLoading   ( pluginError )
-#endif
 #if defined(HAVE_INTERNAL_INTERPRETER)
 import DynamicLoading   ( initializePlugins )
 #endif
@@ -44,6 +43,8 @@ import Module           ( ModuleName )
 
 -- Various other random stuff that we need
 import GHC.HandleEncoding
+import GHC.Platform
+import GHC.Platform.Host
 import Config
 import Constants
 import HscTypes
@@ -54,6 +55,8 @@ import DynFlags hiding (WarnReason(..))
 import ErrUtils
 import FastString
 import Outputable
+import SysTools.BaseDir
+import SysTools.Settings
 import SrcLoc
 import Util
 import Panic
@@ -74,6 +77,8 @@ import System.Environment
 import System.Exit
 import System.FilePath
 import Control.Monad
+import Control.Monad.Trans.Class
+import Control.Monad.Trans.Except (throwE, runExceptT)
 import Data.Char
 import Data.List
 import Data.Maybe
@@ -122,7 +127,7 @@ main = do
     case mode of
         Left preStartupMode ->
             do case preStartupMode of
-                   ShowSupportedExtensions   -> showSupportedExtensions
+                   ShowSupportedExtensions   -> showSupportedExtensions mbMinusB
                    ShowVersion               -> showVersion
                    ShowNumVersion            -> putStrLn cProjectVersion
                    ShowOptions isInteractive -> showOptions isInteractive
@@ -776,8 +781,24 @@ showInfo dflags = do
         let sq x = " [" ++ x ++ "\n ]"
         putStrLn $ sq $ intercalate "\n ," $ map show $ compilerInfo dflags
 
-showSupportedExtensions :: IO ()
-showSupportedExtensions = mapM_ putStrLn supportedLanguagesAndExtensions
+-- TODO use ErrUtils once that is disentangled from all the other GhcMonad stuff?
+showSupportedExtensions :: Maybe String -> IO ()
+showSupportedExtensions m_top_dir = do
+  res <- runExceptT $ do
+    top_dir <- lift (tryFindTopDir m_top_dir) >>= \case
+      Nothing -> throwE $ SettingsError_MissingData "Could not find the top directory, missing -B flag"
+      Just dir -> pure dir
+    initSettings top_dir
+  targetPlatformMini <- case res of
+    Right s -> pure $ platformMini $ sTargetPlatform s
+    Left (SettingsError_MissingData msg) -> do
+      hPutStrLn stderr $ "WARNING: " ++ show msg
+      hPutStrLn stderr $ "cannot know target platform so guessing target == host (native compiler)."
+      pure cHostPlatformMini
+    Left (SettingsError_BadData msg) -> do
+      hPutStrLn stderr msg
+      exitWith $ ExitFailure 1
+  mapM_ putStrLn $ supportedLanguagesAndExtensions targetPlatformMini
 
 showVersion :: IO ()
 showVersion = putStrLn (cProjectName ++ ", version " ++ cProjectVersion)
@@ -847,15 +868,11 @@ dumpPackagesSimple dflags = putMsg dflags (pprPackagesSimple dflags)
 -- Frontend plugin support
 
 doFrontend :: ModuleName -> [(String, Maybe Phase)] -> Ghc ()
-#if !defined(HAVE_INTERPRETER)
-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/ghc/ghc-bin.cabal.in b/ghc/ghc-bin.cabal.in
index cf5fde03e3..721df4ea62 100644
--- a/ghc/ghc-bin.cabal.in
+++ b/ghc/ghc-bin.cabal.in
@@ -24,11 +24,6 @@ Flag ghci
     Default: False
     Manual: True
 
-Flag ext-interp
-    Description: Build external interpreter support
-    Default: True
-    Manual: True
-
 Flag threaded
     Description: Link the ghc executable against the threaded RTS
     Default: True
@@ -44,6 +39,7 @@ Executable ghc
                    directory  >= 1   && < 1.4,
                    process    >= 1   && < 1.7,
                    filepath   >= 1   && < 1.5,
+                   transformers == 0.5.*,
                    ghc-boot   == @ProjectVersionMunged@,
                    ghc        == @ProjectVersionMunged@
 
@@ -66,8 +62,7 @@ Executable ghc
             ghc-prim       >= 0.5.0 && < 0.7,
             ghci           == @ProjectVersionMunged@,
             haskeline      == 0.7.*,
-            time           >= 1.8 && < 1.10,
-            transformers   == 0.5.*
+            time           >= 1.8 && < 1.10
         CPP-Options: -DHAVE_INTERNAL_INTERPRETER
         GHC-Options: -fno-warn-name-shadowing
         Other-Modules:
@@ -97,12 +92,6 @@ Executable ghc
     if flag(threaded)
       ghc-options: -threaded
 
-    if flag(ext-interp)
-      cpp-options: -DHAVE_EXTERNAL_INTERPRETER
-
-    if flag(ghci) || flag(ext-interp)
-      cpp-options: -DHAVE_INTERPRETER
-
     Other-Extensions:
         CPP
         NondecreasingIndentation