Abort the build when a Core plugin pass is specified in stage1 compiler

This also makes the behavior the same with frontend plugin errors --
frontend was failing with an exception (`CmdLineError`) while the
simplifier was just ignoring plugins. Now we abort with `CmdLineError`
in both cases with a slightly improved error message.

Test Plan:
- add tests (will add tests once #12197 is implemented)
- validate (done)

Reviewers: austin, bgamari

Subscribers: thomie

Differential Revision: https://phabricator.haskell.org/D2334

GHC Trac Issues: #11690

3 files changed, 33 insertions, 3 deletions

diff --git a/compiler/main/DynamicLoading.hs b/compiler/main/DynamicLoading.hs
index e7a2b95..2b2365f 100644
--- a/compiler/main/DynamicLoading.hs
+++ b/compiler/main/DynamicLoading.hs
@@ -19,6 +19,8 @@ module DynamicLoading (
         getValueSafely,
         getHValueSafely,
         lessUnsafeCoerce
+#else
+        pluginError,
 #endif
     ) where
 
@@ -55,6 +57,16 @@ import Hooks
 import Data.Maybe        ( mapMaybe )
 import GHC.Exts          ( unsafeCoerce# )
 
+#else
+
+import Module           ( ModuleName, moduleNameString )
+import Panic
+
+import Data.List        ( intercalate )
+
+#endif
+
+#ifdef GHCI
 
 loadPlugins :: HscEnv -> IO [(ModuleName, Plugin, [CommandLineOption])]
 loadPlugins hsc_env
@@ -243,4 +255,15 @@ throwCmdLineErrorS dflags = throwCmdLineError . showSDoc dflags
 
 throwCmdLineError :: String -> IO a
 throwCmdLineError = throwGhcExceptionIO . CmdLineError
+
+#else
+
+pluginError :: [ModuleName] -> a
+pluginError modnames = throwGhcException (CmdLineError msg)
+  where
+    msg = "not built for interactive use - can't load plugins ("
+            -- module names are not z-encoded
+          ++ intercalate ", " (map moduleNameString modnames)
+          ++ ")"
+
 #endif
diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs
index 6884696..85ae8cd 100644
--- a/compiler/simplCore/SimplCore.hs
+++ b/compiler/simplCore/SimplCore.hs
@@ -59,6 +59,8 @@ import qualified GHC.LanguageExtensions as LangExt
 #ifdef GHCI
 import DynamicLoading   ( loadPlugins )
 import Plugins          ( installCoreToDos )
+#else
+import DynamicLoading   ( pluginError )
 #endif
 
 {-
@@ -350,7 +352,11 @@ getCoreToDo dflags
 
 addPluginPasses :: [CoreToDo] -> CoreM [CoreToDo]
 #ifndef GHCI
-addPluginPasses builtin_passes = return builtin_passes
+addPluginPasses builtin_passes
+  = do { dflags <- getDynFlags
+       ; let pluginMods = pluginModNames dflags
+       ; unless (null pluginMods) (pluginError pluginMods)
+       ; return builtin_passes }
 #else
 addPluginPasses builtin_passes
   = do { hsc_env <- getHscEnv
diff --git a/ghc/Main.hs b/ghc/Main.hs
index 5605438..1a6cbeb 100644
--- a/ghc/Main.hs
+++ b/ghc/Main.hs
@@ -32,6 +32,8 @@ import GHCi.UI          ( interactiveUI, ghciWelcomeMsg, defaultGhciSettings )
 #ifdef GHCI
 import DynamicLoading
 import Plugins
+#else
+import DynamicLoading   ( pluginError )
 #endif
 import Module           ( ModuleName )
 
@@ -841,8 +843,7 @@ dumpPackagesSimple dflags = putMsg dflags (pprPackagesSimple dflags)
 
 doFrontend :: ModuleName -> [(String, Maybe Phase)] -> Ghc ()
 #ifndef GHCI
-doFrontend _ _ =
-    throwGhcException (CmdLineError "not built for interactive use")
+doFrontend modname _ = pluginError [modname]
 #else
 doFrontend modname srcs = do
     hsc_env <- getSession