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

1 files changed, 7 insertions, 1 deletions

diff --git a/compiler/simplCore/SimplCore.hs b/compiler/simplCore/SimplCore.hs
index 6884696c97..85ae8cda89 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