add test for late plugins

testsuite/tests/plugins/Makefile

@@ -224,3 +224,13 @@ plugins-external:
 	cp shared-plugin/pkg.plugins01/dist/build/$(call DLL,HSsimple-plugin*) $(call DLL,HSsimple-plugin)
 	"$(TEST_HC)" $(TEST_HC_OPTS) $(ghcPluginWayFlags) --make -v0 -fplugin-library "$(PWD)/$(call DLL,HSsimple-plugin);simple-plugin-1234;Simple.Plugin;[\"Plugin\",\"loaded\",\"from\",\"a shared lib\"]" plugins-external.hs
 	./plugins-external
+
+# Runs a plugin that is both a core plugin and a late plugin, then makes sure
+# only the changes from the core plugin end up in the interface files.
+test-late-plugin:
+	"$(TEST_HC)" $(TEST_HC_OPTS) $(ghcPluginWayFlags) -O -package ghc $@.hs
+	SHOW_IFACE="$$($(TEST_HC) --show-iface $@.hi)" ; \
+	ContainsEarlyBinding=$$(echo $$SHOW_IFACE | grep -o 111111) ; \
+	ContainsLateBinding=$$(echo $$SHOW_IFACE | grep -o 222222) ; \
+	echo "$$ContainsLateBinding" ; \
+	[ "$$ContainsEarlyBinding" = "111111" ] && [ "$$ContainLateBinding" = "" ]

testsuite/tests/plugins/all.T

@@ -358,3 +358,8 @@ test('test-log-hooks-plugin',
       pre_cmd('$MAKE -s --no-print-directory -C hooks-plugin package.test-log-hooks-plugin TOP={top}')],
      compile_fail,
      ['-package-db hooks-plugin/pkg.test-log-hooks-plugin/local.package.conf -fplugin Hooks.LogPlugin -package hooks-plugin ' + config.plugin_way_flags])
+
+test('test-late-plugin',
+     [extra_files(['late-plugin/LatePlugin.hs']), ignore_stdout],
+     makefile_test,
+     [])

testsuite/tests/plugins/late-plugin/LatePlugin.hs

+module LatePlugin where
+
+import Data.Bool
+import GHC.Core
+import GHC.Driver.Monad
+import GHC.Plugins
+import GHC.Types.Avail
+import GHC.Types.Var
+import GHC.Types.Id
+import System.IO
+
+-- | Both a core plugin and a late plugin. The Core plugin edits the binding in
+-- the test file (testBinding) to be the integer "111111". The late plugin then
+-- edits the binding to be the integer "222222". Then we make sure the "222222"
+-- did not make it in the interface file and the "111111" did.
+plugin :: Plugin
+plugin =
+    defaultPlugin
+      { installCoreToDos = earlyP
+      , latePlugin = lateP
+      }
+
+earlyP :: CorePlugin
+earlyP _ todos = do
+    return
+      . (: todos)
+      $ CoreDoPluginPass "earlyP"
+      $ \mgs -> liftIO $ do
+          binds' <- editCoreBinding True (moduleName (mg_module mgs)) (mg_binds mgs)
+          return mgs { mg_binds = binds' }
+
+lateP :: LatePlugin
+lateP _ opts (cg_guts, cc_state) = do
+  binds' <- editCoreBinding False (moduleName (cg_module cg_guts)) (cg_binds cg_guts)
+  return (cg_guts { cg_binds = binds' }, cc_state)
+
+editCoreBinding :: Bool -> ModuleName -> CoreProgram -> IO CoreProgram
+editCoreBinding early modName pgm = do
+    putStrLn $
+      bool "late " "early " early ++ "plugin running on module " ++
+      moduleNameString modName
+    pure $ go pgm
+  where
+    go :: [CoreBind] -> [CoreBind]
+    go (b@(NonRec v e) : bs)
+      | occNameString (getOccName v) == "testBinding" =
+          NonRec v (mkUncheckedIntExpr $ bool 222222 111111 early) : bs
+    go (b:bs) = b : go bs
+    go [] = []

testsuite/tests/plugins/test-late-plugin.hs

+{-# LANGUAGE MagicHash #-}
+{-# OPTIONS_GHC -fplugin=LatePlugin #-}
+
+module TestLatePlugin (testBinding) where
+
+import GHC.Exts
+
+-- This file is edited by a core plugin at the beginning of the core pipeline so
+-- that the value of testBinding becomes 111111. Then, a late plugin edits the
+-- binding to set testBinding to 222222. The test then checks that the early
+-- binding value is what makes it into the interface file, just to be sure that
+-- changes from late plugins do not end up in interface files.
+
+testBinding :: Int
+testBinding = -1