Also enable and test MagicHash

Author: googleson78

example/package-a/app/Main.hs

@@ -1,16 +1,20 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE PatternSynonyms #-}
 {-# LANGUAGE ExplicitNamespaces #-}
+{-# LANGUAGE MagicHash #-}
 module Main where
 
 #define a_multiline macro \
   a second line of the macro
 import NonModulesLib (nonModulesLib)
 import PackageA.Other.C(type DataC, DataC(DataC), pattern PatTrue)
+import GHC.Exts (Int(..), Int#)
 
 main :: IO ()
 main = do
   let
     dataC :: DataC
     dataC = DataC PatTrue
-  putStrLn $ "Hello, Haskell! " ++ show nonModulesLib ++ show dataC
+    int# :: Int#
+    int# = case 1 of I# i -> i
+  putStrLn $ "Hello, Haskell! " ++ show nonModulesLib ++ show dataC ++ show (I# int#)

himportscan/src/HImportScan/GHC.hs

@@ -14,6 +14,7 @@ import GHC.LanguageExtensions as X
     , ImplicitPrelude
     , PatternSynonyms
     , ExplicitNamespaces
+    , MagicHash
     )
   )
 import HeaderInfo as X (getOptions, getImports)

himportscan/src/HImportScan/ImportScanner.hs

@@ -128,6 +128,7 @@ toggleDynFlags dflags0 =
                   , GHC.TemplateHaskell
                   , GHC.PatternSynonyms
                   , GHC.ExplicitNamespaces
+                  , GHC.MagicHash
                   ]
    in GHC.xopt_unset dflags1 GHC.ImplicitPrelude