Merge branch 'master' into release

Language/Haskell/GhcMod/Utils.hs

@@ -1,11 +1,17 @@
+{-# LANGUAGE CPP #-}
 module Language.Haskell.GhcMod.Utils where
 
-
+import Control.Applicative ((<$>))
 import Language.Haskell.GhcMod.Error
 import MonadUtils (MonadIO, liftIO)
 import System.Directory (getCurrentDirectory, setCurrentDirectory)
 import System.Exit (ExitCode(..))
 import System.Process (readProcessWithExitCode)
+import System.FilePath (takeDirectory)
+import System.Environment
+#ifndef SPEC
+import System.FilePath ((</>))
+#endif
 
 -- dropWhileEnd is not provided prior to base 4.5.0.0.
 dropWhileEnd :: (a -> Bool) -> [a] -> [a]
@@ -42,3 +48,23 @@ withDirectory_ :: (MonadIO m, ExceptionMonad m) => FilePath -> m a -> m a
 withDirectory_ dir action =
     gbracket (liftIO getCurrentDirectory) (liftIO . setCurrentDirectory)
                 (\_ -> liftIO (setCurrentDirectory dir) >> action)
+
+-- | Returns the path to the currently running ghc-mod executable. With ghc<7.6
+-- this is a guess but >=7.6 uses 'getExecutablePath'.
+ghcModExecutable :: IO FilePath
+#ifndef SPEC
+ghcModExecutable = do
+    dir <- getExecutablePath'
+    return $ dir </> "ghc-mod"
+#else
+ghcModExecutable = do _ <- getExecutablePath' -- get rid of unused warning when
+                                              -- compiling spec
+                      return "dist/build/ghc-mod/ghc-mod"
+#endif
+ where
+    getExecutablePath' :: IO FilePath
+# if __GLASGOW_HASKELL__ >= 706
+    getExecutablePath' = takeDirectory <$> getExecutablePath
+# else
+    getExecutablePath' = return ""
+# endif