Actually update `world` in legacyInteractiveLoop

Language/Haskell/GhcMod/Target.hs

@@ -69,8 +69,13 @@ initSession :: IOish m
 initSession opts mdf = do
    s <- gmsGet
    case gmGhcSession s of
-     Just GmGhcSession {..} -> when (gmgsOptions /= opts) $ putNewSession s
-     Nothing -> putNewSession s
+     Just GmGhcSession {..} | gmgsOptions /= opts-> do
+         gmLog GmDebug "initSession" $ text "Flags changed, creating new session"
+         putNewSession s
+     Just _ -> return ()
+     Nothing -> do
+         gmLog GmDebug "initSession" $ text "Session not initialized, creating new one"
+         putNewSession s
 
  where
    putNewSession s = do

src/GHCMod.hs

@@ -462,6 +462,11 @@ legacyInteractiveLoop symdbreq world = do
     -- after blocking, we need to see if the world has changed.
 
     changed <- didWorldChange world
+
+    world' <- if changed
+                then getCurrentWorld -- TODO: gah, we're hitting the fs twice
+                else return world
+
     when changed $ do
         dropSession
 
@@ -500,7 +505,7 @@ legacyInteractiveLoop symdbreq world = do
         _        -> fatalError $ "unknown command: `" ++ cmd ++ "'"
 
     gmPutStr res >> gmPutStrLn "OK" >> liftIO (hFlush stdout)
-    legacyInteractiveLoop symdbreq world
+    legacyInteractiveLoop symdbreq world'
  where
    interactiveHandlers =
           [ GHandler $ \e@(FatalError _) -> throw e