Preserve envImportPaths in GhcSessionDeps (#862)

Author: pepeiborra

src/Development/IDE/Core/Rules.hs

@@ -665,7 +665,8 @@ loadGhcSession = do
 
 ghcSessionDepsDefinition :: NormalizedFilePath -> Action (IdeResult HscEnvEq)
 ghcSessionDepsDefinition file = do
-        hsc <- hscEnv <$> use_ GhcSession file
+        env <- use_ GhcSession file
+        let hsc = hscEnv env
         (deps,_) <- useWithStale_ GetDependencies file
         let tdeps = transitiveModuleDeps deps
         ifaces <- uses_ GetModIface tdeps
@@ -679,7 +680,7 @@ ghcSessionDepsDefinition file = do
             setupFinderCache (map hirModSummary ifaces)
             mapM_ loadDepModule inLoadOrder
 
-        res <- liftIO $ newHscEnvEq "" session' []
+        res <- liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
         return ([], Just res)
 
 getModIfaceFromDiskRule :: Rules ()

src/Development/IDE/GHC/Util.hs

@@ -31,7 +31,8 @@ module Development.IDE.GHC.Util(
     setHieDir,
     dontWriteHieFiles,
     disableWarningsAsErrors,
-    newHscEnvEqPreserveImportPaths) where
+    newHscEnvEqPreserveImportPaths,
+    newHscEnvEqWithImportPaths) where
 
 import Control.Concurrent
 import Data.List.Extra
@@ -193,6 +194,11 @@ newHscEnvEq cradlePath hscEnv0 deps = do
         hscEnv = removeImportPaths hscEnv0
     return HscEnvEq{..}
 
+newHscEnvEqWithImportPaths :: Maybe [String] -> HscEnv -> [(InstalledUnitId, DynFlags)] -> IO HscEnvEq
+newHscEnvEqWithImportPaths envImportPaths hscEnv deps = do
+    envUnique <- newUnique
+    return HscEnvEq{..}
+
 -- | Wrap an 'HscEnv' into an 'HscEnvEq'.
 newHscEnvEqPreserveImportPaths
     :: HscEnv -> [(InstalledUnitId, DynFlags)] -> IO HscEnvEq