From 982c4ee684bf2d0be38a8709433b69110a10a91c Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Thu, 18 Mar 2021 15:30:31 +0000
Subject: [PATCH] Avoid duplicating known targets and import paths (#1590)

---
 ghcide/session-loader/Development/IDE/Session.hs |  5 +++--
 ghcide/src/Development/IDE/Types/HscEnvEq.hs     | 10 ++++++----
 ghcide/src/Development/IDE/Types/KnownTargets.hs |  4 ++--
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/ghcide/session-loader/Development/IDE/Session.hs b/ghcide/session-loader/Development/IDE/Session.hs
index 9f023bb947..0b9386ec70 100644
--- a/ghcide/session-loader/Development/IDE/Session.hs
+++ b/ghcide/session-loader/Development/IDE/Session.hs
@@ -83,6 +83,7 @@ import           Packages
 
 import           Control.Concurrent.STM               (atomically)
 import           Control.Concurrent.STM.TQueue
+import qualified Data.HashSet                         as Set
 import           Database.SQLite.Simple
 import           HIE.Bios.Cradle                      (yamlConfig)
 import           HieDb.Create
@@ -247,10 +248,10 @@ loadSessionWithOptions SessionLoadingOptions{..} dir = do
                 found <- filterM (IO.doesFileExist . fromNormalizedFilePath) targetLocations
                 return (targetTarget, found)
           modifyVarIO' knownTargetsVar $ traverseHashed $ \known -> do
-            let known' = HM.unionWith (<>) known $ HM.fromList knownTargets
+            let known' = HM.unionWith (<>) known $ HM.fromList $ map (second Set.fromList) knownTargets
             when (known /= known') $
                 logDebug logger $ "Known files updated: " <>
-                    T.pack(show $ (HM.map . map) fromNormalizedFilePath known')
+                    T.pack(show $ (HM.map . Set.map) fromNormalizedFilePath known')
             pure known'
 
     -- Create a new HscEnv from a hieYaml root and a set of options
diff --git a/ghcide/src/Development/IDE/Types/HscEnvEq.hs b/ghcide/src/Development/IDE/Types/HscEnvEq.hs
index 2395fc08e6..38338f4b49 100644
--- a/ghcide/src/Development/IDE/Types/HscEnvEq.hs
+++ b/ghcide/src/Development/IDE/Types/HscEnvEq.hs
@@ -18,6 +18,8 @@ import           Control.Exception             (evaluate, mask, throwIO)
 import           Control.Monad.Extra           (eitherM, join, mapMaybeM)
 import           Control.Monad.IO.Class
 import           Data.Either                   (fromRight)
+import           Data.Set                      (Set)
+import qualified Data.Set                      as Set
 import           Data.Unique
 import           Development.IDE.GHC.Compat
 import           Development.IDE.GHC.Error     (catchSrcErrors)
@@ -48,7 +50,7 @@ data HscEnvEq = HscEnvEq
                -- ^ In memory components for this HscEnv
                -- This is only used at the moment for the import dirs in
                -- the DynFlags
-    , envImportPaths        :: Maybe [String]
+    , envImportPaths        :: Maybe (Set FilePath)
         -- ^ If Just, import dirs originally configured in this env
         --   If Nothing, the env import dirs are unaltered
     , envPackageExports     :: IO ExportsMap
@@ -69,9 +71,9 @@ newHscEnvEq cradlePath hscEnv0 deps = do
     importPathsCanon <-
       mapM canonicalizePath $ relativeToCradle <$> importPaths (hsc_dflags hscEnv0)
 
-    newHscEnvEqWithImportPaths (Just importPathsCanon) hscEnv deps
+    newHscEnvEqWithImportPaths (Just $ Set.fromList importPathsCanon) hscEnv deps
 
-newHscEnvEqWithImportPaths :: Maybe [String] -> HscEnv -> [(InstalledUnitId, DynFlags)] -> IO HscEnvEq
+newHscEnvEqWithImportPaths :: Maybe (Set FilePath) -> HscEnv -> [(InstalledUnitId, DynFlags)] -> IO HscEnvEq
 newHscEnvEqWithImportPaths envImportPaths hscEnv deps = do
 
     let dflags = hsc_dflags hscEnv
@@ -121,7 +123,7 @@ newHscEnvEqPreserveImportPaths = newHscEnvEqWithImportPaths Nothing
 hscEnvWithImportPaths :: HscEnvEq -> HscEnv
 hscEnvWithImportPaths HscEnvEq{..}
     | Just imps <- envImportPaths
-    = hscEnv{hsc_dflags = (hsc_dflags hscEnv){importPaths = imps}}
+    = hscEnv{hsc_dflags = (hsc_dflags hscEnv){importPaths = Set.toList imps}}
     | otherwise
     = hscEnv
 
diff --git a/ghcide/src/Development/IDE/Types/KnownTargets.hs b/ghcide/src/Development/IDE/Types/KnownTargets.hs
index 86cc887260..7ec2e493a5 100644
--- a/ghcide/src/Development/IDE/Types/KnownTargets.hs
+++ b/ghcide/src/Development/IDE/Types/KnownTargets.hs
@@ -14,11 +14,11 @@ import           Development.IDE.Types.Location
 import           GHC.Generics
 
 -- | A mapping of module name to known files
-type KnownTargets = HashMap Target [NormalizedFilePath]
+type KnownTargets = HashMap Target (HashSet NormalizedFilePath)
 
 data Target = TargetModule ModuleName | TargetFile NormalizedFilePath
   deriving ( Eq, Generic, Show )
   deriving anyclass (Hashable, NFData)
 
 toKnownFiles :: KnownTargets -> HashSet NormalizedFilePath
-toKnownFiles = HSet.fromList . concat . HMap.elems
+toKnownFiles = HSet.unions . HMap.elems