From 5c8e9997a77d1794cd8d78687871cde8a6cd86f5 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 30 Oct 2021 19:28:44 +0100
Subject: [PATCH 01/17] Improve the performance of GetModIfaceFromDisk in large
 repos

There are three benefits:
1. GetModIfaceFromDisk and GhcSessionDeps no longer depend on the transitive module summaries. This means fewer edges in the build graph = smaller build graph = faster builds
2. Avoid duplicate computations in setting up the GHC session with the dependencies of the module. Previously the total work done was O(NlogN) in the number of transitive dependencies, now it is O(N).
3. Increased sharing of HPT and FinderCache. Ideally we should also
   share the module graphs, but the datatype is abstract, doesn't have a
   monoid instance, and cannot be coerced to something that has. We will
   need to add the Monoid instance in GHC first.

On the Sigma repo:
- the startup metric goes down by ~34%.
- The edit metric also goes down by 15%.
- Max residency is down by 30% in the edit benchmark.
---
 ghcide/src/Development/IDE/Core/Rules.hs | 73 +++++++++++++++++-------
 1 file changed, 53 insertions(+), 20 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 23fa70d3df..35a019aa26 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -150,6 +150,12 @@ import           Ide.PluginUtils                              (configForPlugin)
 import           Ide.Types                                    (DynFlagsModifications (dynFlagsModifyGlobal, dynFlagsModifyParser),
                                                                PluginId)
 import qualified Data.HashSet as HS
+import Unsafe.Coerce (unsafeCoerce)
+import Data.Map (Map)
+import GhcPlugins (FinderCache, mgModSummaries)
+import qualified Development.IDE.GHC.Compat as GHC
+import Development.IDE.GHC.Compat (installedModule)
+import Data.List.Extra (nubOrdOn)
 
 -- | This is useful for rules to convert rules that can only produce errors or
 -- a result into the more general IdeResult type that supports producing
@@ -691,49 +697,76 @@ loadGhcSession = do
                 Nothing -> LBS.toStrict $ B.encode (hash (snd val))
         return (Just cutoffHash, val)
 
-    define $ \GhcSessionDeps file -> ghcSessionDepsDefinition file
+    defineNoDiagnostics $ \GhcSessionDeps file -> Just <$> ghcSessionDepsDefinition file
 
-ghcSessionDepsDefinition :: NormalizedFilePath -> Action (IdeResult HscEnvEq)
+ghcSessionDepsDefinition :: NormalizedFilePath -> Action HscEnvEq
 ghcSessionDepsDefinition file = do
         env <- use_ GhcSession file
         let hsc = hscEnv env
         ms <- msrModSummary <$> use_ GetModSummaryWithoutTimestamps file
-        deps <- use_ GetDependencies file
-        let tdeps = transitiveModuleDeps deps
-            uses_th_qq =
+        deps <- mapMaybe (fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
+        mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps deps
+
+        depSessions <- uses_ GhcSessionDeps deps
+        session' <- liftIO $ mergeEnvs hsc mss $ map hscEnv depSessions
+        let uses_th_qq =
               xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
             dflags = ms_hspp_opts ms
         ifaces <- if uses_th_qq
-                  then uses_ GetModIface tdeps
-                  else uses_ GetModIfaceWithoutLinkable tdeps
-
-        -- Currently GetDependencies returns things in topological order so A comes before B if A imports B.
-        -- We need to reverse this as GHC gets very unhappy otherwise and complains about broken interfaces.
-        -- Long-term we might just want to change the order returned by GetDependencies
-        let inLoadOrder = reverse (map hirHomeMod ifaces)
+                  then uses_ GetModIface deps
+                  else uses_ GetModIfaceWithoutLinkable deps
 
-        session' <- liftIO $ loadModulesHome inLoadOrder <$> setupFinderCache (map hirModSummary ifaces) hsc
-
-        res <- liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
-        return ([], Just res)
+        let session'' = loadModulesHome inLoadOrder $ session'{
+                hsc_HPT = foldMap (hsc_HPT . hscEnv) depSessions
+            }
+            -- Currently GetDependencies returns things in topological order so A comes before B if A imports B.
+            -- We need to reverse this as GHC gets very unhappy otherwise and complains about broken interfaces.
+            -- Long-term we might just want to change the order returned by GetDependencies
+            inLoadOrder = reverse $ map hirHomeMod ifaces
+
+        liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session'' []
+
+-- Merge the HPTs, module graphs and FinderCaches
+mergeEnvs :: HscEnv -> [ModSummary] -> [HscEnv] -> IO HscEnv
+mergeEnvs env mss envs = do
+    prevFinderCache <- concatFC <$> mapM (readIORef . hsc_FC) envs
+    let ims  = map (installedModule (homeUnitId_ $ hsc_dflags env) . moduleName . ms_mod) mss
+        ifrs = zipWith (\ms -> InstalledFound (ms_location ms)) mss ims
+    newFinderCache <- newIORef $
+            foldl'
+                (\fc (im, ifr) -> GHC.extendInstalledModuleEnv fc im ifr) prevFinderCache
+                $ zip ims ifrs
+    return env{
+        hsc_HPT = foldMap hsc_HPT envs,
+        hsc_FC = newFinderCache,
+        hsc_mod_graph = mkModuleGraph $ mss ++ nubOrdOn ms_mod (concatMap (mgModSummaries . hsc_mod_graph) envs)
+    }
+    where
+    -- required because 'FinderCache':
+    --  1) doesn't have a 'Monoid' instance,
+    --  2) is abstract and doesn't export constructors
+    -- To work around this, we coerce to the underlying type
+    -- To remove this, I plan to upstream the missing Monoid instance
+        concatFC :: [FinderCache] -> FinderCache
+        concatFC = unsafeCoerce (mconcat @(Map InstalledModule InstalledFindResult))
 
 -- | Load a iface from disk, or generate it if there isn't one or it is out of date
 -- This rule also ensures that the `.hie` and `.o` (if needed) files are written out.
 getModIfaceFromDiskRule :: Rules ()
 getModIfaceFromDiskRule = defineEarlyCutoff $ Rule $ \GetModIfaceFromDisk f -> do
   ms <- msrModSummary <$> use_ GetModSummary f
-  (diags_session, mb_session) <- ghcSessionDepsDefinition f
+  mb_session <- use GhcSessionDeps f
   case mb_session of
-    Nothing -> return (Nothing, (diags_session, Nothing))
+    Nothing -> return (Nothing, ([], Nothing))
     Just session -> do
       sourceModified <- use_ IsHiFileStable f
       linkableType <- getLinkableType f
       r <- loadInterface (hscEnv session) ms sourceModified linkableType (regenerateHiFile session f ms)
       case r of
-        (diags, Nothing) -> return (Nothing, (diags ++ diags_session, Nothing))
+        (diags, Nothing) -> return (Nothing, (diags, Nothing))
         (diags, Just x) -> do
           let !fp = Just $! hiFileFingerPrint x
-          return (fp, (diags <> diags_session, Just x))
+          return (fp, (diags, Just x))
 
 -- | Check state of hiedb after loading an iface from disk - have we indexed the corresponding `.hie` file?
 -- This function is responsible for ensuring database consistency

From 91e544a0b873af0c1027a025920974d25beb2801 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 10:19:35 +0000
Subject: [PATCH 02/17] format importes

---
 ghcide/src/Development/IDE/Core/Rules.hs | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 35a019aa26..8687307268 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -87,6 +87,8 @@ import           Data.IORef
 import           Data.IntMap.Strict                           (IntMap)
 import qualified Data.IntMap.Strict                           as IntMap
 import           Data.List
+import           Data.List.Extra (nubOrdOn)
+import           Data.Map                                     (Map)
 import qualified Data.Map                                     as M
 import           Data.Maybe
 import qualified Data.Rope.UTF16                              as Rope
@@ -133,13 +135,13 @@ import           Development.IDE.Types.Options
 import           GHC.Generics                                 (Generic)
 import           GHC.IO.Encoding
 import qualified GHC.LanguageExtensions                       as LangExt
+import           GhcPlugins                                   (FinderCache, mgModSummaries)
 import qualified HieDb
 import           Ide.Plugin.Config
 import qualified Language.LSP.Server                          as LSP
 import           Language.LSP.Types                           (SMethod (SCustomMethod))
 import           Language.LSP.VFS
 import           System.Directory                             (canonicalizePath, makeAbsolute)
-
 import           Data.Default                                 (def)
 import           Ide.Plugin.Properties                        (HasProperty,
                                                                KeyNameProxy,
@@ -149,13 +151,7 @@ import           Ide.Plugin.Properties                        (HasProperty,
 import           Ide.PluginUtils                              (configForPlugin)
 import           Ide.Types                                    (DynFlagsModifications (dynFlagsModifyGlobal, dynFlagsModifyParser),
                                                                PluginId)
-import qualified Data.HashSet as HS
-import Unsafe.Coerce (unsafeCoerce)
-import Data.Map (Map)
-import GhcPlugins (FinderCache, mgModSummaries)
-import qualified Development.IDE.GHC.Compat as GHC
-import Development.IDE.GHC.Compat (installedModule)
-import Data.List.Extra (nubOrdOn)
+import           Unsafe.Coerce                                (unsafeCoerce)
 
 -- | This is useful for rules to convert rules that can only produce errors or
 -- a result into the more general IdeResult type that supports producing
@@ -340,7 +336,7 @@ getLocatedImportsRule =
                     return $ if itExists then Just nfp' else Nothing
                 | Just tt <- HM.lookup (TargetModule modName) targets = do
                     -- reuse the existing NormalizedFilePath in order to maximize sharing
-                    let ttmap = HM.mapWithKey const (HS.toMap tt)
+                    let ttmap = HM.mapWithKey const (HashSet.toMap tt)
                         nfp' = HM.lookupDefault nfp nfp ttmap
                     itExists <- getFileExists nfp'
                     return $ if itExists then Just nfp' else Nothing
@@ -730,11 +726,11 @@ ghcSessionDepsDefinition file = do
 mergeEnvs :: HscEnv -> [ModSummary] -> [HscEnv] -> IO HscEnv
 mergeEnvs env mss envs = do
     prevFinderCache <- concatFC <$> mapM (readIORef . hsc_FC) envs
-    let ims  = map (installedModule (homeUnitId_ $ hsc_dflags env) . moduleName . ms_mod) mss
+    let ims  = map (Compat.installedModule (homeUnitId_ $ hsc_dflags env) . moduleName . ms_mod) mss
         ifrs = zipWith (\ms -> InstalledFound (ms_location ms)) mss ims
     newFinderCache <- newIORef $
             foldl'
-                (\fc (im, ifr) -> GHC.extendInstalledModuleEnv fc im ifr) prevFinderCache
+                (\fc (im, ifr) -> Compat.extendInstalledModuleEnv fc im ifr) prevFinderCache
                 $ zip ims ifrs
     return env{
         hsc_HPT = foldMap hsc_HPT envs,

From 1bcf14d8dd8c4cce252f303ecd9c73aa43bd7884 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 10:25:18 +0000
Subject: [PATCH 03/17] clean up

---
 ghcide/.hlint.yaml                         |  2 +-
 ghcide/src/Development/IDE/Core/Compile.hs | 31 +++++++++++++++-
 ghcide/src/Development/IDE/Core/Rules.hs   | 41 +++-------------------
 3 files changed, 36 insertions(+), 38 deletions(-)

diff --git a/ghcide/.hlint.yaml b/ghcide/.hlint.yaml
index 01f035184a..84cd0879a8 100644
--- a/ghcide/.hlint.yaml
+++ b/ghcide/.hlint.yaml
@@ -133,7 +133,7 @@
   # Things that are unsafe in Haskell base library
   - {name: unsafeInterleaveIO, within: [Development.IDE.LSP.LanguageServer]}
   - {name: unsafeDupablePerformIO, within: []}
-  - {name: unsafeCoerce, within: [Ide.Plugin.Eval.Code, Development.IDE.Types.Shake]}
+  - {name: unsafeCoerce, within: [Ide.Plugin.Eval.Code, Development.IDE.Core.Compile, Development.IDE.Types.Shake]}
   # Things that are a bit dangerous in the GHC API
   - {name: nameModule, within: []}
 
diff --git a/ghcide/src/Development/IDE/Core/Compile.hs b/ghcide/src/Development/IDE/Core/Compile.hs
index 13de867963..8c5a8db193 100644
--- a/ghcide/src/Development/IDE/Core/Compile.hs
+++ b/ghcide/src/Development/IDE/Core/Compile.hs
@@ -30,7 +30,7 @@ module Development.IDE.Core.Compile
   , setupFinderCache
   , getDocsBatch
   , lookupName
-  ) where
+  ,mergeEnvs) where
 
 import           Development.IDE.Core.Preprocessor
 import           Development.IDE.Core.RuleTypes
@@ -89,8 +89,10 @@ import           System.Directory
 import           System.FilePath
 import           System.IO.Extra                   (fixIO, newTempFileWithin)
 
+-- GHC API imports
 -- GHC API imports
 import           GHC                               (GetDocsFailure (..),
+                                                    mgModSummaries,
                                                     parsedSource)
 
 import           Control.Concurrent.Extra
@@ -100,11 +102,14 @@ import           Data.Binary
 import           Data.Coerce
 import           Data.Functor
 import qualified Data.HashMap.Strict               as HashMap
+import           Data.Map                          (Map)
 import           Data.Tuple.Extra                  (dupe)
 import           Data.Unique                       as Unique
 import           Development.IDE.Core.Tracing      (withTrace)
+import           GhcPlugins                        (FinderCache)
 import qualified Language.LSP.Server               as LSP
 import qualified Language.LSP.Types                as LSP
+import           Unsafe.Coerce
 
 -- | Given a string buffer, return the string (after preprocessing) and the 'ParsedModule'.
 parseModule
@@ -686,6 +691,30 @@ loadModulesHome mod_infos e =
     where
       mod_name = moduleName . mi_module . hm_iface
 
+-- Merge the HPTs, module graphs and FinderCaches
+mergeEnvs :: HscEnv -> [ModSummary] -> [HomeModInfo] -> [HscEnv] -> IO HscEnv
+mergeEnvs env extraModSummaries extraMods envs = do
+    prevFinderCache <- concatFC <$> mapM (readIORef . hsc_FC) envs
+    let ims  = map (Compat.installedModule (homeUnitId_ $ hsc_dflags env) . moduleName . ms_mod) extraModSummaries
+        ifrs = zipWith (\ms -> InstalledFound (ms_location ms)) extraModSummaries ims
+    newFinderCache <- newIORef $
+            foldl'
+                (\fc (im, ifr) -> Compat.extendInstalledModuleEnv fc im ifr) prevFinderCache
+                $ zip ims ifrs
+    return $ loadModulesHome extraMods $ env{
+        hsc_HPT = foldMap hsc_HPT envs,
+        hsc_FC = newFinderCache,
+        hsc_mod_graph = mkModuleGraph $ extraModSummaries ++ nubOrdOn ms_mod (concatMap (mgModSummaries . hsc_mod_graph) envs)
+    }
+    where
+    -- required because 'FinderCache':
+    --  1) doesn't have a 'Monoid' instance,
+    --  2) is abstract and doesn't export constructors
+    -- To work around this, we coerce to the underlying type
+    -- To remove this, I plan to upstream the missing Monoid instance
+        concatFC :: [FinderCache] -> FinderCache
+        concatFC = unsafeCoerce (mconcat @(Map InstalledModule InstalledFindResult))
+
 withBootSuffix :: HscSource -> ModLocation -> ModLocation
 withBootSuffix HsBootFile = addBootSuffixLocnOut
 withBootSuffix _          = id
diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 8687307268..5ddb8f5ac2 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -87,8 +87,6 @@ import           Data.IORef
 import           Data.IntMap.Strict                           (IntMap)
 import qualified Data.IntMap.Strict                           as IntMap
 import           Data.List
-import           Data.List.Extra (nubOrdOn)
-import           Data.Map                                     (Map)
 import qualified Data.Map                                     as M
 import           Data.Maybe
 import qualified Data.Rope.UTF16                              as Rope
@@ -135,7 +133,6 @@ import           Development.IDE.Types.Options
 import           GHC.Generics                                 (Generic)
 import           GHC.IO.Encoding
 import qualified GHC.LanguageExtensions                       as LangExt
-import           GhcPlugins                                   (FinderCache, mgModSummaries)
 import qualified HieDb
 import           Ide.Plugin.Config
 import qualified Language.LSP.Server                          as LSP
@@ -151,7 +148,6 @@ import           Ide.Plugin.Properties                        (HasProperty,
 import           Ide.PluginUtils                              (configForPlugin)
 import           Ide.Types                                    (DynFlagsModifications (dynFlagsModifyGlobal, dynFlagsModifyParser),
                                                                PluginId)
-import           Unsafe.Coerce                                (unsafeCoerce)
 
 -- | This is useful for rules to convert rules that can only produce errors or
 -- a result into the more general IdeResult type that supports producing
@@ -703,8 +699,7 @@ ghcSessionDepsDefinition file = do
         deps <- mapMaybe (fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
         mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps deps
 
-        depSessions <- uses_ GhcSessionDeps deps
-        session' <- liftIO $ mergeEnvs hsc mss $ map hscEnv depSessions
+        depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
         let uses_th_qq =
               xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
             dflags = ms_hspp_opts ms
@@ -712,39 +707,13 @@ ghcSessionDepsDefinition file = do
                   then uses_ GetModIface deps
                   else uses_ GetModIfaceWithoutLinkable deps
 
-        let session'' = loadModulesHome inLoadOrder $ session'{
-                hsc_HPT = foldMap (hsc_HPT . hscEnv) depSessions
-            }
+        let inLoadOrder = reverse $ map hirHomeMod ifaces
+        session' <- liftIO $ mergeEnvs hsc mss inLoadOrder depSessions
             -- Currently GetDependencies returns things in topological order so A comes before B if A imports B.
             -- We need to reverse this as GHC gets very unhappy otherwise and complains about broken interfaces.
             -- Long-term we might just want to change the order returned by GetDependencies
-            inLoadOrder = reverse $ map hirHomeMod ifaces
-
-        liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session'' []
-
--- Merge the HPTs, module graphs and FinderCaches
-mergeEnvs :: HscEnv -> [ModSummary] -> [HscEnv] -> IO HscEnv
-mergeEnvs env mss envs = do
-    prevFinderCache <- concatFC <$> mapM (readIORef . hsc_FC) envs
-    let ims  = map (Compat.installedModule (homeUnitId_ $ hsc_dflags env) . moduleName . ms_mod) mss
-        ifrs = zipWith (\ms -> InstalledFound (ms_location ms)) mss ims
-    newFinderCache <- newIORef $
-            foldl'
-                (\fc (im, ifr) -> Compat.extendInstalledModuleEnv fc im ifr) prevFinderCache
-                $ zip ims ifrs
-    return env{
-        hsc_HPT = foldMap hsc_HPT envs,
-        hsc_FC = newFinderCache,
-        hsc_mod_graph = mkModuleGraph $ mss ++ nubOrdOn ms_mod (concatMap (mgModSummaries . hsc_mod_graph) envs)
-    }
-    where
-    -- required because 'FinderCache':
-    --  1) doesn't have a 'Monoid' instance,
-    --  2) is abstract and doesn't export constructors
-    -- To work around this, we coerce to the underlying type
-    -- To remove this, I plan to upstream the missing Monoid instance
-        concatFC :: [FinderCache] -> FinderCache
-        concatFC = unsafeCoerce (mconcat @(Map InstalledModule InstalledFindResult))
+
+        liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
 
 -- | Load a iface from disk, or generate it if there isn't one or it is out of date
 -- This rule also ensures that the `.hie` and `.o` (if needed) files are written out.

From 8555d612459d79cba5319dad2a98d34dc94f86eb Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 10:58:57 +0000
Subject: [PATCH 04/17] remove stale comment

---
 ghcide/src/Development/IDE/Core/Rules.hs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 5ddb8f5ac2..ea082eeea1 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -707,11 +707,8 @@ ghcSessionDepsDefinition file = do
                   then uses_ GetModIface deps
                   else uses_ GetModIfaceWithoutLinkable deps
 
-        let inLoadOrder = reverse $ map hirHomeMod ifaces
+        let inLoadOrder = map hirHomeMod ifaces
         session' <- liftIO $ mergeEnvs hsc mss inLoadOrder depSessions
-            -- Currently GetDependencies returns things in topological order so A comes before B if A imports B.
-            -- We need to reverse this as GHC gets very unhappy otherwise and complains about broken interfaces.
-            -- Long-term we might just want to change the order returned by GetDependencies
 
         liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
 

From 680ff1f213e7b722ee12579d8da1bce6c0964e02 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 11:02:03 +0000
Subject: [PATCH 05/17] fix build in GHC 9

---
 ghcide/src/Development/IDE/Core/Compile.hs     | 1 -
 ghcide/src/Development/IDE/GHC/Compat/Units.hs | 2 ++
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Core/Compile.hs b/ghcide/src/Development/IDE/Core/Compile.hs
index 8c5a8db193..de727ca4ad 100644
--- a/ghcide/src/Development/IDE/Core/Compile.hs
+++ b/ghcide/src/Development/IDE/Core/Compile.hs
@@ -106,7 +106,6 @@ import           Data.Map                          (Map)
 import           Data.Tuple.Extra                  (dupe)
 import           Data.Unique                       as Unique
 import           Development.IDE.Core.Tracing      (withTrace)
-import           GhcPlugins                        (FinderCache)
 import qualified Language.LSP.Server               as LSP
 import qualified Language.LSP.Types                as LSP
 import           Unsafe.Coerce
diff --git a/ghcide/src/Development/IDE/GHC/Compat/Units.hs b/ghcide/src/Development/IDE/GHC/Compat/Units.hs
index d36ad94bc8..59583cffd2 100644
--- a/ghcide/src/Development/IDE/GHC/Compat/Units.hs
+++ b/ghcide/src/Development/IDE/GHC/Compat/Units.hs
@@ -45,6 +45,7 @@ module Development.IDE.GHC.Compat.Units (
     ExternalPackageState(..),
     -- * Utils
     filterInplaceUnits,
+    FinderCache,
     ) where
 
 #if MIN_VERSION_ghc(9,0,0)
@@ -59,6 +60,7 @@ import           GHC.Driver.Types
 import           GHC.Data.FastString
 import qualified GHC.Driver.Session              as DynFlags
 import           GHC.Types.Unique.Set
+import           GHC.Unit.Finder                 (finderCache)
 import qualified GHC.Unit.Info                   as UnitInfo
 import           GHC.Unit.State                  (LookupResult, UnitInfo,
                                                   UnitState (unitInfoMap))

From 0019fa9a8e4fc187c59725c6243074223653480f Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 15:11:48 +0000
Subject: [PATCH 06/17] clean up

---
 ghcide/src/Development/IDE/Core/Rules.hs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index ea082eeea1..adc953a674 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -695,9 +695,8 @@ ghcSessionDepsDefinition :: NormalizedFilePath -> Action HscEnvEq
 ghcSessionDepsDefinition file = do
         env <- use_ GhcSession file
         let hsc = hscEnv env
-        ms <- msrModSummary <$> use_ GetModSummaryWithoutTimestamps file
         deps <- mapMaybe (fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
-        mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps deps
+        ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
 
         depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
         let uses_th_qq =

From 1739927003b882aefdd638a8a9cda1545012e639 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 18:33:28 +0000
Subject: [PATCH 07/17] Unify defintions of ghcSessionDeps

---
 ghcide/src/Development/IDE/Core/Rules.hs      | 42 ++++++++++---------
 .../src/Ide/Plugin/Eval/CodeLens.hs           | 26 ++++--------
 2 files changed, 29 insertions(+), 39 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index adc953a674..0ea66f3c23 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -689,27 +689,29 @@ loadGhcSession = do
                 Nothing -> LBS.toStrict $ B.encode (hash (snd val))
         return (Just cutoffHash, val)
 
-    defineNoDiagnostics $ \GhcSessionDeps file -> Just <$> ghcSessionDepsDefinition file
-
-ghcSessionDepsDefinition :: NormalizedFilePath -> Action HscEnvEq
-ghcSessionDepsDefinition file = do
+    defineNoDiagnostics $ \GhcSessionDeps file -> do
         env <- use_ GhcSession file
-        let hsc = hscEnv env
-        deps <- mapMaybe (fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
-        ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
-
-        depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
-        let uses_th_qq =
-              xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
-            dflags = ms_hspp_opts ms
-        ifaces <- if uses_th_qq
-                  then uses_ GetModIface deps
-                  else uses_ GetModIfaceWithoutLinkable deps
-
-        let inLoadOrder = map hirHomeMod ifaces
-        session' <- liftIO $ mergeEnvs hsc mss inLoadOrder depSessions
-
-        liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
+        Just <$> ghcSessionDepsDefinition False env file
+
+ghcSessionDepsDefinition :: Bool -> HscEnvEq -> NormalizedFilePath -> Action HscEnvEq
+ghcSessionDepsDefinition forceLinkable env file = do
+    let hsc = hscEnv env
+    deps <- mapMaybe (fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
+    _ <- uses_ ReportImportCycles deps
+    ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
+
+    depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
+    let uses_th_qq =
+            xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
+        dflags = ms_hspp_opts ms
+    ifaces <- if uses_th_qq || forceLinkable
+                then uses_ GetModIface deps
+                else uses_ GetModIfaceWithoutLinkable deps
+
+    let inLoadOrder = map hirHomeMod ifaces
+    session' <- liftIO $ mergeEnvs hsc mss inLoadOrder depSessions
+
+    liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
 
 -- | Load a iface from disk, or generate it if there isn't one or it is out of date
 -- This rule also ensures that the `.hie` and `.o` (if needed) files are written out.
diff --git a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
index 41dea1bd48..4b2c4a43bd 100644
--- a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
+++ b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
@@ -52,7 +52,7 @@ import           Development.IDE                 (Action, GetDependencies (..),
                                                   HscEnvEq, IdeState,
                                                   ModSummaryResult (..),
                                                   NeedsCompilation (NeedsCompilation),
-                                                  evalGhcEnv,
+                                                  evalGhcEnv, hscEnv,
                                                   hscEnvWithImportPaths,
                                                   prettyPrint, runAction,
                                                   textToStringBuffer,
@@ -61,7 +61,8 @@ import           Development.IDE                 (Action, GetDependencies (..),
                                                   useWithStale_, use_, uses_)
 import           Development.IDE.Core.Compile    (loadModulesHome,
                                                   setupFinderCache)
-import           Development.IDE.Core.Rules      (TransitiveDependencies (transitiveModuleDeps))
+import           Development.IDE.Core.Rules      (TransitiveDependencies (transitiveModuleDeps),
+                                                  ghcSessionDepsDefinition)
 import           Development.IDE.GHC.Compat      hiding (typeKind, unitState)
 import qualified Development.IDE.GHC.Compat      as Compat
 import qualified Development.IDE.GHC.Compat      as SrcLoc
@@ -533,30 +534,17 @@ prettyWarn Warn{..} =
     prettyPrint (SrcLoc.getLoc warnMsg) <> ": warning:\n"
     <> "    " <> SrcLoc.unLoc warnMsg
 
-ghcSessionDepsDefinition :: HscEnvEq -> NormalizedFilePath -> Action HscEnv
-ghcSessionDepsDefinition env file = do
-        let hsc = hscEnvWithImportPaths env
-        deps <- use_ GetDependencies file
-        let tdeps = transitiveModuleDeps deps
-        ifaces <- uses_ GetModIface tdeps
-        liftIO $ assert (all (isJust . hm_linkable . hirHomeMod) ifaces) $ pure ()
-
-        -- Currently GetDependencies returns things in topological order so A comes before B if A imports B.
-        -- We need to reverse this as GHC gets very unhappy otherwise and complains about broken interfaces.
-        -- Long-term we might just want to change the order returned by GetDependencies
-        let inLoadOrder = reverse (map hirHomeMod ifaces)
-
-        liftIO $ loadModulesHome inLoadOrder <$> setupFinderCache (map hirModSummary ifaces) hsc
-
 runGetSession :: MonadIO m => IdeState -> NormalizedFilePath -> m HscEnv
 runGetSession st nfp = liftIO $ runAction "eval" st $ do
     -- Create a new GHC Session rather than reusing an existing one
     -- to avoid interfering with ghcide
+    -- UPDATE: I suspect that this doesn't really work, we always get the same Session
+    --         we probably cache hscEnvs in the Session state
     IdeGhcSession{loadSessionFun} <- useNoFile_ GhcSessionIO
     let fp = fromNormalizedFilePath nfp
     ((_, res),_) <- liftIO $ loadSessionFun fp
-    let hscEnv = fromMaybe (error $ "Unknown file: " <> fp) res
-    ghcSessionDepsDefinition hscEnv nfp
+    let env = fromMaybe (error $ "Unknown file: " <> fp) res
+    hscEnv <$> ghcSessionDepsDefinition False env nfp
 
 needsQuickCheck :: [(Section, Test)] -> Bool
 needsQuickCheck = any (isProperty . snd)

From fdcb77f071cd8ff38f73a2d65a285dbbf0ed83dd Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 18:44:43 +0000
Subject: [PATCH 08/17] mark test as no longer failing

---
 ghcide/test/exe/Main.hs | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 14fa2f6a8a..19b23b8157 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -3843,9 +3843,6 @@ checkFileCompiles fp diag =
 pluginSimpleTests :: TestTree
 pluginSimpleTests =
   ignoreInWindowsForGHC88And810 $
-#if __GLASGOW_HASKELL__ == 810 && __GLASGOW_HASKELL_PATCHLEVEL1__ == 5
-  expectFailBecause "known broken for ghc 8.10.5 (see GHC #19763)" $
-#endif
   testSessionWithExtraFiles "plugin-knownnat" "simple plugin" $ \dir -> do
     _ <- openDoc (dir </> "KnownNat.hs") "haskell"
     liftIO $ writeFile (dir</>"hie.yaml")

From 05f67b6db48b798d939b0605b7f3d8796f0bd60a Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 18:49:58 +0000
Subject: [PATCH 09/17] Prevent duplicate missing module diagnostics

---
 ghcide/src/Development/IDE/Core/Rules.hs      | 40 ++++++++++---------
 .../src/Ide/Plugin/Eval/CodeLens.hs           | 23 ++++-------
 2 files changed, 30 insertions(+), 33 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 0ea66f3c23..fc0c8ae7f8 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -691,27 +691,31 @@ loadGhcSession = do
 
     defineNoDiagnostics $ \GhcSessionDeps file -> do
         env <- use_ GhcSession file
-        Just <$> ghcSessionDepsDefinition False env file
+        ghcSessionDepsDefinition False env file
 
-ghcSessionDepsDefinition :: Bool -> HscEnvEq -> NormalizedFilePath -> Action HscEnvEq
+ghcSessionDepsDefinition :: Bool -> HscEnvEq -> NormalizedFilePath -> Action (Maybe HscEnvEq)
 ghcSessionDepsDefinition forceLinkable env file = do
     let hsc = hscEnv env
-    deps <- mapMaybe (fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
-    _ <- uses_ ReportImportCycles deps
-    ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
-
-    depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
-    let uses_th_qq =
-            xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
-        dflags = ms_hspp_opts ms
-    ifaces <- if uses_th_qq || forceLinkable
-                then uses_ GetModIface deps
-                else uses_ GetModIfaceWithoutLinkable deps
-
-    let inLoadOrder = map hirHomeMod ifaces
-    session' <- liftIO $ mergeEnvs hsc mss inLoadOrder depSessions
-
-    liftIO $ newHscEnvEqWithImportPaths (envImportPaths env) session' []
+
+    mbdeps <- mapM(fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
+    case mbdeps of
+        Nothing -> return Nothing
+        Just deps -> do
+            _ <- uses_ ReportImportCycles deps
+            ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
+
+            depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
+            let uses_th_qq =
+                    xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
+                dflags = ms_hspp_opts ms
+            ifaces <- if uses_th_qq || forceLinkable
+                        then uses_ GetModIface deps
+                        else uses_ GetModIfaceWithoutLinkable deps
+
+            let inLoadOrder = map hirHomeMod ifaces
+            session' <- liftIO $ mergeEnvs hsc mss inLoadOrder depSessions
+
+            Just <$> liftIO (newHscEnvEqWithImportPaths (envImportPaths env) session' [])
 
 -- | Load a iface from disk, or generate it if there isn't one or it is out of date
 -- This rule also ensures that the `.hie` and `.o` (if needed) files are written out.
diff --git a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
index 4b2c4a43bd..db2fa7d230 100644
--- a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
+++ b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
@@ -27,7 +27,7 @@ module Ide.Plugin.Eval.CodeLens (
 
 import           Control.Applicative             (Alternative ((<|>)))
 import           Control.Arrow                   (second, (>>>))
-import           Control.Exception               (assert, try)
+import           Control.Exception               (try)
 import qualified Control.Exception               as E
 import           Control.Lens                    (_1, _3, (%~), (<&>), (^.))
 import           Control.Monad                   (guard, join, void, when)
@@ -38,31 +38,23 @@ import           Data.Char                       (isSpace)
 import qualified Data.HashMap.Strict             as HashMap
 import           Data.List                       (dropWhileEnd, find,
                                                   intercalate, intersperse)
-import           Data.Maybe                      (catMaybes, fromMaybe, isJust)
+import           Data.Maybe                      (catMaybes, fromMaybe)
 import           Data.String                     (IsString)
 import           Data.Text                       (Text)
 import qualified Data.Text                       as T
 import           Data.Time                       (getCurrentTime)
 import           Data.Typeable                   (Typeable)
-import           Development.IDE                 (Action, GetDependencies (..),
-                                                  GetModIface (..),
-                                                  GetModSummary (..),
-                                                  GhcSessionIO (..),
-                                                  HiFileResult (hirHomeMod, hirModSummary),
-                                                  HscEnvEq, IdeState,
+import           Development.IDE                 (GetModSummary (..),
+                                                  GhcSessionIO (..), IdeState,
                                                   ModSummaryResult (..),
                                                   NeedsCompilation (NeedsCompilation),
                                                   evalGhcEnv, hscEnv,
-                                                  hscEnvWithImportPaths,
                                                   prettyPrint, runAction,
                                                   textToStringBuffer,
                                                   toNormalizedFilePath',
                                                   uriToFilePath', useNoFile_,
-                                                  useWithStale_, use_, uses_)
-import           Development.IDE.Core.Compile    (loadModulesHome,
-                                                  setupFinderCache)
-import           Development.IDE.Core.Rules      (TransitiveDependencies (transitiveModuleDeps),
-                                                  ghcSessionDepsDefinition)
+                                                  useWithStale_, use_)
+import           Development.IDE.Core.Rules      (ghcSessionDepsDefinition)
 import           Development.IDE.GHC.Compat      hiding (typeKind, unitState)
 import qualified Development.IDE.GHC.Compat      as Compat
 import qualified Development.IDE.GHC.Compat      as SrcLoc
@@ -544,7 +536,8 @@ runGetSession st nfp = liftIO $ runAction "eval" st $ do
     let fp = fromNormalizedFilePath nfp
     ((_, res),_) <- liftIO $ loadSessionFun fp
     let env = fromMaybe (error $ "Unknown file: " <> fp) res
-    hscEnv <$> ghcSessionDepsDefinition False env nfp
+    res <- fmap hscEnv <$> ghcSessionDepsDefinition False env nfp
+    return $ fromMaybe (error $ "Unable to load file: " <> fp) res
 
 needsQuickCheck :: [(Section, Test)] -> Bool
 needsQuickCheck = any (isProperty . snd)

From fbdda1054822e96baa0a878916f389a0ce0d90d6 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 18:54:52 +0000
Subject: [PATCH 10/17] delete GetDependencies

---
 ghcide/src/Development/IDE/Core/RuleTypes.hs  | 10 +---------
 ghcide/src/Development/IDE/Core/Rules.hs      | 19 +++----------------
 .../IDE/Import/DependencyInformation.hs       |  1 +
 ghcide/src/Development/IDE/Plugin/Test.hs     |  1 -
 ghcide/test/exe/Main.hs                       | 13 +++++--------
 5 files changed, 10 insertions(+), 34 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/RuleTypes.hs b/ghcide/src/Development/IDE/Core/RuleTypes.hs
index 6f8900b54e..5d98fd873b 100644
--- a/ghcide/src/Development/IDE/Core/RuleTypes.hs
+++ b/ghcide/src/Development/IDE/Core/RuleTypes.hs
@@ -73,10 +73,6 @@ type instance RuleResult GetParsedModuleWithComments = ParsedModule
 -- a module could not be parsed or an import cycle.
 type instance RuleResult GetDependencyInformation = DependencyInformation
 
--- | Transitive module and pkg dependencies based on the information produced by GetDependencyInformation.
--- This rule is also responsible for calling ReportImportCycles for each file in the transitive closure.
-type instance RuleResult GetDependencies = TransitiveDependencies
-
 type instance RuleResult GetModuleGraph = DependencyInformation
 
 data GetKnownTargets = GetKnownTargets
@@ -234,6 +230,7 @@ type instance RuleResult GetDocMap = DocAndKindMap
 type instance RuleResult GhcSession = HscEnvEq
 
 -- | A GHC session preloaded with all the dependencies
+-- This rule is also responsible for calling ReportImportCycles for the direct dependencies
 type instance RuleResult GhcSessionDeps = HscEnvEq
 
 -- | Resolve the imports in a module to the file path of a module in the same package
@@ -389,11 +386,6 @@ data ReportImportCycles = ReportImportCycles
 instance Hashable ReportImportCycles
 instance NFData   ReportImportCycles
 
-data GetDependencies = GetDependencies
-    deriving (Eq, Show, Typeable, Generic)
-instance Hashable GetDependencies
-instance NFData   GetDependencies
-
 data TypeCheck = TypeCheck
     deriving (Eq, Show, Typeable, Generic)
 instance Hashable TypeCheck
diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index fc0c8ae7f8..162355d10a 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -11,7 +11,7 @@
 --
 module Development.IDE.Core.Rules(
     -- * Types
-    IdeState, GetDependencies(..), GetParsedModule(..), TransitiveDependencies(..),
+    IdeState, GetParsedModule(..), TransitiveDependencies(..),
     Priority(..), GhcSessionIO(..), GetClientSettings(..),
     -- * Functions
     priorityTypeCheck,
@@ -35,7 +35,6 @@ module Development.IDE.Core.Rules(
     getLocatedImportsRule,
     getDependencyInformationRule,
     reportImportCyclesRule,
-    getDependenciesRule,
     typeCheckRule,
     getDocMapRule,
     loadGhcSession,
@@ -161,7 +160,8 @@ toIdeResult = either (, Nothing) (([],) . Just)
 -- | Get all transitive file dependencies of a given module.
 -- Does not include the file itself.
 getDependencies :: NormalizedFilePath -> Action (Maybe [NormalizedFilePath])
-getDependencies file = fmap transitiveModuleDeps <$> use GetDependencies file
+getDependencies file =
+    fmap transitiveModuleDeps . (`transitiveDeps` file) <$> use_ GetDependencyInformation file
 
 getSourceFileSource :: NormalizedFilePath -> Action BS.ByteString
 getSourceFileSource nfp = do
@@ -490,18 +490,6 @@ reportImportCyclesRule =
            pure (moduleNameString . moduleName . ms_mod $ ms)
           showCycle mods  = T.intercalate ", " (map T.pack mods)
 
--- returns all transitive dependencies in topological order.
--- NOTE: result does not include the argument file.
-getDependenciesRule :: Rules ()
-getDependenciesRule =
-    defineEarlyCutoff $ RuleNoDiagnostics $ \GetDependencies file -> do
-        depInfo <- use_ GetDependencyInformation file
-        let allFiles = reachableModules depInfo
-        _ <- uses_ ReportImportCycles allFiles
-        opts <- getIdeOptions
-        let mbFingerprints = map (Util.fingerprintString . fromNormalizedFilePath) allFiles <$ optShakeFiles opts
-        return (fingerprintToBS . Util.fingerprintFingerprints <$> mbFingerprints, transitiveDeps depInfo file)
-
 getHieAstsRule :: Rules ()
 getHieAstsRule =
     define $ \GetHieAst f -> do
@@ -1065,7 +1053,6 @@ mainRule = do
     getLocatedImportsRule
     getDependencyInformationRule
     reportImportCyclesRule
-    getDependenciesRule
     typeCheckRule
     getDocMapRule
     loadGhcSession
diff --git a/ghcide/src/Development/IDE/Import/DependencyInformation.hs b/ghcide/src/Development/IDE/Import/DependencyInformation.hs
index 9e58cbd0f6..6f85af7678 100644
--- a/ghcide/src/Development/IDE/Import/DependencyInformation.hs
+++ b/ghcide/src/Development/IDE/Import/DependencyInformation.hs
@@ -327,6 +327,7 @@ immediateReverseDependencies file DependencyInformation{..} = do
   FilePathId cur_id <- lookupPathToId depPathIdMap file
   return $ map (idToPath depPathIdMap . FilePathId) (maybe mempty IntSet.toList (IntMap.lookup cur_id depReverseModuleDeps))
 
+-- | returns all transitive dependencies in topological order.
 transitiveDeps :: DependencyInformation -> NormalizedFilePath -> Maybe TransitiveDependencies
 transitiveDeps DependencyInformation{..} file = do
   let !fileId = pathToId depPathIdMap file
diff --git a/ghcide/src/Development/IDE/Plugin/Test.hs b/ghcide/src/Development/IDE/Plugin/Test.hs
index 881aed4406..14e861f38b 100644
--- a/ghcide/src/Development/IDE/Plugin/Test.hs
+++ b/ghcide/src/Development/IDE/Plugin/Test.hs
@@ -150,7 +150,6 @@ parseAction "getparsedmodule" fp = Right . isJust <$> use GetParsedModule fp
 parseAction "ghcsession" fp = Right . isJust <$> use GhcSession fp
 parseAction "ghcsessiondeps" fp = Right . isJust <$> use GhcSessionDeps fp
 parseAction "gethieast" fp = Right . isJust <$> use GetHieAst fp
-parseAction "getDependencies" fp = Right . isJust <$> use GetDependencies fp
 parseAction "getFileContents" fp = Right . isJust <$> use GetFileContents fp
 parseAction other _ = return $ Left $ "Cannot parse ide rule: " <> pack (original other)
 
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 19b23b8157..5ae5709e94 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -669,9 +669,9 @@ diagnosticTests = testGroup "diagnostics"
       expectDiagnostics [("Foo.hs", [(DsError, (1,7), "Could not find module 'MissingModule'")])]
 
   , testGroup "Cancellation"
-    [ cancellationTestGroup "edit header" editHeader yesDepends yesSession noParse  noTc
-    , cancellationTestGroup "edit import" editImport noDepends  noSession  yesParse noTc
-    , cancellationTestGroup "edit body"   editBody   yesDepends yesSession yesParse yesTc
+    [ cancellationTestGroup "edit header" editHeader yesSession noParse  noTc
+    , cancellationTestGroup "edit import" editImport noSession  yesParse noTc
+    , cancellationTestGroup "edit body"   editBody   yesSession yesParse yesTc
     ]
   ]
   where
@@ -685,17 +685,14 @@ diagnosticTests = testGroup "diagnostics"
       noParse = False
       yesParse = True
 
-      noDepends = False
-      yesDepends = True
-
       noSession = False
       yesSession = True
 
       noTc = False
       yesTc = True
 
-cancellationTestGroup :: TestName -> (TextDocumentContentChangeEvent, TextDocumentContentChangeEvent) -> Bool -> Bool -> Bool -> Bool -> TestTree
-cancellationTestGroup name edits dependsOutcome sessionDepsOutcome parseOutcome tcOutcome = testGroup name
+cancellationTestGroup :: TestName -> (TextDocumentContentChangeEvent, TextDocumentContentChangeEvent) -> Bool -> Bool -> Bool -> TestTree
+cancellationTestGroup name edits sessionDepsOutcome parseOutcome tcOutcome = testGroup name
     [ cancellationTemplate edits Nothing
     , cancellationTemplate edits $ Just ("GetFileContents", True)
     , cancellationTemplate edits $ Just ("GhcSession", True)

From 1bf410f7a3d2a21da03d2dc93e80649cfb96934a Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 19:21:46 +0000
Subject: [PATCH 11/17] add a test for deeply nested import cycles

---
 ghcide/test/exe/Main.hs | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 5ae5709e94..39ecd961dd 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -410,6 +410,30 @@ diagnosticTests = testGroup "diagnostics"
           , [(DsError, (1, 7), "Cyclic module dependency between ModuleA, ModuleB")]
           )
         ]
+  , testSession' "deeply nested cyclic module dependency" $ \path -> do
+      let contentA = unlines
+            [ "module ModuleA where" , "import ModuleB" ]
+      let contentB = unlines
+            [ "module ModuleB where" , "import ModuleA" ]
+      let contentC = unlines
+            [ "module ModuleC where" , "import ModuleB" ]
+      let contentD = T.unlines
+            [ "module ModuleD where" , "import ModuleC" ]
+          cradle =
+            "cradle: {direct: {arguments: [ModuleA, ModuleB, ModuleC, ModuleD]}}"
+      liftIO $ writeFile (path </> "ModuleA.hs") contentA
+      liftIO $ writeFile (path </> "ModuleB.hs") contentB
+      liftIO $ writeFile (path </> "ModuleC.hs") contentC
+      liftIO $ writeFile (path </> "hie.yaml") cradle
+      _ <- createDoc "ModuleD.hs" "haskell" contentD
+      expectDiagnostics
+        [ ( "ModuleA.hs"
+          , [(DsError, (1, 7), "Cyclic module dependency between ModuleA, ModuleB")]
+          )
+        , ( "ModuleB.hs"
+          , [(DsError, (1, 7), "Cyclic module dependency between ModuleA, ModuleB")]
+          )
+        ]
   , testSessionWait "cyclic module dependency with hs-boot" $ do
       let contentA = T.unlines
             [ "module ModuleA where"

From f2137c990f775eab3013c97aaab1077a9362a6f2 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 20:12:04 +0000
Subject: [PATCH 12/17] Fix build in GHC 9.0

---
 ghcide/src/Development/IDE/GHC/Compat/Units.hs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/GHC/Compat/Units.hs b/ghcide/src/Development/IDE/GHC/Compat/Units.hs
index 59583cffd2..61f8d82644 100644
--- a/ghcide/src/Development/IDE/GHC/Compat/Units.hs
+++ b/ghcide/src/Development/IDE/GHC/Compat/Units.hs
@@ -54,13 +54,13 @@ import qualified GHC.Data.ShortText              as ST
 import           GHC.Driver.Env                  (hsc_unit_dbs)
 import           GHC.Unit.Env
 import           GHC.Unit.External
+import           GHC.Unit.Finder
 #else
 import           GHC.Driver.Types
 #endif
 import           GHC.Data.FastString
 import qualified GHC.Driver.Session              as DynFlags
 import           GHC.Types.Unique.Set
-import           GHC.Unit.Finder                 (finderCache)
 import qualified GHC.Unit.Info                   as UnitInfo
 import           GHC.Unit.State                  (LookupResult, UnitInfo,
                                                   UnitState (unitInfoMap))

From 3e03be5c8fb7062531b6edfa35a8fccc4ce576dc Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Tue, 2 Nov 2021 20:54:13 +0000
Subject: [PATCH 13/17] bump ghcide version

---
 ghcide/ghcide.cabal                           | 2 +-
 plugins/hls-eval-plugin/hls-eval-plugin.cabal | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/ghcide/ghcide.cabal b/ghcide/ghcide.cabal
index a6da170c14..aa5a0e1b9f 100644
--- a/ghcide/ghcide.cabal
+++ b/ghcide/ghcide.cabal
@@ -2,7 +2,7 @@ cabal-version:      2.4
 build-type:         Simple
 category:           Development
 name:               ghcide
-version:            1.4.2.3
+version:            1.4.2.4
 license:            Apache-2.0
 license-file:       LICENSE
 author:             Digital Asset and Ghcide contributors
diff --git a/plugins/hls-eval-plugin/hls-eval-plugin.cabal b/plugins/hls-eval-plugin/hls-eval-plugin.cabal
index e37acde140..d6f0f508fe 100644
--- a/plugins/hls-eval-plugin/hls-eval-plugin.cabal
+++ b/plugins/hls-eval-plugin/hls-eval-plugin.cabal
@@ -64,7 +64,7 @@ library
     , ghc
     , ghc-boot-th
     , ghc-paths
-    , ghcide                >=1.2   && <1.5
+    , ghcide                >=1.4.2.4 && <1.5
     , hashable
     , hls-graph
     , hls-plugin-api        ^>=1.2

From 9f95dbb26023cc9d9d3ee97927838eeb9bc06254 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Fri, 5 Nov 2021 19:04:27 +0000
Subject: [PATCH 14/17] Introduce config options for the main rules

Surfacing the performance tradeoffs in the core build rules
---
 ghcide/exe/Main.hs                            |  3 +-
 ghcide/src/Development/IDE/Core/Rules.hs      | 51 ++++++++++++++-----
 ghcide/src/Development/IDE/Main.hs            |  2 +-
 ghcide/test/exe/Main.hs                       |  1 -
 plugins/hls-eval-plugin/hls-eval-plugin.cabal |  1 +
 .../src/Ide/Plugin/Eval/CodeLens.hs           |  7 ++-
 6 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/ghcide/exe/Main.hs b/ghcide/exe/Main.hs
index 78af32e8ba..1e4f367140 100644
--- a/ghcide/exe/Main.hs
+++ b/ghcide/exe/Main.hs
@@ -8,6 +8,7 @@ module Main(main) where
 import           Arguments                         (Arguments (..),
                                                     getArguments)
 import           Control.Monad.Extra               (unless, whenJust)
+import           Data.Default                      (def)
 import           Data.Version                      (showVersion)
 import           Development.GitRev                (gitHash)
 import           Development.IDE                   (Priority (Debug, Info),
@@ -60,7 +61,7 @@ main = withTelemetryLogger $ \telemetryLogger -> do
 
         ,Main.argsRules = do
             -- install the main and ghcide-plugin rules
-            mainRule
+            mainRule def
             -- install the kick action, which triggers a typecheck on every
             -- Shake database restart, i.e. on every user edit.
             unless argsDisableKick $
diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 162355d10a..4ea001a432 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -22,6 +22,7 @@ module Development.IDE.Core.Rules(
     defineNoFile,
     defineEarlyCutOffNoFile,
     mainRule,
+    RulesConfig(..),
     getDependencies,
     getParsedModule,
     getParsedModuleWithComments,
@@ -56,6 +57,7 @@ module Development.IDE.Core.Rules(
     ghcSessionDepsDefinition,
     getParsedModuleDefinition,
     typeCheckRuleDefinition,
+    GhcSessionDepsConfig(..),
     ) where
 
 #if !MIN_VERSION_ghc(8,8,0)
@@ -138,7 +140,7 @@ import qualified Language.LSP.Server                          as LSP
 import           Language.LSP.Types                           (SMethod (SCustomMethod))
 import           Language.LSP.VFS
 import           System.Directory                             (canonicalizePath, makeAbsolute)
-import           Data.Default                                 (def)
+import           Data.Default                                 (def, Default)
 import           Ide.Plugin.Properties                        (HasProperty,
                                                                KeyNameProxy,
                                                                Properties,
@@ -640,8 +642,8 @@ currentLinkables = do
   where
     go (mod, time) = LM time mod []
 
-loadGhcSession :: Rules ()
-loadGhcSession = do
+loadGhcSession :: GhcSessionDepsConfig -> Rules ()
+loadGhcSession ghcSessionDepsConfig = do
     -- This function should always be rerun because it tracks changes
     -- to the version of the collection of HscEnv's.
     defineEarlyCutOffNoFile $ \GhcSessionIO -> do
@@ -679,24 +681,34 @@ loadGhcSession = do
 
     defineNoDiagnostics $ \GhcSessionDeps file -> do
         env <- use_ GhcSession file
-        ghcSessionDepsDefinition False env file
-
-ghcSessionDepsDefinition :: Bool -> HscEnvEq -> NormalizedFilePath -> Action (Maybe HscEnvEq)
-ghcSessionDepsDefinition forceLinkable env file = do
+        ghcSessionDepsDefinition ghcSessionDepsConfig env file
+
+data GhcSessionDepsConfig = GhcSessionDepsConfig
+    { checkForImportCycles :: Bool
+    , forceLinkables       :: Bool
+    }
+instance Default GhcSessionDepsConfig where
+  def = GhcSessionDepsConfig
+    { checkForImportCycles = True
+    , forceLinkables = False
+    }
+
+ghcSessionDepsDefinition :: GhcSessionDepsConfig -> HscEnvEq -> NormalizedFilePath -> Action (Maybe HscEnvEq)
+ghcSessionDepsDefinition GhcSessionDepsConfig{..} env file = do
     let hsc = hscEnv env
 
     mbdeps <- mapM(fmap artifactFilePath . snd) <$> use_ GetLocatedImports file
     case mbdeps of
         Nothing -> return Nothing
         Just deps -> do
-            _ <- uses_ ReportImportCycles deps
+            when checkForImportCycles $ void $ uses_ ReportImportCycles deps
             ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
 
             depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
             let uses_th_qq =
                     xopt LangExt.TemplateHaskell dflags || xopt LangExt.QuasiQuotes dflags
                 dflags = ms_hspp_opts ms
-            ifaces <- if uses_th_qq || forceLinkable
+            ifaces <- if uses_th_qq || forceLinkables
                         then uses_ GetModIface deps
                         else uses_ GetModIfaceWithoutLinkable deps
 
@@ -1043,9 +1055,18 @@ writeHiFileAction hsc hiFile = do
         resetInterfaceStore extras $ toNormalizedFilePath' targetPath
         writeHiFile hsc hiFile
 
+data RulesConfig = RulesConfig
+    { -- | Disable import cycle checking for improved performance in large codebases
+      checkForImportCycles :: Bool
+    -- | Disable TH for improved performance in large codebases
+    , enableTemplateHaskell :: Bool
+    }
+
+instance Default RulesConfig where def = RulesConfig True True
+
 -- | A rule that wires per-file rules together
-mainRule :: Rules ()
-mainRule = do
+mainRule :: RulesConfig -> Rules ()
+mainRule RulesConfig{..} = do
     linkables <- liftIO $ newVar emptyModuleEnv
     addIdeGlobal $ CompiledLinkables linkables
     getParsedModuleRule
@@ -1055,7 +1076,7 @@ mainRule = do
     reportImportCyclesRule
     typeCheckRule
     getDocMapRule
-    loadGhcSession
+    loadGhcSession def{checkForImportCycles}
     getModIfaceFromDiskRule
     getModIfaceFromDiskAndIndexRule
     getModIfaceRule
@@ -1073,8 +1094,10 @@ mainRule = do
     --   * ObjectLinkable -> BCOLinkable : the prev linkable can be reused,  signal "no change"
     --   * Object/BCO -> NoLinkable      : the prev linkable can be ignored, signal "no change"
     --   * otherwise                     : the prev linkable cannot be reused, signal "value has changed"
-    defineEarlyCutoff $ RuleWithCustomNewnessCheck (<=) $ \NeedsCompilation file ->
-        needsCompilationRule file
+    if enableTemplateHaskell
+      then defineEarlyCutoff $ RuleWithCustomNewnessCheck (<=) $ \NeedsCompilation file ->
+                needsCompilationRule file
+      else defineNoDiagnostics $ \NeedsCompilation _ -> return $ Just Nothing
     generateCoreRule
     getImportMapRule
     getAnnotatedParsedSourceRule
diff --git a/ghcide/src/Development/IDE/Main.hs b/ghcide/src/Development/IDE/Main.hs
index a732fcd6fb..f35c45d526 100644
--- a/ghcide/src/Development/IDE/Main.hs
+++ b/ghcide/src/Development/IDE/Main.hs
@@ -187,7 +187,7 @@ defaultArguments priority = Arguments
         { argsOTMemoryProfiling = False
         , argCommand = LSP
         , argsLogger = stderrLogger priority
-        , argsRules = mainRule >> action kick
+        , argsRules = mainRule def >> action kick
         , argsGhcidePlugin = mempty
         , argsHlsPlugins = pluginDescToIdePlugins Ghcide.descriptors
         , argsSessionLoadingOptions = def
diff --git a/ghcide/test/exe/Main.hs b/ghcide/test/exe/Main.hs
index 39ecd961dd..d021feea49 100644
--- a/ghcide/test/exe/Main.hs
+++ b/ghcide/test/exe/Main.hs
@@ -725,7 +725,6 @@ cancellationTestGroup name edits sessionDepsOutcome parseOutcome tcOutcome = tes
     , cancellationTemplate edits $ Just ("GetModSummaryWithoutTimestamps", True)
       -- getLocatedImports never fails
     , cancellationTemplate edits $ Just ("GetLocatedImports", True)
-    , cancellationTemplate edits $ Just ("GetDependencies", dependsOutcome)
     , cancellationTemplate edits $ Just ("GhcSessionDeps", sessionDepsOutcome)
     , cancellationTemplate edits $ Just ("GetParsedModule", parseOutcome)
     , cancellationTemplate edits $ Just ("TypeCheck", tcOutcome)
diff --git a/plugins/hls-eval-plugin/hls-eval-plugin.cabal b/plugins/hls-eval-plugin/hls-eval-plugin.cabal
index d6f0f508fe..e3114e1656 100644
--- a/plugins/hls-eval-plugin/hls-eval-plugin.cabal
+++ b/plugins/hls-eval-plugin/hls-eval-plugin.cabal
@@ -55,6 +55,7 @@ library
     , aeson
     , base                  >=4.12  && <5
     , containers
+    , data-default
     , deepseq
     , Diff                  ^>=0.4.0
     , directory
diff --git a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
index db2fa7d230..46ab009470 100644
--- a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
+++ b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
@@ -35,6 +35,7 @@ import           Control.Monad.IO.Class          (MonadIO (liftIO))
 import           Control.Monad.Trans.Except      (ExceptT (..))
 import           Data.Aeson                      (toJSON)
 import           Data.Char                       (isSpace)
+import           Data.Default
 import qualified Data.HashMap.Strict             as HashMap
 import           Data.List                       (dropWhileEnd, find,
                                                   intercalate, intersperse)
@@ -54,7 +55,8 @@ import           Development.IDE                 (GetModSummary (..),
                                                   toNormalizedFilePath',
                                                   uriToFilePath', useNoFile_,
                                                   useWithStale_, use_)
-import           Development.IDE.Core.Rules      (ghcSessionDepsDefinition)
+import           Development.IDE.Core.Rules      (GhcSessionDepsConfig (..),
+                                                  ghcSessionDepsDefinition)
 import           Development.IDE.GHC.Compat      hiding (typeKind, unitState)
 import qualified Development.IDE.GHC.Compat      as Compat
 import qualified Development.IDE.GHC.Compat      as SrcLoc
@@ -536,7 +538,8 @@ runGetSession st nfp = liftIO $ runAction "eval" st $ do
     let fp = fromNormalizedFilePath nfp
     ((_, res),_) <- liftIO $ loadSessionFun fp
     let env = fromMaybe (error $ "Unknown file: " <> fp) res
-    res <- fmap hscEnv <$> ghcSessionDepsDefinition False env nfp
+        ghcSessionDepsConfig = def{forceLinkables = True, checkForImportCycles = False}
+    res <- fmap hscEnv <$> ghcSessionDepsDefinition ghcSessionDepsConfig env nfp
     return $ fromMaybe (error $ "Unable to load file: " <> fp) res
 
 needsQuickCheck :: [(Section, Test)] -> Bool

From bf2dbfadf4fbd8dba96b76c08960d17389fe848a Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 6 Nov 2021 08:10:21 +0000
Subject: [PATCH 15/17] Avoid using the Monoid instance (removed in 9.4 ?????)

---
 ghcide/src/Development/IDE/Core/Compile.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Core/Compile.hs b/ghcide/src/Development/IDE/Core/Compile.hs
index de727ca4ad..bf027aacbb 100644
--- a/ghcide/src/Development/IDE/Core/Compile.hs
+++ b/ghcide/src/Development/IDE/Core/Compile.hs
@@ -108,6 +108,7 @@ import           Data.Unique                       as Unique
 import           Development.IDE.Core.Tracing      (withTrace)
 import qualified Language.LSP.Server               as LSP
 import qualified Language.LSP.Types                as LSP
+import           UniqDFM                           (emptyUDFM, plusUDFM)
 import           Unsafe.Coerce
 
 -- | Given a string buffer, return the string (after preprocessing) and the 'ParsedModule'.
@@ -701,7 +702,7 @@ mergeEnvs env extraModSummaries extraMods envs = do
                 (\fc (im, ifr) -> Compat.extendInstalledModuleEnv fc im ifr) prevFinderCache
                 $ zip ims ifrs
     return $ loadModulesHome extraMods $ env{
-        hsc_HPT = foldMap hsc_HPT envs,
+        hsc_HPT = foldMapBy plusUDFM emptyUDFM hsc_HPT envs,
         hsc_FC = newFinderCache,
         hsc_mod_graph = mkModuleGraph $ extraModSummaries ++ nubOrdOn ms_mod (concatMap (mgModSummaries . hsc_mod_graph) envs)
     }

From 9d6ba9e6536bd0090529ee015ec37c97efc9dfac Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 6 Nov 2021 08:22:58 +0000
Subject: [PATCH 16/17] Fix build with GHC 9

---
 ghcide/src/Development/IDE/Core/Compile.hs    | 2 +-
 ghcide/src/Development/IDE/GHC/Compat/Util.hs | 5 +++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/ghcide/src/Development/IDE/Core/Compile.hs b/ghcide/src/Development/IDE/Core/Compile.hs
index bf027aacbb..75d5870e24 100644
--- a/ghcide/src/Development/IDE/Core/Compile.hs
+++ b/ghcide/src/Development/IDE/Core/Compile.hs
@@ -106,9 +106,9 @@ import           Data.Map                          (Map)
 import           Data.Tuple.Extra                  (dupe)
 import           Data.Unique                       as Unique
 import           Development.IDE.Core.Tracing      (withTrace)
+import           Development.IDE.GHC.Compat.Util   (emptyUDFM, plusUDFM)
 import qualified Language.LSP.Server               as LSP
 import qualified Language.LSP.Types                as LSP
-import           UniqDFM                           (emptyUDFM, plusUDFM)
 import           Unsafe.Coerce
 
 -- | Given a string buffer, return the string (after preprocessing) and the 'ParsedModule'.
diff --git a/ghcide/src/Development/IDE/GHC/Compat/Util.hs b/ghcide/src/Development/IDE/GHC/Compat/Util.hs
index 198a94c03b..0b1ff0f6c0 100644
--- a/ghcide/src/Development/IDE/GHC/Compat/Util.hs
+++ b/ghcide/src/Development/IDE/GHC/Compat/Util.hs
@@ -59,6 +59,9 @@ module Development.IDE.GHC.Compat.Util (
     Unique,
     mkUnique,
     newTagUnique,
+    -- * UniqDFM
+    emptyUDFM,
+    plusUDFM,
     -- * String Buffer
     StringBuffer(..),
     hGetStringBuffer,
@@ -76,6 +79,7 @@ import           GHC.Data.Maybe
 import           GHC.Data.Pair
 import           GHC.Data.StringBuffer
 import           GHC.Types.Unique
+import           GHC.Types.Unique.DFM
 import           GHC.Utils.Fingerprint
 import           GHC.Utils.Misc
 import           GHC.Utils.Outputable    (pprHsString)
@@ -94,6 +98,7 @@ import           Pair
 import           Outputable              (pprHsString)
 import           Panic                   hiding (try)
 import           StringBuffer
+import           UniqDFM
 import           Unique
 import           Util
 #endif

From ef370d52de08f229a2f956bcde5127fe17a77ce8 Mon Sep 17 00:00:00 2001
From: Pepe Iborra <pepeiborra@gmail.com>
Date: Sat, 6 Nov 2021 15:22:04 +0000
Subject: [PATCH 17/17] Fix Eval plugin

---
 ghcide/src/Development/IDE/Core/Rules.hs                | 6 +++++-
 plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs | 9 +++++++--
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/ghcide/src/Development/IDE/Core/Rules.hs b/ghcide/src/Development/IDE/Core/Rules.hs
index 4ea001a432..1dc0c0f2a2 100644
--- a/ghcide/src/Development/IDE/Core/Rules.hs
+++ b/ghcide/src/Development/IDE/Core/Rules.hs
@@ -686,11 +686,13 @@ loadGhcSession ghcSessionDepsConfig = do
 data GhcSessionDepsConfig = GhcSessionDepsConfig
     { checkForImportCycles :: Bool
     , forceLinkables       :: Bool
+    , fullModSummary       :: Bool
     }
 instance Default GhcSessionDepsConfig where
   def = GhcSessionDepsConfig
     { checkForImportCycles = True
     , forceLinkables = False
+    , fullModSummary = False
     }
 
 ghcSessionDepsDefinition :: GhcSessionDepsConfig -> HscEnvEq -> NormalizedFilePath -> Action (Maybe HscEnvEq)
@@ -702,7 +704,9 @@ ghcSessionDepsDefinition GhcSessionDepsConfig{..} env file = do
         Nothing -> return Nothing
         Just deps -> do
             when checkForImportCycles $ void $ uses_ ReportImportCycles deps
-            ms:mss <- map msrModSummary <$> uses_ GetModSummaryWithoutTimestamps (file:deps)
+            ms:mss <- map msrModSummary <$> if fullModSummary
+                then uses_ GetModSummary (file:deps)
+                else uses_ GetModSummaryWithoutTimestamps (file:deps)
 
             depSessions <- map hscEnv <$> uses_ GhcSessionDeps deps
             let uses_th_qq =
diff --git a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
index 46ab009470..ef9541eba0 100644
--- a/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
+++ b/plugins/hls-eval-plugin/src/Ide/Plugin/Eval/CodeLens.hs
@@ -50,6 +50,7 @@ import           Development.IDE                 (GetModSummary (..),
                                                   ModSummaryResult (..),
                                                   NeedsCompilation (NeedsCompilation),
                                                   evalGhcEnv, hscEnv,
+                                                  hscEnvWithImportPaths,
                                                   prettyPrint, runAction,
                                                   textToStringBuffer,
                                                   toNormalizedFilePath',
@@ -538,8 +539,12 @@ runGetSession st nfp = liftIO $ runAction "eval" st $ do
     let fp = fromNormalizedFilePath nfp
     ((_, res),_) <- liftIO $ loadSessionFun fp
     let env = fromMaybe (error $ "Unknown file: " <> fp) res
-        ghcSessionDepsConfig = def{forceLinkables = True, checkForImportCycles = False}
-    res <- fmap hscEnv <$> ghcSessionDepsDefinition ghcSessionDepsConfig env nfp
+        ghcSessionDepsConfig = def
+            { forceLinkables = True
+            , checkForImportCycles = False
+            , fullModSummary = True
+            }
+    res <- fmap hscEnvWithImportPaths <$> ghcSessionDepsDefinition ghcSessionDepsConfig env nfp
     return $ fromMaybe (error $ "Unable to load file: " <> fp) res
 
 needsQuickCheck :: [(Section, Test)] -> Bool