Don't return complete HscEnv from upsweepwip/23305

By returning a complete HscEnv from upsweep the logger (as introduced by
withDeferredDiagnostics) was escaping the scope of
withDeferredDiagnostics and hence we were losing error messages.

This is reminiscent of #20981, which also talks about writing errors
into messages after their scope has ended.

See #23305 for details.

2 files changed, 8 insertions, 6 deletions

diff --git a/compiler/GHC/Driver/Make.hs b/compiler/GHC/Driver/Make.hs
index 7a42440e16..c9efc87f03 100644
--- a/compiler/GHC/Driver/Make.hs
+++ b/compiler/GHC/Driver/Make.hs
@@ -772,10 +772,10 @@ load' mhmi_cache how_much mHscMessage mod_graph = do
     worker_limit <- liftIO $ mkWorkerLimit dflags
 
     setSession $ hscUpdateHUG (unitEnv_map pruneHomeUnitEnv) hsc_env
-    (upsweep_ok, hsc_env1) <- withDeferredDiagnostics $ do
+    (upsweep_ok, new_deps) <- withDeferredDiagnostics $ do
       hsc_env <- getSession
       liftIO $ upsweep worker_limit hsc_env mhmi_cache mHscMessage (toCache pruned_cache) build_plan
-    setSession hsc_env1
+    modifySession (addDepsToHscEnv new_deps)
     case upsweep_ok of
       Failed -> loadFinish upsweep_ok
       Succeeded -> do
@@ -1248,14 +1248,13 @@ upsweep
     -> Maybe Messager
     -> M.Map ModNodeKeyWithUid HomeModInfo
     -> [BuildPlan]
-    -> IO (SuccessFlag, HscEnv)
+    -> IO (SuccessFlag, [HomeModInfo])
 upsweep n_jobs hsc_env hmi_cache mHscMessage old_hpt build_plan = do
     (cycle, pipelines, collect_result) <- interpretBuildPlan (hsc_HUG hsc_env) hmi_cache old_hpt build_plan
     runPipelines n_jobs hsc_env mHscMessage pipelines
     res <- collect_result
 
     let completed = [m | Just (Just m) <- res]
-    let hsc_env' = addDepsToHscEnv completed hsc_env
 
     -- Handle any cycle in the original compilation graph and return the result
     -- of the upsweep.
@@ -1263,10 +1262,10 @@ upsweep n_jobs hsc_env hmi_cache mHscMessage old_hpt build_plan = do
         Just mss -> do
           let logger = hsc_logger hsc_env
           liftIO $ fatalErrorMsg logger (cyclicModuleErr mss)
-          return (Failed, hsc_env)
+          return (Failed, [])
         Nothing  -> do
           let success_flag = successIf (all isJust res)
-          return (success_flag, hsc_env')
+          return (success_flag, completed)
 
 toCache :: [HomeModInfo] -> M.Map (ModNodeKeyWithUid) HomeModInfo
 toCache hmis = M.fromList ([(miKey $ hm_iface hmi, hmi) | hmi <- hmis])
diff --git a/testsuite/tests/ghci/prog018/prog018.stdout b/testsuite/tests/ghci/prog018/prog018.stdout
index 1fff03d755..19a2049c2b 100644
--- a/testsuite/tests/ghci/prog018/prog018.stdout
+++ b/testsuite/tests/ghci/prog018/prog018.stdout
@@ -19,4 +19,7 @@ C.hs:6:7: error: [GHC-88464]
     Variable not in scope: variableNotInScope :: ()
 Failed, two modules loaded.
 [3 of 3] Compiling C                ( C.hs, interpreted )
+
+C.hs:6:7: error: [GHC-88464]
+    Variable not in scope: variableNotInScope :: ()
 Failed, two modules loaded.