From 16ba75714cc22aeb86425679ad24b996a2b30fea Mon Sep 17 00:00:00 2001
From: Simon Marlow <marlowsd@gmail.com>
Date: Fri, 7 Dec 2012 12:05:29 +0000
Subject: [PATCH] Invalidate the ModSummary cache in setSessionDynFlags (#7478)
---
compiler/main/GHC.hs | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index b1cc7868400b..82d5a8ad6e75 100644
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -498,6 +498,7 @@ setSessionDynFlags dflags = do
(dflags', preload) <- liftIO $ initPackages dflags
modifySession $ \h -> h{ hsc_dflags = dflags'
, hsc_IC = (hsc_IC h){ ic_dflags = dflags' } }
+ invalidateModSummaryCache
return preload
-- | Sets the program 'DynFlags'.
@@ -505,8 +506,34 @@ setProgramDynFlags :: GhcMonad m => DynFlags -> m [PackageId]
setProgramDynFlags dflags = do
(dflags', preload) <- liftIO $ initPackages dflags
modifySession $ \h -> h{ hsc_dflags = dflags' }
+ invalidateModSummaryCache
return preload
+-- When changing the DynFlags, we want the changes to apply to future
+-- loads, but without completely discarding the program. But the
+-- DynFlags are cached in each ModSummary in the hsc_mod_graph, so
+-- after a change to DynFlags, the changes would apply to new modules
+-- but not existing modules; this seems undesirable.
+--
+-- Furthermore, the GHC API client might expect that changing
+-- log_action would affect future compilation messages, but for those
+-- modules we have cached ModSummaries for, we'll continue to use the
+-- old log_action. This is definitely wrong (#7478).
+--
+-- Hence, we invalidate the ModSummary cache after changing the
+-- DynFlags. We do this by tweaking the date on each ModSummary, so
+-- that the next downsweep will think that all the files have changed
+-- and preprocess them again. This won't necessarily cause everything
+-- to be recompiled, because by the time we check whether we need to
+-- recopmile a module, we'll have re-summarised the module and have a
+-- correct ModSummary.
+--
+invalidateModSummaryCache :: GhcMonad m => m ()
+invalidateModSummaryCache =
+ modifySession $ \h -> h { hsc_mod_graph = map inval (hsc_mod_graph h) }
+ where
+ inval ms = ms { ms_hs_date = addUTCTime (-1) (ms_hs_date ms) }
+
-- | Returns the program 'DynFlags'.
getProgramDynFlags :: GhcMonad m => m DynFlags
getProgramDynFlags = getSessionDynFlags
--
GitLab