[commit: ghc] wip/andrey/windows-doc: Don't overwrite the set log_action when using --interactive (10faf44)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/andrey/windows-doc
Link       : http://ghc.haskell.org/trac/ghc/changeset/10faf44d97095b2f8516b6d449d266f6889dcd70/ghc

>---------------------------------------------------------------

commit 10faf44d97095b2f8516b6d449d266f6889dcd70
Author: Matthew Pickering <matthewtpickering at gmail.com>
Date:   Sun Jan 20 20:58:01 2019 -0500

    Don't overwrite the set log_action when using --interactive
    
    -ddump-json didn't work with --interactive as --interactive overwrote
    the log_action in terms of defaultLogAction.
    
    Reviewers: bgamari
    
    Subscribers: rwbarton, thomie, carter
    
    GHC Trac Issues: #14078
    
    Differential Revision: https://phabricator.haskell.org/D4533


>---------------------------------------------------------------

10faf44d97095b2f8516b6d449d266f6889dcd70
 ghc/GHCi/UI.hs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/ghc/GHCi/UI.hs b/ghc/GHCi/UI.hs
index 10ca511..abb3d78 100644
--- a/ghc/GHCi/UI.hs
+++ b/ghc/GHCi/UI.hs
@@ -445,7 +445,10 @@ interactiveUI config srcs maybe_exprs = do
    lastErrLocationsRef <- liftIO $ newIORef []
    progDynFlags <- GHC.getProgramDynFlags
    _ <- GHC.setProgramDynFlags $
-      progDynFlags { log_action = ghciLogAction lastErrLocationsRef }
+      -- Ensure we don't override the user's log action lest we break
+      -- -ddump-json (#14078)
+      progDynFlags { log_action = ghciLogAction (log_action progDynFlags)
+                                                lastErrLocationsRef }
 
    when (isNothing maybe_exprs) $ do
         -- Only for GHCi (not runghc and ghc -e):
@@ -536,9 +539,10 @@ resetLastErrorLocations = do
     st <- getGHCiState
     liftIO $ writeIORef (lastErrorLocations st) []
 
-ghciLogAction :: IORef [(FastString, Int)] ->  LogAction
-ghciLogAction lastErrLocations dflags flag severity srcSpan style msg = do
-    defaultLogAction dflags flag severity srcSpan style msg
+ghciLogAction :: LogAction -> IORef [(FastString, Int)] ->  LogAction
+ghciLogAction old_log_action lastErrLocations
+              dflags flag severity srcSpan style msg = do
+    old_log_action dflags flag severity srcSpan style msg
     case severity of
         SevError -> case srcSpan of
             RealSrcSpan rsp -> modifyIORef lastErrLocations