Fix deadlock on second call to newSession

[ghc-hetmet.git] / compiler / main / GHC.hs

diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index 6295d7d..eabcafc 100644 (file)
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -333,7 +333,7 @@ newSession :: GhcMode -> Maybe FilePath -> IO Session
 newSession mode mb_top_dir = do
   -- catch ^C
   main_thread <- myThreadId
-  putMVar interruptTargetThread [main_thread]
+  modifyMVar_ interruptTargetThread (return . (main_thread :))
   installSignalHandlers
 
   dflags0 <- initSysTools mb_top_dir defaultDynFlags