2 files changed, 10 insertions, 9 deletions
diff --git a/haddock-test/src/Test/Haddock/Config.hs b/haddock-test/src/Test/Haddock/Config.hs
index 51032a3a..6447361f 100644
--- a/haddock-test/src/Test/Haddock/Config.hs
+++ b/haddock-test/src/Test/Haddock/Config.hs
@@ -196,6 +196,7 @@ loadConfig ccfg dcfg flags files = do
 
     cfgHaddockArgs <- liftM concat . sequence $
         [ pure ["--no-warnings"]
+        , pure ["--bypass-interface-version-check"]
         , pure ["--odir=" ++ dcfgOutDir dcfg]
         , pure ["--optghc=-w"]
         , pure ["--optghc=-hide-all-packages"]
@@ -223,13 +224,13 @@ printVersions env haddockPath = do
         { pcEnv = Just env
         , pcArgs = ["--version"]
         }
-    waitForSuccess "Failed to run `haddock --version`" handleHaddock
+    void $ waitForSuccess "Failed to run `haddock --version`" stderr handleHaddock
 
     handleGhc <- runProcess' haddockPath $ processConfig
         { pcEnv = Just env
         , pcArgs = ["--ghc-version"]
         }
-    waitForSuccess "Failed to run `haddock --ghc-version`" handleGhc
+    void $ waitForSuccess "Failed to run `haddock --ghc-version`" stderr handleGhc
 
 
 baseDependencies :: FilePath -> IO [String]
diff --git a/haddock-test/src/Test/Haddock/Process.hs b/haddock-test/src/Test/Haddock/Process.hs
index 52bf9533..a6cab9ac 100644
--- a/haddock-test/src/Test/Haddock/Process.hs
+++ b/haddock-test/src/Test/Haddock/Process.hs
@@ -40,10 +40,10 @@ runProcess' :: FilePath -> ProcessConfig -> IO ProcessHandle
 runProcess' path (ProcessConfig { .. }) = runProcess
     path pcArgs pcWorkDir pcEnv pcStdIn pcStdOut pcStdErr
 
-
-waitForSuccess :: String -> ProcessHandle -> IO ()
-waitForSuccess msg handle = do
-    result <- waitForProcess handle
-    unless (result == ExitSuccess) $ do
-        hPutStrLn stderr $ msg
-        exitFailure
+-- | Wait for a process to finish running. If it ends up failing, print out the
+-- error message.
+waitForSuccess :: String -> Handle -> ProcessHandle -> IO Bool
+waitForSuccess msg out handle = do
+    succeeded <- fmap (== ExitSuccess) $ waitForProcess handle
+    unless succeeded $ hPutStrLn out msg
+    pure succeeded