check for ClosedHandle in read/write operations on DuplexHandles (#4808)

[ghc-base.git] / Debug / Trace.hs

diff --git a/Debug/Trace.hs b/Debug/Trace.hs
index accf247..742044e 100644 (file)
--- a/Debug/Trace.hs
+++ b/Debug/Trace.hs
@@ -13,9 +13,10 @@
 -----------------------------------------------------------------------------
 
 module Debug.Trace (
-       -- * Tracing
-       putTraceMsg,      -- :: String -> IO ()
-       trace             -- :: String -> a -> a
+        -- * Tracing
+        putTraceMsg,      -- :: String -> IO ()
+        trace,            -- :: String -> a -> a
+        traceShow
   ) where
 
 import Prelude
@@ -40,7 +41,9 @@ putTraceMsg msg = do
      withCString msg  $ \cmsg ->
       debugBelch cfmt cmsg
 
-foreign import ccall unsafe "RtsMessages.h debugBelch"
+-- don't use debugBelch() directly, because we cannot call varargs functions
+-- using the FFI.
+foreign import ccall unsafe "HsBase.h debugBelch2"
    debugBelch :: CString -> CString -> IO ()
 #endif