Compile without warnings in 7.4 and 7.6

System/IO/Pipeline.hs

@@ -2,9 +2,15 @@
 
 A pipeline closes itself when a read or write causes an error, so you can detect a broken pipeline by checking isClosed.  It also closes itself when garbage collected, or you can close it explicitly. -}
 
-{-# LANGUAGE DoRec, RecordWildCards, NamedFieldPuns, ScopedTypeVariables #-}
+{-# LANGUAGE RecordWildCards, NamedFieldPuns, ScopedTypeVariables #-}
 {-# LANGUAGE CPP #-}
 
+#if (__GLASGOW_HASKELL__ >= 706)
+{-# LANGUAGE RecursiveDo #-}
+#else
+{-# LANGUAGE DoRec #-}
+#endif
+
 module System.IO.Pipeline (
 	IOE,
 	-- * IOStream