mark System.IO.openTempFile as non-portable in haddocks

diff --git a/System/IO.hs b/System/IO.hs
index cebaa98..0179d8d 100644 (file)
--- a/System/IO.hs
+++ b/System/IO.hs
@@ -155,7 +155,7 @@ module System.IO (
     hGetBufNonBlocking,               -- :: Handle -> Ptr a -> Int -> IO Int
 #endif
 
-    -- * Temporary files
+    -- * Temporary files (not portable: GHC only)
 
 #ifdef __GLASGOW_HASKELL__
     openTempFile,