[commit: vector] simd: Comment out the NFData instance for mutable boxed vectors for now (3247dd1)

[Geoffrey Mainland]

Repository : http://darcs.haskell.org/ghc.git/

On branch  : simd

http://hackage.haskell.org/trac/ghc/changeset/3247dd115fea8bd380762c9d0030f325f2a3e260

>---------------------------------------------------------------

commit 3247dd115fea8bd380762c9d0030f325f2a3e260
Author: Roman Leshchinskiy <rl at cse.unsw.edu.au>
Date:   Sun Jan 29 12:14:29 2012 +0000

    Comment out the NFData instance for mutable boxed vectors for now

>---------------------------------------------------------------

 Data/Vector/Mutable.hs |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/Data/Vector/Mutable.hs b/Data/Vector/Mutable.hs
index 6168bea..e896f3a 100644
--- a/Data/Vector/Mutable.hs
+++ b/Data/Vector/Mutable.hs
@@ -72,12 +72,15 @@ data MVector s a = MVector {-# UNPACK #-} !Int
 type IOVector = MVector RealWorld
 type STVector s = MVector s
 
+-- NOTE: This seems unsafe, see http://trac.haskell.org/vector/ticket/54
+{-
 instance NFData a => NFData (MVector s a) where
     rnf (MVector i n arr) = unsafeInlineST $ force i
         where
           force !ix | ix < n    = do x <- readArray arr ix
                                      rnf x `seq` force (ix+1)
                     | otherwise = return ()
+-}
 
 instance G.MVector MVector a where
   {-# INLINE basicLength #-}