[GHC] #8834: 64-bit windows cabal.exe segfaults in GC

[GHC]

#8834: 64-bit windows cabal.exe segfaults in GC
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        Reporter:  awson          |            Owner:
            Type:  bug            |           Status:  patch
        Priority:  highest        |        Milestone:  7.8.1
       Component:  Compiler       |          Version:  7.8.1-rc2
      Resolution:                 |         Keywords:
Operating System:  Windows        |     Architecture:  x86_64 (amd64)
 Type of failure:  Runtime crash  |       Difficulty:  Unknown
       Test Case:                 |       Blocked By:
        Blocking:                 |  Related Tickets:
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Comment (by thoughtpolice):

 I can confirm Kyril's example above works properly and produces the
 segfault as well. Here's my updated version:

 {{{#!haskell
 module Main (main) where

 import Prelude hiding (null, take, drop)
 import Data.ByteString hiding (elemIndex)
 import qualified Data.ByteString as B
 import Data.ByteString.Internal
 import Data.Word

 import Foreign

 elemIndex1 :: Word8 -> ByteString -> Maybe Int
 elemIndex1 c (PS x s l) = inlinePerformIO $ withForeignPtr x $ \p -> do
     let p' = p `plusPtr` s
     q <- memchr p' c (fromIntegral l)
     return $! if q == nullPtr then Nothing else Just $! q `minusPtr` p'
 {-# INLINE elemIndex1 #-}

 elemIndex :: Char -> ByteString -> Maybe Int
 elemIndex = elemIndex1 . c2w
 {-# INLINE elemIndex #-}

 lines1 :: ByteString -> [ByteString]
 lines1 ps
     | null ps = []
     | otherwise = case search ps of
              Nothing -> [ps]
              Just n  -> take n ps : lines1 (drop (n+1) ps)
     where search = elemIndex '\n'


 main = do
   f <- B.readFile "00-index.cache"
   print (Prelude.length $ lines1 f)
 }}}

 You can grab the `00-index.cache` file from
 `/c/Users/$USER/AppData/Roaming/cabal/packages/hackage.haskell.org/00-index.cache`

 I'm investigating reverting the PAP patch (still building).

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8834#comment:29>
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