[GHC] #7898: Compiler diverges when compiling module BSP of frag-1.1.2

[GHC]

#7898: Compiler diverges when compiling module BSP of frag-1.1.2
-------------------------------+--------------------------------------------
Reporter:  tinctorius          |          Owner:                  
    Type:  bug                 |         Status:  new             
Priority:  normal              |      Component:  Compiler        
 Version:  7.6.3               |       Keywords:                  
      Os:  Unknown/Multiple    |   Architecture:  Unknown/Multiple
 Failure:  Compile-time crash  |      Blockedby:                  
Blocking:                      |        Related:                  
-------------------------------+--------------------------------------------
 GHC will get stuck when trying to compile
 [http://www.haskell.org/haskellwiki/Frag Frag]. Steps to reproduce:

  1. Get Frag 1.1.2 from the Darcs repository (`darcs get
 http://code.haskell.org/frag`), or from snowmantw's !GitHub fork (`git
 clone https://github.com/snowmantw/Frag.git`).
  1. Fix the code so it'll actually compile:
     {{{
 diff --git a/src/Textures.hs b/src/Textures.hs
 index 7383fd8..b5516a5 100644
 --- a/src/Textures.hs
 +++ b/src/Textures.hs
 @@ -10,6 +10,7 @@ import Graphics.UI.GLUT
  import TGA (readTga)
  import Data.Word (Word8)
  import Foreign.Marshal.Alloc (free)
 +import Control.Exception (catch, SomeException)


  -- read a list of images and returns a list of textures
 @@ -32,7 +33,8 @@ getAndCreateTexture fileName = do

  -- read the image data
  readImageC :: String -> IO (Maybe (Size, PixelData Word8))
 -readImageC path = catch (readTga path) (\_ -> do print ("missing texture:
 "++path)
 +readImageC path = catch (readTga path) (\e -> do print (e ::
 SomeException)
 +                                                 print ("missing texture:
 "++path)
                                                   return Nothing)

     }}}
  1. `cabal configure`
  1. `cabal build`

 GHC will get stuck on the module `BSP` and consume memory until it
 crashes. According to [https://github.com/snowmantw/Frag/issues/1 this
 ticket on the GitHub fork mentioned earlier], this problem only occurs
 with `-O2`.

 When I split the reading part of the module (`readBSP` and all functions
 it depends on), it crashed on that part. Will investigate further.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7898>
GHC <http://www.haskell.org/ghc/>
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