#9001: unexpected runtime crash -------------------------------------+------------------------------------ Reporter: jwlato | Owner: simonmar Type: bug | Status: new Priority: normal | Milestone: Component: Runtime System | Version: 7.8.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Runtime crash | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------ Comment (by monoidal): I've reduced the testcase, but it got messy; compiling `ghc-7.8.2 X.hs` and running should give an internal error: {{{ {-# LANGUAGE RankNTypes #-} newtype FMList = FM {unFM :: forall m. (m -> m -> m) -> m -> m} main = print $ build $ delete $ FM (\_ x -> x) delete l = FM (\map x -> unFM l const (const undefined) `seq` unFM (delete (dr l)) map x `seq` x) build t = unFM t (.) (+1) 0 dr t = FM $ \_ g -> unFM t (.) (const g) undefined }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9001#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler