#11172: Turning on optimisations produces SEGFAULT or Impossible case alternative -------------------------------------+------------------------------------- Reporter: nh2 | Owner: bgamari Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 7.10.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): OK thanks to jscholl the bug is fixed. But I am still eager to know why this could give a **seg-fault**. An "impossible alternative" message perhaps; but a seg-fault is more worrying. Ben describes how to elicit the seg-fault in comment:17. (NB: you need the `segfault` branch of his repo.) jscholl: if you could repeat your amazing work on this variant, to make a much smaller seg-faulting test case, that would be amazing. (Of course it is always possible that there are two bugs, and I have only fixed one; another reason to investigate the seg-fault variant.) -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11172#comment:28 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler