#11172: Turning on optimisations produces Impossible case alternative -------------------------------------+------------------------------------- Reporter: nh2 | Owner: Type: bug | Status: new Priority: normal | 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 nh2): Simon, for reproducing with GHC 8 HEAD it seems a little more effort is needed, but it seems to work for me this way: * From my repro, use the `ghc-8-head` branch instead (https://github.com/fpco/impossible-case-alternative- repro/tree/ghc-8-head); use `cabal install --with-ghc=...` as you did, it will now break at compiling `aeson` because that's not yet GHC 8 ready; ignore that issue * Use my custom `aeson` version from https://github.com/nh2/aeson/tree/ghc-8-head-workaround, which should compile with `cabal install --with-ghc=...` Then you should be able to `ghc --make` with GHC head. Please let me know if it works! -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11172#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler