#13750: GHC produces incorrect coercions in hairy code -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.2.2 Component: Compiler | Version: 8.2.1-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: #13429 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): Well this is embarrassing. I did take a quick look. The test program is littered with `unsafeCoerce` which makes it harder to determine where things actually go wrong. I still think the "decideQuantification" patch is fine; I think it is just exposing bugs elsewhere. I discovered that (like #13429), adding `-fno-specialise` (to switch off the specialiser) makes it work again. So that may be a workaround for Andres. I'm not against reverting the "decideQauntification" patch as an expedient way to make the release work; but that would re-introduce the bugs that the patch cured. I'm on holiday now for a week, I'm afraid. It'd be great if someone was able to characterise more precisely what is going wrong. At the moment I have no clue. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13750#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler