#15038: Memory Corruption (strange closure type) -------------------------------------+------------------------------------- Reporter: andrewthad | Owner: (none) Type: bug | Status: new Priority: highest | Milestone: 8.6.1 Component: Compiler | Version: 8.4.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: #9718 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by andrewthad): Ömer, thanks for the excellent sleuthing and the very clear explanation of what had gone awry. It sounds like the crash I have been experiencing will be fixed in GHC 8.6 (and that someone may resolve the longstanding #9718). What I don’t fully grasp is the set of circumstances under which this error manifests itself. Based on my reading of the explanation, it seems like this would happen any time there was a pattern match on an unboxed sum in which none of the cases referenced a CAF. But that doesn’t seem right, because that would mean that this error would happen all the time. The reason I am interested in understanding this is because I would like to know if there is a subset of programs in which unboxed sums can safely be used. Or, as a library author, is it currently impossible to use unboxed sums in such a way that the end user cannot induce the failure case? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15038#comment:25 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler