#13803: Panic while forcing the thunk for TyThing IsFile (regression) -------------------------------------+------------------------------------- Reporter: inaki | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1-rc2 Resolution: | Keywords: hs-boot Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash or panic | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by ezyang): This is a family instance consistency check problem, as can be seen when you turn on tracing: {{{ checkForConflictsghc-stage2: panic! (the 'impossible' happened) (GHC version 8.3.20170517 for x86_64-unknown-linux): tcIfaceGlobal (local): not found }}} We begin checking for conflicts immediately before the panic. The problem is reminiscent of #11062 (fixed in 25b70a29f6236b591252bf5a361a1547f0ffee51). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13803#comment:11 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler