#8225: Type Nats cause crash if GHC.TypeLits not imported ----------------------------------+------------------------------- Reporter: MikeIzbicki | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: GHCi crash Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ----------------------------------+------------------------------- If I create a file "test.hs" with the following code: {{{ data Poly (a::a) x = undefined :: Poly 1 }}} when I load it into ghci, I get the error message: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.6.3 for x86_64-unknown-linux): lookupVers2 <<details unavailable>> Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} Now, modify the file into {{{ import GHC.TypeLits data Poly (a::a) x = undefined :: Poly 1 }}} and no error is reported. What's weird is that if we now modify the file back to the original, then the error is still not reported. Everything compiles perfectly fine. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8225 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler