#12101: Regression: Pattern synonyms make GHCi 8.0.1 crash -------------------------------------+------------------------------------- Reporter: int-index | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: GHCi crash Unknown/Multiple | Test Case: | Blocked By: https://gist.githubusercontent.com | /int- | index/17dfb68fd97f724aef2849d0defae0d6/raw/3dab71756bbafa197b93170310ccabfea8c92120/M.hs| Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- This code: {{{ {-# LANGUAGE PatternSynonyms #-} data T = C pattern P :: T pattern P = C pattern P' :: T pattern P' = P }}} compiles fine with both GHC 7.10.3 and 8.0.1. However, if you try to load it into GHCi 8.0.1, it panics: {{{ GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help Prelude> :l M.hs [1 of 1] Compiling Main ( M.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): kindPrimRep.go rep_a18a Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} GHCi 7.10.3 does not crash, therefore it's a regression: {{{ GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help Prelude> :l M.hs [1 of 1] Compiling Main ( M.hs, interpreted ) Ok, modules loaded: Main. *Main> }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12101 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler