#13071: GHCi 8.0.1 panic with PatternSynonyms ----------------------------------------+------------------------------- Reporter: taktoa | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHCi | Version: 8.0.1 Keywords: PatternSynonyms | Operating System: Linux Architecture: Unknown/Multiple | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ----------------------------------------+------------------------------- Loading this code: {{{#!hs {-# LANGUAGE PatternSynonyms #-} data D1 = MkD1 () data D2 = MkD2 D1 pattern P1 x = MkD1 x pattern P2 x = MkD2 (P1 x) }}} in GHCi 8.0.1 results in the following panic: {{{ $ ghci Broken.hs GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Broken.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): kindPrimRep.go rep_a18s Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}} The unique name in the error message (`rep_a18s`) seems to be consistent between executions, but varies after `:reload`ing. The panic does not occur when the module is simply compiled with `ghc`; it only occurs when loaded into `ghci`. According to Gergő Érdi, who is CCed, the error does not occur in GHCi 7.10.3 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13071 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler