#14241: Pattern synonyms defined through other pattern synonyms produce `impossible happened` ---------------------------------------+------------------------------- Reporter: Heimdell | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: PatternSynonyms | Operating System: Linux Architecture: x86_64 (amd64) | Type of failure: GHCi crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: ---------------------------------------+------------------------------- This module content (Bug.hs) {{{#!hs {-# language PatternSynonyms #-} data A a = A a pattern B a = A a pattern C a = B a }}} causes ghci/runhaskell to fail: {{{

:l Bug [1 of 1] Compiling Main ( Bug.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): kindPrimRep.go rep_a1r0

Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug }}} When using ghc everything compiles and even works, so adding the code {{{#!hs main = do let C a = A 1 print a }}} produced executable that prints "1". -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14241 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler