#12109: Matching on pattern synonym succeeds compiled with ghc, fails with ghci -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple PatternSynonyms | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- A file `/tmp/test.hs` {{{#!hs {-# Language PatternSynonyms, ViewPatterns #-} pattern Parsed x = [(x, "")] pattern Read a <- (reads -> Parsed a) main = do let Read x = "420" print (x::Int) }}} {{{ $ ghc -ignore-dot-ghci /tmp/test.hs && /tmp/test 420 }}} fails with ghci {{{#!hs $ ghci -ignore-dot-ghci /tmp/test.hs GHCi, version 8.0.0.20160511: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( /tmp/test.hs, interpreted ) ghc: panic! (the 'impossible' happened) (GHC version 8.0.0.20160511 for x86_64-unknown-linux): kindPrimRep.go rep_a1XC Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug

}}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12109 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler