
#11027: GHC API panic (evaluated the place holder for a PostTcType) -------------------------------------+------------------------------------- Reporter: rubik | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: GHC API | Version: 7.8.4 Keywords: undefined, | Operating System: Linux place holder, posttctype | Architecture: x86_64 | Type of failure: Runtime crash (amd64) | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- The same code that works for GHC 7.10.2 blows up on GHC 7.8.4, with errors like {{{ test/ArgonSpec.hs:104: (best-effort) 6) Argon.analyze accounts for && operator uncaught exception: GhcException (argon-test: panic! (the 'impossible' happened) (GHC version 7.8.4 for x86_64-unknown-linux): fixity Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug ) test/ArgonSpec.hs:106: (best-effort) 7) Argon.analyze counts everything in a real example uncaught exception: GhcException (argon-test: panic! (the 'impossible' happened) (GHC version 7.8.4 for x86_64-unknown-linux): Evaluated the place holder for a PostTcType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug ) }}} The responsible module is [https://github.com/rubik/argon/blob/master/src/Argon/Visitor.hs] and in particular (I think): {{{ visitExp :: Exp -> Int visitExp (GHC.HsIf {}) = 1 visitExp (GHC.HsMultiIf _ alts) = length alts - 1 visitExp (GHC.HsLamCase _ alts) = length (GHC.mg_alts alts) - 1 visitExp (GHC.HsCase _ alts) = length (GHC.mg_alts alts) - 1 visitExp _ = 0 visitOp :: Exp -> Int visitOp (GHC.OpApp _ (GHC.L _ (GHC.HsVar op)) _ _) = case getName op of "||" -> 1 "&&" -> 1 _ -> 0 visitOp _ = 0 }}} somehow, even if I use wildcards, the first arguments of the type constructors gets evaluated and since it's undefined GHC crashes. What am I supposed to do? The documentation does not say anything on the matter. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11027 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler