#11334: GHC panic when calling typeOf on a promoted data constructor -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: bgamari Type: bug | Status: new Priority: highest | Milestone: 8.0.1 Component: Compiler (Type | Version: 8.0.1-rc1 checker) | Resolution: | Keywords: TypeInType Operating System: Unknown/Multiple | Architecture: Type of failure: Compile-time | Unknown/Multiple crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1757 Wiki Page: | -------------------------------------+------------------------------------- Comment (by goldfire): Oh dear. Something seems terribly terribly wrong. {{{#!hs newtype Compose (f :: k -> *) (g :: k1 -> k) (a :: k1) = Compose {getCompose :: f (g a)} }}} This gives `Compose :: forall k k1. (k -> *) -> (k1 -> k) -> k1 -> *`. But your code above has '''three''' `*`s passed to `Compose`. Somehow the third one is wrong. (I think the first two are correct, as set in `quantifyTyVars`. I'm unconvinced that `quantifyTyVars` is to blame.) GHC is getting duped into thinking `* :: * -> *`, which would, actually, make the `TYPE 'Lifted (TYPE 'Lifted *)` bit well kinded. I've no clue where this is going wrong, but it's going wrong rather spectacularly. My next step would be `-ddump-tc-trace -fprint-explicit- kinds` and search for the first occurrence of `Compose * * *`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11334#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler