#12634: Panic with piResultTys1 -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Compile-time Unknown/Multiple | crash Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- {{{ {-# LANGUAGE DataKinds #-} {-# LANGUAGE ScopedTypeVariables #-} twacePowDec :: t m' r -> t m r twacePowDec = undefined data Bench a bench :: (a -> b) -> a -> Bench params bench f = undefined bench_twacePow :: forall t m m' r . _ => t m' r -> Bench '(t,m,m',r) bench_twacePow = bench (twacePowDec :: t m' r -> t m r) }}} produces (in GHCi): {{{ GHCi, version 8.0.1: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( Bug.hs, interpreted ) Bug.hs:13:58: error: • Expected a type, but ‘'(t, m, m', r)’ has kind ‘(k1 -> k2 -> *, k0, k1, k2)’ • In the first argument of ‘Bench’, namely ‘'(t, m, m', r)’ In the type ‘t m' r -> Bench '(t, m, m', r)’ Bug.hs:14:52: error: • Expected kind ‘k1’, but ‘m’ has kind ‘k0’ • In the first argument of ‘t’, namely ‘m’ In an expression type signature: t m' r -> t m r In the first argument of ‘bench’, namely ‘(twacePowDec :: t m' r -> t m r)’ • Relevant bindings includeghc: panic! (the 'impossible' happened) (GHC version 8.0.1 for x86_64-unknown-linux): piResultTys1 k_a18K[tau:3] [m'_a17U[sk], r_a17V[sk]] }}} The intent was to use this code with `-XPartialTypeSignatures`, but the bug occurs with or without that extension. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12634 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler