#15764: GHC panic from PolyKinds + DataKinds -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.6.1 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Playing around with GhcKinds/KindInference/Examples gives me a GHC panic {{{#!hs -- https://ghc.haskell.org/trac/ghc/wiki/GhcKinds/KindInference/Examples?versio... {-# Language PolyKinds #-} {-# Language KindSignatures #-} {-# Language DataKinds #-} import Data.Kind import Data.Proxy import GHC.TypeLits class C6 (k :: Type) (a :: k) (b :: Proxy (a :: k)) where type T6 (proxy :: Proxy '(k, b)) }}} on an out of date version of HEAD I get {{{ $ ghci -ignore-dot-ghci 519.hs GHCi, version 8.7.20180828: http://www.haskell.org/ghc/ :? for help [1 of 1] Compiling Main ( 519.hs, interpreted ) ghc-stage2: panic! (the 'impossible' happened) (GHC version 8.7.20180828 for x86_64-unknown-linux): ASSERT failed! 1 0 k_a1FD[tau:0] Proxy a_a1EN[sk:1] Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/utils/Outputable.hs:1160:37 in ghc:Outputable pprPanic, called at compiler/utils/Outputable.hs:1219:5 in ghc:Outputable assertPprPanic, called at compiler/typecheck/TcMType.hs:768:54 in ghc:TcMType Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
}}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15764 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler