#13736: GHC panic with DataKinds and TypeOperators -------------------------------------+------------------------------------- Reporter: turion | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by turion: @@ -15,0 +15,10 @@ + + The error message is: + + + {{{ + ghc: panic! (the 'impossible' happened) + (GHC version 8.0.2 for x86_64-unknown-linux): + initTc: unsolved constraints + WC {wc_insol = [W] __aBJ :: t_aBI[tau:1] (CHoleCan: _)} + }}} New description: The following program causes a GHC panic: {{{#!hs {-# LANGUAGE DataKinds #-} {-# LANGUAGE TypeOperators #-} {-# LANGUAGE KindSignatures #-} import GHC.TypeLits data Proxy (n :: Nat) = Proxy data Foo a = Foo a foo :: Foo (Proxy (2 * 2)) foo = Foo _ }}} The error message is: {{{ ghc: panic! (the 'impossible' happened) (GHC version 8.0.2 for x86_64-unknown-linux): initTc: unsolved constraints WC {wc_insol = [W] __aBJ :: t_aBI[tau:1] (CHoleCan: _)} }}} -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13736#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler