#7536: Panic with TypeFamilies and FlexibleInstances -------------------------------+-------------------------------------------- Reporter: snowleopard | Owner: Type: bug | Status: new Priority: normal | Component: Compiler Version: 7.6.1 | Keywords: Os: Unknown/Multiple | Architecture: Unknown/Multiple Failure: Compile-time crash | Blockedby: Blocking: | Related: -------------------------------+-------------------------------------------- The code below brings GHC to panic.
{{{ {-# LANGUAGE TypeFamilies, FlexibleInstances #-} module Bug where type Node v = Int class Predicate a where type Var a variable :: Var a -> a instance Predicate (Node v) where type Var (Node v) = v variable = undefined }}} Panic details: {{{ ghc: panic! (the 'impossible' happened) (GHC version 7.4.2 for i386-unknown-mingw32): tcTyVarDetails ( v{tv aa3} [tv] :: ghc-prim:GHC.Prim.*{(w) tc 34d} ) }}} Can be reproduced on GHC versions 7.4.2 and 7.6.1. Possibly, a duplicate of [http://hackage.haskell.org/trac/ghc/ticket/7458], but difficult to tell without additional info on the latter. -- Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7536> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler _______________________________________________ Glasgow-haskell-bugs mailing list Glasgow-haskell-bugs@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-bugs