#8714: ExistentialQuantification plus DeriveDataTypeable leads to core lint error -------------------------------------+---------------------------------- Reporter: CoreyOConnor | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: x86_64 (amd64) Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+---------------------------------- Comment (by monoidal): Here's a simpler version, compiling `-O -dcore-lint` gives an error {{{ {-# LANGUAGE ExistentialQuantification #-} module Main where data HLState = forall a. HLState (a -> a) !a data BufferImpl = FBufferData !HLState focusAst :: BufferImpl -> HLState focusAst (FBufferData (HLState f x)) = HLState f (f x) main = return () }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8714#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler