#8037: GHC panic when compiling unsafeCoerce ---------------------------------+------------------------------------ Reporter: ghc@… | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.1 Resolution: | Keywords: Operating System: MacOS X | Architecture: Unknown/Multiple Type of failure: None/Unknown | Difficulty: Unknown Test Case: | Blocked By: Blocking: | Related Tickets: ---------------------------------+------------------------------------ Changes (by monoidal): * status: infoneeded => new Comment: Great, I can now reproduce. I looked into internals of OpenGL and OpenGLRaw and here's a version which does not have the dependency. Compile with -O to get the panic, both 7.6 and HEAD. {{{ module Test where import Unsafe.Coerce import Foreign.Ptr import Foreign.C.Types import System.IO.Unsafe data D4 = D4 Double Double Double Double crash :: D4 -> IO () crash c = color (invalidCast c) invalidCast :: D4 -> Color3 CDouble invalidCast = unsafeCoerce class Color a where color :: a -> IO () colorv :: [a] -> IO () data Color3 a = Color3 !a !a !a instance ColorComponent a => Color (Color3 a) where color (Color3 r g b) = color3 r g b class ColorComponent a where color3 :: a -> a -> a -> IO () instance ColorComponent CDouble where color3 = g type Invoker a = FunPtr a -> a foreign import ccall dyn_g :: Invoker (CDouble -> CDouble -> CDouble -> IO ()) g :: CDouble -> CDouble -> CDouble -> IO () g = dyn_g ptr_g ptr_g :: FunPtr a ptr_g = unsafePerformIO undefined }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8037#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler