#9575: -XAutoDeriveTypeable fails to generate instances -------------------------------------+------------------------------------- Reporter: hvr | Owner: Type: bug | Status: new Priority: high | Milestone: 7.8.4 Component: Compiler | Version: 7.8.3 Keywords: | Operating System: Architecture: Unknown/Multiple | Unknown/Multiple Difficulty: Unknown | Type of failure: Blocked By: | None/Unknown Related Tickets: | Test Case: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- The following doesn't compile with GHC 7.8.3, but works with GHC HEAD. I couldn't find a matching ticket, so I don't know if this was fixed knowingly or not... {{{#!hs {-# LANGUAGE AutoDeriveTypeable #-} import Data.Typeable (Typeable) data T1 = C1 Int deriving (Eq,Ord) tvoid :: Typeable a => a -> IO () tvoid _ = return () main :: IO () main = tvoid (C1 0) }}} ...fails for GHC 7.8.3 with {{{ No instance for (Typeable T1) arising from a use of ‘tvoid’ In the expression: tvoid (C1 0) In an equation for ‘main’: main = tvoid (C1 0) }}} I'm marking this with high priority, as it makes `-XAutoDeriveTypeable` unusable on GHC 7.8.3 as it stands. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9575 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler