#8132: Warning for Typeable instances misplaced -------------------------------------------------+------------------------- Reporter: scottgw | Owner: Type: bug | dreixel Priority: normal | Status: new Component: Compiler | Milestone: Resolution: | Version: 7.7 Operating System: Unknown/Multiple | Keywords: Type of failure: Incorrect warning at | Architecture: compile-time | Unknown/Multiple Test Case: | Difficulty: Blocking: | Unknown | Blocked By: | Related Tickets: -------------------------------------------------+------------------------- Comment (by scottgw): Maybe I am misunderstanding but it seems like backwards compatibility is already broken, twice: 1. Backwards compatibility is already broken by changing `typeOf` to `typeRep` in Typeable. So anyone coming from 7.6 is already going to have a compile error on any manually defined instance. 2. Ignoring that, backwards compatibility is already broken by ignoring manually defined instances. Making this an error just turns a 3 step fixing process (typeOf -> typeRep, discover complaints about missing instance scratch head, use deriving Typeable) into a 2 step one (typeOf -> typeRep, use deriving Typeable). The other solution is to not have it ignore the hand written instances, which would also bring it back down to even 1 step (typeOf -> typeRep). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8132#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler