#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 simonpj): Yurgh. You are quite right. It's really hard to move on ''and'' maintain backwards compatibility! I'm open to advice. Two alternatives make sense to me: * Maintain total backward compat for a single release, by putting the new stuff in `Data.NewTypeable` for one release (with heavy deprecation messages), and ''then'' in 7.10 moving it to `Data.Typeable`, while making the old `Data.Typeable` into `Data.OldTypeable`. * Just make the breaking change now (which as you point out, we have already done in HEAD). In that case we should make manual `Typeable` instances an error right away. I'd prefer the latter. In practice each release of GHC does typically require some changes wrt base, and I doubt that 7.8 will be an exception to that. But I'm sensitive to what users want. Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8132#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler