#10598: DeriveAnyClass and GND don't work well together -------------------------------------+------------------------------------- Reporter: osa1 | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.11 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: None/Unknown | Unknown/Multiple Blocked By: | Test Case: Related Tickets: | Blocking: | Differential Revisions: -------------------------------------+------------------------------------- Comment (by kosmikus): Yes, I think it makes sense to require at least any sort of default definition for all class methods, regardless of whether it is a normal default or a generic default. It might also be sensible to take MINIMAL pragmas into account. If an explicit non-empty MINIMAL pragma is specified, then I think the intent of the author is to say that it doesn't make sense to give an empty class instance, and similarly, it would then also not make sense to derive it. But I'm open to suggestions. Even if we allow DeriveAnyClass for classes that have e.g. mutually recursive defaults and a non-empty MINIMAL pragma, I guess we'd at least still get a warning reported for the derived instance. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10598#comment:10 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler