#8984: Improve output of failed GeneralizedNewtypeDeriving coercion due to type roles -------------------------------------+------------------------------------- Reporter: haasn | Owner: Type: feature | Status: new request | Milestone: Priority: normal | Version: 7.8.1 Component: Compiler | Keywords: (Type checker) | Architecture: Unknown/Multiple Resolution: | Difficulty: Unknown Operating System: | Blocked By: Unknown/Multiple | Related Tickets: Type of failure: | None/Unknown | Test Case: | Blocking: | Differential Revisions: | -------------------------------------+------------------------------------- Comment (by simonpj): Yes, I agree with your proposal. We should not blithely accept random (and perhaps unsatisfiable) equality constraints in `deriving` contexts. You can always specify the context with standalone-deriving if you want. Weill you execute on this? Simon -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8984#comment:7 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler