#15434: DerivingVia (and perhaps even GND) works badly with DeriveGeneric -------------------------------------+------------------------------------- Reporter: konn | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler | Version: Resolution: | Keywords: deriving Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by RyanGlScott): * keywords: => deriving Comment: I'm not sure what the bug is here. You're explicitly requesting that you reuse the `Generic` instance for `Bad Foo`, and lo and behold, GHC gives you it. If you don't like this behavior, don't combine `DerivingVia` with `Generic`—the former wasn't meant to be combined with the latter (indeed, this code will give an error if combined with the `Safe` extension). -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15434#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler