[GHC] #10598: DeriveAnyClass and GND don't work well together

[GHC]

#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:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |               Test Case:
      Blocked By:                    |                Blocking:
 Related Tickets:                    |  Differential Revisions:
-------------------------------------+-------------------------------------

Comment (by kosmikus):

 I think the confusion is understandable, because a large design space is
 being discussed here.

 The issue as reported is mainly about interaction between
 `GeneralizedNewtypeDeriving` and `DeriveAnyClass`. There are four options
 specified here:
 https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/GenericDeriving#InteractionwithGeneralizedNewtypeDeriving

 All four have disadvantages, and unfortunately the document does not say
 which of the four options actually has been implemented.

 It seems from the current behaviour of GHC like the implementation is
 along the lines of option 2 (and perhaps 3). However, even then we still
 have the fact that the error messages don't seem to properly reflect what
 is going on.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10598#comment:18>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler