[GHC] #10577: Use empty cases where appropriate when deriving instances for empty types

[GHC]

#10577: Use empty cases where appropriate when deriving instances for empty types
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        Reporter:  rwbarton          |                   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:
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Comment (by osa1):

 One thing to note: We have two ways to derive instances, using `deriving
 (..)` syntax and StandaloneDeriving. If we want to make changes described
 here and also keep this two methods of instance deriving consistent with
 each other(currently they're not), it means breaking change.

 IMHO, StandaloneDeriving and `deriving (..)` should work the same, so we
 should either do this breaking change or merge
 https://phabricator.haskell.org/D978.

 Also, I'm not sure how relevant it is, but `Data.Void.Void`s methods are
 currently not forcing the arguments.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10577#comment:2>
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