[GHC] #7401: Can't derive instance for Eq when datatype has no constructor, while it is trivial do do so.

[GHC]

#7401: Can't derive instance for Eq when datatype has no constructor, while it is
trivial do do so.
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        Reporter:  jpbernardy                 |            Owner:  monoidal
            Type:  feature request            |           Status:  new
        Priority:  normal                     |        Milestone:  7.8.1
       Component:  Compiler                   |          Version:  7.6.1
      Resolution:                             |         Keywords:  deriving
Operating System:  Unknown/Multiple           |     Architecture:
 Type of failure:  GHC rejects valid program  |  Unknown/Multiple
       Test Case:                             |       Difficulty:  Unknown
        Blocking:                             |       Blocked By:
                                              |  Related Tickets:
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Comment (by goldfire):

 Good point about the fact that H2010 does '''not''' have empty data decls.
 But, then, GHC's interpretation of H2010 is incorrect, as setting H2010 as
 the language turns on `EmptyDataDecls`. Personally, I don't love straying
 from the standard, but it may be best not to unnecessarily break code here
 by "fixing" this deviation from the standard.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/7401#comment:15>
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