[GHC] #13154: Standalone-derived anyclass instances aren't as permissive as empty instances

[GHC]

#13154: Standalone-derived anyclass instances aren't as permissive as empty
instances
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  RyanGlScott
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      Resolution:                    |             Keywords:  deriving
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------
Changes (by RyanGlScott):

 * owner:  (none) => RyanGlScott


Comment:

 See also commits:

 * a4f347c23ed926c24d178fec54c27d94f1fae0e4 (`Split out
 inferConstraintsDataConArgs from inferConstraints`)
 * ed7a830de6a2ea74dd6bb81f8ec55b9fe0b52f28 (`Use a ReaderT in TcDeriv to
 avoid some tedious plumbing`)
 * 9cb289abc582c9eb8337a2621baf58e35feeff46 (`Remove hack put in place for
 #12512`)

 Which have made progress towards fixing this ticket (but on whose commit
 messages I forgot to mention it).

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13154#comment:10>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler