[GHC] #13272: DeriveAnyClass regression involving a rigid type variable

[GHC]

#13272: DeriveAnyClass regression involving a rigid type variable
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.1
  checker)                           |
      Resolution:                    |             Keywords:  Generics
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:                    |
-------------------------------------+-------------------------------------

Comment (by RyanGlScott):

 It's still a bit of a bummer that `DeriveAnyClass` has become //worse//.
 Perhaps we should just revert 639e702b6129f501c539b158b982ed8489e3d09c for
 now?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13272#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler