[GHC] #16008: GHC HEAD type family regression involving invisible arguments

[GHC]

#16008: GHC HEAD type family regression involving invisible arguments
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.8.1
       Component:  Compiler (Type    |              Version:  8.7
  checker)                           |             Keywords:  TypeFamilies,
      Resolution:                    |  TypeInType
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):

 A workaround is to manually give `SD` a kind ascription:

 {{{#!hs
 instance C (D a) where
   type S = (SD :: D a -> Type)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16008#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler