[GHC] #15712: GHC panic with -XDerivingVia

[GHC]

#15712: GHC panic with -XDerivingVia
-------------------------------------+-------------------------------------
        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:  DerivingVia
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 With HEAD, and GHC 8.6, for the code in comment:2 I get
 {{{
 T15712.hs:20:16: error:
     • Expecting one more argument to ‘GEndo’
       Expected kind ‘* -> *’, but ‘GEndo’ has kind ‘(* -> *) -> * -> *’
     • In the first argument of ‘Codensity’, namely ‘GEndo’
       In the newtype declaration for ‘LogicT’
    |
 20 |     (Codensity GEndo)
    |                ^^^^^
 }}}
 Can others confirm?  If so, could someone add a regression test and close?
 Thanks!

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15712#comment:3>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler