[GHC] #16140: Cannot create type synonym for quantified constraint without ImpredicativeTypes

[GHC]

#16140: Cannot create type synonym for quantified constraint without
ImpredicativeTypes
-------------------------------------+-------------------------------------
        Reporter:  Ashley Yakeley    |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.3
      Resolution:                    |             Keywords:
                                     |  QuantifiedConstraints,
                                     |  ImpredicativeTypes
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 simonpj):

 > It's possible that this is just #16059 manifesting in a different way,
 though.

 Sounds likely to me.  And we have a plan for #16059, in comment:4.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16140#comment:7>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler