[GHC] #14450: GHCi spins forever

[GHC]

#14450: GHCi spins forever
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  closed
        Priority:  high              |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  8.2.1
      Resolution:  fixed             |             Keywords:  TypeInType,
                                     |  PolyKinds
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Compile-time      |            Test Case:
  performance bug                    |  polykinds/T14450
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by Iceland_jack):

 Is this an instance of the same bug? Loops on 8.3.20170920 and 8.2

 {{{#!hs
 {-# Language KindSignatures, TypeOperators, PolyKinds, DataKinds,
 TypeInType, TypeFamilies, AllowAmbiguousTypes #-}

 import Data.Kind

 type a-->b = (a, b) -> Type

 type Cat k = k -> k -> Type

 class F (f::k-->k') where
   type D f :: Cat k
   type C f :: Cat k'
   f :: D f a a' -> C d (App f a) (App f a')

 data DupSym0 :: a --> (a, a)

 type family
   App (f::a-->b) (x::a) :: b where
   App DupSym0 a = '(a, a)

 instance F DupSym0 where
   type D DupSym0 = (->)
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14450#comment:9>
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