[GHC] #14584: Core Lint error

[GHC]

#14584: Core Lint error
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.1
      Resolution:                    |             Keywords:  TypeInType,
                                     |  DeferredTypeErrors
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by monoidal):

 I've reduced to:

 {{{
 {-# Language PartialTypeSignatures #-}
 {-# Language KindSignatures #-}
 {-# Language PolyKinds #-}
 {-# Language ScopedTypeVariables #-}
 {-# Language AllowAmbiguousTypes #-}
 {-# Language TypeApplications #-}

 data Sing (a :: *) = X

 f :: forall m a. Sing a
 f = X @m :: Sing _
 }}}

 and as previously `ghci -ignore-dot-ghci -fdefer-type-errors -dcore-lint
 146-bug.hs` gives a Core Lint error; I've checked 8.2.1 but not HEAD.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14584#comment:3>
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