[GHC] #14180: Strange/bad error message binding unboxed type variable

[GHC]

#14180: Strange/bad error message binding unboxed type variable
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        Reporter:  dfeuer            |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.2.3
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      Resolution:                    |             Keywords:  TypeInType
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 simonpj):

 > For some reason, GHC expects the type of all type variables to have kind
 Type

 It's here in `TcMType`:
 {{{
 newMetaKindVar = do { uniq <- newUnique
                     ; details <- newMetaDetails TauTv
                     ; let kv = mkTcTyVar (mkKindName uniq) liftedTypeKind
 details
                     ; traceTc "newMetaKindVar" (ppr kv)
                     ; return (mkTyVarTy kv) }
 }}}
 When we see `forall a. blah`, we give `a` the kind `\kappa : *`.   Richard
 may want to comment on why.  It'd be good to add a Note to explain.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14180#comment:9>
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