[GHC] #9858: Typeable instances should be kind-aware

[GHC]

#9858: Typeable instances should be kind-aware
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        Reporter:  dreixel           |                   Owner:
            Type:  bug               |                  Status:  merge
        Priority:  highest           |               Milestone:  7.10.2
       Component:  Compiler          |                 Version:  7.9
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |  typecheck/should_fail/T9858a,
                                     |  should_run/T9858b
                                     |                Blocking:
                                     |  Differential Revisions:  Phab:D652
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Comment (by oerjan):

 Looking at that fix, I'm not sure exactly what types trigger
 `isConstraintKind k` (does it include unapplied `Show`, say?), but
 wouldn't baking that single `Bool` test result into the `TypeRep` also fix
 things without making `Constraint`s un`Typeable`?

 Also, I am guessing you still technically have "`Typeable (=>)`" with
 identical `TypeRep` as `->`, although since they're different kinds I
 don't see how to exploit that - but that's what we thought of the `()`
 thing first. :P

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9858#comment:88>
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