[GHC] #7070: "the 'impossible' happened"

[GHC]

#7070: "the 'impossible' happened"
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 Reporter:  aristidb            |          Owner:                
     Type:  bug                 |         Status:  new           
 Priority:  normal              |      Component:  Compiler      
  Version:  7.4.2               |       Keywords:                
       Os:  Linux               |   Architecture:  x86_64 (amd64)
  Failure:  Compile-time crash  |       Testcase:                
Blockedby:                      |       Blocking:                
  Related:                      |  
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Comment(by aristidb):

 So I succeeded at creating a minimal test example. It _is_ related to
 DataKinds, and it's remarkable how little code is needed to trigger it.
 I'm going to attach it as a tarfile, and as a small Github repository for
 easier browsing: https://github.com/aristidb/data-kinds-haskell-bug

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Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7070#comment:3>
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