[GHC] #8412: TH allows negative type-level integers

[GHC]

#8412: TH allows negative type-level integers
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       Reporter:  monoidal           |             Owner:
           Type:  bug                |            Status:  new
       Priority:  normal             |         Milestone:
      Component:  Compiler           |           Version:  7.6.3
       Keywords:                     |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple   |   Type of failure:  GHC accepts
     Difficulty:  Easy (less than 1  |  invalid program
  hour)                              |         Test Case:
     Blocked By:                     |          Blocking:
Related Tickets:                     |
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 Similar to #8306, it is possible to create type-level -1 via

 {{{
 type T = $(return $ LitT $ NumTyLit (-1))
 }}}

 Easy to fix with new TH by moving the check from parser to renamer. I'm
 preparing a patch.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8412>
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