[GHC] #12456: Panics when making a quotation as pattern synonym

[GHC]

#12456: Panics when making a quotation as pattern synonym
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           Reporter:  Iceland_jack   |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.0.1
           Keywords:                 |  Operating System:  Unknown/Multiple
  PatternSynonyms                    |
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 {{{
 $ ghci -XPatternSynonyms -XViewPatterns -ignore-dot-ghci
 GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
 Prelude> :m + Language.Haskell.TH
 Prelude Language.Haskell.TH> pattern A :: ExpQ; pattern A <- (undefined ->
 ()) where A = undefined
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.0.1 for x86_64-unknown-linux):
         nameModule system $dIP_a4HS

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 Prelude Language.Haskell.TH>
 }}}

 should we be able to use quotations that are pattern synonyms? I have no
 use for this.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12456>
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