[GHC] #12655: Bizarre parser problem: "Illegal bang-pattern" (something to do with CPP?)

[GHC]

#12655: Bizarre parser problem: "Illegal bang-pattern" (something to do with CPP?)
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        Reporter:  edsko             |                Owner:
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  7.4.2
      Resolution:                    |             Keywords:
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 ezyang):

 It's a bug in the lexer that was subsequently fixed. See also
 https://github.com/haskell/cabal/issues/3739#issuecomment-244950926 and
 https://github.com/ghc/ghc/commit/c250f93bd38c7d8f6453dd79dd9951f9a02bf5a7

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12655#comment:1>
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