[GHC] #13844: Surprising behavior with CPP extension

[GHC]

#13844: Surprising behavior with CPP extension
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        Reporter:  deech             |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.0.2
      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 bgamari):

 Mmm, this is unfortunate. Eliding comments prior to pre-processing is not
 trivial but could be done. We would need a simple parser which would also
 produce `#line` pragmas to ensure that line information is correct in the
 post-CPP parse.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13844#comment:1>
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