[GHC] #9213: Maybe important CPP warnings on ghcautoconf.h from cpphs

[GHC]

#9213: Maybe important CPP warnings on ghcautoconf.h from cpphs
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        Reporter:  asr               |                   Owner:
            Type:  bug               |                  Status:  infoneeded
        Priority:  normal            |               Milestone:
       Component:  Compiler          |                 Version:  7.8.4
      Resolution:                    |                Keywords:
Operating System:  Unknown/Multiple  |            Architecture:
 Type of failure:  None/Unknown      |  Unknown/Multiple
      Blocked By:                    |               Test Case:
 Related Tickets:                    |                Blocking:
                                     |  Differential Revisions:
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Comment (by asr):

 I realised Alex is including the file {{{ghcconfig.h}}} which generates
 the warning when using cpphs.

 An example using the file
 https://github.com/simonmar/alex/blob/master/examples/Tokens.x:

 {{{
 $ ghc --version
 The Glorious Glasgow Haskell Compilation System, version 7.8.4

 $ alex --version
 Alex version 3.1.4, (c) 2003 Chris Dornan and Simon Marlow

 $ cpphs --version
 cpphs 1.18.6

 $ alex Tokens.x

 $ ghc -pgmPcpphs -optP--cpp Tokens.hs
 Warning: trailing characters after #if directive in file
 /usr/local/stow/ghc-7.8.4-bin/lib/ghc-7.8.4/include/ghcautoconf.h  at line
 383 col 1:  AC_APPLE_UNIVERSAL_BUILD
 [1 of 1] Compiling Main             ( Tokens.hs, Tokens.o )
 Linking Tokens ...

 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9213#comment:7>
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