[GHC] #10146: Clang CPP adds extra newline character

[GHC]

#10146: Clang CPP adds extra newline character
-------------------------------------+-------------------------------------
              Reporter:  mpickering  |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Compiler    |           Version:  7.8.4
              Keywords:  cpp         |  Operating System:  MacOS X
          Architecture:              |   Type of failure:  None/Unknown
  Unknown/Multiple                   |        Blocked By:
             Test Case:              |   Related Tickets:
              Blocking:              |
Differential Revisions:              |
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 Running the following command (taken from the settings file)

 {{{
 cat ImportsSemi.hs | gcc -E -undef -traditional -Wunicode -Wno-invalid-pp-
 token -Wno-unicode - > out.hs
 }}}

 on any file results in a file which has an extra newline character
 appended to the end. This result is different from when `gcc` is used as
 the preprocessor, in this case no extra newline is appended.

 I appreciate that this isn't important to most users but it is important
 for ghc-exactprint. With the extra newline character the EOF marker is
 moved one line further down. When we come to output the AST, we also get
 an extra newline at the bottom of the file which breaks roundtripping.

 {{{
 > gcc --version
 Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr
 --with-gxx-include-dir=/usr/include/c++/4.2.1
 Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
 Target: x86_64-apple-darwin14.0.0
 Thread model: posix
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10146>
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