[GHC] #8528: Preprocessor issues building GHC HEAD on Mavericks

[GHC]

#8528: Preprocessor issues building GHC HEAD on Mavericks
----------------------------------------+----------------------------------
        Reporter:  guest                |            Owner:
            Type:  bug                  |           Status:  new
        Priority:  high                 |        Milestone:
       Component:  Compiler             |          Version:  7.7
      Resolution:                       |         Keywords:  clang
Operating System:  MacOS X              |     Architecture:  x86_64 (amd64)
 Type of failure:  Building GHC failed  |       Difficulty:  Unknown
       Test Case:                       |       Blocked By:
        Blocking:                       |  Related Tickets:  #8480
----------------------------------------+----------------------------------

Comment (by hvr):

 Btw, deciding whether Alex is to blame or rather GHC, and how to actually
 *fix* the situation really depends on what the
 formal specification for `{-# LANGUAGE CPP #-}` actually is... but I
 couldn't find any :-/

 The way I understand it, Haskell code on Hackage using CPP seems to have
 implicitly assumed for several years that

  http://gcc.gnu.org/onlinedocs/cpp/Traditional-Mode.html

 is the underlying CPP model.  However, Clang's cpp obviously implements
 different semantics and/or doesn't implement traditional mode at all.  So
 this actually a much larger issue, and it isn't enough to just patch code
 to compile with both Clang's cpp and GCC's cpp (and hope it doesn't break
 again, as developers generally don't have both cpp implementation
 available for testing)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8528#comment:6>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler