[Boost-bugs] [Boost C++ Libraries] #6219: Apple macros break compile of has_binary_operator

Subject: [Boost-bugs] [Boost C++ Libraries] #6219: Apple macros break compile of has_binary_operator
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2011-12-05 21:41:42

#6219: Apple macros break compile of has_binary_operator
------------------------------------------------+---------------------------
 Reporter:  John Gee <j.gee@…>                  |       Owner:         
     Type:  Bugs                                |      Status:  new    
Milestone:  To Be Determined                    |   Component:  None   
  Version:  Boost 1.48.0                        |    Severity:  Problem
 Keywords:                                      |  
------------------------------------------------+---------------------------
 Short version: the Apple defined macro for check() breaks the compile of
 some files in Boost 1.48.


 Long version

 I upgraded from Boost 1.44 to 1.48 and my compile broke. A little digging
 determined it is a conflict with the check() macro defined in
 AssertMacros.h which currently makes its way into many compiles. This
 problem has come up before, see
 [https://svn.boost.org/trac/boost/ticket/2115].

 I am compiling on Mac OS X Lion v10.7.2 with Apple LLVM compiler 3.0. This
 code is enough to show the problem:

 #include <Carbon/Carbon.h>
 #include "boost/type_traits.hpp"

 or more directly
 #include <AssertMacros.h>
 #include "boost/type_traits.hpp"

 The first errors happen in this code in has_binary_operator.hpp where
 check is used.

 {{{
 template < typename Lhs, typename Rhs >
 struct operator_exists {
    static ::boost::type_traits::yes_type check(has_operator); // this
 version is preferred when operator exists
    static ::boost::type_traits::no_type check(no_operator); // this
 version is used otherwise

    BOOST_STATIC_CONSTANT(bool, value = (sizeof(check(((make<Lhs>()
 BOOST_TT_TRAIT_OP
 make<Rhs>()),make<has_operator>())))==sizeof(::boost::type_traits::yes_type)));
 };
 }}}

 Of some interest, Apple is aware of the problems being caused by the too-
 ordinary macro names and this text appears in the AssertMacros.h header:

 {{{
 *      Prior to Mac OS X 10.6 the macro names used in this file conflicted
 with some
  *      user code, including libraries in boost and the proposed C++
 standards efforts,
  *      and there was no way for a client of this header to resolve this
 conflict. Because
  *      of this, most of the macros have been changed so that they are
 prefixed with
  *      __ and contain at least one capital letter, which should alleviate
 the current
  *      and future conflicts.  However, to allow current sources to
 continue to compile,
  *      compatibility macros are defined at the end with the old names.  A
 tops script
  *      at the end of this file will convert all of the old macro names
 used in a directory
  *      to the new names.  Clients are recommended to migrate over to
 these new macros as
  *      they update their sources because a future release of Mac OS X
 will remove the
  *      old macro definitions ( without the double-underscore prefix ).
 Clients who
  *      want to compile without the old macro definitions can define the
 macro
  *      __ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES to 0 before
 this file is
  *      included.
 }}}

 (So there is a work-around in client code.)

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6219>
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