Question

I just updated boost to version 1.48.0 on a project i am developing on OSX Lion that also includes the Cocoa headers. After doing so I got a load of errors all pointing to has_prefix_operator.hpp and has_binary_operator.hpp which all point to lines like i.e.:

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

../../boost_1_48_0/boost/type_traits/detail/has_binary_operator.hpp:157:4:
error: expected expression [1]

After trying around, since I could not really read any sense into these errors, I noticed that if I switch the inclusion order from:

#import <Cocoa/Cocoa.h>
#include <boost/type_traits.hpp>

to

#include <boost/type_traits.hpp>
#import <Cocoa/Cocoa.h>

things magically work. I am very confused about that since it worked just fine with the previous boost release and I have no clue why this is happening. Any ideas about what might be going on?

Thanks!

Answer 1

I had essentially the same problem, and with the clue from ildjam, I found the cause and a work-around.

The (terrible) macro name is check, defined in AssertMacros.h. According to the comments in that file, in the future Apple will remove the old names. For now Apple have added a work-around to suppress the old names which is to define __ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES to 0 before AssertMacros.h is processed. e.g.

#define __ASSERT_MACROS_DEFINE_VERSIONS_WITHOUT_UNDERSCORES 0
#import <Cocoa/Cocoa.h>

If you use a prefix file, then you could put the definition there. Alternatively, a direct work-around is to undef check before including type_traits.hpp.

#ifdef check
#undef check
#endif
#include "boost/type_traits.hpp"

(Details submitted to Boost Trac too: https://svn.boost.org/trac/boost/ticket/6219 )