 ifdef HAVE_WEAK_IMPORT
#	if !defined(HAVE_AVAILABILITYMACROS_H) || !defined(MAC_OS_X_VERSION_MIN_REQUIRED)
#	    undef HAVE_WEAK_IMPORT
#	else
#	    ifndef WEAK_IMPORT_ATTRIBUTE
#		define WEAK_IMPORT_ATTRIBUTE	__attribute__((weak_import))
#	    endif
#	endif
#   endif /* HAVE_WEAK_IMPORT */

/*
 *---------------------------------------------------------------------------
 * Support for MAC_OS_X_VERSION_MAX_ALLOWED define from AvailabilityMacros.h:
 * only use API available in the indicated OS version or earlier.
 *---------------------------------------------------------------------------
 */

#   ifdef MAC_OS_X_VERSION_MAX_ALLOWED
#	if MAC_OS_X_VERSION_MAX_ALLOWED < 1050 && defined(__LP64__)
#	    undef HAVE_COREFOUNDATION
#	endif
#	if MAC_OS_X_VERSION_MAX_ALLOWED < 1040
#	    undef HAVE_OSSPINLOCKLOCK
#	    undef HAVE_PTHREAD_ATFORK
#	    undef HAVE_COPYFILE
#	endif
#	if MAC_OS_X_VERSION_MAX_ALLOWED < 1030
#	    ifdef TCL_THREADS
		/* prior to 10.3, realpath is not threadsafe, c.f. bug 711232 */
#		define NO_REALPATH 1
#	    endif
#	    undef HAVE_LANGINFO
#	endif
#   endif /* MAC_OS_X_VERSION_MAX_ALLOWED */
#   if defined(HAVE_COREFOUNDATION) && defined(__LP64__) && \
	    defined(HAVE_WEAK_IMPORT) && MAC_OS_X_VERSION_MIN_REQUIRED < 1050
#	warning "Weak import of 64-bit CoreFoundation is not supported, will not run on Mac OS X < 10.5."
#   endif

/*
 *---------------------------------------------------------------------------
 * At present, using vfork() instead of fork() causes execve() to fail
 * intermittently on Darwin x86_64. rdar://4685553
 *---------------------------------------------------------------------------
 */

#   if defined(__x86_64__) && !defined(FIXED_RDAR_4685553)
#	undef USE_VFORK
#   endif /* __x86_64__ */
/* Workaround problems with vfork() when building with llvm-gcc-4.2 */
#   if defined (__llvm__) && \
	    (__GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ > 2 || \
	    (__GNUC_MINOR__ == 2 && __GNUC_PATCHLEVEL__ > 0))))
#	undef USE_VFORK
#   endif /* __llvm__ */
#endif /* __APPLE__ */
