As discussed between Matthias, Albrecht and Manolo, the best procedure is
- use MAC_OS_X_VERSION_MAX_ALLOWED but not __MAC_OS_X_VERSION_MAX_ALLOWED;
- compile helper file CMake /macOSMaxAllowed.c to detect whether the SDK in use
is in version above a given threshold version number;
- based upon the result of this check, decide to weakly link or not a given framework.
CMake/macOSMaxAllowed.c:
avoid C compiler warning in test code
CMake/setup.cmake, technical changes:
- optimization: test SDK 15.0.0 first to avoid unnecessary test if true
- use a function instead of a macro
- use different names for (cached) result variables
- use prefix FLTK_ for cache variables
Note: the cache variables are marked 'internal': you may need to grep
CMakeCache.txt to view them.
